Wednesday, March 20, 2013

Lubricating liquids

The advancement of theory and experiment seldom proceeds at the same rate. Sometimes experiments results exceed the ability of theory to explain them, and at other times, theory provides results that can't be duplicated in the lab. A good example of this is a new paper in Physical Review Letters ($, but there is an open access summary). Using computer simulations, the researchers looked at what would happen if superhydrophobic spheres could be located at the interface between two liquids. Here's a visual:
As might be expected, the fluids not only didn't mixed, but flowed past each other quite nicely too. For those with fluid mechanics experience, the surface not only violated the "no-slip boundary condition", but also showed some of the highest slip lengths ever observed (or is calculated a better term?). This setup reminds me of dry water, where water droplets are encapulated by silica spheres. The over composition is 95% water, but it still flows like a dry powder.

As I said above, this is all good in theory, but putting this into practice is going to be rather difficult.
"[Author] Pierre-Louis is hopeful that experimentalists will soon check these predictions. A big challenge, already a problem for the patterned solid surfaces, is that pressure against the interface can vary widely, depending on the local flow speed of the fluid. 'Pressure is the biggest enemy for slip,' he says. It increases the penetration of the beads into the liquids, spoiling the reduced friction, and can eventually cause the air gap to collapse entirely."
So how could this be experimentally replicated? Gases can have greatly reduced pressures, but generally lack the cohesive strength of liquids. This is especially true for ideal gases, so non-ideal gases might be an option. Strongly non-ideal. So non-ideal that they are almost liquids. Which then brings me to this line of thought, which is admittedly half crazy: use supercritical fluids instead of liquids. The density of the fluids could be allowed to vary greatly, thereby reducing the pressure on the beads. The only downfall of course, is that any supercritical fluid that I know of is already at superatmospheric pressures, which defeats the whole purpose of this. (I told you it was a half-crazy idea).

Those are my thoughts at this point in time. Anyone else want to chime in?

Monday, March 18, 2013

Rheology, Beer and Motor Oil

For today's blog entry, please go to the Rheology Bulletin (OPEN ACCESS) and scroll down to page 10.

Now if I can just get this article cited 3 times, my h-index will increase by 1!

Friday, March 15, 2013

The Challenges of Deep Mining

Nature has a special section on gold this week. There are articles covering differing aspects of gold - it's chemistry mostly, but also a few about its mining. As regular readers of this blog know, I'm now working in support of the mining industry, so I found this following passage to be a very good description of some of the challenges miners face. While gold is mention in the article, the difficulties in mining are the same regardless of the mineral being sought.
"There are many factors that influence where and how deep a mining company will dig for gold, but in general “as you go deeper it gets more expensive and time-consuming”, says Steve McKinnon, a mining engineer at Queen's University in Kingston, Ontario, Canada, who specializes in designing deep mines. It also gets more dangerous.

Mining at depths such as those of TauTona (2.4 miles/3.9 km) presents many unique challenges in protecting the miners, says McKinnon. First of all, it's hot. The temperature at TauTona's deepest levels is a stifling 58 °C. Air conditioning brings the temperature down to a toasty but more tolerable 28 °C.
The rule of thumb is that the sun influences the first 500 feet or so of temperature and after that, the temperature increases 1 oF for every 100 ft in depth.
Then there is the risk that digging can fracture the rock around the pit, triggering a seismic event. “Sometimes that fracture process can be very violent, because the rock behaves in a brittle manner,” says McKinnon. “There have been events larger than magnitude 5” — equivalent to a moderate earthquake.

To minimize the risk, mines use 'yielding supports' that are able to deform as the tunnel walls move yet still retain their ability to support the structure. There are also networks of seismic sensors that constantly monitor the rock and develop a seismic 'fingerprint' for the region — any departure from an established baseline requires that workers be pulled out until seismic readings return to normal.
In other words, the ground support is far more sophisticated than Steven Speilberg would have you believe - wood beams. Granted, wood beams used to be used, but there are much better materials nowadays.
Engineers specializing in rock mechanics, such as McKinnon, also try to design mines in such a way as to minimize and control the forces exerted on the rock. Taking into account data on local stresses on the rock, and other factors such as the presence of nearby faults, they calculate the most favourable layout and method of ore extraction to minimize fracturing. This information helps engineers determine which bits of rock can be safely removed and which need to be left behind to support the rest — in much the same way as an architect decides where to put the pillars in a cathedral to hold up the enormous roof. This design modelling is “really at the limit of our technical ability now”, says McKinnon."
In other words, there is a large amount of engineering involved. Without it, you are relying on luck. You can find luck in a casino, but there is precious little of it thousands of feet underground.

