Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Since 2009, the DREAMS (DREsden Accelerator Mass Spectrometry) facility offers users to do their own sample preparation for AMS-targets. Several projects aimed at analysing ¹⁰Be, ²⁶Al, and ³⁶Cl as BeO, Al₂O₃, and AgCl, respectively. In cooperation with other AMS-facilities, also actinides (in Fe₂O₃) and ⁶⁰Fe from Fe₂O₃ are measured. Thus, one of the essential steps for many projects is a hydroxide or silver chloride precipitation. For the determination of in-situ or atmospheric ²⁶Al in marine and terrestrial sediments, we had sometimes unaccountable low chemical yields, which seemed to be due to redissolving aluminium hydroxide in the last washings. Hence, we investigated these potential losses by inductively coupled plasma mass spectrometry (ICP-MS) as a function of alteration (waiting) times. Indeed, up to 31% of the precipitated Al could be redissolved by immediate triple washings. After 2 h of waiting, this could be reduced to 11%. Further waiting (over-night) resulted in losses of 6% of Al (and equally Be) only. We also tested the behaviour of Fe(III), U(VI) (also as analogue for ~Pu(VI) and Np(VI)), and Er(III) (as analogue for Am(III), Cm(III), Pu(III)) when iron hydroxides are washed. Even including the supernatant, total losses of three times washing of over-night altered hydroxides are as low as 2.6-3.5%. Thus, repeated washing cycles are very advisable to reduce ions such as NH₄ ⁺ and Cl^- before drying and ignition. As we were facing problems with ¹⁰Be contamination in “dirty” ground ice [1], we measured ³⁶Cl and ^natCl by isotope dilution in permafrost ice wedge samples as heavy as 1.6 kg. The chemical yield of AgCl was only 20-35% and is a function of total ^natCl. Thus, we explored preconcentration steps such as ion exchange (DOWEX 1x8, 5 ml), which look promising. Ackn.: Thanks to P. Steier, F. Quinto and S. Weiss. Ref.: [1] Merchel et al., AMS-13.

Microorganisms are ubiquitous and play a pivotal role in the environment. They have significant impact on nutrient cycles (e.g. carbon, nitrogen, sulfur, phosphor, iron) as well as mineral solubilization and precipitation. This talk gives an overview on metal-microbe interactions which are used for industrial applications such as bioleaching, but also highlights detrimental effects such as microbial induced corrosion (MIC), biogenic sulfuric acid corrosion of concrete, acid mine drainage (AMD) and the concomitant release of toxic heavy metals into the environment. Also, some methodology to study such systems, e.g. radiotracers, positron emission tomography (PET), chromatographic methods and mass spectrometry, are presented.

Since 2009, the DREAMS (DREsden Accelerator Mass Spectrometry) facility offers users to do their own sample preparation for AMS targets. Several projects aimed at analysing quartz for in-situ-produced ¹⁰Be and ²⁶Al. The goal is to dissolve quartz only, minimising other troublesome elements such as Al, Be, and Ti from other coexisting mineral phases. Obviously, low stable Al guarantees higher ²⁶Al/²⁷Al, thus, better ²⁶Al-statistics, however, it also helps, with low Ti, to have fewer problems in chemistry, thus, also better ¹⁰Be-statistics. For correct calculation of ages and erosion rates, it is also advisable to have “pure quartz”, i.e. similar target elements as the calibration site used for production rates and no natural ⁹Be. One of the earliest established quartz cleaning methods has been routinely used at DREAMS: H₂SiF₆/HCl on a shaker table at room temperature [1]. In batches of seven samples we find up to 1.8% residue of the original “quartz” mass with a mean maximum value of 0.6% for the latest 17 batches from six different projects. Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDX) identified the most prominent minerals to be zircon Zr[SiO₄], white sillimanite Al₂[O|SiO₄], transparent to blue kyanite Al₂[O|SiO₄], black chromite Fe²⁺Cr₂O₄, and orange rutile TiO₂. For comparison, we have treated 3.5 g of these residues by microwave (MW) digestion resulting in dissolving 31% of the original residue. SEM-EDX analyses of the MW-residue showed mainly pristine kyanite and heavily-attacked sillimanite only. Inductively coupled plasma mass spectrometry of the MW-solution validated the dissolution of Al, Ti, Cr, Fe, and Zr. For a typical 50 g “quartz sample” the microwave method would add more than 3 mg of Ti, over 7 mg of Al and, and worst of all about 25 μg of Be to the sample. Ref.: [1] Brown et al., GCA 55 (1991) 2269.

Aim
Highly tumor-affine compounds with purposeful pharmacological profile are absolutely necessary for early diagnosis of tumor malignancies and their personalized treatment. In this regard, monoclonal antibodies (mAbs) are particularly valuable as these molecules bind to tumor-associated epitopes with high specificity and affinity. The conventional concept of directly radiolabeled tumor-specific mAbs for radioimmunodetection (RID) and -therapy (RIT) has certainly several drawbacks, most prominently the prolonged radiation exposure of healthy tissues and organs. Tumor pretargeting, however, allows the rational use of long-circulating high-affinity mAbs for non-invasive cancer RID and RIT. The work presented here describes successful tumor pretargeting utilizing an EGFR-specific mAb and peptide nucleic acid (PNA) derivatives as the complementary system for specific radionuclide delivery to pretargeted tumor tissues.

Methods
After chemical synthesis, purification and detailed characterization of the individual components including antibody-PNA conjugates and different PNA oligomers, biodistribution studies were carried out using healthy Wistar rats. Finally, the pretargeting approach was evaluated in murine A431 tumor xenografts by single photon emission computed tomography.

Results
After optimizing the pharmacokinetic properties of PNA oligomers and investigating their hybridization properties, a versatile conjugation protocol based on coupling a cysteine-functionalized PNA oligomer to a maleimido-functionalized mAb was elaborated. The in vivo studies demonstrated a rapid and efficient accumulation of activity at the tumor site with a tumor-to-muscle ratio of > 8 and clearly distinguishable tumor visualization.

Conclusion
This successful tumor pretargeting study has demonstrated the high potential of this concept by applying radiolabeled complementary PNA strands as an alternative in vivo recognition and radionuclide delivery system. The next step involves the translation of these results to the application of therapeutic relevant radionuclides.

We have investigated the magnetotransport above the upper critical field (H_c2) in Fe_1.14Te_0.7Se_0.3, Fe_1.02Te_0.61Se_0.39, Fe_1.05Te_0.89Se_0.11, and Fe_1.06Te_0.86S_0.14. The μSR measurements confirm electronic phase separation in Fe_1.06Te_0.86S_0.14, similar to Fe_1+yTe_1−xSe_x. Superconductivity is suppressed in high magnetic fields above 60 T, allowing us to gain insight into the normal-state properties below the zero-field superconducting transition temperature (T_c). We show that the resistivity of Fe_1.14Te_0.7Se_0.3 and Fe_1.02Te_0.61Se_0.39 above H_c2 is metallic as T → 0, just like the normal-state resistivity above T_c. On the other hand, the normal-state resistivity in Fe_1.05Te_0.89Se_0.11 and Fe_1.06Te_0.86S_0.14 is nonmetallic down to lowest temperatures, reflecting the superconductor-insulator transition due to electronic phase separation.

An improved AMS method has been developed at VERA for detecting the long-lived radioisotope ¹⁰Be and for separating it from its isobar ¹⁰B. Recently installed and projected AMS facilities mainly apply a degrader foil followed by an electrostatic or magnetic separator to remove ¹⁰B from the ion beam. This provides the highest suppression of ¹⁰B, but suffers from significant transmission losses of ¹⁰Be ions.
The new method achieves comparable ¹⁰B suppression with a passive absorber, consisting of a stack of Silicon nitride foils. Compared to a gas absorber, the smaller energy straggling in foils allows separation at lower energies. For a tandem accelerator operated at 3 MV, the charge state 2+ instead of 3+ can be used, with a stripping yield as high as 55%. This way, a high overall efficiency is gained. The setup is simple to operate, and provides good precision. We compare this new approach with other methods used at VERA and at other facilities. The foil stack setup was fully characterized with artificial samples from chemically and isotopically well-defined reagents, and is now routinely applied to real samples in various research projects. The new method is straightforward to be implemented, and was already adopted at another facility at higher terminal voltage [1], the use at a tandem with lower terminal voltage is explored in [2].
[1] S. Winkler et al., this conference.
[2] G. Scognamiglio et al., this conference.

Magnetic, transport, and thermal properties of CeCu₂Mg are investigated to elucidate the lack of magnetic order in this heavy-fermion compound with a specific heat value, C_mag/T |_T→0 ≈ 1.2 J/mol K² and robust effective magnetic moments (μ_eff ≈ 2.46μ_B). The lack of magnetic order is attributed to magnetic frustration favored by the hexagonal configuration of the Ce sublattice. In fact, the effect of magnetic field on C_mag/T and residual resistivity ρ₀ does not correspond to that of a Fermi liquid (FL) because a broad anomaly appears at T_max ≈ 1.2 K in C_mag(T )/T , without changing its position up to μ₀H = 7.5 T. However, the flattening of C_mag/T |_T→0 and its magnetic susceptibility χ_T→0, together with the T² dependence of ρ(T ), reveal a FL behavior for T _ 2 K which is also supported by Wilson and Kadowaki-Woods ratios. The unusual coexistence of FL and frustration phenomena can be understood by placing paramagnetic CeCu₂Mg in an intermediate section of a frustration-Kondo model. The entropy, S_mag, reaches 0.87 R ln 6 at T _ 100 K, with a tendency to approach the expected value S_mag = R ln 6 of the J = 5/2 ground state of Ce³⁺.

Worldwide, 5.5 M people die from stroke each year. Currently, stroke is still the third cause of death in industrialized countries and the leading cause of permanent disability in adulthood. About 78% of the incident stroke patients suffer from cerebral ischemia by occlusion of a cerebral vessel, while hemorrhage accounts for ~17% of all strokes [1]. Both conditions are medical emergencies with limited time for treatment. Recanalization by rtPA or thrombectomy are the only available therapeutic options, both being additionally hampered by a number of exclusion criteria. Despite thorough research, mostly in rodent models, no alternative treatment option has so far been successfully translated into clinical routine. Consequently, international academic and industrial expert consortia (STAIR, STEPS, [2]) suggest preclinical research strategies including validation of novel treatment strategies in gyrencephalic animal models. As a result, we subjected adult Merino sheep to (1) stereotaxic application of autologous blood as a model for intracerebral hemorrhage (ICH) [3], or to (2) territorial infarction by surgical occlusion of the middle cerebral artery (MCAO) [4]. We show the characteristics of perilesional deficits after ICH and the evaluation of a novel nicotinic acetylcholine receptor (nAChR) tracer for the identification of inflammation after MCAO by positron-emission-tomography (PET). All experimental procedures were approved by the local authority (animal licenses TVV33/12 and TVV56/15).
The ICH model led to ipsilateral GM and WM ablation and lateralization. The ipsilateral lateral ventricle was compressed and the contralateral ventricle dilated . Voxel-based-morphometry supports the compression of the ipsilateral ventricle, while the ventricle of the olfactory bulb was dilated bilaterally. Diffusion-weighed-imaging (DWI) revealed free diffused water of the hematoma, which was surrounded by reduced diffusion. The diffusion/perfusion mismatch was
calculated with 0.56 (Figure 1). Histological examination of the perilesional zone revealed hypoxic-ischemic neurons and WM vacuolation including axonal degenerations. The plasma protein fibrinogen was detected around small arteries distant from the cavity.
The MCAO model includes the transcranial surgical occlusion of all 3 branches of the MCAO, subsequently was confirmed by MR angiography. Acute ischemic alteration at day 1 were detected by [15O]H2O brain perfusion PET, MR perfusion and DWI, while structural MRI revealed the infarction at d7 and d14.. The infarctions were delineated at day 7 and 14 by FLAIR sequence. However, prominent edema complicated segmentation procedures. PET/MRI showed decreased nAChR tracer signal in the ischemia-related brain regions on day1 and day7, but a significant signal increase in the peri-infarct region on day14. These PET findings were confirmed by ex vivo autoradiography. Preliminary histopathological evaluation attributed the PET signal increase to glial activation and macrophage infiltration.
Peri-hematomal characteristics of the ICH altered brain tissue are comparable to the findings reported in human beings and other animal models. We show preliminary evidence for a protocol to visualize post-stroke neuroinflammation by PET/MRI. These results supports a potential role for our ovine models in translational stroke research.
Fig1: Intracerebral hemorrhage (ICH) in sheep: PWI (perfusion) and DWI (diffusion) were aligned to T2w turbo-spin-echography, resliced and smoothed . Crosshairs located at [-17, 0, 8].
Reference List
(1) Heuschmann, P. U., Busse, O., Wagner, M., Endres, M., Villringer, A., Röther, J., Kolominsky-Rabas, P. L., and Berger, K. Frequency and Care of Stroke in Germany. Akt Neurol. 2010. 37(7), 333-40.
(2) STAIR-group. Recommendations for standards regarding preclinical neuroprotective and restorative drug development. Stroke. 1999. 30(12):2752-58.
(3) Nitzsche, B., Lobsien, D., Geiger, K., Barthel, H., Zeisig, V., Boltze, J., and Dreyer, A. Large Mammals - translational stroke models in sheep. Amos, K. (Ed.). 9th International congress on vascular dementia. Ljubljana. 2015. Medimont. 2016.
(4) Nitzsche, B., Barthel, H., Lobsien, D., Boltze, J., Zeisig, V., and Dreyer, A. Focal cerebral ischemia by permanent middle cerebral artery occlusion in sheep - surgical technique, clinical imaging and histopathological results. In: Janowski, M., (Ed.) Experimental Neurosurgery in Animal Models .1 ed. Humana Press; 2016.

