@phdthesis{Vranic2019,
  author    = {Vranic, Marija},
  title     = {3D Structure of the biomarker hepcidin-25 in its native state},
  doi       = {10.25932/publishup-45929},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459295},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 135},
  year      = {2019},
  abstract  = {Hepcidin-25 (Hep-25) plays a crucial role in the control of iron homeostasis. Since the dysfunction of the hepcidin pathway leads to multiple diseases as a result of iron imbalance, hepcidin represents a potential target for the diagnosis and treatment of disorders of iron metabolism. Despite intense research in the last decade targeted at developing a selective immunoassay for iron disorder diagnosis and treatment and better understanding the ferroportin-hepcidin interaction, questions remain. The key to resolving these underlying questions is acquiring exact knowledge of the 3D structure of native Hep-25. Since it was determined that the N-terminus, which is responsible for the bioactivity of Hep-25, contains a small Cu(II)-binding site known as the ATCUN motif, it was assumed that the Hep-25-Cu(II) complex is the native, bioactive form of the hepcidin. This structure has thus far not been elucidated in detail. Owing to the lack of structural information on metal-bound Hep-25, little is known about its possible biological role in iron metabolism. Therefore, this work is focused on structurally characterizing the metal-bound Hep-25 by NMR spectroscopy and molecular dynamics simulations. For the present work, a protocol was developed to prepare and purify properly folded Hep-25 in high quantities. In order to overcome the low solubility of Hep-25 at neutral pH, we introduced the C-terminal DEDEDE solubility tag. The metal binding was investigated through a series of NMR spectroscopic experiments to identify the most affected amino acids that mediate metal coordination. Based on the obtained NMR data, a structural calculation was performed in order to generate a model structure of the Hep-25-Ni(II) complex. The DEDEDE tag was excluded from the structural calculation due to a lack of NMR restraints. The dynamic nature and fast exchange of some of the amide protons with solvent reduced the overall number of NMR restraints needed for a high-quality structure. The NMR data revealed that the 20 Cterminal Hep-25 amino acids experienced no significant conformational changes, compared to published results, as a result of a pH change from pH 3 to pH 7 and metal binding. A 3D model of the Hep-25-Ni(II) complex was constructed from NMR data recorded for the hexapeptideNi(II) complex and Hep-25-DEDEDE-Ni(II) complex in combination with the fixed conformation of 19 C-terminal amino acids. The NMR data of the Hep-25-DEDEDE-Ni(II) complex indicates that the ATCUN motif moves independently from the rest of the structure. The 3D model structure of the metal-bound Hep-25 allows for future works to elucidate hepcidin's interaction with its receptor ferroportin and should serve as a starting point for the development of antibodies with improved selectivity.},
  language  = {en}
}
@phdthesis{Krentz2019,
  author    = {Krentz, Konrad-Felix},
  title     = {A Denial-of-Sleep-Resilient Medium Access Control Layer for IEEE 802.15.4 Networks},
  doi       = {10.25932/publishup-43930},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439301},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiv, 187},
  year      = {2019},
  abstract  = {With the emergence of the Internet of things (IoT), plenty of battery-powered and energy-harvesting devices are being deployed to fulfill sensing and actuation tasks in a variety of application areas, such as smart homes, precision agriculture, smart cities, and industrial automation. In this context, a critical issue is that of denial-of-sleep attacks. Such attacks temporarily or permanently deprive battery-powered, energy-harvesting, or otherwise energy-constrained devices of entering energy-saving sleep modes, thereby draining their charge. At the very least, a successful denial-of-sleep attack causes a long outage of the victim device. Moreover, to put battery-powered devices back into operation, their batteries have to be replaced. This is tedious and may even be infeasible, e.g., if a battery-powered device is deployed at an inaccessible location. While the research community came up with numerous defenses against denial-of-sleep attacks, most present-day IoT protocols include no denial-of-sleep defenses at all, presumably due to a lack of awareness and unsolved integration problems. After all, despite there are many denial-of-sleep defenses, effective defenses against certain kinds of denial-of-sleep attacks are yet to be found. The overall contribution of this dissertation is to propose a denial-of-sleep-resilient medium access control (MAC) layer for IoT devices that communicate over IEEE 802.15.4 links. Internally, our MAC layer comprises two main components. The first main component is a denial-of-sleep-resilient protocol for establishing session keys among neighboring IEEE 802.15.4 nodes. The established session keys serve the dual purpose of implementing (i) basic wireless security and (ii) complementary denial-of-sleep defenses that belong to the second main component. The second main component is a denial-of-sleep-resilient MAC protocol. Notably, this MAC protocol not only incorporates novel denial-of-sleep defenses, but also state-of-the-art mechanisms for achieving low energy consumption, high throughput, and high delivery ratios. Altogether, our MAC layer resists, or at least greatly mitigates, all denial-of-sleep attacks against it we are aware of. Furthermore, our MAC layer is self-contained and thus can act as a drop-in replacement for IEEE 802.15.4-compliant MAC layers. In fact, we implemented our MAC layer in the Contiki-NG operating system, where it seamlessly integrates into an existing protocol stack.},
  language  = {en}
}
@phdthesis{Thiede2019,
  author    = {Thiede, Tobias},
  title     = {A multiscale analysis of additively manufactured lattice structures},
  doi       = {10.25932/publishup-47041},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-470418},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xi, 97, LIII},
  year      = {2019},
  abstract  = {Additive Manufacturing (AM) in terms of laser powder-bed fusion (L-PBF) offers new prospects regarding the design of parts and enables therefore the production of lattice structures. These lattice structures shall be implemented in various industrial applications (e.g. gas turbines) for reasons of material savings or cooling channels. However, internal defects, residual stress, and structural deviations from the nominal geometry are unavoidable. In this work, the structural integrity of lattice structures manufactured by means of L-PBF was non-destructively investigated on a multiscale approach. A workflow for quantitative 3D powder analysis in terms of particle size, particle shape, particle porosity, inter-particle distance and packing density was established. Synchrotron computed tomography (CT) was used to correlate the packing density with the particle size and particle shape. It was also observed that at least about 50\% of the powder porosity was released during production of the struts. Struts are the component of lattice structures and were investigated by means of laboratory CT. The focus was on the influence of the build angle on part porosity and surface quality. The surface topography analysis was advanced by the quantitative characterisation of re-entrant surface features. This characterisation was compared with conventional surface parameters showing their complementary information, but also the need for AM specific surface parameters. The mechanical behaviour of the lattice structure was investigated with in-situ CT under compression and successive digital volume correlation (DVC). The deformation was found to be knot-dominated, and therefore the lattice folds unit cell layer wise. The residual stress was determined experimentally for the first time in such lattice structures. Neutron diffraction was used for the non-destructive 3D stress investigation. The principal stress directions and values were determined in dependence of the number of measured directions. While a significant uni-axial stress state was found in the strut, a more hydrostatic stress state was found in the knot. In both cases, strut and knot, seven directions were at least needed to find reliable principal stress directions.},
  language  = {en}
}
@phdthesis{Kegelmann2019,
  author    = {Kegelmann, Lukas},
  title     = {Advancing charge selective contacts for efficient monolithic perovskite-silicon tandem solar cells},
  doi       = {10.25932/publishup-42642},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426428},
  school      = {Universit{\"a}t Potsdam},
  pages     = {v, 155},
  year      = {2019},
