This publication is Open Access under the license indicated. Learn More
Article
Shaking-Induced Aggregation and Flotation in Immunoglobulin Dispersions: Differences between Water and Water–Ethanol MixturesClick to copy article linkArticle link copied!
- Nikolai F. Bunkin*Nikolai F. Bunkin*Email: [email protected]Bauman Moscow State Technical University, 2-nd Baumanskaya str. 5, Moscow 105005, RussiaProkhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, RussiaMore by Nikolai F. Bunkin
- Alexey V. ShkirinAlexey V. ShkirinProkhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, RussiaNational Research Nuclear University MEPhI, Kashirskoe sh. 31, Moscow 115409, RussiaMore by Alexey V. Shkirin
- Barry W. NinhamBarry W. NinhamThe Australian National University, Acton, Canberra ACT 2600, AustraliaMore by Barry W. Ninham
- Sergey N. ChirikovSergey N. ChirikovNational Research Nuclear University MEPhI, Kashirskoe sh. 31, Moscow 115409, RussiaMore by Sergey N. Chirikov
- Leonid L. ChaikovLeonid L. ChaikovLebedev Physics Institute of the Russian Academy of Sciences, Leninskiy pr. 53, Moscow 119991, RussiaMore by Leonid L. Chaikov
- Nikita V. PenkovNikita V. PenkovFederal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, Institutskaya str. 3, Pushchino 142290, Moscow region, RussiaMore by Nikita V. Penkov
- Valeriy A. KozlovValeriy A. KozlovBauman Moscow State Technical University, 2-nd Baumanskaya str. 5, Moscow 105005, RussiaProkhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, RussiaMore by Valeriy A. Kozlov
- Sergey V. GudkovSergey V. GudkovProkhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, RussiaMore by Sergey V. Gudkov
Abstract
Click to copy section linkSection link copied!
Structural characterization by three complementary methods of laser diagnostics (dynamic light scattering, laser phase microscopy, and laser polarimetric scatterometry) has established that shaking of immunoglobulin G (IgG) dispersions in water and ethanol–water mixtures (36.7 vol %) results in two effects. First, it intensifies the aggregation of IgG macromolecules. Second, it generates bubbles with a size range that is different in each solvent. The aggregation is enhanced in ethanol–water mixtures because of IgG denaturation. IgG aggregates have a size of ∼300 nm in water and ∼900 nm in ethanol–water mixtures. The flotation of IgG is much more efficient in water. This can be explained by a better adsorption of IgG particles (molecules and aggregates) on bubbles in water as compared to ethanol–water mixtures. Bulk nanobubbles and their association with IgG aggregates were visualized by laser phase microscopy in water but were not detected in ethanol–water mixtures. Therefore, the nanobubble flotation mechanism for IgG aggregates acting in water is not feasible for ethanol–water mixtures.
Copyright © 2020 American Chemical Society
1. Introduction
Click to copy section linkSection link copied!
A number of technologies involve the effects of mechanical impacts on water and aqueous solutions. In some cases, mechanical impacts can lead to a significant acceleration of various chemical and physical processes. (1−5) Vibration treatment, in particular, shaking, is widely used in technological procedures, typically those that require fluid mixing to enhance dissolution of chemical compounds. Another example is reaching ultralow concentrations with the use of sequential dilutions.
In this study, the effects of shaking are explored for dispersions of large protein macromolecules, immunoglobulin G (IgG), in two different media: water and an ethanol–water mixture (EWM). It is worth noting that ethanol (36.7 vol %) is one of the pharmacopoeial alcohols used in pharmaceutics. (6) It is known that shaking IgG solutions enhances the natural aggregation of IgG molecules (7,8) and can change the morphology of protein aggregates, used for therapeutic purposes. (9) In addition to aggregation, shaking has another effect: the flotation of IgG molecules and aggregates due to their attachment to bubbles and stabilization of bubbles. Shaking-induced flotation gives results similar to electroflotation, where bubbles are also formed during electrolysis. Electroflotation is used in food technology to extract proteins from multicomponent aqueous mixtures. (10)
Flotation is efficient provided that the floating bubbles have a sufficient lifetime for particle-bubble adhesion to occur. (11−15) Here, the size of bubbles plays a key role because even micron-sized bubbles have insufficient lifting power and the same being true a fortiori for nanobubbles. Nanobubbles are incapable of rising in water because of their almost neutral buoyancy. (16,17) This is because they are metastable, “dressed” with impurities, or with surfactants or adsorbed salt. However, they can aggregate with suspended colloidal particles and thereby act as “secondary collectors”, thereby, improving particle flotation. (18,19) In addition, nanobubbles can serve as nuclei (“seeds”) for the adhesion of particles on coarser bubbles, including macrobubbles (>100 μm in diameter), see ref (20). In the same way, we can expect equally that sufficiently stable nanobubbles can be the source of depletion forces to inhibit bubble–bubble fusion. (21−23) Furthermore, it can be shown that charged nanobubbles with adsorbed proteins provide a stabilizing double layer force between the macrobubbles, just as micelles stabilize microemulsion or emulsion drops. This is, of course, counterintuitive, but the situation with bubbles is quite analogous to charged micelles. (24,25)
To summarize, the combination of nanobubbles, microbubbles, and macrobubbles provides a bewildering complex and highly organized “soup”. It can lead to capture of colloidal particles, that is, nanobubbles enhance the attachment of these particles to larger bubbles and thus increase the flotation efficiency, or vice versa, depending on protein surface hydrophobicity and charge. Control of these processes is the main game.
Nanobubbles, being stable or not, are effectively nucleated by stirring. (26,27) One consequence of shaking is that the layers of liquid adjacent to the vial surfaces have a lower speed relative to more distant layers. Close to the vial side, the liquid is completely immobile. Because of this inequality of the velocities of neighboring layers, discontinuities in the liquid inevitably arise. These discontinuities are filled with gas molecules and the process opposes the instantaneous collapse of the cavities formed. Chaotropic (structure-breaking) ions are capable of adsorbing on the internal surface of the cavity. (28) This could lead to the appearance of electrical charge on the surface (note that some amount of external ionic impurity is always present in purified water anyway). Furthermore, the process of adsorption and desorption of these ions on the charged surface eventually results in the formation of a stable gas bubble with diameters ∼300 nm. We have termed such structures “bubstons”, that is, bubbles stabilized by ions. (27−29)
The IgG dispersions were analyzed by laser methods: dynamic light scattering (DLS), laser phase microscopy (LPM), and laser polarimetric scatterometry (LPS). The techniques are described in detail, for example, in refs. (27,30) The joint use of these methods enabled us to detect and characterize particles with greater or less information and accuracy at very wide scales ranging from ∼1 to 104 nm.
2. Results and Discussion
Click to copy section linkSection link copied!
2.1. Nanobubble Generation by Shaking: Comparison of Pure Water and an EWM
From the Introduction, it can be concluded that vigorous shaking should produce gas nanobubbles in aqueous media. In the literature, nanobubbles are understood to mean long-lived gas-filled cavities with a diameter of less than a micron. As was recently shown, (26) nanometer-sized oxygen bubbles could be produced by vibration, and their concentration and size distribution were measured by nanoparticle tracking analysis. It turned out that the concentration of bulk nanobubbles largely increases after vibration treatment and is determined by the vibration frequency and time. Here, we also studied the influence of shaking on the volume number density of gas nanobubbles in water and a water–ethanol mixture.
We performed DLS measurements in water before and immediately after shaking (see Figure 1). The component at 0.5 nm can be associated with short-lived ice-like clusters consisting of ∼4–5 water molecules that are included in the first coordination sphere (hydration shell, see, e.g., ref (31)). The component at 250 nm is related to the bubston phase. This is also supported by LPM data (see Figure 2).
Figure 1
Figure 1. DLS intensity distribution over the particle sizes in water: before shaking (blue solid curve) and immediately after shaking (red dashed curve). Total scattering intensities are Itot(173°) = 12 kcps (0.5 nm—62.2%, 250 nm—37.8%) and Itot(173°) = 40 kcps, correspondingly.
Figure 2
Figure 2. LPM images of a bubston with d ≈ 250 nm in water after shaking: (a) 2D distribution of the optical path difference (OPD) and (b) 1D profile, Δh = −20 nm.
Figure 2a shows two-dimensional (2D) distribution of the optical phase shift across a separate bubston with a size of ≈250 nm (the half-height estimate). Exactly the same size was measured by DLS both before and after shaking. Figure 5b shows a one-dimensional (1D) profile drawn through the center of the bubston.
From the distribution shown in Figure 1, it is possible to evaluate the change in the volume number density of the bubstons immediately after shaking. The percentage ratio of the peak intensities at 250 nm before and after shaking gives the value 
, which is equal to the ratio of the nanobubble number density after/before shaking. A similar increase in the volume number density of nanobubbles after shaking is observed in ref (26).
, which is equal to the ratio of the nanobubble number density after/before shaking. A similar increase in the volume number density of nanobubbles after shaking is observed in ref (26).In Figure 3, we exhibit the results of DLS measurements in an EWM before and immediately after shaking. In this case, the ratio of the scatterer number density is 
, that is, the number of scatterers per volume remains the same.
, that is, the number of scatterers per volume remains the same.Figure 3
Figure 3. DLS intensity distribution over the particle sizes in an EWM: before shaking (blue solid curve) and immediately after shaking (red dashed curve). Total scattering intensities are Itot(173°) = 80 kcps and Itot(173°) = 85 kcps, correspondingly.
Figure 4 shows a characteristic 2D distribution and the corresponding 1D profile for 150 nm inhomogeneities observed in the initial water–ethanol solution. The height of the profile Δh makes it possible to assign the observed inhomogeneities to mesodroplets enriched with ethanol, see our recent studies. (32,33) However, we cannot exclude that in that case, we deal with artifacts associated with interference noise. (34) Thus, we conclude that in this case, the scatterers are liquid mesodroplets, whose volume number density is not changed in the process of shaking.
Figure 4
Figure 4. LPM images of a mesoscale particle with a size of d ≈ 150 nm, presumably, an ethanol-enriched mesodroplet in an unshaken EWM: (a) 2D distribution of the OPD and (b) 1D profile of this particle, Δh ≈ 7 nm.
In this regard, it is worth mentioning the study, (35) where it is claimed that when ethanol is added to water, the volume number density of gas nanobubbles increases compared to aqueous samples treated with a continuous high-shear rotor-stator device, that is, actually after vigorous vibrations. The authors (35) conclude that there are no nanodroplets of alcohol in the water–alcohol mixture and they observed gas nanobubbles, but this conclusion is based on indirect data because the nanoparticle tracking analysis method used in ref (35) is unable to distinguish between a nanodroplet and a nanobubble. At the same time, using the phase microscopy technique, which allows us to directly distinguish gas nanobubbles from nanodroplets, we did not find gas nanobubbles in water-alcohol mixtures.
2.2. Solution of IgG in Water: Characterization of IgG Aggregates
Figure 5 depicts the results of DLS experiments in aqueous IgG solution, with the volume number density of IgG macromolecules being 3 × 1014 cm–3. The size distribution consists of two peaks: a peak at 12 nm can be associated with monomeric IgG molecules. (36) We believe that the 300 nm peak is related chiefly to IgG aggregates. In this figure, we exhibit the average total intensity, from which the Rayleigh scattering (IR(173°) ≈ 10 kcps) is subtracted, Itot(173°) = 255 kcps. The peak at 300 nm amounts to 81.8% of the total intensity, while the 12 nm peak is related to 18.2% of the total intensity. We also measured the average intensity of the scattered light I(θ) at a scattering angle of θ = 173°, which allows us to estimate the volume number density of scatterers α in accordance with eq 7 (see Section 6.1) provided that the scattering cross section Csca and scattering indicatrix F(θ) of single scatterer are known. Representation of monomeric IgG molecules as spheres with a size of 12 nm allows us to calculate Csca = 0.27 × 10–10 μm2 and F(173°) = 1.49; thus, for the monomers, we have α = 2.4 × 1014 cm–3. This is in good agreement with the nominal concentration of the solution, see Section 4. By calculation for the particles with a size of 300 nm (assuming their sphericity) Csca = 0.2193 × 10–2 μm2 and F(173°) = 0.37, we obtain α = 5.4 × 107 cm–3.
Figure 5
Figure 5. DLS intensity distribution over the particle sizes in aqueous IgG solution with volume number density 3 × 1014 cm–3 before shaking. Average total intensity (minus background scattering) Itot(173°) = 255 kcps (12 nm peak is 18.2% and 300 nm peak is 81.8%).
For the volume number density of such mesodroplets shown in Figures 3 and 4, in accordance with eq 7, we obtain α ≈ 109 cm–3. It is important that small hydrophobic particles can play the role of nucleation centers for self-assembly of organic liquid molecules, which gives rise to the mesodroplet generation, (37) that is, some IgG molecules can be encapsulated into ethanol mesodroplets.
In Figure 6, the results obtained by LPM are presented. Panel (a) shows the 2D distribution of the optical phase shift across two closely located particles with a size of 300 nm; particles of this size were also detected in the DLS experiment. Panel (b) shows the 1D profile of these particles, which was drawn through their centers. The phase profile of 300 nm solid particles (Figure 6b) allows us to estimate its refractive index as n = 1.5 ± 0.02 according to the calibration curve (see Section 5.3). Refractive index measurements for various proteins (38) show that they typically have n ≥ 1.53 (being proteins, IgGs are assumed to obey this inequality). Therefore, a rather low value of n measured by LPM indicates that we most likely deal with 300 nm aggregates of individual IgG molecules with a size of ∼12 nm, separated by water monolayers. The fractal properties of these aggregates were investigated with the help of the scattering matrix technique (see below). Note that the observed convergence of submicron IgG aggregates can be the initial stage of the macroaggregate formation, which is typical for proteins.
Figure 6
Figure 6. LPM images of inhomogeneities in aqueous IgG solution before shaking: (a) 2D distribution of the OPD for particles with a size of about 300 nm and (b) 1D profile of this distribution, Δh ≈ 25 nm.
To make sure that IgG aggregation indeed takes place and to determine the fractal dimensions of the aggregates, the angular dependences of the scattering matrix elements for the IgG solution were measured. The knowledge of the fractal dimension allows one to determine the type of monomer aggregation. (39) The experimental data were compared with theoretical dependences calculated using the T-matrix method. (40) As was shown in that work, the analysis of the angular dependences of the scattering matrix elements allows us to find the size distribution of particles, provided that the size does not exceed the radiation wavelength.
In the case where the size of particles exceeds the wavelength, we can find out whether these particles are “monolithic” or clustered particles having a fractal inner structure. (39) For an isotropic medium with randomly oriented scatterers, the 4 × 4 scattering matrix F(θ) has a block-diagonal form: (41) the elements F14, F41, F24, F42, F31, F32, F13, and F23 are zero, F12 = F21, and F34 = −F43. In addition, for spherical particles, we have F33 = F44 and F22 = 1. Summarizing, the scattering matrices of media with spherical particles are completely described by the angular dependences F11(θ), F12(θ), F34(θ), and F44(θ).
In Figure 7, we show the experimental and theoretical angular dependences of the scattering matrix elements for the initial aqueous IgG solution with volume number density 3 × 1014 cm–3. The matrix element values, measured at θ < 10° and θ > 90°, are not given because of the contribution of distorting factors, for example, reflection from the vial sides. Here, fij(θ) = Fij(θ)/F11(θ) are the normalized elements; F11(θ) describes the scattering indicatrix. The dependencies f12(exp) (θ), f34(exp) (θ), and f44(exp) (θ) are similar to those for Rayleigh scattering (dashed lines), while the dependence F11(exp) (θ) for the IgG solution at large angles is well-described by the expression A0(sin(θ/2))−Df (dashed line), where A0 is a constant. A scattering matrix of this type is characteristic for the media containing clusters, whose monomers (IgG macromolecules, in our case) have a size much smaller than the radiation wavelength. Df means the fractal dimension of the cluster (41) (see Section 6.2). Slight deviations of f12(exp) (θ), f34(exp) (θ), and f44(exp) (θ) from the elements of the Rayleigh scattering matrix at large angles are apparently because of multiple scattering.
Figure 7
Figure 7. Dependences of the scattering matrix elements F11(θ), f12(θ), f34(θ), and f44(θ) measured via LPS in aqueous IgG solution before shaking. The circles are experimental points, the solid line is the theoretical approximation by multitype spherical particles, and the dashed line is the Rayleigh–Gans–Debye approximation for the IgG aggregates. F11(exp) (θ) is plotted so that F11(exp) (30°) = F11(theor) (30°); for more detail, see ref (40).
The element F11theor(θ) calculated in accordance with eq 8 (Section 6.2) is shown in Figure 7 (solid black curves). The fractal dimension estimated using eq 9 for the IgG aggregates in aqueous solution is Df = 2.7. Such values are typical for the aggregation mechanism according to the “monomer–cluster” scenario. (42) As follows from these diagrams, noticeable discrepancies between the theoretical approximation and the experimental results are observed at θ < 20°, where the condition qRg > 1 does not hold.
2.3. IgG Flotation Efficiency with Shaking Aqueous Solutions
Figure 8 shows the scatterer size distribution of DLS intensity in the initial aqueous IgG solution immediately after shaking. Because in this experiment, the scattering volume was fixed at a level of half-height of the cell with liquid, the results are related to the bulk of the liquid sample.
Figure 8
Figure 8. DLS intensity distribution over the particle sizes in aqueous IgG solution with volume number density 3 × 1014 cm–3 immediately after shaking. Average total intensity (background scattering is subtracted) Itot(173°) = 844 kcps (12 nm peak is 4.8%, 250 nm peak is 45.1%, 600 nm peak is 30.5%, and 3000 nm peak is 19.6%).
As seen in Figure 8, immediately after shaking, particles with a mean size d ≈ 200, 600, and 3000 nm are formed. In accordance with our previous results, (27,28) scatterers with diameters of 200–300 nm correspond to bubstons; the same size can relate to IgG aggregates (see Figures 6 and 8). Because bubstons are effectively negatively charged, (27,28) they can form complexes with IgG aggregates. The peak centered at 600 nm apparently corresponds to small clusters consisting of IgG aggregates and bubstons (in particular, dimers), while the peak at 3000 nm is associated with larger “bubston–IgG aggregate” complexes and/or micron-sized bubbles stabilized by IgG absorbed on its surface. (43,44) All these types of particles can adhere to larger micro- and macrobubbles and, thereby, float to the liquid surface.
As follows from the comparison of the diagrams in Figures 5 and 8, the area of the peak corresponding to the IgG molecules of 12 nm in size decreased. During the experiment, the cell was sealed, that is, the total amount of IgG in the liquid could not decrease. Thus, the only mechanism leading to the redistribution of IgG molecules between the bulk liquid and free surface is flotation: IgG molecules together with IgG aggregates are transferred by floating bubbles from the bulk to the surface of the liquid.
We define the flotation coefficient for IgG molecules as Km = (I0(m) – I(m))/I0(m) = 1 – I(m)/I0(m) = 1 – 40.5/46.4, where I0(m) and I(m) are the peak intensities (measured in count rate units) at ∼10 nm in the distributions, as shown in Figures 5 and 8, that is, before and after shaking, respectively. The change in IgG amount due to flotation is given by the formula ΔN = N0 – N = Km·N0. On the basis of the diagrams shown in Figures 5 and 8, we arrive at Km ≈ 0.13. This is an upper estimate because some of the individual IgG molecules were aggregated by shaking, and, most likely, not all newly formed IgG aggregates were captured by flotation.
The fact that the agglomerates of IgG aggregates and bubbles do exist was confirmed by the LPM study of a foam sample, taken via a pipette from the surface of the initial IgG solution immediately after shaking. In Figure 9, we give typical patterns of the 2D distribution of OPDs (and the corresponding 1D profiles) for particles inside the foam. As follows from the diagrams, we are dealing with composite particles having simultaneously a concave profile (in accordance with eq 1, such particles are gas bubbles) and a convex profile (particles, whose refractive index exceeds that of water). Figure 9a,b shows a bubble with a size of 400 nm (estimated at the level of half-height of a concave part of the profile), which forms a dimer with a solid particle (most likely, IgG aggregates). The profile is somewhat broadened because of Brownian motion, that is, the real particle size of the dimer is smaller. Figure 9c,d shows an agglomerate of nanobubbles and IgG aggregates. The structures imaged at Figure 9 sustain the model, (43) considering the adsorption of protein molecules at the bubble interface to be followed by surface denaturation of these macromolecules and their subsequent aggregation. This means that the bubble surface is covered by IgG aggregates rather than single protein macromolecules. (44)
Figure 9
Figure 9. Characteristic LPM images (2D distributions of the OPD and the corresponding 1D profiles) of particles in a sample taken from the surface of the initial aqueous IgG solution (volume number density 3 × 1014 cm–3) immediately after shaking: (a,b) nanobubble–IgG aggregate dimer and (c,d) agglomerate of nanobubbles and IgG aggregates.
