403 research outputs found

    A theoretical study of the structural phases of Group 5B - 6B metals and their transport properties

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    In order to predict the stable and metastable phases of the bcc metals in the block of the Periodic Table defined by groups 5B to 6B and periods 4 to 6, as well as the structure dependence of their transport properties, we have performed full potential computations of the total energies per unit cell as a function of the c/a ratio at constant experimental volume. In all cases, a metastable body centered tetragonal (bct) phase was predicted from the calculations. The total energy differences between the calculated stable and metastable phases ranged from 0.09 eV/cell (vanadium) to 0.39 eV/cell (tungsten). The trends in resistivity as a function of structure and atomic number are discussed in terms of a model of electron transport in metals. Theoretical calculations of the electrical resistivity and other transport properties show that bct phases derived from group 5B elements are more conductive than the corresponding bcc phases, while bct phases formed from group 6B elements are less conductive than the corresponding bcc phases. Special attention is paid to the phases of tantalum where we show that the frequently observed beta phase is not a simple tetragonal distortion of bcc tantalum

    Structure and Peculiarities of a Clinical Course of Tick-Borne Infections in Children of the Irkutsk Region

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    At present there are few studies generalizing the clinical picture of infections, transmitted by Ixodid ticks, in children population. Tick-borne viral encephalitis is still one of the important natural focal infections and accounts for up to 27 % among other tick-borne infections.The aim of the study was to determine the structure and features of the clinical course of tick infections in children of the Irkutsk region.Materials and methods. We conducted a retrospective analysis of 58 cases over three-year period from 2015 to 2017 of children aged 1 to 18 years diagnosed with tick-borne viral encephalitis (TVE), ixodid tick-borne borreliosis (ITB), tick-borne rickettsiosis (TR) according to the data of Irkutsk Regional Infectious Clinical Hospital.Results and discussion. Among tick-borne infections, TVE was found in 43 % of cases, ITB – in 27.5 %, TR – in 29.5 %, there was one case of mixed infection: TVE + tick-borne typhus in North Asia. In TVE, feverish form was found in 40 % of cases, meningeal form – in 36 %, meningoencephalitic form – in 20 %, polyradiculonevritic form – in 4 %. Medium severity was observed in 56 % of cases, severe – in 28 %. In ITB, non-erythematous form was revealed in 62.5 % of cases, erythematous – in 12.5 %. Clinical and epidemiological TR was registered in 18 % of cases. In patients with TVE recovery was observed in 84 %, however, there were 4 % of neurological complications. With the diagnosis of ITB and TR, almost all children were discharged in a satisfactory condition. No deaths were reported within 3 years. According to the medical history: only 1 child was vaccinated against TVE, 2 children underwent seroprevention; ticks, who bit 4 patients, were studied. Medical history showed that 57 % of children had tick bites, and 7 % of cases associated the disease with consumption of non-boiled goat or cow milk. Residents of Irkutsk, Angarsk and Shelekhov comprised 47 %, residents of the Irkutsk region – 53 %. The most common localization of bites is the head and neck.Conclusion. There is a low public commitment to the vaccine prevention of tick-borne infections. Therefore, it is necessary to promote both specific and non-specific prevention of tick-borne encephalitis among children of the Irkutsk region

    Bioluminescent System of Luminous Bacteria for Detection of Microbial Contamination

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    Microbial contamination is usually analyzed using luciferin-luciferase system of fireflies by the detection of adenosine-5’-triphosphate (ATP). There is an opportunity to assess the bacterial contamination of various objects based on a quantitative analysis of other nucleotides. In the present study, a bioluminescent enzyme system of luminous bacteria NADH:FMN-oxidoreductase (Red) and luciferase (BLuc) was investigated to understand if it can be used for quantitative measurements of bacterial cells by nicotinamide adenine dinucleotide (NADH) and flavin mononucleotide (FMN) detection. To increase the sensitivity of bioluminescent system to FMN and NADH, optimization of assay conditions was performed by varying enzymes and substrates concentrations. The lowest limits of detection were 1.2 nM FMN and 0.1 pM NADH. Escherichia coli cells were used as a model bacterial sample. FMN and NADH extraction was made by destructing cell membrane by ultrasonication. Cell suspension was added into the reaction mixture instead of FMN and NADH, and light intensity depended on number of bacterial cells in the reaction mixture. Centrifugation of sonicated sample as an additional step of sample preparation did not improve the sensitivity of method. The experimental results showed that Red and BLuc system could detect at least 800 thousand bacterial cells mL-1 by determining concentration of NADH extracted from lysed cells, while 3.9 million cells mL-1 can be detected by determining concentration of FM

