Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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33407 Publications

Analysis Methods of Magnesium Chips

Ohmann, S.; Ditze, A.; Scharf, C.
The quality of recycled magnesium from chips depends strongly on their exposure to inorg. and org. impurities that are added during the prodn. processes. Different kinds of magnesium chips from these processes were analyzed by several methods. In addn., the accuracy and effectiveness of the methods are discussed. The results show that the chips belong either to the AZ91, AZ31, AM50​/60, or AJ62 alloy. Some kinds of chips show deviations from the above-​mentioned normations. Different impurities result mainly from transition metals and lime. The water and oil content does not exceed 25​%, and the chip size is not more than 4 mm in the diam. The sieve anal. shows good results for oily and wet chips. The detn. of oil and water shows better results for the application of a Soxhlet compared with the addn. of lime and vacuum distn. The most accurate values for the detn. of water and oil are obtained by drying at 110°C (for water) and washing with acetone (for oil) by hand.

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Permalink: https://www.hzdr.de/publications/Publ-22533
Publ.-Id: 22533


Oxyhydroxy silicate colloids: A new type of waterborne actinide(IV) colloids

Zänker, H.; Weiss, S.; Hennig, C.; Brendler, V.; Ikeda-Ohno, A.
At the near-neutral and reducing aquatic conditions expected in undisturbed ore deposits or in closed nuclear waste repositories, the actinides Th, U, Np and Pu are primarily tetravalent. These tetravalent actinides (An(IV)) are sparingly soluble in aquatic systems and, hence, are often assumed to be immobile. However, An(IV) could become mobile if they occur as colloids. This mini-review focuses on a new type of An(IV) colloids, oxyhydroxy silicate colloids. We herein discuss the chemical characteristics of these colloids and the potential implication for their environmental behavior. The binary oxyhydroxy silicate colloids of An(IV) could be potentially more mobile as a waterborne species than the well-known mono-component oxyhydrox-ide colloids.
Keywords: Tetravalent actinides, thorium(IV), uranium(IV), neptunium(IV), silica, colloids, colloid stability, nuclear waste repositories

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Permalink: https://www.hzdr.de/publications/Publ-22532
Publ.-Id: 22532


All-optical free electron lasers with Traveling-wave Thomson-scattering -- Realizable with existing machines

Debus, A.; Steiniger, K.; Pausch, R.; Irman, A.; Jochmann, A.; Schramm, U.; Cowan, T.; Bussmann, M.
Optical free-electron lasers (OFEL) based on the Traveling-wave Thomson scattering (TWTS) geometry [*] are realizable using existing petawatt class laser systems and electron beams from either conventional or Laser-wakefield accelerators. Such OFELs operate in the EUV to x-ray range, while at the same time remaining compact with centimeter to sub-meter total length.

Based on results from our analytical 1.5D-theory, as well as numerical investigations, we show using example scenarios that TWTS OFELs can be realized in SASE mode with existing RF sources such as ELBE at HZDR as well as Laser-wakefield accelerated electrons. We detail the necessary equipment for a TWTS OFEL experiment and discuss how current experimental limitations affect the design.
Keywords: Thomson-scattering, X-ray, FEL, PIConGPU, OFEL, optical free-electron laser, EUV, Traveling-wave, TWTS
  • Poster
    37th International Free Electron Laser Conference - FEL2015, 23.-28.08.2015, Daejeon, Südkorea

Permalink: https://www.hzdr.de/publications/Publ-22531
Publ.-Id: 22531


All-optical free-electron lasers with Traveling-wave Thomson-scattering -- Theory and scaling

Debus, A.; Steiniger, K.; Pausch, R.; Irman, A.; Jochmann, A.; Schramm, U.; Cowan, T.; Bussmann, M.
In Traveling-Wave Thomson-Scattering (TWTS) an optical, high-power laser pulse is scattered off a relativistic electron pulse to realize optical ree-electron lasers (OFELs) with a wavelength ranging from ultraviolet to Angstrom [*].

Such TWTS-OFELs optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation, so that beam electrons witness an undulator field of near-constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.

In contrast to head-on OFEL schemes, TWTS-OFEL operates at sub-mm to mm effective undulator wavelength. Thus previous show-stoppers to OFELs due to small transverse coherence, large space charge or significant quantum effects are avoided. One of the key advantages of this approach is its scalability to x-ray wavelengths with existing lasers. We present the complete analytical description of the TWTS field and a self-consistent 1.5D theory of TWTS OFELs. We discuss the main scalings of resulting
TWTS OFELs with respect to electron and laser beam properties.
Keywords: Traveling-wave, Thomson scattering, X-ray, EUV, OFEL, FEL, optical free-electron laser
  • Poster
    37th International Free Electron Laser Conference - FEL2015, 23.-28.08.2015, Daejeon, Südkorea

Permalink: https://www.hzdr.de/publications/Publ-22530
Publ.-Id: 22530


Realizing All-Optical Free-Electron Lasers with Traveling-Wave Thomson-Scattering

Debus, A.; Steiniger, K.; Pausch, R.; Bussmann, M.; Irman, A.; Jochmann, A.; Röser, F.; Schramm, U.; Sauerbrey, R.
We show how all-optical free-electron lasers (OFELs) from EUV to the X-ray range can be realized using existing high-power lasers and electron accelerators.
Keywords: Traveling-wave, Thomson scattering, OFEL, FEL, optical free-electron laser, X-ray, EUV
  • Poster
    3rd ARD ST3 Workshop, 15.-17.07.2015, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22529
Publ.-Id: 22529


Radiation from laser-plasma interactions - From diagnostics to all-optical free-electron lasers

Debus, A.; Steiniger, K.; Pausch, R.; Bussmann, M.; Irman, A.; Jochmann, A.; Röser, F.; Schramm, U.; Sauerbrey, R.
Radiation spectra from Laser-Plasma interactions are straightforward to obtain in experiment, but due to the large number of simulated particles these are challenging to model ab-initio. Since the emitted spectra include the complete phase-space dynamics, they are a key to both designing and optimizing brilliant plasma-driven x-ray sources for applications such as ultra-short pump-probe experiments. We present angularly-resolved em-radiation spectra from all billions of particles in a laser-plasma simulation, including the full coherence properties from plasma structure and dynamics. These spectra range from far IR to X-rays. We show recent results from the multi-GPU, open-source code PIConGPU.

We use very similar methods, when designing optical free-electron lasers (OFELs) driven by Laser-wakefield accelerated (LWFA) electrons using both existing LWFA beams and OFEL driver lasers. Such optical FELs (OFELs) based on Traveling-wave Thomson scattering (TWTS) optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation. With careful dispersion control, electrons witness an undulator field of almost constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.
Keywords: Traveling-Wave, Thomson scattering, X-ray, FEL , OFEL, optical free-electron laser
  • Lecture (Conference)
    Novel Light Sources from Laser-Plasma Interactions, 20.-24.04.2015, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22528
Publ.-Id: 22528


Optical free-electron lasers on table-top with Traveling-wave Thomson scattering

Debus, A.; Steiniger, K.; Bussmann, M.; Pausch, R.; Cowan, T.; Irman, A.; Jochmann, A.; Sauerbrey, R.; Schramm, U.
Optical FELs (OFELs) based on Traveling-wave Thomson scattering (TWTS) optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation. With careful dispersion control, electrons witness an undulator field of almost constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.
We provide an overview on the differences between TWTS OFELs, head-on OFEL designs and magnetic undulator FELs. In this dicussion we emphasize the respective impact on transverse coherence, quantum recoil and space-charge.
Keywords: Optical free-electron laser, OFEL, Traveling-wave, Thomson scattering, TWTS, FEL, X-ray
  • Lecture (Conference)
    DPG Frühjahrstagung Wuppertal 2015, 09.-13.03.2015, Wuppertal, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22527
Publ.-Id: 22527


Reduction of selenite to red elemental selenium by methane-oxidizing bacteria

Eswayah, A. S.; Hondow, N.; Scheinost, A. C.; Smith, T. J.; Gardiner, P. H. E.
Selenium (Se) is an essential element that is required for biosynthesis of selenocysteine, the 21st proteinogenic amino acid in prokaryotes and eukaryotes. Se is toxic at high concentrations for most living organisms.1 Toxic high levels of Se, particularly in the form of selenite (SeO32-) in the environment, may be of natural or anthropogenic origin. In the natural environments, Se is subject to various microbial transformations which are important for bioremediation of Se species.2
For example, microbial reduction of toxic SeO32- to insoluble elemental selenium (Se0) results in its removal from water. Also, the reduction and methylation of SeO42- and SeO32- is considered an effective detoxification process, since the products (dimethylselenide [DMSe] or dimethyldiselenide [DMDSe]) are 500 to 700 times less toxic than SeO42- or SeO32-.3
Although a wide range of microorganisms have been investigated for their ability to transform selenium species, to our knowledge, aerobic methane-oxidising bacteria (which are ubiquitous in the environment and have numerous potential applications in remediation of organic and inorganic pollutants) have not previously been investigated for their ability to transform Se compounds.
Keywords: methanotrophs, selenium
  • Poster
    VI International Conference on Environmental, Industrial and Applied Microbiology - BioMicroWorld 2015, 28.-30.10.2015, Barcelona, Spain

Permalink: https://www.hzdr.de/publications/Publ-22526
Publ.-Id: 22526


Bibliothekskonzeption als eine Möglichkeit, Konflikte zu vermeiden

Reschke, E.
Bis zum Jahr 2009 gab es immer wieder Diskussionen, ob es mit der Bibliothek am Helmholtz-Zentrum Dresen-Rossendorf weitergehen soll und wenn ja wie, insbesondere hinsichtlich der Personalstärke und des Raumbedarfs (Bibliothek als Ort in einer Forschungseinrichtung).
Daraufhin habe ich eine Bibliothekskonzeption für die Jahre 2010-2014 entwickelt, die zur Entscheidungsgrundlage wurde. Die Konzeption wurde von unserer Bibliothekskommission als richtungsweisend eingeschätzt und gegenüber dem Vorstand des Forschungszentrums zur Umsetzung empfohlen. Jetzt, 2015, können wir die vollständige Umsetzung der Konzeption berichten. Es gibt z.Z. keine Diskussionen um Bestand und Aufgaben der Bibliothek. Zwischen dem Vorstand, der Bibliothekskommission, unserem Zentralabteilungsleiter und der Bibliothek besteht Einvernehmen, dass sich zwar die Aufgaben der Bibliothek in ihrer Wichtung ändern, aber an der Notwendigkeit der Bibliothek vor Ort wird aktuell nicht gezweifelt.
Unterm Strich: Mit der gemeinsame Umsetzung der Konzeption wurde der Konflikt "Bibliothek brauchen wir-brauchen wir nicht" gelöst. Es entstand Planungssicherheit, die natürlich über den Zeitraum der Konzeptionsplanung hinaus weiter verteidigt/erkämpft werden muss.
Keywords: Strategisches Bibliotheksmanagement, Bibliothekskonzeption
  • Invited lecture (Conferences)
    35. Arbeitstagung der Arbeitsgemeinschaft der Spezialbibliotheken (ASpB), 23.-25.09.2015, Bonn, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-22525
Publ.-Id: 22525


Die Bibliothek: das Publikations- und Open Access Kompetenzzentrum am HZDR

Reschke, E.
Die Publikationsdatenbank im Helmholtz-Zentrum Dresden-Rossendorf wird seit 1992 geführt. Anfangs wurden nur bibliographische Daten erfasst. Mit den Jahren entstanden Bedürfnisse, mit diesen Daten mehr zu machen als Publikationslisten und es sollte keine doppelte Datenerfassung und Datenvorhaltung geben. Dafür mussten weitere Daten und Parameter in der einen Publikationsdatenbank erfasst werden. Der Genehmigungsworkflow wurde eingebaut, Controllingabfragen mussten möglich gemacht werden, wachsendes Berichtswesen erforderte zunehmende Flexibilität in den Abfragemöglichkeiten, Open Access Finanzierung, Verlinkung zur Datenarchivierung und weiteres. Ergebnis ist eine proprietäre Datenbankanwendung, basierend auf Oracle, die durch ihre Komplexität den Anforderungen aller beteiligten Akteure: Wissenschaftler, Bibliothek, wissenschaftliches Controlling, Institutsdirektoren und Vorstand, gerecht werden kann. Im Vortrag werden die verschiedenen Funktionen und die Organisation der Publikationsdatenbank vorgestellt.
Keywords: Library, Open Access, Publication database, Bibliothek, Publikationsdatenbank
  • Invited lecture (Conferences)
    Fraunhofer Arbeitstagung Bibliotheks- und Informationswesen 2015, 19.-22.10.2015, Fulda, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-22524
Publ.-Id: 22524


Verification of Master Curve testing on mini-0.16T-C(T) specimens

Viehrig, H.-W.; Houska, M.; Yamamoto, M.
Fracture toughness evaluation by the Master Curve method using 4-mm-thick miniature compact tension (mini-C(T)) specimens has been proposed. There were round robin exercises to validate the reference temperature, T0, determined on mini-C(T) of RPV base and weld metal. The HZDR has contributed to these round robin exercises. In addition to the mandatory testing, the distribution of the cleavage initiation sites over the crack front was determined. The mini-C(T) testing was also verified on RPV base metal 22 NiMoCr 3-7 from the lower ring of the non-commissioned Biblis C RPV. The fracture toughness values and therewith evaluated reference temperatures, T0, measured on 1T-, 0.5T-, 0.25T and 0.16T-C(T) specimens are compared. The results show that the T0 values determined with C(T) specimens of different size scatter within one standard deviation according to ASTM E1921. The testing of mini-C(T) specimens machined from the broken halves of Charpy specimens is a promising option to determine fracture toughness values of already tested surveillance specimens. The advantage of using mini-C(T) specimens is that material from the weld region can be investigated directly.
Keywords: compact tension specimen, Master Curve approach, fracture toughness, reference temperature
  • Lecture (Conference)
    International workshop “RPV Embrittlement and Surveillance Programmes”, 13.-15.10.2015, Prag, Tschechische Republik

Permalink: https://www.hzdr.de/publications/Publ-22523
Publ.-Id: 22523


Immobilisierung von Tc(VII)/Tc(IV) an Eisenphasen

Spranger, F.
Die Immobilisierung von Tc(VII)/Tc(IV) an den Eisenphasen Magnetit und Siderit wurde mittels Batch-Sorptionsversuchen, ATR FT-IR-Spektroskopie und Röntgenabsorptionsspektroskopie untersucht.
Keywords: Technetium, Magnetite, Siderite
  • Bachelor thesis
    TU Dresden, 2015
    Mentor: Dr. Katja Schmeide / Prof. Dr. Thorsten Stumpf
    43 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-22522
Publ.-Id: 22522


Speciation Studies of Metals in Trace Concentrations: The Mononuclear Uranyl(VI) Hydroxo Complexes

Drobot, B.; Bauer, A.; Steudtner, R.; Tsushima, S.; Bok, F.; Patzschke, M.; Raff, J.; Brendler, V.
A direct luminescence spectroscopic experimental setup for the determination of complex stability constants of mononuclear uranyl(VI) hydrolysis species is presented. The occurrence of polynuclear species is prevented using a low uranyl(VI) concentration of 10-8M (2.4 ppb). Time-resolved laser-induced fluorescence spectra were recorded in a pH range from 3 to 10.5. Deconvolution with parallel factor analysis (PARAFAC) resulted in three hydrolysis complexes. A tentative assignment was based on thermodynamic calculations: UO2+2 - 1:0 (aquo ion), UO2(OH)+ - 1:1, UO2(OH)2 - 1:2, UO2(OH)-3 - 1:3. An implementation of a Newton-Raphson algorithm into PARAFAC allowed a direct extraction of complex stability constants during deconvolution yielding log(ß1 M, 1 °C)1:1 =-4.4, log(ß1 M, 1 °C)1:2 =-11.7, log(ß1 M, 1 °C)1:3 =-21.6. Extrapolation to standard conditions gave: log(ß0)1:1 =-3.7, log(ß0)1:2 =-10.4 and log(ß0)1:3 =-20.1. Luminescence characteristics (band position, lifetime) of the individual mononuclear hydroxo species were derived to serve as reference data set for further investigations. A correlation of luminescence spectroscopic features with Raman frequencies was demonstrated for the mononuclear uranyl(VI) hydroxo complexes for the first time. Thereby a signal-to-structure correlation was achieved and the complex assignment validated.

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Permalink: https://www.hzdr.de/publications/Publ-22521
Publ.-Id: 22521


All-optical free electron lasers -- realizable with Traveling-wave Thomson scattering

Debus, A.; Steiniger, K.; Bussmann, M.; Irman, A.; Jochmann, A.; Pausch, R.; Roeser, F.; Schramm, U.; Sauerbrey, R.
Optical free-electron lasers (OFEL) based on the Traveling-wave Thomson scattering (TWTS) geometry are realizable using existing petawatt class laser systems and electron beams from either conventional or Laser-wakefield accelerators. Such OFELs operate in the EUV to x-ray range, while at the same time remaining compact.

Such TWTS OFELs optimally exploit the high spectral photon density in high-power laser pulses by spatially stretching the laser pulse and overlapping it with the electrons in a side scattering setup. The introduction of a laser pulse-front tilt provides for interaction lengths appropriate for FEL operation, so that beam electrons witness an undulator field of near-constant strength and wavelength over hundreds to thousands of undulator periods, thus giving enough time for self-amplified spontaneous emission (SASE) to seed the FEL instability and the realization of large laser gains.

