Bulk Nanocrystalline Thermoelectrics Based on Bi-Sb-Te Solid Solution

A nanopowder from p-Bi-Sb-Te with particles ~ 10 nm were fabricated by the ball milling using different technological modes. Cold and hot pressing at different conditions and also SPS process were used for consolidation of the powder into a bulk nanostructure and nanocomposites. The main factors allowing slowing-down of the growth of nanograins as a result of recrystallization are the reduction of the temperature and of the duration of the pressing, the increase of the pressure, as well as addition of small value additives (like MoS2, thermally expanded graphite or fullerenes). It was reached the thermoelectric figure of merit ZT=1.22 (at 360 K) in the bulk nanostructure Bi0,4Sb1,6Te3 fabricated by SPS method. Some mechanisms of the improvement of the thermoelectric efficiency in bulk nanocrystalline semiconductors based on BixSb2-xTe3 are studied theoretically. The reduction of nanograin size can lead to improvement of the thermoelectric figure of merit. The theoretical dependence of the electric and heat conductivities and the thermoelectric power as the function of nanograins size in BixSb2-xTe3 bulk nanostructure are quite accurately correlates with the experimental data.Comment: 35 pages, 24 figures, 4 tables, 52 reference

Photometric observations of the supernova 2009nr

We present the results of our UBVRI CCD photometry for the second brightest supernova of 2009, SN 2009nr, discovered during a sky survey with the telescopes of the MASTER robotic network. Its light and color curves and bolometric light curves have been constructed. The light-curve parameters and the maximum luminosity have been determined. SN 2009nr is shown to be similar in light-curve shape and maximum luminosity to SN 1991T, which is the prototype of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded far from the center of the spiral galaxy UGC 8255 and most likely belongs to its old halo population. We hypothesize that this explosion is a consequence of the merger of white dwarfs

Combined Surgical Tactics with Step-up Approach in the Treatment of Infected Acute Pancreatitis

Objective. To evaluate the results of treatment using minimally invasive interventions and open necrectomy in patients with infected acute pancreatitis. Materials and methods. A retrospective cohort two-centered analysis was performed in 211 patients with infected acute pancreatitis who divided into two groups: the first included 101 patients, in the treatment of which used open surgery; the second included 110 patients, in the treatment of which used treatment tactic step-up approach. Results. In the first group used open necrosectomy with drainage for postoperative lavage (75 patients, 74.3%), including open packing with planned re-laparotomy (8 patients, 7.9%), and omentobursostomy for necrosectomy after surgery (18 patients, 17.8%). Postoperative complications occurred in 58 (57.4%), after the surgery 34 (33.7%) patients was died: 30 had a thirty-day mortality, and 4 had a ninety-day mortality. In the second group group, 72 (65.5%) patients were treated by percutaneous catheter drainage, 6 (5.5%) by video-assisted retroperitoneal debridement and drainage, 5 (4.5%) by through the wall of the stomach or duodenum in the infected pseudocyst and open necrosectomy was performed on 27 (24.5%) patients. Postoperative complications occurred in 37 (33.6%) patients, after the surgery 19 (17.3%) was died: 15 had a thirty -day mortality and 4 had a ninety-day mortality. In the regression analysis, only the presence of multiple organ dysfunction before (AUC = 0.867) and after surgery (AUC = 0.930) significantly affected postoperative mortality, but the effect of the prevalence of pancreatic necrosis (AUC = 0.693) on mortality was limited. Differences were likely between groups (χ2=7.282, p=0.026). Conclusion. The surgical treatment should be initiated with a minimally invasive procedures and combination these operations with open surgery was able to reduce complications and mortality in the patients with infected acute pancreatitis

Optical polarization observations with the MASTER robotic net

We present results of optical polarization observations performed with the MASTER robotic net for three types of objects: gamma-ray bursts, supernovae, and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16$^m$). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.Comment: 31 pages, 12 figures, 4 tables; Exposure times in Table 2 have been correcte

High thiamine dose restores levels of specific astroglial proteins in rat brain astrocytes affected by chronic ethanol consumption