MHD Rayleigh-Bénard convection was studied experimentally using the eutectic metal alloy GaInSn inside a box having a square horizontal cross section and an aspect ratio of length/height = 5/1. Systematic flow measurements were performed by means of ultrasound Doppler velocimetry that can capture time variations of instantaneous velocity profiles. Applying a horizontal magnetic field organizes the convective motion into a flow pattern of quasi-two dimensional rolls arranged parallel to the magnetic field [1], [2]. If the Rayleigh number (Ra) is increased over a certain threshold Ra/Q, whereby Q is the Chandrasekhar number, the convection flow undergoes a transition to turbulence. Besides the primary convection rolls the flow measurements reveal regular flow oscillations arising from 2D and 3D deformations of the rolls, Ekman-pumping induced flow as well as smaller side vortices that develop around the convection rolls. The aim of this paper is to give a detailed description of the flow field, which is often considered as quasi 2D. In this paper we demonstrate the importance to take 3D flow effects into account in order to explain the observed flow features. The experiments are accompanied by direct numerical simulations. The comparison between the DNS and the flow measurements shows a very good agreement.

Dresden has been a center of microelectronics already since the 1960s, and this has continued and even been intensified after the German reunification. Fabs by Siemens, later Infineon and Qimonda, and also by AMD, later Globalfoundries were established. While those were mostly production sites, a concerted effort in fundamental research was started in the framework of the German Excellence Initiative. TU Dresden has established the “Exzellenzcluster” called “Center for Advancing Electronics Dresden (cfaed)”. In the first part of my talk I will introduce the concept of this cluster and give an overview about its activities. In the second part I will present some research going on in my institute at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in particular related to the integration of III-V semiconductor nanostructures into silicon. If time permits, I may also say a few words about our research in terahertz spectroscopy utilizing the unique free-electron laser at HZDR.

Dynamos are very important, thats why we performed measurements that are motivated by a dynamo experiment currently under development at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in which the possibility of generating a magnetohydrodynamic dynamo will be investigated in a precessing cylinder filled with liquid sodium. The fluid dynamics of the precession driven dynamo experiment is investigated in a downscaled water experiment. Here, we focus on the emergence of non-axisymmetric time-dependent flow structures in terms of inertial waves which, in cylindrical geometry, form so-called Kelvin modes. Flow measurements based on Ultrasound Doppler Velocimetry (UDV) were conducted in order to identify the dominant wave modes. The azimuthal wavenumber is analyzed by four UDV transducers mounted at different azimuthal positions near the cylinder sidewall with a distance of 90° between neighbouring transducers. A radial array of six UDV transducers is utilized to resolve the radial flow structure. The aim of the work is to understand the flow structure and wave dynamics dependence on the precession ratio and to investigate their Reynolds number scalings. Besides, the results at moderate Reynolds numbers were compared to Direct Numerical Simulations and were found to be in very good agreement (see contribution from Andre Giesecke).

The classification accuracy of remote sensing data can be increased by integrating ancillary data provided by multisource acquisition of the same scene. We propose to merge the spectral and spatial content of hyperspectral images (HSIs) with elevation information from light detection and ranging (LiDAR) measurements. In this paper, we propose to fuse the data sets using orthogonal total variation component analysis (OTVCA). Extinction profiles are used to automatically extract spatial and elevation information from HSI and rasterized LiDAR features. The extracted spatial and elevation information is then fused with spectral information using the OTVCA-based feature fusion method to produce the final classification map. The extracted features have high dimension, and therefore OTVCA estimates the fused features in a lower dimensional space. OTVCA also promotes piece-wise smoothness while maintaining the spatial structures. Both attributes are important to provide homogeneous regions in the final classification maps. We benchmark the proposed approach (OTVCA-fusion) with an urban data set captured over an urban area in Houston/USA and a rural region acquired in Trento/Italy. In the experiments, OTVCA-fusion is evaluated using random forest and support vector machine classifiers. Our experiments demonstrate the ability of OTVCA-fusion to produce accurate classification maps while using fewer features compared with other approaches investigated in this paper.

Lithological mapping in mountainous regions is often impeded by limited accessibility due to relief. This study aims to evaluate (1) the performance of different supervised classification approaches using remote sensing data and (2) the use of additional information such as geomorphology. We exemplify the methodology in the Bardi-Zard area in NE Iraq, a part of the Zagros Fold – Thrust Belt, known for its chromite deposits. We highlighted the improvement of remote sensing geological classification by integrating geomorphic features and spatial information in the classification scheme. We performed a Maximum Likelihood (ML) classification method besides two Machine Learning Algorithms (MLA): Support Vector Machine (SVM) and Random Forest (RF) to allow the joint use of geomorphic features, Band Ratio (BR), Principal Component Analysis (PCA), spatial information (spatial coordinates) and multispectral data of the Advanced Space-borne Thermal Emission and Reflection radiometer (ASTER) satellite. The RF algorithm showed reliable results and discriminated serpentinite, talus and terrace deposits, red argillites with conglomerates and limestone, limy conglomerates and limestone conglomerates, tuffites interbedded with basic lavas, limestone and Metamorphosed limestone and reddish green shales. The best overall accuracy (∼80%) was achieved by Random Forest (RF) algorithms in the majority of the sixteen tested combination datasets.

Bubble column reactors (BCRs) are multiphase contactors, used throughout the chemical process industry for reactions, such as, hydrogenation, oxidation and Fischer-Tropsch syntheses. The work in this report was done as part of a project at HZDR to investigate and further develop understanding of the impact of vertical tube bundle internals (for heat exchange), on the liquid mixing (LM) and mass transfer (MT) in bubble columns. Focus was placed on experimental and theoretical analysis of the liquid axial dispersion coefficient, Dz, and volumetric gas-liquid mass transfer coefficient, kla. A 10 cm diameter bubble column (DN100) was used with various typical tube bundle configurations (triangular and square pitch) and tube sizes (8 and 13 mm). As it is typical for industrial applications, one configuration was equipped with a U tube end and all internal configurations used constant coverage area of ~25 % (typical for the Fischer-Tropsch synthesis). All results were compared with the empty column to account for the influence of internals. A salt tracer pulse was used to introduce a change in liquid conductivity for LM experiments and a step change of oxygen concentration introduced to determine the MT coefficient. The axial dispersion and volumetric MT coefficient were estimated using the axial dispersion model (ADM) for LM and MT, respectively. Furthermore, radial effects were evaluated using the 2D ADM.
Key liquid mixing findings:

• Internals caused turbulence dampening and decreased dispersion in slug flow
• Mixing times increased with addition of internals
• The U tube end mitigated this in the bubble flow regime
• Radial effects were shown to factor in with internals at gas velocities > 10 cm s-1
• Validated 1D ADM for Dz estimation for the empty column from 2-20 cm s-1
• Strong recirculation was induced by the U tube end in the bubble flow regime

• All internals configurations slightly increased mass transfer time
• kla data estimated using the ADM were consistent with literature
• CSTR model was found not to be applicable for the investigated columns

Bubble column reactors are frequently used apparatures regarding multiphase flows and chemical reactions such as the Fischer-Tropsch synthesis and the Methanol synthesis etc. Since most of these reactions are of exothermic nature, the emerging reaction heat has to be suficiently removed from the reactor. Therefore, longitudinal flow heat exchanger tube bundles are immersed into the column, which have the advantage of immediate heat removal at the source and they offer a large amount of specific surface area for good heat removal properties. On the downside, those internals cover a large portion of the reactor’s cross-sectional area, which leads to a strong influence on the hydrodynamics in bubble columns.
The main aim of this thesis was to develop and validate a hydrodynamic model for bubble column reactors with vertical heat exchanging internals. To fulfill this task, an existing phenomenological cell model by Schilling (2014) has been improved and further developed. The model combines several modeling ideas, such as the vertical compartment approach by Shimizu et al. (2000), the horizontal compartment model to capture up- and downflow regions by Gupta et al. (2001) and a two-bubble class model to account for polydispersity (large and small gas bubbles). Furthermore, sub-models for the prediction of flow Patterns (Vitankar and Joshi, 2002) as well as for breakup and coalescence (Liao, 2013) have been implemented. To incorporate the influence of heat exchanger internals, the developed model is based on the idea of multiple up- and downflow regions, as it has been proven by local radial holdup profiles for bubble columns with internals. These holdup profiles show strong fluctuations and follow a polynomial behavior. Therefore, the reactor is compartmentalized even further in horizontal direction according to the number of gas hold-up peaks detected from previous experimentally obtained results by ultrafast X-ray computer tomography.
The model was evaluated for superficial gas velocities ranging from 2 cm s-1 to 12 cm s-1 to cover homogeneous as well as heterogeneous flow regimes. Five internal configurations, namely, two different tube bundle patterns (triangular and square pitch) and two different tube sizes (8 and 13mm) as well as the empty bubble column reactor as counterpart were examined. Furthermore, the influence of a bended bottom structure (cf. u-tube heat exchanger) has been investigated with the developed model. The obtained parameters have been compared to experimental data provided by Seiler (2016) and empirical correlations from the literature (Shah et al. (1982), Akita and Yoshida (1973)). The results for the overall gas hold-up and the bubble size distribution are generally in good agreement with the experimental data and represent a significant improvement to the original phenomelogical cell model. On the other hand, the model predicts an increasing Sauter mean diameter, which is contrary to experimental findings for empty bubble column reactors. Those results also influence the specific gas-liquid interfacial area and the volumetric mass transfer coefficient significantly. Furthermore, the model is not able to represent the characteristics of the different internal configurations.
Finally, a sensitivity analysis after Plackett and Burman (1946) was carried out to determine the model’s stability and robustness against parameter changes.

Objectives
Integration of multiple imaging modalities onto a single scaffold obviates the need to administer several compounds with different pharmacokinetics, increases the sensitivity of the detection and gives a deeper insight into the pathophysiological processes. This requires a scaffold with multiple attachment sites, a high tumor binding affinity, and a rapid renal elimination profile. In this regard, dendritic polyglycerols (dPGs) are well-defined, globular, highly biocompatible macromolecules with a nano-size (2-20 nm), narrow size distribution (PDI <1.26) and numerous surface functionalities, which make them amenable to a wide range of chemical modifications [1]. Previous studies done on 3H and 64Cu radiolabeled dPGs show their great potential as platforms for diagnostic applications [2]. Here, the development of dPGs as dual-modal agents for epidermal growth factor receptor (EGFR) specific tumor imaging is described.

Methods
A one-pot strategy was employed for simultaneous attachment of fluorescent labels for optical imaging (cy3/cy7) and macrocyclic chelators based on a 1,4,7-triazacyclononane system for 64Cu (PET tracer) to thiol anchoring groups of the dPGs. A small camelid single-domain antibody (sdAb) representing a potential recognition agent for EGFR as targeting vector was attached (1). In parallel, a probe with similar surface characteristics but an EGFR unspecific sdAb (control) was synthesized (2). The conjugates were purified using affinity chromatography, which selectively separates the antibody-conjugated multimodal conjugates. In vitro and in vivo studies were conducted to assess its diagnostic potential.

Results
64Cu labeling was achieved under ambient temperature and physiological pH. Binding studies on A431 and FaDu cells using 64Cu and dye-labeled 1 and 2 showed a high specificity, colocalization and a receptor-mediated cellular uptake of 1. Intravenous injection of the 1 and 2 on mouse xenografted models studies using PET and optical imaging revealed an overwhelming tumor accumulation of the EGFR-specific 1 in comparison to the EGFR-unspecific 2 and a minimum off-target accumulation of both conjugates.

Conclusions
These results show the great potential of dendritic polyglycerols as multimodal platforms for various biomedical applications.

The Tres Marias Zn-Pb-(Ge) deposit in Chihuahua, northern Mexico, is hosted by mid-Cretaceous carbonate rocks. Sulfide ore occurs in a carbonate solution collapse breccia and has been partially altered to zinc silicates and oxides. We have used Rb-Sr sphalerite geochronology and Pb isotope systematics to constrain the age and genesis of the sulfide mineralization. An Rb-Sr sphalerite age of 28.8 ± 1.7 Ma was obtained from a quantitative, two-component paleomixing model. This age coincides with widespread volcanism in the region and is associated with a marked change from a compressional to an extensional tectonic regime. Furthermore, the Pb isotope compositions of galena, sphalerite, and late-stage hydrothermal calcite of the Tres Marias deposit overlap with values for coeval magmatic-hydrothermal, high-temperature Zn-Pb deposits of northern Chihuahua. We conclude that the formation of the Tres Marias deposit is related to magmatism and the onset of Basin and Range extensional tectonics, even though no direct spatial link between magmatic rocks and the mineralization is apparent.

Ge-rich ZrO2 films, fabricated by confocal RF magnetron sputtering of pure Ge and ZrO2 targets in Ar plasma, were studied by multi-angle laser ellipsometry, Raman scattering, Auger electron spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction for varied deposition conditions and annealing treatments. It was found that as-deposited films are homogeneous for all Ge contents, thermal treatment stimulated a phase separation and a formation of crystalline Ge and ZrO2. The “start point” of this process is in the range of 640–700 °C depending on the Ge content. The higher the Ge content, the lower is the temperature necessary for phase separation, nucleation of Ge nanoclusters, and crystallization. Along with this, the crystallization temperature of the tetragonal ZrO2 exceeds that of the Ge phase, which results in the formation of Ge crystallites in an amorphous ZrO2 matrix. The mechanism of phase separation is discussed in detail.

A novel apparatus for the single-shot measurement of the temporal pulse contrast of modern ultra-short pulse lasers is presented, based on a simple yet conceptual refinement of the self-referenced spectral interferometry (SRSI) approach. The introduction of the spatial equivalent of a temporal delay by tilted beams analyzed with a high quality imaging spectrometer, enables unprecedented performance in dynamic, temporal range and resolution simultaneously. Demonstrated consistently in simulation and experiment at the front-end of the PW laser Draco, the full range of the ps temporal contrast defining the quality of relativistic laser-solid interaction could be measured with almost 80 dB dynamic range, 18ps temporal window, and 18fs temporal resolution. Additionally, spatio-temporal coupling as in the case of a pulse front tilt can be quantitatively explored.

