Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The development of lateral heterostructures (LHs) based on two- dimensional (2D) materials with similar atomic structure but distinct electronic properties, such as transition metal dichalcogenides (TMDCs), opened a new route towards realisation of optoelectronic devices with unique characteristics. In contrast to van der Waals vertical heterostructures, the covalent bonding at the interface between subsystems in LHs is strong, so that the morphology of the interface, which can be coherent or contain dislocations, strongly a↵ects the properties of the LH. We predict the atomic structure of the interface with account for the mismatch between the primitive cell sizes of the components, and more important, the widths of the joined materials using parameters derived from first-principles calculations. We apply this approach to a variety of TMDCs and set a theoretical limit on when the transition of the interface from coherent to dislocation-type should occur. We validate our theoretical results by comparison with the initial stage of two-dimensional heteropitaxial growth of junctions between MoS2 and TaS2 on Au(111).

This talk will present our research on merging machine learning with quantum mechanics. Electron-nuclear interactions determine all materials' properties, and accurate simulations of electronic structure are essential to address critical scientific questions related to renewable energy, sustainable materials, and semiconductor devices. However, electronic structure simulations face an accuracy-size tradeoff.
I will first present our ongoing efforts on developing the Materials Learning Algorithms (MALA) package to solve the electronic structure problem faster. MALA leverages a combination of neural networks, physically constrained optimization algorithms, and efficient post-processing routines. Next, I will present our work on using physics-informed neural networks to solve the time-dependent Kohn-Sham equations, which describe electron dynamics in response to incident electromagnetic waves.

Interactions between electrons and nuclei in matter determine all materials' properties. Understanding and modeling these interactions is of paramount importance, particularly in addressing critical scientific questions related to renewable energy solutions, sustainable materials, and semiconductor device modeling. However, simulations of the electronic structure face a common constraint—an accuracy-size tradeoff. While it is possible to simulate materials at the quantum level of accuracy, this is typically limited to a few thousand atoms, even with advanced tools like density functional theory (DFT). On the other hand, large-scale simulations often sacrifice predictive power due to necessary approximations.
The Materials Learning Algorithms (MALA) [1] package addresses these challenges by leveraging a combination of neural networks, physically constrained optimization algorithms [2], and efficient post-processing routines. Unlike existing approaches, MALA replaces DFT entirely, providing access to both scalar quantities of interest, such as energies, and volumetric information about the electronic structure, such as the electronic density. Our research has demonstrated that MALA can be applied to systems with arbitrary numbers of atoms (successfully testing up to 100,000 atoms) [3], across various temperature and pressure ranges [4]. We anticipate that MALA will have a significant impact, enabling unprecedented modeling capabilities in the fields of materials science and semiconductor device modeling.

[1] L. Fiedler, Z. A. Moldabekov, X. Shao, K. Jiang, T. Dornheim, M. Pavanello, A. Cangi, Phys. Rev. Res. 4, 043033 (2022).
[2] L. Fiedler, N. Hoffmann, P. Mohammed, G. A. Popoola, T. Yovell, V. Oles, J. A. Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol. 3, 045008 (2022).
[3] L. Fiedler, N. A. Modine, S. Schmerler, D. J. Vogel, G. A. Popoola, A. P. Thompson, S. Rajamanickam, A. Cangi, Npj Comput. Mater. 9, 115 (2023).
[4] L. Fiedler, N. A. Modine, K. D. Miller, A. Cangi, arXiv:2306.06032 (2023).

Machine learning has emerged as a powerful technique for processing large and complex datasets. Recently it has been utilized for both improving the accuracy and accelerating the computational speed of electronic structure theory. In this chapter, we provide the theoretical background of both density functional theory, the most widely used electronic structure method, and machine learning on a generally accessible level. We provide a brief overview of the most impactful results in recent times. We, further, showcase how machine learning is used to advance static and dynamic electronic structure calculations with concrete examples. This chapter highlights that fusing concepts of machine learning and density functional theory holds the promise to greatly advance electronic structure calculations enabling unprecedented applications for in-silico materials discovery and the search for novel chemical reaction pathways.

Within cosmology, there are two entirely independent pillars which can jointly drive this field towards precision: Astronomical observations of primordial element abundances and the detailed surveying of the cosmic microwave background. However, the comparatively large uncertainty stemming from the nuclear physics input is currently still hindering this effort, i.e. stemming from the 2H(p,γ)3He reaction. An accurate understanding of this reaction is required for precision data on primordial nucleosynthesis and an independent determination of the cosmological baryon density.
Elsewhere, our Sun is an exceptional object to study stellar physics in general. While we are now able to measure solar neutrinos live on earth, there is a lack of knowledge regarding theoretical predictions of solar neutrino fluxes due to the limited precision (again) stemming from nuclear reactions, i.e. from the 3He(α,γ)7Be reaction. This thesis sheds light on these two nuclear reactions, which both limit our understanding of the universe. While the investigation of the 2H(p,γ)3He reaction will focus on the determination of its cross- section in the vicinity of the Gamow window for the Big Bang nucleosynthesis, the main aim for the 3He(α,γ)7Be reaction will be a measurement of its γ-ray angular distribution at astrophysically relevant energies.
In addition, the installation of an ultra-low background counting setup will be reported which further enables the investigation of the physics of rare events. This is essential for modern nuclear astrophysics, but also relevant for double beta decay physics and the search for dark matter. The presented setup is now the most sensitive in Germany and among the most sensitive ones worldwide.

AiiDA is an open-source Python infrastructure for devising complex workflows associated with modern computational science and streamlining the four core pillars of the ADES model: Automation, Data, Environment, and Sharing. In this contribution, we showcase features of AiiDA like workflow-forging, high-throughput capability and data provenance as implemented in the AiiDA-FLEUR plugin. Finally, we address the possibility of managing AiiDA-projects through HELIPORT.

Two-dimensional (2D) materials are traditionally derived from bulk layered compounds bonded by weak
van der Waals (vdW) forces. In this context, the recent surprising experimental realization of non-vdW
2D compounds obtained from non-layered crystals [1,2] foreshadows a new direction in 2D systems
research. These materials are distinct from traditional 2D sheets as their surface was revealed to be
terminated by cations rather than anions.
Here, we present several dozens of candidates of this novel materials class derived from applying data-driven
research methodologies in conjunction with autonomous ab initio calculations and also outline
how to tune their properties [3,4]. We find that the oxidation state of the surface cations of the
2D sheets is an enabling descriptor regarding the manufacturing of these systems as it determines their
exfoliation energy: small oxidation states promote easy peel off [3]. When extending the set from oxides
to sulfides and chlorides, the exfoliation energy becomes ultra low due to strong surface relaxations [4].
The materials also pass several tests validating their vibrational and dynamic stability. The candidates
exhibit a wide range of appealing electronic, optical and magnetic properties which can be tuned by proper
chemical functionalization of the 2D sheets making these systems an attractive platform for fundamental
and applied nanoscience.
References
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] A. Puthirath Balan et al., Chem. Mater. 30, 5923 (2018).
[3] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[4] T. Barnowsky et al., Adv. Electron. Mater. 2201112 (2023).

Background
Focal adhesion signaling networks involving receptor tyrosine kinases (RTK) and integrins control central aspects of cancer cell survival and therapy resistance. However, co-dependencies between these transmembrane receptors and therapeutically exploitable vulnerabilities remain largely elusive in HPV-negative head and neck squamous cell carcinoma (HNSCC).
Methods
The cytotoxic and radiochemosensitizing potential of targeting 10 RTK and β1 integrin were determined in up to 20 different 3D matrix-grown HNSCC cell models. RNA sequencing and protein‑based biochemical assays were performed for molecular and pathway characterization. Bioinformatically identified transcriptomic signatures were applied to patient cohorts to show clinical relevance.
Results
Our findings indicate that fibroblast growth factor receptors (FGFR 1-4) present with the strongest cytotoxic and radiosensitizing potential, both as a monotherapy and when combined with β1 integrin inhibition, surpassing the efficacy of the other assessed RTKs. Pharmacological pan-FGFR inhibition induced a variable response spectrum ranging from cytotoxicity/radiochemosensitization to resistance/radioprotection. The latter prompted us to perform RNA sequencing analysis revealing an association of these contrasting responses to pan-FGFR inhibition with a mesenchymal-to-epithelial (MET) transition for sensitive cell models, whereas resistant cell models exhibited a partial epithelial-to-mesenchymal transition (EMT). In line, inhibition of EMT-associated kinases such as EGFR, PKC and PAK proved effective in reducing the adaptive FGFR-driven resistance. Finally, the translation of the transcriptomic profiles associated with EMT to HNSCC patient cohorts not only demonstrated its prognostic value but also provided conclusive validation of the presence of EMT-related vulnerabilities that can be strategically harnessed for therapeutic intervention.
Conclusions
This study demonstrates that pan-FGFR inhibition elicits both a highly beneficial radiochemosensitizing and a detrimental radioprotective potential in HNSCC cell models. Adaptive EMT-associated resistance appears to be of clinical importance, and we provide effective molecular approaches to exploit this therapeutically.

Despite the success of chimeric antigen receptor (CAR) T-cells especially for treating hematological malignancies, critical drawbacks, such as “on-target, off-tumor” toxicities, need to be addressed to improve safety in translating to clinical application. This is especially true, when targeting tumor-associated antigens (TAAs) that are not exclusively expressed by solid tumors but also on healthy tissues. To improve the safety profile, we developed switchable adaptor CAR systems including the RevCAR system. RevCAR T-cells are activated by cross-linking of bifunctional adaptor molecules termed target modules (RevTM). In a further development, we established a Dual-RevCAR system for an AND-gated combinatorial targeting by splitting the stimulatory and co-stimulatory signals of the RevCAR T-cells on two individual CARs. Examples of common markers for colorectal cancer (CRC) are the carcinoembryonic antigen (CEA) and the epithelial cell adhesion molecule (EpCAM), while these antigens are also expressed by healthy cells. Here we describe four novel structurally different RevTMs for targeting of CEA and EpCAM. All anti-CEA and anti-EpCAM RevTMs were validated and the simultaneous targeting of CEA+ and EpCAM+ cancer cells redirected specific in vitro and in vivo killing by Dual-RevCAR T-cells. In summary, we describe the development of CEA and EpCAM specific adaptor RevTMs for monospecific and AND-gated targeting of CRC cells via the RevCAR platform as an improved approach to increase tumor specificity and safety of CAR T-cell therapies.

Background: Programmed cell death ligand 1 (PD-L1) plays a critical role in the tumor microenvironment and overexpression in several solid cancers has been reported. This was associated with a downregulation of the local immune response, specifically of T-cells. Immune checkpoint inhibitors have the potential to reactivate the immune system, but only 30% of patients are considered responders. New diagnostic approaches re therefore needed to determine patient eligibility. Small molecule radiotracers targeting PD-L1 may serve as such diagnostic tools, addressing the heterogeneous PD-L1 expression between and within tumor lesions, thus aiding in therapy decisions. Results: Four small-molecule biphenyl-based PD-L1 ligands were synthesized using a convergent synthetic route with a linear sequence of up to eleven steps. Three different chelators (NODA-GA, CB-TE2A, DiAmSar) were employed to efficiently radiolabel these compounds with copper-64, and a dimeric structure was also synthesized. All radioligands exhibited high proteolytic stability (>95%) for 48 hours post-radiolabeling. Saturation binding yielded moderate affinities ranging from 100 to 265 nM. Conversely, real-time radioligand binding revealed more promising KD values of about 20 nM for [64Cu]Cu-14 and [64Cu]Cu-15. In vivo PET imaging in mice bearing PC3 PD-L1 overexpressing and PD-L1-negative tumors was performed at 0–2, 4–5 and 24–25 h post injection (p.i.). This revealed considerably different pharmacokinetic profiles, depending on the substituted chelator. [64Cu]Cu-14, substituted with NODA-GA, showed renal clearance with low liver uptake, whereas substitution with the cross-bridged cyclam chelator CB-TE2A resulted in a primarily hepatobiliary clearance. Notably, the monomeric DiAmSar radioligand [64Cu]Cu-16 demonstrated a higher liver uptake than [64Cu]Cu-15, but was still renally cleared as evidenced by the lack uptake in gall bladder and intestines. The dimeric structure [64Cu]Cu-17 showed extensive accumulation and trapping in the liver but was also cleared via the renal pathway. After 24 h post-injection, [64Cu]Cu-17 showed the highest accumulation in the PD-L1-overexpressing tumor of all timepoints and all radiotracers, indicating drastically increased circulation time upon dimerization of two PD-L1 binding motifs. Conclusions: This study with biphenyl-based small molecule PD-L1 radioligands clearly shows that the chelator choice significantly influences the pharmacokinetic profile. The NODA-GA-conjugated radioligand [64Cu]Cu-14 exhibited favorable renal clearance; however, the limited uptake in tumors suggests the need for structural modifications to the binding motif for future PD-L1 radiotracers.

