Speciation of alkyllead and inorganic lead by derivatization with deuterium-labeled sodium tetraethylborate and SPME-GC/MS

A method for full speciation and determination of alkyllead and inorganic lead(II) in aqueous samples was developed. This was accomplished by in situ derivatization with deuterium-labeled sodium tetraethylborate NaB(C2D5)4 (DSTEB). The derivatization was carried out directly in the aqueous sample and the derivatives were extracted from the headspace by a solid-phase microextraction (SPME) fiber. The extracted analytes were then transferred to a GC/MS or a GC/FID for separation and detection. The research presented demonstrates that SPME and the derivatization reagent DSTEB can be used successfully for the speciation of Pb2+, Pb(CH3)3+, Pb(C2H5)3+, and Pb(C2H5)4 in water samples. All derivatives, Pb(C2D5)4, (CH3)3Pb(C2D5), (C2H5)3Pb(C2D5), and Pb(C2H5)4, are separated using an SBP-5 column. This method was applied to monitor degradation of tetraethyllead in water. This is the first report of ethylation by DSTEB for full speciation of methyllead, ethyllead, and inorganic lead compounds. This approach can be extended to other organometallic compounds as demonstrated for ethyltin speciation. This full speciation method will aid in monitoring occurrence, pathways, toxicity, and biological effects of these compounds in the environment. It is easily adopted for field analysis.     

Effect of rapid quenching and with Carbon and Nitrogen on the structure and superconducting properties of the Nb3Ge compound

The effect of rapid quenching and alloying with carbon and nitrogen on the superconducting properties of the Nb3Ge compound has been studied. The quantitative phase X-ray analysis of the studied specimens depending on the content of alloying components has been carried out. The temperature at which the transition into the superconducting state occurs as well the parameters of the alloy lattices have been investigated.     

Thermomechanical Analysis of (Cu0.5Tl0.5)-1223 Substituted by Pr and La

The thermomechanical analysis (TMA) of Cu 0.5 Tl 0.5 Ba 2 Ca 2 x R x Cu 3 O 10 δ,where R=Pr and La,with 0.0≤x≤0.15,was carried out in temperature range from 450 to 1145 K.The samples were prepared by singlestep solid state reaction technique.The prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The superconductivity of the prepared samples was investigated by electrical resistivity measurement.The results showed that low substitution content enhanced the (Cu 0.5 Tl 0.5)1223 phase formation,while the higher substitution content degraded this phase.The higher superconducting transition temperatures T c were found to be 114 K and 109 K at x= 0.025 for Pr-and La-substitutions,respectively.The average linear thermal expansion coefficient increased as x increased,while the shrinkage temperature decreased as x increased.Those results were emphasized by porosity and Vickers microhardness calculations.Debye temperature θ D was calculated from the linear thermal expansion coefficient data and correlated to T c to estimate the electron-phonon coupling λ ep.     

Effects of Nitrogen Dioxide and Carbon Monoxide on the Determination of Sulfur Dioxide by Flue Gas Analyzer

Reference materials of SO₂, NO₂ and CO were used to study the effects of different concentrations of NO₂ and CO on the determination value of SO₂ by flue gas analyzer with electrochemical sensors and UV differential optical absorption spectroscopy (DOAS). Results showed that SO₂ was affected more greatly by NO₂ than CO using the method of electrochemical sensors. The electrolytic reaction of NO₂ was the primary factor causing the lowerconcentration of SO₂. SO₂ with the concentration of 0–300 mg/m³ was affected greatly by NO₂, and the determination value was unreliable. The determination error of SO₂, with the concentration higher than 1500 mg/m³, was about 2%, and the test value was more accurate. The method of UV DOAS could improve the determination reliability of concentration of SO₂ greatly when NO₂ coexisted.     

高压氢去除钒表面碳、氮、氧杂质的热力学分析

基于钒的相关相图,分析了钒表面钒的碳化物、氮化物和氧化物可能存在的形式。采用热力学方法计算了高温和高压条件下氢与钒碳化物、钒氮化物和钒氧化物的吉布斯自由能变,分析了高压氢去除上述杂质的可能性。计算结果表明,100MRa条件下钒表面的碳化物杂质转化为甲烷需要860K以上的温度;50MPa、低于1000K温度氢不能有效去除金属钒表面所有价态的钒氧化物;50MPa、298～1000K温度高压氢不能有效去除钒的氮化物。     

Isotope 18O/16O ratio measurements of water vapor by use of the 950-nm wavelength region with cavity ring-down and photoacoustic spectroscopic techniques

Two optical methods, cavity ring-down spectroscopy and photoacoustic spectroscopy, are applied to the measurement of the isotope ratio 18O/16O in water-vapor samples with a Nd3+:YAG pumped-dye laser. The combination band of (2v1 + v3) in the 960-nm region of water molecules is investigated for two standard water samples, the Vienna Standard Mean Ocean Water and the Standard Light Antarctic Precipitation. The results demonstrate that the two methods have the potential of compact systems for in-situ measurements of H2O isotope ratio in the environment.     

