Characterization of TiO2 and ZrO2 coatings on silica slabs and fibres

Titanium and zirconium dioxide coatings were deposited on optical fibres by the sol-gel procedure. The thickness of the layers on fibres was established by measurement of the intensity of characteristic X-rays by an electron microprobe analyser. The accuracy of the measurements was verified on broken layers by scanning electron microscopy. Also determined were the thicknesses of similar layers deposited on flat silica substrates with an ellipsometer and stylus surfometer as well as from reflectivity spectra and from specular total reflection of X-rays. The densities of TiO₂ and ZrO₂ layers on silica glass slabs were determined by X-ray total reflection. Values of 3.16 ± 0.02 and 4.69 ± 0.03 gm cm^–2 were found for titania and zirconia, respectively. The crystallinity of layers on silica plates was investigated by Raman spectroscopy. The thicknesses of coatings prepared by the dipping technique were related to the withdrawal speed. Equations for Newtonian and non-Newtonian fluids were tested and compared. A pseudo-plastic behaviour was suggested for all the solutions used in the experiments.     

Review of Nonverbal behavior: Perspectives, applications, intercultural insights.

Reviews the book, Nonverbal behavior: Perspectives, applications, intercultural insights edited by Aaron Wolfgang (1984). This book contains articles based on the papers presented at the Second International Conference on Nonverbal Behavior held at OISE in Toronto in May 1983. The fifteen articles, most of them by well-known figures in the nonverbal area, are divided into three separate sections: theoretical perspectives; nonverbal behaviour in teaching, therapy, and research; and intercultural applications of nonverbal research. The current volume is similar to an earlier work documenting the First International Conference on Nonverbal Behavior (both conferences were organized by Aaron Wolfgang) but differs in some significant ways: specifically, the current book is much more focused on intercultural communication; it expands the range of topics to include paralanguage and gender differences in nonverbal behaviour; and finally, it reflects more accurately the significant number of female researchers in the field. Those with a good background in the field should find some of the articles helpful updates, although perhaps not detailed enough to be as useful as possible. On the other hand, those fresh to the nonverbal area should find certain articles stimulating, particularly those with an intercultural focus, but might find the lack of historical or theoretical organization an unfortunate omission. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-Dependent Rheological Properties of Semi-Solid Metal Alloys

Semi-solid metal alloys, as used in thixoforming, have a special microstructure of globular grains suspended in a liquid metal matrix. The complex rheological properties are strongly influenced by the local solid fraction, particle shape, particle size and state of agglomeration. There is a high demand for models and software tools allowing the simulation of semi-solid casting processes. The material under investigation is a tin-lead alloy (Sn-15%Pb) which exhibits a similar microstructure to aluminium alloys. The experiments were performed with a concentric cylinder rheometer of the Searle type. Initially, the liquid alloy is cooled down to the semi-solid range under constant shearing and then kept under isothermal conditions for further experimentation. Based on the experimental data, a single-phase model has been derived where the semi-solid alloy is regarded as a homogeneous material with thixotropic properties and the microstructure is characterised by a structural parameter. The model consists of two parts: the equation of state, including a finite yield stress, and a rate equation for the structural parameter. The model equations are employed in numerical software and used for the simulation of characteristic filling cases and the comparison with the conventional filling.