The active channels in AlGaN/GaN‐based heterostructures are studied under different applied electrical fields to identify the Joule heating factors affecting the temperature values in the channels. ...The temperature in active channels of two different lengths (30 and 180 µm) is characterized using optical methods, and electrical methods are used as a reference. The technique of optical thermometry is based on the data of micro‐photoluminescence and micro‐Raman experiments. The electrical method is based on the measurements of current–voltage characteristics for comparison. It is shown that photoluminescence‐ and electrical‐based temperature values demonstrate similar behavior and good correlation. The Raman‐based method, exploiting the temperature dependence of the frequency position of E2high vibrational band in GaN, shows a significant deviation compared with electrical‐ and luminescence‐based methods. This deviation is shown to be related to the residual mechanical strain in the layered structure and the formation of hot phonons. The influence of hot phonons and mechanical strain effects increases at high electrical load (>5 kV cm−1) and at high temperatures (>400 °C), respectively.
Temperature rise studies in the active AlGaN/GaN channels using several methods reveal the considerable contribution of two important effects: residual mechanical strain and the formation of hot phonons. The influence of hot phonons and mechanical strain effects increases at high electrical load (>5 kV cm−1) and at high temperatures (>400 °C), respectively.
A promising direction for improving the balance of the diet of livestock and poultry by trace element composition is the enrichment with ultrafine particles of scarce trace elements. At the same ...time, it is important that they are evenly distributed throughout the volume of the feed mixture. The purpose of this study is to increase the uniformity of the distribution of ultrafine particles in feed mixture by developing special equipment and improving the technological process. The use of new technologies for preparing feed mixtures based on the control of process parameters makes it possible to obtain a product with specified functional parameters and preserved nutritional properties. Analysis of theoretical studies of the process of dosing and mixing ultrafine particles has shown that the best variant of their motion in the mixture flow is laminar motion. The designed processing line provides for the separate supply of premixed feed mixture and ultraparticles to the vibrating mixer. The efficiency of the mixing process in a vibrating mixer was assessed using three sections of a feed mixture with ultraparticles of iron, zinc, cobalt, and molybdenum powders. The optimal working parameters are achieved under the following conditions: the angular velocity of the vibrating mixer is 3–7 rad/s, the oscillation frequency is 9–37 Hz, the vibration mixing time is 113–333 s, and the time for opening the controlled dispenser (feeding ultrafine particles into the vibrating mixer) is 5–15 s. When using a controlled ultraparticle dispenser and a spherical impeller, the particles were distributed more evenly in the feed. The lowest effect on the value of this indicator in the three sections of the feed mixture has been recorded for zinc (up to 2.7%), followed by iron powders (up to 3.6%) and molybdenum powders (up to 9.5%). The developed equipment had the greatest effect on the uniformity of cobalt distribution (up to 20.5%). At the same time, the deviation from the norm (0.5 mg/kg) did not exceed 2%; i.e., the value of the qualitative indicator of uniformity of the distribution was 98%.
The study of physical processes associated with acoustic phonons in nitride-based nanosystems is of great importance for the effective operation of modern nanoscale devices. In this paper, a ...consistent theory of acoustic phonons arising in multilayer nitride-based semiconductor resonant tunneling structures, that can function as a separate cascade of a quantum cascade laser or detector is proposed. Using the physical and geometric parameters of a typical nanostructure, the spectrum of various types of acoustic phonons and the corresponding normalized components of the elastic displacement vector are calculated. It has been established that the spectrum of acoustic phonons of a multilayer nanostructure consists of two groups of the shear phonons dependencies and three groups of dependencies for a mixed spectrum of flexural and dilatational phonons. The dependencies of the acoustic phonons spectrum of the nanostructure and the components of the elastic displacement vector on its geometric parameters are studied. It has been established that for the components of the displacement vector u2 for shear phonons have a decrease in the absolute values of their maxima with increasing of energy level number. The components u1 and u3 of flexural and dilatational phonons behave respectively as symmetric and antisymmetric functions relatively the center of an separate selected layer of the nanostructure. The proposed theory can be further applied to study the interaction of electrons with acoustic phonons in multilayer resonant tunneling structures.
Present-day wheat breeding for immunity exploits extensively closely related species from the family Triticeae as gene donors. The 2NS/2AS translocation has been introduced into the genome of the ...cultivated cereal Triticum aestivum from the wild relative T. ventricosum. It contains the Lr37, Yr17, and Sr38 genes, which support seedling resistance to the pathogens Puccinia triticina Eriks., P. striiformis West. f. sp. tritici, and P. graminis Pers. f. sp. tritici Eriks. & E. Henn, which cause brown, yellow, and stem rust of wheat, respectively. This translocation is present in the varieties Trident, Madsen, and Rendezvous grown worldwide and in the Russian varieties Morozko, Svarog, Graf, Marquis, and Homer bred in southern regions. However, the Sr38 gene has not yet been introduced into commercial varieties in West Siberia; thus, it remains of practical importance for breeding in areas where populations of P. graminis f. sp. tritici are represented by avirulent clones. The main goal of this work was to analyze the frequency of clones (a)virulent to the Sr38 gene in an extended West Siberian collection of stem rust agent isolates. In 2019-2020, 139 single pustule isolates of P. graminis f. sp. tritici were obtained on seedlings of the standard susceptible cultivar Khakasskaya in an environmentally controlled laboratory (Institute of Cytology and Genetics SB RAS) from samples of urediniospores collected on commercial and experimental bread wheat f ields in the Novosibirsk, Omsk, Altai, and Krasnoyarsk regions. By inoculating test wheat genotypes carrying Sr38 (VPM1 and Trident), variations in the purity of (a)virulent clones were detected in geographical samples of P. graminis f. sp. tritici. In general, clones avirulent to Sr38 constitute 60 % of the West Siberian fungus population, whereas not a single virulent isolate was detected in the Krasnoyarsk collection. The Russian breeding material was screened for sources of the stem rust resistance gene by using molecular markers specif ic to the 2NS/2AS translocation. A collection of hybrid lines and varieties of bread spring wheat adapted to West Siberia (Omsk SAU) was analyzed to identify accessions promising for the region. The presence of the gene was postulated by genotyping with specif ic primers (VENTRIUP-LN2) and phytopathological tests with avirulent clones of the fungus. Dominant Sr38 alleles were identif ied in Lutescens 12-18, Lutescens 81-17, Lutescens 66-16, Erythrospermum 79/07, 9-31, and 8-26. On the grounds of the composition of the West Siberian P. graminis f. sp. tritici population, the Sr38 gene can be considered a candidate for pyramiding genotypes promising for the Novosibirsk, Altai, and Krasnoyarsk regions.
