Electron-electron interaction in carbon nanostructures

The electron-electron interaction in carbon nanostructures was studied. A new method which allows to determine the electron-electron interaction constant $\lambda_c$ from the analysis of quantum correction to the magnetic susceptibility and the magnetoresistance was developed. Three types of carbon materials: arc-produced multiwalled carbon nanotubes (arc-MWNTs), CVD-produced catalytic multiwalled carbon nanotubes (c-MWNTs) and pyrolytic carbon were used for investigation. We found that $\lambda_c$=0.2 for arc-MWNTs (before and after bromination treatment); $\lambda_c$ = 0.1 for pyrolytic graphite; $\lambda_c >$ 0 for c-MWNTs. We conclude that the curvature of graphene layers in carbon nanostructures leads to the increase of the electron-electron interaction constant $\lambda_c$.Comment: 12 pages, 18 figures, to be published in the Proceedings of the NATO Advanced Research Workshop on Electron Correlation in New Materials and Nanosystems, NATO Science Series II, Springer, 200

ANTIOXIDANT EFFECTOF NUCLEINAT SODIUM IN PATIENTS WITH CHRONIC KIDNEYDISEASE І–II STAGES: UNCOMPLICATED PYELONEPHRITIS

Objective: to determine the antioxidant effects of Nucleinat sodium in patients with uncomplicated recurrent pyelonephritis. Material and methods. We have analyzed the indicators of oxidant/ antioxidant (O/ A) balance in the blood of 55 patients with uncomplicated recurrent pyelonephritis. Women were randomized into 2 groups: I (n=30) consisted of patients treated with Nucleinat sodium at a dose of 0.25 mg 4 times daily for 14 days to II (n=25) included patients who used only antibacterial therapy (according to the set sensitivity identified pathogens). The control group consisted of 20 conditional healthy donors, matched for sex and age. Results. In the blood ofpatients prior to treatment were observed reduction of total peroxidase activity of red blood cells (p<0.0001), ceruloplasmin (p=0,03), SH–groups (p=0.001) and increase in serum MDA, and oxidative stress index (p<0.0001) compared with the conditionally healthy donors. Comprehensive treatment with Nucleinat sodium statistically significantly led to normalization of these parameters and decrease of urine N–acetyl–p–D– glucosaminidase and p–galactosidase (p<0,001 and p=0.04, respectively). Conclusions. For the treatment of uncomplicated recurrent pyelonephritis appropriate to apply Nucleinat sodium at a dose of 0.25 mg 4 times / day, which helps to reduce the activity of oxidative processes and the negative impact of oxidative stress on the patient, and increases of antioxidant protection

Model for initiation of quality factor degradation at high accelerating fields in superconducting radio-frequency cavities

A model for the onset of the reduction in SRF cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Breakdown of the surface barrier against magnetic flux penetration at the cavity equator is considered to be the critical event that determines the onset of Q-drop. The worst case of triangular grooves with low field of first flux penetration Hp, as analyzed previously by Buzdin and Daumens, [1998 Physica C 294: 257], was adapted. This approach incorporates both the geometry of the groove and local contamination via the Ginzburg-Landau parameter kappa, so the proposed model allows new comparisons of one effect in relation to the other. The model predicts equivalent reduction of Hp when either roughness or contamination were varied alone, so smooth but dirty surfaces limit cavity performance about as much as rough but clean surfaces do. When in combination, contamination exacerbates the negative effects of roughness and vice-versa. To test the model with actual data, coupons were prepared by buffered chemical polishing and electropolishing, and stylus profilometry was used to obtain distributions of angles. From these data, curves for surface resistance generated by simple flux flow as a function of magnetic field were generated by integrating over the distribution of angles for reasonable values of kappa. This showed that combined effects of roughness and contamination indeed reduce the Q-drop onset field by ~30%, and that that contamination contributes to Q-drop as much as roughness. The latter point may be overlooked by SRF cavity research, since access to the cavity interior by spectroscopy tools is very difficult, whereas optical images have become commonplace. The model was extended to fit cavity test data, which indicated that reduction of the superconducting gap by contaminants may also play a role in Q-drop.Comment: 15 pages with 7 figure

