Thursday, June 30, 2011

BPA Wrap Up

Allow me one more post on BPA (bisphenol A) before we move on to something much more fun tomorrow.

Exposing humans, animals and the environment to chemicals is a serious consideration, but the emphasis is on "serious". Emotional approaches such as demanding that "absolute or total safety" be shown and portraying chemicals companies, their executives and customers as evil incarnate are not "serious" arguments. Ever.

Here are my questions on BPA that need to be addressed:
  1. At what exposure level will BPA have a real, measureable effect on people? Keep in mind that exposure level can and will change with exposure route (oral vs. contact vs. inhalation) and so a blanket statement cannot be provided.
  2. What alternative chemical(s) will replace BPA? Are they truely safer or have they just not been studied as much? Will we just be endlessly chasing our tails looking for a "totally safe" alternative when none exists and BPA is the best choice?
  3. As I've said numerous times, a system is optimized by optimizing the entire system, not by optimizing the individual components. Given this, our concerns cannot be on BPA alone, but the entire system that it is part of. How is this being addressed?
So that will be enough on this topic for a while, unless something really big shows up, which I doubt. Answering questions like these is not something that happens quickly, no matter how much we desire it.

Wednesday, June 29, 2011

BPA Followup (2/2)

This is a continuation of yesterday’s post regarding absorption of bisphenol A (BPA) through the skin. As was mentioned, an anonymous reader brought to my attention two research articles regarding the subject. One article was discussed yesterday; I’ll now discuss the other research article (open access).

I thought the results found here were quite interesting (I wasn’t expecting to read what they found), but unfortunately the researchers came across as having an expected outcome rather than looking at the results objectively as you will soon see.

The research effort in this article looked at the fate of BPA in human and pig skin. I’ve heard numerous times over the years that pig skin is probably the closest animal skin to humans, so I can see that the authors are trying to (re)establish pigskin as an acceptable model for human skin in future studies, although I’m just going to focus on the human skin results here today. I’m also not going to explain all the details of the setup, but basically they took skin samples (from the abdominal region [*]) and placed them against a collection media. The BPA would be applied to the surface, diffuse through the skin and into the media. The BPA was labeled with 14C atoms so that they could be found later in the surface of the skin, the skin itself and the media.

About 45% of the original 14C was in the media after 3 days, while about 41% was in the skin itself. A very large percentage of the material in the media (39% points) was metabolized either as BPA-glucuronide or BPA-sulfate, while only 12% points of the BPA in the skin was changed.

While numbers do seem to indicate strongly that BPA is absorbed through the skin, the authors make a statement limiting the impact of the research by those wishing to raise the alarm about potential dangers:
”The conjugation of BPA, at least with glucuronic acid, results in the cancellation of the estrogenic activity of the parent compound…it could be concluded that the high biotransformation rate of BPA by the skin does correspond to metabolic detoxification. .”
"Cancellation of the estrogenic activity" and "metabolic detoxification". Why didn't this make it to the headlines? The fact that absorbed BPA is no longer BPA is a game changer. Future research in this area should now focus on what the effects of exposure to BPA-glucuronide and BPA-sulfate are.

I don't understand why these results were downplayed, especially since these sentences are the second and third from the end of the article (overlooking the very short conclusions section). Remember how I said that the authors have an objective in mind? They show it with last sentence of the article:
”This remains highly speculative as BPA conjugates may be converted back in the parent compound at the level of target tissues.”
Somehow it was beyond them (and their reviewers) that this report should change the direction of future research, but they just didn't want to go there. Very sad.

[*] An earlier post showed that abdominal skin was more porous than skin in the palms - looking at the graph in that post, I’d call it about 50% more porous. I don’t see that being much of an issue here since the results were mostly qualitative.

Tuesday, June 28, 2011

BPA Followup (1/2)

An anonymous reader tipped me off to a couple of articles related to BPA absorption through the skin. Fortunately both articles are open access, so you can read along with me. I'll cover one article in this post and the other article in another post.

