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Here we report ongoing efforts for an untriggered search of rapid optical transients of various astrophysical and non-astrophysical origins on time scales down to fractions of a second with Mini-MegaTORTORA. Mini-MegaTORTORA is a novel 9-channel wide-field optical monitoring system in operation since 2014 at Special Astrophysical Observatory on Russian Caucasus.
We briefly describe our on-going investigation of the near-IR luminosity-metallicity relationship for dwarf irregular galaxies in nearby groups of galaxies. The motivations of the project and the observational databases are introduced, and a preliminary result is presented. The 12 + log(O/H) vs. H plane must be populated with more low-luminosity galaxies before a definite conclusion can be drawn.
We conducted infrared spectroscopic observations of bright stars in the direction of the molecular clouds W33 and GMC G23.3 − 0.3. We compared stellar spectro-photometric distances with parallactic distances to these regions, and we were able to assess the association of the detected massive stars with these molecular complexes. The spatial and temporal distributions of the detected stars enabled us to locate sources of ionizing radiation and to gather precise information on the star formation history of these clouds. The studied clouds present different distributions of massive stars.
A plasma target for highly efficient neutralization of powerful negative ion beams is considered. The plasma is confined within a magnetic trap with multipole magnetic walls. It is proposed to use inverse magnetic mirrors to limit plasma outflow through the inlet and outlet holes in the trap. Using the particle-in-cell method, mathematical simulation of plasma dynamics in the trap has been performed. The estimates of plasma distribution and particle confinement efficiency in the region of the magnetic mirrors has been obtained. Simulation results were compared with experimental data.
This report summarizes epidemiological data on nephropathia epidemica (NE) in the Republic of Tatarstan, Russia. NE cases identified in the period 1997–2013 were investigated in parallel with the hantavirus antigen prevalence in small rodents in the study area. A total of 13 930 NE cases were documented in all but one district of Tatarstan, with most cases located in the central and southeastern districts. The NE annual incidence rate exhibited a cyclical pattern, with the highest numbers of cases being registered once in every 3–5 years. The numbers of NE cases rose gradually from July to November, with the highest morbidity in adult males. The highest annual disease incidence rate, 64·4 cases/100 000 population, was observed in 1997, with a total of 2431 NE cases registered. NE cases were mostly associated with visiting forests and agricultural activities. The analysis revealed that the bank vole Myodes glareolus not only comprises the majority of the small rodent communities in the region, but also consistently displays the highest hantavirus prevalence compared to other small rodent species.
Our recent efforts using primarily nanodiamonds as lubricant additives are discussed. For traditional high performance engine oils, our results show a reduction in friction for steel surfaces for both laboratory experiments under controlled conditions and in a pilot study of passenger cars under typical driving conditions. Examination of the surfaces suggests that surface polishing at the sub-micron scale may be responsible for these results. A separate set of experiments using a quartz crystal microbalance to measure dissipation and drag due to friction has shown that when added to water the charge of the nanodiamond acquired from surface functionalization can have a large influence on uptake and friction at the water-metal interface. More importantly, these results suggest the possibility of creating nanodiamonds with controllable frictional drag at the solid-liquid interface through surface processing. Companion simulation results for nanodiamonds in water sliding between diamond surfaces are also presented. Future possibilities for further understanding and tuning the properties of nanodiamonds as lubricant additives through synergistic experiments and modeling are also discussed.
Here we briefly summarize our long period experience of constructing and operating
wide-field monitoring cameras with sub-second temporal resolution to look for optical
components of GRBs, fast-moving satellites and meteors. General requirements for hardware
for such systems are discussed along with algorithms of real-time detection and
classification of various kinds of short optical transients. We also give a status report
on the next generation, multi-objective and transforming monitoring system, the
MegaTORTORA, whose 6-channel (Mini-MegaTORTORA-Spain) and 9-channel
prototypes (Mini-MegaTORTORA-Kazan) we are building now at SAO RAS. This system combines a
wide field of view with subsecond temporal resolution in monitoring regime, and is able to
reconfigure itself, in a fractions of second, to follow-up mode which has better
sensitivity and provides us with multi-color and polarimetric information on detected
A reprocessing of uranium hexafluoride waste, which was accumulated in the
nuclear industry for many years, is a very vital question now. There are a
lot of gas tanks filled with UF6 that have been exposed for a
long time and are posing a serious ecological danger. A plasma chemical
technique is proposed here to transform the uranium hexafluoride depleted
with isotope 235U (less than 0.1%) into the safe storage form -
powdered uranium oxides. The second product is HF (70–80% aqueous solution)
which may be easily reprocessed by means of the rectification column up to
pure anhydrous hydrogen fluoride.
