非线性偏最小二乘导数分光光度法同时测定复方新诺明中二组分的含量

构造了导数光谱与多组分浓度间的非线性模型 ,以偏最小二乘法估计模型参数 ,建立了同时测定两组分的非线性偏最小二乘导数分光光度法 ,方法用于复方新诺明中磺胺甲唑SMZ(Sulfamethoxazole)和甲氧苄啶TMP(Trimethoprim)含量的测定 ,10份模拟样中SMZ ,TMP的回收率分别为 99 8%和 10 0 1% ,RSD分别为 1 3%和 1 6 %。结果明显好于线性偏最小二乘导数分光光度法。用该法测定复方新诺明片中的二组分含量测定结果与药典方法一致 ,该法为复方制剂的分光光度分析提供了更为理想的新途径。     

衰减全反射型电压传感器的理论和实验研究

提出了一种新型反射型聚合物波导电压传感器理论,并且进行了实验研究。这种电压传感器采用棱镜波导耦合结构,在棱镜下底面依次镀有金属膜一聚合物一金属膜三层结构。通过两层金属膜对极化聚合物加电压,利用聚合物材料电光效应和导模共振吸收峰对聚合物折射率的敏感特性,通过反射光强的测量来确定作用电压的变化值。实验中的测试电压范围是从-140V至 140V,得到的线性度值为0．991,电压测量的分辨力为0．1V,电压测量灵敏度系数为0．0011V^-1。实验表明这种电压传感器具有良好的线性和较高的灵敏度。     

Two new layered inorganic–organic hybrids: intercalation of 1,3,5-benzenetricarboxylate in lead bisphosphonate

Hydrothermal reactions of N-benzyl-iminobis(methylenephosphonic acid), C₆H₅CH₂N(CH₂PO₃H₂)₂ (H₄L), with lead(II) carbonate in the presence of butane diacid resulted in a new layered lead(II) amino-bisphosphonate, namely, Pb₃L(H₂L)·1.5H₂O 1. When 1,3,5-benzene-tricarboxylic acid (H₃BTC) was used instead of butane diacid, a new layered lead(II) amino-bisphosphonate containing noncoordinated H₃BTC molecules, Pb₃(HL)₂·2(H₃BTC)·2H₂O 2 was isolated. Compound 1 crystallizes in the monoclinic space group P2₁/c with cell dimensions of a=17.6776(14) Å, b=10.0111(8) Å, c=16.6017(13) Å, β=104.134(2)° and Z=4. Compound 2 crystallizes in triclinic space group P-1 with cell parameters of a=4.8797(4) Å, b=9.9736(7) Å, c=24.3631(17) Å, α=97.680(2)°, β=95.0000(10)°, γ=102.4340(10)° and Z=1. Both compounds feature a layered structure and have a same metal/ligand ratio of 3:2. Compound 1 contains two types of ligands with different charges, −2 and −4, respectively. The lead(II) ions are bridged by bisphosphonate ligands, resulting in a 〈100〉 layer. In compound 2, the interconnection of the lead(II) ions by bridging phosphonate groups resulted in a 〈001〉 layer, with the neutral H₃BTC ligand intercalated between two layers, forming hydrogen bonds with lattice water molecules, noncoordinated phosphonate or carboxylate groups. In both compounds, the phenyl groups of the ligands are orientated toward the interlayer space. TGA and IR spectra for both compounds have been also studied.     

钯催化合成嘧啶核苷衍生物的研究进展

嘧啶核苷衍生物在药物化学、生物探针和核酸化学的研究中具有重要的作用, 金属催化碳碳的形成广泛应用于嘧啶核苷衍生物的合成. 综述了钯催化的Sonogashira反应、Stille反应、Heck反应以及Hiyama反应在嘧啶类核苷衍生物合成中的应用.     

Tandem cyclization-[3+3] cycloaddition reactions of 2-alkynylbenzaldoxime: synthesis of fused 1,2-dihydroisoquinolines

Tandem cyclization-[3+3] cycloaddition of 2-alkynylbenzaldoximes with dimethyl cyclopropane-1,1-dicarboxylate co-catalyzed by AgOTf and Yb(OTf)₃ is described, which provides an useful method for the synthesis of tetrahydro-1,2-oxazine fused 1,2-dihydroisoquinolines.     

