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991.
Abstract A new flow‐injection online reduction electrochemical hydride generation system for the determination of Se(IV) and Se(VI) by atomic fluorescence spectrometry (AFS) was developed. In the system, an electromagnetic induction oven was used as heating resource to reduce Se(VI) to Se(IV) and a homemade tubular electrolytic cell as hydride generator. All analytical procedures were automatically controlled by a computer. The conditions of online reduction, including temperature, HCl concentration, and reduction time, have been studied in detail. The detection limits (3σ) of Se(IV) and Se(VI) in aqueous solution were 0.26 µg L?1 and 0.23 µg L?1, respectively. The precision for 11 replicate measurements of 50 µg L?1 Se(IV) and Se(VI) was 2.2% and 2.5%. This proposed method has been applied to the determination of Se(IV) and Se(VI) in springwater samples. 相似文献
992.
993.
Zhen Li 《中国科学:化学(英文版)》2017,60(8):1107-1108
正Undoubtedly,the realization of"one stone and two birds"is ideal,which is also applicable to the molecular design in the pursuit of excellent performance.Recently,this standpoint has been confirmed again by an interesting story written from the lab of Zujin Zhao,Shi-Jian Su,and BenZhong Tang,at South China University of Technology and the Hong Kong University of Science and Technology,in the design of DBT-BZ-DMAC(Figure 1)[1].Despite its simple structure,DBT-BZ-DMAC exhibits wonderful characteristics, 相似文献
994.
Fine tuning the assembly and gel behaviors of PEGylated polypeptide conjugates by the copolymerization of l‐alanine and γ‐benzyl‐l‐glutamate N‐carboxyanhydrides 下载免费PDF全文
Yumin Zhang Huijuan Song Hao Zhang Pingsheng Huang Jinjian Liu Liping Chu Jianfeng Liu Weiwei Wang Zhen Cheng Deling Kong 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1512-1523
Tuning the secondary structure of polypeptide is an effective strategy to modulate the assembly behaviors of polypeptide‐based copolymers. In this study, ring‐opening polymerization of l ‐alanine (Ala) and γ‐benzyl‐l ‐glutamate (BLG) N‐carboxyanhydrides was adopted using mPEG‐NH2 as the initiator to prepare mPEG‐poly(l ‐alanine‐co‐γ‐benzyl‐l ‐glutamate) (PEAB) copolymers with various Ala to BLG ratios. 1H NMR spectra and GPC test confirmed their well‐defined chemical structures. FT‐IR spectra indicated that at the powder state, all copolymers adopted both β‐sheet and α‐helical conformations. With the content of PBLG increased, the crystallization temperature and melting points of PEAB copolymers first rose then fell indicated by DSC curves. The self‐assembly of PEAB copolymers in dilute aqueous solution studied by DLS, TEM and circular dichroism spectra showed that PEAB copolymers self‐assembled into nanostructures with diverse morphologies and sizes due to distinct polypeptide conformations. Rheological analysis indicated that the alteration of the polypeptide composition can effectively modulate the modulus of PEAB assemblies in concentrated solutions. In all, copolymerization of two hydrophobic amino acid N‐carboxyanhydrides into the polypeptide block maybe an effective approach for modulating the assembly properties of PEGylated polypeptide. Besides, nanosilver‐encapsulated PEA or PEAB hydrogel showed promising antibacterial effect against Staphylococcus aureus and Bacillus subtillis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1512–1523 相似文献
995.
