High-resolution short range ion detectors based on 4H-SiC films

The energy resolution of SiC detectors has been studied in application to the spectrometry of α particles with 5.1–5.5 MeV energies. The Schottky barrier structure of the detector was based on a CVD-grown epitaxial n-4H-SiC film with a thickness of 26 μm and an uncompensated donor concentration of (1–2)×10¹⁵ cm^?3. An energy resolution of 0.5% achieved for the first time with SiC detectors allows fine structure of the α particle spectrum to be revealed. The average energy of the electron-hole pair formation in 4H-SiC is estimated at 7.71 eV.     

The formation and study of sensor thin layers based on zirconium and rare earth metal (Ce,Y, and Tb) oxides and the preparation of metal-oxide-semiconductor structures based on them

Low-temperature synthetic methods (the molecular layering and pyrolysis of a liquid aerosol) for the nanostructured oxide films for the gas sensors based on zirconium dioxides and rare earth element (Ce, Y, and Tb) oxides sensitive to the oxygen-impoverished media and ozone have been suggested. It has been shown that the films based on the CeO₂-ZrO₂ and TbO _x -YO_1.5 systems possess the largest sensitivity and a strong response rate (5–6 s) to the reducing media (CO₂ + CO), while the film sensors based on CeO₂, to ozone. Metal-oxide-semiconductor (MOS) structures that find wide application in semiconductor microelectronics have been obtained based on the synthesized films of rare earth element oxides.     

High-temperature nuclear-detector arrays based on 4 <Emphasis Type="Italic">H</Emphasis>-SiC ion-implantation-doped <Emphasis Type="Italic">p</Emphasis><Superscript>+</Superscript>-<Emphasis Type="Italic">n</Emphasis> junctions

Results obtained in a study of spectrometric characteristics of arrays of four detectors based on 4H-SiC ion-implantation-doped p ⁺-n junctions in the temperature range 25–140 °C are reported for the first time. The junctions were fabricated by ion implantation of aluminum into epitaxial 4H-SiC layers of thickness ≤45 μm, grown by chemical vapor deposition with uncompensated donor concentration N _d ? N _a = (4–6) × 10¹⁴ cm^?3. The structural features of the ion-implantation-doped p ⁺-layers were studied by secondary-ion mass spectrometry, transmission electron microscopy, and Rutherford backscattering spectroscopy in the channeling mode. Parameters of the diode arrays were determined by testing in air with natural-decay alpha particles with an energy of 3.76 MeV. The previously obtained data for similar single detectors were experimentally confirmed: the basic characteristics of the detector arrays, the charge collection efficiency and energy resolution, are improved as the working temperature increases.     

Weibull-Gnedenko Distribution Parameters for Mechanical Characteristics of Single Aramid Arn Filaments After Treatment with Low-Concentration Carbon Nanotube Suspension

Fibre Chemistry - Weibull-Gnedenko distribution parameters for single filaments of copolymeric para-aramid fiber after treatment of its surface with a low-concentration aqueous suspension of...     

Photoelectric characteristics of silicon carbide–silicon structures grown by the atomic substitution method in a silicon crystal lattice

Data obtained in an experimental study of the photoelectric characteristics of silicon–silicon carbide structures grown by the atomic substitution method on silicon (100) and (111) substrates are presented. It is found that the maximum sunlight conversion efficiency of a silicon–silicon carbide (silicon carbide–silicon) heterojunction is 5.4%. The theory of dilatation dipole formation upon synthesis by the atomic substitution method is used to account for the mechanism of electrical barrier formation at the silicon–silicon carbide interface.     

Kinetics of crystallization of the metastable polytype of cerium upon melt quenching

Using a mathematical model of nonequilibrium crystallization of polymorphous metals with a narrow range of stability of the high-temperature modification, we have conducted numerical analysis of the kinetics of the formation of the metastable polytype of cerium (??-Ce) that is fixed by melt quenching at cooling rates more than ??10⁵ K/s. Agreement between the calculation data and the results of X-ray diffraction phase analysis of rapidly quenched foils has been obtained at a physically reasonable value of the model parameter having the meaning of the degree of metastability of ??-Ce.     

Analysis of Antidepressant-like Effects and Action Mechanisms of GSB-106, a Small Molecule,Affecting the TrkB Signaling

Induction of BDNF-TrkB signaling is associated with the action mechanisms of conventional and fast-acting antidepressants. GSB-106, developed as a small dimeric dipeptide mimetic of BDNF, was previously shown to produce antidepressant-like effects in the mouse Porsolt test, tail suspension test, Nomura water wheel test, in the chronic social defeat stress model and in the inflammation-induced model of depression. In the present study, we evaluated the effect of chronic per os administration of GSB-106 to Balb/c mice under unpredictable chronic mild stress (UCMS). It was observed for the first time that long term GSB-106 treatment (1 mg/kg, 26 days) during ongoing UCMS procedure ameliorated the depressive-like behaviors in mice as indicated by the Porsolt test. In addition, chronic per os administration of GSB-106 resulted in an increase in BDNF levels, which were found to be decreased in the prefrontal cortex and hippocampus of mice after UCMS. Furthermore, prolonged GSB-106 treatment was accompanied by an increase in the content of pTrkB^706/707 in the prefrontal cortex and by a pronounced increase in the level of pTrkB⁸¹⁶ in both studied brain structures of mice subjected to UCMS procedure. In summary, the present data show that chronic GSB-106 treatment produces an antidepressant-like effect in the unpredictable chronic mild stress model, which is likely to be associated with the regulation of the BDNF-TrkB signaling.     

Electron Microscopic Investigation of the Structure of Gas-Sensitive Nanocomposites Prepared by the Hydropyrolytic Method

Polycrystalline films in the SnO₂–In₂O₃ and SnO₂–ZnO systems, which are of interest for use in gas-sensitive sensors, are grown from metal chlorides on a 22-XC ceramic substrate by the hydropyrolytic method. The nanocomposites based on tin dioxide are studied. The structure of polycrystalline grains is investigated by electron spectroscopy and X-ray diffractometry. The distribution of components in the samples prepared is examined using electron probe X-ray microanalysis. It is established that homogeneous films in the SnO₂–In₂O₃ system up to 10 mol % In₂O₃ in the initial solution can be grown by the hydropyrolytic method.     

Preparation, Electrical Conductivity, and Sensory Properties of Oxide Films in the In2O3–SnO2 and In2O3–ZrO2 Systems

Nanostructured polycrystalline films in the In₂O₃–SnO₂ and In₂O₃–ZrO₂ systems, which are of interest for use in sensors for determining the content of strongly oxidizing media (such as ozone) and in electrode materials, are grown by the hydropyrolytic method from metal nitrates and through vacuum deposition of metals. Chemically interacting nanocomposites based on indium oxide are studied. The surface morphology of films and the structure of polycrystalline grains are investigated using electron microscopy and X-ray diffractometry.