Carbon fiber/epoxy composite materials cured thermally and with microwave irradiation

In this paper, composite materials of short carbon fibers (CFs) and a thermosetting epoxy were prepared in three different ways: without curing, thermal curing, and thermal curing followed by microwave irradiation. Mechanical properties of the three kinds of CF reinforced plastic (CFRP) composites were studied to explore the effect of microwave irradiation. Microscopic study with the aid of a scanning electron microscope (SEM) was performed on fractured composite surfaces to identify the principle features of failure. Degree of polymerization of the epoxy resin in the three CFRP composites was evaluated by infrared (IR) spectroscopy. The microwave irradiated CFRP exhibited mechanically ductile behavior even though its highest degree of polymerization. Use of microwaves and resultant stronger physico-chemical linkage at the interface between CF and epoxy resin are the main feature of this study.     

国标测定土壤中铅测定方法改进的探讨

为改进测定土壤中铅的石墨炉原子吸收法,通过湿法消解,应用基体改进剂磷酸二氢铵,提高方法的准确度和精密度.结果表明,方法的线性范围为0.0 ～ 50.0 μg/L,检出限为0.21mg/kg,回收率为82.6％～94.4％,该方法具有干扰因素少,灵敏度高、准确的特点,可推广应用.     

微波消解-电感耦合等离子体质谱法检测土壤中16种稀土元素

建立了微波消解-电感耦合等离子体质谱法(ICP-MS)测定土壤样品中16种稀土元素的分析方法。样品经硝酸-过氧化氢-氢氟酸消解,直接用ICP-MS测定试液中16种稀土元素。研究了ng/mL水平的Ba氧化物及轻稀土氧化物对重稀土元素的干扰程度,其中Ba和Pr的氧化物干扰较严重,不过此类干扰可通过Method编辑干扰方程得以校正。测定土壤标准物质GBW07446及GBW07451,结果与标准物质证书值一致。     

Screening Procedure for Sodium Fluoroacetate (Compound 1080) at Sub-microgram/gram Concentrations in Soils

Abstract

Sodium fluoroacetate (Compound 1080) is readily quantitated at sub-microgram per gram concentrations in small (ca. 1 g) soil samples. Samples are ultrasonically extracted with water, which is then partitioned with hexane, and acidified prior to re-extraction with ethyl acetate. The latter is taken to dryness in the presence of triethanolamine “keeper”, and the resulting acid is derivatized with pentafluorobenzyl bromide. Quantitation is performed using a gas chromatograph equipped with an electron-capture detector. A standardized statistical protocol is used to validate a screening level of 0.2 μg Compound 1080/g soil. Difluoroacetic, trifluoroacetic, and naturally-occurring formic acids do not interfere with the determination. The recovery for Compound 1080 was 40% from soil fortified to 0.2 μg/g soil.     

镉污染土壤的植物修复

Cd在土壤中有稳定、积累和不易消除的特点,且可通过食物链富集使人体产生慢性中毒。我国农村镉污染尤其严重。植物修复技术是优秀的土壤镉污染治理技术,近两年来成为研究热点。本文阐述了土壤镉污染植物修复技术的机理、具体做法和技术进展。     

成都市三环地区地基土壤氡含量测量

对成都市三环地区地基土壤中氡含量进行了检测,掌握了区域性氡含量的分布状况,探讨了整个成都市待建地坪基础中的放射性水平,并佐以对成都市地质构造的浅析,为今后城市化进程中的新建、扩建建筑的地下防氡设计提供依据,以最终提升市民的生活环境质量。     

贵州凤冈县宜茶区土壤重金属含量状况及污染评价

对贵州凤冈县14个乡镇的宜茶土壤中汞、镉、铅、砷、铬、铜6种重金属含量进行统计分析,根据NY/T 5020-2001《无公害食品茶叶产地环境条件》、NY 5199-2002《有机茶产地环境条件》、NY/T 5295-2004《无公害食品产地环境评价准则》进行评价,为凤冈县茶园建设规划提供理论依据。     

钢筋混凝土平面杆件非线性分析模型及其应用

本文提出了五区段变刚度单元模型,连续五区段变刚度单元模型,并将其应用于钢筋混凝土平面高层结构的非线性地震反应计算。     

A two-phase elastoplastic model for unidirectionally-reinforced materials

A complete analytical formulation for the elastoplastic behaviour of a composite material comprising one single array of reinforcing inclusions perfectly bonded to the matrix is developed in this paper. Fundamental relationships establish the link between the total stress and strain variables, and those pertaining to the individual constituents (matrix and reinforcement) regarded as superposed continuous phases. Assuming that each constituent behaves as an elastic perfectly plastic material, the constitutive equations governing the evolution of the reinforced material as a whole are derived. They reveal a hardening phenomenon arising from the non-compatibility between matrix and reinforcement plastic strains. It is shown in particular that the obtained constitutive law falls within the formalism of generalized standard plasticity: the reinforcement residual stress plays the role of a hardening parameter which controls the evolution of the yield surface, while the associated kinematic variable is the plastic strain discrepancy between matrix and reinforcement phases.Owing to its inherent simplicity, the model is easily amenable to a numerical treatment for structural analysis. It is shown in particular how the classical iterative algorithm can be modified accordingly, and an illustrative application is finally presented in the field of civil engineering.     

纤维金属层极疲劳寿命预测的研究进展

简要介绍了纤维金属展板的起源、性能特点、应用现状与前景,对其疲劳损伤机理作了简要分析．对影响层板疲劳寿命的两个关键因素──桥接应力与分层扩展从理论分析与测量技术两方面结合自己的研究成果作了系统评析．详细分析了层板在等幅疲劳下寿命预测的研究现状．介绍了层板在变幅载荷下的疲劳行为（包括裂纹扩展与分层扩展）与寿命预测的研究进展,指出了目前预测模型的有待改进的建议．