Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41709 Publications

Tailoring pulsed laser deposition fabricated copper oxide film by controlling plasma parameters

Volfová, L.; Irimiciuc, S. A.; Chertopalov, S.; Hruska, P.; Cizek, J.; Vondracek, M.; Novotny, M.; Butterling, M.; Liedke, M. O.; Wagner, A.; Lancok, J.

Abstract

Various copper oxide stoichiometries have been grown by Pulsed Laser Deposition (PLD) on MgO (100). The role of oxygen pressure on the structural and physical properties of the films was investigated in the 1·10 –5 Pa – 1 Pa range. Positron annihilation spectroscopy revealed positrons trapped at vacancies and large vacancy clusters with lifetimes ranging from 400 ps to 500 ps. Different stoichiometries were found to be dominated by characteristic vacancies. Single copper vacancies V Cu are found for CuO phase with good indication for p-type applications while for the Cu 2 O complexes of copper vacancies coupled with oxygen vacancies (V Cu + V O and V Cu + 2V O ) are seen. Particular O 2 atmosphere conditions induce a mixture of copper oxide phases with the CuO crystals growing on top of Cu 2 O films. The deposition process was monitored with in situ diagnostic techniques based on optical emission spectroscopy and Langmuir probe method. The kinetics of the plasma during the deposition process are well correlated with the properties of the deposited films.
The monitoring tools define clear energetic threshold for the formation of CuO or Cu 2 O phases.

Keywords: pulsed laser deposition; copper oxide; defects; in situ plasma monitoring

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Permalink: https://www.hzdr.de/publications/Publ-34879


Characterization of the binding behavior of specific cobalt- and nickel ion-binding peptides identified by phage surface display

Matys, S.; Morawietz, L.-M.; Lederer, F.; Pollmann, K.

Abstract

In recent years, the application focus of phage surface display (PSD) technology has been extended to the identification of metal ion-selective peptides. In previous studies, two phage clones - a nickel-binding one with the peptide motif CNAKHHPRCGGG and a co-balt-binding one with the peptide motif CTQMLGQLCGGG - were isolated and their binding ability to metal-loaded NTA agarose beads was investigated. Here, the free cyclic peptides are characterized by UV/VIS spectroscopy and with respect to their binding capacity for the respective target ion as well as in crossover experiments for the other ion by isothermal titration calorimetry (ITC) in different buffer systems. This revealed differences in selectivity and affinity. While the cobalt-specific peptide is very sensitive to different buffers, but has a 20-fold higher affinity for cobalt and nickel under suitable conditions, the nickel-specific peptide binds more moderately and robustly in different buffers, but selectively only nickel.

Keywords: phage surface display; biopanning; metal binding peptides; nickel; cobalt; isothermal titration calorimetry

Permalink: https://www.hzdr.de/publications/Publ-34878


Visualisation of torsional modes with contactless inductive flow tomography

Molenaar, P.; Wondrak, T.; Jacobs, R. T.; Sonntag, S.; Krauthäuser, H. G.

Abstract

The contactless inductive flow tomography is a procedure that enables the reconstruction of the global three-dimensional flow structure of an electrically conducting fluid by measuring the flow-induced perturbation of an applied static magnetic field and by subsequently solving the associated linear inverse problem. The method enables the visualisation of the dynamics of a large-scale circulation in the modified Rayleigh-Bénard experiment.

Keywords: flow measurement; ontactless inductive flow tomography

  • Lecture (Conference)
    20th International IGTE Symposium 2022 on Computational Methods in Electromagnetics and Multiphysics, 18.-21.09.2023, Graz, Österreich

Permalink: https://www.hzdr.de/publications/Publ-34877


A Novel 2-Metagene Signature to Identify High-Risk HNSCC Patients amongst Those Who Are Clinically at Intermediate Risk and Are Treated with PORT

Patil, S. G.; Linge, A.; Hiepe, H.; Grosser, M.; Lohaus, F.; Gudziol, V.; Kemper, M.; Nowak, A.; Haim, D.; Tinhofer, I.; Budach, V.; Guberina, M.; Stuschke, M.; Balermpas, P.; Grün, J. V. D.; Schäfer, H.; Grosu, A.-L.; Abdollahi, A.; Debus, J.; Ganswindt, U.; Belka, C.; Pigorsch, S.; Combs, S. E.; Boeke, S.; Zips, D.; Jöhrens, K.; Baretton, G. B.; Baumann, M.; Krause, M.; Löck, S.

Abstract

Abstract: (1) Background: Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) who are at biologically high risk for the development of loco-regional recurrences af-ter postoperative radiotherapy (PORT) but at intermediate risk according to clinical risk factors may benefit from additional concurrent chemotherapy. In this matched-pair study, we aimed to identify a corresponding predictive gene signature. (2) Methods: Gene expression analysis was performed on a multicentre retrospective cohort of 221 patients that were treated with postoper-ative radiochemotherapy (PORT-C) and 283 patients that were treated with PORT alone. Propen-sity score analysis was used to identify matched patient pairs from both cohorts. From differen-tial gene expression analysis and Cox regression, a predictive gene signature was identified. (3) Results: 108 patient matched patient pairs were selected. We identified a 2-metagene signature that stratified patients into risk groups in both cohorts. The comparison of the high-risk patients between the two types of treatment showed higher LRC after treatment with PORT-C (p<0.001), which was confirmed by a significant interaction term in Cox regression (p=0.027), i.e. the 2-metagene signature was indicative for the type of treatment. (4) Conclusion: We have identi-fied a novel gene signature that may be helpful to identify patients with high-risk HNSCC amongst those at intermediate clinical risk treated with PORT, who may benefit from additional concurrent chemotherapy.

Keywords: head and neck squamous cell carcinoma; gene signature; postoperative radiotherapy; postoperative radiochemotherapy; propensity score matching

Permalink: https://www.hzdr.de/publications/Publ-34875


Investigation of complex electrical properties of concrete: A numerical model analysis

Nurjahan, T.; Schleicher, E.; de Assis Dias, F.; Hampel, U.

Abstract

Electrical impedance spectroscopy (EIS) is a powerful technique and observed to be more sensitive to complex composite and hydration which provides the estimated solution to our questions. Therefore, this letter deals with some of the preliminary results of the research. It reflects upon studying the complex electrical properties of the cementitious material through the numerical analysis over the range of 1 Hz to 10 MHz frequencies for dry and moist concrete samples.

Keywords: electrical impedance spectroscopy; complex electrical properties; moisture; Nyquist plots

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Permalink: https://www.hzdr.de/publications/Publ-34872


Controllable electrostatic manipulation of structure building blocks in noble metal aerogels

Wei, W.; Hübner, R.; Georgi, M.; Wang, C.; Wu, X.; Eychmüller, A.

Abstract

The important role of structure homogeneity in three-dimensional network nanostructures serving as noble metal aerogels (NMAs) has attracted extensive attention in the field of electrochemistry in the last two decades, whereas a comprehensive study of tailoring skeleton units and element distributions in NMAs is still lacking. Herein, a new modulation strategy to easily prepare multiscale NMAs with tunable composition is developed by utilizing the electrostatic interaction between oppositely charged colloidal metal nanoparticles. The modulation rule of the chemical distribution in bimetallic aerogels leads to the construction of the as-tailored double skeleton aerogels for the first time. Considering their specific structures, the intrinsic and exceptional catalytic and electrocatalytic performances of NMAs were investigated. This study optimizes the structure homogeneity of noble metal aerogels by investigating nanoparticle–ligand interactions and provides further proof of their exceptional electrocatalytic
capabilities.

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Permalink: https://www.hzdr.de/publications/Publ-34871


Homogenization and short-range chemical ordering of Co-Pt alloys driven by the grain boundary migration mechanism

Pedan, R.; Makushko, P.; Dubikovskyi, O.; Bodnaruk, A.; Burmak, A.; Sidorenko, S.; Voloshko, S.; Kalita, V.; Hübner, R.; Makarov, D.; Vladymyrskyi, I.

Abstract

Binary magnetic alloys like Co-Pt are relevant for applications as components of magnetic exchange coupled composites. Numerous approaches exist to tune the coercive field of Co-Pt alloys primarily relying on hightemperature processing aiming to realize chemically long-range ordered phases. The peculiarity of Co-Pt is that large coercive field and magnetic anisotropy can be achieved even in chemically disordered alloys relying on short-range order. Here, we study alloying of Co-Pt from bilayers of Pt(14 nm) Co(13 nm) at temperatures up to 550 degС, where bulk diffusion processes are suppressed and the dominant diffusion mechanism is grain boundary migration. We demonstrate that grain boundary diffusion mechanism can lead to the realization of a homogeneous yet chemically disordered Co56Pt44 alloy at temperatures of 500 degС and higher. A pronounced increase of the coercive field for samples processed at temperatures higher than 400 degС is attributed to short-range ordering. With this work, we pinpoint the grain boundary diffusion as the mechanism responsible not only for the homogenization of binary alloy films but also as a driving force for the realization of short-range order in Co-Pt. Our results motivate further research on grain boundary diffusion as a mechanism to realize chemically long-range ordered phases in Co-Pt alloys.

Keywords: grain boundary diffusion; magnetic thin films; short-range chemical order; Co-Pt alloy

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Permalink: https://www.hzdr.de/publications/Publ-34870


Pickering interfacial catalysts for asymmetric organocatalysis

Sun, Z.; Jurica, J.; Hübner, R.; Wu, C.

Abstract

Proline-catalyzed aldol reactions have been developed as an important toolbox for the synthesis of valuable chiral intermediates, giving birth to asymmetric organocatalysis. Despite progress, their current applications are generally performed in highly polar solvents that are either difficult to remove or with low substrate/product solubility. In addition, prolines are often used as homogeneous organocatalysts in these solvents, thus, the recycling of catalyst for reuse is also challenging. To solve these problems, we develop a proline-based Pickering emulsion for asymmetric aldol reactions with high reactivity and selectivity. The emulsion was stabilized by proline-functionalized silica nanoparticles that are not only highly active in the presence of water but also easily recycled after the operation. Interestingly, their high stereoselectivity was not compromised after multiple reuse, i.e., >86 ee (enantiomeric excess) in the first and second use. With this demonstration, we prove the concept that efficient and selective aldol reactions are enabled by proline-based Pickering emulsions, which is a great and continuous contribution to the field of asymmetric organocatalysis.

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Permalink: https://www.hzdr.de/publications/Publ-34869


Artificially sporulated Escherichia coli cells as a robust cell factory for interfacial biocatalysis

Sun, Z.; Hübner, R.; Li, J.; Wu, C.

Abstract

The natural bacterial spores have inspired the development of artificial spores, through coating cells with protective materials, for durable whole-cell catalysis. Despite attractiveness, artificial spores developed to date are generally limited to a few microorganisms with their natural endogenous enzymes, and they have never been explored as a generic platform for widespread synthesis. Here, we report a general approach to designing artificial spores based on Escherichia coli cells with recombinant enzymes. The artificial spores are simply prepared by coating cells with polydopamine, which can withstand UV radiation, heating and organic solvents. Additionally, the protective coating enables living cells to stabilize aqueous-organic emulsions for efficient interfacial biocatalysis ranging from single reactions to multienzyme cascades. Furthermore, the interfacial system can be easily expanded to chemoenzymatic synthesis by combining artificial spores with metal catalysts. Therefore, this artificial-spore-based platform technology is envisioned to lay the foundation for nextgeneration cell factory engineering.

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Permalink: https://www.hzdr.de/publications/Publ-34868


Importance of long-term follow up to address long-term effectiveness and toxicity of radiotherapy

Schneider, M.; Linge, A.; Krause, M.; Baumann, M.

Abstract

Modern radiotherapy and advances in systemic treatments are
leading to higher tumour control rates and longer survival rates,
thereby the number of long-term survivors of malignant tumours
is increasing. Therefore, minimising late and very late side
effects including radiation-induced secondary malignancies is par-
ticularly important. Accurate quantification of such sequelae is
only possible through very long, optimistically lifelong follow-up
of patients and comprehensive cancer registers

Keywords: none

Permalink: https://www.hzdr.de/publications/Publ-34867


Plasticity within Aldehyde Dehydrogenase-Positive Cells Determines Prostate Cancer Radiosensitivity

Schwarz, F. M.; Schniewind, I.; Besso, M. J.; Lange, S.; Linge, A.; Patil, S. G.; Löck, S.; Klusa, D.; Dietrich, A.; Voss-Böhme, A.; Nowrouzi, A.; Krause, M.; Dubrovska, A.; Kurth, I.; Peitzsch, C.

Abstract

Tumor heterogeneity and cellular plasticity are key determinants of tumor progression, metastatic spread, and therapy
response driven by the cancer stem cell (CSC) population. Within the current study, we analyzed irradiation-induced
plasticity within the aldehyde dehydrogenase (ALDH)-positive (ALDH+) population in prostate cancer. The radiosensitivity of
xenograft tumors derived from ALDH+ and ALDH-negative (ALDH-) cells was determined with local tumor control analyses
and demonstrated different dose-response profiles, time to relapse, and focal adhesion signaling. The transcriptional
heterogeneity was analyzed in pools of 10 DU145 and PC3 cells with multiplex gene expression analyses and illustrated a
higher degree of heterogeneity within the ALDH+ population that even increases upon irradiation in comparison with ALDH-
cells. Phenotypic conversion and clonal competition were analyzed with fluorescence protein-labeled cells to distinguish
cellular origins in competitive three-dimensional cultures and xenograft tumors. We found that the ALDH+ population
outcompetes ALDH- cells and drives tumor growth, in particular upon irradiation. The observed dynamics of the cellular state
compositions between ALDH+ and ALDH- cells in vivo before and after tumor irradiation was reproduced by a probabilistic
Markov compartment model that incorporates cellular plasticity, clonal competition, and phenotype-specific radiosensitivities.
Transcriptional analyses indicate that the cellular conversion from ALDH- into ALDH+ cells within xenograft tumors under
therapeutic pressure was partially mediated through induction of the transcriptional repressor SNAI2. In summary,
irradiation-induced cellular conversion events are present in xenograft tumors derived from prostate cancer cells and may be
responsible for radiotherapy failure. IMPLICATIONS: The increase of ALDH+ cells with stem-like features in prostate
xenograft tumors after local irradiation represents a putative cellular escape mechanism inducing tumor radioresistance.

Keywords: aldehyde dehydrogenase; genetics; human; male; prostate tumor; radiation tolerance; tumor recurrence; aldehyde dehydrogenase; neplasm recurrence; local

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Permalink: https://www.hzdr.de/publications/Publ-34866


Unveiling the Zero-Phonon Line of the Boron Vacancy Center by Cavity-Enhanced Emission

Qian, C.; Villafañe, V.; Schalk, M.; Astakhov, G.; Kentsch, U.; Helm, M.; Soubelet, P.; Wilson, N. P.; Rizzato, R.; Mohr, S.; Holleitner, A. W.; Bucher, D. B.; Stier, A. V.; Finley, J. J.

Abstract

Negatively charged boron vacancies (VB−) in hexagonal boron nitride (hBN) exhibit a broad emission spectrum
due to strong electron−phonon coupling and Jahn−Teller mixing of electronic states. As such, the direct measurement of the zero-
phonon line (ZPL) of VB− has remained elusive. Here, we measure the room-temperature ZPL wavelength to be 773 ± 2 nm by
coupling the hBN layer to the high-Q nanobeam cavity. As the wavelength of cavity mode is tuned, we observe a pronounced
intensity resonance, indicating the coupling to VB−. Our observations are consistent with the spatial redistribution of VB−
emission. Spatially resolved measurements show a clear Purcell effect maximum at the midpoint of the nanobeam, in accord with
the optical field distribution of the cavity mode. Our results are in good agreement with theoretical calculations, opening the way to using VB− as cavity spin−photon interfaces.

Keywords: 2D materials; Spins; hBN defect emitter; cavity-emitter coupling

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Permalink: https://www.hzdr.de/publications/Publ-34865


1-(4-Fluorobenzoyl)-9H-carbazole

Laube, M.; König, J.; Köckerling, M.; Knieß, T.

Abstract

1-(4-Fluorobenzoyl)-9H-carbazole (1) was synthesized starting from 9H carbazole and 4-fluorobenzonitrile by Friedel-Crafts acylation using boron trichloride to direct the substitu-tion in 1-position. Single X-ray crystal structure analysis unambiguously revealed the molecular structure of 1.

Keywords: Carbazole; Friedel-Crafts acylation; Boron trichloride; Structure determination

Involved research facilities

  • ZRT

Permalink: https://www.hzdr.de/publications/Publ-34863


Evaluation of prognostic factors after primary chemoradiotherapy of anal cancer: A multicenter study of the German Cancer Consortium- Radiation Oncology Group (DKTK-ROG)

Martin, D.; Schreckenbach, T.; Ziegler, P.; Filmann, N.; Kalinauskaite, G.; Tinhofer, I.; Budach, V.; Gani, C.; Zips, D.; Schimek-Jasch, T.; Schäfer, H.; Grosu, A. L.; Thomas, E.; Krause, M.; Dapper, H.; Combs, S.; Hoffmann, C.; Stuschke, M.; Walter, F.; Belka, C.; Kurth, I.; Hadiwikarta, W. W.; Baumann, M.; Rödel, C.; Fokas, E.

Abstract

Background and purpose: Prognosis after chemoradiotherapy (CRT) for anal squamous cell carcinoma
(ASCC) shows marked differences among patients according to TNM subgroups, however individualized
risk assessment tools to better stratify patients for treatment (de-) escalation or intensified follow-up are
lacking in ASCC.
Materials and methods: Patients’ data from eight sites of the German Cancer Consortium - Radiation
Oncology Group (DKTK-ROG), comprising a total of 605 patients with ASCC, treated with standard defini-
tive CRT with 5-FU/Mitomycin C or Capecitabine/Mitomycin C between 2004–2018, were used to evalu-
ate prognostic factors based on Cox regression models for disease-free survival (DFS). Evaluated variables
included age, gender, Karnofsky performance score (KPS), HIV-status, T-category, lymph node status and
laboratory parameters. Multivariate cox models were separately constructed for the whole cohort and
the subset of patients with early-stage (cT1-2 N0M0) tumors.
Results: After a median follow-up of 46 months, 3-year DFS for patients with early-stage ASCC was 84.9%,
and 67.1% for patients with locally-advanced disease (HR 2.4, p < 0.001). T-category (HR vs. T1: T2 2.02;
T3 2.11; T4 3.03), N-category (HR versus N0: 1.8 for N1-3), age (HR 1.02 per year), and KPS (HR 0.8 per
step) were significant predictors for DFS in multivariate analysis in the entire cohort. The model per-
formed with a C-index of 0.68. In cT1-2N0 patients, T-category (HR 2.14), HIV status (HR 2.57), age
(1.026 per year), KPS (HR 0.7 per step) and elevated platelets (HR 1.3 per 100/nl) were associated with
worse DFS (C-index of 0.7).
Conclusion: Classical clinicopathologic parameters like T-category, N-category, age and KPS remain to be
significant prognostic factors for DFS in patients treated with contemporary CRT for ASCC. HIV and plate-
lets were significantly associated with worse DFS in patients with early stage ASCC.

