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31.
Grigory Kovtun Tatiana Kameneva Serhy Hladyi Mykhailo Starchevsky Yury Pazdersky Igor Stolarov Michael Vargaftik Ilya Moiseev 《Advanced Synthesis \u0026amp; Catalysis》2002,344(9):957-964
Redox disproportionation of benzyl alcohol to benzaldehyde and toluene catalysed by the Pd561phen60(OAc)180 (phen=1,10‐phenanthroline) giant cluster 1 under anaerobic conditions was found, whereas in an O2 atmosphere cluster 1 catalyses the oxidation of benzyl alcohol to benzaldehyde and inhibits further oxidation of the latter. A study of the AIBN‐initiated and non‐initiated oxidation of benzyl alcohol, sec‐butyl alcohol and styrene in the presence of cluster 1 revealed that cluster 1 performs three functions in the oxidation reactions: 1) catalysis of polar oxidation of the substrates with O2, 2) termination of the chains of radical oxidation, and 3) catalysis of redox disproportionation. 相似文献
32.
Tatiana V. Rozhko Elena V. Nemtseva Maria V. Gardt Alexander V. Raikov Albert E. Lisitsa Gennadii A. Badun Nadezhda S. Kudryasheva 《International journal of molecular sciences》2020,21(22)
The present study considers a possible role of enzymatic reactions in the adaptive response of cells to the beta-emitting radionuclide tritium under conditions of low-dose exposures. Effects of tritiated water (HTO) on the reactions of bacterial luciferase and NAD(P)H:FMN-oxidoreductase, as well as a coupled system of these two reactions, were studied at radioactivity concentrations ≤ 200 MBq/L. Additionally, one of the simplest enzymatic reactions, photobiochemical proton transfer in Coelenteramide-containing Fluorescent Protein (CLM-FP), was also investigated. We found that HTO increased the activity of NAD(P)H:FMN-oxidoreductase at the initial stage of its reaction (by up to 230%); however, a rise of luciferase activity was moderate (<20%). The CLM-FP samples did not show any increase in the rate of the photobiochemical proton transfer under the exposure to HTO. The responses of the enzyme systems were compared to the ‘hormetic’ response of luminous marine bacterial cells studied earlier. We conclude that (1) the oxidoreductase reaction contributes significantly to the activation of the coupled enzyme system and bacterial cells by tritium, and (2) an increase in the organization level of biological systems promotes the hormesis phenomenon. 相似文献
33.
Kazuo Tsubota Stephen C. Pflugfelder Zuguo Liu Christophe Baudouin Hyo Myung Kim Elisabeth M. Messmer Friedrich Kruse Lingyi Liang Jimena Tatiana Carreno-Galeano Maurizio Rolando Norihiko Yokoi Shigeru Kinoshita Reza Dana 《International journal of molecular sciences》2020,21(23)
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint. 相似文献
34.
Carla F. Fávaro Tatiana B. Santos Paulo H. G. Zarbin 《Journal of chemical ecology》2012,38(9):1124-1132
Agroecus griseus is a serious corn pest in Brazil. Contents of the dorsal abdominal glands (DAGs) in nymphs, and the metathoracic gland (MTG) in adults of this species were characterized and quantified. Compounds found were similar to those of other Pentatomidae species and included aliphatic hydrocarbons, aldehydes, oxo-alkenals, and esters. However, two compounds were found in the MTG that have not been described previously for this family. Mass spectrometry, infrared spectroscopy, and gas chromatographic analysis using coinjection with authentic standards confirmed the identities of the compounds as enantiopure (S)-2-methylbutyl acetate and 3-methyl-2-butenyl acetate. The five nymphal instars showed significantly different ratios of components, mainly between those of the first and later instars. No significant differences were detected in MTG contents between sexes. Gas chromatography (GC) analysis of aeration extracts of males and females showed the presence of a compound released exclusively by males. Gas chromatography – electroantennographic detection (GC-EAD) assays indicated that the male-specific compound is bioactive in females, suggesting the presence of an attractant pheromone. The mass spectrum and infrared data for this compound matched with methyl 2,6,10-trimethyltridecanoate, a sex pheromone component previously detected in the stink bugs, Euschistus heros and E. obscurus. The synthetic standard coeluted with the natural pheromone on two different GC stationary phases, confirming the proposed structure. Y-tube olfactometer assays showed that the synthetic standard was strongly attractive to females, and GC-EAD tests produced responses with antennae from females similar to those of the natural pheromone. 相似文献
35.
