No abstract

Spatial distributions of ultrafine particles (UFPs; 6 < D p < 560 nm) and related gaseous and particulate pollutants were estimated from on-road measurements undertaken on busy roadways of Seoul, Korea, using a mobile laboratory (ML). The objectives of the study were to determine the spatial variations in UFP size distributions and concentrations of associated gaseous and particulate pollutants and to observe the relationships of UFP number concentrations with other pollutants on roadways in an urban area in Korea. The pollutants associated with diesel vehicles such as black carbon (BC) and particlebound polycyclic aromatic hydrocarbons (PM-PAHs) exhibited a high determination coefficient (r 2 = 0.65), indicating the influence of diesel vehicles on emissions in the study area. Further supporting evidence for the influence of diesel vehicles on emissions was given by the higher determination coefficients of PM-PAHs and BC concentrations with larger sizeclassified particles, ranging from 60 < D p < 220 nm, than with total UFP number concentrations or smaller particles in the 6 < D p < 60 nm size range. Peak concentrations of measured pollutants were observed mostly at intersections, reflecting the relationships of transient driving modes (i.e., deceleration and acceleration) with emissions of UFPs, associated pollutants, and concentrated traffic volumes at such locations.

Recently, many studies have been focused on the development of fiber optic sensor systems for various gases and vapors. In the present study, an intrinsic polymer optical fiber (POF) sensor using graphene is described for the purpose of acetone vapor sensing for the first time. Observations on the continuous measurement of acetone vapor in dehydrated air are presented. The principle of operation of sensor transduction relies on the dependence of the reflectance on the optical and geometric properties of the sensitive over layered when the vapor molecules are adsorbed on the graphene film. For the same purpose the CVD synthesized graphene film was transferred on the POF end. The synthesized graphene film thickness was evaluated using atomic force microscopy (AFM), Raman spectroscopy and transmission electron microscopy (TEM). For the preliminary evaluation using volatile organic compounds, we evaluated the sensor performance for acetone. Upon the interaction of the sensor with acetone vapor, the variation in the reflected light was monitored as a function of the acetone concentration. The sensor response shows a significant change in sensitivity as compared with the POF probe without a graphene coating. The present sensor shows a satisfactory response upon exposure to various concentrations of acetone vapor from 44 ppm to 352 ppm. To the best of our knowledge, the use of graphene film along with POF for the sensing of volatile organic compounds has not previously been reported.