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43562 Publications

Production and Dosimetry: Possible Application of 133La in the Clinic

Brühlmann, S. A.; Walther, M.; Blei, M. K.; Mamat, C.; Kopka, K.; Freudenberg, R.; Kreller, M.

Abstract

Aim: Actinium-225 plays a key role in targeted alpha therapy, nevertheless, depending on the chelating system, no real diagnostic surrogate for actinium has been established. Lanthanum-133 has been proposed due to their chemical similarities and attractive decay properties (7.2% β+, Eβ,mean=461 keV, T1/2=3.91 h) [1,2]. However, main concerns about this radionuclide production scalability and its associated dosimetry may rise, due to its long-lived daughter 133Ba (T1/2=10.5 y).

Methods: The radiometal 133La was produced via the 134Ba(p,2n)133La nuclear reaction using the HZDR TR-Flex (ACSI) cyclotron (18.7 MeV, 60 µA, 15-120 min). The irradiated targets, silver or aluminum disks filled with 25 mg of [134Ba]BaCO3 and covered with aluminum foils, were opened up, the solid powder separated mechanically and dissolved in HNO3. Four commercially available chromatography resins based on diglycolamide and phosphine oxide groups were tested for the one-step radiochemical purification. The product was analyzed in terms of radionuclide purity (RNP) by gamma spectroscopy and radiochemical purity by titration with the macropa chelator. Test radiolabeling of PSMA-617 and macropa-derived PSMA ligand previously published by our group, namely mcp-M-PSMA, was performed in the GBq/µmol range. Furthermore, the activities required for human PET acquisition and initial dosimetry calculations were estimated using the IDAC-Dose 2.1 software.

Results: The study demonstrated the scalability of the production method, with activities of up to 10.7 GBq of 133La produced at the end of bombardment. Four chromatographic resins were tested, with an optimized purification method reaching a recovery efficiency of over 98% and a decay-corrected 133La recovery efficiency of over 98% in approximately 20 minutes. High RNP and apparent molar activity (AMA) were quantified, of over 99.5% and 120 GBq/µmol, respectively, at end of purification. Furthermore, quantitative complexation of PSMA-617 and mcp-M-PSMA was obtained with molar activities reaching up to 80 GBq/µmol (90 °C, 30 min). In addition, it was determined that a 133La activity in the 350 MBq to 750 MBq range would be necessary for human PET imaging. This activity injected would lead to a one-year effective dose of 2.1-4.4 mSv, which is comparable to that of 18F- and 68Ga-based radiopharmaceuticals.

Conclusion: A comprehensive study on 133La production was conducted at the HZDR. The study commenced with the optimization of irradiation parameters and radiochemical purification studies, resulting in the production of a high-quality product with regard to RNP and AMA. Furthermore, the radiolabeling of PSMA ligands with the produced [133La]LaCl3 was successfully carried out. Additionally, preliminary dosimetry estimations demonstrated the viability of using this radionuclide for PET acquisition in patients.

References:

[1] Nelson BJ, Wilson J, et al. Scientific Reports 2020, 10, 1, 22203.
[2] Brühlmann SA, Kreller M, et al. Pharmaceuticals 2022, 15, 1167.

  • Lecture (Conference)
    30. Jahrestagung der AG Radiochemie/Radiopharmazie der DGN, 19.-21.09.2024, Mannheim, Germany

Permalink: https://www.hzdr.de/publications/Publ-40276


East vs West: comparing the rates of landscape change in the southern African region.

Khosa, R.; Tooth, S.; Pickering, R.; Mbele, V.; Winkler, S.; Stübner, K.

Abstract

For channel incision rate determination and comparison, bedrock samples from sections of the Olifants River (n = 10) in the dry tropical/subtropical Kruger National Park, as well as samples from sections of the Orange River (n = 20), in the arid Northern Cape were collected. Using cosmogenic in-situ 10Be in pure quartz, average incision rates determined from granitic samples of the Olifants River indicate that the channel is incising at a rate of 26.4 ± 1.77 m/Ma, while granitic and quartzitic samples from along the Orange River produce a slower average rate of 6.89 ± 0.45 m/Ma, implying considerably slower channel evolution in the west. These rates fall within a very wide range of previously determined rates of erosion and channel incision across various southern Africa of 0.2 – 255 m/Ma landforms. The roughly four times faster channel incision rate along the Olifants River, compared to that of the Orange River, suggest that the prevailing long-term climate is a driver on erosion and apparent exposure ages, where the wetter east yields faster rates and younger apparent exposure ages, while the drier west, slower rates and older apparent exposure ages. Quartzitic rates of incision are also seen to be slower than those of granitic composition along the Orange River, suggesting a further lithological control on the rates of erosion and landscape change. Although the southern African landscape has been considered tectonically quiescent, the data presented here imply that landscape evolution is not uniform, and that is prevailing long-term climate variability and lithology are the primary drivers of differential erosion across the region.

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  • Poster
    16th International Conference on Accelerator Mass Spectrometry, 21.-26.10.2024, Guilin, China

Permalink: https://www.hzdr.de/publications/Publ-40275


Temperature-Dependent Dynamics of Charge Carriers in Tellurium Hyperdoped Silicon

Ashikur Rahman, K.; Saif Shaikh, M.; Yue, Q.; Senali Dissanayake, S.; Wang, M.; Zhou, S.; Sher, M.-J.

Abstract

Tellurium-hyperdoped silicon (Si:Te) shows significant promise as an intermediate band material candidate for highly efficient solar cells and photodetectors. Time-resolved THz spectroscopy (TRTS) is used to study the excited carrier dynamics of Si hyperdoped with 0.5, 1, and 2%. The two photoexcitation wavelengths enable us to understand the temperature-dependent carrier transport in the hyperdoped region in comparison with the Si region. Temperature significantly influences the magnitude of transient conductivity and decay time when photoexcited by light with a wavelength of 400 nm. Due to the differential mobilities in the Si and hyperdoped regions, such dependence is absent under 266-nm excitation. Consistent with the literature, the charge-carrier lifetime decreases with increasing dopant concentration. It is found that the photoconductivity becomes less temperature-dependent as the dopant concentration increases. In the literature, the photodetection range of Si:Te extends to a wavelength of 5.0 µm at a temperature of 20 K. The simulation shows that carrier diffusion, driven by concentration gradients, is strongly temperature dependent and impacts transient photoconductivity decay curves. The simulation also revealed that, in the hyperdoped regions, the carrier recombination rate remains independent of temperature.

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Permalink: https://www.hzdr.de/publications/Publ-40274


Current Status on [64Cu]CuCl2 Production with a TR-Flex Cyclotron at the HZDR

Walther, M.; Brühlmann, S. A.; Kopka, K.; Kreller, M.

Abstract

Abstract. In recent years, interest in 64Cu-based radiopharmaceuticals has raised. Therefore, upscaling concept for the production of this radionuclide is of huge interest to meet its increasing demand. At the HZDR we have a weekly [64Cu]CuCl2 routine production, which intends to satisfy both internal as well as external requests. 64Cu is produced by proton irradiation of 64Ni electroplated targets and separated with the well-known anion exchange method. Activities in the tens of GBq range are usually produced, depending the demand.

1. Introduction. 64Cu has found an important role in the radiopharmaceutical sciences due to its attractive positron-emission decay properties. In particular, there is even an already FDA-approved radiopharmaceutical, DetectnetTM [1]. Furthermore, the main production route for this radionuclide is based on the 64Ni(p,n)64Cu nuclear reaction, suitable for compact cyclotrons. We discuss here the current status of our 64Cu scaled-up production based on solid targetry with a focus in the product characterization.
2. Method & Materials. Target production follows 64Ni electrodeposition onto gold foils or discs, obtaining masses in the 40-110 mg range. Such targets are irradiated using the 90° solid target configuration of the HZDR TR-Flex cyclotron with (13.0 ± 0.2) MeV protons at a 35-70 µA current for 90 to 180 min, depending on the 64Cu demand. After irradiation, the radiocopper purification is performed via the anion exchanger method, based on a 2 mL pre-packed AG-1x8 anion exchanger [2]. The apparent molar activity (AMA) of the product [64Cu]CuCl2 is estimated by titration with the macrocyclic complexing agent TETA (1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid. Moreover, after separation the major nickel-fraction is collected and re-used for further electroplating.
3. Results & Discussion. 64Cu activities between 10 and 55 GBq at end of bombardment (EOB) have been produced, which after purification result in 6 to 35 GBq of a ready-to-label [64Cu]CuCl2 solution. Test radiolabeling usually proves AMA of over 1000 GBq/µmol. Furthermore, radionuclidic impurity cannot be quantified shortly after and up to 96 hours after purification. In Figure 1, a gammaspectrum of the [64Cu]CuCl2 product is presented.

Figure 1: Gammaspectroscopy of [64Cu]CuCl2 within 1-hour after purification.
4. Conclusion. Our routine production of 64Cu leads to activities in the tens of GBq. Moreover, the achieved [64Cu]CuCl2 solution (pH 1-3, activity concentration 10-60 MBq/mL) demonstrates a high AMA and a high radionuclide purity, over 1 TBq/µmol and 99.5%, respectively. Further studies investigating the 30° solid target configuration at the TR-Flex cyclotron to increase the 64Cu yield and its molar activity are currently being performed.
References.
1. de la Torre, B.G.; Albericio, F. Molecules 2021, 26, 627.
2. Thieme, S.; Walther, M.; Pietzsch, H. J.; Henniger, J.; Preusche, S.; Mäding, P.; Steinbach, J. Appl rad isot 2012, 70(4), 602-608.

  • Lecture (Conference)
    19th International Workshop on Targetry and Target Chemistry, 25.-30.08.2024, Heidelberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-40273


Routine Production of [67Cu]CuCl2 at the TR-Flex Cyclotron: Report on Challenges Faced and Potential Solutions

Brühlmann, S. A.; Walther, M.; Kopka, K.; Kreller, M.

Abstract

Abstract. Copper-67 has been produced at the HZDR on a semimonthly basis since end of 2022. Basically, proton irradiation of enriched 70Zn electroplated targets onto silver substrates has been performed. Two radiochemical purification methods have been developed. The obtained [67Cu]CuCl2 product shows high radionuclidic purity and apparent molar activity.
1. Introduction. Theranostic 67Cu has aroused interest in the radiopharmaceutical community due to its decay properties. However, the lack of availability of this radionuclide prevents the full exploitation of therapeutic copper-based radiopharmaceuticals. The 68Zn(γ,p)67Cu photonuclear reaction has proved comparable high yields and quality in commercial scale [1]. Nevertheless, an attractive alternative is the in-house production of this radionuclide via the 70Zn(p,α)67Cu nuclear reaction at a compact cyclotron. In this work we discuss the challenges faced by [67Cu]CuCl2 routine production and our approach to establish its reliably availability to enable further development of copper-based radiopharmaceuticals.
2. Method & Materials. 70Zn (120-160 mg) is electrodeposited onto rectangular silver backings and irradiated by protons (16.8 MeV proton beams / 60 µA target current) using the 30° solid target configuration of the HZDR TR-Flex cyclotron for up to 20 h, split into 2 days: 7 h and 13 h, respectively. Radiochemical separation is performed based on a CU resin as previously described [2] or with an alternative method based on the anion exchange resin AG-1x8. Radionuclidic purity (RNP) of the product 67Cu is characterized by gammaspectroscopy while apparent molar activity (AMA) is determined by titration of the [67Cu]CuCl2 solution with the complexing agent 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid. Target recycling is performed by [70Zn]Zn(OH)2 precipitation and subsequent electroplating [2].
3. Results & Discussion. 67Cu activities of up to 1.10 GBq at end of bombardment (EOB) have been produced, translated to over 800 MBq of [67Cu]CuCl2 at end of purification (EOP). After long irradiations (accumulated charge over 1000 µAh), the silver backing started to exhibit blisters, which were gas-filled. Monitoring of the silver backings and their evolution will be performed in the future. Moreover, the product fraction is obtained in 2 mL of diluted (0.01-0.05 M) HCl regardless of the method used for the separation. Furthermore, the method based on the AG-1x8 resin allowed the faster radiochemical separation avoiding the neutralization needed for the CU resin. RNP of over 99.5 % at EOP has been quantified, and only 61Cu and 64Cu impurities detected, <0.03% and <0.3%, respectively. AMA of over 100 GBq/µmol at EOP is usually determined. Target recycling is successfully being performed, with a 70Zn recovery yield of over 90 % [2].
4. Conclusion. Copper-67 activities in the 500-1100 MBq range are produced on a semimonthly basis at the HZDR for over 1.5 year. Challenges regarding the target backing and the radiochemical purification have been identified and will be furtheron be solved.
Acknowledgments. We would like to thank Steffen Happel from Triskem for providing the different resins used and the HZDR TR-Flex team for performing the long irradiations.
References.
1. Stoner J., Gardner T. PRODUCTION OF COPPER-67 FROM AN ENRICHED ZINC-68 TARGET. US 2018 / 0209013 A1. 2018.
2. Brühlmann, S.A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Kniess, T.; Kopka, K. Pharmaceuticals 2023, 16, 314.

  • Open Access Logo Lecture (Conference)
    19th International Workshop on Targetry and Target Chemistry, 25.-30.08.2024, Heidelberg, Germany

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Permalink: https://www.hzdr.de/publications/Publ-40272


An alternative production route for the PET radionuclide 61Cu: exploring the 62Ni(p,2n)61Cu nuclear reaction

Brühlmann, S. A.; Walther, M.; Kopka, K.; Kreller, M.

Abstract

Background
True theranostic matched pairs of radionuclides are a topic of high interest in the radiopharmaceutical sciences. From the handful of true matched radionuclides, the radiocopper trio 61Cu, 64Cu and 67Cu, for diagnosis through PET and endoradiotherapy, respectively, stands out due to its simple chemistry and favorable physical properties. Furthermore, the high availability of 64Cu has enabled huge developmental projects of copper-based radiopharmaceuticals [1]. Nevertheless, a shorter-lived PET radionuclide such as 61Cu may as well be beneficial. Currently, 61Cu is being produced either from 61Ni, 64Zn or natZn, however, we present here our results on the production via the 62Ni(p,2n)61Cu nuclear reaction.
Material and methods
Thick nickel electrodepositions (130-260 mg/cm2) were performed from [62Ni][Ni(NH3)6]SO4 solutions (fresh metallic 62Ni ingots or recycled [62Ni]NiCl2, pH 9, I=26 mA) onto gold backings, similar as already described by our group for 64Ni [2]. These targets were irradiated at our TR-Flex (ACSI) cyclotron, with an incident proton energy of 20-22 MeV (target mass-dependent) and 70 µA current for 1 h. After a 1 h decay to reduce the also occurring 62Cu activity, radiochemical purification was performed by a one-step separation based on a 2 mL AG-1x8 column or a 1 mL TK201 cartridge, respectively. The radiocopper elution was performed with H2O or 0.01 M HCl, respectively. Aliquots of the nickel, cobalt and copper fractions were analyzed by gamma-spectroscopy means. Apparent molar activities (AMA) of the solution were determined by titration of the [61Cu]CuCl2 fraction with the macrocyclic complexing agent 1,4,8,11-Tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA) in combination with radio-TLC.
Results
Saturation yields of 800-1500 MBq/µA were quantified, representing 25 % of the theoretical ones.
Copper-61 activities of up to 20 GBq at EOB were quantified, which was translated to up to 8 GBq at end of purification (EOP) contained in 2 mL 1.5 M HCl (which could be dried and re-dissolved in 700 µL H2O) or in 2 mL 0.01 M HCl, depending on the separation method. Both alternatives lead to comparable results regarding separation yield and product purity. The [61Cu]CuCl2 solution proved radionuclidic purities over 99 % and AMA of 260 GBq/µmol with the TETA chelator, EOP corrected.
Conclusions
We present here a comprehensive novel production method for the PET radionuclide 61Cu as alternative to the most popular production routes. Characterization of the [61Cu]CuCl2 product showed both high RNP as well as high AMA up to 9 h after EOP. Furthermore, production scalability could be easily achieved by increasing the irradiation time.
References
[1] IAEA. Copper-64 radiopharmaceuticals: Production, quality control and clinical applications. Vienna, Austria: IAEA; 2023.
[2] Thieme S, Walther M, Pietzsch H-J, Henniger J, Preusche S, Mäding P, Steinbach J (2012) Module-assisted preparation of 64Cu with high specific activity. Applied Radiation and Isotopes 70:602–608.

  • Contribution to proceedings
    21st European Symposium on Radiopharmacy & Radiopharmaceuticals, 18.-21.04.2024, Coimbra, Portugal

Permalink: https://www.hzdr.de/publications/Publ-40271


The radiocopper trio: cyclotron production of the true theranostic matched radionuclides 61/64Cu and 67Cu

Brühlmann, S. A.; Walther, M.; Kopka, K.; Kreller, M.

