Gutenberg Open Science (Univ. Mainz)
Not a member yet
11784 research outputs found
Sort by
Electrochemical incorporation of sulfur dioxide towards value-added products
Get PDFAs part of the BMBF future cluster ETOS (Electrifying Technical Organic Syntheses), this dissertation explored the development, optimization, and application of novel electrochemical multi-component sulfonylation reactions utilizing abundant and broadly applicable starting materials. Stock solutions of sulfur dioxide were used as an efficient and convenient way to incorporate the toxic pollutant SO₂ into value-added products. The electrophilic nature of SO₂ enables its formal insertion into O–H bonds of alcohols, forming monoalkylsulfites in-situ with the assistance of an organic base. The nucleophilic properties of these intermediates were then harnessed to engage with anodically oxidized substrates, facilitating the formation of new C–S bonds.
The methodology was first applied to styrene derivatives, enabling direct electrosulfonylation to afford β-styrenesulfonates. A similar transformation was achieved using cinnamic acids as a biogenic feedstock through a decarboxylative sulfonylation pathway. Furthermore, the scope of the reaction was extended to non-aromatic substrates by employing readily oxidizable tertiary amines as precursors for enamines, resulting in the formation of enaminylsulfonates.
These advancements significantly expanded the applicability of electrochemical sulfonylation reactions, overcoming previous limitations such as the necessity for prefunctionalization, the use of surrogate reagents, toxic solvents, or complex electrochemical setups, while at the same time broadening the substrate scope of electrochemical sulfonylation reactionsIm Rahmen des BMBF-Zukunftsclusters ETOS (Elektrifizierung Technischer Organischer Synthese) wurde in dieser Dissertation die Entwicklung, Optimierung und Anwendung neuartiger elektrochemischer Mehrkomponenten-Sulfonylierungsreaktionen unter Verwendung leicht zugänglicher und breit einsetzbarer Ausgangsmaterialien untersucht. Stammlösungen von Schwefeldioxid wurden als effiziente und praktische Möglichkeit genutzt, den giftigen Schadstoff SO₂ in höherwertige Produkte einzubauen. Die elektrophile Natur von SO₂ ermöglicht seine formale Inkorporation in O–H-Bindungen von Alkoholen, wobei mit Hilfe einer organischen Base Monoalkylsulfite in situ gebildet werden. Die nucleophilen Eigenschaften dieser Zwischenprodukte wurden anschließend genutzt, um zuvor anodisch oxidierte Substrate anzugreifen und die Bildung neuer C–S-Bindungen zu ermöglichen.
Die Methodik wurde zunächst auf Styrolderivate angewendet, wodurch eine direkte elektrochemische Sulfonylierung zur Herstellung von β-Styrolsulfonsäureerstern ermöglicht wurde. Eine ähnliche Transformation wurde mit Zimtsäuren als biogenen Ausgangsmaterialien mittels decarboxylierender Sulfonylierung erreicht. Darüber hinaus wurde der Anwendungsbereich der Reaktion auf nicht-aromatische Substrate erweitert, indem leicht oxidierbare, tertiäre Amine als Vorläufer für Enamine verwendet wurden, was zur Bildung von Enaminylsulfonaten führte.
Diese Fortschritte haben die Anwendungsbreite von elektrochemischen Sulfonylierungsreaktionen erweitert und den Substratscope erheblich vergrößert. Darüber hinaus konnten frühere Einschränkungen wie die Notwendigkeit von Vorfunktionalisierungen, die Verwendung von Surrogaten, toxischen Lösungsmitteln oder komplexen elektrochemischen Aufbauten überwunden werden.XII, 310 Seiten ; Illustrationen, Diagramm
User-friendly truncated wigner approximation for dissipative spin dynamics
Get PDFWe put forward a user-friendly framework of the truncated Wigner approximation (TWA) for dissipative quantum many-body systems. Our approach is computationally affordable and it features a straightforward implementation. The leverage of the method can be ultimately traced to an intimate connection between the TWA and the semiclassical limit of the quantum Langevin equation, which we unveil by resorting to a path-integral representation of the Lindbladian. Our approach allows us to explore dynamics from early to late times in a variety of models at the core of modern atomic, molecular, and optical research, including lasing, central-spin models, driven arrays of Rydbergs, and correlated emission in free space. Notably, our TWA approach outperforms the cumulant-expansion method in certain models and performs comparably well in others, all while offering significantly lower computational costs and a much simpler formulation of the dynamical equations. We therefore argue that TWA could, in the near future, become a primary tool for a fast and efficient first exploration of driven-dissipative many-body dynamics on consumer-grade computers
Schluckstörungen bei akutgeriatrischen Patienten: Eine retrospektive Studie zur Detektion von Schluckstörungen und Symptomwahrnehmung durch Patienten und Angehörige.
