Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The electronic structure of UC (x = 0.9, 1.0, 1.1, 2.0) was studied by means of x-ray absorption spectroscopy (XAS) at the C K edge and measurements in the high energy resolution fluorescence detection (HERFD) mode at the U and edges. The full-relativistic density functional theory calculations taking into account the Coulomb interaction U and spin-orbit coupling (DFT+U+SOC) were also performed for UC and UC. While the U HERFD-XAS spectra of the studied samples reveal little difference, the U HERFD-XAS spectra show certain sensitivity to the varying carbon content in uranium carbides. The observed gradual changes in the U HERFD spectra suggest an increase in the C 2p-U 5f charge transfer, which is supported by the orbital population analysis in the DFT+U+SOC calculations, indicating an increase in the U 5f occupancy in UC as compared to that in UC. On the other hand, the density of states at the Fermi level were found to be significantly lower in UC, thus affecting the thermodynamic properties. Both the x-ray spectroscopic data (in particular, the C K XAS measurements) and results of the DFT+U+SOC calculations indicate the importance of taking into account U and SOC for the description of the electronic structure of actinide carbides.

The ingress of water into an underground nuclear repository, described as a worst-case scenario, can lead to the degradation of cement-based engineered barriers and thus to the release of organic cement additives that can affect radionuclide immobilisation. The additive 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) is one of the most commonly used long-term retarders in cement, and also used as a corrosion inhibitor in reinforced concrete and steel. PBTC
is an organophosphonate ligand with one phosphonate and three carboxyl groups [1]. These functional groups make PBTC an effective dispersant and strong complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+). However, neither the complexation of radionuclides by PBTC nor the influence of PBTC on radionuclide retention in cement phases has been investigated.
Therefore, both the complexation of U(VI) with PBTC in solution (binary system) and the influence of PBTC on the U(VI) retention by cementitious materials (ternary system) were investigated for the first time. The U(VI) complexation studies were performed by different series varying the pH from 2 to 11 and/or the U(VI) to PBTC ratio. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterize the complex structure. Complementary DFT calculations were carried out. The U(VI) speciation in presence of PBTC was determined by UV-Vis and TRLFS spectroscopy. In the case of PBTC excess, soluble complex species are formed up to pH >10, which is relevant for cementitious systems due to degradation processes. For the U(VI) retention studies both calcium (aluminate) silicate hydrate (C-(A-)S-H) phases of different compositions, representing different cement degradation stages, as well as hardened cement paste were applied. TRLFS was applied to characterize the U(VI) binding. The PBTC retention was quantified by 1H and 31P solution NMR.

In a nuclear waste repository, cement-based materials are to be used for waste conditioning and as an engineered barrier. The ingress of water into the nuclear waste repository, described as a worst-case scenario, leads to increased aging and degradation of the concrete. These processes are associated with a leaching of diverse organic substances usually added to the cement to realize the desired physicochemical and mechanical properties of the cement-based materials. The impact of the additives is based on their excellent ability to complex metal ions. Consequently, the complexation behavior of such additives towards radionuclides (RN) and thus their impact on RN mobilization and migration into the environment is essential for a comprehensive risk assessment. One of the additives commonly used for long-term retardation of cement hardening is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).
PBTC is a polyfunctional ligand possessing three carboxyl groups and one phosphonate group, which have been shown to make PBTC a strong complexing agent for various metal ions (e.g. Ca2+, Zn2+, Al3+, Fe3+) [1,2]. However, to date, there are no studies on PBTC interaction with radionuclides. Therefore,
the complexation of PBTC with U(VI) was investigated for the first time, using different spectroscopic methods over a wide pH range (2 through 11) to identify and characterize possible complex species.
U(VI)-PBTC species with solubility as high as 100 mM were observed throughout the entire pH range studied, especially when PBTC is in excess. This allowed the convenient application of structuresensitive methods such as NMR, IR, and Raman spectroscopies. Furthermore, time-resolved laserinduced
fluorescence spectroscopy (TRLFS) and UV-Vis titration studies provided insight into U(VI)–PBTC system’s speciation.

Organophosphonates are used multipurpose in the chemical industry. One of the most commonly used organophosphonates is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).[1] The functional groups of PBTC consist of one phosphonate and three carboxylate groups, which make PBTC not only an effective dispersant, but also a very good complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+).[2,3] Due to these properties, PBTC is used, for example, as an efficient long-term retarder in cement, as a corrosion inhibitor in reinforced concrete and steel, or as a scale inhibitor in water treatment plants or cooling water circulation systems.[4,5] However, this ubiquitous use can also lead to anthropogenic discharge into the environment, where PBTC can complex heavy metals or even radionuclides. Complexation can increase the solubility of metal ions and thus their bioavailability. As a result, there is an increased risk of toxic metal ions being distributed in the environment and thus also being absorbed into the human food chain.
However, to date there have been no studies on the complexation of PBTC with radionuclides. For this reason, the complexation of PBTC with U(VI) in the pH range from 1 to 11 was investigated for the first time using various spectroscopic methods. The studies were performed by different series varying the pH or the U(VI) to PBTC ratio. For the methods used, U(VI) concentrations in the mM range were employed, which was possible due to the very good water solubility of the U(VI)-PBTC complexes. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterise the complex structure. Supporting DFT calculations were carried out. The stability constants of the complex species were determined by UV-Vis spectroscopy. By applying the different spectroscopic methods, it was possible to determine chelation of U(VI) by the phosphonate group and one of the carboxyl groups. Furthermore, by means of factor analysis, the distribution of complex species as well as the complexation constants could be determined for the first time. Therefore, the results of this study make it possible to evaluate the risk of PBTC entering the environment in relation to the radionuclide uranium.

The effective spin-1/2 antiferromagnetic Heisenberg-Ising chain materials, ACo₂V₂O₈, A = Sr, Ba, are a rich source of exotic fundamental phenomena and have been investigated for their model magnetic properties both in zero and nonzero magnetic fields. Here we investigate a new member of the family, namely, PbCo₂V₂O₈. We synthesize powder and single-crystal samples of PbCo₂V₂O₈ and determine its magnetic structure using neutron diffraction. Furthermore, the magnetic field/temperature phase diagrams for a magnetic field applied along the c, a, and [110] crystallographic directions in the tetragonal unit cell are determined via magnetization and heat capacity measurements. A complex series of phases and quantum phase transitions are discovered that strongly depend on both the magnitude and direction of the field. Our results show that PbCo₂V₂O is an effective spin-1/2 antiferromagnetic Heisenberg-Ising chain with properties that are, in general, comparable to those of SrCo₂V₂O₈ and BaCo₂V₂O₈. One interesting departure from the results of these related compounds is, however, the discovery of a new field-induced phase for the field direction H ӏӏ [110].

The rising interest in increased manufacturing maturity of quantum processing units is pushing the development of alternative superconducting materials for semiconductor fab process technology. However, these are often facing CMOS process incompatibility. In contrast to common CMOS materials, such as Al, TiN, and TaN, reports on the superconductivity of other suitable transition-metal nitrides are scarce, despite potential superiority. Here, we demonstrate fully CMOS-compatible fabrication of HfN and ZrN thin films on state-of-the-art 300mm semiconductor process equipment, utilizing reactive DC magnetron sputtering on silicon wafers. Measurement of mechanical stress and surface roughness of the thin films demonstrates process compatibility. We investigated the materials phase and stoichiometry by structural analysis. The HfN and ZrN samples exhibit superconducting phase transitions with critical temperatures up to 5.84 and 7.32 K, critical fields of 1.73 and 6.40 T, and coherence lengths of 14 and 7 nm, respectively. A decrease in the critical temperature with decreasing film thickness indicates mesoscopic behavior due to geometric and grain-size limitations. The results promise a scalable application of HfN and ZrN in quantum computing and related fields.

We investigated the elastic properties of Y_1−xNd_xCo₂Zn₂₀ with localized Nd f electrons and ground-state Kramers doublet. All longitudinal and transverse moduli of NdCo₂Zn₂₀ (x = 1) show an elastic softening below 50 K accompanied by a minimum around 2.5 K. The softening, which is robust to magnetic fields up to 8 T, is not observed for samples with Nd concentrations of x = 0.19, 0.05, and 0. In localized f electron systems, elastic softening from high temperatures is often understood by crystal electric field effects; however, this cannot explain the behavior in NdCo₂Zn₂₀. Our experimental and calculated results reveal that the softening neither is caused by a phonon contribution, a Nd³⁺ single-site effect, nor a magnetic interaction. We conclude that the softening is due to a local-symmetry-sensitive electronic state in NdCo₂Zn₂₀.

Direct studies of the adiabatic temperature change (ΔT_ad) in the Ni₄₇Mn₄₀Sn_12.5Cu_0.5 Heusler alloy in steady magnetic fields up to 8 T by the extraction method and in pulsed magnetic fields up to 50 T were carried out in this paper. The alloy Ni₄₇Mn₄₀Sn_12.5Cu_0.5 demonstrates a magnetostructural phase transition (MSPT) of the first order in the 254–283 K temperature range as well as a second order phase transition near the Curie temperature T_C = 313 K. An inverse magnetocaloric effect (MCE) was found in the region of the MSPT, and it reaches the maximum value ΔT_ad = -12 K in 20 T at the initial temperature T₀ = 275 K. The irreversible part of the MCE reached ΔT_ir = -10 K when the field is completely removed. We consider the dynamics of the MCE in the vicinity of the MSPT and discuss the mechanisms that cause the giant irreversibility of the MCE as well as the possibilities of its application in hybrid cooling systems.

The term Research Software Engineer, or RSE, emerged a little over 10 years ago as a way to represent
individuals working in the research community but focusing on software development. The term has been widely
adopted and there are a number of high-level definitions of what an RSE is. However, the roles of RSEs vary
depending on the institutional context they work in. At one end of the spectrum, RSE roles may look similar to
a traditional research role. At the other extreme, they resemble that of a software engineer in industry. Most
RSE roles inhabit the space between these two extremes. Therefore, providing a straightforward, comprehensive
definition of what an RSE does and what experience, skills and competencies are required to become one is
challenging. In this community paper we define the broad notion of what an RSE is, explore the different types
of work they undertake, and define a list of fundamental competencies as well as values that define the general
profile of an RSE. On this basis, we elaborate on the progression of these skills along different dimensions, looking
at specific types of RSE roles, proposing recommendations for organisations, and giving examples of future
specialisations. An appendix details how existing curricula fit into this framework.

Data are an essential part of every scientific endeavour. An efficient and future oriented research data management is therefore essential in order to ensure long-term availability of the generated data. This in turn ensures the reproducibility of scientific results. In order to facilitate FAIR data management within the Helmholtz community the incubator platform “Helmholtz Metadata Collaboration (HMC)” was established.

HMC develops and provides services, tools and trainings to support and improve FAIR (meta)data management in the Helmholtz Association and aligns these approaches with national and international approaches and initiatives (e.g. RDA, EOSC, NFDI) to ensure compatibility with international research communities.

To achieve this goal, HMC builds its work along three strategic areas: (1) Assessing and monitoring the state of FAIR data across Helmholtz, (2) Facilitating the connectivity of Helmholtz research data, and (3) Transforming (meta)data recommendations into implementations. At the centres, HMC supports research communities and data professionals with six research-field specific hubs: At HZDR HMC is represented locally by a unit dedicated to research field Energy and remotely by a unit for research field Matter. In our poster we will illustrate how research and data professional communities at HZDR can benefit from HMC's services, tools and trainings.

Most underground nuclear waste disposal concepts envisage the extensive use of cementitious materials in the geo-engineered barrier as a buffer and borehole sealing material and to ensure the mechanical stability of disposal systems. In order to assess the radionuclide (RN) retention potential of these barrier materials, it is necessary to study the impact of various repository relevant conditions that will evolve over time, such as changed pH values, increased ionic strength, elevated temperatures, or the release of organic components. The U(VI) retention by calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, forming owing to Al-rich additives in cement formulations, was studied for samples with C/S molar ratios of 0.8, 1.2, and 1.6, representing different alteration stages of concrete, and with increasing A/S molar ratios of 0, 0.06, and 0.18 in each series, with special focus on the presence of organics. The latter thereby comprise gluconate (GLU), 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC), and a mixture of cellulose degradation products (CDP) obtained from dry radiolysis (dose rate 0.6 kGy/h, absorbed dose ~ 1.37 MGy) followed by hydrolysis in artificial cement water (pH > 13, anoxic conditions) provided by project partners within the CORI framework. Complementary analytical techniques were applied to address the different specific aspects of the cement / organics / RN ternary systems. 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD) were applied to determine the bulk structure and composition of the synthesized C-(A-)S-H phases. 13C-, and in case of PBTC also 31P-, MAS NMR measurements aimed at localization and speciation of the organic components involved [1]. 1H and 31P solution NMR of the aqueous phase allowed for quantification of the organics’ fraction removed from solution and hence associated with the solid phase. Retained U(VI) species were identified by time-resolved laser-induced luminescence spectroscopy (TRLFS). Zeta-potential measurements were conducted to study the organics’ influence on the surface charge and, upon changing the order of mixing the individual components of the ternary systems (e.g., C-(A-)S-H phases synthesized in absence or presence of U(VI) and/or organics), along with results from spectroscopies, to derive mechanistic understanding of retention processes as well as surface complex models.