Abstract

Ziel/Aim: Theranostic matched pairs of radionuclides have aroused interest in the last couple of years. There are only a handful of true theranostic matched radionuclides, and in particular the radiocopper trio 61/64Cu (low-energy β+-emitters, 3.34 h and 12.70 h half-lives, respectively) and 67Cu (low-energy β--emitter, 61.83 h), are a very attractive alternative [1]. Therefore, a comprehensive method for routine production of these copper radioisotopes has been developed and is being optimized at the HZDR.
Methodik/Methods: Targets are produced by enriched 62/64Ni and 70Zn electrodeposition, for 61/64Cu and 67Cu production, respectively. Proton irradiation of the targets is performed with the HZDR TR-FLEX (ACSI) cyclotron, with optimized parameters from simulations and test irradiations (20, 13.5 & 17 MeV; 60, 60 & 70 µA; 1, 2, 16 h, respectively). Radiochemical purification follows the procedure already described by our group [2,3], although further chromatographic resin-based methods are under investigation. Quality assessment of the obtained [61/64/67Cu]CuCl2 solutions is performed to quantify radionuclidic purity, RNP, and apparent molar activity, AMA.
Ergebnisse/Results: Activities of up to 6, 35 and 0.8 GBq, for 61Cu, 64Cu and 67Cu, respectively, have been achieved. Furthermore, longer irradiation times up to one half-life would lead to even higher activities. A RNP of over 99.5 % at end of purification, and AMAs of over 250, 1500 and 150 GBq/µmol were quantified, thus presenting a comparable quality to that of commercially available radionuclides, e.g. 68Ga.
Schlussfolgerungen/Conclusions: The availability of the theranostic matched radionuclides 61Cu/64Cu/67Cu plays a primordial role in order to allow further development of radiocopper-based radiopharmaceuticals. At the HZDR, 64Cu has been produced since 2007, 67Cu since 2022 and 61Cu production is being re-established by end of 2023. Currently, the produced radiocopper is being used for in vitro and in vivo experiments.
Literatur/Literature:
[1] Wadas et al. Curr Pharm Des 2007, 13, 1, 3-16
[2] Thieme et al. Appl Radiat Isot 2012, 70, 4, 602–608
[3] Brühlmann et al. Pharmaceuticals 2023, 16, 314

  • Open Access Logo Contribution to proceedings
    62. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 10.-13.04.2024, Leipzig, Germany

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Permalink: https://www.hzdr.de/publications/Publ-40270


Einfluss von Al auf die Rückhaltung von dreiwertigen Aktiniden an Feldspat.

Lessing, J.; Neumann, J.; Hennig, C.; Eng, P.; Stubbs, J.; Brendler, V.; Schmidt, M.; Stumpf, T.

Abstract

Bei der Endlagerung radioaktiver Abfälle in tiefen geologischen Formationen ist die geologische Barriere für eine Million Jahre perspektivisch das wesentlichste Element im Safety Case. Im Kristallin ist dabei die Rückhaltung dreiwertiger Actiniden an Feldspäten (Hauptkomponenten in Granit, Granodiorite und Gneiss) noch nicht verlässlich beschreibbar. Dies betrifft z. B. die Konkurrenzsituation von aus Feldspäten gelösten Kationen (namentlich Al3+) mit den Radionukliden um Sorptionsplätze, aber auch die generell variablen Lösungszusammensetzungen sowie Oberflächen-charakteristika der Feldspäte.
Hier untersuchen wir den Einfluss von wässrigen Aluminiumspezies auf das Sorptionsverhalten von dreiwertigen Actiniden und Lanthaniden an Orthoklas, einem Kalium haltigen Feldspat, um die Unterschiede im Sorptionsverhalten dieser Elemente an Feldspäten zu verstehen. Die Charakterisierung der Oberflächenladung zeigt einen starken Anstieg des Zetapotenzials (zunächst eine geringeres negatives Zetapotenzial in absolute Zahlen) und sogar eine Ladungsumkehr (von negativ nach positiv) zwischen pH 4,5 – 7 für Ca-Feldspäte. Dieses Verhalten wird für unbehandelten K Feldspat nicht beobachtet, wird aber durch Hinzufügen von Al3+ zur wässrigen Phase erhalten. Die Bildung einer potenziellen sekundären Phase wird durch Raman-Spektroskopie, Synchrotron-Pulver-Röntgendiffraktion (XRD) und hochauflösender Oberflächen-Röntgenbeugung untersucht. Demnach wird kein kristallines Al3+-Präzipitat auf der Oberfläche gebildet. Stattdessen wird Al3+ an der Oberfläche des Minerals adsorbiert und ändert dort u. a. auch die Wasserstruktur, was die Aufnahme der Actiniden beeinflusst.

Keywords: Feldspat; Aluminium; Sekundärphasen

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  • Lecture (Conference)
    Jahrestagung der Fachgruppe Nuklearchemie 2024, 05.-07.11.2024, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40269


Influence of Al on the Retention of Trivalent Actinides and their Homologues in Feldspar.

Lessing, J.; Neumann, J.; Bok, F.; Lützenkirchen, J.; Brendler, V.; Schmidt, M.; Stumpf, T.; Hennig, C.; Eng, P.; Stubbs, J.

Abstract

To effectively select a final repository for radioactive waste, understanding the interactions between radionuclides and the repositories’ barriers is essential. Crystalline rock is considered a possible host rock, the last barrier of a final disposal in a deep geological repository. Crystalline rock mainly consists of alumino silicates, such as feldspars and mica, as well as quartz.
This study focuses on the interaction of trivalent minor actinides, which, along with plutonium, contribute significantly to the radiotoxicity of spent nuclear fuel over geological time scales. Besides the minor actinides Am(III) and Cm(III), we use Eu(III) and Y(III) as homologue due to their similar chemical properties.
Recent findings indicate that An(III) are effectively immobilized on feldspars [1] and that this immobilization is more pronounced on calcium-rich feldspars compared to alkali-rich ones. This difference is related to unusual charge reversal phenomena, which were observed through streaming and zeta potential measurements. This reversal is potentially attributable to the stronger dissolution of these minerals, which increases the concentration of Al(III) in the surrounding solution. Experimentally, adding Al(III) ion containing aqueous solutions to feldspars which are low in calcium content has successfully replicated these surface charge reversals [2].
The current study aims to reach deeper insights into the molecular mechanisms affecting the interaction between aluminum and the feldspar surface, and how this interaction subsequently influences the sorption of An(III)/Ln(III) ions. Techniques such as synchrotron powder X-ray diffraction (XRD) and high-resolution X-ray reflectivity are employed to examine secondary phases that might form on the mineral surfaces as a result of these processes. This shall advance the understanding of physico-chemical processes relevant for nuclear waste management and improve the safety and efficiency of long-term disposal strategies.

Keywords: Feldspar; Aluminum; Secondary Phases

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  • Lecture (Conference)
    ACS Spring 2024, 17.-21.03.2024, New Orleans, USA
  • Lecture (Conference)
    10th International Conference on Nuclear and Radiochemistry – NRC10, 25.-30.08.2024, Brighton, UK

Permalink: https://www.hzdr.de/publications/Publ-40268


On the Physical Consistency of an Open Quantum Region with a Classical Reservoir in Molecular Simulation

Panahian Jand, S.; Kühne, T. D.-S.; Delle Site, L.

Abstract

The possibility of treating a molecular liquid in an open region at ab initio electronic resolution embedded in a classical reservoir of energy and particles, is investigated. Because of its challenging properties and its relevance in many field of current research, the system chosen as prototype of molecular liquid is water at room conditions. A numerical protocol based on the mathematical model of open particle system is applied and the results are compared with results of a full ab initio simulation of reference. The key conclusion is that one can claim the existence of a mandatory minimal size of the quantum region in which structural and electronic properties reproduce those of reference and, at the same time, the exchange of molecules with the environment takes place as expected. This work provides a proof of concept about the possibility to systematically define a physically well founded open quantum system embedded in a classical environment. In turn, the proof of concept is a key information for the design of numerically efficient algorithms for ab initio molecular dynamics simulations of open systems.

Permalink: https://www.hzdr.de/publications/Publ-40266


A new sensor concept to localize non-conducting void fractions in liquid metal based on the measured magnetic field

Krause, L.; Kumar, N.; Gumhold, S.; Eckert, K.; Eckert, S.; Wondrak, T.

Abstract

Electrolytically produced hydrogen using renewable energy is a key energy carrier in transitioning to green energy. Hydrogen and oxygen as the desired products are evolving in form of gas bubbles during water electrolysis upon application of a current. However, the gas bubbles are not electrically con-ductive, block electrocatalytically active surface on the electrodes during their growth and thus reduce the overall efficiency [1]. Measurement techniques such as X-ray tomography can localize the gas bub-bles [2], but the process to implement them in indus-trial electrolyzers is complex. Information about the distribution of electrical conductivity σ can be derived from the magnetic field generated outside the elec-trolyzer by the current inside the cell. Gradients of σ, such as those between electrolyte solution and gas bubbles, modify the distribution of the electric cur-rent density j, whose structure determine the shape of the magnetic flux density B. This study proposes a new method that is easily in-stallable, non-intrusive and reconstructs the conduc-tivity distribution within the cell based on B meas-urements, thus enabling the localization of non-conductive fractions.

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  • Data Center
  • Lecture (Conference)
    17. Dresdner Sensor-Symposium, 25.-27.11.2024, Dresden, Deutschland
  • Open Access Logo Contribution to proceedings
    17. Dresdner Sensor-Symposium, 25.-27.11.2024, Dresden, Deutschland
    DOI: 10.5162/17dss2024/2.3

Permalink: https://www.hzdr.de/publications/Publ-40265


Projective Spin Adaptation for the Exact Diagonalization of Isotropic Spin Clusters

Ghassemi Tabrizi, S.; Kühne, T. D.-S.

Abstract

Spin Hamiltonians, like the Heisenberg model, are used to describe the magnetic properties of exchange-coupled molecules and solids. For finite clusters, physical quantities, such as heat capacities, magnetic susceptibilities or neutron-scattering spectra, can be calculated based on energies and eigenstates obtained by exact diagonalization (ED). Utilizing spin-rotational symmetry SU(2) to factor the Hamiltonian with respect to total spin S facilitates ED, but the conventional approach to spin-adapting the basis is more intricate than selecting states with a given magnetic quantum number M (the spin z-component), as it relies on irreducible tensor-operator techniques and spin-coupling coefficients. Here, we present a simpler technique based on applying a spin projector to uncoupled basis states. As an alternative to Löwdin’s projection operator, we consider a group-theoretical formulation of the projector, which can be evaluated either exactly or approximately using an integration grid. An important aspect is the choice of uncoupled basis states. We present an extension of Löwdin’s theorem for s=12 to arbitrary local spin quantum numbers s, which allows for the direct selection of configurations that span a complete, linearly independent basis in an S sector upon the spin projection. We illustrate the procedure with a few examples.

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Permalink: https://www.hzdr.de/publications/Publ-40264


Tuning the Permeation Properties of Poly(1-trimethylsilyl-1-propyne) by Vapor Phase Infiltration Using Trimethylaluminum

Jenderny, J.; Boysen, N.; Rubner, J.; Zysk, F.; Preischel, F.; de los Arcos, T.; Damerla, V. R.; Kostka, A.; Franke, J.; Dahlmann, R.; Kühne, T. D.-S.; Wessling, M.; Awakowicz, P.; Devi, A.

Abstract

Vapor phase infiltration (VPI) has emerged as a promising tool for fabrication of novel hybrid materials. In the field of polymeric gas separation membranes, a beneficial impact on stability and membrane performance is known for several polymers with differing functional groups. This study for the first time investigates VPI of trimethylaluminum (TMA) into poly(1-trimethylsilyl-1-propyne) (PTMSP), featuring a carbon–carbon double bond as functional group. Saturation of the precursor inside the polymer is already attained after 60 s infiltration time leading to significant densification of the material. Depth profiling proves accumulation of aluminum in the polymer itself, but a significantly increased accumulation is visible in the gradient layer between polymer and SiO2 substrate. A reaction pathway is proposed and supplemented by density-functional theory (DFT) calculations. Infrared spectra derived from both experiments and simulation support the presented reaction pathway. In terms of permeance, a favorable impact on selectivity is observed for infiltration times up to 1 s. Longer infiltration times yield greatly reduced permeance values close or even below the detection limit of the measurement device. The present results of this study set a strong basis for the application of VPI on polymers for gas-barrier and membrane applications in the future.

Permalink: https://www.hzdr.de/publications/Publ-40263


Ultrafast Two-Color X-Ray Emission Spectroscopy Reveals Excited State Landscape in a Base Metal Dyad

Nowakowski, M.; Huber-Gedert, M.; Elgabarty, H.; Kalinko, A.; Kubicki, J.; Kertmen, A.; Lindner, N.; Khakhulin, D.; Lima, F. A.; Choi, T.-K.; Biednov, M.; Schmitz, L.; Piergies, N.; Zalden, P.; Kubicek, K.; Rodriguez-Fernandez, A.; Salem, M. A.; Canton, S. E.; Bressler, C.; Kühne, T. D.-S.; Gawelda, W.; Bauer, M.

Abstract

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light-induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X-ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time-dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X-ray emission at the iron and cobalt K-edges in a two-color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled.

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Permalink: https://www.hzdr.de/publications/Publ-40262


Low energy positron beams

Wagner, A.

Abstract

Low-energy positron beams II, new developments by Andreas Wagner

  • Accelerator-based sources
o Technologies (RI-production online 12C(d,n)13N (Weber&Lynn), 65Cu(g,n)64Cu
o LINAC bremsstrahlung and pulsed beams (AIST, KEK, HZDR, CERN), GiPS-like (INL, HZDR)
o Polarized beams (Beppo, QST/RIKEN )
  • Beam transport and beam optics, numerical (G4Beamline)

Keywords: positron annihilation lifetime spectroscopy; bremstrahlung; materials science

Involved research facilities

Related publications

  • Lecture (others)
    Summerschool Alfredo Dupasquier on Positron Annihilation, 31.08.-01.09.2024, Como, Italia

Permalink: https://www.hzdr.de/publications/Publ-40261


Isostructural Series of a Cyclometalated Iron Complex in Three Oxidation States

Steube, J.; Fritsch, L.; Kruse, A.; Bokareva, O. S.; Demeshko, S.; Elgabarty, H.; Schoch, R.; Alaraby, M.; Egold, H.; Bracht, B.; Schmitz, L.; Hohloch, S.; Kühne, T. D.-S.; Meyer, F.; Kühn, O.; Lochbrunner, S.; Bauer, M.

Abstract

An isostructural series of FeII, FeIII, and FeIV complexes [Fe(ImP)2]0/+/2+ utilizing the ImP 1,1′-(1,3-phenylene)bis(3-methyl-1-imidazol-2-ylidene) ligand, combining N-heterocyclic carbenes and cyclometalating functions, is presented. The strong donor motif stabilizes the high-valent FeIV oxidation state yet keeps the FeII oxidation state accessible from the parent FeIII compound. Chemical oxidation of [Fe(ImP)2]+ yields stable [FeIV(ImP)2]2+. In contrast, [FeII(ImP)2]0, obtained by reduction, is highly sensitive toward oxygen. Exhaustive ground state characterization by single-crystal X-ray diffraction, 1H NMR, Mössbauer spectroscopy, temperature-dependent magnetic measurements, a combination of X-ray absorption near edge structure and valence-to-core, as well as core-to-core X-ray emission spectroscopy, complemented by detailed density functional theory (DFT) analysis, reveals that the three complexes [Fe(ImP)2]0/+/2+ can be unequivocally attributed to low-spin d6, d5, and d4 complexes. The excited state landscape of the FeII and FeIV complexes is characterized by short-lived 3MLCT and 3LMCT states, with lifetimes of 5.1 and 1.4 ps, respectively. In the FeII-compound, an energetically low-lying MC state leads to fast deactivation of the MLCT state. The distorted square-pyramidal state, where one carbene is dissociated, can not only relax into the ground state, but also into a singlet dissociated state. Its formation was investigated with time-dependent optical spectroscopy, while insights into its structure were gained by NMR spectroscopy.

Permalink: https://www.hzdr.de/publications/Publ-40260


Understanding the Wettability of C1N1 (Sub)Nanopores: Implications for Porous Carbonaceous Electrodes

Lamata-Bermej, I.; Keil, W.; Nolkemper, K.; Heske, J.; Kossmann, J.; Elgabarty, H.; Wortmann, M.; Chorążewski, M.; Schmidt, C.; Kühne, T. D.-S.; López-Salas, N.; Odziomek, M.

Abstract

Understanding how water interacts with nanopores of carbonaceous electrodes is crucial for energy storage and conversion applications. A high surface area of carbonaceous materials does not necessarily need to translate to a high electrolyte-solid interface area. Herein, we study the interaction of water with nanoporous C1N1 materials to explain their very low specific capacitance in aqueous electrolytes despite their high surface area. Water was used to probe chemical environments, provided by pores of different sizes, in 1H MAS NMR experiments. We observe that regardless of their high hydrophilicity, only a negligible portion of water can enter the nanopores of C1N1, in contrast to a reference pure carbon material with a similar pore structure. The common paradigm that water easily enters hydrophilic pores does not apply to C1N1 nanopores below a few nanometers. Calorimetric and sorption experiments demonstrated strong water adsorption on the C1N1 surface, which restricts water mobility across the interface and impedes its penetration into the nanopores.

Permalink: https://www.hzdr.de/publications/Publ-40259


Nicht nur effizient, sondern auch verantwortungsvoll - VECTOR-Projekt erforscht ganzheitliche Konzepte für die Rohstoffgewinnung in der EU

Pereira, T.