Keywords: Anal cancer; Chemoradiotherapy; Prognostic factors; Cox regression

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Permalink: https://www.hzdr.de/publications/Publ-34862


Influence of the First Wave of the COVID-19 Pandemic on Cancer Care in a German Comprehensive Cancer Center

Kirchberg, J.; Rentsch, A.; Klimova, A.; Vovk, V.; Hempel, S.; Folprecht, G.; Krause, M.; Plodeck, V.; Welsch, T.; Weitz, J.; Fritzmann, J.

Abstract

Introduction: During the first wave of the COVID-19 pandemic in 2020, the German
government implemented legal restrictions to avoid the overloading of intensive care units
by patients with COVID-19. The influence of these effects on diagnosis and treatment of
cancer in Germany is largely unknown.
Methods: To evaluate the effect of the first wave of the COVID-19 pandemic on tumor
board presentations in a high-volume tertiary referral center (the German Comprehensive
Cancer Center NCT/UCC Dresden), we compared the number of presentations of
gastrointestinal tumors stratified by tumor entity, tumor stage, and treatment intention
during the pandemic to the respective data from previous years.
Results: The number of presentations decreased by 3.2% (95% CI −8.8, 2.7) during the
COVID year 2020 compared with the pre-COVID year 2019. During the first shutdown,
March–May 2020, the total number of presentations was 9.4% (−18.7, 1) less than during
March–May 2019. This decrease was significant for curable cases of esophageal cancer
[N =37, 25.5% (−41.8, −4.4)] and colon cancer [N =36, 17.5% (−32.6, 1.1)] as well as
for all cases of biliary tract cancer [N =26, 50% (−69.9, −15)] during the first shutdown
from March 2020 to May 2020.
Conclusion: The impact of the COVID-19 pandemic on the presentation of oncological
patients in a CCC in Germany was considerable and should be taken into account when
making decisions regarding future pandemics.

Keywords: COVID-19 pandemic; cancer care; German health care; comprehensive cancer center

Permalink: https://www.hzdr.de/publications/Publ-34861


CRISPR-Cas9 Screen Identifies DYRK1A as a Target for Radiotherapy Sensitization in Pancreatic Cancer

Lan, B.; Zeng, S.; Zhang, S.; Ren, X.; Xing, Y.; Kutschick, I.; Pfeffer, S.; Frey, B.; Britzen-Laurent, N.; Grützmann, R.; Cordes, N.; Pilarsky, C.

Abstract

Although radiation therapy has recently made great advances in cancer treatment, the
majority of patients diagnosed with pancreatic cancer (PC) cannot achieve satisfactory outcomes
due to intrinsic and acquired radioresistance. Identifying the molecular mechanisms that impair
the efficacy of radiotherapy and targeting these pathways are essential to improve the radiation
response of PC patients. Our goal is to identify sensitive targets for pancreatic cancer radiotherapy
(RT) using the kinome-wide CRISPR-Cas9 loss-of-function screen and enhance the therapeutic
effect through the development and application of targeted inhibitors combined with radiotherapy.
We transduced pancreatic cancer cells with a protein kinase library; 2D and 3D library cells were
irradiated daily with a single dose of up to 2 Gy for 4 weeks for a total of 40 Gy using an X-ray
generator. Sufficient DNA was collected for next-generation deep sequencing to identify candidate
genes. In this study, we identified several cell cycle checkpoint kinases and DNA damage related
kinases in 2D- and 3D-cultivated cells, including DYRK1A, whose loss of function sensitizes cells
to radiotherapy. Additionally, we demonstrated that the harmine-targeted suppression of DYRK1A
used in conjunction with radiotherapy increases DNA double-strand breaks (DSBs) and impairs
homologous repair (HR), resulting in more cancer cell death. Our results support the use of CRISPR-
Cas9 screening to identify new therapeutic targets, develop radiosensitizers, and provide novel
strategies for overcoming the tolerance of pancreatic cancer to radiotherapy.

Keywords: pancreatic cancer; CRISPR-Cas9; radiotherapy; radioresistance; DYRK1A; Harmine; DNA damage repair; DNA double-strand break

Permalink: https://www.hzdr.de/publications/Publ-34860


Patterns Of Practice for Adaptive and Real-Time Particle Therapy (POP-ART PT), part II: Plan adaptation for interfractional changes

Trnkova, P.; Zhang, Y.; Toshito, T.; Heijmen, B.; Richter, C.; Aznar, M.; Bolsi, A.; Daartz, J.; Knopf, A.; Bertholet, J.

Abstract

Real-time respiratory motion management (RRMM, intra-fraction geometrical intervention) and Adaptive Particle Therapy (APT, inter-fraction adaptation of treatment plans) enable to account for anatomical variations and changes to optimize target coverage and organs-at-risk sparing. However, their current clinical implementation is unclear and expected to be highly heterogeneous. An institutional questionnaire, Patterns Of Practice for Adaptive and Real-Time Particle Therapy (POP-ART-PT), was distributed between 2021/01-06 to evaluate current clinical practice and wishes and barriers of the implementation. Here, we summarise the international survey results on APT for mitigation of interfractional anatomical changes from 70 particle therapy centers in 17 countries.

The response rate was 100% for Europe, 96% for Japan and 53% for USA. Of the 68 centers in operation, 84% (Figure1a) were APT users for at least one treatment site, with head and neck being the most common. APT was mostly performed offline (ad-hoc or per protocol) with only two users of online APT (plan library) and none using online daily replanning. Plan adaptation was in all cases motivated by both, target and OAR dose considerations (Figure1b). The most common imaging modality guiding APT was X-ray computed tomography. Sixty-eight percent of users plan to increase or change their APT technique. The greatest barriers to implementation were lack of integrated and efficient workflows and human resources (Figure2)

Offline APT has been widely implemented internationally, but online APT is still very rarely used. More research and development for integrated and efficient workflow is needed to facilitate the use of offline APT and enable online APT.

Involved research facilities

  • OncoRay
  • Lecture (Conference)
    PTCOG 60 - Jahreskonferenz der Particle Therapy Co-Operative Group, 28.06.-02.07.2022, Miami, USA

Permalink: https://www.hzdr.de/publications/Publ-34859


RawData - Liquid fraction investigations in a RPB (big printed zick-zack foam, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating printed zick-zack foam (big) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34858


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam 2, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Rotating Packed Bed; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34857


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam, zero point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Corneliusv

Abstract

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a zero point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34856


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34855


RawData - Liquid fraction investigations in a RPB (solid foam, single point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a single point injector. This repository contains

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34854


RawData - Liquid fraction investigations in a RPB (solid foam, 12 baffles) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a 12 baffle disc injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34853


RawData - Liquid fraction investigations in a RPB (solid foam, 32 baffles) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

Abstract

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a 32 baffle disc injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data. 

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34852


Liquid fraction investigations in a RPB with different foam and liquid inlet geometries using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.

Abstract

For liquid fraction investigations in a rotating packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected via different inlet geometries. This repository mainly contains the reconstructed CT data for the following configurations:

  • solid foam, 12 baffle liquid inlet
  • solid foam, 32 baffle liquid inlet
  • solid foam, single point liquid inlet
  • printed small zick-zack foam, multi point liquid inlet
  • printed small zick-zack foam, zero point liquid inlet
  • printed big zick-zack foam, multi point liquid inlet

Furthermore, the corresponding restructured sinogram raw data are included as well as diverse radiographic scans from different foam geometries that are used to arrange the RPB disc and the CT scanning plane as planar as possible and to define the vertically distributed scanning planes within the foams.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34851


Modeling COVID-19 Optimal Testing Strategies in Retirement Homes: An Optimization-based Probabilistic Approach

Davoodi Monfared, M.; Batista German, A. C.; Senapati, A.; Schlechte-Welnicz, W.; Calabrese, J.

Abstract

Retirement Home facilities have been widely affected by the COVID-19 pandemic. The residents in these homes are usually elderly people with a high risk of mortality from being infected. Since they are in contact with each other, once an infection arrives at the facility, it propagates quickly. To prevent the outbreaks, it has been demonstrated that regular testing of the residents is the most practical approach. However, testing may result in extra time for the staff that performs the test as well as residents' discontent, which presents a trade-off between the time invested in testing, daily caring activities, and viral spread containment. We introduce a novel optimization approach for testing schedule strategies in retirement homes. We develop a mixed-integer linear programming model for balancing the staff’s workload while minimizing the expected detection time of a probable infection inside the facility. We present a probabilistic approach in conjunction with the optimization models to compute the risk of infection, including contact rates, incidence status, and the probability of infection of the residents. To tackle the combinatorial nature of the problem, we proved an efficient property, called symmetry property of optimal testing strategy and utilized it in proposing an enhanced local search algorithm. We perform several experiments with real-size instances and show that the proposed approach can derive optimal testing strategies.

Keywords: Retirement Home; Testing Strategy; COVID-19

  • Open Access Logo Lecture (Conference)
    ESPOO 2022, 03.-06.07.2022, Helsinki, Finland

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Permalink: https://www.hzdr.de/publications/Publ-34850


Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks

Bollermann, T.; Yuan, T.; Kulenkampff, J.; Stumpf, T.; Fischer, C.

Abstract

Clay rock formations are considered as host rocks for underground radioactive waste repositories. Reliable predictions of diffusive transport heterogeneity are critical for assessing the sealing capacity of argillaceous rocks. The predictive power of numerical approaches to flow field analysis and radionuclide migration depends on the quality of the underlying pore network geometry. Both sedimentary and diagenetic complexity are controlling factors.
In this study, we demonstrate a cross-scale approach to reconstruct the pore network geometries of the sandy facies of the Opalinus Clay rock. We identified diagenetic and sedimentary subfacies components based on the concentration of diagenetic carbonates and sulfides and grain size variability, and quantified their pore size distributions and pore network geometries. A viable approach for use in transport modeling is to combine μ-CT data segmentation followed by filling the resulting volumes with representative pore network geometries based on FIB-SEM data. The resulting generalized pore network geometries are applied in digital rock models to calculate effective diffusivities, using a combined upscaling workflow for transport simulations from nanometer to micrometer scales.
Positron emission tomography (PET) diffusion experiments validated the transport simulation results. We introduced a statistical treatment of the PET and μ-CT tomographic datasets based on the spatial variability of both PET tracer concentrations and rock density. The analyzed effective diffusivities confirmed the numerical results.
This study illustrates three important steps in migration analysis: (i) a workflow of general applicability for cross-scale identification of pore network data in argillaceous rocks, (ii) application of the pore network data for the numerical analysis of diffusive transport, and (iii) validation of numerical results via combined PET - μ-CT diffusion experiments. Although the conceptual approach is not feasible for large numbers of samples, it opens up a strong potential for generalization: the validated results of effective diffusivities can now be easily used in a variety of segmented geometries. This allows to efficiently test upscaling concepts for the continuum scale on this basis.

Keywords: Diffusive transport; Transport modeling; Positron emission tomography (PET); Opalinus Clay; Radionuclide migration; Nuclear waste

Permalink: https://www.hzdr.de/publications/Publ-34849


Chemical flowers: Buoyancy-driven instabilities under modulated gravity during a parabolic flight

Stergiou, Y.; Hauser, M. J. B.; Wit, A. D.; Schuszter, G.; Horvath, D.; Eckert, K.; Schwarzenberger, K.

Abstract

This paper is associated with a video winner of the 2021 American Physical Society’s Division of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2021.GFM.V0036.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-34848


Viscous fingering in a non-Newtonian liquid radial displacement by surfactant (C14TAB)-polymer (Xanthnan Gum) interaction

Stergiou, Y.; Perrakis, A.; Keshavarzi, B.; Javadi, A.; Eckert, K.; Schwarzenberger, K.

Abstract

We investigated a miscible displacement of a less viscous liquid by a more viscous shear-thinning liquid in a Hele-Shaw cell. Due to a coacervation
reaction between both liquids, a hydrodynamic instability appears in the form of inward viscous fingering. The liquids consisted of a solution of
the anionic biopolymer xanthan gum, as the injection liquid, which displaced a cationic surfactant (C14TAB) aqueous solution (Keshavarzi et al.,
2019). In the contact zone between the two solutions, the oppositely charged species form polymer-surfactant complexes due to electrostatic
interactions. The electrostatic and hydrophobic interactions between these complexes lead to a self-assembly process, forming a membrane
structure separated from the main solution. During the continuing radial displacement, a large variety of patterns can emerge which is attributed
to the rheological properties of the system involving viscosity gradients, the non-Newtonian nature of the displacing solution and the complex
rheology of the coacervate phase. Variation of the flow rate and gap width of the Hele-Shaw cell revealed distinct instability regimes and allowed
to identify main contributing mechanisms. These insights open the door for further investigation of fluid mechanics problems (i.e. Saffman-Taylor
instability) (Saffman & Taylor, 1958) in multiphase systems of complex rheology and its applications in engineering and technology.
References:
Keshavarzi, B., Langmuir. 2019, 35(42), 13624-13635.
Saffman, P., & Taylor, G. Proceedings of the Royal Society A: Mathematical, Physical. 1958, 245(1242), 312-329.
Acknowledgements: This work was supported by the German Aerospace Center (DLR) with funds provided by the Federal Ministry for
Economic Affairs and Energy (BMWi), Grant No. 50WM2061 (project ChemFront).

  • Lecture (Conference)
    Annual European Rheology Conference (AERC 2022), 26.-28.04.2022, Sevilla, Spain

Permalink: https://www.hzdr.de/publications/Publ-34847


Physics-Informed and Data-Driven Molecular Dynamics Simulations of Iron under Extreme Conditions

Ramakrishna, K.; Lokamani, M.; Nikolov, S.; Tranchida, J.; Wood, M.; Cangi, A.

Abstract

We present a new Spectral Neighbor Analysis Potential (SNAP) machine-learning potential for large-scale molecular dynamics simulations of Iron. SNAP is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. The development of the SNAP potential entails three steps: (1) the creation of a training database comprised of a consistent and meaningful set of first-principles Density Functional Theory (DFT) data for Iron at a range of high pressures (0-400 GPa) and temperatures (0-6500 K); (2) the robust and physically guided training of the SNAP hyper-parameters based on DFT data using statistical data analysis; and (3) the validation of the SNAP potential in molecular dynamics simulations of Iron by evaluating transport properties at extreme conditions up to those prevalent in Earth's core.

Keywords: Warm dense matter; Matter under extreme conditions; Computational Physics

  • Poster
    Young Researcher's Workshop on Machine Learning for Materials 2022, 09.-13.05.2022, Trieste, Italy

Permalink: https://www.hzdr.de/publications/Publ-34846


Maskless magnetic patterning using cobalt and dysprosium focused ion beams

Lenz, K.; Pablo Navarro, J.; Klingner, N.; Hlawacek, G.; Samad, F.; Narkovic, R.; Hübner, R.; Pilz, W.; Meyer, F.; Mazarov, P.; Bischoff, L.; Lindner, J.

Abstract

We present results for direct maskless magnetic patterning of ferromagnetic nanostructures using a special liquid metal alloy ion source for focused ion beam (FIB) systems. We used a Co36Nd64 alloy as the FIB source [1]. A Wien mass filter allows for quick switching between the ion species in the alloy without changing the FIB source. A 5000×1000×50 nm3 permalloy strip served as the sample. Using the FIB we implanted a 300-nm-wide track with Co ions (see Fig.1). We observed the Co-induced changes by measuring the sample with microresonator ferromagnetic resonance before and after the implantation. Structures as small as 30 nm can be implanted up to a concentration of 10 % near the surface. Such lateral resolution is hard to reach for other lithographic methods. This allows for easy magnetic modification of edge-localized spin waves.
In another set of samples, we implanted Dy ions to locally increase the damping in a stripe pattern of ~120-nm-wide strips with 400 nm periodicity on a total area of 1×1 mm². Thus, the Gilbert damping parameter can be easily increased by one order of magnitude with a lateral resolution of about 100 nm.
In contrast to electron beam lithography in combination with broad-beam ion implantation, the maskless FIB process does not require the cumbersome and difficult removal of the ion-hardened resist if optical measurements like BLS or TR-MOKE are needed.

Keywords: ferromagnetic resonance; focused ion beams; nanostructures; implantation

Involved research facilities

Related publications

  • Poster
    Magnonics 2022, 31.07.-04.08.2022, Oxnard, USA
  • Lecture (Conference)
    DPG-Tagung der Sektion Kondensierte Materie (SKM), 04.-09.09.2022, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34845


Nonstationary spin waves under a uniform excitation in a confined permalloy microstrip directly imaged with STXM-FMR

Pile, S.; Stienen, S.; Lenz, K.; Narkovic, R.; Wintz, S.; Förster, J.; Mayr, S.; Buchner, M.; Weigand, M.; Ney, V.; Lindner, J.; Ney, A.

Abstract

Spin waves are one of the options to replace the transfer of electronic charges in logic devices to make information processing faster and more efficient [1]. A fundamental understanding of the dynamic magnetic properties of confined rectangular strips is a prerequisite for the development of nanoscale computational devices. Planar microresonators/microantennas made it possible not only to measure spin wave dynamics in a single microstrip, but to apply synchrotron-based time-resolved scanning transmission microscopy (TR-STXM) [3] using a phase-locked ferromagnetic resonance (FMR) excitation scheme (STXM-FMR). STXM-FMR enables direct temporally resolved imaging of the spatial distribution of the precessing magnetization within the microstrip during FMR excitation with elemental selectivity. FMR modes in a single rectangular permalloy microstrip were directly imaged using STXM-FMR and the findings were corroborated by micromagnetic simulations showing a very good agreement [5]. Under uniform excitation in a single confined microstrip typically standing spin waves are expected, nevertheless all imaged spin waves are nonstationary at and off resonance.

Keywords: ferromagnetic resonance; x-ray transmission microscopy; nanostructures

  • Invited lecture (Conferences)
    NESY User Symposium 2022, 29.-30.09.2022, Leoben, Österreich
  • Poster
    7. Conference on Magnonics 2022, 31.07.-04.08.2022, Oxnard, USA

Permalink: https://www.hzdr.de/publications/Publ-34844


Synthesis of novel PSMA ligands and preclinical evaluation of [99mTc]TcO-ABX474, a radioligand for SPECT imaging of prostate cancer

Ludwig, F.-A.; Lis, C.; Ullrich, M.; Lankau, H.-J.; Sihver, W.; Joseph, D.; Eiselt, E.; Meyer, C.; Gündel, D.; Deuther-Conrad, W.; Brust, P.; Donat, C. K.; Bachmann, M.; Pietzsch, H.-J.; Pietzsch, J.; Fischer, S.; Kopka, K.; Hoepping, A.