As far as we cannot estimate correctly the volume number density of IgG aggregates in the bulk immediately after shaking, we should employ a protocol, different from that of IgG monomers, in determining the flotation coefficient Ka for these aggregates. Specifically, to estimate Ka, we have determined the amount of IgG aggregates that appeared on the surface of IgG solution as a result of shaking by measuring the volume concentration of IgG aggregates in 100-fold dilution of an aliquot taken from the surface of the shaken solution. The scattering intensity distribution measured by DLS in the diluted shaken solution is shown in Figure 10. In this diagram, we do not see the peak corresponding to monomeric IgG molecules with a size of 12 nm. Indeed, we can express the volume number density of IgG molecules in the diluted shaken solution in the number of photocounts per time units. Bearing in mind that in the initial solution, N0 = 46.4 kcps (see the comments to Figure 5) and Km ≈ 0.13, we have the estimate N1 = 46.4·Km ≈ 6 kcps, which is lower than the Rayleigh baseline (10 kcps), and therefore, the corresponding peak is hard to resolve. Another possible reason for the invisibility of the peak of monomers is their aggregation/adhesion on the surface of micron-sized bubbles. At the same time, a peak at 300 nm, which is evidently related to IgG aggregates, is clearly visible. In addition, one can see a peak in the region of several microns, which is most likely associated with micron-sized bubbles.
Figure 10
Figure 10. DLS intensity distribution over the particle sizes in 100-fold dilution of shaken aqueous IgG solution (the initial concentration 3 × 1014 cm–3). Average total intensity (minus background scattering) Itot(173°) = 21 kcps (250 nm peak is 62% and 3000 nm peak is 38%).
Bearing in mind the dilution ratio (0.01, in our case), we obtain that the flotation coefficient for IgG aggregates in water Ka = I1(a)/I0(a) – 0.01 = 5%, where I0(a) and I1(a) are peak intensities at ∼ 300 nm in the distributions, as shown in Figure 8 (initial solution after shaking) and Figure 10 (100-fold diluted shaken solution). We can see that the flotation of monomeric IgGs is more efficient than that of their aggregates, which is obviously due to the lower volume number density of the aggregates.
2.4. Solution of IgG in an EWM: Characterization of IgG Aggregates
Figure 11 shows the results of DLS experiments with a solution of IgG in an EWM (the number of IgG molecules per unit volume is 3 × 1014 cm–3). As follows from Figure 11a, the aggregation of IgG monomers develops more intensively in an EWM than in water: in the scattered intensity distribution, we cannot see particles with a size of 12 nm, and the resultant aggregates are significantly larger than in those aqueous solutions; their size was about 900 nm (Figure 11a). To study smaller-sized fractions (of about 450 nm or less), the initial IgG solution was filtered through a membrane with a pore diameter of 450 nm (Figure 11b). As follows from the graph, a peak, centered at 900 nm, has the same physical nature as the corresponding peak in panel (a), but its intensity is significantly lower than that in the unfiltered sample. Apparently, this is due to the fast emergence of new aggregates after filtration. Because of the elimination of large particles and a decrease in the total scattering intensity by 116 times, individual molecules (12 nm) become visible. Furthermore, there can be seen a peak at ∼150 nm, which is characteristic for pure ethanol mesodroplets in an EWM, (32,33) and a peak at d = 12 nm, corresponding to monomeric IgG molecules. To trace the behavior of monomer and aggregate peaks, we applied the shaking procedure (described in Section 5.1) to the filtered IgG solution (Figure 11b); the resulting distribution is shown in Figure 11c. At the first glance, it may seem strange that in an EWM, we see the same size of IgG molecules as in water, that is, the peak corresponding to IgG molecules in the native form (12 nm). Seemingly, the denatured protein molecules have enough time to assemble into aggregates; therefore, native IgG predominates in the peak of individual molecules.
Figure 11
Figure 11. DLS intensity distribution over the particle sizes: (a) initial IgG solution in an EWM (36.7 vol %) with a volume number density of IgG molecules being 3 × 1014 cm–3, Itot(173°) = 5820 kcps before shaking; (b) same solution after filtration through a membrane with a pore size of 450 nm, Itot(173°) = 50 kcps (12 nm peak is 40%, 150 nm peak is 50%, and 900 nm peak is 10%); and (c) filtered solution immediately after shaking Itot = 389 kcps, 12 nm peak is 5%, 120 nm peak is 5.7%, and 400 nm peak is 89.3%). Here, Itot is the average total intensity (background scattering was subtracted).
The shaking process initiates the aggregation of IgG molecules so that the new aggregates about 400 nm in size appear and the total scattering intensity increases greatly (Figure 11c). As a result, larger aggregates ∼900 nm that existed in the solution before shaking in small quantities become invisible possibly because of their fragmentation. The aggregative nature of the 400 nm peak is confirmed by the fact that shaking of the pure (IgG-free) EWM (36.7 vol %) does not lead to any changes in the total scattering intensity and its scatterer size distribution (a peak corresponding to nanobubbles does not appear); the distribution in the EWM has only one peak in the 100 nm range related to ethanol mesodroplets.
Figure 12 shows the distribution corresponding to the solution in the EWM filtered through a porous membrane (pore diameter 0.45 μm), which was further filtered using a membrane with a pore size of 220 nm; the distribution peak corresponding to IgG aggregates completely disappeared. In this case, the peak corresponding to individual molecules is shifted to the right compared to Figure 11b in the position of 18 nm, which indicates an increase in the effective size of IgG molecules because of denaturation. An additional peak at a 4 Å scale (the characteristic size of an ethanol molecule) associated with molecular scattering is clearly observed. The effect of the IgG peak shift can be associated with a strong decrease in the concentration of IgG molecules, and because it is known that denatured protein molecules aggregate more efficiently than the native ones, at a lower concentration of IgG molecules, the IgG molecules in the denatured form do not have enough time to aggregate and we see an increase in the contribution of the denatured IgG molecules to the peak of the individual molecules, which causes the shift of this peak toward large sizes.
Figure 12
Figure 12. DLS intensity distribution over the particle sizes in the initial IgG solution (3 × 1014 cm–3) after filtration through a membrane with a pore size of 220 nm, Itot(173°) = 27 kcps (4.5 nm peak is 22.8%, 18 nm peak is 31.4%, and 170 nm peak is 45.8%).
Figure 13 shows the LPM image of a particle, related to the 900 nm peak observed by DLS in EWM solution of IgG with volume number density α1 = 3 × 1014 cm–3 (see Figure 11a). The phase profile (Figure 13b) allows us to estimate the refractive index of such particles; we obtain n = 1.51 ± 0.02, which can be related to IgG aggregates, see the comments to Figure 5. Taking into account the measured average intensity I(173°) = 5400 kcps, we can estimate the volume number density α2 of 900 nm IgG aggregates through their scattering cross section Csca = 0.2943 μm2; F(173°) = 0.026, see the comments to eqs 4 and 5. Thus, we obtain α2 ≈ 1.7 × 108 cm–3.
Figure 13
Figure 13. LPM images of a particle with a size of ≈900 nm in EWM solution of IgG before shaking: (a) 2D distribution of the OPD and (b) 1D profile of the distribution.
In Figure 14, we exhibit the experimental and theoretical angular dependences of the scattering matrix elements for the initial solutions of IgG in an EWM (3 × 1014 cm–3). Using the same algorithm for the analysis of matrix elements as for the aqueous IgG solution (Section 2.1), we estimated the fractal dimension of IgG aggregates in the EWM Df = 2.8.
Figure 14
Figure 14. Dependences of the scattering matrix elements F11(θ), f12(θ), f34(θ), and f44(θ) measured via LPS in EWM solution of IgG before shaking. The circles are experimental points, the solid line is the theoretical approximation by multitype spherical particles, and the dotted line is the Rayleigh–Gans–Debye approximation for IgG aggregates. As in Figure 7, F11(exp) (θ) is plotted so that F11(exp) (30°) = F11(theor) (30°).
2.5. IgG Flotation Efficiency with a Shaken EWM
To determine the flotation coefficient of single IgG macromolecules in an EWM, we use the size distribution of the solution filtered from aggregates, which manifests a 10 nm peak corresponding to IgG macromolecules, before (Figure 11b) and after shaking (Figure 11c). Furthermore, we measured the size distribution of 100-fold dilution of the initial IgG solution in the same EWM to determine the flotation coefficient for IgG aggregates (Figure 18).
Calculated similarly to what was described in Section 2.2, the flotation coefficients in the EWM have the following values. For single IgG molecules, we have Km = 3% (12–13 nm peak, as shown in Figure 11b,c); because for IgG aggregates, I1(a)/I0(a) = 2% (700–900 nm peak, as shown in Figures 11a and 15), we obtain Ka = I1(a)/I0(a) – 0.01 = 1% for aggregates. Thus, both Km and Ka in the EWM within the experimental error correspond to the usual 100-fold dilution, and the flotation effect does not manifest itself.
Figure 15
Figure 15. DLS intensity distribution over the particle sizes for 100-fold dilution of shaken IgG solution in an EWM (the initial concentration 3 × 1014 cm–3). Average total intensity (minus background scattering) Itot(173°) = 157 kcps (150 nm peak is 20%, and 750 nm peak is 80%).
2.6. Visualization of Floating Bubbles and Flotation Foam with a Transmission Optical Microscope
We studied the flotation process induced by shaking with the aid of a transmission microscope DigiMicro 2.0 (depth of field d = 7 mm). Figure 16a presents an example of IgG aqueous solution with the concentration of IgG molecules 3 × 1012 cm–3. It is seen that flotation foam is formed at the interface; this foam consists of numerous millimeter-sized bubbles, resulted from coalescence of smaller bubbles (see the pattern under the foam, where the bubbles with radii 10 < R < 100 μm are visible). Millimeter-sized bubbles disappear within ∼30 s after shaking. In Figure 16b, we give a pattern, obtained with pure water; the sizes of floating bubbles are approximately the same both in water and in aqueous IgG solution. As follows from the microscope images, the volume number density of micrometer-sized bubbles (averaged over the volume V = dS, where S is the frame area) for pure water (Figure 16b) is αbub ≈ 200 cm–3. Obviously, in the presence of IgG aggregates, the αbub value is much larger because these aggregates serve as microbubble nucleation centers.
Figure 16
Figure 16. Micrographs of gas bubbles in liquid samples, recorded immediately after shaking: (a) aqueous IgG solution with the concentration 3 × 1012 cm–3 and (b) pure water.
Figure 17a presents an image of water–ethanol IgG solution with a concentration of IgG molecules 3 × 1012 cm–3. It is seen that unlike the aqueous solution (cf. Figure 16a), in an EWM, flotation foam is practically absent. Figure 17b exhibits rising bubbles in a pure EWM, which is free of IgG particles. The radius of rising microbubbles lies in the range 30–200 μm, that is, they are larger than those in aqueous IgG solution. Note that in LPM experiments, carried out with IgG solution in an EWM, we did not see coarse particles, composed of gas bubbles and IgG aggregates, by contrast to aqueous IgG solution, see Figure 9. Thus, despite the visibility of rising bubbles, the flotation regime for IgG in an EWM essentially differs from that in aqueous solution.
Figure 17
Figure 17. Micrographs of gas bubbles in the samples, recorded immediately after shaking: (a) solution of IgG in an EWM with the concentration 3 × 1012 cm–3 and (b) pure ethanol.
3. Conclusions
Click to copy section linkSection link copied!
The study of shaking procedures has first shown that the aggregation of IgG molecules is enhanced. The aggregation proceeds more intensively in an EWM because of IgG denaturation as compared to water. Second, shaking induces flotation which is because of several complex factors. In aqueous solutions, there always exists an ion-stabilized nanobubble (bubston) phase: negative ions are adsorbed at the bubston interface, that is, its surface is electrically charged. As a consequence, foreign particles are attracted to the surface of bubstons because of the Coulomb monopole–dipole or positive–negative interaction; these particles can be monomeric IgG molecules, their aggregates, and also some solid impurity particles. However, bubstons have almost neutral buoyancy; therefore, the aggregates of bubstons with other particles cannot rise to the liquid surface. At the same time, macroscopically electroneutral micrbubbles with sizes of 10–100 μm are generated while shaking; these bubbles float to the surface because of Archimedean force. Microbubbles and nanobubbles attract suspended particles (IgG molecules and aggregates) with the formation of agglomerates that are transferred to the surface by larger bubbles (macrobubbles) because of nanobubble–macrobubble adhesion. Thus, bubstons serve as “spatial agents” (collectors) for flotation. At the same time, the content of ions in an EWM is essentially less compared to that in water, and this is why the ion-adsorption mechanism for the stabilization of nanobubbles probably does not act in an EWM, that is, the bubston phase cannot form. When shaking, macroscopic bubbles are also formed in an EWM, but these bubbles are almost electrically neutral, and therefore, Coulomb interaction between the bubbles and suspended particles is negligible. Meanwhile, there exists an alternative mechanism of adhesion to micro- and macrobubbles because of hydrophobic attraction; apparently, this mechanism should work equally in water and an EWM because it implies interaction of electrically neutral particles. This interaction is essentially short-range, and therefore, it can be ignored because of a relatively low concentration of floating bubbles (over ∼10 μm in size) obtained by shaking (∼103 cm–3 in water and even less in an EWM), while nanobubbles in water (whose concentration is high) cannot float up owing to their small size.
The considered flotation effect accompanying the shaking procedure leads to a significant discrepancy between the actual measured molecular concentrations and the dilution ratio, if an aliquot to be diluted is taken from the surface of the liquid. Taking into account the flotation effect, the maximum fraction of IgG macromolecules that can be transferred to a new liquid sample as a result of the dilution process with shaking is Km = 0.13. This efficiency is obviously limited by a small number of floating-up bubbles (∼103 cm–3) generated by the shaking procedure used by us per unit volume. In fact, the flotation coefficient could be much larger, reaching up to 100%, if shaking would generate so many floating-up bubbles that the distance between them would be comparable to their size. Thus, in multiple dilutions of IgG aqueous solution, the volume number density of IgG macromolecules decreases by at least the factor Kmn (n is the number of dilutions). If the flotation coefficient is assumed to be independent of the dilution number, for the initial volume number density of IgG macromolecules 3 × 1014 cm–3, we have the upper estimate (3 × 1014) × (0.13)n. For IgG aggregates, we obtained that a fraction of Ka = 0.05 is transferred into 100-fold dilution of shaken IgG aqueous solution, that is, the volume number density of IgG aggregates decreases with n-step dilution by at least the factor Kan = (0.05)n. Because the initial volume number density of IgG aggregates is 6 × 107 cm–3, it is clear that we cannot observe these aggregates for n > 4.
Summarizing, the calculation of the volume number density of particles in solutions of low and ultralow concentrations prepared using the technique of a multistage decrease in the concentration of a substance using shaking at each stage is not correct without considering the flotation effects. These effects may explain the results of studies proving the presence of nanoscale substances in solutions of ultralow concentrations, including those shown by us in the article. (45)
4. Materials
Click to copy section linkSection link copied!
Affinity-purified rabbit immunoglobulin G (IgG) dispersions in water and water–ethanol mixtures were used as test liquid samples. The initial liquid samples were purchased from AB Biotechnology Limited (UK, Edinburgh). Nanofiltration was used to remove impurity particles and viruses; the initial suspensions were first diluted in glycine buffer (pH = 7.2) up to a weight concentration of 0.125 mg/mL (3 × 1014 cm–3) and then sterilized by filtration through 0.22 μm syringe filters (Sartorius, Germany). SDS-PAGE electrophoresis and high-performance liquid chromatography–size exclusion chromatography technique were used to assess identity and purity (≥95%) of the samples prepared. For producing diluted samples, we used purified water produced using Milli-Q Integral 5 (Merck Millipore, France) with pH = 5.5 (water samples were saturated with atmospheric gases and contained dissolved CO2) or an EWM with an ethanol content of 36.7 vol % (Sigma-Aldrich, USA) and pH = 6.0. From the literature, the IEP of rabbit IgG pH = 8.61. (46)
5. Experimental Section
Click to copy section linkSection link copied!
5.1. Shaking and Dilution Procedures
Initial solutions of IgG in water and EWM were prepared in 20 mL borosilicate glass vials (Glastechnik Grafenroda, Germany) at room temperature without direct sunlight exposure by vortexing for 1 min at a frequency of 30 Hz and amplitude ∼1 mm to create a uniform distribution of particles throughout the volume using a Heidolph Multi Reax (545-10000-00) vortex mixer. For each measurement, an individual vial taken from a sterile factory packaging was used, and the pipettes were disposable. To study the disperse composition via DLS, 1.2 mL of the sample of each initial solution was poured into a 4.5 mL polystyrene square cuvette 10 × 10 × 45 mm (Sarstedt, Germany) for Malvern Zetasizer Nano use and hermetically sealed. Subsequently, the sample was shaken by oscillations in a vertical plane with an amplitude of 10 mm and a frequency of 5 Hz for 30 s to initiate the flotation process using an IKA orbital shaker, in which the platform was oriented vertically. It is important that shaking with such a large oscillation amplitude causes turbulent mixing of the solution with air from the free volume of the vial, resulting in the formation of a large amount of bubbles. To determine the number of protein particles carried to the surface of the sample because of shaking, we applied a 100-fold dilution procedure, which was as follows: 0.012 mL of the aliquot from the surface of the shaken solution and 1.188 mL of the diluent were mixed in one cuvette and then vortexed for homogenization.
5.2. Experimental Techniques
All samples were studied by three methods: DLS, LPM, and LPS. The DLS method allowed us to obtain the scattered light intensity distribution over the sizes of particles within the range of 1 to 105 nm from the time correlation function under the assumption that the particle shape is spherical. With the use of LPM, we can estimate the refractive index. LPM reliably determines the size of dispersed particles, whose size exceeds 100 nm. LPS measures the dependences of the scattering matrix on the scattering angle. DLS experiments were performed with a Zetasizer Nano ZS system (Malvern, UK) equipped with a continuous wave (CW) He–Ne laser at a wavelength of λ = 633 nm (maximum intensity 4 mW) and a temperature controller. Additionally, we used a Photocor-FC system (Photocor ltd, Russia) with second harmonic of CW YAG:Nd3+ laser (λ = 532 nm, maximum radiation power 40 mW) to verify the reproducibility of the peaks in size distributions of scattering intensity at different scattering angles and thus confirm their attribution to really existing particles and not to artifacts. The temperature of the samples was kept constant at 25 ± 0.5 °C. The autocorrelation function of scattering intensity was measured using a Zetasizer Nano ZS at an angle of 173° and using Photocor-FC at 30°.
For LPM, a semiconductor laser with a wavelength of λ = 405 nm was used. Drop samples of the studied liquids with a volume of 50 μL were placed on a mirror substrate, and then, a thin liquid layer formed from the spreading drop was examined by LPM. The phase microscope visualizes the spatial distribution of the phase shift between the interfering reference and object waves (for more detail, see ref (27)). In the presence of a particle in a liquid with a refractive index n, the phase shift changes by a value of
(1)
Here, n0 is the refractive index of the liquid and d is the particle size. If n > n0, then the profile of δ is a convex function across the particle and in the opposite case, it is a concave one. This allows the determination of the size and shape of inhomogeneities. In an LPS setup, the measurable scattering angles fall in the range of 0–160°. We do not provide a detailed description of the setup here; this is given in ref (30).
5.3. Instrumental Calibration
The DLS and LPM instruments were calibrated using monodisperse aqueous suspensions of polystyrene latex spheres (Sigma-Aldrich, USA) with average diameters d = 200 and 1200 nm and the refractive indices n = 1.59 and 1.62 for the wavelengths λ = 633 and 405 nm, respectively. Figure 18 shows the scattering intensity distribution over sizes of latex spheres in DLS experiments, which is normalized to the area under the curve.
Figure 18
Figure 18. DLS intensity distribution over the particle sizes in monodisperse aqueous suspensions of polystyrene latex spheres at a scattering angle of 173°: (a) d = 200 nm and (b) d = 1200 nm.
The LPM technique allows us to determine the phase shift profiles between the object and reference waves interfering after the passage of the object wave through a particle in the liquid sample. The value of δ is conventionally measured in λ/2 units, that is, in nanometers, see eq 1. Thus, the value actually measured in LPM is the OPD Δh, which for a spherical particle is expressed as (27,33)
(2)
Here, we introduced an apparatus coefficient γ, accounting for the diffraction distortion when measuring the spatial distribution of OPD on a submicron particle, in the geometric optics approximation γ = 2. The aim of calibration experiments was to determine the dependence of γ on the particle size in the 100–1000 nm size range. OPD measurements for latex particles are shown in Figure 19. The particle diameter is defined as the half-height of the OPD profile.
Figure 19
Figure 19. LPM images (2D distribution of OPD and the corresponding 1D profiles) of spherical polystyrene latex particles in monodisperse aqueous suspensions: (a,b) particle with d = 200 nm and (c,d) particle with d = 1200 nm.
As seen in Figure 19b, the particle size measured by LPM is ∼1.3 times larger than the size measured by DLS, see Figure 18a. This is explained by diffraction blurring for the particle sizes ∼λ/2. Bearing in mind the refractive index of polystyrene n = 1.62 (λ = 405 nm), we obtain γ = 1.7 for 200 nm particles. For 1200 nm particles, we have γ = 2.7; the particle profile has a plateau segment. Such a behavior is because the size of the particle exceeds the objective field depth (0.73 μm). The calibration curve is shown in Figure 20; the error bars display random scatter caused by interference noise and inaccurate focusing. This dependence was used to determine the refractive index of particles according to eq 2.
Figure 20
Figure 20. Dependence of the coefficient γ vs particle size.
