Bøker utgitt av Cuvillier

The main topic of this thesis is the influence of the dielectrophoretic (DEP) force on a thermal convection in a cylindrical annulus under microgravity conditions of parabolic flights. To perform these experiments a specialized experimental setup was designed. The annulus is differentially heated to create a temperature gradient and an ac voltage of up to 10kV is applied. Two different experiment setups were build for different measurement methods. One for Shadowgraph and Synthetic Schlieren methods and the other for PIV measurements. Several complex flow patterns can be identified by combining the resulting images from both visualization mthods. The heat transfer is determined under different experimental conditions. Under the given conditions it is possible to make a correlation between the flow patterns and the level of the convective heat transfer. The experimental data is compared to theoretical data from a linear stability analysis. The patterns predicted by the can also found in the experiments.

Increasing vehicle performance requirements and virtualization of its development process require more understanding of physical background of tire behavior, especially in transient rolling conditions with combined slip. The focus of this research is physical description of transient generation of tire lateral force and aligning torque. Using acceleration measurement on the tire inner liner it was observed that the contact patch shape of the rolling tire changes nonlinearly with slip angle and becomes asymmetric. Optical measurement outside and inside the tire has clarified that carcass lateral bending features both shear and rotation angle of its cross-sections. A physical simulation model was developed, which considers the observed effects. A special iterative computing algorithm was proposed. The model was qualitatively validated using not only tire force and torque responses, but also deformation of the tire carcass. The model-based analysis explained which tire structural parameters are responsible for which criteria of tire performance. Contact patch shape change had a low impact on lateral force and aligning torque. Variation of carcass bending behavior perceptibly influenced aligning torque generation. As an example, the gained understanding was applied for feasibility analysis of a novel method to estimate the utilized friction potential rate of a rolling tire.

Scope of the work is the kinetic investigation of two fourth generation Ziegler-Natta catalysts as well as a supported metallocene catalyst for the polymerization of propylene under industrially relevant conditions and the development of simplified phenomenological kinetic models describing the polymerizations. Therein, the influence of different reaction conditions (temperature, pressure, hydrogen concentration) and, in particular, the effect of prepolymerization on catalyst kinetics as well as on polymer characteristics are studied. The Ziegler-Natta catalysts were investigated under gas-phase conditions in a 5 l horizontal stirred tank reactor operating in semi-batch mode. Both catalysts showed a similar kinetic behavior as well as hydrogen response at the different reaction conditions. Applying a prepolymerization led to an increase in activity at higher reaction temperatures as well as an improved polymer morphology. The impact of prepolymerization is catalyst specific and depends on the catalyst activity reached at main polymerization temperature. The supported metallocene catalyst was studied under bulk conditions in liquid propylene using a special 250 ml reaction calorimeter. A focus was set on procedure development (in-situ and external prepolymerization) with the target of defined prepolymerization conditions and early access to the kinetic profile. Final kinetic measurements were carried out using the developed external prepolymerization procedure. Based on the experimental studies, simplified phenomenological kinetic models are developed for each catalyst type enabling the quantitative description of the polymerization reactions at the different reaction conditions including the effect of prepolymerization. Main hypothesis for the mathematical description of the prepolymerization effect is that particle overheating at the beginning of the polymerization is the major reason for lower activities obtained when no prepolymerization is applied. For particle modeling, a quasi-homogeneous particle model is assumed considering particle growth and particle heat-transfer. As similar kinetic behaviors were observed for both Ziegler-Natta catalysts, the same kinetic model can be used; differences can only be described by the catalyst specific amount of polymerization active component. A similar kinetic model approach is used to describe the bulk polymerization with metallocene catalyst. Differences regarding the different polymerization regime, in particular monomer concentration in the polymer particle, hydrogen concentration in liquid phase, are considered. With the estimated sets of kinetic parameters, average activities and average molecular weights can be calculated as well as activity profiles of the catalysts can be quantitatively described at the different reaction conditions.