  abstract  = {Hybrid organic-inorganic perovskites are one of the most promising material classes for photovoltaic energy conversion. In solar cells, the perovskite absorber is sandwiched between n- and p-type contact layers which selectively transport electrons and holes to the cell's cathode and anode, respectively. This thesis aims to advance contact layers in perovskite solar cells and unravel the impact of interface and contact properties on the device performance. Further, the contact materials are applied in monolithic perovskite-silicon heterojunction (SHJ) tandem solar cells, which can overcome the single junction efficiency limits and attract increasing attention. Therefore, all contact layers must be highly transparent to foster light harvesting in the tandem solar cell design. Besides, the SHJ device restricts processing temperatures for the selective contacts to below 200°C. A comparative study of various electron selective contact materials, all processed below 180°C, in n-i-p type perovskite solar cells highlights that selective contacts and their interfaces to the absorber govern the overall device performance. Combining fullerenes and metal-oxides in a TiO2/PC60BM (phenyl-C60-butyric acid methyl ester) double-layer contact allows to merge good charge extraction with minimized interface recombination. The layer sequence thereby achieved high stabilized solar cell performances up to 18.0\% and negligible current-voltage hysteresis, an otherwise pronounced phenomenon in this device design. Double-layer structures are therefore emphasized as a general concept to establish efficient and highly selective contacts. Based on this success, the concept to combine desired properties of different materials is transferred to the p-type contact. Here, a mixture of the small molecule Spiro-OMeTAD [2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluoren] and the doped polymer PEDOT [poly(3,4-ethylenedioxythiophene)] is presented as a novel hole selective contact. PEDOT thereby remarkably suppresses charge recombination at the perovskite surface, allowing an increase of quasi-Fermi level splitting in the absorber. Further, the addition of Spiro-OMeTAD into the PEDOT layer is shown to enhance charge extraction at the interface and allow high efficiencies up to 16.8\%. Finally, the knowledge on contact properties is applied to monolithic perovskite-SHJ tandem solar cells. The main goal is to optimize the top contact stack of doped Spiro-OMeTAD/molybdenum oxide(MoOx)/ITO towards higher transparency by two different routes. First, fine-tuning of the ITO deposition to mitigate chemical reduction of MoOx and increase the transmittance of MoOx/ITO stacks by 25\%. Second, replacing Spiro-OMeTAD with the alternative hole transport materials PEDOT/Spiro-OMeTAD mixtures, CuSCN or PTAA [poly(triaryl amine)]. Experimental results determine layer thickness constrains and validate optical simulations, which subsequently allow to realistically estimate the respective tandem device performances. As a result, PTAA represents the most promising replacement for Spiro-OMeTAD, with a projected increase of the optimum tandem device efficiency for the herein used architecture by 2.9\% relative to 26.5\% absolute. The results also reveal general guidelines for further performance gains of the technology.},
  language  = {en}
}
@phdthesis{Nagel2019,
  author    = {Nagel, Oliver},
  title     = {Amoeboid cells as a transport system for micro-objects},
  doi       = {10.25932/publishup-44219},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442192},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 84},
  year      = {2019},
  abstract  = {Due to advances in science and technology towards smaller and more powerful processing units, the fabrication of micrometer sized machines for different tasks becomes more and more possible. Such micro-robots could revolutionize medical treatment of diseases and shall support to work on other small machines. Nevertheless, scaling down robots and other devices is a challenging task and will probably remain limited in near future. Over the past decade the concept of bio-hybrid systems has proved to be a promising approach in order to advance the further development of micro-robots. Bio-hybrid systems combine biological cells with artificial components, thereby benefiting from the functionality of living biological cells. Cell-driven micro-transport is one of the most prominent applications in the emerging field of these systems. So far, micrometer sized cargo has been successfully transported by means of swimming bacterial cells. The potential of motile adherent cells as transport systems has largely remained unexplored. This thesis concentrates on the social amoeba Dictyostelium discoideum as a potential candidate for an amoeboid bio-hybrid transport system. The use of this model organism comes with several advantages. Due to the unspecific properties of Dictyostelium adhesion, a wide range of different cargo materials can be used for transport. As amoeboid cells exceed bacterial cells in size by one order of magnitude, also the size of an object carried by a single cell can also be much larger for an amoeba. Finally it is possible to guide the cell-driven transport based on the chemotactic behavior of the amoeba. Since cells undergo a developmentally induced chemotactic aggregation, cargo could be assembled in a self-organized manner into a cluster. It is also possible to impose an external chemical gradient to guide the amoeboid transport system to a desired location. To establish Dictyostelium discoideum as a possible candidate for bio-hybrid transport systems, this thesis will first investigate the movement of single cells. Secondly, the interaction of cargo and cells will be studied. Eventually, a conceptional proof will be conducted, that the cheomtactic behavior can be exploited either to transport a cargo self-organized or through an external chemical source.},
  language  = {en}
}
@phdthesis{Grafe2019,
  author    = {Grafe, Marianne Erika},
  title     = {Analysis of supramolecular assemblies of NE81, the first lamin protein in a non-metazoan organism},
  doi       = {10.25932/publishup-44180},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441802},
  school      = {Universit{\"a}t Potsdam},
  pages     = {V, 94},
  year      = {2019},
  abstract  = {Lamine sind Proteine an der inneren Kernh{\"u}lle und bilden zusammen mit verbundenen Proteinen die nukle{\"a}re Lamina. Dieses Netzwerk sorgt f{\"u}r die Stabilit{\"a}t des Zellkerns und unterst{\"u}tzt die Organisation des Zell-Zytoskeletts. Zus{\"a}tzlich sind Lamine und ihre verbundenen Proteine in viele Prozesse wie Genregulation und Zelldifferenzierung involviert. Bis 2012 war der Stand der Forschung, dass nur bei mehrzelligen Organismen eine nukle{\"a}re Lamina zu finden ist. NE81 ist das erste lamin-{\"a}hnliche Protein, das in einem nicht-mehrzelligen Organismus (Dictyostelium discoideum) entdeckt wurde. Es hat viele Eigenschaften und Strukturmerkmale mit Laminen gemeinsam. Dazu z{\"a}hlt der dreiteilige Aufbau des Proteins, eine Phosphorylierungsstelle f{\"u}r ein Zellzyklus-abh{\"a}ngiges Enzym, ein Kernlokalisationssignal, wodurch das Protein in den Kern transportiert wird, sowie eine C-terminale Sequenz zur Verankerung des Proteins in der Kernh{\"u}lle. In dieser Arbeit wurden verschiedene Methoden zur vereinfachten Untersuchung von Laminstrukturen getestet, um zu zeigen, dass sich NE81 wie bereits bekannte Lamin-Proteine verh{\"a}lt und supramolekulare Netzwerke aus Laminfilamenten bildet. Zur Analyse der Struktur supramolekularer Anordnungen wurde das Protein durch Entfernen des Kernlokalisationssignals auf der {\"a}ußeren Kernh{\"u}lle von Dictyostelium gebildet. Die anschließende Untersuchung der Oberfl{\"a}che der Kerne mit einem Rasterelektronenmikroskop zeigte, dass NE81 Strukturen in der Gr{\"o}ße von Laminen bildet, allerdings nicht in regelm{\"a}ßigen filament{\"o}sen Anordnungen. Um die Entstehung der Laminfilamente zu untersuchen, wurde l{\"o}sliches NE81 aus Dictyostelium aufgereinigt und mit verschiedenen mikroskopischen Methoden untersucht. Dabei wurde festgestellt, dass NE81 unter Niedrigsalz-Bedingungen d{\"u}nne, fadenf{\"o}rmige Strukturen und Netzwerke ausbildet, die denen von S{\"a}ugetier-Laminen sehr {\"a}hnlich sind. Die Mutation der Phosphorylierungsstelle von NE81 zu einer imitierenden dauerhaften Phosphorylierung von NE81 in der Zelle, zeigte zun{\"a}chst ein gel{\"o}stes Protein, das {\"u}berraschenderweise unter Blaulichtbestrahlung der Zelle wieder lamin-{\"a}hnliche Anordnungen formte. Die Ergebnisse dieser Arbeit zeigen, dass NE81 echte Laminstrukturen ausbilden kann und hebt Dictyostelium als Nicht-S{\"a}ugetier-Modellorganismus mit einer gut charakterisierten Kernh{\"u}lle, mit allen relevanten, aus tierischen Zellen bekannten Proteinen, hervor.},
  language  = {en}
}
@phdthesis{Nikkhoo2019,
  author    = {Nikkhoo, Mehdi},
  title     = {Analytical and numerical elastic dislocation models of volcano deformation processes},
  doi       = {10.25932/publishup-42972},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429720},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 175},
  year      = {2019},
