The study examined the possibility of using the phytoindication technique to describe habitat preferences of red deer in a relatively homogeneous area. Two alternative hypotheses were tested. ...Hypothesis 1 suggests that the relationship between red deer and vegetation is due to a trophic factor, so preferences for individual plant species cause vegetation to influence the distribution of animal numbers. Hypothesis 2 suggests that environmental factors influence vegetation, structuring and determining the productive level of the community as a whole. Therefore, environmental factors, rather than individual plant species, cause vegetation-animal interactions. The research was conducted on Biryuchiy Island Spit, where the Azov-Sivash National Nature Park is located. The geobotanical surveys were performed in three types of ecosystems: sandy steppe (vegetation class Festucetea vaginatae), saline meadows (vegetation class Festuco-Puccinellietea), and artificial forest plantation (vegetation class Robinietea). 250 releves were recorded according to the Brown-Blanquet approach. The number of fecal pellets and the number of groups of pellets of red deer was recorded together with geobotanical surveys in the same sample plots. The pellet groups counted in the field were converted to deer densities in specific vegetation classes taking into account the number of pellet groups on the site and the deca rate of the fecal pellets. The vegetation types were distinguished by the number of deer fecal pellets per unit area. The highest number of fecal pellets was found for the plant class Festucetea vaginatae, somewhat fewer fecal pellets were in the plant class Robinietea, and the lowest number was in the plant class Festuco-Puccinellietea. A geometric distribution model is adequate for explaining the experimental data on the number of fecal pellets. A total of 59 species of flowering plants were found. Based on the species composition and projective cover of species, the ecological regimes of ecotopes were identified by phytoindication. The correspondence analysis of the vegetation revealed two ordination axes. The ordination axis 1 (CA1) was able to explain 11.3% of community inertia, and the ordination axis 2 (CA2) was able to explain 5.2% of community inertia. The maximum excretory activity of animals was recorded for the central part of the ordination space, indicating the presence of an optimum zone in the gradient of environmental factors that structure plant communities. The forward selection procedure allowed the Nutrients Availability variable to be selected as the most important variable to explain variation in the plant community structure. The number of deer fecal pellets exhibited different patterns of response in the Nutrients Availability gradient. The response within the plant class Festucetea vaginatae could best be explained by Model III from the list of HOF-models. The response of the excretory activity of deer within the class Festuco-Puccinellietea could best be fitted by the model IV, which represents a symmetric Gaussian curve. The response of excretory activity in the Robinietea vegetation class was asymmetrical bimodal. The ecological properties of the red deer ecological niche in both the drier and less mineralized part of the range of ecological conditions and the wetter and more mineralized part should be assessed in the context of the prospects for future studies.
•ζ-factor microanalysis was successfully applied to quantify boron-rich ceramics.•A full range of ζ-factors were experimentally determined and validated.•Strategies to best determine boron carbide ...bulk stoichiometry were compared.•Boron carbide specimens with different stoichiometries were determined.•A ζ-factor raster scan technique was used to determine grain boundary compositions.
