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.     

室温离子液体EMIES的标准生成焓

在(298.15 ±0.01) K下用转动弹热量计测定了离子液体硫酸乙酯-1-甲基-3-乙基咪唑(EMIES)及合成它的原料1-甲基咪唑的恒容燃烧热,通过计算得到它们的标准燃烧焓 分别为(－2671±2) 和(－286.3±0.5) kJ·mol－1;标准生成焓 分别为(－3060±3) kJ·mol－1和(－2145±4) kJ·mol－1.结合文献上硫酸二乙酯的标准生成焓数据,得到了合成离子液体EMIES的反应热(－102.3±1.0) kJ·mol－1,与合成实验中观察到的强烈放热现象是一致的.根据离子液体EMIES的热容数据,计算了不同温度下EMIES的标准生成焓.     

Two new megastigmane O-glucopyranosides from the leaves of Broussonetia papyrifera

Two new megastigmane O-glucopyranosides,named (2R,3R,5R,6S,9R)-3-hydroxy-5,6-epoxy-β-ionol-2-O-β-D-glucopyrano- side(1) and (2R,3R,5R,6S,9R)-3-hydroxyl-5,6-epoxy-acety-β-ionol-2-O-β-D-glucopyranoside(2) together with six known mega- stigmanes,were isolated from the leaves of Broussonetia papyrifera (Linn.) Vent.Their structures were established by chemical methods and spectroscopic techniques including 2D NMR.     

Low‐Temperature Facile Template Synthesis of Crystalline Inorganic Composite Hollow Spheres

This report presents a facile approach for the low‐temperature synthesis of crystalline inorganic‐oxide composite hollow spheres by employing the bulk controlled synthesis of inorganic‐oxide nanocrystals with polymer spheres as templates. The sulfonated polystyrene gel layer can adsorb the target precursor and induce inorganic nanocrystals to grow on the template in situ. The crystalline phase and morphology of the composite shell is tunable. By simply adjusting the acidity of the titania sol, crystalline titania composite hollow spheres with tunable crystalline phases of anatase, rutile, or a mixture of both were achieved. The approach is general and has been extended to synthesize the representative perovskite oxide (barium and strontium titanate) composite hollow spheres. The traditional thermal treatment for crystallite transformation is not required, thus intact shells can be guaranteed. The combination of oxide properties such as high refractive index, high dielectric constant, and catalytic ability with the cavity of the hollow spheres is promising for applications such as opacifiers, photonic crystals, high‐κ‐gate dielectrics, and photocatalysis.     

Ni添加对0.4Zr0.1V1.1Mn0.5Cr0.1合金的相结构和电化学性能的影响

本文通过XRD、SEM、EDS研究了Ti_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1Ni_x(x=0，0.2，0.4，0.6，0.8)合金的相结构和电化学性能。该合金系由BCC结构的V基固溶体主相和六方结构的C14 Laves第二相组成，Ni能够促进第二相的生成，Ni含量的增加导致了各相中的化学组成和晶格参数的变化，并通过电化学方法研究了Ni含量对_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1合金电极的最大放电容量、自放电性能、高倍率放电性能、循环稳定性能等的影响。     

涂料中甲醛的分光光度测定新方法

在FeCl3存在的盐酸介质中,甲醛与蛋白胨反应生成紫色化合物,最大吸收波长555 nm,甲醛浓度在1~25μg/10 mL范围内,吸光度与浓度成线性关系,线性相关系数r2=0.9997,检出限0.05μg/mL。用本法测定经活性炭脱色的水溶性涂料中的甲醛含量,回收率为96.46%~103.32%,相对标准偏差(n=6)为1.36%~2.09%。     

ZrO2-TiO2-CeO2的制备及其在NH3选择性催化还原NO中的应用

采用共沉淀法制备了载体材料TiO2、ZrO2-TiO2及ZrO2-TiO2-CeO2, 并利用X射线衍射(XRD)实验、比表面积测定(BET)、程序升温脱附(NH3-TPD)、储氧性能测定(OSC)及程序升温还原(H2-TPR)等方法对三种载体材料进行了表征. 结果表明, ZrO2-TiO2-CeO2具有较多的表面强酸位, 并具有一定的储氧性能和较强的氧化还原性能. 以三种材料为载体, 制备了质量分数分别为1%、9%的V2O5、WO3的整体式催化剂. 研究了三种催化剂在富氧条件下用NH3选择性催化还原NO的催化性能. 结果表明, 以ZrO2-TiO2-CeO2为载体的催化剂在反应空速为10000 h-1, 275 ℃时, NO的转化率接近100%, 具有最好的催化活性,并有良好的应用前景。     

De novo sequencing of tryptic peptides sulfonated by 4-sulfophenyl isothiocyanate for unambiguous protein identification using post-source decay matrix-assisted laser desorption/ionization mass spectrometry

A simple method of solid-phase derivatization and sequencing of tryptic peptides has been developed for rapid and unambiguous identification of spots on two-dimensional gels using post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The proteolytic digests of proteins are chemically modified by 4-sulfophenyl isothiocyanate. The derivatization reaction introduces a negative sulfonic acid group at the N-terminus of a peptide, which can increase the efficiency of PSD fragmentation and enable the selective detection of only a single series of fragment ions (y-ions). This chemically assisted method avoids the limitation of high background normally observed in MALDI-PSD spectra, and makes the spectra easier to interpret and facilitates de novo sequencing of internal fragment. The modification reaction is conducted in C(18) microZipTips to decrease the background and to enhance the signal/noise. Derivatization procedures were optimized for MALDI-PSD to increase the structural information and to obtain a complete peptide sequence even in critical cases. The MALDI-PSD mass spectra of two model peptides and their sulfonated derivatives are compared. For some proteins unambiguous identification could be achieved by MALDI-PSD sequencing of derivatized peptides obtained from in-gel digests of phosphorylase B and proteins of hepatic satellite cells (HSC).     

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.     

CBS法合成光学活性二茂铁基醇

以非天然氨基酸合成的手性β-氨基醇(4a～4c)为催化剂，用于不对称硼烷还原反应来合成光学活性的二茂铁基醇(1a～1e)，对映体过量值高达96%。