  abstract  = {The advances in modern geodetic techniques such as the global navigation satellite system (GNSS) and synthetic aperture radar (SAR) provide surface deformation measurements with an unprecedented accuracy and temporal and spatial resolutions even at most remote volcanoes on Earth. Modelling of the high-quality geodetic data is crucial for understanding the underlying physics of volcano deformation processes. Among various approaches, mathematical models are the most effective for establishing a quantitative link between the surface displacements and the shape and strength of deformation sources. Advancing the geodetic data analyses and hence, the knowledge on the Earth's interior processes, demands sophisticated and efficient deformation modelling approaches. Yet the majority of these models rely on simplistic assumptions for deformation source geometries and ignore complexities such as the Earth's surface topography and interactions between multiple sources. This thesis addresses this problem in the context of analytical and numerical volcano deformation modelling. In the first part, new analytical solutions for triangular dislocations (TDs) in uniform infinite and semi-infinite elastic media have been developed. Through a comprehensive investigation, the locations and causes of artefact singularities and numerical instabilities associated with TDs have been determined and these long-standing drawbacks have been addressed thoroughly. This approach has then been extended to rectangular dislocations (RDs) with full rotational degrees of freedom. Using this solution in a configuration of three orthogonal RDs a compound dislocation model (CDM) has been developed. The CDM can represent generalized volumetric and planar deformation sources efficiently. Thus, the CDM is relevant for rapid inversions in early warning systems and can also be used for detailed deformation analyses. In order to account for complex source geometries and realistic topography in the deformation models, in this thesis the boundary element method (BEM) has been applied to the new solutions for TDs. In this scheme, complex surfaces are simulated as a continuous mesh of TDs that may possess any displacement or stress boundary conditions in the BEM calculations. In the second part of this thesis, the developed modelling techniques have been applied to five different real-world deformation scenarios. As the first and second case studies the deformation sources associated with the 2015 Calbuco eruption and 2013-2016 Copahue inflation period have been constrained by using the CDM. The highly anisotropic source geometries in these two cases highlight the importance of using generalized deformation models such as the CDM, for geodetic data inversions. The other three case studies in this thesis involve high-resolution dislocation models and BEM calculations. As the third case, the 2013 pre-explosive inflation of Volc{\´a}n de Colima has been simulated by using two ellipsoidal cavities, which locate zones of pressurization in the volcano's lava dome. The fourth case study, which serves as an example for volcanotectonics interactions, the 3-D kinematics of an active ring-fault at Tend{\"u}rek volcano has been investigated through modelling displacement time series over the 2003-2010 time period. As the fifth example, the deformation sources associated with North Korea's underground nuclear test in September 2017 have been constrained. These examples demonstrate the advancement and increasing level of complexity and the general applicability of the developed dislocation modelling techniques. This thesis establishes a unified framework for rapid and high-resolution dislocation modelling, which in addition to volcano deformations can also be applied to tectonic and humanmade deformations.},
  language  = {en}
}
@phdthesis{Sterzel2019,
  author    = {Sterzel, Till},
  title     = {Analyzing global typologies of socio-ecological vulnerability},
  doi       = {10.25932/publishup-42883},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-428837},
  school      = {Universit{\"a}t Potsdam},
  pages     = {137},
  year      = {2019},
  abstract  = {On a planetary scale human populations need to adapt to both socio-economic and environmental problems amidst rapid global change. This holds true for coupled human-environment (socio-ecological) systems in rural and urban settings alike. Two examples are drylands and urban coasts. Such socio-ecological systems have a global distribution. Therefore, advancing the knowledge base for identifying socio-ecological adaptation needs with local vulnerability assessments alone is infeasible: The systems cover vast areas, while funding, time, and human resources for local assessments are limited. They are lacking in low an middle-income countries (LICs and MICs) in particular. But places in a specific socio-ecological system are not only unique and complex - they also exhibit similarities. A global patchwork of local rural drylands vulnerability assessments of human populations to socio-ecological and environmental problems has already been reduced to a limited number of problem structures, which typically cause vulnerability. However, the question arises whether this is also possible in urban socio-ecological systems. The question also arises whether these typologies provide added value in research beyond global change. Finally, the methodology employed for drylands needs refining and standardizing to increase its uptake in the scientific community. In this dissertation, I set out to fill these three gaps in research. The geographical focus in my dissertation is on LICs and MICs, which generally have lower capacities to adapt, and greater adaptation needs, regarding rapid global change. Using a spatially explicit indicator-based methodology, I combine geospatial and clustering methods to identify typical configurations of key factors in case studies causing vulnerability to human populations in two specific socio-ecological systems. Then I use statistical and analytical methods to interpret and appraise both the typical configurations and the global typologies they constitute. First, I improve the indicator-based methodology and then reanalyze typical global problem structures of socio-ecological drylands vulnerability with seven indicator datasets. The reanalysis confirms the key tenets and produces a more realistic and nuanced typology of eight spatially explicit problem structures, or vulnerability profiles: Two new profiles with typically high natural resource endowment emerge, in which overpopulation has led to medium or high soil erosion. Second, I determine whether the new drylands typology and its socio-ecological vulnerability concept advance a thematically linked scientific debate in human security studies: what drives violent conflict in drylands? The typology is a much better predictor for conflict distribution and incidence in drylands than regression models typically used in peace research. Third, I analyze global problem structures typically causing vulnerability in an urban socio-ecological system - the rapidly urbanizing coastal fringe (RUCF) - with eleven indicator datasets. The RUCF also shows a robust typology, and its seven profiles show huge asymmetries in vulnerability and adaptive capacity. The fastest population increase, lowest income, most ineffective governments, most prevalent poverty, and lowest adaptive capacity are all typically stacked in two profiles in LICs. This shows that beyond local case studies tropical cyclones and/or coastal flooding are neither stalling rapid population growth, nor urban expansion, in the RUCF. I propose entry points for scaling up successful vulnerability reduction strategies in coastal cities within the same vulnerability profile. This dissertation shows that patchworks of local vulnerability assessments can be generalized to structure global socio-ecological vulnerabilities in both rural and urban socio-ecological systems according to typical problems. In terms of climate-related extreme events in the RUCF, conflicting problem structures and means to deal with them are threatening to widen the development gap between LICs and high-income countries unless successful vulnerability reduction measures are comprehensively scaled up. The explanatory power for human security in drylands warrants further applications of the methodology beyond global environmental change research in the future. Thus, analyzing spatially explicit global typologies of socio-ecological vulnerability is a useful complement to local assessments: The typologies provide entry points for where to consider which generic measures to reduce typical problem structures - including the countless places without local assessments. This can save limited time and financial resources for adaptation under rapid global change.},
  language  = {en}
}
@phdthesis{Maerz2019,
  author    = {Maerz, Sven},
  title     = {Analyzing pore systems through comprehensive digital image analysis (DIA)},
  doi       = {10.25932/publishup-44588},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-445880},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 107, xxi},
  year      = {2019},
