Verwendung eines Ge(Li)-Detektors in der radiochemischen Analyse

Zusammenfassung Zur Bestimmung der U- und Th-Gehalte in 0,5–1,5mg wiegenden Mikroproben von ThO₂-UO₂-Kernbrennstoffen wurde die Neutronenaktivierungsanalyse mit zerstörungsfreier-Spektrometrie eingesetzt. Bei Gehalten über 0,1% beträgt die relative Standardabweichung 6%. Der Th-Gehalt der Mikroproben wird durch-spektrometrische Messung des²³³Pa ermittelt; bei Natur-Uran enthaltenden Proben wird der U-Gehalt über²³⁹Np bestimmt, bei hochangereichertes UO₂ enthaltenden Proben über¹³¹J. Mit der beschriebenen Methode können sowohl unbestrahlte als auch bestrahlte ThO₂-UO₂-Kernbrennstoffe untersucht werden.

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Use of a Ge(Li) detector in radiochemical analysisII. determination of U and Th contents in microsamples of ThO²-UO² nuclear fuels

Neutron activation analysis with non-destructive-spectrometry has been used to determine U and Th in microsamples (0.5–1.5 mg) from ThO₂-UO₂ nuclear fuels. With U contents of more than 0.1% the relative standard deviation amounts to 6%. Th in the microsamples is estimated by measuring²³³Pa; in natural UO₂ containing samples²³⁹Np ist measured for U determination, in highly enriched UO₂ samples¹³¹J. Fresh und spent ThO₂-UO₂ nuclear fuels can be investigated by the method described.

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Teil I siehe [3].

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Herrn G. Hofmann danken wir für die Entnahme der Mikro-Bohrproben aus den bestrahlten und unbestrahlten Brennstoffschliffen.     

Influence of increasing zinc contents in brass in the early stages of corrosion investigated by in-situ TM-AFM and SIMS

In-situ tapping mode atomic force microscopy (TM-AFM), a powerful, high-resolution imaging technique for determining the structure of surfaces and ex-situ secondary ion mass spectroscopy (SIMS), a multielement, high-depth-resolution method, were used to examine the influence of increasing zinc contents in brass in the early stages of corrosion. Four different samples (pure Cu, pure Zn, Cu/Zn=90/10 wt% and Cu/Zn=70/30 wt%) were studied in order to determine their chemical behaviour under various atmospheric conditions. The in-situ TM-AFM investigations were carried out in synthetic air with 60% relative humidity (RH) and 80% RH with 250 ppb SO(2). The samples for the ex-situ SIMS experiments were weathered over a period of 60 h in 80% RH and 250 ppb SO(2). The in-situ TM-AFM investigations have shown that an increasing Zn content in brass increases the corrosion rate.     

[(C~8H~8)Y(μ-OC~6H~5)(THF)]~2的合成和晶体结构

本文用(C~8H~8)Y(μ-Cl)(THF)]~2与NaOC~6H~5以1:2摩尔比在四氢呋喃中反应, 合成了新的中性配合物[(C~8H~8)Y(μ-OC~6H~5)(THF)]~2, 经过分离, 在-30℃下培养得到无色晶体, 用元素分析, 核磁共振和质谱进行了鉴定, 并以X-射线衍射测定了晶体结构。     

Polymerization in the crystalline state. IX. Relation between the velocity of radiation-induced in-source polymerization and post-polymerization

A general relation is derived between the polymerization velocities to be expected for crystalline monomers during irradiation at a polymerization temperature and the post-polymerization observed in samples irradiated at very low temperatures and subsequently warmed outside the irradiation source. For acrylamide, the experimental data are in satisfactory agreement with the theoretical relationship. The possible reasons for a deviation from this relationship are discussed.     