Based on results from our analytical 1.5D-theory and numerical investigations, we discuss scaling laws and show using example scenarios that TWTS OFELs can be realized with existing RF sources such as ELBE at HZDR as well as LWFA electrons. We detail the necessary equipment for a TWTS OFEL experiment and discuss how current experimental limitations affect the design.
Keywords: optical FEL, X-ray, free-electron laser, TWTS, Traveling-wave Thomson scattering
  • Lecture (Conference)
    2nd European Advanced Accelerator Concepts Workshop (EAAC 2015), 13.-19.09.2015, La Biodola, Isola d'Elba, Italien

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Permalink: https://www.hzdr.de/publications/Publ-22520
Publ.-Id: 22520


Ultra-compact all-optical FELs and Compton sources

Debus, A.; Steiniger, K.; Pausch, R.; Bussmann, M.; Krämer, J.; Jochmann, A.; Irman, A.; Schramm, U.
The interaction of an electron beam emerging from laser wakefield accelerators with an optical undulator allows for the realization of ultra-compact all-optical FELs and Compton sources using existing high-power lasers.
This presentation will review the various schemes considered to date with emphasis on both expected performance of the emitted radiation and challenges to face in terms of electron beam and laser pulse parameters.
Keywords: optical free-electron laser, OFEL, Compton source, Thomson source, FEL, free-electron laser, X-ray FEL
  • Invited lecture (Conferences)
    2nd European Advanced Accelerator Concepts Workshop 2015 (EAAC 2015), 13.09.-19.10.2015, La Biodola, Isola d'Elba, Italien

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Permalink: https://www.hzdr.de/publications/Publ-22519
Publ.-Id: 22519


Simultaneous β1 integrin-EGFR targeting and radiosensitization of human head and neck cancer.

Eke, I.; Zscheppang, K.; Dickreuter, E.; Hickmann, L.; Mazzeo, E.; Unger, K.; Krause, M.; Cordes, N.
BACKGROUND:

Signaling from integrins and receptor tyrosine kinases (RTKs) contributes substantially to therapy resistance of malignant tumors. We investigated simultaneous β1 integrin-epidermal growth factor receptor (EGFR) targeting plus radiotherapy in human head and neck squamous cell carcinomas (HNSCCs).
METHODS:

Ten HNSCC cell lines were grown in three-dimensional laminin-rich extracellular matrix cell cultures and two of them as tumor xenografts in nude mice (n = 12-16 per group). Targeting of β1 integrin and EGFR with monoclonal inhibitory antibodies (AIIB2 and cetuximab, respectively) was combined with x-ray irradiation. Clonogenic survival, tumor growth, and tumor control (evaluated by Kaplan-Meier analysis), apoptosis, phosphoproteome (interactome, network betweeness centrality analysis), receptor expression (immunohistochemistry), and downstream signaling (western blotting) were assessed. Various mutants of the integrin signaling mediator focal adhesion kinase (FAK) were employed for mechanistic studies. All statistical tests were two-sided.
RESULTS:

Compared with β1 integrin or EGFR single inhibition, combined β1 integrin-EGFR targeting resulted in enhanced cytotoxicity and radiosensitization in eight out of 10 tested HNSCC cell lines, which responded with an FAK dephosphorylation after β1 integrin inhibition. In vivo, simultaneous anti-β1 integrin/anti-EGFR treatment and radiotherapy of UTSCC15 responder xenografts enabled better tumor control compared with anti-EGFR monotherapy and irradiation (hazard ratio [HR] = 6.9, 95% confidence interval [CI] = 1.6 to 30.9, P = .01), in contrast to the SAS nonresponder tumor model (HR = 0.9, 95% CI = 0.4 to 2.3, P = .83). Mechanistically, a protein complex consisting of FAK- and Erk1-mediated prosurvival signals for radiation resistance, which was effectively compromised by β1 integrin and EGFR blocking.
CONCLUSIONS:

Concomitant targeting of β1 integrin and EGFR seems a powerful and promising approach to overcome radioresistance of HNSCCs.

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Permalink: https://www.hzdr.de/publications/Publ-22518
Publ.-Id: 22518


Radiation-induced lung damage - Clinical risk profiles and predictive imaging on their way to risk-adapted individualized treatment planning?

Ebert, N.; Baumann, M.; Troost, E. G.
there ist no abstract

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Permalink: https://www.hzdr.de/publications/Publ-22517
Publ.-Id: 22517


Complex formation of europium and curium with the digestive enzyme alpha-amylase

Barkleit, A.; Heller, A.; Bernhard, G.
In case of the incorporation of radioactive heavy metal ions, they would represent a serious health risk to humans due to their chemo- and/or radiotoxicity. Trivalent actinides (An(III)) like Am(III) or Cm(III) are man-made radioactive elements exclusively generated in nuclear reactors, whilst non-radioactive lanthanides (Ln(III)) are naturally occurring elements having wide technological and medical applications. These heavy metals have a potential risk of intake into humans with different pathways. Since Ln(III) and An(III) are considered to have no significant essential function in the human body, little is known about their biochemical behaviour from the uptake, in-vivo transport to the final accumulation or excretion.
Our recent studies on the speciation of U(VI) and Cm(III) in body fluids (e.g., saliva) suggested α-amylase as a potential binding partner of these actinides, which would finally affect the biochemical behaviour of these elements in-vivo. The enzyme α-amylase is one of the major enzymes in salivary and pancreatic secretions of mammals and catalyses the hydrolysis of polysaccharides like starch or glycogen. In order to further understand the potential role of α-amylase in the in-vivo speciation and complexation of Ln(III) and An(III), we investigated the complexation of Eu(III) and Cm(III) with α-amylase over a wide pH range by using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Based on the obtained spectroscopic results, stability constants were determined at ambient and physiological temperature. The data were further extrapolated to infinite dilution to make the obtained data compatible with the existing thermodynamic database. The speciation of Eu(III) and Cm(III) in the saliva studied were determined based on these new data and will be presented.
  • Lecture (Conference)
    International Conference on Radioanalytical and Nuclear Chemistry (RANC-2016), 10.-15.04.2016, Budapest, Hungary

Permalink: https://www.hzdr.de/publications/Publ-22515
Publ.-Id: 22515


SABR in NSCLC--the beginning of the end or the end of the beginning?

Brada, M.; Pope, A.; Baumann, M.
there is no Abstract

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Permalink: https://www.hzdr.de/publications/Publ-22514
Publ.-Id: 22514


Interaction of extracellular S100A4 with RAGE prompts prometastatic activation of A375 melanoma cells

Herwig, N.; Belter, B.; Wolf, S.; Haase-Kohn, C.; Pietzsch, J.
S100A4, a member of the S100 protein family of EF-hand calcium-binding proteins, is overexpressed in various tumour entities, including melanoma, and plays an important role in tumour progression. Several studies in epithelial and mesenchymal tumours revealed a correlation between extracellular S100A4 and metastasis. However, exact mechanisms how S100A4 stimulates metastasis in melanoma are still unknown. From a pilot experiment on baseline synthesis and secretion of S100A4 in human melanoma cell lines, which are in broad laboratory use, A375 wild-type cells and, additionally, newly generated A375 cell lines stably transfected with human S100A4 (A375-hS100A4) or human receptor for advanced glycation endproducts (A375-hRAGE), were selected to investigate the influence of extracellular S100A4 on cell motility, adhesion, migration and invasion in more detail. We demonstrated that A375 cells actively secrete S100A4 in the extracellular space via an endoplasmic reticulum-Golgi-dependent pathway. S100A4 overexpression and secretion resulted in prometastatic activation of A375 cells. Moreover, we determined the influence of S100A4-RAGE interaction and its blockade on A375, A375-hS100A4, A375-hRAGE cells, and showed that interaction of RAGE with extracellular S100A4 contributes to the observed activation of A375 cells. This investigation reveals additional molecular targets for therapeutic approaches aiming at blockade of ligand binding to RAGE or RAGE signalling to inhibit melanoma metastasis.
Keywords: Calcium-binding proteins; Cancer metastasis; ER-Golgi-dependent secretion pathway; S100 protein secretion; Soluble receptor for advanced glycation endproducts

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Permalink: https://www.hzdr.de/publications/Publ-22512
Publ.-Id: 22512


Physical modelling of temperature fluctuations in a high aspect ratio model of the Czochralski crystal growth

Pal, J.; Cramer, A.; Grants, I.; Eckert, S.; Gerbeth, G.
A low temperature liquid metal model of the Czochralski (CZ) crystal growth process is considered experimentally for a high aspect ratio. Temperature fluctuations close to the edge of the model crystal are studied under the action of a rotating magnetic field (RMF) and/or rotation of the model crystal. A rotation of thermal structures is observed which loses its periodicity at sufficiently high strengths of the RMF. This finding is in qualitative agreement with previous findings in Rayleigh-Bénard (RB) cells. Opposing to that more generic case, the remaining amplitude of the temperature fluctuations stays significantly higher. I.e., the suppression of the fluctuations, which are detrimental to the growth of a mono-crystal, is weaker in the model under investigation.
Keywords: Rayleigh-Bénard convection, Large-scale temperature oscillation, Magnetohydrodynamics, Electromagnetic stirring, Czochralski crystal growth, Model Experiment

Permalink: https://www.hzdr.de/publications/Publ-22511
Publ.-Id: 22511


Physical model of Czochralski crystal growth in a horizontal magnetic field

Pal, J.; Grants, I.; Eckert, S.; Gerbeth, G.
A low temperature liquid metal model of the Czochralski crystal growth process is considered experimentally under conditions of high aspect ratio. In this paper we focus on the influence of a horizontal magnetic field (HMF) on the radial flow field and present first results from related model experiments. The flow is measured by means of the ultra-sound Doppler velocimetry (UDV).
Keywords: Czochralski Crystal Growth, Horizontal Magnetic Field, Flow Measurements
  • Contribution to proceedings
    8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 12.10.-16.12.2015, Cannes, France
    Proceedings of the 8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 978-2-9553861-0-1, 41-44
  • Lecture (Conference)
    8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 12.-16.10.2015, Cannes, France

Permalink: https://www.hzdr.de/publications/Publ-22510
Publ.-Id: 22510


Experimental study of the flow driven by combined AC magnetic fields using a novel ultrasound array system

Pal, J.; Cramer, A.; Franke, S.; Eckert, S.; Nauber, R.; Thieme, N.; Büttner, L.; Czarske, J.
Ultrasound velocity measurements were performed in a liquid metal flow (GaInSn) inside a cubic vessel. The flow was driven by the combined action of a rotating (RMF) and a travelling magnetic field (TMF) leading to an inherent three-dimensional electromagnetic force distribution in the fluid. As a result flow structures develop which are essentially determined by the frequency difference and the strength relation of both fields. The driving force is stationary for identical frequencies whereas it undergoes a slow temporal modulation in case of slightly varying frequencies. Beside the magnetic field parameter the alignment of the TMF’s to the fluid volume’s axis plays a crucial role. A novel ultrasound array system was used in the present study to measure two velocity components in two perpendicular planes (2d-2c) simultaneously. This contribution reports on the influence of axial alignment on the flow, and on the flow dynamics resulting from slightly different field frequencies of the RMF and the TMF.
Keywords: Ultrasound Sensor Array, Flow Field Measurements, Magnetohydrodynamics, Electromagnetic Stirring
  • Contribution to proceedings
    8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 12.-16.10.2015, Cannes, France
    Proceedings of the 8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 978-2-9553861-0-1, 365-368
  • Lecture (Conference)
    8th International Conference on Electromagnetic Processing of Materials, EPM 2015, 12.-16.10.2015, Cannes, France

Permalink: https://www.hzdr.de/publications/Publ-22509
Publ.-Id: 22509


Structural properties and charge distribution of the sodium uranium, neptunium and plutonium ternary oxides: a combined X-ray diffraction and XANES study

Smith, A. L.; Martin, P.; Prieur, D.; Scheinost, A. C.; Raison, P. E.; Cheetham, A. K.; Konings, R. J. M.
The structural properties of the sodium actinide ternary oxides are reviewed in this work, and general trends among the series U-Np-Pu are identifed. A Rietveld refnement of monoclinic Na2PuO3, in space group C2~c, is reported for the first time, and the unsuspected existence of Na2NpO3 is revealed. In addition, the charge distribution in alpha-Na2UO4, Na3NpO4, alpha-Na2NpO4, Na4NpO5, Na5NpO6, Na2PuO3, Na4PuO5, and Na5PuO6 is investigated using X-ray Absorption Near-Edge Structure (XANES) spectroscopy at the U-L3, Np-L3, and Pu-L3 edges, respectively. In contrast to measurements in solution, the number of XANES data in the literature for neptunium and plutonium solid phases with a valence state higher than (IV) is very limited. The present results cover a wide range of oxidation states, namely (IV) to (VII), and can serve as a reference databank for future investigations. Finally, the sodium actinide series show a variety of local coordination geometries, and correlations between shape of the XANES spectra and local structural environment are discussed.
Keywords: Neptunium Plutonium ternary oxides XANES XRD Rietveld sodium-cooled fast-neutron reactor

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Permalink: https://www.hzdr.de/publications/Publ-22508
Publ.-Id: 22508


Remote Sensing-Based Assessment of the Variability of Winter and Summer Precipitation in the Pamirs and Their Effects on Hydrology and Hazards Using Harmonic Time Series Analysis

Pohl, E.; Gloaguen, R.; Seiler, R.
Moisture supply in the Pamir Mountains of Central Asia significantly determines the hydrological cycle and, as a result, impacts the local communities via hazards or socioeconomic aspects, such as hydropower, agriculture and infrastructure. Scarce and unreliable in situ data prevent an accurate assessment of moisture supply, as well as its temporal and spatial variability in this strongly-heterogeneous environment. On the other hand, a clear understanding of climatic and surface processes is required in order to assess water resources and natural hazards. We propose to evaluate the potential of remote sensing and regional climate model (RCM) data to overcome such issues.
Difficulties arise for the direct analysis of precipitation if the events are sporadic and when the amounts are low. We hence apply a harmonic time series analysis (HANTS) algorithm to derive spatio-temporal precipitation distributions and to determine regional boundaries delimiting areas where winter or summer precipitation dominate moisture supply. We complement the study with remote sensing-based products, such as temperature, snow cover and liquid water equivalent thickness. We find a strong intra- and inter-annual variability of meteorological parameters that result in strongly variable water budget and water mobilization. Climatic variability and its effects on floods and droughts are discussed for three outstanding years. The in-house developed HANTS toolbox is a promising instrument to unravel periodic signals in remote sensing time series, even in complex areas, such as the Pamir.
Keywords: potential of remote sensing, regional climate model (RCM), harmonic time series analysis (HANTS) algorithm

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Permalink: https://www.hzdr.de/publications/Publ-22507
Publ.-Id: 22507


Multiphase flow modelling in moderately rotating inclined porous media

Härting, H.-U.; Lange, R.; Schubert, M.
Advective and diffusive multiphase flows through vertical porous media are well examined and discussed in the scientific literature. However, uncommon configurations with inclined porous media are examined to a less extent, while advanced configurations with superimposed motion have hitherto only been addressed scarcely. An example for such configuration is the inclined rotating tubular fixed bed reactor, which is a novel intensified multiphase reactor for heterogeneous catalytic gas-liquid-solid reactions (H.-U. Härting, R. Lange, F. Larachi, M. Schubert, Chem. Eng. J. 2015, 281, 931).
For the prediction of liquid saturation and two-phase pressure drop in inclined and moderately fast rotating confined porous media, a two-fluid model is presented. The model is one-directional, isothermal and considers incompressible Newtonian fluids. To account for the interphase momentum transfer, adopted Ergun-type closures are formulated taking the peculiarities of stratified, dispersed and annular flow into account. The effects of inclination and rotation are incorporated as additional body forces, whereby inclination is taken into account by the longitudinal gravity component and an semi-empirical closure for the complex effects of the rotational velocity is presented. The applicability of the model is validated against experimental liquid saturation and two-phase pressure drop data.
Keywords: multiphase flow, porous media, reactor inclination, rotating fixed bed, projection method

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Permalink: https://www.hzdr.de/publications/Publ-22506
Publ.-Id: 22506


Radiosensitization of NSCLC cells by EGFR inhibition is the result of an enhanced p53-dependent G1 arrest.

Kriegs, M.; Gurtner, K.; Can, Y.; Brammer, I.; Rieckmann, T.; Oertel, R.; Wysocki, M.; Dorniok, F.; Gal, A.; Grob, T. J.; Laban, S.; Kasten-Pisula, U.; Petersen, C.; Baumann, M.; Krause, M.; Dikomey, E.
PURPOSE:

How EGF receptor (EGFR) inhibition induces cellular radiosensitization and with that increase in tumor control is still a matter of discussion. Since EGFR predominantly regulates cell cycle and proliferation, we studied whether a G1-arrest caused by EGFR inhibition may contribute to these effects.
MATERIALS AND METHODS:

We analyzed human non-small cell lung cancer (NSCLC) cell lines either wild type (wt) or mutated in p53 (A549, H460, vs. H1299, H3122) and HCT116 cells (p21 wt and negative). EGFR was inhibited by BIBX1382BS, erlotinib or cetuximab; p21 was knocked down by siRNA. Functional endpoints analyzed were cell signaling, proliferation, G1-arrest, cell survival as well as tumor control using an A549 tumor model.
RESULTS:

When combined with IR, EGFR inhibition enhances the radiation-induced permanent G1 arrest, though solely in cells with intact p53/p21 signaling. This increase in G1-arrest was always associated with enhanced cellular radiosensitivity. Strikingly, this effect was abrogated when cells were re-stimulated, suggesting the initiation of dormancy. In line with this, only a small non-significant increase in tumor control was observed for A549 tumors treated with fractionated RT and EGFR inhibition.
CONCLUSION:

For NSCLC cells increase in radiosensitivity by EGFR inhibition results from enhanced G1-arrest. However, this effect does not lead to improved tumor control because cells can be released from this arrest by re-stimulation.
Keywords: Cell cycle; EGFR inhibition; G1 arrest; NSCLC; Radiosensitization; p53

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Permalink: https://www.hzdr.de/publications/Publ-22505
Publ.-Id: 22505


Radio-chemotherapy improves survival in IDH-mutant, 1p/19q non-codeleted secondary high-grade astrocytoma patients.

