Noble gases in presolar diamonds III: Implications of ion implantation experiments with synthetic nanodiamonds

A series of experiments carried out by Koscheev et al. (1998, 2001, 2004, 2005) showed that the bimodal release of heavy noble gases from meteoritic nanodiamonds can be reproduced by a single implanted component. This paper investigates the implications of this result for interpreting the noble gas compositions of meteoritic nanodiamonds and for their origin and history. If the bimodal release exhibited by meteorite diamonds reflects release of the P3 noble gas component, then the composition inferred for the pure Xe-HL end member changes slightly, the excesses of heavy krypton isotopes that define Kr-H become less extreme, evidence appears for a Kr-L component, and the nucleosynthetic contribution to argon becomes much smaller. After correction for cosmogenic neon inherited from the host meteorites, the neon in presolar diamonds shows evidence for pre-irradiation, perhaps in interstellar space, and a nucleosynthetic component perhaps consistent with a supernova source. After a similar correction, helium also shows evidence for presolar irradiation and/or a nucleosynthetic component. For the case of presolar irradiation, due to the small size of the diamonds, a large entity must have been irradiated and recoiling product nuclei collected by the nanodiamonds. The high 3He/21Ne ratio (~43) calls for a target with a (C + O)/heavier-element ratio higher than in chondritic abundances. Bulk gas + dust (cosmic abundances) meet this criteria, as would solids enriched in carbonaceous material. The long recoil range of cosmogenic 3He argues against a specific phase. The excess 3He in presolar diamonds may represent trapped cosmic rays rather than cosmogenic 3He produced in the vicinity of the diamond crystals.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

EPIDEMIOLOGICAL STUDY OF MAIN CLONES DISTRIBUTION GENOTYPE BEIJING OF MYCOBACTERIUM TUBERCULOSIS WITHIN IRKUTSK REGION

Aim. To estimate the dynamics changes in the population structure of the tuberculosis (ТВ) pathogen in the Irkutsk region by comparison of genotypes of M. tuberculosis from patients of different age groups. Materials and methods. 588 epidemiologically unrelated strains of M. tuberculosis isolates from 567 ТВ patients were characterized using 24-locus MIRU-VNTR typing. 160 strains belonged to patients of different age groups. 59 strains were isolated from the «young» people with ТВ who were bom after 1990 and 101 isolates from people who were born before 1955. Results. Two-thirds of the samples (427/567) were genotype Beijing with the dominance of two subtypes belonging to the modem epidemic clonal complexes CC1 and CC2. The high level of clustering profiles of CC1 and CC2 genotype Beijing in «older» and «young» patients in the Irkutsk region indicates the presence and active transmission of epidemic CC1 and CC2 subtypes over the past fifty years

Heterogeneity of the interstellar diamond in the CV3 meteorite efremovka

Based on the heterogeneity in the contents and isotopic compositions of carbon, nitrogen, and rare gases found in different (in grain size) interstellar diamond fractions of the meteorite Efremovka, we discuss issues associated with the nature of the diamond, the distribution of the isotopic components of impurity chemical elements in it, and the kinetics of their release