Moscow University Chemistry Bulletin最新文献

The development of efficient and environmentally friendly thermoelectric materials for mid-temperature applications, in the range of 200–500°С, follows the necessity to create devices for saving electricity, and in particular, for converting waste heat into electric power. This review surveys the evolution of thermoelectric materials from the initial approaches of Abram Ioffe to modern ideas using the examples of various substances including chalcogenides, pnictides, and intermetallic compounds. Special attention is paid to the implementation of new concepts for the development of thermoelectric materials from inexpensive and environmentally friendly substances for mid-temperature applications, primarily in the automotive industry.

In this short review, we attempt to analyze and summarize the existing trends related to the development of solid-state polymer-based electrolytes for lithium-ion batteries. Mechanisms of the ion conductivity and modern approaches to the optimization of solid polymer electrolytes and creation of composite polymer electrolytes are considered. The possible promising approaches to the development of efficient solid-state polymer electrolytes are assessed.

This review addresses the issue of efficient and selective extraction of uranium(VI) from various media using systems based on ionic liquids. It examines the current technological process for extracting uranium(VI) from spent nuclear fuel solutions and identifies its shortcomings. This review analyzes and systematizes information on the main types of ionic liquids being studied for uranium(VI) extraction, either as solvents, extractants, or in their pure form. Special attention is given to commercially available ammonium and phosphonium ionic liquids, which have demonstrated high efficiency in extracting uranium(VI) from hydrochloric and alkaline media, while in nitric acid media, the highest distribution coefficients are observed for tetravalent actinides [1].

Aromatic and, in peculiar, polyaromatic hydrocarbons are one of the common class of anthropogenic pollutants. Processes of their degradation are of great interest from an ecological point of view. This article describes the current situation in the use of ultrasound as an instrument, accelerating such degradation.

The reasons for discordance data on the contribution of a TUBB3 microtubule protein to resistance to antitumor drugs and the metastatic potential of tumors with an assessment of prognostic significance of TUBB3 expression in nonsmall cell lung cancer tissue are analyzed. The need to introduce quantitative analysis methods in molecular diagnostics of tumors (in particular, immunofluorescence assessment associated with flow cytometry) is substantiated.

The study of ytterbium halide crystals using the compound-tunable embedding potential (CTEP) method is carried out in the framework of the density functional theory. For subsequent calculations the optimization of atomic bases is carried out, and for this purpose stoichiometric molecular systems were studied, using the coupled-cluster methods. The chemical shift of the lines of the X-ray emission spectrum, K_α1 and K_α2, in YbHal₃ relative to YbHal₂ was chosen as a criterion for verifying the computational accuracy of the properties localized on the nucleus of a heavy atom, Yb, since this method is a unique tool for analyzing partial electron densities near a heavy nucleus specifically for compounds of d- and f-elements. In the study, five main versions for the halogen basis set sizes were considered. The stability of the results was obtained using the CCSD and CCSD(T) coupled cluster methods for molecular systems YbF₂, YbF₃, YbCl₂ and YbCl₃.

The multireference configuration interaction method based on single and double excitations (MR–CISD), l-independent core polarization potential (CPP), and diffuse function-saturated cc-pVQZ and aug-cc-pV5Z basis sets for Na and He atoms, respectively, is used to perform nonrelativistic calculations of potential energy curves and permanent dipole moment functions for the ground and excited electronic states of the exciplex Na–He molecule up to the Na(6²S) state. The ab initio results obtained within a wide range of internuclear distances R [1.7, 20.0] (Å) quantitatively confirm the undulating behavior of interatomic potentials, predicted in the framework of the inelastic scattering theory. It is established that at large R the interatomic potentials and dipole moments of highly excited (3, 6, 10)²Σ⁺ states, converging to the Na (n = 4, 5, 6²S) + He(2²S) atomic limits, are modulated by the nodal structure of the radial Rydberg wave function (n > 3) of the s-electron of an Na atom during its scattering on a remote He atom.

Gcn5-related N-acetyltransferases catalyze the transfer of an acetyl group to a primary amino group of a wide class of substrates. Deprotonation of the amino group upon binding to the enzyme is necessary to activate the nucleophilic attack on the substrate. The process of binding of glutamate to N-acetylglutamate synthase is considered using the methods of molecular modeling and quantum chemistry. It is shown that deprotonation of the primary amino group of glutamate occurs upon its incorporation into the active site of the enzyme with the participation of the side chain of the aspartate residue.

The possibility of the elution of hydrophilic organophosphorus substances using a concentration gradient of formic acid in an aqueous mobile phase on a Hypercarb porous graphitized carbon sorbent is studied. The analytes are detected on a monoquadrupole mass spectrometer. The retention of analytes is studied by varying the composition of the mobile phase before injection of the sample solution. It is shown that the effect of the stepwise gradient elution on the retention of analytes is primarily due to the state of the sorbent surface rather than the elution ability of the phases. The displacement “quasi-ion exchange” mechanism of analyte retention seems to be most probable.

Based on the solution of the direct vibrational-rotational problem with the Watson Hamiltonian using Van Vleck perturbation theory, employing the quantum-chemical (CCSD(T)/aug-cc-pVQZ) molecular geometry of molecule ({text{D}}_{2}^{{16}}{text{O}}), sextic force field, and cubic dipole moment surface, absorption spectra and spectroscopic constants of effective rotational Hamiltonians (A-reduction) for the ground state and ν₂ band are predicted. Theoretical sixth-order vibrational (fourth for dipole operators) and third-order rotational perturbative methods are based on a systematic procedure for calculating rotational commutators using the normal ordering of cylindrical angular momentum operators. The obtained reduced spectroscopic constants are refined and augmented by being fitted into sets of experimental energy levels. The new effective Hamiltonians significantly improve the reproduction of the experimental data for J ≤ 30, and the computed intensities accurately reproduce the observed values.