Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The martensitic microstructure decides on the functional properties of shape memory alloys. However, for the most commonly used alloy, NiTi, it is still unclear how its microstructure is built up because the analysis is hampered by grain boundaries of polycrystalline samples. Here, we eliminate grain boundaries by using epitaxially grown films in (111)B2 orientation. By combining scale-bridging microscopy with integral inverse pole figures, we solve the puzzle of the hierarchical martensitic microstructure. We identify two martensite clusters as building blocks and three kinds of twin boundaries. Nesting them at different length scales explains why habit plane variants with 〈011〉B19' twin boundaries and {942} habit planes are dominant; but also some incompatible interfaces occur. Though the observed hierarchical microstructure agrees with the phenomenological theory of martensite, the transformation path decides which microstructure forms. The combination of local and global measurements with theory allows solving the scale bridging 3D puzzle of the martensitic microstructure in NiTi exemplarily for epitaxial films.

Fredo Erxleben vom Helmholtz-Zentrum Dresden-Rossendorf erzählt uns, wie er und seine KollegInnen WissenschaftlerInnen, DoktorantInnen und Postdocs Programmieren beibringt. Der Bedarf an Training ist riesig. Der Bedarf an Ausbildern auch.
In dieser Folge schauen wir ein wenig hinter die Kulissen und Fredo erzählt welche Herausforderungen es bei den Trainingsprogrammen gibt.

Within the extension of the ΛCDM model, allowing for the presence of neutrinos or warm dark matter, we develop the analytical cosmological perturbation theory. It covers all spatial scales where the weak gravitational field regime represents a valid approximation. Discrete particles -- the sources of the inhomogeneous gravitational field -- may be relativistic. Similarly to the previously investigated case of nonrelativistic matter, the Yukawa interaction range is naturally incorporated into the first-order scalar metric corrections.

In this seminar talk, I will introduce applications of fragment molecular orbital method to study the interactions between protein and lanthanide/actinide.

The CFD modelling of annular flow is a challenge since it should take into account the continuous liquid film, the continuous gas core, and the dispersed droplets simultaneously. Recently, the CFD department in Helmholtz-Zentrum Dresden - Rossendorf (HZDR) are developing a morphology adaptive multifield two-fluid model that has great potential to simulate the three structures in a single computational domain. To complete the annular flow simulation in the morphology adaptive framework, a new droplet entrainment model is proposed in this work, which describes the mass transfer from the continuous liquid film to the dispersed droplets. The new entrainment model is developed based on the shear-off mechanism on the interfacial wave, implying that the entrainment behavior is dominated by the shear force and surface tension on the gas and liquid interface. Contrarily to previous entrainment models, the new model is correlated to the local flow parameters on the interface, so that it is suitable for the CFD framework. The properties of the new model are discussed and the model performance is verified by laboratory experiments. Qualitatively, the proposed model can simulate the generation of the interfacial wave from the inlet to the downstream. The droplets are mainly entrained at the front tip of the disturbance wave, where the shear force effect is remarkable. These phenomena are identical to the physical understanding of the droplet entrainment. Quantitatively, the characteristics of the droplet fraction matches the experimental results. The liquid film fraction obtained with the new model is analyzed and compared with the experiment. It turns out that the statistical parameters of film fraction's average value, standard deviation, possibility density function, and power spectral density match well with the experiment. Finally, the model comparisons show that the new model outperforms previous models with regard to droplet generation.

As an excellent demonstration of SRF gun technology, HZDR's SRF Gun-II has been rountinely operated as an electron gun for the ELBE THz radiation and the ELBE neutron source since 2018, delivering CW beams with bunch charges of up to 300 pC at 50-100 kHz.

As is well known, the quality of the photocathodes is crucial for the stability and reliability of the gun operation. Different cathodes have been used in the HZDR SRF gun and the cathodes have been replaced three to four times per year. In the last five years, the quality of the superconducting cavity has remained almost stable, but some characteristics of the gun have been observed related to the cathodes. In this contribution, we will introduce the operational aspect of the photocathodes in HZDR SRF gun, look back at the achievements and discuss open issues and possible improvements for future application.

Superconducting radio frequency photo injectors (SRF gun) offer advantages for operating in continuous wave (CW) mode and generating high-brightness and high-current beams. A new SRF gun is designed as a low emittance photo injector for LCLS-II-HE and a prototype gun is currently being developed under collaboration between SLAC, FRIB, HZDR and ANL. The aim is to demonstrate stable CW operation at a cathode gradient of 30 MV/m.
One of the crucial components for successful SRF gun operation is the photocathode system. The new SRF gun will adopt the HZDR-type cathode, which includes a cathode holder fixture (cathode stalk) developed by FRIB and a cathode exchange system designed by HZDR. This innovative cathode insertion system ensures accurate, particle-free and warm cathode exchanges. A novel alignment process targets the cathode to the stalk axis without touching cathode plug itself.
To commission the prototype gun, metallic cathodes will be used. A specifically designed vacuum system ensures vacuum pressure of 10-9 mbar for transport of a single cathode from the cleanroom to the gun.

The understanding of the contribution of the tumour microenvironment to cancer progression and metastasis, in particular the interplay between tumour cells, fibroblasts and the extracellular matrix has grown tremendously over the last years. Lysyl oxidases are increasingly recognised as key players in this context, in addition to their function as drivers of fibrotic diseases. These insights have considerably stimulated drug discovery efforts towards lysyl oxidases as targets over the last decade.
This review article summarises the biochemical and structural properties of theses enzymes. Their involvement in tumour progression and metastasis is highlighted from a biochemical point of view, taking into consideration both the extracellular and intracellular action of lysyl oxidases. More recently reported inhibitor compounds are discussed with an emphasis on their discovery, structure-activity relationships and the results of their biological characterisation. Molecular probes developed for imaging of lysyl oxidase activity are reviewed from the perspective of their detection principles, performance and biomedical applications.

The compositional, optical and structural stability of transparent conductive oxide SnO₂:Ta (1.25 at.% Ta) thin films at 650 °C and 800 °C in air was studied under isothermal conditions. After the high-temperature treatment, the element composition and the optical spectra of the material were unchanged. The X-ray diffraction confirmed the conservation of a single rutile-type phase. Two strong Raman lines located out of the SnO₂ phonon range indicated point defects in the material, which were identified as Sn vacancies and O interstitials by theoretical calculations. These point defects were partially healed out during the high-temperature treatment, without affecting the transmittance and reflectance of the material. Our study demonstrates an exceptional high in-air stability of Ta-doped SnO₂ and encourages it for applications in fields, where transparent conductive oxides with high-temperature and oxidation stability are required. These are, e.g., selective transmitters for concentrated solar power or electrodes for dye-sensitized solar cells and dynamic random-access memories.

Assuming nonnegligible relativistic component densities alongside the cold dark matter of the ΛCDM model, we reformulate cosmological perturbations within the framework of the cosmic screening approach. The scheme addresses all spatial scales, provided that gravitational interactions may be studied in the weak field limit to a good approximation. As a novel feature of the formulation, delta-shaped sources responsible for the inhomogeneous gravitational field are now allowed to be relativistic so that neutrinos or warm dark matter may also be incorporated into the extended model. Analytical expressions obtained for the first-order scalar potentials reveal that, like in the case of purely nonrelativistic matter studied previously, gravitational interactions of this wider class of components are also characterized by the time-dependent screening length, associated with the exponential cutoff introduced at large distances. (arXiv:2206.13495 [gr-qc])

Magnetic shape memory alloys offer a variety of multi-scale physical phenomena that can be exploited in actuation. Here we consider a NiMnGa Heusler alloy that has an austenitic structure at room temperature and investigate its small-scale mechanical response. With a particular interest in functional fatigue and potential dissipative processes, cyclic mechanical switching between the austenitic and martensitic phases is conducted with up to one million cycles in the pseudo-elastic range. We find that micron-sized NiMnGa crystals do essentially show no reduction in strain recovery as a function of cycling loading. This remains true for samples that purposely have been plastically pre-deformed, indicating a remarkable robustness against functional fatigue. Transmission electron microscopy complements our small-scale mechanical study. We discuss our findings in light of the microstructural evolution due to cyclic loading, and in comparison, to the material’s bulk behaviour.

NiMnGa shape-memory alloys are promising candidates for large strain actuation or magnetocaloric cooling devices. In view of potential small-scale applications, we probe here nanomechanically the stress-induced austenite-martensite transition in single crystalline austenitic thin films as a function of temperature. In 0.5 µm thin films, a marked incipient phase transformation to martensite is observed during nanoindentation, leaving behind pockets of residual martensite after unloading. These nanomechanical instabilities occur irrespective of deformation rate and temperature, are Weibull distributed, and reveal large spatial variations in transformation stress. In contrast, at a larger film thickness of 2 m fully reversible transformations occur, and mechanical loading remains entirely smooth. Ab-initio simulations demonstrate how an in-plane constraint can considerably increase the martensitic transformation stress, explaining the thickness-dependent nanomechanical behavior. These findings give insights into how reduced dimensions and constraints can lead to unexpectedly large transformation stresses in the studied shape-memory Heusler alloy.

Magnetic shape memory alloys exhibit various multifunctional properties, which range from high stroke actuation and magnetocaloric refrigeration to thermomagnetic energy harvesting. Most of these applications benefit from miniaturization and a single crystalline state. Epitaxial film growth is so far only possible on some oxidic substrates, but they are expensive and incompatible with standard microsystem technologies. Here, we demonstrate epitaxial growth of Ni-Mn-based Heusler alloys with single crystal-like properties on silicon substrates by using a SrTiO3 buffer. We show that this allows using standard microfabrication technologies to prepare partly freestanding patterns. Our approach is versatile, as we demonstrate its applicability for the NiTi shape memory alloy and discuss for spintronic and thermoelectric Heusler alloys. This paves the way for integrating additional multifunctional effects into state-of-the-art microelectronic and micromechanical technology, which is based on silicon.