  abstract  = {Carbonates tend to have complex pore systems which are often composed of distinct assemblages of genetically and geometrically different pore types at various scales (e.g., Melim et al., 2001; Lee et al., 2009; He et al., 2014; Dernaika \& Sinclair, 2017; Zhang et al., 2017). Such carbonate-typical multimodal pore systems are the result of both primary depositional processes and multiple stages of postdepositional modifications, causing small-scale heterogeneities in pore system properties and leading to the co-occurrence of both effective and ineffective pore types. These intrinsic variations in pore type effectiveness are the main reason for the often low correlation between porosity and permeability in carbonate pore systems (e.g., Mazzullo 2004; Ehrenberg \& Nadeau, 2005; Hollis et al., 2010; He et al., 2014; Rashid et al., 2015; Dernaika \& Sinclair, 2017), as it is also true for the marginal lacustrine carbonates studied in this thesis. However, by extracting interconnected and thus effective pore types, and simultaneously excluding isolated and ineffective pores, the understanding and prediction of permeability for given porosity can be highly enhanced (e.g., Melim et al., 2001; Zhang et al., 2017). In this thesis, a step-by-step workflow based on digital image analysis (DIA) is presented and performed on 32 facies-representative samples of marginal lacustrine carbonates from the Middle Miocene N{\"o}rdlinger Ries crater lake (Southern Germany), resulting in 77 mean values of pore type effectiveness which are based on 23,508 individual pore geometry data. By using pore shape factor γ (sensu Anselmetti et al., 1998) as a parameter to quantitatively describe pore shape complexity and therefore pore interconnectivity, the potential contribution (Kcontr.) of each pore type to total permeability (Ktotal) is calculated, and the most effective pore types are then identified. As a result, primary interpeloidal pores and secondary vugs are the most effective pore types in the studied marginal lacustrine succession, mainly due to their generally big size and complex shape, leading to an excellent interconnection between both pore types and consequently to the establishment of a highly effective pore network. Both pore types together compose the pore system of the peloidal grainstone facies. Therefore, this lithofacies type has been identified as the sedimentary facies with highest porosity-permeability properties in this marginal lacustrine succession. By applying the DIA-based method to 23 additional samples from the studied outcrop which all show extensive partial to complete cementation of preexisting pores, the impact of cementation on pore geometry and therefore on porosity and permeability is quantified. This results in a cementation reduction value for each relevant parameter which can then be used to enhance precision of predicting porosity and permeability within the studied succession. Furthermore, the concept of using pore shape complexity as a proxy parameter for pore system effectiveness is tested by applying an independent method (i.e., fluid flow simulation) to the dataset. DIA is then used once again to evaluate the outcome of fluid flow simulation. The results confirm the previous findings that interpeloidal pores and vugs together build up the most effective pore system in the Ries lake carbonates. Finally, the extraction of the interconnected (i.e., effective) pore network leads to an improved correlation between porosity and permeability within the studied carbonates. The step-by-step workflow described in this thesis provides a quantitative petrographic method to identify and extract effective porosity from the pore system, which is crucial for understanding how carbonate pore systems generate permeability. This thesis also demonstrates that pore shape complexity is the most important geometrical parameter controlling pore interconnection and consequently the formation of effective porosity. It further emphasizes that pore shape factor γ (sensu Anselmetti et al. 1998) is a very robust and scale-independent proxy parameter to quantify pore type effectiveness. Additionally, DIA proves to be an ideal tool to directly link porosity and permeability to their mutual origin: the rock fabric and associated pore structure.},
  language  = {de}
}
@phdthesis{Grishina2019,
  author    = {Grishina, Yulia},
  title     = {Assessing the applicability of annotation projection methods for coreference relations},
  doi       = {10.25932/publishup-42537},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-425378},
  school      = {Universit{\"a}t Potsdam},
  pages     = {viii, 198},
  year      = {2019},
  abstract  = {The main goal of this thesis is to explore the feasibility of using cross-lingual annotation projection as a method of alleviating the task of manual coreference annotation. To reach our goal, we build a first trilingual parallel coreference corpus that encompasses multiple genres. For the annotation of the corpus, we develop common coreference annotation guidelines that are applicable to three languages (English, German, Russian) and include a novel domain-independent typology of bridging relations as well as state-of-the-art near-identity categories. Thereafter, we design and perform several annotation projection experiments. In the first experiment, we implement a direct projection method with only one source language. Our results indicate that, already in a knowledge-lean scenario, our projection approach is superior to the most closely related work of Postolache et al. (2006). Since the quality of the resulting annotations is to a high degree dependent on the word alignment, we demonstrate how using limited syntactic information helps to further improve mention extraction on the target side. As a next step, in our second experiment, we show how exploiting two source languages helps to improve the quality of target annotations for both language pairs by concatenating annotations projected from two source languages. Finally, we assess the projection quality in a fully automatic scenario (using automatically produced source annotations), and propose a pilot experiment on manual projection of bridging pairs. For each of the experiments, we carry out an in-depth error analysis, and we conclude that noisy word alignments, translation divergences and morphological and syntactic differences between languages are responsible for projection errors. We systematically compare and evaluate our projection methods, and we investigate the errors both qualitatively and quantitatively in order to identify problematic cases. Finally, we discuss the applicability of our method to coreference annotations and propose several avenues of future research.},
  language  = {en}
}
@phdthesis{Meinig2019,
  author    = {Meinig, Michael},
  title     = {Bedrohungsanalyse f{\"u}r milit{\"a}rische Informationstechnik},
  doi       = {10.25932/publishup-44160},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441608},
  school      = {Universit{\"a}t Potsdam},
  pages     = {X, 137},
  year      = {2019},
  abstract  = {Risiken f{\"u}r Cyberressourcen k{\"o}nnen durch unbeabsichtigte oder absichtliche Bedrohungen entstehen. Dazu geh{\"o}ren Insider-Bedrohungen von unzufriedenen oder nachl{\"a}ssigen Mitarbeitern und Partnern, eskalierende und aufkommende Bedrohungen aus aller Welt, die stetige Weiterentwicklung der Angriffstechnologien und die Entstehung neuer und zerst{\"o}rerischer Angriffe. Informationstechnik spielt mittlerweile in allen Bereichen des Lebens eine entscheidende Rolle, u. a. auch im Bereich des Milit{\"a}rs. Ein ineffektiver Schutz von Cyberressourcen kann hier Sicherheitsvorf{\"a}lle und Cyberattacken erleichtern, welche die kritischen Vorg{\"a}nge st{\"o}ren, zu unangemessenem Zugriff, Offenlegung, {\"A}nderung oder Zerst{\"o}rung sensibler Informationen f{\"u}hren und somit die nationale Sicherheit, das wirtschaftliche Wohlergehen sowie die {\"o}ffentliche Gesundheit und Sicherheit gef{\"a}hrden. Oftmals ist allerdings nicht klar, welche Bedrohungen konkret vorhanden sind und welche der kritischen Systemressourcen besonders gef{\"a}hrdet ist. In dieser Dissertation werden verschiedene Analyseverfahren f{\"u}r Bedrohungen in milit{\"a}rischer Informationstechnik vorgeschlagen und in realen Umgebungen getestet. Dies bezieht sich auf Infrastrukturen, IT-Systeme, Netze und Anwendungen, welche Verschlusssachen (VS)/Staatsgeheimnisse verarbeiten, wie zum Beispiel bei milit{\"a}rischen oder Regierungsorganisationen. Die Besonderheit an diesen Organisationen ist das Konzept der Informationsr{\"a}ume, in denen verschiedene Datenelemente, wie z. B. Papierdokumente und Computerdateien, entsprechend ihrer Sicherheitsempfindlichkeit eingestuft werden, z. B. „STRENG GEHEIM", „GEHEIM", „VS-VERTRAULICH", „VS-NUR-F{\"U}R-DEN-DIENSTGEBRAUCH" oder „OFFEN". Die Besonderheit dieser Arbeit ist der Zugang zu eingestuften Informationen aus verschiedenen Informationsr{\"a}umen und der Prozess der Freigabe dieser. Jede in der Arbeit entstandene Ver{\"o}ffentlichung wurde mit Angeh{\"o}rigen in der Organisation besprochen, gegengelesen und freigegeben, so dass keine eingestuften Informationen an die {\"O}ffentlichkeit gelangen. Die Dissertation beschreibt zun{\"a}chst Bedrohungsklassifikationsschemen und Angreiferstrategien, um daraus ein ganzheitliches, strategiebasiertes Bedrohungsmodell f{\"u}r Organisationen abzuleiten. Im weiteren Verlauf wird die Erstellung und Analyse eines Sicherheitsdatenflussdiagramms definiert, welches genutzt wird, um in eingestuften Informationsr{\"a}umen operationelle Netzknoten zu identifizieren, die aufgrund der Bedrohungen besonders gef{\"a}hrdet sind. Die spezielle, neuartige Darstellung erm{\"o}glicht es, erlaubte und verbotene Informationsfl{\"u}sse innerhalb und zwischen diesen Informationsr{\"a}umen zu verstehen. Aufbauend auf der Bedrohungsanalyse werden im weiteren Verlauf die Nachrichtenfl{\"u}sse der operationellen Netzknoten auf Verst{\"o}ße gegen Sicherheitsrichtlinien analysiert und die Ergebnisse mit Hilfe des Sicherheitsdatenflussdiagramms anonymisiert dargestellt. Durch Anonymisierung der Sicherheitsdatenflussdiagramme ist ein Austausch mit externen Experten zur Diskussion von Sicherheitsproblematiken m{\"o}glich. Der dritte Teil der Arbeit zeigt, wie umfangreiche Protokolldaten der Nachrichtenfl{\"u}sse dahingehend untersucht werden k{\"o}nnen, ob eine Reduzierung der Menge an Daten m{\"o}glich ist. Dazu wird die Theorie der groben Mengen aus der Unsicherheitstheorie genutzt. Dieser Ansatz wird in einer Fallstudie, auch unter Ber{\"u}cksichtigung von m{\"o}glichen auftretenden Anomalien getestet und ermittelt, welche Attribute in Protokolldaten am ehesten redundant sind.},
