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Modulation of Physical and Chemical Properties of Encapsulated Guests by Macrocyclic Hosts
No full textThroughout my doctoral studies I have focused on how cucurbit[n]urils (CBn), as supramolecular hosts, can be used to modulate the physical and chemical properties of guest molecules. My results are published as several articles in peer reviewed journals.
In gas phase, I have used CBn (n = 6-8) as macrocyclic hosts and bicyclic azoalkanes as guests to investigate inner-phase chemical reactions. The results of my systematic mass spectrometry study reveal a sensitive interplay in which attractive and repulsive van der Waals interactions between the differently sized hosts and guests need to be balanced with a constrictive binding to allow thermally activated chemical reactions to compete with dissociation.
In aqueous solution, I have uncovered a novel mechanism for modulating the fluorescence properties of Förster-cycle-prone dyes with cation-receptor macrocycles and I reveal the high-affinity and selectivity of CBn (n = 7, 8) as hosts for steroid complexation, as well as consequential applications.
In the novel fluorescence activating study, protonated free dyes are prone to undergo a rapid deprotonation in their excited state to result in fluorescence from the unprotonated form (Förster cycle). The deprotonation can be suppressed by complexation, coined as host-retarded excited-dye deprotonation, which allows the fluorescence of the locally excited (protonated) state to be dramatically enhanced.
In the study of steroids (21 tested) with CBn (n = 7, 8), fluorescence displacement titrations and isothermal titration calorimetry (ITC) provided up to nanomolar binding affinities in aqueous solution for these hydrophobic target molecules, exceeding the values of known synthetic receptors. Remarkable binding selectivities, even for homologous steroid pairs, were investigated in detail by NMR, X-ray crystal diffraction, ITC, and quantum-chemical calculations. In addition, a bacterial assay has been designed and demonstrated, based on CB8
Multiple health behaviors, subjective health, quality of life and sleep quality: Theory-based investigations and implications for health promotion and disease prevention
No full textMany lifestyle factors can contribute to the deterioration of health. The rise in non-communicable diseases and high-level of stress can result in being less productive at work, shorter lifespans, and a more significant burden on the healthcare system. Therefore, the primary goal of this thesis is to identify the interrelations among multiple health behaviors, and their associations with subjective health, quality of life, and sleep quality. Little is known about sleep as another lifestyle-related health behavior, thus, the second goal is to include sleep as health behavior. As health and engagement in health behaviors vary with age and subjective perspectives, the third goal of this thesis is to investigate age-group differences on multiple health behaviors, and their associations with subjective health, quality of life and sleep quality.This thesis utilized theory-based and empirical investigations based on quantitative questionnaire data. Results suggest that individuals who were physically active were more likely to perceive their health as better, over a period of up to eight years (N=640). Some initial insights were provided regarding how sleep interrelates with physical activity and healthy diets among older adults (N=126). The results further suggest that these multiple health behaviors are associated with increased subjective health, quality of life, and sleep quality, and show significant age group differences (N=790). The findings based on the Compensatory Carry-Over Action Model reflect (1) that carry-over mechanisms of one health behavior may facilitate other health behavior; (2) the understanding of self-regulation of multiple health behaviors in achieving higher-level goals could enhance health and well-being. Adapting lifestyle management with multiple health behaviors, including sleep, may be informative for practical implications of health promotion. Future study should identify the causal pathway of health behaviors and social cognitive factors
Bildungspolitische Steuerungspotentiale im Feld der Weiterbildung
No full textEducation is one of the most important factors for the cultural, economic, political, and social development of modern societies. Consequently, all areas of education are increasingly moving into the focus of political governance demands of actors on both national and supranational levels. The achievement of such political objectives, however, poses major challenges for the actors. Especially the area of continuing education is characterized by a high degree of heterogeneity on all levels of action. Therefore, continuing education often resists direct interventions of political actors.
The present cumulative thesis presents four studies that examined the political governance potentials in the area of continuing education for actors on the national and the supranational levels. The chances of successful interventions concerning the typical functions of the education system in modern society and the corresponding political objectives were analyzed on different levels of action. It was of special interest, which level of action is most suitable for political governance and what mode of coordinated social action is particularly effective. A multi-level model of continuing education was used as the basis for this research.
The results show that the national framework represents a highly relevant context of continuing education behavior. Furthermore, public spending on education increases the participation of the adult residential population, with low-skilled persons especially benefitting from these expenditures. Public spending on education was used as a proxy for the degree of decommodification of the education system. Regional and local contexts, however, turn out to be less important contexts of continuing education behavior. The strongest effect on the continuing education behavior can be seen for the context of counties and cities.
In addition, these administrative spatial divisions are of particular importance as coordination frameworks of regional continuing education landscapes at the level of the institutional environment of continuing education organizations. Here, the effects of politically initiated education networks on the continuing education behavior of the entire population as well as for educationally disadvantaged subpopulations were examined. The analyses identified a small but significant effect only for low-skilled males.
