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991.
Yanhong Chao Wenshuai Zhu Jiaxin Chen Peiwen Wu Huaming Li 《Green Chemistry Letters and Reviews》2014,7(4):330-336
Graphene-like layered hexagonal boron nitride (g-BN) was prepared and characterized. The performance of using g-BN as an adsorbent for removal of fluoroquinolone antibiotic gatifloxacin (GTF) from aqueous solution was evaluated. g-BN showed an excellent adsorption capability with notable GTF adsorption ratio of more than 90%. Data of equilibrium adsorption of GTF onto g-BN at different temperatures were represented by Langmuir, Freundlich and Tempkin isotherm models, and Langmuir exhibited the best fitting with the maximum adsorption capacity of 88.5 mg·g?1 at 288 K. GTF adsorption was insignificantly affected by solution pH. Competitive role of Na+ and Ca2+ in the solution inhibited the adsorption of GTF and decreased the adsorption capacity a bit. The adsorption process was spontaneous and exothermic. The adsorption was probably governed by π–π interaction between GTF and g-BN, and electrostatic interaction may also exist in the adsorption process. 相似文献
992.
Jiang Zhao Meng Lian Yue Yu Xiaogang Yan Xianbin Xu Xiaolong Yang Guijiang Zhou Zhaoxin Wu 《Macromolecular rapid communications》2015,36(1):71-78
A series of novel red phosphorescent polymers is successfully developed through Suzuki cross‐coupling among ambipolar units, functionalized IrIII phosphorescent blocks, and fluorene‐based silane moieties. The photophysical and electrochemical investigations indicate not only highly efficient energy‐transfer from the organic segments to the phosphorescent units in the polymer backbone but also the ambipolar character of the copolymers. Benefiting from all these merits, the phosphorescent polymers can furnish organic light‐emitting diodes (OLEDs) with exceptional high electroluminescent (EL) efficiencies with a current efficiency (η L) of 8.31 cd A−1, external quantum efficiency (η ext) of 16.07%, and power efficiency (η P) of 2.95 lm W−1, representing the state‐of‐the‐art electroluminescent performances ever achieved by red phosphorescent polymers. This work here might represent a new pathway to design and synthesize highly efficient phosphorescent polymers.
993.
Sheng‐Yu Shi Ya‐Guang He Wei‐Wei Chen Na Liu Yuan‐Yuan Zhu Yun‐Sheng Ding Jun Yin Zong‐Quan Wu 《Macromolecular rapid communications》2015,36(16):1511-1520
Hybrid rod‐rod diblock copolymers, poly(γ‐benzyl L‐glutamate)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PBLG‐PPI), with determined chirality are facilely synthesized through sequential copolymerization of γ‐benzyl‐L‐glutamate N‐carboxyanhydride (BLG‐NCA) and phenyl isocyanide monomers bearing chiral menthyl pendants using a Ni(cod)(bpy) complex as the catalyst in one‐pot. Circular dichroism and absorption spectra reveal that each block of the block copolymers possesses a stable helical conformation with controlled helicity in solution due to the induction of chiral pendants. The two diastereomeric polymers self‐assemble into helical nanofibrils with opposite handedness due to the different chiral induction of the L‐ and D‐menthyl pendants, confirmed by transmission electron microscopy (TEM). Deprotection of the benzyl groups of the PBLG segment affords biocompatible amphiphilic diblock copolymers, poly(L‐glutamic acid)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PLGA‐PPI), that can self‐assemble into well‐defined micelles by cosolvent induced aggregation. Very interestingly, a chiral rhodamine chromophores RhB(D) can be selectively encapsulated into the chiral polymeric micelles, which is efficiently internalized into living cells when directly monitored with a confocal microscope. This contribution will be useful for developing novel rod‐rod biocompatible hybrid block copolymers with a controlled helicity, and may also provide unique chiral materials for potential bio‐medical applications.
994.
Juanzi Shi HongXia Shen Lisheng Zhang Peijie Wang Yan Fang Guozhen Wu 《Journal of Raman spectroscopy : JRS》2015,46(12):1303-1309
An algorithm is employed to retrieve the differential bond polarizabilities (DBP) of the C‐C bonds from the Raman optical activity spectrum of (‐)β‐pinene. (‐)β‐pinene possesses two stereo centers (chiral centers) and a local mirror reflection that interchanges the S type part and R type part in one molecular. It is demonstrated that this local mirror reflection could induce an approximate (or symmetry breaking) mirror reflection that reverses the signs of the DBP of the pair bond coordinates that are related to each other by the mirror reflection.This can be called intramolecular enantiomerism (IE). More cases of IE are discussed by the analysis of (‐)α‐pinene, (R)‐(+)‐4‐isopropyl‐1‐methylcyclohexene and (R)‐(+)‐3‐methylcyclohexanone together with previously studied limonene case. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
995.
Yiqi Zhang Zhenkun Wu Milivoj R. Beli Huaibin Zheng Zhiguo Wang Min Xiao Yanpeng Zhang 《Laser \u0026amp; Photonics Reviews》2015,9(3):331-338
The feasibility of realizing a photonic Floquet topological insulator (PFTI) in an atomic ensemble is demonstrated. The interference of three coupling fields will split energy levels periodically, to form a periodic refractive index structure with honeycomb profile that can be adjusted by different frequency detunings and intensities of the coupling fields. This in turn will affect the appearance of Dirac cones in momentum space. When the honeycomb lattice sites are helically ordered along the propagation direction, gaps open at Dirac points, and one obtains a PFTI in an atomic vapor. An obliquely incident beam will be able to move along the zigzag edge of the lattice without scattering energy into the PFTI, due to the confinement of edge states. The appearance of Dirac cones and the formation of a photonic Floquet topological insulator can be shut down by the third‐order nonlinear susceptibility and opened up by the fifth‐order one.