Flash lamp annealing (FLA) is an ultra-short annealing method which excellently meets the requirements of thin film processing and has already been used in microelectronics. Due to the relatively high hole mobility, thin Ge layers are highly interesting as a transistor channel material or generally as a functional layer both in CMOS technology and in the field of low-cost electronics. One possibility to realize ohmic contacts with low contact resistance is the use of metal germanides, especially the stoichiometric NiGe phase.
In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by FLA. The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The electrical measurements focus on the determination of contact resistance by the circular transfer length method (cTLM). The contacts were fabricated by two different approaches, and the influence of different process steps on layer morphology and the uncertainty of the measurement was studied.

In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by flash lamp annealing (FLA). The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The film sheet resistance, the free charge carrier mobility and concentration, and the contact resistance were measured by the four-point-probe method, by Hall effect measurements, and by the circular transfer length method, respectively. Based on this data, the formation process of NiGe contacts during FLA is described, which passes through a stage of Ni-rich phases with high electrical resistivity, before the final stoichiometric NiGe phase is formed.

The application of deep learning (DL) algorithms to Earth observation (EO) in recent years has enabled substantial progress in fields that rely on remotely sensed data. However, given the data scale in EO, creating large datasets with pixel-level annotations by experts is expensive and highly time-consuming. In this context, priors are seen as an attractive way to alleviate the burden of manual labeling when training DL methods for EO. For some applications, those priors are readily available. Motivated by the great success of contrastive-learning methods for self-supervised feature representation learning in many computer-vision tasks, this study proposes an online deep clustering method using crop label proportions as priors to learn a sample-level classifier based on government crop-proportion data for a whole agricultural region. We evaluate the method using two large datasets from two different agricultural regions in Brazil. Extensive experiments demonstrate that the method is robust to different data types [synthetic-aperture radar (SAR) and optical images], reporting higher accuracy values considering the major crop types in the target regions. Thus, it can alleviate the burden of large-scale image annotation in EO applications.

Timely and accurate building damage mapping is essential for supporting disaster response activities. While RS satellite imagery can provide the basis for building damage map generation, detection of building damages by traditional methods is generally challenging. The traditional building damage mapping approaches focus on damage mapping based on bi-temporal pre/post-earthquake dataset extraction information from bi-temporal images, which is difficult. Furthermore, these methods require manual feature engineering for supervised learning models. To tackle the abovementioned limitation of the traditional damage detection frameworks, this research proposes a novel building damage map generation approach based only on post-event RS satellite imagery and advanced deep feature extractor layers. The proposed DL based framework is applied in an end-to-end manner without additional processing. This method can be conducted in five main steps: (1) pre-processing, (2) model training and optimization of model parameters, (3) damage mapping generation, (4) accuracy assessment, and (5) visual explanations of the proposed method’s predictions. The performance of the proposed method is evaluated by two real-world RS datasets that include Haiti-earthquake and Bata-explosion. Results of damage mapping show that the proposed method is highly efficient, yielding an OA of more than 84%, which is superior to other advanced DL-based damage detection methods.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with millions of infections and deaths worldwide and devastating impact on global economy. Up to now, vaccines and monoclonal antibody (mAb) therapies lack to provide a long-lasting protection against rapidly evolving new emerging SARS-CoV-2 variants. Thus, novel therapeutic options are pressingly needed especially for immunocompromised patients and/or patients with high risk for developing a severe coronavirus disease 2019 (COVID-19).
In that regard, we developed a novel immunotherapeutic drug based on the SARS-CoV-2 entry receptor angiotensin-converting enzyme 2 (ACE2). This ACE2 decoy potently binds to the SARS-CoV-2 receptor binding domain (RBD), neutralizes SARS-CoV-2 as well as the Delta and Omicron variant and protects hamsters from a SARS-CoV-2 infection. To additionally use this ACE2 decoy for elimination of virus infected cells, we equipped it with an epitope tag. Thus, it can be applied as adapter molecule in the modular platform technologies UniMAB and UniCAR, which already demonstrated great success in the setting of malignant diseases. As adapter molecule the ACE2 decoy is able to efficiently recruit either universal chimeric antigen receptor (UniCAR) modified T cells or, in combination with an anti-peptide epitope-anti-CD3 bispecific Ab of the UniMAB system, unmodified T cells to efficiently kill SARS-CoV-2 RBD expressing human cells.
Taken together, the ACE2 decoy represents a very promising immunotherapeutic drug for both SARS-CoV-2 variant neutralization and infected cell killing via the UniMAB and UniCAR system and might, therefore, clearly improve the treatment of COVID-19 patients.

The evolution of eruptive vents related to calderas is not fully understood. We focus on a structural, rock-magnetic, and geochemical investigation of a ∼314 Ma rhyolite dyke swarm associated with the late-orogenic Altenberg–Teplice Caldera, Bohemian Massif, eastern Variscan belt. The whole-rock major element, trace element, and Nd–Pb isotope geochemistry along with the published U-Pb zircon geochronology link the extra-caldera dyke swarm with intra-caldera ignimbrites. The magnetic fabrics determined using the anisotropy of magnetic susceptibility are interpreted to record a continuum from magma ascent, emplacement, and eruption during sinistral shearing. The latter evidences an interplay with regional tectonics associated with the activity of crustal-scale shear zones. The sinistral kinematics and strike of the dyke swarm, the elongation of caldera intrusive units, and the kinematics of major caldera faults are consistent with the dextral Riedel shear system, where the dykes correspond to antithetic Ŕ/X-shears. Such a kinematic configuration implies that the maximum and minimum principal stresses were oriented roughly north-south and east-west, respectively. The relation between the stress field with respect to the caldera elongation and orientation is not typical. We suggest that a pre-existing mutually perpendicular set of cross-cutting structural lineaments largely controlled the magma chamber and caldera formation.

The accurate and fast assessment of damaged buildings following a disaster is critical for planning rescue and reconstruction efforts. The damage assessment by the traditional methods is time-consuming and with limited performance. In this article, we propose an end-to-end deep-learning network named building damage detection network-plus (BDD-Net+). The BDD-Net+ is based on a combination of convolution layers and transformer blocks. The proposed framework takes the advantage of the multiscale residual convolution blocks and self-attention layers. The proposed framework consists of four main steps: data preparation, model training, damage map generation and evaluation, and the use of an explainable artificial intelligence (XAI) framework for understanding and interpretation of the operation model. The experimental results include two representative real-world benchmark datasets (i.e., the Haiti earthquake and the Bata explosion). The obtained results illustrate that BDD-Net+ achieves excellent efficacy in comparison with other state-of-the-art methods. Furthermore, the visualization of the results by XAI shows that BDD-Net+ provides more interpretable and explainable results for damage detection than the other studied methods.

Oil spill detection has attracted increasing attention in recent years, since marine oil spill accidents severely affect environments, natural resources, and the lives of coastal inhabitants. Hyperspectral remote sensing images provide rich spectral information which is beneficial for the monitoring of oil spills in complex ocean scenarios. However, most of the existing approaches are based on supervised and semi-supervised frameworks to detect oil spills from hyperspectral images (HSIs), which require a massive amount of effort to annotate a certain number of high-quality training sets. In this study, we make the first attempt to develop an unsupervised oil spill detection method based on isolation forest (iForest) for HSIs. First, a Gaussian statistical model is designed to remove the bands corrupted by severe noise. Then, kernel principal component analysis (KPCA) is employed to reduce the high dimensionality of the HSIs. Next, the probability of each pixel belonging to one of the classes of seawater and oil spills is estimated with the iForest, and a set of pseudolabeled training samples is automatically produced using the clustering algorithm on the detected probability. Finally, an initial detection map can be obtained by performing the support vector machine (SVM) on the dimension-reduced data, and the initial detection result is further optimized with the extended random walker (ERW) model so as to improve the detection accuracy of oil spills. Experiments on hyperspectral oil spill database (HOSD) created by ourselves demonstrate that the proposed method obtains superior detection performance with respect to other state-of-the-art detection approaches. We will make HOSD and our developed library for oil spill detection publicly available at https://github.com/PuhongDuan/HOSD to further promote this research topic.

The Energy Hub of the Helmholtz Metadata Collaboration (HMC) conducted interviews with various stakeholders from the Helmholtz Research Field Energy on the topic of research data management (RDM) in 2022. The intentions were to build and serve a metadata community in the energy research field and to extend the Helmholtz-wide survey conducted by HMC in 2021 Arndt et al., 2022). Besides the deeper insight into the current state of RDM and metadata handling at the Helmholtz sites relevant to the Energy Hub the interviews focused on the related needs and difficulties of researchers and their satisfaction with the current state. Furthermore, we tried to discover already existing workflows and software solutions, to establish contacts and to make HMC better known.

Swelling is the most fundamental property of graphite oxides (GO). Here, a structural study of Brodie graphite oxide (BGO) swelling in a set of long chain 1-alcohols (named C11 to C22 according to the number of carbons) performed using synchrotron radiation X-ray diffraction at elevated temperatures is reported. Even the longest of tested alcohols (C22) is found to intercalate BGO with enormous expansion of the interlayer distance from ≈6Å up to ≈63Å, the highest expansion of GO lattice ever reported. Swelling transitions from low temperature alpha-phase to high temperature beta-phase are found for BGO in all alcohols in the C11–C22 set. The transitions correspond to decrease of inter-layer distance correlating with the length of alcohol molecules, and change in their orientation from perpendicular to GO planes to layered parallel to GO (Type II transitions). These transitions are very different compared to BGO swelling transitions (Type I) found in smaller alcohols and related to insertion/de-insertion of additional layer of alcohol parallel to GO. Analysis of general trends in the whole set of 1-alcohols (C1 to C22) shows that the 1-alcohol chain length defines the type of swelling transition with Type I found for alcohols with C<10 and Type II for C>10.

Ion irradiation can cause burrowing of nanoparticles in substrates, strongly depending on the material properties and irradiation parameters. In this study, it is demonstrated that the sinking process can be accomplished with ion irradiation of cube-shaped Ag nanoparticles on top of silicon; how ion channeling affects the sinking rate; and underline the importance of the amorphous state of the substrate upon ion irradiation. Based on these experimental findings, the sinking process is described as being driven by capillary forces enabled by ion-induced plastic flow of the substrate.

Vorstellung der FORKA-Projekte EMPRADO und WERREBA

To help with the decommissioning of the unit 2 of the Greifswald NPP, this study aims at determining the activities of 3H, 14C, 60Co, 152Eu and 154Eu in the concrete to estimate the maximal activity in the entire bioshield.
The study will focus on the activity as a function of depth in the concrete layer, as well as composition of the mineral phases. As the flux of neutrons generated during fission reaction encounters the mineral phases of concrete, the natural elements present in these phases absorb neutrons, which leads to the formation of their radioactive isotopes. Therefore, the elemental composition of each mineral phase in the concrete is important in the activation process, and the concrete being a heterogeneous material, different phases will present different activities.
A precise knowledge of the activities and of the elemental composition of the concrete and its mineral phases helps refining the models to calculate and predict the activities in a long-term scale. The calculations and the experimental results support the sorting of the materials for disposal.
This study will analyze the concrete with three main objectives:

• Activation;
• Chemical composition;
• Structure of the concrete and mineral phases.

We present experimental and simulation data on the oblique angle scattering of heavy Sn ions at 14 keV energy from a Mo surface. The simulations are performed with the binary collision approximation codes TRIM, TRIDYN, TRI3DYN, SDTrimSP, and IMSIL. Additional simulations were performed in the molecular dynamics framework with LAMMPS. Our key finding is the absence of an expected peak in the experimental energy spectrum of backscattered Sn ions associated with the pure single collision regime. In sharp contrast to this, however, all simulation codes we applied do show a prominent single collision signature both in the energy spectrum and in the angular scatter pattern. We discuss the possible origin of this important discrepancy and show in the process, that widely used binary collision approximation codes may contain hidden parameters important to know and to understand.

