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Weinberger F.,University Pierre and Marie Curie | Weinberger F.,CNRS Integrative Biology of Marine Models | Weinberger F.,Leibniz Institute of Marine Science | Guillemin M.-L.,Austral University of Chile | And 13 more authors.
Journal of Phycology | Year: 2010

Combined phylogenetic, physiological, and biochemical approaches revealed that differences in defense-related responses among 17 species belonging to the Gracilariaceae were consistent with their evolutionary history. An oxidative burst response resulting from activation of NADPH oxidase was always observed in two of the subgenera of Gracilaria sensu lato (Gracilaria, Hydropuntia), but not in Gracilariopsis and in species related to Gracilaria chilensis (" chilensis" clade). On the other hand, all species examined except Gracilaria tenuistipitata var. liui and Gracilariopsis longissima responded with up-regulation of agar oligosaccharide oxidase to an challenge with agar oligosaccharides. As indicated by pharmacological experiments conducted with Gracilaria chilensis and Gracilaria sp. " dura," the up-regulation of agar oligosaccharide oxidase involved an NAD(P)H-dependent signaling pathway, but not kinase activity. By contrast, the activation of NADPH oxidase requires protein phosphorylation. Both responses are therefore independent, and the agar oligosaccharide-activated oxidative burst evolved after the capacity to oxidize agar oligosaccharide, probably providing additional defensive capacity to the most recently differentiated clades of Gracilariaceae. As demonstrated with Gracilaria gracilis, Gracilaria dura, and Gracilariopsis longissima, the different responses to agar oligosaccharides allow for a fast and nondestructive distinction among different clades of gracilarioids that are morphologically convergent. Based upon sequences of the chloroplast-encoded rbcL gene, this study suggests that at least some of the samples from NW America recorded as Gs. lemanaeiformis are probably Gs. chorda. Moreover, previous records of Gracilaria conferta from Israel are shown to be based upon misidentification of Gracilaria sp. " dura," a species that belongs to the Hydropuntia subgenus. © 2010 Phycological Society of America.


Becker T.,Max Planck Institute for Chemical Ecology | Gorls H.,Institute for Inorganic and Analytical Chemistry | Pauls G.,Max Planck Institute for Chemical Ecology | Wedekind R.,Max Planck Institute for Chemical Ecology | And 3 more authors.
Journal of Organic Chemistry | Year: 2013

A novel synthetic route was developed for the construction of isoxazolin-5-one glucosides using a cascade reaction. An X-ray crystal structure analysis of a isoxazolin-5-one glucoside confirmed the structure and stereochemistry of the heterocycle. The properties of the α- and β-anomers of the isoxazolin-5-one glucosides were compared. The first synthesis of 2-[6′-(3″-nitropropanoyl)-β-d-glucopyranosyl]-3- isoxazolin-5-one was realized by direct enzymatic esterification without need of further protective groups. © 2013 American Chemical Society.


Schmidt P.,Lausitz University of Applied science | Schoneich M.,TU Dresden | Bawohl M.,Institute for Inorganic and Analytical Chemistry | Nilges T.,TU Munich | Weihrich R.,University of Regensburg
Journal of Thermal Analysis and Calorimetry | Year: 2012

Several methods are established in thermal analysis to investigate phase formation, phase transition, and decomposition reactions. The analysis of phase equilibria with volatile components is particularly feasible by using standard method of thermogravimetry. Hardly any investigations of phase formation reactions are possible to realize if one of the components is lost by vaporization. By using the "High-Temperature Gas-Balance" (HTGB), the vapor phase is enclosed in a silica ampoule and thus forms an equilibrium gas phase in permanent contact with the solid phase. The measurement signal δmmeas is caused by change of the leverage of the horizontal balance support during evaporation and condensation. The application of the HTGB allows the analysis of solid-gas equilibria in the working range from 0.01 till 15 bar at temperatures up to 1,100 °C. The first comparison of evaporation reactions determined by standard thermogravimetric analyses and by measurements using the HTGB is given for the inorganic systems: P, As, SeO2, PtI2, and Hg/I. © Akadémiai Kiadó, Budapest, Hungary 2011.


Wagner A.C.,Institute for Inorganic and Analytical Chemistry | Croll A.,Albert Ludwigs University of Freiburg | Gonik M.A.,Center for Material Researches | Hillebrecht H.,Institute for Inorganic and Analytical Chemistry | And 2 more authors.
Journal of Crystal Growth | Year: 2014

In this work we made a first attempt to grow Si1-xGexsingle crystals by the so called modified float zone technique [1], without contact of container walls, using a modified AHP (axial heat flux close to the phase interface) heater. This method was derived from the "modified Bridgman" technique using a submerged heater [2]. Some advantages of this method are the improvement in crystal quality [3,4], the reduction of the radial temperature gradient and with it the reduced radial segregation during the growth experiment. For comparison another Si1-xGexcrystal was grown by the conventional float zone method, using a residual spark plasma sintered feed rod from the initially described growth experiment. Spark plasma sintering is a synthesis and consolidation technique using a pulsed current and an axial pressure to activate the sintering process [5]. Both samples were characterized by EDX, ICM, Raman and Photoluminescence spectroscopy for the purpose of analyzing the crystal quality. The use of spark plasma sintered raw material as feed material was investigated. © 2013 Elsevier B.V.


Wagner A.C.,Institute for Inorganic and Analytical Chemistry | Croll A.,Institute for Geo and Environmental Natural science | Croll A.,Albert Ludwigs University of Freiburg | Hillebrecht H.,Institute for Inorganic and Analytical Chemistry | Hillebrecht H.,Albert Ludwigs University of Freiburg
Journal of Crystal Growth | Year: 2016

The availability of suitable feed rods for Si-Ge bulk crystal growth is known to be a limiting factor in floating zone growth and other growth techniques. In this work, three Si-rich SiGe single crystals were crystallized by an optical floating zone technique in a double ellipsoid mirror furnace. The feed rods were prepared by pre-synthesis in the Spark Plasma Sintering (SPS) process starting with powders of different compositions. In a detailed section the preparation method of consolidation by mechanical alloyed powders to feed rods will be given. Results from two growth experiments starting with uniform compositions with 11 at% and 20 at% germanium as well as a zone leveling experiment with a segmented feed rod consisting of a starting zone with 32 at% Ge will be discussed. The latter experiment resulted in a crystal with nearly no axial segregation. © 2016 Published by Elsevier B.V.

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