@phdthesis{Richter2021,
  author    = {Richter, Enrico Christian},
  title     = {Das letzte Kapitel des deutschen Zionismus},
  doi       = {10.25932/publishup-61575},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-615756},
  school      = {Universit{\"a}t Potsdam},
  pages     = {447},
  year      = {2021},
  abstract  = {Die Geschichtsschreibung terminiert das Ende des deutschen Zionismus bisher mit dem NS-Verbot der Zionistischen Vereinigung f{\"u}r Deutschland im Zuge des Novemberpogroms 1938. Zu diesem Zeitpunkt hatte er aber von seinem geographischen Kontext entgrenzt, in Erez Israel bereits neue Wurzeln geschlagen. Zionisten aus Deutschland schickten sich nun an, mit ihrem spezifischen Erfahrungshorizont und Wertemaßstab und mitgebrachtem ideologischen R{\"u}stzeug die Entwicklung des j{\"u}dischen Nationalheims mitzugestalten und einer umfassenden {\"o}konomischen, kulturellen und politischen Akkulturation der deutschen Alijah den Weg zu bahnen. Entgegen aller zionistischen Theorie gr{\"u}ndeten sie auf landsmannschaftlicher Basis im Jahr 1932 die Selbsthilfeorganisation Hitachduth Olej Germania und w{\"a}hrend des Weltkrieges die Partei Alija Chadascha. Die Dissertation beinhaltet die Gesamtschau des deutschen Zionismus in seiner letzten Phase in den Jahren 1932 bis 1948; zugleich beleuchtet sie die Geschichte der etwa 60.000 in Pal{\"a}stina eingewanderten Juden aus Deutschland in der f{\"u}r diese Abhandlung relevanten Zeitperiode. Im ersten Teil wird in chronologischer Folge die 1932 beginnende letztmalige Sammlung und Neuformierung des deutschen Zionismus in seiner neu-alten Heimat dargestellt. Wenn man so will, die formativen Jahre im personellen, organisatorischen und ideologisch-politischen Sinne, die schließlich nach dem fast g{\"a}nzlichen Scheitern der politischen Integration der deutschen Alijah mit der - in der R{\"u}ckschau - fast zwangsl{\"a}ufig erscheinenden Begr{\"u}ndung der Alija Chadascha ihren Abschluss fanden. Im zweiten Teil werden die Positionen der deutschen Zionisten zu den existenziellen Fragen der j{\"u}dischen Gemeinschaft in Pal{\"a}stina, hebr{\"a}isch Jischuw genannt, in der im Fokus stehenden Zeitperiode dargestellt. Im Einzelnen handelt es sich erstens um die Einwanderungsfrage, die untrennbar verbunden war mit der in der zionistischen Theorie unabdingbaren Forderung nach der Erlangung einer j{\"u}dischen Majorit{\"a}t in Pal{\"a}stina; zweitens um die der staatlichen Ausgestaltung des zuk{\"u}nftigen j{\"u}dischen Gemeinwesens und drittens um die Frage der ad{\"a}quaten Reaktion des Jischuw auf die Schoah. In diese jeweils in separaten Kapiteln behandelten Themenkomplexe wird die Frage nach dem anzustrebenden Verh{\"a}ltnis zur britischen Mandatsmacht mit einfließen. Hieran mussten die deutschen Zionisten ihr mitgebrachtes geistig-ideologisches R{\"u}stzeug einem Praxistest unterziehen und nach realpolitischen Antworten suchen. Dem kometenhaften Aufstieg der weiterhin landsmannschaftlich gepr{\"a}gten Alija Chadascha folgte dann in den ersten Nachkriegsjahren ein ebenso rapider Zerfall. Einige Monate nach der Staatsgr{\"u}ndung Israels l{\"o}ste sie sich dann sang- und klanglos auf und das Gros ihrer Aktivisten integrierte sich in das Parteiengef{\"u}ge des neuen Staates. Der deutsche Zionismus als politische Bewegung kam nun wirklich an sein Ende. Diese Abhandlung wird somit zum einen den Kampf der deutschen Alijah um gesellschaftliche Anerkennung und politische Partizipation im Jischuw nachzeichnen und zum anderen eine geistig-ideologische Verortung des deutschen Zionismus in seiner letzten Phase vollziehen und Tendenzen der ideologischen Neuausrichtung offenlegen. Dar{\"u}ber hinaus werden in der Historiographie vorhandene Allgemeinpl{\"a}tze wie die fast allseits anerkannte These vom Scheitern der deutschen Zionisten in der neuen Heimat einer {\"U}berpr{\"u}fung unterzogen. Die letzte vorhandene Leerstelle im wissenschaftlichen Kanon zur mehr als 50-j{\"a}hrigen Geschichte des deutschen Zionismus wird somit geschlossen.},
  language  = {de}
}
@phdthesis{Antonelli2021,
  author    = {Antonelli, Andrea},
  title     = {Accurate waveform models for gravitational-wave astrophysics: synergetic approaches from analytical relativity},
  doi       = {10.25932/publishup-57667},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-576671},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XII, 259, LXXV},
  year      = {2021},
  abstract  = {Gravitational-wave (GW) astrophysics is a field in full blossom. Since the landmark detection of GWs from a binary black hole on September 14th 2015, fifty-two compact-object binaries have been reported by the LIGO-Virgo collaboration. Such events carry astrophysical and cosmological information ranging from an understanding of how black holes and neutron stars are formed, what neutron stars are composed of, how the Universe expands, and allow testing general relativity in the highly-dynamical strong-field regime. It is the goal of GW astrophysics to extract such information as accurately as possible. Yet, this is only possible if the tools and technology used to detect and analyze GWs are advanced enough. A key aspect of GW searches are waveform models, which encapsulate our best predictions for the gravitational radiation under a certain set of parameters, and that need to be cross-correlated with data to extract GW signals. Waveforms must be very accurate to avoid missing important physics in the data, which might be the key to answer the fundamental questions of GW astrophysics. The continuous improvements of the current LIGO-Virgo detectors, the development of next-generation ground-based detectors such as the Einstein Telescope or the Cosmic Explorer, as well as the development of the Laser Interferometer Space Antenna (LISA), demand accurate waveform models. While available models are enough to capture the low spins, comparable-mass binaries routinely detected in LIGO-Virgo searches, those for sources from both current and next-generation ground-based and spaceborne detectors must be accurate enough to detect binaries with large spins and asymmetry in the masses. Moreover, the thousands of sources that we expect to detect with future detectors demand accurate waveforms to mitigate biases in the estimation of signals' parameters due to the presence of a foreground of many sources that overlap in the frequency band. This is recognized as one of the biggest challenges for the analysis of future-detectors' data, since biases might hinder the extraction of important astrophysical and cosmological information from future detectors' data. In the first part of this thesis, we discuss how to improve waveform models for binaries with high spins and asymmetry in the masses. In the second, we present the first generic metrics that have been proposed to predict biases in the presence of a foreground of many overlapping signals in GW data. For the first task, we will focus on several classes of analytical techniques. Current models for LIGO and Virgo studies are based on the post-Newtonian (PN, weak-field, small velocities) approximation that is most natural for the bound orbits that are routinely detected in GW searches. However, two other approximations have risen in prominence, the post-Minkowskian (PM, weak- field only) approximation natural for unbound (scattering) orbits and the small-mass-ratio (SMR) approximation typical of binaries in which the mass of one body is much bigger than the other. These are most appropriate to binaries with high asymmetry in the masses that challenge current waveform models. Moreover, they allow one to "cover" regions of the parameter space of coalescing binaries, thereby improving the interpolation (and faithfulness) of waveform models. The analytical approximations to the relativistic two-body problem can synergically be included within the effective-one-body (EOB) formalism, in which the two-body information from each approximation can be recast into an effective problem of a mass orbiting a deformed Schwarzschild (or Kerr) black hole. The hope is that the resultant models can cover both the low-spin comparable-mass binaries that are routinely detected, and the ones that challenge current models. The first part of this thesis is dedicated to a study about how to best incorporate information from the PN, PM, SMR and EOB approaches in a synergistic