Thermodynamics of Liquid–Liquid Criticality in Supercooled Water in a Mean-Field Approximation

In a recent publication, it has been shown how a non-analytic scaling theory of critical phenomena can describe the available experimental information for the thermodynamic properties of supercooled water, when it is assumed to exhibit a liquid–liquid critical point. In this article, we present a mean-field equation of state which also represents the experimental data for supercooled water. Compared to the scaling theory, the mean-field equation has the advantage of simplicity for practical calculations of the properties of supercooled water. The insensitivity to a particular form of a critical equation of state is due to a lack of experimental data asymptotically close to the liquid–liquid critical point. Hence, while the assumed existence of a liquid–liquid critical point in water can account for the observed thermodynamic behavior of supercooled water, the actual location of such a liquid–liquid critical point cannot be determined accurately from the available experimental thermodynamic property data.     

Investigation of the Ice–Water Vapor Equilibrium Along the Sublimation Line

An accurate knowledge of the thermodynamic properties of water at low temperature plays an important role in atmospheric processes, chemical physics, and metrological applications. Preliminary investigations of the water vapor?Cice equilibrium along the sublimation line have been carried out at Istituto Nazionale di Ricerca Metrologica (INRIM). The measurements covered the temperature range from ?50?°C to 0?°C, corresponding to a saturation vapor pressure from about 4?Pa to 611?Pa. The measurements were performed using a small gold-plated cell kept in a liquid bath at a constant temperature with millikelvin stability. The sample cell was connected to a manifold where the pressure was measured using two capacitive diaphragm pressure gauges. The paper reports the water sample preparation, measuring method, and measurement corrections. Measurement results are discussed and uncertainty sources estimated. The resulting expanded relative uncertainty (k = 2) varies from 0.038 % at 0?°C to 0.70 % at ?50?°C.     

A–BTransition of Superfluid 3He with a Film Geometry

We have performedcwNMR experiments on superfluid ³ He confined to a parallel-plate geometry with a m scale spacing for a wide pressure range. A static field was applied parallel or perpendicular to the plate surface. The spectra of two absorption signals, a main and a satellite, have been observed below the superfluid transition temperature in a parallel field. As the temperature decreased, the main signal decreased with shifts to higher frequencies, and the satellite grew with shifts to much higher frequencies. From the temperature dependence of these signals and the result in the perpendicular field, it is confirmed that the main signal and the satellite correspond to the A phase signal (ABM state) and the B phase signal (BW state), respectively. The temperature dependence of the two signals indicates that a phase transition from the A phase to the B phase occurs with decreasing temperature. By analyzing these signals, we determine A–B transition temperatures experimentaly. TheA–Btransition temperature normalized by the superfluid transition temperature is 0.95 at 20 bar, and decreased further to 0.70 at 0 bar for a thickness of 0.88 m for pure ³ He. The values of T_AB/T_C were slightly elevated when covering the surface with 4.5 layers of ⁴ He film, which suggests that this transition is also influenced by the surface condition.     

Synthesis of Porous Tungsten from Tungsten–Cadmium Film Coatings

Solid solutions (alloys) with a Cd concentration of 50.3–76.3 at % were synthesized for the first time in the form of coatings by ion–plasma sputtering and codeposition of ultrafine W and Cd particles. When coatings were formed by tungsten and cadmium nanolayers, the components dissolved mutually to produce solid solutions of one metal in the other. A solid solution of cadmium in tungsten was synthesized at Cd concentrations up to 60.9 at %. At a cadmium concentration of 68.6 at % in the coating, the crystalline structure of cadmium with an admixture of amorphous tungsten was produced. At 800°C, tungsten evaporated from tungsten–cadmium coatings to form porous tungsten. The results of examination of materials fabricated on the basis of porous tungsten are planned to be used in practice.     

Surface Reaction of TiAl with Water Vapor and Oxygen

The interaction of water vapor and oxygen with TiAI-based alloy has been studied with Auger electron spectroscopy and X-ray photoelectron spectroscopy. The results indicate that both surface reactions initiate at a very short exposure (about 6×10-7 Pa·s) and the oxides Al2O3 and TiO2 form in the surface reactions. In the oxidizing reaction, the water vapor reacts firstly with Al, and then reacts with Ti after certain exposure. The surface reaction of Al with water vapor may be responsible for the environmental embrittlement at room temperature in TiAI-based alloy.     

Ginzburg–Landau Simulation of Superconducting Matter in a Semicircular Film

We numerically investigate the superconductor matter of a film type-II superconductor with circular geometry numerically in a computational simulation using the link variable method to solve the time dependent Ginzburg–Landau equation. We apply the implemented algorithm to a half circular film surrounded by a thin layer of another superconductor at a higher critical temperature. The film is immersed in an external magnetic field applied perpendicularly to its plane. The boundary condition is taken into account with the de Gennes extrapolation length b. We calculate the magnetization, vortex number, the third critical thermodynamical field as a function of the external magnetic field, and the b parameter. We find that for these interfaces the third critical field $H_{\mathrm{c}_{3}}$ and the magnetization M are largely increased.     

