硫酸溶液中Pt(111)电极面上存在SO2-4的XPS证据

Pt（111）电极在硫酸溶液中的循环伏安图已被多个研究小组所得到[1-3]．对图上出现的高于正常氢吸脱附电位出现的两个电流峰（Clavilier等[1]首次发现并称之为异常峰）的解释至今没有得到一致意见．分歧焦点是异常峰的出现是由于强键合吸附氢还是吸附其它阴离子所致·本文用XPS和LEED研究异常峰电位处浮出的Pt（111）电极表面，发现尖锐异常峰的出现是由于表面上吸附了离子．1实验文献＊中详细说明了实验所用装置．主要部份是把装有XPS、LEED、MS、Ar“枪的超高真空腔门HV）与测量循环伏安图的腔（EC）联在一起·UHV中基压强为4x…     

A new sesquiterpene from hairy root culture of Artemisia annua

<正>A new sesquiterpene(Z)-7-acetoxy-methyl-11-methyl-3-methylenedodeca-1,6,10-triene(AMDT) was isolnted and identified from the methanol extract of the hairy root culture of Artemisia annua.The structure of AMDT was determined based on the analysis of spectroscopic data,notably of the 2D NMR spectra.This new compound showed cytotoxicity against human tumor cell lines 95-D and HeLa with IC_(50) values of 27.08 and 20.12μmol/L,respectively.     

Rapid Extraction of Essential Oil from Dried Cinnamomum cassia Presl and Forsythia suspensa(Thunb.)Vahl by Ionic Liquid Microwave Extraction

Ionic liquid (IL) was used as the microwave absorption medium to extract essential oils from dried Cinnamomum cassia Presl and Forsythia suspensa (Thunb.) Vahl, and the ionic liquid microwave extraction (ILME) was developed. Some experimental parameters for ILME were examined. The proposed method was compared with other methods, including hydrodistillation (HD), microwave hydrodistillation (MHD), solvent‐free microwave extraction (SFME) and improved solvent‐free microwave extraction (ISFME). Experimental results showed that compared with other extraction methods the ILME had some advantages, such as time‐saving, simplicity and usage of green solvents. The extraction time was less than 18 min at the microwave power of 440 W and 1.5 mL of ionic liquid was required. The constituents of essential oils obtained by the five methods are not obviously different.     

A novel hydrazine electrochemical sensor based on the high specific surface area graphene

An ultrasensitive platform is presented for the determination of hydrazine by combining the high specific surface area and higher electrical conductivity of poly(sodium styrenesulfonate) (PSS) graphene nanocomposite film with amperometric detection. The PSS-graphene were synthesized by the Hummers method and used to modify a glassy carbon electrode. The material was characterized by scanning electron microscopy and is found to be suitable for sensing hydrazine. The overpotential of hydrazine on the modified electrode is 0.31 V which is lower than in many electrochemical sensors. The calibration curve for hydrazine is linear in the range from 3.0 to 300 µmol L^?1, and the detection limit is as low as 1 µmol L^?1. This is the first report in which such a high sensitivity and low limit of detection has been achieved. It is concluded that PSS graphene represents an efficient electron mediator for sensing hydrazine.     

Four New Nortriterpenoids from Schisandra lancifolia

Four new highly oxygenated nortriterpenoids, lancifodilactones O–R ( 1 – 4 ), together with six known ones, i.e., 5 – 10 , were isolated from the leaves and stems of Schisandra lancifolia. Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments and mass spectrometry. Compounds 1 – 3 were evaluated for their cytotoxicity against NB4, A549, SHSY5Y, PC‐3, and MCF‐7 cell lines. No compounds exhibited significant cytotoxicity, the IC₅₀ values being above 50 μM .     

