The facile synthetic method of 5-hydroxymethyluracil

One practical and industrial procedure for preparation of 5-hydroxymethyluracil has been developed. This method has the advantage of facile operation, low cost and stable yield.     

g factors of nuclear low-lying states:A covariant description

The g factors and spectroscopic quadrupole moments of low-lying excited states 2+1,…,81+ in 24Mg are studied in a covariant density functional theory.The wave functions are constructed by configuration mixing of axially deformed mean-field states projected on good angular momentum.The mean-field states are obtained from the constraint relativistic point-coupling model plus BCS calculations using the PC-F1 parametrization for the particle-hole channel and a density-independent delta-force for the particle-pa...     

Ionic Polyimide Derived Porous Carbon Nanosheets as High-Efficiency Oxygen Reduction Catalysts for Zn–Air Batteries

Two-dimensional (2D) porous carbon nanosheets (2DPCs) have attracted great attention for their good porosity and long-distance conductivity. Factors such as templates, precursors, and carbonization–activation methods, directly determine their performance. However, rational design and preparation of porous carbon materials with controlled 2D morphology and heteroatom dopants remains a challenge. Therefore, an ionic polyimide with both sp²- and sp³-hybridized nitrogen atoms was prepared as a precursor for fabricating N-doped hexagonal porous carbon nanosheets through a hard-template approach. Because of the large surface area and efficient charge-mass transport, the resulting activated 2D porous carbon nanosheets (2DPCs-a) displayed promising electrocatalytic properties for oxygen reduction reaction (ORR) in alkaline and acidic media, such as ultralow half-wave potential (0.83 vs. 0.84 V of Pt/C) and superior limiting current density (5.42 vs. 5.14 mA cm⁻² of Pt/C). As air cathodes in Zn–air batteries, the as-developed 2DPCs-a exhibited long stability and high capacity (up to 614 mA h g⁻¹), which are both higher than those of commercial Pt/C. This work provides a convenient method for controllable and scalable 2DPCs fabrication as well as new opportunities to develop high-efficiency electrocatalysts for ORR and Zn–air batteries.     

A theoretical study of the influence of dopants on the dehydrogenation properties of VH_2

Using the plane wave ultrasoft pseudopotential method based on the first-principles density functional theory(DFT),the influence on the electronic structure and dehydrogenation properties of VH2 doped with Zr,Cu and Zn has been studied.The results show that the negative heat of formation increases and the valence electron number at the Fermi level EF,N(EF) decreases in the Zr-doped model,indicating the higher stability of VH2 after Zr alloying.On the other hand,the negative heat of formation of VH2 decrease...     

A new quantitative structure-retention relationship model for predicting chromatographic retention time of oligonucleotides

An integrated approach is proposed to predict the chromatographic retention time of oligonucleotides based on quantitative structure-retention relationships(QSRR) models.First,the primary base sequences of oligonucleotides are translated into vectors based on scores of generalized base properties(SGBP),involving physicochemical,quantum chemical,topological,spatial structural properties,etc.;thereafter,the sequence data are transformed into a uniform matrix by auto cross covariance(ACC).ACC accounts for the ...     

多金属氧化物立方纳米晶体的可控合成及其与朊蛋白的特异性相互作用

研究表明,在有机小分子二甲基甲酰胺（DMF）的调控作用下Keggin型多金属氧化物在水溶液中形成规则的纳米立方体,随温度改变该纳米立方体转变为空心立方结构．该多金属氧化物纳米立方体可以与朊蛋白（PrP^c）相互作用,产生显著的光散射信号增强,且增强程度在3．36-840ng·mL^-1范围内与朊蛋白浓度呈线性关系．     

Synthesis and in vitro antibacterial activities of 7-(3-aminopyrrolo[3,4-c]pyrazol-5(2H,4H,6H)-yl)quinolone derivatives

<正>A series of novel 7-(3-aminopyrrolo[3,4-c]pyrazol-5(2H,4H,6H)-y1)quinolone derivatives were designed,synthesized and evaluated for in vitro antibacterial activities.Compounds 6g,7g and 7h with the potencies similar to those of gemifloxacin, moxifloxacin,gatifloxacin and levofloxacin against Gram-positive organisms,worth further investigation.     

氨基酸广义信息因子分析标度组合支持向量机模型用于β-turns预测及特征分析

提出一种新的组合方法用于β-turns预测和特征分析.该方法包括两步:如何表征β-turns特征和如何构建其预测模型.第一步应用氨基酸广义信息因子分析标度表征蛋白质中β-turns的结构特征,该标度涉及氨基酸的疏水性、α-螺旋与转角倾向、体积性质、构成特征、局部柔性及静电性.第二步以426个蛋白质为训练集样本,通过留1/7法交互验证,基于支持向量机建立β-turns预测模型.该模型分别成功地预测547和823个蛋白的β-turns.所得结果与所对比方法结果相当,更重要的是,SVM模型提供了一些关于β-turns特征的重要结构信息.该组合方法可以进一步尝试用于蛋白质结构预测及特征分析.     

Homochiral expression of proteins:a discussion on the natural chirality related to the origin of life

Homochirality in life has always been a driving force in scientific research and natural exploration. It has not been satisfactorily explained, and systematic investigations are necessary. This paper reported a homochiral expression of proteins dependent on the stirring direction of growing media. By controlling the stirring direction clockwise (CW) and anticlockwise (ACW) of the culture medium, proteins with distinct secondary structures were obtained, and D-amino acid may be included in the protein cultur...     

Using factor analysis scales of generalized amino acid information for prediction and characteristic analysis of β-turns in proteins based on a support vector machine model

This paper offers a new combined approach to predict and characterize β-turns in proteins.The approach includes two key steps,i.e.,how to represent the features of β-turns and how to develop a predictor.The first step is to use factor analysis scales of generalized amino acid information(FASGAI),involving hydrophobicity,alpha and turn propensities,bulky properties,compositional characteristics,local flexibility and electronic properties,to represent the features of β-turns in proteins.The second step is to ...