Account of diffusion in local thermodynamic equilibrium and two-temperature plasma models

A self-consistent account of the effect of diffusion on charge transport in local thermodynamic equilibrium (LTE) and two-temperature (2T) ionization-equilibrium plasmas amounts to introducing into Ohm’s law, in addition to the conventional term proportional to the electric field (conduction current) and thermal-diffusion terms, also terms describing the diffusion due to plasma composition variations, which are proportional to the temperature gradient (or, in the case of 2T plasmas, to ∇Te and ∇Th) and to the plasma pressure gradient. These terms are calculated, with the use of the Stefan–Maxwell equations, for the particular case of 2T ionization-equilibrium atomic plasmas with singly charged ions. Also proposed is a simple way of approximate evaluation of reactive thermal conductivity in such plasmas. An online tool performing evaluation of the relevant coefficients for 2T argon, xenon, and mercury plasmas has been deployed on the internet. Representative modelling results show that the new form of Ohm’s law, when introduced into standard LTE or 2T models, may describe the electric field reversal in front of arc anodes, an effect that has been simulated previously only by means of (more complex) models taking into account deviations from ionization equilibrium.info:eu-repo/semantics/publishedVersio

Somatoform disorders in the family doctor's practice.

Somatoform disorders – psycho­genic diseases are characterized by pathological physical symptoms that resemble somatic illness. Thus, any organic manifestations, which can be attributed to known diseases are not detected, but there are non-specific functional impairments. Somatoform disorders include somatization disorder, undifferentiated somatoform disorder, hypocho­n­driacal disorder, somatoform dysfunction of the autonomic nervous system and stable somatoform pain disorder. The first part of the article reviewes features of the clinical manifestations of somatization disorder and undifferentiated somatoform disorder. Role of non-benzodiazepine tranquilizers (ADAPTOL) and metabolic drugs (VASONAT) in the treatment of patients with somatoform disorders is discussed. In review article data of neurologists and cardiologists on the effectiveness of anxiolytic drug ADAPTOL and metabolic drug VASONAT in different clinical groups of patients (coronary artery disease, chronic ischemia of the brain), which can significantly improve quality of life, increase exercise tolerance, improve cognitive function and correct mental and emotional disorders are presented

Numerical modelling of high-pressure arc discharges: matching the LTE arc core with the electrodes

A widely used approach to simulation of high-pressure arc discharges is based on the system of magneto-hydrodynamic equations written in the approximation of local thermodynamic equilibrium (LTE). In this work, boundary conditions on the surface of the electrodes are formulated with the use of equations of balance of energy in the non-equilibrium near electrode layers that separate the LTE bulk plasma and the electrodes. As an example, numerical simulations of a free-burning arc in atmospheric-pressure argon plasma in the current range from 20 to 200 A are reported. Simulation results are in reasonably good agreement with those given by more sophisticated models and with the experiment. Simulations performed for cathodes of slightly different geometries have predicted a strong effect produced by details of the cathode geometry over the distribution of the current density along the cathode surface and therefore over the plasma temperature, an interesting and potentially important result that is worth further numerical investigation and experimental verification.info:eu-repo/semantics/publishedVersio

Numerical investigation of AC arc ignition on cold electrodes in atmospheric-pressure argon

Since experiments cannot clarify the mechanism of current transfer to non-thermionic arc cathodes, this can only be done by means of numerical modelling based on first principles and not relying on a priori assumptions. In this work, the first quarter-period after the ignition of an AC arc on cold electrodes in atmospheric-pressure argon is investigated by means of unified one-dimensional modelling, where the conservation and transport equations for all plasma species, the electron and heavy-particle energy equations, and the Poisson equation are solved in the whole interelectrode gap up to the electrode surfaces. Results are compared with those for DC discharges and analysed with the aim to clarify the role of different mechanisms of current transfer to non-thermionic arc cathodes. It is found that the glow-to-arc transition in the AC case occurs in a way substantially different from the quasi-stationary glow-to-arc transition. The dominant mechanisms of current transfer to the cathode during the AC arc ignition on cold electrodes are, subsequently, the displacement current, the ion current, and thermionic emission current. No indications of explosive emission are found. Electron emission from the impact of excited atoms can hardly be a dominant mechanism either. The introduction of the so-called field enhancement factor, which is used for description of field electron emission from cold cathodes in a vacuum, leads to computed cathode surface temperature values that are appreciably lower than the melting temperature of tungsten even in the quasi-stationary case. This means that pure tungsten cathodes of atmospheric-pressure argon arcs can operate without melting, in contradiction with experiments.info:eu-repo/semantics/publishedVersio

Interaction of a free burning arc with regenerative protective layers

The possible use of protective layers made of ceramic powders for walls in thermal plasma applications is studied. A stable free burning arc of currents up to 5 kA between copper- tungsten electrodes is used to analyse the arc interaction with samples coated by mixtures of CaCO3, MgCO3, and Mg(OH)2 with plaster. By means of optical emission spectroscopy the maximum arc temperature and the radiation impact on the surfaces are estimated to be around 15000 K and 20 MWm-2, respectively. Thermographic measurements confirm the efficient protection of substrates by all layer materials. Layers containing CaCO3 lead to the lowest heating of ceramic samples which may be caused by a strong evaporation of the layer material

Kinetic study of carbon dioxide catalytic methanation over cobalt–nickel catalysts

Based on the data of the thermoprogrammed desorption and using mass-spectroscopic analysis of desorbed products and on the kinetic patterns of the methanation process for cobalt–nickel catalysts, we suggested a mechanism for the reaction which passes through forming intermediate formyl compounds: CHO*, HCOH*, and HCOOH*. Because of the high stability of the carbon dioxide molecule, the step of adding the first hydrogen atom is the limiting step. Such a mechanism is in good agreement with the proposed kinetic equations