  language  = {de}
}
@phdthesis{Meyer2019,
  author    = {Meyer, Ljuba},
  title     = {Bildungsort Familie},
  doi       = {10.25932/publishup-44431},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-444319},
  school      = {Universit{\"a}t Potsdam},
  pages     = {V, 438},
  year      = {2019},
  abstract  = {In der Bildungs- und Familienforschung wird die intergenerationale Weitergabe von Bildung innerhalb der Familie haupts{\"a}chlich unter dem Blickwinkel des schulischen Erfolges der nachwachsenden Generation thematisiert. „Wie" aber bildungsbezogene Transferprozesse innerhalb der Familie konkret ablaufen, bleibt jedoch in der deutschen Forschungslandschaft weitestgehend unbearbeitet. An dieser Stelle setzt diese qualitativ angelegte Arbeit an. Ziel dieser Arbeit ist, bildungsbezogene Transferprozesse innerhalb von russischen Dreigenerationenfamilien, die aus der ehemaligen Sowjetunion nach Berlin seit 1989 ausgewandert sind und zwischen der Großeltern-, Elterngeneration und der Enkelgeneration ablaufen, zu untersuchen. Hinter diesen Transferprozessen verbergen sich im Sinne Bourdieus bewusste und unbewusste Bildungsstrategien der interviewten Familienmitglieder. Im Rahmen dieser Arbeit wurden zwei Sp{\"a}taussiedlerfamilien - zu diesen z{\"a}hlen Familie Hoffmann und Familie Popow, sowie zwei russisch-j{\"u}dische Familien - zu diesen z{\"a}hlen Familie Rosenthal und Familie Buchbinder, interviewt. Es wurden mit den einzelnen Mitgliedern der vier untersuchten Dreigenerationenfamilien Gruppendiskussionen sowie mit je einem Vertreter einer Generation leitfadengest{\"u}tzte Einzelinterviews gef{\"u}hrt. Die Erhebungsphase fand in Berlin im Zeitraum von 2010 bis 2012 statt. Das auf diese Weise gewonnene empirische Material wurde mithilfe der dokumentarischen Methode nach Bohnsack ausgewertet. Hierdurch wurde es m{\"o}glich die implizite Selbstverst{\"a}ndlichkeit, mit der sich Bildung in Familien nach Bourdieu habituell vollzieht, einzufangen und rekonstruierbar zu machen. In der Arbeit wurden eine habitustheoretische Interpretation der russischen Dreigenerationenfamilien und die entsprechende Feldanalyse nach Bourdieu vorgenommen. In diesem Zusammenhang wurde der soziale Raum der untersuchten Familien in der Ankunftsgesellschaft bez{\"u}glich ihres Vergleichshorizontes der Herkunftsgesellschaft rekonstruiert. Weiter wurde der Bildungstransfer vor dem jeweiligen Erlebnishintergrund der einzelnen Familien untersucht und diesbez{\"u}glich eine Typisierung vorgenommen. Im Rahmen dieser Untersuchung konnten neue Erkenntnisse zum bisher unerforschten Feld des Bildungstransfers russischer Dreigenerationenfamilien in Berlin gewonnen werden. Ein wesentliches Ergebnis dieser Arbeit ist, dass die Anwendung von Bourdieus Klassentheorie auch auf Gruppen, die in einer sozialistischen Gesellschaft sozialisiert wurden und in eine kapitalistisch orientierte Gesellschaft ausgewandert sind, produktiv sein kann. Ein weiteres zentrales Ergebnis der Studie ist, dass bei zwei der vier untersuchten Familien die Migration den intergenerationalen Bildungstransfer beeinflusste. In diesem Zusammenhang weist Familie Rosenthal durch die Migration einen „gespaltenen" Habitus auf. Dieser ist darauf zur{\"u}ckzuf{\"u}hren, dass diese Familie bei der Planung des Berufes f{\"u}r die Enkelin in Berlin sich am Praktischen und Notwendigen orientierte. W{\"a}hrend die bewusste Bildungsstrategie der Großeltern- und Elterngeneration f{\"u}r die Enkelgeneration im Ankunftsland dem Habitus der Notwendigkeit, den Bourdieu der Arbeiterklasse zuschreibt, zugeordnet werden kann, l{\"a}sst sich hingegen das Freizeitverhalten der Familie Rosenthal dem Habitus der Distinktion zuordnen, der typisch f{\"u}r die herrschende Klasse ist. Ein weiterer Befund dieser Untersuchung ist, dass im Vergleich zur Enkelin Rosenthal bei der Enkelin Popow eine sogenannte Sph{\"a}rendiskrepanz rekonstruiert wurde. So ist die Enkelin Popow in der {\"a}ußeren Sph{\"a}re der Schule auf sich gestellt, da die Großeltern- und Elterngeneration zum deutschen Schulsystem nur {\"u}ber einen geringen Informationsstand verf{\"u}gen. Die Enkelin grenzt sich einerseits von ihrer Familie (innere Sph{\"a}re) und deutschen Schulabbrechern ({\"a}ußere Sph{\"a}re) ab, orientiert sich aber andererseits beim Versuch sozial aufzusteigen an russischsprachigen Peers, die die gymnasiale Oberstufe besuchen (dritte Sph{\"a}re). Bei Enkelin Popow fungiert demzufolge die Peergruppe und nicht die Familie als zentraler Bildungsort. An dieser Stelle sei angemerkt, dass sowohl bei einer russisch-j{\"u}dischen Familie als auch bei einer Sp{\"a}taussiedlerfamilie der intergenerationale Bildungstransfer durch die Migration beeinflusst wurde. W{\"a}hrend Familie Rosenthal in der Herkunftsgesellschaft der Intelligenzija zuzuordnen ist, geh{\"o}rt Familie Popow der Arbeiterschaft an. Daraus folgt, dass der intergenerationale Bildungstransfer der untersuchten Familien sowohl unabh{\"a}ngig vom Sp{\"a}taussiedler- und Kontingentfl{\"u}chtlingsstatus als auch vom herkunftsortspezifischen sozialen Status abl{\"a}uft. Demnach kann geschlussfolgert werden, dass im Rahmen dieser Studie die Migration ein zentraler Faktor f{\"u}r den intergenerationalen Bildungstransfer ist.},
  language  = {de}
}
@phdthesis{Otte2019,
  author    = {Otte, Fabian},
  title     = {C-Arylglykoside und Chalkone},
  doi       = {10.25932/publishup-43430},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434305},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XI, 201},
  year      = {2019},
  abstract  = {Im bis heute andauernden Zeitalter der wissenschaftlichen Medizin, konnte ein breites Spektrum von Wirkstoffen zur Behandlung diverser Krankheiten zusammengetragen werden. Dennoch hat es sich die organische Synthesechemie zur Aufgabe gemacht, dieses Spektrum auf neuen oder bekannten Wegen und aus verschiedenen Gr{\"u}nden zu erweitern. Zum einen ist das Vorkommen bestimmter Verbindungen in der Natur h{\"a}ufig limitiert, sodass synthetische Methoden immer {\"o}fter an Stelle eines weniger nachhaltigen Abbaus treten. Zum anderen kann durch Derivatisierung und Wirkstoffanpassung die physiologische Wirkung oder die Bioverf{\"u}gbarkeit eines Wirkstoffes erh{\"o}ht werden. In dieser Arbeit konnten einige Vertreter der bekannten Wirkstoffklassen C-Arylglykoside und Chalkone durch den Schl{\"u}sselschritt der Palladium-katalysierten MATSUDA-HECK-Reaktion synthetisiert werden. Dazu wurden im Fall der C-Arylglykoside zun{\"a}chst unges{\"a}ttigte Kohlenhydrate (Glykale) {\"u}ber eine Ruthenium-katalysierte Zyklisierungsreaktion dargestellt. Diese wurden im Anschluss mit unterschiedlich substituierten Diazoniumsalzen in der oben erw{\"a}hnten Palladium-katalysierten Kupplungsreaktion zur Reaktion gebracht. Bei der Auswertung der analytischen Daten konnte festgestellt werden, dass stets die trans-Diastereomere gebildet wurden. Im Anschluss konnte gezeigt werden, dass die Doppelbindungen dieser Verbindungen durch Hydrierung, Dihydroxylierung oder Epoxidierung funktionalisiert werden k{\"o}nnen. Auf diesem Wege konnte u. a. eine dem Diabetesmedikament Dapagliflozin {\"a}hnliche Verbindung hergestellt werden. Im zweiten Teil der Arbeit wurden Arylallylchromanone durch die MATSUDA-HECK-Reaktion von verschiedenen 8-Allylchromanonen mit Diazoniumsalzen dargestellt. Dabei konnte beobachtet werden, dass eine MOM-Schutzgruppe in 7-Position der Molek{\"u}le die Darstellung von Produktgemischen unterdr{\"u}ckt und jeweils nur eine der m{\"o}glichen Verbindungen gebildet wird. Die Lage der Doppelbindung konnte mittels 2D-NMR-Untersuchungen lokalisiert werden. In Kooperation mit der theoretischen Chemie sollte durch Berechnungen untersucht werden, wie die beobachteten Verbindungen entstehen. Durch eine auftretende Wechselwirkung innerhalb des Molek{\"u}ls konnte allerdings keine explizite Aussage getroffen werden. Im Anschluss sollten die erhaltenen Verbindungen in einer allylischen Oxidation zu Chalkonen umgesetzt werden. Die Ruthenium-katalysierten Methoden zeigten u. a. keine Eignung. Es konnte allerdings eine metallfreie, Mikrowellen-unterst{\"u}tzte Methode erfolgreich erprobt werden, sodass die Darstellung einiger Vertreter dieser physiologisch aktiven Stoffklasse gelang.},
