Author: David Bradley

Alchemists, crucibles and chemistry

AlchemistWhat alchemist’s den would be complete without a crucible? The tough little vessels used for mixing all those odd ingredients, goat urine, cow’s blood, sweat, philosopher’s wool, saltpeter etc etc…

Now, the 500-year old mystery of how crucibles could survive all that chemical punishment and high temperatures has been revealed by archaeologists at University College London and Cardiff University.

Earlier research had demonstrated that the crucibles are found in archaeological sites across the world, including Scandinavia, Central Europe, Spain, Portugal, the UK, and even colonial America. Many researchers have tried to reproduce these vessels but have always failed.

Now, writing in Nature, the researchers reveal using petrographic, chemical and X-ray diffraction analysis that Hessian crucible makers made use of an advanced material only properly identified and named in the 20th century.

Marcos Martinón-Torres explains, “Our analysis of 50 Hessian and non-Hessian crucibles revealed that the secret component in their manufacture is an aluminium silicate known as mullite (Al6Si2O13). Today mullite (not to be confused with mullet) is used in a wide range of modern conventional and advanced ceramics, such as building materials, electronic packaging devices, optical materials and catalytic converters, as well as in ceramic matrix composites such as thermal protection systems and liners for aircraft and stationary gas turbine engines.

Mullite was only described in the 20th century although the makers of crucibles were exploiting its properties almost half a millennium ago. It was produced by firing a crucible made from kaolinitic clay to above 1100 degrees.

Mullite is extremely resistant to heat, chemical and mechanical stresses, making it perfect for the Alchemist’s den. It is thanks to the availability of Hessian crucibles that the discoveries of several chemical elements and their thermochemical behaviour took place.

‘Crucible makers were not aware of mullite, but they mastered a very successful recipe, and that’s why they kept it constant, and secret, for centuries.’

Technological whirlwind

Best of Technology WritingFancy a whirlwind tour of some of the best technology writing of the year? As part of the digitalculturebooks series from the University of Michigan Press, Brendan Koerner has compiled some of the most stimulating and fascinating feature articles from the web and print media by the likes of the NYT’s David Bernstein, New Republic’s David Bell, Mike Daisy on Slate, Dan Ferber in Popular Science magazine, and many more.

The subjects covered are incredibly diverse, covering search engines, wikis and online social networking to the quest for a personal jet pack and the invention of the karaoke machine (which has apparently made it’s inventor not one Yen).

This neat little tome offers a grand over view (as well as a whirlwind tour!) of most technological niches you care to mention and highlights just how amazing human tool-making has become. Even for the tech-savvy reader it springs quite a few surprises.

Koerner is a contributing editor for Wired (which means he writes for the magazine and has his name on the masthead, I presume), a columnist for the NYT and Slate.

In the world of technology the pace is fast and the stakes are high. Jump into that whirlwind and prepare to be inspired.

Best of Technology Writing 2006 is available from Amazon.com, of course.

What is Thallium

Thallium poisoningA former colonel in the FSB (the successor to the KGB) has allegedly fallen foul of chemistry. Alexander Litvinenko, 43, a vocal critic of Russian President Vladimir Putin, fell ill on November 1, after a meeting in a London sushi bar, reports the BBC.

Litvinenko is on life support in University College Hospital having allegedly been poisoned with a potentially lethal dose of the heavy metal thallium polonium. His condition is apparently serious but stable and he is under 24-hour armed surveillance. The BBC claims that his condition could be the work of the Russian Secret Service. Thallium (nor polonium) is certainly not available “over-the-counter” to the general public.

The alleged assassination attempt is revealed just as the British secret services try to exploit the marketing of the new James Bond movie – Casino Royale, starring Daniel Craig in the role of 007 – to recruit new spies. One British agent told BBC Radio 1 listeners that the secret services always work within the law and there is no license to kill. This thallium polonium attack comes in the wake of the gunning down in Moscow of journalist Anna Politkovskaya in October 2006 and perhaps does suggest that someone, somewhere does have a license to kill.

But, what exactly is thallium and why is it poisonous?

