Wednesday, 16 November 2011

How to superhydrophobic surfaces can help you prevent mustard stains.erhydrophobic substances.

Betty White eating a tubesteak without ketchup or mustard.

 I was eating a hot dog in Seattle an hour before I was supposed to meet with a long time friend whom I was visiting.  I bought the meat wrapped in a bun from the vendor, piled some onions, relish, French's mustard ontop before unleashing a fury frenzy of eating that I had not had after living in a civilized place like Helsinki.  People eat a little bit more refined.  I stood on the street corner and started devouring it like a dog that had not eaten in a couple of days.

It was one of those awesome tube steak hotdogs where you crunch down through a harder skin then some juices start flowing out from the soft meat underneath.  The ketchup and mustard started mixing with the juices making an unsightly mix of yellow and red colloids oozing out of it.  I did not really notice these non-newtonian fluids flowing out of the hotdog bun until it was too late.  Red and yellow with some specs of brown hit the white shirt I had just purchased the day before at Nordström Rack.  (I know to clean this a specific detergent may need to be formulated). 

'Shoot.  Non-newtonian fluids with a specific surface tension with a peculiar contact angle embedding on my new cotton on my shirt!'  I yelled out sparking peculiar reactions from the homeless person standing a yard (we are in America after all) away.  Possibly he was a laid off employee from a cleaning conglomerate because his reply was 'You should have used a superhydrophobic substance to spray on top of it.'

'By golly,' I thought to myself,  'He was right'.  It took a little bit of searching to find that a new silicon-based sprayable coating makes clothing completely waterproof.  NeverWet, developed by Ross Nanotechnology & its key scientist Vinod Sikka, allow liquids and heavy oils to slide off clothing, machinery and electronics.  Water has a surface tension of 72 dynes allowing it spread and with its specific charge properties interact with different materials. Upon application, the superhydrophobic silicon-based coating creates a 160 to 175 degree contact angle (even the lotus plant can have a contact angle of 147 degrees so this is never wet is unreal).  This superhydrophobic silicon based coating makes it nearly impervious for liquids to gain a foothold on clothing like my white shirt.

The same company also submerged an iphone in water for an hour without a failure.  It usually fails in about a minute.  The company could make a lot of money from people like me if they get a foothold in this competitive market.  I would buy it because plan on still eating tubesteaks with a lot of mustard and ketchup.

Tuesday, 8 November 2011

Surface Tension makes Lava lamps

When I think of stuff from the early 80's I think of Star Wars figurines and Laval lamps. Those lamps that you turn on and then turn the lights out sit in your bubble chair and watch in amazement. This was before internet, before cell phones and before good tv like Lost. This is what people did. They watched lava lamps. Granted in some cases the people might have been on drugs but that is what people did they watched lava lamps. Lava lamps are called so because the makers thought the material represented the balsatic smooth unbroken Pahoehoe lava from Hawaii.
Briton Edward Craven-Walker (WWII pilot, inventor and later nudist genre director) invented the lava lamp in 1960 and marketed it quickly after that as a display device. It was originally modeled after something he saw in a pub. What he saw was a jar with two immiscible liquids in them at a pub and decided to build his own (see link diy lavalamp). He went home and used a tall juice container of tapered glass to build his own. On the bottom of the lavalamp a standard bulb or halogen The lamp which heats the glass bottle attached. Inside Craven-Walker experimented with a number of solutions but found that a translucent mix of mineral oil, paraffin wax and carbon tetrachloried would achieve the desired effect when placed in an aqueous medium.