  language  = {de}
}
@phdthesis{Debsharma2019,
  author    = {Debsharma, Tapas},
  title     = {Cellulose derived polymers},
  doi       = {10.25932/publishup-44131},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441312},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 103},
  year      = {2019},
  abstract  = {Plastics, such as polyethylene, polypropylene, and polyethylene terephthalate are part of our everyday lives in the form of packaging, household goods, electrical insulation, etc. These polymers are non-degradable and create many environmental problems and public health concerns. Additionally, these polymers are produced from finite fossils resources. With the continuous utilization of these limited resources, it is important to look towards renewable sources along with biodegradation of the produced polymers, ideally. Although many bio-based polymers are known, such as polylactic acid, polybutylene succinate adipate or polybutylene succinate, none have yet shown the promise of replacing conventional polymers like polyethylene, polypropylene and polyethylene terephthalate. Cellulose is one of the most abundant renewable resources produced in nature. It can be transformed into various small molecules, such as sugars, furans, and levoglucosenone. The aim of this research is to use the cellulose derived molecules for the synthesis of polymers. Acid-treated cellulose was subjected to thermal pyrolysis to obtain levoglucosenone, which was reduced to levoglucosenol. Levoglucosenol was polymerized, for the first time, by ring-opening metathesis polymerization (ROMP) yielding high molar mass polymers of up to ~150 kg/mol. The poly(levoglucosenol) is thermally stable up to ~220 ℃, amorphous, and is exhibiting a relatively high glass transition temperature of ~100 ℃. The poly(levoglucosenol) can be converted to a transparent film, resembling common plastic, and was found to degrade in a moist acidic environment. This means that poly(levoglucosenol) may find its use as an alternative to conventional plastic, for instance, polystyrene. Levoglucosenol was also converted into levoglucosenyl methyl ether, which was polymerized by cationic ring-opening metathesis polymerization (CROP). Polymers were obtained with molar masses up to ~36 kg/mol. These polymers are thermally stable up to ~220 ℃ and are semi-crystalline thermoplastics, having a glass transition temperature of ~35 ℃ and melting transition of 70-100 ℃. Additionally, the polymers underwent cross-linking, hydrogenation and thiol-ene click chemistry.},
  language  = {en}
}
@phdthesis{Laudan2019,
  author    = {Laudan, Jonas},
  title     = {Changing susceptibility of flood-prone residents in Germany},
  doi       = {10.25932/publishup-43442},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434421},
  school      = {Universit{\"a}t Potsdam},
  pages     = {113},
  year      = {2019},
  abstract  = {Floods are among the most costly natural hazards that affect Europe and Germany, demanding a continuous adaptation of flood risk management. While social and economic development in recent years altered the flood risk patterns mainly with regard to an increase in flood exposure, different flood events are further expected to increase in frequency and severity in certain European regions due to climate change. As a result of recent major flood events in Germany, the German flood risk management shifted to more integrated approaches that include private precaution and preparation to reduce the damage on exposed assets. Yet, detailed insights into the preparedness decisions of flood-prone households remain scarce, especially in connection to mental impacts and individual coping strategies after being affected by different flood types. This thesis aims to gain insights into flash floods as a costly hazard in certain German regions and compares the damage driving factors to the damage driving factors of river floods. Furthermore, psychological impacts as well as the effects on coping and mitigation behaviour of flood-affected households are assessed. In this context, psychological models such as the Protection Motivation Theory (PMT) and methods such as regressions and Bayesian statistics are used to evaluate influencing factors on the mental coping after an event and to identify psychological variables that are connected to intended private flood mitigation. The database consists of surveys that were conducted among affected households after major river floods in 2013 and flash floods in 2016. The main conclusions that can be drawn from this thesis reveal that the damage patterns and damage driving factors of strong flash floods differ significantly from those of river floods due to a rapid flow origination process, higher flow velocities and flow forces. However, the effects on mental coping of people that have been affected by flood events appear to be weakly influenced by different flood types, but yet show a coherence to the event severity, where often thinking of the respective event is pronounced and also connected to a higher mitigation motivation. The mental coping and preparation after floods is further influenced by a good information provision and a social environment, which encourages a positive attitude towards private mitigation. As an overall recommendation, approaches for an integrated flood risk management in Germany should be followed that also take flash floods into account and consider psychological characteristics of affected households to support and promote private flood mitigation. Targeted information campaigns that concern coping options and discuss current flood risks are important to better prepare for future flood hazards in Germany.},
  language  = {en}
}
@phdthesis{Qin2019,
  author    = {Qin, Qing},
  title     = {Chemical functionalization of porous carbon-based materials to enable novel modes for efficient electrochemical N2 fixation},
  doi       = {10.25932/publishup-44339},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443397},
  school      = {Universit{\"a}t Potsdam},
  pages     = {146},
  year      = {2019},
  abstract  = {The central motivation of the thesis was to provide possible solutions and concepts to improve the performance (e.g. activity and selectivity) of electrochemical N2 reduction reaction (NRR). Given that porous carbon-based materials usually exhibit a broad range of structural properties, they could be promising NRR catalysts. Therefore, the advanced design of novel porous carbon-based materials and the investigation of their application in electrocatalytic NRR including the particular reaction mechanisms are the most crucial points to be addressed. In this regard, three main topics were investigated. All of them are related to the functionalization of porous carbon for electrochemical NRR or other electrocatalytic reactions. In chapter 3, a novel C-TixOy/C nanocomposite has been described that has been obtained via simple pyrolysis of MIL-125(Ti). A novel mode for N2 activation is achieved by doping carbon atoms from nearby porous carbon into the anion lattice of TixOy. By comparing the NRR performance of M-Ts and by carrying out DFT calculations, it is found that the existence of (O-)Ti-C bonds in C-doped TixOy can largely improve the ability to activate and reduce N2 as compared to unoccupied OVs in TiO2. The strategy of rationally doping heteroatoms into the anion lattice of transition metal oxides to create active centers may open many new opportunities beyond the use of noble metal-based catalysts also for other reactions that require the activation of small molecules as well. In chapter 4, a novel catalyst construction composed of Au single atoms decorated on the surface of NDPCs was reported. The introduction of Au single atoms leads to active reaction sites, which are stabilized by the N species present in NDPCs. Thus, the interaction within as-prepared AuSAs-NDPCs catalysts enabled promising performance for electrochemical NRR. For the reaction mechanism, Au single sites and N or C species can act as Frustrated Lewis pairs (FLPs) to enhance the electron donation and back-donation process to activate N2 molecules. This work provides new opportunities for catalyst design in order to achieve efficient N2 fixation at ambient conditions by utilizing recycled electric energy. The last topic described in chapter 5 mainly focused on the synthesis of dual heteroatom-doped porous carbon from simple precursors. The introduction of N and B heteroatoms leads to the construction of N-B motives and Frustrated Lewis pairs in a microporous architecture which is also rich in point defects. This can improve the strength of adsorption of different reactants (N2 and HMF) and thus their activation. As a result, BNC-2 exhibits a desirable electrochemical NRR and HMF oxidation performance. Gas adsorption experiments have been used as a simple tool to elucidate the relationship between the structure and catalytic activity. This work provides novel and deep insights into the rational design and the origin of activity in metal-free electrocatalysts and enables a physically viable discussion of the active motives, as well as the search for their further applications. Throughout this thesis, the ubiquitous problems of low selectivity and activity of electrochemical NRR are tackled by designing porous carbon-based catalysts with high efficiency and exploring their catalytic mechanisms. The structure-performance relationships and mechanisms of activation of the relatively inert N2 molecules are revealed by either experimental results or DFT calculations. These fundamental understandings pave way for a future optimal design and targeted promotion of NRR catalysts with porous carbon-based structure, as well as study of new N2 activation modes.},
