TiO2／Ti／TiO2半导体隔片光电化学电池的性能

研究了半导体隔片光电化学电池(SC-SEP)中光池溶液的pH、暗池溶液的氧化还原电对以及两池中的暗电极对电池的开路电压、光生电压、短路光电流和光伏安特性的影响。对它们的影响机制进行了初步分析。通过合理选择电池体系,SC-SEP的性能可比单隔室的光电化学电池(PEC)优越。     

Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking

Using cesium lead halide perovskite nanocrystals, CsPb(Cl/Br)_3, as a light absorber, we report a highly effective UV and blue light blocking film. The CsPb(Cl/Br)_3 nanocrystals are well dispersed in the ethyl cellulose(EC) matrix to compose a UV and blue light shielding film, and the absorption edge of the film is tunable by adjusting Cl to Br ratio using anion exchange. The CsPbCl_2 Br-EC film exhibits a transmittance of 5% at 459 nm, 90% at 478 nm and 95% in the range of 500–800 nm, which makes it excellent for UV and blue light shielding. In addition, the as-prepared EC-CsPb(Cl/Br)_3 film shows excellent photostability under UV irradiation. Results demonstrate that this EC-CsPb(Cl/Br)_3 based materials with sharp absorbance edges, tunable blocking wavelength, and high photostability can be useful for the applications in UV and blue light blocking and optical filters     

2A12-T6铝合金表面双-(γ-三乙氧基硅丙基)四硫化物薄膜的特性

采用傅立叶变换红外光谱分析了2A12-T6铝合金表面自组装双-(!-三乙氧基硅丙基)四硫化物硅烷偶联剂(SCA)薄膜结构特征,并采用电化学极化曲线评价了薄膜的耐蚀性能.结果表明,铝材表面自然晾干,SCA薄膜分子之间主要通过氢键连接,腐蚀电流密度减小1个数量级以上.120℃的加热处理促进铝板表面通过SiOSi链接而形成SCA网状薄膜结构,并通过在界面上形成SiOAl界面相结构而与铝板表面牢固连接,腐蚀电流密度降低2个数量级以上.SCA乙醇溶液浸泡处理10min比浸泡2s～1min的铝板表面SCA薄膜内氢键缔合羟基要多.     

化学模式识别技术评价中药厚朴质量的研究

本文对不同产地和市售的二十四种厚朴药材及饮片的萃取液进行了高效液相色谱、气相色谱及紫外光谱分析;对所得数据用主成分分析进行分类,概括出不同样品化学成分的异同,认为大叶木兰可做为厚朴的代用品,而在陕西安康购得的样品不应做厚朴使用,后者经生药学鉴定为厚朴伪品凹叶木兰。化学模式识别技术可为寻找药材的代用品、评价中药质量及鉴定伪劣药材提供依据。     

Electron propagator theory study of N-/O-methylglycine conformers

The low-lying conformers of N-/O-methylglycine are studied by ab initio calculations at the B3LYP, MP3, and MP4(SDQ) levels of theory with the aug-cc-pVDZ basis set. The conformers having the intramolecular hydrogen bonds N-H...O=C or O-H...N are more stable than the others. Vertical ionization energies for the valence molecular orbitals of each conformer predicted with the electron propagator theory in the partial third-order quasiparticle approximation are in good agreement with the experimental data available in the literatures. The relative energies of the conformers and comparison between the simulated and the experimental photoelectron spectra demonstrate that there are at least three and two conformers of N- and O-methylglycine, respectively, in the gas-phase experiments. The intramolecular hydrogen bonding O-H...N effects on the molecular electronic structures are discussed for the glycine methyl derivatives, on the basis of the ab initio electronic structure calculations, natural orbital bond, and atoms-in-molecules analyses. The intramolecular hydrogen bonding O-H...N interactions hardly affect the electronic structures of the O-NH2-CH2-C(=O)-O-CH3 and alpha-methylated NH2-CH2-C(CH3)OOH conformers, while the similar intramolecular interactions lead to the significantly lower-energy levels of the highest occupied molecular orbitals for the N-(CH3-NH-CH2-COOH) and beta-methylated (NH2-CH2-CH2-COOH) conformers.     