Abstract

Bergbau ist kontrovers. Einerseits braucht unsere moderne Gesellschaft Rohstoffe wie Lithium für die Transformation hin zu klimafreundlichen Technologien. Andererseits werden Erkundung und Rohstoffabbau vor allem mit Umweltverschmutzung und Ausbeutung in Verbindung gebracht. In Europa ist diese Kontroverse aktueller denn je. Die EU möchte erreichen, dass Unternehmen wieder mehr Rohstoffe aus heimischen Lagerstätten gewinnen, um die Rohstoffabhängigkeit von Drittstaaten zu minimieren, so wie im Critical Raw Materials Act beschrieben. Gleichzeitig stehen Rohstoffprojekte vor komplexen technischen und sozialen Herausforderungen, wie z. B. dem Aufsuchen von Vorkommen in großen Tiefen oder gesellschaftlichen Vorbehalten gegenüber Erkundungsarbeiten. Genau in diesem Spannungsfeld forscht seit zwei Jahren das HORIZON EUROPE-Projekt VECTOR. Spezialisten aus den Bereichen Geo-, Sozial- und den Datenwissenschaften erarbeiten gemeinsam neue, auf den Menschen ausgerichtete Lösungsansätze, die eine effiziente und sozialverträgliche Versorgung von insbesondere kritischen Rohstoffen in Europa ermöglichen soll.

Keywords: minimal-invasive Erkundung; Sozialwissenschaften; Metallische Rohstoffe; VECTOR-Projekt; Shared Value

  • Open Access Logo Acamonta 31(2024), 36-40
    ISSN: 2193-309X

Permalink: https://www.hzdr.de/publications/Publ-40258


Advances of the Helmholtz Institute Freiberg for Resource Technology in Geometallurgy

Pereira, L.; Tolosana Delgado, R.; Frenzel, M.; Rudolph, M.; van den Boogaart, K. G.; Gutzmer, J.

Abstract

In this presentation, a series of case studies developed at the Helmholtz Institute Freiberg for Resource Technology related to geometallurgy are presented.

Keywords: geometallurgy; particle-based separation models

  • Invited lecture (Conferences)
    Scientific seminar of the geosciences team @ BHP, 20.08.2024, Perth, Australia

Permalink: https://www.hzdr.de/publications/Publ-40257


High intensity positron beams from an SC-LINAC for materials research

Wagner, A.

Abstract

Presentation of the positron beamlines at the superconducting LINAC ELBE which are being used for positron annihilation lifetime spectroscopy.

Keywords: positron annihilation lifetime spectroscopy; materials research; superconducitng LINAC

Involved research facilities

Related publications

  • Invited lecture (Conferences) (Online presentation)
    Advances in High-Intensity Positron Source Physics and Technologies (AHIPS-2024), 16.-18.10.2024, Orsay, France
  • Lecture (others)
    Institutsseminar, 21.11.2024, Bratislava, Slovenska

Permalink: https://www.hzdr.de/publications/Publ-40256


Analytical Solutions of Symmetric Isotropic Spin Clusters Using Spin and Point Group Projectors

Ghassemi Tabrizi, S.; Kühne, T. D.-S.

Abstract

Spin models like the Heisenberg Hamiltonian effectively describe the interactions of open-shell transition-metal ions on a lattice and can account for various properties of magnetic solids and molecules. Numerical methods are usually required to find exact or approximate eigenstates, but for small clusters with spatial symmetry, analytical solutions exist, and a few Heisenberg systems have been solved in closed form. This paper presents a simple, generally applicable approach to analytically solve isotropic spin clusters, based on adapting the basis to both total spin and point group symmetry to factor the Hamiltonian matrix into sufficiently small blocks. We demonstrate applications to small rings and polyhedra, some of which are straightforward to solve by successive spin-coupling for Heisenberg terms only; additional interactions, such as biquadratic exchange or multi-center terms necessitate symmetry adaptation.

Permalink: https://www.hzdr.de/publications/Publ-40255


Particle-based separation models: a tool to better understand separation processes and to enable predictive geometallurgy

Pereira, L.; Tolosana Delgado, R.; Frenzel, M.; Rudolph, M.; van den Boogaart, K. G.; Gutzmer, J.

Abstract

Have you ever wondered: what degree of liberation is needed for my ore to float? Or what is the optimum grinding size for the recovery of my ore? In this lecture, you will learn how automated mineralogy data, which is typically only partially used, can be applied to understand the behaviour of each particle in mineral processing. Besides, we will cover how these models can be used to forecast the recoverability of entire orebodies

Keywords: Particle-based separation modelling; geometallurgy; geostatistics

  • Lecture (others) (Online presentation)
    Geometallurgy scientific discussions @ Teck, 21.11.2024, Vancouver, Canada

Permalink: https://www.hzdr.de/publications/Publ-40254


Photocatalytic CO2 reduction to syngas using nickel phosphide-loaded CdS under visible light irradiation

Yadav, P.; Kumar, S.; Velankanni, N.; Kühne, T. D.-S.; Gosavi, S.; Kormath Madam Raghupathy, R.; Bhosale, R.; Held, G.; Shelke, M.; Ogale, S.

Abstract

Photocatalytic CO2 reduction is a sustainable pathway to produce syngas (H2 + CO), which is a key feedstock for the production of several important liquid fuels on the industrial scale. However, achieving an appropriate tunable ratio of H2:CO in syngas for commercial purposes is a challenging task. In this work, we present a low-cost and non-noble metal, phosphide-based co-catalyst—Ni2P-loaded cadmium sulfide (CdS) photocatalyst system, for photocatalytic CO2 reduction. As a co-catalyst, Ni2P fosters an efficient charge separation of photoexcited charges generated in the CdS production of syngas. In total, 3 wt.% Ni2P/CdS exhibited exceptional performance of 50.6 µmol g−1 h−1 in the CO evolution rate and 115 µmol g−1 h−1 in the H2 evolution rate, with a syngas composition varying from 2 to 4 in the H2:CO ratio. Furthermore, first-principles density functional theory calculations were performed to study the surface energetics of the catalyst system and the results are found to be consistent with our experimental findings. Indeed, they establish that the composite favors CO2 photoreduction into syngas more efficiently than pure surfaces.

Permalink: https://www.hzdr.de/publications/Publ-40253


Uso da Mineralogia Automatizada na Geometalurgia Preditiva

Pereira, L.

Abstract

Você já se perguntou: qual o grau de liberação necessário para meu minério flotar? Ou qual o tamanho ótimo de moagem para a recuperação do meu minério? Neste minicurso você aprenderá como dados de mineralogia automatizada, que tipicamente são apenas parcialmente usados, podem ser aplicados para compreender o comportamento de cada partícula no processamento mineral.

Keywords: geometallurgy; particle-based separation models

  • Invited lecture (Conferences)
    I Simpósio de Geometalurgia, 24.-25.06.2024, Belo Horizonte, Brazil

Permalink: https://www.hzdr.de/publications/Publ-40252


Nuclear quantum effects on the vibrational dynamics of the water–air interface featured

Ojha, D.; Henao, A.; Zysk, F.; Kühne, T. D.-S.

Abstract

We have applied path-integral molecular dynamics simulations to investigate the impact of nuclear quantum effects on the vibrational dynamics of water molecules at the water–air interface. The instantaneous fluctuations in the frequencies of the O–H stretch modes are calculated using the wavelet method of time series analysis, while the time scales of vibrational spectral diffusion are determined from frequency-time correlation functions and joint probability distributions. We find that the inclusion of nuclear quantum effects leads not only to a redshift in the vibrational frequency distribution by about 120 cm−1 for both the bulk and interfacial water molecules but also to an acceleration of the vibrational dynamics at the water–air interface by as much as 35\%. In addition, a blueshift of about 45 cm−1 is seen in the vibrational frequency distribution of interfacial water molecules compared to that of the bulk. Furthermore, the dynamics of water molecules beyond the topmost molecular layer was found to be rather similar to that of bulk water.

Permalink: https://www.hzdr.de/publications/Publ-40250


Forecasting the recovery potential of a tailings storage facility with particle-based separation models

Pereira, L.; Ghebreyesus, S.; Frenzel, M.; Hoang, D. H.; Rudolph, M.; van den Boogaart, K. G.; Gutzmer, J.; Tolosana Delgado, R.

Abstract

The reprocessing of tailings storage facilities (TSFs) is highly relevant given the potential to increase metal production and reduce environmental issues. Yet, in these TSFs, minerals are often contained within fine and non-liberated particles, which not only pose a challenge to their efficient concentration but also to forecasting the outcome of such activities. In this case, particle-based separation models, which account for particle complexity in their recovery estimation, are fundamental. This study covers the construction of a recovery model for a TSF from Germany, in which five flotation tests are required to reach a high accuracy in recovery predictions. Differences in flotation behavior in the different areas of the TSF seem to be hindering the quality of grade predictions.

Keywords: Tailings storage facility; geometallurgy; orebody modelling; particle-based separation models; geostatistics

  • Lecture (Conference)
    XXXI IMPC-International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, United States of America
  • Contribution to proceedings
    XXXI IMPC-International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, United States of America
    XXXI IMPC-International Mineral Processing Congress, Washington DC: Society for Mining, Metallurgy & Exploration (SME), 978-0-87335-518-6

Permalink: https://www.hzdr.de/publications/Publ-40248


Forecasting graphite recovery from spent lithium-ion batteries’ black mass with particle-based separation models

Pereira, L.; Guimaraes da Silva Tochtrop, C.; José Rodríguez Medina, A.; Bachmann, K.; Rudolph, M.; Vanderbruggen, A.

Abstract

The current increase in production of lithium-ion batteries claims for the development of technologies for their later recycling. Flotation has been successfully used for recovering spherodized graphite from the black mass of spent batteries. Forecasting flotation outcome from such a complex particle system remains a challenge. Automated mineralogy has been used for characterizing battery recycling materials, but the obtained data has so far only been partially used. Here, automated mineralogy and particle-based separation models are used to compute the recovery of individual particles from a model black mass at flotation tests done with different pulp solids content. Results indicate a 25 % higher flotation rate constant for graphite particles at lower solids content irrespective of particle size. Besides, evidence is presented for a distinct flotation mechanism of LiCoO2 and LiNiMnCoO2 in comparison to metal foils and an SiO2 entrainment tracer added to the system.

Keywords: Black mass; Lithium ion batteries; particle-based separation models; recycling

  • Lecture (Conference)
    XXXI IMPC-International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, United States of America
  • Contribution to proceedings
    XXXI IMPC-International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, United States of America
    XXXI IMPC-International Mineral Processing Congress, Washington DC: Society for Mining, Metallurgy & Exploration (SME), 978-0-87335-518-6

Permalink: https://www.hzdr.de/publications/Publ-40247


Assessing the selectivity of lithium aluminate recovery in flotation against several gangue phases from a slag system under different reagent systems

Strube, F.; Pereira, L.; Guy, B. M.; Rudolph, M.

Abstract

The extraction of metals from materials typically handled as waste, such as metallurgical slags, is key to maximizing the efficiency of raw materials within the value chain. Given the complexity of such materials, where phases are commonly intergrown and exceptionally fine-grained, achieving a high degree of process selectivity is challenging. In the case of Li-bearing slags, analytical limitations also hinder the assessment of process selectivity.
Based on the compositional and microstructural attributes of individual particles, particle-based separation models can quantify the recoverability of target phases within individual particles. These attributes, which include size, shape, liberation, and association, are routinely collected from automated scanning electron microscopes, and fed into the separation models to quantify the flotation performance of a complex Li-bearing slag system. In this study, three sets of reagent regimes are tested and process selectivity is assessed with considerations given to both chemical (process conditions) and physical (slag microstrucutures) challenges.

Keywords: Particle-based separation modelling; Lithium; Engineered artificial minerals; Slags

  • Lecture (Conference)
    Critical Minerals '24, 14.-15.11.2024, Cape Town, South Africa
  • Contribution to proceedings
    Critical Minerals '24, 14.-15.11.2024, Cape Town, South Africa
    Critical Minerals '24

Permalink: https://www.hzdr.de/publications/Publ-40246


Recovery of strategically important critical minerals: A Central African copper ore case study using novel co-collectors

Shackleton, N. J.; Malysiak, V.; Pereira, L.; Guy, B. M.; Mosai, G. S.

Abstract

Copper has been highlighted as a critical mineral to mitigate climate change and provide cleanenergy economy, however, major deficits are forecasted and therefore copper demand is expected to rise. This situation will become more severe if copper’s production continues at its current rate and given the declining copper head grades as well as the long time span needed for exploration of new sites, it has become necessary to improve existing processes.
This paper focuses on copper’s flotation performance using novel co-collectors developed for improved extraction of various copper-bearing minerals and thus creating added value for concentrators treating base metal sulphide (BMS) ores. The case study was conducted on a Central African ore, where batch
flotation tests were performed and the concentrates were characterised with automated mineralogy. Results show a strong correlation between the recovery of the different copper minerals and AECI Mining Chemicals novel co-collector type thereby improving copper recovery even at a lower overall reagent consumption

Keywords: Batch flotation; Mineralogy; Co-collectors; Cu minerals

  • Lecture (Conference)
    Critical Minerals '24, 14.-15.11.2024, Cape Town, South Africa
  • Contribution to proceedings
    Critical Minerals '24, 14.-15.11.2024, Cape Town, South Africa
    Critical Minerals '24

Permalink: https://www.hzdr.de/publications/Publ-40245


PECVD and PEALD on polymer substrates (part II): Understanding and tuning of barrier and membrane properties of thin films

de los Arcos, T.; Awakowicz, P.; Böke, M.; Boysen, N.; Brinkmann, R. P.; Dahlmann, R.; Devi, A.; Eremin, D.; Franke, J.; Gergs, T.; Jenderny, J.; Kemaneci, E.; Kühne, T. D.-S.; Kusmierz, S.; Mussenbrock, T.; Rubner, J.; Trieschmann, J.; Wessling, M.; Xie, X.; Zanders, D.; Zysk, F.; Grundmeier, G.

Abstract

This feature article presents insights concerning the correlation of plasma-enhanced chemical vapor deposition and plasma-enhanced atomic layer deposition thin film structures with their barrier or membrane properties. While in principle similar precursor gases and processes can be applied, the adjustment of deposition parameters for different polymer substrates can lead to either an effective diffusion barrier or selective permeabilities. In both cases, the understanding of the film growth and the analysis of the pore size distribution and the pore surface chemistry is of utmost importance for the understanding of the related transport properties of small molecules. In this regard, the article presents both concepts of thin film engineering and analytical as well as theoretical approaches leading to a comprehensive description of the state of the art in this field. Perspectives of future relevant research in this area, exploiting the presented correlation of film structure and molecular transport properties, are presented.

Permalink: https://www.hzdr.de/publications/Publ-40244


PECVD and PEALD on polymer substrates (part I): Fundamentals and analysis of plasma activation and thin film growth

de los Arcos, T.; Awakowicz, P.; Benedikt, J.; Biskup, B.; Böke, M.; Boysen, N.; Buschhaus, R.; Dahlmann, R.; Devi, A.; Gergs, T.; Jenderny, J.; von Keudell, A.; Kühne, T. D.-S.; Kusmierz, S.; Müller, H.; Mussenbrock, T.; Trieschmann, J.; Zanders, D.; Zysk, F.; Grundmeier, G.

Abstract

Abstract This feature article presents recent results on the analysis of plasma/polymer interactions and the nucleation of ultra-thin plasma films on polymeric substrates. Because of their high importance for the understanding of such processes, in situ analytical approaches of the plasma volume as well as the plasma/substrate interfaces are introduced before the findings on plasma surface chemistry. The plasma activation of polymeric substrates is divided into the understanding of fundamental processes on model substrates and the relevance of polymer surface complexity. Concerning thin film nucleation and growth, both plasma-enhanced chemical vapor deposition and plasma-enhanced atomic layer deposition processes as well as the combination of both processes are considered both for model substrates and technical polymers. Based on the comprehensive presentation of recent results, selective perspectives of this research field are discussed.

Permalink: https://www.hzdr.de/publications/Publ-40243


Data publication: Self-induced Floquet magnons in magnetic vortices

Heins, C.; Körber, L.; Kim, J.-V.; Devolder, T.; Mentink, J. H.; Kakay, A.; Faßbender, J.; Schultheiß, K.; Schultheiß, H.

Abstract

This data publication contains the data for our publication "Self-induced Floquet magnons in magnetic vortices". The dataset is structured in folders corresponding to the different figures in the paper. Folder Fig-2 contains the simulated spectra and the experimental spectra measured with Brillouin-light-scattering microscopy. The experimental spectra contain the data integrated for the measurement positions described in the methods section. Folder Fig-4 contains the evaluated numerical data presented in the corresponding panels. The raw data generated with micromagnetic simulations is too large for this dataset and is available upon request by the authors. Folder Fig-5 contains the experimental spectra measured with Brillouin-light-scattering microscopy as a function of power and time. Folder FIG-S1 contains the log file for the sample fabrication and scanning electron microscope (SEM) images. Important note for the SEM images: When acquiring the SEM images, the calibration of the Raith150 tool was off momentarily. This resulted in recording wrong scale bars with the images. The structure dimensions are known from the design file and were confirmed at another time after adjusting the calibration.

Keywords: magnetic vortex; magnon; Floquet states; nonlinearity

Involved research facilities

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-40242


Understanding Hydration in CPO-27 Metal-Organic Frameworks: Strong Impact of the Chemical Nature of the Metal (Cu, Zn)

Kloß, M.; Beerbaum, M.; Baier, D.; Weinberger, C.; Zysk, F.; Elgabarty, H.; Kühne, T. D.-S.; Tiemann, M.

Abstract

CPO-27 is a metal-organic framework (MOF) with coordinatively unsaturated metal centers (open metal sites). It is therefore an ideal host material for small guest molecules, including water. This opens up numerous possible applications, such as proton conduction, humidity sensing, water harvesting, or adsorption-driven heat pumps. For all of these applications, profound knowledge of the adsorption and desorption of water in the micropores is mandatory. The hydration and water structure in CPO-27-M (M = Zn or Cu) is investigated using water vapor sorption, Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT) calculations, and molecular dynamics simulation. In the pores of CPO-27-Zn, water binds as a ligand to the Zn center. Additional water molecules are stepwise incorporated at defined positions, forming a network of H-bonds with the framework and with each other. In CPO-27-Cu, hydration proceeds by an entirely different mechanism. Here, water does not coordinate to the metal center, but only forms H-bonds with the framework; pore filling occurs mostly in a single step, with the open metal site remaining unoccupied. Water in the pores forms clusters with extensive intra-cluster H-bonding.