Thursday, March 14, 2013

University Customs vs. Business Customs

This is just a couple of tidbits about how the the rules and expectation in a university setting are the opposite of the the business world. Keeping in mind that the students are the customers and the professors are employees:
  • At a business, employees need to park further out in the lot or even in back so that customers can park near the entrance, while at a university, the professors have reserved spots nearest the buildings and the customers need to park farther away.
  • At a business, the customers never complain about receiving too much product, while at a university, students always complain about lectures going too long.

Wednesday, March 13, 2013

The Greatest Thing FOR Sliced Bread

We've all heard the expression "The greatest thing since sliced bread" [*] - now here's your chance to improve on it.

NineSights (formerly NineSigma) has a Request for Proposal for improvements to the packaging of sliced bread. The unnamed client (more on that in a minute) has a short list of desired improvements, such as
  • Improve on-shelf merchandizing [sic] in appearance or ease of shopping for the consumer
  • Improve the consumer experience through an “easy to use” package format
  • Enhance the consumer perception of “freshness” for sliced bread
  • Enable flexibility in product production that accommodates varying sizes of sliced bread products from individual slices to full loaves of fresh bread
  • Provides an intuitive opening feature and re-closure feature for consumers
  • Provides a tamper evident package feature
  • Reduced cost from enhanced process efficiency or more economical materials/solutions
  • Package produced from sustainable materials
Is that all? Any one of these items alone is a major product development effort, but start trying to combine them and you really get headaches. Look at the last two items: Reducing costs AND using sustainable materials? If that were possible, everyone would be doing that already.

Innovative packaging is extremely difficult to achieve. Everyone one of us has experience firsthand with packaging materials and so we all think we are experts. We complain about it, we think it is wasteful and we could all do it better ourselves. That is, until we are directly asked. The demands on a simple package, even one as simple as a bread bag, could easily fill a page a paper in a 10-point font. For instance, it has to be approved for food contact, it has to be waterproof/resistant, it has to be clear, it has to be made of something that can be processed at high speeds on automated machines... And now to add these additional demands, without removing any of the previous requirements just makes it worse. I am truly elated that I've had very few experiences working with packaging.

On the upside, the customer can probably pay you pretty well. While they are not explicitly named, this description
"NineSigma’s client manufactures more than 200 million packages of sliced bread per year. Current sliced bread packaging consists of a printed polyethylene bag with a plastic lock closure. Additionally, some breads use an inner wrap consisting of a polymer film with an outer printed polyethylene bag with a plastic closure."
is pretty telling. The only national bread company that I know of that used an inner and outer bag is Pepperidge Farm, a seller of premium products (undoubtedly with a premium margin).

Good luck if you want to take this on, even as a moonlighting project. You will need it.

[*] The Wikipedia article on sliced bread is pretty interesting, including the section on a 1943 effort to ban sliced bread because of World War II.

Monday, March 11, 2013

What's Wrong With This Picture?

This was in the front of the company van - the one that takes us around the various buildings on campus:
Smoke free vehicle - check. Wear your seatbelt - check. No chemicals - wait, what?

So I guess the mixed gases in the air, the various food items, the people, their clothing, their notebooks, paper, computers, pens, eyeglasses etc. are all chemical free? Chemopohobia strikes again.

Friday, March 08, 2013

The New Lab...

How's the new lab coming you ask?
Does anyone know where the boxcutter is? It's around here somewhere.

Thursday, March 07, 2013

Anonymity (and Confidence)

Anonymity on the internet seems to be the hot topic of the week, so here is my take.

I started blogging quite some time ago. As with most blogs, the initial effort was pretty pathetic, something that nobody would claim as their own. That's fine. I'be been through that scenario many times in my life, whether it was starting grad school, taking out a USCF [*] license, or getting physically intimate with someone for the first time. You name it, we all have (or will be) in situations that are way outside our comfort zone. For too many people sadly, putting a toe in is as far as they get. They let their embarrassment get in front of them and they sell themselves short. If for whatever reason someone is reading this and thinks that they could blog too if only they could be a) good enough b) sure that they had enough material to last for more than a week c) whatever else... then please, take it from me, go for it. Dive in and never look back. Whatever concerns you have will take care of themselves if you are truly committed to the cause.