When looking at a lavalamp you notice the floating blobs that change after it heats up. You will see that the wax is more dense than water and float on top of the water at any temperature and when heated it expands, becomes less dense than that of water as well as more fluid. On the other hand the carbon tetrachloride is heavier than water but when heated the density is just slightly above that of water. The blobs move because they got to the top of the tapered glass and cool then go back down to the incandescent light bulb to get heated again. A wire coil in the base of the bottle acts as a surface tension breaker to recombine wax after it descends.
The lavalamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle containing water and a transparent, translucent or opaque mix of mineral oil, paraffin wax and carbon tetrachloride.[1] The water and/or mineral oil can be colored with dyes. The density of common wax is much lower than that of water and would float on top under any temperature. However, the carbon tetrachloride is heavier than water (also nonflammable and miscible with wax), and is added to the wax to make its density at room temperature just little higher than that of the water. When heated, the wax mixture becomes less dense than the water because wax expands more than water when both are heated. It also becomes fluid, and blobs of wax ascend to the top of the device where they cool (which increases their density relative to that of the water's) and then descend.
The underlying mechanism is a form of Rayleigh–Taylor instability which is named after one of the fathers of understanding surface tension Lord Raleigh and G.I. Taylor. It is an instability of an interface between two fluids of different densities (like the wax, water and tetracycline), which occurs when the lighter fluid is pushing the heavier fluid.This is the case with an interstellar cloud and shock system. In the case of the lavalamps there is an equivalent situation since when the gravity acts on the two fluids of different density. The falling stream of liquid then breaks up due to the Plateau-Raleigh instability which explains why and how a falling stream of fluid breaks up into smaller droplets. The driving force in this Raleigh-Taylor instability is that liquids, by virtue of their surface tensions, tend to minimize their surface area. The lavalamp has a metallic wire coil in the base of the bottle acts as a surface tension breaker to recombine the cooled blobs of wax after they descend. Psychedelic!

Friday, 4 November 2011

How is Surface Tension of Metals is used in Terminator 2?

See here for how surface tension of metal is used in T-2.

I love the Terminator series made by a fellow Canadian, James Cameron.  Still I think the best one is Terminator 2.  It had fantastic scenes with Terminator (played by the Governator/Arnold Schwarzenegger) and T-1000 (played by Robert Patrick.  The most awesome thing that James Cameron brought to the table in this movie was not the advancement in sci-fi with super robots, skynet or time travel teleportation (which are all cool) but rather the mimetic polyallow used in the T-1000.   

 The mimetic polyalloy of the Infiltrators T-1000 or the T-1001 is awesome as an endoskeleton enhancement.  It can do an other of things that the original T-800 Terminator cannot do.

Some advantages of the surface tension of liquid metal T-1000 are:
-It's center of mass can be shifted to bring greater power to blows in certain areas e.g. puff out its stomach if getting punched there
 -the surface tension can spall ahead of incoming blows to absorb and trap both weapons, projectiles, and physical strikes  (e.g. one move it has done is it takes a punch to and through the face, morphing to replace the impaled head with a pair of grasping hands, shifting the head out the side and shoulder.)
-it's surface tension can help it extrude at will any variety of slashing or stabbing weapons (e.g. like to kill John Connor's Foster parents)
-surface tension changing helps the T-1000 complete torso 180 degree rotation, the unit is more flexible, faster, and stronger
 -the change in surface tension also effectively impervious to mechanical damage, such as being dismembered, shot with bullets, or attacked with explosive devices with wounds closing almost immediately (e.g. when T-1000 meets his rival the T-800, the most brilliant scene in the movie, the shotgun blasts only stop the advancement of the T-1000)
-one other thing the T-1000 has in its arsenal are control nodes that can spread its influence to other machines and potentially other Terminators (reminds me of Maximum Overdrive by Steven King)

One disadvantages of the T-1000 is the surface tension is the
Low temperatures can cause the liquid metal to freeze, which inhibits its ability to move or shapeshift.
(so you won't be seeing him in the Finnish winter anytime soon).
High temperatures degrade its ability to maintain a disguise; after emerging from a burning truck, the T-1000 appeared in its default liquid-metal state and was only able to reestablish its policeman disguise after cooling for several seconds.
-Temperatures in excess of 1535 degrees Celsius like in the smelting plant at the end of the movie can incapacitate the T-1000

We have not caught up to Terminators T-1000 level although Boston Dynamics has some interesting robots nobody has been able to duplicate the incredible surface tension metallurgy properties of a T-1000 robot.

Since the mimetic polyalloy used in the Terminator movies is not real I felt that it could be discussed some surface tension properties of real metals.  Generally some of the properties of liquid metal are discussed.  Liquid metal consists of a slag which protects the metal at the surface and assists in temperature control of the metal.  The slag consists of a mixture of metal oxides and usually a by product of the smelting process. Underneath however the surface tension of the metal has some similarities to the surface tension of aqueous fluids. Surface tension which is affected by the temperature can change and gradients in surface tension can make a Marangoni effect in the metal. In the table below it shows that certain metals can be fluid at certain temperatures (900 C). 