At the level of action of the further education organizations, it was examined to what extent cooperation between continuing education centers and other institutions, as laid down in the further education laws of most federal states in Germany, are suitable for implementing additional participations and for opening up previously inaccessible participation potentials. The results show that cooperation allows for additional course offerings, which are accompanied by additional participation. Furthermore, cooperation provides a chance for adult education centers to gain new groups of participants in the long term
Shape-based Machine Perception of Man-Made Objects on Underwater Sensor Data
No full textThis thesis focuses on the common case in underwater robotics where the objects that need to be perceived are man-made and known a-priori. The idea is that the information about the shape of the object can efficiently guide object localization, segmentation and classification algorithms to the correct result while mitigating the strong noise and occlusions present on underwater sensor data.
In this thesis different implementations of the general idea of using shape a-priori knowledge are investigated. First an efficient screening algorithm that finds potential target objects on synthetic aperture sonar images. In this thesis a fast integral image based template matching framework is described. New template types and feature types that take the shape of the objects of interest into account and that are tailored to the detection on synthetic aperture sonar images are introduced.
For the segmentation of noisy sensor data a superellipse fitting onto already extracted object contours is investigated. To this end, a novel linearisation of the fitting error equation was proposed. Experiments showed that the linearisation decreased the computation time significantly. A second approach towards segmentation of noisy sensor data was made by reformulating the active contours without edges framework to accommodate a superellipse shape constraint. With the new formulation it was also discovered that the implicitly assumed underlying Gaussian pixel intensity distribution can easily be substituted to a more fitting pixel distribution. This is especially beneficial when the imaging system is not an optical camera but for example a sonar or another challenging noisy imaging system.
The last method proposed in this thesis employs the a-priori known shapes to do a top-down classification verification via a new proposed method to approximately simulate the sonar image. The experiments show that the top-down approach is a valuable tool to identify false positives
Interference and Secrecy Optimization in Wireless Networks
No full textMobile wireless networks are undoubtedly one of the main drivers of industrial development and economic growth in modern societies. This central role explains current trends which indicate unequivocally that future cellular systems must cope with enormous increase in user-capacity coupled with a reduction in energy consumption. However, as of recently, this scalability/efficiency problem has been addressed through infrastructural and topological enhancements to the existing wireless networks. This will create additional spatial domain, which will serve as a means to solve the scalability/efficiency issue. Along with this, challenges in the form of signal interference remains the main adversary of systems engineers. Compounding the problem is the current wireless framework, which predominantly consists of diverse inter-connected devices in highly dense and mobile environment, and thus, intuitively inter- and intra- interferences are guaranteed to prevail. In this thesis, despite traditional concept that identify interference as a deleterious phenomenon, we have investigated two approaches that contemplate interference as a beneficial resource. The first approach exploits the interference at the baseband level, and leads to multiuser precoding which ultimately results in improved quality of service, such as achievable rate, especially for cell-edge users. On the other hand, the second concept exploits interference as means to trick (jam) potential intruders (eavesdroppers). In the continuously evolving wireless environment, there exists broad range of � financial, political and environmental applications that require confidential and secure transmission of information, this prompt devising security measures as a paramount task. In this sequel, physical layer security (PLS) measures have been proposed as alternative to the more complex upper layer encryption and cryptographic protocols
Reducing Plastic Bag Use in Indonesia
No full textHow can plastic bag use in Indonesia be reduced? This dissertation attempts to answer this question applying two approaches:
(1) Utilizing qualitative and quantitative research to investigate crucial factors explaining plastic bag use;
(2) Conducting natural field experiments to identify effective behavioral interventions reducing the use of plastic bags in Indonesia.
The pollution of the oceans by plastic waste is a growing threat to marine life, ecosystems, livelihoods of coastal communities and the health of human beings in general. Indonesia is the world’s second largest source of marine plastic pollution. Regulations and policies have shown to be effective in the reduction of the use of and pollution by plastic bags in a number of countries. But for the Indonesian Government and many other governments the feasibility of implementing and enforcing such measures is limited. Given this situation, there is an urgent need to investigate and find effective alternative approaches to reduce plastic bag use. Such alternative approaches include non-governmental organizations, environmental groups and social enterprises.
This research aims to explain plastic bag use with the help of research methods from cultural anthropology. Qualitative and quantitative methods were applied along with different types of triangulation to examine people’s concepts of nature, the perceived benefits and disadvantages of plastic bag use, and promising local initiatives.
