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34877 Publications

The attempt of using GaN as a photocathode in SRF Gun II

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
GaN is a semi-conductive material that is well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required. It has also a wide wavelength range from 100 to 380 nm.

Doping elements for n-type is silicon (Si) and for p-type magnesium (Mg). Mostly p-doped GaN promises better conditions because magnesium atoms increase the minority carrier diffusion length (about 200 nm). MOVPE is the most used technique to produce p-type GaN. Low temperatures are required in comparison to undoped or n-type GaN. Afterwards an annealing process is necessary to remove magnesium-bonded hydrogen. In p-type GaN electron are the minority carriers whereas holes are the majority carriers. The doping is assumed to lower the band bending around the surface. Therefore, the vacuum level is shifted to lower energy than the conductive band minimum in the flat band region.
Activated with a thin alkali metal layer, like caesium, GaN has the ability to lower the surface work function to produce a negative electron affinity (NEA). This effect originates from the surface band bending. Electrons excite over the bandgap and can easily enter into the vacuum.

Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
Like caesium telluride cathode it is possible to recover GaN(Cs) about 50% of the original QE with a simple bake out of 200°C and doing a Cs-reactivation to recover the degraded
cathode [2].
A big advantage of visible light cathodes instead of UV cathodes is to relax the drive laser requirements.

[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.
[2] Siegmund, O. et al. 2006. “Development of GaN Photocathodes for UV Detectors.” 567:89–92

Keywords: GaN(Cs) photocathode; III-V semiconductor; NEA photocathode; thin layer deposition

  • Open Access Logo Lecture (Conference)
    ECASIA 2019-European Conference on Applications of Surface and Interface Analysis, 15.-20.09.2019, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31112
Publ.-Id: 31112


Emittance measurements comparison of slit-scan and quadrupole scan in simulation and experiments

Ma, S.; Arnold, A.; Evtushenko, P.; Ryzhov, A.; Schaber, J.; Teichert, J.; Xiang, R.

Three quadrupoles and one screen are used for beam transverse emittance measurements at HZDR ELBE. In this paper, the emittance calculated with two different methods, one with thin-lens approximation and the other one thick-lens no approximation, are compared and analized. To analyze the measurement error, quadrupole calibration is need. Two aspects about quadrupole analysis are made. The first one is quadrupole’s effective length and strength and the second one is quadrupole’s converged or diverged ability in reality.

  • Poster
    The 19th International Conference on RF Superconductivity, SRF2019, 30.06.-05.07.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-31111
Publ.-Id: 31111


Study of using GaN(Cs) as a photocathode in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Murcek, P.; Zwartek, P.; Arnold, A.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: GaN photocathode; caesium activation; thin layer deposition, NEA photocathode

  • Open Access Logo Poster
    19th International Conference on RF Superconductivity, SRF2019, 30.06.-05.07.2019, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31110
Publ.-Id: 31110


The attempt of using GaN(Cs) in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Murcek, P.; Zwartek, P.; Arnold, A.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: GaN; NEA activation; photocathode; thin layer deposition

  • Open Access Logo Poster
    EWPAA 2019: European workshop on photocathodes for particle accelerator applications, 11.-13.09.2019, Villingen, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-31109
Publ.-Id: 31109


Study of surface cleaning and Cs-activation on GaN photocathodes

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams. With such a high intensity and short wavelengths, amorphous materials and chemical reaction steps nowadays could be studied.
GaN is a semi-conductive material that is well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is only used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
It has also a wide wavelength range from 100 to 380 nm.
The equilibrium phase of GaN is wutzite, which means gallium atoms are tetrahedrically surrounded by nitride atoms in a hexagonal closed crystal structure. The tetrahedrons build alternating bilayers of Ga and N in c-direction.
Doping elements for n-type is silicon (Si) and for p-type magnesium (Mg). Mostly p-doped GaN promises better conditions because magnesium atoms increase the minority carrier diffusion length (about 200 nm). MOVPE is the most used technique to produce p-type GaN. Low temperatures are required in comparison to undoped or n-type GaN. Afterwards an annealing process is necessary to remove magnesium-bonded hydrogen. In p-type GaN electron are the minority carriers whereas holes are the majority carriers. The doping is assumed to lower the band bending around the surface. Therefore, the vacuum level is shifted to lower energy than the conductive band minimum in the flat band region.
Activated with a thin alkali metal layer, like caesium, GaN has the ability to lower the surface work function to produce a negative electron affinity (NEA). This effect originates from the surface band bending. Electrons excite over the band gap and can easily enter into the vacuum.
Generally, the stability has also a great influence on the potential application in high brightness guns. GaN shows the promise of more significant stability and robustness against vacuum contaminations than alternate photocathodes.
Like caesium telluride cathode it is possible to recover GaN(Cs) about 50% of the original QE with a simple bake out of 200°C and doing a Cs-reactivation to recover the degraded
cathode [2].
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency GaN-Based Photocathodes with Extremely High Quantum Efficiency.” 103511(2005):1–4.
[2] Siegmund, O. et al. 2006. “Development of GaN Photocathodes for UV Detectors.” 567:89–92.

Keywords: photocathode; GaN; NEA activation

  • Open Access Logo Poster
    DPG Summer school 2019- Exciting nanostructures: Characterizing advanced confined systems, 22.-27.07.2019, Bad Honnef, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31108
Publ.-Id: 31108


The attempt of using GaN (Cs) as a photocathode in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green).
An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: photocathode; semiconductor; NEA activation; surface analysis

  • Open Access Logo Poster
    DPG Frühjahrstagung, 18.-22.03.2019, München, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31107
Publ.-Id: 31107


The attempt of using GaN as a photocathode in SRF Gun II

Schaber, J.; Xiang, R.; Murcek, P.; Arnold, A.; Teichert, J.; Ma, S.; Zwartek, P.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

  • Open Access Logo Lecture (Conference)
    5. Annual MT Meeting, 04.-07.03.2019, Jena, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31106
Publ.-Id: 31106


KLOE hadronic cross section data in the HepDATA repository

Müller, S.

Presentation at (remote) Kick-Off-Meeting of the PrecisionSM-Working group of the STRONG2020 EU Project.

Keywords: KLOE; HEPdata

  • Open Access Logo Lecture (Conference) (Online presentation)
    Kick-Off meeting for PrecisionSM working group of STRONG2020 project, 03.06.2020, ZOOM (Sweden), Sweden

Permalink: https://www.hzdr.de/publications/Publ-31105
Publ.-Id: 31105


Dataset for dynamic simulation of the CEFR control rod drop experiments

Fridman, E.

Dataset for dynamic simulation of the CEFR control rod drop experiments 

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-03
    DOI: 10.14278/rodare.353

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Permalink: https://www.hzdr.de/publications/Publ-31104
Publ.-Id: 31104


ESFR-SMART WP1.2.1 dataset

Fridman, E.

ESFR-SMART WP1.2.1 dataset

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-03
    DOI: 10.14278/rodare.351

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Permalink: https://www.hzdr.de/publications/Publ-31102
Publ.-Id: 31102


Helmholtz AI For Matter at Helmholtz-Zentrum Dresden-Rossendorf

Steinbach, P.; Hoffmann, N.

This poster summarizes the Helmholtz AI local unit for Matter Research installed at HZDR. The poster was presented at the Helmholtz AI Kick-Off Meeting on March 5th, 2020, in Munich, Germany.

Keywords: Helmholtz AI; FWCC; Deep Learning; Machine Learning; Data Science; Kick-Off

  • Open Access Logo Poster (Online presentation)
    Helmholtz AI Kick-Off Meeting, 05.03.2020, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31099
Publ.-Id: 31099


Neutronic analysis of the European Sodium Fast Reactor: Part II - burnup results

Fridman, E.; Álvarez-Velarde, F.; Romojaro-Otero, P.; Tsige-Tamirat, H.; Jiménez-Carrascosa, A.; García-Herranz, N.; Bernard, F.; Gregg, R.; Krepel, J.; Massara, S.; Poumerouly, S.; Girardi, E.; Mikityuk, K.

In the framework of the Horizon 2020 project ESFR-SMART, the European Sodium Fast Reactor (ESFR) core was updated through a safety-related modification and optimization of the core design from the earlier FP7 CP-ESFR project.

This study is dedicated to neutronic analysis of the new SFR core. The conducted work is reported in two parts. Part I dealt with the evaluation of the safety-related neutronic parameters of the fresh core carried out by 8 organizations using both continuous energy Monte Carlo and deterministic computer codes. A special emphasis was put on the calibration and verification of the computational tools involved in the analyses.

Part II is devoted to once-through and realistic batch-wise burnup calculations aiming at the establishing of the equilibrium core state, which will later serve as a basis for detailed safety analyses.

Keywords: ESFR; safety; Horizon 2020

Related publications

  • Journal of Nuclear Engineering and Radiation Science (2021)
    Online First (2020) DOI: 10.1115/1.4048765

Permalink: https://www.hzdr.de/publications/Publ-31098
Publ.-Id: 31098


Neutronic analysis of the European Sodium Fast Reactor: Part I - fresh core results

Fridman, E.; Álvarez-Velarde, F.; Romojaro-Otero, P.; Tsige-Tamirat, H.; Jiménez-Carrascosa, A.; García-Herranz, N.; Bernard, F.; Gregg, R.; Krepel, J.; Massara, S.; Poumerouly, S.; Girardi, E.; Mikityuk, K.

In the framework of the Horizon 2020 project ESFR-SMART (2017-2021), the European Sodium Fast Reactor (ESFR) core was updated through a safety-related modification and optimization of the core design from the earlier FP7 CP-ESFR project (2009-2013).

This study is dedicated to neutronic analyses of the improved ESFR core design. The conducted work is reported in two parts. Part I deals with the evaluation of the safety-related neutronic parameters of the fresh Beginning-of-Life (BOL) core carried out by 8 organizations using both continuous energy Monte Carlo and deterministic computer codes. In addition to the neutronics characterization of the core, a special emphasis was put on the calibration and verification of the computational tools involved in the analyses.

Part II is devoted to once-through and realistic batch-wise burnup calculations aiming at the establishing of the equilibrium core state, which will later serve as a basis for detailed safety analyses.

Keywords: ESFR; Safety; Horizon 2020

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31097
Publ.-Id: 31097


Dynamic simulation of the CEFR control rod drop experiments with the Monte Carlo code Serpent

Fridman, E.; Huo, X.

The China Experimental Fast Reactor (CEFR) is the first SFR operated in China. The CEFR physical start-up tests, conducted in 2010, included control rod (CR) worth (CRW) measurements by the rod drop method.
In this study, the transient simulations of the actual course of the CR drop experiments have been performed with the Monte Carlo code Serpent using a detailed 3D heterogeneous model of the CEFR core. The estimated time-depended neutron population, dynamic reactivity, and CRWs have been compared to the measurements. The experimental and calculated reactivity curves have shown a very close behavior for the entire simulated time interval. With regard to the CRW results, a very good compliance between the experiment and simulations as well as among the applied computational approaches has been observed. The obtained results indicate that Serpent can be routinely applied to transient simulations, the area which until recently was limited to deterministic methods.

Keywords: CEFR; Serpent; dynamic Monte Carlo; rod drop experiments

Related publications

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  • Secondary publication expected from 20.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31096
Publ.-Id: 31096


Laboratory study of stationary accretion shock relevant to astrophysical systems

Mabey, P.; Albertazzi, B.; Falize, E.; Michel, T.; Rigon, G.; van Box Som, L.; Pelka, A.; Brack, F.-E.; Kroll, F.; Filippov, E.; Gregori, G.; Kuramitsu, Y.; Lamb, D. Q.; Li, C.; Ozaki, N.; Pikuz, S.; Sakawa, Y.; Tzeferacos, P.; Koenig, M.

Accretion processes play a crucial role in a wide variety of astrophysical systems. Of particular interest are magnetic cataclysmic variables, where, plasma flow is directed along the star’s magnetic field lines onto its poles. A stationary shock is formed, several hundred kilometres above the stellar surface; a distance far too small to be resolved with today’s telescopes. Here, we report the results of an analogous laboratory experiment which recreates this astrophysical system. The dynamics of the laboratory system are strongly influenced by the interplay of material, thermal, magnetic and radiative effects, allowing a steady shock to form at a constant distance from a stationary obstacle. Our results demonstrate that a significant amount of plasma is ejected in the lateral direction; a phenomenon that is under-estimated in typical magnetohydrodynamic simulations and often neglected in astrophysical models. This changes the properties of the post-shock region considerably and has important implications for many astrophysical studies.

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Permalink: https://www.hzdr.de/publications/Publ-31094
Publ.-Id: 31094


Helmholtz AI Consultants at Helmholtz-Zentrum Dresden-Rossendorf

Steinbach, P.

This poster summarizes the dedicated Helmholtz AI consultant team installed at HZDR. The poster was presented at the Helmholtz AI Kick-Off Meeting on March 5th, 2020, in Munich, Germany.

Keywords: Helmholtz AI; consultants; Local Unit; Matter; Kick-Off

  • Open Access Logo Poster
    Helmholtz AI Kickoff, 05.03.2020, München, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31093
Publ.-Id: 31093


Directed, elliptic and higher order flow harmonics of protons, deuterons and tritons in Au+Au collisions at sqrt(s_NN)=2.4 GeV

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Ciepal, I.; Deveaux, C.; Dreyer, J.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gernhäuser, R.; Golosov, O.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kohls, M.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Malige, A.; Mamaev, M.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Pysz, K.; Ramos, S.; Ramstein, B.; Rathod, N.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Singh, U.; Smyrski, J.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Ströbele, H.; Stroth, J.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wójcik, D.; Zanevsky, Y.; Zumbruch, P.

Flow coefficients vn of the orders n=1−6 are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at sqrt(s_NN)=2.4 GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a complete, multi-differential picture of the emission pattern of these particles. The ratio v4/v22 at mid-rapidity is found to be remarkably close to the value 0.5, as might be indicative for an ideal fluid scenario.

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Permalink: https://www.hzdr.de/publications/Publ-31092
Publ.-Id: 31092


Recent insights in barium-131 as a diagnostic match for radium-223: cyclotron production, separation, labeling and imaging

Reissig, F.; Bauer, D.; Ullrich, M.; Kreller, M.; Pietzsch, J.; Mamat, C.; Kopka, K.; Pietzsch, H.-J.; Walther, M.

Barium-131 is a promising SPECT-compatible radionuclide for nuclear medicine and a promising diagnostic match for the alpha emitters radium-223/-224 by providing similar chemical properties as well as physical half-lives. Methods: Herein, we report on the sufficient production route 133Cs(p,3n)131Ba by using 28 MeV proton beams. Moreover, a sufficient purification process, based on SR Resin, was applied. For the first time, radiolabeling of macropa (literature-known chelator) with barium-131 was performed. Biodistribution studies and small animal SPECT/CT measurements were carried out with [131Ba]Ba(NO3)2 as reference and 131Ba-labeled macropa. Results: An average of 190 MBq barium-131 per irradiation was obtained. The purification process led to barium-131 in high radiochemical purity. Only an isotopic impurity of 0.01% barium-133 was detectable. Radiolabeling methods under mild conditions and reaction controls based on TLC systems were successfully applied for the labeling of the chelator macropa. For the first time, small animal SPECT imaging was performed using [131Ba]Ba(NO3)2 and 131Ba-labeled macropa in healthy mice. Biodistribution studies revealed the expected rapid bone uptake of [131Ba]Ba2+ ions, whereas 131Ba-labeled macropa showed a fast clearance from the blood, thereby showing a significantly (P < 0.001) lower accumulation in the bone. Conclusion: Barium-131 is a promising SPECT radionuclide and delivers appropriate imaging qualities in small animals. Furthermore, the relative stability of the 131Ba-labeled macropa complex in vivo forms the basis for the development of sufficient new chelators for heavy alkaline earth metal ions, especially for radium isotopes. Those radionuclides and the necessary stable chelation are of great interest in the research field of targeted alpha therapy. Thereby, barium-131 will reveal its meaning as diagnostic match to the alpha emitters radium-223 and radium-224.

Keywords: barium-131; cyclotron production; radionuclide separation; macropa; small animal SPECT

Permalink: https://www.hzdr.de/publications/Publ-31091
Publ.-Id: 31091


Corrigendum to “Controls on strath terrace formation and evolution: The lower Guadiana River, Pulo do Lobo, Portugal”

Ortega-Becerril, J. A.; Garzón, G.; Tejero, R.; Meriaux, A.-S.; Delunel, R.; Merchel, S.; Rugel, G.

The authors regret publishing the original article while omitting four authors. The correct author list and affiliations have now been corrected.
We would also like to make the clarifications and corrections listed below on the cosmogenic radionuclide (CRN) analysis.
1) All ¹⁰Be samples were collected in 2010 and prepared at the Newcastle Cosmogenic Isotope Laboratory. Accelerator mass spectrometry (AMS) of ¹⁰Be was performed in 2011 at the DREAMS-facility at the Helmholtz-ZentrumDresden-Rossendorf (HZDR) (Akhmadaliev et al., 2013).
2) All the ¹⁰Be model ages were calculated similarly to Mériaux et al. (2012). Spallation and muon production rate schemes are compatible with the CRONUS-Earth calculator v2.2 using the mid-latitude attenuation length of Farber et al. (2008). Ζero erosion model ages were calculated similarly than the Stone/Lal scaling scheme of Balco et al. (2008) with a constant production rate “St” for ¹⁰Be of 4.49 ± 0.39 atoms/g·year instead of the updated 4.01 ± 0.32 atoms/g·year for that scheme by Phillips et al. (2016). The “St” model ages are corrected for the production rate update. Thickness corrections assume a density of ρ = 2.65 g/cm³ for each sample.
The topographic shielding is derived from topographic data collected in the field. The propagated analytical uncertainties include
error blank, carrier, counting statistics and the uncertainty of the standard-like material SMD-Be-12 (Akhmadaliev et al., 2013). The propagated uncertainties include statistical uncertainties from the AMS, 8% uncertainty on the production rate, 0.87% for the decay constants of ¹⁰Be (Korschinek et al., 2010), as well as uncertainty of 5% on the density and 2.25% on the attenuation length of 177 ± 4 g/cm² (Farber et al., 2008). The ages are given in ka. Table 2 has been corrected and completed with the time-dependent model ages calculated using the “LSDn” scaling model (Lifton et al., 2014).
These “LSDn” model ages integrate the variation of the magnetic field over time together with the non-dipole field components and up-to-date spallation and muon scaling schemes with elevation, latitude and longitude, and production rate of 3.92 ± 0.31 atoms/g·year for this LSDn scaling (see Borchers et al., 2016, Marrero et al., 2016 and Phillips et al., 2016 for details). In both cases, all the CRN model ages are calculated assuming no erosion, therefore all these models are minimum ages for that of the strath terraces.
The authors would like to apologise for any inconvenience caused.

