A finite strain thermo-mechanically coupled material model for semi-crystalline polymers

In this work, a thermo-mechanically coupled constitutive model for semicrystalline polymers is derived in a thermodynamically consistent manner. In general, the macroscopic material behaviour of this class of materials is dictated by the underlying microstructure, i.e. by the distribution and structure of crystalline regimes, which form up after cooling from the amorphous melt. In order to account for the latter, the total degree of crystallinity is incorporated as an internal variable and its evolution is prescribed by means of a non-isothermal crystallisation kinetics model. The numerically efficient and robust framework is characterised based on experimental data for Polyamide 6 and shows a promising potential to predict the hyperelastic, visco-plastic material behaviour at various temperature

A finite strain thermo-mechanically coupled material model for semi-crystalline polymers

In this work, a thermo-mechanically coupled constitutive model for semicrystalline polymers is derived in a thermodynamically consistent manner. In general, the macroscopic material behaviour of this class of materials is dictated by the underlying microstructure, i.e. by the distribution and structure of crystalline regimes, which form up after cooling from the amorphous melt. In order to account for the latter, the total degree of crystallinity is incorporated as an internal variable and its evolution is prescribed by means of a non-isothermal crystallisation kinetics model. The numerically efficient and robust framework is characterised based on experimental data for Polyamide 6 and shows a promising potential to predict the hyperelastic, visco-plastic material behaviour at various temperature

pH-Schaltbare Rotaxane für den lichtgetriebenen Protonentransport

Im Rahmen des Sonderforschungsbereiches 677 „Funktion durch Schalten“ soll eine lichtgetriebene Protonenpumpe auf Basis eines Rotaxans entwickelt werden. Diese soll, eingebaut in eine Membran, Protonen gegen einen Konzentrationsgradienten durch die Membran transportieren können. Das Rotaxan setzt sich aus einem protonierbaren Makrozyklus und einer Achse mit einer permanent positiven Ladung neben einer Amidfunktion, als Bindestelle für den Makrozyklus, zusammen. Aufgrund repulsiver Wechselwirkungen bewegt sich der protonierte Makrozyklus auf die andere Seite der Achse. In dieser Arbeit wurden Rotaxane mittels trapping-Verfahren hergestellt. Dafür wurden entsprechende Alkin- und Azidhalbachsen mit einem Makrozyklus in einer Kupfer(I)-katalysierten 1,3-dipolaren Cycloaddition zu den Rotaxanen 43 und 52 umgesetzt. Durch den Einbau einer Verlängerungseinheit konnte sowohl die Ausbeute der Rotaxansynthese verbessert als auch die Länge des Rotaxans auf die Dimension einer Membran (3 − 4 nm) angepasst werden. Die Schaltbarkeit der Rotaxane konnte durch pH-Experimente mittels NMR-Spektroskopie nach¬gewiesen werden. Durch Säure- und Basenzugabe konnte der Makrozyklus reversibel zwischen der Amidbindestelle und der Triazol¬einheit hin und her geschaltet werden. Als Antrieb für ein lichtgetriebenes Rotaxan ist die Verwendung einer Photosäure, wie ein 2,4-Dinitrobenzylpyridin-Derivat (DNBP), vorgesehen. Durch NMR-Experimente konnte jedoch gezeigt werden, dass die Acidität der Photosäure nicht ausreicht, um den Pyridinmakrozyklus zu protonieren. Um das Rotaxan in eine Membran einbauen zu können, ist die Funktionalisierung der Stopper mit hydrophilen Gruppen notwendig. Dafür konnte eine neue Azidhalbachse mit einer geschützten Sulfonsäurefunktion hergestellt und zum Rotaxan 85 umgesetzt werden. Durch die anschließende Entschützung konnte ein amphiphiles Rotaxan 88 mit einer freien Sulfonsäureeinheit erhalten werden

Influence of transcrystalline layer on finite element mesoscale modeling of polyamide 6 based single polymer laminate composites

This study presents a novel approach for finite element modeling of the elastic behavior of a plain-woven reinforced single polymer laminate composites (WSPC) based on polyamide 6 (PA6). These composites are produced via compression molding of PA6 woven textile structures that are powder-coated by anionic PA6 microparticles. Morphological and structural analysis complemented by electron microscopy, image processing and X-ray diffraction suggest the presence of transcrystalline layer (TCL) at the matrix-reinforcement interface. Having in mid this experimental fact, a novel procedure is developed for finite level discretization of TCL in the representative volume element (RVE) during tensile straining. The procedure correlates the material properties with the overall load applied, thus adequately modelling the tensile behavior of the WSPC based on the constituent materials. The stress field along the elements of the RVE model is studied while the tensile loads were applied in two principal directions. A good agreement between the real mechanical behavior and that calculated based on the model was demonstrated.IPC and 2C2T gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. The authors affiliated to 2C2T acknowledge also partial funding from FCT - Fundação para a Ciência e a Tecnologia within the projects POCI- 01-0145-FEDER-007136 and UID/CTM/00264. S.D. Tohidi thanks to FCT for the PhD Grant SFRH/BD/94759/2013. N. Dourado acknowledges FCT for the financial support through the projects UID/EEA/04436/2013 and POCI-01-0145-FEDER-006941. M. Rezazadeh acknowledges the support provided by FEDER and FCT funds through project POCI-01-0145-FEDER-029485. N.Q. Quyền thanks for the financial support of FCT through the project PESTUID/CTM/00264. A. Zille also acknowledges the FCT Investigator Research contract IF/00071/2015. S. Hesseler and T. Gries gratefully acknowledge the financial support of German Science Foundation (DFG) through the project RE1057/41. Z. Z. Denchev and N. V. Dencheva acknowledge the support by National Funds through FCT, project UID/CTM/50025/2019. N. Dencheva is also grateful for the financial support of FCT in the frames of the strategic project UID/CTM/50025/2013 and the personal program-contract CTTI-51/18-IP

Biochemical and structural characterisation of a haloalkane dehalogenase from a marine Rhodobacteraceae

types: Journal Article; Research Support, Non-U.S. Gov'tCopyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. NOTICE: This is the author’s version of a work accepted for publication by Elsevier. Changes resulting from the publishing process, including peer review, editing, corrections, structural formatting and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in FEBS Letters Vol. 588, Issue 9, pp. 1616 – 1622 DOI: 10.1016/j.febslet.2014.02.056A putative haloalkane dehalogenase has been identified in a marine Rhodobacteraceae and subsequently cloned and over-expressed in Escherichia coli. The enzyme has highest activity towards the substrates 1,6-dichlorohexane, 1-bromooctane, 1,3-dibromopropane and 1-bromohexane. The crystal structures of the enzyme in the native and product bound forms reveal a large hydrophobic active site cavity. A deeper substrate binding pocket defines the enzyme preference towards substrates with longer carbon chains. Arg136 at the bottom of the substrate pocket is positioned to bind the distal halogen group of extended di-halogenated substrates.Wellcome TrustEPSRCHRMUniversity of ExeterBBSR

3D Hydrogels Containing Interconnected Microchannels of Subcellular Size for Capturing Human Pathogenic Acanthamoeba Castellanii

3D Hydrogels Containing Interconnected Microchannels of Subcellular Size for Capturing Human Pathogenic Acanthamoeba Castellani

Innovation und Qualifikation berufliche Bildung und neue Techniken im Unternehmen. Fachtagung am 23. und 24. Oktober 1986 im Wissenschaftszentrum in Bonn

IAB-93-3120-50 AN 086,0 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman