Accretion bursts in magnetized gas-dust protoplanetary disks

Aims and Methods. Accretion bursts triggered by the magnetorotational instability (MRI) in the innermost disk regions were studied for protoplanetary gas-dust disks formed from prestellar cores of various mass $M_{\rm core}$ and mass-to-magnetic flux ratio $\lambda$. Numerical magnetohydrodynamics simulations in the thin-disk limit were employed to study the long-term ($\sim 1.0$~Myr) evolution of protoplanetary disks with an adaptive turbulent $\alpha$-parameter, which depends explicitly on the strength of the magnetic field and ionization fraction in the disk. The numerical models also feature the co-evolution of gas and dust, including the back-reaction of dust on gas and dust growth. Results. Dead zone with a low ionization fraction $x <= 10^{-13}$ and temperature on the order of several hundred Kelvin forms in the inner disk soon after its formation, extending from several to several tens of astronomical units depending on the model. The dead zone features pronounced dust rings that are formed due to the concentration of grown dust particles in the local pressure maxima. Thermal ionization of alkaline metals in the dead zone trigger the MRI and associated accretion burst, which is characterized by a sharp rise, small-scale variability in the active phase, and fast decline once the inner MRI-active region is depleted of matter. The burst occurrence frequency is highest in the initial stages of disk formation, and is driven by gravitational instability (GI), but declines with diminishing disk mass-loading from the infalling envelope. There is a causal link between the initial burst activity and the strength of GI in the disk fueled by mass infall from the envelope. Abridged.Comment: Accepted for publication in Astronomy & Astrophysic

Influence of uv radiation and discharge plasma on feed wheat seeds for acceleration of plants

In a rapidly changing unstable climate, the possible acceleration of plant growth and ripening is critical to food security in at least the region. This problem is especially relevant for areas with risky farming, which includes almost all of Siberia, and the Tomsk region in particular. Here we present the next results of a study of the effect of UV and ionizing radiation on cereals, namely, Iren wheat

Intrahippocampal pathways involved in learning/memory mechanisms are affected by intracerebral infusions of amyloid-beta25-35 peptide and hydrated fullerene C60 in rats

Primary memory impairments associated with increased level of amyloid-beta (Аβ) in the brain have been shown to be linked, partially, with early pathological changes in the entorhinal cortex (EC) which spread on the whole limbic system. While the hippocampus is known to play a key role in learning and memory mechanisms, it is as yet unclear how its structures are involved in the EC pathology. In this study, changes in memory and neuronal morphology in male Wistar rats intrahippocampally injected with Аβ25–35 were correlated on days 14 and 45 after the injection to reveal specific cognitive - structural associations. The main focus was on the dentate gyrus (DG) and hippocampal areas of CA1 and CA3 because of their involvement in afferent flows from EC to the hippocampus through tri-synaptic (EC DG CA3 CA1) and/or mono-synaptic (EC CA1) pathways. Evident memory impairments were observed at both time points after Аβ25–35 injection. However, on day 14, populations of morphological intact neurons were decreased in CA3 and, drastically, in CA1, and the DG supramedial bundle was significantly damaged. On day 45, this bundle largely and СА1 neurons partially recovered, whereas CA3 neurons remained damaged. We suggest that Аβ25–35 primarily affects the tri-synaptic pathway, destroying the granular cells in the DG supramedial area and neurons in CA3 and, through the Schaffer collaterals, in CA1. Intrahippocampal pretreatment with hydrated fullerene С60 allows the neurons and their connections to survive the amyloidosis, thus supporting the memory mechanisms

Spatial memory deficits initiated by agroclavine injection or olfactory bulbectomy in rats are characterized by different levels of long-term potentiation expression in the hippocampus

