Ab initio-based prediction and TEM study of silicide precipitation in titanium

In this work we applied our recently developed thermodynamic model to predict the structure of Ti-Si precipitates in α-Ti matrix of the Ti-Si alloy with total Si concentration of 0.7 wt.%. We considered all prominent Ti-Si phases such as Ti₃Si; Ti₅Si₃; Ti₅Si₄; TiSi and two TiSi₂ phases and discovered that formation of the Ti₅Si₃ phase is more favorable than that of the Ti₃Si in contradiction with the known phase diagrams. Theoretical result was confirmed by experimental investigation of microstructure and phase composition of the model Ti-0.7Si alloy annealed at 873 K for 10 h. Indeed, the only observed phase has hexagonal Ti₅Si₃ structure. To ensure the completeness of the results we calculated ab initio elastic constants for all considered Ti-Si phase

Vortex Interferometric Microscopy with Laguerre-Gaussian Beams

In the present research, we discuss the results of analysis of coherent light beams carrying an optical vortex and propagating through the isotropic medium with a complex surface microrelief and its application to super resolution microscopy. It was shown, that phase analysis of singular beam with single charged centered optical vortex allow to retrieve information about sample surface relief. High spatial resolution caused by vortex helical phase sensitivity to disturbances in wave front after reflection or spreading through studying sample, which can be optically transparent or have a reflecting surface. This method applicable for non-destructive testing of live cells and biological tissues in real-time regime with exceeding optical diffraction limit. Vertical resolution of a microscope based on the phase singularity of Laguerre-Gaussian beams of low order can be achieved down to 5,27 nm for helium-neon laser source for optically transparent and reflecting surfaces. Keywords: optical vortex, phase, microscopy, singularit

Evolutionary search for new compounds in the Ti-Si system

In this work, the results of the evolutionary variable-composition search for binary compounds in the Ti-Si system are presented. The evolutionary algorithm did not find any new stable structures of silicides at 0 K and 0 GPa. On the other hand, many low-energy metastable and unstable structures are predicted. The 33 predicted and 10 known from literature but previously unstudied structures of compounds with low formation energies with respect to the ground-state line are analyzed. The mechanical properties, electronic band structures, densities of states, and temperature dependencies of thermodynamic stability of 17 dynamically stable previously unstudied structures are calculate

Sequence Stratigraphy and Onlap History of the Donets Basin, Ukraine: Insight into Carboniferous Icehouse Dynamics

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap-offlap history for a 33-my interval of the Carboniferous using the U-Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes in glacial extent, and climate. Integrated subsurface and outcrop data permit meter-scale correlation of 242 biostratigraphically constrained limestones and coals, and in turn individual cyclothems, across ~250 km of the Donets Basin. Rapid uniform subsidence and basinwide continuity of marker beds indicate Pennsylvanian deposition under relatively stable tectonic conditions. Three scales of sequences (avg. durations of ~140 ky, ~480 ky and 1.6 my) are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages. The hierarchy of sequences and the geographic and stratigraphic positions of shifts in base-level sensitive facies across the Donets ramp permit the construction of an onlap-offlap history at a sub-400 ky scale. Major sea-level lowstands occur across the mid-Carboniferous boundary and during the early Moscovian. These lowstands coincide with glacial maxima inferred from high-latitude glacigenic deposits. The middle to late Pennsylvanian is characterized by a stepwise onlap, culminating in an earliest Gzhelian highstand, suggesting contraction of Carboniferous ice sheets prior to the initiation of Early Permian glaciation. The stratigraphic position of climate sensitive facies within individual Donets cyclothems indicates a turnover from seasonal sub-humid or semi-arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation. Comparison of the stratigraphic and aerial distribution of coals and evaporites in the Donets Basin with the onlap-offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate (~0.8 to 1.6 my) and long (106 yr) time-scales. Taken together, the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high-latitude ice sheet behavior and low-latitude atmospheric dynamics

RESEARCH OF PARAMETERS OF THE RESONANCE MEASURING CONVERTER WITH CUTOFF PART

In this paper the design and a theoretical study of resonator measuring converter with cutoff part are proposed

NANOCOMPONENT BACTERICIDE MATERIAL

In this article bactericidal material was proposed. A key features of this material are the ability to inhibit reproduction of bacteria and not to make a change in the chemical composition and structure of the object to be preserved

DEVICE FOR MONITORING SAMPLE POSITIONING DURING MICROSCOPIC EXAMINATIONS

In this paper the design of a device for detecting the displacement of an object during microscopic studies is proposed. A detailed description of the device is given and an experi-mental assessment of its parameters is carried out.Исследование частично профинансировано в рамках поддержанного Российским научным фондом гранта № 20-72-00065