The LPS setup was calibrated with the same latex solutions. For the sake of brevity, we do not present the calibration graphs for the scattering matrix elements here, but only note that because of the influence of stray reflections and scattering, the reliable scattering matrix measurements were restricted to the angles 0–90°.
6. Computational Methods
Click to copy section linkSection link copied!
6.1. Calculation of Scatterer Number Density
Below, we derive formulas for estimating the number of particles per unit volume of a liquid dispersion from scattering coefficient measurements. The scattering coefficient R(θ) (also called “the Rayleigh ratio”) is defined through the scattering intensity I(θ) as
where I0 is the intensity of the incident light, V is the scattering volume, and L is the distance from the center of the scattering volume to the observation point. Thus, the integral scattering coefficient is
where Ω is the solid angle, α = N/V is the volume number density of scatterers, and Csca is the scattering cross section of a single particle. We define the scattering indicatrix of a single particle as F(θ) = I1(θ)/I0, where I1(θ) is the scattering intensity of a single particle and the relationship 
should be met. Thus, we arrive at
(3)
(4)
should be met. Thus, we arrive at(5)
Following common practice, we use toluene (with known scattering coefficient) for calibration. The relationship between the scattering coefficients of the sample under study and toluene (R(θ) and RTol(θ)) is given as (47)
(6)
Here, I(θ) is the scattering intensity of the sample under study and ITol(θ) is the scattering intensity of toluene. Here, nsolv is the refractive index of the diluent, where the particles are suspended, and nTol is the refractive index of toluene. Finally, we refine the value of the volume number density of particles using the average scattering intensity at a fixed scattering angle and the total scattering cross section of a single particle
where ITol(173°) = 105 kcps, RTol(173°) = 22 × 10–6 cm–1, and nTol(λ = 0.633 μm) = 1.49.
(7)
Values of Csca and scattering indicatrix F(θ) were calculated using the program code developed by Mishchenko for spherical particles. (40)
6.2. Theoretical Approximation of Scattering Matrices for IgG Dispersions
An approximate structural model of IgG dispersions constructed on the basis of DLS and LPM data, that is, the number of different types of particles found and the measured values of their sizes and refractive indices are used as a priori information to solve the inverse problem for the scattering matrix measured by LPS. Ultimately, the solution of such an inverse problem refines and supplements the structural model.
To confirm the aggregative nature of the submicron particles observed in IgG dispersions, we theoretically modeled the scattering matrix for a system containing IgG aggregates, considered as fractal clusters of IgG macromolecules. The theoretical scattering matrices of IgG dispersions were approximated by a weighted sum of matrices Fij(p) (θ) calculated for a model of spherical particles of several types: monomeric particles with the diameter d = 12 nm, bubstons with d = 250 nm, and IgG aggregates with the average diameter ⟨d⟩ = 350 nm and the distribution width 200–500 nm, as follows
(8)
where p is the type of particles, αp stands for the volume number density of particles of the corresponding type (e.g., for IgG monomers and aggregates, αp = 2.5 × 1014 cm–3 and 5.4 × 107 cm–3, while for bubstons in water, αp ≈ 106 cm–3, see ref (26)), Cpsca is the scattering cross section, and Fij(p) are the matrix elements of the pth type of particles. The total number of the types of model particles is 14; 12 of them are related to aggregates with gyration radii 100–2000 nm. While calculating eq 9, we assume that the values of F12(θ), F34(θ), and F44(θ) for the monomers coincide with the corresponding elements of the Rayleigh scattering matrix (dashed curves) because the monomers in aggregates are much smaller than those in the radiation wavelength. The values of the element F11(θ) and the scattering cross sections for the IgG aggregates were calculated in the Rayleigh–Hans–Debye approximation. If the condition qRg > 1 is met for a cluster, F11 is described by
where 
is the modulus of the scattering vector, Df is the fractal dimension of the cluster, and Rg is the gyration radius of the cluster. (41)
(9)
is the modulus of the scattering vector, Df is the fractal dimension of the cluster, and Rg is the gyration radius of the cluster. (41)Author Information
Click to copy section linkSection link copied!
- Nikolai F. Bunkin - Bauman Moscow State Technical University, 2-nd Baumanskaya str. 5, Moscow 105005, Russia; Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, Russia;
http://orcid.org/0000-0002-6893-1739;
- Nikita V. Penkov - Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, Institutskaya str. 3, Pushchino 142290, Moscow region, Russia;http://orcid.org/0000-0003-2212-5640
- Sergey V. Gudkov - Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, Russia;http://orcid.org/0000-0002-8814-6906
Acknowledgments
Click to copy section linkSection link copied!
This work was supported by the research project “Physical Methods in Agriculture and Ecology” and the MEPhI Academic Excellence Project, contract no. 02.a03.21.0005. Part of the work related to studying the properties of protein aggregates was supported by the Russian Foundation for Basic Research (20-34-70037). Part of the work related to the methods for characterization of nano-objects was supported by the grant from the Presidential Council for state support of young Russian scientists (MD-2128.2020.11). The authors are grateful to the Center for Collective Use of GPI RAS for the equipment provided.
References
Click to copy section linkSection link copied!
This article references 47 other publications.
- 1Gudkov, S. V.; Lyakhov, G. A.; Pustovoy, V. I.; Shcherbakov, I. A. Influence of Mechanical Effects on the Hydrogen Peroxide Concentration in Aqueous Solutions. Phys. Wave Phenom. 2019, 27, 141– 144, DOI: 10.3103/s1541308x19020092Google ScholarThere is no corresponding record for this reference.
- 2Lee, J. K.; Walker, K. L.; Han, H. S.; Kang, J.; Prinz, F. B.; Waymouth, R. M.; Nam, H. G.; Zare, R. N. Spontaneous generation of hydrogen peroxide from aqueous microdroplets. Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 19294– 19298, DOI: 10.1073/pnas.1911883116Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVGgu7nP&md5=6e4ea4b03c9ee031c2344d9da262e1a2Spontaneous generation of hydrogen peroxide from aqueous microdropletsLee, Jae Kyoo; Walker, Katherine L.; Han, Hyun Soo; Kang, Jooyoun; Prinz, Fritz B.; Waymouth, Robert M.; Nam, Hong Gil; Zare, Richard N.Proceedings of the National Academy of Sciences of the United States of America (2019), 116 (39), 19294-19298CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)We show H2O2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1μm to 20μm in diam.). Prodn. of H2O2, as assayed by H2O2-sensitive fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H2O2. The generated H2O2 concn. was ≈30μM (≈1 part per million) as detd. by titrn. with potassium titanium oxalate. Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets, indicating that pure water microdroplets directly generate H2O2 without help from O2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H2O2 formation and report a no. of different expts. exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH- at or near the surface of the water microdroplet. This catalyst-free and voltage-free H2O2 prodn. method provides innovative opportunities for green prodn. of hydrogen peroxide.
- 3Rieth, M.; Kempf, A. M.; Stein, O. T.; Kronenburg, A.; Hasse, C.; Vascellari, M. Evaluation of a flamelet/progress variable approach for pulverized coal combustion in a turbulent mixing layer. Proceedings of the Combustion Institute 2019, 37, 2927– 2934, DOI: 10.1016/j.proci.2018.05.150Google Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsVejtb3N&md5=b1892a4f858ba8ed15befb115189762fEvaluation of a flamelet/progress variable approach for pulverized coal combustion in a turbulent mixing layerRieth, Martin; Kempf, Andreas M.; Stein, Oliver T.; Kronenburg, Andreas; Hasse, Christian; Vascellari, MicheleProceedings of the Combustion Institute (2019), 37 (3), 2927-2934CODEN: PCIRC2; ISSN:1540-7489. (Elsevier B.V.)A steady flamelet/progress variable (FPV) approach for pulverized coal flames is employed to simulate coal particle burning in a turbulent shear and mixing layer. The configuration consists of a carrier-gas stream of air laden with coal particles that mixes with an oxidizer stream of hot products from lean combustion. Carrier-phase DNS (CP-DNS) are performed, where the turbulent flow field is fully resolved, whereas the coal is represented by Lagrangian point particles. CP-DNS with direct chem. integration is performed first and provides state-of-the-art validation data for FPV modeling. In a second step the control variables for FPV are extd. from the CP-DNS and used to test if the tabulated manifold can correctly describe the reacting flow (a priori anal.). Finally a fully coupled a posteriori FPV simulation is performed, where only the FPV control variables are transported, and the chem. state is retrieved from the table and fed back to the flow solver. The a priori results show that the FPV approach is suitable for modeling the complex reacting multiphase flow considered here. The a posteriori data is similarly in good agreement with the ref. CP-DNS, although stronger deviations than a priori can be obsd. These discrepancies mainly appear in the upper flame (of the present DNS), where premixing and highly unsteady extinction and re-ignition effects play a role, which are difficult to capture by steady non-premixed FPV modeling. However, the present FPV model accurately captures the lower, more stable flame that burns in non-premixed mode.
- 4Nada, M. H.; Gillan, E. G.; Larsen, S. C. Mechanochemical reaction pathways in solvent-free synthesis of ZSM-5. Microporous Mesoporous Mater. 2019, 276, 23– 28, DOI: 10.1016/j.micromeso.2018.09.009Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvVeqsrvJ&md5=480aac46fb4d298676751e8fc873916bMechanochemical reaction pathways in solvent-free synthesis of ZSM-5Nada, Majid H.; Gillan, Edward G.; Larsen, Sarah C.Microporous and Mesoporous Materials (2019), 276 (), 23-28CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Solvent-free methods for the synthesis of ZSM-5 have been previously reported in the literature. These methods typically involve grinding the starting materials together prior to the hydrothermal reaction step. However, very little is known about the reaction intermediates formed during the mechanochem. pre-reaction or about how the pre-reaction impacts the subsequent hydrothermal synthesis conditions (temp. and length of hydrothermal treatment). In this study, the solvent-free synthesis of ZSM-5 was investigated while varying the length and type of grinding (manual, ball-mill) and the components of the reaction mixt. The initial reactions that occurred between the solid-state raw materials during grinding were monitored by powder X-ray diffraction (pXRD). Extended grinding initiates exchange reactions between several reagents to form NaCl and to liberate ammonia and water. The resulting wet paste undergoes facile thermal conversion to cryst. zeolite ZSM-5 framework structures. These results provide valuable insights used to guide the optimization of the synthesis conditions required to prep. stable, cryst. and high surface area ZSM-5 under solvent-free synthesis conditions. The solvent-free approach contributes to the overall goal of a greener, more sustainable ZSM-5 synthesis.
- 5Belhouchet, H.; Sahraoui, T.; Belhouchet, K.; Romero, M. Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powder. J. Aust. Ceram. Soc. 2019, 55, 135– 144, DOI: 10.1007/s41779-018-0219-yGoogle Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFGrurrL&md5=230ddd6c64fd74d6be33d497dff7f761Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powderBelhouchet, Hocine; Sahraoui, Toufik; Belhouchet, Khaled; Romero, MaximinaJournal of the Australian Ceramic Society (2019), 55 (1), 135-144CODEN: JACSGZ; ISSN:2510-1579. (Springer)In this work, the effect of heating rate and mech. activation on the reaction of kaolin and aluminum powder was investigated. A batch comprised of 89.5 wt% kaolin and 10.5 wt% aluminum powders was mixed and milled in a planetary ball-mill for 1, 5, 10, 20 and 40 h. The mixt. powders were heat treated with a heating rate of 5, 10, 15, 20, 30 and 40 °C/min, resp. After milling for 20 and 40 h, the results showed the formation of free silicon, quartz and nacrite (Al2Si2(OH)4) at room temp. The kaolinite dehydroxylation, aluminum oxidn. and the θ- to α-Al2O3 transformations are highly affected by heating rate and mech. activation. As compared with the smallest heating rate, the mixts. heated with faster heating rate show the disappearance of the peak corresponding to the oxidn. of aluminum and the appearance of a second peak corresponding to the formation of α-Al2O3. The intensity of the last peak increases with increasing of the heating rate and milled at lower milling time. The effects of heating rate in the reaction of kaolin and aluminum powder are attributed to the amorphization of kaolinite, the diffusion of Al3+ to form an amorphous alumina layer on the particle surface and the generation of microcracks at the particle surface of aluminum powder.
- 6European Directorate for the Quality of Medicines & HealthCare. European Pharmacopoeia, 9th Edition, Suppl. 9.3; Council of Europe: Strasbourg, 2017.Google ScholarThere is no corresponding record for this reference.
- 7Banga, A. K. Therapeutic Peptides and IgGs: Formulation, Processing, and Delivery Systems; CRC Press: Boca Raton, 2015.Google ScholarThere is no corresponding record for this reference.
- 8Wang, W.; Roberts, C. J. Aggregation of therapeutic IgGs; John Wiley & Sons, Inc.: Hoboken, New Jersey, 2010.Google ScholarThere is no corresponding record for this reference.
- 9Joubert, M. K.; Luo, Q.; Nashed-Samuel, Y.; Wypych, J.; Narhi, L. O. Classification and Characterization of Therapeutic Antibody Aggregates. J. Biol. Chem. 2011, 286, 25118, DOI: 10.1074/jbc.m110.160457Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXosFGmt7g%253D&md5=ec705e8e509fabf4ccd1d7a31083ad02Classification and Characterization of Therapeutic Antibody AggregatesJoubert, Marisa K.; Luo, Quan-Zhou; Nashed-Samuel, Yasser; Wypych, Jette; Narhi, Linda O.Journal of Biological Chemistry (2011), 286 (28), 25118-25133CODEN: JBCHA3; ISSN:0021-9258. (American Society for Biochemistry and Molecular Biology)A host of diverse stress techniques was applied to a monoclonal antibody (IgG2) to yield protein particles with varying attributes and morphologies. Aggregated solns. were evaluated for percent aggregation, particle counts, size distribution, morphol., changes in secondary and tertiary structure, surface hydrophobicity, metal content, and reversibility. Chem. modifications were also identified in a sep. report. Aggregates were categorized into seven discrete classes, based on the traits described. Several addnl. mols. (from the IgG1 and IgG2 subtypes as well as i.v. IgG) were stressed and defined with the same classification system. The mechanism of protein aggregation and the type of aggregate formed depends on the nature of the stress applied. Different IgG mols. appear to aggregate by a similar mechanism under the same applied stress. Aggregates created by harsh mech. stress showed the largest no. of subvisible particles, and the class generated by thermal stress displayed the largest no. of visible particles. Most classes showed a disruption of the higher order structure, with the degree of disorder depending on the stress process. Particles in all classes (except thermal stress) were at least partially reversible upon diln. in pH 5 buffer. High copper content was detected in isolated metal-catalyzed aggregates, a stress previously shown to produce immunogenic aggregates. In conclusion, protein aggregates can be a very heterogeneous population, whose qualities are the result of the type of stress that was experienced.
- 10Evdokimov, I. A.; Titov, S. A.; Titov, S. A.; Polyansky, K. K.; Saiko, D. S. Ultrafiltration concentrating of curd whey after electroflotation treatment. Foods Raw Mater. 2017, 5, 131– 136, DOI: 10.21179/2308-4057-2017-1-131-136Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXls1Sksbo%253D&md5=b5405d24e531290f349eeb6b14949155Ultrafiltration concentrating of curd whey after electroflotation treatmentEvdokimov, I. A.; Titov, S. A.; Polyansky, K. K.; Saiko, D. S.Foods and Raw Materials (2017), 5 (1), 131-136CODEN: FRMOA6; ISSN:2310-9599. (Kemerovo Technological Institute of Food Industry)This work offers a view on the outcomes of a study focusing on ultrafiltration of curd whey treated on the basis of the membrane electroflotation method in order to ensure more complete extn. of whey proteins when processing recoverable dairy crude. The feature that makes the method different is the presence of membranes between the anode and the cathode while the machines for membrane electroflotation are designed so that current does not run through the whey. To det. the element compn. of whey prior to and after electroflotation the method of electron probe X-ray microanal. was used. It has been shown that the filtration rate of whey treated through electroflotation nearly doubles up if compared to the initial rate. There has also been detected the dependence related to the impact that the concn. of solids and the pressure have on the filtration rate; besides, the kinetics of the ultrafiltration process has been investigated. The method of electron probe X-ray microanal. was employed to study the element compn. of whey both before and after the electroflotation treatment. The increase in the whey ultrafiltration rate after electroflotation can be explained by a growing Hydrogen index and a reduced concn. of Calcium after electroflotation. Besides, a quant. phys. model of whey ultrafiltration was developed, which takes into view specific features of polarization layer formation. The model implies conditional division of whey flow at the membrane surface into two streams - a normal one and a tangential one. Part of the protein mols. transported by the normal flow settles on the membrane surface while the other part of them remains near the surface up until it is pushed into the whey bulk by protein mols. of the tangential flow. That all mentioned above fixes certain elements of newness in the field of membrane technologies. The study was performed at the Voronezh State University of Engineering Technologies and the North Caucasus Federal University (Russian Federation).
- 11Yoon, R.-H. The role of hydrodynamic and surface forces in bubble–particle interaction. Int. J. Min. Process 2000, 58, 128– 143, DOI: 10.1016/s0301-7516(99)00071-xGoogle ScholarThere is no corresponding record for this reference.
- 12Ralston, J.; Fornasiero, D.; Hayes, R. Bubble–particle attachment and detachmentin flotation. Int. J. Min. Process 1999, 56, 133– 164, DOI: 10.1016/s0301-7516(98)00046-5Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXjsFKlsrc%253D&md5=d263d53f2b566cb854a1282b05998b82Bubble-particle attachment and detachment in flotationRalston, John; Fornasiero, Daniel; Hayes, RobertInternational Journal of Mineral Processing (1999), 56 (1-4), 133-164CODEN: IJMPBL; ISSN:0301-7516. (Elsevier Science B.V.)The mechanism by which particles and bubbles interact captures many of the central concepts of colloid science and hydrodynamics and is an example of heterocoagulation. Hydrodynamics, interfacial (including capillary) forces, particle and bubble behavior and soln. chem. are all interwoven. The processes of attachment and detachment are focused upon here. The identification is considered of a flotation 'domain', the deformation of a bubble surface upon interaction with a solid surface, the kinetics of three phase contact line expansion and the detn. of attachment efficiencies through to the direct measurement of bubble-particle interaction forces. The results, concepts, and implications of this work are discussed.
- 13Rubio, J.; Capponi, F.; Matiolo, E.; Nunes, D.; Guerrero, C. P.; Berkowitz, G. Advances in flotation of mineral fines. Proceedings XXII International Mineral Processing Congress (IMPC) , 2003; pp 1014– 1022.Google ScholarThere is no corresponding record for this reference.
- 14Fuerstenau, M. C.; Yoon, R. H.; Jameson, G. J. Froth Flotation: A Century of Innovation; Society for Mining, Metallurgy, and Exploration, 2007.Google ScholarThere is no corresponding record for this reference.
- 15Sobhy, A.; Tao, D. Nanobubble column flotation of fine coal particles and associated fundamentals. Int. J. Min. Process. 2013, 124, 109– 116, DOI: 10.1016/j.minpro.2013.04.016Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXotlOrsr4%253D&md5=a13eff3717072926caf3499e97f5eff0Nanobubble column flotation of fine coal particles and associated fundamentalsSobhy, A.; Tao, D.International Journal of Mineral Processing (2013), 124 (), 109-116CODEN: IJMPBL; ISSN:0301-7516. (Elsevier B.V.)Froth flotation is a widely used, cost effective particle sepn. process. However, its high performance is limited to a narrow particle size range between approx. 50 to 600 μm for coal and 10 to 100 μm for minerals. Outside this range, the efficiency of froth flotation decreases significantly, esp. for difficult-to-float particles of weak hydrophobicity (e.g., oxidized coal).This study was aimed at enhancing recovery of an Illinois fine coal sample using a specially designed flotation column featuring a hydrodynamic cavitation nanobubble generator. Nanobubbles that are mostly smaller than 1 μm can be formed selectively on hydrophobic coal particles from dissolved air in coal slurry. Results indicate that the combustible recovery of a - 150 μm coal increased by 5-50% in the presence of nanobubbles, depending on process operating conditions. Nanobubbles also significantly improved process sepn. efficiency. Other major advantages of the nanobubble flotation process include lower frother dosage and air consumption since nanobubbles are produced from air naturally dissolved in water, thereby resulting in considerably lower operating costs.
- 16Ahmadi, R.; Khodadadi, D. A.; Abdollahy, M.; Fan, M. Nano-microbubble flotation of fine and ultrafine chalcopyrite particles. Int. J. Min. Sci. Technol. 2014, 24, 559– 566, DOI: 10.1016/j.ijmst.2014.05.021Google ScholarThere is no corresponding record for this reference.