Numerical and experimental study of arc fault in aeronautical conditions

The use of electrical energy is constantly increasing in airplanes. This concerns needs in motor, actuators or those related to services for example. Naturally the electric energy-related risks increase. Arc discharges can appear with consequences that can be dramatic. The electrical constraints to which a plane is subject are not only internal. The aircraft are also regularly struck by lightning in-flight. Composite materials, increasingly used, make more difficult the management of these risks of lightning strikes. So the arc discharge is a concern in the aeronautical domain. This specific area imposes special conditions that do not exist in other areas where the arcs are present. Our intervention is intended to present these studies, with in the rest of this paper, references to two specific topics, the arc fault in the electric core of aircraft and damage to the composite by structure being struck by lightning

Numerical and experimental study of arc fault in aeronautical conditions

The use of electrical energy is constantly increasing in airplanes. This concerns needs in motor, actuators or those related to services for example. Naturally the electric energy-related risks increase. Arc discharges can appear with consequences that can be dramatic. The electrical constraints to which a plane is subject are not only internal. The aircraft are also regularly struck by lightning in-flight. Composite materials, increasingly used, make more difficult the management of these risks of lightning strikes. So the arc discharge is a concern in the aeronautical domain. This specific area imposes special conditions that do not exist in other areas where the arcs are present. Our intervention is intended to present these studies, with in the rest of this paper, references to two specific topics, the arc fault in the electric core of aircraft and damage to the composite by structure being struck by lightning

Вплив кадмієвого навантаження на активність ензимної ланки глутатіонової системи організму бугайців

One of the ultimate manifestations of Cadmium's toxic effects is the depletion of the animal's antioxidant protection system. The article presents data on the effect of cadmium chloride at a dose of 0.04 mg/kg body weight on the activity of enzymes of the glutathione system of antioxidant protection of the body of young cattle. The surveys were conducted on the basis of farm Ivanivtsi of Zhydachiv district of Lviv region on 10 bulls of six months old, Ukrainian black-ruffed dairy breed, which were formed into 2 groups of 5 animals each: control and experimental. Bulls of the experimental group were fed with feed cadmium chloride at a dose of 0.04 mg/kg body weight of the animal. For research, the rules were compulsory for performing zootechnical experiments on the selection and retention of analogues in groups, technology for the procurement, use and accounting of feed consumed. The diet of the animals was balanced by the nutrients and minerals that provided for their need for essential nutrients. The results of studies indicate that Cadmium significantly affects the metabolism processes in liver cells, and thus stimulates lipid peroxidation processes and inhibits the activity of enzymes of the glutathione link of the antioxidant system. The lowest activity of the enzyme link of the glutathione system of antioxidant protection of the body of cattle was found on the twentieth day of the experiment, where, accordingly, the activity of glutathione peroxidase in the serum of bugs of the experimental group decreased by 22.6%, the activity of glutathione 6 phosphate dehydrogenase – by 24.3% relative to the control group of animals. The inhibition of the activity of enzymes of the glutathione system of the organism of bulls of the experimental group is caused by the development of oxidative stress caused by the feeding of Cadmium. The researches made it possible to reveal more deeply the pathogenesis of the toxic effect of cadmium on the body of bugs and use these data in the development of an antidote for cadmium intoxication.Одним з кінцевих проявів токсичної дії Кадмію є виснаження системи антиоксидантного захисту організму тварин. У статті наведені дані щодо впливу кадмію хлориду у дозі 0,04 мг/кг маси тіла тварини на активність ензимів глутатіонової системи антиоксидантного захисту організму молодняку великої рогатої худоби. Дослідження проводились на базі фермерського господарства с. Іванівці Жидачівського району Львівської області на 10 бугайцях шестимісячного віку, української чорно-рябої молочної породи, які були сформовані у 2 групи по 5 тварин у кожній: контрольну та дослідну. Бугайцям дослідної групи згодовували з кормом кадмію хлорид у дозі 0,04 мг/кг маси тіла тварини. Для проведення досліджень дотримувалися правил, обов’язкових з виконання зоотехнічних дослідів щодо підбору та утримання тварин-аналогів у групи, технології заготівлі, використання й обліку спожитих кормів. Раціон тварин був збалансований за поживними та мінеральними речовинами, які забезпечували їх потребу в основних елементах живлення. Результати досліджень вказують на те, що Кадмій істотно впливає на процеси метаболізму в клітинах печінки і таким чином стимулює процеси перекисного окиснення ліпідів та пригнічує активність ензимів глутатіонової ланки антиоксидантної системи. Найнижчу активність ензимної ланки глутатіонової системи антиоксидантного захисту організму молодняку великої рогатої худоби виявляли на двадцяту добу досліду, де відповідно активність глутатіонпероксидази у сироватці крові бугайців дослідної групи знизилася на 22,6%, активність глутатіонредуктази – на 22,5% та активність глюкозо-6-фосфатдегідрогенази – на 24,3% щодо показників контрольної групи тварин. Пригнічення активності ензимів глутатіонової системи організму бугайців дослідної групи зумовлене розвитком оксидаційного стресу, викликаного згодовування Кадмію. Проведені дослідження дали можливість глибше розкрити патогенез токсичної дії Кадмію на організм бугайців та використати ці дані при розробці антидоту при кадмієвій інтоксикації

Research in the area of preparing activated alumina. Part 4. new technological approaches for synthesis of ultrafine α-Al₂O₃

Results of new integrated technological approaches to synthesis of ultrafine -alumina using commercially available metallurgical alumina as a raw material are presente