Wei Lin Xizhe Li Zhengming Yang Juan Wang Shengchun Xiong Yutian Luo Guoming Wu 《Transport in Porous Media》2017,120(1):227-238
In order to further improve the accuracy of digital core modeling, a new hybrid method was proposed to construct the dual pore 3-D digital core with high precision. First of all, 3-D macro-pore digital cores were constructed by micro-CT. Secondly, based on the high-resolution 2-D scanning electron microscopy images of rock cores, micro-pore digital cores were constructed by simulated annealing method. And then, a superposition method was used to construct the digital core which could describe different pore characteristics. Finally, pore structures of digital cores were compared, and lattice Boltzmann method was used to analyze the percolation properties. The results show that the carbonate dual pore digital core constructed by the new hybrid method has a high accuracy, which can capture the pore properties of both macro-pore and micro-pore, and whose permeability simulation results are in good agreement with the experimental measurements. In addition, the new hybrid method is not only accurate and reliable, but also high efficient and economic, and can be applied to all kinds of reservoir modeling. 相似文献
996.
Non‐intrusive reduced‐order modeling for multiphase porous media flows using Smolyak sparse grids 下载免费PDF全文
Dunhui Xiao Zhi Lin Fangxin Fang Christopher C. Pain Ionel M. Navon Pablo Salinas Ann Muggeridge 《国际流体数值方法杂志》2017,83(2):205-219
In this article, we describe a non‐intrusive reduction method for porous media multiphase flows using Smolyak sparse grids. This is the first attempt at applying such an non‐intrusive reduced‐order modelling (NIROM) based on Smolyak sparse grids to porous media multiphase flows. The advantage of this NIROM for porous media multiphase flows resides in that its non‐intrusiveness, which means it does not require modifications to the source code of full model. Another novelty is that it uses Smolyak sparse grids to construct a set of hypersurfaces representing the reduced‐porous media multiphase problem. This NIROM is implemented under the framework of an unstructured mesh control volume finite element multiphase model. Numerical examples show that the NIROM accuracy relative to the high‐fidelity model is maintained, whilst the computational cost is reduced by several orders of magnitude. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
997.
Suppression of the Charge Density Wave State in Two-Dimensional 1T-TiSe2 by Atmospheric Oxidation 下载免费PDF全文
Lifei Sun Chuanhui Chen Dr. Qinghua Zhang Christian Sohrt Tianqi Zhao Dr. Guanchen Xu Jinghui Wang Prof. Dong Wang Prof. Kai Rossnagel Prof. Lin Gu Prof. Chenggang Tao Prof. Liying Jiao 《Angewandte Chemie (International ed. in English)》2017,56(31):8981-8985
Two-dimensional (2D) metallic transition-metal dichalcogenides (TMDCs), such as 1T-TiSe2, have recently emerged as unique platforms for exploring their exciting properties of superconductivity and the charge density wave (CDW). 2D 1T-TiSe2 undergoes rapid oxidation under ambient conditions, significantly affecting its CDW phase-transition behavior. We comprehensively investigate the oxidation process of 2D TiSe2 by tracking the evolution of the chemical composition and atomic structure with various microscopic and spectroscopic techniques and reveal its unique selenium-assisting oxidation mechanism. Our findings facilitate a better understanding of the chemistry of ultrathin TMDCs crystals, introduce an effective method to passivate their surfaces with capping layers, and thus open a way to further explore the functionality of these materials toward devices. 相似文献
998.
In this paper,we design a novel three-order autonomous system.Numerical simulations reveal the complex chaotic behaviors of the system.By applying the undetermined coefficient method,we find a heteroclinic orbit in the system.As a result,the Si’lnikov criterion along with some other given conditions guarantees that the system has both Smale horseshoes and chaos of horseshoe type. 相似文献
999.
Jun‐Sheng Duan Randolph Rach Shi‐Ming Lin 《Mathematical Methods in the Applied Sciences》2013,36(13):1790-1804
We present a new approach to calculate analytic approximations of blow‐up solutions and their critical blow‐up times. Our approach applies the Adomian decomposition–Padé method to quickly and easily compute the critical blow‐up times, which comprises the Adomian decomposition method combined with the Padé approximants technique. We validate our new approach with a variety of numerical examples, including nonlinear ODEs, systems of nonlinear ODEs, and nonlinear PDEs. Furthermore, our new method is shown to be more convenient than prior art that relies on compound discretized algorithms. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
1000.