The Multisensor Array Based on Grown-On-Chip Zinc Oxide Nanorod Network for Selective Discrimination of Alcohol Vapors at Sub-ppm Range

We discuss the fabrication of gas-analytical multisensor arrays based on ZnO nanorods grown via a hydrothermal route directly on a multielectrode chip. The protocol to deposit the nanorods over the chip includes the primary formation of ZnO nano-clusters over the surface and secondly the oxide hydrothermal growth in a solution that facilitates the appearance of ZnO nanorods in the high aspect ratio which comprise a network. We have tested the proof-of-concept prototype of the ZnO nanorod network-based chip heated up to 400 °C versus three alcohol vapors, ethanol, isopropanol and butanol, at approx. 0.2–5 ppm concentrations when mixed with dry air. The results indicate that the developed chip is highly sensitive to these analytes with a detection limit down to the sub-ppm range. Due to the pristine differences in ZnO nanorod network density the chip yields a vector signal which enables the discrimination of various alcohols at a reasonable degree via processing by linear discriminant analysis even at a sub-ppm concentration range suitable for practical applications

Fractal analysis of the AFM-images of Cu–Ga–Se films, prepared by chemical bath deposition

С использованием атомно-силовой микроскопии исследована морфология поверхности тонких пленок Cu–Ga–Se, полученных совместным гидрохимическим осаждением селенидов меди (I) Cu2Se и галлия Ga2Se3. С помощью фрактального анализа АСМ-изображений установлена зависимость между условиями осаждения тонких пленок Cu–Ga–Se и их фрактальной размерностью, рассчитанной методом подсчета кубов и методом триангуляции. Также предложен механизм формирования и роста пленок при гидрохимическом осаждении диселенида меди (I) и галлия.The surface morphology of Cu–Ga–Se thin films prepared by chemical bath deposition of copper (I) Cu2Se and gallium selenides Ga2Se3 was investigated by means of an atomic-force microscopy. The dependence between the conditions of the deposition of Cu–Ga–Se thin films and their fractal dimension, calculated by counting cubes and by triangulation, was defined by means of fractal analysis. A mechanism for the formation and growth of films at chemical bath deposition of copper (I) and gallium selenides was proposed well as.Программа развития УрФУ на 2013 год (п.1.2.2.3

Моделирование трехмерных пористых иерархических материалов, организованных посредством самосборки наносфер

The article considers possibilities of using modeling fo r the development of two promising areas of modern nanomaterials, i. e.  materials with a hierarchy of pores organized hierarchical self- assembly and hierarchical structures with nanoporous elements. The  pore size of hierarchical structures was estimated by means of quasi- two-dimensional projection of three-dimensional deterministic fractal Julien aggregate. Three-dimensional modeling of hierarchical  structures organized by means of nanosphere self-assembly was conducted in the Autodesk 3ds Max environment. The article provides analysis of dependences of porosity, density, specific  surface area of fractal structures on the size of aggregates (with the  appearance of new pore levels of hierarchical materials),  dependences of the porosity change in the case of replacement of primary identical spherical particles on porous spheres.Рассмотрены возможности применения моделирования для развития двух перспективных направлений современного наноматериаловедения: материалов с иерархией пор, собранных посредством иерархической самосборки, а также иерархических структур из нанопористых  элементов. С использованием квазидвумерной проекции трехмерного детерминированного  фрактального агрегата Жюльена оценен размер пор в иерархических структурах. Трехмерное  моделирование иерархических структур, организованных посредством самосборки наносфер,  проведено в среде Autodesk 3ds Max. Проанализированы зависимости пористости, плотности,  удельной площади поверхности фрактальных структур от размеров агрегатов (при  возникновении новых уровней пор иерархических материалов), а также изменения пористости при замене первичных идентичных сферических частиц на пористые сферы

Photoluminescence and its damping kinetics of nanoporous alumina m embranes formed in solutions of various carboxylic acids

The article is devoted to the study of the photoluminescence of carbon-containing anodic alumina obtained in various electrolytes based on carboxylic (tartaric and oxalic) acids. We studied the emission and excitation spectra of luminescence, as well as the PL decay of nanostructured anodic alumina membranes. It is shown that such membranes exhibit photoluminescence (excitation wavelength 330 nm) in the wavelength range 350-600 nm with a maximum at 460 nm. They have two PL centers with maxima at 440 and 490 nm and lifetimes of 0.2 and 4.0 ns, respectively. It is shown that the PL peak at 440 nm can be related to the emission of COO– - ions, and the peak at 490 nm can be related to the PL of defects in partially oxidized amorphous carbon

The sorption of water molecules in the pores of anodic alumina films during aluminum anodizing in oxalic acid

The thermogravimetric analysis of membranes of anodic aluminum oxide (AAO) was carried out. The results showed that in the process of anodic growth, water molecules are adsorbed in the pores of Al2O3, the amount of which is determined by the anodizing voltage of aluminum. The relationship is revealed and the graphs of the relationship between anodizing voltage, annealing temperature, and weight loss of nanostructured membranes of AAO are presented. It has been established that the adsorption of water molecules on the surface of AAO is explained by the presence of a surface charge, which disappears after annealing at 200–300 °C. An increase in the amount of adsorbed water with an increase in the anodizing voltage from 20 to 40 V indicates a decrease in the surface charge density