Control of the Properties of Thin‐Film Systems with the Use of Pulsed Photon Treatment

We have developed a radically new technological process of making very largescale integrated circuits, which has no analogs and is based on the use of fast heat treatments for forming gettering layers, silicon oxidation, annealing of iondoped layers, fusion of phosphoro and borophosphorosilicate glasses, forming silicides, and increasing the thermostability of aluminum metallization.     

Specific Features of Peroxide Precipitation of Uranium from Acid Water–Ethanol Solutions

Radiochemistry - Effect of acidity and hydrogen peroxide and ethanol concentrations on the degree of precipitation of uranium peroxide in solutions of various compositions was studied. The...     

Calculation of Diffusional Transfer of Water‐Soluble Compounds with Account for Sorption Kinetics

Based on computational experiments, approximate formulas and nomograms are suggested for calculation and evaluation of the processes of diffusional transfer of watersoluble compounds under conditions of contact of two semiinfinite media.     

Calculation of Convective Transfer of Water‐Soluble Compounds with Account for Sorption Kinetics

An asymptotic solution is obtained for the equation of convective diffusion of watersoluble compounds with account for sorption kinetics with the linear isotherm of the sorption of them by a solid disperse phase. It is shown that the hydrodispersion is proportional to the squared linear velocity of a liquid flow and is inversely proportional to the masstransfer coefficient which determines the rate of establiment of the sorption equilibrium.     

Mathematical Model of Oil Displacement by Water with the Use of Polymer‐Disperse Systems

A mathematical model describing the process of displacement of oil by water with the use of polymerdisperse systems is proposed. The point of the technology consists of pumping sequentially water, a lowconcentration polymer solution, and water with disperse particles. The porous medium is given in the form of two interpenetrating continua, one of which is associated with mobile phases and the other — with immobile phases. The corresponding expressions for dynamic porosity and the residual resistance factor have been obtained. In describing the mass transfer between the continua, an ideal model of a porous medium in the form of a bundle of capillaries of different radii and the pore and particlesize distribution functions have been used.     

Fundamental Perspectives on the Electrochemical Water Applications of Metal–Organic Frameworks

Metal–organic frameworks(MOFs), a family of highly porous materials possessing huge surface areas and feasible chemical tunability, are emerging as critical functional materials to solve the growing challenges associated with energy–water systems, such as water scarcity issues. In this contribution, the roles of MOFs are highlighted in electrochemical-based water applications(i.e., reactions, sensing, and separations), where MOF-based functional materials exhibit outstanding performances in dete...     

Distinctive Features of Water–Dimethyl Sulfoxide Mixtures: Dielectric Spectra Revisited

Broadband dielectric spectra (1 MHz to 80 GHz) are reported for dimethyl sulfoxide–water mixtures in the complete composition range. The spectra are evaluated in order to yield information about the underlying relaxation time distribution, the principal relaxation time, and the static permittivity of the liquids. With a view of gaining insights into the structure and microdynamics of water in its different states of interaction, these parameters are compared to such for mixtures of water with other protic and aprotic dipolar liquids as well as with non-polar substances. Also used for information about structure fluctuations are ultrasonic spectra of the dimethyl sulfoxide–water system (0.2 MHz to 2.75 GHz). A notable result is the composition dependence of the principal dielectric relaxation time. In conformity with the wait-and-switch model, it increases at low DMSO content and thus reflects the decrement in the concentration of hydrogen-bonding sites. The decreasing relaxation time at high DMSO content is clearly a result of the reduced association due to the reduced concentration of hydrogen-donating sites.     

Speed of Sound of a Bose–Einstein Condensate with Dipole–Dipole Interactions

In the present work the case of a chromium Bose–Einstein condensate is considered. The model includes not only the presence of the so-called contact interaction but also a long range and anisotropic dipole–dipole interaction has been included. Some thermodynamical properties are analyzed. For instance, the size of the condensate, chemical potential, speed of sound, number of particles, etc., are deduced. It will be shown that this dipole–dipole interaction implies the emergence of anisotropy, for example, in the speed of sound. The possible use of this anisotropy as a tool for the analysis of dissipative mechanisms, for instance, Landau’s criterion for superfluidity, will be also discussed.     

Interaction of Water with GeCl4 , SnCl4 , and AsCl3

The interaction of water with GeCl₄, SnCl₄, and AsCl₃ was studied by IR spectroscopy. The results demonstrate that these chlorides contain molecular water in monomeric form. At water concentrations above 10^–2 mol/l, GeCl₄ also contains H₃O⁺ ions. The mechanisms of GeCl₄ and AsCl₃ hydrolysis were studied over a wide range of water concentrations.