Permalink: https://www.hzdr.de/publications/Publ-40241


Simulations of disordered matter in 3D with the morphological autoregressive protocol (MAP) and convolutional neural networks

Madanchi, A.; Kilgour, M.; Zysk, F.; Kühne, T. D.-S.; Simine, L.

Abstract

Disordered molecular systems, such as amorphous catalysts, organic thin films, electrolyte solutions, and water, are at the cutting edge of computational exploration at present. Traditional simulations of such systems at length scales relevant to experiments in practice require a compromise between model accuracy and quality of sampling. To address this problem, we have developed an approach based on generative machine learning called the Morphological Autoregressive Protocol (MAP), which provides computational access to mesoscale disordered molecular configurations at linear cost at generation for materials in which structural correlations decay sufficiently rapidly. The algorithm is implemented using an augmented PixelCNN deep learning architecture that, as we previously demonstrated, produces excellent results in 2 dimensions (2D) for mono-elemental molecular systems. Here, we extend our implementation to multi-elemental 3D and demonstrate performance using water as our test system in two scenarios: (1) liquid water and (2) samples conditioned on the presence of pre-selected motifs. We trained the model on small-scale samples of liquid water produced using path-integral molecular dynamics simulations, including nuclear quantum effects under ambient conditions. MAP-generated water configurations are shown to accurately reproduce the properties of the training set and to produce stable trajectories when used as initial conditions in quantum dynamics simulations. We expect our approach to perform equally well on other disordered molecular systems in which structural correlations decay sufficiently fast while offering unique advantages in situations when the disorder is quenched rather than equilibrated.

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Permalink: https://www.hzdr.de/publications/Publ-40240


Beyond metals: theoretical discovery of semiconducting MAX phases and their potential application in thermoelectrics

Khazaei, M.; Maleki, I.; Koshi, N. A.; Ranjbar, A.; Miao, N.; Wang, J.; Khaledialidusti, R.; Kühne, T. D.-S.; Lee, S.-C.; Bhattacharjee, S.; Hosano, H.; Mehdi Vaez Allaei, S.; Esfarjani, K.; Ohno, K.

Abstract

MAX phase is a family of ceramic compounds, typically known for their metallic properties. However, we show here that some of them may be narrow bandgap semiconductors. Using a series of first-principles calculations, we have investigated the electronic structures of 861 dynamically stable MAX phases. Notably, Sc2SC, Y2SC, Y2SeC, Sc3AuC2, and Y3AuC2 have been identified as semiconductors with band gaps ranging from 0.2 to 0.5 eV. Furthermore, we have assessed the thermodynamic stability of these systems by generating ternary phase diagrams utilizing evolutionary algorithm techniques. Their dynamic stabilities are confirmed by phonon calculations. Additionally, we have explored the potential thermoelectric efficiencies of these materials by combining Boltzmann transport theory with first-principles calculations. The relaxation times are estimated using scattering theory. The zT coefficients for the aforementioned systems fall within the range of 0.5 to 2.5 at temperatures spanning from 300 to 700 K, indicating their suitability for high-temperature thermoelectric applications.

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Permalink: https://www.hzdr.de/publications/Publ-40239


Remarkable Optoelectronic Characteristics of Synthesizable Square-Octagon Haeckelite Structures: Machine Learning Materials Discovery

Alibagheri, E.; Ranjbar, A.; Khazaei, M.; Kühne, T. D.-S.; Vaez Allaei, S. M.

Abstract

The research explores new compounds with structures similar to square-octagonal beryllium oxide, commonly known as Haeckelites. The goal is to identify semiconducting variations compounds that can be synthesized and show promising potential in optoelectronic devices. Start with 1083 binary Haeckelite structures, and to test the synthesis potential of these materials quickly, develop new descriptors and use machine learning techniques. As a result, it identifies a subset of 350 materials with suitable properties in terms of phase stability and electronic perspective. These materials are further investigated to analyze their electronic structure and phase stability, which are determined through density functional theory calculations. The phase stabilities of the predicted semiconducting Haeckelites are also compared to other binary compounds using an evolutionary structure search algorithm. The comprehensive methodology also includes examining the dynamic stabilities through phonon calculations and mechanical properties through elastic constant calculations. Eventually, 13 new Haeckelite compounds are discovered, demonstrating exceptional stability and performance in electronic tests. Among these compounds, eight have shown remarkable absorption coefficients and are considered promising candidates with high reflectivity. Additionally, they have exhibited high electron mobility. These findings strongly suggest the potential of these compounds for synthesis and their application in optoelectronic devices.

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Permalink: https://www.hzdr.de/publications/Publ-40238


Ab Initio Molecular Dynamics: A Guide to Applications

Hutter, J.; Iannuzzi, M.; Kühne, T. D.-S.

Abstract

Ab initio molecular dynamics (AIMD) is an important simulation method applied to understand systems encountered in chemistry and biochemistry, as well as in physics and materials science. It provides means to study complex systems undergoing chemical reactions or phase transitions, as occurring in systems under extreme conditions, or previously unknown compositions. We introduce the basic concepts and methods of AIMD when used together with density functional theory approaches. The connection between the currently most widely used methods, Born–Oppenheimer MD and 2 n d Generation Car–Parrinello MD is derived. Important parameters for efficient and accurate simulation protocols are discussed with the focus on the implementations in the CP2K software. Step by step procedures to correctly set up simulations are provided. Sample applications from literature are presented with a special emphasis on the simulation system parameters and protocols used.

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Permalink: https://www.hzdr.de/publications/Publ-40237


Using the ODD protocol and NetLogo to replicate agent-based models

Grimm, V.; Berger, U.; Calabrese, J.; Cortés-Avizanda, A.; Ferrer, J.; Franz, M.; Groeneveld, J.; Hartig, F.; Jakoby, O.; Jovani, R.; Kramer-Schadt, S.; Münkemüller, T.; Piou, C.; Premo, L.; Pütz, S.; Quintaine, T.; Rademacher, C.; Rüger, N.; Schmolke, A.; Thiele, J.; Touza, J.; Railsback, S.

Abstract

Replicating existing models and their key results not only adds credibility to the original work, it also allows modellers to start model development from an existing approach rather than from scratch. New theory can then be developed by changing the assumptions or scenarios tested, or by carrying out more in-depth analysis of the model. However, model replication can be challenging if the original model description is incomplete or ambiguous. Here we show that the use of standards can facilitate and speed up replication: the ODD protocol for describing models, and NetLogo, an easy-to-learn but powerful software platform and language for implementing agent-based models. To demonstrate the benefits of this approach, we conducted a replication experiment on 18 agent-based models from different disciplines. The researchers doing the replications had no or little previous experience using ODD and NetLogo. Their task was to rewrite the original model description using ODD, implement the model in NetLogo and try to replicate at least one exemplary main result. They were also asked to produce, if time allowed, some initial new results with the replicated model, and to record the total time spent on the replication exercise. Replication was successful for 15 out of 18 models. The time taken varied between 2 and 12 days, with an average of 5 days. ODD helped to systematically scan the original model description, while NetLogo proved easy and quick to learn, but difficult to debug when implementation problems arose. Although most of the models replicated were relatively simple, we conclude that even for more complex models it can be useful to use ODD and NetLogo for replication, at least for developing a prototype to help decide how to proceed with the replicated model. Overall, the use of both, standard approaches such as ODD and easy to learn but powerful software such as NetLogo, can promote coherence and efficiency within and between different models and modelling communities. Imagine if all modellers spoke ODD and NetLogo as a common language or lingua franca.

Permalink: https://www.hzdr.de/publications/Publ-40235


Estimation of fracture propagation during impact testing using X-ray microtomography

Mora, D.; Lois-Morales, P.; Moraga, S.; da Assuncao Godinho, J. R.; Pereira, L.

Abstract

Fracture propagation in complex ore particles is still a largely unexplored subject. Understanding the link between particle properties and the breakage nature is critical for enabling selective breakage, a key development for enhancing the efficiency of raw material beneficiation plants. This study introduces a novel methodology to quantify the three-dimensional extension and propagation of fractures in particles of complex microstructure. Three particles (ranging from 2 to 5 mm) were analysed using X-ray computed tomography (XCT) before and after being subjected to impact using an impact load cell. The reconstructed particle tomograms were classified using deep-learning segmentation techniques.
The analysis of pre and post-impact XCT tomograms allowed quantification of the extension of fracture planes created within the particles. These fractures were examined as a function of associated minerals, pre-existing fractures and the mass-specific fracture energy absorbed by particles. It was concluded that fracture propagation is significantly impacted by the intergrowth of phases with different mechanical properties, such as calcite, albite and magnetite.

Keywords: X-Ray Computed Tomography; Comminution; Impact testing; Fracture propagation

  • Lecture (Conference)
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
  • Contribution to proceedings
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
    Process Mineralogy '24

Permalink: https://www.hzdr.de/publications/Publ-40234


Data publication: Nonreciprocal spin-wave dispersion in magnetic bilayers

Heins, C.; Iurchuk, V.; Gladii, O.; Körber, L.; Kakay, A.; Faßbender, J.; Schultheiß, K.; Schultheiß, H.

Abstract

The repository contains the experimental BLS data and script files to generate the simulated data with TetraX.

Related publications

  • ARXIV: 2412.09704 is supplemented by this (Id 40233) publication

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Permalink: https://www.hzdr.de/publications/Publ-40233


A geometallurgical approach to by-product recovery from rare-metal granites

Prado Araujo, F.; Vassilieva, E.; Dehaine, Q.; Lavikko, S.; Frenzel, M.; Guy, B. M.; Pereira, L.; Demeusy, B.; Filippov, L.; Muchez, P.

Abstract

Current mining practices generate substantial volumes of waste, including waste rock, tailings, and metallurgical residues. The storage of these side streams incurs high maintenance costs and social-environmental risks. Additionally, valuable by-products are often overlooked and disposed of with these wastes. To prevent by-products from being lost in tailings, we investigate a set of rare-metal granites to evaluate by-product recovery potential along the lithium beneficiation flowsheet. Adopting a geometallurgical approach is crucial for designing efficient recovery processes of critical raw materials (CRM: e.g., Li, Ta, Nb, Be, Sn) and industrial minerals, while also managing potentially harmful elements. Key findings include the presence of CRM-bearing minerals like lepidolite, cassiterite, columbite-tantalite, microlite, and Be-phosphates, alongside quartz and feldspars as industrial minerals. Analyses of mineralogical microstructural properties of the ores, coupled with elemental deportment studies, aid in designing downstream processes and assessing the suitability of by-product extraction routes for various applications. This integrated approach aims to minimize environmental impacts while increasing revenue opportunities.

Keywords: Li deposits; geometallurgy; critical raw materials; battery metals

  • Lecture (Conference)
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
  • Contribution to proceedings
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
    Process Mineralogy '24

Permalink: https://www.hzdr.de/publications/Publ-40232


Quantifying the flotation kinetics of various copper-bearing minerals from the Central African Copper Belt under unique reagent regimes with particle-based separation models

Pereira, L.; Guy, B. M.; Shackleton, N. J.; Malysiak, V.

Abstract

Much attention is given to increasing the efficiency of mining operations given the clear economic and strategic benefits. Guaranteeing the recovery of by- and co-products is an indispensable step to maximizing the raw materials efficiency of mining operations. This step requires a thorough understanding of the process behavior of target and gangue minerals in the ore, so that the processing route can be optimized.
Particle-based separation models, currently under extensive development, can quantify the recoverability of individual ore particles based on their different microstructural properties, such as size, shape, composition, liberation, and association. In this contribution, these models are used to quantify the flotation kinetics of particles containing several copper-bearing minerals from the Central African Copper Belt as a function of their microstructures. Five sets of reagent regimes are tested to evaluate their influence in each of these minerals. The recoverability of gangue minerals is also evaluated to better understand challenges in selectivity.

Keywords: Particle-based separation modelling; Chalcocite; Bornite; Collector mixtures; Central African Copper Belt

  • Lecture (Conference)
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
  • Contribution to proceedings
    Process Mineralogy '24, 10.-13.11.2024, Cape Town, South Africa
    Process Mineralogy '24

Permalink: https://www.hzdr.de/publications/Publ-40231


Data publication: Pair Production in Circularly Polarized Waves

Kohlfürst, C.

Abstract

Data sets used to generate the figures and tables in the associated paper. In addition, Matlab files have been attached to ensure that the data can be read correctly.

Keywords: Strong-Field Quantum Electrodynamics; Electron-Positron Pair Production; Breit-Wheeler Process; Non-equilibrium quantum field theory; Wigner formalism

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-40230


A novel, scenario-based approach to comparing non-pharmaceutical intervention strategies across nations

Calabrese, J.; Schüler, L.; Fu, X.; Gawel, E.; Zozmann, H.; Bumberger, J.; Quaas, M.; Wolf, G.; Attinger, S.

Abstract

Comparing COVID-19 response strategies across nations is a key step in preparing for future pandemics. Conventional comparisons, which rank individual non-pharmaceutical intervention (NPI) effects, are limited by: (i) a focus on epidemiological outcomes; (ii) NPIs typically being applied as packages of interventions; and (iii) different political, economic and social conditions among nations. Here, we develop a coupled epidemiological–behavioural–macroeconomic model that can transfer NPI effects from a reference nation to a focal nation. This approach quantifies epidemiological, behavioural and economic outcomes while accounting for both packaged NPIs and differing conditions among nations. As a first proof of concept, we take Germany as our focal nation during Spring 2020, and New Zealand and Switzerland as reference nations with contrasting NPI strategies. Our results suggest that, while New Zealand’s more aggressive strategy would have yielded modest epidemiological gains in Germany, it would have resulted in substantially higher economic costs while dramatically reducing social contacts. In contrast, Switzerland’s more lenient strategy would have prolonged the first wave in Germany, but would also have increased relative costs. More generally, these findings indicate that our approach can provide novel, multifaceted insights on the efficacy of pandemic response strategies, and therefore merits further exploration and development.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-40229


Home range spillover in habitats with impassable boundaries: Causes, biases, and corrections using autocorrelated kernel density estimation

Hollins, J.; Fleming, C.; Calabrese, J.; Harris, L.; Moore, J. S.; Malley, B.; Noonan, M.; Fagan, W.; Alston, J.; Hussey, N.

Abstract

An animal’s home range plays a fundamental role in determining its resource use and overlap with conspecifics, competitors and predators, and is therefore a common focus of movement ecology studies. Autocorrelated kernel density estimation addresses many of the shortcomings of traditional home range estimators when animal tracking data is autocorrelated, but other challenges in home range estimation remain. One such issue is known as ‘spillover bias’, in which home range estimates do not respect impassable movement boundaries (e.g., shorelines, fences), and occurs in all forms of kernel density estimation. While several approaches to addressing spillover bias are used when estimating home ranges, these approaches introduce bias throughout the remaining home range area, depending on the amount of spillover removed, or are otherwise inaccessible to most ecologists. Here, we introduce local corrections to home range kernels to mitigate spillover bias in (autocorrelated) kernel density estimation in the continuous time movement model (ctmm) package, and demonstrate their performance using simulations with known home range extents and distributions, and a real world case study. Simulation results showed that local corrections minimised bias in bounded home range area estimates, and resulted in more accurate distributions when compared to commonly used post-hoc corrections, particularly at small-intermediate sample sizes. Comparison of the impacts of local vs post-hoc corrections to bounded home ranges estimated from lake trout (Salvelinus namaycush) demonstrated that local corrections constrained bias within the remaining home range area, resulting in proportionally smaller home range areas compared to when post-hoc corrections are used.

Permalink: https://www.hzdr.de/publications/Publ-40226


Simultaneous identification of changepoints and model parameters in switching dynamical systems

Fu, X.; Fan, K.; Zozmann, H.; Schüler, L.; Calabrese, J.

Abstract

Many complex natural systems undergo shifts in dynamics at particular points in time. Examples include phase transitions in gene expression during the cell cycle, introduced species affecting predator-prey interactions, and disease outbreaks responding to intervention measures. Such changepoints partition timeseries into different dynamical regimes characterized by distinct parameter sets, and inference on both the changepoints and regime-specific dynamical parameters is of primary interest. Conventional approaches to analyzing switching dynamical systems first estimate changepoints, and then estimate dynamical parameters assuming the changepoints are fixed and known. Such two-stage approaches are ad-hoc, can introduce biases in the analysis, and do not fully account for uncertainty. Here, we introduce a rigorous, simulation-based inference framework that simultaneously estimates changepoints and model parameters from noisy data while admitting full uncertainty. We use simulation studies of oscillatory predator-prey dynamics and stochastic gene expression to demonstrate that our method yields accurate estimates of changepoints and model parameters together with appropriate uncertainty bounds. We then apply our approach to a real-world case study of COVID-19 intervention effects, and show that our inferred changepoints aligned closely with the actual dates of intervention implementation. Taken together, these results suggest that our framework will have broad utility in diverse scientific domains.

Permalink: https://www.hzdr.de/publications/Publ-40225


Investigating the influence of particle size and shape on froth flotation based beneficiation of lithium rich minerals in slags

Strube, F.; Wilhelm, T.; Sygusch, J.; Guy, B. M.; Furat, O.; Schmidt, V.; Rudolph, M.

