Investigation of nucleation centres in diamond chemical vapour deposition with spatially resolved X-ray photoelectron spectroscopy

The nucleation of diamond films on silicon substrates deposited by hot filament chemical vapour deposition has been investigated for the first time with an X-ray photoelectron spectroscopy microscope. The distribution of carbon, oxygen, silicon and tungsten on the surface was imaged with a spatial resolution of 10 μm. Significant differences were found between untreated areas of the substrates and scratches created by a diamond tip. Our data reveal that material from the tip abraded in the scratching process is not of key importance for nucleation.     

Assessment of an experimental bone wax polymer plus TGF-beta 1 implanted into calvarial defects

The study reported describes an experimental biodegradable polymer ceramic composite with wax-like handling properties that was combined with 2.0 micrograms of recombinant human transforming growth factor beta (rhTGF-beta(1)). The polymer/rhTGF-beta(1) combination was introduced into standard-sized calvarial defects in rabbits to evaluate biodegradability, biocompatibility, hemostasis control, and bone promotion. The experimental wound model was a standard-size circular calvarial defect 8 mm in diameter. The experimental design included 24 skeletally mature New Zealand white rabbits divided evenly between two time periods (6 and 12 weeks) and among three experimental treatments (untreated defects and defects treated with polymer with or without rhTGF-beta(1)). Evaluations consisted of clinical examinations, standarized radiography, radiomorphometry, as well as histology and histomorphometry. Data were analyzed by an Analysis of Variance (ANOVA) and Fisher's Protected Least Significant Difference test at each time period (level of significance p < or = 0.05). Radiomorphometry data indicated that standard-sized defects treated with the wax-like polymer alone and the polymer plus 2.0 micrograms of TGF-beta(1) were significantly more radiopaque than control sites at both 6 and 12 weeks. Histomorphometric data revealed the amount of new bone was significantly greater at 6 weeks in the polymer plus 2.0 micrograms of TGF-beta(1) and in the control group than in the polymer alone. Moreover, at 12 weeks, there was significantly more new bone in the control than in either the polymer alone or the polymer plus 2.0 micrograms of TGF-beta(1). We speculate the incomplete biodegradation of the polymer ceramic composite contributed to the radiopacity and may have retarded osseous regeneration. It is important that the bone wax-like polymer material was biocompatible and acted as a hemostatic agent.     

Application of glow discharge polymerisation to the preparation of reverse osmosis membranes

Reverse osmosis membranes have been prepared by the deposition of thin films on to the surface of a porous support membrane by glow discharge polymerisation. A film prepared from vinylene carbonate with the addition of 8% acrylonitrile was found to give the best salt rejection; salt rejection increased with the number of polymer coats deposited.     

The public cryptography study group

The Public Cryptography Study Group was created by the American Council on Education in the spring of 1980 to examine concerns expressed by the Director of NSA caused by the rapid growth of interest in cryptology as a means for the protection of data files. Written by a participant in the study, this paper discusses many of the issues that came before the committee, including the danger to security systems produced by inadvertent or malicious disclosure of weak points in the system which would render it ineffective. It concludes by summarizing the recommendations in the final report of the PCSG, and describes the implementation of the voluntary review procedure recently announced by the Director of NSA. The procedures are designed to decrease the danger to public, private and governmental national security, without impeding the growth of nongovernmental research.     

Generalizability of locus of control: A Rep Grid investigation of personality consistency.

Developed 2 measures based on G. A. Kelly's Rep Grid Test, one dealing with personal events and the other with general societal events. Results from 258 undergraduates show that internals used significantly more internal constructs than did externals and that Ss chose more internal constructs on the personal than on the societal measure. Results suggest that the internal-external dichotomy is reflected in and may be mediated by modes of thinking and categorization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)