David Bradley – Page 283

Dental plans

Maybe I shouldn’t tell you this online, and my son will be more than a little miffed, if he reads this, but he recently had a trip to the orthodontist and is now the proud owner of an upper teeth realignment device, a brace, as we used to know them in the good, old days. So why am I telling you this?

Well, the fitting of the brace raises an interesting question of mechanics as to what the brace is actually doing. It is composed if small metal plates effectively fixed along a piece of tough wire. The plates are seated on the front of the teeth, with one plate on each tooth and the wire is anchored somewhere in the back of the mouth. Now, what I cannot understand is why. The upper incisors of the orthodontic patient in question seem to slope inwards, rather than jutting out. My gut feeling is that pushing the teeth backwards with little metal plates is going to make them more recessive if anything. So, how does this system work? What are the true forces involved in dental realignment and how does pushing the teeth in the direction they are already going make them move into the correct position.

Maybe all will become clear with the next visit…meanwhile, I have to thank the NHS for funding this work, without it, it would be costing us a small fortune…

UPDATE: Treatment went well and he now has lovely straight teeth, as does our daughter who followed the same path a few years later.

Culmination of Fulmination

Mercury fulminate

German chemists recently determined the crystal structure of a compound the alchemists knew as “Knallquecksilber”, but which goes by the formal name of mercury(II) fulminate. The compound is highly explosive, sensitive to heat and shock and its control in the form of a detonator material for dynamite gave Alfred Nobel his big break.

The new crystal structure corrects some previous mentions in the scientific literature, by revealing it to be an almost linear molecule. But, never mind the chemistry you can read more about that in the September issue of my Intute Spotlight. It is that name that intrigues me. Knallquecksilber.

Quite literally it means “bang quicksilver”, quicksilver being silvery mercury’s liquid alchemical name. Bang quicksilver hardly slips off the tongue, so a better translation might be exposive quicksilver, which isn’t quite so crisp and subtle as the German word, but close.

I had a chat with a German chemist friend about the etymology of this name and the lack of a subtle literal translation from the German into English. It’s common to quite a few German words, zeitgeist, meaning literally time-ghost or spirit of the times, being another favourite. My friend pointed out that knallen (verb) describes something exploding with a big bang, a
Knall, the crack of a whip or the banging of a door might be described using knallen in German, for instance.

But, he also pointed out that the English name for this salt itself – mercury fulminate – harbours an explosive origin. Fulmination, of course, being another word for a violent explosion and so perfectly apt for describing big bang quicksilver.

Periodic Table Names

Periodic table names, it’s an odd phrase, what does it mean? It obviously means something to dozens and dozens of visitors to ChemSpy.com who hit the site from the search engines looking for that exact phrase. I puzzled for ages trying to figure out what these visitors were after. Were they simply looking for different types of periodic table? There are lots of sites out there that discuss traditional, modified, circular, three-dimensional and some rather bizarre periodic tables (there are PTs for desserts and sexual positions, (NSFW) you may care to know).

Then I spotted a follow up search from a cluster of subsequent visitors, they were searching for not just “periodic table names” but “periodic table with names”. Then a query came in that was even more explicit – “periodic table with element names”. Duh! I thought to myself. They’re simply looking for a PT that not only has the elemental symbols but gives the full name of the element to which the symbol refers. Well, the answer to that query is easy – yes. Best among a big bunch has to be good friend Mark Winter’s site based out of Sheffield University WebElements.

So, there’s the answer. Unless you know otherwise…

More Periodic tables:

PT rings and more, PT of visualisation methods

There is Iron in Them There Bills

Have you ever wondered what it would be like to make a dollar bill smoothie? Well popular science guru Steve Spangler certainly did and with the help of a super powerful neodymium magnet he demonstrates in the video below just how much iron you would get if you were stupid enough to drink the smoothie. The iron is present in certain magnetic inks used to print a fistful of dollars.

There’s iron in them there bills…you might say!

Dollar bill video

So, now you’ve watched the video, you’re probably wondering, what are neodymium, or rare earth magnets and why is it so much stronger than a standard fridge magnet? Well, unlike conventional ferric or iron magnets, neodymium magnets are composed of iron, boron, and as the name would suggest, neodymium. The general chemical formula for this alloy is Nd₂Fe₁₄B which basically means for every 14 iron atoms in the material there are two neodymium atoms and one boron atom. That special blend (pardon the pun), however, means they can be up to about twenty times stronger than conventional ceramic magnets. Check out the HowStuffWorks site for a simplistic explanation of magnetism.

