Observations of isoprene, methacrolein (MAC) and methyl vinyl ketone (MVK) at a mountain site in Hong Kong

A field campaign was carried out in September-November 2010 near the summit of Mt. Tai Mo Shan in Hong Kong. Isoprene, methyl vinyl ketone (MVK) and methacrolein (MAC) were measured. The average isoprene mixing ratio was 109 pptv, and the average MAC and MVK levels were 68 pptv and 164 pptv, respectively. The average daytime levels of isoprene (14920 pptv, average95% confidence interval, p<0.01), MAC (709 pptv, p<0.01) and MVK (16922 pptv, p<0.1) were significantly higher than the average nighttime values (205 pptv, 498 pptv and 13925 pptv, respectively). The relationship between MVK and MAC indicated that nearby isoprene oxidation dominated their daytime abundances, while NO3 chemistry and regional transport of anthropogenic sources from inland Pearl River Delta region could explain the higher MVK to MAC ratios at night. Correlation analysis of [MVK]/[isoprene] versus [MAC]/[isoprene] found that the isoprene photochemical ages were between 10 and 64min. Regression analysis of total O3 (O3+NO2) versus MVK resulted in an estimated contribution of isoprene oxidation to ozone production of 12.5%, consistent with the simulated contribution of 10-11% by an observation-based model. © 2012 American Geophysical Union. All Rights Reserved

Applying Eye Tracking in Information Security

Abstract In this paper, we are considering the possibility of using eye tracking technology in the context of information security. We expect that this novel technique will have a very effective impact in this field. Eye tracking technology is widely used to investigate user behavior when working with a computer. This technology allows to obtain analysis in the form fixation point (location of a user's eye gaze), scan-path (gaze trajectory), heat maps (areas of interest), salient picture components. Eye tracking research has been widely used to improve the design and usability of web pages, as well as to explore an understanding how users are guided by them. Moreover, this technology is widely used in the protection of information

Acetone in the Atmosphere of Hong Kong, Abundance, Sources and Photochemical Precursors

Intensive field measurements were carried out at a mountain site and an urban site at the foot of the mountain from September to November 2010 in Hong Kong. Acetone was monitored using both canister air samples and 2,4-dinitrophenylhydrazine cartridges. The spatiotemporal patterns of acetone showed no difference between the two sites (p > 0.05), and the mean acetone mixing ratios on O3 episode days were higher than those on non-O3 episode days at both sites (p < 0.05). The source contributions to ambient acetone at both sites were estimated using a receptor model i.e. Positive Matrix Factorization (PMF). The PMF results showed that vehicular emission and secondary formation made the most important contribution to ambient acetone, followed by the solvent use at both sites. However, the contribution of biogenic emission at the mountain site was significantly higher than that at the urban site, whereas biomass burning made more remarkable contribution at the urban site than that at the mountain site. The mechanism of oxidation formation of acetone was investigated using a photochemical box model. The results indicated that i-butene was the main precursor of secondary acetone at the mountain site, while the oxidation of i-butane was the major source of secondary acetone at the urban site.Department of Civil and Environmental Engineerin

Effects of Sowing Date and Phosphorus Fertiliser Application on Winter Survival of Lucerne cv. Aohan in the Northern Semi-Arid Region of China

In the northern semi-arid region of China, winter survival is always a limiting factor for lucerne production, because low temperatures and a dry climate in winter (Zhou et al., 1993; Ma, 2000; Sun & Gui, 2001; Sun et al., 2003). An experiment was conducted to find an appropriate sowing date and P application rate in order to improve lucerne winter survival

Magnetotransport and dielectric properties of perovskite ruthenate and titanate thin films

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Realization of Pan Jiazheng′s extremum principle with optimization methods

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Response of innate immune factors in abalone Haliotis diversicolor supertexta to pathogenic or nonpathogenic infection

Cell free hemolymph from Haliotis diversicolor supertexta was prepared from fluid collected at 1, 4, 8. 12. 24, 48 96 It after injection with either Escherichia coli, Vibrio parahaemolyticus or 0.9 NaCl solution (control group). The response of selected innate immune parameters (lysozyme, antibacterial activity, alkaline phosphatase, acid phosphatase, phenoloxidase, and superoxide dismutase) was investigated. Results showed that the activities of ACP (Acid Phosphatase) from abalone injected with V. parahaemolyticus were much higher than that of the control group at 24 h after injection. The ALP (Alkaline Phosphatase) activities of abalone challenged with V. parahaemolyticus were significantly higher than those of the control group at 8 h and increased further up to 48 h after the challenge. In contrast, the activities of ALP and ACP in the E. coli-challenged group showed no statistically significant differences at any of the sampling times. The activities of SOD (Superoxide Dismutase) in cell free hemolymph from the V. parahaemolyticus-exposed group were significantly lower than those of the control group at both I h and 24 h, whereas there was no difference in SOD activity observed in the group exposed to E. coli at any of the sampling times. The activities of lysozyme and phenoloxidase in Haliotis diversicolor were relatively low in both control and bacteria-ex posed groups when compared with reports for other invertebrates no significant difference was found between the infected groups and the control for these two parameters, due to the low activities and high individual variance