Effect of oxygen on some reactions of ZnSe crystal surface interaction with H₂O vapors, CO₂, and CO

Effect of oxygen on some interaction reactions of ZnSe crystal surface with water vapors, CO₂, and CO which result in release of hydrogen, and also carbon from a surface of crystals is discussed. Temperature dependences of equilibrium constants are calculated. It is found that participation of oxygen into the viewed processes of interacting results in sharp increase of probability and intensity of their actual behavior. It was shown that the essential contribution to these processes can be made by presence of antropogenic admixtures in air (water, hydrocarbons, CO₂, CO, engine exhaust fumes, etc.) which plays a critical part in pollution of ZnSe crystals surface by carbon

Selection of Appropriate Quantum-Chemical Model for Calculations of Properties of Chromium Group Complexes via DFT

The selection of a pair of functional/basis for the most adequate quantum-chemical determination of the geometric and electronic properties of chromium group metal complexes with polydent heterocyclic ligands has been carried out. When selecting a suitable model, such parameters as allowable accuracy and acceptable time of calculation have been taken into account. It has been found that the accuracy of calculations depends on the number of basis functions in-volved in the calculation model – the error tends to decrease with the increase in their number. The ac-curacy of calculations also increases with introduction of the polarized orbitals 2d2p and 3df3pd in the quantum-chemical model and the diffuse orbitals p, pp, ppp in the basis, respectively. The results obtained by using non-hybrid functionals with large basis functions are comparable to the calculations performed in less time with the help of hybrid functionals. The optimal ratio for the accuracy of calculation results compared to the time for study of the coordi-nation compounds can be achieved by using the PBE0 hybrid functional and TZVPP basis functions

Carboxylate Phosphabetaines Containing Chiral Carbon Atom: Synthesis and NMR Spectroscopy Data

Abstract: The nucleophilic addition reactions of tertiary phosphines and unsaturated carboxylic acids have led to the formation of mono- and dicarboxylate phosphabetaines containing an asymmetric carbon atom. The data of 1D and 2D NMR spectroscopy have revealed the presence of diastereotopic geminal protons of the CH2 group adjacent to the chiral center in the obtained compounds. The values of spin-spin coupling constants of the vicinal hydrogen atoms have coincided with the dihedral angles values (X-ray diffraction analysis data). [Figure not available: see fulltext.

New biologically active phosphonium salts based on 3-(diphenylphosphino)propionic acid and unsaturated amides

© 2020, Springer Science+Business Media LLC. New carboxylate phosphabetaines were synthesized from 3-(diphenylphosphino)propionic acid and unsaturated amides. Alkylation of the synthesized carboxylate phosphabetaines with haloalkyles was studied. In vitro biological activity of the synthesized phosphonium salts was evaluated

New phosphonium salts based on 3-(diphenylphosphino)propanoic and ω-haloalkanoic acids

Quarternization of 3-(diphenylphosphino)propanoic acid with ω-haloalkanoic acids affords novel phosphonium salts containing two carboxy groups. The phosphonium salts were treated with 1 M alkali solution to obtain corresponding carboxylate phosphabetaines. The structure of the compounds was established by IR and NMR spectroscopy, elemental analysis and X-ray single crystal diffraction

Age-associated murine cardiac lesions are attenuated by the mitochondria-targeted antioxidant SkQ1

Age-related changes in mammalian hearts often result in cardiac hypertrophy and fibrosis that are preceded by inflammatory infiltration. In this paper, we show that lifelong treatment of BALB/c and C57BL/6 mice with the mitochondria-targeted antioxidant SkQ1 retards senescence-associated myocardial disease (cardiomyopathy), cardiac hypertrophy, and diffuse myocardial fibrosis. To investigate the molecular basis of the action of SkQ1, we have applied DNA microarray analysis. The global gene expression profile in heart tissues was not significantly affected by administration of SkQ1. However, we found some small but statistically significant modifications of the pathways related to cellto-cell contact, adhesion, and leukocyte infiltration. Probably, SkQ1-induced decrease in leukocyte and mesenchymal cell adhesion and/or infiltration lead to a reduction in age-related inflammation and subsequent fibrosis. The data indicate a causative role of mitochondrial reactive oxygen species in cardiovascular aging and imply that SkQ1 has poteential as a drug against age-related cardiac dysfunction

Long range effect in ion-implanted gaas

New experimental data are presented which indicate the change of defect centers concentration in GaAs at macroscopic (up to millimeters) distances from the implanted regions edge. These data were obtained by locally exited cathodoluminescence, by observation of photoconductivity detected locally by contactless MW technique, by conductivity, DLTS and Raman spectroscopy measurement. Interpretation of the mechanism of long range effect is presented. © 1993, Taylor & Francis Group, LLC. All rights reserved

Транскраниальная декомпрессия каналов зрительных нервов при менингиомах хиазмально-селлярной области: эффективность, риски и осложнения

The study objective is evaluate the effectiveness and risks of using intradural and extradural decompression of the optic nerve channels during standard transcranial removal of meningiomas of the chiasmal-cellar region region. Materials and methods. The results of 161 decompression of channel of optic nerve in 129 patients are analyzed. In most patients (n = 122), an intradural decompression (resection) of the canal roof was performed. In 7 patients, an extradural decompression of the upper and lateral walls of the canal was performed. Results. In assessing the risks of visual impairment as a result of channel decompression, we found that decompression itself, without attempts to separate the tumor from the nerve, causes vision impairment in 8.6 % of cases. Attempts to separate the tumor from the optic nerves increase the risk of vision impairment from 16.7 to 26.9 %, depending on the radicality. Conclusion. A small number of complications (iatrogenic amaurosis and nasal liquorrhea) make it possible to recommend the described technique as an effective and safe addition to standard transcranial operations to remove the meningiomas of the chiasmal-cellar region.Цель исследования - определить эффективность и безопасность интрадуральной и экстрадуральной декомпрессии канала зрительного нерва в ходе стандартной транскраниальной операции по удалению менингиомы хиазмально-селлярной области. Материалы и методы. Проанализированы результаты 161 декомпрессии канала зрительного нерва у 129 пациентов. У большинства пациентов (n = 122) выполняли интрадуральную декомпрессию (резекцию) крыши канала. У 7 пациентов провели экстрадуральную декомпрессию верхней и боковой стенки канала. Результаты. Оценивая риски ухудшения зрения в результате декомпрессии канала, мы установили, что сама декомпрессия без попыток отделения опухоли от нерва вызывает ухудшение зрения в 8,6 % случаев. Попытки отделения опухоли от зрительного нерва повышают риск ухудшения зрения до 16,7-26,9 % в зависимости от радикальности. Заключение. Небольшая частота осложнений (ятрогенного амавроза и назальной ликвореи) позволяет рекомендовать описанную методику как эффективное и безопасное дополнение к стандартным транскраниальным операциям по удалению менингиом хиазмально-селлярной области