与高阶导数有公共不动点的整函数

本文证明了如果f是非常数整函数满足超级σ_2(f)<1/2,k是一正整数,如果f和f(k)有公共不动点z CM,那么f~((k))(z)-z=c(f(z)-z),其中c是非零常数.     

Novel 1‐D Chains Constructed of Rings Which Include Six Metal Atoms [M2Au4] (M = Ni,Zn) with Aurophilic Interactions: Structure,Magnetic, and Spectral Studies

Two novel 1‐D chain complexes of a formal iminomethyl nitroxide radical [M(tpyimo)₂]₂[Au(CN)₂]₄ (M = Ni, Zn for 1 and 2 , typimo = 4,5‐dihydro‐4,4,5,5‐tetramethyl‐2‐(pyridin‐2‐yl)‐1H‐imidazol‐1‐yloxy), were synthesized and structurally characterized. Both 1‐D chains consist of two kinds of chair‐conformation rings, which include six metal atoms [M₂Au₄] (M = Ni, Zn), and are connected to each other alternately through aurophilic interactions. On the other hand, [Au(CN) ]₄ oligomers are also formed through aurophilic interactions, and used as bridges in the 1‐D chains. The magnetic coupling between the Ni^II ion and the tpyimo radical in 1 is a strong ferromagnetic interaction. Strong ligand‐centered luminescence is observed at room temperature for both complexes.     

Role of topology, nonadditivity, and water-mediated interactions in predicting the structures of alpha/beta proteins

The folding of alpha/beta proteins involves most of the commonly known structural and dynamic complexities of the protein energy landscapes. Thus, the interplay among different structural components, taking into account the cooperative interactions, is important in determining the success of protein structure prediction. In this work we present further developments of our knowledge-based force field for alpha/beta proteins, introducing more realistic modeling of many-body interactions governing the folding of beta-sheets. The model's innovations highlight both specific topological characteristics of secondary structures and the generic nonadditive interactions that are mediated by water. We also investigate how a coarse biasing of the protein morphology can be used to understand the role of heterogeneity in protein collapse. Analysis of the simulation results for three test alpha/beta proteins indicates that the addition of the topological and many-body ingredients to the model helps to greatly reduce the roughness in the energy landscape. Consequently, high quality candidate structures for alpha/beta proteins can be generated from simulated annealing runs, using very modest amounts of computer time.     

Selective heterogeneous nucleation and growth of size-controlled metal nanoparticles on carbon nanotubes in solution

We present a novel approach to the in situ deposition of size-controlled platinum nanoparticles on the exterior walls of carbon nanotubes (CNTs). The reduction of metal ions in ethylene glycol (EG), by the addition of a salt such as sodium dodecyl sulfate (SDS), p-CH3C6H4SO3Na, LiCF3SO3, or LiClO4, results in high dispersions and high loadings of platinum nanoparticles on CNTs without aggregation. We have performed controlled experiments to elucidate the mechanism. By exploiting the salt effect, our method effectively depresses homogeneous nucleation, leading to selective heterogeneous metal nucleation and growth, even on unmodified CNTs. In the 2.3-9.6 nm size range, the size of platinum nanoparticles, at 50% loading, can be controlled by changing the concentration of metal ions, the reaction temperature, the reducing reagent or the means by which reactive solutions are added. Our method provides a flexible route towards the preparation of novel one-dimensional hybrid materials, for which a number of promising applications in a variety of fields can be envisioned.     

Selenium-coated carbon electrode for anodic stripping voltammetric determination of copper(II)

We describe a new and promising type of selenium film electrode for anodic stripping voltammetry. This method is based on formation of copper selenide onto an in-situ formed selenium-film carbon electrode, this followed by Osteryoung square-wave anodic stripping voltammetry. Copper(II) is also in-situ electroplated in a test solution containing 0.01 mol L^-1 hydrochloric acid, 0.05 mol L^?1 potassium chloride and 500 µg L^?1 Se(IV) at a deposition potential of ?300 mV. The well-defined anodic peak current observed at about 200 mV is directly proportional to the Cu(II) concentration over the range from 1.0 to 100 µg L^?1 under the optimized conditions. The detection limit (three sigma level) is 0.2 µg L^?1 Cu(II) at 180 s deposition time. Relatively less interferences are shown from most of metal ions except for antimony(III). The method can be applied to analyses of river water and oyster tissue with good accuracy.     