Keywords: AMS; geomorphology

Permalink: https://www.hzdr.de/publications/Publ-31090
Publ.-Id: 31090


Effects of pillar size modulation on the magneto-structural coupling in self-assembled BiFeO3–CoFe2O4 heteroepitaxy

Amrillah, T.; Chen, Y.-X.; Ngoc Duong, M.; Abdussalam, W.; Mangasa Simanjuntak, F.; Chia-Hao, C.; Ying-Hao, C.; Jenh-Yih, J.

The magneto-structural coupling of BiFeO3 (BFO)–CoFe2O4 (CFO)/LaAlO3 (LAO) heteroepitaxy with various lateral sizes of CFO pillars embedded in a BFO matrix was investigated. A struc- tural phase transformation of the BFO matrix was observed when the pillar size of CFO was increased to exceed 200 nm. Such structural transformation led to modification of magneto-elastic coupling behavior and magnetic anisotropy in the BFO–CFO/LAO system. The flexibility of tuning the pillar size of CFO, and hence, the strain and interfacial effect on the multiferroic system have significant application implications in these functional oxide nanocomposites.

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Permalink: https://www.hzdr.de/publications/Publ-31089
Publ.-Id: 31089


Revealing the Role of Epithelial Mechanics and Macrophage Clearance during Pulmonary Epithelial Injury Recovery in the Presence of Carbon Nanotubes

Septiadi, D.; Abdussalam, W.; Rodriguez-Lorenzo, L.; Spuch-Calvar, M.; Bourquin, J.; Petri-Fink, A.; Rothen-Rutishauser, B.

Wound healing assays are extensively used to study tissue repair mechanisms; they are typically performed by means of physical (i.e., mechanical, electrical, or optical) detachment of the cells in order to create an open space in which live cells can lodge. Herein, an advanced system based on extensive photobleaching-induced apoptosis; providing a powerful tool to understand the repair response of lung epithelial tissue, consisting of a small injury area where apoptotic cells are still intact, is developed. Notably, the importance of epithelial mechanics and the presence of macrophages during the repair can be understood. The findings reveal that individual epithelial cells are able to clear the apoptotic cells by applying a pushing force, whilst macrophages actively phagocytose the dead cells to create an empty space. It is further shown that this repair mechanism is hampered when carbon nanotubes (CNTs) are introduced: formation of aberrant (i.e., thickening) F-actins, maturation of focal adhesion, and increase in traction force leading to retardation in cell migration are observed. The results provide a mechanistic view of how CNTs can interfere with lung repair.

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Permalink: https://www.hzdr.de/publications/Publ-31087
Publ.-Id: 31087


Two-photon retinal theranostics by adaptive compact laser source

Podlipec, R.; Mur, J.; Petelin, J.; Štrancar, J.; Petkovšek, R.

To avoid a devastating effect of eye vision impairment on the information flow from the eye to our brain, enormous effort is being put during the last decades into the development of more sensitive diagnostics and more efficient therapies of retinal tissue. While morphology can be impressively imaged by optical coherence tomography, molecular-associated pathology information can be provided almost exclusively by auto-fluorescence-based methods. Among the latter, the recently developed fluorescence lifetime imaging ophthalmoscopy (FLIO) has the potential to provide both structural information and interacting pictures at the same time. The requirements for FLIO laser sources are almost orthogonal to the laser sources used in phototherapy that is expected to follow up the FLIO diagnostics. To make theranostics more effective and cheaper, the complete system would need to couple at least the modalities of low-power high-repetition-rate FLIO and precision high-pulse energy-adjustable repetition rate phototherapy. In addition, the intermediate-power high repetition rate for two-photon excitation would also be desired to increase the depth resolution. In our work, compact fiber-laser based on high-speed gain-switched laser diode has been shown to achieve adaptable/independently tunable repetition rate and energy per pulse allowing coupled fluorescence lifetime diagnostics via two-photon excitation and phototherapy via laser-induced photodisruption on a local molecular environment in a complex ex vivo retinal tissue.

Keywords: adaptable fiber laser; retinal tissue; theranostics; multimodal imaging; fluorescence lifetime imaging

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  • Secondary publication expected from 11.05.2021

Permalink: https://www.hzdr.de/publications/Publ-31086
Publ.-Id: 31086


Material assignment for proton range prediction in Monte Carlo patient simulations using stopping-power datasets

Fibiani-Permatasari, F.; Eulitz, J.; Richter, C.; Wohlfahrt, P.; Lühr, A.

Motivation and objective: For each institute, the selection and calibration of the most suitable approach to assign material properties for Monte Carlo (MC) patient simulation in proton therapy is a major challenge. Current conventional approaches based on computed tomography (CT) depend on CT acquisition and reconstruction settings. This study proposes a material assignment approach, referred to as MATA (MATerial Assignment), which is independent of CT scanner properties and, therefore, universally applicable by any institute. Materials and methods: The MATA approach assigns material properties to the physical quantity stopping-power ratio (SPR) using a set of 40 material compositions specified for human tissues and linearly determined mass density. The application of clinically available CT-number-to-SPR conversion avoids the need for any further calibration. The MATA approach was validated with homogeneous and heterogeneous SPR datasets by assessing the SPR accuracy after material assignment obtained either based on dose scoring or determination of water-equivalent thickness. Finally, MATA was applied on patient datasets to evaluate dose differences induced by different approaches for material assignment and SPR prediction. Results: The deviation between the SPR after material assignment and the input SPR was close to zero in homogeneous datasets and below 0.002 (0.2% relative to water) in heterogeneous datasets, which was within the systematic uncertainty in SPR estimation. The comparison of different material assignment approaches revealed relevant differences in dose distribution and SPR. The comparison between two SPR prediction approaches, a standard look-up table and direct SPR determination from dual-energy CT, resulted in patient-specific mean proton range shifts between 1.3 mm and 4.8 mm. Conclusion: MATA eliminates the need for institution-specific adaptations of the material assignment. It allows for using any SPR dataset and thus facilitates the implementation of more accurate SPR prediction approaches. Hence, MATA provides a universal solution for patient modeling in MC-based proton treatment planning.

Keywords: Monte Carlo simulation; TOPAS; stopping-power ratio; dual-energy CT; proton radiotherapy

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  • Secondary publication expected from 11.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31085
Publ.-Id: 31085


Thermal neutron radiography of a passive proton exchange membrane fuel cell for portable hydrogen energy systems

M. Chaparro, A.; Ferreira-Aparicio, P.; Folgado, M. A.; Hübscher, R.; Lange, C.; Weber, N.

A proton exchange membrane fuel cell (PEMFC) for portable applications is studied with thermal neutron radiography. The PEMFC operates under passive conditions, with air-breathing cathode and dead-end anode supplied with static ambient air and dry hydrogen, respectively. A columnar cathodic plate favors the mobility of water drops over the cathode surface and their elimination. Thermal neutron images show liquid water build-up during operation of the cell in vertical and horizontal position, i.e. aligned parallel and perpendicular to the gravity field, respectively. Polarization curves and impedance spectroscopy show orientation dependent cell response that can be related with the water profiles. In vertical position, the elimination of drops sliding over the cathode surface as well as natural convection favor lower water contents in the cathode and improve oxygen transport. The vertical cell can be operated for hours in ambient conditions, providing steady power densities above 100 mW cm-² . In horizontal position, natural forces are less effective for water removal leading to 17% decrease in peak power density. The horizontal position is especially adverse if the upper electrode is the cathode, because anode flooding causes cell failure after production of a small amount of water (5 mg cm-²).

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  • Secondary publication expected from 06.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31084
Publ.-Id: 31084


Element- and orbital-selective magnetic coherent rotation at the first-order phase transition of a hard uniaxial ferrimagnet

Yamamoto, S.; Gorbunov, D.; Akai, H.; Yasumura, H.; Kotani, Y.; Nakamura, T.; Kato, T.; Mushnikov, N. V.; Andreev, A. V.; Nojiri, H.; Wosnitza, J.

3d-4 f intermetalic compounds with heavy rare-earth elements show first-order phase transitions in high magnetic fields due to the competition between the exchange interaction and the magnetocrystalline anisotropy. However, the microscopic picture of the field-induced noncollinear magnetic structures remains elusive. Here we report the direct experimental observation of the coherent stepwise rotation of the 3d and 4 f magnetic moments of the uniaxial hard ferrimagnet TmFe5Al7 by using soft x-ray magnetic circular dichroism in pulsed magnetic fields up to 25 T. The element- and shell-selective moments show a transition from the collinear ferrimagnet toward the forced ferromagnetic state via a canted phase, which is explained by a two-sublattice model.

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Permalink: https://www.hzdr.de/publications/Publ-31083
Publ.-Id: 31083


Advanced characterization of multicaloric materials in pulsed magnetic fields

Gottschall, T.; Bykov, E.; Gràcia-Condal, A.; Beckmann, B.; Taubel, A.; Pfeuffer, L.; Gutfleisch, O.; Manosa, L.; Planes, A.; Scurschii, I.; Wosnitza, J.

The multicaloric effect is described by a temperature or entropy change of a material triggered by external stimuli applied or removed simultaneously or sequentially. The prerequisite for this is a material exhibiting multiple ferroic states. However, direct measurements of the effect are rarely reported. Now, for this reason, we built a measurement device allowing to determine the adiabatic temperature change in pulsed magnetic fields and, simultaneously, under the influence of a uniaxial load. We selected the all-d-metal Heusler alloy Ni–Mn–Ti–Co for our first test because of its enhanced mechanical properties and enormous magneto- and elastocaloric effects. Ni–Mn–Ti–Co was exposed to pulsed magnetic fields up to 10 T and uniaxial stresses up to 80 MPa, and the corresponding adiabatic temperature changes were measured. With our new experimental tool, we are able to better understand multicaloric materials and determine their cross-coupling responses to different stimuli.

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Permalink: https://www.hzdr.de/publications/Publ-31082
Publ.-Id: 31082


Unexpected magnetic phase in the weakly ordered spin-1/2 chain cuprate Sr2CuO3

Sergeicheva, E. G.; Sosin, S. S.; Gorbunov, D.; Zherlitsyn, S.; Gu, G. D.; Zaliznyak, I. A.

The magnetic phase diagram of a spin- 1/2 chain antiferromagnet Sr2CuO3 is studied by an ultrasound phase-sensitive detection technique. The system is in the extreme proximity of the Luttinger-liquid quantum-critical point and we observe an unusually strong effect of magnetic field, which is very weak compared to the in-chain interaction, on the Néel ordering temperature. Inside the ordered phase, we detect an unexpected, field-induced continuous phase transition. The transition is accompanied by softening of magnetic excitation observed by electron-spin resonance, which in previous work [E. G. Sergeicheva et al., Phys. Rev. B 95, 020411(R) (2017)] was associated with a longitudinal (amplitude) mode of the order parameter. These results suggest a transition from a transverse collinear antiferromagnet to an amplitude-modulated spin-density-wave phase in a very weak magnetic field, which is unexpected for a system of weakly coupled Heisenberg spin- 1/2 chains.

Permalink: https://www.hzdr.de/publications/Publ-31081
Publ.-Id: 31081


Effect of curvature on the eigenstates of magnetic skyrmions

Korniienko, A.; Kakay, A.; Sheka, D. D.; Kravchuk, V. P.

Spectrum of spin eigenmodes localized on a ferromagnetic skyrmion pinned by a geometrical defect (bump) of magnetic films is studied theoretically. By means of direct numerical solution of the corresponding eigenvalue problem and finite element micromagnetic simulations we demonstrate, that the curvature can induce localized modes with higher azimuthal and radial quantum numbers, which are absent for planar skyrmions (for the same parameters). The eigenfrequencies of all modes, except the breathing and gyromodes decreases with increasing curvature. Due to the translational symmetry break, the zero translational mode of the skyrmion gains a finite frequency and forms the gyromode, which describes the uniform rotation of skyrmions around the equilibrium position. In order to treat the gyromotion analytically we developed a Thiele-like collective variable approach. We show that Neel skyrmions in curvilinear films experience a driving force originating from the gradient of the mean curvature. The gyrofrequency of the pinned skyrmion is proportional to the second derivative of the mean curvature at the point of equilibrium.

Keywords: skyrmions; curvature; eigenmodes; Thiele equation

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Permalink: https://www.hzdr.de/publications/Publ-31080
Publ.-Id: 31080


Multidimensional characterization of separation processes – Part 2: Comparability of separation efficiency

Buchmann, M.; Schach, E.; Leißner, T.; Kern, M.; Mütze, T.; Rudolph, M.; Peuker, U.; Tolosana Delgado, R.

Following the proposal of deriving statistical entropy maps from multidimensional separation curves, an extension is proposed to allow to compare the separation efficiency of various separation processes. This is achieved by integrating the entropy map weighted by the mass distribution of the particles in the feed. This proposal has several advantages: its straightforward extension to multidimensional partition curves, its scalar value (which allows for a natural ranking of processes), its flexibility to adapt to each and every feed, and its non-parametric character. A typical dynamic air classification process of an iron ore is presented as an example.

Keywords: Multidimensional partition curves; Weighted entropy; Particle tracking; Kernel density estimates; Mineral processing

Permalink: https://www.hzdr.de/publications/Publ-31079
Publ.-Id: 31079


Generating a tide-like flow in a cylindrical vessel by electromagnetic forcing

Jüstel, P.; Röhrborn, S.; Frick, P.; Galindo, V.; Gundrum, T.; Schindler, F.; Stefani, F.; Stepanov, R.; Vogt, T.

We show and compare numerical and experimental results on the electromagnetic generation of a tide-like flow structure in a cylindrical vessel which is filled with the eutectic liquid metal alloy GaInSn. Fields of various strengths and frequencies are applied to drive liquid metal flows. The impact of the field variations on amplitude and structure of the flows are investigated. The results represent the basis for a future Rayleigh-Bénard experiment, in which a modulated tide-like flow perturbation is expected to synchronize the typical sloshing mode of the large-scale circulation. A similar entrainment mechanism for the helicity in the Sun may be responsible for the synchronization of the solar dynamo with the alignment cycle of the tidally dominant planets Venus, Earth and Jupiter.

Keywords: electromagnetic forcing; impinging jets; magnetohydrodynamics; helicity synchronization

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Permalink: https://www.hzdr.de/publications/Publ-31078
Publ.-Id: 31078


Magnetic Effects on Microstructure and Solute Plume Dynamics of Directionally Solidifying Ga-In Alloy

Kao, A.; Shevchenko, N.; He, S.; Lee, P. D.; Eckert, S.; Pericleous, K.

The effects of applying a 0.2 T transverse magnetic field to a solidifying Ga-25%wt.In alloy were investigated through a joint experimental and numerical study. The magnetic field introduced significant changes to both the microstructure and the dynamics of escaping high concentration Ga plumes. Plume migration across the interface was quantified and correlated to simulations to demonstrate that Thermoelectric Magnetohydrodynamics (TEMHD) is the underlying mechanism. TEMHD introduced macro segregation within the dendritic structure leading to the formation of a stable ‘chimney’ channel by increasing solutal buoyancy in the flow direction. The resulting pressure difference across the solidification front, introduced a secondary hydrodynamic phenomenon that subsequently causes solute plume migration.

Keywords: Microstructure; Solidification; Magnetic Field; Freckle Defects; X-ray imaging; In situ observations

Permalink: https://www.hzdr.de/publications/Publ-31077
Publ.-Id: 31077


Silicon Surface Passivation by ALD-Ga₂O₃: Thermal vs. Plasma-Enhanced Atomic Layer Deposition

Hiller, D.; Julin, J. A.; Chnani, A.; Strehle, S.

Silicon surface passivation by gallium oxide (Ga2O3) thin films deposited by thermal- and plasma-enhanced atomic layer deposition (ALD) over a broad temperature range from 75 °C to 350 °C is investigated. In addition, the role of oxidant (O3 or O-plasma) pulse lengths insufficient for saturated ALD-growth is studied. The material properties are analyzed including the quantification of the incorporated hydrogen. We find that oxidant dose pulses insufficient for saturation provide for both ALD methods generally better surface passivation. Furthermore, different Si surface pretreatments are compared (HF-last, chemically grown oxide, and thermal tunnel oxide). In contrast to previous reports, the annealing time to activate the surface passivation is found to be significantly shorter. The best surface saturation current densities (JOs) or surface recombination velocities (Seff) are 6 and 9 fA/cm² or 0.6 and 1.5 cm/s for n- and p-type Si, respectively. We correlate the surface passivation with the negative fixed charge density (Qfix; field-effect passivation) and the interface defect density (Dit; chemical passivation). It turns out that a high Qfix is present, irrespective of the utilized ALD-method, deposition temperature, or postannealing, whereas low Dit is only achieved fo rplasma-enhanced ALD at low temperatures. A critical H-density of∼10¹⁶ cm−2 is identified as a necessary but not sufficient condition for excellent surface passivation. Finally, contact resistivities are measured to investigate the possibility of using ALD-Ga2O3 as passivating contact material. In order to understand the current-voltage measurements, the energetic positions of the band edges and the Fermi level are determined by ultraviolet photoelectron spectroscopy and Kelvin probe.