Gravitational clustering of cold dark matter, as predicted by concordance cosmology, is often studied via N-body simulations based on Newtonian dynamics. Though efficient in tracking nonlinear growth of fluctuations at small scales, outcomes of such simulations cannot be linked to observables immediately, and a certain effort is required to obtain relativistic interpretations of variables by employing convenient gauges and dictionaries. Based on a weak-field expansion of general relativity, a fully-relativistic N-body code has been introduced in the past decade (Adamek, J., Daverio, D., Durrer, R., Kunz, M., JCAP 07, 053 (2016)), capable of evolving all metric variables in the Poisson gauge which is the conventional choice in formulating cosmological perturbations. However, spatial and temporal derivates are assigned different orders of smallness and field equations, containing admixtures of higher-order terms, acquire a rather complex form. In this talk we will explore an alternative formulation of perturbations, still based on a weak-field expansion, and expressed in the Poisson gauge, which however treats all derivates on equal footing and hence a clear distinction exists between first and second order contributions in the expansion (Eingorn, M., ApJ 825, 84 (2016), Canay, E., Eingorn, M., PDU 29, 100565 (2020), arXiv:2206.13495 [gr-qc]). We will show that it is possible to obtain analytical solutions for the scalar and vector potentials in this scheme and that they hint at some exciting characteristics of gravitational interactions at large-enough cosmological scales.

We describe multi-quark clusters in quark matter within a Beth-Uhlenbeck approach in a background gluon field coupled to the underlying chiral quark dynamics using the Polyakov gauge. An effective potential for the traced Polyakov loop is used to establish the property of color SU(3) center symmetry as an aspect of confinement.
A higher multi-quark cluster of size $a$ is described as a binary composite of smaller subclusters a1 and a2 (where a1+a2=a) with a bound state and a scattering state spectrum. For the corresponding cluster-cluster phase shifts we use simple ansätze that capture the Mott dissociation of clusters as a function of temperature and chemical potential. We compare the simple "step-up-step-down" model that ignores continuum correlations with an improved model that includes them in a generic form.
In order to explain the model, we restrict ourselves here to the cases where the largest cluster contains six quarks.
One striking result is the suppression of the abundance of colored multi-quark clusters at low temperatures by the coupling to the Polyakov loop. This is understood in close analogy to the suppression of free quark abundances by the same mechanism. We derive here the corresponding Polyakov-generalized distribution functions of b -quark clusters. Another new result is the effective suppression of free quarks by a large (> 600 MeV) constituent quark mass generated by dynamical breaking of the approximate chiral symmetry in the quark sector and its sudden restoration at the Mott temperature, where all hadronic bound states become dissociated into the multi-quark continuum.
Within our approach we calculate thermodynamic properties such as baryon density and entropy. A comparison with lattice calculations shows that our model is able to give a unified, systematic approach to describe properties of the quark-gluon-hadron system.

This is a talk for students of RTG 2767 “Supracolloidal structures” running at the TUD. I will discuss current developments in magnetic composite-based actuators and sensor devices.

Density functional methods have been successfully applied to describe properties of atomic nuclei and infinite nuclear matter. A particularly successful approach for applications in simulations of neutron stars, their mergers and supernova explosions is the relativistic mean field theory with density dependent couplings (DD2). For densities exceeding twice the nuclear saturation density, i.e. for neutron stars heavier than about 1.4 solar masses, the excitation of hyperons and heavy baryons leads to a softening of the nuclear equation of state and a limitation of the maximum neutron star mass to about 2 solar masses (“Berlin wall” constraint, formerly known as the hyperon puzzle), a tension with recent mass measurements.
I will review recent progress to overcome the Berlin wall constraint with quark deconfinement in neutron star interiors, where the dense quark matter equation of state is obtained from a relativistic density functional approach that allows to model quark confinement at low densities as well as color superconductivity and the transition to the conformal symmetric phase at high densities.
On the basis of this new density functional approach to quark matter a supernova explosion mechanism for massive blue supergiant stars has been suggested and a signal of quark deconfinement in the pattern of gravitational waves from binary neutron star mergers.
I shall give an outlook to the development of a unified description of quark-nuclear matter in the form of a density functional approach.

The cosmogenic radionuclide 10Be is used for a variety of applications, its analysis however requires laborious purification methods. We developed a simple purification protocol for Be from sediment samples that works without strongly hazardous chemicals or time consuming and expensive ion exchange columns. The combination of hydroxide precipitations and precipitation in NaHCO3 was compared to an established protocol of hydroxide precipitations and ion exchange columns. The new method has a slightly lower Be-yield and purity of the resulting samples. However, this does not have a significant influence on performance during AMS-measurement where both methods performed equally well. The avoidance of column chromatography reduces sample preparation costs and space requirements in the lab allowing for more samples to be prepared simultaneously.

T-cells genetically modified to express chimeric antigen receptors (CARs) are playing a more and more
important role in targeted cancer immunotherapy. However, these living drugs can also cause lifethreatening
side effects. To overcome such limitations and improve the safety of CAR T-cell therapy,
adaptor CAR platforms such as the universal CAR (UniCAR) have been developed. This platform consists
of the UniCAR T-cell and a target module (TM) cross-linkage effector and tumor cells. Here, we have
established a novel UniCAR system targeting Fibroblast Activation Protein (FAP) that is highly expressed
in the tumor microenvironment of epithelial cancers and a marker for cancer-associated fibroblasts. For
that, we constructed two novel FAP-directed TMs possessing different sizes and pharmacokinetic
properties, in which one is based on a single-chain variable fragment (scFv), and the other is based on an
IgG4 backbone. We have shown that both TMs were able to bind to FAP-expressing cells and redirect
UniCAR T-cells in vitro to monolayer and spheroid target cells inducing effective killing. Furthermore, we
could show infiltration and activation of T-cells in the spheroid setting. Using in vivo models, the TMs were
proven to be suitable to be used for PET imaging showing FAP-specific accumulation at the tumor site.
Moreover, the immunotherapeutic effect of UniCAR T-cells in combination with FAP TMs was
demonstrated using mouse models. In conclusion, in this work, we could show that the two novel anti-
FAP TMs prove to hold great theranostic potential for diagnostic imaging and immunotherapy.

Immunotherapy based on chimeric antigen receptor (CAR) T-cells has demonstrated remarkable therapeutic effects, particularly against some hematological cancers. A versatile adaptor CAR system called RevCAR, consisting of RevCAR T-cells and a bispecific target module (RevTM) has been developed to overcome severe side effects associated with conventional CAR T-cell therapy. As the activity of RevCAR T-cells can be steered based on the availability of RevTM, working as an on/off switch, the system can be immediately turned off if side effects occur. Furthermore, the RevCAR system is highly flexible, since the same RevCAR T-cell can be directed towards different tumor-associated antigens (TAA) simply by adding RevTMs with different specificities. However, the effectiveness of CAR T-cells against solid tumors remains limited particularly due to their immunosuppressive tumor microenvironment (TME). To overcome these hurdles, we have established a novel RevCAR system targeting immune checkpoint molecules such as PD-L1, which are frequently overexpressed by cancer cells to suppress immune responses. We have constructed novel RevTMs that can redirect RevCAR T-cells to kill tumor cells that express such immune checkpoint molecules. Furthermore, true AND gate tumor targeting was achieved by targeting a TAA in addition to PD-L1 in a combinatorial manner using our Dual-RevCAR system. In this way, targeting PD-L1 not only results in Dual-RevCAR T-cell activation but simultaneously blocks the immunosuppressive PD-L1/PD-1 axis. Altogether, we have turned an immunosuppressive marker into an immune-activating signal that might modulate the TME in a beneficial manner, showing promise for the development of an effective immunotherapy against solid tumors.

Engineered T cells that express chimeric antigen receptors (CARs) show a big potential in cancer immunological research. They are synthetic receptors that can target antigens independently from the MHC complex. However, most tumor associated antigens are not only expressed on the tumor site but also on healthy tissues. To switch off CAR T cells in case of on-target/off-tumor effects occur, an adaptor CAR platform, called the universal CAR (UniCAR), was developed. In contrast to conventional CAR systems this platform consists of the engineered T cells and a linker molecule, called target module (TM), that is both binding to the target antigen and recognized by the UniCAR T cell. With this approach there is the possibility to switch the system on and off when needed.
Fibroblast activation protein (FAP) is a protein of high interest in cancer research as it is upregulated in most of epithelial cancers but shows a comparably low expression in healthy tissues. It is shown to be expressed on cancer associated fibroblasts and therefore plays an important role in the tumor microenvironment where it has pro-tumorigenic activity both in the FAP positive and surrounding cells. Given this, the goal of this work was to develop new TMs against FAP.
To achieve such aim, we cloned two TM formats, either based on a single-chain variable fragment (scFv) or an IgG4 based backbone. The difference in the size of the backbones translates into different half-lifes and kinetics. These different TM formats can be used to customize UniCAR therapy according to the given circumstances. We were able to purify and perform various experiments with the mentioned TMs. We could show binding to the target cells using flow cytometry. We could also show that the TMs could be used to induce specific lysis in vitro on monolayer cells and spheroids. We were also able to show UniCAR T cell infiltration into the spheroids and their consequent activation. Moreover, in mouse models the TMs could be used for PET imaging, showing specific accumulation at FAP-expressing tumor cells, as well as for killing of such tumors using redirected UniCAR T cells.
By that we could show that the anti-FAP scFv and IgG4 based TMs have high theragnostic potential as they can be used for both immunotherapy and diagnostic imaging.

The recent flourishing of research on non-aqueous actinide coordination chemistry has facilitated a deeper understanding of actinide metal-ligand interactions. In particular, studies utilizing ligands with soft donor atoms (N, S) have highlighted the subtle chemical differences between trivalent actinide (An) and lanthanide (Ln) ions. They provide not only theoretical and experimental insights but also the foundation for practical applications e.g. minor actinides separation. As part of our efforts to elucidate these differences, typically attributed to an increased covalency in the actinide compounds, we conducted research using N,N’-diisopropylbenzamidinate (iPr2BA) as a model N-donor ligand.

In this work, a series of trivalent lanthanide (La, Nd, Sm, Eu) and actinide (U, Np) tris-iPr2BA complexes [M(iPr2BA)3] were successfully synthesized and characterized in solid state to gain a comprehensive understanding of the bonding situation between f-block elements and N-donor ligands. Intensive paramagnetic NMR studies in solution have been carried out and the Bleaney method was applied to separate hyperfine shift contributions (Fermi contact and Pseudocontact contributions). Furthermore, quantum chemical calculations have been performed in order to evaluate the intramolecular bonding trends and electronic structures.

ACKNOWLEDGEMENT
This study was supported by the German Federal Ministry of Education and Research (BMBF) under the project No. 02NUK059B (f-Char).

