Report of the Committee on Meteorology and Epidemics for the Year 1880, in Philadelphia

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Bifunktionale Organokatalysatoren für die kinetische Racemattrennung von Azlactonen und Oxazinonen

Die vorliegende Arbeit beschreibt die Entwicklung organokatalytischer Verfahren zur Synthese von enantiomerenreinen alpha- und beta-Aminosäuren. Unter Verwendung von bifunktionalen Katalysatoren auf (Thio-)Harnstoffbasis gelang die alkoholytische dynamisch-kinetische Racemattrennung (DKR) von Azlactonen, wobei die gebildeten N-Acyl-alpha-aminosäureester in Enantiomerenüberschüssen von bis zu 95 % erhalten wurden. Dies sind die besten Ergebnisse, die bislang in der chemokatalytischen DKR von Azlactonen erzielt wurden. Des Weiteren gelang es, durch eine Kombination aus spektroskopischen Untersuchungen und kinetischen Experimenten ein vollständiges mechanistisches Bild der Reaktion zu erstellen. Nachfolgend wurden die bifunktionalen Organokatalysatoren in der asymmetrischen, alkoholytischen Ringöffnung von Oxazinonen eingesetzt. Bei dieser neuartigen Transformation gelang es, eine Reihe von unterschiedlich substituierten, racemischen Oxazinonen durch kinetische Racematspaltung (KR) in wertvolle, hoch enantiomerenangereicherte N-Acyl-beta-aminosäureester umzusetzen. Dabei war es stets möglich, das Oxazinon in > 97 % ee zu erhalten

Augmentation of implant surfaces with BMP-2 in a revision setting:effects of local and systemic bisphosphonate

AIMS: We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants. METHODS: An established allografted revision protocol was implemented bilaterally into the stifle joints of 24 canines. At revision surgery, each animal received one BMP-2 (5 µg) functionalized implant, and one raw implant. One group (12 animals) received bone graft impregnated with zoledronate (0.005 mg/ml) before impaction. The other group (12 animals) received untreated bone graft and systemic zoledronate (0.1 mg/kg) ten and 20 days after revision surgery. Animals were observed for an additional four weeks before euthanasia. RESULTS: No difference was detected on mechanical implant fixation (load to failure, stiffness, energy) between local or systemic zoledronate. Addition of BMP-2 had no effect on implant fixation. In the histomorphometric evaluation, implants with local zoledronate had more area of new bone on the implant surface (53%, p = 0.025) and higher volume of allograft (65%, p = 0.007), whereas implants in animals with systemic zoledronate had the highest volume of new bone (34%, p = 0.003). Systemic zoledronate with BMP-2 decreased volume of allograft by 47% (p = 0.017). CONCLUSION: Local and systemic zoledronate treatment protects bone at different stages of maturity; local zoledronate protects the allograft from resorption and systemic zoledronate protects newly formed bone from resorption. BMP-2 in the dose evaluated with experimental revision implants was not beneficial, since it significantly increased allograft resorption without a significant compensating anabolic effect. Cite this article: Bone Joint Res 2021;10(8):488–497

Catalyst Development for High-Temperature Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) Applications

A constant increase in global emission standard is causing fuel cell (FC) technology to gain importance. Over the last two decades, a great deal of research has been focused on developing more active catalysts to boost the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC), as well as their durability. Due to material degradation at high-temperature conditions, catalyst design becomes challenging. Two main approaches are suggested: (i) alloying platinum (Pt) with low-cost transition metals to reduce Pt usage, and (ii) developing novel catalyst support that anchor metal particles more efficiently while inhibiting corrosion phenomena. In this comprehensive review, the most recent platinum group metal (PGM) and platinum group metal free (PGM-free) catalyst development is detailed, as well as the development of alternative carbon (C) supports for HT-PEMFCsThis work was financially supported by the Innovation Fund Denmark (MAKE-FC-LAST, 2079-00005B) and the Energy Technology Development and Demonstration (EUDP) Program (COBRA-Drive and 64018-0118). The authors gratefully acknowledge financial support from the Spanish MINECO through the Project PID2020- 116490GB-I00. The authors also thank financial support from the Comunidad de Madrid and the Spanish State through the Recovery, Transformation, and Resilience Plan [“Materiales Disruptivos Bidimensionales (2D)” (MAD2D-CM) (UAM1)-MRR Materiales Avanzados], and the European Union through the Next Generation EU funds. IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, grant SEV2016-0686