吡罗红为底物的辣根过氧化物酶催化荧光反应测定葡萄糖

吡罗红在辣根过氧化物酶催化下可被过氧化氢氧化而使其荧光猝灭。在pH 7.2中性介质中,稳态催化速率由酶和底物浓度决定,催化体系服从Michaelis-Menten方程,用Lineweaver-Burk作图法求得米氏常数、最大反应速度、催化常数分别为2.4×10~(-5)mol·L-1,2.5×10~(-6)mol·L-1s-1,75.8 s-1。在最佳反应条件下,荧光F0/F的猝灭程度与过氧化氢浓度在0-3.6×10~(-7)mol·L-1范围内成线性关系,检测限为6.3×10~(-9)mol·L-1;当与葡萄糖氧化酶联用时,可定量检测葡萄糖,线性关系为0-8.0×10~(-7)mol·L-1,检测限为3.4×10~(-8)mol·L-1。方法用于分析人血清中葡萄糖含量,分析结果与苯酚-4-氨基安替比林法基本一致。     

Photoactivity of titanium dioxide/carbon felt composites prepared with the assistance of supercritical carbon dioxide: Effects of calcination temperature and supercritical conditions

TiO2-coated carbon felt(TCF)composite catalysts have been prepared via a supercritical treatment of titanium tetraisopropoxide(TTIP)as the precursor.The physical properties of the catalysts were characterized by means of thermogravimetric and differential thermal analysis(TG–DTA),X-ray diffraction(XRD),fluorescence spectroscopy,scanning electron microscopy (SEM),and BET surface areas techniques.The photocatalytic activities of the materials were evaluated using the degradation of Congo red(CR)as a probe rea...     

Prediction of protein structural class using novel evolutionary collocation-based sequence representation

Knowledge of structural classes is useful in understanding of folding patterns in proteins. Although existing structural class prediction methods applied virtually all state-of-the-art classifiers, many of them use a relatively simple protein sequence representation that often includes amino acid (AA) composition. To this end, we propose a novel sequence representation that incorporates evolutionary information encoded using PSI-BLAST profile-based collocation of AA pairs. We used six benchmark datasets and five representative classifiers to quantify and compare the quality of the structural class prediction with the proposed representation. The best, classifier support vector machine achieved 61-96% accuracy on the six datasets. These predictions were comprehensively compared with a wide range of recently proposed methods for prediction of structural classes. Our comprehensive comparison shows superiority of the proposed representation, which results in error rate reductions that range between 14% and 26% when compared with predictions of the best-performing, previously published classifiers on the considered datasets. The study also shows that, for the benchmark dataset that includes sequences characterized by low identity (i.e., 25%, 30%, and 40%), the prediction accuracies are 20-35% lower than for the other three datasets that include sequences with a higher degree of similarity. In conclusion, the proposed representation is shown to substantially improve the accuracy of the structural class prediction. A web server that implements the presented prediction method is freely available at http://biomine.ece.ualberta.ca/Structural_Class/SCEC.html.     

含1,4-二酮吡咯并吡咯和铂的共轭聚合物的场效应性质研究

本文介绍了一种含有1,4-二酮吡咯并吡咯和铂的金属有机共轭聚合物。通过紫外-可见吸收光谱及电化学测得该聚合物的LUMO和HOMO分别为-3.4e V和-5.3e V。通过旋涂方法制备了该材料的底栅底接触场效应器件,并在退火至160℃之后测得其最高性能为:空穴迁移率1.0×10-3cm2·V-1·s-1,开关比105,阈值电压-15V。同时,通过原子力显微镜和X射线衍射对材料薄膜的退火过程进行了研究。     

钴(Ⅱ)Schiff碱螯合物及其氧加合物的合成与表征

合成了一种新的四齿Schiff碱配体N,N-亚乙基-双(1-乙酰萘酚-2(L²),两种新的钴(Ⅱ)螯合物CoL²和CoL³·H₂O(L³=N,N-亚苯基(1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5)及两种新的1:1氧加合物CoL¹·Py·O₂·2H₂O(L¹=N,N-亚乙基-双(1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5)和CoL²·Py·O₂·2H₂O。用元素分析、IR、UV、ESR、¹HNMR、MS、TGA、磁矩和电导测定进行了表征。     