Ni-doped Mn5Si3 alloys of nominal compositions Mn_5-xNi_xSi₃ (for x = 0.05, 0.1, and 0.2) have been investigated through detailed neutron powder diffraction (NPD) studies in zero magnetic field and ambient pressure. At room temperature, all three Ni-doped alloys crystallize with D8₈ type hexagonal structure having P6₃∕mcm space group. These alloys undergo paramagnetic → collinear antiferromagnetic → non-collinear antiferromagnetic transitions on cooling from room temperature. A significant decrease in collinear to non-collinear antiferromagnetic transition temperature has been observed with increasing Ni concentration. The magnetic structure of both antiferromagnetic phases can be described by the magnetic propagation vector k = (0,1,0). However, the moment size and the orientation in the non-collinear antiferromagnetic phase are found to be notably affected by the Ni-doping. Approaching near-parallel arrangement of Mn-moments with increasing Ni-doping is found to be responsible for the gradual disappearance of unusual magnetic properties (inverted hysteresis loop, thermomagnetic irreversibility, etc.) observed in Mn₅Si₃ alloy.

We studied magnetic states and phase transitions in the van der Waals antiferromagnet VBr₃ experimentally by specific heat and magnetization measurements of single crystals in high magnetic fields and theoretically by the density functional theory calculations focused on exchange interactions. The magnetization behavior mimics Ising antiferromagnets with magnetic moments pointing out-of-plane due to strong uniaxial magnetocrystalline anisotropy. The out-of-plane magnetic field induces a spin-flip metamagnetic transition of first-order type at low temperatures, while at higher temperatures, the transition becomes continuous. The first-order and continuous transition segments in the field-temperature phase diagram meet at a tricritical point. The magnetization response to the in-plane field manifests a continuous spin canting which is completed at the anisotropy field μ₀H_MA ≈ 27 T. At higher fields, the two magnetization curves above saturate at the same value of magnetic moment μ_sat ≈ 1.2 μ_B/f.u., which is much smaller than the spin-only (S = 1) moment of the V³⁺ ion. The reduced moment can be explained by the existence of an unquenched orbital magnetic moment antiparallel to the spin. The orbital moment is a key ingredient of a mechanism responsible for the observed large anisotropy. The exact energy evaluation of possible magnetic structures shows that the intralayer zigzag antiferromagnetic (AFM) order is preferred, which renders the AFM ground state significantly more stable against the spin-flip transition than the other options. The calculations also predict that a minimal distortion of the Br ion sublattice causes a radical change of the orbital occupation in the ground state, connected with the formation of the orbital moment and the stability of magnetic order.

In this paper, we investigate the physical properties of the type-II multiferroic GdMn₂O₅ material by means of neutron scattering, electric polarization, and magnetization measurements. A complex (T,H) phase diagram shows up, with especially a field-induced magnetic transition around 11 T at low temperature. The high-field phase is accompanied by an additional electric polarization along both the a and b directions, as authorized by symmetry, but never observed experimentally up to now. While the magnetic properties recover their initial states after driving the field back to zero, the polarization along a shows a significant increase. This behavior is observed for all directions of the magnetic field. It constitutes a novel and striking manifestation of the magnetoelectric coupling, resulting in the establishment of a new ground state at zero magnetic field.

Foam processes are essential in many industrial applications e.g., in froth flotation for material
separation. A detailed understanding of foam flows is vital for improvements in process efficiency. X-
Ray and Neutron imaging can measure flow fields in foam, but require a complex setup and cannot be
performed in-situ. Magnetic particle tracking (MPT) is an alternative approach, that measures the
trajectory of a small magnetic tracer particle inside the foam as a representation of its movement.
Different magnetic field sensors can be applied to detect the magnetic tracer particle. We chose thin film
sensors based on the planar Hall effect (PHE) due to their small size, high sensitivity, high signal-to-
noise ratio and low cost. Our sensors have a size of only 2 mm x 2 mm and are capable of measuring
magnetic fields as low as 10 nT at a sampling frequency of 1 Hz. A sensitivity of 20 V/T at a driving
current of 1 mA was achieved by means of sensor bridging. Our PHE-sensors are almost as precise as
currently used Fluxgate probes, but offer several advantages due to their reduced size. This includes
being installed closer to the area to be measured, enabling finer grids of sensors and decreasing the
detection volume, which increases the precision of the MPT as well as other tomographic methods.

In this paper we report on an experimental study focusing on the manifestation and dynamics of the large-scale circulation (LSC) in turbulent liquid metal convection. The experiments are performed inside a cylinder of aspect ratio Γ = 0.5 filled with the ternary alloy GaInSn, which has a Prandtl number of Pr = 0.03. The large-scale flow structures are classified and characterized at Rayleigh numbers of Ra = 9.33×10⁶ , 5.31×10₇ and 6.02×10₈ by means of the contactless inductive flow tomography (CIFT) which enables the full reconstruction of the three-dimensional flow structures in the entire convection cell. This is complemented with the multi-thermal-probe method for capturing the azimuthal temperature variation induced by the LSC at the sidewall. We use proper orthogonal decomposition (POD) to identify the dominating modes of the turbulent convection. The analysis reveals that a single-roll structure (SRS) of the LSC alternates in short succession with double-roll structures (DRS) or a three-roll structure (TRS). This is accompanied by dramatic fluctuations of the Reynolds number, whose instantaneous values can deviate by more than 50% from the time-average value. No coherent oscillations are observed, whereas a correlation analysis indicates a residual contribution of the torsion and sloshing modes. Results of the POD analysis suggest a stabilisation of the single-roll LSC with increasing Ra at the expense of flow structures with multiple rolls. Moreover, the relative lifetime of all identified flow states, measured in units of free-fall times, increases with rising Ra.

Digital holographic reconstruction has been a challenging task for many years due to its strict
requirements of prior knowledge of experimental setups as well as additional filtering algorithms
to suppress the zeroth-order light and twin image problems. Inspired by the data-driven
deep learning method, which is directly able to learn the non-linearity mapping between two
variables, a variety of research has been done in this area by pioneers. However, previous
methods are mainly constrained to discriminative models and they ignore the ill-posed nature
of holographic reconstruction. To address this problem, in this work, we define a novel variant
of normalizing flow, named conditional Wavelet Flow (cWavelet Flow), to reconstruct original
real space structures from digital X-ray holograms with a high degree of generative diversity
and quality. To pave the ground for the construction of cWavelet Flow, we first reproduce the
architecture and part of the experimental results of Wavelet Flow [2] based on PyTorch and
then extend it as cWavelet Flow by attaching an additional conditioning network on top of it.
The conditioning network, which consists of an optional pre-trained backbone network and a
head network, is constructed as an exceptionally lightweight yet performant structure. Such an
architectural design allows cWavelet Flow to directly model the conditional data distribution
of high resolution up to 1024 × 1024, which is almost impossible with the flow-based models
developed previously. Furthermore, another appealing point of cWavelet Flow is its highly
efficient training process. In comparison to other state-of-the-art baseline models like cINN
and U-Net, an improvement of up to 11.5× and 126.2× fewer FLOPs are achieved, respectively,
while maintaining reconstruction quality comparable to these baseline models.

More than half of all energy converted by humankind is lost in the form of waste heat. Not only
does that strongly contribute to the acceleration of global warming [1], it also leaves an enormous
economic potential untouched. However, suitable technologies are limited [2], since most
of this heat is of low temperature (< 100 °C) [3] and low grade. In the last years, materials and
technologies for thermoelectric harvesting and thermomagnetic harvesting have been explored,
but reaching a high efficiency of those systems remains a challenge. With our work, we present
a thermoelastic harvesting approach for converting the waste heat of a fluid into electricity,
utilizing Nickel-Titanium wires. The inherent advantage of a higher material efficiency than
thermoelectrics [4,5], together with the possibility to adapt the wires to the desired temperature
range via alloying and prestrain, and the commercial availability of the material makes NiTi a
solid candidate for a waste heat harvesting system. The core structure of our harvesting system
is a newly developed design for a fluid chamber. With the use of coupled FEM-Simulations we
optimized the heat exchange process between a thermal fluid and the wire and therefore maximized
the thermodynamic efficiency of the thermal energy to mechanical energy conversion
(32 % of Carnot). In this work, we show our approach in optimizing the heat exchange between
the fluid and the wire and the influence of parameters, like preload and waste heat temperature,
on the efficiency of the system.

Electric-field control of magnetism via an inverse magnetostrictive effect is an alternative path toward improving energy-efficient storage and sensing devices based on a giant magnetoresistance effect. In this Letter, we report on lateral electric-field driven strain-mediated modulation of magnetotransport properties in a Co/Cu/Py pseudo spin valve grown on a ferroelectric 0.7Pb[Mg1/3Nb2/3]O3–0.3PbTiO3 substrate. We show a decrease in the giant magnetoresistance ratio of the pseudo spin valve with the increase in the electric field, which is attributed to the deviation of the Co layer magnetization from the initial direction due to strain-induced magnetoelastic anisotropy contribution. Additionally, we demonstrate that strain-induced magnetic anisotropy effectively shifts the switching field of the magnetostrictive Co layer, while keeping the switching field of the nearly zero-magnetostrictive Py layer unaffected due to its negligible magnetostriction. We argue that magnetostrictively optimized magnetic films in properly engineered multilayered structures can offer a path to enhancing the selective magnetic switching in spintronic devices.

Autonomous flying robots, such as multirotors, often rely on deep learning models that makes predictions based on a camera image, e.g. for pose estimation. These models can predict surprising results if applied to input images outside the training domain. This fault can be exploited by adversarial attacks, for example, by computing small images, so-called adversarial patches, that can be placed in the environment to manipulate the neural network's prediction. We introduce flying adversarial patches, where multiple images are mounted on at least one other flying robot and therefore can be placed anywhere in the field of view of a victim multirotor. By introducing the attacker robots, the system is extended to an adversarial multi-robot system. For an effective attack, we compare three methods that simultaneously optimize multiple adversarial patches and their position in the input image. We show that our methods scale well with the number of adversarial patches. Moreover, we demonstrate physical flights with two robots, where we employ a novel attack policy that uses the computed adversarial patches to kidnap a robot that was supposed to follow a human.