C & E News (Stephen K. Ritter, Transdermal BPA Exposure Confirmed, Chemical & Engineering News, ISSN 0009-2347) issued the following statement about the articles:
"Daniel Zalko of the French National Institute for Agricultural Research, in Paris, led a team that measured the diffusion of 14C-labeled BPA through samples of pig skin and human skin. A significant amount of BPA diffused through both types of tissue and was metabolized to glucuronide and sulfate derivatives (Chemosphere, DOI: 10.1016/j.chemosphere.2010.09.058). Separately, Harvard University’s Joe M. Braun and coworkers monitored the diets and analyzed BPA in urine samples of 389 pregnant women. Cashiers had the highest BPA concentrations in their urine; teachers and industrial workers had significantly lower concentrations (Environ. Health Perspect., DOI: 10.1289/ehp.1002366)."
Being a publication of the American Chemical Society, you would expect C & E News to provide good coverage of technical research, but as you will see that is not the case.

Looking at the second article first, it looks like Mr. Ritter only read as far as the abstract of the article, which states:"By occupation, cashiers had the highest BPA concentrations". That seems pretty clear cut, but looking into the article, the researchers themselves question the result:"These results should be interpreted cautiously because estimates from cashiers were based on 17 women and were attenuated with adjustment for socioeconomic factors." That's pretty clear cut to me.

I was pleasantly surprised to so that the authors don't stop there, but continue to criticize their own efforts in the following paragraphs:
"There are several limitations to this study. First, our results and others demonstrate that a single spot urine measurement has the potential to misclassify BPA exposure (Mahalingaiah et al. 2008). Second, many of our predictor variables were measured imperfectly, and we were missing some potentially important sources of exposure. We did not have women’s occupations classified by an industrial hygienist, which likely resulted in misclassification of this variable. Furthermore, the dietary variables used in this study were not originally designed to assess BPA exposure, but rather pesticide and mercury exposure. In addition, urinary BPA concentrations likely reflect exposure over the last day, whereas dietary questionnaire data reflected consumption over a longer time (weeks). Third, we did not collect information regarding other potential sources of BPA exposure including plastic or paper/cardboard use, packaged food consumption, medical devices, medications, dental treatment, or amount and type (tap, bottled, or well) of water consumed during pregnancy (Carwile et al. 2009; Gehring et al. 2004).

An additional limitation is the imperfect correction for urine dilution using urinary creatinine concentrations. Pregnancy-induced changes in creatinine metabolism and excretion may occur independently of BPA metabolism and excretion, so the degree of correction of urine dilution may change throughout pregnancy. Our results suggest that creatinine concentrations become progressively lower and more variable throughout pregnancy. Other measures of urine dilution, such as specific gravity, have been used and should be compared with creatinine patterns in pregnancy in future studies (Mahalingaiah et al. 2008)."
(Note: Urine concentration can fluctuate greatly with water consumption, so the researchers attempted to compensate for it by considering the ratio of BPA to creatinine in the urine.)

I have several comments on this situation, both good and bad. Given all of thoughts of the authors, I think we can safely treat the "cashiers have higher BPA levels" as unproven. Further research might show it to be true, but this research doesn't.

But what's with that strong statement in the abstract? I'm assuming the authors put it there, but then how did the reviewers let that pass? Or did some editor add it? And how come C & E News only read the report that far?

At the same time, I highly praise the researchers for discussing the shortcomings of their research, a very rare example of quality scientific reporting. Sadly, when that level of integrity was shown in this research, C & E News didn't even catch it. That would make better copy than what was actually written.

Monday, June 27, 2011

Gas Chromotography & The Supreme Court

It isn't often that a Supreme Court justice mentions a gas chromatograph in their opinions, but it did happen this last week in a case involving a drunk driver. We don't do forensic testing here at Aspen Research but being an analytical lab, I certainly am well aware of the potential shortcomings of any analytical technique. Such shortcomings need to be addressed in a court, not ignored as being unimportant (you'd want it that way if you were on trial, wouldn't you?), and that is the issue at the heart of this decision.

This case follows closely on the heels of a similar case that I wrote about a few years ago (the Melendez-Dias v. Massachusetts case). In that case, the Court found that a report from an analytical lab could not just be submitted as incontrovertible evidence, but that the defendant had the right to question the person who prepared it.