way. We also discuss how accurate the resulting waveforms are, as compared against numerical-relativity (NR) simulations. We begin by comparing PM models, whether alone or recast in the EOB framework, against PN models and NR simulations. We will show that PM information has the potential to improve currently-employed models for LIGO and Virgo, especially if recast within the EOB formalism. This is very important, as the PM approximation comes with a host of new computational techniques from particle physics to exploit. Then, we show how a combination of PM and SMR approximations can be employed to access previously-unknown PN orders, deriving the third subleading PN dynamics for spin-orbit and (aligned) spin1-spin2 couplings. Such new results can then be included in the EOB models currently used in GW searches and parameter estimation studies, thereby improving them when the binaries have high spins. Finally, we build an EOB model for quasi-circular nonspinning binaries based on the SMR approximation (rather than the PN one as usually done). We show how this is done in detail without incurring in the divergences that had affected previous attempts, and compare the resultant model against NR simulations. We find that the SMR approximation is an excellent approximation for all (quasi-circular nonspinning) binaries, including both the equal-mass binaries that are routinely detected in GW searches and the ones with highly asymmetric masses. In particular, the SMR-based models compare much better than the PN models, suggesting that SMR-informed EOB models might be the key to model binaries in the future. In the second task of this thesis, we work within the linear-signal ap- proximation and describe generic metrics to predict inference biases on the parameters of a GW source of interest in the presence of confusion noise from unfitted foregrounds and from residuals of other signals that have been incorrectly fitted out. We illustrate the formalism with simple (yet realistic) LISA sources, and demonstrate its validity against Monte-Carlo simulations. The metrics we describe pave the way for more realistic studies to quantify the biases with future ground-based and spaceborne detectors.},
  language  = {en}
}
@phdthesis{Tung2021,
  author    = {Tung, Wing Tai},
  title     = {Polymeric fibrous scaffold on macro/microscale towards tissue regeneration},
  school      = {Universit{\"a}t Potsdam},
  year      = {2021},
  language  = {en}
}
@phdthesis{Heinzel2021,
  author    = {Heinzel, Mirko Noa},
  title     = {World Bank staff and project implementation},
  year      = {2021},
  language  = {en}
}
@phdthesis{Uflewski2021,
  author    = {Uflewski, Michal},
  title     = {Characterizing the regulation of proton antiport across the thylakoid membrane},
  school      = {Universit{\"a}t Potsdam},
  pages     = {122},
  year      = {2021},
  abstract  = {Die Energie, die zum Antrieb photochemischer Reaktionen ben{\"o}tigt wird, stammt aus der Ladungstrennung an der Thylakoidmembran. Aufrgrund des Unterschieds in der Protonenkonzentration zwischen dem Stroma der Chloroplasten und dem Thylakoidlumen wird eine Protonenmotorische Kraft (pmf) erzeugt. Die pmf setzt sich aus dem Protonengradienten (ΔpH) und dem Membranpotential (ΔΨ) zusammen, die gemeinsam die ATP-Synthese antreiben. In der Natur schwankt die Energiemenge, die die Photosynthese antreibt, aufgrund h{\"a}ufiger {\"A}nderungen der Lichtintensit{\"a}t. Der Thylakoid-Ionentransport kann den Energiefluss durch einen Photosyntheseapparat an die Lichtverf{\"u}gbarkeit anpassen, indem er die pmf-Zusammensetzung ver{\"a}ndert. Die Dissipation von ΔΨ verringert die Ladungsrekombination am Photosystem II, so dass ein Anstieg der ΔpH-Komponente eine R{\"u}ckkopplung zur Herabregulierung der Photosynthese ausl{\"o}sen kann. Der durch den K+-Austausch-Antiporter 3 (KEA3) gesteuerte K+/H+-Antiport reduziert den ΔpH-Anteil von pmf und d{\"a}mpft dadurch das nicht-photochemische Quenching (NPQ). Infolgedessen erh{\"o}ht sich die Photosyntheseeffizienz beim {\"U}bergang zu geringerer Lichtintensit{\"a}t. Ziel dieser Arbeit war es, Antworten auf Fragen zur Regulierung der KEA3-Aktivit{\"a}t und ihrer Rolle in der Pflanzenentwicklung zu finden. Die vorgestellten Daten zeigen, dass KEA3 in Pflanzen, denen der Chloroplasten-ATP-Synthase-Assembly-Faktor CGL160 fehlt und die eine verminderte ATP-Synthase-Aktivit{\"a}t aufweisen, eine zentrale Rolle bei der Regulierung der Photosynthese und des Pflanzenwachstums unter station{\"a}ren Bedingungen spielt. Das Fehlen von KEA3 in der cgl160-Mutante f{\"u}hrt zu einer starken Beeintr{\"a}chtigung des Wachstums, da die Photosynthese aufgrund des erh{\"o}hten pH-abh{\"a}ngigen NPQs und des verringerten Elektronenflusses durch den Cytochrom b6f-Komplex eingeschr{\"a}nkt ist. Die {\"U}berexpression von KEA3 in der cgl160-Mutante erh{\"o}ht die Ladungsrekombination im Photosystem II und f{\"o}rdert die Photosynthese. In Zeiten geringer ATP-Synthase-Aktivit{\"a}t profitieren die Pflanzen also von der KEA3-Aktivit{\"a}t. KEA3 unterliegt einer Dimerisierung {\"u}ber seinen regulatorischen C-Terminus (RCT). Der RCT reagiert auf Ver{\"a}nderungen der Lichtintensit{\"a}t, da die Pflanzen, die KEA3 ohne diese Dom{\"a}ne exprimieren, einen reduzierten Lichtschutzmechanismus bei Lichtintensit{\"a}tsschwankungen aufweisen. Allerdings fixieren diese Pflanzen w{\"a}hrend der Photosynthese-Induktionsphase mehr Kohlenstoff als Gegenleistung f{\"u}r einen langfristigen Photoprotektor, was die regulierende Rolle von KEA3 in der Pflanzenentwicklung zeigt. Der KEA3-RCT ist dem Thylakoidstroma zugewandt, so dass seine Regulierung von lichtinduzierten Ver{\"a}nderungen in der Stroma-Umgebung abh{\"a}ngt. Die Regulierung der KEA3-Aktivit{\"a}t {\"u}berschneidet sich mit den pH-{\"A}nderungen im Stroma, die bei Lichtschwankungen auftreten. Es hat sich gezeigt, dass ATP und ADP eine Affinit{\"a}t zum heterolog exprimierten KEA3 RCT haben. Eine solche Wechselwirkung verursacht Konformations{\"a}nderungen in der RCT-Struktur. Die Faltung der RCT-Liganden-Interaktion h{\"a}ngt vom pH-Wert der Umgebung ab. Mit einer Kombination aus Bioinformatik und In-vitro-Ansatz wurde die ATP-Bindungsstelle am RCT lokalisiert. Das Einf{\"u}gen einer Punktmutation in der KEA3-RCT Bindungsstelle in planta f{\"u}hrte zu einer Deregulierung der Antiporteraktivit{\"a}t beim {\"U}bergang zu wenig Licht. Die in dieser Arbeit vorgestellten Daten erm{\"o}glichten es uns, die Rolle von KEA3 bei der Anpassung der Photosynthese umfassender zu bewerten und Modelle zur Regulierung der KEA3-Aktivit{\"a}t w{\"a}hrend des {\"U}bergangs zwischen verschiedenen Lichtintensit{\"a}ten vorzuschlagen.},
  language  = {en}
}
@phdthesis{Sonat2021,
  author    = {Sonat, Duygu},
  title     = {Institutional change in the Turkish Social Assistance System},
  school      = {Universit{\"a}t Potsdam},
  pages     = {194},
  year      = {2021},
  language  = {en}
}
@phdthesis{Forster2021,
  author    = {Forster, Florian},
  title     = {Continuous microgravity monitoring of the Þeistareykir geothermal field (North Iceland)},
  doi       = {10.25932/publishup-54851},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-548517},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XVII, 164},
  year      = {2021},
