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本文提出了一个指数型凸化,凹化变换,并证明了单调非线性规划总能变换成相应的凹规划或凸规划.还证明了带某种类型线性或非线性约束的非线性规划在适当条件下能变换成单调非线性规划. 相似文献
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In this work, we report a simple approach for controllable synthesis of one-dimensional (1D) gold nanoparticle (AuNP) assemblies in solution. In the presence of divalent metallic ions, poly(acrylic acid)-1-dodecanethiol-stabilized AuNPs (PAA-DDT@AuNPs) are found to form 1D assemblies in aqueous solution by an ion-templated chelation process; this causes an easily measurable change in the absorption spectrum of the particles. The assemblies are very stable and remain suspended in solution for more than one month without significant aggregation. The morphologies of these 1D assemblies are dependent on the concentration of metallic cations in the solution. While lower concentrations led to the formation of particle dimers, higher concentrations generated long nanoparticle chain networks. In addition, the effect of EDTA, the solution pH, and the size of the PAA-DDT@AuNPs is also studied for further exploration of the mechanism of the formation of the 1D assemblies. 相似文献
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In this article, we propose a Cucker–Smale‐type self‐propelled particle model with continuous non‐Lipschitz protocol. We show that the flocking can occur in finite time if the communication rate function satisfies a lower bound condition. Both our theoretical and numerical results uncover a power‐law relationship between the convergence time and the number of individuals. Our result implies that the individuals in groups with high density can transit rapidly to ordered collective motion. We also investigate the influence of control parameter on the convergence speed. © 2015 Wiley Periodicals, Inc. Complexity 21: 354–361, 2016 相似文献
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The steady shear behavior of metallo-supramolecular polymer networks formed by bis-Pd(II) cross-linkers and semidilute entangled solutions of poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) or N,N-dimethyl formamide (DMF) is reported. The steady shear behavior of the networks depends on the dissociation rate and association rate of the cross-linkers, the concentration of cross-linkers, and the concentration of the polymer solution. The divergent steady shear behavior-shear thinning versus shear thickening-of samples with identical structure but different cross-linker dynamics (J. Phys. Chem. Lett. 2010, 1, 1683-1686) is further explored in this paper. The divergent steady shear behavior for networks with different cross-linkers is connected to a competition between different time scales: the average time that a cross-linker remains open (τ(1)) and the local relaxation time of a segment of polymer chain (τ(segment)). When τ(1) is larger than τ(segment), shear thickening is observed. When τ(1) is smaller than τ(segment), only shear thinning is observed. 相似文献
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Comellas G Lemkau LR Zhou DH George JM Rienstra CM 《Journal of the American Chemical Society》2012,134(11):5090-5099
α-Synuclein (AS) fibrils are the main protein component of Lewy bodies, the pathological hallmark of Parkinson's disease and other related disorders. AS forms helices that bind phospholipid membranes with high affinity, but no atomic level data for AS aggregation in the presence of lipids is yet available. Here, we present direct evidence of a conversion from α-helical conformation to β-sheet fibrils in the presence of anionic phospholipid vesicles and direct conversion to β-sheet fibrils in their absence. We have trapped intermediate states throughout the fibril formation pathways to examine the structural changes using solid-state NMR spectroscopy and electron microscopy. The comparison between mature AS fibrils formed in aqueous buffer and those derived in the presence of anionic phospholipids demonstrates no major changes in the overall fibril fold. However, a site-specific comparison of these fibrillar states demonstrates major perturbations in the N-terminal domain with a partial disruption of the long β-strand located in the 40s and small perturbations in residues located in the "non-β amyloid component" (NAC) domain. Combining all these results, we propose a model for AS fibrillogenesis in the presence of phospholipid vesicles. 相似文献