We report a treatment that enhances and stabilizes the photoluminescence (PL) from porous Si films. Films prepared by anodization in a 50% HF/ethanol solution were annealed at 450 “C! in vacuum, exposed to air, and then exposed to a remote-hydrogen plasma. Infrared absorption spectroscopy revealed that the concentration of oxygen, rather than hydrogen, was increased by the processing steps, and...

Numerical simulations have been carried out for spontaneous ignition of pressurized hydrogen release directly into air. Results showed a possible mechanism for spontaneous ignition due to molecular diffusion. To accurately calculate the molecular transport of species, momentum and energy in a multi-component gaseous mixture, a mixture-averaged multi-component approach was employed in which ther...

In this letter, pronounced hysteresis loops were observed in single-walled carbon nanotube-based field-effect transistors CNTFETs . The shift in threshold voltage was found to increase with increasing gate voltage sweep ranges. A significant enhancement in the charge storage stability over 14 days was obtained at room temperature after a two-stage hydrogen and air annealing process was applied ...

Concentrations of airborne particulate matter with an aerodynamic diameter less than 10 μm (PM10) and five gaseous air pollutants (O3, CO, NO2, SO2 and H2S) were measured over a period of approximately six years (October 1999-June 2004) at five air quality monitoring network stations of King Abulaziz City for Science and Technology (KACST) in Riyadh city, Saudi Arabia. The main objective of thi...

Surface partitioning of 2,2,6,6-tetramethyl-1-piperidynyloxy radical (Tempo) to the air/water interface follows a Langmuir isotherm. The partition constant was obtained by the surface tension measurements in the concentration range of 1.0 x 10(-4)-2.4 x 10(-3) M yielding K = 640 +/- 99 M(-1). The lateral mobility of Tempo at the air/water interface was measured electrochemically in the surface ...

This paper applies multivariable robust control strategies to a proton exchange membrane fuel cell (PEMFC) system. From the system point f view, a PEMFC can be modeled as a two-input-two-output system, where the inputs are air and hydrogen flow rates and the outputs are cell oltage and current. By fixing the output resistance, we aimed to control the cell voltage output by regulating the air an...

[1] The hydrogen isotopic composition of water vapor entering the stratosphere provides an important constraint on the mechanisms for dehydration of air ascending through the tropical tropopause layer. We have inferred the annual mean hydrogen isotopic composition of water vapor entering the stratosphere (or dD-H2O0) for the mid to late 1990s based on high-precision measurements of the hydrogen...

-Recent measurements in turbulent, single-phase, reacting flows are reviewed. Attention is confined to nonpremixed flows at the fast reaction limit, which is defined as conditions where rates of reaction are fast enough to maintain local equilibrium. Reactant combinations considered include: hydrogen/air, carbon monoxide/air, hydrogen/fluorine, nitric oxide/ozone, acid/base (in liquids) and the...

Cystic fibrosis (CF) patients characteristically have severe chronic airway inflammation associated with bacterial infection. A noninvasive marker of airway inflammation could be a useful guide to treatment of CF lung disease. The aim of this study was to assess whether measurement of hydrogen peroxide (H2O2) and nitric oxide (NO) in exhaled air can serve to monitor the effect of treatment with...