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•Calcination in N2 preserves the supports structure better than calcination in air.•The presence of Na in catalyst promotes SiC oxidation and catalyst sintering.•CH4 conversion and C2 ...yield scale roughly linear with the specific surface area.•SiC as a support shows a higher CH4 conversion and C2 yield per m2 of surface area than SiO2.
Efficient conversion of methane to higher hydrocarbons via oxidative coupling of methane “OCM” is one of the dream reactions in heterogeneous catalysis. Promising yields of C2 hydrocarbons were reported for nanostructured catalysts based on Mn/Na/W-SiO2. However, the exact role of the nanostructure could not be studied so far due to collapse of the pore structure of the SiO2 support at typical OCM temperatures. We investigate porous SiC as an alternative catalyst support for OCM catalysis. Mn/Na/W/SiC catalysts with different pore size were synthesized via impregnation, calcined under different atmospheres and then studied in OCM. The calcination critically impacts the pore structure and surface area of the obtained catalysts. Calcination in nitrogen preserves the support’s structure significantly better than calcination in air. However, the nitrogen-calcined catalysts show a strong loss of porosity during OCM testing. The loss of porosity is caused by the presence of Na, which induces a melting of the surface layer that typically protects SiC against bulk oxidation. OCM tests suggest that the activity and C2 yield of Mn/Na/W/SiC catalysts depend critically on the supports stability, i.e. the surface area retained under reaction conditions.
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The South Anyui Fold System was formed at the end of the Early Cretaceous at the site of a closed oceanic basin as a result of the collision of the Chukotka microcontinent with the structures of ...the active margin of the Siberian continent. There are two distinct stages in the tectonic history of the oceanic basin. At the first stage (Late Paleozoic–Early Mesozoic), there was the Proto-Arctic Ocean, which united the South Anyui and Angayucham basins. The second stage (Volgian–Hauterivian–Barremian) began with cessation of spreading, the shortening of the oceanic basin, and accumulation of turbidites. In the west, the South Anyui Suture ends in the Khroma Loop and, like the Kolyma Loop, the suture is a package of allochthons composed of fragments of the Proto-Arctic Ocean. In the central part, the suture is the result of the collision of the Chukotka microcontinent with the active margin of the Kolyma–Omolon microcontinent. The eastern end of the collisional suture is formed by ophiolites in the Matachingai River basin. The Late Triassic–Early Jurassic ensimatic island arcs of the Velmay Terrane accreted to the Chukotka microcontinent in eastern Chukotka. In this area, the Proto-Arctic Ocean connected with the Meso-Pacific Ocean, from where the island-arc terranes were transported. The South Anyui Suture is the border of the Verkhoyansk–Kolyma and Chukotka fold regions and, accordingly, the border of the Pacific and Arctic structures. There are significant differences in the tectonic evolution of these structures, which are determined by the different history and age of the Proto-Arctic and Oymyakon paleoceans, fragments of which were preserved in the Khroma and Kolyma structural loops, as well as the patterns of sedimentation on the Verkhoyansk and Chukotka passive margins, which belonged to the Siberia and Laurentia paleocontinents.
Using an original method, we have received
Drosophila melanogaster
with a deficiency including a complete sequence of
quick-to-court
gene. In this report, we describe the behavioural features of this ...new deletion mutant. There were no serious deviations from the normal mating behaviour in flies with the deletion, but the behaviour of deletion mutants still had some features. Of all the elements, only the frequency of licking significantly increased in mutants. The duration of mating elements did not change in flies with deletion, and the latent period decreased only for following the female and licking. We have found that mutant males produce more courtship song than control males when courting
Oregon R
females as estimated by the pulse song index. In our experiment, mutant females provoked much less pulse song production by
Oregon R
males than control females do. Moreover,
Oregon R
males initiate courtship song towards mutant females later than towards control females. In other words, the study of pulse song production showed that the deficiency in females leads to a decrease in the intensity of courtship of wild-type males, whereas the deficiency in males leads to more intensive care for wild-type females.
