20 research outputs found
Гідродинаміка руху теплового агента під час фільтраційного сушіння Miscánthus giganteus
Experimental studies of pressure losses in a layer of crushed miscánthus giganteus for changes in the fake rate of filtration of the thermal agent and also hydrodynamics of the layer miscanthus giganteus from the fictitious rate of the thermal agent, which are parabolic in nature for all the heights of the material layer, are presented. The hydrodynamics of the flow of gas through a stationary porous layer of material using Darcy – Weissbach dependence is described. The porosity of the material layer is determined. The equation describing the complex dependence between the pressure and the speed caused by the elastic properties of miscánthus giganteus is obtained. The results of these functions are derived for different values of height, porosity and false speed. An equation describing the complex dependence between the pressure and the speed caused by the elastic properties of miscánthus giganteus is obtained. Comparative theoretical and experimental data are presented. The obtained equation allows predicting the energy costs of creating a pressure drop during drying in the stationary layer miscánthus giganteus within the limits of the height of the layer and fictitious velocity. The relationship between pressure flow, speed, porosity, and altitude is experimentally defined. The coefficient of resistance of the miscánthus giantheus layer is determined and presented in the form of dimensionless complexes as a function of the Reynolds number. Experimental data for determining the resistance coefficient is provided. Experimental results are presented that allow predicting energy costs for the drying process. The hydraulic friction coefficient is determined which enables to predict the energy costs of the filtration drying process in the wide limits of the filtration rate of the thermal agent. The absolute value of the relative error between the theoretical calculation and experimental data is analyzed. We recommend dependencies that can be used in practice to predict the energy costs of creating a pressure drop during the calculation and design of miscánthus giganteus filtration drying installations.Наведено результати експериментальних досліджень гідродинаміки руху теплового агента крізь стаціонарний шар подрібненого Miscánthus giganteus. Визначено основні параметри шару miscánthus giganteus та вибрано еквівалентний діаметр каналів між частинками de. Подано основні технічні характеристики miscánthus giganteus. Проведено експериментальні дослідження гідродинаміки фільтрування теплового агента крізь стаціонарний шар miscánthus giganteus. Наведено експериментальні дослідження гідродинаміки шару miscánthus giganteus від фіктивної швидкості теплового агента. Отримано рівняння, яке описує складну залежність між напором і швидкістю, зумовлену пружними властивостями miscánthus giganteus. Отримане рівняння дає змогу прогнозувати енергетичні затрати на створення перепаду тиску під час сушіння в стаціонарному шарі Miscánthus giganteus у межах зазначених похибки і меж висоти шару та фіктивної швидкості. Представлено коефіцієнт опору шару miscánthus giganteus у вигляді безрозмірних комплексів як функцію числа Рейнольдса. Визначено коефіцієнт гідравлічного тертя l. Проаналізовано абсолютне значення відносної похибки між теоретично розрахованими значеннями та експериментальними даними. Одержано критеріальні залежності, які дають змогу використати отримані результати для проектування нового сушильного обладнання за подібних гідродинамічних умов
СОПРЯЖЕННЫЙ ТЕПЛООБМЕН ПРИ ПОЛУЧЕНИИ СТЕКЛЯННЫХ МИКРОСФЕР В ГАЗОПЛАМЕННОМ РЕАКТОРЕ
A model for the process of glass microsphere production in a recuperative gas-flame reactor was proposed. Based on the described mathematical model of heating and motion of particles in a high-temperature gas stream, which takes into account conjugate heat exchange between the reactor’s operating environment and the recuperator, the appropriate processes were modeled and optimized by geometric and regime parameters. The particle location time in the reactor at a temperature above 1400 °С, which was determined by data of differential scanning colorimetry, was used as an optimized charac- С, which was determined by data of differential scanning colorimetry, was used as an optimized charac- , which was determined by data of differential scanning colorimetry, was used as an optimized characteristic.As a result of optimization calculations, the reactor parameters (diameter and height, natural gas flow rate, air flow rate in the recuperator) were found, as well as regime parameters (diameter and flow rate of glass particles), under which microspheres can be formed. The information obtained can be a basis for designing an effective gas-flame reactor for production of glass microspheres.В работе была предложена модель, описывающая процесс получения стеклянных микросфер в газопламенном реакторе рекуперативного типа. На основе описанной математической модели нагрева и движения частиц в высокотемпературном газовом потоке, учитывающей сопряженный теплообмен между рабочей средой реактора и рекуператором, проведено моделирование и оптимизация соответствующих процессов по геометрическим и режимным параметрам. В качестве оптимизируемой характеристики использовалось время пребывания частиц стекла в реакторе при температуре выше 1400 °С, которое определено на основе данных дифференциальной сканирующей колориметрии.В результате оптимизационных расчетов найдена область параметров реактора (диаметр и высота, расход при-родного газа, расход продуваемого через рекуператор воздуха), а также режимных параметров (диаметр и расход частиц стекла), в которых возможно формирование микросфер. Полученная информация может служить основой для проектирования эффективного газопламенного реактора для получения стеклянных микросфер
Application of Antimicrobial Peptides of the Innate Immune System in Combination With Conventional Antibiotics—A Novel Way to Combat Antibiotic Resistance?
