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.     

二甲醚装置运行问题的原因分析及其解决措施

本文提出了贵州天福化工有限责任公司二甲醚装置运行中出现的问题,对其进行分析,提出解决问题的措施,并取得了较好的效果。     

New mesogenic compounds possessing a biphenyl ester and ether moiety comprising 1,3-dimethylbarbituric acid: synthesis,characterisation and mesomorphic studies

New substituted derivatives of 5-vinyl-1,3-dimethylbarbituric acid were synthesised and evaluated for liquid crystal properties. Two sets of molecules were prepared. One end of all the molecules possesses the 1,3-dimethylbarbituric core. The first set comprises biphenyl ethers, 4a–n and the second set biphenyl esters, 5a–g. Liquid crystalline properties were investigated by POM and DSC techniques. All the compounds exhibited enantiotropic smectic A and nematic mesophases. The LC properties were found to depend on the spacer and terminal alkoxy- chain and alkoxy- ester moiety of the molecules. Smaller alkyl chain members showed a smectic phase, while higher alkyl chain members showed a nematic phase.     

AlOOH在一氧化碳加氢反应中结构与性能的研究

采用沉淀水热法,通过调变水热过程中水与凝胶的质量比制备了不同的AlOOH,将其与工业甲醇催化剂C302混合形成复合催化剂,考察复合催化剂对一氧化碳加氢的影响,同时运用XRD、FT-IR、BET、NH_3-TPD-M S、TG-DTG和H_2-TPR等技术对不同AlOOH进行了表征。结果表明,水热过程中水与凝胶的质量比对AlOOH择优取向晶面、孔结构、表面酸强度等存在明显影响,进而导致复合催化剂产物中出现分布不同的低碳醇或二甲醚。其中,当水和凝胶的质量比为2∶1时,AlOOH的(020)和(120)晶面择优取向,孔容增大,且其表面具有适宜的强弱酸比例中心,复合催化剂呈现出较高的低碳醇选择性,表明AlOOH具有碳链增长的作用,这为合成气制取低碳醇催化剂提供了新的思路。     

Efficient Synthesis of Dimethyl Ether from Methanol in a Bifunctional Zeolite Membrane Reactor

A sandwich FAU–LTA zeolite dual‐layer membrane has been developed and used as a catalytic membrane reactor for the synthesis of dimethyl ether (DME). In the top H‐FAU layer with mild acidity, methanol is dehydrated to DME. The other reaction product, water, is removed in situ through a hydrophilic Na‐LTA layer, which is located between the porous alumina support and the H‐FAU top layer. The combination of mild acidity with the continuous removal of water results in high methanol conversion (90.9 % at 310 °C) and essentially 100 % DME selectivity. Furthermore, owing to the selective and continuous removal of water through the Na‐LTA membrane, catalyst deactivation can be effectively suppressed.     

3-硫代甲酰基中氮茚与三丁基膦的反应

2-Phenyl-3-thioformylindolizine and 1,2-dimethyl-3-thioformylindolizine undergo a novel desulfur coupling reaction in the presence of tributylphosphine to give （E）-1,2-bis（3-indolizinyl）ethenes in high yields. The structures of products were confirmed by IR, ^1H NMR, MS, elemental analysis and single crystal X-ray diffraction analysis. The mechanisms involved in various stages of the reaction were discussed.     

逐步法合成杯[4]芳烃关环反应的改进

对位带有3种或4种不同取代基的杯「4］芳烃一般通过逐步合成法合成．50年代后期,wS和Hllfl比rI'·'a就用［1十1十1十工］的逐步法9步合成出了杯［4］芳烃,总产率相当低·1979年B6hmer等［'·'报道用对位取代酚的线型三聚体与2,6一双溪甲基对取代酚在乙酸中进行关环反应合成杯［4」芳烃,这种［3＋l」的逐步法只需3步连续反应就能合成带有3种不同取代基的杯卜」芳烃,但最后。步关环产率仍然很低（2％、15％）［"．后来＊dhmeTD'等将关环反应改进为在TICI。／二氧六环体系中进行,产率有所提高,这种逐步法曾用于不对称杯［4」芳烃的…     

从超临界二氧化碳和甲醇直接合成碳酸二甲酯

Dimethyl carbonate (DMC), an environmentally benign intermediate for organic synthesis, has been mainly synthesized through non-phosgene route of oxidative carbonylation[1]. Direct synthesis of DMC from carbon dioxide and methanol is of more significance due to atom economy. Organometallic compounds of formulae R2M(OR)2, M(OR)2 or M(OR)4[2,3] were employed as catalysts in direct synthesis of DMC, where an activation mechanism of CO2 insertion into metal-oxygen bond was supposed. Unfortunately, the yield of DMC was low even in the presence of chemical dehydrants because mainly of thermodynamic limit.     

5-磺酸钠间苯二甲酸二甲酯的高效液相色谱法分析

提出了用离子对反相高效液相色谱分析５－磺酸钠间苯二甲酸二甲酯的方法,色谱柱为ＨｙｐｅｒｓｉｌＢＤＳＣ１８,５μｍ,２５０ｍｍ×４．６ｍｍ,流动相为Ｖ（甲醇）∶Ｖ（水）＝６０∶４０（甲醇中含四丁基磷酸二氢铵１０ｍｍｏｌ／Ｌ）,柱温为３０℃,流速为０．８ｍＬ／ｍｉｎ,进样体积为２０μＬ,检测波长为２２０ｎｍ。用外标法进行了定量,相对标准偏差和回收率分别为０．２６％和９８．１％～９９．６％。     

制鞋业"三苯"废气治理

采用ＹＪＴ组合净化装置对制鞋厂生产中的“三苯”废气进行吸收治理,净化效率大于９３％,经处理后气体中的“三苯”浓度均达到了ＤＢ３５／１５６－１９９６《制鞋工业大气污染物排放标准》中的一级标准．