Abstract

The demand for lithium, as well as other critical resources, needed for the energy transition is expected to grow significantly in the future. Slags obtained from pyrometallurgical recycling represent a promising resource of valuable materials, among them lithium and rare earth elements found in artificial mineral particulate phases. This study investigates the flotation separation of engineered artificial minerals (EnAM) in slags, such as lithium aluminate and gehlenite as valuable and gangue phases, respectively, with a focus on collector chemistry. Characterization is achieved via SEM-based Mineral Liberation Analysis (MLA), from which discrete particle information is obtained, thus enabling the investigation of multiple particle properties on the separation.

Keywords: Slag; engineered artificial mineral; multidimensional separation; froth flotation; MLA; multivariate

  • Open Access Logo Lecture (Conference)
    IMPC 2024 - International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, USA
    DOI: 10.48550/arXiv.2402.02818
  • Open Access Logo Contribution to proceedings
    International Mineral Processing Congress, 29.09.-03.10.2024, Washington DC, USA
    Proceedings of the International Mineral Processing Congress

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Permalink: https://www.hzdr.de/publications/Publ-40224


Interfacial properties of Li-bearing phases in slags supported by AFM for flotation separation purposes

Strube, F.; Rudolph, M.

Abstract

Due to the increased utilization of batteries e.g. in electric mobility, lithium has been classified as a critical raw material. Lithium can be enriched as engineered artificial minerals (EnAM) in slags from pyrometallurgical recycling of batteries, which can be controlled by the thermodynamic process conditions. It was found that cooling and additive regimes promote the enrichment of lithium in the key EnAMs phase lithium aluminate embedded in the gangue mineral gehlenite. The regimes also influence crystallite shapes, sizes and the formation of other Li-bearing EnAMs.
As a widely established heterocoagulation separation process for the raw materials industry, froth flotation is becoming increasingly important for upgrading and sorting those critical materials like EnAms. The key selection criterion is the difference in (de)wett(ing)ability of the surfaces of particulate phases. In order to circumvent the challenging conventional microflotation tests to quantitatively asses physicochemical surface properties of the Al2O3-CaO-Li2O-(MgO)-MnO-SiO2 slag system in combination with often complex reagent and collector systems, interaction scanning with atomic force microscopy (AFM) is used to study flotation parameters. For assessing different key surface properties, such as surface potentials and hydrophobization, which depend on the chosen reagent regime and strongly influence the interaction of the sample and the reagents, different hydrophilic and hydrophobic colloidal probe AFM measurements in dry and liquid mode are performed and discussed.
For this study, slag samples as well as the representative Lithium bearing model system with the valuable mineral Spodumene and the representative gangue phase Quartz were analyzed for their composition and material properties depending on temperature and additive regime. The AFM investigations are set in context with common micro flotation experiments and further characterization techniques. The potential of an Atomic Force Microscopy based approach to flotability assessment for unconventional resources, such as slags enriched with critical elements like lithium are demonstrated and discussed. This project is part of the priority program PP2315 on engineered artificial minerals and their processing, which is funded by the DFG (German Research Foundation).

Keywords: Recycling; Slag; Engineered Artificial Minerals; Atomic Force Microcopy; Flotation

  • Lecture (Conference)
    Jahrestreffen der DECHEMA/VDI-Fachgruppen Grenzflächenbestimmte Systeme und Prozesse, Kristallisation, Mechanische Flüssigkeitsabtrennung und Partikelmesstechnik, 27.-28.02.2024, Frankfurt am Main, Deutschland
  • Poster
    Jahrestreffen der DECHEMA/VDI-Fachgruppen Grenzflächenbestimmte Systeme und Prozesse, Kristallisation, Mechanische Flüssigkeitsabtrennung und Partikelmesstechnik, 27.-28.02.2024, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40223


Die Wiedergewinnung von Rohstoffen: Recycling und Kreislaufwirtschaft

Lederer, F.

Abstract

Vorstellung von aktuellen Recyclingwegen von Rohstoffen

Keywords: Kreislaufwirtschaft; Flexiplant; Biotechnologische Recyclingwege

  • Invited lecture (Conferences) (Online presentation)
    Säulen unserer Zivilisation – Zur Gewinnung und Wiederverwertung mineralischer Rohstoffe, 9.4.2024, Bochum, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40219


Biomoleküle – neue präzise Werkzeuge zum Recycling von Rohstoffen aus Abfallströmen

Lederer, F.

Abstract

Neue Wege zum biologischen Recycling von Rohstoffen wurden erörtert

Keywords: Peptide; Siderophore; Biotenside; Magnetseparation

  • Invited lecture (Conferences) (Online presentation)
    HAMBURG T.R.E.N.D. 2024, 17.-18.09.2024, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40218


BioKollekt – Neue biologische Trennverfahren für Seltene Erden aus Schrotten, Prozessabfällen und primären Rohstoffgemischen

Lederer, F.

Abstract

Vortrag über die BioKollekt Technologie zur Rückgewinnung seltener Erden

Keywords: Seltene Erden; Peptide; Kreislaufwirtschaft

  • Invited lecture (Conferences) (Online presentation)
    5. Sitzung des NA 066-03-11 AA "Seltene Erden", 28.11.2024, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40217


Biomolecular toolbox for resource recovery

Lederer, F.; Schönberger, N.; Techert, G.; Pollmann, K.

Abstract

Global challenges for the extraction of raw materials are constantly increasing. Decreasing metal contents of ore bodies and increasing ore complexities require more and more processing steps, which cause serious environmental problems. The demand for raw materials has increased worldwide due to new technologies, the growing complexity of the products composition as well as growing populations. However, at the end of a high-tech product’s lifetime, only the two to three most abundant elements are extracted while the majority of elements get lost. To strengthen a sustainable circular economy novel recycling strategies need to be developed that combine efficiently working traditional recycling steps with novel recycling steps to extract and reuse the majority of elements of our e-waste. Novel bio-based recycling tools are efficient and environmental friendly additions for the generation of a sustainable circular economy.
In our team, we develop such peptide-based recycling tools and processes. We apply phage surface display as a key technology for the identification of novel artificial peptides that selectively interact with minerals, metal ions and polymer surfaces [1]. These peptides are applied for the functionalization of magnetic particles to selectively separate target particles such as individual Rare Earth Elements that are part of fluorescent lamp powder and that are currently not recyclable. Filter-immobilized biomolecules are efficient and reusable tools for the recovery of ions such as Gallium from industrial wastewater [2]. The application of arsenic-binding peptides identified by our team [3] was just recently shown for the flotation of arsenic minerals [4].
In recent efforts, we seek to extend our discoveries and methods to an accessible knowledge platform. By providing best-practice recommendations for experimental approaches as well as bioinformatic tools for the identification of highly specific inorganic binding peptides as well as their technical utilization, we aim to provide an easily accessible biomolecular toolbox for resource recovery.
With our research, we want to prove that biological recycling strategies are combinable with efficiently working traditional recycling steps to increase the amount of extracted elements, decrease the environmental impact of toxic extraction agents as well as decrease the amount of waste.

Keywords: Peptides; Gallium; BioKollekt

  • Invited lecture (Conferences)
    Metal Binding Peptides Conference 2024, 09.-12.07.2024, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-40216


Active rheology control of responsive mortar with low slump value: Effect of magnetic field properties

Yiyuan, Z.; Yaxin, T.; Yi, Z.; da Assuncao Godinho, J. R.; Kim, V. T.; Karel, L.; Geert, D. S.

Abstract

To enhance the application of active rheology control, an experimental proof of concept for mortar with low
slump value was conducted. By adding magneto-responsive aggregates, a newly-developed 3D printable responsive
mortar was investigated. Six different magnetic intervention combinations were applied. The effect of magnetic
properties including magnetic flux density and magnetic induction line distribution on rheological behaviors
and microstructural properties of responsive mortar was focused upon. The magnetic field distribution was
simulated and visualized by COMSOL Multiphysics. Slow penetration tests and vane tests were performed to investigate
the structural build-up of responsive mortar. X-ray computed tomography (CT) was applied to determine
the spatial distribution of the pores and the magneto-responsive aggregates in responsive mortar. The orientation
of magneto-responsive clusters, total porosity, layer-by-layer porosity, and centers of gravity of magneto-
responsive aggregates were derived from the 3D images. The results indicate that magnetic field properties
had significant influence on the rheological response and microstructural properties. By designing a desirable
magnetic field, the buildability enhancement and/or reduction of a responsive mortar was achieved on demand,
in real time and in different directions.

Keywords: Responsive aggregates; Cement-based materials; Additive manufacturing; Magnetic field; X-ray computed tomography

Permalink: https://www.hzdr.de/publications/Publ-40215


Potentiale von Biomolekülen zur Trennung von Mikroschadstoffen und zur Rückgewinnung von Metallen aus Industriewasser

Lederer, F.

Abstract

Vorstellung der Methoden am HIF Biotech uzr Entfernung von Mikroschadstoffen aus Wasser

Keywords: Biotenside; Siderophore; Organische Säuren; Peptide

  • Lecture (others) (Online presentation)
    VLB Berlin, 21.05.2024, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40214


Biomolecular toolbox for resource recovery

Lederer, F.

Abstract

Application of biomolecules for resource recovery.

Keywords: Circular economy; metal resources; Biosurfactants; Siderophores; Peptides

  • Invited lecture (Conferences)
    BESSY III Workshop: Biocatalysis, 25.-26.04.2024, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40213


Layer interface characteristics and adhesion of 3D printed cement-based materials exposed to post-printing temperature disturbance

Yi, Z.; Yaxin, T.; da Assuncao Godinho, J. R.; Qiang, R.; Zhengwu, J.; Kim, V. T.; Geert, D. S.

Abstract

The layer interface, which is vital for the performance and longevity of 3D printed cement-based materials (3DPCM), is very sensitive to the environmental conditions because of the lack of formwork. Nevertheless, the current limited understanding of how temperature affects the layer interface has restricted the application of 3D printing in different construction scenarios. Here, we revealed the effects of temperature on the multi-scale phase distribution features of the layer interface through mercury intrusion porosimetry, X-ray computed tomography, nanoindentation and scanning electron microscopy with energy dispersive spectroscopy techniques. Additionally, the interlayer bond strength of 3DPCM was evaluated via the splitting tensile test. Small amplitude oscillation, surface roughness and isothermal calorimetry measurements were employed for an in-depth analysis of the mechanisms. Results indicate that an increase in temperature post-printing reduces the discrepancies in aggregate volume fraction between the layer interface and bulk matrix due to the increasing structuration rate and the amount of cement paste at the interface due to the reduced settlement of aggregates. The porosity difference between the layer interface and bulk matrix decreased with increasing temperature due to the pore size refinement by faster filling with hydrates. In addition, a more concentrated distribution of atomic ratios and elastic modulus of hydrates were observed at the layer interface of 3DPCM hardened at higher temperatures. Increased curing temperature improves the interlayer bond strength of 3DPCM owing to the enhanced aggregate interlocking, reduced porosity and improved high-density CSH content.

Keywords: Additive manufacturing; Temperature; Layer interface; Nanoindentation; Cement-based materials

Permalink: https://www.hzdr.de/publications/Publ-40212


Sustainable management of simulation setups for OpenFOAM Foundation Software

Lehnigk, R.; Schlegel, F.

Abstract

The software released by the OpenFOAM Foundation is developed with a strong focus on improving usability and maintainability. Functionality is kept as general as possible and as a result, the syntax for creating simulation setups evolves over time and it is not guaranteed that setups remain functional over a longer period of time without any adjustments. If users desire to keep their setups compatible, e.g., to repeatedly check validity for a certain application, they have to plan for maintenance work. The associated effort can be reduced if the setups are streamlined and placed under version control. In this demo we present a selection of tools that we found to be useful for developing and maintaining case setups. An approach for batch processing a larger set of simulation cases is demonstrated that can be used to conduct single timestep tests or full simulation runs in a scalable manner. The demo will highlight the benefits of using on a containerized installation of the OpenFOAM Foundation software. Furthermore, a solution for rendering simulations setups from templates is presented that allows to conduct efficient parameter studies.

Keywords: OpenFOAM; Computational Fluid Dynamics

  • Lecture (others) (Online presentation)
    Free VKI OpenFOAM Seminar, 14.10.2024, Sint-Genesius-Rode, Belgien
  • Lecture (Conference)
    20th Multiphase Flow Workshop - Short Course, 11.-13.11.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40210


Field-driven spin structure evolution in MnCr2S4: A high-field single-crystal neutron diffraction study

Duc, F.; Qureshi, N.; Suwa, H.; Ressouche, E.; Songvilay, M.; Prokhnenko, O.; Gazizulina, A.; Bourdarot, F.; Tsurkan, V.; Zherlitsyn, S.; Prodan, L.; Bertin, A.; Schneidewind, A.; Hoser, A.; Uhlarz, M.; Herrmannsdörfer, T.; Wosnitza, J.; Simonet, V.; Chattopadhyay, S.

Abstract

We present a comprehensive microscopic insight into the spin configurations within the bond-frustrated cubic spinel compound MnCr2S4 directly unveiled through extensive single-crystal neutron diffraction studies carried out in zero magnetic field and in fields up to 35 T. While our zero field results confirm the ferrimagnetic structure with an antiparallel arrangement of the magnetic Cr3+ and Mn2+ sublattices below TFiM ≈ 65 K, as well as the presence of the exotic Yafet-Kittel phase below TYK ≈ 5 K, our data measured in fields enable us to precisely determine the field-induced magnetic structures and their evolution across the phase transitions at μ0H1 ≈ 11 T and μ0H2 ≈ 25 T and beyond that towards μ0H3 (≈50 T). Additionally, combining our experimental findings with mean-field-theory calculations reveals a complex field dependence of the Mn-Mn and Mn-Cr exchange interactions across the different phases, highlighting the significant influence of spin-lattice coupling in this material.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-40207


Direct measurements of the conventional and rotational magnetocaloric effects in Gd thick films

Pereira, C. S.; Almeida, R.; Niehoff, T.; Kiefe, R.; Fontana, E.; Silva, D. J.; Gottschall, T.; Wosnitza, J.; Devillers, T.; Dempsey, N. M.; Amaral, J. S.; Belo, J. H.

Abstract

Magnetic refrigeration (MR) offers a sustainable and emission-free solution to the prevalent heat-pumping systems used worldwide. Typically, it utilizes the magnetocaloric effect (MCE) to achieve cooling by changing the external magnetic field intensity. However, an alternative approach involves maintaining a fixed field intensity while manipulating its orientation to induce temperature changes, in an effect known as the rotating MCE (RMCE). While the RMCE has been extensively studied in materials with magnetocrystalline anisotropy, its investigation in polycrystalline magnetocaloric samples with asymmetric shapes has been lacking until recently. In this case, the RMCE is induced by the demagnetizing effect, which becomes more pronounced in high aspect-ratio sample geometries exhibiting different effective demagnetizing factors at different orientations, such as in films. In this work, we characterize the conventional and rotational MCE of 40 μm-thick gadolinium films through magnetization and direct temperature measurements. The maximum adiabatic temperature change achieved under a 1 T magnetic field was 2.05 K when the film was oriented in plane with the field and 1.25 K when the film was perpendicular to the magnetic field, corresponding to an adiabatic temperature difference of around 0.8 K which may be induced through magnetic field rotation. Additionally, the maximum adiabatic temperature change upon rotation is shown to exhibit a non-monotonous behavior with field intensity, displaying a peak value for field intensities of around 0.8 T. The high aspect ratio of the Gd film has been demonstrated to considerably enhance the intensity of demagnetizing field-based RMCE compared to bulk samples, paving the way for future research in this emerging field of MR cooling.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-40206


Superconducting memory and trapped magnetic flux in ternary lanthanum polyhydrides

Semenok, D. V.; Sadakov, A. V.; Zhou, D.; Sobolevskiy, O. A.; Luther, S.; Helm, T.; Pudalov, V. M.; Troyan, I. A.; Struzhkin, V. V.

Abstract

Superconducting memory is a promising technology for data storage because of its speed, high energy efficiency, non-volatility, and compatibility with quantum computing devices. However, the need for cryogenic temperatures renders superconducting memory an extremely expensive and specialized device. Ternary lanthanum polyhydrides, due to their high critical temperatures of 240–250 K, represent a convenient platform for studying effects associated with superconductivity in disordered granular systems. In this work, we investigate trapped magnetic flux and memory effects in recently discovered lanthanum-neodymium (La,Nd)H10 and lanthanumscandium (La,Sc)H12 superhydrides at a pressure of 175–196 GPa. We use a steady magnetic field of a few Tesla (T) and strong pulsed fields up to 68 T to create the trapped flux state in the compressed superhydrides. We find a clockwise hysteresis of magnetoresistance in cerium CeH9-10 and lanthanum-cerium (La,Ce)H10+x polyhydrides, a characteristic feature of granular superconductors. A study of the current-voltage characteristics and voltage-temperature curves of the samples with trapped magnetic flux indicates a significant memory effect in La-Sc polyhydrides already at 225–230 K.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-40205


Continuum Excitations in a Spin Supersolid on a Triangular Lattice

Zhu, M.; Romerio, V.; Steiger, N.; Nabi, S. D.; Murai, N.; Ohira-Kawamura, S.; Povarov, K.; Scurschii, I.; Sibille, R.; Keller, L.; Yan, Z.; Gvasaliya, S.; Zheludev, A.