Aim: To clarify whether long-term potentiation (LTP) is the mechanism underpinning mnemonic processes. Mathrials and methods: We studied LTP in hippocampal slices from rats whose spatial memory deficit was produced by either olfactory bulbectomy (OBX) or pretreatment with an ergot alkaloid, agroclavine. OBX is accompanied by cholinergic system inhibition whereas agroclavine predominantly activates dopaminergic mediation. The both have been shown to be involved in learning/memory and LTP mechanisms. Results: In OBX- vs. sham-operated rat, we have revealed significant reduction of LTP in hippocampal CA1 region. In contrast, no LTP differences in agroclavine- vs. vehicle-treated rats were observed. Conclusions: These results demonstrate that LTP expression in the hippocampus is dependent on the origin of spatial memory impairment. Furthermore, they suggest that pharmacological and neurodegenerative models of AD might be useful approach for discovery of both AD mechanisms and mixed pathology dementias

ITO-free silicon-integrated perovskite electrochemical cell for light-emission and light-detection

Halide perovskite light-emitting electrochemical cells are a novel type of the perovskite optoelectronic devices that differs from the perovskite light-emitting diodes by a simple monolayered architecture. Here, we develop a perovskite electrochemical cell both for light emission and detection, where the active layer consists of a composite material made of halide perovskite microcrystals, polymer support matrix, and added mobile ions. The perovskite electrochemical cell of CsPbBr3:PEO:LiTFSI composition, emitting light at the wavelength of 523 nm, yields the luminance more than 7000 cd/m2 and electroluminescence efficiency of 1.3×105 lm/W. The device fabricated on a silicon substrate with transparent single-walled carbon nanotube film as a top contact exhibits 40% lower Joule heating compared to the perovskite optoelectronic devices fabricated on conventional ITO/glass substrates. Moreover, the device operates as a photodetector with a sensitivity up to 0.75 A/W, specific detectivity of 8.56×1011 Jones, and linear dynamic range of 48 dB. The technological potential of such a device is proven by demonstration of 24-pixel indicator display as well as by successful device miniaturization by creation of electroluminescent images with the smallest features less than 50 μm

Low power reconfigurable multilevel nanophotonic devices based on Sn-doped Ge2Sb2Te5 thin films

In the past years, Ge2Sb2Te5 has been considered a promising functional material for a variety of reconfigurable multilevel devices, including photonic integrated circuits for the post-von Neumann arithmetic processing. However, despite significant advances, it is necessary to reduce the switching energy of Ge2Sb2Te5 for creation of the on-chip low power all-photonic spiking neural networks. The present work focuses on the effect of tin ion implantation on the properties of amorphous Ge2Sb2Te5 thin films, as well as on the performance of Mach-Zehnder interferometers and balanced beam splitters based on them. As a result, Sn-doping accompanied by the formation of weaker bonds in Ge2Sb2Te5 thin films is an efficient approach to significantly reduce the threshold energy of fs-laser initiated phase transitions and change the effective absorption coefficient. The possibility of using the Sn-doped Ge2Sb2Te5 thin films for fully optical multilevel reversible recording between 9 different levels (3 bits) has been demonstrated by experimental measurements of fabricated on-chip balanced beam splitters. The obtained results show that the Sn doping of Ge2Sb2Te5 layer can be used to optimize the properties of the GST225 thin films, in particular to reduce the switching energy. So, it has the potential to improve the characteristics of reconfigurable multilevel nanophotonic devices using the GST225 thin films, including fully non-volatile memory and developed on-chip low power all-photonic circuits for post-von Neumann arithmetic processin

Hydrothermal Transformations of Lanthanum Phosphate with iron(3+) Oxides (Hydroxides) in Acidic Solutions

