The origin of the high velocity circumstellar gas around SN 1998S

Modelling of high resolution Balmer line profiles in the early-time spectra of SN 1998S shows that the inferred fast (roughly 400 km/s) circumstellar (CS) gas on days 23 and 42 post-explosion is confined to a narrow, negative velocity gradient shell just above the photosphere. This gas may be identified with a slow (v < 40 km/s) progenitor wind accelerated at the ejecta-wind interface. In this scenario, the photosphere coincides with a cool dense shell formed in the reverse shock. Acceleration by radiation from the supernova or by a shock-accelerated relativistic particle precursor are both possible explanations for the observed fast CS gas. An alternative, equally plausible scenario is that the fast CS gas is accelerated within shocked clouds engulfed by the outer shock, as it propagates through the intercloud wind.Comment: 9 pages, 6 figures. MNRAS, accepted. Typos added, acknowledgments correcte

Dalambert-Lagrange Principle for Mechanic Systems with One-Sided Relations.

Abstract: Dalamber-Lagrange principle expanded on to mechanics systems with one-sided relations. Ideal relations’ conditions are described. Equation of motion as Lagrange equations of first and second kinds and Hamilton equations are derived.Note: Research direction:Theoretical and applied problems of mechanic

On Unilateral Nonholonomic Constraints.

Abstract: The examples of mechanical systems with nonholonomic unilateral restrictions are considered. Impact of a disk about a rough straight line, unilateral skate, impact bilaterial skate about a straight line. Is shown, that the movement with unilateral homogeneous restrictions carries nonimpact character.Note: Research direction:Theoretical and applied problems of mechanic

Synthesis of hexahydro[1,4]diazocino[7,8,1-jk]carbazoles and 1-methoxy-9-(β-vinylethylamino)ethylcarbazoles

3-Ethylhexahydropyrazino[3,2,1-jk]carbazole is converted into hexahydro[1,4]diazocino[7,8,1-jk]carb-azoles by the action of methyl propiolate and acetylacetylene in acetonitrile and into 1-methoxy-9-(β- vinylethylamino)ethylcarbazoles by the action of acetylenedicarboxylic ester and methyl propiolate in methanol. 3-Benzyl-substituted pyrazinocarbazole does not react with alkynes. © 2012 Springer Science+Business Media, Inc

Synthesis of hexahydro[1,4]diazocino[7,8,1-jk]carbazoles and 1-methoxy-9-(β-vinylethylamino)ethylcarbazoles

3-Ethylhexahydropyrazino[3,2,1-jk]carbazole is converted into hexahydro[1,4]diazocino[7,8,1-jk]carb-azoles by the action of methyl propiolate and acetylacetylene in acetonitrile and into 1-methoxy-9-(β- vinylethylamino)ethylcarbazoles by the action of acetylenedicarboxylic ester and methyl propiolate in methanol. 3-Benzyl-substituted pyrazinocarbazole does not react with alkynes. © 2012 Springer Science+Business Media, Inc

Genomic and phenotypic analysis of siderophore-producing Rhodococcus qingshengii strain S10 isolated from an arid weathered serpentine rock environment

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. The success of members of the genus Rhodococcus in colonizing arid rocky environments is owed in part to desiccation tolerance and an ability to extract iron through the secretion and uptake of siderophores. Here, we report a comprehensive genomic and taxonomic analysis of Rhodococcus qingshengii strain S10 isolated from eathered serpentine rock at the arid Khalilovsky massif, Russia. Sequence comparisons of whole genomes and of selected marker genes clearly showed strain S10 to belong to the R. qingshengii species. Four prophage sequences within the R. qingshengii S10 genome were identified, one of which encodes for a putative siderophore-interacting protein. Among the ten non-ribosomal peptides synthase (NRPS) clusters identified in the strain S10 genome, two show high homology to those responsible for siderophore synthesis. Phenotypic analyses demonstrated that R. qingshengii S10 secretes siderophores and possesses adaptive features (tolerance of up to 8% NaCl and pH 9) that should enable survival in its native habitat within dry serpentine rock