Comparative analysis of volatile constituents between recipe jingfangsan and its single herbs by GC‐MS combined with alternative moving window factor analysis method

Comparative analysis of volatile constituents between recipe jingfangsan and its single herbs was performed by GC‐MS combined with alternative moving window factor analysis (AMWFA), a new chemometric resolution method. Identification of the compounds was also assisted by comparison of temperature‐programmed retention indices (PTRIs) on the OV‐1 column with authentic samples. In total, 36, 29, and 42 volatile components in essential oil of Herba schizonepetae (HS), Radix saposhnikoviae (RS), and the recipe were respectively determined qualitatively and quantitatively, accounting for 81.80, 82.62 and 85.98% total contents of volatile oil of HS, RS, and the recipe respectively. Analysis by the method of AMWFA indicates that there are 22 common volatile constituents between the recipe and single herbal medicine HS, and 14 common volatile constituents between the recipe and single herb medicine RS. The experimental results also show that the volatile components of the recipe in number are almost addition of that of two single herbal medicines HS and RS, and are mainly from the single herbal medicine HS.     

Comparative analysis of volatile constituents in Citrus Reticulata Blanco using GC–MS and alternative moving window factor analysis

The similarities and differences of essential oil components in Album Citri Reticulatae (ACR), Cylindricae Citri Reticulatae (CCR), Folium Citri Reticulatae (FCR), Exocarpium Citri Grandis (ECG), Pericarpium Citri Reticulatae Viride (PCRV) and Pericarpium Citri Reticulatae (PCR) were investigated by GC–MS combined with a chemometric method named alternative moving window factor analysis (AMWFA). And temperature‐programmed retention indices (PTRIs) were used together with mass spectra for identification of the essential oil components. In essential oils of ACR, CCR, FCR, ECG, PCRV and PCR, 28, 26, 61, 62, 52 and 48 components were determined representing 93.13, 94.44, 93.53, 87.67, 99.03 and 98.03% of the total relative content, respectively. Also, the essential oils significantly differed both qualitatively and quantitatively. There were 14 common components among ACR, CCR, FCR, ECG, PCRV and PCR, their abundance varied in the ranges from 32.39% in FCR to 94.66% in PCRV. The results obtained may be helpful to the further study of pharmacological activity for their potential utilization as therapeutical agents.     

Design of a pressure sensor of 0–7 bar in fiber optic using MMI methodology

This research shows the possibility of measuring pressure in the range of 0–7 bar and the comparison against 2 commercial sensors. The technique used is based on the multimodal interference in a fiber optic singlemode–multimode–singlemode (SMS) to 1550 nm. The fiber optic is mounted on a plate of stainless steel AISI 316, where the bending of the plate will generate a curvature on the part of the multimodal fiber generating a decoupling of modes and this generates a low intensity to the output of the system.     

Yuan's alternative theorem and the maximization of the minimum eigenvalue function

LetA ₁ andA ₂ be two symmetric matrices of ordern×n. According to Yuan, there exists a convex combination of these matrices which is positive semidefinite, if and only if the functionxR ⁿ max {x ^T A ₁ x,x ^T A ₂ x} is nonnegative. We study the case in which more than two matrices are involved. We study also a related question concerning the maximization of the minimum eigenvalue of a convex combination of symmetric matrices.This research was partially supported by Dirección General de Investigación Científica y Técnica (DGICYT) under Project PB92-0615.     

Simultaneous determination of zinc,copper, lead,and cadmium in fuel ethanol by anodic stripping voltammetry using a glassy carbon–mercury-film electrode

A new, versatile, and simple method for quantitative analysis of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry is described. These metals can be quantified by direct dissolution of fuel ethanol in water and subsequent voltammetric measurement after the accumulation step. A maximum limit of 20% (v/v) ethanol in water solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Chemical and operational optimum conditions were analyzed in this study; the values obtained were pH 2.9, a 4.7-m thickness mercury film, a 1,000-rpm rotation frequency of the working electrode, and a 600-s pre-concentration time. Voltammetric measurements were obtained using linear scan (LSV), differential pulse (DPV), and square wave (SWV) modes and detection limits were in the range 10^–9–10^–8 mol L^–1 for these metal species. The proposed method was compared with a traditional analytical technique, flame atomic absorption spectrometry (FAAS), for quantification of these metal species in commercial fuel ethanol samples.     