Abstract

Objectives: During the last 15 years several PSMA PET ligands for prostate cancer imaging have been developed resulting in the recent approvals of 68Ga-PSMA-11, 18F-PSMA-1007 and 18F-DCFPyL.[1,2] However, 99mTc remains a popular radiometal for SPECT imaging due to its longer half-life and availability from 99Mo/99mTc generators especially in outpatient imaging centers. Due to the widespread availability of SPECT cameras PSMA SPECT ligands have the potential to substantially extend the availability of PSMA-based imaging, but currently no PSMA SPECT ligand is approved. MIP-1404, PSMA-I&S and HYNIC-iPSMA are rare examples of PSMA SPECT tracers in clinical development. Accordingly, the aim of our study was to develop a PSMA ligand for 99mTc SPECT imaging of prostate cancer based on an N2S2 chelator, which enables reliable radiolabeling to form stable 99mTc complexes.[3]

Methods: A number of compounds, which contain the PSMA binding motif Glu-urea-Lys, a varying linker and a bisaminothiol (BAT)-type N2S2 chelator, were synthesized. Selected compounds were radiolabeled with 99mTc, followed by assessment of in vitro stability of the formed complexes via radio-HPLC. The specific binding affinity towards PSMA and the internalization of the radioligands were examined in LNCaP cells, supplemented by autoradiographic studies. Tissue distribution and tumor accumulation were evaluated in LNCaP-tumor bearing mice via quantitative SPECT/CT imaging, benchmarked with [99mTc]Tc-PSMA-I&S[4] and [68Ga]Ga-PSMA-11.

Results: Among the six 99mTc radioligands synthesized and examined, [99mTc]TcO-ABX474 showed most favorable properties. Radiolabeling of ABX474 (50 µg) was achieved starting from [99mTc]NaTcO4 (0.2-2 GBq) in saline (1.4 mL) using SnCl2 (1 µg in 0.01 M HCl) as reducing agent, in presence of calcium-D-heptagluconate (10 µg) and D-mannitol (1 mg) at pH 5-6. Incubation at r.t. for 20 min followed by heating at 80°C for 20 min afforded the product-containing solution with a radiochemical purity of 93.8 ± 3.1 % (n=20) optimization planned during kit development). [99mTc]TcO-ABX474 was stable in DPBS (96.7 ± 2.1 % unchanged, n=3) at 25°C for 20 h as well as in mouse plasma (96.7 ± 1.3 % unchanged, n=3) and human plasma (91.7 ± 0.3 % unchanged, n=5) at 37°C for 6 h, respectively. [99mTc]TcO-ABX474 showed high binding affinity towards PSMA (Kd= 7.2 ± 1.7 nM) and substantial uptake in LNCaP cells (binding: 3.2 %AD/mg protein internalization: 2.8 %AD/mg protein, 47% internalization of total cell bound activity at 37°C).
In LNCaP xenograft mice, [99mTc]TcO-ABX474 showed high PSMA-specific tumor uptake, mainly renal excretion and moderate kidney retention. Hence, [99mTc]TcO-ABX474 exhibited higher tumor-to-background ratios (SUV) between 1‒4 hours after injection (tumor/muscle: 25.2‒52.7 tumor/kidney: 0.3‒0.37) compared to the reference compound [99mTc]Tc-PSMA-I&S (tumor/muscle: 5.7‒18.2 tumor/kidney: 0.17‒0.2). [99mTc]TcO-ABX474 allowed for similar tumor visualization compared to PET/CT imaging with [68Ga]Ga-PSMA-11 (tumor/muscle: 22.9 tumor/kidney: 0.24) 1 hour after injection.

Conclusion: This study demonstrates that [99mTc]TcO-ABX474 is a promising radiotracer candidate for PSMA-specific SPECT imaging of prostate cancer warranting further clinical evaluation.

Acknowledgments: The authors would like to thank the Sächsische Aufbaubank - Förderbank - for financial support (100363946).

References:

[1] https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-second-psma-targeted-pet-imaging-drug-men-prostate-cancer, published on 27/05/2021.

[2] https://www.has-sante.fr/jcms/p_3337433/en/radelumin-18f-psma-1007-cancer-de-la-prostate, published on 04/05/2022.

[3] Hoepping, A. et al., EPO Patent Application EP22174909.6, 23/05/2022.

[4] Robu, S. et al., J Nucl Med 2017, 58, 235-242.

  • Lecture (Conference)
    TERACHEM 2022: The Fourth International Symposium on Technetium and Other Radiometals in Chemistry and Medicine, 14.-17.09.2022, Bressanone (Brixen), Italien
    DOI: 10.1016/S0969-8051(22)02136-9
  • Abstract in refereed journal
    Nuclear Medicine and Biology 114-115(2022), S19
    DOI: 10.1016/S0969-8051(22)02136-9

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-34843


CMOS-compatible manufacturability of sub-15 nm Si/SiO2/Si nanopillars containing single Si nanodots for single electron transistor applications

Borany, J.; Engelmann, H.-J.; Heinig, K.-H.; Amat, E.; Hlawacek, G.; Klüpfel, F.; Hübner, R.; Möller, W.; Pourteau, M.-L.; Rademaker, G.; Rommel, M.; Baier, L.; Pichler, P.; Perez-Murano, F.; Tiron, R.

Abstract

This study addresses the complementary metal-oxide-semiconductor-compatible fabrication of vertically stacked Si/SiO2/Si nanopillars (NPs) with embedded Si nanodots (NDs) as key functional elements of a quantum-dot-based, gate-all-around single-electron transistor (SET) operating at room temperature. The main geometrical parameters of the NPs and NDs were deduced from SET device simulations using the nextnano++ program package. The basic concept for single silicon ND formation within a confined oxide volume was deduced from Monte-Carlo simulations of ion-beam mixing and SiOx phase separation. A process flow was developed and experimentally implemented by combining bottom-up (Si ND self-assembly) and top-down (ion-beam mixing, electron-beam lithography, reactive ion etching) technologies, fully satisfying process requirements of future 3D device architectures. The theoretically predicted self-assembly of a single Si ND via phase separation within a confined SiOx disc of < 500 nm³ volume was experimentally validated. This work describes in detail the optimization of conditions required for NP/ND formation, such as the oxide thickness, energy and fluence of ion-beam mixing, thermal budget for phase separation and parameters of reactive ion beam etching. Low-temperature plasma oxidation was used to further reduce NP diameter and for gate oxide fabrication whilst preserving the pre-existing NDs. The influence of critical dimension variability on the SET functionality and options to reduce such deviations are discussed. We finally demonstrate the reliable formation of Si quantum dots with diameters of less than 3 nm in the oxide layer of a stacked Si/SiO2/Si NP of 10 nm diameter, with tunnelling distances of about 1 nm between the Si ND and the neighboured Si regions forming drain and source of the SET.

Keywords: CMOS; single-electron transistor; nanostructure fabrication; nanpillars; silicon nanodot; self-organization; ion-beam mixing

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-34842


PET Imaging of Cholinergic Neurotransmission in Neurodegenerative Disorders

Tiepolt, S.; Meyer, P. M.; Patt, M.; Deuther-Conrad, W.; Hesse, S.; Barthel, H.; Sabri, O.

Abstract

As a neuromodulator, the neurotransmitter acetylcholine plays an important role in cognitive, mood, locomotor, sleep/wake, and olfactory functions. In the pathophysiology of
most neurodegenerative diseases, such as Alzheimer disease (AD) or Lewy body disorder (LBD), cholinergic receptors, transporters, or enzymes are involved and relevant as
imaging targets. The aim of this review is to summarize current knowledge on PET imaging of cholinergic neurotransmission in neurodegenerative diseases. For PET imaging
of presynaptic vesicular acetylcholine transporters (VAChT), (-)-18F-fluoroethoxybenzovesamicol (18F-FEOBV) was the first PET ligand that could be successfully translated
to clinical application. Since then, the number of 18F-FEOBV PET investigations on patients with AD or LBD has grown rapidly and provided novel, important findings
concerning the pathophysiology of AD and LBD. Regarding the α4β2 nicotinic acetylcholine receptors (nAChRs), various second-generation PET ligands, such as 18F-nifene,
18F-AZAN, 18F-XTRA, (-)-18F-flubatine, and (+)-18F-flubatine, were developed and successfully translated to human application. In neurodegenerative diseases such as AD
and LBD, PET imaging of α4β2 nAChRs is of special value for monitoring disease progression and drugs directed to α4β2 nAChRs. For PET of α7 nAChR, 18F-ASEM and
11C-MeQAA were successfully applied in mild cognitive impairment and AD, respectively. The highest potential for α7 nAChR PET is seen in staging, in evaluating disease
progression, and in therapy monitoring. PET of selective muscarinic acetylcholine receptors (mAChRs) is still in an early stage, as the development of subtype-selective
radioligands is complicated. Promising radioligands to image mAChR subtypes M1 (11C-LSN3172176), M2 (18F-FP-TZTP), and M4 (11C-MK-6884) were developed and
successfully translated to humans. PET imaging of mAChRs is relevant for the assessment and monitoring of therapies in AD and LBD. PET of acetylcholine esterase activity
has been investigated since the 1990s. Many PET studies with 11C-PMP and 11C-MP4A demonstrated cortical cholinergic dysfunction in dementia associated with AD and
LBD. Recent studies indicated a solid relationship between subcortical and cortical cholinergic dysfunction and noncognitive dysfunctions such as balance and gait in LBD.
Taken together, PET of distinct components of cholinergic neurotransmission is of great interest for diagnosis, disease monitoring, and therapy monitoring and to gain insight
into the pathophysiology of different neurodegenerative disorders.

Keywords: acetylcholine; Alzheimer disease; Lewy body disorder; neurodegenerative disorde; neurology; PET

Permalink: https://www.hzdr.de/publications/Publ-34841


Assessment of the flow modulation technique for measuring axial liquid dispersion coefficients in trickle-bed reactors

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

Abstract

This study proposes a novel non-intrusive approach for measuring axial liquid dispersion coefficients in trickle-bed reactors. The approach is based on the flow modulation technique (FMT), which replaces traditional tracer substance injections with a marginal sinusoidal modulation superimposed on the liquid inlet flow. The modulation causes a sinusoidal variation of the liquid holdup in time, i.e. liquid holdup wave. Downstream the inlet, the holdup wave gets damped in amplitude and shifted in phase due to dispersion. Amplitude damping and phase shift are experimentally measured and related to the value of the axial dispersion coefficient using a one-dimensional dispersion model. Recently, the flow modulation has been applied to investigate the axial gas dispersion coefficient in bubble columns. In this study, the approach is adapted to measure liquid dispersion in co-current gas-liquid trickle-bed reactors. In addition, the consequences of the assumptions requested by the axial dispersion model are discussed. Furthermore, the impact of the experimental flow modulation parameters on sensitivity and uncertainty of the dispersion coefficient is analyzed.

Keywords: liquid flow modulation; axial liquid dispersion coefficient; trickle-bed reactors

  • Contribution to proceedings
    15th International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering (GLS-15), 07.-10.08.2022, Ottawa, Canada
    Assessment of the flow modulation technique for measuring axial liquid dispersion coefficients in trickle-bed reactors

Permalink: https://www.hzdr.de/publications/Publ-34840


Air-stripping of isobutyl acetate in aqueous solution for measuring tray and point efficiencies in hydraulic air/water column mockups

Marchini, S.; Vishwakarma, V.; Schubert, M.; Brunazzi, E.; Hampel, U.

Abstract

The knowledge of the tray efficiency value is crucial for a correct design of tray columns [1]. In the last decades, several models have been developed for predicting the tray efficiency value, given the point efficiency. Validation of these models requires determining both tray and point efficiency experimentally.
The tray efficiencies are mostly determined by sampling the incoming and exiting streams of liquid and gas over the tray. On the contrary, experimentally determining point efficiencies is technically challenging and thus, their value is often derived from correlations or small-scale experiments (e.g. Oldershaw columns). Only few studies on the experimental determination of point efficiencies on large-scale distillation trays exist (e.g. [2], [3]). The physical systems used in these studies pose several technical restrictions and safety concerns. For these reasons, a setup designed ad hoc for point efficiency studies is mostly needed.
Recently Marchini et al. [4] proposed the stripping of isobutyl acetate from an aqueous solution using air as a physical system,which was proven to offer several advantages over the traditional ones and to be readily integrated into existing cold fluid air/water mockups without any major modification. The authors also showed how the tray-to-point efficiency ratio can be determined based on the liquid concentration distribution on the tray, accounting for liquid mixing phenomena in both the axial and transversal directions.
In this study, the tray and point efficiency values of an 800 mm dia. distillation sieve tray were determined at different gas and liquid flow rates by sampling the liquid at different deck locations for subsequent UV-spectroscopy, obtaining the liquid concentration distribution (Figure 1).

Keywords: distillation tray; tray efficiency; weeping

  • Contribution to proceedings
    Distillation and Absorption 2022, 18.-21.09.2022, Toulouse, France
    Proceedings of Distillation and Absorption 2022

Permalink: https://www.hzdr.de/publications/Publ-34839


Np(V) sorption onto zirconia: a combined spectroscopy, batch and modeling study

Jessat, I.; Roßberg, A.; Scheinost, A.; Lützenkirchen, J.; Foerstendorf, H.; Stumpf, T.; Jordan, N.

Abstract

When assessing the long-term safety of a nuclear waste repository, the interactions of dissolved long-lived radionuclides, such as the actinide neptunium, with corroded phases in the near-field of the repository have to be considered. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of nuclear fuel rods and can constitute a first barrier against the release of mobilized radionuclides into the environment.
To gain a detailed understanding of the Np(V) sorption processes at the zirconia‒water interface, a comprehensive multimethod approach was pursued. Molecular level information about the Np(V) surface species were derived by in situ Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). The Np L₃-absorption edge (17,610 eV) is commonly used for EXAFS investigations of neptunium. However, the Zr K absorption edge (17,998 eV) is close in energy to the Np L₃-edge, reducing the k-range that can be evaluated. Since attempts to use the Np L₂-edge (21,600 eV) with an energy above the Zr K-edge were not successful, the Np L₃-edge EXAFS spectra had to be used to gain information about the molecular environment of the sorbed Np(V) surface species. The short Np-Zr distance of approximately 3.6 Å derived from EXAFS spectra revealed the predominant formation of bidentate inner-sphere Np(V) surface complexes. ATR FT-IR experiments were conducted at different pH values and a shift of the asymmetric stretching vibration of Np(V) (𝜈₃(NpO₂⁺) towards lower energies was observed at acidic pH, revealing the interactions between Np(V) and ZrO₂. Furthermore, the sorption process was only slightly reversible, also indicating the formation of Np(V) inner-sphere complexes. However, with increasing pH, vibrational surface modes of the ZrO₂ matrix appeared, which were overlapping with Np(V) stretching frequency and impeding the investigation of the pH-dependent surface speciation of Np(V).
Batch sorption experiments (varying ionic strength, Np(V) concentration, and solid-to-liquid ratio (m/V)) as well as a sorption isotherm experiment at pH 6 were conducted to study the sorption processes of the Np(V)‒ZrO₂ system on the macroscopic scale. The sorption of Np(V) was independent of ionic strength, also indicating the formation of Np(V) inner-sphere surface complexes. This was supported by zeta potential measurements in the presence of neptunium, where a shift to higher pH values of the isoelectric point of the neat ZrO₂ was observed. With increasing m/V the Np(V) sorption edge was shifted towards lower pH values, indicating the presence of different kinds of sorption sites, which was also deduced from the shape of the sorption isotherm.
Reliable information about the number and denticity of surface species obtained by spectroscopic and macroscopic investigations enable modeling approaches such as surface complexation modeling (SCM) to be robust. The results derived by SCM will in turn contribute to a more reliable prediction of the environmental fate of neptunium.

Keywords: neptunium(V); zirconia; ZrO₂; spectroscopy; EXAFS; IR; sorption

Involved research facilities

Related publications

  • Lecture (Conference)
    ATAS-AnXAS 2022 5th International Workshop on Advanced Techniques in Actinide Spectroscopy 9th Workshop on Speciation, Techniques and Facilities for Synchrotron Radiation, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34837


Spectroscopic investigations of the U(VI) sorption onto the zircaloy corrosion product ZrO2

Jessat, I.; Foerstendorf, H.; Heim, K.; Roßberg, A.; Scheinost, A.; Stumpf, T.; Jordan, N.

Abstract

For a safety assessment of a repository for nuclear waste, the interactions of actinides with corroded phases in the near-field must be taken into account. Most commercial fission reactors use uranium-based fuels and the spent nuclear fuel still contains approximately 95 % of uranium, making it the largest fraction of the spent nuclear fuel by mass. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of nuclear fuel rods and can act as a first barrier against the release of mobilized radionuclides from the spent nuclear fuel into the environment. Furthermore, the complexation of dissolved radionuclides with common inorganic ligands, such as carbonate, in the groundwater can have a significant influence on the formation and structure of actinide surface species and thus their mobility in the environment.
In situ Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) were applied to investigate the U(VI) speciation at the ZrO₂-water interface. A pH-dependent speciation of U(VI) at the zirconia surface could be observed under inert gas conditions with EXAFS and the preliminary results indicated the presence of two inner-sphere U(VI) surface species with different structural environments. The EXAFS results can be compared to the literature results of Lomenech et al., where also two U(VI) surface species on the ZrO₂ surface were observed (a tridentate U(VI) surface species at pH 3 and a bidentate surface species at higher pH) [1,2].
The sorption of U(VI) onto ZrO₂ under inert gas conditions was also studied with ATR FT-IR at pH 3.5 and 5.5 and a pH-dependent U(VI) speciation was observed, supporting the findings from the EXAFS investigations. The observed red shift of the asymmetric stretching vibration of the free uranyl aqua ion (𝜈₃(UO₂²⁺)) in the presence of ZrO₂ at pH 5.5 was due to the U(VI)‒ZrO₂ interactions. At a lower pH of 3.5 a second U(VI) surface species with a less pronounced red shift of the ν₃ vibration was identified.
A pH-dependence of the sorption of atmospheric carbonate on the zirconia surface was observed and a spectral splitting (Δ𝜈) of approximately 200 cm⁻¹ of the symmetric and asymmetric stretching vibration modes indicated the presence of bidentate bound carbonate species on the surface. The U(VI) sorption onto zirconia pre-equilibrated with atmospheric carbonate was also studied at pH 5.5 and 3.5. Compared to the experiments conducted under inert gas conditions, the red shift of the ν₃ mode of U(VI) at pH 5.5 was more pronounced in the presence of carbonate, indicating an influence of carbonate on the formed U(VI) surface species. In addition, changes in the frequency of the asymmetric and symmetric stretching vibrations of carbonate sorbed to the zirconia surface were observed in the presence of U(VI), also hinting towards structural changes in the surface species.
EXAFS and ATR FT-IR investigations provided valuable structural information about the formed U(VI) sorption species on the ZrO₂ surface in the presence and absence of carbonate. The improved molecular level understanding of such sorption processes will enable more reliable predictions of the environmental fate of U(VI). Such results will be complemented with batch sorption experiments as well as thermodynamic surface complexation modeling.

[1] Lomenech, C. et al. (2003) Radiochim. Acta 91(8), 453-461.
[2] Lomenech, C. et al. (2003) J. Colloid Interface Sci. 261(2), 221-232.

Keywords: uranium(VI); zirconia; ZrO₂; spectroscopy; IR; EXAFS; carbonate; sorption

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  • Poster
    ATAS-AnXAS 2022 5th International Workshop on Advanced Techniques in Actinide Spectroscopy 9th Workshop on Speciation, Techniques and Facilities for Synchrotron Radiation, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34836


Magnetically Sensitive Electronic Skins for Supervised Folding of Origami Actuators

Oliveros Mata, E. S.; Makushko, P.; Ha, M.; Canon Bermudez, G. S.; Liu, J. A.-C.; Evans, B. A.; Tracy, J. B.; Makarov, D.