  abstract  = {In my doctoral thesis, I examine continuous gravity measurements for monitoring of the geothermal site at Þeistareykir in North Iceland. With the help of high-precision superconducting gravity meters (iGravs), I investigate underground mass changes that are caused by operation of the geothermal power plant (i.e. by extraction of hot water and reinjection of cold water). The overall goal of this research project is to make a statement about the sustainable use of the geothermal reservoir, from which also the Icelandic energy supplier and power plant operator Landsvirkjun should benefit. As a first step, for investigating the performance and measurement stability of the gravity meters, in summer 2017, I performed comparative measurements at the gravimetric observatory J9 in Strasbourg. From the three-month gravity time series, I examined calibration, noise and drift behaviour of the iGravs in comparison to stable long-term time series of the observatory superconducting gravity meters. After preparatory work in Iceland (setup of gravity stations, additional measuring equipment and infrastructure, discussions with Landsvirkjun and meetings with the Icelandic partner institute ISOR), gravity monitoring at Þeistareykir was started in December 2017. With the help of the iGrav records of the initial 18 months after start of measurements, I carried out the same investigations (on calibration, noise and drift behaviour) as in J9 to understand how the transport of the superconducting gravity meters to Iceland may influence instrumental parameters. In the further course of this work, I focus on modelling and reduction of local gravity contributions at Þeistareykir. These comprise additional mass changes due to rain, snowfall and vertical surface displacements that superimpose onto the geothermal signal of the gravity measurements. For this purpose, I used data sets from additional monitoring sensors that are installed at each gravity station and adapted scripts for hydro-gravitational modelling. The third part of my thesis targets geothermal signals in the gravity measurements. Together with my PhD colleague Nolwenn Portier from France, I carried out additional gravity measurements with a Scintrex CG5 gravity meter at 26 measuring points within the geothermal field in the summers of 2017, 2018 and 2019. These annual time-lapse gravity measurements are intended to increase the spatial coverage of gravity data from the three continuous monitoring stations to the entire geothermal field. The combination of CG5 and iGrav observations, as well as annual reference measurements with an FG5 absolute gravity meter represent the hybrid gravimetric monitoring method for Þeistareykir. Comparison of the gravimetric data to local borehole measurements (of groundwater levels, geothermal extraction and injection rates) is used to relate the observed gravity changes to the actually extracted (and reinjected) geothermal fluids. An approach to explain the observed gravity signals by means of forward modelling of the geothermal production rate is presented at the end of the third (hybrid gravimetric) study. Further modelling with the help of the processed gravity data is planned by Landsvirkjun. In addition, the experience from time-lapse and continuous gravity monitoring will be used for future gravity measurements at the Krafla geothermal field 22 km south-east of Þeistareykir.},
  language  = {en}
}
@phdthesis{Topuz2021,
  author    = {Topuz, Birol},
  title     = {Social integration and religion},
  year      = {2021},
  language  = {en}
}
@phdthesis{StarkeLiebe2021,
  author    = {Starke-Liebe, Maja},
  title     = {Leonhard Franks Remigration im geteilten Deutschland der 1950er Jahre},
  series = {Epistemata : W{\"u}rzburger wissenschaftliche Schriften; Reihe Literaturwissenschaft},
  journal   = {Epistemata : W{\"u}rzburger wissenschaftliche Schriften; Reihe Literaturwissenschaft},
  number    = {948},
  publisher = {K{\"o}nigshausen \& Neumann},
  address   = {W{\"u}rzburg},
  isbn      = {978-3-82607562-9},
  pages     = {467},
  year      = {2021},
  abstract  = {Leonhard Frank (1882-1961) hat bereits ein an Erfahrungen reiches Leben hinter sich, als er 1950 nach Deutschland zur{\"u}ckkehrt. Das langj{\"a}hrige Exil l{\"a}sst der Schriftsteller nicht zuletzt aufgrund mangelnder Ver{\"o}ffentlichungs- und Verdienstm{\"o}glichkeiten sowie einer rigiden Immigrationsgesetzgebung in den USA hinter sich. Vor allem jedoch zieht es ihn in seine Heimat als das Land seiner Sprache zur{\"u}ck. Und nur hier weiß er sein Publikum, dessen Resonanz er als existenziell empfindet. In dieser Studie werden die Bem{\"u}hungen nachvollzogen, die ein w{\"a}hrend der Weimarer Republik renommierter und {\"o}konomisch erfolgreicher Autor nach dem erzwungenen Exil w{\"a}hrend der Zeit des Nationalsozialismus unternimmt, um als linker Schriftsteller seine Position innerhalb der besonderen literarischen und kulturpolitischen Bedingungen in der BRD und der DDR im Jahrzehnt der 1950er Jahre zu finden. Ausgehend von umfangreichen Archivmaterialien werden die Lebens- und Arbeitsumst{\"a}nde Franks in seinem letzten Lebensjahrzehnt in die jeweiligen biographischen, sozialen, politischen und kulturellen Kontexte gesetzt. Besondere Aufmerksamkeit erf{\"a}hrt dabei die Besonderheit, dass Frank als B{\"u}rger der Bundesrepublik fortdauernde Beziehungen zu Institutionen und Personen in der DDR unterhielt. Aus dieser Konstellation resultiert eingedenk der politisch-historischen Prozesse, in die sie sich einbettete, ein Spannungsfeld, dessen Spezifika transparent gemacht werden.},
  language  = {de}
}
@phdthesis{Canil2021,
  author    = {Canil, Laura},
  title     = {Tuning Interfacial Properties in Perovskite Solar Cells through Defined Molecular Assemblies},
  doi       = {10.25932/publishup-54633},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-546333},
  school      = {Universit{\"a}t Potsdam},
  pages     = {vii, 157},
  year      = {2021},
  abstract  = {In the frame of a world fighting a dramatic global warming caused by human-related activities, research towards the development of renewable energies plays a crucial role. Solar energy is one of the most important clean energy sources and its role in the satisfaction of the global energy demand is set to increase. In this context, a particular class of materials captured the attention of the scientific community for its attractive properties: halide perovskites. Devices with perovskite as light-absorber saw an impressive development within the last decade, reaching nowadays efficiencies comparable to mature photovoltaic technologies like silicon solar cells. Yet, there are still several roadblocks to overcome before a wide-spread commercialization of this kind of devices is enabled. One of the critical points lies at the interfaces: perovskite solar cells (PSCs) are made of several layers with different chemical and physical features. In order for the device to function properly, these properties have to be well-matched. This dissertation deals with some of the challenges related to interfaces in PSCs, with a focus on the interface between the perovskite material itself and the subsequent charge transport layer. In particular, molecular assemblies with specific properties are deposited on the perovskite surface to functionalize it. The functionalization results in energy level alignment adjustment, interfacial losses reduction, and stability improvement. First, a strategy to tune the perovskite's energy levels is introduced: self-assembled monolayers of dipolar molecules are used to functionalize the surface, obtaining simultaneously a shift in the vacuum level position and a saturation of the dangling bonds at the surface. A shift in the vacuum level corresponds to an equal change in work function, ionization energy, and electron affinity. The direction of the shift depends on the direction of the collective interfacial dipole. The magnitude of the shift can be tailored by controlling the deposition parameters, such as the concentration of the solution used for the deposition. The shift for different molecules is characterized by several non-invasive techniques, including in particular Kelvin probe. Overall, it is shown that it is possible to shift the perovskite energy levels in both directions by several hundreds of meV. Moreover, interesting insights on the molecules deposition dynamics are revealed. Secondly, the application of this strategy in perovskite solar cells is explored. Devices with different perovskite compositions ("triple cation perovskite" and MAPbBr3) are prepared. The two resulting model systems present different energetic offsets at the perovskite/hole-transport layer interface. Upon tailored perovskite surface functionalization, the devices show a stabilized open circuit voltage (Voc) enhancement of approximately 60 meV on average for devices with MAPbBr3, while the impact is limited on triple-cation solar cells. This suggests that the proposed energy level tuning method is valid, but its effectiveness depends on factors such as the significance of the energetic offset compared to the other losses in the devices. Finally, the above presented method is further developed by incorporating the ability to interact with the perovskite surface directly into a novel hole-transport material (HTM), named PFI. The HTM can anchor to the perovskite halide ions via halogen bonding (XB). Its behaviour is compared to that of another HTM (PF) with same chemical structure and properties, except for the ability of forming XB. The interaction of perovskite with PFI and PF is characterized through UV-Vis, atomic force microscopy and Kelvin probe measurements combined with simulations. Compared to PF, PFI exhibits enhanced resilience against solvent exposure and improved energy level alignment with the perovskite layer. As a consequence, devices comprising PFI show enhanced Voc and operational stability during maximum-power-point tracking, in addition to hysteresis reduction. XB promotes the formation of a high-quality interface by anchoring to the halide ions and forming a stable and ordered interfacial layer, showing to be a particularly interesting candidate for the development of tailored charge transport materials in PSCs. Overall, the results exposed in this dissertation introduce and discuss a versatile tool to functionalize the perovskite surface and tune its energy levels. The application of this method in devices is explored and insights on its challenges and advantages are given. Within this frame, the results shed light on XB as ideal interaction for enhancing stability and efficiency in perovskite-based devices.},
