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931.
The complexes of a cationic conjugated polymer with DNA are designed as new platforms for homogeneous, sensitive and facile fluorescence assays for SNP genotyping, which interface with single-base extension, multi-step FRET and optical amplification properties of conjugated polymers. 相似文献
932.
Liangshen Duan Qin Nie Yongxin Hu Liming Wang Kaiyan Guo Zhuoyi Zhou Xu Song Yuanhong Tu Hui Liu Thomas Hansen Jian-song Sun Qingju Zhang 《Angewandte Chemie (International ed. in English)》2023,62(33):e202306971
Herein, we described the first synthesis of the pentasaccharide and decasaccharide of the A. baumannii ATCC 17961 O-antigen for developing a synthetic carbohydrate-based vaccine against A. baumannii infection. The efficient synthesis of the rare sugar 2,3-diacetamido-glucuronate was achieved using our recently introduced organocatalytic glycosylation method. We found, for the first time, that long-range levulinoyl group participation via a hydrogen bond can result in a significantly improved β-selectivity in glycosylations. This solves the stereoselectivity problem of highly branched galactose acceptors. The proposed mechanism was supported by control experiments and DFT computations. Benefiting from the long-range levulinoyl group participation strategy, the pentasaccharide donor and acceptor were obtained via an efficient [2+1+2] one-pot glycosylation method and were used for the target decasaccharide synthesis. 相似文献
933.
Nan Zhang Ying Li Dr. Sanyang Han Dr. Ying Wei Huan Hu Ran Huo Dr. Chunbo Duan Dr. Jing Zhang Dr. Chunmiao Han Prof. Guohua Xie Prof. Hui Xu 《Angewandte Chemie (International ed. in English)》2023,62(27):e202305018
Clusters combine the advantages of organic molecules and inorganic nanomaterials, which are promising alternatives for optoelectronic applications. Nonetheless, recently emerged cluster light-emitting diodes require further excited state optimization of cluster emitters, especially to reduce population of the cluster-centered triplet quenching state (3CC). Here we report that redox-active ligands enhance reverse intersystem crossing (RISC) of Cu4I4 cluster for triplet-to-singlet conversion, and thermally activated delayed fluorescence (TADF) host can provide an external RISC channel. It indicates that the complementarity between TADF host and cluster in RISC transitions gives rise to 100 % triplet conversion efficiency and complete singlet exciton convergence, rendering 100-fold increased singlet radiation rate constant and tenfold decreased triplet non-radiation rate constant. We achieve a photoluminescence quantum yield of 99 % and a record external quantum efficiency of 29.4 %. 相似文献
934.
Yuan Q Yin AX Luo C Sun LD Zhang YW Duan WT Liu HC Yan CH 《Journal of the American Chemical Society》2008,130(11):3465-3472
The facile synthesis of highly ordered mesoporous aluminas with high thermal stability and tunable pore sizes is systematically investigated. The general synthesis strategy is based on a sol-gel process associated with nonionic block copolymer as templates in ethanol solvent. Small-angle XRD, TEM, and nitrogen adsorption and desorption results show that these mesoporous aluminas possess a highly ordered 2D hexagonal mesostructure, which is resistant to high temperature up to 1000 degrees C. Ordered mesoporous structures with tunable pore sizes are obtained with various precursors, different acids as pH adjustors, and different block copolymers as templates. These mesoporous aluminas have large surface areas (ca. 400 m2/g), pore volumes (ca. 0.70 cm3/g), and narrow pore-size distributions. The influence of the complexation ability of anions and hydro-carboxylic acid, acid volatility, and other important synthesis conditions are discussed in detail. Utilizing this simple strategy, we also obtained partly ordered mesoporous alumina with hydrous aluminum nitrate as the precursor. FTIR pyridine adsorption measurements indicate that a large amount of Lewis acid sites exist in these mesoporous aluminas. These materials are expected to be good candidates in catalysis due to the uniform pore structures, large surface areas, tunable pore sizes, and large amounts of surface Lewis acid sites. Loaded with ruthenium, the representative mesoporous alumina exhibits reactant size selectivity in hydrogenation of acetone, D-glucose, and D-(+)-cellobiose as a test reaction, indicating the potential applications in shape-selective catalysis. 相似文献
935.
A centrosymmetric compound consisting of neutral zigzag chains of [Co(C2O4)(HO(CH2)3OH)]n displays strong intrachain antiferromagnetic interaction and 3D weak ferromagnetic ordering at 10.6 K. 相似文献
936.
