Solvent- and time-dependent fluorescence of photoacids based on pyranine

The process of excited-state proton transfer (ESPT) is frequently found in aromatic alcohols. Upon electronic excitation, the acidity of these molecules increases by 5-10 orders of magnitude. While being in the excited state, the proton can be transferred to a suitable acceptor unit due to the high photoacidity. In this thesis, the ESPT behavior of five new photoacids in different solvents as proton acceptor is investigated. The new molecules are based on the well-known pyranine photoacid, with electronic transitions in the visible part of the electromagnetic spectrum. Steady-state and time-resolved spectroscopy is used to characterize the new molecules and prove them as “super”-photoacids, which are capable of ESPT in organic solvents. The combination of steady-state measurements with a solvatochromic analysis showed that it is an intramolecular charge transfer on the photoacid side, which correlates best with the photoacidity of the molecule. The proton transfer rate constants could be measured by using time-resolved methods with picosecond time resolution. The experimental rate constants of the molecules in the solvents water, methanol and ethanol could be correlated by empirical Marcus-like free energy correlations. The decreased proton transfer efficiency in alcohols compared to water is mainly due to equilibrium solvation energies.Protonentransfer aus dem angeregten elektronischen Zustand ist ein Phänomen, das bei den meisten aromatischen Alkoholen zu beobachten ist. Die Azidität dieser Moleküle nimmt durch Absorption eines UV-Vis-Photons um 5-10 Größenordnungen zu. Aufgrund dieser hohen Photoazidität wird das azide Proton während der Lebensdauer des angeregten Zustandes auf einen geeigneten Protonenakzeptor übertragen. In dieser Arbeit werden fünf neue Photosäuren hinsichtlich ihrer ESPT-Fähigkeit in verschiedenen Lösemitteln getestet. Diese Moleküle, die ausgehend von dem gut untersuchten HPTS Molekül hergestellt wurden, absorbieren und emittieren im sichtbaren Wellenlängenbereich. Ihre Charakterisierung mittels stationärer und zeitaufgelöster Spektroskopie zeigte, dass sie den sogenannten „Super“-Photosäuren zuzuordnen sind, die auch organische Lösemittel protonieren. Durch die Kombination von stationärer Spektroskopie mit einer solvatochromen Analyse konnte gezeigt werden, dass die Stärke eines internen Ladungstransfers vor dem Protonentransferschritt proportional zur Photoazidität ist. Die Ratenkonstanten des Protonentransfers wurden mittels zeitaufgelöster Methoden mit Pikosekundenauflösung bestimmt. Diese in Wasser, Methanol und Ethanol gefundenen Ratenkonstanten können durch Freie-Energie Beziehungen basierend auf der Marcus Theorie beschrieben werden. Die geringere Transfereffizienz in Alkoholen konnte auf kleinere Gleichgewichts-Lösemittelenthalpie zurückgeführt werden

3-D Printed Protective Equipment during COVID-19 Pandemic

While the number of coronavirus cases from 2019 continues to grow, hospitals are reporting shortages of personal protective equipment (PPE) for frontline healthcare workers. Furthermore, PPE for the eyes and mouth, such as face shields, allow for additional protection when working with aerosols. 3-D printing enables the easy and rapid production of lightweight plastic frameworks based on open-source data. The practicality and clinical suitability of four face shields printed using a fused deposition modeling printer were examined. The weight, printing time, and required tools for assembly were evaluated. To assess the clinical suitability, each face shield was worn for one hour by 10 clinicians and rated using a visual analogue scale. The filament weight (21-42 g) and printing time (1:40-3:17 h) differed significantly between the four frames. Likewise, the fit, wearing comfort, space for additional PPE, and protection varied between the designs. For clinical suitability, a chosen design should allow sufficient space for goggles and N95 respirators as well as maximum coverage of the facial area. Consequently, two datasets are recommended. For the final selection of the ideal dataset to be used for printing, scalability and economic efficiency need to be carefully balanced with an acceptable degree of protection

The LAILAPS Search Engine: A Feature Model for Relevance Ranking in Life Science Databases

Efficient and effective information retrieval in life sciences is one of the most pressing challenge in bioinformatics. The incredible growth of life science databases to a vast network of interconnected information systems is to the same extent a big challenge and a great chance for life science research. The knowledge found in the Web, in particular in life-science databases, are a valuable major resource. In order to bring it to the scientist desktop, it is essential to have well performing search engines. Thereby, not the response time nor the number of results is important. The most crucial factor for millions of query results is the relevance ranking. In this paper, we present a feature model for relevance ranking in life science databases and its implementation in the LAILAPS search engine. Motivated by the observation of user behavior during their inspection of search engine result, we condensed a set of 9 relevance discriminating features. These features are intuitively used by scientists, who briefly screen database entries for potential relevance. The features are both sufficient to estimate the potential relevance, and efficiently quantifiable. The derivation of a relevance prediction function that computes the relevance from this features constitutes a regression problem. To solve this problem, we used artificial neural networks that have been trained with a reference set of relevant database entries for 19 protein queries. Supporting a flexible text index and a simple data import format, this concepts are implemented in the LAILAPS search engine. It can easily be used both as search engine for comprehensive integrated life science databases and for small in-house project databases. LAILAPS is publicly available for SWISSPROT data at http://lailaps.ipk-gatersleben.d

High-sensitivity cardiac Troponin T delta concentration after repeat pulmonary vein isolation

Introduction: Difference between high-sensitivity cardiac troponin T concentrations (hs-cTnT) before and after ablation procedure (delta concentration) reflects the amount of myocardial injury. The aim of the study was to investigate hs-cTnT prognostic power for predicting atrial fibrillation (AF) recurrence after repeat pulmonary vein isolation (PVI) procedure. Materials and methods: Consecutive patients with paroxysmal AF undergoing repeat PVI using a focal radiofrequency catheter were included in the study. Hs-cTnT was measured before and 18-24 hours after the procedure. Standardized 3, 6 and 12-month follow-up was performed. Cox-regression analysis was used to identify predictors of AF recurrence. Results: A total of 105 patients undergoing repeat PVI were analysed (24% female, median age 61 years). Median (interquartile range) hs-cTnT delta after repeat PVI was 283 (127 - 489) ng/L. After a median follow-up of 12 months, AF recurred in 24 (23%) patients. A weak linear relationship between the total radiofrequency energy delivery time and delta hs-cTnT was observed (Pearson R2 = 0.31, P = 0.030). Delta Hs-cTnT was not identified as a significant long-term predictor of AF recurrence after repeated PVI (P = 0.920). Conclusion: This was the first study evaluating the prognostic power of delta hs-cTnT in predicting AF recurrence after repeat PVI. Delta hs-cTnT does not predict AF recurrence after repeat PVI procedures. Systematic measurement of hs-cTnT after repeat PVI does not add information relevant to outcome