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41.
Mathematical Notes - The Boros–Moll polynomials $$P_m(a)$$ arise in the evaluation of a quartic integral. In the past few years, there has been some remarkable research on the properties of... 相似文献
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Jong-Shi Pang 《Mathematical Programming》1993,58(1-3):149-160
This paper is concerned with two well-known families of iterative methods for solving the linear and nonlinear complementarity problems. For the linear complementarity problem, we consider the class of matrix splitting methods and establish, under a finiteness assumption on the number of solutions, a necessary and sufficient condition for the convergence of the sequence of iterates produced. A rate of convergence result for this class of methods is also derived under a stability assumption on the limit solution. For the nonlinear complementarity problem, we establish the convergence of the Newton method under the assumption of a pseudo-regular solution which generalizes Robinson's concept of a strongly regular solution. In both instances, the convergence proofs rely on a common sensitivity result of the linear complementarity problem under perturbation.This work was based on research supported by the National Science Foundation under grant ECS-8717968. 相似文献
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Wong DM Greenblatt HM Dvir H Carlier PR Han YF Pang YP Silman I Sussman JL 《Journal of the American Chemical Society》2003,125(2):363-373
Acetylcholinesterase (AChE) inhibitors improve the cognitive abilities of Alzheimer patients. (-)-Huperzine A [(-)-HupA], an alkaloid isolated from the club moss, Huperzia serrata, is one such inhibitor, but the search for more potent and selective drugs continues. Recently, alkylene-linked dimers of 5-amino-5,6,7,8-tetrahydroquinolinone (hupyridone, 1a), a fragment of HupA, were shown to serve as more potent inhibitors of AChE than (-)-HupA and monomeric 1a. We soaked two such dimers, (S,S)-(-)-bis(10)-hupyridone [(S,S)-(-)-2a] and (S,S)-(-)-bis(12)-hupyridone [(S,S)-(-)-2b] containing, respectively, 10 and 12 methylenes in the spacer, into trigonal TcAChE crystals, and solved the X-ray structures of the resulting complexes using the difference Fourier technique, both to 2.15 A resolution. The structures revealed one HupA-like 1a unit bound to the "anionic" subsite of the active-site, near the bottom of the active-site gorge, adjacent to Trp84, as seen for the TcAChE/(-)-HupA complex, and the second 1a unit near Trp279 in the "peripheral" anionic site at the top of the gorge, both bivalent molecules thus spanning the active-site gorge. The results confirm that the increased affinity of the dimeric HupA analogues for AChE is conferred by binding to the two "anionic" sites of the enzyme. Inhibition data show that (-)-2a binds to TcAChE approximately 6-7- and > 170-fold more tightly than (-)-2b and (-)-HupA, respectively. In contrast, previous data for rat AChE show that (-)-2b binds approximately 3- and approximately 2-fold more tightly than (-)-2a and (-)-HupA, respectively. Structural comparison of TcAChE with rat AChE, as represented by the closely related mouse AChE structure (1maa.pdb), reveals a narrower gorge for rat AChE, a perpendicular alignment of the Tyr337 ring to the gorge axis, and its conformational rigidity, as a result of hydrogen bonding between its hydroxyl group and that of Tyr341, relative to TcAChE Phe330. These structural differences in the active-site gorge explain the switch in inhibitory potency of (-)-2a and 2b and the larger dimer/(-)-HupA potency ratios observed for TcAChE relative to rat AChE. The results offer new insights into factors affecting protein-ligand complementarity within the gorge and should assist the further development of improved AChE inhibitors. 相似文献
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Qiong Ye Hong Zhao Xiang Xue Shie-Ming Pang 《Journal of organometallic chemistry》2005,690(2):286-290
Solvothermal treatments of W(CO)6 with 2,2′-bipyridine and 1,10-phenanthroline give [W(CO)4(bipy)] (1) and [W(CO)4(phen)] (2), respectively, which both crystallize in noncentrosymmetric space groups, suggesting that they meet the requirement of second harmonic generation (SHG) investigations. The preliminary experiment indicates that they are SHG active, and approximately estimated to be that of urea. 相似文献
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The covalent immobilization of DNA onto self-assembled monolayer (SAM) modified gold electrodes (SAM/Au) was studied by X-ray photoelectron spectrometry and electrochemical method so as to optimize its covalent immobilization on SAMs. Three types of SAMs with hydroxyl, amino, and carboxyl terminal groups, respectively, were examined. Results obtained by both X-ray photoelectron spectrometry and cyclic voltammetry show that the largest covalent immobilization amount of dsDNA could be gained on hydroxyl-terminated SAM/Au. The ratio of amount of dsDNA immobilized on hydroxyl-terminated SAMs to that on carboxyl-terminated SAMs and to that on amino-terminated SAMs is (3-3.5): (1-1.5): 1. The dsDNA immobilized covalently on hydroxyl-terminated SAMs accounts for 82.8-87.6% of its total surface amount (including small amount of dsDNA adsorbed). So the hydroxyl-terminated SAM is a good substrate for the covalent immobilization of dsDNA on gold surfaces. 相似文献
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Yuyin Wang Yan Wang Li Zhang Prof. Dr. Chun‐Sen Liu Prof. Dr. Huan Pang 《化学:亚洲杂志》2019,14(16):2790-2795
To realize the effective conversion of renewable energy through water decomposition, efficient electrocatalysts for the oxygen evolution reaction (OER) are essential. In this article, PBA@POM was successfully prepared with a Prussian blue analogue (PBA) as the initial structure. A facile hydrothermal process is reported for obtaining PBA@POM by etching the cubic PBA with a strong Brønsted acid, H3PMo12O40 (HPMo). The hollow cube structure not only exposes more active sites but also promotes electron transport, which results in excellent electrocatalytic activity for the OER. Compared with the PBA, which initially simply adhered to POM, the optimum PBA@POM hybrids display remarkably enhanced OER catalytic activity, with an almost constant overpotential of 440 mV at a current density of 10 mA cm?2 and a small Tafel slope (23.45 mV dec?1). The facilely prepared PBA@POM with good electrochemical activity and stability promises great potential for the OER. 相似文献