We present a portable multiplexed biosensor platform based on the extended gate field-effect transistor and demonstrate its amplified response thanks to gold nanoparticle-based bioconjugates introduced as a part of the immunoassay. The platform comprises a disposable chip hosting an array of 32 extended gate electrodes, a readout module based on a single transistor operating in constant charge mode, and a multiplexer to scan sensing electrodes one-by-one. Although employing only off-the-shelf electronic components, our platform achieves sensitivities comparable to fully customized nanofabricated potentiometric sensors. In particular, it reaches a detection limit of 0.2 fM for the pure molecular assay when sensing horseradish peroxidase-linked secondary antibody (∼0.4 nM reached by standard microplate methods). Furthermore, with the gold nanoparticle bioconjugation format, we demonstrate ca. 5-fold amplification of the potentiometric response compared to a pure molecular assay, at the detection limit of 13.3 fM. Finally, we elaborate on the mechanism of this amplification and propose that nanoparticle-mediated disruption of the diffusion barrier layer is the main contributor to the potentiometric signal enhancement. These results show the great potential of our portable, sensitive, and cost-efficient biosensor for multidimensional diagnostics in the clinical and laboratory settings, including e.g., serological tests or pathogen screening.

Froth flotation is one of the most important techniques in the mining industry to efficiently separate particles with sizes between 10 μm and 200 μm. The particles are separated according to their difference in wettability, as hydrophobic particles attach to gas bubbles and are recovered in a froth, whereas hydrophilic particles tend to stay in the pulp. Although, the wettability is the most prominent separation feature, other particle properties, such as size, morphology, surface energy or the dispersion state also affect the separation process since it includes a number of complex micro processes with specific particle-bubble interactions that occur in the pulp and in the froth phase. 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”, investigates 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). A well-characterised model particle system, consisting of glass spheres and glass fragments as the floatable fraction and magnetite as the non-floatable fraction is used for the separation tests. 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.

Froth flotation is one of the most important beneficiation techniques in the mining industry. For particles with sizes ranging from 10 μm to 200 μm it efficiently separates the valuable minerals from unwanted gangue according to their differences in the particle wettabilities. For an efficient flotation separation of ultrafine particles (< 10 μm) existing techniques need to be adapted and improved in order to maintain an efficient separation. Furthermore, there is a potential in separating particles not only by wettability (surface energy) and size but also by their morphology. To investigate this is the aim of this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”. A well-characterised model particle system consisting of ultrafine size fractions of glass particles as the floatable and magnetite as the non-floatable fraction 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. All separation tests are carried out in batch mode using a novel separation 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 tromp maps. This investigation will help to further understand the recovery of particles with variable properties in flotation, as well as other separation processes. In this way, the separation of ultrafine particles will become more efficient, which will play an important role in the recycling of secondary materials and in the processing of ultrafine particles in the chemical industry.

Presentation on the recycling of graphite from spent lithium ion batteries, including the characterization of surface properties that are important for the separation process of flotation, by which the graphite is separated effectively from the remaining metal oxides.

Presentation about Li-ion battery characterization with a focus on the characterization of the anode and cathode active materials using different techniques such as inverse gas chromatography, dynamic vapour sorption, contact angle measurement.

Background: Chimeric antigen receptor (CAR) T-cells are a promising approach in cancer immunotherapy, particularly for treating hematologic malignancies. Yet, their effectiveness is limited when tackling solid tumors, where immune cell infiltration and immunosuppressive tumor microenvironments (TME) are major hurdles. Fibroblast activation protein (FAP) is highly expressed on cancer-associated fibroblasts (CAFs) and various tumor cells, playing an important role in tumor growth and immunosuppression. Aiming to modulate the TME with increased clinical safety and effectiveness, we developed novel small and size-extended immunotheranostic UniCAR target modules (TMs) targeting FAP.
Methods: The specific binding and functionality of the anti-FAP-scFv TM and the size extended anti-FAP-IgG4 TM were assessed using 2D and 3D in vitro models as well as in vivo. Their specific tumor accumulation and diagnostic potential was evaluated using PET studies after functionalization with a chelator and suitable radionuclide.
Results: The anti-FAP-scFv and -IgG4 TMs effectively and specifically redirected UniCAR T-cells using 2D, 3D, and in vivo models. Moreover, a remarkably high and specific accumulation of radiolabeled FAP-targeting TMs at the tumor site of xenograft mouse models was observed.
Conclusions: These findings demonstrate that the novel anti-FAP TMs are promising immunotheranostic tools to foster cancer imaging and treatment, paving the way for a more convenient, individualized, and safer treatment of cancer patients.

Examining the Nonlinear Response of Quantum Electrons with the Assistance of Wigner Distribution Function

Zhandos Moldabekov

z.moldabekov@hzdr.de

Center of Advanced Systems Understanding at Helmholtz-Zentrum Dresden-Rossendorf, Germany

A linear response of quantum electrons is well studied and for that well developed theoretical and computational methods computing the linear response properties are available. However, recent introduction of THz lasers and the novel seeding technique to reach high intensities [1] allow us to generate nonlinear response of quantum electrons in extended systems. Therefore, in this talk the results will be presented for the non-linear density response of quantum electrons and the applicability of various approximations and methods for extended systems will be discussed [3-5]. The utility of the quantum Wigner distribution function for the analytic solution of the non-linear response problem of arbitrary order will be presented [5].

[1] B.K. Ofori-Okai, et al., J. Inst13, P06014 (2018).
[2] T Kluge, et al., Phys. Rev. X 8, 031068 (2018).
[3] Z. Moldabekov, Jan Vorberger, and Tobias Dornheim, Journal of Chemical Theory and Computation 18, 2900–2912 (2022).
[4] T.Dornheim, M. Boehme, Z. Moldabekov, J. Vorberger, and M. Bonitz, Phys. Rev. Research 3, 033231 (2021).
[5] P. Tolias, T. Dornheim, Z. Moldabekov, and J. Vorberger, EPL 142 , 44001 (2023).

High bandwidth instruments (data production rates of GB/s) have proliferated in photon science experimental facilities in the last years across the globe. Some of them are planned to be operated 24/7. Data volumes thus produced exceed both the budget of storage facilities and sometimes even the ingest capacities of hardware. In this talk, I'd like to highlight key challenges when considering both lossless and lossy compression in photon science. I will highlight data science approaches to characterize or preprocess data. The talk will also showcase advances in finding optimal encoding parameters to achieve high data ingest bandwidths at high compression ratios. In addition, I'd like to introduce challenges for lossy compression with respect to good scientific practice and our advances to mitigate them without regressing to data quality metrics.

The presentation was given at the 2023 European HDF User Group (HUG) plugins and data compression summit. For more information on the event, see https://indico.desy.de/event/39343/

Electron dynamics of anatase TiO2 under the influence of ultrashort and intense laser field is studied using the real-time time-dependent density functional theory (TDDFT). Our findings demonstrate the effectiveness of TDDFT calculations in modeling the electron dynamics of solids during ultrashort laser excitation, providing valuable insights for designing and optimizing nonlinear photonic devices. We analyze the perturbative and non-perturbative responses of TiO2 to 30 fs laser pulses at 400 and 800 nm wavelengths, elucidating the underlying mechanisms. At 400 nm, ionization via single photon absorption dominates, even at very low intensities. At 800 nm, we observe ionization through two-photon absorption within the intensity range of 1×1010 to 9×1012 W/cm2, with a transition from multiphoton to tunneling ionization occurring at 9×1012 W/cm2. We observe a sudden increase in energy and the number of excited electrons beyond 1×1013 W/cm2, leading to their saturation and subsequent laser-induced damage. We estimate the damage threshold of TiO2 for 800 nm to be 0.1 J/cm2. In the perturbative regime, induced currents exhibit a phase shift proportional to the peak intensity of the laser pulse. This phase shift is attributed to the intensity-dependent changes in the number of free carriers, indicative of the optical Kerr effect. Leveraging the linear dependence of phase shift on peak intensities, we estimate the nonlinear refractive index (n2) of TiO2 to be 3.54×10−11 cm2/W.

Practical 30min guide into ASL basics and its use in clinics and clinical research with focus given on the most important guidelines for practical use.

Bacterial strains that are resistant to antibiotics may protect not only themselves, but also sensitive bacteria nearby if resistance involves antibiotic degradation. Such cross-protection poses a challenge to effective antibiotic therapy by enhancing the long-term survival of bacterial infections. In this study, we utilize an automated nanoliter droplet analyzer to study the interactions between Escherichia coli strains expressing a β-lactamase (resistant) and those not expressing it (sensitive) when exposed to the β-lactam antibiotic cefotaxime (CTX), with the aim to define criteria contributing to cross-protection. We observed a cross-protection window of CTX concentrations for the sensitive strain, extending up to approximately 100 times its minimal inhibitory concentration (MIC). Through both microscopy and enzyme activity analyses, we demonstrate that filamentation of bacterial cells, triggered by antibiotic stress contributes to cross-protection through increased extracellular β-lactamase activity, resulting from cell lysis and/or β-lactamase leakage due to greater cell wall permeability. The antibiotic concentration window for cross-protection depends on the difference in β-lactamase activity between co-cultured strains: larger differences shift the ‘cross-protection window’ towards higher CTX concentrations. Our findings highlight the crucial role of bacterial filamentation in community-wide antibiotic resistance and emphasize the need for intervention therapies that consider -and potentially suppress- filamentation

Atmospheric water harvesting with metal-organic frameworks (MOFs) is a new technology
providing clean, long-term water supply in arid areas. In situ positron annihilation lifetime
spectroscopy (PALS) is proposed as a valid methodology for mechanistic understanding of water
sorption in MOFs and the selection of prospective candidates for desired applications. DUT-67-Zr
and DUT-67-Hf frameworks are used as model systems for method validation because of their
hierarchical pore structure, high adsorption capacity and chemical stability. Both frameworks are
characterized using complementary techniques such as nitrogen (77 K) and water vapour (298 K)
physisorption, SEM, and PXRD. DUT-67-Zr and DUT-67-Hf are investigated by PALS upon
exposure to humidity for the first time, demonstrating the stepwise pore filling mechanism by
water molecules for both MOFs. In addition to exploring the potential of PALS as a tool for
probing MOFs during in situ water loading, this work offers perspectives on the design and use of
MOFs for water harvesting.

Bubble coalescence affects the interphase heat and mass transfer by changing the interfacial area of gas and liquid phases. The coalescence time and liquid film thickness are important physical parameters to describe the bubble coalescence process. When simulating the bubble coalescence with volume of fluid(VOF) method, reasonable settings of adjustable parameters(such as mesh size, maximum Courant number and equation cycle
times, etc.) can improve the convergence of the solution and save the computational time. The aim of this paper is to investigate the coalescence process of two coaxial bubbles combining the VOF method with the adaptive mesh refinement technology based on OpenFOAM. The influence of the maximum Courant number Comax, the cycle times of phase equation nα and the cycle times of governing equation npimple on the computational efficiency and accuracy of numerical simulation of bubble coalescence process was explored. Meanwhile, the time evolution of the liquid film thickness among bubbles was obtained for different adjustable parameters. The results show that the thinning speed of the liquid film between two bubbles is proportional to nα and npimple, while is inversely proportional to Comax. This is because the computational accuracy is promoted by the decrease of Comax and the increase of nα and npimple. The transport lag of the fluid on the grid element is therefore improved, and the bubble coalescence and liquid film thinning is accelerated. Considering the computational accuracy and cost, a set of better adjustable parameters for simulating bubble coalescence with VOF method is obtained, i. e., (Comax, nα,npimple)=(0.05, 3, 8).

The aim of this retrospective multicenter study was an independent validation of a gene expression signature ECM-related prognostic and predictive indicator (EPPI) and the novel positron emission tomography (PET) parameter tumor asphericity (ASP) in non-small cell lung cancer (NSCLC) patients. The whole cohort comprised 253 NSCLC patients, all treated with surgery. Clinical and PET parameters were available for all patients, additional gene expression data for 120 patients. Univariate and multivariate Cox regression and Kaplan-Meier analyses were calculated for progression-free survival (PFS).
A significant association with PFS was observed for ASP (p < 0.001) and EPPI (p = 0.012). Upon multivariate testing, ASP was significantly associated with PFS (p = 0.012), and EPPI (p = 0.018) in patients with additional gene data. In stage II patients, ASP was significantly associated with PFS (p = 0.009) and a previously published cutoff value for ASP (19.5%) was successfully validated (p = 0.008). EPPI showed a significant association with PFS in stage II patients, too (p = 0.033). Exploratory combination of ASP and EPPI showed potentially improved stratification.
We report the first successful validation of EPPI and ASP in stage II NSCLC patients, combination of both parameters seems encouraging.