Selective hydrogenation by Pd nanoparticles embedded in polyelectrolyte multilayers

Alternating adsorption of poly(acrylic acid) and a polyethylenimine-Pd(II) complex on alumina and subsequent reduction of Pd(II) by NaBH4 yield catalytic Pd nanoparticles embedded in multilayer polyelectrolyte films. The polyelectrolytes limit aggregation of the particles and impart catalytic selectivity in the hydrogenation of alpha-substituted unsaturated alcohols by restricting access to catalytic sites. Hydrogenation of allyl alcohol by encapsulated Pd(0) nanoparticles can occur as much as 24-fold faster than hydrogenation of 3-methyl-1-penten-3-ol. Additionally, the nanoparticle/polyelectrolyte system suppresses unwanted substrate isomerization, when compared to a commercial palladium catalyst. Selective diffusion through poly(acrylic acid)/polyethlyenimine membranes suggests that hydrogenation selectivities are due to different rates of diffusion to nanoparticle catalysts. First-order kinetics are also consistent with a diffusion-limited mechanism. Further exploitation of the versatility of polyelectrolyte films should increase selectivity in hydrogenation as well as other reactions.     

STUDY ON THE SYNTHESIS AND PROPERTIES OF MACRORETICULAR IPN POLYACRYLAMIDE—POLY(VINYL—ETHYLENEDIAMINE)CHELATE SORBENTS

A new series of MR-IPN polyacrylamide—poly(vinyl-ethylenediamine)chelatesorbents were prepared by the reaction of ethylenediamine with MR-IPN matrixes.The newchelate sorbent showed good sorption properties for auric and platinic ions.     

The preparation and fluorescence properties of europium nanoparticles

A new structured metallic nanomaterial of europium nanoparticle was prepared using tannic acid as the reductive agent,and nanoeuropium protein conjugates were synthesized by the method of lipoic acid modification on the surface of nanoparticle,which opens a new field of application of lanthanides in nanotechniques.Their properties were also characterized by UV-vis absorption spectroscopy,transmission electron microscopy (TEM),and fluorescence spectroscopy.The europium nanoparticle and its protein conjugates solution were stable and water-soluble.The fluorescence intensity of the composite europium nanoparticles was significantly increased in the presence of trace protein,and was linear proportional to the concentration of proteins under optimum conditions.According to this,a fluorimetric method for the determination of protein was developed in this paper.     

Two New Steroidal Glycosides from Fermented Leaves of Agave americana

Two new spirostanol glycosides named agamenoside A and B, ere isolated from the fermented leaves of Agave americana. Their structures were elucidated as (23S,25R)-5α-spirostan-3β,6α，23－triol 3-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside(1) and (25R)-5α-spiro-stan-3β,6α-diol 3-O-β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyra-nosyl-(1→4)-β-D-galactopyranoside(2) by a combination of chemical and spectral methods.     

Fingerprint quality control of Tianjihuang by high-performance liquid chromatography-photodiode array detection

A novel, simple and accurate fingerprint method was developed using high-performance liquid chromatography-photodiode array detection (HPLC-DAD) for the quality control of Hypericum japonicum thunb (Tianjihuang), a Chinese herbal medicine used for the treatment of several bacterial diseases, infectious hepatitis, gastrointestinal disorder, internal hemorrhage and tumors. For the first time, the feasibility and advantages of employing chromatographic fingerprint were investigated and demonstrated for the evaluation of Tianjihuang by systematically comparing chromatograms with a professional analytical software recommended by State Food and Drug Administration (SFDA). Our results revealed that the chromatographic fingerprint combining similarity evaluation could efficiently identify and distinguish raw herbs of Tianjihuang from different sources. The effects resulted from collecting locations, harvesting time and storage time on herbal chromatographic fingerprints were also examined.