Laser proton acceleration history at HZDR in light of medical applications

Progress report on PW commissioning and diagnostics

Earth's magnetic field is generated by convective motions in its liquid metal core. In this fluid, the heat diffuses significantly more than momentum and thus, the ratio of these two diffusivities, the Prandtl number Pr, is well below unity. The thermally-driven convective flow dynamics of liquid metals are very different from Pr ~ 1 fluids, like water and those used in current dynamo simulations. In order to characterize rapidly rotating thermal convection in low Pr number fluids, we have performed laboratory experiments in an aspect ratio H/D = 1.94 cylinder using liquid gallium (Pr ~0.025) as the working fluid. The Ekman number, E, which characterizes the effect of rotation, varies from E = 5x10^-5 to 5x10^-6 and the Rayleigh number, Ra, which characterizes the buoyancy forcing, varies from Ra ~ 2x10^5 to 1.5x10^7. Using measurements of heat transfer effciency, characterized by the Nusselt number Nu, and point-wise temperature measurements within the fluid, we characterize the different styles of low Pr rotating convective flow.
The convection threshold is first overcome in the form of container scale inertial oscillatory modes. At stronger forcing, sidewall-attached modes are identifed for the first time in liquid metal laboratory experiments. These wall modes coexist with the bulk oscillatory modes. At Ra well below the values where steady rotating columnar convection occurs, the bulk flow becomes turbulent. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasi-steady columns, as in Pr ~ 1 fluids, but in the form of oscillatory convective motions. Therefore, the flows that drive thermally-driven dynamo action in low Pr geophysical and astrophysical fluids can differ substantively than those occuring in current-day Pr ~ 1 numerical models. Since oscillatory convection is significantly easier to excite than steady convection, it may be that thermally-driven oscillatory motions will generate dynamo action in planetary settings, well before steady convective flows are even actuated. Furthermore, our experimental results show that relatively low wavenumber, wall-attached modes can be dynamically important in rapidly rotating convection in liquid metals.

We report on first commissioning results of the DRACO Petawatt ultra-short pulse laser system implemented at the ELBE center for high power radiation sources of Helmholtz-Zentrum Dresden-Rossendorf. Key parameters of the laser system essential for efficient and reproducible performance of plasma accelerators are presented and discussed with the demonstration of 40MeV proton acceleration under TNSA conditions as well as peaked electron spectra with unprecedented bunch charge in the 0.5 nC range.

In the framework of the joint research project WASA-BOSS (Weiterentwicklung und Anwendung von Severe Accident Codes – Bewertung und Optimierung von Störfallmaßnahmen) of the Federal Ministry of Education and Research, an ATHLET-CD model for a generic German PWR of type KONVOI was developed. The model is applied to analyze the nuclear power plant response in case of a hypothetical SBLOCA severe accident scenario. The SBLOCA 50 cm² leak is modelled in cold leg No 2 (loop with pressurizer) close to the reactor pressure vessel. The scenario is initiated at nominal power conditions with additional assumptions for multiple systems failures, leading to a core degradation scenario. The model covers the in-vessel phase of the accident including core degradation, cladding oxidation, core quenching, hydrogen production, fission products release, material relocation, and RPV failure. The progress of the accident and timing of the main events is presented. Despite continuous improvement of the severe accidents codes, the model parameters for late accident phenomena are still subject to significant uncertainties. A parameter study investigates the influence of one of those uncertain parameters in ATHLET-CD, the onset of core melt relocation to the RPV lower head, to the late in-vessel phase of accident progression. In the ATHLET-CD model, the relocation to the lower head is initiated by a user defined criterion based on the amount of molten mass. The variation of this parameter within the range of 20 % – 60 % of total core mass leads to a time-shift of the lower head pool-formation of 45 min and a time-shift of all subsequent processes till RPV failure. This analysis contributes to the application and assessment of the ATHLET-CD code for simulation of severe accident scenarios.

Abstract. In the framework of strong field QED, the generation of a residual alternating polarization current is demonstrated, which remains after switching off an external field pulse. This effect is stipulated by inertial properties of the physical vacuum. In the standard vacuum D = 2+1 QED, this current is rapidly damped fast but can be available, apparently, for observation in the graphene, where the Fermi velocity v_F << c plays an analogous role as the light velocity.

Fluid instabilities are characterised by a critical parameter for their onset, an exponential growth phase and a saturated state. The latter may be a steady, periodic or highly fluctuating flow. Investigating a certain instability, large parameter spaces have to be explored by hundreds of simulations, e.g. for finding the mean velocity of the saturated flow. Such parameter studies can crucially be simplified, if the user does not have to specify the simulation time. For this purpose, we present a steady state detection system for OpenFOAM. It terminates simulations automatically if the steady state is reached.

Liquid metal batteries, built as a stable density stratification of two liquid metals separated by a liquid salt , promise to be a cheap means for stationary energy storage. The latter is highly needed for stabilizing highly fluctuating renewable energies in the electric grid. The high resistance of the electrolyte will lead to internal heating and thermal convection in the cell. This flow may be beneficial when enhancing mass transfer, but it must not be strong enough to wipe away the electrolyte layer. We present here a new multiphase solver for thermal convection and some results of such flow in liquid metal batteries.

not yet available

As proton therapy becomes increasingly well established, there is a need for high-quality clinically relevant in vivo data to gain better insight into the radiobiological effects of proton irradiation on both healthy and tumor tissue. This requires the development of easily applicable setups that allow for efficient, fractionated, image-guided proton irradiation of small animals, the most widely used pre-clinical model.
Here, a method is proposed to perform dual-energy proton radiography for inline positioning verification and treatment planning. Dual-energy proton radiography exploits the differential enhancement of object features in two successively measured two-dimensional (2D) dose distributions at two different proton energies. The two raw images show structures that are dominated by energy absorption (absorption mode) or scattering (scattering mode) of protons in the object, respectively. Data post-processing allowed for the separation of both signal contributions in the respective images. The images were evaluated regarding recognizable object details and feasibility of rigid registration to acquired planar X-ray scans.
Robust, automated rigid registration of proton radiography and planar X-ray images in scattering mode could be reliably achieved with the animal’s bedding unit used as registration landmark. Distinguishable external and internal features of the imaged mouse included the outer body contour, the skull with substructures, the lung, abdominal structures, and the hind legs. Image analysis based on the combined information of both imaging modes allowed image enhancement and calculation of 2D water-equivalent path length (WEPL) maps of the object along the beam direction.
Fractionated irradiation of exposed target volumes (e.g. subcutaneous tumor model or brain) can be realized with the suggested method being used for daily positioning and treatment planning. Robust registration of X-ray and proton radiography images allows for the irradiation of tumor entities that require conventional computed tomography (CT)-based planning, such as orthotopic lung or brain tumors, similar to conventional patient treatment.

We present a method for quantitative visualization and parametrization of heterogeneous transport processes at the host-rock – cement interface. As measuring method for spatiotemporal observation of the concentration of a radiotracer (22Na), we apply high-resolution positron emission tomography (PET). For illustration, the study here was conducted on a generic laboratory sample with drill core dimensions of a halite – salt cement contact. By sequential PET-imaging over a period of 70 days, we could delineate the initial patchy tracer distribution and the diffusional propagation of the tracer concentration into the cement. After 10 days, we observed significant propagation of the tracer into the cement. From the propagation pattern, we derived a first approximation of the penetration depth.

In-situ range verification of ion beams during dose delivery is a key for further improving the precision and reducing side effects of radiotherapy with particle beams. The detection and analysis of prompt gamma rays with respect to their emission points, emission time, and emission energy can provide corresponding means. Prompt gamma-ray imaging (PGI) has already been used for range verification in patient treatments with proton beams. The prompt gamma-ray timing (PGT) technique promises range verification at lower hardware expense with simpler detection systems superseding heavy collimators. After proving the principle, this technique is now being translated to the treatment room. The paper presents latest experimental results obtained with clinically applicable PGT hardware in irradiations of plexiglass targets in pencil beam scanning (PBS) mode with proton beams at clinical dose rates. The data were acquired with multiple PGT detection units while the distal layer of an artificial 1 Gy dose cube treatment plan was repeatedly delivered to a solid PMMA target that sometimes comprised a cylindrical air cavity of 5, 10, or 20 mm depth. The corresponding local range shifts were clearly detected and visualized by analyzing position or variance of the prompt gamma-ray timing peaks in PGT spectra assigned to the individual PBS spots. In this context, a major challenge concerning all prompt-gamma based techniques is examined and discussed: collecting the event statistics that is needed for range verification of single pencil beam spots at an accuracy level of a few millimeters.

The Hämmerlein skarn in the Erzgebirge, Germany, is assessed according to its beneficiation potential. A modified approach for automated mineralogy is used to evaluate the economic potential of the compositionally complex Sn ore. The lithological units show significant differences in modal mineralogy and Sn deportment. Petrographic observations and data from automated mineralogy suggest a close spatial relationship between chlorite and cassiterite, possibly pointing towards a cogenetic relationship. The association of these two minerals may be advantageous for beneficiation. Chlorite can easily be detected by a near-infrared detector used in commercially available sorting equipment. Chlorite- and cassiterite-rich rock fragments may thus be identified and separated for further processing by conventional milling, gravity separation and flotation.

A method was developed to determine the modal mineralogy and Sn deportment of a fine-grained skarn ore. Mineral Liberation Analysis and electron probe microanalysis were applied to crushed and uncrushed samples for mineralogical characterization. A comprehensive list of mineral references consisting of energy-dispersive X-ray spectra and information about elemental concentration and density was created. This conventional approach did not achieve reliable results in the characterization of some of the analyzed ore types. Small grain sizes and the variety of Sn-bearing minerals required adding mineral references with manually mixed EDX-spectra, calculated elemental concentrations and densities. Comparison of MLA data using this modified approach with bulk geochemistry and X-ray powder diffraction illustrates very good agreement for all ore-types characterized. The illustrated approach may well be considered for other mineralogically complex ores containing a multitude of ore minerals and complex deportment of metals.

A method was developed to determine the modal mineralogy and Sn deportment of a fine-grained skarn ore. Mineral Liberation Analysis and electron probe microanalysis was applied to crushed and uncrushed samples for mineralogical characterization. A comprehensive list of mineral references consisting of energy dispersive X-ray spectra and information about elemental concentration and density was created. This conventional approach did not achieve reliable results in the characterization of some of the analyzed ore types. Small grain sizes and the variety of Sn-bearing minerals required adding mineral references with manually mixed EDX-spectra, calculated elemental concentrations and densities. The consequences of classifying a data set with a conventional vs a modified mineral reference list are explained in Figure 1. Comparison of MLA data using this modified approach with bulk chemistry and X-ray powder diffraction illustrates very good agreement for all ore-types characterized. The illustrated approach may well be considered for other mineralogically complex ores containing a multitude of ore minerals and complex deportment of rare metals.

A method was developed to determine the modal mineralogy and Sn deportment of a fine-grained skarn ore. Mineral Liberation Analysis and electron probe microanalysis was applied to crushed and uncrushed samples for mineralogical characterization. A comprehensive list of mineral references consisting of energy dispersive X-ray spectra and information about elemental concentration and density was created. This conventional approach did not achieve reliable results in the characterization of some of the analyzed ore types. Small grain sizes and the variety of Sn-bearing minerals required adding mineral references with manually mixed EDX-spectra, calculated elemental concentrations and densities. Comparison of MLA data using this modified approach with bulk chemistry and X-ray powder diffraction illustrates very good agreement for all ore-types characterized. The illustrated approach may well be considered for other mineralogically complex ores containing a multitude of ore minerals and complex deportment of metals.

A method was developed to determine the modal mineralogy and Sn deportment of a fine-grained skarn ore. Mineral Liberation Analysis and electron probe microanalysis was applied to crushed and uncrushed samples for mineralogical characterization. A comprehensive list of mineral references consisting of energy dispersive X-ray spectra and information about elemental concentration and density was created. This conventional approach did not achieve reliable results in the characterization of some of the analyzed ore types. Small grain sizes and the variety of Sn-bearing minerals required adding mineral references with manually mixed EDX-spectra, calculated elemental concentrations and densities. The consequences of classifying a data set with a conventional vs a modified mineral reference list are explained in Figure 1. Comparison of MLA data using this modified approach with bulk chemistry and X-ray powder diffraction illustrates very good agreement for all ore-types characterized. The illustrated approach may well be considered for other mineralogically complex ores containing a multitude of ore minerals and complex deportment of rare metals.