Yang Zheng Dr. Junhua Chen Chunguo Duan Xinyue Zhang Dr. Xuefang Xu Dr. Qian Gou 《Chemphyschem》2023,24(7):e202200804
The pure rotational spectra of 1-phenylethanol and its monohydrate were measured by using a pulsed jet Fourier transform microwave spectrometer. One conformer of the 1-phenylethanol monomer with the trans form was observed in the pulsed jet. The experimental values of rotational constants of ten isotopologues, including eight mono-substituted 13C and one D isotopologues, allow an accurate structure determination of the skeleton of 1-phenylethanol. For its monohydrate, only one isomer has been observed, of which 1-phenylethanol adopts the trans form and binds with water through an O−H⋅⋅⋅Ow and an Ow−H⋅⋅⋅π hydrogen bond. Each rotational transition displays a doublet with a relative intensity ratio of 1 : 3, due to a hindered internal rotation of water around its C2 axis. This study provides the information on accurate geometry of 1-phenylethanol (PE) and large amplitude motion of water in the PE monohydrate. 相似文献
937.
Zhao-Yu?WangEmail author Wen-Ying?Du Zhang-Qun?Duan Rong-Ling?Yang Yan-Hong?Bi Xiao-Tian?Yuan Yan-Yong?Mao Yu-Ping?Zhao Jie?Wu Jian-Bo?Jia 《Applied biochemistry and biotechnology》2016,179(6):1011-1022
Bio-based solvents have recently been discussed as sustainable green and promising alternatives to conventional organic media for enzymatic processes. In this paper, highly regioselective synthesis of the 6″-O-crotonyl-polydatin catalyzed by Thermomyces lanuginosus lipase (TLL) in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was successfully performed for the first time. The results indicated that TLL lipase displayed significantly improved catalytic performance in 2-MeTHF than in other traditional solvents. Under the optimal conditions, the initial reaction rate, 6″-regioselectivity, and maximum substrate conversion were as high as 12.38 mM h?1, 100 %, and 100 %, respectively. Moreover, further investigations on the operational stability, kinetic parameters like V max, K m, V max/K m, and E a revealed that 2-MeTHF exhibited excellent biocompatibility and rendered the greener process of the enzymatic acylation. 相似文献
938.
939.
Multiply robust inference has attracted much attention recently in the context of missing response data. An estimation procedure is multiply robust, if it can incorporate information from multiple candidate models, and meanwhile the resulting estimator is consistent as long as one of the candidate models is correctly specified. This property is appealing, since it provides the user a flexible modeling strategy with better protection against model misspecification. We explore this attractive property for the regression models with a binary covariate that is missing at random. We start from a reformulation of the celebrated augmented inverse probability weighted estimating equation, and based on this reformulation, we propose a novel combination of the least squares and empirical likelihood to separately handling each of the two types of multiple candidate models, one for the missing variable regression and the other for the missingness mechanism. Due to the separation, all the working models are fused concisely and effectively. The asymptotic normality of our estimator is established through the theory of estimating function with plugged-in nuisance parameter estimates. The finite-sample performance of our procedure is illustrated both through the simulation studies and the analysis of a dementia data collected by the national Alzheimer’s coordinating center. 相似文献
940.
Hierarchically Structured Porous Silica Spheres by Microemulsion/Vesicle Templating for Hydrodesulfurization of Fluid Catalytic Cracking Diesel 下载免费PDF全文
Xiaofeng Zhou Kebin Chi Aijun Duan Zhen Zhao Honghong Dong Yanjun Gong Shaotong Song Xilong Wang Chunming Xu 《Particle & Particle Systems Characterization》2016,33(4):190-203
A series of hierarchically structured porous silica sphere (HSPSS) materials are successfully fabricated by a facile, one‐step microemulsion/vesicle bimodal method in a multicomponent microemulsion system of P123/n‐butanol/1,3,5‐trimethylbenzene/KCl/H2O (surfactant/cosurfactant/oil/salt/water). The pore structures of the obtained HSPSS products consist of mesocellular foam and mesostructured vesicles. In contrast to the traditional porous silica materials the new structures combine two separate, distinct mesophases with different‐sized mesovoids in a single porous sphere. Moreover, the proportion of every mesophase in obtained HSPSS can be easily adjusted by tuning the initially added amount of n‐butanol or KCl in this multicomponent microemulsion system. When the molar ratio of KCl/tetraethoxysilane is 2.15, the obtained HSPSS material is turned into uniform mesostructured vesicle silica spheres, which consist of many small diameter vesicle particles. The hydrodesulfurization (HDS) activity of fluid catalytic cracking diesel over the HSPSS was tested. HSPSS‐0.75‐1.43 catalyst support with multiple mesoporous structures shows the highest HDS efficiency (98.5%) among all the studied catalysts. 相似文献