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931.
Hui Li Xiao-Chuan Chai Jie Wang Jun Li Chen-Zhong Yao 《Phosphorus, sulfur, and silicon and the related elements》2020,195(9):747-755
AbstractIn this contribution, two diiron ethane-1,2-dithiolate complexes with one ethyldiphenylphosphine or dicyclohexylphenylphosphine ligand have been synthesized and characterized as mimics for the active site of [FeFe]-hydrogenases. Treatment of complex [Fe2(CO)6(μ-SCH2CH2S)] (1) with ethyldiphenylphosphine or dicyclohexylphenylphosphine and Me3NO · 2?H2O as decarbonylating agent gave complexes [Fe2(CO)5(Ph2PCH2CH3)(μ-SCH2CH2S)] (2) and [Fe2(CO)5{PhP(C6H11)2}(μ-SCH2CH2S)] (3) in 93% and 86% yields, respectively. Complexes 2 and 3 were characterized by elemental analysis, IR, and NMR spectroscopy. X-ray crystallographic studies confirmed the molecular structures of complexes 2 and 3, indicating that they contain a butterfly diiron ethane-1,2-dithiolate cluster with five terminal carbonyl ligands and an apically-coordinated phosphine ligand. Additionally, the electrochemical properties of these complexes were investigated by cyclic voltammetry, suggesting that they can be regarded as electrocatalysts for the reduction of protons to H2 in the presence of HOAc. A possible mechanism for the proton reduction was proposed. 相似文献
932.
Wonihl Cho Youngsoon Baek Young Chai Kim Masakazu Anpo 《Research on Chemical Intermediates》2002,28(4):343-357
The decomposition of natural gas over Pd-NiO/Al2O3 and Pt-Sn/Al2O3 is carried out in a microwave catalytic reaction at room temperature. The decomposition of methane is caused by collision by excitation of unstable electronic state. Measuring the flow rate and plasma power can provide kinetic data and indicate the mechanism. The conversion of C2 products increases from 47 to 63.7% in the microwave plasma catalytic reaction with electric field. Comparing the activities of catalysts, Pd-NiO/Al2O3 bimetallic catalyst is more active than Pt-Sn/Al2O3 catalyst because of modification of the surface of catalysts by carbon formation. The kinetic modeling of plasma of methane conversion seems related to the power of the electric discharge. It was also revealed that proper coking or polymeric carbon formation improves the catalytic activity; therefore, the conversion of methane may increase over Pd-Ni/Al2O3 catalyst in the plasma system. 相似文献
933.
Choi KH Lee EB Yoo CD Baek HJ Kang SW Shin KC Lee YJ Kim HA Jeon JH Kim CW Shin DM Kim IG Son YW 《Experimental & molecular medicine》2005,37(6):546-552
Filaggrin is expressed in the cornified layer of epidermis and known to be one of the antigenic targets in rheumatoid arthritis. Although the citrulline residue in filaggrin is thought to be an antigenic determinant recognized by autoantibodies, the diagnostic sensitivity of synthetic citrullinated peptide is variable. To investigate the implication of anti-filaggrin antibodies recognizing uncitrullinated filaggrin in rheumatoid arthritis, we assayed antibody titers using unmodified recombinant filaggrin in the sera from 73 patients with rheumatoid arthritis, 150 patients with other connective tissue diseases and 70 normal controls. We also performed the correlation analysis between antibody titers and the clinical variables in patients with rheumatoid arthritis. Titers of IgG anti-filaggrin antibodies were significantly higher in rheumatoid arthritis patients compared to normal controls (P=0.02), but not in patients with osteoarthritis, ankylosing spondylitis or systemic lupus erythematosus. IgG anti-filaggrin antibodies were more frequently found in patients with rheumatoid arthritis compared to normal controls (12.3% vs 1.4% respectively, P=0.04). An anti-filaggrin antibody titer was correlated with visual analogue scale of pain, tender joint count, Ritchie articular index or C-reactive protein, but not with anti-nuclear antibody or rheumatoid factor. These results suggest that anti-filaggrin antibody recognizes the uncitrullinated filaggrin as an antigen and its titer correlates with clinical parameters, explaining the variable sensitivity of anti-filaggrin antibody test. 相似文献
934.
为探索用电化学方法检测生物样品中氯霉素残留的高灵敏度技术,本实验研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)对氯霉素在玻碳电极上伏安行为的影响,实验结果表明,以0.02 mol/L高氯酸为支持电解质,在0.40~-0.60 V的范围内进行伏安扫描时,2×10-5mol/L CTMAB能显著提高氯霉素在-0.41 V处的还原峰电流。利用这种改进的电化学方法检测氯霉素的线性范围为0.0026~8 mg/L,检出限达到0.83μg/L。研究了缓冲液种类及其酸碱度及其它表面离子活性剂等对测试氯霉素的影响。 相似文献
935.
