Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Porous glasses produced through melt-quenching of some selective metal organic frameworks like Zeolitic Imidazolate Framework-62 (ZIF-62) and ZIF-4 belong to the advanced functional materials because of their inherent porosity, ease of processing, high gas adsorption capacity and gas separation selectivity. We have delineated thermal induced modifications in the porosity features (pore size, size-distribution and pore density) of crystalline ZIF-62 from room temperature (RT) to its melt-state (> melting point, Tm) followed by its quenching, back to RT, carrying out the depth sensitive positron annihilation lifetime spectroscopy (PALS) measurements in-situ at varying temperatures (RT-Tm). On heating under vacuum, the pores’ size as well as size-distribution of crystalline ZIF-62 increases up to ~ 473 K as a consequence of removal of entrapped solvent molecules and nonuniform thermal expansion. At higher temperatures (~ 473 - 573 K), a reduction in pores’ size and size-distribution is observed due to the loss of long range ordering and volume collapse. On melting, ZIF-62 turns into a porous liquid having ~ 1.4 times larger pores compared to its crystalline form. The quenching of this porous melt is fully irreversible, and results in the formation of a porous glass having the pores larger than its crystalline counterpart. The in-situ PALS investigation provides the first experimental evidence of inherent porosity in ZIF-62 melt existing at high temperature that has been predicted before through molecular dynamics simulation of the ZIFs-based melts.

We analyze radiation signatures from PIConGPU simulations of magnetic
reconnection. Radiation emission is calculated individually for each
particle via the Lienard-Wiechert potential. Our setup follows the
GEM-Challenge paper by Pritchett et al. (2001), ensuring well-understood
dynamics.
The observed radiation is linked to the physical processes observed. We find
characteristic radiation features for the dynamics of magnetic reconnection.
Additionally, we develop an analytic model explaining parts of the observed
radiation signal and potentially facilitating derivation of key physical
quantities from the observations, such as the power law shape of the energy
spectrum of electrons.

The first Sino-German workshop on "Deep-sea mining of massive sulfides: balancing impacts
on biodiversity and ecosystem, technological challenges and law of the sea" took place from
September 17 to September 23, 2023 in Changsha, Hunan Province, China. Four themes were
covered by 20 impulse talks, (1) seabed resources and mineralization systems, marine geology
and geochemistry, (2) microbiology and marine ecology, (3) deep-sea mining technology,
mineral processing and extractive metallurgy, and (4) law of the sea and international law
applicable to the marine environment in Areas Beyond National Jurisdiction, respectively.
In round table discussions, the interdisciplinary understanding deepened regarding (i) the
distribution of submarine massive sulfides (SMS), their formation mechanisms and the
abundance of SMS resources, (ii) the biodiversity linked to SMS and hydrothermal vents and
the environmental protection requirements, (iii) the challenges of mining technology and
processing of SMS, as well as (iv) the legal framework, the regulatory challenges, the
international environmental liability regime and due diligence obligations for commercial
seabed mining.
The participants covered all four themes and are affiliated with various universities, research
institutions, and governmental geoscientific authorities from China (seven) and Germany (six).
During the workshop, a number of recommendations to ISA were defined regarding
environmental, methodological, technical, and legal issues.

Siderophores are a diverse group of small of iron-chelating compounds which are secreted by a plethora of bacteria and fungi. In nature, their purpose is the sequestration of iron. However, due to their chemical characteristrics they are able to bind various other metals as well, making them promising compounds for the utilization in future green recycling technologies.
This work aims to find siderophores, that selectively complex the critical elements indium and germanium. As there are more than 500 different siderophores reported to this day, exhaustive experimental evaluation is highly impractical, though. Therefore, density functional theory (DFT) was utilized to model the complexation reactions and as a result estimate the affinities of the respective siderophores towards the metals of interest. With this in silico approach, siderophores that exhibited favourable binding energies were found and evaluated experimentally in order to verify the results obtained by theoretical means.
Proofing the suitability of siderophores for the selective recovery of indium and germanium from low-concentrated sources would pose as a first step in the creation of future applications of the compounds in a variety of bio-based recycling technologies, as they could aid to secure the supply of a multitude of strategic metals.

Siderophores, a group of small, yet diverse biomolecules secreted by a variety of microorganisms, are a promising compound group for the selective recovery of metals. Although their primary role is in the sequestration of iron, their chemical nature allows for the chelation of other metals. To this date, more than 500 structurally different siderophores have been identified. Based on this diversity, siderophores typically exhibit varying affinities for target metals.

Germanium represents a critical element used in various high-tech applications, such as thin films, fiber optics, or optical lenses. The wastewaters generated in the production process of germanium-containing technologies often still contain small amounts of the metal, which due to low concentrations present typically cannot be reclaimed utilizing conventional recycling technologies. The application of siderophores in a bio-based recycling approach might pose a viable solution to this challenge.

This work applied density functional theory to screen the compound group of siderophores for biomolecules exhibiting high selectivity towards germanium. Applying this approach, agrobactin, a catecholate-type siderophore, has been identified as a promising complexing agent for the selective recovery of germanium. The production of the siderophore by A. radiobacter B6 has been optimized, followed by solid phase extraction and purification of the biomolecule. The selectivity of agrobactin towards Ge was tested utilizing HPLC. Subsequently, the selective extraction of the metal from a complex solution was attempted.

Showing the suitability of agrobactin for the selective recovery of germanium opens the way to the application of siderophores for the selective recycling of a wide array of further critical metals, thus aiding in securing their future supply.

In KONA 2022, the fundamentals of two- and multidimensional particle size distributions were introduced. The next question in the field of two- and multidimensional distributions addresses their application to describe a particle process, e.g., agglomeration or separation. A multidimensional separation can be seen as retrieving only particles with a specific set of properties from a multidimensionally distributed system, e.g., retrieving only small particles (below a certain threshold in size) with a compact spherical shape (above a certain threshold in sphericity). The multidimensional separation allows the generation of functional particle systems with specific properties, e.g., semiconducting, optical, or electronic properties, which are required for high-technology applications. Starting from so-called particle-discrete information, i.e., an information vector for each particle containing its compositional, geometrical, and physical properties, it is possible to describe a multidimensional separation in full detail based on various properties. Each particle can be evaluated according to different separation properties, e.g., size, shape, and material composition. With this database, it is possible to define and work with separation functions to describe the multidimensional separation and quantify the separation results. For example, in the two-dimensional case, the median cut size becomes a median cut line, where the probability for a particle to belong to the concentrate is 0.5. Some case studies and examples show different approaches and possibilities to achieve a multidimensional separation in one or several connected process steps.

Understanding processes regulating thioarsenate (HxAsSnO4−n3−x; n = 1 – 3; x = 1 – 3) mobility is essential to predicting the fate of arsenic (As) in aquatic environments under anoxic conditions. Under such conditions, natural organic matter (NOM) is known to effectively sorb arsenite and arsenate due to metal cation-bridged ternary complexation with the NOM. However, the extent and mechanism of thioarsenate sorption onto NOM via similar complexation has not been investigated. By equilibrating monothioarsenate (representative of thioarsenate) with a peat (model NOM) with different Fe(III) loadings, this study showed that NOM can sorb monothioarsenate considerably via Fe(III)-bridging. Iron and As K-edge XAS analysis of the monothioarsenate-treated Fe-loaded peats revealed that monothioarsenate forms bidentate mononuclear edge-shared (1E) (RAs···Fe: 2.89 ± 0.02 Å) and bidentate binuclear corner-shared (2C) (RAs···Fe: 3.32 Å) complexes with organically bound Fe(O,OH)6 octahedra, in addition to direct covalent bonds with oxygen-containing functional groups (e.g., –COOH and –OH) (RAs···C: 2.74 ± 0.02 Å), upon equilibration with the Fe(III)-loaded peat. However, the extent of monothioarsenate sorption was considerably less than that of its precursor As species, arsenite, due to higher electrostatic repulsion between the negatively charged monothioarsenate and peat. This study implies that thioarsenate formation under sulfidic conditions would increase As mobility by decreasing its sorption onto the NOM.

Magnetite nanoparticles (MNPs) play an important role in geological and environmental systems because of their redox reactivity and their ability to sequester a wide
range of metals and metalloids. X-ray absorption spectroscopy conducted at metal
and metalloid edges has suggested that the magnetite 111 faces of octahedrally-shaped
nanoparticles play a dominant role in the redox and sorption processes of these elements.
However, studies directly probing the magnetite surfaces - especially in their fully solvated state - are scarce. Therefore, we investigate here the speciation and stability over
a wide Eh/pH range of octahedrally shaped MNPs of 2 nm size by means of KohnSham Density Functional Theory with Hubbard correction (DFT+U). By altering the
protonation state of the crystals, a redox-sensitive response of the octahedrally coordinated Fe could be achieved. Further, the preferential H distribution could be identified
highlighting the difference between edges, vertices and facets of the nanocrystals. Subsequently, the interactions of the MNPs with a solvent of pure water or 0.5 M NaCl
solution were studied by classical molecular dynamics (MD) simulations. Finally, a
comparison of the corresponding macroscopic magnetite (111) surface with the investigated MNPs was conducted.

Understanding laser-solid interactions is important for the development of laser-driven particle and photon sources, e.g., tumor therapy, astrophysics, and fusion. Currently, these interactions can only be modeled by simulations that need to be verified experimentally. Consequently, pump-probe experiments were conducted to examine the laser-plasma interaction that occurs when a high intensity laser hits a solid target. Since we aim for a femtosecond temporal and nanometer spatial resolution at European XFEL, we employ Small-Angle X-ray Scattering (SAXS) and Phase Contrast Imaging (PCI) that can each be approximated by an analytical propagator. In our reconstruction of the target, we employ gradient descent (GD) to iteratively minimize the error between experimental and synthetic patterns propagated from proposed target structures. By implementing the propagator in PyTorch, we leverage the automatic differentiation and GPU acceleration for the GD fit and at the same time obtain a differentiable physically-based loss function for unsupervised training of inversion or surrogate models. For a classical fit, we sample many different initial values for parameters, such as target asymmetry, to find the global minimum, leveraging batch-parallelism. A data-driven model to predict initial conditions close to actual minima can be trained in an unsupervised manner using our pipeline.

Methylammonium lead tribromide (MAPbBr3) stands out as the most easily grown wide-bandgap metal halide perovskite. It is a promising semiconductor for room-temperature gamma-ray (γ-ray) spectroscopic detectors, but no operational devices have been realized. This can be largely attributed to a lack of understanding of point defects and their influence on detector performance. Here, through a combination of crystal growth design and defect characterization, including positron annihilation and impedance spectroscopy, the presence of specific point defects have been identified and correlated to detector performance. Methylammonium (MA) vacancies, MA interstitials, and Pb vacancies were identified as the dominant charge trapping defects in MAPbBr3 crystals, while Br vacancies caused doping. The addition of excess MABr reduced the MA and Br defects and so enabled the detection of energy-resolved γ-ray spectra using a MAPbBr3 single crystal device. Interestingly, the addition of formamidinium cations, which converted to methylformamidinium (MFA) cations by reaction with MA+ during crystal growth further reduced MA defects. This enabled an energy resolution of 3.9% for the 662 keV 137Cs line using a low bias of 100 V. The work provides direction toward enabling further improvements in wide-bandgap perovskite-based device performance by reducing detrimental defects.

Accurate estimation of contaminant transport in cementitious material using numerical tools plays a key role in the risk assessments of nuclear waste disposal. At the pore scale, the increase of microbial activity, such as microbially induced calcite precipitation on cementitious material, causes changes in solid surface topography, pore network geometry, and pore water chemistry, which affect contaminant transport at the core scale and beyond. Consequently, a meaningful estimation of contaminant migration in the subsurface requires a pore-scale investigation of the influence of microbial activity on transport processes. In this study, a pore-scale reactive transport model is presented to simulate the physicochemical processes resulting from microbially induced calcite precipitation on a cement surface. Numerical investigations focus on modeling the reactive transport in a two-dimensional flow-through cell. The model results are validated by experimental data showing an increase in pH and a decrease in calcium concentration due to microbially induced calcite precipitation. Our results show heterogeneous calcite precipitation under transport-limited conditions and homogeneous calcite precipitation under reaction-limited conditions, resulting in non-uniform and uniform changes in the material surface topography. Moreover, power spectral density analysis of the surface data demonstrates that microbially induced calcite precipitation affects the surface topography via both general changes over the entire frequency and local modifications in the high-frequency region. The sensitivity studies provide a comprehensive understanding of the evolution of surface topography due to the microbially induced calcite precipitation at the pore scale, thus contributing to an improved predictability of contaminant transport at the core scale and beyond.

The demand for efficient and reliable battery materials has increased with the growing development of electric vehicles and renewable energy storage systems. Understanding the surface properties of battery materials, is crucial for optimizing battery performance. In this study, the Inverse Gas Chromatography-Surface Energy Analyser (iGC-SEA) is employed to analyse the surface characteristics of both anode and cathode materials. In this way, a comprehensive insight into their dispersive and specific surface energy behaviour is obtained, particularly looking at the impact of temperature, surface properties and surface heterogeneity, which are crucial parameters that affect battery performance.

Die für Reflexion und Dämpfung von Kurzwellen verantwortliche Elektronenkonzentration in der Ionosphäre hängt stark von der solaren Aktivität ab. Diese wird maßgeblich vom 11-jährigen Schwabezyklus des Sonnenmagnetfeldes bestimmt, weist aber auch kürzere Perioden von einigen hundert Tagen und längere Perioden von etwa 60 bis 200 Jahren auf. Üblicherweise wird die dominante Magnetfeld-Periode von sonnenähnlichen Sternen durch das Modell eines alpha-Omega-Dynamos beschrieben. Aber was verursacht die historisch gut belegte Phasenstabilität dieses Oszillators, und woher kommen die scharfen Peaks im Spektrum der kurzen und langen Perioden? Im Vortrag wird ein modifiziertes Modell des Sonnendynamos vorgestellt, welches alle beobachteten Perioden in konsistenter Weise beschreibt. Die Phasenstabilität des Schwabezyklus wird dabei auf die Triggerung von Magneto-Rossby-Wellen in der solaren Tachokline durch die Gezeitenwirkung von Venus, Erde und Jupiter zurückgeführt. Für die Erklärung der langperiodischen Gleissberg- und Suess-de Vries-Zyklen muss zusätzlich die rosettenförmige Bewegung der Sonne um das Schwerezentrum des Sonnensystems berücksichtigt werden.