The higher beam intensity available for Mu2e-II will require a substantially different target design. This paper discusses our recent advances in conceptual R&D for a Mu2e-II target station. The design is based on energy deposition and radiation damage simulations, as well as thermal and mechanical analyses, to estimate the survivability of the system. We considered rotated targets, fixed granular targets and a novel conveyor target with tungsten or carbon spherical elements that are circulated through the beam path. The motion of the spheres can be generated either mechanically or both mechanically and by a He gas flow. The simulations identified the conveyor target as the preferred approach, and that approach has been developed into a prototype. We describe this first prototype for the Mu2e-II target and report on its mechanical tests performed at Fermilab, which indicate the feasibility of the design, and discuss its challenges as well as suggest directions for further improvement.

We present two types of pump-probe spectroscopy on single core-shell III-V nanowires: while the pump is either interband or intraband, a broad-band mid-infrared beam is used as probe. This provides interesting insight into carrier heating and relaxation.

During marine oxygen isotope stage (MIS) 2, the Swiss Plateau temporarily hosted large piedmont lobe glaciers that retreated after their maximum advance back to the fringe of the Alps. The presence of moraines in this region indicates that overall glacier recession was punctuated by repeated phases of ice-marginal stability and re-advances. The timing of these events in the region formerly covered by the eastern lobe of the Rhône (or Valais) glacier has been controversial but remains poorly constrained due to the lack of chronological data. To fill this gap, 10Be cosmic-ray exposure (CRE) dating was applied to erratic boulders inside the assumed MIS 2 maximum extent of this piedmont lobe. Erratic boulders close to the suspected MIS 2 maximum extent gave unrealistically young CRE ages. Erratic boulders at a presumably younger ice-marginal position (Brästenberg position) yielded an average age of ~19 ka, consistent with recalibrated basal radiocarbon ages from lakes and recomputed radiocarbon ages from large Late Pleistocene mammals buried in glacio-fluvial deposits. However, several erratic boulders beyond the Brästenberg position gave internally consistent, but stratigraphically too young ages of ~17 ka. We cannot rule out that glacier recession from the Brästenberg position began no later than ~17 ka. CRE dating of a moraine of a presumably younger ice-marginal position (Solothurn position) gave unrealistically old ages and an incredibly young age (86 ka, 41 ka, and 4 ka). 14C CRE dating should be applied to check whether the boulders associated with the Solothurn and Brästenberg positions were previously exposed to cosmicradiation. Nevertheless, despite outlying ages, the presented chronological data contribute to an overall consistent and increasingly refined chronology of the last deglaciation of the Swiss Plateau when compared with 59 previously published CRE ages.

The importance of methanol as a basic building block of the chemical industry and as a means of chemical energy storage of renewable energy sources (e.g. wind & PV) will steadily increase in the upcoming years. Based on renewable electricity and through the coupling of a proton-conducting steam electrolyzer for the generation of pure H2 with a heterogeneously catalyzed direct synthesis of methanol from anthropogenic CO2, an attractive method for the production of methanol can be provided. To enable an efficient and economic application of these so-called power-to-methanol processes, high system efficiencies as well as suitable concepts for system control as well as system and heat integration for alternating operating conditions are of particular importance. In this work, a transient and real-time capable system model of a power-to-methanol process based on tubular proton-conducting high temperature electrolyzers is presented. The obtained stationary simulation results reveal beneficial operational windows and system efficiencies (0.488 to 0.617) with respect to the chosen process design and heat integration concept. The power-to-methanol process model also incorporates a multitude of feedback control loops or controllers, to manipulate relevant operating parameters of all employed sub-processes in case of fluctuating power inputs. The presented studies assess the transient responses of the modeled power-to-methanol system to defined step changes of the apparent cell voltage under negative feedback control of crucial operational parameters.

Introduction: Loss of blood-brain barrier (BBB) integrity is hypothesized to be one of the earliest microvascular signs of Alzheimer’s disease (AD). Arterial spin labeling (ASL) perfusion MRI has recently been adapted to map the BBB permeability non-invasively. This article outlines the study design of the DEveloping BBB-ASL as a non-Invasive Early biomarker (DEBBIE) consortium, focused on investigating the potential of BBB-ASL as an early biomarker for AD (DEBBIE-AD).
Methods: DEBBIE-AD consists of 13 cohorts enrolling participants from subjective cognitive decline to AD, as well as healthy controls across the lifespan. The reproducibility and accuracy of BBB-ASL will be evaluated in healthy participants, and its clinical value will be evaluated with both established and novel AD biomarkers.
Expected endpoints: DEBBIE-AD aims to provide evidence on the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD-related pathologies, which may provide new targets for treatment.

Semiconductor spin qubits combine excellent quantum performance with the prospect of manufacturing quantum devices using industry-standard metal-oxide-semiconductor (MOS) processes. This applies also to ion-implanted donor spins, which further afford exceptional coherence times and large Hilbert space dimension in their nuclear spin. Here we demonstrate and integrate multiple strategies to manufacture scale-up donor-based quantum computers. We use 31PF2 molecule implants to triple the placement certainty compared to 31P ions, while attaining 99.99% confidence in detecting the implant. Similar confidence is retained by implanting heavier atoms such as 123Sb and 209Bi, which represent high-dimensional qudits for quantum information processing, while Sb2 molecules enable deterministic formation of closely-spaced qudits. We demonstrate the deterministic formation of regular arrays of donor atoms with 300 nm spacing, using step-and-repeat implantation through a nano aperture. These methods cover the full gamut of technological requirements for the construction of donor-based quantum computers in silicon.

Software developed in the process of doing research is receiving increased attention. It is now more and more often considered a genuine research output next to scientific articles and research data publications. Based on representative user stories we identify and characterize the different phases and stages that the research software development process can go through thereby defining the “Research Software Lifecycle”. Different approaches to software development such as product-, project- or platform-orientation are also outlined. We close with recommendations on EOSC infrastructure components needed to support the identified processes and platforms.

Software developed in the process of doing research is receiving increased attention. It is now more and more often considered a genuine research output next to scientific articles and research data publications. Based on representative user stories we identify and characterize the different phases and stages that the research software development process can go through thereby defining the “Research Software Lifecycle”. Different approaches to software development such as product-, project- or platform-orientation are also outlined. We close with recommendations on EOSC infrastructure components needed to support the identified processes and platforms.

Recently, an innovative heat dissipation technique of fractal-tree structures has attracted attention due to its excellent high heat transfer efficiency and low pumping power. Though the impact of geometrical parameters such as branching level and dimension ratios of successive branches on the heat transfer efficiency and pumping power are considered to be critical, the impact mechanisms are still not well studied and formulated. Hence, there is still no clear method to optimally arrange the fractal-tree microchannels (FTMCs) in a rectangular heat sink to achieve better thermal and hydraulic performance. Therefore, we developed a multi-objective optimization algorithm (distributed-adaptive genetic algorithm, DAGA) to optimize the different types of novel FTMCs concerning achieving an optimal COP (coefficient of performance, heat transfer/ pumping power). The developed DAGA can improve the computational efficiency and the quality of solutions by around 87.63% and 12.48% respectively in present work. Then, taking conventional rectangular parallel microchannels (RPMCs) as a reference, the COP of the optimized FTMCs in the same heat sink shows an enhancement of around 0.09 ~ 0.57. The highest COP is achieved by the three-level branching FTMC. Furthermore, the optimized results reveal that branching level, bifurcation number, and microchannel width at the first branching level are sensible, while dimension ratio factors and microchannel length at the first branching level show low sensibility to the COP of FTMCs.

Nuclear medicine has made enormous progress in the past decades. However, there are still significant inequalities in patient access among different countries, which could be mitigated by a suitable pharmaceutical regulatory framework and associated guidelines. This paper summarizes major considerations for a suitable pharmaceutical regulatory framework to facilitate patient access to radiopharmaceuticals. These include the distinct characteristics of radiopharmaceuticals advocating dedicated regulations, the impact of variable complexity of radiopharmaceutical preparation, personnel requirements, manufacturing practices and quality assurance, regulatory authorities interfaces, communication and training, as well as marketing authorization procedures to ensure availability of radiopharmaceuticals. Finally domestic and regional supply to ensure patient access via alternative regulatory pathways, including in-house production of radiopharmaceuticals, is described and an outlook on regulatory challenges faced by new developments, such as the use of alpha emitters, is provided. All these considerations are an outcome of a dedicated Technical Meeting organized by the IAEA in 2023.

Overcoming PARPi resistance is a high clinical priority. We established and characterized comparative in vitro models of acquired PARPi resistance, derived from either a BRCA1-proficient or BRCA1-deficient isogenic background by long-term exposure to olaparib. While parental cell lines already exhibited a certain level of intrinsic activity of multidrug resistance (MDR) proteins, resulting PARPi-resistant cells from both models further converted toward MDR. In both models, the PARPi-resistant phenotype was shaped by (i) cross-resistance to other PARPis (ii) impaired susceptibility toward the formation of DNA-platinum adducts upon exposure to cisplatin, which could be reverted by the drug efflux inhibitors verapamil or diphenhydramine, and (iii) reduced PARP-trapping activity. However, the signature and activity of ABC-transporter expression and the cross-resistance spectra to other chemotherapeutic drugs considerably diverged between the BRCA1-proficient vs. BRCA1-deficient models. Using dual-fluorescence co-culture experiments, we observed that PARPi-resistant cells had a competitive disadvantage over PARPi-sensitive cells in a drug-free medium. However, they rapidly gained clonal dominance under olaparib selection pressure, which could be mitigated by the MRP1 inhibitor MK-751. Conclusively, we present a well-characterized in vitro model, which could be instrumental in dissecting mechanisms of PARPi resistance from HR-proficient vs. HR-deficient background and in studying clonal dynamics of PARPi-resistant cells in response to experimental drugs, such as novel olaparib-sensitizers.

A review of single photon emitters in silicon based on ion-induced defects is provided. Fabrication methods and current state of the art are discussed.

The structural stability of DNA origami nanostructures in various chemical environments is an important factor in numerous applications, ranging from biomedicine and biophysics to analytical chemistry and materials synthesis. In this work, the stability of six different 2D and 3D DNA origami nanostructures is assessed in the presence of three different chatropic salts, i.e., guanidinium sulfate (Gdm2SO4), guanidinium chloride (GdmCl), and tetrapropylammonium chloride (TPACl), which are widely employed denaturants. Using atomic force microscopy (AFM) to quantify nanostructural integrity, Gdm2SO4 is found to be the weakest and TPACl the strongest DNA origami denaturant, respectively. Despite different mechanisms of actions of the selected salts, DNA origami stability in each environment is observed to depend on DNA origami superstructure. This is especially pronounced for 3D DNA origami nanostructures, where mechanically more flexible designs show higher stability in both GdmCl and TPACl than more rigid ones. This is particularly remarkable as this general dependence has previously been observed under Mg2+-free conditions and may provide the possibility to optimize DNA origami design toward maximum stability in diverse chemical environments. Finally, it is demonstrated that melting temperature measurements may overestimate the stability of certain DNA origami nanostructures in certain chemical environments, so that such investigations should always be complemented by microscopic assessments of nanostructure integrity.

