Newsportal - Ruhr-Universität Bochum

In the framework of this project we propose the study of (α,γ) reactions relevant to the astrophysics p-process nucleosynthesis. Specifically, we are aiming to the experimental and theoretical investigation at astrophysical beam energies selected (α,γ) reactions, such as: 73Ge(α,γ)77Se and 102Pd(α,γ)106Cd. The goal of the study, is by using the 4π NaI(Tl) detector to provide experimental data in previously unexplored energy regions or in beam energies were the existing experimental information is insufficient for setting firm constrains of the theoretical model calculations. Accordingly, we suggest the study of the excitation function of the above mentioned reactions for α-beam energies between 6-15 MeV, as provided by Dynamitron Tandem Laboratorium (DTL) of the Ruhr-Universität Bochum and by adopting an energy step of the order of 0.5 MeV.

Development of a stable and reproducible protocol for 10x Cryo-ExM on single cells. This will include a stable gel matrix as well as a solid way to measure the expansion factor and spatial distortion in 3D.

We will quantify uptake rates of radioisotopes of various mineral nutrients and/or their toxic analogues into roots of Arabidopsis or into plant gene-expressing cells. We will measure the incorporation of radiolabelled organic and inorganic substrates into endogenous metabolites and/or macromolecules of plant cells, organs and/or cells of heterologous expression systems. We will localize various elements of interest in sections of plant tissues by imaging using Particle Induced X-Ray Emission (PIXE) combined with Rutherford Backscattering Spectrometry (RBS) comparatively between wild type and mutant/transgenic plants. We will conduct live cell imaging of plant cells expressing suitably marker proteins using the Olympus IX 81 live cell imaging microscope with the goal of determining protein localization and its dynamics. It is possible that it might be necessary to apply STED super-resolution fluorescence imaging to answer our research questions.

14C-labelled substrates or nutrients and combinations will be added to the moist soil samples after a 7-day pre-incubation period. The incubation will be conducted in a CarbO2Bot® instrument which allows temperature control and records CO2 evolution from the samples through changes in electric conductivity in an alkaline solution. After certain time intervals, the solution is replaced by a fresh one and the evolved 14CO2 is determined in a scintillation counter (Perkin Elmer Tri-Carb 2800 TR). In this way, the substrate-borne CO2 can be differentiated from the SOC-borne CO2 and priming effects are calculated by subtracting the CO2 evolved from an unsupplemented control sample (Hamer and Marschner 2005). Enzyme activities will be determined in soil suspensions to which fluorogenic substrates (MUF, AMC) are added in a 96 well microplate assay as described by Marx et al.(2001).

We investigate bacterial iron acquisition, the role of siderophores, and the role of ionophores.

We use pulse-labeling to investigate the proteins newly synthesized in response to stress, e.g. antibiotic treatment.

ATPases are integral membrane proteins that play a pivotal role in cell homeostasis by pumping substrates as diverse as ions and lipids. Although several members of this group are well-studied, many molecular details involved in their working mechanism and regulation on the molecular level still remain unsolved. In combination with transporter mutants we expect to gain a molecular understanding of how ATP, pH, the ion concentration, and the lipid environment regulate these transporters.

The application of Ion Beam Analysis techniques (IBA) necessitates the availability of reliable differential cross-section data for the nuclear reactions or elastic scattering utilized. However, this is not always the case. An important lack or even complete absence of data on differential cross sections exists in several cases, limiting the applicability of IBA techniques. In the framework of this project, we conduct measurements for the determination of coherent differential cross-section datasets with proton and 3He beams. A dedicated experimental setup consisting of 6 Silicon Surface Barrier (SSB) detectors allows the simultaneous measurement of six different detection angles in energy ranges suitable for Ion Beam Analysis applications. In addition, we perform benchmarking experiments in order to verify the validity of the experimental datasets obtained.

Advanced practical experiments at the accelerators for students from the Ruhr University Bochum and Paderborn University.

This project aims a combining a Stimulated Emission Depletion (STED) and a Scanning Ion Conductance Microscope (SICM) to allow simultaneous, correlated recording of the cellular topography and a protein distribution in living cells with diffraction-unlimited resolution.

Among the processes responsible for the nucleosynthesis of isotopes heavier than iron is the so-called p process, a nucleosynthetic mechanism involving a certain class of 35 proton-rich nuclei known as p nuclei. To date, the abundances of these nuclei have been observed only in the solar system. Therefore, explaining the origin of these abundances and reproducing them within certain astrophysical scenarios helps in understanding the creation mechanism of the solar system. Astrophysical models aiming to reproduce the p-nuclei abundances in the solar system rely on the Hauser-Feshbach (HF) theory to solve a vast network of nuclear reactions relevant to p-process nucleosynthesis. Thus, in addition to any uncertainties in the astrophysical modeling, validating the predictions of the HF theory is also crucial. This validation is the goal of our research activities. In this context, the Demokritos Nuclear Astrophysics Group has been systematically measuring the cross-sections of proton- and alpha-particle-induced capture reactions at the RUBION Dynamitron accelerator using the 4π NaI summing detector since 2003. To date, more than 30 nuclear reactions have been investigated.

