Tropopause temperatures (TPTs) control the amount of stratospheric water vapour, which influences chemistry, radiation and circulation in the stratosphere, and is also an important driver of surface climate. Decadal variability and long-term trends in tropical TPTs as well as stratospheric water vapour are largely unknown. Here, we present for the first time evidence, from reanalysis and state-...

In this study, antimicrobial activity and morphostructural damages due to lemon grass oil (LGO) and its vapour (LGOV) against Escherichia coli strains were investigated. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of LGO were determined by broth-dilution method to be 0.288 mg/mL and 0.567 mg/mL, respectively. Furthermore, the zone of inhibition (45 mm) du...

The paper reports pressure drop data for hydrocarbon fluids boiling in vertical upflow in a 8.68 m long, 25.4 mm i.d. tube, heated by direct electrical heating. These data were recorded simultaneously with the boiling heat transfer measurements. The systematic trends of the measured pressure gradient with respect to vapour quality, mass flux and pressure are examined. This provides useful infor...

This work represents a complete study of GaN annealed in H2, HCl, NH3 and N2. The GaN thermal behavior was evaluated by comparison of MOCVD and HVPE samples. The MOCVD films were found to obey a dissociative sublimation mechanism with only gaseous species forming, while the HVPE films reacted with ambient gases to form condensed Ga in addition to the gaseous species. Differences in crystal qual...

This work represents a complete study of GaN annealed in H2, HCl, NH3 and N2. The GaN thermal behavior was evaluated by comparison of MOCVD and HVPE samples. The MOCVD films were found to obey a dissociative sublimation mechanism with only gaseous species forming, while the HVPE films reacted with ambient gases to form condensed Ga in addition to the gaseous species. Differences in crystal qual...

A technique was developed to deposit GaN on a Si(1 1 1) substrate by a four-step process in a single reactor: formation of ultra-thin oxide, conversion to an oxynitride via NH3 exposure at the onset of growth, low-temperature MOCVD of GaN, followed by HVPE of GaN. It was found that this oxynitride compliant layer served to relieve stress at the GaN/Si interface as well as protect the Si substra...

The coordination of veins and stomata during leaf acclimation to sun and shade can be facilitated by differential epidermal cell expansion so large leaves with low vein and stomatal densities grow in shade, effectively balancing liquid- and vapour-phase conductances. As the difference in vapour pressure between leaf and atmosphere (VPD) determines transpiration at any given stomatal density, we...

A prism coupling method was used to measure the ordinary (no) and extraordinary (ne) refractive indices of AlxGa12xN films, grown by hydride vapor phase epitaxy ~HVPE! and metalorganic chemical vapor deposition ~MOCVD! on sapphire, at several discrete wavelengths from 442 nm to 1064 nm. In addition, spectroscopic transmittance and reflectance, correlated with the prism coupling results, were us...