DECHEMA

About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.

Impact of surfactants on solubilization and activity of the carotenoid cleavage dioxygenase, AtCCD1, in an aqueous micellar reaction system.

Abstract: The effect of various surfactants on both the solubilization of the carotenoid cleavage dioxygenase, AtCCD1, from cell lysates and the enzymatic activity in an aqueous micellar system was investigated. Solubilization with sodium cholate more than doubled the specific activity. Lag phases were observed when Tween surfactants were used for substrate delivery and were dependent on the surfactant and enzyme modification. In contrast to His6- and GST-tagged AtCCD1, unmodified AtCCD1 showed a 45% increased maximum rate in the Tween 20 system compared to Triton X-100 based reference system. The results emphasize the importance of engineering the interface for the in vitro application of this enzyme family.

Cr-Ge-Si Alloys for High-Temperature Structural Applications: Microstructural Evolution

Abstract: The microstructural evolution of Cr-Si1−x-Gex (0 < x < 15 at. pct) alloys was studied (in annealed state). The quasi-isothermal section of the ternary diagram was assessed by quantitative EPMA analysis. Morphology, phase formation, chemical distribution, and indentation hardness of the alloys were investigated as a function of Ge/Si ratio. The microstructure of all studied alloys consisted of Crss solid solution and A15 Cr3X intermetallic phases. Substitution of Si by Ge strongly altered the microstructure by transforming the morphology from a lamellar eutectic Cr-Cr3Si system toward a peritectic one with dispersed Crss phase in A15 matrix. EPMA chemical distribution maps and X-ray diffraction results prove the mutual solubility of Si and Ge in A15 phase by forming Cr3(Si,Ge) as a complex A15 structure with Cr3(Si1−xGex) composition. Precipitates of the intermetallic phase within the Crss phase was observed in Ge-alloyed samples. Indentation hardness results showed that upon Si-Ge substitution the hardness of both phases was reduced. However, Si substitution by Ge had a stronger influence on the hardness of the solid solution phase than on the intermetallic phase.

An Enhanced Three-Step Oxidation Process to Improve Oxide Adhesion on Zirconium Alloys

Abstract: Oxidation of zirconium-based alloys results in a thermally-grown oxide scale with excellent corrosion resistance, and good wear and friction properties, which make them interesting for tribological applications. Nevertheless, adhesion of the oxide layer to the substrate must be enhanced. A new three-step oxidation process was introduced in order to achieve an improvement. Following an initial oxidation step (1st step), a heat treatment was carried out in vacuum during which the oxide dissolves and diffuses into the metallic zirconium substrate (2nd step). These two steps resulted in an oxygen dissolution layer with increased hardness formed in-between the oxide and the substrate, which serves as a bonding layer with increased thickness. In a 3rd step a new oxide layer was obtained. The improved oxide layer adhesion was characterized by indentation tests on three different groups of oxidized samples of the newly developed alloy.