Background: Prostate cancer (PCa) is the second most commonly occurring cancer in men and the fourth most common cancer overall, with around 1.4 million new cases in 20201. The prostate-specific membrane antigen (PSMA) is a well-known marker for PCa and its metastases. [99mTc]TcO-ABX474 ([99mTc]TcO-1: Kd= 7.2 ± 1.7 nM, see Fig. 1) is a novel PSMA-binding radioligand that has demonstrated promising radiopharmacologic properties in preclinical SPECT studies in LNCaP-tumor bearing mice3. The tumour-to-background ratio was found to be higher than that of [99mTc]Tc-PSMA-I&S and comparable to that of [68Ga]Ga-PSMA-11 PET/CT imaging. During the development of the radiosynthesis of [99mTc]TcO-ABX474 it has been shown that beside initial incubation at room temperature, elevated temperatures are beneficial to achieve a high radiochemical purity (RCP). However, it was observed that the heating step is accompanied by degradation of unreacted amounts of the precursor ABX474. The objective of this study was to identify the precursor’s degradation products, present in [99mTc]TcO-ABX474 preparations, and to investigate their impact on the radioligand’s imaging characteristics.

Methods: According to a developed procedure3, [99mTc]TcO-ABX474 was synthesised starting from the precursor ABX474 (50 µg, 26.1 µM) and Na[99mTc]TcO4 (0.2 – 7 GBq) in saline (Vtotal: 1.36 mL). In presence of SnCl2 (1 µg in 0.01 M HCl), calcium α-D-heptagluconate (10 µg) and D-mannitol (1 mg), the reaction solution was incubated at r.t. for 20 min and subsequently heated at 80°C for another 20 min. Reaction monitoring and quality control were performed by radio-HPLC, including UV detection for quantification of the precursor ABX474. In addition, preparations were carried out under similar conditions but using increased concentrations of ABX474 (10-fold: 261 µM and 100-fold: 2.6 mM), and without Na[99mTc]TcO4. The mixtures obtained were analysed by LC-MS (Q-Exactive® Plus, Thermo Scientific). In addition, the biodistribution of [99mTc]TcO-ABX474 was investigated in SPECT studies in LNCaP tumour-bearing mice when co-administered with precursor or its degradation products.

Results: During the synthesis of [99mTc]TcO-ABX474 (RCP: 97.0  1.8 %, N = 28) the initial concentration of the precursor ABX474 decreased by 79 % (from 26.1 µM to 5.8  2.0 µM, N = 7), mainly during the heating period at 80 °C. One of the main products detected was identified as the reduced S-S-bridged form of ABX474 (2, Ki= 12.8  6.4 nM, see Fig. 1). By means of LC-MS further main degradation pathways were identified: cleavage of both mercapto(gem-dimethyl)ethyl units (3), oxidation of one mercapto group (4), and dimer formation via S-S bond with loss of two mercapto(gem-dimethyl)ethyl groups (5). In LNCaP-tumor bearing mice (bw: 35 – 40 g), a product dose with an additional amount of the precursor ABX474 (7.4 nmol, corresp. to quantities if heating were omitted) displayed a decrease of radioligand uptake in the tumour by 51 %, compared to the standard radioligand preparation (remaining precursor: 1–2 nmol). Investigations on the influence of degradation products of the precursor ABX474 revealed that simultaneous administration of highly increased amounts (corresp. to 30.5 and 305 nmol in total) resulted in a blockade of radioligand uptake in the tumor by 66% and 89%, respectively. The calculated blocking efficiency of the mixture of degradation products was 68 % lower than that of the precursor ABX474.

Discussion & Conclusion: In the course of the preparation of [99mTc]TcO-ABX474 the additional heating step led to a decrease of surplus quantities of the precursor ABX474, which appears beneficial for SPECT imaging. However, only the chelator unit was affected by degradation, indicating that the resulting products are potentially PSMA-affine, as it has been demonstrated for 2. In our SPECT studies, even with increased amounts of degradation products (30.5 nmol) the blockade of radioligand uptake in the tumour remained in a similar range compared to the precursor ABX474 (7.4 nmol), when present in amounts as expected by omitting of the heating step (66 % vs. 51 %). The lower blocking efficiency observed for the mixture of degradation products indicates that the heating step within the preparation may help to minimise potential blocking effects in SPECT measurements. Further studies, such as the synthesis or isolation of ABX474 degradation products and the determination of their affinities to PSMA, are planned to further elucidate the effects of the product matrix.

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

References:

1 https://www.wcrf.org/cancer-trends/worldwide-cancer-data/ (accessed 31-01-2024)
2 Debnath, S.; Zhou, N.; McLaughlin, M.; Rice, S.; Pillai, A.K.; Hao, G.; Sun, X. PSMA-Targeting Imaging and Theranostic Agents - Current Status and Future
Perspective. Int. J. Mol. Sci. 2022, 23, 1158
3 Lis, A. et al., EPO Patent Application EP4282438, 23/05/2022

Competing magnetic interactions, frustration-driven quantum fluctuations, and spin correlations offer an ideal route for the experimental realization of emergent quantum phenomena with exotic quasiparticle excitations in three-dimensional frustrated magnets. In this context, trillium lattice, wherein magnetic ions decorate a three-dimensional chiral network of corner-shared equilateral triangular motifs, provides a viable ground. Herein, we present the crystal structure, dc and ac magnetic susceptibilities, specific heat, electron spin-resonance (ESR), muon spin-relaxation (μSR) results on the polycrystalline samples of K₂CrTi(PO₄)₃ wherein the Cr³⁺ ions form a two-coupled trillium lattice. The Curie-Weiss fit of the magnetic susceptibility data above 100 K yields a Curie-Weiss temperature θ_CW = −23 K, which indicates the presence of dominant antiferromagnetic interactions between S = 3/2 moments of Cr³⁺ ions. For temperatures below 40 K, the Curie-Weiss temperature is reduced to θCW = −3.5 K, indicative of the appearance of subdominant ferromagnetic interactions. The specific heat measurements reveal the occurrence of two consecutive phase transitions, at temperatures T_L = 4.3 K and T_H = 8 K, corresponding to two different magnetic phases. Additionally, it unveils the existence of short-range spin correlations above the ordering temperature T_H. The power-law behavior of ESR linewidth suggests the persistence of short-range spin correlations over a relatively wide critical region (T – T_H)/T_H > 0.25 in agreement with the specific heat results. The μSR results provide concrete evidence of two different phases corresponding to two transitions, coupled with the critical slowing down of spin fluctuations above T_L and persistent spin dynamics below T_L, consistent with the thermodynamic results. Moreover, the μSR results reveal the coexistence of static and dynamic local magnetic fields below T_L, signifying the presence of complex magnetic phases owing to the entwining of spin correlations and competing magnetic interactions in this three-dimensional frustrated magnet.

We have, in-situ, prepared and measured the temperature dependence of thermopower S(T) and resistance R(T) of Bi₂Te₃ topological insulator (TI) thin films in the amorphous and crystalline phase. Samples were prepared by sequential flash-evaporation at liquid ⁴He temperature. The S(T) in the amorphous phase is negative and much larger compared to other known amorphous materials, while in the crystalline phase it is also negative and behaves linearly with the temperature. The resistivity ρ(T) in the amorphous phase shows a semiconducting like behavior that changes to a linear metallic behavior after crystallization. S(T) an ρ(T) results in the crystalline phase are in good agreement with results obtained both in bulk and thin films reported in the literature. Linear behavior of the ρ(T) for T >15 K indicates the typical metallic contribution from the surface states as observed in other TI novel materials. The low temperature conductivity T <10 K exhibits logarithmic temperature dependent positive slope κ ≈ 0.21, indicating the dominance of electron-electron interaction (EEI) over the quantum interference effect, with a clear two dimensional nature of the contribution. Raman spectroscopy showed that the sample has crystallized in the trigonal R3m space group. Energy-dispersive x-ray spectroscopy reveales high homogeneity in the concentration and no magnetic impurities introduced during preparation or growth.

Structure and magnetic properties of layered GdMn₂(Ge_1-xSix)₂ (0 ≤ x ≤ 1) compounds were studied. All the compounds crystallize in the tetragonal ThCr₂Si₂-type structure. It was shown by magnetization measurements at low temperature on quasi-single crystals that, with increasing Si concentration, the easy magnetization direction reorients from the c-axis to the basal plane. The spin reorientation occurs via an angular phase. A model of three magnetic sublattices coupled by negative intersublattice exchange interactions was used to describe the field dependences of the magnetization. For GdMn₂Ge₂ and GdMn₂(Ge_0.9Si_0.1)₂ in the fields applied along the c-axis, seven different magnetic structures were predicted, including two angular structures considered for the first time. The model explains formation of angular magnetic structures in zero field in GdMn₂(Ge_1-xSi_x)₂ system by taking into account magnetic anisotropy of Mn sublattices with a positive anisotropy constant K₁ and negative K₂.

Magnetic refrigeration (MR) based on the magnetocaloric effect (MCE) has been recognized as an environmentally benign and energy-efficient cooling technology. Exploring suitable magnetocaloric materials is a crucial prerequisite for practical MR applications. We have herein provided a systematic investigation of the crystal structure, microstructure, electronic structure, magnetic phase transition, critical behavior, and MCE of the GdCoC compound featuring excellent cryogenic magnetocaloric performance by means of experimental determination and theoretical calculation. The GdCoC compound is crystallized in a simple layered tetragonal crystal structure with a P4₂/mmc space group and undergoes two successive ferromagnetic (FM) transitions along with a low-temperature weak antiferromagnetic (AFM) transition under low magnetic fields. Density functional theory calculations confirms the FM coupling of the Gd and Co intra-sublattice interactions, whereas AFM coupling for their inter-sublattice interaction. The magnetic transitions are merged in to one under high magnetic fields which has been confirmed to be second-order type and its critical behavior can be understood in the framework of tricritical mean-field model, whereas the low-temperature weak AFM transition is belonging to the first-order type. The excellent magnetocaloric performance of the GdCoC compound was identified by the parameters of magnetic entropy change, adiabatic temperature change, temperature-averaged entropy change, relative cooling power, and refrigerant capacity, which are superior to most of the well-known magnetocaloric materials with similar working temperatures, making it attractive for practical cryogenic MR applications.

The effects of thermal convection on turbulence in accretion discs, and particularly its interplay with the magnetorotational instability (MRI), are of significant astrophysical interest. Despite extensive theoretical and numerical studies, such an interplay has not been explored experimentally. We conduct linear analysis of the azimuthal version of MRI (AMRI) in the presence of thermal convection and compare the results with our experimental data published before. We show that the critical Hartmann number (Ha) for the onset of AMRI is reduced by convection. Importantly, convection breaks symmetry between m=±1 instability modes (m is the azimuthal wavenumber). This preference for one mode over the other makes the AMRI-wave appear as a ``one-winged butterfly''.

Water electrolysis offers a way to produce hydrogen from renewable electrical energy.
However, the details of gas evolution have a major impact on the energy efficiency of the process,
as gas bubbles growing at the electrodes or floating in the electrolyte cause overvoltages and losses.
It is therefore desirable to improve our understanding of gas evolution in order to further improve
electrolysis processes.
Gas evolution is influenced by a number of aspects, including electrolyte supersaturation and constitution,
nucleation and wetting at the electrode, electrolyte flow, interfacial flow and capillary effects,
coalescence with neighboring gas bubbles as well as temperature and electric fields.
The presentation will summarize the knowledge gained in recent years, based on own work and recent literature.

Hydrogel-based injectable drug delivery systems provide temporally and spatially controlled drug release with reduced adverse effects on healthy tissues. Therefore, they represent a promising therapeutic option for unresectable solid tumor entities. In this study, a peptide-starPEG/hyaluronic acid-based physical hydrogel is modified with ferrocene to provide a programmable drug release orchestrated by matrix-drug interaction and local reactive oxygen species (ROS). The injectable ROS-responsive hydrogel (hiROSponse) exhibits adequate biocompatibility and biodegradability, which are important for clinical applications. HiROSponse is loaded with the two cytostatic drugs (hiROSponsedox/ptx) doxorubicin (dox) and paclitaxel (ptx). Dox is a hydrophilic compound and its release is mainly controlled by Fickian diffusion, while the hydrophobic interactions between ptx and ferrocene can control its release and thus be regulated by the oxidation of ferrocene to the more hydrophilic state of ferrocenium. In a syngeneic malignant melanoma-bearing mouse model, hiROSponsedox/ptx slows tumor growth without causing adverse side effects and doubles the relative survival probability. Programmable release is further demonstrated in a tumor model with a low physiological ROS level, where dox release, low dose local irradiation, and the resulting ROS-triggered ptx release lead to tumor growth inhibition and increased survival.

Somatostatin type 2 receptor (SSTR2) radionuclide therapy using β− particle-emitting radioligands has entered clinical practice for the treatment of neuroendocrine neoplasms (NENs). Despite the initial success of [177Lu]Lu DOTA-TATE, theranostic SSTR2 radioligands require improved pharmacokinetics and enhanced compatibility with alternative radionuclides. Consequently, this study evaluates the pharmacokinetic effects of the albumin binding domain cLAB4 on theranostic performance of 67Cu labeled NODAGA-TATE variants in an SSTR2-positive mouse pheochromocytoma (MPC) model.
Methods: Binding, uptake, and release of radioligands as well as growth-inhibiting effects were characterized in cells grown as monolayers and spheroids. Tissue pharmacokinetics, absorbed tumor doses, and projected human organ doses were determined from quantitative SPECT imaging in a subcutaneous tumor allograft mouse model. Treatment effects on tumor growth, leukocyte numbers, and renal albumin excretion were assessed.
Results: Both 64Cu- and 67Cu-labeled versions of NODAGA-TATE and NODAGA-cLAB4 TATE showed similar SSTR2 binding affinity, but faster release from tumor cells compared to the clinical reference [177Lu]Lu DOTA-TATE. The bifunctional SSTR2/albumin-binding radioligand [67Cu]Cu NODAGA-cLAB4 TATE showed both an improved uptake and prolonged residence time in tumors resulting in equivalent treatment efficacy to [177Lu]Lu DOTA-TATE. Absorbed doses were well tolerated in terms of leukocyte counts and kidney function.
Conclusion: This preclinical study demonstrates therapeutic efficacy of [67Cu]Cu NODAGA-cLAB4 TATE in SSTR2-positive tumors. As an intrinsic radionuclide theranostic agent, the radioligand provides stable radiocopper complexes and high sensitivity in SPECT imaging for prospective determination and monitoring of therapeutic doses in vivo. Beyond that, 64Cu- and 61Cu-labeled versions offer possibilities for pre- and post-therapeutic PET. Therefore, NODAGA-cLAB4-TATE has the potential to advance clinical use of radiocopper in SSTR2-targeted cancer theranostics.

