A methodology for investigating new nonprecious metal catalysts for PEM fuel cells.

This paper reports an approach to investigate metal-chalcogen materials as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The methodology is illustrated with reference to Co-Se thin films prepared by magnetron sputtering onto a glassy-carbon substrate. Scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) have been used, in parallel with electrochemical activity and stability measurements, to assess how the electrochemical performance relates to chemical composition. It is shown that Co-Se thin films with varying Se are active for oxygen reduction, although the open circuit potential (OCP) is lower than for Pt. A kinetically controlled process is observed in the potential range 0.5-0.7 V (vs reversible hydrogen electrode) for the thin-film catalysts studied. An initial exposure of the thin-film samples to an acid environment served as a pretreatment, which modified surface composition prior to activity measurements with the rotating disk electrode (RDE) method. Based on the SAM characterization before and after electrochemical tests, all surfaces demonstrating activity are dominated by chalcogen. XRD shows that the thin films have nanocrystalline character that is based on a Co(1-x)Se phase. Parallel studies on Co-Se powder supported on XC72R carbon show comparable OCP, Tafel region, and structural phase as for the thin-film model catalysts. A comparison for ORR activity has also been made between this Co-Se powder and a commercial Pt catalyst.

Tracking responses related to self-recognition: a frequency comparison of responses to mirrors, photographs, and videotapes by cotton top tamanins (Saguinus oedipus).

The frequency of responses cotton top tamarins (Saguinus oedipus) emitted indicative of self-recognition to a mirror was compared with the frequencies of responses emitted to digitized photographs of tamarins (Experiment 1) and to videotapes of real-time or prior tamarin action (Experiment 2). Results indicated more attentional responses toward the mirror in both studies, but behavioral indices of self-recognition were not consistently generated by the mirror. The 2 experiments confirmed that real-time self-reflection is a condition that generates heightened attention and rare examples of particular mirror-specific behaviors in tamarins.

Effects of surface compression strengthening on properties of indium tin oxide films deposited on automobile glass.

Indium tin oxide (ITO) films were deposited onto automobile glass substrates with dc reactive sputtering and ion-assisted e-beam-gun evaporation processes. The ITO-coated glass samples were then strengthened through a surface compression strengthening process that included heating the glass at 650 °C for 5 min and rapidly cooling the exterior of the hot glass with air jets. The deterioration of electrical and optical properties of the ITO films on automobile safety glass was found during the heating stage of the strengthening process. When a layer of SiO(2) barrier was added, the property deterioration could be significantly reduced. The most effective barrier thickness was found near 60 nm, which resulted in no appreciable property loss.

Absorbing filter to flatten gaussian beams.

An absorbing filter that flattens the Gaussian intensity profile of a laser beam has been developed. The filter was fabricated by dc magnetron sputtering a thin tantalum film, by using a combination of substrate masking and motion. A model of the filter production has been developed that successfully predicts the film profile and performance. A typical filter produced by using these techniques results in a flat output to within +/-3% over a 2.2 mm with a transmission of 60% of the peak intensity of the Gaussian beam.

Use of the 4 x 4 matrix method in the optics of multilayer magnetooptic recording media.

The new 4x4 matrix method described by Lin-Chung and Teitler [P. J. Lin-Chung and S. Teitler, J. Opt. Soc. Am. A 1, 703 (1984)] is used to study the optics of multilayer magnetooptic recording media. It is demonstrated that the method is capable of handling very complicated optical multilayer structures. For a quodrilayer magnetooptic recording system consisting of an overcoat layer, a magnetic layer, an intermediate dielectric layer, and a reflector, the readout of the system is optimized against the thickness of the overcoat and intermediate layers. As well, cases of oblique angle of incidence, anisotropy in the nonmagnetic part of the dielectric constants, and misalignment of the magnetization are treated.