Dynamics of gas bubble growth in a supersaturated solution with Sievert's solubility law

This paper presents a theoretical description of diffusion growth of a gas bubble after its nucleation in supersaturated liquid solution. We study systems where gas molecules completely dissociate in the solvent into two parts, thus making Sievert's solubility law valid. We show that the difference between Henry's and Sievert's laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that diffusion flux is steady we obtain a differential equation on bubble radius. Bubble dynamics equation is solved analytically for the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop. We also obtain conditions of diffusion flux steadiness. The fulfillment of these conditions is studied for the case of nucleation of water vapor bubbles in magmatic melts.Comment: 22 pages, 3 figure

Viscoelasticity and metastability limit in supercooled liquids

A supercooled liquid is said to have a kinetic spinodal if a temperature Tsp exists below which the liquid relaxation time exceeds the crystal nucleation time. We revisit classical nucleation theory taking into account the viscoelastic response of the liquid to the formation of crystal nuclei and find that the kinetic spinodal is strongly influenced by elastic effects. We introduce a dimensionless parameter \lambda, which is essentially the ratio between the infinite frequency shear modulus and the enthalpy of fusion of the crystal. In systems where \lambda is larger than a critical value \lambda_c the metastability limit is totally suppressed, independently of the surface tension. On the other hand, if \lambda < \lambda_c a kinetic spinodal is present and the time needed to experimentally observe it scales as exp[\omega/(\lambda_c-\lambda)^2], where \omega is roughly the ratio between surface tension and enthalpy of fusion

Heat transfer under high-power heating of liquids. 1. Experiment and inverse algorithm

A new approach to fluids behavior study in the course of highpower heating has been developed by us. The approach combines experimental method of controlled pulse heating of a wire probe and numerical method of thermophysical properties temperature dependencies recovery from the experimental data. Short (millisecond) characteristic time scale allows working with short-lived fluids, including superheated (with respect to the liquid-vapor equilibrium temperature and/or to the temperature of thermal decomposition onset) ones. Numerical method gives a set of inverse heat conduction problem solutions, based on the results of single pulse experiment. Numerical technique, based on the heat transfer parameters optimization model, is built using genetic algorithms. The approach was applied to saturated hydrocarbons in the temperature range 300-625 K. © 2013 Elsevier Ltd. All rights reserved

NMR Studies of Lithium Diffusion in Li3(NH2)2I over Wide Range of Li+ Jump Rates

We have studied the Li diffusion in the complex hydride Li3(NH2)2I which appears to exhibit fast Li ion conduction. To get a detailed insight into the Li motion, we have applied 7Li nuclear magnetic resonance spectroscopy methods, such as spin-lattice relaxation in the laboratory and rotating frames of reference, as well as spin-alignment echo. This combined approach allows us to probe Li jump rates over the wide dynamic range (~102–109 s−1). The spin-lattice relaxation data in the range 210–410 K can be interpreted in terms of a thermally-activated Li jump process with a certain distribution of activation energies. However, the low-temperature spin-alignment echo decays at T≤200 K suggest the presence of another Li jump process with the very low effective activation energy. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017

Anomaly in the stability limit of liquid helium 3

We propose that the liquid-gas spinodal line of helium 3 reaches a minimum at 0.4 K. This feature is supported by our cavitation measurements. We also show that it is consistent with extrapolations of sound velocity measurements. Speedy [J. Phys. Chem. 86, 3002 (1982)] previously proposed this peculiar behavior for the spinodal of water and related it to a change in sign of the expansion coefficient alpha, i. e. a line of density maxima. Helium 3 exhibits such a line at positive pressure. We consider its extrapolation to negative pressure. Our discussion raises fundamental questions about the sign of alpha in a Fermi liquid along its spinodal.Comment: 5 pages, 3 figure

Promoting Persistent Superionic Conductivity in Sodium Monocarba-closo-dodecaborate NaCB11H12 via Confinement within Nanoporous Silica

Superionic phases of bulk anhydrous salts based on large cluster-like polyhedral (carba)borate anions are generally stable only well above room temperature, rendering them unsuitable as solid-state electrolytes in energy-storage devices that typically operate at close to room temperature. To unlock their technological potential, strategies are needed to stabilize these superionic properties down to subambient temperatures. One such strategy involves altering the bulk properties by confinement within nanoporous insulators. In the current study, the unique structural and ion dynamical properties of an exemplary salt, NaCB11H12, nanodispersed within porous, high-surface-area silica via salt-solution infiltration were studied by differential scanning calorimetry, X-ray powder diffraction, neutron vibrational spectroscopy, nuclear magnetic resonance, quasielastic neutron scattering, and impedance spectroscopy. Combined results hint at the formation of a nanoconfined phase that is reminiscent of the high-temperature superionic phase of bulk NaCB11H12, with dynamically disordered CB11H12-anions exhibiting liquid-like reorientational mobilities. However, in contrast to this high-temperature bulk phase, the nanoconfined NaCB11H12 phase with rotationally fluid anions persists down to cryogenic temperatures. Moreover, the high anion mobilities promoted fast-cation diffusion, yielding Na+ superionic conductivities of similar to 0.3 mS/cm at room temperature, with higher values likely attainable via future optimization. It is expected that this successful strategy for conductivity enhancement could be applied as well to other related polyhedral (carba)borate-based salts. Thus, these results present a new route to effectively utilize these types of superionic salts as solid-state electrolytes in future battery applications