In the newest case, the Supreme Court clarified that last sentence to mean that you have the right to question the person who prepared it. Literally. Not their supervisor or another colleague, but the actual person who did the work.

I am all in favor of this, and can't see why anyone with scientific training would be against it. In any measurement, there are always a number of things that can go wrong, and the court knew this. A specific example was given in footnote 1:
"In order to perform quantitative analyses satisfactorily and . . . support the results under rigorous examination in court, the analyst must be aware of, and adhere to, good analytical practices and understand what is being done and why...Even after the machine has produced its printed result, a review of the chromatogram may indicate that the test was not valid. Nor is the risk of human error so remote as to be negligible. Amici inform us...a single forensic laboratory produced at least 206 flawed blood-alcohol readings over a three-year span, prompting the dismissal of several criminal prosecutions...An analyst had used improper amounts of the internal standard, causing the chromatograph machine systematically to inflate BAC measurements."
(I removed all the references so as to make the quote more readable. Isn't it cute that she calls the GC a "machine"?)

What really bothers me though, are the arguments against having the analysts defend their work. Again from footnote 1 (yes, it was one big footnote):
"...the State presented testimony that obtaining an accurate BAC measurement merely entails “look[ing] at the [gas chromatograph]machine and record[ing] the results,”..."
Merely?! Merely?! Merely?! Unbelievable. Any junior-level chemist-in-training can punch a dozen holes in that argument, and yet 4 justices agreed with that argument.

Friday, June 24, 2011

Art - from Ocean Beach Junk

The Artula Institute has established the Washed Ashore art program, taking pieces of plastic found on ocean beaches and combining them into sculptures. You will have to click over to the site to see most of the artwork as most pictures of it are incorporated into a Flash slideshow and I certainly don't know how to download any pictures from that. The fish you see above is about 15 feet (5 meters) long. And keep in mind that this garbage came from the shoreline, not any of the various Garbage Gyres.

While I do think it is interesting art to look at, I am of course greatly bothered that this much junk exists on the beaches in the first place. Garbage has no place being in the ocean.

Thursday, June 23, 2011

Older Workers

Paul Sturgeon has an excellent post today about hiring older workers. I strongly recommend you read it as he puts things much better than I ever could. Let me just throw you a small excerpt as an example:
"The company-employee loyalty is gone, for the most part, overcome by the realities of a global economy, mergers and acquisitions, a demand for short-term business results, and a host of other factors. What you have now is a situation where the average Gen X and Gen Y employee is changing jobs every 3-4 years. The bottom line is if you want someone today who is very likely to be with your company for 10 years, do not overlook someone who is 55 or 60 years old."
As I said, read the original article.

Wednesday, June 22, 2011

More on Drop-In Replacements

In yesterday's post on my dislike for "drop-in replacements", I pretty much criticized the whole effort and didn't have much positive to say. Today's post will expand on my thoughts but also suggest a positive path forward.

As I stated then, my rejction of drop-ins is based on experiences (detailed below) showing that not only is it pretty much impossible to match all of the technical requirements, but also the economics are just not there either.

One of my first major assignments in my career was to develop a hot-melt-based adhesive as an alternative to the existing solvent-based adhesive. Things were going along fine from the technical end, but trying to get the marketing department to consider switching existing products to the new adhesive was impossible, and getting the accountants to calculate an NPV for the capital investments needed was equally daunting. Certainly there were advantages to the new adhesive and technology. Even 20 years ago, environmental concerns existed, so the fact that the new adhesive was "solvent free!" and "green!" was not lost on anyone.

Additionally, since there was no oven and thermal oxidizer needed in production, the changeover products would be a lower cost, but that argument I soon found was as effective as trying to convince someone to buy a new car just because it will get better mileage. You need to do an awful lot of driving with really expensive gas to make those numbers pay off. [*] The marketers were not willing to risk replacing a perfectly performing product with a new product that probably won't work in the exact same way, all just to save a few pennies per roll.

Where I really started to get buy-in is when I started developing new products. Then the coin was reversed - the new adhesive had presumption and the solvent-based adhesives were challenged in attempting to displace the hot-melt adhesive. This was a life lesson that I've never forgotten - don't develop drop-in replacements, do develop new products.