  language  = {en}
}
@phdthesis{Zhao2021,
  author    = {Zhao, Yuhang},
  title     = {Synthesis and surface functionalization on plasmonic nanoparticles for optical applications},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VIII, 149},
  year      = {2021},
  abstract  = {This thesis focuses on the synthesis of novel functional materials based on plasmonic nanoparticles. Three systems with targeted surface modification and functionalization have been designed and synthesized, involving modified perylenediimide doped silica-coated silver nanowires, polydopamine or TiO2 coated gold-palladium nanorods and thiolated poly(ethylene glycol) (PEG-SH)/dodecanethiol (DDT) modified silver nanospheres. Their possible applications as plasmonic resonators, chiral sensors as well as photo-catalysts have been studied. In addition, the interaction between silver nanospheres and 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) molecules has also been investigated in detail. In the first part of the thesis, surface modification on Ag nanowires (NWs) with optimized silica coating through a modified St{\"o}ber method has been firstly conducted, employing sodium hydroxide (NaOH) to replace ammonia solution (NH4OH). The coated silver nanowires with a smooth silica shell have been investigated by single-particle dark-field scattering spectroscopy, transmission electron microscopy and electron-energy loss spectroscopy to characterize the morphologies and structural components. The silica-coated silver nanowires can be further functionalized with fluorescent molecules in the silica shell via a facile one-step coating method. The as-synthesized nanowire is further coupled with a gold nanosphere by spin-coating for the application of the sub-diffractional chiral sensor for the first time. The exciton-plasmon-photon interconversion in the system eases the signal detection in the perfectly matched 1D nanostructure and contributes to the high contrast of the subwavelength chiral sensing for the polarized light. In the second part of the thesis, dumbbell-shaped Au-Pd nanorods coated with a layer of polydopamine (PDA) or titanium dioxide (TiO2) have been constructed. The PDA- and TiO2- coated Au-Pd nanorods show a strong photothermal conversion performance under NIR illumination. Moreover, the catalytic performance of the particles has been investigated using the reduction of 4-nitrophenol (4-NP) as the model reaction. Under light irradiation, the PDA-coated Au-Pd nanorods exhibit a superior catalytic activity by increasing the reaction rate constant of 3 times. The Arrhenius-like behavior of the reaction with similar activation energies in the presence and absence of light irradiation indicates the photoheating effect to be the dominant mechanism of the reaction acceleration. Thus, we attribute the enhanced performance of the catalysis to the strong photothermal effect that is driven by the optical excitation of the gold surface plasmon as well as the synergy with the PDA layer. In the third part, the kinetic study on the adsorption of 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquino-dimethane (F4TCNQ) on the surface of Ag nanoparticles (Ag NPs) in chloroform has been reported in detail. Based on the results obtained from the UV-vis-NIR absorption spectroscopy, cryogenic transmission electron microscopy (cryo-TEM), scanning nano-beam electron diffraction (NBED) and electron energy loss spectroscopy (EELS), a two-step interaction kinetics has been proposed for the Ag NPs and F4TCNQ molecules. It includes the first step of electron transfer from Ag NPs to F4TCNQ indicated by the ionization of F4TCNQ, and the second step of the formation of Ag-F4TCNQ complex. The whole process has been followed via UV-vis-NIR absorption spectroscopy, which reveals distinct kinetics at two stages: the instantaneous ionization and the long-term complex formation. The kinetics and the influence of the molar ratio of Ag NPs/F4TCNQ molecules on the interaction between Ag NPs and F4TCNQ molecules in the organic solution are reported herein for the first time. Furthermore, the control experiment with silica-coated Ag NPs indicates that the charge transfer at the surface between Ag NPs and F4TCNQ molecules has been prohibited by a silica layer of 18 nm.},
  language  = {en}
}
@phdthesis{Andjelkovic2021,
  author    = {Andjelkovic, Marko},
  title     = {A methodology for characterization, modeling and mitigation of single event transient effects in CMOS standard combinational cells},
  doi       = {10.25932/publishup-53484},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-534843},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxiv, 216},
  year      = {2021},
  abstract  = {With the downscaling of CMOS technologies, the radiation-induced Single Event Transient (SET) effects in combinational logic have become a critical reliability issue for modern integrated circuits (ICs) intended for operation under harsh radiation conditions. The SET pulses generated in combinational logic may propagate through the circuit and eventually result in soft errors. It has thus become an imperative to address the SET effects in the early phases of the radiation-hard IC design. In general, the soft error mitigation solutions should accommodate both static and dynamic measures to ensure the optimal utilization of available resources. An efficient soft-error-aware design should address synergistically three main aspects: (i) characterization and modeling of soft errors, (ii) multi-level soft error mitigation, and (iii) online soft error monitoring. Although significant results have been achieved, the effectiveness of SET characterization methods, accuracy of predictive SET models, and efficiency of SET mitigation measures are still critical issues. Therefore, this work addresses the following topics: (i) Characterization and modeling of SET effects in standard combinational cells, (ii) Static mitigation of SET effects in standard combinational cells, and (iii) Online particle detection, as a support for dynamic soft error mitigation. Since the standard digital libraries are widely used in the design of radiation-hard ICs, the characterization of SET effects in standard cells and the availability of accurate SET models for the Soft Error Rate (SER) evaluation are the main prerequisites for efficient radiation-hard design. This work introduces an approach for the SPICE-based standard cell characterization with the reduced number of simulations, improved SET models and optimized SET sensitivity database. It has been shown that the inherent similarities in the SET response of logic cells for different input levels can be utilized to reduce the number of required simulations. Based on characterization results, the fitting models for the SET sensitivity metrics (critical charge, generated SET pulse width and propagated SET pulse width) have been developed. The proposed models are based on the principle of superposition, and they express explicitly the dependence of the SET sensitivity of individual combinational cells on design, operating and irradiation parameters. In contrast to the