Separation of Photosynthetic Pigments by High-performance Liquid Chromatography: Comparison of Column Performance,Mobile Phase,and Temperature

High-performance liquid chromatography (HPLC) has been commonly used as method of separating and identifying photosynthetic pigments such as chlorophylls and carotenoids because of such advantages as speed, high resolution and sensitivity. In this technique, high separation relies largely on the type of column material. This study compared the efficiency of five reverse-phase columns, C8, C18, C18 monolithic, π-NAP, and cholester, for separation of photosynthetic pigments at several fixed conditions of mobile phase and temperature. This investigation also analysed the parameters of Δt_R and t_R ratio for selected pigments and resolution for structural isomers, such as α- and β-carotene. Among above columns tested, cholester column is suitable for separation of pigments not only for a broad range of polarity, but also for hydrophobic pigments in a simple mobile phase. This finding can help in the selection of column and HPLC parameters in separating photosynthetic pigments.     

大气颗粒物重金属形态分析

重金属作为大气颗粒物中重要有毒组分之一,其总量和存在形态与颗粒物重金属的健康风险密切相关。因此,颗粒物重金属形态分析对深入研究大气污染健康效应具有非常重要的意义。本文从以下四个方面对近年来国内外相关研究进行了归纳总结:(1)模拟体液、BCR、Tessier、Chester等逐级顺序提取方法被广泛用于重金属操作定义形态分析;(2)色谱-质谱联用技术和新型功能化材料用于重金属形态选择分析以及X射线吸收精细结构谱(XAFS)原位形态表征技术可以获取重金属价态、化合态、原子簇结构信息;(3)重金属形态粒径分布特征复杂,受多种因素影响,倾向于富集在细颗粒物中;(4)重金属形态时空分布具有很强的区域性,社会发展、工业来源、气候条件是主要影响因素,夏冬季节和雾霾天气危害性较大。     

利用代谢组学研究大气细颗粒物的生殖毒性效应

大气细颗粒物(PM2.5)污染已成为严峻的环境问题,探究PM2.5的毒性效应和机理变得尤为重要.本研究利用基于液相色谱/质谱的代谢组学技术,分析经PM2.5悬混液气管滴注暴露后成年雄性大鼠睾丸代谢组的全局变化,采用偏最小二乘判别分析法和非参数检验进行统计分析.结果表明,PM2.5暴露组大鼠睾丸的油提和水提代谢指纹谱均可与对照组实现准确区分,表明PM2.5暴露对大鼠睾丸的整体代谢网络产生了显著影响,最终鉴定出56个差异代谢物.通路分析显示,PM2.5暴露会引起大鼠睾丸的氨基酸和核苷酸代谢紊乱、类固醇激素代谢失衡以及脂类代谢异常,而这些重要通路可能是PM2.5生殖毒性的关键分子事件.     

Functional Properties and Molecular Degradation of Schizostachyum Brachycladum Bamboo Cellulose Nanofibre in PLA-Chitosan Bionanocomposites

The degradation and mechanical properties of potential polymeric materials used for green manufacturing are significant determinants. In this study, cellulose nanofibre was prepared from Schizostachyum brachycladum bamboo and used as reinforcement in the PLA/chitosan matrix using melt extrusion and compression moulding method. The cellulose nanofibre(CNF) was isolated using supercritical carbon dioxide and high-pressure homogenisation. The isolated CNF was characterised with transmission electron microscopy (TEM), FT-IR, zeta potential and particle size analysis. The mechanical, physical, and degradation properties of the resulting biocomposite were studied with moisture content, density, thickness swelling, tensile, flexural, scanning electron microscopy, thermogravimetry, and biodegradability analysis. The TEM, FT-IR, and particle size results showed successful isolation of cellulose nanofibre using this method. The result showed that the physical, mechanical, and degradation properties of PLA/chitosan/CNF biocomposite were significantly enhanced with cellulose nanofibre. The density, thickness swelling, and moisture content increased with the addition of CNF. Also, tensile strength and modulus; flexural strength and modulus increased; while the elongation reduced. The carbon residue from the thermal degradation and the glass transition temperature of the PLA/chitosan/CNF biocomposite was observed to increase with the addition of CNF. The result showed that the biocomposite has potential for green and sustainable industrial application.     

