The homogeneous stirred reactor designed for kinetic studies of the combustion of hydrocarbons with intensive internal recirculation in high temperature combustion chamber is described. The originality of our reactor lies in its construction which allows to intensively mix fuel and flue gases, measure gas temperature as well as obtain samples which can be used to investigate diffusion flames. The cylindrical construction enables to use the reactor in laboratory cylindrical electrically heated ovens. The CFD analysis of the reactors, the mixing parameters (turbulent Peclet number and mixing level) and the volume average temperature in the reactors were elaborated on the basis of the typical dimensions of classical reactors to kinetics research as well as the own reactor design. The results of the analysis allow to reveal advantages of our construction.
Polish energy security is currently one of the key elements affecting the national security system. Maintaining operational efficiency and the permanent modernization of both, power plants, as well as transformer stations and transmission networks is a starting point of ensuring energy security in our country. This is a significant challenge, taking into account the age of the energy critical infrastructure elements in Poland, as well as the permanent increase of the demand for electricity. This implies a systematic growth of the importance of the issue the country’s energy security. The numerous events and anomalies that accompany our everyday life, such as the storms that passed over Poland on the night of August 11–12, 2017, indicate the considerable sensitivity of the critical energy infrastructure on the impact of various negative factors. The security of Polish critical infrastructure connected with the distribution of electricity is particularly at risk. Therefore, it is desirable not only for current repairs and the modernization of the power system elements, but also for the work related to adapting the infrastructure to current and even forecasted needs, challenges and threats. In the face of the presented research results, the reconstruction of the Polish power system, as well as the implementation of innovative solutions in the production, transmission and distribution of energy seems to be unavoidable. Therefore interdisciplinary research and analyses are recommended, allowing the level security of the critical infrastructure to be increased through the best possible diagnosis of factors that may even slightly threaten this security.
Hass avocado cultivation in Colombia has grown rapidly in area in recent years. It is being planted in marginal areas, which leads to low yields, and in many cases is related to diseases. Ecological niche modeling (ENM) can offer a view of the potential geographic and environmental distribution of diseases, and thus identify areas with suitable or unsuitable conditions for their development. The aim of the study was to assess current and potential distribution of the major diseases on Hass avocado in Colombia. Areas planted with Hass avocado in Antioquia, Colombia were sampled for diseases including the following pathogens: Phytophthora cinnamomi, Verticillium sp., Lasiodiplodia theobromae, Phytophthora palmivora, Colletotrichum gloeosporioides sensu lato, Pestalotia sp., and Capnodium sp., and one disorder hypoxia-anoxia. These pathogens were selected based on their relevance (incidence-severity) and capacity to cause damage in different tissues of avocado plants. Severity and incidence of each disease were related to environmental information from vegetation indices and topographic variables using maximum entropy modeling approaches (MaxEnt). Models were calibrated only across areas sampled, and then transferred more broadly to areas currently planted, and to potential zones for planting. Combinations of best performance and low omission rates were the basis for model selection. Results show that Hass avocado has been planted in areas highly conducive for many pathogens, particularly for Phytophthora cinnamomi and hypoxia-anoxia disorder. Ecological niche modeling approaches offer an alternative toolset for planning and making assessments that can be incorporated into disease management plans.
The paper presents methods of on-line and off-line estimation of UAV position on the basis of measurements from its integrated navigation system. The navigation system installed on board UAV contains an INS and a GNSS receiver. The UAV position, as well as its velocity and orientation are estimated with the use of smoothing algorithms. For off-line estimation, a fixed-interval smoothing algorithm has been applied. On-line estimation has been accomplished with the use of a fixed-lag smoothing algorithm. The paper includes chosen results of simulations demonstrating improvements of accuracy of UAV position estimation with the use of smoothing algorithms in comparison with the use of a Kalman filter.
