L. L. Chaikov

Nanoscale metal oxide particles produced in the plasma discharge in the liquid phase upon exposure to ultrasonic cavitation. 1. Method for producing particles

It is shown that a new form of the plasma discharge with bulk glow throughout the space between electrodes and an descending current-voltage characteristic, occurring in liquid in an ultrasonic field with an intensity above the cavitation threshold, can be efficiently used to initiate the various physical and chemical processes. In such an acoustic plasma discharge, nanoparticles of oxides of various metals, i.e., aluminum, copper, tin, iron, titanium, indium, zinc, molybdenum, and others, are synthesized with controllable particle shape and size and narrow size distribution. Micrographs of some nanoparticles are presented. The difference in luminescence of particles produced in the absence and presence of cavitation is shown.

Nanoscale metal oxide particles produced in the plasma discharge in the liquid phase upon exposure to ultrasonic cavitation. 2. Sizes and stability. Dynamic light scattering study

Size distributions of tungsten oxide particles produced in the plasma discharge in the liquid phase upon exposure to ultrasound were studied by the dynamic light scattering method. Particles produced by this method under ultrasonic cavitation (USC), in the absence of cavitation, and without cavitation followed by ultrasonic processing are compared. The behavior of concentrations of particles of various size groups is comparatively estimated by the data on particle sizes and scattering intensity using the Rayleigh-Gans-Debye approximation. It is shown that ultrasonic processing improves the aggregative stability of suspension; in a suspension of particles produced under USC, large aggregates eventually decay into individual small particles.

Correlation spectroscopy measurements of particle size using an optical fiber probe

We propose measuring the size of particles suspended in a liquid by light beating spectroscopy of scattered light using an optical fiber probe inserted into a medium and consisting of three multimode optical fibers. One of them is used to transmit light, the other two — to transmit scattered light to a unit providing its spatial coherence and further to a photodetector. In very turbid media, the multiple-to-single light-scattering spectral line width ratio is determined by the ratio of line widths in two collecting optical fibers. Then the particle size is determined by the spectrum of multiple rather than single scattering.

Dynamics of statistically confident particle sizes and concentrations in blood plasma obtained by the dynamic light scattering method

Abstract. The work is devoted to the study of sizes and concentrations of proteins, and their aggregates in blood plasma samples, using static and dynamic light scattering methods. A new approach is proposed based on multiple repetition of measurements of intensity size distribution and on counting the number of registrations of different sizes, which made it possible to obtain statistically confident particle sizes and concentrations in the blood plasma. It was revealed that statistically confident particle sizes in the blood plasma were stable during 30 h of observations, whereas the concentrations of particles of different sizes varied as a result of redistribution of material between them owing to the protein degradation processes.

Stimulated concentration (diffusion) light scattering on nanoparticles in a liquid suspension

A nonlinear growth of the light scattering intensity has been observed and the frequency shift of the spectral line of scattered light has been measured in light backscattered in suspensions of diamond and latex nanoparticles in water. The shift corresponds to the HWHM of the line of spontaneous scattering on particles. We may conclude that there exists stimulated concentration (diffusion) light scattering on variations of the particle concentration, which is also called the stimulated Mie scattering. In a fibre probe scheme, the growth of the shift of the scattered spectral line is observed with an increase in the exciting beam power. The variation of the frequency shift with an increase in the exciting power is explained by convection in liquid.

Detection of various phases in liquids from the hypersound velocity and damping near closed phase-separation regions of solutions

Theoretical analysis revealed that experimental results obtained in our studies on hypersound propagation in a guaiacol-glycerol solution in the vicinity of the closed phase-separation region, double critical point, and special point, as well as the origin of these regions, can be explained by the presence of two different phases (I and II) of the solution with phase-transition temperature T0. Temperature T0 coincides with the temperature at the center of closed phase-separation regions, as well as with the double critical point and with the special point. In (Frenkel) phase I, molecules are in potential wells whose depth exceeds the thermal energy of a molecule, while thermal energy in (gaslike) phase II is higher than the potential well depth. At the lower critical point, the thermodynamic potential of phase I is equal to the thermodynamic potential of the phase-separated solution. At the upper critical point, the thermodynamic potential of phase II is equal to the thermodynamic potential of the phase-separated solution. The observed broad dome of the hypersound absorption coefficient near T0 can be explained by the contribution associated with fluctuations of the order parameter corresponding to the transition from phase I to phase II. The difference in the temperature coefficients of hypersound velocity on different sides of T0 and some other effects are also explained.

Effect of iron oxide nanoparticles on the concentration-versus-sizes relation of proteins in the blood plasma and serum, and in model solutions

The effect of iron (III) oxide nanoparticles produced in acoustoplasma discharge with cavitation on the concentration and the sizes of particles in model protein solutions, human blood serum and plasma samples is studied. Dynamic and static light scattering data on size and concentration of particles show that the nanoparticles addition to fibrinogen-thrombin system affects the course of enzymatic reaction. Interaction of nanoparticles with fibrinogen solution (before thrombin addition) does not significantly change the distribution of scattered light intensity on particle sizes. Comparison of the relations of particle sizes and their concentration for fibrinogen solution with and without nanoparticles shows an increase of the slope of size-concentration relation in a log-log scale, which indicates an increase in the concentration of small particles and decrease of big ones. For model solution of fibrinogen with thrombin, initially incubated with iron oxide nanoparticles, the slopes of the size-concentration relation equals to k = –(4.62±0.33) and slightly differs from the slope of the relation for fibrinogen-thrombin system without nanoparticles k=–(4.23±0.28). We believe that changes in the size-concentration relation indicate the interaction of nanoparticles with proteins, which results in gelation rate change.

Study of the Interaction between Iron Oxide Nanoparticles, Produced in Acoustoplasma Discharge with Cavitation, and Blood Plasma Fibrinogen by Light Scattering Techniques

Interactions between iron oxide nanoparticles, produced in acoustoplasma discharge with cavitation, and blood plasma fibrinogen is studied in a model solution by dynamic light scattering. Depending on the storage time of the nanoparticles, their interaction with the protein shows different dynamics of the size distribution. However, the biological action of the nanoparticles is the same regardless of the storage time, i.e., they act as inhibitors of the reaction of fibrin gel formation.

Luminescence properties of nanoparticles synthesized in electric discharge in liquid under ultrasonic cavitation

The differences in the luminescence intensity of metal oxide nanoparticles synthesized in electric discharges in liquidmedia under intense ultrasonic vibrations in the absence and presence of cavitation are studied.

Effect of ultrasonic cavitation on dynamics and characteristics of electric discharge in liquid

Characteristics of electric discharges in liquid media under intense ultrasonic vibrations are studied. The difference in current dynamics and discharge voltages in the presence and in the absence of cavitation is shown.