This study was part of the international field measurement Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006). We investigated a new particle formation event in a highly polluted air mass at a regional site south of the megacity Beijing and its impact on the abundance and properties of cloud condensation nuclei (CCN). During the 1-month observation, particle nucleation followed by significant particle growth on a regional scale was observed frequently (similar to 30%), and we chose 23 August 2006 as a representative case study. Secondary aerosol mass was produced continuously, with sulfate, ammonium, and organics as major components. The aerosol mass growth rate was on average 19 mu g m(-3) h(-1) during the late hours of the day. This growth rate was observed several times during the 1-month intensive measurements. The nucleation mode grew very quickly into the size range of CCN, and the CCN size distribution was dominated by the growing nucleation mode ( up to 80% of the total CCN number concentration) and not as usual by the accumulation mode. At water vapor supersaturations of 0.07-0.86%, the CCN number concentrations reached maximum values of 4000-19,000 cm(-3) only 6-14 h after the nucleation event. During particle formation and growth, the effective hygroscopicity parameter kappa increased from about 0.1-0.3 to 0.35-0.5 for particles with diameters of 40-90 nm, but it remained nearly constant at similar to 0.45 for particles with diameters of similar to 190 nm. This result is consistent with aerosol chemical composition data, showing a pronounced increase of sulfate.
We propose a refractive index sensor based on the interference of two surface-plasmon waves on both surfaces of a gold film with a two-slit structure. The phase of the interference was solved, and the dispersion relation of the real part of Au dielectric function was considered. The sensor was performed with NaCl-H(2)O solutions of different concentrations and exhibited a linear response and a high sensitivity of 4547 nm/RIU (refractive index unit) to the refractive index change. (c) 2009 Optical Society of America
Biological contact oxidation technology was used to remediate the polluted river water in Hanyang, China. The purification effect of the polluted river water in three simulated rivers was investigated using two different carriers, i.e., AquaMats made in USA and semi flexible supports made in China. The results showed that when the hydraulic loading rate increased, purification effect in terms of CODMn decreased. Moreover, the removal efficiency of total nitrogen (TN) increased when AquaMats support was used, however it decreased when semi flexible support was used, in comparison with the control experiment. The removal ability of total phosphorus (TP) was strengthened by using different carriers.
Biological contact oxidation technology was used to remediate the polluted river water in Hanyang, China. The purification effect of the polluted river water in three simulated rivers was investigated using two different carriers, i.e., AquaMats made in USA and semi flexible supports made in China. The results showed that when the hydraulic loading rate increased, purification effect in terms of COD(Mn) decreased. Moreover, the removal efficiency of total nitrogen (TN) increased when AquaMats support was used, however it decreased when semi flexible support was used, in comparison with the control experiment. The removal ability of total phosphorus (TP) was strengthened by using different carriers.
Using coplanar waveguide (CPW) to construct left-handed(LH) transmission line is more effective method than microstrip line. In this paper, a new type of LH transmission-line is proposed. It is composed with parallel embedded inductive and serial interdigital capacitor. Through extracting ß parameter of CPW transmission line, the region of LH transmission-line is obtained from 6 GHz to 14 GHz. The effective bandwidth is about 52% in 7.5 GHz-12.7 GHz. The backward-wave characteristic is validated by full-wave simulation.
To further understand and improve air quality for the 2008 Beijing Olympic Games, the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) were carried out in an urban and a suburban area from 10 August to 12 September 2006. As a part of an intensive series of measurements, the optical and physical properties of the aerosol were monitored together with identification of the chemical species involved. A method to calculate the hygroscopic factor for aerosol scattering f(RH), defined as the ratio of the aerosol scattering coefficient at given relative humidity (RH) to that at 35% RH, is proposed on the basis of the optical parameters. Over the course of the study f(80%) = 1.63 +/- 0.19. The observation that the molar ratio of NH4+ to (2*SO42- plus NO3-) was very close to 1 implies that the chemical form of the sulfate aerosol may be ammonium sulfate (NH4)(2)SO4 and that nitrate possibly existed as NH4NO3. On the basis of the measurements of size-resolved chemistry, RH, and published functional relationships between the chemical composition and water uptake, the aerosol scattering coefficients could be calculated by the Mie theory for the major particle species (ammonium sulfate, ammonium nitrate, sodium chloride, particulate organic matter, elemental carbon, and residual material). This retrieval method synthesizes the high temporal resolution of mass concentration measurements and low temporal resolution size distribution for water soluble ionic components and carbonaceous aerosols. A local closure experiment is obtained by comparing the measured f(RH) with model calculations using aerosol chemical composition and chemical thermodynamics. Results from the closure study show that the measured and the predicted values of f(RH) agree within measurement uncertainties.
To further understand and improve air quality for the 2008 Beijing Olympic Games, the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) were carried out in an urban and a suburban area from 10 August to 12 September 2006. As a part of an intensive series of measurements, the optical and physical properties of the aerosol were monitored together with identification of the chemical species involved. A method to calculate the hygroscopic factor for aerosol scattering f(RH), defined as the ratio of the aerosol scattering coefficient at given relative humidity (RH) to that at 35% RH, is proposed on the basis of the optical parameters. Over the course of the study f(80%) = 1.63 +/- 0.19. The observation that the molar ratio of NH4+ to (2*SO42- plus NO3-) was very close to 1 implies that the chemical form of the sulfate aerosol may be ammonium sulfate (NH4)(2)SO4 and that nitrate possibly existed as NH4NO3. On the basis of the measurements of size-resolved chemistry, RH, and published functional relationships between the chemical composition and water uptake, the aerosol scattering coefficients could be calculated by the Mie theory for the major particle species (ammonium sulfate, ammonium nitrate, sodium chloride, particulate organic matter, elemental carbon, and residual material). This retrieval method synthesizes the high temporal resolution of mass concentration measurements and low temporal resolution size distribution for water soluble ionic components and carbonaceous aerosols. A local closure experiment is obtained by comparing the measured f(RH) with model calculations using aerosol chemical composition and chemical thermodynamics. Results from the closure study show that the measured and the predicted values of f(RH) agree within measurement uncertainties.
To further understand and improve air quality for the 2008 Beijing Olympic Games, the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) were carried out in an urban and a suburban area from 10 August to 12 September 2006. As a part of an intensive series of measurements, the optical and physical properties of the aerosol were monitored together with identification of the chemical species involved. A method to calculate the hygroscopic factor for aerosol scattering f(RH), defined as the ratio of the aerosol scattering coefficient at given relative humidity (RH) to that at 35% RH, is proposed on the basis of the optical parameters. Over the course of the study f(80%) = 1.63 +/- 0.19. The observation that the molar ratio of NH4+ to (2*SO42- plus NO3-) was very close to 1 implies that the chemical form of the sulfate aerosol may be ammonium sulfate (NH4)(2)SO4 and that nitrate possibly existed as NH4NO3. On the basis of the measurements of size-resolved chemistry, RH, and published functional relationships between the chemical composition and water uptake, the aerosol scattering coefficients could be calculated by the Mie theory for the major particle species (ammonium sulfate, ammonium nitrate, sodium chloride, particulate organic matter, elemental carbon, and residual material). This retrieval method synthesizes the high temporal resolution of mass concentration measurements and low temporal resolution size distribution for water soluble ionic components and carbonaceous aerosols. A local closure experiment is obtained by comparing the measured f(RH) with model calculations using aerosol chemical composition and chemical thermodynamics. Results from the closure study show that the measured and the predicted values of f(RH) agree within measurement uncertainties.