So that would be the advice I would pass on to the people developing new bio-based routes to existing monomers. Don't do it, or at least, don't call it a "drop-in", because it won't be and no one will take the chance on it. Do develop the monomers if you wish, but look for ways that they are better or different than existing monomers. Again, those impurities will be the key, as the main component will not be different. And look at developing new monomers, especially ones that would be far too expensive to make in beakers, but can be made by microbes with the ease that biochemistry mocks us.

[*] Say you upgrade from a 15 miles per gallon (mpg) gas hog to a new Prius for $20,000 (after trade-in) and start getting 50 mpg. If you drive the typical 12,000 miles a year, you will now only need 240 gallons of gas per year instead of the 800 gallons you used to need, a reduction of 560 gallons. At $4/gallon, you will save $2240 a year, so that the savings pay for the new car in 8.9 years. And that's just to break even.

Tuesday, June 21, 2011

Drop-In Plastics?

When an email starts out like this: my immediate response is "NO!" (although I certainly would love to answer "YES!"). I group this type of email as equivalent to the Nigerian prince letters.

A drop-in replacement? It doesn't take too many years for a chemist or an engineer to discover that there is no such thing as a drop in replacement, especially for a polymer. Despite all the marvelous technical equipment that will allow us to analyze a sample in ways that still can boggle the mind after 21 years in the industry, most of these techniques fall far short of what is needed. (Specifically, I would love to see a tremendous increase in transient rheology, but that is another story for another day.) So regardless of how much a material may seem the same based on the technical data sheet, it won't be, and more importantly, it won't be in the same in some way that is really important to your process - you'll need more heat in one zone, you need to increase cycle time, you need more downtime for maintenance... something will come up, guaranteed. And if it doesn't, then you are a poor unlucky person, as all that luck that you used to make your drop-in replacement occur should have been used to win the lottery.

For whatever reason, I did scroll down further and saw that there might be some hope yet. The talk is from Draths Corporation and their bio-based technologies for making monomers. Here's a lower excerpt from the screenshot:This isn't quite as bad as I imagined at first, as creating a drop-in monomer replacement is somewhat easier, although it's always the impurities that kill your product in the reactor. The impurities from a bio-based monomer will be completely different than those from a petroleum/chemical-based one, and that difference could alter any and all of the rates in the polymerization (initiation, propagation, chain transfer...). Removal of impurities can be done, but that adds a real expense to the chemical.

I'm also curious about the three straightforward steps needed to convert the muconic acid into terephthalic acid and how "green" those steps are. This is one enantiomer of muconic acid:
with an empirical formula of C6H6O4.

Terephthalic acid has an empirical formula of
C8H6O4, so an extra two carbons need to appear from somewhere. Is that chemistry green?

All in all, a "drop-in plastic"? Certainly not.

Monday, June 20, 2011


Viscosity is something that everyone is familiar with, but only in the most qualitative of senses. Consider these examples:
  • While people can tell which liquid is more viscous than another one, no one is able to quantify it just by looking at a liquid. For instance, water has a viscosity of 1 cPs (0.001 Pa s). So name a fluid that has a viscosity twice that of water. Or looking at it differently, how much more viscous is honey than water? 2 times? 10 times? 100 times? Or even 1000 times? (Answers below).

  • When the viscosity of a fluid is measured, typically only one or two significant figures are used. For instance, in some recent work for a client, they had a thick water solution with a viscosity of 350,000 cPs. There is no way that I or anyone else could measure this to 351,000 cPs or 349,000 cPs or...

  • Given this, it's almost as if viscosity should be expressed after taking it's log. It's not as if any information would be lost that couldn't be recovered, but it would also make it clearer how insignificant small differences in the numbers are. Taking the numbers from the last example, log(350,000) = 5.544, while log(351,000) = 5.545 and log (349,000) = 5.543. Now instead of seeing a slight change in the third significant figure, the changes are in the fourth. Granted, I've seen people who would think a change in the eighth significant figure are significant, but most people would see the point I am making here.

