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921.
Ionic liquid, 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl), was used as solvent for the polymerization of acrylonitrile (AN) and the resulting polymer solution was directly applied for spinning to produce polyacrylonitrile (PAN) fiber for the first time. Acrylic polymers with high content of AN, large molecular weight, and low polydispersity index (PDI) were prepared. The PAN macromolecules have little degradation during dissolution of PAN in [BMIM]Cl, which is completely different from the dissolution of biopolymers such as cellulose in ionic liquids. The PAN fiber with round profile and good mechanical properties was successfully spun from the PAN/[BMIM]Cl solution using dry–jet wet spinning technology. It suggests that an environmental friendly process for the acrylic fiber would be developed and the high performance PAN fiber would be obtained when the spinning conditions are optimized further. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
922.
Cuihong Wan Meng Cui Fengrui Song Zhiqiang Liu Shuying Liu 《Journal of the American Society for Mass Spectrometry》2009,20(7):1281-1286
The GGA triplet repeats are widely dispersed throughout eukaryotic genomes. (GGA)n or (GGT)n oligonucleotides can interact
with double-stranded DNA containing (GGA:CCT)n to form triple-stranded DNA. The effects of 8 divalent metal ions (3 alkaline-earth
metals and 5 transition metals) on formation of these purine-rich triple-helix DNA were investigated by electrospray ionization
Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-MS). In the absence of metal ions, no triplex but single-strand,
duplex, and purine homodimer ions were observed in mass spectra. The triple-helix DNA complexes were observed only in the
presence of certain divalent ions. The effects of different divalent cations on the formation of purine-rich triplexes were
compared. Transition-metal ions, especially Co2+ and Ni2+, significantly boost the formation of triple-helix DNA, whereas alkaline-earth metal ions have no positive effects on triplex
formation. In addition, Ba2+ is notably beneficial to the formation of homodimer instead of triplex. 相似文献
923.
Yanuardi Raharjo Mohd Marsin Sanagi Wan Aini Wan Ibrahim Ahmedy Abu Naim Hassan Y. Aboul‐Enein 《Journal of separation science》2009,32(4):623-629
A liquid‐phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 μL) of isooctane as the acceptor phase was introduced continually to fill‐up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 μL) was first introduced into the hollow fiber and additional amounts (ca. 0.2 μL) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 μg/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples. 相似文献
924.
Qiuhua Nie Guoxiang Wang Xunsi Wang Mohamed Barj Tiefeng Xu Shixun Dai Jong Heo 《Journal of Non》2011,357(11-13):2362-2365
A systematic series of (100 ? x)(GeTe4.3) ? xCdI2/ZnI2 far infrared transmitting glasses were prepared by traditional melt-quenching method. ZnI2 (20 mol%) can be introduced in the glassy matrix, while only 10 mol% CdI2 can be incorporated in the Ge-Te-CdI2 glass system. Based on differential thermal analysis (DTA) data, most of the glass samples have good thermal stability. A maximum ΔT value of 115 °C was obtained for the glass composition 90(GeTe4.3)–10ZnI2. The allowed indirect transition optical band gap was calculated according to the classical Tauc equation. It is found that the indirect optical band gap decreased from 0.619 to 0.569 eV with the CdI2 addition and increased from 0.628 to 0.677 eV with the ZnI2 addition. According to infrared transmission spectra, the Ge-Te-CdI2/ZnI2 glasses show wide IR transparency. 相似文献
925.
Motivated by just-in-time manufacturing, we consider a single machine scheduling problem with dual criteria, i.e., the minimization of the total weighted earliness subject to minimum number of tardy jobs. We discuss several dominance properties of optimal solutions. We then develop a heuristic algorithm with time complexity O(n3) and a branch and bound algorithm to solve the problem. The computational experiments show that the heuristic algorithm is effective in terms of solution quality in many instances while the branch and bound algorithm is efficient for medium-size problems. 相似文献
926.
927.
Optimal proportional reinsurance and investment based on Hamilton-Jacobi-Bellman equation 总被引:1,自引:0,他引:1
In the whole paper, the claim process is assumed to follow a Brownian motion with drift and the insurer is allowed to invest in a risk-free asset and a risky asset. In addition, the insurer can purchase the proportional reinsurance to reduce the risk. The paper concerns the optimal problem of maximizing the utility of terminal wealth. By solving the corresponding Hamilton-Jacobi-Bellman equations, the optimal strategies about how to purchase the proportional reinsurance and how to invest in the risk-free asset and risky asset are derived respectively. 相似文献
928.
The Legendre spectral Galerkin method for the Volterra integral equations of the second kind is proposed in this paper. We
provide a rigorous error analysis for the proposed method, which indicates that the numerical errors (in the L
2 norm) will decay exponentially provided that the kernel function and the source function are sufficiently smooth. Numerical
examples are given to illustrate the theoretical results.
相似文献
929.
Gong JR Yan HJ Yuan QH Xu LP Bo ZS Wan LJ 《Journal of the American Chemical Society》2006,128(38):12384-12385
This communication provides a facile method for distributing and dispersing molecules within a molecular template. Using the self-assembled template of oligo(phenylene-ethynylene) (OPE), organic molecules such as coronene (COR) and biomolecules such as tripeptide are controllably distributed and dispersed within this molecular template on highly oriented pyrolytic graphite (HOPG) surfaces. COR molecules were controllably distributed into various regular arrays by simply adjusting the molecular molar ratio, while tripeptide molecules were uniformly positioned at the vacancies of the OPE template. 相似文献
930.
The reaction of 9-{[N-n-propyl-N-(diphenylphosphino)amino]methyl}anthracene (1) with Au(SMe2)Cl yields complex 2 with an arm-opening configuration. The latter is treated with AgClO4 to form complex 4 and then respectively reacted with acetonitrile, pyridine, and triphenylphosphine sulfide to afford novel gold(I) eta2-arene complexes 3a-c, which have arm-closing configurations and feeble or weak fluorescence emissions. The observation can be attributed to charge transfer from the anthracene unit to the Au+ ion. When the solution of 3a or 4 in CH2Cl2 was added with 1 equiv of Ph3P, complex 5 with the arm-opening configuration was formed and strong emission was restored. 相似文献