The Hämmerlein orebody is part of the world class Tellerhäuser deposit in the Erzgebirge, Germany, and represents a compositionally complex polymetallic Sn-In-Zn skarn. Current resources amount to 100000t Sn at a cut-off grade of 0.2 wt.%. In addition, 2100 t of In and 270000t of Zn have been estimated. In the late 1970s, 50000t of ore from the Hämmerlein orebody were mined and processed experimentally in a pilot plant, but grade and recovery remained below expectations. Cited reasons for poor recovery include the complex mineralogy and variability in grain sizes of ore minerals [1].
A consortium of German research institutions currently conducts new beneficiation experiments on the Hämmerlein orebody. Determination of the Sn deportment and the characterization of the different lithological (skarn) units are the first steps in this process. For this purpose, three transects in the central part of the Hämmerlein orebody were mapped and a suite of hand specimen collected to represent all relevant lithotypes within the studied part of the orebody. Thin sections were prepared and analyzed using the Mineral Liberation Analyzer (MLA) to obtain quantitative data about mineralogy, mineral grain sizes, intergrowths, and associations. The remaining material of the hand specimen was crushed to 99% <250µm. This granular material was split to produce grain mounts for further mineralogical studies and in order to prepare sample powders for geochemical analysis.
The Hämmerlein skarn orebody can be subdivided into the following three macroscopically distinct lithotypes: 1. magnetite-dominated (40 – 80 wt.% magnetite), 2. sulphide-dominated (> 20 wt.% sphalerite) and 3. silicate-dominated (> 60 wt.% silicates). In the silicate-dominated unit a gradual transition of different silicate minerals enables further discrimination of a chlorite-rich, an amphibole-chlorite-rich, an epidote-pyroxene-rich and a garnet-rich subunit. The hanging and footwall are best described as mica schist and gneiss, respectively.
The primary host mineral for Sn is cassiterite (SnO2) with grain sizes between 1µm and 1mm. Some of the cassiterite has fibrous crystal habit. Significant amounts (ca. 1.4 wt.%) of coarse-grained (50µm to 1mm) cassiterite is present in the chlorite subunit. The amphibole-chlorite subunit contains an average of 0.3 wt.% cassiterite. Samples from other parts of the Hämmerlein orebody indicate significant amounts of cassiterite in the magnetite- and the sulphide-dominated lithotypes as well.
Malayaite (CaSnSiO5) is the second most abundant Sn mineral. It appears in fine-grained aggregates in the amphibole-chlorite subunit and in the magnetite-dominated ore type reaching concentrations of ca. 0.1 wt.%. Notable Sn concentrations were detected by EDX in some examples of titanite, epidote and iron oxides. However, the total amount of Sn in these minerals accounts for less than 10% of the total Sn content of the deposit.
Our preliminary results illustrate that the Sn mineralisation of the Hämmerlein skarn is indeed very complex. Cassiterite dominates, but other minerals (most notably malayaite) do contribute significantly to the deportment. Further studies will aim to quantify the variability of deportment and other resource characteristics, in order to guide mineral processing test work.

Thallium is a trace metal with a toxicity greater than that of Pb, Cd and Hg. This study complements the authors’ previous research, with main focus on contamination by Tl and accompanying metals (Pb, Zn, Cd, and Cu) in sediments from an area historically affected by Pb-Zn smelting in Shaoguan city (northern Guangdong Province, South China). In order to provide complex data on the geochemistry of anthropogenic Tl in sediments, total contents and geochemical fractionation of Tl and the other metals were comparatively studied for two different sediment profiles, core A from the Pb-Zn smelter outlet (a major Tl pollution point-source) and core B from the inlet of the North River (natural water courses near the smelter). Surprisingly high enrichment of Tl was observed across both depth profiles, with varying distribution patterns versus depth. Further comparison of Tl contents and its geochemical fractions in the upper, middle and bottom horizons of core A and core B, in combination with mineralogical phases of the sediments, clearly demonstrated both lateral and vertical mobility of Tl, due to complex processes such as mechanical disturbance/mixing, long-term alteration/dissolution of smelter-derived particles, and vertical migration of Tl through colloidal (or microparticle) transport with alumino-phyllosilicates and Fe/Mn (hydr)oxides. Relatively high abundance of Tl in the labile fractions of all selected sediments from both locations highlights a potentially significant environmental risk to the local ecological system in the near future.

We present an analysis on optimizing performance of a single C++11 source code using the Alpaka hardware abstraction library.
While in previous work Alpaka showed close-to-zero overhead compared to native implementations and similar relative numerical performance on a variety of many-core platforms, in this work we focus on performance optimization of the general matrix multiplication (GEMM) algorithm using a simple tiling strategy by tuning tile size and number of tiles computed in parallel. In addition we analyze the optimization potential available with vendor-specific compilers when confronted with the heavily templated abstractions of Alpaka.
We specifically tested the code for bleeding edge architectures such as Nvidia‘s Tesla P100, Intel‘s Knights Landing (KNL) and Haswell architecture as well as IBM‘s Power8 system. On some of these we have been able to reach almost 50% of the peak floating point operation performance using the aforementioned means. When adding compiler-specific #pragmas we were able to reach 5 TFLOPs/s on a P100 and over 1 TFLOPs/s on a KNL system.

Das Kompetenzzentrum Ost für Kerntechnik ist ein regionaler Zusammenschluss der kerntechnischen Einrichtungen mit dem Ziel, die kerntechnische, strahlentechnische und radiochemische Ausbildung an den sächsischen Ausbildungseinrichtungen wie bspw. der TU Dresden und der Hochschule Zittau/Görlitz zu erhalten und möglichst weiter zu entwickeln. Damit einhergehend werden für Lehre und Forschung Versuchseinrichtungen und andere Forschungsinfrastrukturen der Partner gemeinsam genutzt.
Das Kompetenzzentrum Ost für Kerntechnik hat sich die Sicherung des akademisch gebildeten Fachkräftenachwuchses in Universitäten, Hochschulen, Instituten, bei Kernkraftwerksbetreibern und -herstellern sowie in Behörden und Gutachtern zum obersten Ziel gemacht. Dazu werden die einschlägigen Anstrengungen der Mitgliedsorganisationen durch die Vertreter der einzelnen Unternehmen des Kompetenzzentrums koordiniert, um für effizienten Wissenstransfer und Kompetenzerhalt Sorge zu tragen.
Durch den politischen Beschluss bezüglich des Umbaus des Energieversorgungssystems in Deutschland und den damit verbundenen Entscheidungen zur Beendigung der Stromerzeugung aus Kernenergie bis Ende 2022 hat auch für die Mitglieder des Kompetenzzentrums Ost eine Zäsur im Bereich Lehre und Forschung zur Folge. Neben einer deutlichen Reduzierung der Forschungsförderung seitens der Industrie schlägt sich das auch in sinkenden Studenten- und Doktorandenzahlen nieder.
Im Vortrag werden die aktuellen Lehr- und Forschungsaktivitäten der Mitglieder des Kompetenzzentrums Ost mit besonderem Augenmerk auf die gemeinsam bearbeiteten Projekte vorgestellt und Perspektiven zukünftigen Wirkens aufgezeigt.

Our scanning tunneling microscopy and X-ray photoelectron spectroscopy experiments along with first-principles calculations uncover the rich phenomenology and enable a coherent understanding of carbon vapor interaction with graphene on Ir(111). At high temperatures, carbon vapor not only permeates to the metal surface but also densifies the graphene cover. Thereby, in addition to underlayer graphene growth, upon cool down also severe wrinkling of the densified graphene cover is observed. In contrast, at low temperatures the adsorbed carbon largely remains on top and self-organizes into a regular array of fullerene-like, thermally highly stable clusters that are covalently bonded to the underlying graphene sheet. Thus, a new type of predominantly sp2-hybridized nanostructured and ultrathin carbon material emerges, which may be useful to encage or stably bind metal in finely dispersed form.

For lattice Monte Carlo simulations parallelization is crucial to make studies of large systems and long Simulation time feasible, while sequential simulations remain the gold-standard for correlation-free dynamics. Here, various domain decomposition schemes are compared, concluding with one which delivers virtually correlation-free simulations on GPUs.
Extensive simulations of the octahedron model for 2 + 1 dimensional Kardar–Parisi–Zhang surface growth, which is very sensitive to correlation in the site-selection dynamics, were performed to show self-consistency of the parallel runs and agreement with the sequential algorithm. We present a GPU implementation providing a speedup of about 30× over a parallel CPU implementation on a single socket and at least 180× with respect to the sequential reference.

Überblicksvortrag über DECT

The electronical properties of f-elements, especially of the actinides, are a very puzzling topic to investigate. The frontier orbitals (5f, 6d, 7s) all lying in a similar energy regime along with open shells and relativistic effects contribute to a very complex situation, where single-reference methods like DFT and Hartree-Fock are not suitable any more1. In recent years, the investigation of actinides in combination with organic ligands revealed a very rich chemistry with many forms of coordination and chemical bonding. Besides that, many visually appealing and intuitive tools have been developed, with which the chemical bond can be analysed. These tools for bond analysis include natural-bonding orbitals (NBO) and the methods of real-space bonding analysis, e.g. quantum theory of atoms in molecules (QTAIM), bond path analysis, the electron localisability indicator (ELI-D) and non-covalent interaction plots (NCI). The aim of this study is therefore to apply these bond analysis tools to a range of tetravalent actinide complexes with N-donor ligands, like Schiff bases and amidinates (Figure 1), to elucidate their complicated electronic properties. The influence of spin-orbit coupling on the chemical bonding in terms of ELI-D2 as well as thermodynamic computations on the stability of the complexes will be presented. In addition, various spectra, such as NMR and IR, acquired from the calculations will be compared with the experimental results to understand the chemical properties of the actinides and predict yet unknown complexes.

As the mining industry is facing an increasing number of issues related to its fresh water consumption, the role of water chemistry on the efficiency of froth flotation has recently become a particularly hot topic. In order to tackle the uncertainty of the flotation response when the water quality is changing, flotation tests are generally being carried in different water qualities to determine the shift of the grade – recovery curve.
Despite providing valuable information on the flotation response, the currently used approach does not deliver the required data for the simulation of a flotation circuit. Consequently, a novel approach needs to be implemented and provide a framework for such simulation and predictive modeling.
In this paper, the limitations of the currently used approach to predict the influence of water chemistry on froth flotation are highlighted. A simulation-based approach is presented as an alternative, along with the advantages and potentially considerable outcomes of this methodology for the sustainable use of fresh water in the mineral processing industry.

Detection and quantification of a variety of micro-and nanoscale entities, e.g. molecules, cells, and particles are crucial components of modern biomedical research, in which biosensing platform technologies are playing a vital role. Confronted with the drastic global demographic changes, future biomedical research entails continuous development of new-generation biosensing platforms targeting even lower costs, more compactness, higher throughput, sensitivity and selectivity. Among a wide choice of fundamental biosensing principles, magnetic sensing technologies enabled by magnetic field sensors and magnetic particles offer attractive advantages. The key features of a magnetic sensing format include the use of commercially-available magnetic field sensing elements, e.g. magnetoresistive sensors which bear huge potential for compact integration, a magnetic field sensing mechanism which is free from interference by complex biomedical samples, and an additional degree of freedom for the on-chip handling of biochemical species rendered by magnetic labels. In this review, we highlight the historical basis, routes, recent advances and applications of magnetic biosensing platform technologies based on magnetoresistive sensors.

It was observed, that the RT-PICLS code ran by FWKT on the hypnos cluster was producing an unusual amount of system load, according to Ganglia metrics. Since this may point to an IO-problem in the code, this code was analyzed more closely.

Silicon Photo-Multiplier (SiPM) have attractive features that enable new approaches in detector design. Especially the compact size, the insensitivity to magnetic fields, and the very competitive price, make them a prime candidate for use in detectors for particle therapy. To validate their usability in the secondary radiation field of particle therapy facilities, it is necessary to study their sensitivity to neutron fields of the characteristic spectrum. The talk gives an overview of the plans for such irradiation tests at the OncoRay facility.

A unified set of closures have been applied to simulating different configurations and fluids, i.e. pipe flow and bubble column, air/water and air/metal liquid. The simulated velocity, void fraction and turbulence profiles were compared with the measured ones. Starting from the baseline model for poly-disperse flows the present work is intended to prove the performance of a recently published model for bubble induced turbulence. New knowledge assisting in model assessment and development has been achieved on the basis of experimental and direct numerical simulation investigations. A brief discussion on the further development and future work regarding Eulerian closure models was given.

Die Identifizierung der Hauptaufnahmepfade von technischen Nanopartikeln in Pflanzen ist ein wichtiger Faktor bei der Einschätzung ihres Verbleibs in der Umwelt und der damit verbundenen Risiken. Durch den Einsatz unterschiedlicher Radiomarkierungsmethoden gelang es eine hauptsächlich partikulär stattfindende Aufnahme von CeO2-Nanopartikeln zu zeigen, im Gegensatz zu einer Aufnahme in Form ionischen Cers.

Untersuchungen zum Verbleib von Nanopartikeln (NP) entlang des Wirkungspfades „Klärschlamm – Boden – Pflanze“ sollen die Umweltgefährdung von NP aufzeigen. Dabei steht die Aufnahme von NP durch Pflanzen im Fokus der Untersuchungen.
Durch Versuche mit Hydrokulturen zur Aufnahme von radiomarkierten [48V]TiO2 und [139Ce]CeO2 durch Pflanzen (Sonnenblume, Radieschen, Feldsalat, Weidelgras) sollte das Aufnahmepotential von verschiedenen Pflanzenspezies ermittelt werden. Dazu erfolgte eine Exposition der Versuchspflanzen mit NP im umweltrelvanten Konzentrationsbereich in Leitungswasser (+Fulvinsäure), synthetischem und gereinigtem Abwasser für 96 h. Die Ergebnisse zeigen, dass eine Aufnahme in Pflanzen durchweg erfolgt. Dabei werden nur geringe Mengen im ng-Bereich in die Sprosse der Pflanzen transloziert. Anhand von Messungen mit Energiedispersiver Röntgenspektroskopie (REM-EDX) kann gezeigt werden, dass die NP gößtenteils mit den Zellwänden der Wurzeloberfläche und dem Wurzelapoplasten assoziert sind (Abbildung 1). Durch autoradiographische Aufnahmender radiomarkierten NP konnten außerdem die Verteilungen der NP innerhalb der Pflanze visualisiert werden. Daraus lässt sich ableiten, dass die NP nicht über aktive Transportmechanismen in die Pflanze aufgenommen werden. Maßgeblich für die Verlagerung von NP in die Sprosse ist dabei der transpirationsgetriebene Wasserstrom in die Pflanze. Es kommt zu Ablagerungen der NP entlang der Blattadern und der Blattränder. Weiterhin lässt sich vermuten, dass NP innerhalb der Pflanze Lösungsprozessen unterliegen. Für Sonnenblume konnte beobachtet werde, dass sich CeO2 nach nur einer Woche zum größten Teil aufgelöst hat und das freie ionische 139Ce sich in der kompletten Pflanze verteilt hat.
In Versuchen mit Erdkulturen wurde die Aufnahme von NP in die Pflanze aus mit Erde dotiertem Klärschlamm mit [48V]TiO2 und [139Ce]CeO2 untersucht. Erste Ergebnisse zeigen, dass eine Aufnahme von NP nicht für alle Pflanze nachweisbar ist. Für Weidelgras konnte als einzige der untersuchten Pflanzen, eine Verlagerung von CeO2 aus der Erde in die Pflanze belegt werden. Dabei können nur geringste Konzentrationen von 1 - 4 ng kg-1 nach 14 Tage in der Pflanze nachgewiesen werden. Die Ergebnisse für vergleichbare Untersuchungen mit TiO2 stehen noch aus. Darüber hinaus sind Versuche geplant, die die Bindung der NP an der Bodenpartikeln genauer darstellen sollen.
Abschließend wird eine Risikobewertung erarbeitet, welche regulatorische Maßnahmen erachten soll, um zukünftig die Exposition von NP in die Umwelt zu vermeiden.