Abstract

Soft actuators are required to deform, fold, or unfold in order to interact with their surroundings.[1] One strategy to achieve the movement of mechanically soft systems is the use of magnetic fields for untethered actuation. Flexible magnetic composites have been demonstrated as functional grippers, rollers, and walkers upon applied external magnetic fields.[2] Being controlled with electromagnetic coils, magnetic actuators can profit from high-speed actuation to quickly respond to their environment.[3]

The development of an appropriate sensory tracking system for soft actuators is a research topic with open challenges. Light, conformal, and mechanically imperceptible sensing systems are to be developed to be compatible with soft actuators. In this work, we present flexible magnetosensitive electronic skin which relies on thin-film magnetic field sensors to enable onboard folding control of origami-like soft actuators. The flexible electronic skin consists of thin film giant magnetoresistive GMR and Hall effect sensors that are used to measure the magnetization state of the actuator, the applied magnetic fields, and the completeness of the bending process. The resulting intelligent material is mechanically designed to fold even when the flexible magnetic skin is attached to the soft actuator.[4]

The magnetic origami actuators are made of thin DiAPLEX foils, a shape memory polymer, with embedded NdFeB particles. Such composite can be used to achieve magnetically induced motion using magnetic fields and a directed light source to increase locally the temperature. We experimentally found the best thickness (60 µm) and concentration (40 NdFeB wt%) parameters to achieve magnetic folds.[4]

The integration of magnetic soft actuators with e-skins allowed self-guided assembly of the origami foils. We showed two case studies showing that this approach is useful for assembling boxes and boat-like origami shapes. This integration process was monitored, followed, and controlled by the output of the laminated sensors. [4]

[1] A. Miriyev, et al. Nat. Commun. 8, 596 (2017)

[2] S. Wu, et al. Multifunct. Mater. 3, 042003 (2020)

[3] X. Wang, et al. Commun. Matter. 1, 67 (2020)

[4] M. Ha, et al. *Adv. Mater. 33, 2008751 (2021)

  • Lecture (Conference)
    67th Annual Conference on Magnetism and Magnetic Materials (MMM 2022), 31.10.-04.11.2022, Minneapolis, United States

Permalink: https://www.hzdr.de/publications/Publ-34835


Detecting Magnetic Fields with Printed Magnetoresistive Sensors on Rigid and Flexible Substrates

Oliveros Mata, E. S.; Voigt, C.; Makushko, P.; Xu, R.; Ha, M.; Canon Bermudez, G. S.; Kosub, T.; Mönch, J. I.; Zabila, Y.; Illing, R.; Wang, Y.; Valdez-Garduño, N. M.; Fritsch, M.; Mosch, S.; Kusnezoff, M.; Faßbender, J.; Vinnichenko, M.; Makarov, D.

Abstract

The development of functional printable materials enables the production of electronic components in unconventional materials and different form factors[1]. Here, we show magnetically sensitive inks/pastes based on magnetoresistive powder that can be printed via stencil, dispenser, or screen printing. We employ bismuth microparticles[2] as well as [Co/Cu], [Py/Cu],[3] and permalloy [4] flakes showing giant, anisotropic, or non-saturating large magnetoresistance, respectively.

We demonstrate that magnetic field sensors based on various types of magnetoresistive flakes can be printed onto rigid, flexible, and deformable substrates. We employed block-copolymers and elastic binders to enable mechanical resilience of these sensors: they can withstand bending down to 16 µm, 100% of stretching, and bending for hundreds of cycles without losing functionality.[3]

Additionally, by automatizing the dispenser printing process of bismuth-based pastes, we demonstrate the production of fully printed magnetic field sensors. The use of a micro-optically optimized high-power diode laser array provided a versatile approach for selective sintering of sensors over flexible foils in areas exceeding several square centimeters. In this work we experimentally confirm that such sensors retain their non-saturating magnetoresistive performance (MR = 146%) in high field conditions, allowing operation above 5 T. [2]

Our printed magnetic field sensors can be used to create interfaces that are responsive to magnetic fields through remote human input. Being flexible, they can be laminated on the skin, or stuck onto any object, from a desk to a house wall. We demonstrate the capabilities of printed magnetic field sensors to work as an interface to navigate through digital maps, as input panels for smart home applications, and as interactive wallpapers.

[1] A. Kamyshny, et al. 1905279 (2020) *Chem. Soc. Rev.* **48**, 1712 (2019)

[2] E.S. Oliveros-Mata, et al. *Appl. Phys. A* **127,** 280 (2021)

[3] M. Ha, et al. *Adv. Mater.* **33,** 2005521 (2021)

[4] E.S. Oliveros‐Mata, E. S., C. Voigt, et al. *Adv. Mater. Technol.* 2200227 (2022)

  • Lecture (Conference)
    67th Annual Conference on Magnetism and Magnetic Materials (MMM 2022), 31.10.-04.11.2022, Minneapolis, United States

Permalink: https://www.hzdr.de/publications/Publ-34834


New analytical tools for studying habitat selection in terrestrial mammals

Alston, J.; Fleming, C. H.; Calabrese, J.

Abstract

The study of habitat selection is a foundational component of basic and applied animal ecology. Today, habitat selection in mammals is primarily studied using resource selection functions, a class of models that uses logistic regression to compare “used” to “available” habitat. However, these models have several statistical problems, including rampant pseudoreplication from failing to account for autocorrelation in modern animal movement data, no clear guidelines for sampling available habitat, and large amounts of numerical error from sampling too few available points. These problems are widely acknowledged but have no generally accepted solutions, so we propose three new methods for addressing them: likelihood weighting, Gaussian availability sampling, and numerical convergence checks. We demonstrate the practical advantages of these methods over conventional approaches using simulations and empirical data on a water mongoose (Atilax paludinosus), a caracal (Caracal caracal), and a serval (Leptailurus serval), and briefly demonstrate how to apply our methods to animal tracking data using the ‘ctmm’ R package. Broad uptake of these methods could substantially improve our estimates of habitat selection in mammals.

  • Lecture (Conference)
    American Society of Mammalogists Annual Meeting, 16.-21.06.2022, Tucson, AZ, USA

Permalink: https://www.hzdr.de/publications/Publ-34830


MRI magnitude signal-based proton beam visualisation in water phantoms reflects composite effects of beam-induced buoyant convection and radiation chemistry

Schieferecke, J.; Gantz, S.; Karsch, L.; Pawelke, J.; Hoffmann, A. L.

Abstract

Objective. Local magnetic resonance (MR) signal loss was previously observed during proton beam
irradiation of free-floating water phantoms at ambient temperature using a research prototype in-
beam magnetic resonance imaging (MRI) scanner. The emergence of this MR signal loss was
hypothesised to be dependent on beam-induced convection. The aim of this study was therefore to
unravel whether physical conditions allowing the development of convection must prevail for the
beam-induced MRI signatures to emerge. Approach. The convection dependence of MRI magnitude
signal-based proton beam visualisation was investigated in combined irradiation and imaging
experiments using a gradient echo (GE)-based time-of-flight (ToF) angiography pulse sequence,
which was first tested for its suitability for proton beam visualisation in free-floating water phantoms
at ambient temperature. Subsequently, buoyant convection was selectively suppressed in water
phantoms using either mechanical barriers or temperature control of water expansivity. The
underlying contrast mechanism was further assessed using sagittal imaging and variation of T1
relaxation time-weighting. Main results. In the absence of convection-driven water flow, weak beam-
induced MR signal changes occurred, whereas strong changes did occur when convection was not
mechanically or thermally inhibited. Moreover, the degree of signal loss was found to change with the
variation of T1-weighting. Consequently, beam-induced MR signal loss in free-floating water
phantoms at ambient temperature does not exclusively originate from buoyant convection, but is
caused by local composite effects of beam-induced motion and radiation chemistry resulting in a local
change in the water T1 relaxation time. Significance. The identification of ToF angiography sequence-
based proton beam visualisation in water phantoms to result from composite effects of beam-induced
motion and radiation chemistry represents the starting point for the future elucidation of the currently
unexplained motion-based MRI contrast mechanism and the identification of the proton beam-
induced material change causing T1 relaxation time lengthening.

Keywords: magnetic resonance imaging; MRI; in-beam MRI; proton therapy; proton beam visualisation; convection; oxygen depletion

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Permalink: https://www.hzdr.de/publications/Publ-34828


Transferability of DFT surrogate models: Temperature and system size

Fiedler, L.; Cangi, A.

Abstract

While Density Functional Theory (DFT) is the most common tool for the investigation of materials under extreme conditions, its scaling behavior with respect to both system size and temperature makes large scale simulations challenging. Yet, progress in this regard would enable accurate modeling of planetary interiors or radiation damage in fusion reactor walls.
One possible route to alleviate these scaling problems is through the use of surrogate models, i.e., machine-learning models. These are trained on DFT data and are able to reproduce DFT observables at comparable accuracy, but negligible computational cost.
In order to actually be useful for such investigations, existing models need to be able to work across length scales and be transferable within desired temperature ranges. Here we show how models based on local mappings of electronic structure information [1], implemented in the Materials Learning Algorithms (MALA) package [2] can be trained on small number of atoms and select temperatures, yet perform accurately when used to make predictions for extended systems within a range of temperatures.

Keywords: Density Functional Theory; Machine Learning

  • Poster
    Strongly Coupled Coulomb Systems 2022, 24.-29.07.2022, Görlitz, Deutschland
  • Lecture (Conference)
    Multiscale Modeling of Matter under Extreme Conditions, 11.-16.09.2022, Görlitz, Deutschland
  • Poster
    Big data analytical methods for complex systems, 06.10.2022, Wrocław, Polen

Permalink: https://www.hzdr.de/publications/Publ-34827


Data publication: Curvilinear spin-wave dynamics beyond the thin-shell approximation: Magnetic nanotubes as a case study

Körber, L.; Verba, R.; Otálora, J. A.; Kravchuk, V.; Lindner, J.; Faßbender, J.; Kakay, A.

Abstract

This dataset contains the numerical data for our publication "Curvilinear spin-wave dynamics beyond the thin-shell approximation: Magnetic nanotubes as a case study" published in Physical Review B. The data consists of dispersion, magnetization ground states and mode profiles of spin waves in vortex-state magnetic nanotubes of different thicknesses, and has been calculated with the TetraX micromagnetic modeling package. All calculations are described within each subfolder by a jupyter notebook.

Keywords: spin waves; nanotubes; curvilinear magnetism; curvature effects; micromagnetic modeling; tetrax; nonreciprocity

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Permalink: https://www.hzdr.de/publications/Publ-34826


The M4,5 edges HERFD XANES: approaches to calculations

Amidani, L.; Kvashnina, K.

Abstract

X-ray Absorption Near-Edge Structure (XANES) in the High-Energy-Resolution Fluorescence Detected Mode (HERFD) is a very powerful technique for actinide systems. The M4,5 edges are of particular interest because they probe directly 5f states. However, before the advent of HERFD they were scarcely used because the large core-hole lifetime broadening results in broad and featureless spectra. With the improved resolution of the HERFD mode, the characterristic edge shift of different oxidation states is well resolved and several spectral features are observed in M4,5 HERFD XANES of actinides. The richness of physicochemical information coded in the spectra are hard to extract due to the complexity of XANES interpretaion and drawing conclusions on the system under study is not trivial.

In this regards, spectral calculations are fundamental for a correct interpretation. Calculating HERFD XANES on actinide systems is however particularly challenging. Relativistic effects, spin-orbit and interelectronic interactions and the influence of the atomic environment are all relevant and need to be considered in calculations. In last years, despite several approaches has been used with promising results, we still miss a theoretical framework that can address the complexity of M4,5 HERFD XANES on actinide systems.

In this presentation we will report the results we obtained with a DFT-based approach on the M4 edge of U6+ systems. Our results will be compared with works done with other approaches in order to give an overview of the level of agreement with experimental data that can be reached today. Special emphasis will be given to the investigation of covalency of 5f states.

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  • Lecture (Conference)
    Actinide revisited 2022, 21.-23.09.2022, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-34825


Magnetic-field-assisted electrodeposition at conically structured metal layers

Huang, M.

Abstract

Micro- and nano-sized conical structures possess specific magnetic, superhydrophobic and electrocatalytic properties and are therefore attractive for numerous applications. Among the various methods of manufacturing such structured layers, electrodeposition appears a simple and inexpensive method. Beside the use of capping agents, the application of magnetic fields could support the local growth of cones on a non-templated planar electrode.
This dissertation investigates electrodeposition at conically structured metal layers in external magnetic fields. Depending on the direction and the intensity of the magnetic field, the Lorentz force and the magnetic gradient force can generate electrolyte flow and bring electrolyte enriched with metal ions towards the cone tips. As a result, the local deposition rate is increased and conical growth is promoted. In order to obtain a basic understanding of the magnetic field effects, systematic numerical and theoretical investigations are performed for electrodeposition at mm-sized cones of different materials, shapes and arrangements under different electrochemical and magnetic conditions. If a uniform external magnetic field is oriented parallel to the cone axis, the magnetic gradient force enabled by the magnetization of ferromagnetic cones provides a strong support for conical growth, thereby often dominating over the Lorentz force and the buoyancy force arising from electrode reactions. This supporting effect is only slightly mitigated when neighboring cones are getting closer. The numerical results shown are validated by experimental data for different configurations and deposition parameters.
In order to explore the prospects of magnetic fields to enhance the growth of smaller, micro- and nanometer sized conical structures, scaling laws of the local flows driven by the magnetic forces are derived numerically and confirmed analytically for shrinking cone sizes. Although the magnetic gradient force can generate a beneficial flow at ferromagnetic cones, the small flow region and the nearly constant thickness of the concentration boundary layer limit the support of the magnetic field. Enhancements of the structuring effect are observed for pulsed deposition and, despite only moderately, at higher magnetic field intensities. Furthermore, a simplified modeling approach is developed to simulate the growth mechanism of nano-cones with respect to the influence of capping agents.
Experimental results of the electrodeposition of Ni cones in magnetic fields obtained by partners in Krakow are analyzed by performing simulations of both the global cell flow and the local flows generated by magnetic fields of different orientations. This two-step approach provides an interpretation of the experimental results, and gives a deeper insight on how the capping agent influences the local growth.
Finally, the impact of the hydrogen side reaction on the electrodeposition in magnetic fields is considered. The numerical results indicate that hydrogen bubbles sitting at the cone tips may damp conical growth, while the magnetic-field-driven flow imposes a weak stabilizing force on the bubble.

Keywords: Metal electrodeposition; Nano-structured catalyst; Lorentz force; Magnetic gradient force; Numerical simulation; Magnetic field

  • Doctoral thesis
    TU Dresden, 2022
    Mentor: Dr. Gerd Mutschke, Prof. Kerstin Eckert

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Permalink: https://www.hzdr.de/publications/Publ-34824


Nonlinear THz spectroscopy of two-dimensional systems

Helm, M.

Abstract

Nonlinear THz spectroscopy of two-dimensional systems (pump-probe in graphene, with and without magnetic field, dressed microcavity polaritons).

Keywords: THz; free-electron laser; graphene; Landau levels; polariton

Involved research facilities

  • F-ELBE
  • Invited lecture (Conferences)
    Workshop on "Semiconductors,nanostructures, 2D systems, and Dirac matter", 20.-22.06.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34823


Learning local dominant force balances in active particle systems

Sturm, D.; Maddu, S.; Sbalzarini, I. F.

Abstract

Systems of self-propelled particles exhibit self-organized collective behavior that leads to the formation of complex spatio-temporal patterns that can be observed all over nature — from the active self-assembly of microtubules in cells through the action of kinesin motor proteins, to flocking birds. Because of their abundance, the question of how these rich macroscopic structures emerge from the microscopic interactions of their constituents remains of central interest. While there exist several hydrodynamic theories that help better understand the physical mechanisms, it is often difficult to determine which local microscopic interactions shape and regulate self-organized structures in active particle systems. Using a combination of unsupervised clustering algorithms and sparsity-promoting inference, we learn from data dominant force balance laws that locally drive the emergence of macroscopic patterns in active particle systems. We consider a classic hydrodynamic model of self-propelled particle systems that hosts solutions composed of spatiotemporal patterns like asters and propagating stripes. We show that 1) propagating stripes are formed by local alignment interactions and driven by gradients in polarization density and 2) steady-state asters are shaped by a mechanism of splay-induced negative compressibility arising from strong particle interactions. These data-driven discoveries are in excellent agreement with analytical predictions. We therefore believe that the presented data-driven strategy, in combination with physical modeling, can help our mechanistic understanding of active material systems as well as the design of biomimetic materials.

Keywords: active particle systems; active hydrodynamics; data-driven modeling; dominant balance models

Related publications

  • Open Access Logo Lecture (Conference)
    9th GACM Colloquium on Computational Mechanics, 21.-23.09.2022, Essen, Germany
  • Open Access Logo Poster
    HZDR Doctoral Seminar 2022, 19.-21.10.2022, Wroclaw, Poland

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Permalink: https://www.hzdr.de/publications/Publ-34822


Convection triggers MRI amplitude and phase signal changes during proton beam irradiation of liquid water phantoms

Peter, J.; Gantz, S.; Karsch, L.; Pawelke, J.; Hoffmann, A. L.

Abstract

In-beam MRI has recently proven capable of visualising proton beams in liquid-filled
phantoms based on beam-induced local MR signal amplitude loss. This holds promise for on-
line beam range verification and dosimetric as well as geometric quality assurance for hybrid
MRI-proton therapy systems currently under development. The purpose of this study was
firstly to determine whether, in addition to MR signal amplitude loss, the MRI phase signal is
affected by the proton beam and secondly, to test whether these changes in MRI signals are
triggered by beam-induced convection.

Involved research facilities

  • OncoRay
  • Contribution to proceedings
    13th interventional MRI symposium 2022, 14.-15.10.2022, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34821


Combined proton radiography and irradiation for high-precision preclinical studies in small animals

Schneider, M.; Elisabeth, B.; Suckert, T.; Beyreuther, E.; Bock, J.; Dietrich, A.; Gantz, S.; Heuchel, L.; Krause, M.; Neubeck, C. V.; Nexhipi, S.; Tillner, F.; Schürer, M.; Lühr, A.; Müller, J.

Abstract

Background and purpose: Proton therapy has become a popular treatment modality in the field of radiooncology due to higher spatial dose conformity compared to conventional radiotherapy, which holds the potential to spare normal tissue. Nevertheless, unresolved research questions, such as the much debated relative biological effectiveness (RBE) of protons, call for preclinical research, especially regarding in vivo studies. To mimic clinical workflows, high-precision small animal irradiation setups with image-guidance are needed.

Material and methods: A preclinical experimental setup for small animal brain irradiation using proton radiographies was established to perform planning, repositioning, and irradiation of mice. The image quality of proton radiographies was optimized regarding the resolution, contrast-to-noise ratio (CNR), and minimal dose deposition in the animal. Subsequently, proof-of-concept histological analysis was conducted by staining for DNA double-strand breaks that were then correlated to the delivered dose.