  • I would double down on this argument not only because of the lack of significant figures, but also because of the wide range of viscosities that are observed. We've already seen 1 cPs, but the numbers can also go up into the billions of cPs or more for viscous polymers. As is is now, it is very rare that I ever prepare a plot or see another's plot with viscosity data that isn't logarithmic on at least one axis.
Answers to the qualitative viscosity questions: A liquid with viscosity twice that of water? I don't know of any right off hand. The closest I can think of is blood, which is at about 4 cPs in normal conditions. Olive oil is about 100 times thicker, while castor oil is about 1000 times thicker. And as for honey, Wikipedia lists it as between 2000 and 10,000 times thicker than viscosity.

So now that you have these numbers, does that help calibrate your internal scale, or are you still just as lost as before? I would be shocked if things are much better. Despite working with viscosity measurements on and off for the past 21 years, it's still just a number to me.

Friday, June 17, 2011

BPA Absorption from Receipts? I Don't Think So

Plastics News is reporting that Connecticut has now banned bisphenol A (BPA) in paper receipts. While I can understand the concern about BPA in baby bottles, the concern with receipts is a wholly different issue. Here are what I see as the differences:

Baby bottles, which can potentially leach BPA are in contact with milk and other liquids that are consumed by infants. If the BPA gets into the liquid, it can get into the infant. And since infants consume quite a bit a liquid in such a manner during their first years of life, and since they are so small, the exposure levels could be a concern. Scientific findings strongly suggest otherwise, but at least in this case, you can still see a straightforward path between source and exposure.

But compare that with receipts. The frequency of handling such receipts will be minimal, in many cases less than once a day (except for cashiers), the exposure period is for short time (until it is tossed or put in pocket) and the mass of the person is 10x to 30x larger, But more importantly, the receipts are handled by people's hands. Why did I emphasize hands? Because the skin on your hands is one of the least permeable areas on your body.

I'm not sure if transdermal patches drove the research in the area, but regardless, the variation of skin absorption has been studied. The picture below summarizes the results "Source: Percutaneous Absorption: Drugs - Cosmetics - Mechanisms - Methodology" and is from Chapter 5. This spread is called "regional variation" [1] in percutaneous absorption.You'll notice that palms are very low on the list, with only the forearms being less absorbent [2].

That the hands are so impermeable is something you probably already knew without necessarily being aware of it. For example, lots of people I know (including myself) have had poison ivy outbreaks all over their bodies, but never on their hands, even though hands are a very likely source for contacting the urushiol oils.

As long as people aren't taking their receipts and rubbing them all over their bodies on a regular basis, I'm already very suspicious about being concerned with this exposure route, and banning the material in this application amounts to little more than political grandstanding.

[1] The chapter starts by noting that the first occupational illness ever identified was scrotal cancer in chimney sweeps. The sweeps were coated head to toe with soot, but since the scrotum is the most transmissive region of the body, that is where the cancers began.

[2] Why are the forearms so nonabsorbent? I can see (evolutionary) advantages in hands being nonabsorbent since we they are our primary means of interacting with the world, but why forearms?

Thursday, June 16, 2011

UV Abosrption and Sun Protection Factors

With all the fanfare and emphasis on protection-of-the-general-public that they could muster, the US Food and Drug Administration announced this week that they are activating new regulations on sunscreens. Somehow I doubt that the new labeling will do anything to reduce the increases in skin cancer that are being reported, (people still smoke despite the ever scarier labeling on the packs), and capping the limit for the sun-protection factor (SPF) at 50 is not really doing any good for anyone.

The (photo)chemistry and physics of sunscreens is no different than what occurs in UV absorbers in plastics (except that they are applied non-uniformly over the body, whereas UV absorbers are either mixed into the entire polymeric matrix or applied as a uniform coating. Given that and knowing we do a tremendous a tremendous amount of work with here at Aspen Research on UV degradation of polymer and prevention of that degradation using UV absorbers, I'm surprised that I never looked into SPF's before. Digging into the matter, I was pleasantly surprised by how well the science behind the SPF has been worked out. A key part of the calculation is that the activation spectra of the skin [*] is included in the calculation of the UVB absorption. From Wikipedia (and confirmed elsewhere in the open literature), here is the activation spectra of skin for sunburn, along with the intensity spectra of sunlight, and the product of the two: This is then used in the following formula for calculation of the SPF:
\mathrm{SPF} = \frac{\int A(\lambda) E(\lambda)d\lambda}{\int A(\lambda) E(\lambda)/\mathrm{MPF}(\lambda) \, d\lambda},
where MPF(l)is the monochromatic protection factor - how much the transmission at each wavelength.