state-of-the-art characterization methodologies which employ extensive look-up tables (LUTs) for storing the simulation results, this work proposes the use of LUTs for storing the fitting coefficients of the SET sensitivity models derived from the characterization results. In that way the amount of characterization data in the SET sensitivity database is reduced significantly. The initial step in enhancing the robustness of combinational logic is the application of gate-level mitigation techniques. As a result, significant improvement of the overall SER can be achieved with minimum area, delay and power overheads. For the SET mitigation in standard cells, it is essential to employ the techniques that do not require modifying the cell structure. This work introduces the use of decoupling cells for improving the robustness of standard combinational cells. By insertion of two decoupling cells at the output of a target cell, the critical charge of the cell's output node is increased and the attenuation of short SETs is enhanced. In comparison to the most common gate-level techniques (gate upsizing and gate duplication), the proposed approach provides better SET filtering. However, as there is no single gate-level mitigation technique with optimal performance, a combination of multiple techniques is required. This work introduces a comprehensive characterization of gate-level mitigation techniques aimed to quantify their impact on the SET robustness improvement, as well as introduced area, delay and power overhead per gate. By characterizing the gate-level mitigation techniques together with the standard cells, the required effort in subsequent SER analysis of a target design can be reduced. The characterization database of the hardened standard cells can be utilized as a guideline for selection of the most appropriate mitigation solution for a given design. As a support for dynamic soft error mitigation techniques, it is important to enable the online detection of energetic particles causing the soft errors. This allows activating the power-greedy fault-tolerant configurations based on N-modular redundancy only at the high radiation levels. To enable such a functionality, it is necessary to monitor both the particle flux and the variation of particle LET, as these two parameters contribute significantly to the system SER. In this work, a particle detection approach based on custom-sized pulse stretching inverters is proposed. Employing the pulse stretching inverters connected in parallel enables to measure the particle flux in terms of the number of detected SETs, while the particle LET variations can be estimated from the distribution of SET pulse widths. This approach requires a purely digital processing logic, in contrast to the standard detectors which require complex mixed-signal processing. Besides the possibility of LET monitoring, additional advantages of the proposed particle detector are low detection latency and power consumption, and immunity to error accumulation. The results achieved in this thesis can serve as a basis for establishment of an overall soft-error-aware database for a given digital library, and a comprehensive multi-level radiation-hard design flow that can be implemented with the standard IC design tools. The following step will be to evaluate the achieved results with the irradiation experiments.},
  language  = {en}
}
@phdthesis{Zhao2021,
  author    = {Zhao, Xueru},
  title     = {Palaeoclimate and palaeoenvironment evolution from the last glacial maximum into the early holocene (23-8 ka BP) derived from Lago Grande di Monticchio sediment record (S Italy)},
  pages     = {123},
  year      = {2021},
  language  = {en}
}
@phdthesis{MathieuGaedke2021,
  author    = {Mathieu-Gaedke, Maria},
  title     = {Grafting-to and grafting-from proteins - synthesis and characterization of protein-polymer conjugates on the way to biohybrid membrane materials},
  doi       = {10.25932/publishup-54292},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-542921},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XVIII, 149},
  year      = {2021},
  abstract  = {The incorporation of proteins in artificial materials such as membranes offers great opportunities to avail oneself the miscellaneous qualities of proteins and enzymes perfected by nature over millions of years. One possibility to leverage proteins is the modification with artificial polymers. To obtain such protein-polymer conjugates, either a polymer can be grown from the protein surface (grafting-from) or a pre-synthesized polymer attached to the protein (grafting-to). Both techniques were used to synthesize conjugates of different proteins with thermo-responsive polymers in this thesis. First, conjugates were analyzed by protein NMR spectroscopy. Typical characterization techniques for conjugates can verify the successful conjugation and give hints on the secondary structure of the protein. However, the 3-dimensional structure, being highly important for the protein function, cannot be probed by standard techniques. NMR spectroscopy is a unique method allowing to follow even small alterations in the protein structure. A mutant of the carbohydrate binding module 3b (CBM3bN126W) was used as model protein and functionalized with poly(N-isopropylacrylamide). Analysis of conjugates prepared by grafting-to or grafting-from revealed a strong impact of conjugation type on protein folding. Whereas conjugates prepared by grafting a pre-formed polymer to the protein resulted in complete preservation of protein folding, grafting the polymer from the protein surface led to (partial) disruption of the protein structure. Next, conjugates of bovine serum albumin (BSA) as cheap and easily accessible protein were synthesized with PNIPAm and different oligoethylene glycol (meth)acrylates. The obtained protein-polymer conjugates were analyzed by an in-line combination of size exclusion chromatography and multi-angle laser light scattering (SEC-MALS). This technique is particular advantageous to determine molar masses, as no external calibration of the system is needed. Different SEC column materials and operation conditions were tested to evaluate the applicability of this system to determine absolute molar masses and hydrodynamic properties of heterogeneous conjugates prepared by grafting-from and grafting-to. Hydrophobic and non-covalent interactions of conjugates lead to error-prone values not in accordance to expected molar masses based on conversions and extents of modifications. As alternative to this method, conjugates were analyzed by sedimentation velocity analytical ultracentrifugation (SV-AUC) to gain insights in the hydrodynamic properties and how they change after conjugation. Within a centrifugal field, a sample moves and fractionates according to the mass, density, and shape of its individual components. Conjugates of BSA with PNIPAm were analyzed below and above the cloud point temperature of the thermo-responsive polymer component. It was identified that the polymer characteristics were transferred to the conjugate molecule which than showed a decreased ideality - defined as increased deviation from a perfect sphere model - below and increased ideality above the cloud point temperature. This effect can be attributed to an arrangement of the polymer chain pointing towards the solvent (expanded state) or snuggling around the protein surface depending on the applied temperature. The last project dealt with the synthesis of ferric hydroxamate uptake protein component A (FhuA)-polymer conjugates as building blocks for novel membrane materials. The shape of FhuA can be described as barrel and removal of a cork domain inside the protein results in a passive channel aimed to be utilized as pores in the membrane system. The polymer matrix surrounding the membrane protein is composed of a thermo-responsive and a UV-crosslinkable part. Therefore, an external trigger for covalent immobilization of these building blocks in the membrane and switchability of the membrane between different states was incorporated. The overall performance of membranes prepared by a drying-mediated self-assembly approach was evaluated by permeability and size exclusion experiments. The obtained membranes displayed an insufficiency in interchain crosslinking and therefore a lack in performance. Furthermore, the aimed switch between a hydrophilic and hydrophobic state of the polymer matrix did not occur. Correspondingly, size exclusion experiments did not result in a retention of analytes larger than the pores defined by the dimension of the used FhuA variant. Overall, different paths to generate protein-polymer conjugates by either grafting-from or grafting-to the protein surface were presented paving the way to the generation of new hybrid materials. Different analytical methods were utilized to describe the folding and hydrodynamic properties of conjugates providing a deeper insight in the overall characteristics of these seminal building blocks.},
