Month: August 2006

Periodic Post

Periodic table of sex

Mosts chemists get to see some wacky periodic tables during their careers – circular ones, spiral ones, ones that rearrange all the elements etc etc. Then there are the foody ones and then there are the giant periodic tables, the arty farty ones, the online version, the flash table.

And, then there’s the periodic table of sex.

I didn’t think it was real at first, but several sciencebase visitors have been searching for this incredible object during the last few days, so I thought I’d uncover the truth. Apparently, just such a PT exists, its elementary in the most lewd way, but is available from Amazon. Apparently, allposters.com have stopped selling it, so I’d grab one while you can: Periodic table of sex

It’s not every post I get to categorise as chemistry, sex and geek all at the same time, but this one was simply begging for it. I hate to think what good-ole Dmitri Mendeleev would have made of it though, but surely it’d make the perfect gift for the chemistry student in your life. Wouldn’t it?

Natural power for TV

A posting about telemarketing on digg reminded me how a teacher friend used to mess with the heads of cold callers, asking them obviously dumb questions.

One of the less subtle was to ask the telemarketer from British Gas, which now also offer electricity as well as natural gas to UK customers, whether he’d be able to run his TV from the gas supply.

They caller would politely tell him no, but become increasingly frustrated as my friend continued his line of enquiry embellishing his questions all the while with thermodynamic gobbledegook and nonsense about improved efficiency. He could keep them hanging on for hours…

Of course, the irony is that once we all have methane-fed fuel cells in our homes, we will indeed be running our TVs off natural gas!

Glucosamine hydrochloride

The UK’s Food Standards Agency announced (August 21, 2006) that it has received an application from a food additive manufacturer to use glucosamine hydrochloride in a range of foods, including smoothies and sports drinks. The company, Cargill, makes glucosamine hydrochloride from the black mould Aspergillus niger.

But, why would they want to do this? Cargill wants to use its glucosamine as an ingredient in a range of pasteurised food products. These will include fruit juices and fruit juice products, such as tomato, tomato mixtures and fruit; smoothies, dehydrated instant drink mixes, fermented milk-based products, such as yoghurts and fromage frais, sports drinks and iced tea drinks.

Glucosamine has an almost mythical status among sufferers of various types of joint pain as a product that can supposedly ease their suffering. It gets this reputation from the fact that it is a naturally occurring amino-sugar that acts as a major building block of complex proteins called glycosaminoglycans, which form part of the structure of cartilage. As such, people with arthritis and other disorders that affect the joints hope that ingesting large quantities of this compound will somehow help their bodies to self-repair. This chain of causality has not been demonstrated.

Indeed, a recent study published in Nature Clinical Practice Rheumatology (2006, 2, 356-357) reported that:

“The publication of the results from the GAIT (Glucosamine/Chondroitin Arthritis Intervention Trial) represents a milestone for evidence-based therapeutics in OA. This large, NIH-funded, multicenter trial showed that neither chondroitin, glucosamine, nor the combination, was more efficacious than placebo for the treatment of pain in OA. The absence of efficacy was demonstrated both for the primary outcome, and for nine preselected secondary outcomes. The positive control, the COX2 inhibitor celecoxib, showed efficacy compared with placebo.”

Cargill’s glucosamine is produced through chitin sourced from Aspergillus niger, whereas all other known commercial glucosamine products are derived from shellfish, so there really won’t be any difference between their additive and the glucosamine present in a whole range of products at this time.

But, the myth of glucosamine is just that, or so it that large-scale study would suggest. A conventional diet will usually provide all the necessary precursors for this compound, so unless you’re malnourished and you’d then be experiencing other symptoms too, it is unlikely that adding glucosamine to your diet will ease your joint problems.

If the FSA sees fit to approve glucosamine hydrochloride from A. niger, UK consumers can expect to see a whole new rash of drinks with this additive purporting to help the aged and those with joint and related problems. They will not be able to make any serious medical claims about the product, but will almost certainly be able to ramp up the price nevertheless.

My advice? Stick to that healthy diet and drink plenty of tap water (if you don’t like the taste fill a jug and leave uncovered in the fridge for an hour or two before drinking to allow volatile chlorine compounds to escape.

Sunscreen and skin damage

When I first wrote about the doubts scientists were raising concerning sunscreens in Chem & Industry magazine some time in the early 1990s, it seemed that the findings would simply confuse consumers and cause a storm among manufacturers. Unfortunately, that doesn’t seem to be the case, sun worshippers carried on frying themselves, slapping on only meagre amounts of purportedly protective cream, partly out of laziness and partly because it is just so expensive and manufacturers continued to sell their products by the bucket load. Then research emerged that showed lack of sun exposure not only risks rickets but could increase the chances of you getting internal cancers, as opposed to the much feared skin cancer. As if consumers were not confused enough.

