Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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35174 Publications

IFW-Dresden – anwendungsorientierte Grundlagenforschung und Sicherheit

Joehnk, P.

  • Lecture (others)
    Verband Deutscher Sicherheitsingenieure (VDSI), Fachgruppe Hochschulen und wissenschaftliche Institutionen, Arbeitskreis Sachsen, 25.10.2000, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19016
Publ.-Id: 19016


Dipole strength in Xe-Isotopes

Massarczyk, R.; Schwengner, R.; Dönau, F.; Anders, M.; Bemmerer, D.; Beyer, R.; Bhatia, C.; Birgersson, E.; Butterling, M.; Elekes, Z.; Ferrari, A.; Hannaske, R.; Junghans, A. R.; Kempe, M.; Kelley, J. H.; Kögler, T.; Matic, A.; Menzel, M. L.; Müller, S.; Reinhardt, T.; Röder, M.; Rusev, G.; Schilling, K. D.; Schmidt, K.; Schramm, G.; Tonchev, A. P.; Tornow, W.; Wagner, A.

Nuclear resonance fluorescence experiments have been performed at the bremsstrahlung facility of the ELBE accelerator in Dresden-Rossendorf. The electromagnetic dipole strength below the neutron separation energy of several nuclei in the chain of Xenon isotopes has been investigated.
The measurements in chain of gaseous isotopes allowed a comparison of the summed strength not only as a function of the neutron-to-proton ratio but also of the nuclear quadrupole deformation.
Experiments and calculations using a quasiparticle random-phase approximation have been used in the chain of Xenon isotopes to estimate the importance nuclear deformation in the energy region on the pygmy strength.

Keywords: nuclear resonance flourescence; nuclear structure; pygmy strength; photo absorption; nuclear deformation

  • Lecture (Conference)
    International Conference on Nuclear Data for Science and Technology 2013, 04.-08.03.2013, New York, USA
  • Lecture (Conference)
    4th Workshop on Nuclear Level Density and Gamma Strength, 27.-31.05.2013, Oslo, Norwegen
  • Contribution to proceedings
    International Conference on Nuclear Data for Science and Technology 2013, 04.-08.03.2013, New York, USA
    DOI: 10.1016/j.nds.2014.08.087
  • Lecture (Conference)
    ERINDA Workshop 2013, 01.-03.10.2013, Genf, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-19015
Publ.-Id: 19015


EASY – ein integriertes elektronisches Antragssystem für öffentliche Fördermittel in Deutschland

Joehnk, P.; Bernhardt, M.; Moravcik, O.; Ducky, M.; Petrik, D.

  • Contribution to proceedings
    CO-MAT-TECH 2000, 19.-20.10.2000, Trnava, Slowakei
    Proceedings of CO-MAT-TECH 2000: Slovenská Technická Univerzita v Bratislave, 121-126

Permalink: https://www.hzdr.de/publications/Publ-19014
Publ.-Id: 19014


Radiopharmacological characterisation of an 18F-labelled azadipeptide nitrile as novel probe for molecular imaging of the tumour-associated cathepsin activity

Löser, R.; Bergmann, R.; Frizler, M.; Mosch, B.; Steinbach, J.; Gütschow, M.; Pietzsch, J.

Objectives: The molecular processes leading to tumour invasion and metastasis are closely associated with a network of intra- and extracellular proteolysis. A prominent role in this network was assigned to the thioldependent cathepsins [1]. Among this class of cysteine proteases, the involvement in tumour pathology could be confirmed for the cathepsins L, S, B, and K.
Due to the vital role of these enzymes in tumour biology, molecular probes that enable their functional imaging in vivo by PET are highly desirable. To this end, an inhibitor of the azadipeptide nitrile chemotype [2] labelled with fluorine-18 was developed. Its radiopharmacological characterisation in normal and tumour-bearing animals to evaluate its potential for PET imaging was the objective of this study.
Methods: Compound 1 (Figure 1A) could be reliably prepared in its 18F-labelled version in a one-pot, two-step process from the corresponding compound bearing the free hydroxy group with intermediary 2-[18F]fluoroethyl nosylate. Its high affinity to the cathepsins L, S, B, and K is reflected by inhibition constants ranging from 0.17 nM (cathepsin K) to 2.4 nM (cathepsin B). The radiopharmacological behaviour of [18F]1 in normal rats was studied in vitro investigating its stability in rat blood, ex vivo by determining its biodistribution and metabolite analysis as well as in vivo by dynamic PET imaging. To evaluate the potential of [18F]1 for imaging of the tumour-associated cathepsin activity its fate in nude mice bearing the tumours derived from the human alveolar carcinoma cell line NCI-H292 was followed with dynamic PET. The expression of the target enzymes in these tumours was studied by immunohistochemistry.
Results: Biodistribution data for [18F]1 after 60 min indicated that renal filtration is the main elimination pathway. Another large part is remaining in the blood, which is obvious from dynamic PET imaging as well (Figure 1B).
This could be partly attributed to the reaction of [18F]1 with glutathione in the blood. The glutathione conjugate of [18F]1 can be also found in the urine and the gut besides the corresponding cysteine conjugate.
Evaluation of the kinetics of [18F]1 in NCI-H292 tumour bearing nude mice revealed its accumulation in the tumours with tumour to muscle ratios up to 10 after 2 h (not shown here) which indicates a specific tumour uptake.
This conclusion is further supported by the fact that all four cathepsins could be detected immunohistochemically in the tumour sections.
Conclusions: The in vivo behaviour of [18F]1 could be well characterised in normal rats as well as in NCI-H292 tumour mice. Despite suboptimal pharmacokinetics due to its inherent thiol reactivity, [18F]1 has the potential for imaging the tumour-associated cathepsin activity, which will be confirmed in further studies.
References: [1] Mason SD, et al. (2011) Trends Cell Biol, 21, 228-37.
[2] Löser R, et al. (2008) Angew Chem Int Ed, 47, 4331-4.

  • Poster
    20th International Symposium on Radiopharmaceutical Sciences (ISRS), 12.-17.05.2013, Jeju, Korea
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals 56(2013), S390
    DOI: 10.1002/jlcr.3058

Permalink: https://www.hzdr.de/publications/Publ-19013
Publ.-Id: 19013


Entwicklung und Realisierung eines projektorientierten integrierten Finanzsystems für Forschungsinstitute

Joehnk, P.; Runow, A.; Sablik, J.

  • Contribution to proceedings
    CO-MAT-TECH 2000, 19.-20.10.2000, Trnava, Slowakei
    Proceedings of CO-MAT-TECH 2000, 127-138

Permalink: https://www.hzdr.de/publications/Publ-19012
Publ.-Id: 19012


Synthesis and radiopharmacological characterization of radiolabeled EGFR-specific oligopeptides

Starke, F.; Sihver, W.; Heldt, J.-M.; Sachse, S.; Bergmann, R.; Pietzsch, H.-J.; Steinbach, J.

Objectives: The epidermal growth factor receptor (EGFR) is overexpressed in many types of human epithelial cancers. Because of its important role in the initiation and progression of tumors, it is an interesting molecular target for new radiotracers. [1] Recently, two short peptides for targeting the EGFR have been reported - the D4 peptide (sequence: LARLLT) and the GE11 peptide (sequence: YHWYGYTPQNVI).[2,3] These short oligopeptides should provide a high specific binding to EGFR-positive tumor cells as well as a rapid tumor uptake and fast blood clearance. We investigated the chemical modification and radiolabeling of the two peptides and examined the application of the D4 peptide as a possible agent for diagnosis and therapy of cancer.
Methods: The D4 and the GE11 peptide haven been conjugated with several chelators, e.g. NOTA, DOTA and HYNIC, to allow radiolabeling with suitable radionuclides for diagnostic (e.g. 99mTc, 64Cu) or for therapeutic applications (e.g. 90Y). The properties of the conjugates were modified by the previous insertion of the newly developed hydrophilic, heterobifunctional linker 1. Toxicity tests have been made using a cell viability assay MTS on the EGFR-expressing cell lines A431 (epidermoid carcinoma cells) and FaDu (squamous carcinoma cells). Binding assays were performed on membranes of A431-, FaDu- and non-EGFR-expressing MDA-MB435S cells.
Kinetics and saturation assays were conducted using the 64Cu-labeled conjugate 2. First biodistribution PET studies in nude mice have been performed.
Results: Conjugation of the two peptides with the new linker 1 followed by the reaction with different chelators gave overall yields of 40-65%. The GE11 peptide itself, as well as all of its conjugates which did not contain the hydrophilic linker 1, were not soluble in water and therefore inapplicable for further experiments. The remaining compounds were labeled with 64Cu and 68Ga (NOTA conjugates), 99mTc (HYNIC conjugates) and 90Y (DOTA conjugates) with specific activities of up to 980 GBq/μmol for 64Cu-2. No change of cell viability was observed after treating A431 and FaDu cells with plain D4 and D4-1 for 4 days at concentrations of up to 125 μM. Binding association with 64Cu-2 on A431 membranes reached equilibrium after one hour, on FaDu membranes equilibrium was not complete after two hours. TDiss½ was less than 5 min. In saturation assays, the affinity determination of 64Cu-2 on A431 and FaDu membranes gave Kd values of 28 ± 6 nM and 72 ± 18 nM, respectively. No specific binding of 64Cu-2 to MDA-MB453S cell membranes was observed. First PET studies with healthy nude mice showed a favorable biodistribution.
Conclusions: We successfully prepared and radiolabeled several conjugates of the EGFR-affine peptides D4 and GE11 with satisfying yields and high specific activities. The insertion of the new hydrophilic heterobifunctional linker 1 was necessary to achieve high solubility in water. The preservation of cell viability after D4 and D4-1 treatment indicates no toxic effect of the conjugates. The affinity of 64Cu-2 to the high EGFR-expressing A431 cells and the moderate EGFR-expressing FaDu cells was in the expected range. Binding assays with radiolabeled GE11-conjugates as well as PET studies of GE11-conjugates and 64Cu-2 with tumor-bearing nude mice are currently under investigation.
References: [1] Cardo-Vila M, et al. (2010) Proc Natl Acad Sci USA, 107, 5118-23.
[2] Song S, et al. (2009) FASEB, 23, 1396-404.
[3] Li Z, et al. (2005) FASEB, 19, 1978-85.

  • Poster
    20th International Symposium on Radiopharmaceutical Sciences, 12.-17.05.2013, Jeju, Korea
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals (2013)56, S374
    DOI: 10.1002/jlcr.3058

Permalink: https://www.hzdr.de/publications/Publ-19011
Publ.-Id: 19011


[18F]Fluorocyclobutyl group: sulfonate leaving group effect on the [18F]fluoride incorporation and subsequent alkylation reaction.

Graham, K.; Kniess, T.; Steinbach, J.; Friebe, M.; Dinkelborg, L. M.; Frank, D.

Objectives: The use of the [18F]cyclobutyl group as a potentially metabolic stable surrogate group for [18F]fluoroalkyl groups has been notified [1-3]. The radiolabeling of a cis-1,3-cyclobutanediol bis-toluenesulfonate
precursor and its conjugation to L-Tyrosine were reported with an overall yield of 8%±5.5 (n = 14, decay corrected). The aim of this work was to improve upon the yield by synthesizing various precursors with different sulfonate leaving groups and evaluating them for their ability to incorporate [18F]fluoride to form the 3-[18F]fluorocyclobutan-1-ol sulfonate 2. Furthermore the effect of these leaving groups on the conjugation reaction of 2 with L-Tyrosine to give the 3-[18F]fluorocyclobutyl-L-tyrosine ([18F]FCBT) should be assessed.
Methods: Various symmetrical cis-1,3-cyclobutanediol bis-sulfonates 1 were synthesized with the different commonly-used sulfonate leaving groups, i.e. tosylate, mesylate, triflate, nosylate and 3,4-dibromobenzenesulfonate. These precursors were subjected to n.c.a. nucleophilic radiofluorination. The 18F-labeled intermediates 2 were purified and the alkylation reaction with L-Tyrosine under standard conditions was tested to assess their conversion to [18F]FBCT.
Results: The cis-1,3-cyclobutanediol bis-sulfonates 1 were synthesized from the cis-1,3-cyclobutanediol using standard methodologies [3]. The triflate derivative was found to be unstable on storage and was eliminated from further evaluation. The radiofluorination of the tosylate (65%) and 3,4-dibromobenzenesulfonate (58%) precursors resulted in better [18F]fluoride incorporation than mesylate (30%) and nosylate (5%). The subsequent alkylation of the purified intermediates 2 with L-Tyrosine showed the same trend with 82% yield for tosylate and 69% yield for 2,3-dibromobenzenesulfonate () whereas mesylate gave only 4% yield and nosylate failed to give product.
Conclusions: By a systematic evaluation of different sulfonate leaving groups of the symmetrical cis-1,3-cyclobutanediol bis-sulfonates 1 and the conjugation of the resulting intermediate 2 with L-Tyrosine it was clearly demonstrated that tosylate and 3,4-dibromobenzenesulfonate are more favorable than mesylate and nosylate.
Acknowledgements: We gratefully acknowledge Selahattin Ede and Mario Mandau for technical assistance.
References: [1] Franck D, et al. (2011) J Nucl Med, 52, Suppl. 1, 168P. [2] Franck D, et al. (2011) J Label Compd
Radiopharm, 54, Suppl. 1, S447. [3] Franck D, et al. (2013) Bioorg Med Chem, 21, 643-52.

