A liquid bridge model for spherical particles applicable to asymmetric configurations

Modeling and Analysis of the Capillary Force for Interactions of Different Tip/Substrate in AFM Based on the Energy Method

This paper presents a simple and robust model to describe the wet adhesion of the AFM tip and substrate joined by a liquid bridge. The effects of contact angles, wetting circle radius, the volume of a liquid bridge, the gap between the AFM tip and substrate, environmental humidity, and tip geometry on the capillary force are studied. To model capillary forces, while a circular approximation for the meniscus of the bridge is assumed, the combination of the capillary adhesion due to the pressure difference across the free surface and the vertical component of the surface tension forces acting tangentially to the interface along the contact line is utilized. Finally, the validity of the proposed theoretical model is verified using numerical analysis and available experimental measurements. The results of this study can provide a basis to model the hydrophobic and hydrophilic tip/surfaces and study their effect on adhesion force between the AFM tip and the substrate.

Water Polishing improved controlled-release characteristics and fertilizer efficiency of castor oil-based polyurethane coated diammonium phosphate

The production cost of controlled-release fertilizers is an important factoring limiting their applications. To reduce the coating cost of diammonium phosphate (DAP) and improve its nutrition release characteristics, the fertilizer cores were modified by water polishing with three dosages at 1, 2, and 3%. The effects of modification were evaluated in terms of particle hardness, size distribution, angle of repose and specific surface area. Castor oil-based polyurethane was used as coating material for fertilizer performance evaluation. A pot experiment was conducted to verify the fertilizer efficiency of coated diammonium phosphate (CDAP) with maize. The results showed that polishing with 2% water reduced the angle of repose by 2.48-10.57% and specific surface area by 5.70-48.76%, making it more suitable for coating. The nutrient release period of CDAP was significantly prolonged by 5.36 times. Soil available phosphorous, enzyme activities, maize grain yield, and phosphorous use efficiency were all improved through the blending application of coated and normal phosphate fertilizer. This study demonstrated that water-based surface modification is a low-cost and effective method for improvement and promotion of controlled release P fertilizers.