Chemical constituents of Taraxacum formosanum

Three new compounds, taraxacine-A (1), taraxacine-B (2) and taraxafolin (3) together with twenty-five known compounds, which include two beta-carboline alkaloids, two indole alkaloids, two chlorophylls, two flavonoids, one coumarin, two triterpenoids, one monoterpenoid, one ionone, four steroids and eight benzenoids, were isolated and characterized from the fresh aerial parts of Taraxacum formosanum. Structures of new compounds were determined by spectral analysis.     

The constituents of the root and stem of Aristolochia heterophylla Hemsl

Seven new compounds, sodium aristolochate-VII (1), aristolactam-CIV (2), madolin-I (3), -J (4), -K (5), -L (6) and -M (7) together with 71 known compounds were isolated and characterized from the fresh root and stem of Aristolochia heterophylla Hemsl. Their structures were determined by spectral methods. Compound 8 was revised as aromadendrane-4beta, 10beta-diol by spectral data and single-crystal X-ray analysis.     

Polarized Raman Spectra VII Correlations and Assignments of Raman Lines in p-Polyphenyls

The Raman spectra of powdered biphenyl, p-terphenyl, and p-quaterphenyl are compared with each other and also with the Raman spectrum of benzene. Most Raman lines in polyphenyls can be considered as derived from normal vibrations in benzene. The intense lines are thus assigned and the correlations between them are established.     

Effect of seed layer on the growth and the consequent gas sensing characteristics of ZnO nanorod arrays using aqueous chemical growth

The ZnO nanorod arrays are grown on the sol–gel-derived seed layer through aqueous chemical growth, and then assembled as gas sensors for detecting carbon monoxide (CO). It is found that the structural and photoluminescent properties of the ZnO nanorod arrays are different as they are grown on seed layers annealed at different temperature (300–700 °C), which is ascribed to distinct growth kinetics of nanorods on the annealed seed layer. Moreover, the correlation between the exposed surface area and the defect density of those ZnO nanorod arrays points out the intrinsic (interior) defects can dominate the green emission instead of surface defects in the present study. Furthermore, the quantities of chemisorbed oxygen on ZnO nanorod arrays can be estimated through XPS analysis. Consequently, the influence of intrinsic defects and chemisorbed oxygen on the electrical properties and gas sensitivities of ZnO nanorod arrays has been clearly elucidated. It is demonstrated that the more adsorbed oxygen and an appropriate amount of intrinsic defects is advantageous to obtain superior CO gas sensitivity for ZnO nanorod arrays.     

Facile syntheses of 7,9-dimethoxypyrrolo[3,2,1-ij]quinolin-6-ones

The activated dimethoxypyrrolo[3,2,1-ij]quinolin-6-one ring system was synthesized via two approaches, starting from an indole and quinolin-4-one, respectively. Subsequent demethylation led to both monohydroxy- and dihydroxypyrrolo[3,2,1-ij]quinolin-6-ones.     

HI-13串列加速器辐射防护联锁系统改造

新建HI-13串列加速器辐射防护联锁系统采用PLC自动化控制,增加与优化了原系统的联锁控制逻辑,在充分保证人员辐射安全的同时,使系统状态显示更直观,操作更方便.     

Cloning, expression, and characterization of thermostable region of amylopullulanase gene from Thermoanaerobacter ethanolicus 39E

The bifunctional activities of α-amylase and pullulanase are found in the cloned recombinant amylopullulanase. It was encoded in a 2.9-kb DNA fragment that was amplified using polymerase chain reaction from the chromosomal DNA of Thermoanaerobacter ethanolicus 39E. An estimated 109-kDa recombinant protein was obtained from the cloned gene under the prokaryotic expression system. The optimum pH of the recombinant amylopullulanase was 6.0. The most stable pH for the α-amylase and pullulanase activity was 5.5 and 5.0, respectively. The optimum temperature for the α-amylase activity was 90°C, while its most stable temperature was 80°C. Regarding pullulanase activity, the optimum temperature and its most stable temperature were found to be 80 and 75°C, respectively. Pullulan was found to be the best substrate for the enzyme. The enzyme was activated and stabilized by the presence of Ca²⁺, whereas EDTA, N-bromosuccinimide, and α-cyclodextrin inhibited its bifunctional activities. A malto-2–4-oligosac-charide was the major product obtained from the enzymatic reaction on soluble starch, amylose, amylopectin, and glycogen. A single maltotriose product was found in the pullulan hydrolysis reaction using this recombinant amylopullulanase. Kinetic analysis of the enzyme indicated that the K _m values of α-amylase and pullulanase were 1.38 and 3.79 mg/mL, respectively, while the V _max values were 39 and 98 μmol/(min · mg of protein), respectively.     

The constituents of the root and stem of Aristolochia cucurbitifolia Hayata and their biological activity

Four new compounds, three phenanthrene derivatives, aristolochic acid-III methyl ester (1), cepharanone C (2), and sodium 7-hydroxyl-8-methoxyaristolate (3), and the benzoate derivative, sodium 3,4-dimethoxybenzoate (4), together with 53 known compounds were isolated and characterized from the fresh root and stem of Aristolochia cucurbitifolia. Their structures were elucidated by spectral analyses and chemical transformations. The cytotoxicity and antiplatelet activity of the isolated compounds are also discussed.     

Pb1－xMnxSe薄膜的光学特性

采用分子束外延的方法在BaF₂(111)衬底上制备出了高质量的Pb_1-xMn_xSe(0≤x≤0.0681)薄膜.X射线衍射结果表明，Pb₁-xMn_xSe薄膜为立方相NaCl型结构，没有观察到MnSe相分离现象，薄膜的取向为平行于衬底(111)晶面.晶格常数随着Mn含量的增加逐渐减小，Mn含量由Vegard公式得到.通 关键词： 1-xMn_xSe外延薄膜')" href="#">Pb_1-xMn_xSe外延薄膜 透射光谱 带隙 折射率