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Marie-Louise Wind Beatrice Braun-Cula Fabian Schax Christian Herwig Prof. Christian Limberg 《Israel journal of chemistry》2020,60(10-11):1057-1060
The isolation and identification of intermediates formed in the course of the activation of dioxygen at transition metal centers reveals important mechanistic insights concerning such processes. We previously reported the reaction of the dinuclear CrII complex [L2Cr2(MeCN)2][Li(MeCN)]2 (L=PhSi(OSiPh2O−)3) ( 5 ) with dioxygen, which resulted in the formation of the CrIV oxo complex [L2Cr2O2][Li(THF)2]2 ( 6 ), as the final room temperature stable product. Here we now report the isolation and characterization of an intermediate en route to 6 , namely the dinuclear CrIII superoxo complex [L2Cr2(O2)2][Li(MeCN)]2 ( 7 ). 7 is the first example of a structurally characterized dinuclear CrIII superoxo complex with two independent side-on bound superoxo ligands. Reactivity studies outline the capability of this superoxo complex to activate weak O−H bonds. 相似文献
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Gerhard?Sinn Herwig?MayerEmail author Stefanie?Stanzl-Tschegg 《Journal of Materials Science》2005,40(16):4325-4332
Surfaces created by ultrasonic-assisted cutting (UC) of beech and spruce and of medium density fibreboard (MDF) are compared to surfaces obtained by conventional linear cutting (CC) using a sharp tool. Topography is evaluated performing roughness measurements and scanning electron microscopy. No effect of UC procedure on mean roughness is found. The surface of MDF and large areas of the surfaces of the woods appear similar after UC and CC, whereas other regions show impact marks and microscopic reels produced by the periodic oscillation of the tool in UC. The wettability of surfaces produced with both wood processing techniques is similar. Surface free energy measurements indicate accelerated ageing caused by UC, probably due to heating. 相似文献
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Arnar ��lafsson Bj?rn T��r J��nsson Laurent Amsaleg Herwig Lejsek 《Multimedia Systems》2011,17(2):83-100
In recent years, some approximate high-dimensional indexing techniques have shown promising results by trading off quality
guarantees for improved query performance. While the query performance and quality of these methods has been well studied,
however, the performance of index maintenance has not yet been reported in any detail. Here, we focus on the dynamic behavior
of the balanced NV-tree, which is a disk-based approximate index for very large collections. We report on an initial study
of the effects of several implementation choices for the balanced NV-tree, and show that with appropriate implementation,
significant performance improvements are possible. Overall, the proposed techniques not only reduce maintenance cost, but
can also improve search performance significantly with minimal loss of search quality. 相似文献
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Microorganisms are exposed to fast changes in microenvironment in large scale bioreactors. Because of their fast response to the changes, overall performance of biological system in small scale differs from large scale. Hence the variations in the environment that microorganisms are living in are mimicked in small scale. For this purpose one way is to feed substrate into the bioreactor in an oscillatory profile. In this work two different types of triangular oscillatory feeding profiles were applied as the post induction feeding strategy in intracellular recombinant alkaline phosphatase production expressed in Escherichia coli to find out if this biological system behaves in inhomogeneous environment differently. On line and offline measurements provide evaluation of product quality and quantity. Then the results of the experiments were compared with those of the control run at which constant feeding rate was executed. The results showed that oscillatory feeding at which cells were not starved led to higher yield of protein per substrate (0.027 C-mol/C-mol) and higher activity per protein (0.79 U/mg) when compared to a constant feeding rate (0.011 C-mol/C-mol and 0.11 U/mg). 相似文献
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H. Herwig 《Forschung im Ingenieurwesen》2007,71(2):107-112
The present article is not meant as a refreshment course in thermodynamics but addresses those readers who always had their problems with enthalpy and its physical meaning. It is the intention to show that enthalpy combines two quantities which often are very different in character. This makes the physical interpretation difficult and often is misleading. 相似文献