基于曲线拟合的形态相似鹅膏菌的傅里叶变换红外光谱研究

利用傅里叶变换红外光谱仪测试了形态相似的灰疣鹅膏菌、灰绒鹅膏菌和灰褶鹅膏菌的光谱,结果显示,它们的傅里叶变换红外光谱主要由蛋白质和多糖的振动吸收带组成,其蛋白质的吸收频率略有差。选择酰胺I带(中心频率1647cm-1)进行傅里叶自去卷积和曲线拟合处理后3种鹅膏菌中蛋白质在酰胺I带的吸收峰都由12个子峰叠加而成,其中在无序(1650cm-1)、α螺旋(1658cm-1)和β转角结构(1666cm-1)的振动吸收峰上,灰褶鹅膏菌吸收峰的面积百分比分别是20.98%、4.47%和17.14%,明显地区别于其它两种鹅膏菌(灰疣鹅膏菌:10.26%、12.58%和7.71%;灰绒鹅膏菌:14.33%、9.76%和8.83%)。在1683cm-1处的β转角吸收峰上,灰绒鹅膏菌吸收峰的面积百分比是1.92%,明显小于其它两种鹅膏菌(灰疣鹅膏菌:8.03%;灰褶鹅膏菌:6.65%)。研究表明:傅里叶变换红外光谱技术能提供大型真菌所含蛋白质二级结构信息。     

A mechanistic study of flame retardance of novel copolyester phosphorus containing linked pendant groups by TG/XPS/direct Py-MS

The flame retardant mechanism of the copolyester phosphorus containing linked pendant groups was investigated by thermogravimetric （TG）, X-ray photoelectron spectroscopy （XPS） and direct insertion probe pyrolysis mass spectrometry （DP-MS） technique. TG results show that the incorporation of phosphorus containing unit linked pendant groups can destabilize the copolyester due to the cleavage of P-CH2 bond, and phosphorus containing units cannot promote the char-formation of the copolyester during the thermal degradation of the copolyester. XPS spectra indicate that with the increase of the temperature, the P-CH2 bonds of the copolyester break down gradually, the concentration of phosphorus in the condensed phase products decrease gradually and the chemical state of phosphorus does not change in the temperature of 250-380 ℃. Direct pyrolysis MS suggests that the P-CH2 bonds cleavage occurs at pendant groups and species containing phosphorus can volatilize into the gas phase. A flame retardant mechanism is proposed for the gas phase mode of action of the halogen-free copolyester phosphorus containing linked pendant groups.     

Novel Flower‐Like Ag‐SiO2‐MgO‐Al2O3 Material: Preparation,Characterization and Catalytic Application in Methanol Dehydrogenation

Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag‐SiO₂‐MgO‐Al₂O₃ catalysts prepared by sol‐gel method. The optimal preparation mass fractions were determined as 8.3% MgO, 16.5% Al₂O₃ and 20% silver loading. Using this optimum catalyst, excellent activity and selectivity were obtained. The conversion of methanol and the selectivity to formaldehyde both reached 100%, which were much higher than other previously reported silver supported catalysts. Based on combined characterizations, such as X‐ray diffraction (XRD), scanning electronic microscopy (SEM), diffuse reflectance ultraviolet‐visible spectroscopy (UV‐Vis, DRS), nitrogen adsorption at low temperature, temperature programmed desorption of ammonia (NH₃‐TPD), desorption of CO₂ (CO₂‐TPD), etc., the correlation of the catalytic performance to the structural properties of the Ag‐SiO₂‐ MgO‐Al₂O₃ catalyst was discussed in detail. This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side‐products is attributed to its unique flower‐like structure with a surface area less than 1 m²/g, and the strong interactions between neutralized support and the nano‐sized Ag particles as active centers.     

Photoluminescence and Electroluminescence of Organic Light Emitting Diodes Based on Tris‐(8‐quinolinolato) Aluminum Nanoparticles

