Time-resolved Visualization of Laser Beam Melting of Silica Glass Powder

AbstractSilica glass is an inorganic dielectric material that can be used for laser beam melting without cracking. However, the extremely high viscosity makes consolidation of powder very slow. To study the dynamics of consolidation, a 10.6μm laser beam was directed on the powder layer deposited on the solid substrate of the same material. The laser-interaction zone was lighted with green laser and filmed with a high-speed camera at 6000 fps. The process develops steadily. Neither fluctuation nor droplets are observed. An expanding consolidation zone is observed. Viscous merging of softened powder particles is supposed to be the principal mechanism of consolidation. Mathematical model based on this mechanism confirms formation of the consolidated zone in the center. Both the experiment and the model indicate that consolidation looks like propagation of a sharp front. Comparison of the experiments and the calculations estimates the consolidation front temperature of about 1800-1900K

Artesunate potentiates antibiotics by inactivating heme-harbouring bacterial nitric oxide synthase and catalase

<p>Abstract</p> <p>Background</p> <p>A current challenge of coping with bacterial infection is that bacterial pathogens are becoming less susceptible to or more tolerant of commonly used antibiotics. It is urgent to work out a practical solution to combat the multidrug resistant bacterial pathogens.</p> <p>Findings</p> <p>Oxidative stress-acclimatized bacteria thrive in rifampicin by generating antibiotic-detoxifying nitric oxide (NO), which can be repressed by artesunate or an inhibitor of nitric oxide synthase (NOS). Suppressed bacterial proliferation correlates with mitigated NO production upon the combined treatment of bacteria by artesunate with antibiotics. Detection of the heme-artesunate conjugate and accordingly declined activities of heme-harbouring bacterial NOS and catalase indicates that artesunate renders bacteria susceptible to antibiotics by alkylating the prosthetic heme group of hemo-enzymes.</p> <p>Conclusions</p> <p>By compromising NO-mediated protection from antibiotics and triggering harmful hydrogen peroxide burst, artesunate may serve as a promising antibiotic synergist for killing the multidrug resistant pathogenic bacteria.</p

Utilization of the wastes of vital activity

The recycling of wastes from the biological complex for use in life-support systems is discussed. Topics include laboratory equipment, heat treatment of waste materials, mineralization of waste products, methods for production of ammonium hydroxide and nitric acid, the extraction of sodium chloride from mineralized products, and the recovery of nutrient substances for plants from urine

Choice of Anesthesia for Orthopedic Surgery in Elderly and Senile Patients (Review)

Management of elderly and senile patients is a major challenge due to significant comorbidity, especially in surgery under general anesthesia.The aim of the review was to identify the optimal method of anesthesia for knee arthroplasty in elderly patients based on the available clinical and experimental studies.We searched PubMed, Medline, and Elibrary.ru databases for relevant sources. Out of more than 300 publications initially analyzed, 113 literature sources (dating from 1951 to 2021) were included in the review, of which 80 were published within the last five years (2016–2021). The inclusion criteria were high informative value and relevance, except for sources cited as historical references. Both randomized multicenter studies and individual case reports were included in the review. Exclusion criteria were low informative value, outdated and repetitive data.We reviewed the physiology of elderly and senile patients, various variants of anesthesia, the use of neuroaxial anesthesia and peripheral regional blocks, xenon-based general anesthesia, assessed the advantages and drawbacks of each method, and discussed the monitoring of the depth of anesthesia and the issues of inraoperative awareness during knee arthroplasty in elderly and senile patients.Conclusion. The choice of anesthesia for knee arthroplasty in elderly and senile patients should be based on the risks of decompensation of cardiovascular comorbidities and cognitive impairment. No known anesthetic method is ideal in terms of safety. The use of xenon as the main anesthetic seems promising due to its cardio- and neuroprotective properties. However, its use is limited due to relatively high cost. Therefore, the search for optimal (lower than recommended) inhalation concentrations may lead to expanding use of xenon in elderly and senile patients. At the same time, the use of lower concentrations of the drug is associated with the intraoperative awakening and the need for its combination with narcotic analgesics or amnestic agents, which may not be optimal. In addition, the protective effect of xenon retrograde amnesia against the stress of unintended intraoperative awakening has not been studied, and routine methods of monitoring the depth of hypnosis when using xenon often yield skewed measurement results inconsistent with the clinical manifestations of anesthesia.Therefore, there is a need for further studies concerning the retrograde amnesic effect of xenon and search for optimal methods of assessing the depth of hypnosis when using this gas to safely reduce its inhalation concentration

