Re: [Aroid-l] lotus effect with Colocasia fallax

From: =?iso-8859-1?B?ZGF2aWQgYnL2ZGVyYmF1ZXI=?= <david_dav44 at hotmail.com> on 2011.01.18 at 08:17:38(21763) Hi Ted, As far as I know it was the Barthlott-group in Germany who studied the Pistia-leave under SEM. They showed that the hairs are coated with wax... David HTML +More > Date: Sun, 16 Jan 2011 16:09:12 -0500 > From: oppenhauser2001@gmail.com > To: aroid-l@www.gizmoworks.com > Subject: Re: [Aroid-l] lotus effect with Colocasia fallax > > David, > > I have no idea whether or not individual Pistia hairs are coated with > some form of wax or whether the wetting by water of an individual hair > is simply poor enough to provide a bridge for the droplet surface over > to the next surface hair, which bridging prevents wicking of the water > down into the hairy structure. > > This would be a good research topic: Dry some Pistia leaves and see > what is extracted (meaning dissolved by some liquid, ordinarily > followed by gentle drying to investigate the residual - Steve Lucas > was right to insist on technical terms being defined) by solvent > (hexane or toluene would be good solvent candidates for wax) and if it > is indeed a waxy substance. If no one has done this I'll do it myself > and report back to this forum. > > Another thing that might be of interest to aroiders is that the net > result of Pistia hydrophobicity (which merely means its reluctance to > be wetted by water, typically observed as a tendency for water on a > hydrophobic surface to "bead up" into discrete droplets) is the > extreme buoyancy of the species. Try to submerge one of these plants > and it's almost like you are trying to submerge an air bubble. It is > curious to me how insubstantial a Pistia leaf is. It looks big, but > when compacted and dried there is almost nothing left. Much of the > apparent volume is simply air. > > Ted Held > Detroit. > > On Thu, Jan 13, 2011 at 7:53 AM, david bröderbauer > <david_dav44@hotmail.com> wrote: > > Hi Ted, > > > > Pistia is in fact a very beautiful example for a water-repellent surface. It > > has to be kept in mind - as you mention - that it generates this > > superhydrophobic effect with hairs (not with papillate cells like in Nelumbo > > or Colocasia) that are covered with wax. So, the term 'lotus-effect' > > describes the syndrom of superhydrophobicity (which means that the contact > > angle of a water droplet is at least 150°), but there are different > > structures within the Araceae and other plant families, that produce this > > effect. > > > > David Broederbauer > > > >> Date: Wed, 12 Jan 2011 13:04:17 -0500 > >> From: oppenhauser2001@gmail.com > >> To: aroid-l@www.gizmoworks.com > >> Subject: Re: [Aroid-l] lotus effect with Colocasia fallax > >> > >> Geneviève, > >> > >> The lotus effect is quite common in my experience. It has been getting > >> a lot of attention in the popular press lately and there are a number > >> of academic studies of the phenomenon using nano materials. A Google > >> search will turn up many hits. > >> > >> One of the best displays can be seen on the humble aroid Pistia. > >> Leaves of Pistia will support quite a large water droplet with no > >> wetting of the leaf surface that supports the hairs. > >> > >> Ted Held. > >> Detroit > >> > >> 2011/1/11 Geneviève Ferry <jpcferry2@wanadoo.fr>: > >> > Dear aroiders , > >> > > >> > Today, three students came looking leaves Colocasia fallax to understand > >> > the > >> > phenomenon of superhydrobicity (lotus effect). > >> > Do you have information on this phenomenon? > >> > (Experience, etc. ....) > >> > > >> > Thank you for your help. > >> > > >> > Best wishes , > >> > > >> > Geneviève Ferry > >> > _______________________________________________ > >> > Aroid-L mailing list > >> > Aroid-L@www.gizmoworks.com > >> > http://www.gizmoworks.com/mailman/listinfo/aroid-l > >> > > >> > > >> _______________________________________________ > >> Aroid-L mailing list > >> Aroid-L@www.gizmoworks.com > >> http://www.gizmoworks.com/mailman/listinfo/aroid-l > > > > _______________________________________________ > > Aroid-L mailing list > > Aroid-L@www.gizmoworks.com > > http://www.gizmoworks.com/mailman/listinfo/aroid-l > > > > > _______________________________________________ > Aroid-L mailing list > Aroid-L@www.gizmoworks.com > http://www.gizmoworks.com/mailman/listinfo/aroid-l --_aa692191-b8cf-4caa-b1b8-768e807972f4_-- --=============="25912303437619595=

Note: this is a very old post, so no reply function is available.