Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt% LaNi5复合储氢合金的电化学性能与协同效应

为了改善钛钒基固溶体合金的电化学性能,利用两步电弧熔炼法制备复合储氢合金Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt%LaNi5,X-射线衍射(XRD)和场发射扫描电镜-能谱(FESEM-EDS)显示:复合储氢合金的主相是体心立方结构的钒基固溶体相和六方结构的C14 Laves相,复合过程中生成了第二相。电化学测试结果表明:复合合金电极的P-C-T特征、活化性能、最大放电容量、循环稳定性、低温放电性能和动力学特性均较母体合金有显著改善。复合合金电极的活化周期数为5,最大放电容量为353.9 mAh.g-1,233 K时低温放电能力为50.26%。该复合合金电极的最大储氢容量、平台压、电荷转移电阻和交换电流密度均存在协同效应;在任意循环、在高/低温下以及在高倍率放电过程中,该复合合金电极的放电容量均存在协同效应。     

Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

A reaction ofα-bromo aromatic ketones in water with microwave irradiation gave the correspondingα-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis ofα-hydroxy aromatic ketones.     

High performance liquid chromatography with immobilized Ru(bpy)_3~(2+)-KMnO_4 chemiluminescence detection and its application in metabolism of repaglinide in pig liver microsomes

A novel high performance liquid chromatography-chemiluminescence（HPLC-CL） method for investigation of in vitro metabolism of repaglinide in pig liver microsomes with microdialysis sampling technique was developed.The chromatographic separation was performed on a Hypersil BDS-C18 column with an isocratic mobile phase consisting of methanol and 0.01 mol/L KH₂PO₄（pH 3.0）（volume ratio 75:25） at a flow rate of 1.0 mL/min.The detection was based on the chemiluminescence reaction of repaglinide with acidic potassium permanganate（KMnO₄） and tris（2,2’-bipyridyl）ruthenium（Ⅲ）(Ru（bpy）₃³⁺),which was immobilized on the cationic ion-exchange resin for obtaining high sensitivity and reducing consumption of expensive reagent.     

A theoretical investigation on the structures and stabilities of C<Subscript>60</Subscript>X<Subscript>18</Subscript> and C<Subscript>70</Subscript>X<Subscript>10</Subscript> (X = H,F, Cl,and Br)

A density functional theory study was performed on fullerene derivatives C₆₀X₁₈ and C₇₀X₁₀ (X = H, F, Cl, and Br). The calculated results show that the lowest energy isomers are IPR-satisfying for C₆₀X₁₈ (X = H, F, Cl, and Br). It is found that the addition patterns of X (X = Cl and Br) are different from those of X (X = H and F) for C₆₀, demonstrating that the stability of fullerene derivatives is partly attributed to the steric repulsion and electronegativity of added atoms. However, the lowest energy isomers are IPR-violating for C₇₀X₁₀ (X = H, F, and Cl), suggesting that many more fullerene derivatives may violate the isolated pentagon rule.     

Synchronous high-performance liquid chromatography with a photodiode array detector and mass spectrometry for the determination of citrinin, monascin, ankaflavin, and the lactone and acid forms of monacolin K in red mold rice

The Monascus fermentation product red mold rice (RMR) has been found to contain the cholesterol-lowering agent monacolin K (MK) in both its lactone (MKL) and acid (MKA) forms and the mycotoxin citrinin (CT). The yellow pigments in RMR, namely, monascin (MS) and ankaflavin (AK), have been reported to exhibit antimetastatic and antiangiogenic activities. Currently, MK and these yellow pigments are usually detected in RMR by different analytical methods that are inconvenient, expensive, and time-consuming. The goal of this study was to establish a rapid, synchronous analytical method for determination of the MKA, MKL, MS, AK, and CT levels in RMR. MKA, MKL, MS, AK, and CT were extracted by the same extraction method, then separated by RP-HPLC with a C18 column. The effluent from the column was passed through a photodiode array detector and then introduced directly into a fluorescence detector. The results showed that high recovery rates of MKA, MKL, MS, AK, and CT are possible if RMR powder is extracted with 75% ethanol (10 mL) at 80 degrees C for 30 min. With regard to the optimal conditions of the HPLC, the peaks of MKA, MKL, MS, AK, and CT can be clearly separated from any noise peaks by isocratic elution with a mobile phase comprising 0.05% trifluoroacetic acid in acetonitrile-water (62.5 + 37.5, v/v).     

