Die Fähigkeit künstlicher Mikroschwimmer, auf äußere Reize zu reagieren und deren mechanistische Ursprünge, gehören zu den umstrittensten Fragen der interdisziplinären Wissenschaft. Die Erzeugung chemischer Gradienten ist dabei eine technische Herausforderung, da sie aufgrund von Diffusion schnell abflachen. Inspiriert von ‘Stop-flow’ Experimenten aus der chemischen Kinetik zeigen wir, dass die Erzeugung eines mikrofluidischen Gradienten durch Kombination mit einer Druckrückkopplungsschleife zur präzisen Kontrolle des Stoppens erfolgen kann. Das ermöglicht es uns, die mechanistischen Details der Chemotaxis von künstlichen katalytischen Janus-Mikromotoren zu untersuchen. Wir stellen fest, dass diese Kupfer-Janus-Partikel eine chemotaktische Bewegung entlang des Konzentrationsgradienten sowohl in positiver als auch in negativer Richtung zeigen, und wir demonstrieren die mechanische Reaktion der Partikel auf unausgewogene Widerstandskräfte, die dieses Verhalten erklären.

Die atomgenaue Synthese von helikalen mehrschichtigen Nanographenen (NG) neuer Topologie ist aufgrund ihrer exotischen physikochemischen Eigenschaften von substanziellem Interesse. Allerdings ist die Synthese dieser Nanographene, speziell mit nicht benzoiden Ringen, äußerst herausfordernd. Wir präsentieren in diesem Artikel die effiziente Synthese des ersten helikalen zweischichtigen nichtbenzoiden Nanographens (HBNG1) ausgehend von einem maßgeschneiderten Azulen-Vorläufer, welcher bereits das neuartige Strukturelement zweier in [10]Helicen eingebetteter heptagonaler Ringe enthält. Die Einkristalldiffraktometrie gibt Einblick in die sterisch stark gespannte Doppelschichtstruktur mit einem Rekordwert für den kleinsten Interschichtabstand von nur 3.2 Å, in der Substanzklasse der doppelschichtigen Nanographene. Bemerkenswerterweise kommt es im Raum zwischen den Schichten zu π–π Wechselwirkungen. Wir untersuchten diesen Effekt durch in situ Spektroelektrochemie und Simulationen mittels Dichtefunktionaltheorie (DFT). Des Weiteren wurden die chiroptischen Eigenschaften der P/M-Enantiomere von HBNG1 durch Zirkulardichroismus und zirkular polarisierter Fluoreszenz charakterisiert.

