314 research outputs found

    Daily dynamics of cellulase activity in arable soils depending on management practices

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    The daily dynamics of cellulase activity was studied during 27 days by the cellophane membrane method on soils managed using the conventional high-input farming system (application of mineral fertilizers and pesticides) and the biological conservation farming system (application of organic fertilizers alone) in a microfield experiment. The regular oscillatory dynamics of the cellulase activity were revealed and confirmed by the harmonic (Fourier) analysis. The oscillatory dynamics of the cellulase activity had a self-oscillatory nature and was not directly caused by the disturbing impacts of both the uncontrolled (natural) changes in the temperature and moisture (rainfall) and the controlled ones (the application of different fertilizers). The disturbing impacts affected the oscillation amplitude of the cellulase activity but not the frequency (periods) of the oscillations. The periodic oscillations of the cellulase activity were more significant in the soil under the high-input management compared to the soil under the biological farming syste

    Flow modelling and gas heating inside a profiling channel of an electric arc plasma torch

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    This paper presents a theor. model for the numerical anal. of the acceleration and heating of a gas by an elec. arc in a profiling channel with a diffuser anode. The thermal parameters and transport coeffs. of helium were detd. and the approximative expression for their calcn. in a broad range of temp. (0,3-100) kK and pressures are proposed. The calcn. and study of the effect of the thermal nonequil. plasma on the characteristics of the cylindrical arc were carried out. The results of the calcns. were compared with exptl. data and calcns. obtained from an equil. plasma model. [on SciFinder (R)

    The dual parametrization for gluon GPDs

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    We consider the application of the dual parametrization for the case of gluon GPDs in the nucleon. This provides opportunities for the more flexible modeling unpolarized gluon GPDs in a nucleon which in particular contain the invaluable information on the fraction of nucleon spin carried by gluons. We perform the generalization of Abel transform tomography approach for the case of gluons. We also discuss the skewness effect in the framework of the dual parametrization. We strongly suggest to employ the fitting strategies based on the dual parametrization to extract the information on GPDs from the experimental data.Comment: 37 pages, 2 figure

    Описание клинических случаев меланомы кожи

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    Skin melanoma is a malignant tumor originating in the cells of the melanocytic system, which is characterized by an aggressive clinical course, significant metastatic potential and unfavorable prognosis. These features of the tumor stipulate the need to improve measures to optimize early diagnosis of tumors. The article presents cases of pigmented skin melanoma to demonstrate the variability of clinical manifestations of this tumor requiring dermatologist skills in the differential diagnostics of neoplasms.Меланома кожи - злокачественное новообразование, происходящее из клеток меланоцитарной системы, характеризуется агрессивным клиническим течением, значительным метастатическим потенциалом, неблагоприятным прогнозом. Данные особенности опухоли указывают на необходимость совершенствования мер по оптимизации ранней диагностики новообразования. Описаны случаи пигментной меланомы кожи с целью демонстрации вариабельности клинических проявлений данного новообразования, требующих от врача-дерматолога навыков его дифференциальной диагностики

    Development of a Momentum Determined Electron Beam in the 1 -45 GeV Range

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    A beam line for electrons with energies in the range of 1 to 45 GeV, low contamination of hadrons and muons and high intensity up to 10^6 per accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A beam tagging system based on drift chambers with 160 micron resolution was able to measure relative electron beam momentum precisely. The resolution sigma_p p was 0.13% at 45 GeV where multiple scattering is negligible. This test beam setup provided the possibility to study properties of lead tungstate crystals (PbWO_4) for the BTeV experiment at Fermilab.Comment: 12 pages, 8 figures; work done by the BTeV Electromagnetic Calorimeter grou

    Corrosion stability of molybdenum and tungsten coatings in lead-bismuth eutectic

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    The paper presents results of corrosion tests of tungsten- and molybdenum-based protective coatings, deposited on nickel-molybdenum alloys (hastelloy) in heavy metal melts (Pb, Bi, Pb–Bi eutectic). Results of an investigation of hastelloy samples without protective coating are given for comparison. The investigations were carried out under static conditions at 550 °C. The mechanical properties of the samples under investigation have been shown that the corrosion stability of the uncoated alloys studied decreases in the order: lead – lead-bismuth eutectic – bismuth. The use of protective tungsten and molybdenum coatings ensures corrosion stability of hastalloy with retention of its mechanical properties.Наведено результати дослідження корозійної стійкості нікель-молібденових сплавів (хастелой) в розплавах важких металів (Pb, Bi, Pb-Bi). Корозію вивчено в статичних умовах при температурі 550 °С. Встановлено, що в ряді розплавів свинець – свинець-вісмутова евтектика – вісмут корозійна стійкість вивчених сплавів падає. Показано, що використання захисних покрить з вольфраму та молібдену підвищує корозійну стійкість хастелою.Представлены результаты исследования коррозионной стойкости никель-молибденовых сплавов (хастеллой) в расплавах тяжелых металлов (Pb, Bi, Pb-Bi). Коррозия изучена в статических условиях при температуре 550 °С. Установлено, что в ряду расплавов свинец – свинец-висмутовая эвтектика – висмут коррозионная стойкость изученных сплавов падает. Показано, что использование защитных покрытий из вольфрама и молибдена повышает коррозионную стойкость хастеллоя
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