We show a geometric method to compute the Van der Waals factor 1/r7 between the assemblies of amino acid molecules of the subunits of acetyl choline (abbreviated by Ach: a kind of neuro chemical transmitter) sensitive channel on the post synaptic membrane of the neural system. We induced a analytical geometric formula for the distances between helically arranged ten assemblies of the point amino acid molecules on two interacting membrane perforating poly peptides, M2 helices during channel opening deformation. Detailed geometric parameters have been utilized from reported biophysical measurements. The computed Van der Waals factor decreased rapidly as the slope of the first M2 helix along the central axis of the channel pore has increased. The Van der Waals factor also decreased by an increase in rising angle of the helically arranged amino acids on the M2 helices. The Van der Waals factor increased significantly as the first M2 helix has rotated around the central axis of the channel pore to take an opening position. We discussed the time dependent molecular structural changes of the Ach sensitive channel opening in conjunction with the Allosteric properties of the bio molecules. The molecular mechanism of Ach sensitive channel opening in terms of the Allosteric property may derive from the characteristic helical constitutional nature of the membrane perforating part (M2 helix) of the subunits of the channel molecule.

We have investigated the relationship between particle removal efficiency and etched depth in SC-1 solution (the mixture composed of ammonium hydroxide, hydrogen peroxide and DI water) for Si wafers. The Si etching rate increases with increasing NH4OH (ammonium hydroxide) concentration. The particle removal efficiency depends on the etched Si depth, and is independent of NH4OH concentration. The minimum required Si etching depth to get over 95% particle removal efficiency is 4 nm. Particles on the Si wafers exponentially decrease with increasing the etched Si depth. However the particle removal efficiency is not affected by particle size ranging from 0.2 to 0.5 µm. The particle removal mechanism on the Si wafers in SC-1 solution is dominated by the lift-off of particles due to Si undercutting and redeposition of the removed particle.