To find effective behavioral interventions for reducing plastic bag use we conducted natural field experiments. These tested normative and economic interventions in combination with ecofriendly reusable shopping bags. Specific interventions ranged from social norms and different societal authorities to indirect monetary incentives and bonus schemes. In this context we also analyzed socio-economic factors and environmental awareness in relation to frequency of plastic bag use
The DNA from a Communications and Information Theoretic Perspective
No full textBeyond enabling the successful development of communication engineering, information theory has far-reaching applications in other disciplines, including molecular biology. Information theory has been effectively applied for analyzing and modeling biological systems and processes. Following the same framework, in this thesis, three related but distinct topics are studied. First, we modeled the transmission of genetic information assuming a codon-based mutation matrix as a communication channel and performed capacity computations. Furthermore, the severity of codon substitution errors was assessed by comparing mutation probabilities with chemical properties of amino acids using a dimension reduction technique. The second topic deals with the analysis of the relationship between the digital and analog information in bacterial genomes. The latter represents the three-dimensional information encoded by the physicochemical properties of the DNA. Here, the analog information is associated with thermodynamic stability. In addition, the spatial genomic sequence organization is studied in relation to selected functional classes of genes. Finally, a novel method of essential gene prediction based on machine-learning is proposed. Information-theoretic measures have been used as features and essentiality predictions were performed in both prokaryotes and eukaryotes. The obtained results show that gene essentiality annotations can be reliably transferred between both closely and distantly related species
Self-Assembled Monolayer-Tuned Growth of ZnO Nanorods for Organic Solar Cells
No full textOrganic solar cells have the potential to meet the rising energy demand. They offer
great prospects due to inexpensive processing techniques. They can be fabricated at low temperatures, which makes them compatible for large scale roll-to-roll printing. Despite high absorption coefficients of organic semiconductors, there is significant absorption loss. ZnO nanorods can scatter incoming light and elongate optical path length, thereby enhancing absorption in semiconductor layer. Secondly, ZnO nanorods can serve as charge collection pathways to electrodes. For light scattering, it is critical to control dimensions and distribution of ZnO nanorods. In this thesis, a method is introduced to achieve controlled growth of ZnO nanorods via electrochemical deposition. Self-assembled monolayer (SAM) of alkanethiol molecule is applied on substrate to define ZnO nucleation sites. A growth model of ZnO on SAM-modified substrate is developed and it is supported by impedance measurements. The dimensions and nucleation density of nanorods are varied by changing quality of SAM and parameters of electrochemical deposition. Angle-resolved transmission measurements are performed to study light scattering properties of ZnO nanorods. Bulk heterojunction organic solar cells are successfully fabricated with ZnO nanorods and semiconductors poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Charge carrier mobility plays a big role in organic semiconductors. MIS-CELIV (metal-insulator-semiconductor charge carrier extraction by linearly increasing voltage) technique is used to get selective mobility of holes and electrons in semiconductor blend of P3HT:PCBM. A simulation method based on 1-D drift-diffusion equation is used to analyze MIS-CELIV measurements. This method includes doping and trapping, which have been ignored in traditional MIS-CELIV analysis. An analytical model is also introduced which allows determination of semiconductor conductivity
Local streams and global tides - Understanding coastal marine governance in Fiji and Solomon Islands
No full textThis PhD thesis contributes to understanding coastal marine governance in Fiji and Solomon Islands. It examines community-based marine resource management (CBMRM) approaches based on customary marine governance systems, while also considering interactions with the national governance frameworks for coastal fisheries in both countries. Based on qualitative research methods and analysis, this study uses a range of conceptual and analytical lenses. A social-ecological system (SES) perspective serves to identify key contextual factors and actors that influence the governance of coral-reef SESs. A gender lens is used to distill women’s and men’s differentiated roles and participation in marine resource use and governance. Furthermore, this study ascertains drivers of local (non-) compliance with and enforcement of CBMRM. Finally, a legal pluralism perspective is taken to scrutinize the interactions across the different governance systems in place, i.e., customary governance systems and the national governance systems for coastal fisheries. Overall, this thesis aims to address the challenge of how to sustainably use and manage marine (coral reef) resources in Fiji and Solomon Islands. It identifies points of leverage to improve coastal marine governance that are relevant both for policy and practice, and which may be useful for the local, national and subnational levels
Plasmid-based recombination events in the yeast Saccharomyces cerevisiae
No full textYeast, in particular Saccharomyces cerevisiae, is a frequently used host for the production of numerous nutritional and pharmaceutical compounds. Cells can be transformed in order to produce recombinant products with the foreign genetic information being placed on hybrid multi-copy plasmids (YEp-type) due to the anticipated gene dosage effect. These plasmids contain sequences of the yeast endogenous 2µm plasmid encompassing its origin of replication. Expression vectors based on the 2μm plasmid are the only vectors in S. cerevisiae which satisfy two major biotechnological requirements: segregational stability and high copy number. Under non-selective conditions, those plasmids show, however, a lower stability compared to the authentic 2µm plasmid.
Stability can be divided into structural and segregational stability. Both were analyzed in detail for a set of isomeric YEp-type plasmids created in this work. Efforts were made to investigate plasmid-based recombination events that on the one hand allow the plasmid to amplify by employing 2µm-encoded proteins and on the other hand affect the stability of the plasmid. The correct structure might be compromised by the innate amplification mechanism of YEp-type plasmids, adapting a similar mechanism as the endogenous 2µm. This work identified multiple structures that likely represent amplification intermediates where YEp–type plasmid and 2µm fusion products were found. This thesis work shows that the architecture of functional elements of a basic multicopy model plasmid has a huge impact on the segregational stability with differences of up to 5.7-fold between the eight isoforms created. The addition of a synthetic gene coding for a yEGFP3 reporter protein to a particularly stable model plasmid in all possible positions and orientations has an influence on both structural and segregational stability. One particularly favorable and one unfavorable isoform were identified