bluuebunny/crossref_metadata_2025 huggingface dataset:
Verbindlichkeit durch netzinterne Sicherheitsdienste (Reaching Accountability by Security Services inside Networks)
Authors: Kreutzer Michael , Zugenmaier Alf
Published: August 2006

Bei der Abwicklung von Geschäften zwischen Personen kommt es nicht nur auf die Möglichkeit zur Kommunikation an. Es sind unter Umständen die zweifelsfreie Identität der Gesprächspartner, der Ort des Geschäftsabschlusses und die Beweisbarkeit von Absprachen von Bedeutung. Bei der natürlichen, unmittelbaren Kommunikation zwischen Menschen sind beispielsweise Identität und Ort der Beteiligten offensichtlich. Die Inhalte können durch einen anwesenden Zeugen glaubhaft bestätigt werden. Diese Eigenschaften der Kommunikation gehen jedoch beim Einsatz von Telekommunikationssystemen verloren. In diesem Beitrag zeigen wir, wie bestehende Telefoniedienste durch neue Mechanismen erweitert werden können, um Aspekte der unmittelbaren Kommunikation wie Verbindlichkeit der Inhalte und des Ortes für geschäftliche Transaktionen auch bei mittelbarer Kommunikation zur Verfügung zu stellen.
Die Zukunft interaktiver Systeme: Herausforderungen an die Usability-Forschung (The Future of Interactive Systems: Challenges to the Usability Research)
Authors: Kirste Thomas , Diener Holger , Encarnação L. Miguel , Hein Oliver , Stork André , Bimber Oliver
Published: August 2006

Weltweit wird an der Entwicklung von Technologien für zukünftige interaktive Systeme gearbeitet, die neue Möglichkeiten bieten, Usability-Probleme zu adressieren. In diesem Beitrag werden einige aktuelle Forschungsansätze des Fraunhofer-Instituts für Graphische Datenverarbeitung zu kontinuierlichen und nichtsymbolischen Interaktionsparadigmen vorgestellt und ihre Auswirkungen auf die Usability-Forschung diskutiert. An konkreten Projekten werden neue Herausforderungen an die Usability-Forschung dargestellt, neuartige Lösungen für Usability-Probleme erläutert und neue Werkzeuge und Frameworks für die Unterstützung des Usability Engineerings vorgestellt.
Einsatz formaler Methoden zur Evaluierung der Gebrauchsfähigkeit interaktiver Geräte (Utilization of Formal Methods for the Usability Evaluation of Interactive Devices)
Authors: Hamacher Nico , Kraiss Karl-Friedrich , Marrenbach Jörg
Published: August 2006

Gebrauchsfähigkeit ist ein wichtiges Attribut interaktiver Systeme. Sie kann empirisch erst ermittelt werden, wenn ein funktionsfähiger Prototyp zur Verfügung steht. Da sich die Entwicklungsprozesse ständig beschleunigen, kommen empirische Ergebnisse jedoch häufig zu spät, um noch in den Entwicklungsprozess einfließen zu können. Dieser Beitrag beschreibt als Alternative den Einsatz formaler Bewertungsmethoden auf Basis normativer Benutzermodelle. Diese erlauben die Bewertung der Gebrauchsfähigkeit bereits auf der Grundlage technischer Spezifikationen. Es wird das Werkzeug TREVIS vorgestellt, das normative Benutzermodelle semi-automatisch aus technischen Spezifikationen generiert und daneben vielfältige Analysemöglichkeiten bereit stellt.
Entwurfsunterstützung zur hardwarebasierten TCP/IP-Beschleunigung (Design Support for Hardware Based TCP/IP Accelerator)
Authors: Benz Mirko , Hatnik Uwe , Feske Klaus , Haufe Jürgen
Published: August 2006

In diesem Beitrag wird ein Ansatz zur Hardwareunterstützung komplexer Transportprotokolle am Beispiel von TCP/IP präsentiert. Dazu wird eine Hardware/Software-Partitionierung sowie eine Protocol Engine zur Beschleunigung der Protokollverarbeitung vorgestellt und deren transparente Integration in existierende Systeme beschrieben. Für Entwurf, Entwicklung und Verifikation derartiger Kommunikationssysteme ist eine umfangreiche Simulationsunterstützung erforderlich. Wir zeigen, wie VHDL-Modelle der Protocol Engine, ein Netzwerksimulator und existierende Applikationen kombiniert wurden, um diesen Prozess zu unterstützen. Zur Steigerung der Entwurfseffizienz wurden Methoden des High-Level-Entwurfs verwendet. Der Ansatz wurde mittels eines FPGA-Board prototypisch validiert, sodass erste Resultate präsentiert werden können.
Metadaten aus Autorensicht – ein Erfahrungsbericht über ein webbasiertes Multimedia-Lernsystem am Beispiel k-MED (Metadata from the Point of View of the Authors – Report of Experience from a Web-based Multimedia Learning System)
Authors: Seeberg Cornelia , Faatz Andreas , Steinmetz R. , Steinacker Achim
Published: August 2006

Um Multimedia-Lernressourcen, die in Modulen vorliegen, effizient zu verwalten, müssen sie geeignet beschrieben sein. Hierfür bietet sich eine dreigeteilte Beschreibungsmethode an, die aus einem zu Grunde liegenden semantischen Netz, Metadaten (LOM) und Relationen zwischen den Modulen besteht. Das bedeutet gegenüber dem herkömmlichen Autorenprozess einen Mehraufwand, der nur mit geeigneten Werkzeugen (Editoren) leistbar ist. Im Projekt k-MED wurden hiermit Erfahrungen gesammelt.
Trends und Perspektiven der virtuellen Hochschule in Deutschland (Trends and Perspectives of Virtual Campus in Germany)
Authors: Zentel Peter , Bett Katja , Meister Dorothee M. , Rinn Ulrike , Wedekind Joachim
Published: August 2006