Получены данные по влиянию природы минеральных кислот на показатели вскрытия фосфата лантана новым методом – гидротермальным кислотным растворением фосфата лантана при температуре 180–220 °C в присутствии оксидов (гидроксидов) железа(3+). Установлено, что из изученных кислот – азотной, хлористоводородной и серной – эффективное извлечение лантана с глубоким обесфосфориванием растворов достигается лишь для азотной кислоты. В этой системе извлечение лантана в раствор составляет 97–98 %, а содержание фосфора снижается до 10 мг/л и менее за счет образования устойчивого гидроксифосфата железа(3+) – гиниита. Для соляной кислоты наблюдается преимущественный переход в раствор железа(3+) за счет комплексообразования его с хлорид-ионами, а показатели извлечения в раствор лантана не превышали 5 %. Содержание фосфора в растворе также существенно выше, чем для азотной кислоты. При использовании серной кислоты образуются малорастворимые гидроксисульфаты. Фазы образования гиниита не наблюдаются, а извлечение в раствор лантана не превышает 10 % для концентрации серной кислоты 4 моль/лData on the influence of the nature of mineral acids on the indicators of lanthanum phosphate opening by a new method – hydrothermal acid dissolution of lanthanum phosphate at a temperature of 180–220 °C in the presence of iron(3+) oxides (hydroxides) have been obtained. It has been established that from the studied acids – nitric, hydrochloric and sulfuric, effective extraction of lanthanides with deep dephosphorization of solutions is achieved only for nitric acid. In this system, the extraction of lanthanum into solution is 97–98 %, and the phosphorus content is reduced to 10 mg/L or less due to the formation of stable iron(3+) hydroxyphosphate – giniite. For hydrochloric acid, a preferential transition to iron(3+) solution is observed due to its complexation with chloride ions, and the extraction rates of lanthanum into the solution did not exceed 5 %. The content of phosphorus in the solution is also significantly higher than for nitric acid. When using sulfuric acid, sparingly soluble hydroxysulfates are formed. The phase of gyniite formation is not observed, and the extraction of lanthanum into solution does not exceed 10 % for a sulfuric acid concentration of 4 mol/

Development of methodology and devices for the measurement of acoustic characteristics of small-size pottery work

Sperimens in the form of plates from polycrystal lithobromide, aluminooxide, aluminonitride ceramics are considered in the paper aiming at the creation of the methodology and devices for the measurement of acoustic characteristics of real pottery work of small sizes, having plane-parallel sides. As a result the Q-factor measurement possibility and perspectivity of small-size ceramic plates with imperfect geometry in megattertz frequency range have been shown theoretically. The effective algorithm, making it possible to analyze the system, consisting of an arbitrary number of piezoactive lavers with the consideration of the elastic wave attenuation has been developed. The Q-factor of real lithobromide, aluminooxide and aluminonitride pottery work in megattertz frequency range has been measured for the first time. The possibility of the methodology creation for the electronics pottery non-destroying control has been shown. The paper results have been used in the control of the glass and glass ceramic making processAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Dipole Approximation in the Calculation of the Perturbed Velocities

In this article we consider one of the approaches aimed at reducing time of calculation of aerodynamic characteristics of the studied objects using discrete vortex method. Also, accuracy assessment of calculation of aerodynamic characteristics was performed

Oil decontamination of bottom sediments experimental work results

This article presents the results of experimental work during 2004-2005 on oil decontamination of bottom sediments of Lake Schuchye, situated in the Komi Republic (Northern Russia). The cause of thecontamination were huge oil spills occurred after a series of accidental ruptures on the Harjaga-Usinsk and Vozej-Usinsk oil-pipe lines in 1994. Flotation technology was used for the cleaning of bottom sediments.157 tons of crude oil were removed during the course of 2-year experimental work from an area of 4,1 ha.The content of aliphatic and alicyclic oil hydrocarbons was reduced from 53,3 g/kg to 2,2 g/kg, on average.Hydrobiological investigations revealed that bottom sediments started to be inhabited by benthos organisms, dominantly Oligochaeta. Besides Oligochaeta, Chironomidae maggots and Bivalvia were detected. Theappearance of Macrozoobenthos organisms can serve as a bioindicator of water quality