Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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38996 Publications

Prompt gamma particle imaging

Richter, C.

The lecture will give an overview of the utilization of prompt-gamma (PG) radiation, emitted from the
patient’s body during fractionated particle therapy treatment, for range and treatment verification.
After the nuclear physics basics of the emission of prompt gamma rays have been refreshed, the three
fundamental approaches for PG-based particle range determination will be discussed, which use
either spatial, temporal or spectroscopic information of PG - namely prompt gamma imaging (PGI),
prompt gamma timing (PGT) and prompt gamma spectroscopy (PGS), respectively. Special emphasis
will be on the interpretation of the complex PG data for the distinction of clinically relevant from
irrelevant treatment deviations, necessary for the clinical application of PG for treatment intervention in an online-adaptive PT realization. Results from the evaluation of clinically acquired PGI data will be

  • Lecture (Conference)
    RAPTOR school - loop requirements, 04.-09.09.2022, Ljubljana, Slovenia

Publ.-Id: 35133

Next-generation radiation therapy: Towards near-realtime adaptive proton therapy

Richter, C.

Next-generation radiation therapy: Towards near-realtime adaptive proton therapy

  • Lecture (Conference)
    2nd Meeting Strategic Advisory Board Helmholtz Health, 23.05.2022, Heidelberg, Deutschland

Publ.-Id: 35132

Highlights der Medizinphysik

Richter, C.

Highlights in der Medizinphysik

  • Open Access Logo Lecture (Conference)
    100 Jahre Strahlentherapie in Dresden, 21.06.2022, Dresden, Deutschland

Publ.-Id: 35131

Dual-Energy CT in Radiation Oncology

Richter, C.; Wohlfahrt, P.

In radiation oncology, CT imaging is of crucial importance for consistent and accurate delineation of target and organ-at-risk structures as well as for highly precise treatment planning and prediction of the deposited dose. Even though the potential benefit of dual-energy CT for those purposes was identified early, its implementation in clinical practice is still in an early stage. Here, we want to give an overview of current and potential future applications of dual-energy CT in the field of radiation oncology. Since the next generation of X-ray computed tomography with a photon-counting detector technology is rising at the horizon, we also want to give an outlook on radiotherapeutic applications that will benefit or even become possible for the first time with this technological evolution.

  • Book chapter
    Hatem Alkadhi, André Euler, David Maintz, Dushyant Sahani: Spectral Imaging, Switzerland: Springer, 2022, 978-3-030-96285-2, 333-346
    DOI: 10.1007/978-3-030-96285-2

Publ.-Id: 35130

The Chemical Journey of Europium(III) through Winter Rye (Secale cereale L.) – Understanding through Mass Spectrometry and Chemical Microscopy

Stadler, J.; Vogel, M.; Steudtner, R.; Drobot, B.; Kogiomtzidis, A.; Weiss, M.; Walther, C.

A combination of biochemical preparation methods with microscopic, spectroscopic, and mass spectrometric analysis techniques as contemplating state of the art application, was used for direct visualization, localization, and chemical identification of europium in plants. This works illustrates the chemical journey of europium (Eu(III)) through winter rye (Secale cereale L.), providing insight into the possibilities of speciation for Rare Earth Elements (REE) and trivalent f-elements. Kinetic experiments of contaminated plants show a maximum europium concentration in Secale cereale L. after four days. Transport of the element through the vascular bundle was confirmed with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDS). For chemical speciation, plants were grown in a liquid nutrition medium, whereby Eu(III) species distribution could be measured by mass spectrometry and luminescence measurements. Both techniques confirm the occurrence of Eu malate species in the nutrition medium, and further analysis of the plant was performed. Luminescence results indicate a change in Eu(III) species distribution from root tip to plant leaves. Microscopic analysis show at least three different Eu(III) species with potential binding to organic and inorganic phosphate groups and a Eu(III) protein complex. With plant root extraction, further europium species could be identified by using Electrospray Ionization Mass Spectrometry (ESI MS). Complexation with malate, citrate, a combined malate-citrate ligand, and aspartate was confirmed mostly in a 1:1 stoichiometry (Eu:ligand). The combination of the used analytical techniques opens new possibilities in direct species analysis, especially regarding to the understanding of rare earth elements (REE) uptake in plants. This work provides a contribution in better understanding of plant mechanisms of the f-elements and their species uptake.

Keywords: Rare earth elements; plant uptake; species analysis; europium; imaging

Publ.-Id: 35129

Personalised radiation therapy taking both the tumour and patient into consideration

Overgaard, J.; Aznar, M. C.; Bacchus, C.; Coppes, R. P.; Deutsch, E.; Georg, D.; Haustermans, K.; Hoskin, P.; Krause, M.; Lartigau, E. F.; Lee, A. W. M.; Steffen Löck J, B. V. O.; Thwaites, D. I.; van der Kogel, A. J.; van der Heide, U. A.; Valentini, V.; Baumann, M.

A look through almost 2000 abstracts submitted for the upcom-
ing ESTRO 2022 meeting together with a glance back on the 2021
papers published in Radiotherapy and Oncology gives one a good
impression of the (current) key focus areas in radiation oncology:
Almost all of this work relates to optimal delivery of radiation ther-
apy in terms of technology, quality assurance and morbidity reduc-
ing approaches. Thus, at present the research questions considered
as most relevant for radiotherapy of e.g. lung and oesophageal can-
cer are not related to tumour control, but to the late risk of cardiac
disease in the patients who are lucky to survive their cancer long
enough to develop such problems [1]. The same scenario is found
in the patient cohort that constitutes the largest indication for
radiotherapy in Europe: women with early breast cancer [2]. In
these examples, and in many other situations where radiotherapy
is applied with a curative intent, less focus has currently been
given to the aim or indication of the treatment, namely the control
of loco-regional malignant disease. Of course, since Holthusen’s
seminal paper in 1936 [3] the overall aim of radiotherapy, as stated
over and over again by all teachers in the field (including the
authors of this editorial), is uncomplicated tumour control, i.e.
loco-regional tumour control without severe normal tissue damage
(therapeutic ratio). This implies that rigorous study of the effects of
radiotherapy on normal, non-tumour, tissues is an absolute necessity. Yet, the prescription of radiotherapy in clinical practice is
done to kill tumour cells for local and loco-regional control. If the
effects of radiotherapy on tumours are shifting out of focus, it
might be taken for granted that the indication, dose, fractionation,
and potential multidisciplinary interactions in this field are fully
understood, and what remains is the fine tuning of the associated
risk of morbidity.

Publ.-Id: 35128

Ion Microprobe analysis of wear processes in ta-C coatings and contact areas on the counter bodies

Munnik, F.; Lorenz, L.; Härtwig, F.; Krause, M.

Solid lubricants, like ta-C (hydrogen-free tetrahedral amorphous carbon) coatings, are an active area of research to replace liquid lubricants. This substitution is important because of the negative environmental impact and high material consumption of liquid lubricants. The influence of soft metal counter bodies on the unlubricated friction behaviour of hydrogen-free carbon coatings has mostly been studied for doped a-C coatings so far. All these studies show that low friction and wear can only be achieved if a tribolayer is formed to protect the contact. Even with a formed tribolayer, its composition is crucial for the frictional behaviour, making the investigation of this composition essential. A study currently underway aims to identify friction-induced surface changes like material loss of the coating, material transfer between the counter body and the coating, or the formation of a tribolayer.
The current work presents Ion Beam Analysis methods to deliver laterally and depth-resolved element analysis of the wear track on the coating and the contact area of the counter bodies (CB). In a first test, a ta-C coating has been subjected to pin-on-disk tests with various metallic and ceramic CBs. He and H ion microbeams have been used to scan over the tracks and the contact areas of the CBs. Both RBS and PIXE have been used and first results are presented. It is shown that, in this case, RBS yields the more useful information. Both, a 2 MeV He ion beam and a 3 MeV H ion beam provide valuable results. The advantages of each type of ion beam depend on the sample and the information needed. As shown in this work, RBS with a 2 MeV He ion beam is useful to determine the transfer layer of a (soft) metal CB to the ta-C coating, whereas 3 MeV H RBS can be used to determine the presence of C and O on the CB because of the increased non-Rutherford cross-sections for these elements.

Related publications

  • Poster
    18th International Conference on Nuclear Microprobe Technology and Applications, 11.-16.09.2022, Ljubljana, Slovenia

Publ.-Id: 35127

In vivo assessment of tissue-specific radiological parameters with intra- and inter-patient variation using dual-energy computed tomography

Peters, N.; Kieslich, A.; Wohlfahrt, P.; Hofmann, C.; Richter, C.

Purpose/objective: Experimental in vivo determination of radiological tissue parameters of organs in the
head and pelvis within a large patient cohort, expanding on the current standard human tissue database
summarized in ICRU46.
Material/methods: Relative electron density (RED), effective atomic number (EAN) and stopping-power
ratio (SPR) were obtained from clinical dual-energy CT scans using a clinically validated DirectSPR imple-
mentation and organ segmentations of 107 brain-tumor (brain, brainstem, spinal cord, chiasm, optical
nerve, lens) and 120 pelvic cancer patients (prostate, kidney, liver, bladder). The impact of contamination
by surrounding tissues on the tissue parameters was reduced with a dedicated contour adaption routine.
Tissue parameters were characterized regarding the cohort mean value as well as the variation within
each patient (2rintra) and between patients (2rinter ). For the brain, age-dependent differences were deter-
Results: For 10 organs, including 4 structures not listed in ICRU46, the mean RED, EAN and SPR as well as
their respective intra- and inter-patient variation were determined. SPR intra-patient variation was
higher than 1.3% (1.3–4.6%) in all organs and always exceeded the inter-patient variation of the organ
mean SPR (0.6–2.1%). For the brain, a significant SPR variation between pediatric and non-pediatric
patients was determined.
Conclusion: Radiological tissue parameters in the head and pelvis were characterized in vivo for a large
patient cohort using dual-energy CT. This reassesses parts of the current standard database defined in
ICRU46, furthermore complementing the data described in literature by smaller substructures in the
brain as well as by the quantification of organ-specific inter- and intra-patient variation.

Keywords: Proton therapy; Dual-energy computed tomography; DECT; Tissue parameters

Publ.-Id: 35126

Physics and Imaging in Radiation Oncology

Peters, N.; Muren, L. P.

cement compared to conventional radiotherapy due to the finite
range of protons in the patient. To ensure target coverage, additional
healthy tissue around the target volume is irradiated in clinical routine.
Advancements in both patient imaging and treatment planning there-
fore aim to reduce these clinical safety margins. However, any reduction
of the overall safety margin also reduces the possibility to compensate
for uncertainty sources that are not explicitly considered in the uncer-
tainty estimation and therefore comes with a risk of decreased target
coverage [1]. At the same time, an appropriate technique for combining
and considering the different uncertainties in the treatment planning
process is necessary as not to dilute technical advancements.

Publ.-Id: 35125

Randomisierte Studie zum Vergleich von Nebenwirkungen nach Protonen- versus Photonen- Strahlentherapie bei Patienten mit fortgeschrittenem nichtkleinzelligen Bronchialkarzinom

Troost, E. G. C.; Zschaeck, S.; Bütof, R.; Czekalla, M.; Richter, C.; Stützer, K.; Krause, M.; Baumann, M.

Bronchialkarzinome sind in Deutschland
die dritthäufigste Tumorerkrankung. Trotz
erheblicher therapeutischer Fortschritte ist
die Prognose der Lungentumoren nach
wie vor ungünstig, die relative 5-Jahres-
Überlebensrate nach Diagnose eines Bron-
chialkarzinoms beträgt lediglich 16 % [3].
Hinsichtlich der Tumorart werden nicht-
kleinzellige (NSCLC) und kleinzellige Bron-
chialkarzinome unterschieden.
Bei fortgeschrittenen NSCLC besteht
die Standardtherapie aus einer gleichzei-
tig durchgeführten Radiochemotherapie,
gefolgt von einer Immuntherapie. In
Metaanalysen konnte die Überlegenheit
der simultanen Radiochemotherapie ge-
genüber einem sequenziellen Vorgehen
gezeigt werden.

Publ.-Id: 35124

The force balance of hydrogen bubbles growing and oscillating on a microelectrode

Hossain, S. S.; Bashkatov, A.; Yang, X.; Mutschke, G.; Eckert, K.

Hydrogen evolution in acidic aqueous electrolytes was recently found to be characterized by a
carpet of microbubbles covering the microelectrode and feeding the growth of the main bubbles by
coalescence. Besides this, oscillatory behavior of the main bubbles was observed prior to departure.
Extending earlier studies, this work delivers the forces acting on the main bubble more accurately
by taking into account further geometric and electrochemical details measured during experiments.
Combining simulation work and measurements makes it possible to confirm the role of an attractive
electrical (Coulomb) force caused by the adsorption of hydrogen ions at the bubble interface and to
obtain a better understanding of the bubble dynamics observed.

Keywords: electrolysis; gas evolution; hydrogen production; force balance; Marangoni effect; adsorption at interfaces; numerical simulation; particle tracking velocimetry


  • Secondary publication expected from 26.09.2023

Publ.-Id: 35123

Vorstoß in die Terahertz-Lücke

Deinert, J.-C.; Kovalev, S.; Gensch, M.

Der Terahertz-Frequenzbereich umfasst ein technisch wenig erschlossenes Grenzgebiet im elektromagnetischen Spektrum. Er ist aber besonders interessant, weil er viele Eigenfrequenzen verschiedener, komplexer Quantenphänomene enthält. Dafür stehen neuerdings intensive Terahertz-Pulse aus spezialisierten Elektronenbeschleunigerquellen zur Verfügung. Sie bieten nun eine einzigartige Möglichkeit, solch fundamentale Quantenprozesse im Nichtgleichgewicht zu untersuchen

Keywords: Terahertz; Elektronenbeschleuniger; Ladungsträgerdynamik; Lichtquellen; Ultrakurzzeitphysik

Related publications

Publ.-Id: 35122

A study on rare-earth Laves phases for magnetocaloric liquefaction of hydrogen

Liu, W.; Bykov, E.; Taskaev, S.; Bogush, M.; Khovaylo, V.; Fortunato, N.; Aubert, A.; Zhang, H.; Gottschall, T.; Wosnitza, J.; Scheibel, F.; Skokov, K.; Gutfleisch, O.

We are witnessing a great transition towards a society powered by renewable energies to meet the ever-stringent climate target. Hydrogen, as an energy carrier, will play a key role in building a climate-neutral society. Although liquid hydrogen is essential for hydrogen storage and transportation, liquefying hydrogen is costly with the conventional methods based on Joule-Thomas effect. As an emerging technology which is potentially more efficient, magnetocaloric hydrogen liquefaction can be a “game-changer”. In this work, we have investigated the rare-earth-based Laves phases RAl and RNi2 for magnetocaloric hydrogen liquefaction. We have noticed an unaddressed feature that the magnetocaloric effect of second-order magnetocaloric materials can become “giant” near the hydrogen boiling point. This feature indicates strong correlations, down to the boiling point of hydrogen, among the three important quantities of the magnetocaloric effect: the maximum magnetic entropy change ΔSmax m, the maximum adiabatic temperature change ΔTmax ad , and the Curie temperature TC. Via a comprehensive literature review, we interpret the correlations for a rare-earth intermetallic series as two trends: (1) ΔSmax m increases with decreasing TC; (2) ΔTmax ad decreases near room temperature with decreasing TC but increases at cryogenic temperatures. Moreover, we have developed a mean-field approach to describe these two trends theoretically. The dependence of ΔSmax m and ΔTmax ad on TC revealed in this work helps researchers quickly anticipate the magnetocaloric performance of rare-earth-based compounds, guiding material design and accelerating the discoveries of magnetocaloric materials for hydrogen liquefaction.


Publ.-Id: 35121

Enzymological characterization of ⁶⁴Cu-labeled neprilysin substrates and their application for modulating the renal clearance of targeted radiopharmaceuticals

Brandt, F.; Ullrich, M.; Wodtke, J.; Kopka, K.; Bachmann, M.; Löser, R.; Pietzsch, J.; Pietzsch, H.-J.; Wodtke, R.

The applicability of radioligands for targeted endoradionuclide therapy is limited due to radiation-induced deleterious effects to healthy tissues. This applies in particular to the kidneys as primary organs of elimination, which requires dosimetric estimates to justify internal radionuclide therapy. In this context, the targeting of enzymes of the renal brush border membrane by cleavable linkers between target molecule and radiolabel that permit the formation of fast eliminating radionuclide-carrying cleavage fragments gains increasing interest. Herein, we synthesized a small library of ⁶⁴Cu-labeled cleavable linkers and quantified their substrate potentials toward neprilysin (NEP), a highly abundant peptidase at the renal brush border membrane. This allowed for the derivation of structure-activity relationships and selected cleavable linkers were attached to the somatostatin receptor subtype 2 ligand [Tyr³]octreotate. Subsequent radiopharmacological characterization revealed that a substrate-based targeting of NEP in the kidneys with small molecules or peptides entails a certain degree of premature cleavage in the blood circulation by soluble and endothelium-derived NEP. However, for a tissue-specific targeting of NEP in the kidneys, the additional targeting of albumin in the blood by albumin-binding moieties is highlighted.


  • Secondary publication expected from 03.01.2024

Publ.-Id: 35120

Combined Systemic Drug Treatment with Proton Therapy: Investigations on Patient-Derived Organoids

Naumann, M.; Czempiel, T.; Jana Lößner, A.; Pape, K.; Beyreuther, E.; Löck, S.; Drukewitz, S.; Hennig, A.; von Neubeck, C.; Klink, B.; Krause, M.; William, D.; Stange, D. E.; Bütof, R.; Dietrich, A.

