Thursday, 30 June 2011

Why my ink stinks?

I was printing using an old inkjet printer. I tried to get some quality images printed but the ink ran into each other and the quality stunk.  So I started looking into and understanding why?  I took the ink out of the compartment and held it up in my hand to look at this liquid.  It is a far distant ancestor to the first inks from the Chinese made from around 256 BC in the end of the Warring States Period and produced from soot and animal glue.  My ink in my printer is also far distant from the Indian made 4th century BC called masi, and made of burnt bones, tar, pitch, and other substances.  I doubt the ink producers at Hewlett Packard, Lexmark, Sun Chemicals or Xerox still use bones and animal glue in their ink composition.

So why does my ink stink out of my old in jet printer?  Some of the ink properties that are crucial for performance include low viscosity, optimum surface tension, nanometer particle size for a start.  So I will focus here (as the blog is entitled 72dynes) on the surface tension.  Ink requires that you have the right surface tension and luckily you can measure this surface tension quickly and easily using a tensiometer.  The surface tension affects the substrate wetting, print quality and and adhesion.  It needs to be optimized to improve the jet stability and performance.  An ink formulator (and yes they are still formulating better inks) after 2000 years needs to balance the demands of good jettability, substrate adhesion, print image quality and drop spread.

When parameters like the surface tension are not optimized my ink starts to stink.  When the ink surface tension is much lower than the substrate good substrate wetting and a good drop spread and therefore surface energy of the ink on the paper (or whatever you are printing onto) can be achieved.  If the ink surface tension is too low it can increase it can increase the drop spread reducing the resolution like in my case.  In these case we are talking about static surface tension.

For a dynamic process such as inkjet printing the ink surface tension at extremely short time intervals also should be measured.  The time it takes to go from the ink cartridge to the paper for example.  The dynamic surface tension is thus a critical parameter to understand the time dependent characterization within milliseconds.  So depending on the inks dynamic surface tension dictates how fast you can print the report out of your ink jet printer.

So to ink still stinks and I have gone through a stack of papers trying to print this document!!!   I am not mad since I learned something valuable about surface tension.  Static surface tension is an equilibrium surface tension measurement and represents the minimum value seen by the dynamic testing.  The dynamic testing can show that the surface tension my ink decreases with time due to surface active materials in the sample migrating to a freshly developed surface and reaching equilibrium.  In any case, the dynamic surface tension will not decrease below the static (equilibrium) surface tension over time.

Thursday, 23 June 2011

A better pan by accident

Recently, I moved into a new place.  We were buying some cookware and found an inexpensive pan.  It was smooth and water resistant.  It was made of Teflon.  Most new pans after the 1960's contain Teflon.  Teflon is such a wonderful material particularly because water on the surface of the pan has a contact angle approaching 110 degrees making it incredibly non-sticky.  Also when cooking you do not need to use as much oil because of the oil will also be repelled by the surface of the fluoropolymer.  I think the most amazing thing about teflon is that it was discovered by accident.  Something that we use everyday was discovered by accident. 

In 1941 a scientist by the name of Roy Plunkett worked for a company owned called Kinetic owned by DuPont de Nemoirs and General Electric.  He was researching a new CFC for fridges.  CFC is a fluoropolymer.  One interesting thing about fluoropolymers is that Fluoropolymers share the properties of fluorocarbons in that they are not as susceptible to the van der Waals force as hydrocarbons (like oils). This contributes to their non-stick and friction reducing properties. (I guess you can compare your non-stick teflon pan with a regular pan with oil and compare the contact angle).

The trade name Teflon is polytetrafluoroethylene (PTFE).  PTFE was accidentally invented by Roy Plunkett of Kinetic Chemicals in New Jersey in 1938.  Plunkett checked a gas pressure bottle containing a new CFC refrigerant.  Tetrafluoroethylene gas in its pressure bottle stopped flowing indicating a stuck valve.  Since Plunkett was measuring the amount of gas used by weighing the bottle, he became curious as to the source of the weight as most of the gas should have gone out of the bottle.  After making an explosion proof chamber Plunkett resorted to sawing the bottle apart.  The source of the weight was discovered with a coated waxy white material inside.  After further inspection they noticed it was slippery and water resistant.  It was polymerized perfluoroethylene.  The iron from the inside acted as a catalyst.  It was registered as a trademark under the name Teflon in 1945 and three years later DuPont was producing 900 tonnes of the material.  Later in 1954 a French engineer named Marc GrĂ©goire wife told her husband to coat a pan with this new resin making the first teflon pan later forming the company called Tefal.  A couple of happy accidents makes cooking simpler.  