Abstract

Magnetic, thermodynamic, neutron diffraction and inelastic neutron scattering are used to study spin correlations in the easy-axis XXZ triangular lattice magnet K2Co(SeO3)2. Despite the presence of quasi-2D “supersolid” magnetic order, the low-energy excitation spectrum contains no sharp modes and is instead a broad and structured multiparticle continuum. Applying a weak magnetic field drives the system into an m = 1/3 fractional magnetization plateau phase and restores sharp spin wave modes. To some extent, the behavior at zero field can be understood in terms of spin wave decay. However, the presence of clear excitation minima at the M points of the Brillouin zone suggest that the spinon language may provide a more adequate description, and signals a possible proximity to a Dirac spin liquid state.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-40204


Differential Expression Analysis of Next-Generation Sequencing Data in Phage Display Trials

Bloß, C.; Harter, S. D.; Lederer, F.; Techert, G.

Abstract

Recycling rare earth elements from fluorescent powder of fluorescent light bulbs is at present not economically feasible. Peptide Identification using phage surface display (PSD) technology pushes recent efforts in biomolecular probes and materials science. However, the limitations of traditional phage display hamper the identification of the best binding peptides. Growth-induced library construction, off-target peptides and mutations often lead to the dominance of parasitic sequences and undocumented collapse of library diversity. Next generation sequencing (NGS) is a suitable complement to PSD as it provides deep insight into the sequence space of biopanning rounds, displays content, visualizes, and calculates phage library evolution during biopanning rounds. Yet, each sword has two edges- the number of counts usually varies greatly between individual biopanning rounds and available reads. Differential expression of peptides from phage display is one of the key challenges. The aim of this work is to find meaningful and statistically validated ways to identify metal-binding peptides in multiple-trail phage display experiments with inorganic materials. The thereby identified strong REE binding peptides can be used for novel bio-based recycling tools.

Keywords: materials identification and characterization of target; ngs data preparation methods joining; recycling of waste materials identification; Phage Display; Next-Generation Sequencing; Bioinformatics; Biotechnology; directed evolution method; characterization of target selective peptides ree

  • Lecture (Conference)
    11th International Work-Conference on Bioinformatics and Biomedical Engineering, 15.-17.07.2024, Gran Canaria, Spanien

Permalink: https://www.hzdr.de/publications/Publ-40203


EPICS device backend for the ChimeraTK framework

Zenker, K.

Abstract

The EPICS device backend implements a EPICS client, that allows to create an ChimeraTK device that communicates with an EPICS IOC via the EPICS Channel Access (CA) protocol.

Keywords: EPICS; ChimeraTK; Control System

Involved research facilities

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-40202


Numerical Investigation of Particle Mixing

Sanghvi, M. A.; Baecke, A. M.

Abstract

Industries perform mixing for fine-grained particles to form a new valuable product which would otherwise be discarded. The method of mixing is accompanied by segregation. This particle flow behaviour is predicted to gain better mixing efficiency. The study is focused on modelling the mixing process in a cylindrical bladed mixer. In this study, particles are considered as a continuum medium and modelled with ’OpenFOAM’ software.
Due to limited studies on particle mixing with the primary model, another model is incorporated called the rotating drum model to develop a validation benchmark, and later significant progress is achieved through the CBM model. An inbuilt solver of OpenFOAM known as ’interFoam’ is modified to perform particle mixing and segregation. It incorporates dynamic meshing to account for the rotor rotations in the mixer. Coupling is performed between the continuum equations and particle transport to account for particles as a continuum medium. It also integrates rheology models to capture intricate
effects of granular flow.
Firstly the cylindrical bladed mixer is modelled to perform mixing in 2D case and the corresponding mixing index plot is determined to understand the mixing efficiency. Later it is extended to a 3D model to perform mixing accompanied by segregation. The segregation mechanism is a function of particle size and density. The results obtained are validated with existing literature studies, with insights gained on the impact of operating parameters on the mixing efficiency. This study contributes to a novel approach to model particle segregation in mixers with a broader goal of improving the industrial mixing
process.

Keywords: Particles; Mixing; Segregation; Continuum model

  • Master thesis
    Brandenburgische Technische Universität Cottbus-Senftenberg (BTU), 2024
    Mentor: Anna Magdalena Baecke; Dr. Gregory Lecrivain
    98 Seiten

Permalink: https://www.hzdr.de/publications/Publ-40201


Influence of Large Magnetic Field Gradients at the Electrochemical Interface

Kurian, J.; Dunne, P.; Vivier, V.; Atcheson, G.; Salikhov, R.; Fowley, C.; Venkatesan, M.; Hellwig, O.; Coey, M.; Doudin, B.

Abstract

We investigate how a model single-electron-exchange electrochemical reaction can be influenced by a magnetic field, B, which is a combination of an external applied field and the stray field generated by a Co/Pt multilayer thin film stack with preferred perpendicular magnetization. The Lorentz force, proportional to B, creates gentle bath stirring. The magnetic field gradient force, proportional to grad B, is enhanced by the size reduction provided by nanoscale stripe domain patterns at the magnetic multilayer surface and acts locally at first tens of nm of the electrode/electrolyte interface. Cyclic voltammetry, chronoamperometry and impedance spectroscopy data reveals that such localized magnetic forces impact the electrochemical double layer, however with a change limited to around 7% when turning on and off the magnetic gradient force, with clear indications that the reaction kinetics remain unchanged. Our specific design of the magnetic field forces allows us to differentiate between these two main magnetic force effects and provides better insight into a controversial issue.

Keywords: Electrochemical interface; Magnetic thin films; Perpendicular magnetic anisotropy; Kelvin force; Magnetic field gradient force; Multi-domain film

  • Open Access Logo Book chapter
    B. Doudin, M. Coey, A. Cēbers: Magnetic Microhydrodynamics, Cham: Springer, 2024, 978-3-031-58376-6, 111-130
    DOI: 10.1007/978-3-031-58376-6_9

Permalink: https://www.hzdr.de/publications/Publ-40200


Challenges and solutions regarding TEM lamella preparation to investigate ion-beam-induced polymorph conversion in Ga2O3

Worbs, A.; Kunz, A.; Bektas, U.; Hlawacek, G.; Hübner, R.

Abstract

Gallium oxide (Ga2O3) is a promising ultra-wide bandgap semiconductor that has attracted much inter-est due to its easy large-scale production via melt growth and its high breakdown voltage. Among the various polymorphs, the main focus is on the beta phase, which is the most thermally and chemically stable polymorph of Ga2O3. Unfortunately, controlling and manufacturing other phases is immature due to the metastable structure of those phases and their conversion back to the beta phase at elevated temperatures.

Above a certain damage level, the polymorph conversion from the beta to the gamma phase is induced independently of the applied ion species [1]. The formed gamma phase is highly resistant against amor-phization. Based on implantation experiments with various ion species, strain induced by defects ra-ther than the chemical nature of the implanted ions seems to induce the phase transition.

To characterize the beta-to-gamma phase transition, investigate the interface between the non-trans-formed and transformed gallium oxide regions, and clarify the role of defects, the application of trans-mission electron microscopy imaging is indispensable. Since the Ga2O3 polymorph conversion is locally induced by various ion species, target preparation of the TEM specimens is needed. To this end, cross-sectional TEM lamellae were fabricated by in situ lift-out with a focused ion beam (FIB) system. Using conventional preparation strategies, strong bending of the TEM lamellae occurred, in particular during final thinning. To overcome these strain-related challenges, the geometry of the TEM lamella was ad-justed and the FIB parameters used during TEM specimen preparation were significantly modified. The presentation will show the various attempts to obtain non-bent specimens suitable for successful TEM analysis.

[1] A. Azarov, J. G. Fernandez, J. Zhao, F. Djurabekova, H. He, R. He, Ø. Prytz, L. Vines, U. Bektas, P. Chekhonin, N. Klingner, G. Hlawacek, A. Kuznetsov, Universal radiation tolerant semiconductor, Nature Communications 14 (2023) 4855.

Involved research facilities

Related publications

  • Poster
    FIT4NANO & EUFN Workshop, 16.-20.09.2024, Durres, Albanien

Permalink: https://www.hzdr.de/publications/Publ-40199


High-resolution UAV-based blueberry scorch virus mapping utilizing a deep vision transformer algorithm

Jamali, A.; Lu, B.; Gerbrandt, E. M.; Teasdale, C.; Burlakoti, R. R.; Sabaratnam, S.; McIntyre, J.; Yang, L.; Schmidt, M.; McCaffrey, D.; Ghamisi, P.

Abstract

Blueberry scorch virus (BIScV), transmitted by aphids, causes a serious disease in highbush blueberries with a significant economic impact. Early detection and mapping of the distribution of BIScV infected plants in fields are critical to implementing effective disease management practices, such as the timely removal of infected bushes and control of aphid vectors. The conventional visual plant assessment for symptoms remains dominant in BIScV detections, though it is labor-intensive, time-consuming, and costly. In recent years, the use of remote sensing techniques has become popular for in-field assessments of crop diseases and insect pests incidence, and thus provides an effective approach for detecting and mapping BIScV infections. Convolutional Neural Networks (CNNs) are among the most widely employed algorithms in remote sensing image classification. However, CNNs have some limitations in their ability to obtain global information dependency due to the convolution’s constrained receptive field in each layer. To address this challenge, the self-attention mechanism utilized in Vision Transformers (ViTs) was suggested in previous studies for achieving flexible global information dependency through facilitating communication among arbitrary pixels in images. As such, we developed a CNN-ViT-based deep learning algorithm (named “Scorch Mapper”), a pixel-based classifier, that utilizes both the functionality and capabilities of CNNs in capturing local visual characteristics and ViTs for acquiring long-range information dependency for the mapping of BIScV. We also compared the developed Scorch Mapper to several other CNN– and ViT-based algorithms, including a 2D CNN, ResNet, HybridSN, Swin Transformer, Efficient Net, CMT, InFormer, and Efficient Former. Our results demonstrated the superiority of the Scorch Mapper compared to other CNN– and ViT-based algorithms. Research findings also show that the Scorch Mapper is effective and can be applied over a wide area to support BIScV mapping and monitoring. Furthermore, the developed model opens a new window for future automatic BIScV mapping utilizing cutting-edge remote sensing algorithms and technologies.

Permalink: https://www.hzdr.de/publications/Publ-40198


Analysis of Next-Generation Sequencing Data in Phage Display Trials: Recycling Rare Earth Elements from Fluorescent Light Bulbs

Bloß, C.; Techert, G.; Bobeth, C.; Boelens, P.; Lederer, F.

Abstract

The recent acceleration of efforts in biomolecular probes and materials science is propelled by the application of phage surface display (PSD) technology. Yet, the identification process of best binding peptides is hampered by the limitations of traditional phage display. Growth-related library baises, target unrelated peptides and mutations often lead to the dominance of parasitic sequences and undocumented collapse of library diversity. Next Generation Sequencing (NGS) is a suitable complement to PSD, as it provides a deep insight into the sequence space of the biopanning rounds, displays content and visualizes and calculates the evolution of the phage library during the biopanning rounds. The aim of this work is to find meaningful and statistical proven ways to identify metal binding peptides in multiple trail phage display experiments with inorganic materials.

Keywords: Phage Display; Next-Generation Sequencing; Bioinformatics; Biotechnology; Resource Recycling; short-oral presentation

  • Lecture (Conference)
    7th International Symposium on Biosorption and Biodegradation/Bioremediation, 16.-20.06.2024, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-40196


Differential Expression Analysis of Next-Generation Sequencing Data in Phage Display Trials: A Bioinformatics Approach for Recycling Rare Earth Elements from Fluorescent Light Bulbs

Bloß, C.

Abstract

Recycling rare earths from recycled fluorescent powder from fluorescent tubes is at present not economically feasible. Phage surface display (PSD) technology pushes recent efforts in biomolecular probes and materials science. However, the limitations of traditional phage display hamper the identification of the best binding peptides. Growth-induced library construction, off-target peptides and mutations often lead to the dominance of parasitic sequences and undocumented collapse of library diversity. Next generation sequencing (NGS) is a suitable complement to PSD as it provides deep insight into the sequence space of biopanning rounds, displays content, visualizes, and calculates phage library evolution during biopanning rounds. Yet, each sword has two edges. Yet, each sword has two edges. The number of counts usually varies greatly between individual biopanning rounds and available reads are strongly differentially expressed. The aim of this work is to find meaningful and statistically validated ways to identify metal-binding peptides in multiple-trail phage display experiments with inorganic materials.

Keywords: Phage Display; Next-Generation Sequencing; Bioinformatics; Differential Expression Analysis; Presentation; Conference; Resource Recycling; Biotechnology; Population Genetics

  • Lecture (Conference)
    FK12 2024 - 8th Freiberger PhD Conference, 07.06.2024, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40195


8th Geology Of Ore Deposits (GOOD) Meeting: 17th−18th of March 2024, Freiberg - Abstract Volume

Cerny, J.; Guilcher, M.; Frenzel, M.

Abstract

8th Geology Of Ore Deposits (GOOD) Meeting: 17th−18th of March 2024, Freiberg - Abstract

  • Contribution to proceedings
    8th Geology Of Ore Deposits (GOOD) Meeting, 17.-18.03.2024, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40194


River network connectivity and phylogenetic diversity patterns of riverine fishes

Garcia Andrade, A. B.; Calabrese, J.

Abstract

We disentangle the role of connectivity in river network connectivity on the configuration of assemblage community and diversity of riverine fishes at the global scale.

Keywords: River networks; Connectivity; Riverine fishes

  • Invited lecture (Conferences)
    River Network Meeting CASUS 2024, 25.09.2024, Görlitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40193


The Danube fish dataset

Calabrese, J.; Garcia Andrade, A. B.; Tibor, E.; Apostolou, A.

Abstract

For the first time, we have compiled a comprehensive dataset on freshwater fishes from the Danube River, using open, public and unpublished information as sources.

Keywords: Danube River; Freshwater fishes; Europe

  • Lecture (Conference)
    River Network Meeting UFZ 2024, 14.05.2024, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40192


Regionální syntéza a aplikace moderní strukturní geologie ma staro-nová data pomáhá dešifrovat logiku rozmístění líthných pňů a greisenů ve východních Krušných horách

Cerny, J.; Thiele, S. T.; Guilcher, M.; Burisch-Hassel, M.; Lehmann, U.; Kaufmann, H.; Sonnabend, L.; Gutzmer, J.

Abstract

Oblast východního Krušnohoří se může pochlubit četnými ložisky lithia a cínu vázanými na greiseny a greisenové žíly nad tělesy menších granitových pňů, jako je například ložisko Zinnwald-Cínovec. Více než 90 % zdokumentovaných výskytů významných ložisek lithia v Krušných horách je spojeno s pozdními intruzemi (˜313-310 mil. let) uvnitř Altenbersko-Teplické kaldery. Tato prezentace ukazuje vliv transtenzní tektoniky na rozmístění a prostorové uspořádání malých granitových intruzí nad nimž vznikly graisenová ložiska s Li-Sn zrudněním. Při zkoumání zlomů v širší oblasti Altenbersko-Teplické a Tharandtské kaldery a současně vzniklých západočeských karbonských (středopennsylvánských) pánvích lze identifikovat velkorozměrovou složenou pull-apart strukturu. Náš model nabízí vhled do složitého tektonického rámce, který predikuje rozložení peraluminických granitů bohatých na Li a souvisejících Li-Sn greisenových systémů v oblasti Krušných hor.  

  • Invited lecture (Conferences)
    Innovatice Exploration - recomine SN-CZ-Plus, 29.-30.10.2024, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40190


CFD-Activities at HZDR – a short overview

Lucas, D.

Abstract

The need to optimise processes, e.g. in terms of energy consumption and product properties, is leading to an increasing demand from industry to be able to reliably predict multiphase flows or even to simulate them as a digital twin in parallel with industrial processes. Because of the large range of scales to be considered, the Euler-Euler approach is often the only feasible framework for medium and large industrial scales. Improving closure models and bringing together different modelling approaches for different scales of phase interfaces are important tasks to achieve a better reliability. For the latter, the flexible framework for OpenFOAM called MultiMorph is being developed at the HZDR. Improving closure models requires a better understanding of local phenomena that influence the interactions between phases. Enhanced possibilities for measurements (e.g. with high-speed cameras and ultra-fast X-ray tomography), growing feasibility of DNS for multiphase flows and the use of artificial intelligence open up new possibilities here. Some recent developments and requirements for future activities are discussed.

Keywords: CFD; Baseline model; MultiMorph

  • Lecture (others)
    Lectures at Politecnico di Milano, 10.07.2024, Milano, Italien

Permalink: https://www.hzdr.de/publications/Publ-40188


An Euler-Euler based CFD framework for multiphase flows combining resolved and unresolved structures

Lucas, D.; Schlegel, F.; Meller, R.; Krull, B.; Lehnigk, R.

Abstract

For simulations on multiphase flows in medium and large-scale industrial applications the Euler-Euler approach is most frequently used and often the only feasible one. In many flow situations, the involved interfaces cover a wide range of scales leading to different coexisting morphologies. Established simulation methods differ for the different interfacial scales. Large interfaces are represented in a resolved manner usually basing on the one fluid approach, e.g. Volume of Fluid (VOF) or Level Set. Unresolved (dispersed) flows are modelled using the two- or multi-fluid approach. A simulation method that requires less knowledge about the flow in advance would be desirable and should allow describing both interfacial structures – resolved and unresolved – in a single computational domain.
The morphology adaptive multifield two-fluid model MultiMorph, which is developed at HZDR, is able to handle unresolved and resolved interfacial structures coexisting in the computational domain with the same set of equations. An interfacial drag formulation for large interfacial structures is used to describe them in a VOF-like manner, while the usual closure models are applied for the unresolved phases. In addition, MultiMorph allows to simulate transitions between the morphologies. This concerns both physical transitions such as entrainment and detrainment as well as transitions resulting from a change in the size of the numerical mesh within the domain, if this changes the resolvability of a phase interface.
In the talk, the general approach and the handling of the transfer are presented and illustrated with simulation examples, including

  • a single bubble rising in a stagnant bubble column represented by a numerical grid with changing size,
  • bubbles rising through a stratified air-oil interface,
  • disintegration and accumulation in an oil-water phase inversion
  • complex flows at a column tray of a distillation column,
  • gas core formation in a swirl separator
  • air layer formation for drag reduction of a ship and
  • gas entrainment.