    Surface Properties of the Half- and Full-Heusler Alloys

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    Using a full-potential \textit{ab-initio} technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys, NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co2_2MnGe, Co2_2MnSi and Co2_2CrAl. The MnSb terminated surfaces of the half-Heusler compounds present properties similar to the bulk compounds and, although the half-metallicity is lost, an important spin-polarisation at the Fermi level. In contrast to this the Ni terminated surface shows an almost zero net spin-polarisation. While the bulk Co2_2MnGe and Co2_2MnSi are almost half-ferromagnetic, their surfaces lose the half-metallic character and the net spin-polarisation at the Fermi level is close to zero. Contrary to these compounds the CrAl terminated (001) surface of Co2_2CrAl shows a spin polarisation of about 84%.Comment: 14 pages, 6 figure

    Biosynthesis of the Bacillus intermedius subtilisin-like serine proteinase by the recombinant Bacillus subtilis strain

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    The effect of certain nutrients on the growth and production of the Bacillus intermedius subtilisin-like serine proteinase by the recombinant strain Bacillus subtilis AJ73(pCS9) was studied. Glucose was found to inhibit the synthesis of proteinase in the early (28 h of growth) but not in the late stationary phase (48 h of growth). The inhibitory effect of the other mono- and disaccharides studied was less pronounced. Casamino acids added to the medium at concentrations of 0.1-1% as an additional carbon and nitrogen source stimulated enzyme biosynthesis. Individual amino acids (cysteine, asparagine, glutamine, tryptophan, histidine, and glutamate) also stimulated enzyme biosynthesis in the early stationary phase by 25-30%, whereas other amino acids (valine, leucine, alanine, and aspartate) were ineffective or even slightly inhibitory to enzyme production. The stimulatory effect of the first group of amino acids on the synthesis of proteinase in the late stationary phase was negligible. In contrast, the bivalent ions Ca2+, Mg2+, and Mn 2+ stimulated biosynthesis of proteinase in the late stationary phase (by 20-60%) and not in the early stationary phase. The data indicate that there are differences in the biosyntheses of proteinase by the recombinant B. subtilis strain during the early and late periods of the stationary phases. © Pleiades Publishing, Inc., 2006

    Growth conditions and production of the Bacillus intermedius subtilisin-like serine proteinase by the recombinant Bacillus subtilis strain

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    The effect of the components of the nutrient medium on growth and production of the Bacillus intermedius subtilisin-like serine proteinase by the recombinant strain Bacillus subtilis AJ73(pCS9) was studied. The production of proteinase was found to be dependent on the composition of the nutrient medium and showed two peaks, at the 28th and 48th h of growth. The concentrations of the main components of the nutrient medium (peptone and inorganic phosphate) optimal for the biosynthesis of subtilisin-like serine proteinase at the 28th and 48th h of growth were determined in factorial experiments. Complex organic substances, casein at concentrations of 0.5-1%, gelatin at concentrations of 0.5-1%, and yeast extract at a concentration of 0.5%, stimulated the production of subtilisin-like serine proteinase by the recombinant strain. The study of the sporulation dynamics in this strain showed that the proteinase peaks at the 28th and 48th h of growth correspond, respectively, to the initial stage of sporulation and to the terminal stages of endospore formation (V-VII stages of sporulation). © Pleiades Publishing, Inc., 2006