Consider manufactured parts, such as screws, car doors, lenses, or mirrors for lasers, for example. All these manufactured parts have to go through quality inspections checking if there are unwanted bumps or scratches that should not be there. There are different methods to measure the manufactured parts. The goal is to describe the measured object exactly by the data. This is one example for a so-called inverse problem.The application that we consider in the first part of this thesis is a data fusion process. The given dataset is a result of a deflectometric measurement process. These processes deal with object measurements of specular objects, such as lenses or mirrors. The aim is to calculate a dataset that describes the measured object exactly. The output data consists of two sets of separately measured types of data which suffer from different accuracy due to different sensitivity to noise. We resolve this issue with a data fusion process by solving a minimization problem which uses the more accurat data as a reference value and by duing so increases the other.Taking the gained insights we are able to develop new theories for image denoising. We formulate certain minimization problems in which use suitable reference values. In image denoising the reference value we want to use is an approximation of the image gradient vectors. Consequently, our approaches calculate such an approximation and use it as a reference value. Hence, our approaches are two-stage methods. Another approach to prevent the staircasing effect is to go to higher orders of differentiation within the regularization term. One approach was proposed in 2010 namely the total generalized variation (TGV) functional. We propose different kinds of combinations of these functionals. In this way we are able to formulate different minimization problems that are in some sense equivalent to the TGV problem. One advantage of some of these problems lies in the easy parameter choice rules that perform equally well as the TGV problem. Additionally, the duality gaps of these new problems are finite instead of infinite as it is usually the case in the primal-dual gap for the TGV problem. Hence, these can be used to create a reasonable stopping criterion for the optimization process. An additional advantage is the decreased runtime of the two-stage methods, since the problem is divided into two smaller problems.

Drug delivery systems can increase the pharmacokinetic and pharmacodynamic properties of various therapeutic agents. These systems can ensure a controlled release, improve the specificity of drugs to the target tissue, and therefore decrease side effects to the healthy surrounding tissue. In this work cell penetrating peptoids, which mimic the structure of peptides but exhibit increased stability, were investigated as organelle- and organ-specific carrier molecules. Several fluorescently labelled peptoid libraries, differing for example in length and side-chain composition, were synthesized and investigated with high-throughput screenings in different cell lines. The focus was on the elucidation of structure-function relationships for cellular uptake, intracellular localization and cytotoxicity. Furthermore, the organ targeting of the peptoids was analysed in in vivo studies by using zebrafish as model organism. In addition, the influence of the fluorescent dye on the localization and uptake of the peptoids was investigated.

This book contains a model-based analysis and optimisation of the Haber-Bosch designs for power-to-ammonia. The work presented helps to answer which Haber-Bosch design is suitable for the flexible operation and production by varying process variables: operational pressure, process feed temperature, process feed composition and feed flow rate. Among several Haber-Bosch design possibilities, two synthesis loops and five three-bed autothermal synthesis reactor systems are considered. The synthesis loops vary in terms of ammonia separation unit allocation, i.e. after and before a synthesis reactor system, and the reactor system configurations differ in inter-stage cooling methods. Besides, the operation and production flexibilities, design variants are also compared in terms of yield. All the Haber-Bosch designs allow operation for a large load range span via multi-variable optimisation and therefore are in principle suitable for power-to-ammonia.

The German Alumni Summer School 2018 on 'Education, science and cooperation between German Alumni for sustainable development and biodiversity conservation in Sub-Saharan Africa' was jointly organized by the Faculty of Geography-Department of Cartography, GIS and Remote Sensing, the Faculty of Biology and Psychology-Department of Conservation Biology, and the Karatina University, Kenya - School of Natural Resources and Environmental Studies. This summer school was funded by the German Academic Exchange Service (DAAD) and targeted to the German Alumni from Sub-Saharan Africa as well as scientist and experts from various discipline.The European Union being confronted with mass migration from Sub-Saharan Africa is currently working on a new political and economic strategy for Africa. Moreover German Government initiated and proposed a new level of equal cooperation between Africa and western countries in areas such as education, trade, business development and energy. The main idea is to limit the effects of climate change and avoid climate refugees, to prevent mass migration and to help create a future for Africa's youth', and underscores the current status and efforts of German development policy towards African countries.Sub-Saharan Africa comprises of 49 states with the highest population growth, and by the end of the 21st century the population is likely to triple. The average economic growth rate for Sub-Saharan Africa countries slowed down from 5.1% in 2010 to 1.4 % in 2016. Africa is still the world's poorest continent and widespread poverty is the primary cause of malnutrition and health problems. Catastrophes like famines and the recent hunger in Horn of Africa are additionally induced through climate change and land grabbing. Corruption, armed conflict, political and ethnic tension, terrorist activities, unstable state structures, national debt, dependence on global commodities markets, and inequitable world trade mechanisms are mainly responsible for this unstable and threatening situation. Biodiversity loss and diminishing of African wildlife due to habitat loss and poaching are as well the serious concern and calls for action.

