Effects of roughness on droplet apparent contact angles on a fiber

This paper reports on our investigation of the effects of surface roughness on the equilibrium shape and apparent contact angles of a droplet deposited on a fiber. In particular, the shape of a droplet on a roughened fiber is studied via the energy minimization method implemented in the surface evolver finite element code. Sinusoidal roughness varying in both the longitudinal and radial directions is considered in the simulations to study the effects of surface roughness on the most stable shape of a droplet on a fiber (corresponding a global minimum energy state). It is found that surface roughness delays droplet shape transition from a symmetric barrel to a clamshell or an asymmetric barrel profile. A phase diagram that includes the effects of fiber roughness on droplet configurations-symmetric barrel, clamshell, and asymmetric barrel-is presented for the first time. It is also found that droplet apparent contact angle tends to decrease on rough fibers. Likewise, roughness tends to increase the force required to detach a droplet from a fiber but the effect diminishes as droplet size increases relative to the size of surface roughness. The results presented in our study have been compared with experimental data or those from prior studies whenever possible, and good agreement has been observed

"The real rights of man". Thomas Spence, Paine and Chartism

A deep engagement with Spence’s ideas can be found in the Chartist movement. In its drive for radical parliamentary reform, we can see the working out of Paineite thinking. And in Chartism’s impulse towards agrarian reform, we can see the working out of Spencean thinking. Uncritical deference to Paine’s memory has often obscured the contribution of others among his contemporaries to radical political thought. In the field of agrarian ideas, it was Spence not Paine whose influence was the more decisive. This is evident even in the writings of Paine’s indefatigable disciple Richard Carlile. Four elements underpinned all Chartist thinking on landed property and they also encapsulated the essence of Spence’s ideas. 1] A fundamental belief that smallholder cultivation maximised the productivity of the soil. 2] Hostility to large holdings of landed property, irrespective of their legal form. 3] A suspicion of central government as a potential owner or manager of the national estate. 4] Land holding was part of a broader assault upon the citadel of economic and political power. This article will now briefly consider each in turn