    L.L. Fofanof: 140th anniversary of his birth. Contribution to science

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    The article is dedicated to Professor L.L. Fofanof’s scientific activity. He headed the faculty therapeutic clinic of Kazan Imperial University in 1915-1920. Being a student L.L. Fofanov was interested in pathological anatomy and physiology. His dissertation «To physiology of n. depressoris» was dedicated to studying the vasomotor center. During his visit in Germany he worked a lot. In Charite together with Professor His he studied gout and its treatment with Radium emanation. In Halle clinic under Professor Schmidt’s supervision he studied assimilation of starch in normal and pathological digestion. L.L. Fofanov also made a contribution to tuberculosis treatment: with professor V.F. Orlovskiy he studied treatment of tuberculosis with simulated pneumothorax. In his research professor L.L. Fofanov paid great attention to the issues of pathogenesis and pathogenetic substantiation of the clinical manifestation and treatment. During the World War I and Civil War he fought against typhus epidemies: he saw patients, gave lectures, studied the features of myocardial involvement. He died in 1920 from typhus

    Taphonomic phenomenon of ancient hair from Glacial Beringia:perspectives for palaeoecological reconstructions

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    An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post-mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750 +/- 50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115 +/- 40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3-1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrostpreserved hair is a unique repository of Ice Age organisms.</p

    Association of the AGT, ACE, NOS3 polymorphism with subclinical arterial wall changes and cardiovascular diseases risk factors

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    Background. Renin-Angiotensin-Aldosterone System activation (RAAS) and nitric oxide (NO) reduction lead to the changes in the arterial wall, which, in turn, create a favourable environment for the development of cardiovascular diseases (CVD). There is only limited knowledge of the influence of proteins participating in the RAAS activation and providing NO bioavailability on the parameters of the arterial wall state (pulse wave velocity (PWV), carotid artery intima-media thickness (cIMT), endothelium-dependent vasodilation (EDVD), presence of atherosclerotic plaques) and risk factors of CVD. Aim. Finding the association between the AGT, ACE, NOS3 polymorphism and PWV, cIMT, EDV, presence of atherosclerotic plaques and risk factors of CVD in healthy subjects. Methods. Using intergroup analysis and models of multiple logistic regression, we examined the association of AGT с.521СТ polymorphism, AСE InsDel polymorphism, NOS3 с.894GT polymorphism with arterial wall changes and risk factors of CVD in 160 healthy people of different ages. Results. The CT genotype of AGT с.521СТ polymorphism was associated with lower levels of systolic blood pressure (BP) (p=0.013) and central systolic BP (p=0.029), higher level of Insulin-Like Growth Factor (IGF) (p=0.027). The DD genotype of ACE InsDel polymorphism was associated with a higher waist/hip ratio (p=0.044), lower level of high density lipoprotein cholesterol (p=0.01), lower index of EDVD (p=0.042), higher incidence ofendothelial dysfunction (ED) (p=0.026). The GG genotype of NOS3 с.894GT polymorphism was associated with higher levels of central systolic BP (p=0.022) and central mean BP (p=0.033), total cholesterol (p=0.025), low density lipoprotein cholesterol (p=0.014) and IGF (p=0.042), higher incidence of ED (p=0.007), albuminuria (p=0.032) and insulin resistance (p=0.03). Conclusion. We have found the association of the AСE and NOS3 polymorphism with endothelial dysfunction and the metabolic status

    RNA CoSSMos: Characterization of Secondary Structure Motifs—a searchable database of secondary structure motifs in RNA three-dimensional structures

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    RNA secondary structure is important for designing therapeutics, understanding protein–RNA binding and predicting tertiary structure of RNA. Several databases and downloadable programs exist that specialize in the three-dimensional (3D) structure of RNA, but none focus specifically on secondary structural motifs such as internal, bulge and hairpin loops. The RNA Characterization of Secondary Structure Motifs (RNA CoSSMos) database is a freely accessible and searchable online database and website of 3D characteristics of secondary structure motifs. To create the RNA CoSSMos database, 2156 Protein Data Bank (PDB) files were searched for internal, bulge and hairpin loops, and each loop's structural information, including sugar pucker, glycosidic linkage, hydrogen bonding patterns and stacking interactions, was included in the database. False positives were defined, identified and reclassified or omitted from the database to ensure the most accurate results possible. Users can search via general PDB information, experimental parameters, sequence and specific motif and by specific structural parameters in the subquery page after the initial search. Returned results for each search can be viewed individually or a complete set can be downloaded into a spreadsheet to allow for easy comparison. The RNA CoSSMos database is automatically updated weekly and is available at http://cossmos.slu.edu
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