Electrochemical system requires catalysts based on critical raw materials to improve their performances, especially high temperature water electrolyzers (HTELs) contain valuable fine particles such as rare earth elements, strontium, scandium, and nickel.
While many studies are working towards the scale-up of hydrogen production using water electrolysis and it is therefore important to investigate the recycling process of catalyst materials used in HTELs, there has been a lack of studies on mechanical recycling for fine particles.
In this study, we characterized the model particle mixture consisting of Nickel oxide (NiO), Lanthanum strontium manganite (LSM), Yttria stabilized zirconia (YSZ), and Zirconium oxide (ZrO2). Different ceramic materials used in a HTEL cell have a similar wettability. The various ceramic materials used in HTEL cells generally have similar wettability (hydrophilicity) and it can be selectively changed by exploiting their surface charge and adding surfactants. There is a specific pH range (pH 9 - 11) where the surface charge of NiO and LSM is opposite to that of ZrO2 and YSZ, and the modification of its hydrophobicity is successfully reached by using cationic and anionic surfactants. During our research, we observed that the LSMs exhibited ferromagnetism that was different from the rest of the material and they could be selectively separated later by magnetic separation. With different combinations of surfactant, dispersant, and pH, particles can be selectively separated by using particle liquid-liquid extraction.
This study would provide the design of the mechanical separation study for the end-of-life HTEL recycling stream.

Self-diffusion in amorphous germanium is studied at temperatures between 325 and 370 °C utilizing amorphous isotopically controlled germanium multilayer structures. The isotope multilayer is epitaxially grown on a single crystalline germanium-on-insulator structure by means of molecular beam epitaxy and subsequently amorphized by self-ion implantation. After heat treatment, the diffusional broadening of the isotope structure is measured with time-of-flight secondary ion mass spectrometry. The temperature dependence of self-diffusion is accurately described by the Arrhenius equation with the activation enthalpy Q = (2.21 ± 0.12) eV and pre-exponential factor D0 = (2.32 +20.79 −2.10 ) cm2 s−1. The activation enthalpy equals the activation enthalpy of solid phase epitaxial recrystallization (SPER). This agreement suggests that self-diffusion in amorphous germanium is similar to SPER, also mainly mediated by local bond rearrangements. Classical molecular dynamics simulations with a modified Stillinger–Weber-type interatomic potential yield results that are consistent with the experimental data and support the proposed atomic mechanism.

We design a novel class of Janus structures PbXY (X,Y = F, Cl, Br, I) and propose it for the solar mediated photocatalytic water splitting hydrogen production and for the bulk photovoltaic effect. The relaxed layers show a strong variation of the structural parameters which is due to the electronegativity of the halide atoms. The stability of the Janus structures is investigated using formation energy, phonon spectra, elastic constants and Ab-Initio Molecular Dynamics simulations. Using differential charge density calculations and Bader charge analysis, it is found that the atomic bonds may have covalent or ionic character, which depends on the halide atoms in top and bottom layers of the Janus structure. Electronic structure calculations are performed using the GGA functional and the more precise HSE functional. From the band structure, band gap and effective masses of electrons and holes are determined. The large difference between the mobility of both charge carriers as well as the built-in electrical dipole indicate beneficial conditions for charge separation and suppression of charge recombination. The calculated optical absorption spectra show that the Janus structures are suitablefor UV-visible light absorption. Based on VBM and CBM calculation using the HSE functional it is demonstrated that the novel PbXY Janus layers are suitable for water splitting reaction, i.e. for the use as a photocatalyst.

Technetium (Tc) is an inherent radioactive element with isotopes ranging from 85Tc to 120Tc [1]. Among them, 99Tc is the most environmentally relevant since it is a high yield fission product of 235U and 239Pu, and the daughter nuclide of metastable Tc-99 (99mTc) – the isotope most com-monly used for radiodiagnosis worldwide. 99Tc is a long-lived beta minus emitter (½ = 2.13∙105 years) and its aqueous speciation and migration behavior is influenced by the (physico-)chemical conditions (e.g., pH, presence of ligands, redox conditions, etc.). It is known that TcVIIO4 barely interacts with minerals and, thus, its migration in water is high. On the contrary, the mobility of TcIV is limited since it forms low soluble species (e.g., TcO2 or Tc-sulfides), sur-face complexes on minerals, and/or it is incorporated into the mineral structures [2]. Deepening our knowledge on Tc mobility is important for the safety assessment of a nuclear waste reposito-ry and for radioecology. Thus, several works focused on Tc aqueous speciation based on redox changes and the chemical composition of the solution, e.g., [3–5].
In this work, we have studied the speciation of KTcVIIO4 in carbonate solutions when it is elec-trochemically reduced at varying pH (8.2 – 10.0), Tc concentration (0.5 – 9.5 mM), carbonate concentration (5 – 1000 mM), and the applied potential. TcVII reduction was monitored in situ by UV-vis, by using a spectro-electrochemical cell. At 0.85 V a pink solution (λmax = 512 nm) was obtained, corresponding to a TcIV carbonate species [3], whereas reduction at 0.95 V yields a bluish green solution (λmax = 630 nm), associated with a TcIII carbonate complex [3]. Additional-ly, the obtained solutions were investigated by ex-situ 99Tc NMR. The −0.85 V specimen reveals a resonance at ~1600 ppm, characteristic for TcV [6]. In addition to the TcV signal mentioned above, the solution obtained at −0.95 V gives a further signal at ~152 ppm, which can be as-signed to the chemical shift range of TcIII [6].
These are unprecedented NMR data on aqueous Tc carbonate species, complemented by UV-Vis spectroscopic analysis. They advance the mechanistic understanding of Tc redox behavior, and help to improve safety and risk analyses for nuclear waste management.
Our current focus is on in-situ coupling NMR spectroscopy with electrochemical methods in or-der to monitor simultaneously the structural changes on redox active (radioactive) pollutants as a function of the redox conditions.

Acknowledgements:

The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072) [7]).

[1] E.V. Johnstone, J. Chem. Educ. 320–326, (2017).
[2] A.H. Meena, Env. Chem Lett. 241–263, (2017).
[3] J. Paquette, Can. J. Chem. 2369–2373, (1985).
[4] M. Chotkowski, J. Electroanal. Chem. 83–90, (2018).
[5] D.M. Rodríguez, Inorg. Chem. 10159–10166, (2022).
[6] V.A. Mikhalev, Radiochem. 319–333, (2005).
[7] https://www.hzdr.de/db/Cms?pNid=1375, vis 18.06.2024

Radiotherapy of prostate cancer (PC) can lead to the acquisition of radioresistance through molecular mechanisms that involve, in part, cell adhesion-mediated signaling. To define these mechanisms, we employed a DU145 PC model to conduct a comparative mass spectrometry-based proteomic analysis of the purified integrin nexus, i.e., the cell-matrix junction where integrins bridge assembled extracellular matrix (matrisome components) to adhesion signaling complexes (adhesome components). When parental and radioresistant cells were compared, the expression of integrins was not changed, but cell radioresistance was associated with extensive matrix remodeling and changes in the complement of adhesion signaling proteins. Out of 72 proteins differentially expressed in the parental and radioresistant cells, four proteins were selected for functional validation based on their correlation with biochemical recurrence-free survival. Perlecan/heparan sulfate proteoglycan 2 (HSPG2) and lysyl-like oxidase-like 2 (LOXL2) were upregulated, while sushi repeat-containing protein X-linked (SRPX) and laminin subunit beta 3 (LAMB3) were downregulated in radioresistant DU145 cells. Knockdown of perlecan/HSPG2 sensitized radioresistant DU145 RR cells to irradiation while the sensitivity of DU145 parental cells did not change, indicating a potential role for perlecan/HSPG2 and its associated proteins in suppressing tumor radioresistance. Validation in androgen-sensitive parental and radioresistant LNCaP cells further supported perlecan/HSPG2 as a regulator of cell radiosensitivity. These findings extend our understanding of the interplay between extracellular matrix remodeling and PC radioresistance and signpost perlecan/HSPG2 as a potential therapeutic target and biomarker for PC.

The interactions of actinides, such as uranium, with corrosion products in the near-field of a ge-ological repository are of concern regarding its safety assessment. The main corrosion product of the zircaloy cladding material is ZrO₂, which represents one of the first barriers for interac-tions with radionuclides in particular during the period of interim storage.[1] Consequently, un-derstanding the molecular interactions between actinides and ZrO₂ under oxidizing conditions is of particular importance in the context of early-failure scenarios for the interim storage of spent nuclear fuel in containers in the vicinity of nuclear power plants.
In situ vibrational spectroscopy has been used as a strong tool for the monitoring of the for-mation of actinide’s surface complexes in an aqueous environment.[2] The setup of a flow through experiment allows data acquisition of a stationary ZrO₂ phase during the course of the sorption and desorption reactions in real time, with a sub minute time resolution and under well-defined atmospheric conditions. Hence, we investigated the surface species of U(VI) at the ZrO₂ surface under anoxic and oxic conditions as well for the study of the impact of atmospherically derived carbonate on the surface speciation at neutral pH values.
From the frequencies of the bands representing the vibrational modes of the carbonate and ura-nyl ions, the formation of ternary U(VI)-carbonate surface complexes was deduced. The car-bonate ligands most likely bidentately orientated to the uranium moiety that in turn directly co-ordinated to the ZrO₂ surface.
The desorption of the ternary surface complex was induced by flushing the solid phase includ-ing the ternary surface species with background electrolyte. The spectra recorded during this re-action step revealed only a poor reversibility of the sorption reaction indicating a predominant inner sphere complexation under the prevailing conditions.
With respect to the circumneutral pH level, spectroscopic investigations are often hampered by the instability of aqueous U(VI) solutions at a concentration level required for an accurate sig-nal-to-noise ratio. This might interfere with the formation of surface precipitation due to the presence of colloids in the aqueous solutions. Here, we conducted a series of in situ IR sorption experiments to demonstrate the growing contribution of solid formation beneath ongoing sorp-tion processes using metastable U(VI) solutions. The spectra revealed an increased contribution of surface precipitation in dependence of the age of the solution applied, which was deduced from the spectral changes observed from vibrational modes of both carbonate and uranyl ions.

As water electrolysis technology becomes more established, the development of the recycling processes for critical raw materials is important. This study presents the investigation of the mechanical recycling processes of polymer electrolyte membrane (PEM) electrolyzers containing noble metals. According to a previous study, the representative materials of the catalyst-containing particles showed a clear difference in their hydrophobicity, and effective separation was achieved in binary particle systems. This study demonstrates the impact of ionomers used in catalytic inks on the separation process. An ionomer is not only used to separate two electrodes in the form of a solid film but is also used in the process of manufacturing catalyst ink in liquid form acting as a binder. The surface characterizations of ionomer-containing particles and the selective separation process exploiting liquid-liquid extraction allow us to estimate particle behaviors. The results showed that the presence of ionomer had a negligible effect on the wettability of the cathode material, regardless of its content, but changed the wettability of the anode material from hydrophilic to partially hydrophobic.

As one of the promising hydrogen production technologies, the development of water electrolysis systems including recycling of their functional components is actively investigated. However, the focus lies on energy and chemicals intensive metallurgical operations and less on mechanical separation processes in most studies. Here, an innovative surfactant-based separation process (using CTAB and SDS) is being investigated to contribute to developing a selective physical separation process for ultrafine particles used in high temperature water electrolyzers (composed of NiO, LSM, ZrO2, and YSZ). Their different surface charge in alkaline solutions influences the adsorption of surfactants on particle surfaces as well as the modification of the particulate wettability, which is a key separation feature. Through the observations of changes in surface charge and wetting behavior in the presence of surfactants, a feasibility of liquid-liquid particle separation (LLPS) is evaluated. The performance of LLPS with model particle mixtures shows a potential of selective separation with recovery of NiO in the organic phase, while the rest of the particles remain in the aqueous phase. The perovskite LSM is not considered in this system because it shows a high possibility of being recovered by magnetic separation. The proposed process can be further optimized by increasing the phase separation stages, and further research is needed on the NiO phase, which showed exceptional behaviors in presence of the surfactants.

High-Energy Resolution Fluorescence Detection (HERFD) is a powerful technique for the exploration of the properties and state of actinides, lanthanides, and other elements [1, 2]. The principles of HERFD are based on the selection of emitted fluorescence with an X-ray emission spectrometer with the help of crystal analyzers. The X-ray emission spectrometer recently developed at ROBL [1] is equipped with 5 crystal analyzers and has 2 possible configurations (0.5m and 1m). The main ad-vantages of HERFD for actinides can be summarized as:

1) Near-zero background counts of HERFD allow to decrease in the detection limit on the one hand and to study complex systems with the main constituents of the matrix with overlapping fluorescence and/or the scattering signal on the other hand. Both XANES and EXAFS spectra can be successfully measured in samples for which total fluorescence measurements are not efficient. For example, the Ce state (down to ppb level) in the presence of La or Zr can be characterized by HERFD-XANES.
3) The use of HERFD at M4,5 edges in actinides (i.e. tender X-rays) allows fingerprinting of the oxi-dation state of the actinides. The maximum of M4,5 HERFD-XANES spectra is shifted by energy with oxidation state [3].
4) Better energy resolution of HERFD-XANES spectra improves the accuracy of XANES quantita-tive analyses. For example, the Ce(III)/Ce(IV) mixture with low Ce(IV) can be quantified by HERFD-XANES.
5) Energy position of the fluorescence lines (and especially the Kβ ones) is sensitive to the spin state and the ligands. Thus, the XAS spectra obtained by measuring these lines are spin or ligand sensi-tive. For example, HERFD-XANES at the Lβ5 emission line of U allows to resolve the crystal field splitting in UO2 [4].
6) With the help of an emission spectrometer, other spectroscopic techniques such as valence-to-core XES or RIXS can be applied to better discriminate between the different ligands in the first coordina-tion sphere of actinides.
Recently developed in situ temperature cell at ROBL allows to perform first in situ experiments with U compounds and to probe U M4 edge with HERFD under high T. The first results obtained at ROBL allow revising the current state of knowledge on the temperature-dependent transformations in U compounds.
[1] Scheinost, A. C. et al (2020) J. Synchrotron Rad. 28, 333 – 349.
[2] Proux O. et al. (2017) Journal of Environmental Quality, 2017, 46, 1146–1157.
[3] Kvashnina K.O.; Butorin S. M.; Chemical Communications, 2022, 58, 327–342.
[4] Kvashnina et al. (2014) J. of Elect. Spectros. and Relat. Phenom. 194 (2014) 27.

Uranium (U) is of radioecological relevance owing to its natural occurrence, but also with regard to legacies of former U mining activities and to the long-term safety assessment for high-level radioactive waste repositories. It is a radiotoxic and chemotoxic actinide with a greater risk of chemical toxicity. In biogeosphere context, the two forms of importance are tetravalent U(IV) and hexavalent U(VI). U(IV) prevails in anaerobic environments, is hardly water soluble and hence less mobile and less toxic. Conversely, U(VI) is the most stable form of U, in aqueous media forming the uranyl(VI) ion, UO22+, being soluble and thus highly mobile and, eventually, much better bioavailable.

