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排序方式: 共有763条查询结果,搜索用时 15 毫秒
31.
Maxim A. Pozdniakov Konstantin V. Rubtsov Vladimir V. Botvin Alexander A. Sorvanov Alexey S. Knyazev 《分离科学与技术》2017,52(5):876-882
Separation of glyoxylic acid from unpurified multicomponent technological mixtures, resulting in the process of direct oxidation of glyoxal, and preparation of sodium glyoxylate are developed. The mixtures are treated with an optimal amount of CaCO3, which has to be prespecified by acidic–basic titration of the technological mixtures. Both separation of glyoxylic acid and preparation of sodium glyoxylate take place owing to ionic exchange reactions: calcium glyoxylate is easily converted into glyoxylic acid by action of oxalic acid. Reaction with Na2CO3 leads to the formation of sodium glyoxylate. 相似文献
32.
A. V. Terekhov L. N. Zanaveskin K. L. Zanaveskin O. A. Konorev 《Catalysis in Industry》2013,5(1):32-41
Carbon tetrachloride, classified as an ozone-depleting substance in the Montreal Protocol, is formed as a byproduct in the production of chlorinated hydrocarbons (chloromethanes, perchloroethylene, etc.). To develop a rational method of CCl4 utilization (an alternative to burning), in this work we study the liquid-phase catalytic hydrodechlorination of CCl4 with the formation of useful products such as sodium formiate, hexachloroethane, and perchloroethylene in the presence of aqueous sodium hydroxide solutions. Experiments are performed in a 300-mL autoclave at pressures of up to 1.5 MPa within a temperature range of 80–120°C on a Pd catalyst on sibunite (5 fractions, 0.1 to 1.6 mm). The dependences of the CCl4 conversion and the selectivities with respect to the principal reaction products on the initial concentrations of CCl4 and NaOH, the temperature, the partial pressure of hydrogen, the size of catalyst particles, and the palladium content in a catalyst are studied. Using the obtained data as a basis, we propose a process flowsheet, make some recommendations on the process conditions (depending on the specified composition of products), and determine the optimum catalyst characteristics: 1.5 wt % Pd on sibunite with a grain size of 0.315–0.63 mm. The proposed process allows us not only to solve the problem of recycling CCl4-containing wastes, but also to provide the production of three marketable products. 相似文献
33.
Mikhail V. Samsonov Nikita V. Podkuychenko Asker Y. Khapchaev Eugene E. Efremov Elena V. Yanushevskaya Tatiana N. Vlasik Vadim Z. Lankin Iurii S. Stafeev Maxim V. Skulachev Marina V. Shestakova Alexander V. Vorotnikov Vladimir P. Shirinsky 《International journal of molecular sciences》2022,23(1)
Hyperlipidemia manifested by high blood levels of free fatty acids (FFA) and lipoprotein triglycerides is critical for the progression of type 2 diabetes (T2D) and its cardiovascular complications via vascular endothelial dysfunction. However, attempts to assess high FFA effects in endothelial culture often result in early cell apoptosis that poorly recapitulates a much slower pace of vascular deterioration in vivo and does not provide for the longer-term studies of endothelial lipotoxicity in vitro. Here, we report that palmitate (PA), a typical FFA, does not impair, by itself, endothelial barrier and insulin signaling in human umbilical vein endothelial cells (HUVEC), but increases NO release, reactive oxygen species (ROS) generation, and protein labeling by malondialdehyde (MDA) hallmarking oxidative stress and increased lipid peroxidation. This PA-induced stress eventually resulted in the loss of cell viability coincident with loss of insulin signaling. Supplementation with 5-aminoimidazole-4-carboxamide-riboside (AICAR) increased endothelial AMP-activated protein kinase (AMPK) activity, supported insulin signaling, and prevented the PA-induced increases in NO, ROS, and MDA, thus allowing to maintain HUVEC viability and barrier, and providing the means to study the long-term effects of high FFA levels in endothelial cultures. An upgraded cell-based model reproduces FFA-induced insulin resistance by demonstrating decreased NO production by vascular endothelium. 相似文献
34.
大塑性变形纳米结构Al-Mg合金中的形变缺陷和电子辐照效应 总被引:1,自引:0,他引:1
为澄清大塑性变形纳米结构Al-Mg合金中形变缺陷形成的本质,采用高分辨透射电子显微镜(HRTEM)研究电子辐照对高压扭转合金中面缺陷形成的影响。结果表明:对已有高密度面缺陷的HRTEM图像,经电子束照射一段时间后,这些面缺陷会完全消失;而在没有缺陷的HRTEM图像区域进行电子辐照,即使电子束的照射提高到足以在该区域击出孔洞,整个过程均未观察到任何晶格缺陷。因此,高压扭转合金中的面缺陷主要来源于极度的塑性变形,而与HRTEM观察过程中的电子辐照效应无关。 相似文献
35.
Sankalp Kota Louisiane Verger Varun Natu Maxim Sokol Michel W. Barsoum 《Journal of the American Ceramic Society》2021,104(2):733-739
The thermal stability and decomposition mechanisms of Fe2AlB2 powders, synthesized by reactive powder metallurgy, were studied under nitrogen (N2) or argon (Ar) atmospheres. The effects of using different FeB precursors to synthesize the Fe2AlB2 and hydrochloric acid (HCl) purification treatments on the thermal stability were also investigated. When as-synthesized Fe2AlB2 powders are treated in dilute HCl to dissolve impurity phases, decomposition in N2 atmospheres occurs readily above 1200 K. The decomposition reaction involves β-FeB precipitation and the liberated Al atoms reacting with the ambient N2 to form AlN. Under Ar environments, HCl-treated Fe2AlB2 powders decompose and precipitate β-FeB, by the out-diffusion of Al from the nanolaminated structure. Interestingly, isothermal annealing under N2 atmospheres revealed that Fe2AlB2 was more thermally stable when synthesized from lab-synthesized, instead of commercially available, FeB precursors and when the HCl treatment was avoided. The effects of the various factors on the decomposition temperature and decomposition mechanisms are discussed herein. 相似文献
36.
