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Week of 28 January 2008


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Monday, 28 January 2008
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08:36 - I keep getting stuff done, but my to-do list keeps getting longer and longer. This weekend, in addition to the laundry and other usual stuff, I got wire shelving installed in the pantry cabinet in the kitchen and on the back of the door into the dining room. Continuing the shelving theme, I got most of the shelves installed on the end wall of my lab and did some clean-up and reorganization there.

One of my subscribers from earthquake country emailed me and asked if I planned to include a wire or something across the front of the shelves to keep the bottles from falling off. I thought about it, but I think they'll be fine. The shelves are 3.5" wide, plus a half inch gap between the back edge and the wall. I've secured each bracket (two brackets per 4-foot shelf) with three 1 5/8" drywall screws into the studs. They're rock-solid. Each shelf is secured to its brackets by a screw driven up through a hole in the bracket into the shelf.

Most of the bottles that'll go on the shelves, and all of the bottles on the higher shelves, are 4-ounce amber glass bottles that contain at most 100 mL of (typically) pretty dilute solutions. The bottles are 2" diameter, so there's plenty of space on the shelves.

Anything strong enough to knock those bottles off the shelves would give us a lot more problems than worrying about the bottles. I think the strongest earthquake we've had in recent times is about 3.5. We do have tornados, but again if we get nailed by something that bad we'll have more important things to worry about.

Today, I'll finish installing the shelves in the lab and do more clean-up down there. I need to get it cleaned up enough to use as a set to shoot some videos.

I also need to do some lighting and sound tests, not to mention figuring out how best to shoot closeup video of reactions in test tubes and so on.

I also need to come up with an alternative for a teleprompter. Most of the narration will be voiceover, but I'll do some talking-head shots. For those, I have a couple of ideas. I may use the traditional method: print the dialog in large type on both sides of sheets of paper, and have Barbara hold them up as I read, dropping each sheet as I finish it. Alternatively, I may just run a length of stiff wire between the cabinets on either side just above the level of the camcorder lens and use clothespins to suspend the dialog pages from it.



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Tuesday, 29 January 2008
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10:37 - I finished installing shelves in the lab yesterday, so I now have 24 linear feet of additional shelf space. That frees up a lot of cabinet space.

The top three shelves are spaced to hold the four-ounce (118 mL) amber bottles I use for most bench reagents, 22 per shelf. When I need, for example, some potassium thiocyanate, it's much more convenient to measure the required amount of potassium thiocyanate solution than to weigh the solid chemical. All of the bench solutions are made up to 0.01 M accuracy, which is sufficient for nearly anything I'll do.

The fourth shelf has the same spacing as the first three, but contains stuff like acid-base and redox indicator solutions, special reagents like Dragendorff, Marquis, Scott, and Wagner reagents (all for alkaloid tests), and so on. The fifth shelf is spaced to hold the one-pint (473 mL) bottles that contain bench solutions of things like dilute acids that I use more frequently or in larger quantities. Finally, the sixth shelf has still wider spacing for storage of bulk chemicals like 1 kilogram bottles of copper sulfate, sodium hydroxide, etc.



I got email yesterday from Dale Dougherty, the publisher of MAKE. He'd read the recent articles about high levels of mercury in sushi, and wondered if there was any practical field test for mercury. I replied:

Hi, Dale

Alas, no, that's not possible.

The problems are that mercury is toxic at unbelievably low levels and that it is a cumulative poison, which is to say it isn't excreted. Accordingly, the allowable levels are set so low that there's no chance they could be detected by any wet chemistry test with a sample of any reasonable size.

I was pretty sure of my facts, but just to be certain I ran them past Paul Jones. His response was, "Maybe you could use a wet chemistry test if you had an entire 500-pound tuna for your sample, but otherwise you'd have to use instrumental tests."

Mary Chervenak points out the Reinsch Test for mercury (which also produces a positive for several other heavy metals). You dissolve the sample in dilute HCl and put a copper strip in the solution. Any mercury present plates out on the copper as a silvery mirror. The trouble is, if enough mercury is present to produce a visible mirror with the Reinsch test, that sample has enough mercury in it to poison everyone in a radius of several blocks.

Dale replied, sending me a link to this site. To which I replied:

Holy Cow! Someone whose saliva or urine tests positive with this kit is a walking dead man. Again, one of the problems with heavy metals in general and mercury in particular is that they bind tightly in the body and aren't excreted. If your pee tests positive with this kit, you have so much mercury in your body that you might as well just lie down and stop moving.

Same deal with food samples. If you get a positive test, there's enough mercury in that sample to poison a lot of people. If you get a negative test, that's no indication that the sample is safe to eat.

To give you an idea of just how little mercury is hazardous, I just checked the numbers on allowable mercury intake, which the FDA says is six micrograms per day. In other words, the gram or so of mercury in a typical thermometer is enough mercury to match the allowable maximum for an entire city of 167,000 people.