Results: The developed setup and workflow allow precise brain irradiation with a lateral target positioning accuracy of <0.26mm for in vivo experiments at minimal imaging dose of <23mGy per mouse. The custom-made software for image registration enables the fast and precise animal positioning at the beam with low observer-variability. DNA damage staining validated the successful positioning and irradiation of the mouse hippocampus.

Conclusion: Proton radiography enables fast and effective high-precision lateral alignment of proton beam and target volume in mouse irradiation experiments with limited dose exposure. In the future, this will enable irradiation of larger animal cohorts as well as fractionated proton irradiation.

Keywords: Proton therapy; Proton radiography; Mouse brain irradiation; preclinical (in vivo) studies; DNA damage; Relative biological effectiveness (RBE)

Involved research facilities

  • OncoRay

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Permalink: https://www.hzdr.de/publications/Publ-34820


Flow Morphology of TEG Desiccant in a Structured Packing Air Dehumidifier Exposed to Floating Conditions

Mamedov, T.; Schleicher, E.; Schubert, M.; Ehlert, T.; Kenig, E. Y.; Hampel, U.

Abstract

In this work, an approach is proposed to study the influence of floating conditions on the fluid flow behavior of separation columns. A structured packing (Mellapak 250Y) air dehumidifier was embarked on a hexapod ship motion emulator with six-degree-of-freedom motions to mimic swell. A novel flow imaging sensor has been developed to visualize the flow morphology dynamics of triethylene glycol evolving on the corrugated sheets of packings. Furthermore, a numerical model was developed based on the hydrodynamic analogy concept to evaluate the separation performance using experimentally observed flow patterns. In our contribution, we describe the flow imaging sensor design as well as the impact of tilt on efficiency losses in comparison with the conventional upright stationary column.

Keywords: Moving columns; Hydrodynamics; FPSO; Flow imaging sensor; HA approach

  • Contribution to proceedings
    The 12th international conference Distillation & Absorption 2022, 18.-21.09.2022, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-34819


Liquid flow morphology investigation in structured packings for offshore applications using a novel flow imaging sensor

Mamedov, T.; Schleicher, E.; Schubert, M.; Ehlert, T.; Kenig, E. Y.; Hampel, U.

Abstract

Environmental and economic constraints for oil and gas production necessitate the development of cost-effective operating facilities in the modern offshore industry. For this reason, floating production systems are increasingly used to operate oil and gas fields in deepwater locations, whereby high submarine pipeline expenditures of fixed offshore platforms are eliminated. Apart from economic advantages, floating production systems maintain a safe operation and continuous production under severe ocean conditions, i.e. cyclones, huge waves and floating icebergs. Whilst traditional fossil energy sources are continuously losing their dominance, liquefied natural gas (LNG) is gaining popularity in the energy market owing to the comparatively lower greenhouse gas emissions. For LNG production, Floating Production Storage and Offloading (FPSO) units combine the feature of onshore LNG plants and that of storage tankers in a single large marine vessel. Thus, the number of FPSOs for LNG production has been growing in the offshore industry. The design principles for land-based process units cannot be directly applied to FPSO topside equipment because of wind-generated wave effects. Separation columns are more susceptible to the motion impact than most of the onboard process equipment, and consequent product quality losses represent the main concern.
Separation columns with structured packings are mostly used on floating platforms due to their low pressure drop, high capacity and performance. To study the dynamics of the flow morphology in the packing and the corresponding mass transfer performance, a structured packing column is embarked on a hexapod motion simulator, which mimics the six-degree-of-freedom ship motion (cf. Fig. 1). The process of air dehumidification by triethylene glycol (TEG) solutions is used as an example. A novel flow imaging sensor was developed to visualize the flow morphology dynamics evolving on the corrugated sheets of the structured packing (Fig. 2). The sensor detects most relevant morphologies, i.e. unwetted, partially and fully wetted channels and their corresponding film thicknesses on the packing sheets for the tilted and moving column allowing a comparison with the vertically oriented configuration.
At a later step, along with the fluid dynamics, the separation performance of air dehumidification and the liquid desiccant regeneration processes will be evaluated. The experimental data will be used to develop a new modelling approach for floating structured packing columns based on hydrodynamic analogies between complex flow patterns in real columns and simplified fluid-dynamic elements.

  • Contribution to proceedings
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland
    Proceedings des Jahrestreffens der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik
  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34818


Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range

Rath, S.; Unger, S.; Hampel, U.; Gampe, U.

Abstract

Power cycles based on supercritical carbon dioxide (sCO2) promise higher thermal efficiencies and more compact components than conventional technologies. Within the CARBOSOLA project, funded by the German Federal Ministry for Economic Affairs and Energy, a large-scale experimental facility is being set up by a consortium of scientific and industrial partners to actively contribute to the development of sCO2 technology. The first expansion stage provides a circulation of the sCO2 flow without expansion devices in the test loop. Thereby the compressor is intended to compensate for pressure losses and consequently for low pressure differences. In addition to that, a preferably wide operating range, regarding temperature and pressure, shall provide a high degree of flexibility of the test rig.
This work presents the design optimization of the impeller aiming at a wide operating range in compliance with the boundary conditions set for the test rig and the use of sCO2. For this purpose, a hybrid approach is used, combining parametric three-dimensional modeling with a one-dimensional performance criterion for operating range estimation. A large number of impeller designs have been simulated numerically within an optimization procedure using a genetic algorithm. On this basis, several designs have been selected and compared against each other. The evaluation includes sets of performance lines and the validation of the one-dimensional criterion used for optimization.

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  • TOPFLOW Facility
  • Open Access Logo Contribution to proceedings
    7th International sCO2 Power Cycles Symposium, 21.-24.02.2022, San Antonio, Texas, USA
    Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range
  • Open Access Logo Poster
    Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range, 21.-24.02.2022, San Antonio, Texas, USA

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Permalink: https://www.hzdr.de/publications/Publ-34817


Comparative analysis of uranium(VI) reduction by a sulfate- and an iron-reducing bacterium

Hilpmann, S.; Jeschke, I.; Steudtner, R.; Hübner, R.; Stumpf, T.; Cherkouk, A.

Abstract

The safe disposal of high-level radioactive waste represents a significant scientific and societal challenge. According to geological, geochemical, and geophysical properties, clay formations represent a suitable host rock for the long-term storage of this waste. However, for a comprehensive safety assessment, the influence of naturally occurring microorganisms in clay rock and in the backfill material bentonite must be taken into account.
Desulfosporosinus species play a crucial role in the community of sulfate-reducing bacteria present in clay rock and bentonite.[1,2] Desulfosporosinus hippei DSM 8344T is a close relative of the isolated species and was originally found in permafrost soils.[3] Desulfitobacterium sp. G1-2 has been isolated from bentonite samples and is an important representative of iron-reducing bacteria. As members of the microbial community from deep geological layers, these strains were selected to get a more profound knowledge about their interactions with U(VI).
During time-dependent experiments in bicarbonate buffer (30 mM, 100 µM U(VI)), Desulfitobacterium sp. G1-2 showed a removal of up to 80% within 5 days. UV/Vis studies of the dissolved cell pellets verified the formation of U(IV) during the process.
In contrast to these findings, Desulfosporosinus hippei DSM 8344T was not able to reduce U(VI) in the presence of bicarbonate. Therefore, experiments in artificial Opalinus Clay pore water [4] (100 µM U(VI), pH 5.5) were conducted. Determinations of the U concentrations showed a removal of up to 80% of the radionuclide from the supernatants within only 48 h. UV/Vis studies of the dissolved cell pellets provided clear proof of a partially reduction of U(VI) to U(IV), although bands of U(VI) were also still observable. These findings propose a combined association-reduction process as a possible interaction mechanism for this microorganism.
TEM images combined with EDX analysis revealed the presence of two different U-containing aggregates inside cells of Desulfitobacterium sp. G1-2. Furthermore, cells of Desulfosporosinus hippei DSM 8344T released membrane vesicles as a possible defense mechanism against encrustation by U precipitates on the cell surface. However, cells showed almost no uptake of U.
In this study, different analytical methods were used to better understand the U(VI) reduction by sulfate- and iron-reducing bacteria. Significant differences in the occurring mechanisms were evident between both microorganisms, highlighting the importance of studies on the U(VI) interactions of different microorganisms present in clay rock. Moreover, these results contribute to a safety concept for a nuclear repository in clay formations and for final disposal sites using bentonite as backfill material.

References:

[1] Bagnoud et al. (2016) Nat. Commun 7, 1–10.
[2] Matschiavelli et al. (2019) Environ. Sci. Technol. 53, 10514–10524.
[3] Vatsurina et al. (2008) Int. J. Syst. Evol. Microbiol. 58, 1228–1232.
[4] Wersin et al. (2011) Appl. Geochemistry 26, 931–953.

Keywords: Uranium(VI) reduction; Sulfate-reducing bacteria; Iron-reducing bacteria

  • Lecture (Conference)
    14th International Symposium on Nuclear and Environmental Radiochemical Analysis: ERA14, 12.-15.09.2022, York, Großbritannien

Permalink: https://www.hzdr.de/publications/Publ-34816


Simulation of particle resuspension by wind in an urban system

Banari, A.; Hertel, D.; Schlink, U.; Hampel, U.; Lecrivain, G.

Abstract

Air pollution caused by particle resuspension is a growing public health problem in many cities. Pollen and anthropogenic pollutants, such as heavy metal particles and micro-plastics debris, settle onto urban ground surfaces. Prolonged urban heat waves are propitious for heavy and continuous deposition. Particles in the submillimeter size range eventually resuspend by urban winds within seconds, may be inhaled, cause allergic reactions and escape the city's boundaries. Here, the resuspension and subsequent dispersion of generic particles ranging from 10 to 100 μm in size are simulated. The city area “Bayerischer Bahnhof” in Leipzig, Germany, has been chosen as a practical example. To track the resuspended particles, a Lagrangian model is used. Taking advantage of graphics processing unit, turbulent flow simulations at different wind speeds are performed in almost real time. The results show that particle resuspension starts, when the inlet wind speed beyond the canopy, that is at a height of 40 m, exceeds 7 m/s. At wind speed beyond 14 m/s, resuspension occurs in almost all city parts. At moderate wind speed, high-risk areas are identified. The effect of green infrastructures on both the flow field and particle resuspension is also investigated.

Keywords: particle resuspension; Bayerischer Bahnhof; public health

Permalink: https://www.hzdr.de/publications/Publ-34815


Untersuchung der Innenströmung einer Taylorblase mit einem neuartigen PIV-System mit deformierbarem Spiegel

Bürkle, F.; Lecrivain, G.; Maestri, R.; Hampel, U.; Czarske, J.; Büttner, L.

Abstract

Aerosolpartikel liegen in nahezu allen Gasen vor. Die Abscheidung dieser Partikel ist unter anderem bei der Reinigung von Luft von Feinstaub und Viren relevant. Auch in der Verfahrenstechnik reagieren beispielsweise Gase mit Feststoffen, wie bei der Gasphasenpolymerisation. Für Partikel im Größenbereich von 0,1 – 10 µm sind bisher aufgrund zu weniger empirischer Daten keine zuverlässigen Vorhersagen der Prozesse möglich.
In diesem Beitrag werden Messungen der Innenströmung einer Blase in verschiedenen, mit Wasser durchströmten Rohren gezeigt. In einem Rohr mit konstantem Durchmesser ist ein langgezogener Wirbel sichtbar. Zur Beeinflussung der Blaseninnenströmung ist in einem Rohr eine Verjüngung eingebracht. Die Verjüngung erzeugt in der Blase einen zweiten Wirbel, welcher die gleiche Rotationsrichtung aufweist. Im Berührungsbereich zwischen beiden Wirbeln treffen entgegengesetzte Strömungen aufeinander.

  • Lecture (Conference)
    29. Fachtagung "Experimentelle Strömungsmechanik", 06.-08.09.2022, Ilmenau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34814


XANES calculations of actinide-based materials

Amidani, L.; Kvashnina, K.

Abstract

XANES, with its high sensitivity to the oxidation state and the local structure, is a very powerful tool to investigate actinide-based materials. The use of the High-Energy-Resolution Fluores-cence-Detected (HERFD) mode opened new perspective in this field. By reducing the core-hole lifetime broadening, HERFD allows a relevant gain in resolution at the L3 edge and a major im-provement for M4,5 edges.
The information contained in a XANES spectrum are often hard to extract and therefore need the support of theory. However, calculations of actinide materials made complex by the compa-rable strength of intra-electronic interactions, spin-orbit and influence of the local environment. Efforts are ongoing to take all the relevant physics into account, however today none of the the-oretical framework used in XANES calculations can account for all relevant interactions over a large cluster of atoms.
If we do not yet have a unique theoretical framework that can be applied to all actinide systems, we can still select the theory that is more adapted to specific cases. In this contribution we will present progresses in the interpretation of XANES of actinide systems obtained by using the DFT–based code FDMNES [1]. Results at the L3 and M4,5 edges on Th4+ and U6+ systems will be presented [2-4]. These systems, where the intra-electronic interactions are less relevant due to the absence of 5f valence electrons, are particularly suited to investigate the importance of the local environment on the spectral shape.
Our results endorse the use of HERFD XANES coupled with DFT-based calculations to investi-gate complex actinide-containing systems.

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  • Lecture (Conference)
    ATAS-AnXAS 2022 - joint workshop, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34813


Application of laser-induced nanostructured metal surfaces

Lorenz, P.; Zajadacz, J.; Bez, E. A.; Marquardt, F.; Franz, R.; Lecrivain, G.; Peter, S.; Hommes, G.; Ehrhardt, M.; Himmerlich, M.; Zimmer, K.

Abstract

Nature teaches that nanostructured surfaces show a variety of beneficial macroscopic effects. The laser texturing of metal surfaces allows the fast, defined, and adjustable large-area nano- and micro surface structuring using ultrashort laser pulses. Such hierarchical structures comprising of determined micro patterns and self-organized nanostructures allow the customization of metal surface properties for applications in accelerators, optics, and fluidics. Here, the laser exposure of superhydrophobic SSt can cause a localized modification of the surface tension which enables the guiding and pining of water droplets which was studied using high-speed optical imaging.
The laser-induced micro- and nano structuring and the chemical modification of the metal surfaces allows the fast and defined adjustment of the macroscopic properties of metals with manifold applications.

  • Lecture (Conference)
    16th International Conference on Laser Ablation, 24.-29.04.2022, Matsue, Japan

Permalink: https://www.hzdr.de/publications/Publ-34812


Modulating properties by light ion irradiation: From novel functional materials to semiconductor power devices

Yuan, Y.; Zhou, S.; Wang, X.

Abstract

In this review, the application of light ion irradiation is discussed for tailoring novel functional materials and for improving the performance in SiC or Si based electrical power devices. The deep traps and electronic disorder produced by light ion irradiation can modify the electrical, magnetic, and optical properties of films (e.g., dilute ferromagnetic semiconductors and topological materials). Additionally, benefiting from the high reproducibility, precise manipulation of functional depth and density of defects, as well as the flexible patternability, the helium or proton ion irradiation has been successfully employed in improving the dynamic performance of SiC and Si based PiN diode power devices by reducing their majority carrier lifetime, although the static performance is sacrificed due to deep level traps. Such a trade-off has been regarded as the key point to compromise the static and dynamic performances of power devices. As a result, herein the light ion irradiation is highlighted in both exploring new physics and optimizing the performance in functional materials and electrical devices.

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Permalink: https://www.hzdr.de/publications/Publ-34811


A high-k Cu-doped ZnO film formed via Ga-ion implantation: The acceptor-donor co-doping approach

Shi, Y.-L.; Huang, D.; Kentsch, U.; Zhou, S.; Ling, F. C.-C.

Abstract

Dielectric thin films having high permittivity (high-k) and low dielectric loss is essential for developing high performance capacitive devices like metal oxide field effect transistor or thin film transistor. Ga ion implantation performed on Cu-doped ZnO film fabricated by pulsed laser deposition with optimized doping concentrations and post-implantation annealing yielded film having high permittivity and low dielectric loss (ε = 87 and tan δ = 0.17 at the frequency of 1 kHz). Moreover, the permittivity exhibits good stability over a wide range of frequency from 20 Hz to 10 MHz. The high-k film was characterized by detailed dielectric studies, including frequency dependence of permittivity and dielectric loss, complex electrical modulus analysis, impedance spectroscopy and ac conductivity. The enhancement of the permittivity was attributed to the correlated potential barrier hopping of electrons between the neighboring acceptor-donor defect complex states in the band gap created by the co-doping, thus acting as electric dipoles polarizing the film. This work opens up future possibility for ‘dielectric engineering’. The three-dimensional dielectric spatial profile can be controlled via the selective area ion implantation with the depth controlled by the ion implantation energy.

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Permalink: https://www.hzdr.de/publications/Publ-34810


Tunable structural colors in all-dielectric photonic crystals using energetic ion beams

Li, J.; Zhang, K.; Pang, C.; Zhao, Y.; Zhou, H.; Chen, H.; Lu, G.; Liu, F.; Wu, A.; Du, G.; Akhmadaliev, S.; Zhou, S.; Chen, F.

Abstract

The modulation of structural color through various methods has attracted considerable attention. Herein, a new modulation method for the structural colors in all-dielectric photonic crystals (PCs) using energetic ion beams is proposed. One type of periodic PC and two different defective PCs were experimentally investigated. Under carbon-ion irradiation, the color variation primarily originated from the blue shift of the optical spectra. The varying degrees of both the reflection and transmission structural colors mainly depended on the carbon-ion fluences. Such nanostructures are promising for tunable color filters and double-sided chromatic displays based on PCs.

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Permalink: https://www.hzdr.de/publications/Publ-34809


In-Plane Oriented Two-Dimensional Conjugated Metal–Organic Framework Films for High-Performance Humidity Sensing

Park, S.; Zhang, Z.; Qi, H.; Liang, B.; Mahmood, J.; Noh, H.-J.; Hambsch, M.; Wang, M.; Wang, M.; Hoang Ly, K.; Wang, Z.; Weidinger, I. M.; Zhou, S.; Baek, J.-B.; Kaiser, U.; Mannsfeld, S. C. B.; Feng, X.; Dong, R.

Abstract

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) have emerged as a new generation of conducting MOFs for electronics. However, controlled synthesis of thin-film samples with high crystallinity and defined layer orientation, which is beneficial for achieving high-performance devices and reliable structure–property relationship, has remained a challenge. Here, we develop a surfactant-directed two-step synthesis of layered 2D c-MOF films based on benzene and triphenylene ligands linked by copper-bis(diimino) complexes (HIB-Cu and HITP-Cu, respectively). The achieved layered 2D c-MOF films are featured as free-standing, in-plane oriented, and polycrystalline films with domain size up to ∼8000 nm2 and a tunable thickness in the range of 8–340 nm. Benefiting from the intrinsic electrical conductivity and quasi-one-dimensional pore channels, a HIB-Cu film based chemiresistive sensor is constructed, displaying effective humidity sensing with a response as fast as ∼21 s, superior to the reported MOF-powder-based chemiresistive sensors (in the orders of minutes).

Permalink: https://www.hzdr.de/publications/Publ-34808


Second harmonic generation from precise diamond blade diced ridge waveguides

Xu, H.; Li, Z.; Pang, C.; Li, R.; Li, G.; Akhmadaliev, S.; Zhou, S.; Lu, Q.; Jia, Y.; Chen, F.

Abstract

In this work, carbon ion irradiation and precise diamond blade dicing are applied for Nd:GdCOB ridge waveguide fabrication. The propagation properties of the fabricated Nd:GdCOB waveguides are investigated through experiments and theoretical analysis. The micro-Raman analysis reveals that the lattice of Nd:GdCOB crystal expands during the irradiation process. The micro-second harmonic spectroscopic analysis suggests that the original nonlinear properties of the Nd:GdCOB crystal are greatly enhanced within the waveguide volume. Under a pulsed 1064-nm laser pumping, second harmonic generation (SHG) at 532 nm have been achieved in the fabricated waveguides. The maximum SHG conversion efficiencies are determined to be ~8.32%W^-1 and ~22.36%W^-1 for planar and ridge waveguides, respectively.

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Permalink: https://www.hzdr.de/publications/Publ-34807


Single-crystal epitaxial europium iron garnet films with strain-induced perpendicular magnetic anisotropy: Structural, strain, magnetic, and spin transport properties

Guo, M. X.; Cheng, C. K.; Liu, Y. C.; Wu, C. N.; Chen, W. N.; Chen, Y. T.; Wu, C. T.; Hsu, C. H.; Zhou, S.; Chang, C. F.; Tjeng, L. H.; Lee, S. F.; Pai, C. F.; Hong, M.; Kwo, J.

Abstract

Single-crystal europium iron garnet (EuIG) thin films were epitaxially grown on gadolinium gallium garnet (GGG)(001) substrates using off-axis sputtering and showed strain-induced perpendicular magnetic anisotropy (PMA). By varying the sputtering conditions, we have tuned the europium/iron (Eu/Fe) composition ratios in the films to tailor the film strains. The films exhibited an extremely smooth, particle-free surface with a root-mean-square roughness as low as 0.1 nm, as observed by atomic force microscopy. High-resolution x-ray diffraction analysis and reciprocal space maps showed pseudomorphic film growth, a very smooth film/substrate interface, excellent film crystallinity with a rocking curve of 0.012° (ω scans), and an in-plane compressive strain without relaxation. In addition, spherical aberration-corrected scanning transmission electron microscopy showed an atomically abrupt interface between the EuIG film and GGG. The saturation magnetization (Ms) and coercive field (Hc) were measured using a vibrating sample magnetometer. The square-shaped out-of-plane M-H loops in conjunction with angle-dependent x-ray magnetic dichroism demonstrated the PMA in the films. The spin Hall magnetoresistance on Pt/EuIG samples was measured to obtain the PMA field strength (H⊥), which increases from 4.21 to 18.87 kOe with the increasing Eu/Fe ratio and in-plane compressive strain. We also measured spin transport in the Pt/EuIG bilayer structure and directly obtained the real part of spin mixing conductance to be 3.48×10^14Ω–1m–2. We demonstrated current-induced magnetization switching with a low critical switching current density of 3.5×10^6A/cm2, showing excellent potential for low-dissipation spintronic devices.

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Permalink: https://www.hzdr.de/publications/Publ-34806


Atomically Thin Delta-Doping of Self-Assembled Molecular Monolayers by Flash Lamp Annealing for Si-Based Deep UV Photodiodes

Chang, S.; He, J.; Prucnal, S.; Zhang, J.; Zhang, J.; Zhou, S.; Helm, M.; Dan, Y.

Abstract

Delta doping (δ-doping) can find a wide range of applications in advanced metal oxide semiconductor field effect transistors, deep UV photodetectors, quantum devices, and others. In this work, we formed a δ-doping layer in silicon by employing flash lamp annealing to treat the PCl3 monolayers grafted on silicon surfaces. The δ-doping layer is atomically thin (<1 nm). Low-temperature Hall measurements show that the δ-doping layer is in a metallic state and exhibits a weak localization phenomenon, implying that a two-dimensional electron gas is formed. When we form such an n-type δ-doping layer on a highly doped p-type Si substrate, a highly sensitive solar-blind UV photodetector is created, which traditionally was only possible by using wide band gap semiconductors such as gallium nitride (GaN) or silicon carbide (SiC).

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Permalink: https://www.hzdr.de/publications/Publ-34805


A mechanistic view on curium(III) sorption on natural K-feldspar surfaces

Demnitz, M.; Schymura, S.; Neumann, J.; Schmidt, M.; Schäfer, T.; Stumpf, T.; Müller, K.

Abstract

For a reliable safety assessment for future deep underground repositories for highly active nu-clear waste a comprehensive understanding of the radionuclide retention by the surrounding host rock is required. Several parameters such as mineral heterogeneity and surface roughness, as well as pore water chemistry, influence radionuclide retention. Although many studies have been performed to investigate individual parameters, their interplay with each other is not yet well understood.

In our study, we focus on the sorption of trivalent curium on K-feldspar, a representative for the large alkali feldspar fractions contained in most crystalline rocks. We use cleaved macroscopic K-feldspar crystals and perform experiments at different pH values (5.5 and 6.9) to determine its impact on surface sorption with varying surface roughness. Furthermore, we investigate a K-feldspar mineral grain, which is part of a complex heterogeneous crystalline rock, obtained from the Grimsel Test Site.

To assess the sorption dependencies, we apply a correlative spectromicroscopy approach. In de-tail, the topography and surface roughness of the K-feldspar crystals as well as the mineral thin section is determined by vertical scanning interferometry. In addition, Raman microscopy deliv-ers information about the thin section’s surface mineralogy. The quantitative amount of sorbed Cm(III) is obtained by calibrated autoradiography and partially µTRLFS (micro-focus time-resolved laser-induced fluorescence spectroscopy), which is also the only method capable of measuring Cm(III) surface speciation on the molecular level via analysis of luminescence spec-tra and lifetimes.

Our results indicate that rougher K-feldspar surfaces exhibit increased Cm(III) uptake and stronger surface complexation. Similarly, the increase in pH leads to higher surface loading and stronger Cm(III) binding to the surface. Results obtained on the thin section reveal, that within a heterogeneous mineralogical system, sorption is affected by dissolution of neighboring minerals and competitive sorption between different mineral phases, such as mica and feldspar. The ob-tained findings express a need for investigating relevant processes on multiple scales of dimen-sion and complexity to better understand radionuclide retention by potential repository host rocks.

The authors acknowledge funding provided by the German Federal Ministry of Education and Research (iCross project 02NUK053B), the Helmholtz Association (iCross project SO-093 and CROSSING project PIE-0007), as well as by the German Federal Ministry of Economics and Technology (SMILE project 02E11668B). We thank F. Bok R. Moeckel, S. Beutner and S. Schöne.

Keywords: µTRLFS; correlative spectroscopy; microscopy; Cm(III); feldspar; orthoclase

  • Contribution to proceedings
    ATAS-AnXAS 2022 - Joint Workshop, 17.-21.10.2022, Grenoble, France
  • Poster
    ATAS-AnXAS 2022 - Joint Workshop, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34804


Two decades of CW SRF operation at ELBE

Arnold, A.

Abstract

ELBE is a compact, accelerator-driven photon and particle source. The variety of secondary radiation being offered extends from high-energy gamma rays to infrared and THz radiation as well as from neutrons to positrons and electrons. Since 2001 ELBE is operated as a user facility, providing more than 5500 hours of beamtime with an efficiency of more than 90% each year. The electron accelerator is based on four superconducting 9-cell TESLA cavities that are driven in CW operation to accelerate an average current of 1 mA up to beam energies of 40 MeV.

The the talk will summarize our experiences of operating TESLA cavities over two decades in CW. In detail, this includes the cavity performance and attempts to improve it, as well as investigations on their limitations. Additionally, we will discuss several issues that are related to the high average RF as well as beam power and we will present appropriate measures to protect the machine. In this regard we will also report on long-term experiences with our 10kW 1.3 GHz solid state power amplifiers and introduce a resonant ring for RF component tests at CW power levels up to 100 kW.

Keywords: ELBE; CW SRF; TESLA cavity

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  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    e-LINAC Reliability Workshop (ERW), 09.-10.05.2022, Vancouver, Canada

Permalink: https://www.hzdr.de/publications/Publ-34802


Overview of SRF gun developments in Germany and perspectives of high charge (1 nC) operation

Arnold, A.

Abstract

The contribution highlights the developments of superconducting radio frequency photo electron source (SRF gun) in Germany. The success at HZDR, as well as the progress at HZB and DESY are discussed. The presentation completes with detailed beam dynamics simulations for the typical bunch charges and an gives perspectives of high charge (1 nC) operation.

Keywords: SRF gun; superconducting radio frequency photo electron source

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  • Invited lecture (Conferences)
    FELs of Europe - Topical Workshop on selected problems in FEL physics: from soft X‐rays to THz, 25.-27.04.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34801


A scalable pipeline for COVID-19: the case study of Germany, Czechia and Poland

Abdussalam, W.; Mertel, A.; Fan, K.; Schüler, L.; Schlechte-Welnicz, W.; Calabrese, J.

Abstract

Throughout the coronavirus disease 2019 (COVID-19) pandemic, decision makers have relied on forecasting models to determine and implement non-pharmaceutical interventions (NPI). In building the forecasting models, continuously updated datasets from various stakeholders including developers, analysts, and testers are required to provide precise predictions. Here we report the design of a scalable pipeline which serves as a data synchronization to support inter-country top-down spatiotemporal observations and forecasting models of COVID-19, named the \textit{where2test}, for Germany, Czechia and Poland. We have built an operational data store (ODS) using PostgreSQL to continuously consolidate datasets from multiple data sources, perform collaborative work, facilitate high performance data analysis, and trace changes. The ODS has been built not only to store the COVID-19 data from Germany, Czechia, and Poland but also other areas. Employing the dimensional fact model, a schema of metadata is capable of synchronizing the various structures of data from those regions, and is scalable to the entire world. Next, the ODS is populated using batch Extract, Transfer, and Load (ETL) jobs. The SQL queries are subsequently created to reduce the need for pre-processing data for users. The data can then support not only forecasting using a version-controlled Arima-Holt model and other analyses to support decision making, but also risk calculator and optimisation apps. The data synchronization runs at a daily interval, which is displayed at https://www.where2test.de.

Keywords: COVID-19; Database Server; Data warehouse; Data pipeline; Database model; Forecast

  • Open Access Logo Contribution to proceedings
    DEco - First International Workshop on Data Ecosystems in conjunction with very large databases, 05.-09.09.2022, Sydney Hybrid, Australia
    Proceedings of DEco
    DOI: 10.48550/arXiv.2208.12928
    URN: https://ceur-ws.org/Vol-3306/

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Permalink: https://www.hzdr.de/publications/Publ-34800


Numerische Simulation der Zweiphasenströmung an einem Festventil eines Kolonnenbodens

Wiedemann, P.; Schubert, M.; Hampel, U.

Abstract

Die zunehmende Energieversorgung aus regenerativen Quellen erfordert ein höheres Maß an Flexibilität beim Betrieb thermischer Trennkolonnen. Vor diesem Hintergrund werden Bodenkolonnen vermehrt mit Festventilen ausgestattet, da diese im Vergleich zu anderen Bodentypen auch bei Teil- oder Überlastfahrweisen eine hohe Trenneffizienz aufweisen. Die Auslegung solcher Böden stellt in der Praxis jedoch eine Herausforderung dar, da es bislang an verlässlichen Daten und Methoden mangelt, um den Einfluss der Ventilanordnung auf die komplexe Zweiphasenströmung abzuschätzen. Im Rahmen eines aktuellen Forschungsprojektes soll daher ein grobskaliger CFD-Ansatz entwickelt werden, mit dessen Hilfe Strömungsszenarien auf Festventilböden mit vertretbarem Aufwand vorausberechnet werden können.
Im vorliegenden Beitrag werden erste Ergebnisse der Verwendung eines hybriden Modellierungsansatzes vorgestellt, mit dem sowohl disperse Strukturen als auch aufgelöste Phasengrenzflächen innerhalb einer Simulationsumgebung abgebildet werden können. Beispielhaft wird dieses Morphologie-adaptive Mehrfeld-Zweifluid-Modell hier zur Simulation der Strömung an einem einzelnen Festventil eingesetzt. Die Abbildung des Ventils erfolgt dabei nicht durch die Auflösung seiner Geometrie im Rechengitter, sondern durch die Implementierung lokaler Massen- und Impulsquellen in der Gasphase. Zur Verifikation der Simulationsergebnisse werden experimentelle Daten der Phasenverteilung um ein Ventil herangezogen, die an einem mit Luft und Wasser betriebenen Laborversuchstand mit einem Leitfähigkeitssensorarray erfasst wurden. Der Vergleich zeigt, dass die im zeitlichen Mittel auftretenden Phasengrenzflächen bei Verwendung statischer Quellterme bereits zufriedenstellend abgebildet werden können. Zur angemessenen Vorhersage des transienten Verhaltens ist jedoch eine Einbeziehung dynamischer Parameter erforderlich. Hierfür können beispielsweise experimentell ermittelte Ablösefrequenzen der Gasblasen vom Ventil verwendet werden. In weiterführenden Arbeiten soll der vielversprechende Ansatz zunächst auf Ventilgruppen und schließlich auf Böden im industriellen Maßstab übertragen werden.

Keywords: Numerische Simulation; Hybrides CFD Model; Festventil; Destillationskolonne

  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt a.M., Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34799


Recent technical developments in ASL: A Review of the State of the Art

Hernandez-Garcia, L.; Aramendia, V.; Dai, W.; Bolar, D.; Fernández-Seara, M. A.; Guo, J.; Madhuranthakam, A. J.; Mutsaerts, H.; Petr, J.; Qin, Q.; Schollenberger, J.; Suzuki, Y.; Taso, M.; Thomas, D. L.; van Osch, M. J. P.; Woods, J.; Zhao, M. Y.; Yan, L.; Wang, Z.; Zhao, L.; Okell, T. W.

Abstract

This review article provides an overview of a range of recent technical developments in
advanced arterial spin labeling (ASL) methods that have been developed or adopted by
the community since the publication of a previous ASL consensus paper by Alsop et al.
1 . It is part of a series of review/recommendation papers from the International Society
for Magnetic Resonance in Medicine (ISMRM) Perfusion Study Group. Here, we focus
on advancements in readouts and trajectories, image reconstruction, noise reduction,
partial volume correction, quantification of non-perfusion parameters, fMRI,
fingerprinting, vessel selective ASL, angiography, deep learning, and ultra-high field
ASL. We aim to provide a high level understanding of these new approaches and some
guidance for their implementation, with the goal of facilitating the adoption of such
advances by research groups and by MRI vendors. Topics that are outside the scope of
this article, and are reviewed at length in separate articles, include velocity selective
ASL, multiple-timepoint ASL, body ASL, and clinical ASL recommendations.

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  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-34798


A new tomography-based approach for the fluid dynamic description of conventional structured packings and sandwich packings

Flechsig, S.; Sohr, J.; Schubert, M.; Hampel, U.; Kenig, E. Y.

Abstract

Pressure drop, holdup and flooding points are essential factors for the hydraulic design of columns equipped with structured packings. This is also true for sandwich packings representing a combination of two alternating layers of conventional structured packings with different geometric surface areas. Such a combination results in a heterogeneous flow pattern evolving within certain operating ranges. In order to describe accurately the fluid dynamics over the entire operating range of both common structured packings and sandwich packings, a modelling approach is proposed based on conventional measurements and tomographic investigations. The approach distinguishes film-like flow patterns and froth regimes. For film-like flow patterns, packing-typical descriptions are used, whereas the froth in packings is described using an analogy to trays. Correlations were derived to determine the liquid holdup for film and froth flow, the dry and irrigated pressure drop as well as the gas velocities at the loading limits. The fluid dynamic model was verified with 1595 measurements for pressure drop and 510 measurements for holdup for the test system water/air.

Keywords: fluid dynamics; modelling; sandwich packings; structured packings; tomography

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  • TOPFLOW Facility

Permalink: https://www.hzdr.de/publications/Publ-34797


Investigation of the interaction of uranium(VI) with the biofluids of the human digestive system

Butscher, D.; Steudtner, R.; Stumpf, T.; Barkleit, A.

Abstract

When radionuclides (RNs) enter the food chain and are ingested by humans, they pose a potential health risk due to their radio- and chemotoxicity. After oral ingestion, RNs first come into contact and interact with the biofluids of the digestive system. For the development of a rapid as well as ef-ficient method for the decorporation of RNs, it is necessary to know the biokinetic processes as well as the speciation in the digestive system. Therefore, the aim of this work was to investigate the in-teractions of uranium(VI) with the biofluids of the human digestive system, with the gastrointesti-nal digestive segments stomach and small intestine as well as the whole digestive system at the mo-lecular level. To simulate the biofluids, saliva, gastric juice, pancreatic juice and bile, and the diges-tive segments were synthesized based on human physiology.[1] For the determination of chemical speciation, luminescence spectra were measured using time-resolved laser-induced fluorescence spectroscopy under cryogenic conditions (cryo-TRLFS) at 153 K. Species distribution was then de-termined by parallel factor analysis (parafac), where the resulting species were assigned using the spectra of the individual complexes. These results were compared with thermodynamic modeling.
Based on the TRLFS experiments, it can be shown that the speciation of uranium is predominantly dominated by the inorganic components, mainly carbonate and to a smaller extent phosphate. Among the organic components, only the protein mucin is involved in speciation at acidic pH val-ues, such as in the stomach. Therefore, the complexation of mucin with uranium(VI) was investi-gated in more detail.

This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and is part of the joint project RADEKOR.

[1] Wilke, C. et al. (2017) J. Inorg. Biochem. 175, 248-258.

  • Lecture (Conference)
    ATAS-AnXAS workshop 2022, 17.-21.10.2022, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-34796


Assessing the impact of forest structure disturbances on the arboreal movement of orangutans - an agent-based modelling approach

Widyastuti, K.; Reuillon, R.; Chapron, P.; Abdussalam, W.; Nasir, D.; Harrison, M. E.; Morrogh-Bernard, H.; Imron, M. A.; Berger, U.

Abstract

Orangutans encounter habitat quality deterioration due to land-use changes and associated forest fires. This creates a complex stress scenario for the individual animals and threatens populations. The disturbance of forest canopies or loss of trees induce changes in primates' movement behavior: the preferred arboreal movement needs to be complemented by movements on the ground requiring more energy, and prolonging the search for fruiting and nesting trees. This all together leads to a change in the daily activity patterns (time spent to travel, feeding and resting) and subsequently to shift in the available energy budget decreasing the fitness of the animals. While agent-based models have been developed and widely employed to check the impact of disturbances or conservation management on the habitat use, population development and viability, there has been less emphasis on studying the direct impact of canopy disturbances on the arboreal movement of individual primates, which can be the origin of cascading effects on animals health, vitality and subsequent life processes. We developed the agent-based simulation model BORNEO (arBOReal aNimal movEment mOdel), which explicitly describes both orangutans' arboreal and terrestrial movement between trees in a forest depending on distances among trees and canopy structure. Orangutans in the model perform activities with a motivation to balance energy intake and expenditure involving mechanical work of locomotion. The model was tested with forest inventory data obtained in Sebangau National Park, Central Kalimantan, Indonesia. Information on tree constellations, sizes etc. were used to reconstruct a virtual forest with similar characteristics (e.g., trees network in terms of connections between overlapping canopies) as in the real world. In order to parameterise the energy related processes of the orangutans described in the model, we applied a computationally intensive evolutionary algorithm on high computing clusters and evaluated the simulation results against behavioural patterns of the orangutans observed in Sebangau. Both the simulated variability and proportion of activity budgets including feeding, resting, and travelling time for female and male orangutans respectively, confirmed the suitability of the model for its purpose. We used the calibrated model to compare the activity patterns and energy budgets of orangutans in both natural and disturbed forests. The results confirm field observations that orangutans in the disturbed forest are prone to experiencing deficit energy balance by spending more time travelling and less time feeding. The finding of a threshold of forest disturbances which affects a significant change in the activity pattern points out that forest deterioration may even threaten the survival of orangutans to some extent.

