Electro-Conductive Composites Based on Metal Oxides and Carbon Nanostructures

Optimal conditions were found for the formation of carbon-oxide composites by the treatment of mixtures of oxides of aluminum or titanium with carbon nanotubes and nanofibers in a planetary ball mill. The dependences of the electrical conductivity of composites on the content of carbon nanomaterials (1-5% by mass) were determined. It is shown that the addition of 3%(wt) of CNT to the oxides leads to a sharp increase in the electrical conductivity: from 5.0×10-8 to 2.8×10-4 S/cm for Al2O3 and from 5.0×10-6 to 2.2×10-2 S/cm for TiO2. It was shown that the carbon-oxide composites are promising carriers of the catalysts of electrode processes in electrochemical devices. It was revealed that Pt/TiO2 - CNT catalyst containing 5% (mass) of carbon nanotubes has the best catalytic activity in oxygen reduction, in an electrode-modeling cathode of a fuel cell. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3512

Detectors of charged particles and low-energy gamma-quanta on the basis of Ticor single crystals

Scintillation characteristics have been studied for detectors of charged particles and low-energy gamma-quanta produced on the basis of Ticor single crystals.У роботі представлені результати досліджень сцинтиляційних характеристик детекторів заряджених часток і низькоенергетичних гамма-квантів на основі кристалів тікору.В работе представлены результаты исследований сцинтилляционных характеристик детекторов заряженных частиц и низкоэнергетических гамма-квантов на основе кристаллов тикора

Hydrological (in)stability in Southern Siberia during the Younger Dryas and early Holocene

Southern Siberia is currently undergoing rapid warming, inducing changes in vegetation, loss of permafrost, and impacts on the hydrodynamics of lakes and rivers. Lake sediments are key archives of environmental change and contain a record of ecosystem variability, as well as providing proxy indicators of wider environmental and climatic change. Investigating how hydrological systems have responded to past shifts in climate can provide essential context for better understanding future ecosystem changes in Siberia. Oxygen isotope ratios within lacustrine records provide fundamental information on past variability in hydrological systems. Here we present a new oxygen isotope record from diatom silica (ẟ18Odiatom) at Lake Baunt (55°11′15″N, 113°01,45″E), in the southern part of eastern Siberia, and consider how the site has responded to climate changes between the Younger Dryas and Early to Mid Holocene (ca. 12.4 to 6.2 ka cal BP). Excursions in ẟ18Odiatom are influenced by air temperature and the seasonality, quantity, and source of atmospheric precipitation. These variables are a function of the strength of the Siberian High, which controls temperature, the proportion and quantity of winter versus summer precipitation, and the relative dominance of Atlantic versus Pacific air masses. A regional comparison with other Siberian ẟ18Odiatom records, from lakes Baikal and Kotokel, suggests that ẟ18Odiatom variations in southern Siberia reflect increased continentality during the Younger Dryas, delayed Early Holocene warming in the region, and substantial climate instability between ~10.5 to ~8.2 ka cal BP. Unstable conditions during the Early Holocene thermal optimum most likely reflect localised changes from glacial melting. Taking the profiles from three very different lakes together, highlight the influence of site specific factors on the individual records, and how one site is not indicative of the region as a whole. Overall, the study documents how sensitive this important region is to both internal and external forcing

Confining QCD Strings, Casimir Scaling, and a Euclidean Approach to High-Energy Scattering

We compute the chromo-field distributions of static color-dipoles in the fundamental and adjoint representation of SU(Nc) in the loop-loop correlation model and find Casimir scaling in agreement with recent lattice results. Our model combines perturbative gluon exchange with the non-perturbative stochastic vacuum model which leads to confinement of the color-charges in the dipole via a string of color-fields. We compute the energy stored in the confining string and use low-energy theorems to show consistency with the static quark-antiquark potential. We generalize Meggiolaro's analytic continuation from parton-parton to gauge-invariant dipole-dipole scattering and obtain a Euclidean approach to high-energy scattering that allows us in principle to calculate S-matrix elements directly in lattice simulations of QCD. We apply this approach and compute the S-matrix element for high-energy dipole-dipole scattering with the presented Euclidean loop-loop correlation model. The result confirms the analytic continuation of the gluon field strength correlator used in all earlier applications of the stochastic vacuum model to high-energy scattering.Comment: 65 pages, 13 figures, extended and revised version to be published in Phys. Rev. D (results unchanged, 2 new figures, 1 new table, additional discussions in Sec.2.3 and Sec.5, new appendix on the non-Abelian Stokes theorem, old Appendix A -> Sec.3, several references added

Oxygen isotope composition of diatoms from sediments of Lake Kotokel (Buryatia).