Wednesday, 22 June 2011

Liquid Courage

So my previous post I talked about drinking alcohol a.k.a liquid courage (this could not be more true in Finland since people are quite shy but after a few out!!).  Even though alcohol has so many physiological, sociological and other effects and is quite a clear anesthetic there are still a lot of undetermined things about ethanol.  It is understood that it can easily interdigitate due to its size into the cell membrane and change the membrane's physical properties.  This could change the phase transition, the fluidity, the lipid movement, dipole potential and even affect the amount of polyunsaturated lipids (REF) at the synaptic membrane (this is over chronic ethanol ingestion).  All these effects would affect the proteins where these lipids are embedded giving people slower reaction times. 

One assay on how understand the effects of alcohol on the membrane is to use monolayer films with compression isotherms.  A single layer film is deposited on a subphase of a trough of a known area (usually water) and the area per molecule can be calculated (this was first performed by Benjamin Franklin).  Then two teflon barriers on opposite sides of the trough slowly compress changing the trough area.  The area per molecule can be calculated.  The surface tension and other parameters like surface potential can be recorded if available.  Usually the surface tension is recorded to give a graph of surface tension vs. area per molecule.   What happens when ethanol is added to this type of system?

A pretty comprehensive review of alcohols and anesthetics was made by Frangopol et al. from Bulgarian (click for full pdf) uses compression isotherms.  When adding a anesthetic like alcohol two things can happen either expansion or condensation of the film.  It is known that alcohols that form hydrogen bonds with water molecule are thought to disrupt normal membrane function by penetrating into membrane domains and hydrophobically interacting with the membranes.  Increasing the alcohol concentration thus will cause increase in membrane fluidity.  When the surface tension in the compression isotherm was measured it was confirmed that this could produce condensation in the membrane.  So ethanol can both penetrate the film and lower the substrate surface tension.   The alcohol also affects the phase transition temperature as well.  Based on the observations from the compression isotherms, calorimetry and some other experiments, the partitioning of alcohol into lipid membranes is governed by three major forces: (i) hydrophobic repulsion between alcohol and water (strongly favoring membrane partitioning); (ii) a much weaker attraction of the polar group of the alcohol to the head group of the lipids, and (iii) a weak repulsive effect due to the intercalation of the alcohol acyl group into the lipid bilayer.

It is a subject of much debate as to whether ethanol and anesthetics just affect the membrane and change the membrane proteins (embedded in the membrane) or whether ethanol and anesthetics disrupt the proteins directly.  The lipophilicity of ethanol and anesthetics as well as the very fast action of them makes me think more of the former being the more likely theory but it does not exclude the possibility for specific receptors.

PS1 One way to relieve some of these symptoms is to eat fatty foods (or just don't drink).  This is one reason why eating a big burger after a night of binge drinking might help you literally squeeze the ethanol out of the membranes so you can excrete it.

PS2 An interesting fact about redheads is that they need more anesthetic than others due to a defects in the melanocortin-1 receptor gene (MC1R) which also gives leads to the phenotype of redhair.  This gene MC1R gene may be involved with complex neuromodulatory regulation within the central nervous system and it is not quite clear as to whether a specific anesthetic attaches to it.

Saturday, 11 June 2011

Drinking last night....

I wish I was just puking rainbows

I was drinking last night for a Kesäjuhlat (summer party) for my sports club.  I had this elaborate plan that I would get to the airport really early.  That plan was spoiled when alas I past out, then woke up just in time to catch my 6:30 flight.   The all night sun helps wake one up so I am happy for that.  So now I am feeling a little bit drunk and a little bit sick.  I am actually surprised they let me through the security check.  If they asked it would go something like this.

Security: Are you okay?  Are you drunk?
Me: I am in Finland it is kinda hard not to be.
Security: Take off your belt please. 
Me: This good? (I take off my pants then I get arrested and denied boarding)

So as I am writing this I am waiting for my plane so I did not get arrested. However the second one could still be possible.  So as I am feeling sick.  I would love to understand the surface tension of the stuff I should be throwing up: bile (bile acids and salts). They are steroid acids and are compounded with a cation usually sodium.  In humans taurocholic acid and glycocholic acid are present.  Since they align at the oil water interface the bile reduces the surface tension to 5 dynes/cm (oil water interface) as compared to 40-50 dynes/cm at the air water interface.  They probably used an instrument like this Langmuir Blodgett trough to understand the compressibility of the puke errr I mean bile.  The bile together reduces the surface tension more than the compounds alone (REF).  O'Connor and all also have an nice article measuring the surface tension these at different pH's
ect.  With this knowledge I am pretty sure the surface tension is not the thing that is making me sick though....