Oliver Y. Gutirrez Fernando Prez Gustavo A. Fuentes Xim Bokhimi Tatiana Klimova 《Catalysis Today》2008,130(2-4):292-301
In the present work, with the aim of searching for new, highly effective catalysts for deep HDS, a series of NiMo catalysts with different MoO3 loadings (6–30 wt.%) was prepared using SBA-15 material covered with ZrO2-monolayer as a support. Prepared catalysts were characterized by N2 physisorption, small- and wide-angle XRD, UV–vis diffuse reflectance spectroscopy, temperature-programmed reduction, SEM-EDX and HRTEM, and their catalytic activity was evaluated in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). It was observed that ZrO2 incorporation on the SBA-15 surface improves the dispersion of the Ni-promoted oxidic and sulfided Mo species, which were found to be highly dispersed, up to 18 wt.% of MoO3 loading. Further increase in metal charge resulted in the formation of MoO3 crystalline phase and an increase in the stacking degree of the MoS2 particles. All NiMo catalysts supported on ZrO2-modified SBA-15 material showed high activity in HDS of 4,6-DMDBT. The best catalyst having 18 wt.% MoO3 and 4.5 wt.% NiO was almost twice more active than the reference NiMo/γ-Al2O3 catalyst. High activity of NiMo/Zr-SBA-15 catalysts and its evolution with metal loading was related to the morphological characteristics of the MoS2 active phase determined by HRTEM. 相似文献
36.
Kinetics and mechanism of low-temperature ozone decomposition by Co-ions adsorbed on silica 总被引:3,自引:0,他引:3
Tatiana L. Rakitskaya Alim A. Ennan Irina V. Granatyuk Alexander Yu. Bandurko Gilbert G. A. Balavoine Yurii V. Geletii V. Ya. Paina 《Catalysis Today》1999,53(4):616-723
Kinetics and mechanism of low-temperature ozone ((5–50) × 10−3 mol/m3 in the gas–air mixture) decomposition by Co-catalysts supported on silica have been studied. Co-ions adsorbed on silica react with surface oxygen species, thus resulting in an active catalyst. Low concentrations of Co-ions form a monolayer on the surface. Their specific catalytic activity remained constant, but sharply decreased at higher concentrations due to a formation of polynuclear Co-complexes. Ozone decomposition may occur either as a stoichiometric or catalytic process, depending on the ozone and catalyst concentrations. The turnover number increases with ozone concentration reaching a saturation point. It also increases with Co-concentration in the beginning, but drops at a concentration >1 × 10−4 mol/g. The mechanism of the reaction is discussed. 相似文献
37.
刘庆备 《高科技纤维与应用》2009,34(3):31-36
通过调节高分子体系的结构,可以有目的性地设计含有固化药物成分(如生物酶和/或抗菌剂)的高分子基体结构,生物活性的高低主要由固化的药物成分决定。 相似文献
38.
Larisa I. Nasibulina Tatiana S. Koltsova Tuomo Joentakanen Albert G. Nasibulin Oleg V. Tolochko Jari E.M. Malm Maarit J. Karppinen Esko I. Kauppinen 《Carbon》2010,48(15):4559-4562
A novel approach to synthesize carbon nanofibers (CNFs) directly on the surface of metal μm-sized particles to evenly disperse the carbon nanomaterials in a composite material was proposed. As a metal matrix, 5–10 μm copper particles were utilized. As a carbon source, C2H2, CH4 and CO were examined. The best conditions were found to be in C2H2 (30 cm3/min) and H2 (260 cm3/min) atmosphere at the temperature of 750 °C. The composites based on copper and CNFs prepared by vacuum hot pressing showed the increase in hardness from 35 to 60 kg/mm2 almost retaining pure copper electrical properties. 相似文献
39.
40.
Margarita A. Sazonova Vasily V. Sinyov Anastasia I. Ryzhkova Marina D. Sazonova Tatiana V. Kirichenko Victoria A. Khotina Zukhra B. Khasanova Natalya A. Doroschuk Vasily P. Karagodin Alexander N. Orekhov Igor A. Sobenin 《International journal of molecular sciences》2021,22(2)
Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism’s nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress. 相似文献