Si1-x-yGexSny alloys are promising materials for future applications in opto- and
nanoelectronics. These alloys enable effective band gap engineering, a broad
adjustability of the lattice parameter, exhibit much higher carrier mobility than pure Si
and are compatible with CMOS technology. Unfortunately, the equilibrium solid
solubility of Sn in Si1-xGex is less than 1% and pseudomorphic growth of Si1-xyGexSny
on Ge or Si causes in-plane compressive strain in the grown layer, which
degrades the superior properties of the alloys. Therefore, the post-growth strain
engineering using ultrafast non-equilibrium thermal treatments like flash lamp
annealing (FLA) or pulsed laser annealing (PLA) to improve the layer quality is
needed. In this contribution, we discuss the influence of millisecond FLA and
nanosecond PLA on Si1-x-yGexSny alloys and present an efficient way to improve
the layer quality of thin film Si1-x-yGexSny on insulator by PLA. Different Si1-xyGexSny
alloys are directly grown on commercial silicon-on-insulator (SOI) wafers
and treated by FLA or PLA. The material is analysed by micro-Raman spectroscopy,
Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) before
and after the thermal treatments. It is shown that after annealing, the material is
single-crystalline with much better crystallinity than the as-grown layer.

Recently, two methods of habitat selection have gained more relevance in the scientific literature: step selection functions (SSF) and MaxEnt. Despite their similarity these models are hardly ever used in the same context. The former is usually associated with studies based in movement ecology, and the latter is connected to species distribution modeling. Motivated by the difficulty in estimating habitat preferences using SSF, I compared the accuracy of predictions from both models based on movement data. As a case study, I utilized jaguar movement data from 5 countries in Latin American and created SSF and MaxEnt models based on climatic data and land use available from WorldClim and satellite imagery. I compared the accuracy of both types of models using the “Area Under Curve” (AUC) metric, on a separate subset of data. SSF models presented an average AUC of 0.5510 ± 0.0147 in comparison with 0.7544 ± 0.0185 of their MaxEnt equivalents. I believe those differences are partially caused by the convergence difficulties of SSF and conditional logistic regression. Consequently, I recommend the use of MaxEnt in predictive modelling, such as the ones needed in reserve and corridor design.

Fine-grained solid particles from various industrial sources, which would otherwise be discarded, should ideally be processed to valuable products or inert residues. Among others, a) shredder fines from electronics and end-of-life vehicles, and b) flue dusts from non-ferrous metallurgical processes are of timely interest. They contain valuable residuals, such as metals, that can be returned to the industrial cycle instead of being landfilled. This is one aim of the Helmholtz project FINEST in which this work is embedded. In this work, mixing and agglomeration of such particles with a size below 1 mm are investigated for further use in the metallurgical industry. Different particle sizes and densities are considered. The process is observed experimentally using camera imaging technique and µCT. From the µCT images a mixing index is acquired. We present an experimental setup and methods for the aforementioned investigations.

Dynamic compression of iron to Earth-core conditions is one of the few ways to gather important elastic and transport properties needed to uncover key mechanisms surrounding the geodynamo effect. Herein a new machine-learned ab-initio derived molecular-spin dynamics (MSD) methodology with explicit treatment for longitudinal spin-fluctuations is utilized to probe the dynamic phase-diagram of iron. This framework uniquely enables an accurate resolution of the phase-transition kinetics and Earth-core elastic properties, as highlighted by compressional wave velocity and adiabatic bulk moduli measurements. In addition, a unique coupling of MSD with time-dependent density functional theory enables gauging electronic transport properties, critically important for resolving geodynamo dynamics.

Exploitation of microalgal biomass as a valuable resource is hindered by the challenges associated with high downstream
processing costs, including biomass harvesting, drying, and product extraction. Direct utilization of microalgae as a solid fuel
source, soil conditioner, capacitor or adsorbent material raises environmental concerns. Hydrothermal carbonization (HTC)
is a highly efficient and promising technology for microalgal biomass conversion. This comprehensive review provides an indepth
understanding of the HTC reaction mechanisms involved in microalgal hydrochar production, shedding light on the
underlying processes and factors affecting the quality of hydrochar. HTC has the potential to improve fixed carbon content,
thermal stability and nutrient availability in the resulting hydrochar. Furthermore, this review explores the integration of HTC
with anaerobic digestion (AD) to establish a circular bioeconomy, thereby promoting sustainability in energy generation. The
synergistic combination offers a promising approach for the efficient utilization of microalgal biomass, where hydrochar can
serve as a renewable energy source while the aqueous fraction can be utilized as a nutrient-rich feedstock for biogas
production. By highlighting the potential benefits and futuristic directives associated with microalgal biomass valorisation
through HTC, this review aims to contribute to the development of sustainable waste management strategies for recovery of
value-added compounds from microalgae. Ultimately, this review strives to foster the transition towards a more
environmentally friendly and resource-efficient bioeconomy.

Im Vortrag geht es um Resourcen und Rohstoffe, Einteilung, Kritikalität, circular economy, Recycling und Alternativen, sowie als Beispiel um Seltene Erden

The present study aimed to investigate the genesis and characteristics of some of the world-famous agate deposits in the state of Chihuahua, Mexico (Rancho Coyamito, Ojo Laguna, Moctezuma, Huevos del Diablo, Agua Nueva). Geochemical and textural studies of host rocks showed that all the studied deposits are related to the same rock type within the geological unit of Rancho el Agate andesite, a quartz-free latite that shows clear indications of magma mixing. As a result of their large-scale distribution and various differentiation processes, as well as transport separation, different textures and local chemical differences between rocks of different localities can be observed. These differences have also influenced the properties of SiO2 mineralization in the rocks. The mixing of near-surface fluids from rock alterations with magmatic hydrothermal solutions led to the accumulation of various elements in the SiO2 matrix of the agates, which were, on the one hand, mobilized during secondary rock alteration (Fe, U, Ca, K, Al, Si) and, on the other hand, transported with magmatic fluids (Zn, Sb, Si, Zr, Cr). Different generations of chalcedony indicate a multi-stage formation as well as multiple cycles of filling the cavities with fluids. The hydrothermal fluids are presumably related to the residual solutions of a rhyolitic volcanism, which followed the latitic extrusions in the area and probably caused the formation of polymetallic ore deposits in the Chihuahua area. The enrichment of highly immobile elements indicates the involvement of volatile fluids in the agate formation. The vivid colors of the agates are almost exclusively due to various mineral inclusions, which consist mainly of iron compounds.

Sandwich packings represent new separation column internals, with a potential to intensify mass
transfer. They comprise two conventional structured packings with different specific geometrical surface areas.
In this work, the complex fluid dynamics in sandwich packings is modeled using a novel approach based on a onedimensional,
steady momentum balance of the liquid and gas phases. The interactions between the three present
phases (gas, liquid, and solid) are considered by closures incorporated into the momentum balance. The
formulation of these closures is derived from two fluid-dynamic analogies for the film and froth flow patterns.
The adjustable parameters in the closures are regressed for the film flow using dry pressure drop measurements
and liquid hold-up data in trickle flow conditions. For the froth flow, the tuning parameters are fitted to overall
pressure drop measurements and local liquid hold-up data acquired from ultra-fast X-ray tomography (UFXCT).
The model predicts liquid hold-up and pressure drop data with an average relative deviation of 16.4 % and 19 %,
respectively. Compared to previous fluid dynamic models for sandwich packings, the number of adjustable
parameters could be reduced while maintaining comparable accuracy.

In recent years, hierarchical nanostructures have found applications in fields like diagnostics, medicine, nano-optics, and nanoelectronics, especially in challenging applications like the creation of metasurfaces with unique optical properties. One of the promising materials to fabricate such nanostructures has been DNA due to its robust self-assembly properties and plethora of different functionalization schemes. Here, we demonstrate the assembly of a two-dimensional fishnet-type lattice on a silicon substrate using cross-shaped DNA origami as the building block, i.e., tile. The effects of different environmental and structural factors are investigated under liquid atomic force microscopy (AFM) to optimize the lattice assembly. Furthermore, the arm-to-arm binding affinity of the tiles is analyzed, revealing preferential orientations. From the liquid AFM results, we develop a methodology to produce closely-spaced DNA origami lattices on silicon substrate, which allows further nanofabrication process steps, such as metallization. This formed polycrystalline lattice has high surface coverage and is extendable to the wafer scale with an average domain size of about a micrometer. Further studies are needed to increase the domain size toward a single-crystalline large-scale lattice.

The emergence of a spatially-organized population distribution depends on the dynamics of the population and mediators of interaction (activators and inhibitors). Two broad classes of models have been used to investigate when and how self-organization is triggered, namely, reaction-diffusion and spatially nonlocal models. Nevertheless, these models implicitly assume smooth propagation scenarios, neglecting that individuals many times interact by exchanging short and abrupt pulses of the mediating substance. A recently proposed framework advances in the direction of properly accounting for these short-scale fluctuations by applying a coarse-graining procedure on the pulse dynamics. In this paper, we generalize the coarse-graining procedure and apply the extended formalism to new scenarios in which mediators influence individuals' reproductive success or their motility. We show that, in the slow- and fast-mediator limits, pulsed interactions recover, respectively, the reaction-diffusion and nonlocal models, providing a mechanistic connection between them. Furthermore, at each limit, the spatial stability condition is qualitatively different, leading to a timescale-induced transition where spatial patterns emerge as mediator dynamics becomes sufficiently fast.

In this work, the extraction of vanadium (V) ions from an alkaline solution using a commercial quaternary ammonium salt and the production of metal vanadates through precipitation stripping were carried out. The crystallization of copper vanadates from the extracts was performed using a solution containing a copper(II) source in concentrated chloride media as a stripping agent. In an attempt to control growth, a stabilizing polymer (polyvinylpyrrolidone, PVP) was added to the stripping solution. The structural characteristics of the crystallized products, mainly copper pyrovanadate (volborthite, Cu3V2O7(OH)2·(H2O)2) nanoflakes and nanoflowers and the experimental parameter influencing the efficiency of the stripping process were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable three-dimensional structures providing abundant active zones for energy and catalytic applications.

Geochemical and mineralogical investigations of the Lower Permian Kemmlitz rhyolite within the NW-Saxonian Basin
(Germany) and associated lithophysae (high-temperature crystallization domains) as well as agates were carried out to
constrain the genesis and characteristics of these volcanic rocks and the origin of the agate-bearing lithophysae. The
volcanic rocks of rhyolitic composition are dominated by quartz, sanidine, and orthoclase and most likely derive from lava
flows. Agate-bearing lithophysae were exclusively formed in a glassy facies (pitchstone) of the rhyolites, which was
afterwards altered to illite-smectite mixed-layer clays. The results of this study show that agate formation can be related to
the alteration of the volcanic rocks accompanied by the infill of mobilized silica into cavities of lithophysae. Fluid inclusion
studies point to temperatures of agate formation above 150 °C, indicating that the mobilization and accumulation of silica
started already during a late phase of or soon after the volcanic activities. Remarkable high concentrations of B (29 ppm),
Ge (> 18 ppm), and U (> 19 ppm) as well as chondrite-normalized rare earth element (REE) distribution patterns of the
agates with pronounced negative Eu-anomalies, slightly positive Ce-anomalies and enriched heavy rare earth elements
(HREE) indicate interactions of the host rocks and transport of SiO2 with magmatic volatiles (F/Cl, CO2) and heated
meteoric water. Characteristic yellow cathodoluminescence (CL), heterogeneous internal textures as well as high defect
density of micro- and macrocrystalline quartz detected by electron paramagnetic resonance (EPR) spectroscopy point to
crystallization processes via an amorphous silica precursor under non-equilibrium conditions.

At a solid boundary, the structural formation of bubbles is different from that in the bulk of a liquid foam. The presence of a solid boundary imposes additional constraints, resulting in a crystalline arrangement of the bubbles. For dry and monodisperse foam, the Kelvin and Fejes-T ́ oth structure is expected in the vicinity of the wall, while a random ordering should occur in the bulk. In this study, we investigate the transition from a crystalline to a random structure near a vertical wall located in the middle of a flat foam cell. The corresponding layering of the liquid was quantified by measuring the distribution of liquid fraction within the cell using neutron radiography. The amplitude of the liquid fraction distribution and its decay with distance from the solid boundary were correlated with the foam bubble size and polydispersity. Furthermore, by applying forced drainage, we measured the corresponding permeability and wetting front velocity near the vertical wall. We found that the crystalline sorting reduces the permeability and wetting front velocity compared to a randomly packed foam.

The measurement of bubble sizes in aqueous foams based on images of the surface is a typical method used in laboratory and industrial scales. In this article the relationship between the size distribution of the facet areas and the bubble size of wall-touching bubbles is investigated. To achieve this an invasive sampling approach is used for in-situ collection of wall-touching bubbles in dry foams, while the surface is imaged in parallel. Bubble and facet
size distributions are obtained using automated image processing. It is shown that sharp peaks in the bubble size distribution will appear smoother in the facet size distribution. This results in an overestimation of polydispersity by the surface measurements. Furthermore, it is observed that the mean equivalent diameter of the facets is on average 6% smaller than the bubble diameter obtained using the sampling method. An approach proposed by
Wang and Neethling (Colloids Surf. A: Physicochem. Eng. Asp. 33, 73-81 (2009)) gives a good approximation of the relation between facet and bubble size and can be used to reduce potential uncertainties in surface based bubble size measurements.