Keywords: CFD; MultiMorph; multiphase; multiscale; OpenFOAM

  • Invited lecture (Conferences)
    54th European Two.Phase Flow Group Meeting, 08.-11.09.2024, Dublin, Irland

Permalink: https://www.hzdr.de/publications/Publ-40187


Generalized Euler-Euler CFD-model for industrial multiphase flows

Lucas, D.

Abstract

For simulations on multiphase flows in medium and large-scale industrial applications the Euler-Euler approach is most frequently used and often the only feasible one. In many flow situations, the involved interfaces cover a wide range of scales leading to different coexisting morphologies. Established simulation methods differ for the different interfacial scales. Large interfaces are represented in a resolved manner usually basing on the one fluid approach, e.g. Volume of Fluid (VOF) or Level Set. Unresolved (dispersed) flows are modelled using the two- or multi-fluid approach. A simulation method that requires less knowledge about the flow in advance would be desirable and should allow describing both interfacial structures – resolved and unresolved – in a single computational domain. The morphology adaptive multifield two-fluid model MultiMorph, which is developed at HZDR, is able to handle unresolved and resolved interfacial structures coexisting in the computational domain with the same set of equations. An interfacial drag formulation for large interfacial structures is used to describe them in a VOF-like manner, while the usual closure models are applied for the unresolved phases. In addition, MultiMorph allows to simulate transitions between the morphologies. This concerns both physical transitions such as entrainment and detrainment as well as transitions resulting from a change in the size of the numerical mesh within the domain, if this changes the resolvability of a phase interface.

Keywords: CFD; multiphase; multiscale; morphology; MultiMorph

  • Invited lecture (Conferences)
    Particulate Flow Modelling Industrial Partner Meeting, 20.03.2024, Linz, Österreich

Permalink: https://www.hzdr.de/publications/Publ-40186


Structural Controls on the Emplacement of Li-Sn Granites in the Eastern Erzgebirge / Krušné Hory

Cerny, J.; Thiele, S. T.; Guilcher, M.; Burisch-Hassel, M.; Lehmann, U.; Kaufmann, H.; Sonnabend, L.; Gutzmer, J.

Abstract

The Eastern Erzgebirge region is home to several important Li-mica deposits found within granite formations, such as the Zinnwald-Cinovec deposit. More than 90% of the documented Li-mica occurrences in the Erzgebirge are associated with late-stage intrusions (approximately 313-310 Ma) within the Altenberg-Teplice caldera system. This study explores the impact of trans-tensional tectonics and related crustal-scale faults on the location and distribution of small stock-like granitic intrusions within this caldera system. By analyzing fault patterns in the larger Altenberg-Teplice and Tharandt calderas, along with the adjacent western Bohemian Carboniferous (Middle Pennsylvanian) basins, we identify a large-scale composite pull-apart structure. We propose a straightforward tectonic model involving various secondary and tertiary dilatant and transfer structures, which connect the primary Elbe Shear Zone in the northeast to the Pfahl or Danube shear zones in the southwest. This model suggests the formation of the largest Carboniferous pull-apart system in the Bohemian Massif. It provides valuable insights into the complex tectonic framework controlling the distribution and concentration of Li-rich peraluminous granites and associated Li-Sn greisen systems in the Erzgebirge region.

  • Invited lecture (Conferences)
    DOME SPP - Mineral Deposits of the Erzgebirge, Field Excursion, 21.-25.07.2024, Schwarzenberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40185


Hydrodynamics in a bubble column – Part 2: Three-phase flow

Sommer, A.-E.; Draw, M.; Wang, L.; Schmidtpeter, J.; Gatter, J.; Nam, H.; Eckert, K.; Rzehak, R.

Abstract

Multiphase computational fluid dynamics (CFD) simulation is a useful tool to study the hydrodynamics in a bubble column, if appropriate closure models are known. Systematic assessment of different models is an ongoing venture that benefits from improved validation data. The present study accumulates a database on three-phase flow experiments in a bubble column. This is achieved by using a combination of Particle Image Velocimetry and Shadowgraphy to measure the liquid velocity, solid velocity, solid concentration and gas dispersion properties simultaneously. This methodology is applied for different needle diameters, gas flow rates and particle concentrations.

A detailed description of the experimental setup can be found in XXX.

The experimental data (Table 1) described in this repository is structured into different folders and files as follows:
Level 1: Folders classified by measurement configuration: TW_Jg_X_Di_YYY_C_ZZZ as outlined in Table 1

  • TW = Identifier
  • Jg_X = Superficial gas velocity in mm/s
  • Di_YYY = Inner diameter of the needle in µm
  • C_ZZZ = Particle concentration * 100 in %

Level 2: Folders classified by measurement height: Z_XXX

  • Z_XXX = Measurement height in mm

Level 3: csv files classified by their analysis parameter:

  • Gas_Eg_ub_over_x.csv: Each csv file consists of five columns, namely the x-coordinate (in m), the gas holdup, the uncertainty of the gas holdup, the averaged bubble rising velocity (in m/s) and the corresponding uncertainty (in m/s).
  • Liquid_v_z_over_x.csv: Each csv file consists of three columns, namely the x-coordinate (in m), the averaged liquid velocity (in m/s) and the corresponding uncertainty (in m/s).
  • Solid_alpha_over_z.csv: Each csv file consists of three columns, namely the z-coordinate (in m), the averaged solid fraction and the corresponding uncertainty .
  • Solid_v_z_over_x.csv: Each csv file consists of three columns, namely the x-coordinate (in m), the averaged solid velocity (in m/s) and the corresponding uncertainty (in m/s).

Table 1: Overview of the measurement cases in this repository.

| ID  | Needle diameter [µm] | Superficial gas velocity [mm/s] | Particle concentration [vol%] |
|-----|----------------------|---------------------------------|-------------------------------|
| L1  | 200                  | 2                               | 0.05                          |
| L2  | 600                  | 2                               | 0.05                          |
| L3  | 200                  | 2                               | 0.1                           |
| L4  | 600                  | 2                               | 0.1                           |
| L5  | 200                  | 2                               | 0.15                          |
| L6  | 600                  | 2                               | 0.15                          |
| L7  | 200                  | 4                               | 0.05                          |
| L8  | 600                  | 4                               | 0.05                          |
| L9  | 200                  | 4                               | 0.1                           |
| L10 | 600                  | 4                               | 0.1                           |
| L11 | 200                  | 4                               | 0.15                          |
| L12 | 600                  | 4                               | 0.15                          |
| L13 | 200                  | 6                               | 0.05                          |
| L14 | 600                  | 6                               | 0.05                          |
| L15 | 200                  | 6                               | 0.1                           |
| L16 | 600                  | 6                               | 0.1                           |
| L17 | 200                  | 6                               | 0.15                          |
| L18 | 600                  | 6                               | 0.15                          |

Keywords: Particle Image Velocimetry (PIV); Shadowgraphy; Three-phase bubble column

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Permalink: https://www.hzdr.de/publications/Publ-40184


The promise of community-driven preprints in ecology and evolution

Noble, D. W.; Xirocostas, Z. A.; Wu, N. C.; Robin Martinig, A.; Almeida, R. A.; Bairos-Novak, K. R.; Balti, H.; Grant Bertram, M.; Bliard, L.; Brand, J. A.; Byrne, I.; Chan, Y.-C.; Clink, D. J.; Corbel, Q.; Correia, R. A.; Crawford-Ash, J.; Culina, A.; dBastiani, E.; Deme Gywa, G.; de Souza Leite, M.; Dhellemmes, F.; Dimri, S.; Marian Drobniak, S.; Elsy, A. D.; Everingham, S. E.; JL Gascoigne, S.; Grainger, M.; Hossack, G. C.; Anders Hovstad, K.; Ivimey-Cook, E. R.; Lloyd Jones, M.; Kačergytė, I.; Küstner, G.; Leibold, D. C.; Mair, M. M.; Mitchell Martin, J.; Mizuno, A.; Moodie, I. R.; Moreau, D.; ODea, R. E.; Orr, J. A.; Paquet, M.; Parajuli, R.; Pick, J. L.; Pottier, P.; Purgar, M.; Recio, P.; Roche, D. G.; Royauté, R.; Shafiei Sabet, S.; MG Segovia, J.; Simoes Silva, I. M.; Sánchez-Tójar, A.; Soares, B. E.; Szabo, B.; Takola, E.; Thoré, E.; Timilsina, B.; van Dis, N. E.; CEP Verberk, W.; JG Vriend, S.; Wild, K. H.; Williams, C.; Yang, Y.; Nakagawa, S.; Lagisz, M.

Abstract

Publishing preprints is quickly becoming commonplace in ecology and evolutionary biology. Preprints can facilitate the rapid sharing of scientific knowledge establishing precedence and enabling feedback from the research community before peer review. Yet, significant barriers to preprint use exist including language barriers, a lack of understanding about the benefits of preprints and a lack of diversity in the types of research outputs accepted (e.g., reports). Community driven preprint initiatives can allow a research community to come together to break down these barriers to improve equity and coverage of global knowledge. Here, we explore the first preprints uploaded to EcoEvoRxiv (n = 1216), a community-driven preprint server for ecologists and evolutionary biologists, to characterise preprint practices in ecology, evolution and conservation. Our perspective piece highlights some of the unique initiatives that EcoEvoRxiv has taken to break down barriers to scientific publishing by exploring the composition of articles, how gender and career stage influence preprint use, whether preprints are associated with greater open science practices (e.g., code and data sharing), and tracking preprint publication outcomes. Our analysis identifies areas that we still need to improve upon but highlight how community-driven initiatives, such as EcoEvoRxiv, can play a crucial role in shaping publishing practices in biology.

Keywords: ecology; evolution; preprints; publications; research

Permalink: https://www.hzdr.de/publications/Publ-40182


PIANOFORTE − Europäische Partnerschaft für Strahlenschutzforschung

Rauser, F.; Franzen, C.; Süptitz, G.; Blume, A.; Sachs, S.; Birschwilks, M.; Arnold, T.

Abstract

Die Europäische Partnerschaft für Strahlenschutzforschung PIANOFORTE hat die weitere Verbesserung des Strahlenschutzes in verschiedensten Themengebieten und die Koordinierung der europäischen Aktivitäten in Forschung, Infrastruktur und Sicherheit zum Ziel. Sie bildet mit inzwischen beinahe 100 Projektpartnern aus 22 europäischen Ländern ein breites Spektrum von strahlenschutzrelevanten Themen und Kompetenzen ab. Die Aktivitäten der Partnerschaft tragen zur Umsetzung der europäischen Politik im ­Strahlenschutz bei und sorgen für einen Wissens- und Ideenaustausch zwischen Forschung, Politik, Industrie und auch der Gesellschaft. Dies wird durch ein breites Spektrum an Maßnahmen, internationaler Zusammenarbeit und Abstimmung erreicht.

Keywords: EURATOM; Verbundforschung; Strahlenschutz

  • Open Access Logo StrahlenschutzPRAXIS 30(2024)4, 5-8
    ISSN: 0947-434 X

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Permalink: https://www.hzdr.de/publications/Publ-40180


The River Network Project

Colombo, E. H.; Garcia Andrade, A. B.; Ismail, I.; Calabrese, J.

Abstract

Rivers are hotspots of biodiversity that have already been heavily impacted by human activities and climate change on a global scale. With such anthropogenic pressures only expected to intensify in the future, it is crucial to develop science-based management policies to protect riverine biodiversity. However, there is currently no general framework for modeling and predicting biodiversity change in rivers from which effective management actions could be derived. The River Networks project leverages an interdisciplinary collaboration between CASUS and UFZ to construct a general, data-driven platform for riverine biodiversity analysis that combines hydrological and species community models to identify the key drivers of biodiversity change in rivers worldwide. The ultimate goal of the project is to predict biodiversity change given different climate change scenarios, while also identifying the interventions mostly likely to limit biodiversity loss.

Keywords: River networks; Global change forecast; Neutral models

  • Poster
    CASUS Science Day 2024, 19.12.2024, Görlitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40179


River networks driving phylogenetic fish diversity

Garcia Andrade, A. B.; Calabrese, J.

Abstract

Here, we evaluated how the structural connectivity of river networks drives phylogenetic diversity and relatedness of riverine fishes in North America.

Keywords: river networks; diversity patterns; North America

  • Lecture (Conference)
    BES MACRO Conference 2024, 10.-12.07.2024, Cardiff, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-40178


Transtensional tectonics control emplacement of lithium-tin granites in the Eastern Erzgebirge (Germany / Czech Republic)

Cerny, J.; Thiele, S. T.; Guilcher, M.; Burisch, M.; Lehmann, U.; Kaufmann, H.; Sonnabend, L.; Gutzmer, J.

Abstract

The Eastern Erzgebirge region contains several significant granite-related Li-mica deposits (e.g., Zinnwald-Cinovec). More than 90% of the known Li-mica occurrences of the Erzgebirge are related to late-stage intrusions (˜313-310 Ma) within the Altenberg-Teplice caldera system. In this contribution, we explore the role of transtensional tectonics and associated crustal-scale faults as the controlling factors for the emplacement and spatial distribution of small stock-like granitic intrusions within the Altenberg-Teplice Caldera. Examination of fault architectures within the wider region of Altenberg-Teplice and Tharandt calderas, and within the broadly contemporaneous western Bohemian Pennsylvanian basin (~314-312 Ma), reveals a large-scale composite pull-apart structure. This includes three pull-apart basins cleaved by a network of transform faults providing trans-crustal connectivity, which are preferentially hosting intrusive stocks and related mineralization. We propose a simplified mechanical model that invokes several second- and third-order dilatant and transfer structures linking the first-order Elbe Shear Zone in the northeast to the Pfahl or Danube shear zones in the southwest that have allowed the opening of this pull-apart system.

Our analysis provides insight into the intricate tectonic framework that controls the distribution and localization of Li-rich peraluminous granites and associated Li-Sn greisen systems in the Erzgebirge region, with possible applications elsewhere in the world. This approach brings a new exploration tool for identifying favorable locations for undiscovered Li-endowed granite stocks in the Eastern Erzgebirge and provides useful criteria for the exploration of Li-Sn granites in collapsed collisional orogens.

Keywords: Transtension; Erzgebirge; Elbe Shear Zone; Late-Variscan magmatism; Pull-apart

  • Lecture (Conference)
    SEG 2024 Conference: Sustainable Mineral Exploration and Development, 27.-30.09.2024, Windhoek International Convention, Namibia

Permalink: https://www.hzdr.de/publications/Publ-40177


Fishes in the net: The role of river network characteristics on fish diversity

Garcia Andrade, A. B.; Colombo, E. H.; Ismail, I.; Calabrese, J.

Abstract

Freshwater fishes are among the most restricted species worldwide because they are fully contained within fragmented networks of water bodies surrounded by land. Given that the natural fragmentation and isolation of these networks have been identified as a generator of the greatest diversity in this group, we need a deeper understanding of their role as drivers of fish diversity. Hints that the evolutionary history and distribution of fishes are closely linked to the geomorphological history of watersheds exist in the literature. For
example, some studies have shown that certain watershed traits such as river size, surface area, and natural fragmentation of watersheds are correlated with measures of species diversity. Despite this progress, how the complex interplay between river network structure, watershed characteristics, and species’ spatial ecologies drives diversification and biodiversity in freshwater fishes is not yet understood. Here, we combine a global fish occurrence database, a detailed, species-level phylogeny, and a novel dataset on river network structure and watershed traits to comprehensively reveal the determinants of freshwater fish biodiversity at the global
scale. The dataset encompasses 11,300+ species distributed across 2,000+ watersheds worldwide, representing approximately 60% of the global diversity of freshwater fishes. To characterize watershed heterogeneity and connectivity we first calculated novel metrics of river network structure including centralization and density, and combined them with geomorphological and climatic characteristics. We then related these variables to fish diversity metrics considering the spatial autocorrelation in the regression analyses. Our preliminary
findings indicate that fish diversity is jointly determined by environmental heterogeneity and river network connectivity, highlighting the necessity to account for network structure and characteristics when studying global biodiversity patterns of freshwater species.

Keywords: River networks; Global diversity patterns; Fish diversity

  • Poster
    Saxony meets Lower Silesia - Science Across Borders Conference, 17.-18.06.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40176


Role of transtensional tectonics in the emplacement of Li-Sn granites in the Eastern Erzgebirge / Krušné hory

Cerny, J.; Thiele, S. T.; Guilcher, M.; Burisch-Hassel, M.; Lehmann, U.; Kaufmann, H.; Sonnabend, L.; Gutzmer, J.