If I get a spare moment, I may do the Reinsch Test just to determine the threshold level of mercury needed to provide a visible mirror. My guess is that it'd take at least a milligram of mercury in the sample, which is the maximum permissible daily intake for 167 people.

While Mary and I were talking about the Reinsch Test, she mentioned that she'd bought a novel for Paul that I might like. That got us talking about books, and I complained that I don't have time nowadays to read as much for enjoyment as I'd like. I seldom finish even one novel a day now, and sometimes I spend two evenings on one novel because much of my evening reading time is occupied reading for work rather than for pleasure. Mary said that wasn't surprising, since I'm now doing two full-time jobs; writing books and doing the equivalent of a graduate chemistry program. I hadn't thought about it that way, but she's right. As usual.



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Wednesday, 30 January 2008
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08:38 - More on mercury testing. When I talked to Paul Jones about this, one of the first things he asked was, "can you do a flame test?" I replied that that probably wouldn't work with a real-world sample, because the mercury emissions would be swamped by emissions from other elements, particularly sodium. (If there's any sodium at all in a sample, the bright yellow sodium light overwhelms any other colors present.)

A little background. When atoms absorb energy, electrons are boosted to higher orbitals (energy states). The atom divests itself of that additional energy when the electron drops to a lower orbital. The excess energy is emitted as a photon at a specific wavelength. Accordingly, each element has a specific characteristic spectrum, which consists of lines of specific colors, and can be thought of as a "fingerprint" of that element. In the visible spectrum, mercury produces lines at 435.8 nm (violet-blue), 546.1 (green), 577.0 (yellow), and 579.1 (yellow).

If you vaporize a sample, say in a gas burner flame, and examine the light produced with a spectrometer, you'll see lines at those wavelengths if mercury is present in the sample. Of course, unless the sample contains nothing but mercury, there'll also be a lot of other lines that represent copper, sodium, or whatever other elements are present in the sample. But if lines are present at those wavelengths, you can be sure that mercury is present in the sample, whatever else also happens to be present.

Of course, to see the lines you need a spectrometer. If you've ever seen sunlight split by a prism into a rainbow, you understand the basics of how a spectrometer works. Instead of a prism, a spectrometer uses a diffraction grating to split the incident light into its component wavelengths. That spectrum is displayed against a scale so that you can determine the wavelength of each line. By comparing the wavelengths present against a list of the wavelengths produced by each element, you can determine which elements are present in the sample.

The problem is that flame spectrometers aren't cheap. Or so I thought, until I started looking around yesterday. I knew I could buy a diffraction grating for a couple of bucks. That would produce line spectra, but without calibration those spectra would be useless for identifying specific elements. Then I happened across this.

Imagine that. A $25 flame spectrometer. Well, you have to supply your own flame, but that's easily addressed. But the important part is that it provides calibrated spectra that can be used to identify specific elements in a flame. The sample images give you an idea of what line spectra look like. Hydrogen, at the top, clearly shows the H-alpha and H-beta lines. Sodium, in the middle, clearly shows the intense yellow lines characteristic of sodium. (The image at the bottom, also labeled "sodium", isn't.)

This little $25 device may look like a toy, but it's actually a serious scientific instrument. Obviously, it's nowhere near as sensitive or accurate as the $25,000 flame spectrometers found in professional labs, but it'll serve for our purposes. So I ordered one.

I'll use it in the home forensics lab book to illustrate how flame spectroscopy is used in forensics investigations. And, who knows, some of the young people who get their first experience with flame spectroscopy in their home forensics labs may in ten or fifteen years be using those $25,000 flame spectrometers in real forensics labs.



11:00 - Hmm. John Edwards just announced that he's dropping out of the race for the Democratic nomination for president. That leaves them with two candidates in the running, neither of whom is electable. Clinton is so intensely hated by considerably more than half the electorate that she has no chance to win a majority of the popular vote, let alone the electoral vote. And what are the chances that a man named Barack Hussein Obama could ever be elected president? Unless Ron Paul turns out to be the spoiler.

Things are likely to be interesting in November. The Democrats will run Clinton or Obama, it doesn't matter which. The Republicans will probably run McCain, who is at least electable. And I think it's very likely that Ron Paul will run as an independent. If so, he'll likely hurt McCain more than the Democrat candidate, possibly throwing the election to the Democrats.


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Thursday, 31 January 2008
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08:53 - It's nice to know that my journal page is occasionally of some practical use to readers.

From: Steve Sanders
  To: Robert Bruce Thompson
Date: Wed Jan 30 23:35:46 2008
  Re: Thanks for Saving Me A Service Call

Bob,

Our gas logs have not been working for the past few days and it has been cold (single digits F in the am) in the St. Louis area. The pilot light would come on, but it was a more yellowish flame and wouldn't stay lit.

Tonight, I did a Google search on "gas logs won't light" and one of the hits I got was www.ttgnet.com/daynotes/2002/2002-49.html.

I looked at your site, which I have been following since you started, and read what the service technician told you on 9 December 2002. I used a straw to blow the pilot light area clean. I then lit the pilot light. There was a strong, blue flame that stayed lit. The logs then fired up.