The thesis primarily focuses on the pressure influence on the reaction rate of char gasification using laboratory thermogravimetric analysis (TGA). It discusses also the gasification of char with a mixture of gasifying agents (CO2 + steam) under a pressure of 40 bar and temperatures up to 1100°C, which has not been reported in the literature to the best of found knowledge. The first section investigates the pressure impact on char gasification kinetics by varying the total and partial pressure of the gasifying agent. The second section investigates the effect of gasifying agent at 40 bar and combining the pyrolysis step in the investigation, which was done in-situ under inert atmosphere. Then, mixtures of the two gasifying agents were used for the gasification in separate experiments. The third section uses raw coal as material and gives attention to the char structure formed after the pyrolysis under the high pressure. The fourth section includes measurements for char characteristics during the gasification reaction and compares them with the reference char data performed previously in this research group under atmospheric pressure.:Abstract 1. Introduction 1 1.1 Scope of the thesis 1 1.2 Layout of the thesis 2 2. Literature Review 4 2.1 Background 4 2.2 Coal and gasification 5 2.2.1 Coal classification and characteristics 5 2.2.2 Introduction to gasification process 7 2.2.3 Coal Analysis 10 2.2.4 Pyrolysis 13 2.2.5 Gasification reactions 13 2.2.6 Mechanism of solid-gas reaction and Thermodynamic background 14 2.2.7 Regimes of gas-Solid Reactions 17 2.2.8 Summary 19 2.3 Effect of Pressure on gasification process 20 2.3.1 Advantages of high-pressure operation 20 2.3.2 Influence on the pyrolysis step 20 2.3.3 Effect of Pressure on coal swelling 21 2.3.4 Pressure influence on char morphology 23 2.3.5 Effect of pyrolysis pressure on char surface area 23 2.3.6 Effect on reaction order n 24 2.3.7 Summary 24 2.4 Pressure influence on char gasification reaction kinetics 24 2.4.1 Pressure influence on gasification reaction kinetics 25 2.4.2 Summary 27 2.5 Char gasification using gasifying agent mixtures 27 2.5.1 Mechanism 29 2.5.2 The role of the inhibition and the catalytic effect 29 2.5.3 Summary 32 2.6 Thermodynamic aspects and the estimation of the reaction rate 32 2.6.1 Background 32 2.6.2 Basic definitions of reaction rate 34 2.6.3 Intrinsic kinetic models 35 2.6.4 Theoretical models 36 2.6.5 Empiric Models 39 2.6.6 Intrinsic kinetic models expressed by CO2 concentration 40 2.6.7 Arrhenius Activation Energy 40 2.6.8 Differentiation of a polynomial fit data (Differential method): 41 2.6.9 Summary 43 3. Experimental Analysis 44 3.1 Thermogravimetry 44 3.2 Testing of the gas volume fraction and the total pressure influence on char gasification 45 3.2.1 Testing of the gas volume fraction influence 45 3.2.2 Testing of system pressure influence on char gasification 56 3.2.3 Discussion 65 3.3 Coal gasification at 40 bar with pure CO2, H2O and their mixtures 65 3.3.1 Gasification with pure CO2 and H2O 66 3.3.2 Coal gasification using CO2 / H2O mixtures at high system pressure 87 3.3.3 Discussion 96 3.4 Pressure influence on coal gasification 100 3.4.1 Coal gasification under different system pressures 100 3.4.2 The effect of increasing pressure on coal morphology 104 3.4.3 Discussion 117 3.5 Influence of the pressure on the char properties during gasification 118 3.5.1 Discussion 129 4. General discussion 134 5. Conclusions 139 5.1 Significance of the findings 143 5.2 Recommendations 144 6. Appendix 146 6.1 Literature and Results 146 6.1.1 Conditions influence on gasification of the (a) temperature, (b) partial pressure 146 6.1.2 TGA-DMT 147 6.1.3 Testing of the gas volume fraction influence on coal gasification 148 6.1.4 Testing of system pressure influence on char gasification 150 6.1.5 Coal gasification at 40 bar with pure CO2, H2O and their mixtures 152 6.1.6 Coal gasification under different pressures 162 6.1.7 Summary of gas mixture gasification studies 167 6.2 Figures Index 169 6.3 Tables Index 175 6.4 References 177

Alumina-containing binders are widely used for the binding of catalyst particles by spray drying and calcination. As a part of the active matrix, they contribute to the catalytic performance of the resulting catalyst grain during hydrocarbon cracking. In this study, correlations are investigated using different compositions of Al- and Si-based binders (AlCl3 and colloidal silica) together with kaolin as a filler and ZSM-5 zeolite as an active compound. It was demonstrated that the conversion of a 50:50 hexane mixture, the selectivity toward unsaturated hydrocarbons, and the shape-selective conversion of the hexane feed are highly dependent on the amount and distribution of alumina in binder formulations. While silica species are distributed near the outer shell of catalyst grains, the alumina species are distributed evenly as an adhesive between the catalyst compounds ZSM-5 and kaolin. An optimum amount of alumina in binder formulations results in an increasing conversion of hydrocarbon feedstock due to optimum in active-site accessibility but only a slight decrease in shape-selective properties compared to pure ZSM-5, resulting in an optimum yield of light olefins, especially propylene.

The increasing emergence of resistances against established antibiotics is a substantial threat to human health. The discovery of new compounds with potent antibiotic activity is thus of utmost importance. Within this work, we identify strong antibiotic activity of the natural product myxocoumarin B from Stigmatella aurantiaca MYX-030 against a range of clinically relevant bacterial pathogens, including clinical isolates of MRSA. A focused library of structural analogs was synthesized to explore initial structure-activity relationships and to identify equipotent myxocoumarin derivatives devoid of the natural nitro substituent to significantly streamline synthetic access. The cytotoxicity of the myxocoumarins as well as their potential to cure bacterial infections in vivo was established using a zebrafish model system. Our results reveal the exceptional antibiotic activity of the myxocoumarin scaffold and hence its potential for the development of novel antibiotics.

We present an autonomous, chemical logic gate based on a switchable metal–organic framework (MOF) composite, containing carbon nanoparticles and a Pt catalyst. The switchable MOF composite performs as AND logic gate. Hydrogen and oxygen gas streams serve as binary inputs. Catalytically formed water induces a structural transition (crystal volume expansion) of the MOF, and as a consequence, a detectable drop in conductance of the composite as a ‘true’ output only if both gases come in contact with the composite.

