Development of a Flow-Measuring Hydropneumatic Bench for Testing Pipeline Valves

Pipe fittings are an important element of any pipeline network, ensuring stable and safe operation by regulating the flow of the working medium. To control the performance of pipeline valves, it is necessary to conduct various tests, the main ones of which are hydraulic and pneumatic. It is important to expand testing capabilities and reduce time costs. The purpose of this work is to combine hydraulic and pneumatic tests into one test complex, which will reduce the time of the test complex due to the absence of the need for reinstallation and reconfiguration. The subject of the study is the determination of the design, technical, and operational characteristics of such a stand, as well as the simulation of operating conditions to confirm its operability. During the development, methods of solid and surface modeling, the finite element method, and analytical calculation methods were used. The results of the stand design are presented, and the features of the process of its development are described, including the analysis of the stress-strain state and the analysis of reliability and durability indicators. The obtained values of the distribution of equivalent stresses, deformations, and displacements of the structure elements do not exceed the maximum allowable values and do not lead to destruction. The analysis shows that the developed stand has improved capabilities compared to those previously used. Doi: 10.28991/CEJ-2023-09-01-013 Full Text: PD

Transoral-transpharyngeal CO2 laser en bloc excision of voluminous left recurrent laryngeal nerve schwannoma: Case report and review of the literature

Recurrent nerve laryngeal schwannoma is a rare benign tumor that, in expert hands, can be treated by transoral CO2 laser surgery

Multi-omics phenotyping of the gut-liver axis reveals metabolic perturbations from a low-dose pesticide mixture in rats.

Health effects of pesticides are not always accurately detected using the current battery of regulatory toxicity tests. We compared standard histopathology and serum biochemistry measures and multi-omics analyses in a subchronic toxicity test of a mixture of six pesticides frequently detected in foodstuffs (azoxystrobin, boscalid, chlorpyrifos, glyphosate, imidacloprid and thiabendazole) in Sprague-Dawley rats. Analysis of water and feed consumption, body weight, histopathology and serum biochemistry showed little effect. Contrastingly, serum and caecum metabolomics revealed that nicotinamide and tryptophan metabolism were affected, which suggested activation of an oxidative stress response. This was not reflected by gut microbial community composition changes evaluated by shotgun metagenomics. Transcriptomics of the liver showed that 257 genes had their expression changed. Gene functions affected included the regulation of response to steroid hormones and the activation of stress response pathways. Genome-wide DNA methylation analysis of the same liver samples showed that 4,255 CpG sites were differentially methylated. Overall, we demonstrated that in-depth molecular profiling in laboratory animals exposed to low concentrations of pesticides allows the detection of metabolic perturbations that would remain undetected by standard regulatory biochemical measures and which could thus improve the predictability of health risks from exposure to chemical pollutants

PROBLEM OF NUMERICAL ANALYSIS OF DEFORMATION OF BINDED REINFORCED CONCRETE ELEMENTS

In 1938 standards were adopted in which the method of limiting equilibrium, developed by prof. А.А. Gvozdev and V.I. Murashev, was recommended for the calculation of reinforced concrete structures. From the very beginning, the proposed method caused a sharp discussion in the scientific community, since it contained number of contradictions. Most of the contradictions in the theory of A.A. Gvozdev became part of modern Russian standards. Until now the method of limiting equilibrium remains the main method for calculating reinforced concrete structures for strength. In recent years, a discussion has been developed on the transition to the deformation model of reinforced concrete resistance used by the European codes. In view of this, the updated version of domestic regulations allows the calculation of reinforced concrete structures using a nonlinear deformation model. However, there is a limited number of studies confirming the consistency of the proposed deformation model. In this regard we performed a series of calculations of rigidity of hinged supported on the basis of the theoretical and deformation models of the Russian standards. The calculation was carried out by the finite element method using the model of nonlinear deformation of concrete

Lower Bound on the Magnetic Field Strength of a Magnetar from Analysis of SGR Giant Flares

Based on the magnetar model, we have studied in detail the processes of neutrino cooling of an electron--positron plasma generating an SGR giant flare and the influence of the magnetar magnetic field on these processes. Electron--positron pair annihilation and synchrotron neutrino emission are shown to make a dominant contribution to the neutrino emissivity of such a plasma. We have calculated the neutrino energy losses from a plasma-filled region at the long tail stage of the SGR 0526--66, SGR 1806--20, and SGR 1900+14 giant flares. This plasma can emit the energy observed in an SGR giant flare only in the presence of a strong magnetic field suppressing its neutrino energy losses. We have obtained a lower bound on the magnetic field strength and showed this value to be higher than the upper limit following from an estimate of the magnetic dipole losses for the magnetars being analyzed in a wide range of magnetar model parameters. Thus, it is problematic to explain the observed energy release at the long tail stage of an SGR giant flare in terms of the magnetar model.Comment: 18 pages, 5 figure

Gender-Concealed Concepts in Conceptual Space Languages of Dagestan

The present paper analyzes definitions of the languages of Dagestan with the scope of notions of “the language of men/the language of women”. Many meaningful units of gender are updated within the framework of this classification. The material with a multitude of gender units was dispersed in the conceptual space of Russian and Dagestan languages; however, it was restored by the representation of stereotypes “noun ± adjective”. This allows justifiably to streamline the conceptual space of languages of Dagestan with many interpretations of the surrounding reality. The preference given to the aforementioned classification is because the connotative aspect of nominative units allows for the limination of overlays, i.e. cases of reference of the same interpretations to different terminological headings simultaneously