Chemistry Blog

Feb 15

Android Spectroscopy


I was jealous when I saw Joel write about his boss using his iPhone’s light source for experiments (finally, a really useful science iphone app). I knew I had to one-up him for no other reason then I am a Google Android user. Below is a video of an app I made; the app will scroll through the visible spectrum. In the video the glass contains red wine.

During the video you can see the wine absorbing blue light when the camera pans over the glass for the first time. Next time it pans over the red wine the light is green and still not transparent, but as the light was turning yellow the solution became more transparent. By the end, the light was red and it transmitted through the wine just fine.

If I had an other Android phone on hand I probably could have made a quick and dirty visible spectrometer.

Mitch

Feb 13

Biology professor allegedly involved in shooting


Suspect in UAH shooting - credit Huntsville Times, Dave Dieter

News broke this afternoon that there was a shooting at the University of Alabama in Huntsville’s Shelby Hall. It took me a while to find that this is (among other things) the home of UAH’s chemistry department. While CNN hasn’t filled in the details, the Huntsville Times already has reported that biology Professor Amy Bishop was taken into custody and her husband has been detained for the deaths of 3 faculty members and the wounding of 3 others.

While stunning and tragic, this would not have rated a post except for the alleged reason for the shooting: denial of tenure. According to the New York Times:

WAFF, the NBC affiliate in Huntsville, quoted university officials as saying the professor began shooting after learning at the faculty meeting that she was being denied tenure…

Dr. Bishop had told acquaintances recently that she was worried about getting tenure, said a business associate who met her at a business technology open house at the end of January and asked not to be named because of the close-knit nature of the science community in Huntsville. “She began to talk about her problems getting tenure in a very forceful and animated way, saying it was unfair,” the associate said, referring to a conversation in which she blamed specific colleagues for her problems.

Wow. Denial of tenure must be crushing for an assistant professor, especially since the process must seem protracted, random and unfair (at times). The really surprising detail is that (allegedly) she brought a gun; that’s an indication of a willingness to use violence and a certain level of forethought as to the potential outcome of the meeting. (CORRECTED: see update below.) Academic science is high pressure indeed.

My (our) thoughts are with the families of the victims.

UPDATE: From the AP:

University spokesman Ray Garner said Saturday that the professor, Amy Bishop, had been informed months ago that she would not be granted tenure. He said the faculty meeting where she is accused of gunning down colleagues was not called to discuss tenure.

Feb 12

This Message Will Self-Heal in 3, 2, 1…



Cassandra Fraser

Recently, Cassandra Fraser’s group reported on a very cool property, reversible mechanochromic luminescence, observed in an easy to make material.[JACS] The molecule of interest is the difluoroboron complex of avobenzone (BF2AVB), that UV absorbing molecule in your sunscreen minus the boron and fluorines.

In broad general language, mechanochromic luminescence describes the ability of some materials to change colors after scratching under UV light. The image below shows BF2AVB coated on weighing paper (A), a cotton swab is used to write “Light” (B), the surface is hit with a heat-gun (C), the surface is ready to be written on again with a cotton swab (D).

The image brings up all kinds of creative ways to write secret messages, especially as the letters will fade over time even without using a heat gun. But before the CIA intelligence wonks in the audience get ahead of themselves the material doesn’t seem to be completely reversible at room temperature without annealing.

…even a small mechanical perturbation, such as a slight touch with the tip of a cotton swab, changed the green-blue BF2AVB film emission to yellow. The yellow emission gradually reverted back to green again at room temperature, with much faster recovery at elevated temperature. The written regions were no longer readable after annealing.



The field has, in short order, gotten tantalizingly close to a 100% reversible mechanochromic luminescent material at room temperature. Congrats!

Link to article: Polymorphism and Reversible Mechanochromic Luminescence for Solid-State Difluoroboron Avobenzone

Sam covered one of the first entrants to reversible mechanochromic luminescence a year ago: reversible mechanochromic luminescence is cool

Mitch

Update and Correction: Cassandra Fraser has corrected me, apparently the wording of the paper was just awkward to my ear, the material is fully reversible at room temperature!

Feb 10

How Water Freezes Lower on a Negatively Charged Surface


I first heard this on National Public Radio and then I searched for it. In short, David Ehre, Etay Lavert, Meir Lahav, and Igor Lubomirsky report in Science, (Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials) water freezes at a lower temperature (-18°C) on the negatively charged side of a lithium tantalate plate with a strontium titanate film than on the positive side (-7°C, and -12°C uncharged).

Is this unique or is this a manifestation of something in our standard introductory organic chemistry textbooks? I thought it was the latter. Let me explain how.

For the purpose of thinking about this problem, let us assume the metal surface is simply a flat charged surface, without contour. If the surface has a negative charge, then the water should be attracted like a flagpole. One hydrogen should be anchored to the surface of the metal at right angles and the other hydrogen could spin about that axis with the flag hydrogen at 105°. It should not be surprising that this configuration should not be as good of a surface as one with greater rigidity.

If we compare with the positively charged surface, then both pairs of non-bonded electrons should be anchored to the surface and locking the hydrogens in a fixed position. This should limit the degrees of freedom and enable crystal growth.

For those that may be wondering where this is found in your textbook, it may not be there. The negatively charged surface is the one that seemingly will have the most important stereochemical constraints and information in a textbook. The analogy I was comparing is the stereochemical restrictions of proton transfer reactions. In that context, the angle between a proton and donor-acceptor electron pairs in a hydrogen bond is usually 180°. One can find smaller bond angles in intramolecular proton transfer reactions, such as the decarboxylation of a beta-ketoacid or a Cope elimination reaction of an amine-oxide as six and five-membered ring examples.