Although, the wettability is the most prominent separation feature in froth flotation, other particle properties, such as size or morphology also affect the separation process since it includes a number of complex micro processes with specific particle-bubble interactions that occur in the pulp and in the froth phase. A novel separation apparatus is used that combines the advantages of a mechanical flotation cell (high particle-bubble collision rate) with those from a flotation column (fractionating effect of the deep froth). A well-characterised model system of ultrafine particles (< 10 µm), consisting of glass spheres and glass fragments as the floatable fraction and magnetite as the non-floatable fraction is used for the separation tests. Based on image analysis bivariate tromp maps are computed which reveal the combined effect of the particle properties of size and shape on the separation behaviour of ultrafine particles.

In high-energy physics, we want to simulate complex physical processes that require computational resources of the fastest HPC systems in the world. In order to fully use the computational resources, software that is maintainable, performant and extensible is required. To achieve these goals, automated testing is essential.
Modern Julia HEP software is modularized into sub-packages to improve maintainability and extensibility. This creates new challenges for automated testing. Unit tests and integration tests are required. If the code of one package is changed, unit tests ensure that the package is still working, whereas integration tests ensure that in dependent packages no functionality break is caused by the change.
Using the QED.jl [1] project as an example, I will demonstrate how we implemented unit and integration tests for the main QED.jl package and its sub-packages.

[1] https://github.com/QEDjl-project/QED.jl

Zirconium dioxide is a corrosion product of the Zircaloy cladding, which houses the nuclear fuel pellets. It can form solid solutions with uranium as well as fission and activation products. Moreover, ZrO2 and other zirconium bearing crystalline solid phases, such as pyrochlores, are being investigated as potential host matrices for the immobilization of radionuclides present in high-level waste streams. Zirconate pyrochlores are characterized by high chemical durability and radiation resistance. However, upon irradiation, some zirconate pyrochlores undergo a phase transition to the defect fluorite crystal structure, or become amorphous, which could hamper a continued immobilization of radionuclides in the solid matrix. In the current study, the influence of different synthesis methods on the phase purity of Ce/Nd-co-doped zirconates was investigated. Furthermore, phase transformations occurring in zirconate phases as a result of different U/Y-dopant concentrations were studied.
Ce/Nd-co-doped zirconates and U/Y-co-doped zirconates were obtained via coprecipitation. In addition, identical zirconate compositions were synthesized using three different solid-state methods involving manual mixing with a mortar and pestle, mechanical mixing with a ball mill or magnetic mixing in a slurry. PXRD measurements of all solids were done for crystal structure analysis.
For the Ce/Nd-co-doped zirconates synthesized via coprecipitation, rather phase-pure monoclinic, cubic defect fluorite and cubic pyrochlore structures could be obtained. The samples synthesized via solid-state methods were found to contain multiple phases due to insufficient mixing of the educts. Manual mixing led to the most phase-pure ceramics and was therefore chosen for further investigation. It was shown that re-sintering the ceramics as well as longer grinding time resulted in enhanced phase purity. Furthermore, an increase of the Nd-content also correlates with an improved phase purity.
PXRD data of the U-doped zirconates showed a peak-shift towards lower two theta values with increasing U-concentration. At the same dopant concentrations, U/Y-co-doped zirconates showed higher symmetry crystal structures than Ce/Nd-co-doped zirconates. This is caused by the larger ionic radius of U4+ compared to Ce4+ allowing for the stabilization of higher symmetry crystal structures at equal dopant concentrations.

Iron-reducing bacteria perform anaerobic respiration by coupling the oxidation of organic molecules to the reduction of Fe(III)-species via dissimilatory iron reduction. This leads to the formation of ferrous minerals, such as vivianite [Fe(II)₃(PO₄)₂], pyrite (Fe(II)S₂), siderite (Fe(II)CO₃) and jahnsite [(CaMn(II))Fe(II)₂Fe(III)₂(PO₄)₄(OH)₂·(H₂O)₈], which, depending on oxygen exposure and the cultivation nutrients, may oxidize and generate magnetite (Fe(II)Fe(III)₂O₄) and/or hematite (Fe(III)₂O₃). The aforementioned secondary Fe(II)-minerals may promote the reduction of radionuclides such as the β-emitter technetium-99 (⁹⁹Tc).
⁹⁹Tc is a long lived fission product (t(1/2) = 2.13 × 10⁵ years) of ²³⁵U and ²³⁹Pu. It can also originate from the decay chain of ⁹⁹₄₂Mo, (Mo-99 → ₄₃Tc-99m + e⁻, 66 h; ₄₃Tc-99m → ₄₃Tc-99 + γ, 6.02 h). In the environment, Tc is prevalent as Tc(VII) or Tc(IV). Due to the common use of Tc-99m in radiodiagnostics, water contamination through the highly hydrosoluble pertechnetate Tc(VII)O₄⁻ must be considered. Nevertheless, Tc can be immobilized by reducing it to the low-soluble oxide Tc(IV)O₂.
This work aims at unravelling the interactions between pivotal anaerobic bacteria (e.g. the iron reducer Desulfitobacterium sp. G1-2) that can be found in bentonite (a clay potentially used as a barrier material for deep geological repositories) and Tc(VII), to achieve its reduction to Tc(IV) and preserve the environmental safeguard.
The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072).

Bacterial colonization and biofilm formation on abiotic surfaces are initiated by the adhesion of peptides and proteins. Understanding the adhesion of such peptides and proteins at a molecular level thus represents an important step toward controlling and suppressing biofilm formation on technological and medical materials. This study investigates the molecular adhesion of a pilus-derived peptide that facilitates biofilm formation of Pseudomonas aeruginosa, a multidrug-resistant opportunistic pathogen frequently encountered in healthcare settings. Single-molecule force spectroscopy (SMFS) was performed on chemically etched ZnO(112̅0)surfaces to gather insights about peptide adsorption force and its kinetics. Metal-free click chemistry for the fabrication of peptide-terminated SMFS cantilevers was performed on amine-terminated gold cantilevers and verified by X-ray photoelectron spectroscopy (XPS) and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Atomic force microscopy (AFM) and XPS analyses reveal stable topographies and surface chemistries of the substrates that are not affected by SMFS. Rupture events described by the worm-like chain model (WLC) up to 600 pN were detected for the non-polar ZnOsurfaces. The dissociation barrier energy at zero force ΔG(0), the transition state distance xband bound-unbound dissociation rate at zero force koff(0) for the single crystalline substrate indicate that coordination and hydrogen bonds dominate thepeptide/surfaceinteraction.

Technetium (Tc, Ordnungszahl 43) ist das leichteste Element, welches keine stabilen Isotope besitzt. Das Hauptvorkommen von Tc stammt aus anthropogen Quellen, wie abgebrannten Brennstoffen aus Kernkraftwerken, Atomwaffentests, sowie nuklearen Unfällen. Das Radionuklid Tc-99 entsteht hierbei als ein Spaltprodukt mit rund 6% Ausbeute und ist somit im nuklearen Abfall vorhanden, welcher im geologischen Tiefenendlager für 1Mio Jahre gelagert werden soll. Zusätzlich wird Tc-99m als Kontrastmittel in der Medizindiagnostik angewendet, welches zu Tc-99 zerfällt und in das Abwasser gelangt. Aus diesen Gründen besteht die Notwendigkeit, die Interaktion von Tc mit Mineralen zu untersuchen, um Möglichkeiten zur immobilisierung zu finden. Das in Wasser mobile Pertechnetat (Tc(VII)O₄⁻) kann durch Sorption und Reduktion zu schwerlöslichem TcO₂ an Fe(II)-haltigen Mineralen zurückgehalten werden.
In dieser Arbeit wurde die Retention an Vivianit (Fe₃(PO₄)₂·8 H₂O) untersucht. Das türkisfarbene Mineral wurde erfolgreich über eine Präzipitation unter Inertgas synthetisch hergestellt. Mittels XRD und Raman konnte die Übereinstimmung mit Referenzspektren für Vivianit bei dem Gleichwichts-pH-Wert pH 6,7 festgestellt werden. Bei einer Verringerung des pH-Wertes auf pH 5 ist Vivianit weiterhin stabil, während bei einem pH-Wert von pH 12 eine Phasenänderung zu Amakinit (Fe(II)(OH)₂) stattfindet. TcO₄− kann durch suspendiertes Vivianit aus der Lösung bei pH 8 im Verlauf von 20 d entfernt werden, während bei pH 6,5 die Immobilisierung nicht stattfindet. Mit steigender Konzentration an Vivianit in der Lösung steigt auch die Entfernung von TcO₄− bei pH 6,5. Bei pH 8 hingegen sinkt die Entfernung mit größerer Mineralkonzentration bei 3 d Sorptionszeit, wobei nach 10 d Tc in der Lösung nicht mehr detektierbar ist. Vermutet wird die Bildung löslicher Tc-phosphate. Mit steigendem pH-Wert steigt die Immobilisierung von Tc aus der Lösung. Bei niedrigen pH-Werten ist die geringe Sorption auf die hohe Löslichkeit des Minerals und damit auf die kinetisch gehinderte Homoreduktion von Tc(VII) durch gelöstes Fe(II) zurückzuführen. Die Untersuchung der Oberfläche mit XPS deutet auf eine vollständige Reduktion von Tc(VII) zu Tc(IV) hin. Die weiterhin hohe Löslichkeit des Tc untermauert die Theorie der Tc-phosphatverbindungen.
Ein Anstieg an oxidischen Verbindungen, welche auf TcO₂ hindeuten, wurden einzig bei pH 12 detektiert. Die Reoxidationsexperimente in dieser Arbeit haben eine geringe Remobilisierung von Technetium unter oxidierenden Bedingungen nach 30 d gezeigt. Im Gegenteil konnte sogar eine Steigerung der Immobilisierung bei niedrigen pH-Werten festgestellt werden.

Dissimilatory iron reduction is an anaerobic respiratory pathway, wherein ferric (Fe³) reducers couple the oxidation of organic acids, sugars and aromatic hydrocarbons to the reduction of Fe³-species [1]. This may lead to the formation of minerals such as magnetite (Fe²Fe³₂O₄) and siderite (Fe²CO₃) [2], which, in turn, can mediate the reduction of soluble pollutants as pertechnetate (Tc⁷O₄⁻) to insoluble oxides (Tc⁴O₂) [3].
The genus Desulfitobacterium contains obligate anaerobic bacteria that are capable of utilizing a wide range of electron acceptors, including nitrite, sulfite, metals, humic acids and halogenated organic compounds [4].
In this work, the Fe³ reduction of a Desulfitobacterium species was examined. The microorganism has been isolated from bentonite, which is potentially used as geotechnical barrier in deep geological repositories for radioactive waste [5].
The cultivation conditions included DSMZ 579 medium with Na-acetate as electron donor to reduce Fe³ citrate [6]. During cultivation, the formation of white precipitates was observed. The phases were collected both under aerobic and anaerobic conditions and repeatedly investigated by using Raman microscopy and powder X-ray diffraction (pXRD). It was noticed that the phases turned immediately to blue-greenish overnight under oxic conditions. Both Raman spectra and pXRD diffractograms can be attributed to vivianite (Fe²₃(PO₄)₂). Moreover, Raman spectra revealed the possible presence of pyrite (Fe²S₂), siderite, magnetite and hematite (Fe³₂O₃). These results suggest the ability of the bacterium of forming different Fe²-minerals. Notwithstanding, both methods indicate the change of the chemistry of the precipitates according to environmental factors. The Fe²-minerals formation by this microorganism depending on Fe³-compounds and background electrolytes is currently ongoing. The biogenic ferrous minerals will be studied regarding the reduction of Tc⁷O₄⁻.
The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072).