Although the chemistry of uranium alkoxides has been widely studied, not much attention has been paid to alkoxide chemistry of transuranic elements. In 1967, Samulski and Karraker were able to isolate a few examples of transuranic alkoxides. However, these complexes were only characterized using elemental analysis and absorption spectra. These compounds were never structurally characterized.
Based on recent achievements in synthesizing novel transuranic starting materials, we were able to isolate four mono- and bimetallic tert-butoxides with Np(IV). [Np₃O(OtBu)₁₀] and [K₄Np₂O(OtBu)₁₀] were synthesized using the ligand substitution between neptunium(IV) silylamides and HOtBu, whereas the salt metathesis between [NpCl₄(DME)₂] (DME = dimethoxyethane) and various amounts of LiOtBu resulted in the formation of the oxo-free alkoxides [Np(OtBu)₄(py)₂] (py = pyridine) and [Li(THF)]₂[Np(OtBu)₆]. To the best of our knowledge, these compounds represent the first structurally characterized Np(IV) alkoxides using single crystal X-ray diffraction and solid-state UV-vis-NIR spectroscopy. Furthermore, treatment of [Np(OtBu)₄(py)₂] with [Fe(OtBu)₃]₂ results in the formation of a heterobimetallic complex [NpFe(OtBu)₇(py)]. A solvent dependent coordination motif on both metal sides was observed, leading to the formation of [NpFe(OtBu)₇].

Actinides (An) play an important role in chemical engineering and environmental science related to the nuclear industry or nuclear waste disposal. In contrast to the strongly shielded 4f electrons of the lanthanides, 5f electrons of particularly the early An are found to participate in bonding, e.g. to organic ligands. Another characteristic of the An is their huge variety of possible oxidation states, typically ranging from +II to +VII for early actinides, making their chemistry complex but interesting.
A suitable approach to explore fundamental physico-chemical properties of the actinides is to study series of isostructural An compounds in which the An is in the same oxidation state. Observed changes in e.g. the binding situation or magnetic effects among the An series may deliver insight into their unique electronic properties mainly originating from the f electrons. A question still remaining in the field of An chemistry is the degree of “covalency” in compounds across the actinide series, which may be addressed by systematic studies on series of An compounds, including transuranium elements.
We investigate the coordination chemistry of low-valent actinides using organic N-, O-, and S-donor ligands. Information on trends in covalency as well as mutual ligand influences can be obtained by the analysis of solid-state structures derived by SC-XRD in combination with quantum chemical calculations. Additional insight can be gained from high-energy-resolution fluorescence detection X-ray absorption near edge spectroscopy. In solution, NMR spectroscopy permits to draw conclusions about the complex speciation in solution, the intrinsic magnetic properties of the actinides, or subtle changes in covalency in the ligand-actinide bonding.

Often the bulk properties of materials like the lattice constant (interparticle distance and/or separation), stress tensor, etc., at high pressures and temperatures differ significantly from those under ambient conditions. The situation is particularly unsatisfactory for warm dense matter (WDM), where basic atomic properties like an atomization energy become ill defined and where bulk properties such as bulk moduli cannot be accurately measured due to extreme conditions. This calls for an approach that allows the non-empirical choice of the parameters of hybrid functionals without employing properties limited to ambient conditions. At the same time, it is preferable that such an approach have some connection to properties that are well defined and measurable in experiments across temperature and pressure regimes. We report that the static XC kernel can serve as a theoretical device for constructing hybrid functionals that are non-empirical and that apply for both solid-state systems and WDM [1-3].

[1] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, and Tobias Dornheim, Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel, The Journal of Physical Chemistry Letters 14, 1326–1333 (2023), https://doi.org/10.1021/acs.jpclett.2c03670

[2] Zhandos Moldabekov, Maximilian Boeme, Jan Vorberger, David Blaschke, and Tobias Dornheim, Ab initio Static Exchange-Correlation Kernel across Jacob’s Ladder without functional derivatives, Journal of Chemical Theory and Computation 19, 1286–1299 (2023), https://doi.org/10.1021/acs.jctc.2c01180

[3] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, Tobias Dornheim, Assessing the accuracy of hybrid exchange-correlation functionals for the density response of warm dense electrons, J. Chem. Phys. 158, 094105 (2023)
https://doi.org/10.1063/5.0135729

Invited talk at CLFV23 conference, June 20 - 23, 2023.

We presetnt a method to compute a static exchange-correlation (XC) kernel across temperature regimes using KS-DFT for any XC functional available in Libxc [1]. We show the results of the static exchange-correlation kernel analysis using various XC functionals for dense electron gas and warm dense hydrogen. The results allow to better understund the effect of thermal excitations and density inhomogeneity on the XC kernel. Based on a comparison of KS-DFT data with high-precision Quantum Monte Carlo (QMC) data for both high temperatures and the ground state, we present the results of the analysis of the accuracy of the commonly used XC functionals for warm dense matter simulations [1-4]. As an application of the static XC kernel, we discuss linear-response time-dependent density functional theory (TDDFT) approach to warm dense matter with adiabatic exchange--correlation kernels [5].

The exchange correlation kernel (XC) naturally arises within the framework of linear response theory as a key quantity for describing correlated systems of many particles. Particularly, the XC kernel is needed in linear response TDDFT (LR-TDDFT), which is a powerful ab initio method that
allows one to describe dynamical and transport properties of equilibrium quantum-many body systems. A standard approach of the calculation of the XC kernel in LR-TDDFT is based on the computation of the second order functional derivative of a XC functional with respect to density. For extended systems, this approach is limited to simple static (adiabatic) LDA and GGA (such as PBE ) level XC functionals due to mathematical and computational challenges of computing functional derivatives of meta-GGA and hybrid level functionals. In fact, only adiabatic LDA (ALDA) is available in commonly used open source DFT codes. We have overcome these limitations by developing a new method of the calculation of the XC kernel [1], which utilizes the method of a direct harmonic perturbation. The essence of the developed approach is to compute a static density response function of a system by measuring the density perturbation induced by an external static harmonic field; with density being extracted from an equilibrium KS-DFT simulation. An alternative and equivalent definition of the XC kernel as a difference between the inverse values of the density response functions of systems with non-zero and zero XC functionals allows us to access the XC kernel without explicitly computing functional derivatives. This allows one to compute the XC kernel using available XC functionals through the ranks of Jacob's ladder and for any temperature. We demonstrated the utility of this method by analyzing the XC kernel beyond GGA level including meta-GGA and hybrid XC functionals [1-3]. In addition, we have presented a workflow for using the static XC kernel from the direct perturbation approach in the
LR-TDDFT of warm dense matter [4].

[1] Zhandos Moldabekov, Maximilian Böhme, Jan Vorberger, David Blaschke, and Tobias
Dornheim, Ab Initio Static Exchange–Correlation Kernel across Jacob’s Ladder without Functional
Derivatives, Journal of Chemical Theory and Computation 19 (4), 1286-1299 (2023 )
[2] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, Tobias Dornheim,
Assessing the accuracy of hybrid exchange-correlation functionals for the density response of warm
dense electrons. J. Chem. Phys. 158 (9), 094105 (2023).
[3] Zhandos A. Moldabekov, Mani Lokamani, Jan Vorberger, Attila Cangi, and Tobias Dornheim,
Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel, The
Journal of Physical Chemistry Letters 14 (5), 1326-1333 (2023)
[4] Zhandos A. Moldabekov, Michele Pavanello, Maximilian P. Böhme, Jan Vorberger, and Tobias
Dornheim, Linear-response time-dependent density functional theory approach to warm dense
matter with adiabatic exchange-correlation kernels, Phys. Rev. Research 5, 023089 (2023)

To improve postoperative monitoring of patients undergoing pancreatic surgery, we propose a bedside, droplet-based millifluidic device that facilitates near real-time accurate and rapid determination of drain amylase activity. Drain liquid is co-encapsulated with a starch substrate in multiple nanoliter-sized reactors to track the fluorescence intensity released upon reaction with amylase. Comparing the amylase levels of 32 patient samples, 31 out of 32 millifluidic system results (96.9%) matched the clinical data within the 95% confidence interval. Importantly, the new millifluidic strategy significantly reduces the amylase assay time from several hours to approximately 3-4 minutes and offers a ca. 10 times lower limit of detection of 0.007 µmol/sL compared to that of current clinical techniques. Finally, we for the first time demonstrate the possibility of dynamic monitoring of amylase levels in the patient samples. Thus, the proposed droplet-based instant assay system could augment state-of-the-art clinical methods and significantly improve diagnosis of postoperative complications in patients after pancreatic surgery via near-real-time bedside monitoring.

Oncology research has been an exciting area for the application of electrical biosensors over the last few decades. Extremely high sensitivity of field-effect transistor-based (FET) biosensors directed the interest of scientists mostly to early cancer detection applications. However, the potential of electrical biosensors should not be limited to cancer diagnosis. With immunotherapy on the way to become the fourth pillar of cancer treatment, there will be an increasing demand for immunoassay testing before, during, and after the conduction of therapeutic treatment. Our previous results have demonstrated the usefulness of FET-based biosensors in the research and development of a safer engineered chimeric antigen receptor (CAR) T-cells-based therapy. In this work, we continue to explore the practicality of electrical biosensors in the potential therapeutic setting of immunotherapy. Here, we present a complete stand-alone FET-based biosensing system relying on the extended gate (EG) concept. Our platform has an independent readout which is portable, compatible with multiplexed measurement, and self-sufficient for point-of-care sensing purposes. The extended gate sensing chip is disposable and can be tailored for the specific sensing application. Compared to the traditional ion-sensitive FET setup, EG FET provides improved flexibility, cost-effectiveness, and adaptiveness to individual needs making it a promising candidate for clinical application. During a universal CAR T-cells (UniCAR) therapy, “switch” molecules are injected into the patient’s bloodstream to activate the T-cell processes for attacking tumors. Therefore, it is crucial to monitor the level of CAR T-cells and switch molecules for better control and decision-making related to personalized treatment. Here, we demonstrate the application of our EG FET platform in testing the therapeutic components of this treatment and discuss the related outlook for FET-based biosensors in immunotherapy. Our work endeavors to bridge the gap between clinical needs in immunotherapy and available sensing technology by broadening the application area for electrical biosensors.