  • Poster
    20th International Symposium on Radiopharmaceutical Sciences, 12.-17.05.2013, Jeju, Korea
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals (2013)56, S134

Permalink: https://www.hzdr.de/publications/Publ-19010
Publ.-Id: 19010


Radioaktiv belastete Umwelt – Lebensräume für Bakterien?

Zirnstein, I.

Ob im Packeis, in der staubtrockenen Wüste, in Salzseen oder in sauren Halden – Bakterien und andere Kleinstlebewesen besiedeln alle Lebensräume. So leben sie auch in Schwermetall-belasteten und radioaktiv-kontaminierten Milieus z.B. in ehemaligen Uran-Bergwerken. Ihr Überleben in solchen extremen Umgebungen kann bei der Reinigung von Abwässern oder der Gewinnung von Rohstoffen sogar für den Menschen nützlich sein.

  • Lecture (others)
    11.Lange Nacht der Wissenschaften 2013, 05.07.2013, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19009
Publ.-Id: 19009


Affinity of yttrium-90 labeled anti-EGFR antibody cetuximab to head and neck squamous cell carcinoma (HNSCC) xenografts, compared to the response to combined external and internal irradiation

Sihver, W.; Koi, L.; Brüchner, K.; Heldt, J.-M.; Bergmann, R.; Pietzsch, H.-J.; Pietzsch, J.; Steinbach, J.; Zips, D.; Baumann, M.

Objectives: Since the epidermal growth factor receptor (EGFR) is often overexpressed in HNSCCs, there is strong interest to inhibit the growth of these tumor entities via the EGFR. Thus, in this study pharmacological parameters (Ki and Bmax) of the chimeric monoclonal anti-EGFR antibody cetuximab (C225), conjugated with the bifunctional chelator (BFC) CHX-A’’-DTPA (C1), labeled with the therapeutic radionuclide yttrium-90 were determined in three different HNSCC cell lines, whose EGFR expression was also estimated. Furthermore, nude mice bearing xenografts generated from these three HNSCC cells were studied in order to investigate whether internal irradiation with the radiolabeled antibody conjugate could improve the results of external irradiation alone.
Methods: C1 was conjugated to C225 via thiourea bridging. MALDI-TOF-MS revealed a BFC to C225 ratio of 4 to 1. The affinity of the yttrium-90 labeled conjugate C1-C225 was determined using membranes of the HNSCC cell lines FaDu, UT-SCC-5 and UT-SCC-8. The EGFR expression was determined by Western blotting. The tumor models were created by s.c. transplantation of pieces from the investigated tumor lines into the hind leg of nude mice (NMRI nu/nu). Different experimental groups were treated by either [90Y]C1-C225 alone, C225 alone, external irradiation alone, external irradiation plus unlabeled C225 or external irradiation plus [90Y]C1-C225.
Results: [90Y]C1-C225 was routinely prepared with high specific activity (about 8 GBq/mg) and showed high affinity with Kd values in the low nanomolar range and a maximal number of binding sites (Bmax) of 4.0, 4.9 and 10.4 pmol/mg in membranes of FaDu, UT-SCC-5 and UT-SCC-8 cells, respectively. In vitro the EFGR expression in these cell lines correlated well with the corresponding Bmax values. In vivo the HNSCC tumors showed a different response to [90Y]C1-C225 alone compared to unlabeled C225 receiving a specific tumor growth delay of 4.2, 0.07 and 3.7 for FaDu, UT-SCC-5 and UT-SCC-8. In FaDu the tumor control dose (TCD50) was significantly decreased after external irradiation in combination with internal irradiation. In contrast to the effect in FaDu no change of the TCD50 was observed in UT-SCC-5.
Conclusions: For [90Y]C1-C225 a high affinity was determined in membranes of three different HNSCC cell lines and the Bmax values correlated with the EGFR expression in vitro. Furthermore, in different HNSCC different responses to treatment were observed. However, the intertumoral heterogeneity did not correlate with the Bmax values, thus it seems that additional factors influence the response to internal irradiation.
Acknowledgements: Supported by 02NUK006A+B (Kompetenzverbund Strahlenforschung, KVSF)

  • Lecture (Conference)
    20th International Symposium on Radiopharmaceutical Sciences (ISRS), 12.-17.05.2013, Jeju, Korea
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals 56(2013), S41

Permalink: https://www.hzdr.de/publications/Publ-19008
Publ.-Id: 19008


Optimization of Pentadentate Bispidines as Bifunctional Chelators for 64Cu Positron Emission Tomography (PET)

Comba, P.; Hunoldt, S.; Morgen, M.; Pietzsch, J.; Stephan, H.; Wadepohl, H.

Pentadentate bispidine ligands (3,7-diazabicyclo[3.3.1]nonanes) are optimized for maximum complex stability and facile functionalization with respect to their coupling to biological vector molecules and/or fluorescence markers for PET (positron emission tomography) and multimodal imaging (i.e., PET and optical imaging). The pentadentate ligand with two tertiary amine donors, two p-methoxy substituted pyridines, and one unsubsituted pyridine group is shown to best fulfill important conditions for PET applications, i.e., fast complexation with CuII and high in vivo stability, and this was predicted from the solution chemistry, in particular the CuII/I redox potentials. Also, solvent partition experiments to model the lipophilicity of the CuII complexes indicate that the bis p-methoxy substituted ligand leads to cationic complexes with an appreciable lipophilicity. This is supported by the biodistribution experiments that show that the complex with the p-methoxy substituted ligand is excreted very quickly and primarily via the renal route and therefore is ideally suited for the development of PET tracers with ligands of this type coupled to biomolecules.

Permalink: https://www.hzdr.de/publications/Publ-19007
Publ.-Id: 19007


Strong-field THz spectroscopy of low-dimensional semiconductor systems

Helm, M.

Many low-energy excitations in solids fall into the meV or THz range. Whereas linear spectroscopy is a valuable tool to obtain information on the linear response of these excitations, recent progress in THz sources also enables one to access their nonlinear and time-resolved behavior. To this end we use a free-electron laser to study intraexcitonic transitions in quantum wells and carrier dynamics in graphene.
Excitons possess a hydrogen-like internal excitation spectrum with a characteristic energy scale in the THz range. We pump the 1s-2p intraexcitonic transition in GaAs and InGaAs multiquantum wells with a THz free-electron laser and probe the induced changes in the absorption spectrum via interband absorption using a near-infrared femtosecond laser. We observe a splitting of the 1s exciton line, which can be explained by the Autler-Townes or AC Stark effect [1]. The behavior is, however, much more complex than for an ideal two-level system. Since for electric fields in the 10 kV/cm range the Rabi energy is of the same order of magnitude as the 1s-2p transition energy, we are in fact clearly beyond the validity of the rotating wave approximation. At the highest fields, when also the ponderomotive energy (e2F2/4mw2) approaches the exciton binding energy, signatures of exciton field ionization are observed.
In graphene with its vanishing bandgap, interband excitations extend down to very low frequencies, where they compete with the free-carrier (intraband) absorption in lightly doped graphene (EF=13 meV). We have performed THz pump-probe experiments on multilayer graphene over a wide range of photon energies (10-250 meV) to investigate the carrier dynamics. Interestingly we observe a crossover from induced transmission (bleaching) for hw > 2EF to induced absorption for hw < 2EF. At these photon energies interband transitions are initially blocked, but become possible after intraband free-carrier absorption and heating [2]. In a magnetic field the bands split up into non-equidistant Landau levels, which can be pumped and probed selectively. Using left- and right-circularly polarized light reveals some surprising behavior related to the importance of Auger scattering.

Keywords: excitons; quantum well; free-electron laser; terahertz; graphene

  • Invited lecture (Conferences)
    20th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-20), 01.-05.07.2013, Wroclaw, Polen

Permalink: https://www.hzdr.de/publications/Publ-19006
Publ.-Id: 19006


Apatite and Clinopyroxene as Tracers for Metasomatic Processes in Nepheline clinopyroxenites of Uralian-Alaskan-Type Complexes in the Ural Mountains, Russian Federation

Krause, J.; Harlov, D. E.; Pushkarev, E. V.; Brügmann, G. E.

Clinopyroxene and apatite are found to trace metasomatic processes in nepheline-bearing clinopyroxenites (tilaites) from the igneous, mafic-ultramafic Uralian-Alaskan-type complexes of Kytlym and Nizhny Tagil, Ural Mountains, Russian Federation. The clinopyroxenites consist predominantly of coarse-grained, partially to totally altered clinopyroxene phenocrysts in a matrix of fine-grained olivine, clinopyroxene, plagioclase, K-feldspar, and nepheline. Apatite occurs as idiomorphic inclusions (< 25 µm) in the clinopyroxene and as xenomorphic grains in the matrix.
In the matrix, plagioclase is partially to totally replaced by a fine-grained symplectitic intergrowth of K-feldspar and nepheline most likely due to the influx of an K2O-, Na2O-, and Al2O3-bearing fluid. During conversion of the plagioclase, CaO and SiO2 were partitioned into the fluid. Altered areas in the clinopyroxene phenocrysts are characterized by the redistribution of major and trace elements. This includes depletion in Mg, Rb, and Sr and enrichment in Al, Na, Ba, U, Th, REE except Eu, and HFSE compared to the original magmatic areas in the clinopyroxene. Apatite inclusions in the altered areas of the clinopyroxene and in the matrix are enriched in Cl relative to apatite inclusions in the unaltered areas of clinopyroxene.
It is proposed that these rocks experienced a two-stage metasomatic process. Stage 1 was the partial to total alteration of plagioclase to K-feldspar and nepheline due to interaction with an infiltrating (K,Na)Cl-rich brine (most likely late magmatic) with an Al component, which enriched the fluid in CaCl2. Stage 2 consisted of the partial to total chemical alteration of the original magmatic clinopyroxene by this now CaCl2-enriched fluid through the mechanism of coupled dissolution-reprecipitation. This process also chemically altered the apatite inclusions from fluor-chlorapatite to chlor-fluorapatite and redistributed as well as partially removed the titanomagnetite inclusions in the altered areas. This is supported experimentally by the fact that alteration of fluorapatite to Cl-rich apatite can only take place in the presence of CaCl2-bearing fluids and by the fact that in general Fe and Ti, along with most metal cations, are relatively mobile in Cl-rich fluids.
If this scenario is correct, the implications from this study are that inclusions of one mineral in a host mineral can be chemically overprinted during metasomatic alteration of the host mineral. While at the same time the original crystal shape and orientation of both the host phase as well as that of the inclusions are preserved.

Keywords: Fluor-chlorapatite; Clinopyroxene; Metasomatism; Coupled dissolution-reprecipitation; Uralian-Alaskan-type complexes

Permalink: https://www.hzdr.de/publications/Publ-19005
Publ.-Id: 19005


AMS measurements of cosmogenic and supernova-ejected radionuclides in deep-sea sediment cores

Feige, J.; Wallner, A.; Fifield, L. K.; Korschinek, G.; Merchel, S.; Rugel, G.; Steier, P.; Winkler, S. R.

Samples of two deep-sea sediment cores from the Indian Ocean are analyzed with accelerator mass spectrometry (AMS) to search for traces of recent supernova activity ∼2 Myr ago. Here, long-lived radionuclides, which are synthesized in massive stars and ejected in supernova explosions, namely 26Al, 53Mn and 60Fe, are extracted from the sediment samples. The cosmogenic isotope 10Be, which is mainly produced in the Earth’s atmosphere, is analyzed for dating purposes of the marine sediment cores. The first AMS measurement results for 10Be and 26Al are presented, which represent for the first time a detailed study in the time period of 1.7-3.1 Myr with high time resolution. Our first results do not support a significant extraterrestrial signal of 26Al above terrestrial background. However, there is evidence that, like 10Be, 26Al might be a valuable isotope for dating of deep-sea sediment cores for the past few million years.

Keywords: accelerator mass spectrometry; dating; deep-sea Sediment; supernova; astrophysics; cosmogenic; radionuclide

Permalink: https://www.hzdr.de/publications/Publ-19004
Publ.-Id: 19004


Ressourcentechnologien "Made in Germany" - bisherige Entwicklung und Perspektiven des Helmholtz-Instituts Freiberg

Gutzmer, J.; van den Boogaart, K. G.; Klossek, A.

