374 research outputs found

    Alpha decay chains study for the recently observed superheavy element Z=117 within the Isospin Cluster Model

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    The recently observed α\alpha-decay chains 293294117^{293-294}117 were produced by the fusion reactions with target 249Bk^{249}Bk and projectile 48Ca^{48}Ca at Dubna in Russia. The reported cross-sections for the mentioned reaction are σ=0.5(+1.1,0.4)\sigma=0.5(+1.1,-0.4)pb and σ\sigma=1.3(+1.5,-0.6)pbpb at E=35MeVE^{*}=35MeV and E=39MeVE^{*}=39MeV, respectively. The Q-values of α\alpha-decay and the half-lives Log10T1/2αLog_{10}T^{\alpha}_{1/2}(s) are calculated for the α\alpha-decay chains of 293294117^{293-294}117 nuclei, within the framework of Isospin Cluster Model (ICM). In the ICM model the proximity energy is improved by using the isospin dependent radius of parent, daughter and alpha particle. The binding energy B(Ai,Zi)B(A_{i}, Z_{i}) (i=1,2) of any nucleus of mass number A and atomic number Z was obtained from a phenomenological and more genaralized BW formula given by \cite{samanta02}. The calculated results in ICM are compared with the experimental results and other theoretical Macro-Microscopic(M-M), RMF(with NL3 and SFU Gold forces parameter) model calculations. The estimated values of α\alpha-decay half-lives are in good agreement with the recent data. The ICM calculation is in favor of the persence of magic number at N=172

    Kinetics of dislocation ensembles in deformable irradiated materials

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    The development of plastic instability in the initial deformation stages of irradiated materials is studied. The dependence of the fraction of dislocations which overcome obstacles in the dynamic regime (dislocation ‘‘channeling’’) on the degree of radiation hardening (irradiation dose) and the dislocation velocity is analyzed. It is shown that this effect plays a role in radiation embrittlement of reactor materialsyesBelgorod State Universit

    Role of internal stresses in the localization of plastic flow of irradiated materials

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    The collective behavior of dislocations in irradiated materials is studied using the kinetic equation for the dislocation density, taking account of a Burgers-type nonlinearity. It is shown that the degree of dislocation localization in slip bands is higher in the irradiated materials than in the unirradiated materialsyesBelgorod State Universit

    Search for long lived heaviest nuclei beyond the valley of stability

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    The existence of long lived superheavy nuclei (SHN) is controlled mainly by spontaneous fission and α\alpha-decay processes. According to microscopic nuclear theory, spherical shell effects at Z=114, 120, 126 and N=184 provide the extra stability to such SHN to have long enough lifetime to be observed. To investigate whether the so-called "stability island" could really exist around the above Z, N values, the α\alpha-decay half lives along with the spontaneous fission and β\beta-decay half lives of such nuclei are studied. The α\alpha-decay half lives of SHN with Z=102-120 are calculated in a quantum tunneling model with DDM3Y effective nuclear interaction using QαQ_\alpha values from three different mass formulae prescribed by Koura, Uno, Tachibana, Yamada (KUTY), Myers, Swiatecki (MS) and Muntian, Hofmann, Patyk, Sobiczewski (MMM). Calculation of spontaneous fission (SF) half lives for the same SHN are carried out using a phenomenological formula and compared with SF half lives predicted by Smolanczuk {\it et al}. Possible source of discrepancy between the calculated α\alpha-decay half lives of some nuclei and the experimental data of GSI, JINR-FLNR, RIKEN are discussed. In the region of Z=106-108 with N\sim 160-164, the β\beta-stable SHN 106268Sg162^{268}_{106}Sg_{162} is predicted to have highest α\alpha-decay half life (Tα3.2hrsT_\alpha \sim 3.2hrs) using QαQ_\alpha value from MMM. Interestingly, it is much greater than the recently measured TαT_\alpha (22s\sim 22s) of deformed doubly magic 108270Hs162^{270}_{108}Hs_{162} nucleus. A few fission-survived long-lived SHN which are either β\beta-stable or having large β\beta-decay half lives are predicted to exist near 294110184^{294}110_{184}, 293110183^{293}110_{183}, 296112184^{296}112_{184} and 298114184^{298}114_{184}. These nuclei might decay predominantly through α\alpha-particle emission.Comment: 14 pages, 6 figures, 1 tabl

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

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    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