Results from the Indo-USSR ozonesonde intercomparison experiment

A total of seventeen vertical profiles of ozone were obtained during an Indo-USSR collaborative experiment on ozonesonde intercomparison conducted at Thumba during March 1983. The vertical distribution of ozone was measured using rocket-borne, balloon-borne as well as ground-based instruments. Four different rocket ozonesondes from India and USSR and the balloon ozonesonde were used to makein situ observations of ozone concentrations in addition to the Dobson spectrophotometric observations of total ozone and Umkehr. The rocket and the balloon launchings were effected in three salvos and measurements were made at different times of the day as well as during night. The results of all these measurements are used to obtain a mean ozone vertical distribution over Thumba foT the spring equinoxial period. The mean profile shows the maximum ozone concentration at 27 km with a value of (3.86±0-52)×1012 molecules per cc. Comparison of this mean profile with available satellite data for the equatorial regions shows that, in general, the Thumba values are lower by 10–15% at altitudes below 40 km and larger at altitudes above 50 km compared to the satellite results. The data also show evidence for a day-to-day variability and a possible day-to-night variability in the ozone vertical distribution with the night-time values higher than the daytime values at all altitudes above 35 km and the difference is found to increase with the increasing altitude

Исследование тепловых характеристик нагревательного элемента из алюминия с нанопористым оксидом алюминия

In this work, we studied the thermal characteristics of flat heaters made of aluminum with a strip heating element in the form of carbon fiber. In order to provide the necessary insulation of the heating element from the metal base, a layer of porous anodic aluminum oxide with a thickness of 20 μm was formed on the aluminum surface. The ends of the carbon fiber filament were metallized with a layer of copper for subsequent soldering during the assembly of the electric heater. The carbon fiber filament of electric heater had an electrical resistance of 60 Ohms. Studies of the propagation of heat fluxes in the volume of a board made of aluminum with nanoporous aluminum oxide were carried out using thermal imaging measurements. The paper presents the dependence of temperature changes on the surface of the lid of a heating element made of aluminum and on the opposite side — heat transfer side with heating time. The results showed that the heat generated by a linear heating element of carbon fiber, quickly distributed throughout the entire volume of the aluminum plate of the heating element. This indicates a high thermal conductivity of the aluminum base of the heater, the parameters of which allow to achieve the required thermal characteristics of the heater.Одной из актуальных задач в сфере стационарного отопления, на решение которой направлены усилия многочисленных разработчиков, является экономия электрической энергии. Нагревательные системы могут иметь самые разнообразные конструкции, но существуют основные требования к их разработке, а именно: обеспечение высокой надежности при эксплуатации, экономичность, устойчивость к внешним воздействиям и стабильность электрических характеристик. Основной элемент любого нагревательного устройства — нагреватель. В настоящее время плоские резистивные нагреватели нашли широкий спектр применения в нагревательных устройствах, предназначенных для формирования здорового микроклимата в помещениях, поддержания заданных параметров в различных технологических процессах, в системах антиобледенения, в сельском хозяйстве и в промышленности. Исследованы тепловые характеристики плоских нагревателей, изготовленных из алюминия, с ленточным элементом нагрева в виде углеродного волокна. С целью обеспечения необходимой изоляции нагревательного элемента от металлического основания на поверхности алюминия формировали слой пористого анодного оксида алюминия толщиной 20 мкм. Концы нити из углеродного волокна металлизировали слоем меди для последующей пайки в процессе сборки электрического нагревателя. Электрическое сопротивление нагревателя с нитью из углеродного волокна составляло 60 Ом. Исследования распространения тепловых потоков в объеме платы из алюминия с нанопористым оксидом алюминия проводили с использованием тепловизионных измерений. Представлена зависимость изменения температуры на поверхности крышки нагревательного элемента из алюминия и на противоположной теплоотдающей стороне от времени нагрева. Полученные результаты показали, что тепло, генерируемое линейным нагревательным элементом из углеродной нити, быстро перераспределятся по всему объему алюминиевой пластины с нагревательным элементом. Это свидетельствует о высокой теплопроводности алюминиевой основы нагревателя, параметры которой позволяют обеспечить достижение требуемых тепловых характеристик нагревателя

Influence of Electrolyte Temperature on the Formation of the Morphology of the Porous Structure of Anodic Aluminum Oxide

The results of research on anodizing thin aluminum films 100 nm thick on SiO2–Si plates at 30 V in a 0.3 M aqueous solution of oxalic acid are presented. The effect of the electrolyte temperature on the morphology of porous anodic aluminum oxide (PAAO) films is studied. The pore diameter and interpore distance are determined by the computer analysis of the SEM images of the morphology of the anode films using the ImageJ software. The data obtained show that the pore diameter does not depend on the temperature of the electrolyte and the time of the process, but is determined only by the anodizing voltage. In the electrolyte temperature range of 5 to 40°C, the pore diameter of the PAAO films is 20 ± 0.5 nm, and the interpore distance is 77.7 nm. The research results indicate that a change in the temperature of the electrolyte, in contrast to the anodizing voltage, affects only the growth rate of the anode film, and not its porous morphology