Rich Apodaca (@Rapodaca on Twitter) gave a number of reasons this week as to why someone - and chemists in particular - would choose to be anonymous on the internet. While I agree with all of his reasons, I think he missed a big one: lack of confidence. It takes a world of confidence to go out on the internet and post your opinions/comments/thoughts with YOUR NAME ATTACHED TO IT knowing that everyone can see it and criticize. This was extremely scary for me. While I have always known that I had a great education in rheology, it took me the better part of 2 decades to be able to CONFIDENTLY post my opinions about rheology to others, let alone criticize what other rheologists have published in renown journals. It was a very scary step for me and I am sure that that would be an equally scary step for others. For me, it was rheology, but for others it could be whatever particularly (sub)section of chemistry that you are (kinda) specializing in.

At the same time, I've never had any hesitation at all about "putting my name on it" (as Herm Edwards says). I can easily understand that in certain situations, anonymity is critical as what you say could have repercussions through your employer. Fine. I have no problem at all with that. If what you speak is true, it will show through your comments. On the other had, anonymous comments that are written so as to drive a certain agenda or to just incite an argument show through as clearly as a hydroxy groups shows through in an IR spectrum.

The fact that I have always put my name on my blog is actually rather striking to me in hindsight. I started this blog while at my previous employer, Aspen Research, when they were owned by the Andersen Corporation (i.e, Andersen Windows), so we were under the thumb of their IT department. Literally. I could go on for days about how heavy-handed they were, but what is always the most telling example to me and our clients was that we were not allowed to do a Google Image search. Why? Because the little thumbprints that showed up in the search results were potentially pornographic. Seriously. They were worried about little 1/2" by 1/2" pornographic images. We could never go to the websites hosting the full-sized photos since they were filtered out, but just the fact that we would have been able to view the little pictures was enough that we were creating a "hostile work environment" and so no Google Image searches were allowed. Again, this is only the tip of the iceberg as to how heavy-handed they were regarding internet access.

So when they suddenly said one day out-of-the-blue that they not only allowed but even ENCOURAGED to use social media (so long as we were civil, respectful and represented Andersen in a positive light), I was positively, absolutely, without-a-doubt, head-over-heels, taken aback with joy. Who wouldn't be? With that kind of permission, I began to write seriously. No, my early writing sucks. Whatever. Look at any other blogger's earliest writing. Practice makes perfect (although I am still have a long ways to go). But in all cases, I have always put my name on it. I can't imagine doing otherwise. I've published papers, given presentations, filed patents, etc. all with my name on it. What reason is there that some one wouldn't put there name on it? Rich has already given a long list; I've added a lack of confidence but argued that away; so what else is there? Start blogging and put your name on it.

[*] USCF = United States Cycling Federation. I thought that I used to ride my bike pretty seriously, but it wasn't until that thin little green postcard arrived in the mail in late March of 1986 that I decided either I was going to go all in or forget it. I'm sure there are people reading this that think they are good/great cyclists, having done centuries and whatever other rides are available. But would you ever sign up for a race where you were going to be viewed and judged in front of a public audience as to how well you rode? Think about that and tell me you're not scared. Somehow I found the guts to race and I'm glad I did. I never looked back and I never regretted it no matter how many races I got smoked at. That was a big wake-up call, one that I will never forget and I one that I use to teach others with. Blogging is no different. You sign up innocuously with Google for a blogger account, BOOM you get and suddenly it's like "Oh S*#t"! This is for real", and you either decide you are going to do it or you walk away.

Wednesday, March 06, 2013

Dow Chemical and Paris Hilton

Much like Paris Hilton or the Kardashian sisters [*] are famous for just being famous, I sometimes wonder if Dow Chemical isn't in the business of just being in business. They certainly aren't making news for innovative chemicals but rather for legal decisions.

