Stochastic approach to the theory of stratification of water and aqueous solutions: A model of twinkling hydrogen bonds

The equations of state for liquids and liquid solutions with intermolecular hydrogen bonds were derived in the dichotomous noise model for these bonds. The analytically obtained PT and TC phase diagrams show that finite-lifetime bonds can be responsible for new experimentally found phase transitions. These are (i) stratification of solutions in a closed TC region (i.e., a region with upper and lower critical points) and in a low-concentration TC region and (ii) low-temperature stratification of monomolecular liquids into heavy and light phases.     

Cluster structure of stable dissolved gas nanobubbles in highly purified water

Experiments using phase-modulation interference microscopy and Mueller-matrix polarimetry show that double-distilled water free of foreign solid matter contains macroscopic light scatterers. Numerical calculations suggest that these scatterers can be represented as micrometer-size clusters of polydisperse air bubbles with effective radii between 70 and 90 nm. The fractal dimension of the clusters varies from 2.4 to 2.8, and their concentration is on the order of 10⁶ cm^?3.     

Study of nanostructure of highly purified water by measuring scattering matrix elements of laser radiation

Experiments on modulation interference microscopy and measurement of light scattering matrix elements showed that double distilled water purified from solid impurities contains macroscopic scatterers of optical radiation. It follows from numerical calculation that these scatterers can be micrometer-scale clusters formed by polydisperse air bubbles with effective radii of 70 to 90 nm. The fractal dimension of such clusters is within 2.4–2.8 and their concentration is ∼ 10⁶ cm⁻³.     

The Physical Nature of Mesoscopic Inhomogeneities in Highly Diluted Aqueous Suspensions of Protein Particles

The dispersed composition of water samples prepared by the multiple-dilution technique has been investigated opto-physically using two laser diagnostics methods: dynamic light scattering and laser phase microscopy. We studied suspensions of antibodies (Ab) to the human interferon-gamma (IFNγ) in water with an initial concentration of 0.125 mg ml^?1 (5×10¹⁴ mol cm^?3), which were subjected to 12 successive 100-multiple volume dilutions (C12) in water. Individual antibodies and particles of about 300 nm in size, which can be considered as aggregates of individual antibodies, have been found in the initial suspensions. It turned out that some mesoparticles with a concentration on the order of 10³ cm^?3 exist also in suspensions subjected to C12 dilution. These particles have a refractive index close to typical values of protein refractive indices. A possible explanation of the origin of particles with sizes on the order of several hundreds of nanometers, revealed in highly diluted suspensions, is proposed. On the one hand, some of these particles may be aggregates of antibodies from the initial suspension, which remained (due to the flotation effect) in the bulk of the liquid after dilutions. On the other hand, the appearance of solid contaminant particles at the same mesoscopic scale (i.e., on the order of several hundreds of nanometers) cannot be excluded in the dilution process.

     

Laser diagnostics of the Bubston phase in the bulk of aqueous salt solutions

Stable gas nanobubbles in the bulk of NaCl aqueous solutions and clusters of these nanobubbles have been investigated at different ion concentrations by four independent laser techniques (phase microscopy, dynamic light scattering, optical breakdown, and measurement of angular dependences of the light scattering matrix). The results obtained by these radically different techniques are in good agreement. It is found that the nanobubble size is practically constant and amounts to approximately 100nm in the range of ion concentrations 10^?6<C <1M. It is shown that a necessary condition for nanobubble nucleation is the saturation of solution with dissolved air. It is revealed that nanobubble clusters form a thermodynamically nonequilibrium phase with a lifetime of several months.     

Nanobubble clusters of dissolved gas in aqueous solutions of electrolyte. I. Experimental proof

Results of experiments with dynamic light scattering, phase microscopy, and polarimetric scatterometry allow us to claim that long-living gas nanobubbles and the clusters composed of such nanobubbles are generated spontaneously in an aqueous solution of salt, saturated with dissolved gas (say, atmospheric air). The characteristic sizes of both nanobubbles and their clusters are found by solving the inverse problem of optical wave scattering in ionic solutions. These experimental results develop our earlier study reported by Bunkin et al. [J. Chem. Phys. 130, 134308 (2009)] and can be treated as evidence for the special role of ions in the generation and stabilization of gas nanobubbles.     

Mesodroplet Heterogeneity of Low-Concentration Aqueous Solutions of Polar Organic Compounds

It is found experimentally that a mesoscopic droplet phase is formed in low-concentration aqueous solutions of various polar organic compounds, which are considered in the chemical literature as infinitely soluble in water. The content of dissolved organic molecules in droplets is much higher than in the ambient solution. The droplet size increases with temperature. Theory can explain the mesodroplet formation by the phase separation of a binary mixture affected by the dichotomous noise of twinkling hydrogen bonds between molecules of organic compound and water. The Snyder polarity index, which is used by chemists as a miscibility criterion for molecular compounds, depends in the model on the dipole moments of mixed molecules and the energy and number of hydrogen bonds. With this refinement, it can be used as an estimation criterion for the existence and intensity (i.e., the number of droplets per unit volume of organic aqueous solution) of mesodroplet separation.

     

Time dependence of the luminescence from a polymer membrane swollen in water: Concentration and isotopic effects

The effect of UV irradiation of the surface of a Nafion polymer electrolyte membrane swollen in water in the pump grazing incidence geometry has been experimentally investigated. The photoluminescence from the Nafion surface has been measured in the spectral range characteristic of this polymer. The photoluminescence signal from a polymer with a variable isotopic composition is found to be sensitive to swelling in water. The spectral absorption lines of dry and water-swollen Nafion samples are characterized. It is shown that the luminescence centers in the polymer are sulfonic acid groups located on the ends of perfluorovinyl ether groups, which form the teflon base. Measurements of the temporal dynamics of the luminescence of these groups have revealed an informationally important and significant dependence of the luminescence parameters on the degree of Nafion swelling. A pronounced and nontrivial dependence of these parameters on the content of heavy isotope D₂O in water is also found.