In this study PM2.5 and other five air pollutants (i.e. SO2, NO2, PM10, CO, and O3) have been analyzed by using statistical methods. Two different regression models were established quantitatively in this paper to find out the factors and causes of PM2.5 and were compared by using the partial data from January 1 to August 26, 2013, which is obtained from Wuhan Environmental Protection Bureau. The results indicate that the correlation coefficients of PM2.5 and other four air pollutants CO, SO2, NO2, and PM10 are all over 0.7, which shows significant linear correlations, and regression models were proved illustrious and accurate by testing and contrast.
Micropumps represent one of the major components in microfluidic technology. This paper describes the fabrication and performance testing of a simple, compact, inexpensive and disposable micropump suitable for microfluidic applications. The micropump was fabricated with polydimethylsiloxane (PDMS) which was bonded permanently on glass substrate. Piezoelectric-discs were used to actuate the micropumps. As a flow-rectifying element, the diffusers were used instead of passive check valves. The performances of the micropump, such as pump rate, were characterized. The flow rate of micropump increases with enhancing the applied voltage to piezoelectric-disc due to the increase of diaphragm deflection. The flow rate of the micropump with diffusers were about 9 μl/min when applying a 20 V square wave driving voltage at 300 Hz. This prototype can be used as a platform to develop an inexpensive micropump which is suitable to be part of a disposable microfluidic system.
Diurnal variations and personal exposure of carbonyl compounds were investigated in four types of large shopping malls (including department store, supermarket, bookstore and furniture store) in urban district of Nanchang, China. The diurnal measurements both in the summer and winter showed that the concentrations of carbonyls exhibited a higher peak at the morning hour and a lower peak at the evening hour except for acetaldehyde, which obviously peaked at the afternoon hour in winter. The indoor concentrations of LMW carbonyl compounds were found higher than their outdoor counterparts with only a few exceptions. For some high molecular weight (HMW) carbonyls (C5) especially for benzaldehyde and p-Tolualdehyde which might have stronger outdoor source (e.g. vehicle exhaust), resulting in the Indoor/Outdoor ratios below 1. The personal exposures showed that large shopping malls in Nanchang were important microenvironment for exposure to formaldehyde and acetaldehyde.
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