- 17Calgaroto, S.; Azevedo, A.; Rubio, J. Flotation of quartz particles assisted by nanobubbles. Int. J. Min. Process. 2015, 137, 64– 70, DOI: 10.1016/j.minpro.2015.02.010Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXjtFGhu70%253D&md5=c94d209077569420ddeb5ad1f00b268bFlotation of quartz particles assisted by nanobubblesCalgaroto, S.; Azevedo, A.; Rubio, J.International Journal of Mineral Processing (2015), 137 (), 64-70CODEN: IJMPBL; ISSN:0301-7516. (Elsevier B.V.)Exptl. studies of flotation of quartz particles, under various conditions and cells (setups), are presented. Pure and well-characterized quartz samples were treated with a com. alkyl ether monoamine as flotation collector with bubbles in various sizes: coarse bubbles (400-800 μm); nanobubbles (200-720 nm); and their mixts. The nanobubbles were generated by selective sepn. from microbubbles, which are formed together after depressurizing-cavitation of the satd. water in air (as in pressure flotation or dissolved air flotation), at 66.1 psi satn. pressure. Flotation with single nanobubbles was not effective due to their very low lifting power or practically nil buoyancy. Yet, size-by-size flotation recoveries with coarse plus nanobubbles, compared with coarse bubbles, enhanced by 20-30 % the very fine quartz fractions by 20-30% (8-74 μm; Sauter diam.-D32) and slightly lowered the recoveries of coarse particles (67-118 μm; D32 diam.). Flotation of quartz samples (composites) having wide particle size distribution and results in a mech. cell validated the overall recovery enhancement of the fines. Fine particle capture (nanobubbles enhanced the contact angle of quartz) and aggregation of the quartz ultrafines (proved with micrographs) by the nanobubbles are the main mechanisms responsible for the higher recoveries. The effect on flotation of the coarser quartz fractions, at bench scale, may be explained in terms of a reduced rising velocity of the coarse bubbles, in the presence of nanobubbles, decreasing the degree of bubble carryover. It is expected that the use of collector-coated nanobubbles (tailor-made "bubble-collectors" and flocculants) will broaden options in fine mineral flotation. The future sustainable forms (cheaply produced) of nanobubble generation on a large scale and their injection in cells are envisaged.
- 18Azevedo, A.; Etchepare, R.; Calgaroto, S.; Rubio, J. Aqueous dispersions of nanobubbles: generation, properties and features. Miner. Eng. 2016, 94, 29– 37, DOI: 10.1016/j.mineng.2016.05.001Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XovFWnurc%253D&md5=862d23ced08a777be8de2e9798e3747cAqueous dispersions of nanobubbles: Generation, properties and featuresAzevedo, A.; Etchepare, R.; Calgaroto, S.; Rubio, J.Minerals Engineering (2016), 94 (), 29-37CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)Nanobubbles (NBs) have interesting and peculiar properties such as high stability, longevity and high surface area per vol., leading to important applications in mining-metallurgy and environmental areas. NBs are also of interest in interfacial phenomena studies involving long-range hydrophobic attraction, microfluidics, and adsorption at hydrophobic surfaces. However, little data are available on effective generation of concd. NBs water dispersions and on their physicochem. and interfacial properties. In this work, air was dissolved into water at pH 7 and different pressures, and a flow was depressurized through a needle valve to generate 150-200 nm (mean diam.) NBs and MBs-microbubbles (about 70 μm). Microphotographs of the NBs were taken only in the presence of blue methylene dye as the contrast medium. Main results showed that a high concn. of NBs (no. per vol.) was obtained by decreasing the satn. pressure and surface tension. The no. of NBs, at 2.5 bar, increased from 1.0 × 108 NB mL-1 at 72.5 mN m-1 to 1.6 × 109 NB mL-1 at 49 mN m-1 (100 mg L-1 α-Terpineol). The NBs mean diam. and concn. only slightly varied within 14 days, which demonstrates the high stability of these highly concd. NBs aq. dispersions. Finally, after the NBs were attached to the surface of a grain of pyrite (fairly hydrophobic mineral), the NBs dramatically increased the population of MBs, which shows the enhancement of particle hydrophobicity due to NBs adhesion. The results were explained in terms of interfacial phenomena and it is believed that these tiny bubbles, dispersed in water at high concns., will lead to cleaner and more sustainable mineral flotation.
- 19Etchepare, R.; Oliveira, H.; Nicknig, M.; Azevedo, A.; Rubio, J. Nanobubbles: Generation using a multiphase pump, properties and features in flotation. Miner. Eng. 2017, 112, 19– 26, DOI: 10.1016/j.mineng.2017.06.020Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFCrsLrO&md5=a6a5b2c60e31a3276900209bd00513ceNanobubbles: Generation using a multiphase pump, properties and features in flotationEtchepare, Ramiro; Oliveira, Henrique; Nicknig, Marcio; Azevedo, Andre; Rubio, JorgeMinerals Engineering (2017), 112 (), 19-26CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)The importance of nanobubbles is now widely known, particularly their applications and potential in mineral processing. The actual challenge is to generate a high concn. of bubbles (no. per water vol.) in a sustainable manner at high flow rates. The main objective of this work was to develop a new method for generating highly-loaded nanobubbles aq. solns. by hydrodynamic cavitation using a centrifugal multiphase pump (CMP) and a needle valve. Nanobubbles (150-200 nm) were formed, at 22°C, with the pump and a recycle column, at various operating pressures and air/liq. surface tension. Nanobubbles were resistant to shearing caused by pump impellers and to high operating pressures (up to 5 bar) throughout several bubble generation cycles. The size of the nanobubbles remained const., and their numeric concn. increased as a function of these cycles, reaching equil. after 29 cycles; this was dependent on pump pressure and the surface tension of the soln. The highest concn. (4 × 109 nanobubbles mL-1) was obtained at 5 bar and 49 mN m-1 surface tension (air holdup = 6.8% and D32 of microbubbles in the range between 62 and 70μm). These phenomena can be explained by Henry's Law and the lower energy required for bubble formation when the interfacial tension (air/water) decreases and when the differential pressure in the cavitation zone increases. The mean diam. and concn. of these nanobubbles did not vary significantly over a period of two months, demonstrating the high stability of these concd. nanobubbles. It is concluded that the procedure has great potential in future applications in ore flotation and wastewater treatment and reuse.
- 20Rosa, A. F.; Rubio, J. On the role of nanobubbles in particle–bubble adhesion for the flotation of quartz and apatitic minerals. Miner. Eng. 2018, 127, 178– 184, DOI: 10.1016/j.mineng.2018.08.020Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsFGqsb%252FK&md5=ad7cee54d8b5557c3ca38e0b34a40a2eOn the role of nanobubbles in particle-bubble adhesion for the flotation of quartz and apatitic mineralsRosa, A. F.; Rubio, J.Minerals Engineering (2018), 127 (), 178-184CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)This work evaluated the influence of nanobubbles (150-200 nm, mean diam.) on the visual adhesion of microbubbles (70 μm mean diam.) and macrobubbles (1 mm mean diam.) onto selected mineral particles (quartz and apatite) and on the flotation of both minerals, at bench scale. The adhesion of bubbles to high purity grains of quartz and apatite was monitored using a specially designed photog. technique. The results showed that the highest adhesion of bubbles onto the mineral grains occurred only after "conditioning" with nanobubbles. The nanobubbles appear to adhere to hydrophobic surfaces and confined to the rough surfaces of the grains, probably due to the dissipation of the free surface energy of the solids. As a result, the nanobubbles appear to serve as nuclei for enhanced adhesion of micro and/or macrobubbles, assisting the flotation of both minerals. In the case of quartz (D50 = 290 μm), the recovery increase was about 23% compared to a std. test of flotation with macrobubbles only. Furthermore, flotation kinetics was rapid and quartz recovery, at the first min, was double that obtained in the absence of nanobubbles. In the case of a fine apatitic ore (35% < 37 μm particles), best results were obtained with a combination of nano, micro and macrobubbles, with a 500-1000 g t-1 sapond. soybean oil collector and a 300-600 g t-1 gelatinized corn starch depressant of iron bearing minerals. The P2O5 recoveries increased about 9% compared to flotation with macrobubbles only, and sepn. also occurred at a higher rate. The total recovered phosphate (4 min std. test) was obtained in the first 1.5 min, after conditioning with nanobubbles, followed by injection of and microbubbles. Results validated the reported high potential for nanobubbles in "surface conditioning", the first stage of mineral flotation and were explained in terms of the soln. and interfacial phenomena involved.
- 21Craig, V. S. J.; Ninham, B. W.; Pashley, R. M. Effect of Electrolytes on bubble coalescence. Nature 1993, 364, 317– 319, DOI: 10.1038/364317a0Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXlsVOis7s%253D&md5=afddda175536ac1b0bd7645c677cf7e1Effect of electrolytes on bubble coalescenceCraig, V. S. J.; Ninham, B. W.; Pashley, R. M.Nature (London, United Kingdom) (1993), 364 (6435), 317-19CODEN: NATUAS; ISSN:0028-0836.The foaminess of ocean waves, relative to fresh water, has long been attributed to the effect of salts in reducing bubble coalescence. This phenomenon is exploited in extn. processes using froth flotation, in which the extn. efficiency increases as the bubble size gets smaller. But whereas the bubble-stabilizing effect of surfactants is well understood, the effect of salts is not; the fact that salts decrease the surface tension of water and that they are desorbed from the air-water interface would, if anything, be expected to destabilize bubbles. Here the authors report the results of expts. conducted to study the stabilization of bubbles by salts. Bubble coalescence is inhibited by some salts whereas others have no effect and this inhibition occurs only upon the matching of a 2-valued empirical property assigned to each anion and cation. The authors believe these observations can be explained only by the local influence of the ions on water structure, possibly in a way related to the hydrophobic interaction.
- 22Craig, V. S. J.; Ninham, B. W.; Pashley, R. M. The Effect of Electrolytes on Bubble Coalescence in Water. J. Phys. Chem. 1993, 97, 10192– 10197, DOI: 10.1021/j100141a047Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXlvV2ls70%253D&md5=7ce7bbd1b65258b7352efabadbeee696The effect of electrolytes on bubble coalescence in waterCraig, Vincent S. J.; Ninham, Barry W.; Pashley, Richard M.Journal of Physical Chemistry (1993), 97 (39), 10192-7CODEN: JPCHAX; ISSN:0022-3654.Common electrolytes were found either to reduce the rate of bubble coalescence in water or to produce no effect. For a range of cations and anions, a system of combining rules emerges that characterizes the behavior of all the salts studied. The specific effects of electrolytes on bubble coalescence may be related to their effect on water structure and hence the hydrophobic interaction. The phenomenon may have applications in various fields, including decompression sickness, hydrophobic chromatog., and possibly biol. and evolution.
- 23Henry, C. L.; Craig, V. S. J. Inhibition of Bubble Coalescence by Osmolytes: Sucrose, Other Sugars, and Urea. Langmuir 2009, 25, 11406– 11412, DOI: 10.1021/la9015355Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXotVGktLo%253D&md5=cb1a4903a645e7b6ec7a9bbeee702439Inhibition of Bubble Coalescence by Osmolytes: Sucrose, Other Sugars, and UreaHenry, Christine L.; Craig, Vincent S. J.Langmuir (2009), 25 (19), 11406-11412CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Bubble coalescence inhibition by non-surface-active, nonelectrolytes urea and sucrose, and other small sugars, in aq. soln. is reported. Urea has no effect on bubble stability up to high concns. > 1 M, while sucrose inhibits coalescence in the range 0.01-0.3 M, similar to inhibiting electrolytes. Urea and sucrose both increase bubble coalescence inhibition in inhibiting and noninhibiting electrolytes in a cooperative manner, but urea decreases the efficacy of sucrose in mixed solns. Several mono- and disaccharides also inhibit bubble coalescence at ∼ 0.1 M, and the sugars vary in effectiveness. Disaccharides are more effective than the sum of their individual monosaccharide constituents, and sugars with very similar structures (for instance, diastereomers galactose and mannose) can show large differences in coalescence inhibition and hence thin film stability. Then it was concluded that solute charge is not required for bubble coalescence inhibition, which indicates that the mechanism is not one of electrostatic surface repulsion and instead an effect on dynamic film thinning other than Gibbs-Marangoni elasticity is implicated. Solute structure is important in detg. coalescence.
- 24Horn, R. G.; Ninham, B. W. Experimental studies of solvation forces in Micellar Solutions and Microemulsions. In Micellar Solutions and Microemulsions; Chen, S. H., Rajagopalan, A., Eds.; Springer-Verlag: New York; Chapter 5, 1990.Google ScholarThere is no corresponding record for this reference.
- 25Pashley, R. M.; Ninham, B. W. Double-layer forces in ionic micellar solutions. J. Phys. Chem. 1987, 91, 2902– 2904, DOI: 10.1021/j100295a049Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXitVagu7c%253D&md5=8ec962fb205255db856902ce3942b5a6Double-layer forces in ionic micellar solutionsPashley, R. M.; Ninham, B. W.Journal of Physical Chemistry (1987), 91 (11), 2902-4CODEN: JPCHAX; ISSN:0022-3654.Measurements are reported of the force between 2 mol. smooth mica surfaces coated with adsorbed bilayers of CTAB and sepd. by an aq. soln. of CTAB. Below the crit. micelle concn. (cmc), the double layer forces are well described by assuming the surfactant to be a completely dissocd. simple 1:1 electrolyte. Above the cmc, micelles and their "bound" counterions do not contribute to the Debye length. Some consequences for colloid stability are discussed.
- 26Fang, Z.; Wang, X.; Zhou, L.; Zhang, L.; Hu, J. Formation and Stability of Bulk Nanobubbles by Vibration. Langmuir 2020, 36, 2264– 2270, DOI: 10.1021/acs.langmuir.0c00036Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXjs1KnsL4%253D&md5=c6246df18f3d01821cfb51d0e8cfb650Formation and Stability of Bulk Nanobubbles by VibrationFang, Zhou; Wang, Xingya; Zhou, Limin; Zhang, Lijuan; Hu, JunLangmuir (2020), 36 (9), 2264-2270CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Vibration is a very common process in nature, industry, biol., etc. Thus, whether vibration could induce the formation of nanoscale bubbles in water or not is very important for some chem. or biol. reactions. In this paper, we designed a control expt. to simulate the vibration process to explore the prodn. and stability of bulk nanobubbles. Exptl. results showed that the vibration could indeed induce the formation of a certain no. of bulk nanobubbles in water. In addn., the formation of bulk nanobubbles depended on the frequency and time of vibration. The existence of gas-liq. interface played an important role for the bulk nanobubbles formation because that external air is a possible important gas source. Our findings would be helpful to explore the mystical behavior of nanobubbles in natural processes.
- 27Bunkin, N. F.; Shkirin, A. V.; Suyazov, N. V.; Babenko, V. A.; Sychev, A. A.; Penkov, N. V.; Belosludtsev, K. N.; Gudkov, S. V. Formation and Dynamics of Ion-Stabilized Gas Nanobubble Phase in the Bulk of Aqueous NaCl Solutions. J. Phys. Chem. B 2016, 120, 1291– 1303, DOI: 10.1021/acs.jpcb.5b11103Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVKiu7w%253D&md5=f7592b4ca20949b5aaaa942eb276828aFormation and Dynamics of Ion-Stabilized Gas Nanobubble Phase in the Bulk of Aqueous NaCl SolutionsBunkin, Nikolai F.; Shkirin, Alexey V.; Suyazov, Nikolay V.; Babenko, Vladimir A.; Sychev, Andrey A.; Penkov, Nikita V.; Belosludtsev, Konstantin N.; Gudkov, Sergey V.Journal of Physical Chemistry B (2016), 120 (7), 1291-1303CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)Ion-stabilized gas nanobubbles (the so-termed "bubstons") and their clusters are investigated in bulk aq. solns. of NaCl at different ion concns. by four independent laser diagnostic methods. It turned out that in the range of NaCl concn. 10-6 < C < 1 M the radius of bubston remains virtually unchanged at a value of 100 nm. Bubstons and their clusters are a thermodynamically nonequil. phase, which has been demonstrated in expts. with magnetic stirrer at different stirring rates. Different regimes of the bubston generation, resulting from various techniques of processing the liq. samples, were explored.
- 28Yurchenko, S. O.; Shkirin, A. V.; Ninham, B. W.; Sychev, A. A.; Babenko, V. A.; Penkov, N. V.; Kryuchkov, N. P.; Bunkin, N. F. Ion-Specific and Thermal Effectsin the Stabilization of the Gas NanobubblePhase in Bulk Aqueous Electrolyte Solutions. Langmuir 2016, 32, 11245– 11255, DOI: 10.1021/acs.langmuir.6b01644Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtVKisrnN&md5=8ad80ac979799820fb1a360f9a6c19a5Ion-Specific and Thermal Effects in the Stabilization of the Gas Nanobubble Phase in Bulk Aqueous Electrolyte SolutionsYurchenko, Stanislav O.; Shkirin, Alexey V.; Ninham, Barry W.; Sychev, Andrey A.; Babenko, Vladimir A.; Penkov, Nikita V.; Kryuchkov, Nikita P.; Bunkin, Nikolai F.Langmuir (2016), 32 (43), 11245-11255CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Ion-stabilized nanobubbles in bulk aq. solns. of various electrolytes were studied. To understand the ion-specific mechanism of nanobubble stabilization, an approach based on the Poisson--Boltzmann equation at the nanobubble interface and in the near-surface layer was developed. The stabilization of nanobubbles is realized by the adsorption of chaotropic anions at the interface, whereas the influence of cosmotropic cations is weak. With increasing temp., it should be accounted for by blurring the interface due to thermal fluctuations. As a result, the adsorbed state of ions becomes unstable: the nanobubble loses its stability and vanishes. This prediction was proven in the authors' expts. In the case of liq. samples being kept in hermetically sealed ampuls, where the phase equil. at the liq.-gas interface is fulfilled for any temp., the vol. no. d. of nanobubbles decreases with increasing temp. and this decrease is irreversible.
- 29Bunkin, N. F.; Ninham, B. W.; Ignatiev, P. S.; Kozlov, V. A.; Shkirin, A. V.; Starosvetskij, A. V. Long-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensions. J. Biophotonics 2011, 4, 150– 164, DOI: 10.1002/jbio.201000093Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3M7mt1ynug%253D%253D&md5=2de243fb40db7eaf4f3be4663c60593cLong-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensionsBunkin Nikolai F; Ninham Barry W; Ignatiev Pavel S; Kozlov Valery A; Shkirin Alexey V; Starosvetskij Artem VJournal of biophotonics (2011), 4 (3), 150-64 ISSN:.Results of experiments combining laser modulation interference microscopy and Mueller matrix scatterometry show that macroscopic scatterers of light are present in liquids free of external solid impurities. Experimental data on distilled water and aqueous NaCl solutions of various concentrations as well as physiological saline solution are reported. The experimental data can be interpreted by using a model of micron-scale clusters composed of polydisperse air nanobubbles having effective radii of 70-100 nm. Their concentration increases with the growth of ionic content. We hypothesize that under certain conditions those clusters of nanobubbles can affect the erythrocyte structure.
- 30Bunkin, N. F.; Shkirin, A. V.; Kozlov, V. A.; Starosvetskiy, A. V. Laser scattering in water and aqueous solutions of salts. Laser Applications in Life Sciences , 2010; Vol. 7376, p 73761D.Google ScholarThere is no corresponding record for this reference.
- 31Marâechal, Y. The Hydrogen Bond and the Water Molecule, The Physics and Chemistry of Water, Aqueous and Bio Media; Elsevier: Amsterdam, The Netherlands, 2007.Google ScholarThere is no corresponding record for this reference.
- 32Bunkin, N. F.; Shkirin, A. V.; Lyakhov, G. A.; Kobelev, A. V.; Penkov, N. V.; Ugraitskaya, S. V.; Fesenko, E. E., Jr. Droplet-like heterogeneity of aqueous tetrahydrofuran solutions at the submicrometer scale. J. Chem. Phys. 2016, 145, 184501, DOI: 10.1063/1.4966187Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhvVehtLfF&md5=b1bf0da6bf31abbc2e9ce83f687320f8Droplet-like heterogeneity of aqueous tetrahydrofuran solutions at the submicrometer scaleBunkin, N. F.; Shkirin, A. V.; Lyakhov, G. A.; Kobelev, A. V.; Penkov, N. V.; Ugraitskaya, S. V.; Fesenko, E. E.Journal of Chemical Physics (2016), 145 (18), 184501/1-184501/11CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)A droplet formation in aq. solns. of THF (THF) was exptl. detected at the submicrometer scale using two independent laser diagnostic techniques (dynamic light scattering and laser phase microscopy) and described in terms of THF-water intermol. hydrogen bonding. The nanodroplets have a mean size of 300 nm, their refractive index is higher than that of the ambient liq., and they are highly enriched with THF mols. The max. of light scattering intensity falls within the THF concn. range 2-8 mol. %, which corresponds to the vol. no. d. of the nanodroplets ∼1010-1011 cm-3. A theor. explanation of forming the nanodroplets with a high content of THF, which is based on a model of dichotomous noise being applied to the so-termed "twinkling" hydrogen bonds and involves spinodal decompn. in the unstable region enclosed within the dichotomous binodal, is proposed. The parameters of hydrogen bonds in the mol. system "water-THF" were found, and the phase diagram of the soln. with allowance for crosslinking hydrogen bonds was constructed. (c) 2016 American Institute of Physics.
- 33Bunkin, N. F.; Lyakhov, G. A.; Shkirin, A. V.; Krivokhizha, S. V.; Afonin, A. A.; Kobelev, A. V.; Penkov, N. V.; Fesenko, E. E., Jr. Laser Diagnostics of the Mesoscale Heterogeneity of Aqueous Solutions of Polar Organic Compounds. Phys. Wave Phen. 2018, 26, 21– 35, DOI: 10.3103/s1541308x18010041Google ScholarThere is no corresponding record for this reference.