Die Virtuelle Hochschule wird in Deutschland gegenwärtig stark gefördert. Der Beitrag gibt einen Überblick zu hochschulpolitischen Stellungnahmen sowie Förderprogrammen der Länder und des Bundes. Eine Analyse des aktuellen Förderprogramms Neue Medien in der Bildung lässt Trends im Hochschulbereich erkennen, die auf mögliche Entwicklungen und Hemmnisse bei der Virtualisierung der Hochschullehre hinweisen.
Enterprise-on-Air: Kontextabhängige Dienste für den Firmencampus (Enterprise-on-Air: Context-aware Mobile Enterprise Services)
Authors: Gitsels Martin , Sauter Jochen , Völksen Gerd , Wischy Markus A.
Published: August 2006

Im Projekt Enterprise-on-Air (EoA) wurde eine Umgebung für kontextabhängige Enterprise-Dienste realisiert, auf die mittels Plug&Play-Technologien jederzeit spontan zugegriffen werden kann. Die Dienste unterstützen mobile Benutzer bei ihren täglichen Aktivitäten auf einem großen Firmengelände, wie z.B. bei der Orientierung auf dem Campus oder bei der Organisation und Durchführung von Besprechungen. Der vorliegende Artikel gibt Einblick in die kontextabhängigen Anteile des Projektes, insbesondere die Dienstplattform und die Laufzeitumgebung des Endgerätes.
Connectivity Coding: New Perspectives for Mesh Compression (Connectivity Coding: Neue Perspektiven für die Kompression von Dreiecksnetzen)
Authors: Gumhold Stefan
Published: August 2006

Compact encodings of the connectivity of planar triangulations is a very important subject not only in graph theory but also in computer graphics. For triangle meshes used in computer graphics the topologically planar regions dominate by far. New results by Isenburg et al. [6] even show that the connectivity is sufficient to describe shape by itself. Most coding methods for planar triangulations can be extended to manifolds of bounded genus with the same upper and lower bounds on the bit rate.

In 1962 Tutte enumerated the number of different planar triangulations and his results show, that at least 3.245 bits per vertex are necessary to encode the connectivity graph of planar triangulations. In this article we improve the so far best upper bound [5] and show that the connectivity of a planar triangulation can be encoded with less than 3.525 bits per vertex, while ensuring a linear run time for encoding and decoding.
The 3D Object Pipeline – Capturing, Processing and Interactive Display of Objects with Complex Appearance (Die 3D-Objekt-Pipeline – Akquisition, Verarbeitung und interaktive Darstellung von Objekten mit komplexem Aussehen)
Authors: Lensch Hendrik P. A. , Goesele Michael , Kautz Jan , Seidel Hans-Peter
Published: August 2006

This article highlights some recent results on the capture and interactive display of high quality 3D models with complex appearance. For use in photorealistic renderingor object recognition, a high quality model must capture two things: the shape of the object represented as a geometric description of its surface and the appearance of the materials it is made of, e.g. the object´s color, texture, or reflection properties. The article shows how computer vision and computer graphics techniques can be seamlessly integrated into a 3D object pipeline for capturing, processing, and interactive display of objects with complex appearance.
The formation of mixed-hydroxo complexes of Cm(III) and Am(III) with humic acid in the neutral pH range
Authors: Morgenstern M. , Klenze R. , Kim J. I.
Published: August 2006

The complexation of humic acid with Cm(III) and Am(III) is studied in the neutral pH range from 6 to 10 in 0.1 M NaClO4under Ar-atmosphere. Cm(III) and Am(III) species are characterized and quantified by time-resolved laser fluorescence spectroscopy (TRLFS) and UV/Vis absorption spectroscopy, respectively. The formation of ternary humate complexes, i.e. hydroxo-humate species, is ascertained besides the well known binary complex AnHA(III) (An = Cm(III), Am(III)) by spectroscopic speciation in aid of radiometric quantification. The pH dependent change in concentrations of individual Cm(III) and Am(III) species corroborates ternary humate complex formation: An(OH)HA(II) and An(OH)2HA(I), with stability constants evaluated to be log β111= 12.82 ± 0.11 and log β121= 17.53 ± 0.13 for Cm(III) and log β111= 12.71 ± 0.17 and log β121= 17.40 ± 0.21 for Am(III). The formation of ternary humate complexes culminates in the strong interaction of trivalent actinide ions with humic acid in the neutral pH range as compared to the binary complexation alone. The results are compared with a previous study on the Cm(III) interaction with humic colloids in a real groundwater system.
Complexation studies of UO22+with humic acid at low metal ion concentrations by indirect speciation methods
Authors: Montavon G. , Mansel A. , Seibert A. , Keller H. , Kratz Jens Volker , Trautmann N.
Published: August 2006

The complexation of uranium(VI) with humic acid was studied at pH 4 and 5 in 0.1 mol/l and 4.10-3mol/l NaClO4by indirect speciation methods, i.e., electrophoretic ion focusing (EIF) and anion exchange (AE). The concentration range investigated was from 10-8mol/l to 5 · 10-6mol/l for the uranyl ion and from 1 to 2.5 mg/l for the humic acid. The experimental data obtained by AE are well described by the complexation reaction involving the charge neutralization of the uranyl ion with two exchanging sites of humic acid. The complexation constant calculated by taking the loading capacity values into account is found to be log β = 6.08 ± 0.15. Concerning EIF, an interfering interaction between the humic acid and U(VI), occurring under the effect of the electric field, is evident and makes this separation technique not well suitable for the investigation of the U(VI):humic acid system.
Activities and activity ratios of U and Ra radioisotopes in drinking wells, springs and tap water samples in Morocco
Authors: Hakam O.K. , Choukri A. , Reyss J.-L. , Lferde M.
Published: August 2006