In many layered metals, coherent propagation of electronic excitations is often confined to the highly conducting planes. While strong electron correlations and/or proximity to an ordered phase are believed to be the drivers of this electron confinement, it is still not known what triggers the loss of interlayer coherence in a number of layered systems with strong magnetic fluctuations, such as cuprates. Here, we show that a definitive signature of interlayer coherence in the metallic-layered triangular antiferromagnet PdCrO₂ vanishes at the Néel transition temperature. Comparison with the relevant energy scales and with the isostructural non-magnetic PdCoO₂ reveals that the interlayer incoherence is driven by the growth of short-range magnetic fluctuations. This establishes a connection between long-range order and interlayer coherence in PdCrO₂ and suggests that in many other low-dimensional conductors, incoherent interlayer transport also arises from the strong interaction between the (tunnelling) electrons and fluctuations of some underlying order.

We report high field de Haas–van Alphen (dHvA) effect measurements in CeRh₂Si₂ both below and above the first-order 26 T metamagnetic transition from an antiferromagnetic to a polarized paramagnetic state. The dHvA frequencies observed above the transition are much higher than those observed below, implying a drastic change of the Fermi-surface size. The dHvA frequencies above the transition and their angular dependence are in good agreement with band-structure calculations for LaRh₂Si₂, which correspond to CeRh₂Si₂ with localized f electrons. Given that the f electrons are also localized at low fields in CeRh₂Si₂, the Fermi-surface reconstruction is due to the suppression of antiferromagnetism and the restoration of the crystallographic Brillouin zone rather than the delocalization of the f electrons. This example suggests that the intuitive notation of “small” and “large” Fermi surfaces commonly used for localized and itinerant f electrons, respectively, requires careful consideration, taking into account the modification of the Brillouin zone in the antiferromagnetic state, when interpreting experimental results.

We present results of electron paramagnetic resonance (EPR) and neutron diffraction studies of CuCl₂·2NC₅H, which is regarded as one of the best known uniform spin-1/2 Heisenberg antiferro-magnet chain systems. We revealed that at T_N = 1.12 K CuCl₂·2NC₅H₅ undergoes the transition into the magnetically ordered spiral state with Q = (0.5, 0.4, 0.5) r.l.u.. It was shown that the zig-zag interchain interactions result in a noticeable geometrical frustration, also affecting the ordered moment per Cu²⁺ and EPR properties, including the angular dependence of the linewidth. The temperature dependencies of the EPR parameters are discussed.

Heavy mon- and polyatomic ions (Au or Bi) from mass-separated FIB working with LMAIS can cause localized melting at the ion impact point due to the enhanced energy density in the collision cascade [1,2]. The formation of high aspect ratio, hexagonal dot patterns on Ge, Si or GaAs after high fluence, normal incidence irradiation choosing a suited combination of energy density deposition and substrate temperature, which facilitated transient melting of the ion collision cascade volume could be demonstrated [2-5]. In this study the universality of this ion impact-melting-induced, self-organized pattern formation is expanded to the compound semiconductor GaSb under Aunm+ ion irradiation with various conditions in particular, ion species, fluence, energy/atom, temperature and angle of incidence. Calculations of the needed melting energies per atom (Emelt) for different materials show, that GaSb is a preferring candidate for a successful surface patterning by mon- and polyatomic heavy ions whereas i.e. the surface of SiC remains stable under the given conditions. Furthermore the surface modification behavior under Au and Bi heavy ion impact should be compared. HR-SEM, AFM and EDX analysis of irradiated surfaces reveal that for compound semiconductors, additional superstructures are evolving on top of the regular semiconductor dot patterns, indicating superposition of a second dominant driving force for pattern self-organization.

[1] C. Anders, K.-H. Heinig and H. M. Urbassek, Polyatomic bismuth impacts into germanium: Molecular dynamics study, Phys. Rev. B 87 (2013) 245434.
[2] L. Bischoff, K.-H. Heinig, B. Schmidt, S. Facsko, and W. Pilz, Self-organization of Ge nanopattern under erosion with heavy Bi monomer and cluster ions, Nucl. Instr. and Meth. B 272 (2012) 198.
[3] R. Böttger, L. Bischoff, K.-H. Heinig, W. Pilz and B. Schmidt, From sponge to dot arrays on (100)Ge by increasing the energy of ion impacts, Journal of Vacuum Science and Technology B 30 (2012) 06FF12.
[4] R. Böttger, K-.H Heinig, L. Bischoff, B. Liedke, R. Hübner, and W. Pilz,
Silicon nanodot formation and self-ordering under bombardment with heavy Bi3 ions, physica status solidi – Rapid Research Letters 7 (2013) 501.
[5] L. Bischoff, R. Böttger, K.-H. Heinig, S. Facsko, and W. Pilz, Surface patterning of GaAs under irradiation with very heavy polyatomic Au ions, Applied Surface Science 310 (2014) 154.

Surface patterning based on self-organized nano-structures on i.e. semiconductor materials formed by heavy mono - and polyatomic ion irradiation from Liquid Metal (Alloy) Ion Sources (LMAIS) is a very promising technique [1,2]. To overcome the lack of only very small treated areas by applying a Focused Ion Beam (FIB) instrument this technology was transferred into larger single-end ion beam systems like an ion implanter. Main component is an ion beam injector based on high current LMAIS, developed for space propulsion systems [3] combined with suited ion optics allocating ion currents in the µA range in a nearly parallel beam of a few mm in diameter. The mass selection of the needed ion species can be performed either by an introduced ExB mass separator (Wien filter) and/or the existing magnet of the ion implanter itself which also can define the final ion energy up to 200 keV.
Different types of LMAIS [4] (needle, porous emitter, capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a high current ion implanter (Danfysik Series 1090) operating at the HZDR Ion Beam Center (IBC). The obtained results of a large area surface modification (mm²) of Ge at room temperature using Bi2+ polyatomic ions from a GaBi capillary LMAIS is presented and compared with the small area dot structures (µm²) made by mass separated FIB.

[1] L. Bischoff, K.-H. Heinig, B. Schmidt, S. Facsko and W. Pilz, Self-organization of Ge nanopattern under erosion with heavy Bi monomer and cluster ions, Nucl. Instrum. Methods B 272 (2012), 198.
[2] R. Böttger, L. Bischoff, K.-H. Heinig, W. Pilz and B. Schmidt, From sponge to dot arrays on (100)Ge by increasing the energy of ion impacts, J. Vac. Sci. Technol. B 30 (2012), 06FF12.
[3] M. Tajmar and B. Jang, New materials and processes for field emission ion and electron Emitters, CEAS Space J. 4 (2013), 47.
[4] L. Bischoff, P. Mazarov, L. Bruchhaus and J. Gierak, Liquid metal alloy ion sources - An alternative for focused ion beam technology, Appl. Phys. Rev. 3 (2016), 021101.

We report on the continuous-wave and passively Q-switched waveguide laser at the wavelength of ~1024 nm, based on the (Yb0.1Y0.9)3(Sc1.5Ga0.5)Ga3O12 (Yb:YSGG) crystal. The ridged waveguide was fabricated on the surface of 100 at. % Yb:YSGG crystal by the swift ion irradiation and the precise diamond blade dicing. Utilizing this waveguide as the gain medium and resonant cavity, the laser emission at ~1024 nm was realized. Coating the Tungsten Disulfide onto the waveguide surface as the saturable absorber, the Q-switched laser emission was also obtained with the pulse duration of 125 ns.

We report on the fabrication of ridge waveguides and Y-branch beam splitters in KTiOAsO4 nonlinear optical crystal by the combination of 15 MeV oxygen (O5+) ion implantation and femtosecond laser ablation. Guiding properties were investigated at the wavelengths of 633 and 808 nm, respectively, showing high polarization sensitivity of light propagation. Splitting ratios of these beam splitters are dependent on in-coupling alignment. The simulated guiding modal distributions of splitted guided beams, which was based on a reconstructed refractive index profile, shows reasonable consistence with the measured ones. After the stepwise annealing treatment at 473 and 573 K for 1 h each, the propagation losses for these guiding structures have been reduced considerably.

Predefined catalysts have been recently successfully employed for diameter- and chirality-selective CVD growth of single-walled carbon nanotubes (SWCNTs).^[1-3] They simplify the exhausting optimization of parameters for in situ catalyst formation and ensure a very good control of catalyst properties. Using C:Ni nanocomposite templates (NCTs) as catalyst precursors, SWCNTs with a selective, monomodal diameter distribution were obtained. More than the half of the SWCNTs had a diameter of (1.36±0.10) nm.^[3]

While the preparation of NCTs is well defined and controlled, the activation of the NPs for nanotube synthesis by CVD is a critical step that is still not fully understood. Element-resolved scanning and high-resolution transmission electron microscopy and Raman spectroscopy were used to clarify the microstructure of C:Ni NCTs in the different stages of the SWCNT growth. These studies reveal a distinct change of the NCT microstructure by conserving the initial nanocomposite morphology to a very large extend.

[1] F. Yang et al., Nature 510, 522 (2014);
[2] H. An et al., Nanoscale 8, 14523 (2016);
[3] S. Melkhanova et al., Nanoscale 8, 14888 (2016)

Ziel des Vorhabens „NanoSuppe“ ist es den Verbleib von Nanopartikeln (NP) entlang des Wirkpfades „Abwasser-Klärschlamm-Pflanze“, unter Berücksichtung von typischen Prozesssabläufen in kommunalen Kläranlagen, zu untersuchen. Dafür finden Experimente zum Verbleib von NP in Laborkläranlagen statt und der Eintrag von NP in die Umwelt durch Kläranlagen-Effluenten, z. B. Klärschlamm als Dünger, wird erforscht. In Batch und Säulenversuchen werden Erkenntnisse zur Umweltmobilität der NP gewonnen und durch Versuchsreihen in Hydrokultur und Erdkultur die mögliche Aufnahme von NP in Pflanzen untersucht.
Das Projekt zeichnet sich hierbei durch die Verwendung radiomarkierter Nanopartikel aus. Dies ermöglicht eine genaue Quantifizierung und Ermittlung der Verteilung der NP in den untersuchten komplexen Matrizes bei Einsatz umweltrelevanter Konzentrationen. Der Einsatz der Radiotracertechnik erfolgt dabei ausschließlich an Boden-, Pflanzen- und Klärschlammproben im Labor und unter kontrollierten Bedingungen. Es wird ein Prozessmonitoring erzielt und Aussagen zum Verhalten und Verbleib von Nanopartikeln entlang des Wirkungspfades möglich.

The retention of particles in porous media is typically attributed to filtrtation effects such as straning, adsorption, or sedimentation. However, using positron emission tomography (PET) as imaging modality we were able to show the effect of hindrance in concentrated nanofluids due to particle-particle interactions. A flow-through column experiment with a MWCNT nanofluid was devised for optimal particle mobility: strong repulsive interactions between particles and between particles and the matrix (glass beads), inhibiting aggregation and adsorption and a large pore size rendering straining unlikely. Using the PET technique we could observe the transport of the MWCNT nanofluid through the glass bead packing in situ. During pulse injection of the suspension into the porous media the suspension spread out as a horizontal plume at the bottom of the column by “flooding” the respective pore volume. After this pulse injection the subsequently injected water seemed to penetrate the suspension only mobilizing MWCNTs from the top of the suspension plume rather than displacing the bulk of injected nanofluid. This mobilization from the top of the plume is most effective in the central parts of the column where the flow velocity is highest while most of the nanofluid is trapped in more stagnant zones of the pore space at the bottom edges of the column with minimal MWCNT displacement. The mobilized MWCNTs are higly diluted and only visible via the continuous diminishing of the plume from its central top boundry.
These observations can be explained by a pronounced hindrance of the particle transport due to particle-particle interactions in the concentrated suspension (Lamas et al, 2012) which is only overcome at the edges of the nanofluid plume, primarily in the central zones of highest flow velocity. Controlled sedimentation experiments reveal the absence of settling for high MWCNT concentrations due to hindrance. This hindrance which inhibits gravitational settling in turn also inhibits transport, in particular at low flow velocities.
In order to achieve the PET measurements the MWCNTs used in this experiment were oxidzed by oxidative acid treatment and radiolabeled with the positron emitter I-125. In an uncomplicated one-pot synthesis the CNTs were labeled by an electrophilic attack of I+ on the electron-rich CNT side-wall catalyzed by the so-called iodogen 1,3,4,6-Tetrachloro-3α-6α-diphenylglucoluril.

