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81.
Muhammad Waqas Ali Siyuan Cheng Jianhao Si Muhammad Siddiq Xiaodong Ye 《Journal of polymer science. Part A, Polymer chemistry》2019,57(19):2030-2037
Hyperbranched poly(2‐ethyl‐2‐oxazoline) was synthesized by a combination of cationic ring‐opening polymerization and the oxidation of thiol to disulfide groups. A three‐arm star poly(2‐ethyl‐2‐oxazoline) (PEtOx) was first synthesized using 1,3,5‐tris(bromomethyl) benzene as an initiator. The star PEtOx was end‐capped with potassium ethyl xanthate. Similarly, a linear PEtOx was synthesized and end‐capped with potassium ethyl xanthate using benzyl bromide as an initiator. Hyperbranched PEtOx was then obtained by in situ cleaving and subsequent oxidation of the star PEtOx and linear PEtOx mixture with n‐butylamine as both a cleaving agent and a base in tetrahydrofuran. The linear PEtOx was used to prevent the formation of gel. The hyperbranched PEtOx can be cleaved with dithiothreitol to trithiol and monothiol polymer. The hyperbranched PEtOx shows no remaining thiols using Ellman's assay. The resulting hyperbranched PEtOx was hydrolyzed to a novel hyperbranched polyethyleneimine with degradable disulfide linkages. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2030–2037 相似文献
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Samira Benmouloud Rachid Echarghaoui Si. Mohammed Sbaï 《Journal of Mathematical Analysis and Applications》2012,396(1):375-385
In this paper, by using the Lusternik–Schnirelmann category, we obtain a multiplicity result for a quasilinear elliptic system with both concave and convex nonlinearities and critical growth terms in bounded domains. 相似文献
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Inside Back Cover: Stepwise Assembly of MII7 Clusters Revealed by Mass Spectrometry,EXAFS, and Crystallography (Chem. Eur. J. 51/2016)
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86.
This study aims to reveal the laws of the relationship between fractional-order system and integer-order system. Meanwhile, delayed feedback control is introduced to control the fractional-order PMSG (permanent magnet synchronous generator) model of a wind turbine. First, the fractional-order mathematical model of PMSG is established. Next, numerical simulations under different system orders are given and the system dynamic behaviors are analyzed in detail. Then, the delayed feedback control method is introduced to control the fractional-order PMSG and the control results when different parameters vary are analyzed. Complex dynamics are presented and some interesting phenomena are discovered. It is found that the system order influences the dynamics of the system in many aspects such as chaos pattern, bifurcation behavior, period window, shape and size of strange attractor. The delayed time, feedback gain, feedback limitation, system order can obviously influence the control result except the initial state of the system. Moreover, the feedback limitation has a minimum to successfully control the system to stable states and the system order also has a maximum to do so. 相似文献
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文章以陆军远程火力打击体系为背景,在Do DAF1.5的基础上,运用2.0版本中新增的能力视角与服务视角视图模型,系统分析了远程火力打击体系的构建问题,建立相应的模型,并结合UPDM统一建模软件对体系结构进行设计和动态验证。 相似文献
89.
Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn for Wearable Monitor
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Xinqin Liao Qingliang Liao Xiaoqin Yan Qijie Liang Haonan Si Minghua Li Hualin Wu Shiyao Cao Yue Zhang 《Advanced functional materials》2015,25(16):2395-2401
Functional electrical devices have promising potentials in structural health monitoring system, human‐friendly wearable interactive system, smart robotics, and even future multifunctional intelligent room. Here, a low‐cost fabrication strategy to efficiently construct highly sensitive graphite‐based strain sensors by pencil‐trace drawn on flexible printing papers is reported. The strain sensors can be operated at only two batteries voltage of 3 V, and can be applied to variously monitoring microstructural changes and human motions with fast response/relaxation times of 110 ms, a high gauge factor (GF) of 536.6, and high stability >10 000 bending–unbending cycles. Through investigation of service behaviors of the sensors, it is found that the microcracks occur on the surface of the pencil‐trace and have a major influence on the functions of the strain sensors. These performances of the strain sensor attain and even surpass the properties of recent strain sensing devices with subtle design of materials and device architectures. The pen‐on‐paper (PoP) approach may further develop portable, environmentally friendly, and economical lab‐on‐paper applications and offer a valuable method to fabricate other multifunctional devices. 相似文献
90.
Abstract A two-stage process was developed for the living polymerization of isobutylene (IB) employing di-tert-alcohol initiators in conjunction with BCl3 coinitiator in the first or initiation stage, followed by TiCl4 coinitiator in the second or propagation stage; the process was shown to yield high molecular weight (up to M n 20,000), narrow molecular weight distribution (MWD) M w/M n = 1.1–1.2) di-tert-chlorine telechelic polyisobutylenes (tCl-PIB-Clt). The initiation stage involves the homogeneous solution living polymerization of IB induced by the di-tert-alcohol/BCl3 combination in the presence of an electron donor such as N,N-dimethylacetamide in CH3Cl solvent at ?80°C and proceeds up to M n < 5000; this is followed by the propagation stage in which TiCl4 and the bulk of IB plus a sufficient amount of n-C6H14 are added to the charge to bring the solvent composition to CH3Cl/n-C6H14 60/40 v/v and the living polymerization is continued until high M n product is obtained. This two-stage process was developed because 1) it employs very inexpensive chemicals; 2) di-tert-alcohol/BCl3 combinations initiate living IB polymerization in CH3Cl but the product after reaching M n ≤ 5000 precipitates out of the CH3Cl solution, and di-tert-alcohol/BCl4 combinations do not initiate IB polymerization; and 3) di-tert-alcohol/BCl3 systems do not initiate (or only very slowly) the living polymerization of IB in CH3Cl/n-C6H14 mixtures, whereas similar TiCl4-based systems do. The polymerization remains living during both stages although the propagating species and solvent polarity are profoundly altered. The livingness of the system has been analyzed by kinetic experiments and the structure of the tCl-PIB-Clt product by routine spectroscopic means. 相似文献