Keywords: Atomic layer deposition (ALD); gallium oxide(Ga2O3); hydrogen; silicon surface passivation

Permalink: https://www.hzdr.de/publications/Publ-31076
Publ.-Id: 31076


The integration of structural mechanics into microstructure solidification modelling

Soar, P.; Kao, A.; Djambazov, G.; Shevchenko, N.; Eckert, S.; Pericleous, K.

In situ structural mechanics are an often neglected area when modelling alloy microstructure during solidification, despite the existence of practical examples and studies which seem to indicate that the interaction between thermal or mechanical stresses and microstructure can have a significant impact on its evolution and hence the final properties at a macroscopic level. A bespoke structural mechanics solver using the finite volume method has been developed to solve the linear elasticity equations, with design choices being made to facilitate the coupling of this solver to run in situ with an existing solidification model. The accuracy of the structural mechanics solver is verified against an analytic solution and initial results from a fully coupled system are presented which demonstrate in a fundamental example that the interaction between structural mechanics and a solidifying dendrite can lead to a significant change in growth behaviour.

Keywords: Structural Mechanics; Microstrcture Solidification; Multi-Physics

  • Lecture (Conference) (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden
  • Open Access Logo IOP Conference Series: Materials Science and Engineering 861(2020)1, 012054
    DOI: 10.1088/1757-899X/861/1/012054

Permalink: https://www.hzdr.de/publications/Publ-31075
Publ.-Id: 31075


Controlling Freckle Defect Formation with Magnetic Fields During Directional Solidification of GaIn Alloy

Kao, A.; Krastins, I.; Shevchenko, N.; Eckert, S.; Pericleous, K.

Segregation of alloying components during solidification leads to stable solute channels, that solidify into defects called freckles. Freckles are caused by buoyancy driving lighter liquid elements, forming a macroscale channel that is fed by inter-dendritic flow. When fully solidified this channel represents a discontinuity in material properties and can lead to the failure of components. The application of a magnetic field, B, adds two physical phenomena to the process: the first is Electromagnetic Damping (EMD) of the liquid metal motion, the second is interstitial flow due to Thermoelectric (TE) Magnetohydrodynamics (MHD). TE effects translate temperature variations at the junction of two conductive materials into electric current, in this case between the solid and liquid.
The current, j¸ interacts with the magnetic field producing a Lorentz force F=j×B. Both the orientation and magnitude of the magnetic field determine the direction and strength of EMD and TEMHD effects.
Consider directional solidification of a solutal unstable buoyant alloy, namely Ga-25wt. %In. Both high velocity plumes of solute and the TE currents will be predominantly aligned to the thermal gradient (∇T), while the feeding inter-dendritic flow is primarily perpendicular to ∇T. A magnetic field orientated perpendicular to ∇T introduces EMD effects on the channel and also interacts with TE currents driving TEMHD flow. To capture these phenomena a parallel Cellular Automata Lattice Boltzmann Method that solves for microstructure solidification, fluid dynamics and electromagnetism using 100s millions of computational cells is used to simulate the freckle formation process at the sample scale. The results indicate that the channel formation can be significantly altered, showing the magnetic field as a potential technique for defect mitigation.

Keywords: Microstructure Solidification; Magnetic Field; Freckle Defects

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden

Permalink: https://www.hzdr.de/publications/Publ-31074
Publ.-Id: 31074


Volt-per-Ångstrom terahertz fields from X-ray free-electron lasers

Tanikawa, T.; Karabekyan, S.; Kovalev, S.; Casalbuoni, S.; Askegar, V.; Bonetti, S.; Wall, S.; Laarmann, T.; Turchinovich, D.; Zalden, P.; Kampfrath, T.; Fisher, A. S.; Stojanovic, N.; Gensch, M.; Geloni, G.

The electron linear accelerators driving modern X-ray free-electron lasers can emit intense, tunable, quasi-monochromatic terahertz (THz) transients with peak electric fields of V Å−1 and peak magnetic fields in excess of 10 T when a purpose-built, compact, superconducting THz undulator is implemented. New research avenues such as X-ray movies of THz-driven mode-selective chemistry come into reach by making dual use of the ultra-short GeV electron bunches, possible by a rather minor extension of the infrastructure.

Keywords: superradiant emission; terahertz control; terahertz radiation; ultrafast phenomena; X-ray free-electron laser

Permalink: https://www.hzdr.de/publications/Publ-31073
Publ.-Id: 31073


In situ observation of directional solidification in Ga-In alloy under a transverse DC magnetic field

He, S.; Shevchenko, N.; Eckert, S.

The directional solidification of a Ga-25wt.%In alloy under the effect of a transverse DC magnetic field is investigated by X-ray radiography. The magnetic field pointing parallel to the X-ray beam is generated by two ring-shaped permanent magnets. The magnetic field reaches values up to ~0.19 T in the field of view. The dendritic growth and the flow patterns of Ga-rich plumes migrating along the solidification front are captured and analyzed. It shows that the local fluctuations of solute concentration are partially damped by the magnetic field. At the temperature gradient of 1 K/mm, the growth velocities of solidification front and plumes are not affected. In the case of higher temperature gradient (~2 K/mm), the magnetic field causes an increase of the plume velocity in the horizontal direction and a decrease in the vertical direction while the velocity of the solidification front remains constant. Additionally, it is found that the magnetic field damps the fluctuations of tip velocity and refines the primary arm spacing. Above phenomena are discussed based on the thermoelectric magnetic and electromagnetic braking effects. The in situ experimental data are important for verification and improvement of the existing numerical simulations of solidification under the magnetic field.

Keywords: X-ray radiography; directional solidification; transverse magnetic field; dendritic growth; Ga-rich plumes

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden
  • Open Access Logo IOP Conference Series: Materials Science and Engineering 861(2020)1, 012025
    DOI: 10.1088/1757-899X/861/1/012025

Permalink: https://www.hzdr.de/publications/Publ-31072
Publ.-Id: 31072


Evolution of dendritic morphology in a solidifying Ga-In alloy studied by in-situ synchrotron radiography

Shevchenko, N.; Neumann-Heyme, H.; Grenzer, J.; Keplinger, O.; Rack, A.; Eckert, K.; Eckert, S.

The local dynamics of dendritic tips and side arms during the growth and coarsening stages are studied by X-ray synchrotron radiography and by numerical simulation. The direct investigation of dendritic side arm evolution appears to be rather complex and impose high requirements with respect to the spatial and temporal resolution and sensitivity of the detector. The synchrotron imaging experiments were performed at the ID19 beamline (ESRF, France) at a spatial resolution of < 1 µm. A flat sample of a Ga-In alloy is solidified from top to down applying a vertical temperature gradient. The present measurements provide real-time in-situ data on three phenomena that are of major importance in dendrite morphology evolution: side arm coarsening, side arm-splitting and dendrite tip evolution. The combination of numerical modeling and synchrotron experiments has allowed to improve the understanding of coarsening of dendritic side arms and to obtain material information that is relevant for quantitative modeling. Another interesting effect can be observed during in situ solidification experiments: a transition from a four-fold symmetry to a hyperbranched dendritic morphology. This morphological transition originating from the splitting of dendrite side arms has been detected.

Keywords: X-ray radiography; synchrotron experiments; side arms; dendrite tip; coarsening

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden

Permalink: https://www.hzdr.de/publications/Publ-31071
Publ.-Id: 31071


Para-ferroelectric phase transition driven by swift heavy-ion irradiation in KTN crystal

He, S.; Yang, Q.; Li, X.; Liu, H.; Cao, L.; Akhmadaliev, S.; Wang, X.; Ren, Y.; Zhou, S.; Wu, P.

We report a novel approach of using swift O5+ ion irradiation to implement para-ferroelectric phase transition in a relaxor ferroelectric KTa0.62Nb0.38O3 (KTN) single crystal. With 15-MeV swift O5+ ion irradiation, a well-defined two-layer structure has been formed in the KTN sample due to the interaction between the O ions and KTN via electronic stopping and the nuclear stopping, respectively. The microstructures in these two layers are characterized by using a micro-Raman (μ-Raman) spectral technique. The significant changes of both spectral intensities and locations in three characteristic Raman peaks suggest that the top layer of the KTN sample due to electronic stopping exists a single-domain-ferroelectric state with a uniform and enhanced polarization orientation along [0 0 1]c direction. More importantly, we observe the irradiated region can effectively confine the light propagation in the ferroelectric layer, which can be further controlled by external fields. The results are promising for designing new integrated photonic devices.

Keywords: Phase transition; Swift heavy ion irradiation; Relaxor ferroeletrics

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  • Secondary publication expected from 08.04.2021

Permalink: https://www.hzdr.de/publications/Publ-31070
Publ.-Id: 31070


Tailoring Magnetic Features in Zigzag-Edged Nanographenes by Controlled Diels–Alder Reactions

Ajayakumar, M.; Fu, Y.; Liu, F.; Komber, H.; Tkachova, V.; Xu, C.; Zhou, S.; Popov, A.; Liu, J.; Feng, X.

Nanographenes (NGs) with tunable electronic and magnetic properties have attracted enormous attention in the realm of carbon-based nanoelectronics. In particular, NGs with biradical character at the ground state are promising building units for molecular spintronics. However, most of the biradicaloids are susceptible to oxidation under ambient conditions and photolytic degradation, which hamper their further applications. Herein, we demonstrated the feasibility of tuning the magnetic properties of zigzag-edged NGs in order to enhance their stability via the controlled Diels–Alder reactions of peri-tetracene (4-PA). The unstable 4-PA (y0=0.72; half-life, t1/2=3 h) was transformed into the unprecedented benzo-peri-tetracenes (BPTs) by a one-side Diels–Alder reaction, which featured a biradical character at the ground state (y0=0.60) and exhibited remarkable stability under ambient conditions for several months. In addition, the fully zigzag-edged circumanthracenes (CAs) were achieved by two-fold or stepwise Diels–Alder reactions of 4-PA, in which the magnetic properties could be controlled by employing the corresponding dienophiles. Our work reported herein opens avenues for the synthesis of novel zigzag-edged NGs with tailor-made magnetic properties.

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Permalink: https://www.hzdr.de/publications/Publ-31068
Publ.-Id: 31068


Separation of aluminium and iron from lanthanum - a comparative study of solvent extraction and hydrolysis-precipitation

Balinski, A.; Kelly, N.; Helbig, T.; Meskers, C. E. M.; Reuter, M.

This study investigates the removal of aluminium and iron from REE containing solutions by solvent extraction with saponified naphthenic acid and by hydrolysis-precipitation. The results emphasize both, the preferential application as well as limitations of every method. We find that emulsification occurring during solvent extraction of aluminium is caused by its slow extraction rate in comparison to the neutralization reaction and by the proximity of the pH value required for aluminium extraction and the pH value at which hydrolysis of aluminium occurs. However, by choosing long shaking time of at least 4 h the emulsion recedes. The formation of emulsion can be avoided by strict control of pH value during the extraction. Moreover, the loading capacity of the organic phase with aluminium is limited due to the strong increase in viscosity of the organic phase with increasing aluminium concentration and due to the gel formation. Regarding the extraction of iron, the amount of extracted ions is limited due to the overlap of the pH range required for the extraction with pH range in which sparingly soluble iron oxides/hydroxides are formed. In summary, aluminium and iron can be simultaneously removed from REE containing solution by solvent extraction with saponified naphthenic acid in one extraction stage only from diluted solutions. However, in comparison to the hydrolysis-precipitation method a higher purity of the solution is achieved. A complete removal of aluminium and iron from concentrated solutions can be achieved in two stages. First, the content of aluminium and iron should be reduced by hydrolysis-precipitation. After that, a high-purity solution can be obtained by subsequent solvent extraction by saponified naphthenic acid.

Keywords: rare earth elements; aluminium; iron; impurity removal; solvent extraction; naphthenic acid; saponification; hydrolysis-precipitation

Permalink: https://www.hzdr.de/publications/Publ-31067
Publ.-Id: 31067


openTIV

Ziegenhein, T.; Heßenkemper, H.; Lucas, D.

openTIV is a computer vision library mainly developed to evaluate pictures taken from multiphase flows. Specifically, the application of identifying phase interfaces and tracking particles (PTV and PIV) was intended by the authors. Besides that, post-processing libraries to calculate, for example, the standard dimensionless numbers (Reynolds, Morton, Eoetvoes (Bond), etc.) and void fraction profiles are provided as well. All libraries are based on the standard mathematical and physical library, which consists of essential solvers and mathematical structures, inside the package. The library includes the tools to help develop new methods for evaluating images from multiphase flows. It is not intended to provide a complete package of image processing methods, as can be found in the OpenCV package (which can be used with the openTIV libraries).

Keywords: Computer Vision; Multiphase Flow; PIV; PTV; Boundary Tracking; Image Processing

Permalink: https://www.hzdr.de/publications/Publ-31066
Publ.-Id: 31066


Structural Evolution of Ag-LEV Zeolite upon Heating: an in situ Single-Crystal X-ray Diffraction (SC-XRD) and X-ray Absorption Spectroscopy (XAS) Study

Cametti, G.; Scheinost, A.; Churakov, S. V.

Ag-modified zeolites are of great interest because of their improved catalytic, photocatalytic, sorption, and antibacterial properties []. To properly tune these properties, a deeper understanding of several structural factors is necessary. In particular, the following aspects have been proved to play a key role[]: i) the position of silver atoms with respect to the tetrahedral framework, ii) the possible formation of Ag-clusters within the zeolitic pores, and iii) the structural changes occurring upon dehydration, since most of these materials are employed after thermal treatment.

Keywords: zeolite; silver; XAFS; XRD; atomistic simulations; DFT

Permalink: https://www.hzdr.de/publications/Publ-31065
Publ.-Id: 31065


Stereotactic ablative body radiotherapy (SABR) combined with Immunotherapy (L19-IL2) in stage IV NSCLC patients, ImmunoSABR: a multicentre, randomised controlled open-label phase II trial

Lieverse, R.; Van, L. E.; Oberije, C.; Troost, E. G. C.; Hadrup, S.; Dingemans, A.; Hendriks, L.; Eckert, F.; Hiley, C.; Dooms, C.; Lievens, Y.; De, J. M.; Hendriks, L.; Bussink, J.; Geets, X.; Valentini, V.; Elia, G.; Nerio, D.; Billiet, C.; Abdollahi, A.; Pasquier, D.; Boisselier, P.; Yaromina, A.; De, R. D.; Dubois, L.; Lambin, P.

About 50% of non-small cell lung cancer (NSCLC) patients have metastatic disease at initial diagnosis, which limits their treatment options and, consequently, the 5-year survival rate (15%). Immune checkpoint inhibitors (ICI), either alone or in combination with chemotherapy, have become standard of care (SOC) for most good performance status patients. However, most patients will not obtain long-term benefit, and new treatment strategies are therefore still needed. We previously demonstrated clinical safety of the tumour-selective immunocytokine L19-IL2, consisting of the anti-EDB scFv L19 antibody coupled to IL2, combined with stereotactic ablative radiotherapy (SABR). Within this phase II ImmunoSABR trial, the combination of SABR with or without ICI and the immunocytokine L19-IL2 will be tested as 1st, 2nd or 3rd line treatment in stage IV NSCLC patients. This bi-modal and triple treatment approach is based on the direct cytotoxic effect of radiotherapy, the tumour selective immunocytokine L19-IL2, the abscopal effect observed distant from the irradiated metastatic site(s), and the memory effect.
This investigator initiated, multicentric, randomised controlled open-label phase II clinical trial (NCT03705403) will test the hypothesis that the combination of SABR and L19-IL2 increases the progression free survival (PFS) in patients with limited metastatic NSCLC. Patients will be stratified according to their metastatic load (oligo-metastatic: up to 5, or poly-metastatic: 6 to 10 metastases). Patients will be randomised by minimisation to the experimental (E-arm) or the control arm (C-arm). The C-arm will receive SOC, according to the local protocol. E-arm oligo-metastatic patients will receive SABR to all lesions followed by L19-IL2 therapy; radiotherapy for poly-metastatic patients consists of irradiation of at least one (symptomatic) to a maximum of 5 lesions (including ICI in both arms if this is the SOC). ImmunoSABR consists of 14 participating centres located in 6 countries. The accrual period will be 2.5 years, starting after the first centre is initiated and active. Primary endpoint is PFS at 1.5 years based on blinded radiological review, and secondary endpoints are overall survival, toxicity, quality of life and abscopal response. Associative biomarker studies, blood and tumour cell immune monitoring, CT-based radiomics, stool collection, iRECIST, and tumour growth rate will be performed. The first results are expected end 2023.

Keywords: Immunotherapy; L19-IL2; anti-PDL1; anti-PD1; radiotherapy; SABR; phase 2; NSCLC; stage IV; multicentre

  • Open Access Logo BMC Cancer 20(2020), 557

Permalink: https://www.hzdr.de/publications/Publ-31064
Publ.-Id: 31064


National societies' needs as assessed by the ESTRO National Society Committee survey: a European perspective

Garibaldi, C.; Jornet, N.; Tan, L.; Bojen, A.; Franco, P.; Bussink, J.; Troost, E. G. C.; Bak, B.; Bibault, J.; Dzhugashvili, M.; Van, D. B. L.; Fizaine, L.; Leci, A.; Ricardi, U.; Jereczek-Fossa, B.