Abstract

The Eastern Erzgebirge area boasts numerous significant Li-mica deposits associated with granite formations, such as the Zinnwald-Cinovec deposit. Over 90% of the documented Li-mica occurrences in the Erzgebirge are linked to late-stage intrusions (˜313-310 Ma) within the Altenberg-Teplice caldera system. This study investigates the influence of trans-tensional tectonics and the corresponding crustal-scale faults on the placement and spatial arrangement of small stock-like granitic intrusions within this caldera system. Examining fault patterns in the broader Altenberg-Teplice and Tharandt calderas, and the contemporaneous western Bohemian Carboniferous (Middle Pennsylvanian) basins, we identify a large-scale composite pull-apart structure. We propose a simple tectonic model involving various dilatant and transfer structures of secondary and tertiary orders, linking the primary Elbe Shear Zone in the northeast to the Pfahl or Danube shear zones in the southwest, to enable the formation of the largest Carboniferous pull-apart system in Bohemian Massif. Our model offers insight into the complex tectonic framework dictating the distribution and concentration of Li-rich peraluminous granites and associated Li-Sn greisen systems in the Erzgebirge region.

Keywords: Eastern Erzgebirge; Zinnwald-Cinovec deposit; Altenberg-Teplice caldera; Tharandt caldera; Pull-apart; Li-mica deposits

  • Lecture (Conference)
    GeoSaxonia 2024 – Annual Meeting of the DGGV, 13.-26.09.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-40175


Data publication: Ge epitaxy at ultra-low growth temperatures enabled by a pristine growth environment

Wilflingseder, C.; Aberl, J.; Prado Navarrete, E.; Hesser, G.; Groiss, H.; Liedke, M. O.; Butterling, M.; Wagner, A.; Hirschmann, E.; Corley-Wiciak, C.; Zoellner, M.; Capellini, G.; Fromherz, T.; Brehm, M.

Abstract

The data set consists of the raw and analysis data. Positron annihilation lifetime spectroscopy depth profiles were measured at the positron ELBE during the PI beamtime on November 2023 (POS23203233). MBE deposited Ge layers at temperatures of 100°C - 350°C have been evaluated concerning defect microstructure. The most dominant defect, namely Ge vacancy, has been evidenced independently on the temperature conditions. The results support the main claim of the manuscript, feasibility of the low temperature growth approach to Ge.

Keywords: Germanium; defects; positron annihilation spectroscopy; MBE; low temperature growth; Ge-vacancy

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Permalink: https://www.hzdr.de/publications/Publ-40173


Core-corona decomposition of compact (neutron) stars compared to NICER data including XTE J1814-338

Zöllner, R.; Kämpfer, B.

Abstract

A core-corona decomposition of compact (neutron) star models is compared to recent NICER data of masses and radii. It is in particular interesting to capture the outlier XTE~J1814-338. Instead of integrating the TOV equations from the center to surface, we follow here another pathway by accommodating all uncertainties of the equation(s) of state (EoS) at supra-nuclear density or/and an unknown dark matter admixture in a parameterization of the core by its radius rx, the included mass mx and the pressure px at rx. The corona, which may be dubbed also envelope or halo or outer crust, is assumed to be of standard-model matter where the EoS is supposed to be faithfully known.

Permalink: https://www.hzdr.de/publications/Publ-40172


PIANOFORTE - Europäische Partnerschaft für Strahlenschutzforschung

Franzen, C.; Rauser, F.; Süptitz, G.; Blume, A.; Sachs, S.; Birschwilks, M.; Arnold, T.

Abstract

Die kofinanzierte Europäische Partnerschaft für Strahlenschutzforschung PIANOFORTE hat im Juni 2022 ihre Arbeit aufgenommen. Das von
EURATOM und den Regierungen der beteiligten Länder und Regionen finanzierte Programm soll zu einer weiteren Verbesserung des
Schutzes der Bevölkerung und der Umwelt vor schädlichen Wirkungen ionisierender Strahlung beitragen. Die Partnerschaft bringt 58 Partner
aus 22 Ländern der Europäischen Union, dem Vereinigten Königreich und Norwegen zusammen und wird vom französischen Institut für
Strahlenschutz und nukleare Sicherheit (IRSN) koordiniert. Die Partnerschaft baut auf früheren Arbeiten auf - insbesondere auf den
Ergebnissen des 2020 ausgelaufenen europäischen Programms CONCERT.
Durch die Forschungstätigkeiten wird PIANOFORTE zur Umsetzung der europäischen Politik beitragen, z. B. zum europäischen Plan zur
Krebsbekämpfung, zum grünen Pakt für Wachstum und zur Umsetzung der Verringerung der industriellen und natürlichen Risiken.
Die Partnerschaft fördert multidisziplinäre Forschung und Innovation, unterstützt Aus- und Weiterbildungsmaßnahmen, fördert die
gemeinsame Nutzung von Infrastrukturen und vernetzt Forschende, Behörden und Interessengruppen einschließlich der Zivilgesellschaft.
Die Priorisierung der Schwerpunktthemen wird partizipativ vorgenommen. Dazu wurden alle sechs Europäischen Strahlenschutzplattformen,
die Programmverantwortlichen und –manager der jeweiligen Länder und Regionen, der Beirat aus Stakeholdern und Beratern und eine
große Gruppe externer Interessenvertreter aufgefordert, zu den vorgeschlagenen Themen Stellung zu nehmen und diese zu priorisieren.
Im Rahmen dieser Partnerschaft werden mindestens drei offene Ausschreibungen zu Projektanträgen veröffentlicht, die der gesamten
europäischen Forschungsgemeinschaft im Bereich des Strahlenschutzes offenstehen.
Die Partnerschaft hat vorerst eine Laufzeit von 5 Jahren. Das geschätzte Budget beträgt 45 Millionen Euro, wovon 65% von der
Europäischen Union und 35% von den Partnerländern und - regionen finanziert werden.

Keywords: Strahlenschutz; EURATOM

  • Open Access Logo Invited lecture (Conferences)
    Jahrestagung 2024 - Fachverband für Strahlenschutz e.V., 16.-20.09.2024, Berlin, Deutschland
    ISSN: 1013-4506

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Permalink: https://www.hzdr.de/publications/Publ-40171


A contribution to 3D bubble tracking

Wang, L.; Ma, T.; Hessenkemper, H.

Abstract

Reliable Lagrangian 3D tracking of individual bubble swarm members allows a deeper understanding of hydrodynamic bubble-bubble interactions and their collective rise. For multi-view measurements, we have recently developed such a tracking method (Hessenkemper et al., 2024), which is able to track deformable bubbles with low to moderate view obstruction through the bubbles to each other. In the present work, we aim to further enhance the 3D tracking performance by incorporating 2D temporal information in the form of previously established 2D tracks in each view. The new 3D tracking method is able to disambiguate cross-view object associations at each time step by using the 2D track information accumulated over time. In addition, the 2D track information is used in two post-processing steps to improve the completeness of established 3D trajectories. Compared to the previous 3D tracking method, the extended 3D tracking framework shows noticeable improvements in tracking ability, accuracy and completeness of trajectories.

Keywords: bubbly flows; 3D Lagrangian bubble tracking; deformable bubble

  • Lecture (Conference)
    HZDR Doctoral Seminar 2024, 25.-27.11.2024, Pilsen, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-40169


Lateral forces acting on single bubbles rising near a wall w/ and w/o shear flows

Wang, L.; Ma, T.; Lucas, D.; Eckert, K.; Hessenkemper, H.

Abstract

Understanding the interaction between the near-wall bubble moving in a shear flow and the liquid phase is essential for the design and optimization of multiphase flow systems. Previous studies have focused either on the hydrodynamic force acting on wall-free bubbles in shear flow or on the force acting on single bubbles rising in the vicinity of the wall in stagnant surrounding liquid. However, the combination of wall and shear field acting on bubbles, especially ellipsoidal bubbles with high bubble Reynolds numbers, has not been sufficiently investigated. Therefore, this work considers both forces acting on single ellipsoidal bubbles for various bubble Reynolds numbers (500 ≤ Re ≤ 1200) and bubble-to-wall distances. By tracking bubbles using high-speed cameras, bubble features and motion were experimentally obtained. The experiments are first conducted in stagnant water, focusing on resulting wall coefficient C_W of ellipsoidal bubbles over different bubble-to-wall distances. Furthermore, a stable shear flow was generated in subsequent experiments and the modification of C_W of a near-wall bubble in a shear flow is investigated. A more accurate C_W (involved in the wall force modeling) can generally contribute to more reliable results for Eulerian simulations of bubbly flows.

Keywords: Wall force coefficient; Vertical wall; Lift force coefficient; Bubbly flow; Single bubble

  • Poster
    20th Multiphase Flow Workshop - Conference and Short Course (MPF2024), 11.-15.11.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-40168


Wall force coefficient of deformable bubbles rising near a vertical wall in stagnant water

Wang, L.; Ma, T.; Lucas, D.; Eckert, K.; Hessenkemper, H.

Abstract

The motion of bubbles rising near a vertical wall is influenced by the wall-induced hydrodynamic force, which is critical for understanding and modeling multiphase flows. While the behavior of spherical bubbles has been studied extensively, the wall force coefficient (C_W) for deformable, ellipsoidal bubbles at high bubble Reynolds numbers in stagnant water remains underexplored. This work experimentally investigates the wall force acting on single ellipsoidal bubbles rising near a vertical wall across a range of bubble Reynolds numbers (500-1200) and bubble-to-wall distances. Using high-speed cameras, bubble trajectories and deformation were tracked to determine wall force coefficient (C_W). These results contribute to improved wall force modeling, which is essential for accurate Eulerian simulations of bubbly flows.

Keywords: Wall force coefficient; Vertical wall; Bubbly flows; Single deformable bubble

  • Lecture (Conference)
    16 th International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering (GLS-16), 02.-05.09.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-40167


Controlling Supercritical CO₂ Power Cycles for Tomorrow's Energy Demand

Velde, J.; Fogel, S.; Unger, S.; Hampel, U.

Abstract

Supercritical CO₂ power cycles are highly efficient and can be constructed as compact plants. In order to utilise the power cycles for the stabilisation of the power grid in the absence of renewable energy, specific control mechanisms are required. These must be capable of rapid turn-on and shut-off, as well as functioning in partial load. Furthermore, the control mechanisms should be able to stabilise the temperature and pressure at critical points within the cycle, and respond to fluctuations in power demand.

Involved research facilities

  • TOPFLOW Facility
  • Poster
    HZDR DocSeminar 2024, 25.-27.11.2024, Plzeň, Česká republika

Permalink: https://www.hzdr.de/publications/Publ-40165


Euler-Euler Simulation of a Bubble Column Flow up to High Gas Content

Draw, M.; Rzehak, R.

Abstract

CFD simulations of multiphase flows are feasible on industrial scales using the Eulerian framework of interpenetrating continua. However, the necessary closure models to account for the interfacial interactions are often restricted to dilute conditions, limiting their applicability in an industrial context. This study investigates homogeneous flow in a bubble column up to a gas holdup of 50%. For low to medium gas holdup below ~20% the good performance of an established baseline model is confirmed. In this range, the mixture pressure gradient is decisive in determining the relative velocity, resulting in good predictions without considering a swarm correction to the drag force. At higher gas holdup, however, such a swarm correction becomes necessary, for which several proposals from the literature are evaluated. In addition, the lift force influences the gas fraction profile depending on the bubble size. The resulting profile shape has a significant impact on the liquid circulation inside the column. If the profile is peaked near the walls, the liquid flow remains moderate, while a center-peaked profile strongly boosts the liquid velocity. This is shown to correspond with one mechanism for transition from homogeneous to heterogeneous flow proposed in the literature.

Keywords: Euler-Euler simulation; swarm effects; bubble column

  • Lecture (Conference)
    16th Internation Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering, 02.-05.09.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-40162


Simulation of mass transfer in bubbly flows – Different configurations and varying bubble composition

Rzehak, R.; Khan, H.

Abstract

Mass transfer in bubbly flows is important in many engineering applications. Simulation of such processes on technical scales is feasible by the Euler-Euler two-fluid model, which relies on suitable closure relations describing interfacial exchange processes. In comparison with the pure fluid dynamics of bubbly flows however, modeling and simulation of bubbly flows including mass transfer is significantly less developed.
In particular, previous simulation studies have focused almost exclusively on absorption in bubble columns without liquid flow. However, recent experiments on single bubbles suggest that the simultaneous desorption of dissolved inert gases in general cannot be neglected. This requires consideration of changing bubble composition in addition to bubble size. In addition imposing a liquid flow allows a steady state to be achieved also when the mass transfer is accompanied by a chemical reaction, which greatly simplifies the analysis of reactive mass transfer problems.
Therefore, the present study first considers a larger variety of conditions including desorption and counter-current (downward) flow for which experimental data for a first comparison are available from the literature. Then a simple sandbox test case is used to illustrate how the bubble composition may be tracked as a secondary property in addition to bubble size within a population balance framework. An analytical solution can be found for this test case, which facilitates verification of the software implementation of the discretized population balance equation.
In this way, further building blocks for a more complete numerical treatment of mass transfer in bubbly flows are now available. A thorough validation for realistic applications however requires yet further experimental work to provide suitable measurement data.

Keywords: Euler-Euler simulation; mass-transfer; absorption; population-balance; co- and countercurrent flow; bubble column

  • Lecture (Conference)
    15th International Conference on Industrial Applications of Computational Fluid Dynamics, 10.-13.06.2024, Trondheim, Norway

Permalink: https://www.hzdr.de/publications/Publ-40161


Data publication: Novel correlative microscopy approach for nano-bio interface studies of ultrafine particle-induced lung epithelial cell damage

Podlipec, R.; Hlawacek, G.

Abstract

Raw data used in the figures and plots

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Permalink: https://www.hzdr.de/publications/Publ-40160


A framework to integrate bubble-particle aggregates and flotation-kinetics in Eulerian multiphase CFD

Rzehak, R.; Draw, M.

Abstract

Simulation of multiphase flows up to industrial scales is presently feasible only by the Eulerian multi-fluid framework in which all phases are treated as interpenetrating continua. In applications to flotation processes one of these phases consists of aggregates of bubbles and attached particles. Formation of these aggregates is governed by the kinetics of particle bubble attachment and detachment and their fluid-dynamic behavior likely depends on the attached particles and differs from that of pure bubbles. The present work proposes a framework suitable to account for these phenomena by considering the aggregates as a two-component mixture of a reactive particle- and an inert bubble-species. Methods for reactive mass transfer, which are available in major CFD codes, can then be adapted to describe flotation kinetics. Demonstration cases with simplified models are shown to verify the implementation of the framework in OpenFOAM and to illustrate possible applications in flotation.

Keywords: Euler-Euler simulation; flotation; particle-bubble-aggregates; particle-bubble-attachement; flotation-kinetics

  • Lecture (Conference)
    2nd International RFC Symposium, 09.-11.04.2024, Trandheim, Norway

Permalink: https://www.hzdr.de/publications/Publ-40159


Data publication: Contribution of black carbon and desert dust to aerosol absorption in the atmosphere of the Eastern Arabian Peninsula

Podlipec, R.; Lohmann, S.; Hlawacek, G.

Abstract

raw helium ion microscopy images used in the publication

Keywords: helium ion microscopy; him

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Permalink: https://www.hzdr.de/publications/Publ-40158


Euler-Euler Simulation of Two- and Three-Phase Flow at High Gas Content

Rzehak, R.

Abstract

Progress on Eulerian simulations of two- and threephase flows relevant to applications such as flotation is presented. Focus in such applications is often on situation with high conent of disperse phases, where modeling is still a challenge. For two-phase flows a better understanding has been achived recently, while for three-phase flows further effects may be present which are yet rather unexplored.

Keywords: Euler-Euler simulation; swarm effects; bubble column; slurry bubble column

  • Lecture (others)
    3rd Topic-Workshop RESOURCE AND ENERGY EFFICIENCY, 21.-22.02.2024, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-40157


3D tracking of dense deformable bubbles to study the life cycle of bubble clusters

Hessenkemper, H.; Lucas, D.; Ma, T.

Abstract

The evolution of bubble clusters is a fundamental aspect in the study of the collective dynamics of gas
bubbles rising in a liquid environment, which requires Lagrangian tracking of the individual bubbles in the
measurement volume. To meet this requirement, we present a new strategy for tracking deformable bubbles in
multi-view measurements. Using dedicated deep learning models, we are able to detect and track bubbles in 3D
under moderate to high image coverage, which still corresponds to rather dilute cases of 1-2% gas fraction.
We apply our method to dispersed bubbly fl ows with ellipsoidal and wobbling bubbles recorded in an octagonal
bubble column fi lled with water. The acquired 3D trajectories allow us to identify bubble clusters together with
important cluster characteristics such as their size, lifetime and the arrangement of their individual members.
We also study the rising velocity of individual bubbles in a cluster and aim to relate this to the identifi ed cluster
characteristics.

  • Lecture (Conference)
    1st European Fluid Dynamics Conference, 16.-20.09.2024, Aachen, Germany

Permalink: https://www.hzdr.de/publications/Publ-40156


Frustrated Synchronization of the Kuramoto Model on Complex Networks

Ódor, G.; Deng, S.; Kelling, J.

Abstract

We present a synchronization transition study of the locally coupled Kuramoto model on extremely large graphs. We compare regular 405 and 1004 lattice results with those of 12,0002 lattice substrates with power-law decaying long links (ll). The latter heterogeneous network exhibits ds=4 spectral dimensions. We show strong corrections to scaling and mean-field type of criticality at d=5, with logarithmic corrections at d=4 Euclidean dimensions. Contrarily, the ll model exhibits a non-mean-field smeared transition, with oscillating corrections at similarly high spectral dimensions. This suggests that the network heterogeneity is relevant, causing frustrated synchronization akin to Griffiths effects.

Keywords: synchronization; Kuramoto; criticality; spectral dimension

Involved research facilities

  • Data Center

Permalink: https://www.hzdr.de/publications/Publ-40155


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