  language  = {en}
}
@phdthesis{LopezGarcia2019,
  author    = {L{\´o}pez Garc{\´i}a, Patricia},
  title     = {Coiled coils as mechanical building blocks},
  doi       = {10.25932/publishup-42956},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429568},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xi, 130},
  year      = {2019},
  abstract  = {The natural abundance of Coiled Coil (CC) motifs in cytoskeleton and extracellular matrix proteins suggests that CCs play an important role as passive (structural) and active (regulatory) mechanical building blocks. CCs are self-assembled superhelical structures consisting of 2-7 α-helices. Self-assembly is driven by hydrophobic and ionic interactions, while the helix propensity of the individual helices contributes additional stability to the structure. As a direct result of this simple sequence-structure relationship, CCs serve as templates for protein design and sequences with a pre-defined thermodynamic stability have been synthesized de novo. Despite this quickly increasing knowledge and the vast number of possible CC applications, the mechanical function of CCs has been largely overlooked and little is known about how different CC design parameters determine the mechanical stability of CCs. Once available, this knowledge will open up new applications for CCs as nanomechanical building blocks, e.g. in biomaterials and nanobiotechnology. With the goal of shedding light on the sequence-structure-mechanics relationship of CCs, a well-characterized heterodimeric CC was utilized as a model system. The sequence of this model system was systematically modified to investigate how different design parameters affect the CC response when the force is applied to opposing termini in a shear geometry or separated in a zipper-like fashion from the same termini (unzip geometry). The force was applied using an atomic force microscope set-up and dynamic single-molecule force spectroscopy was performed to determine the rupture forces and energy landscape properties of the CC heterodimers under study. Using force as a denaturant, CC chain separation is initiated by helix uncoiling from the force application points. In the shear geometry, this allows uncoiling-assisted sliding parallel to the force vector or dissociation perpendicular to the force vector. Both competing processes involve the opening of stabilizing hydrophobic (and ionic) interactions. Also in the unzip geometry, helix uncoiling precedes the rupture of hydrophobic contacts. In a first series of experiments, the focus was placed on canonical modifications in the hydrophobic core and the helix propensity. Using the shear geometry, it was shown that both a reduced core packing and helix propensity lower the thermodynamic and mechanical stability of the CC; however, with different effects on the energy landscape of the system. A less tightly packed hydrophobic core increases the distance to the transition state, with only a small effect on the barrier height. This originates from a more dynamic and less tightly packed core, which provides more degrees of freedom to respond to the applied force in the direction of the force vector. In contrast, a reduced helix propensity decreases both the distance to the transition state and the barrier height. The helices are 'easier' to unfold and the remaining structure is less thermodynamically stable so that dissociation perpendicular to the force axis can occur at smaller deformations. Having elucidated how canonical sequence modifications influence CC mechanics, the pulling geometry was investigated in the next step. Using one and the same sequence, the force application points were exchanged and two different shear and one unzipping geometry were compared. It was shown that the pulling geometry determines the mechanical stability of the CC. Different rupture forces were observed in the different shear as well as in the unzipping geometries, suggesting that chain separation follows different pathways on the energy landscape. Whereas the difference between CC shearing and unzipping was anticipated and has also been observed for other biological structures, the observed difference for the two shear geometries was less expected. It can be explained with the structural asymmetry of the CC heterodimer. It is proposed that the direction of the α-helices, the different local helix propensities and the position of a polar asparagine in the hydrophobic core are responsible for the observed difference in the chain separation pathways. In combination, these factors are considered to influence the interplay between processes parallel and perpendicular to the force axis. To obtain more detailed insights into the role of helix stability, helical turns were reinforced locally using artificial constraints in the form of covalent and dynamic 'staples'. A covalent staple bridges to adjacent helical turns, thus protecting them against uncoiling. The staple was inserted directly at the point of force application in one helix or in the same terminus of the other helix, which did not experience the force directly. It was shown that preventing helix uncoiling at the point of force application reduces the distance to the transition state while slightly increasing the barrier height. This confirms that helix uncoiling is critically important for CC chain separation. When inserted into the second helix, this stabilizing effect is transferred across the hydrophobic core and protects the force-loaded turns against uncoiling. If both helices were stapled, no additional increase in mechanical stability was observed. When replacing the covalent staple with a dynamic metal-coordination bond, a smaller decrease in the distance to the transition was observed, suggesting that the staple opens up while the CC is under load. Using fluorinated amino acids as another type of non-natural modification, it was investigated how the enhanced hydrophobicity and the altered packing at the interface influences CC mechanics. The fluorinated amino acid was inserted into one central heptad of one or both α-helices. It was shown that this substitution destabilized the CC thermodynamically and mechanically. Specifically, the barrier height was decreased and the distance to the transition state increased. This suggests that a possible stabilizing effect of the increased hydrophobicity is overruled by a disturbed packing, which originates from a bad fit of the fluorinated amino acid into the local environment. This in turn increases the flexibility at the interface, as also observed for the hydrophobic core substitution described above. In combination, this confirms that the arrangement of the hydrophobic side chains is an additional crucial factor determining the mechanical stability of CCs. In conclusion, this work shows that knowledge of the thermodynamic stability alone is not sufficient to predict the mechanical stability of CCs. It is the interplay between helix propensity and hydrophobic core packing that defines the sequence-structure-mechanics relationship. In combination, both parameters determine the relative contribution of processes parallel and perpendicular to the force axis, i.e. helix uncoiling and uncoiling-assisted sliding as well as dissociation. This new mechanistic knowledge provides insight into the mechanical function of CCs in tissues and opens up the road for designing CCs with pre-defined mechanical properties. The library of mechanically characterized CCs developed in this work is a powerful starting point for a wide spectrum of applications, ranging from molecular force sensors to mechanosensitive crosslinks in protein nanostructures and synthetic extracellular matrix mimics.},
  language  = {en}
}
@phdthesis{Goktas2019,
  author    = {Goktas, Melis},
  title     = {Coiled coils as molecular force sensors for the extracellular matrix},
  doi       = {10.25932/publishup-42749},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427493},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiv, 124},
  year      = {2019},
