PhD students of the Department of Applied Natural Sciences

Research has a long tradition in the Department of Applied Natural Sciences. In the following, we give a small insight into the variety of topics covered by the research work of our doctoral students and list by whom they are supervised at H-BRS. Further links lead to research institutes, cooperation partners, publications, etc. (Selection, last update February 2024).

Patrick Babczyk
PhD student Patrick Babczyk is investigating the influence of secreted extracellular vesicles (exosomes) from stem cells differentiating towards fat cells on endothelial cells. These are cells that form the inner layer of blood vessels. He hopes to find a starting point for preventing the development of atherosclerosis, the pathological narrowing of arteries, and the associated consequences such as heart attack or stroke.
Supervisor: Prof. Dr. Edda Tobiasch

Jonas Bergrath, TREE

In the course of the sustainable rethinking, it is enormously important to obtain chemical resources primarily from renewable raw materials. One possible candidate that can also be used in the long term in a wide variety of preliminary stages in the chemical industry is lignin. To this end, doctoral student Jonas Bergrath is looking at various biogenic wastes (including waste wood and pomace from winegrowing) in order to isolate lignin in as "green" a way as possible. Since lignin is extremely difficult to reproduce, he uses a wide range of analytical and computational chemistry methods to reveal possible structure-property correlations. The overall goal is to relate the physico-chemical properties (including adsorption and behaviour in solvents) to structural elements of lignin and to use it as an adsorbent for organic small molecules (e.g. pharmaceuticals) in wastewater treatment.
Supervision: Prof. Dr. Margit Schulze

Jennifer Braun, ISF
PhD student Jennifer Braun takes a closer look at the sniffer dog as a "detector" for volatile organic compounds (VOCs). Due to their highly sensitive olfactory organ, sniffer dogs have the special ability to sniff drugs, explosives, humans or animals by means of their scent. But how sensitive is the dog and how reliable is its detection? To get to the bottom of this question, PhD student Jennifer Braun is working on methods for the quality-assured quantification of VOCs, which primarily involve instrumental analysis but also the sniffer dog. Supervisor: Prof. Dr. Peter-Michael Kaul

Rene Breuch, ISF
Unwanted bacteria in the food industry are a problem, and detecting them is a particular challenge. PhD student Rene Breuch is investigating how surface-enhancing Raman spectroscopy (SERS) can be used to detect such bacteria in time. In doing so, he detects and differentiates spoilage bacteria through the targeted development of durable SERS substrates based on gold nanoparticles, suitable sampling methods and multivariate statistics.
Supervisor: Prof. Dr. Peter Kaul.

Dominik Büchner,  TREE, Projekt Hybrid-KEM
Biocompatible, synthetic bone replacement materials are a good alternative to the patient's own bone tissue, as they show fewer rejection reactions, are available in large quantities and can be modified if necessary. In the Hybrid KEM project, doctoral student Dominik Büchner is developing a novel bone substitute material that comes as close as possible to natural bone and is also therapeutically active. To this end, he is optimizing the synthesis of the bone mineral hydroxyapatite and chemically modifying polysaccharides derived from algae with bisphosphonate agents, which are used for bone regeneration.
Supervisor: Prof. Dr. Margit Schulze.

Xuan Tung Do, TREE, Projekt BiopolymerModell
Doctoral student Xuan Tung Do is investigating how to turn a centuries-old waste product into a material with superpowers. Many objects of daily life are still produced in some form from fossil raw materials such as crude oil. Since these raw materials are only available in limited quantities, scientists are looking for sustainable alternatives. To this end, doctoral student Xuan Tung Do is investigating a waste material from the paper industry - lignin. It is a complex biopolymer and must first be characterised using different analytical and statistical methods before it can be used as a direct substitute for crude oil. As part of his doctoral thesis, Do determines the molecular weight of the biopolymer using different spectroscopic as well as 1D and 2D chromatographic methods.
Supervisor: Prof. Dr. Margit Schulze.

Benedikt Eger
Lead dioxide is a proven anode material in electrochemistry due to its corrion resistance, low material costs and comparatively high conductivity. Doctoral student Benedikt Eger is working on its application in electrolytic water splitting. In this process, in addition to the cathode-side hydrogen and the anode-side product oxygen, the strong oxidant ozone is also produced. In the oxidative purification of wastewater, ozone is used to decompose contaminants and pathogens into ideally harmless or more easily removable products; residual ozone reacts to form oxygen.
However, for large-scale applications, one problem with ozone generation at PbO2 anodes is apparent: efficiency. The efficiency for electrochemical ozone generation corresponds to the ratio of the amount of ozone generated to the maximum amount of ozone that can be generated according to Faraday's equation. In order to generate ozone more cost-effectively by means of electrolysis, a targeted increase in efficiency is necessary.
Benedikt Eger wants to develop a new model for the relationship between the properties of lead dioxide layers and the process of electrolytic water splitting as part of his doctoral thesis and use it to increase the efficiency of ozone formation.
Supervisor: Prof. Dr. Steffen Witzleben

Philipp Gillemot, TREE, Projekt REDEX
High-quality drinking water is one of the most widely used resources in industry, agriculture and private households. However, the wastewater produced during use requires complex treatment, as it can be contaminated by a wide range of chemicals. In order to break down potentially harmful contaminants, so-called oxidation processes are widely used in sewage treatment plants. However, certain compounds, including pesticides and drug residues, are very stable and cannot be broken down by oxidative means - they remain persistent in the environment. Therefore, doctoral student Philipp Gillemot is investigating to what extent the reductive treatment of contaminated water can be used as an efficient alternative to render such critical water constituents harmless. One focus is on the development of suitable catalyst materials in order to fully exploit the potential of this novel treatment method.
Supervisor: Prof. Dr. Steffen Witzleben

Nektaria Giotis
Doctoral student Nektaria Giotis researches a rare genetic metabolic disorder, the HSD10 defect, which was first identified in 2000. Under the supervision of Prof. Dr. Thomas Lücke of the Ruhr-University Bochum and Prof. Dr. Jörn Oliver Sass of the H-BRS she is working on a medical doctoral project. The aim is to obtain information on the course of the disease and on the relationship between genotype and phenotype, and to investigate possible influences on the steroid balance. Thus, Nektaria Giotis contributes to a better understanding of HSD10 disease and helps to improve diagnosis and prognosis.
Supervisor: Prof. Dr. Jörn Oliver Sass

Roman Grimmig, TREE, OzonArray, ReDeX
It is an absolute matter of course for us that we get water of perfect quality from the tap. In the context of drinking water treatment, oxidative processes such as ozonation are often used, which effectively remove potentially harmful water constituents (e.g. germs) and thus disinfect the water. For this purpose, PhD student Roman Grimmig is developing a modular ozone generator that enables this oxidative treatment option to be tailored to the specific requirements. In order to be able to reliably exclude undesirable disinfection by-products arising in the process, a combined oxidative and reductive treatment in conventional tap water is being evaluated.
Supervisor: Prof. Dr. Steffen Witzleben

Jana Hinz, ISF
N-nitrosamines are partly highly volatile compounds that can be formed in many different industrial processes and are classified as carcinogenic. Due to their high health risk, it is of acute interest to develop reliable, sensitive and mobile systems for the detection and quantification of N-nitrosamines. PhD student Jana Hinz is working on the development of a GC-FAIMS system, a measuring device for the rapid analysis of N-nitrosamines. This system is to be applied in various branches of industry. Compared to common methods, the GC-FAIMS offers the advantage of being fast, field applicable and cost efficient.
Supervisor: Prof. Dr. Michaela Wirtz

Lil Klaas
Doctoral student Lil Klaas, with the support of the Association for Pediatric Metabolic Disorders (APS), is investigating rare genetic defects in selected enzymes (aminoacylases) that lead to congenital metabolic disorders. The aim of her research is to gain a better understanding of the mechanisms underlying such disorders and thereby create a basis for therapeutic approaches. Lil Klaas is a fellow of the Equal Opportunities Office and conducts research at the H-BRS site in Rheinbach.
Supvervisor: Prof. Dr. Jörn Oliver Sass

Rene Yufenyuy Lawong
One of the key elements utilized by tetrapod vertebrates to accomplish their sodium and water balance  is the epithelial sodium channel (ENaC). This is a heterotrimeric ion channel that fine-tunes the reabsorption of sodium ions from pre-urine in the aldosterone-sensitive distal nephron, matching dietary sodium intake to its excretion. ENaC also mediates sodium absorption across epithelia of the colon, sweat ducts, reproductive tract and lung. Improper regulation of ENaC is associated with severe human disease such as pseudohypoaldosteronism type 1, Liddle syndrome, nephrotic syndrome, cystic fibrosis and pulmonary oedema. PhD student Rene Yufenyuy Lawong is investigating the various mechanisms through which this ion channel is regulated. A special emphasis lies on the investigation of the physiology of different ENaC-subunit assemblies which result in functionally distinct ENaC isoforms. 
Supervision: Prof. Dr. Mike Althaus 