Radiochemical results (234U,238U,226Ra and228Ra activities;234U/238U,228Ra/226Ra and226Ra/238U activity ratios) are reported for 31 drinking water samples collected from 8 wells, 12 hot mineral springs, 5 cold springs, and 6 tap water samples. Activities of the Ra isotopes were measured by gamma spectrometry using a low background and high efficiency well type germanium detector. The U isotopes were counted in an alpha spectrometer. The results show that238U activity varies between 4.46 and about 308 mBq l-1in wells, 0.59 and 17.88 mBq l-1in hot springs, 2.19 and 3.21 mBq l-1in cold springs, and between 2.5 and 15.70 mBq l-1in tap water samples.234U/238U activity ratio is generally higher than 1 which is the equilibrium activity ratio value in closed systems. It varies in the ranges 0.79-2.11 in wells, 0.97-7.39 in hot springs, 2.53-8.30 in cold springs, and 1.14-3.35 in tap water. Unlike well waters, spring waters show low238U activities and high234U/238U activity ratios. The highest activity of Ra measured in hot mineral water samples is about 150 and 352 times higher than the highest activity of Ra found in well waters and in cold springs, respectively.226Ra/238U activity ratios are in the ranges: 0.07-1.14 in wells, 1.79-2115 in hot springs, 0.86-4.79 in cold springs, and 0.18-5.61 in tap water samples. The data are similar to those published for other regions of the world.
On-line gas chromatographic studies of Rf, Zr, and Hf bromides
Authors: Sylwester E.R. , Gregorich K.E. , Lee D.M. , Kadkhodayan B. , Türler A. , Adams J.L. , Kacher C.D. , Lane M.R. , Laue C. , McGrath C.A.
Published: August 2006

The Heavy Element Volatility Instrument (HEVI), an on-line isothermal gas chromatography system, has been used to separate the volatile bromide compounds of the group 4 elements Zr and Hf and the transactinide Rf according to their volatilities, and to provide data on the gas phase chemical properties of very short-lived isotopes in amounts as low as a few atoms. For these studies261Rf was produced via the248Cm(18O, 5n) reaction.165-167Hf was produced via the reactionnatEu(19F, xn), and85Zr was produced via thenatCu(28Si, 3p3n) reaction. The half-life for261Rf was measured to be 75±7 seconds.

A Monte Carlo code was used to deduce the enthalpy of adsorption (ΔHa) from the observed volatility and parameters of the chromatography system. The resulting adsorption enthalpies for the Zr, Hf, and Rf tetrabromides are: -108±5 kJ · mol-1, -113±5 kJ · mol-1 and -87±7 kJ · mol-1, respectively.

Volatilities of the group 4 bromides support the conclusion from previous results for the group 4 chlorides that Rf deviates from the trend expected by simple extrapolation of the properties of its lighter homologs in the periodic table. The group 4 bromides are also observed to be less volatile than their respective chlorides, as predicted by relativistic calculations.
Complex formation of U(VI) with Bacillus-isolates from a uranium mining waste pile
Authors: Panak P. , Raff J. , Selenska-Pobell S. , Geipel Gerhard , Bernhard G. , Nitsche Heino
Published: August 2006

Accumulation studies with vegetative cells and spores of three Bacillus isolates (JG-A 30, JG-A 12, JG-A 22, classified as Bacillus cereus, Bacillus sphaericus, Bacillus megaterium) from a uranium mining waste pile (Johanngeorgenstadt, Saxony) and their corresponding reference strains have shown that Bacilli accumulate high amounts of U(VI) in the concentration range examined (11-214 mg/L). Information on the binding strength and the reversibility were obtained from extraction studies with different extractants. With 0.01 M EDTA solution the uranium bound to the biomass was released almost quantitatively. The characterization of the bacterial-UO22+-complexes by time-resolved laser fluorescence spectroscopy (TRLFS) showed the formation of inner-sphere complexes with phosphate groups of the biomass. The results lead to the conclusion that the cell wall components with phosphate residues e.g., polysaccharides, teichoic and teichuroic acids or phospholipide layers of the membranes are responsible for the uranium binding. The spectroscopic studies of the U(VI)-complexes with isolated bacterial cell walls and isolated surface-layer proteins of the strain Bacillus sphaericus NCTC 9602 after cell fractionation have shown that the complexation of U(VI) with intact cells (vegetative cells or spores) is different from the coordination with isolated cell wall components, especially with the S-layer proteins. For all Bacillus strains studied in this work, a significant contribution of the S-layer proteins to the binding of uranyl to living cells can be excluded.
Longterm leaching of natural radionuclides from uranium mill tailings material: comparison of indoor and outdoor column experiments
Authors: Schimmack W. , Klotz D. , Kretner R. , Bunzl K.
Published: August 2006

The leaching of natural radionuclides from the material of a uranium mill tailing at Crossen/Saxony was investigated using eight columns (20 cm diameter, 50 cm height). Six columns were irrigated in the laboratory by synthetic rainwater of pH 6, 3 and 2, two columns were exposed outdoor to natural meteorological conditions. In the effluent of the columns, the concentrations of the radionuclides were measured periodically. With exception of the initial phase after installation of the columns (ca. 0.4 y), the leaching rates of radionuclides decreased slowly within the observation period of 4.5 years. Due to the buffering capacity of the tailings material, acidifying the irrigation water of the laboratory columns did not effect the effluent concentrations of the radionuclides. However, significant differences were observed between laboratory and outdoor columns: outdoor, the concentration of235U in the effluents was for the first two years substantially smaller than in the laboratory. As a consequence, the accumulated leached activity of235Uduring 4.5 years was 19.0±0.9% of the inventory for the laboratory columns, but only 10.9±0.6% for the outdoor columns. While uranium thus proved to be rather soluble, the concentration of226Ra in the effluents was quite small (<1 Bq/l). Thorium was retained completely in the columns.
Gas phase chemistry of technetium and rhenium oxychlorides
Authors: Eichler R. , Eichler B. , Gäggeler H. W. , Jost D.T. , Piguet D. , Türler A.
Published: August 2006