Juratli, T. A.; Lautenschläger, T.; Geiger, K. D.; Pinzer, T.; Krause, M.; Schackert, G.; Krex, D.
Isocitrate dehydrogenase (IDH) mutations are beginning to drive decisions on therapy for glioma patients. Here we sought to determine the impact of adjuvant treatment in patients with IDH-mutant, 1p/19q non-codeleted secondary high-grade astrocytoma (sHGA) WHO grades III/IV. Clinical data of 109 sHGA patients grades III/IV, in addition to IDH mutation-, 1p/19q-codeletion- and MGMT-promoter methylation status-were retrospectively analyzed. Survival analysis in relation to adjuvant treatment modalities and molecular profiling were performed. Out of 109 patients, 88 patients (80.7 %) harbored IDH mutations, 30 patients had a 1p/19q-codeletion (27.5 %) and 69 patients (63.3 %) exhibited a methylated MGMT-promoter status. At a median follow-up of 9.8 years, 62 patients (57 %) died. The postsurgical treatment included: radio-chemotherapy (RT-CT; 54.5 %), RT alone (19.3 %), and CT alone (22.7 %). The median overall survival (OS) in the entire group was 3.4 years (1.9-6.7 years). Patients who received RT-CT had a significantly longer OS compared with those who underwent RT alone (6.5 vs. 1.2 years, HR 0.35, CI 0.32-0.51, p = 0.011). In the IDH-mutant 1p/19q non-codeleted sHGA subgroup the RT-CT cohort had a significantly longer OS in comparison to the RT cohort (6.4 vs. 1.2 years, HR 2.7, CI 1.1-6.5, p = 0.022). In the stepwise multivariable Cox model for OS of all 88 IDH-mutant sHGA patients, survival was strongly associated with only one factor, namely, adjuvant RT-CT at diagnosis of a sHGA. This retrospective long-term study demonstrates that RT and CT (mostly PCV) significantly improves progression-free and overall survival in IDH-mutant secondary high-grade astrocytoma patients, regardless of 1p/19q-codeletion status.
Keywords: 1p/19q-codeletion; IDH mutation; PCV MGMT-promoter status; Radio-chemotherapy; Secondary high-grade astrocytomas

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Permalink: https://www.hzdr.de/publications/Publ-22504
Publ.-Id: 22504


Cytotoxic and radiosensitizing effects of FAK targeting in human glioblastoma cells in vitro.

Storch, K.; Sagerer, A.; Cordes, N.
Glioblastoma multiforme (GBM) is a highly aggressive and extremely lethal cancer and novel molecular therapies are required for optimized multimodal therapy regimes. While focal adhesion kinase (FAK) is regarded as a therapeutic target, its radiosensitizing potential remains to be elucidated in glioblastoma. Thus, FAK was inhibited using the pharmaco-logical inhibitor TAE226 and cytotoxicity and radiosensitization of glioblastoma cells were investigated in vitro. Monolayer and suspension cell cultures of a panel of glioblastoma cell lines (A172, LN229, U87MG, U138MG, U343MG, DD-HT7607, and DD-T4) were treated with increasing TAE226 concentrations (0-10 µM) alone or in combination with X-rays (0-6 Gy). Subsequently, clonogenic cell survival, expression and the phosphorylation of FAK downstream signaling, apoptosis and autophagy were analyzed. Efficient FAK inhibition by TAE226 mediated significant cytotoxicity and reduced sphere formation in a dose- and time-dependent manner. Two out of seven glioblastoma cell lines showed radiosensitization. Apoptotic induction by TAE226 was cell line-dependent. The results demonstrated that pharmacological FAK inhibitor TAE226 efficiently reduced clonogenicity and sphere formation in glioblastoma cells without generally modifying their radiosensitivity. However, future studies are necessary to define the potential of FAK inhibition by TAE226 or other pharmacological inhibitors in combination with radiochemotherapy.

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Permalink: https://www.hzdr.de/publications/Publ-22503
Publ.-Id: 22503


Fabrication and characterization of oxide dispersion strengthened (ODS) 14Cr steels consolidated by means of hot isostatic pressing, hot extrusion and spark plasma sintering

Hilger, I.; Boulnat, X.; Hoffmann, J.; Testani, C.; Bergner, F.; de Carlan, Y.; Ferraro, F.; Ulbricht, A.
Ferritic ODS 14Cr steels are one of the options for future nuclear and non-nuclear energy applications, in particular for components exposed to higher operation temperatures. In order to better exploit the potential advantages of ODS ferritic steels, such as improved creep strength and damage tolerance (with respect to non-ODS high-chromium steels) along with excellent oxidation resistance, a broader scientific and technical background is required. The present collaborative approach aimed to contribute to this background with respect to both fabrication issues and nano-/microstructurally based understanding of the resulting properties. In particular, the feasibility of ODS steel fabrication by means of spark plasma sintering on a semi-industrial scale was to be demonstrated. Parameter variations related to mechanical alloying, consolidation and thermal/mechanical treatments were covered. Hot extrusion was successfully applied to produce a 2.5 kg batch of ODS steel. Spark plasma sintering was scaled up towards semiindustrial 0.5 kg batches. A set of characterization techniques including Small-Angle Neutron Scattering, Transmission Electron Microscopy, Atom-Probe Tomography, Electron Probe Micro-Analysis, Electron Back-Scatter Diffraction and Transmission Kikuchi Diffraction as well as mechanical testing were applied to characterize the materials at different scales and stages of the fabrication process and to underpin the findings, such as a pronounced bimodality of grain size distributions, by observation-based understanding.
Keywords: ODS steel, Mechanical alloying, Hot extrusion, Spark plasma sintering, microstructure, mechanical testing

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Permalink: https://www.hzdr.de/publications/Publ-22502
Publ.-Id: 22502


Materialien für morgen: Energieeffiziente Prozesse in der Informationstechnologie

Gemming, S.
Kurzer Festvortrag bei der Feier 20 Jahre Helmholtz - 20 Highlights
Keywords: energy, resistive, memristor, self-organization, self-assembly, simulation
  • Invited lecture (Conferences)
    20 Jahre Helmholtz, 25.06.2015, Berlin Adlershof, WISTA, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22501
Publ.-Id: 22501


Dynamic processes in materials for energy conversion and storage

Gemming, S.
Modern material combinations, which we use for converting, storing and saving energy, exploit the synergistic effects of multi-component systems to achieve functionalities beyond those of the single constituents alone. Steps towards a rational design of such material systems have increasingly inspired research activities both from experiment and theory. With the considerable increase of computational resources, simulations have successfully started to bridge the gap between idealized, rather specific theoretical concepts and experimental realization for system length and time scales, which reflect specific physical processes involved in energy saving, conversion, and storage. I will present examples from recent work which span the range the range from nano-scale battery effects in thin multifunctional oxide films of spongy structures by spinodal decomposition of silicon monoxide for storage and conversion to formation and stability of anti-wear coatings for energy efficient applications. Those studies illustrate recent developments to arrive at a truly scale- adapted modeling of energy materials.
Keywords: energy, density functional theory, energy conversion, energy storage
  • Invited lecture (Conferences)
    International Colloquium on the Simulation of Energy Materials, 12.06.2015, Jülich, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22500
Publ.-Id: 22500


Microscopic processes in data and energy storage - considerations based on multiscale modeling

Gemming, S.
There is no abstract available.
Keywords: density functional theory, memristive, resistive, strontium titanate, tintaniom oxide
  • Invited lecture (Conferences)
    Seminarreihe der FSU Jena, 23.01.2015, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22499
Publ.-Id: 22499


Theoretical investigation of an in situ k-restore process for damaged ultra-low-k materials based on plasma enhanced fragmentation

Förster, A.; Wagner, C.; Gemming, S.; Schuster, J.
The authors present theoretical investigations of a k-restore process for damaged porous ultra-low-k (ULK) materials. The process is based on plasma enhanced fragmented silylation precursors to replace k-value damaging, polar Si-OH and Si-H bonds by k-value lowering Si-CH3 bonds. The authors employ density functional theory to determine the favored fragments of silylation precursors and show the successful repair of damaged bonds on our model system.
Keywords: density-functional theory, molecules, adsorption, passivation, molecular dynamics

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Permalink: https://www.hzdr.de/publications/Publ-22498
Publ.-Id: 22498


Near-surface hydrogen depletion of diamond-like carbon films produced by direct ion deposition

Markwitz, A.; Gupta, P.; Mohr, B.; Hübner, R.; Leveneur, J.; Zondervan, A.; Becker, H.-W.
Amorphous atomically flat diamond-like carbon (DLC) coatings were produced by direct ion deposition using a system based on a Penning ion source, butane precursor gas and post acceleration. Hydrogen depth profiles of the DLC coatings were measured with the 15N R-NRA method using the resonant nuclear reaction 1H(15N,alpha gamma)12C (Eres = 6.385 MeV). The films produced at 3.0-10.5 kV acceleration voltage show two main effects. First, compared to average elemental composition of the film, the near-surface region is hydrogen depleted. The increase of the hydrogen concentration by 3% from the near-surface region towards the bulk is attributed to a growth model which favours the formation of sp2 hybridised carbon rich films in the film formation zone. Secondly, the depth at which the maximum hydrogen concentration is measured increases with acceleration voltage and is proportional to the penetration depth of protons produced by the ion source from the precursor gas. The observed effects are explained by a deposition process that takes into account the contributions of ion species, hydrogen effusion and preferential displacement of atoms during direct ion deposition.
Keywords: Diamond-like carbon, Hydrogen depletion, Depth profile, Nuclear reaction analysis, Growth process

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Permalink: https://www.hzdr.de/publications/Publ-22497
Publ.-Id: 22497


High Energy Radial Deposition of Diamond-Like Carbon Coatings

Suschke, K.; Hübner, R.; Murmu, P. P.; Gupta, P.; Futter, J.; Markwitz, A.
Diamond-like carbon (DLC) coatings were deposited with a new direct ion deposition system using a novel 360 degree ion source operating at acceleration voltage between 4 and 8 kV. Cross-sectional TEM images show that the coatings have a three layered structure which originates from changes in the deposition parameters taking into account ion source condition, ion current density, deposition angles, ion sputtering and ion source movement. Varying structural growth conditions can be achieved by tailoring the deposition parameters. The coatings show good promise for industrial use due to their high hardness, low friction and excellent adhesion to the surface of the samples.
Keywords: diamond-like carbon; direct ion deposition; anode layer ion source; amorphous carbon; TEM

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Permalink: https://www.hzdr.de/publications/Publ-22496
Publ.-Id: 22496


ELBE SRF Gun II – Emittance Compensation Schemes

Vennekate, H.; Arnold, A.; Jansen, D.; Kneisel, P.; Lu, P.; Murcek, P.; Teichert, J.; Xiang, R.
In May 2014 the first SRF photo injector at HZDR has been replaced by a new gun, featuring a new resonator and cryostat. The intention for this upgrade has been to reach for higher beam energies, bunch charges and therefore an increased average beam current, which is to be injected into the superconducting, CW ELBE accelerator, where it can be used for multiple purposes, such as THz generation or Compton back-scattering. Because of the increased bunch charge of this injector compared to its predecessor, it demands upgrades of the existing and/or novel approaches to alleviate the transverse emittance growth. One of these methods is the integration of a superconducting solenoid into the cryostat. Another method, the so called RF focusing, is realized by displacing the photo cathode’s tip and retracting it from the last cell of the resonator. In this case, part of the accelerating field is sacrificed for a better focus of the electron bunch right at the start of its generation. Besides particle tracking simulations, a recent study, investigating on the exact position of the cathode tip with respect to the cell’s back plane after tuning and cool down, has been performed.
Keywords: Emittance, ELBE, SRF Gun
  • Open Access Logo Contribution to proceedings
    17th International Conference on RF Superconductivity, 13.-18.10.2015, Whistler, Canada

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Permalink: https://www.hzdr.de/publications/Publ-22495
Publ.-Id: 22495


High-field terahertz spectroscopy at HZDR

Schneider, H.
There is no abstract.
Keywords: terahertz spectroscopy, free-electron laser
  • Lecture (others)
    Seminar, Institut Saint-Louis, 18.09.2015, Saint-Louis, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-22493
Publ.-Id: 22493


Two-photon quantum well photodetectors for the THz regime

Franke, C.; Walther, M.; Helm, M.; Schneider, H.
Two-photon quantum-well photodetector devices designed for transition energies corresponding to 3 – 6 THz have been realized and intersubband energies were verified by photocurrent spectroscopy. Super-linear but not ideally quadratic behavior has been demonstrated by interferometric autocorrelation experiments using narrow-band terahertz pulses from the free-electron laser FELBE. With decreasing operation frequency, detector operation is progressively limited to low applied fields because of pronounced breakdown phenomena of the conductivity. This work has been supported by the Deutsche Forschungsgemeinschaft, project number SCHN 1127/2-1.
Keywords: terahertz two-photon intersubband absorption, quadratic detection, autocorrelation, GaAs/AlGaAs quantum well
  • Lecture (Conference)
    The 13th International Conference on Intersubband Transitions in Quantum Wells (ITQW'2015), 06.-11.09.2015, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-22492
Publ.-Id: 22492


Strong electroluminescence from terbium-doped metal-insulator-semiconductor structures

Berencen, Y.; Braun, M.; Garrido, B.; Hiller, D.; Liu, B.; Ramirez, J. R.; Sun, J.; Wutzler, R.; Helm, M.; Skorupa, W.
Integrated photonics is a key technology of the 21st century, and the electrically driven, integrated light emitter is an important building block, but difficult to realize. Thus, an enormous variety of different materials and material systems have been investigated in the past, ranging from the various approaches to integrate III-V semiconductors to the different types of Si-based light emission. Within the latter group rare earth (RE) implanted MOS structures feature a high conformity with standard CMOS processes combined with the excellent optical properties of RE elements. The present contribution discusses the problems of Si-based light emitters at the example of RE-doped MOS structures, and compares various light emitter designs and their potential to overcome these problems.
In detail, the power efficiency, the operation lifetime and the operation voltage of Tb- MOS structures are investigated. The main electroluminescence excitation mechanism is impact excitation of hot electron which plays an ambivalent role: efficient excitation is often related with efficient defect creation. In addition, a dark zone close to the injecting interface limits the scalability towards low voltages. The excitation mechanism und thus the performance of the light emitter is affected by the structure and composition of the dielectric stack of the MOS structure. Within this study, several host materials for the RE ions, namely stoichiometric and Si-rich silicon oxide or silicon nitride; different fabrication methods, namely plasma enhanced chemical vapour deposition, ion implantation and atomic layer deposition; and the use of additional buffer or injection layers are investigated.
Keywords: terbium, Si-based light emitters, electroluminescence, atomic layer deposition
  • Invited lecture (Conferences)
    Freiberg Silicon Days 2015, 18.-19.06.2015, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22491
Publ.-Id: 22491


Temperature distribution during flash lamp annealing of thin film multilayer systems

Rebohle, L.; Schumann, T.; Prucnal, S.; Skorupa, W.; Henke, T.
Flash lamp annealing (FLA) is a modern annealing technique which takes advantage of the millisecond- and microsecond time scale. However, in many cases a direct temperature determination is sophisticated and complex, and sometimes an a priori guess of the temperature is desirable. In this work we simulate the space and time dependent temperature distribution during FLA and compare it with experimental results, e.g. with observable phase changes during the crystallization of amorphous Si layers on insulator for thin film transistor applications. In detail, we will address the following items: (i) the influence of multiple reflections within the layer system as well as between sample and chamber walls, (ii) the influence of lateral and transversal temperature gradients, and (iii) the edge overheating problem. Simulations were performed with the help of both in-house and commercial software tools.
Keywords: flash lamp annealing, temperature distribution, crystallization, amorphous silicon
  • Lecture (Conference)
    European Material Research Society, Fall Meeting 2015, 15.-18.09.2015, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-22490
Publ.-Id: 22490


ESTRO consensus guideline on target volume delineation for elective radiation therapy of early stage breast cancer.

Offersen, B. V.; Boersma, L. J.; Kirkove, C.; Hol, S.; Aznar, M. C.; Biete Sola, A.; Kirova, Y. M.; Pignol, J. P.; Remouchamps, V.; Verhoeven, K.; Weltens, C.; Arenas, M.; Gabrys, D.; Kopek, N.; Krause, M.; Lundstedt, D.; Marinko, T.; Montero, A.; Yarnold, J.; Poortmans, P.
BACKGROUND AND PURPOSE:

Delineation of clinical target volumes (CTVs) is a weak link in radiation therapy (RT), and large inter-observer variation is seen in breast cancer patients. Several guidelines have been proposed, but most result in larger CTVs than based on conventional simulator-based RT. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.
MATERIAL AND METHODS:

During ESTRO teaching courses on breast cancer, teachers sought consensus on delineation of CTV through dialogue based on cases. One teacher delineated CTV on CT scans of 2 patients, followed by discussion and adaptation of the delineation. The consensus established between teachers was sent to other teams working in the same field, both locally and on a national level, for their input. This was followed by developing a broad consensus based on discussions.
RESULTS:

Borders of the CTV encompassing a 5mm margin around the large veins, running through the regional lymph node levels were agreed, and for the breast/thoracic wall other vessels were pointed out to guide delineation, with comments on margins for patients with advanced breast cancer.
CONCLUSION:

The ESTRO consensus on CTV for elective RT of breast cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency.

