Distribution of the residual tritium content in organs of <Emphasis Type="Italic">Carassius gibelio</Emphasis> (Prussian carp) freshwater ray-finned fish

The distribution of residual tritium in organs of Carassius gibelio (Prussian carp) freshwater rayfinned fish as a representative of the Carassius phytophagous genus of Cyprinidae family was studied for determining the ³Н accumulation in the aquatic plants–fishes food chain in water bodies contaminated with radionuclides. In the first step, tritium was accumulated by 3000 g (wet weight) of the aquatic plant biomass in aquaria of 100 L volume with the specific water activity of 100 kBq L^–1. The aquatic plants were shown to actively take up the introduced tritium, accumulating up to 70% of the radionuclide. The content of tritium bound to organics in the biomass increased to 21% of the whole accumulated tritium. After that, the plants (Ceratophyllum, Lemna) were dried and mixed with dry fish fodder (1: 1), and the mixture was pressed in granules. The activity of each granule was up to 50 Bq. These granules were used for forced feeding of fishes, so that each individual took up in the course of the 550-day experiment up to 330 kBq of tritium. According to the analysis results, about 75% of the whole amount of the accumulated tritium was present in muscle tissues. Determination of the tritium content of proteins and lipids in the experimental systems revealed no differences in the use of Ceratophyllum and Lemna as fodder.     

Forecasting Capillary Characteristics for Aluminum Nitride Ceramic ― Liquid Metal Systems

A test has been devised that allows one to determine the work of adhesion and wettability in a system composed of aluminum nitride ceramics with a liquid metal without the need for experimental examination. A correlation is examined between the work of adhesion on the one hand and that criteria or others on the other that have been proposed by various researchers. Forecasts are made for the work of adhesion and wetting angle for a series of metals that have not been examined previously. An experimental check has been made on the forecast adhesion activity for some elements.     

Physicochemical characteristics of adsorbents based on coals from the Khar Tarvagatai deposit in Mongolia

The results of a study of the physicochemical characteristics of porous carbon materials prepared based on low-metamorphosed black coal from the Khar Tarvagatai deposit in Mongolia are presented in this article. The carbon material synthesized with the use of an alkaline impregnation method corresponds to uniformly porous, predominantly, microporous (to 70% of micropores in terms of adsorption volume) sorbents with a specific surface area of ～1100 m²/g. The use of additional ozonolytic activation of the sorbent facilitated an insignificant decrease in its porosity with an increase in the number of oxygen groups on the sample surface by a factor of 2.5 in this case.     

Pore structures of carbon materials based on naturally oxidized Kuzbass coals

Carbon materials prepared by the thermolysis of naturally oxidized Kuzbass coals of different ranks in the presence of potassium hydroxide at a KOH/coal weight ratio of 1 g/g were studied with the use of X-ray diffraction analysis and porosimetry. It was found that porous carbon materials with a developed specific surface area and a specific pore volume with the contribution of micropores from 35 to 70% were formed upon chemical activation with KOH regardless of selected precursors.     

An iron-based T 1 contrast agent made of iron-phosphate complexes: In vitro and in vivo studies

A new iron-based T ₁ contrast agent consisting of a complex of iron ions coordinated to phosphate and amine ligands (Fe_(phos) in short) has been characterized by spectroscopic and magnetic measurements. NMR relaxation studies showed r ₁ values to be dependent on the phosphate salt concentration, K₂HPO₄, present in the medium. r ₁ reaches a maximum value of 2.5 mM^?1 s^?1 for measurements carried out at 7 T and 298 K. ³¹P MRS, Mössbauer spectroscopy and magnetic measurements of Fe_(phos) solutions suggest paramagnetic Fe³⁺ ions present in the studied iron–phosphate complex. In vitro and in vivo toxicity experiments with C6 cells and CD1 mice, respectively, demonstrated lack of toxicity for Fe_(phos) at the highest dose tested in the MRI experiments (12 mM iron for C6 cells and 0.32 mmol iron/kg for mice). Finally, T ₁ weighted images of brain tumours in mice have shown positive contrast enhancement of Fe_(phos) for tumour afflicted regions in the brain.     