- 34Françon, M. La granularite laser (spekle) et ses applications en optique; Masson: Paris, New York, 1978.Google ScholarThere is no corresponding record for this reference.
- 35Jadhav, A. J.; Barigou, M. Bulk Nanobubbles or Not Nanobubbles: That is the Question. Langmuir 2020, 36, 1699– 1708, DOI: 10.1021/acs.langmuir.9b03532Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVaqsrc%253D&md5=8f6e0a838c8bd8243e3ea5050095b7d0Bulk Nanobubbles or Not Nanobubbles: That is the QuestionJadhav, Ananda J.; Barigou, MostafaLangmuir (2020), 36 (7), 1699-1708CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Bulk nanobubbles are a novel nanoscale bubble system with unusual properties which challenge our understanding of bubble behavior. Because of their extraordinary longevity, their existence is still not widely accepted as they are often attributed to the presence of supramol. structures or contaminants. Nonetheless, bulk nanobubbles are attracting increasing attention in the literature, but reports generally lack objective evidence that the obsd. nano-entities are indeed nanobubbles. In this paper, we use various phys. and chem. anal. techniques to provide multiple evidence that the nano-entities produced mech. in pure water by a continuous high-shear rotor-stator device or acoustic cavitation and spontaneously by water-ethanol mixing are indeed gas-filled domains. We est. that the results presented here combined provide conclusive proof that bulk nanobubbles do exist and they are stable. This paper should help close the debate about the existence of bulk nanobubbles and, hence, enable the scientific community to rather focus on developing the missing fundamental science in this area.
- 36Malyuchenko, N. V.; Tonevitskii, A. G.; Savvateev, M. N.; Bykov, V. A.; Moisenovich, M. M.; Agapov, I. I.; Kozlovskaya, N. V.; Arkhipova, V. S.; Yegorova, S. G.; Kirpichnikov, M. P. Study of the structural features of proteins by intermittent-contact atomic force microscopy. Biophysics 2003, 48, 772– 778Google ScholarThere is no corresponding record for this reference.
- 37Subramanian, D.; Boughter, C. T.; Klauda, J. B.; Hammouda, B.; Anisimov, M. A. Mesoscale Inhomogeneities in Aqueous Solutions of Small Amphiphilic Molecules. Faraday Discuss. 2013, 167, 217– 238, DOI: 10.1039/c3fd00070bGoogle Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2crltVWqtw%253D%253D&md5=f7ed45a8be4963ababc6eaf6b1ce91beMesoscale inhomogeneities in aqueous solutions of small amphiphilic moleculesSubramanian Deepa; Boughter Christopher T; Klauda Jeffery B; Hammouda Boualem; Anisimov Mikhail AFaraday discussions (2013), 167 (), 217-38 ISSN:1359-6640.Small amphiphilic molecules, also known as hydrotropes, are too small to form micelles in aqueous solutions. However, aqueous solutions of nonionic hydrotropes show the presence of a dynamic, loose, non-covalent clustering in the water-rich region, This clustering can be viewed as "micelle-like structural fluctuations". Although these fluctuations are short ranged (approximately 1 nm) and short lived (10 ps-50 ps), they may lead to thermodynamic anomalies. In addition, many experiments on aqueous solutions of hydrotropes show the occasional presence of mesoscale (approximately 100 nm) inhomogeneities. We have combined results obtained from molecular dynamics simulations, small-angle neutron scattering, and dynamic light-scattering experiments carried out on tertiary butyl alcohol (hydrotrope)-water solutions and on tertiary butyl alcohol-water-cyclohexane (hydrophobe) solutions to elucidate the nature and structure of these inhomogeneities. We have shown that stable mesoscale inhomogeneities occur in aqueous solutions of nonionic hydrotropes only when the solution contains a third, more hydrophobic, component. Moreover, these inhomogeneities exist in ternary systems only in the concentration range where structural fluctuations and thermodynamic anomalies are observed in the binary water-hydrotrope solutions. Addition of a hydrophobe seems to stabilize the water-hydrotrope structural fluctuations, and leads to the formation of larger (mesoscopic) droplets. The structure of these mesoscopic droplets is such that they have a hydrophobe-rich core, surrounded by a hydrogen-bonded shell of water and hydrotrope molecules. These droplets can be extremely long-lived, being stable for over a year. We refer to the phenomenon of formation of mesoscopic droplets in aqueous solutions of nonionic hydrotropes containing hydrophobes, as mesoscale solubilization. This phenomenon may represent a ubiquitous feature of nonionic hydrotropes that exhibit clustering in water, and may have important practical applications in areas, such as drug delivery, where the replacement of traditional surfactants may be necessary.
- 38Hand, D. B. The refractivity of protein solutions. J. Biol. Chem. 1935, 108, 703– 707Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaA2MXisFOqsw%253D%253D&md5=3005a512f19a98d173e94bb1e3013f0fRefractivity of protein solutionsHand, David B.Journal of Biological Chemistry (1935), 108 (), 703-7CODEN: JBCHA3; ISSN:0021-9258.By extrapolation of nps - ns. = a C to solns. contg. only protein values for np, the refractivity of the pure protein in the dissolved state, are calcd. These values are proposed as an empirical convenience for describing the rate with which the refraction of protein solns. changes with concn. when the refractivity of the solvent is taken into consideration, thus permitting comparison of one protein with another. The sp. refractive increment, a, is not characteristic of the protein, but varies with the refractivity of the solvent. Values for np are given for serum globulin, urease, serum albumin, horse hemoglobin, ovalbumin, edestin, gliadin, globin, salmine, ovomucoid, casein, paranuclein and ovovitellin.
- 39Kimura, H. Light-scattering properties of fractal aggregates: numerical calculations by a superposition technique and the discrete-dipole approximation. J. Quant. Spectrosc. Radiat. Transfer 2001, 70, 581– 594, DOI: 10.1016/s0022-4073(01)00031-0Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXltFOjur4%253D&md5=82de557514d87483e129a1f6316ff5d5Light-scattering properties of fractal aggregates: numerical calculations by a superposition technique and the discrete-dipole approximationKimura, H.Journal of Quantitative Spectroscopy & Radiative Transfer (2001), 70 (4-6), 581-594CODEN: JQSRAE; ISSN:0022-4073. (Elsevier Science Ltd.)Dust particles in space often grow by mutual collisions and appear to be an agglomeration of individual grains, the morphol. of which can be described by the concept of fractals. The authors study light scattering by fractal aggregates of identical spheres (monomers) using the superposition technique incorporated into the T-matrix method where the orientationally averaged scattering matrix is anal. obtained. The authors also apply the discrete-dipole approxn., in which the dipole polarizability of spherical monomers is detd. by the 1st term of the scattering coeffs. in the Mie theory. Two cases of the ballistic aggregation process (particle-cluster and cluster-cluster aggregations) are considered to model fractal aggregates consisting of silicate or C material. The dependences of light-scattering properties on the monomer sizes, aggregate structures and material compns. are intensively studied. The light-scattering properties of the fractal aggregates strongly depend on the size parameters of the monomers. The difference in the scattering function between the particle-cluster and cluster-cluster aggregates can be seen in the case of monomers much smaller than the wavelength of incident radiation. When the size parameter of monomers exceeds unity, the material compn. of the monomers influences the light-scattering properties of the aggregates, but different morphologies result in similar scattering and polarization patterns. Silicate aggregates consisting of submicron-sized monomers, irresp. of the aggregate size and morphol., produce a backscattering enhancement and a neg. polarization obsd. for dust in the solar system.
- 40Mishchenko, M. I.; Travis, L. D.; Lacis, A. A. Scattering, Absorption, and Emission of Light by Small Particles; Cambridge University Press: Cambridge, 2002.Google ScholarThere is no corresponding record for this reference.
- 41Feder, J. Fractals; Springer: New York, 1988.Google ScholarThere is no corresponding record for this reference.
- 42Tazaki, R.; Tanaka, H.; Okuzumi, S.; Kataoka, A.; Nomura, H. Light scattering by fractal dust aggregates. I. Angular dependence of scattering. Astrophys. J. 2016, 823, 70, DOI: 10.3847/0004-637x/823/2/70Google ScholarThere is no corresponding record for this reference.
- 43Cumper, C. W. N. The stabilization of foams by proteins. Trans. Faraday Soc. 1953, 49, 1360– 1369, DOI: 10.1039/tf9534901360Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaG2cXksVygtg%253D%253D&md5=f67618374847c94dcb0b9f30251cea1cStabilization of foams by proteinsCumper, C. W. N.Transactions of the Faraday Society (1953), 49 (), 1360-9CODEN: TFSOA4; ISSN:0014-7672.Three cryst. proteins (bovine β-globulin, pepsin, and insulin) stabilize the dispersion of air in water, as shown by passing air continuously through a protein soln. The av. life of individual bubbles formed under the surface of protein solns. and under spread protein monolayers was detd. The effects of changing the protein concn., pH, and ionic strength of the solns. were studied and the results correlated with previous observations on the mech. properties of films of the same proteins. Considerable variations were found in the life-times of individual bubbles. The mean of about 10 results was always taken, and the time from successive expts. fell within 10% on either side of their av. The behavior is consistent with protein adsorption occurring in 3 stages: adsorption, surface denaturation, and coagulation. Only surface-denatured protein is effective in stabilizing the air bubbles.
- 44Saint-Jalmes, A.; Peugeot, M.-L.; Ferraz, H.; Langevin, D. Differences between protein and surfactant foams: Microscopic properties, stability and coarsening. Colloids Surf., A 2005, 263, 219– 225, DOI: 10.1016/j.colsurfa.2005.02.002Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXltlaisbw%253D&md5=b6071e8850051cde547ffbb485049856Differences between protein and surfactant foams: Microscopic properties, stability and coarseningSaint-Jalmes, A.; Peugeot, M.-L.; Ferraz, H.; Langevin, D.Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2005), 263 (1-3), 219-225CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Results are presented on foamability, stability and coarsening of foams made either of surfactant (SDS) or of milk protein (casein) solns. Studies were performed at the scales of the gas-liq. interface, thin liq. film and bubble size, to find the correlations between these different scales, and to elucidate the microscopic origins of the macroscopic features. For both systems, foamability concn. thresholds were measured, and a bubble size dependence was found. A clear correlation between the stability of an isolated thin film and the foam stability is always evidenced. However, the mechanism of stability of the casein thin films is different from the surfactant one, and related to the confinement and percolation of casein aggregates. The authors also report results on coarsening at const. liq. fraction, showing that the protein foams coarsen more slowly than the surfactant ones, and that it is due to differences in thin film thickness.
- 45Bunkin, N. F.; Shkirin, A. V.; Penkov, N. V.; Chirikov, S. N.; Ignatiev, P. S.; Kozlov, V. A. The Physical Nature of Mesoscopic Inhomogeneities in Highly Diluted Aqueous Suspensions of Protein Particles. Phys. Wave Phenom. 2019, 27, 102– 112, DOI: 10.3103/s1541308x19020043Google ScholarThere is no corresponding record for this reference.
- 46Roitt, I. Essential Immunology; Blackwell Scientific Publications: Oxford, 1994.Google ScholarThere is no corresponding record for this reference.
- 47Zetasizer Nano Series. User Manual. MAN0317 Issue 3.1 July 2007, Chapter 6. Sample Preparation; Malvern Instruments Ltd.: United Kingdom, 2007.Google ScholarThere is no corresponding record for this reference.
Cited By
Click to copy section linkSection link copied!
Citation Statements
beta
Smart citations by scite.ai include citation statements extracted from the full text of the citing article. The number of the statements may be higher than the number of citations provided by ACS Publications if one paper cites another multiple times or lower if scite has not yet processed some of the citing articles.
Explore this article's citation statements on scite.ai
This article is cited by 54 publications.
- Barry W. Ninham, Nikolai Bunkin, Matthew Battye. The endothelial surface layer-glycocalyx - Universal nano-infrastructure is fundamental to physiology, cell traffic and a complementary neural network. Advances in Colloid and Interface Science 2025, 338 , 103401. https://doi.org/10.1016/j.cis.2025.103401
- А. И. Князькова, М. С. Снегерев, А. П. Вотинцев, В. В. Николаев, Д. А. Вражнов, Ю. В. Кистенев. Количественная оценка толщины гидратной оболочки молекул моногидрата лактозы в водных растворах. Журнал физической химии 2024, 98
(6)
, 87-94. https://doi.org/10.31857/S0044453724060133
- Vadim V. Novikov, Elena V. Yablokova, German O. Stepanov, Natalia N. Rodionova, Sergey A. Tarasov, Ekaterina V. Buravleva, Olga I. Yablonskaya, Vladimir L. Voeikov. Non-Contact Interaction Between Phorbol Myristate Acetate and Aqueous Alcohol Solutions Under Combined Magnetic Fields. Molecules 2024, 29
(23)
, 5814. https://doi.org/10.3390/molecules29235814
- Anastasia Petrova, Sergey Tarasov, Evgeniy Gorbunov, German Stepanov, Olga Fartushnaya, Evgenii Zubkov, Irina Molodtsova, Vladimir Boriskin, Anastasia Zatykina, Alexey Smirnov, Svetlana Zakharova, Sabina Yaroshenko, Anna Ponomareva, Nataliya Petrova, Elena Kardash, Ksenia Ganina, Natalia Rodionova, Alexander Kovalchuk, Oleg Epstein. Phenomenon of Post-Vibration Interactions. Symmetry 2024, 16
(8)
, 958. https://doi.org/10.3390/sym16080958
- A. I. Knyazkova, M. S. Snegerev, A. P. Votintsev, V. V. Nikolaev, D. A. Vrazhnov, Yu. V. Kistenev. Quantitative Assessment of the Hydrate Shell Thickness of Lactose Monohydrate Molecules in Aqueous Solutions. Russian Journal of Physical Chemistry A 2024, 98
(6)
, 1140-1146. https://doi.org/10.1134/S0036024424700067
- Sergei D. Odintsov, Vasilis K. Oikonomou. Towards Modelling Mechanical Shaking Using Potential Energy Surfaces: A Toy Model Analysis. Symmetry 2024, 16
(5)
, 572. https://doi.org/10.3390/sym16050572
- Evgeny E. Fesenko, Elena V. Yablokova, Vadim V. Novikov. Weak Magnetic Fields Regulate the Ability of High Dilutions of Water to Enhance ROS Production by Neutrophils. Applied Sciences 2024, 14
(8)
, 3290. https://doi.org/10.3390/app14083290
- G. O. Stepanov, V. S. Boriskin, N. N. Rodionova, M. M. Fedorova, A. O. Petrova, V. V. Novikov, E. V. Yablokova, D. Yu. Chernikov, A. V. Minakov, S. A. Tarasov. The Effect of Aqueous Solutions Processed Using Gradual Technology on the Emission of a Carbohydrate (Lactose) in the RF Range. Physics of Wave Phenomena 2024, 32
(1)
, 43-47. https://doi.org/10.3103/S1541308X24010084
- G. O. Stepanov, N. N. Rodionova, R. R. Konstantinov, K. A. Subbotin. Effect of adding technologically processed antibodies to interferon-gamma into a parent solution on the structural features of triglycine sulfate crystals grown from this solution. Fine Chemical Technologies 2024, 18
(6)
, 517-533. https://doi.org/10.32362/2410-6593-2023-18-6-517-533
- Kirill A. Subbotin, Yana S. Didenko, Anatolii I. Titov, Denis A. Lis, Sergei K. Pavlov, Pavel A. Volkov, Kristina I. Runina, Valerii V. Voronov, Elena V. Chernova, Olga N. Lis, Kristina V. Kuleshova, Yulia I. Zimina. Influence of Ultrahigh Dilution Treatment of the Charge on the Growth and Spectroscopic Properties of Nd:MgMoO4 Potential Laser Crystal. Crystals 2024, 14
(1)
, 100. https://doi.org/10.3390/cryst14010100
- Egor I. Nagaev, Elena A. Molkova, Vladimir I. Pustovoy, Tatyana A. Matveeva, Dmitry A. Zakharov, Alexander V. Simakin, Evgenia V. Stepanova, Natalia A. Semenova, Veronika E. Reut, Valery P. Kalinitchenko, Valery A. Kozlov, Nikolai F. Bunkin. Possible Approaches to Studying the Influence of Magnetic Fields and Mechanical Effects on the Physicochemical Properties of Aqueous IgG Colloids. Applied Sciences 2023, 13
(24)
, 13055. https://doi.org/10.3390/app132413055
- E. S. Don, G. O. Stepanov, S. A. Tarasov. The effects of physical treatment on physicochemical and biological properties of water and aqueous solutions. Fine Chemical Technologies 2023, 18
(5)
, 426-445. https://doi.org/10.32362/2410-6593-2023-18-5-426-445
- N. V. Petrova, S. A. Tarasov, A. A. Galkina, A. S. Poroshina, M. S. Sundukova, V. V. Smirnov. Antiallergic Effects of Technologically Processed Antibodies to MHC II. Bulletin of Experimental Biology and Medicine 2023, 175
(6)
, 801-803. https://doi.org/10.1007/s10517-023-05950-8
- Oleg Epstein. The Supramolecular Matrix Concept. Symmetry 2023, 15
(10)
, 1914. https://doi.org/10.3390/sym15101914
- Leonid L. Chaikov, Marina N. Kirichenko, Svetlana V. Krivokhizha, Maskhud R. Kupov, Andrey N. Lobanov, Pavel P. Sverbil, Egor I. Nagaev, Alexey V. Shkirin. Two Convenient Methods for Detection of Non-Dairy Fats in Butter by Dynamic Light Scattering and Luminescence Spectroscopy. Applied Sciences 2023, 13
(15)
, 8563. https://doi.org/10.3390/app13158563
- D. A Serov, E. I Nagaev, A. I Kuleshova, V. E Reut, M. E Astashev. Influence of laser radiation of a surgical laser on the structure of bovine serum albumin molecules in vitro. Биофизика 2023, 68
(3)
, 474-481. https://doi.org/10.31857/S0006302923030079
- Kristina N. Woods. Modeling of protein hydration dynamics is supported by THz spectroscopy of highly diluted solutions. Frontiers in Chemistry 2023, 11 https://doi.org/10.3389/fchem.2023.1131935
- D. A. Serov, E. I. Nagaev, A. I. Kuleshova, V. E. Reut, M. E. Astashev. The Effect of Surgical Laser Radiation on the Structure of Bovine Serum Albumin in vitro. Biophysics 2023, 68
(3)
, 376-382. https://doi.org/10.1134/S0006350923030181
- M. E. Astashev, D. A. Serov, R. M. Sarimov, S. V. Gudkov. Influence of the Vibration Impact Mode on the Spontaneous Chemiluminescence of Aqueous Protein Solutions. Physics of Wave Phenomena 2023, 31
(3)
, 189-199. https://doi.org/10.3103/S1541308X23030020
- G. Yu Lomakina, N. N Ugarova. Alteration of enzyme-substrate interactions by ultra-high dilutions of the substrate. Биофизика 2023, 68
(2)
, 230-240. https://doi.org/10.31857/S0006302923020035
- E. V. Kardash, I. A. Ertuzun, I. V. Alekseeva, S. A. Tarasov. Efficacy of the Technologically Processed Antibodies to the Brain-Specific S100 Protein in a Rat Model of Hemorrhagic Stroke. Bulletin of Experimental Biology and Medicine 2023, 174
(6)
, 741-744. https://doi.org/10.1007/s10517-023-05783-5
- Amanda Västberg, Hans Bolinsson, Mats Leeman, Lars Nilsson, Tommy Nylander, Kushal Sejwal, Ida-Maria Sintorn, Kristina Lidayová, Helen Sjögren, Marie Wahlgren, Ulla Elofsson. Investigating thermally induced aggregation of Somatropin- new insights using orthogonal techniques. International Journal of Pharmaceutics 2023, 637 , 122829. https://doi.org/10.1016/j.ijpharm.2023.122829
- G. Yu. Lomakina, N. N. Ugarova. Alteration of Enzyme-substrate Interactions by Ultra-high Dilutions of the Substrate. Biophysics 2023, 68
(2)
, 167-175. https://doi.org/10.1134/S0006350923020148
- Atikah Wan Nafi, Mojtaba Taseidifar, Richard M. Pashley, Barry W. Ninham. Size control of precipitated particles of amino acids using a bubble column evaporator. Heliyon 2023, 9
(2)
, e13516. https://doi.org/10.1016/j.heliyon.2023.e13516