Effect of stoichiometric ratio of organic fuel to oxidizer on performance of La0.8Sr0.2CoO3 catalysts for CH4 combustion

Perovskite-type La_0.8Sr_0.2CoO₃ mixed oxides were prepared by d,l-alanine solution combustion synthesis and used successfully in CH₄ combustion as catalysts. These samples were characterized by means of XRD, FTIR, BET, and H₂-TPR methods. The effects of stoichiometric ratio (φ) of organic fuel to oxidizer on the structure and catalytic activities of the catalysts were studied. The results indicate that all La_0.8Sr_0.2CoO₃ mixed oxides with different φ have perovskite structures. Their structures and catalytic activities vary along with the change of φ. The catalytic activity of La_0.8Sr_0.2CoO₃ mixed oxide with φ = 1.52 is the best among all the samples, whose T ₅₀ and T ₁₀₀ (the temperatures of methane conversions reaching 50 and 100%, respectively) are respectively 470 °C and 550 °C, which can be explained in terms of the smaller of average crystal size, higher specific surface area, bigger lattice distortion, lower activation energy, and higher mobility of chemically adsorbed oxygen on the surface and vacancy of the catalysts.     

Transfer Volumes of Small Peptides from Water to Aqueous Xylitol Solutions at 298.15 K

Densities have been measured by an oscillating-tube densimeter for aqueous solutions of glycylglycine and glycylglycylglycine in aqueous xylitol solutions with xylitol mass fractions ranging from 0 to 0.15 at 298.15 K. Apparent molar volumes and limiting partial molar volumes have been used to calculate the corresponding transfer volumes from water to different concentrations of xylitol + water mixtures. The results are interpreted in terms of the cosphere overlap model.     

Solid/liquid- and vapor-phase interactions between cellulose- and lignin-derived pyrolysis products

Solid/liquid- and vapor-phase interactions between cellulose- and lignin (Japanese cedar milled wood lignin)-derived pyrolysis products were studied under the conditions of N₂/600 °C/40–80 s. A dual-space closed ampoule reactor was used to eliminate the solid/liquid-phase interactions, and careful comparison of the resulting data with those of the pyrolysis of the mixed samples gave some insights into the solid/liquid- and vapor-phase interactions separately. With the solid/liquid-phase interactions, the tar yields from both cellulose and lignin increased with the decreasing yields of the char fractions in a short pyrolysis time of 40 s (primary pyrolysis stage). Most of the identified tar components from cellulose and lignin increased in their yields. The vapor-phase interactions were significant at a longer pyrolysis time of 80 s (secondary reaction stage) when the methoxyl groups of the lignin-derived volatiles were cleaved homolytically. The vapor-phase interactions accelerated the gas formation from the cellulose-derived volatiles with suppressing the vapor-phase char formation of the lignin-derived volatiles. The yields of methane and catechols from lignin also increased greatly instead of the formation of o-cresols. Most of these influences are explained with a proposed interaction mechanism, in which the cellulose-derived volatiles act as H-donors while the lignin-derived volatiles (radicals) act as H-acceptors.     

Using support vector machines for prediction of protein structural classes based on discrete wavelet transform

The prediction of secondary structure is a fundamental and important component in the analytical study of protein structure and functions. How to improve the predictive accuracy of protein structural classification by effectively incorporating the sequence‐order effects is an important and challenging problem. In this study, a new method, in which the support vector machine combines with discrete wavelet transform, is developed to predict the protein structural classes. Its performance is assessed by cross‐validation tests. The predicted results show that the proposed approach can remarkably improve the success rates, and might become a useful tool for predicting the other attributes of proteins as well. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009     

Application of INAA in analysis of Chinese ancient greenish white porcelain

This paper reports the applications of INAA in analysis of Chinese ancient porcelain fired from early Northern Song dynasty (AD 1004–1127) to Late Yuan dynasty (AD 1320–1368) in Hutian Kiln. Minor and trace elements of 168 pieces of ancient porcelain bodies were determined by INAA. The results of factor analysis and some archaeological questions are also discussed in this paper.