Microorganisms show a high affinity for trivalent actinides and lanthanides, which play an important role in the safe disposal of high-level radioactive waste as well as in the mining of various rare earth elements. The interaction of the lanthanide Eu(III) with the sulfate-reducing microorganism Desulfosporosinus hippei DSM 8344T, a representative of the genus Desulfosporosinus that naturally occurs in clay rock and bentonite, was in-vestigated. Eu(III) is often used as a non-radioactive analogue for the trivalent actinides Pu(III), Am(III), and Cm(III), which contribute to a major part of the radiotoxicity of the nuclear waste. D. hippei DSM 8344T showed a weak interaction with Eu(III), most likely due to a complexation with lactate in artificial Opalinus Clay pore water. Hence, a low removal of the lanthanide from the supernatant was observed. Scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed a bioprecipitation of Eu(III) with phosphates potentially excreted from the cells. This demonstrates that the ongoing interaction mechanisms are more complex than a sim-ple biosorption process. The bioprecipitation was also verified by luminescence spec-troscopy, which showed that the formation of the Eu(III) phosphate compounds starts almost immediately after the addition of the cells. Moreover, chemical microscopy pro-vided information on the local distribution of the different Eu(III) species in the formed cell aggregates. These results provide first insights into the interaction mechanisms of Eu(III) with sulfate-reducing bacteria and contribute to a comprehensive safety concept for a high-level radioactive waste repository, as well as to a better understanding of the fate of heavy metals (especially rare earth elements) in the environment.

From microplastics resuspending into the atmosphere to earth particles left behind during extraterrestrial explorations, the resuspension of microparticles by a turbulent gas flow occurs in many natural and industrial systems. Wall surfaces, onto which particles initially adhere, are rarely smooth and this surface roughness affects their resuspension. Available experimental data on particle resuspension have been obtained with substrates, whose surfaces are either unaltered or manually abraded with, for instance, sand blasting. In these experiments, the roughness elements span a wide size range and are in-homogeneously distributed in space. Surface functionalization is a modern technique allowing the precise fabrication of a wall surface with well-characterized microstructures, hence reducing the asperity randomness associated with conventional abrasion techniques. Taking advantage of surface functionalization, we present here a new set of reference data, where the wall asperities are represented by a structured arrangement of micropillars and microcubes. Adhesion force measurements and particle remaining fraction against gas velocity, at Reynolds number up to 8000, are reported for one reference and two artificially roughened substrates. Laboratory measurements show that the microasperities have little to moderate effect on the mean adhesion force and the threshold velocity, at which half of the 100-µm particles resuspend. The standard deviations are, however, significantly affected. The presented results will primary contribute to the improvement of resuspension models, which until now rely on a simplified representation of the surface roughness elements. The presented measurements are highly compatible with such models, which involve elementary roughness features, such as hemispherical asperities superimposed with a flat plate.

We study the meson contribution to the equation of state of the 2-flavor Polyakov-loop Nambu–Jona-Lasinio model, including the full momentum dependence of the meson polarization loops. Within the Beth-Uhlenbeck approach, we demonstrate that the contribution from the quark-antiquark continuum excitations in the spacelike region ω^2 − q^2 < 0, i.e., the Landau damping, leads to an increase of the pressure for temperatures ≳0.8T^χ_c and a significant meson momentum cutoff dependence in the mesonic pressure and the QCD trace anomaly. We investigate the dependence of the results on the choice of the Polyakov-loop potential parameter T_0. From the dependence of the mesonic pressure on the current quark mass, by means of the Feynman-Hellmann theorem, we evaluate the contribution of the pion quasiparticle
gas and Landau damping to the chiral condensate.

We utilize pump-probe spectroscopy to measure the quasiparticle relaxation dynamics of BaFe2As2 in a diamond anvil cell at pressures up to 4.4 GPa and temperatures down to 8 K. Tracing the amplitude of the relaxation process results in an electronic phase diagram that illustrates the variation of the spin-density wave (SDW) order across the whole range of the applied pressures and temperatures. We observe a slowing down of the SDW relaxation dynamics in the vicinity of the phase transition boundary. However, its character depends on the trajectory in the phase diagram: the slowing down occurs gradually for the pressure-induced transition at low temperatures and abruptly for the thermally-driven transition. Our results suggest that the pressure-induced quantum phase transition in BaFe2As2 is related to the gradual worsening of the Fermi-surface nesting conditions.

To date, perfusion simulations in the human brain have been limited to a relatively small number of patient-specific cases. Here, a
pipeline relying on magnetic resonance imaging (MRI) is proposed to overcome this limitation. The computational geometry is
adjusted using T1-weighted MRI, whereas the perfusion model parameters are tuned based on arterial spin labeling perfusion MRI. A
cohort of 75 patients is considered to demonstrate that the pipeline is suitable to generate virtual patients with statistically realistic
cerebral blood flow maps. In the future, in silico clinical trials will be conducted using similar virtual cohorts to improve ischaemic
stroke interventions.

We demonstrate a significantly simplified experimental approach for investigating liquid metallic hydrogen, which is crucial to
understand the internal structure and evolution of giant planets. Plastic samples were shockcompressed and then probed by
short pulses of X-rays generated by free electron lasers. By comparison with ab initio simulations, we provide indirect
evidence for the creation of elemental hydrogen in shock-compressed plastics at ∼150GPa and ∼5,000K and thus in a
regime where hydrogen is predicted to be metallic. Being the most common form of condensed matter in our solar system,
and ostensibly the simplest of all elements, hydrogen is the model case for many theoretical studies and we provide a new
possibility to benchmark models for conditions with extreme pressures and temperatures. Moreover, this approach will also
allow to probe the chemical behavior of metallic hydrogen in mixture with other elements, which, besides its importance for
planetary physics, may open up promising pathways for the synthesis of new materials.

Actinides (An) play an important role in chemical research and environmental science related to the nuclear industry or nuclear waste repositories. Investigating their coordination chemistry can function as a tool to obtain fundamental understanding of actinide binding. Due to the radiotoxicity of actinide complexes, special care in handling those material is needed in form of working in a controlled area lab. Therefore, the understanding of complexation properties of the actinides, in particular the transuranium (TRU) elements, is lacking behind those of the d- or 4f-elements.
For the early actinides possible oxidation states typically range from +II to +VII. A suitable approach to explore fundamental physico-chemical properties of the actinides is to study series of isostructural An compounds in which the An is in the same oxidation state. Therefore, our investigations are directed towards the synthesis of actinide complexes (An = Th, U, Np, and Pu) with the f-element in the oxidation state IV, the dominant oxidation state particularly under anoxic conditions. Observed changes in e.g. the binding situation or magnetic effects along such series deliver insight into the elements’ unique electronic properties mainly originating from the f-electrons. One important question in the field of An chemistry is the degree of “covalency” in compounds across the An series, which may be addressed by systematic studies on series of An compounds, including transuranium (TRU) elements.
An complexes using ambidentate ligand systems can give valuable information on covalency differences between soft and hard donor atoms in one complex system. We therefore chose the 2-mercaptopyridyl ligand system (PyS) as monoanionic ambidentate S,N-moiety. Due to possible resonance structures in the ligand backbone, the negative charge can be distributed over both donor atoms. This leaves sufficient flexibility for PyS to coordinate to the actinide atom in a S- or N-monodentate or S,N-chelating manner. We synthesized a series of PyS-containing Th, U, Np, and Pu complexes and compare their structural and spectroscopic characteristics along the early actinides. These results are used as a basis to further analyze bonding trends along the actinide series by means of quantum chemical calculations.
From the results, trendlines along the actinides were obtained, which shed some light in the ongoing debate of covalency in actinide bonding.

https://u.ganil-spiral2.eu/10.26143/GANIL-2016-E710.html

Im Zusammenspiel magnetischer und elektrischer Felder entstehen
elektromagnetische Kräfte. Deren praktische Anwendung z. B. in Elektromotoren ist aus unserem Alltag nicht mehr wegzudenken.
Elektromagnetische Kräfte sind aber auch in der Lage, leitfähige Flüssigkeiten, wie Elektrolyte und Metallschmelzen, kontaktlos zu beeinflussen.
Die Vielfalt an Strömungskonfigurationen, die mit einfachen Permanentmagneten in einer Elektrolysezelle einstellbar sind, wird im Experiment
demonstriert.

Energie ist auf vielfltige Weise mit dem Leben verknüpft. Im Laufe der Geschichte dominierten unterschiedliche Energieträger. Der Vortrag nimmt sie unter die Lupe und zeigt den Wandel ihrer Nutzung und die damit verbundenen Konsequenzen. Ein Schwerpunkt ist die im Horizon 2020 Projekt SOLSTICE entwickelte Speichertechnologie.

Die geplante Umstellung des Energiesystems auf fluktuierende Erzeuger zieht einen immensen Bedarf an Speichern nach sich, um Angebot und Nachfrage auszugleichen. Der Vortrag stellt verschiedene Arten von Flüssigmetallbatterien vor, die derzeit mit dem Ziel einer ökonomischen stationären Energiespeicherung entwickelt werden.

Die geplante Umstellung des Energiesystems auf fluktuierende Erzeuger zieht einen immensen Bedarf an Speichern nach sich, um Angebot und Nachfrage auszugleichen. Der Vortrag stellt verschiedene Arten von Flüssigmetallbatterien vor, die derzeit mit dem Ziel einer ökonomischen stationären Energiespeicherung entwickelt werden.

The aim of the PANAS project, sponsored by the German Federal Ministry of Education and Research, was an in-depth analysis of the energy transfer processes of condensation and evaporation in inclined pipes at high and low system pressures, as they are used in passive residual heat removal systems for GEN III/III+ nuclear power plants. Passive residual heat removal systems play an important role in controlling accidents in the design basis, but also in beyond design basis accidents. By application of innovative measurement technologies, it was possible to study condensation and evaporation processes with an unprecedented temporal and spatial resolution, providing a new and unique database for further development and validation of CFD and system codes. With the work carried out in the project the experimental database was significantly expanded and an important contribution was made to provide sufficiently validated numerical tools, which allow authorities and experts to evaluate new reactor concepts and nuclear power plants with passive
residual heat removal systems.
Based on a series of COSMEA tests conducted in 2020 and 2021, the paper presents results of post-test simulations performed with a standard version of ATHLET as well as with an improved version of the code. After an overview on the research topics, the paper discusses the heat transfer phenomena in an emergency condenser pipe, the corresponding physical models implemented in ATHLET and the input deck developed to simulate the COSMEA tests. First results of the simulations with the standard version of ATHLET showed a significant underestimation of the transferred heat flow, an overestimation of the condensate outlet temperature and, depending on the experimental conditions, an underestimation or overestimation of the condensation rate. An in-depth analysis of the results helps to identify possible reasons for the deviations. The second set of simulations with an improved version of the code shows much better agreement with the experimental data. The corresponding part of the paper describes the modifications to the source code, the physical reasons behind these modifications and the improvements obtained with the updated models.

