The specific features of clustering in the aqueous solutions of monohydric alcohols with concentrations higher than that at the peculiar point are discussed. Clustering is a result of the formation of hydrogen bonds between water and alcohol molecules, the energy of which somewhat exceeds the energy of hydrogen bonds in the water-water and alcohol-alcohol molecular pairs. Elementary clusters are assumed to be formed, whose composition is fixed at the solution concentrations lower than that at the peculiar point and changes according to a certain law at higher concentrations. The solution clustering degree was determined as a function of the solution concentration and the temperature.K e y w o r d s: solutions, water, monohydric alcohols, elementary clusters, peculiar point. IntroductionThe properties of aqueous monohydric alcohol solutions differ substantially from the properties of ideal solutions [1][2][3]. This difference reveals itself in the optical properties of solutions, in particular, in the appearance of maxima in the abnormal light scattering [4][5][6], in the form of the concentration and temperature dependences of the adiabatic compressibility [7] and the heat capacity [8], in the emergence of large relaxation times [2,9] and other features in the volumetric behavior of those solutions [10,11], in particular, their contraction [12][13][14].The first models of solutions as associated systems were developed by D.I. Mendeleev more than 150 years ago after the systematic studies of clustering in water-alcohol solutions [15]. This concept was developed and detailed in further researches, both experimental and theoretical ones, which had been reflected in a number of reviews [1,16]. In particular, Scatchard [17], using thermodynamic methods, studied the volume change at the solution formation from its components.In works [12][13][14], the manifestation of clustering in the behavior of the simplest solution characteristic,

A relation between the water properties and the behavior of aqueous solutions of albumin, the main protein component of human blood plasma, has been analyzed. The dependence of the pH index of acid-base balance in aqueous albumin solutions on the albumin concentration is experimentally studied. It is shown that the temperature dependences of pH in biological solutions are determined by the properties of water, and the concentration ones by the concentration of a protein component. It is albumin that makes the main contribution to the pHs of blood and blood plasma, and it should be considered as a factor that maintains the equilibrium pH value. It is shown that the most characteristic changes in the concentration dependences of the density and shear viscosity of human plasma occur at a protein concentration corresponding to the percolation threshold. A characteristic dimerization of albumin macromolecules is assumed to take place at the percolation threshold, which corresponds to the superposition on one another of heart-shaped medallions representing the spatial forms of albumin. The dependences of the effective radii of polyvinyl alcohol and albumin macromolecules on the solution temperature and concentration are demonstrated to be an indicator that water plays a decisive role in the formation of basic properties of biosolutions. In particular, it is responsible for the presence of an upper temperature limit of 42 ∘C for the existence of living matter. The universal nature of the water influence manifests itself in that the water properties affect the behavior of both the classic PVA polymer and protein biomolecules.

Non-trivial properties of thermodynamic quantities such as the density, the critical and triple point temperatures, and their ratio, as well as the optical and dielectric properties, have been analyzed for primary alcohols from the methanol series. The aim is to reveal relationships among their values measured at the same temperatures for alcohols with different ordinal numbers m’s in the methanol series. It is shown that the non-monotonic character of the temperature dependences of alcohol densities is associated with methanol rather than ethanol, as may seem at first glance. The critical temperature of methanol also deviates from the quasilinear dependence of the critical alcohol temperatures on m. With the growing m, the ratio between the critical and triple-point temperatures for alcohols is shown to tend to the corresponding value for water. Simple linear dependences of the electronic and effective static polarizabilities of alcohol molecules on m are established. The transverse and longitudinal components of the polarizability tensor for alcohol molecules are found. The dipole moments of the closest neighbor molecules in the alcohols are proved to anticorrelate, i.e. to orient in opposite directions.

The density and shear viscosity of human blood plasma and their dependence on the concentration of proteins (albumin, y-globulin, fibrinogen, etc.) entering the natural blood composition have been studied. The biomaterial concentration is varied by diluting the blood plasma with the isotonic aqueous solution. It is shown that a decrease in the biomaterial concentration down to 0.91 of its initial value leads to a drastic change in the plasma density and to a change in the character of the concentration dependence of the shear viscosity of blood plasma. A hypothesis is put forward that the observed changes in the density and shear viscosity result from the structural transformations induced by oligomerization processes; first of all, by the albumin dimerization. A conclusion is drawn that the introduced blood substitutes should not exceed 10% of the blood mass; otherwise, structural transformations of a biomaterial in blood plasma can be provoked.