A spinel ferrite/hercynite water-splitting redox cycle

Cobalt ferrites are deposited on Al₂O₃ substrates via atomic layer deposition, and the efficacy of using these in a ferrite water splitting redox cycle to produce H₂ is studied. Experimental results are coupled with thermodynamic modeling, and results indicate that CoFe₂O₄ deposited on Al₂O₃ is capable of being reduced at lower temperatures than CoFe₂O₄ (200–300 °C) due to a reaction between the ferrite and substrate to form FeAl₂O₄. Although the reaction of FeAl₂O₄ and H₂O is not as thermodynamically favorable as that of FeO and H₂O, it is shown to be capable of splitting H₂O to produce H₂ if non-equilibrium conditions are maintained. Significant quantities of H₂ are produced at reduction temperatures of only 1200 °C, whereas, CoFe₂O₄ produced little or no H₂ until reduction temperatures of 1400 °C. CoFe₂O₄/Al₂O₃ was capable of being cycled at 1200 °C reduction/ 1000 °C oxidation with no obvious deactivation.     

Preparation and Thermoplastic Processing of Modified Plant Proteins

Native plant proteins such as gluten, zein, soy and pea protein were chemically modified by acylation reactions using palmitic acid chloride and alkenyl‐substituted succinic anhydrides, respectively. The goal of this work was the development of novel, biodegradable protein materials, which are processable by thermoplastic shaping in extruders. Structures and properties of modified plant proteins were characterized by elementary analysis, IR, DSC, TGA, water retention analysis, and tensile tests. The biodegradability of the acylated protein derivatives has been demonstrated. It can be concluded that the chosen plant proteins are suitable for acylation reactions leading to fusible thermoplastic materials with improved water‐resistance. However, resultant extruded articles possess mostly high brittleness combined with low tensile strength. An improved processability and mechanical performance of the acylated products can be achieved by addition of only 10% glycerol.

     

Glow discharge techniques in the chemical analysis of photovoltaic materials

The presented study gives an integrated overview on the prospects of glow discharge (GD) methods in the chemical analysis of photovoltaic materials. With a focus on recent research and important photovoltaic (PV) materials, the GD coupled analytical methods, high resolution mass spectrometry (MS), time‐of‐flight‐mass spectrometry (TOF‐MS) and optical emission spectrometry (OES) are discussed. Each exemplary study carried out will point out the most suitable GD technique for the problem at hand, at the same time showing ways to increase analytical accuracy and to overcome typical instrumental restrictions. Challenging GD‐MS analyses of thin and ultra thin films (down to 20 nm) as well as GD‐MS and GD‐OES studies of ready‐to‐use modules were carried out, showing the reader the application potential of GD methods in a PV development or production process. For the first time, novel cell concepts based on crystalline silicon on glass and silicon nanowires are analyzed by GD‐OES, revealing precise chemical information on the devices. Copyright © 2012 John Wiley & Sons, Ltd.     

Functionalized gold nanoparticles: a detailed in vivo multimodal microscopic brain distribution study

In the present study, the in vivo distribution of polyelectrolyte multilayer coated gold nanoparticles is shown, starting from the living animal down to cellular level. The coating was designed with functional moieties to serve as a potential nano drug for prion disease. With near infrared time-domain imaging we followed the biodistribution in mice up to 7 days after intravenous injection of the nanoparticles. The peak concentration in the head of mice was detected between 19 and 24 h. The precise particle distribution in the brain was studied ex vivo by X-ray microtomography, confocal laser and fluorescence microscopy. We found that the particles mainly accumulate in the hippocampus, thalamus, hypothalamus, and the cerebral cortex.     

Modification of interparticle forces for nanoparticles using atomic layer deposition

Silica and titania nanoparticles were individually coated with ultrathin alumina films using atomic layer deposition (ALD) in a fluidized bed reactor. The effect of the coating on interparticle forces was studied. Coated particles showed increased interactions which impacted their flowability. This behavior was attributed to modifications of the Hamaker coefficient and the size of nanoparticles. Stronger interparticle forces translated into a larger mean aggregate size during fluidization, which increased the minimum fluidization velocity. A lower bed expansion was observed for coated particles due to enhanced interparticle forces that increased the cohesive strength of the bed. Increased cohesiveness of coated powders was also determined through angle of repose and Hausner index measurements. The dispersability of nanopowders was studied through sedimentation and z-potential analysis. The optimum dispersion conditions and isoelectric point of nanoparticle suspensions changed due to the surface modification. A novel atomic force microscope (AFM) technique was used to directly measure interactions between nanoparticles dispersed on a flat substrate and the tip of an AFM cantilever. Both Van der Waals and electrostatic interactions were detected during these measurements. Long and short range interactions were modified by the surface coating.