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Permalink: https://www.hzdr.de/publications/Publ-22489
Publ.-Id: 22489


Package Labelling with Printed Metal-Particle Suspensions using Millisecond Thermal Processing

Wiesenhütter, K.; Schumann, T.; Zichner, R.; Gebel, T.; Wiesenhütter, U.; Richter, H. U.; Skorupa, W.
The need for novel, flexible and low-cost electronic products with functionality far beyond that offered by conventional size-restricted and rigid semiconductor devices requires a rapid development of advanced material and deposition technology concepts. One of the most promising pathways to realize this ambitious goal is printed flexible electronics (PFE). Recently, printing has successfully demonstrated its potential for manufacture of advanced low-cost electronic products such as flexible displays, thin-film solar cells, large-area sensors etc. Importantly, by using bendable, inexpensive media (e.g.: paper-like substrates, polymer films) and high-throughput roll-to-roll (R2R) processing, a significant reduction of the overall costs associated with electronic device fabrication has been achieved.
Here, we report on a successful application of millisecond thermal processing by flash lamp annealing (FLA) as a highly-attractive technique for the functionalization of copper paste screen printed on low-thermal budget paper-like media for package labelling. The effect of the FLA parameters (i.e. pulse duration and energy density), on the substrate behavior as well as on the microstructure and electrical response of the as-flashed films was studied. A significant drop of the sheet resistance of the FL-treated layers as compared to the as-printed layers was observed. As ms-FLA permits selective, near-surface heating, a damage of the sensitive substrates was avoided. The microstructure of the copper paste before and after FLA was also investigated. Being highly-efficient, “non-destructive, and compatible with R2R processing, FLA offers the realization of advanced PFE products.
Keywords: package labeling, flash lamp annealing, millisecond thermal processeing, metal-particle suspension
  • Lecture (Conference)
    Paper electronics: a new challenge for materials a new opportunity for devices II, Symposium BB at the E-MRS Spring Meeting, 11.-15.05.2015, Lille, France

Permalink: https://www.hzdr.de/publications/Publ-22488
Publ.-Id: 22488


Aldehyde Dehydrogenase Is Regulated by β-Catenin/TCF and Promotes Radioresistance in Prostate Cancer Progenitor Cells.

Cojoc, M.; Peitzsch, C.; Kurth, I.; Trautmann, F.; Kunz-Schughart, L. A.; Telegeev, G. D.; Stakhovsky, E. A.; Walker, J. R.; Simin, K.; Lyle, S.; Fuessel, S.; Erdmann, K.; Wirth, M. P.; Krause, M.; Baumann, M.; Dubrovska, A.
Radiotherapy is a curative treatment option in prostate cancer. Nevertheless, patients with high-risk prostate cancer are prone to relapse. Identification of the predictive biomarkers and molecular mechanisms of radioresistance bears promise to improve cancer therapies. In this study, we show that aldehyde dehydrogenase (ALDH) activity is indicative of radioresistant prostate progenitor cells with an enhanced DNA repair capacity and activation of epithelial-mesenchymal transition (EMT). Gene expression profiling of prostate cancer cells, their radioresistant derivatives, ALDH(+) and ALDH(-) cell populations revealed the mechanisms, which link tumor progenitors to radioresistance, including activation of the WNT/β-catenin signaling pathway. We found that expression of the ALDH1A1 gene is regulated by the WNT signaling pathway and co-occurs with expression of β-catenin in prostate tumor specimens. Inhibition of the WNT pathway led to a decrease in ALDH(+) tumor progenitor population and to radiosensitization of cancer cells. Taken together, our results indicate that ALDH(+) cells contribute to tumor radioresistance and their molecular targeting may enhance the effectiveness of radiotherapy.

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Permalink: https://www.hzdr.de/publications/Publ-22487
Publ.-Id: 22487


Thermal processing within milliseconds: semiconductors and beyond

Skorupa, W.
In this talk I will review the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/. An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/. We prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).
Keywords: flash lamp annealing, subsecond thermal processing, ion implantation, semiconductors, doping, nanowires
  • Invited lecture (Conferences)
    Gettering and Defect Engineering in Semiconductor Technology 2015 — 30 Years of GADEST, 20.-25.09.2015, Erlangen, Germany

Permalink: https://www.hzdr.de/publications/Publ-22485
Publ.-Id: 22485


Subsecond thermal processing for nanostructured semiconductors

Skorupa, W.
This talk reviews the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/.
An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/. We prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters after ion implantation and FLA /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).
Keywords: flash lamp annealing, subsecond thermal processing, ion implantation, semiconductors, doping, nanowires
  • Invited lecture (Conferences)
    28th International Conference on Defects in Semiconductors (ICDS 2015), 27.-31.07.2015, Aalto, Finland

Permalink: https://www.hzdr.de/publications/Publ-22484
Publ.-Id: 22484


Nanotechnologie für die Korrosionsunterdrückung an Metall-Legierungen

Skorupa, W.
Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns mit der Anwendung der Nanotechnologie für den Korrosionsschutz von Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung) beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.
Keywords: Corrosion, plasma immersion ion implantation, lead-tin alloy, copper-zinc-alloy, nanotechnology
  • Lecture (Conference)
    37. Treffen der Nutzergruppe Heißprozesse und RTP, 25.03.2015, Erlangen, Germany

Permalink: https://www.hzdr.de/publications/Publ-22483
Publ.-Id: 22483


Plasmaimmersions-Implantation gegen Korrosion an Metall-Legierungen

Skorupa, W.
Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns mit der Anwendung der Nanotechnologie für den Korrosionsschutz von Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung) beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.
Keywords: Corrosion, plasma immersion ion implantation, lead-tin alloy, copper-zinc-alloy
  • Lecture (Conference)
    53. Treffen der Nutzergruppe Ionenimplantation, 26.03.2015, Erlangen, Germany

Permalink: https://www.hzdr.de/publications/Publ-22482
Publ.-Id: 22482


Adapting Scott and Bruce's General Decision-Making Style Inventory to Patient Decision Making in Provider Choice.

Fischer, S.; Soyez, K.; Gurtner, S.
OBJECTIVE:

Research testing the concept of decision-making styles in specific contexts such as health care-related choices is missing. Therefore, we examine the contextuality of Scott and Bruce's (1995) General Decision-Making Style Inventory with respect to patient choice situations.
METHODS:

Scott and Bruce's scale was adapted for use as a patient decision-making style inventory. In total, 388 German patients who underwent elective joint surgery responded to a questionnaire about their provider choice. Confirmatory factor analyses within 2 independent samples assessed factorial structure, reliability, and validity of the scale.
RESULTS:

The final 4-dimensional, 13-item patient decision-making style inventory showed satisfactory psychometric properties. Data analyses supported reliability and construct validity. Besides the intuitive, dependent, and avoidant style, a new subdimension, called "comparative" decision-making style, emerged that originated from the rational dimension of the general model.
CONCLUSIONS:

This research provides evidence for the contextuality of decision-making style to specific choice situations. Using a limited set of indicators, this report proposes the patient decision-making style inventory as valid and feasible tool to assess patients' decision propensities.
Keywords: decision-making style; patient choice; scale development and adaption

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Permalink: https://www.hzdr.de/publications/Publ-22481
Publ.-Id: 22481


Nanotechnologie mittels Dünnschichtabscheidung und Plasmaimmersions-Implantation für die Korrosionsunterdrückung an Metall-Orgelpfeifen

Skorupa, W.; Pelic, B.; Eule, A.-C.; Werner, H.
Die klassische Orgel ist die wahrscheinlich komplexeste Errungenschaft des Abendlandes, da ihre Herstellung und Nutzung neben handwerklich-produktionstechnischen und wissenschaftlichen auch künstlerisch-ästhetische und religiöse Komponenten aufweist. Trotzdem unterliegt auch sie dem allbekannten Verfallsmechanismus der menschlichen Schöpfungen, in diesem Fall infolge Korrosion, die sich vor allem bei den metallischen Werkstoffen bemerkbar macht. Dies sind hauptsächlich Blei-Zinn-Legierungen und Messing (Cu-Zn-Legierung). Während die Bleikorrosion infolge von organischen Säuredämpfen (Essigsäure, Ameisensäure) schon Jahrhunderte bekannt ist, wurde die Korrosion von Messing im Orgelbau eher marginal berichtet. Eine der wesentlichen Ursachen für die Säuredämpfe liegt in der Verwendung von Holzkonstruktionen im Orgelbau, wobei vor allem Eichenholz aufgrund seines Essigsäuregehaltes kritisch ist.
Im Rahmen eines vom Freistaat Sachsen über die Sächsische Aufbaubank geförderten Projektes haben wir uns, nach unserem Wissen weltweit erstmals, mit der Anwendung der Nanotechnologie für den Korrosionsschutz der genannten metallischen Materialien beschäftigt. Es wurde Dünnschichtabscheidung mittels gepulstem Laser bzw. Magnetronsputtern in Kombination zur Plasmaimmersions-Implantation verwendet. Problematisch ist dabei auch, dass beide Legierungen wenig vakuumverträglich sind. Es werden Ergebnisse von Laborstudien und Feldexperimenten in Kirchen für die beiden o.g. Legierungen berichtet, die effiziente Korrosionshemmung mit Dünnschichten im Dickenbereich <50 nm demonstrieren.
Keywords: corrosion, plasma immersion ion implantation, lead-tin alloy, brass, Cu-Zn alloy
  • Lecture (Conference)
    Workshop "Oberflächentechnologie mit Plasma- und Ionenstrahlprozessen", 10.-12.03.2015, Mühlleithen, Vogtland, Sachsen, Germany

Permalink: https://www.hzdr.de/publications/Publ-22480
Publ.-Id: 22480


Subsecond thermal processing for nanomaterials and beyond

Skorupa, W.
This talk reviews the advances that subsecond thermal processing in the millisecond range using xenon-filled flash lamps (FLA) brings to the processing of advanced semiconductor materials, thus enabling the fabrication of novel electronic structures and materials. It will be demonstrated how such developments can translate into important practical applications via doping and/or defect engineering. A recent state-of-the-art is published in Ref./1/.
An important issue of our present work is the liquid phase processing in the millisecond range at the surface of solid substrates. A recent example is the controlled formation of III-V nanocrystals (InAs, GaAs) in silicon nanowires after ion beam synthesis /2/, see the contribution of S.Prucnal at this workshop. Further, we prepared coarse grained dendritic crystal structures in thin silicon films on silicon dioxide to show that the addition of carbon prevents the agglomeration of the molten silicon films and largely influences the crystallisation process /3/. We could demonstrate that germanium and silicon exhibit superconductivity at ambient pressure and temperatures in the range of 1-2 K by avoiding Ga clusters after ion implantation and FLA /4/. Regarding photovoltaic applications, we dealt with the ion beam doping and thermal processing of PV silicon demonstrating a distinct improvement of the minority carrier diffusion length compared to rapid thermal processing and furnace treatments /5/. Moreover, we engineered the hydrogen content in photovoltaic silicon in correlation to the phosphorus doping using plasma immersion ion implantation and FLA /6/. Also, we demonstrated FLA driven phosphorus in-diffusion from a surface source /7/.

/1/ W. Skorupa and H. Schmidt: “Subsecond annealing of advanced materials”, Springer Series in Materials Science 192 (2014), ISBN 978-3-319-03131-6.
/2/ S.Prucnal,…,W.Skorupa et al.: “III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”, Nano Research 7, 1769 (2014); (see also Nano Lett. 11, 2814 (2011)).
/3/ M.Voelskow,…,W.Skorupa et al.: “Formation of dendritic crystal structures in thin silicon films on silicon dioxide by carbon ion implantation and high intensity large area flash lamp irradiation”, J. Cryst. Growth, 388, 70 (2014)
/4/ V.Heera,…,W.Skorupa et al.: “Depth-resolved transport measurements and atom-probe tomography of heterogeneous, superconducting Ge:Ga films”, Supercond.Sc.&Technol. 27, 055025 (2014).
/5/ S.Prucnal,…,W.Skorupa et al.: “Millisecond annealing for advanced doping of dirty-silicon solar cells”, J. Appl. Phys. 111, 123104 (2012).
/6/ F.L. Bregolin,…,W.Skorupa et al.:“Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates”, J. Appl. Phys. 115, 064505 (2014).
/7/ H.B. Normann,…,W.Skorupa et al.: “Phosphorus in-diffusion from a surface source by millisecond flash lamp annealing for shallow emitter solar cells”, Appl.Phys.Lett. 102, 132108 (2014).
Keywords: flash lamp annealing, thermal processing, ion implantation, semiconductors
  • Invited lecture (Conferences)
    NATO Advanced Research Workshop: "Functional Nanomaterials and Devices for Electronics, Sensors, Energy Harvesting", 13.-16.04.2015, Lviv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-22479
Publ.-Id: 22479


Comparative study of defect evolution in carbon implanted strained SiGe and SiSn layers

Gaiduk, P. I.; Hansen, J. L.; Larsen, A. N.; Skorupa, W.
By combining secondary ion-mass spectrometry, transmission-electron microscopy (TEM) and Rutherford-backscattering spectrometry we show that the redistribution of implanted carbon atoms around epitaxially strained Si/SiGe layers results in their accumulation on the Si side and depletion on the SiGe side. On the contrary, uphill diffusion of carbon into SiSn layers takes place in the case of Si/SiSn structures. The TEM study demonstrates formation of dislocation loops, stacking faults and interstitial clusters in the Si/SiGe layers, but elimination of interstitial dislocation loops and suppression of tin precipitates in the Si/SiSn layers. We deduced different evolution of dislocation loops and a precipitate is due to dopant-defect complexes. The complex formation is enhanced by separation of implanted point defects in strain-fields of Si/SiSn and Si/SiGe layers.
Keywords: epitaxially strained Si/SiGe layers, carbon, diffusion, ion implantation

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Permalink: https://www.hzdr.de/publications/Publ-22478
Publ.-Id: 22478


The precession dynamo experiment at HZDR

Giesecke, A.; Gundrum, T.; Herault, J.; Stefani, F.; Gerbeth, G.
In a next generation dynamo experiment currently under development at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) a fluid flow of liquid sodium, solely driven by precession, will be considered as a possible source for magnetic field generation. The experiment is mainly motivated by alternative concepts for astrophysical dynamos that are based on mechanical flow driving. For example, it has long been discussed whether precession may be a complementary power source for the geodynamo (Malkus, Science 1968) or for the ancient lunar dynamo due to the Earth-driven precession of the lunar spin axis (Dwyer, Nature 2011).

We will present the current state of development of the dynamo experiment together with results from non-linear hydrodynamic simulations with moderate precessional forcing. Our simulations reveal a non-axisymmetric forced mode with an amplitude of up to one fourth of the rotation velocity of the cylindrical container confirming that precession provides a rather efficient flow driving mechanism even at moderate precession rates.

More relevant for dynamo action might be free Kelvin modes (the natural flow eigenmodes in a rotating cylinder) with higher azimuthal wave number. These modes may become relevant when constituting a triadic resonance with the fundamental forced mode, i.e., when the height of the container matches their axial wave lengths. We find triadic resonances at aspect ratios close to those predicted by the linear theory except around the primary resonance of the forced mode. In that regime we still identify free Kelvin modes propagating in retrograde direction but none of them can be assigned to a triade.

Our results will enter into the development of flow models that will be used in kinematic simulations of the electromagnetic induction equation in order to determine whether a precession driven flow will be capable to drive a dynamo at all and to limit the parameter space within which the occurrence of dynamo action is most promising.
Keywords: Dynamo Dresdyn Precession
  • Poster
    AGU Fall Meeting 2015, 13.-18.12.2015, San Francisco, USA
  • Open Access Logo Contribution to proceedings
    AGU Fall Meeting 2015, 13.-18.12.2015, San Francisco, USA

Permalink: https://www.hzdr.de/publications/Publ-22477
Publ.-Id: 22477


Targeting of the EGFR/β1 integrin connecting proteins PINCH1 and Nck2 radiosensitizes three-dimensional SCC cell cultures.

Rossow, L.; Eke, I.; Dickreuter, E.; Cordes, N.
Epidermal growth factor receptor (EGFR) signaling plays an important role in tumor cell resistance to therapy. In addition to ligand binding, mutual and cooperative interactions of EGFR with integrin cell adhesion receptors critically influence proper downstream signaling through a number of bridging adapter proteins. In the present study, we analyzed the role of two of these adapter proteins, called PINCH1 and Nck2, for cellular radioresistance in combination with EGFR-targeting using the monoclonal antibody cetuximab. siRNA-mediated knockdown of PINCH1 or Nck2 resulted in enhanced radiosensitivity of 3D grown human squamous cell carcinoma cell lines FaDu (head and neck) and A431 (epidermis) comparable with effects seen after cetuximab treatment. Combination of knockdown and cetuximab did not result in additive nor synergistic effects regarding clonogenic radiation survival. Modifications in MAPK, Akt and FAK phosphorylation occurred upon cetuximab treatment as well as PINCH1 or Nck2 depletion. We further found this tumor cell radiosensitization to be due to attenuated repair of DNA double strand breaks and altered Rad50 and Nbs1 expression but without changes in other DNA repair proteins such as ATM, DNA-PK and Mre11. Our data suggest that the adaptor proteins PINCH1 and Nck2 critically contribute to cellular radioresistance and proper EGFR signaling in 3D lrECM grown human squamous cell carcinoma cells. Further investigations are warranted to identify the intracellular signaling network controlled by EGFR, PINCH1 and Nck2.

