Bio Med Sciences (United States)

Abstract The discussion focuses on the application of a Payne cell to the measurement of diffusion and solubility coefficients in polymer/solvent systems. Payne cells have, thus far, been used exclusively to measure steady‐state permeation rates of solvents. An analytical model has been developed to describe transient gravimetric sorption and desorption measurements performed with a Payne cell. The model has been validated by a complementary numerical simulation and has been applied to evaluate diffusion and solubility coefficients in two different toluene‐silicone rubber systems. The data measured using the Payne cell are found to compare very well with diffusion coefficient and isotherm data measured by traditional gravimetric sorption experiments.

A paradigm shift in management of postburn facial scarring is lurking "just beneath the waves" with the widespread availability of two recent technologies: precise three-dimensional scanning/digitizing of complex surfaces and computer-controlled rapid prototyping three-dimensional "printers". Laser Doppler imaging may be the sensible method to track the scar hyperemia that should form the basis of assessing progress and directing incremental changes in the digitized topographical face mask "prescription". The purpose of this study was to establish feasibility of detecting perfusion through transparent face masks using the Laser Doppler Imaging scanner. Laser Doppler images of perfusion were obtained at multiple facial regions on five uninjured staff members. Images were obtained without a mask, followed by images with a loose fitting mask with and without a silicone liner, and then with a tight fitting mask with and without a silicone liner. Right and left oblique images, in addition to the frontal images, were used to overcome unobtainable measurements at the extremes of face mask curvature. General linear model, mixed model, and t tests were used for data analysis. Three hundred seventy-five measurements were used for analysis, with a mean perfusion unit of 299 and pixel validity of 97%. The effect of face mask pressure with and without the silicone liner was readily quantified with significant changes in mean cutaneous blood flow (P < .5). High valid pixel rate laser Doppler imager flow data can be obtained through transparent face masks. Perfusion decreases with the application of pressure and with silicone. Every participant measured differently in perfusion units; however, consistent perfusion patterns in the face were observed.

Abstract Despite an appropriate screening process, the potential for a misdiagnosed multiple personality to be included in a group is much higher than most therapists realize. The author describes one long-term group's experience with the emergence of two multiple personalities.

Abstract Most semiconductor devices are built in the epitaxial layer on a silicon wafer. The properties of the starting epitaxial material are important, because they help to determine the final device parameters. In order to obtain good epitaxial material, the reactants and dopants used must be of known purity. Analytical methods are not sufficiently sensitive and a Use Test has been attempted. Section 5.2 of ASTM Committee F-1, on Materials for Diffusion and Epitaxy, is at this time designing and evaluating an epitaxial reactant purity evaluator. A cleaning method has been devised, which is an important step in the Use Test.

Summary Tantalum film reactively sputtered in nitrogen is extensively used as a thin film resistor material in film integrated circuits. The control of nitrogen content is very important, since the nitrogen content of the film determines the aging characteristics, anodizability, sheet resistance, and temperature coefficient of resistance (TCR) of the film. A suitable method of identifying the nitrogen doping level of film immediately after sputtering is highly desirable. This paper describes the design and use of a diagnostic instrument called the “Seebeck apparatus,” which has been developed for this purpose. The film parameter measured is the so-called “Seebeck ratio @,” a quantity directly related to the Seebeck coefficient of the material. The instrument is capable of making measurements on as-sputtered film deposited on high resistivity substrates. The measurement is contacting but nondestructive, fast, and simple. Determination of the Seebeck ratio of film can be reproducibly made in less than 1 min and the ratio is presented as a direct digital readout. Using the Seebeck apparatus, the relationship between the Seebeck ratio and the nitrogen concentration in reactively sputtered tantalum nitride films has been examined. The nitrogen doping level of the films was controlled by varying the partial pressure of nitrogen in the sputtering system. Other material properties, such as resistivity (p), TCR, and aging were concurrently .‘examined and correlated with the Seebeck ratio. The results show that the Seebeck ratio of tantalum nitride films is a very rapidly varying function of the nitrogen doping level in the range suitable for resistor fabrication. Because of this functjonal relationship, it has been found that a measurement of the Seebeck ratio provides a much more sensitive test of whether film is suitably doped than the joint measurements of p and TCR alone.