Malic acid (MA), along with citric and succinic acid, is one of the most abundant exudates of plants. It plays several critical roles in plant metabolism and homeostasis, including respiration and energy generation, plant nutrition, nitrogen fixation, metal tolerance, and serving as a signaling molecule for beneficial microbes [1, 2]. MA is a hydroxydicarboxylic acid, forming two stereoisomers, D- and L-isomer, the latter of which naturally occurring in biological systems [3]. The pKa values for the carboxyl groups are 3.4 and 5.1, while the pKa value for the hydroxyl group is approximately 14.5 [4-6].

MA is a notable chelating agent for a wide variety of metal ions [7]. Therefore, interactions between actinides, such as U, and MA are expected when they coexist in the soil. The complexation of uranyl(VI) with MA has been studied and characterized, revealing that the most common uranyl(VI)-MA complex exhibits a dinuclear structure [8].

The complexation of U(VI) with MA significantly impacts U solubility in soil, its potential uptake into plants and interaction with microorganisms. For the prediction of the U(VI)–MA complexation, reliable thermodynamic data based on a molecular process understanding are necessary. These data will contribute to a reliable assessment of the transport and transfer of U in the environment and for the development of suitable bioremediation methods.

As part of a superior project, we studied the complexation of U(VI) with MA by time-resolved laser-induced fluorescence spectroscopy (TRLFS), isothermal titration calorimetry (ITC), nuclear magnetic resonance spectroscopy (NMR) and density functional theory (DFT). TRLFS was performed to study the U speciation and species distribution in solutions with MA, and showed three main U species in solution as a function of MA concentration: the free uranyl(VI) ion, a 2:1 and a 2:2 uranyl(VI) : MA complex that were confirmed by NMR spectroscopy. The occurrence of the different species changed with the variation of the U(VI) : MA ratio, with the 2:1 and 2:2 complexes dominating at U(VI) : MA ratios of >1 or <1, respectively. Comprehensive NMR spectroscopic measurements were performed to study the structure and stoichiometry of the complexes in solution under various conditions to support the TRLFS and ITC data interpretation. The results show the 2:2 uranyl(VI)–MA complex is the most abundant in a broad pH range from 3–7 even for concentrations as low as 10 µM. The 2:1 uranyl(VI)–MA was also found at lower pH values (2–4). DFT calculation helped to interpret NMR spectra and to unambiguously assign the individual species. Thermodynamic data were established by ITC. New binding affinities and stability constants for both complexes (2:2 and 2:1 complexes) in 0.1 M NaClO4 solutions were determined.

The present results enhance our knowledge of U(VI) interaction with malic acid, improve the thermodynamic database, and contribute to understanding the role of small organic molecules in the defense mechanisms of plants towards radionuclides.

This study is funded by the German Ministry of Education and Research under contract No. 15S9437C.

References:

[1] Kamilova et al. (2006). Molecular Plant-Microbe Interactions 19(3): 250-256.
[2] Schulze et al. (2002). Plant and Soil 247: 133-139.
[3] Lee et al. (2019). Comprehensive Biotechnology, 3rd ed.: 172-187.
[4] Max and Chapados (2002). The Journal of Physical Chemistry A 106.27: 6452-6461
[5] Søltoft-Jensen and Hansen (2005). Emerging Technologies for Food Processing: 387-416.
[6] Silva et al. (2009). BioMetals 22(5): 771-778.
[7] Brittain (2001). Profiles of drug substances, Excipients and Related Methodology 28: 153-195.
[8] Unruh et al. (2013). Inorganic Chemistry 52(17): 10191-10198.

Bei der zyklotronbasierten Herstellung radiopharmazeutisch interessanter Radionuklide entstehen neben dem Nutznuklid auch radioaktive Nebenprodukte. Im vorliegenden Fall waren Reststoffe, die diese Radionuklide enthielt, entsprechend der novellierten Strahlenschutzverordnung nicht freigebbar, da der entsprechende Freigabewert in der Anlage 4, Tabelle 1 fehlte.
Ein Beispiel für ein solches Radionuklid ist Re-183, welches bei der Produktion von F-18 unter der Verwendung von HAVAR®-Folien entsteht. Für dieses Radionuklid existierte kein Freigabewert.
Bei der täglichen Produktion von F-18 fallen kontaminationsverdächtige Reststoffe an, die freigegeben und entsorgt werden müssen. Daher ergab sich ein dringender Handlungsbedarf.
Im vorliegenden Fall wurde eine Freigabe im Einzelfall - das Radionuklid betreffend - angestrebt. Es galt die Einhaltung der 10 µSv nachzuweisen. Dazu wurde geprüft, auf welche Weise sich Freigabewerte errechnen oder ob ein vergleichbares Radionuklid als Ersatznuklid infrage kommt. Schlussendlich wurde ein Wert durch Literaturrecherche ermittelt und der entsprechende Antrag für insgesamt 56 Radionuklide gestellt. Dieser Antrag auf Freigabe im Einzelfall wurde positiv beschieden. Somit ist die Freigabe der radioaktiven Nebenprodukte möglich.
Mit In-Krafttreten der vierten Änderungsverordnung der Strahlenschutzverordnung im Jahr 2024 wurden die beantragten Radionuklide zu Teilen auch in die Anlage 4 Tabelle 1 der Strahlenschutzverordnung aufgenommen.

Exploring Geochemistry through High-Energy Resolution X-ray Absorption Spectroscopy. Invited Lecture about Synchrotron Facility ESRF and geochemistry applications for HERFD.

Mixed oxidation state of uranium is well described for U-O system [1]. In geochemistry, our knowledge of oxidation state of uranium present as a trace component in rocks and host minerals remains very limited. Whereas the oxidation/reduction of uranium is expected to be common in different geological contexts, the quantification of U(IV), U(IV) and U(V) in rocks and host minerals remains challenging. The recently developed synchrotron-based technique of high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy at U M₄ edge (3728 eV) opens new perspectives for fingerprinting the oxidation state of uranium at low U concentration (down to ppm level) [1]. The principles of HERFD are based on the selection of emitted fluorescence with an X-ray emission spectrometer equipped with crystal analyzers [2]. The maximum of M₄ HERFD-XANES spectra is shifted by energy with oxidation state. The chemical shift between various oxidation states U(IV)–U(V)–U(VI) is not linear, i.e. the shift between U(IV) and U(V) (1.5eV) is much greater than the one between U(V) and U(VI) (0.5 eV) (Figure 1). The coordination geometry may impact the energy shift only by 0.1 – 0.2 eV. Thus, the principal component analyses of HERFD-XAS spectra at U M4 edge is straightforward for accurate quantification of different oxidation states even if the pure structural end-members are not known. Our measurements of natural samples (black shales, volcanic glasses) and model systems (U-O system under high T) clearly show the presence of mixed oxidation states of U, i.e. U(IV)+U(V), U(V)+U(VI), U(IV)+U(VI) and U(IV)+U(V)+U(VI). Studying the oxidation state of U will improve our understanding of uranium geochemistry and the geochemical model of U reactivity and mobility in the environment.
[1] Kvashnina, K. et al. (2022) Chem. Commun. 58, 327 – 342.
[2] Scheinost, A. C. et al (2020) J. Synchrotron Rad. 28, 333 – 349.

Hydrothermal fluids have a very low mass fraction in the deep Earth (i.e., they are negligible in terms of mass balance); however, they exhibit high mobility, interact with rocks and magmas, and transport dissolved components, including H2. When rocks come into contact with aqueous fluids, chemical redox reactions can either generate or consume H2. The vast array of hydrothermal ore deposits attests to the inhomogeneity of the chemical and physical properties of the fluids and the deep crust and upper mantle. If some physical properties can be measured from the surface, the chemical properties remain unachievable for direct observations. Our current knowledge is derived from two sources: 1) detailed studies of rocks and minerals preserve their original state, and 2) in-situ measurements conducted on modeled systems during high-temperature and high-pressure experiments. Synchrotron-based X-ray spectroscopy techniques, such as HERFD-XANES spectroscopy, have proven to be powerful analytical tools for investigating the oxidation state of elements. Recently, our research group at the ROBL beamline employed the HERFD-XANES spectroscopy technique to characterize natural Fe minerals with sorbed H2. We discovered that the Fe state in the rock where H2 was sorbed differed from other H2-poor areas. To better understand the possible mechanisms of H2 concentrating at the depths, we are developing experimental and thermodynamic approaches to describe the vapor-liquid partitioning of H2. Solubility of H2 in the liquid H2O is low, but as the amounts of H2 rise by the water-rock interaction, the liquid will become saturated in dissolved H2 and further addition of H2 will result in the formation of a H2-rich vapor phase. Consequently, vapor-liquid immiscibility can be considered one of the primary mechanisms for the extensive production of H2 in the deep crust.

The complex behavior of uranium in natural environments is mainly controlled by the oxidation and reduction processes. The HERFD-XAS and HERFD-XRF measurements at U M4 edge open new perspectives for fingerprinting the oxidation state of uranium in natural samples in which U is concentrated (form own minerals) or present as a trace (down to ppm level). For numerous scientific fields such as geochemistry, biochemistry, and environmental geochemistry the knowledge of the oxidation state of uranium (U) present at the ppm level is of high importance. High-Energy Resolution Fluorescence Detection (HERFD) spectroscopy at U M4 edge is the most powerful method for the quantification of mixed oxidation states of U [2]. The main edge of the U M4 HERFD-XAS spectrum arises from the electronic transitions from the U 3d3/2 to 5f level, i.e. highly sensitive to the oxidation state (Figure 1). Even if the local atomic coordination of U may impact the energy maximum (generally by 0.1 – 0.2 eV), the principal component analyses of HERFD-XAS spectra at U M4 edge is straightforward for accurate quantification of different oxidation states even if the pure structural end-members are not known. In addition, the HERFD X-ray fluorescence (XRF) mapping at U M4 edge allows 2D visualization of U(IV), U(V) and U(VI) distribution and their relations. Thus, the HERFD-XAS and HERFD-XRF are exceptional techniques for studies focused on the U state and behavior in natural environments.

Technetium-99 is a long-lived fission product (2.13∙10⁵ years) of uranium-235 and plutonium-239, and therefore of great concern for the long-term safety management of nuclear waste. The migration of Tc in the environment is highly influenced by the redox conditions. Tc is expected to mainly occur as Tc(VII) under oxidizing conditions and as Tc(IV) under reducing conditions. The pertechnetate anion, Tc(VII)O₄⁻ is known to barely interact with mineral surfaces. The lack of retention mechanisms result in facile migration into groundwater and favors its entry in the biosphere. On the contrary, the formation of Tc(IV) limits the migration of Tc since it forms a low soluble solid (TcO₂) and/or species whose interaction with minerals is more favorable. In the last decades, Tc migration focused on the reduction of Tc(VII) to Tc(IV) by e.g., Fe(II), Sn(II) or S(−II) either present in solution, taking part in mineral structures [1], or metabolically induced by microbial cascades [2]. Most of the published studies deal with binary systems, i.e. studies of the interaction of Tc with a given reductant. However, the environment is a complex system with various components coexisting and influencing each other. Thus, Tc migration should not be studied only in a simple system. The young investigator group TecRad [3] studies the biogeochemical behavior of Tc upon interaction with: i) microorganisms, ii) metabolites, iii) Fe(II) minerals, and iv) Fe(II) minerals in presence of metabolites.
An fundamental part of this project addresses the implementation of new spectro-electrochemical in situ methods to monitor the behavior of Tc in solution and at interfaces as a function of the redox potential. With these tools, we aspire at characterizing the molecular structures of Tc species under a variable range of redox conditions, to deepen our understanding of the physico-chemical behavior of the pollutant.
Our goal is to generate valuable thermodynamic and structural data (complex formation constants, solubility constants of minerals, redox potentials and Tc distribution coefficients) that we will implement into a geochemical model to explain Tc environmental fate even under different redox conditions.

References:

[1] Pearce, C. et al. (2020). Sci. Total Env. 716: 132849. [2] Newsome, L. et al. (2014). Chem. Geol. 363: 164-184.[3] TecRad webpage: https://www.hzdr.de/db/Cms?pNid=1375 vis on February 9th 2023.

Acknowledgements:

The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072)).

Technetium (Tc) is an inherent radioactive element with isotopes ranging from ⁸⁵Tc to 1²0Tc [1]. Among them,99Tc is the most environmentally relevant since it is a high yield fission product of ²³⁵U and ²³⁹Pu, and the daughter nuclide of metastable Tc-99 (Tc-99m) – the isotope most used worldwide for radiodiagnosis. ⁹⁹Tc is a long-lived beta minus emitter (t½ = 2.13∙10⁵ years) and its aqueous speciation and migration behavior is influenced by the (physico-)chemical conditions (e.g, pH, presence of ligands, redox conditions, etc.). It is known that Tc(VII)O₄⁻ barely interacts with minerals and, thus, its migration in water is high. On the contrary, the mobility of Tc(IV) is limited since it forms low soluble species (e.g., TcO₂ or Tc-sulfides), surface complexes on minerals, and/or it is incorporated into the mineral structures [2]. Studying Tc mobility is a matter of concern for the safety assessment of the nuclear waste repository and radioecology. Thus, several works focused on Tc aqueous speciation based on redox changes and the chemical composition of the solution, e.g., [3–5].
In this work, we have studied the speciation of KTc(VII)O₄ in carbonate solutions when it is electrochemically reduced at varying 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 situ by UV-vis, by using a spectro-electrochemical cell. At –0.85 V a pink solution (λmax 512 nm) was obtained, corresponding to a Tc(IV) carbonate species [3], whereas reduction at –0.95 V yields a bluish green solution (λmax 630 nm), associated with a Tc(III) carbonate complex [3]. Additionally, the obtained solutions were then investigated by ⁹⁹Tc NMR. The −0.85 V specimen reveals a resonance at ~1600 ppm, which characteristic for Tc(V) [6]. The other solution yielded at −0.95 V, in addition to the aforementioned Tc(V) signal, gives rise to one additional signal at ~152 ppm, corresponding to the chemical shift range related to Tc(III) [6].
These are unprecedented NMR data on aqueous Tc carbonate species, complemented by UV-Vis spectroscopical analysis, advance the mechanistic understanding of Tc redox behavior, and help to improve safety and risk analyses for nuclear waste management.

References:

[1] E.V. Johnstone, J. Chem. Educ. (2017) 320–326. [2] A.H. Meena, Env. Chem Lett. (2017) 241–263 [3] J. Paquette, Can. J. Chem. (1985) 2369–2373 [4] M. Chotkowski, J. Electroanal. Chem. (2018) 83–90. [5] D.M. Rodríguez, Inorg. Chem. (2022) 10159–10166. [6] V.A. Mikhalev, Radiochemistry. (2005) 319–333.

Acknowledgements:

The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072)).