Permalink: https://www.hzdr.de/publications/Publ-22476
Publ.-Id: 22476


Ion beam technology

Fassbender, J.ORC
Overview over ion beam technology at HZDR
  • Invited lecture (Conferences)
    High resolution diagnostics and ion beam technology, 01.-02.10.2015, Bratislava, Slovakei

Permalink: https://www.hzdr.de/publications/Publ-22474
Publ.-Id: 22474


High-field magnetic behavior and forced-ferromagnetic state in an ErFe11TiH single crystal

Kostyuchenko, N. V.; Zvezdin, A. K.; Tereshina, E. A.; Skourski, Y.; Doerr, M.; Drulis, H.; Pelevin, I. A.; Tereshina, I. S.
The crystal-field and exchange parameters are determined for the single-crystalline hydride ErFe11TiH compound by analyzing the experimental magnetization curves obtained in magnetic fields of up to 60 T. By using the calculated parameters we succeeded in modeling theoretical magnetization curves for ErFe11TiH up to 200 Т and to study in detail the transition from ferrimagnetic to a ferromagnetic state in the appliedmagnetic field.

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Permalink: https://www.hzdr.de/publications/Publ-22473
Publ.-Id: 22473


Enhanced low-energy γ-decay probability - implications for r-process (n,γ) reaction rates

Larsen, A. C.; Guttormsen, M.; Bello-Garrotte, F. L.; Bernstein, L. A.; Bleuel, D. L.; Bracco, A.; Brown, B. A.; Camera, F.; Crespo-Campo, L.; Frauendorf, S.; Goldblum, B. L.; Goriely, S.; Görgen, A.; Hadynska-Klek, K.; Hagen, T. W.; Harissopulos, S.; Kheswa, B. V.; Klintefjord, M.; Leoni, S.; Liddick, S. N.; Moretto, L. G.; Naqvi, F.; Perdikakis, G.; Renstrøm, T.; Rogers, A. M.; Rose, S. J.; Sahin, E.; Schwengner, R.; Siem, S.; Simon, A.; Spyrou, A.; Tveten, G. M.; Voinov, A.; Wiedeking, M.; Utsunomiya, H.
An unexpected enhancement in the average, reduced γ-decay strength at very low -transition energies has been observed in in f p-shell nuclei as well as in the Mo region. Very recently, it has showed up in 138 La, which is, so far, the heaviest nucleus to display this feature. In this work, we present an experimental and theoretical overview of the low-energy enhancement. In particular, experimental evidence for the dipole nature of the enhancement, and shell-model calculations indicating strong, low-energy M 1 transitions are shown. Possible implications of this low-energy enhancement on astrophysical (n,γ ) reaction rates of relevance for the r-process nucleosynthesis are discussed.
Keywords: Nuclear structure, nuclear reactions, gamma strength function, neutron capture, reaction rates.
  • Open Access Logo Contribution to proceedings
    14th International Conference on Nuclear Reaction Mechanisms, 15.-19.06.2015, Varenna, Italien
    Proceedings of the 14th International Conference on Nuclear Reaction Mechanisms, Genf: CERN-Proceedings, ISBN 978-92-9083-418-2, 261-266

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Permalink: https://www.hzdr.de/publications/Publ-22472
Publ.-Id: 22472


RF performance results of the 2nd ELBE SRF gun

Arnold, A.; Freitag, M.; Lu, P.; Murcek, P.; Teichert, J.; Vennekate, H.; Xiang, R.; Kneisel, P.; Ciovati, G.; Turlington, L.
An improved SRF gun (ELBE SRF gun II) has been installed and commissioned at HZDR. This new gun replaced the first SRF gun of the ELBE accelerator which had been in operation since 2007. The new gun has an improved 3.5-cell niobium cavity those SRF performances have been studied first with a copper cathode. After the replacement by our standard Cs2Tecathode we observed a tremendous degradation of the cavity gradient paired with an increase of field emission. In this contribution we will report on our in-situ investigations to find the origin and the reason for the particle contamination that happened during the first cathode transfer.
Keywords: SRF gun, photo electron source, injector, ELBE, superconducting RF
  • Poster
    7th International Conference on RF Superconductivity, SRF 2015, 13.-18.09.2015, Whistler, British Columbia, Canada
  • Open Access Logo Contribution to proceedings
    7th International Conference on RF Superconductivity, SRF 2015, 13.-18.09.2015, Whistler, British Columbia, Canada
    Proceedings of the 7th International Conference on RF Superconductivity: Joint Accelerator Conferences Website (JACoW)

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Permalink: https://www.hzdr.de/publications/Publ-22470
Publ.-Id: 22470


Imaging of tumour hypoxia and metabolism in patients with head and neck squamous cell carcinoma.

Zegers, C. M.; van Elmpt, W.; Hoebers, F. J.; Troost, E. G.; Öllers, M. C.; Mottaghy, F. M.; Lambin, P.
BACKGROUND:

Tumour hypoxia and a high tumour metabolism increase radioresistance in patients with head and neck squamous cell carcinoma (HNSCC). The aim of this study was to evaluate the correlation between hypoxia ([18F]HX4 PET) and glucose metabolism ([18F]FDG PET) molecular imaging.
MATERIAL AND METHODS:

[18F]HX4 and [18F]FDG PET/CT images of 20 HNSCC patients were acquired prior to (chemo)radiotherapy, in an immobilisation mask, with a median time interval of seven days (NCT01347281). Gross tumour volumes of the primary lesions (GTVprim) and pathological lymph nodes (GTVln) were included in the analysis. [18F]FDG PET/CT images were rigidly registered to the [18F]HX4 PET/CT images. The maximum and mean standardised uptake values (SUVmax, SUVmean) within both GTVs were determined. In addition, the overlap was compared between the [18F]HX4 high volume ([18F]HX4 HV) with a tumour-to-muscle ratio > 1.4 and the [18F]FDG high volume ([18F]FDG HV) with an SUV > 50% of the SUVmax. We report the mean± standard deviation.
RESULTS:

PET/CT scans including 20 GTVprim and 12 GTVlnwere analysed. There was a significant correlation between several [18F]FDG and [18F]HX4 parameters, the most pronounced being the correlation between [18F]FDG HV and [18F]HX4 HV (R = 0.93, p < 0.001). The fraction of the GTVprim with a high HX4 uptake (9 ± 10%) was on average smaller than the FDG high fraction (51 ± 26%; p < 0.001). In 65% (13/20) of the patients, the GTVprim was hypoxic. In four of these patients the [18F]HX4 HV was located within the [18F]FDG HV, whereas for the remaining nine GTVprim a partial mismatch was observed. In these nine tumours 25 ± 21% (range 5-64%) of the HX4 HV was located outside the FDG HV.
CONCLUSIONS:

There is a correlation between [18F]HX4 and [18F]FDG uptake parameters on a global tumour level. In the majority of lesions a partial mismatch between the [18F]HX4 and [18F]FDG high uptake volumes was observed, therefore [18F]FDG PET imaging cannot be used as a surrogate for hypoxia. [18F]HX4 PET provides complementary information to [18F]FDG PET imaging.

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Permalink: https://www.hzdr.de/publications/Publ-22469
Publ.-Id: 22469


Weekly kilovoltage cone-beam computed tomography for detection of dose discrepancies during (chemo)radiotherapy for head and neck cancer.

Hermans, B. C.; Persoon, L. C.; Podesta, M.; Hoebers, F. J.; Verhaegen, F.; Troost, E. G.
BACKGROUND:

Use of highly conformal radiotherapy in patients with head and neck carcinoma may lead to under-/overdosage of gross target volume (GTV) and organs at risk (OAR) due to changes in patients' anatomy. A method to achieve more effective radiation treatment combined with less toxicity is dose-guided radiotherapy (DGRT). The aim of this study was to evaluate discrepancies between planned and actually delivered radiation dose in head and neck patients and to identify predictive factors.
METHODS:

In this retrospective analysis, 20 patients with cT2-4 N0-3 M0 carcinoma originating from oropharynx, oral cavity, larynx and hypopharynx (Cohort 1), and seven patients with cT1-4 N0-3 M0 nasopharyngeal carcinoma (Cohort 2) treated with primary (chemo)radiotherapy and undergoing weekly kV-CBCT scans were included. Radiation dose was recalculated on 184 kV-CBCT images, which was quantified by D95% (GTV), Dmean (parotid and submandibular glands) and D2% (spinal cord). Predictive factors investigated for changes in these dose metrics were: gender, age, cT/N-stage, tumor grade, HPV-status, systemic therapy, body mass index at start of treatment, weight loss and volume change over the duration of the radiotherapy.
RESULTS:

There was no significant difference between the planned and delivered dose for GTV and OARs of Week 1 to subsequent weeks for Cohort 1. In Cohort 2, actually delivered Dmean to parotid glands was significant higher than planned dose (1.1 Gy, p = 0.002). No clinically relevant correlations between dose changes and predictive factors were found.
CONCLUSION:

Weekly dose calculations do not seem to improve dose delivery for patients with tumors of the oral cavity, oropharynx, larynx and hypopharynx. In patients with nasopharyngeal carcinoma, however, mid-treatment imaging may facilitate DGRT.

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Permalink: https://www.hzdr.de/publications/Publ-22468
Publ.-Id: 22468


Impact of waiting time after surgery and overall time of postoperative radiochemotherapy on treatment outcome in glioblastoma multiforme.

Seidlitz, A.; Siepmann, T.; Löck, S.; Juratli, T.; Baumann, M.; Krause, M.
BACKGROUND:

A time factor of radiooncological treatment has been demonstrated for several tumours, most prominently for head and neck squamous cell carcinoma and lung cancer. In glioblastoma multiforme studies of the impact of postoperative waiting times before initiation of radio- or radiochemotherapy were inconclusive. Moreover analysis of the impact of overall treatment time of radiochemotherapy as well as overall duration of local treatment from surgery to the end of radiochemotherapy is lacking to date.
METHODS:

In this retrospective cohort study, we included 369 consecutive patients treated at our institution between 2001 and 2014. Inclusion criteria were histologically proven glioblastoma multiforme, age ≥ 18 years, ECOG performance status 0-2 before radiotherapy, radiotherapy or radiochemotherapy with 33 × 1.8 Gy to 59.4 Gy or with 30 × 2.0 Gy to 60 Gy. The impact of postoperative waiting time, radiation treatment time and overall duration of local treatment from surgery to the end of radiotherapy on overall (OS) and progression-free (PFS) survival were evaluated under consideration of known prognostic factors by univariate Log-rank tests and multivariate Cox-regression analysis.
RESULTS:

The majority of patients had received simultaneous and further adjuvant chemotherapy, mainly with temozolomide. Median survival time and 2-year OS were 18.0 months and 38.9% after radiochemotherapy compared to 12.7 months and 12.6% after radiotherapy alone. Median progression-free survival time was 7.5 months and PFS at 2 years was 14.3% compared to 6.0 months and 3.3%, respectively. Significant prognostic factors in multivariate analysis were age, resection status and application of simultaneous chemotherapy. No effect of the interval between surgery and adjuvant radiotherapy (median 27, range 11-112 days), radiation treatment time (median 45, range 40-71 days) and of overall time from surgery until the end of radiotherapy (median 54, range 71-154 days) on overall and progression-free survival was evident.
CONCLUSION:

Our data do not indicate a relevant time factor in the treatment of glioblastoma multiforme in a large contemporary single-centre cohort. Although this study was limited by its retrospective nature, its results indicate that short delays of postoperative radiochemotherapy, e.g. for screening of a patient for a clinical trial, may be uncritical.

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Publ.-Id: 22467


Development of the first pulse powered radiotherapy gantry system for a novel compact laser driven ion beam therapy

Masood, U.; Baumann, M.; Bussmann, M.; Cowan, T. E.; Enghardt, W.; Herrmannsdoerfer, T.; Hofmann, K. M.; Karsch, L.; Kroll, F.; Schramm, U.; Schürer, M.; Wilkens, J. J.; Pawelke, J.
Purpose/Objective:
Ion beams due to superior dose profile over photons and electrons may provide higher doseconformity and healthy tissue sparing. But due to high costs and huge size ion beam therapy is limited to a few centers only. A novel ion acceleration process via ultra-intense lasermatter interaction, promises size and cost reduction. However, laser-driven beams are characterized by intense particle bunches with peak dose rates exceeding conventional values by several orders of magnitude, low repetition rate, broad energy spread and large divergence, thus are diverse from conventional beams. This requires new solutions for developing Laser-based Ion Beam Therapy (LIBT) for clinical application. The presented work is a result of an ongoing joint translational research project of several institutions aiming to establish LIBT with protons and shows the status in five main challenges.

Materials and Methods:
I) Laser-based technology has been established, with protons (upto 20 MeV) via 150 TW laser system, for systematic radiobiological studies with human cell-lines and small animals with fixed beamline.
II) For translation towards patient irradiation, increase of proton energy from 20 to 230 MeV by increasing the laser power from 150 TW to ~1 PW is required and in progress.
III) Furthermore, a compact ion beam gantry system is designed based on pulsed magnets (PM), with integrated laser-particle acceleration chamber, novel beam capturing and energy selection system. A new pulsed scanning system for wide beams with broad energies is designed for irradiations with clinical accuracy.
IV) The light-weight iron-less high-field PMs are being developed for gantry realization. These are non-trivial and extremely challenging to design.
V) A new 3D TPS has been developed for new dose delivery and treatment planning strategies for LIBT.

Results:
No overall difference in the radiobiological effectiveness between laser-driven and conventional beams was detected to date. Therefore, a comparison of dose plans by treatment planning system is possible to evaluate the features of LIBT. The evaluation of treatment plans shows laser driven broad energetic beams are feasible for clinical application. Our double-achromatic 360° isocentric pulsed gantry design is ~2.5x smaller than conventional gantries (see fig.) and is capable of disperssionless scanning of high acceptance beams through 20x20 cm2 field size. For the realization, PMs have been designed and developed. A pulsed solenoid, for particle capturing and focusing, has been successfully tested at laser-driven beams. A novel 10 T compact pulsed 45° sector magnet has been developed and tested. Also, a pulsed high acceptance quadrupole with 250 T/m gradient is being developed.

Conclusions:
LIBT is a promising compact alternative and could change IBT, yet requires substantial development towards clinical application. Supported by German BMBF, no. 03Z1N511 & DFG cluster of excellence MAP.

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Publ.-Id: 22466


Multiphoton-induced luminescence and its domain contrast in Mg-doped LiNbO3 and LiTaO3

Reichenbach, P.; Kämpfe, T.; Haußmann, A.; Steudtner, R.; Woike, T.; Eng, L. M.
We investigate the luminescence in a wide bandgap oxide, Mg-doped LiNbO3 and LiTaO3 , with both spectral and temporal resolution, enhancing the insight into the relaxation properties relevant in these materials.
  • Lecture (Conference)
    DPG Frühjahrstagung, 15.-20.03.2015, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22465
Publ.-Id: 22465


Superparamagnetic behavior of Fe doped InAs prepared by ion implantation and pulsed laser annealing

Yuan, Y.; Sawicki, M.; Cai, H.; Helm, M.; Zhou, S.
Dilute magnetic semiconductors (DMSs) attracted great interests in the last several decades because of their potential for spintronic device [1]. III-V compounds especially GaAs based DMS has recently emerged as the most popular material for this new technology. However, that the low mobility of holes in p-type DMS limits the potential application in semiconductor spintronic devices. Therefore, the searching for n-type DMS is of interest.

The doping of Fe in InAs is attracting research attentions due to the possibility to fabricate n-type diluted magnetic semiconductors [2, 3]. However, the low solubility of Fe in InAs is the most difficulty to achieve InFeAs DMS. In this work, we obtain Fe doped InAs layers by ion implantation and pulsed laser annealing. This approach has shown success for preparing other III-V based DMSs [4, 5]. The formed InFeAs layers are proved to be epitaxial-like on InAs substrates. The prepared InFeAs layers reveal similar magnetic properties independent of their conductivity types. While the samples are lacking of charactersistics of DMS, they appear to be superparamagnetic behavior, revealing such as time-dependent magnetiszation measurements reveal aging and memory effects.


1. T. Dietl et al., Science 287, 1019-1022 (2000)
2. M. Kobayashi et al., Appl. Phys. Lett., 105, 032403(2014)
3. P. Nam Hai et al., Appl. Phys. Lett., 101, 182403 (2012)
4. D. Bürger et al., Phys. Rev. B, 81, 115202 (2010)
5. M. Khalid et al., Phys. Rev. B, 89, 121301(R) (2014)
  • Lecture (Conference)
    EMRS 2015 Fall meeting, 15.-18.09.2015, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-22464
Publ.-Id: 22464


Electronic Transport through Au-contacted PEEB

Kelling, J.; Sendler, T.; Erbe, A.; Gemming, S.
Abstract Transport through the organic molecule 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene (PEEB) has been investigated using Density functional Theory (DFT) and the Non-Equilibrium Green's Function (NEGF) approach in order to explain results of experiments employing the mechanically controlled break junction (MCBJ) technique. The molecule was studied with various terminal groups (NH2, SH and CN) which lead to different conductance values when attached to Gold electrodes. The effect of different contact geometries was studied in simulations, allowing predictions on the most likely contact geometries occurring in experiments.
  • Poster
    NanoNet Workshop, 30.09.-02.10.2015, Rathen, Sächsische Schweiz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22463
Publ.-Id: 22463


Electronic Transport through Au-contacted, Thiol-terminated PEEB

Kelling, J.; Sendler, T.; Erbe, A.; Gemming, S.
Transport through the organic molecule 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene (PEEB) with Thiol (SH) terminal groups, contacted by Gold electrodes, has been investigated using Density functional Theory (DFT) and the Non-Equilibrium Green’s Function (NEGF) method. The results confirm the existence of a single-atom contact configuration with unusually high conductance for organic molecules of >0.1G0.
  • Lecture (others)
    NanoNet Workshop, 30.09.-02.10.2015, Rathen, Sächsische Schweiz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22462
Publ.-Id: 22462


Accounting for Spectral History Effects with improved microscopic depletion in DYN3D code

Bilodid, Y.; Kotlyar, D.; Shwageraus, E.; Fridman, E.; Kliem, S.
Nodal diffusion codes such as DYN3D are used routinely for nuclear reactor simulations. These codes obtain homogenized few-group macroscopic reaction cross sections (XS) of coarse-mesh space elements (nodes) from XS-libraries, which are generated using lattice neutron transport codes. The libraries represent the dependence of homogenized XS on operational parameters such as fuel temperature, moderator density, moderator temperature, boron concentration and fuel burnup.