Tc-99 is a fission product of U-235 and Pu-239 with a long half-live (2.14∙10⁵ years). Under oxidizing conditions, Tc main species (Tc(VII)O₄⁻) exhibits a high solubility and hardly interacts with minerals. In contrast, under reducing conditions, Tc(IV) presents a more limited mobility, either because Tc(IV) interacts with minerals or Tc(IV)O₂ is formed [1]. However, the formation of Tc(IV)O₂ is not sufficient to ensure the immobilization of Tc, since when it is in contact with O₂, the reoxidation of Tc(IV) to Tc(VII) would be thermodynamically favorable. In contrast, the formation of Tc(IV) polysulfide species (such as TcSx or Tc₂S7) could inhibit Tc oxidation under oxidizing conditions [2]. Therefore, S(-II) seems a promising candidate to immobilize Tc. Sulfide would be present in the nuclear waste repository due to the addition of fly ash in the concrete, as well as the presence of minerals such as pyrite (FeS₂). It has been proven for Fe(II) that Tc(VII) reduction is more favorable when Fe(II) takes part in the mineral structure or it is sorbed on a surface than when Tc(VII) reduction is carried by dissolved Fe(II) homoreduction) [3]. We have recently showed that Tc(VII) heteroreduction (reduction occurring at the mineral-water interface) by Fe(II) pre-sorbed on alumina nanoparticles is highly efficient [4].
Thus, in this work, we have studied kinetically as a function of pH: i) S(-II) sorption on alumina, and ii) subsequent Tc uptake promoted by S(-II) pre-sorbed on alumina. We have also focused on the effect of different sulfide sources on Tc(VII) reduction. All the experiments were performed in a N₂ glove box free of CO₂ and O₂ (< 2 ppm). The alumina
nanoparticles used in the experiments has been previously characterized with 127 m² /g N₂ BET and pH 9 as isoelectric point pH [5]. For the batch sorption experiments, suspensions of alumina (0.5 g/L) containing 50 μM of NaHS at pH 5.3, 6.7 and 7.7 were prepared and shaken for two days. Then, KTcO₄ was added to the suspensions to obtain 5 μM of KTcO₄. Subsequently, the suspensions were placed in a horizontal shaker. The suspension pH was monitored frequently and readjusted when needed. Samples were taken periodically and centrifuged at 14,000 rpm for 45 min. The Tc concentration in the supernatant solution was measured by liquid scintillation counter to determine the percentage of Tc removed.
Figure 1 shows the uptake of Tc in % as a function of time and pH. Tc removal increases with decreasing pH. This is in agreement with the highest anion sorption on alumina nanoparticles at lower pH, when alumina surface is positive charged [5]. The maximum Tc retention is 70% at pH 5.3, being complete after one day of contact. Whereas at higher pH values, Tc removal is significantly lower, i.e., 10% at pH 6.7 and 5% at pH 7.7. It is noteworthy to mention that the NaHS reactant used for the experiments in Figure 1. was partially oxidized. Despite of its oxidation, reduction of Tc(VII) yield at pH 5.3 was above 70% after one day of contact.

Further contact experiments have been performed to isolate the contribution of S(-II) in Tc(VII) heteroreduction, and the effect of the sulfide source on Tc removal. Raman microscopy and X-ray absorption spectroscopy have been used to determine the changes occurring at a molecular level when Tc(VII) is heteroreduced by S(-II).

Acknowledgements: The authors acknowledge the Spanish Ministry of Research and Universities for the abroad internship fellowship (PRE2018-085618) and the project (ENE2017-83048-R). Part of this work was financially supported by the German Federal Ministry of Education and Research (BMBF) NukSiFutur TecRad young investigator group (02NUK072).

This contribution provides an overview of a current research network funded by the German Federal Ministry of Education and Research (BMBF), entitled “Fundamental investigations of actinide immobilization by incorporation into solid phases relevant for final disposal” – AcE. The AcE project aims at understanding the incorporation and immobilization of actinides (An) in crystalline, repository-relevant solid phases, such as zirconia (ZrO2) and UO2, but also in zircon (ZrSiO4), pyrochlores (Ln2Zr2O7) and orthophosphates of the monazite type (LnPO4), which may find use as host matrices for the immobilization and safe disposal of high-level waste streams.
Recent studies by the AcE-project consortium, addressing the structure, properties, and the radiation tolerance of monazites and Zr(IV)-based solid phases containing actinides or their surrogates from the lanthanide series will be presented. Material synthesis strategies in the AcE project have aimed at generating single-phase solid solutions in the form of polycrystalline powders, dense ceramics, and single crystals. Structural studies using powder X-ray diffraction at ambient conditions, but also at high temperatures and pressures have been complemented with a wide range of microscopic and spectroscopic techniques to address differences between the host- and dopant environments in the solid matrices at ambient and extreme conditions. The radiation tolerance of the synthetic solid phases have been investigated by combining external heavy-ion irradiation of inactive Ln-doped materials and in situ self-irradiation of 241Am-doped Zr(IV)-phases with monoclinic, cubic defect fluorite and pyrochlore structures. The latter experiments have been conducted in joint efforts with the Joint Research Center in Karlsruhe within the ActUsLab programme.

Complex flow patterns frequently emerge when a surface active substance undergoes mass transfer between an organic and an aqueous phase. At the same time, density effects can play a major role, e.g. during the partial dissolution of floating organic droplets \cite{cejkova2019dancing}. The resulting droplet ensemble dynamics can be understood by highly resolved measurements of the transient velocity field via particle image velocimetry (PIV). At bubbles in a shear flow, the interaction of the Marangoni effect with the surrounding bulk flow leads to the formation of a circulating flow at the bubble surface \cite{eftekhari2021interfacial}. Bubbles or droplets which are placed in a vertical concentration gradient of a surface-active solute show an intriguing interaction of solutal Rayleigh and Marangoni convection in the form of relaxation oscillations \cite{mokbel2018information}. Depending on the distance between multiple droplets, convective interaction can lead to collective relaxation oscillations over the whole ensemble.

A repeated coupling of Rayleigh and Marangoni effects likewise can occur during mass transfer of a solute at a planar interface between two liquid layers. Solutal Rayleigh instability is able to provoke intense Marangoni-driven spreading motions at the interface, even if the mass transfer system is primarily stable towards stationary Marangoni convection \cite{koellner2016eruptive}. A more detailed study \cite{koellner2023eruptive} unravels the underlying mechanisms by a defined variation of key parameters: the layer height and the initial concentration of the solute. The flow structures are analyzed in detail by experiments and elaborate three-dimensional simulations of the two liquid layers. The flow in the interfacial region decouples from the bulk volume flow since for deep layers, the interfacial velocity gets invariant under a change of the nondimensional layer height. Due to the additional convection, mass transfer is strongly enhanced in comparison to the purely diffusive process. This can significantly increase the efficiency of liquid-liquid extraction processes.

\bibitem{cejkova2019dancing} J.~{\v{C}}ejkov{\'a}, K.~Schwarzenberger, K.~Eckert, S.~Tanaka, Colloids and Surfaces A, 566, 141 (2019)
\bibitem{mokbel2018information} M.~Mokbel, K.~Schwarzenberger, S.~Aland, K.~Eckert, Soft Matter, 14, 9250 (2018)
\bibitem{eftekhari2021interfacial} M.~Eftekhari, K.~Schwarzenberger, S.~Heitkam, K.~Eckert, Journal of Colloid and Interface Science, 599, 837 (2021)
\bibitem{koellner2016eruptive} T.~K{\"o}llner, K.~Schwarzenberger, K.~Eckert, T.~Boeck, Journal of Fluid Mechanics, 791, R4 (2016)
\bibitem{koellner2023eruptive} T.~K{\"o}llner, K.~Schwarzenberger, K.~Eckert, T.~Boeck, in progress (2023)

The shear stress of an axisymmetric flow field triggers a nonuniform distribution of adsorbed
surfactants at the surface of a rising bubble. This creates a surface tension gradient that
counteracts the viscous shear stress of the flow and thus reduces the mobility of the interface.
However, in technological processes the flow field often is asymmetric, e.g. due to the
vorticity in the flow. Under such conditions, the interface experiences an unbalanced shear
stress that is not free of curl, i.e. it cannot be compensated by the redistribution of the surfactants
at the interface (Vlahovska et al., 2009). Here, we conduct model experiments with
a bubble at the tip of a capillary placed in a defined asymmetric flow field, in the presence of
surfactants and nanoparticles. Unlike classical surfactants, nanoparticles adsorb irreversibly
at the bubble surface. Thus, a different interaction between the bulk flow and the interface
is expected. In this study, we show a direct experimental observation of the circulating flow
at the interface under asymmetric shear stress (Eftekhari et al., 2021a,b). The results indicate
that the interface remains mobile regardless of the surfactant concentration. Additionally, we
show that the nanoparticle-laden interface adopts a solid-like state and resists the interfacial
flow upon surface compression. Our results imply that the immobilization of the interface
can be described by the ratio of the interfacial elasticity to the bulk viscous forces.
Vlahovska, P. M., Bławzdziewicz, J., & Loewenberg, M. (2009). Small-deformation theory for a
surfactant-covered drop in linear flows. J.Fluid Mech., 624, 293.
Eftekhari, M., Schwarzenberger, K., Heitkam, S., & Eckert, K. (2021). Interfacial flow of a surfactant-
laden interface under asymmetric shear flow. J. Colloid Interface Sci., 599, 837.
Eftekhari, M., Schwarzenberger, K., Heitkam, S., Javadi, A., Bashkatov, A., Ata, S., & Eckert, K.
(2021). Interfacial behavior of particle-laden bubbles under asymmetric shear flow. Langmuir,
37, 13244.

Die Grenzflächenkonvektion (Marangoni-Effekt) ist eine kleinskalige Strömung, die
durch Gradienten der Grenzflächenspannung verursacht wird. Sie beeinflusst den
Stofftransport und die Strömungsbedingungen in einer Vielzahl von natürlichen und
technologischen Prozessen. Grenzflächenkonvektion kann an Tropfen oder Blasen
beobachtet werden, die in einem vertikalen Konzentrationsgradienten einer gelösten
grenzflächenaktiven Substanz platziert werden [1,2]. Die Frequenz der
Strömungswirbel wird direkt vom anliegenden Konzentrationsgradienten des
gelösten Stoffs bestimmt. Mehrere benachbarte Tropfen oder Blasen (Abb. 1, links)
synchronisieren sich durch konvektive Interaktion zu Oszillationen über das gesamte
Ensemble. Die genannten Erkenntnisse werden durch numerische Simulationen
bestätigt.
Abbildung 1: Wechselwirkung von Grenzflächenkonvektion an benachbarten Tropfen (links [2]),
Geschwindigkeitsfeld um zwei schwimmende Decanoltropfen (mittig [4]), asymmetrische
Bulkströmung um partikelbeladene Blasenoberfläche (rechts)
Grenzflächenkonvektion beeinflusst zudem die Dynamik von schwimmenden
Dichlormethan- und Decanoltropfen [3,4]. Durch zeitlich und örtlich hochaufgelöste
Particle Image Velocimetry (PIV)-Messungen kann der Einfluss der
Grenzflächenkonvektion auf die Deformation und Interaktion der schwimmenden
Tropfen verstanden werden (Abb. 1, mittig).
1 mm
Mit dieser Technik konnte auch zum ersten Mal eine kontinuierliche
Grenzflächenkonvektion auf der Blasenoberfläche aufgrund einer asymmetrischen
Scherkraft durch die anliegende Bulkströmung visualisiert werden [5]. In diesem
Prozess bleibt die Grenzfläche unabhängig von der Konzentration eines klassischen
Tensids mobil. Bei Adsorption von Partikeln auf der Blasenoberfläche nimmt die
Mobilität der Grenzfläche jedoch ab (Abb. 1, rechts). Durch eine Kompression der
Oberfläche bildet sich weiterhin ein zusammenhängendes Netzwerk aus Partikeln,
das die Grenzflächenkonvektion schließlich zum Erliegen bringt [6].
Dies zeigt, dass in Abhängigkeit von der Art des adsorbierten Stoffs deutlich
unterschiedliche Randbedingungen für die Strömung an der Grenzfläche von Tropfen
und Blasen vorherrschen können [7]. Die kleine Längenskala der
Grenzflächenkonvektion eröffnet zudem die Möglichkeit, diesen Effekt zur passiven
Durchmischung [8] oder zur Informationsübertragung in mikrofluidischen Prozessen
zu nutzen [2].
Publikationen:
[1] Schwarzenberger, K., Aland, S., Domnick, H., Odenbach, S., & Eckert, K. (2015). Relaxation
oscillations of solutal Marangoni convection at curved interfaces. Colloids and Surfaces A, 481, 633.
[2] Mokbel, M., Schwarzenberger, K., Aland, S., & Eckert, K. (2018). Information transmission by
Marangoni-driven relaxation oscillations at droplets. Soft Matter, 14(45), 9250.
[3] Antoine, C., Irvoas, J., Schwarzenberger, K., Eckert, K., Wodlei, F., & Pimienta, V. (2016). Selfpinning
on a liquid surface. The Journal of Physical Chemistry Letters, 7(3), 520.
[4] Čejková, J., Schwarzenberger, K., Eckert, K., & Tanaka, S. (2019). Dancing performance of
organic droplets in aqueous surfactant solutions. Colloids and Surfaces A, 566, 141.
[5] Eftekhari, M., Schwarzenberger, K., Heitkam, S., & Eckert, K. (2021). Interfacial flow of a
surfactant-laden interface under asymmetric shear flow. Journal of Colloid and Interface Science, 599,
837.
[6] Eftekhari, M., Schwarzenberger, K., Heitkam, S., Javadi, A., Bashkatov, A., Ata, S., & Eckert, K.
(2021). Interfacial Behavior of Particle-Laden Bubbles under Asymmetric Shear Flow. Langmuir,
37(45), 13244.
[7] Keshavarzi, B., Krause, T., Sikandar, S., Schwarzenberger, K., Eckert, K., Ansorge-Schumacher,
M. B., & Heitkam, S. (2022). Protein enrichment by foam Fractionation: Experiment and modeling.
Chemical Engineering Science, 256, 117715.
[8] Bratsun, D., Kostarev, K., Mizev, A., Aland, S., Mokbel, M., Schwarzenberger, K., & Eckert, K.
(2018). Adaptive micromixer based on the solutocapillary Marangoni effect in a continuous-flow
microreactor. Micromachines, 9(11), 600.