In the paper, on the basis of our studies and the available literature data, a model of changes in the number of active centers corresponding to the structure of the reactive coal particle has been developed. A new distribution function that links the specific surface area of a particle with its porosity and reaction degree has been proposed. An equation for estimation of changes in this parameter during the reaction, on the basis of the initial value, has been presented. In the range of our data and the analysis of the literature data, the model, with satisfactory accuracy, describes internal structural changes of coal and coal char particles. The present results may constitute a basis for complex modelling of coal conversion processes. Based on the results it was found that the total active centres are related to the internal surface area and porosity of the particle. For a specific coal type, this value depends on the porosity, true density and size of the particle. Changes in total active centres, when these structural properties during thermal conversion of coal are considered, are described in equations.
The prevalence of vitamin D deficiency in the American and European population is estimated to be extremely high. Although fewer people today suff er from serious health problems related to calcium and phosphate metabolism resulting from vitamin D deficiency, there are more and more studies suggesting that calcitriol may play an important role in the pathogenesis of other diseases in virtually every body system. A growing body of research shows that through its ubiquitously expressed receptor, calcitriol displays potent anti-angiogenic an anti-inflammatory activity. Th is review summarizes recent discoveries regarding these non-classical eff ects of vitamin D and their clinical implications. Data collection focused on the prevention and treatment of ocular diseases as well as on the underlying mechanisms.
An economical alternative for the steel industry which uses a separate ferrosilicon and aluminum for the deoxidization of steel is a complex deoxidizer in the form of FeSiAl alloys. The effectiveness of complex deoxidizers is higher and they have a positive effect on quality improvement and also for mechanical properties of the finished steel. It is associated with a smaller number of non-metallic inclusions and a more favorable its distribution in the structure of steel. Noteworthy are the waste from the mining industry simultaneously contains SiO2 and Al2O3 oxides with a few of dopants in the form of CaO, MgO, FeO, TiO2 oxides. These wastes are present in large quantities and can be a cheap raw material for obtaining complex FeSiAl ferroalloys by an electrothermal method. “Poor” hard coal grades which so far did not apply as a reducing agent in the ferroalloy industry because of the high ash content can also be a raw material for the electrothermal FeSiAl process. The electrothermal FeSiAl melting process is similar to the ferrosilicon process in the submerged arc furnace. For this reason, a model based on Gibbs’ free enthalpy minimization algorithm was used to analyze the simultaneous reduction of SiO2 and Al2O3 oxides, which was originally elaborated for the ferrosilicon smelting process. This is a system of two closed reactors: the upper one with the lower temperature and the lower one with the higher temperature. Between the reaction system and the environment, and between the reactors inside the system, there is a cyclical mass transfer in moments when the state of equilibrium is reached in the reactors. Based on the model, the basic parameters of the electrothermal reduction process of SiO2 and Al2O3 oxides were determined and a comparative analysis was made towards the ferrosilicon process.
Higher active power of a submerged arc furnace is commonly believed to increase its capacity in the process of ferrosilicon smelting. This is a true statement but only to a limited extent. For a given electrode diameter d, there is a certain limit value of the submerged arc furnace active power. When this value is exceeded, the furnace capacity in the process of ferrosilicon smelting does not increase but the energy loss is higher and the technical and economic indicators become worse. Maximum output regarding the reaction zone volumes is one of parameters that characterize similarities of furnaces with various geometrical parameters. It is proportional to d3 and does not depend on the furnace size. The results of statistical analysis of the ferrosilicon smelting process in the 20 MVA furnace have been presented. In addition to basic electrical parameters, such as active power and electrical load of the electrodes, factors contributing to higher resistance of the furnace bath and resulting lower reactive power Px demonstrate the most significant effect on the electrothermal process of ferrosilicon smelting. These parameters reflect metallurgical conditions of ferrosilicon smelting, such as the reducer fraction, position of the electrodes and temperature conditions of the reaction zones.