Synergistic antibacterial and antibiotic effects of bisbenzylisoquinoline alkaloids on clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA)

The antibacterial activity of two bisbenzylisoquinoline alkaloids, tetrandrine (Tet) and demethyltetrandrine (d-Tet), alone and in combination with the antibiotics ampicillin (AMP), azithromycin (AZM), cefazolin (CFZ) and levofloxacin (LEV) against 10 clinical isolates of staphylococcal chromosomal cassette mec (SCCmec) III type methicillin-resistant Staphylococcus aureus (MRSA) was studied. Susceptibility to each agent alone was tested using a broth microdilution method. The chequerboard and time-kill tests were used for the combined evaluations. The minimal inhibitory concentrations/minimal bactericidal concentrations (MICs/MBCs, μg/mL) ranges alone were 64-128/256-1,024 for both Tet and d-Tet. Significant synergies against 90% of the isolates were observed for the Tet/CFZ combination, with their MICs being reduced by 75-94% [fractional inhibitory concentration indices (FICIs) ranged from 0.188 to 0.625], respectively. An additive bactericidal result was also observed for the Tet (d-Tet)/CFZ combination in the time-kill experiments. These results demonstrated that Tet and d-Tet enhanced the in vitro inhibitory efficacy of CFZ. Their potential for combinatory therapy of patients infected with MRSA warrants further pharmacological investigation.     

Ultra-sensitive microfibre absorption detection in a microfluidic chip

We report a microfibre absorption sensor by using a 900 nm diameter silica microfibre embedded in a 125 μm wide microchannel with a detection length of 2.5 cm. Investigated by measuring the absorbance of methylene blue (MB), the sensor shows a detection limit down to 50 pM with excellent reversibility in a concentration range of 0-5 nM. The sensor has also been applied to bovine serum albumin (BSA) measurement, with a detection limit of 10 fg mL(-1). In addition, the sample volume requirement is merely 500 nL with a probing light power of about 150 nW, which is very promising for safe detection of single or a few molecules of biological specimens.     

A local average connectivity-based method for identifying essential proteins from the network level

Identifying essential proteins is very important for understanding the minimal requirements of cellular survival and development. Fast growth in the amount of available protein-protein interactions has produced unprecedented opportunities for detecting protein essentiality from the network level. Essential proteins have been found to be more abundant among those highly connected proteins. However, there exist a number of highly connected proteins which are not essential. By analyzing these proteins, we find that few of their neighbors interact with each other. Thus, we propose a new local method, named LAC, to determine a protein's essentiality by evaluating the relationship between a protein and its neighbors. The performance of LAC is validated based on the yeast protein interaction networks obtained from two different databases: DIP and BioGRID. The experimental results of the two networks show that the number of essential proteins predicted by LAC clearly exceeds that explored by Degree Centrality (DC). More over, LAC is also compared with other seven measures of protein centrality (Neighborhood Component (DMNC), Betweenness Centrality (BC), Closeness Centrality (CC), Bottle Neck (BN), Information Centrality (IC), Eigenvector Centrality (EC), and Subgraph Centrality (SC)) in identifying essential proteins. The comparison results based on the validations of sensitivity, specificity, F-measure, positive predictive value, negative predictive value, and accuracy consistently show that LAC outweighs these seven previous methods.     

Ligand-free palladium-catalyzed intramolecular Heck reaction of secondary benzylic bromides

A facile ligand-free palladium-catalyzed intramolecular Heck reaction of β-hydrogen-containing secondary benzylic bromides was developed, which affords pyrroline derivatives with good regioselectivities.     

A facile process for the asymmetric synthesis of β-trifluoromethylated β-amino ketones via addition of ketone enolates to sulfinylimine

An efficient method for the asymmetric synthesis of β-trifluoromethylated β-amino ketones via addition of ketone-derivative enolates to trifluoromethylated sulfinylimine has been developed, with good chemical yields and excellent diastereoselectivities. This practical method was also proved to be suitable for large-scale preparation.