Indistinguishable single-photon sources at telecom wavelengths are the key photonic qubits for transmitting quantum information over long distances in standard optical fibers with minimal transmission losses and high fidelity. This enables secure quantum communication over the quantum internet and, in turn, a modular approach to quantum computing. The monolithic integration of single-photon sources with reconfigurable photonic elements and single-photon detectors in a silicon chip is a key enabling step toward demonstrating scalable quantum hardware such as quantum photonic integrated circuits (QPICs). Nowadays, nearly all the necessary components for QPICs are available such as superconducting single-photon detectors, low-loss photonic waveguides, delay lines, modulators, phase shifters, and low-latency electronics. Yet, the practical implementation of scalable quantum hardware has been largely hampered by the lack of on-chip single-photon emitters in silicon that can be created at desired locations on the nanoscale.
Here, we demonstrate two complementary wafer-scale protocols for the quasi-deterministic creation of single G and W telecom-wavelength color centers in silicon with a probability exceeding 50%. Both approaches are fully compatible with current silicon technology and enable the fabrication of single telecom quantum emitters at desired nanoscale positions on a silicon chip. These results unlock a clear and easily exploitable pathway for industrial-scale photonic quantum processors with technology nodes below 100 nm.

HELPMI is a 2-year project, subsidized by the Helmholtz Metadata Collaboration, conducted by GSI, HI Jena and HZDR (lead). The aim is to start the development of a F.A.I.R. data standard for experimental data of the entire laser-plasma (LPA) community. Such standard does not yet exist. It will facilitate management and analysis of usually quite heterogeneous experimental data and logs by rich and machine-actionable metadata, allowing automated processing of broad and long data sets. To date, the LPA community is widely using openPMD, an open meta-standard, well-established for simulations. NeXus is a similarly hierarchical and extensible standard for various experimental methods of the Photon and Neutron science community. Within HELPMI, we plan to adopt NeXus for LPA experimental data and simultaneously to make openPMD and its API extensible for custom hierarchies like NeXus. Thereby we can achieve interoperability of the standards, circumventing the need for another standard. Alongside we will start developing a glossary of LPA experimental terms in order to achieve re-usability. The glossary shall be community-driven and technically open, extensible and implementation-independent.

Nanogels open up access to a wide range of applications and offer among others hopeful approaches for use in the field of biomedicine. This review provides a brief overview of current developments of nanogels in general, particularly in the fields of drug delivery, therapeutic applications, tissue engineering and sensor systems. Specifically, cyclodextrin (CD)-based nanogels are important because they have exceptional complexation properties and are highly biocompatible. Nanogels as a whole and CD-based nanogels in particular can be customized in a wide range of sizes and equipped with a desired surface charge as well as containing additional molecules inside and outside, such as dyes, solubility-mediating groups or even biological vector molecules for pharmaceutical targeting. Currently, biological investigations are mainly carried out in vitro, but more and more in vivo applications are gaining importance. Modern molecular imaging methods are increasingly being used for the latter. Due to an extremely high sensitivity and the possibility of obtaining quantitative data on pharmacokinetic and pharmacodynamic properties, nuclear methods such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) using radiolabeled compounds are particularly suitable here. The use of radiolabeled nanogels for imaging, but also for therapy, is being discussed.

Placing quantum materials into optical cavities can provide a unique platform to control
quantum cooperative properties of matter, in the regimes of both weak and strong light-matter coupling. Here we show the first experimental evidence of the reversible touchless control of a metal-to-insulator phase transition in the charge density wave material 1T-TaS2 embedded in a tunable THz optical cavity. The switch between conductive and insulating behavior, which is obtained by mechanically tuning the distance between the cavity mirrors and their alignment, is related to a significant renormalization of the sample temperature. This suggests a Purcell-like scenario in which the spectral profile of the cavity modifies the energy exchange between the material and the external electromagnetic field. Our findings uncover a new path to control the thermodynamics and macroscopic transport properties of quantum materials by engineering their electromagnetic environment.

Strong circularly polarized excitation opens up the possibility to generate and control effective magnetic fields in solid state systems, e.g., via the optical inverse Faraday effect or the phonon inverse Faraday effect. While these effects rely on material properties that can be tailored only to a limited degree, plasmonic resonances can be fully controlled by choosing proper dimensions and carrier concentrations. Plasmon resonances provide new degrees of freedom that can be used to tune or enhance the light-induced magnetic field in engineered metamaterials. Here we employ graphene disks to demonstrate light-induced transient magnetic fields from a plasmonic circular current with extremely high efficiency. The effective magnetic field at the plasmon resonance frequency of the graphene disks (3.5 THz) is evidenced by a strong (~1°) ultrafast Faraday rotation (~ 20 ps). In accordance with reference measurements and simulations, we estimated the strength of the induced magnetic field to be on the order of 0.7 T under a moderate pump fluence of about 440 nJ cm-2.

Our research aims at a better understanding of fundamental processes defining transport and accumulation of radiotoxic elements such as U, Np, Pu, Am, Cm, as well as Tc and Se. This requires knowledge of their mobility in the environment and of their (radio)ecological behavior. The results will help to develop biochemically and radiochemically founded risk assessment schemes, remediation procedures in areas affected by uranium mining, and help to assess the long-term safety of final disposal sites for nuclear waste in geologic formations.
Therefore, we apply solution- and solid-state NMR to various simple and complex systems. Occasionally, lanthanide ions, Ln(III), are used as non-radioactive, isoelectronic analogs for trivalent actinides, An(III). Radionuclide complexation by small molecules is studied for, e.g., citrate [1,2], glutathione (GSH/GSSG) [3,4], as well as 2-phosphonobutane-1,2,4,-tricarbox-ylate (PBTC) [5] and nitrilotriacetate (NTA) [6]. Selenium and (organo)borates were subject of NMR studies, too [7–9]. Comprehensive kinetic and thermodynamic studies were performed for water addition to PQQ, a redox cofactor in Ln(III)-dependent alcohol dehydrogenases [10]. Indicator molecules excreted from carrot cells or fungi upon treatment with uranium were identified also by NMR [11,12]. Furthermore, the bulk structure as well as the interaction of organics (e.g., gluconate, PBTC) and/or radionuclides with calcium (aluminate) silicate hydrate (C (A )S H) phases related to cementitious materials critical for nuclear waste disposal infrastructures were characterized by 13C, 31P, 27Al, and 29Si MAS NMR [13,14].

Literature:

[1] J. Kretzschmar et al., Chem. Commun. 2020, 56, 13133. [2] J. Kretzschmar et al., Inorg. Chem. 2021, 60, 7998. [3] J. Kretzschmar et al., Chem. Commun. 2018, 54, 8697. [4] J. Kretzschmar et al., Inorg. Chem. 2020, 59, 4244. [5] J. Kretzschmar et al., Molecules 2022, 27, 4067. [6] S. Friedrich et al., Molecules 2023, submitted. [7] J. Kretzschmar et al., Dalton Trans. 2015, 44, 10508. [8] J. Schott et al., Dalton Trans. 2014, 43, 11516. [9] J. Schott et al., Dalton Trans. 2015, 44, 11095. [10] N. Al Danaf et al., Phys. Chem. Chem. Phys., 2022, 24, 15397. [11] J. Jessat et al., J. Hazard. Mater. 2022, 439, 129520. [12] A. Wollenberg et al., J. Hazard. Mater. 2021, 411, 125068. [13] S. Dettmann et al., Front. Nucl. Eng. 2023, 2, 1124856. [14] K. Schmeide et al., in preparation.

Pulsed filtered cathodic arc deposition involves formation of energetic multiply charged metal ions, which help to form dense, adherent, and macroparticle-free thin films. Ions possess not only significant kinetic energy, but also potential energy primarily due to their charge, which for cathodic arc plasmas is usually greater than one. While the effects of kinetic ion energy on the growing film are well investigated, the effects of the ions’ potential energy are less known. In the present work, we make a step towards decoupling the contributions of kinetic and potential energies of ions on thin film formation. The potential energy is changed by enhancing the ion charge states via using an external magnetic field at the plasma source. The kinetic energy is adjusted by biasing the arc source (“plasma bias”), which allows us to approximately compensate the differences in kinetic energy while the substrate and ion energy detector remain at ground. However, application of an external magnetic field also leads to an enhancement of the ion flux and hence the desired complete decoupling of the potential and kinetic energy effects will require further steps. Charge-state-resolved energy distribution functions of ions are measured at the substrate position for different arc source configurations, and thin films are deposited using exactly those configurations. Detailed characterization of the deposited thin films is performed to reveal the correlations of changes in structure with kinetic and potential energies of multiply charged ions. It is
observed that the cathode composition (Al:V ratio) strongly affects the formation of the thermodynamically stable wurtzite or the metastable cubic phase. The external magnetic field applied at the arc source is found to greatly alter the plasma and therefore to be the primary, easily accessible
“tuning knob” to enhance film crystallinity. The effect of “atomic scale heating” provided by the ions’ kinetic and potential energies on the film crystallinity is investigated, and the possibility to deposit crystalline (V,Al)N films without substrate heating is demonstrated. This study shows an approach towards
distinguishing the contributions stemming from kinetic and potential energies of ions on the film growth, however, further research is needed to assess and distinguish the additional effect of ion flux intensity (current).

Reactor pressure vessel (RPV) steels in nuclear reactors face embrittlement due to neutron irradiation. The embrittlement is associated with an increase in the reference temperature obtained via fracture toughness testing using the Master Curve concept. However, the fracture surfaces of some highly embrittled RPV steels exhibit ductile dimples. Through this work, we show that material properties, such as yield strength as a function of temperature, play an important role in determining the net hardening of a material. Additionally, we recorded the location of fracture initiators, using scanning electron microscopy (SEM) on the fracture surfaces of tested mini-C(T) specimens from four different RPV steels, to check whether it was affected by neutron irradiation and side grooving. We detected fracture initiators associated with high fracture toughness at greater distances to the crack tip. The locations of the fracture initiators changed significantly for samples with and without side-grooves and did not change significantly with respect to the irradiation state. We found the primary causes for increased ductility of embrittled RPV steels to be lower irradiation induced hardening and a higher loss in yield strength with increasing temperatures. Caution must therefore be exercised while interpreting the embrittlement of a material using ductile fracture surfaces alone.

Warm dense matter (WDM) is now routinely created and probed in laboratories around the world, providing unprecedented insights into conditions achieved in stellar atmospheres, planetary interiors, and inertial confinement fusion experiments. However, the interpretation of these experiments is often filtered through models with systematic errors that are difficult to quantify. Due to the simultaneous presence of quantum degeneracy and thermal excitation, processes in which free electrons are de-excited into thermally unoccupied bound states transferring momentum and energy to a scattered x-ray photon become viable [1]. Here we show that such free-bound transitions are a particular feature of WDM and vanish in the limits of cold and hot temperatures. The inclusion of these processes into the analysis of recent X-ray Thomson Scattering experiments on WDM at the National Ignition Facility [2] and the Linac Coherent Light Source [3] significantly improves model fits, indicating that free-bound transitions have been observed without previously being identified. This interpretation is corroborated by agreement with a recently developed model-free thermometry technique [4,5] and presents an important step for precisely characterizing and understanding the complex WDM state of matter.

[1] M. Böhme et al, arXiv:2306.17653
[2] T. Döppner et al, Nature 618, 270-275 (2023)
[3] D. Kraus et al, PPCF 61, 014015 (2019)
[4] T. Dornheim et al, Nature Commun 13, 7911 (2022)
[5] T. Dornheim et al, POP 30, 042707 (2023)

We present an evaluation study on the characterization of bubbles rising in liquid sodium by applying two-plane ultrafast X-ray computed tomography (UFXCT). It includes a new method for determining the three-dimensional shape and velocity vector of each individual bubble. In the experimental part, argon gas was injected through a single nozzle located slightly above the bottom of a cylindrical vessel filled with liquid sodium. The gas flow rate was varied between 10 and 635 cm3/min to obtain a chain of individual bubbles. In this parameter range, collisions of bubbles, coalescence or breakup are not expected. Measurements were carried out in a wide spatial range starting near the nozzle up to a height of about 200 mm above it. It was convincingly demonstrated that two-plane UFXCT imaging, in combination with the data processing presented here, allows a reliable characterization of the size, shape and velocity of bubbles with a size of a few millimeters in a sodium column of 54 mm diameter. Observed experimental results include a reproducible fluctuation of shape, position and velocity in the lower part of the column as well as lower terminal rise velocities compared to bubble chains in water.