Get PDFIII, 79 Seiten ; Illustrationen, Diagramm
Retrospective multicenter analysis of the Trenza Embolization Device for endovascular therapy of intracranial aneurysms : initial results and short-term follow-up
Get PDFBackground Intrasaccular devices are increasingly used in endovascular therapy of intracranial aneurysms, in particular wide-necked and ruptured aneurysms. The Trenza Embolization Device (TED) is an innovative intrasaccular device for medium- to large-sized aneurysms. Currently, literature about the TED is scarce.
Methods In eight participating European centers, 25 aneurysms (3 ruptured) in 25 patients (18 females, mean age 62.4 years) treated with the TED outside the currently recruiting prospective, post-market, multicenter study were included in this retrospective, multicenter analysis. Primary endpoints for clinical safety were the absence of stroke and death. Primary endpoint for technical success was implantation of TED without necessity of adjunct stenting. Primary and secondary endpoints for efficacy were adequate angiographic occlusion according to the Modified Raymond–Roy Classification (MRRC) immediately after the procedure and at first follow-up (FU).
Results Stent-assistance was required in two cases. Thus primary endpoint for technical success was reached in 23/25 (92%) cases. With one symptomatic thrombotic event, primary safety endpoint was reached in 24/25 (96%) cases. At the end of the procedure, complete occlusion (MRRC I) was achieved in 12/25 (48%), and a small residual neck (MRRC II) remained in 13/25 (52%) cases. In 19 cases FU (mean 6 months) was available, showing adequate occlusion in 17/19 (89.5%) cases (MRRC I in 8/19 and stable MRRC II in 9/19 cases) and relevant reperfusion MRRC IIIa with indication to retreatment in 2/19 (10.5%) cases.
Conclusions The results of this first retrospective, multicenter experience with the TED appear promising. Further prospective, multicenter studies with larger patient cohorts, as well as long-term FU, are required
Climate and environmental reconstruction of the last 16,000 years in central-eastern Brazil using a speleothem multiproxy approach
Get PDFPaleoclimate archives, such as speleothems, provide critical understanding of past climate
variability. Speleothems are particularly valuable as a continental archive since they occur worldwide,
can be precisely dated via the ²³⁰Th-U dating method and form by the precipitation of calcium
carbonate from percolating drip water within caves, integrating signals from soil, bedrock, and
rainfall. In general, oxygen (δ¹⁸O) and carbon (δ¹³C) isotope ratios have been the most used proxies
in speleothem-based studies, serving as indicators of past hydroclimate and environmental changes.
More recently, multi-proxy approach studies have been growing, since they provide more
comprehensive understanding of the complex processes that influence speleothem formation and
climate signal interpretation.
In South America, speleothem studies have greatly advanced our understanding of the
South American Summer Monsoon (SASM), the continent's dominant climate system that leads
precipitation over tropical South America. The SASM has a NW-SE convection band that extends
over the continent, the South Atlantic Convergence Zone (SACZ). This thesis applies a multi-proxy
approach to reconstruct the hydrological, environmental and temperature evolution of the last
16,000 years from central-eastern Brazil based on a stalagmite collected in São Mateus Cave, Goiás
State. The cave lies in a transitional climate zone between humid tropical and semi-arid regions,
making it highly sensitive to changes in the SASM and SACZ.
