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Dissertation
Towards the investigation of ultrafast dynamics in chiral systems using free-electron lasers
(2024)
Chiral molecules are life’s building blocks, making the study of their ultrafast processes a pursuit across various fundamental research fields. The results presented in this dissertation contain methodological, technical and scientific advancements that pave the way for future time-resolved, site-specific investigations into chiral photochemistry of randomly orientated molecules, using photoelectron circular dichroism and free-electron lasers. The high-repetitionrate free-electron lasers EuXFEL and FLASH2 will soon ...
Dissertation
Context Awareness for Smartphone-Based Cooperative VRU Collision Avoidance
(2024)
Nach Angaben der Weltgesundheitsorganisation sterben weltweit noch immer jährlich rund 1,35 Millionen Menschen bei Verkehrsunfällen. Ungefähr 54% dieser Todesfälle ereignen sich unter ungeschützten Verkehrsteilnehmern wie Fußgängern, Radfahrern und Motorradfahrern. Fußgänger und Radfahrer machen dabei zusammen rund 26% aller Verkehrstoten aus. Im Gegensatz zu fahrzeugbasierten Kollisionsvermeidungssystemen setzen kooperative Systeme die Verwendung von mobilen Geräten wie Smartphones zur kontinuierlichen Erfassung von ...
Dissertation
The anatomy of velvet worms (Onychophora) as revealed by a multimethodological approach and three-dimensional reconstructions
(2024)
Onychophorans, or velvet worms, comprise a small group of worm-like, multi-legged terrestrial invertebrates. Since their discovery in 1826, these organisms have been investigated from different perspectives, particularly in the field of morphology—a discipline that provides the basis for functional and evolutionary inferences. Onychophorans are currently classified within Ecdysozoa (moulting animals) and form together with Tardigrada (water bears) and Arthropoda a clade named Panarthropoda. Therefore, onychophorans ...
Dissertation
Pentamethylcyclopentadienyl-Halbsandwich-Eisenkomplexe mit ungewöhnlichen Carbenliganden
(2024)
This dissertation project deals with the electronic properties of the pentamethylcyclopentadienyl halfsandwich iron complex with bis(trimethylsilyl)amido ligand ([Fe(Cp*)(HMDS)], HMDS = N(SiMe₃)₂) and its reactivity towards carbenes or their direct precursor compounds. The compound was published in 1998 by the Siemeling group and described at the time as diamagnetic. Structurally very similar representatives with penta-isopropylcyclopentadienyl- (⁵Cp) and 1,2,4-tri-tert-butylcyclopentadienyl ligands (Cp‘) have been ...
Dissertation
Die Synthese planar-chiraler 1,1´–Diaminoferrocenderivate
(2024)
Dieses Forschungsprojekt beschäftigt sich mit 1,1´-Diaminoferrocenderivaten, die aufgrund ei-nes weiteren Substituenten X in Nachbarstellung (ortho-Position) zu einer der Stickstoffgrup-pen planare Chiralität aufweisen. Obgleich 1,1´-Diaminoferrocen eine bewährte Schlüsselver-bindung innerhalb der Ferrocenchemie ist, insbesondere zur Darstellung von N,N-Chelatligan-den und N-heterozyklischen Tetrylenen, jeweils mit 1,1´-Ferrocenylenrückgrat, war der syn-thetische Zugang zu den hier behandelten planar-chiralen ...
Dissertation
City Development Regimes in-the-Making. Phronetic Analysis of Governance, Networks and Power in Cairo, 2011-2022
(2024)
Since the revolutionary uprising of January 2011, Cairo’s inner-city neighbourhoods have undergone rapid spatial transformations. Over the last decade, numerous old housing buildings have been replaced by modern ones, leading to the displacement of residents to the desert cities or newly-constructed neighbourhoods outside the city centre. The most remarkable transformations occurred since early 2018. Notably, these changes have been characterised by a fast implementation rate and a lack of community resistance to ...
Aufsatz
UVC Irradiation as a Surface Treatment of Polycarbonate to Generate Adhesion to Liquid Silicone Rubber in an Overmolding Process
(2024-04-18)
This study investigates the adhesion properties of polycarbonate (PC) and liquid silicone rubbers (LSR) through surface activation using ultraviolet C (UVC) radiation. While self-adhesive LSRs adhere easily to certain thermoplastic composites such as polybutylene terephthalate (PBT) and polyamides (PAs), bonding to PC typically requires surface treatment due to the lack of compatible functional groups. Previous methods like plasma or flame treatment have been effective, but the use of UVC radiation for surface ...
Dissertation
Existence and Asymptotic Behavior of Solutions to the Time-Periodic Navier-Stokes Equations in a Layer Domain with Nonhomogeneous Boundary Data
(2024)
This dissertation is dedicated to the analysis of the Navier-Stokes equations in a timeperiodic framework in the so-called layer domain Π = R2 × (0, 1), described by:
∂tu − νΔu + (u · ∇)u + ∇p = f in [0, T] × Π,
div u = 0 in [0, T] × Π,
u|∂Π = a for all t ∈ [0, T] ,
u|t=0 = u|t=T in Π.
The velocity field u and the pressure p are unknowns, while the external force f is prescribed. Challenges arise due to unboundedness of the layer Π and from introduction of a nonhomogeneous boundary condition a. The investigated ...
Dissertation
Promises and Pitfalls of Machine Learning Modeling in Psychological Research
(2024)
Algorithmen des maschinellen Lernens werden in der Psychologie und ihren Teildisziplinen immer beliebter. Sie werden häufig dafür angepriesen, dass sie mit der Multikollinearität von Prädiktorvariablen und komplexen Beziehungen zwischen Prädiktoren und Kriterien effizient umgehen können. Trotz ihrer Vorteile werden auch immer mehr kritische Stimmen laut, die auf die derzeitigen Grenzen von Vorhersagen durch maschinelles Lernen hinweisen und die Frage aufwerfen, ob die Algorithmen den Erwartungen gerecht werden. ...
Aufsatz
Land degradation and the upper hand of sustainable agricultural intensification in sub-Saharan Africa - A systematic review
(2024-05-13)
Sub-Saharan Africa (SSA) faces severe land degradation, driven by a combination of human and natural factors. Deforestation, inadequate land management practices, and unsustainable farming methods are the primary causes. The historical trends reveal the impact of soil erosion and nutrient depletion on 70% of the soil and 65% of its total land area. Unchecked degradation poses a critical threat to economic growth and poverty reduction initiatives. The region's food security is intricately linked to the complex interplay ...