Motivated by the steadily increasing global demand for metalliferous resources – as expressed by increasing prices and protective measures by resource-rich countries - the Helmholtz Institute Freiberg for Resource Technology was established in 2011 with the objective to develop technologies for the energy- and resource efficient as well as environmentally benign production and recycling of metalliferous raw materials. The HIF belongs to Helmholtz-Zentrum Dresden-Rossendorf and is being established in close cooperation with the TU Bergakademie Freiberg. Metalliferous raw materials needed for the renewable energy sector, including the rare earth elements, indium, germanium and gallium, define the research focus of the Helmholtz-Institute as the rapidly increasing global demand for these metals needs to be urgently met by technological development. Research is carried out in close collaboration with partners from industry and academia in regional, national and international consortia. The Helmholtz-Institute also aims to make a relevant contribution to the education of a new generation of highly qualified academic and technical staff for German industry and academia.

Keywords: resource technology

  • Book chapter
    A. Sroka: Schriftenreihe des Instituts für Markscheidewesen und Geodäsie an der TU Bergakademie Freiberg, Freiberg: Wagner Digitaldruck und Medien, 2013, 978-3-938390-10-8, 1-5

Permalink: https://www.hzdr.de/publications/Publ-19003
Publ.-Id: 19003


Röntgentomographische Untersuchung von Blasengeschwindigkeiten in vertikalen gas-flüssig Strömungen

Banowski, M.; Patmonoaji, A.; Lucas, D.; Hampel, U.

Die Entwicklung von neuen Zweiphasen-CFD-Modellen zur Berechnung von komplexen Strömungsvorgängen stellen ein wichtiges Ziel für Industrie und Forschung dar. Um neue Modelle sorgfältig validieren zu können, werden experimentelle quantitative Daten entsprechender Strömungsformen mit hohen zeitlichen und räumlichen Auflösungen benötigt. An der TOPFLOW-Versuchsanlage des HZDR werden dazu umfangreiche Versuche an einer vertikalen DN50-Testsektion mit Luft-Wasser und Dampf-Wasser-Strömungen bis zu p = 65 bar und einer weiten Variation der Leerrohrgeschwindigkeiten für die Wasser- und die Gasphase durchgeführt. Unter Verwendung der am HZDR entwickelten ultraschnellen Zweiebenenröntgentomographie werden momentane Gasgehaltsverteilungen im Rohrquerschnitt mit Bildraten von bis zu 2500 frames/s, einer Messzeit von 10 s und einer räumlichen Auflösung von ca. 2 mm gemessen. Nach erfolgter Rekonstruktion werden mithilfe von Segmentierungs- und Auswertealgorithmen Einzelblaseninformationen generiert. Diese Daten werden hinsichtlich Strömungsdetails wie Blasengrößenverteilungen, radiale Gasgehalts- und Gasgeschwindigkeitsprofile, Strömungsverhalten von Kleinblasen in Abhängigkeit benachbarter Blasen u. a. weiter analysiert. Der Geschwindigkeitsinformation von Einzelblasen kommt dabei eine zentrale Rolle zu. Um diese bestimmen zu können werden detektierte Blasen aus beiden Tomographieebenen in Größe, Ort und resultierender Geschwindigkeit verglichen, sodass Blasenpaare anhand von Wahrscheinlichkeitswerten für beide Ebenen ermittelt werden. Unter Verwendung des konstruktiven Abstands sowie des zeitlichen Versatzes zwischen beiden Ebenen wird die individuelle Blasengeschwindigkeit errechnet. Neben der Geschwindigkeit in Hauptströmungsrichtung können somit auch radiale Geschwindigkeitskomponenten einer Blase ermittelt werden. Auf Basis der ermittelten Geschwindigkeiten können somit von Ort und Blasengröße abhängige Geschwindigkeitsprofile erstellt werden.
Im Ergebnis stehen analysierte Messdaten mit hohem Informationsgehalt zur Zweiphasen-CFD-Modellvalidierung zur Verfügung. Diese neu generierten Daten werden in diesem Beitrag an verschiedenen Zweiphasenregimen bei aufwärts- sowie abwärtsgerichteten Strömungen vorgestellt und diskutiert. Dazu werden neben quantitativen Ergebnissen auch qualitative Untersuchungsergebnisse von Geschwindigkeitsfeldern präsentiert.

Keywords: two-phase flow; bubble velocity

  • Abstract in refereed journal
    Chemie Ingenieur Technik 85(2013)9, 1423
    DOI: 10.1002/cite.201250642
  • Lecture (Conference)
    ProcessNet Jahrestreffen der Fachgemeinschaft Fluiddynamik und Trenntechnik, 25.-27.09.2013, Würzburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19002
Publ.-Id: 19002


Segmentation of ultrafast X-ray tomographed gas-liquid flows in a vertical pipe at different flow regimes

Banowski, M.; Lucas, D.; Hoppe, D.; Beyer, M.; Szalinski, L.; Hampel, U.

At the Institute of Fluid Dynamics at the Helmholtz-Zentrum Dresden-Rossendorf the ultrafast electron beam X-ray computed tomography was developed in the last years to investigate two-phase flows. The tomography system works according to the scanned electron beam principle. In a recent study we investigated different gas-liquid flow regimes in a vertical pipe test rig at the TOPFLOW thermal hydraulic test facility. The study contains experiments of gas-liquid flow regimes varied with different superficial velocities for both phases and different flow directions. The obtained data is required for understanding fundamental physics of flow phenomena and for improving and validating of models for flow simulation codes.
To extract the needed data from the 3D gray value array, a new segmentation algorithm is developed. This algorithm bases on bubble detection by pixel agglomeration. The results are compared with threshold and gradient methods using two different bubble phantoms and real two-phase flow measurements. The new algorithm shows the best qualitative and quantitative results.

Keywords: X-ray; computed tomography; gas-liquid flow; segmentation

  • Open Access Logo Contribution to proceedings
    7th World Congress on Industrial Process Tomography (WCIPT), 02.-05.09.2013, Krakow, Polska
  • Poster
    7th World Congress on Industrial Process Tomography (WCIPT), 02.-05.09.2013, Krakow, Polska

Permalink: https://www.hzdr.de/publications/Publ-19001
Publ.-Id: 19001


Die Bedeutung der Materialwissenschaften für die zukünftige gesellschaftliche Entwicklung

Joehnk, P.

  • Lecture (Conference)
    Plenarvortrag, CO-MAT-TECH 2000, 19.-20.10.2000, Trnava, Slowakei

Permalink: https://www.hzdr.de/publications/Publ-19000
Publ.-Id: 19000


EASY – elektronicky system na vypracovanie ziadosti o grantove prostriedky

Joehnk, P.; Moravcik, O.; Schreiber, P.; Ducky, M.; Petrik, D.

  • ATP - Administrative Theory & Praxis 7(2000)12, 56-57

Permalink: https://www.hzdr.de/publications/Publ-18999
Publ.-Id: 18999


Entwicklung einer betriebswirtschaftlichen Gesamtlösung für Forschungseinrichtungen

Joehnk, P.

  • Lecture (others)
    Vortrag DV-Ausschuss der WGL, 27.06.2000, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18998
Publ.-Id: 18998


Konzeption und Einsatz moderner DV-Systeme in Forschungseinrichtungen

Joehnk, P.

  • Lecture (others)
    Vortrag Bundesministerium der Finanzen, 08.05.2000, Bonn, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18997
Publ.-Id: 18997


New Publik Management: Neue Steuerungsmodelle in wissenschaftlichen Einrichtungen

Joehnk, P.

  • Lecture (others)
    Doktoranden-Klausur des IFS, 17.04.2000, Jetrichovice, Ceska Republika

Permalink: https://www.hzdr.de/publications/Publ-18996
Publ.-Id: 18996


Neubau-Realisierung

Joehnk, P.

  • Communication & Media Relations
    Broschüre 01.11.1999

Permalink: https://www.hzdr.de/publications/Publ-18995
Publ.-Id: 18995


Personalinformationssystem für den Einsatz in Forschungseinrichtungen

Joehnk, P.; Sablik, J.

  • Lecture (Conference)
    7. Medzinárodná vedecká konferencia CO-MAT-TECH 1999, 19.-20.10.1999, Trnava, Slovenská

Permalink: https://www.hzdr.de/publications/Publ-18994
Publ.-Id: 18994


Betriebswirtschaftliches Gesamtkonzept für Forschungseinrichtungen

Joehnk, P.

  • Lecture (Conference)
    7. Medzinárodná vedecká konferencia CO-MAT-TECH 1999, 19.-20.10.1999, Trnava, Slovenská

Permalink: https://www.hzdr.de/publications/Publ-18993
Publ.-Id: 18993


Flexibilisierung als Herausforderung

Joehnk, P.; Franke, S.

  • Wissenschaftsmanagement 4(1999), 18-24

Permalink: https://www.hzdr.de/publications/Publ-18992
Publ.-Id: 18992


Betriebswirtschaftliche Gesamtlösung für Forschungseinrichtungen unter Berücksichtigung der Kosten- und Leistungsrechnung

Joehnk, P.

  • Lecture (others)
    Praxisseminar, 22.04.1999, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18991
Publ.-Id: 18991


Hydrodynamic characterization of transient multiphase flows in monolithic structures using ultrafast X-ray tomography

Schäfer, T.; Wagner, M.; Hampel, U.; Weiß, M.; Meitzner, C.; Lange, R.

Detailed hydrodynamic characterization of transient multiphase flows is significant in the field of process engineering. The ultrafast X-ray tomography system ROFEX was used to analyze the complex transient multiphase flow and its hydrodynamic characteristics in monolithic structures. Introducing the applied tomography system and the particular experimental set-up, selected experiments and investigations will be explained. Furthermore several methods for the computation and visualization of gas and liquid phase distribution, the calculation of liquid holdup and the characterization of the occurring flow structures will be presented. As a conclusion a selection of achieved results and the derivable information will be summarized.

Keywords: ultrafast X-ray tomography; multi-phase flow; flow structure; flow properties; monolith

  • Contribution to proceedings
    7th World Congress on Industrial Process Tomography, WCIPT7, 02.-05.09.2013, Kraków, Poland
    Proceedings of WCIPT7
  • Lecture (Conference)
    7th World Congress on Industrial Process Tomography, WCIPT7, 02.-05.09.2013, Kraków, Poland

Permalink: https://www.hzdr.de/publications/Publ-18990
Publ.-Id: 18990


Entwurf eines Personalinformationssystems für den Einsatz in Forschungseinrichtungen

Joehnk, P.

  • Other report
    Bratislava: Slowakische Technische Universität in Bratislava, 1999
    83 Seiten

Permalink: https://www.hzdr.de/publications/Publ-18989
Publ.-Id: 18989


Budgetierung, KLR, Zielvereinbarung und Controlling - neue Steuerungselemente für Forschungseinrichtungen

Joehnk, P.

  • Lecture (others)
    Vortrag Forschungszentrum Rossendorf, 10.03.1999, Dresden Rossendorf, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18988
Publ.-Id: 18988


Datenverarbeitung: Ordnung im Reich der Drittmittel

Joehnk, P.

  • WGL-Journal (1997)1, 15

Permalink: https://www.hzdr.de/publications/Publ-18987
Publ.-Id: 18987


Mit der Principal-Agent-Theorie von der Input-Orientierung zur Output-Steuerung

Joehnk, P.

  • Lecture (others)
    Seminarvortrag, 03.-05.03.1999, Holzhau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18986
Publ.-Id: 18986


Ziele und Elemente des neuen Modells der Ressourcensteuerung in Forschungseinrichtungen

Joehnk, P.

  • Lecture (others)
    Seminarvortrag, Gewerkschaft Öffentliche Dienste, Transport und Verkehr, 11.-12.01.1999, Undeloh, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18985
Publ.-Id: 18985


Moderné informacné systémy v správe vedecko-technických grantov na priklade systému PROMAN-W

Joehnk, P.; Moravcik, O.; Michalconok, G. F.; Petrik, D.

  • ATP - Administrative Theory & Praxis (1998)12, 54-55

Permalink: https://www.hzdr.de/publications/Publ-18984
Publ.-Id: 18984


Erfahrungen beim Neubau von Laborgebäuden

Joehnk, P.

  • Lecture (Conference)
    Fachtagung "Arbeitssicherheit in Hochschulen und wissenschaftlichen Institutionen", 18.-20.05.1998, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18983
Publ.-Id: 18983


Berufsperspektiven für Naturwissenschaftler - Realität und Vision

Joehnk, P.

  • Lecture (others)
    Gewerkschaft ÖTV, Schulungszentrum, 01.10.1997, Undeloh, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18982
Publ.-Id: 18982


Moderne DV-Instrumente in der Wissenschaftsadministration am Beispiel von "PROMAN-W"

Joehnk, P.

  • Lecture (others)
    Forschungsforum Leipzig, 01.09.1997, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18981
Publ.-Id: 18981


Konfiguration und Optimierung der Software-Anwendungsentwicklung vom Typ Client-Server für das Management von (Drittmittel-)Projekten

Joehnk, P.; Moravcik, O.; Michalconok, G. F.; Misut, M.