大孔吸附树脂分离纯化杜仲中活性成分

比较了AB-8．NKA-9．NKA-11．D-140．D-101．HPD-600、S-8及聚酰胺等8种吸附树脂对杜仲中的活性成分京尼平甙和松脂醇二葡萄糖甙的吸附及脱附性能．在静态吸附研究的基础上，筛选出效果较好的树脂进行动态实验研究．实验表明：最佳的同时分离纯化松脂醇二葡萄糖甙和京尼平甙的树脂为S-8．并进行了该树脂对杜仲中两种活性成分的吸附和脱附研究，确定了最佳的工艺参数。     

茚三酮缩硫苄基氨基硫脲金属螯合物的合成

用水合茚三酮与硫苄基氨基硫脲缩合成茚三酮缩硫苄基氨基硫脲,然后与相应的金属盐反应,合成了 Fe(Ⅰ),Co(Ⅱ),Cu(Ⅰ)和 Ni(Ⅱ)四种金属螯合物.用元素分析、IR、hNMRR,MS,DTG-TGA,电导和电子光谱进行了表征,确定组成为 ML·■H_2O 的螯合物(x=1或2).     

Banach空间同构于Hilbert空间的两个特征

引言令X,Y均为Banach空间,对于T∈П_p(X,Y)由闭图象定理存在c>0,使得 {sum from n=1 to∞||TX_n||~p}~(1/p)≤C||{X_n}_(n=1)~∞||_p~(?) A{X_a}_n=1~∞∈sl_p(X) 令π_(?)(T)=infc,称π,(T)为T的p—可和范数。由定义有||T||≤π_p(T). T为p—可和算子的另一个等价的定义是:如果存在c>0,使得对任意有限个元素X_1,…,X_a∈X,有     

Analysis and prediction of RNA-binding residues using sequence, evolutionary conservation, and predicted secondary structure and solvent accessibility

Identification and prediction of RNA-binding residues (RBRs) provides valuable insights into the mechanisms of protein-RNA interactions. We analyzed the contributions of a wide range of factors including amino acid sequence, evolutionary conservation, secondary structure and solvent accessibility, to the prediction/characterization of RBRs. Five feature sets were designed and feature selection was performed to find and investigate relevant features. We demonstrate that (1) interactions with positively charged amino acids Arg and Lys are preferred by the egatively charged nucleotides; (2) Gly provides flexibility for the RNA binding sites; (3) Glu with negatively charged side chain and several hydrophobic residues such as Leu, Val, Ala and Phe are disfavored in the RNA-binding sites; (4) coil residues, especially in long segments, are more flexible (than other secondary structures) and more likely to interact with RNA; (5) helical residues are more rigid and consequently they are less likely to bind RNA; and (6) residues partially exposed to the solvent are more likely to form RNA-binding sites. We introduce a novel sequence-based predictor of RBRs, RBRpred, which utilizes the selected features. RBRpred is comprehensively tested on three datasets with varied atom distance cutoffs by performing both five-fold cross validation and jackknife tests and achieves Matthew's correlation coefficient (MCC) of 0.51, 0.48 and 0.42, respectively. The quality is comparable to or better than that for state-of-the-art predictors that apply the distancebased cutoff definition. We show that the most important factor for RBRs prediction is evolutionary conservation, followed by the amino acid sequence, predicted secondary structure and predicted solvent accessibility. We also investigate the impact of using native vs. predicted secondary structure and solvent accessibility. The predictions are sufficient for the RBR prediction and the knowledge of the actual solvent accessibility helps in predictions for lower distance cutoffs.     

INTEGRAL BOUNDARY VALUE PROBLEM FOR FIRST ORDER IMPULSIVE INTEGRO-DIFFERENTIAL EQUATIONS

By developing a comparison result and using the monotone iterative technique, we obtain the existence of the minimal and the maximal solutions to an integral boundary value problem for first order impulsive integro-differential equations.