Thallium, Tl, is the element with atomic number 81 and lies just below indium in the periodic table (same column as boron, aluminium, and gallium). It’s tasteless, colourless, and odourless and would be undetectable if sprinkled into food or a drink in a restaurant.

Thallium ions have the same charge and are approximately the same size as potassium ions. As such, they can reach most tissues including the tissues of the central nervous system (CNS). Like other heavy metals, it binds to sulfydryl groups in the body disturbing numerous biochemical processes.

If you’re an ex-spy worried about meeting former colleagues in London sushi bars, you might be well advised to carry some D-penicillamine and Prussian blue with you. This combination can act as an effective antidote to thallium poisoning because these compounds have a greater affinity for the metal than the sulfhydryl compounds in your blood.

Lock up the cat for safer drugs

stereoselective catalystCanadian and Korean chemists have locked in a form of handedness into a common catalytic molecule that could make it useful for separating the building blocks of proteins, amino acids, into their chiral forms for biotech applications and drug development. The new locked up cat, might also be used to make purer and safer chemical starting materials for reactions in the drug, agrochemicals, and polymer industries.

Jik Chin and colleagues at the University of Toronto, Canada, working with Jong-In Hong’s team at Seoul National University, Korea to synthesise a cobalt(III) complex of the ligand "salen". Salen is a commonly used ligand in organometallic chemistry. It is a Schiff base formed from a two to one reaction of derivatives of salicylaldehyde and ethylene diamine. Complexes of this ligand are very effective catalysts for a wide range of reactions including epoxidation of alkenes.

Read on…

Statistics and low GI foods

New, healthier alternatives to processed food starches with a lower GI, or glycaemic index, may soon be on the menu, thanks to scientists in China and the US. The researcher have begun to unlock the secrets of starches that make dehusked grains, potatoes, and processed foods such as biscuits and breakfast cereals less healthy compared with low GI foods. Their statistical analysis of starchy data could lead to new processed carbohydrates that do not cause the worrying blood sugar spikes associated with conventional processed starch.

Now, Hamaker and his colleagues have looked at the various physical properties of rapidly digested starches (RDS) and SDS (slowly) to try and determine the underlying differences. They have found that the degree of crystallinity of the starch content is key. Semicrystalline structure is critical to the beneficial slow digestion properties of low GI foods but cook, or otherwise process, an SDS, however, and this semicrystallinity can be lost and a once-slow starch becomes an RDS.

Read the full story in my latest news round-up on SpectroscopyNOW.com

Heart disease and the death zone

atheromaArterial plaques represent a "death zone" within the artery in which white blood cells that would otherwise clear away such fatty deposits are killed before they can do their job.

The result is that these plaques eventually reduce the blood supply to the heart causing heart problems. These plaques can break apart at any stage in a person’s life, although most commonly in middle age, whether they are otherwise fit or not.

Chinese researchers have now used analytical chemistry to determine the toxic components of arterial plaques that are so deadly to white blood cells. Their finding not only improves our understanding of this form of heart disease, but might one day lead to new approaches to treating atherosclerosis.

Find out more in the latest news from SpectroscopyNOW.com

Frothy fakers

This week in the Alchemist, I report on how platinum metal is getting all in a frothy, man… Discover that the Europeans are faking it down on the farm, and find out how regulating a man’s estrogen levels might be used to reverse prostate disease and cancer.

Also in this week’s round-up we discover how to split a beam of light for the first time albeit ever so slightly using extract of lemon juice and find that squeezing metals into your balls (buckyballs, that is) could lead to improved solar panels and new, improved MRI medical scanning.

Read all about the latest chemistry news in my Alchemist column on ChemWeb

Eradicating polio

Researchers hope to revise the vaccine strategy for inocculating people in certain parts of the world against the crippling disease polio. Their approach could eradicate this endemic disease once and for all, they report, in this week’s Science magazine.

The new study, by researchers from Imperial College London and
international collaborators explains why the disease continues to afflict people in northern India. Poor sanitation and overcrowded living
conditions in Uttar Pradesh and Bihar pose a dual challenge to the
eradication effort because they encourage poliovirus to spread via infected faeces contaminating drinking water, they explain. This coupled with other infections and diarrhoea interfere with the efficacy of the
oral polio vaccine.

