Ion transport in electrolyte and polyelectrolyte systems

Electrodialysis and other electromembrane processes have been researched for decades. However, not all fundamental mechanisms of charge-selective membranes and their interfaces have been understood. This thesis aims to increase the understanding of some of the processes happening at and around these interfaces by eliminating the electroneutrality condition from the set of commonly assumed simplifications. Multiple layers, reactions and convection are considered in combination with diffusion and electromigration. The complex set of equationsis shown to be tractable by computational methods. The thesis discusses a computational framework and tackles various problems not easily accessible by commercial software. A fundamental study of the common assumption of the ideal bulk boundary condition with an artificial mixing model reveals a deviation in dynamic settings, demonstrated by an increase in the depletion time of the boundary layer under limiting current density. Layer-by-Layer membrane assemblies are investigated under steady-state conditions and their impedance in asymmetric salt solutions is highlighted, showing that a single systemic capacitance may yield multiple characteristic frequencies. Bipolar membranes are investigated towards their behaviour at the junction in a reactive electrolyte under various conditions. Using the same model, weak dissociating salts are studied. Weak dissociating acids and bases play a major role in biological systems and their purification is a major issue in process engineering. Leveraging the charge mechanics of the computational framework, nanofiltration of Itaconic acid is investigated and the capability to predict complex pH dependent systems is demonstrated

Autologes plättchenreiches Plasma und Gentamycin zur Behandlung der Osteomyelitis im Gesicht: Ein vielversprechender, biologischer Therapieansatz

Einleitung: Plättchenreiches Plasma (PRP) enthält zahlreiche Zytokine, die in Wundheilungsprozessen involviert sind und entzündungshemmend wirken. Zudem enthält es immunkompetente Zellen, die sogar Infektionen bekämpfen. Eine Osteomyelitis stellt ein schweres und oft nur invasiv zu therapierendes Krankheitsbild dar. Bei ausgeprägter Ausdehnung und fehlendem Ansprechen auf konservative Therapie ist radikale chirurgische Sanierung erforderlich, die insbesondere bei Lokalisation im Gesicht zur kosmetischen Entstellung des Patienten führt. Aus diesem Grund stellen biologische Ansätze, die solch fulminante Verläufe therapieren können, eine wesentliche Alternative dar. Ziel dieser Studie war daher die Kombination von Gentamycin mit PRP zur lokalen Anwendung bei Osteomyelitis im Gesicht, in Fällen, in denen die alleinige Therapie (systemisch und lokal) mit Gentamycin nicht erfolgreich war.Methoden: Drei Patienten mit behandlungsresistenter Osteomyelitis im Bereich des Oberkiefers, des Nasenbeins bzw. des Stirnbeins wurden nach Debridment des nekrotischen Gewebes mit autologem aktiviertem PRP und Gentamycin behandelt. Dieses Gemisch wurde lokal wöchentlich für einen Zeitraum von 6 Wochen verabreicht. Ergebnisse: Alle Patienten berichteten über eine Schmerz- und Schwellungsreduktion bereits nach der zweiten Anwendung. Eine radiologische Kontrolle erfolgte mittels digitaler Volumentomographie nach der letzten Behandlung und zeigte eine Wiederherstellung der trabekulären und kortikalen Strukturen des Knochens ohne periostale Anreicherung. Sechs Monaten nach Abschluss der Therapie traten keine erneuten Beschwerden auf.Zusammenfassung: Aktiviertes PRP in Kombination mit Gentamycin ist eine vielversprechende Therapieoption für die Behandlung einer therapieresistenten Osteomyelitis.Der Erstautor gibt keinen Interessenkonflikt an

Coupled Ionic–Electronic Charge Transport in Organic Neuromorphic Devices

Conductive polymer devices with tunable resistance allow low-energy, linear programming for efficient neuromorphic computing. Depolarizing impurities, however, are difficult to exclude and limit device performance through nonideal writes and self-discharge. It is shown that these phenomena can be numerically described by combining two-phase charge transport models with electrochemical self-discharge. The simulations accurately reproduce the experimental data, including cyclic voltammetry and standard neuromorphic functions, such as linear programming of discrete states and short-term potentiation. Impurities affect device write accuracy significantly for long programming times above 1000 ms. The effect is reduced to 0.03% for shorter times. Self-discharge is impacted by device potential as well as impurity concentration. A model-based trade-off between operating parameters nearly triples the number of usable conductance states at ambient conditions. Understanding these device limitations as well as workarounds is a vital step toward the implementation of neuromorphic device networks

Hands-on Kinetic Measurements and Simulation for Chemical Process Engineering Students

Hands-on experience in the laboratory is essential in chemical engineering education to enhance the understanding of abstract theories and their effect on chemical processes. In this work, we describe a laboratory class, which combines some of the main engineering concepts into a set of hands-on experiments and simulations. Students are introduced to an iodine clock reaction performed in multiple different reactor types and are instructed to determine the reaction kinetics. Subsequent analysis of the experimental data in Python teaches basic programming skills and the concepts of numeric integration and optimization. Finally, a digital twin of one of the reactors is developed in COMSOL Multiphysics to give the students an application-focused introduction to more-dimensional multiphysics modeling. The students thereby get practical insights into the different methods and stages of reactor and reaction engineering. Based on the students' assignments, we consistently see a deeper understanding of reaction kinetics and reactor engineering than in the accompanying traditional lecture