Explore the vast range of titles available.

Knowledge of haze particles in background areas of North China is limited, although they have been studied well in urban settings. Atmospheric aerosol particles were collected at a background site in the North China Plain during 16-31 January, 2011. Water soluble inorganic ions of PM2.5 and physicochemical characteristics of individual particles on hazy and clean days were measured by Ion Chromatography （IC） and Transmission Electron Microscopy （TEM）, respectively. Average PM2.5 mass concentration was 50.4±29.9 μg m^-3 with 62.5±26.8 μg m^- 3 on hazy days and 19.9±11.5 μg m^- 3 on clean days. SO4^2-, NO3^-, and NH4^＋ with a combined mass concentration of 19.0±11.5 μg m^-3 accounted for 69.8%-89.4% of the total water soluble inorganic ions. Size distributions of SO4^2- and NH4^＋ showed one unimodal peak at 0.56-1.8μm on hazy days, whereas NO3^- appeared as bimodal peaks at 0.56-1.8 and 5.6-10 μm, respectively. Individual particle analyses showed that the dominant aerosols were a mixture of sulfate, nitrate, and carbonaceous species, which together determine their mixing states. 48-h air mass back trajectories on hazy days suggested that air masses crossed the polluted continental areas （such as Jing-jin-ji region and Shandong province） and entrained ground air pollutants 11-19 hours before reaching the background area. During long-range transport particles undergo ageing and tend to be internally mixed mainly due to condensation in the background atmosphere. Our results suggest that hygroscopic and optical properties of these aerosol particles in the background area differ substantially from those in urban areas.

Aerosol technology provides efficient methods for producing nanoparticles with well-controlled composition and size distribution. This review provides an overview of methods and results obtained by using aerosol technology for producing nanostructures for a variety of applications in semiconductor physics and device technology. Examples are given from: production of metal and metal alloy particles; semiconductor nanoparticles; semiconductor nanowires, grown both in the aerosol phase and on substrates; physics studies based on individual aerosol-generated devices; and large area devices based on aerosol particles.

ABSTRACT During a sea-fog field observation campaign on Donghai Island in the spring of 2011, fog-water, visibility, meteorological elements, and fog droplet spectra were measured. The main cations and anions in 191 fog-water samples were Na＋, NH2, H＋, NO3, C1- and SO] , and the average concentrations of cations and anions were 2630 and 2970 p-eq L 1, respectively. The concentrations of Na＋ and C1- originated from the ocean were high. The enhancement of anthropogenic pollution might have contributed to the high concentration of NH＋, H＋, and NO^-3. The average values ofpH and electrical conductivity （EC） were 3.34 and 505 uS cm-1, respectively, with a negative correlation between them. Cold fronts associated with cyclonic circulations promoted the decline of ion loadings. Air masses from coastal areas had the highest ion loadings, contrary to those from the sea. The ranges of wind speed, wind direction and temperature corresponding to the maximum total ion concentration （TIC） were 3.5-4 m s-1, 79°-90° and 21°C-22°C, respectively. In view of the low correlation coefficients, a new parameter Lr was proposed as a predictive parameter for TIC and the correlation coefficient increased to 0.74. Based on aerosol concentrations during the sea-fog cases in 2010, we confirmed that fog-water chemical composition also depended on the species and sizes of aerosol particles. When a dust storm passed through Donghai Island, the number concentration of large aerosol particles （with diameter 〉 1 p-m） increased. This caused the ratio of CaZ＋/Na＋ in fog-water to increase significantly.

The impact of aerosols on the climate and atmospheric environment depends on the water uptake ability of particles; namely, hygroscopic growth and acti- vation into cloud condensation nuclei （CCN）. The size-resolved activation ratios （SRAR）, characterizing the fraction of aerosol particles that act as CCN at different particle sizes and supersaturations, can be measured using a combination of differential mobility analyzers （DMA） and particle counters. DMA-based measurements are in- fluenced by the multiply charged particles and the quasi-mono-dispersed particles （effect of DMA transfer function） selected for each prescribed particle size. A theoretical study, assuming different particle number size distributions and hygroscopicity of aerosols, is performed to study the effects of the DMA transfer function and multiple charging on the measured SRAR and the derived hygroscopicity. Results show that the raw SRAR can be significantly skewed and hygroscopicity may be highly biased from the true value if the data are not corrected. The effect of the transfer function is relatively small and depends on the sample to sheath flow ratio. Multiply charged particles, however, can lead to large biases of the SRAR. These results emphasize that the inversion algo- rithm, which is used to correct the effects of the DMA transfer function and multiple charging, is necessary for accurate measurement of the SRAR.

The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

The characteristics of aerosol flotation, which include the effect of the concentration and particle size of kerosene aerosol on the molybdenum （Mo） flotation index and the effect of kerosene aerosol dosing method on the kerosene dosage and flotation time, were studied in the flotation of low-grade refractory molybdenum ores using kerosene aerosol. The results revealed that the particle size and concentration of kerosene aerosol had little effect on the Mo grade but had significant effect on the Mo recovery. A smaller particle size and a lower con-centration of kerosene aerosol were beneficial to the Mo aerosol flotation. For the received Mo ore samples, the optimized particle size of kerosene aerosol was 0.3-2 μm and the optimized aerosol concentration was 14 mg/L. The compressed air atomizer had a more uniform dis-tribution of aerosol particles than the ultrasonic atomizer, and the aerosol concentration was controlled easily, so the compressed air atomizer was more suitable for the research of aerosol flotation. Compared with conventional flotation in which kerosene was directly added into the ore pulp, the flotation time was reduced by ~30%, and the dosage was decreased by ~20% in aerosol flotation, while the Mo flotation index was similar.

Insoluble particle concentration in ice cores is commonly analyzed as a proxy for varia- tions in atmospheric mineral dust （aerosol concentration）. However, recent studies have revealed that the mineral dust is not only a constituent of the particles but that biogenic organic particles are also contained. We microscopically analyzed insoluble particles in a shallow ice core drilled on a mountain glacier, the Urumqi Glacier No. 1, in eastern Tienshan, China. We distinguished different morphological particles in the ice core and quantified them separately. Results showed that the insoluble particles in this ice core consisted mainly of mineral particles, amorphous organic particles, pollen, and micro- organisms. Mineral particles were the most dominant, accounting for approximately 67% of total par- ticles, and amorphous organic particles were the second most dominant, accounting for approximately 33% of the total. The annual variation in the particles for the last 11 years differed between mineral and amorphou