Condom use: A self-efficacy model.

A survey of heterosexually active college students gathered information about condom use, self-efficacy (SE), outcome expectancies, sexual attitudes, peer group influences, AIDS knowledge, and a perceived vulnerability to AIDS. On the basis of A. Bandura's (1986) social-cognitive theory, a structural model with SE as the central mediator was formulated and evaluated with LISREL. This model explained 46% of the variance in condom use from judgments of SE and effects attributable to peers and 53% of the variance in SE from outcome expectancies and peer group influences. Sexual attitudes, AIDS knowledge, and perceived vulnerability did not predict condom use. Most students were well-informed about HIV transmission but reported not feeling at risk, even though many engaged in risky sexual behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mixed design approach for probabilistic structural durability

In this paper, a mixed approach for probabilistic structural durability design of mechanical systems is proposed. In this approach, a deterministic design optimization that considers structural crack initiation and crack propagation lives at critical points of the structural component as design constraints is performed first. After an optimal design is obtained, a reliability analysis is performed to ascertain if the deterministic optimal design is reliable. If the probability of the failure of the deterministic optimal design is found to be acceptable, a reliability-based design approach that employs a set of interactive design steps, such as trade-off analysis and what-if study, is used to obtain a near-optimal design that is reliable with an affordable computational cost. A 3-D tracked vehicle roadarm is employed to demonstrate the feasibility of the proposed approach.     

Parasitic-aware RF circuit design and optimization

RF circuit synthesis techniques based on particle swarm optimization and adaptive simulated annealing with tunneling are described, and comparisons of parasitic-aware designs of an RF distributed amplifier and a nonlinear power amplifier are presented. Synthesized in 0.35-/spl mu/m digital CMOS using a single 3.3-V power supply, the designs provide an 8-dB gain and 8-GHz bandwidth for a four-stage distributed amplifier, and 1.2-W output power with 55% drain efficiency at 900 MHz for a three-stage power amplifier. A standard circuit simulator, HSPICE or SPECTRE, embedded in an optimization loop is used to evaluate cost functions. The proposed design and optimization methodology is computationally efficient and robust in searching complex multidimensional design spaces.     

Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO2 for no reduction by NH3

Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO₂ for NO reduction by NH₃ was examined in a fixed-bed flow reactor. The deactivation of the catalyst was strongly dependent on reaction temperature. At high reaction temperatures over 300°C, the catalyst did not lose its initial activity up to 50 h of operation, regardless of SO₂ feed concentration from 500 to 20,000 ppm. However, at low reaction temperatures near 250°C, apparent deactivation did occur. Changes in the physicochemical properties such as surface area and sulfur content of deactivated catalyst well correlated with catalyst activity, depending upon reaction temperatures. The deactivation was due to pore blocking and/or filling by deactivating agents, which plugged and/or filled the pores of catalyst. The deactivating agents deposited on the catalyst surface were presumed to be (NH₄)₂SO₄ and/or (NH₄)HSO₄ from the results of TGA and ion-chromatography measurement.     

Parathion degradation and toxicity reduction in solar photocatalysis and photolysis.

The solar photocatalytic degradation of methyl parathion was investigated using a circulating TiO2/solar light reactor. Under solar photocatalysis condition, parathion was more effectively degraded than solar photolysis and TiO2-only conditions. With solar photocatalysis, 20 mg/L of parathion was completely degraded within 60 min with a TOC decrease of 63% after 150 min. The main ionic byproducts during photocatalysis recovered from parathion degradation were mainly as NO3-, NO2- and NH4+, 80% of the sulphur as SO4(2-), and 5% of phosphorus as PO4(3-). The organic intermediates 4-nitrophenol and methyl paraoxon were also identified, and these were further degraded in solar photocatalytic condition. Two different bioassays (Vibrio fischeri and Daphnia magna) were used to test the acute toxicity of solutions treated by solar photocatalysis and photolysis. The Microtox test using V. fischeri showed that the toxicity expressed as EC50 (%) value increased from 5.5% to >82% in solar photocatalysis, indicating that the treated solution is non-toxic, but only increased from 4.9 to 20.5% after 150 min in solar photolysis. The acute toxicity test using D. magna showed that EC50 (%) increased from 0.05 to 1.08% under solar photocatalysis, but only increased to 0.12% after 150 min with solar photolysis, indicating the solution is still toxic. The pattern of toxicity reduction parallels the decrease in TOC and the parathion concentrations.     

Fabrication and performance of parallel-addressed InGaN micro-LED arrays

High-performance, two-dimensional arrays of parallel-addressed InGaN blue micro-light-emitting diodes (LEDs) with individual element diameters of 8, 12, and 20 /spl mu/m, respectively, and overall dimensions 490 /spl times/490 /spl mu/m, have been fabricated. In order to overcome the difficulty of interconnecting multiple device elements with sufficient step-height coverage for contact metallization, a novel scheme involving the etching of sloped-sidewalls has been developed. The devices have current-voltage (I-V) characteristics approaching those of broad-area reference LEDs fabricated from the same wafer, and give comparable (3-mW) light output in the forward direction to the reference LEDs, despite much lower active area. The external efficiencies of the micro-LED arrays improve as the dimensions of the individual elements are scaled down. This is attributed to scattering at the etched sidewalls of in-plane propagating photons into the forward direction.