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971.
Two new compounds, 19-hydroxy-melodinine K (1) and melodiside (2), and 25 known compounds were isolated from leaves and twigs of Melodinus suaveolens. Their structures were elucidated based on 1- and 2-D NMR, FTIR, UV and MS spectroscopic data. 19-hydroxy-melodinine K showed cytotoxic activity against MDA-MB-231 breast, BCG-823 gastric, SW480 colon and Hela cancer cells. 相似文献
972.
Preparation of core–shell structure Fe3O4@SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His‐tag protein purification
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Qian Ni Bing Chen Shaohua Dong Lei Tian Quan Bai 《Biomedical chromatography : BMC》2016,30(4):566-573
The core–shell structure Fe3O4/SiO2 magnetic microspheres were prepared by a sol–gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu2+, Ni2+ and Zn2+, were chelated on the Fe3O4@SiO2–IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni2+‐chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe3O4@SiO2–IDA–Ni2+ magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His‐tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
973.
Recently, Panyushev(2015) raised five conjectures concerning the structure of certain root posets arising from Z-gradings of simple Lie algebras. This paper aims to provide proofs for four of them. Our study also links these posets with Kostant-Macdonald identity, minuscule representations, Stembridge's "t =-1 phenomenon", and the cyclic sieving phenomenon due to Reiner et al.(2004). 相似文献
974.
975.
976.
Yao Chen Wenchuan Wang Dong Xie Lili Wu Chaocan Zhang 《Journal of polymer science. Part A, Polymer chemistry》2021,59(14):1528-1539
TPPAlCl-PPN+Cl− binary catalyst (where TPPAlCl is 5,10,15,20-tetraphenylporphyrin aluminum chloride, PPN+Cl− is bis[triphenylphosphine] iminium chloride, the molar ratio of TPPAlCl to PPN+Cl− is 1 to 0.5) can initiate the effective one-pot/one-step ternary copolymerization of CO2, lactide and 4-vinyl-1-cyclohexene-1,2-epoxide, and the quaternary copolymerization of CO2, propylene oxide, lactide, 4-vinyl-1-cyclohexene-1,2-epoxide, to form multiblock poly(carbonate-co-lactide) products with pendant vinyl group. The ternary copolymerization product composes of polylactide (PLA) block and poy(vinylcyclohexylene carbonate) (PVCHC) block, and the quaternary copolymerization product composes of poy(propylene carbonate) (PPC) block, PLA block and PVCHC block, which are verified by 1H NMR, 13C NMR, 1H-1H cosy, hetero-nuclear multiple bond correlation, DTG, and Gel permeation chromatography analysis. The functionality and glass-transition temperature of the products can be easily adjusted by the copolymerization variables, such as the molar ratio of comonomers, copolymerization temperature, pressure of CO2, the concentration of the catalyst. 相似文献
977.
Lipases and esterases are important catalysts with wide varieties of industrial applications. Although many methods have been established for detecting their activities, a simple and sensitive approach for picogram detection of lipolytic enzyme quantity is still highly desirable. Here we report a lipase detection assay which is 1000-fold more sensitive than previously reported methods. Our assay enables the detection of as low as 5 pg and 180 pg of lipolytic activity by direct spotting and zymography, respectively. Furthermore, we demonstrated that the detection sensitivity was adjustable by varying the buffering capacity, which allows for screening of both high and low abundance lipolytic enzymes. Coupled with liquid chromatography-mass spectrometry, our method provides a useful tool for sensitive detection and identification of lipolytic enzymes. 相似文献
978.
Xiang Lai Yu Han Jie Zhang Jinyu Zhang Weifeng Lin Zhiwei Liu Longgang Wang 《Molecules (Basel, Switzerland)》2021,26(9)
The sensitive and selective detection of dopamine (DA) is very important for the early diagnosis of DA-related diseases. In this study, we reported the colorimetric detection of DA using Ganoderma lucidum polysaccharide (GLP) stabilized platinum nanoclusters (Ptn-GLP NCs). When Pt600-GLP NCs was added, 3,3’,5,5’-tetramethylbenzidine (TMB) was rapidly catalyzed and oxidized to blue oxTMB, indicating the peroxidase-like activity of Pt600-GLP NCs. The catalytic reaction on the substrate TMB followed the Michaelis-Menton kinetics with the ping-pong mechanism. The mechanism of the colorimetric reaction was mainly due to the formation of hydroxyl radical (•OH). Furthermore, the catalytic reaction of Pt600-GLP NCs was used in the colorimetric detection of DA. The linear range for DA was 1–100 μM and the detection limit was 0.66 μM. The sensitive detection of DA using Pt-GLP NCs with peroxidase-like activity offers a simple and practical method that may have great potential applications in the biotechnology field. 相似文献
979.
Dr. Naixia Lv Jie Yin Wendi Fu Jinrui Zhang Yujun Li Dr. Ding Jiang Dr. Hongping Li Prof. Wenshuai Zhu 《Chemphyschem》2021,22(2):168-177
The rational design of highly active hexagonal boron nitride (h-BN) catalysts at the atomic level is urgent for aerobic reactions. Herein, a doping impurity atom strategy is adopted to increase its catalytic activities. A series of doping systems involving O, C impurities and B, N antisites are constructed and their catalytic activities for molecular O2 have been studied by density functional theory (DFT) calculations. It is demonstrated that O2 is highly activated on ON and BN defects, and moderately activated on CB and CN defects, however, it is not stable on NB and OB defects. The subsequent application in oxidative desulfurization (ODS) reactions proves the ON and C-doped (CB, CN) systems to be good choice for sulfocompounds oxidization, especially for dibenzothiophene (DBT). While the BN antisite is not suitable for such aerobic reaction due to the extremely stable B−O*−B species formed during the oxidation process. 相似文献
980.
Mary Marshall Zhaoguo Zhu Rachel Harris Prof. Dr. Kit H. Bowen Wei Wang Jie Wang Chu Gong Prof. Dr. Xinxing Zhang 《Chemphyschem》2021,22(1):5-8
Thorium and its compounds have been widely investigated as important nuclear materials. Previous research focused on the potential use of thorium hydrides, such as ThH2, ThH4, and Th4H15, as nuclear fuels. Here, we report studies of the anion, ThH5−, by anion photoelectron spectroscopy and computations. The resulting experimental and theoretical vertical detachment energies (VDE) for ThH5− are 4.09 eV and 4.11 eV, respectively. These values and the agreement between theory and experiment facilitated the characterization of the structure of the ThH5− anion and showed its neutral counterpart, ThH5 to be a superhalogen. ThH5−, which exhibits a C4v structure with five Th−H single bonds, possesses the largest known H/M ratio among the actinide elements, M. The adaptive natural density partitioning (AdNDP) method was used to further analyze the chemical bonding of ThH5− and to confirm the existence of five Th−H single bonds in the ThH5− molecular anion. 相似文献