The diphasic nc-Si/a-Si : H thin film with improved medium-range order

A series of silicon film samples were prepared by plasma enhanced chemical vapor deposition (PECVD) near the threshold from amorphous to nanocrystalline state by adjusting the plasma parameters and properly increasing the reactions between the hydrogen plasma and the growing surface. The microstucture of the films was studied by micro-Raman and Fourier transform infrared (FTIR) spectroscopy. The influences of the hydrogen dilution ratio of silane (R-H = [H-2]/[SiH4]) and the substrate temperature (T-s) on the microstructural and photoelectronic properties of silicon films were investigated in detail. With the increase of RH from 10 to 100, a notable improvement in the medium-range order (MRO) of the films was observed, and then the phase transition from amorphous to nanocrystalline phase occurred, which lead to the formation of diatomic hydrogen complex, H-2* and their congeries. With the increase of T-s from 150 to 275 degreesC, both the short-range order and the medium range order of the silicon films are obviously improved. The photoconductivity spectra and the light induced changes of the films show that the diphasic nc-Si/a-Si:H films with fine medium-range order present a broader light spectral response range in the longer wavelength and a lower degradation upon illumination than conventional a-Si:H films. (C) 2004 Elsevier B.V. All rights reserved.

五种毛壳霉属和曲霉属真菌代谢产物及细胞毒活性

毛壳霉属(Chaetomium)和曲霉属(Aspergillus)真菌产生多种具有生物活性的化合物。为系统阐明两属微生物的次生代谢物，对三种毛壳霉、两种曲霉真菌分别进行固态发酵，以色谱和波谱技术研究发酵物中的成分，分离鉴定了51个化合物，其中23个为新化合物，测试了部分化合物对肿瘤细胞的活性。 1、从螺卷毛壳霉（C. cochloides）固态发酵物中分离鉴定了11个化合物，3个新化合物为螺卷毛壳霉素A~C（1~3）。化合物1、3及dethio-tetra (methylthio) chetomin（4）对Bre-04、Lu-04和N-04细胞株生长抑制的GI50值为0.05~7.0 μg/mL。 2、从印度毛壳霉（C. indicum）固态发酵物中鉴定的三个异喹啉生物碱印度毛壳霉素A~C（12~14）代表两类骨架新颖的异喹啉生物碱。 3、从巴西毛壳霉（C. brasiliense）固态发酵物中鉴定了11个化合物，其中Mollicellins I~J（15~16）、2-Hydroxymethyl-6-methylmethyleugenin（19）为新化合物。化合物16和Mollicellin H（18）对Bre-04、Lu-04、N-04细胞株生长抑制的GI50值在2.5~8.6 μg/mL。 4、从土曲霉（A. terreus）固态发酵物中鉴定了18个化合物。5个为新化合物为Terretonin A~D（24~27）和Asterrelenin（28），24~27为二倍半萜化合物，28为吲哚生物碱。 5、从杂色曲霉(A. versicolor）固态发酵物中鉴定了16个化合物。9个新的化合物Brevianamides K~N (40~43)、Averins A~C (44~46)和Glyanphenines A~B (47~48)代表三种类型的生物碱。 6、综述了1997－2007年间新的二倍半萜的研究进展。 The fungi of the genera Chaetomium and Aspergillus produce various secondary metabolites with biological activities. In order to systematically study the secondary metabolites, the solid-state fermented rice culture of three species of Chaetomium and two of Aspergillus were chemically studied. By the means of chromatograhy and spectroscopy, 55 compounds were isolated and identified, among of them 23 were new ones. The biological activities of some compounds were investigated. 1. From the fungus C. cochliodes, three new epipolythiodioxopiperazines, chaetocochins A-C (1-3) were isolated, together with 8 known ones (4-11). Compounds 1, 3 and 4 showed growth inhibitory effects against cancer cell lines Bre-04, Lu-04 and N-04 with GI50 values from 0.05 to 7.0 μg/mL. 2. Three novel isoquinolines Chaetoindicins A-C (12-14) were isolated and identified from the fungus C. indicum. Chaetoindicin A, Chaetoindicins B-C represented two classes of novel carbon skeletons. 3. Three new compounds, Mollicellins I-J (15-16), and 2-hydroxymethyl-6-methylmethyleugenin (19), were isolated from C. brasiliense. Compound 16 and Mollicellin H (18) showed growth inhibitory effects against cancer cell lines Bre-04, Lu-04 and N-04 with GI50 values from 2.5 to 8.6 μg/mL. 4. Eighteen compounds were isolated from the fungus A. terreus. Terretonin A-D（24 - 27）and Asterrelenin（28） are new compounds belonging to sesterterpoids and indole-ralated alkaloid, respectively. 5. From the fungus A. versicolor, sixteen secondary metabolites, including nine new ones, Brevianamides K-N (40-43), Averins A-C (44-46), and Glyanphenines A-B (47-48), were isolated and identified. Brevianamides K-N (40-43), Averins A-C (44-46), and Glyanphenines A-B (47-48) represented three classes of alkaloids. 6. New sesterterpenes and their bioactivities reported from 1997 to 2007 were summarized.

高压条件下高能重离子辐照材料研究进展

高能重离子辐照处于高压条件下材料的研究,是随着高能重离子加速器技术的快速发展而出现的一个新的研究领域,研究结果涉及材料学、地质学、地质年代学、核废料处理学等学科。简要介绍最近几年国内外在高能重离子辐照高压条件下材料研究领域的研究现状及已取得的结果,并对未来在兰州重离子加速器冷却储存环(HIRFL-CSR)上开展相关研究工作的前景作了展望。

PE文件隐型加壳技术的研究与实现

通过对PE(portable executable)文件格式的了解,编写PE分析工具对文件内部结构进行分析。详细介绍了对PE可执行文件加壳的全过程,在此过程中巧妙地使用MD5、CRC32等成熟的hash算法及防API断点跟踪等多种反破解技术,并采用自动隐藏加密方案,大大地提高了软件的保护力度。

H_2O分子在不同电荷态的重离子作用下的离化

利用含时密度泛函理论和局域密度近似方法,计算了H2O分子在速度为12.5a0/fs的重离子C+和C2+作用下产生的各种电荷态的H2O分子离子的几率、平均逃逸电子数和偶极矩的变化随时间的演化。计算结果表明,在重离子势最大时,电偶极矩的变化最大,重离子的电荷态越高,得到高电荷态H2O分子的几率越大;重离子远离分子时,电偶极矩的变化趋于平缓。