The aim of this work is to develop and characterize widely tunable high-power diode lasers emitting at 976 nm, targeting non-linear frequency conversion applications. This was realized by a master oscillator power amplifier (MOPA) configuration, where the MO provides wavelength stabilization and tuning, while the PA ensures power amplification to the watt level. Two approaches of developing tunable laser sources were investigated.In the first approach, three types of monolithic multi-arm lasers were developed and characterized: two-arm (Y-branch), four- and six-arm distributed-Bragg reflector ridge waveguide (DBR-RW) lasers. Among the main findings of this work is that the performance of these lasers is strongly influenced by the intersection point between the individual arms and less affected by the bend structure. Thermal wavelength tuning of the developed laser sources is obtained by resistor-based micro-heaters embedded on top of the grating sections, where tuning of up to 7.5 nm can be achieved from each arm.The second approach uses sampled-grating (SG) structures to obtain wide wavelength tuning from a single laser cavity. While InP based SG lasers are well established, a milestone of this work is the first-time demonstration of fully functional GaAs-based SG lasers. Up to 21 nm of discrete wavelength tuning is achieved when operating a single SG heater with a SG mode spacing of about 2.3 nm. By operating both heaters, 23.5 nm of quasi-continuous tuning is obtained with a mode spacing of about 115 pm.Among the constructed MOPA systems is a Y-branch based MOPA system with 9.7 nm wavelength tuning and 5.5 W output power. Another system utilizes an SG laser, providing 23 nm of quasi-continuous wavelength tuning with an output power in the watt range.

Contrary to what we might expect, China has a higher proportion of women in senior executive roles than almost any other country in the world, far outstripping Western countries such as the USA, France or Germany ¿ even though there¿s not a gender quota in sight. What makes these female Chinese top managers different? To find out, BettinaAl-Sadik-Lowinski interviewed 35 Chinese women who she came into contact with through her work as an executive coach in China. The result is a unique research project, the ¿Shanghai Women¿s Career Lab¿, which analyses the mechanisms, attitudes and carefully planned career paths that allowed these women to rise to senior positions at multinational corporations in China. The analysis concludes that successful Chinese women and their careers can serve as role models for women around the world. Women can use the results of the research to make their own career planning more successful. By following these examples, they can build on their own strengths and rise to top management. The Shanghai Women¿s Career Lab also offers strategies for company leaders who want to promote talented women to top management positions.

The proceedings were arranged by ICP Ingenieurgesellschaft Prof. Czurda und Partner mbH with high accuracy. Nevertheless, errors cannot be fully excluded. ICP and the editors are not liable or responsible for the correctness of the information in this book. The authors take responsibility for their content. If a brand or trade name was used, there might be trademark rights valid, even if they were not explicitly stated. The proceedings contain complicated technical terms. ICP do not take any liability for the correctness of the translation. Please check the plausibility of the content you are reading.

Unsere Erkenntnisse von der Evolution der frühen, terrestrisch angepassten Reptilien und Amphibien während einer Zeitspanne von vor 320 bis 270 Millionen Jahren auf dem Superkontinent Pangäa sind nur von einer sehr begrenzten Anzahl von Fossilfundstellen bekannt. Die meisten davon liegen in Nordamerika. Die Fossilfundstätte Bromacker in der unterpermischen Tambach-Formation bei Tambach-Dietharz (Deutschland) hat sich während der letzten 25 Jahre mit 11 neuen Arten zur bedeutendsten und produktivsten Fossillagerstätte für unterpermische, terrestrisch angepasste Wirbeltiere außerhalb der USA entwickelt. Der Bromacker enthält die besterhaltenen, terrestrischen Wirbeltierfossilien aus dem Unteren Perm (etwa vor 290 Millionen Jahren). Die Diversität der Fossilien bedeutet, dass der Bromacker das einzige gut dokumentierte Beispiel eines frühen terrestrischen Ökosystems repräsentiert. Das Buch enthält erstmals einen Überblick der Bedeutung des Bromackers mit zahlreichen Fossilabbildungen.Our understanding of the evolution of the earliest terrestrially adapted reptiles and amphibians during the time span 320 to 270 million years ago on the Pangaea supercontinent is known from only very restricted types of fossil localities, most of which are in North America. The fossil locality Bromacker in the Lower Permian Tambach Formation near Tambach-Dietharz (Germany) has developed during the last 25 years with 11 new species to be the most important and productive fossil locality for Lower Permian, terrestrially adapted vertebrates outside USA. The Bromacker locality produces the best preserved terrestrial vertebrate fossils from the Lower Permian time period (about 290 million years ago). The diversity of the fossils indicates that it represents the only fully documented example of an initial stage in the evolution of the modern terrestrial vertebrate ecosystem. The book contains first overview about the importance of the Bromacker with lot of fossil illustrations.