Accurate quantification of light elements which produce only soft X-ray lines via X-ray energy dispersive spectrometry (XEDS) has been traditionally difficult due to poor X-ray emission and detector efficiencies at low energies and significant X-ray absorption effects. The ζ-factor microanalysis method enables one to correct for these shortcomings; however, ζ-factor microanalysis has not yet been thoroughly applied to inorganic materials which are entirely or mostly composed of light elements such as boron carbide, boron nitride, or boron suboxide. This work successfully extended ζ-factor microanalysis to boron-rich ceramics and accurately determined stoichiometries of multiple boron carbides and measured grain boundary compositions of a boron carbide mixed with additives consisting of rare-earth ions. Various strategies were employed to experimentally determine a full range of ζ-factors and measurements were validated using materials of known composition including silicon hexaboride and silicon carbide. Overall, this work has shown that XEDS is a viable technique for light element quantification in (scanning) transmission electron microscopy, in terms of both the accuracy and precision, which is comparable or superior to the complementary electron energy loss spectrometry.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A systematic study of mechanical deformation of boron carbide under contact loading is conducted using scratching and depth-sensing indentation (nanoindentation). Both single crystal and ...polycrystalline materials are investigated by means of Raman microspectroscopy and transmission electron microscopy (TEM). High resolution TEM images of scratch debris reveal various microstructural changes including formation of nanocrystals, as well as lattice shearing and distortion on nanoscale. Deformation bands and microcracks oriented along the (1
1
3) planes are visible in cross-sectional TEM micrographs of indentations. Narrow amorphous bands and local disordered areas are observed in plan-view TEM images. Evidence for a high-pressure amorphous phase is also presented. It is concluded that scratching and nanoindentation change the microstructure of boron carbide in a similar manner. In addition, the evidence for formation of sp
2 hybridized carbon as a result of structural changes induced by contact loading is found by electron energy loss spectroscopy (EELS).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, certain problems of taxonomy and etymology associated with the borrowings from indigenous languages into American English have been solved. The vocabulary of Amerindian and ...Eskimo-Aleut languages of the indigenous ethnic groups of North, South, and Central America in American English are the research material. After analyzing the etymological sources of autochthonous lexical units in AmE, it has been found that the process of borrowing lasted for five centuries (XVI–XX centuries). Despite this fact, the most part of the vocabulary has been lost in the absence of nomination objects, substituted by English synonyms or moved into the category of archaisms and historicisms and has not kept its relevance to the English-speaking usage. However, the author of this article has analyzed native lexical units, which are an integral part of the lexical system of modern American English; this fact is confirmed by the necessary introduction of the given lexical items into the register of authoritative lexicographical sources: references, explanatory dictionaries, and special dictionaries describing the lexical structure of modern AmE.
Boron carbide is characterized by a unique combination of properties that make it a material of choice for a wide range of engineering applications. Boron carbide is used in refractory applications ...due to its high melting point and thermal stability; it is used as abrasive powders and coatings due to its extreme abrasion resistance; it excels in ballistic performance due to its high hardness and low density; and it is commonly used in nuclear applications as neutron radiation absorbent. In addition, boron carbide is a high temperature semiconductor that can potentially be used for novel electronic applications. This paper provides a comprehensive review of the recent advances in understanding of structural and chemical variations in boron carbide and their influence on electronic, optical, vibrational, mechanical, and ballistic properties. Structural instability of boron carbide under high stresses associated with external loading and the nature of the resulting disordered phase are also discussed.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
In the literature, there is insufficient information on the synthesis of compounds in a series of pyrimidine-2-thiol derivatives containing a five-membered nitrogen-containing heterocyclic fragment; ...at the same time, there are a sufficient number of examples, demonstrating the synthetic and biological potential for compounds of this kind.
The relevance of the study “structure – acute toxicity” relationship in a number of newly synthesized derivatives of 1,2,4-triazole-3(2H)-thione with pyrimidine-2-thiol is due to the synthesis of potential low molecular weight interferon inducers and antitumor agents, the search for molecular descriptors of their structure, important for establishing “structure – acute toxicity” laws, as a system for evaluating the biological effects of compounds. Therefore, it is strategically and economically justified to conduct a study of the acute toxicity of synthesized compounds as a priority.
The aim of the work is targeted synthesis of a number of S-derivatives (1,2,4-triazole-3(2H)-yl)methyl)thiopyrimidines and the establishment of the “structure – acute toxicity” relationship.
Materials and methods. A modern set of physical-chemical research methods was used to study the compounds. The study of the acute toxicity of the synthesized compounds was performed on adult Danio rerio. During the experiments, the fish were kept on a diet for a test period of 96 hours, and their mortality was checked every 24, 48, 72 and 96 hours with the test compounds in each mini-aquarium containing at least 7 individuals of Danio rerio.
Results. Results 1H NMR spectra confirm that the alkylation reaction occurs specifically on the sulfur atom. Thus, after analyzing LC50 data, we found that the least toxic among the studied compounds is 2-(((4-methyl-5-(octylthio)-4H-1,2,4-triazole-3-yl )methyl)thio)pyrimidine with an acute toxicity value of 49.66 mg/l. The most toxic compound is 2-(((4-methyl-5-(methylthio)-4H-1,2,4-triazole-3-yl)methyl)thio)pyrimidine with an LC50 value of 8.29 mg/l. The low toxicity of the compound 2-(((4-methyl-5-(octylthio)-4H-1,2,4-triazole-3-yl)methyl)thio)pyrimidine is most likely due to the presence of an octyl substituent, which sufficiently penetrates through biological membranes and does not have a strong toxic effect on organ systems. Furthermore, it does not accumulate but is metabolized in the cell.