Chemical biology of protein lipidation: semi-synthesis and structure elucidation of prenylated RabGTPases

Rab/Ypt guanosine triphosphatases (GTPases) represent a family of key membrane traffic regulators in eukaryotic cells. For their function Rab/Ypt proteins require double modification with two covalently bound geranylgeranyl lipid moieties at the C-terminus. Generally, prenylated proteins are very difficult to obtain by recombinant or enzymatic methods. We generated prenylated RabGTPases using a combination of chemical synthesis and protein engineering. This semi-synthesis depends largely on the availability of functionalized prenylated peptides corresponding to the proteins' native structure or modifications. We developed solution phase and solid phase strategies for the generation of peptides corresponding to the prenylated C-terminus of Rab7 GTPase in preparative amounts enabling us to crystallize the mono-prenylated Ypt1:RabGDI complex. The structure of the complex provides a structural basis for the ability of RabGDI to inhibit the release of nucleotide by Rab proteins and a molecular basis for understanding a RabGDI mutant that causes mental retardation in humans.     

Heating in a stream of oxidizing or reducing gas for the qualitative analysis of inorganic substances

Summary Observation of the phenomena resulting from heating a substance first in air and then in hydrogen is recommended for the preliminary examination of small specimens of inorganic matter. It may permit immediate identification of simple compounds of the heavy metals. Reduction by heating in hydrogen is also recommended for the investigation of acid insoluble residues.

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Zusammenfassung Das Verhalten beim Erhitzen in Luft und dann in einer Wasserstoff-atmosphäre eignet sich für die Vorprüfung kleiner Mengen anorganischer Substanz. In einzelnen Fällen können einfache Verbindungen der Schwermetalle daran erkannt werden. Die Reduktion durch Erhitzen in einer Wasserstoffatmosphäre empfiehlt sich ferner für die Untersuchung säureunlöslicher Rückstände.

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Résumé L'observation du phénomène résultant du chauffage d'une substance dans l'air puis dans l'hydrogène est recommandée comme examen préliminaire de petits échantillons minéraux. Elle peut permettre l'identification immédiate de composés simples des métaux lourds. La réduction par chauffage dans l'hydrogène est également recommandée pour l'examen de résidus insolubles dans les acides.

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Dedicated to Prof.Hans Lieb on occasion of his 70th birthday.     

RAMAN- und infrarotspektrosktroskopische Untersuchungen an Alklyderivaten der Arsensäure. II. Die Schwingungsspektren einiger Alkanarsonsäuredialkylester

RAMAN and IR spectroscopic investigation of alkyl derivatives of arsenic acid. II. Vibrational spectra of some alkanearsonic acid dialkylesters RAMAN and IR spectra of CH₃AsO(OCH₃)₂, CH₃AsO(OC₂H₅)₂, C₂H₅AsO(OCH₃)₂, and C₂H₅AsO(OC₂H₅)₂, are communicated and discussed. Their skeleton CAsO(OC)₂ has very probably C_s symmetry.     

Organometallic Compounds of the Lanthanoides. LXVI. Synthesis and X-ray crystal structure of [O(CH2CH2C5H4)2Y(μ-OH]2 and (MeC5H4)3Ho(H2O), two unusual products of the hydrolysis of organolanthanoide compounds

The partial hydrolysis of [O(CH₂CH₂C₅H₄)₂]Y(C₅H₄CH₃) 1 , [O(CH₂CH₂C₅H₄)₂]Y(C₅H₅) 3 , and [O(CH₂CH₂C₅H₄)₂]Ho(C₅H₄CH₃) 5 results in the formation of [O(CH₂CH₂CH₂C₅H₄)₂Y(μ-OH)₂]₂ 2 , (C₅H₅)₃Y(OH₂) 9 and (MeC₅H₄)₃Ho(OH₂) 11 . The new compounds have been characterized by elemental analyses, IR and NMR spectra. The X-ray structural analyses shows 2 to be monoclinic, space group P2₁/n with a = 1146.0(3), b= 1046.6(3), c = 1514.9(3) pm, β = 94.83(2)°. The molecular structure shows bridging hydroxyl groups with a mean distance Y? O = 223.8(3) pm. 11 crystallizes in the cubic space group 14 3d with a = 1847.9(3)pm with Z = 16 molecules per unit cell. The molecules posses symmetry C₃-3, the coordination is trigonal pyramidal with three methylcyclopentadienyl anions and one water molecule as ligands. The distance Ho? O is 231 pm.