To optimize neoadjuvant radiochemotherapy of pancreatic ductal adenocarcinoma (PDAC),
the value of new irradiation modalities such as proton therapy needs to be investigated in relevant
preclinical models. We studied individual treatment responses to RCT using patient-derived PDAC
organoids (PDO). Four PDO lines were treated with gemcitabine, 5-fluorouracile (5FU), photon and
proton irradiation and combined RCT. Therapy response was subsequently measured via viability
assays. In addition, treatment-naive PDOs were characterized via whole exome sequencing and
tumorigenicity was investigated in NMRI Foxn1nu/nu mice. We found a mutational pattern con-
taining common mutations associated with PDAC within the PDOs. Although we could unravel
potential complications of the viability assay for PDOs in radiobiology, distinct synergistic effects
of gemcitabine and 5FU with proton irradiation were observed in two PDO lines that may lead to further mechanistical studies. We could demonstrate that PDOs are a powerful tool for translational
proton radiation research.

Keywords: patient-derived organoid; PDAC; pancreatic cancer; radiochemotherapy; 3D cell culture; proton irradiation; translational radiooncology

Publ.-Id: 35119

European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus recommendations on patient selection and dose and fractionation for external beam radiotherapy in early breast cancer

Meattini, I.; Becherini, C.; Boersma, L.; Kaidar-Person, O.; Nader Marta, G.; Montero, A.; Vrou Offersen, B.; Aznar, M. C.; Belka, C.; Murray Brunt, A.; Dicuonzo, S.; Franco, P.; Krause, M.; Mairead Mackenzie, T. M.; Marrazzo, L.; Ratosa, I.; Scholten, A.; Senkus, E.; Stobart, H.; Poortmans, P.; Coles, C. E.

High-quality randomised clinical trials testing moderately fractionated breast radiotherapy have clearly shown that
local control and survival is at least as effective as with 2 Gy daily fractions with similar or reduced normal tissue
toxicity. Fewer treatment visits are welcomed by patients and their families, and reduced fractions produce substantial
savings for health-care systems. Implementation of hypofractionation, however, has moved at a slow pace. The
oncology community have now reached an inflection point created by new evidence from the FAST-Forward five-
fraction randomised trial and catalysed by the need for the global radiation oncology community to unite during the
COVID-19 pandemic and rapidly rethink hypofractionation implementation. The aim of this paper is to support
equity of access for all patients to receive evidence-based breast external beam radiotherapy and to facilitate the
translation of new evidence into routine daily practice. The results from this European Society for Radiotherapy and
Oncology Advisory Committee in Radiation Oncology Practice consensus state that moderately hypofractionated
radiotherapy can be offered to any patient for whole breast, chest wall (with or without reconstruction), and nodal
volumes. Ultrafractionation (five fractions) can also be offered for non-nodal breast or chest wall (without
reconstruction) radiotherapy either as standard of care or within a randomised trial or prospective cohort. The
consensus is timely; not only is it a pragmatic framework for radiation oncologists, but it provides a measured
proposal for the path forward to influence policy makers and empower patients to ensure equity of access to evidence-
based radiotherapy.


Publ.-Id: 35118

Biomarker signatures for primary radiochemotherapy of locally advanced HNSCC – Hypothesis generation on a multicentre cohort of the DKTK-ROG

Löck, S.; Linge, A.; Lohaus, F.; Ebert, N.; Gudziol, V.; Nowak, A.; Tinhofer, I.; Kalinauskaite, G.; Guberina, M.; Stuschke, M.; Balermpas, P.; von der Grün, J.; Grosu, A.-L.; Debus, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; De-Colle, C.; Zips, D.; Baretton, G. B.; Krause, M.; Baumann, M.

Purpose: To develop prognostic biomarker signatures for patients with locally advanced head and neck
squamous cell carcinoma (HNSCC) treated by primary radiochemotherapy (RCTx) based on previously
published molecular analyses of the retrospective biomarker study of the German Cancer Consortium
– Radiation Oncology Group (DKTK-ROG).

Keywords: HNSCC; Biomarkers; Primary radiochemotherapy; Validation; Signature

Publ.-Id: 35117

Clinical necessity of multi-image based (4DMIB) optimization for targets affected by respiratory motion and treated with scanned particle therapy – A comprehensive review

Knopf, A.-C.; Czerska, K.; Fracchiolla, F.; Graeff, C.; Molinelli, S.; Rinaldi, I.; Rucincki, A.; Sterpin, E.; Stützer, K.; Trnkova, P.; Zhang, Y.; Chang, J. Y.; Giap, H.; Liu, W.; Schild, S. E.; Simone Ii, C. B.; Lomax, A. J.; Meijers, A.

4D multi-image-based (4DMIB) optimization is a form of robust optimization where different uncertainty
scenarios, due to anatomy variations, are considered via multiple image sets (e.g., 4DCT). In this review,
we focused on providing an overview of different 4DMIB optimization implementations, introduced var-
ious frameworks to evaluate the robustness of scanned particle therapy affected by breathing motion and
summarized the existing evidence on the necessity of using 4DMIB optimization clinically. Expected
potential benefits of 4DMIB optimization include more robust and/or interplay-effect-resistant doses for
the target volume and organs-at-risk for indications affected by anatomical variations (e.g., breathing,
peristalsis, etc.). Although considerable literature is available on the research and technical aspects of
4DMIB, clinical studies are rare and often contain methodological limitations, such as, limited patient
number, motion amplitude, motion and delivery time structure considerations, number of repeat CTs,
etc. Therefore, the data are not conclusive. In addition, multiple studies have found that robust 3D opti-
mized plans result in dose distributions within the set clinical tolerances and, therefore, are suitable for a
treatment of moving targets with scanned particle therapy. We, therefore, consider the clinical necessity
of 4DMIB optimization, when treating moving targets with scanned particle therapy, as still to be

Keywords: Proton therapy; 4D optimization; Multi-image-based optimization; Motion management

Publ.-Id: 35116

Integration of p16/HPV DNA Status with a 24-miRNA-Defined Molecular Phenotype Improves Clinically Relevant Stratification of Head and Neck Cancer Patients

Hess, J.; Unger, K.; Maihoefer, C.; Schüttrumpf, L.; Weber, P.; Marschner, S.; Wintergerst, L.; Pflugradt, U.; Baumeister, P.; Walch, A.; Woischke, C.; Kirchner, T.; Werner, M.; Sörensen, K.; Baumann, M.; Tinhofer, I.; Combs, S. E.; Debus, J.; Schäfer, H.; Krause, M.; Linge, A.; von der Grün, J.; Stuschke, M.; Zips, D.; Canis, M.; Lauber, K.; Ganswindt, U.; Henke, M.; Zitzelsberger, H.; Belka, C.

Human papillomavirus (HPV)-driven head and neck squamous cell carcinomas (HNSCC)
generally have a more favourable prognosis. We hypothesized that HPV-associated HNSCC may
be identified by an miRNA-signature according to their specific molecular pathogenesis, and be
characterized by a unique transcriptome compared to HPV-negative HNSCC. We performed miRNA
expression profiling of two p16/HPV DNA characterized HNSCC cohorts of patients treated by
adjuvant radio(chemo)therapy (multicentre DKTK-ROG n = 128, single-centre LMU-KKG n = 101).
A linear model predicting HPV status built in DKTK-ROG using lasso-regression was tested in
LMU-KKG. LMU-KKG tumours (n = 30) were transcriptome profiled for differential gene expression
and miRNA-integration. A 24-miRNA signature predicted HPV-status with 94.53% accuracy (AUC:
0.99) in DKTK-ROG, and 86.14% (AUC: 0.86) in LMU-KKG. The prognostic values of 24-miRNA-
and p16/HPV DNA status were comparable. Combining p16/HPV DNA and 24-miRNA status
allowed patient sub-stratification and identification of an HPV-associated patient subgroup with
impaired overall survival. HPV-positive tumours showed downregulated MAPK, Estrogen, EGFR,
TGFbeta, WNT signaling activity. miRNA-mRNA integration revealed HPV-specific signaling pathway
regulation, including PD−L1 expression/PD−1 checkpoint pathway in cancer in HPV-associated HNSCC.
Integration of clinically established p16/HPV DNA with 24-miRNA signature status improved
clinically relevant risk stratification, which might be considered for future clinical decision-making
with respect to treatment de-escalation in HPV-associated HNSCC.

Keywords: head and neck cancer; HNSCC; HPV; miRNA; signature; prediction; prognosis; mRNA; interaction; signaling pathways

Publ.-Id: 35115

Multiphase CFD for Nuclear Safety Research

Lucas, D.

While according to the state of the art safety analyses related to nuclear reactor thermal hydraulics are done using system codes, CFD becomes more and more important as a tool to support such analyses. Often multiphase flows are involved in the flow situations that have to be considered. For medium and large scales, as they are typical in nuclear reactor safety research, the Euler-Euler (E-E) approach is most suited and most frequently used. However, E-E-CFD is not yet mature. A consolidation of closure models is required to enable reliable predictions. The baseline model concept is a promising way to reach such a consolidation. A baseline model for poly-disperse bubbly flows is established and implemented in the OpenSource CFD package OpenFOAM (Foundation release). The sustainable development requires quality insurance and continuous maintenance of the corresponding OpenFOAM-add-ons which is enabled in the GitLab environement. An automated workflow helps efficiently to support the step-by-step improvement of the baseline model. The lecture presents the baseline model conceptand the general strategy for its further development. This is illustrated by the example of the baseline model for poly-disperse flows. Advantages as well as challenges related to the use of Open Source software in NRS are discussed.

Keywords: multiphase CFD; Euler-Euler model; OpenFOAM

  • Invited lecture (Conferences) (Online presentation)
    13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation, and Safety (NUTHOS-13), 06.-08.09.2022, Hsinchu, Taiwan

Publ.-Id: 35114

Integration of radiation oncology teaching in medical studies by German medical faculties due to the new licensing regulations

Dapper, H.; Belka, C.; Bock, F.; Budach, V.; Budach, W.; Christiansen, H.; Debus, J.; Distel, L.; Dunst, J.; Eckert, F.; Eich, H.; Eicheler, W.; Engenhart-Cabillic, R.; Fietkau, R.; Fleischmann, D. F.; Frerker, B.; Giordano, F. A.; Grosu, A. L.; Herfarth, K.; Hildebrandt, G.; Kaul, D.; Kölbl, O.; Krause, M.; Krug, D.; Martin, D.; Matuschek, C.; Medenwald, D.; Nicolay, N. H.; Niewald, M.; Oertel, M.; Petersen, C.; Pohl, F.; Raabe, A.; Rödel, C.; Rübe, C.; Schmalz, C.; Schmeel, L. C.; Steinmann, D.; Stüben, G.; Thamm, R.; Vordermark, D.; Vorwerk, H.; Wiegel, T.; Zips, D.; Combs, S. E.

The new Medical Licensing Regulations 2025 (Ärztliche Approbationsordnung, ÄApprO) will soon be passed by the Federal Council (Bundesrat) and will be implemented step by step by the individual faculties in the coming months. The further development of medical studies essentially involves an orientation from fact-based to competence-based learning and focuses on practical, longitudinal and interdisciplinary training. Radiation oncology and radiation therapy are important components of therapeutic oncology and are of great importance for public health, both clinically and epidemiologically, and therefore should be given appropriate attention in medical education. This report is based on a recent survey on the current state of radiation therapy teaching at university hospitals in Germany as well as the contents of the National Competence Based Learning Objectives Catalogue for Medicine 2.0 (Nationaler Kompetenzbasierter Lernzielkatalog Medizin 2.0, NKLM) and the closely related Subject Catalogue (Gegenstandskatalog, GK) of the Institute for Medical and Pharmaceutical Examination Questions (Institut für Medizinische und Pharmazeutische Prüfungsfragen, IMPP). The current recommendations of the German Society for Radiation Oncology (Deutsche Gesellschaft für Radioonkologie, DEGRO) regarding topics, scope and rationale for the establishment of radiation oncology teaching at the respective faculties are
also included.

Keywords: Radiation oncology teaching; Medical studies; New licensing regulations

Publ.-Id: 35113

Targeting of p21-Activated Kinase 4 Radiosensitizes Glioblastoma Cells via Impaired DNA Repair

Blankenstein, L. J.; Cordes, N.; Kunz-Schughart, L. A.; Vehlow, A.

Glioblastoma is a devastating malignant disease with poor patient overall survival. Strong invasiveness and resistance to radiochemotherapy have challenged the identification of molecular targets that can finally improve treatment outcomes. This study evaluates the influence of all six known p21-activated kinase (PAK) protein family members on the invasion capacity and radioresponse of glioblastoma cells by employing a siRNA-based screen. In a panel of human glioblastoma cell models, we identified PAK4 as the main PAK isoform regulating invasion and clonogenic survival upon irradiation and demonstrated the radiosensitizing potential of PAK4 inhibition. Mechanistically, we show that PAK4 depletion and pharmacological inhibition enhanced the number of irradiation- induced DNA double-strand breaks and reduced the expression levels of various DNA repair proteins.
In conclusion, our data suggest PAK4 as a putative target for radiosensitization and impairing DNA repair in glioblastoma, deserving further scrutiny in extended combinatorial treatment testing.

Keywords: glioblastoma; p21-activated kinase 4; radiosensitivity; DNA repair

Publ.-Id: 35112

Efficient Production of the PET radionuclide 133La for Theranostic Purposes in Targeted Alpha Therapy using the 134Ba(p,2n)133La Reaction

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Targeted Alpha Therapy is a research field of highest interest in specialized radionuclide therapy. Over the last decades, several alpha-emitting radionuclides have entered and left research topics towards their clinical translation. Especially, 225Ac provides all necessary physical and chemical properties for a successful clinical application, which has already been shown by [225Ac]Ac PSMA 617. While PSMA 617 carries the DOTA as the complexing agent, the chelator macropa as macrocyclic alternative provides even more beneficial properties regarding labeling and complex stability in vivo. Lanthanum-133 is an excellent positron-emitting diagnostic lanthanide to radiolabel macropa-functionalized therapeutics, since 133La forms a perfect matched theranostic pair of radionuclides with the therapeutic radionuclide actinium-225 which itself can optimally be complexed by macropa as well. 133La was thus produced by cyclotron-based proton irradiation of an enriched 134Ba target. The target (30 mg of [134Ba]BaCO3) was irradiated for 60 min at 22 MeV and 10-15 µA beam current. Irradiation side products in the raw target solution were identified and quantified: 135La (0.4%), 135mBa (0.03%), 133mBa (0.01%) and 133Ba (0.0004%). The subsequent work-up and anion-exchange-based product purification process took approx. 30 min and led to a total amount of (1.2 – 1.8) GBq (decay-corrected to EOB) of 133La, formulated as [133La]LaCl3. After complete decay of 133La, a remainder of ca. 4 kBq of long-lived 133Ba per 100 MBq of 133La was detected and rated as uncritical regarding personal dose and waste management. Subsequent radiolabeling was successfully performed with previously published macropa-derived PSMA inhibitors at a micromolar range (quantitative labeling at 1 µM) and evaluated by radio-TLC and radio-HPLC analyses. The scale up to radioactivity amounts that are needed for clinical application purposes would be easy to achieve by increasing target mass, beam current and/or irradiation time to produce 133La of high radionuclide purity (>99.5%) regarding labeling properties and side products.

Keywords: macropa; lanthanum-133; actinium-225; PET; targeted alpha therapy; theranostics

Publ.-Id: 35111

Fallstudie Kühlgeräterecycling

Heibeck, M.; Mütze, T.

Die Fallstudie behandelt einen großtechnischen Recyclingversuch von 100 Kühlgeräten aus dem Haushaltsbereich in einer gewerblichen Erstbehandlungsanlage. Neben der Beobachtung von Be-handlungsschritten wie z. B. der Kompressordemontage wurden die Produktfraktionen Eisen, Nichteisen und Kunststoffe für drei Kühlgerätegruppen näher analysiert. Dabei wurde ein besonde-rer Fokus auf die Analyse von Restverbunden gelegt. Die Versuchsergebnisse ermöglichen eine Unterscheidung zwischen Restverbunden, welche im Prozess gebildet wurden, und anderen, die durch den konstruktiven Aufbau bedingt sind. Dadurch können Potenziale für ein recyclinggerech-teres Design von Kühlgeräten und Herausforderungen bei der Aufschlusszerkleinerung gezeigt werden. Außerdem können beispielsweise Leiterplatten für die Demontage leichter zugänglich an-geordnet werden und Kompressoren eine einfacher und schneller lösbare Befestigung haben. Zu-dem kann ein Auslassventil beim verlustfreien Trockenlegen des Kältekreislaufes helfen.

Keywords: WEEE Erstbehandlung; Schadstoffentfrachtung; mechanische Aufbereitung; Zerkleinerung; Aufschlussgrad

  • Lecture (Conference)
    Recy & DepoTech-Konferenz 2022, 09.-11.11.2022, Leoben, Österreich

Publ.-Id: 35110

THz sources: from semiconductor antennas to relativistic electrons

Helm, M.

I will discuss some developments related to two types of THz sources: on the one hand photoconductive antennas, including recent results using the material germanium, and on the other hand I will give an overview on the accelerator based coherent infrared and THz sources operating at HZDR, and discuss plans for a successor facility.