Recent decades have seen enormous progress in the experimental investigation of fundamental processes that are relevant to geophysical and astrophysical fluid dynamics. Liquid metals have proven particularly suited for such studies, partly owing to their small Prandtl numbers that are comparable to those in planetary cores and stellar convection zones, partly owing to their high electrical conductivity that allows the study of various magnetohydrodynamic phenomena. After introducing the theoretical basics and the key dimensionless parameters, we discuss some of the most important liquid-metal experiments on Rayleigh–Bénard convection, Alfvén waves, magnetically triggered flow instabilities such as the magnetorotational and Tayler instability, and the dynamo effect. Finally, we summarize what has been learned so far from those recent experiments and what could be expected from future ones.

In this paper, we present numerical and experimental results on helicity oscillations in a liquid-metal Rayleigh–Bénard convection cell with an aspect ratio of 0.5. While the numerical simulations use the finite volume library OpenFOAM, the experimental results are obtained by means of contactless inductive flow tomography. We find that helicity oscillations occur during transitions of flow states with different roll numbers that are characterized by significant changes in the Reynolds number. However, helicity oscillations are also observed when the number of rolls is constant and the Reynolds number is changing only very slowly. Notably, the helicity oscillations observed during the transient double-roll state exhibit characteristics remarkably similar to those associated with the Tayler instability, which points to a rather generic and universal character of this phenomenon. Helicity oscillations are also discussed as a possible mechanism for synchronizing the solar dynamo by tidal forces of the orbiting planets.

Lanthanides and actinides are emerging contaminants, but little is known about their uptake and distribution by plants and their interactions in the rhizosphere. To better understand the fate of these metals in plants, we assessed the bioassociation of 2, 20 and 200 µM Eu(III) by five hydroponically grown crops endemic to Europe. The metal’s concentration and its speciation was monitored by inductively coupled plasma mass spectrometry and laser spectroscopy, whereas root exudation was investigated by chromatographic methods. It has been shown, that Eu(III) bioassociation is a two-stage process, involving rapid biosorption followed by accumulation in root tissue and distribution to the stem and leaves. Within 96 h of exposure time, the plant induces a change of Eu(III) speciation in the liquid medium, from a predominant Eu(III) aquo species, as calculated by thermodynamic modelling, to a species with longer luminescence lifetime. Root exudates such as citric, malic, and fumaric acid were identified in the cultivation medium and affect Eu(III) speciation in solution, as was shown by a change in the thermodynamic model. These results contribute to a comprehensive understanding of the fate of lanthanides in the biosphere and provide a basis for further investigations with the chemical analogues Cm(III) and Am(III).

Einleitung
Wirtschaftliche und wissenschaftliche Fortschritte sind an eine gesicherte Versorgung von Technologiemetallen eng geknüpft. Um den wachsenden Bedarf auch mit heimischen Rohstoffen zu versorgen, werden Anstrengungen im Bereich des Recyclings und der Haldenaufbereitung unternommen. Beide Felder bieten einen Mehrfachnutzen, z. B. Müllreduktion bzw. Renaturierung und Schadstoffabbau.
Die Flotation, als ein sehr verbreitetes physikalisch-chemisches Trennverfahren für feinkörnige Feststoffe, wird hierfür auf Grund seiner guten Skalierbarkeit eingesetzt. Bei Flotation wird vereinfacht gesagt das gemahlene Ausgangsmaterial mit Wasser und speziellen Reagenzien vermischt und anschließend mit Luft beaufschlagt. Während dieses Prozesses bilden sich Blasen, an deren Oberfläche sich einige gewünschte Stoffe festsetzen und andere ausfallen. Damit wird das Ergebnis dieses komplexen Aufbereitungsprozesses durch eine Vielzahl von Parametern und deren Wechselwirkungen bestimmt.
Methode und Umsetzung
Für die chemischen und physikalischen Parameter von Aufbereitungsprozessen gilt es geeignete Sensoren bereitzuhalten, die den jeweiligen Anforderungen der Skalierung und Nutzung entsprechen. Während bei Industrieanwendungen ein geeignetes Sensorportfolio vorliegt, sind bei Laboranlagen Sensoren häufig zu groß, um ungestörte Strömung zuzulassen und zu ungenau, um Phänomene reproduzierbar zu beobachten.
Mit Hilfe der Siebdrucktechnik können Sensoren in der Größenskala von ….
Die Sensordaten werden anschließend über eine schnittstellenoffene Datenerfassung (DAQ) in einen Data Lake abgelegt, der neben der effizienten Datenspeicherung auch einen einfachen Zugriff auf die Informationen für die Auswertung und Sensorfusion zu Key-Performance-Indikatoren (KPI) erlaubt, Abbildung 1. Diese agglomerierte und einfache Repräsentation des komplexen Aufbereitungsprozesses erlaubt eine prädiktive Prozessregelung und eine aussagefähige Prozessvisualisierung. Dies wird durch Deep-Learning-Algorithmen …

As semiconductor devices approach dimensions at the atomic scale, controlling the compositional grading across hetero-interfaces becomes paramount. Particularly in nanowire axial heterostructures, which are promising for a broad spectrum of nanotechnology applications, the achievement of sharp hetero-interfaces has been challenging owing to peculiarities of the commonly used vapor-liquid-solid growth mode. Here, the grading of Al across GaAs/AlxGa1-xAs/GaAs heterostructures in self-catalyzed nanowires is studied, aiming at finding the limits of the interfacial sharpness for this technologically versatile material system. A pulsed growth mode ensures precise control of the growth mechanisms even at low temperatures, while a semi-empirical thermodynamic model is derived to fit the experimental Al-content profiles and quantitatively describe the dependences of the interfacial sharpness on the growth temperature, the nanowire radius, and the Al content. Finally, symmetrical Al profiles with interfacial widths of 2–3 atomic planes, at the limit of the measurement accuracy, are obtained, outperforming even equivalent thin-film heterostructures. The proposed method paves the way to advanced heterostructure schemes and a better exploitation of the nanowire platform; moreover, it is also considered expandable to other material systems and nanostructure types.

The holographic Einstein-Maxwell-dilaton model is employed to map state-of-the-art lattice 1
QCD thermodynamics data from the temperature (T) axis towards the baryon-chemical potential 2
(μB) axis aimed at gaining a warm equation of state (EoS) of deconfined QCD matter which can 3
be supplemented with a cool and confined part suitable for subsequent compact (neutron) star 4
(merger) investigations. The model exhibits a critical end point (CEP) at TCEP = O(100) MeV and 5
μB CEP = 500 . . . 700 MeV with emerging first-order phase transition (FOPT) curve which extends 6
to large values of μB without approaching the μB axis. We consider the impact and peculiarities of 7
the related phase structure on the EoS for the employed dilaton potential and dynamical coupling 8
parameterizations. These seem to prevent to design an overall trustable EoS without recourse to 9
hybrid constructions.

The solubility of palladium sulfide (PdS(s)) has been measured in H2S/HS– aqueous solutions across wide ranges of sulfur concentrations (0.5–1.2 molal) and pH (5–8) at temperatures from 50 to 300 °C and pressures from 90 to 600 bar, using a hydrothermal flexible-cell reactor allowing controlled fluid injection and sampling. Combined with thermodynamic modeling and analysis of available literature data, our results demonstrate that palladium tetrahydrosulfide, PdII(HS)42–, is the dominant complex in sulfide-rich moderate-temperature hydrothermal fluids. The equilibrium constants of PdS(s) dissolution reaction, PdS(s) + 3 H2S0(aq) = Pd(HS)42– + 2 H+ (Ks4), generated in this study were described by the function log10Ks4 = (196.4±60.0) – (11384±3567)/T(K) – (71.24±19.52) × log10T(K), valid over the temperature range 25–300 °C and from saturated vapor pressure to 600 bar. These results, combined with recent analogous PtS(s) solubility data, enabled the derivation of a self-consistent set of thermodynamic properties of Pd(HS)42– and Pt(HS)42– in the framework of the HKF model. Solubility predictions of PdS(s) using these properties yield maximum solubility values of 1 ppb Pd, as the tetrahydrosulfide complex, in H2S-bearing hydrothermal fluids (>0.01 m S) at moderate temperatures (50–350 °C) and near-neutral pH (6–7), whereas chloride complexes are predominant at acidic pH (<4). The Pd/Pt atomic ratio in typical H2S-bearing hydrothermal fluids at 300 °C in equilibrium with PdS(s) and PtS(s) varies from >104 at pH <2 to 10–2 at pH>3, corresponding to the change from chloride- to sulfide-dominated speciation for both metals. However, the absolute solubilities of both chloride and sulfide complexes are too small over the whole pH range to significantly contribute to Pd/Pt fractionations observed in hydrothermal environments. Among different factors that may lead to such fractionations, the role of polysulfide sulfur species including trisulfur radical ions should be considered in future studies.

Laser-driven plasma accelerators can produce high-energy, high peak current ion beams by irradiating solid materials with ultra-intense laser pulses. This innovative concept attracts a lot of attention for various multidisciplinary applications as a compact and energy-efficient alternative to conventional accelerators. The maturation of plasma accelerators from complex physics experiments to turnkey particle sources for practical applications necessitates breakthroughs in the generated beam parameters, their robustness and scalability to higher repetition rates and efficiencies.
This thesis investigates viable optimisation strategies for enhancing ion acceleration from thin foil targets in ultra-intense laser-plasma interactions. The influence of the detailed laser pulse parameters on plasma-based ion acceleration has been systematically investigated in a series of experiments carried out on two state-of-the-art high-power laser systems. A central aspect of this work is the establishment and integration of laser diagnostics
and operational techniques to advance control of the interaction conditions for maximum acceleration performance. Meticulous efforts in continuously monitoring and enhancing the temporal intensity contrast of the laser system, enabled to optimise ion acceleration in two different regimes, each offering unique perspectives for applications.
Using the widely established target-normal sheath acceleration (TNSA) scheme and adjusting the temporal shape of the laser pulse accordingly, proton energies up to 70 MeV were reliably obtained over many months of operation. Asymmetric laser pulses, deviating significantly from the standard conditions of an ideally compressed pulse, resulted in the highest particle numbers and an average energy gain ≥ 37 %. This beam quality enhancement is demonstrated across a broad range of parameters, including thickness and material of the target, laser energy and temporal intensity contrast.
To overcome the energy scaling limitations of TNSA, the second part of the thesis focuses on an advanced acceleration scheme occurring in the relativistically induced transparency (RIT) regime. The combination of thin foil targets with precisely matched temporal contrast conditions of the laser enabled a transition of the initially opaque targets to transparency upon main pulse arrival. Laser-driven proton acceleration to a record energy of 150 MeV is experimentally demonstrated using only 22 J of laser energy on target. The low-divergent high-energy component of the accelerated beam is spatially and spectrally well separated from a lower energetic TNSA component. Start-to-end simulations validate these results and elucidate the role of preceding laser light in pre-expanding the target along with the detailed acceleration dynamics during the main pulse interaction. The ultrashort pulse duration of the laser facilitates a rapid succession of multiple known acceleration regimes to cascade efficiently at the onset of RIT, leading to the observed beam parameters and enabling ion acceleration to unprecedented energies. The discussed acceleration scheme was successfully replicated at two different laser facilities and for different temporal contrast levels. The results demonstrate the robustness of this scenario and that the optimum target thickness decreases with improved laser contrast due to reduced pre-expansion. Target transparency was found to identify the best-performance shots within the acquired data sets, making it a suitable feedback parameter for automated laser and target optimisation to enhance stability of plasma
accelerators in the future.
Overall, the obtained results and described optimisation strategies of this thesis may become the guiding step for the further development of laser-driven ion accelerators.

When radionuclides (RN) enter the food chain and are ingested by humans, they pose a potential health risk due to their radio- and chemotoxicity. In order to accurately assess the health risk af-ter oral ingestion and to apply effective decontamination methods, it is essential to understand the processes of (bio)chemistry and speciation of RN at the molecular level. To minimize the health risk, chelating agents, which are usually strong complexants, are used after the accidental incorporation of RN for decorporation, that means to increase RN excretion. To date, however, only the aminopolycarboxylate diethylenetriaminepenta-acetic acid (DTPA) is approved and used commercially, although it is only effective for trivalent actinides. Alternative potential decorporation agents such as the hydroxypyridinone 3,4,3-(LI-1,2-HOPO) (HOPO) are being developed [1], but are not yet ready for commercial use.
We experimentally investigated the speciation of trivalent lanthanides and actinides (Ln(III)/An(III)) as well as hexavalent uranium (U(VI)) in model fluids of the digestive tract in the absence and presence of chelating agents. The artificial biofluids saliva, gastric juice, pan-creatic juice, and bile were synthesized according to the international Unified Bioaccessibility Method (UBM) of the Bioaccessibility Research Group of Europe (BARGE) [2]. As chelating agents we used DTPA and alternative aminocarboxylates like ethylene diamine tetraacetic acid (EDTA) or ethyleneglycol tetraacetic acid (EGTA) [3], as well as some promising new chelators like HOPO [1] and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), which was formerly used as a pharmaceutical. The solutions were spiked with Eu(III) as a non-radioactive analogue for An(III) as well as with the actinides Cm(III) and U(VI). Samples were analyzed multi-spectroscopically, mainly using time-resolved laser-induced luminescence spectroscopy (TRLFS) combined with parallel factor analysis (PARAFAC) as well as nuclear magnetic reso-nance (NMR) spectroscopy.
Speciation studies for Eu(III) and Cm(III) in artificial biofluids resulted in variable coordination spheres with carbonate, phosphate, and also some proteins such as α-amylase or mucin, depend-ing on the composition of the biofluid [4]. The complexation of U(VI) is mainly dominated by carbonate. The influence of the complexants on the speciation of metal ions in the biofluids var-ied. For Eu(III), for example, HOPO displaced bioligands just as strongly as DTPA. HEDP was found to be not suitable for trivalent actinides as it forms insoluble complexes at physiologically relevant pH [5]. For U(VI), both HOPO and HEDP were equally capable of displacing the very strong bioligand carbonate from the coordination sphere.
The results of this work contribute to a better understanding of the effect of decorporation agents after RN incorporation at the molecular level and support making them more effective in the future.

Acknowledgements:

This work is part of the German joint project "Speciation and transfer of radionuclides in the human organism with special consideration of decorporation agents (RADEKOR)" and was funded by the German Federal Ministry of Education and Research (BMBF, grant number 02NUK057A).

[1] R.J. Abergel, P.W. Durbin, B. Kullgren, S.N. Ebbe, J.D. Xu, P.Y. Chang, D.I. Bunin, E.A. Blakely, K.A. Bjornstad, C.J. Rosen, D.K. Shuh, K.N. Raymond, Health Phys. 99, 401-407 (2010).
[2] J. Wragg, M. Cave, H. Taylor, N. Basta, E. Brandon, S. Casteel, C. Gron, A. Oomen, T. van de Wiele, British Geological Survey Open Report OR/07/027, Keyworth, Nottingham, 90 pp (2009).
[3] S. Friedrich, C. Sieber, B. Drobot, S. Tsushima, A. Barkleit, K. Schmeide, T. Stumpf, J. Kretzschmar, Molecules 28, 4881 (2023).
[4] C. Wilke, A. Barkleit, T. Stumpf, A. Ikeda-Ohno, J. Inorg. Biochem. 175, 248-258 (2017).
[5] A. Heller, C. Senwitz, H. Foerstendorf, S. Tsushima, L. Holtmann, B. Drobot, J. Kretzschmar, Molecules 28, 4469 (2023).

