The 'Leaky Slit' Model

One of my colleagues made a video.  Check it out....

This instrument the DeltaPi-4 can measure the dynamic surface tension of a number of different films.  You can then inject drugs, surfactants, proteins or, as Rohit did peptides underneath the surface.  The peptide can change the surface tension of the membrane to give a potential understanding of the mechanism of action.  Here they used a phermone peptide from bacteria.  They saw that it behaves in a line in the planar bilayer.  You can see it in the paper but it is kinda like the columns being aligned at the Acropolis in Greece except with less space.  This alignment shows the mechanism.  This peptide might destroy other bacteria henceforth the name: antimicrobial peptide.  They call it by a provocative name 'The Leaky Slit' model.  Who said science is not fun?

Bubble Fest? Nobody told me.

There is no better way to learn about surface tension and have fun on spring day then blowing a bubble.  Bubble are beautiful, dynamic, different and transient.  At the Discovery Science Center in Orange County California decided to make this into an event.  They have actually done this for 15 years prior.  Nobody told me?

The bubblefest officially happens at the Discovery Science Center March 31 - April 22, 2012.  It is designed to help visitors appreciate and understand the 'scientific principles and mathematics of bubbles', and to let them explore the world of bubbles in a fun, hands-on environment.'  The guests can create their own bubbles to learn about math and science principles like surface tension, elasticity, air pressure, and geometry.

At the 16th Bubblefest it will be the most impressive.  They are even making a giant bubble so you could be like a boy in a bubble.  The best part about it is they hired a curator to do this festival.  Deni Yang makes bubbles for a living.  Really, check out his site: http://bubbleart.com/  Actually this guys is seriously nuts about bubbles and has even ranked in the Guinness World Record #1 Berlin, Germany November 1991 for  The Biggest Spherical Bubble 2,3m (7.45f) In Circumference.  Actually he has 15 other world records.   He tours, he makes toys and he makes bubbles. Kinda awesome.


Check out his video here:

Bubblefest should happen all over the world though and not just in California.  So during March 31st- April 22nd go outside.  Blow some bubbles.  (More about bubble science in another post). 

Q: What is the best way scientists can make more science?

A: Have kids.

There is no doubt that growing up in a house that teaches science you are likely to have children that are also interested in asking questions.  That is what Andrey Sushko's (17 years old) family was like. The progeny of scientists. The wild type control perhaps started asking questions like: 'I wonder if I can make a motor powered by surface tension?' or 'what kind of superhydrophobic substance could be used?' or 'what could a really really small motor be used for?' or 'why the hell does my model boats keep getting stuck on the edge of the tub?'

These kinds of questions were asked, answered and prototyped into an actual motor that was entered into the National Science Talent Search sponsored by Intel. After years of fabricating model boats (one that even got into the Guinness Book of World Records for the smallest radio-controlled sailing yacht) Andrey made a really small motor.  The motor uses the surface tension of water to turn the shaft.  At only 7 mm in diameter the tiny shaft is coated with hydrophobic coating.  This coating can translate the curvature of water into rotation of the shaft.  This then can make a micro-mechanical device that increases its efficiency with miniaturization. 



This was also shown here.




No doubt he watched Almost Live and Bill Nye the Science guy in his native Washington State (see the boat at 4 minutes). 

DuNuoy Padday Tensiometers: 5 Awesomething Things you Should Know

Penetrating one substance at a time

There are many different types of tensiometers on the market.  A tensiometer measures the surface tension of water either statically or dynamically.  It can be measured with mechanically, optically or experimentally measuring different volumes.  Mechanically tensiometers like DuNuoy ring, and DuNuoy Padday rod measure the force on the surface of the water with a probe and attached to a balance.  Optical tensiometers like contact angle or pendant drop calculate the surface tension after taking pictures of the drop size.  Experimentally using flow and different pressures a bubble pressure tensiomer or stagalometers can more or less measure the surface tension of liquids.  See all the different ways of measuring here.

Five awesome things you should know:

1) DuNuoy Padday made by this guy from England in the 1960's and utilized by currently only one company in Finland.  So if you like things English: football, salt and vinegar chips and the Queen or Finnish things: Nokia, Saunas and blondes then you will like their tensiometers. 

2) The minimum volume for measuring using something like a Delta-8 instrument for a microplate is 50 microliters.  That is 1/20000 L of of the beer I will drink tonight (I will only have a pint).  This is even less than what you can measure optically or experimentally.  A normal DuNuoy tensiometer will not even wet the platinum ring with that volume.  Drug, cosmetic and home care companies can use this technology for fast screening of compounds and surfactants for formulations.  Lower volume + less money spent = innovation.