Purpose: to determine how ESTRO can collaborate with Radiation Oncology National Societies (NS) according to its mission and values, and to define the new roadmap to strengthen the NS network role in the forthcoming years.

Materials and methods: the ESTRO NS committee launched a survey addressed to all European National Societies, available online from June 5th to October 30th 2018. Questions were divided into three main sections: 1. general information about NS; 2. relevant activities (to understand the landscape of each NS context of action); 3. relevant needs (to understand how ESTRO can support the NS). Eighty-nine European NS were invited to participate. Respondents were asked to rank ESTRO milestones in order of importance, indicating the level of priority to their society.

Results: a total of 64 out of 89 NS (72%) from 32 European countries completed the questionnaire. The majority of NS ranked “Optimal patient care to cure cancer and to reduce treatment-related toxicity” as the highest level of priority. This aligns well with the ESTRO vision 2030 “Optimal health for all together.” NS also indicated a high need for more consensus guidelines and exchange of best practices, access to high quality accredited education, implementation of the ESTRO School Core Curriculum at the national level, and defining quality indicators and standard in Radiation Oncology, improved communication and increased channelling of information.

Conclusion: The results of this survey will be used to strengthen the relations between ESTRO and European NS to promote and develop initiatives to improve cancer care.

Permalink: https://www.hzdr.de/publications/Publ-31063
Publ.-Id: 31063


Molecular imaging of monocarboxylate transporters with PET – development and biological evaluation of novel 2-fluoropyridinyl analogs of FACH

Sadeghzadeh, M.; Deuther-Conrad, W.; Wenzel, B.; Gündel, D.; Toussaint, M.; Moldovan, R.-P.; Fischer, S.; Ludwig, F.-A.; Teodoro, R.; Jonnalagadda, Shirisha; Jonnalagadda, Sravan K.; Mereddy, Venkatram R.; Drewes, Lester R.; Brust, P.

Introduction
Monocarboxylate transporters 1-4 (MCT1-4) are involved in several metabolism-related diseases, especially cancer, providing the chance to be considered as relevant targets for diagnosis and therapy. Recently, we reported on [18F]FACH as a novel MCT-targeting imaging agent (1), whose limited blood-brain barrier permeability, however, excludes application in brain diseases. Accordingly, we aimed to develop a more lipophilic FACH-derived radiotracer possessing higher brain uptake.
Materials and Methods
Two 2-fluoropyridinyl-substituted analogs of FACH (1 and 2) were obtained by Buchwald-Hartwig cross coupling reaction.
The potency of 1 and 2 to inhibit MCT1 was measured by [14C]lactate uptake assay using rat brain endothelial-4 cells. Radiolabeling of [18F]1 was proceeded using 1 mg nitro precursor and [18F]fluoride in the presence of Kryptofix and K2CO3 in dimethyl sulfoxide at 130 °C within 15 min. The logD7.4 value of [18F]1 was experimentally determined in the n-octanol-PBS system. For biological evaluation of [18F]1, in vitro autoradiography on cryosections of mouse kidney and small animal PET-MRI studies in female CD-1 mice were performed. Target specificity was proven by using the sodium salt of the MCT inhibitor α-cyano-4-hydroxycinnamic acid (α-CCA-Na).

Results
The analogs 1 and 2 inhibited MCT1 with IC50 values of 118 and 274 nM, respectively. [18F]1 was obtained by radiofluorination of the nitro precursor via nucleophilic aromatic substitution reaction with radiochemical yields of 73 ± 12% (n = 4, non-isolated, radio-HPLC), a high radiochemical purity of ˃ 98% and molar activities in the range of 180-200 GBq/µmol (n = 3, end of synthesis) using starting activities of 2-3 GBq. The logD7.4 value of 0.82 achieved for [18F]1 indicated 2-fold higher lipophilicity in comparison to [18F]FACH (2). In vivo and in vitro studies revealed high uptake of the new radiotracer in kidney and other peripheral MCT-expressing organs together with significant reduction by using α-CCA-Na (10 µM). The brain uptake of [18F]1 was similar to [18F]FACH without significant washout and an almost unchanged SUV of 0.15 between 15 and 60 min p.i.
Conclusion
Despite a higher lipophilicity of [18F]1 compared to [18F]FACH, the brain uptake of [18F]1 was in a similar low range, revealing the need for further structural modification. However, a high and specific uptake of the new radiotracer in the kidneys suggests suitability of [18F]1 for investigations on the expression of MCT in vivo.
References
(1) Sadeghzadeh M, et al. J Label Compd Radiopharm.2019; 62: 411-424.
(2) Sadeghzadeh M, et al. Sci Rep. 2019; 9: 18890-18897.

  • Contribution to proceedings
    33rd Annual Congress of the European Association of Nuclear Medicine (EANM-2020), 17.-21.10.2020, Vienna, Austria
    European Journal of Nuclear Medicine and Molecular Imaging 47(2020), S11-S12

Permalink: https://www.hzdr.de/publications/Publ-31062
Publ.-Id: 31062


OpenFOAM activities at HZDR

Schlegel, F.

Introcution into the OpenFOAM activties at HZDR

  • Lecture (Conference)
    German CFD Network of Competence, 10.-11.03.2020, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31061
Publ.-Id: 31061


Identification of Dy³⁺ /Dy²⁺ as electron trap in persistent phosphors

Joos, J. J.; Korthout, K.; Amidani, L.; Glatzel, P.; Poelman, D.; Smet, P. F.

A long-standing issue in persistent luminescence is settled by providing direct evidence that Dy³⁺ is the main electron trap in Sr₄Al₁₄O₂₅:Eu,Dy by combining laser excitation with X-ray spectroscopy. A reversible electron transfer is demonstrated, controlled by light and showing the same kinetics as the persistent luminescence. Exposure to violet light induces charging by oxidation of the excited Eu²⁺ while Dy³⁺ is simultaneously reduced. Oppositely, detrapping of Dy²⁺ occurs at ambient temperature or by infrared illumination, yielding afterglow or optically stimulated luminescence, respectively.

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Permalink: https://www.hzdr.de/publications/Publ-31060
Publ.-Id: 31060


Visualization of Liquid Reaction in Submerged Top-blow Agitation Process

Zhang, X.; Wu, J.; Zhang, H.; Ding, W.; Zhang, J.

The liquid reaction in a submerged top-blow agitation process was studied using planar laser-induced fluorescence (PLIF) technology based on the principle of fluorescence quenching. The liquid reaction effects were analyzed using the reaction degree θ(t) and reaction time t95 under different conditions. The results show that the liquid reaction time decreases obviously for an increase in the air flow rate and submerged depth of the spray gun. The injection position of Fe3+ has a great influence on the reaction process; the reaction process is also different under other blowing conditions when Fe3+ is injected at the bottom. The reaction time of Fe3+ at the bottom injection position is higher than that at the top injection position; increasing the air flow rate and submerged depth of the spray gun can effectively reduce the difference in the reaction times at the two injection points. The effect of the injection position on the reaction time is eliminated when the spray gun submerged depth is close to the reactor bottom. The initial volume of Fe3+ has no obvious effect on the reaction time; however, an increase in the initial molarity of Fe3+ can decrease the reaction time.

Keywords: Fluorescence quenching reaction; Liquid reaction process; Planar laser-induced fluorescence; Reaction degree; Submerged top blow

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  • Secondary publication expected from 21.05.2021

Permalink: https://www.hzdr.de/publications/Publ-31059
Publ.-Id: 31059


Nonlocal stimulation of three-magnon splitting in a magnetic vortex

Körber, L.; Schultheiß, K.; Hula, T.; Verba, R.; Faßbender, J.; Kakay, A.; Schultheiß, H.

We present a combined numerical, theoretical and experimental study on stimulated three-magnon splitting in a magnetic disk in the vortex equilibrium state. Our micromagnetic simulations and Brillouin-light-scattering results confirm that three-magnon splitting can be triggered even below threshold by exciting one of the secondary modes by magnons propagating in a waveguide next to the disk. The experiments show that stimulation is possible over an extended range of excitation powers and a wide range of frequencies around the eigenfrequencies of the secondary modes. Rate-equation calculations predict an instantaneous response to stimulation and the possibility to prematurely trigger three-magnon splitting even above threshold in a sustainable manner. These predictions are confirmed experimentally using time-resolved Brillouin-light-scattering measurements and are in a good qualitative agreement with the theoretical results. We believe that the controllable mechanism of stimulated three-magnon splitting could provide a possibility to utilize magnon-based nonlinear networks as hardware for reservoir or neuromorphic computing.

Keywords: spin wave; nonlinear; three-magnon splitting; stimulation; micromagnetic simulation; BLS

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Permalink: https://www.hzdr.de/publications/Publ-31058
Publ.-Id: 31058


Metabolomics, machine learning and immunohistochemistry to predict succinate dehydrogenase mutational status in phaeochromocytomas and paragangliomas

Wallace, P. W.; Conrad, C.; Brückmann, S.; Pang, Y.; Caleiras, E.; Murakami, M.; Korpershoek, E.; Zhuang, Z.; Rapizzi, E.; Kroiss, M.; Gudziol, V.; Timmers, H. J. L. M.; Mannelli, M.; Pietzsch, J.; Beuschlein, F.; Pacak, K.; Robledo, M.; Klink, B.; Peitzsch, M.; Gill, A. J.; Tischler, A. S.; de Krijger, R. R.; Papathomas, T.; Aust, D.; Eisenhofer, G.; Richter, S.

Phaeochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumours with a hereditary background in over one third of patients. Mutations in succinate dehydrogenase (SDH) genes increase the risk for PPGLs and several other tumours. Mutations in subunit B (SDHB) in particular are a risk factor for metastatic disease, further highlighting the importance of identifying SDH mutations for patient management. Genetic variants of unknown significance, where implications for the patient and family members are unclear, are a problem for interpretation. For such cases, reliable methods for evaluating protein functionality are required. Immunohistochemistry for SDHB (SDHB-IHC) is the method of choice, but does not assess functionality at the enzymatic level. Liquid chromatography mass spectrometry-based measurements of metabolite precursors and products of enzymatic reactions provides an alternative method. Here, we compare SDHB-IHC with metabolite profiling in 189 tumours from 187 PPGL patients. Besides evaluating succinate:fumarate ratios (SFR), machine learning algorithms were developed to establish predictive models for interpreting metabolite data. Metabolite profiling showed higher diagnostic specificity compared to SDHB-IHC (99.2% vs 92.5%, p=0.021), whereas sensitivity was comparable. Application of machine learning algorithms to metabolite profiles improved predictive ability over that of the SFR, in particular for hard-to-interpret cases of head and neck paragangliomas (AUC 0.9821 vs. 0.9613, p=0.044). Importantly, the combination of metabolite profiling with SDHB-IHC has complementary utility, as SDHB-IHC correctly classified all but one of the false-negatives from metabolite profiling strategies while metabolite profiling correctly classified all but one of the false-negatives/positives from SDHB-IHC. From 186 tumours with confirmed status of SDHx variant pathogenicity, the combination of the two methods resulted in 185 correct predictions, highlighting the benefits of both strategies for patient management.

Keywords: mass spectrometry; succinate to fumarate ratio; multi-observer; Krebs cycle metabolites; linear discriminant analysis; LC-MS/MS; diagnostics; variants of unknown significance; metabolite profiling; prediction models

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  • Secondary publication expected from 01.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31057
Publ.-Id: 31057


Deuteration versus ethylation – strategies to improve the metabolic fate of a 18F-labeled celecoxib derivative

Laube, M.; Gassner, C.; Neuber, C.; Wodtke, R.; Ullrich, M.; Haase-Kohn, C.; Löser, R.; Köckerling, M.; Kopka, K.; Knieß, T.; Hey-Hawkins, E.; Pietzsch, J.

The inducible isoenzyme cyclooxygenase-2 (COX-2) is closely associated with chemo-/radioresistance and poor prognosis of solid tumors. Therefore, COX-2 represents an attractive target for functional characterization of tumors by positron emission tomography (PET). In this study, the celecoxib derivative 3-([18F]fluoromethyl)-1-[4-(methylsulfonyl)phenyl]-5-(p-tolyl)-1H-pyrazole ([18F]5a) was chosen as a lead compound having a reported high COX-2 inhibitory potency and a potentially low carbonic anhydrase binding tendency. The respective deuterated analog [D2,18F]5a and the fluoroethyl-substituted derivative [18F]5b were selected to study the influence of these modifications with respect to COX inhibition potency in vitro and metabolic stability of the radiolabeled tracers in vivo. COX-2 inhibitory potency was found to be influenced by elongation of the side chain but, as expected, not by deuteration. An automated radiosynthesis comprising 18F-fluorination and purification under comparable conditions provided the radiotracers [18F]5a,b and [D2,18F]5a in good radiochemical yields (RCY) and high radiochemical purity (RCP). Biodistribution and PET studies comparing all three compounds revealed bone accumulation of 18F-activity to be lowest for the ethyl derivative [18F]5b. However, the deuterated analog [D2,18F]5a turned out to be the most stable compound of the three derivatives studied here. Time-dependent degradation of [18F]5a,b and [D2,18F]5a after incubation in murine liver microsomes was in accordance with the data on metabolism in vivo. Furthermore, metabolites were identified based on UPLC-MS/MS.

Keywords: Deuteration; fluorine-18; metabolism; murine liver microsomes; positron emission tomography; radiometabolite; radiotracer; selective COX-2 inhibitors (Coxibs); side chain elongation

Permalink: https://www.hzdr.de/publications/Publ-31056
Publ.-Id: 31056


Figure and data from 'Surface Modification of Silicon Nanowire Based Field Effect Transistors with Stimuli Responsive Polymer Brushes for Biosensing Applications'

Baraban, L.; Klinghammer, S.; Rauch, S.; Uhlmann, P.; Pregl, S.; Cuniberti, G.

Figure compilations with the access to the origin files of the graphs. Created by Stephanie Klinghammer and Larysa Baraban: fabrication of SiNQ, measurements)

Keywords: polymer brushes functionalization; iv curves

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-20
    DOI: 10.14278/rodare.339

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Permalink: https://www.hzdr.de/publications/Publ-31055
Publ.-Id: 31055


Tales from the Trenches: Developing sciview, a new 3D viewer for the ImageJ community

Günther, U.; Harrington, K. I. S.

ImageJ/Fiji is a widely-used tool in the biomedical community for performing everyday image analysis tasks. However, its 3D viewer component (aptly named 3D Viewer) has become dated and is no longer actively maintained. We set out to create an alternative tool that not only brings modern concepts and APIs from computer graphics to ImageJ, but is designed to be robust to long-term, open-source development. To achieve this we divided the visualization logic into two parts: the rendering framework, scenery, and the user-facing application, sciview. In this paper we describe the development process and design decisions made, putting an emphasis on sustainable development, community building, and software engineering best practises. We highlight the motivation for the Java Virtual Machine (JVM) as a target platform for visualisation applications. We conclude by discussing the remaining milestones and strategy for long-term sustainability.

Keywords: Software development techniques; rendering; graphics

Permalink: https://www.hzdr.de/publications/Publ-31054
Publ.-Id: 31054


Particle dataset for constructing mineral processing case studies

Pereira, L.; Frenzel, M.; Khodadadzadeh, M.; Tolosana Delgado, R.; Gutzmer, J.

This file contains a train and a test datasets that can be used to construct fictional mineral processing studies, on a particle level, using known equations for different separation techniques. This data was collected with a mineral liberation analyzer at the Helmholtz Institute Freiberg for Resource Technology. The probabilities, and classes present together with the data are part of a publication in the journal of cleaner production. These could be simply removed in order to construct new cases.

Keywords: particle-tracking; geometallurgy; mineral processing modelling; flotation; automated mineralogy; resource efficiency

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-19
    DOI: 10.14278/rodare.335
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31053
Publ.-Id: 31053


Charged pion production in Au+Au collisions at sqrt(s_NN) = 2.4 GeV

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Boehmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Ciepal, I.; Deveaux, C.; Dreyer, J.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Froehlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhaeuser, R.; Glaessel, S.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kohls, M.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Malige, A.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Muentz, C.; Muenzer, R.; Naumann, L.; Nowakowski, K.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Pysz, K.; Ramos, S.; Ramstein, B.; Reshetin, A.; Rodriguez-Ramos, P.; Rathod, N.; Rosier, P.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Singh, U.; Smyrski, J.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Stroebele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wojcik, D.; Zanevsky, Y.; Zumbruch, P.

We present high-statistic data on charged pion emission from Au+Au collisions at sqrt(s_NN) = 2.4 GeV (corresponding to E_beam = 1.23 A GeV) in four centrality classes in the range 0 - 40% of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the world data, but undershoot by 2.5σ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations.

Permalink: https://www.hzdr.de/publications/Publ-31052
Publ.-Id: 31052


Nonlinear losses in magnon transport due to four-magnon scattering

Hula, T.; Schultheiß, K.; Buzdakov, A.; Körber, L.; Bejarano, M.; Flacke, L.; Liensberger, L.; Weiler, M.; Shaw, J. M.; Nembach, H. T.; Faßbender, J.; Schultheiß, H.

We report on the impact of nonlinear four-magnon scattering on magnon transport in microstructured waveguides with low magnetic damping. Using microfocused Brillouin light scattering, we analyze magnon propagation lengths in a broad range of excitation powers and observe a decrease of the attenuation length at high powers, which is consistent with the onset of nonlinear four-magnon scattering. Hence, when measuring magnon propagation lengths and deriving damping parameters from those results, one needs to be careful to stay in the linear regime. Otherwise, the intrinsic nonlinearity of magnetization dynamics may lead to a misinterpretation of magnon propagation lengths and, thus, to wrong values of the magnetic damping of the system.