In dieser Arbeit wird eine schiffsbasierte CO2-Transportkette entwickelt und in Hinblick auf einen möglichst geringen Energiebedarf optimiert. Die einzelnen Komponenten der schiffsbasierten CO2-Transportkette werden in Aspen Plus V8.6 modelliert. Für die Verflüssigung von reinem CO2 werden Werte zwischen 7,3 kWh/t CO2 und 14,6 kWh/t CO2 ermittelt. Bei Anwesenheit von typischen CO2-Begleitstoffen aus Post-Combustion- und Oxyfuel-Abscheideprozessen ist der Energiebedarf höher. Für die Injektion von reinem CO2 wird ein Wert von 3,8 kWh/t CO2 für den elektrischen Energiebedarf und ein Wert von 26,5 kWh/t CO2 für den thermischen Energiebedarf ermittelt (Bohrkopfdruck 120 bar). Anschließend wird die entwickelte Transportkette für drei Beispielszenarien mit verschiedenen Transportkapazitäten, Einspeisecharakteristiken und Begleitstoff-Konzentrationen dimensioniert. Für die betrachteten Transportkapazitäten (1 Mt/a bis 20 Mt/a) erscheint der Einsatz von zwei Schiffen bei einer Transportstrecke von 100 km am sinnvollsten. Bei einer Transportstrecke von 1000 km wird für eine Transportkapazität von 20 Mt/a eine größere Anzahl an Schiffen benötigt.

Die Einschlussqualität von Plasmen in toroidalen Magnetfeldern wird maßgeblich durch den turbulenten Transport senkrecht zum Magnetfeld limitiert. Zonalströmungen sind dabei für die Fusionsforschung von großer Bedeutung, da vermutet wird, dass sie mit der Bildung von Transportbarrieren in Zusammenhang stehen. Diese mesoskopischen Scherströmungen tragen auf Grund ihrer Symmetrie nicht zum turbulenten Transport bei und können durch Verscherung von Wirbeln den radialen Transport unterdrücken. Dabei werden Zonalströmungen in einem Selbstorganisationsprozess von der umgebenden Plasmaturbulenz generiert indem Wirbel durch die Zonalströmung verkippt werden, was die Scherströmung weiter antreibt. Ein Maß für die Verkippung ist der sogenannte Reynolds-Stress, wobei der radiale Gradient des Flussflächenmittels die Antriebskraft der Zonalströmung darstellt. Die Dynamik gleicht dabei einer Räuber-Beute-Beziehung, bei der die Driftwellen die Beute für die Zonalströmungen sind. In Fusionsexperimenten konnte beim spontanen Übergang in ein verbessertes Einschlussregime (H-Mode) ein verstärktes Auftreten von Zonalströmungen mit den charakteristischen Räuber-Beute-Oszillationen nachgewiesen werden. Die Rolle und die genaue Wirkungsweise der Zonalströmungen bei dieser Bifurkation des Plasmaeinschlusses sind jedoch ungeklärt. Ein tieferes Verständnis der Physik der Zonalströmungen, speziell in komplexen Magnetfeldgeometrien, ist daher wünschenswert.Diese Arbeit beschäftigt sich vorwiegend mit der Untersuchung des Antriebsmechanismus von Zonalströmungen, im Speziellen mit der Abhängigkeit von der Magnetfeldgeometrie und dem Einfluss der Kollisionalität. Dazu wurden Messungen am Stellarator-Experiment TJ-K durchgeführt, in Plasmen, die dimensional ähnlich zu Randplasmen von Fusionsexperimenten sind. Die relativ geringen Plasmatemperaturen erlauben den Einsatz von Langmuir-Sonden im gesamten Einschlussgebiet. Mit einem poloidalen Sonden Array, bestehend aus 128 Sonden mit je 32 Sonden auf vier benachbarten Flussflächen, können Dichte- und Potentialfluktuationen mit hoher räumlicher und zeitlicher Auflösung gleichzeitig über den gesamten poloidalen Umfang aufgenommen werden.

The present volume draws on the experience of the Summer School held in August 2018 in Split, where graduate students and experienced scholars met from Germany, Albania, Serbia, Macedonia, and Croatia. All contributions discuss small-scale empirical research on the threatened ideals mentioned in the title as desirable and achievable parts of their daily lives as members of modern universities and civil societies.The contributions can also serve as a general model for open and critical international and intercultural academic discourse in joint teaching, research and publishing.

