Isotopic analysis of single uranium and plutonium particles by chemical treatment and mass spectrometry

The isotopic composition of single uranium and plutonium particles was measured with an inductively coupled plasma mass spectrometer (ICP-MS) and a thermal ionization mass spectrometer (TIMS). Particles deposited on a carbon planchet were first analyzed with an energy dispersive X-ray spectrometer (EDX) attached to a scanning electron microscope (SEM) and then transferred on to a silicon wafer using a manipulator. The particle on the silicon wafer was dissolved with nitric acid and the isotopic ratios of U and Pu were measured with ICP-MS and TIMS. The results obtained by both methods for particles of certified reference materials showed good agreement with the certified values within the expected uncertainty. The measurement uncertainties obtained in this study were similar for both mass spectrometric methods. This study was performed to establish the method of particle analysis with SEM, EDX, the particle manipulation and chemical preparation technique, and the measurement of isotopic ratios of U and Pu in a single particle by mass spectrometry.     

Age determination of single plutonium particles after chemical separation

Age determination of single plutonium particles was demonstrated using five particles of the standard reference material, NBS 947 (Plutonium Isotopic Standard. National Bureau of Standards, Washington, D.C. 20234, August 19, 1982, currently distributed as NBL CRM-137) and the radioactive decay of ²⁴¹Pu into ²⁴¹Am. The elemental ratio of Am/Pu in Pu particles found on a carbon planchet was measured by wavelength dispersive X-ray spectrometry (WDX) coupled to a scanning electron microscope (SEM). After the WDX measurement, each plutonium particle, with an average size of a few μm, was picked up and relocated to a silicon wafer inside the SEM chamber using a micromanipulator. The silicon wafer was then transferred to a quartz tube for dissolution in an acid solution prior to chemical separation. After the Pu was chemically separated from Am and U, the isotopic ratios of Pu (²⁴⁰Pu/²³⁹Pu, ²⁴¹Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu) were measured with a thermal ionization mass spectrometer (TIMS) for the calculation of Pu age. The age of particles determined in this study was in good agreement with the expected age (35.9 a) of NBS 947 within the measurement uncertainty.     

ENERGY AND MASS TRANSPORT PROCESSES IN THE GRANULAR BED OF AN INDIRECTLY HEATED ROTARY KILN

The transport mechanisms of momentum,mass,species,and energy are invertigated in detail for the ro-tary kiln process.The residence time prediction of the granular bed is well improved by considerng differet flow patterns in the drum.Introducing a mixed flow pattern of the basic slipping and slumping behaviour has the most important effect on the improvement of the residence time prediction.The granular bed is assumed to hehave as a Bingham fluid in the active layer of the bed.The transport mechanisms of momentum,species,and energy are modelled on the basis of this assumption and using the kinetic gas theory.Additionally,a mathematical transformation is presented to save comput a-tional time.The model results of the temperature field are in very good agreement with experimental data.     

Nichtsteroidale entzündungshemmer. 13. Bis-(4-methoxyphenyl)-2-arylthiopyrimidine

The synthesis of 4,5-bis-(4-methoxyphenyl)-2-arylthio- and 4,6-bis-(4-methoxyphenyl)-2-arylthiopyrimidines are described. The phenylthio, 4-fluorophenylthio-, 2-thienylthio derivatives were prepared.     

Peptide thioester formation using standard Fmoc-chemistry

A highly efficient and simple Fmoc-based preparation of peptide ^αthioesters is presented. After Fmoc/t-butyl solid-phase synthesis on 2-chlorotrityl resin the C-terminal carboxylic group of the protected peptide is directly converted to the corresponding thioester. The method leads to very high yields, shows a low level of epimerization and can be easily applied also for the preparation of long peptide ^αthioesters as demonstrated for the 41 amino acid N-terminal fragment of pro-neuropeptide Y (proNPY 1-40).     

Zum zweidimensionalen Wärmetransport bei chemisch-kinetisch veränderlichen Stoffwertefunktionen Dargestellt am Beispiel des Koksofens

Zusammenfassung Die Berechnung des Wärmetransports bei chemisch-kinetisch veränderlichen Stoffwerten wird am Beispiel der Kammerverkokung dargestellt. Das Modell erlaubt die Ermittlung der zweidimensionalen Temperaturfelder. Erfaßt wird die Aufheizung des feuchten Gutes auf die Siedetemperatur des Wassers und der Massenverlust durch thermische Zersetzungsreaktionen. Die Stoffwerte werden nach Modellen berechnet. Der stoffliche Wandel der dispersen Kohleschüttung in die kontinuierliche Feststoffphase wird ebenso berücksichtigt wie die Kinetik der thermischen Zersetzung des Ausgangsstoffes.