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  • Secondary publication expected from 27.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31050
Publ.-Id: 31050


Classification of the source of treatment deviation in proton therapy using prompt-gamma imaging information

Khamfongkhruea, C.; Berthold, J.; Janssens, G.; Petzoldt, J.; Smeets, J.; Pausch, G.; Richter, C.

Purpose: Prompt-gamma imaging (PGI) based range verification has been successfully implemented in clinical proton therapy recently and its sensitivity to detect treatment deviations is currently investigated. The cause of treatment deviations can be multiple - e.g. CT-based range prediction, patient setup, and anatomical changes. Hence, it would be beneficial, if PGI-based verification would not only detect a treatment deviation but would also be able to directly identify its most probable source. Here, we propose a heuristically derived decision tree approach to automatically classify the sources of range deviation in proton pencil-beam scanning (PBS) treatments of head and neck tumors based on range information obtained with a PGI slit camera.
Materials and Methods: The decision tree model was iteratively generated on a training dataset of different anatomical complexities, for an anthropomorphic head phantom and patient CT data (planning and control CTs) from 5 patients. Different range prediction errors, setup changes and relevant and non-relevant anatomical changes were introduced or derived from control CTs, summing up to a total of 98 training scenarios. Independent validation was performed for another 98 scenarios, derived solely from patient CT data of another 7 patients. PBS head and neck treatment plans were generated for the nominal scenario. For all PBS spots in the investigated field, PGI profiles were simulated using a dedicated analytical model of the slit camera for the nominal as well as the different error scenarios. From comparison of PGI profiles for nominal and error scenarios, a spot-wise range shift was determined for each error scenario. The heuristic approach includes a pre-filtering of the most suitable PBS spots for PGI treatment verification. From the validation, the accuracy, sensitivity and specificity of the model were determined.
Results: A five-step consecutive filter was developed to pre-select PBS spots. On average, 31% of spots (1044 spots) remained as input for the classification model. The derived heuristic decision tree model is based on five parameters: The coefficient of determination (R2), the slope and intercept of the linear regression between PGI-derived range shifts and the respectively predicted proton ranges for the investigated PBS spots, as well as the average and standard deviation of the PGI-derived shifts. With this approach, 94 of 98 error scenarios could be classified correctly in validation (accuracy of 96%). A sensitivity and specificity of 100% and 86% was reached.
Conclusions: In this simulation study it was demontrated that the source of a treatment deviation can be identified from simulated PGI information in head and neck tumor treatments with high sensitivity and specificity. The application, refinement and evaluation of the approach on measured PGI data will be the next step to show the clinical feasibility of PGI-based error source classification.

Permalink: https://www.hzdr.de/publications/Publ-31049
Publ.-Id: 31049


Antihypertensive use differentially associated with lower cerebral blood flow in older people with hypertension

van Dalen, J. W.; Mutsaerts, H. J.; Petr, J.; Caan, M. W.; Moll Van Charante, E. P.; Macintosh, B. J.; van Gool, W. A.; Nederveen, A. J.; Richard, E.

Consistent cerebral blood flow (CBF) is fundamental to brain function. Cerebral autoregulation ensures CBF stability. Chronic hypertension can lead to disrupted cerebral autoregulation in older people, potentially leading to blood pressure levels interfering with CBF. We investigated the associations of CBF with blood pressure and antihypertensive treatment, using arterial spin labelling MRI, in a prospective longitudinal cohort of 186 community-dwelling older individuals (77±3 years, 53% female) with hypertension, 125 (67%) of whom with 3-year follow-up. We assessed concurrent and longitudinal associations of diastolic blood pressure, systolic blood pressure, mean arterial pressure, pulse pressure, and antihypertensive drug use, with grey matter and white matter CBF (mL/100g/min), and the CBF spatial coefficient of variation (SCoV): a measure of CBF heterogeneity which may be more sensitive to cerebrovascular damage. We found no associations between blood pressure and concurrent CBF, nor between changes in blood pressure and CBF over 3-year follow-up. Antihypertensive use was associated with lower CBF and higher SCoV. Within antihypertensive types, calcium channel blockers and angiotensin receptor blockers were not associated with lower CBF. This aligns with previous evidence suggesting a protective effect of these antihypertensive classes on dementia, and may provide an important lead for future research.

Permalink: https://www.hzdr.de/publications/Publ-31048
Publ.-Id: 31048


A radiopharmacologist's and radiochemist's view on targeting the Eph/ephrin receptor tyrosine kinase system

Neuber, C.; Belter, B.; Mamat, C.; Pietzsch, J.

In the last decade, there have been extensive efforts to open up the Eph/ephrin subfamily of the receptor tyrosine kinase family for diagnostic and therapeutic applications. Besides classical pharmaceutical developments, which focus either on drugs targeting the extracellular ligand binding domains or the intracellular tyrosine kinase domains of these receptors, there also have been first radiopharmaceutical approaches. Here the focus is on the development of specific and selective probes for molecular imaging, particularly, by means of positron emission tomography, and the functional characterization of the Eph/ephrin subfamily in certain target tissues. The aim of this mini-review is to summarize the different approaches towards Eph-targeting radiotracers by using antibodies, peptides, and small molecules, and to discuss their radiopharmacological characterization. With regard to the small molecules, further considerations will focus on the design and synthesis of non-radioactive reference compounds and precursors as well as on radiolabeling strategies.

Keywords: Antibodies; cancer theranostics; extracellular ligand; fluorine-18; peptides; positron emission tomography; radiotracer; receptor tyrosine kinases; tyrosine kinase inhibitors; small molecule

Permalink: https://www.hzdr.de/publications/Publ-31047
Publ.-Id: 31047


Anisotropic exclusion effect between photocatalytic Ag/AgCl Janus particles and passive beads in a dense colloidal matrix

Huang, T.; Gobeil, S.; Wang, X.; Misko, V.; Nori, F.; de Malsche, W.; Faßbender, J.; Makarov, D.; Cuniberti, G.; Baraban, L.

Synthetic nano- and micromotors interact with each other and their surroundings in a complex manner. Here, we report on the anisotropy of active-passive particle interaction in a soft matter system containing an immobile yet photochemical Ag/AgCl-based Janus particle embedded in a dense matrix of passive beads in pure water. The asymmetry in the chemical gradient around the Janus particle, triggered upon visible light illumination, distorts the isotropy of the surrounding electric potential and results in the repulsion of adjacent passive beads to a certain distance away from the Janus particle. This exclusion effect is found to be anisotropic with larger distances to passive beads in front of the Ag/AgCl cap of the Janus particle. We provide insight into this phenomenon by performing the angular analysis of the radii of exclusion and tracking their time evolution at the level of a single bead. Our study provides a novel fundamental insight into the collective behavior of a complex mixture of active and passive particles and is relevant for various application scenarios, e.g., particle transport at micro- and nanoscale and local chemical sensing.

Keywords: photocatalytic reaction; micro and nanomotors; visible light; active Janus particles; spherical colloidal particles; exclusion phenomena

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-18
    DOI: 10.14278/rodare.329
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31046
Publ.-Id: 31046


Annual Report 2019 - Institute of Ion Beam Physics and Materials Research

Faßbender, J.; Helm, M.; Zahn, P.

The Institute of Ion Beam Physics and Materials Research conducts materials research for future applications in, e.g., information technology. To this end, we make use of the various possibilities offered by our Ion Beam Center (IBC) for synthesis, modification, and analysis of thin films and nanostructures, as well as of the free-electron laser FELBE at HZDR for THz spectroscopy. The analyzed materials range from semiconductors and oxides to metals and magnetic materials. They are investigated with the goal to optimize their electronic, magnetic, optical as well as structural functionality. This research is embedded in the Helmholtz Association’s programme “From Matter to Materials and Life”. Seven publications from last year are highlighted in this Annual Report to illustrate the wide scientific spectrum of our institute.
After the scientific evaluation in the framework of the Helmholtz Programme-Oriented Funding (POF) in 2018 we had some time to concentrate on science again before end of the year a few of us again had to prepare for the strategic evaluation which took place in January 2020, which finally was also successful for the Institute.
In 2019, there have been a number of organizational changes. First, and most prominently, we were able to hire Prof. Dr. Anton Wallner as new head of our department Accelerator Mass Spectrometry (AMS) and Isotope Research. This appointment is jointly with the TU Dresden where Toni has recei¬ved a chair in the Institute of Nuclear and Particle Physics. Along with this employment, our scientific advisory board and board of trustees approved the acquisition of a dedicated 1 MV accele¬rator for AMS including a laser detachment system. With this move, we hope to widen the scope of the user facility Ion Beam Center to new user communities in the field of nuclear astrophysics, environmental and geosciences. Second, the department Ion Beam Center is now headed by Dr. Stefan Facsko, who took over the responsibility from Dr. Johannes von Borany who stepped down for partial retirement. Stefan has been working in the Ion Beam Center since 2003 in various functions and is one of our most established researchers. We wish him all the best for this responsible position. Third, after the successful evaluation of Dr. Denys Makarov we created a new department Intelligent Materials and Devices, which is now headed by Denys. For his outstanding work in the field of mag¬netic sensor technology he also received the HZDR Research Award 2019. In the same ceremony, Dr. Jacob König-Otto received the HZDR Doctoral Prize 2019 for his dissertation at our Institute. Fourth, in fall we struck a new path and created a young researcher group on “Immuno-oncology on a chip: nano-assisted screening for cancer therapy” across disciplines and Institutes headed by Dr. Larysa Baraban. Larysa heads a group in the Institute of Radiopharmaceutical Cancer Research and collabo¬rates closely with our colleagues Dr. Artur Erbe on nanodevices and Dr. Denys Makarov on sensorics. We believe that this synergetic approach will pave the way to a fast and cost-efficient screening technology for personalized health care.
Again, in 2019, the level of newly received third-party funding was very good. In particular, we received the funding for two Helmholtz Innovation Laboratories (HIL); one on thermal treatment technology for defect engineering (UltraTherm) headed by Dr. Lars Rebohle and one on flexible sensors (FlexiSens) headed by Dr. Denys Makarov. The main emphasis of both HILs is to provide support of and technology transfer to small and medium enterprises in the respective technological areas. We are sure that in addition to our ion technology service provided via the HZDR Innovation GmbH both Innovation Labs will boost our technology transfer activities.
Several conferences and workshops were organized by scientists from our institute: the “Ion Beam Physics Workshop” as the annual meeting of the German Ion Beam Community was organized by Dr. Stefan Facsko and attracted around 50 participants to discuss the newest national developments and research in the field of ion beam physics. In addition, the “3rd European Focused Ion Beam Network Workshop” was organized by Dr. Hans-Jürgen Engelmann and co-workers; 135 participants from 17 countries found their way to HZDR to discuss current research topics and exchange experience in Focused-Ion-Beam (FIB) and Scanning-Electron-Microscopy (SEM) work.
Finally, we would like to cordially thank all partners, friends, and organizations who supported our progress in 2019. Special thanks are due to the Executive Board of the Helmholtz-Zentrum Dresden-Rossendorf, the Minister of Science and Arts of the Free State of Saxony, and the Ministers of Education and Research, and of Economic Affairs and Energy of the Federal Government of Germany. Numerous partners from universities, industry and research institutes all around the world contributed essentially, and play a crucial role for the further development of the institute. Last but not least, the directors would like to thank again all members of our institute for their efforts and excellent contributions in 2019.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-109 2020
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-31045
Publ.-Id: 31045


Soft Hydrothermal Synthesis of Hafnon, HfSiO4

Estevenon, P.; Kaczmarek, T.; Rafiuddin, M. R.; Welcomme, E.; Szenknect, S.; Mesbah, A.; Moisy, P.; Poinssot, C.; Dacheux, N.

The conditions allowing the preparation of single phase HfSiO4 has been determined through a multiparametric study by varying the concentrations of the reactants, the pH of the reactive media or the temperature and duration of the hydrothermal treatment. HfSiO4 was prepared through relatively soft conditions (pH ≤ 1.6, CSi ≈ CHf 0.21 mol·L‑1, T ≥ 150°C for t ≥ 24 hours).

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-01-29
    DOI: 10.14278/rodare.327

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Permalink: https://www.hzdr.de/publications/Publ-31043
Publ.-Id: 31043


Yu-Shiba-Rusinov bands in ferromagnetic superconducting diamond

Zhang, G.; Samuely, T.; Iwahara, N.; Kačmarčík, J.; Wang, C.; May, P. W.; Jochum, J. K.; Onufriienko, O.; Szabó, P.; Zhou, S.; Samuely, P.; Moshchalkov, V. V.; Chibotaru, L. F.; Rubahn, H.-G.

The combination of different exotic properties in materials paves the way for the emergence of their new potential applications. An example is the recently found coexistence of the mutually antagonistic ferromagnetism and superconductivity in hydrogenated boron-doped diamond, which promises to be an attractive system with which to explore unconventional physics. Here, we show the emergence of Yu-Shiba-Rusinov (YSR) bands with a spatial extent of tens of nanometers in ferromagnetic superconducting diamond using scanning tunneling spectroscopy. We demonstrate theoretically how a two-dimensional (2D) spin lattice at the surface of a three-dimensional (3D) superconductor gives rise to the YSR bands and how their density-of-states profile correlates with the spin lattice structure. The established strategy to realize new forms of the coexistence of ferromagnetism and superconductivity opens a way to engineer the unusual electronic states and also to design better-performing superconducting devices.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31042
Publ.-Id: 31042


In situ study of the synthesis of thorite (ThSiO4) under environmental representative conditions

Estevenon, P.; Causse, J.; Szenknect, S.; Welcomme, E.; Mesbah, A.; Moisy, P.; Poinssot, C.; Dacheux, N.

Thorite, ThSiO4 with Zircon structure type, is one of the most abundant natural source of thorium on earth. While actinides are known to form nanoparticles in silicate medium, no direct link between those colloids and crystalline form of thorite was evidenced until now. Here we show that thorite can be produced in experimental conditions close to environmental pH and temperature. Thanks to in-situ Small and Wide Angle X-rays Scattering (SWAXS) measurements, colloids of a few nanometers are first evidenced for low reaction time. These colloids exhibit elongated shapes and finally tend to aggregate after the size has reached 10 nm. Once aggregated, the system goes through a maturation step finishing with the emergence of nanocrystallites presenting thorite zircon structure. This maturation step is longer when the reaction temperature is decreased highlighting kinetic considerations. The conclusions of this article have potential implications in the paragenesis of Th minerals deposits, but also in the behaviour of Th and, by analogy, tetravalent actinides in the environment. The Th-silicate colloids evidenced in this work have, at low temperature and at near neutral pH, a long-term stability and a morphology in favor of a high mobility in groundwaters. If these species are formed in more diluted media, this could be problematic regarding to the spreading of Th and, by analogy of others tetravalent actinides in the environment.

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  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-12
    DOI: 10.14278/rodare.325

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Permalink: https://www.hzdr.de/publications/Publ-31041
Publ.-Id: 31041


Formation of PuSiO4 under hydrothermal conditions

Estevenon, P.; Welcomme, E.; Tamain, C.; Jouan, G.; Szenknect, S.; Mesbah, A.; Poinssot, C.; Moisy, P.; Dacheux, N.

Attempts to synthesize plutonium (IV) silicate, PuSiO4, have been performed on the basis of the results recently reported in the literature for CeSiO4, ThSiO4 and USiO4 under hydrothermal conditions. Although it was not possible to prepare PuSiO4 by applying the conditions reported for thorium and uranium, an efficient way of PuSiO4 synthesis was established following those optimized for CeSiO4 system. This method was based on the slow oxidation of plutonium (III) silicate reactants under hydrothermal conditions at 150°C in hydrochloric acid (pH = 3 – 4). This result shed a new light on the potential behavior of plutonium in reductive environment, highlighted the representativeness of cerium surrogates to study plutonium in such conditions and brought some important pieces of information on plutonium chemistry in silicate solutions.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-04-20
    DOI: 10.14278/rodare.295

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Permalink: https://www.hzdr.de/publications/Publ-31040
Publ.-Id: 31040


The Serial Interface Package -- v3.0

Seilmayer, M.

The package enables reading and writing binary and ASCII data to RS232/RS422/RS485 or any other virtual serial interface of the computer. The major extensions are made with new functions and an improved robustness.

Keywords: RS232; RS485; serial interface; R

  • Software in external data repository
    Publication year 2020
    Programming language: R, Tcl/TK
    System requirements: Windows, Linux, MacOS
    License: GPL-2Link to location

Permalink: https://www.hzdr.de/publications/Publ-31039
Publ.-Id: 31039


MR-guided proton therapy: a review and a preview

Hoffmann, A.; Oborn, B.; Moteabbed, M.; Yan, S.; Bortfeld, T.; Knopf, A.; Fuchs, H.; Georg, D.; Seco, J.; Francesca Spadea, M.; Jäkel, O.; Kurz, C.; Parodi, K.

Background
The targeting accuracy of proton therapy (PT) for moving soft-tissue tumours is expected to greatly improve by real-time magnetic resonance imaging (MRI) guidance. The integration of MRI and PT at the treatment isocenter would offer the opportunity of combining the unparalleled soft-tissue contrast and real-time imaging capabilities of MRI with the most conformal dose distribution and best dose steering capability provided by modern PT. However, hybrid systems for MR-integrated PT (MRiPT) have not been realized so far due to a number of hitherto open technological challenges. In recent years, various research groups have started addressing these challenges and exploring the technical feasibility and clinical potential of MRiPT. The aim of this contribution is to review the different aspects of MRiPT, to report on the status quo and to identify important future research topics.

Methods
Four aspects currently under study and their future directions are discussed: modelling and experimental investigations of electromagnetic interactions between the MRI and PT systems, integration of MRiPT workflows in clinical facilities, proton dose calculation algorithms in magnetic fields, and MRI-only based proton treatment planning approaches.