  • Contribution to proceedings
    42. Internationales Wissenschaftliches Kolloquium, 22.-25.09.1997, Illmenau, Deutschland
    Tagungsband 1, 78-83

Permalink: https://www.hzdr.de/publications/Publ-18980
Publ.-Id: 18980


Software-Anwendungsentwicklung vom Typ Klient-Server für das Management von Projekten

Moravcik, O.; Joehnk, P.; Michalconok, G. F.; Misut, M.

  • Contribution to external collection
    in: Wissenschaftliche Berichte der Slowakischen Technischen Universität Bratislava 5, Bratislava: Slowakische Technische Universität Bratislava, 1997, 171-177

Permalink: https://www.hzdr.de/publications/Publ-18979
Publ.-Id: 18979


Moderne Instrumente in der Administration - PROMAN-W: Ein DV-System zum Management von Projekten

Joehnk, P.; Bernhardt, M.

  • Contribution to external collection
    in: IFW Jahresbericht 20, Dresden: IFW, 1997

Permalink: https://www.hzdr.de/publications/Publ-18978
Publ.-Id: 18978


Zuwenden und Fördern - das andere Sponsoring

Joehnk, P.

  • Communication & Media Relations
    Broschüre, Förderverein Gymnasium Coswig 01.11.1996

Permalink: https://www.hzdr.de/publications/Publ-18977
Publ.-Id: 18977


First FEL lasing driven by SRF gun at Rossendorf

Teichert, J.; Xiang, R.; Arnold, A.; Büttig, H.; Justus, M.; Lehnert, U.; Lu, P.; Michel, P.; Murcek, P.; Schurig, R.; Seidel, W.; Vennekate, H.; Will, I.; Rudolph, J.; Kamps, T.

We present in this talk the first experiment of IR-FEL production driven by ELBE SRF gun.

Keywords: free electron laser; SRF gun

  • Invited lecture (Conferences)
    PITZ collaboration meeting 2013, 11.-12.06.2013, DESY, 15738 Zeuthen, Germany

Permalink: https://www.hzdr.de/publications/Publ-18976
Publ.-Id: 18976


Neubau = Zukunft

Joehnk, P.

  • Communication & Media Relations
    Broschüre IFW Dresden 01.11.1996

Permalink: https://www.hzdr.de/publications/Publ-18975
Publ.-Id: 18975


Kosten-Nutzen-Relation in Bezug auf die stärkere Nutzung elektronischer Informationsdienste

Joehnk, P.

  • Lecture (others)
    Workshop "Modernes Informationsmanagement in deutschen Forschungseinrichtungen - Stand und Zukunft", 01.10.1996, Bonn, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18974
Publ.-Id: 18974


Bewirtschaftung von Drittmittelressourcen

Joehnk, P.

  • Lecture (Conference)
    Finanzmanagement und Drittmittelressourcen - Nöte und Chancen der wissenschaftlichen Forschungseinrichtungen, 01.10.1996, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18973
Publ.-Id: 18973


Wir leben von der Substanz / Interview

Joehnk, P.

  • ÖTV-Report Wissenschaft und Forschung (1996)

Permalink: https://www.hzdr.de/publications/Publ-18972
Publ.-Id: 18972


Finanz- und Kostenmanagement am Beispiel der Produktpalette MACH

Joehnk, P.

  • Lecture (others)
    Vortrag, Ministerium der Finanzen, 01.06.1996, Stuttgart, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18971
Publ.-Id: 18971


Festansprache

Joehnk, P.

  • Lecture (others)
    Festansprache aus Anlaß des 10-järigen Jubiläums der Fakultät für Werkstoffe und Technologie Slowakische Technische Universität Bratislava, 01.05.1996, Trnava, Slowakei

Permalink: https://www.hzdr.de/publications/Publ-18970
Publ.-Id: 18970


Vorwort: Hans Gille - ein Wanderer zwischen den Welten?

Joehnk, P.

  • Book chapter
    in: Deutschland - in vier Teilen erlebt, o.A.: Eigen-Verl., 1996

Permalink: https://www.hzdr.de/publications/Publ-18969
Publ.-Id: 18969


Spectroscopic identification of binary and ternary surface complexes of Np(V) on gibbsite

Gückel, K.; Rossberg, A.; Müller, K.; Brendler, V.; Bernhard, G.; Foerstendorf, H.

Detailed molecular information of the Np(V) sorption species on amorphous and crystalline gibbsite were obtained for the first time by in situ time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy under environmentally relevant conditions. The results consistently demonstrate the formation of mononuclear inner sphere complexes of the NpO2+ ion irrespective of the prevailing atmospheric condition. In particular, the impact of the presence of atmospheric equivalent added carbonate on the speciation in solution and on the surfaces becomes evident from vibrational data. Whilst the 1:1 aqueous carbonato species (NpO2CO3−) was found to become predominant in the circumneutral pH range, it is most likely that this species is sorbed onto the gibbsite surface as an inner sphere ternary surface complex where the NpO2+ moiety is directly coordinated to the functional groups of the gibbsite’s surface. These findings are corroborated by results obtained from EXAFS spectroscopy. The identification of the Np(V) surface species on gibbsite constitutes a basic finding for a comprehensive description of the dissemination of neptunium in groundwater systems.

Permalink: https://www.hzdr.de/publications/Publ-18968
Publ.-Id: 18968


Wissenschaftsgemeinschaft Blaue Liste - eine Standortbestimmung

Joehnk, P.

  • Lecture (others)
    Klausurtagung der Mitglieder des Stadtrates Dresden, 01.04.1996, Bad Schandau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18967
Publ.-Id: 18967


Kosten-/Leistungsrechnung, Controlling und Berichtswesen in Ministerien und oberen Bundesbehörden

Joehnk, P.

  • Lecture (others)
    Software-Praxistag, 01.03.1996, Bonn, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18966
Publ.-Id: 18966


Wie sind Mitarbeiter einer Forschungseinrichtung motivierbar?

Joehnk, P.

  • Lecture (others)
    Vortrag, 20.02.1996, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18965
Publ.-Id: 18965


Finanzbuchhaltung und Controlling-Instrumente unter Windows

Joehnk, P.

  • Lecture (others)
    Fachinformationszentrum Karlsruhe, 30.11.1995, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18964
Publ.-Id: 18964


Virtuelle Bibliotheken - Handlungsbedarf für die Wissenschaftsgemeinschaft Blaue Liste?

Joehnk, P.

  • Lecture (others)
    Verwaltungsausschuss der WBL, 02.05.1995, Greifswald, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18963
Publ.-Id: 18963


Einführung eines integrierten Finanz- und Kostenmanagement-Systems

Joehnk, P.

  • Lecture (others)
    Gesellschaft für Mathematik und Datenverarbeitung, Projektträger Fachinformation, 09.10.1994, Darmstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18962
Publ.-Id: 18962


Standortbestimmung des IFW Dresden

Joehnk, P.

  • Lecture (others)
    Vortraf, 31.03.1994, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18961
Publ.-Id: 18961


Praxis der Projektförderung des Sächsischen Ministers für Umwelt und Landwirtschaft

Joehnk, P.

  • Lecture (others)
    Seminar für Ministeriumsmitarbeiter und Projektträger, 23.-27.03.1992, Bad Schandau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18960
Publ.-Id: 18960


Einführungsseminar für Projektträger

Joehnk, P.

  • Lecture (others)
    Seminarvortrag, Einführungsseminar für Projektträger, 30.09.-02.10.1991, Boppard, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18959
Publ.-Id: 18959


Projektförderung des BMFT auf Kostenbasis

Joehnk, P.; Donau, J. J.; Schneider, G.

  • Book (Authorship)
    St. Augustin: Joehnk-Stadelmayer, 1991
    278 Seiten

Permalink: https://www.hzdr.de/publications/Publ-18958
Publ.-Id: 18958


Einführungsseminar füe neue Mitarbeiter bei Projektträgern des BMFT

Joehnk, P.

  • Lecture (others)
    Seminarvortrag bei Projektträgern des BMFT, 11.-14.03.1991, Winterscheid, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18957
Publ.-Id: 18957


Der Umwelt im sächsischen Raum gemeinsam schnell und wirksam helfen

Joehnk, P.

  • Dresdner Universitätsjournal (1991)2

Permalink: https://www.hzdr.de/publications/Publ-18956
Publ.-Id: 18956


Näher den Kunden im Osten

Joehnk, P.

  • KfK-Hausmitteilungen (1991)

Permalink: https://www.hzdr.de/publications/Publ-18955
Publ.-Id: 18955


Posterbeitrag Gewässerschutzseminar

Joehnk, P.; Knobel, K.-P.

  • Poster
    Magdeburger Gewässerschutzseminar, 28.-30.11.1990, Magdeburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18954
Publ.-Id: 18954


Einführungsseminar für neue Mitarbeiter bei der VDI/VDE

Joehnk, P.

  • Lecture (others)
    Seminar bei der VDI/VDE, 29.-31.10.1990, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18953
Publ.-Id: 18953


Posterpräsentation Umweltforschung

Joehnk, P.; Robel, W.

  • Poster
    Deutsch-deutsches Symposium Umweltforschung in der DDR, 01.09.1990, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18952
Publ.-Id: 18952


Seminarvortrag

Joehnk, P.

  • Lecture (others)
    Bundesakademie für öffentliche Verwaltung , Projektgruppe Fortbildung DDR (für Minister und Staatsekretäre der DDR), 21.-25.05.1990, Boppard, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18951
Publ.-Id: 18951


Jahresbericht 1989 des Projektträgers des BMFT für Wassertechnologie, Abwasser- und Schlammbehandlung

Joehnk, P.; (Editor)

  • Other report
    Karlsruhe: Kernforschungszentrum Karlsruhe, 1990
    137 Seiten

Permalink: https://www.hzdr.de/publications/Publ-18950
Publ.-Id: 18950


Praxis der Projektförderung des Bundesministeriums für Forschung und Technologie

Joehnk, P.; Vollmer, S.

  • Other report
    Karlsruhe: Kernforschungszentrum Karlsruhe, 1989
    169 Seiten

Permalink: https://www.hzdr.de/publications/Publ-18949
Publ.-Id: 18949


Einführungsseminar für neue PT-Mitarbeiter

Joehnk, P.

  • Lecture (others)
    Seminarvortrag BMFT, 29.05.-01.06.1989, Winterscheid, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18948
Publ.-Id: 18948


Die Projektförderung des Bundesministeriums für Forschung und Technologie - eine Darstellung der finanziellen, rechtlichen, administrativen und organisatorischen Rahmenbedingungen

Joehnk, P.

  • Lecture (others)
    Industrie- und Handelskammer Mannheim, 01.08.1988, Mannheim, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18947
Publ.-Id: 18947


Die Information als wichtigster Produktionsfaktor

Joehnk, P.

  • Markt & Technik 20(1986)

Permalink: https://www.hzdr.de/publications/Publ-18946
Publ.-Id: 18946


Sponge-like Si-SiO2 nanocomposite – morphology studies of spinodally decomposed silicon-rich oxide

Friedrich, D.; Schmidt, B.; Heinig, K. H.; Liedke, B.; Mücklich, A.; Hübner, R.; Wolf, D.; Kölling, S.; Mikolajik, T.

Sponge-like Si nanostructures embedded in SiO2 were fabricated by spinodal decomposition of sputter-deposited silicon-rich oxide with a stoichiometry close to that of silicon monoxide. After thermal treatment a mean feature size of about 3 nm was found in the phase-separated structure. The structure of the Si-SiO2 nanocomposite was investigated by energy-filtered transmission electron microscopy (EFTEM), EFTEM tomography, and atom probe tomography, which revealed a percolated Si morphology. It was shown that the percolation of the Si network in 3D can also be proven on the basis of 2D EFTEM images by comparison with 3D kinetic Monte Carlo simulations.

Keywords: Silicon rich oxide; spinodal decomposition; silicon sponge; EFTEM; nanocomposite

Permalink: https://www.hzdr.de/publications/Publ-18945
Publ.-Id: 18945


Plasma-based nanotechnology against corrosion of organ pipes

Pelic, B.; Bregolin, F.; Prucnal, S.; Skorupa, W.; Yankov, R.

Aggressive environments contribute to the corrosion of pipe organs, which causes flaking, losing the voice and final collapse of the old century’s pipes. Additional factor is dezincification of brass (CuZn) containing more than 15 at.% of Zn in the presence of oxygen and moisture. In this approach, the nanotechnology treatment of the CuZn24 (reed organ pipes) is proposed. The conservation strategy based on two stages Pulsed Laser Deposition (PLD) followed by Plasma Immersion Ion Implantation (PIII) were performed. The brass coupons were coated with the protective oxide-films (Al2O3, SiO2, and ZnO) using PLD technique, and implanted with nitrogen ions of energy 20 keV for 200 seconds. The influence of the deposited and implanted coatings, on the corrosion phenomena, has been evaluated by exposing the coupons to the laboratory air with the high concentration of 2% acetic acid (CH3COOH), as aggressive agent. The areal density of the deposited films was measured using Rutherford Backscattering Spectroscopy (RBS). The composition and depth profiling of the sample’s elements was analyzed with Auger Electron Spectroscopy (AES). The average roughness (Ra) of the as coated and implanted specimens was measured using Dektak Stylus Profilometry in 2 and 3 dimensions. Those results were compared with the roughness measurements performed after the corrosion test. A significant improvement in the corrosion resistance with acetic acid action has been achieved by applying aluminum oxide film (30 nm) and introducing nitrogen ions into the near surface and the interphase regions. This gives a light to introduce the nanotechnology into the greatest and best sounding objects of the cultural heritage.