Typically, XS libraries are calculated using a branching procedure in which a 2D fuel assembly is first depleted to a certain burnup using core average operating conditions. Then, the branching calculations are performed at predetermined burnup points for all expected combinations of operating conditions. However, the local operating conditions (moderator density, fuel temperature, control rod presence etc.) in the core nodes may differ significantly from the core average conditions. Therefore, XS generation using a single assembly depletion calculation under core averaged conditions neglects the local variations of the spectrum history and may lead to errors in the XS. In order to account for the local spectrum history effects, a new XS correction method was recently developed and implemented in DYN3D. The method utilizes the local Pu-239 concentration as an indicator of spectral history. Pu-correction was verified in a wide range of spectral conditions. However, it is not able to reproduce fuel reactivity changes due to outage periods.

This paper presents a new hybrid method developed and implemented in DYN3D, which utilizes advantages of both, the micro-depletion correction and Pu-correction. The macroscopic XS are corrected using local concentrations of the most neutronically important nuclides, which are calculated by DYN3D using fast and accurate CRAM method. The isotopic microscopic cross sections and macroscopic transport and scattering XS are corrected applying Pu-correction methodology. General applicability of the proposed method is demonstrated on various fuel types and spectral condition, including BWR and PWR unit cells with UOX and MOX fuel.
Keywords: micro depletion, DYN3D, spectral history
  • Contribution to proceedings
    25th Symposium of AER on VVER Reactor Physics and Reactor Safety, 13.-16.10.2015, Balatongyörök, Hungary
    Proceedings of the 25th Symposium of AER on VVER Reactor Physics and Reactor Safety
  • Lecture (Conference)
    25th Symposium of AER on VVER Reactor Physics and Reactor Safety, 13.-16.10.2015, Balatongyörök, Hungary

Permalink: https://www.hzdr.de/publications/Publ-22461
Publ.-Id: 22461


Thermal annealing behavior of α-Al2O3 scintillation screens

Lederer, S.; Akhmadaliev, S.; Forck, P.; Gütlich, E.; Lieberwirth, A.; Ensinger, W.
Polycrystalline alumina samples (α-Al2O3, purity: 99.8%) were irradiated by 63Cu heavy ions (E = 0.5 MeV/u) at various fluences. After irradiation, absorption measurements were performed within the wavelength range from 200 to 1000 nm to evaluate color center evolution. Thermal annealing behavior of the created defects was investigated with respect to annealing temperature and duration. Complex color center formation processes depending on particle fluence and temperature could be observed. Calculated activation energies necessary for F- and F+-center migration are ∼0.3 eV for temperatures ranging from RT to ∼673 K.
Keywords: Alumina; Heavy-ion irradiation; Color center; Thermal annealing; Scintillation screens

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Publ.-Id: 22460


Bestimmung der Gasphasenverteilung in industriellen Kreiselpumpen unter Nutzung der Gammastrahlentomographie

Neumann, M.
Die vorliegende Arbeit beschäftigt sich mit der quantitativen Bestimmung von Gasphasenverteilungen in industriellen Kreiselpumpen unter Verwendung der hoch auflösenden Gammastrahlentomographie. Die Messgenauigkeit des Tomographiesystems wurde mit einem rotierenden, modularen Messphantom bestimmt, welches entwickelt wurde um verschiedene Gasgehalte und Strukturen nachzubilden. Mit definierten Konfigurationen dieses Phantoms wurde erstmals eine kombinierte Methode zur Aufnahme der Tomographiedaten durchgeführt und validiert. Die anschließenden Untersuchungen einer Kreiselpumpe bei verschiedenen eingespeisten Gasgehalten zeigten einen Einfluss der Eintrittsbedingungen auf die Gasverteilung im Laufrad und somit auf das Betriebsverhalten.

This thesis presents the quantitative determination of gas-phase distributions in an industrial centrifugal pump using high-resolution gamma-ray computed tomography. Measurement accuracy was determined onto a sophisticated and rotated modular test mockup miming various gas fraction distributions and structures. Additionally, combined CT scanning mode was applied for the first time and validated using defined mockup configuration. Furthermore, investigations of the centrifugal pump operated with various gas fractions at the inlet showed a non-negligible influence of the inlet conditions onto the gas-phase distribution inside the impeller wheel and thus the operational behavior.
  • Diploma thesis
    Technische Universität Dresden, 2014
    Mentor: Schäfer, T., Bieberle, A., Hampel, U.
    90 Seiten

Permalink: https://www.hzdr.de/publications/Publ-22459
Publ.-Id: 22459


An experimental study on the gas entrainment in horizontally and vertically installed centrifugal pumps

Neumann, M.; Schäfer, T.; Bieberle, A.; Hampel, U.
In this work we have studied how gas accumulates in an industrial centrifugal pump under various steady-state two-phase flow conditions. Thereby we considered both horizontal and vertical pump installation positions. Phase fractions within the impeller region of the pump have been quantitatively disclosed using high-resolution gamma-ray computed tomography (HireCT) and applying time-averaged rotation-synchronized CT scanning technique. The study was made for inlet volumetric gas flow rates between 0 % and 5 %. To account for different inlet flow conditions, which are assumed to occur during unwanted gas entrainment by hollow vortices we produced disperse and swirling gas-liquid inlet flow. In this way, the influence of inlet flow boundary conditions on the pump performance as well as gas fraction distributions and gas holdup within the impeller wheel region could be successfully analysed and compared with respect to the impeller alignment. In addition, for the first time, thin gas films at the pressure side of the impeller wheel blades could be visualized in an industrial centrifugal pump.
Keywords: gamma-ray computed tomography, centrifugal pump, gas holdup, two-phase flow
  • Journal of Fluids Engineering - Transactions of the ASME 138(2016)9, 091301
    DOI: 10.1115/1.4033029

Permalink: https://www.hzdr.de/publications/Publ-22458
Publ.-Id: 22458


Exceptional points, spectral singularities, vector field singularities and discriminant varieties

Günther, U.
Many physically realistic problems can be described in terms of parameter-dependent eigenvalue problems of some non-Hermitian operators, as scattering problems or as dynamical flow problems. A common feature of such problems is the existence of degenerate configurations which can be associated to dynamical bifurcation behavior, spectral branch points or special types of singularities in the scattering matrix. Mathematically, such problems are related to non-diagonalizable spectral operator decompositions (the existence of non-trivial Jordan blocks), multiple eigenvalues and the coalescence of singularities in vector flow fields. In parameter spaces these configurations show up as so called discriminant varieties well known from algebraic geometry and singularity theory. In the talk, the structural interrelation of these effects is demonstrated and illustrated on concrete problems from PT quantum mechanics, optical lasing systems and the Bloch-sphere representation of simple time-dependent quantum mechanical problems.
Keywords: non-Hermitian operators, degenerate configurations, dynamical bifurcation behavior, spectral branch points, spectral singularities, Jordan blocks, multiple eigenvalues, singularity coalescence, discriminant varieties
  • Invited lecture (Conferences)
    Mathematics in Technical and Natural Sciences, 18.-24.09.2015, Koscielisko, Poland

Permalink: https://www.hzdr.de/publications/Publ-22456
Publ.-Id: 22456


Hamiltonian and dissipative second-order polynomial flows on spheres S^2

Günther, U.; Graefe, E.-M.; Korsch, H.-J.
The dynamics of nondissipative and dissipative autonomous Bose-Hubbard dimers is considered in second-order polynomial approximation as flow dynamics on the Bloch sphere. Special emphasis is laid on the stationary-point and singularity structure of the flows, related underlying algebraic stability features encoded in 10th-order homogeneous polynomials describing algebraic discriminant varieties over 3-dimensional projective parameter spaces. Reduced resolvent techniques, hidden Jordan block structures and relations to singularity theory provide further insights into the dynamics and possibly existing limit cycles.
Keywords: Bose-Hubbard model, dimer, autonomous dynamical system, Bloch Sphere, stationary points, discriminant varieties, reduced resolvent, Jordan blocks, limit cycles
  • Invited lecture (Conferences)
    Quantum (and Classical) Physics with Non-Hermitian Operators (PHHQP13), 12.-16.07.2015, Jerusalem, Israel

Permalink: https://www.hzdr.de/publications/Publ-22455
Publ.-Id: 22455


The In situ growth of nanostructures on surfaces (INS) endstation of the ESRF BM32 beamline: A combined UHV–CVD and MBE reactor for in situ X-ray scattering investigations of growing nanoparticles and semiconductor nanowires

Cantelli, V.; Geaymond, O.; Ulrich, O.; Zhou, T.; Blanc, N.; Renaud, G.
This paper presents the upgraded `In situ growth of Nanoscructures on Surfaces' (INS) endstation of the InterFace beamline IF-BM32 at the European Synchrotron Radiation Facility (ESRF). This instrument, originally designed to investigate the structure of clean surfaces/interfaces/thin-films by surface X-ray diffraction, has been further developed to investigate the formation and evolution of nanostructures by combining small- and wide-angle X-ray scattering methodologies, i.e. grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXD). It consists of a UHV chamber mounted on a z-axis type goniometer, equipped with residual gas analysis, reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) to complete the X-ray scattering investigations. The chamber has been developed so as up to eight sources of molecular beam epitaxy (MBE) can be simultaneously mounted to elaborate the nanostructures. A chemical vapor deposition (CVD) set-up has been added to expand the range of growing possibilities, in particular to investigate in situ the growth of semiconductor nanowires. This setup is presented in some detail, as well as the first in situ X-ray scattering measurements during the growth of silicon nanowires.
Keywords: In situ; nanowires; UHV–CVD; IF-BM32; GIXRD; GISAXS.

Permalink: https://www.hzdr.de/publications/Publ-22454
Publ.-Id: 22454


Application of ion beams to fabricate and tune ferromagnetic semiconductors

Zhou, S.
Combining semiconducting and ferromagnetic properties, ferromagnetic semiconductors have been under intensive investigation for more than two decades. Mn doped III-V compound semiconductors have been regarded as the prototype of ferromagnetic semiconductors from both experimental and theoretic investigations. The magnetic properties of III-V:Mn can be controlled by manipulating free carriers via electrical gating, as for controlling the electrical properties in conventional semiconductors. However, the preparation of ferromagnetic semiconductors presents a big challenge due to the low solubility of Mn in semiconductors. Ion implantation has been developed as a standard method for doping Si in microelectronic industry. In this talk, I will show how ion beams can be used in fabricating and understanding ferromagnetic semiconductors. First, ion implantation followed by pulsed laser melting (II-PLM) provides an alternative to the widely used low-temperature molecular beam epitaxy (LTMBE) approach [1-6]. Both ion implantation and pulsed-laser melting occur far enough from thermodynamic equilibrium conditions. Ion implantation introduces enough dopants and the subsequent laser pulse deposit energy in the near-surface region to drive a rapid liquid-phase epitaxial growth. Going beyond LT-MBE, II-PLM is successful to bring two new members, GaMnP and InMnP, into the family of III-V:Mn. Both GaMnP and InMnP films show the signature of ferromagnetic semiconductors and an insulating behavior. Second, we use helium ion to precisely compensate hole in ferromagnetic semiconductors while keeping the Mn concentration constant [7-9]. By this approach, one can tune the magnetic properties of ferromagnetic semiconductor as well as pattern a lateral structure. It also provides a route to understand how carrier-mediated ferromagnetism is influenced by localization.

[1] M. Scarpula, et al. Phys. Rev. Lett. 95, 207204 (2005).
[2] D. Bürger, S. Zhou, et al., Phys. Rev. B 81, 115202 (2010).
[3] S. Zhou, et al., Appl. Phys. Express 5, 093007 (2012).
[4] M. Khalid et al., Phys. Rev. B 89, 121301(R) (2014).
[5] Y. Yuan, et al, IEEE Trans. Magn. 50, 2401304 (2014).
[6] Y. Yuan, et al. J. Phys. D: Appl. Phys. in press (2015).
[7] Lin Li, et al., J. Phys. D: Appl. Phys. 44 099501 (2011).
[8] Lin Li, et al., Nucl. Instr. Meth. B, 269, 2469-2473 (2011).
[9] S. Zhou, et al. Phys. Rev. B, in revision (2015).
Keywords: Ferromagnetic semiconductors, Ion implantation
  • Invited lecture (Conferences)
    The 2015 E-MRS Fall Meeting, 14.-18.09.2015, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-22453
Publ.-Id: 22453


Tomography of the ionospheric electron density with geostatistical inversion

Minkwitz, D.; van den Boogaart, K. G.; Gerzen, T.; Hoque, M.
In relation to satellite applications like global navigation satellite systems (GNSS) and remote sensing, the electron density distribution of the ionosphere has significant influence on trans-ionospheric radio signal propagation. In this paper, we develop a novel ionospheric tomography approach providing the estimation of the electron density's spatial covariance and based on a best linear unbiased estimator of the 3-D electron density. Therefore a non-stationary and anisotropic covariance model is set up and its parameters are determined within a maximum-likelihood approach incorporating GNSS total electron content measurements and the NeQuick model as background. As a first assessment this 3-D simple kriging approach is applied to a part of Europe. We illustrate the estimated covariance model revealing the different correlation lengths in latitude and longitude direction and its non-stationarity. Furthermore, we show promising improvements of the reconstructed electron densities compared to the background model through the validation of the ionosondes Rome, Italy (RO041), and Dourbes, Belgium (DB049), with electron density profiles for 1 day. © Author(s) 2015.
Keywords: electron density; geostatistics; GNSS; inverse problem; ionosphere; kriging; remote sensing; tomography

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Publ.-Id: 22452


Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium-americium mixed oxides

Prieur, D.; Lebreton, F.; Martin, P. M.; Caisso, M.; Butzbach, R.; Somers, J.; Delahaye, T.
Uranium-americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U1(-x)Am(x)O(2 +/-delta) a samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U1-xAmxO2 +/-delta leads to the formation of similar fluorite solid solution indicating the presence of Am+III and U+V in equimolar proportions.
Keywords: EXFAS Uranium Americium nuclear fuel transmutation

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Publ.-Id: 22451


Ion induced magnetic patterning using chemical disordered induced ferromagnetism

Bali, R.; Wintz, S.; Meutzner, F.; Hübner, R.; Boucher, R.; Ünal, A. A.; Valencia, S.; Neudert, A.; Potzger, K.; Bauch, J.; Kronast, F.; Facsko, S.; Lindner, J.; Fassbender, J.ORC
Certain binary alloys exhibit magnetic properties which heavily depend on their structural order/disorder. For example FeAl is paramagnetic in the chemically ordered B2-phase whereas it shows ferromagnetic behavior if the chemically disordered A2-phase is investigated. We will demonstrate that by means of ion irradiation a phase transition from the chemically ordered to the chemically disordered phase can easily be achieved and that temperature treatment leads to the reverse phase transition.
One of the major advantages of ion irradiation is the fact that the interaction is extremely local and hence nanoscale disorder features can directly be written into an ordered environment. This technology is used to create nanoscale ferromagnetic features in a paramagnetic matrix. The achievable magnetic patterning resolution is determined and the magnetic domains as well as stray fields arising from the nanomagnets are imaged.

Reference:
R. Bali et al., Nano Lett. 14, 435 (2014).
Keywords: ion irradiation, magnetism, magnetic domains, patterning
  • Invited lecture (Conferences)
    International Conference on Nanostructuring by Ion Beams, 23.-25.11.2015, Agra, Indien

Permalink: https://www.hzdr.de/publications/Publ-22450
Publ.-Id: 22450


Quasi-two-dimensional Fermi surfaces of the heavy-fermion superconductor Ce2PdIn8

Götze, K.; Klotz, J.; Gnida, D.; Harima, H.; Aoki, D.; Demuer, A.; Elgazzar, S.; Wosnitza, J.; Kaczorowski, D.; Sheikin, I.
We report low-temperature de Haas–van Alphen (dHvA) effect measurements in magnetic fields up to 35 T of the heavy-fermion superconductor Ce2PdIn8. The comparison of the experimental results with band-structure calculations implies that the 4f electrons are itinerant rather than localized. The cyclotron masses estimated at high field are only moderately enhanced, 8m0 and 14m0, but are substantially larger than the corresponding band masses. The observed angular dependence of the dHvA frequencies suggests quasi-two-dimensional Fermi surfaces in agreement with band-structure calculations. However, the deviation from ideal two-dimensionality is larger than in CeCoIn5, to which Ce2PdIn8 bears a lot of similarities. This subtle distinction accounts for the different superconducting critical temperatures of the two compounds.

