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The interaction of the T-cell receptor (TCR) with a peptide in the major histocompatibility complex (pMHC) plays a central role in the adaptive immunity of higher chordates. Due to the high specificity and sensitivity of this process, the immune system quickly recognizes and efficiently responds to the appearance of foreign and altered self-antigens. This is important for ensuring anti-infectious and antitumor immunity, in addition to maintaining self-tolerance. The most common parameter used for assessing the specificity of TCR-pMHC interaction is affinity. This thermodynamic characteristic is widely used not only in various theoretical aspects, but also in practice, for example, in the engineering of various T-cell products with a chimeric (CAR-T) or artificial (TCR-engineered T-cell) antigen receptor. However, increasing data reveal the fact that, in addition to the thermodynamic component, the specificity of antigen recognition is based on the kinetics and mechanics of the process, having even greater influence on the selectivity of the process and T lymphocyte activation than affinity. Therefore, the kinetic and mechanical aspects of antigen recognition should be taken into account when designing artificial antigen receptors, especially those that recognize antigens in the MHC complex. This review describes the current understanding of the nature of the TCR-pMHC interaction, in addition to the thermodynamic, kinetic, and mechanical principles underlying the specificity and high sensitivity of this interaction.

T2K is a long-baseline neutrino experiment that aims to investigate the CP violation in the neutrino sector. An upgrade of the ND280, which is one of the T2K near detectors, is in progress. The active target detector of the upgraded ND280 is a segmented highly granular plastic scintillation detector (SuperFGD) consisting of about two million scintillator cubes. About sixty thousand silicon photo-multipliers (SiPMs) coupled with wavelength shifting fibers are used for light readout. The fibers go through the scintillator cubes along the orthogonal three directions. We developed a novel system based on LEDs and notched light guide plates for in-situ calibration of the SuperFGD. The developed system can distribute LED light to SiPMs simultaneously with high uniformity and can be used for gain calibration and stability monitor of the signal readout. In addition, it can fit in the confined space of the SuperFGD due to its thin structure. In this paper, we report the design and the performance of the calibration system.

The authors review a coreset discovery problem and three main methods to solve it: geometric coreset estimation, coreset discovery using the genetic algorithm, and coreset discovery using neural networks. They analyze each of these methods and find the cases where they show the best results. The paper focuses on neural network-based approaches and their ability to solve the coreset discovery problem. The authors perform a comparative analysis of several neural network-based approaches, describe their pros and cons, and determine the further steps in solving the coreset discovery problem.

Genetic divergence and evolutionary shift of transitions and transversions ratio were analyzed based on examples of 60 sequences of the mtDNA control region of 27 species of mice (Murinae) of the Palearctic region. Representatives of Cricetidae and Arvicolidae were taken as outgroups. The constructed phenogram corresponds to the accepted phylogenetic scheme and is clustered according to population, semispecies, allospecies, species, genus and family levels of divergence. In the phyletic order there is a clearly defined evolutionary transition/transversion rate bias. Its distinction is an extremely fast and abrupt transition from dynamic to stable phase. The dynamic phase is a rapid decrease in the ti/tv rate ratio and refers to the population and semispecies divergence levels. The stable phase refers to the species level and higher divergence levels and is associated with reaching a state of genetic saturation in a situation of predominance of transversions. The extreme denotion of the evolutionary shift in the D-loop case can be explained by the removal of the selection pressure caused by restrictions in amino acid substitutions. This means that the causes of transition/transversion bias are purely biochemical mechanisms on DNA level. Simultaneously, the stability of the ti/tv ratio at species and higher levels amidst the further accumulation of the total number of nucleotide substitutions may indicate a fundamentally different nature of genetic processes at the intraspecies and interspecies levels of divergence.

A comparative analysis of the rates of molecular evolution, transition bias, and its evolutionary compensation was carried out on mitochondrial (D-loop, Cytb, COI, 12S RNA) and nuclear (IRBP, Fv) DNA markers in the Murinae subfamily. According to the levels of variability, the markers can be divided into three classes: (1) hypervariable (D-loop), (2) rapidly evolving (Cytb, COI), and (3) conservative (12S RNA, IRBP, Fv). The nature of nucleotide substitutions appears by the levels of variability. With the D-loop, there is a maximum initial bias, which is already partially compensated for during the early stages of speciation, and completely compensated at the stages of species divergence. The pronounced bias within the Cytb and COI genes is only partially compensated, moreover at the genus levels. The 12S RNA, IRBP, and Fv genes with a low level of transition bias do not show evolutionary compensation as such, and the decrease of the ts/tv index in the evolutionary lineage has a technical character and is a consequence of a relative decrease of the difference in the frequencies of transitions and transversions against the background of an absolute increase in the frequencies of substitutions. The positive relationship between the intensity of nucleotide substitutions, the level of transition bias, and the rates of its evolutionary compensation proves that these phenomena have the same primary basis.

