Non-rigid Shell Model and Correlational Mechanism of the Local Pairing

The Hartree-Fock states of the many-electron atomic system can be unstable with respect to a static or dynamic shift of the electron shells. An appropriate non-rigid shell model for atomic clusters is developed. It permits to formulate a convenient approach to the semiempirical description of the different correlation effects and to reveal some new effects.Comment: 3 pages, 2 ".gif" figures, LaTeX; will be published in Physica C in Materials of Int.Conf. HTSC-V. (1997, Beijing, China

Properties of tubes from Zr-1% Nb alloy after thermochemical treatment and hydrogenation

The influence of treatment in controlled gas environments with subsequent hydrogenation on the physical and mechanical characteristics of the Zr-1% Nb zirconium alloy has been investigated. The surface hardness and the size of the diffusion-hardened layer of the ring-samples cut from fuel tubes from the Zr-1% Nb alloy after treatment in oxygen- and nitrogen-containing gaseous media with subsequent saturation with hydrogen have been established. The influence of the parameters of the gaseous medium and the modes of thermochemical treatment (TCT) of specimens-rings on the destructive stresses under static load at temperatures of 20 and 380 °C is shown. It was revealed that treatment in the investigated gas environment increases the resistance to hydrogen saturation and has a positive effect on the long-term strength of ring specimens from the zirconium alloy Zr-1% Nb.Досліджено вплив термохімічної обробки в контрольованих газових середовищах з наступним насиченням воднем на фізико-механічні характеристики цирконієвого сплаву Zr-1% Nb. Визначено твердість поверхні і розмір дифузійно-зміцненого шару зразків-кілець, вирізаних з твельних трубок сплаву Zr-1% Nb після обробки в кисне- і азотовмісних газових середовищах, а також з наступним насиченням воднем. Показано вплив параметрів газового середовища і режимів термохімічної обробки зразків-кілець на руйнівні напруження за статичного тривалого навантаження за температурах 20 і 380 °С. Виявлено, що обробка в дослідженому газовому середовищі підвищує опірність насиченню воднем і позитивно впливає на тривалу міцність зразків-кілець з цирконієвого сплаву Zr-1% Nb.Исследовано влияние термохимической обработки в контролируемых газовых средах с последующим наводороживанием на физико-механические характеристики циркониевого сплава Zr-1% Nb. Установлены твердость поверхности и размер диффузионно-упрочненного слоя образцов-колец, вырезанных из твэльных трубок из сплава Zr-1% Nb после обработки в кислород- и азотсодержащих газовых средах с последующим насыщением водородом. Показаны влияния параметров газовой среды и режимов термохимической обработки образцов-колец на напряжения разрушения при статической нагрузке при температурах 20 и 380 °С. Выявлено, что обработка в исследованных газовых средах повышает сопротивляемость насыщению водородом и положительно влияет на длительную прочность образцов-колец из циркониевого сплава Zr-1% Nb

Effect of ausforming on mechanical properties of 12%Cr ferritic/martensitic steel

Effects of ausforming through upsetting at 890 °C and following tempering on microstructure and mechanical properties under uniaxial tension of 12CrWMoNbVB ferritic/martensitic steel are studied. Electron microscopic investigations along with elemental analysis of the steel samples in various states provided detailed information about subgrain structure and typical precipitates, the latter mainly М₂₃С₆ and NbC carbides. Strength and plasticity parameters (σ₀, σb, δ) are examined and shown to enhance under applied thermomechanical treatment as compared to standard characteristics of the steel. Preferred treatment of the steel is preliminarily evaluated.Досліджено вплив аусформінгу шляхом осаджування при 890 °C та подальшого відпускання на мікроструктуру і механічні властивості за одновісного розтягу феритомартенситної сталі 12CrWMoNbVB (18Х12ВМБФР – за ГОСТ 5632-72). Електронно-мікроскопічні дослідження, а також елементний аналіз зразків сталі в різних станах дозволили отримати детальну інформацію про субзеренну структуру та типові виділення. Останні переважно представлені карбідами М₂₃С₆ та NbC. Досліджено параметри міцності та пластичності (σ₀, σb, δ), котрі покращуються після застосованої обробки у порівнянні зі стандартними характеристиками сталі. Попередньо оцінено переважну обробку сталі.Исследовано влияние аусформинга путем осадки при 890 °C и последующего отпуска на микроструктуру и механические свойства при одноосном растяжении ферритомартенситной стали 12CrWMoNbVB (18Х12ВМБФР – по ГОСТ 5632-72). Электронно-микроскопические исследования, а также элементный анализ образцов стали в различных состояниях позволили получить подробную информацию о субзеренной структуре и типичных выделениях. Последние в основном представлены карбидами М₂₃С₆ и NbC. Исследованы параметры прочности и пластичности (σ₀, σb, δ), которые улучшаются при применяемой термомеханической обработке по сравнению со стандартными характеристиками стали. Предварительно оценивается предпочтительная обработка стали

Status of the GAMMA-400 Project

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV - 3 TeV is presented. The angular resolution of the instrument, 1-2{\deg} at E{\gamma} ~100 MeV and ~0.01^{\circ} at E{\gamma} > 100 GeV, its energy resolution ~1% at E{\gamma} > 100 GeV, and the proton rejection factor ~10E6 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.Comment: 6 pages, 1 figure, 1 table, submitted to Advances in Space Researc

The Scientific Foundations of Forecasting Magnetospheric Space Weather

The magnetosphere is the lens through which solar space weather phenomena are focused and directed towards the Earth. In particular, the non-linear interaction of the solar wind with the Earth's magnetic field leads to the formation of highly inhomogenous electrical currents in the ionosphere which can ultimately result in damage to and problems with the operation of power distribution networks. Since electric power is the fundamental cornerstone of modern life, the interruption of power is the primary pathway by which space weather has impact on human activity and technology. Consequently, in the context of space weather, it is the ability to predict geomagnetic activity that is of key importance. This is usually stated in terms of geomagnetic storms, but we argue that in fact it is the substorm phenomenon which contains the crucial physics, and therefore prediction of substorm occurrence, severity and duration, either within the context of a longer-lasting geomagnetic storm, but potentially also as an isolated event, is of critical importance. Here we review the physics of the magnetosphere in the frame of space weather forecasting, focusing on recent results, current understanding, and an assessment of probable future developments.Peer reviewe

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Evaluation of latent period of temperature sensitivity in traditional and unilateral spinal anesthesia

Objective: evaluation of the differences in the level of temperature, sensory and motor blockade during the various techniques of spinal anesthesia. Materials and Methods. Prospectively the randomized study included 70 patients. In the group with conventional spinal anesthesia (n=35) 15mg of bupivacaine injected quickly. In the group with unilateral spinal anesthesia (n=35) 7.5mg of bupivacaine administered slowly, at a rate of 1 ml per minute. We studied the level of temperature and time, sensory and motor blockade. The data are statistically processed. Results. Reduced thermal sensitivity recorded in an average of 48 seconds as a unilateral spinal anesthesia group and the control group. Subarachnoid administration of 7.5 mg of hyperbaric bupivacaine resulted in the development of a complete motor blockade underlying lower extremity in only 16 patients (45.7%). Conclusion. Using lower dosages of bupivacaine for unilateral spinal anesthesia lowers the threshold concentration of the local anesthetic in the subarachnoid space, resulting in slower motor neuron blockade and it is not total in more than 50% of cases