This is a summary of new oxygen isotope data for diatoms from Lake Kotokel sediments, with implications for responses of the lake system and its environment to global change over the past 46 kyr. Fossil diatoms in all samples are free from visible contamination signatures and contain no more than 2.5% Al2O3, which ensures reliable reconstructions. The δ18O values in diatoms vary between +23.7 and +31.2‰ over the record. The results mainly represent diatom assemblages of summer blooming periods, except for the time span between 36 and 32 kyr, when the isotopic signal rather records a shift from summer to spring blooming conditions. Possible water temperature changes only partly explain the changes in the isotopic record. The observed isotopic patterns are produced mainly by isotope changes in lake water in response to variations in air temperature, hydrology, and atmospheric circulation in the region. During Marine Isotope Stage (MIS) 2 (Last Glacial maximum), high δ18Odiatom resulted from rapid evaporation and low fluvial inputs. The high δ18O values of about +29 to +30‰ during the first half of MIS 1 (Holocene interglacial) suggest an increased share of summer rainfalls associated with southern/southeastern air transport. The δ18O decrease to +24‰ during the second half of MIS 1 is due to the overall hemispheric cooling and increased moisture supply to the area by the Atlantic transport. The record of Lake Kotokel sediments provides an example of complex interplay among several climatic controls of δ18Odiatom in the Late Pleistocene and the Holocene

Researching the efficiency of block statistical data compression method

У статті розглянутий блочно-статистичний алгоритм стиснення інформації, котрий є модифікацією класичного алгоритму Хаффмана, який до цього часу є затребуваним у сучасних алгоритмах стиснення та обробки інформації. Було проведено дослідження ефективності розробленого алгоритму для різних типів вхідних даних у порівнянні з оригінальним. Зроблені висновки щодо доцільності використання алгоритму для стиснення у реальних базах даних, та необхідності його подальшого дослідження.В статье рассмотрен блочно-статистический алгоритм сжатия, который является модификацией классического алгоритма Хаффмана, который и до сего времени является востребованным в современных алгоритмах сжатия и обработки информации. Было проведено исследование эффективности разработанного алгоритма для различных типов входных данных по сравнению с оригинальным. Сделаны выводы о целесообразности использования алгоритма для сжатия в реальных базах данных и необходимости его дальнейшего исследования.This article discusses statistical block compression algorithm, which is a modification of the classical Huffman algorithm, and it's still being used in modern compression algorithms and information processing. Research was conducted to find out the efficiency of the modified algorithm for different types of input data. Conclusions were made about using algorithm in real databases for data compression and the need for further study

Review and comparative analysis of data compression methods

У статті розглянуті найбільш поширені алгоритми стиснення інформації, що використовуються для обробки текстових, графічних та відеоданих. Проведено їх порівняльний аналіз та виділені сильні та слабкі сторони. Стисло розповідається про ключові моменти функціонування кожного алгоритму, наведені приклади програмного забезпечення та технології, що базуються на них. Робиться висновок про доцільність використання модифікованого методу Хаффмана при стисненні текстових значень у базах даних.В статье рассмотрены наиболее распространенные алгоритмы сжатия информации, которые используются для обработки текстовых, графических и видеоданных. Проведен сравнительный анализ и выделены их сильные и слабые стороны. Кратко рассказывается о ключевых моментах функционирования каждого алгоритма, приведенные примеры программного обеспечения и технологий, которые базируются на них. Делается вывод о целесообразности использования модифицированного метода Хаффмана при сжатии текстовых значений в базах данных.This article discusses the most common data compression algorithms , compares them and stresses the main advantages and weaknesses. Briefly describes the main principles of each algorithm. Examples of software and technologies which are based on them are given. The conclusion about the expedience of using the modified method of Huffman for compression of text values in the database are drawn

Luminescence energy yields of organic solid materials exited by photons of light or gamma-radiation

In this paper we compare the energy yields both for the case of excitation by light photons of the visible range and for the excitation by gamma radiation for some organic scintillation crystals and polystyrene plastic scintillator. In the first case the energy of excitation is lower than the ionization potential of molecules, and in the second one the energy of excitation is higher than the ionization potential of molecules. It has been obtained that the energy yield in the case of excitation by photons of gamma radiation Yy is in the range from 0.018 to 0.056. These values are an order of magnitude smaller than the energy yield Yf obtained for photoexcitation