Proposed Early Cambrian cephalopods are chimaeras, the oldest known cephalopods are 30 m.y. younger

Peer reviewe

Auf schwankendem Grund. Dekadenz und Tod im Venedig der Moderne

Anlass des Bandes ist das Centenarium von Thomas Manns Novelle "Der Tod in Venedig" (1912), in der Gustav von Aschenbach als ein der historischen Wissenschaft verpflichteter Schriftsteller in unsicheres Terrain jenseits rationaler Begrifflichkeit gerät, ins Sehnsuchtsland der Liebe und des Schönen, und schließlich in einen Grenzbereich, in dem alles Gestaltete ins Gestaltlose und schließlich in den Tod übergeht. Venedig um 1900, die auf Wasser gebaute, einstige Seerepublik in politischer Dekadenz ist nicht zufällig dafür topisch, und Aschenbach mit seinen ethischen, ästhetischen und epistemologischen Erschütterungen in Venedig nicht allein. Venedig prägte seine eigene Moderne aus und wurde als physisch erlebter wie imaginier­ter Ort für Dichter, Maler und Musiker zum Spiegel der Krisenerfahrungen um 1900. Anders gesagt: Die Stadt fungierte als Seismograph, mit dem sich der Verlust metaphysischer Gewissheiten, der Verlust des Vertrauens in die Evidenz des Wissens, in die Einheit der Person und der Zuverlässigkeit der Sprache aufzeichnen ließ. Die Unbestimmtheit, der Kontrollverlust, die der Lagu­nenstadt eigene Bewegung ›auf schwankendem Grund‹ wird bei Thomas Mann und seinen Zeitgenossen zum Motor der Kreativität

Recycling of poly(ethylene terephthalate) – a review focusing on chemical methods

Recycling of poly(ethylene terephthalate) (PET) is of crucial importance, since worldwide amounts of PETwaste increase rapidly due to its widespread applications. Hence, several methods have been developed, like energetic, material, thermo-mechanical and chemical recycling of PET. Most frequently, PET-waste is incinerated for energy recovery, used as additive in concrete composites or glycolysed to yield mixtures of monomers and undefined oligomers. While energetic and thermo-mechanical recycling entail downcycling of the material, chemical recycling requires considerable amounts of chemicals and demanding processing steps entailing toxic and ecological issues. This review provides a thorough survey of PET-recycling including energetic, material, thermo-mechanical and chemical methods. It focuses on chemical methods describing important reaction parameters and yields of obtained reaction products. While most methods yield monomers, only a few yield undefined low molecular weight oligomers for impaired applications (dispersants or plasticizers). Further, the present work presents an alternative chemical recycling method of PET in comparison to existing chemical methods

Vom PET-Abfall zur transparenten Hochleistungsfolie

Primäres Ziel und Aufgabe dieser Arbeit ist ... die Entwicklung einer neuen Recyclingmethode für PET, die die Nachteile der bisherigen Verwertungsmethoden vermeidet und unter weitgehendem Erhalt der bereits erbrachten Syntheseleistung definierte Oligomere liefert. Aus diesen können in Folge hochwertige Produkte hergestellt werden

Synthetische Dipeptidbausteine zur Stabilisierung der Struktur von Proteinen

Synthese eines Dipeptidbausteins auf der Basis von D-Ribose. Bestimmung der Eigenschaften als Turn-Mimetikum in verschiedenen Modellpeptiden. Verwendung des Mimetikums als integralen Bestandteil eines Proteins

Synthesis of ethylene terephthalate and ethylene naphthalate

Ethylene terephthalate and ethylene naphthalate oligomers of defined degree of polymerization were synthesized via chemical recycling of the parent polymers. The oligomers were used as defined building blocks for the preparation of novel block-co-polyesters having tailored sequence compositions. The sequence lengths were systematically varied using Design of Experiments. The dispersive surface energy and the specific desorption energy of the co-polymers were determined by inverse gas chromatography. The study shows that polyethylene terephthalate-polyethylene naphthalate (PET-PEN) block-co-polyesters of defined sequence lengths can be prepared. Furthermore, the specific and dispersive surface energies of the obtained block-co-polyesters showed a linear dependence on the oligomer molecular weight and it was possible to regulate and control their interfacial properties. In contrast, with the corresponding random-block-co-polyesters no such dependence was found. The synthesized block-co-polyesters could be used as polymeric modifying agents for stabilizing PET-PEN polymer blends

Improved thermostability and interfacial matching of nanoclay filler and ethylene vinyl alcohol matrix by silane-modification

The interfacial compatibility between polymers and nanoclay fillers as well as the thermostability of both components are important characteristics for processing them into polymer composites. While the polymer component is often grafted using common polymerization reactions, the nanoclay component is usually surface modified by surfactant treatment to improve compatibility. In the present study, the polymer ethylene vinyl alcohol and a nanoclay filler based on natural bentonite are both surface modified by different silanes, 3-glycidoxypropyltrimethoxysilane and methacryloxymethyltrimethoxysilane and their interfacial properties are investigated by inverse gas chromatography. The silane-modified samples had improved interfacial properties as reflected by a significant increase in dispersive and specific surface energies. Lewis acidities were determined using chloroform and 1,4-dioxane as polar probes and showed a good match between polymer and nanofiller interfaces. Lewis acidity was generally lower after silane-modification. Silanization yielded increased thermal stability of the treated samples. Thus, silanization led to improved compatibility and enhanced thermal stability which facilitates further processing