Keywords: terahertz; photoconductive antenna; free electron laser

Related publications

  • Invited lecture (Conferences)
    47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz) 2022, 28.08.-02.09.2022, Delft, The Netherlands

Publ.-Id: 35109

Experimental comparison of Prompt Gamma-Ray Imaging and Spectroscopy under Equalized Conditions Using a Calibrated Head Phantom

Hueso-González, F.; Berthold, J.; Wohlfahrt, P.; Bortfeld, T.; Khamfongkhruea, C.; Tattenberg, S.; Zarifi, M.; Verburg, J.; Richter, C.

First studies on range verification in proton therapy using prompt gamma-ray spectroscopy (PGS) or imaging (PGI) have been recently conducted with patients. To benchmark the performance of each method, we designed a multi-center experiment between Massachusetts General Hospital and OncoRay with a shared anthropomorphic head phantom irradiated under equalized conditions. The treatment plan was delivered at clinical beam currents and doses in the respective proton therapy hospitals. Two gantry beam angles were used: horizontal and oblique (270° and 350°). Each field contained the same spot positions and energies as well as target volume in both institutions. The experimentally measured range was compared against the ground truth based on the reference stopping-power
map of the phantom. The absolute range error of PGS or PGI was 2.4 mm or -0.5 mm for the horizontal field and 1.3 mm or 2.4 mm for the oblique one, respectively. The ability to detect relative range deviations was assessed by introducing 2 mm and 5 mm plastic slabs on the ventral half of the horizontal field. The measured range shifts were 1.8 mm or 4.8 mm for PGS, and 2.0 mm or 4.2 mm for PGI, respectively. The designed set of experiments represents the first systematic comparison of prompt gamma-ray systems for proton range verification across different institutions using a ground-truth head phantom as reference, and effectively proposes a standard testing platform for benchmarking future proton range verification prototypes in reproducible conditions.

Keywords: proton therapy; prompt gamma-ray; range verification

  • Lecture (Conference)
    2022 IEEE Nuclear Science Symposium and Medical Imaging Conference, 05.-12.11.2022, Milano, Italia

Publ.-Id: 35108

Study on the degradation process of semiconductor photocathodes in particle accelerators

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

The quality of the photocathodes is critical for the stable operation of the electron sources of the accelerator-based light sources (for example X-ray FEL at DESY [1], THz at ELBE [2], etc). In this field, high quantum efficiency (QE) and long operation lifetime are the most important parameters for the ideal photocathode materials. Cs2Te photocathodes have been successfully applied in the e- guns at DESY and in the superconducting RF gun at HZDR. Recently GaN as a new photocathode candidate has been paid more and more attention because of its high QE and robustness. However, even under the extremly high vacuum environment, photocathodes lose QE slowly and change the QE distribution during the operation. In this contribution, we will present the surface study on the Cs2Te and GaN photocathodes, including the QE evolution during operation (see Fig. 1) and the XPS analysis of the 'used' photocathodes (see Fig. 2). Several possible reasons leading degradation of those photocathodes might be: 1. rest gases during operation react with the sensitive alkali-rich surface; 2. the low energy ions, ionized rest gas molecules by the electrons, reach the cathode surface and react with the surface.

Related publications

  • Lecture (Conference)
    35th European Conference on Surface Science (ECOSS2022), 29.08.-02.09.2022, University of Luxembourg, Belval Campus, Luxembourg

Publ.-Id: 35107

Exploring nitric oxide (NO)- releasing celecoxib derivatives as modulators of radioresponse in pheochromocytoma cells

Brandt, F.; Ullrich, M.; Seifert, V.; Haase-Kohn, C.; Richter, S.; Knieß, T.; Pietzsch, J.; Laube, M.

COX-2 can be considered as a clinically relevant molecular target for adjuvant, in particular radiosensitizing treatments. In this regard, using selective COX-2 inhibitors, e.g., in combination with radiotherapy or endoradiotherapy, represents an interesting treatment option. Based on our own findings that nitric oxide (NO)-releasing and celecoxib-derived COX-2 inhibitors (COXIBs) showed promising radiosensitizing effects in vitro, we herein present the development of a series of eight novel NO-COXIBs differing in the peripheral substitution pattern and their chemical and in vitro characterization. COX-1 and COX-2 inhibition potency was found to be comparable to the lead NO-COXIBs, and NO-releasing properties were demonstrated to be mainly influenced by the substituent in 4-position of the pyrazole (Cl vs. H). Introduction of the N-propionamide at the sulfamoyl residue as a potential prodrug strategy lowered lipophilicity markedly and abolished COX inhibition while NO-releasing properties were not markedly influenced. NO-COXIBs were tested in vitro for a combination with single-dose external X-ray irradiation as well as [ 177Lu]LuCl3 treatment in HIF2α-positive mouse pheochromocytoma (MPC-HIF2a) tumor spheroids. When applied directly before X-ray irradiation or 177Lu treatment, NO-COXIBs showed radioprotective effects, as did celecoxib, which was used as a control. Radiosensitizing effects were observed when applied shortly after X-ray irradiation. Overall, the NO-COXIBs were found to be more radioprotective compared with celecoxib, which does not warrant further preclinical studies with the NO-COXIBs for the treatment of pheochromocytoma. However, evaluation as radioprotective agents for healthy tissues could be considered for the NO-COXIBs developed here, especially when used directly before irradiation.

Keywords: cancer; endoradionuclide therapy; NO donors; pheochromocytoma; (pseudo)hypoxia; radiation therapy; selective cyclooxygenase-2 inhibitors

Publ.-Id: 35106

On Curie temperature of B20-MnSi films

Li, Z.; Yuan, Y.; Begeza, V.; Rebohle, L.; Helm, M.; Nielsch, K.; Prucnal, S.; Zhou, S.

B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi show a higher Curie temperature than their bulk counterpart. However, it is not yet clear what mechanism leads to the increase of the Curie temperature. In this work, we grow MnSi films on Si(100) and Si(111) substrates with a broad variation in their structures. By controlling the Mn thickness and annealing parameters, the pure MnSi phase of polycrystalline and textured nature as well as the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these MnSi films show an increased Curie temperature of up to around 43 K. The Curie temperature is likely independent of the structural parameters within our accessibility including the film thickness above a threshold, strain, cell volume and the mixture with MnSi1.7. However, a pronounced phonon softening is observed for all samples, which can tentatively be attributed to slight Mn excess from stoichiometry, leading to the increased Curie temperature.

Related publications

Publ.-Id: 35103

Combining Batch Experiments and Spectroscopy for realistic Surface Complexation Modelling of the Sorption of Americium, Curium, and Europium onto Muscovite

Bezzina, J. P.; Neumann, J.; Brendler, V.; Schmidt, M.

For a safe enclosure of contaminants, for instance in deep geological repositories of radioactive waste, any processes retarding metal migration are of paramount importance. This study focusses on the sorption of trivalent actinides (Am, Cm) and lanthanides (Eu) to the surface of muscovite, a mica and main component of most crystalline rocks (granites, granodiorites). Batch sorption experiments quantified the retention regarding parameters like pH (varied between 3 and 9), metal concentration (from 0.5 µM Cm to 10 µM Eu), or solid-to-liquid ratio (0.13 and 5.25 g·L-1). In addition, time-resolved laser fluorescence spectroscopy (TRLFS) using the actinide Cm(III) identified two distinct inner-sphere surface species. Combining both approaches allowed the development of a robust surface complexation model and the determination of stability constants of the spectroscopically identified species of (≡S OH)2M3+ (logKo −8.89), (≡S O)2M+ (logKo −4.11), and (≡S-O)2MOH (logKo −10.6), with all values extrapolated to infinite dilution. The inclusion of these stability constants into thermodynamic databases will improve the prognostic accuracy of lanthanide and actinide transport through groundwater channels in soils and crystalline rock systems.

Keywords: mica; trivalent actinides; retardation; TRLFS; Diffuse Double Layer Model


  • Secondary publication expected from 28.08.2023

Publ.-Id: 35102

ExPaNDS D5.5: Dedicated websites and e-platforms with the teaching material

Knodel, O.; Padovani, A.

The purpose of this task is to coordinate with the e-platforms providers (ESRF for PaNOSC and EGI for EOSC-hub) to jointly define the prerequisites to maximise and expand the use of the platforms as appropriate. WP2, WP3 and WP4 will work closely with WP5 and WP6 to deliver a tailored specification for each of the online training modules. The output of WP5 will be a definition of the most suitable training materials in accordance with the requirements and recommendations made by the targeted e-platform providers.
A unique joint PaN training portal has been developed and deployed to provide both a training material and events catalogue (ExPaNDS) as well as an e-learning system (PaNOSC) under the domain

Keywords: PaN-training; PaN portal; ExPaNDS; e-learning; TeSS; Photon science; Neutron science; EOSC Portal

Publ.-Id: 35101

New insights into uranium(VI) reduction by a sulfate-reducing bacterium relevant to nuclear waste disposal

Hilpmann, S.; Steudtner, R.; Roßberg, A.; Kvashnina, K.; Prieur, D.; Bauters, S.; Hübner, R.; Stumpf, T.; Cherkouk, A.

For a comprehensive safety assessment of a nuclear repository, the influence of naturally occurring microorganisms from deep geological layers has to be taken into account. Clay rock represents a suitable host rock for the long-term storage of high-level radioactive waste with bentonite as backfill material. In the event of a worst-case scenario, water can enter the repository, solubilize components of the waste, and transport it into the surrounding barriers. In this case, microorganisms can interact with the radionuclides and thereby change the chemical speciation or induce redox reactions.
Desulfosporosinus species represent important members of anaerobic, sulfate-reducing bacteria present in both, clay rock and bentonite. They occur, among others, in the pore water of Opalinus Clay and in the Bavarian bentonite B25. [1,2] Desulfosporosinus hippei DSM 8344T is a close phylogenetic relative to an isolated bacterium from bentonite samples. [3] Therefore, this strain was selected to get a more profound insight into the uranium(VI) interactions, especially regarding the reduction to the less mobile uranium(IV).
Artificial Opalinus Clay pore water [4] served as background electrolyte for the reduction experiments (100 µM uranium(VI), pH 5.5), in which the uranium concentrations in the supernatants decreased rapidly. Time-resolved laser-induced fluorescence spectroscopy showed the presence of a uranyl lactate and a uranyl carbonate complex as aqueous species in the supernatant. While the proportion of the uranyl lactate complex decreased with the incubation time, the uranyl carbonate fraction remained almost constant.
UV/Vis studies of the dissolved cell pellets provided clear proof of a partial reduction of uranium(VI) to uranium(IV) of up to 39% in the samples. Therefore, a combined association-reduction process is a possible interaction mechanism.
TEM images showed the presence of uranium-containing aggregates on the cell surface. To mitigate encrustation, cells released membrane vesicles as a possible defense mechanism.
In addition, uranium(VI) reduction was confirmed by HERFD-XANES measurements. Moreover, uranium(V) could be detected as an intermediate, providing first evidence of the involvement of uranium(V) in uranium(VI) reduction by sulfate-reducing microorganisms. EXAFS measurements helped to identify different cell-related uranium species.
This study helps to improve the understanding of the complexity of uranium-microbe interactions relevant to the long-term storage of high-level radioactive waste in clay rock and therefore contributes to a safety concept for a nuclear repository in this host rock.
[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: Sulfate-reducing bacteria; Uranium(VI) reduction; Clay rock; Opalinus Clay pore water

  • Lecture (Conference)
    DECAY Days 2022, 21.-23.09.2022, St. Ursanne, Schweiz

Publ.-Id: 35100

Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

Ugalde, H.; Morris, W.; Madriz Diaz, Y. C.; Kirsch, M.; Gloaguen, R.; Schneider, M.; Schiffler, M.; Siemon, B.; Fréville, T.; Munschy, M.

Magnetic data can be acquired from a number of different platforms (e.g., ground, drone, helicopter) using a variety of sensors (e.g., caesium vapour-type optically pumped magnetometers, fluxgate, superconducting quantum interference devices) with different flight line configurations. To detect a magnetic anomaly associated with a mineral commodity that is not exposed but is thought to be associated with the anomalous magnetic mineral content, it is necessary to optimize the survey parameters through a complete data integration process. Prior petrophysical measurements provide insight into the physical contrast that might be expected between adjacent lithologic units and between the ore zone and the encompassing lithology. Oriented rock samples provide access to magnetic remanence data through palaeomagnetic laboratory measurements. Knowing the typical morphology of the ore zone one can compute a forward model of the expected anomalous response and determine which combination of survey parameters provides the highest probability of detecting the commodity being sought. In this study, we analyse magnetic patterns associated with thin dipping skarn bodies from the Geyer mining district in Erzgebirge, Germany. Petrophysical measurements indicate that the skarns are more magnetic than the surrounding host rock. Partially oriented samples from a bore core record a Variscan age metamorphic remanence. Forward modelling indicates that clusters of skarn bodies are required to produce a reliably detectable magnetic signal. Ground, or low elevation drone surveys are needed to detect these anomalies with standard scalar-type optically pumped magnetometer or fluxgate magnetic surveys. The enhanced spatial resolution and long-wavelength rejection of a superconducting quantum interference device-based full-tensor magnetic gradiometer provide an improvement over optically pumped magnetometers for an aircraft-based survey platform.

Keywords: Acquisition; Interpretation; Magnetics; Potential fields

Publ.-Id: 35099

HELIPORT — An Integrated Research Data Lifecycle

Knodel, O.; Pape, D.; Voigt, M.; Gruber, T.; Kelling, J.; Lokamani, M.; Müller, S.; Juckeland, G.; Kessler, A.; Hein, J.; Lee, C.-L.; Kaluza, M.; Schuller, B.

HELIPORT is a data management solution that aims at making the components and steps of the entire research experiment’s life cycle discoverable, accessible, interoperable and reusable according to the FAIR principles.
Among other information, HELIPORT integrates documentation, scientific workflows, and the final publication of the research results - all via already established solutions for proposal management, electronic lab notebooks, software development and devops tools, and other additional data sources. The integration is accomplished by presenting the researchers with a high-level overview to keep all aspects of the experiment in mind, and automatically exchanging relevant metadata between the experiment’s life cycle steps.
Computational agents can interact with HELIPORT via a REST API that allows access to all components, and landing pages that allow for export of digital objects in various standardized formats and schemas. An overall digital object graph combining the metadata harvested from all sources provides scientists with a visual representation of interactions and relations between their digital objects, as well as their existence in the first place. Through the integrated computational workflow systems, HELIPORT can automate calculations using the collected metadata.
By visualizing all aspects of large-scale research experiments, HELIPORT enables deeper insights into a comprehensible data provenance with the chance of raising awareness for data management.

Keywords: Data Management; Metadata; FAIR; Data provenance; Digital Objects; Workflows

  • Open Access Logo Poster
    German Conference for Research with Synchrotron Radiation, Neutrons and on Beams at Large Facilities, 05.-07.09.2022, Freie Universität Berlin, Germany
  • Open Access Logo Poster
    3. SaxFDM Tagung 2022, 22.09.2022, Leipzig, Deutschland
  • Open Access Logo Poster
    8. Annual MT Meeting, 26.-27.09.2022, Hamburg, Deutschland
  • Open Access Logo Poster (Online presentation)
    Helmholtz Metadata Collaboration | Conference 2022, 05.-06.10.2022, online, online
    DOI: 10.5281/zenodo.7104941


Publ.-Id: 35097

Changes in Radical Levels as a Cause for the FLASH effect: Impact of beam structure parameters at ultra-high dose rates on oxygen depletion in water

Jansen, J.; Beyreuther, E.; García-Calderón, D.; Karsch, L.; Knoll, J.; Pawelke, J.; Schürer, M.; Seco, J.

The influence of different average and bunch dose rates in electron beams on the FLASH effect was investigated. The present study measures O2 content in water at different beam pulse patterns and finds strong correlation with biological data, strengthening the hypothesis of radical-related mechanisms as a reason for the FLASH effect.

Keywords: FLASH effect; oxygen depletion; pulse structure; radical reduction

Related publications

Publ.-Id: 35096

Long-term evolution of the neutron rate at the Canfranc Underground Laboratory

Orrigo, S. E. A.; Tain, J. L.; Mont-Geli, N.; Tarifeño-Saldivia, A.; Fraile, L. M.; Grieger, M.; Agramunt, J.; Algora, A.; Bemmerer, D.; Calviño, F.; Cortés, G.; de Blas, A.; Dillmann, I.; Domínguez Bugarín, A.; García, R.; Nacher, E.; Tolosa-Delgado, A.

We report results on the long-term variation of the neutron counting rate at the Canfranc Underground Laboratory, of importance for several low-background experiments installed there, including rare-event searches. The measurement campaign was performed employing the High Efficiency Neutron Spectrometry Array (HENSA) mounted in Hall A and lasted 412 live days. The present study is the first long-term measurement of the neutron rate with sensitivity over a wide range of neutron energies (from thermal up to 0.1 GeV and beyond) performed in any underground laboratory so far. Data on the environmental variables inside the experimental hall (radon concentration, air temperature, air pressure and humidity) were also acquired during all the measurement campaign. We have investigated for the first time the evolution of the neutron rate for different energies of the neutrons and its correlation with the ambient variables.

Keywords: neutron; underground laboratory; hensa; background

Publ.-Id: 35095

Optoelectronic properties of 2D perovskites and other inorganic-organic hybrid materials

Kuc, A. B.

Summary of the CRC1415 project C03 progress. Published results since the beginning of the project were shown.