The designed technological scheme and the basic technical characteristics of
the plasma chemical converter are presented. The proposed technique is
efficient, easy controlled and free of any harmful by-products.
More than 20000 observations of Near Earth asteroids and comets are collected and reduced in Pulkovo Observatory during last 10 years. For observations of these objects two robotic telescopes are used – ZA-320M (Cassegrain system, D = 320 mm, F = 3200 mm) at Pulkovo and MTM-500M (Maksutov – Cassegrain system, D = 500 mm, F = 4100 mm) at Kislovodsk mountain station. These telescopes perform CCD observations of objects up to 18.0 and 20.5 magnitude, correspondingly. The results of observations are regularly submitted to Minor Planet Center.
During the first half of the twentieth century, widespread regulatory efforts to control cattle brucellosis due to Brucella abortus in the Union of Soviet Socialist Republics were essentially non-existent, and control was limited to selective test and slaughter of serologic agglutination reactors. By the 1950s, 2–3 million cattle were being vaccinated annually with the strain 19 vaccine, but because this vaccine induced strong, long-term titers on agglutination tests that interfered with identification of cattle infected with field strains of B. abortus, its use in cattle was discontinued in 1970. Soviet scientists then began a comprehensive program of research to identify vaccines with high immunogenicity, weak responses on agglutination tests and low pathogenicity in humans, as a foundation for widespread control of cattle brucellosis. While several new vaccines that induced weak or no responses on serologic agglutination tests were identified by experiments in guinea pigs and cattle, a large body of experimental and field studies suggested that the smooth–rough strain SR82 vaccine combined the desired weak agglutination test responses with comparatively higher efficacy against brucellosis. In 1974, prior to widespread use of strain SR82 vaccine, over 5300 cattle farms across the Russian Federation were known to be infected with B. abortus. By January 2008, only 68 cattle farms in 18 regions were known to be infected with B. abortus, and strain SR82 continues to be the most widely and successfully used vaccine in many regions of the Russian Federation.
We performed group-theoretical analysis of the symmetry relationships between lattice structures of R, M1, M2, and T phases of vanadium dioxide in the frameworks of the general Ginzburg-Landau phase transition theory. The analysis leads to a conclusion that the competition between the lower-symmetry phases M1, M2, and T in the metal-insulator transition is pure symmetry driven, since all the three phases correspond to different directions of the same multi-component structural order parameter. Therefore, the lower-symmetry phases can be stabilized in respect to each other by small perturbations such as doping or stress.
A hybrid double heterostructure with large asymmetric band offsets, combining AlAsSb/InAs (as a III–V part) and CdMgSe/CdSe (as a II–VI part), has been proposed as a basic element of a mid-infrared laser structure design. The p-i-n diode structure has been successfully grown by molecular beam epitaxy (MBE) and exhibited an intense long-wavelength electroluminescence at 3.12 μm (300K). A II–VI MBE growth initiation with a thin ZnTe buffer layer prior to the CdMgSe deposition results in a dramatic reduction of defect density originating at the II–VI/III–V interface, as demonstrated by transmission electron microscopy. A less than 10 times reduction of electroluminescence intensity from 77 to 300K indicates an efficient carrier confinement in the InAs active layer due to high potential barriers in conduction and valence bands, estimated as ΔEC = 1.28 eV and ΔEV ∼ 1.6 eV. An increase in the pumping current results in a super-linear raising the EL intensity. The type of band line up at the coherent InAs/Cd1−xMgxSe interface is discussed for 0≤x≤0.2, using experimental data and theoretical estimations within a model-solid theory.
Stressor-controlled epitaxy has been proposed as an efficient method of CdSe quantum dot fabrication. The studies are performed on a type-II CdSe/BeTe system, where CdTe and BeSe inteface bonds play a role of intrinsic stressors. Predeposition of ~0.2 ML CdTe stressor ( Δ a/a= +15%), corresponding to a local maximum of RHEED specular spot intensity, appears to induce variation of stress field across the BeTe surface, caused by alternating regions with CdTe and BeSe bonds. It results in preferential nucleation of regularly arranged CdSe QDs at the BeSe sites with the following vertical chess-ordering in the CdSe/BeTe multilayers. The structures demonstrate bright up to RT PL in the 1.9-2.1 eV range and strong in-plane PL anisotropy related to non-equivalent bottom and top CdSe QD interfaces having estimated from x-ray diffraction total concentrations of CdTe and BeSe bonds of 0.3-0.4 and 0.6-0.7 ML, respectively.