Our study (a) introduces the first agent-based model describing the arboreal movement of primates and can serve as a tool to investigate the direct impact of forest changes and disturbances on the behaviour of orangutans; and (b) demonstrates the suitability of high-performance computing to optimise the calibration of complex agent-based models describing animal behaviour at a fine spatiotemporal scale (1-meter and 1-second granularity).

Keywords: orangutan; forest structure; peatland; primates; energy budget; agent-based model; 39 calibration; optimisation; distributed computing

Permalink: https://www.hzdr.de/publications/Publ-34795


Data publication: Numerical simulation of tidal synchronization of the Large-Scale Circulation in Rayleigh-Bénard Convection with aspect ratio 1

Röhrborn, S.; Jüstel, P.; Galindo, V.; Stefani, F.; Stepanov, R.

Abstract

wichtige Simulationsdaten + Bilder

Keywords: Magnetohydrodynamics; Rayleigh-Bénard convection; liquid metal flow; electromagnetic forcing; CFD

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Permalink: https://www.hzdr.de/publications/Publ-34794


Data publication: Analyzing a modulated electromagnetic m=2 forcing and its capability to synchronize the Large Scale Circulation in a Rayleigh-Bénard cell of aspect ratio Г = 1

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

Abstract

Relevante Simulationsdaten + Bilder

Keywords: Magnetohydrodynamics; Rayleigh-Bénard convection; liquid metal flow; electromagnetic forcing; CFD

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Permalink: https://www.hzdr.de/publications/Publ-34793


Data publication: Lanmodulin Peptides – Unravelling the Binding of the EF-Hand Loop Sequences Stripped from the Structural Corset

Gutenthaler, S. M.; Tsushima, S.; Steudtner, R.; Gailer, M.; Hoffmann-Röder, A.; Drobot, B.; Daumann, L. J.

Abstract

Daten für die Publikation

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Permalink: https://www.hzdr.de/publications/Publ-34792


Recovery of fine gold loss to tailings using advanced reactor pneumatic flotation ImhoflotTM

Hoang, D. H.; Imhof, R.; Sambrook, T.; Bakulin, E. A.; Murzabekov, M. K.; Abubakirov, A. B.; Baygunakova, K. R.; Rudolph, M.

Abstract

Gold concentration usually consists of gravity separation and froth flotation. However, flotation faces difficulties due to gold-bearing ores often being refractory and finely disseminated in nature. Poor recovery and low flotation kinetics of fine particles are mainly due to the low frequencies of particle-bubble collisions and an increase in entrainment of fine gangue particles decreases the grade. In this study, applications of two pilot ImhoflotTM G-14 (tangential feed to the separator vessel with 1.4 m diameter) cells in an open circuit demonstrated its ability to recover fines with high gold grade and achieved a high recovery of 65–68 % for the particle size fraction of −20 µm. The gold content in the −20 µm fraction of tailings is only about 0.36 g/t, which is lower than in the existing flotation circuit (0.47 g/t), including rougher and scavenger banks. Furthermore, bubble size measurements indicate that pneumatic ImhoflotTM generated very fine bubbles in a high shear environment, improving particle-bubble collision frequencies.

Keywords: pneumatic flotation; G-cell; gold tailings; reactor-separator; fine bubbles; high shear

Permalink: https://www.hzdr.de/publications/Publ-34791


Data publication: A machine learning approach to determine bubble sizes in foam at a transparent wall

Knüpfer, L.; Heitkam, S.

Abstract

Images which has been used to train the model as well as the trained model weights.

Keywords: bubble; foam; image segmentation

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Permalink: https://www.hzdr.de/publications/Publ-34790


A minimal-invasive method for the evaluation of liquid fractions in foams with a point level sensor

Staud, R.; Heller, D.; Knüpfer, L.; Heitkam, S.; Einfalt, D.; Jasch, K.; Scholl, S.

Abstract

Liquid foams occur whether intentionally or unintentionally across different industrial sectors. The detection of foam and characterization of its liquid content currently requires complex measurement methods such as electrical conductivity measurements. This paper presents a novel method for foam detection and characterization of its liquid fraction based on a capacitive level sensor. A correlation between the sensor output signal and defined liquid fractions of dry to wet foam indicated a high accuracy of this sensor technique. Regarding the sensor operation in different liquid solutions, a minimum screw-in depth is presented. The sensor allows minimal invasive inline measurements in equipment regardless of the wall material and extreme process conditions e.g. explosion hazard areas.

Keywords: foam; liquid fraction; sensor

Permalink: https://www.hzdr.de/publications/Publ-34789


PET imaging of cannabinoid receptors type 2 (CB2R) in an animal model of local CB2R overexpression

Rareş-Petru, M.

Abstract

The development PET radioligands for imaging of the cannabinoid type 2 receptors (CB2R) has been intensively explored due to their upregulation in various pathological conditions [1]. Recently, we reported the development of [18F]JHU94620 [2], however, this radioligand suffered from low metabolic stability in vivo. Here, we describe the development of the deuterated analogues [18F]JHU94620-d4 and -d8 as well as their biological evaluation (Figure 1). The precursors for radiofluorination were obtained by coupling 4,5-dimethylthiazol-ylidene-2,2,3,3-tetramethylcyclopropane-1-carboxamide with either d4 or d8 1,4-butanediol-bistosylate and radiofluorinated in the presence of Kryptand K2.2.2. and K2CO3. [18F]JHU94620-d4 and -d8 were obtained in 10% radiochemical yield and >99% radiochemical purity. The fraction of radiometabolites was quantified in mice plasma, brain and spleen of CD1 mice at 30 min p.i. Both [18F]JHU94620-d4 and -d8 demonstrated an improved metabolic stability with 80% intact radioligand detected in the brain vs. 36% for [18F]JHU94620. The CB2 affinity and specificity of [18F]JHU94620-d8 was determined by in vitro binding experiments and a KD(rCB2) of 0.36 nM was determined. Additionally, we evaluated the [18F]JHU94620-d8 uptake by PET-studies into the spleen of healthy rats and in a rat model carrying an adeno-associated viral (AAV2/7) vector expressing hCB2R(D80N) at high densities in the right striatum (hCB2-rs) [3, 4]. Our PET study with [18F]JHU94620-d8 revealed a rCB2 specific uptake into the spleen (AUC0-30min = 33 vs. 17 SUV min after blocking with GW405833). In the hCB2-rs model we could show a target specific uptake of [18F]JHU94620-d8 with a constant SUV of 6.7±0.3 from 6 to 60 min p.i. and an SUVr (right striatum-to-cerebellum) of 43±7at 60 min p.i., as well as a reversible binding in displacement studies. Thus, [18F]JHU94620-d8 is a new PET tracer with improved metabolic stability and excellent ability to image the CB2 receptors in-vivo. Its further evaluation is underway.

  • Invited lecture (Conferences)
    Advancing cancer nanomedicine to the clinics: hypes, hopes and hurdles, 16.-17.06.2022, Magdeburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34787


Comparative Analysis of Mononuclear 1:1 and 2:1 Tetravalent Actinide (U, Th, Np) Complexes: Crystal Structure, Spectroscopy, and Electrochemistry

Bansal, D.; Kaden, P.; Patzschke, M.; März, J.; Schmidt, M.

Abstract

Six mononuclear tetravalent actinide complexes (1-6) have been synthesized using a new Schiff base ligand 2-methoxy-6-(((2-methyl-1-(pyridin-2-yl)propyl)imino)methyl)phenol (HLpr). The HLpr is treated with tetravalent actinide elements in varied stoichiometry to afford mononuclear 1:1 complexes [MCl3-Lpr∙nTHF] (1-3) and 2:1 complexes [MCl2-Lpr2] (4-6) (M = Th4+ (1 and 4), U4+ (2 and 5) and Np4+ (3 and 6)). All complexes are characterized using different analytical techniques such as IR, NMR, and absorption spectroscopy as well as crystallography. UV-vis spectroscopy revealed more red-shifted absorption spectra for 2:1 complexes as compared to 1:1 complexes. 1H NMR of Th(IV) complexes exhibit diamagnetic spectra whereas U(IV) and Np(IV) complexes revealed paramagnetically shifted 1H NMR. Interestingly, NMR signals are paramagnetically shifted between -70 to 40 ppm in 2 and 3, but are confined within -35 to 25 ppm in 2:1 complexes 5 and 6. Single crystal structures for 1:1 complexes revealed an eight-coordinated Th(IV) complex (1) and seven-coordinated U(IV) (2) and Np(IV) (3) complexes. Whereas, all 2:1 complexes 4-6 were isolated as eight-coordinated isostructural molecules. The geometry around the Th4+ center in 1 is found to be trigonal dodecahedral and, capped trigonal prismatic around U(IV) and Np(IV) centers in 2 and 3, respectively. Whereas, An4+ centers in 2:1 complexes are present in dodecahedral geometry. Importantly, 2:1 complexes exhibit increased bond distances in comparison to their 1:1 counterparts as well as interesting bond modulation w.r.t. ionic radii of An(IV) centers. Cyclic voltammetry displays an increased oxidation potential of the ligand by 300 to 500 mV, after coordination with An4+. CV studies indicates Th(IV)/Th(II) reduction beyond −2.3 V whereas attempts were made to identify redox potentials for U(IV) and Np(IV) centers. Spectroscopic binding studies reveal that complex stability in 1:1 stoichiometry follows the order Th4+≈ U4+ > Np4+.

Keywords: Actinides; Coordination; Electrochemistry; Crystal structure

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Permalink: https://www.hzdr.de/publications/Publ-34786


Data publication: Spin-resolved density response of the warm dense electron gas

Dornheim, T.

Abstract

This repository contains the PIMC results from the article "Spin-resolved density response of the warm dense electron gas"; parameters are given in the file names; all results are unpolarized (Xi=0) unless otherwise stated; same units as in the original publication.

Keywords: Path integral Monte Carlo; Uniform electron gas; Linear response theory; spin effects

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Permalink: https://www.hzdr.de/publications/Publ-34785


Bomb-pulse radiocarbon record for a well-dated Caribbean coral core

Winkler, S.; Steier, P.; Carilli, J.

Abstract

The radiocarbon bomb-pulse created by nuclear weapons testing in the 1950s and 1960s has created a massive spike of atmospheric ¹⁴C, which has been used in the study of the global carbon cycle in many subsystems including the marine environment. Coral records of bomb-pulse era ¹⁴C have been studied over the past decades to gain insight into the uptake and mixing of atmospheric CO₂ in the ocean. The ¹⁴C level seen in surface waters is specific to the origin of the water masses and ocean-atmosphere exchange of CO₂.
We present results for radiocarbon levels in coral aragonite with yearly resolution for a coral core from Belize. The core has a well-established stratigraphy, stretching from the onset of atmospheric testing of thermonuclear devices to 2007. The core has previously been analyzed for and trace metal content in relation to environmental impacts and the bomb-pulse of ²³⁶U. We compare the results with existing results and model expectations for the Caribbean Sea. We further discuss the close agreement for the prior results in terms of feasibility and the achievable accuracy of cross-dating of cores using the rise of radiocarbon by the atmospheric bomb-pulse.

  • Poster
    Radiocarbon International Conference, 11.-16.09.2022, Zürich, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-34784


Electronic pair alignment and roton feature in the warm dense electron gas

Dornheim, T.

Abstract

The study of matter under extreme densities and temperatures as they occur e.g. in astrophysical objects and nuclear fusion applications has emerged as one of the most active frontiers in physics, material science, and related disciplines. In this context, a key quantity is given by the dynamic structure factor S(q,ω), which is probed in scattering experiments -- the most widely used method of diagnostics at these extreme conditions. In addition to its crucial importance for the study of warm dense matter, the modeling of such dynamic properties of correlated quantum many-body systems constitutes one of the most fundamental theoretical challenges of our time. Here we report a hitherto unexplained roton feature in S(q,ω) of the warm dense electron gas [1], and introduce a microscopic explanation in terms of a new electronic pair alignment model [2]. This new paradigm will be highly important for the understanding of warm dense matter, and has a direct impact on the interpretation of scattering experiments. Moreover, we expect our results to give unprecedented insights into the dynamics of a number of correlated quantum many-body systems such as ultracold helium, dipolar supersolids, and bilayer heterostructures.

  • Lecture (Conference)
    The 13th International Conference on High Energy Density Laboratory Astrophysics (HEDLA) 2022, 25.05.2022, Lisbon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-34783


Data publication: Effective electronic forces and potentials from ab initio path integral Monte Carlo simulations

Dornheim, T.

Abstract

This repository contains all path integral Monte Carlo (PIMC) results for the article "Effective electronic forces and potentials from ab initio path integral Monte Carlo simulations" in the same units as they are plotted in Figs. 4, 5 and 8.

Keywords: Path integral Monte Carlo; Uniform electron gas; effective force

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Permalink: https://www.hzdr.de/publications/Publ-34782


I-V-T Characteristics and Temperature Sensor Performance of a Fully-2D WSe2/MoS2 Heterojunction Diode at Cryogenic Temperatures

Matthus, C. D.; Chava, P.; Watanabe, K.; Taniguchi, T.; Mikolajick, T.; Helm, M.; Erbe, A.

Abstract

In this work, we demonstrate the usability of a fully-2D-material based device consisting of MoS2/WSe2 heterojunction encapsu-lated by hBN and contacted by graphene as temperature sensor for linear temperature measurement at cryogenic temperatures. More precisely, temperatures in the range of 10 K up to 300 K were applied to the device while recording the I-V characteris-tics. From this, we had a deeper look on the current transport mechanism by obtaining the activation energy of the saturation current in the Arrhenius diagram. It is 1.3 eV, which can be related to the bandgap of MoS2 or WSe2 (both nominal 1.3 eV) as for traditional pn-junction diodes in bulk materials. Further-more, we applied a constant forward current to the device while measuring the voltage drop at different temperatures to investi-gate the temperature-sensor performance. In the range of 40 K up to 300 K, the sensitivity of the sensor is ~2 mV/K, which is comparable to Si devices, while the linearity is still lower (R2 ~ 0.94). On the other hand, the demonstrated device consists only of 2D materials and is, thus, substrate independent, ultra-thin, and can be fabricated on a fully flexible substrate in a low-cost process.

Keywords: Temperature sensing; 2D-material diode; hetero-junction; flexible sensor

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Permalink: https://www.hzdr.de/publications/Publ-34781


Data publication: Distinguishing local demagnetization contribution to the magnetization process in multisegmented nanowires

Marqués Marchán, J.; Fernandez Roldan, J. A.; Bran, C.; Puttock, R.; Barton, C.; Moreno, J. A.; Kösel, J.; Vazquez, M.; Kazakova, O.; Chubykalo-Fesenko, O.; Asenjo, A.

Abstract

Article and Suplementary information available on the Open Access Journal:https://www.mdpi.com/2079-4991/12/12/1968/htm

Figure S1: Nonstandard 2D MFM images of a single NW for an applied magnetic field of (a) ±47 mT and (b) ±28 mT;
Figure S2: (a) Sketch of two simulated CoNi/Cu NWs with different segments and Cu layer lengths. (b) Hysteresis loops of NWs with different anisotropies (68° and 65° with respect to NW axis) and geometries as shown in (a). (c) Zoom of hysteresis loops of NWs with anisotropy at 65° and different geometries.

Keywords: magnetic nanowires; magnetization reversal processes; magnetoresistance; Magnetic Force Microscopy (MFM); CoNi; Cu; nanomagnetism; spintronics

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Permalink: https://www.hzdr.de/publications/Publ-34779


Accelerating Equilibration in First-Principles Molecular Dynamics with Orbital-Free Density Functional Theory

Fiedler, L.; Moldabekov, Z.; Shao, X.; Jiang, K.; Dornheim, T.; Pavanello, M.; Cangi, A.

Abstract

We introduce a practical hybrid approach that combines orbital-free density functional theory (DFT) with Kohn-Sham DFT for speeding up first-principles molecular dynamics simulations. Equilibrated ionic configurations are generated using orbital-free DFT for subsequent Kohn-Sham DFT molecular dynamics. This leads to a massive reduction of the simulation time without any sacrifice in accuracy. We assess this finding across systems of different sizes and temperature, up to the warm dense matter regime. To that end, we use the cosine distance between the time series of radial distribution functions representing the ionic configurations. Likewise, we show that the equilibrated ionic configurations from this hybrid approach significantly enhance the accuracy of machine-learning models that replace Kohn-Sham DFT. Our hybrid scheme enables systematic first-principles simulations of warm dense matter that are otherwise hampered by the large numbers of atoms and the prevalent high temperatures. Moreover, our finding provides an additional motivation for developing kinetic and noninteracting free energy functionals for orbital-free DFT.

Keywords: Density Functional Theory; Machine Learning

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Permalink: https://www.hzdr.de/publications/Publ-34778


Stable Multi-Day Performance and Diagnosis of the DRACO Laser Wakefield Accelerator for Secondary Applications

Couperus Cabadağ, J. P.; Bock, S.; Chang, Y.-Y.; Debus, A.; Gebhardt, R.; Helbig, U.; Irman, A.; Koehler, A.; Kurz, T.; Guntram Pausch, R.; Püschel, T.; Schoebel, S.; Ufer, P.; Zarini, O.; Zeil, K.; Lumpkin, A.; Schramm, U.; Ghaith, A.; Downer, M.; Laberge, M.

Abstract

We report on the operation of the DRACO Laser Driven electron source for stable multi-day operation of secondary applications with demanding beam requirements. The nC-class accelerator delivers charge densities around 10 pC/MeV*, 1 mrad rms divergence at energies up to 0.5 GeV and peak currents of over 10kA**. Precise characterisation is paramount for controlled operation of demanding applications, this includes: spectrally resolved charge diagnostic, source size diagnostics based both on betatron radiation*** as well as on coherent optical transition radiation (TR) to resolve microbunch beam structures**** and TR-based multioctave high-dynamic range spectrometry for sub-fs resolved characterisation of the 10 fs rms electron bunches**. Achieved stability allows systematic exploration of applications, resulting in the recent demonstration of the first LWFA based Beam-driven Plasma Wakefield Accelerator*****. In an effort toward LWFA based Free Electron Lasing, the COXINEL manipulation line developed at Synchrotron SOLEIL was recently installed at our facility. At initial commissioning, successful beam transport was achieved with over 13000 delivered shots within 9 experimental days.

