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951.
N-type semiconducting polymers are attractive for organic electronics, but desirable electron-deficient units for synthesizing such polymers are still lacking. As a cousin of rylene diimides such as naphthalene diimide (NDI) and perylene diimide (PDI), anthracene diimide (ADI) is a promising candidate; its polymers, however, have not been achieved yet because of synthetic challenges for its polymerizable monomers. Herein, we present ingenious synthesis of two dibromide ADI monomers with dibromination at differently symmetrical positions of the ADI core, which are further employed to construct ADI polymers. More interestingly, the two obtained ADI polymers possess the same main-chain and alkyl-chain structures but different backbone conformations owing to varied linking positions between repeating units. This feature enables their different optoelectronic properties and film-state packing behavior. The ADI polymers offer first examples of conjugated polymer conformational isomers and are highly promising as a new class of n-type semiconductors for various organic electronics applications.Two anthracene diimide (ADI) polymers with the backbone conformational isomerism, new members of aromatic diimide polymers family, have been synthesized as a class of highly promising n-type semiconductors for organic electronics. 相似文献
952.
The excessive production and deposition of amyloid-β (Aβ) is one of the most important etiologies of Alzheimer''s disease (AD). The interaction between Aβ and metal ions produces aberrant reactive oxygen species (ROS), which induce oxidative stress and accelerate the progression of AD. To reduce Aβ plaques and ROS to maintain their homeostasis is an emerging and ingenious strategy for effective treatment of AD. Herein, we report the rational design of multifunctional micelles (MPGLT) based on a polymer-grafted peptide to simultaneously clear Aβ and ROS for AD therapy. The MPGLT integrating three functional peptides as a ROS scavenger (tk-GSH), β-sheet breaker (LP) and an autophagy activator (TK) respectively, could capture and degrade Aβ. Meanwhile, the tk-GSH on the surface of MPGLT effectively scavenges the intracellular ROS. Consequently, MPGLT reduced the cytotoxicity of Aβ and ROS. In vivo animal studies using an AD mouse model further showed that MPGLT could transport across the blood–brain barrier for decreasing the Aβ plaque and eliminating ROS in vivo. This peptide micelle-based synergistic strategy may provide novel insight for AD therapy.Multifunctional micelles based on a peptide–polymer for simultaneously targeting Aβ degradation and ROS scavenging for AD therapy. 相似文献
953.
Fangling Lu Zengzhuan Yang Tao Wang Tianhao Wang Yuying Zhang Yong Yuan Aiwen Lei 《中国化学》2019,37(6):538-538
The inside cover picture shows an electrochemical oxidative Csp3‐H/S‐H activation with hydrogen evolution for the synthesis of tetrasubstituted olefins. This method features very high atom economy, besides hydrogen gas, under the base‐free, transition met‐al‐free, and oxidants‐free conditions, no other by‐products were generated. More details are discussed in the article by Lei et al. on page 547–551.
954.
Jian Wang Xing‐You Xu Lu‐De Lu Xu‐Jie Yang Wei‐Xing Ma Xiang‐Ning Cui 《Surface and interface analysis : SIA》2007,39(6):482-486
The streaming potential of supersaturated solution of binary carboxylic acids, which have even carbon atoms, was determined to characterize crystallization under different temperatures. The value of the streaming potential was related to the type and solubility of the acids and the starting temperature of crystallization, and was easily influenced by the pressure difference of the liquid or the rate of temperature decline. When the temperature was declined to the point where a crystal nucleus appeared, the streaming potential reached the minimum. Thereafter, as the temperature was sequentially lowered, some minicrystals grew, and the streaming potential presented an ascendant tendency. The higher the starting temperature of the acids saturated solution, the higher is the temperature corresponding to the streaming potential minimum. The less the carbon atoms in the acids and the greater the solubility of the acids are, the higher is the temperature of the streaming potential minimum. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
955.