936.
Zhaofei Chai Qiong Wu Kai Cheng Xiaoli Liu Ling Jiang Maili Liu Conggang Li 《Chemical science》2021,12(3):1095
Thiols play critical roles in regulating biological functions and have wide applications in pharmaceutical and biomedical industries. However, we still lack a general approach for the simultaneous detection of various thiols, especially in complex systems. Herein, we establish a 19F NMR platform where thiols are selectively fused into a novelly designed fluorinated receptor that has two sets of environmentally different 19F atoms with fast kinetics (k2 = 0.73 mM−1 min−1), allowing us to generate unique two-dimensional codes for about 20 thiols. We demonstrate the feasibility of the approach by reliably quantifying thiol drug content in tablets, discriminating thiols in living cells, and for the first time monitoring the thiol related metabolism pathway at the atomic level. Moreover, the method can be easily extended to detect the activity of thiol related enzymes such as γ-glutamyl transpeptidase. We envision that the versatile platform will be a useful tool for detecting thiols and elucidating thiol-related processes in complex systems.A 19F NMR platform, capable of discriminating various small molecule thiols, was designed for in-cell thiol differentiation and monitoring, and further detection of the γ-GT activity, demonstrating the wide applications in thiol-related processes. 相似文献
937.
Soyoung Kim Bao-Ning Su Soedarsono Riswan Leonardus B.S. Kardono Johar J. Afriastini Judith C. Gallucci Heebyung Chai Norman R. Farnsworth Geoffrey A. Cordell Steven M. Swanson A. Douglas Kinghorn 《Tetrahedron letters》2005,46(52):9021-9024
Two benzo[b]oxepine derivatives, edulisones A (1) and B (2), were isolated from the bark of Aglaia edulis, collected in Indonesia. The relative stereochemistry of 1 was determined by single-crystal X-ray diffraction analysis. Treatment of compounds 1 and 2 with lithium hydroxide produced the same hydrolysis products, 1a and 1b, as a result of cleavage of the pyrrolidine ring to an alkylated amide mixture in each case, which demonstrated that these substances are epimeric at their 2-aminopyrrolidine moiety. 相似文献
938.
Chai Z Mao X Hu Z Zhang Z Chen C Feng W Hu S Ouyang H 《Analytical and bioanalytical chemistry》2002,372(3):407-411
Recent achievements in speciation studies of trace elements in the biological and environmental sciences by nuclear analytical techniques, mainly molecular activation analysis, position-sensitive spectrometry with a variety of exciting sources, and synchronous radiation-based analytical techniques (although radioisotope or enriched stable isotope-based speciation techniques are also used), particularly in our laboratory, are outlined. In this paper the merits and drawbacks of the nuclear analytical techniques are discussed, as are reagent blanks, contamination, and artifacts. 相似文献
939.
Determination of oleanolic acid and ursolic acid in cornel by cyclodextrin-modified micellar electrokinetic chromatography 总被引:2,自引:0,他引:2
A cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) method was established for the determination of oleanolic acid and ursolic acid in cornel. The two components were separated in the running buffer of 40 mmol/L sodium borate containing 5% methanol, 25 mmol/L SDS and 15 mmol/L hydroxypropyl-beta-cyclodextrin (HP-beta-CD). The applied voltage was 24 kV. The wavelength of detection was 200 nm. The temperature was kept at 25 C. Cinnamic acid was used as the internal standard. The analytical performance of the method was tested with respect to linearity, precision and recovery. The calibration curves were linear in the range of 10.15-243.6 microg/mL, r=0.9993 (oleanolic acid) and 10.07-241.7 microg/mL, r=0.9994 (ursolic acid); the intra-day precision (RSD) was less than 3.7% (oleanolic acid) and 4.1% (ursolic acid); the inter-day precision (RSD) was less than 4.2% (oleanolic acid) and 4.9% (ursolic acid). The limits of detection were 1.6 microg/mL for both components. The method proved to be sensitive, rapid, accurate and suitable for the determination of oleanolic acid and ursolic acid in cornel. 相似文献
940.
A novel bis-phenanthryl N-heterocyclic carbene (NHC) based palladium acetate catalyst was effective for the coupling of various aryl and vinyl chlorides with organoboron compounds. N,N-Bis-(2,9-dicyclohexyl-10-phenanthryl)-4,5-dihydroimidazolium chloride 8 (H2ICP·HCl) with Pd(OAc)2 and KF·18-c-6 in THF at room temperature gave Suzuki-Miyaura coupling of aryl and vinyl chorides, including unactivated and di-ortho substituted substrates in high yields. Hindered tri- and tetra-ortho substituted products were also efficiently produced. Benzyl chloride was also found to be a useful coupling partner and trimethylboroxine was used to give methylated products. The effect of ligand, base, temperature, solvent, and reaction time are reported along with various substrates including halides and triflates. 相似文献