Hyper-Cross-Linked Polystyrene as a Stabilizing Medium for Small Metal Clusters

Among different polymers nanostructured cross-linked aromatics have the greatest potential as catalytic supports due to their exceptional thermal and chemical stability and preservation of the active phase morphology. This work studies the ability of hyper-cross-linked polystyrene (HPS) to stabilize small Pd_n and Pt_n (n = 4 or 9) clusters. Unrestricted DFT calculations were carried out for benzene (BZ) adsorption at the BP level of theory using triple-zeta basis sets. The adsorption of BZ rings (stepwise from one to four) was found to result in noticeable gain in energy and stabilization of resulting adsorption complexes. Moreover, the interaction of metal clusters with HPS micropores was also addressed. For the first time, the incorporation of small clusters in the HPS structure was shown to influences its geometry resulting in the stabilization of polymer due to its partial relaxation.     

Experimental determination of the electron screening potential energy for the d(d, n)3He Reaction in ZrD2 and D2O in the ultralow energy region

This work is devoted to measuring of the values of the astrophysical S-factors and electron screening potential energy for a d(d,n)³He reaction occurring at ultralow energies in zirconium deuteride ZrD₂ (3.5–7.0 keV) and heavy water D₂O (2.2–6.0 keV). The experiment was performed on the Hall pulsed plasma accelerator at the TPU Nuclear Physics Institute (Tomsk) with ZrD₂ and D₂O targets produced by the magnetron sputtering of zirconium in a deuterium environment and heavy water freezing-out on a copper support, respectively. A χ ² analysis of the dependence of the neutron yields and astrophysical S-factors for the dd reaction on the deuteron collision energy E revealed that the upper bounds of the electron screening potential energy for interacting deuterons in ZrD₂ and D₂O and of the astrophysical S-factors at the deuteron collision energy E = 0 were U _e (ZrD₂) < 30 eV, U _e (D₂O) < 25 eV, S(0) = (57.2 ± 3.9) keV · b (ZrD₂), S(0) = (58.6 ± 3.6) keV · b (D₂O) at the 90% confidence level.     

Modeling of the energy spectrum of the CdTe/Hg1-xCdxTe/CdTe quantum well by varying the band offset, well width, and composition x

Currently, CdTe/Cd _x Hg_1-x Te/CdTe heterostructures attract particular interest and are very promising for developing the next-generation terahertz radiation detectors. However, properties of such structures have not yet been studied in sufficient detail. The energy spectrum and wave functions of the CdTe/Cd _x Hg_1-x Te/CdTe heterostructure were theoretically modeled for various well widths, the valence band offset, and composition x in the range 0<x<0.16. Characteristic features of the behavior of energy levels of two-dimensional electrons in such structures were studied with respect to x variation. A criterion for determining the number of electronic levels below the conduction band bottom, applicable to compositions 0<x<0.16 was obtained. The time of two-dimensional electron relaxation by longitudinal optical phonons was calculated.     

Synthesis,Spectral, and Coordination Properties of Halogen-Substituted Tetraarylporphyrins

2,3,7,8,12,13,17,18-Ocatbromo-5,10,15,20-tetra-(4-chloroprienyl)porphyrin and 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(4-bromophenyl)porphyrin have been synthesized. The obtained compounds have been identified by electronic absorption and ¹H NMR spectroscopy as well as mass spectrometry. The complex-forming properties of the synthesized porphyrins in the zinc acetate (II)-acetonitrile system at 278–298 K have been studied. Kinetic parameters of the formation of the corresponding zinc complexes in acetonitrile have been determined.

     

Preparation and Properties of Interpolymer Complexes Capable of Soil Structuring

Complexation between biopolymers, chitosan cationic polyelectrolyte and sodium carboxymethyl cellulose anionic polyelectrolyte, was studied. The composition of the interpolymer complex formed was determined by conductometry and Fourier IR spectroscopy. The interpolymer complex and the initial complex-forming polymers were used for the first time as soil-structuring agents in urban soils. Treatment of urban soil with the interpolymer complex led to aggregation of soil particles and improved the water permeability of the soil.

     

Production of Adsorption Materials from Bentonite Clay Containing an Organic Dye

Russian Journal of Applied Chemistry - Carbon-containing materials were produced from a mixture of bentonite clay and Crystal Violet dye adsorbed on the clay. X-ray diffraction analysis and IR...     

Effect of the dynamical collision frequency on quantum wakefields

Previous papers on the quantum wakefield around an ion moving in a dense plasma have considered the collision frequency in the static approximation. In this work, we present the results of the dynamically screened ion potential taking into account the dynamical electron–ion collision frequency. The Lenard–Balescu dynamical collision frequency and various approximations to it are considered. As a main result of our investigation for the subsonic, sonic, and supersonic regimes, we find that the frequency dependence of collisions can be safely discarded if the electronic streaming velocity (relative to an ion) is comparable to or less than the electronic Fermi velocity.     

Study of background processes with the formation of neutrons in nuclear reactions in the energy range of 26–32 kev

The nature of background processes accompanying astrophysical nuclear reactions induced by hydrogen, helium, and neon ions in deuterated targets with small cross sections has been studied in calculations and experiments. The experiments have been performed at a Hall pulsed plasma accelerator in the ion energy range of 26–32 keV. The yield of background neutrons and γ-quanta with energies below 4 MeV in the proton-induced D(p, γ)³He reaction is primarily due to the presence of a natural impurity of gaseous deuterium in gaseous hydrogen and the chain of D(D, ³He)n → (n, γ) or (n, n'γ) reactions. A small contribution comes from the chain of D(¹H, ¹H)D → D(D, ³He)n → (n, γ) or (n, n'γ) reactions. It has been shown that background neutrons and γ-quanta from the D(4He, γ)6Li reaction are entirely due to the chain of D(⁴He, ⁴He)D → D(D, ³He)n → (n, γ) or (n, n'γ) reactions. It has been shown that the yield of neutrons and γ-ray photons detected at the interaction of neon ions with deuterated targets is also entirely due to the chain of elastic- scattering reactions of neon ions on deuterons in the target and to subsequent inelastic processes of interaction of deuterons accelerated at elastic scattering with other deuterons of the target. The main contribution to the yields of background neutrons and γ-quanta comes from doubly charged neon ions. The main conclusion is that the explanation of the yield of neutrons and γ-quanta at the interaction of hydrogen, helium, and neon ions with deuterated targets does not require “exotic” theoretical models.     

Shear elasticity and strength of the liquid structure by an example of diethylene glycol

Experimental data for the dependence of the low-frequency (10⁵ Hz) shear elasticity of diethylene glycol on the shear deformation angle have been presented. At small shear angles, the range of linear elasticity has been observed, which narrows with rising strain. The effective viscosity behaves similarly.     

Quality of Speech Reproduction Using Stochastic Digital Systems of Information Transfer with its Statistical Compaction

Russian Physics Journal - Quality of oral speech reproduction using stochastic digital systems of information transfer at its statistical compaction is analyzed (on the example of Russian and...