Friday, 10 June 2011

Surface tension of Superfluids

When scientists looked into the stars specific stars called pulsars they found something very very interesting on the surface.  They found superfluids that on the surface of the star behaved very very funny that when rotating at the correct speed they create a vortex which is recently being studied by a supercomputers at the University of Washington. 

These superfluids can be observed on earth by supercooling helium.  Liquid helium-4 itself becomes a superfluid when cooled to within a few degrees of on the Kelvin scale (minus 273 Celsius or minus 460 Fahrenheit), and the resulting lack of allows it to seem to defy , flowing up and over the sides of a container.  It has no viscoscity but does have a surface tension so this weird combination will cause a superfluid when placed in a glass to roll up the side of the glass and go down the other side.

The surface tension of super cooled liquid helium has been calculated to be 0.3 dyne/cm and by levitating it magnetically and studying its vibrational modes the surface tension could be determined to be 0.375±0.004dyne/cm between supercooled helium at the hydrogen interface. (no wonder when stirred it loses its fluid properties-see article above)

Why are superfluids studied?  Who cares.  It probably gets the guys studying them to get some girls back to the lab.  Do you want to see my supercritical fluid? you want to see my errr...  Anyways there must be some point even if laymen do not really understand it.  Besides being really cool (and the girls).  Because of the strange properties particularly the refractive index of the superfluid it can be used for spectroscopy experiments in particular Superfluid Helium Droplet Spectroscopy (SHeDS).  It has also found super precise things like gyroscopes when needing to understand gravity (think about that next time you are in a plane).  Possibly some more studies will help get more appreciation of superfluids so they can really become...super!

Wednesday, 8 June 2011

Pimp my Ride with some Chrome Rims

I like cars.  And when you see a nice car (or some souped up Honda Accord like in the Fast and Furious Five aka the worst movie ever made)  you might appreciate the car more.  Those rims shine a block away and seeing rims on a nice car makes it all the better.  To lightly paraphrase Chris Rock:  'We love rims.  Put shiny rims on any car if you would let them.  Guys would put rims on a toaster if you would let him.  Look at those 22's they are spinning.... they are spinning....they spinning.....'

But what makes rims so much more awesome then the plastic hubcaps on your Ford?  The chrome job!  The chrome you can see the shine of it from a mile away.  It looks clean and polished.  Car enthusiasts and anybody that likes rolling rims can thank some predated chemists or alchemists for starting the initial endeavors that would take us to chrome plating.

We go back to the middle ages with quasi scientists called alchemists.  Alchemists goal was to use something called the Philosophers Stone to change lead into gold.  As you know this is impossible but later these alchemists turned into chemists leading the way into discovering new understanding of science during the industrial revolution (1760 to 1830).

As you know with any new discoveries and for the discoveries that will eventually get to chrome plated rims parallel events need to happen.  This is why some science should never be arrogantly ignored while other science gets funding.  If that were the case we would not get rims.  Two parallel discoveries happened in addition to advancements in chemistry.  The first was the discovery of chromium in 1779 by Vauquelin in crocoite (lead chromate ore) and the subsequent reduction of the chromium by reduction with charcoal at high temperature 19 years later.  The second multiple events that occurred were from three scientists that played around with electricity Micheal Faraday (laws of electrolysis), Alessandra Volta (electric pile) and Humphry Davy (theory of chemical affinity and early electrolysis) in the 1800's.  Their work got us closer to chrome plating but as you know many horse drawn carriages did not have rims so we had to wait another 100 years before you could get your 22's.

The earliest work for chrome plating was done by a Frenchman named Junot de Bussy in 1848 who made a patent for electrodisposition of chromium.  Seven years later Bunsen published a paper on chromium followed by Geuther two years later in gottingen, Germany showing the first detailed account of chromium plating.  The later uses trivalent chromium plating using chromic acid solution which may have contained residual sulfuric acid which keeps the trivalent chromium from oxidizing at the anodes.  This is important as the sulfate-based bath that uses lead anodes that are surrounded by boxes filled with sulfuric acid (known as shielded anodes), which keeps the trivalent chromium from oxidizing at the anodes. However, like a lot of science he might not have done a thorough investigation about why it worked.  It worked!!!  This lead other researchers to further develop trivalent chrome plating (hexavalent chrome plating however was soon to be discovered).