The researchers argue that the simple measure of using a ‘monovalent’
form of the polio vaccine alongside the standard ‘trivalent’ form in
these areas could sufficiently increase the effectiveness of vaccination
programmes to wipe out the poliovirus where it persists.

The trivalent vaccine currently in use contains weakened strains of all
three types of poliovirus, unlike monovalent vaccines, which are
strain-specific. The trivalent vaccine is typically used when more than
one strain of the poliovirus is at large in the population. The problem
with trivalent vaccines is that the three strains can interfere with
each other inside the body, producing immunity to one strain but not
another.

The researchers argue that as the type 1 strain of the virus is now the
dominant one in India, it would be more effective to focus on the
monovalent form of the vaccine.

Lead author Nick Grassly says, “The global polio eradication programme has achieved a great deal. As expected, the last remaining pockets of transmission are the biggest challenge. These pockets of transmission act as sources for all the outbreaks we see around the world today. Our research shows that in northern India the efficacy of the trivalent vaccine is compromised.”

Unaccepted Medline

Last week, I discussed how to get free research papers online without having to hack into any publisher’s database.

Now, my Google Alert for Journal of Biological Chemistry has raised an interesting issue on the MEDLIB-L list from Thomas B. Craig, Assistant Director of Library Services at The University of Texas Health Center at Tyler.

Craig points out that he gets a lot of eprint requests from users after JBC papers that simply don’t show up in his library system as yet being available.

As Sciencebase readers know, JBC puts its “Papers in Press” free online. There can be a few dozen of over a thousand available at its website at any one time. The journal indexing system Medline, automatically indexes these “in press” papers and so as Craig explained some time ago on MEDLIB-L, “we get Docline requests for them when a library does not recognize a citation as coming from JBC Papers in Press.”

The requests contain an ID number but no page or issue number, just an annotation to say: “e-pub ahead of print”.

The JBC papers are essentially preprints, they go live on the site even before they’re edited or accepted officially for publication.

Craig thus asked: “Does this type of paper belong in MEDLINE, and what is its usefulness when it has yet to be accepted and is subject to change?”

Early awareness of research in a particular area would be one reason, but this issue makes a mockery of the out-dated and pointless system of artificial media embargoes that journals such as JACS, Nature, PNAS, Science, and others slap on their papers to help them coordinate the press response to a particular paper’s publication. Moreover, given that a paper published ahead of acceptance and seen by more peers might lead to flaws being spotted that were missed by the official referees, before it goes to press, might help the review process and prevent dubious papers ever making it to the Table of Contents.

The recent suspected research fraud being investigated at the University of Missouri is just the most recent example in a string of problems associated with fabricated and massaged data stretching back decades.

Don’t judge a lemur by its cover

If you’re ever out lemur spotting, and thing you’ve seen an entirely new species, you may wish to refer back to US research published today in the journal BMC Evolutionary Biology wherein you will find a study that claims that different coat colour does not necessarily correspond to a different species for nocturnal lemurs. In fact, as with cats and dogs, coat colour does not mean an awful lot when trying to distinguish new species. Genetically speaking whatever the fur, it’s the genes that matter.

Kellie Heckman of Yale University and colleagues sequenced the mitochondrial gene for cytochrome b in seventy mouse lemurs. Originally, these lemurs were thought to belong to up to three different species because they live in different forest habitats and have distinctive coat colouration.

However, Heckman’s phylogenetic analysis came to the rather surprising result that all seventy specimens are actually identical genetically, to all intents and purposes; making them all Microcebus griseorufus.

While, the press release on this says the results are surprising, it then goes on to explain that these nocturnal animals use auditory cues and smell to recognise each other rather than judging who’s who on the basis of the coat they’re wearing. So, it’s not really surprising at all, when you think about it like that. After all, an extra wing stripe can separate to otherwise identical bird species, but birds are generally diurnal and have great day sight. Colours are pretty much a secondary thing at night no matter how good your eyes.

Meanwhile, the authors of the study offer a cautionary word for those searching for new species. They say that looks aren’t everything and that size, shape, geography, ecological, and most importantly genetic differences have to be taken into account to provide an accurate picture of species diversity.