Detailed knowledge from particle physics experiments will be used to study in-situ the behaviour of particles and gases in bulk reactors. γ rays from a positron annihilation will be used in a PET-like configuration taking advantage of developments of most-modern particle physics detectors. The advantage of PET lies in the fact that it is a non-invasive technology that allows to study the behaviour of systems in a closed containment densely packed with spheres. While PET technology is often used in medical applications, we will use bulk spheres and gases marked with radioactive positron sources and PET to study the transport of those spheres and gases in bulk solids reactors

In the department RUBION ion-beams, in the area of the industrial implantation, ion irradiations in the MeV range are carried out on behalf of customers in cooperation with our partner, the rubitec GmbH. There is a wide range of different ions available. The available energy and dose range depends on the respective species and the wafer size of our customers. The possibilities are determined by us depending on the application for each customer on request. In this field we are certified according to DIN EN ISO 9001: 2015 !

The work includes material development and structural Layering of perovskite for electroluminescence and laser applications. Different layer formation procedures such as pure liquid phase processes, pure vacuum deposition, as well as hybrid deposition processes are demonstrated. The work aims to study and optimize luminescence quantum efficiency and optical amplification and to understand the relationship between composition / structure and optical amplification. And then, selected materials are integrated into electroluminescent devices.

Boron (81.1% 11B and 19.9% 10B) and lithium (92.5% 7Li and 7.5% 6Li), two of the lightest elements in nature, are widely used in many technological as well as industrial applications. As a result, their detection and accurate depth profile determination, via Ion Beam Analysis (IBA) techniques, is important. Nuclear Reaction Analysis (NRA) constitutes the most effective of such techniques, as it results in isolated peaks (due to the generally high Q-values) with negligible background and also provides the possibility for simultaneous analysis of several low Z elements in near-surface layers of materials. The use of the NRA technique is further enhanced when the light elements under study co-exist in complex matrices. Especially, when these techniques are performed at projectile energies in the 100 keV – 300 keV range (Medium Energy Ion Scattering technique – MEIS), additional advantages are offered. More precisely, due to the limited penetration of low energy protons in matter, MEIS is highly sensitive to the surface layers of a sample, reaching depth resolutions on the order of a few nanometers. However, there is a significant lack of differential cross section datasets, not only for low proton energies but also over a wide range of backscatter detection angles. The aim of the present work is to enrich the literature by providing reliable differential cross-section data in this uncovered area. For that reason, the 11B(p, a0)8Be and 6Li(p, 3He)4He reactions were thoroughly studied in a wider energy and angular range. The experiments will be conducted at the 4MV Dynamitron Tandem Laboratory of the Central Unit for Ion Beams and Radionuclides (RUBION) of the Ruhr University Bochum in Germany. For proton energies of 150 keV up to 340 keV the 500 kV single-stage accelerator will be used, with the measurements being extended up to 1000 keV at the 4 MV Dynamitron Tandem accelerator. The energy step varies from 2 keV to 20 keV. For the detection of the charged particles, three Silicon Surface Barrier (SSB) detectors will be placed at the angles of 130°, 140° and 160° and two Passivated Implanted Planar Silicon (PIPS) detectors at 150° and 170°. Two different targets will be used for the two reactions under study. A thin 6LiF (95 % 6Li & 5% 7Li) layer evaporated on a natC substrate, while the second one is a natB thin layer, evaporated on a natCu substrate, with a top layer of Au.

Metallic thin films with film thicknesses of typically less than 50 nm are fabricated by electron beam deposition, either as a planar film or as a patterned film using lithography techniques. Film thicknesses of planar films are typically measured using a quartz microbalance, which requires an independent and absolute calibration for each deposited elemental species. The amount of metal actually deposited through a lithography mask containing nanometric mask openings may depend on the clogging behaviour of the mask employed, which again means that there is a need for an absolute determination of the amount of deposited material. Last but not least deposited thin films and nanoobjects may be subjected to dewetting phenomena, which are often not well studied and require analytical techniques for their quantification. In many cases these goals can be achieved with unrivaled accuracy by RBS with He ion beams at 1.5 - 2.0 MeV. Occasionally, supporting information by XPS may be necessary.

This practical lab course is part of the Master studies of Biochemistry and iSTEM.

In vitro transcription with radioactive labeling

In the area of ion beam analysis, RUBION provides a variety of methods that are used to examine the composition of materials. Established methods include RBS, NRRA, D-NRA, EBS and PIXE. On the one hand, this project aims to guarantee the reliable use of methods. This involves ensuring that the respective measurement systems are ready for use and that the analyses provide reliable results for scientific applications. In addition, this project focuses on the optimisation and automation of existing methods. These include, for example, improving measurement accuracy, using accelerator beamtimes more efficiently, or reducing the effort required to analyze data. Finally, under this project, existing or new requirements may result in further method development as required.