Environmental transformations of nanoparticles (NPs) play a major role in determining their likely fate in the environment and the implications for toxicity, mobility and general risk assessment. A main question in this context is the dissolution of nanoparticles. If a nanoparticle dissolves quickly it may be treated as ionic species in terms of risk assessment, while particulate species can show different tendencies of transport, uptake by organisms and consequently toxicity. Slowly dissolving NPs can exhibit a so-called Trojan-horse effect, transporting and releasing ions at places where said ions would not have been transported – at least not at the same concentrations - without traveling on horseback, i.e. in particulate forms.
Using different radiolabeling techniques we have investigated the dissolution of CeO2 NPs. Through activation by proton bombardment using a cyclotron we have radiolabeled CeO2 NPs with radioactive Ce-139 via a (p,2n) nuclear reaction from Ce-140 to Pr-139 followed by the decay of Pr-139 to Ce-139. Here the radiolabel can be assumed to be uniformly distributed in the resulting [Ce-139]CeO2 NPs. In contrast to this we also have produced [Ce-139]CeO2 NP using an in-diffusion technique where ionic radioactive Ce-139 diffuses into the NPs at elevated temperatures. Here the radiolabel is located close to the surface of the NPs. This results in different leaching kinetics of Ce-139 for the two batches of [Ce-139]CeO2 NPs (Fig. 1). The comparison of the different rates allows us to calculate that about 47 % of the 139Ce introduced by in-diffusion is located in the first atomic layer of the CeO2 NPs. We can show that dissolution plays an insignificant role under environmentally relevant conditions with leaching rates well below 1 % of Ce. However, this still reflects significant changes of the surface of the CeO2, as a dissolution of only 1.5 % corresponds to a complete removal of the first atomic layer.
Furthermore, using the differently labeled [Ce-139]CeO2 NPs we can show that the uptake of Ce into plants when exposed to CeO2 NP is mainly an uptake of particulate CeO2 rather than dissolved ionic Ce.

A set of thin film MnxSi1-x alloy samples with different manganese concentration x≈0.44−0.63 grown by the pulsed laser deposition (PLD) method onto the Al2O3 (0001) substrate was investigated in the temperature range 4–300 K using ferromagnetic resonance (FMR) measurements in the wide range of frequencies (View the MathML source) and magnetic fields (View the MathML source). For samples with x≈0.52−0.55, FMR data show clear evidence of ferromagnetism with high Curie temperatures View the MathML source. These samples demonstrate a complex magnetic anisotropy described phenomenologically as a combination of the essential second order easy plane anisotropy contribution and the additional fourth order uniaxial anisotropy contribution with easy direction normal to the film plane. The observed anisotropy is attributed to a polycrystalline (mosaic) structure of the films caused by the film-substrate lattice mismatch. The existence of extra strains at the crystallite boundaries initiates a random distribution of local in-plane anisotropy axes in the samples. As a result, the symmetry of the net magnetic anisotropy is axial with the symmetry axis normal to the film plane. The principal features of the observed anisotropy are explained qualitatively within the proposed microscopic model.

We report on the enhancement and modulation of nonlinear optical response in an Nd:Y3Al5O12 (Nd:YAG) laser crystal through embedded silver nanoparticles (NPs) fabricated by Ag+ ion implantation. The linear absorption spectrum of the sample clearly reveals a localized surface plasmon resonance (SPR) band from 350 to 700 nm correlated to the Ag NPs. By using the Z-scan technique with femtosecond pulses at a wavelength of 515 nm, which is considered as an optical excitation within the SPR band, the nonlinear refraction index reaches values as high as ∼10–12 cm2/W, enhanced by ∼4 orders of magnitude in comparison to that of unimplanted Nd:YAG (without Ag NPs). In addition, it has been shown that embedded Ag NPs in the Nd:YAG host reveal saturable absorption signifying the nonlinear responses. We have also observed that the nonlinear absorption coefficients depend significantly on the excitation energy and can be modulated by varying the fluence of Ag+ ions.

ODS steels have been known to exhibit anisotropic fracture behaviour and form secondary cracks. In this work, the factors responsible for the anisotropic fracture behaviour have been investigated using scanning electron microscopy and electron backscatter microscopy. Fracture toughness of hot rolled 13Cr ODS steel was determined using unloading compliance method for L-T and T-L orientations at various temperatures. L-T orientation had higher fracture toughness than T-L orientation and also contained more pronounced secondary cracking. Secondary cracks appeared at lower loads than primary cracks in both orientations. Primary crack propagation was found to be preferentially through fine grains in a bimodal microstructure. Grains were aligned and elongated the most towards rolling direction followed by T and S directions resulting in fracture anisotropy. Crystallographic texture and preferential alignment of Ti enriched particles parallel to rolling direction also contributed towards fracture anisotropy.

MHD Rayleigh-Bénard convection was studied experimentally and numerically using a liquid metal inside a box with square horizontal cross section and aspect ratio five. Applying a sufficiently strong horizontal magnetic field converts the convective motion into a flow pattern of quasi-two dimensional rolls arranged parallel to the magnetic field. The aim of this paper is to provide a detailed description of the flow field, which is often considered as quasi 2D. In this paper we focus on the transition from a quasi-two-dimensional state towards a three-dimensional flow occurring with decreasing magnetic field strength. We present systematic flow measurements that were performed by means of ultrasound Doppler velocimetry. The measured data give an insight into the dynamics of the primary convection rolls, the secondary flow induced by Ekman pumping and reveal the existence of small vortices that develop around the convection rolls. The flow measurements are completed by direct numerical simulations. Numerical results and experimental findings show an excellent agreement with respect to the qualitative flow features.

The similar chemical properties of f-block elements are still a challenging task in the separation of nuclear fuel waste material by hydrometallurgical methods. Extractants based on phosphorus (e.g. D2EHPA, PC88A, TBP) are typically used in industrial recovery processes.1, 2 Chelating agents, such as 4-acylpyrazolones received remarkable attention as extractants for rare earth elements.3 Our approach is to achieve suitable reagents for selective separation of lanthanides and actinides by implementing the phosphoryl group in the backbone of pyrazolones. This is the first publication on 4-phosphorylpyrazolones4, 5 with respect to their coordination behaviour towards f-block elements.

This poster presents the main objectives tasks and milestones of a roadmap, which was developed by the COMET/ALLIANCE working group NORM with focus on important priorities within NORM related research.

Conditions for ion track formation in single crystal SrTiO3 and TiO2 (rutile) after irradiations using swift heavy ion beams with specific energies below 1 MeV/amu were investigated in this work. Rutherford backscattering spectroscopy in channeling was used to measure ion tracks in the bulk, while atomic force microscopy was used for observation of ion tracks on the surfaces. Variations in the ion track sizes and respective thresholds were observed after irradiations under random, channeling and near-channeling conditions close to normal incidence. These variations are attributed to the specifics of the electronic stopping power of swift heavy ions under the investigated conditions. In the case of ion channeling, electronic stopping power is reduced and observed ion tracks are smaller. The opposite was found under the near-channeling conditions when lowering of the ion track formation threshold was observed. We attribute this finding to the oscillating electronic stopping power with large peak values. For both materials, thresholds for bulk and surface ion track formation were found to be surprisingly close, around 10 keV nm−1. Obtained results are compared with predictions of the analytical thermal spike model.

The application of multiphase computational fluid dynamics (CFD) simulation for scale-up and intensification of chemical engineering processes bears the potential to identify energy- and resource- efficient solutions. This avoids the need to employ the conventional semi-empirical methods which are expensive and time-consuming.
Such simulations are feasible within the Eulerian two-fluid framework of interpenetrating continua. However, for practical applications, suitable closure relations are needed which describe the physics on the scale of individual bubbles or groups thereof. A suitable closure model for the fluid dynamics of bubbly flows is developed at HZDR. The goal of this development is to establish a predictive model which is validated for a broad range of applications. For this purpose, simulations results are compared with experimental data.
Within the present project, a full Reynolds-stress turbulence model is introduced into the mathematical framework and compared with the two-equation model used so far. In particular, new anisotropic source terms for the bubble-induced turbulence are investigated. Bubbly pipe flows, in which individual components of the Reynolds-stress tensor have been measured, are considered as applications. The simulations are run in OpenFOAM.
Simulation results for the gas fraction, liquid velocity and turbulent kinetic energy are largely found to be in accordance with the experimental measurements. Deviations occur mostly for some cases with larger superficial gas velocity. Reynolds-stress models (RSMs) when extended to include the bubble-induced turbulence demonstrate the potential to predict the Reynolds stresses. The RSMs thereby are able to account for the deficiencies of the two-equation turbulence model.

Dual-energy computed tomography enables the determination of relative electron density and effective atomic number. As this can increase accuracy in radiotherapy treatment planning, a substantial number of algorithms for the determination of the two quantities has been suggested – most of them based on reconstructed CT images. We show that many of these methods share a common theoretical framework. Equations can be transformed from one method to the other by re-definition of the calibration parameters. We suggest that further work should be spent on practical calibration and the reliability of CT numbers rather than on the theoretical framework.

Die Anwendung von Methoden der CFD („Computational fluid dynamics“) für Scale-up und Intensivierung verfahrenstechnischer Prozesse bietet die Möglichkeit, energie- und ressourceneffiziente Lösungen zu identifizieren, deren Untersuchung mit konventionellen halb-empirischen Methoden kostspielig und langwierig wäre.
Eine solche Simulation im großtechnischen Maßstab ist im Rahmen der Euler-Euler Beschreibung möglich, in der Prozesse auf der Skala einzelner Blasen modelliert werden. Ein geeignetes Schließungsmodell für Hydrodynamik und Stofftransport in Blasenströmungen wird am HZDR entwickelt. Ziel dieser Entwicklung ist, ein vorhersagetaugliches Modell zu etablieren, das für einen breiten Bereich von Anwendungsbedingungen validiert ist.
Zu diesem Zweck werden Simulationsrechnungen mit experimentellen Daten verglichen, die zunehmend komplexere Geometrien und Effekte einbeziehen. Auf Basis der jeweils erzielten Übereinstimmung werden Modellerweiterungen und -verbesserungen vorgenommen. Im Rahmen der Diplomarbeit soll die reaktive Absorption von Kohlenstoffdioxid in Natronlauge in Blasensäulen untersucht werden.

Mass transfer from gas bubbles to the surrounding liquid or vice versa is an important consideration in chemical engineering. Frequently such absorption or desorption processes are accompanied by a chemical reaction in the liquid phase. Compared with the fluid dynamics of bubbly flows, modeling and simulation of these processes is much less developed. The present work shows some recent advances made in validating closures for the Eulerian two-fluid framework of interpenetrating continua.

Recently, a new model for the reactive mass transfer during absorption of CO2 in aqueous NaOH was developed, based on using a rather generally applicable expression for the enhancement factor and taking into account the reaction of CO2 with water in addition to that with hydroxide ions [Krauß and Rzehak, Chemical Engineering Science 166 (2017) 193–209]. By substituting the interfacial area concentration estimated from experimental data, good agreement was found for the pointwise measurement of time-dependent pH-value in a bubble column taken from the literature [Darmana et al., Chemical Engineering Science 62 (2007), 2556–2575]. In the present contribution, this mass transfer model is implemented in an Euler-Euler / RANS framework including also the hydrodynamic part of the problem. Hydrodynamic closures were taken the same as applied successfully for a range of different conditions in previous work. However, the accuracy of the coupled model in predicting the measured pH-value is seen to fall behind that of the simple pointwise approximation. This suggests that for the present application, the hydrodynamic part of the model requires further improvement. Possible directions to this end are discussed.

Nuclear weapons tests conducted worldwide have dispersed long-lived and radioactive nuclear debris including plutonium (Pu). A reliable assessment of the environmental impact of these radioactive contaminants and their potential implications for human health requires an understanding of their physical/chemical characteristics at the molecular scale. This lecture focuses particularly on the physical/chemical characterisation of the Pu contaminant, one of the most problematic radioactive contaminants released from nuclear tests, by synchrotron-based X-ray microscopy / spectroscopy. The study reveals direct experimental evidence that the Pu legacy remaining at one of the former testing sites in Australia (Taranaki, Maralinga) exists as particulates of Pu(IV) oxyhydroxide compounds, a very concentrated and low-soluble form of Pu, which will serve as ongoing radioactive sources far into the future. Based on the obtained results, a possible scenario of the physical/chemical transformation of the original Pu materials dispersed in the semi-arid environment at Maralinga can be also deduced. The lecture also highlights the importance of the comprehensive characterization of radioactive contaminants for reliable environmental- and radiotoxicological assessment.

Since fall 2011, the DREsden AMS-facility (DREAMS), has performed routine AMS at the Ion Beam Centre’s (IBC) 6 MV tandem accelerator located at the Helmholtz-Zentrum Dresden-Rossendorf [1, 2]. The accelerator is shared with others for purposes such as ion beam analysis and high-energy ion implantation. Measurements of ¹⁰Be, ²⁶Al, ³⁶Cl, ⁴¹Ca, and ¹²⁹I are routinely performed for a wide range of applications. Samples are prepared in close cooperation with DREAMS’s users, mostly in our two dedicated, high quality laboratories on-site [3]. One particular ion source with a very low long-term memory is used exclusively for measuring the halogens (³⁶Cl and ¹²⁹I) [4]. For measurements of ²⁶Al/²⁷Al ratios we have reduced the background to 6×10^-16. Additionally, we started to investigate the potential for non-routine AMS-nuclide determination (stable and short-lived) for e.g. astrophysical applications.
[1] Akhmadaliev et al., NIMB 294 (2013) 5. [2] Rugel et al. NIMB 370 (2016) 94. [3] Merchel et al. these proceedings [4] S. Pavetich et al., NIMB 329 (2014) 22.