  • Lecture (others)
    Retreat of CRC1415 project, 15.-17.06.2022, Lichtenwalde, Germany

Publ.-Id: 35094

Modelling TMDC/2D perovskite heterostructures for charge and energy transfer

Kuc, A. B.

Modelling of 2D TMDC/2D perovskite heterostructures is shown together with experimental data. Nonradiative energy transfer and charge transfer were found to co-exist in this type of heterostructures.

  • Lecture (Conference)
    Midterm meeting of SPP2244, 21.-23.03.2022, Dresden, Germany

Publ.-Id: 35092

Modelling van der Waals heterostructures for experimental collaborations

Kuc, A. B.

Modelling of 2D van der Waals heterostructures is discussed from the point of view of complexity and desired property investigations. Different models are shown together with appropriate approached to simulate properties of materials.

  • Invited lecture (Conferences)
    Semiconductor Materials Engineering Seminar, 25.02.2022, Wroclaw, Poland

Publ.-Id: 35090

Simulation of hydrogen species diffusion and transport between and through layers of 2D materials

Kuc, A. B.

Recent experiments by Geim’s group have demonstrated transport and separation of hydrogen isotopes through the van der Waals gap in hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2) bulk layered materials. The experiments could not distinguish whether the transported particles are protons (H+) or protium (H) atoms. In one of our recent works, we reported theoretical studies, which indicate that protium atoms, rather than protons, are transported through the gap.[1] First-principles calculations combined with well-tempered metadynamics simulations at finite temperature reveal that for h-BN and MoS2, the diffusion mechanism of both protons and protium (H) atoms involves a hopping process between adjacent layers. This process is assisted by low-energy phonon shear modes. The extracted diffusion coefficient of protium matches the experiment, while for protons, it is several orders of magnitude smaller. This indicates that H atoms are responsible for the experimental observations. These results allow for a comprehensive interpretation of experimental results on the transport of H isotopes through van der Waals gaps and can help identify other materials for hydrogen isotope separation applications.
In more recent investigations, we focus on H atom diffusion between layers of transition-metal dichalcogenides (TMDCs), such as MoS2, where we investigate the impact of transition metal atom, chalcogen atom, stacking order, and moiré pattern on the diffusion coefficients. We want to learn whether the free energy barriers are lowered (resulting in higher diffusion coefficients) and whether the moiré patterns can enforce directional transport.
We use well-tempered metadynamics simulations in our studies as implemented in the cp2k code. Our approach to H atom diffusion can be extended to investigations of other species, such as Eu(III)-species diffusion in clay mineral layered materials.
[1] Y. An, A. Kuc, P. Petkov, M. Lozada-Hidalgo, T. Heine, Small 1901722 (2019) 1-7.

  • Lecture (Conference)
    Casuscon 2022, 11.-14.07.2022, Wroclaw, Poland

Publ.-Id: 35089

Modelling 2D materials for experimental collaborations

Kuc, A. B.

In this summer school, I was introducing simulations of electronic and vibrational properties of 2D materials in the form of a lecture.

  • Invited lecture (Conferences)
    2D-Mat School, 24.-29.07.2022, Bad Honnef, Germany

Publ.-Id: 35088

Investigating the influence of multiple particle properties on the separation of ultrafine particles via enhanced froth flotation

Sandbrink, J.; Rudolph, M.

One of the most important techniques to separate valuable minerals from unwanted gangue is froth flotation. It is an efficient process for particles with sizes ranging from 10 µm to 200 µm and its main separation feature is the difference in particle wettabilities. As particles are getting finer, existing flotation techniques need to be adapted and improved in order to have an efficient separation. For that reason, this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, aims at developing a method for the separation of ultrafine particles based on multiple particle properties, such as size, morphology or surface energy.
A particle system consisting of ultrafine size fractions of glass particles as the valuable material and magnetite as the gangue material is used for this study. The wettability of the glass particles is modified via an esterification reaction using alcohols with differing chain length and the resulting wettability states are analysed using inverse gas chromatography as well as analytic particle solvent extraction. Information on the particle size and shape are obtained via a combination of laser diffraction and microscopic analysis. The technique of flow cytometry is introduced for multidimensional particle characterization, as it allows for simultaneous size and shape analysis. Additionally, information on the particle wettability can be obtained by fluorescent marking of particles with dyes. All flotation tests are carried out in batch mode using a novel flotation apparatus, specifically designed for the flotation of ultrafine particles by combining advantages from machine-type froth flotation and column flotation and the separation process is evaluated using multidimensional partition curves.
This investigation will help to further understand how certain particle properties influence flotation, as well as other separation processes. In this way, the separation of ultrafine particles will be more efficient, which will play an important role in the recycling of secondary materials.

Keywords: ultrafine particles; multidimensional separation; flotation; particle characterization; partition curves

  • Lecture (Conference)
    9th World Congress on Particle Technology, 18.-22.09.2022, Madrid, Spanien

Publ.-Id: 35087

Nonradiative Energy Transfer and Selective Charge Transfer in TMDC/2D perovskite Heterostructures

Kuc, A. B.

Van der Waals heterostructures are currently the focus of intense investigation; this is essentially due to the unprecedented flexibility offered by total relaxation of lattice matching requirements and their new and exotic properties compared to the individual layers. Here, we investigate hybrid transition-metal dichalcogenide (TMDC)/2D perovskite heterostructures. We present the first density functional theory (DFT) calculations of a such ensembles, which reveal a novel band alignment, where direct electron transfer is blocked by the organic spacer of the 2D perovskite. In contrast, the valence band forms a cascade from TMDC through the organic linkers to the inorganic part of the perovskite allowing a hole transfer. These predictions are supported by optical spectroscopy studies, which provide compelling evidence for both charge transfer and nonradiative transfer of the excitation (energy transfer) between the layers. Our results show that TMDC/2D perovskite heterostructures provide a flexible and convenient way to engineer the band alignment.

  • Lecture (Conference)
    Psi-k conference 2022, 22.-25.08.2022, Lausanne, Switzerland

Publ.-Id: 35086

MultiDimFlot - Multidimensional separation of ultrafine particles using a mechanical flotation cell combined with froth fractionation

Sandbrink, J.; Rudolph, M.

Froth flotation is one of the most important techniques in the mining industry for the efficient separation of particles with sizes between 10 µm and 200 µm. The separation process is based on the difference in particle wettabilities, as hydrophobic particles attach to a gas bubble and are recovered in a froth, whereas hydrophilic particles tend to stay in the pulp. Although, the wettability is the most prominent separation feature, the micro processes that occur in the pulp and in the froth zone include complex interactions between the particles and the bubbles and also other particle properties, such as size, morphology, surface energy or the dispersion state have an impact on the separation.
Low ore grades and very fine composite particles in electronic devices are forcing the industry to adapt and improve existing flotation techniques to the processing of ultrafine particles (< 10 µm), as the material needs to be milled down to finer size fractions to obtain sufficient liberation of the valuable minerals. For that reason, the project “MultiDimFlot”, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, aims at developing a method for the separation of ultrafine particles (< 10 µm) based on multiple particle properties.
A novel separation apparatus is used that combines the advantages of a mechanical flotation cell that comes with a high particle-bubble collision rate (thus a high recovery) with those from a flotation column with a fractionating effect due to its deep froth (thus a high grade). An academic particle system, consisting of glass spheres, glass fragments and glass fibres as the valuable material and magnetite as the gangue material is used, whose particle properties are studied in depth. These investigations will help to further understand the behaviour of ultrafine particles during flotation and how certain particle properties affect the separation process. Furthermore, the possibilities and limitations of different analysis techniques, e.g. coupled SEM-EDX, flow cytometry or inverse gas chromatography are investigated for their use in ultrafine particle characterization.

Keywords: Ultrafine particles; multidimensional separation; flotation; partition curves

  • Poster
    9th World Congress on Particle Technology, 18.-22.09.2022, Madrid, Spanien

Publ.-Id: 35085

Numerical investigation of the flow inside a precession driven cylindrical cavity with additional baffles using an Immersed Boundary Method

Wilbert, M.; Giesecke, A.; Grauer, R.

In this paper we present a numerical approach to
solve the Navier-Stokes equations for arbitrary vessel geometries by
combining a Fourier-Spectral method with a direct forcing
Immersed Boundary method which allows to consider solid-fluid
The approach is applied to a paradigmatic setup motivated by the precession dynamo experiment currently
under construction at Helmholtz-
Zentrum Dresden-Rossendorf (\textit{HZDR}). The experiment
consists of a fluid filled cylinder rotating about 2 axes which
induces a precession driven flow inside the cavity. The cylinder is
also equipped with baffles at the end caps with adjustable penetration depth
to impact the flow. The numerical details as well as simulation
results for the spin-up and precession driven flow in a circular cylinder
with additional baffles are presented.
The results provide a first confirmation that the use of such
baffles in the precession dynamo experiment is a useful way of influencing the flow,
allowing more efficient driving without changing the known flow
structure too much.

Keywords: DRESDYN; Immersed Boundary Method; Spectral; Dynamo

  • Physics of Fluids 34(2022), 096607


Publ.-Id: 35084

Radiosynthesis and preclinical evaluation of an 18F-labeled tri-azolopyridopyrazine-based inhibitor for neuroimaging of the phosphodiesterase 2A (PDE2A)

Wenzel, B.; Fritzsche, S. R.; Toussaint, M.; Briel, D.; Kopka, K.; Brust, P.; Scheunemann, M.; Deuther-Conrad, W.

The cyclic nucleotide phosphodiesterase 2A is an intracellular enzyme which hydrolyzes the secondary messengers cAMP and cGMP and therefore plays an important role in signaling cas-cades. A high expression in distinct brain areas as well as in cancer cells makes PDE2A an inter-esting therapeutic and diagnostic target for neurodegenerative and neuropsychiatric diseases as well as for cancer. Aiming at a specific imaging of this enzyme in the brain with positron emis-sion tomography (PET), a new triazolopyridopyrazine-based derivative (11) was identified as a potent PDE2A inhibitor (IC50, PDE2A = 1.99 nM; IC50, PDE10A ~ 2000 nM) and has been radiofluorinated for biological evaluation. In vitro autoradiographic studies revealed that [18F]11 binds with high affinity and excellent specificity towards PDE2A in the rat brain. For the PDE2A-rich region nu-cleus caudate and putamen an apparent KD value of 0.24 nM and an apparent Bmax value of 16 pmol/mg protein were estimated. In vivo PET-MR studies in rat showed a moderate brain uptake of [18F]11 with a highest standardized uptake value (SUV) of 0.97. However, no considerable en-richment in PDE2A-specific regions in comparison to a reference region was detectable (SUVcau-date putamen = 0.51 vs. SUVcerebellum = 0.40 at 15 min p.i.). Furthermore, metabolism studies revealed a considerable uptake of radiometabolites of [18F]11 in the brain (66% parent fraction at 30 min p.i.). Altogether, despite the low specificity and the blood-brain barrier crossing of radiometab-olites observed in vivo, [18F]11 is a valuable imaging probe for the in vitro investigation of PDE2A in the brain and has potential as a lead compound for further development of a PDE2A-specific PET ligand for neuroimaging.

Keywords: PDE2A inhibitor; triazolopyridopyrazine; fluorine-18; small animal PET-MR; autoradiography; in vivo metabolism

Publ.-Id: 35082

Engineering of excitonic g-factors in van der Waals structures

Wozniak, T.; Faria Junior, P. E.; Chaves, A.; Kunstmann, J.; Kuc, A. B.

We develop a fully ab-initio based method of calculation of excitonic g-factors, which describe their energy dependence on external magnetic field, and apply it to 1L TMDs and MoSe2/WSe2 heterobilayers, obtaining excellent agreement with experimental data for intra- and interlayer excitons. A proper inclusion of stacking-dependent selection rules allows to assign the measured optical peaks to specific transitions in the band structure and regions of the samples [1]. We identify a series of magneto-PL peaks in 1L WS2 based on the calculated g-factors of excitons, trions and biexcitons, as well as four phonon replicas of the dark trion. We obtain a perfect agreement of the individual bands g-factors with the values derived from experimental data [2]. We explain the reduction of a g-factor measured in MoSe2/WS2 by the spatial confinement of the mixed exciton in the moiré potential [3].
[1] PRB 105, 235408
[2] NanoLett 21, 2519
[3] arX:2204.01813

  • Lecture (Conference)
    Psi-k conference 2022, 22.-25.08.2022, Lausanne, Switzerland

Publ.-Id: 35080

Impact of blood parameters and normal tissue dose on treatment outcome in esophageal cancer patients undergoing neoadjuvant radiochemotherapy

Bütof, R.; Häberlein, L.; Jentsch, C.; Kotzerke, J.; Lohaus, F.; Makocki, S.; Valentini, C.; Weitz, J.; Löck, S.; Troost, E. G. C.

Despite technological advances, normal tissue sparing in photon beam irradiation is still challenging. Since in esophageal cancer this may inflict damage on the lungs, heart and bone marrow, possibly impacting on outcome, the aim of this study was to investigate the association of normal tissue dose and blood parameters on the survival of patients having undergone neoadjuvant radiochemotherapy (RCTx) followed by surgery. This retrospective study included 125 patients irradiated to 40–41.4 Gy with photons or protons combined with concurrent chemotherapy. On initial and restaging 18F-FDG-PET/CT, the lungs and heart were contoured as organs at risk for which standardized uptake values (SUV) were evaluated. The mean radiation dose (Dmean) to the lungs and
heart, the volume of the lungs receiving at least 20 Gy (V20Gy_lung) and various pre- and per-treatment blood parameters were included in the Cox regression analyses. Results: The median follow-up time was 19.8 months and median overall survival 37 months (95% confidence interval: 16–58.9 months). In multivariate analysis, higher radiation doses to the lungs and heart were statistically significantly associated with decreased overall survival (Dmean_lung: p < 0.001; V20Gy_lung: p < 0.002; Dmean_heart: p = 0.005). Neither the 18F-FDG-PET nor blood parameters were predictive for overall survival. In patients with locally advanced esophageal cancer treated with RCTx, the radiation dose to the heart and lungs was significantly associated with overall survival.

Keywords: esophageal cancer; radiochemotherapy; normal tissue dose; neoadjuvant; outcome; PET; blood parameter

  • Open Access Logo Cancers 14(2022)14, 3504

Publ.-Id: 35079

Deutschlands Ausstieg aus der Atomkraft - Was passiert mit dem Müll und welche Rolle spielen Mikroorganismen?

Matschiavelli, N.

Vortrag über mikrobiologische Themen in der Abteilung Biogeochemie am HZDR

  • Invited lecture (Conferences)
    Tag der Wissenschaften, 24.11.2022, Dresden, Deutschland

Publ.-Id: 35078

Fracture Mechanics Testing of Neutron Irradiated RPV Steels using Mini-C(T) Specimens

Das, A.; Chekhonin, P.; Houska, M.; Obermeier, F.; Altstadt, E.

Neutron irradiation induced embrittlement of the reactor pressure vessel (RPV) reduces the operating lifetime of nuclear reactors and leads to an increase in the transition temperature T0. Fracture mechanics testing of RPV steels before and after neutron irradiation, which reveals the shift in T0, is often limited by the shortage of irradiated material. To solve this, we tested sub-sized 0.16T C(T) specimens manufactured from already tested SE(B) standard Charpy sized specimens using the Master Curve concept. The transferability of fracture mechanics data from small to standard sized specimens forms a key part of this study. To investigate the effect of chemical composition on neutron irradiation, four western RPV steels are chosen in this study, three base and one weld metal. Fractography is performed on broken mini-C(T) specimens using scanning electron microscopy in order to determine the location of the fracture initiating particles as well as the mode of fracture. In order to make the testing procedure simpler, based on large statistical data, we studied the impact of the slow stable crack growth censoring criterion on the determination of T0. We found that the results from the small specimens are comparable to the standard specimens. RPV steels containing higher amounts of Cu, Ni and P exhibit a higher increase in T0 after irradiation. The fracture initiating particles were located at greater distances from the crack front in irradiated specimens of the weld material as compared to the unirradiated specimens. The fracture toughness of all materials remained constant for similar test temperatures irrespective of their irradiation state. Furthermore, we found that the stable crack growth censoring criterion did not influence the T0 significantly. Our results demonstrate the validity of small specimen testing and confirms the role of the impurity elements Cu and P in neutron embrittlement.

Keywords: Fracture mechanics testing; sub-sized specimen; transition temperature; reactor pressure vessel steels; Master Curve; neutron-irradiation

  • Lecture (Conference)
    The Nuclear Materials Conference 2022, 24.-28.10.2022, Ghent, Belgium

Publ.-Id: 35077

Development of Radiotracers for Imaging of the PD-1/PD-L1 Axis

Krutzek, F.; Kopka, K.; Stadlbauer, S.

Immune checkpoint inhibitor (ICI) therapy has emerged as a major treatment option for a variety of cancers. Among the immune checkpoints addressed, the programmed death receptor 1 (PD-1) and its ligand PD-L1 are the key targets for an ICI. PD-L1 has especially been proven to be a reproducible biomarker allowing for therapy decisions and monitoring therapy success. However, the expression of PD-L1 is not only heterogeneous among and within tumor lesions, but the expression is very dynamic and changes over time. Immunohistochemistry, which is the standard diagnostic tool, can only inadequately address these challenges. On the other hand, molecular imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) provide the advantage of a whole-body scan and therefore fully address the issue of the heterogeneous expression of checkpoints over time. Here, we provide an overview of existing PET, SPECT, and optical imaging (OI) (radio)tracers for the imaging of the upregulation levels of PD-1 and PD-L1. We summarize the preclinical and clinical data of the different molecule classes of radiotracers and discuss their respective advantages and disadvantages. At the end, we show possible future directions for developing new radiotracers for the imaging of PD-1/PD-L1 status in cancer patients.