Aim: Gaussian filters are commonly used to improve signal to noise ratio (SNR) of PET images but reduce spatial resolution, thus increasing partial volume effects. Edge preserving filters can alleviate this problem. Especially, the bilateral filter (BF) has shown to have very good performance but requires manual tuning of its two parameters (σS, σI) for optimal results. This is time consuming and hampers clinical use. In this work we, therefore, investigated an automatic method for parameter optimization.

Methods: PET-data from 69 patients were included: 18F-FDG(N=33), 18F-LDOPA(N=25), 68Ga-DOTATATE(N=11). All scans were performed with respiratory gating (8 gates), resulting in 552 low SNR PET volumes. Four 3D ROIs were placed in each volume: one within the liver (to assess noise) and three in areas with elevated focal uptake and various SNR levels. Optimal parameters were determined by a grid search in the (σS,σI) plane aiming at parameters that simultaneously leave SUV_max of the focal uptake mostly unaltered while yielding a noise level comparable to that seen in the sum over all gates. BF with the optimized parameters was then applied and images were visually inspected and analyzed regarding ΔSUV_max and ΔNoise differences (BF vs. unfiltered) in the respective ROIs.

Results: In 19/69 datasets our method failed (over-smoothed background or artifacts). For these images the parameters had to be manually tuned. Overall, optimal parameter values varied over a substantial range (mean±sd: σI=(1.4±1.5) SUV and σS=(5.5±1.7) mm) with σI exhibiting a pronounced tracer dependance. ΔSUV_max of the focal uptake ROIs across all datasets was small (-0.5±0.8) while substantial noise reduction was achieved by (-12.3±3.5) percentage points although detailed behaviour differed between tracers.

Conclusions: Our results demonstrate inter-individual and tracer-specific variability of optimal BF parameters and thus underline the need for careful parameter optimization. In 72% of all investigated cases our automated method was able to perform this optimization without any user intervention. More work is needed to further improve the success rate. However, already in its current form our method does notably reduce workload imposed on the user when considering BF for routine use.

Aim: PET images can exhibit high noise levels which adversely affects qualitative and quantitative image evaluation. Especially challenging are respiratory gated studies and dynamic studies. In such cases, Gaussian filtering is routinely used to improve the signal to noise ratio. However, this degrades the spatial resolution and leads to reduced contrast recovery (CR) in small lesions. Edge preserving bilateral filtering is able to overcome this shortcoming but requires careful tuning of its 2 parameters on a per case basis in order to produce optimal results. In this work we evaluate the potential of using a deep neural network for automatic edge preserving image filtering utilizing a training set of manually filtered PET images.

Methods: We collected unfiltered gated PET data from clinical PET/MR (Philips PET/MR) and PET/CT (Siemens PET/CT) systems and interactively optimized bilateral filtering to achieve the best combination of noise reduction and preservation of spatial resolution. The set of pairs of corresponding unfiltered and filtered images was randomly split into training, validation, and testing sets. The convolutional neural network (CNN) was trained to generate the filtered images from the unfiltered ones. The resulting network model was then evaluated using the ROVER software package regarding its denoising and CR performance and also for presence of artifacts.

Results: With the preliminary data available so far, evaluation of the images filtered with CNN yielded results closely resembling these obtained with manually tuned bilateral filtering in terms of noise level and CR. No apparent image artifacts were found.

Conclusions: Our initial results indicate that the CNN-based post-filtering produces images comparable to interactively optimized filtering. However, more thorough analyses with more image data for testing and training is required to draw definite conclusions about reliably of the proposed solution and will be performed in the coming months. Furthermore, integration of the derived network into a new respiratory motion compensation framework is planned.

Aim: Spatial resolution is one of the key parameters for assessment of PET scanner performance. However, spatial resolution is usually determined with point or line sources, not allowing to study the finite object size and contrast effects known to affect iterative image reconstruction results. We present an approach to determine the spatial resolution at finite background for extended objects. The method was applied to preclinical PET/CT systems (Bruker PET/CT Si78, Mediso PET/CT).

Methods: Spatial resolution is assessed as the full width at half maximum (FWHM) of the point spread function (PSF, approximated by a 3D Gaussian). FWHM is determined from a fit of the convolution of the considered object (homogeneous sphere or rod) with the PSF to the reconstructed image data. In this process, the full 3D vicinity of each sphere/rod is evaluated by transforming the data to spherical/cylindrical coordinates relative to the respective object center/axis. F-18 measurements were performed with a cylindrical phantom (diameter 3.5cm) with a cylindrical insert (diameter 1cm). Measurements were performed without background and at contrast ratio 3:1, respectively.

Results: Without background, we obtained FWHM=1.3mm for the Mediso system, but severe Gibbs artefacts are present, indicating a too aggressive resolution recovery approach. The Bruker system achieves FWHM=2.1mm while avoiding any Gibbs artefacts. At 3:1 contrast, resolution of both systems decreases (to FWHM=2.6mm and 3.2mm, respectively) while Gibbs artefacts are not visible for the Mediso system, too.

Conclusions: Our preliminary results show that both investigated systems have a strongly contrast dependent spatial resolution. Optimizations of reconstruction parameters are currently underway with the aim of reducing the adverse effects of Gibbs artefacts on quantification and improving reconstructed image resolution at finite background while avoiding any negative effects on potential quantification.

Background: Residual image noise is substantial in positron emission tomography (PET) and one of the factors limiting lesion detection, quantification, and overall image quality. Thus, improving noise reduction remains of considerable interest. This is especially true for respiratory-gated PET investigations. The only broadly used approach for noise reduction in PET imaging has been the application of low-pass filters, usually Gaussians, which however leads to loss of spatial resolution and increased partial volume effects affecting detectability of small lesions and quantitative data evaluation. The bilateral filter (BF) – a locally adaptive image filter – allows to reduce image noise while preserving well defined object edges but manual optimization of the filter parameters for a given PET scan can be tedious and time-consuming, hampering its clinical use. In this work we have investigated to what extent a suitable deep learning based approach can resolve this issue by tasking a suitable network with reproducing the results of manually adjusted case-specific bilateral filtering.

Methods: Altogether, 69 respiratory-gated clinical PET/CT scans with three different tracers ([¹⁸F]FDG, [¹⁸F]L-DOPA, [⁶⁸Ga]DOTATATE) were used for the present investigation. Prior to data processing, the gated data sets were split, resulting in a total of 552 single-gate image volumes. For each of these image volumes, four 3D ROIs were delineated: one ROI for image noise assessment and three ROIs for focal uptake (e.g. tumor lesions) measurements at different target/background contrast levels. An automated procedure was used to perform a brute force search of the two-dimensional BF parameter space for each data set to identify the “optimal” filter parameters to generate user-approved ground truth input data consisting of pairs of original and optimally BF filtered images. For reproducing the optimal BF filtering, we employed a modified 3D U-Net CNN incorporating residual learning principle. The network training and evaluation was performed using a 5-fold cross-validation scheme. The influence of filtering on lesion SUV quantification and image noise level was assessed by calculating absolute and fractional differences between the CNN, manual BF, or original (STD) data sets in the previously defined ROIs.

Results: The automated procedure used for filter parameter determination chose adequate filter parameters for the majority of the data sets with only 19 patient data sets requiring manual tuning. Evaluation of the focal uptake ROIs revealed that CNN as well as BF based filtering essentially maintain the focal SUVmax values of the unfiltered images with a low mean±SD difference of δSUV_max^CNN,STD =(-3.9±5.2)% and δSUV_max^BF,STD =(-4.4±5.3)%. Regarding relative performance of CNN vs. BF, both methods lead to very similar SUV_max values in the vast majority of cases with an overall average difference of δSUV_max^CNN,BF =(0.5±4.8)%. Evaluation of the noise properties showed that CNN filtering mostly satisfactorily reproduces the noise level and characteristics of BF with δNoise^CNN,BF=(5.6±10.5)%. No significant tracer dependent differences between CNN and BF were observed.

Conclusions: Our results show that a neural network based denoising can reproduce the results of a case by case optimized BF in a fully automated way. Apart from rare cases it led to images of practically identical quality regarding noise level, edge preservation, and signal recovery. We believe such a network might proof especially useful in the context of improved motion correction of respiratory-gated PET studies but could also help to establish BF-equivalent edge-preserving CNN filtering in clinical PET since it obviates time consuming manual BF parameter tuning.

Plasmon polaritons, or plasmons, are coupled oscillations of electrons and electromagnetic fields that can confine the latter into deeply subwavelength scales, enabling novel polaritonic devices. While plasmons have been extensively studied in normal metals or semimetals, they remain largely unexplored in correlated materials. In this paper, we report infrared (IR) nano-imaging of thin flakes of CsV₃Sb₅, a prototypical layered Kagome metal. We observe propagating plasmon waves in real-space with wavelengths tunable by the flake thickness. From their frequency-momentum dispersion, we infer the out-of-plane dielectric function εc that is generally difficult to obtain in conventional far-field optics, and elucidate signatures of electronic correlations when compared to density functional theory (DFT). We propose correlation effects might have switched the real part of εc from negative to positive values over a wide range of middle-IR frequencies, transforming the surface plasmons into hyperbolic bulk plasmons, and have dramatically suppressed their dissipation.

We propose an efficacious approach to derive the generalized parton distributions for the pion and proton, based upon prior knowledge of their respective parton distribution functions (PDFs). Our method leverages on integral representations of the electromagnetic form factors derived from the light-front holographic QCD (LFHQCD) formalism, coupled with PDFs computed from continuum Schwinger functional methods at the hadronic scale. Using these techniques, we calculate gravitational form factors and associated mass distributions for each hadron. Remarkably, our calculations yield results that closely match recent lattice QCD simulations conducted near the physical pion mass. This work not only deepens our understanding of hadronic structure but also highlights the efficacy of the LFHQCD approach in modeling fundamental properties of hadrons.

A recent study by Wang {\it et al.}(arXiv:2308.14871) proposed a novel connection between the nature of the parton distribution function (PDF) and the characteristics of its moments. In this study, we apply these findings to analyze the evolution of the pion valence quark PDF, garnering valuable qualitative insights. Firstly, we validate the non-negativity and continuity of the PDF across a wide range of scales, indicating the logical consistency of our chosen evolution scheme. Subsequently, we examine the unimodality of both the PDF and its transformed counterpart, the xPDF, i.e., the parton distribution function multiplied by the momentum fraction. We observe a smooth evolution of the peak position of the xPDF towards the small-x region with increasing scale, while intriguingly, the PDF undergoes a phase of bimodal competition as the energy scale evolves.

The design of multiphase reaction and separation processes, such as for example catalytic hydrogenations, distillation and absorption processes, extraction processes, wastewater treatment, and many more, require a profound understanding of the multiphase fluid dynamics inside reactors and contactors. As Computational Multiphase Fluid Dynamics is still not fully mature to simulate complex two-phase and three-phase flow with overlaying heat and mass transfer as well as chemical reaction with sufficient accuracy there is a constant need for advanced experimental and measurement techniques; may it be for the provision of operational, design or thermodynamic parameters or for the validation of codes. In this talk we report on three different novel measurement techniques for this purpose. The presentation shall exemplarily demonstrate how advanced measurement and imaging techniques can be used to study opaque two-phase and three-phase flows in lab environment and potentially also in the field. We report on a) the use of ultrafast X-ray tomography and wire-mesh sensors for the study of reactive bubbly flow in a bubble column, b) the application of a large flow profiler in studying two-phase flow on a distillation column tray, and c) a method to obtain gas dispersion parameters in gas-liquid contactors using modulated gas flow.

Flexible polymer composite materials, structured as hydrophobic polymer matrices embedded with soft or stiff conductive fillers, present the opportunity to fine-tune material functionality by balancing electrical, mechanical, and chemical properties. This optimization aims to achieve ideal interfacing with chemical and biological systems, positioning these materials as key components for healthcare device interfaces in diagnostics and therapy. This talk will highlight two types of polymer composite architectures designed for drug delivery and biosensing applications.
In the first part, I will discuss composite hydrogel reservoirs for controlled cationic drug delivery. These composite hydrogels exhibit a unique microstructure: a hydrophobic polymer matrix embedded with soft ionically conductive microgels. This structure is achieved through a fabrication process involving irradiation-induced polymerization followed by liquid phase inversion. The reservoir architecture imposes mechanical constraints on hydrogel swelling, serving as a passive, rate-limiting barrier for diffusion-controlled drug release. Additionally, it allows for external tuning of the delivery rate using electrical signals. The kinetics of cationic drug release from these reservoirs, governed by ion exchange and modulated by electrical excitation, can be described using the concept of the apparent diffusion coefficient. This coefficient can be engineered during fabrication to permit release periods ranging from hours to weeks.
The second part of the talk will explore innovative flexible polymer composite electrodes suitable for constructing fully degradable impedimetric biosensors. These electrodes feature a porous hydrophobic polymer matrix hosting dispersed metallic microparticles. By combining a gradually degrading polymer matrix with metallic particles, we achieve passive corrosion control while maintaining reliable electro-mechanical properties throughout extended degradation periods. Electrode fabrication begins with a viscous ink, applied either via doctor blade coating to form free-standing films or through stencil printing to create electrode patterns directly on substrates. The resulting electrodes maintain a stable impedance profile, resembling an ideal resistor across a broad frequency range, even after hundreds of bending cycles, underscoring their suitability for flexible impedimetric sensors. Our printed electrodes have proven effective as measurement interfaces for monitoring resistance during short-term degradation processes. Furthermore, we demonstrated a strategy for creating fully degradable impedimetric sensors using free-standing electrode films, enabling enzymatic degradation-mediated biosensing relevant to healthcare monitoring applications.
Flexible and conductive polymer composites with tailored architectures are versatile materials that hold great promise for healthcare technologies, aiming to enable more effective diagnostics and therapy in the future.

