Abstract
An urgent task of tribology is to study the wear mechanisms of various materials for the development of stable wear-resistant microstructures and optimal modes of their production. The ...purpose of this work is to assess the wear resistance of low-alloy steel with a submicrocrystalline ferritic matrix, reinforced with nano- and microspheres of cementite, as well as to reveal the features of its destruction by friction based on the analysis of friction surfaces. Steel nanostructuring was carried out using cold (at room temperature) equal-channel angular pressing and subsequent annealing. The process of steel wear in coarse-grained and nanosubmicron states has been studied at various stages of tribological loading under sliding friction conditions using optical and scanning electron microscopy, profilometry, and analysis of changes in the roughness parameters of friction surfaces. It is shown that the formation in steel of a heterogeneous structure “submicron ferrite matrix - nanoscale carbide phase” provided an increase in wear resistance by more than two times. The features of contact fracture are revealed, which determine the increase in the wear resistance of steel upon refining the structure and indicate significant differences in the nature of the metal tribological strength formation, depending on the level of dispersion of microstructural elements. The results obtained can be used in the development of technological processes for the formation of nanoscale structural components and improving the properties of traditional low-alloy steels.
The authors consider results of retrospective analysis of primary consultations of 2791 coal miners with occupational lumbosacral radiculopathy over 1976-2014 in Rostov regional occupational center. ...Findings are that 975 miners (34.9%) underwent examination of the disease connection with occupation, and occupational lumbosacral radiculopathy was diagnosed on primary consultation, but in 1816 miners (65.1%) recurrent lowerback pain and health-injury by occupational hazards were diagnosed. Recurrent lower back pain in miners was considered as a predictor of occupational lumbosacral radiculopathy. The authors suggested a way of prevention for occupational lumbosacral radiculopathy and comorbid conditions in miners during periodic medical examinations in occupational pathology center.
The study of structural and phase changes and processes of destruction of heat-resistant nickel alloys is necessary to solve urgent problems of improving the serviceability and reliability of parts ...of the hot path of gas turbine installations, including under severe temperature and power operating conditions in the North. The purpose of this work is to study the high-temperature degradation of metal and the nature of operational failures of parts of the hot path (heat insert, blades) of gas turbine units operating in an extremely cold climate. Using the methods of optical, scanning and transmission electron microscopy the morphological changes were revealed in the strengthening γ’-phase and other symptoms of instability in structural state of the alloys from which the failed parts had been made. The insufficient level of structural stability of alloys in non-stationary operating conditions of gas turbine installations in the North which sharply increase the load on the parts is revealed. The degradation of alloys was developed in the depletion of the solid solution by the intermetallide phase, the softening of intermetallide particles by internal defects, the development of intra-grain porosity, and the weakening of grain boundaries by precipitates and pores. The fracture of the heat insert (made of a deformable nickel alloy) was realized by the creep mechanism, the fracture of the working blades (made of a casting alloy) – by the thermal fatigue mechanism. A limited resource of the studied parts is caused by the insufficient level of service properties for the considered operating conditions as well as error modes of the gas turbines caused the overheating of parts. The improving of materials for gas turbine installations in the North requires the adapted optimization of alloys compositions and the development of technologies for manufacturing parts taking into account operating conditions.
The recombinant antigen obtained by cloning and expressing two IBV nucleocapsid protein fragments (143-414 aa, 281-414 aa) in
Escherichia coli was used for the detection of avian infectious ...bronchitis virus (IBV) specific antibodies in chicken sera by the indirect ELISA (rNpIBV-ELISA). As a result of testing 1524 serum samples the diagnostic sensitivity and specificity of rNpIBV-ELISA when comparing those of the routine whole IBV ELISA have been shown to be 93.81% and 87.36%, respectively. The agreement value was 91.5%.
Present status of muon diagnostics Yashin, I I; Ampilogov, N V; Astapov, I I ...
Journal of physics. Conference series,
01/2013, Volume:
409, Issue:
1
Journal Article
Peer reviewed
Open access
Muon diagnostics is a technique of remote monitoring of various dynamic processes in the heliosphere, the magnetosphere and the atmosphere of the Earth based on the analysis of spatial-angular and ...temporal variations of muon flux simultaneously detected from all directions of the upper hemisphere. The developed approaches to data analysis and results of the study of various terrestrial and extra-terrestrial processes detected by means of a wide aperture URAGAN muon hodoscope are discussed.
We have found that N-cholinolytic drug benzohexonium produces a hypolipidemic effect: it reduces dyslipoproteinemia, fatty infiltration of the liver, and risk of atherosclerotic lesions.
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