Processing of non-oxidic powders in water. Part 1

To suppress the reactivity of nanoscaled non-oxidic powders such as titanium nitride and silicon carbonitride against hydrolysis and oxidn., chem. surface modification with nitrogen contg. surfactants was investigated. Among these surfactants long chain primary amines, ethylene diamines and isocyanates were examd. Thermogravimetry, elemental anal. and the behavior against water vapor adsorption of the modified particles were used as methods to est. the protective capacity of the org. coating material. Best results were obtained by using a long chain ethylene diamine, which was indicated by a significant redn. of the powder oxidn. and an increase in particle hydrophobicity. Prepn. of a stable aq. dispersion without significant changes in the elemental compn. of the powder was achieved by application of water sol. surfactants to the surface modified particles. Very good results were obtained by application of an emulsion technique

Verbesserung der Explosionschutzmassnahmen im Streb und Streb/Streckenuebergang durch Weiterentwicklung manueller Loeschtechniken und der automatisch ausloesenden Wassertrogsperre sowie Konzeption und Erprobung eines aktiven Explosionsschutzes mit Hilfe der Wassernebeltechnik

The explosion protection and fire extinction investigations comprised three sections: 1. Manual extinction techniques. Different types and arrangements of nozzles were investigated for their efficiency in gas fire extinction at different air flow rates. Although all systems were tested satisfactorily, high-pressure systems are recommended as they have a longer range. 2. Explosion protection in the T-junction area with the aid of water trough extinction systems were investigated. A system of this type is described, and background information and the general principle are presented. 3. Methane ignition is a hazard that can not be prevented, but most ignitions in the past were local, so that manual extinction by the mining staff can be recommended. A training programme was developed on the basis of the available long-year experience.SIGLEAvailable from TIB Hannover: RR 1344(138) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekLand Nordrhein-Westfalen, Duesseldorf (Germany)DEGerman

Evaluation of the toxic potential of different nanoparticles in neuronal and glial cell cultures

The aim of this study is to investigate neurotoxicity and gliotoxicity of nanoparticles to which humans may be exposed in the context of medical applications, during manufacturing processes or by using nanoparticle containing products. In vivo studies have shown that nanoparticles can be found within the brain of exposed animals. However, there is little known about the interaction of nanoparticles with neurons and glial cells. So far we assessed the effects of nanoscaled tungsten carbide [WC], nanoscaled tungsten carbide cobalt [WC-Co], which are released during the manufacturing process of tools, and purified single-walled carbon nanotubes [SWCNT] which are of growing interest in technical and medical investigations. Culture systems used include the oligodendrocyte cell line OLN 93, primary neuronal cultures, astrocytes and microglial cellsobtained from fetal or newborn rat brain. These cultures are exposed to nanoparticles and resulting effects are studied in a time and concentration dependent manner. To identify whether cell toxicity occurs, we applied in a first step different in vitro viability and cytotoxicity assays (CCK 8, MTT, LDH). The results show that WC nanoparticles are less toxic than WC-Co nanoparticles and SWCNT in our cell culture systems. In OLN 93 cells all analysed particles reduced cell viability significantly. Using the TUNEL assay we found a small increase in apoptotic cells following treatment with WC. Cellular uptake and distribution of the examined nanoparticles is currently analysed by electron microscopy. The obtained data of our studies suggest that nanoparticle exposure may impose a risk for the central nervous system