The nanocrystalline samples of 10wt.%Scandia stabilized Zirconia (10ScSZ) and 1wt.%Ceria doped ScSZ (1Ce10ScSZ) prepared via co-precipitation route were characterized and compared to commercially available samples regarding their transport properties and electrical conductivity. The results of oxygen isotope experiments show that for Zirconia-based electrolytes, the rate of heteroexchange is lower than that for Samaria-doped Ceria. The results of Secondary Ions Mass Spectrometry (SIMS) indicate that all admixed components are present both in the surface layer and the bulk of the studied samples with pronounced segregation on the grain boundary. The highest total conductivity is observed for DKKK sample. In the range of 600-400°C the highest conductivity observed for synthesized nanocrystalline 1Ce10ScSZ sample is explained by the effect of segregated Scandia doped Ceria surface layers.
Further progress in IC dimension reduction, increase in integration degree and speed require development and use of new current-conducting materials. This is due to the fact that existing current-conducting systems based on aluminium are low temperature, characterized by low electromi gration stability and require use of complex barrier layersi[l]. Polycide currentconducting materials have quite high resistance, interact with aluminium and are sensitive to the formation conditions. From this point of view, borides and titanium borides in particular are very promising for making current-conducting systems since they are very much characterized by good barrier properties, high conductance, properties and electromigration stability .
Ca and/or F-modified samples of LaMnO3 have been prepared by the Pechini method. The bulk structure of samples was characterized by TEM, EXAFS and XRD, while the surface composition was studied by SIMS. Thermal analysis, O2 TPD, H2 TPR and isothermal pulse/flow samples reduction by CO were applied to characterize the accessible surface/bulk oxygen mobility and reactivity. A reasonable description of the experimental energetic spectrum of the surface oxygen for various types of regular and defect surface sites on the perovskite faces was achieved by using semiempirical Interacting Bonds Method in the slab approximation with a due regard for the surface face termination and relaxation. Fluorine was found to decrease the surface coverage by reactive weakly bound oxygen forms while increasing the bulk oxygen excess and mobility. Calcium generated reactive weakly bound oxygen forms while decreasing the oxygen excess in the lattice and converting the regular M-O oxygen forms into the bridging ones through migration to the surface.
Bulk and surface properties of dispersed partially stabilized zirconias (PSZ) prepared via coprecipitation of zirconium and alkaline-earth metal hydroxides have been studied by XPD, SIMS, IR spectroscopy of surface hydroxyls and adsorbed C.O. For Sr- and Ca-PSZ, the number of the Lewis acid centers, surface concentration of the guest cation and Zr-O bonding strength at the surface have been found to deviate substantially from the values predicted by a bulk truncation model, while for Ba-PSZ it seems to be valid. A local reconstruction of the near-surface layer into the perovskite-like structure was proposed for the first two systems, which explained satisfactorily their surface properties including catalytic performance in the selective reduction of nitrogen oxides by propane in the excess of oxygen. Such reconstruction is probably facilitated by segregation of the guest cations in the subsurface layer. The driving force for this process depends upon site preference of the alkaline-earth cations to cubooctahedrons and steric factors.
A comparative analysis of different Cd1−xZnxTe (CZT) crystals grown by a vertical high pressure Bridgman (VHPB) method is reported. The results of several analytical techniques, such as triple axis x-ray diffraction (TAD), rocking curves, low temperature photoluminescence (PL), scanning electron microscopy (SEM), and proton induced x-ray emission (PIXE) are discussed. Segregated carbon inclusions were identified by SEM and energy dispersive x-ray fluorescence (EDXRF), and the results are interpreted in terms of constitutional supercooling of the solidifying CZT melt. The carbon inclusions significantly decrease the resistivity, and in some cases, the noise is too large for the fabrication of radiation detectors. Combining these results with other measurements reported by our research team , we identify correlations between the growth and the defects identified in these CZT crystals.
Several analytical techniques have been used in the study of the homogeneity of Cadmium Zinc Telluride (CZT) single crystals grown by the vertical high pressure Bridgman (VHPB) method. The presence of black inclusions and tubular hollow pipes has been observed by a few methods, such as photoluminescence (PL), infrared (IR) transmission microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystals investigated were grown commercially in the USA, at the Institute of Single Crystals in Kharkov, Ukraine, and at the Institute of Solid State Physics, Moscow, Russia. We discuss the homogeneity of the various CZT crystals based on the results from these measurement techniques.