@phdthesis{Robalo2018,
  author    = {Robalo, Jo{\~a}o Ramiro Alavedra Mendes},
  title     = {Investigating the role of fluorinated amino acids on protein structure and function using simulation},
  school      = {Universit{\"a}t Potsdam},
  pages     = {84},
  year      = {2018},
  language  = {en}
}
@phdthesis{Swart2017,
  author    = {Swart, Corn{\´e}},
  title     = {Managing protein activity in A. thaliana},
  school      = {Universit{\"a}t Potsdam},
  pages     = {160},
  year      = {2017},
  language  = {en}
}
@phdthesis{Yishai2019,
  author    = {Yishai, Oren},
  title     = {Engineering the reductive glycine pathway in Escherichia coli},
  school      = {Universit{\"a}t Potsdam},
  pages     = {86},
  year      = {2019},
  language  = {en}
}
@phdthesis{RuizRodriguez2019,
  author    = {Ruiz Rodriguez, Janete Lorena},
  title     = {Osmotic pressure effects on collagen mimetic peptides},
  school      = {Universit{\"a}t Potsdam},
  pages     = {139},
  year      = {2019},
  abstract  = {Collagen is the most abundant protein in mammals. In many tissues, collagen molecules assemble to form a hierarchical structure. In the smallest supramolecular unit, named fibril, each molecule is displaced in the axial direction with respect to its neighbors. This staggering creates a periodic gap and overlap regions, where the gap regions exhibit 20\% less density. These fibril-forming collagens play an essential role in the strength of connective tissues. Despite much effort, directed at understanding collagen function and regulation, the influence of the chemical environment on the local structural and mechanical properties remains poorly understood. Recent studies, aimed at elucidating the effect of osmotic pressure, showed that collagen contracts upon water removal. This observation highlights the importance of water for the stabilization and mechanics of the collagen molecule. Using collagen mimetic peptides (CMPs), which fold into triple helical structures reminiscent of natural collagen, the primary goal of this work was to investigate the effect of the osmotic pressure on specific collagen-mimetic sequences. CMPs were used as the model system as they provide sequence control, which is essential for discriminating local from global structural changes and for relating the observed effects to existing knowledge about the full-length collagen molecule. Of specific interest was the structure of individual collagen triple helices as well as their organization into self-assembled higher order structures. These key structural features were monitored with infrared spectroscopy (IR) and synchrotron X-ray scattering, while varying the osmotic pressure. For controlling the osmotic pressure, CMP powder samples were incubated in air of defined relative humidity, ranging from dry conditions to highly "humid". In addition, to obtain more biologically relevant conditions, the CMPs were measured in ultrapure water and in solutions containing small molecule osmolytes. Using the sequences (Pro-Pro-Gly)10, (Pro-Hyp-Gly)10 and (Hyp-Hyp-Gly)10, it was shown that CMPs with different degrees of proline hydroxylation (Hyp = hydroxyproline) exhibit a sequence-specific response to osmotic pressure. IR spectroscopy revealed that osmotic pressure changes affect the strength of the triple helix stabilizing, interchain hydrogen bond and that the extent of this change depends on the degree of hydroxylation. X-ray scattering experiments further showed that changes in osmotic pressure affect both the molecular length as well as the higher order organization of CMPs. Starting from a pseudo-hexagonal packing in the dry state, all three CMPs showed isotropic swelling when increasing the water content to approximately 1.2 water molecules per amino acid, again to different extents depending on the degree of hydroxylation. When increasing the water content further, this pseudo-hexagonal arrangement breaks down. In the fully hydrated state, each CMP is characterized by its own specific and more complex packing geometry. While these changes in the lateral packing arrangement suggest swelling upon hydration, an overall decrease of the molecular length (i.e. contraction) was observed in the axial direction. Also for this structural feature, a strong dependency on the specific amino acid sequence was found. Interestingly, the observed contraction is the opposite of what has been reported for natural collagen. As (Pro-Pro-Gly)n, (Pro-Hyp-Gly)n and (Hyp-Hyp-Gly)n repeat units are found in collagen with a relatively high abundance, this suggests that other collagen sequence fragments need to respond to hydration in the opposite way to obtain a net elongation of the full-length collagen molecule. To test this hypothesis, sequences predicted to be sensitive to osmotic pressure were considered. One such