The mechanism of plastic deformation of a MAX phase based on Ti–Al–C elements is investigated in the temperature range 1000–1200 °C. It is shown that at temperatures about 1000 °C the determining ...mass transport mechanism is the grain-boundary creep. Upon reaching a temperature of above 1100 °C the plastic deformation of the material occurs with the participation of a Ti–Al-based liquid phase, that appears as a thin (
≈
10
nm
) layer at the grain boundaries of TiC. This deformation mechanism is characterized by a higher rate of plastic deformation as compared to that in a solid phase, that is in the absence of liquid interlayers.
The disturbed metabolism of vitamins B1 or B6, which are essential for neurotransmitters homeostasis, may cause seizures. Our study aims at revealing therapeutic potential of vitamins B1 and B6 by ...estimating the short- and long-term effects of their combined administration with the seizure inductor pentylenetetrazole (PTZ). The PTZ dose dependence of a seizure and its parameters according to modified Racine’s scale, along with delayed physiological and biochemical consequences the next day after the seizure are assessed regarding sexual dimorphism in epilepsy. PTZ sensitivity is stronger in the female than the male rats. The next day after a seizure, sex differences in behavior and brain biochemistry arise. The induced sex differences in anxiety and locomotor activity correspond to the disappearance of sex differences in the brain aspartate and alanine, with appearance of those in glutamate and glutamine. PTZ decreases the brain malate dehydrogenase activity and urea in the males and the phenylalanine in the females. The administration of vitamins B1 and B6 24 h before PTZ delays a seizure in female rats only. This desensitization is not observed at short intervals (0.5–2 h) between the administration of the vitamins and PTZ. With the increasing interval, the pyridoxal kinase (PLK) activity in the female brain decreases, suggesting that the PLK downregulation by vitamins contributes to the desensitization. The delayed effects of vitamins and/or PTZ are mostly sex-specific and interacting. Our findings on the sex differences in sensitivity to epileptogenic factors, action of vitamins B1/B6 and associated biochemical events have medical implications.
Unlike the
OGDH
-encoded 2-oxoglutarate dehydrogenase (OGDH), which is an essential enzyme present in all animal tissues, expression of the
DHTKD1
-encoded isoenzyme, 2-oxoadipate dehydrogenase ...(OADH), depends on a number of factors, and mutant
DHTKD1
phenotypes are rarely manifested. Physiological significance of OADH is also obscured by the fact that both isoenzymes transform 2-oxoglutarate and 2-oxoadipate. By analogy with other members of the 2-oxo acid dehydrogenases family, OADH is assumed to be a component of the multienzyme complex that catalyzes oxidative decarboxylation of 2-oxoadipate. This study aims at molecular characterization of OADH from animal tissues. Phylogenetic analysis of 2-oxo acid dehydrogenases reveals OADH only in animals and
Dictyostelium discoideum
slime mold, within a common branch with bacterial OGDH. Examination of partially purified animal OADH by immunoblotting and mass spectrometry identifies two OADH isoforms with molecular weights of about 130 and 70 kDa. These isoforms are not observed upon the expression of human
DHTKD1
protein in either bacterial or yeast system, where the synthesized OADH is of expected molecular weight (about 100 kDa). Thus, the OADH isoforms present in animal tissues, may result from the animal-specific regulation of the
DHTKD1
expression and/or posttranslational modifications of the encoded protein. Mapping of the peptides identified in the OADH preparations, onto the protein structure suggests that the 70-kDa isoform is truncated at the N-terminus, but retains the active site. Since the N-terminal domain of OGDH is required for the formation of the multienzyme complex, it is possible that the 70-kDa isoform catalyzes non-oxidative transformation of dicarboxylic 2-oxo acids that does not require the multienzyme structure. In this case, the ratio of the OADH isoforms in animal tissues may correspond to the ratio between the oxidative and non-oxidative decarboxylation of 2-oxoadipate.
The authors developed new high-performance analytical methods for modeling diffused gas concentration fields in intra- and interparticle spaces in heterogeneous n-component nanoporous media using the ...Heaviside operational method and Cauchy influence matrices for heterogeneous adsorption boundary-value problems for systems of partial differential equations with feedback.
The relationship between a variety's genotype, environmental conditions and phytopathogenic load are the key factors contributing to high yields that should be taken into account in selecting donors ...for resistance and high manifestation of valuable traits. The study of leaf rust resistance in 49 common wheat varieties was carried out in the field against the natural pathogen background and under laboratory conditions using single-pustule isolates with virulence to Lr9 and Lr24. It has been shown that the varieties carrying alien genes Lr6Agi2 (Tulaikovskaya 10) and Lr6Agi1 (Voevoda) were resistant to leaf rust infection both in the field and in the laboratory. Varieties KWS Buran, KWS Akvilon, KW 240-3-13, and Etyud producing crop yields from 417 to 514 g/m2 comparable to the best standard variety Sibirskaya 17 can be reasonably used as Lr24 resistance gene donors under West Siberian conditions. Omskaya 44 variety showing crop yield of 440g/m2 can be used as a donor for Lr19 and partially effective Lr26. Varieties Tuleevskaya and Altayskaya 110 with Lr9 in their genomes are recommended for the development of resistance gene-pyramided genotypes. The highest protein and gluten contents were observed in the CS2A/2M sample, while KWS Buran, Altayskaya 110, Volgouralskaya, and KWS Akvilon showed the lowest values. Varieties CS2A/2M, Tulaikovskaya 10, Pavon, and Tuleevskaya were ranked the highest in micro- (Cu, Mn, Zn, Fe) and macronutrient (Ca, Mg, K) contents among the common wheat samples from the collection, while the lowest values for most elements were observed in KWS Buran, Novosibirskaya 15, and Volgouralskaya. Winter varieties demonstrating leaf rust resistance against the infectious background typically carry adult plant resistance genes (Lr34, Lr12, and Lr13), particularly combined with the juvenile Lr26 gene. The presence of Lr41 in a winter type line (KS 93 U 62) allowed it to maintain resistance against a leaf rust pathogen clone kLr24, despite the presence of Lr24 in the genotype. Varieties Doka and Cheshskaya 17 may act as donors of resistance genes Lr26 + Lr34 and Lr9 + Lr12 + Lr13 + Lr34, as well as sources of dwarfing without losses in winter hardiness and yield under West Siberian conditions.
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.
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