Synthese von Übergangsmetallkomplexen mit neuen Azolylpyridinliganden zur Heterogenisierung auf anorganischen Trägermaterialien

Die immer höheren Kosten für Energie und die Verknappung der natürlichen Ressourcen steigern die Bedeutung der Forschung an Katalysatoren für die chemische Synthese. Da die Herstellung geeigneter Katalysatoren zeitintensiv und teuer ist, sowohl durch den Einsatz von Edelmetallen als katalytisch aktivem Zentrum, als auch durch Verwendung von aufwändig synthetisierten Ligandsystemen, liegt der Fokus der Industrie auf heterogen katalysierten Verfahren. Im Arbeitskreis Thiel werden bereits seit längerer Zeit Pyrazolylpyridine als Chelatliganden für Übergangsmetallkomplexe synthetisiert, da sie leicht funktionalisierbar und damit in ihren elektronischen Eigenschaften modifizierbar sind. Ziel der vorliegenden Dissertation war die Synthese neuer Pyrazolyl- und Triazolylpyridine, die durch ihre funktionellen Gruppen eine einfache Heterogenisierung auf einem Trägermaterial ermöglichen, und so die Synthese von heterogenisierten Katalysatoren erlauben. Die Wahl fiel hierbei auf Ester- bzw. Chloridfunktionen, da die erfolgreiche Anbindung dieser Gruppen auf Trägermaterialien bereits bekannt ist. Die erfolgreiche Herstellung der an Position 5 des Azolylrings funktionalisierten Liganden gelang durch Synthese der Pyrazolylpyridine über eine Pyridylpyranonzwischenstufe bzw. durch Verwendung von Anhydriden als Edukte. In einem zweiten Schritt wurde das nächste Ziel, die Anbindung der hergestellten Liganden auf ein Trägermaterial, durch die Verwendung von Amin- und Imidazolfunktionalisierten Kieselgelen realisiert. Die erfolgreiche Synthese konnte durch Festkörper-NMR-Analytik bestätigt werden. Sowohl die freien, als auch die heterogenisierten Liganden wurden nun verwendet, um Übergangsmetallkomplexe zu synthetisieren. Es wurden Palladium(II)komplexe, ausgehend von Bis(benzonitril)palladium(II)dichlorid und Ruthenium(II)komplexe, ausgehend von Carbonylhydridotris(triphenylphosphan)ruthenium(II)chlorid, Tetrakis(dimethylsulfoxid)ruthenium(II)dichlorid und Dichlorido(\eta^{6} -para-cymol)ruthenium(II)dimer hergestellt und charakterisiert. Ebenfalls wurde die Eignung dieser Übergangsmetallkomplexe als Katalysatoren für chemische Reaktionen getestet. Die Palladiumkomplexe wurden in der Suzuki-Kupplung von Phenylhalogeniden mit Phenylboronsäure getestet. Die Eignung der Rutheniumverbindungen als Hydrierkatalysatoren wurde zum einen in der Hydrierung von CO2 zu Ameisensäure, zum anderen in der Transferhydrierung von Acetophenon untersucht. Dabei zeigte sich besonders eine gute Aktivität der Rutheniumkomplexe als Katalysatoren in der Transferhydrierung

Optimal design for dose finding studies on safety and efficacy

Magdeburg, Univ., Fak. für Mathematik, Diss., 2009von Katrin Rot

Visual Fixation Durations and Saccade Amplitudes: Shifting Relationship in a Variety of Conditions

Is there any relationship between visual fixation durations and saccade amplitudes in free exploration of pictures and scenes? In four experiments with naturalistic stimuli, we compared eye movements during early and late phases of scene perception. Influences of repeated presentation of similar stimuli (Experiment 1), object density (Experiment 2), emotional stimuli (Experiment 3) and mood induction (Experiment 4) were examined. The results demonstrate a systematic increase in the durations of fixations and a decrease for saccadic amplitudes over the time course of scene perception. This relationship was very stable across the variety of studied conditions. It can be interpreted in terms of a shifting balance of the two modes of visual information processing

Rethinking the Role of Scale for In-Context Learning: An Interpretability-based Case Study at 66 Billion Scale