sequence, consisting of two repeat units (Ala-Arg-Gly-Ser-Asp-Gly), was inserted as a guest into a (Pro-Pro-Gly) host. When compared to the canonical CMP sequences investigated earlier, the lateral helix packing follows a similar trend with increasing hydration; however, the host-guest CMP axially elongates with increasing water content. This behavior is more similar to what has been found for natural collagen and suggests that different sequences do determine the molecular length of collagen sequences differently. Interestingly, the canonical sequences are more abundant in the overlap region while the guest sequence is found in the gap region. This allows to speculate that sequences in the gap and overlap regions possess a specifically fine-tuned local response to osmotic pressure changes. Clearly, more experiments with additional sequences are needed to confirm this. In conclusion, the results obtained in this work indicate a highly sequence specific interaction between collagen and water. Osmotic pressure-induced conformational changes mostly originate from local geometries and bonding patterns and affect both the structure of individual triple helices as well as higher order assemblies. One key remaining question is how these conformational changes affect the local mechanical properties of the collagen molecule. As a first step, the stiffness (persistence length) of full-length collagen was determined using atomic force microscopy. In the future, experimental strategies need to be developed that allow for investigating the mechanical properties of specific collagen sequences, e.g. performing single-molecule force spectroscopy of CMPs.},
  language  = {en}
}
@phdthesis{Zeppenfeld2021,
  author    = {Zeppenfeld, Stefan},
  title     = {Vom Gast zum Gastwirt?},
  series = {Geschichte der Gegenwart},
  journal   = {Geschichte der Gegenwart},
  number    = {26},
  publisher = {Wallstein-Verlag},
  address   = {G{\"o}ttingen},
  isbn      = {978-3-8353-5022-9},
  pages     = {429},
  year      = {2021},
  abstract  = {Die Arbeitsmigration z{\"a}hlt zu den pr{\"a}genden gesellschaftlichen Wandlungsprozessen der deutschen Nachkriegsgeschichte. 14 Millionen »Gastarbeiter« kamen zwischen 1955 und 1973 in die Bundesrepublik, etwa 3 Millionen von ihnen kehrten nicht in ihre Heimatl{\"a}nder zur{\"u}ck. Vor allem T{\"u}rkeist{\"a}mmige blieben nach dem Anwerbestopp h{\"a}ufiger in Deutschland als die Arbeitskr{\"a}fte aus anderen L{\"a}ndern. Wie keine andere Stadt steht Berlin bis heute f{\"u}r die Einwanderung aus der T{\"u}rkei. Stefan Zeppenfeld untersucht den Wandel der t{\"u}rkischen Arbeitswelten von ihren Anf{\"a}ngen in den 1960er Jahren bis zur Wiedervereinigung. Ausgehend von der »Gastarbeit« im industriellen Großbetrieb sp{\"u}rt er in seiner Studie am Beispiel West-Berlins dem {\"U}bergang in andere Branchen nach. Er zeigt, wie der {\"o}ffentliche Dienst auch f{\"u}r Migrantinnen und Migranten attraktive Aufstiegsm{\"o}glichkeiten er{\"o}ffnete, zeichnet den schwierigen Weg in die gewerbliche Selbstst{\"a}ndigkeit nach und legt illegale Besch{\"a}ftigungsformen als alternative Verdienstm{\"o}glichkeit offen. Damit bettet der Autor die Geschichte der t{\"u}rkischen Arbeitsmigration in die deutsche Zeitgeschichte ein.},
  language  = {de}
}
@phdthesis{Friese2016,
  author    = {Friese, Viviane A.},
  title     = {Solvato-, vapo, mechanochromic and luminescent behavior of Rhodium, Platinum and Gold complexes and their coordination polymers},
  school      = {Universit{\"a}t Potsdam},
  pages     = {100 S.},
  year      = {2016},
  language  = {en}
}
@phdthesis{Rinne2024,
  author    = {Rinne, Theresa Charlotte},
  title     = {The effects of nutrients on bone stem cell function and regeneration},
  school      = {Universit{\"a}t Potsdam},
  pages     = {V, 134},
  year      = {2024},
  abstract  = {Aging is associated with bone loss, which can lead to osteoporosis and high fracture risk. This coincides with the enhanced formation of bone marrow adipose tissue (BMAT), suggesting a negative effect of bone marrow adipocytes on skeletal health. Increased BMAT formation is also observed in pathologies such as obesity, type 2 diabetes and osteoporosis. However, a subset of bone marrow adipocytes forming the constitutive BMAT (cBMAT), arise early in life in the distal skeleton, contain high levels of unsaturated fatty acids and are thought to provide a physiological function. Regulated BMAT (rBMAT) forms during aging and obesity in proximal regions of the bone and contain a large proportion of saturated fatty acids. Paradoxically, BMAT accumulation is also enhanced during caloric restriction (CR), a life-span extending dietary intervention. This indicates, that different types of BMAT can form in response to opposing nutritional stimuli with potentially different functions. To