The chloride and oxychloride chemistry of the group 7 elements Tc and Re was investigated in order to develop an experimental approach to a gas chemical characterisation of bohrium (Bh, element 107). In thermochromatography experiments with trace amounts of101,104Tc and183,184Re the formation of one volatile compound was observed in O2/HCl containing carrier gas, which was attributed to MO3Cl (M = Tc, Re). From the measured deposition temperatures the adsorption enthalpies on quartz surfaces ΔHads(TcO3Cl) = -51 ± 3 kJ/mol and ΔHads(ReO3Cl) = -62 ± 3 kJ/mol were evaluated. The sublimation enthalpies were derived using an empirical correlation between Δ Hadsand ΔHsubl: ΔHsubl(TcO3Cl) = 49±10 kJ/mol and ΔHsubl(ReO3Cl) = 67±10 kJ/mol. A fast gas chemical separation technique for highly volatile compounds of short-lived isotopes based on isothermal gas solid adsorption chromatography (OLGA-principle) was developed. With a modified OLGA device, model studies with the short-lived nuclides106,107,108Tc and169,170,174,176Re were carried out in preparation of an experimental gas chemical investigation of bohrium (Bh, element 107). Separation times of less than 3 s were achieved. A good separation of the oxychlorides of group 7 elements from chloride and oxychloride compounds of152-155Er,151-154Ho (as models for actinide elements),98-101Nb,99-102Zr (as models for light transactinide elements),218Po, and214Bi was accomplished in this chemical system.
Synthesis and chromatographic characterization of [Tc-99m]technetium-humic acid species
Authors: Rößler D. , Franke K. , Süß R. , Becker E. , Kupsch H.
Published: August 2006

A natural moor soil humic acid (HA) was labeled with Tc-99m via reduction of pertechnetate with stannous chloride. The humic acid species obtained were characterized by thin layer chromatography (TLC), gel permeation chromatography (GPC), sequential chromatographic analysis (SCA), paper electrophoresis and micropore filtration. Labeling was found to take place in all ranges of molecular weight. Due to the complex humic acid composition and the formation of hydroxo species the labeling yields strongly depend on the separation conditions, ranging from 42% to 80%. The pH-dependent distribution of mobile and immobile species was determined by SCA for HTcO4, HA and for Tc-HA-species obtained after labeling. Geochemically relevant properties of HA remain unchanged after the labeling procedure, only macroscopic amounts of the reducing agent Sn2+give rise to a shift to lower molecular weight species.
Separation of carrier-free cerium radionuclides from different target matrix produced by heavy ion beams
Authors: Nayak D. , Lahiri S.
Published: August 2006

Heavy ion activation of natural Sb2O3 with 78 MeV 16O6+ results in the formation of carrier-free praseodymium isotopes, 133,135Pr, and their corresponding decay products 133,135Ce, in the matrix. Also irradiation with ~ 90 MeV 19F7+ beam leads to the production of carrier-free neodymium isotopes, 135-138Nd, which decay out to 135-138Ce via 135-138Pr. Another way for the production of carrier-free 135Ce radionuclide is to irradiate CsNO3 target with 7Li3+ beam of energy 44 MeV. The shorter lived radionuclides of cerium decay out and a radiochemical procedure has been developed for the separation of carrier-free radionuclides from the bulk target matrix antimony and caesium through liquid-liquid extraction (LLX) using Aliquat 336 (tricaprylmethylammonium chloride), and di-(2-ethylhexyl)phosphoric acid (HDEHP) as extractants.
The centenary of a controversial discovery: actinium
Authors: Adloff J. P.
Published: August 2006

André Debierne, collaborator of Pierre and Marie Curie, announced in 1900 the discovery of actinium, a third radioelement in pitchblende with properties resembling those of thorium. Four years later, Friedrich Giesel found a substance with a strong emanating power following lanthanum and which he called emanium. It become progressively clear that actinium and emanium were the same element. The arguments developed in the ensuing controversy are reviewed. Eventually Debierne was recognized as the discoverer of actinium, element 89 in the periodic table.
Lutetium-177-EDTMP for bone pain palliation. Preparation, biodistribution and pre-clinical studies
Authors: Solá G.A.R. , Argüelles M.G. , Bottazzini D.L. , Furnari J.C. , Parada I.G. , Rojo A. , Ruiz H.V.
Published: August 2006

Beta emitting radionuclides have demonstrated excellent properties for radionuclide endotherapy using appropriate carrier molecules. In an effort to search for alternative radionuclides, the preparation of 177Lu-EDTMP was undertaken, as a palliative agent for bone metastasis. Natural Lu2O3 was irradiated at the RA-3 Nuclear Reactor of the Ezeiza Atomic Center (Argentina). The optimum molar ratio of Lu:EDTMP, the radiochemical purity, the in vivo and in vitro stability and the biological behaviour in Wistar rats and New Zealand rabbits were studied. The results indicate that an excellent alternative therapeutic radiopharmaceutical, with comparable characteristics as its 153Sm-EDTMP counterpart, was successfully achieved.
11C-methane production in small volume, high pressure gas targets
Authors: Buckley K.R. , Huser J.M. , Jivan S. , Chun K.S. , Ruth T.J.
Published: August 2006

The parameters affecting the production of11C-methane, in situ, in small volume, high-pressure gas targets include target chamber size and material. The results are based on experiments that varied the target gas composition, the target material and geometry. Methane production yields were typically 65% of the yields of11CO2in the same target chamber.
Determination of trace impurities in iron-based alloy using neutron activation analysis
Authors: Zaidi Jamshed H. , Waheed S. , Ahmad Shujaat
Published: August 2006