The ongoing diffusion of digital technologies heralds a major change in the mobility domain as it helps to unearth significant opportunities for the reorganization of socio-technical arrangements that have existed for decades. In this light, both scholars and practitioners have begun to investigate the novel opportunities and challenges confronting the mobilitysector. This cumulative thesis, composed of five individual studies, aspires to provide a comprehensive understanding of the transformational impacts of pervasive digital technologies on business models in the mobility sector. Employing a multi-level perspective, this thesis focuses on three main objectives:(1) shedding light on the nature of digitalization and its impacts on business models in general terms, (2) exploring changes in incumbent mobility firms¿ business models in response to the increased diffusion of digital technologies, and (3) examining the potentials of digital technologies to improve value creation and capture in disruptive mobility business models.The findings underline that digitalization is not only concerned with technical aspects but is rather a socio-technical process of applying digital technologies to broader institutional and social contexts. Due to the diversity of technologies and actors involved, digitalization has evolved into an overarching phenomenon that is beyond the control of single actors and affects changes in firms¿ business models through diverse mechanisms. In addition, this thesis describes how incumbent mobility firms adapt their business models in light of consumers¿ changing preferences and how they source the knowledge necessary to develop innovations that build upon hybrid combinations of physical and digital components.Finally, the thesis elaborates on the capacity of digital technologies to facilitate the rise of disruptive mobility business models by improving their attractiveness for both consumers and providers.The crucial success factor is compatibility with the surrounding digital eco-systems, thus rendering it imperative to co-create and co-capture value with diverse actors, including partners, competitors, and customers. From the findings, this thesis derives valuable implications for both research and practice.

This work focuses on the development of AlGaAs-based diode laser (DL) bars optimized for reaching highest powers and efficiencies at low operation temperatures. Specifically, the quasi continuous wave (QCW) pumping of cryogenically cooled Yb:YAG solid-state lasers is targeted, setting requirements on the wavelength (940 nm), the pulse conditions (pulse length 1.2 ms) and frequency (10 Hz) as well as the lowest DL operating temperature THS ~ 200 K, consistent with economic cooling. High fill-factor bars for QCW operation are to reach high optical performance with optical output powers of P 1.5 kW and power conversion efficiencies of ¿E 60% at these power levels. Understanding the efficiency-limiting factors and the behavior at lower temperatures is necessary to design these devices.Optimizations are performed iteratively in three stages. First, vertical epitaxial designs are studied theoretically, adjusted to the targeted operation temperatures and specific laser parameters are extracted. Secondly, resulting vertical designs are processed into low power single emitters and their electro-optical behavior at low currents is experimentally assessed over a wide range of temperatures. The obtained laser parameters characteristic to the vertical design are then used to extrapolate the laser's performance up to the high targeted currents. Finally, vertical designs promising to reach the targeted values for power and efficiency are processed into high power single emitters and bars which are measured up to the highest currents. Eventually, laser bars are fabricated reaching output powers of 2 kW and efficiencies of 61% at 1.5 kW at an operation temperature of 203 K.

Cette étude scrute et compare la manière dont les locuteurs formulent, contextualisent et varient leurs refus selon qu'ils repoussent des demandes d'aide, invitations et offres faites par leurs amis, leurs patrons, leurs professeurs ou des personnes inconnues dans différents types d'échanges verbaux au Cameroun et en France. S'inscrivant dans le cadre de la pragmatique différentielle des français régionaux, l'analyse met en lumière des stratégies mises en oeuvre par les répondants de ces deux espaces francophones pour concilier deux enjeux socio-pragmatiques du refus dans les interactions quotidiennes, à savoir « dire non » et « préserver les faces et les rapports sociaux ». Se fondant sur des données recueillies auprès d'un groupe d'étudiants camerounais et d'un groupe d'étudiants français, l'étude permet de saisir un pan de la réalité des styles interactionnels camerounais et français.

Electrochemical energy conversion technologies are often seen as key components for the transition to an economy that is powered by renewable energy sources. Knowledge-based design and systematic improvement of electrochemical processes is only possible if the underlying reaction kinetics are well understood.This work is based on the hypothesis that a combination of dynamic electrochemical methods, in-operando techniques, and simulations is a feasible and advantageous way towards the determination of electrochemical reaction kinetics. To demonstrate advantages of such a combined approach, four model systems are studied. Differential electrochemical mass spectrometry (DEMS) data and electrochemical data is used to parameterise physical models of the CO and methanol electrooxidation. The second part covers bioelectrochemical reactions. The first DEMS results on acetate oxidation in electrochemically active biofilms are presented, and storage mechanisms for charge as well as substrate are quantified. Furthermore, conversion pathways and rate constants in bioelectrochemical glycerol oxidation are investigated. In conclusion, it is demonstrated that the identification of electrochemical macrokinetics benefits significantly from the application of dynamic techniques, concentration measurements, physical simulation models.

