Optical properties of chain-like soot with water coatings

In a moist atmosphere,the ageing process of aerosol can make the agglomerated soot particles compact,and cause them to be covered by a water coating.Based on the cluster‒cluster aggregation(CCA)algorithm,the models of chain-like soot with water coatings(Models A to E)were generated in this study.The superposition T-matrix method was employed to calculate their optical properties at 337,550,860,and 1060 nm wavelengths,with a focus on the impact of the soot inclusion morphology and water coating.Our results indicate that for particles with a looser soot-inclusion structure,there is a larger difference in the scattering phase function between them and the corresponding particles with a spherical soot core.The largest relative difference reached 51.8%at 337 nm.Impacted by the size parameter,the extinction cross section(Cext),absorption cross section(Cabs),scattering cross section(Csca),and single scattering albedo(SSA)increased as the water coating radius(Rwater)increased and incidence wavelength decreased.The traditional assumption of a spherical soot core can cause the Cext,Cabs,and Csca to be overestimated,and cause the SSA to be underestimated when the incident wavelength is 337 nm.At 1060 nm,the assumption can cause the Cext,Cabs,and Csca to be underestimated,and lead the SSA to be overestimated.When the fractal dimension(Df)of chain-like soot inclusion increased from 1.8 to 2.6,the SSA of the particles with a Rwater of 0.20μm significantly decreased from 0.784 to 0.764 at 1060 nm.Moreover,the thickness of the water coating had a stronger effect on the particles with chain-like soot inclusion at 337 nm than that at 1060 nm.For the 337 nm wavelength,the difference between the Cext and Csca in Model B when Rwater=0.30 and 0.20μm was 0.588 and 0.587μm2,respectively.The differences were only 0.096 and 0.095μm2,respectively,for the 1060 nm wavelength.Based on the results calculated by the superposition T-matrix method,the ratios of P22(Θ)/P11(Θ)for chain-like soot with water coatings are not absolutely equal to 100%.When the Df value of aggregated soot inclusion is a constant,P22(Θ)/P11(Θ)decreased as the volume ratio of soot inclusion to the water droplet increased.Therefore,the ratio of P22(Θ)/P11(Θ)can be potentially used as an optical indicator to describe the morphology of non-spherical and/or inhomogeneous particles(or inclusion)for internal aerosol,fog,or cloud particles.Generally,although the thickness of the water coating,to a large extent,dominates the optical properties of the internal mixtures,the morphology of aggregated soot inclusion is a key factor for causing uncertainties in optical parameters.This is especially so when the volume ratio of the soot inclusion and water droplet is large,and the structure of the soot inclusion is loose.

Water-conducting Characteristics and Micro-dynamic Self-adjusting Behavior of Polyacrylamide/Montinorillonite Coating

A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.

Investigation of Adsorption Rates of Pb, Cd, Cu, Co and Ni to Fresh-water Surface Coatings Developed in Nanhu Lake

The adsorption kinetics of five heavy metals onto the natural surface coatings, which were collected in the Nanhu Lake in Changchun, Jilin Province, China, were investigated for the purpose of giving some explanations for the mechanisms of heavy metal adsorption onto the surface coatings with initial metal ions of 5 μmol/L. The results show that firstly, the adsorption of heavy metals onto the surface coatings follows the first order kinetics; secondly, the double-constant rate equation is suitable to describing the adsorption of heavy metals selected onto the natural aquatic surface coatings, following the order K_ Cu>K_ Pb>K_ Co>K_ Ni>K_ Cd; thirdly, there is a significant correlation between the adsorption rate and the physical and chemical characteristics of heavy metals, such as E 0, Δ_fH 0_m, and Δ_fG 0_m based on the linear regression analysis.

Study on the Rapid Method to Predict Longevity of Controlled Release Fertilizer Coated by Water Soluble Resin

The study discussed the rapid method to test and predict the longevity of controlled release fertilizers （CRFs） coated by water soluble resin by using the short-term leaching under higher temperature. Pure water dissolving incubation and higher temperature leaching were used to study the patterns of the nutrient release of the CRFs. The correlation analysis between the days at 25℃ and the hours at 80℃ of Trincote 1 and Trincote 2 for the same cumulative release rates were conducted. Patterns of cumulative nutrient release curve followed one factor quadratic regression equation at each given temperatures, and each of relative coefficient was bigger than 0.995. As the temperature increased, nutrients release of the CRFs increased. The longevity of resin coated CRFs were predicted by use of both the cumulative nutrients release equation at 80℃ and the regression equation of release time needed for the same cumulative release rates between 25 and 80℃. There were only 0.3-6.9% relative errors between the tested longevity and predicted one. In conclusion, the longevity of resin coated CRFs could be predicted more quickly and precisely by use of the higher temperature short-term leaching method than that of the traditional differential release rate. The longevity of resin coated CRF could be rapidly and precisely predicted in a few hours by application of the higher temperature shortterm leaching method.

Why a mosquito leg possesses superior load-bearing capacity on water:Experimentals

Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force（WSF） that is 23 times their body weight.Aiming at a full understanding of the origins of this extremely large force,in this study,we concentrate on two aspects of it：the intrinsic properties of the leg surface and the active control of the initial stepping angle of the whole leg.Using a measurement system that we developed ourselves,the WSFs for the original leg samples are compared with those whose surface wax and microstructures have been removed and with those of a different stiffness.The results show that leg f exibility plays a dominant role over surface wax and microstructures on the leg surface in creating the supporting force.Moreover,we discuss the dependence relationship between the maximum WSF and the initial stepping angle,which indicates that the mosquito can regulate this angle to increase or decrease the WSF during landing or takeoff.These finding are helpful for uncovering the locomotion mechanism of aquatic insects and for providing inspiration for the design of microfluids miniature boats,biomimetic robots,and microsensors.