Влияние условий осаждения из паров металлоорганических соединений на получение эпитаксиальных слоев n-CdTe с использованием изопропилиодида

The dependence of iodine incorporation in CdTe layers on the deposition conditions during metalorganic vapor phase epitaxy is investigated. The growth of the layers was carried out from dimethylcadmium and diethyltellurium in the hydrogen flow in a vertical reactor with a hot wall condition at a total pressure of 20 kPa. The total iodine concentration was determined by secondary ion mass spectrometry, the electrically active concentration was determined from the Hall effect measurement. The iodine incorporation depends on the crystallographic orientation of the substrate (were studied (100), (310), (111)A, (111)B, (211)A and (211)B), the concentration of the doping precursor (flux range 5·10–8–3·10–6 mol/min), the mole ratio of organometallic compounds (DMCd/DETe=0.25–4), growth temperature (335–390°C) and the walls of the reactor above the pedestal (hot wall zone 290–320°C). The total iodine concentration reached 5·1018 cm–3 and the activation efficiency was ~4 %. After thermal annealing in cadmium vapor at 500°C the activation efficiency was ~100 %.

Comparison of the Accelerated and Spontaneous Deactivation of the HDS Catalyst

Owing to the increased use of secondary materials for diesel production, refineries must confront bad quality parameters. Therefore, catalysts with certain capabilities (to remove heteroatoms and improve quality parameters at low hydrogen consumption) and their lifetimes are required. An important parameter that influences the quality of the products and the economy of the unit is the activity of the catalyst. Prior to industrial use, the catalyst is typically tested in a pilot unit. This is necessary to obtain a considerable amount of data on the lifetime of the catalyst in the shortest feasible time. Here, deactivation steps were used to test the catalyst. Two experiments were performed to evaluate the effect of two types of accelerated deactivations on the catalyst activity and product properties. The first type of deactivation proceeded for 6 h and comprised a tripling of the amount of incoming feedstock, and the second type proceeded for 18 h without an increase in the amount of feedstock. For both cases, the pressure and hydrogen flow were minimised. Both types of accelerated deactivations had similar effects on the quality of the final products and catalyst. The only difference was in the duration of catalyst recovery after deactivation. The results were compared with those of a test in which the spontaneous deactivation of the catalyst was studied.

Experimental Assessment of Perhydro-Dibenzyltoluene Dehydrogenation Reaction Kinetics in a Continuous Flow System for Stable Hydrogen Supply

The development of alternate clean energy resources is among the most pressing issues in the energy sector in order to preserve the global natural environment. One of the ideal candidates is the utilization of hydrogen as a primary fuel in lieu of fossil fuels. It can be safely stored in liquid organic hydrogen carrier (LOHC) materials and recovered on demand. A uniform supply of hydrogen is essential for power production systems for their smooth operation. This study was conducted to determine the operating conditions of the dehydrogenation of perhydro-dibenzyltoluene (H18-DBT) to ensure that hydrogen supply in a continuous flow reactor remains stable over a wide range of temperatures. The hydrogen flow rate from the dehydrogenation reaction was measured and correlated with the degree of dehydrogenation (DoD) evaluated from the refractive index of reactant liquid samples at various temperatures, WHSV and the initial reactant concentrations. Moreover, a kinetic model is presented holding validity up to a WHSV of 67 h−1. The results acquired present a range for an order of reaction from 2.3 to 2.4 with the required activation energy of 171 kJ/mol.

Numerical Simulation of Erosion Characteristics for Solid-Air Particles in Liquid Hydrogen Elbow Pipe

The crystalline solid-air in the liquid hydrogen will cause erosion or friction on the elbow, which is directly related to the safety of liquid hydrogen transportation. The CFD-DPM model was used to study the erosion characteristics of solid-air to liquid hydrogen pipelines. Results show that the outer wall of the cryogenic liquid hydrogen elbow has serious erosion in the range of 60–90°, which is different from the general elbow. The erosion rate is linearly positively correlated with the mass flow of solid-air particles, and the erosion rate has a power function relationship with the liquid hydrogen flow rate. The fitted relationship curve can be used to predict the characteristics and range of the elbow erosion. The structure of the liquid hydrogen elbow also has an important influence on the solid-cavity erosion characteristics. The increase of the radius of curvature is conducive to the reduction of the maximum erosion rate, while the average erosion rate undergoes a process of increasing and then decreasing. The radius of curvature is 60 mm, which is the inflection point of the average erosion rate of the 90° elbow. The research results are expected to provide a theoretical basis for the prevention of liquid hydrogen pipeline erosion.

Variation of the Number of Heat Sources in Methane Dry Reforming: A Computational Fluid Dynamics Study

To overcome the weak point of the gas type heating (failure in heating uniformly and persistently), liquid type molten salt as a concentration of solar energy was considered as a heat source for dry reforming. This high-temperature molten salt flowing through the center of the tubular reactor supplies necessary heat. The dependence on the number of heat source of the hydrogen production was investigated under the assumption of the fixed volume of the catalyst bed. By changing these numbers, we numerically investigated the methane conversion and hydrogen flow rate to find the best performance. The results showed that the methane conversion performance and hydrogen flow rate improved in proportion to the number of heating tubes. For the one heat source, the reactor surrounded by a heat source rather than that located in the center is the best in terms of hydrogen yield. In addition, this study considered the case in which the system is divided into several smaller reactors of equal sizes and a constant amount of catalyst. In these reactors, we saw that the methane conversion and hydrogen flow rate were reduced. The results indicate that the installation of as many heating tubes as possible is preferable.