Keywords: Plasma Immersion Ion Implantation; Pulsed Laser Deposition; corrosion of organ pipes

  • Lecture (Conference)
    The 12th International Workshop on Plasma-Based Ion Implantation and Deposition (PBII&D), 01.-05.07.2013, Poitiers, France

Permalink: https://www.hzdr.de/publications/Publ-18944
Publ.-Id: 18944


Protection of organ pipes using plasma-based nanotechnology

Pelic, B.; Bregolin, F.; Prucnal, S.; Wiesenhütter, K.; Yankov, R.; Skorupa, W.

The present historical organs are musical instruments, which provide sound impression of divine music spanning six centuries. Unfortunately, organ pipes, traditionally made of PbSn alloys, have been severely affected by corrosion in the last couple of centuries, and particularly over the last decades. A major threat to the historical organs is harmful indoor environments. Thus, it is necessary to develop a method of protecting the organ pipes, so that the significant cultural heritage obtained over many centuries does not get lost. A new conservation concept based on nanotechnology using plasma immersion ion implantation (PIII) is proposed here for the protection of PbSn alloys exposed to high levels of acetic acid vapors. Samples of organ-pipe quality PbSn alloys with compositions were processed by PIII of either nitrogen or SF6 for different times and bias voltages. The PIII-treated specimens were subsequently studied by Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy to study the concentration/depth profiles of the implanted elements. The implant profiles were also simulated with the aid of the SRIM code. Samples were finally examined using an accelerated corrosion tests in an acetic acid ambient. Both the alloy composition and the implant dose were found to strongly influence the corrosion behavior of the PbSn alloys. The best corrosion resistance was obtained for samples consisting of Pb-Sn15-Sb10 and Pb-Sn28, after the implantation of nitrogen to a dose of1E16cm-2.It was revealed that plasma immersion ion implantation can play an important role in the corrosion prevention of the organ pipes in the acetic acid atmosphere. A protection mechanism was accordingly proposed and discussed.

Keywords: Plasma Immersion Ion Implantation; corrosion of organ pipes; PbSn alloy

  • Lecture (Conference)
    E-MRS 2013 SPRING MEETING, 27.-31.05.2013, Strasbourg, France

Permalink: https://www.hzdr.de/publications/Publ-18943
Publ.-Id: 18943


Einfluss der Bestrahlung mit energiereichen Teilchen auf die Härte von Fe-Cr-Legierungen

Heintze, C.

Ferritisch/martensitische Cr-Stähle und deren oxiddispersionsverfestigte Varianten gehören zu den potenziellen Konstruktionswerkstoffen für Komponenten zukünftiger kerntechnischer Einrichtungen, wie z. B. Fusionsreaktoren und Spalt-reaktoren der IV. Generation, die Strahlungsfeldern mit hohem Neutronenfluss aus-gesetzt sind. Ein Hauptproblem dieser Materialgruppen ist das Auftreten des Spröd-duktil-Übergangs und dessen maßgeblich durch die Strahlenhärtung verursachte Verschiebung zu höheren Temperaturen.
In der vorliegenden Arbeit wird das Bestrahlungsverhalten von binären Fe-Cr-Modelllegierungen untersucht, die ein vereinfachtes Modell für ferritisch/martensitische Cr-Stähle darstellen. Dabei werden Bestrahlungen mit Eisenionen zur Simulation der durch Neutronen hervorgerufenen Schädigung verwendet. Die auf wenige Mikrometer begrenzte Eindringtiefe der Ionen macht es erforderlich, dass für dünne Schichten geeignete Charakterisierungsmethoden ein-gesetzt werden. Im Rahmen dieser Arbeit sind das Nano¬härte¬messungen und Transmissions¬elektronen¬mikroskopie (TEM).
Im Ergebnis liegen die bestrahlungsinduzierte Härteänderung der Schicht in Ab-hängig¬keit von Chromgehalt, Bestrahlungsfluenz und –temperatur sowie, für aus-gewählte Zustände, quantitative TEM-Analysen vor. Zusammen mit begleitenden Ergebnissen von Neutronenkleinwinkelstreuexperimenten an neutronen-bestrahlten Proben der gleichen Werkstoffe ermöglichen sie die Identifizierung von bestrahlungsinduzierten Versetzungsringen und nm-großen α’-Ausscheidungen als Quellen der Strahlenhärtung. Im Rahmen eines vereinfachten Modells, das auf Orowan zurückgeht, werden die Hindernis¬stärken dieser Gitterbaufehler für das Gleiten von Versetzungen abgeschätzt.
Darauf aufbauend erfolgt ausblickartig eine Erweiterung des Untersuchungsgegenstands auf komplexere Situationen hinsichtlich der Bestrahlungs-bedingungen und des Werkstoffs. Durch das Einbeziehen simultaner und sequentieller Bestrahlungen mit Eisen- und Heliumionen kann gezeigt werden, dass der Effekt von Helium auf die Strahlenhärtung von der Bestrahlungs-reihenfolge abhängt und dass der simultane Eintrag fusionsrelevanter Mengen von Helium zu einer Verstärkung der Strahlenhärtung führt, die auf einem synergistischen Effekt beruht. Für Cr-Stähle mit 9 % Cr und deren oxiddispersions-verfestigte Varianten wird kein grundlegend anderes Bestrahlungsverhalten beobachtet als für binäres Fe-9at%Cr. Es gibt jedoch Hinweise, dass Oxid-dispersionsverfestigung die Strahlenhärtung unter bestimmten Bedingungen reduzieren kann.
Im Ergebnis der Arbeit zeigt sich, dass Ionenbestrahlungen in Kombination mit Nanohärtemessungen zu einem vertiefenden Verständnis der Strahlenhärtung in Werkstoffen auf Fe-Cr-Basis sowie zu einer effektiven Materialvorauswahl beitragen können. Voraussetzung ist, dass der Eindruckgrößeneffekt und der Substrateffekt auf geeignete Weise in Rechnung gestellt werden.

Keywords: Fe-Cr-Legierungen; Ionenbestrahlung; Neutronenbestrahlung; Nanohärte; SANS; TEM

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-037 2013
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-18942
Publ.-Id: 18942


Probing the surface speciation of U(VI) on iron (hydr)oxides by in situ ATR FT-IR spectroscopy

Foerstendorf, H.; Jordan, N.; Heim, K.

The surface speciation of uranium(VI) on maghemite (γ-Fe2O3) was elucidated at the spectroscopic level for the first time. By means of in situ ATR FT-IR measurements, the formation of uranium(VI) outer-sphere complexes was revealed under anoxic conditions and in ambient atmosphere at mildly acid conditions. This type of complexation was verified by the frequency of the ν3(UO2) mode observed for the surface species, the impact of the ionic strength of the background electrolyte on U(VI) sorption and by the high reversibility of the sorption process monitored by on line spectroscopy. The impact of carbonate ions from atmospherically derived CO2 on U(VI) sorption on maghemite was investigated. Although the surface speciation of the carbonate ions presumably change from a monodentate coordination on maghemite to a bidentate coordination in the ternary sorption system, the U(VI) speciation is not changed. A contrasting juxtaposition of comparable results obtained from maghemite and ferrihydrite reveal a basically different type of U(VI) complexation, namely outer and inner spheric coordination.

Permalink: https://www.hzdr.de/publications/Publ-18941
Publ.-Id: 18941


Migration-induced field-stabilized polar phase in strontium titanate single crystals at room temperature

Hanzig, J.; Zschornak, M.; Hanzig, F.; Mehner, E.; Stöcker, H.; Abendroth, B.; Röder, C.; Talkenberger, A.; Schreiber, G.; Rafaja, D.; Gemming, S.; Meyer, D. C.

Local reversible structural changes in SrTiO3 single crystals in an external electric field are induced by oxygen redistribution. We present in-situ X-ray diffraction measurements during and immediately after electroformation. Several reflections are monitored and show an elongation of the cubic unit cell of strontium titanate. Raman investigations verify that the expansion of the unit cell involves a transition from the centro-symmetric to a lower symmetry phase. During a complete formation cycle, including the hold time of the electric field and relaxation time without field, two different dynamics are observed for the reversible transitions from cubic symmetry to tetragonal distortion: a slow one during the increase of the lattice constant in field direction and a fast one after switching off the electric field. Based on the experimental data we propose the formation of a polar strontium titanate unit cell at room temperature stabilized by the electric field, which is referred to as migration-induced field-stabilized polar (MFP) phase.

Keywords: ferroic; density-functional; DFT; strontium titanate; STO; migration; RAMAN; oxide

Permalink: https://www.hzdr.de/publications/Publ-18940
Publ.-Id: 18940


Microbial influence on the migration behaviour of radionuclides

Krawczyk-Bärsch, E.

In an underground rock characterization facility, the ONKALO tunnel in Finland, massive 5–10-mm thick biofilms were observed attached to tunnel walls where groundwater was seeping from bedrock fractures at a depth of 70 m. In laboratory experiments performed in a flow cell with detached biofilms to study the effect of uranium on the biofilm, uranium was added to the circulating groundwater obtained from the fracture feeding the biofilm. The final uranium concentration was adjusted to 4.25×10–5 M. EF-TEM studies indicated that uranium in the biofilm was immobilized intracellularly in microorganisms by the formation of metabolically mediated uranyl phosphate, similar to needle-shaped Autunite (Ca[UO2]2[PO4]2•2-6 H2O) or meta-Autunite (Ca[UO2]2[PO4]2•10-12H2O). At the Äspö HRL (Sweden) Gallionella ferruginea dominated biofilms associated with bacteriogenic iron oxides (BIOS) and groundwater were sampled from an in situ continuous flow cell. In laboratory sorption experiments UO2(ClO4)2 and NpO2(ClO4) were added to the BIOS biofilms in groundwater under aerobic conditions adjusting a final U(VI) concentration of 1.9×10-5 M. U(VI) and 3.27×10-5 M Np(V). The results showed a substantial decrease of uranium and neptunium in the groundwater of approximately 85 % and 95 %, respectively. Thermodynamic calculation of the theoretical predominant field of uranium species was performed using the analytical data of the uranium-contaminated groundwater. Under the given pH and Eh the formation of the aqueous uranium carbonate species Ca2UO2(CO3)3(aq) is predicted due to the high concentration of carbonate in the groundwater. In the BIOS biofilm the ferrous iron-oxidizing and stalk-forming bacterium Gallionella ferruginea is dominating the sorption process. The stalk represents an organic surface upon which Fe oxyhydroxides can precipitate. Under the given pH conditions the uptake of U and Np depends predominantly on the high amount of ferrihydrite precipitated onto the stalks. Conclusively, the combination of this biological material and iron oxides creates an abundant surface area for adsorption of radionuclides.

Keywords: biofilm; U(VI); Np(V); Äspö; ONKALO; sorption

  • Lecture (Conference)
    Coordination Meeting at Äspö, 26.04.2013, Äspö, Sweden

Permalink: https://www.hzdr.de/publications/Publ-18939
Publ.-Id: 18939


Microbial experiments at URL sites: Influence on radionuclide

Krawczyk-Bärsch, E.

At the Äspö HRL (Sweden) Gallionella ferruginea dominated biofilms associated with bacteriogenic iron oxides (BIOS) and groundwater were sampled from an in situ continuous flow cell, which has been installed in a cavity of the main access tunnel at 2200 A site, 300 m below sea level In laboratory sorption experiments UO2(ClO4)2 and NpO2(ClO4) were added to the BIOS biofilms in groundwater under aerobic conditions adjusting a final U(VI) concentration of 1.9×10-5 M. U(VI) and 3.27×10-5 M Np(V). The analysis showed a substantial decrease of uranium and neptunium in the groundwater of approximately 85 % and 95 %, respectively. Under the given pH and Eh the formation of the aqueous uranium carbonate species Ca2UO2(CO3)3(aq) is predicted due to the high concentration of carbonate in the groundwater. In the BIOS biofilm the ferrous iron-oxidizing and stalk-forming bacterium Gallionella ferruginea is dominating the sorption process.

Keywords: biofilm; Äspö; U(VI); Np(V); sorption

  • Lecture (Conference)
    Final Workshop of the Crock Project "Crystalline rock retention processes", 14.-16.05.2013, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-18938
Publ.-Id: 18938


Reverse Epitaxy of Ge: Ordered and Faceted Surface Patterns

Ou, X.; Keller, A.; Helm, M.; Fassbender, J.; Facsko, S.

