世界上第一个物理技术研究所的建立及其影响

德国夏洛滕堡物理技术研究所（The Physikallisch-Technische Reichanstalt,简称PTR）是世界上第一个国家级的物理技术研究所，它开创了科学研究和技术研究相结合，服务于工业和国家经济之先河。文章从PTR建立的历史背景、早期研究工作和所产生的影响等方面作较为全面的讨论。     

Critical evaluation of gas standards based on hydrogen

Summary Six commercial hydrogen standards containing helium, oxygen, nitrogen, methane and carbon dioxide at trace levels were analyzed by gas chromatography, for periods up to 105 days. The concentrations, in the range of 0–120 μmol mol⁻¹, were stable (with the exception of oxygen) but often significantly different from the certified values provided by the suppliers, especially for helium, oxygen and nitrogen. Concurrently, some experiments were carried out to verify the stability of gas mixtures based on hydrogen stored in cylinders submitted to different chemical and physical treatments. The causes that led to the deviations observed, as well as the decreases in oxygen, are discussed. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996.     

Characterization of high-temperature superconductors by electron microprobe analysis

In order to optimize the physical properties of HTSC small single crystals grown from a melt for basic studies of their physical properties the influence of the environment on their impurity content was investigated by EPMA. This requires quantitative analysis of all elements being present in the crystals. The accuracy of results was affected by problems with the choice and quality of standards, by contamination but also by malfunction of microprobe electronics. The HTSC materials were found to react with mills, milling balls, crucibles and the atmosphere. These problems are being discussed and some reactions being studied for Y₁Ba₂Cu₃O_6+x (0 < x < 1) HTSC in A1₂O₃ and ZrO₂ crucibles. The crystals grown contain reproducible amounts of impurities depending on boundary conditions and exhibit a zone structure in composition particularly for Y and Ba within their range of homogeneity.     

高分辨等离子体质谱法直接测定高纯镓中的痕量元素

建立高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定高纯镓样品中Be、Mg、A l、S i、Ti、V、Cr、Mn、Fe、Co、N i、Cu、Zn、Ge、As、Mo、Ag、Cd、In、Sb、Ba、Pb、B i等痕量元素的方法。样品用HNO3 HC l经微波消解后,试液直接进样用HR-ICP-MS法同时测定上述元素,在高分辨质谱测量模式下避免了大量的质谱干扰,详细地研究了HC l和高纯镓所产生的基体效应,以Sc、Rh、Tl作为内标元素校正了基体效应,讨论和确定了实验的最佳测定条件。结果表明,23种痕量元素的检出限在0.001~0.21μg/L之间;回收率在89.8%~111.6%之间,相对标准偏差(RSD)小于3.3%。     

Rearrangements of the carbanions derived from allyl benzyl thioether

The metalation of allyl benzyl thioether involves the benzylic or the allylic hydrogens. The benzylic carbanion undergoes a rapid[2,3] sigmatropic shift whereas the allylic carbanion gives rise to various rearrangements, among them migration of the allylic unit to the para position with allylic inversion. The temperature dependence of the ratio of products arising from the benzylic carbanion vs those from the allylic carbanion shows that the allylic-to-benzylic carbanion transformation occurs only under special conditions: (a) with slow addition of the base; (b) with thioether in excess relative to the base, and (c) on raising the temperature of the reaction medium from ?78° to ?15°. In the last instance, the proton transfer is intramolecular as shown with labeled thioethers. The extent of the different rearrangements depends on the temperature and solvent. A choice of mechanism cannot be made at this time for the para migration 5→9a. A leaving group effect on the reaction regioselectivity of the carbanion from allyl methyl thioether with benzyl halides has been noticed. The presence of dibenzyl indicates that, in addition to S_N2 reactions, some electron transfer process is occurring.     

Identification of selenium species in urine by ion-pairing HPLC–ICP–MS using laboratory-synthesized standards

This study focused on the detection/identification of possible selenium metabolites in human urine. Organoselenium compounds not commercially unavailable were synthesized and characterized by electrospray mass spectrometry. Separation of selenomethionine, methylselenomethionine, trimethylselonium, selenoethionine, and selenoadenosylmethionine was achieved by ion-pairing HPLC with a mobile phase of 2 mmol L^–1 hexanesulfonic acid, 0.4% acetic acid, 0.2% triethanolamine (pH 2.5), and 5% methanol. The column effluent was introduced on-line to inductively coupled plasma–mass spectrometry for selenium-specific detection (⁷⁷Se and ⁷⁸Se). For selenium speciation in urine, solid-phase extraction was carried out using C₁₈ cartridges modified with hexanesulfonic acid. Selective retention of cationic species was observed from acidified urine (perchloric acid, pH 2.0). After elution with methanol, evaporation, and dissolution in the mobile phase, the sample was introduced to the HPLC–ICP–MS system and the chromatographic peaks were assigned by adding standards. The species identified in urine were selenomethionine, trimethylselonium ion, and selenoadenosylmethionine. The last species was detected for the first time and our results suggest that selenomethionine might enter the metabolic pathway of its sulfur analog in the activated methylation cycle.Kazimierz Wrobel and Katarzyna Wrobel are on the leave from the Institute of Scientific Research, University of Guanajuato, L. de Retana No. 5, 36000 Guanajuato, Gto., Mexico     

A way of establishing quality of measurements in gas analysis—national and international aspects

Standardising quality of measurements at both the national and international level results in a unity in measurement that may be regarded a synonym of traceability. In gas analysis, the key issue in achieving this aim is production of gaseous reference materials. Establishing a network of secondary measurement standards at gaseous CRM producers’ sites in Ukraine might be interesting for those involved in gas analysis activities. Inevitably, problems concerning the recognition of measuring capabilities of both national metrological institutes and local CRM producers are now an international issue. Thus, the problems of national adoption of international standards, as well as harmonisation between different international documents are currently relevant, and Ukrainian experience may be useful to others in this field. Presented at the 3rd International Conference on Metrology, November 2006, Tel Aviv, Israel.     

Bibliometric Analysis of the <Emphasis Type="Italic">Journal of Structural Chemistry</Emphasis>

Bibliometric analysis has been carried out for the Journal of Structural Chemistry (JSC) published since 1960 by the Siberian Branch of the Russian Academy of Sciences. All JSC publications which appeared between 1960 and 2002 have been chosen online from the Chemical Abstracts and Science Citation Index databases of the STN International net and analyzed according to topics, authors, affiliations, and other criteria. JSC authors and publications with the largest numbers of citations have been identified. The impact factor has been determined for JSC 2002.Original Russian Text Copyright © 2004 by V. M. Buznik, I. V. Zibareva, V. N. Piottukh-Peletskii, and N. I. Sorokin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1142–1153, November–December, 2004.