Power transmission line operating modes calculation with controllable phase shifters

The article contains the analysis of the influence of the phase shifter (PS) on the energy processes in the power transmission line in terms of the two-unit model of the electric network. The approach to synthesis of the models regulated by the phase shifter providing for both calculation of the steady operation modes of the electric networks with the phase shifters and research of the electromagnetic processes and designing of the device itself is offered.     

Intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by redistribution of hydrogen between the units

The dehydrogenation and dewaxing of hydrocarbons of middle-distillate fractions, which proceed in the hydrogen medium, are of great importance in the petrochemical and oil refining industries. They increase oil refining depth and allow producing gasoline, kerosene, and diesel fractions used in the production of hydrocarbon fuels, polymer materials, synthetic detergents, rubbers, etc. Herewith, in the process of dehydrogenation of hydrocarbons of middle distillate fractions (C₉–C₁₄) hydrogen is formed in the reactions between hydrocarbons, and the excess of hydrogen slows the target reaction of olefin formation and causes the shift of thermodynamic equilibrium to the initial substances. Meanwhile, in the process of hydrodewaxing of hydrocarbons of middle distillate fractions (C₅–C₂₇), conversely, hydrogen is a required reagent in the target reaction of hydrocracking of long-chain paraffins, which ensures required feedstock conversion for production of low-freezing diesel fuels. Therefore, in this study we suggest the approach of intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by means of redistribution of hydrogen between the two units on the base of the influence of hydrogen on the hydrocarbon transformations using mathematical models. In this study we found that with increasing the temperature from 470 °C to 490 °C and decreasing the hydrogen/feedstock molar ratio in the range of 8.5/1.0 to 6.0/1.0 in the dehydrogenation reactor, the production of olefins increased by 1.45–1.55%wt, which makes it possible to reduce hydrogen consumption by 25,000 Nm³/h. Involvement of this additionally available hydrogen in the amount from 10,000 to 50,000 Nm³/h in the dewaxing reactor allows increasing the depth of hydrocracking of long-chain paraffins of middle distillate fractions, and, consequently improving low-temperature properties of produced diesel fraction. In such a way cloud temperature and freezing temperature of produced diesel fraction decrease by 1–4 °C and 10–25 °C (at the temperature of 300 °C and 340 °C respectively). However, when the molar ratio hydrogen/hydrocarbons decreases from 8.5/1.0 to 6.0/1.0 the yield of side products in the dehydrogenation reactor increases: the yield of diolefins increases by 0.1–0.15%wt, the yield of coke increases by 0.07–0.18%wt depending on the feedstock composition, which is due to decrease in the content of hydrogen, which hydrogenates intermediate products of condensation (the coke of amorphous structure). This effect can be compensated by additional water supply in the dehydrogenation reactor, which oxidizes the intermediate products of condensation, preventing catalyst deactivation by coke. The calculations with the use of the model showed that at the supply of water by increasing portions simultaneously with temperature rise, the content of coke on the catalyst by the end of the production cycle comprises 1.25–1.56%wt depending on the feedstock composition, which is by 0.3–0.6%wt lower that in the regime without water supply.     

Morphological features of porous silicon carbide obtained via a carbothermal method

Samples of porous silicon carbide were obtained using sucrose or carbon and aerosil or silica mesoporous molecular sieves (SBA‐3, SBA‐15, KIT‐6 and MCF). Fibers content in silicon carbide samples is higher when the mesopore surface area of carbon materials derived from carbon‐silica composites is lower. Based on the found correlation between the morphology and porosity of SiC and mesopore surface area of the carbon component in the composites, a templating action of carbon in carbothermal reduction was suggested.