3) No platinum ring.  Platinum is a freaking expensive material (twice the price of gold about 20 dollars a gram).  Why anyone would entrust university students with such a sensitive ring to measure surface tension?  These students are are normally hung over from partying  (amount of beer they drink is multiplied by a factor of 5 in the second point).  The Du Nuoy Padday method utilizes a rod that is difficult to bend and easy to install.  So one can get far more use out of it.  This eliminates the possibility of platinum also being used as a catalyst in Fab labs. 



4) NASA uses these instruments.  What that you say?  NASA.  Yeah NASA.  If a debunk space agency that sent a man to the moon, built multiple rocketships and an international space station (well the good part of it anyway) uses these types of tensiometers then well just about anybody should use these.

5) The method are used for more than just measuring surface tension of aqeous material.  They can be used to measure the surfaces of tissues.  Paul Janmey from University of Pennsylvania does just that.  Different cell types respond to different kinds of surface tension stress.  It might have help understand better embryology from renowned Princeton biology Malcolm Steinberg who recently died.  He stated that ' certain tissues behave like liquids over long timescales with a characteristic surface tension that determines the spatial configuration of interacting tissues and contributes to their arrangement during embryo development..'

I want this job: 5 secrets found behind champagne

Opening the champagne to celebrate occasions like a wedding, a graduation, a job promotion or the weekend is always awesome.  You hear that 'POP' and then the party suddenly magically begins.  What do we really know about champagne.  It took some researchers, a high speed camera and many many bottles of champagne to find out.  (I wonder what the grant proposal would have looked like for this research.)

Gerard Liger Belair studies the bubbles in Champagne

1) the surface tension in champagne bubbles use champagne bubble with a radius of  R ~ 0.1 mm, and a pressure of P ~ 1000 Pa ~ 10-2 atm ~ 50 mN/m.  In comparison a soap bubble is soap bubble: R ~ 5 cm, surface tension~ 35 mN/m, P ~ 3 Pa ~ 3.10-5 atm.  Laplace Law calculates these for a bubble. 
See a presentation by the group that studied the champagne.  http://www.pmmh.espci.fr/~jbico/chapter1.pdf

2) yeast eats sugar and excretes alcohol and carbon dioxide (CO2).  This fermentation process was developed by the Benedictine monk from the 17th century Dom Pierre Perignon (all the good things religion has brought).  Before sealing the champagne bottle the CO2 is dissolved in the wine.  Champagne wines are supersaturated with the dissolved gas molecules, which form together with the ethanol during the second fermentation process, or the 'prise de mousse'. The bottles are sealed and stored in cool cellars to allow the CO2 molecules to gradually dissolve.

3) How does one person study champagne bubbles?  They use a high speed camera to take snap shots of at each stage in the bubbles short life to explain the forces they play.  Scientist Gérard Liger-Belair of the University of Reims did this for the journey of a trillion microscopic bubbles.

4) What did they find?  In a 75 cl bottle of champagne (costing around 40 euros minimum) it contains about 9 grams of dissolved CO2.  Each bubble has an average size of 0.5 mm.  The number of bubbles released in one bottle is about 1 million.  Nucleation from impurities inside the champagne glass (dirt, soap residue, cracks for example) birth this process.  The bubbles then rise to the top of the glass at the water interface and burst on the surface. 

5) What can we do with this?  Besides getting the researchers drunk we can fine tune the champagne production and calculate the amount of fermentation of sugar needed to produce enough bubbles for the champagne.  The amount of dissolved CO2 is important 'as it affects the bubble count in the glass, the growth rate of rising bubbles, the mouth feel of collapsing bubbles and aromatic sense it creates, or its so-called bouquet.'   The three grape varieties used Chardonnay, Pinot Munier and Pinot Noir all play a part in how good the champagne is and is up to the growers and blenders to see how this mix, the growing patterns around the Champagne region of France get impart its taste.

Study Shows No Connection Between Surface Tension on Solids and Energy

Study Shows No Connection Between Surface Tension on Solids and Energy.

The most amazing thing is that this happened right next door and has been broadcast around the world. The old Shuttleworth equation thought that there is a connection between the liquid surface tension and the surface energy on the solid. However, VTT scientists have disproved this showing that there is a nonexistence of excess surface tension described by the Shuttleworth equation, and that the existence of surface stress on a solid material is required by molecular dynamics only at the surface layer. This creates a new definition of surface tension on solids.