You may also encounter a … transition state which transfers a proton via a four-membered ring. While this mechanism is present in some textbooks, I am troubled by a lack of precedent for this proton transfer. In a normal hydrogen bond, the preferred bond angle is 180°. Variations from 180° are commonly found in six and five-membered rings …

While the four-membered ring is expedient and avoids a zwitterionic intermediate, I am skeptical sufficient experimental data exists to support it. In the normal hydrogen bond, the electron-electron repulsion forces the nuclei to be linear.  While smaller angles are present in six and five-membered rings, a continued decrease in bond angle increases the electron-electron repulsion exponentially as predicted by Coulomb’s Law. This could be compensated for with a large nucleus…. A larger nucleus can attract electrons and mitigate their repulsion. However, I have resisted writing any examples of proton transfers via four-membered ring intermediates. [A Handbook of Organic Chemistry Mechanisms, p 65]

I could have drawn a model with two attachments points for water. That would probably look better if a plane charged surface is present rather than several pairs of electrons. If a two point model were to be present, then another model for the melting point difference is needed.

P.S. this is my first post here. As I often seem to think of something bleeding edge, not obvious, heretical, or downright wrong, I hope if there were any comments, this is just an idea. I may change my mind tomorrow.

Feb 08

Geoengineering Scientists and Congress



(From Left to Right)
Dr. David Keith
Dr. Philip Rasch
Dr. Klaus Lackner
Dr. Robert Jackson

Geoengineering is a wonderful example of taboo science. Most people would fall within 2 camps. Camp 1 considers geoengineering with disdain as it mucks with the natural environment. Camp 2 probably wouldn’t want their government involved in planetary climate control. With those entrenched camps where do scientists fit in?

Scientists were called as witnesses before The House Subcommittee on Energy & Environment last week in regards to geoengineering. The witnesses invited were…

  • Klaus Lackner (Geophysics,
    Earth and Environmental Engineering): Covering CO2 sequestration
  • Robert Jackson (Biology): Covering Biological and Land Strategies to lower CO2
  • Philip Rasch(Atmospheric Science but a chemist by training): Calling for a Manhattan project type approach to researching geoengineering
  • David Keith (Chemical and Petroleum Engineering): Mainly advocating that some sort of global policy towards geoengineering needs to be developed. The most sane and coherent witness; scientists don’t usually fair well before politicians.

So why care about taboo science? The simple matter is that it would cost 1-2 billion a year to return the planet to pre-industrial levels of temperature, assuming they use cheap sulphates to do the job. This means any number of nations, frankly any wealthy cohort of industrialists, can take climate control into their own hands.

Since geoengineering is a delicate subject to broach to the public, transparency is crucial and wasn’t loss on the chairman Brian Baird (D-WA). Congressman Baird mentions how some citizens believe their government is placing psychotropic drugs in jet fuels, the so called chemtrails and remarked “…legitimate scientific research [in geoengineering] must not get tied up in these kind of things.”

However, all the scientists were taken aback by Randy Neugebauer (R-TX), my favorite exchange was the following.


Randy Neugebauer (R-TX)

Randy Neugebauer, “What percent of the atmosphere is CO2?”
Scientist, “390 parts per million”.
Randy Neugebauer, “Less than one tenth of one percent…This tiny minuscule amount…[can’t] be more important factor in our climate than solar activity”.

I’m not even sure where to begin to broach such a deep misunderstanding of climate change. I would have mentioned to Mr. Neugebauer that he would be dead if that minuscule amount of CO2 was removed from the atmosphere, as all plants would die followed by animals in short order. The concept of small amounts having huge impacts in large dynamic systems is an important lesson to teach, even more so to do it dexterously. These types of exchanges went on for some time. I’m left wondering why Randy Neugebauer is even on the Subcommittee on Energy & Environment in the first place.

The ranking Republican, Bob Inglis (R-SC), had this to say in his last remarks, “I believe in a basic role of government is to do basic research, its an important function that we do.” It is nice to know that basic science research is appreciated by both sides, even though there is always a rogue member in every committee.

Press Release: Subcommittee Examines Geoengineering Strategies and Hazards

Mitch

Feb 04

Chemical Journalism


For those with an interest in journalism and time this summer ACS is offering a summer internship in the C&EN newsroom. Deadline is Feb 22nd.

Chemical & Engineering News, the weekly newsmagazine of the American Chemical Society, seeks an intern for our Science/Technology/Education department for the summer of 2010.

C&EN reports current events in the chemical enterprise, including recent advances in research, education, industry, funding, and regulatory policy. C&EN reaches all 154,000 members of the ACS each week, and its online edition receives more than 13 million page views per year.

The candidate should be a highly motivated student or recent graduate with demonstrated interest in science writing and at least a bachelor’s degree in chemistry or a related field. The intern will have a chance to write bylined news and feature stories for publication in C&EN. We offer a $1500 monthly stipend for three months. The intern ideally will be based in our Washington, DC, headquarters; however, exceptional candidates unable to relocate may be considered. Starting and ending dates are flexible.

Contact Amanda Yarnell for more information about this year’s internship.

Link: C&EN Internships

Update: There is also an associate editor position available.

Mitch

Older posts «

» Newer posts