Language models have been shown to perform better with an increase in scale on a wide variety of tasks via the in-context learning paradigm. In this paper, we investigate the hypothesis that the ability of a large language model to in-context learn-perform a task is not uniformly spread across all of its underlying components. Using a 66 billion parameter language model (OPT-66B) across a diverse set of 14 downstream tasks, we find this is indeed the case: $\sim$70% of attention heads and $\sim$20% of feed forward networks can be removed with minimal decline in task performance. We find substantial overlap in the set of attention heads (un)important for in-context learning across tasks and number of in-context examples. We also address our hypothesis through a task-agnostic lens, finding that a small set of attention heads in OPT-66B score highly on their ability to perform primitive induction operations associated with in-context learning, namely, prefix matching and copying. These induction heads overlap with task-specific important heads, reinforcing arguments by Olsson et al. (arXiv:2209.11895) regarding induction head generality to more sophisticated behaviors associated with in-context learning. Overall, our study provides several insights that indicate large language models may be under-trained for in-context learning and opens up questions on how to pre-train language models to more effectively perform in-context learning.Comment: Accepted at Annual Meeting of the Association for Computational Linguistics (ACL) 2023, Main Proceeding

MicroRNA-210 induces apoptosis in colorectal cancer via induction of reactive oxygen

Additional file 2: Figure S2. Representative flow cytometric histograms of CRC cell lines 72 h post transfection with pre-miR-210 and a control miRNA, respectively. Cells were stained with by PI staining and subjected to FACS analysis

Development and initial evaluation of a point-of-care educational app on medical topics in orthogeriatrics

INTRODUCTION: Research by AOTrauma's orthogeriatrics education taskforce identified ongoing educational needs for surgeons and trainees worldwide regarding the medical management of older adults with a fracture. To address practicing surgeons' preference for increased use of mobile learning, a point-of-care educational app was planned by a committee of experienced faculty. The goals were to deliver the app to surgeons, trainees, and other healthcare professionals, to measure usage, and to evaluate the impact on patient care. MATERIALS AND METHODS: The committee of geriatricians and surgeons designed and developed four modules on osteoporosis, delirium, anticoagulation, and pain based on published evidence and the content was programmed into mobile app formats. A registration form was integrated and a 14-question online evaluation survey was administered to users. RESULTS: The AOTrauma Orthogeriatrics app was installed by 17,839 users worldwide between September 2014 and October 2015: Android smartphones (44%), iPhones (32%), iPads (15%), Android tablets (9%). 920 users registered and 100 completed the online evaluation: orthopedic/trauma surgeons (67%), residents/fellows (20%), and other professionals (13%). Ratings for all aspects were 4 or higher on a 1-5 Likert scale (5 = Excellent). 80% of evaluation respondents found the answer to their question or educational need on their last visit, and 26 of 55 respondents (47%) reported making a change in an aspect of their management of patients as a result of their learning from the app. CONCLUSION: The orthogeriatrics app reached its intended audiences and was rated highly as a method of providing education to help improve patient care. Content input by experienced faculty and app improvements based on user feedback were key contributors to successful implementation

Manufacturing of embedded multimode waveguides by reactive lamination of cyclic olefin polymer and polymethylmethacrylate

We demonstrate the manufacturing of embedded multimode optical waveguides through linking of polymethylmethacrylate (PMMA) foils and cyclic olefin polymer (COP) filaments based on a lamination process. Since the two polymeric materials cannot be fused together through interdiffusion of polymer chains, we utilize a reactive lamination agent based on PMMA copolymers containing photoreactive 2-acryloyloxyanthraquinone units, which allows the creation of monolithic PMMA-COP substrates through C-H insertion reactions across the interface between the two materials. We elucidate the lamination process and evaluate the chemical link between filament and foils by carrying out extraction tests with a custom-built tensile testing machine. We also show attenuation measurements of the manufactured waveguides for different manufacturing parameters. The lamination process is in particular suited for large-scale and low-cost fabrication of board-level devices with optical waveguides or other micro-optical structures, e.g., optofluidic devices. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).DFG/SFB/TRR 12