不锈钢纤维(SSF)和镍碳复合纤维(NCF)填充PC/ABS导电塑料性能影响分析

本文介绍了采用不锈钢纤维(SSF)和镍碳复合纤维(NCF)填充PC/ABS注塑成型新型轻质复合导电塑料,着重阐述了填充纤维后对复合材料的屏蔽效能、力学性能等的影响。     

壳聚糖/PHB复合缓释微包囊的制备与体外释药评价

用疏水性聚酯PHB外包覆壳聚糖-三聚磷酸钠-阿斯匹林药物缓释体(CPA)制备了壳聚糖/PHB复合缓释微包囊(CPAB),以克服CPA遇酸不稳定的释药特点.用傅立叶红外分光光度计、激光粒度仪、扫描电镜表征了CPAB的组成、粒径及表面形貌.结果显示,CPAB粒径在50～100nm和载药率18.5%时,表面有不均匀的空隙.体外释药评价证实CPAB能有效解决CPA在酸性下的不稳定性,具有长效缓释作用.     

GC/MS法结合保留指数分析留兰香油成分

利用GC/MS结合保留指数分析留兰香油成分,并用峰面积归一化法计算各组分相对含量。分析并确定33个化合物,占留兰香油成分97.53%,其主要成分为香芹酮(56.19%),柠檬烯(21.26%),α-松油醇(4.81%),薄荷酮(2.12%),(Z)-二氢香芹酮(2.01%),芳樟醇(1.42%),β-蒎烯(1.46%),α-蒎烯(1.16%),3-辛醇(0.84%),莰烯(0.83%),月桂烯(0.69%)等。采用保留指数来鉴别同系物及同分异构体,提高对留兰香油成分定性准确性,研究结果可为留兰香油产品开发和应用提供理论依据。     

NiO_x与活性炭协效催化聚丙烯成炭及燃烧性能

利用不同价态的镍的氧化物(Ni Ox)为脱氢催化剂,活性炭(AC)为成炭促进剂,制备出了高效成炭阻燃材料,并研究了Ni的价态和AC含量及配比对聚丙烯(PP)催化成炭中PP自身成炭的影响。实验结果表明,Ni O与AC协同具有显著的催化成炭效果,其成炭率最高可达到32.3%;热释放速率(HRR)、质量损失速率(MLR)、热重分析表明PP/NiO/AC复合材料的HRR、MLR等燃烧特征参数均有所降低,具有较明显的阻燃性能和热稳定性;扫描电镜、高倍扫描电镜、透射电镜显示成炭结构为稳定的多壁碳纳米管(CNTs);X射线衍射结果表明NiO_x高温下还原成金属Ni,Ni作为活性中心催化PP脱氢裂解。     

碳毡及编织结构碳/碳复合材料常温力学性能研究

为研究两种不同预制体增强的碳/碳(C/C)复合材料的损伤破坏机制差别,将为该材料应用于结构件提供依据,对碳毡及2.5D编织结构增强的C/C复合材料的常温弯曲、剪切、压缩性能进行了测试,并用扫描电镜观察其断面形貌,对C/C复合材料在静态载荷下的力学性能及损伤破坏行为进行研究,探讨有关因素对材料性能和损伤破坏的影响.研究结果表明:两种不同增强体的C/C复合材料的断裂机理存在很大差异,且密度对C/C复合材料的常温力学性能有较大的影响.     

厦门港和筼筜湖沉积物中多溴联苯醚类防火剂(PBDEs)的色谱一质谱联机同位素稀释法测定

利用13C标记的多溴联苯醚标准作内标对厦门沿岸海域和筼筜湖沉积物进行色谱—质谱联机测定并采用同位素稀释法进行数据收集和计算,分别测定PBDE3、15、28、47、60、85、99、100、138、153、154和183共12个同类化合物,其回收率范围为75.8-100.5%,最低检测限0.02ng/g(d),沉积物中总PBDE最高值为厦门第一码头2.06ng/g(d),最低是厦门大学海水浴场为0.10ng/g(d)。     

厦门港和筼筜湖沉积物中多溴联苯醚类防火剂(PBDEs)的色谱-质谱联机同位素稀释法测定

利用^13C标记的多溴联苯醚标准作内标对厦门沿岸海域和筼筜湖沉积物进行色谱-质谱联机测定并采用同位索稀释法进行数据收集和计算,分别测定PBDE3、15、28、47、60、85、99、100、138、153、154和183共12个同类化合物,其回收率范围为75．8—100．5％,最低检测限0．02ng／g（d）,沉积物中总PBDE最高值为厦门第一码头2．06ng／g（d）,最低是厦门大学海水浴场为0．10ng／g（d）。     

用火花源原子发射光谱法测定普碳钢中碳、硅、锰、磷、硫含量的不确定度的评定

火花源原子发射光谱法测定普碳钢中碳、硅、锰、磷、硫含量，依据JJG1059—1999对测量结果的不确定度进行了评定和表述，分析了影响测量不确定度的各个因素，对各个分量进行了计算和合成。