- Atikah Wan Nafi, Mojtaba Taseidifar, Richard M. Pashley, Barry W. Ninham. The effect of amino acids on bubble coalescence in aqueous solution. Journal of Molecular Liquids 2023, 369 , 120963. https://doi.org/10.1016/j.molliq.2022.120963
- Egor I. Nagaev, Ilya V. Baimler, Alexey S. Baryshev, Veronika E. Reut, Maxim E. Astashev, , . Interaction of Nd:YAG Laser Radiation with Bovine Serum Albumin Solution. BIO Web of Conferences 2023, 57 , 02006. https://doi.org/10.1051/bioconf/20235702006
- Carlos Acuña, Alfonso Mier y Terán, Maria Olga Kokornaczyk, Stephan Baumgartner, Mario Castelán. Deep learning applied to analyze patterns from evaporated droplets of Viscum album extracts. Scientific Reports 2022, 12
(1)
https://doi.org/10.1038/s41598-022-19217-1
- N. V. Petrova, A. G. Emelyanova, A. L. Kovalchuk, S. A. Tarasov. The Role of MHC Class I and Class II Molecules in Antibacterial Immunity and Treatment of Bacterial Diseases. Antibiotics and Chemotherapy 2022, 67
(7-8)
, 71-81. https://doi.org/10.37489/0235-2990-2022-67-7-8-71-81
- O. Maslennikova, A. Sibirev, M. Shipko, M. Stepovich. FEATURES OF PROTEIN-INDUCED ASSOCIATES AT SUPERHIGH DILUTION OF ANTIBODIES TO INTERFERON-γ. Russian Journal of Biological Physics and Chemisrty 2022, 7
(3)
, 467-475. https://doi.org/10.29039/rusjbpc.2022.0546
- Yu. O. Shulpekova, I. V. Maev, V. B. Grinevich, I. B. Khlynov, Yu. G. Shvarts, V. T. Ivashkin. Technologically-Treated Polyclonal Affinity-Purified Antibodies to the Tumor Necrosis Factor-α, Brain Specific S-100 Protein and Histamine in Treatment of Functional Dyspepsia: Results of the Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial. Russian Journal of Gastroenterology, Hepatology, Coloproctology 2022, 32
(3)
, 40-51. https://doi.org/10.22416/1382-4376-2022-32-3-40-51
- Alexandra G. Emelianova, Natalia V. Petrova, Christophe Fremez, Maxime Fontanié, Sergey А. Tarasov, Оleg I. Epstein. Therapeutic potential of highly diluted antibodies in antibiotic-resistant infection. European Journal of Pharmaceutical Sciences 2022, 173 , 106161. https://doi.org/10.1016/j.ejps.2022.106161
- A. V. Shkirin, D. N. Ignatenko, S. N. Chirikov, A. V. Vorobev, S. V. Gudkov. Application of Laser Polarimetric Scatterometry in the Study of Water-Based Multicomponent Bioorganic Systems on the Example of Cow Milk. Physics of Wave Phenomena 2022, 30
(3)
, 186-195. https://doi.org/10.3103/S1541308X22030116
- Dmitry N. Ignatenko, Alexey V. Shkirin, Yakov P. Lobachevsky, Sergey V. Gudkov. Applications of Mueller Matrix Polarimetry to Biological and Agricultural Diagnostics: A Review. Applied Sciences 2022, 12
(10)
, 5258. https://doi.org/10.3390/app12105258
- Anastasia V. Shishkina, Alexander A. Ksenofontov, Nikita V. Penkov, Mikhail V. Vener. Diclofenac Ion Hydration: Experimental and Theoretical Search for Anion Pairs. Molecules 2022, 27
(10)
, 3350. https://doi.org/10.3390/molecules27103350
- Nataliya V. Petrova, Sergey A. Tarasov, Oleg I. Epstein, Caroline Dubroca, Thierry Sulpice. Highly Diluted Antibodies to eNOS Restore Endothelium Function in Aortic Rings From Hypertensive Rats. Dose-Response 2022, 20
(2)
https://doi.org/10.1177/15593258221099281
- Barry W. Ninham, Polina N. Bolotskova, Sergey V. Gudkov, Ekaterina N. Baranova, Valeriy A. Kozlov, Alexey V. Shkirin, Minh Tuan Vu, Nikolai F. Bunkin. Nafion Swelling in Salt Solutions in a Finite Sized Cell: Curious Phenomena Dependent on Sample Preparation Protocol. Polymers 2022, 14
(8)
, 1511. https://doi.org/10.3390/polym14081511
- N.F. Bunkin, S.V. Bashkin, S.V. Gudkov, M.S. Kiryanova, V.A. Kozlov. Non-Stationarity Effects in Polymer Membrane Swelling as Studied by Infrared Fourier Spectrometry Technique. Herald of the Bauman Moscow State Technical University. Series Natural Sciences 2022,
(1 (100))
, 122-140. https://doi.org/10.18698/1812-3368-2022-1-122-140
- Barry Ninham, Brandon Reines, Matthew Battye, Paul Thomas. Pulmonary surfactant and COVID-19: A new synthesis. QRB Discovery 2022, 3 https://doi.org/10.1017/qrd.2022.1
- Anna Baranova, Anastasiya Lykina, Daria Antonova, Olga Smolyanskaya. Optical Properties of Crystalline Lactose Fluidized with Dilutions of Various Substances in the Terahertz Frequency Range. Pharmaceutics 2022, 14
(1)
, 32. https://doi.org/10.3390/pharmaceutics14010032
- Kristina N. Woods. RETRACTED ARTICLE: New insights into the microscopic interactions associated with the physical mechanism of action of highly diluted biologics. Scientific Reports 2021, 11
(1)
https://doi.org/10.1038/s41598-021-93326-1
- , O. I. Dotsenko, G. V. Taradina, , А. М. Mischenko, . Peroxidase activity of erythrocytes hemoglobin under action of low-frequency vibration. Studia Biologica 2021, 15
(4)
, 3-16. https://doi.org/10.30970/sbi.1504.666
- O. I. Dotsenko, А. М. Mischenko, G. V. Taradina. Vibration influence on the O2-dependent processes activity in human erythrocytes. Regulatory Mechanisms in Biosystems 2021, 12
(3)
, 452-458. https://doi.org/10.15421/022162
- Alexey V. Shkirin, Dmitry N. Ignatenko, Sergey N. Chirikov, Nikolai F. Bunkin, Maxim E. Astashev, Sergey V. Gudkov. Analysis of Fat and Protein Content in Milk Using Laser Polarimetric Scatterometry. Agriculture 2021, 11
(11)
, 1028. https://doi.org/10.3390/agriculture11111028
- Nikita Penkov. Antibodies Processed Using High Dilution Technology Distantly Change Structural Properties of IFNγ Aqueous Solution. Pharmaceutics 2021, 13
(11)
, 1864. https://doi.org/10.3390/pharmaceutics13111864
- Limin Zhou, Shuo Wang, Lijuan Zhang, Jun Hu. Generation and stability of bulk nanobubbles: A review and perspective. Current Opinion in Colloid & Interface Science 2021, 53 , 101439. https://doi.org/10.1016/j.cocis.2021.101439
- M. N. Kirichenko, A. V. Shkirin, L. L. Chaikov, A. V. Simakin, N. V. Tcherniega, S. V. Gudkov. Structure and refractive index of fibrin protofibril aggregates according to laser phase microscopy accompanied by DLS and AFM. Biomedical Optics Express 2021, 12
(5)
, 2938. https://doi.org/10.1364/BOE.420261
- N. F. Bunkin, V. A. Kozlov, M. S. Kir’yanova, R. S. Safronenkov, P. N. Bolotskova, V. S. Gorelik, Y. Joraev, L. M. Sabirov, A. E. Primenko, M. T. Vu. Fourier IR Spectroscopy Study of the Effects of Unsteadiness on the Process of Swelling of Polymeric Membranes. Optics and Spectroscopy 2021, 129
(4)
, 460-470. https://doi.org/10.1134/S0030400X2104007X
- P. N. Bolotskova, N. F. Bunkin, V. A. Kozlov, T. Yu. Komkova, M. S. Kir’yanova, R. S. Safronenkov, M. T. Vu. The Role of Shaking of a Liquid Sample in the Dynamics of Polymer Membrane Swelling: A Cell of Limited Volume. Physics of Wave Phenomena 2021, 29
(2)
, 114-122. https://doi.org/10.3103/S1541308X21020047
- I. A. Shcherbakov. Influence of External Impacts on the Properties of Aqueous Solutions. Physics of Wave Phenomena 2021, 29
(2)
, 89-93. https://doi.org/10.3103/S1541308X21020114
- O. V. Slatinskaya, Yu. N. Pyrkov, S. A. Filatova, D. A. Guryev, N. V. Penkov. Study of the Effect of Europium Acetate on the Intermolecular Properties of Water. Frontiers in Physics 2021, 9 https://doi.org/10.3389/fphy.2021.641110
- Nikita Penkov, Nadezda Penkova. Analysis of Emission Infrared Spectra of Protein Solutions in Low Concentrations. Frontiers in Physics 2020, 8 https://doi.org/10.3389/fphy.2020.624779
- Barry W. Ninham, Polina N. Bolotskova, Sergey V. Gudkov, Yulchi Juraev, Mariya S. Kiryanova, Valeriy A. Kozlov, Roman S. Safronenkov, Alexey V. Shkirin, Elena V. Uspenskaya, Nikolai F. Bunkin. Formation of Water-Free Cavity in the Process of Nafion Swelling in a Cell of Limited Volume; Effect of Polymer Fibers Unwinding. Polymers 2020, 12
(12)
, 2888. https://doi.org/10.3390/polym12122888
- Nikita Penkov, Eugeny Fesenko. Development of Terahertz Time-Domain Spectroscopy for Properties Analysis of Highly Diluted Antibodies. Applied Sciences 2020, 10
(21)
, 7736. https://doi.org/10.3390/app10217736
- Sergey V. Gudkov, Nikita V. Penkov, Ilya V. Baimler, Gennady A. Lyakhov, Vladimir I. Pustovoy, Alexander V. Simakin, Ruslan M. Sarimov, Ivan A. Scherbakov. Effect of Mechanical Shaking on the Physicochemical Properties of Aqueous Solutions. International Journal of Molecular Sciences 2020, 21
(21)
, 8033. https://doi.org/10.3390/ijms21218033
Learn about these metrics
Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.
Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.
Recommended Articles
Abstract
Figure 1
Figure 1. DLS intensity distribution over the particle sizes in water: before shaking (blue solid curve) and immediately after shaking (red dashed curve). Total scattering intensities are Itot(173°) = 12 kcps (0.5 nm—62.2%, 250 nm—37.8%) and Itot(173°) = 40 kcps, correspondingly.
Figure 2
Figure 2. LPM images of a bubston with d ≈ 250 nm in water after shaking: (a) 2D distribution of the optical path difference (OPD) and (b) 1D profile, Δh = −20 nm.
Figure 3
Figure 3. DLS intensity distribution over the particle sizes in an EWM: before shaking (blue solid curve) and immediately after shaking (red dashed curve). Total scattering intensities are Itot(173°) = 80 kcps and Itot(173°) = 85 kcps, correspondingly.
Figure 4
Figure 4. LPM images of a mesoscale particle with a size of d ≈ 150 nm, presumably, an ethanol-enriched mesodroplet in an unshaken EWM: (a) 2D distribution of the OPD and (b) 1D profile of this particle, Δh ≈ 7 nm.
Figure 5
Figure 5. DLS intensity distribution over the particle sizes in aqueous IgG solution with volume number density 3 × 1014 cm–3 before shaking. Average total intensity (minus background scattering) Itot(173°) = 255 kcps (12 nm peak is 18.2% and 300 nm peak is 81.8%).
Figure 6
Figure 6. LPM images of inhomogeneities in aqueous IgG solution before shaking: (a) 2D distribution of the OPD for particles with a size of about 300 nm and (b) 1D profile of this distribution, Δh ≈ 25 nm.
Figure 7
Figure 7. Dependences of the scattering matrix elements F11(θ), f12(θ), f34(θ), and f44(θ) measured via LPS in aqueous IgG solution before shaking. The circles are experimental points, the solid line is the theoretical approximation by multitype spherical particles, and the dashed line is the Rayleigh–Gans–Debye approximation for the IgG aggregates. F11(exp) (θ) is plotted so that F11(exp) (30°) = F11(theor) (30°); for more detail, see ref (40).
Figure 8
Figure 8. DLS intensity distribution over the particle sizes in aqueous IgG solution with volume number density 3 × 1014 cm–3 immediately after shaking. Average total intensity (background scattering is subtracted) Itot(173°) = 844 kcps (12 nm peak is 4.8%, 250 nm peak is 45.1%, 600 nm peak is 30.5%, and 3000 nm peak is 19.6%).
Figure 9
Figure 9. Characteristic LPM images (2D distributions of the OPD and the corresponding 1D profiles) of particles in a sample taken from the surface of the initial aqueous IgG solution (volume number density 3 × 1014 cm–3) immediately after shaking: (a,b) nanobubble–IgG aggregate dimer and (c,d) agglomerate of nanobubbles and IgG aggregates.
Figure 10
Figure 10. DLS intensity distribution over the particle sizes in 100-fold dilution of shaken aqueous IgG solution (the initial concentration 3 × 1014 cm–3). Average total intensity (minus background scattering) Itot(173°) = 21 kcps (250 nm peak is 62% and 3000 nm peak is 38%).
Figure 11
Figure 11. DLS intensity distribution over the particle sizes: (a) initial IgG solution in an EWM (36.7 vol %) with a volume number density of IgG molecules being 3 × 1014 cm–3, Itot(173°) = 5820 kcps before shaking; (b) same solution after filtration through a membrane with a pore size of 450 nm, Itot(173°) = 50 kcps (12 nm peak is 40%, 150 nm peak is 50%, and 900 nm peak is 10%); and (c) filtered solution immediately after shaking Itot = 389 kcps, 12 nm peak is 5%, 120 nm peak is 5.7%, and 400 nm peak is 89.3%). Here, Itot is the average total intensity (background scattering was subtracted).
Figure 12
Figure 12. DLS intensity distribution over the particle sizes in the initial IgG solution (3 × 1014 cm–3) after filtration through a membrane with a pore size of 220 nm, Itot(173°) = 27 kcps (4.5 nm peak is 22.8%, 18 nm peak is 31.4%, and 170 nm peak is 45.8%).
Figure 13
Figure 13. LPM images of a particle with a size of ≈900 nm in EWM solution of IgG before shaking: (a) 2D distribution of the OPD and (b) 1D profile of the distribution.
Figure 14
Figure 14. Dependences of the scattering matrix elements F11(θ), f12(θ), f34(θ), and f44(θ) measured via LPS in EWM solution of IgG before shaking. The circles are experimental points, the solid line is the theoretical approximation by multitype spherical particles, and the dotted line is the Rayleigh–Gans–Debye approximation for IgG aggregates. As in Figure 7, F11(exp) (θ) is plotted so that F11(exp) (30°) = F11(theor) (30°).
Figure 15
Figure 15. DLS intensity distribution over the particle sizes for 100-fold dilution of shaken IgG solution in an EWM (the initial concentration 3 × 1014 cm–3). Average total intensity (minus background scattering) Itot(173°) = 157 kcps (150 nm peak is 20%, and 750 nm peak is 80%).
Figure 16
Figure 16. Micrographs of gas bubbles in liquid samples, recorded immediately after shaking: (a) aqueous IgG solution with the concentration 3 × 1012 cm–3 and (b) pure water.
Figure 17
Figure 17. Micrographs of gas bubbles in the samples, recorded immediately after shaking: (a) solution of IgG in an EWM with the concentration 3 × 1012 cm–3 and (b) pure ethanol.
Figure 18
Figure 18. DLS intensity distribution over the particle sizes in monodisperse aqueous suspensions of polystyrene latex spheres at a scattering angle of 173°: (a) d = 200 nm and (b) d = 1200 nm.
Figure 19
Figure 19. LPM images (2D distribution of OPD and the corresponding 1D profiles) of spherical polystyrene latex particles in monodisperse aqueous suspensions: (a,b) particle with d = 200 nm and (c,d) particle with d = 1200 nm.
Figure 20
Figure 20. Dependence of the coefficient γ vs particle size.
References
This article references 47 other publications.
- 1Gudkov, S. V.; Lyakhov, G. A.; Pustovoy, V. I.; Shcherbakov, I. A. Influence of Mechanical Effects on the Hydrogen Peroxide Concentration in Aqueous Solutions. Phys. Wave Phenom. 2019, 27, 141– 144, DOI: 10.3103/s1541308x19020092There is no corresponding record for this reference.
- 2Lee, J. K.; Walker, K. L.; Han, H. S.; Kang, J.; Prinz, F. B.; Waymouth, R. M.; Nam, H. G.; Zare, R. N. Spontaneous generation of hydrogen peroxide from aqueous microdroplets. Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 19294– 19298, DOI: 10.1073/pnas.19118831162https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVGgu7nP&md5=6e4ea4b03c9ee031c2344d9da262e1a2Spontaneous generation of hydrogen peroxide from aqueous microdropletsLee, Jae Kyoo; Walker, Katherine L.; Han, Hyun Soo; Kang, Jooyoun; Prinz, Fritz B.; Waymouth, Robert M.; Nam, Hong Gil; Zare, Richard N.Proceedings of the National Academy of Sciences of the United States of America (2019), 116 (39), 19294-19298CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)We show H2O2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1μm to 20μm in diam.). Prodn. of H2O2, as assayed by H2O2-sensitive fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H2O2. The generated H2O2 concn. was ≈30μM (≈1 part per million) as detd. by titrn. with potassium titanium oxalate. Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets, indicating that pure water microdroplets directly generate H2O2 without help from O2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H2O2 formation and report a no. of different expts. exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH- at or near the surface of the water microdroplet. This catalyst-free and voltage-free H2O2 prodn. method provides innovative opportunities for green prodn. of hydrogen peroxide.
- 3Rieth, M.; Kempf, A. M.; Stein, O. T.; Kronenburg, A.; Hasse, C.; Vascellari, M. Evaluation of a flamelet/progress variable approach for pulverized coal combustion in a turbulent mixing layer. Proceedings of the Combustion Institute 2019, 37, 2927– 2934, DOI: 10.1016/j.proci.2018.05.1503https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsVejtb3N&md5=b1892a4f858ba8ed15befb115189762fEvaluation of a flamelet/progress variable approach for pulverized coal combustion in a turbulent mixing layerRieth, Martin; Kempf, Andreas M.; Stein, Oliver T.; Kronenburg, Andreas; Hasse, Christian; Vascellari, MicheleProceedings of the Combustion Institute (2019), 37 (3), 2927-2934CODEN: PCIRC2; ISSN:1540-7489. (Elsevier B.V.)A steady flamelet/progress variable (FPV) approach for pulverized coal flames is employed to simulate coal particle burning in a turbulent shear and mixing layer. The configuration consists of a carrier-gas stream of air laden with coal particles that mixes with an oxidizer stream of hot products from lean combustion. Carrier-phase DNS (CP-DNS) are performed, where the turbulent flow field is fully resolved, whereas the coal is represented by Lagrangian point particles. CP-DNS with direct chem. integration is performed first and provides state-of-the-art validation data for FPV modeling. In a second step the control variables for FPV are extd. from the CP-DNS and used to test if the tabulated manifold can correctly describe the reacting flow (a priori anal.). Finally a fully coupled a posteriori FPV simulation is performed, where only the FPV control variables are transported, and the chem. state is retrieved from the table and fed back to the flow solver. The a priori results show that the FPV approach is suitable for modeling the complex reacting multiphase flow considered here. The a posteriori data is similarly in good agreement with the ref. CP-DNS, although stronger deviations than a priori can be obsd. These discrepancies mainly appear in the upper flame (of the present DNS), where premixing and highly unsteady extinction and re-ignition effects play a role, which are difficult to capture by steady non-premixed FPV modeling. However, the present FPV model accurately captures the lower, more stable flame that burns in non-premixed mode.
- 4Nada, M. H.; Gillan, E. G.; Larsen, S. C. Mechanochemical reaction pathways in solvent-free synthesis of ZSM-5. Microporous Mesoporous Mater. 2019, 276, 23– 28, DOI: 10.1016/j.micromeso.2018.09.0094https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvVeqsrvJ&md5=480aac46fb4d298676751e8fc873916bMechanochemical reaction pathways in solvent-free synthesis of ZSM-5Nada, Majid H.; Gillan, Edward G.; Larsen, Sarah C.Microporous and Mesoporous Materials (2019), 276 (), 23-28CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Solvent-free methods for the synthesis of ZSM-5 have been previously reported in the literature. These methods typically involve grinding the starting materials together prior to the hydrothermal reaction step. However, very little is known about the reaction intermediates formed during the mechanochem. pre-reaction or about how the pre-reaction impacts the subsequent hydrothermal synthesis conditions (temp. and length of hydrothermal treatment). In this study, the solvent-free synthesis of ZSM-5 was investigated while varying the length and type of grinding (manual, ball-mill) and the components of the reaction mixt. The initial reactions that occurred between the solid-state raw materials during grinding were monitored by powder X-ray diffraction (pXRD). Extended grinding initiates exchange reactions between several reagents to form NaCl and to liberate ammonia and water. The resulting wet paste undergoes facile thermal conversion to cryst. zeolite ZSM-5 framework structures. These results provide valuable insights used to guide the optimization of the synthesis conditions required to prep. stable, cryst. and high surface area ZSM-5 under solvent-free synthesis conditions. The solvent-free approach contributes to the overall goal of a greener, more sustainable ZSM-5 synthesis.
