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排序方式: 共有210条查询结果,搜索用时 703 毫秒
21.
Effects of temperature on self‐interaction of human‐like collagen (HLC) were investigated by hydrophobic interaction chromatography, calorimetric measurement, and sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis. Results show that three types of interaction roles may exist between HLC molecules at 3–50°C, which were divided into three narrower temperature ranges. In temperature range from 3–22°C, hydrogen bonding plays a key role in the formation of a gelatinous aggregate. In the range of 22–38°C, hydrophobic bonds accompanied by hydrogen bonds are involved in the formation compact aggregates. When temperature is above 38°C the hydrophobic effect formed in the HLC monomer results in the loss of its ability to self‐interact. 相似文献
22.
We propose a new self-adaptive Levenberg-Marquardt algorithm for the system of nonlinear equations F(x) = 0. The Levenberg-Marquardt parameter is chosen as the product of ‖Fk‖δ with δ being a positive constant, and some function of the ratio between the actual reduction and predicted reduction of
the merit function. Under the local error bound condition which is weaker than the nonsingularity, we show that the Levenberg-Marquardt
method converges superlinearly to the solution for δ∈ (0, 1), while quadratically for δ∈ [1, 2]. Numerical results show that the new algorithm performs very well for the nonlinear equations with high rank deficiency.
This work is supported by Chinese NSFC grants 10401023 and 10501013, Research Grants for Young Teachers of Shanghai Jiao Tong
University, and E-Institute of Shanghai Municipal Education Commission, N. E03004. 相似文献
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24.
<正>YAG:Ce crystal with a diameter of 110 mm is successfully grown by the temperature gradient technique (TGT).The effects of annealing on the luminescence efficiency of YAG:Ce crystal are investigated,and the optimal annealing temperature and atmosphere are obtained.The mechanism of variation behavior of the luminescence efficiency of YAG:Ce under different annealing conditions is discussed and some details on the luminescence associated with color centers are analyzed. 相似文献
25.
Jianyu Tong Yi Shi Guhuan Liu Tao Huang Na Xu Zhengguang Zhu Yuanli Cai 《Macromolecular rapid communications》2013,34(23-24):1827-1832
The attempts to mediate iterative RAFT polymerization of ionic monomers through visible light irradiation in water at 20 °C is reported, in which complete conversions are attained in several tens of minutes and the propagation suspends/restarts immediately for multiple times on cycling irradiation. This technique suits the one‐pot synthesis of NH2/imidazole‐based polymers with tuned structures from homo to random, block, random‐block, and block‐random‐block, thus is robust and promising to control the sequence of the ionized water‐soluble reactive copolymers.
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27.
Modified High‐Nickel Cathodes with Stable Surface Chemistry Against Ambient Air for Lithium‐Ion Batteries 下载免费PDF全文
Dr. Ya You Dr. Hugo Celio Jianyu Li Dr. Andrei Dolocan Prof. Dr. Arumugam Manthiram 《Angewandte Chemie (International ed. in English)》2018,57(22):6480-6485
High‐Ni layered oxides are promising next‐generation cathodes for lithium‐ion batteries owing to their high capacity and lower cost. However, as the Ni content increases over 70 %, they have a high dynamic affinity towards moisture and CO2 in ambient air, primarily reacting to form LiOH, Li2CO3, and LiHCO3 on the surface, which is commonly termed “residual lithium”. Air exposure occurs after synthesis as it is common practice to handle and store them under ambient conditions. The air exposure leads to significant performance losses, and hampers the electrode fabrication, impeding their practical viability. Herein, we show that substituting a small amount of Al for Ni in the crystal lattice notably improves the chemical stability against air by limiting the formation of LiOH, Li2CO3, LiHCO3, and NiO in the near‐surface region. The Al‐doped high‐Ni oxides display a high capacity retention with excellent rate capability and cycling stability after being exposed to air for 30 days. 相似文献
28.
Xinyuan He Jianyu Zhang Xinyue Liu Zhuwei Jin Dr. Jacky W. Y. Lam Prof. Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300353
Functional materials with multi-responsive properties and good controllability are highly desired for developing bioinspired and intelligent multifunctional systems. Although some chromic molecules have been developed, it is still challenging to realize in situ multicolor fluorescence changes based on a single luminogen. Herein, we reported an aggregation-induced emission (AIE) luminogen called CPVCM, which can undergo a specific amination with primary amines to trigger luminescence change and photoarrangement under UV irradiation at the same active site. Detailed mechanistic insights were carried out to illustrate the reactivity and reaction pathways. Accordingly, multiple-colored images, a quick response code with dynamic colors, and an all-round information encryption system were demonstrated to show the properties of multiple controls and responses. It is believed that this work not only provides a strategy to develop multiresponsive luminogens but also develops an information encryption system based on luminescent materials. 相似文献
29.
Yang R Jin J Chen Y Shao N Kang H Xiao Z Tang Z Wu Y Zhu Z Tan W 《Journal of the American Chemical Society》2008,130(26):8351-8358
We report an effective, novel self-assembled single-wall carbon nanotube (SWNT) complex with an oligonucleotide and demonstrate its feasibility in recognizing and detecting specific DNA sequences in a single step in a homogeneous solution. The key component of this complex is the hairpin-structured fluorescent oligonucleotide that allows the SWNT to function as both a "nanoscaffold" for the oligonucleotide and a "nanoquencher" of the fluorophore. Given this functionality, this carbon nanotube complex represents a new class of universal fluorescence quenchers that are substantially different from organic quenchers and should therefore have many applications in molecular engineering and biosensor development. Competitive binding of a DNA target and SWNTs with the oligonucleotide results in fluorescence signal increments relative to the fluorescence without a target as well as in marked fluorescence quenching. In contrast to the common loop-and-stem configuration of molecular beacons (MBs), this novel fluorescent oligonucleotide needs only one labeled fluorophore, yet the emission can be measured with little or no background interference. This property greatly improves the signal-to-background ratio compared with those for conventional MBs, while the DNA-binding specificity is still maintained by the MB. To test the interaction mechanisms of the fluorescent oligonucleotide with SWNTs and target DNA, thermodynamic analysis and fluorescence anisotropy measurements, respectively, were applied. Our results show that MB/SWNT probes can be an excellent platform for nucleic acid studies and molecular sensing. 相似文献
30.
Daohong Liao Shaoqiang Yang Jianyu Wang Jian Zhang Benke Hong Fan Wu Prof. Dr. Xiaoguang Lei 《Angewandte Chemie (International ed. in English)》2016,55(13):4291-4295
The increase and spread of Gram‐negative bacteria that resistant are to almost all currently available β‐lactam antibiotics is a major global health problem. The primary cause for drug resistance is the acquisition of metallo‐β‐lactamases such as metallo‐β‐lactamase‐1 (NDM‐1). The fungal natural product aspergillomarasmine A (AMA), a fungal natural product, is an inhibitor of NDM‐1 and has shown promising in vivo therapeutic potential in a mouse model infected with NDM‐1‐expressing Gram‐negative bacteria. The first total synthesis and stereochemical configuration reassignment of aspergillomarasmine A is reported. The synthesis highlights a flexible route and an effective strategy to achieve the required oxidation state at a late stage. This modular route is amenable to the efficient preparation of analogues for the development of metallo‐β‐lactamase inhibitors to potentiate β‐lactam antibiotics. 相似文献