A radiochemical neutron activation analysis procedure has been developed and applied to investigate 40 major, minor, and trace impurities in iron-based alloy. A comparison of RNAA and INAA indicated a significant improvement in the detection limits. The extensive use of these alloys in the heavy mechanical industry, manufacturing of aircraft engines, nuclear applications, medical devices and chemical equipment requires their precise characterization. The concentration of iron in the iron-based alloy was found to be 86.7%, whereas Ca, Cr, K, Mg, Mn, V and W were the other constituents of the alloy, which constituted to around 12.89%. The rest of the elements were present in minor or trace levels. Most of the rare earth elements were also present in trace amounts.
Investigation of 50Cr(d,n)51Mn and natCr(p,x)51Mn processes with respect to the production of the positron emitter 51Mn
Authors: Klein A.T.J. , Rösch Frank , Qaim Syed M.
Published: August 2006

The positron emitter 51Mn (t1/2 = 46.2 min, Iβ+
= 97%) is of potential interest in positron emission tomography (PET). With a view to optimizing its production route, excitation functions for deuteron induced nuclear reactions on isotopically enriched (~95%) 50Cr were determined radiochemically over the energy range of 3 to 13 MeV and for proton induced nuclear reactions on natCr in the range of 18 to 38 MeV. Cross sections are presented for the reactions: 50Cr(d,2n) 50mMn, 50Cr(d,n) 51Mn, 50Cr(d,t)49Cr, 50Cr(d,p)51Cr, 50Cr(d,a)48V, 52Cr(d,2p)52V, natCr(p,x) 51Mn, natCr(p,x)52Mn, natCr(p,x)52mMn, natCr(p,x)54Mn, natCr(p,x)48Cr, natCr(p,x)49Cr, natCr(p,x) 51Cr, natCr(p,x)48V and natCr(p,x)45Ti. In the case of proton induced reactions on natCr, the isomeric cross section ratio for the isomeric pair 52m,gMn was also determined. The results are interpreted in terms of the spins of the two isomers concerned. Theoretical thick target yields were derived from the corresponding excitation functions. The maximum achievable thick target yield of 51Mn is 1.1 GBq/μAh in the case of the 50Cr(d,n) 51Mn reaction at Ed = 14 → 3 MeV, and 3.2 GBq/μAh in the case of the natCr(p,x)51Mn process for Ep = 40 → 20 MeV. The 50Cr(d,n) 51Mn process is the favourable production route for 51Mn, since the radioisotopic purity is high and a small-sized medical cyclotron is adequate to produce this positron emitter in sufficient quantities.
Target-dependence of light fragment production in photonuclear reactions at intermediate energies
Authors: Matsumura Hiroshi , Washiyama K. , Haba Hiromitsu , Miyamoto Y. , Oura Y. , Sakamoto K. , Shibata S. , Furukawa M. , Fujiwara I. , Nagai  , Kobayashi Takayuki , Kobayashi K.
Published: August 2006

Yields of7Be,10Be,22Na,24Na and28Mg produced fromnatB,natC,natO,23Na,27Al,natSi,natS,natCl,natK,natCa,natV,55Mn,natFe,59Co,natNi,natCu,89Y,natAg,natIn,141Pr,159Tb,165Ho and197Au in irradiations with bremsstrahlung having maximum end-point energies up to 1200 MeV were measured by γ-ray spectrometry (7Be,22Na,24Na and28Mg) and accelerator mass spectrometry (10Be). The yields of heavier fragments,39Cl,43, 44m, 44g, 46, 47, 48Sc,59Fe, and56, 57, 58, 60Co, were also measured by γ-ray spectrometry in order to survey the relative contribution of fragmentation to spallation and/or fission in the mass yield curves. A distinct difference of the target mass-dependence of these yields has made it possible to disentangle the contributions of photospallation and photofragmentation processes. It was found that the neutron-to-proton ratios of targets strongly affect the formation of the nuclei by fragmentation as revealed in the yields of the isotopic pairs as well as of the single isotopes. The photon results were compared with those of proton-induced reactions, and no clear effect due to the difference of the initial interactions of photons and protons with nuclei was found in the fragment yields.
Uranium(VI) complexation with citric, humic and fulvic acids
Authors: Lenhart J.J. , Cabaniss S.E. , MacCarthy P. , Honeyman Bruce D.
Published: August 2006

The binding of uranium(VI) by Suwannee River humic and fulvic acids was studied at pH values of 4.0 and 5.0 in 0.10 M NaClO4using an ion-exchange technique. Few data sets currently exist for metal binding to different molecular weight fractions from the same source. The complexation of U(VI) by citric acid was also studied under the same experimental conditions in order to "calibrate" the experimental and modeling approaches. For the citric acid system, the experimental results were analyzed using Schubert´s ion-exchange method, which indicated the formation of only a 1:1 uranyl-citrate complex. Close agreement was found for the values of log β1,1(6.69±0.03 at I = 0.10) determined from nonlinear regression of data collected at pH values of 4.0 and 5.0. This value represents a more direct measurement of the binding constant for the 1:1 uranyl-citrate complex than do other existing literature values derived from experimental data requiring the simultaneous consideration of 1:1 and 2:2 species.

Both humic and fulvic acids were demonstrated to strongly bind U(VI), with humic acid forming slightly stronger complexes and exhibiting greater pH dependence. Analyses of the data for the humic and fulvic acid systems using the Schubert´s equation previously applied to the citrate system result in an apparent nonintegral number of ligands binding the uranyl ion. Schubert´s method is only appropriate for interpreting mononuclear complexes with integral moles of binding ligands. Thus, a more elaborate binding model was required and the data were interpreted assuming either: (1) a mixture of 1:1 and 1:2 uranyl-ligand complexes or (2) a limited number of high affinity sites forming a 1:1 complex. While both of these modeling approaches are shown to provide excellent fits to the data, the second is deemed more appropriate given the large size of humic and fulvic acid molecules as well as previous results obtained with other metal cations, such as Cu(II).
Boehmite sorbs perrhenate and pertechnetate
Authors: Zhang Pengchu , Krumhansl J.L. , Brady P.V.
Published: August 2006