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Permalink: https://www.hzdr.de/publications/Publ-22449
Publ.-Id: 22449


Ex-Situ Kinetic Investigations of the Formation of the Poly-Oxo Cluster U38

Falaise, C.; Volkringer, C.; Hennig, C.; Loiseau, T.
The ex-situ qualitative study of the kinetic formation of the poly-oxo cluster U38, has been investigated after the solvothermal reaction. The resulting products have been characterized by means of powder XRD and scanning electron microscopy (SEM) for the solid phase and UV/Vis, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and NMR spectroscopies for the supernatant liquid phase. The analysis of the different synthesis batches, stopped at different reaction times, revealed the formation of spherical crystallites of UO2 from t= 3 h, after the formation of unknown solid phases at an early stage. The crystallization of U38 occurred from t=4 h at the expense of UO2, and is completed after t=8 h. Starting from pure uranium(IV) species in solution (t=0–1 h), oxidation reactions are observed with a UIV/UVI ratio of 70:30 for t=1– 3 h. Then, the ratio is inversed with a UIV/UVI ratio of 25/75, when the precipitation of UO2 occurs. Thorough SEM observations of the U38 crystallites showed that the UO2 aggregates are embedded within. This may indicate that UO2 acts as reservoir of uranium(IV), for the formation of U38, stabilized by benzoate and THF ligands. During the early stages of the U38 crystallization, a transient crystallized phase appeared at t=4 h. Its crystal structure revealed a new dodecanuclear moiety (U12), based on the inner hexanuclear core of {U6O8} type, decorated by three additional pairs of dinuclear U2 units. The U12 motif is stabilized by benzoate, oxalates, and glycolate ligands.
Keywords: poly-oxo cluster U38, dodecanuclear cluster U12, XRD, EXAFS, XANES, NMR, SEM, NMR

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Publ.-Id: 22448


Formation of Mississippi Valley-type deposits linked to hydrocarbon generation in extensional tectonic settings: Evidence from the Jabali Zn-Pb-(Ag) deposit (Yemen)

Ostendorf, J.; Henjes-Kunst, F.; Mondillo, N.; Boni, M.; Schneider, J.; Gutzmer, J.
Mississippi Valley-type (MVT) Zn-Pb deposits are widely believed to form in compressional tectonic environments, related to gravity-driven fluid flow. Commonly, they are spatially related to hydrocarbon reservoirs in orogenic foreland settings, but the genetic and temporal links between hydrothermal sulfide mineralization, basin evolution and hydrocarbon generation remains tentative in most cases. We have used direct Rb-Sr chronometry of sphalerite to constrain the age of the Jabali MVT deposit, central Yemen, which is located in the well-studied oil-producing Sab´atayn Basin. A Rb-Sr age of 144.0 ± 4.3 Ma for sulfide mineralization obtained from a quantitative geochronological two-component paleomixing model coincides with a well constrained episode of active rifting, oil generation and expulsion in the Sab´atayn Basin during the Upper Jurassic–Lower Cretaceous.

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Permalink: https://www.hzdr.de/publications/Publ-22447
Publ.-Id: 22447


Tumor volume determination: Demands of radiotherapy on modern radiological imaging

Bütof, R.; Krause, M.
Background: The aim of radiotherapy as a local treatment method is the eradication of all vital tumor cells in order to achieve permanent local tumor control. From a clinical point of view this means that a patient suffering from cancer can only be cured if all cancer stem cells as a specific subpopulation within a tumor are eliminated by the treatment. Results: New radiation techniques often employ lower normal tissue doses with less toxicity and/or the possibility to apply higher radiation doses to the target volume. High-resolution imaging is hereby mandatory for precise tumor volume definition as a basis of local tumor control. New developments in the field of bioimaging lead to further perspectives in radiotherapy. Conclusion: By combining anatomical information with biological characteristics of the tumor, additional benefits for treatment planning and outcome can be achieved. Thus, the use of these modern imaging methods to define irradiation target volumes more clearly forms the basis for the application of modern radiation techniques.
Keywords: Bioimaging; Cancer stem cells; Local tumor control; Radiation oncology; Tumor volume

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Publ.-Id: 22446


PET-based dose painting in non-small cell lung cancer: Comparing uniform dose escalation with boosting hypoxic and metabolically active sub-volumes.

Even, A. J.; van der Stoep, J.; Zegers, C. M.; Reymen, B.; Troost, E. G.; Lambin, P.; van Elmpt, W.
BACKGROUND AND PURPOSE:

We compared two imaging biomarkers for dose-escalation in patients with advanced non-small cell lung cancer (NSCLC). Treatment plans boosting metabolically active sub-volumes defined by FDG-PET or hypoxic sub-volumes defined by HX4-PET were compared with boosting the entire tumour.
MATERIALS AND METHODS:

Ten NSCLC patients underwent FDG- and HX4-PET/CT scans prior to radiotherapy. Three isotoxic dose-escalation plans were compared per patient: plan A, boosting the primary tumour (PTVprim); plan B, boosting sub-volume with FDG >50% SUVmax (PTVFDG); plan C, boosting hypoxic volume with HX4 tumour-to-background >1.4 (PTVHX4).
RESULTS:

Average boost volumes were 507±466cm3 for PTVprim, 173±127cm3 for PTVFDG and 114±73cm3 for PTVHX4. The smaller PTVHX4 overlapped on average 87±16% with PTVFDG. Prescribed dose was escalated to 87±10Gy for PTVprim, 107±20Gy for PTVFDG, and 117±15Gy for PTVHX4, with comparable doses to the relevant organs-at-risk (OAR). Treatment plans are available online (https://www.cancerdata.org/10.1016/j.radonc.2015.07.013).
CONCLUSIONS:

Dose escalation based on metabolic sub-volumes, hypoxic sub-volumes and the entire tumour is feasible. Highest dose was achieved for hypoxia plans, without increasing dose to OAR. For most patients, boosting the metabolic sub-volume also resulted in boosting the hypoxic volume, although to a lower dose, but not vice versa.
Keywords: Dose painting; FDG; HX4; NSCLC; Positron emission tomography; Radiotherapy

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Identification of Patient Benefit From Proton Therapy for Advanced Head and Neck Cancer Patients Based on Individual and Subgroup Normal Tissue Complication Probability Analysis.

Jakobi, A.; Bandurska-Luque, A.; Stützer, K.; Haase, R.; Löck, S.; Wack, L. J.; Mönnich, D.; Thorwarth, D.; Perez, D.; Lühr, A.; Zips, D.; Krause, M.; Baumann, M.; Perrin, R.; Richter, C.
PURPOSE:

The purpose of this study was to determine, by treatment plan comparison along with normal tissue complication probability (NTCP) modeling, whether a subpopulation of patients with head and neck squamous cell carcinoma (HNSCC) could be identified that would gain substantial benefit from proton therapy in terms of NTCP.
METHODS AND MATERIALS:

For 45 HNSCC patients, intensity modulated radiation therapy (IMRT) was compared to intensity modulated proton therapy (IMPT). Physical dose distributions were evaluated as well as the resulting NTCP values, using modern models for acute mucositis, xerostomia, aspiration, dysphagia, laryngeal edema, and trismus. Patient subgroups were defined based on primary tumor location.
RESULTS:

Generally, IMPT reduced the NTCP values while keeping similar target coverage for all patients. Subgroup analyses revealed a higher individual reduction of swallowing-related side effects by IMPT for patients with tumors in the upper head and neck area, whereas the risk reduction of acute mucositis was more pronounced in patients with tumors in the larynx region. More patients with tumors in the upper head and neck area had a reduction in NTCP of more than 10%.
CONCLUSIONS:

Subgrouping can help to identify patients who may benefit more than others from the use of IMPT and, thus, can be a useful tool for a preselection of patients in the clinic where there are limited PT resources. Because the individual benefit differs within a subgroup, the relative merits should additionally be evaluated by individual treatment plan comparisons.

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Publ.-Id: 22444


Regional radiotherapy in high-risk breast cancer: is the issue solved?

Krause, M.; Petersen, C.; Offersen, B. V.; Baumann, M.
Adjuvant radiotherapy is the treatment standard for breast cancer with lymph node metastases after breast-conserving surgery or mastectomy. The inclusion of regional lymph nodes into the treatment volumes has been a question in recent clinical trials. Their impact on treatment standards and open questions is discussed.

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Publ.-Id: 22443


Validation of functional imaging as a biomarker for radiation treatment response.

Jentsch, C.; Beuthien-Baumann, B.; Troost, E. G.; Shakirin, G.
Major advances in radiotherapy techniques, increasing knowledge of tumour biology and the ability to translate these advances into new therapeutic approaches are important goals towards more individualized cancer treatment. With the development of non-invasive functional and molecular imaging techniques such as positron emission tomography (PET)-CT scanning and MRI, there is now a need to evaluate potential new biomarkers for tumour response prediction, for treatment individualization is not only based on morphological criteria but also on biological tumour characteristics. The goal of individualization of radiotherapy is to improve treatment outcome and potentially reduce chronic treatment toxicity. This review gives an overview of the molecular and functional imaging modalities of tumour hypoxia and tumour cell metabolism, proliferation and perfusion as predictive biomarkers for radiation treatment response in head and neck tumours and in lung tumours. The current status of knowledge on integration of PET/CT/MRI into treatment management and bioimage-guided adaptive radiotherapy are discussed.

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Publ.-Id: 22442


Multivariable normal-tissue complication modeling of acute esophageal toxicity in advanced stage non-small cell lung cancer patients treated with intensity-modulated (chemo-)radiotherapy.

Wijsman, R.; Dankers, F.; Troost, E.; Hoffmann, A.; van der Heijden, E.; de Geus-Oei, L.; Bussink, J.
BACKGROUND AND PURPOSE:

The majority of normal-tissue complication probability (NTCP) models for acute esophageal toxicity (AET) in advanced stage non-small cell lung cancer (AS-NSCLC) patients treated with (chemo-)radiotherapy are based on three-dimensional conformal radiotherapy (3D-CRT). Due to distinct dosimetric characteristics of intensity-modulated radiation therapy (IMRT), 3D-CRT based models need revision. We established a multivariable NTCP model for AET in 149 AS-NSCLC patients undergoing IMRT.
MATERIALS AND METHODS:

An established model selection procedure was used to develop an NTCP model for Grade ⩾2 AET (53 patients) including clinical and esophageal dose-volume histogram parameters.
RESULTS:

The NTCP model predicted an increased risk of Grade ⩾2 AET in case of: concurrent chemoradiotherapy (CCR) [adjusted odds ratio (OR) 14.08, 95% confidence interval (CI) 4.70-42.19; p<0.001], increasing mean esophageal dose [Dmean; OR 1.12 per Gy increase, 95% CI 1.06-1.19; p<0.001], female patients (OR 3.33, 95% CI 1.36-8.17; p=0.008), and ⩾cT3 (OR 2.7, 95% CI 1.12-6.50; p=0.026). The AUC was 0.82 and the model showed good calibration.
CONCLUSIONS:

A multivariable NTCP model including CCR, Dmean, clinical tumor stage and gender predicts Grade ⩾2 AET after IMRT for AS-NSCLC. Prior to clinical introduction, the model needs validation in an independent patient cohort.
Keywords: Esophagitis; Intensity-modulated radiation therapy; Non-small cell lung cancer; Predictive models

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Publ.-Id: 22441


ThermAc: A Joint Project on Aquatic Actinide Chemistry and Thermodynamics at Elevated Temperature Conditions

Altmaier, M.; Gaona, X.; Endrizzi, F.; Brendler, V.; Steudtner, R.; Franzen, C.; Tsushima, S.; Panak, P. J.; Skerencak-Frech, A.; Hagemann, S.; Brandt, F.; Krüger, S.; Colàs, E.; Grivé, M.; Thoenen, T.; Kulik, D. A.
The ThermAc project aims at extending the chemical understanding and available thermodynamic database for actinides, long-lived fission products and relevant matrix elements in aquatic systems at elevated temperatures.
  • Poster
    Migration 2015, 13.-18.09.2015, Santa Fe, NM, USA

Permalink: https://www.hzdr.de/publications/Publ-22440
Publ.-Id: 22440


Bulk- und ortsaufgelöste chemische Prozessanalytik in Aufbereitungsprozessen - der steinige Wege zum Erfolg in der Ressourcenanalytik

Renno, A. D.; Rudolph, M.; Schaefer, J.
Der Einsatz chemischer Analysenverfahren zur Überwachung von mineralischen Rohstoffen kann auf eine sehr lange und erfolgreiche Geschichte zurückblicken. Die in den letzten Jahrzehnten stattgefundenen Entwicklungen auf dem Gebiet der chemischen Analytik, insbesondere die verbesserten Möglichkeiten zur Automatisierung und die größere Robustheit einzelner Gerätekomponenten sollten die Einsatzmöglichkeiten in Bergwerken, Aufbereitungsanlagen und metallurgischen Betrieben sehr stark erweitert haben.
Trotzdem liegt der Schwerpunkt der routinemäßig eingesetzten Verfahren zur Zeit bei der off-line Analyse chemischer und mineralogischer Parameter. Neben Bulktechniken kommen insbesondere ortsaufgelöste Verfahren zum Einsatz. Dies sind im Wesentlichen Verfahren der Röntgenfluoreszenzanalyse sowie elektronenstrahlbasierte Verfahren der automatisierten Mineralogie (MLA und QEMSCAN). Im Bereich der Spurenelementanalyse ist dies ICP-MS für die Lösungsanalytik und die Feststoffanalyse (LA-ICP-MS) .
Es wird aufgezeigt, welche Veränderungen in den Bergbau- und Aufbereitungstechnologien notwendig wären, um einen verstärkten Einsatz von in-line Verfahren verbunden mit eventueller Ortsauflösung zu rechtfertigen. Neueste Entwicklungen der Analysentechnik, die großes Potenzial für die Ressourcenanalytik aufweisen, werden vorgestellt.
Keywords: Prozessanalytik
  • Invited lecture (Conferences)
    ANAKON 2015, 23.-26.03.2015, Graz, Österreich

Permalink: https://www.hzdr.de/publications/Publ-22439
Publ.-Id: 22439


What role can and should play ion beam analytical methods in the context of geometallurgy?

Renno, A. D.; Buchriegler, J.; Dreßler, S.; Freiherr, C.; Le Bras, L.; Munnik, F.; Nowak, S.; Scharf, O.; von Borany, J.; Ziegenrücker, R.
Geochemical analysis in the domain of the value-added chain of mineral raw materials is designed to support purposeful the development and improvement of technologies.
Linking chemical and mineralogical data as well as information about the microstructure of ores and gangue minerals with general and specific models of the respective deposits allows the establishment of efficient input data for a targeted impact on mineral processing and metallurgical technologies. These interrelations describe the scientific subfield of geometallurgy. Classical exploration geochemistry and analytical methods for process control are added among it.
This relevancy to technologies and process control implicates specific requirements on the analytical methods regarding accuracy, precision, traceability, but also on availability, response time and sample throughput.
Ion beam analysis (IBA) has a well-earned reputation of an elaborate and complex analytical method, which is furthermore, difficult and strongly regulated to access. In addition is the treatment of the data ambitious and poorly automatable.
What role can and should IBA play in the context of geometallurgy and process control?
We will answer this question on a selection of examples and methods used and developed at the Helmholtz-Institute Freiberg in close cooperation with the Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf. In detail we will show:
1.) the application of the High-Speed PIXE (particle induced X-ray emission) to determine the lateral distribution of trace elements in large samples like drill cores or rock-chips,
2.) the chemical composition (H – U) of reference materials for microanalytical methods using a combination of PIXE, particle induced gamma emission (PIGE), nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS) and
3.) the validation and support of proof of concept and proof of performance procedures of new process analytical methods.
Keywords: Ion Beam Analysis, geometallurgy, PIXE, PIGE
  • Lecture (Conference)
    Geoanalysis 2015, 09.-14.08.2015, Leoben, Österreich

Permalink: https://www.hzdr.de/publications/Publ-22438
Publ.-Id: 22438


High-Speed PIXE: Fast and laterally resolved elemental analysis over wide areas

Renno, A. D.; Buchriegler, J.; Grenzer, J.; Hanf, D.; Merchel, S.; Munnik, F.; Nowak, S.; Scharf, O.; von Borany, J.; Ziegenrücker, R.
A new PIXE (particle-induced X-ray emission) beamline equipped with a full-field energy-dispersive X-ray camera [1,2] has been recently put into operation at HZDR. The so-called High-Speed PIXE is a combination of a 264 x 264 pixel-detector with polycapillary optics guiding the proton-induced X-ray fluorescence radiation towards a pnCCD-chip with an energy resolution of 156 eV (@Mn-Kα). It allows a fast detection of elements over a field of 12 x 12 mm² simultaneously with a lateral resolution better than 100 µm, even at the trace level (<0.1 at.%). A large vacuum sample chamber containing a high-precision sample manipulator (Figure 1) enables a high throughput of even large and heavy samples.
The new set-up is mainly developed for the investigation of geological samples for resource technology research, e.g. analysis of grain composition and intergrowths or determination of rare earth element distributions. The simultaneous measurement of a big array of pixel enables a fast overview over a large region of the sample with first results becoming visible almost immediately. Together with the PIXE-PIGE (particle-induced gamma-emission) implementation at the classical micro-beamline at HZDR (~3 µm resolution) this new approach allows analysis of most of the elements of interest in mineralogy and resource technology research.
First results concerning lateral resolution and detection limits of geological samples are encouraging. Due to the low background in the PIXE spectra investigation of the lateral distribution of trace elements is possible in unrivalled time.