ENRICHMENT OF THE DIET OF BULLS WITH IRON

Изучено влияние обогащения рациона бычков калмыцкой породы наноразмерными частицами микроэлементов в составе ультрадисперсных порошков металлов на мясное сырье. Нанопорошок железа получен химико-металлургическим способом низкотемпературного восстановления в потоке водорода гидроксидов и оксидов железа в ультрадисперсном состоянии до наночастиц с последующей пассивацией. По принципу пар-аналогов сформировали 2 группы бычков по 12 голов ― контрольную и опытную с живой массой молодняка, соответственно, 175,5±7,5 и 173,5±5,2 кг. Введение в рацион добавки, содержащей 0,08 мг железа на 1 кг живой массы в состав комбикорма для бычков на откорме в возрасте 6―18 мес путем его опрыскивания, позволило обогатить мышечную ткань животных эссенциальным железом, улучшить нутриентный состав говядины для детского и функционального питания. Установлено возрастное увеличение содержания общего белка в сыворотке крови бычков в контроле ― от 79,0±1,4 г/л в 6 мес до 85,0±1,1 в 18 мес и в опытной группе ― от 80,0±1,4 до 86,0±1,1 г/л соответственно. Количество альбуминов с возрастом увеличивалось: в контроле ― от 48,01±1,05 г/л в 6 мес до 52,03±1,10 в 18 мес и в опытной группе ― от 49,02±1,14 г/л в 6 мес до 52,02±1,13 г/л в 18 мес. Установлено двукратное повышение содержания железа в длиннейшей мышце туш опытных бычков, которое составило 89,29 мг/кг железа. Установлена возможность прижизненного обогащения говядины железом более, чем в 2 раза. The influence of enriching the diet of Kalmyk gobies with nanosized particles of microelements in the composition of ultra-dispersed metal powders meat raw materials has been studied. Iron nanopowder was obtained by the chemical-metallurgical method of low-temperature reduction in a hydrogen flow of hydroxides and iron oxides in an ultradispersed state to nanoparticles with subsequent passivation. According to the principle of analog pairs, 2 groups of gobies 12 heads each were formed ― control and experimental ― with the live weight of young animals, respectively, 175.5±7.5 and 173.5±5.2 kg. The introduction into the diet of an additive containing 0.08 mg of iron per 1 kg of live weight in the composition of feed for fattening bulls at the age of 6―18 months by spraying it, made it possible to enrich the muscle tissue of animals with essential iron, improve the nutrient composition of beef for baby and functional nutrition. An age-related increase in the concentration of total protein in the blood serum of gobies in the control was determined ― from 79.0±1.4 g/l at 6 months to 85.0±1.1 g/l at 18 months and in the experimental group ― from 80.0±1.4 to 86.0±1.1 g/l, respectively. The number of albumin increased with the age: in the control ― from 48.0±1.17 g/l at 6 months to 52.0±1.19 g/l at 18 months and in the experimental group ― from 49.0±1.16 g/l at 6 months to 52,0±1.18 g/l at 18 months A twofold increase in the iron content in the longest muscle of the back of experimental gobies was determined, which amounted to 89.29 mg/kg of iron. The possibility of in vivo enrichment of beef with iron by more than 2 times has been determined.

Evolution of Unidirectional Solidification Microstructure and Hydrogenated Treatment of Nb-Ti-Co Quasiperitectic Alloys

Titanium alloys have a wide range of applications, and the internal placement of hydrogen into them can modulate the microstructure of the alloys and thus have great potential for further development. However, few studies have been reported on the application of this technique to Nb-Ti-Co ternary alloys, which needs to be urgently investigated. In this paper, four types of alloys (Nb10Ti61Co29, Nb15Ti55Co30, Nb20Ti50Co30, and Nb25Ti50Co25) are selected near the eutectic point of the phase diagram to study their placement of hydrogen by both static and dynamic processes of hydrogen’s placements, focusing on the effects of the temperature, time, and hydrogen-flow rate of such processes on the amount of hydrogen placements. The relationship between the hydrogen replacement parameters and the mechanical properties of the alloys is constructed. The results show that the placed-hydrogen amount of Nb-Ti-Co as-cast alloy grows with the increase of hydrogen-flow rate and soaking (or holding) time, with an upper limit of the placed-hydrogen amount, and the pattern of the directionally- solidified alloys is similar to that of the as-cast alloys; however, at a certain soaking time and hydrogen- flow rate, although the placed hydrogen amount of both alloys rises with the increase of temperature, the placed-hydrogen amount of Nb-Ti-Co directionally-solidified alloys is always larger than that of the as-cast alloys. However, the amount of hydrogen placement in the Nb-Ti-Co directionally-solidified alloys is always larger than that in the as-cast alloys, and the amount of hydrogen placement decreases significantly as the growth rate of the alloys increases. In addition, the microhardness decreases with increasing growth rate in the directionally-solidified specimens, and the amount of hydrogen placement and microhardness increase with growing Nb content.