Caloric properties of mixtures of refrigerants R22 / R114

The nonazeotropic refrigerant mixture chlorodifluoromethane (R22) and 1,2-dichlorotetrafluoroethane (R114) has been frequently suggested as a working fluid in cooling systems and heat pump applications. However, especially for mixtures exact and reliable measurements of the caloric properties are often missing, so that calculations with equations of state yield results of great uncertainty. In spite of the CFC-ozone problem of this mixture it can be considered as an exemplary mixture to set up accurate equations of state.

Therefore measurements with an isenthalpic throttle calorimeter were carried out for three different compositions of the mixture. The measured isenthalps could be reproduced within the experimental accuracy by polynomials. Together with the specific heat capacity of the pure components the measurements lead to several caloric properties in the liquid-, vapour- and critical region. The caloric properties can also be calculated by equations of state (EOS). It turned out that the results obtained from Bender's EOS with interaction parameters fitted to the experiments lead to a good agreement with the experimental data.     

Convective boiling of halocarbon refrigerants flowing in a horizontal copper tube – an experimental study

An experimental study of convective boiling of refrigerants R-22, R-134a and R-404A in a 12.7 mm internal diameter, 2 m long, horizontal copper tube has been performed. Experiments involved a relatively wide range of operational conditions. Experiments were performed at the evaporating temperatures of 8°C and 15°C. Quality, mass velocity and heat flux varied in the following ranges: 5% to saturated vapor, 50–500 kg/(s m²); and 5–20 kW/m². Effects of these physical parameters over the heat transfer coefficient have been investigated. High quality experiments were also performed up to the point of the tube surface dryout, a mechanism which was investigated from the qualitative point of view. Two heat transfer coefficient correlations from the literature have been evaluated through comparisons with experimental data. Deviations varied in the range from −25% to 42%.     

转换移动窗口因子分析法用于中药组合前后成分变化分析

以正十四烷为内标,采用气相色谱-质谱(GC/MS)联用技术对中药甘草(GUF)、甘遂(EKL)单味药材,以及其组成的药对(GUF-EKL)的挥发成分进行测定,基于一种新的化学计量学方法——转换移动窗口因子分析法(AMWFA)和直观推导式演进特征投影法(HELP)对产生的二维色谱/质谱数据同时进行分辨和解析,获取各个组分的纯色谱曲线和质谱,根据分辨得到的纯质谱在质谱库中进行相似检索以实现对组分的定性。利用AMWFA对组合前后的成分进行归属分析,然后采用面积归一法进行定量。分别在甘草、甘遂及其药对中鉴定出52、51和63个成分,占各自挥发油成分的84%、90%和75%。     

三元混合制冷剂R290+R600a+N2汽液相平衡实验研究

在氢气液化工艺中,预冷循环是重要的一环,其中混合制冷剂(mixed refrigerant,MR)预冷循环是单位能耗比较低的,故对MR性能的优化显得尤为重要.为此利用液相单相循环法搭建汽液相平衡(Vapor-liquid equilibrium,VLE)实验系统,研究了R290+R600a+N₂三元体系的VLE性质,在273.15 K～323.15 K的温度范围内,对三元混合工质R290+R600a+N₂进行实验研究,并获得18组实验数据.同时使用Peng-Pobinson-Stryjek-Vera (PRSV)状态方程结合van der Waals(vd W)混合法则对R290+R600a、R290+N₂、R600a+N₂三组二元体系的VLE文献数据进行了拟合计算,得到二元交互作用系数,拟合结果与文献数据吻合良好.以此为基础,推算该三元体系的VLE性质.最后将实验数据与计算结果对比表明,体系压力平均相对偏差AARDp为0.85%,系统组分R290、R600a和N₂的气相平均绝...     

肿瘤抑制因子WT1对人的诱导型一氧化氮合成酶基因的转录调节作用

将人的诱导型一氧化氮合成酶(hiNOS)启动子构建在带荧光素酶基因的载体pGL3-basic上, 构建成用荧光素酶为系统的启动子, 以研究载体p8.3iNOS. 结果显示, 肾母细胞肿瘤抑制因子(WT1)能够有效地抑制hiNOS启动子的转录; 且WT1的4个选择性剪接本的抑制效果有所不同, 其中WT1(-/-)在两种肝癌细胞(HepG2和Hep3B)中对hiNOS的表达均具有最强的抑制作用, 并且抑制效果具有剂量依赖性, 用Western blot检测结果进一步证实HepG2细胞中WT1(-/-)过量表达能下调hiNOS表达. 以上结果说明WT1在肝癌细胞中对人的hiNOS具有转录调节作用.