The authors propose the technological algorithm to obtain the required quality characteristics of beneficiation feed based on the estimate of useful mineral distribution and amount of gangue in a preset volume. The target useful component content is implemented by combining separation and blending of crushed ore less than 100 mm in size. It is shown that this approach to the feed quality ensures the standard content of P 2 O 5  in the feed at the level of 12.1–12.3% with dumping not less than 29% of gangue -100+20 mm in size with the content of P 2 O 5  under 1.9%. It is proved that the proposed technology for the control of quality characteristics of low-grade apatite-bearing ore has a beneficial effect on the environment in mining and processing areas.

AbstractWater has a complex structure and contains impurities, the chemical composition of which is determined not only by the natural content, but also by the conditions of processing and preparation for consumption. It is known that water can crystallize into ice at low temperatures and form crystals and snowflakes with different patterns. But such crystals are not stable at higher temperatures because of melting. Therefore, it is quite difficult to study crystallized water without special equipment. With the aim of elucidating the possibility of visual morphological integral registration of the crystallographic pattern, three specimens of drinking water were crystallized with addition of a crystal-forming substance. This method is based on changing the crystal formation process after addition of another substance or a solution to the crystal-forming substance. Copper dichloride CuCl2⋅2H2O can serve as such a sensitive crystal-forming substance. This method is called thesiography. Drinking water samples with different chemical compositions—in particular, water from a well for domestic use, water supplied centrally for human consumption in accordance with DSTU 7525 : 2014 (State Standard of Ukraine), and natural mineral table water not subjected to technical treatment—are studied. The crystallographic patterns are visually inspected for the morphology after their formation with use of temperature contrasting for better visualization. It is found that a crystallographic portrait of water can be obtained by crystallizing water with a crystal-forming substance. The constituent components of water are embedded in the crystal lattice of the crystal-forming substance, i.e., copper dichloride CuCl2⋅2H2O. Therefore, thesiography of water is a promising method to obtain portrayal characteristics of various drinking water samples and can be used to assess water quality. Different water samples have different crystallographic patterns due to the different chemical compositions.

This paper presents the results of the study of the composite based on magnesium hydride with the addition of nanosized nickel powder, obtained by the method of an electric explosion of wires. The obtained MgH2-EEWNi (20 wt.%) composite with the core-shell configuration demonstrated the development of a defect structure, which makes it possible to significantly reduce the hydrogen desorption temperature from 418 °C for pure magnesium hydride to 229 °C for hydride with the addition of nickel powder. In situ studies of the evolution of the defect structure using positron annihilation methods and diffraction methods made it possible to draw conclusions about the influence of the Mg2NiH0.3 and Mg2NiH4 phases on the sorption and desorption properties of the composite. The results obtained in this work can be used in the field of hydrogen energy in mobile or stationary hydrogen storage systems.

ObjectiveTo evaluate safety and postoperative visual outcomes of low-energy femtosecond laser-assisted (FLA) anterior capsulotomy in paediatric cataract surgery.Methods and analysisWe report a retrospective single-centre consecutive case series of 51 eyes of 33 paediatric cataract patients with a mean age of 3.22 years (range: 2 months to 13 years) who underwent cataract surgery with FLA anterior capsulotomy, using FEMTO LDV Z8 femtosecond laser (Ziemer Ophthalmic Systems). Anterior laser capsulotomy, phacoaspiration and intraocular lens implantation were performed in all eyes. Both intraoperative and long-term postoperative complications, along with long-term monocular corrected distance visual acuity (CDVA), were assessed during average follow-up period of 32.96 months (range: 13–69 months).ResultsIn 48 out of 51 eyes, a well-sized and well-located anterior capsulotomy was achieved without intraoperative complications. Anterior capsule tears occurred in three eyes; however, they did not extend posteriorly and the intraocular lens were placed in the bags without any further complications. Posterior capsular opacification developed in 45.10% of eyes (23 out of 51) and was subsequently treated with neodymium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy. Mean CDVA at final follow-up was 20/40 (range: 20/63 to 20/32) in unilateral cases younger than 12 months, 20/40 (range: 20/1000 to 20/25) in unilateral cases older than 12 months, 20/66 (range: 20/400 to 20/32) in bilateral cases younger than 12 months and 20/40 (range: 20/200 to 20/20) in bilateral cases older than 12 months.ConclusionsPaediatric cataract surgery with low-energy FLA anterior capsulotomy is a procedure with long-term safety, resulting in significant improvement in CDVA.

AbstractThe accuracy of estimating the relative abundance of generations of fish species under conditions of incomplete initial information is analyzed. Using the example of bream from the Kuibyshev Reservoir, it is shown that, if the information on the age structure is lost for 1 to 8 years, the error in estimating the abundance of generations averages from 5 to 15%. This makes it possible to apply this modification of the method of loss from fishing to estimate the abundance of fish generations in the current conditions. This method of estimating the number of generations may be useful in the analysis not only of fish, but also of other aquatic organisms.