[1] O. Scharf et al., Anal. Chem., 2011, . 83, 2532.
[2] I. Ordavo et al., NIM A, 2011, . 654, 250.
Keywords: High-Speed PIXE, PIXE
  • Lecture (Conference)
    Workshop für Ionenstrahlen und Nanostrukturen, 22.-24.07.2015, Heidelberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22437
Publ.-Id: 22437


Design of new 18F-labelled radiopharmaceuticals for brain tumor imaging

Brust, P.
Glioblastoma multiforme is the most aggressive type of primary brain tumor with a median overall survival (OS) of about 12 months. Brain metastases are the most common form of brain tumors and significantly outnumber primary brain tumors, with the majority originating from lung cancer, especially non–small cell lung cancer (NSCLC). Despite aggressive treatment, their prognosis is also poor with a median OS of approximately 7 months after diagnosis. Treatment of those tumors remains one of the most challenging tasks in clinical oncology. Although new molecular pathways in tumor biology are being constantly discovered, translation of basic science achievements into clinical practice is rather slow. Major obstacles in resistance to therapy are heterogeneity of brain tumors, multiple genetic alterations, and their diffuse, infiltrative behaviour. Hence identifying and investigating pathways related to tumor etiology and growth is highly important. Positron emission tomography (PET) offers the potential to identify key signaling pathways in brain tumors involving neurotransmitters and -modulators and to discover drugs which may be used for their therapy.
One of the most important prerequisites for PET is the development and evaluation of radiolabelled ligands in order to investigate brain functions in living human subjects. Fluorine-18 is currently the most favorable radionuclide that is routinely used for radiolabeling because of its half-life of 109.8 min. The use of PET radioligands provides brain images of transport, metabolic and neurotransmission processes on the molecular level. PET is currently the most sensitive and specific method for this type of studies. Through integration of chemical/radiochemical, pharmaceutical/radiopharmaceutical, biochemical and radiopharmacological basic research, computational chemistry and with the aid of nuclear medicine diagnostic new approaches in brain tumor treatment will be made available. The presentation will focus on the strategy of radiotracer development bridging from basic science to biomedical application focusing on targets of major importance for the mentioned tumors such as cannabinoid, sigma and nicotinic alpha7 receptors.
  • Lecture (Conference)
    Cancer-2016, 04.-06.04.2016, Baltimore, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-22436
Publ.-Id: 22436


Spatiotemporal monitoring of geochemical transport processes with Positron Emission Tomography (PET) - a useful tool for CEBAMA partners

Kulenkampff, J.
Es ist kein Abstract vorhanden.
  • Lecture (others)
    IGD-TP 6th Exchange Forum, 03.-04.11.2015, London, Großbritannien

Permalink: https://www.hzdr.de/publications/Publ-22435
Publ.-Id: 22435


From REE-Enrichment to REE Deposits – An Overview

Möckel, R.; Kempe, U.; Gutzmer, J.
Despite their name, rare earth elements (REE, La–Lu) are not rare. As a matter of fact, they are three orders of magnitude more abundant in the Earth’s Crust than for example gold (e.g. Wedepohl, 1995). Ore-forming processes produce local enrichments in which the concentration of gold may exceed its average crustal abundance by a factor of 1000 – or more. Rare earth elements, in contrast, are widely and evenly disseminated in the Earth’s Crust – they are rarely enriched to form economic concentrations that may then be exploited as ore deposits.
Despite being rather scarce, REE enrichments may form by a number of geological processes. Consequently, a number of classifications exist in literature for REE deposits. Broadly, REE deposits of magmatic affiliation can be distinguished from REE deposits of hydrothermal and sedimentary origin. The latter include marine (heavy mineral) placer deposits, residual ion adsorption clays (IACs) as well as highly REE-enriched lateritic caprocks developed at the expense of REE-enriched protoliths. Magmatic deposits include, most importantly, REE enrichment in igneous rocks such as alkaline to peralkaline and carbonatite rocks, as well as rare metal enriched pegmatites. The least common type of REE deposit is of hydrothermal origin, including monazite and/or xenotime-rich vein and breccia-type mineralization. Combinations of above-mentioned ore-forming processes are known or under discussion (e.g. Drew et al. 1990, Dostal et al. 2014, Kempe et al. 2015), resulting in complex mineralisation styles, complex mineral assemblages and multi-stage paragenetic sequences. It is therefore not surprising that the assignment to one or another type is ambiguous in some cases.
Despite obvious genetic complexity and a multitude of ore-forming environments, more than 90% of the world’s recent REE production stems from (virtually) monomineralic ores, including the Bayan Obo deposit (China), the Mountain Pass deposit (USA) and the Mt. Weld deposit (Australia). The former two are pristine magmatic carbonatites, whereas the latter is a lateritic deposit formed by enrichment of a carbonatite intrusion (Long et al. 2010). Bastnaesite, a REE-fluoride-carbonate, is the only important ore mineral at Mountain Pass, monazite, a REE phosphate clearly predominates at Mt. Weld, whereas both of these common REE-minerals are widespread at Bayan Obo.
REE mineral-bearing placer deposits are well known in the marine environment. They always contain monazite as the quantitatively most important REE-mineral, with xenotime, a Y-HREE phosphate closely related to monazite, a distant second. Such placer deposits are, however, currently only exploited for REE in India.
Needless to say, all of the deposit types described above are highly enriched only in light REE (LREE), whereas the highly coveted heavy REE (HRREE) are present only in very minor concentrations. HREE are mostly extracted from ion adsorption clay deposits in southern China. These deposits are the product of intensive chemical weathering of only mildly REE-enriched granites in a warm and humid climate. REE are remobilized during weathering and adsorbed to the surface of clay minerals. There are thus no clear REE minerals present – and exploitation is by in-situ leaching rather than conventional mining (Orris & Grauch, 2002).
Because demand in particular for HREE for high tech applications is rapidly increasing, other REE occurrences with more exotic and more complex mineralogies have been have recently come into focus. This includes alkaline igneous complexes, e.g., in Russia (Lovozero), Canada (Strange Lake, Thor Lake), Sweden (Norra Kärr) and several localities in Greenland. Some of these deposits are hydrothermally altered, leading to considerable increase of REE contents and other valuable elements. Such processes of hydrothermal alteration do not only result in an increase of REE concentration, also a complex assemblage of REE minerals (e.g. Kempe et al. 2015).


References:

Dostal, J., Kontak, D.J. and Karl, S.M. (2014): The early jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska): Geochemistry, petrogenesis and rare-metal mineralization. Lithos 202–203:395–412
Drew, L.J., Qingrun, M. and Weijun, S. (1990): The Bayan Obo iron-rare-earth-niobium deposits, Inner Mongolia, China. Lithos 26:43–65
Kempe, U., Möckel, R., Grauner, T. Kynicky, J. and Dombon, E. (2015): The genesis of Zr-Nb-REE mineralisation at Khalzan Buregte (Western Mongolia) reconsidered. Ore Geology Reviews 64: 602–625
Long, K.R., Van Gosen, B.S., Foley, N.K. and Cordier, D. (2010): The principal rare earth element deposits of the United States – A summary of domestic deposits and a global perspective. USGS Scientific Investigations Report 2010-5220
Orris, G.J. and Grauch, R.I. (2002): Rare earth element mines, deposits, and occurences. USGS Open-File Report 02-189
Wedepohl, K.H. (1995): The composition of the continental crust, Geochimica et Cosmochimica Acta, 59(7):1217–1232
Keywords: rare earth elements
  • Invited lecture (Conferences)
    AREE 2015 - Analysis of Rare Earth Elements Methods and Applications International Colloquium and Exhibition, 05.-06.10.2015, Kleve, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22434
Publ.-Id: 22434


Measurement and modelling of reactive transport in geological barriers for nuclear waste containment

Xiong, Q.; Joseph, C.; Schmeide, K.; Jivkov, A. P.
Compacted clays are considered as excellent candidates for barriers to radionuclide transport in future repositories for nuclear waste due to their very low hydraulic permeability. Diffusion is the dominant transport mechanism, controlled by a nano-scale pore system. Assessment of the clays’ long-term containment function requires adequate modelling of such pore systems and their evolution. Existing characterisation techniques do not provide complete pore space information for effective modelling, such as pore and throat size distributions and connectivity. Special network models for reactive transport are proposed here using the complimentary character of the pore space and the solid phase. This balances the insufficient characterisation information and provides the means for future mechanical-physical-chemical coupling. The anisotropy and heterogeneity of clays is represented using different length parameters and percentage of pores in different directions. Resulting networks are described as mathematical graphs with efficient discrete calculus formulation of transport. Opalinus Clay (OPA) is chosen as an example. Experimental data for the tritiated water (HTO) and U(VI) diffusion through OPA are presented. Calculated diffusion coefficients of HTO and uranium species are within the ranges of the experimentally determined data in different clay directions. This verifies the proposed pore network model and validates that uranium complexes are diffusing as neutral species in OPA. In the case of U(VI) diffusion the method is extended to account for sorption and convection. Rather than changing pore radii by coarse grained mathematical formula, physical sorption is simulated in each pore, which is more accurate and realistic.
Keywords: Reactive transport, pore network model, Opalinus Clay, pore shapes

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Permalink: https://www.hzdr.de/publications/Publ-22433
Publ.-Id: 22433


Analysis of buoyancy-driven flow in the ROCOM test facility

Feng, Q.; Bieder, U.; Höhne, T.
Mixing of coolant with different boron content and/or different temperature in the primary system of pressurized water reactors (PWR) plays an important role during normal operation and under accident conditions [1]. In emergency core cooling (ECC) situations after a loss of coolant accident, cold ECC water is injected into the hot water of the cold leg and downcomer. Temperature distributions near the wall and temperature gradients in time are important to be known for the assessment of thermal stresses (Pressurized Thermal Choc).
Numerous experiments were realized in the test facility ROCOM of the Helmholz Zentrum Dresden-Rossendorf, Dresden, Germany, ([2], [3]) to investigate the effects of density differences between the primary loop inventory and the ECC water on the mixing in the downcomer. The mass flow rate in the hot leg was varied between 0 and 15% of the nominal flow rate, to keep it at the order of magnitude of natural circulation flow. The density differences between ECC and loop water were varied between 0 and 10% in order to simulate cold water injection. In 2005, an experiment with 5% flow rate in loop 1 and 10% density difference between ECC and loop water were compared to CFD calculations with Trio_U [1]. The Froude number is Fr=0.366, which is labelled as density-dominated. The same experiment is analyzed here with the TrioCFD code, taking into account 10 years of code and hardware development.
Keywords: ROCOM, Mixing, RPV
  • Contribution to proceedings
    IYNC2016 - International Youth Nuclear Congress, 24.-30.07.2016, Hangzhou, China
  • Open Access Logo Energy Procedia 127(2017), 44-53
    DOI: 10.1016/j.egypro.2017.08.062

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Permalink: https://www.hzdr.de/publications/Publ-22432
Publ.-Id: 22432


Mineralogija rud nefelina glubokich gorizontov Kija-Šaltyrskogo mestoroždenija

in Russian
Shalisman, T.
In the framework of the thesis several minerals were analyzed in the Helmholtz-Institute Freiberg and in the Helmholtz-Zentrum Dresden-Rossendorf. The used methods are Mineral Liberation Analysis (MLA), Electron probe micro analysis (EPMA) and Particle Induced X-ray Analysis (PIXE). The data were interpreted and compared to published mineralogical, petrographical and geochemical data.
Keywords: Nepheline ore, Kiya Shaltyr, Siberia, Mineral Liberation Analysis, EPMA, PIXE
  • Diploma thesis
    Siberian Federal University, 2015
    Mentor: Prof. A.M. Sazonov, Prof. S.I. Leont'ev, Dr. Axel Renno
    89 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-22430
Publ.-Id: 22430


Petrografija i petrochimija glubokich gorizontov Kija-Šaltyrskogo mestoroždenija nefelina

in Russian
Iakovleva, E.
Das Ergebnis der Untersuchungen ist eine petrographische Beschreibung der Hauptgesteinstypen und ihrer petrochemischen Besonderheiten. Des weiteren wird die Verteilung dieser Gesteinstypen in der Lagerstätte sowie die Verteilung der salischen und mafischen Komponenten im Detail beschrieben und statistisch ausgewertet. Dies ermöglichte die Erarbeitung eines Modells der einzelnen Erzkörper in der Lagerstätte. Ein genetisches Modell sowie Vorschläge zur Abbauführung wurden erarbeitet.
Keywords: Petrography, nepheline ore, Kiya Shaltyr, Siberia
  • Diploma thesis
    Siberian Federal University, 2015
    Mentor: Prof. A.M. Sazonov, Prof. S.I. Leont'ev, Dr. Axel Renno
    104 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-22429
Publ.-Id: 22429


Expect the unexpected – automated mineralogical analysis of secondary raw materials

Dreßler, S.; Bachmann, K.; Haser, S.; Heinig, T.; Schaefer, J.; Scharf, O.
Secondary raw materials are becoming increasingly more important in ensuring the stability of critical metal supply. Ashes, slags, dusts and other industrial residues are produced in large quantities.
Precise and accurate chemical and mineralogical data, knowledge of distribution of valuable and deleterious elements in the single phases as well as information about homogeneity and grain size distribution of the minerals are crucial for the development of new extraction technologies.
Gaining these essential information can be achieved by using SEM-based, X-ray-based and Proton-induced methods of automated mineralogical analysis.
However, the large particle size range, the dominance of very small grain sizes (< 5 µm) and the diversity of phases are challenging for such types of analysis. Furthermore, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. Initial results of ash and slag samples done with the MLA (electron-based), the High-Speed PIXE (Particle Induced X-Ray Emission) and a the new XRF Mine Analyzer (X-Ray Fluorescence) will be presented and evaluated.
Keywords: Automated Mineralogy, Secondary Raw Materials, MLA, High-Speed PIXE, XRF Mine Analyzer
  • Invited lecture (Conferences)
    VII International Congress & Exhibition “NON-FERROUS METALS and MINERALS”, 14.-17.09.2015, Krasnoyarsk, Russland

Permalink: https://www.hzdr.de/publications/Publ-22428
Publ.-Id: 22428


Analysis of the coolant density reactivity coefficient in LFRs and SFRs via Monte Carlo perturbation/sensitivity

Aufiero, M.; Fratoni, M.; Fridman, E.; Lorenzi, S.
The coolant density coefficient represents one of the main reactivity feedback in Lead-cooled Fast Reactors (LFRs) and Sodium-cooled Fast Rectors (SFRs), and its accurate calculation is important for a correct evaluation of the dynamic of these systems. Coolant density reactivity maps have been calculated in the past adopting perturbation theory in deterministic codes. Usually, full-core simulations employed multi-group diffusion codes or 2D (r, z) geometrical approximations. Nowadays, Monte Carlo neutron transport simulations are commonly adopted for the study of LFR and SFR. Nonetheless, reactivity feedback is usually calculated via direct perturbations, i.e., comparing the effective multiplication factor of two separate Monte Carlo runs. When small effects are to be investigated via the direct perturbation approach, the adoption of either large system perturbations or a large number of simulated particles is required, in order to reduce the statistical errors. Moreover, if spatial maps of coolant density reactivity coefficient are to be generated via direct perturbation, one criticality source Monte Carlo simulation is required for each spatial region. In this view, the sensitivity/perturbation method offer the advantage of producing a large number of sensitivity coefficients is a single calculation. More important, this approach allows decomposing reactivity effects by energy and reaction for a deeper investigation of the feedback. In this work, two LFR and SFR core designs are considered, focusing on the calculation and analysis of the coolant density reactivity coefficient. The space-dependent lead and sodium density reactivity worth are calculated adopting the sensitivity/perturbation capabilities recently implemented in an extended version of the Serpent-2 code , previously adopted for the calculation of coolant void maps . The present work focuses on the validation of the sensitivity/perturbation results against direct perturbation calculations, on the analysis of the optimal parameters to be adopted for the simulations and on the discussion of the peculiar results obtained for the two considered cases.
  • Contribution to proceedings
    PHYSOR 2016, 01.-05.05.2016, Sun Valley, ID, USA
    Proceedings of PHYSOR 2016

Permalink: https://www.hzdr.de/publications/Publ-22427
Publ.-Id: 22427


Axial fuel rod expansion model in nodal code DYN3D for SFR application

Nikitin, E.; Fridman, E.
The nodal diffusion code DYN3D (Grundmann et al., 2000, 2005) is under extension for Sodium cooled Fast Reactor (SFR) application. As a part of the extension new models for thermal expansion reactivity feedbacks are needed. One of these is the reactivity feedback of the axial fuel rod expansion, which is dependent on local temperatures. The difficulty in the modeling of this effect with nodal codes can be attributed to the inflexibility of the nodal mesh i.e. all nodes in a same axial layer have to be of an identical height. This restricts the modeling to a simplified case of the radially uniform axial expansion.

In this study a new model for the treatment of axial fuel rod expansions was developed and implemented in DYN3D. The idea of the model was to preserve the axial size of the nodes and to account for the axial expansion effects by manipulation of homogenized few-group cross sections (XS). In this way the rigid nodal discretization can remain unchanged, and each node can be treated separately depending on its degree of expansion. The model recombines (“mixes”) the XS for the affected nodes, depending on the contribution of the expanded materials inside of the node.
Keywords: Thermal expansion, SFR, Monte Carlo, Serpent, Nodal diffusion method, DYN3D
  • Contribution to proceedings
    PHYSOR 2016, 01.-05.05.2016, Sun Valley, ID, USA
    Proceedings of PHYSOR 2016
  • Lecture (Conference)
    PHYSOR 2016, 01.-05.05.2016, Sun Valley, ID, USA

Permalink: https://www.hzdr.de/publications/Publ-22425
Publ.-Id: 22425


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