Classical novae are thermonuclear explosions in stellar binary sys- tems, and important sources of 26Al and 22Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowl- edge of its nucleosynthesis. The 22Na(p,γ)23Mg reaction remains the only source of large uncertainty about the amount of 22Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in 23Mg. Here, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this method to the study of the 23Mg states, places strong limits on the amount of 22Na produced in novae and constrains its detectability with future space-borne observatories.

Radionuclide therapies are an important tool for the management of patients with neuroendocrine tumors (NETs). Especially [131I]MIBG and [177Lu]Lu-DOTA-TATE are routinely used for the treatment of a subset of NETs, including phechromocytomas, paragangliomas and gastroenteropancreatic tumors. Some patients suffering from other forms of NETs, such as medullary thyroid carcinoma or neuroblastoma, were shown to respond to radionuclide therapy; however, no general recommendations exist. Although [131I]MIBG and [177Lu]Lu-DOTA-TATE can delay disease progression and improve quality of life, complete remissions are achieved rarely. Hence, better individually tailored combination regimes are required. This review summarizes currently applied radionuclide therapies in the context of NETs and informs about recent advances in the development of theranostic agents that might enable targeting subgroups of NETs that previously did not respond to [131I]MIBG or [177Lu]Lu-DOTA-TATE. Moreover, molecular pathways involved in NET tumorigenesis and progression that mediate features of radioresistance and are particularly related to the stemness of cancer cells are discussed. Pharmacological inhibition of such pathways might result in radiosensitization or general complementary antitumor effects in patients with certain genetic, transcriptomic, or metabolic characteristics. Finally, we provide an overview of approved targeted agents that might be beneficial in combination with radionuclide therapies in the context of a personalized molecular profiling approach.

In our HELIPORT workshop, we provided insights into our project and share our results. In addition, we would like to provide a platform for the presentation of similar projects, as well as extensions or integrations from the surrounding research areas. The overall goal of the workshop is bringing together different institutions with similar challenges and establishing a community around our HELIPORT project.
We therefore encouraged our community to submit an abstract for a talk or poster. The submissions are dedicated to four thematic points:

• HELIPORTuse-cases,
• Scientificprojectandmetadatamanagement, • Experiment-specificandoverallmetadataand • Scientificworkflows.

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)

In this talk, I will present our research on the application of time-dependent density functional theory (TDDFT) to model observables induced in matter under extreme conditions. Specifically, I will discuss the electron loss function in scattering experiments with X-ray free electron lasers [1] and the electrical conductivity in metals [2, 3]. Additionally, I will explore the potential of physics-informed neural networks for solving the time-dependent Kohn-Sham equations, which describe electron dynamics in response to incident electromagnetic waves [4].

[1] Z. Moldabekov, T. Dornheim, A. Cangi, Sci. Rep. 12, 1093 (2022).
[2] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, Phys. Rev. B 107, 115131 (2023).
[3] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, arXiv:2210.10132 (2022).
[4] K. Shah, P. Stiller, N. Hoffmann, A. Cangi, NeurIPS Machine Learning and the Physical Sciences, arXiv:2210.12522 (2022).

In this talk, I will present two lines of our research. In the first part, I will discuss the application of time-dependent density functional theory (TDDFT) in modeling observables induced in matter under extreme conditions, such as the electron loss function relevant to scattering experiments with X-ray free electron lasers [1] and the electrical conductivity in metals [2]. In the second part, I will highlight our recent progress in leveraging Artificial Intelligence (AI) to enhance the efficiency of electronic structure calculations [3]. Specifically, I will focus on our efforts to accelerate Kohn-Sham density functional theory calculations at finite temperatures by integrating deep neural networks into the Materials Learning Algorithms framework [4,5]. Our results demonstrate significant improvements in calculation speed for metals up to their melting point. Additionally, our implementation of automated machine learning has led to substantial savings in computational resources for identifying optimal neural network architectures, paving the way for large-scale AI-driven investigations [6]. Lastly, I will present our latest breakthrough, showcasing the capability of neural-network-driven electronic structure calculations for systems containing over 100,000 atoms [7].

[1] Z. Moldabekov, T. Dornheim, A. Cangi, Sci. Rep. 12, 1093 (2022).
[2] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, Phys. Rev. B 107, 115131 (2023).
[3] L. Fiedler, K. Shah, M. Bussmann, A. Cangi, Phys. Rev. Materials 6, 040301, (2022).
[4] A. Cangi, J. A. Ellis, L. Fiedler, D. Kotik, N. A. Modine, V. Oles, G. A. Popoola, S. Rajamanickam, S. Schmerler, J. A. Stephens, A. P. Thompson, MALA, https://doi.org/10.5281/zenodo.5557254 (2021).
[5] J. A. Ellis, L. Fiedler, G. A. Popoola, N. A. Modine, J. A. Stephens, A. P. Thompson, A. Cangi, Phys. Rev. B 104, 035120 (2021).
[6] L. Fiedler, N. Hoffmann, P. Mohammed, G. A. Popoola, T. Yovell, V. Oles, J. A. Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol. 3, 045008 (2022).
[7] L. Fiedler, N. A. Modine, S. Schmerler, D. J. Vogel, G. A. Popoola, A. P. Thompson, S. Rajamanickam, A. Cangi, Npj Comput. Mater., accepted (2023).

This paper defines a 3D full core neutronics benchmark which is based on the NuScale small modular reactor (SMR) concept. The paper provides a detailed description of the NuScale-like core, a list of expected outputs, and a reference solution to the benchmark exercises obtained with the Monte Carlo code Serpent.

The benchmark was developed in the framework of the Euratom McSAFER project and can be used for verification of computational chains dedicated to 3D full-core neutronics simulations of water cooled SMRs.

The paper is supplemented with a digital data set to ease the modeling process.

BaFe2As2 is the parent compound for a family of iron-based high-temperature superconductors as well as a prototypical example of the spin-density wave (SDW) system. In this study, we perform an optical pump-probe study of this compound to systematically investigate the SDW order across the pressure-temperature phase diagram. The suppression of the SDW order by pressure manifests itself by the increase of relaxation time together with the decrease of the pump-probe signal and the pump energy necessary for complete vaporization of the SDW condensate. We have found that the pressure-driven suppression of the SDW order at low temperature occurs gradually in contrast to the thermally-induced SDW transition. Our results suggest that the pressure-driven quantum phase transition in BaFe2As2 (and probably other iron pnictides) is continuous and it is caused by the gradual worsening of the Fermi-surface nesting conditions.

In laser wakefield acceleration, a laser pulse interacts with plasma to accelerate electrons.
These novel small-scale accelerators require an ultra-short, high-intensity laser system. The
intensity and its temporal distribution can be described by the spectrum of the laser. Initially,
this spectrum has the characteristics of a time-varying Gaussian-like shape with several smaller
peaks and fluctuations. Before the laser can be used in experiments, it must be amplified to
the desired intensities. If the initial spectrum is amplified, the uneven intensity distribution of
the Gaussian-like shape can lead to high intensities at the wavelengths at the corresponding
peak positions. These high intensities form a potential threat due to the amount of energy
present over a short period, which could lead to the loss and destruction of laboratory equip-
ment. Consequently, the spectrum must be equalized in gain. To achieve gain equalization,
the shape of the spectrum must be changed accordingly, subject to the time-varying unmodi-
fied initial spectrum.
One option for performing the spectral shaping is the ”Mazzler” device developed and con-
structed by the French companies, Fastlite and Amplitude technologies. This device can modify
an optical input beam in a flexible manner and be adjusted to complex settings. However, this
is currently performed by an proprietary feedback loop shipped with the device. Consequently,
the details and inner workings of this software are inaccessible. The feedback loop has only a
single mode of operation, which is the purposing of a single predefined spectral target. This
target is the equalization of the spectral gain, in which the intensities of the spectrum are
more evenly distributed, thereby allowing for better amplification. While this modification of
the spectrum is achieved by the feedback loop to a reliable and sufficient degree, multiple iter-
ations of the underlying algorithm are needed to reach the desired state. Since the execution
of each of these steps requires manual interaction, the question of a faster solution arises.
Approaching this task in a data-driven manner is a promising direction for achieving this, since
the corresponding methods allow utilization of already existing experience in the form of data,
gained by modifying spectra in the past. Unlike the current feedback loop, this would imply that
prior executions in previous optimization procedures were not forgotten, but used to build a
model capable of reaching the desired goal more quickly. Furthermore, a method capable of
this could potentially also be used to perform other modifications to the spectra, demonstrat-
ing promising features important for specific use cases such as laser wakefield acceleration.
The generation and optimization of settings for the Mazzler device with neural networks is
the major task introduced in this thesis. An actor-critic model with multiple adaptations of the
algorithm and the underlying models is presented and proposed as an novel approach to this
problem. These models are capable of optimizing in a large, continuous domain through the
exploration-based generation of data, enabling to reach states not present in any available
data. This makes them especially suitable for the optimization of Mazzler settings to modify
spectra in an unprecedented manner. Furthermore, extensive data-related processing to re-
strict the state and action-space of the method are investigated to enable stable operation
and improved efficiency of the hardware in the laboratory. Corresponding results gathered
over multiple days in the DRACO laser laboratory of HZDR are presented with the proposed
method controlling the Mazzler device. Additionally, since execution of these experiments re-
quires hardware interaction, an implementation of this functionality is presented.