this end, two types of nutritional interventions, CR and high fat diet (HFD), that are both described to induce BMAT accumulation were carried out. CR markedly increased BMAT formation in the proximal tibia and led to a higher proportion of unsaturated fatty acids, making it similar to the physiological cBMAT. Additionally, proximal and diaphyseal tibia regions displayed higher adiponectin expression. In aged mice, CR was associated with an improved trabecular bone structure. Taken together, these findings demonstrate, that the type of BMAT that forms during CR might provide beneficial effects for local bone stem/progenitor cells and metabolic health. The HFD intervention performed in this thesis showed no effect on BMAT accumulation and bone microstructure. RNA Seq analysis revealed alterations in the composition of the collagen-containing extracellular matrix (ECM). In order to investigate the effects of glucose homeostasis on osteogenesis, differentiation capacity of immortalized multipotent mesenchymal stromal cells (MSCs) and osteochondrogenic progenitor cells (OPCs) was analyzed. Insulin improved differentiation in both cell types, however, combination of with a high glucose concentration led to an impaired mineralization of the ECM. In the MSCs, this was accompanied by the formation of adipocytes, indicating negative effects of the adipocytes formed during hyperglycemic conditions on mineralization processes. However, the altered mineralization pattern and structure of the ECM was also observed in OPCs, which did not form any adipocytes, suggesting further negative effects of a hyperglycemic environment on osteogenic differentiation. In summary, the work provided in this thesis demonstrated that differentiation commitment of bone-resident stem cells can be altered through nutrient availability, specifically glucose. Surprisingly, both high nutrient supply, e.g. the hyperglycemic cell culture conditions, and low nutrient supply, e.g. CR, can induce adipogenic differentiation. However, while CR-induced adipocyte formation was associated with improved trabecular bone structure, adipocyte formation in a hyperglycemic cell-culture environment hampered mineralization. This thesis provides further evidence for the existence of different types of BMAT with specific functions.},
  language  = {en}
}
@phdthesis{CruzLemus2020,
  author    = {Cruz Lemus, Saul Daniel},
  title     = {Enhancing Efficiency of Inverted Perovskite Solar Cells},
  school      = {Universit{\"a}t Potsdam},
  pages     = {117},
  year      = {2020},
  abstract  = {Carbon nitride and poly(ionic liquid)s (PILs) have been successfully applied in various fields of materials science owing to their outstanding properties. This thesis aims at the successful application of these polymers as innovative materials in the interfaces of hybrid organic-inorganic perovskite solar cells. A critical problem in harnessing the full thermodynamic potential of halide perovskites in solar cells is the design and modification of interfaces to reduce carrier recombination. Therefore, the interface must be properly studied and improved. This work investigated the effect of applying carbon nitride and PILs on a perovskite surface on the device performance. The facile synthetic method for modifying carbon nitride with vinyl thiazole and barbituric acid (CMB-vTA) yields 2.3 nm layers when solution processing is performed using isopropanol. The nanosheets were applied as a metal-free electron transport layer in inverted perovskite solar cells. The application of carbon nitride layers (CMB-vTA) resulted in negligible current-voltage hysteresis with a high open circuit voltage (Voc) of 1.1 V and a short-circuit current (Jsc) of 20.28 mA cm-2, which afforded efficiencies of up to 17\%. Thus, the successful implementation of a carbon nitride-based structure enabled good charge extraction with minimized interface recombination between the perovskite and PCBM. Similarly, PILs represent a new strategy of interfacial modification using an ionic polymer in an n-i-p perovskite architecture.. The application of PILs as an interfacial modifier resulted in solar cell devices with an extraordinarily high efficiency of 21.8\% and a Voc of 1.17 V. The implementation reduced non-radiative recombination at the perovskite surface through defect passivation. Finally, our work proposes a novel method to efficiently suppress non-radiative charge recombination using the unexplored properties of carbon nitride and PILs in the solar cell field. Additionally, the method for interfacial modification has general applicability because of the simplicity of the post-treatment approach, and therefore has potential applicability in other solar cells. Thus, this work opens the door to a new class of materials to be implemented.},
  language  = {en}
}