A. I. Andrianov A. G. Afonin I. A. Gusev O. V. Zyatkov N. A. Ignashin A. V. Larionov E. A. Ludmirsky A. V. Maximov A. A. Matyushin A. V. Minchenko M. S. Mikheev V. N. Peleshko V. D. Rudko V. I. Terekhov N. E. Tyurin Y. S. Fedotov 《Instruments and Experimental Techniques》2016,59(3):385-392
The first results of Proton Radiographic Facility operation on the beam with energies of 50–70 GeV extracted from the U-70 synchrotron at the Institute for High Energy Physics are presented. This facility is capable of forming proton radiographic images of samples with an optical thickness as large as 450 g/cm2 and a field of view of 220 mm or more. 相似文献
37.
Rishi Pillai Samuel Pearson Maxim N. Gussev Thomas R. Watkins Bruce A. Pint 《工业材料与腐蚀》2021,72(8):1315-1327
Oxide scale exfoliation is a major concern in fossil fuel power generation because it can cause tube blockages and erode valves and steam turbine components downstream. There is still considerable scientific and commercial interest to improve the mechanistic understanding of oxide failures by developing models to predict exfoliation and the extent of tube blockage as a function of operating conditions and component geometries. Tensile testing inside a scanning electron microscope was conducted on ferritic–martensitic and austenitic steel specimens with the steam side (Fe,Cr)-rich oxides grown after exposures for up to 1000 h in steam with ~100 ppb O2 at 276 bar and 550°C. Multiple oxide layer cracks and delamination events were observed and analyzed in detail during the tests. Results from the testing agreed well with earlier observations that had identified the failure location at the outer–inner oxide layer for all tested materials. Calculated adhesion energies identified the outer–inner oxide interface of alloy 347HFG as the weakest interface. 相似文献
38.
Alsu Z. Malikova Anastasia S. Shcherbakova Konstantin A. Konduktorov Anastasia S. Zemskaya Alexandra A. Dalina Vladimir I. Popenko Olga G. Leonova Alexei V. Morozov Nikolay N. Kurochkin Olga A. Smirnova Sergey N. Kochetkov Maxim V. Kozlov 《International journal of molecular sciences》2021,22(9)
Recent evidence suggests that fibrotic liver injury in patients with chronic hepatitis C correlates with cellular senescence in damaged liver tissue. However, it is still unclear how senescence can affect replication of the hepatitis C virus (HCV). In this work, we report that an inhibitor of cyclin-dependent kinases 4/6, palbociclib, not only induced in hepatoma cells a pre-senescent cellular phenotype, including G1 arrest in the cell cycle, but also accelerated viral replicon multiplication. Importantly, suppression of HCV replication by direct acting antivirals (DAAs) was barely affected by pre-senescence induction, and vice versa, the antiviral activities of host-targeting agents (HTAs), such as inhibitors of human histone deacetylases (HDACi), produced a wide range of reactions—from a dramatic reduction to a noticeable increase. It is very likely that under conditions of the G1 arrest in the cell cycle, HDACi exhibit their actual antiviral potency, since their inherent anticancer activity that complicates the interpretation of test results is minimized. 相似文献
39.
Nadezhda A. Evtushenko Arkadii K. Beilin Erdem B. Dashinimaev Rustam H. Ziganshin Anastasiya V. Kosykh Maxim M. Perfilov Alexandra L. Rippa Elena V. Alpeeva Andrey V. Vasiliev Ekaterina A. Vorotelyak Nadya G. Gurskaya 《International journal of molecular sciences》2021,22(8)
The recessive form of dystrophic epidermolysis bullosa (RDEB) is a crippling disease caused by impairments in the junctions of the dermis and the basement membrane of the epidermis. Using ectopic expression of hTERT/hTERT + BMI-1 in primary cells, we developed expansible cultures of RDEB fibroblasts and keratinocytes. We showed that they display the properties of their founders, including morphology, contraction ability and expression of the respective specific markers including reduced secretion of type VII collagen (C7). The immortalized keratinocytes retained normal stratification in 3D skin equivalents. The comparison of secreted protein patterns from immortalized RDEB and healthy keratinocytes revealed the differences in the contents of the extracellular matrix that were earlier observed specifically for RDEB. We demonstrated the possibility to reverse the genotype of immortalized cells to the state closer to the progenitors by the Cre-dependent hTERT switch off. Increased β-galactosidase activity and reduced proliferation of fibroblasts were shown after splitting out of transgenes. We anticipate our cell lines to be tractable models for studying RDEB from the level of single-cell changes to the evaluation of 3D skin equivalents. Our approach permits the creation of standardized and expandable models of RDEB that can be compared with the models based on primary cell cultures. 相似文献
40.
Maxim Finkelstein 《Reliability Engineering & System Safety》2009,94(8):1358-1362
Simple series systems of identical components with spare parts are considered. It is shown that the cumulative distribution function of a system failure time tends to be a step function as the number of components increases and resources can be shared. An example of ‘continuous resources’ is also described. The time-sharing strategy for standby systems is investigated. It is proved that an optimal rule for a system of standby components with increasing failure rates is the single switching performed at a=t/2, where t is the mission time. 相似文献