Long-term ethyl alcohol consumption induces a deficiency of essential nutrient thiamine (vitamin B1 ) and profoundly impairs metabolic processes in nervous tissue, resulting in structural and functional alterations in the central nervous system (CNS). This study was performed to evaluate protective effects of thiamine acute dose on the level of glial fibrillary acidic protein (GFAP), a sensitive marker of astroglia, and B1-related enzyme thiamine pyrophosphokinase (TPK) activity in brain of rats chronically exposed to ethanol. The rats were divided into three groups as follows: i) control group; ii) rats given 15% ethanol solution as drinking water for 9 months (EtOH group), iii) EtOH rats given thiamine per os in a dose of 2.0 mg/kg one day before experiment termination (n = 4 in each group). GFAP levels were analyzed in cerebellum, brain cortex and hippocampus by western blot and immunohistochemistry. Brain TPK activity was measured with the use of the yeast apopyruvate decarboxylase apoenzyme (apoPDC). Thiamine concentration in liver was estimated with the use of thiochrome method. It was demonstrated that GFAP content was dramatically reduced in all studied brain regions of EtOH-exposed rats (approximately by 60%, P < 0.05) compared with control rats indica­ting profound astroglial dysfunction. Thiamine treatment was shown to recover GFAP levels up to 80% vs. control value in the brain of EtOH-exposed rats (P < 0.05). Ethanol consumption resulted in 3.7-fold decrease in liver thiamine content and 1.4-fold decrease in brain TPK activity, as compared with control (P < 0.05). Thiamine treatment of EtOH-exposed rats significantly elevated B1 liver level, however, had no effect on brain TPK activity. Our data suggest that thiamine deficit can play an important role in alcohol-induced damage to brain astroglia. It is emerged that high-dose thiamine administration can represent effective treatment option against chronic effects of ethanol impact on brain structures

HIGLY STABLE NITROXIDE SPIN LABELS FOR BIOPHYSICAL RESEARCH

This work was supported by the RSF, project # 19-13-000235 and Ministry of Science and Higher Education of the Russian Federation (grant No. 14. W03.31.0034)

Морфологические особенности пневмоцистной пневмонии при ВИЧ-инфекции

Summary. In our study, pneumonia caused by Pneumocystis comprised 7.1 % of all autopsies of patients died from HIVassociated infections and was the forth cause of death following tuberculosis (35.6 %), bacterial pneumonia (16.5 %), and infectious endocarditis (10.8 %). Acute stage was more frequent (73.1 %); cavitary pneumonia was diagnosed in 7.7 % autopsies, generalized Pneumocystis infection was found in 3.8 % of cases. In 7.7 % of cases, the course of Pneumocystis pneumonia was complicated by diffuse alveolar damage. Advanced stages of Pneumocystis pneumonia should be differentiated from organizing bacterial pneumonia, pulmonary tuberculosis, and cytomegalovirus infection. In died HIVinfected patients with com bined pulmonary infection, Pneumocystis was found in 27.6 % of cases. Advanced stages of pneumonia caused by Pneumocystis and combined pul monary infection are difficult for morphological diagnosis and require a complex of modern investigations.Резюме. Пневмоцистная пневмония (ПЦП) составила 7,1 % от количества всех вскрытий умерших от ВИЧассоциированных инфекций и занимает в структуре смертности 4е место после туберкулеза (35,6 %), бактериальной пневмонии (16,5 %), инфекционного эндокардита (10,8 %). Превалировала отечная стадия ПЦП (73,1 %), в 7,7 % аутопсий констатирована кавернозная форма заболевания, в 3,8 % – генерализованный пневмоцистоз. В 7,7 % течение ПЦП осложнилось развитием диффузного альвеолярного повреждения. На поздних стадиях ПЦП необходимо морфологически дифференцировать с организацией при бактериальной пневмонии, туберкулезе, цитомегаловирусной инфекции. В 27,6 % случаев сочетанного инфекционного поражения легких у умерших от ВИЧинфекции в составе ассоциации обнаруживалась ПЦП. Случаи поздней стадии ПЦП и сочетанного поражения легких сложны для морфологической верификации, что требует использования комплекса современных исследований

НАНОРАЗМЕРНЫЙ КРЕМНИЙ, ИЗГОТОВЛЕННЫЙ С ИСПОЛЬЗОВАНИЕМ ЭЛЕКТРОЛИТА HCl : HF : C2H5OH

Results of experimental work with nanosized silicon (NcSi) samples which are not degraded under the action of intense laser radiation have been obtained. We show that that a significant increase in the intensity of thephotoluminescence signal from NC may be caused by the structural features of their formation and by the presence of a thin SiO2 layer on the surface of the nanocrystals.Представлены результаты исследований образцов наноразмерного кремния (НК), не деградирующих под действием интенсивного лазерного излучения. Показано, что значительное увеличение интенсивности сигнала фотолюминесценции от НК может быть связано как с особенностями их структурного строения, так и с наличием тонкого слоя SiO2 на поверхности нанокристаллов