SPF is only calculated for the UVB spectra (280 nm - 315 nm), not UV A (315 nm - 400 nm). I imagine trying to patch together an activation spectra for UVA light would be challenging - not so much in preparing the spectra, but in trying to assess the relative impact of it compared to the SPF calculated for the UV B range. Bottles could be labeled with 2 SPF's, but that would be too confusing, wouldn't it?

[*] The activation spectra of a reaction is a description of how the kinetics change with wavelength. This is an extremely important concept that is often overlooked in most UV exposure testing. Most people assume that exposing a sample to shorter wavelengths will be fine for mimicking degradation in the natural environment. That only works for materials that absorb at the lower wavelengths. Unabsorbed photons do not lead to degradation, so in some cases, exposure to the wrong wavelengths will lead to completely erroneous conclusions about how well a part will survive. Always know your activation spectra!

Wednesday, June 15, 2011


The local newspaper had an opinion piece this last weekend on sustainability by a local writer, and while it does focus somewhat on local issues, it still has some interesting ideas sprinkled throughout it while it wanders all over the place.

I liked the expressed opinions, probably because they closely reflect my own. The piece takes a good shot at briging down the whole concept of sustainability, how it is probably a meaningless term now completely co-opted by marketers and businesses, even as there is this undercurrent in the article that it truly is worthwhile for us to not try and consume as much as possible while on this earth.

Some snippets:
"Does generating all your power on site -- however inefficiently -- really contribute to a thriving community that's built to last? Can a community be sustainable even if the economy on which it depends -- something largely out of a community's control -- doesn't sustain? Another problem, as [Environmental historian David] Worster points out--sustainable for how long? A year? A generation? Forever [?]...Few societies in human history have sustained beyond a few centuries."
(This hints at the idea I mentioned last week that the global optimum is not found by optimizing each sub-piece.)

And I like the irony of this one:
"Today, China and India are gambling on so-called unsustainable development--heavy use of water, coal and polluting industries -- to lift their people out of poverty. Paradoxically, that unsustainable step may lead to a more sustainable future."
I personally don't think that sustainability is possible for humans. It would require thinking with a long term perspective, a very long term perspective, an ability that we show less and less capacity for with each passing year.

Monday, June 13, 2011

Methane Generation from a Biodegradable Polymer

Once again we have a case of a press release overstating a research result. And that is rather sad, as the original research is rather interesting (at least at one level, as I shall explain).

As we all are well aware now, the creation and demand for biodegradable polymers continues to grow every year. While this is considered a good outcome by environmentalists and the general public, it is well known that most biodegradable material ends up in landfills, a buried tomb where the biodegradation that was originally desired for the product (conversion to CO2 and H2O) doesn't really occur since a landfill is generally lacking in O2. Instead of the complete oxidation reactions, incomplete reduction reactions occur, leading largely to the formation of CH4 (methane), potent greenhouse gas, far more potent than CO2.

There is a new report in Environmental Science and Technology (open access!) this month that look at this issue from two perspectives – that of the national overview of the landfills located in the US and how much methane that can/could/will generate, and then also looking at the degradation of specific components in the landfills. This was the part of the report that I thought was especially interesting. The big unknown is the generation rate for a landfill, not only in the present, but also in the future. Enter a Monte Carlo analysis to determine the sensitivity of the authors results to the assumptions. I was pretty impressed with the work that the authors put into trying to capture this and ensure that their results are meaningful.

From the small-picture perspective, the authors determine the degradation kinetics for 4 (and only 4) input materials, these being food waste, newsprint, office paper and a biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHBO) and found that the faster a material degrades, the more likely it is to produce methane, a hihgly potent greenhouse gas.

PHBO? Why this polymer, one that as far as I know isn't commercially available? (The article doesn't even state the source of the material that they tested.)