The study of matter at extreme densities, temperatures, and pressures has emerged as a highly active frontier at the interface of a variety of disciplines including physics, material science, and quantum chemistry. Such warm dense matter (WDM) naturally occurs in astrophysical objects like giant planet interiors and brown dwarfs. Moreover, it is of key relevance for technological applications such as inertial confinement fusion and material synthesis. A particular feature of WDM is the complex interplay of effects such as Coulomb coupling and quantum degeneracy rendering its rigorous theoretical description a formidable challenge. Here I present an overview of a number of recent developments that bridge the gap between state-of-the-art simulation methods and WDM experiments [1,2]. These new methodologies have already been successfully applied to inelastic x-ray scattering experiments at the European XFEL and the National Ignition Facility [3,4], and open up a variety of exciting possibilities for future research at HIBEF.

[1] T. Dornheim et al, Nature Commun. 13, 7911 (2022)
[2] T. Dornheim et al, Phys. Plasmas 30, 032705 (2023)
[3] T. Dornheim et al, arXiv:2305.15305 (submitted)
[4] M. Böhme et al, arXiv:2306.17653 (submitted)

We studied the high-field phase diagram of a chiral-lattice antiferromagnet Sr(TiO)Cu₄PO₄)₄ by means of ultrasound, dielectric, and magnetocaloric-effect measurements. These experimental techniques reveal two new phase transitions at high fields, which have not been resolved by previous magnetization experiments. Specifically, the c₆₆ acoustic mode shows drastic changes with hysteresis for magnetic fields applied along the c axis, indicating a strong magnetoelastic coupling. Combined with cluster mean-field theory, we discuss the origin of these phase transitions. By considering the chiral-twist effect of Cu₄O₁₂ cupola units, which is inherent to the chiral crystal structure, the phase diagram is reasonably reproduced. The agreement between experiment and theory suggests that this material is a unique quasi-two-dimensional spin system with competing exchange interactions and chirality, leading to a rich phase diagram.

Flashing flows of initially sub-cooled water in a converging–diverging nozzle is investigated numerically in the framework of the two-fluid model (TFM). The thermal non-equilibrium effect of phase change is considered by an interfacial heat transfer model, while the pressure jump across the interface is ignored. The bubble size distribution induced by nucleation, bubble growth/shrinkage, coalescence, and breakup is described based on the interfacial area transport equation (IATE) and constant bubble number density model (CBND), respectively. The results are compared with the experimental data. Satisfactory prediction of the axial pressure distribution along the nozzle as well as the flashing inception, is achieved by the TFM-IATE coupling method. It was also found that the vapor production in the diverging section was overpredicted, and the radial gas volume fraction distribution deviated from the experiment. The radial diameter profiles exhibit opposite patterns at the nozzle throat and near the outlet, and similar trends can be observed for the superheated degree. A poly-disperse method is suggested to be introduced to describe the evolution of interfacial area concentration.

The behaviour of any physical system is determined by the order parameter whose distribution is governed by the geometry of the physical space of the object, in particular its dimensionality and curvature [1]. Curvilinear magnetism is a framework, which helps understanding the impact of geometrical curvature on complex magnetic responses of curved 1D wires and 2D shells [2-4]. The lack of inversion symmetry and emergence of curvature induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI) stemming from the exchange interaction [5,6] are characteristic of curved surfaces. Recently, a non-local chiral symmetry breaking was discovered [7], which is responsible for the coexistence and coupling of multiple magnetochiral properties within the same magnetic object [8]. Regarding antiferromagnets, it is demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [9-11]. This positions curvilinear antiferromagnets as a platform for geometrically tunable antiferromagnetic spinorbitronics.

[1] P. Gentile et al., “Electronic materials with nanoscale curved geometries”. Nature Electronics (review) 5, 551 (2022).
[2] D. Makarov et al., “Curvilinear micromagnetism: from fundamentals to applications” (Springer, Zurich, 2022).
[3] D. Makarov et al., “New dimension in magnetism and superconductivity: 3D and curvilinear nanoarchitectures”. Adv. Mat. (review) 34, 2101758 (2022).
[4] D. Sheka et al., “Fundamentals of curvilinear ferromagnetism: statics and dynamics of geometrically curved wires and narrow ribbons”. Small (review) 18, 2105219 (2022).
[5] Y. Gaididei et al., “Curvature effects in thin magnetic shells”. Phys. Rev. Lett. 112, 257203 (2014).
[6] O. Volkov et al., “Experimental observation of exchange-driven chiral effects in curvilinear magnetism”. Phys. Rev. Lett. 123, 077201 (2019).
[7] D. Sheka et al., “Nonlocal chiral symmetry breaking in curvilinear magnetic shells”. Commun. Phys. 3, 128 (2020).
[8] O. Volkov et al., “Chirality coupling in topological magnetic textures with multiple magnetochiral parameters”. Nature Com. 14, 1491 (2023).
[9] O. Pylypovskyi et al., “Curvilinear one-dimensional antiferromagnets”. Nano Lett. 20, 8157 (2020).
[10] O. Pylypovskyi et al., “Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains”. Appl. Phys. Lett. 118, 182405 (2021).
[11] Y. Borysenko et al., “Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains”. Phys. Rev. B 106, 174426 (2022).

In this lecture for magnetism students, we cover different fabrication methods to produce bulk, thin film, composites, 3D magnetic functional samples.

In this lecture for magnetism students we review different magnetic materials with focus on their functionality and related application directions. Bulk, thin films, 2D materials, heterostructures, 3D magnetic architectures are addressed in the lecture.

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe_1.908Ni_0.092As₂ single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10^–4) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe_1.908Ni_0.092As₂ can be well explained by a flux-pinning-induced mechanism.

Die Reduktion klimaschädlicher Emissionen ist ein wesentliches Ziel im modernen Luftverkehr. Dafür geeignete Ansätze
stellen unter anderem emissionsoptimierte Flugprofile sowie der Einsatz von hybrid-elektrischen Antriebstechnologien
dar. Um die damit verbundenen Potentiale zügig identifizieren und quantifizieren zu können, werden performante
0D-Triebwerksmodelle benötigt, die die Leistungsrechnung thermischer und hybrid-elektrischer Flugantriebe im Auslegungspunkt
und im Off-Design abbilden.
Die vorliegende Arbeit stellt ein solches Modell für Leistungsrechnung, Emissions- und Massenabschätzung vor. Dabei
liegt ein besonderer Fokus auf einem flexiblen, modularen Aufbau, sodass das Framework um neue Architekturen
und zusätzliche (bspw. elektrische) Komponenten erweitert werden kann. Bereits hinterlegt sind etablierte ein- und
mehrwellige thermische Turbojet-, Turbofan- und Turboprop-Architekturen sowie verschiedene (hybrid-)elektrische
Konfigurationen. Gegenüber einer etablierten kommerziellen Referenz (GasTurb) ergeben sich für die Leistungsgrößen
dort verfügbarer Architekturen Abweichungen deutlich kleiner als ein Prozent, die typischerweise durch die
Genauigkeit der verfügbaren Stoffwerte limitiert werden. Das Triebwerksdesign kann in einem Auslegungspunkt
definiert und quasi-stationär im Off-Design berechnet werden, wobei die entlang einer Flugmission entstehenden
Schubanforderungen mittels der Bibliothek OpenAP vorgegeben werden können. An dieser Stelle schlägt sich die
Abschätzung des Systemgewichts, welches durch die jeweilige Architektur und ihre Komponenten erheblich beeinflusst
wird, besonders nieder. Dies wird bspw. hinsichtlich des Treibstoffverbrauchs anhand eines ausgewählter Missionsprofils
demonstriert. Für die Massen- und Emissionsabschätzung wird auf eine Datenbank bestehender Maschinen
zurückgegriffen.
Die aktuelle und zukünftige Entwicklung des Modells konzentriert sich auf eine weiter verbesserte Massenabschätzung,
alternative Kraftstoffe und weitere Triebwerksarchitekturen, insbesondere mit Wärmeübertragern, die dank des
modularen Aufbaus leicht eingebunden werden können. Damit ermöglicht dieses Leistungsrechnungsprogramm eine
noch schnellere und umfangreichere Vorhersage von thermodynamischen Größen entlang des Gaspfades, Effizienz,
Emissionen und Massen für die erfolgreiche Evaluation neuer Triebwerksdesigns und Missionsprofile.

Droplet-based microfluidics that emerged a decade ago has offered a new route to boost the efficiency of biochemical methods in terms of detection time and sensitivity [Kaminski et al., Chem. Soc. Rev. 46, 2017]. Droplet-based fluidic technology saves materials consumption and reduces experimental wastes, allowing for real-time and individual tracking of each reactor, and has found numerous applications in biology and biotechnology [Baraban et al., Lab. Chip, 11, 2011]. In our lab, we developed a droplet-based microfluidic system to detect the bioreaction (e.g., bacterial growth, antibiotic effect, enzyme reaction dynamic, and so on) in high throughput and sensitivity by detecting fluorescence signals. The system achieves monitoring the bioreaction in the hundred to thousand droplets with the size of 200 nL with multi-channel automatically. Depending on the different purposes, this system can be adjusted to monitor the same batch of analytes over time in the long term (days), or continuously real-time detect analytes level change, as well as to switch between various optical settings.
For example, we used the millifluidic droplets reactor system to study the bacterial coexistence by monitoring two Escherichia coli strains' growth simultaneously in real time [Zhao et al., Lab. Chip, 21, 2021]. Our system offers an environment with high statistical output, unaffected bacteria growth, and long-time measurements in a well-mixed liquid inhabit. By reading fluorescence in two parallel detector channels, we obtained and analyzed the monoculture and co-culture of these two strains E. coli BFP and E. coli YFP and explained the interaction and relationship between them. In another work, we investigated the antibiotic effect on bacterial coexistence. Our automatic nanoliter droplet analyzer is used to study the interactions of the sensitive and resistant strains of E. coli in the presence of antibiotics and to define the criteria leading to the emergence of cross-protection phenomena.
Moreover, due to the quick response and high sensitivity properties, we miniaturized the system to a bedside portable size and introduced it to the clinical field of real-time sensing drain α-amylase activity for postoperative monitoring of patients undergoing pancreatic surgery. Based on the reaction of the starch-FL reagent with amylase to produce a fluorescence intensity that correlates with the concentration of amylase, thus enabling the detection of the patient's amylase level. In this work, our strategy significantly improves the determination time (3 min) and detection limit (7 nmol/s·L) and reduces material requirement (10 μL) and wastes.
In the future, we expect to apply our portable device in more clinical scenarios, e.g., lactate and lipase level monitoring, and septicemia determination, in which case bacteria poisons the blood, and needs urgent and accurate low-concentration detection. Not limited to aqueous phase droplets, our research group also focused on solid and semi-solid environments, such as incubating bacteria or cancer cells in gel beads or capsules. For instance, we encapsulated two bacterial strains in agarose gel beads to study the effect of space on bacterial coexistence [Nguyen Le et al., Micromachines, 14, 2023]. We also cultured cancer cells in capsules and adjusted the core-shell ratio to structure cell growth conditions [Peng et al., Biotechnology Journal, 2023].