Kohlenstofffasern sind aufgrund ihrer hohen massespezifischen mechanischen Belastbarkeit ein unverzichtbarer Werkstoff im Leichtbau. Diese werden mittels eines zeitaufwendigen, thermooxidativen Stabilisierungs- und eines inerten Carbonisierungsprozesses hergestellt. Bedingt durch die kommerziell dominierte Forschung basiert der Großteil der veröffentlichten Optimierungsansätze für diese Prozessschritte bis heute auf unvollständigen, empirischen oder nicht-parametrischen, datengetriebenen Modellen. In der vorliegenden Arbeit werden hybride semi-parametrische Ansätze unter Berücksichtigung der Eigenschaften des Precursorsystems und der Prozessparameter für die Modellierung des Stabilisierungsprozesses untersucht. / Carbon fibers are an indispensable material in lightweight construction due to their mass-specific mechanical load capaci-ty. These are produced by means of a time-consuming, thermo-oxidative stabilization process and an inert carbonizationprocess. Due to commercially dominated research, the majority of published optimization approaches for these processsteps to date is based on incomplete, empirical or non-parametric, data-driven models. In the present work, hybrid semi-parametric approaches considering the properties of the precursor system and the process parameters are investigated formodeling of the stabilization process.

Due to the voltage driven switching at low voltages combined with nonvolatility of the achieved polarization state, ferroelectric materials have a unique potential for low power nonvolatile electronic devices. The competitivity of such devices is hindered by compatibility issues of well-known ferroelectrics with established semiconductor technology. The discovery of ferroelectricity in hafnium oxide changed this situation. The natural application of nonvolatile devices is as a memory cell. Nonvolatile memory devices also built the basis for other applications like in-memory or neuromorphic computing. Three different basic ferroelectric devices can be constructed: ferroelectric capacitors, ferroelectric field effect transistors and ferroelectric tunneling junctions. In this article first the material science of the ferroelectricity in hafnium oxide will be summarized with a special focus on tailoring the switching characteristics towards different applications.The current status of nonvolatile ferroelectric memories then lays the ground for looking into applications like in-memory computing. Finally, a special focus will be given to showcase how the basic building blocks of spiking neural networks, the neuron and the synapse, can be realized and how they can be combined to realize neuromorphic computing systems. A summary, comparison with other technologies like resistive switching devices and an outlook completes the paper.

The biofilm-associated protein (Bap) of Staphylococcus aureus is a high molecular weight cell-wallanchored protein involved in biofilm formation, first described in bovine mastitis strains from Spain. So far, studies regarding Bap were mainly based on the Spanish strain V329 and its mutants, but no information on the genetic variability of bap-positive Staph. aureus strains is yet available in the literature. The present study investigated the molecular characteristics of 8 bap-positive Staph. aureus strains from subclinical bovine mastitis, isolated in 5 herds; somatic cell counts (SCC) of milk samples were also registered. Strains were characterised using MLST, SPA typing and microarray and the results were compared with V329. All isolates from this study and V329 were assigned to ST126, t605, but some molecular differences were observed. Only herd A and B strains harboured the genes for β-lactams resistance; the leukocidin D/E gene, a type I site-specific deoxyribonuclease subunit, 3rd locus gene and serin-protease A and B were carried by all strains, but not by V329, while serin-protease E was absent in V329 and in another isolate. Four isolates and V329 harboured the fibronectin-binding protein B gene. SCC showed the highest value in the milk sample affected by the only strain carrying all the virulence factors considered. Potential large variability of virulence was evidenced among V329 and all bap-positive Staph. aureus strains considered: the carriage of fnb could enhance the accumulation of biofilm, but the lack of lukD/E and splA, B or E might decrease the invasiveness of strain.

We report the application of a novel optical Raman-based measurement technique for the simultaneous determination of the progress of mixing on the micro- and on the macro-scale. The introduced measurement technique is applicable to mixing systems containing one compound, which potentially can form hydrogen bonds, such as water, alcohols or amines, and does not rely on the addition of traces of indicator compounds. Here we demonstrate its applicability by analyzing the lag of micro-mixing behind macro-mixing when liquid ethanol is injected into a supercritical bulk environment mainly composed of carbon dioxide (CO2). While the degree of mixing on the macro-scale is determined from the ratio of the intensities of characteristic Raman signals of ethanol and CO2, the degree of mixing on the micro-scale is determined from the shape of the OH stretching vibration Raman signal of ethanol, which is a function of the development of hydrogen bonds.