In vitro
and in cell cultures, succinyl phosphonate (SP) and adipoyl phosphonate (AP) selectively target dehydrogenases of 2-oxoglutarate (OGDH, encoded by
OGDH/OGDHL
) and 2-oxoadipate (OADH, ...encoded by
DHTKD1
), respectively. To assess the selectivity in animals, the effects of SP, AP, and their membrane-penetrating triethyl esters (TESP and TEAP) on the rat brain metabolism and animal physiology are compared. Opposite effects of the OGDH and OADH inhibitors on activities of OGDH, malate dehydrogenase, glutamine synthetase, and levels of glutamate, lysine, citrulline, and carnosine are shown to result in distinct physiological responses. ECG is changed by AP/TEAP, whereas anxiety is increased by SP/TESP. The potential role of the ester moiety in the uncharged precursors of the 2-oxo acid dehydrogenase inhibitors is estimated. TMAP is shown to be less efficient than TEAP, in agreement with lower lipophilicity of TMAP
vs
. TEAP. Non-monotonous metabolic and physiological impacts of increasing OADH inhibition are revealed. Compared to the non-treated animals, strong inhibition of OADH decreases levels of tryptophan and beta-aminoisobutyrate and activities of malate dehydrogenase and pyruvate dehydrogenase, increasing the R–R interval of ECG. Thus, both metabolic and physiological actions of the OADH-directed inhibitors AP/TEAP are different from those of the OGDH-directed inhibitors SP/TESP, with the ethyl ester being more efficient than methyl ester.
Bisurea calix4arenes 1 and 2 possessing L-amino acid moieties at the lower rim were synthesized by reaction of the methyl esters of glycine, L-alanine, or L-isoleucine with the appropriate isocyanate ...(12 or 13), obtained with a safe and efficient Curtius rearrangement from the corresponding carboxylic acid derivatives. The conformational properties of the ligands 1 and 2 were investigated by means of a combined NMR and molecular modeling study which evidences that they are deeply influenced by strong intramolecular H-bonds between the urea NH groups and the vicinal phenolic oxygen atoms or the opposite urea C=O group. Complexation studies performed by ESI-MS and NMR spectroscopy in acetone solution show that the binding ability of these bisurea hosts decreases by increasing the side chain size of the amino acid. Host 2b has a remarkable binding ability for the N-acetyl-D-phenylalaninate anion with an interesting enantioselectivity (KDass/KLass=4.14), which is explained on the basis of a three-point interaction mode of binding.
The glutarylation of lysine residues in proteins attracts attention as a possible mechanism of metabolic regulation, perturbed in pathologies. The visualization of protein glutarylation by antibodies ...specific to ε-glutaryl-lysine residues may be particularly useful to reveal pathogenic mutations in the relevant enzymes. We purified such antibodies from the rabbit antiserum, obtained after sequential immunization with two artificially glutarylated proteins, using affinity chromatography on ε-glutaryl-lysine-containing sorbents. Employing these anti(ε-glutaryl-lysine)-antibodies for the immunoblotting analysis of rat tissues and mitochondria has demonstrated the sample-specific patterns of protein glutarylation. The study of the protein glutarylation in rat tissue homogenates revealed a time-dependent fragmentation of glutarylated proteins in these preparations. The process may complicate the investigation of potential changes in the acylation level of specific protein bands when studying time-dependent effects of the acylation regulators. In the rat brain, the protein glutarylation, succinylation and acetylation patterns obtained upon the immunoblotting of the same sample with the corresponding antibodies are shown to differ. Specific combinations of molecular masses of major protein bands in the different acylation patterns confirm the selectivity of the anti(ε-glutaryl-lysine)-antibodies obtained in this work. Hence, our affinity-purified anti(ε-glutaryllysine)-antibodies provide an effective tool to characterize protein glutarylation, revealing its specific pattern, compared to acetylation and succinylation, in complex protein mixtures.
High-performance methods and computer technologies for modeling of non-isothermal gas adsorption in nanoporous cyber-feedback systems based on the Heaviside operating method and Landau’s ...linearization approach to Langmuir’s nonlinear adsorption equilibrium using decomposition in a convergent series at the temperature transition point with subsequent efficient parallelization of the model over a small parameter are developed. The results of numerical experiments based on high-speed parallel computations on multicore computers are presented.
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