The results revealed that central-east Brazil is largely influenced by both tropical and highlatitude
forcings, such as changes in solar radiation, ocean–atmosphere dynamics, and
interhemispheric temperature gradients in several time-scales. During the deglacial period, rapid
temperature and hydrological changes occurred concomitant with abrupt climate shifts in the
Northen Hemisphere. During the Holocene, the earlier period evidences shifting climate and
environmental conditions, likely due to the low insolation. The middle and late Holocene present
more stable conditions responding to the increasing insolation, which is the dominant forcing at
these periods. Finally, the multi-proxy results show pronounced hydrological, environmental and
temperature changes during the during the deglaciation and the Holocene. The São Mateus record
provides new evidence of how SACZ and SASM developed over the last 16,000 years.XV, 132 Seiten ; Illustrationen, Diagramm
Microphysical parameter choices modulate ice content and relative humidity in the outflow of a warm conveyor belt
Get PDFWarm conveyor belts (WCBs) play a crucial role in Earth's climate by transporting water vapor and hydrometeors into the upper troposphere/lower stratosphere (UTLS), where they influence radiative forcing. However, a major source of uncertainty in numerical weather prediction (NWP) models and climate projections stems from the parameterization of microphysical processes and their impact on cloud radiative properties as well as the vertical re-distribution of water. In this study, we use Lagrangian data from a perturbed parameter ensemble (PPE) of a WCB case study to investigate how variations in microphysical parameterizations influence water transport into the UTLS and the outflow cirrus properties. We find that the thermodynamic conditions (pressure, temperature, specific humidity) at the end of the WCB ascent show little sensitivity to the explored parameter perturbations. In contrast, ice content and relative humidity exhibit substantial variability, primarily driven by the capacitance of ice (CAP) and the scaling of ice formation processes directly influenced by ice-nucleating particle (INP) concentrations. Different combinations of CAP and INP scaling yield vastly different ice and relative humidity distributions at the end of the ascent and in the subsequent hours. These differences are particularly pronounced in fast-ascending air parcels, where modifications to the saturation adjustment scheme (SAT) introduce small variations in pressure and temperature at the end of ascent. Our findings have potential implications for parameter choices in cloud models and considerations for geoengineering strategies. Future comparisons with high-quality observational data could help constrain the most realistic parameter choices, ultimately improving weather and climate forecasts
Verwendung eines Auflichtmikroskops zur Diagnostik von malignen Hautveränderungen
Get PDF40 Seiten ; Illustrationen, Diagramm
Untersuchung zur Ausprägung der Migräne-Episoden und der Beeinflussbarkeit durch die repetitive transkranielle Magnetstimulation
Get PDFca. 100 Seite
Correlating on-the-fly electrical and optical skyrmion readout
No full textMagnetic skyrmions, topologically stabilized spin textures, are promising candidates for future memory devices and non-conventional computing applications due to their enhanced stability, nonlinear interactions, and low-power manipulation capabilities. Despite their significant potential, the reliable electrical readout of individual skyrmions remains a fundamental challenge. While magnetic tunnel junctions and anomalous Hall effect (AHE)-based techniques have demonstrated skyrmion detection capabilities, they currently fail to reliably detect single, moving skyrmions, as required for applications. Our approach leverages thermally activated skyrmions, where a low constant drive current simultaneously generates both skyrmion motion and the Hall voltage necessary for detection. We demonstrate the reliability of this method through real-time correlations between measured Hall voltage signals and direct Kerr microscopy imaging. Two consecutive Hall crosses allow for determining the skyrmion velocity, in accordance with Kerr microscopy videos. We present an analytical formula for the skyrmion AHE readout signal, demonstrating scalability from micrometer- to nanometer-sized skyrmions. These advances establish a robust platform for skyrmion-based sensors, counters, and unconventional computing systems that depend on precise individual skyrmion control and detection
Die ältere Patientin im Fokus der Senologie
No full textBrustkrebs ist die häufigste Krebserkrankung der Frau, und 40 % der betroffenen Frauen erkranken nach dem 70. Lebensjahr in Deutschland. Trotz des zunehmenden Fokus auf die ältere Patientin ist diese in den Studien unterrepräsentiert. Das funktionelle Alter und eine mögliche Fragilität, nicht das chronologische Alter, sollten die Therapieentscheidung beeinflussen. Ein geriatrisches Assessment (cGA) oder ein „pre-screening“ vor einem cGA sollten spätestens ab dem 75. Lebensjahr standardmäßig erfolgen. Um das Gesamtüberleben einschätzen zu können, werden Kalkulatoren, beispielsweise ePrognosis, verwendet. Zudem können Chemotherapietoxizität-Kalkulatoren, etwa CARG oder CRASH, für ältere onkologische Patientinnen genutzt werden. Es sollte eine Übertherapie, aber auch eine Untertherapie der fitten älteren Patientin vermieden werden. Das Ziel ist eine personalisierte Versorgung, welche die Vorteile der Behandlung gegen die Risiken der Toxizität und die Auswirkungen auf die Lebensqualität abwägt und gleichzeitig den Gesundheitszustand und die Präferenzen der Patientin berücksichtigt