- 5Belhouchet, H.; Sahraoui, T.; Belhouchet, K.; Romero, M. Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powder. J. Aust. Ceram. Soc. 2019, 55, 135– 144, DOI: 10.1007/s41779-018-0219-y5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFGrurrL&md5=230ddd6c64fd74d6be33d497dff7f761Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powderBelhouchet, Hocine; Sahraoui, Toufik; Belhouchet, Khaled; Romero, MaximinaJournal of the Australian Ceramic Society (2019), 55 (1), 135-144CODEN: JACSGZ; ISSN:2510-1579. (Springer)In this work, the effect of heating rate and mech. activation on the reaction of kaolin and aluminum powder was investigated. A batch comprised of 89.5 wt% kaolin and 10.5 wt% aluminum powders was mixed and milled in a planetary ball-mill for 1, 5, 10, 20 and 40 h. The mixt. powders were heat treated with a heating rate of 5, 10, 15, 20, 30 and 40 °C/min, resp. After milling for 20 and 40 h, the results showed the formation of free silicon, quartz and nacrite (Al2Si2(OH)4) at room temp. The kaolinite dehydroxylation, aluminum oxidn. and the θ- to α-Al2O3 transformations are highly affected by heating rate and mech. activation. As compared with the smallest heating rate, the mixts. heated with faster heating rate show the disappearance of the peak corresponding to the oxidn. of aluminum and the appearance of a second peak corresponding to the formation of α-Al2O3. The intensity of the last peak increases with increasing of the heating rate and milled at lower milling time. The effects of heating rate in the reaction of kaolin and aluminum powder are attributed to the amorphization of kaolinite, the diffusion of Al3+ to form an amorphous alumina layer on the particle surface and the generation of microcracks at the particle surface of aluminum powder.
- 6European Directorate for the Quality of Medicines & HealthCare. European Pharmacopoeia, 9th Edition, Suppl. 9.3; Council of Europe: Strasbourg, 2017.There is no corresponding record for this reference.
- 7Banga, A. K. Therapeutic Peptides and IgGs: Formulation, Processing, and Delivery Systems; CRC Press: Boca Raton, 2015.There is no corresponding record for this reference.
- 8Wang, W.; Roberts, C. J. Aggregation of therapeutic IgGs; John Wiley & Sons, Inc.: Hoboken, New Jersey, 2010.There is no corresponding record for this reference.
- 9Joubert, M. K.; Luo, Q.; Nashed-Samuel, Y.; Wypych, J.; Narhi, L. O. Classification and Characterization of Therapeutic Antibody Aggregates. J. Biol. Chem. 2011, 286, 25118, DOI: 10.1074/jbc.m110.1604579https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXosFGmt7g%253D&md5=ec705e8e509fabf4ccd1d7a31083ad02Classification and Characterization of Therapeutic Antibody AggregatesJoubert, Marisa K.; Luo, Quan-Zhou; Nashed-Samuel, Yasser; Wypych, Jette; Narhi, Linda O.Journal of Biological Chemistry (2011), 286 (28), 25118-25133CODEN: JBCHA3; ISSN:0021-9258. (American Society for Biochemistry and Molecular Biology)A host of diverse stress techniques was applied to a monoclonal antibody (IgG2) to yield protein particles with varying attributes and morphologies. Aggregated solns. were evaluated for percent aggregation, particle counts, size distribution, morphol., changes in secondary and tertiary structure, surface hydrophobicity, metal content, and reversibility. Chem. modifications were also identified in a sep. report. Aggregates were categorized into seven discrete classes, based on the traits described. Several addnl. mols. (from the IgG1 and IgG2 subtypes as well as i.v. IgG) were stressed and defined with the same classification system. The mechanism of protein aggregation and the type of aggregate formed depends on the nature of the stress applied. Different IgG mols. appear to aggregate by a similar mechanism under the same applied stress. Aggregates created by harsh mech. stress showed the largest no. of subvisible particles, and the class generated by thermal stress displayed the largest no. of visible particles. Most classes showed a disruption of the higher order structure, with the degree of disorder depending on the stress process. Particles in all classes (except thermal stress) were at least partially reversible upon diln. in pH 5 buffer. High copper content was detected in isolated metal-catalyzed aggregates, a stress previously shown to produce immunogenic aggregates. In conclusion, protein aggregates can be a very heterogeneous population, whose qualities are the result of the type of stress that was experienced.
- 10Evdokimov, I. A.; Titov, S. A.; Titov, S. A.; Polyansky, K. K.; Saiko, D. S. Ultrafiltration concentrating of curd whey after electroflotation treatment. Foods Raw Mater. 2017, 5, 131– 136, DOI: 10.21179/2308-4057-2017-1-131-13610https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXls1Sksbo%253D&md5=b5405d24e531290f349eeb6b14949155Ultrafiltration concentrating of curd whey after electroflotation treatmentEvdokimov, I. A.; Titov, S. A.; Polyansky, K. K.; Saiko, D. S.Foods and Raw Materials (2017), 5 (1), 131-136CODEN: FRMOA6; ISSN:2310-9599. (Kemerovo Technological Institute of Food Industry)This work offers a view on the outcomes of a study focusing on ultrafiltration of curd whey treated on the basis of the membrane electroflotation method in order to ensure more complete extn. of whey proteins when processing recoverable dairy crude. The feature that makes the method different is the presence of membranes between the anode and the cathode while the machines for membrane electroflotation are designed so that current does not run through the whey. To det. the element compn. of whey prior to and after electroflotation the method of electron probe X-ray microanal. was used. It has been shown that the filtration rate of whey treated through electroflotation nearly doubles up if compared to the initial rate. There has also been detected the dependence related to the impact that the concn. of solids and the pressure have on the filtration rate; besides, the kinetics of the ultrafiltration process has been investigated. The method of electron probe X-ray microanal. was employed to study the element compn. of whey both before and after the electroflotation treatment. The increase in the whey ultrafiltration rate after electroflotation can be explained by a growing Hydrogen index and a reduced concn. of Calcium after electroflotation. Besides, a quant. phys. model of whey ultrafiltration was developed, which takes into view specific features of polarization layer formation. The model implies conditional division of whey flow at the membrane surface into two streams - a normal one and a tangential one. Part of the protein mols. transported by the normal flow settles on the membrane surface while the other part of them remains near the surface up until it is pushed into the whey bulk by protein mols. of the tangential flow. That all mentioned above fixes certain elements of newness in the field of membrane technologies. The study was performed at the Voronezh State University of Engineering Technologies and the North Caucasus Federal University (Russian Federation).
- 11Yoon, R.-H. The role of hydrodynamic and surface forces in bubble–particle interaction. Int. J. Min. Process 2000, 58, 128– 143, DOI: 10.1016/s0301-7516(99)00071-xThere is no corresponding record for this reference.
- 12Ralston, J.; Fornasiero, D.; Hayes, R. Bubble–particle attachment and detachmentin flotation. Int. J. Min. Process 1999, 56, 133– 164, DOI: 10.1016/s0301-7516(98)00046-512https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXjsFKlsrc%253D&md5=d263d53f2b566cb854a1282b05998b82Bubble-particle attachment and detachment in flotationRalston, John; Fornasiero, Daniel; Hayes, RobertInternational Journal of Mineral Processing (1999), 56 (1-4), 133-164CODEN: IJMPBL; ISSN:0301-7516. (Elsevier Science B.V.)The mechanism by which particles and bubbles interact captures many of the central concepts of colloid science and hydrodynamics and is an example of heterocoagulation. Hydrodynamics, interfacial (including capillary) forces, particle and bubble behavior and soln. chem. are all interwoven. The processes of attachment and detachment are focused upon here. The identification is considered of a flotation 'domain', the deformation of a bubble surface upon interaction with a solid surface, the kinetics of three phase contact line expansion and the detn. of attachment efficiencies through to the direct measurement of bubble-particle interaction forces. The results, concepts, and implications of this work are discussed.
- 13Rubio, J.; Capponi, F.; Matiolo, E.; Nunes, D.; Guerrero, C. P.; Berkowitz, G. Advances in flotation of mineral fines. Proceedings XXII International Mineral Processing Congress (IMPC) , 2003; pp 1014– 1022.There is no corresponding record for this reference.
- 14Fuerstenau, M. C.; Yoon, R. H.; Jameson, G. J. Froth Flotation: A Century of Innovation; Society for Mining, Metallurgy, and Exploration, 2007.There is no corresponding record for this reference.
- 15Sobhy, A.; Tao, D. Nanobubble column flotation of fine coal particles and associated fundamentals. Int. J. Min. Process. 2013, 124, 109– 116, DOI: 10.1016/j.minpro.2013.04.01615https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXotlOrsr4%253D&md5=a13eff3717072926caf3499e97f5eff0Nanobubble column flotation of fine coal particles and associated fundamentalsSobhy, A.; Tao, D.International Journal of Mineral Processing (2013), 124 (), 109-116CODEN: IJMPBL; ISSN:0301-7516. (Elsevier B.V.)Froth flotation is a widely used, cost effective particle sepn. process. However, its high performance is limited to a narrow particle size range between approx. 50 to 600 μm for coal and 10 to 100 μm for minerals. Outside this range, the efficiency of froth flotation decreases significantly, esp. for difficult-to-float particles of weak hydrophobicity (e.g., oxidized coal).This study was aimed at enhancing recovery of an Illinois fine coal sample using a specially designed flotation column featuring a hydrodynamic cavitation nanobubble generator. Nanobubbles that are mostly smaller than 1 μm can be formed selectively on hydrophobic coal particles from dissolved air in coal slurry. Results indicate that the combustible recovery of a - 150 μm coal increased by 5-50% in the presence of nanobubbles, depending on process operating conditions. Nanobubbles also significantly improved process sepn. efficiency. Other major advantages of the nanobubble flotation process include lower frother dosage and air consumption since nanobubbles are produced from air naturally dissolved in water, thereby resulting in considerably lower operating costs.
- 16Ahmadi, R.; Khodadadi, D. A.; Abdollahy, M.; Fan, M. Nano-microbubble flotation of fine and ultrafine chalcopyrite particles. Int. J. Min. Sci. Technol. 2014, 24, 559– 566, DOI: 10.1016/j.ijmst.2014.05.021There is no corresponding record for this reference.
- 17Calgaroto, S.; Azevedo, A.; Rubio, J. Flotation of quartz particles assisted by nanobubbles. Int. J. Min. Process. 2015, 137, 64– 70, DOI: 10.1016/j.minpro.2015.02.01017https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXjtFGhu70%253D&md5=c94d209077569420ddeb5ad1f00b268bFlotation of quartz particles assisted by nanobubblesCalgaroto, S.; Azevedo, A.; Rubio, J.International Journal of Mineral Processing (2015), 137 (), 64-70CODEN: IJMPBL; ISSN:0301-7516. (Elsevier B.V.)Exptl. studies of flotation of quartz particles, under various conditions and cells (setups), are presented. Pure and well-characterized quartz samples were treated with a com. alkyl ether monoamine as flotation collector with bubbles in various sizes: coarse bubbles (400-800 μm); nanobubbles (200-720 nm); and their mixts. The nanobubbles were generated by selective sepn. from microbubbles, which are formed together after depressurizing-cavitation of the satd. water in air (as in pressure flotation or dissolved air flotation), at 66.1 psi satn. pressure. Flotation with single nanobubbles was not effective due to their very low lifting power or practically nil buoyancy. Yet, size-by-size flotation recoveries with coarse plus nanobubbles, compared with coarse bubbles, enhanced by 20-30 % the very fine quartz fractions by 20-30% (8-74 μm; Sauter diam.-D32) and slightly lowered the recoveries of coarse particles (67-118 μm; D32 diam.). Flotation of quartz samples (composites) having wide particle size distribution and results in a mech. cell validated the overall recovery enhancement of the fines. Fine particle capture (nanobubbles enhanced the contact angle of quartz) and aggregation of the quartz ultrafines (proved with micrographs) by the nanobubbles are the main mechanisms responsible for the higher recoveries. The effect on flotation of the coarser quartz fractions, at bench scale, may be explained in terms of a reduced rising velocity of the coarse bubbles, in the presence of nanobubbles, decreasing the degree of bubble carryover. It is expected that the use of collector-coated nanobubbles (tailor-made "bubble-collectors" and flocculants) will broaden options in fine mineral flotation. The future sustainable forms (cheaply produced) of nanobubble generation on a large scale and their injection in cells are envisaged.
- 18Azevedo, A.; Etchepare, R.; Calgaroto, S.; Rubio, J. Aqueous dispersions of nanobubbles: generation, properties and features. Miner. Eng. 2016, 94, 29– 37, DOI: 10.1016/j.mineng.2016.05.00118https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XovFWnurc%253D&md5=862d23ced08a777be8de2e9798e3747cAqueous dispersions of nanobubbles: Generation, properties and featuresAzevedo, A.; Etchepare, R.; Calgaroto, S.; Rubio, J.Minerals Engineering (2016), 94 (), 29-37CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)Nanobubbles (NBs) have interesting and peculiar properties such as high stability, longevity and high surface area per vol., leading to important applications in mining-metallurgy and environmental areas. NBs are also of interest in interfacial phenomena studies involving long-range hydrophobic attraction, microfluidics, and adsorption at hydrophobic surfaces. However, little data are available on effective generation of concd. NBs water dispersions and on their physicochem. and interfacial properties. In this work, air was dissolved into water at pH 7 and different pressures, and a flow was depressurized through a needle valve to generate 150-200 nm (mean diam.) NBs and MBs-microbubbles (about 70 μm). Microphotographs of the NBs were taken only in the presence of blue methylene dye as the contrast medium. Main results showed that a high concn. of NBs (no. per vol.) was obtained by decreasing the satn. pressure and surface tension. The no. of NBs, at 2.5 bar, increased from 1.0 × 108 NB mL-1 at 72.5 mN m-1 to 1.6 × 109 NB mL-1 at 49 mN m-1 (100 mg L-1 α-Terpineol). The NBs mean diam. and concn. only slightly varied within 14 days, which demonstrates the high stability of these highly concd. NBs aq. dispersions. Finally, after the NBs were attached to the surface of a grain of pyrite (fairly hydrophobic mineral), the NBs dramatically increased the population of MBs, which shows the enhancement of particle hydrophobicity due to NBs adhesion. The results were explained in terms of interfacial phenomena and it is believed that these tiny bubbles, dispersed in water at high concns., will lead to cleaner and more sustainable mineral flotation.
- 19Etchepare, R.; Oliveira, H.; Nicknig, M.; Azevedo, A.; Rubio, J. Nanobubbles: Generation using a multiphase pump, properties and features in flotation. Miner. Eng. 2017, 112, 19– 26, DOI: 10.1016/j.mineng.2017.06.02019https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFCrsLrO&md5=a6a5b2c60e31a3276900209bd00513ceNanobubbles: Generation using a multiphase pump, properties and features in flotationEtchepare, Ramiro; Oliveira, Henrique; Nicknig, Marcio; Azevedo, Andre; Rubio, JorgeMinerals Engineering (2017), 112 (), 19-26CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)The importance of nanobubbles is now widely known, particularly their applications and potential in mineral processing. The actual challenge is to generate a high concn. of bubbles (no. per water vol.) in a sustainable manner at high flow rates. The main objective of this work was to develop a new method for generating highly-loaded nanobubbles aq. solns. by hydrodynamic cavitation using a centrifugal multiphase pump (CMP) and a needle valve. Nanobubbles (150-200 nm) were formed, at 22°C, with the pump and a recycle column, at various operating pressures and air/liq. surface tension. Nanobubbles were resistant to shearing caused by pump impellers and to high operating pressures (up to 5 bar) throughout several bubble generation cycles. The size of the nanobubbles remained const., and their numeric concn. increased as a function of these cycles, reaching equil. after 29 cycles; this was dependent on pump pressure and the surface tension of the soln. The highest concn. (4 × 109 nanobubbles mL-1) was obtained at 5 bar and 49 mN m-1 surface tension (air holdup = 6.8% and D32 of microbubbles in the range between 62 and 70μm). These phenomena can be explained by Henry's Law and the lower energy required for bubble formation when the interfacial tension (air/water) decreases and when the differential pressure in the cavitation zone increases. The mean diam. and concn. of these nanobubbles did not vary significantly over a period of two months, demonstrating the high stability of these concd. nanobubbles. It is concluded that the procedure has great potential in future applications in ore flotation and wastewater treatment and reuse.
- 20Rosa, A. F.; Rubio, J. On the role of nanobubbles in particle–bubble adhesion for the flotation of quartz and apatitic minerals. Miner. Eng. 2018, 127, 178– 184, DOI: 10.1016/j.mineng.2018.08.02020https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsFGqsb%252FK&md5=ad7cee54d8b5557c3ca38e0b34a40a2eOn the role of nanobubbles in particle-bubble adhesion for the flotation of quartz and apatitic mineralsRosa, A. F.; Rubio, J.Minerals Engineering (2018), 127 (), 178-184CODEN: MENGEB; ISSN:0892-6875. (Elsevier Ltd.)This work evaluated the influence of nanobubbles (150-200 nm, mean diam.) on the visual adhesion of microbubbles (70 μm mean diam.) and macrobubbles (1 mm mean diam.) onto selected mineral particles (quartz and apatite) and on the flotation of both minerals, at bench scale. The adhesion of bubbles to high purity grains of quartz and apatite was monitored using a specially designed photog. technique. The results showed that the highest adhesion of bubbles onto the mineral grains occurred only after "conditioning" with nanobubbles. The nanobubbles appear to adhere to hydrophobic surfaces and confined to the rough surfaces of the grains, probably due to the dissipation of the free surface energy of the solids. As a result, the nanobubbles appear to serve as nuclei for enhanced adhesion of micro and/or macrobubbles, assisting the flotation of both minerals. In the case of quartz (D50 = 290 μm), the recovery increase was about 23% compared to a std. test of flotation with macrobubbles only. Furthermore, flotation kinetics was rapid and quartz recovery, at the first min, was double that obtained in the absence of nanobubbles. In the case of a fine apatitic ore (35% < 37 μm particles), best results were obtained with a combination of nano, micro and macrobubbles, with a 500-1000 g t-1 sapond. soybean oil collector and a 300-600 g t-1 gelatinized corn starch depressant of iron bearing minerals. The P2O5 recoveries increased about 9% compared to flotation with macrobubbles only, and sepn. also occurred at a higher rate. The total recovered phosphate (4 min std. test) was obtained in the first 1.5 min, after conditioning with nanobubbles, followed by injection of and microbubbles. Results validated the reported high potential for nanobubbles in "surface conditioning", the first stage of mineral flotation and were explained in terms of the soln. and interfacial phenomena involved.
- 21Craig, V. S. J.; Ninham, B. W.; Pashley, R. M. Effect of Electrolytes on bubble coalescence. Nature 1993, 364, 317– 319, DOI: 10.1038/364317a021https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXlsVOis7s%253D&md5=afddda175536ac1b0bd7645c677cf7e1Effect of electrolytes on bubble coalescenceCraig, V. S. J.; Ninham, B. W.; Pashley, R. M.Nature (London, United Kingdom) (1993), 364 (6435), 317-19CODEN: NATUAS; ISSN:0028-0836.The foaminess of ocean waves, relative to fresh water, has long been attributed to the effect of salts in reducing bubble coalescence. This phenomenon is exploited in extn. processes using froth flotation, in which the extn. efficiency increases as the bubble size gets smaller. But whereas the bubble-stabilizing effect of surfactants is well understood, the effect of salts is not; the fact that salts decrease the surface tension of water and that they are desorbed from the air-water interface would, if anything, be expected to destabilize bubbles. Here the authors report the results of expts. conducted to study the stabilization of bubbles by salts. Bubble coalescence is inhibited by some salts whereas others have no effect and this inhibition occurs only upon the matching of a 2-valued empirical property assigned to each anion and cation. The authors believe these observations can be explained only by the local influence of the ions on water structure, possibly in a way related to the hydrophobic interaction.
- 22Craig, V. S. J.; Ninham, B. W.; Pashley, R. M. The Effect of Electrolytes on Bubble Coalescence in Water. J. Phys. Chem. 1993, 97, 10192– 10197, DOI: 10.1021/j100141a04722https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXlvV2ls70%253D&md5=7ce7bbd1b65258b7352efabadbeee696The effect of electrolytes on bubble coalescence in waterCraig, Vincent S. J.; Ninham, Barry W.; Pashley, Richard M.Journal of Physical Chemistry (1993), 97 (39), 10192-7CODEN: JPCHAX; ISSN:0022-3654.Common electrolytes were found either to reduce the rate of bubble coalescence in water or to produce no effect. For a range of cations and anions, a system of combining rules emerges that characterizes the behavior of all the salts studied. The specific effects of electrolytes on bubble coalescence may be related to their effect on water structure and hence the hydrophobic interaction. The phenomenon may have applications in various fields, including decompression sickness, hydrophobic chromatog., and possibly biol. and evolution.
- 23Henry, C. L.; Craig, V. S. J. Inhibition of Bubble Coalescence by Osmolytes: Sucrose, Other Sugars, and Urea. Langmuir 2009, 25, 11406– 11412, DOI: 10.1021/la901535523https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXotVGktLo%253D&md5=cb1a4903a645e7b6ec7a9bbeee702439Inhibition of Bubble Coalescence by Osmolytes: Sucrose, Other Sugars, and UreaHenry, Christine L.; Craig, Vincent S. J.Langmuir (2009), 25 (19), 11406-11412CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Bubble coalescence inhibition by non-surface-active, nonelectrolytes urea and sucrose, and other small sugars, in aq. soln. is reported. Urea has no effect on bubble stability up to high concns. > 1 M, while sucrose inhibits coalescence in the range 0.01-0.3 M, similar to inhibiting electrolytes. Urea and sucrose both increase bubble coalescence inhibition in inhibiting and noninhibiting electrolytes in a cooperative manner, but urea decreases the efficacy of sucrose in mixed solns. Several mono- and disaccharides also inhibit bubble coalescence at ∼ 0.1 M, and the sugars vary in effectiveness. Disaccharides are more effective than the sum of their individual monosaccharide constituents, and sugars with very similar structures (for instance, diastereomers galactose and mannose) can show large differences in coalescence inhibition and hence thin film stability. Then it was concluded that solute charge is not required for bubble coalescence inhibition, which indicates that the mechanism is not one of electrostatic surface repulsion and instead an effect on dynamic film thinning other than Gibbs-Marangoni elasticity is implicated. Solute structure is important in detg. coalescence.