O b j e c t i v e: The main goal of our studies was to investigate the eff ect exerted by pulsed electromagnetic filed (PEMF) on adipocytokines secretion in cell culture supernatants from rat adipose derived stem cells (ADSCs) grown on varied energy-rich diet. Off spring and adult animals were randomly selected for two types of experimental diets: low (LF) or high fat (HF) diet for 7 weeks. After the diet period, serum glucose level was measured, ADSCs were isolated from adipose tissues from different locations. ADSCs from all experimental groups were exposed to PEMF, supernatants collected and adipokines level was determined. R e s u l t s: HF diet feed in pups/adult animals elevated blood glucose level and increased the level of adiponectin (Apn) and leptin of both genders and age measured in serum. ADSCs cell cultures originated from female pups on LF diet and exposed to PEMF released large amounts of Apn. PEMF effect exerted on Apn release was also observed in ADSCs isolated from male pups HF diet. ADSCs from female pups on LF diet exposed to PEMF released smaller amounts of leptin in comparison to cell cultures without PEMF treatment. PEMF exposure of ADSCs cell cultures originated from female adults on LF diet decreased release of Apn, contrary adult male on LF diet ADSCs under PEMF treatment produced more leptin. PEMF treated male HF diet-originated ADSCs cultures released significantly more leptin than controls. C o n c l u s i o n: Our results suggest that PEMF exposure is responsible for metabolic physiological balance effects obtained in ADSCs cultures originating from adult animals on HF diet.
Objective: The aim of this study was to verify if the exposure to the pulsed electromagnetic field (PEMF) infl uenced the release of proinfl ammatory cytokines from adipose-derived stem cells (ADSCs) of normal and overweight rats of various age and sex. Moreover, we compared body temperatures of normal-weight and overweight rats. Methods: ADSCs of Wistar rats were isolated from the subcutaneous area in females and paratesticular region in males, cultured and exposed to PEMF (7 Hz, 30 mT). Concentrations of proinflammatory cytokines were determined in rat sera and supernatant from ADSCs cultures exposed and non-exposed to PEMF. Body temperature (BT) was measured twice a week, using an infrared and rectal thermometer. Results: Irrespective of age and sex, animals maintained on low-fat (LF) diet had higher BT than those grown on high-fat (HF) diet. Exposure to PEMF reduced the release of TNF-α and enhanced the production of IL-6 in ADSCs cultures from female pups maintained on LF diet. In contrast, a decrease in IL-6 level was observed in PEMF-exposed ADSCs cultures from female pups grown on HF diet. A similar phenomenon, i.e. a post-exposure increase in IL-6 level was also observed in male pups fed with the LF diet. In the case of ADSCs cultures from adult rats maintained on an HF diet, either males or females, PEMF exposure contributed to a dramatic increase in TNF-α production. Conclusion: Our findings suggest that PEMF exposure may affect the production of proinflammatory cytokines in ADSCs cultures. The intergroup diff erences in BT may result from the presence of an underlying inflammation in obese rats.
Extremely intense development of civilization requires from foundry casting technologies very high quality and not expensive castings. In the foundries, there are many treatments that allow increasing of the final properties of produced castings such as refining, modification, heat treatment, etc. One of the methods of increasing the quality of the casting by removing inclusions from the liquid alloy is filtration. The use of ceramic-carbon foam filters in filtration process is still analysed phenomenon that allows improving the final properties of castings. A modern method of research, testing and synthesis of innovative chemical compositions allows improving the properties of such filters. In the paper the evaluation of application properties of developed ceramic-carbon bonded foam filters is presented. The quality of the foam filters is evaluated by Computer Tomography and foundry trials in pouring of liquid metal in test molds. Additionally computer simulations were made to visualize the flow characteristics in the foam filter. The analysed filters are the result of the research work of Foundry Research Institute and the Institute of Ceramics and Building Materials, Refractory Materials Department in Gliwice.