Electronic biosensors have found numerous applications in point-of-care (POC) diagnostics thanks to their affordability and facile integration into portable devices, enabling rapid digital display of measured data. However, this class of biosensors still did not reach the stability and reliability required for demanding healthcare applications, such as the diagnostics of complex diseases or therapy monitoring, where multiple biomarkers need to be measured simultaneously with high accuracy and sensitivity. In these application scenarios, multiplexing represents a promising practical solution enabling simultaneous and reproducible measurements at many sensing points, as well as robust statistics. Extended gate (EG) field-effect transistor (FET) biosensor systems are excellent candidates for multiplexed sensing of various physiologically relevant (bio)chemical analytes, from ions to biomolecules. The FET transducer endows the system with exceptional sensitivity and straightforward interfacing with readout electronics, while the physical separation of the gate electrode from the transducer facilitates the integration of multiple individually tailored sensing points into the compact, disposable, and cost-effective sensing interface with versatile architectures [1]. We have demonstrated multiplexed, portable, and standalone EG-FET biosensing platforms combining the optimized design of conventional electronics based on off-the-shelf components and different innovative assay strategies, thereby achieving remarkable detection limits for biomolecules, improved by several orders of magnitude compared to clinical gold standard ELISA assays. Using gold nanoparticle analyte labels as nanoantennae, we realized a highly sensitive POC immunosensor [2]. Moving beyond the traditional POC diagnostics applications, we implemented an indirect assay methodology enabling the detection of target molecules relevant for monitoring cancer immunotherapy [3]. Our EG-FET platforms offer a great opportunity for advanced digitalized healthcare screening and monitoring by quickly providing more comprehensive information to clinicians. They can be easily upgraded to support data connectivity and effective incorporation of artificial intelligence. We envision EG-FET biosensing platforms as important components of future digital health ecosystems.

References
[1] Ž. Janićijević, T.-A. Nguyen-Le, and L. Baraban, ‘Extended-gate field-effect transistor chemo- and biosensors: State of the art and perspectives’, Next Nanotechnology, vol. 3–4, p. 100025, Sep. 2023, doi: 10.1016/j.nxnano.2023.100025.
[2] Ž. Janićijević, T.-A. Nguyen-Le et al., ‘Multiplexed extended gate field-effect transistor biosensor with gold nanoantennae as signal amplifiers’, Biosensors and Bioelectronics, vol. 241, p. 115701, Dec. 2023, doi: 10.1016/j.bios.2023.115701.
[3] T.-A. Nguyen-Le et al. ‘Towards precision immunotherapy: FET biosensors for immunotherapeutic drug monitoring in UniCAR T-cell therapy’, Manuscript in preparation

Objectives: To develop a gadolinium-free MRI-based diagnosis prediction decision tree (DPDT) for adult-type diffuse gliomas and to assess the added value of a gadolinium-based contrast agent (GBCA).
Materials and Methods: This study included preoperative grade 2-4 adult-type diffuse gliomas (World Health Organization 2021) scanned from January 2010 to 2021. The DPDT, incorporating eleven GBCA-free MRI features, was developed using 18% of the dataset based on consensus readings. Diagnosis predictions involved grade (grade 2 vs. grade 3/4) and molecular status (IDH and 1p/19q). GBCA-free diagnosis was predicted using DPDT, while GBCA-enhanced diagnosis included post-contrast images. The accuracy of these predictions was assessed by three raters with varying experience levels in neuroradiology using the test dataset. Agreement analyses were applied to evaluate the prediction performance/reproducibility.
Results: The test dataset included 303 patients (age (SD): 56.7 (14.2) years, female/male: 114/189, low-grade/high-grade: 54/249, IDH-mutant/wildtype: 82/221, 1p/19q-codeleted/intact: 34/269). Per-rater GBCA-free predictions achieved ≥0.85 (95%-CI: 0.80-0.88) overall accuracy for grade and ≥0.75 (95%-CI: 0.70-0.80) for molecular status, while GBCA-enhanced predictions reached ≥0.87 (95%-CI: 0.82-0.90) and ≥0.77 (95%-CI: 0.71-0.81), respectively. No overall accuracy difference was observed between GBCA-free and GBCA-enhanced predictions. Group inter-rater agreement was moderate for GBCA-free (0.56 (95%-CI: 0.46-0.66)) and substantial for GBCA-enhanced grade prediction (0.68 (95%-CI: 0.58-0.78), p = 0.008), while substantial for both GBCA-free (0.75 (95%-CI: 0.69-0.80) and GBCA-enhanced (0.77 (95%-CI: 0.71-0.82), p = 0.51) molecular status prediction.
Conclusion: The proposed GBCA-free diagnosis prediction decision tree performed well, with GBCA-enhanced images adding little value to the preoperative diagnostic accuracy of adult-type diffuse gliomas.

Long-wavelength free-electrons lasers are unique sources of intense, narrowband THz radiation. I will discuss here time-resolved experiments, where intense THz radiation strongly drives and excites charge carriers in two different types of nanomaterials.
In the first experiment a single GaAs/InGaAs core-shell nanowire with a strained GaAs core and a highly doped InGaAs shell is excited with 12-THz radiation near the tip of a Neaspec scattering scanning near-field microscope (s-SNOM). Subsequently the spectrally resolved mid-infrared response (20-60 THz) is probed using a difference-frequency mixing source. Resulting from this intraband pumping we observe a red shift of the nanowire plasma resonance both in amplitude and phase spectra, which is ascribed to a heating of the electron distribution in the nonparabolic band and to electron transfer into the side valleys, resulting in an increase of the average effective mass.
In the second experiment we excite a single 2D layer of MoSe2 with THz radiation of photon energy in the vicinity of the trion binding energy (here 26 meV). A trion is an exciton that binds a second electron; it is known, even from the hydrogen atom, that its binding energy is roughly an order of magnitude smaller than the exciton binding energy. Subsequently the time-resolved photoluminescence is monitored to observe exciton and trion populations for different excitation photon energies. We clearly identify the resonant ionization of the trion and its conversion to an exciton.

Acoustic focusing of particle flow in microfluidics has been shown to be an efficient tool for particle separation for various chemical and biomedical applications. The mechanism behind the method is the selective effect of the acoustic radiation force on distinct particles. In this way, they can be selectively focused and separated. The technique can also be applied under stationary conditions, i.e., in the absence of fluid flows. In this study, the manipulation of self-propelled particles, such as Janus particles, in an acoustofluidic setup was investigated. In experiments with self-propelled Janus particles and passive beads, we explored the interplay between self-propulsion and the acoustic radiation force. Our results demonstrated unusual and potentially useful effects such as selective trapping, escape, and assisted escape in binary mixtures of active and passive particles. We also analyzed various aspects related to the behavior of Janus particles in acoustic traps in the presence and absence of flows.

The talk gives a short overview about the combination of flash lamp annealing and roll-to-roll applications including the application fields of inkjet printing with nanoparticle inks, transparent conduction oxides, and energy materials.

METABOLATOR is a web application for automated analysis of microcalorimetric metabolic data using Monod's equation. The software was developed in collaboration between the Institute of Resource Ecology and the Department of Information Services and Computing at Helmholtz-Zentrum Dresden - Rossendorf (HZDR), and is now offered as a web service for the community. In addition to publishing the software under an open source license, we made the service, which is hosted on HZDR infrastructure, citable by registering its metadata with DataCite and minting a dedicated Digital Object Identifier (DOI). In this talk, we will present the results of our collaboration from the point of view of a Research Software Engineer (RSE). We will introduce the METABOLATOR software, and discuss its development from initial trials into an installable package and web service. Moreover, we will debate the importance of persistent identifiers (PIDs) for reproducible, citable, and overall FAIR data analysis workflows.

We reveal and analyze an efficient magnetic dynamo action due to precession-driven hydrodynamic turbulence in the local model of a precessional flow, focusing on the kinematic stage of this dynamo. The growth rate of the magnetic field monotonically increases with the Poincaré number Po, characterizing precession strength, and the magnetic Prandtl number Pm, equal to the ratio of viscosity to resistivity, for the considered ranges of these parameters. The critical Po for the dynamo onset decreases with increasing Pm. To understand the scale-by-scale evolution (growth) of the precession dynamo and its driving processes, we perform spectral analysis by calculating the spectra of magnetic energy and of different terms in the induction equation in Fourier space. To this end, we decompose the velocity field of precession-driven turbulence into two-dimensional (2D) vortical and three-dimensional (3D) inertial wave modes. It is shown that the dynamo operates across a broad range of scales and exhibits a remarkable transition from a primarily vortex-driven regime at lower Po to a more complex regime at higher Po where it is driven jointly by vortices, inertial waves, and the shear of the background precessional flow. Vortices and shear drive the dynamo mostly at large scales comparable to the flow system size, and at intermediate scales, while at smaller scales it is mainly driven by inertial waves. This study can be important not only for understanding the magnetic dynamo action in precession-driven flows, but also in a general context of flows where vortices emerge and govern the flow dynamics and evolution.

The former mining activity of U ores in Saxony and Thuringia (Germany) has led to the generation of U contaminated areas. Nowadays, conventional remediation methodologies are not able to remove soluble U entirely. Microorganisms offer an environmental friendly water remediation strategy for U through bioreduction or biomineralization. The present study describes the biostimulation of the native U reducing microbial community in a U contaminated mine water as an efficient and eco-friendly strategy for in situ bioremediation to prospectively support or outperform chemical water treatments. In our study, a multidisciplinary approach of analytical and spectroscopical methods were used. The microbial community was characterized by 16S and ITS1 rRNA gene analyses, showing a relative abundance of native microbial groups with the ability to alter the speciation and redox state of soluble U. A set of anerobic microcosms, supplemented with glycerol (10mM) as electron donor to stimulate U reducing bacteria, were designed as basis of an in situ bioremediation strategy for uranium contaminated waters. The black precipitate formed at the bottom of the microcosm was analyzed by High Energy Resolution Fluorescence Detected Near-edge X-ray absorption fine structure (HERFD-XANES) and Extended X-ray absorption fine structure (EXAFS). The results obtained revealed that microbial cycling processes have a significant impact on the complete enzymatic reduction of soluble U(VI) to U(IV) and U(V) by the addition of an electron donor in low U concentration contaminated mine water.

Neutron irradiation causes embrittlement of reactor pressure vessel (RPV) steels. Post-irradiation annealing is capable of partly or fully restoring the unembrittled condition. While annealing at high temperatures (e.g. 475 °C) was successfully applied to extend the lifetime of operating VVER-440 reactors, the benefit of annealing at lower temperatures (e.g. 343 °C – the maximum to which the primary cooling water can be heated) is a matter of debate. In this study, neutron-irradiated VVER-440 RPV base metal and weld were exposed to isothermal annealing at 343 °C up to 2000 hours. Given the limited amount of material, the degree of recovery was estimated in terms of Vickers hardness, the ductile-brittle transition temperature derived from small punch tests, and the master curve reference temperature derived from fracture mechanics tests of subsized samples. For the base metal, small-angle neutron scattering was applied to underpin the findings at the nm-scale. We have found significant partial recovery in both materials after annealing for 300 hours or longer. The variations of the degree of recovery are critically discussed and put into the context of wet annealing.

Density functional theory based positron lifetime (PL) calculations for cation and oxygen monovacancies in a range of oxides – hematite, magnetite, hercynite, and alumina – have been conducted to compare the impact of defect chemistry and crystal structure on the predicted lifetimes. The role of defect charge state has also been examined. A comparison across the same type of crystalline structure but different composition shows that oxygen vacancies only induce a slight increase in the positron-electron overlap and thus barely modify the PL as compared to the bulk. A much more substantial increase of PL is observed for cation monovacancies, regardless of crystal structure or the elemental nature of the vacancy, which we ascribe to an enhanced localization of charge density around the vacant site. The structural and compositional richness of the oxide leads to longer defect PLs, with defected hercynite exhibiting the longest PLs. The charge state of cation monovacancies modifies only by a small percentage the positron localization, relegating to secondary importance the metal defect’s oxidation state in modifying the lifetime of positrons within vacancy traps.

The most effective anticancer drugs currently entail substantial and formidable side effects, and resistance of tumors to chemotherapeutic agents is a further challenge. Thus, the search for new anticancer drugs as well as novel therapeutic methods is still extremely important. Non-steroidal anti-inflammatory drugs (NSAIDs) can inhibit COX (cyclooxygenase), overexpressed in some tumors. Carboranes are emerging as promising pharmacophores. We have therefore combined both moieties in a single molecule to design drugs with a dual mode of action and enhanced effectiveness. The NSAIDs ibuprofen, flurbiprofen, and fenoprofen were connected with 1,2-dicarba-closo-dodecaborane(12) via methylene, ethylene or propylene spacers. Three sets of carborane-NSAID conjugates were synthesized and analyzed through multinuclear (1H, 11B, and 13C) NMR spectroscopy. Conjugates with methylene spacers exhibited the most potent COX inhibition potential, particularly conjugates with flurbiprofen and fenoprofen, displaying higher selectivity towards COX-1. Furthermore, conjugates with methylene and ethylene spacers were more efficient in suppressing the growth of human cancer cell lines than their propylene counterparts. The carborane-flurbiprofen conjugate with an ethylene spacer was the most efficient and selective toward the COX-2-negative cell line HCT116. Its mode of action was basically cytostatic with minor contribution of apoptotic cell death and dominance of cells trapped in the division process.

Industrial multiphase flows are typically characterized by coexisting morphologies. Modern simulation methods are well established for dispersed (e.g., Euler-Euler) or resolved (e.g., Volume-of-Fluid) interfacial structures. A simulation method that requires less knowledge about the flow in advance would be desirable and should allow describing both types of interfacial structures – resolved and dispersed – in a single computational domain. Such methods that combine interface-resolving and non-resolving approaches are called hybrid models. A morphology adaptive multifield two-fluid model, named MultiMorph Model, is proposed, which is able to handle dispersed and resolved interfacial structures coexisting in the computational domain with the same set of equations. For large interfacial structures an interfacial drag formulation is used to describe them in a volume-of-fluid-like manner. For the dispersed structures, the baseline model developed at Helmholtz-Zentrum Dresden - Rossendorf e.V. (HZDR) is applied. The functionality of the framework is demonstrated by several test cases, including a single rising gas bubble in a stagnant water column. Recent developments focus on the transition region, where bubbles are over- or under-resolved for Euler-Euler or for Volume-of-Fluid, respectively. The contribution will focus on an overview about the fundamentals of the MultiMorph Model and recent simulation results for a plunging jet, a stratified counter-current air-water flow and a column tray of a distillation column.

The variable energy availability in the future energy system requires a certain flexibility of energy consumption by energy-intensive industrial processes. The raw materials industry traditionally has high energy demands and low flexibility. This contribution is concerned with the flexibility potential of the copper recycling industry. The current study utilized FactSage and HSC Chemistry software to simulate secondary copper production and OpenLCA, to quantify the environmental impacts of using various flexibility options, such as change in throughput, temporary shutdown of unit operations, and temporarily switching to hydrogen as an alternative energy source.

Background and Aims
As a novel solution to range uncertainties in proton therapy, the NOVO (Next generation imaging for real-time dose verification enabling adaptive proton therapy) project has recently been launched as a European project spanning an interdisciplinary partnership of eight different institutions across four different European countries with funding from Horizon Europe EIC Pathfinder. The overall aim is the construction of a proof-of-concept gamma-ray and fast neutron imaging system that will enable real-time range-shift monitoring. In this contribution, we present some of the results achieved so far by the NOVO Consortium on experimental detector characteristics, range shift detection capabilities via Monte Carlo (MC) simulations and multivariate modelling.

