Microstructure evolution of a ti/tib metal-matrix composite during high-temperature deformation

A Ti/TiB metal-matrix composite (MMC) was produced by spark plasma sintering using a Ti-10wt.%TiB2 powder mixture at 850°C under a load of 40 MPa for 15 min. The microstructure evolution and mechanical behavior of the Ti/TiB composite during uniaxial compression at the temperature range 500 - 1050°С was studie

Microstructure evolution of commercial-purity titanium during cryorolling

Electron backscatter diffraction and transmission electron microscopy have been used to analyze the microstructural evolution of titanium during rolling at a cryogenic temperature (T = –196°C). It has been found that intensive twinning at the cryogenic deformation temperature accelerates the kinetics of micro structure refinement. The quantitative analysis of microstructure evolution in titanium upon cryorolling has shown that structure evolution is mainly related to mechanical twinning in the initial stages cryorolling is discusse

Effect of second phase particles on mechanical properties and grain growth in a CoCrFeMnNi high entropy alloy

Effect of annealing of a cold-worked CoCrFeMnNi alloy at temperatures of 500-900°C for 1-50 h on the structure and mechanical properties was studied in the present wor

Effect of plastic deformation on the structure and properties of the Ti/TiB composite produced by spark plasma sintering

A Ti/17 vol % TiB composite material is produced by spark plasma sintering of a mixture of titanium and 10 wt % TiB2 powders at a temperature of 1000°C. Multiaxial isothermal forging is performed at t = 850°C to enhance the mechanical properties of the composit

Evolution of microstructure and mechanical properties of Tibased metal-matrix composites during high-pressure torsion

The microstructure and microhardness evolution of a Ti/TiB and Ti15(wt.%) Mo/TiB metal-matrix composites (MMC) during high-pressure torsion (HPT) at 400 °C was studie

Microstructure and texture evolution of a high manganese TWIP steel during cryo-rolling

The influence of rolling at 77 K and 293 K to a true strain of 2.66 on the microstructure and texture evolution and mechanical behavior of a TWIP Fe-0.3C-23Mn-1.5Al steel was quantified. The microstructure evolution at both temperatures of deformation was associated with an increase in the dislocation density and extensive twinning, following by the development of a cell structure and shear band

Psychological and Physiological Health of Schoolchildren in the Modern Educational Environment

Благодарности: научному руководителю Иванову Виктору Михайловичу, доктору сельскохозяйственных наук, профессору кафедры психофизиологии и безопасности жизнедеятельности за методическую помощь в проведении исследований, а также написании и оформлении работы.Acknowledgments: scientific supervisor Viktor Mikhailovich Ivanov, Doctor of Agricultural Sciences, Professor at the Department of Psychophysiology and Life Safety for the methodical assistance in conducting research, as well as writing and designing the work.В статье приводятся данные об ухудшении здоровья школьников в России, поэтому изучение их психологических и физиологических показателей является актуальной задачей. Нами были разработаны мероприятия, которые позволили минимизировать воздействия неблагоприятных факторов на организм учащихся.Тhe article provides data on the deterioration of schoolchildren’s health in Russia, so the study of their psychological and physiological indicators is an urgent task. We have developed measures to minimize the impact of adverse factors on the body of students

Microstructure evolution during warm working of Ti-5Al-5Mo-5V-1Cr-1Fe at 600 and 800°C

Microstructure evolution during compression to the true height strain 0.29, 0.69, or 1.2 at 600 and 800. °C of the Β-rich titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) with an initial lamellar microstructure was established using scanning and transmission electron microscopy. It was found that microstructure evolution at both temperatures was controlled primarily by substructure evolution within the Β phase. At 800. °C, extensive recovery within the Β phase resulted in the formation of a stable structure comprising subgrains ~1.5. μm in diameter. During deformation at this temperature, lamellae of the α phase fragmented via a boundary-grooving mechanism. Due to the sluggish diffusion kinetics, however, spheroidization at 800. °C was incomplete. At the lower processing temperature, recovery processes within the Β phase were much slower, leading to greater refinement of the Β matrix. The decomposition of the metastable Β phase during warm working, gave rise to very fine α-lath precipitates, which resulted in the formation of an ultrafine microstructure with a grain size of 0.5. μm. © 2012 Elsevier B.V

Kinetics of recrystallization and grain growth in an ultra-fine grained CoCrFeNiMn-type high-entropy alloy

A novel high entropy alloy based on the CoCrFeMnNi system with substantial amounts of Al and C was studied. After cold rolling and annealing at 973-1273 K a duplex ultrafine grained structure composed of the recrystallized fcc grains and M23C6 and B2 particles was produced. Analysis of the coarsening behavior of grains and particles growth suggested that kinetics of both was controlled by volume diffusion. The apparent activation energy of structure coarsening during recrystallization was evaluate

The ultradian rhythm of glucocorticoid secretion and the time course of target gene regulation

Glucocorticoid hormones (cortisol in humans and corticosterone in rodents) are secreted in discrete pulses during a day with a periodicityof approximately 1 h (ultradian rhythm), and this pattern is also maintained in plasma and extracellular fluid. However, the vast majority of studies on gene regulation by glucocorticoids typically assess gene responses regardless the ultradian rhythm. These experiments are usually performed using long-term stimulation with synthetic hormones (dexamethasone and triamcinolone), which form much more stable complexes with glucocorticoid receptor (GR) then natural hormones. This review summarizes the current scarce information, obtained in experiments mimicking the ultradian mode of natural hormone secretion in cultured cells and in animal models. The results of these experiments clearly demonstrate that ultradian stimulation by natural hormones induces rapid GR exchange with glucocorticoid response elements and leads to cyclic GR mediated transcriptional regulation (gene pulsing) at the level of nascent RNA. In contrast, synthetic glucocorticoids, having much higher receptor affinity, fail to disengage from nuclear receptors with sufficient speed to support the ultradian cycles, thereby uncoupling extracellular hormone fluctuations from appropriate receptor function at response elements. This alters RNA accumulation profiles dramatically. These findings suggest potentially important consequences of ultradian secretion. The transcriptional program induced by hormone pulses differs significantly from that generated by constant hormone treatment. Thus, treatment with synthetic glucocorticoids may not provide an accurate assessment of physiological hormone action