  language  = {en}
}
@phdthesis{Yan2021,
  author    = {Yan, Wan},
  title     = {Shape-Memory effects of thermoplatic multiblock copolymers with overlapping thermal transitions},
  year      = {2021},
  language  = {en}
}
@phdthesis{Herpich2021,
  author    = {Herpich, Catrin},
  title     = {Fibroblast growth factor 21 and its association with nutritional stimuli in older age},
  school      = {Universit{\"a}t Potsdam},
  pages     = {75},
  year      = {2021},
  abstract  = {Fibroblast growth differentiation factor 21 (FGF21) is known as a pivotal regulator of the glucose and lipid metabolism. As such, it is considered beneficial and has even been labelled a longevity hormone. Nevertheless, recent observational studies have shown that FGF21 is increased in higher age with possible negative effects such as loss of lean and bone mass as well as decreased survival. Hepatic FGF21 secretion can be induced by various nutritional stimuli such as starvation, high carbohydrate and fat intake as well as protein deficiency.. So far it is still unclear whether the FGF21 response to different macronutrients is altered in older age. An altered response would potentially contribute to explain the higher FGF21 concentrations found in older age. In this publication-based doctoral dissertation, a cross-sectional study as well as a dietary challenge were conducted to investigate the influence of nutrition on FGF21 concentrations and response in older age. In a cross-sectional study, FGF21 concentrations were assessed in older patients with and without cachexia anorexia syndrome anorexia syndrome compared to an older community-dwelling control group. Cachexia anorexia syndrome is a multifactorial syndrome frequently occurring in old age or in the context of an underlying disease. It is characterized by a severe involuntary weight loss, loss of appetite (anorexia) and reduced food intake, therefore representing a state of severe nutrient deficiency, in some aspects similar to starvation. The highest FGF21 concentrations were found in patients with cachexia anorexia syndrome. Moreover, FGF21 was positively correlated with weight loss and loss of appetite. In addition, cachexia anorexia syndrome itself was associated with FGF21 independent of sex, age and body mass index. As cachectic patients presumably exhibit protein malnutrition and FGF21 has been proposed a marker for protein insufficiency, the higher levels of FGF21 in patients with cachexia anorexia syndrome might be partly explained by insufficient protein intake. In order to investigate the acute response of FGF21 to different nutritional stimuli, a dietary challenge with a parallel group design was conducted. Here, healthy older (65-85 years) and younger (18-35 years) adults were randomized to one of four test meals: a dextrose drink, a high carbohydrate, high fat or high protein meal. Over the course of four hours, postprandial FGF21 concentrations (dynamics) were assessed and the FGF21 response (incremental area under the curve) to each test meal was examined.. In a sub-group of older and younger women, also the adiponectin response was investigated, as adiponectin is a known mediator of FGF21 effects on glucose and lipid metabolism. The dietary meal challenge revealed that dextrose and high carbohydrate intake result in higher FGF21 concentrations after four hours in older adults. This was partly explained by higher postprandial glucose concentrations in the old. For high fat ingestion no age differences were found. For the first time, acute FGF21 response to high protein intake was shown. Here, protein ingestion resulted in lower FGF21 concentrations in younger compared to older adults. Furthermore, sufficient protein intake, according to age-dependent recommendations, of the previous day, was associated with lower FGF21 concentrations in both age groups. The higher FGF21 response to dextrose ingestion resulted in a higher adiponectin response in older women, independent of fat mass, insulin resistance, triglyceride concentrations, inflammation and oxidative stress. Following the high fat meal, adiponectin concentrations declined in older women. Adiponectin response was not affected by meal composition in younger women. In summary, this thesis showed a positive association of FGF21 and cachexia anorexia syndrome with concomitant anorexia in older patients. Regarding the acute FGF21 response, a higher response following dextrose and carbohydrate ingestion was found in older compared with younger subjects. This might be attributed to a higher glucose response in older age. Furthermore, it was shown that the higher FGF21 response after dextrose ingestion possibly contributes to a higher adiponectin response in older women, independent of potential metabolic and inflammatory confounders. Acute protein ingestion resulted in a significant decrease in FGF21 concentrations. Moreover, protein intake of the previous day was inversely associated with fasting FGF21 concentrations. This might explain why FGF21 concentrations are higher in cachexia anorexia syndrome. These results therefore support the role of FGF21 as a sensor of protein restriction.},
  language  = {en}
}
@phdthesis{Dahmani2021,
  author    = {Dahmani, Ismail},
  title     = {Influenza A virus matrix protein M1},
  doi       = {10.25932/publishup-52740},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-527409},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XI, 147},
  year      = {2021},
  abstract  = {Influenza A virus (IAV) is a pathogen responsible for severe seasonal epidemics threatening human and animal populations every year. During the viral assembly process in the infected cells, the plasma membrane (PM) has to bend in localized regions into a vesicle towards the extracellular side. Studies in cellular models have proposed that different viral proteins might be responsible for inducing membrane curvature in this context (including M1), but a clear consensus has not been reached. M1 is the most abundant protein in IAV particles. It plays an important role in virus assembly and budding at the PM. M1 is recruited to the host cell membrane where it associates with lipids and other viral proteins. However, the details of M1 interactions with the cellular PM, as well as M1-mediated membrane bending at the budozone, have not been clarified. In this work, we used several experimental approaches to analyze M1-lipids and M1-M1 interactions. By performing SPR analysis, we quantified membrane association for full-length M1 and different genetically engineered M1 constructs (i.e., N- and C-terminally truncated constructs and a mutant of the polybasic region). This allowed us to obtain novel information on the protein regions mediating M1 binding to membranes. By using fluorescence microscopy, cryogenic transmission electron microscopy (cryo-TEM), and three-dimensional (3D) tomography (cryo-ET), we showed that M1 is indeed able to cause membrane deformation on vesicles containing negatively-charged lipids, in the absence of other viral components. Further, sFCS analysis proved that simple protein binding is not sufficient to induce membrane restructuring. Rather, it appears that stable M1-M1 interactions and multimer formation are required to alter the bilayer three-dimensional structure through the formation of a protein scaffold. Finally, to mimic the budding mechanism in cells that arise by the lateral organization of the virus membrane components on lipid raft domains, we created vesicles with lipid domains. Our results showed that local binding of M1 to spatial confined acidic lipids within membrane domains of vesicles led to local M1 inward curvature.},
  language  = {en}
}
@phdthesis{Saretia2021,
  author    = {Saretia, Shivam},