  abstract  = {Kraft spielt eine fundamentale Rolle bei der Regulation von biologischen Prozessen. Zellen messen mechanische Eigenschaften der extrazellul{\"a}ren Matrix und benutzen diese Information zur Regulierung ihrer Funktion. Dazu werden im Zytoskelett Kr{\"a}fte generiert und auf extrazellul{\"a}re Rezeptor-Ligand Wechselwirkungen {\"u}bertragen. Obwohl der grundlegende Einfluss von mechanischen Signalen f{\"u}r das Zellschicksal eindeutig belegt ist, sind die auf molekularer Ebene wirkenden Kr{\"a}fte kaum bekannt. Zur Messung dieser Kr{\"a}fte wurden verschiedene molekulare Kraftsensoren entwickelt, die ein mechanisches Inputsignal aufnehmen und in einen optischen Output (Fluoreszenz) umwandeln. Diese Arbeit etabliert einen neuen Kraftsensor-Baustein, der die mechanischen Eigenschaften der extrazellul{\"a}ren Matrix nachbildet. Dieser Baustein basiert auf nat{\"u}rlichen Matrixproteinen, sogenannten coiled coils (CCs), die α-helikale Strukturen im Zytoskelett und der Matrix formen. Eine Serie an CC-Heterodimeren wurde konzipiert und mittels Einzelmolek{\"u}l-Kraftspektroskopie und Molekulardynamik-Simulationen charakterisiert. Es wurde gezeigt, dass eine anliegende Scherkraft die Entfaltung der helikalen Struktur induziert. Die mechanische Stabilit{\"a}t (Separation der CC Helices) wird von der CC L{\"a}nge und der Zuggeschwindigkeit bestimmt. Im Folgenden wurden 2 CCs unterschiedlicher L{\"a}nge als Kraftsensoren verwendet, um die Adh{\"a}sionskr{\"a}fte von Fibroblasten und Endothelzellen zu untersuchen. Diese Kraftsensoren deuten an, dass diese Zelltypen unterschiedlich starke Kr{\"a}ften generieren und mittels Integrin-Rezeptoren auf einen extrazellul{\"a}ren Liganden (RGD-Peptid) {\"u}bertragen. Dieses neue CC-basierte Sensordesign ist ein leistungsstarkes Werkzeug zur Betrachtung zellul{\"a}rer Kraftwahrnehmungsprozesse auf molekularer Ebene, das neue Erkenntnisse {\"u}ber die involvierten Mechanismen und Kr{\"a}fte an der Zell-Matrix-Schnittstelle erm{\"o}glicht. Dar{\"u}ber hinaus wird dieses Sensordesign auch Anwendung bei der Entwicklung mechanisch kontrollierter Biomaterialien finden. Dazu k{\"o}nnen mechanisch charakterisierte, und mit einem Fluoreszenzreporter versehene, CCs in Hydrogele eingef{\"u}gt werden. Dies erlaubt die Untersuchung der Zusammenh{\"a}nge zwischen molekularer und makroskopischer Mechanik und er{\"o}ffnet neue M{\"o}glichkeiten zur Diskriminierung von lokalen und globalen Faktoren, die die zellul{\"a}re Antwort auf mechanische Signale bestimmen.},
  language  = {en}
}
@phdthesis{Schneider2019,
  author    = {Schneider, Jan Niklas},
  title     = {Computational approaches for emotion research},
  doi       = {10.25932/publishup-45927},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459275},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xv, 145},
  year      = {2019},
  abstract  = {Emotionen sind ein zentrales Element menschlichen Erlebens und spielen eine wichtige Rolle bei der Entscheidungsfindung. Diese Dissertation identifiziert drei methodische Probleme der aktuellen Emotionsforschung und zeigt auf, wie diese mittels computergest{\"u}tzter Methoden gel{\"o}st werden k{\"o}nnen. Dieser Ansatz wird in drei Forschungsprojekten demonstriert, die die Entwicklung solcher Methoden sowie deren Anwendung auf konkrete Forschungsfragen beschreiben. Das erste Projekt beschreibt ein Paradigma welches es erm{\"o}glicht, die subjektive und objektive Schwierigkeit der Emotionswahrnehmung zu messen. Dar{\"u}ber hinaus erm{\"o}glicht es die Verwendung einer beliebigen Anzahl von Emotionskategorien im Vergleich zu den {\"u}blichen sechs Kategorien der Basisemotionen. Die Ergebnisse deuten auf eine Zunahme der Schwierigkeiten bei der Wahrnehmung von Emotionen mit zunehmendem Alter der Darsteller hin und liefern Hinweise darauf, dass junge Erwachsene, {\"a}ltere Menschen und M{\"a}nner ihre Schwierigkeit bei der Wahrnehmung von Emotionen untersch{\"a}tzen. Weitere Analysen zeigten eine geringe Relevanz personenbezogener Variablen und deuteten darauf hin, dass die Schwierigkeit der Emotionswahrnehmung vornehmlich durch die Auspr{\"a}gung der Wertigkeit des Ausdrucks bestimmt wird. Das zweite Projekt zeigt am Beispiel von Arousal, einem etablierten, aber vagen Konstrukt der Emotionsforschung, wie Face-Tracking-Daten dazu genutzt werden k{\"o}nnen solche Konstrukte zu sch{\"a}rfen. Es beschreibt, wie aus Face-Tracking-Daten Maße f{\"u}r die Entfernung, Geschwindigkeit und Beschleunigung von Gesichtsausdr{\"u}cken berechnet werden k{\"o}nnen. Das Projekt untersuchte wie diesen Maße mit der Arousal-Wahrnehmung in Menschen mit und ohne Autismus zusammenh{\"a}ngen. Der Abstand zum Neutralgesicht war pr{\"a}diktiv f{\"u}r die Arousal-Bewertungen in beiden Gruppen. Die Ergebnisse deuten auf eine qualitativ {\"a}hnliche Wahrnehmung von Arousal f{\"u}r Menschen mit und ohne Autismus hin. Im dritten Projekt stellen wir die Partial-Least-Squares-Analyse als allgemeine Methode vor, um eine optimale Repr{\"a}sentation zur Verkn{\"u}pfung zweier hochdimensionale Datens{\"a}tze zu finden. Das Projekt demonstriert die Anwendbarkeit dieser Methode in der Emotionsforschung anhand der Frage nach Unterschieden in der Emotionswahrnehmung zwischen M{\"a}nnern und Frauen. Wir konnten zeigen, dass die emotionale Wahrnehmung von Frauen systematisch mehr Varianz der Gesichtsausdr{\"u}cke erfasst und dass signifikante Unterschiede in der Art und Weise bestehen, wie Frauen und M{\"a}nner einige Gesichtsausdr{\"u}cke wahrnehmen. Diese konnten wir als dynamische Gesichtsausdr{\"u}cke visualisieren. Um die Anwendung der entwickelten Methode f{\"u}r die Forschungsgemeinschaft zu erleichtern, wurde ein Software-Paket f{\"u}r die Statistikumgebung R geschrieben. Zudem wurde eine Website entwickelt (thisemotiondoesnotexist.com), die es Besuchern erlaubt, ein Partial-Least-Squares-Modell von Emotionsbewertungen und Face-Tracking-Daten interaktiv zu erkunden, um die entwickelte Methode zu verbreiten und ihren Nutzen f{\"u}r die Emotionsforschung zu illustrieren.},
  language  = {en}
}
@phdthesis{Codeco2019,
  author    = {Codeco, Marta Sofia Ferreira},
  title     = {Constraining the hydrology at Minas da Panasqueira W-Sn-Cu deposit, Portugal},
  doi       = {10.25932/publishup-42975},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429752},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxviii, 232},
  year      = {2019},
  abstract  = {This dissertation combines field and geochemical observations and analyses with numerical modeling to understand the formation of vein-hosted Sn-W ore in the Panasqueira deposit of Portugal, which is among the ten largest worldwide. The deposit is located above a granite body that is altered by magmatic-hydrothermal fluids in its upper part (greisen). These fluids are thought to be the source of metals, but that was still under debate. The goal of this study is to determine the composition and temperature of hydrothermal fluids at Panasqueira, and with that information to construct a numerical model of the hydrothermal system. The focus is on analysis of the minerals tourmaline and white mica, which formed during mineralization and are widespread throughout the deposit. Tourmaline occurs mainly in alteration zones around mineralized veins and is less abundant in the vein margins. White mica is more widespread. It is abundant in vein margins as well as alteration zones, and also occurs in the granite greisen. The laboratory work involved in-situ microanalysis of major- and trace elements in tourmaline and white mica, and boron-isotope analysis in both minerals by secondary ion mass spectrometry (SIMS). The boron-isotope composition of tourmaline and white mica suggests a magmatic source. Comparison of hydrothermally-altered and unaltered rocks from drill cores shows that the ore metals (W, Sn, Cu, and Zn) and As, F, Li, Rb, and Cs were introduced during the alteration. Most of these elements are also enriched in tourmaline and mica, which confirms their potential value as exploration guides to Sn-W ores elsewhere. The thermal evolution of the hydrothermal system was estimated by B-isotope exchange thermometry and the Ti-in-quartz method. Both methods yielded similar temperatures for the early hydrothermal phase: 430° to 460°C for B-isotopes and 503° ± 24°C for Ti-in-quartz. Mineral pairs from a late fault zone yield significantly lower median temperatures of 250°C. The combined results of thermometry with variations in chemical and B-isotope composition of tourmaline and mica suggest that a similar magmatic-hydrothermal fluid was active at all stages of mineralization. Mineralization in the late stage shows the same B-isotope composition as in the main stage despite a ca. 250°C cooling, which supports a multiple injection model of magmatic-hydrothermal fluids. Two-dimensional numerical simulations of convection in a multiphase NaCl hydrothermal system were conducted: (a) in order to test a new approach (lower dimensional elements) for flow through fractures and faults and (b) in order to identify conditions for horizontal fluid flow as observed in the flat-lying veins at Panasqueira. The results show that fluid flow over an intrusion (heat and fluid source) develops a horizontal component if there is sufficient fracture connectivity. Late, steep fault zones have been identified in the deposit area, which locally contain low-temperature Zn-Pb mineralization. The model results confirm that the presence of subvertical faults with enhanced permeability play a crucial role in the ascent of magmatic fluids to the surface and the recharge of meteoric waters. Finally, our model results suggest that recharge of meteoric fluids and mixing processes may be important at later stages, while flow of magmatic fluids dominate the early stages of the hydrothermal fluid circulation.},
  language  = {en}
}