996.
Li Yang Fu Xuan Li Xu-Xin Zhang Fang Wu Qiang Wang Yun Yan Ze-Yi 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):877-888
Journal of Radioanalytical and Nuclear Chemistry - In this study, the imidazole-based poly(ionic liquid)s (PILs) synthesized by one step method has been applied for the enrichment and recovery of... 相似文献
997.
Chen Kuang Zhang Xiaojun Wang Fei Wu Yitian Zhou Haoxi Zhang Ying Zou Wenbo Zhang Jinming Liu Rong 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(7):2859-2868
Journal of Radioanalytical and Nuclear Chemistry - This study evaluated the potential of Al18F-labelled restrained complexing agent (RESCA)-ICG to assess hepatic function reserve on PET/CT imaging.... 相似文献
998.
CO2的有效利用有助于解决环境和生态问题.碳酸酐酶(CA)等酶分子可精准活化CO2分子以降低反应能垒,为CO2的高效和高选择性转化提供了一种有前景的途径.然而,酶离开生物体后易失活,且难以重复利用.目前,包埋型固定化酶是常用且有效的提高酶稳定性与回用率的方法之一,但载体的存在会造成反应物CO2内扩散阻力增加,降低反应活性.此外,CO2酶促转化是一个气-液-固三相反应过程,反应体系中CO2的外扩散性能也需要加强.金属有机骨架(MOFs),特别是咪唑酯骨架(ZIFs),常被用作酶固定化的载体.ZIFs的拓扑结构可被设计成不同形貌,进而通过ZIFs的结构工程来加强分子向其中的内扩散.Pickering乳液是指以固体颗粒代替常规表面活性剂而稳定的乳液.当固体颗粒具有催化活性时,催化剂颗粒会扩大液-液-固或气-液-固三相接触面积,从而有效协调反应物在不同相中的扩散时间.如果酶被用作这些颗粒的活性中心,所制备的Pickering乳液也可能具备类似的特性,可加强底物分子向酶的外扩散.本文选择两种具有不同结构的ZIFs(ZIF-L和ZIF-8),原位包埋CA后形成CA@ZIFs颗粒以稳定Pickeirng乳液.ZIF-L和CA@ZIF-L颗粒显示出独特的二维层状堆叠结构.ZIF-8和CA@ZIF-8颗粒呈棱角清晰的十二面体结构.与CA@ZIF-8颗粒相比,CA@ZIF-L颗粒显示出更大的孔径和更宽的孔径分布,这有助于CO2从CA@ZIF-L颗粒表面扩散至酶活性中心.利用酶活测试来研究内扩散是否通过结构工程得到了加强,发现CA@ZIF-L颗粒的活性比CA@ZIF-8颗粒高22.3%,推测这是由于CA@ZIF-L颗粒特殊的十字花状结构会缩短CO2从颗粒表面扩散至酶活性中心的距离.同时,十字花状结构可暴露更多的酶活性位点(CA@ZIF-L颗粒的暴露面积是CA@ZIF-8颗粒的~8倍),从而提升了反应物浓度并显示出更高的催化活性.本文还设计了吸附实验来进一步验证上述假设,发现BSA@ZIF-L颗粒对香豆素的吸附率远高于BSA@ZIF-8颗粒,说明与ZIF-8相比,酶包埋于ZIF-L具有更强的捕获小分子的能力,表明CO2分子向CA@ZIF-L的扩散速度更快,即CA@ZIF-L的十字花状结构可强化系统的内扩散过程.进一步比较了PIBS和游离多酶体系的催化活性,将CO2通入每个系统,在反应前20 min,PIBS的pH值下降速度比游离体系快得多,说明PIBS通过在气相和液相间构建更大的界面,缩短了CO2向CA的扩散距离,从而提高了催化效率,促进了CO2转化.上述假设也通过扩散动力学的计算得到了验证.为进一步研究PIBS的CO2矿化能力,本文开展了CaCO3矿化反应,发现PIBS的CaCO3产量远高于游离多酶体系,表明构建的PIBS在强化内外扩散方面具有显著优势.最后,评估了PIBS在工业应用中的性能,由CA@ZIF-L和CA@ZIF-8颗粒构建的PIBS显示出较好的可回收性,在第8个循环后,PIBS仍可保持8.9 mg/5 min的CaCO3产量.综上,PIBS可为CO2的酶促转化和框架提供一个新方法和新平台. 相似文献
999.
1000.
Chen C. Y. Kao C. L. Yeh H. C. Li H. T. Wu M. D. Cheng M. J. Li W. J. 《Chemistry of Natural Compounds》2022,58(3):385-386
Chemistry of Natural Compounds - A new ketone, vicamazone (4-(2-butoxyethoxy)-4-methylpentan-2-one) (1), was isolated from the leaves of Victoria amazonica (Nymphaeaceae). The structure of the new... 相似文献