  title     = {Modulating ultrathin films of semi-crystalline oligomers by Langmuir technique},
  doi       = {10.25932/publishup-54210},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-542108},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XIII, 109},
  year      = {2021},
  abstract  = {Polymeric films and coatings derived from semi-crystalline oligomers are of relevance for medical and pharmaceutical applications. In this context, the material surface is of particular importance, as it mediates the interaction with the biological system. Two dimensional (2D) systems and ultrathin films are used to model this interface. However, conventional techniques for their preparation, such as spin coating or dip coating, have disadvantages, since the morphology and chain packing of the generated films can only be controlled to a limited extent and adsorption on the substrate used affects the behavior of the films. Detaching and transferring the films prepared by such techniques requires additional sacrificial or supporting layers, and free-standing or self supporting domains are usually of very limited lateral extension. The aim of this thesis is to study and modulate crystallization, melting, degradation and chemical reactions in ultrathin films of oligo(ε-caprolactone)s (OCL)s with different end-groups under ambient conditions. Here, oligomeric ultrathin films are assembled at the air-water interface using the Langmuir technique. The water surface allows lateral movement and aggregation of the oligomers, which, unlike solid substrates, enables dynamic physical and chemical interaction of the molecules. Parameters like surface pressure (π), temperature and mean molecular area (MMA) allow controlled assembly and manipulation of oligomer molecules when using the Langmuir technique. The π-MMA isotherms, Brewster angle microscopy (BAM), and interfacial infrared spectroscopy assist in detecting morphological and physicochemical changes in the film. Ultrathin films can be easily transferred to the solid silicon surface via Langmuir Schaefer (LS) method (horizontal substrate dipping). Here, the films transferred on silicon are investigated using atomic force microscopy (AFM) and optical microscopy and are compared to the films on the water surface. The semi-crystalline morphology (lamellar thicknesses, crystal number densities, and lateral crystal dimensions) is tuned by the chemical structure of the OCL end-groups (hydroxy or methacrylate) and by the crystallization temperature (Tc; 12 or 21 °C) or MMAs. Compression to lower MMA of ~2 {\AA}2, results in the formation of a highly crystalline film, which consists of tightly packed single crystals. Preparation of tightly packed single crystals on a cm2 scale is not possible by conventional techniques. Upon transfer to a solid surface, these films retain their crystalline morphology whereas amorphous films undergo dewetting. The melting temperature (Tm) of OCL single crystals at the water and the solid surface is found proportional to the inverse crystal thickness and is generally lower than the Tm of bulk PCL. The impact of OCL end-groups on melting behavior is most noticeable at the air-solid interface, where the methacrylate end-capped OCL (OCDME) melted at lower temperatures than the hydroxy end-capped OCL (OCDOL). When comparing the underlying substrate, melting/recrystallization of OCL ultrathin films is possible at lower temperatures at the air water interface than at the air-solid interface, where recrystallization is not visible. Recrystallization at the air-water interface usually occurs at a higher temperature than the initial Tc. Controlled degradation is crucial for the predictable performance of degradable polymeric biomaterials. Degradation of ultrathin films is carried out under acidic (pH ~ 1) or enzymatic catalysis (lipase from Pseudomonas cepcia) on the water surface or on a silicon surface as transferred films. A high crystallinity strongly reduces the hydrolytic but not the enzymatic degradation rate. As an influence of end-groups, the methacrylate end-capped linear oligomer, OCDME (~85 ± 2 \% end-group functionalization) hydrolytically degrades faster than the hydroxy end capped linear oligomer, OCDOL (~95 ± 3 \% end-group functionalization) at different temperatures. Differences in the acceleration of hydrolytic degradation of semi-crystalline films were observed upon complete melting, partial melting of the crystals, or by heating to temperatures close to Tm. Therefore, films of densely packed single crystals are suitable as barrier layers with thermally switchable degradation rates. Chemical modification in ultrathin films is an intricate process applicable to connect functionalized molecules, impart stability or create stimuli-sensitive cross-links. The reaction of end-groups is explored for transferred single crystals on a solid surface or amorphous monolayer at the air-water interface. Bulky methacrylate end-groups are expelled to the crystal surface during chain-folded crystallization. The density of end-groups is inversely proportional to molecular weight and hence very pronounced for oligomers. The methacrylate end-groups at the crystal surface, which are present at high concentration, can be used for further chemical functionalization. This is demonstrated by fluorescence microscopy after reaction with fluorescein dimethacrylate. The thermoswitching behavior (melting and recrystallization) of fluorescein functionalized single crystals shows the temperature-dependent distribution of the chemically linked fluorescein moieties, which are accumulated on the surfaces of crystals, and homogeneously dispersed when the crystals are molten. In amorphous monolayers at the air-water interface, reversible cross-linking of hydroxy-terminated oligo(ε-caprolactone) monolayers using dialdehyde (glyoxal) lead to the formation of 2D networks. Pronounced contraction in the area occurred for 2D OCL films in dependence of surface pressure and time indicating the reaction progress. Cross linking inhibited crystallization and retarded enzymatic degradation of the OCL film. Altering the subphase pH to ~2 led to cleavage of the covalent acetal cross-links. Besides as model systems, these reversibly cross-linked films are applicable for drug delivery systems or cell substrates modulating adhesion at biointerfaces.},
  language  = {en}
}
@phdthesis{Jentsch2021,
  author    = {Jentsch, Anna},
  title     = {Soil gas analytics in geothermal exploration and monitoring},
  doi       = {10.25932/publishup-54403},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-544039},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxxi, 162},
  year      = {2021},
  abstract  = {Major challenges during geothermal exploration and exploitation include the structural-geological characterization of the geothermal system and the application of sustainable monitoring concepts to explain changes in a geothermal reservoir during production and/or reinjection of fluids. In the absence of sufficiently permeable reservoir rocks, faults and fracture networks are preferred drilling targets because they can facilitate the migration of hot and/or cold fluids. In volcanic-geothermal systems considerable amounts of gas emissions can be released at the earth surface, often related to these fluid-releasing structures. In this thesis, I developed and evaluated different methodological approaches and measurement concepts to determine the spatial and temporal variation of several soil gas parameters to understand the structural control on fluid flow. In order to validate their potential as innovative geothermal exploration and monitoring tools, these methodological approaches were applied to three different volcanic-geothermal systems. At each site an individual survey design was developed regarding the site-specific questions. The first study presents results of the combined measurement of CO2 flux, ground temperatures, and the analysis of isotope ratios (δ13CCO2, 3He/4He) across the main production area of the Los Humeros geothermal field, to identify locations with a connection to its supercritical (T > 374◦C and P > 221 bar) geothermal reservoir. The results of the systematic and large-scale (25 x 200 m) CO2 flux scouting survey proved to be a fast and flexible way to identify areas of anomalous degassing. Subsequent sampling with high