Boehmite and Al-oxyhydroxide gels sorb ReO4
-, a non-radioactive analogue of TcO4
- from NaNO3 solutions. Sorption appears to be substantially electrostatic (though there appears to be a specific preference for ReO4
- over NO3
-) and is most effective at pH < 8. Measured Kd´s lie between 5 and 105 ml g-1, depending on the solid, pH, and ionic strength. ReO4
- and TcO4
- are both partially removed from high pH Hanford-type acid waste simulants upon neutralization and formation of Al-rich sludges. We therefore propose that sequestration of Tc by boehmite limits dissolved Tc levels in the near and sub-surface environment and for that purpose boehmite might be relied on as a backfill, or reactive barrier, to limit environmental transport of Tc.
Recoil properties of radionuclides formed in photospallation reactions on complex nuclei at intermediate energies
Authors: Haba H. , Matsumara H. , Sakamoto K. , Oura Y. , Shibata S. , Furukawa M. , Fujiwara I.
Published: August 2006

The recoil properties of 14, 24, 26, 31, 21 and 20 radionuclides formed in photospallation reactions onnatV,natCu,93Nb,natAg,natTa, and197Au, respectively, induced by bremsstrahlung of end-point energies (E0) from 600 to 1100 MeV, have been investigated using the thick-target thick-catcher method based on the two-step vector model. The measured forward-to-backward ratios (F/B) were found to be independent of the mass difference (ΔA) between a product (Ap) and a target (At) and also of At. The recoil velocities ν from the first step and the mean kinetic energies T of the residual nuclei in the second step were deduced and discussed by comparing with the reported results on proton-induced reactions. A comparison with T values calculated by the PICA (Photon-Induced Intranuclear Cascade Analysis) code at E0= 400 MeV was also performed. It was found that although the code well reproduces the experimental results ofnatV andnatCu, the same calculation for heavier targets gives T values lower than the experimental results, indicating some nuclear-structure effect, such as a medium effect notably at At≥ 100. The parameter values of εs= T/(ΔA/At), the average kinetic energy of the emitted particles in a random-walk process of both the photon- and proton-reactions, were found to increase along with an increase of At, but change slopes to become constant above At= 100.
A device for on-line electromigration measurements of radioelements in free electrolytes
Authors: Mauerhofer E. , Kling O. , Hiller K. , Rösch Frank
Published: August 2006

An electromigration device has been developed for the on-line measurement of absolute individual ion mobilities of radioactive species in free electrolytes. The device is composed of a migration cell, a γ-radiation scanning unit and a data processing system. The performance of two BGO-scintillators as scanning unit and the reliability of an on-line data processing system were studied with calibrated radioactive sources of given velocities. The system was found to work with a high reproducibility rate. The migration velocities were determined with an accuracy better than 1%.
Interaction of europium with humic acid covalently bound to silica beads
Authors: Czerwinski K.R. , Cerefice G.S. , Buckau Gunnar , Kim J. I. , Milcent M.-C. , Barbot C. , Pieri J.
Published: August 2006

The uptake of Eu3+(a trivalent actinide homolog) by Aldrich humic acid covalently bonded to an inorganic support is examined. Two types of covalent linkages are used and the synthetic routes to produce the resins are discussed. The use of these resins excludes having to account for humic acid desorption from the surface, yields a well characterized system, and allows the experiment to focus on and account for the role of humic acid in the sorption of Eu. The proton exchange capacity of the resins is examined by titration and the differences observed are traced to the resin synthesis. Europium sorption experiments are performed at pH 4 and pH 6 in 0.1 M NaClO4. Kinetic experiments show equilibrium is reached in 24 hours. The kinetic data are used to evaluate the loading capacity, with results similar to equilibrium experiments. The complexation results are evaluated based on the metal ion charge neutralization model. For the resins an effect of pH and resin synthesis route on the Eu uptake is observed. The uptake increases with pH for both resins. The resin HA-Epo (Epoxy linkage) has a higher metal binding at pH 4, while the resin HA-HAB (2-hydroxylazobenzene linkage) had more proton exchange sites occupied by metal ions at pH 6. Overall, more Eu is bound to HA-Epo at pH 6 since its proton exchange capacity is higher. The evaluated stability constants vary slightly and show a dependence on the linkage group but are similar to literature values that examined complexation by aquatic humic acid analyzed with the same model. This result supports the utility of the metal ion charge neutralization model and the applicability of the resulting stability constants.
Contribution of the concept of simple solutions to calculation of the density of ternary and quaternary solutions of thorium(IV) or plutonium(IV) nitrate: An(NO3)4/UO2(NO3)2/HNO3/H2O
Authors: Charrin N. , Moisy Philippe , Blanc P.
Published: August 2006

A method is presented for calculating the density of concentrated ternary and quaternary mixtures of nitric acid, thorium(IV) nitrate or plutonium(IV) nitrate, and uranyl nitrate. The method is based on the concept of simple solutions and on the known binary data for each of the electrolytes. The deviation between the calculated and measured density values for ternary An(NO3)4/HNO3/H2O mixtures was less than 0.3% for densities of up to 1.797 g × cm-3 in the case of Pu(NO3)4. Density predictions for quaternary mixtures containing uranyl nitrate as the additional electrolyte were also investigated; the results show that the density of such mixtures can be predicted with less than 0.4% error, even at very high concentrations (1.836 g × cm-3) in the case of Pu(NO3)4.
Improvement in radiochemical and γ-counting procedures for the determination of 234Th in seawater
Authors: Schmidt Sabine , Reyss J.-L.
Published: August 2006

Procedures have been improved for the measurement of dissolved 234Th in seawater on 20-l volume samples, using a single γ counting. The shortened 234Th protocol can be conducted at sea for radiochemical purification. Subsequent low-level gamma counting is done at the laboratory for the determination of the 229Th yield tracer, 234Th, and, depending of its activity, of 228Th. It offers an easy and fast method for 234Th analyses. This new approach avoids time-consuming extraction and plating procedures used previously and reduces counting errors associated with multiple counting sessions.
Sorption study of strontium onto hydrated cement phases using a sequential desorption method
Authors: Iwaida T. , Nagasaki S. , Tanaka S.
Published: August 2006