壳聚糖膜的量子化学计算

采用Gaussian92程序，用AM1半经验量子化学方法优化壳聚糖膜模型的分子结构，在此基础上用量子化学从头算STO-3G方法计算，研究了壳聚糖-戊二醛的阳离子膜和阴离子膜的几何构型、能量、键序和电子迁移，讨论了膜形成的成键形式和膜的结构及稳定性     

Mixed Cu2Se Hexagonal Nanosheets@Co3Se4 Nanospheres for High-Performance Asymmetric Supercapacitors

Rational designing and constructing multiphase hybrid electrode materials is an effective method to compensate for the performance defects of the single component. Based on this strategy, Cu₂Se hexagonal nanosheets@Co₃Se₄ nanospheres mixed structures have been fabricated by a facile two-step hydrothermal method. Under the synergistic effect of the high ionic conductivity of Cu₂Se and the remarkable cycling stability of Co₃Se₄, Cu₂Se@Co₃Se₄ can exhibit outstanding electrochemical performance as a novel electrode material. The as-prepared Cu₂Se@Co₃Se₄ electrode displays high specific capacitance of 1005 F g⁻¹ at 1 A g⁻¹ with enhanced rate capability (56 % capacitance retention at 10 A g⁻¹), and ultralong lifespan (94.2 % after 10 000 cycles at 20 A g⁻¹). An asymmetric supercapacitor is assembled applying the Cu₂Se@Co₃Se₄ as anode and graphene as cathode, which delivers a wide work potential window of 1.6 V, high energy density (30.9 Wh kg⁻¹ at 0.74 kW kg⁻¹), high power density (21.0 Wh kg⁻¹ at 7.50 kW kg⁻¹), and excellent cycling stability (85.8 % after 10 000 cycles at 10 A g⁻¹).     

Phytochemistry and Pharmacological Activities of the Diterpenoids from the Genus Daphne

There are abundant natural diterpenoids in the plants of the genus Daphne from the Thymelaeaceae family, featuring a 5/7/6-tricyclic ring system and usually with an orthoester group. So far, a total of 135 diterpenoids has been isolated from the species of the genus Daphne, which could be further classified into three main types according to the substitution pattern of ring A and oxygen-containing functions at ring B. A variety of studies have demonstrated that these compounds exert a wide range of bioactivities both in vitro and in vivo including anticancer, anti-inflammatory, anti-HIV, antifertility, neurotrophic, and cholesterol-lowering effects, which is reviewed herein. Meanwhile, the fascinating structure–activity relationship is also concluded in this review in the hope of providing an easy access to available information for the synthesis and optimization of efficient drugs.     

Study on the degeneracy of antisense peptides using affinity chromatography

The degeneracy of antisense peptides was studied by high-performance affinity chromatography. A model sense peptide (AAAA) and its antisense peptides (CGGG, GGGG, RGGG, SGGG) were designed and synthesized according to the degeneracy of genetic codes. An affinity column with AAAA as the ligand was prepared. The affinity chromatographic behaviors of antisense peptides on the column were evaluated. The results indicated that model antisense peptides have clear retention on the immobilized AAAA affinity column. RGGG showed the strongest affinity interaction. Similar result was obtained from another experiment that Arg-substituted antisense peptide of fusion peptide (1-11) of influenza virus A was also shown the highest affinity binding to immobilized fusion peptide.     

A HREELS study of the adsorption of formic acid on slightly oxidized Nb(110) surface

An investigation has been made on the adsorption and decomposition of formic acid on slightly oxidized Nb(110) surface (0/Nb atom ratio = 0.2) using high resolution electron energy loss spectroscopy (HREELS),and a corresponding surface reaction mode is given.At 140 K,formic acid of low exposure on such an Nb(110) surface decomposed to formate,which bonded on Nb in monodentate configuration,simultaneously some formate decomposed to CO,which adsorbed on the surface.Formic acid multilayers formed when the exposure was high.While the temperature was increased to above 190 K,multilayer formic acid desorbed,and the surface was covered with mon-odentate-bonded formate and CO.In the temperature range of 250-300 K,chemisorbed formate changed from monodentate configuration into bridging configuration and CO molecules disappeared.The decomposition of formate at higher temperatures led to the oxidation of Nb.The formate formed in the high exposure case was so stable that it did not decompose even the temperature wa