In the present work, the two-fluid model (TFM) is coupled with the population balance model (PBM) to trace the spatial and temporal change of bubble size and interfacial area concentration (IAC) in flashing flows. The model is first validated for bubble growing in stagnant superheated liquid, and satisfactory predictions of the bubble size under low and moderate superheat are obtained. It is then applied to flashing pipe flows, which are characterized by low superheat and high turbulence intensities. The results show that in these cases, coalescence and breakup are important phenomena changing the bubble size distribution in addition to growth. The neglect of their contribution leads to a significant under-prediction of the bubble size and consequently over-prediction of IAC. In addition, choosing an appropriate closure for interfacial heat transfer coefficient (HTC) is another key point in flashing simulation. In high-Reynolds cases (e.g. Re > 10^6), the enhancement due to turbulence is nonnegligible.

n this paper, we present an experimental investigation that centers on exploring the fluid dynamics within a
precessing cylinder. Our research is part of the DRESDYN project at Helmholtz-Zentrum Dresden-Rossendorf,
specifically focusing on the precession dynamo experiment. The primary objective of our study is to examine how
different rotation configurations influence the dominant flow modes inside the precessing cylinder, specifically
considering the prograde and retrograde rotations. Our main focus lies on two significant flow modes: the directly
forced mode (m1, k1) and the non-geostrophic axisymmetric mode (m0, k2). These modes hold substantial potential
for precession-driven dynamo action. By analyzing the outcomes between the prograde and retrograde
configurations, we gain valuable insights into the prevailing flow patterns within the precessing cylinder.

In the ternary system CsCl – NaCl – H₂O, at a temperature of 298.15 K, a double salt with the stoichiometric formula CsCl∙2NaCl∙2H₂O(cr) is known to be formed. This double salt and the anhydrous CsCl(cr) are the end-members of a solid solution. For the pure double salt, the solubility constant was determined. The obtained value were applied to calculate the solubility diagram also of the quaternary system CsCl – NaCl – KCl – H₂O and the quaternary-reciprocal system Cs⁺, Na⁺ || Cl⁻, SO₄²⁻ – H₂O. The solubility constant together with a solid solution between CsCl∙2NaCl∙2H₂O(cr) and CsCl(cr) were implemented in THEREDA, which extends the applicability of the existing cesium dataset.

This presentation will provide an overview of the coherent THz sources and the user activities at the ELBE Radiation Source. Ideas for new types of measurements and materials to study will be discussed, followed by a look toward DALI, the concept for a new facility at HZDR for advanced accelerator-based THz sources.

Copper is essential for a decarbonised economy. Nevertheless, its primary extraction still relies on fossil fuels, leading to increasing environmental impacts due to declining ore grades. To overcome this paradox, the recovery of copper from electronic waste (WEEE) has been suggested as a solution. Nonetheless, it is essential to ensure that this approach aligns with the principles of circular economy and minimises emissions throughout the entire lifecycle by utilizing renewable resources. The present research applied FactSage and HSC Chemistry softwares for modelling and simulating the pyrometallurgical route of copper recovery from copper scrap and printed circuit boards (PCBs). Furthermore, the recovery of precious metals (Au, Ag and Pd) was examined through a hydrometallurgical route. OpenLCA was used for the life cycle assessment (LCA) of three energy transition scenarios: (1) Conventional Fuels, as case reference; (2) Biochar and Renewable Electricity, and (3) Hydrogen and Renewable Electricity. The results showed a significant reduction in the environmental impact when scenarios 2 & 3 were considered. Remarkably, the carbon footprint was reduced by over 80% in the case of copper scrap (0.3 CO2 eq./kg Cu) and 18% in the case of PCB (2.2 kg CO2 eq./kg Cu). Furthermore, since precious metals are simultaneously produced with copper, the LCA impacts were economically allocated. Despite their significant economic value (up to 70%), the combustion of plastics found in PCBs resulted in higher footprint among all PCB cases.

Lignin hydrogenolysis into monophenols presents a promising route for lignin-based chemical and fuel production but still suffers from harsh reaction conditions (e.g. high temperature and high external H2 pressure). Herein, we report an ultrafine Ni nanocluster anchored on N-doped carbon nanosheets (Ni/LNC) for efficient catalytic transfer hydrogenolysis of poplar organosolv lignin. The catalyst was fabricated through a simple pyrolysis process of lignin‑nickel complex mixed with melamine, in which the lignin coordination greatly improved the Ni dispersion and the strong Nisingle bondN interaction inhibited the Ni nanocluster growth, resulting in the ultrafine particle size (1–2 nm). Under mild conditions (160 °C, 1 h), 22.08% of monophenol yield was obtained over the catalyst, which was significantly higher than those over the two reference catalysts (Ni/AC and Ni/LC) as well as other previously reported Ni-based catalysts. The excellent catalytic activity can be attributed to both the substantial increase in catalytic active sites and the enhancement in H transfer from methanol resulted from the electron-rich N-doped nanosheet support. Finally, magnetically recycled Ni/LNC showed excellent recycling stability. Consequently, this work presents a facile and low-cost approach for the synthesis of N-doped carbon nanosheet supported ultrafine Ni nanocluster and further demonstrates its superior applicability in lignin hydrogenolysis.

In response to China's commitment to meet carbon peaking and carbon neutrality targets, universities are seeking to assess and minimize their greenhouse gas emissions. In this study, a new methodology based on LEAP and LCA was developed to assess the carbon footprint of a medium-sized university campus in eastern China. The emission sources consider six areas: electricity, fuel, transportation, water, waste, and consumption of other materials. The results showed that the campus emitted about 13,877 tonnes of CO2-eq in 2020. In particular, electricity consumption contributed about 77% of the total CO2-eq emissions on campus, while green cover and material recycling resulted in a negative emission of 404.4 tonnes of CO2-eq. In addition, seven common mitigation strategies were proposed to reduce the campus carbon footprint, and budgets would influence the implementation time. It was found that the seven proposed carbon reduction measures could reduce emissions by 97% in 2060, with decarbonisation of electricity being the largest contributor, leading to an emissions reduction of 64.7%. In addition, carbon offsetting is needed to achieve a carbon-neutral campus by 2060.

Air Taylor bubbles in a millichannel filled with water are characterized by an elongated shape, a bullet-shaped nose and a comparatively flat tail. Many experimental and numerical investigations have been performed in the past. Yet, most of them consider Taylor bubbles in a straight channel with constant cross-section. The effect of a local change in the channel geometry on both the bubble shape and the flow fields on each side of the gas-liquid interface is, however, difficult to predict. In this work, we present experimental data obtained in a vertical millichannel, where the flow is moderately obstructed by a constriction, whose ratio ranges from 10 to 36 %. \rhandrey{We find that the Taylor bubble takes an equilibrium position for downward liquid flow with 264.36 < Re < 529.67 and 264.36 < Re < 728.29 for 10.17 % and 18.06 % constriction ratios, respectively}. In this area, an empirical correlation characterizing the bubble head is provided. Other flow regimes, such as bubble breakup, co- and counter-current configurations are identified and shown in the form of a regime map. The results, besides their relevance in process engineering, exhibit high reproducibility and will serve as reference for future interface resolving two-phase flow simulations.

A dataset is considered complete if, in addition to the pure data (e.g. measured values), further information, such as origin and license for use, is also available. This requires not only the complete collection of data and metadata, but also assistance or instructions for collection and use, as well as an infrastructure for storage, publication and unique identification. Such a "value chain" is made up of various processes that should be handled by people in defined roles.

In this context, it is also necessary to provide a technical infrastructure which, on the one hand, generates a precise input mask for the user's specific case, but which, on the other hand, must direct general search queries in a targeted manner to the correct data records. And of course, this entire construct cannot be controlled without rules and documentation, and must be equipped with an adapted training offering and an intuitive user interface. The training offer is also aimed at people with roles or assigned tasks in the data management system to ensure that the roles are performed with the necessary quality by defining the necessary qualifications. A plausibility check, which takes into account the expected flexibility of the system, guarantees the consistency of the data records. In one of the highest levels of sophistication, the plausibility check is followed by a kind of self-healing mechanism that suggests a data set to the user according to the specifications or makes the user's re-intervention obsolete altogether.

In this contribution, the focus will be on the roles and on the interaction with the data management system. All necessary qualifications and tasks are assigned to the roles. The advantage of the subdivision into roles is that it remains open whether the additional tasks are covered by existing or new personnel or whether one person holds several roles. This means that the specific personnel approach can be adapted to the institution's own needs.

Multiple dopant configurations of Te impurities in close vicinity in silicon are investigated using photoelec- tron spectroscopy, photoelectron diffraction, and Bloch wave calculations. The samples are prepared by ion implantation followed by pulsed laser annealing. The dopant concentration is variable and high above the solubility limit of Te in silicon. The configurations in question are distinguished from isolated Te impurities by a strong chemical core level shift. While Te clusters are found to form only in very small concentrations, multi-Te configurations of type dimer or up to four Te ions surrounding a vacancy are clearly identified. For these configurations a substitutional site location of Te is found to match the data best in all cases. For isolated Te ions this matches the expectations. For multi-Te configurations the results contribute to understanding the exceptional activation of free charge carriers in hyperdoping of chalcogens in silicon.

Contactless Inductive Flow Tomography (CIFT) is a flow measurement technique allowing for visualizing the global flow in electrically conducting fluids. The method is based on the precise measurement of very weak induced magnetic fields arising from the fluid motion under the influence of one or several primary excitation magnetic field(s). The simultaneous use of more than one excitation magnetic field is necessary to fully reconstruct three-dimensional liquid metal flows, yet is not trivial as the scalar values of induced magnetic field at the sensors need to be disentangled for each contribution of the excitation fields. Another approach is to multiplex the excitation fields. Here the temporal resolution of the measurement needs to be kept as high as possible. We apply two trapezoidal-shaped excitation magnetic fields with perpendicular direction to each other to a mechanically driven liquid metal flow. The consecutive application by multiplexing enables to determine the flow structure in the liquid with a temporal resolution down to 3 s with the existing equipment.

Alkaline water electrolysis is a mature and cost-effective technology for hydrogen production. By using wind or solar derived energy, the hydrogen produced is a promising approach to replace fossil fuels and establish a net-zero-emission-industry [1]. However, by blocking electrocatalytic sites the generated bubbles cause significant losses in terms of increased overpotential and ohmic resistance losses [2,3]. Therefore, the study of bubble dynamics on porous electrodes commonly used in industrial electrolyzers is essential to improve the overall efficiency of alkaline electrolysis.

In the present study, a novel three electrode cell is introduced to perform parametric studies of H2 evolution on porous electrodes [4]. For this purpose, electrochemical methods are combined with high-speed optical measurements to characterize the electrodes in terms of electrochemical active surface areas (ECSA), bubble size distribution and electrode coverage. The performance of the electrode can then be derived as a function of current density and applied electrolyte flow rate.

