能动抛光磨盘的变形实验研究

 能动抛光磨盘实时产生不同的表面变形，在对大口径非球面光学元件进行精磨和抛光时实现与工件表面良好的大尺寸吻合，可以消除传统光学加工采用小尺寸磨头时带来的高频残余误差并提高加工效率。以加工直径1.3m左右，F/2的抛物面光学元件为例，对能动磨盘在不同离轴度时能够产生的变形进行了计算和实验。结果表明，能动磨盘能够以较高精度产生旋转对称或非对称的抛物面形状。对能动磨盘产生变形后的残余误差进行了分析。     

Metabolomics reveals hippocampal metabolic fluctuations of postoperative fatigue syndrome and anti‐fatigue effect of Carthamus tinctorius L. extract in rat model

Postoperative fatigue syndrome (POFS) is a common clinical complication following almost every major abdominal surgery. There is not a full explanation of the etiology of POFS, especially its central mechanism. Carthamus tinctorius L. is a classic traditional Chinese medicine (TCM) which could exert ananti‐fatigue effect on POFS. However, its mechanism is still lacking. Here, ultra‐high performance liquid chromatography coupled with a quadrupole time‐of‐flight mass spectrometry (UHPLC‐Q‐TOFMS) based metabonomic approach was used to characterize hippocampal metabolic fluctuations of POFS in a rat model induced by partial hepatectomy, and to evaluate the anti‐fatigue effect of C. tinctorius L. extract (CTLE). With partial least‐squares discriminant analysis for classification and selection of biomarkers, 15 hippocampal metabolites related to POFS were identified, primarily involving alanine, aspartate and glutamate metabolism, valine, leucine and isoleucine degradation, purine metabolism, phenylalanine metabolism, tryptophan metabolism, phospholipid metabolism and fatty acid metabolism. With these altered metabolic pathways as possible drug targets, we systematically analyzed the protective effect of CTLE, which showed that CTLE could provide an anti‐fatigue effect on POFS through partially regulating the perturbed metabolic pathways. This study indicated that UHPLC‐Q‐TOFMS‐based metabolomics provided a powerful tool to reveal hippocampal metabolic fluctuations of POFS and study the mechanism of TCM. Copyright © 2015 John Wiley & Sons, Ltd.     

Periodic solutions for second order singular damped differential equations

We study the existence of positive periodic solutions for second order singular damped differential equations by combining the analysis of the sign of Green?s functions for the linear damped equation, together with a nonlinear alternative principle of Leray–Schauder. Recent results in the literature are generalized and significantly improved.     

Rh-Catalyzed Decarbonylative Cross-Coupling between o-Carboranes and Twisted Amides: A Regioselective,Additive-Free,and Concise Late-Stage Carboranylation

The convenient cross-coupling of sp² or sp³ carbons with a specific boron vertex on carborane cage represents significant synthetic values and insurmountable challenges. In this work, we report an Rh-catalyzed reaction between o-carborane and N-acyl-glutarimides to construct various B_cage−C bonds. Under the optimized condition, the removable imine directing group (DG) leads to B(3)− or B(3,6)−C couplings, while the pyridyl DG leads to B(3,5)−Ar coupling. In particular, an unexpected rearrangement of amide reagent is observed in pyridyl directed B(4)−C(sp³) formation. This scalable protocol has many advantages, including easy access, the use of cheap and widely available coupling agents, no requirement of an external ligand, base or oxidant, high efficiency, and a broad substrate scope. Leveraging the Rh^I dimer and twisted amides, this method enables straightforward access to diversely substituted and therapeutically important carborane derivatives at boron site, and provides a highly valuable vista for carborane-based drug screening.     

A Practical Total Synthesis of Taxamairin B

Taxamairin B. a novel rearranged 9(10 ± 20)-abeo-8. 11. 13-triene diterpenoid. has been convergently synthesized by a facile route, which employed the acid catalyzed rearrangement and oxidation of vinyl carbinol as the key steps.