Set-up for post-irradiation determination of temperature during nuclear reactor exposure with 3C-SiC

Research reactors currently rely on thermocouples for accurate temperature measurements in instrumented rigs. However, a lot of irradiations are carried out in lower cost instrumented capsules without instrumentation where thermocouples are not an option. In the latter case calculations or melt wires are used to determine the irradiation temperature. These methods do not suffice for state-of-the-art irradiations where temperature needs to be accurately known. Cubic Silicon Carbide (3C-SiC) is a potential material to use as post-irradiation (PI) temperature monitor which theoretically allows the determination of the irradiation temperature. Recent developments at Idaho National Laboratory and Oak Ridge National Laboratory show the possibility to use 3C-SiC as a routine PI temperature monitor in un-instrumented capsules by observing changes in electrical resistivity after isochronal annealing. This is a challenging task as it requires accurate electrical measurements on a high-resistivity semiconductor, performed on activated samples and at high temperatures (up to 1000°C

Фитосанитарные нормы и их влияние на международную торговлю растительной сельскохозяйственной продукцией (постановка проблемы)

Relevance and methods. he article examines the impact of phytosanitary standards on international trade in plant products. It is noted that it is complex in two ways: on the one hand, phytosanitary control protects against low-quality goods, non-native pests and diseases, on the other – negatively affects international trade, makes it difficult for small producers to enter the market, especially when it comes to developing countries. The study provides examples of Vietnam and Chile. Results. It is concluded that excessively strict phytosanitary regulations act more as a barrier than as a catalyst for trade. Moreover, there is a tendency to tighten requirements. The authors draw attention not only to the necessity, but also to the complexity of harmonization of phytosanitary standards.Актуальность. В статье рассматривается влияние фитосанитарных норм на международную торговлю растительной продукцией. Отмечается сложный двоякий характер фитосанитарного контроля: с одной стороны он защищает от некачественных товаров, неместных вредителей и болезней, с другой – негативно влияет на международную торговлю, затрудняет выход на рынок некрупных производителей, особенно когда речь идет о развивающихся странах. В исследовании приведены примеры Вьетнама, Чили. Результаты. Сделан вывод, что излишне строгая фитосанитарная регламентация действует в большей мере как барьер, нежели чем катализатор для торговли. Причем отмечена тенденция ужесточения требований. Авторы обращают внимание не только на необходимость, но и на сложность гармонизации фитосанитарных норм

Assessment of soil erosion rate trends in two agricultural regions of European Russia for the last 60 years

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Forest–steppe and the southern forest ecotones of European Russia (ER) are the most productive agricultural areas in Russia. Both climate and land use changes have occurred within the ER during last 30 years. These changes can lead to changes in the timing, magnitude, and spatial distribution of soil erosion rates on cultivated lands. The objective of this research was to assess the trends in soil erosion rates since the 1960s for two agricultural regions of ER. Materials and methods: Rates of soil erosion were estimated for two time windows (1963–1986 and 1986–2015) within the two agricultural regions. Both regions are characterized by a high proportion of cropland (> 60%), and within each region, one river basin and one 1st–3rd-order agricultural catchment were selected for a detailed assessment of soil erosion rates. Erosion models and visual interpretation of satellite images were used for the evaluation of the erosion rates for the river basins. Sediment budget assessments, 137Cs dating, geomorphologic mapping, and erosion models were used for the evaluation of the sediment redistribution for the two time windows in agricultural catchments. Results and discussion: At the river basin scale, the mean annual erosion rate did not change in the western part of forest–steppe ecotone; however, there was a weak negative trend in the mean annual erosion rate for the eastern part of the southern forest ecotone. A large negative trend in the erosion rate was found for both small agricultural catchments. In all cases, the reduction in the erosion rates was mainly associated with a decrease of surface runoff during snowmelt, as a result of an increase in both the air and soil temperatures during winter season. The soil loss reduction during snowmelt was counteracted by an equal increase in rainfall erosion due to increase of rainfall intensity in western part of forest–steppe ecotone. Conclusions: Reduction of surface runoff during spring snowmelt was the main reason the erosion rates declined on cultivated lands within the forest–steppe and southern forest ecotones of ER. Evaluation of ephemeral gully erosion rate was not incorporated into State Hydrological Institute erosion model used for the evaluation of the soil losses during snowmelt. This has led to an underestimation of the total soil losses for the 1963–1986 time window for all study sites