Antibacterial mechanism of houttuyfonate homologues against Bacillus subtilis

In this study the effects of houttuyfonate homologues (HOU-C_n) on the surface and shape, the lipid fluidity and the protein conformation, the fatty acid compositions and fatty acid synthase II (FAS II) of B. subtilis were studied to elucidate the antibacterial mechanism of HOU-C_n against Bacillus subtilis. The scanning electronic microscope (SEM) results showed that the glycocalyx on the surface of B. subtilis disappeared and the cell became smaller after being treated with HOU-C_n. During the co-incubation of HOU-C_n and B. subtilis, HOU-C_n was decomposed into alkyl acyl aldehyde and sodium sulfite rapidly. Then alkyl acyl aldehyde was congregated onto cell membrane and inserted into lipid bilayer, further increased the fluidity of membrane and changed the conformation of membrane protein by hydrophobic binding. Subsequently, HOU-C_n inhibited the FAS II activity, and decreased the synthesis of fatty acids, especially increased the percentage of saturated fatty acid. HOU-C_n showed a strong antibacterial activity against G⁺-bacteria by a multi-target antibacterial mechanism.     

Optimal control of a nonlinear parabolic–elliptic system

In this paper, we shall study the problem of optimal control of the parabolic–elliptic system

_ut+_(f(t,x,u))x+g(t,x,u)+_Px−_(a(t,x)ux)x=_f0+B^∗ν$u_t+{\left(f(t,x,u)\right)}_x+g(t,x,u)+P_x-{\left(a(t,x)u_x\right)}_x=f_0+B^{\ast }\nu$

Ester Hydrolysis by a Cyclodextrin Dimer Catalyst with a Tridentate N,N′,N′′‐Zinc Linking Group

A new β‐cyclodextrin dimer, 2,6‐dimethylpyridine‐bridged‐bis(6‐monoammonio‐β‐cyclodextrin) (pyridyl BisCD, L), is synthesized. Its zinc complex (ZnL) is prepared, characterized, and applied as a catalyst for diester hydrolysis. The formation constant (log K_ML=7.31±0.04) of the complex and deprotonation constant (pK_a1=8.14±0.03, pK_a2=9.24±0.01) of the coordinated water molecule were determined by a potentiometric pH titration at (25±0.1)°C, indicating a tridentate N,N′,N′′‐zinc coordination. Hydrolysis kinetics of carboxylic acid esters were determined with bis(4‐nitrophenyl)carbonate (BNPC) and 4‐nitrophenyl acetate (NA) as the substrates. The resulting hydrolysis rate constants show that ZnL has a very high rate of catalysis for BNPC hydrolysis, yielding an 8.98×10³‐fold rate enhancement over uncatalyzed hydrolysis at pH 7.00, compared to only a 71.76‐fold rate enhancement for NA hydrolysis. Hydrolysis kinetics of phosphate esters catalyzed by ZnL are also investigated using bis(4‐nitrophenyl)phosphate (BNPP) and disodium 4‐nitrophenyl phosphate (NPP) as the substrates. The initial first‐order rate constant of catalytic hydrolysis for BNPP was 1.29×10^?7 s^?1 at pH 8.5, 35 °C and 0.1 mM catalyst concentration, about 1600‐fold acceleration over uncatalyzed hydrolysis. The pH dependence of the BNPP cleavage in aqueous buffer was shown as a sigmoidal curve with an inflection point around pH 8.25, which is nearly identical to the pK_a value of the catalyst from the potentiometric titration. The k_BNPP of BNPP hydrolysis promoted by ZnL is found to be 1.68×10^?3 M ^?1 s^?1, higher than that of NPP, and comparatively higher than those promoted by its other tridentate N,N′,N′′‐zinc analogues.     

一种基于单元型红外光谱辐射计的成像光谱数据获取系统设计

依据单元非成像型光谱辐射计的特点,提出了一种单元非成像型红外光谱辐射计的成像光谱数据获取系统.该系统采用在光谱辐射计前端加装扣描装置.结合同步控制器,实现光谱辐射计的空间扫描.利用光谱辐射计提供的接口,完成了采集获得的成像光谱数据的批量定标.该系统可达到500×500像素的空间分解能力,光谱范围667～5 000 cm-1,光谱分辨率为1 cm-1,空间视场角为150°,瞬时视场角为0.3°.将该系统应用于实际的场景光谱数据获取,通过对得到的实验数据分析和比较,说明本文给出的基于非成像光谱辐射计的成像数据获取系统,能够实现实际场景的成像光谱数据获取,能够满足实时性要求不太高的成像光谱数据获取.     

一类非线性相对转动动力系统的平衡稳定性及组合谐波近似解

建立一类含广义非线性弹性力的两质量相对转动系统的非线性动力学方程. 应用变量梯度法构造李雅普诺夫函数,研究相对转动非线性自治系统的稳定性. 应用摄动法求得相对转动非线性非自治系统在两种不同频率谐波共同激励下的组合谐波响应的近似解. 关键词： 相对转动 非线性动力系统 稳定性 组合谐波响应