* J.P. Couperus et al., Nat. Comm. 8 (2017)
** O. Zarini et al., PRAB (2022)
*** A. Köhler et al., PRAB (2021)
**** A. Lumpkin et al., PRL 125 (2020)
***** T. Kurz et al., Nat. Comm. 12 (2021)

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  • Draco
  • Poster
    13th International Particle Accelerator Conference (IPAC’22), 12.-17.06.2022, Bangkok, Thailand

Permalink: https://www.hzdr.de/publications/Publ-34777


Untersuchung der Wechselwirkung von Uran(VI) mit den Biofluiden des menschlichen Verdauungssystems sowie mit Nierenzellen

Butscher, D.; Senwitz, C.; Steudtner, R.; Heller, A.; Stumpf, T.; Barkleit, A.

Abstract

Wenn Radionuklide (RN) in die Nahrungskette gelangen und vom Menschen aufgenommen werden, stellen sie aufgrund ihrer Radio- und Chemotoxizität ein mögliches Gesundheitsrisiko dar. Dabei kommen die RN nach der oralen Aufnahme zuerst mit den Biofluiden des Verdauungssystems in Kontakt und interagieren mit diesen. Die Ausscheidung der Schwermetalle erfolgt größtenteils renal. Für die Entwicklung einer schnellen sowie effizienten Methode zur Dekorporation der RN ist es notwendig, die biokinetischen Prozesse sowie die Speziation im Verdauungs- und Ausscheidungssystem zu kennen. Ziel dieser Arbeit ist es daher, die Wechselwirkungen von Uran(VI) mit den Biofluiden des menschlichen Verdauungssystems, mit den gastrointestinalen Verdauungssegmenten Magen und Dünndarm sowie des gesamten Verdauungssystems auf molekularer Ebene zu untersuchen. Für die Simulierung der Biofluide wurden Speichel, Magen-, Pankreassaft und Gallenflüssigkeit sowie die Verdauungssegmente basierend auf der menschlichen Physiologie synthetisch hergestellt.[1] Die chemische Speziation wurde mittels zeitaufgelöster laserinduzierter Fluoreszenz-Spektroskopie unter kryogenen Bedingungen (Kryo-TRLFS) bei 153 K untersucht sowie die Ergebnisse mit thermodynamischen Modellierungen verglichen.
Anhand der TRLFS-Experimente kann gezeigt werden, dass die Speziation von Uran überwiegend von den anorganischen Bestandteilen, hauptsächlich Carbonat und zu einem geringeren Anteil Phosphat, dominiert wird. Bei den organischen Komponenten ist lediglich das Protein Mucin bei sauren pH-Werten, wie z. B. im Magen, an der Speziation beteiligt, weshalb die Komplexierung von Mucin mit Uran(VI) genauer betrachtet wurde. Des Weiteren wurden Zellexperimente mit Nierenzellen von Menschen (HEK-293) und Ratten (NRK-52E) in vitro durchgeführt, um den Effekt von Uran auf die Zellen mittels XTT-Assays zu untersuchen. Um den biochemischen Mechanismus auf molekularer Ebene zu verstehen, wurde die Speziation von Uran im Zellkulturmedium ebenfalls mittels Kryo-TRLFS analysiert. Bei der Hauptspezies, welche auf die Zellen einwirkt, handelt es sich um eine Uranylcarbonatverbindung.
Diese Arbeit wird vom Bundesministerium für Bildung und Forschung (BMBF) unter dem Förderkennzeichen 02NUK057A gefördert und ist Teil des Verbundprojekts RADEKOR.
Referenzen:
[1] C. Wilke et al., J. Inorg. Biochem. 2017, 175, 248-258.

  • Poster
    Jahrestagung der Fachgruppe Nuklearchemie 2022, 04.-06.10.2022, Bergisch Gladbach, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34776


Cans production of technetium-99m and technetium-101

Mayordomo, N.; Mausolf, E. J.; Johnstone, E.; Williams, D. L.; Guan, E. Y. Z.; Gary, C. K.; Davis, J.

Abstract

Technetium-99m (99mTc, t1/2 = 6.007 h) has been widely used for radiodiagnostic purposes for decades, and it is still one of the most used radioisotopes worldwide with an estimated 40 million doses consumed annually. Tc-99m can be produced through various nuclear transmutation methods, but commercially speaking, it is generally derived from molybdenum-99 (99Mo, t1/2 = 65.925 h), where the origin of it is dependent upon chemistry and isotopic composition of the target material, e.g., natural or enriched Mo, or enriched 235U targets. However, the production and distribution of 99mTc relies on a complex supply-chain that has proven itself prone to disruptions in years past and was most recently observed during the SARS-CoV-2 pandemic.[1] Ultimately, this leads to delays on diagnoses of patients due to postponed imaging procedures as well as the loss of material and capital.
As a solution to this problem, the deployment of a decentralised network of compact accelerator neutron sources (CANS) for producing 99mTc and 101Tc (t1/2 = 14.22 min) using the (n,𝛾) reaction on Mo-based targetry has been proposed.[2] For example, the use of fusion-driven deuterium-deuterium (D-D) neutron generators for producing both 99mTc and 101Tc has been demonstrated along with their subsequent isolation using a separation tailored for low-specific activity 99Mo targets.[2]
Another under-utilised source of neutrons already being generated in this fashion is during the production of many positron emission tomography (PET) radionuclides in cyclotrons, where parasitic neutrons are liberated from the cyclotron target, e.g., 18O(p,n)18F. The implementation of larger production batches, high yield targetry, and more production runs are all complementary to generating neutrons. From this, the hybridised production of 99mTc and 101Tc concurrently during [18F]FDG has been demonstrated and its feasibility explored.[3]
The aim of the work presented herein is to compare various CANS production modes for 99mTc and 101Tc production in regards to their subsequent applications. Further, it provides potential alternatives for the future production of radiopharmaceuticals, meanwhile meeting the objectives of several Unesco and sustainable development goals.

REFERENCES
[1] K. SADRI, V.R. DABBAGH, M.N. FORGHANI, M. ASADI, R. SADEGUI, Lymphoscintigraphy in the Time of COVID-19: Effect of Molybdenum-99 Shortage on Feasibility of Sentinel Node Mapping, Lymphat. Res. Biol. 19 (2021) 134–140.
[2] E.J. MAUSOLF, E.V. JOHNSTONE, N. MAYORDOMO, D.L. WILLIAMS, E.Y.Z. GUAN, C.K. GARY, Fusion-Based Neutron Generator Production of Tc-99m and Tc-101 : A Prospective Avenue to Technetium Theranostics, Pharmaceuticals. 14 (2021) 1–19.
[3] E.V. JOHNSTONE, E.J. MAUSOLF. Hybridized Production of 18F and 99mTc on a Low-Energy Cyclotron. Internal Document, IFS, LLC (2021).

Keywords: Technetium; Neutron generator; Compact accelerator neutron sources; Radiopharmaceuticals

  • Lecture (Conference) (Online presentation)
    International Conference on Accelerators for Research and Sustainable Development: From Good Practices Towards Socioeconomic Impact, 23.-27.05.2022, Viena, Austria

Permalink: https://www.hzdr.de/publications/Publ-34775


Correlation Between Quantitative PSMA PET Parameters and Clinical Risk Factors in Non-Metastatic Primary Prostate Cancer Patients

Zschaeck, S.; Andela, S. B.; Amthauer, H.; Furth, C.; Rogasch, J. M.; Beck, M.; Hofheinz, F.; Huang, K.

Abstract

Background

PSMA PET is frequently used for staging of prostate cancer patients. Furthermore, there is increasing interest to use PET information for personalized local treatment approaches in surgery and radiotherapy, especially for focal treatment strategies. However, it is not well established which quantitative imaging parameters show highest correlation with clinical and histological tumor aggressiveness.

Methods

This is a retrospective analysis of 135 consecutive patients with non-metastatic prostate cancer and PSMA PET before any treatment. Clinical risk parameters (PSA values, Gleason score and D’Amico risk group) were correlated with quantitative PET parameters maximum standardized uptake value (SUVmax), mean SUV (SUVmean), tumor asphericity (ASP) and PSMA tumor volume (PSMA-TV).

Results

Most of the investigated imaging parameters were highly correlated with each other (correlation coefficients between 0.20 and 0.95). A low to moderate, however significant, correlation of imaging parameters with PSA values (0.19 to 0.45) and with Gleason scores (0.17 to 0.31) was observed for all parameters except ASP which did not show a significant correlation with Gleason score. Receiver operating characteristics for the detection of D’Amico high-risk patients showed poor to fair sensitivity and specificity for all investigated quantitative PSMA PET parameters (Areas under the curve (AUC) between 0.63 and 0.73). Comparison of AUC between quantitative PET parameters by DeLong test showed significant superiority of SUVmax compared to SUVmean for the detection of high-risk patients. None of the investigated imaging parameters significantly outperformed SUVmax.

Conclusion

Our data confirm prior publications with lower number of patients that reported moderate correlations of PSMA PET parameters with clinical risk factors. With the important limitation that Gleason scores were only biopsy-derived in this study, there is no indication that the investigated additional parameters deliver superior information compared to SUVmax.

Keywords: PSMA; prostate specific membrane antigen; positron emission tomography; primary prostate cancer; quantitative PET parameters

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  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-34774


Insights into the Enigmatic TcO₂·xH₂O Structure via Atomistic Simulations

Faria Oliveira, A.; Kuc, A. B.; Heine, T.; Scheinost, A.

Abstract

Technetium is the lightest element without a stable isotope. The β‑emitting ⁹⁹Tc is especially relevant for nuclear waste management due to its long half-life (ca. 2.1×10⁵ years) and relatively high formation yield (≥6%) in ²³⁵U and ²³⁹Pu nuclear reactors. In this context, redox reactions at mineral/water interfaces are crucial for the safety of nuclear waste repositories.

In the absence of complexing agents, Tc exists in water as Tc(VII) and Tc(IV). The former predominates in non-reducing conditions as TcO₄⁻(aq), which is highly mobile in the environment due to its solubility and weak interaction with adsorbents. Studies show that Fe(II) minerals can reduce Tc(VII) to Tc(IV), which is then immobilized by adsorption onto or incorporation into the oxidized Fe mineral and by precipitation as TcO₂·xH₂O. However, even in the simpler case (precipitation) the structure of TcO₂·xH₂O remains controversial.

Lukens et al. [1] demonstrated that, despite being amorphous, TcO₂·xH₂O has a well-defined local structure. Based on EXAFS measurements, they proposed that TcO₂·xH₂O forms linear chains of equally spaced edge-sharing TcO₄(H₂O)₂ octahedra, with terminal H₂O ligands at the apical positions. Vichot et al. [2] obtained similar results but, despite having extracted only one Tc‑Tc distance from the EXAFS, proposed that Tc atoms would be separated by shorter and longer alternating distances as in the monoclinic TcO₂ crystal. More recently, Yalçintaş et al. [3] showed that both models can be fitted equally well to the EXAFS and, thus, the TcO₂·xH₂O structure remained unsolved.

In this work, we use density functional theory (DFT) to investigate the polymeric TcO₂·xH₂O structure. Our calculations reveal that, in contrast to previous models, a zigzag configuration with the terminal H₂O groups at neighboring positions of the octahedra is more likely. The zigzag configuration is energetically more favored and results in a better agreement with the EXAFS measurement.

[1] Lukens et al. (2002), Environ. Sci. Technol. 36, 1124-1129.
[2] Vichot et al. (2002), Radiochim. Acta 90, 575-579.
[3] Yalçintaş et al. (2016), Dalton Trans. 45, 17874-17885.

Keywords: DFT; EXAFS; Technetium

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  • Lecture (Conference) (Online presentation)
    Goldschmidt2022, 10.-15.07.2022, Honolulu, Hawaii, USA

Permalink: https://www.hzdr.de/publications/Publ-34773


Research data: Fano interference between collective modes in cuprate high-Tc superconductors

Chu, H.; Kovalev, S.; Xiao Wang, Z.; Schwarz, L.; Dong, T.; Feng, L.; Haenel, R.; Kim, M.-J.; Phuong Hoang, L.; Honasoge, K.; David Dawson, R.; Putzky, D.; Kim, G.; Puviani, M.; Chen, M.; Awari, N.; Ponomaryov, O.; Ilyakov, I.; Bluschke, M.; Boschini, F.; Zonno, M.; Zhdanovich, S.; Na, M.; Christiani, G.; Logvenov, G.; Jones, D. J.; Damascelli, A.; Minola, M.; Keimer, B.; Manske, D.; Wang, N.; Deinert, J.-C.; Kaiser, S.

Abstract

Research data and metadata that was used in the corresponding publication "Fano interference between collective modes
in cuprate high-Tc superconductors" ( https://doi.org/10.1038/s41467-023-36787-4 ).

Keywords: Terahertz; Higgs spectroscopy; ultrafast; phase-resolved; Superconductivity; cuprates; magnetic fields; doping

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Permalink: https://www.hzdr.de/publications/Publ-34772


Porous Dithiine-Linked Covalent Organic Framework as a Dynamic Platform for Covalent Polysulfide Anchoring in Lithium–Sulfur Battery Cathodes

Haldar, S.; Wang, M.; Bhauriyal, P.; Hazra, A.; Khan, A. H.; Bon, V.; Isaacs, M. A.; de Ankita, L. S.; Boenke, T.; Grothe, J.; Heine, T.; Brunner, E.; Feng, X.; Dong, R.; Schneemann, A.; Kaskel, S.

Abstract

Dithiine linkage formation via a dynamic and self-correcting nucleophilic aromatic substitution reaction enables the de novo synthesis of a porous thianthrene-based two-dimensional covalent organic framework (COF). For the first time, this organo-sulfur moiety is integrated as a structural building block into a crystalline layered COF. The structure of the new material deviates from the typical planar interlayer stacking of the COF to form undulated layers caused by bending along the C-S-C bridge, without loss of aromaticity and crystallinity of the overall COF structure. Comprehensive experimental and theoretical investigations of the COF and a model compound, featuring the thianthrene moiety, suggest partial delocalization of sulfur lone pair electrons over the aromatic backbone of the COF decreasing the band gap and promoting redox activity.
Postsynthetic sulfurization allows for direct covalent attachment of polysulfides to the carbon backbone of the framework to afford a molecular-designed cathode material for lithium-sulfur (Li-S) batteries with a minimized polysulfide shuttle. The fabricated coin cell delivers nearly 77% of the initial capacity even after 500 charge-discharge cycles at 500 mA/g current density. This novel sulfur linkage in COF chemistry is an ideal structural motif for designing model materials for studying advanced electrode materials for Li-S batteries on a molecular level.

Keywords: Aromatic compounds; Covalent organic frameworks; Layers; Lithium; Sulfur

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Permalink: https://www.hzdr.de/publications/Publ-34771


Dataset for Inversion of GISAXS data (3 layers)

Zhdanov, M.; Ganeva, M.; Randolph, L.; Kluge, T.; Hoffmann, N.

Abstract

The dataset consists of 50000 X-ray diffraction patterns simulated by BornAgain [1] software. For each simulation, a multilayer sample model of the following structure was used: air, tantalum oxide, tantalum, copper nitride, silicon dioxide, and substrate. Parameters of air, silicon dioxide, and substrate were kept fixed. Hence, each diffraction pattern is set to depend on the parameters of tantalum oxide, tantalum, and copper nitride layers. For each layer, those are real and complex parts of refractive index, thickness, roughness, Hurst parameter, and correlation length. Each simulation output is stored in an h5py file consisting of 1) diffraction image as a NumPy array of shape [1200, 120]; 2) parameters of a sample as a NumPy array with 18 elements. For further details regarding simulation see https://github.com/maxxxzdn/gisaxs-reconstruction/simulation/simulation.

[1] Pospelov, G., Van Herck, W., Burle, J., Carmona Loaiza, J.M., Durniak, C., Fisher, J., Ganeva, M., Yurov, D., & Wuttke, J. (2020). BornAgain: software for simulating and fitting grazing-incidence small-angle scattering. Journal of Applied Crystallography, 53, 262 - 276.

Keywords: GISAXS; Inverse problems

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Permalink: https://www.hzdr.de/publications/Publ-34770


Dataset for Inversion of GISAXS data (1 layer)

Zhdanov, M.; Ganeva, M.; Randolph, L.; Kluge, T.; Hoffmann, N.

Abstract

The dataset consists of 50000 X-ray diffraction patterns simulated by BornAgain [1] software. For each simulation, a multilayer sample model of the following structure was used: air, tantalum oxide, silicon dioxide, and substrate. Parameters of each layer but tantalum oxide were kept fixed. Hence, each diffraction pattern depends on the parameters of the tantalum oxide layer: real and complex part of refractive index, thickness, roughness, Hurst parameter, and correlation length. Each simulation output is stored in an h5py file consisting of 1) diffraction image as a NumPy array of shape [1024, 512]; 2) sample parameters as a NumPy array with 6 elements. For further details regarding simulation, see https://github.com/maxxxzdn/gisaxs-reconstruction/simulation/simulation.

[1] Pospelov, G., Van Herck, W., Burle, J., Carmona Loaiza, J.M., Durniak, C., Fisher, J., Ganeva, M., Yurov, D., & Wuttke, J. (2020). BornAgain: software for simulating and fitting grazing-incidence small-angle scattering. Journal of Applied Crystallography, 53, 262 - 276.

Keywords: GISAXS; Inverse problems

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Permalink: https://www.hzdr.de/publications/Publ-34769


Palbociclib impairs the proliferative capacity of activated T cells while retaining their cytotoxic efficacy

Arndt, C.; Tunger, A.; Wehner, R.; Rothe, R.; Kourtellari, E.; Luttosch, S.; Hannemann, K.; Koristka, S.; Loureiro, L. R.; Feldmann, A.; Tonn, T.; Link, T.; Kuhlmann, J. D.; Wimberger, P.; Bachmann, M.; Schmitz, M.

Abstract

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor palbociclib is an emerging cancer therapeutic that just recently gained Food and Drug Administration approval for treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor (Her)2-negative breast cancer in combination with the ER degrader fulvestrant. However, CDK4/6 inhibitors are not cancer-specific and may affect also other proliferating cells. Given the importance of T cells in antitumor defense, we studied the influence of palbociclib/fulvestrant on human CD3+ T cells and novel emerging T cell-based cancer immunotherapies. Palbociclib considerably inhibited the proliferation of activated T cells by mediating G0/G1 cell cycle arrest. However, after stopping the drug supply this suppression was fully reversible. In light of combination approaches, we further investigated the effect of palbociclib/fulvestrant on T cell-based immunotherapies by using a CD3-PSCA bispecific antibody or universal chimeric antigen receptor (UniCAR) T cells. Thereby, we observed that palbociclib clearly impaired T cell expansion. This effect resulted in a lower total concentration of interferon-g and tumor necrosis factor, while palbociclib did not inhibit the average cytokine release per cell. In addition, the cytotoxic potential of the redirected T cells was unaffected by palbociclib and fulvestrant. Overall, these novel findings may have implications for the design of treatment modalities combining CDK4/6 inhibition and T cell-based cancer immunotherapeutic strategies.

Keywords: cancer immunotherapy; CDK4/6; palbociclib; fulvestrant; bispecific antibody; CAR T cell; adoptive T therapy

Permalink: https://www.hzdr.de/publications/Publ-34768


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