Dennis Michalski 

Pyrotechnic delay elements are used in blasting technology, fire extinguishing systems and fireworks, for example. They often contain toxic heavy metal compounds. Their processing requires binders, which are associated with the use of solvents or the need for drying processes. This results in solvent waste or a high energy requirement. The conventional production of retarding sets also requires the use of expensive equipment, which is an important economic factor. The aim of Dennis Michalski's doctoral project is  to develop an alternative production method for retarder sets, to replace toxic compounds and to use more environmentally friendly binders. The retarding sets are being examined, for example, with regard to their burn-off speed and the associated influencing factors. The development is based on the 12 rules of green chemistry (Anastas & Werner) and implements them wherever possible.

Supervision: Prof. Dr. Peter Kaul, Prof. Dr. Claudia Wickleder

Cassandra Moers, TREE
PhD student Cassandra Moers researches aluminium thick wires that are processed in a variety of electronic components, for example in sensors and control units of means of transport. Such electronic components are becoming increasingly important in the context of e-mobility and "assisted and autonomous driving". In daily use, aluminium thick wires are exposed to mechanical, thermal and electrical stresses and can fail over time, which can lead to a complete failure of the component. Therefore, doctoral student Cassandra Moers investigates and evaluates the reliability of the wire materials and simulates their application behaviour. The aluminum thick wires she is investigating have diameters of less than half a millimeter, which is about ten times thicker than a human hair.
Supervisor: Prof. Dr. Christian Dresbach
 

Matthias Muhr, ISF
Newly synthesized chemicals or products that pose an explosion hazard in pure form or as a mixture pose a safety risk if they are not sufficiently characterized and classified. Classically, such substances are characterized with a variety of conventional test methods that require the handling of relatively large sample quantities. The aim of Matthias Muhr's PhD project is to develop a test apparatus by sensory monitoring of these conventional methods, with which it is possible to carry out a more precise characterization of such substances. In doing so, the sample quantities are to be significantly reduced in order to significantly lower the safety risk during handling.
Since 2019, Matthias Muhr is a scholarshipholder of the Institute of Safety and Security Research. 
Supervisor: Prof. Dr. Gerhard Holl

Lukas Pschyklenk, Natural Sciences/ISF, Project "Optospin"
Liquid crystals are generally only known from displays (LCD). The extraordinary optical properties of these fascinating substances can be used for various applications. One of them is gas sensor technology. A special liquid crystalline phase, which is created by doping with optically active substances, reflects only a narrow wavelength range of the incident light back, similar to the wings of a butterfly. For the observer, the liquid crystal then appears in a very intense color. However, no dye is responsible for the color, only the structure of the liquid crystal. Through a chemical reaction of the dopant with a substance to be detected, this structure changes and with it the visible color immediately. For the detection of substances, PhD student Lukas Pschyklenk is developing a gas sensor that has no power consumption and can be read with the naked eye. The PhD project is linked to the BMBF project OptoSpin. The aim of the project is to find suitable dopants for selected safety-relevant substances and to improve the applicability of these sensors.
Supervisor: Prof. Dr. Peter Kaul

Julian Rech, TREE
Plastics have become an integral part of everyday life. In order to improve the mechanical properties of plastics and thus extend the range of applications, plastics are reinforced with fillers, for example with glass fibres, glass beads, carbon fibres etc. Doctoral student Julian Rech wants to model and verify the new mechanical properties of the resulting composite material in his research work. The new development of this model approach (Elementary Volume Concept) is based on the consideration of the adhesion between filler and matrix (plastic), which results in a better prediction of e.g. the stiffness of the composite material. These model results are important for designers and engineers for the construction of new plastic components for e.g. automotive, aerospace and safety related applications.
Supervisor: Prof. Dr. Bernhard Möginger
 

Hanna Rohde
In her dissertation, chemist Hanna Rohde evaluates the service life of metal-ceramic substrates for power electronics. These are used, for example, in the automotive industry, in aviation and in the energy sector. As a materials scientist, she wants to develop a numerical model in order to be able to calculate the failure of the components. This should speed up the testing and approval of the modules.
Supervision: Prof. Dr. Christian Dresbach