Multiple intrasyntenic rearrangements and rapid speciation in voles

Abstract Remarkably stable genomic chromosome elements (evolutionary conserved segments or syntenies) are the basis of large-scale chromosome architecture in vertebrate species. However, these syntenic elements harbour evolutionary important changes through intrachromosomal rearrangements such as inversions and centromere repositioning. Here, using FISH with a set of 20 region-specific probes on a wide array of 28 species, we analyzed evolution of three conserved syntenic regions of the Arvicolinae ancestral karyotype. Inside these syntenies we uncovered multiple, previously cryptic intrachromosomal rearrangements. Although in each of the three conserved blocks we found inversions and centromere repositions, the blocks experienced different types of rearrangements. In two syntenies centromere repositioning predominated, while in the third region, paracentric inversions were more frequent, whereas pericentric inversions were not detected. We found that some of the intrachromosomal rearrangements, mainly paracentric inversions, were synapomorphic for whole arvicoline genera or tribes: genera Alexandromys and Microtus, tribes Ellobini and Myodini. We hypothesize that intrachromosomal rearrangements within conserved syntenic blocks are a major evolutionary force modulating genome architecture in species-rich and rapidly-evolving rodent taxa. Inversions and centromere repositioning may impact speciation and provide a potential link between genome evolution, speciation, and biogeography

Influence of the atomic-wall collision elasticity on the coherent population trapping resonance shape

We studied theoretically a coherent population trapping resonance formation in cylindrical cell without buffer gas irradiated by a narrow laser beam. We take into account non-zero probabilities of elastic ("specular") and inelastic ("sticking") collision between the atom and the cell wall. We have developed a theoretical model based on averaging over the random Ramsey pulse sequences of times that atom spent in and out of the beam. It is shown that the shape of coherent population trapping resonance line depends on the probability of elastic collision.Comment: 18 pages, 5 figure

FEATURES OF THE MICROBIAL SPECTRUM UROGENITAL SYSTEM OF WOMEN WITH RECURRENT PYELONEPHRITIS

The aim of our research was to identify the peculiarities of the microbial spectrum urogenital system of the women with recurrent pyelonephritis. Materials and methods. We have conducted a comprehensive micro-biological examination different biological material (urine, vaginal swabs, scraping of urethral and cervical canal’s) of 175 women with recurrent pyelonephritis. The patients were divided in accordance with frequency of recurrent. The microbial spectrum urogenital system of 98 women with recurrent pyelonephritis (group 1) was compared with 77 women with sporadic pyelonephritis (up to 2 times per year) (group 2). The research included the process of identification of bacterial agents, mollicutes, chlamydia as well as yeasts. Results. In the women with recurrent pyelonephritis had the significant increase of frequency of identification of E. faecalis in urine (p=0.03), in urethral canal (p=0.05), and vaginal scraping (p=0.02). 48 women from 1st group had bacterial mix-infection. At the same time, the women from comparative group had only in 25 (32.6%) cases (p=0.027). The direct associative relationship was found between existence of S. epidermidis in urethral canal, in cervical canal, in vagina and the frequency of recurrent pyelonephritis (ρ=0.2, р=0.009; ρ=0.23, р=0.004 and ρ=0.19, р=0.01 respectively); E. faecalis in the urethral canal (ρ=0.19, р=0.02); Candida albicans in the vagina (ρ=0.17, р=0.03). 79.6% examined patients were infected by mollicutes, viruses and chlamydia. Conclusions. Consistent high level of urethral’s and vaginal’s bacterial weight of the women with recurrent pyelonephritis leads to the migration of causative agents into bladder and to activates formation of recurrent of the disease. Identified peculiarities of microbial spectrum prove the necessity mandatory micro-biological research not only urine, but urethra, cervical canal, and vagina