Two new cycloartanes from the leaves of Combretum quadrangulare growing in Vietnam and their biological activities

Two new cycloartanes, combretanones G and H (1 and 2), were isolated from the leaves of Combretum quadrangulare. Their structures were elucidated by applying a set of spectroscopic methods, while their relative configurations were determined using DFT-NMR chemical shift calculations and subsequent assignment of DP4 probabilities. Compounds 1 and 2 are C-23/C-24 stereoisomers of the previously-reported euphonerin E. Both exhibited moderate cytotoxicity against three human cancer cell lines. Compound 2 was shown to be a potent antiparasitic. Our results confirm the traditional medicinal uses of Combretum quadrangulare in Vietnam.     

牛油果中化学成分的内部萃取电喷雾电离质谱检测

采用内部萃取电喷雾电离质谱(iEESI-MS)技术,以甲醇作为萃取溶剂,无需样品预处理,在优化条件下分别对牛油果果肉和果皮中化学成分进行快速直接鉴定,并考察了不同成熟度牛油果果肉中化学成分的差异.实验结果表明,在负离子检测模式下,从果肉中鉴定出棕榈酸、硬脂酸、棕榈油酸、油酸和亚麻酸等12种有效营养成分,从果皮中鉴定出儿茶素、绿原酸等11种营养成分.利用正交偏最小二乘判别分析法(OPLS-DA)对不同成熟度的牛油果果肉的iEESI-MS指纹谱图数据进行分析发现,此方法能够有效判别不同成熟程度的牛油果且5种化学成分差异显著.本方法无需样品预处理、样品耗量少、分析速度快(单个样品检测时间小于1 min)且操作简便,为植物有效营养成分和医用价值的开发提供了一种快速质谱分析新方法.     

海藻酸-磷脂微囊复合水凝胶的制备、表征及毒理学分析

采用薄膜分散法合成磷脂微囊,根据胶粒的双电层理论,通过在微囊中加入氯化锰、氯化钙和氯化镁电解质溶液,使微囊处于相对稳定的状态.研究发现加入氯化锰和氯化钙溶液,微囊胶体的粒径没有明显的变化,但加入一定浓度氯化镁溶液,其粒径明显变大.为了进一步增加磷脂微囊稳定性,将氯化锰、氯化钙、氯化镁磷脂微囊胶体分别与海藻酸钠(SA)溶液混合.结果表明,氯化镁与SA几乎不能形成水凝胶,氯化钙与SA形成水凝胶能力强于氯化锰.微囊胶体溶液中的磷脂酰丝氨酸(PS)可以与Ca~(2+)和Mg~(2+)键合形成PS-Ca~(2+)和PS-Mg~(2+),但不能与Mn~(2+)键合形成PS-Mn~(2+).对氯化钙磷脂微囊与海藻酸钠合成的复合水凝胶的形貌、溶胀率及细胞毒性进行了表征,结果表明,氯化钙与SA形成的水凝胶可以捕获胶体中磷脂微囊,且形貌规整,结构稳定,无细胞毒性.     

Formation of abnormal dual‐peak profiles in large tilt angle boron implantation

Large tilt angle (LTA) implantation has been employed in Si manufacturing processes in many applications, such as lightly doped drain and halo implant. The depth profile of boron ions usually consists of only single peak at incident angle of 0° with respect to the perpendicular of the silicon surface. However, an abnormal dual‐peak profile was observed at LTA (>40°) with incident energy of 160 keV. By using a Monte Carlo method to simulate the ion implant process, it was found that the projected range of boron ions agrees completely with the formation of the first peak position that is shallower in depth, while the cause for the second peak that corresponds with a depth much deeper in the Si substrate was unknown. During the simulation, it was also found that when the tilt angle was increased, the sputtering yields and Si displacements increased significantly, and this phenomenon indicates that during LTA implantation, Si damage may not be negligible anymore. The Si damage effect that was as due to either low Si density or transient Si displacement in the simulation could have led to partial incident boron ions penetrating much deeper into the Si substrate and thus, caused the emergence of the second peak. Copyright © 2016 John Wiley & Sons, Ltd.     

Isolation and structure determination of a new lasso peptide subterisin from Sphingomonas subterranea

A new lasso peptide named subterisin was isolated from the culture broth of Sphingomonas subterranea NBRC 16086^T. The molecular formula of subterisin was established as C₇₈H₁₂₁O₂₂N₂₁ based on accurate mass analysis. The chemical structure of subterisin was determined by 2D NMR experiments. The presence of macrolactam ring of Gly1–Glu8 was indicated by NOESY experiment and MS/MS analysis. The three-dimensional structure of subterisin in solution was established by calculation based on NMR data. The proposed biosynthetic gene cluster of subterisin was found on the genome of S. subterranea.     

水在二维g-C_3N_4纳米分离膜片层间的超快传输

正无机膜分离是环境、能源等领域的一项关键技术,对于解决人类可持续发展相关的许多重大问题都有重要意义,而提高膜分离效率则是该技术的关键所在。原则上,降低膜厚可提高通量,但同时会引起膜的机械性能和选择性变差等一系列问题。纳米材料制备技术及功能调控为构筑新型高     

Determination of k-factors by thermal neutron activation technique

The k_{o, Au}-factors of 10 elements have been determined by irradating the samples with thermal neutrons in the reactor thermal column. The proposed method has the advantage of eliminating the errors induced by the uncertainties of the neutron spectrum parameters and the nuclear data. The results obtained are in good agreement with the literature data.     

离子选择性电极法测定药剂中的头孢氨苄

基于头孢氨苄在０．１０ｍｏｌ／Ｌ ＮａＯＨ介质中,沸水浴降解２００ｍｉｎ后,能生成硫醇化合物,利用硫离子选择电极研究了测定头孢氨苄条件,其浓度在６．０×１０＾－５￣１×１０＾－２ｍｏｌ／Ｌ范围,电位Ｅ与浓度对数呈线性关系,并将此方法用于胶囊中头孢氨苄的测定,回收率为１０４．０％。     

新显色剂对羧基苯基重氮氨基偶氮苯的合成及与镉显色反应的研究

本文报道了新色剂对羟基苯基重氮氨基偶氮苯的合成。