Am 12.11.2014 wurde die Landeeinheit Philae von der Rosetta Sonde abgesetzt und landete auf dem Kometen 67P/Churyumov-Gerasimenko. Beide Raumfahrzeuge erreichten den Kometen im August 2014 als Teil der ESA Rosetta Mission. Nach dem ersten Aufsetzen versagte das Ankersystem, der Lander prallte ab und kam nach drei weiteren Oberflächenkontakten unter einem Kliff zum Liegen. Aufgrund des dortigen Schattens konnten die Akkus nicht aufladen, und der Funkkontakt brach am 15.11.2014 um 00:36 UTC ab. Rosetta blieb für weitere zwei Jahre im Orbit, um die Entwicklung des Kometen zu untersuchen. Diese Arbeit behandelt den Philae Lander, speziell die Messungen mit dem ROMAP Magnetometer. Während des Abstiegs und nach der Landung waren sowohl das Orbiter Magnetometer RPC-MAG als auch das ROMAP Magnetometer gleichzeitig aktiv und ermöglichten simultane Zweipunkt-Messungen. Diese erlaubten es, die niederfrequenten "Singing-Comet" Plasmawellen im Bereich von 5 mHz bis 50 mHz zu analysieren. Die Messungen wurden darüber hinaus verwendet, um die Dynamik des Landers und die Magnetisierung des Kometen während des Abstiegs und des weiteren Flugs zu bestimmen. Aus der Dynamik konnte eine obere Grenze von 800 Pa für die Druckfestigkeit des Oberflächenmaterials des Kometen abgeleitet werden.

BeschreibungDas Gefrieren von Brotteig ermöglicht eine beträchtliche Steigerung der betrieblichen Flexibilität in der Backbranche, jedoch erfolgt dies auf Kosten der Produktqualität.Die während des Einfrierens, der TK-Lagerung und des Auftauens stattfindenden physikalischen und chemischen Veränderungen sind bisher nur zum Teil verstanden. Das erste Ziel der vorliegenden Arbeit bestand darin, eine Methode zur Untersuchung der Mikrostruktur gefrorenen Brotteigs zu entwickeln. Die Methode nutzt die spezifischen Raman-Spektren der Hauptbestandteile gefrorenen Teigs, um ihre jeweilige räumliche Verteilung in den Proben zu ermitteln und entsprechende Bilder zu generieren. Auf den so gewonnenen Bildern stellte sich Eis als kontinuierliches dreidimensionales Netzwerk dar. Außerdem zeigte sich, dass die Bildung größerer Eisblöcke während des Gefrierens durch die Anwesenheit der anderen Teigbestandteile stark limitiert wird.Weizenmehl hat eine komplexe chemische Zusammensetzung, als Ergebnis zahlreicher genetischer sowie Umwelt- und Prozessfaktoren. Das zweite Ziel der Arbeit bestand darin, unter den in der Wertschöpfungskette üblichen analytischen Methoden diejenigen zu identifizieren, die die besten Aussagen zur Eignung der Mehle für TK-Anwendungen geben. Methoden, die die Funktionalität des Glutens sowie die Wasseraufnahme charakterisieren, zeigten sich diesbezüglich als besonders relevant.

BeschreibungThe recent rise of bio-succinic acid as an industrial platform chemical has brought the rumen bacterium Basfia succiniciproducens, a natural producer of this organic acid, into the focus of research. This work investigated the potential of B. succiniciproducens for the production of carbon-three chemicals from sugars. Beside the optimization of improved genetic tools, the C3 chemicals alanine, ß-alanine and 3-hydroxypropionate (3-HP) were targeted. A new alanine producer, B. succiniciproducens ALA-1, exhibited good performance in the bioprocess. The next step demonstrated the proof-of-concept for ß-alanine synthesis using the heterologous expression of aspartate 1 decarboxylase genes from Corynebacterium glutamicum or Vibrio natriegens. The expression of two additional genes enabled the de novo synthesis of up to 100 mg L-1 3-HP from glucose.

