Category Archives: Science

Nobel Prize Buzz

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It’s that time again. Time for the buzz to start about who gets a trip to Stockholm.  My favorites, in no particular order, are- Bergman, Grey, Whitesides, Kagan, and Mislow. It is a pity that Al Cotton passed on before taking his ride to Sweden.

Naturally, my guess will be wildly off-base owing to my complete ignorance of some seminal work on nano, bio, metalloenzymatic, mRNA, photolabile, surface active, quantum tunneling, neutron activated, antiviral, ionic liquid, quasi-xtal work that has been thrumming along in the basement of Princeton university since Ike was president and known only to 8 people.

Thermal Decomposition of Sucrose in Nitrogen Atmosphere

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Below is a thermogravimetric (TG) scan of commercial grade sucrose. Over the course of the experiment, the compound is quite stable to decomposition to the gas phase under N2 up to the onset temperature of ~226 C. This is indicated by the constant temperature line leading up to the onset.  Above 226 C it begins to evolve gas or aerosols.

The furnace temperature ramp is 10 C/minute, the purge gas is nitrogen, and the crucible is platinum. The software that presents the data determines an onset and offset temperature by intersecting lines extending from the slopes of the lines at points chosen by the operator. In this way, the computer “squares” the broad curves and reports a temperature at that point.

Not shown is the % mass loss; from ambient to 500 C the sample lost 78.55 %. The slope of the curve from the onset to offset temperature is 0.69 %/deg C. Multiplying by 10 deg C/min, the cook off rate is 6.9 wt %  per minute in the temperature ramp. An isothermal run could be performed to look at behaviour under constant temperature.

The value of information presented by this analysis is somewhat limited to the relevance of conditions in the crucible. TGA can be a big help in determining the onset and extent of dehydration or other decomposition transformations. It can easily detect the ability of a material to sublime as well.  And, it can provide information to process chemists and engineers regarding certain aspects of temperature stability and thermal safety.

 

Fire Extinguisher Training

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Everyone should have a chance to use a fire extinguisher on a real fire. The trouble with this idea is that the annual discharge of fire extinguishers is expensive, training fires can be problematic, and the discharge from the extinguishers can leave a big mess.

I had the chance recently to undergo annual training with a new controlled fire training system made by BullEx. I’ll admit to being skeptical at first. It seemed awfully contrived and … safe. But watching the tenderfoot office staff line up with their backup buddies to use pressurized water to put down a controlled and “adjustable” fire, I finally came around and had to agree that the system has considerable merit. For us, the system pays for itself in 1 year of training in terms of retiring dry chemical recharge costs.

Most would agree that a fire extinguisher is fairly simple to use. What seems to be the hard part for many is overcoming the uncertainty about whether they should use the extinguisher and under what circumstances. While the simulator does not produce smoke, obnoxious fumes, and there is no dust cloud from a dry chemical extinguisher discharge, the system does a good job of building confidence in people who may be a bit timid.

A Life in Industrial Science

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There are many ways to live a scientific life in chemistry. The obvious examples are the lives of chemistry faculty. A chemistry prof’s time is split between teaching, managing a research group, grant writing, committees, giving seminars, academic advising and, oh yes, a home life. 

In industry, the life of a scientist can be split between several layers of applied research, management of a budget and directly reporting staff, occasional patent work, meetings, writing reports, and if there is a spare minute, leafing through a journal.

I could have never anticipated the job description that I now hold. The specifics aren’t important for the purpose of this essay. What I want to describe is the extent to which I am constantly juggling numerous diverse, often intractable, open-ended tasks. It dawned on me recently that my job description sets me up for a career of dealing with thorny problems that few want and could or would handle.

Is this shameless self-admiration? No, it’s really a kind of lamentation. It would be nice to do something straightforward now and then. I used to do the advertising. Then we got back the C&EN survey results. I don’t do the advertising anymore. I’d like to meet a few of those rotten commenters … \;-)

Because I share office space with the accounting group, I have the chance to lunch and banter with the bean counters. It doesn’t take long to realize that theirs is a life of well defined tasks with built in cross-checks and monthly cycles. These accountants have their work cut to size and funneled to them by highly formalized and structured norms. Their job is to enforce consistency and eliminate surprises. They express discomfort and fear near the boundaries of their knowledge.

In contrast, scientists are people who seek out the boundary waters of knowledge and actually set up camp there. A scientist is someone who finds a way to acclimate to a life of uncertainty. A scientist knows that ignorance and uncertainty can be ground down with hard work and a bit of luck. Luckily for me, dogged persistance can partially make up for the lack of genius.

But despite the high minded platitudes about the endeavor of science, I’ve come to appreciate washing glassware and cobbling together a plumbing solution to a problem with an apparatus exactly because it is so concrete. Unlike molecules, I can actually see the results of my plumbing handiwork of compression fittings, steel tubes, and rubber hose. Sometimes it is nice to leave the abstract behind and make something simple but sturdy.

A Case of the Vapors

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There is an interesting debate happening in the weather and climate modeling wing of the blogosphere. Seems that over at Wattsupwiththat someone has pointed out the significant part water vapor may play as an absorber of solar energy. All you have to do is look at the absorbance spectrum of water vs CO2 and you’ll see that the game is suddenly more complex than the incessant drum beating about CO2 would suggest.

There are a number of good websites on weather and climate out there. Rabett Run seems well centered in terms of the science.  If you are interested in the level of play happening in the real, behind the scenes debate, check out the references to Kirchoff’s law.  Physical meteorology is at the center of the whole debate. Assumptions about the applicability of certain laws, assumptions about the value of key variables, and other details of equation building can drive the nature of the conclusions. Planetary atmospheres are really quite complex!

I think it will be several more solar cycles before the right modeling assumptions shake out.

Fast Food Munching Criminals Leave Corrosive Fingerprints

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University of Leicester, UK.  John Bond, a reseacher at the University of Leicester and consultant to the Northamptonshire Police, suggests that criminals who consume fast foods leave fingerprints that are corrosive. Dr. Bond says that enhanced levels of salt in processed foods can lead to sweaty fingerprints that are more corrosive to metals.

Dr Bond said: “On the basis that processed foods tend to be high in salt as a preservative, the body needs to excrete excess salt which comes out as sweat through the pores in our fingers.

“So the sweaty fingerprint impression you leave when you touch a surface will be high in salt if you eat a lot of processed foods -the higher the salt, the better the corrosion of the metal.”

Dr. Bond went on to say that there was an “indirect link” to obesity and the chances of being caught in a crime. Bond says that corrosion due to fingerprints may be helpful in the tracking of terrorists whose bombs are fragmented from the explosion.

Destroying Munitions with Solvated Electrons

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Blundering through the patent literature I took a wrong turn and tripped over a patent that claims an interesting use of ammonia solutions of electrons. The patent, US 6080907, is assigned to Teledyne Commodore and teaches a method that uses ammonia as a fluid metal cutting medium for the safe destruction of bombs and the explosives inside. The inventor claims that ammonia is superior to water as a cutting fluid. Apparently Teledyne employs a few chemists because it dawned on someone that ammonia will also dissolve certain metals and provide a means of conveyance for a reducing agent to enter the bomb casing and reduce the nitro groups on the explosives. It is a clever idea. A new use for the Birch reduction.

 I wonder if it is in operation?