I asked magnetic expert (soon to be) Dr James Stephenson, who has probably forgotten more about magnets than I ever knew, why it is that the neodymium, or neo, magnets are so much stronger. The strength of a permanent magnet is down to how strong are the individual magnetic moments of the atoms from which it is composed and that’s down to how many electrons can be aligned in each atom, he explains.

Put simply, “Rare-earth magnets, also known as nib magnets, are stronger because the individual atomic magnetic moments are stronger and that adds up to a stronger magnetic field overall,” he says. Taken individually, an isolated atom of a rare earth element, such as neodymium, has gaps in its so-called d [electron] f-shell. When Nd is alloyed with boron and iron those gaps get filled up to a maximum of 14 electrons in the f-shell of each Nd atom, this results in a very strong dipole. “In other words,” Stephenson adds, “more electrons means more current and as a result the magnetic field due to each dipole is higher.” So, there you have it.

By the way, it’s not illegal to blend a dollar bill unless you plan on trying to spend it later, but to be on the safe side bring a friend along, not only can you make sure it’s their dollar bill you blend, but you can claim it was their idea when the FBI turn up at the door too!

Male-Female Crabs Split their Difference

Male-Female Crab

David Johnson and Robert Watson thought they had seen all there was to see in the Chesapeake Bay in almost three decades until they pulled out a crab from the way that had a male left half and a female right half. Now, that crab, acquired by Romuald Lipcius of the Virginia Institute of Marine Science at the College of William & Mary, has moved sideways into the world of natural metabolites where its gynandromorphic peculiarities have helped scientists, for the first time, discover that some molecules can be made only by one sex and not the other.

The male-female crab is a unique example of the blue crabs. It turns out that the males of this species produce a natural metabolite that is absent in females. This suggests that some complex biochemistry is underway that is activated only in males. Robert Kleps of the University of Illinois at Chicago and colleagues have isolated this small molecule and identified it as 2-aminoethylphosphonic acid (AEP), an uncommon but well-documented natural metabolite.

We used low-field NMR using phosphorus-31, to observe the small molecule, explains Kleps. He points out that science tends to get lost in the rush for higher field NMR running hydrogen-1 and carbon-13 on 100 kilodalton proteins. However, he adds that, “Even low-field NMR spectroscopists can make interesting discoveries. I’m very happy to have stumbled over this metabolite, while doing basic research on invertebrate metabolism.”

So, why might the existence of a metabolite in the males of this blue crab species and not the females have any bearing on our everyday lives? Well, there are well known differences between the sexes in people, such as disease susceptibility, anatomy and drug metabolism. Kleps points out that these differences might in fact be due to the presence or absence of a crucial metabolite.

Now that the existence of a sex-specific metabolite has been found for one animal the search is on for others, including ones that might exist in people.

For more details on the NMR study check out my column on SpectroscopyNOW.com, the research paper itself is available in Plos One.

You can hear a description of the crab from Lipcius here and listen to Kleps’ podcast

Hubble Beater, Bottom Up and Explosives

Nebula Lucky

The latest edition of Intute Spotlight is now online. In it I discuss a 300 year old chemical conundrum completed, a ground-based Hubble beater, and IBM’s plans to move from the micro world to the nano, although it won’t mean smaller premises.

Explosive Crystal [Sep 2007 – chemistry,materials]

Three centuries after its discovery by alchemists, the crystal structure of mercury fulminate – an explosive detonation …

Hubble Beater [Sep 2007 – astronomy]

Cambridge and Caltech astronomers have devised a new digital sensor for their telescopes that effectively cancels out the “twinkling” caused by the Earth’s atmosphere and allows them …

Bottom up to nanotech [Sep 2007 – materials,physics]

Two back-to-back papers published by IBM scientists could herald the long-awaited advent of molecular or nanotech computing devices. …

ChemModLab Enters ChemSpider Web

A new project that combines work from two distinct cheminformatics groups will form a new system for the delivery of modeling and identification of commercially available compounds for biological testing.

The North Carolina State University Exploratory Center for Cheminformatics Research group, developed ChemModLab to compute quantitative structure-activity relationship (QSAR) models and this will be pulled together with the almost 18million structures currently in the ChemSpider database. These structures are sourced from the scientific literature, chemistry database providers and commercial chemical vendors and screening library providers.

“This data collection provides an ideal basis for combing the QSAR capabilities of ChemModLab with the compound collection and indexing of ChemSpider to allow identification of virtual hit compounds via in silico screening, says ChemSpider boss Antony Williams.