BeschreibungCowpea aphid (Aphis craccivora Koch) is a major pest of cowpea, an important African Indigenous Vegetable (AIV) in tropical Africa. Cowpea leaves are a popular delicacy providing daily balanced dietary requirements for millions of people. Synthetic chemicals are first choice management strategy for this pest despite their associated risks of food safety, environmental pollution, and development of resistance by the pest. Consumers are increasingly demanding less use of pesticides and this had led to search of alternative pest management products. This study has identified an environmentally and user entomopathogenic fungi based biopesticide that can be used in the management of A. craccovora in vegetables. The efficacy of cowpea aphid control has been enhanced through incorporation of the biopesticide into a cowpea-maize intercropping system. Use of this biopesticide makes economic sense and can confer yield benefit to farm

The fungus Ashbya gossypii is an important industrial producer of riboflavin, i.e. vitamin B2. Here, we developed and then used a highly sophisticated set-up of parallel 13C tracer studies with labeling analysis by GC/MS, LC/MS, 1D, and 2D NMR to resolve carbon fluxes and obtain a detailed picture of the underlying metabolism in the overproducing strain A. gossypii B2 during growth and riboflavin production from a complex industrial medium using vegetable oil as carbon source. Glycine was exclusively used as carbon-two - but not carbon-one (C1) - donor of the vitamin's pyrimidine ring due to the proven absence of a functional glycine cleavage system. Yeast extract was the main carbon source during growth, while still contributing 8 % overall carbon to riboflavin. Overall carbon flux from rapeseed oil into riboflavin equaled 80 %. Transmembrane formate flux simulations revealed that the C1-supply displayed a severe bottleneck during the initial riboflavin production, which was overcome in later phases of the cultivation by intrinsic formate accumulation. The transiently limiting C1-pool was successfully replenished by time-resolved feeding of formate or serine. This increased the intracellular precursor availability and resulted in a riboflavin titer increase of 45 %. This study is the first that successfully sheds light on carbon fluxes during the growth and riboflavin production phase by use of 13C tracers and a complementary platform of analytical techniques.

Terahertz (THz) technology bears great potential in spectroscopy, imaging, material science, security screening and high-speed wireless communication. However, the generation of intensive, directional THz radiation has been difficult and the THz frequency range has long been considered the last final frontier of the electromagnetic spectrum. Recent advancement in optoelectronic terahertz generation techniques and high power electronic sources has helped to bridge the THz gap and has opened up a wealth of new applications for THz technology. However, there is still a major technical limitation in developing THz systems for mass markets, mainly due to the cost of THz hardware components including sources and detectors.In this regard, we investigated the use of semiconductor diode lasers as THz detectors as well as excitation sources for photomixers for THz generation. For THz detection, we investigated the interaction of semiconductor lasers with THz radiation. Intense THz radiation from different sources and at various frequencies was injected into the laser diode. The laser diode was operated in Littman configuration to ensure clean single mode operation in the near infrared. The charge carrier system in the semiconductor was expected to interact with the injected THz radiation and introduce nonlinear frequency mixing. This nonlinear mixing was to induce sidebands in the near infrared optical spectra and was to be analyzed with an optical spectrum analyzer. This may lead to the demonstration of a simple, cost effective and compact room temperature THz spectrometer since the distance between the emission line and the sidebands equals the incident THz frequency. Unfortunatly, due to unprecedented challenges the interaction of THz radiation with diode laser experiment was not successful.

In this PhD thesis, the flow stability in a laboratory three-dimensional prismatic spouted bed is investigated both experimentally and in CFD-DEM simulations. Liquid is injected in bottom-spray configuration with the aim of a homogeneous distribution of the coating suspension on the whole particle bed. The range of stable spouting is increased by the installation of two parallel draft plates. Nevertheless, the instable spouting regime is found to be advantageous for obtaining a homogeneous coating as the draft plates prevent the mixing in the depth of the apparatus. In addition to the investigations on laboratory scale, the residence time behavior in a continuous pilot scale spouted bed is characterized using a novel tracer method with magnetizable particles. The back-mixing in the apparatus is reduced by the insertion of separation plates with defined transfer geometries.