Radiobiology with laser accelerated ion beams

The DREAMS (DREsden AMS) facility [1,2] has been proven to be very suitable for a number of applications. We are broadening our application scope by the implementation of a so-called Super-SIMS (SIMS = Secondary Ion Mass Spectrometry) device [3]. Our system combines the spatial resolution capability of a SIMS (CAMECA IMS 7f-auto) with the pre-existing DREAMS’s capability to remove isobaric molecular signatures in the ion beam. An improvement down to isotopic ratios of ~ 10^-9 -10^-12 is expected, i.e. an order of magnitude better than traditional dynamic SIMS (e.g. [4,5]).
To match the acceptance conditions of our 6 MV Tandetron accelerator, the SIMS device (providing an ion beam with 5 to 10 keV energy) can be raised to a potential of up to -30 kV. The connection between the SIMS device and the accelerator has been realized with a transition lens, which focusses the ion beam to the accelerator entrance. SIMS-extracted ion beams have already been successfully measured on the high-energy accelerator side detector.
First measurements were done with two matrices: a P-doped Si-wafer and a natural galena crystal (PbS). The wafer was analysed for all naturally occurring Si isotopes (²⁸Si, ²⁹Si, ³⁰Si) as well as for ³¹P. Count rates for all of the aforementioned isotopes were measured. Galena was analysed for S isotopes (³²S, ³³S, ³⁴S, ³⁶S). We present ongoing developments, results, as well as plans to extend to other matrices and isotope systems. With more development this ultrasensitive analytical method could be best-suited for analysing geological samples within our resource technology focus.

[1] Akhmadaliev et al., NIMB 294 (2013) 5. [2] Rugel et al. NIMB 370 (2016) 94. [3] J. M. Anthony, D. J. Donahue, A. J. T. Jull, MRS Proceedings 69 (1986) 311-316. [4] Maden, PhD thesis, ETH Zurich 2003. [5] S. Matteson, Mass Spectrom. Rev., 27 (2008) 470.

In this paper we report an approach for the structural analysis of mineral-collector interfaces of (bio)flotation systems by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR FT-IR). The extraction of rare earth metals from electronic waste materials is an important challenge for the recycling industry. In a current project bacteriophage are used as biocollectors to develop a bioflotation model system for the separation of lanthanum phosphate doped with cerium and terbium (LaPO4:Ce3+,Tb3+) from mixed fluorescent phosphors. As an initial analytical concept fluorescence microscopy was successfully applied to investigate particles of spent fluorescent lamp powders and to visualize the bacteriophage on the surface of the waste material. However, due to the restrictions of this technique we are not able to identify the molecular interactions of the bacteriophage with the recycled material. ATR FT-IR was found to be an effective tool to detect the major coat protein of the bacteriophage biocollectors on the surface of the LaPO4:Ce3+,Tb3+ and sense their specific bonding interaction opening the gates for the high level chemical characterization of the interface.

A fundamental question concerning the chemical state of uranium in the binary oxides UO2, U4O9, U3O7, U3O8 and UO3 is addressed. By utilizing high energy resolution fluorescence detection X-ray absorption near edge spectroscopy (HERFD-XANES) at the uranium M4 edge, a novel technique in the tender X-ray region, we obtain the distribution of formal oxidation states in the mixed valence oxides U4O9, U3O7 and U3O8. Moreover, we clearly identify a pivot from U(IV)-U(V) to U(V)-U(VI) charge compensation, corresponding with transition from a fluorite-type structure (U3O7) to a layered structure (U3O8). Such physicochemical properties are of interest to a broad audience of researchers and engineers active in domains ranging from fundamental physics, to nuclear industry and environmental science.

Purpose
To evaluate the dose degradation when treating lung cancer patients with proton pencil beam scanning during free-breathing. We assess if treatments without rescanning are feasible in order to avoid prolonged treatment time, especially for slow scanning facilities.
Material and Methods
For 40 lung cancer patients, 4DCT imaging was used to generate 4D dynamic dose distributions of 3D treatment plans with 3 pencil beam scanning fields optimised with the single field uniform dose technique. Simulations included the use of random breathing states of the patient at start of irradiation resulting in multiple possible 4D dynamic dose distributions per fraction. Complete treatment was assumed to consist of 33 fractions of probabilistically chosen single fractions. Treatments were assumed to be delivered with an IBA universal nozzle without rescanning (1.5ms between spots, 2s between energy layers, spot sigma 4mm at highest energy). Tumour motion amplitude was the maximum displacement in tumour centre-of-mass assessed by the 4DCT. Evaluation was done by looking at under- and overdosage in the target structure. In addition, changes in the dose distribution due to changes in motion and anatomy during treatment were analysed using a repeated 4DCT for 4D dynamic dose calculation in one patient case.
Results
Almost 50% of the patients had tumour motion amplitudes of less than 5mm. For these patients, the simulated dose degradation per fraction was much smaller than for patients with larger motion amplitudes, with 2% versus 12 % average absolute reduction of the V95 (p<0.01), and an average increase in absolute V107 of 2% vs 9% (p<0,01). In no patient case studied was the minimum dose in the target degraded to below 80% of the prescribed dose, and rarely increased above 120%. Simulating a 33-fraction treatment, the mean reduction of the V95 was below 1% for patients with motion amplitudes below 5mm, while for patients with larger motion, V95 was degraded on average by 4% with worst case scenarios of 4% versus 19% (p<0.01), cf. Fig. 1. V107 had an average increase of about 0% and 1% (n.s.), with worst case values of 5% and 15%. The additional analysis of one patient case with a repeated CT revealed a large increase of tumour motion by about 5mm during treatment, resulting in a large dose degradation and partial miss of the target (V95<70%), cf. Fig. 2.
Conclusion
Motion amplitude is an indicator of dose degradation caused by the interplay effect. Fractionation reduces the dose degradation to such an amount that rescanning might be unnecessary for patients with a small tumour motion less than 5mm. Patients with larger tumour motion should not be treated without any kind of motion mitigation technique (e.g. rescanning , gating or breath hold) to prevent tumour underdosage persisting through to the end of fractionated treatment. Furthermore, the tumour motion needs to be assessed during treatment for all patients to quickly react to possible changes in motion which might require a treatment adaptation.

The DREAMS (DREsden Accelerator Mass Spectrometry) facility [1, 2] has been proven to be very suitable for a number of applications. We are broadening our application scope by the implementation of a so-called Super-SIMS (SIMS = Secondary Ion Mass Spectrometry) device [3]. Our system combines the spatial resolution capability of a SIMS (CAMECA IMS 7f-Auto) with the pre-existing DREAMS’s capacity to remove isobaric molecular signatures in the ion beam. An improvement down to ultra-trace element concentrations of 1 µg/g to 100 ng/g is expected, i.e. an order of magnitude better than traditional dynamic SIMS (see e.g. [4, 5]).
To match the acceptance conditions of our 6 MV Tandetron accelerator for all masses from 1 to 300 amu, the SIMS device (providing an ion beam with 5 to 10 keV energy) can be raised to a potential of up to -30 kV. The connection between the SIMS device and the accelerator has been realized with a transition lens, which focusses the ion beam to the accelerator entrance. SIMS-extracted ion beams have already been successfully measured on the high-energy accelerator side detector.
First measurements were done with two matrices: a P-doped Si-wafer and a natural galena crystal (PbS). The wafer was analysed for all naturally occurring Si isotopes (²⁸Si, ²⁹Si, ³⁰Si) as well as ³¹P. Count rates for all of the aforementioned isotopes were measured. Galena was analysed for S isotopes (³²S, ³³S, ³⁴S, ³⁶S). We present ongoing developments, results, as well as plans to extend to other matrices and isotope systems. With more development this ultrasensitive analytical method could be best-suited for analysing geological samples within our resource technology focus.

[1] S. Akhmadaliev, et al., Nucl. Instrum. Meth. B 294, 2013, 5-10.
[2] G. Rugel, et al. Nucl. Instrum. Meth. B 370, 2016, 94-100.
[3] J. M. Anthony, D. J. Donahue, A. J. T. Jull, Mat. Res. Soc. Symp. Proc. 69, 1986, 311-316.
[4] C. Maden, PhD thesis, ETH Zurich, 2003.
[5] S. Matteson, Mass Spectrom. Rev. 27 (5), 2008, 470-484.

Distillation columns are essential to chemical process industries, and most of them are fitted with crossflow trays due to their versatility. Since these columns are expensive in terms of cost and energy consumption, an accurate determination of their separation efficiency is a prerequisite to optimization of their performance by design modification and revamping. This would further reduce the extra trays, added to account for the uncertainties, during the column design. There have been several attempts in the past to understand the nature of liquid mixing and flow patterns on the trays through experiments and CFD simulations, and to relate them with their separation efficiency through CFD, empirical and theoretical models. The present work aims at reviewing the experimental and the simulational studies accomplished to characterize the flow and the mixing patterns on column trays. In particular, a comprehensive review of the existing theoretical efficiency prediction models along with the critical analysis of their strengths and weaknesses is presented. The dependence of the tray efficiency on system and flow properties is also discussed. In addition, a concise strategy on how to process and utilize the experimental data in tandem with mathematical models is proposed. The future of the tray efficiency modeling is anticipated to feature hybrid approaches, i.e. using theoretical models supplemented with fluid dynamics information from experimentally validated CFD models. Thus, knowledge of the existing theoretical approaches is imperative for their improvement and development of the new ones for better tray efficiency predictions.

Cross-flow trays are highly reputed among vapour-liquid contacting devices in distillation columns. Their ability to perform in various operating conditions, low fouling sensitivity, low cost and access for inspections make them potential nominee for column internals. Tray separation efficiency as well as overall performance of the column is strongly dictated by evolving flow patterns on the tray. Liquid plug flow is considered ‘ideal’ at which the maximum tray efficiency can be expected. On the other hand, liquid channelling, bypassing, retrograde flow and stagnant zones are known to be detrimental to tray efficiency. Schubert et. al. (2016) established the wire-mesh sensor as a novel technique to extract liquid flow patterns on trays and presented the effect of variable liquid load and weir design on the flow patterns.
As a follow up, the most common mathematical models, which were recently revisited by Vishwakarma et al. (2016), are applied to associate flow and mixing patterns with tray efficiency. They indicate serious loss in efficiency for the tray with largest stagnant regions. The location of dead zones is also important as most of the mass transfer on large trays happens in their first half. Any stagnant liquid in these areas is highly disadvantageous for the tray to fractionate as per expectations. This contribution will stimulate to develop a new practicable model that can account for the effect of location and type of non-ideality on the tray efficiency.

(1) M. Schubert, M. Piechotta, M. Beyer, E. Schleicher, U. Hampel and J. Paschold, ‘An imaging technique for characterization of fluid flow pattern on industrial-scale column sieve trays’, Chemical Engineering Research and Design, vol. 111, pp.138–146, 2016.
(2) V. Vishwakarma, M. Schubert and U. Hampel, ‘Distillation tray efficiency modelling: a forgotten chapter’, Jahrestreffen der ProcessNet-Fachgruppe Fluidverfahrenstechnik, 16-17 March 2016, Garmisch-Partenkirchen.

The current paper comprises CFD- modelling and simulation of condensation and heat transfer inside horizontal pipes. Designs of future nuclear boiling water reactor concepts are equipped with emergency cooling systems which are passive systems for heat removal. The emergency cooling system consists of slightly inclined horizontal pipes which are immersed in a tank of subcooled water. At normal operation conditions, the pipes are filled with water and no heat transfer to the secondary side of the condenser occurs. In the case of an accident the water level in the core is decreasing, steam comes in the emergency pipes and due to the subcooled water around the pipe, this steam will condense. The emergency condenser acts as a strong heat sink which is responsible for a quick depressurization of the reactor core when any accident happens. The actual project is defined in order to model all these processes which happen in the emergency cooling systems. The most focus of the project is on detection of different morphologies such as annular flow, stratified flow, slug flow and plug flow. The first step is the investigation of condensation inside a horizontal tube by considering the direct contact condensation (DCC). Therefore, at the inlet of the pipe an annular flow is assumed. In this step, the Algebraic Interfacial Area Density (AIAD) model is used in order to simulate the interface. The second step is the extension of the model to consider wall condensation effect as well which is closer to the reality. In this step, the inlet is pure steam and due to the wall condensation, a liquid film occurs near the wall which leads to annular flow. The last step will be modelling of different morphologies which are occurring inside the tube during the condensation via using the Generalized Two-Phase Flow (GENTOP) model extended by heat and mass transfer. By using GENTOP the dispersed phase is able to be considered and simulated. Finally, the results of the simulations will be validated by experimental data which will be available in HZDR. In this paper the results of the first part has been presented.

Blasensäulenreaktoren zählen aufgrund ihrer einfachen Bauweise und ihres ausgezeichneten Wärme-und Stofftransportverhaltens zu einem der häufig genutzten Reaktortypen in der chemischen Industrie. Gegenstand aktueller Forschungsarbeiten innerhalb des DFG Schwerpunktprogramms 1740 „Reaktive Blasenströmungen“ ist die Untersuchung lokaler Transportprozesse, um das Verständnis über die Kopplung von Hydrodynamik und Stofftransport bei reaktiven 2-Phasenströmungen in Blasensäulen zu verbessern. Aufgrund limitierter Messtechnik stellt die Ermittlung von lokalen Konzentrationsfeldern und Stofftransportraten in dichten Blasenströmungen eine besondere Herausforderung dar. In diesem Beitrag werden experimentelle Untersuchungen zum Stofftransport am Beispiel der chemischen Absorption von CO2 vorgestellt, bei der die am HZDR entwickelte Gittersensormesstechnik zur Ermittlung der Konzentration und der Umwandlung ionischer Spezies eingesetzt wird. Für diesen Zweck konnte der Gittersensor anhand eines theoretischen Modells und Validierungsexperimente erfolgreich qualifiziert werden. Die experimentellen Ergebnisse der Stofftransportuntersuchungen in einem Blasensäulenreaktor zeigen die Stofftransportraten für verschiedene Eingangsparameter (z. B. Eingangskonzentration der Natronlauge und Gasdurchsatz des CO2) sowohl in Abhängigkeit des Radius als auch in verschiedenen Höhen des Reaktors.