We studied the sorption behavior of Sr onto calcium-silicate-hydrates (C-S-H), calcium-aluminate-hydrates ettringite (AFt), monosulphate (AFm), and hydrogarnet (C3AH6) by applying a sequential desorption method. The results showed that:

- The distribution coefficients (Kd) of Sr sorption onto C-S-H increased with decreasing Ca/Si ratios of C-S-H. This Kdchange is explained with the zeta potentials of C-S-H at various Ca/Si ratios and with the change of surface functional group,

- Sr is sorbed on C-S-H through plural sorption forms. The observation that some Sr is desorbed by EDTA and nitric acid suggests that a replacement of Ca with Sr takes place in the C-S-H structure, and

- Sr is structurally incorporated into AFt, AFm, and C3AH6.
Trace detection of 41Ca in nuclear reactor concrete by diode-laser-based resonance ionization mass spectrometry
Authors: Müller P. , Blaum K. , Bushaw B.A. , Diel S. , Geppert Ch. , Nähler A. , Nörtershäuser W. , Trautmann N. , Wendt K.
Published: August 2006

The content of the long-lived isotope 41Ca in concrete samples obtained from the biological shield of a shut-down nuclear research reactor has been determined by diode-laser-based resonance ionization mass spectrometry (RIMS). Standard procedures were applied for the chemical separation of calcium. A radioactive tracer of 47Ca was used to determine the chemical yield. The total calcium concentration in the final nitric acid solution was measured by x-ray fluorescence (XRF) spectroscopy. The RIMS measurement yielded the abundance of 41Ca relative to the total calcium content with a detection limit of 5×10-10, limited by background effects at mass 41. The detection limit corresponds to a minimum detectable specific 41Ca activity of ~100 mBq/g in the concrete. Reproducibility and accuracy were determined with 41Ca spikes and found to be in the range of 15%, limited predominantly by ion counting statistics.
Preparation of188Re-lanreotide peptide and its quality control
Authors: Mushtaq A. , Pervez S. , Haider I.
Published: August 2006

A simple method is described for the preparation of188Re-Lanreotide, a radiolabeled synthetic peptide derived from an analogue of somatostatin, using Lanreotide (50 μg) and stannous tartrate to which is added carrier-free188Re. The radiolabeling has been carried out with ~555 MBq (15 mCi) with a >95% labeling efficiency and no need for subsequent purification. ITLC and HPLC techniques were employed for monitoring the stability and labeling yield. Radiolabeling results in one major peak when analyzed by reverse-phase (RP) HPLC.
The influence of near field hydrogen on actinide solubilities and spent fuel leaching
Authors: Spahiu Kastriot , Werme L. , Eklund U.-B.
Published: August 2006

Large amounts of hydrogen are produced as a result of the anoxic corrosion of iron in the proposed container materials for some geologic repositories. Another hydrogen source, less important than the anoxic corrosion of iron, is the radiolysis of water by the spent fuel radiation. Gas phase formation occurs when the pressure of the hydrogen equals at least the hydrostatic pressure, around 5 MPa at 500 meters depth. The effects of 5 MPa hydrogen pressure on spent PWR fuel leaching and on uranium oxide solubility have been studied in carbonated solutions at 70 °C. The experiments were performed in a 1 liter autoclave, filled with 950 ml of a solution 10 mM NaCl, 2 mM NaHCO3 and with hydrogen at a pressure of 5 MPa in the remaining 50 ml free volume. The leaching behavior of 2 g PWR spent fuel powder of the 0.25-0.50 mm fraction, placed in a gold basket was studied during several months by analyzing 10 ml solution samples taken after regular time intervals. A few experiments were performed also with unirradiated U(IV) oxide. In both cases extremely low concentrations of uranium (less than 10-9 M were measured in the solution samples. Furthermore the uranium levels in solution remained practically constant during the whole leaching period (more than one year), indicating the absence of any oxidative dissolution of the spent fuel matrix. The same conclusion is confirmed by the constant (within analytical errors) levels of strontium, cesium, molybdenum, iodine and technetium during the whole leaching period. These results have been compared with the ones obtained during the leaching of a spent fuel pin in anoxic conditions, where the uranium and other radionuclides levels are several orders of magnitude higher.

The surface of spent fuel or U(IV) oxide is partially oxidized during storage, giving rise to relatively high levels of U(VI) in solution even during leaching in anoxic conditions. No such effect could be observed in the presence of 5 MPa hydrogen, indicating that this initial amount of U(VI) should have been reduced to U(IV). The experimental study of the influence of various parameters as temperature and pressure is still in progress.
Analysis of Th(IV)-humate by XPS
Authors: Schild D. , Marquardt Christian M.
Published: August 2006

The tetravalent actinide humate complexation was investigated for types of bonding between Th(IV) and humic acid. The Th(IV)-humate was prepared in solution, separated by ultrafiltration and analyzed by X-ray photoelectron spectroscopy (XPS). The stability of humic acid against X-ray induced degradation was verified by high-resolution XPS during long-term irradiation. The Th 4f7/2line of Th(IV)-humate can be fitted by one Gaussian-Lorentzian function, indicating that one type of bonding is mainly involved in the complexation. The Th 4f spectrum of Th(IV)-humate is, as compared to those of other Th(IV)-compounds, similar to the Th(IV)-complex with an ion exchanger containing carboxylic functional groups only. The present XPS study corroborates EXAFS results, according to which Th(IV) is predominantly bound to carboxylic groups of humic acid and demonstrates the applicability of the XPS technique for the characterization of metal-humate complexes.
EXAFS structural analysis of aqueous uranium(VI) complexes with lignin degradation products
Authors: Roßberg A. , Baraniak L. , Reich T. , Hennig C. , Bernhard G. , Nitsche Heino
Published: August 2006

