Liu Tianqing

Ultrasound enhancement of biocide efficiency

In order to take account of the likely increase in costs of biocides in the light of increasing legislation and concern for the environment, there is a need to maximise the efficiency of biocides for the control of biofouling. The use of ultrasound in conjunction with biocides offers such an opportunity. Tests have been carried out using ultrasound generated at 20 kHz in conjunction with the oxidising biocide ozone, in a laboratory pilot plant, to investigate the effects of mutuality. The preliminary results reported in this paper suggest that the combined effect of ultrasound and the biocide is better than either separately employed. Clearly substantially more work is required in order to maximise effectiveness for minimum cost.

Properties and Spreading Kinetics of Water-Based Cypermethrin Microemulsions

Water-based cypermethrin microemulsions were prepared by adding oil to emulsified water, with ethyl butyrate as the solvent,TritonX-100(TX-100) and sodium dodecyl benzene sulfonate(SDBS) as surfactants,and n-butyl alcohol(n-C_4H_9OH) as a co-surfactant.The structure and properties of the microemulsions were investigated by determining the phase diagram,and using negative-staining transmission electron microscopy,and conductivity,surface tension,dynamic light scattering,and contact angle measurements.The spreading kinetics of the microemulsions on the leaf surface of Youngfu wheat was also studied.The results showed that the cypermethrin microemulsions followed the oil-in-water model,and had a strong solubilizing effect on cypermethrin.The microemulsions showed a low contact angle,and low surface tension,and the droplet radius was about 45 nm.The kinetics for the spreading of the microemulsions on the leaf surface of Youngfu wheat fitted a second-order kinetic equation.The kinetic rate constants were 0.1090(°)~(-1)·min~(-1)(20℃) and 0.1572(°)~(-1)·min~(-1)(30℃),and the activation energy was 27.03 kJ·mol~(-1).

Measurement of Wenzel roughness factor by laser scanning confocal microscopy

The Wenzel roughness factor r is one of the most important parameters to characterize a super-hydrophobic surface. In this study, in order to prove the feasibility of using laser scanning confocal microscopy (LSCM) to measure the roughness factor r, the detected r values by LSCM on texture-regular surfaces were compared with those calculated firstly, and then the r values measured by LSCM for texture-irregular rough surfaces were compared with those measured by AFM. The results show that the r values of texture-regular surfaces measured by LSCM are close to those calculated, and the LSCM measured r values of texture-irregular surfaces with small roughness are consistent with those measured by AFM. Moreover, the r values of texture-irregular surfaces with large roughness can only be measured by LSCM, the detected r values of three such super-hydrophobic surfaces are 2.13 ± 0.01, 2.12 ± 0.01 and 2.13 ± 0.02, respectively. In addition, it is proved that the r measured by LSCM as a line length ratio is equal to the original definition of roughness factor as the ratio of actual area of solid surface to the horizontal projected area. Consequently, it is reliable to measure the r value of a texture-irregular surface with large roughness in micro or submicro scale by LSCM.