resolution surveys revealed the actual extent and heterogenous pattern of anomalous degassing areas. They have been related to the internal fault hydraulic architecture and allowed to assess favourable structural settings for fluid flow such as fault intersections. Finally, areas of unknown structurally controlled permeability with a connection to the superhot geothermal reservoir have been determined, which represent promising targets for future geothermal exploration and development. In the second study, I introduce a novel monitoring approach by examining the variation of CO2 flux to monitor changes in the reservoir induced by fluid reinjection. For that reason, an automated, multi-chamber CO2 flux system was deployed across the damage zone of a major normal fault crossing the Los Humeros geothermal field. Based on the results of the CO2 flux scouting survey, a suitable site was selected that had a connection to the geothermal reservoir, as identified by hydrothermal CO2 degassing and hot ground temperatures (> 50 °C). The results revealed a response of gas emissions to changes in reinjection rates within 24 h, proving an active hydraulic communication between the geothermal reservoir and the earth surface. This is a promising monitoring strategy that provides nearly real-time and in-situ data about changes in the reservoir and allows to timely react to unwanted changes (e.g., pressure decline, seismicity). The third study presents results from the Aluto geothermal field in Ethiopia where an area-wide and multi-parameter analysis, consisting of measurements of CO2 flux, 222Rn, and 220Rn activity concentrations and ground temperatures was conducted to detect hidden permeable structures. 222Rn and 220Rn activity concentrations are evaluated as a complementary soil gas parameter to CO2 flux, to investigate their potential to understand tectono-volcanic degassing. The combined measurement of all parameters enabled to develop soil gas fingerprints, a novel visualization approach. Depending on the magnitude of gas emissions and their migration velocities the study area was divided in volcanic (heat), tectonic (structures), and volcano-tectonic dominated areas. Based on these concepts, volcano-tectonic dominated areas, where hot hydrothermal fluids migrate along permeable faults, present the most promising targets for future geothermal exploration and development in this geothermal field. Two of these areas have been identified in the south and south-east which have not yet been targeted for geothermal exploitation. Furthermore, two unknown areas of structural related permeability could be identified by 222Rn and 220Rn activity concentrations. Eventually, the fourth study presents a novel measurement approach to detect structural controlled CO2 degassing, in Ngapouri geothermal area, New Zealand. For the first time, the tunable diode laser (TDL) method was applied in a low-degassing geothermal area, to evaluate its potential as a geothermal exploration method. Although the sampling approach is based on profile measurements, which leads to low spatial resolution, the results showed a link between known/inferred faults and increased CO2 concentrations. Thus, the TDL method proved to be a successful in the determination of structural related permeability, also in areas where no obvious geothermal activity is present. Once an area of anomalous CO2 concentrations has been identified, it can be easily complemented by CO2 flux grid measurements to determine the extent and orientation of the degassing segment. With the results of this work, I was able to demonstrate the applicability of systematic and area-wide soil gas measurements for geothermal exploration and monitoring purposes. In particular, the combination of different soil gases using different measurement networks enables the identification and characterization of fluid-bearing structures and has not yet been used and/or tested as standard practice. The different studies present efficient and cost-effective workflows and demonstrate a hands-on approach to a successful and sustainable exploration and monitoring of geothermal resources. This minimizes the resource risk during geothermal project development. Finally, to advance the understanding of the complex structure and dynamics of geothermal systems, a combination of comprehensive and cutting-edge geological, geochemical, and geophysical exploration methods is essential.},
  language  = {en}
}
@phdthesis{Schutjajew2021,
  author    = {Schutjajew, Konstantin},
  title     = {Electrochemical sodium storage in non-graphitizing carbons - insights into mechanisms and synthetic approaches towards high-energy density materials},
  doi       = {10.25932/publishup-54189},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-541894},
  school      = {Universit{\"a}t Potsdam},
  pages     = {v, 148},
  year      = {2021},
  abstract  = {To achieve a sustainable energy economy, it is necessary to turn back on the combustion of fossil fuels as a means of energy production and switch to renewable sources. However, their temporal availability does not match societal consumption needs, meaning that renewably generated energy must be stored in its main generation times and allocated during peak consumption periods. Electrochemical energy storage (EES) in general is well suited due to its infrastructural independence and scalability. The lithium ion battery (LIB) takes a special place, among EES systems due to its energy density and efficiency, but the scarcity and uneven geological occurrence of minerals and ores vital for many cell components, and hence the high and fluctuating costs will decelerate its further distribution. The sodium ion battery (SIB) is a promising successor to LIB technology, as the fundamental setup and cell chemistry is similar in the two systems. Yet, the most widespread negative electrode material in LIBs, graphite, cannot be used in SIBs, as it cannot store sufficient amounts of sodium at reasonable potentials. Hence, another carbon allotrope, non-graphitizing or hard carbon (HC) is used in SIBs. This material consists of turbostratically disordered, curved graphene layers, forming regions of graphitic stacking and zones of deviating layers, so-called internal or closed pores. The structural features of HC have a substantial impact of the charge-potential curve exhibited by the carbon when it is used as the negative electrode in an SIB. At defects and edges an adsorption-like mechanism of sodium storage is prevalent, causing a sloping voltage curve, ill-suited for the practical application in SIBs, whereas a constant voltage plateau of relatively high capacities is found immediately after the sloping region, which recent research attributed to the deposition of quasimetallic sodium into the closed pores of HC. Literature on the general mechanism of sodium storage in HCs and especially the role of the closed pore is abundant, but the influence of the pore geometry and chemical nature of the HC on the low-potential sodium deposition is yet in an early stage. Therefore, the scope of this thesis is to investigate these relationships using suitable synthetic and characterization methods. Materials of precisely known morphology, porosity, and chemical structure are prepared in clear distinction to commonly obtained ones and their impact on the sodium storage characteristics is observed. Electrochemical impedance spectroscopy in combination with distribution of relaxation times analysis is further established as a technique to study the sodium storage process, in addition to classical direct current techniques, and an equivalent circuit model is proposed to qualitatively describe the HC sodiation mechanism, based on the recorded data. The obtained knowledge is used to develop a method for the preparation of closed porous and non-porous materials from open porous ones, proving not only the necessity of closed pores for efficient sodium storage, but also providing a method for effective pore closure and hence the increase of the sodium storage capacity and efficiency of carbon materials. The insights obtained and methods developed within this work hence not only contribute to the better understanding of the sodium storage mechanism in carbon materials of SIBs, but can also serve as guidance for the design of efficient electrode materials.},
  language  = {en}
}