This is more than just a strictly academic questions, since PLA (polylactic acid) is actually being produced and consumed on a somewhat volumetric basis? And wouldn't the results be significantly different if PLA were being studied instead of PHBO? There certainly is reason to suspect similar results since PHBO and PLA are both polyesters, but PLA certainly has more oxygen per repeat unit than the PHBO does. Some data would be really helpful.

But more importantly, the researchers never overstep the bounds of their research. They a quite clear in their conclusions that they are only talking about 1 biodegradable polymer, not all biodegradable polymers.

Unfortunately, that is not what was being stated in the PR blurb and what is being discussed around the internet. To make a blanket generalization that ALL biodegradable polymers will produce so much methane as to be overall unfavorable is not a correct statement to make based on the evidence here. But to know that, you have to read the report and not just a the hype. (Quite a challenge, huh?)

Lastly, what is also not stated anywhere is that while CO2 is most certainly a powerful greenhouse gas, it has a short lifetime in the atmosphere compared to CO2. That only has merit if the amount of CH4 is decreasing over time - i.e., that no new material is being generated.

Friday, June 10, 2011

The Supreme Court Decides On Freebase Cocaine

I discussed sloppy nomenclature in polymers earlier this week. The PEG/PEO controversy is not so bad as to reach the Supreme Court, but those naughty chemists have been so sloppy that the high (sorry, had to throw that in!) court needed to step in, as happened in yesterday's decision. As I mentioned back in March when the case was first heard [*], the issue basically is whether or not "cocaine base", the term used in the law, is different than crack cocaine, a particular type of cocaine base. Part of the problem is that cocaine base is a redundancy - in a strictly technical sense, all "cocaine" is a base, unless stated otherwise, and yet the term "cocaine" by itself usually refers to the hydrochloric salt (which is the powder that people inhale).

As a result, the decision is rather boring reading of the justices all trying to parse the semantics and justify their particular parsing, all the while noting that the language is not clear.

So shame on you chemists! Let's start getting our bases and salts right so that Congress can get it right. No cutting corners, you hear!

Personally, this is all academic. I've never touched the stuff (that's a lie!) and having made nearly 50 orbits around the sun, I'm not going to start.

[*]...and we all had a good laugh at Justice Breyer for this comment:"People sniff it often, I guess, if it's a salt. And that's bad. And then there's a kind that's worse, that's freebase or crack, and that isn't a salt and it isn't a poodle and it isn't an acid."(emphasis added)

Have You Considered a Career in Plastics?

Some fun for a Friday. Not much to add here, it's just an artifact of an older time. The one line I really enjoyed was "Learn the hundreds of interesting phases of the plastics industry" Sorry about the poor image quality. The original is much clearer Source

Wednesday, June 08, 2011

It's a Bloody Good Mystery to Me

This is a strange, but interesting report. Prof. Rongjia Tao of Temple University has found that exposing blood to a 1.3 Tesla magnetic field for about a minute reduces the viscosity of blood by about 20 - 30%. The magnetic field forms long chains of the red blood cells, and if these are aligned with the direction of flow, then the viscosity drops. I'm not expert on blood, but I do know that in general, thick blood is far more dangerous than thin blood, so being able to thin it effectively without the use of drugs could be a real advantage in certain situations.

This is what unexposed cells look like: and this is what the exposed cells look like: At first glance, the whole idea of exposing blood to a magnetic field may seem far-fetched, and in reality it could not be done effectively just by bringing the patient into the magnetic field. Blood is flowing every which way in the body and nothing would be aligned too effectively. But I still can see real potential here. It is very common for blood to be withdrawn continuously from the body, flow through a thin channel and then be returned to the patient such what happens all the time in dialysis and heart-lung machines. In such a situation, there would be ample opportunity to apply this technique to the blood while it is external to the body.

Now all of this is exciting, but here's what really caught my eye, and unfortunately, is left unexplained in the full article. After the field is removed, the blood needs about 2 - 3 hours to fully recover it's normal viscosity.