Conclusions
Although MRiPT is still in its infancy, significant progress on all four aspects has been made, showing promising results that justify further efforts for research and development to be undertaken. First non-clinical research solutions have recently been realized and are being thoroughly characterized. The prospect that first prototype MRiPT systems for clinical use will likely exist within the next 5 to 10 years seems realistic, but requires significant work to be performed by collaborative efforts of research groups and industrial partners.

Keywords: Proton therapy; magnetic resonance imaging; image guidance

Permalink: https://www.hzdr.de/publications/Publ-31038
Publ.-Id: 31038


Clinical outcome of PSMA-guided radiotherapy for patients with oligorecurrent prostate cancer

Koerber, S. A.; Sprute, K.; Kratochwil, C.; Winter, E.; Haefner, M. F.; Katayama, S.; Schlampp, I.; Herfarth, K.; Kopka, K.; Afshar-Oromieh, A.; Zschaebitz, S.; Holland-Letz, T.; Choyke, P. L.; Jaeger, D.; Hohenfellner, M.; Haberkorn, U.; Debus, J.; Giesel, F. L.

Purpose.
First-line treatment of patients with recurrent, metastatic prostate cancer involves hormone therapy with or without additional systemic therapies. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) allows the detection of oligometastatic disease that may be amenable to image-guided radiotherapy. The current study classifies the type and localization of metastases and the clinical outcome of PSMA-PET/CT-guided radiotherapy to selected metastases.
Materials and methods.
Between 2011 and 2019, 86 patients with recurrent, oligometastatic prostate carcinoma were identified by PSMA-PET/CT and were treated with image-guided radiotherapy of their metastases. Sites of relapse were characterized, and the primary endpoint overall survival (OS), biochemical progression-free survival (bPFS), and androgen deprivation therapy (ADT)-free survival were tabulated.
Results
In total, 37% of the metastases were bone metastases, 48% were pelvic nodalmetastases, and 15% were nodalmetastases outside of the pelvis. After PSMA-guided radiotherapy, a biochemical response was detected in 83% of the cohort. A statistically significant decrease in the standard uptake value (SUV) was seen in irradiated metastases. After a median follow-up of 26 months, the 3-year OS and bPFS were 84% and 55%, respectively. The median time of ADT-free survival was 13.5 months. A better clinical outcome was observed for patients receiving concomitant ADT or more than 24 fractions of radiation.
Conclusion.
PSMA-guided radiotherapy is a promising therapeutic approach with excellent infield control for men with oligorecurrent prostate carcinoma. However, prospective, randomized trials are necessary to determine if this approach confers a survival advantage.

Keywords: Prostate cancer; PSMA; PET; Metastases; SUV; OS

Permalink: https://www.hzdr.de/publications/Publ-31037
Publ.-Id: 31037


Oscillatory surface deformation of paramagnetic rare earth solutions driven by an inhomogeneous magnetic field

Fritzsche, B.; Mutschke, G.; Meinel, T.; Yang, X.; Lei, Z.; Eckert, K.

The deformation of the free surface of a paramagnetic liquid subjected to a non-uniform magnetic field has been studied. A transient deformation of the surface caused by the interplay of gravity, magnetic field and surface tension is observed when a permanent magnet is moved vertically downwards to the free surface of the liquid. Different concentrations of rare-earth metal salt (DyCl 3 ) were used and different magnet velocities were studied. The deformation of the interface was followed optically by means of a microscope and recorded with a high-speed camera. The experimental results are compared and discussed with complementary numerical simulations. Detailed results are given for the static shape of the deformed surface and the temporal evolution of the surface deformation below the center of the magnet. The frequency of the surface oscillations is found to depend on the concentration of the salt and is compared with analytical findings. Finally, a potential application of the effects observed is presented.

Keywords: Magnetic field; magnetic gradient force; rare earth; dysprosium; interfacial instability; free surface; oscillations

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Permalink: https://www.hzdr.de/publications/Publ-31036
Publ.-Id: 31036


Characterization of magnetic interference and image artefacts during simultaneous in-beam MR imaging and proton pencil beam scanning

Gantz, S.; Hietschold, V.; Hoffmann, A. L.

For the first time, a low-field open magnetic resonance (MR) scanner was combined with a proton pencil beam scanning (PBS) research beamline. The aim of this study was to characterize the magnetic fringe fields produced by the PBS system and measure their effects on MR image quality during simultaneous PBS irradiation and image acquisition. A magnetic field camera measured the change in central resonance frequency (Δfres) and magnetic field homogeneity (ΔMFH) of the B0 field of the MR scanner during operation of the beam transport and scanning magnets. The beam energy was varied between 70−220 MeV and beam scanning was performed along the central horizontal and vertical axis of a 48 × 24 cm2 radiation field. The time structure of the scanning magnets’ fringe fields was simultaneously recorded by a tri-axial Hall probe. MR imaging experiments were conducted using the ACR (American College of Radiology) Small MRI Phantom and a spoiled gradient echo pulse sequence during simultaneous volumetric irradiation. Computer simulations were performed to predict the effects of B0 field perturbations due to PBS irradiation on MR image formation in k-space. Setting the beam transport magnets, horizontal and vertical scanning magnets resulted in a maximum Δfres of 50, 235 and 4 Hz, respectively. The ΔMFH was less than 3 ppm for all measurements. MR images acquired during beam energy variation and vertical beam scanning showed no visual loss in image quality. However, MR images acquired during horizontal beam scanning showed severe coherent ghosting artefacts in phase encoding direction. Both simulated and measured k-space phase maps prove that these artefacts are caused by phase-offsets. This study shows first experimental evidence that simultaneous in-beam MR imaging during proton PBS irradiation is subject to severe loss of image quality in the absence of magnetic decoupling between the PBS and MR system.

Keywords: MRI; proton therapy; image quality; pencil beam scanning; magnetometry

Permalink: https://www.hzdr.de/publications/Publ-31035
Publ.-Id: 31035


Broadband Infrared LEDs based on Europium-To-Terbium Charge Transfer Luminescence

Joos, J.; van der Heggen, D.; Martin, L.; Amidani, L.; Smet, P.; Barandiarán, Z.; Seijo, L.

A broadband infrared (IR) light-emitting diode (LED) for versatile spectroscopic use is constructed, based on a novel type of broadband IR luminescence. This peculiar emission is identified in europium and terbium codoped CaS for which the spectrum partially overlaps with the red Eu2+ emission and ranges up to 1200 nm. It can be efficiently excited with visible light. Experimental evidence for metal-to-metal charge transfer (MMCT) luminescence is collected, comprising data from luminescence spectroscopy, microscopy and X-ray spectroscopy. State-of-the-art multiconfigurational ab initio calculations allow to attribute the infrared band to the radiative decay of a metastable MMCT state of a Eu2+-Tb3+ pair. The calculations explain why no MMCT emission is found in the similar compound SrS:Eu,Tb and are used to anticipate how to fine-tune the characteristics of the MMCT luminescence.

Permalink: https://www.hzdr.de/publications/Publ-31034
Publ.-Id: 31034


Determination of thermodynamic functions and structural parameters of NpO2+ lactate complexes

Maiwald, M. M.; Müller, K.; Heim, K.; Trumm, M.; Fröhlich, D. R.; Banik, N. L.; Rothe, J.; Dardenne, K.; Skerencak-Frech, A.; Panak, P. J.

The complexation of NpO2+ with lactate in aqueous solution is studied as a function of the total ligand concentration ([Lac-]total), ionic strength (Im = 0.5 – 4.0 mol kg-1 Na+(Cl-/ClO4-)) and temperature (T = 20 – 85 °C) by Vis/NIR absorption spectroscopy. The formation of two NpO2+ lactate species with the stoichiometry NpO2(Lac)n1-n (n = 1, 2) is observed at the studied experimental conditions. The temperature dependent conditional stability constants log beta 'j(T) at different ionic strengths are calculated with the law of mass action. The conditional data are extrapolated to IUPAC reference state conditions (Im = 0) with the specific ion interaction theory (SIT). With increasing temperature up to 85 °C log beta 01(20 °C) = 1.92 ± 0.14 decreases by 0.12 and log beta 02(20 °C) = 2.10 ± 0.13 decreases by 0.17. The thermodynamic stability constants correlate linearly with the reciprocal temperature according to the integrated Van’t Hoff equation. Thus, linear regression analyses yield the standard reaction enthalpy delta rH0 and entropy delta rS0 for the complexation reactions. In addition, the sum of the SIT specific binary ion-ion interaction coefficients delta epsilon j,k(T) of the complexation reactions are determined by variation of the ionic strength.
Structural parameters of the formed complex species and the coordination mode of lactate towards the NpO2+ ion are investigated as a function of pHc by extended x-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FT IR). The results show, that the coordination mode of lactate changes from end-on (coordination via only the COO- group) to side-on (formation of chelate rings involving the OH-group) with increasing pHc. The experiments are supported by quantum chemical calculations.

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  • Secondary publication expected from 22.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31033
Publ.-Id: 31033


The role of postoperative thoracic radiotherapy and prophylactic cranial irradiation in early stage small cell lung cancer: patient selection among ESTRO experts

Putora, P.; de Ruysscher, D.; Glatzer, M.; Widder, J.; van Houtte, P.; Troost, E. G. C.; Slotman, B.; Ramella, S.; Pöttgen, C.; Peeters, S.; Nestle, U.; Mcdonald, F.; Le, P. C.; Dziadziuszko, R.; Belderbos, J.; Faivre-Finn, C.

The role of prophylactic cranial irradiation (PCI) and thoracic radiotherapy (TRT) is unclear in resected small cell lung cancer (SCLC). Methods: Thirteen European radiotherapy experts on SCLC were asked to describe their strategies on PCI and TRT for patients with resected SCLC. The treatment strategies were converted into decision trees and analyzed for consensus and discrepancies. Results: For patients with resected SCLC and positive lymph nodes most experts recommend prophylactic cranial irradiation and thoracic radiotherapy. For elderly patients with resected node negative SCLC, most experts do not recommend thoracic radiotherapy or prophylactic cranial irradiation. Conclusion: PCI and TRT are considered in patients with resected SCLC and these treatments should be discussed with the patient in the context of shared decision-making.

Permalink: https://www.hzdr.de/publications/Publ-31032
Publ.-Id: 31032


Is reducing irradiated margins key to improving outcomes for radiotherapy

van Herk, M.; Osorio, E.; Troost, E. G. C.

Radiotherapy is a four-dimensional geometrical challenge. For modern radiotherapy planning, gross tumour volume (GTV) is pictured before treatment using CT scanning fused with anatomical and functional imaging. To account for microscopic tumour spread, a safety margin is added to the GTV and corrected for anatomical boundaries to determine the clinical target volume (CTV). Finally, systematic and random errors occurring during the fractionated course of radiotherapy are corrected for by adding another safety margin.

  • Lancet Oncology 20(2019)9, 1208-1210

Permalink: https://www.hzdr.de/publications/Publ-31031
Publ.-Id: 31031


Integral multi-scenario robustness evaluation of classical and anatomical robust optimization in head and neck cancer proton therapy

Cubillos Mesias, M.; Troost, E. G. C.; Lohaus, F.; Agolli, L.; Rehm, M.; Richter, C.; Stützer, K.

Classical robust optimization considers uncertainties in patient setup and particle range. Usually plan robustness is evaluated from calculation of perturbed dose distributions based on the planning CT, without considering potential anatomical changes that may occur during the treatment course. Our aim was to compare the overall plan robustness of classical robust optimization (cRO) with the recently proposed anatomical robust optimization (aRO) based on an integral multi-scenario evaluation, considering all types of uncertainties including anatomical variations.

  • Abstract in refereed journal
    Radiotherapy and Oncology 133(2019)1, S488-S489

Permalink: https://www.hzdr.de/publications/Publ-31030
Publ.-Id: 31030


Combined Two-phase Co-flow and Counter-flow in a Gas Channel/Porous Transport Layer Assembly

Beale, S. B.; Andersson, M.; Weber, N.; Marschall, H.; Lehnert, W.

Polymer electrolyte fuel cells and electrolysers are low temperature devices whereby both gases and liquids intermingle within the porous transport layers and open channels. The flow of the liquid and gas is of paramount importance to the functioning of the unit. This motion is poorly understood. Cell-level models typically employ volume-averaging techniques to describe the motion of the flowing reactants and products. Until recently, detailed analysis of the two-phase liquid gas mixture, employing front-tracking methods has proved to be computationally prohibitive. Previous work has considered the motion of liquid drops in gas channels, it being assumed the drops are formed at specific nucleation sites on the sides of the channels. The present work considers a detailed numerical analysis of combined liquid-gas co-flow in a gas channel with liquid-gas counter-flow in a porous transport layer, (PTL). The geometry considered is in the form of a ‘T-shape’ with the porous transport layer of a thin rectangular prism of dimensions 0.5×0.5×0.1 mm3 located at the base of the ‘T’, and the gas flowing across the top in channel. The PTL is reproduced by digital reconstruction of nano-computer tomography images of a Freudenberg H2315 PTL as a sterolithography file. From this, the domain is tessellated with an unstructured castellated, or octree, type mesh. Liquid water is introduced at an electrode at the base of the PTL and gaseous oxygen is simultaneously removed by electrochemical reduction; the resulting liquid-gas counter flow in the porous transport layer results in liquid droplets being entrained in co-flow in the gas channels and convected downstream.

The equations of mass and momentum are solved by means of the open source software library OpenFOAM. A volume-of-fluid approach based on the multidimensional universal limiter for explicit solution was employed within a volume-of-fluid method. At T = 0, the channel is presumed to be filled with gas, and the PTL saturated with liquid water. Gas is introduced at the inlet at a given velocity. Water is added and gas removed at the electrode (counter flow) whereas both water and gas are removed at the outlet (coflow). At the channel and PTL walls as well as on the GDL fibres, the static contact angle was fixed. It can be seen that the location and size of the shed drops varies somewhat in space and time, i.e., there is a stochastic component to the motion of the fluid, due to the spatial distribution of the fibres in the PTL, the transient shedding process, and the merging of liquid streams flowing into the gas channel. Nonetheless, a definite periodicity is observed with drops being injected into the channel at a fairly regular rate. Some relatively minor switching with time is observed within the PTL due to the random packing of fibres, but again these transients are relatively quiescent, as might be expected for porous media flow.

In addition to providing new and important information about flow and pressure losses in channels and PTLs of electrochemical cells as a function of gas and liquid flow rates, i.e. current density and stoichiometry, the present model may be also used to enumerate properties such as relative permeability which can subsequently be employed in cell-scale models.

  • Lecture (Conference)
    PRiME 2020, 04.-09.10.2020, Honolulu, USA
  • Open Access Logo ECS Transactions 98(2020)9, 305-315
    DOI: 10.1149/09809.0305ecst

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Permalink: https://www.hzdr.de/publications/Publ-31029
Publ.-Id: 31029


Nanopatterning of the (001) surface of crystalline Ge by ion irradiation at off-normal incidence: Experiment and simulation

Erb, D.; de Schultz, R.; Ilinov, A.; Nordlund, K.; Bradley, M. R.; Facsko, S.

Intricate topographical patterns can form on the surface of crystalline Ge(001) subject to low-energy ion irradiation in the reverse epitaxy regime, i.e., at elevated temperatures which enable dynamic recrystallization. We compare such nanoscale patterns produced by irradiation from varied polar and azimuthal ion incidence angles with corresponding calculated surface topographies. To this end, we propose a continuum equation including both anisotropic erosive and anisotropic diffusive effects. Molecular dynamics simulations provide the coefficients of angle-dependent sputter erosion for the calculations. By merely changing these coefficients accordingly, the experimentally observed surface morphologies can be reproduced, except for extreme ion incidence angles. Angle-dependent sputter erosion is thereby identified as a dominant mechanism in ion-induced pattern formation on crystalline surfaces under irradiation from off-normal incidence angles.

Keywords: Ion impact & scattering; Surface diffusion; Surface instabilities; Nanostructures; Vacuum interfaces; Molecular dynamics; Atomic force microscopy

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Permalink: https://www.hzdr.de/publications/Publ-31027
Publ.-Id: 31027


Visualizing Magnetic Structure in 3D Nanoscale Ni–Fe Gyroid Networks

Llandro, J.; Love, D. M.; Kovács, A.; Caron, J.; Vyas, K. N.; Kakay, A.; Salikhov, R.; Lenz, K.; Faßbender, J.; Scherer, M. R. J.; Cimorra, C.; Steiner, U.; Barnes, C. H. W.; Dunin-Borkowski, R. E.; Fukami, S.; Ohno, H.

Arrays of interacting 2D nanomagnets display unprecedented electromagnetic properties via collective effects, demonstrated in artificial spin ices and magnonic crystals. Progress toward 3D magnetic metamaterials is hampered by two challenges: fabricating 3D structures near intrinsic magnetic length scales (sub-100 nm) and visualizing their magnetic configurations. Here, we fabricate and measure nanoscale magnetic gyroids, periodic chiral networks comprising nanowire-like struts forming three-connected vertices. Via block copolymer templating, we produce Ni75Fe25 single-gyroid and double-gyroid (an inversion pair of single-gyroids) nanostructures with a 42 nm unit cell and 11 nm diameter struts, comparable to the exchange length in Ni–Fe. We visualize their magnetization distributions via off-axis electron holography with nanometer spatial resolution and interpret the patterns using finite-element micromagnetic simulations. Our results suggest an intricate, frustrated remanent state which is ferromagnetic but without a unique equilibrium configuration, opening new possibilities for collective phenomena in magnetism, including 3D magnonic crystals and unconventional computing.