Normal incidence ion irradiation at elevated temperatures, when amorphization is prevented, induces novel nanoscale patterns of crystalline structures on elemental semiconductors by a reverse epitaxial growth mechanism: on Ge surfaces irradiation at temperatures above the recrystallization temperature of 250°C leads to self-organized patterns of inverse pyramids. Checkerboard patterns with fourfold 2 symmetry evolve on the Ge (100) surface, whereas on the Ge (111) surface, isotropic patterns with a sixfold symmetry emerge. After high-fluence irradiations, these patterns exhibit well-developed facets. A deterministic nonlinear continuum equation accounting for the effective surface currents due to an Ehrlich-Schwoebel barrier for diffusing vacancies reproduces remarkably well our experimental observations.

Keywords: ion irradiation; pattern formation; negative epitaxy

Permalink: https://www.hzdr.de/publications/Publ-18937
Publ.-Id: 18937


Formation and coarsening of sponge-like Si-SiO2 nanocomposites

Liedke, B.; Heinig, K.-H.; Mücklich, A.; Schmidt, B.

It has been recently found by energy filtered transmission electron microscopy (EFTEM) that metastable SiOx≈1 films decay into a Si nanowire network embedded in SiO2 by spinodal decomposition during thermal treatment. To have a guideline for nanocomposites fabrication, the details of the morphology evolution have been studied by comparison of EFTEM images with kinetic Monte-Carlo (kMC) simulations. Pair correlation functions calculated by kMC have been adjusted to that extracted from EFTEM. This comparison allows to conclude about characteristic lengths of 3D morphologies. Combining kMC with EFTEM delivers the understanding for tailoring the properties like quantum confinement of the spongy Si

Keywords: sponge-like silicon; nanostructure; annealing; kinetic Monte-Carlo

Permalink: https://www.hzdr.de/publications/Publ-18936
Publ.-Id: 18936


A spectroscopic study on U(VI) biomineralization in cultivated Pseudomonas fluorescens biofilms isolated from granitic aquifers

Krawczyk-Bärsch, E.; Lütke, L.; Moll, H.; Bok, F.; Steudtner, R.; Rossberg, A.

The interaction between the Pseudomonas fluorescens biofilm and U(VI) were studied using extended X-ray absorption fine structure spectroscopy (EXAFS), and time-resolved laser fluorescence spectroscopy (TRLFS). In EXAFS studies, the formation of a stable uranyl phosphate mineral, similar to autunite (Ca[UO2]2[PO4]2•2–6H2O) or meta-autunite (Ca[UO2]2[PO4]2•10–12H2O) was observed. This is the first time such a biomineralization process has been observed in P. fluorescens. Biomineralization occurs due to phosphate release from the cellular polyphosphate, likely as a cell’s response to the added uranium. It differs significantly from the biosorption process occurring in the planktonic cells of the same strain. TRLFS studies of the uranium-contaminated nutrient medium identified aqueous Ca2UO2(CO3)3 and UO2(CO3)3 4− species, which in contrast to the biomineralization in the P. fluorescens biofilm, may contribute to the transport and migration of U(VI). The obtained results reveal that biofilms of P. fluorescens may play an important role in predicting the transport behavior of uranium in the environment. They will also contribute to the improvement of remediation methods in uranium-contaminated sites.

Keywords: EXAFS; Meta-autunite; Pseudomonas fluorescens; TRLFS; Uranium

Permalink: https://www.hzdr.de/publications/Publ-18935
Publ.-Id: 18935


Polyatomic bismuth impacts into germanium: Molecular dynamics study

Anders, C.; Heinig, K.-H.; Urbassek, H.

Using molecular dynamics simulations, we study the effects induced by the impact of Bin (n≤5) clusters with energies in the range of a 3–20 keV/atom into a Ge target. The target consists of Ge including a 10% contribution of randomly distributed Bi atoms. The impacting polyatomic clusters create a long-lived melt pool at the surface. After resolidification, the surface shows a characteristic meniscuslike depression; it is caused both by the missing sputtered atoms and by the volume change of Ge upon melting and amorphization. During cooling, Bi is driven towards the center of the melt pool. A large precipitate forms at the surface (for polyatomic impact) or in the center of the molten pocket (for monatomic impact). The remainder of the resolidified amorphous zone is purified from Bi. We argue that the reason for the demixing of Bi and Ge is the thermophoretic or Soret effect which is caused by the different diffusivities of Bi and Ge in the melt. Bi is sputtered preferentially from the sample. The extent of surface modification, the amount of Bi collected on the surface, the concentration of Bi, and structure of Bi precipitates in the former melt pool are analyzed in their dependence on projectile size, impact energy, and direction.

Keywords: atomistic computer simulation; germanium; polyatomic ions; melting

Permalink: https://www.hzdr.de/publications/Publ-18934
Publ.-Id: 18934


Advanced Numerical and Experimental Studies to Turbulent Buoyancy Driven Flow in the Primary Circuit of Pressurized Water Reactors

Höhne, T.

Validated and accurate advanced simulation tools, in particular advanced Computational Fluid Dynamics (CFD) simulation methods, are required to further improve the economics and safe operation of future nuclear power plants.
These methods will be beneficiary for Generation III+ and Generation IV reactors.
Buoyancy driven flows are of relevance for boron dilution transients or pressurized thermal shock scenarios.
Therefore, a combined numerical and experimental study of buoyant mixing processes is planned in the project using existing experiments of the HZDR test facility ROCOM.
A systematic determination of the advantages, disadvantages, and accuracy of these advanced CFD simulation methods for application to NRS assessments is planned.
This will contribute to the development of Generation III+ and IV nuclear reactors, and thereby to the utilization of more efficient and more economical nuclear power in the future.

Keywords: HZDR; ROCOM; NRS; CFD

  • Invited lecture (Conferences)
    IAEA Workshop, 17.-19.07.2013, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-18933
Publ.-Id: 18933


Linear excitation of short propagating spin waves via a pair of layered vortex cores

Wintz, S.; Weigand, M.; Tyberkevych, V. S.; Slobodianiuk, D. V.; Stoll, H.; Raabe, J.; Neudert, A.; Erbe, A.; Lindner, J.; Slavin, A. N.; Fassbender, J.

The investigation of spin wave dynamics in nanomagnetic systems is one of the key topics in modern magnetism. To excite short spin waves, it is typically necessary either to use transducers of the size of a wavelength (micro-striplines or point-contacts) or to excite the spin waves parametrically by a double-frequency spatially uniform microwave signal. Here we demonstrate that the efficient linear excitation of short propagating spin waves is possible in a trilayer in which the magnetic layers form a vortex pair with opposite circulations and parallel cores. Such spin waves are directly observed by time-resolved x-ray microscopy upon application of microwave magnetic fields of appx. 1 mT. We find that for excitation frequencies in the GHz regime, the resulting spin wavelength is continuously tunable in a range between 50 nm and 500 nm by this frequency. Here, the radial spin wave propagation direction depends on the total handedness of the two vortex circulations, revealing a clear non-reciprocity of the spin waves observed. Both, analytic theory and micromagnetic simulations show that such a nanomagnetic system supports a gapless spin wave branch with linear dispersion and strong nonreciprocity, and that the propagating spin waves belonging to this branch can be excited by a spatially uniform microwave signal. Other excitation mechanisms, such as spin-transfer torques or thermal gradients, could be utilized to generate spin waves in the system presented.

  • Poster
    Gordon Research Conferences: Spin Dynamics in Magnetic Nanostructures, 18.08.2013, Hong Kong, China

Permalink: https://www.hzdr.de/publications/Publ-18932
Publ.-Id: 18932


Results of Testing of Calculation Procedure for Neutron Fluence and Spectrum on the VVER-440 RPV during Operation with new Fuel Compositions

Borodkin, P. G.; Borodkin, G. I.; Adeev, V. A.; Konheiser, J.

In accordance to PNAE G-7-008-89 [1] on the NPP since starting-up should be accounted neutron fluence of RPV, which determines the RPV life-time in accordance to strength calculations. Detailization of these PNAE G-7-008-89 [1] requirements has been represented in the RB-007-99 [2]. Recently elaborated procedure for accounting and prediction of RPV fast neutron fluence has been regulated by normative document RD EO 1.1.2.29.0913-2012 [3].
During NPP unit operation some modernizations have been realized, for example, using of new types of fuel assemblies and new kind of fuel. Changes in the reactor core loading, especially on the core periphery, give influence in the fast neutron fluence on the RPV, which should be evaluated by neutron fluence calculations. The reliability of these calculations should be validated by ex-vessel neutron-activation measurements at NPPs with VVER.
Paper deals with the results of calculations and measurement of fast neutron fluence on the RPV for last fuel cycles of Kola NPP power units, with using new type of fuel, and gives some recommendations for improvement of routine fluence calculation procedures.

Keywords: VVER; neutron fluence; RPV

  • Lecture (Conference)
    Safety Assurance of NPP with WWER, 28.-31.05.2013, Podolsk, Russia
  • Contribution to proceedings
    Safety Assurance of NPP with WWER, 28.-31.05.2013, Podolsk, Russia
    Conference proceedings

Permalink: https://www.hzdr.de/publications/Publ-18931
Publ.-Id: 18931


Synchrotron X-ray tomography of a Taylor bubble

Boden, S.; Hampel, U.

A profound understanding of the transfer processes in capillary multiphase flow is of primary importance from the viewpoint of fundamental science as well as for practical design and operation of new chemical reaction devices. The desired flow regime in such small channel geometries is surface tension dominated Taylor bubble flow. Still today the lack of precise morphological data on such Taylor bubble capillary two-phase flows calls for the development of adequate measurement techniques providing the necessary spatial resolution for the investigation of the flow structures moving at moderate speeds. Experiments to reveal the shape of moving Taylor bubbles were performed at the ANKA synchrotron radiation source in Karlsruhe, Germany, in capillaries with a hydraulic diameter of dh = 2 mm. The careful examination of the bubble positions in the dataset enabled the generation of consecutive projection images necessary for application of a computerized tomographic reconstruction algorithm to reveal the cross-sectional shape of the Taylor bubble.

Keywords: Taylor bubble flow; X-ray tomography; synchrotron

  • Lecture (Conference)
    7th World Congress on Industrial Process Tomography, 02.-05.09.2013, Krakow, Poland

Permalink: https://www.hzdr.de/publications/Publ-18930
Publ.-Id: 18930


Thermal-Hydraulic Investigations for Safety Related Tasks

Höhne, T.

The session „Thermal-Hydraulic Investigations for Safety Related Tasks“ was chaired by Thomas Höhne (Helmholtz-Zentrum Dresden - Rossendorf ).
The first presentation on „Comparative analysis of a LOCA for a German PWR with ASTEC and ATHLET-CD“, from Nils Reinke (Co-authors: H.-W. Chan, M. Sonnenkalb, all from the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH, Köln) presented calculations with the German-French severe accident integral code ASTEC for the early phase of the accident, thereby focusing on thermal-hydraulics mainly. He explained that the purpose of this work was mainly to assess the ASTEC code behavior in modeling thermal-hydraulics in the coolant circuit in the early phase of a hypothetical severe accident. This is in particular interesting, since the early phase of the accident determines core heat-up and the subsequent core degradation phase. A comparison is done versus the more mechanistic code system ATHLET-CD/COCOSYS, developed at GRS, too.

Keywords: KTG; Jahrestagung Kerntechnik; Thermal-Hydraulic; CFD

  • atw - International Journal for Nuclear Power 58(2013)10, 587-588

Permalink: https://www.hzdr.de/publications/Publ-18929
Publ.-Id: 18929


Ortsaufgelöste Analyse von Uranspezies mittels einem gekoppelten System aus CLSM und LIFS

Großmann, K.; Arnold, T.; Brockmann, S.