Keywords: tumor microenvironment; PD-1/PD-L1 targeting radiotracer; immune checkpoint; molecular imaging

Publ.-Id: 35076

Coacervation-induced viscous fingering by surfactant-polymer interaction

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

The dynamics of a fluid’s displacement by another fluid are always dictated by the viscosity contrast between the two due to phenomena related to the Saffman-Taylor instability. In this study, a miscible displacement of a less viscous liquid by a more viscous shear-thinning liquid in a Hele-Shaw cell was investigated. Due to a coacervation process between the two fluids, a hydrodynamic instability, in the form of inward viscous fingering, appears, in an otherwise hydrodynamically stable system. The aqueous miscible system used consisted of an anionic xanthan gum dispersion, as the injection liquid, which displaced a cationic C14TAB solution. The two oppositely charged species form polymer-surfactant complexes due to electrostatic interactions, which in turn separate from the water phase forming a gel-like membrane. In the course of the displacement, a variety of patterns was observed, the mechanism behind of them is suspected to be governed by a synergy of background contributing factors related 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 as well as the mechanisms related to the membrane growth. The displacement flow rate and the Hele-Shaw cell gap width were found to determine the distinct displacement regimes; one viscosity-dominated, the other buoyancy-dominated. The above aspects are relevant to applications of displacement-involving coacervation systems in engineering and technology.

  • Poster
    Oscillations and Dynamic Instabilities in Chemical Systems, 17.07.2022, Easton, MA, USA

Publ.-Id: 35075

Coupled thermo-fluid-mechanical FEM simulations for thermoelastic harvesting of low-grade waste heat

Neumann, B.; Eckert, K.; Fähler, S.

In a world that heats up, it is essential to use primary energy as efficient as possible. This includes the need to recover waste heat. However, in particular for low grade waste heat hardly any suitable technology is available. Here we simulate the conversion of waste heat into mechanical energy with a NiTi shape memory wire through the coupling of heat exchange, fluid mechanics and structural mechanics. We investigate the influence of preload on the wire and temperature of the fluid to optimize the thermodynamic efficiency, which could act as a base for more complex energy harvesting solutions using shape memory alloys (SMA).

Keywords: Energy; FEM; Thermoelastic Energy Harvesting; simulation

  • Contribution to proceedings
    European Simulation and Modelling Conference 2022, 26.-28.10.2022, Porto, Portugal, 978-9-492859-24-2

Publ.-Id: 35074

Impact of curvature-induced Dzyaloshinskii-Moriya interaction on magnetic vortex texture in spherical caps

Sloika, M.; Gaididei, Y.; Kravchuk, V.; Pylypovskyi, O.; Makarov, D.; Sheka, D.

Geometric curvature of nanoscale magnetic shells brings about curvature-induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI). Here, we derive equations to describe the profile of the magnetic vortex state in a spherical cap. We demonstrate that the azimuthal component of magnetization acquires a finite tilt at the edge of the cap, which results in the increase of the magnetic surface energy. This is different compared to the case of a closed spherical shell, where symmetry of the texture does not allow any tilt of magnetization at the equator of the sphere. Furthermore, we analyze the size of the vortex core in a spherical cap and show that the presence of the curvature-induced DMI leads to the increase of the core size independent of the product of the circulation and polarity of the vortex. This is in contrast to the case of planar disks with intrinsic DMI, where the preferred direction of circulation as well as the decrease or increase of the size of vortex core is determined by the sign of the product of the circulation and polarity with respect to the sign of the constant of the intrinsic DMI.

Keywords: curvilinear magnetism; ferromagnet; cap; Dzyaloshinskii-Moriya interaction

Publ.-Id: 35073

Circular stripe domains and cone state vortices in disk-shaped exchange coupled magnetic heterostructures

Zaiets, O.; Kravchuk, V.; Pylypovskyi, O.; Makarov, D.; Sheka, D.

Vertically stacked exchange coupled magnetic heterostructures of cylindrical geometry can host complex noncolinear magnetization patterns. By tuning the interlayer exchange coupling between a layer accommodating magnetic vortex state and an out-of-plane magnetized layer, one can efficiently realize new topological chiral textures such as cone state vortices and circular stripe domains. We study how the number of circular stripes can be controlled by both the interlayer exchange coupling and the sample geometrical parameters. By varying geometrical parameters, a continuous phase transition between the homogeneous state, cone state vortex, circular stripe domains, and the imprinted vortex takes place, which is analysed by full scale micromagnetic simulations. The analytical description provides an intuitive pictures of the magnetization textures in each of these phases. The possibility to realize switching between different states allows for engineering magnetic textures with possible applications in spintronic devices.

Keywords: multilayer; vortex; heterostructure; stripe domain

Publ.-Id: 35072

Wafer-scale nanofabrication of telecom single-photon emitters in silicon

Hollenbach, M.; Klingner, N.; Jagtap, N.; Bischoff, L.; Fowley, C.; Kentsch, U.; Hlawacek, G.; Erbe, A.; Abrosimov, N. V.; Helm, M.; Berencen, Y.; Astakhov, G.

A highly promising route to scale millions of qubits is to use quantum photonic integrated circuits (PICs), where deterministic photon sources, reconfigurable optical elements, and single-photon detectors are monolithically integrated on the same silicon chip. The isolation of single-photon emitters, such as the G centers and W centers, in the optical telecommunication O-band, has recently been realized in silicon. In all previous cases, however, single-photon emitters were created uncontrollably in random locations, preventing their scalability. Here, we report the controllable fabrication of single G and W centers in silicon wafers using focused ion beams (FIB) with a probability exceeding 50%. We also implement a scalable, broad-beam implantation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabricate single telecom emitters at desired positions on the nanoscale. Our findings unlock a clear and easily exploitable pathway for industrial-scale photonic quantum processors with technology nodes below 100 nm.

Keywords: Quantum technology; Single photons; Ion implantation; Silicon photonics; Optical telecommunication; CMOS-compatible processing

Related publications

Publ.-Id: 35071

ARIEL & SANDA nuclear data activities

Franzen, C.; Junghans, A.; Gonzalez, E. M.; Plompen, A. J. M.

Nuclear data are fundamental quantities for developing nuclear energy concepts and research.
They are essential for the simulation of nuclear systems, safety and performance calculations, and reactor
instrumentation. Nuclear data improvement requires a combination of many different know-hows that are
distributed over many institutions along Europe. In the EURATOM call for Nuclear Fission and Radiation
Protection NFRP-2018, two nuclear data projects were started in September 2019: The Coordination and
Support Action ARIEL (Accelerator and Research reactor Infrastructures for Education and Learning)
and the Research and Innovation Action SANDA (Solving Challenges in Nuclear Data for the Safety of
European Nuclear facilities). The ARIEL project integrates education and training of young scientists and
technicians with access to neutron beam research infrastructures and supports scientific visits to conduct
short-term research projects relevant to thesis works. The SANDA project is focuses on research innovation
actions, including detector and nuclear target development, important nuclear data measurements, nuclear
data evaluation, and validation. A description of these ongoing projects, including the first results, is the
subject of this article.

Publ.-Id: 35070

Direct Sampling Strategy for Extensive Hard Data-based Training Image

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

Extensive hard data could potentially replace the training image in doing MPS. However, direct use of the the standard MPS Direct Sampling algorithm will typically not produce proper results, owing to the absence (or at least, sufficient replication) of every necessary data pattern in the data set. As a result, during the step of training image scanning, there will be a reduction of the conditional data neighbourhood in the simulation grid data event, generating inconsistencies of neighbourhood size in simulating each point. Here, we propose to use a spatial tolerance in extracting the training image data events. This has long been used to obtain experimental variogram in two-point geostatistics, and is also common in high-order cumulant based methods.

A synthetic case study of a fluvial depositional environment will be presented, together with a comparison of the usage of various types of training images (e.g. hard data, complete training image, multiple training images). This framework can also be extended to MPS for the purpose of estimation rather than simulation.
This is achieved by obtaining marginal
conditional probabilities by storing potential simulated values during the training image scan-
ning step for each grid cell, conditioning only to hard data. This could be a time saver for
users interested only in the point-wise statistics of the realizations without having to generate
multiple realizations.

Keywords: Extensive hard data; Direct Sampling; Multi-point geostatistics

  • Lecture (Conference)
    IAMG 2022 - 21st Annual Conference, 29.08.-03.09.2022, Nancy, France

Publ.-Id: 35069

Observation of Collective Resonance Modes in a Chiral Spin Soliton Lattice with Tunable Magnon Dispersion

Shimamoto, Y.; Matsushima, Y.; Hasegawa, T.; Kousaka, Y.; Proskurin, I.; Kishine, J.; Ovchinnikov, A. S.; Trindade Goncalves, F. J.; Togawa, Y.

A chiral spin soliton lattice (CSL), one of the representative systems of a magnetic superstructure, exhibits reconfigurability in periodicity over a macroscopic length scale. Such coherent and tunable characteristics of the CSL lead to an emergence of elementary excitation of the CSL as phononlike modes due to translational symmetry breaking and bring a controllability of the dispersion relation of the CSL phonon. Using a broadband microwave spectroscopy technique, we directly found that higher-order magnetic resonance modes appear in the CSL phase of a chiral helimagnet CrNb3S6, which is ascribed to the CSL phonon response. The resonance frequency of the CSL phonon can be tuned between 16 and 40 GHz in the vicinity of the critical field, where the CSL period alters rapidly. The frequency range of the CSL phonon is expected to extend over 100 GHz as extrapolated on the basis of the theoretical model. The present results indicate that chiral helimagnets could work as materials useful for broadband signal processing in the millimeter-wave band.

Keywords: Chiral helimagnetism; Collective spin dynamics; Ferromagnetic resonance; Magnon dispersion; DMI materials; Bulk crystals

Publ.-Id: 35068

Data publication: Importance of valence-band anharmonicity and carrier distribution for third- and fifth-harmonic generation in Si:B pumped with intense terahertz pulses

Meng, F.; Walla, F.; Ul-Islam, Q.; Pashkin, O.; Schneider, H.; Jungemann, C.; Thomson, M. D.; Roskos, H. G.

High-hamonic spectra induced by FEL pumping; FTIR and THz transmission spectra of utilized spectral filters

Related publications


Publ.-Id: 35067

Time-resolved measurements in pulsed magnetic fields

Kohama, Y.; Nomura, T.; Zherlitsyn, S.; Ihara, Y.

Tracking the time-dependence of a state and its observable, i.e., time-resolved measurement, is one of the ways of understanding physical principles of the system. In this Perspective, we review some of the time-resolved measurements performed in pulsed high magnetic fields, where the duration of the pulsed field restricts the available measurement timescale from a few to several hundred milliseconds. We present some successful examples with a focus on the recent technical breakthroughs both in the measurement and magnetic-field generation techniques. These experimental techniques can be used in other experimental conditions in order to increase the signal-to-noise ratio and the repetition rate of time-resolved measurements. Taking the impacts of these applications on current condensed matter research into consideration, we also discuss the future direction of the time-resolved measurement in pulsed magnetic fields.

Publ.-Id: 35066

Fermi surface of the chiral topological semimetal PtGa

Schwarze, B. V.; Uhlarz, M.; Hornung, J.; Chattopadhyay, S.; Manna, K.; Shekhar, C.; Felser, C.; Wosnitza, J.

PtGa is a topological semimetal with giant spin-split Fermi arcs. Here, we report on angular-dependent de Haas–van Alphen (dHvA) measurements combined with band-structure calculations to elucidate the details of the bulk Fermi surface of PtGa. The strong spin–orbit coupling leads to eight bands crossing the Fermi energy that form a multitude of Fermi surfaces with closed extremal orbits and results in very rich dHvA spectra. The large number of experimentally observed dHvA frequencies make the assignment to the equally large number of calculated dHvA orbits challenging. Nevertheless, we find consistency between experiment and calculations verifying the topological character with maximal Chern number of the spin-split Fermi surface.

Publ.-Id: 35065

Ultrahigh transverse thermoelectric power factor in flexible Weyl semimetal WTe2

Pan, Y.; He, B.; Helm, T.; Chen, G.; Schnelle, W.; Felser, C.

Topological semimetals are well known for their interesting physical properties, while their mechanical properties have rarely received attention. With the increasing demand for flexible electronics, we explore the great potential of the van der Waals bonded Weyl semimetal WTe2 for flexible thermoelectric applications. We find that WTe2 single crystals have an ultrahigh Nernst power factor of ~3 Wm−1K−2, which outperforms the conventional Seebeck power factors of the state-of-the-art thermoelectric semiconductors by 2–3 orders of magnitude. A unique band structure that hosts compensated electrons and holes with extremely high mobilities is the primary mechanism for this huge Nernst power factor. Moreover, a large Ettingshausen signal of ~5 × 10−5 KA−1m is observed at 23.1 K and 9 T. In this work, the combination of the exceptional Nernst–Ettingshausen performance and excellent mechanical transformative ability of WTe2 would be instructive for flexible micro-/nano-thermoelectric devices.

Publ.-Id: 35064

Coupled frustrated ferromagnetic and antiferromagnetic quantum spin chains in the quasi-one-dimensional mineral antlerite Cu3SO4(OH)4

Kulbakov, A. A.; Kononenko, D. Y.; Nishimoto, S.; Stahl, Q.; Chakkingal, A. M.; Feig, M.; Gumeniuk, R.; Scurschii, I.; Bhaskaran, L.; Zvyagin, S.; Embs, J. P.; Puente-Orench, I.; Wildes, A.; Geck, J.; Janson, O.; Inosov, D. S.; Peets, D. C.

Magnetic frustration, the competition among exchange interactions, often leads to novel magnetic ground states with unique physical properties which can hinge on details of interactions that are otherwise difficult to observe. Such states are particularly interesting when it is possible to tune the balance among the interactions to access multiple types of magnetic order. We present antlerite Cu3SO4(OH)4 as a potential platform for tuning frustration. Contrary to previous reports, the low-temperature magnetic state of its three-leg zigzag ladders is a quasi-one-dimensional analog of the magnetic state recently proposed to exhibit spinon-magnon mixing in botallackite. Density functional theory calculations indicate that antlerite’s magnetic ground state is exquisitely sensitive to fine details of the atomic positions, with each chain independently on the cusp of a phase transition, indicating an excellent potential for tunability.


Publ.-Id: 35063

Theory of ultrasound propagation in LuCo3 near the low-spin–high-spin crossover

Tereshchenko, A. A.; Ovchinnikov, A. S.; Gorbunov, D.; Neznakhin, D. S.

The possibility of experimental observation of the ultrasonic attenuation in the ferromagnet LuCo3 near the low-spin-high-spin crossover is discussed. We show that ultrasound propagation gives rise to transitions between states of the magnon band due to absorption of phonons, and this process is highly sensitive to the value of magnetization. The high magnetic field, which governs the crossover, alters the ultrasound propagation regime from off-resonant to resonant and we formulate a criterion of the change. Calculated temperature and field dependences of the ultrasonic wave number and attenuation clearly demonstrate anomalies in these characteristics in the vicinity of the crossover at intermediate temperatures far below the Curie temperature.

Publ.-Id: 35062

Orbital-induced crossover of the Fulde-Ferrell-Larkin-Ovchinnikov phase into Abrikosov-like states

Kotte, T.; Kühne, H.; Schlueter, J. A.; Zwicknagl, G.; Wosnitza, J.

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state can emerge in superconductors for which the orbital critical field exceeds the Pauli limit. Here, we present angular-resolved specific-heat data of the quasi-twodimensional organic superconductor κ-(ET)2Cu(NCS)2, with a focus on high fields in the regime of the FFLO transition. For an increasing out-of-plane tilt of the applied magnetic field, which leads to an increase of orbital contributions, we found that the nature of the superconducting transition changes from second to first order and that a further transition appears within the high-field superconducting phase. However, the superconducting state above the Pauli limit is stable for field tilt of several degrees. Since any finite perpendicular component of the magnetic field necessarily leads to quantization of the orbital motion, the resulting vortex lattice states compete with the modulated order parameter of the FFLO state leading to complex high-field superconducting phases. By solving the linearized self-consistency equation within weak-coupling BCS theory, we show that our results are clear experimental evidence of an orbital-induced transformation of the FFLO order parameter into Abrikosov-like states of higher Landau levels.


Publ.-Id: 35061

Magnetic and magnetoelastic properties of Er3Al2

Gorbunov, D.; Palazzese Di Basilio, S.; Ishii, I.; Andreev, A. V.; Sebek, J.; Buturlim, V.; Suzuki, T.; Zherlitsyn, S.; Wosnitza, J.

We report on comprehensive investigations of Er3Al2 exhibiting a number of magnetic states. We observe three spontaneous antiferromagnetic transitions at 10, 14, and 24 K. Furthermore, our high-field magnetization and sound-velocity measurements reveal a number of crystal-electric-field (CEF) transitions. Additionally, the velocity of transverse acoustic waves shows a pronounced softening with decreasing temperature in the paramagnetic state. A CEF model that includes quadrupolar interactions explains the observed magnetic and elastic properties and provides a CEF scheme of Er3Al2. However, to explain some of the observations, a refined, more sophisticated model needs to be developed.