Solid/liquid equilibria in the system UO2 – ZrO2 are revisited in this work by laser heating coupled with fast optical thermometry. Phase transition points newly measured under inert gas are in fair agreement with the early measurements performed by Wisnyi et al. in 1957, the only study available in the literature on the whole pseudo-binary system. However, a minimum melting point is identified here for compositions near (U0.6Zr0.4)O2, around 2800 K. The solidus line is rather flat on a broad range of compositions around the minimum. It increases for compositions closer to the pure end members, up to the melting point of pure UO2 (3130 K) on one side and pure ZrO2 (2970 K) on the other. Solid state phase transitions (cubic-tetragonal-monoclinic) have also been observed in the ZrO2-rich compositions by Raman spectroscopy and x-ray diffraction. Investigations under compressed air revealed a significant decrease in the melting points down to 2500 K – 2600 K for increasing uranium content (x(UO2)> 0.2). This was found to be related to further oxidation of uranium dioxide, confirmed by x-ray absorption spectroscopy. For example, a typical oxidised corium composition U0.6Zr0.4O2.13 was observed to solidify at a temperature as low as 2523 K.
The current results are important for assessing the thermal stability of the system fuel – cladding in an oxide based nuclear reactor, and for simulating the system behaviour during a hypothetical severe accident.

In glioma patients, linac-based photon beam irradiation is a widely applied therapy, which achieves highly conformal target volume coverage, but is also known to cause side-effects to adjacent areas of healthy tissue. Apart from subjective measures, such as quality of life assessment and neurocognitive function tests, objective methods to quantify tissue damage are needed to assess this impact. Magnetic resonance imaging (MRI) is a well-established method for brain tumor diagnoses as well as assessing treatment response. In this study, we retrospectively assessed volumetric changes of gray matter (GM) and white matter (WM) in glioma patients following photon irradiation using a heterogeneous MRI-dataset obtained in routine clinical practice at different sites with imaging parameters and magnetic field strengths. We found a significant reduction in WM volume at one year (p = 0.01) and two years (p = 0.008) post radio(chemo)therapy whereas corresponding GM volumes did not change significantly (p = 0.05 and p = 0.11, respectively). More importantly, we also found large variations in the segmented tissue volumes caused by the heterogeneous MR data, thus potentially masking more subtle tissue changes over time. On the basis of these observations, we present suggestions regarding data acquisitions in future prospective MR studies to assess such volumetric changes.

We propose an extended smooth profile method which can deal with particle-dynamics dispersed in a binary fluid. The smooth profile method, originally developed for the simulation of particle transport in a homogeneous fluid, has been successfully combined with a binary fluid model based on Ginzburg-Landau free energy functional. In this approach, the three types of interfaces among particles and two fluids are treated as diffuse interfaces. By using the method, we simulated the attachment and detachment dynamics of a colloidal particle to the surface of a position fixed bubble in a Newtonian fluid under various capillary numbers. It is found that the method can reproduce the three micro-processes associated with the particle attachment ((i) particle approach, (ii) collision, (iii) sliding down on the bubble surface) (Gregory et al, 2016). The present method will make it possible to simulate a froth flotation process, where the capture of hydrophobic particles by rising bubbles is of primary importance.

The effective liquid-solid mass transfer (LSMT) has been investigated in solid foam packed reactor under cocurrent gas-liquid downflow. Based on a comprehensive literature analysis, the limiting current technique was adapted successfully to solid foam packings enabling measurements of dynamic mass transfer coefficients at different axial packing positions. The flexible reactor setup was used to analyze the appropriateness of various setup configurations. The LSMT coefficients are presented for two different solid foam pore densities for a wide range of gas and liquid velocities covering trickling and pulsing flow regime. To illustrate the difference in the LSMT dynamic in terms of electric current compared to the liquid holdup at pulse flow, a compartment model is developed. Excellent agreement is achieved between simulations and measurement data. Eventually, the effective mass transfer data are compared with conventional random and structured packings.

Nanostructured materials are gaining increasing importance due to their unique properties resulting from the high surface to volume ratio and the altered characteristics of the nanoscaled building blocks. The properties of these materials depend strongly on their microstructure and thus can be controlled by inducing transformation on the nanoscale. In this work, a simple low energy ion beam irradiation technique is presented that can be used to effectively weld the hydrogen titanate nanotubes into a large-scale network of nanowires. By varying the ion fluence, we are able to fragment the entire nanowire network into uniformly distributed nanocrystalline particles with an average size of 5 ± 2 nm. Three-dimensional computer simulations of the ion irradiation effects on the nanotubes reproduce most of the experimental findings and thus confirm that the early development of the system is governed by atomic collision processes. Our study demonstrates that the selective use of ion irradiation can transform metal-oxide nanotubes into large-scale welded networks of nanowires and further into nanocrystalline particles through nucleation and growth.

Glasses containing copper are promising photonic materials for lasing devices and all-optical components. It has already been shown that the oxidation state of the implants depends on many factors. This paper is going to report on one of them, i.e. the influence of the composition of a silicate glass matrix on the behaviour of the implanted Cu ions before and after a subsequent implantation of oxygen ions.
Three types of silicate glasses having a different extent of cross-linking were implanted with copper ions with an energy of 330 keV and a fluence 1 × 1016 ions cm−2. Then the glasses were implanted with oxygen ions with an energy of 110 keV into the same depth as the already implanted Cu ions. The concentration depth profiles of Cu in the glasses were studied by Rutherford Backscattering Spectrometry. After the implantation, the samples were characterised by optical absorption and photoluminescence spectroscopy. The samples were annealed in ambient atmosphere for 1 h at 600 °C, which is near the transformation temperature of those glasses. The effect of annealing on the distribution of the implants and on the absorption and emission spectra of the as-implanted glasses will be discussed as well

The UV light-induced CO release characteristics of a series of ruthenium(II) carbonyl complexes of the form trans-(Cl) [RuLCl2(CO)2] (L = 4,4’-dimethyl-2,2’-bipyridine, 4’-methyl-2,2’-bipyridine-4-carboxylic acid or 4,4’-dicarboxylic acid-2,2’-bipyridine) have been elucidated using a combination of UV-Vis absorbance and Fourier transform infrared (FTIR) spectroscopies, multivariate curve resolution-alternating least squares (MCR-ALS) analysis, and density functional theory calculations. In acetonitrile, photolysis appears to proceed via a serial three-step mechanism involving sequential formation of [RuL(CO)(CH3CN)Cl2], [RuL(CH3CN)2Cl2], and [RuL(CH3CN)3Cl]+. Release of the first CO molecule occurs quickly (k1 >> 3 min-1), while release of the second CO proceeds at a much more modest rate (k2 = 0.099–0.17 min-1) and is slowed by the presence of electron-withdrawing carboxyl substituents on the bipyridine ligand. In aqueous media (1% DMSO in H2O), the two photo-decarbonylation steps proceed much more slowly (k1 = 0.46–1.3 min-1 and k2 = 0.026–0.035 min-1, respectively) and the influence of the carboxyl groups is less pronounced. These results have implications for the design of new light-responsive CO-releasing molecules (“photoCORMs”) intended for future medical use.

Since several years, the phage surface display technique has been successfully applied for the development of new receptor-ligand pairs for medical purposes, new pharmaceuticals or the elucidation of protein-protein interactions. A comparatively new methodological approach is the use of this technique for bioremediation. In the BMBF-funded German-French project "EcoMetals" we focused on novel innovative biological methods for the extraction of copper and accompanying elements from complex copper-containing ores or tailings. The selective separation of individual industrially relevant chemical elements from complex copper-containing leaching solutions represents a particular challenge. Where established chemical methods do not work due to low concentrations or complex composition of these solutions, selectively binding biological structures could become attractive. Up to now, metal-binding peptides are regarded as particularly promising candidates. We used for the isolation and characterization of nickel- and cobalt-specific peptides a bacteriophage library (Ph.D.C7C Phage Display Peptide Library Kit, New England Biolabs, Inc.) for targeted removal and enrichment of these elements from a complex leaching solution. In this library the minor coat protein pIII is genetically modified leading to the expression of 5 copies phage tail protein containing a foreign heptapeptide loop flanked by a disulfide bridge. From a pool of 109 different peptide motifs, 24 peptides for nickel and 19 peptides for cobalt were isolated in an iterative process, the so-called bio-panning. The binding strength of these phages was compared with the wildtype. Cross binding tests revealed for most of the nickel binding phages also binding capacities for cobalt and vice versa.

Biosorption describes the capability of biomass or biomolecules to bind and concentrate metals via several functional groups. Different organisms and many biopolymers are already known for their potential to capture valuable or toxic metal ions from water streams. The directed engineering of microorganisms or biomolecules in order to modify their specificity and affinity provides a smart tool towards the development of new technologies for metal recovery in an energy and chemical-saving while environmentally friendly way. Biosorptive materials are not only attractive for bioremediation purposes, but also for the concentration and recovery of elements from recycling processes or mining waters. Currently, we are focusing on the development of new bio-sorbents based on self-assembling surface proteins (S-layers), siderophores or short peptides for the selective recovery of accompanying elements in complex copper leaching solutions, industry relevant or toxic metal ions from process water streams such as Ga or As and microparticles containing rare earth elements from compact fluorescent lamp powder. Thereby, specifically and selectively metal binding peptides for particulate materials as well as for ionic species could be identified from commercially available phage libraries using the phage surface display technique. Dependent on the length of the metal binding peptides these libraries contain a pool of phage with nearly 10^7 to 10^9 different genetically engineered peptide motifs presented at their surface. Within the French-German bilateral project “EcoMetals” with the aim of the development of innovative eco-efficient biohydrometallurgy processes for the recovery of strategic and rare metals from primary and secondary resources a phage library containing engineered heptamer peptides was used for screening of specific cobalt and nickel binding peptide motifs. In an iterative biopanning process 22 cobalt and 29 nickel binding peptide motifs could be identified. Comparative single clone binding tests were conducted to identify the strongest binding peptides. These peptides will be used as biological compounds in biosorptive composites for the specific recovery of metal ions from complex aqueous solutions. Cross binding tests revealed for most of the nickel binding phages also binding capacities for cobalt and vice versa. One which has been identified originally as the best cobalt binding phage clone showed a six times enhanced nickel binding capacity in comparison to the wild type phage, whereas the best nickel binding phage clone was able to bind eleven times more cobalt than the wild type.This contribution will give an insight into current research activities in our group focusing on the recently established phage surface display technique and discuss strategies for application directed upscaling.

S-layer proteins appear to be suitable for wide variety of different technical applications due to their distinctive physico-chemical properties and their multifunctional importance.
Since several years the focus has been placed especially on their potential use for biosensor applications. There are many approaches under investigation to develop sensors that are highly specific and sensitive as well as robust, reliable and not expensive. Optical methods currently appear an attractive solution. Colloidal gold nanoparticle suspensions as sensory active systems, for instance, have been the subject of intensive investigations for many years. For the development of potential metal-selective biosensors two different approaches of gold nanoparticles based systems in combination with S-layer proteins are presented. Chemically pre-fabricated gold nanoparticles can be stabilized by various simple or more complex organic molecules such as S-layer proteins. Additionally to the stabilization, the S-layer can serve as capture structure for respective ionic analytes. The interaction of the analyte with the S-layer results in the agglomeration of the gold nanoparticles. Due to the plasmonic activities of the metal nanoparticles this can cause a color change of the solution, which can be detected colorimetrically. This sensor principle has been applied successfully for the detection of arsenic (V). Another promising approach is the use of S-layers as template structures for the production of highly fluorescent, size-controlled gold nanoclusters. These gold nanoclusters can be synthesized directly at the protein by a simple chemical reaction. In combination with the known S-layer-mediated selective and specific binding of ionic analytes, e.g. rare earth elements as surrogates/analogues for intrinsic protein bound Ca2+, a subsequent analyte-induced change in the fluorescence intensity of the gold nanoclusters might be used as sensory system for the detection of such strategic relevant elements.

The Mineral Liberation Analyzer combines an Scanning Electron Microscope (SEM) and multiple Energy Dispersive X-ray detectors with automated quantitative mineralogy software. SEM-based automated mineralogy tools are essential in measuring parameters, such as modal mineralogy, mineral locking, mineral association, theoretical grade - recovery and mineral liberation. Such quantitative information are fundamental to investigate the mineralogical characteristics of an ore and evaluate its mineral processing.
A carbonaceous apatite ore sample from Lao Cai deposit, Vietnam was used in this study. The petrographic, mineralogical and mineral liberation observations showed that the ore sample is quite complex, containing carbonate impurities (dolomite and calcite) and having very fine intergrowth texture. The fine intergrowth in complex apatite ores requires very fine grinding for liberation in flotation.

Any safety assessment of waste disposal concepts requires comprehensive and consistent thermodynamic data for the respective reactive transport modelling. This includes sorption, ion exchange or surface precipitation as major retardation processes. The current lack of respective quality-assured databases for these interface phenomena (invalid reaction formulation, missing consistency, restricted application ranges, and contradictory data) severely hampers a reliable modelling.
This work aims on a re-evaluation of already published sorption raw data based on spectroscopically verified surface complexes and their formation reactions. This shall help to transform the free-for-use digitized sorption data collection RES³T (http://www.hzdr.de/res3t) into a true thermodynamic reference database be used for complex real systems such as rocks or soils following the “Component Additivity” approach. Coupled to this is an extension of RES³T allowing also for the storage of sorption raw data sets. Eventually, a full integration with the thermodynamic reference database THEREDA (http://www.thereda.de) is envisaged to provide a comprehensive database for a holistic geochemical modeling.
Sorption speciation calculations of radionuclides on various mineral surfaces will be presented, showing the actual consequences of inconsistent sorption data that can be found in literature, as well as the possibilities using a validated surface speciation. The latter is mainly based on a combination of ATR FT-IR, TRLFS, and EXAFS which allows to create chemically realistic surface complexing models. In combination with the site-density data (including ones from crystallographic measurements), surface complexation models are deduced that describe the sorption of radionuclides accurately and with less surface species then assumed in a vast number of literature references published in the past. Due to the correct description of the realistic surface chemistry and the internal consistency, these models are more robust to other chemical and environmental conditions (pH, pe, composition of the aqueous phase).
As examples, the sorption of uranium(VI) onto various mineral phases (Al-, Fe- and Si-phases), ubiquitous in nature will be presented.