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.

Latest research results on the effects of nanomaterials on humans and the environment: DaNa - Knowledge Base Nanomaterials

Abstract: Nanotechnology is considered one of the key technologies of the 21st century. The success of this fascinating technology is based on its versatility. It will bring about fundamental changes of basic research as well as of many sectors of industry and also of daily life from electronics to the health care system. However, consumers often miss reliable and understandable information on nanomaterials and all aspects of this versatile technology. A huge body of data on the potential hazards of nanoobjects towards human and environmental health already exists, but is either not easily accessible for a broad audience or presented unprocessable for nonexperts. But risk communication is an essential and thus integral component of risk management. For that purpose, the DaNa-Project aims at filling this gap by collecting and evaluating scientific results in an interdisciplinary approach with scientists from different research areas, such as human and environmental toxicology, biology, physics, chemistry, and sociology. Research findings from the field of human and environmental nanotoxicology are being prepared and presented together with material properties and possible applications for interested laymen and stakeholders. For the evaluation of literature a Literature Criteria Checklist has been developed as well as a Standard Operation Procedure template (SOP) based on careful scientific practice.

Development of a metal dusting resistant functional coating by Sn and Al pack cementation

Abstract: A new coating against metal dusting is developed by the combination of a catalytic inhibition approach with a classical oxide barrier. Coatings were manufactured by co-deposition of tin and aluminum on nickel plated alloy 800H via powder pack cementation with different dwell times. The resulting coatings consist of two phases, a nickel-aluminide phase as oxide forming reservoir and an underlying nickel-tin phase which catalytically inhibits carbon deposition. Coated samples were exposed to H2-22%CO-10%H2O as a laboratory metal dusting environment as well as air at 620 °C. Cross sectional analysis revealed no sign for metal dusting and the formation of a thin alumina layer at the surface.

Liposome based solubilisation of carotenoid substrates for enzymatic conversion in aqueous media

Abstract: Enzymatic conversions of strongly hydrophobic substrates can be conducted in non-denaturing aqueous reaction media if appropriate substrate delivery systems such as micelles or liposomes are applied. We investigated liposome based substrate delivery with regard to qualitative and kinetic effects of vesicle properties on the enzymatic reaction. The cleavage of highly hydrophobic carotenoid and xanthophyll substrates by Arabidopsis thaliana carotenoid cleavage dioxygenase 1 (AtCCD1) was used as model reaction for the investigation. Conversions of the partly polar xanthophylls and the fully non-polar carotenes showed different responses to variations in the phospholipid composition of the delivery vesicles. Furthermore, the cellular reaction environment of AtCCD1 was imitated by incorporation of the galactolipid monogalactosyl-diacylglycerol (MGDG) into the liposome membranes. This led to an increase of the specific AtCCD1 activity towards the fully non-polar β-carotene by approximately 70% at MGDG shares between 8 and 20 mol% while the specific activity towards the more hydrophilic zeaxanthin decreased with increasing MGDG content. Liposome based systems proved to be less suitable for the delivery of amphiphilic and non-symmetric substrate molecules than micelles due to substrate orientation within the liposome membrane. The results represent a starting point for a systematic design of liposome based delivery of hydrophobic substrates in enzymatic conversions performed in aqueous media.

Surface modification of titanium aluminides with fluorine to improve their application for high temperature service conditions

Abstract: Recently the target temperature of components manufactured from gamma-TiAl alloys like turbine blades, turbocharger rotors or automotive valves has been increased to 900 °C. However, there is an insufficient oxidation resistance above 750 °C. One method used to improve the gamma-TiAl oxidation behaviour is the so-called fluorine microalloying effect. After application of fluorine to the TiAl surface by ion implantation or treatment with diluted HF and oxidation at 900 °C in air a dense alumina layer is formed. However, after the treatments a distinct loss of fluorine was observed during heating and within the first hours of oxidation. In this work the long time behaviour during isothermal and cyclic oxidation up to 1500 h/900 °C/air was investigated showing a slow fluorine decrease. The alumina layer acts as a diffusion barrier for fluorine, whereas fluorine diffuses into the metal. The diffusion coefficient was calculated. The results fit the theoretical model of the fluorine effect.