  • Secondary publication expected from 16.08.2023

Publ.-Id: 35060

Importance of valence-band anharmonicity and carrier distribution for third- and fifth-harmonic generation in Si:B pumped with intense terahertz pulses

Meng, F.; Walla, F.; Ul-Islam, Q.; Pashkin, O.; Schneider, H.; Jungemann, C.; Thomson, M. D.; Roskos, H. G.

We observe third-harmonic generation (THG) and fifth-harmonic generation (FHG) of free holes in the valence band of bulk Si:B at cryogenic temperature upon irradiation with intense terahertz pulses from a free-electron laser, polarized along the Γ−X direction. The intensities of both signals increase as a function of pulse energy following power laws with respective exponents of 4.2 and 6.2, larger than the exponents of 3 and 5 expected for xi(3) and xi(5) processes with constant susceptibilities and a fixed number of holes. The larger values are attributed to the increase in the density of mobile holes, which results from impact ionization of boron dopants by thermally activated holes in the electric field of the terahertz pulses as already observed in our studies of THG in Si:B reported in Phys. Rev. B 102, 075205 (2020). We apply Monte Carlo simulations of the nonlinear heavy- and light-hole field response, coupled with a finite-difference time-domain treatment of the pump-pulse propagation in the sample, which reproduce the experimental THG:FHG intensity ratio reasonably well. An analysis of the local response demonstrates that, in our pump regime, the harmonic generation is dominated by the band anharmonicity as opposed to the energy-dependent momentum scattering rates or interband scattering. Comparison with the results of a simple one-dimensional model and scrutiny of the three-dimensional band structure shows that one must account for the extent of the carrier distribution transverse to the Γ−X axis as the anharmonicity grows rapidly away from this axis.

Related publications


  • Secondary publication expected from 23.08.2023

Publ.-Id: 35058

Characterization of microbial communities in sedimentary clays used for deep geological repository

Wei, T.-S.; Matschiavelli, N.; Sushko, V.; Schleicher, A. M. S.; Cherkouk, A.

A deep geological repository (DGR) is a multi-barrier concept that has been a solution to store high-level nuclear waste (HLW). The natural Opalinus clay rocks are one of the candidates for entire DGR due to their unique geochemical features. However, the first direct barrier is bentonites which are the processed clay materials that embed metal containers for HLW. The microbial impact, especially when porewater is introduced into DGR and H2 gas is generated via anoxic corrosion of containers, on these clay barriers remains elusive.
Here, we showed that mineral composition between sandy and shaley Opalinus clays from underground laboratory Mt. Terri were discernible. The microbial diversity of Opalinus clay, together with Calcigel bentonite (CaB) and previously published data from Opalinus porewater and Bavarian bentonite (B25) were significantly distinct principal coordinates analysis. The CaB supported diverse phyla, whereas other communities were dominated by Proteobacteria. Moreover, genus Desulfobacterium (phylum Desulfobacterota) was largely enriched by injecting H2 gas into the porewater communities; however, in the B25 incubated with synthetic Opalinus porewater, genera Desulfosporosinus and Pelotomaculum (phylum Firmicutes) were enriched by H2 gas. Interestingly, the signature of these bacteria was also identified in the sandy clay and CaB communities, indicating that these two communities have the capacity in alleviating H2 pressure accumulated in DGR.
In the future, microcosm setup with porewater and H2 gas will be applied to Opalinus clay and CaB samples with different compacted dry density. The understanding of impact on these clay materials will be achieved via metagenome and geochemical analyses.

Keywords: Bentonite; Opalinus clay; Deep geological repository (DRG); Nuclear waste management; 16S amplicon sequencing

  • Poster
    18th International Symposium on Microbial Ecology, 14.-19.08.2022, Lausanne, Switzerland

Publ.-Id: 35057

Vibrio salinus sp. nov., a marine nitrogen-fixing bacterium isolated from the lagoon sediment of an islet inside an atoll in the western Pacific Ocean

Huang, W.; Wang, L.; Chen, J.; Chen, Y. C.; Wei, T.-S.; Chiang, Y. C.; Wang, P.; Lee, T.; Lin, S.; Huang, L.; Shieh, W. Y. S.

A marine, facultatively anaerobic, nitrogen-fixing bacterium, designated strain DNF-1T, was isolated from the lagoon
sediment of Dongsha Island, Taiwan. Cells grown in broth cultures were Gram-negative rods that were motile by means of
monotrichous flagella. Cells grown on plate medium produced prosthecae and vesicle-like structures. NaCl was required and
optimal growth occurred at about 2–3% NaCl, 25–30 °C and pH 7–8. The strain grew aerobically and was capable of
anaerobic growth by fermenting D-glucose or other carbohydrates as substrate. Both the aerobic and anaerobic growth
could be achieved with NH4Cl as a sole nitrogen source. When N2 served as the sole nitrogen source only anaerobic
growth was observed. Major cellular fatty acids were C14:0, C16:0 and C16:1ω7c, while major polar lipids were
phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content was 42.2 mol% based on the genomic DNA
data. Phylogenetic analyses based on 16S rRNA genes and the housekeeping genes, gapA, pyrH, recA and gyrB, revealed
that the strain formed a distinct lineage at species level in the genus Vibrio of the family Vibrionaceae. These results and
those from genomic, chemotaxonomic and physiological studies strongly support the assignment of a novel Vibrio species.
The name Vibrio salinus sp. nov. is proposed for the novel species, with DNF-1T (= BCRC 81209T = JCM 33626T) as the
type strain. This newly proposed species represents the second example of the genus Vibrio that has been demonstrated to
be capable of anaerobic growth by fixing N2 as the sole nitrogen source

Keywords: Marine bacteria; Multilocus sequence analysis (MLSA); Nitrogen-fixing bacteria; Vibrio; Vibrio salinus; Vibrionaceae


  • Secondary publication expected from 31.07.2023

Publ.-Id: 35056

Development of a neurotensin-derived 68Ga-labeled PET ligand with high in vivo stability for imaging of NTS1 receptor-expressing tumors

Schindler, L.; Moosbauer, J.; Schmidt, D.; Spruss, T.; Grätz, L.; Lüdeke, S.; Hofheinz, F.; Meister, S.; Echtenacher, B.; Bernhardt, G.; Pietzsch, J.; Hellwig, D.; Keller, M.

Overexpression of the neurotensin receptor type 1 (NTS1R), a peptide receptor located at the plasma membrane, was reported for a variety of malignant tumors. Thus, targeting the NTS1R with 18F- or 68Ga- labeled ligands is considered a straight-forward approach towards in vivo im-aging of NTS1R-expressing tumors via positron emission tomography (PET). The development of suitable peptidic NTS1R PET ligands derived from neurotensin is challenging due to proteolytic degradation. In this study, we prepared a series of NTS1R PET ligands based on the C-terminal fragment of neurotensin (NT(8-13), Arg8-Arg9-Pro10-Tyr11-Ile12-Leu13) by attachment of the che-lator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) via an Nω-carbamoylated arginine side chain. Insertion of Ga3+ in the DOTA cage gave potential PET ligands that were evaluated concerning NTS1R affinity (range of Ki values: 1.2-21 nM) and plasma stability. Four candidates were labeled with 68Ga3+ and used for biodistribution studies in HT-29 tumor bearing mice. [68Ga]UR-LS130 ([68Ga]56), containing an N-terminal methyl group and a β,β-dimethylated tyrosine instead of Tyr11, showed the highest in vivo stability and afforded a tumor-to-muscle ratio of 16 at 45 min p.i. Likewise, dynamic PET scans enabled a clear tumor visualization. The accumulation of [68Ga]56 in the tumor was NTS1R mediated as proven by blocking studies.

Publ.-Id: 35055

Structural and Chemical Modifications of Few-layer Transition Metal Phosphorous Trisulfides by Electron Irradiation

Köster, J.; Storm, A.; Ghorbani Asl, M.; Kretschmer, S.; Gorelik, T. E.; Krasheninnikov, A.; Kaiser, U.

Transition metal phosphorous trisulfides (TMPTs) are inorganic materials with inherent magnetic properties. Due to their layered structure, they can be exfoliated into ultra-thin sheets, which show properties different from their bulk counterparts. Herein, we present a detailed analysis of the interaction of the electron beam (30 – 80 kV) in a transmission electron microscope (TEM) with freestanding few-layer TMPTs, with the aim to tailor their properties. The irradiation-induced structure modifications were systematically investigated by various TEM methods on FePS3, MnPS3, and NiPS3, and the results are rationalized with the help of ab-initio calculations, which predict that the knock-on threshold for removing sulfur is significantly lower than that for phosphorus. Therefore, a targeted removal of sulfur is feasible. Eventually, our experiments confirm the dose-dependent, predominantly removal of sulfur by the impinging electrons, thus showing the possibility to tune the sulfur concentration. Using ab-initio calculations, we analyze the electronic structure of the TMPTs with single vacancies and oxygen impurities, and predict distinct electronic properties depending on the type of defect. Therefore, our study shows the possibility of tuning the properties of ultrathin freestanding TMPTs by controlling their stoichiometry.

Keywords: Two-dimensional materials; Transition metal phosphorous trisulfides; Defects; Electron irradiation; Transmission electron microscope; ab-initio calculations

Related publications


  • Secondary publication expected from 01.09.2023

Publ.-Id: 35054

Controlling stoichiometry in ultrathin van der Waals films: PtTe₂, Pt₂Te₃, Pt₃Te₄, and Pt₂Te₂

Lasek, K.; Ghorbani Asl, M.; Pathirage, V.; Krasheninnikov, A.; Batzill, M.

The platinum-tellurium phase diagram exhibits various (meta)stable van der Waals (vdW) materials, that can be constructed by stacking PtTe2 and Pt2Te2 layers. Mono phase PtTe2, being the thermodynamically most stable compound, can readily be grown as thin films. Obtaining the other phases (Pt2Te3, Pt3Te4, Pt2Te2), especially in their ultimate thin form, is significantly more challenging. We show that PtTe2 thin films can be transformed by vacuum annealing-induced Te-loss into Pt3Te4- and Pt2Te2- bilayers. These transformations are characterized by scanning tunneling microscopy, x-ray and angle resolved photoemission spectroscopy. Once Pt3Te4 is formed, it is thermally stable up to 350˚C. To transform Pt3Te4 into Pt2Te2, a higher annealing temperature of 400˚C is required. The experiments combined with density functional theory calculations provide insights into these transformation mechanisms and show that a combination of the thermodynamic preference of Pt3Te4 over a phase segregation into PtTe2 and Pt2Te2 and an increase in the Te-vacancy formation energy for Pt3Te4 compared to the starting PtTe2 material is critical to stabilize the Pt3Te4 bilayer. To desorb more tellurium from Pt3Te4 and transform the material into Pt2Te2, a higher Te-vacancy formation energy has to be overcome by raising the temperature. Interestingly, bilayer Pt2Te2 can be re-tellurized by exposure to Te-vapor. This causes the selective transformation of the topmost Pt2Te2 layer into two layers of PtTe2, and consequently the synthesis of e Pt2Te3. Thus, all known Pt-telluride vdW compounds can be obtained in their ultrathin form by carefully controlling the stoichiometry of the material.

Keywords: van der Waals materials; 2D materials; interlayer interaction; charge transfer; phase stability; platinum telluride; composition control

Related publications


  • Secondary publication expected from 02.06.2023

Publ.-Id: 35053

Fluorination of silyl prosthetic groups by fluorine mediated silyl ether linker cleavage: a concept study with conditions applicable in radiofluorination

Kramer, C. S.; Greiner, L.; Kopka, K.; Schäfer, M.

Background: Positron emission tomography (PET) is a powerful tool in medical imaging, especially in combination with the PET radionuclide fluorine-18 that possesses optimal characteristics. For labelling of biomolecules and low-molecular weight tracers, fluorine-18 can be covalently bound to silicon by either nucleophilic replacements of leaving groups (like ethers) or by isotope exchange of fluorine-19. While nucleophilic substitutions require additional purification steps for the removal of contaminants, isotope exchange with fluorine-18 results in low molar activity. Both challenges can be addressed with a detagging-fluorination of an immobilized silyl ether motif.
Results: By overcoming the susceptibility towards hydrolysis, optimized detagging conditions (improved reaction time, fluorination reagent, linker, and resin) could afford the highly sterically hindered silyl fluoride motifs, that are commonly applied in radiochemistry in small and semipreparative scales. The described reaction conditions with fluorine-19 are transferrable to conditions with [18F]fluoride and silyl fluorides were obtained after approx. 10 min reaction time and in high-purity after mechanical filtration.
Conclusions: We present a proof-of-concept study for a detagging-fluorination of two silyl ethers that are bound to an optimized amino alcohol resin. We show with our model substrate that our solid-phase linker combination is capable of yielding the desired silicon fluoride in amounts sufficient for biological studies in animals or humans under standard fluorination conditions that may also be transferred to a radiolabelling setting. In conclusion, our presented approach could optimize the molar activity and simplify the preparation of radiofluorinated silyl fluorides.

Keywords: Detagging; Fluorine-18; PET; Radiofluorination; SiFA; Silyl fluorides; Solid phase synthesis; Solid support

Publ.-Id: 35052

Covalent Triazine Frameworks and Porous Carbons: Perspective from an Azulene-Based Case

Jiang, K.; Peng, P.; Tranca, D.; Tong, G.; Ke, C.; Lu, C.; Hu, J.; Liang, H.; Li, J.; Zhou, S.; Kymakis, E.; Zhuang, X.

Covalent triazine frameworks (CTFs) are among the most valuable
frameworks owing to many fantastic properties. However, molten
salt-involved preparation of CTFs at 400–600 °C causes debate on whether
CTFs represent organic frameworks or carbon. Herein, new CTFs based on the
1,3-dicyanoazulene monomer (CTF-Azs) are synthesized using molten ZnCl2
at 400–600 °C. Chemical structure analysis reveals that the CTF-Az prepared at
low temperature (400 °C) exhibits polymeric features, whereas those prepared
at high temperatures (600 °C) exhibit typical carbon features. Even after being
treated at even higher temperatures, the CTF-Azs retain their rich porosity, but
the polymeric features vanish. Although structural de-conformation is a widely
accepted outcome in polymer-to-carbon rearrangement processes, the study
evaluates such processes in the context of CTF systems. A proof-of-concept
study is performed, observing that the as-synthesized CTF-Azs exhibit
promising performance as cathodes for Li- and K-ion batteries. Moreover, the
as-prepared NPCs exhibit excellent catalytic oxygen reduction reaction (ORR)
performance; hence, they can be used as air cathodes in Zn-air batteries. This
study not only provides new building blocks for novel CTFs with controllable
polymer/carbon features but also offers insights into the formation and
structure transformation history of CTFs during thermal treatment.


  • Secondary publication expected from 09.06.2023

Publ.-Id: 35051

Towards Tomography-Based Real-Time Control of Multiphase Flows: A Proof of Concept in Inline Fluid Separation

Garcia, M. M.; Sattar, M. A.; Atmani, H.; Legendre, D.; Babout, L.; Schleicher, E.; Hampel, U.; Portela, L. M.

The performance of multiphase flow processes is often determined by the distribution of phases inside the equipment. However, controllers in the field are typically implemented based on flow variables, which are simpler to measure, but indirectly connected to performance (e.g., pressure). Tomography has been used in the study of the distribution of phases of multiphase flows for decades, but only recently, the temporal resolution of the technique was sufficient for real-time reconstructions of the flow. Due to the strong connection between the performance and distribution of phases, it is expected that the introduction of tomography to the real-time control of multiphase flows will lead to substantial improvements in the system performance in relation to the current controllers in the field. This paper uses a gas–liquid inline swirl separator to analyze the possibilities and limitations of tomography-based real-time control of multiphase flow processes. Experiments were performed in the separator using a wire-mesh sensor (WMS) and a high-speed camera to show that multiphase flows have two components in their dynamics: one intrinsic to its nonlinear physics, occurring independent of external process disturbances, and one due to process disturbances (e.g., changes in the flow rates of the installation). Moreover, it is shown that the intrinsic dynamics propagate from upstream to inside the separator and can be used in predictive and feedforward control strategies. In addition to the WMS experiments, a proportional–integral feedback controller based on electrical resistance tomography (ERT) was implemented in the separator, with successful results in relation to the control of the distribution of phases and impact on the performance of the process: the capture of gas was increased from 76% to 93% of the total gas with the tomography-based controller. The results obtained with the inline swirl separator are extended in the perspective of the tomography-based control of quasi-1D multiphase flows.

Keywords: tomography-based control; inline fluid separator; swirl separator; hydrocyclone; gas– liquid swirl flow; electrical resistance tomography; real-time control; multiphase flows

Publ.-Id: 35050

Super-SIMS; Combining a SIMS with AMS – Status of this challenging initiative

Ziegenrücker, R.

Super-SIMS is a project, where a commercial SIMS (Secondary Ion Mass Spectrometer) is used as an ion source for the 6 MV Tandem accelerator at the HZDR's Ion Beam Center. This combination allows the complete suppression of molecular isobaric ions, which are a major challenge for standard SIMS. The presentation gives an overview about the advantages such a device would have and its possible applications.

Keywords: Super-SIMS; Mass spectrometry; Accalerator mass spectrometry; AMS; SIMS; molecular interference

Related publications

  • Invited lecture (Conferences)
    GEOANALYSIS 2022 - Workshop SIMS ANALYSIS, 06.-15.08.2022, Freiberg/Dresden, Deutschland

Publ.-Id: 35049

Quality assurance for chemical databases using the example of the thermodynamic reference database THEREDA

Bok, F.; Moog, H. C.; Gaona, X.; Freyer, D.; Wissmeier, L.

