Related Experiment Video
Updated: Aug 9, 2026

Use of Principal Components for Scaling Up Topographic Models to Map Soil Redistribution and Soil Organic Carbon
Published on: October 16, 2018
The "lotus effect" explained: two reasons why two length scales of topography are important
Lichao Gao1, Thomas J McCarthy
1Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Abstract:
Surfaces containing 4 x 8 x 40 microm staggered rhombus posts were hydrophobized using two methods. One, using a dimethyldichlorosilane reaction in the vapor phase, introduces a smooth modified layer, and the other, a solution reaction using methyltrichlorosilane, imparts a second (nanoscopic) length scale of topography. The smooth modified surface exhibits contact angles of thetaA/thetaR = 176 degrees /156 degrees . Arguments are made that the pinning of the receding contact line by the post tops (with thetaA/thetaR = 104 degrees /103 degrees ) is responsible for the hysteresis. The second level of topography raises the contact angles of the post tops and the macroscopic sample to theta(A)/theta(R) = >176 degrees />176 degrees and eliminates hysteresis. The increase in Laplace pressure due to the increase in the advancing contact angle of the post tops is a second reason that two length scales of topography are important.
More Related Videos
08:09Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management
Published on: September 12, 2017
10:30Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations
Published on: September 11, 2016
Related Concept Videos
Topographic Surveying and Contours
Level Curves and Contour Maps
Plotting of Topographic Maps
Methods of Obtaining Topography
Interpretations of Partial Derivatives
Influence of Earth's Curvature and Atmospheric Refraction on Leveling