The first chromium metal was obtained by electrodeposition in France. This first result was realized by electrolysis of an aqueous trivalent chromium solution, published and patented in 1848 by Junot de Bussy.  In 1854, Bunsen studied the influence of the cathodic current density on chromium deposition using a hot chromium chloride solution, with separation (porous pot) of anodic and cathodic compartments. The importance of the separation between anodic and cathodic compartment was considered a major discovery for a long time and was further developed by others researchers, including Placet and Bonnet in 1901, Voisin in 1910 and Recoura in 1913.  Another researcher, LeBlanc, concluded that he could not electroplate any chromium from solutions of chrom alum or chromium sulphate and there was much controversy about depositing any chromium from any solution.  Sometimes failure leads to breakthroughs.  In 1905 two researchers named Carveth and Curry who worked at Cornell University concluded that the findings of Palcet and Bonnet were in fact correct and they also produced chromium plate from chromic acid solutions. These discoveries made trivalent chromium processes available leading to some pretty nice rims.  However, impurities in the metal, disposition of thicker coatings and in some cases color for decorative chroming led people to discover an alternivative method. 

Bancroft in 1906: “ The real solution from which to deposit chromium is not chrome alum nor sulphate, it os chromic acid”.  This lead to making the process of hexavalent chrome plating where you use a slightly different setup than the trivalent chromium plating.  This process included higher temperatures, higher current density and lastly the bath must be maintained below 30 dynes (I will come to this in a second).  So finally, finally, finally you got your nice rims (so you can put it on your 1993 Honda Accord with a racing stripe).

But your rims come at an additional cost.  A hidden cost.  The workers that work with this stuff can suffer extreme health effects if the hexavelent chromium is not maintained in the bath.  To maintain it workers use fume suppressants that must be strictly regulated using a stagalometer or even better a tensiometer. Some chrome platers are using this tensiometer in Asia and the US to maintain the bath surface tension so hexavalent chrome does not go into the air destroying lungs tissue.   

So buy those rims.  Make them spin.  Pick up some ladies with them.  But just be reminded that over two hundred years of research and some workers safety went into making them.  

Tuesday, 7 June 2011

Washing Vegetables Properly

I am in Central Europe and I am afraid to eat vegetables.  On the plate of chicken stuffed with goat cheese and roasted potatoes sits a cucumber, some lettuce and a tomato.  Normally my mother would tell me to 'eat my vegetables' however a quick facebook message said, 'don't even touch them.'  Why? 

Over 2,300 people sick and 23 deaths have been linked to eating raw vegetables.  An unusual lethal superbug strain of  E.Coli O104 strain was uncovered.  I am not an E.Coli expert but apparrtently O104 strains are almost never (normally) resistant to antibiotics.  This outbreak is said to originate from vegetables in Almeria, Spain has caused such widespread panic around Europe resulting in 200 millions of euros per week of lost revenue for Spanish and other European producers.  It has also caused me some indigestion from the lack of needed fiber.

E.Coli is not the only nasty stuff on the surface coming off the cucumber.  Plants are grown in vast fields surrounded by a lot of bugs and other pests.  Crop control means that herbicides, fungacides and pesticides are used to control for these pests.  These chemicals control weeds, fungus and pests from eating some expensive cash crops before you do.  Monsato, Dow and other companies make these chemicals to spray in the fields.  These chemicals have sprayed with proper concentrations determined by the surface tension of the chemicals so the drop size is the correct size for proper coating of the vegetetables.  Like these new deadly strains of E.Coli you would not want to eat these chemicals.  So how do you get them off?  You need to wash them!!! 

Companies that produce the vegetables need to wash the vegetables thoroughly.  This may be something that is amiss with the vegetables affected by E.Coli.  Good quality control is not in place.  However, some companies to control for the pesticides, herbicides and fungacides have started using a surface tension device.  They wash their fruit and vegetables then test the effluent water for these pesticides, herbicides and fungicides.  Once they are below a particular surface tension then they are free to go to the stores where you can buy them.  Maybe soon I can munch on some vegetables.  Hopefully, without having to ingest E.coli, pesticides, fungicides and herbicides with my meal.  Learn here how to wash your vegetables properly.