以A lC l3.6H2O、Na2MoO4.2H2O、CoC l2.6H2O和2,2′-联吡啶为主要原料合成了Anderson-B-型多金属氧酸盐[Co(2,2-′b ipy)3]H[A l(OH)6(Mo6O18)].5H2O,进行了红外光谱、紫外光谱、差热分析和单晶结构测定。晶体学测定结果表明,化合物属于三斜晶系,Pī空间群,晶胞参数:a=1.216 0(2),b=1.221 5(2),c=1.780 0(4)nm,α=86.83(3)°,β=88.76(3)°,γ=89.82(3)°,V=2.639 4(9)nm3,Z=2,R1=0.079 4,wR2=0.176 6。化合物结构分析表明,在晶体学上,标题化合物分子是由1个[Co(2,2-′b ipy)3]2 配阳离子,1个H 离子,2个1/2[A l(OH)6(Mo6O18)]3-多阴离子和5个结晶水分子组成。多阴离子[A l(OH)6(Mo6-O18)]3-借助水分子和金属配离子通过超分子作用形成二维网状结构,网状结构之间又借助超分子作用形成三维无限伸展结构。差热分析表明,标题化合物的失重过程分为2步,多阴离子骨架破坏温度为547.5℃。 相似文献
956.
A general strategy is proposed to assign aliphatic side-chain resonances of large 13C,15N-labeled proteins without deuteration, using 4D 13C,15N-edited NOESY and MQ-(H)CCH-TOCSY experiments on the basis of prior assignments of backbone and 13Cbeta resonances. The strategy has been tested on a 214 residue protein (DdCAD-1) and applied to a chain-selectively 13C,15N-labeled hemoglobin (65 kDa). About 96 and 80% aliphatic side-chain spins in DdCAD-1 and hemoglobin have been assigned, respectively. The strategy proposed here will be very useful for the structure determination and dynamics characterization of large proteins by NMR. 相似文献
957.
Li Mingdong Deng Weiwei Fan Yousan Yang Jiyuan Liu Xiaolei 《Plasma Chemistry and Plasma Processing》2004,24(1):73-84
In order to prolong cathode lifetime of hollow electrode plasma generators, a method of impressed double magnetic fields with an alternating frequency is presented in this paper. The alternating frequency of the double magnetic fields is an important factor that influences the erosion rate on the area between the two coils' central planes. By analyzing the arc movement in the hollow cathode with a simplified theoretical model, the spiral curve shape of the radial arc and the relationship between the optimal alternating frequency and the intensity of magnetic fields are obtained. A photoelectric method is employed to measure the arc root rotation speed in the hollow cathode, and then the optimal alternating frequency is calculated as 319 Hz for the experimental conditions. The life testing with this alternating frequency showed that the cathode lifetime could be prolonged significantly. 相似文献
958.
CuO/活性炭和Fe2O3/活性炭催化还原NO 总被引:4,自引:0,他引:4
CuO/活性炭和Fe_2O_3/活性炭催化还原NO高志明,赵震,杨向光,吴越(中国科学院长春应用化学研究所长春130022)关键词活性炭,还原,NO,氧化铜,氧化铁目前,对固定源的NO处理是采用V2O5/TiO2作催化剂,NH3作还原剂的选择催化还原方... 相似文献
959.
960.
QIN Jun XIE Ming-Gui JIANG Qing ZHAO Hua-Ming Department of Chemistry Sichuan University Chengdu Sichuan ChinaLIU Sheng-Chong Analytical Testing Center Sichuan University Chengdu Sichuan ChinaTAO Chang-Yuan Department of Chemistry Chongqing University Chongqing Sichuan China 《中国化学》1995,13(1):1-9
In view of the nature of orderness in structure and the mesomorphism in property of liquid crystal, the function of which is further exploited by integrating it with the feature of crown ether. The monoarmed crown ether liquid crystals are successfully applied to the imitation of biomembrane transport. Binary component membrane composed of crown ether liquid crystal and PVC was first developed. Such a novel model of biomimetic membrane is capable of imitating ingeniously the thermocontrolling transport of biomembrane, thus the essential function of liquid crystal in membane transport is more fully exploited. It was suggested, consequently, that the molecules of the crown ether liquid crystal could assemble themselves to form ionic channels, as they exist in mesophase.Of still more significance is that the thermocontrolling transport of ions through the membrane is found to be operative selectively and the permeation of ion is under the direct influence of the thermal turmoil of the crown ether liquid cr 相似文献