Active systems – including sperm cells, living organisms like bacteria, fish, birds, or active soft matter systems like synthetic “microswimmers” – are characterized by motility, i.e., the ability to propel using their own “engine”. Motility is the key feature that distinguishes active systems from passive or externally driven systems. In a large ensemble, motility of individual species can vary in a wide range. Selecting active species according to their motility represents an exciting and challenging problem. We propose a new method for selecting active species based on their motility using an acoustofluidic setup where highly motile species escape from the acoustic trap. This is demonstrated in simulations and in experiments with self-propelled Janus particles and human sperm. The immediate application of this method is selecting highly motile sperm for medically assisted reproduction (MAR). Due to the tunable acoustic trap, the proposed method is more flexible than the existing passive microfluidic methods. The proposed selection method based on motility can also be applied to other active systems that require selecting highly motile species or removing immotile species.

Thin films of the magnetoelectric insulator Cr$_{2}$O$_{3}$ are technologically relevant for energy-efficient magnetic memory devices controlled by electric fields. We experimentally investigated the defect nanostructure of 250-nm-thick Cr$_{2}$O$_{3}$ thin films prepared under different conditions on single crystals of Al$_{2}$O$_{3}$ (0001) and correlate it with the integral and local magnetic properties of the samples. Positron annihilation spectroscopy (PAS) was used as a unique probe for open-volume defects in thin films. Analysis reveals that the Cr$_{2}$O$_{3}$ thin films are characterized by the presence of complex defects at grain boundaries, formed by groups of monovacancies, coexisting with monovacancies and dislocations. The concentration of complex defects can be controlled by the sample fabrication conditions. The defect nanostructure strongly affects the magnitude of the electrical readout, which is measured of the Cr$_{2}$O$_{3}$ samples capped with a thin layer of Pt relying on spin Hall effect. Furthermore, the presence of larger defects like grain boundaries has a strong influence on the pinning of magnetic domain walls in thin films. Independent of these findings, we showed that the N\'{e}el temperature, which is one of the important technological metrics, is hardly affected by the formed defects in a broad range of deposition parameters.

Thin films of antiferromagnetic insulators (Cr2O3, Fe2O3, NiO etc.) are a prospective material platform for magnonics, spin superfluidity, THz spintronics, and non-volatile data storage. A standard micromagnetic approach for the description of thin film system commonly relies on the effective parameters, assumed to be homogeneously distributed within a material. The family of magnetomechanical effects includes piezo- and flexomagnetic responses, which determine the modification of the magnetic order parameters due to homogeneous or inhomogeneous strain, respectively. Accounting for the strain-gradient-driven magnetomechanical coupling promises technological advantages: the cross-coupling between elastic, magnetic and electric subsystems opens additional degrees of freedom in the control of the respective order parameters [1]-[3].
In this work, we discover the presence of flexomagnetic effects in epitaxial antiferromagnetic Cr2O3 thin films [4]. We demonstrate that a gradient of mechanical strain affect the order-disorder magnetic phase transition resulting in the distribution of the Néel temperature along the thickness of Cr2O3 thin film. The inhomogeneous reduction of the antiferromagnetic order parameter induces a flexomagnetic coefficient of about 15 µB nm-2. The antiferromagnetic ordering in the strained films can persist up to 100 °C, rendering Cr2O3 as a prospective material for industrial spintronic applications. Strain gradient in Cr2O3 thin films enables fundamental research on magnetomechanics and thermodynamics of antiferromagnetic solitons, spin waves and artificial spin ice systems in magnetic materials with continuously graded parameters.

Thin films of magnetoelectric antiferromagnetic insulators (Cr2O3, BiFeO3 etc.) have emerged as a prospective material platform for magnonics, spin superfluidity, THz spintronics, and energy efficient spin-orbitronics. Understanding the magnetomechanical coupling in antiferromagnets offers vast advantages in the control of the primary order parameters. A standard micromagnetic approach for the description of a material relies on the effective parameters being homogeneously distributed throughout the system. Such an approach is commonly sufficient, but does not provide full characterization of the system. The family of magnetomechanical effects includes piezo- and flexomagnetic responses, which determine the modification of the magnetic order parameters due to homogeneous or inhomogeneous strain, respectively. Accounting for the flexomagnetic effects promises technological advantages for multiferroic and antiferromagnetic materials, where cross-coupling between elastic, magnetic and electric subsystems open additional degrees of freedom in the control of the respective order parameters [1, 2].
In this work, we discover the effect of strain gradient onto the magnetic behaviour of epitaxial Cr2O3 thin films [3, 4]. We demonstrate that by tuning the parameters of Cr2O3 epitaxial growth a fine control of the crystallographic and defect structure can be realized. A persistent strain gradient was obtained in Cr2O3 affecting its magnetic order parameters rendering a distribution of the Néel temperature along the thickness of the thin film. The antiferromagnetic ordering in the strained films can persist up to 100°C, rendering Cr2O3 as a prospective material for industrial electronics applications. The inhomogeneous enhancement of the antiferromagnetic order parameter induced by the strain gradient renders a flexomagnetic response of about 15 µB nm-2.
Strain gradient in Cr2O3 thin films enables fundamental research on magnetomechanics and thermodynamics of antiferromagnetic solitons, spin waves and artificial spin ice systems in magnetic materials with graded parameters. Distribution of the Neel temperature along the thin film thickness introduces temperature as a took for realization of reconfigurable spintronic and magnonic devices.

Thin films of antiferromagnetic insulators are a prospective material platform for magnonics, spin superfluidity, THz spintronics, and nonvolatile data storage. Here, we explore the presence of flexomagnetic effects in epitaxial Cr2O3 [1]. We demonstrate that a gradient of mechanical strain effect the order-disorder magnetic phase transition, resulting in the distribution of the Néel temperature along the thickness of a Cr2O3 film. The inhomogeneous reduction of the antiferromagnetic order parameter induces a flexomagnetic coefficient of about 15µB nm−2. The
antiferromagnetic ordering in the strained films can persist up to 100∘C, rendering Cr2O3 as a prospective material for industrial electronics applications.

Im Zeitalter der datengestützten Entscheidungsfindung hat sich der Bereich Datenwissenschaft (Data Science) zu einem wichtigen Katalysator für Innovation und Fortschritt sowohl in der Industrie als auch in der Wissenschaft entwickelt. Die Rollen und Aufgaben von Data Scientists haben sich jedoch erheblich weiterentwickelt und umfassen ein breites Spektrum an Fähigkeiten, Fachwissen und Anwendungen. Um die Vielschichtigkeit dieser Rollen zu erfassen und unser kollektives Verständnis zu vermitteln, traf sich eine Gruppe von sechs Fachleuten bei Silicon Saxony und nutzte "Personas" als Methode, um unsere derzeitigen Ansichten über die Rolle von Datenwissenschaftler:innen zu formulieren. Dieses Papier fasst die Erkenntnisse dieser Aktivität zusammen.

The main quantity of interest in radiotherapy dosimetry is absorbed dose to water, i.e. the energy that is deposited by the radiotherapy beam in water per unit mass. The most common method to measure dose in radiotherapy is by using air-filled ionization chambers via the charge released in their active volume by ionizations. These ionization chambers are typically absolute calibrated in 60Co beams in terms of absorbed dose to water. If a measurement is carried out in another radiation quality (e.g. proton beams), the different response of the chamber in that radiation quality compared to 60Co photons due to a different water-to-air stopping power ratio and chamber-specific geometry effects is taken into account by applying a beam quality correction factor kQ. Because kQ might be sensitive to several factors, it is recommended that absolute absorbed dose to water measurements should be performed within defined reference conditions (e.g. field size and water depth), and therefore such measurements are referred to as reference dosimetry [1]. In addition to kQ, also several other corrections may be necessary (e.g., recombination or air density correction).
Compared to ionization chamber dosimetry, a more direct way to measure dose is calorimetry where the deposited energy in the detector is measured via its temperature increase. Calorimetry is considered as the most accurate method of dose determination but requires a large logistic effort, stable thermal conditions in the room plus a good isolation and those devices are usually very sensitive and complicated to operate. Therefore calorimetry is at present mostly applied as primary standard for absorbed dose in permanently installed setups at national metrology institutes [2], to which the calibration of ionization chambers used in radiotherapy clinics can be traced back to.
The natural choice of the calorimeter medium is water because absorbed dose to water is the quantity of interest in radiotherapy dosimetry. Due to some practical limitations of water calorimeters, there are also calorimeter designs based on solid materials, typically graphite. Graphite calorimeters can be a lot more compact than water calorimeters and due to the smaller specific heat capacity of graphite, the temperature increase (i.e., the measurement signal) is about a factor 5 higher than for water at the same dose. However, the higher thermal conductivity of graphite requires additional insulation of the calorimeter core. Another characteristic of graphite calorimetry is that it requires a conversion from absorbed dose to graphite to absorbed dose to water and therefore the stopping power ratio in the radiation field of interest must be calculated.
Besides applications as primary standard for absorbed dose to water, calorimetric measurements can also be helpful to guarantee the dosimetric accuracy when novel radiotherapy modalities, for which standard dosimetry protocols are not suitable, are introduced. Recent examples are magnetic resonance guided radiotherapy [3], where the response of ionization chambers is modified by the magnetic field, or FLASH radiotherapy at ultra-high dose rate (UHDR) [4,5] where recombination effects in ionization chambers become more pronounced than in conventional radiotherapy. For calorimetric measurements, the UHDR delivery can even be considered an advantage because the quasi-instantaneous dose application makes the heat drift become less relevant. For instance at the Physikalisch-Technische Bundesanstalt (PTB) in Germany, efforts were made to establish a water calorimeter as primary standard in the UHDR beam of their 20 MeV electron accelerator [4]. Another example is the first proton FLASH patient trial at the Cincinnati Children’s Hospital Medical Center in the USA where a group from the National Physical Laboratory (NPL) of the United Kingdom supported the dosimetric characterization of UHDR beams with their graphite calorimeter [5]. Recently, water calorimeters have been used to determine ionization chamber specific beam quality correction factors in clinical proton (6) and carbon ion beams [7,8].
Generally, for protons and heavy ions no actual primary standards have been established up to now [9], because the national metrology institutes do not have suitable accelerators and beam qualities on-site but would have to travel to clinical facilities with their calorimetry equipment. For this purpose, since several years many metrology groups work on the development of portable calorimeters (see for example ref. [10] for an early work).
At NPL a portable graphite calorimeter was developed [11]. This device is now intended to be applied for secondary standard measurements in UHDR proton beams in order to improve the dosimetric accuracy for this novel radiotherapy modality. Like ionization chamber dosimetry, also calorimetry requires a number of correction factors to be applied to the measured signal. Cotterill and colleagues present in their paper [12], published in this ESTRO 2023 Physics Highlights special issue of phiRO, detailed Monte Carlo simulations on their so-called Small-body Portable Graphite Calorimeter. They derived correction factors for 250 MeV protons correcting for the graphite impurity and the air gap between the graphite core and its jacket. They show that the dominating perturbation (almost 0.5%) is due to missing scatter contributions from the styrofoam insulation around the device, for which they introduce a new correction factor. By applying the obtained correction factors, the dosimetric accuracy of the calorimeter can be improved considerably. The in- and out-scattering of protons from the different components of the device was studied in detail and the dose conversion factor from absorbed dose in the graphite core to absorbed dose to water at the reference point was calculated.
Even though portable calorimeters like the one presented by Cotterill et al. are still more complicated to operate than ionization chambers, they are much more convenient to transport and set up than classic calorimetry setups.
It will be very interesting to see if these developments will contribute to a wider spread of calorimetric measurements in radiotherapy, or even a routine use in radiotherapy clinics as envisioned by Cotterill et al., and if the establishment of a primary standard for absorbed dose to water in proton (and heavy ion) beams will finally succeed.