The accurate determination of light absorption in the material is necessary to understand the photocatalytic mechanism. Here, we present the systematic study of light absorption in the prototypical Van derWaals (vdW) heterostructure PtS2-SnS2 by including the electron-hole interaction in the computational calculation by the GW Bethe Salpeter Equation (GW-BSE) approach. The GGA-PBE level bandgap of the PtS2 -SnS2 vdW heterostructure is calculated to be 1.09 eV which is less than that of monolayers of PtS2 and SnS2. Later, GW-BSE absorption spectra pointed out the bound excitonic peaks of PtS2-SnS2 vdW heterostructure which have significant impact on the light absorption property of the material. The first excitonic peak of this vdW heterostructure obtained at the 2.17 eV which is in the low energy range compared to monolayers of PtS2 and SnS2. This low energy shift of the first excitonic peak will be favourable for better light absorption as well as boosted photoconversion efficiency of the PtS2-SnS2 vdW heterostructure.

The newly discovered monolayer selenium from group VI elements gains prominence due to its potential application in diverse fields including optoelectronics. In this work we have performed a systematic first principles study on the structural, electronic, linear and nonlinear optical characteristics of selenium Van der Waals (vdW) heterostructure with noble metal chalcogenide PtS2. The GW-Bethe-Salpeter Equation (GW-BSE) approach was used to accurately treat the quasiparticle and excitonic spectra. The optimized heterostructure shows the indirect band gap of 0.82 eV at GGA-PBE level. The newly designed interface shows type II band alignment. GW-BSE absorption spectra show a bound excitonic peak at 1.40 eV as compared with 1.28 eV in monolayer Se. The exciton binding energy of the Se-PtS2 vdW interface is 0.35 eV compared with the 0.45 eV for monolayer Se. The strong excitonic visible light absorption together with the type II band alignment makes the Se-PtS2 vdW heterostucture suitable candidate for the photovoltaic and photocatalytic applications.

Electron correlation microscopy experiments were conducted on amorphous germanium (a-Ge) and amorphous silicon (a-Si) with the goal to study self-diffusion. For this purpose, a series of tilted dark-field images were acquired during in situ heating of the samples in a transmission electron microscope. These experiments show that the measurements are greatly affected by artefacts. Contamination, crystallization, electron beam-induced sputtering, and macroscopic bending of the samples pose major obstacles to the measurements. Other, more subtle experimental artefacts could occur in addition to these which makes interpretations regarding the structural dynamics nearly impossible. The data were nonetheless evaluated to see if some useful information could be extracted. One such result is that the distribution of the characteristic times τ(KWW⁠), which were obtained from stretched exponential fits to the intensity autocorrelation data, is spatially heterogeneous. This spatial heterogeneity is assumed to be caused by a potential nonergodicity of the materials, the artefacts or an inhomogeneous amorphous structure. Further data processing shows that the characteristic times τ(KWW) are moreover temperature independent, especially for the a-Ge data. It is concluded that the structural rearrangements over time are primarily electron beam-driven and that diffusive dynamics are too slow to be measured at the chosen, experimentally accessible annealing temperatures.

The electronic, thermodynamic, and optical properties of a new type of twodimensional Janus layer (JL) consisting exclusively of chalcogens are investigated using first principles calculations. The permutations on atomic sites provide increased stability due to the multi-valency of chalcogens, and a heavier central atom further stabilizes the layer due to the increased coordination number. The investigated JLs are indirect bandgap materials with a bandgap larger than 1.23 eV, making them suitable for photocatalytic activity. Different feasible chemical potentials are analyzed, and chalcogens’ poor limits are proposed to fabricate the JLs. Based on the comparison of the formation energy, the energetic profile of the JLs is identified as Ef(TeSeS) < Ef(SSeTe) < Ef(SeSTe), irrespective of the chemical potentials of chalcogen. Hence, TeSeS is more stable than the JL arrangements SSeTe and SeSTe. The flat bands around the Fermi energy level and the reduction in path length between the maximum of conduction and minimum of valence bands explain the magnitude of multiple peaks observed in the optical spectra of the JLs. These absorptions turn the studied JLs into potential candidates for water splitting. The optimized bandgap reveals that the band edges efficiently straddle the water redox potentials at different pH levels. In addition, the positive vibrational frequencies depict the stability of these layers. Because of the minimal formation energy requirement, higher density of states around the Fermi level, as well as enhanced optical absorption compared to other JL, TeSeS JLs may lead to enhanced performance in photovoltaic and photocatalytic applications. These results add new members to the JL family of pure chalcogens and pave the way toward novel materials for respective applications.

We use a pure spin current originating from the spin Hall effect to generate a spin-orbit torque strongly reducing the effective damping in an adjacent ferromagnet. Because of additional microwave excitation, large spin-wave amplitudes are achieved exceeding the threshold for four-magnon scattering, thus resulting in additional spin-wave signals at discrete frequencies. Two or more modes are generated below and above the directly pumped mode with equal frequency spacing. It is shown how this nonlinear process can be controlled in magnonic waveguides by the applied dc current and the microwave pumping power. The sudden onset of the nonlinear effect after exceeding the thresholds can be interpreted as a spiking phenomenon, which makes the effect potentially interesting for neuromorphic computing applications. Moreover, we investigated this effect under microwave frequency and external field variation. The appearance of the additional modes was investigated in the time domain, revealing a time delay between the directly excited and the simultaneously generated nonlinear modes. Furthermore, spatially resolved measurements show different spatial decay lengths of the directly pumped mode and nonlinear modes.

This study aims at improving the empirical correlation for estimating the yield strength from small punch tests. The currently used procedure in the European standard EN 10371 to determine the elastic-plastic transition force – based on bi-linear fitting – involves a dependency not only on the onset of plastic flow but also on the work hardening of the material. Consequently, the yield strength correlation factor is not universal but depends on the material properties and on the ge-ometry of the small punch set-up – leading to a significant uncertainty in the yield strength estima-tion. In this study, an alternative definition of the elastic-plastic transition force is proposed, which significantly less depends on the work hardening of the material and on the small punch geome-try. The approach is based on extensive elastic-plastic finite element simulations with generic ma-terial properties, including a systematic variation of the yield strength, ultimate tensile strength, and uniform elongation. The new definition of the transition force is based on the deviation of the force-deflection curve from the analytical elastic slope derived by Reissner's plate theory. A signifi-cant reduction of the uncertainty of the yield strength estimation is demonstrated.

Hydrogen isotope separation is of prime significance in various scientific and industrial applications. Nevertheless, the existing technologies are often expensive and energy demanding. Two-dimensional carbon materials are regarded as promising candidates for cost-effective separation of different hydrogen isotopes. Herein, based on theoretical calculations, we have systematically investigated proton penetration mechanism and the associated isotope separation behavior through two-dimensional biphenylene, a novel graphene allotrope. The unique non-uniform rings with different sizes in biphenylene layer resemble the topological defects of graphene, serving as proton transmission channels. We found that proton can readily pass through biphenylene with low energy barrier in some specific patterns. Furthermore, large kinetic isotope effect ratios for proton-deuteron (13.58) and proton-triton (53.10) were observed in aqueous environment. We thus conclude that biphenylene would be a potential carbon material used for hydrogen isotope separation. This subtle exploitation of the natural structural specificity of biphenylene casts new insight into the search of materials for hydrogen isotope separation.

Cone-beam CTs are a promising solution for fast imaging required by Online Adaptive Proton Therapy. Verifying adapted treatment plans with prompt-gamma-imaging (PGI) requires a reference simulation on the respective planning image. Cone-beam CTs and conventional fan-beam CTs were acquired for a homogeneous PMMA cylinder and an antropomorphic head phantom. Two RayStation algorithms were used to create a corrected cone-beam CT and a virtual CT for each phantom. PGI simulations were performed on all datasets and compared to a corresponding dose evaluation. CBCT data was shown to be suitable for PGI reference simulations if range prediction is correct, which is a requirement for plan adaptation. Uncertainty in material assignment due to noise in CBCT does not worsen PGI emission signal.

This review addresses the use of X-ray and neutron scattering and X-ray absorption to describe how inorganic nano-structured materials assemble, evolve, and function in solution. We first provide an overview of techniques and instrumentation (both large user facilities and benchtop). We review recent studies of soluble inorganic nanostructure assembly, covering the disciplines of materials synthesis, processes in nature, nuclear materials, and the widely applicable fundamental processes of hydrophobic interactions and ion-pairing. Reviewed studies cover size regimes and length scales ranging from sub-angstrom (coordination chemistry and ion-pairing) to several nanometers (molecular clusters; i.e. polyoxometalates, polyoxocations and metal-organic polyhedra), to meso-scale (supramolecular assembly processes). Reviewed studies predominantly exploit 1) SAXS/SWAXS/SANS (small and wide angle X-ray or neutron scattering), 2) PDF (pair distribution function analysis of X-ray total scattering), and 3) XANES and EXAFS (respectively X-ray absorption near edge structure and extended X-ray absorption fine structure). While the scattering techniques provide structural information, X-ray absorption yields oxidation state, in addition to local coordination. Our goal for this review is to provide information and inspiration for the inorganic/materials science communities that may benefit from elucidating the role of solution speciation in natural and synthetic processes.

Color centers in silicon carbide has been widely studied in view of the promising near-infrared emission near the low-loss telecom wavelengths as well as the maturity of semiconductor technology of silicon carbide material. Recently, there is an urgent need to generate color centers in predetermined location so as to integrate with photonic cavities of waveguides. In this paper, we report an experimentally demonstration of the generation of VSi, CSiVC, and NCVSi color centers in 4H-SiC using helium ion microscope in 5×5 µm areas with subsequent annealing treatment. Combined with transmission electron microscopy (TEM), photoluminescence (PL) and cathodoluminescence (CL) spectroscopy and Raman stress analysis, the evolution and distribution of color centers were thoroughly investigated. Cross-sectional TEM revealed the presence of helium bubbles in center of the implanted region with high doses which account for the observed quench of PL emission in center of the implanted regions in both PL and CL measurements. PL spectra from the virgin, implanted and annealed samples proved the appearance of VSi after implantation and the transformation from VSi to CSiVC and NCVSi centers after annealing at 1000 ℃. Moreover, as the increase of the implantation dose, the area of NCVSi centers increases whereas that of CSiVC decreases, which implied a competitive relationship between the formation of CSiVC and NCVSi defects. The comparison between stress distribution and CSiVC defect distribution illustrated that CSiVC centers predominantly distributed around the surface rupture region after thermal annealing where significant stress repair occurred. The results suggest that focused helium ion implantation holds promise for the precise coupling of VSi, CSiVC and NCVSi centers in predefined location in integrated photonics applications.

In the presence of the gravitational field, the energy density of matter no longer coincides with its mass density. A discrepancy exists, of course, also between the associated power spectra. Within the ΛCDM model, we derive a formula that relates the power spectrum of the energy density to that of the mass density and test it with the help of N-body simulations run in comoving boxes of 2.816 Gpc/h. The results confirm the validity of the derived formula and simultaneously show that the power spectra diverge significantly from one another at large cosmological scales.

ThTi2O6 derived compounds with the brannerite structure were designed, synthesised, and characterised with the aim of stabilising incorporation of U5+ or U6+, at dilute concentration. Appropriate charge compensation was targeted by co-substitution of Gd3+, Ca2+, Al3+, or Cr3+, on the Th or Ti site. U L3 edge X-ray Absorption Near Edge Spectroscopy (XANES) and High Energy Resolution Fluorescence Detected U M4 edge XANES evidenced U5+ as the major oxidation state in all compounds, with a minor fraction of U6+ (2–13%). The balance of X-ray and Raman spectroscopy data support uranate, rather than uranyl, as the dominant U6+ speciation in the reported brannerites. It is considered that the U6+ concentration was limited by unfavourable electrostatic repulsion arising from substitution in the octahedral Th or Ti sites, which share two or three edges, respectively, with neighbouring polyhedra in the brannerite structure.