低浓度含铅细颗粒物暴露大鼠体内生物转运研究

食品接触性塑料制品、可再生资源、汽车尾气中含有低浓度铅。铅等重金属体内蓄积严重影响机体健康,但机体长期暴露于铅环境的代谢依然未知。以低剂量含铅细颗粒物暴露为场景,探讨其在大鼠体内的生物转运及体内分布。通过比较每日吸入染毒(7.05±0.83)μg/m~3及经口染毒0.42μg/d,连续染毒28d。结果显示含铅细颗粒物入血的速度比经口途径快,在肺内蓄积浓度达(4.2±0.67)μg/g,与经口染毒组比较有显著统计学差异(P0.01);排泄方面,吸入含铅细颗粒物以粪便、尿液形式排出为主,与经口染毒组比较具有体内蓄积量大、排泄慢、在股骨和肋骨内蓄积量大的特点。因此,吸入含铅细颗粒物暴露体内蓄积量大,代谢速度慢,暴露危害比经口途径更大。     

对岩体加固工程的水文地质条件分析

裂隙岩体的透水性各向异性和透水率大小的随机性,决定着渗控 (加固 )工程钻孔方位、倾角的多样性。它说明渗控工程设计中把裂隙岩体透水性假定成各向同性是不合实际的。应根据岩体的水文地质条件,寻找出裂隙隙宽、透水性和透水率相对较大的方位和倾角作为渗控工程钻孔的矢量。     

Transport of airborne particulate matters originating from Mentougou, Beijing, China

In this study, a coupled regional air quality modeling system is applied to investigate the time spatial variations in airborne particulate matters （PM10）, originating from Mentougou to Beijing municipal area in the period of April 1-7, 2004, and the influences of complex terrain and meteorological conditions upon boundary layer structure and PM10 concentration distributions. An intercomparison of the performance with CALPUFF against the observed data is presented and an examination of scatter plots is provided. The statistics show that the correlation coefficient and STD between the modeled and observed data are 0.86 and 0.03, respectively. Analysis of model results illustrates that the pollutants emitted from Mentougou can be transported to Beijing municipal area along certain transport pathways, and PM10 concentration distributions show heterogeneity characteristics. Contributions of the Mentougou sources to the PM10 concentrations in Beijing municipal area are up to 0.1-15 μg/m^3.     

钢筋混凝土圆形截面非均匀配筋的图算法

圆形截面是工程中常使用的截面形式之一,但圆形截面的配筋计算较为困难,存在双重非线性(材料和截面宽度变化的非线性),《混凝土结构设计规范》给出了计算均匀配筋的超越方程组,且须迭代求解,无法手算.另外,一些圆形截面构件(如桥墩、桩基的预制桩和灌注桩等)的截面尺寸大,构件长,钢筋用量大,若采用均匀布置的配筋方式,中性轴附近的钢筋应力小,强度利用率低,经济性差.若采用非均匀配筋,在远离中性轴的外围区域布置受力钢筋,可大幅节省钢筋用量,且能充分利用钢筋及混凝土的强度.为此本文通过应变计算应力,再计算出内力的方法推导计算圆形截面配筋的公式,并将计算结果绘制成了能计算配筋的无量纲诺模图,由此可快速手算配筋,该图通用性强,可用于任意直径大小及C50以下的混凝土强度等级,是一能快速计算配筋的实用工具.     

Influence of the Physical Nonlinearity of the Matrix on the Deformation of a Particulate Composite with Microdamageable Inclusions

The structural theory of short-term damage is generalized to particulate composites with nonlinearly elastic matrix and microdamageable inclusions. The basis for this generalization is the stochastic elasticity equations for a particulate composite with porous inclusions. Microvolumes of the material meet the Huber-Mises failure criterion. The damaged-microvolume balance equation and the equations relating macrostresses and macrostrains of a particulate composite with porous inclusions and physically nonlinear matrix constitute a closed-form system. This system describes the coupled processes of physically nonlinear deformation and microdamage. Algorithms for computing the microdamage-macrostrain relationships and deformation curves are proposed. Uniaxial tension curves are plotted for a particulate composite with linearly hardening matrix__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 4, pp. 3–11, April 2005.     

Short-term microdamage of a physically nonlinear particulate material under a combination of normal and tangential loads

The structural theory of short-term damage is generalized to the case where the undamaged components of a particulate composite deform nonlinearly under loads that induce a compound stress state. The basis for this generalization is the stochastic elasticity equations for a particulate composite with porous components whose skeletons deform nonlinearly. Damage in a microvolume of the material is assumed to occur in accordance with the Huber-Mises failure criterion. Balance equations for damaged microvolume are derived for the physically nonlinear materials of the components. Together with the macrostress-macrostrain relationship for a particulate composite with porous nonlinear components, they constitute a closed-form system of equations. This system describes the coupled processes of physically nonlinear deformation and microdamage. Algorithms for calculating the microdamage-macrostrain relationship and plotting stress-strain curves are proposed. Such curves are plotted for the case where the composite is subjected to a combination of normal and tangential loads, and microdamages occur in the linearly hardened matrix and do not in the linearly elastic inclusions. The stress-strain curves are examined depending on the volume fraction of inclusions and presence of tangential stresses __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 12, pp. 48–57, December, 2006.