产母及新生儿血铅水平及影响因素的研究

为了解佛山市产母、新生儿血铅水平及其相关影响因素 ,采用电感耦合高频等离子体发射光谱法 ,于 2 0 0 2年 5～ 9月 ,取本院产科产母静脉血及其新生儿脐血 1 5 2例 ,进行血铅、钙、锌、铁、铜和锰水平测定 ,按妇幼保健管理卡内容 ,进行相关记录。结果表明 ,产母血铅水平90 1± 3 4 8μg/L ,BPb≥ 1 0 0 μg/L者占 2 0 3 9% ;新生儿脐血铅水平 89 2± 3 1 6μg/L ,铅中毒率为2 2 3 7% ;母子血铅值呈显著正相关 (r=0 85 7,P <0 0 1 ) ,产母血铅值与其血钙、铁值显著负相关 (r=0 2 66,-0 3 0 1 ,P <0 0 5 ) ;城郊产母及新生儿血铅水平显著高于城区。揭示市郊孕妇、新生儿血铅较高 ,血钙、锌、铁含量影响血铅水平     

半化学法制备Pb(Fe2/3W1/3)O3陶瓷粉体的反应机理

铅系弛豫铁电陶瓷钨铁酸铅Pb(Fe2/3W1/3)O3(PFW)是一种重要的介电材料,具有较大的介电常数(8000)和较低的烧结温度(小于900℃),适用于制备低烧高介的多层陶瓷电容器犤1～4犦。在传统氧化物法合成PFW的过程中,易生成恶化介电性能的钨酸铅(PbWO4或Pb2WO5)或焦绿石相(Pb2FeWO6)等其他相犤3,4犦。尽管通过加入过量5%的Fe2O3可以消除这些其他相,但因含较多的变价铁离子(Fe3+和Fe2+)而产生介电老化的缺点犤5犦。虽然二次合成法被广泛用于制备铅系弛豫铁电陶瓷犤6犦,但对制备PFW陶瓷的效果并不明显,仍有少量的钨酸铅PbWO4存在,并且预烧…     

Direct anodic oxidation ofp-methoxytoluene in methanol. The effect of electrolysis conditions

The effect of anions of the supporting electrolyte (F^–, dialkylphosphate, TsO^–, and BF ₄ ^– and other electrolysis conditions (anode material, temperature, substrate concentration) on the selectivity of the direct anodic oxidation ofp-methoxytoluene in methanol into 4-methoxybenzaldehyde dimethylacetal was studied. The highest selectivity was obtained in the presence of fluoride anion.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 524–527, March, 1995.This work was financially supported by the Ministry of Science, High School and Technical Policy of the Russian Federation within the scope of the State scientific-technical program Ecologically harmless processes of chemistry and chemical technology (project No. 1.140 Low-tonnage chemical products) and by the International Science Foundation (Grant Ch-2-1246-0923).     

THE ADSORPTION OF OXYGEN OVER ThO_2-BaF_2 CATALYST

IntroductionInthcsclcctivcoxidationofalkanes.suchas'theoxidativccouplingofmcthanc(0CM)andthcoxidativcdch}'drogenationofcthanc(0DE)t0prcparccth}'lene.bothoxidcionsofthelatticeandtheox}'genspeciesovercataIystsuffocepla}'animportantrole.Althoughcxtcnsivcinvcstigationshavcbeengivcntothecharactcrizationofox}'gcnspccicsandthcreactionofox}'gcnspecicsx`ithalkanes,itisstilldifficulttosayt`hichoncsofox}'gcnspcciesarcthcactivcspecicsinthcactivation0falkancs.bccauscthenaturcofcatal}'stsandthecxperimcntc…     

Thermal Analysis of Hexachloroplumbate and Chlorides Containing Complex Divalent Lead 2,2'-bipyridine Cations

Lead(II) 2,2'-bipyridine hexachloroplumba tetetrahydrate was synthesized and investigated by DTA, TG and DTG. IR spectroscopy and other methods enabled the identification of some of the decomposition products. Comparative studies on the corresponding chlorides: [Pb(bipy)]Cl₂ and [Pb(bipy)₃]Cl₂, which can be considered as precursors of the hexachloroplumbate, were also undertaken. X-ray measurements enabled the tentative determination of the crystal structure of [Pb(bipy)]Cl₂. Hexachloroplumbate decomposes with the liberation of chlorine, water and organic ligands, and the process is accompanied by the simultaneous transition of Pb(IV)→Pb(II). Chlorides release only ligands upon heating. Residues comprised always PbCl₂. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation and properties of rare-earth containing oxide fluoride glasses

The preparation of the rare earth containing oxide fluoride glasses LnF₃ (Ln; Y through Lu)-BaF₂-AlF₃-GeO₂ in which the nominal content of LnF₃ reached 60 mol% in maximum and their basic properties such as density, refractive index and glass transition temperature were investigated and summarized in detail. Especially, in order to discuss the local structure around the rare earth ion in the glass, the Judd-Ofelt analysis (discussion with Ω parameters) of the HoF₃-BaF₂-AlF₃-GeO₂ glasses was carried out. The unique fluorescent behavior and the magnetic properties of LnF₃-BaF₂-AlF₃-GeO₂ glasses (Ln = Tb and/or Sm) were also studied.     

Development of direct fluorination technology for application to materials for lithium battery

Direct fluorination of 1,3-dioxolan-2-one with elemental fluorine was successfully carried out to provide 4-fluoro-1,3-dioxolan-2-one, which was expected as an additive for lithium ion secondary battery. 4-Fluoro-1,3-dioxolan-2-one was also further fluorinated with elemental fluorine to give three isomers of difluoro derivatives by the same methodology. Another topic is the preparation of trifluoromethanesulfonyl fluoride, an intermediate of lithium battery electrolyte, by the reaction of methanesulfonyl fluoride with elemental fluorine. The use of perfluoro-2-methylpentane as a solvent gave satisfactory selectivity of trifluoromethanesulfonyl fluoride.     

The ordered phase of methylammonium lead chloride CH3ND3PbCl3

The perovskite-structured compound methylammonium lead chloride orders into a low-temperature phase of space group Pnma, in which at 80 K each of the orthorhombic axes , and is doubled with respect to the room temperature disordered cubic phase (). The structure was solved by ab initio methods using the programs EXPO and FOX. This unusual cell basis for space group Pnma is not that of a standard tilt system. This phase, in which the methylammonium ions, are ordered shows distorted octahedra. The octahedra possess a bond angle variance of 60.663°² and a quadratic elongation of 1.018, and are more distorted than those in the ordered phase of methylammonium lead bromide. There is also an alternating long and short Pb-Cl bond along a, due to an off-center displacement of Pb within the octahedron. This suggests that the most rigid unit is actually the methylammonium cation, rather than the PbCl₆ octahedra, in agreement with existing spectroscopic data.     

Determination of fluoride in complex liquid matrices by electrothermal atomic absorption spectrometry with in-furnace oxygen-assisted ashing

A new chemical method is reported for the determination of total fluoride in complex liquids and suspensions, such as fruit juices, urine, serum and blood. It is based on the formation of the A1F radical in a graphite furnace afterin situ oxygen-assisted ashing of the untreated sample. The absorbance of this radical is measured at 227.45 nm. The method is relatively easy to use and provides a low detection limit (14 ng/ml) and reasonable reproducibility (5–10%).