Matter under extreme densities and temperatures is ubiquitous throughout our universe and naturally occurs in a plethora of astrophysical objects such as giant planet interiors and brown dwarfs. In addition, such warm dense matter (WDM) is of key importance for a number of technological applications, most notably inertial confinement fusion. Yet, the accurate diagnostics of experiments with WDM is rendered challenging by the extreme conditions. Indeed, even basic parameters such as the temperature often cannot be measured directly and have to be inferred from other observations. In this context, X-ray Thomson scattering (XRTS) [1] has emerged as a key diagnostic, but the interpretation of an XRTS signal is often based on de-facto uncontrolled approximations such as the decomposition into bound and free electrons within the popular Chihara model.

In this contribution, I outline how one can get direct access to the physical properties of interest by analyzing the measured signal in the imaginary-time domain [2]. No simulations/models and, therefore, no approximations are required. First and foremost, this allows us to infer the temperature of a given system with high accuracy [3]. Moreover, we can use XRTS to probe electron—electron correlations by utilizing the f-sum rule in the imaginary-time domain [4]. Finally, we show how the idea of imaginary-time correlation functions can be generalized to characterize the degree of nonequilibrium in the probed system [5], with important implications for equation-of-state measurements and the understanding of relaxation times.

[1] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)

[2] T. Dornheim et al, arXiv:2209.02254 (submitted)

[3] T. Dornheim et al, Nature Communications 13, 7911 (2022)

[4] T. Dornheim et al, arXiv:2305.15305 (submitted)

[5] J. Vorberger et al, arXiv:2302.11309 (submitted)

We report the formation of a Np(IV) complex from the complexation of Np(VI)O22+ with the redox-active ligand tBu-pdiop2-=2,6-bis[N-(3,5-di-tert-butyl-2-hydroxyphenyl)iminomethyl]pyridine. To the best of our knowledge, this is the first example of the direct complexation-induced chemical reduction of Np(VI)O22+ to Np(IV). In contrast, the complexation of U(VI)O22+ with tBu-pdiop2- did not induce the reduction of U(VI)O22+, not even after the two-electron electrochemical reduction of [U(VI)O2(tBu-pdiop)]. This contrast between the Np and U systems may be ascribed to the decrease of the energy of the 5f orbitals in Np compared to those in U. The present findings indicate that the redox chemistry between U(VI)O22+ and Np(VI)O22+ should be clearly differentiated in redox-active ligand systems.

Extended-gate field-effect transistor (EG-FET) chemo- and biosensors are emerging tools for a wide range of biomedical applications. Significant efforts have been made to make them ultrasensitive to biomolecules via the development of miniaturized sensing transistors, design and optimization of extended gate sensing layer, exploration of the multiplexing ability of EG-FET configuration, and advanced data analysis. Here, we specifically focus on several important aspects related to the construction and current applications of EG-FET sensors. Namely, we review the materials, fabrication, properties of the transducer, specificities of the conditioning electronics, and signal analysis. At the same time, we discuss the current drawbacks of these sensors preventing their straightforward commercialization, such as output signal variation and non-linearities of the response. We also review the recent key applications of EG-FET sensors in the areas of early medical diagnostics, ecology, food and chemical industries, and others. Finally, we briefly discuss the future perspectives in the development of this class of sensors.

We study THz-driven condensate dynamics in epitaxial thin films of MgB2, a prototype two-band superconductor (SC) with weak interband coupling. The temperature and excitation density dependent dynamics follow the behavior predicted by the phenomenological bottleneck model for the single-gap SC, implying adiabatic coupling between the two condensates on the ps timescale. The amplitude of the THz-driven suppression of condensate density reveals an unexpected decrease in pair-breaking efficiency with increasing temperature—unlike in the case of optical excitation. The reduced pair-breaking efficiency of narrow-band THz pulses, displaying minimum near ≈0.7  Tc, is attributed to THz-driven, long-lived, nonthermal quasiparticle distribution, resulting in Eliashberg-type enhancement of superconductivity, competing with pair breaking.

The use of focused ion beams for sensitively controlling the intrinsic magnetic as well as transport properties at the nanoscale requires materials, wherein small atomic displacements results in large property changes. Typical examples are binary alloys consisting of a 3d metal such as Fe and elements such as Al [1], Rh [2] and most recently, V [3]. These materials act as non-ferromagnetic templates onto which atomic reordering within confined regions can be used to realize the direct writing of ferromagnetism. These alloys are deployed as prototypes for exploring nanoscale ion-induced property modulation.

The type of phase transition may vary, for instance, a transition in the chemical order of Fe60Al40 in contrast with the emergence of a crystalline lattice from a short-range ordered structure in Fe60V40. Due to chemical disordering, the localized ferromagnetic in the former alloy imparts spin scattering that can be observed in the anomalous Hall effect, whereas in the latter, the lattice reordering propagates in a layer like fashion providing homogenous ferromagnetic layers. The phase transition characteristics influence their potential applications, such as in ferromagnetic resonance and transport.

Observations of the evolving nearest-neighbour environment of atoms as a function of the atomic displacements helps unravel some of the microscopic processes leading to the large intrinsic property changes. This current research is being performed with the help of large-scale facilities, such as the Ion-Beam-Centre as well as the ELBE at HZDR.

References:

1. S. Sorokin et al., New J. Phys. (2023).
2. W. Griggs et al., APL Materials (2020) 8, 121103.
3. Md. S. Anwar et al., ACS Appl. Elec. Mater. (2022) 4, 8, 3860.

Researchers are continuously developing novel methods and algorithms in the field of applied uncertainty quantification (UQ).
During the development phase of a novel method or algorithm, researchers and developers often rely on test functions taken from the literature for validation purposes.
Afterward, they employ these test functions as a fair means to compare the performance of the novel method against that of the state-of-the-art methods in terms of accuracy and efficiency measures.

UQTestFuns is an open-source Python3 library of test functions commonly used within the applied UQ community.
Specifically, the package provides:

• an implementation with minimal dependencies (i.e., NumPy and SciPy) and a common interface of many test functions available in the UQ literature
• a single entry point collecting test functions and their probabilistic input specifications in a single Python package
• an opportunity for an open-source contribution, supporting the implementation of new test functions and posting reference results.

UQTestFuns aims to save the researchers' and developers' time from having to reimplement many of the commonly used test functions themselves.

In this presentation I will describe our recent experiments with polycrystalline Bi thin films, where we observed non-linear Hall effect.

We investigate superradiant enhancements in the refrigeration performance in a set of N three-level systems that are collectively coupled to a hot and a cold thermal reservoir and are additionally subject to collective periodic (circular) driving. Assuming the system-reservoir coupling to be weak, we explore the regime of stronger periodic driving strengths by comparing collective weak-driving, Floquet-Lindblad, and Floquet-Redfield master equations. We identify regimes where the power injected by the periodic driving is used to pump heat from the cold to the hot reservoir and derive analytic sufficient conditions for them based on a cycle analysis of the Floquet-Lindblad master equation. In those regimes, we also argue for which parameters collective enhancements like a quadratic scaling of the cooling current with N can be expected and support our arguments by numerical simulations.

As a simplified description of the non-equilibrium dynamics of buckled dimers on the Si(001) surface, we consider the anisotropic 2D Ising model and study the freezing of spatial correlations during a cooling quench across the critical point. The dependence of the frozen correlation lengths ξ‖ and ξ⊥ on the cooling rate obtained numerically matches the Kibble-Zurek scaling quite well. However, we also find that the ratio ξ‖/ξ⊥ of their frozen values deviates significantly from the ratio in equilibrium. Supported by analytical arguments, we explain this difference by the fact that the deviation from equilibrium in the weakly coupled direction occurs earlier than in the strongly coupled direction.

External piecewise-constant feedback control can modify energetic and entropic balances, allowing in extreme scenarios for Maxwell demon operational modes. Without specifying the actual implementation of external feedback loops, one can only partially quantify the additional contributions to entropy production. This is different in autonomously operating systems with internal feedback. Traditional (bipartite) autonomous systems can be divided into controller and a controlled subsystem, but also non-bipartite systems can accomplish the same task. We consider examples of autonomous three-terminal models that transfer heat mainly from a cold to a hot reservoir by dumping a small fraction of it to an ultra-cold (demon) reservoir, such that their coarse-grained dynamics resembles an external feedback loop. We find that the minimal three-level implementation is most efficient in utilizing heat dissipation to change the entropy balance of the effective controlled system.

For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and its association with osteolysis and implant loosening. The surface morphology, chemistry, phase analysis, and surface chemistry of retrieved and new Al2O3 grit-blasted titanium alloy were determined with scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and confocal laser fluorescence microscopy, respectively. Peri-prosthetic soft tissue was studied with histopathology. Blasted retrieved and new stems were exposed to human mesenchymal stromal stem cells (BMSCs) for 7 days to test biocompatibility and cytotoxicity. We found metallic particles in the peri-prosthetic soft tissue. Ti6Al7Nb with the residual Al2O3 particles exhibited a low cytotoxic effect while polished titanium and ceramic disks exhibited no cytotoxic effect. None of the tested materials caused cell death or even a zone of inhibition. Our results indicate a possible biological effect of the blasting debris; however, we found no significant toxicity with these materials. Further studies on the optimal size and properties of the blasting particles are indicated for minimizing their adverse biological effects.

Ensuring the biocompatibility of hip implants is essential for the safety, effectiveness, and longevity of these medical devices [1]. The material-induced tissue inflammation and immune reaction must be negligible while promoting tissue integration. However, the major unresolved issue in joint replacement is the occurrence of adverse biological reactions to wear debris, leading to severe inflammation [2] which has been observed at the subcellular level [3]. To gain a deeper understanding of the biocompatibility related to material chemistry and surface topography and to better predict the material functionality and clinical use, it is crucial to investigate the properties of cell adhesion, proliferation, and migration on the implant's surface. In this study, we demonstrate how Al2O3-coated titanium alloys with varying surface topographies and roughness affect the growth and morphology of human bone marrow mesenchymal stromal cells (BM-MSCs). This subcellular-level investigation was conducted on live cells using novel high-resolution 3D confocal fluorescence and backscatter microscopy.

1. Hu CY, Yoon TR. Biomaterials Research, 2018, 22, 33.
2. Cobelli N, Scharf B, Crisi GM, Hardin J, Santambrogio L. Nat Rev Rheumatol. 2011, 7, 600–608.
3. Podlipec R, Punzón-Quijorna E, Pirker L, Kelemen M, Vavpetič P, Kavalar R, Hlawacek G, Štrancar J, Pelicon P, Fokter SK, Materials, 2021, 14, 3048.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and
temperatures---has emerged as one of the most active frontiers in plasma physics and material
science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown
dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as
inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied
experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics
based on accurate theoretical modeling, which is a notoriously difficult task [1].
In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will
present a model-free temperature diagnostic [4] based on the well-known principle of detailed
balance, but available for all wave numbers, and a new idea to directly extract the electron—
electron static structure factor from an XRTS measurement [5]. As an outlook, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.
[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

Renewable energy sources are the key for long-term decarbonisation of the energy system. However, the intermittent nature of renewables, such as solar energy or wind energy, does not always meet the energy demand in the electrical grid. Considering the fact that both electricity production and consumption vary independently, balancing the grid is a major challenge for the development of an energy system based on renewable energies. Within this framework, Thermal Energy Storage systems (TES) coupled with a power cycle have gained popularity since they can store energy from renewable sources during the periods of high production and release it when necessary.
To convert thermal energy into electricity, a power cycle is required. Given the relative high temperature range (600 - 1000 °C), supercritical CO2 (sCO2) is the most promising material as working fluid for the power cycle, from efficiency and safety considerations. Thus, the Primary Heat Exchanger (PHX) must be carefully designed as the fluid pressures in the TES and the power cycle are namely 1 - 10 bar and 200 - 250 bar.
The present work consists of two parts, one elaborates a 1D model in order to design the PCHE regarding a certain set of boundary conditions. The model requires heat transfer and pressure loss correlations from the literature to estimate the Nusselt number and friction factor, which strongly depends on the geometry. It was found that the zigzag channel design intensifies both heat transfer and pressure drop phenomena, which is not suitable for the hot fluid from an economic prospective. Furthermore, 3D simulations by Computational Fluid Dynamics (CFD) were done and compared to the results from the 1D model to ensure the validity of the correlations. It was also found that the results match those from the literature, thus validating the 1D model.