- 24Horn, R. G.; Ninham, B. W. Experimental studies of solvation forces in Micellar Solutions and Microemulsions. In Micellar Solutions and Microemulsions; Chen, S. H., Rajagopalan, A., Eds.; Springer-Verlag: New York; Chapter 5, 1990.There is no corresponding record for this reference.
- 25Pashley, R. M.; Ninham, B. W. Double-layer forces in ionic micellar solutions. J. Phys. Chem. 1987, 91, 2902– 2904, DOI: 10.1021/j100295a04925https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXitVagu7c%253D&md5=8ec962fb205255db856902ce3942b5a6Double-layer forces in ionic micellar solutionsPashley, R. M.; Ninham, B. W.Journal of Physical Chemistry (1987), 91 (11), 2902-4CODEN: JPCHAX; ISSN:0022-3654.Measurements are reported of the force between 2 mol. smooth mica surfaces coated with adsorbed bilayers of CTAB and sepd. by an aq. soln. of CTAB. Below the crit. micelle concn. (cmc), the double layer forces are well described by assuming the surfactant to be a completely dissocd. simple 1:1 electrolyte. Above the cmc, micelles and their "bound" counterions do not contribute to the Debye length. Some consequences for colloid stability are discussed.
- 26Fang, Z.; Wang, X.; Zhou, L.; Zhang, L.; Hu, J. Formation and Stability of Bulk Nanobubbles by Vibration. Langmuir 2020, 36, 2264– 2270, DOI: 10.1021/acs.langmuir.0c0003626https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXjs1KnsL4%253D&md5=c6246df18f3d01821cfb51d0e8cfb650Formation and Stability of Bulk Nanobubbles by VibrationFang, Zhou; Wang, Xingya; Zhou, Limin; Zhang, Lijuan; Hu, JunLangmuir (2020), 36 (9), 2264-2270CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Vibration is a very common process in nature, industry, biol., etc. Thus, whether vibration could induce the formation of nanoscale bubbles in water or not is very important for some chem. or biol. reactions. In this paper, we designed a control expt. to simulate the vibration process to explore the prodn. and stability of bulk nanobubbles. Exptl. results showed that the vibration could indeed induce the formation of a certain no. of bulk nanobubbles in water. In addn., the formation of bulk nanobubbles depended on the frequency and time of vibration. The existence of gas-liq. interface played an important role for the bulk nanobubbles formation because that external air is a possible important gas source. Our findings would be helpful to explore the mystical behavior of nanobubbles in natural processes.
- 27Bunkin, N. F.; Shkirin, A. V.; Suyazov, N. V.; Babenko, V. A.; Sychev, A. A.; Penkov, N. V.; Belosludtsev, K. N.; Gudkov, S. V. Formation and Dynamics of Ion-Stabilized Gas Nanobubble Phase in the Bulk of Aqueous NaCl Solutions. J. Phys. Chem. B 2016, 120, 1291– 1303, DOI: 10.1021/acs.jpcb.5b1110327https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVKiu7w%253D&md5=f7592b4ca20949b5aaaa942eb276828aFormation and Dynamics of Ion-Stabilized Gas Nanobubble Phase in the Bulk of Aqueous NaCl SolutionsBunkin, Nikolai F.; Shkirin, Alexey V.; Suyazov, Nikolay V.; Babenko, Vladimir A.; Sychev, Andrey A.; Penkov, Nikita V.; Belosludtsev, Konstantin N.; Gudkov, Sergey V.Journal of Physical Chemistry B (2016), 120 (7), 1291-1303CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)Ion-stabilized gas nanobubbles (the so-termed "bubstons") and their clusters are investigated in bulk aq. solns. of NaCl at different ion concns. by four independent laser diagnostic methods. It turned out that in the range of NaCl concn. 10-6 < C < 1 M the radius of bubston remains virtually unchanged at a value of 100 nm. Bubstons and their clusters are a thermodynamically nonequil. phase, which has been demonstrated in expts. with magnetic stirrer at different stirring rates. Different regimes of the bubston generation, resulting from various techniques of processing the liq. samples, were explored.
- 28Yurchenko, S. O.; Shkirin, A. V.; Ninham, B. W.; Sychev, A. A.; Babenko, V. A.; Penkov, N. V.; Kryuchkov, N. P.; Bunkin, N. F. Ion-Specific and Thermal Effectsin the Stabilization of the Gas NanobubblePhase in Bulk Aqueous Electrolyte Solutions. Langmuir 2016, 32, 11245– 11255, DOI: 10.1021/acs.langmuir.6b0164428https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtVKisrnN&md5=8ad80ac979799820fb1a360f9a6c19a5Ion-Specific and Thermal Effects in the Stabilization of the Gas Nanobubble Phase in Bulk Aqueous Electrolyte SolutionsYurchenko, Stanislav O.; Shkirin, Alexey V.; Ninham, Barry W.; Sychev, Andrey A.; Babenko, Vladimir A.; Penkov, Nikita V.; Kryuchkov, Nikita P.; Bunkin, Nikolai F.Langmuir (2016), 32 (43), 11245-11255CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Ion-stabilized nanobubbles in bulk aq. solns. of various electrolytes were studied. To understand the ion-specific mechanism of nanobubble stabilization, an approach based on the Poisson--Boltzmann equation at the nanobubble interface and in the near-surface layer was developed. The stabilization of nanobubbles is realized by the adsorption of chaotropic anions at the interface, whereas the influence of cosmotropic cations is weak. With increasing temp., it should be accounted for by blurring the interface due to thermal fluctuations. As a result, the adsorbed state of ions becomes unstable: the nanobubble loses its stability and vanishes. This prediction was proven in the authors' expts. In the case of liq. samples being kept in hermetically sealed ampuls, where the phase equil. at the liq.-gas interface is fulfilled for any temp., the vol. no. d. of nanobubbles decreases with increasing temp. and this decrease is irreversible.
- 29Bunkin, N. F.; Ninham, B. W.; Ignatiev, P. S.; Kozlov, V. A.; Shkirin, A. V.; Starosvetskij, A. V. Long-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensions. J. Biophotonics 2011, 4, 150– 164, DOI: 10.1002/jbio.20100009329https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3M7mt1ynug%253D%253D&md5=2de243fb40db7eaf4f3be4663c60593cLong-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensionsBunkin Nikolai F; Ninham Barry W; Ignatiev Pavel S; Kozlov Valery A; Shkirin Alexey V; Starosvetskij Artem VJournal of biophotonics (2011), 4 (3), 150-64 ISSN:.Results of experiments combining laser modulation interference microscopy and Mueller matrix scatterometry show that macroscopic scatterers of light are present in liquids free of external solid impurities. Experimental data on distilled water and aqueous NaCl solutions of various concentrations as well as physiological saline solution are reported. The experimental data can be interpreted by using a model of micron-scale clusters composed of polydisperse air nanobubbles having effective radii of 70-100 nm. Their concentration increases with the growth of ionic content. We hypothesize that under certain conditions those clusters of nanobubbles can affect the erythrocyte structure.
- 30Bunkin, N. F.; Shkirin, A. V.; Kozlov, V. A.; Starosvetskiy, A. V. Laser scattering in water and aqueous solutions of salts. Laser Applications in Life Sciences , 2010; Vol. 7376, p 73761D.There is no corresponding record for this reference.
- 31Marâechal, Y. The Hydrogen Bond and the Water Molecule, The Physics and Chemistry of Water, Aqueous and Bio Media; Elsevier: Amsterdam, The Netherlands, 2007.There is no corresponding record for this reference.
- 32Bunkin, N. F.; Shkirin, A. V.; Lyakhov, G. A.; Kobelev, A. V.; Penkov, N. V.; Ugraitskaya, S. V.; Fesenko, E. E., Jr. Droplet-like heterogeneity of aqueous tetrahydrofuran solutions at the submicrometer scale. J. Chem. Phys. 2016, 145, 184501, DOI: 10.1063/1.496618732https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhvVehtLfF&md5=b1bf0da6bf31abbc2e9ce83f687320f8Droplet-like heterogeneity of aqueous tetrahydrofuran solutions at the submicrometer scaleBunkin, N. F.; Shkirin, A. V.; Lyakhov, G. A.; Kobelev, A. V.; Penkov, N. V.; Ugraitskaya, S. V.; Fesenko, E. E.Journal of Chemical Physics (2016), 145 (18), 184501/1-184501/11CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)A droplet formation in aq. solns. of THF (THF) was exptl. detected at the submicrometer scale using two independent laser diagnostic techniques (dynamic light scattering and laser phase microscopy) and described in terms of THF-water intermol. hydrogen bonding. The nanodroplets have a mean size of 300 nm, their refractive index is higher than that of the ambient liq., and they are highly enriched with THF mols. The max. of light scattering intensity falls within the THF concn. range 2-8 mol. %, which corresponds to the vol. no. d. of the nanodroplets ∼1010-1011 cm-3. A theor. explanation of forming the nanodroplets with a high content of THF, which is based on a model of dichotomous noise being applied to the so-termed "twinkling" hydrogen bonds and involves spinodal decompn. in the unstable region enclosed within the dichotomous binodal, is proposed. The parameters of hydrogen bonds in the mol. system "water-THF" were found, and the phase diagram of the soln. with allowance for crosslinking hydrogen bonds was constructed. (c) 2016 American Institute of Physics.
- 33Bunkin, N. F.; Lyakhov, G. A.; Shkirin, A. V.; Krivokhizha, S. V.; Afonin, A. A.; Kobelev, A. V.; Penkov, N. V.; Fesenko, E. E., Jr. Laser Diagnostics of the Mesoscale Heterogeneity of Aqueous Solutions of Polar Organic Compounds. Phys. Wave Phen. 2018, 26, 21– 35, DOI: 10.3103/s1541308x18010041There is no corresponding record for this reference.
- 34Françon, M. La granularite laser (spekle) et ses applications en optique; Masson: Paris, New York, 1978.There is no corresponding record for this reference.
- 35Jadhav, A. J.; Barigou, M. Bulk Nanobubbles or Not Nanobubbles: That is the Question. Langmuir 2020, 36, 1699– 1708, DOI: 10.1021/acs.langmuir.9b0353235https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVaqsrc%253D&md5=8f6e0a838c8bd8243e3ea5050095b7d0Bulk Nanobubbles or Not Nanobubbles: That is the QuestionJadhav, Ananda J.; Barigou, MostafaLangmuir (2020), 36 (7), 1699-1708CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Bulk nanobubbles are a novel nanoscale bubble system with unusual properties which challenge our understanding of bubble behavior. Because of their extraordinary longevity, their existence is still not widely accepted as they are often attributed to the presence of supramol. structures or contaminants. Nonetheless, bulk nanobubbles are attracting increasing attention in the literature, but reports generally lack objective evidence that the obsd. nano-entities are indeed nanobubbles. In this paper, we use various phys. and chem. anal. techniques to provide multiple evidence that the nano-entities produced mech. in pure water by a continuous high-shear rotor-stator device or acoustic cavitation and spontaneously by water-ethanol mixing are indeed gas-filled domains. We est. that the results presented here combined provide conclusive proof that bulk nanobubbles do exist and they are stable. This paper should help close the debate about the existence of bulk nanobubbles and, hence, enable the scientific community to rather focus on developing the missing fundamental science in this area.
- 36Malyuchenko, N. V.; Tonevitskii, A. G.; Savvateev, M. N.; Bykov, V. A.; Moisenovich, M. M.; Agapov, I. I.; Kozlovskaya, N. V.; Arkhipova, V. S.; Yegorova, S. G.; Kirpichnikov, M. P. Study of the structural features of proteins by intermittent-contact atomic force microscopy. Biophysics 2003, 48, 772– 778There is no corresponding record for this reference.
- 37Subramanian, D.; Boughter, C. T.; Klauda, J. B.; Hammouda, B.; Anisimov, M. A. Mesoscale Inhomogeneities in Aqueous Solutions of Small Amphiphilic Molecules. Faraday Discuss. 2013, 167, 217– 238, DOI: 10.1039/c3fd00070b37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2crltVWqtw%253D%253D&md5=f7ed45a8be4963ababc6eaf6b1ce91beMesoscale inhomogeneities in aqueous solutions of small amphiphilic moleculesSubramanian Deepa; Boughter Christopher T; Klauda Jeffery B; Hammouda Boualem; Anisimov Mikhail AFaraday discussions (2013), 167 (), 217-38 ISSN:1359-6640.Small amphiphilic molecules, also known as hydrotropes, are too small to form micelles in aqueous solutions. However, aqueous solutions of nonionic hydrotropes show the presence of a dynamic, loose, non-covalent clustering in the water-rich region, This clustering can be viewed as "micelle-like structural fluctuations". Although these fluctuations are short ranged (approximately 1 nm) and short lived (10 ps-50 ps), they may lead to thermodynamic anomalies. In addition, many experiments on aqueous solutions of hydrotropes show the occasional presence of mesoscale (approximately 100 nm) inhomogeneities. We have combined results obtained from molecular dynamics simulations, small-angle neutron scattering, and dynamic light-scattering experiments carried out on tertiary butyl alcohol (hydrotrope)-water solutions and on tertiary butyl alcohol-water-cyclohexane (hydrophobe) solutions to elucidate the nature and structure of these inhomogeneities. We have shown that stable mesoscale inhomogeneities occur in aqueous solutions of nonionic hydrotropes only when the solution contains a third, more hydrophobic, component. Moreover, these inhomogeneities exist in ternary systems only in the concentration range where structural fluctuations and thermodynamic anomalies are observed in the binary water-hydrotrope solutions. Addition of a hydrophobe seems to stabilize the water-hydrotrope structural fluctuations, and leads to the formation of larger (mesoscopic) droplets. The structure of these mesoscopic droplets is such that they have a hydrophobe-rich core, surrounded by a hydrogen-bonded shell of water and hydrotrope molecules. These droplets can be extremely long-lived, being stable for over a year. We refer to the phenomenon of formation of mesoscopic droplets in aqueous solutions of nonionic hydrotropes containing hydrophobes, as mesoscale solubilization. This phenomenon may represent a ubiquitous feature of nonionic hydrotropes that exhibit clustering in water, and may have important practical applications in areas, such as drug delivery, where the replacement of traditional surfactants may be necessary.
- 38Hand, D. B. The refractivity of protein solutions. J. Biol. Chem. 1935, 108, 703– 70738https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaA2MXisFOqsw%253D%253D&md5=3005a512f19a98d173e94bb1e3013f0fRefractivity of protein solutionsHand, David B.Journal of Biological Chemistry (1935), 108 (), 703-7CODEN: JBCHA3; ISSN:0021-9258.By extrapolation of nps - ns. = a C to solns. contg. only protein values for np, the refractivity of the pure protein in the dissolved state, are calcd. These values are proposed as an empirical convenience for describing the rate with which the refraction of protein solns. changes with concn. when the refractivity of the solvent is taken into consideration, thus permitting comparison of one protein with another. The sp. refractive increment, a, is not characteristic of the protein, but varies with the refractivity of the solvent. Values for np are given for serum globulin, urease, serum albumin, horse hemoglobin, ovalbumin, edestin, gliadin, globin, salmine, ovomucoid, casein, paranuclein and ovovitellin.
- 39Kimura, H. Light-scattering properties of fractal aggregates: numerical calculations by a superposition technique and the discrete-dipole approximation. J. Quant. Spectrosc. Radiat. Transfer 2001, 70, 581– 594, DOI: 10.1016/s0022-4073(01)00031-039https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXltFOjur4%253D&md5=82de557514d87483e129a1f6316ff5d5Light-scattering properties of fractal aggregates: numerical calculations by a superposition technique and the discrete-dipole approximationKimura, H.Journal of Quantitative Spectroscopy & Radiative Transfer (2001), 70 (4-6), 581-594CODEN: JQSRAE; ISSN:0022-4073. (Elsevier Science Ltd.)Dust particles in space often grow by mutual collisions and appear to be an agglomeration of individual grains, the morphol. of which can be described by the concept of fractals. The authors study light scattering by fractal aggregates of identical spheres (monomers) using the superposition technique incorporated into the T-matrix method where the orientationally averaged scattering matrix is anal. obtained. The authors also apply the discrete-dipole approxn., in which the dipole polarizability of spherical monomers is detd. by the 1st term of the scattering coeffs. in the Mie theory. Two cases of the ballistic aggregation process (particle-cluster and cluster-cluster aggregations) are considered to model fractal aggregates consisting of silicate or C material. The dependences of light-scattering properties on the monomer sizes, aggregate structures and material compns. are intensively studied. The light-scattering properties of the fractal aggregates strongly depend on the size parameters of the monomers. The difference in the scattering function between the particle-cluster and cluster-cluster aggregates can be seen in the case of monomers much smaller than the wavelength of incident radiation. When the size parameter of monomers exceeds unity, the material compn. of the monomers influences the light-scattering properties of the aggregates, but different morphologies result in similar scattering and polarization patterns. Silicate aggregates consisting of submicron-sized monomers, irresp. of the aggregate size and morphol., produce a backscattering enhancement and a neg. polarization obsd. for dust in the solar system.
- 40Mishchenko, M. I.; Travis, L. D.; Lacis, A. A. Scattering, Absorption, and Emission of Light by Small Particles; Cambridge University Press: Cambridge, 2002.There is no corresponding record for this reference.
- 41Feder, J. Fractals; Springer: New York, 1988.There is no corresponding record for this reference.
- 42Tazaki, R.; Tanaka, H.; Okuzumi, S.; Kataoka, A.; Nomura, H. Light scattering by fractal dust aggregates. I. Angular dependence of scattering. Astrophys. J. 2016, 823, 70, DOI: 10.3847/0004-637x/823/2/70There is no corresponding record for this reference.
- 43Cumper, C. W. N. The stabilization of foams by proteins. Trans. Faraday Soc. 1953, 49, 1360– 1369, DOI: 10.1039/tf953490136043https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaG2cXksVygtg%253D%253D&md5=f67618374847c94dcb0b9f30251cea1cStabilization of foams by proteinsCumper, C. W. N.Transactions of the Faraday Society (1953), 49 (), 1360-9CODEN: TFSOA4; ISSN:0014-7672.Three cryst. proteins (bovine β-globulin, pepsin, and insulin) stabilize the dispersion of air in water, as shown by passing air continuously through a protein soln. The av. life of individual bubbles formed under the surface of protein solns. and under spread protein monolayers was detd. The effects of changing the protein concn., pH, and ionic strength of the solns. were studied and the results correlated with previous observations on the mech. properties of films of the same proteins. Considerable variations were found in the life-times of individual bubbles. The mean of about 10 results was always taken, and the time from successive expts. fell within 10% on either side of their av. The behavior is consistent with protein adsorption occurring in 3 stages: adsorption, surface denaturation, and coagulation. Only surface-denatured protein is effective in stabilizing the air bubbles.
- 44Saint-Jalmes, A.; Peugeot, M.-L.; Ferraz, H.; Langevin, D. Differences between protein and surfactant foams: Microscopic properties, stability and coarsening. Colloids Surf., A 2005, 263, 219– 225, DOI: 10.1016/j.colsurfa.2005.02.00244https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXltlaisbw%253D&md5=b6071e8850051cde547ffbb485049856Differences between protein and surfactant foams: Microscopic properties, stability and coarseningSaint-Jalmes, A.; Peugeot, M.-L.; Ferraz, H.; Langevin, D.Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2005), 263 (1-3), 219-225CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Results are presented on foamability, stability and coarsening of foams made either of surfactant (SDS) or of milk protein (casein) solns. Studies were performed at the scales of the gas-liq. interface, thin liq. film and bubble size, to find the correlations between these different scales, and to elucidate the microscopic origins of the macroscopic features. For both systems, foamability concn. thresholds were measured, and a bubble size dependence was found. A clear correlation between the stability of an isolated thin film and the foam stability is always evidenced. However, the mechanism of stability of the casein thin films is different from the surfactant one, and related to the confinement and percolation of casein aggregates. The authors also report results on coarsening at const. liq. fraction, showing that the protein foams coarsen more slowly than the surfactant ones, and that it is due to differences in thin film thickness.
- 45Bunkin, N. F.; Shkirin, A. V.; Penkov, N. V.; Chirikov, S. N.; Ignatiev, P. S.; Kozlov, V. A. The Physical Nature of Mesoscopic Inhomogeneities in Highly Diluted Aqueous Suspensions of Protein Particles. Phys. Wave Phenom. 2019, 27, 102– 112, DOI: 10.3103/s1541308x19020043There is no corresponding record for this reference.
- 46Roitt, I. Essential Immunology; Blackwell Scientific Publications: Oxford, 1994.There is no corresponding record for this reference.
- 47Zetasizer Nano Series. User Manual. MAN0317 Issue 3.1 July 2007, Chapter 6. Sample Preparation; Malvern Instruments Ltd.: United Kingdom, 2007.There is no corresponding record for this reference.