References
[1] L. Lüke and A. Zschocke, Alkaline Water Electrolysis: Efficient Bridge to CO2 -Emission-Free Economy, Chem. Ing. Tech., 92 (2020) 70–73.
[2] A. Angulo et al., Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors, Joule 4 (2020) 555-579.
[3] J.R. Lake et al., Impact of Bubbles on Electrochemically Active Surface Area of Microtextured Gas-Evolving Electrodes, Langmuir 38 (2022) 3276-3283.
[4] H. Rox et al., Bubble size distribution and electrode coverage at porous nickel electrodes in a novel 3-electrode flow-through cell, Int. J. Hydrog. Energy 48 (2023) 2892-2905.

Flashing-induced instability (FII) has a significant impact on the safe operation of a natural cir-culation circuit, a phenomenon frequently encountered in the cooling systems of advanced light water reactors. While one-dimensional system codes are commonly used for engineering design and safety analysis of FII, there is a strong academic interest in understanding the underlying physical mechanisms. To address this, high-resolution computational fluid dynamics (CFD) simulations serve as a valuable tool. However, the current state of CFD modeling for phase change two-phase flows, particularly high transient fluctuating flashing flows, is still in its early stages of development. In this study, we establish a CFD model that focuses on interphase heat transfer to analyze FII. By incorporating experimental data from the literature, we investigate the transient flow field and thermodynamic behavior in the riser of the GENEVA test facility. The study provides valuable insights into the non-equilibrium and interfacial transfer phenom-ena during the phase change as well as the effect of high-frequency fluctuation. Additionally, we discuss in detail the challenges associated with FII modeling and the limitations of the current model. We also provide suggestions for potential improvements in future numerical studies.

Characterizing the physicochemistry and microbial diversity of U mine water is a key prerequisite for understanding the biogeochemical processes occurring in these water mass and for the design of an efficient bioremediation strategy. This study has collected and analysed in reference date measurements water samples from two former U-mines (Schlema-Alberoda and Pöhla, Wismut GmbH) in East Germany. The samples from both mines are pH-circumneutral (7.3 and 6.6) and show reducing conditions (E_H: +139 and –91 mV). Interestingly, the U and sulphate concentrations of Schlema-Alberoda mine water (U: 1 mg/L; SO₄ ²⁻: 335 mg/L) are 2 and 3 order of magnitude higher than those of the Pöhla samples (U: 0.01 mg/L; SO₄ ²⁻: 0.5 mg/L), respectively. U, SO₄ ²⁻ and Fe seem to shape the differential microbial diversity of the water from both mines. Microbial diversity analysis revealed the distribution of bacteria with U(VI)-reducing capacity and the ability to maintain the stability of reduced U-species (e.g., Desulfurivibrio, Gallionella and Sulfuricurvum). In addition, water from the mines harbour wood-degrading fungal communities (e.g., composed of Cadophora and Acremonium) providing potential electron donors which promote the growth of U-reducing bacteria. For the design of a bioremediation strategy, we conducted a preliminary U-bioreduction experiment to screen for suitable electron donors (glycerol, vanillic acid and gluconic acid). We also observed that high levels of soluble U (initially present as Ca₂UO₂(CO₃)₃(aq) and UO₂(CO_{3) 3} ⁴⁻), Fe and SO₄ ²⁻ were removed by 98, 95 and 53%, respectively from the mine water by using glycerol as electron donor. The remaining U concentrations after bioreduction meet regulatory standards for beneficial reuse of U mine water. As a whole, the results reveal the chemical factors influencing the microbial community in U mine water and may contribute to the design of bioremediation strategies based on the biostimulation of U-reducing bacteria for low U concentrations in contaminated water.

Electrochemical upgrading of ethanol to acetic acid provides a promising strategy to couple with the current hydrogen production from water electrolysis. This work reports the design of a series of bimetallic Pt-Hg aerogels, where the PtHg aerogel exhibits a 10.5-times higher mass activity than that of commercial Pt/C toward ethanol oxidation. More impressively, the PtHg aerogel demonstrates nearly 100% selectivity toward the production of acetic acid. The operando infrared spectroscopic studies and nuclear magnetic resonance analysis verify the preferable C2 pathway mechanism during the reaction. This work opens an avenue for the electrochemical synthesis of acetic acid via ethanol electrolysis.

Interactions of selenium (Se), a trace element bio-essential at low concentrations but highly toxic at high concentrations, with the most abundant mineral in the Earth's crust, namely pyrite, was investigated over a wide range of time scales. At the nanosecond scale, selenate Se(VI)O42– adsorption onto the net pyrite surface is shown by ab-initio computations to proceed via the formation of a chemical bond between an oxyanion oxygen atom and a surface Fe atom, weakening the other Se-O bonds and reducing Se atom oxidation state. At the hour-to-day scale, adsorption and coprecipitation of selenate and selenite, Se(IV)O32–, were investigated through wet chemical batch experiments at various pH values at different sulfide concentrations. Selenium removal from solution is slower and weaker for selenate than for selenite. After 24h, only 10% of selenate, against 60% for selenite (or even 100% in the presence of sulfide), is removed by the pyrite surface. Independently of its original oxidation state, adsorbed Se is completely reduced to elemental selenium via adsorption or coprecipitation, as shown by XANES spectroscopy. Our EXAFS results, compared to published data on Se-rich pyrite, show a Se to S substitution within the pyrite structure. The reductive coprecipitation mechanism of selenium with pyrite represents valuable new insights for improving our understanding of modern and ancient biogeochemical cycles involving Se. In addition, several industries can benefit from direct applications of our findings, such as water treatment, green technologies and sustainable mining.

The old question of whether the solar dynamo is synchronized by the tidal forces of the orbiting planets has recently received renewed interest, both from the viewpoint of historical data analysis and in terms of theoretical and numerical modeling. We aim to contribute to the solution of this longstanding puzzle by analyzing cosmogenic radionuclide data from the last millennium. We reconsider a recent time-series of ¹⁴C-inferred sunspot data and compare the resulting cycle minima and maxima with the corresponding conventional series down to 1610 A.D., enhanced by Schove's data before that time. We fnd that, despite recent claims to the contrary, the ¹⁴C-inferred sunspot data are well compatible with a synchronized solar dynamo, exhibiting a relatively phase stable period of 11.07 years, which points to a synchronizing role of the spring tides of the Venus-Earth-Jupiter system.

We consider a conventional α–Ω-dynamo model with meridional circulation that exhibits typical features of the solar dynamo, including a Hale-cycle period of around 20 years and a reasonable shape of the butterfly diagram. With regard to recent ideas of a tidal synchronization of the solar cycle, we complement this model by an additional time-periodic α-term that is localized in the tachocline region. It is shown that amplitudes of some decimeters per second are sufficient for this α-term to become capable of entraining the underlying dynamo. We argue that such amplitudes of α may indeed be realistic, since velocities in the range of m/s are reachable, e.g. for tidally excited magneto–Rossby waves.

We introduce machine learning (ML) models that predict the electronic structure of materials across a wide temperature range. Our models employ neural networks and are trained on density functional theory (DFT) data. Unlike other ML models that use DFT data, our models directly predict the local density of states (LDOS) of the electronic structure. This provides several advantages, including access to multiple observables such as the electronic density and electronic total free energy. Moreover, our models account for both the electronic and ionic temperatures independently, making them ideal for applications like laser-heating of matter. We validate the efficacy of our LDOS-based models on a metallic test system. They accurately capture energetic effects induced by variations in ionic and electronic temperatures over a broad temperature range, even when trained on a subset of these temperatures. These findings open up exciting opportunities for investigating the electronic structure of materials under both ambient and extreme conditions.

In this talk, different approaches to keeping the HELIPORT code base maintainable will be presented. The talk will discuss both the tools used to automate various aspects of development and operation of HELIPORT, as well as how certain aspects of development are approached and how the choice of libraries and tooling helps these aspects.

Running a C.W. electron accelerator as a user facility for more than two decades necessitates upgrades or even complete redesign of subsystems at some point. At ELBE, the outdated timing system needed a replacement due to obsolete components and functional limitations. Starting in 2019, with Cosylab as contractor and using hardware by Micro Research Finland, the new timing system has been developed and tested and is about to become operational. Besides the ability to generate a broader variety of beam patterns from single pulse mode to 26 MHz C.W. beams for the two electron sources, one of the benefits of the new system is improved machine safety. The ELBE control systems is mainly based on PLCs and industrial SCADA tools. This contribution depicts how the timing system implementation to the existing machine entailed extensions and modifications of the ELBE machine protection system, i.e. a new core MPS PLC, and how they are being realized.

Für den Betrieb des Elektronen-Linearbeschleunigers am ELBE - Zentrum für Hochleistungsstrahlenquellen arbeiten wir im Bereich SCADA-System seit 2019 mit Kontron AIS GmbH im Rahmen eines Dienstleistungsvertrags zusammen. Wir stellen in der Präsentation den Beschleuniger vor, beschreiben die einzelnen Support- und Projektthemen und die damit verbundenen Vorteile für Betriebssicherheit und Nutzerfreundlichkeit und Wieterentwicklung unseres WinCC Leitsystems.

In recent years, more and more research was conducted to explore smaller and smaller systems that become similar to an
actual micro/nano-robot. The major roadblock regarding their real world implementation is the highly restricted available
volume. In this paper, we introduce folding – hence an origami technology using Al2O3 as building material, which is
compatible with current Si technology. High quality 50 nm thin Al2O3 film is grown by atomic layer desposition, patterned,
thinned and then released from the Si subtrate using SF6 plasma etching. The realized free standing Al2O3 structure would
fold itself at predefined regions due to the stress in the as deposited films. We believe such technology could offer a new
possibility to tackle the problem of efficiently using the volume. Al2O3 could act as both the structural origami material and
the functional gate dielectric material for electronics. This approach enables the feasibility of patterning devices and circuits
on every Al2O3 facet of a 3D object, while the inside volume of this object is still available for 3D bulk device components.
We demonstrate the optimized etching process as well as an emperical improvement of the folding hinges and of the overall
structural stability.