Quality assurance for thermodynamic databases is essential to increase confidence in predictive models based on such data. Demands are numerous and range from the review and selection of data, their correct input into a digital database, internal calculations and conversions, to the output of the data to the users - as formatted- parameter files specific for geochemical modeling programs as well as a display on a website with open access to the public. Both technical procedures and reciprocal audits by the editors are used in this process.
An essential part of data quality checks are comparative calculations against experimental measurements. This is accompanied by internal, automated test calculations before each new data release. Moreover, the uncertainty information is given for all data, which are also evaluated and accordingly labelled in terms of quality using a simple scheme. All this information helps users to evaluate the sensitivity of individual parameters and their influence on the result of geochemical calculations in their work.
Maximum transparency is also intended to demonstrate the trustworthiness of the data: For each datum included, the primary source is given in detail, and the results of all comparative calculations are openly presented on the project website (
The reliability of the database also includes its long-term availability. THEREDA's system is completely based on free and open source software and extended by self-developed, fully documented components. This guarantees independence from software manufacturers and at the same time ensures the future availability of the data.

Keywords: thermodynamic database; THEREDA; quality assurance

  • Invited lecture (Conferences)
    BASE-Workshop „Trust in Models“ (TiM 2022), 17.-18.11.2022, Berlin, Deutschland

Publ.-Id: 35047

Stable Multi-Day Performance of a Laser Wakefield Accelerator for FEL Applications

Couperus Cabadağ, J. P.; Bock, S.; Chang, Y.-Y.; Debus, A.; Gebhardt, R.; Ghaith, A.; Helbig, U.; Irman, A.; Köhler, A.; Laberge, M.; Pausch, R.; Püschel, T.; Schramm, U.; Schöbel, S.; Steiniger, K.; Ufer, P.; Zarini, O.; Roussel, E.; Couprie, M.- . E.; Labat, M.; Downer, M. C.

We report on the operation of the DRACO Laser Driven electron source for stable multi-day operation for Free Electron Laser (FEL) applications. The nC-class accelerator can deliver charge densities around 10 pC/MeV , <1 mrad rms divergence at energies up to 0.5 GeV and peak currents of over 10 kA*.
Precise characterisation is paramount for controlled operation, including: spectrally resolved charge diagnostic, 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 for systematic exploration of demanding applications, resulting in the recent demonstration of the first LWFA based Beam-driven Plasma Wakefield Accelerator (LPWFA)****.
Fulfilling the high demands required for FEL operation, the COXINEL manipulation line***** developed at Synchotron SOLEIL has recently been installed at our facility. Based on successful beam transport of over 13000 shots within 9 experimental days during commissioning, we were able to demonstrate the very first operation of a seeded FEL driven by a laser plasma accelerator******.

* J.P. Couperus et al., Nat. Comm. 8 (2017)
** O. Zarini et al., PRAB (2022)
*** A. Lumpkin et al., Phys. Rev. Lett., 125, 014801 (2020)
**** T. Kurz, T. Heinemann et al., Nature Commun., 12, 2895 (2021)
***** M.-E. Couprie et al., J. Phys B, 47, 234001 (2014) & M.-E. Couprie et al., PPCF, 58, 034020 (2016)
****** M. Labat et al., in review, (2022), doi:10.21203/

Keywords: FEL; LWFA

  • Poster
    FEL conference Trieste (FEL2022), 22.-26.08.2022, Trieste, Italy

Publ.-Id: 35045

Time- and dose-dependent volume decreases in subcortical grey matter structures of glioma patients after radio(chemo)therapy

Raschke, F.; Witzmann, K.; Seidlitz, A.; Wesemann, T.; Jentsch, C.; Platzek, I.; van den Hoff, J.; Kotzerke, J.; Beuthien-Baumann, B.; Baumann, M.; Linn, J.; Krause, M.; Troost, E. G. C.

Background and purpose: Radiotherapy (RT) is an adjuvant treatment option for glioma patients. Side effects include tissue atrophy, which might be a contributing factor to neurocognitive decline after treatment. The goal of this study was to determine potential atrophy of the hippocampus, amygdala, thalamus, putamen, pallidum and caudate nucleus in glioma patients having undergone magnetic resonance imaging (MRI) before and after RT. Materials and methods: Subcortical volumes were measured using T1-weighted MRI from patients before RT (N = 91) and from longitudinal follow-ups acquired in three-monthly intervals (N = 349). The volumes were normalized to the baseline values, while excluding structures touching the clinical target volume (CTV) or abnormal tissue seen on FLAIR imaging. A multivariate linear effects model was used to determine if time after RT and mean RT dose delivered to the corresponding structures were significant predictors of tissue atrophy. Results: The hippocampus, amygdala, thalamus, putamen, and pallidum showed significant atrophy after RT as function of both time after RT and mean RT dose delivered to the corresponding structure. Only the caudate showed no dose or time dependant atrophy. Conversely, the hippocampus was the structure with the highest atrophy rate of 5.2 % after one year and assuming a mean dose of 30 Gy. Conclusion: The hippocampus showed the highest atrophy rates followed by the thalamus and the amygdala. The subcortical structures here found to decrease in volume indicative of radiosensitivity should be the focus of future studies investigating the relationship between neurocognitive decline and RT. © 2022 The Authors

Keywords: Amygdala; Atrophy; Caudate; Hippocampus; Proton therapy; Radiotherapy

Publ.-Id: 35044

Data publication: Electrokinetic Janus micromotors moving on topographically flat chemical patterns

Huang, T.; Misko, V.; Caspari, A.; Synytska, A.; Ibarlucea, B.; Nori, F.; Faßbender, J.; Cuniberti, G.; Makarov, D.; Baraban, L.

Uploaded data show the research discussions of the electroosmotic flows at the boundary between positive and negative surfaces .

Related publications


Publ.-Id: 35042

Comparison of manual and automated ventricle segmentation in the maternal immune stimulation rat model of schizophrenia

Winter, R.; Akinola, B.; Barroeta-Hlusicka, E.; Meister, S.; Pietzsch, J.; Winter, C.; Bernhardt, N.

Maternal immune stimulation (MIS) is strongly implicated in the etiology of neuropsychiatric disorders. Magnetic resonance imaging (MRI) studies provide evidence for brain structural abnormalities in rodents following prenatal exposure to MIS. Reported volumetric changes in adult MIS offspring comprise among others larger ventricular volumes, consistent with alterations found in patients with schizophrenia. Linking rodent models of MIS with non-invasive small animal neuroimaging modalities thus represents a powerful tool for the investigation of structural endophenotypes. Traditionally manual segmentation of regions-of-interest, which is laborious and prone to low intra- and inter-rater reliability, was employed for data analysis. Recently automated analysis platforms in rodent disease models are emerging. However, none of these has been found to reliably detect ventricular volume changes in MIS nor directly compared manual and automated data analysis strategies. The present study was thus conducted to establish an automated, structural analysis method focused on lateral ventricle segmentation. It was applied to ex-vivo rat brain MRI scans. Performance was validated for phenotype induction following MIS and preventive treatment data and compared to manual segmentation. In conclusion, we present an automated analysis platform to investigate ventricular volume alterations in rodent models thereby encouraging their preclinical use in the search for new urgently needed treatments.

Publ.-Id: 35041

Helical dislocations and dislocation line decoration in ion-irradiated Fe-9Cr studied by scanning transmission electron microscopy

Vogel, K.; Engelmann, H.-J.; Chekhonin, P.; Bergner, F.; Kaden, C.

Fe-9Cr is a model alloy for studying irradiation effects that are relevant for potential applications of high-chromium ferritic/martensitic steels in nuclear energy devices. Here we report on scanning transmission electron microscopy (STEM) studies of the microstructure of Fe-9Cr irradiated with 8 MeV Fe3+ ions. Two samples were irradiated with different ion fluences resulting in peak values of displacement damage of 2 and 10 dpa, respectively. The spatial distribution of irradiation-induced dislocation loops was studied with special emphasis on the effects of pre-existing network dislocations.
The most striking feature of the irradiated microstructure is the presence of helical dislocations. From comparison of the irradiated layer with the dislocation arrangement in the non-irradiated substrate it is concluded that the helices were formed from straight pre-existing line dislocations that originally had a dominating screw component. Other types of dislocations observed in the material did not adopt a helical shape during irradiation. Decreasing the dose has a significant effect on the helical dislocations, the helices are less developed and have a smaller diameter. For both irradiation conditions, an inhomogeneous distribution of irradiation-induced dislocation loops is observed. A high number of loops is present close to the helical dislocations and also close to dislocations that have not adopted a helical shape. In areas away from the dislocations, the number of visible loops is very low.
The loop clustering close to helical dislocations resembles observations reported for neutron irradiated Fe-9Cr. Hence we conclude that ion irradiations can produce similar defect configurations like neutron irradiations when the arrangement of pre-existing dislocations is comparable.

Keywords: irradiation-induced defects; helical dislocations; dislocation loops; ion-irradiated Fe-Cr; scanning TEM

Related publications

  • Poster
    Nuclear Materials Conference 2022, 24.-28.10.2022, Ghent, Belgium

Publ.-Id: 35040

Electrokinetic Janus micromotors moving on topographically flat chemical patterns

Huang, T.; Misko, V.; Caspari, A.; Synytska, A.; Ibarlucea, B.; Nori, F.; Faßbender, J.; Cuniberti, G.; Makarov, D.; Baraban, L.

Ionic and molecular selectivity are considered unique for the nanoscale and not realizable in microfluidics. This is due to the scale-matching problem – a difficulty to match the dimensions of ions and electrostatic potential screening lengths with micron-sized confinements. Here, we demonstrate a microscale realization of ionic transport processes closely resembling those specific to ionic channels or in nanofluidic junctions, including selectivity, guidance and flow focusing. As a model system, we explore electrokinetic spherical Janus micromotors moving over charged surfaces with complex charge distribution and without any topographical wall. We discuss peculiarities of the long-range electrostatic interaction on the behavior of the system including interface crossing and reflection of positively charged particles from negatively charged interfaces. These results are crucial for understanding the electrokinetic transport of biochemical species under confinement, have the potential to increase the precision of lab-on-chip-based assays, as well as broadening use cases and control strategies of nano-/micromachinery.

Publ.-Id: 35039

Resummation for quantum propagators in bounded spaces

Edwards, J. P.; González-Domínguez, V. A.; Huet, I.; Trejo Espinosa, M. A.

We outline an approach to calculating the quantum mechanical propagator in the presence of geometrically nontrivial Dirichlet boundary conditions. The method is based on a generalization of an integral transform of the propagator studied in previous work (the so-called “hit function”) and a convergent sequence of Padé approximants that exposes the limit of perfectly reflecting boundaries. In this paper the generalized hit function is defined as a many-point propagator, and we describe its relation to the sum over trajectories in the Feynman path integral. We then show how it can be used to calculate the Feynman propagator. We calculate analytically all such hit functions in D = 1 and D = 3 dimensions, giving recursion relations between them in the same or different dimensions and apply the results to the simple cases of propagation in the presence of perfectly conducting planar and spherical plates. We use these results to conjecture a general analytical formula for the propagator when Dirichlet boundary conditions are present in a given geometry, also explaining how it can be extended for application for more general, nonlocalized potentials. Our work has resonance with previous results obtained by Grosche in the study of path integrals in the presence of delta potentials. We indicate the eventual application in a relativistic context to determining Casimir energies using this technique.

Keywords: Integral equations; Quantum theory; Bounded spaces; Convergent sequences; Dirichlet boundary conditions; Feynman path integrals; Generalisation; Integral transform; Pade approximants; Quantum mechanical; Reflecting boundary; Resummation


Publ.-Id: 35038

Enhanced Longitudinal Relaxation of Magnetic Solitons in Ultrathin Films

Yastremsky, I. A.; Faßbender, J.; Ivanov, B. A.; Makarov, D.

Relaxation fundamentally determines the operation speed and energy efficiency of spintronic and
spinorbitronic devices. We develop a theory of the longitudinal contribution to the relaxation of domain
walls in ferromagnetic films of any thickness with the Dzyaloshinskii-Moriya interaction, which allows
quantitative comparison with experiments. We show that the longitudinal contribution increases with a
decrease of the transversal relaxation (e.g., the Gilbert constant). We predict a substantial enhancement
of the contribution of the longitudinal relaxation to the damping of magnetic solitons with a decrease of
the film thickness. We demonstrate that for ultrathin ferromagnetic films, the contribution of the longitudinal
relaxation to the damping of domain walls is comparable to or stronger than any other traditional
transversal mechanisms, including spin pumping. Although in this work we focus on the analysis of longitudinal
relaxation for domain walls, in ultrathin samples it should be taken into account also for other
magnetic solitons including skyrmions. This work adds to the fundamental understanding of the design
and optimization of spintronic and spinorbitronic devices based on moving solitons in ultrathin films.

Keywords: Longitudinal Relaxation; magnetic thin films; magnetic solitons


Publ.-Id: 35037

Modification of Porous Ultralow‑k Film by Vacuum Ultraviolet Emission

Zotovich, A. I.; Zyryanov, S. M.; Lopaev, D. V.; Rezvanov, A. A.; Attallah, A. G.; Liedke, M. O.; Butterling, M.; Bogdanova, M. A.; Vishnevskiy, A. S.; Seregin, D. S.; Vorotyntsev, D. A. V.; Palov, A. P.; Hirschmann, E.; Wagner, A.; Naumov, S.; Vorotilov, K. A.; Rakhimova, T. V.; Rakhimov, A. T. R.; Baklanov, M.

Modification of spin-on-deposited porous PMO
(periodic mesoporous organosilica) ultralow-k (ULK) SiCOH
films (k = 2.33) containing both methyl terminal and methylene
bridging groups by vacuum ultraviolet (VUV) emission from Xe
plasma is studied. The temporal evolution of chemical composition,
internal defects, and morphological properties (pore structure
transformation) is studied by using Fourier transform infrared
spectroscopy, in situ laser ellipsometry, spectroscopic ellipsometry,
ellipsometric porosimetry (EP), positron-annihilation lifetime
spectroscopy (PALS), and Doppler broadening positron-annihilation spectroscopy. Application of the different advanced diagnostics
allows making conclusions on the dynamics of the chemical composition and pore structure. The time frame of the VUV exposure in
the current investigation can be divided into two phases. During the first short phase, film loses almost all of its surface methyl and
matrix bridging groups. An increase of material porosity due to removal of methyl groups with simultaneous matrix shrinkage is
found by in situ ellipsometry. The removal of bridging bonds leads to an increase of matrix intrinsic porosity. Nevertheless, when the
treated material is exposed to the ambient air, the sizes of micro- and mesopores and pores interconnectivity decrease with the VUV
exposure time according to PAS and EP data. The last is the result of the additional film shrinkage caused by atmosphere exposure.
During the second phase the increase of mesopore size is detected by both EP and PAS. The increase of mesopore size goes all the
time as it is expected from in situ ellipsometry, but it is masked by the air exposure

Keywords: ultralow-k materials; vacuum ultraviolet emission; porosimetry; positron-annihilation spectroscopy; in situ ellipsometry

Publ.-Id: 35036

Laser-generated supersonic plasma jets and shocks in a transverse magnetic field

Bohlin, H.; Brack, F.-E.; Cervenak, M.; Chodukowski, T.; Cikhardt, J.; Dostál, J.; Dudžák, R.; Hubner, J.; Huo, W.; Jelinek, S.; Klír, D.; Kroll, F.; Krupka, M.; Krůs, M.; Pisarczyk, T.; Rusiniak, Z.; Schramm, U.; T.-H, N.-B.; Weber, S.; Zaraś-Szydłowska, A.; Zeil, K.; Kumar, D.; Schlegel, T.; Tikhonchuk, V.

The influence of a transverse magnetic field on the formation and evolution of supersonic plasma jets and shocks was studied experimentally, and compared with 3D numerical simulations. An improved jet collimation was seen due to the change in the magnetic field topology restricting the radial expansion of the ablated plasma. The magnetic field was also shown to strongly affect the shock structures, both indirectly through the modified jet geometry, as well as due to a compression of the field lines in the shock region. The interaction characteristics were found to depend on the relative contribution of the magnetic and plasma pressure in balancing the ram pressure of the jet.

Keywords: Laser; Plasma; Astrophysics; Pulsed Magnet

Publ.-Id: 35035

Transient CFD Calculation of Accretion Formation in a Copper Waste Heat Boiler

Schmidt, A.; Montenegro, V.; Reuter, M.; Charitos, A.; Stelter, M.; Richter, A.

The operation of a copper Flash Smelting Furnace (FSF) is often limited by the availability of the downstream Waste Heat Boiler (WHB). Carry-over of concentrate into the boiler leads to accretion formation, which can cause boiler downtime. Hence, the minimization of flue dust and its accretions is an important operational goal. In this study, a Computational Fluid Dynamics (CFD) model is used to investigate how three different baffle plate designs influence accretion formation over a period of 24h. The predicted dust accretion patterns were compared for all baffle plate modifications, with differences found both in the resulting sedimentation and accretion of dust particles. While the dispersive design led to large, but evenly coated accretion risk zones, a streamlined design minimized their size, but led to locally thick accretion layers. Based on these findings, design recommendations for the baffle plate were derived.

Keywords: Flash Smelting Furnace; Waste Heat Boiler; Flue Dust; Dust Accretions; CFD

Publ.-Id: 35032

Numerical modeling of horizontal stratified two-phase flows using the AIAD model

Yan, H.; Zhang, H.; Höhne, T.; Liao, Y.; Lucas, D.; Liu, L.