Presentation for PhD seminar

Für die Untersuchung des Radionuklidpaares 197(m)Hg in der Theranostik, ist die Entwicklung eines Radiopharmakons erforderlich, bei dem unter In-vivo-Bedingungen keine Dissoziation und somit keine Freisetzung von zytotoxischem Quecksilber stattfindet. Das potenzielle metallorganische Radiopharmakon soll dabei auf einem in vivo stabilen Bispidin-Grundgerüst basieren. Dieses bietet die Möglichkeit das Radionuklid durch einfache Substitution über eine benzylische Struktureinheit kovalent an das Grundgerüst zu binden. Durch die dreidimensionale Struktur erfährt das Radionuklid dabei eine sterische Abschirmung. Zusätzlich fungiert das Grundgerüst als bifunktioneller Ligand, der durch eine weitere Substitution in der C9-Position das PSMA-Bindungsmotiv binden kann.
Auf Grundlage der bisherigen Forschungsergebnisse soll das potenzielle Radiopharmakon auf einem Bispidin-Grundgerüst basieren. Hierfür müssen die pharmakologischen Eigenschaften wie die Lipophilie angepasst werden, was durch die Verwendung von Methylgruppen in den Positionen C1 und C5 erreicht werden soll. Weiterhin soll durch die gezielte Funktionalisierung der C9-Position des Bispidin-Grundgerüsts eine Bindung des PSMA-Bindungsmotivs an das Grundgerüst ermöglicht werden, wofür verschiedene Ansätze untersucht werden sollen. Das vorrangige Ziel besteht dabei in der Einführung und Funktionalisierung eines primären Amins und deren Substitution, um die Bindung des Vektormoleküls zu erreichen.
Nach Entfernung des C1-Bausteines aus dem Aminal soll durch nukleophile Substitution jeweils eine Trialkylstannyl-funktionalisierte Struktureinheit an den sekundären Aminen gebunden werden, um eine Fluchtgruppe für die folgende, kovalente Bindung des Quecksilbers zu ermöglichen. Hierfür soll einem vorangehenden Schritt das Trialkylstannyl-funktionalisierte Molekül synthetisiert werden. Basierend auf der Arbeit von I. M. GIPLIN und Kollegen soll statt der Trimethylstannyl- eine Triethylstannyl-Verbindung genutzt werden, um die beobachtete Instabilität zu umgehen.
Nachfolgend soll das PSMA-Bindungsmotiv über eine Peptidbindung an die funktionalisierte C9-Position des Grundgerüsts gebunden werden, wodurch sich das Radiopharmakon später selektiv an maligne Zellen anlagern kann. Darüber hinaus soll die anschließende Radiomarkierung mit dem Nuklidpaar 197(m)Hg ermöglicht werden.

In the first part, we present our recent result on mask-free nanofabrication involving a quasi-deterministic creation of single G- and W-centers in silicon wafers using focused-ion beam (FIB) writing. Using these centers, we implement a scalable, broad-beam implantation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabricate telecom single photon emitters at desired positions on the nanoscale In the second part, we present a concept of ultralong, high-density data archiving based on optically active atomic-size defects in silicon carbide (SiC). The information is written in these defects by FIB and read using photoluminescence (PL) or cathodoluminescence (CL). With near-infrared laser excitation, grayscale encoding and multi-layer data storage, the areal density corresponds to that of Blu-ray discs.

Understanding the composition of Earth's core and mantle is a major challenge in geoscience
and materials science. The core is primarily made of iron, but its density is known to be
slightly lower than pure iron. Hydrogen contributes to this density deficit, leading to
significant interest in the properties and structure of iron hydrides under high pressure.

Previous studies have shown that the dhcp phase of FeH remains stable at lower pressures (10-40 GPa)
but undergoes phase transitions to hcp and fcc phases at higher pressures.
This study focuses on a theoretical exploration of the potential energy surfaces (PESs) of FeH under
varying pressure conditions. The objective is to demonstrate the effectiveness of automated and systematic
methods for training and validating transferable machine-learned interatomic potential (ML-IAP) using global
optimization techniques. By utilizing this potential, which significantly reduce computational costs,
the phase diagram of the stoichiometric Fe-H system is analyzed across a range of pressures.

To achieve this, we utilize the PyFLAME code to construct a highly transferable ML-IAP.
With this accurate potential, the PESs of bulk FeH structures are systematically investigated
through global sampling using the minima hopping method. This comprehensive exploration enables the prediction
of stable and metastable iron hydrides from 0 to 100 GPa. Density functional theory calculations are conducted
to refine the predicted structures and evaluate their dynamical stability.
The findings of this study reveal a wide range of novel low-energy polymorphs of FeH at each
pressure level, alongside the recovery of well-known structures in the literature.

The formation of single bubbles at nanoelectrodes during electrochemical reactions allows to accurately identify the critical nucleus for bubble formation. As demonstrated before, combining nanoelectrode experiments and an analysis approach based on classical nucleation theory (CNT) delivers useful insight into bubble nucleation. In this work we propose an alternative approach to analyze the critical nuclei by applying the nucleation theorem (NT), which is able to overcome the inherent shortcomings of CNT. The size of the critical nucleus can be calculated more accurately by fitting experimental data in a simple form of the NT. Simulating the local gas concentration using a finite element approach, and considering the effect of gas oversaturation on the interfacial tension and the real gas compressibility, we obtain a more realistic estimation of the critical nuclei morphology. With the NT-based analysis presented, we re-analyze the nucleation data reported before. The properties of the critical nuclei obtained here are roughly consistent with those obtained from the CNT-based approach. In addition, we confirm that the critical nucleus for bubble formation in high gas oversaturation is featured with a contact angle much larger than Young’s contact angle.

Ion-cutting technology is an ingenious solution to the high-quality heterogeneous integration of GaN thin films with CMOS-compatible Si(100) substrate, which provides a platform to combine GaN-based optoelectronics, high-frequency and high-power electronics with digital signal processing, logic computation, and control of Si(100) CMOS. Previously, we reported the fabrication of 2-inch GaN film on SiO2/Si(100) substrate (GaNOI) by the ion-cutting technology. In this study, we further study the defect evolution in the transferred GaN films, which is needed to promote the practical applications of the GaNOI material platform.

Many countries consider clay rock formations as potential host rocks for high-level nuclear waste disposal. Clay rocks may exhibit heterogeneity on various scales, from the micro- to the facies-scale. In the Mont Terri rock laboratory, Switzerland, various experiments study properties and characteristics of the Jurassic Opalinus Clay, which is the target host rock for the Swiss nuclear waste repository but may also provide proxies for other considered clay rock formations. At Mont Terri, the Opalinus Clay mainly appears in a shaly and two sandy facies. So far, diffusion experiments at Mont Terri focussed on the relatively homogeneous shaly facies. The upper sandy facies (SF-OPA) exhibits a more pronounced internal – mineralogical and textural – heterogeneity. Clay rocks with comparable heterogeneity to SF-OPA may be present among the lower Cretaceous clay rocks of northern Germany, which are among the potential host rock candidates for a future German nuclear waste repository. Since 2020, seven institutions develop an in-situ diffusion experiment in SF-OPA, the so-called DR-D experiment, to explore the impact of rock heterogeneity on radionuclide diffusion in low permeability clay rocks.
So far, the DR-D experiment combined high-resolution seismic tomography, borehole logging, and detailed drill core analyses to characterize the heterogeneity of the selected SF-OPA area. The targeted rock zone exhibits a layer starting ca. 10 m below the gallery surface, which is characterized by relatively high seismic velocities. This layer is as well evident in the natural gamma- and the neutron backscattering logs. In the drill cores it stands out as whitish rock characterized by large concretions and traces of bioturbation in contrast to the dark layered clay-rock above and below with smaller concretions. Detailed analysis of seismic signals and drill-cores is still ongoing. In future, an in-situ diffusion test using various radioactive and non-radioactive tracers (e.g., HTO, 129I, 22Na) will be conducted targeting the evidently heterogeneous rock section 10 m below the gallery surface. The evolution of tracer concentrations in a synthetic porewater circulating in the diffusion interval will be monitored. A second seismic tomography survey is planned after the termination of the diffusion experiment. Finally, overcoring and post-mortem analysis of the rock affected by tracer diffusion will be used to determine the local variability of diffusion parameters.
In this contribution, we present the general concept, technical layout, and expected scientific impact of the DR-D experiment, as well as first results from field and related laboratory studies.

Electrochemical proton storage plays an essential role in designing next-generation high-rate energy storage devices, e.g., aqueous batteries. Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising electrode materials, but their competitive proton and metal-ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone-based poly(benzimidazobenzophenanthroline) (BBL)-ladder-type 2D c-COF for fast proton storage in both a mild aqueous Zn-ion electrolyte and strong acid. We unveil that the discharged C−O− groups exhibit largely reduced basicity due to the considerable π-delocalization in perinone, thus affording the 2D c-COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c-COF electrode presents an outstanding rate capability of up to 200 A g−1 (over 2500 C), surpassing the state-of-the-art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL-ladder-type 2D conjugated polymers in future energy devices.

Pseudomonas sp. are indigenous inhabitants of ombrotrophic bogs which can survive in acidic, nutrient-poor environments with wide temperature fluctuations. Their interactions with contaminant radionuclides can influence radionuclide biogeochemistry in boreal environment. Here, uranium (U(VI)) bioassociation by Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I isolated from a boreal bog was studied by a combination of batch contact experiments, spectroscopy and microscopy. All strains removed U from the solution and the U bioassociation efficiency was affected by the nutrient source, incubation temperature, time and pH. Highest U bioassociation occurred in the strains PS-0-L (0.199 mg U/gBDW) and V4-5-SB (0.223 mg U/gBDW). Based on in-situ attenuated total reflection Fourier transformation infrared spectroscopy (ATR FT-IR) analyses, the most likely functional groups responsible for U binding were the cell surface carboxyl groups. In addition, transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM/EDX) showed dense intra-cellular round- and needle-like U accumulations in the cytoplasm and near to the inner cell membrane. The presence of U with phosphorus was indicated in elemental mapping. Modelled data showed ≡SOOHx-1 and ≡SOCO2Hx-1 as the dominant surface sites, contributing to the negative cell surface charge. The U removal efficiency depended on the U(VI) speciation under different pH conditions. At pH 5, the main species reacting with bacterial cell surfaces was UO22+, while at pH 9 UO2(OH)2 and UO2(OH)3- dominated the reactions. Further, U bioassociation increased with increasing aqueous U(VI) concentrations. Our data suggests U bioassociation on 1) outer cell membrane/cell wall associated carboxyl groups (e.g., proteins), and 2) intracellular phosphate groups (e.g., phospholipids).

Hypothesis: The interactions between oppositely charged nanoparticles and surfactants can significantly influence the interfacial properties of the system. Traditionally, in the study of such systems, the nanoparticle concentration is varied while the surfactant concentration is kept constant, or vice versa. However, we believe that a defined variation of both components' concentration is necessary to accurately assess their effects on the interfacial properties of the system. We argue that the effect of nanoparticle-surfactant complexes can only be properly evaluated by keeping the surfactant to nanoparticle ratio constant.

Experiments: Zeta potential, dynamic light scattering, high amplitude surface pressure and surface tension measurements are employed synergistically to characterize the interfacial properties of the nanoparticle-surfactant system. Interferometric experiments are performed to highlight the effect of surface concentration on the stability of thin liquid films.

Findings: The interfacial properties of surfactant/nanoparticle mixtures are primarily determined by the surfactant/nanoparticle ratio. Below a certain ratio, free surfactant molecules are removed from the solution by the formation of surfactant-nanoparticle complexes. Surprisingly, even though the concentration and hydrophobicity of these complexes do not seem to have a noticeable impact on the surface tension, they do significantly affect the rheological properties of the interface. Above this ratio, free surfactant monomers and nanoparticle-surfactant complexes coexist and can co-adsorb at the interface, changing both the interfacial tension and the interfacial rheology, and thus, for example, the foamability and foam stability of the system.

Conventional electronics use the flow of electric charges and are based on standard semiconductors. Spintronic devices exploit the electrons’ spin to generate and control currents and to combine electric and magnetic signals. Today there is a strong effort worldwide to integrate spintronic devices with standard CMOS technology towards hybrid spin-CMOS chips, offering advantages in terms of power consumption, compactness, and speed. Recent results (from SAMSUNG [1], TSMC [2], etc.) confirm the merit of this approach.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit 225Ac wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht.[1,2] Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters 225Ac, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit 123I markieren zu können.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit Actinium-225 wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht. Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters Actinium-225, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit Iod-123 markieren zu können.
Ergebnisse: Durch die erfolgreiche Entwicklung einer Methode zur Iodierung der synthetisierten Zinnprecursoren mit hohen radiochemischen Ausbeuten konnten schließlich die einfach bzw. doppelt PSMA-gebundenen Verbindungen [¹²³I]I-mcp-M-alb-PSMA und [¹²³I]I-mcp-D-alb-PSMA hergestellt werden. Nach der Iodierung der Verbindungen wurde in vitro der Einfluss des ¹³⁹La-Komplexes als auch der des unkomplexierten Chelators an der PSMA-positiven Zelllinie LNCaP untersucht.
Schlussfolgerungen: Die Einführung von Iod-123 in die bereits untersuchten Derivate mit stabilem Iod-127 ergab keine Änderungen der biologischen Ergebnisse. Damit ergibt sich der neue Aspekt des theranostischen Nutzens als hybrides Radiopharmakon mit einer weiteren Markierungsstelle in der Peripherie des eigentlichen Liganden.