利用共沉淀方法制备出平均粒径为20nm的有机物8-羟基喹啉铝纳米粒子,8-羟基喹啉铝纳米粒子呈球形且粒度不随老化时间的增加而改变。本文研究了8-羟基喹啉铝纳米粒子的光致发光及基于8-羟基喹啉铝纳米粒子制作的电致发光器件的电致发光特性。8-羟基喹啉铝形成纳米粒子后,其光致发光及电致发光发射光谱的谱峰均出现蓝移。随着驱动电压的增加,器件中8-羟基喹啉铝纳米粒子的发射峰逐渐红移。在驱动电压为16伏时,8-羟基喹啉铝纳米粒子器件的最大亮度达600cd/m²,电流密度为150mA/cm^-2时,器件的发光效率为0.19cd/A。基于8-羟基喹啉铝纳米粒子器件的发射光谱证实了AlQ₃纳米粒子具有量子尺寸效应的存在,这为有机纳米电致发光器件的研究开辟了一条新的研究路线,同时也为那些传统的有机材料如有机分子晶体的基础研究探索出新的研究方向。     

Experimental and Theoretical Studies on DNA‐Binding and Spectral Properties of ‘Light Switch’ Complexes [Ru(L)2(ppn)]2+ (L=2,2′‐Bipyridine and 1,10‐Phenanthroline; ppn=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine)

The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its Ru^II complexes [Ru(bpy)₂(ppn)]²⁺ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)₂(ppn)]²⁺ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, ¹H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants K_b of (1.7±0.4)?10⁶ M ^?1 and (2.6±0.2)?10⁶ M ^?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)₂(ppn)]²⁺( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method.     

First principle MD study on the structural and electronic properties of liquid and amorphous NI81B19 and NI80P20 alloy

Atomic and electronic structures of liquid and amorphous Ni₈₁B₁₉ and Ni₈₀P₂₀ alloys were simulated by ab initio molecular dynamics. Pair correlation function, bond pair analysis, electronic population analysis, and density of states were calculated. It was found that amorphous Ni₈₁B₁₉ and Ni₈₀P₂₀ alloys can be prepared by rapid quenching, and their structures are similar to those of liquid alloys. Bond pair analysis indicated that the environment of each atom in Ni₈₁B₁₉ system is dominated by icosahedral and distorted icosahedral inherent structures; however, in Ni₈₀P₂₀ system, the tetrahedral order is preponderant. Strong interactions occur between the d‐electrons of Ni and the p‐electrons of B (or P), which leads to the covalent interactions between Ni and B (or P) atoms. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Structural Revisions of a Class of Natural Products: Scaffolds of Aglycon Analogues of Fusicoccins and Cotylenins Isolated from Fungi

The reisolation and structural revision of brassicicene D is described, and inspired us to reassign the core skeletons of brassicicenes C–H, J and K, ranging from dicyclopenta[a,d]cyclooctane to tricyclo[9.2.1.0^3,7]tetradecane using quantum‐chemical predictions and experimental validation strategies. Three novel, highly modified fusicoccanes, brassicicenes L–N, were also isolated from the fungus Alternaria brassicicola, and their structures were unequivocally established by spectroscopic data, ECD calculations, and crystallography. The reassigned structures represent the first class of bridgehead double‐bond‐containing natural products with a bicyclo[6.2.1]undecane carbon skeleton. Furthermore, their stabilities were first predicted with olefin strain energy calculations. Collectively, these findings extend our view of the application of computational predictions and biosynthetic logic‐based structure elucidation to address problems related to the structure and stability of natural products.     

Bayesian Sparse Group Selection

This article proposes a Bayesian approach for the sparse group selection problem in the regression model. In this problem, the variables are partitioned into different groups. It is assumed that only a small number of groups are active for explaining the response variable, and it is further assumed that within each active group only a small number of variables are active. We adopt a Bayesian hierarchical formulation, where each candidate group is associated with a binary variable indicating whether the group is active or not. Within each group, each candidate variable is also associated with a binary indicator, too. Thus, the sparse group selection problem can be solved by sampling from the posterior distribution of the two layers of indicator variables. We adopt a group-wise Gibbs sampler for posterior sampling. We demonstrate the proposed method by simulation studies as well as real examples. The simulation results show that the proposed method performs better than the sparse group Lasso in terms of selecting the active groups as well as identifying the active variables within the selected groups. Supplementary materials for this article are available online.     

Synthesis and biological evaluation of substituted indazolyl amide derivatives as S-adenosyl-L-homocysteine hydrolase inhibitors

A series of novel amide derivatives bearing an indazole moiety were synthesized and evaluated for their in vitro S-adenosyl-L-homocysteine hydrolase (SAHase) inhibitory activity. Among these compounds, 8b, 8m, 8r and 8w showed better or similar inhibitory effects compared to the positive control aristeromycin. These results provide a novel lead for the discovery of more potent non-adenosine analogs as SAHase inhibitors.