Methods
The NOVO Compact Detector Array (NOVCoDA) will consist of densely stacked, optically segmented, bar-shaped organic scintillators with light read-out at both ends. Experiments have been performed at the nELBE facility in Dresden, Germany for detailed characterization of a novel organic glass scintillator (OGS) material considered for the NOVCoDA detector elements. In addition, preliminary MC type radiation transport simulations of the NOVCoDA have been performed with the aim of determining range shift detection limits for a future full-scale prototype (total volume of 30 x 20 x 20 cm³).

Results
The OGS samples exhibited excellent energy resolution (below 10 %), time resolution (500 ps), position resolution of nearly 10 mm as well as excellent particle discrimination at approximately 0.35 MeVee. Preliminary MC models incorporating detector resolution have revealed range shift detection limits of around 1 mm at clinically relevant proton beam intensities with improved sensitivities when selecting multiple features from the reconstructed gamma-ray and fast neutron distributions.

Conclusions
We have so far obtained promising results both from the perspective of detector characteristics and the range shift detection limits obtained through computational models of a full-scale NOVCoDA device and the commissioning of a NOVCoDA demonstrator prototype is in progress.

Ultraviolet irradiation can effectively inactivate airborne microorganisms. In this context, a stochastic model based on photochemical inactivation is here presented to simulate the inactivation of microorganisms transported in both laminar and turbulent flows. The model, inspired from radiological and nuclear disciplines, introduces an inactivation probability, i.e. the probability that a single photon inactivates one microorganism. This model, here referred to as Monte Carlo photonic model, is highly compatible with computational fluid dynamics and tracks the trajectory and fate of every airborne microorganism, as it moves through an ultraviolet irradiation field. The model, validated against literature data, is a solid alternative to the classical Eulerian model relying on a susceptibility constant. The model will find application in the design of UV air purifiers and in scenarios where photochemical inactivation takes place.

The folded structure and stability of proteins emanates from their interaction with the water solvent. Water at the protein surface is strongly impacted, resulting in a region with a perturbed hydrogen bonding network. This region, the solvation shell, has distinct properties from that of bulk water, including retarded dynamics and fewer hydrogen bonds. Changes in the structure and dynamics of solvation water can be both perturbed and reported on by Terahertz radiation. Yet, some fundamental properties of solvation water, such as energy transfer within the hydrogen bonding network, remain largely unexplored.
Here, we utilize the TELBE free electron laser source to investigate the nonlinear transmission of lysozyme protein solutions. Z-scan experiments were performed at 0.5 THz, revealing a large nonlinear transmission of water. The nonlinear transmission of lysozyme solutions had a concentration dependent effect, showing that the amount of available water has a role. For the largest protein concentration measured, an inversion in the sign of the nonlinear transmission was observed. These results indicate that the nonlinear properties of protein solutions depend on the fraction of bulk and solvation water, and suggest that the mechanism of energy transfer changes at a threshold value. This work has implications for the study of nonlinear properties in biological systems.

Biomolecular condensates are membrane-less organelles formed via liquid-liquid phase separation of intrinsically disordered proteins. Here, THz spectroscopy is utilized to reveal the structure and dynamics of hydration water in these liquid-like protein environments.

Investigations on how the froth height is influencing the flotation of ultrafine particles using the newly developed separation apparatus MultiDimFlot

The work presents morphology studies of hematite synthesized based on waste iron(II) sulfate.
As a model raw material, long term stored waste iron sulfate from the production of titanium
dioxide from Grupa Azoty Zakłady Chemiczne “POLICE” S.A (Poland) was used.
Until now, several technologies for iron red synthesis have been developed. However, none of
them use long term stored waste iron sulfate, nor microwave-based reaction, which was used in
this study. This method allows the synthesis of iron red at 165°C at a pressure of 20 bar. The
study of the morphology of functional materials is essential from potential applications point of
view. Learning about the surface morphology of iron pigments synthesized based on waste makes
it possible to improve materials quality by modifying them.
The work investigated the influence of factors such as the type of oxidation and precipitation
agents and pH on pigment morphology. The obtained pigments were tested by instrumental
analytical methods, e.g. X-ray Diffraction and BET surface area analysis. The pigments were
analyzed for color and oil number. Texture of pigments was analyzed by Focused Ion Beam
(FIB) method and compared to results of particle size distribution obtained by Dynamic Light
Scattering (DLS) method.
The results of this research show a significant change in the physicochemical properties of
obtained pigments depending on the conditions of synthesis. Laboratory pigments have been
found to be different from commercial pigments. The pigments obtained are characterized by
high purity, low oil number (<35 g/100g) and average agglomeration. During previous studies, an
almost idiomorphic cubic shape of iron red particles was discovered. That shape is also presented
in this work. The difference in properties speaks in favor of synthesized materials.

Microwave-based reactions have gained traction in recent years due to their ability to enhance reaction rates and yield while reducing energy consumption. Also, according to the conception of ‘waste to materials’, various waste feeds are intensively sought to be tested. The experimental setup of this study involved varying pH levels, oxidation agents, and precipitation agents to optimize the synthesis process of iron red based on waste iron sulfate. The selection of oxidation and precipitation agents was found to significantly influence the pigment synthesis process. Various oxidizing agents, including hydrogen peroxide and atmospheric air, were evaluated for their effectiveness in promoting the oxidation of ferrous ions to ferric ions, essential for pigment formation. Additionally, different precipitation agents such as sodium hydroxide and ammonia solution were assessed for their ability to precipitate iron hydroxides and facilitate pigment particle formation. The characterization of synthesized pigments revealed promising results in terms of quality and color properties. Helium Ion Microscopy (HIM) analysis confirmed the formation of well-defined pigment particles with controlled morphology. X-ray diffraction (XRD) studies provided insights into the crystalline structure of the pigments, indicating the presence of characteristic iron oxide phases. By improving this technology, waste iron sulfate can be efficiently transformed into valuable iron pigments, offering a sustainable solution for waste management while meeting the growing demand for high-quality pigments.

Martensitic transformations enable various emerging applications like the shape memory effect and elastocaloric applications in NiTi. Increasing the speed of this transformation can shorten the response time for actuation and increase the power density of caloric cooling systems. Up to now, research on the speed and possible time limits of the martensitic transformation in NiTi has been limited to milli- and microsecond experiments. The dynamics of the transformation for shorter time scales are therefore unknown. Here, we report the fastest transformations in NiTi so far by heating an epitaxial NiTi film with a ns laser pulse and tracking the martensitic transition with in-situ synchrotron X-ray diffraction. We find that the martensite to austenite transition upon heating can proceed within the 7 ns pulse duration of the laser, but it requires substantial overheating as the rate of the transformation increases with the driving energy. The austenite to martensite transition is slower because cooling proceeds by conductive heat transfer, but with appropriate undercooling, the complete transformation from martensite to austenite and back only takes 200 ns. We compare our results to previous experiments on the Heusler alloy Ni-Mn-Ga and (K,Na)NbO3 and find very similar trends, which reveal that fast martensitic transformations in general follow a universal scaling law.

We prepared two-dimensional concentric lateral heterostructures of the monolayer transition metal dichalcogenides (TMDCs) MoS₂ and TaS₂ by reactive molecular beam epitaxy (MBE) on chemically inert and weakly interacting Au(111). The heterostructures are in a size regime where quantum confinement can be expected. Despite large lattice mismatch a seamless interconnection of the two materials has been achieved, confirming that the semiconducting core is fully enclosed by a metallic border around its circumference. The resulting strain is analyzed on the atomic scale using scanning tunneling microscopy (STM), corroborated by calculations based on empirical potentials and compared to results from finite elements simulations.

Considering the increasing demand for Li-ion batteries, there is a need for sophisticated recycling strategies with both high recovery rates and low costs. Applying optical sensors for automating component detection is a very promising approach because of the non-contact, real-time process monitoring and the potential for complete digitization of mechanical sorting processes. In this work, mm-scale particles from shredded end-of-life Li-ion batteries are investigated by five different reflectance sensors, and a range from the visible to long-wave infrared is covered to determine the ideal detection window for major component identification as relevant input signals to sorting technologies. Based on the characterization, a spectral library including Al, Cu, separator foil, inlay foil, and plastic splinters was created, and the visible to near-infrared range (400–1000 nm) was identified as the most suitable spectral range to reliably discriminate between Al, Cu, and other battery components in the recycling material stream of interest. The evaluation of the different sensor types outlines that only imaging sensors meet the requirements of recycling stream monitoring and can deliver sufficient signal quality for subsequent mechanical sorting controls. Requirements for the setup parameters were discussed leading to the setup recommendation of a fast snapshot camera with a sufficiently high spectral resolution and signal-to-noise ratio.

Our aim is to obtain a process understanding of the interaction between Ln and plants, from the initial exposure and the cellular uptake until the translocation into and aboveground parts.
Therefore, we use hydroponically grown Avena strigosa, a grass cultivated as animal feed in many countries, to investigate the uptake of Eu(III), as analogue for trivalent Ln and the actinides Cm(III) and Am(III), and its
distribution throughout the plant.
Laser spectroscopy, chemical microscopy and data deconvolution by iterative factor analysis were combined with autoradiography, liquid chromatography, biochemical methods and ICP-MS to elucidate Eu(III) bioassociation and translocation behavior and to identify the involved physico-chemical binding forms of the metal in the different plant organs.

Our aim is to gain a molecular process understanding of the interaction between Ln and plants: from initial exposure, uptake and speciation in different parts of the root tissue, translocation via plant sap to deposition in shoots and leaves. Therefore, we used hydroponically grown Avena strigosa, a grass cultivated as animal feed in many countries. A. strigosa was exposed to europium, which serves as inactive analog for trivalent actinides (An) such as curium and americium.

Unser Ziel ist es, ein molekulares Prozessverständnis für die Interaktion zwischen Ln/An und Pflanzen zu gewinnen: von der initialen Exposition über die Aufnahme und Speziation in unterschiedlichen Teilen des Wurzelgewebes, der Translokation über Pflanzensäfte bis hin zur Ablagerung in Spross und Blättern.

The Perdew-Zunger (PZ) self-interaction correction (SIC) is an established tool to correct unphysical behavior in density functional approximations. Yet, PZ-SIC is well-known to sometimes break molecular symmetries. An example of this is the benzene molecule, for which PZ-SIC predicts a symmetry-broken electron density and molecular geometry, since the method does not describe the two possible Kekulé structures on an even footing, leading to local minima [Lehtola et al, J. Chem. Theory Comput. 2016, 12, 3195]. PZ-SIC is often implemented with Fermi-Löwdin orbitals (FLOs), yielding the FLO-SIC method, which likewise has issues with symmetry breaking and local minima [Trepte et al, J. Chem. Phys. 2021, 155, 224109].
In this work, we propose a generalization of PZ-SIC - the ensemble PZ-SIC (E-PZ-SIC) method - which shares the asymptotic computational scaling of PZ-SIC (albeit with an additional prefactor). E-PZ-SIC is straightforwardly applicable to various molecules, merely requiring one to average the self-interaction correction over all possible Kekulé structures, in line with chemical intuition. We showcase the implementation of E-PZ-SIC with FLOs, as the resulting E-FLO-SIC method is easy to realize on top of an existing implementation of FLO-SIC. We show that E-FLO-SIC indeed eliminates symmetry breaking, reproducing a symmetric electron density and molecular geometry for benzene. The ensemble approach suggested herein could also be employed within locally scaled variants of PZ-SIC and their FLO-SIC versions.

While two-dimensional (2D) materials are traditionally derived from bulk layered compounds bonded by weak van der Waals (vdW) forces, 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. To elucidate their structure and properties, electron microscopy and first-principles calculations are indispensable tools.

Contributing to the predictive design of these novel nanoscale compounds, here, we present several dozens of candidates derived from applying data-driven research methodologies
in conjunction with autonomous first-principles calculations [3,4]. We find that the oxidation state of the surface cations of the 2D sheets as well as accounting for strong surface relaxations upon exfoliation are crucial factors determining their stabilization.
The candidates exhibit a wide range of appealing electronic, optical and in particular magnetic properties owing to the (magnetic) cations at the surface of the sheets. Despite of several ferromagnetic candidates, even for the antiferromagnetic representatives, the surface spin polarizations are diverse ranging from moderate to large values modulated in addition by ferromagnetic and antiferromagnetic in-plane coupling [3]. These features can be accessed by experimental techniques such as (spin-polarized) scanning tunnelling microscopy. At the same time, chemical tuning by surface passivation provides a valuable handle to further control the magnetic properties of these novel 2D compounds [5] thus rendering them an attractive platform for fundamental and applied nanoscience.

[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] A. Puthirath Balan et al., Mater. Today 58, 164 (2022).
[3] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[4] T. Barnowsky et al., Adv. Electron. Mater. 9, 2201112 (2023).
[5] T. Barnowsky et al., Nano Lett. in press (2024).

This repository contains data to test, develop and debug MALA and MALA based runscripts. If you plan to do machine-learning tests ("Does this network implementation work? Is this new data loading strategy working?"), this is the right data to test with. It is NOT production level data!

We report on defects dynamics during heat treatment in plastically deformed metallic materials using positron annihilation lifetime spectroscopy carried out on the intense pulsed positron beam. The conducted experiment allowed us to observe the changes in the concentration and sizes of vacancy-like defects observed during in-situ annealing. We monitored heat treatments up to 300 oC in hydrostatic extruded Ti and cavitation peened V-4Cr-4Ti alloy. We were able to track the recovery processes in Ti and redistribution of large voids at the surface of cavitation peened V-4Cr-4Ti alloy. The relaxation time during recovery was about 20 minutes. Performed experiments show that in cold-worked metallic materials significant changes in vacancy clusters concentrations occur at mildly elevated temperatures. The presented results give opportunity to the application of in-situ observation of defects dynamic to similar problems related to thermomechanical processing of metallic materials.

Liquid metal batteries have been introduced as promising option to address the needs for new energy storage technologies. Currently, batteries based on sodium and zinc are under development and a favorable option due to their high theoretical cell potential, readily abundant materials and cost-advantages. Nevertheless, they face the problem of self-discharge, which makes it inevitable to understand fluid dynamics in the whole cell. Motivated by that, several types of fluid mechanic instabilities in Na-Zn liquid metal batteries are identified and discussed here. On one hand they can jeopardize secure operation, but on the other hand can also improve mixing and increase the cell efficiency. In doing so, realistic cell as well as operation parameters are included and dimensionless numbers for identifying critical conditions are presented. The phenomena with highest significance for the discussed batteries are solutal convection, swirling flow, electrocapillary Marangoni convection and droplet formation. Still, many open research questions remain and we aim at motivating researchers to dig deeper into some of these topics to contribute to an improved cell design and performance.