Uranium LIII-edge extended X-ray absorption fine structure (EXAFS) analysis was carried out on aqueous uranium(VI) complexes with monomeric intermediates of the natural wood-degradation process such as protocatechuic acid (3,4-dihydroxybenzoic acid), catechol (2-hydroxyphenol), pyrogallol (1,2,3-trihydroxybenzol), and vanillic acid (4-hydroxy-3-methoxybenzoic acid). The structural parameters of the 1:1 complexes with protocatechuic acid and vanillic acid in weakly acidic solution indicate that the carboxylic group coordinates the uranyl cation in a bidentate mode in the equatorial plane. Based on the identical structural parameters observed for protocatechuic acid, catechol and pyrogallol in alkaline media, we conclude that the coordination with uranium occurs via the neighboring OH groups of the phenols under formation of a five-membered ring.
Reduction of Pu(V) by humic acid
Authors: André C. , Choppin Gregory R.
Published: August 2006

The reduction of Pu(V) by humic acid in the presence of divalent cations (calcium and magnesium) was investigated. Tracer concentrations of238Pu were used (ca. 10-10M). Experiments were run in 5 m NaCl in the dark at pcH values of 6 and 8 with humic acid concentrations between 0 and 10 ppm. The redox speciation of plutonium was determined by solvent extraction methods. The reduction of Pu(V) by humic acid in the absence of divalent cations was investigated also with samples exposed to light prior to or after the introduction of plutonium. The presence of divalent cations, as well as light exposure increased the reduction of Pu(V), compared to when experiments were run in the dark without divalent cations.
The Rossendorf Beam Line ROBL – a dedicated experimental station for XAFS measurements of actinides and other radionuclides
Authors: Reich T. , Bernhard G. , Geipel Gerhard , Funke H. , Hennig C. , Roßberg A. , Matz W. , Schell N. , Nitsche Heino
Published: August 2006

X-ray absorption fine structure (XAFS) spectroscopy is a powerful tool for obtaining basic molecular-level information, which is required for a better understanding of the mechanisms responsible for radionuclide transport in the environment. A unique experimental station dedicated to the study of actinides and other radionuclides by XAFS spectroscopy has become operational at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The main characteristics of the Rossendorf Beamline, ROBL, and its radiochemistry end station and selected results obtained on Tc and Np solutions are presented.
Uranium(VI) sorption onto phyllite and selected minerals in the presence of humic acid
Authors: Schmeide K. , Pompe S. , Bubner M. , Heise K. H. , Bernhard G. , Nitsche Heino
Published: August 2006

We studied the influence of humic acid (HA) on the uranium(VI) sorption onto the rock material phyllite and onto its main mineral constituents quartz, muscovite, chlorite, and albite at an ionic strength of 0.1 M in the pH range of 3.5 to 9.5 under aerobic conditions. The uranium(VI) concentration was 1 × 10-6M and the HA concentration was 5 and 60 mg/L, respectively. The solid/solution ratio was 12.5 g/L. Furthermore, we studied the uranium and HA sorption on ferrihydrite (3 × 10-4M Fe) and compared the results to the sorption behavior of phyllite. The study showed that the uranium sorption onto phyllite and onto its mineral constituents is influenced by the pH-dependent sorption behavior of the HA. Due to high HA sorption onto the solids in the acidic pH range the uranium uptake is enhanced compared to the uranium uptake in the absence of HA. A high concentration of dissolved HA in the near-neutral pH range reduces the uranium sorption due to formation of aqueous uranyl humate complexes. Furthermore, we could show that the high uranium and HA sorption on phyllite is primarily caused by minor amounts of the secondary mineral ferrihydrite that is formed due to weathering of phyllite. Thus, the ferrihydrite predominates the contributions of the main minerals quartz, muscovite, chlorite, and albite, that are naturally present in the rock material phyllite.
The partitioning of uranium and neptunium onto hydrothermally altered concrete
Authors: Zhao P. , Allen P.G. , Sylwester E.R. , Viani B.E.
Published: August 2006

Partition coefficients (Kd) of U(VI) and Np(V) on untreated and hydrothermally altered concrete were measured in 0.01 M NaCl and 0.01 M NaHCO3 solutions as functions of concentration of the radionuclides, pH, and time. The partition coefficients for both U(VI) and Np(V) on hydrothermally altered concrete are significantly lower than those on untreated concrete. The partition of both U(VI) and Np(V) are pH dependent, although the pH dependence does not appear to reflect precipitation of U and Np-bearing phases. Both sorption and precipitation are likely processes controlling partitioning of U to concrete; sorption is the most likely process controlling the partitioning of Np to concrete. The presence of 0.01 M carbonate species in solution decreases Kd of U(VI) for both hydrothermally altered and untreated concrete from ≥ 104 mL/g to ~400 to 1000 mL/g indicating a significant impact on U(VI) sorption. In contrast, the presence of carbonate only reduced the Kdof Np(V) by one order of magnitude or less. X-ray absorption spectroscopy analysis of U/concrete mixtures at different pHs and times indicate that uranyl ions are partitioned as monomeric species on untreated concrete, but oligomeric species on hydrothermally altered concrete. Similar analysis of Np/concrete mixtures shows that about half of the partitioned Np(V) is reduced to Np(IV) over a period of 6 months.
Applications of NAA, PIXE and XPS for the quantification and characterization of the humic substances/iodine association
Authors: Mercier F. , Moulin Valérie , Guittet M.J. , Barré N. , Toulhoat N. , Gautier-Soyer M. , Toulhoat P.
Published: August 2006

This paper illustrates the coupling of Neutron Activation Analysis (NAA), Proton Induced X-ray Emission (PIXE) and X-ray Photoelectron Spectroscopy (XPS) to quantify iodine contents in natural humic substances from different geochemical origins and to determine its chemical environment. Non negligible contents of iodine from some hundreds of μg/g to more than one weight per cent have been quantified in the humic substances, and iodine seems to be attached to the organic matter by covalent bonds.