Office depot

Some of us are old enough to recall a time when forward-thinking TV shows like the BBC’s classic Tomorrow’s World promised us the “paperless” office. This was during a period of massive technological development when mainframe computers were coming to the fore and the very first personal computer was being hinted at. It seems that the paperless office never happened. By the time I’d left University and started work in a publishers there was more paper than ever, almost every document was either faxed, duplicated or printed out using the new-fangled laserjet printers that nudged out the dot-matrix machines just as I arrived…

Even today, with everyone existing in a virtual second world and doing far more online than ever before offices are still piled high with email printouts and memos, and downloaded computer software manuals that simply must be printed for easy reading by the less technophilic members of staff. Maybe there will come a time when we have a chip embedded in a temple at birth and it links us up directly with all those invaluable Web 4.0 services we’ll be using by then…but you can bet your life there will still be someone demanding a printout. I hate to think where they’ll stick the ink cartridges.

Droning On About Bee Chemistry

Not spiders, but bees. Researchers at the University of Illinois Urbana-Champaign have identified an odorant receptor that allows male bee drones to find a queen in flight. The receptor is present on the male antennae and can detect an available queen up to 60 metres away, which is quite a feat in chemical detection. This is the first time an odorant receptor has been linked to a specific pheromone in honey bees.

The “queen substance”, a pheromone, was first identified decades ago, but scientists have only recently begun to understand its structure and its role in hive life. The pheromone is a primary source of the queen’s authority. It is made up of eight components, one of which, 9-oxo-2-decenoic acid (9-ODA), attracts the drones during mating flights. It also draws workers to the queen and retards their reproductive growth.

MMR and Statistical Manipulation

Measles virus

When I was still at high school, way back in the late 1970s, there was a health scare that got a lot of media attention. Apparently, there was a perceived risk that the whooping cough vaccine could cause brain damage. The fall off in vaccination for this disease is claimed to have led to the widespread outbreaks of whooping cough in 1979 and 1982, there having previously been almost zero annual cases. At the peak there were some 60,000 cases.

Fast forward to the near present and you will recall similar scare stories about the combined measles-mumps-rubella vaccine, the MMR, and claims by researcher Andrew Wakefield (Lancet, 1998) that MMR could cause autism in some children. It’s a topic guest blogger Michael Marshall covered on Sciencebase in November 2004. It seemed that, at the time, the debate was pretty much over. However, despite repeated demonstrations of the apparent inadequacies of the original research into a link between MMR and autism, the issue is resurrected on a regular basis. Most recently in a cover story in The Observer, which drew much flack, but also left the chattering classes once more in a flap.

Right now, I’m looking at an article from the print edition of The Times offering an answer to the Question of the Week – “Measles or vaccine?” – the article talks of how measles has reappeared and it is apparently all down to many parents’ reluctance to have their children vaccinated with the MMR jab. The article talks of “herd immunity” and how enough children have had a double dose of MMR which should stave off an epidemic. The emergence of herd immunity, of course, will be little comfort for a parent whose child experience any of the potentially severe side-effects of vaccination.

In the article, pictured alongside a blow-up of the measles virus and an image of a nasty-looking hypodermic needle, are two charts, one showing the number of cases of measles in the UK from 1940 to the present day and the other showing the number of deaths over the same period. Incidence of the disease ebbed and flowed during the period up to the early 1970s whereupon cases began to fall rapidly from a peak of 800,000 a year in the early 1960s to just one or two hundred a year by the mid-1970s.

The MMR vaccine was introduced in the US in 1971 and later in the UK, thereafter incidence of measles has pretty much fallen to levels close to zero. It seems that the pre-vaccine drop had another cause, presumably reduced overcrowding, improved nutrition, better hygiene and healthcare. No one knows at what point this fall would have reached a plateau.

In contrast, the second chart of death rates shows an exponential decline in measles deaths since the 1940s, by about 1970 measles deaths were also close to zero. The risk of getting measles is about one in three, assuming no vaccination coverage at all. The risk of serious consequences to this disease, which personally I had in 1972 or thereabouts, is somewhere between 1 in 5000 and 1 in 15,000. Compare that to the risk of death in a road accident. According to Transport2000 , the UK’s national environmental transport body, each of us has a 1 in 17 chance of being killed or seriously injured in a road crash during our lives. Such figures damn the disease statistics somewhat. Of course, vaccination does come with some risks, but adverse reactions, such as seizures with an associated risk of brain damage, exist at the 1 in 10,000 level.

There has been one UK death from measles since 1992 (as opposed to the several hundred each year during the 1940s). The unfortunate victim was apparently suffering an underlying lung disease for which he required long-term immunosuppressant drugs. He was very unfortunate to be exposed to the measles virus, and when he contracted the disease he was very unlikely to have recovered. This is one fatal case. Even with near 100% vaccination, there would still be a finite risk of any random member of the population contracting the disease. Unfortunate, but true. The statistics would not lie surely?