Radiogenic Lead with Dominant Content of 208 Pb: New Coolant and Neutron Moderator for Innovative Nuclear Facilities

As a rule materials of small atomic weight (light and heavy water, graphite, and so on) are used as neutron moderators and reflectors. A new very heavy atomic weight moderator is proposed-radiogenic lead consisting mainly of isotope 208 Pb. It is characterized by extremely low neutron radiative capture cross-section (0.23 mbarn for thermal neutrons, i.e., less than that for graphite and deuterium) and highest albedo of thermal neutrons. It is evaluated that the use of radiogenic lead makes it possible to slow down the chain fission reaction on prompt neutrons in a fast reactor. This can increase safety of the fast reactors and reduce as well requirements pertaining to the fuel fabrication technology. Radiogenic lead with high 208 Pb content as a liquid-metal coolant of fast reactors helps to achieve a favorable (negative) reactivity coefficient on coolant temperature. It is noteworthy that radiogenic lead with high 208 Pb content may be extracted from thorium (as well as thorium-uranium) ores without isotope separation. This has been confirmed experimentally by the investigations performed at San Paulo University, Brazil

MYCOBACTERIOSIS IN THE PRACTICE OF PULMONOLOGISTS AND PHTHISIOLOGISTS

Goal of the study: to investigate the frequency of mycobacteriosis in the practice of pulmonologists and phthisiologists.Materials and methods. The analysis included medical files of 156 patients with various non-specific respiratory diseases and tuberculosis who were examined in 2011-2014 and non-tuberculous mycobacteria were found in their sputum.Results of the study. pulmonary mycobacteriosis was diagnosed in 93 (59.6%) patients out of 156 who corresponded the criteria of American Thoracic Society and etiotropic treatment was prescribed. While detection of non-tuberculous mycobacteria in the other patients was considered as innidiation of respiratory tract by those mycobacteria in case of chronic non-specific pulmonary disease and/or tuberculosis. Mycobacterioses were treated with the relevance to drug susceptibility of the causative agent and there were numerous obstacles due to high frequency of adverse reactions

MEASURES DIRECTED TO PREVENTION OF IMPORTATION AND DISSEMINATION OF SEVERE ACUTE RESPIRATORY SYNDROME (SARS) AT AMURSKAYA PROVINCE TERRITORY

A complex of organizingmethodical, medical preventive and antiepidemic measures both at the frontier passing points and on the whole Amurskaya Province prior to detection of a SARS case in Blagoveshchensk City and from the moment of the disease registration to prevent further dissemination of this infection is represented

Сравнительный анализ характеристик бандажей колёсных пар, закалённых с использованием лазерного и плазменного источника тепла

Lateral wear of the locomotive wheel flange is one of the main types of wear that occurs during rolling stock operation. An important characteristic of a rail wheel rim is its wear resistance, which directly depends on the carbon content in steel. The carbon content in wheel steel of group 2 in the amount of 0,55–0,65 is due to the fact that at its lower concentration, the proportion of grain boundary ferrite increases, which leads to a decrease in the contact strength of wheels, and a higher one leads to a tendency to brittle fracture.The increased carbon content makes it possible to harden the surface of steel. Plasma and laser hardening technologies can be used to reduce tyre flange wear and increase the service life of locomotive wheelsets.The objective of this work is to determine advantages and disadvantages of technologies for laser and plasma hardening of working surfaces of tyres of wheelsets of railway rolling stock.The comparative analysis related to microstructure and microhardness of wheelsets tyres of the 2TE25KM diesel locomotive which are made of wheel steel of group 2 according to GOST 398-2010 state standard and hardened respectively by plasma and laser hardening.The tasks set were solved using theoretical and experimental research methods. The preparation and study of hardened samples was carried out using the equipment of the testing laboratory of LLC Scientific and Technical Association «IRE-Polus».A study referred to hardened zones in various areas and sections of the tyre. Tribological tests concerned wear resistance of specimens hardened with a high-power fiber laser. The main advantages and disadvantages of laser and plasma hardening processes are revealed.The conducted studies allow making a conclusion that the use of laser hardening technology for hardening wheelsets tyres, as an alternative to the plasma hardening process, is highly promising.Боковой износ гребня колёсной пары локомотива является одним из основных видов износа, возникающего при эксплуатации подвижного состава. Важной характеристикой обода железнодорожного колеса является его износостойкость, которая напрямую зависит от содержания углерода в стали. Содержание углерода в колёсной стали 2 в количестве 0,55–0,65 связано с тем, что при его меньшей концентрации увеличивается доля зернограничного феррита, что приводит к снижению контактной прочности колёс, а при большей – приводит к склонности к хрупкому разрушению.Повышенное содержание углерода позволяет осуществить закалку поверхности стали. Для уменьшения износа гребня бандажа и увеличения ресурса колёсных пар локомотивов возможно применение технологий плазменного и лазерного упрочнения.Целью данной работы является определение преимуществ и недостатков технологий лазерного и плазменного упрочнения рабочих поверхностей бандажей колёсных пар железнодорожного подвижного состава.В работе проводится сравнительный анализ микроструктуры и микротвёрдости упрочнённых методом плазменной и лазерной закалки бандажей колёсных пар тепловоза 2ТЭ25КМ, выполненных из колёсной стали 2 ГОСТ 398-2010.Поставленные задачи решались с использованием теоретических и экспериментальных методов исследования.Подготовка и исследование закалённых образцов выполнено на оборудовании испытательной лаборатории ООО НТО «ИРЭ-Полюс».Проведено исследование зон упрочнения в различных областях и участках бандажа. Проведены трибологические испытания на износостойкость образцов, закалённых с использованием высокомощного волоконного лазера. Выявлены основные преимущества и недостатки процессов лазерной и плазменной закалки.Проведённые исследования позволяют сделать вывод о высокой перспективности применения технологии лазерной закалки для упрочнения бандажей колёсных пар как альтернативы процессу плазменного упрочнения