This "project" covers a conglomerate of activities that entail the use of infrastructure of the Bandow lab that is located at RUBION, but does not entail work with unstable isotopes.

Using radiolabeled precursors in incorporation experiments, we analyze the antibacterial mechanism of action.

PIXE technique is applied for the qualitative and quantitative analysis of major and trace elements in various kinds of samples, such as in minerals, glasses, alloys etc. The concentrations of elements from Si up to U can be determined in samples of different structures, i.e. in homogeneous thin or thick samples, as well as in layered ones. The sensitivity of PIXE can reach levels of the order of a few parts per million (ppm).

VO2 is of interest due to its Semiconductor-to-Metal phase transition. Elmental addition can modulate the transition properties of VO2. To systematically study the effect of elemental doping, V-M-O thin film libraries with continuous composition spread are fabricated by magnetron reactive co-sputtering. The concentration of dopant (M) will be determined by Rutherford backscattering spectrometry (RBS). In addition, it has been reported that the stoichiometry of VOx, e.g., the ratio of oxygen to the metals, can also influence the transition properties. To estimate the amount of oxygen, Nuclear reaction analysis (NRA) will be performed on the libraries.

The project aims at the realization of single photon sources in the telecom wavelength regime, based on single rare-earth ions (like erbium or ytterbium) precisely doped into optical crystals by means of ion implantation (up to 200nm below the surface). The main advantage of the proposed single photon sources are their true single photon emission, their fourier-limited linewidth and the ability to store emitted photons directly in a medium based on rare-earth ions (straight forward interfacing). The typically low fluorescent signal of single erbium/ytterbium ions can be boosted by orders of magnitude through coupling them to optical resonators (fabricated from thin film lithium niobate) with high Q factors. The single photon source behaviour will be assessed by the indistinguishability of the emitted photons in a Hong-Ou-Mandel experiment.

We are investigating the high energy ions (H, C...) implantation into silicate minerals.

The biogenesis of photosynthetic protein complexes of the chloroplast thylakoid membrane requires highly specific protein sorting, integration and assembly mechanisms of nucleus as well as plastid encoded subunits. Central steps in the biogenesis of photosystem II (PS II) are the cotranslational insertion of the plastid encoded D1 protein into the thylakoid membrane and its subsequent assembly into functional PS II. We recently established a technique to partially reconstitute the cotranslational insertion of [35S]-D1 using a homologous in vitro translation system derived from pea chloroplasts. The aims of this proposal are (I) to identify novel components involved in cotranslational protein insertion in thylakoid membranes, (II) to dissect the protein contacts of the nascent D1 chain during translation and insertion and (III) to get insight into the mechanisms underlying targeting and attachment of ribosome-nascent chain complexes to the thylakoid membrane.

This project is dedicated to the thin film analysis of selected materials prepared by using the process integrating cluster tool of the ForLab PICT2DES. Ultrathin dielectric, metallic and semiconducting films prepared via (PE)ALD are investigated, here the focus is on 2D materials. The films are characterized with ion and X-rays to gain insight into the influence of process parameters on the film composition.

Oligodendrocytes are responsible for myelination in the nervous system thereby enabling faster action potential propagation. Their progenitors (OPCs) migrate from the subventricular zone towards their target cells and are able to renew or repair myelin sheets. A disruption may lead to unmyelinated axons in the nervous system, which is a typical symptom of multiple sclerosis. Greater knowledge of the dynamics of the growth-cone-like structures on OPC might shed more light on the migration and movement mechanisms of OPCs. Using super-resolution microscopy techniques, the dynamics of the tips will be further investigated.

ABSTRACT (1400ch): Neutrons play a crucial role in the understanding of hydrogen sorption and dynamics in advanced catalyst materials. In this project we want to help understand how different activation strategies impact the chemical bonds and dynamics of hydrogen in MoS2 catalyst powders, one of the most promising candidates for replacing Pt in the production of green hydrogen. In a previous ILL PhD project we have made substantial progress in the identification of chemical processes and dynamics of hydrogen in MoS2 single crystals, which will allow us to classify motion observed on powders, where we expect to see much more complex dynamics. The PhD work will be centred on neutron research, but in view of the complexity of the chemistry involved, it will be essential that we combine the neutron scattering with several analysis techniques including electrochemical methods, X-ray scattering and photoelectron spectroscopy as well as ion beam techniques.

This long-term project aims at developing and optimizing our STED and SICM instrument.

This project uses high spatial resolution measurement of concentration gradients in natural and experimentally produced samples of minerals and rocks. The gradients are then modeled to understand the mechanism of material transport in mineralogical systems. The information is used to develop methods to determine the timescales on which various geological (e.g. volcanism, mountain building) and planetary (e.g. cooling rate in meteorite parent bodies such as asteroids) processes operate.