Keywords: magnetic metamaterials gyroids transmission electron microscopy off-axis electron holography

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  • Secondary publication expected from 06.04.2021

Permalink: https://www.hzdr.de/publications/Publ-31026
Publ.-Id: 31026


Electron Concentration Limit in Ge Doped by Ion Implantation and Flash Lamp Annealing

Prucnal, S.; Żuk, J.; Hübner, R.; Duan, J.; Wang, M.; Pyszniak, K.; Drozdziel, A.; Turek, M.; Zhou, S.

Controlled doping with an effective carrier concentration higher than 10^20 cm-3 is a key challenge for the full integration of Ge into silicon-based technology. Such a highly doped layer of both p- and n type is needed to provide ohmic contacts with low specific resistance. We have studied the effect of ion implantation parameters i.e., ion energy, fluence, ion type, and protective layer on the effective concentration of electrons. We have shown that the maximum electron concentration increases as the thickness of the doping layer decreases. The degradation of the implanted Ge surface can be minimized by performing ion implantation at temperatures that are below -100 C with ion flux less than 60 nAcm-2 and maximum ion energy less than 120 keV. The implanted layers are flash-lamp annealed for 20 ms in order to inhibit the diffusion of the implanted ions during the recrystallization process.

Keywords: Ge; ion implantation; flash lamp annealing; n-type doping; Raman spectroscopy

Permalink: https://www.hzdr.de/publications/Publ-31025
Publ.-Id: 31025


Hydrogel-based Janus Micromotors Capped with Functional Nanoparticles for Environmental Applications

Lin, X.; Zhu, H.; Zhao, Z.; You, C.; Kong, Y.; Zhao, Y.; Liu, J.; Chen, H.; Shi, X.; Makarov, D.; Mei, Y.

Janus nano/micromotors have been developed into various sizes, shapes and functions for a blaze of applications especially in biomedical and environmental fields. Here, we report a fabrication method of Janus micromotors by capping hydrogel microspheres with functional nanoparticles (NPs). Microspheres are prepared in droplet microfluidics relying on hydrogel polymerization to obtain spheres with diameters from 20 μm to 500 μm. By solidifying a hydrogel layer onto microspheres, functional NPs of MnO2 (catalyst of H2O2), TiO2 (photocatalyst) and Fe3O4 (magnetic guidance) are adhered onto microspheres resulting in Janus micromotors revealing different functionalities. We explore dynamics of Janus micromotors (diameter around 250 µm) by analyzing their trajectories in terms of mean squared displacement (MSD) when immersed in H2O2 solutions of different concentrations, illuminated by light and guided in an external magnetic field. TiO2 Janus micromotors perform well for water purification tasks as we exemplarily demonstrate with a degradation of Methylene Blue dye in water. The proposed fabrication method is versatile and enables to achieve adjustable coverage of a microsphere with NPs as well as to realize multi-functional Janus micromotors by adhering different NPs (e.g., MnO2 and Fe3O4) on a sphere. This method provides an attractive way to fabricate multifunctional Janus micromotors in a cost-effective manner for environmental applications.

Keywords: Janus micromotors; photocurable hydrogel; functional nanoparticles; catalytic motion; environmental applications

Permalink: https://www.hzdr.de/publications/Publ-31023
Publ.-Id: 31023


High-field magnetoacoustics of a Dy2Fe14Si3 single crystal

Andreev, A. V.; Gorbunov, D.; Nomura, T.; Zvyagin, A. A.; Zvyagina, G. A.; Zherlitsyn, S.

Dy2Fe14Si3 (hexagonal crystal structure of the Th2Ni17 type) is a highly-anisotropic ferrimagnet with spontaneous magnetic moment Ms=8µB per formula unit (at 2 K), directed along the Fe sublattice, and Curie temperature TC=500 K. The magnetic anisotropy is of the easy-plane type with the [100] axis as an easy magnetization direction. Large anisotropy is observed also within the basal plane. In fields applied along the [100] and [120] axes, field-induced phase transitions were observed at 33 T (of thefirst order) and at 41 T (of the second order), respectively (at 2 K). Relative changes of sound velocity and changes of sound attenuation at these phase transitions in a Dy2Fe14Si3 single crystal were measured in pulsed magneticfields up to 58 T at 2 K and elevated temperatures. The performed theoretical analysis suggests that the interaction of the elastic subsystem with the magnetic one is of the exchange-striction nature.

Permalink: https://www.hzdr.de/publications/Publ-31022
Publ.-Id: 31022


Once daily versus radiotherapy in the management of limited disease small cell lung cancer - Decision criteria in routine practice

Glatzer, M.; Faivre-Finn, C.; de Ruysscher, D.; Widder, J.; van Houtte, P.; Troost, E. G. C.; Dahele, M.; Slotman, B.; Ramella, S.; Pöttgen, C.; Peeters, S.; Nestle, U.; Mcdonald, F.; Le Pechoux, C.; Dziadziuszko, R.; Belderbos, J.; Putora, P.

Background: In limited disease small cell lung cancer, the convert trial has demonstrated similar results with once-daily (QD) radiotherapy (66 Gy) and twice-daily (BID) radiotherapy (45 Gy). The selection among these regimes may be influenced by several factors. Methods: Thirteen European radiotherapy experts in SCLC as defined by the European Society for Therapeutic Radiation Oncology (ESTRO) were asked to describe their strategies in the management of LD-SCLC. The decision criteria were unified, the strategies were converted into decision trees and analysed for consensus and discrepancies. Results: Logistical reasons, performance status of the patient and dose constraints were the three major decision criteria used by most experts in decision making. The use of QD and BID regimes was balanced among European experts, but there was a trend towards the BID regime for fit patients able to travel twice a day to the radiotherapy site. Conclusion: BID and QD radiotherapy are both accepted treatment options among experts and the decision may be influenced by pragmatic factors such as availability of transportation.

Permalink: https://www.hzdr.de/publications/Publ-31021
Publ.-Id: 31021


Individual patient data meta-analysis of FMISO and FAZA hypoxia PET scans from head and neck cancer patients undergoing definitive radio-chemotherapy

Zschaeck, S.; Löck, S.; Hofheinz, F.; Zips, D.; Mortensen, L.; Zöphel, K.; Troost, E. G. C.; Boeke, D.; Saksoe, M.; Mönnich, D.; Seidlitz, A.; Johansen, J.; Skripcak, T.; Gregoire, V.; Overgaard, J.; Baumann, M.; Krause, M.

Background and purpose: Tumor hypoxia plays an important role in head and neck squamous cell carcinomas (HNSCC). Various positron emission tomography (PET) tracers promise non-invasive assessment of tumor hypoxia. So far, the applicability of hypoxia PET is hampered by monocentric imaging trials with few patients.
Materials and methods: Multicenter individual patient data based meta-analysis of the original PET data from four prospective imaging trials was performed. All patients had localized disease and were treated with curatively intended radio(-chemo)therapy. Hypoxia PET imaging was performed with 18F-Fluoromisonidazole (FMISO, 102 patients) or 18F-Fluoroazomycin-arabinoside (FAZA, 51 patients). Impact of hypoxia PET parameters on loco-regional control (LRC) and overall survival (OS) was analyzed by uni- and multivariable Cox regression.
Results: Baseline characteristics between participating centers differed significantly, especially regarding T stage (p<0.001), tumor volume (p<0.001) and p16 status (p=0.009). The commonly used hypoxia parameters, maximal tumor-to-muscle ratio (TMRmax) and hypoxic volume with 1.6 threshold (HV1.6), showed a strong association with LRC (p=0.001) and OS (p<0.001).
These findings were irrespective of the radiotracer and the same cut-off values could be applied for FMISO and FAZA (TMRmax>2.0 or HV1.6>1.5 ml). The effect size of TMRmax was similar for subgroups of patients defined by radiotracer, p16 status and FDG-PET parameters for LRC and OS, respectively.
Conclusion: PET measured hypoxia is robust and has a strong impact on LRC and OS in HNSCC. The most commonly investigated tracers FMISO and FAZA can probably be used equivalently in multicenter trials. Optimal strategies to improve the dismal outcome of hypoxic tumors remain elusive.

Keywords: head and neck cancer; FMISO; FAZA; PET; hypoxia

Permalink: https://www.hzdr.de/publications/Publ-31020
Publ.-Id: 31020


Bentonite Geomicrobiology

Lopez Fernandez, M.; Matschiavelli, N.; Merroun, M. L.

Bentonites may be used as a buffer and backfill material in future deep geological repositories of high-level radioactive waste. These clay formations have been reported to host different metabolically active microorganisms with the potential to affect the biogeochemical cycles of carbon, phosphorus and sulfur. Therefore, low porosity bentonites with high swelling capacity might prevent several microbial processes, such as corrosion. In addition, microorganisms occurring in bentonite may be able to interact with released radionuclides affecting their fate and behavior and leading to their mobilization or immobilization.
This chapter reviews the latest findings on the structure and composition of microbial communities in bentonites under repository relevant conditions (high temperature, high pressure, presence of electron donors/acceptors, etc.), to underline the importance of the microbial activity for the long-term effectiveness of the repository. Both, laboratory and large-scale experiment results will be summarized and discussed. In addition, the impact of microbial processes on the mobilization of radionuclides at the bentonite/microbe/radionuclide interface will be reviewed. A multidisciplinary approach combining microscopy, spectroscopy, radiochemistry and microbiology-based techniques used to study the speciation of radionuclides will be highlighted.

Keywords: bentonite; microbial diversity; microbial activity; microbial radionuclide migration; high-level radioactive waste; deep geological repository

  • Book chapter
    Jonathan R. Lloyd, Andrea Cherkouk: The Microbiology of Nuclear Waste Disposal, Netherlands: Elsevier, 2020, 978-0-12-818695-4, 137-155

Permalink: https://www.hzdr.de/publications/Publ-31019
Publ.-Id: 31019


Multi Optical Sensor Fusion for Mineral Mapping of Core Samples

Rasti, B.; Ghamisi, P.; Seidel, P.; Lorenz, S.; Gloaguen, R.

Geological objects are characterized by a high complexity inherent to a strong compositional variability at all scales and usually unclear class boundaries. Therefore, dedicated processing schemes are required for the analysis of such data for mineral mapping. On the other hand, the variety of optical sensing technology reveals different data attributes and therefore multi-sensor approaches are adapted to solve such complicated mapping problems. In this paper, we devise an adapted multi-optical sensor fusion (MOSFus) workflow which takes the geological characteristics into account. The proposed processing chain exhaustively covers all relevant stages, including data acquisition, preprocessing, feature fusion, and mineral mapping. The concept includes i) a spatial feature extraction based on morphological profiles on RGB data with high spatial resolution, ii) a specific noise reduction applied on the hyperspectral data that assumes mixed sparse and Gaussian contamination and iii) a subsequent dimensionality reduction using a sparse and smooth low rank analysis. The feature extraction approach allows to fuse heterogeneous data at variable resolutions, scales, and spectral ranges as well as improve classification substantially. The last step of the approach, an SVM classifier, is robust to unbalanced and sparse training sets and is particularly efficient with complex imaging data. We evaluate the performance of the procedure with two different multi-optical sensor datasets. The results demonstrate the superiority of this dedicated approach over common strategies.

Keywords: Multi-sensor data; optical sensor; hyperspectral; hyperspectral mixed sparse and Gaussian noise reduction (HyMiNoR); spectral imaging; data fusion; feature extraction; dimensionality reduction; support vector machine (SVM); sparse and smooth low-rank analysis (SSLRA); orthogonal total variation component analysis (OTVCA); mineral exploration

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Permalink: https://www.hzdr.de/publications/Publ-31017
Publ.-Id: 31017


Quantum and classical phase-space dynamics of a free-electron laser

Carmesin, C. M.; Peter, K.; Enno, G.; Sauerbrey, R.; Schleich, W. P.

In a quantum mechanical description of the free-electron laser (FEL), the electrons jump on discrete momentum ladders, while they follow continuous trajectories according to the classical description. In order to observe the transition from quantum to classical dynamics, it is not sufficient that many momentum levels are involved. Only if additionally the initial momentum spread of the electron beam is larger than the quantum mechanical recoil, caused by the emission and absorption of photons, the quantum dynamics in phase space resembles the classical one. Beyond these criteria, quantum signatures of averaged quantities like the FEL gain might be washed out.

Permalink: https://www.hzdr.de/publications/Publ-31016
Publ.-Id: 31016


Crystal Growth of Spin-frustrated Ba4Nb0.8Ir3.2O12: A Possible Spin Liquid Material

Thakur, G. S.; Chattopadhyay, S.; Doert, T.; Herrmannsdörfer, T.; Felser, C.

Polycrystalline Ba4NbIr3O12 has recently been shown to be a promising spin liquid candidate. We report an easy and reliable method to grow millimeter-sized single crystals of this trimer-based spin liquid candidate material with the actual stoichiometry of Ba4Nb0.8Ir3.2O12. The growth of large crystals is achieved using BaCl as flux. The crystals show a hexagonal platelike habit with edges up to 3 mm in length. The structure is confirmed by single-crystal X-ray diffraction and is found to be the same as that of the previously reported phase Ba12Nb2.4Ir9.6O36 [Ba4Nb0.8Ir3.2O12], indeed with a mixed occupancy of Nb/Ir at the 3a site. The magnetic and calorimetric study on the individual single crystals confirms the possibility of a spin liquid state consistent with a recent report on a polycrystalline sample.

Permalink: https://www.hzdr.de/publications/Publ-31014
Publ.-Id: 31014


Two-fluid model simulations of isothermal stratified counter-current flow of air and water with interface compression and turbulence damping

Tekavčič, M.; Meller, R.; Schlegel, F.; Končar, B.

Stratified flows of water and steam can appear in the primary system of a pressurized water reactor during a hypothetical loss-of-coolant accident. Among others, important safety concerns during cold water injection of the emergency core cooling system include the pressurized thermal shock and the possible formation of a condensation induced water hammer. Both mechanisms could cause significant thermal and mechanical stresses on the components of the primary system. Thorough knowledge of turbulent heat and mass transfer processes near the interface is required for safety analyses of both phenomena.
Measurements of industrially relevant turbulent two-phase flows tend to be difficult; therefore computational fluid dynamics simulations represent an important additional analytical tool. The main objective of the present research and development is to advance the capabilities of current state-of-the-art modeling tools towards the simulations of two-phase flow phenomena under realistic reactor conditions. In the present paper, the focus is on turbulence modelling near the gas liquid interface in stratified flows.
An isothermal stratified counter-current flow of air and water in a rectangular channel is simulated. Computational domain and boundary conditions are based on the flow conditions in the test section of the WENKA experiment [1]. The validation case considers supercritical stratified flow with Froude number of 2.36 and Reynolds number 12000 for water and 27000 for air.
The two-fluid modeling approach with interface compression is used to resolve the interface between the two phases. A consistent momentum interpolation numerical scheme is applied, featuring the partial elimination algorithm to handle the strong interphase drag coupling at a resolved interface. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach is used to describe turbulent two-phase flow. Modelling of turbulence dissipation at the interface requires a special treatment that includes introduction of additional turbulence damping terms into the k-ω Shear Stress Transport (SST) turbulence equations. Simulations, model and source code development are performed with the open source C++ library OpenFOAM.
Simulation results are validated with the measured profiles of volume fraction, velocity and turbulent kinetic energy at two streamwise positions in the test section of the WENKA experiment. Results of the mesh sensitivity study are presented. Furthermore, results of a parametric study reveal that an asymmetric damping approach with a lower coefficient on the liquid side of the interface can improve the prediction of turbulent kinetic energy profiles.

[1] Stäbler, T., Meyer, L., Schulenberg, T., & Laurien, E. (2006). Turbulence Structures in Horizontal Two-Phase Flows Under Counter-Current Conditions. Proceedings of FEDSM2006 (pp. 61–66). ASME.

  • Lecture (Conference)
    International Conference Nuclear Energy for New Europe NENE2020, 07.-10.09.2020, Portorož, Slovenia
  • Contribution to proceedings
    International Conference Nuclear Energy for New Europe, 07.-10.09.2020, Portorož, Slovenia,
    Two-fluid Model Simulations of Isothermal Stratified Counter-current Flow of Air and Water with Interface Compression and Turbulence Damping, 715.1-715.9

Permalink: https://www.hzdr.de/publications/Publ-31013
Publ.-Id: 31013


Fermion sign problem in path integral Monte Carlo simulations: Quantum dots, ultracold atoms, and warm dense matter

Dornheim, T.

The ab initio thermodynamic simulation of correlated Fermi systems is of central importance for many applications, such as warm dense matter, electrons in quantum dots, and ultracold atoms. Unfortunately, path integral Monte Carlo (PIMC) simulations of fermions are severely restricted by the notorious fermion sign problem (FSP). In this paper, we present a hands-on discussion of the FSP and investigate in detail its manifestation with respect to temperature, system size, interaction-strength and -type, and the dimensionality of the system. Moreover, we analyze the probability distribution of fermionic expectation values, which can be non-Gaussian and fat-tailed when the FSP is severe. As a practical application, we consider electrons and dipolar atoms in a harmonic confinement, and the uniform electron gas in the warm dense matter regime. In addition, we provide extensive PIMC data, which can be used as a reference for the development of new methods and as a benchmark for approximations.

Keywords: path integral Monte Carlo; statistical physics; sign problem; computational physics

Permalink: https://www.hzdr.de/publications/Publ-31012
Publ.-Id: 31012


Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin design

Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

These are the raw data and the processed data of the journal paper " Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin desigs".

The raw data contains the measured values on the experimental setup and the processed data contains the data of the data used in the corresponding journal publication.

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  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-10
    DOI: 10.14278/rodare.319
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31011
Publ.-Id: 31011


DNA damage in human whole blood caused by radiopharmaceuticals evaluated by the comet assay

Schmeiser, H.; Muehlbauer, K.; Mier, W.; Baranski, A.; Neels, O.; Dimitrakopolou-Strauss, A.; Schmezer, P.; Kratochwil, C.; Bruchertseifer, F.; Morgenstern, A.; Kopka, K.