Technetium-99 (⁹⁹Tc) is a radioactive isotope with a long half-live (211,000 a). It is produced in nuclear power plants and nuclear weapon detonation since it is a fission product of U-235 and Pu-239. In addition, 99Tc forms after gamma ray emission of metastable technetium-99 (99mTc), which is the most used isotope for cancer diagnosis at hospitals [1]. The emission of ⁹⁹Tc in the environment is hazardous for living organisms and depends on its chemical speci-ation, being especially decisive the oxidation state. Thus, several works focused on the speciation (e.g., [2–4]) and immobilization of Tc (e.g., [5,6]) based on redox changes.
The nuclear properties of Tc99 make it suitable to study Tc molecular structures by NMR [7,8] and, depending on the oxidation state and thus electron configuration, also by EPR [9] spec-troscopies. Despite the power of both these methods, they have been rarely used for envi-ronmental studies.
In this work we reduced KTcO₄ electrochemically in carbonate solutions in dependence on pH (8.2–10.0), Tc concentration (0.5–9.5 mM), carbonate concentration (5–1000 mM), and the applied potential. Tc(VII) reduction was monitored in the UV-vis range in situ using a spec-tro-electrochemical cell. At -0.85 V a pink solution (λmax 512 nm) was obtained, corresponding to a Tc(IV) carbonate species [2], whereas reduction at -0.95 V yields a bluish green solution (λmax 630 nm), associated with a Tc(III) carbonate complex [2]. The obtained solutions were then investigated by ⁹⁹Tc NMR. The −0.85 V solution reveals a resonance at ~1600 ppm, indicative of a carbonate species of Tc(V) since the chemical shift range is characteristic for Tc in +V oxidation state [7]. The other specimen yielded at −0.95 V, in addition to the former Tc(V) signal at about 1600 ppm, gives rise to one additional signal at ~152 ppm, which is in the chemical shift range expected for Tc(III) [7].
These are unprecedented NMR data on aqueous Tc carbonate species, which advance the mechanistic understanding of Tc redox behavior and help to improve safety and risk analyses for nuclear waste management.
Literature:
[1] A.H. Meena et al., Env. Chem Lett. 2017, 15, 241.
[2] J. Paquette et al., Can. J. Chem. 1985, 63, 2369.
[3] M. Chotkowski et al., J. Electroanal. Chem. 2018, 814, 83.
[4] D.M. Rodríguez et al, Inorg. Chem. 2022, 61, 10159.
[5] N. Mayordomo et al., Chem. Eng. J. 2021, 408, 127265.
[6] C.I. Pearce et al., Sci. Total Environ. 2020, 716, 132849.
[7] V.A. Mikhalev, Radiochemistry 2005, 47, 319.
[8] G.B. Hall et al., Inorg. Chem. 2016, 55, 8341.
[9] U. Abram et al., Radiochim. Acta. 1993, 63, 139.

The migration behaviour of different grain boundaries with misorientations close to the Σ3 CSL orientation relationship in
high purity Al bicrystals under the capillary driving force and applied mechanical stress was investigated. The experiments
were performed by an in-situ technique to observe and measure the boundary migration with a scanning electron
microscope. The ability of the nearly Σ3 60°〈111〉 incoherent {110} and {112} boundaries to move under capillary driving
force was found to depend critically on the initial boundary inclination. While boundaries with inclinations near {112} can
easily assume a curved shape and migrate, boundaries with an initial {110} plane remain stationary or form non-mobile
facets. This is attributed to the essential anisotropy of the inclination dependence of the energy γ(ψ) of 60°〈111〉 tilt
boundaries with differently high torque dγ/dψ around {112} and {110} inclinations, as revealed by atomistic simulations of the
respective boundaries. The Σ3 70.5°〈110〉 tilt boundary with the geometry corresponding to the coherent {111} twin
boundary, was found to be immobile under both driving forces applied. The 59.2° 〈111〉 tilt grain boundary with geometry
near the Σ3 {110} incoherent twin boundary was found to be quite mobile under applied shear stress. The measured
migration activation enthalpy H = 0.45 eV for this boundary is the lowest among the values obtained in previous experiments
for any other stress driven grain boundary in Al bicrystals of the same purity. Moreover, this boundary migrated with a zero
coupling factor, i.e. without producing any measurable shear parallel to the boundary plane.

High Entropy Alloys (HEAs) are prospective materials for nuclear fusion reactors and were irradiated in this study at a broad range of energetic ion fluences. Different ion masses (Cu and Au ions) and energies (3 and 5 MeV) were selected to investigate dpa (displacement per atom) development, radiation defect accumulation based on prevailing collision processes (Au ions) and ionization processes (Cu ions) in various HEAs. The studied HEAs differ in terms of elemental composition, internal morphology (grain structure) and other modifiers. Dpa values of 1 to ~66 were achieved at Cu and Au ion fluences from 4e14 to 1.3e16 ions.cm-2 at room temperature, which generated varying levels of lattice damage. Theoretical simulations were performed to estimate the energy stopping and dpa depth distribution using SRIM code and compared with Au-concentration depth profiles determined by Rutherford backscattering
spectrometry for Au-ions with 3MeV ion energy. The prevailing energy losses of ions via ionization processes for Cu-5MeV ions were found to increase the damage through lattice strain and probable lattice distortion, although the main defect introduction is expected to occur via collisions during nuclear stopping. Structural modification and defect accumulation were investigated by positron annihilation spectroscopy (PAS), which revealed a broader damaged layer with defects, where HEA-Nb (NbCrFeMnNi) exhibited the least damage accumulation from chosen alloys with no strong relation to the Au-5MeV ion implantation fluence, whereas strong defect accumulation was recorded in the Au-ion implanted Eurofer97 used for comparison and HEA-Co (CoCrFeMnNi). PAS analysis also allowed defect sizes to be determined as an additional structural characteristic. The observed trends were also confirmed by thermal property analysis, with a worsening of thermal effusivity recorded after the irradiation in HEA-Co and Eurofer97. The worsening of the thermal properties was confirmed by the layer thickness, where the layer identified by PAS was found to be broader than the SRIM theoretical predictions. Nanoindentation measurements confirmed less pronounced radiation hardening of HEA-Nb relative to that observed in HEA-Co and Eurofer97. Transmission Electron Microscopy (TEM) analysis revealed layer thicknesses in reasonable agreement with the dpa depth profiles. The thermal effusivity decreased in the surfaceirradiated layer in all investigated samples, the least influenced material was HEA-Nb.

As well known, the quality of the photocathodes is critical for the stability and reliability of photo-injector operation. Especially for the superconducting rf guns, the photocathode is one of the most important parts. In last years, thanks to the developed photocathode technology, several SRF guns were successfully operated or tested for the beam generation at kHz-MHz repetition rate. In this review, the achievements as well as open questions for the cathode requirements of the reliable SRF gun operation will be reviewed, and the possible improvement from photocathodes point of view for the future application will be discussed.

The insulator–metal transition in liquid hydrogen is an important phenomenon to understand the interiors of gas giants, such as Jupiter and Saturn, as well as the physical and chemical behavior of materials at high pressures and temperatures. Here, the path toward an experimental approach is detailed based on spectrally resolved x-ray scattering, tailored to observe and characterize hydrogen metallization in dynamically compressed hydrocarbons in the regime of carbon–hydrogen phase separation. With the help of time-dependent density functional theory calculations and scattering spectra from undriven carbon samples collected at the European x-ray Free-Electron Laser Facility (EuXFEL), we demonstrate sufficient data quality for observing C–H demixing and investigating the presence of liquid metallic hydrogen in future experiments using the reprated drive laser systems at EuXFEL.

Magnetite is a common mixed Fe(II,III) iron oxide in mineral deposits and the product of (anaerobic) iron corrosion. In various Earth systems, magnetite surfaces
participate in surface mediated redox reactions. The reactivity and redox properties of the magnetite surface depend on the surface speciation, which varies with the environmental conditions. In this study, Kohn-Sham density functional theory (DFT+U method) was used to examine the stability and speciation of the magnetite crystal face
{111} in a wide range of pH and Eh conditions. The simulations reveal that oxidation state and speciation of the surface depend strongly on imposed redox conditions and,
in general, differ from those of the bulk state. Corresponding predominance phase diagrams for the surface speciation and structure were calculated from first principles.
1The obtained knowledge of surface structure and oxidation state of iron is essential for modeling retention of redox-sensitive nuclides. Further, classical molecular dynamics
(MD) simulations were conducted investigating the mobility of water near the magnetite surface.

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a
history of how the standard has developed and grown over time. We outline the principles behind the project, and the mechanisms by which it has been extended. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS.

Quasi-2D (q2D) conjugated polymers (CPs) are polymers that consist of linear CP chains assembled through non-covalent interactions to form a layered structure. In this work, the synthesis of a novel crystalline q2D polypyrrole (q2DPPy) film at the air/H2SO4 (95%) interface is reported. The unique interfacial environment facilitates chain extension, prevents disorder, and results in a crystalline, layered assembly of protonated quinoidal chains with a fully extended conformation in its crystalline domains. This unique structure features highly delocalized π-electron systems within the extended chains, which is responsible for the low effective mass and narrow electronic bandgap. Thus, the temperature-dependent charge-transport properties of q2DPPy are investigated using the van der Pauw (vdP) method and terahertz time-domain spectroscopy (THz-TDS). The vdP method reveals that the q2DPPy film exhibits a semiconducting behavior with a thermally activated hopping mechanism in long-range transport between the electrodes. Conversely, THz-TDS reveals a band-like transport, indicating intrinsic charge transport up to a record short-range high THz mobility of ≈107.1 cm2*V^{−1}*s^{−1}.

Die EU ist bei Rohstoffen für Energiewende und Digitalisierung vom Ausland abhängig. Eine EU-Rohstoffagentur soll das ändern, fordern Jakob Kullik und Jens Gutzmer.

In this work, the range of alumina (Al₂O₃) and yttrium aluminum garnet (YAG) aerogels was extended by doping them with lanthanide ions. The aerogels were synthesized by using a universal, epoxide-assisted sol−gel method. They were thermally treated to induce structural changes, which were characterized in more detail by using X-ray diffraction and electron microscopy. The alumina samples showed topotactic phase transformations from boehmite, via γ-alumina to a mixed alumina phase, while the YAG started as an amorphous mixed oxide phase, which crystallized at 1000 °C into pure crystalline YAG. In order to expand the functionalities of the aerogels, they were doped with the rare-earth ions Eu³⁺ and Tb³⁺ (3 mol %). The red or green photoluminescence could be observed only starting from a temperature treatment of 550 °C, which can be related to the defect reduction and crystallinity increase due to phase transformations and sintering processes occurring. For the first time, the photoluminescence quantum yields of luminescent aerogels could be determined. The highest quantum yield of 25.5 ± 1.1 % was achieved for the Al₂O₃-Tb-1000 sample.

Die Lange Nacht der Wissenschaft und Wirtschaft ist seit 2007 eine Institution in Freiberg und begeistert alle zwei Jahre Groß und Klein bei spannenden Experimenten, Vorträgen und Führungen. Das Virus ließ die Neugierigen nun noch ein Jahr länger warten, aber am 18. Juni war es endlich so weit. Über 1.000 Besucher zog es ans Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF), um hautnah zu erleben, womit sich die Forschenden an einem Institut des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) so beschäftigen. Zahlreiche Experimente, Mitmach-Aktionen und Führungen begeisterten die Wissenschaftsinteressierten trotz der sommerlich heißen Temperaturen.

From microplastics to pollen grains resuspending into the atmosphere, the resuspension of microparticles by a turbulent gas flow occurs in many natural, environmental and industrial systems. A subtle interplay between drag, lift and adhesion forces occur during the particle detachment. In this lecture, the role of turbulence and wall roughness on particle deposition and resuspension will be explained. I will also showcase how can one measure aerosol deposition and resuspension in opaque and complex geometries.