Data processing or analysis workflows are generally understood as processes running without any user intervention where usually only a small set of parameters being provided upon workflow submission, adjustment of which is also limited by low turnaround rates of workflow runs due to scheduling alone. Many types of experimental data analyses require manual experimentation with parameters to succeed, necessitating interactivity and fast iteration. In this talk we present examples of interactive workflow applications at HZDR, from data analysis and simulation; discuss challenges arising from differences to completely automated workflows and lay-out the related data-provenance and project-resource management features we envision for the HELIPORT workflow platform.

Compartmentalisation in a cell occurs by lipid membrane bound organelles or membrane-less organelles (MLOs). MLOs are dynamic liquid-like condensates inside the cell constituted of various biomolecules formed by liquid-liquid phase separation (LLPS). In LLPS, a biomolecule in an aqueous solution de-mixes from a single well-mixed phase to form two phases – a concentrated phase and a dilute phase. It creates a local concentration hotspot for the biomolecule, leading to enhancement of associated biological functions.
Creating two phases from a single well-mixed aqueous phase involves significant restructuring of the hydration water around the biomolecule. These dynamics are expected to play a crucial role in forming two coexisting phases in the same medium. However, the solvent's role in forming biomolecular condensates remains a relatively unexplored territory.
Recent pioneering work from our group has uncovered the critical role of solvent in the phase separation of RNA binding proteins (RBPs) and how differences in local hydration behaviour leads to phase separation. Following up on our previous work, we study how the alteration of hydration dynamics of different RBPs leads to their phase separation and how protein level modifications in the RBP modulate these dynamics.

The operation of nuclear power plants requires a supply of nuclear fuel where uranium plays a substantial role as a primary fissile material. Its extraction from U-bearing minerals and handling may cause a leakage of heavily toxic radioactive pollution, which ends up in water bodies and soil. Therefore, tackling U-contaminated water is crucial to preserve water integrity and quality. Zeolites are known as profound ion exchangers with great affinity towards cationic species present in polluted waters. Various zeolite synthesis routes have made this group of aluminosilicates even more promising to be applied as water purification materials. Here, the synthetic gismondite, faujasite, and Linde type-A zeolites from coal fly-ash were synthesized via tailored, coupled fusion-hydrothermal method and applied to remove aqueous uranium (primarily as 238U) under varying pH, time (sorption kinetics), and initial U concentrations (sorption isotherms). The maximum U uptake was observed for Na–P1 (GIS) zeolite, which equals 48.72 mg U/g, the highest reported value on maximum U adsorption capacity for zeolitic materials. The U adsorption kinetics showed that equilibrium is reached after approximately 3 h of adsorption and that the removal process follows a Freundlich isothermal model for all zeolites, thus preferential adsorption onto heterogeneous surfaces. Advanced spectroscopic studies, including laboratory-scale X-ray Photoelectron Spectroscopy with synchrotron light X-ray Absorption Near Edge Structure in High Energy Resolution Fluorescence Detection mode, revealed that at acidic pH, predominantly an ion exchange between Na+ ions with hexavalent uranyl species takes place. In contrast, in the neutral pH region, the U is immobilized via precipitation in the form of μm-scale mineral aggregates of Na-schoepite: Na(UO2)4O2(OH)55↓. The outcomes of the research study has demonstrated that synthetic zeolites, obtained from industrial by-products such as coal fly-ash, can be successfully valorized to efficient U adsorbents while unveiling the insights to understand the zeolites/U interactions at the nanoscale level.

Electrical impedance spectroscopy (EIS) is a powerful technique to study material properties, e.g., it is highly sensitive to the moisture content of inhomogeneous cementitious materials. This study contributes to the in-situ measurement of the moisture content (MC) in concrete during the decommissioning of nuclear power plants. Thus, a comprehensive investigation of dielectric material properties of concrete has been performed experimentally and over a 10 Hz to 10MHz range of frequencies through alternating current (AC) impedance spectroscopy.

Molybdenum sulfide (MoS₂) has attracted significant attention due to its great potential as a low-cost and efficient catalyst for the hydrogen evolution reaction. Developing a facile, easily upscalable, and inexpensive approach to produce catalytically active nanostructured MoS₂ with a high yield would significantly advance its practical application. Colloidal synthesis offers several advantages over other preparation techniques to overcome the low reaction yield of exfoliation and drawbacks of expensive equipment and processes used in chemical vapor deposition. In this work, we report an efficient synthesis of alloyed Re_xMo_1−xS₂ nanoflakes with an enlarged interlayer distance, among which the composition Re_0.55Mo_0.45S₂ exhibits excellent catalytic performance with overpotentials as low as 79 mV at 10 mA/cm² and a small Tafel slope of 42 mV/dec. Density functional theory calculations prove that enlarging the distance between layers in the Re_xMo_1−xS₂ alloy can greatly improve its catalytic performance due to a significantly reduced free energy of hydrogen adsorption. The developed approach paves the way to design advanced transition metal dichalcogenide-based catalysts for hydrogen evolution and to promote their large-scale practical application.

We report on the development of a pump system for ultrafast optical parametric amplifiers (uOPA) as an upgrade for the existing uOPA at the Petawatt High Energy Laser for heavy Ion eXperiments (PHELIX) and the new Petawatt ENergy-Efficient Laser for Optical Plasma Experiments (PEnELOPE). The system consists of a two-stage chirped pulse amplifier, centered around a high energy Yb:YAG regenerative amplifier that delivers 108 mJ uncompressed output energy, resulting in 92 mJ at 1030 nm after compression, pulse durations of 1.4 ps, a high beam quality of Mx/y2 = 1.02 / 1.16 and a relative energy stability of 0.35 %. A second harmonic generation (SHG) efficiency of up to 70 % is achievable and a maximum pulse energy of 43 mJ at 515 nm has been obtained, which is only limited by the damage threshold of the SHG crystal. A self-phase modulation stage makes this system a widely applicable, self-seedable pump module for uOPA without placing strong requirements on its seed oscillator.

The properties of hydrogen at warm dense matter (WDM) conditions are of high importance for the understanding of astrophysical objects and technological applications such as inertial confinement fusion. In this work, we present extensive new \emph{ab initio} path integral Monte Carlo (PIMC) results for the electronic properties in the Coulomb potential of a fixed ionic configuration. This gives us new insights into the complex interplay between the electronic localization around the protons with their density response to an external harmonic perturbation. We find qualitative agreement between our simulation data and a heuristic model based on the assumption of a local uniform electron gas model, but important trends are not captured by this simplification. In addition to being interesting in their own right, we are convinced that our results will be of high value for future projects, such as the rigorous benchmarking of approximate theories for the simulation of WDM, most notably density functional theory.

Over the last century, antibiotics against bacterial infections have led
to increased life expectancy and quality of people worldwide. Yet the
WHO has brought attention to the increasing resistance development
of bacterial pathogens against antibiotics - many bacteria are already
multi-resistant. In the search for alternatives to classical antibiotics,
nanotechnology and nanoparticles (NP) are moving into the focus of
scientific research. Particular attention is paid to the Nano-silver (Ag-
NP), which has experienced an immense upswing in recent years and is
used in many medical products such as wound dressings or consumer
products. However, are Ag-NPs safe for health and the environment? To
tackle this challenge, conventional methods have been used to explore
nanoparticle resistance. Conversely, these methods have proven to be
limited in terms of labor, cost, and statistical power. In our work,
we intend to overcome these barriers by developing a droplet-based
microfluidic analytical platform as a tool to elucidate the impact and
biological influence of nanoparticles on living microorganisms with high
statistical evaluation and detection efficiency. This method allows the
separation of bacteria into single droplets, the generation of individual
bioreactors, and the screening of bacterial metabolism in the
presence of Ag-NP.

Over the last century, antibiotics against bacterial infections have led
to increased life expectancy and quality of people worldwide. Yet the
WHO has brought attention to the increasing resistance development
of bacterial pathogens against antibiotics - many bacteria are already
multi-resistant. In the search for alternatives to classical antibiotics,
nanotechnology and nanoparticles (NP) are moving into the focus of
scientific research. Particular attention is paid to the Nano-silver (Ag-
NP), which has experienced an immense upswing in recent years and is
used in many medical products such as wound dressings or consumer
products. However, are Ag-NPs safe for health and environment? To
tackle this challenge, conventional methods have been used to explore
nanoparticle resistance. Conversely, these methods have proven to be
limited in terms of labor, cost, and statistical power. In our work,
we intend to overcome these barriers by developing a droplet-based
microfluidic analytical platform as a tool to elucidate the impact and
biological influence of nanoparticles on living microorganisms with high
statistical evaluation and detection efficiency. This method allows the
separation of bacteria into single droplets, the generation of individual
bioreactors, and the screening of bacterial metabolism in the
presence of Ag-NP.

In this presentation we discuss our achievements on the use of fluidic activities for the detection of impact of nanoparticles on microorganisms.

Air pollution and the energy crisis are the two main driving forces behind the development of alternative, environmentally friendly methods of energy production. Photoactive materials can be used both to clean the air and to produce green hydrogen for clean energy. Transition metal oxides are one of the most considered materials for high-performance photocatalysis. In this work, we investigate the effect of millisecond flash lamp annealing (FLA) of TiO2 on the degradation of methyl blue (MB) and methyl orange (MO). To reduce the energy consumption of the TiO2 deposition process, the layers were made using magnetron sputtering at room temperature, followed by millisecond FLA. By controlling the flash energy input, we can tune the phase formation of TiO2 films from pure anatase to mixed anatase/rutile phases. Scanning electron microscopy, positron annihilation spectroscopy, photoluminescence and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Photocatalytic experiments demonstrate that FLA-treated TiO2 films are active in degrading both MB and MO. This makes them attractive not only for the production of green hydrogen, but also for the purification of water from medical contaminants.

We report on the development of an ultrafast optical parametric amplifier (uOPA) front-end for the Petawatt High Energy Laser for heavy Ion eXperiments (PHELIX) and the Petawatt ENergy-Efficient Laser for Optical Plasma Experiments (PE NELOPE). This front-end delivers broadband and stable amplification up to 1 mJ per pulse while maintaining a high beam quality. Its implementation at PHELIX allowed to bypass a front-end amplifier that was known to be a source of pre-pulses. With the bypass, an amplified spontaneous emission (ASE) contrast of 4.9·10−13 and a pre-pulse c ntrast
of 6.2·10−11 could be realized. Due to its high stability, high beam quality and its versatile pump amplifier, the system
offers an alternative for high-gain regenerative amplifiers in the front-end of vario