Autoresonance in a Dissipative System

We study the autoresonant solution of Duffing's equation in the presence of dissipation. This solution is proved to be an attracting set. We evaluate the maximal amplitude of the autoresonant solution and the time of transition from autoresonant growth of the amplitude to the mode of fast oscillations. Analytical results are illustrated by numerical simulations.Comment: 22 pages, 3 figure

Effect of the regulation system of metabolic nitrogen exchange on biosynthesis of serine proteinases from Bacillus intermedius

The regulatory link between biosynthesis of Bacillus intermedius subtilisin-like serine proteinase and nitrogen metabolism in B. intermedius cells was determined. The level of the enzyme biosynthesis by the recombinant strain of Bacillus subtilis in the medium containing ammonium ions was three- to fivefold less than that in the medium with poorly utilized sodium nitrate. Accumulation of glutamyl endopeptidase in a culture liquid of this microorganism did not depend on the source of nitrogen present in the medium. During cultivation in the rich medium, the productivity of subtilisin-like proteinase in the recombinant B. subtilis strain carrying a mutation in the NrgB sensor protein was demonstrated to increase threefold compared to that of the control strain. In the minimal culture medium, mutation in the nrgB gene abolished the effect of a nitrogen source on the level of the subtilisin-like proteinase gene expression. At the same time, this mutation did not affect glutamyl endopeptidase biosynthesis. Thus, expression of the gene coding for subtilisin-like proteinase from B. intermedius is suggested to be positively regulated by the regulatory system of nitrogen metabolism. © Pleiades Publishing, Ltd., 2009

Isolation and characteristics of Bacillus intermedius glutamyl endopeptidase secreted by a recombinant strain of Bacillus subtilis at various growth phases

The recombinant strain of Bacillus subtilis bearing B. intermedius glutamyl endopeptidase gene in multicopy plasmid Δ58.21 secretes the enzyme to the medium at the phase of slowing of growth and the stationary growth phase with accumulation maxima at 24 and 48 h. Enzyme samples were isolated from the culture liquid after 24 and 48 h of culturing of and were purified up to homogeneity by ion exchange chromatography on carboxymethyl cellulose and HPLC on a MonoS column. The molecular weight of the corresponding proteins was 29 kDa. Both preparations had identical structure, but differed in affinity to the specific substrate Z-Glu-pNA. The effects of Ca2+ ions and specific low-molecular and protein inhibitors on the activity of the enzyme corresponding to various growth phases has been studied. © 2008 MAIK Nauka

Cytokine Profile of Patients with Allergic Rhinitis Caused by Pollen, Mite, and Microbial Allergen Sensitization

© 2017 Yury A. Tyurin et al. Allergic rhinitis (AR) is especially prevalent among the population of large cities. Immunologically, the airway epithelium is a region where the population of allergen-presenting cells concentrates. These cells actively express a group of receptors of the innate immune system. A specific cytokine profile is its representation. The study was aimed at evaluating the cytokine profile in patients with seasonal and perennial allergic rhinitis. The cytokine profile of nasal secretion and blood serum of 44 patients with AR was studied. 24 of them had seasonal allergic rhinitis (SAR), and 20 patients suffered from perennial allergic rhinitis (PAR). The patients' age ranged from 4 to 60 years. It was determined in our study that the activation of the GM-CSF production retained in patients with PAR sensitized to mite allergen components (Dermatophagoides pteronyssinus). There was a higher production profile of TNF-α and TSLP in nasal secretion in the patients with perennial allergic rhinitis and additional high sensitization to SEs. Sensitization to mold fungal allergen components significantly increases in patients with seasonal allergic rhinitis. They demonstrated high level of sensitization to the Aspergillus fumigatus component m3. Thus, along with other clinical trials, the study performed would clarify some aspects of molecular pathogenesis of human allergic rhinitis

Isolation and characterisation of Bacillus amyloliquefaciens H2 glutamyl endopeptidase that is secreted in stationary phase of culture growth

The culture broth of Bacillus amyloliquefaciens H2 was used for isolation by chromatography on CM-cellulose and MonoS columns of proteinase that are secreted in early and late stationary phases of culture growth. Based on their inhibition by specific serine proteinase inhibitors and their action on specific chromogenic substrates and on oxidised B-chain of insulin, the enzymes were classified as glutamyl endopeptidases. The molecular weight of secreted enzyme is 26.5 kDa. We show that although the enzyme is secreted in different phases of culture growth, both enzyme fractions have similar enzymatic properties and amino acid content, but they were distinguished in

Conformational stability of diastereomeric 8,8-dichloro-3,5-dioxa-4-thia-4-oxobicyclo[5.1.0]octanes: X-ray crystallography, dynamic 1H and 13C NMR spectroscopy study

X-ray data for both title molecules display a chair conformation with exo location of cyclopropane moiety and axial or equatorial sulfinyl group. Dynamic 1H and 13C NMR spectroscopy at -95 °S{cyrillic} exhibit conformational homogeneity for the first diastereomer and two component chair - twist-boat equilibrium (2:3) for the latter. © 2007 Elsevier B.V. All rights reserved

Stereochemistry of seven-membered heterocycles: XLVI. Synthesis and dynamic 13C NMR spectroscopy of spiro[cyclohexane-1,4′-[3,5] dioxabicyclo[5.1.0]octanes]. DFT calculations of structurally related formaldehyde and acetone acetals

Spiro[cyclohexane-1,4′-[3,5]dioxabicyclo[5.1.0]octanes] were synthesized, and their conformational behavior was studied by dynamic 13C NMR spectroscopy. Anancomeric displacement of conformational equilibrium toward two nonequivalent twist conformers with close energies was revealed. The relative Gibbs energies ΔG o and enthalpies of formation ΔH o of twist and chair-like conformers with endo and exo orientation of the three-membered ring of structurally related formaldehyde and acetone acetals were calculated in terms of the density functional theory at the B3LYP/6-31G(d,p) level. Like spiro-cyclohexane analogs, they were shown to have a non-chair conformation. © 2007 Pleiades Publishing, Ltd

Spatial structures of tripeptides glycylglycyl-l-histidine and glycylglycyl-l-tyrosine based on residual dipolar couplings and quantum-chemical computations

A novel approach to the determination of the spatial structure of oligopeptides on the basis of an analysis of the residual dipolar couplings 1H-13C assisted by quantum-chemical computations with considering solvent effects is proposed to characterize the conformations of the tripeptides GlyGlyHis and GlyGlyTyr with significant folding of the latter to left-handed helix. © 2011 Mendeleev Communications. All rights reserved

Numerical simulation of the flow in the boiler air intake

The article presents the results of numerical simulation of the flow in a complex region - an element of the air intake of a wall-mounted boiler. There are very few studies of this kind, and the geometry of the computational domain is rather specific. For this reason, the results obtained are difficult to compare in order to unequivocally speak about validity, in addition, different models lead to somewhat different results. Nevertheless, one can say about the formation of a significant vortex zone, which results in a much higher resistance at the entrance than for a conventional elbow with the same sizes.В статье приводятся результаты численного моделирования течения в сложной области – элементе воздушного тракта настенного котла. Исследований такого рода очень мало, а геометрия расчетной области довольно специфична. По этой причине полученные результаты сложно сравнить, чтобы однозначно говорить о валидности, кроме того разные модели приводят к несколько разным результатам. Тем не менее, можно говорить, об образовании значительной вихревой зоны, что приводит к существенно более высокому сопротивлению при входе, чем для обычного поворота при таких же соотношениях размеров