    Методические аспекты повышения качества услуг в сфере транспортной логистики

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    Розробка методичних аспектів підвищення якості обслуговування в транспортно-логістичних компаніях на основі вимог міжнародних стандартів якості ISO 9000:2008 з використанням простих інструментів контролю якості.Article on developing methodological aspects of service quality improvement in transportation and logistics companies, based on the requirements of international quality standards ISO 9000:2008, using simple tools of quality control. This paper defines the key issues to improve the quality of logistics services, approaches to the selection of methods and tools to ensure continuous improvement of transport and logistics companies. The mechanisms of implementing the requirements of the standard relating to the measurement of the quality of the provision of logistics services. The essence of the method and the role of «six sigma» in implementing the concept of «zero defects». Defines the approaches to the selection criteria and evaluation methodology for outsourcing companies, and recommendations on the use of quality control tools to improve the quality of logistics services.Разработка методических аспектов повышения качества обслуживания в транспортно-логистических компаниях на основе требований международных стандартов качества ISO 9000:2008 с использованием простых инструментов контроля качества

    On athermic mechanism of materials radiation embrittlement

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    To elucidate the mehanisms of radiation embrittlement of materials the temperature dependence of mechanical properties of irradiated materials has been studiedyesBelgorod State Universit

    Лечение больных инфарктом миокарда в современных условиях регионального сосудистого центра

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    The article highlights the problem of providing care for patients with acute coronary syndrome, given the high myocardial infarction (mi) morbidity and mortality among the youth population. The main method of managing acute myocardial infarction is reperfusion therapy, performing revascularization with percutaneous coronary intervention (pci) in the shortest possible time from the disease onset. Only rational and timely treatment can reduce mortality after mi, the frequency of its complications, as well the period of inpatient treatment and disability of the population.В статье освещается проблема оказания помощи больным с острым коронарным синдромом, учитывая высокую заболеваемость и летальность молодого населения от инфаркта миокарда (ИМ). Основным методом лечения острого ИМ является реперфузионная терапия — выполнение реваскуляризации с чрескожным коронарным вмешательством в кратчайшие сроки заболевания. Только рациональное и своевременное лечение позволяет снизить летальность при ИМ и частоту его осложнений, а также уменьшить период стационарного лечения и инвалидизацию населения

    B-blockers, calcium antagonists, and mortality in stable coronary artery disease: An international cohort study

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    Aims: The effect of first-line antianginal agents, β-blockers, and calcium antagonists on clinical outcomes in stable coronary artery disease (CAD) remains uncertain. Methods and results We analysed the use of β-blockers or calcium antagonists (baseline and annually) and outcomes in 22 006 stable CAD patients (enrolled 2009–2010) followed annually to 5 years, in the CLARIFY registry (45 countries). Primary outcome was all-cause death. Secondary outcomes were cardiovascular death and the composite of cardiovascular death/non-fatal myocardial infarction (MI). After multivariable adjustment, baseline β-blocker use was not associated with lower all-cause death [1345 (7.8%) in users vs. 407 (8.4%) in non-users; hazard ratio (HR) 0.94, 95% confidence interval (CI) 0.84–1.06; P = 0.30]; cardiovascular death [861 (5.0%) vs. 262 (5.4%); HR 0.91, 95% CI 0.79–1.05; P = 0.20]; or cardiovascular death/non-fatal MI [1272 (7.4%) vs. 340 (7.0%); HR 1.03, 95% CI 0.91–1.16; P = 0.66]. Sensitivity analyses according to β-blocker use over time and to prescribed dose produced similar results. Among prior MI patients, for those enrolled in the year following MI, baseline β-blocker use was associated with lower all-cause death [205 (7.0%) vs. 59 (10.3%); HR 0.68, 95% CI 0.50–0.91; P = 0.01]; cardiovascular death [132 (4.5%) vs. 49 (8.5%); HR 0.52, 95% CI 0.37–0.73; P = 0.0001]; and cardiovascular death/non-fatal MI [212 (7.2%) vs. 59 (10.3%); HR 0.69, 95% CI 0.52–0.93; P = 0.01]. Calcium antagonists were not associated with any difference in mortality. Conclusion In this contemporary cohort of stable CAD, β-blocker use was associated with lower 5-year mortality only in patients enrolled in the year following MI. Use of calcium antagonists was not associated with superior mortality, regardless of history of MI

    Photometric observations of the supernova 2009nr

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    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
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