In nuclear reactor safety research, the countercurrent gas-liquid two-phase flow in the hot leg of a pressurized water reactor (PWR) has attracted considerable attention. Previous work has proven that the algebraic interfacial area density (AIAD) model implemented in ANSYS CFX can effectively capture the gas-liquid interface and avoid the loss of information regarding the interfacial structure, which occurs after phase averaging in the Euler–Euler two-fluid approach. To verify the accuracy of the AIAD module implementation in ANSYS Fluent, the model based on the experimental data from the WENKA facility is validated in this work. The effects of the subgrid wave turbulence model, turbulence damping model, and droplet entrainment model are simultaneously investigated, which have been shown to be important in the previous work with CFX. The results show that the simulations are considerably and significantly deviate from the experiments when the turbulence damping is not considered. The free surface modeling of two-phase flow can be optimized by using the droplet entrainment model. The consistency between the simulation and experimental results is not enhanced after the subgrid wave turbulence model is adopted. Further investigations regarding the implementation of the subgrid wave turbulence model are necessary.

Keywords: AIAD; CFD; droplet entrainment; subgrid wave turbulence; thermal hydraulics; turbulence damping

Publ.-Id: 35031

Understanding structure–properties relationships of porphyrin linked to graphene oxide through π–π-stacking or covalent amide bonds

Lewandowska-Andralojc, A.; Gacka, E.; Pedzinski, T.; Burdzinski, G.; Lindner, A. A.; O’Brien, J. M.; Senge, M. O.; Siklitskaya, A.; Kubas, A. G.; Marciniak, B.; Walkowiak-Kulikowska, J.

Two graphene oxide nanoassemblies using 5-(4-(aminophenyl)-10,15,20-triphenylporphyrin
(TPPNH2) were fabricated by two synthetic methods: covalent (GO-CONHTPP) and noncovalent
bonding. GO-CONHTPP was achieved through amide formation at the periphery of GO sheets and the
hybrid material was fully characterized by FTIR, XPS, Raman spectroscopy, and SEM. Spectroscopic
measurements together with theoretical calculations demonstrated that assembling TPPNH2
on the GO surface in DMF-H2O (1:2, v/v) via non-covalent interactions causes changes in the absorption
spectra of porphyrin, as well as efficient quenching of its emission. Interestingly, covalent binding
to GO does not affect notably neither the porphyrin absorption nor its fluorescence. Theoretical
calculations indicates that close proximity and π–π-stacking of the porphyrin molecule with the GO
sheet is possible only for the non-covalent functionalization. Femtosecond pump–probe experiments
revealed that only the non-covalent assembly of TPPNH2 and GO enhances the efficiency of the
photoinduced electron transfer from porphyrin to GO. In contrast to the non-covalent hybrid,
the covalent GO-CONHTPP material can generate singlet oxygen with quantum yields efficiency
(ΦΔ = 0.20) comparable to that of free TPPNH2 (ΦΔ = 0.26), indicating the possible use of covalent
hybrid materials in photodynamic/photothermal therapy. The spectroscopic studies combined with
detailed quantum-chemical analysis provide invaluable information that can guide the fabrication of
hybrid materials with desired properties for specific applications.

Keywords: porphyrin; graphene oxide; photochemistry

Publ.-Id: 35030

Ressourceneffizienzsteigerung in der Metallindustrie - Substitution von Primärrohstoffen durch optimiertes legierungsspezifisches Recycling

Raatz, S.; Seidel, P.; Tuma, A.; Thorenz, A.; Helbig, C.; Reller, A.; Faulstich, M.; Joachimsthaler, C.; Steger, S.; Hagedorn, W.; Bickel, M.; Liedtke, C.

Das durch das Umweltbundesamt geförderte Projekt befasst sich mit der Ressourceneffizienz-
steigerung in der Metallindustrie in Hinblick auf die Substitution von Primärrohstoffen, die im
Recyclingprozess zur Verdünnung unerwünschter Begleitelemente beim Recycling eine wesent-
liche Rolle spielen. Das damit einhergehend Downcycling soll mittels innovativer Sortiertechni-
ken (Kamera-/Sensorsysteme) vermindert und der Recyclingprozess von metallischen Legie-
rungen durch eine höhere Trennschärfe deutlich verbessert werden.
Der Fokus der Untersuchungen liegt in diesem Projekt auf der Untersuchung eines legierungs-
spezifischen Recyclings von Stahl-, Aluminium-, Kupfer- und Zinkschrotten. Hier soll der Ver-
gleich verschiedener Schrottfraktionen vor bzw. nach innovativen Analyse- bzw. Sortier- und Se-
parier-Prozessen neue Erkenntnisse liefern. Darüber hinaus werden definitorische Grundlagen
sowie Steuerungsgrößen für Up- und Downcycling und Regeln für sortenarmes Design erarbei-
Auf Grundlage der Analyseergebnisse werden politische Empfehlungen zur besseren Erschlie-
ßung bisher nicht genutzter, hochwertiger Metallpotenziale erarbeitet. Zu den Bewertungsmaß-
stäben gehören die Einsparpotenziale von primären Rohstoffen und damit Treibhausgasemissio-
nen sowie die Kostenstruktur für die Herstellung von möglichst hochwertigen Legierungen aus
Eine erfolgreiche, das heißt mit minimalen Downcycling-Prozessen „belastete“ Bereitstellung
von sekundären Rohstoffen erfordert eine umfassende Wissensbasis über die wissenschaftli-
chen Hintergründe von Downcycling, bestehende Recyclingstrukturen und verwendete Sortier-
techniken, technologische Potenziale, metallurgische Prozesssimulationen und Bewertungsan-
sätzen von Recyclingprozessen, die im Rahmen dieses Projektes entwickelt und genutzt werden.

Keywords: Metallwirtschaft; OptiMet; Ressourceneffizienz; Downcycling; Sortierung; Recycling; Legierung; Sortiertechnologien; LIBS; XRT; XRF; NAA

  • Open Access Logo Other report
    06844 Dessau-Roßlau: Umweltbundesamt, 2022
    354 Seiten

Publ.-Id: 35029

A terminology for downcycling

Raatz, S.; Huether, J.; Joachimsthaler, C.; Lehmann, C.; Helbig, C.; Thorenz, A.; Faulstich, M.; Tuma, A.

The term downcycling is often used anecdotally to describe imperfections in recycling. However, it is rarely defined. Here, we identify six meanings of the term downcycling as used in scientific articles and reports. These encompass the material quality of reprocessed materials, target applications, product value, alloying element losses, material systems, and additional primary production. In a proposal for harmonized and more specific terminology, we define downcycling as the phenomenon of quality reduction of materials reprocessed from waste relative to their original quality. We further identify that the reduced quality can express itself thermodynamically, functionally, and economically, covering all perspectives on downcycling. Dilution, contamination, reduced demand for recycled materials, and design-related issues can cause those downcycling effects. We anticipate that this more precise terminology can help quantify downcycling, keep materials in the loop longer, use materials more often and at higher quality, and therefore assist in reducing material-related environmental impacts.

Keywords: circular economy; downcycling; downgrading; industrial ecology; recycling; waste

Publ.-Id: 35028

Electrical Conductivity of Iron in Earth’s Core from Microscopic Ohm’s Law (SCCS 22)

Lokamani, M.; Vorberger, J.; Cangi, A.; Baczewski, A.; Ramakrishna, K.

Understanding the electronic transport properties of iron under high temperatures and pressures is essential for constraining geophysical processes. The difficulty of reliably measuring these properties under for sophisticated theoretical methods that can support diagnostics. We present results of the electrical conductivity from simulating microscopic Ohm’s law using time-dependent density functional theory.

Keywords: TDDFT; Matter under Extreme Conditions; Computational Physics; Ab-initio methods

  • Lecture (Conference)
    Strongly Coupled Coulomb Systems (SCCS) 2022, 25.07.2022, Görlitz, Germany

Publ.-Id: 35027

Steps towards Reliable Data - Basic Tools and Concepts

Pospiech, S.

Uncertainties in geochemical data can have many different sources. The previous workshop sections focused on the definitions of data reliability, uncertainties and errors, and how these can be calculated. In this part of the workshop, we will discuss how (hidden) uncertainties in data and errors in geochemical analyses can be detected during data handling, what measures help to minimize uncertainties and errors, and how to deal with the errors that arise to obtain data with high reliability. Simple but effective tools will be presented using a sample snow data set.

Keywords: workshop; geoanalsysis 2022; uncertainty; data reliability; snow

  • Lecture (Conference)
    Geoanalysis 2022, 06.-12.08.2022, Freiberg, Germany

Publ.-Id: 35026

Cosmic nucleosynthesis: A multi-messenger challenge

Diehl, R.; Korn, A. J.; Leibundgut, B.; Lugaro, M.; Wallner, A.

The origins of the elements and isotopes of cosmic material is a critical aspect of understanding the evolution of the universe. Nucleosynthesis typically requires physical conditions of high temperatures and densities. These are found in the Big Bang, in the interiors of stars, and in explosions with their compressional shocks and high neutrino and neutron fluxes. Many different tools are available to disentangle the composition of cosmic matter, in material of extraterrestrial origins such as cosmic rays, meteorites, stardust grains, lunar and terrestrial sediments, and through astronomical observations across the electromagnetic spectrum. Understanding cosmic abundances and their evolution requires combining such measurements with approaches of astrophysical, nuclear theories and laboratory experiments, and exploiting additional cosmic messengers, such as neutrinos and gravitational waves. Recent years have seen significant progress in almost all these fields; they are presented in this review.

The Sun and the solar system are our reference system for abundances of elements and isotopes. Many direct and indirect methods are employed to establish a refined abundance record from the time when the Sun and the Earth were formed. Indications for nucleosynthesis in the local environment when the Sun was formed are derived from meteoritic material and inclusion of radioactive atoms in deep-sea sediments. Spectroscopy at many wavelengths and the neutrino flux from the hydrogen fusion processes in the Sun have established a refined model of how the nuclear energy production shapes stars. Models are required to explore nuclear fusion of heavier elements. These stellar evolution calculations have been confirmed by observations of nucleosynthesis products in the ejecta of stars and supernovae, as captured by stardust grains and by characteristic lines in spectra seen from these objects. One of the successes has been to directly observe
rays from radioactive material synthesised in stellar explosions, which fully support the astrophysical models. Another has been the observation of radioactive afterglow and characteristic heavy-element spectrum from a neutron-star merger, confirming the neutron rich environments encountered in such rare explosions. The ejecta material captured by Earth over millions of years in sediments and identified through characteristic radio-isotopes suggests that nearby nucleosynthesis occurred in recent history, with further indications for sites of specific nucleosynthesis. Together with stardust and diffuse gamma-rays from radioactive ejecta, these help to piece together how cosmic materials are transported in interstellar space and re-cycled into and between generations of stars. Our description of cosmic compositional evolution needs such observational support, as it rests on several assumptions that appear challenged by recent recognition of violent events being common during evolution of a galaxy. This overview presents the flow of cosmic matter and the various sites of nucleosynthesis, as understood from combining many techniques and observations, towards the current knowledge of how the universe is enriched with elements.

Keywords: Nuclear Astrophysics; Nucleosynthesis; Stars; Supernovae; Interstellar medium; Stardust; accelerator mass spectrometry


Publ.-Id: 35025

The recovery effects of electron-beam pulse treatment in Sn implanted Ge

Werner, Z.; Barlak, M.; Ratajaczak, R.; Kentsch, U.; Heller, R.; Munnik, F.; Konarski, P.; Dłużewski, P.; Pisarek, M.; Kozłowski, M.; Ażgin, J.; Zagórski, J.; Staszkiewicz, B.

The paper describes the recovery effects of pulsed electron beam treatment in Ge single crystals implanted with various doses of Sn ions at room and low temperatures. A protective coat of 100 nm Sn was applied as a sacrificial layer. The implanted layers were studied by RBS/cRBS (Rutherford BackScattering/channeled Rutherford BackScattering) method, SIMS (Secondary Ion Mass Spectrometry) and TEM (Transmission Electron Microscopy). Defects revealed in channelled RBS spectra were analysed by McChasy code. The results show that the Sn concentration attains 1% and more with very good substitutionality. They also reveal excellent lattice recovery after e-beam melting. Suggestions are derived as regards further improvement of pulsed e-beam technique.

Keywords: Germanium; Sn implantation; pulsed e-beam treatments; RBS/cRBS study; TEM and DLTS measurements

Related publications

Publ.-Id: 35024

Non-van der Waals quasi-2D materials; recent advances in synthesis, emergent properties and applications

Balan, A. P.; Puthirath, A. B.; Roy, S.; Costin, G.; Oliveira, E. F.; Saadi, M. A. S. R.; Sreepal, V.; Friedrich, R.; Serles, P.; Biswas, A.; Iyengar, S. A.; Chakingal, N.; Bhattacharyya, S.; Saju, S. K.; Pardo, S. C.; Sassi, L. M.; Filleter, T.; Krasheninnikov, A.; Galvao, D. S.; Vajtai, R.; Nair, R. R.; Ajayan, P. M.

The discovery of novel materials that are stable at ambient conditions with emergent functionalities is a pressing need of the
21st century to keep the pace of social and technological advancement in a sustainable manner. Nanotechnology and
nanomaterials are one of this kind and the current era has already witnessed several groundbreaking discoveries of
materials and disruptive technological advancements. Starting from 0D fullerene, the invention of 1D carbon nanotubes, and
most recently 2D graphene, all are allotropes of carbon, have brought a lot of research opportunities to understand different
physical and chemical phenomena at atomic and molecular scales and to convert such properties into useful applications.
Among them, 2D materials find special attention due to unique properties such as ballistic carrier transport, immunity from
substrate effects and commendable in plane mechanical robustness. However, the library of such materials is limited, and
one can see that most of the technically viable materials that are already industrialized in a large scale belong to the class of
non-van der Waals materials. The effect of confinement in one dimension on non-van der Waals materials remains
unexplored owing to the difficulty in fabricating these materials to the ultra-thin limit with large lateral size or area. Recent
advancement of cleaving non-van der Waals bulk materials to their ultra-thin counter parts through the state-of-the-art liquid
phase exfoliation approach leads to renewed research interest among scientific community. The existence of
cleaving/parting planes in certain directions of non-van der Waals materials, where the bonding strength is relatively weak
compared to other crystallographic directions of the bulk crystal, facilitate smooth exfoliation when subjected to shear force
through suitable methods. Herein, we attempt to discuss the rationale of such methods in the synthesis of non-van der
Waals 2D materials that possess cleavage/parting planes with a special attention to natural ores, and to review the recent
progress made in non-van der Waals two-dimensional materials with a special emphasis on emergent magnetism, catalysis,
energy storage, and optoelectronics and related applications.

Keywords: 2D magnetism; 2D materials; Catalysis; Non-van der Waals materials; Photodetectors; Tribology

Related publications


Publ.-Id: 35023

Experimental Study on Inter-Bubble Distances in Dense Bubbly Flows

Kipping, R.; Hampel, U.

The design of bubble column reactors require a comprehensive understanding of the fluid dynamics. The type of gas distributor has a main impact on bubble size distribution and flow regime. With increasing gas flow rate, the interaction of the bubble increases and the dispersion of the bubbles changes. Although these effects play an important role also on the mass transfer in bubble columns, the distance parameters of bubbles in dense swarms has been poorly investigated so far.

This contribution presents an experimental study carried out with ultrafast X-ray CT (UFXCT) on a dense bubbly flow. Experiments were conducted in a bubble column of 10 cm inner diameter and for gas superficial velocities up to 3.5 cms-1. UFXCT allows for non-invasive plane measurement of the phase distribution at different scanning heights of the column. Based on the extracted coordinates of the bubble centers the distances of nearest neighbors of all bubbles were computed. In addition, pair correlation function has been applied to reveal information on the near order of bubbles. The Sauter Mean Diameter was found to have a remarkable influence on the clustering characteristics and the near order of the bubbles.

  • Lecture (Conference) (Online presentation)
    15th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering (GLS-15), 07.-10.08.2022, Ottawa, Canada

Publ.-Id: 35022

Tailored engineering of crystalline surface enabled by ion-irradiation-assisted femtosecond laser ablation

Ren, Y.; Wang, C.; Cui, Z.; Liu, H.; Han, X.; Liu, P.; Akhmadaliev, S.; Zhou, S.; Cai, Y.

Ion irradiation and femtosecond laser ablation (FLA) are powerful technologies for micro-/nano-machining of transparent materials. In this work, we demonstrate selective surface engineering of optical crystal surface via ion irradiation and subsequent FLA, namely ion-irradiation-assisted FLA. Based on the material modification effects in the ion-irradiated layers, different types of surface structuring characterized by grooves, nanogratings or sub-micron tracks are selectively induced by FLA. It is revealed that the ion-electron interaction induced localized lattice defects and related property modulation in target crystal play important roles in the formation and evolution of laser ablation regimes. Furthermore, the formation process of high-spatial-frequency nanograting is illustrated with the periodical enhancement of local field through the excitation of surface plasmon polaritons, which is experimentally supported through the measurements of transmission electron microscope and energy-dispersive spectroscopy. Our findings further clarify the ion- and laser-matter interactions and the correlation between these processes and surface modifications. The approach proposed in this work shows potential applications in the rapid fabrication of hybrid and versatile surface structures on crystalline materials.

Related publications


  • Secondary publication expected from 15.07.2023

Publ.-Id: 35021

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