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Measurements of aerosol chemical and hygroscopic properties and cloud condensation nuclei were carried out as a part of the third Pallas Cloud Experiment. In this study, the aerosol hygroscopicity parameter, κ, was determined using data from instruments operating in the sub-saturated and supersaturated water vapour regimes, as well as from measurements of aerosol chemical composition. During the campaign, κ varied from ~0.01 to ~0.37 as derived by Cloud Condensation Nuclei counter and Hygroscopic Tandem Differential Mobility analyser data, and from ~0.13 to ~0.60 as derived from Aerosol Mass Spectrometer data, the average values being 0.11 and 0.29, respectively. CCN closure calculations showed that the sub-saturated growth factor retrieved CCN concentration is lower than the measured one. Overall, at the Pallas site, aerosol hygroscopicity was size dependent with hygroscopicity increasing with size. Hence, size dependent information on composition is needed to predict CCN concentrations relevant to cloud droplet formation. [ABSTRACT FROM AUTHOR]

Electrical Low Pressure Impactor (ELPI) was used to study the physical phase of fresh secondary-organic-aerosol (SOA) particles formed by the ozonolysis of pure α-pinene in a chamber. The particles bounced from smooth impactor plates towards lower impactor stages, indicating a solid physical state. These particles had a similar bouncing ability as Scots pine-derived particles in previous studies. The measured bounce factor of large particles (diameter > 40 nm) did not significantly change during the particle growth, indicating no changes in the particle solidity. For the smallest particles, the calculated bounce factor increased as the particles grew. The smallest particles were less solid (i.e. having lower viscosity) than the larger ones. The maximum value of the bounce factor decreased for consequent impactor stages. According to a simplified model, this can be explained by a combination of bounce probability and charge transfer between the particles and the impactor surface if at least 50% particles are bouncing. [ABSTRACT FROM AUTHOR]

A laser aerosol time-of-flight mass spectrometry (ATOFMS) that can be used for real-time measurement of the size and composition of individual aerosol particles has been designed and manufactured in our laboratory. Particles are introduced into the instrument through a particle beam interface, sized by measuring the delay time between two scattering lasers, and compositionally analyzed using a laser desorption/ionization linear-time-of-flight mass spectrometry. Secondary organic aerosol particles from the photooxidation of toluene in the CH3ONO/NO/air mixture were generated in a home-made smog chamber and measured using it. Experimental results showed that the individual aerosol particles from photooxidation of toluene can be measured in real-time by this instrument. This unique capability is impossible in off-line methods such as chromatography and chemical method. [ABSTRACT FROM AUTHOR]

CuS nanoflowers were loaded on anatase TiO2/polyvinylidene fluoride (PVDF) fibers by hydrothermal treated electrospun tetrabutyl orthotitanate (TBOT)/PVDF fibers at low temperature. The results indicated that the amount of copper source and sulfur source determined the crystallization and morphology of the resultant products. It was found that the composite of CuS narrowed the band gap energy of TiO2 and enhanced the separation efficiency of the photogenerated electron-hole pairs of TiO2. The photocatalytic reaction rate of CuS/TiO2/PVDF fibers to rhodamine B was 3 times higher than that of TiO2/PVDF fibers under visible light irradiation. Besides, owing to the preparation process was carried out at low temperature, the flexibility of CuS/TiO2/PVDF fibers was ensured. In addition, the self-cleaning performance of the dye droplets on the resultant product surface was demonstrated under visible light. Meanwhile, the resultant product can automatically remove dust on the surface of the material under the rolling condition of droplets due to its hydrophobicity. Therefore, the as-prepared CuS/TiO2/PVDF fibers can not only degrade the contaminated compounds, but also depress the maintenance cost owing to its self-cleaning performance, which means a very practical application prospect. [ABSTRACT FROM AUTHOR]

The dissolution of transition-metal (TM) cations into a liquid electrolyte from cathode material, such as Mn ion dissolution from LiMn 2 O 4 (LMO), is detrimental to the cycling performance of Li-ion batteries (LIBs). Though much attention has been paid to this issue, the behavior of Mn dissolution has not been clearly revealed. In this work, by using a refined in situ ultraviolet-visible (UV-vis) spectroscopy technique, we monitored the concentration changes of dissolved Mn ions in liquid electrolyte from LMO at different state of charge (SOC), confirming the maximum dissolution concentration and rate at 4.3 V charged state and Mn 2+ as the main species in the electrolyte. Through ab initio molecular dynamics (AIMD) simulations, we revealed that the Mn dissolution process is highly related to surface structure evolution, solvent decomposition, and lithium salt. These results will contribute to understanding TM dissolution mechanisms at working conditions as well as the design of stable cathodes.