Morphology controlled deposition of ZnO single micro-nanorods

The ZnO micro-nanorods are controlledly synthesized by a simple chemical vapor deposition method. With different oxygen concentrations the micro-nanorods exhibit different extrinsic feature and length. Under lower oxygen concentration, the micro-nanorods are up to 1670 μm in length which can be easily operated in singlecrystalline. When the oxygen concentration up to 30 sccm, the surface of the sample is smoother. The Raman spectra reveal that ZnO micro-nanorods have an excellent hexagonal wurtzite structure. However, the micronanorods synthesized during lower oxygen concentration exhibit more oxygen defect. The morphology controlling deposition of ZnO mircro-nanorods were realized by adjust the concentration of oxygen, which has great significance for further gas sensor application.

Numerical Model for Nitrogen Tire Inflation5

The scope of this study was twofold: (1) to quantify the contribution nitrogen inflation would have on oxidative aging of tires and (2) measure the improvement nitrogen tire inflation may have on inflation pressure retention. A previously developed tool for diffusion-limited oxidation was used to simulate aging behavior at 25 and 60 °C. Oven-accelerated tire aging (60 °C) data for different inflation media was used for successful validation of the model, and it was shown that aging rates for higher oxygen concentrations tend toward a constant value. For lower temperatures, the use of nitrogen was shown to produce lower oxygen concentration in the wedge and bead regions of the tire geometry considered when compared to air inflation. By using 95% pure nitrogen (that is, the actual nitrogen concentration in the tire cavity), a 25% reduction in aging rate (for the tire wedge) and a 35% reduction in the initial flux of mass out of the tire (a measure of inflation pressure retention) were calculated.

Alternative Group V Precursors for the Growth of Al-Based III-V Epitaxial Layers by OMVPE

ABSTRACTTertiarybutylarsine (TBAs), tris-dimethylaminoarsenic (DMAA), and tertiarybutylphosphine (TBP) were investigated as alternatives to arsine and phosphine for the growth of AlGaAs, AlInAs, and AlInP by organometallic vapor phase epitaxy. The use of TBAs led to a significant reduction in carbon and oxygen incorporation compared to ASH3 for AlGaAs. Increasing the TBAs molar flow rate reduced the oxygen (and carbon) concentration. Lower oxygen concentration was observed in AllnP grown with TBP compared to PH3. Increasing the PH3 molar flow rate decreased the oxygen incorporation in AllnP. The morphology of AllnP improved considerably as the growth temperature was increased from 650°C to 750°C, similar to the case of PH3. AlInAs and AlGaAs layers grown with DMAA exhibited rough morphology, presumably due to oxygen-containing impurities in the DMAA source.

Respiratory Regulation in Ephemera Simulans Walker and Hexagenia Limbata (Serville) (Ephemeroptera)

1. This study shows that Ephemera simulans and Hexagenia limbata are respiratory regulators and how it is that regulation is attained and maintained. 2. Nymphs, 17-24 mm. in length, were acclimated in the laboratory at 13.o° C. for 24 hr. Oxygen consumption experiments employed the ‘closed-bottle’ technique and several modifications. 3. When studied in bottles containing no substrate, both species appeared to be respiratory adjustors. 4. Using ‘optimal substrates’ and a wide range of oxygen concentrations, both species proved to be respiratory regulators. 5. As the oxygen concentration decreased, respiratory regulation was attained by initiating and increasing a flow of water past the body surfaces by the bailer action of beating gills. The volume passed was proportional to the number of gill beats which, in turn, was influenced by the size of the gills. The larger gills of Hexagenia beat at a slower rate to produce the same current as Ephemera and potentially they were capable of producing a significantly greater current and, hence, could regulate to a lower oxygen concentration.