High prevalence of genotype B0/W148 of Mycobacterium tuberculosis among HIV-TB patients in Perm Krai and Irkutsk Region

Background. The population with HIV-infection plays significant role in ongoing tuberculosis pandemic. Immunosuppression due to HIV-infection is one of the causes of TB disseminated forms in this group of people. Having low immune status is also often associated with a polyclonal M. tuberculosis infection. Aim of the research: comparative assessment of epidemic genotypes of M. tuberculosis prevalence and mixed genotypes identification within HlV-TB co-infected patients in two Russian regions. Materials and methods. The DNAs of 78 clinical isolates from Irkutsk Region (IR) and 64 strains from Perm Krai (PK) have been genotyped by MIRU VNTR 24 and RD105/RD207. Strains were obtained from patients who did not have significant age and sex differences. In the PK age of the patients was 34.5 ± 0.9, in IR - 34.4 ± 1.5 years. The samples were obtained from 67.2 and 65.4 % of men, respectively. Result. The study of the M. tuberculosis indicates significant predominance of Beijing genotype strains in patients with TB-HIV of PK (92.2 %) compared to the IR (59.5 %) (х2 = 18.0; p < 0.01). The prevalence of MDR pathogens in TB-HIV patients exceeded 50 %. The mixed genotype detection in the PK and IR was high (14.1 and 12.7 % respectively). The level of virulent strains B0/W148 was 34.4 % in PK patients and 25.3 % in IR ones. Analysis of the results suggests the epidemic spread of MDR-TB in the immunocompromised individuals. Conclusions: The identified trends may indicate that Perm Kray have a process of active dissemination of transmissible strains of M. tuberculosis within HIV-infected population

Optically Active Si:Er Layers Grown by the Sublimation MBE Method

We report the first application of sublimation molecular beam epitaxy to grow uniformly and selectively doped Si:Er layers with Er concentration up to 5×10$\text{}^{18}$ cm$\text{}^{-3}$. The Hall concentration of electrons is about 10% of total Er contents. The mobility is 300-400 cm$\text{}^{2}$ V$\text{}^{-1}$ s$\text{}^{-1}$ at 300 K. All samples exhibit photoluminescence at 1.537 μm up to 100-140 K

Formation of Light Emitting Iron Disilicide/Silicon Heterostructures by Means of Pulsed Ion and Laser Beams

Abstract – Semiconducting iron disilicide (β FeSi2) is a pro mising material for the fabrication of Si based structures emitting light in the 1.5–1.6 μm telecommunication range. In this work β FeSi2/Si heterostructures were formed by high fluence implantation of n Si (100) single crystals with iron ions (Fe+) followed by treatments of the implanted Si la yers with pulsed laser or ion beams. Structural properties of the obtained heterostructures were studied by X ray diffrac tion, transmission electron microscopy and Rutherford backscattering spectrometry. It is shown that pulsed treat ment leads to the formation of nanocrystalline FeSi2 layers with a cellular structure and nearly uniform composition. On the base of β FeSi2/Si layers, light emitting in the near in frared region p+–Si/β FeSi2/n–Si/n+–Si diode structures were obtained by the implantation of low energy boron and phosphorous ions