Sara Schäfer, ISF
Due to its unique properties, ultrapure water serves as solvent or starting product for pharmaceuticals and is used to clean surfaces in the production of high-precision components in semiconductor manufacturing. Water quality monitoring is of utmost importance. For this reason PhD student Sara Schäfer develops an universal measuring instrument for quality monitoring of ultrapure water. It combines two standard methods of oxidation. The oxidation is performed by ozonation in combination with UV radiation. That leads to an advanced oxidation process and a significant increase in the oxidation power compared to conventional systems.
Supervisor: Prof. Dr. Peter Kaul

Sarah Shoushrah

What can't be cured must be endured, however, researchers are trying to change this fact and are aiming to improve and provide new treatment options for a variety of different diseases. One of these diseases are large, so-called “critical size” bone injuries, which cannot heal in the life span of an individual without extensive interventions. One approach to change this is using mesenchymal stem cells (MSCs) which have shown a great potential for treatment of such conditions. They can differentiate into bone cells and release therapeutic factors in addition. Under specific circumstances however, they can be limited in quantity and they cannot retain their abilities during prolonged lab culture. Recently, the discovery of induced pluripotent stem cells (iPSCs), for which the Nobel Prize was given in 2012, offered a new approach. These cells can be generated into mesenchymal stem cells (iMSCs) in the lab on-demand and are thus providing a possible alternative technique. iMSCs have similarities to MSCs but still little is known about them. In this project, Sarah Shoushrah will discern how similar and effective iMSCs are in comparison to MSCs for future applications in bone repair.
Supervision : Prof. Dr. Edda Tobiasch

Michael Stotter, IZNE
The German-Dutch project called "Food Protects" aims to reduce regional and surplus existing nitrate inputs from agriculture and to increase structural diversity in the agricultural landscape. To this end, PhD student Michael Stotter is working on the environmental impacts of the use of Miscanthus biomass in livestock farming. He focuses on the application of organic fertilizers from Miscanthus additions in an environmentally friendly and site-appropriate manner. The influence on the nitrogen and carbon dynamics and the interaction in the soil-plant system are in the foreground.
Supervisor: Prof. Dr. Martin Hamer

Emre Ünal

The local and controlled initiation of energetic materials by laser radiation coupled with sensory monitoring involves a number of issues and is particularly challenging for ignition materials. The direction of the work is in the area of detection methodology. Here, the controlled coupling of energy by laser radiation (different beam sources) into the investigated substances without knowledge of their specific absorption coefficients is of great interest in the development of detection methods. One way of doing this is the application of suitable coatings with known absorption coefficients.
For this purpose, different methods (e.g. spray coating) are being comparatively investigated. Thus, in conjunction with the selection of suitable laser parameters, the realization of a controlled local initiation below critical geometries could be achieved, so that the energetic material does not come to the mass for conversion, thus preventing detonation or deflagration. The gases and physical phenomena emitted during the reaction are used to study the material under investigation and the processes occurring here.
Supervisor: Prof. Dr. Thomas M. Klapötke / Prof. Dr. Peter Kaul

Sarah Vermeeren, ISF
PhD student Sarah Vermeeren is developing a method for the detection of wart disease, which is caused by the potted fungus Synchytrium endobioticum (Schilb.) Perc. and is one of the most important pests of potatoes. It even has quarantine status in EU countries, i.e. infected areas are closed to potato cultivation for years. Early detection and containment of wart disease is therefore extremely important. Sarah Vermeeren uses thermodesorption gas chromatography-mass spectrometry (TD-GC-MS) and proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) to analyse the Volatile Organic Compound (VOC) profiles of potato plants, potatoes and residual soils with the aim of differentiating between healthy and infected status.
Supervisor: Prof. Dr. Peter Kaul

Johannes Warmer, ISF
In his doctoral thesis, Johannes Warmer is working on the development of a sensor system for the detection of triacetone triperoxide (TATP), a highly explosive substance that has been used by terrorists for several attacks. In his work he is mainly concerned with so-called metal oxide semiconductor gas sensors, which are characterized by a very high sensitivity but low selectivity at low acquisition costs. In order to compensate for the disadvantage of low selectivity, the sensor performance has to be optimized by selecting suitable materials and operating modes of the sensor. Within the scope of the doctoral thesis, starting with the production of the actual sensor, the development of suitable signal processing strategies and the combination of different spectroscopic and electrical measuring methods are used to not only realize the suitability of such a sensor system, but also to formulate the underlying chemical surface reactions. The aim is to gain a deeper understanding of the actual sensory mechanism.
Supervisor: Prof. Dr. Peter Kaul