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排序方式: 共有1053条查询结果,搜索用时 15 毫秒
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Janine Will Lars Schneider Dr. Jonathan Becker Jun.-Prof. Dr. Sabine Becker Andreas Miska Christopher Gawlig Prof. Dr. Siegfried Schindler 《Israel journal of chemistry》2020,60(10-11):999-1003
A new tripodal imine ligand tris(2-(propan-2-ylideneamino)ethyl)amine (imine3tren) was prepared in order to stabilize high valent iron-oxido complexes. Iron complexes were synthesized in template reactions from iron(II) salts, tris(2-aminoethyl)amine (tren) and acetone. Due to the reversibility of the imine formation, complexes with different ligands were obtained depending on the reaction conditions. Three complexes, [Fe(imine3tren)(OAc)2] ( 1 ), [Fe(imine3tren)(OAc)]OTf ( 2 ) and [(imine3tren)2Fe2(F)2](SbF6)2 ( 3 ), could be synthesized and structurally characterized. However, reactions with hydrogen peroxide, iodosobenzene or ozone did not lead to any kind of “oxygen adduct” complex that could be spectroscopically observed. 相似文献
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Solvent diffusion in silica/poly[styrene‐co‐(acrylic acid)] core‐shell microspheres by pulsed field gradient NMR techniques 下载免费PDF全文
Binbo Jiang Yong Yang Lijun Du Carlos Mattea Jingdai Wang Siegfried Stapf Yongrong Yang 《应用聚合物科学杂志》2014,131(8)
Polymer‐coated SiO2 particles are prepared by precipitation of poly[styrene‐co‐(acrylic acid)] on SiO2 microspheres through an improved phase inversion method. The diffusion resistance of the polymer membrane was considered to be the critical reason for producing tailor‐made polyethylene by catalysts supported on these polymer‐coated particles. This paper employs pulsed field gradient NMR (PFG‐NMR) to distinguish diffusion of n‐hexane in different regimes, i.e., in the space between each particle, the pores in SiO2 and the polymer shell, by their respective diffusion coefficients. By varying the observation time, the time scale of the molecular exchange is discussed. A three‐region ansatz was used to interpret the exchange and diffusion in polymer‐coated SiO2 system, and was compared with results acquired with noncoated particles. At long diffusion times, the mean‐squared displacement, and thus the averaged self‐diffusion coefficient, of hexane in the system of polymer‐coated SiO2 particles is significantly reduced. The PSA membrane is identified as an efficient barrier against molecular exchange between the pores in SiO2 and the intraparticle space. Consistently, the relaxation measurements indicated that the mobility of n‐hexane molecules, especially the rotation of n‐hexane, was limited by the PSA membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40160. 相似文献
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Ralf-Peter Franke Anne Krüger Tim Scharnweber Folker Wenzel Friedrich Jung 《International journal of molecular sciences》2014,15(9):16134-16152
Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium—supplied by the left coronary artery—after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton. 相似文献
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Desloover J De Clippeleir H Boeckx P Du Laing G Colsen J Verstraete W Vlaeminck SE 《Water research》2011,45(9):2811-2821
New Activated Sludge (NAS®) is a hybrid, floc-based nitrogen removal process without carbon addition, based on the control of sludge retention times (SRT) and dissolved oxygen (DO) levels. The aim of this study was to examine the performance of a retrofitted four-stage NAS® plant, including on-line measurements of greenhouse gas emissions (N2O and CH4). The plant treated anaerobically digested industrial wastewater, containing 264 mg N L−1, 1154 mg chemical oxygen demand (COD) L−1 and an inorganic carbon alkalinity of 34 meq L−1. The batch-fed partial nitritation step received an overall nitrogen loading rate of 0.18-0.22 kg N m−3 d−1, thereby oxidized nitrogen to nitrite (45-47%) and some nitrate (13-15%), but also to N2O (5.1-6.6%). This was achieved at a SRT of 1.7 d and DO around 1.0 mg O2 L−1. Subsequently, anammox, denitrification and nitrification compartments were followed by a final settler, at an overall SRT of 46 d. None of the latter three reactors emitted N2O. In the anammox step, 0.26 kg N m−3 d−1 was removed, with an estimated contribution of 71% by the genus Kuenenia, which constituted 3.1% of the biomass. Overall, a nitrogen removal efficiency of 95% was obtained, yielding a dischargeable effluent. Retrofitting floc-based nitrification/denitrification with carbon addition to NAS® allowed to save 40% of the operational wastewater treatment costs. Yet, a decrease of the N2O emissions by about 50% is necessary in order to obtain a CO2 neutral footprint. The impact of emitted CH4 was 20 times lower. 相似文献
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Advanced Mutasynthesis Studies on the Natural α‐Pyrone Antibiotic Myxopyronin from Myxococcus fulvus 下载免费PDF全文
J. Henning Sahner Hilda Sucipto Dr. Silke C. Wenzel Dr. Matthias Groh Prof. Dr. Rolf W. Hartmann Prof. Dr. Rolf Müller 《Chembiochem : a European journal of chemical biology》2015,16(6):946-953
Myxopyronin is a natural α‐pyrone antibiotic from the soil bacterium Myxococcus fulvus Mx f50. Myxopyronin inhibits bacterial RNA polymerase (RNAP) by binding to a part of the enzyme not targeted by the clinically used rifamycins. This mode of action makes myxopyronins promising molecules for the development of novel broad‐spectrum antibacterials. We describe the derivatization of myxopyronins by an advanced mutasynthesis approach as a first step towards this goal. Site‐directed mutagenesis of the biosynthetic machinery was used to block myxopyronin biosynthesis at different stages. The resulting mutants were fed with diverse precursors that mimic the biosynthetic intermediates to restore production. Mutasynthon incorporation and production of novel myxopyronin derivatives were analyzed by HPLC‐MS/MS. This work sets the stage for accessing numerous myxopyronin derivatives, thus significantly expanding the chemical space of f α‐pyrone antibiotics. 相似文献
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