ОРГАНИЗАЦИЯ ПСИХОСОМАТИЧЕСКОЙ ПОМОЩИ ПАЦИЕНТАМ С КАРДИОЛОГИЧЕСКОЙ ПАТОЛОГИЕЙ

Introduction. The prevalence of mental disorders, especially anxious and depressive calculi, among cardiac patients is significant. There is no doubt that it affects the cardiovascular system. The objective of the study was to analyze the prevalence of anxiety and depressive disorders among patients with cardiac pathology in the large hospital; and also to assess the provision of patients with this pathology with psychosomatic beds. Material and methods. In the course of the study, a questionnaire was conducted among 264 patients in the large cardiology department in St. Petersburg. The respondents were asked general and specialized (HADS questionnaire – screening for anxiety and / or depression) questions. With the help of special formulas on the basis of the received data, the required number of psychosomatic beds and regular positions of psychotherapists for the treatment of psychosomatic pathology for the city of St. Petersburg was calculated. Results. The findings confirmed the presence of a significant proportion of anxiety and / or depressive disorders among patients with diseases of the circulatory system. In addition to objective data, a significant percentage of interviewed patients associate the development of the underlying disease with emotional stress. Special attention is required by the age group of 60–75 years and older; men and women equally. It is important to note that the specific weight of clinically expressed forms is significant. This group of patients needs psychotherapeutic treatment in addition to the therapy of cardiac disease, which the respondents admit. Conclusions. Despite such a significant relevance, the organization of medical care for these patients in St. Petersburg is not enough. The perspectives of solving the problem were determined: an increase of stuff psychotherapists in multidisciplinary hospitals, integration of psychotherapeutic care into the outpatient stage of treatment.Актуальность. Распространённость психических расстройств, особенно тревожного и депрессивного спектра, среди кардиологических пациентов значительна. Не вызывает сомнений её влияние на заболевания сердечно-сосудистой системы. Цель исследования – проанализировать распространенность тревожных и депрессивных расстройств среди пациентов с кардиологической патологией крупного стационара; а также оценить обеспеченность пациентов с данной патологией койками психосоматического профиля. Материал и методы. В ходе исследования было проведено анкетирование среди 264 пациентов крупного кардиологического отделения г. Санкт-Петербурга. Респондентам были заданы общие и специализированные (анкета HADS – скрининг на наличие тревоги и/или депрессии) вопросы. С помощью специальных формул на основании полученных данных был произведен расчёт потребного количества психосоматических коек и штатных должностей психотерапевтов для лечения психосоматической патологии для города Санкт-Петербурга. Результаты исследования. Полученные данные подтвердили наличие весомой доли тревожных и/или депрессивных расстройств среди пациентов с болезнями системы кровообращения. Помимо объективных данных, значимый процент опрошенных пациентов связывают развитие основного заболевания с эмоциональными нагрузками. Особого внимания требует возрастная группа 60–75 лет и старше; мужчины и женщины в равной степени. Важно отметить, что значителен удельный вес клинически выраженных форм. Данная группа пациентов нуждается в психотерапевтическом лечении помимо терапии кардиологического заболевания, что признают и сами респонденты. Заключение. Несмотря на столь значимую актуальность, организация медицинской помощи данным пациентам в городе Санкт-Петербурге недостаточна. Определены перспективы решения проблемы: увеличение штата врачей-психотерапевтов в многопрофильных стационарах, интеграция психотерапевтической помощи в амбулаторный этап лечения

Cavitation Inception on Microparticles: A Self-Propelled Particle Accelerator

Corrugated, hydrophilic particles with diameters between 30 �m and 150 �m are found to cause cavitation inception at their surfaces when they are exposed to a short, intensive tensile stress wave. The growth of cavity and its interaction with the original nucleating particle is recorded by means of digital imaging. The growing cavity accelerates the particle into translatory motion until the tensile stress decreases, and subsequently the particle separates from the cavity. The cavity growth and particle detachment are modeled by considering the momentum of the particle and the displaced liquid. The analysis suggests that all particles which cause cavitation are accelerated into translatory motion, and separate from the cavities they themselves nucleate

Intensification of heat transfer during spinodal decomposition of a superheated aqueous oligomer solution

The heat conduction of an aqueous solution of polypropylene glycol in the region of stable and unstable states was studied by the method of pulse isothermal impact on a substance with a characteristic time of 100 ms. It has been shown that the short-Term superheating of a homogeneous solution not only above the liquid-liquid equilibrium temperature (low critical solution temperature), but also above the diffusion spinodal is fundamentally possible. The negative character of the deviation of the heat conduction of a solution from the additive law calculated from the heat conduction of the pure components at a given temperature was revealed. The signs of manifestation of spinodal decomposition accompanied by a significant intensification of heat transfer were found. © Published under licence by IOP Publishing Ltd

THERMOPHYSICAL MONITORING OF MOISTURE IN HYDRAULIC LIQUIDS

The technique of fast thermal control has been applied for the examination of samples of hydraulic liquids with a water content from 0,1 to 3,5 %. Appropriate operating modes of the measuring device were found.Работа выполнена в рамках проекта РФФИ № 16-08-00381 и проекта комплексной программы Уральского отделения РАН № 18-2-2-3