Thanks again. You saved me a few bucks.

It's always interesting when, from the entire Internet, a Google search turns up what one is looking for on a site that one regularly reads. I had the same experience a few years ago when I was trying to get my sister-in-law's Brother MFC-4800 printer running under Xandros Linux. The first hit that Google turned up for her printer model was one of Brian Bilbrey's journal pages. Until that moment, I had no idea that Brian owned that printer model.


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Friday, 1 February 2008
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09:01 - UPS showed up yesterday with the spectrometer, so I spent some time playing with it. It works as advertised, although it's a bit finicky about eye positioning. Last night, after we walked the dogs after dinner, Barbara and I spent a few minutes looking at different light sources--an incandescent lamp, a standard fluorescent tube, a compact fluorscent bulb, a streetlight, my computer LCD display, and so on.

It's pretty neat seeing the differences in the continuous spectra of some of those sources and the emission lines on others. For example, I just looked at a white area of my LCD display. There are three distinct lines, a broad, fairly dim blue line centered on about 490 nm, a bright green line at about 546nm, and a bright red at about 611 nm. There's also a much dimmer but sharp blue line around 436 nm, and a quite dim yellowish line around 578nm. Obviously, mercury is present in the LCD backlight. Moving the spectrometer over to the CFL in my desk lamp shows an identical spectrum, so it's clear that the LCD backlight uses exactly the same technology as the CFLs.

Continuous spectrum light sources are also interesting. Yesterday, I pointed the spectrometer at a brightly lit cloud. (Never point any optical instrument directly at the sun, which can blind you in an instant.) There were no lines visible, just a continuous bright rainbow from deep red on the left to deep violet on the right, with the brightness gradually tapering off at both ends. I'm sure the actual brightness doesn't taper off. It's just that my eyes lose sensitivity at the extreme ends of the visible spectrum.

When I pointed the spectrometer at an incandescent bulb, the difference was obvious. The spectrum was continuous, but not equally bright across the range. The left side of the spectrum, the reds and yellows, was very bright. The greens in the middle were a bit dimmer, and the blues much dimmer still. The violets were almost invisibly dim. It's obvious why incandescent lighting appears yellow-orange. There just isn't much green being emitted, and even less blue.

To get true full-spectrum light from an incandescent bulb, they'd need to boost the temperature of the filament from the 3200 K they use now to about 5500 or 6000 K. To do that, they'd have to replace the tungsten filament with some sort of ceramic, I suppose. Either that, or settle for a very short bulb life.



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Saturday, 2 February 2008
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00:00 -



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Sunday, 3 February 2008
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10:20 - Dinner with Paul and Mary last night.

Paul is getting ready for a working trip to Hawaii, where he'll be harvesting sea slugs as a part of his current project. Paul is an organic chemist with special expertise in photochemistry. I'm probably not getting this quite right, but apparently Hawaiian sea slugs consume algae and incorporate the chlorophyll, which remains photosynthetically active in the sea slug's body. I'd always thought that only plants used photosynthesis, but apparently there a few animals that do so, and Hawaiian sea slugs are one of them.

I suggested to Paul that he could save money by using common ordinary New Jersey sea slugs, but he claims there aren't any sea slugs in New Jersey. Furthermore, by an incredible coincidence, the types of sea slugs that Paul needs for his work are found only in resort areas around the world, so he has no choice but to spend lots of time at one or more of these resorts. I told Paul that I believed him, but thousands wouldn't.

As always, I learned something during the dinner conversation. This time, it was that the super bowl is being played this evening, although I still don't know which teams are playing or why I should care. Also as always, the conversation was very wide-ranging, from politics and sports and chemistry to methods for reducing the likelihood of eclampsia and the recent news articles on human parthenogenisis.

The pope ain't gonna like it, but it seems likely that before long lesbian couples will be able to be the natural parents of children for which one provides the ovum and the other the sperm, produced from stem cells in her bone marrow. Of course, since the two female parents have only X chromosomes, all children conceived by such couples will be female.

Male couples will be able to do the same thing, assuming they can find a host mother. Children conceived by two male parents will be one quarter female (XX), one half male (XY and YX), and one quarter monsters (YY).

Perhaps most intriguingly, there'll be nothing to prevent one person from contributing both ovum and sperm. I expect that religious people and politicians will fight that idea tooth and nail, presumably on the basis of prohibited consanguinity.



I need some decent lights for shooting video. I checked the B&H catalog, which has a wide range of video lights for studio work, but the prices for professional studio video lights start with a couple of zeros on the end and climb quickly into the stratosphere. So I made a quick trip to Lowe's, where I bought a couple of 500W quartz-halogen work lights for $15 each. If the light is too harsh, I'll just bounce them off a couple of large white cards.



This afternoon, I'm doing a phone interview with the Amateur Observers' Society of New York about Illustrated Guide to Astronomical Wonders. I've done lots of phone interviews with radio stations, but this will be the first I've done with an astronomy club. I'm looking forward to it.


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