Conclusions. New hybrids of 1,2,4-triazole-3(2H)-yl)methyl)thiopyrimidines were obtained using the heterocyclization reaction of the intermediate carbothioamide. To reduce the indicators of acute toxicity and increase their biological activity, synthesized S-derivatives of this series were created. It was established that S-derivatives of 1,2,4-triazole-3(2H)-yl)methyl)thiopyrimidines belong to moderately toxic to low-toxic compounds according to the classification of D. R. Passino. 2-(((4-Methyl-5-(octylthio)-4H-1,2,4-triazole-3-yl)methyl)thio)pyrimidine has an acute toxicity value of 49.66 mg/l. The most toxic compound is 2-(((4-methyl-5-(methylthio)-4H-1,2,4-triazole-3-yl)methyl)thio)pyrimidine with an LC50 value of 8.29 mg/l.
A contact mechanics model is developed which takes into account possible phase transformations in materials induced by hydrostatic and shear stresses associated with indentation. The proposed model ...allows prediction of the average thickness and approximate shape of the phase transformation zone in semiconductors and ceramics under various types of diamond indenters. The results of theoretical calculation are in good agreement with the available experimental data.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Silicon and gallium arsenide indentations have been investigated by using Raman spectroscopy. This perfect tool permits the study of the strain field within and around the indentation with ...3D-micrometric resolution. By mapping both indented materials, we show that the strain varies strongly in GaAs and is constant in Si within indentations. With the selected orientation of GaAs, the two observed phonons provide a way to determine the local symmetry of the strain in all the area of the fingerprint. In Si, the quite constant value within the indentation, always reported in the literature with low laser power, seems to be correlated with the metastable phases created. To provide evidence for this fact, we have selected samples which favour metastable phases over amorphous, allowing the study of the correlation of the Raman peaks associated with metastable crystalline Si phases (Si-XII) and associated with diamond Si-I. The frequency shift plot of the 355 cm-1 band as a function of the Si-I Raman band frequency at 522 cm-1 exhibits a negative slope. The strains in both phases have an opposite sign. This accurate observation provides an insight into the origin of the surprising high strain in silicon.
A molecular-genetic analysis of the nucleotide sequences of the cytochrome
b
gene (1140 base pairs) of the mitochondrial DNA and 17 microsatellite loci of eight samples of roe deer from the Samara ...forest of Dnipropetrovsk oblast (Ukraine) was carried out. For comparison, 212 corresponding mtDNA sequences of the Siberian and European roe deer and data on the variability of microsatellite markers in 49 representatives of these species were included in the study. It was noted that all the analyzed mitochondrial sequences of individuals from the Samara forest are characteristic of the Siberian roe
Capreolus pygargus
Pallas, 1771. Four haplotypes were described, all of which belonged to the haplogroup typical for the western part of the range of
C. pygargus
. A fragment analysis of the microsatellite loci of nuclear DNA confirmed the identification of the investigated group with the Siberian species.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The correlations between structures and mechanical characteristics of α-AlB12-, AlB12C2-, B4C-based lightweight ceramics and composites synthesized or sintered by hot pressing (at 30 MPa) and ...SiC-based ceramics obtained by reactive sintering are compared. The effect of C, TiC and SiC additions on the properties of the resultant composites and the particularities of the ceramics destruction under shock loading are discussed. Ballistic tests performed on 10 mm thick plates fabricated from the developed ceramics (2.63 g/cm3 density; 78 wt% B4C and 22 wt% SiC composition according to X-ray diffraction analysis; B3.64CSi0.01 and SiC1.07 stoichiometry according to SEM microprobe X-ray analysis), showed that the material could withstand a 10 m distance shot using a bullet with initial kinetic energy of 3.7 kJ.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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