Topical Problems in Elemental Analysis of Advanced Ceramic Materials

Selected prominent problems in the analysis of advanced ceramic materials are surveyed. The importance of reliability of results is discussed in the field of elemental trace- and microanalysis in view of its interaction with economy, power of detection, local resolution and speciation selectivity. Particular problems in the analysis of major constituents, trace components and microlocal distributions are based on the striking propertics of ceramics; they are exemplified. Analytical assistance must start from the beginning of the production processing, in the preparation of the powdered base materials. Determination of the stoichiometry requires high accuracy and differentiation of chemical species in bulk and surface analysis of ceramic base powders. Element trace determination by direct instrumental methods requires standard reference materials for calibration; these are currently inavailable in a sufficient variety. For optimum reliability and power of detection, element traces must be prepared in isolated form in a small excitation volume for analysis. A review on the state-of-the-art of wet-chemical combined procedures is presented. Decomposition position procedures are emphasized, due to their risk of contributing severe systematic error. Combustion in elementary fluorine is presented for decomposition of refractory materials. The performance of some direct procedures is discussed. Very efficient methods are available for element trace determinations in ceramic materials, offering high detection power. Several approaches for high-resolution local microanalysis in non-conductive ceramic materials are identified as the most promising development in the analysis of sintered compact ceramic products and devices.     

A brief introduction to neutron activation analysis in China

The history, the major achievements in both methodology and applications, the current trends and future perspectives of neutron activation analysis (NAA) in China are briefly described.     

IBA和NAA对海桐水培的影响

试验选取一年生的海桐健壮枝条作为水培插条,分别用浓度为50、100、200 mg/L的IBA、NAA对海桐枝条进行处理,探讨海桐水培生根最适合的植物生长调节剂及其最佳浓度。结果表明:IBA 50、200 mg/L,NAA 50、200 mg/L的处理对海桐水培生根率均有促进作用,其中IBA 50 mg/L、NAA 200 mg/L的促进作用最为明显,且在该浓度下使海桐提前24 d生根。仅NAA 50 mg/L的处理对海桐水培的发芽有显著促进作用,其他浓度的NAA及各浓度的IBA则对海桐的发芽率无显著影响。IBA 50 mg/L、NAA 50 mg/L对海桐的不定根生长(数量)也有显著促进作用。     

山楂苗木根系药剂处理的生理效应

用α—萘胺法、纸层析法和比色法对NAA处理的山楂苗木根系活力、氨基酸种类和含量分别进行了测定;同时用垂直板型聚丙烯酰胺凝胶电泳法对山楂叶和根内的过氧化物同工酶的酶谱进行了分析。结果表明,NAA处理能增加根内氨基酸种类和含量,也提高了根系活力。10mg·kg~(-1)NAA处理对根和叶内过氧化物同工酶的酶带和酶量均有影响,而5mg·kg~(-1)处理的与对照类似。     

陕西段家坡黄土剖面沉积界线铱的赋存状态及其对N/Q地外撞击事件的启示

采用悬浮沉降法对陕西段家坡黄土剖面第三系—第四系界线样品进行了粒级分选，然后用中子活化分析方法测定了铱和其他微量元素在不同粒级中的含量。实验结果显示，铱在不同粒级物质中的含量按以下顺序增加：粗粉砂（３０～１０５μｍ）＜砂粒（＞１０５μｍ）＜细粉砂（２～３０μｍ）＜粘土（＜２μｍ）。在粘土颗粒物质中，铱的最高含量达８５６ｐｇ／ｇ，较全岩样品富集约１５倍。除了金之外，其他元素（包括Ａｓ、Ｓｂ、Ｂｉ等亲硫元素）在不同粒级中的分布形式与铱显著不同。很显然，铱和其他元素有着不同的来源，界线黄土中铱的异常富集不可能由火山活动或者表生地球化学作用所形成，而极有可能和上新世末（２．４ＭａＢＰ）发生在南太平洋的地外撞击事件有关。这一实验结果表明，南太平洋Ｎ／Ｑ地外物体撞击事件产生的爆炸尘埃可能扩散到了北半球。作为一种近似，以黄土剖面Ｎ／Ｑ界线附近铱的剩余通量作为全球平均，可以估计该撞击物体相当于一直径为２．６ｋｍ的Ｃ１型碳质球粒陨石球体。如此巨大的陨石与地球相撞足以诱发全球性的气候灾变效应     

