On the operating efficiency of Helmholtz resonators in dead-end waveguides using fluid working media

An experimental study is presented of Helmholtz resonators in a dead-end waveguide representing a real hydraulic system with a centrifugal pump. With the example of the discrete spectrum components of the hydrodynamic noise of the waveguide under consideration, it is shown that the application of resonators can both reduce and increase noise levels.     

Surface Activity of sp-Metals in Molten Intermetallic Compounds

The dependence of the surface-layer composition of a molten binary intermetallic compound (IMC) on factors determining electrochemical properties of liquid electrodes in indifferent electrolytes is studied. The segregation of the binary melt components at the interface with vacuum is considered in terms of physical materials technology. The interface state of the molten IMC is described by the Landau–Ginzburg functional for a surface excess of the Gibbs free energy. An examination of the functional shows that a minimum energy at a given temperature and system volume is reached by depositing the component with the lowest surface tension at the plain component's mp on the melt surface. The deposit has the character of a mesophase; therefore, it remains liquid at temperatures much lower than the plain component's mp in the bulk phase. The dilation interactions between atoms near the interface, caused by different atomic volumes of components, favor the deposition of the metal with a higher atomic volume. The calculated change of the surface tension of Ga–Tl IMC as related to plain Ga is close to relevant experimental value obtained on neutral Ga and Ga–Tl electrodes in an indifferent electrolyte.     

Adsorption Inversion on the Free Surface of the Melt of Binary Intermetallic Compound

The adsorption of components on the free surface of the melt of intermetallic compound was studied using the density functional theory. The conditions, which allow for the adsorption inversion upon changing the melt composition, were discussed. The data obtained were used for interpreting the electrocapillary dependences of amalgam electrodes.     

Cluster aspects of binary and ternary fission

On the basis of the statistical approach and calculation of the potential energy of the scission configurations, binary and ternary fissions are described. The text was submitted by the authors in English     

Small angle neutron scattering setup for high pressure measurements at IBR-2

Abstract

The experiments which were carried out showed the possibility of using a titanium-zirconium high pressure cell for small angle neutron scattering. We report on some curves measured by SANS with the help of this setup to illustrate the capabilities of the method.     

Structure of organosilicon dendrimers of higher generations

The structure of organosilicon dendrimers of the ninth generation with the four-functional core and butyl terminal groups has been studied by small-angle neutron scattering. It has been demonstrated that the dendrimers are monodisperse objects with an anisometric shape. The partial volume and the average scattering density have been determined using the contrast variation technique. It has been shown that the dendrimers under study are identical in overall sizes and scattering density distribution. It has been revealed that 20% of the overall volume of the dendrimer is accessible for the penetration of the solvent. The distribution of the scattering length density in the dendrimers has been simulated and reconstructed using the Monte Carlo method, and a change in the excluded volume for different contrasts has been revealed. The specific features of the spatial structure of organosilicon dendrimers of higher generations have been discussed.     

Partial charge transfer during the specific adsorption of halide anions on a metal electrode

The partial charge transfer from (to) an anion specifically adsorbed on an uncharged interphase boundary between a metal electrode and an electrolyte solution was studied. The energy of the system was presented as a quadratic functional in the orders of perturbation of the electron densities of the anion and metal. The linear terms of the expansion represent the traditional contribution to the energy term of the chemical potentials of separated starting subsystems. The quadratic terms describe the influence of the chemical hardnesses on the equilibrium bonding energy. Based on the condition of minimum of the energy functional expressions for the partial charge transfer, energy of stabilization, and adsorption bond length were obtained. The results were used to estimate the parameters of the chemisorption bonding of halide anions to a mercury electrode and to interpret experimental data on the properties of the interphase boundary between a mercury electrode and an alkali halide solution in water and acetonitrile. It was demonstrated that the formulas derived satisfactorily describe the key parameters of the bond even in the zeroth-order approximation.     

Evolutionary Algorithm-Based Crystal Structure Prediction for Copper(I) Fluoride

Despite numerous experimental studies since 1824, the binary copper(I) fluoride remains unknown. A crystal structure prediction has been carried out for CuF using the USPEX evolutionary algorithm and a dispersion-corrected hybrid density functional method. In total about 5000 hypothetical structures were investigated. The energetics of the predicted structures were also counter-checked with local second-order Møller–Plesset perturbation theory. Herein 39 new hypothetical copper(I) fluoride structures are reported that are lower in energy compared to the previously predicted cinnabar-type structure. Cuprophilic Cu−Cu interactions are present in all the low-energy structures, leading to ordered Cu substructures such as helical or zig-zag-type Cu−Cu motifs. The lowest-energy structure adopts a trigonal crystal structure with space group P3₁21. From an electronic point of view, the predicted CuF modification is a semiconductor with an indirect band gap of 2.3 eV.