Die fluoreszierenden Eigenschaften des Urans bei Anregung mit UV-Licht werden zunehmend für spektroskopische Analysen von Uranspezies innerhalb wässriger Proben eingesetzt. Dabei spielen neben den Fluoreszenzeigenschaften der sechswertigen Oxidationsstufe auch zunehmend die der vier- und fünfwertigen Oxidationsstufe eine wichtige Rolle. Bei Fluoreszenzmessungen von Uranverbindungen sind die Emissionsbandenlagen sowie die Fluoreszenzlebenszeit (die Abklingzeit der Fluoreszenzlichtemission nach der Anregung) wichtige Parameter. Durch Abgleich der ermittelten Peaklagen und Lebenszeiten mit denen von Referenzverbindungen lassen sich somit Aussagen zur vorhandenen Uranspezies treffen. Die Detektion von Fluoreszenzemissionsspektren an festen bzw. biologischen Proben mittels (zeitaufgelöster) laserinduzierter Fluoreszenzspektroskopie (TRLFS bzw. LIFS) hat jedoch den Nachteil, dass keine Aussagen zur räumlichen Lokalisation des Urans möglich sind. Gerade in komplexen, biologischen Proben, wie Biofilmverbänden oder mikrobiellen Zellen, sind jedoch Aussagen zum Ort der Urananreicherung in der Probe erwünscht um z.B. zwischen intra- und extrazellulären Urananbindungen unterscheiden zu können.
Die Fluoreszenzeigenschaften der Uran(VI)verbindungen und –minerale können auch zu deren Lokalisation innerhalb von komplexen Proben genutzt werden. So stellt die Anwendung fluoreszenzmikroskopischer Messmethoden eine Möglichkeit dar, Uranpräzipitate und Anreicherungen z.B. in biologischen Proben wie Biofilmen oder Zellen zu lokalisieren und zu visualisieren. Die konfokale Laser-scanning Mikroskopie (CLSM) eignet sich hierbei besonders, da diese Methode eine dreidimensionale Darstellung fluoreszierender Bereiche in komplexen Probenstrukturen ermöglicht. Durch Anwendung geeigneter Fluoreszenzfarbstoffe kann auch die sonstige Probenstruktur abseits der fluoreszierenden Schwermetalle abgebildet werden, wodurch eine räumliche Einordnung innerhalb der Probengeometrie ermöglicht wird [1].
Eine Kopplung der konfokalen Laser-scanning Mikroskopie (CLSM) mit der laserinduzierten Fluoreszenzspektroskopie (LIFS) ermöglicht es Fluoreszenzsignale räumlich, dreidimensional zu lokalisieren und zu visualisieren sowie gleichzeitig entsprechende ortsaufgelöste, fluoreszenz-spektroskopische Daten zu detektieren [2]. Verschiedene erfolgreiche Anwendungen an biologischen Proben aber auch an Mineraloberflächen zeigen, dass es sich bei dieser kombinierten Methode aus Mikroskopie und Spektroskopie um eine zukunftsweisende Technik zur zerstörungsfreien Detektion von fluoreszierenden Schwermetallen und besonders der Uran(VI)spezies handelt. Diese Methode ist besonders vielversprechend hinsichtlich der Detektion von Uran(VI)akkumulationen innerhalb von komplexen Probensystemen deren Struktur und Aufbau durch die Analyse der Uranspezies nicht zerstört werden soll. Dabei zeichnet sich diese Technik durch relativ niedrige Nachweisgrenzen von bis zu 1∙10-6 M für Uran(VI)verbindungen innerhalb des konfokalen Volumens aus.

  • Poster
    7. Workshop RCA, 10.-11.06.2013, Rossendorf, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-18928
Publ.-Id: 18928


Growth of a three-dimensional anisotropic lattice of Ge quantum dots in an amorphous alumina matrix

Buljan, M.; Roshchupkina, O.; Santic, A.; Holy, V.; Baehtz, C.; Mücklich, A.; Horak, L.; Vales, V.; Radic, N.; Bernstorff, S.; Grenzer, J.

Simple processes for the preparation of semiconductor quantum dot lattices embedded in dielectric amorphous matrices play an important role in various nanotechnology applications. Of particular interest are quantum dot lattices with properties that differ significantly in different directions parallel to the material surface. Here, a simple method is demonstrated for the fabrication of an anisotropic lattice of Ge quantum dots in an amorphous Al2O3 matrix by a self-assembly process. A specific deposition geometry with an oblique incidence of the Ge and Al2O3 adparticles was used during magnetron sputtering deposition to achieve the desired anisotropy. The observed Ge quantum dot ordering is explained by a combination of directional diffusion of adparticles from the Ge and Al(2)O(3)targets and a shadowing process which occurs during deposition as a result of the specific surface morphology. The prepared material shows a strong anisotropy of the electrical conductivity in different directions parallel to the sample surface.

Keywords: Ge quantum dots; self-assembly; conductivity; anisotropy; magnetron sputtering; synthesis

Permalink: https://www.hzdr.de/publications/Publ-18927
Publ.-Id: 18927


The neutron-proton charge-exchange amplitudes measured in the dp -> ppn reaction

Mchedlishvili, D.; Barsov, S.; Carbonell, J.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Engels, R.; Gebel, R.; Glagolev, V.; Grigoryev, K.; Goslawski, P.; Hartmann, M.; Kacharava, A.; Kamerdzhiev, V.; Keshelashvili, I.; Khoukaz, A.; Komarov, V.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Maier, R.; Merzliakov, S.; Mielke, M.; Mikirtychyants, M.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H.; Steffens, E.; Stockhorst, H.; Stroher, H.; Tabidze, M.; Trusov, S.; Uzikov, Y.; Valdau, Y.; Wilkin, C.

The unpolarised differential cross section and the two deuteron tensor analysing powers A(xx) and A(yy) of the (d) over right arrowp -> {pp}(s)n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27 GeV, data were obtained for small momentum transfers to a {pp}(s) system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27 GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C-x,C-x and C-y,C-y that were carried out in the (d) over right arrow(p) over right arrow -> {pp}(s)n reaction at 1.2 and 2.27 GeV. The values obtained for the proton analysing power A(y)(p) also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region.

Permalink: https://www.hzdr.de/publications/Publ-18926
Publ.-Id: 18926


The ternary system U(VI) / humic acid / Opalinus Clay

Joseph, C.

The storage of nuclear waste in deep geological formations is discussed worldwide as the main strategy for nuclear waste management. To ensure the confinement of the nuclear waste, a multiple barrier system which consists of engineered, geo-engineered, and geological barriers will be applied. Thereby, in Germany the definition of the isolating rock zone represents an important safety function indicator.
Clay rock is internationally investigated as potential host rock for a repository and represents a part of the geological barrier. In the present work, the natural clay rock Opalinus Clay from the Mont Terri rock laboratory, Switzerland, was studied.
In Germany, the direct disposal of the spent nuclear fuel without the reprocessing of the spent fuel is preferred. In case of water ingress, radionuclides can be released from the nuclear waste repository into its surroundings, namely the host rock of the repository. Humic acids, ubiquitous in nature, can be found associated with the inorganic components in natural clay rock (1.5×10–3 wt.% in Opalinus Clay). They can be released under certain conditions. Due to their variety of functional groups, humic acids are very strong complexing agents for metal ions. They have inherent redox abilities and a colloidal conformation in solution. Because of these characteristics, humic acids can affect the mobility of metal ions such as actinides. Furthermore, in the near-field of a repository elevated temperatures have to be considered due to the heat production resulting from the radioactive decay of the various radionuclides in the nuclear waste.
This work focuses on the interaction of uranium, as main component of spent nuclear fuel, with Opalinus Clay and studies the influence of humic acid and elevated temperature on this interaction. For investigation of the retention behavior of the clay and the mobility of U(VI) in the system, batch sorption and diffusion experiments were performed. To clarify which U(VI) and humic acid species were present under the applied conditions, aqueous speciation modeling was used. Additionally, the U(VI) speciation in solution and on the clay surface was investigated by spectroscopic methods.

Prior to the investigation of the ternary system U(VI) / humic acid / clay, the applied batches of Opalinus Clay were characterized (e.g., specific surface area, carbon content, cation exchange capacity, elemental composition, particle size distribution). Leaching studies with Opalinus Clay in synthetic Opalinus Clay pore water (pH 7.6, It = 0.34 mol/L) and in NaClO4 (pH 3 – 10, I = 0.1 mol/L) were performed to identify the competing ions and their concentrations in the background electrolytes. These data were used to calculate the U(VI) and humic acid speciation in solution. Calcium and carbonate ions are present under pore water conditions as well as in 0.1 mol/L NaClO4 from pH 7 to 8.5, due to dissolution of calcite (mineral fraction in Opalinus Clay). Thus, the U(VI) speciation is dominated by the aquatic Ca2UO2(CO3)3 complex. In the case of pore water, Ca2UO2(CO3)3(aq) is also the dominant U(VI) species in the presence of humic acid, which was corroborated by time-resolved laser-induced fluorescence spectroscopic measurements. A significantly changed speciation was found in 0.1 mol/L NaClO4 in the presence of humic acid. At pH > 7, the negatively charged UO2(CO3)2HA(II)4– complex determines the U(VI) speciation, thus repressing the Ca2UO2(CO3)3(aq) complex. In addition, the speciation of humic acid is influenced from ions leached out from Opalinus Clay. The CaHA(II) complex is the dominating humic acid species in solution.
Batch sorption experiments in 0.1 mol/L NaClO4 showed that Opalinus Clay has the strongest retardation effect on U(VI) in the pH range from pH 4.5 to 7. However, under environmentally relevant conditions (pH > 7), the sorption of U(VI) onto Opalinus Clay is very weak. Under pore water conditions, a distribution coefficient (Kd) of 0.0222 ± 0.0004 m3/kg was determined, which was shown to be independent of solid-to-liquid ratios ≥ 60 g/L. In addition, in pore water, the U(VI) sorption onto Opalinus Clay is not influenced by humic acid, which is supported by the speciation results. Extended X ray absorption fine-structure investigations confirmed this batch sorption result.
The U(VI) diffusion experiments performed in pore water at 25 °C with Opalinus Clay bore core samples confirmed the Kd value obtained by batch sorption experiments. In the diffusion experiments at 60 °C, a change in the U(VI) speciation occurred. Beside Ca2UO2(CO3)3(aq), a colloidal U(VI) species was formed. Almost equivalent apparent diffusion coefficient (Da) values were determined for the diffusion of the aqueous U(VI) species at 25 and 60 °C through Opalinus Clay. Thus, based on the investigations in the present study the breakthrough of U(VI) through Opalinus Clay is expected to be independent of the temperature and should occur nearly at the same time. Modeling calculations showed that it would take about 10 years until a detectable amount of 233U(VI) (1×10–9 mol/L) migrates through an 11 mm thick Opalinus Clay sample.
Two distinct humic acid size fractions – a large- and a small-sized colloid fraction – diffused through the Opalinus Clay samples. Within three months, the high molecular size humic acid colloids migrated only about 500 µm into the clay, whereas the low molecular size fraction diffused through the entire Opalinus Clay samples and were consequently detected in the receiving reservoirs. These findings demonstrate a filtration effect of the compacted clay. The diffusion experiments revealed that the effect of humic acid on U(VI) diffusion is negligible and, under the studied conditions, independent of temperature.
The obtained results contribute to data bases used for modeling of interaction and migration processes in uranium / clay rock systems. Thus, the collected sorption and diffusion data are not only relevant for safety assessment of nuclear waste repositories but also for any clay-containing system present in the environment, where the geochemical interaction with uranium contaminated water plays a role.
Concerning the suitability of Opalinus Clay as host rock for a nuclear waste repository, it can be concluded, that Opalinus Clay has a relatively high retardation potential for U(VI). In case of water ingress U(VI) as part of the nuclear waste is released into the clay formation. Under near-neutral pH conditions, it will be complexed by calcium and carbonate ions leached out from Opalinus Clay, whereby Ca2UO2(CO3)3(aq) is formed. This complex is only weakly retarded by sorption onto the clay, which can contribute to an enhanced mobility of U(VI) in the host rock. However, the U(VI) migration through the clay rock is governed by molecular diffusion. This decelerates the migration of Ca2UO2(CO3)3(aq) through Opalinus Clay and thus it represents the decisive retardation process in the investigated system. Additionally, under environmentally relevant conditions, humic acid has no significant influence on U(VI) / Opalinus Clay interaction even at an elevated temperature of 60 °C. This was shown by speciation, sorption, as well as diffusion experiments.

Keywords: uranium(VI); humic acid; Opalinus Clay; sorption; diffusion; speciation

  • Doctoral thesis
    TU Dresden, 2013
    163 Seiten

Permalink: https://www.hzdr.de/publications/Publ-18925
Publ.-Id: 18925


Embrittlement of TiAl after high temperature exposure

Paul, J.; Bleicher, F.; Bortolotto, L.; Geiger, G.; Kolitsch, A.; Langlade, C.; Masset, P.; Pelic, B.; Pyczak, F.; Rafaja, D.; Schimansky, F.-P.; Schumacher, P.; Schütze, M.; Wolf, G.; Yankov, R.

It is well known that the room temperature ductility of gamma-based titanium aluminide alloys is significantly reduced after exposure to elevated temperatures. In some cases exposure can even lead to brittle fracture on reloading of an initially ductile alloy. However the original ductility can be restored if around 30 to 50 µm of the exposed surface is removed before testing. In an attempt to reduce this problem, the effect of coatings combined with halogen treatment on the tensile behaviour of cast + HIPed Ti-48Al-2Cr-2Nb has been investigated. This talk will give a general outline of the embrittlement problem and present current ideas that have been postulated to explain the embrittlement mechanism. Additionally the protective coating methods used in the study will be presented; mechanical test results of specimens that had undergone protective coating treatments are compared to those obtained for un-treated specimens after being oxidised at 900°C for 100 hours.

