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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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The current popularity of backpack-type load carriage systems (LCS) by students has precipitated a prevalence of postural abnormalities and pain. This study compared subjective perceptual comfort in standard and vertically loaded LCSs. Sixteen females ages 18-23 years rated their personal LCSs for perceived shoulder, neck, and lower back comfort and for overall comfort, each day for two weeks using 100 mm visual analogue scales (VAS). Each scale contained polar extremities of 'very comfortable' to 'very uncomfortable' and a vertical mark placed on the 100 mm line by the participants indicated their perception of comfort. Following two weeks, participants were given LCSs that distributed the weight vertically and were asked to rate the system in the same way for an additional two-week period. Statistical analysis revealed significant differences in shoulder (p=0.015), neck (p=0.005), and lower back (p=0.036) comfort and overall comfort (p=0.001) between the participants' personal LCSs and the experimental LCS. In conclusion, vertical load placement may redistribute the load in a manner that reduces symptoms of selected anatomical discomfort. 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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