Assessment of the possibility for large-scale 238Pu production in a VVER-1000 power reactor

The paper presents the estimates for the possibility for large-scale production of 238Pu in the core of a VVER-1000 power reactor. The Np-fraction of minor actinides extracted from transuranic radioactive waste is proposed to be used as the starting material. The irradiation device with NpO2 fuel elements is installed at the reactor core center. The NpO2 fuel lattice pitch is varied and the irradiation device is surrounded by a heavy moderator layer to create the best possible spectral conditions for large-scale production (~ 3 kg/year) of conditioned plutonium with the required isotopic composition (not less than 85% of 238Pu and not more than 2 ppm of 236Pu). Plutonium with such isotopic composition can be used as the thermal source in thermoelectric radioisotope generators and in cardiac pacemakers. It has been demonstrated that the estimated scale of the 238Pu production in a VVER-type power reactor exceeds considerably the existing scale of its production in research reactors

Cycloaddition of alkynes to diimino Mo3S4 cubane-type clusters: a combined experimental and theoretical approach

A heterocyclic ligand 4,40-di-tert-butyl-2,20-bipyridine (dbbpy) has been coordinated to the Mo3S4 cluster unit affording the complex [Mo3S4Cl3(dbbpy)3]+ ([1]+) in a one-step ligand-exchange protocol from [Mo3S4(tu)8(H2O)]Cl4 4H2O (tu = thiourea). The new cluster was isolated as [1]PF6 and [1]Cl salts in high yields and the crystal structure of the latter determined by X-ray analysis. The synthetic procedure was extended to tungsten to afford [W3S4Cl3(dbbpy)3]+ ([2]+). Kinetic and NMR studies show that [1]+ reacts with several alkynes to form dithiolene species via concerted [3+2] cycloaddition reactions whereas [2]+ remains inert under similar conditions. The different rates for the reactions of [1]+ are rationalised by computational (DFT) calculations, which show that the more electron-withdrawing the substituents of the alkyne the faster the reaction. The inertness of [2]+ is due to the endergonicity of its reactions, which feature DGr values systematically 5–7 kcal mol 1 more positive than for those of [1]+

A transverse current rectification in graphene superlattice

A model for energy spectrum of superlattice on the base of graphene placed on the striped dielectric substrate is proposed. A direct current component which appears in that structure perpendicularly to pulling electric field under the influence of elliptically polarized electromagnetic wave was derived. A transverse current density dependence on pulling field magnitude and on magnitude of component of elliptically polarized wave directed along the axis of a superlattice is analyzed.Comment: 12 pages, 6 figure

Acoustic and oceanographic observations and configuration information for the WHOI moorings from the SW06 experiment

This document describes data, sensors, and other useful information pertaining to the moorings that were deployed from the R/V Knorr from July 24th to August 4th, 2006 in support of the SW06 experiment. The SW06 experiment was a large, multi-disciplinary effort performed 100 miles east of the New Jersey coast. A total of 62 acoustic and oceanographic moorings were deployed and recovered. The moorings were deployed in a “T” geometry to create an along-shelf path along the 80 meter isobath and an across-shelf path starting at 600 meters depth and going shoreward to a depth of 60 meters. A cluster of moorings was placed at the intersection of the two paths to create a dense sensor-populated area to measure a 3-dimensional physical oceanography. Environmental moorings were deployed along both along-shelf and across-shelf paths to measure the physical oceanography along those paths. Moorings with acoustic sources were placed at the outer ends of the “T” to propagate various signals along these paths. Five single hydrophone receivers were positioned on the across shelf path and a vertical and horizontal hydrophone array was positioned at the intersection of the “T” to get receptions from all the acoustics assets that were used during SW06.Funding was provided by the Office of Naval Research under Contract No. N00014-04-1014