Radiopharmaceuticals used for diagnosis or therapy induce DNA strand breaks, which may be detectable by single-cell gel electrophoresis (called comet assay). Blood was taken from patients before and at different time points after treatment with radiopharmaceuticals; blood cells were investigated by the comet assay using the percentage of DNA in the tail as the critical parameter. Whereas [225Ac]Ac-prostate-specific membrane antigen (PSMA)-617 alpha therapy showed no difference relative to the blood sample taken before treatment, beta therapy with [177Lu]Lu-PSMA-617 3 h post-injection revealed a small but significant increase in DNA strand breaks. In blood of patients who underwent positron emission tomography (PET) with either [18F]2-fluor-2-deoxy-D-glucose (FDG) or [68Ga]Ga-PSMA-11, an increase of DNA migration determined by the comet assay was not found when analysed at different time points (2–70 min) after intravenous tracer injection. Human whole blood was incubated with the targeted clinically relevant therapeutic radiopharmaceuticals [225Ac]Ac-PSMA-617, [177Lu]Lu-PSMA-617 and [90Y]Y-DOTA(0)-Phe(1)-Tyr(3)-octreotide (DOTA-TOC) at different activity concentrations (kBq/ml) for 5 days and then analysed by the comet assay. DNA damage increased with higher concentrations of all radiolabeled compounds tested. [177Lu]Lu-PSMA-617 caused higher blood cell radiotoxicity than equal activity concentrations of 90Y]Y-DOTATOC. Likewise, whole human blood was exposed to the positron emitters [18F]FDG and [68Ga]Ga-PSMA-11 in vitro for 24 h with activity concentrations ranging between 5 and 40 MBq/ml. The same activity concentration dependent elevated DNA migration was observed for both compounds although decay energies are different. This study demonstrated that the amount of DNA damage detected by the comet assay in whole human blood is similar among different positron emitters and divergent by a factor of 200 between alpha particles and beta radiation.

Permalink: https://www.hzdr.de/publications/Publ-31010
Publ.-Id: 31010


Using simultaneous x-ray diffraction and velocity interferometry to determine material strength in shock-compressed diamond

Macdonald, M. J.; Mcbride, E. E.; Galtier, E.; Gauthier, M.; Granados, E.; Kraus, D.; Krygier, A.; Levitan, A. L.; Mackinnon, A. J.; Nam, I.; Schumaker, W.; Sun, P.; van Driel, T. B.; Vorberger, J.; Zhou, X.; Drake, R. P.; Glenzer, S. H.; Fletcher, L. B.

We determine the strength of laser shock-compressed polycrystalline diamond at stresses above the Hugoniot elastic limit using a novel technique combining x-ray diffraction from the Linac Coherent Light Source with velocity interferometry. X-ray diffraction is used to measure lattice strains and velocity interferometry is used to infer shock and particle velocities. These measurements, combined with density-dependent elastic constants calculated using density functional theory, enable determination of material strength above the Hugoniot elastic limit. Our results indicate that diamond retains approximately 20 GPa of strength at longitudinal stresses of 150–300 GPa under shock compression.

Keywords: diffraction; diamond; strength; high pressure; shock; Hugoniot

Permalink: https://www.hzdr.de/publications/Publ-31009
Publ.-Id: 31009


Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin design

Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

In many applications finned tube bundles are commonly used for heating or cooling purpose. Hence, the natural convection heat transfer from finned heat exchanger configurations with novel design in a chimney was experimentally studied. These novel fin designs use integrated pins to enhance the heat conduction from the fin base to the fin tip as well as the convective heat transfer along the fin surface. Oval tubes with conventional circular plain fins (CPF) as well as novel circular integrated pin fins (CIPF) and serrated integrated pin fins (SIPF) were additively generated by a Selective Laser Melting (SLM) process and installed at the bottom of a 6.5 m long chimney. All heat exchanger designs were tested in a 2-row and 3-row configuration with Rayleigh numbers between 25,000 and 120,000. We found the average Nusselt number of SIPF to be higher and the Nusselt number of the CIPF to be lower compared to the CPF. Furthermore, the 2-row configuration achieved greater Nusselt number compared to the 3-row configuration for all heat exchanger designs. The analysis of the individual tube rows showed highest Nusselt numbers at the first tube row and the lowest at the last tube row for both configurations. However, for the SIPF the difference between the first and second tube row is smaller compared to the CPF and CIPF. In order to evaluate the compactness of the heat exchanger, the volumetric heat flux density was applied. Similar to Nusselt number the volumetric heat flux density enhanced for the SIPF and reduced for the CIPF compared to the conventional design. Also the 2-row configuration reaches greater thermal performance compared to the 3-row configuration. Additionally, the surface area and the volume of the heat exchanger material are 30.7 % and 6.9 % lower for the SIPF compared to the CPF. The experimental outcome was used to develop an empirical heat transfer correlation between Nusselt number, Rayleigh number, fin design and tube row number.

Keywords: Novel heat exchanger designs; Natural convection; Heat transfer performance; Additive Manufacturing; Integrated pin fin

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Permalink: https://www.hzdr.de/publications/Publ-31008
Publ.-Id: 31008


Ab initio simulation of warm dense matter

Bonitz, M.; Dornheim, T.; Moldabekov, Z. A.; Zhang, S.; Hamann, P.; Kählert, H.; Filinov, A.; Ramakrishna, K.; Vorberger, J.

Warm dense matter (WDM) { an exotic state of highly compressed matter { has attracted high interest in recent years in astrophysics and for dense laboratory systems. At the same time, this state is extremely diffcult to treat theoretically. This is due to the simultaneous appearance of quantum degeneracy, Coulomb correlations and thermal effects, as well as the overlap of plasma and condensed phases. Recent breakthroughs are due to the successful application of density functional theory (DFT) methods which, however, often lack the necessary accuracy and predictive capability for WDM applications. The situation has changed with the availability of the first ab initio data for the exchange-correlation free energy of the warm dense uniform electron gas (UEG) that were obtained by quantum Monte Carlo (QMC) simulations, for recent reviews, see Dornheim et al., Phys. Plasmas 24, 056303 (2017) and Phys. Rep. 744, 1-86 (2018). In the present article we review recent further progress in QMC simulations of the warm dense UEG: namely, ab initio results for the static local field correction G(q) and for the dynamic structure factor S(q; w). These data are of key relevance for the comparison with x-ray scattering experiments at free electron laser facilities and for the improvement of theoretical models.
In the second part of this paper we discuss simulations of WDM out of equilibrium. The theoretical approaches include Born-Oppenheimer molecular dynamics, quantum kinetic theory, timedependent DFT and hydrodynamics. Here we analyze strengths and limitations of these methods and argue that progress in WDM simulations will require a suitable combination of all methods. A particular role might be played by quantum hydrodynamics, and we concentrate on problems, recent progress, and possible improvements of this method.

Keywords: warm dense matter; first principle simulation; DFT; DFT-MD; TD-DFT; QHD; QMC; PIMC; XRTS; exchange; correlation; xc functional; response function

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Permalink: https://www.hzdr.de/publications/Publ-31007
Publ.-Id: 31007


Gallium-68 Complex of a Macrobicyclic Cage Amine Chelator Tethered to Two Integrin-Targeting Peptides for Diagnostic Tumor Imaging

Ma, M.; Neels, O.; Denoyer, D.; Roselt, P.; Karas, J.; Scanlon, D.; White, J.; Hicks, R.; Donnelly, P.

Tumor-targeting peptides radiolabeled with positron-emitting 68Ga are promising candidates as new noninvasive diagnostic agents for positron emission tomography (PET). The targeting peptides are tethered to a chelator that forms a stable coordination complex with Ga3+ that is inert to dissociation of Ga3+in vivo. Metal complexes of macrobicyclic hexaamine “sarcophagine” (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) ligands exhibit remarkable stability as a result of the encapsulating nature of the cage amine ligand. A Ga3+ sarcophagine complex, [Ga-(1-NH3-8-NH2-sar)]4+, has been characterized using X-ray crystallography, demonstrating that Ga3+ is coordinated to six nitrogen atoms in a distorted octahedral complex. A bifunctional derivative of (NH2)2sar, possessing two aliphatic linkers with carboxylic acid functional groups has been attached to two cyclic-RGD peptides that target the αvβ3 integrin receptor that is overexpressed in some types of tumor tissue. This dimeric species can be radiolabeled with 68Ga3+ in >98% radiochemical yield and 68Ga3+ does not dissociate from the ligand in the presence of transferrin, an endogenous protein with high affinity for Ga3+. Biodistribution and micro-PET imaging studies in tumor-bearing mice indicate that the tracer accumulates specifically in tumors with high integrin expression. The high tumor uptake is coupled with low nonspecific uptake and clearance predominantly through the kidneys resulting in high-quality PET images in animal models.

Permalink: https://www.hzdr.de/publications/Publ-31006
Publ.-Id: 31006


Initiierung klinischer Multicenter-Studien mit lokaler Radiotracer-Herstellung

Zippel, C.; Neels, O.; Hennrich, U.; Giesel, F.; Kopka, K.

Ziel des Aufsatzes ist es, wesentliche gesetzliche und regulatorische Aspekte zu beleuchten, die bei multizentrischen klinischen Prüfungen mit kurzlebigen PSMA-PET-Radiopharmaka im Hinblick auf die Etablierung einer dezentralen Herstellung des klinischen Prüfpräparats zu beachten sind. Solche prospektiven Studien spielen in der nuklearmedizinischen Forschung und Entwicklung eine zunehmend wichtige Rolle. Um PSMA-PET-Tracer mit kurzer Halbwertzeit für die Prostatakrebsdiagnostik weiter im behördlichen Zulassungsverfahren und schließlich im Gesundheitssystem etablieren zu können, schließen sich nuklearmedizinische Zentren zunehmend standortübergreifend zusammen, um in angemessener Zeit hierfür die notwendige Anzahl von Studienpatienten zu erreichen. Im Folgenden gehen wir auf das regulatorische Umfeld zur Herstellung von PSMA-PET-Radiopharmaka als klinisches Prüfpräparat (engl. Investigational Medicinal Product, IMP) ein, und führen am Beispiel der frühen multizentrischen klinischen Prüfung der Phasen-I und -II „[68Ga]Ga-PSMA-11 in high-risk Prostate Cancer“ wesentliche Aspekte an, die bei der Initiierung einer prospektiven Studie mit dezentraler PSMA-Tracer-Herstellung aus radiopharmazeutisch-organisatorischer Sicht zu berücksichtigen und im Vorfeld abzustimmen sind.

Keywords: Radiopharmaka-Herstellung; gute Herstellungspraxis; PSMA-Tracer; multizentrische Studie; prospektive klinische Prüfung; Qualitätsmanagement

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Permalink: https://www.hzdr.de/publications/Publ-31005
Publ.-Id: 31005


Impact of 18F-PSMA-1007 Uptake in Prostate Cancer Using Different Peptide Concentrations: Preclinical PET/CT Study on Mice

Soeda, F.; Watabe, T.; Naka, S.; Liu, Y.; Horitsugi, G.; Neels, O.; Kopka, K.; Tatsumi, M.; Shimosegawa, E.; Giesel, F.; Hatazawa, J.

PET radioligands with low molar activity (MA) may underestimate the quantity of the target of interest because of competitive binding of the target with unlabeled ligand. The aim of this study was to evaluate the change in the whole-body distribution of 18F-PSMA-1007 targeting prostate-specific membrane antigen (PSMA) when solutions with different peptide concentrations are used. Methods: Mouse xenograft models of LNCaP (PSMA-positive prostate cancer) (n = 18) were prepared and divided into 3 groups according to the peptide concentration injected: a high-MA group (1,013 ± 146 GBq/μmol; n = 6), a medium-MA group (100.7 ± 23.1 GBq/μmol; n 5 6), and a low-MA group (10.80 ± 2.84 GBq/μmol; n = 6). Static PET scans were performed 1 h after injection (scan duration, 10 min). SUVmean in tumor and normal organs was compared by the multiple-comparison test. Immunohistochemical staining and Western blot analysis were performed to confirm expression of PSMA in tumor, salivary gland, and kidney. Results: The low-MA group (SUVmean, 1.12 ± 0.30) showed significantly lower uptake of 18F-PSMA-1007 in tumor than did the high-MA group (1.97 ± 0.77) and the medium-MA group (1.81 ± 0.57). On the other hand, in salivary gland, both the low-MA group (SUVmean, 0.24 ± 0.04) and the medium-MA group (0.57 ± 0.08) showed significantly lower uptake than the high MA group (1.27 ± 0.28). The tumor-to-salivary gland SUVmean ratio was 1.73 ± 0.55 in the high-MA group, 3.16 ± 0.86 in the medium-MA group, and 4.78 ± 1.29 in the low-MA group. The immunohistochemical staining and Western blot analysis revealed significant overexpression of PSMA in tumor and low expression in salivary gland and kidney. Conclusion: A decrease in the MA level of the injected 18F-PSMA-1007 solution resulted in decreased uptake in tumor and, to a greater degree, in normal salivary gland. Thus, there is a possibility of minimizing the adverse effects in salivary gland by setting an appropriate MA level in PSMA targeting therapy.

Keywords: 18F-PSMA-1007; peptide concentration; molar activity; prostate cancer; salivary gland

  • Open Access Logo Journal of Nuclear Medicine 60(2019), 1594-1599
    DOI: 10.2967/jnumed.118.223479
  • Lecture (Conference)
    Annual Congress of the European Association of Nuclear Medicine, October 13 – 17, 2018, Düsseldorf, Germany, 13.-17.10.2018, Düsseldorf, Deutschland
    DOI: 10.1007/s00259-018-4148-3

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Publ.-Id: 31004


Production of Ga-68 radiotracers under GMP and regulatory aspects - a German perspective

Neels, O.

Radiopharmaceuticals labelled with the positron emitter Gallium-68 have had an enormous impact on the diagnostic imaging of neuroendocrine tumors using somatostatin receptor ligands and in recent years on the diagnosis of prostate cancer using PSMA ligands and subsequently their application for radioendotherapy using Yttrium-90, Lutetium-177 or more recently Actinium-225. The release of the monographs for ‘Gallium-68 chloride solution for radiolabelling’ and ‘Gallium-68 Edotreotide injection’ within the European Pharmacopoeia in 2013 tightened the requirements for specifications of Gallium-68 labelled radiotracers and will be enhanced with the ongoing elaboration of monographs for ‘Gallium-68 DOTA-TATE injection’, ‘Gallium-68 DOTA-NOC injection’ and ‘68Ga-PSMA’. In the same way the work environment of the responsible radiochemists and radiopharmacists in terms of quality control has been improved but also the workload has reached a high level with the increasing number of clinical applications and the limitation of the maximum achievable amount of starting activity from the currently available generators and therefore a limited dose number. The change of conditions for the production and quality control of Gallium-68 labelled radiopharmaceuticals will be reviewed with regards to legislating and practical aspects from ‘on bench’ to ‘full GMP’ preparation linked to the specific requirements for a multi-centre clinical trial using 68Ga-PSMA-11 in high-risk prostate cancer.

  • Open Access Logo Invited lecture (Conferences)
    4th Theranostics World Congress 2016, 07.-09.11.2016, Melbourne, Australia
    DOI: 10.1530/endoabs.47.OC2

Permalink: https://www.hzdr.de/publications/Publ-31003
Publ.-Id: 31003


Thermal kinetics of free volume in porous spin-on dielectrics: exploring the network- and pore-properties

Elsherif, A. G. A.; Koehler, N.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Ecke, R.; Schulz, S. E.; Wagner, A.

Data to ULK-kinetics by Positron annihilation spectroscopy and Fourier transform infrared spectroscopy

Keywords: PALS, FTIR, ULK, Curing

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-05-11
    DOI: 10.14278/rodare.321
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31002
Publ.-Id: 31002


Manipulation of [11C]-5-Hydroxytryptophan and 6-[18F]Fluoro-3,4-Dihydroxy-L-Phenylalanine Accumulation in Neuroendocrine Tumor Cells

Neels, O.; Koopmans, K.; Jager, P.; Vercauteren, L.; van Waarde, A.; Doorduin, J.; Timmer-Bosscha, H.; Brouwers, A.; de Vries, E.; Dierckx, R.; Kema, I.; Elsinga, P.

[11C]-5-Hydroxytryptophan ([11C]HTP) and 6-[18F]fluoro-3,4-dihydroxy-L-phenylalanine ([18F]FDOPA) are used to image neuroendocrine tumors with positron emission tomography. The precise mechanism by which these tracers accumulate in tumor cells is unknown. We aimed to study tracer uptake via large amino acid transporters, peripheral decarboxylation (inhibited by carbidopa), and intracellular breakdown by monoamine oxidase (MAO). [11C]HTP and [18F]FDOPA tracer accumulation was assessed in a human neuroendocrine tumor cell line, BON. The carbidopa experiments were done in a tumor-bearing mouse model. Intracellular [11C]HTP accumulation was 2-fold higher than that of [18F]FDOPA. Cellular transport of both tracers was inhibited by amino-2-norbornanecarboxylic acid. The MAO inhibitors clorgyline and pargyline increased tracer accumulation in vitro. Carbidopa did not influence tracer accumulation in vitro but improved tumor imaging in vivo. Despite lower accumulation in vitro, visualization of [18F]FDOPA is superior to [11C]HTP in the neuroendocrine pancreatic tumor xenograft model. This could be a consequence of the serotonin saturation of BON cells in the in vivo model.

Permalink: https://www.hzdr.de/publications/Publ-31001
Publ.-Id: 31001


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