Keywords: titanium aluminides; oxidation protection; coating

  • Lecture (others)
    International Workshop on Gamma Alloy Technology (GAT 2013), 11.-14.06.2013, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-18924
Publ.-Id: 18924


Shielding and activation calculations for the FASTEF-MYRRHA ADS design in the subcritical operation mode

Ferrari, A.; Di Maria, S.; Sarotto, M.; Stankovskiy, A.

Accelerator-driven systems (ADS) are one of the options studied for transmutation of nuclear waste in the European Community. The present study has been done in the frame of the FP7 European project Central Design Team (CDT), which in the years 2009-2012 worked to design the FAst Spectrum Transmutation Experimental Facility (FASTEF) with the goal to demonstrate efficient transmutation of high level waste and associated ADS technology. On this design will be based the MYRRHA reactor at SCK•CEN in Mol (Belgium), which should enter the construction phase in 2015. The heart of the system is a lead-bismuth eutectic (LBE) cooled reactor, working both in critical and in sub-critical operation modes. The neutrons needed to sustain fission in the subcritical mode are produced via spallation processes by a 600 MeV, 4 mA proton beam, which is provided by a linear accelerator and hits a LBE spallation target located inside the reactor core. The use of high energy/high current proton beams, in combination with a nuclear reactor core operating in subcritical or critical mode, presents many challenges for various aspects of the design, being radiation shielding and minimization of the induced activation key points.

Keywords: Accelerator Driven Systems; Reactor safety; Monte Carlo; Shielding

  • Contribution to proceedings
    2013 ANS Winter Meeting, Session "Best of ICRS/RSPD 2012" (invited), 10.-14.11.2013, Washington, DC, USA
    Transactions of the American Nuclear Society, Volume 109, La Grange Park, Illinois: American Nuclear Society, ISSN:0003-018X, 1249-1251

Permalink: https://www.hzdr.de/publications/Publ-18923
Publ.-Id: 18923


Surface complexation and oxidation of SnII by nano-magnetite

Dulnee, S.; Banerjee, D.; Merkel, B.; Scheinost, A. C.

The long-lived fission product 126Sn is of substantial interest in the context of nuclear waste disposal in deep underground repositories. However, the prevalent redox state (di- or tetravalent), the aqueous speciation as well as the reactions at the mineral-water interface under the expected anoxic conditions are still a matter of debate. We therefore investigated the reaction of SnII with a relevant redox-reactive mineral, magnetite (FeIIFeIII2O4) at < 2 ppmv O2, and monitored Sn uptake as a function of pH and time. Tin redox state and local structure was monitored by Sn-K X-ray absorption spectroscopy (XAS). We observed a rapid (< 30 min) uptake and oxidation of SnII to SnIV in the presence of magnetite. The local structure determined by XAS showed two Sn-Fe distances of about 3.15 and 3.60 Å in line with edge and corner sharing arrangements between octahedrally coordinated SnIV and the magnetite surface, indicative of formation of tetradentate inner-sphere complexes between pH 3 and 9, in line with the strong sorption (logRd >5 from pH 3 to 9). Based on the EXAFS-derived surface structure, we could successfully model the sorption data with two different complexes, (Magn_sO)4Sn(OH)2-2 ( -14.97±0.35) prevailing from pH 2 to 9, and (Magn_sO)4Sn(OH)2Fe ( -17.72±0.50), which forms at pH > 9 by co-adsorption of FeII, thereby increasing sorption at this high pH.

Keywords: Sn; Redox; Surface complexation; Nuclear waste; magnetite; EXAFS; XANES; XRD; TEM

Permalink: https://www.hzdr.de/publications/Publ-18922
Publ.-Id: 18922


Mineralogical characterization of REE mineralization in Norra Kärr alkaline complex, Sweden

Atanasova, P.; Krause, J.; Gutzmer, J.

Alkaline complexes comprise one of the most promising future sources for rare earth element supply. They are particularly enriched in heavy rare earth elements. However, the often complex and highly unusual mineralogy of REE-enriched ores from alkaline complexes pose particular challenges for beneficiation. A geometallurgical approach is required to quantify mineralogical and textural diversity and variability. Based on a geometallurgical model, a suitable approach to beneficiation can be developed. Scanning electron microscope (SEM)-based image analysis can be used to characterize ores as well as beneficiation products. A wide range of tangible mineralogical and textural parameters are constrained for every ore type, including mineral abundance, grain size, and liberation. SEM-based image analysis combined with a quantitative analysis of the chemical composition of the ore minerals is illustrated here for the case of the Norra Kärr alkaline complex, Sweden. Current research focuses on quantitative mineralogical and textural constraints for different lithological domains recognized in the HREE-Zrmineralized zones of the complex. Based on the results, a geometallurgical model will be developed that will be based on the processing characteristics of the different portions of the mineralized zones.

Keywords: rare earth elements; alkaline complex; geometallurgy; eudialyte; nepheline-syenite

  • Contribution to proceedings
    Mineral Deposit Research for a High-tech World: 12th SGA Biannial Meeting, 12.-15.08.2013, Uppsala, Sweden
    Mineral Deposit Research for a High-tech World: 12th SGA Biannial Meeting, 978-91-7403-207-9, 298-301
  • Lecture (Conference)
    Mineral Deposit Research for a High-tech World: 12th SGA Biannial Meeting, 12.-15.08.2013, Uppsala, Sweden
  • Lecture (others)
    FEI User Group Meeting, 08.-09.10.2013, Eindhoven, Holland

Permalink: https://www.hzdr.de/publications/Publ-18921
Publ.-Id: 18921


Block Kriging for geometallurgical optimization

Tolosana-Delgado, R.; Mueller, U.; van den Boogaart, K. G.; Ward, C.

Adpative processing is often related to the mineral composition of the mining block currently processed. The portions of waste, ore and secondary product minerals considered are always positive and typically sum to 100%, i.e. a composition. A typical solution to predict block averages of spatially dependent quantities would be block kriging. However, kriging is based on spatial correlations and it has been repeatedly shown that correlations of compositional data are spurious and blurred by the constant sum constraint.

Aitchison (1982) proposed a general solution for compositional problems, based on transforming the compositional data to a set of logarithms of ratios of components, and analysing the transformed scores. The transform is chosen to be invertible to ensure that no information is lost in the process. This methodology avoids spurious correlation problems and ensures coherence between results obtained with different subcompositions. Pawlowsky-Glahn and Olea (2004) already adapted the approach for point-support geostatistics, allowing the prediction of point compositions from spatially neighbouring data, without the artefacts induced by using standard multivariate cokriging. Unfortunately upscaling the results of this approach with block kriging is not straightforward, because of the nonlinearity of logratio transforms. Furthermore, we have to consider those nonlinearities created by the dependence on the block composition of extraction efficiency and processing costs of the possible processing choices.

This paper proposes a solution for predicting the conditional expectations of the benefit of processing the block with each processing choice using geostatistical simulations of the local values of the composition and the resulting block integrals. The computation for a large number of blocks can be done efficiently using Cholesky decomposition. The approach also allows the calculation of prediction errors for expected compositions and expected benefit at almost no additional computational cost. Such compositional approach is necessary, e.g.: when processing choices depend on proportions of certain minerals after other components have been removed; or if processing alters the composition in a multiplicative way, by partially removing a portion of some components.

Keywords: Compositional data analysis; optimization; negative bias; uniform conditioning

  • Contribution to proceedings
    23rd World Mining Congress, 11.-15.08.2013, Montreal, Canada

Permalink: https://www.hzdr.de/publications/Publ-18920
Publ.-Id: 18920


Regression between compositional data sets

Tolosana-Delgado, R.; van den Boogaart, K. G.

Linear regression where both the explained and the explanatory variables form compositions are naturally tractable within the log-ratio framework. Fitting such models does not imply any diculty: they can be t in a standard way after applying any one-to-one logratio transformation to each compositional set. Problems arise to test and display the model, due to the large dimension of the model parameters space, and the dicult interpretation of classical hypotheses in terms of the original components. This contribution proposes two graphical representations of the model: in the form of a biplot, parallel to redundacy analysis, and as condence ellipses on the parameters projected onto a set of subcompositions. Each of these representations brings also associated a way to test for certain subcompositional independence hypotheses. An exact, general, Scheffé-like test of independence (for the whole composition or any subcomposition) can be derived from a generalized eigenvalue problem of the matrix of regression coecients and its estimation covariance matrix. For certain hypotheses of independence, classical tests based on Hotelling's T2 or X2 distributions can also be adapted. Any of these tests can be used to calculate the radii of condence ellipses on the parameters, in order to visualize the corresponding tests. This provides a toolbox to reduce the complexity of compositional-to-compositional regression, and enables a structured way of exploring and testing which components of the explanatory set influence which components of the explained set.

  • Open Access Logo Contribution to proceedings
    the 5th International Workshop on Compositional Data Analysis, 03.-07.06.2013, Vorau, Österreich
    Proceedings of the 5th International Workshop on Compositional Data Analysis, 978-3-200-03103-6, 164-188

Permalink: https://www.hzdr.de/publications/Publ-18919
Publ.-Id: 18919


Compositional regression with unobserved components or below detection limit values

van den Boogaart, K. G.; Tolosana-Delgado, R.; Hron, K.; Templ, M.; Filzmoser, P.

The typical way to deal with zeroes and missing values in compositional data sets is to impute them with a reasonable value, and then the desired statistical model is estimated with the imputed data set, e.g. a regression model. This contribution aims at presenting alternative approaches to this problem within the framework of Bayesian regression with a compositional response. In a first step, a compositional data set with missing data is considered to follow a normal distribution on the simplex, which mean value is given as an Aitchison ane linear combination of some fully-observed explanatory variables. Both the coecients of this linear combination and the missing values can be estimated with standard Gibbs sampling techniques. In a second step, a normally-distributed additive error is considered superimposed on the compositional response, and values are taken as \below the detection limit" (BDLs) if they are \too small" in comparison with the additive standard deviation of each variable (usually, a 3 rule is applied here). Within this framework, the regression parameters and all missing values (including BDLs) can be estimated, albeit this time with a less ecient Metropolis-Hastings algorithm. Both methods estimate the regression coecients without need of any preliminary imputation step, and adequately propagate the uncertainty derived from the fact that the missing values and BDLs are not actually observed, something imputation methods cannot achieve.

  • Open Access Logo Contribution to proceedings
    CoDaWork'2013: the fifth international Workshop on Compositional Data Analysis, 03.-07.06.2013, Vorau, Österreich
    Proceedings of CoDaWork'2013: the fifth international Workshop on Compositional Data Analysis, 978-3-200-03103-6, 10-19

Permalink: https://www.hzdr.de/publications/Publ-18918
Publ.-Id: 18918


The challenges of adaptive processing to geostatistical prediction

van den Boogaart, K. G.; Konsulke, S.; Tolosana Delgado, R.

Adaptive Processing as proposed in geometallurgy has to rely on spatially interpolated information on geometallurgical parameters like phase composition, size distributions of particles of different phases, grain shape parameters, and portions of value elements in different grains. Using the geostatistically predicted values for adaptive processing, e.g. for the selection of milling diameters, thresholds in physical separation, or choices on using an extra pre-separation step, is typically not optimal. Mathematically this effect is introduced by two forms of nonlinearities: 1) The nonlinear scales of compositions, distributions, and shapes have special properties with respect to geostatistics. Classical geostatistics creates some artefacts for these nonlinear scales. On the other hand, modern geostatistical procedures adapted to these scales do not provide unbiased results with respect to linear transformations of the data (e.g. biased block estimates). 2) Neither economic nor ecological effects (e.g. monetary gain) of processing decisions are linear in the interpolated geometallurgical parameters. These nonlinear transforms are not unbiasedly estimated by the likewise transformed unbiased geostatistical predictions of the geometallurgical parameters. Furthermore, we need to optimize the conditional expectation of the gain, rather than obtain an unbiased estimate. Standard geostatistics as such does not provide the "right sort" of estimates for adaptive processing. A nonlinear kriging procedure is needed to approximate the nonlinearities mentioned before.

We propose to solve these problems simultaneously using a nonlinear geostatistical technique for predicting the target function (the monetary gain), rather than to predict the geometallurgical parameters and compute the gain from them. The optimization can then be performed directly on this estimated function.
It can be shown that this optimization performed on the conditional expectations, not on unbiased predictions, would yield the best possible processing choice. We propose a procedure choosing the processing parameters on an approximation of the conditional expectation. The difficulties with the classical approach and the effectiveness of this new approach are illustrated by a simplified simulation example with a single processing parameter and a simple dependence on the microstructure.

Keywords: geometallurgy; nonlinear geostatistics; optimisation; processing

  • Contribution to proceedings
    23rd World Mining Congress, 11.-15.08.2013, Montreal, Canada
    23rd World Mining Congress 2013 Proceedings, 978-1-926872-15-5

Permalink: https://www.hzdr.de/publications/Publ-18917
Publ.-Id: 18917


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