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In this study, 8% fenpropathrin nanoemulsion was prepared by phase inversion temperature (PIT) method with 8% xylene and 4% solvent oil 150# as the solvent. The characteristics of this nanoemulsion were tested and compared with emulsifiable concentrate (EC). The size of 8% fenpropathrin nanoemulsion was 62.99nm, which was much smaller than that of 20% fenpropathrin EC (459.00nm). The mixed surfactants were added in fenpropathrin nanoemulsion with DBS-Ca:LAE at 1:2 to increase the stability, and the concentration of the mixed surfactants at 10wt.% showed the highest stability and much better synergism and surface activity. The absolute zeta potential of fenpropathrin nanoemulsion was much higher than that of EC, which can effectively prevent the cohesion between particles. Field control test also revealed that the 200mg/L, 100mg/L and 50mg/L fenpropathrin nanoemulsion had higher efficacy than 100mg/L fenpropathrin EC (contrast pesticide) in 4th, 7th, 15th days, respectively. In conclusion, nanoemulsion has a great application prospective in the future.

In this report, the general validity of the Einstein viscosity relation, ${\eta }_r=1+2.5\phi$, $\phi <0.02({\eta }_r={\eta }_s∕{\eta }_0$, ratio of solution to solvent viscosity), is examined in nanofluids where monodisperse spherical nanoparticles (polystyrene latex spheres) of size 50–400nm were dispersed in water at room temperature, 25${}^{\circ }$C. In addition to viscosity, we also measured contact angle, $\theta$, and surface free-energy, $U$, as function of particle concentration and observed that the universal relation $X_r=1+X\phi$, $\phi <0.02$, remained valid, where $X_r$ may be relative viscosity, contact angle or surface free-energy and $X$ is a shape-dependent constant and is 2.5 in the Einstein limit. Thus, the Einstein relation has a wider validity than is generally thought encompassing both bulk and surface properties of nanofluids. Furthermore, we extend the study to establish an empirical relation between intrinsic viscosity [$\eta$] and Huggins interaction parameter $k_H$, with particle size $D$, which obeyed: $[\eta ]$ or $k_H=a+\frac{b}{D}+\frac{c}{D^2}$, where $D$ is in nm, [$\eta$] is in cc/g, $k_H$ is in (g/cc)² and $a$, $b$ and $c$ are constants of particle size. Identical expressions could be established for contact angle and surface free energy. These remarkable observations have not been reported hitherto.