Rapidly growing resistance of pathogenic bacteria to conventional antibiotics leads to inefficiency of traditional approaches of countering infections and determines the urgent need for a search of fundamentally new anti-infective drugs. Antimicrobial peptides (AMPs) of the innate immune system are promising candidates for a role of such novel antibiotics. However, some cytotoxicity of AMPs toward host cells limits their active implementation in medicine and forces attempts to design numerous structural analogs of the peptides with optimized properties. An alternative route for the successful AMPs introduction may be their usage in combination with conventional antibiotics. Synergistic antibacterial effects have been reported for a number of such combinations, however, the molecular mechanisms of the synergy remain poorly understood and little is known whether AMPs cytotoxicy for the host cells increases upon their application with antibiotics. Our study is directed to examination of a combined action of natural AMPs with different structure and mode of action (porcine protegrin 1, caprine bactenecin ChBac3.4, human alpha- and beta-defensins (HNP-1, HNP-4, hBD-2, hBD-3), human cathelicidin LL-37), and egg white lysozyme with varied antibiotic agents (gentamicin, ofloxacin, oxacillin, rifampicin, polymyxin B, silver nanoparticles) toward selected bacteria, including drug-sensitive and drug-resistant strains, as well as toward some mammalian cells (human erythrocytes, PBMC, neutrophils, murine peritoneal macrophages and Ehrlich ascites carcinoma cells). Using “checkerboard titrations” for fractional inhibitory concentration indexes evaluation, it was found that synergy in antibacterial action mainly occurs between highly membrane-active AMPs (e.g., protegrin 1, hBD-3) and antibiotics with intracellular targets (e.g., gentamicin, rifampcin), suggesting bioavailability increase as the main model of such interaction. In some combinations modulation of dynamics of AMP-bacterial membrane interaction in presence of the antibiotic was also shown. Cytotoxic effects of the same combinations toward normal eukaryotic cells were rarely synergistic. The obtained data approve that combined application of antimicrobial peptides with antibiotics or other antimicrobials is a promising strategy for further development of new approach for combating antibiotic-resistant bacteria by usage of AMP-based therapeutics. Revealing the conventional antibiotics that increase the activity of human endogenous AMPs against particular pathogens is also important for cure strategies elaboration
Correlation effects during liquid infiltration into hydrophobic nanoporous mediums
Correlation effects arising during liquid infiltration into hydrophobic
porous medium are considered. On the basis of these effects a mechanism of
energy absorption at filling porous medium by nonwetting liquid is suggested.
In accordance with this mechanism, the absorption of mechanical energy is a
result expenditure of energy for the formation of menisci in the pores on the
shell of the infinite cluster and expenditure of energy for the formation of
liquid-porous medium interface in the pores belonging to the infinite cluster
of filled pores. It was found that in dependences on the porosity and,
consequently, in dependences on the number of filled pores neighbors, the
thermal effect of filling can be either positive or negative and the cycle of
infiltration-defiltration can be closed with full outflow of liquid. It can
occur under certain relation between percolation properties of porous medium
and the energy characteristics of the liquid-porous medium interface and the
liquid-gas interface. It is shown that a consecutive account of these
correlation effects and percolation properties of the pores space during
infiltration allow to describe all experimental data under discussion
Высокотеплопроводная карбидокремниевая керамика для крупногабаритной космической оптики
The paper describes the important aspects of the developed technology for manufacturing silicon-carbide substrates for optical mirrors intended for future use in space applications. It is shown that the material with the best combination of thermophysical and mechanical properties (Maksutov’s criterion) among the known analogs used for making astronomical mirrors is obtained. The characteristics of a mirror made of a lightweight mirror substrate with a diameter of 205 mm are described, compared with the parameters of most known mirrors made of silicon carbide for various space missions and as proto types. It is shown that the produced substrate is characterized by a rather low specific gravity – 16.5 kg/m2, which is comparable with the indicators of the best world analogues.Описаны важные аспекты разработанной технологии изготовления карбидокремниевых подложек для оптических зеркал, предназначенных для перспективного использования в космических приложениях. Показано, что получен материал с лучшим сочетанием теплофизических и механических свойств (критерий Максутова) среди известных аналогов, применяемых при создании астрономических зеркал. Описаны характеристики изготовленной из него облегченной подложки зеркала диаметром 205 мм, проведено сравнение с параметрами большинства известных зеркал, изготовленных из карбида кремния для различных космических миссий и в качестве опытных образцов. Показано, что изготовленная подложка характеризуется низкой удельной массой – 16,5 кг/м2, что сопоставимо с показателями лучших мировых аналогов
On the Nature of Concentration Limits of Combustion Wave Propagation in Powdered and Pelletized Ti + C + xAl2O3 Mixtures
Diagnosis with spectral infrared thermography in the treatment of gunshot wound of soft tissue
Можливість швидкої та об’єктивної оцінки глибини і тяжкості ураження інфекцією м’яких тканин
при вогнепальних пораненнях завжди була значною діагностичною проблемою бойової вогнепальної
травми.
Використання спектральної інфрачервоної термографії зони ушкодження при вогнепальних пораненнях м’яких тканин є перспективним методом первинної діагностики для встановлення фази, інтенсивності та розповсюдженості ранового процесу.A possibility of rapid and objective estimation of depth and severity of infectional damage to the soft tissues
with shotgun wounds always was a considerable diagnostic problem of battle shotgun trauma.
The use of spectral infra-red thermography of the damage area with shotgun wounds of the soft tissues is a
perspective method of primary diagnostics for determination of the phase, intensity and the wound process
prevalence