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On two-dimensional heat transport in the case of chemo-kinetically variable functions of properties Illustrated by the example of a coke oven

The prediction of heat transport in the case of chemokinetically variable properties is explained by the example of coking in a coke oven chamber. The model allows determination of the two-dimensional temperature distributions. Heating of the wet charge to the boiling temperature of water as well as mass losses by thermal decomposition reactions are covered. The physical properties are calculated using models. The material conversion of a disperse coal charge into the continuous solid phase and, at the same time, the kinetics of thermal decomposition of the initial substance are taken into account.

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Formelzeichen B m ganze Kammerbreite - Bi l Biot-Zahl - b l Koeffizient - c _p kJ/kg K isobare spez. Wärmekapazität - c l Massenanteil an Kohlenstoff - e _AkJ/kmol Aktivierungsenergie - Fo l Fourier-Zahl - H m Kammerhöhe - h l Massenanteil an Wasserstoff - h _RkJ/kg spez. Reaktionsenthalpie - h _r kJ/kg spez. Verdampfungsenthalpie - K l Wichtungsfaktor - k _n l/s Reaktionsgeschwindigkeitskoeffizient - k ₀ l/s präexponentieller Faktor - m kg Masse - ¯ n Normalenvektor - n l Massenanteil an Stickstoff - o l Massenanteil an Sauerstoff - Po l Pomerantsev-Zahl - q _R,n mol/m³ s Reaktionsgeschwindigkeit - q _EW/m³ Energiequelldichte - Sf l Stefan-Zahl - s l Massenanteil an Schwefel - s l Schrumpfung - T K Temperatur - t s Zeit - V m³ Volumen - v m³/kg spez. Volumen - v m/s Geschwindigkeit - w l Wasseranteil - x m Breitenkoordinate - x _rad m Strahlungsweglänge - y m Höhenkoordinate - z m allgemeine Variable, Tiefenvariable - _nl Bildungsgrad - l Höhenkennzahl - _Fl Formfaktor - l Porosität - l Lückengrad - _riß l dimensionsloses Rißvolumen - ₀ l Stückkoksporosität - _rad l Strahlungsaustauschzahl - l normierte Höhenkoordinate - l normierte Temperatur - K/s Aufheizgeschwindigkeit - W/mK Wärmeleitfähigkeit - kg/kmol Molmasse - l normierte Breitenkoordinate - kg/m³ Dichte - W/m² K⁴ Stefan-Boltzmann-Konstante - W/m² Wärmefluß Indizes B Besatz - B-GS Grenzfläche Besatz-Gassammelraum - e Erweichung - eff effektiv - f feucht - gas Gasphase - ges gesamt - H-L Grenzfläche Heizzug-Läufer - i, j, k, n Laufindizes - K Kohle- und Koks-Rohsubstanz - KB-B Grenzfläche Kammerboden-Besatz - L Läufer, Lücke - L-B Grenzfläche Läufer-Besatz - M Mitte - max maximal - mol molekular - P Pore - PF Primäre, flüchtige Bestandteile - rad Strahlung - sol Feststoffphase - sp spezifisch - sch Schüttung - tr trocken - v Verfestigung - vol volumetrisch - w wahr - waf wasser- und aschefrei - wmf wasser- und mineralstofffrei - * normiert     

Eine neue Apparatur zur Druckveraschung von biologischem Material

Zusammenfassung Eine neue Apparatur zur Druckveraschung von biologischem Material wird beschrieben. Die Leistungsfähigkeit wurde mit verschiedenen Standardreferenzmaterialien für die Elemente Cd, Cu, Fe, Mn, Pb und Zn getestet und die Ergebnisse beschrieben. Die Analysen wurden mittels Atomabsorptionsspektroskopie und ICP-Spektroskopie durchgeführt. Der Vorteil des Geräts liegt in der einfachen Handhabung, der Möglichkeit der Druckmessung während der Veraschung und der Möglichkeit, Quarzgefäße zu verwenden, die auch gleichzeitig als Lagergefäße dienen können.

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New device for ashing of biological material under pressure

Summary The range of application was tested with different standard reference materials for the elements Cd, Cu, Fe, Mn, Pb and Zn. The results are presented. The analyses were performed by atomic absorption spectroscopy and ICP spectroscopy. This device offers the advantages of easy handling, of possible pressure measurement during the ashing process, and of the use of the quartz vessels, which may also be employed for storing.