I already mentioned the price fixing decision that went against them a couple of weeks ago. On the up side, there is a $2.5 billion dollar decision that the International Court of Arbitration confirmed in their favor from the failed K-Dow joint venture. I just wouldn't hold my breath on collecting that money soon. But there is also a couple of recent tax decisions that went against them. In one case, they were found to have illegally claimed certain materials and work efforts as R & D (meaning that it could be used as a deduction in their tax filings). It's only $8 million that we're talking about here, but the other case is much more significant. In that case, Dow tried to establish tax shelters and create $1 billion worth of tax deductions. When the judge issues statements such as "Dow viewed its tax department as a profit center" and "tax law deals in economic realities, not legal abstractions", you know you're in trouble.

It would be nice to see Dow Chemical proudly announce the development of a new polymer, one that they are going to really provide enough support for the long term development of the market (unlike the pull-the-pug-quickly effort for Questra).

[*] I never thought I would mention Paris Hilton and the Kardashian sisters in a polymer blog. The world works in strange ways sometimes.

Monday, March 04, 2013

Two Oobleck Videos - 1 Good, 1 Bad

Eric F. Brown over at "The Rheol World" has a new post of the guys from "The Big Bang Theory" having fun with Oobleck (cornstarch and water) on a music speaker. Sheldon Cooper does an adequate job of describing the phenomenon - it's not a complete description, but he certainly is not incorrect in anything he says.

Compare this with this awful video, only 6 seconds long and (about that many words too) which makes a total mess of the matter:
Oobleck is not thixotropic; it certainly shows signs of rheopexy, dilatancy and other non-Newtonian behavior, but not thixotropy.

This is another example of something I've discussed before: while the word "thixotropic" sounds like "thick", that association is completely inaccurate when it comes to understanding the meaning of the word. A thixotropic material will reversibly reduce its viscosity at a constant shear rate. When the shearing stops, the viscosity increases. The imaginary word "thinnotropic" would be closer to its true meaning.

Friday, March 01, 2013

Giving the Skin Off My Back

For very personal reasons, this picture on the right instantly captured my interest like few others ever have. The personal reasons are that I once looked like this, or something close to it. Let me explain.

On more than one occasion in my career, I've worked on developing medical adhesives. The difficulty in developing them is that they end up on human skin, which is very, very different than other "standardized" surfaces such as the various metals or plastics available, something I've discussed in more detail in the past. Just one important difference is that the peel tests measure the force not only of removing the adhesive from the skin but also the force required to deform the skin. Initially you test the adhesives on those artificial surfaces, but ultimately you need to move to human skin. That means you need a volunteer, and I certainly wasn't going to expose someone to something that I wouldn't test on myself. So it was off with the shirt to expose my rippling six-pack abs, bulging python arms no...the pasty white skin on my back. The back was the preferred substrate for testing since it was large and relatively flat (the measure peel strength of an adhesive will vary with the peel angle, so a flat surface is important for maintaining a constant peel angle). Someone would stick the pieces of tape to my back in parallel lines on both sides of my spine, with the tapes running perpendicular to the spine. As you would expect during development, there were multiple iterations in the formulations. Some weren't sticky enough while others were more than a bit too aggressive, which means that I have literally given "the skin off my back" in order to please clients. (How many other chemists can say that?) [*]

The picture and the research were an embarrassing wake-up call to me as I never knew skin was mechanically anisotropic in the planar direction. Skin in under anisotropic tension are caused by the orientation of the underlying collagen fibers. This anisotropy could have a large impact on measured adhesion values if the principal directions varied inconsistently with the direction of the tape. So now you may see why that picture was so captivating. The researchers were not only measuring the tensile strength of the skin, but also at different orientations. The underlying dashed lines in the picture are Langer lines, which are believed to indicate lines of tension in the skin. Langer originally discovered them indirectly 150 years ago but cutting circular holes in the skin and noticing that they deformed into ellipses. The point of this latest research was to pull ASTM dogbones to directly measure the mechanical anisotropy and see if in fact the Langer lines are correct. Not surprisingly, the researchers found that in fact the tensile properties of the skin are consistent with the Langer lines. And fortunately the lines run perpendicular to the spine, meaning that all that back-testing data is just fine. Wheeew.

[*] Some of the adhesives also ended up on EKG electrodes, which meant that I would be wearing some of those buggers on my chest. My wife used to joke that if I ever had a heart attack, the EMT's would be shocked to cut open my shirt only to find that I was "pre-wired" and ready to go.