Table: Surface tensions (mNm-1) of pure slag components at 1773K (900 C)

SiO2 (260) CaO (625)  BaO (560) SrO (600) MgO (635)  Al2O3 (655)  MgO (635) FeO (645) NiO (645)  MnO (645)  CrO (360)  Na2O (295)  K2O (160)   TiO2  (360)    ZrO2 (400)  Cr2O3 (800)  Fe2O3 (300)  CaF2  (290)  B2O3 (110)


From Mills
THE ESTIMATION OF SLAG PROPERTIES a short course in pyrometallurgy.
H. M. Lu and Q. Jiang*

Thursday, 3 November 2011

Learn surface tension. Escape the Matrix

 Imagine you wake up without having any idea where you are.  You get out of a bed that is new to you.  You look around a room at pictures that contain your face that you observe in the mirror next to the bed.  However, you have no recollection of the time or the place where these pictures were taken.  Your mind is clear though albeit a little cloudy.  However, your thoughts and actions are fast.  When you pick up the ball at your feet you feel that objects around you feel tangible and real even if your memory is blank of ever acquiring them.

Your heart starts to race and you panic a little.  Hyperventilating in short sportatic breaths your chest heaves in and out.  You world is enveloped in this madness like you just escaped a car crash..  You have two choices: you can accept this new world or you can understand it.  The latter choice of understanding it could allow you to escape it.  You want to get out of it and go back to a place that does not feel like a dream.

You turn on the tap to get some water on your face.  The water flows and splashes onto the white porceline.  You observing the water dripping from the tap as you shut the tap off.  You open the tap again and observe the water splashing to the bottom of the sink.  Although other people observe this everytime they wash their face in the morning you have a better eye for understanding surface tension.  You have studied the effect of surface tension in many different forms from when you were a child to studying the effects at University physics classes.  You learned the properties of water flowing over objects.  You understand how water can splash, converge onto itself and diverge into droplets.

Something is wrong!  Something is very wrong with the splish and splash in the sink.  You begin experimenting first by plugging up the sink.  Taking the soap next to the sink you add it to the water.  You splash it around making a little foam.  The soap is supposed to lower the surface tension but the surface tension remains the same.  You splash the soapy water but it behaves the same as if there is no soap.
Cupping water in your hands you throw it over the floor.  Again no change in how the sheet of water breaks up by adding a different amount of soap.  There is a hole in the matrix.  You are skeptical and your knowledge of surface tension takes you to another place in this potentially fictious world.

You walk down the black hallway.  Again this is all new to you.  You find the kitchen with a large open granite counters.  On top is a solid Jamie Oliver knife set.  You take one and in a fluid motion with all your
conviction that this world is not real you put the knife deep into your forearem and extend down to the wrists.  You start bleeding from your left arm.  You do the same to your right arm.  The blood hits the floor but does not splatter like blood is supposed to splatter.  It drips in a solid stream from your mutilated wrists to the floor.  It hits the floor like a waterfall rather than real blood. Slowly your body loses enough blood that you sit on the floor.  The checkered kitchen floor is now covered with a blood.  You close your eyes and you are reset.

In a computer room somewhere in an underground bunker on the other side of the world bespectacled men with bad haircuts look over a number of LCD screens watching your performance.  They modelled the surface tension using Langraian mean curvature flow mechanics in a eulearian space.  These computer governmental technicians did not calculate the correct surface tension or viscoscity from the blood or the soapy water to translate them into the subjects brain correctly.  The technicians did not develop the physics correctly which has led to a lot of mishaps in the matrix.  The information from the raleigh plateau instability and  non-oscillatory approximation when observing the drops of blood coming from the subject's wrist that were supposed to break up on the counter were not calculated correctly.  As the subject saw they flowed like a waterfall.  The CGI graphics that they were using came up short.  The graphics were only in its infancy and need to be recalculated so more subjects will not see the flaws to escape the Matrix.  The technicians were outsmarted by someone that understood surface tension.

Today computer scientists (better than the ones in the story above) have developed better CGI to show surface tension for movies.  Bad displays of physics appear in old  (and current Bollywood ) movies.  See how they are doing it using CGI,.