La Universidad de Ciencias Aplicadas de Schmalkalden se ha involucrado intensamente en los últimos años con instituciones en España para llevar a cabo numerosos proyectos existosos de colaboración que van más allá de los programas de intercambio con universidades españolas, igualmente exitosos.Desde que la crisis económica y financiera afectó especialmente a los estados del sur de Europa, la Universidad de Ciencias Aplicadas de Schmalkalden comenzó a explorar sus posibilidades en Alemania y especialmente en el mercado laboral de Thuringia junto con estudiantes y graduados españoles.La Universidad de Ciencias Aplicadas de Schmalkalden tiene una red multidimensional de socios en España, que incluye universidades y colegios (públicos y privados), pero también Centros de Formación Profesional, escuelas y empresas, así como instituciones políticas. Como resultado, ya se está llevando a cabo una comunicación de múltiples capas, que reúne a diferentes actores en el sistema educativo español a través de la Universidad de Ciencias Aplicadas de Schmalkalden.Como parte del programa "Diálogo universitario con el sur de Europa" del Servicio Alemán de Intercambio Académico (DAAD), todas las instituciones asociadas españolas en Schmalkalden pudieron reunirse en un congreso para ampliar la cooperación actual en proyectos innovadores, lo cual aumenta la empleabilidad de jóvenes académicos. La Facultad de Ciencias Económicas y Empresariales de la Universidad de Ciencias Aplicadas de Schmalkalden ha decidido hacer más atractivos sus programas de estudio, especialmente para universidades, socios y estudiantes de habla hispana. Estos enfoques se desarrollarán aún más con los socios españoles y se vincularán de forma intensiva en la extensa red de socios empresariales e industriales de la Universidad de Ciencias Aplicadas de Schmalkalden.Como resultado concreto de la conferencia en Schmalkalden, debe observarse una nueva vinculación de los programas de estudio entre las universidades asociadas españolas y la Hochschule Schmalkalden.

The present volume draws on the experience of the Workshop held in Benin City, Nigeria in May 2018, where doctoral students and experienced mentors met to work on their journal articles from a simple abstract or a first draft to a concrete publication proposal. Since research articles are the most important academic texts in academic careers today, young African scholars must practice to choose current topics, to use appropriate methodologies and argumentation structures, to draw tentative conclusions, and to be aware of limitations and further research necessary in their field. Mentors can advise them to apply proper statistical procedures, to edit their texts carefully and to submit them in acceptable format to appropriate journals.The contributions can also serve as a general model for open and critical international and intercultural academic discourse on publishing research articles in international journals.

The miniaturisation of bioreactors to the microliter-scale and the integration of online sensors for monitoring the most important process variables during the cultivations is a promising approach for the screening and optimization of cultivation and biocatalysis processes, enabling information-rich, parallelised and cost-effective experiments under well-controlled environmental conditions. The main advantages of microbioreactors (MBRs) are minimization of space and reagents, their easy manipulation, and their high-throughput screening potential, which make them very interesting tools to develop bioprocesses.This thesis is focused on the development of MBRs and the sensor integration for monitoring optical density (OD), dissolved oxygen (DO), pH and glucose as well as their validation for different biotechnological applications.On the basis of a developed PDMS-based MBR, a borosilicate glass-based microbubble column-biroeactor (gµBC) (working volume of 60 µL, aeration occurs through a nozzle with Ø =26 µm) was designed and manufactured by wet etching and powder blasting technology. The gµBC proved to have good oxygen transfer capacity, reaching kLa values up to 320 1/h and fast mixing times ¿95 down to 5.5 s when working at a gas superficial velocity uG of 2.25·10-3 m/s. The mixing performance was simulated using a simplified CFD model, and the tracer profile yielded a good qualitative prediction that was comparable to the experimental results, presenting a tolerable deviation of the mixing times. The gµBC was validated as a suitable cultivation screening tool with a batch cultivation of Saccharomyces cerevisiae with the real-time online monitoring of OD and DO.Furthermore, a cuvette-based microbubble column-bioreactor (cµBC) made of polystyrene (working volume of 550 µL, aeration occurs through a nozzle with Ø = 100 µm) was developed and manufactured with online sensors for pH, OD, DO and glucose. The cµBC showed homogeneous mixing of the cultivation medium with ¿95 < 1 s, with high kLa up to 775 1/h at uG of 8.4·10 3 m/s. The applicability of the cµBC for aerobic submerged whole-cell cultivation in batch and chemostat mode was demonstrated with the model organisms S. cerevisiae and Staphylococcus carnosus. In addition, the use of the cµBC for oxygen-dependent (cell-free) biocatalysis was successfully demonstrated with the example of the model enzyme glucose oxidase immobilization on supports to convert glucose via gluconolactone and hydrogen peroxide to gluconic acid in a microfluidic bed bioreactor (µFBR).The characterization of the developed and manufactured MBRs in this work as well as the integration of the online sensors for OD, DO, pH and glucose are now the basis for the future development of a consolidated and parallelisable MBR system for bioprocess development.