Neutron activation analysis and M(o)ssbauer spectroscopy research on coloring mechanism of ancient Chinese Guan porcelain

The content of 30 kinds of coloring elements in Guan porcelain in the Southern Song Dynasty has been determined by neutron activation analysis (NAA). Iron is the major coloring element. M(o)ssbauer spectroscopy has shown that the iron of the glaze exists in the form of structural iron (Fe2+, Fe3+). The quantitative relationship between the main wavelength of every color glaze and the relative content (Fe2+/Fe3+) of structural iron has been determined. Thus the coloring mechanism of Guan porcelain in the Southern Song Dynasty has been revealed entirely.     

Fractionation analysis of iodine in bovine milk by preconcentration neutron activation analysis

Iodine is an essential trace element for human beings. The main source of iodine is generally food items such as fish and milk. Either the lack or the excess of iodine can cause health problems. There exists an increasing interest in the determination of total iodine as well as various species of iodine in milk. We have developed an epithermal neutron activation analysis method with a Compton suppression (ENAA-CS) counting system for the determination of ng mL⁻¹ levels of iodine. We have also employed chemical separation methods prior to ENAA-CS to measure the fraction-specific concentrations of iodine in bovine milk. We have measured the following iodine concentrations in homogenized milk (3.25%milk fat): 0.48 ± 0.02 μg mL⁻¹ of total iodine, 0.020 ± 0.003 μg mL⁻¹ of lipid-bound iodine, 0.039 ± 0.002, 0.019 ± 0.002 and 0.021 ± 0.004 μg mL⁻¹ of protein-bound iodine depending on the protein separation method and 0.45 ± 0.02 μg mL⁻¹ of inorganic species.     

Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples

The radiometric methods, alpha (α)-, beta (β)-, gamma (γ)-spectrometry, and mass spectrometric methods, inductively coupled plasma mass spectrometry, accelerator mass spectrometry, thermal ionization mass spectrometry, resonance ionization mass spectrometry, secondary ion mass spectrometry, and glow discharge mass spectrometry are reviewed for the determination of radionuclides. These methods are critically compared for the determination of long-lived radionuclides important for radiation protection, decommissioning of nuclear facilities, repository of nuclear waste, tracer application in the environmental and biological researches, these radionuclides include ³H, ¹⁴C, ³⁶Cl, ⁴¹Ca, ^59,63Ni, ^89,90Sr, ⁹⁹Tc, ¹²⁹I, ^135,137Cs, ²¹⁰Pb, ^226,228Ra, ²³⁷Np, ²⁴¹Am, and isotopes of thorium, uranium and plutonium. The application of on-line methods (flow injection/sequential injection) for separation of radionuclides and automated determination of radionuclides is also discussed.     

电感耦合等离子体质谱、中子活化分析及其它谱学方法测定环境、生物样品中铝形态和含量研究进展

本文综述了上世纪90年代以来电感耦合高频等离子体质谱(ICP-MS)、中子活化分析(NAA)以及其它谱学方法测定环境生物样品中铝形态的研究进展,共引用文献60篇。     

NAA处理下南林895杨无菌苗茎中糖含量 及其相关酶活性的变化

不同浓度NAA处理下,对南林895杨无菌苗茎中糖含量及其相关酶活性的变化进行了测定和分析。结 果表明：(1)100 mg/L的NAA增加了南林895杨无菌苗茎中蔗糖、果糖的含量,提高了酸性转化酶(AI)、中性 转化酶(NI)的活性,降低了蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)的活性,而高浓度NAA的作用效果正相 反;(2)NAA处理下,茎中蔗糖、果糖含量均与AI活性显著正相关,蔗糖含量与SPS、SS活性极显著负相关, 而果糖与之相关性不显著。可见,适宜浓度的NAA对南林895杨无菌苗茎的糖代谢过程具有一定的促进作用 。