374 research outputs found
Alpha decay chains study for the recently observed superheavy element Z=117 within the Isospin Cluster Model
The recently observed -decay chains were produced by
the fusion reactions with target and projectile at Dubna
in Russia. The reported cross-sections for the mentioned reaction are
pb and =1.3(+1.5,-0.6) at and
, respectively. The Q-values of -decay and the half-lives
(s) are calculated for the -decay chains of
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 (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
-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
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
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
The existence of long lived superheavy nuclei (SHN) is controlled mainly by
spontaneous fission and -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 -decay half lives along with the spontaneous
fission and -decay half lives of such nuclei are studied. The
-decay half lives of SHN with Z=102-120 are calculated in a quantum
tunneling model with DDM3Y effective nuclear interaction using
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 -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
160-164, the -stable SHN is predicted to have
highest -decay half life () using
value from MMM. Interestingly, it is much greater than the recently measured
() of deformed doubly magic
nucleus. A few fission-survived long-lived SHN which are either -stable
or having large -decay half lives are predicted to exist near
, , and .
These nuclei might decay predominantly through -particle emission.Comment: 14 pages, 6 figures, 1 tabl
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
Методические аспекты повышения качества услуг в сфере транспортной логистики
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
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
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
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
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
- …