Why such a long relaxation time for such a low viscosity material? I am really at a loss to explain this, and somewhat strangely, the article doesn't even really seem to think that there is anything unusual about it as they make no mention of this hysteresis. Does it really take that long for the magnetization of the iron to relax at body temperature, or in the same vein (heh, heh), does it take that long for the thermal energy to drive the cells apart and negate the magnetic attraction? Is there now some stickiness between the cells that keeps them together that wasn't there before? Is the magnetic field interacting with more than just the iron in the blood? I am greatly puzzled about this "thixotropic" behavior, and if anyone has any ideas, please add your comments.

And of course, the devious retired-bicycle-racer-who-now-gets-fat-in-the-winter in me wonders if how long before such a device is used to improve athletic performances. It won't help you win a long event such as the Tour de France, but for a short track event (200m sprints for instance), it could give you an edge. Get your blood all magnetized before your event, go onto the track and let the low viscosity fluid run all through your veins while you pump out a sub-10.5 record. By the time the lab could even look at your blood, the viscosity would have return to normal. How is anybody ever go to catch that short of quarantining the athletes before a competition (and that approach would never fly).

A New Journal in Polymer Science

The American Chemical Society has announced that they will soon (January 2012) start publishing the journal Macro Letters".
"This new rapid-publication journal, available exclusively online, makes it possible for authors around the world to publish their urgent, peer-reviewed findings in all facets of polymer science in record time, within four to six weeks of submission."
Just remember, these are for urgent results, the kind that keep our industry moving and changing weekly. I think "Macromolecule Letters" would have been a better title - the existing title makes me think of either 1) really long letters, such as something written by Proust or 2) really LARGE letters.

Tuesday, June 07, 2011

A Green Polymer?

While more and more nylons are becoming eligable for production from bio-based feedstocks (sebacic acid, an ingredient for nylon 66 seems to be popping up everywhere), nylon 11 is the only one that is held out as being currently produced from a renewable source - castor oil.

The only problem, is that getting from the oil (let alone the bean and the non-greenness associated with it's production) is quite a series of steps. Consider this:
"Castor oil is converted to methyl ricinoleate by treatment with methyl alcohol. Methyl ricinoleate is pyrolysed at high temperature yielding heptaldehyde, methyl undecylenate and a small amount of fatty acids. Methyl undecylenate is hydrolysed to produce undecylenic acid. When undecylenic acid is treated with hydrogen bromide in a non-polar solvent in the presence of peroxide, reverse Markownikoff addition occurs and the main product is x-bromoundecanoic acid. This is then treated with ammonia to give x-aminoundecanoic acid, which is a crystalline solid. Aminoundecanoic acid is the starting material for nylon-11."

So after getting the oil, you add 1) methanol, 2) heat, 3) a purification step, 4) water, 5a) HBr and 5b)an unspecified solvent and 5c) peroxide, and finally 6) ammonia. But after all that, you're still not done - you still have to polymerize the aminoundecanoic acid and remove the water.

And somehow this is considered a renewable polymer!

As we all learned in multivariable calculus, you don't find a global optimum by optimizing each individual variable, you optimize the systems as a whole.

Monday, June 06, 2011

Is it PEG or PEO?

Polymer nomenclature tends to be confusing at times, largely I think of it being created faster than it can be standardized. Polyvinyl alcohol is my favorite misnomer, as it implies that the polymer is made from the polymerization vinyl alcohol [1]. But another one that is almost as bad is the whole polyethylene glycol/polyethylene oxide dichotomy. If you are not aware of it, let me illustrate.

Here is the structure of polyethylene glycol (PEG):

and here is the structure of polyethylene oxide (PEO):

If the difference isn't apparent to you, don't worry, there isn't one. The only difference between the PEG and PEO is molecular weight, which is set at the totally arbitrary limit of 20,000 Daltons. Below that limit, you have PEG. Above that limit you have PEO [2].

Why the limit? I'd love to know. Somebody at some point in the past made the decision for the difference [3] and we are stuck with this duality for all eternity.

[1] Vinyl alcohol doesn't exist. It undergoes a keto-enol isomerization to form acetaldehyde. The polymer is actually made from the hydrolysis of vinyl acetate, replacing the acetate side chains with hydroxyl groups.

[2] What if you are at 20,000 exactly? Then what?

[3] I'll give to 100-to-1 odds that it was a marketer.