У The problem of distribution of a set of objects, the state of which is determined by a set of controlled parameters, into a set of subsets of objects maximally homogeneous in their properties is ...considered. Relevance of the problem and important advantage of the clustering procedure: when its implementing it is possible to reduce the initial difficult problem of high dimensionality objects analysing to the solution of a number of simpler problems of lower dimensionality. This circumstance acquires additional attractiveness and importance if the initial data of the problem contain uncertainty, for example, are vaguely defined. Research object is the procedure of partitioning a set of objects into clusters under conditions of uncertainty. In this regard, the purpose of the study is to develop a method for solving the problem of clustering in conditions where the initial data on objects controlled parametersthe values contain uncertainty. The method of solving the problem is based on clustering procedure mathematical model development, containing analytical expressions for the criterion of its effectiveness, written in the form of a twice fractionally quadratic function. The impossibility of mathematical programming problem direct solution initiated the development of a heuristic algorithm for its solution. As a result, an iterative method was obtained and applied to solve the clustering problem under conditions of fuzzy initial data. The developed computational procedure is based on a reasonable system of rules for performing operations on fuzzy numbers. The situations when the belonging functions of problem fuzzy parameters are defined on infinite or compact media are considered. The developed system of rules allows to correctly perform operations in the metric of fuzzy defined states between clustering objects. The proposed method is easily generalised to the case when the uncertainty of the initial data is hierarchical.
Non-destructive measurements of internal morphological structures in plant materials such as seeds are of high interest in agricultural research. The estimation of pericarp thickness is important to ...understand the grain quality and storage stability of seeds and can play a crucial role in improving crop yield. In this study, we demonstrate the applicability of fiber-based Bessel beam Fourier domain (FD) optical coherence microscopy (OCM) with a nearly constant high lateral resolution maintained at over ~400 µm for direct non-invasive measurement of the pericarp thickness of two different sorghum genotypes. Whereas measurements based on axial profiles need additional knowledge of the pericarp refractive index, en-face views allow for direct distance measurements. We directly determine pericarp thickness from lateral sections with a 3 µm resolution by taking the width of the signal corresponding to the pericarp at the 1/e threshold. These measurements enable differentiation of the two genotypes with 100% accuracy. We find that trading image resolution for acquisition speed and view size reduces the classification accuracy. Average pericarp thicknesses of 74 µm (thick phenotype) and 43 µm (thin phenotype) are obtained from high-resolution lateral sections, and are in good agreement with previously reported measurements of the same genotypes. Extracting the morphological features of plant seeds using Bessel beam FD-OCM is expected to provide valuable information to the food processing industry and plant breeding programs.
We present a description of a plasma-chemical facility designed for synthesis of micro- and nanoparticles using the radiation of a high-power gyrotron. The facility has been developed at the Plasma ...Physics Division of A.M.Prokhorov General Physics Institute of the Russian Academy of Sciences. The facility includes a plasma-chemical reactor, a gyrotron unit, an in-line calorimeter, a diagnostic system, which ensures video and spectroscopic measurements, balance measurements of the microwave radiation, and thermal imagery measurements, a chemical unit for specimen preparation and analysis of synthesis products, an electronic logging unit, and a specimen labeling system for organization and storage of a large amount of experimental data and specimens.
That irradiated cells affect their unirradiated 'bystander' neighbors is evidenced by reports of increased clonogenic mortality, genomic instability, and expression of DNA-repair genes in the ...bystander cell populations. The mechanisms underlying the bystander effect are obscure, but genomic instability suggests DNA double-strand breaks (DSBs) may be involved. Formation of DSBs induces the phosphorylation of the tumor suppressor protein, histone H2AX and this phosphorylated form, named gamma-H2AX, forms foci at DSB sites. Here we report that irradiation of target cells induces gamma-H2AX focus formation in bystander cell populations. The effect is manifested by increases in the fraction of cells in a population that contains multiple gamma-H2AX foci. After 18 h coculture with cells irradiated with 20 alpha-particles, the fraction of bystander cells with multiple foci increased 3.7-fold. Similar changes occurred in bystander populations mixed and grown with cells irradiated with gamma-rays, and in cultures containing media conditioned on gamma-irradiated cells. DNA DSB repair proteins accumulated at gamma-H2AX foci, indicating that they are sites of DNA DSB repair. Lindane, which blocks gap-junctions, prevented the bystander effect in mixing but not in media transfer protocols, while c-PTIO and aminoguanidine, which lower nitric oxide levels, prevented the bystander effect in both protocols. Thus, multiple mechanisms may be involved in transmitting bystander effects. These studies show that H2AX phosphorylation is an early step in the bystander effect and that the DNA DSBs underlying gamma-H2AX focus formation may be responsible for its downstream manifestations.
The results of critical and correlation experiments with a plutonium metal multiplying assembly in a depleted uranium all-round reflector are compared with the results of their numerical simulations ...by the Monte Carlo method using PRIZMA-D and PRIZMA programs with the ENDF-B6.8 and ENDF-B7.1 libraries of neutron constants.
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