Now, US researchers have shown that applying too little suncream can actually turn the UV-absorbing chemicals against you.

When skin is exposed to sunlight, ultraviolet radiation (UV) is absorbed by skin molecules that then can generate harmful compounds, called reactive oxygen species or ROS, which are highly reactive molecules that can cause “oxidative damage.” For example, ROS can react with cellular components like cell walls, lipid membranes, mitochondria and DNA, leading to skin damage and increasing the visible signs of aging. The link with skin cancer itself is actually not so clear cut as some lobbyists claim.

However, when sunscreen is applied to the skin the UV filters in the sunscreen, reduce the amount of UV radiation penetrating the skin. Over time, though, the filters themselves are absorbed by the skin leaving the surface vulnerable to UV once more. The UV filters (octylmethoxycinnamate, benzophenone-3 and octocrylene) widely used in sunscreens themselves generate reactive oxygen species (ROS) in skin when exposed to ultraviolet radiation, augmenting the ROS that is naturally produced. [These new results are similar to those on which I reported in C&I ten years ago, DB]

Kerry Hanson of the University of California Riverside and colleagues now report that these three UV filters only work well if sunscreen is reapplied frequently to prevent ultraviolet radiation from reaching these filters. Without reapplication, these compounds could be just as harmful as not using sunscreen at all.

The team will publish their findings in a forthcoming issue of Free Radical Biology & Medicine.

“Sunscreens do an excellent job protecting against sunburn when used correctly,” said Hanson, who works in the laboratory of Christopher Bardeen, an assistant professor of chemistry at UCR. “This means using a sunscreen with a high sun protection factor and applying it uniformly on the skin. Our data show, however, that if coverage at the skin surface is low, the UV filters in sunscreens that have penetrated into the epidermis can potentially do more harm than good. More advanced sunscreens that ensure that the UV-filters stay on the skin surface are needed; such filters would reduce the level of UV-induced ROS. Another solution may be to mix the UV-filters with antioxidants since antioxidants have been shown to reduce UV-induced ROS levels in the skin.”

“For now, the best advice is to use sunscreens and re-apply them often — the Skin Cancer Foundation recommends every two hours, and especially after sweating or swimming, which can wash away sunscreen — to reduce the amount of UV radiation from getting through to filters that have penetrated the skin,” Bardeen said. “This, in turn, would reduce ROS generation.”

But, having read this please also read my write-up on how to sunbathe safely

Pluto dwarved

Well, the votes were counted and the decision made: Pluto was demoted to less than planetary status. The astronomy and science textbook publishers are rubbing their hands with glee as new editions will have to be printed and plucked from their shelves by eager homeschoolers and teachers keen to get their facts right.

Unfortunately, things are never so clear cut.

A fierce backlash has begun against the decision has begun, says the BBC. The lead scientist on NASA’s robotic mission to Pluto, Alan Stern, called the ruling “embarrassing”, while the chair of the committee, Owen Gingerich, implied that the vote had been “hijacked”.

http://news.bbc.co.uk/1/hi/sci/tech/5283956.stm

It seems, however, that many of those arguing against the demotion of Pluto to dwarf planet status had already left the meeting because of other commitments before the final voting took place. Indeed, only 10% of the 2700 delegates at this meeting actually voted!

Gingerich, was among the 90% who couldn’t vote as he had to return to the US. He says electronic balloting must be introduced in the future. Stern too was unable to vote, “I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room – you can’t even claim consensus,” he told the Beeb.

This left the anti-Plutonists with an open field to throw this tragic rock into a lower orbit.

Stern expressed even further consternation but added that he could not see the resolution standing for very long and wasn’t planning on editing the manuscript for his forthcoming astronomy textbook just yet.

Caltech’s Mike Brown, co-discoverer of UB313 is quite happy to live in a solar system with just eight planets thought. “Eight is enough,” he told the Associated Press, jokingly adding: “I may go down in history as the guy who killed Pluto.”

Whichever way the solar count finally goes, it seems that the arguments are adding a frisson to astronomy that has been sadly lacking for many years. Even if the textbooks stay the same, bookshops would be well advised to stock up early for the Christmas rush as a whole new wave of budding astronomers clamber for space books and maps of the night skies.

European Chemistry Congress

The very first European Chemistry Congress starts Sunday and runs till the end of the month. The event is being held in Budapest, Hungary, at Loránd Eötvös University, and promises to be an astounding affair showcasing chemical sciences in Europe and bringing together chemical and molecular scientists from industry, academia and government institutions across Europe and from around the world.

The conference has been organised by EuCheMS (European Association for Chemical and Molecular Sciences, formerly FECS) and is co-sponsored by GDCh, RSC and SFC with an old friend of mine, Professor Jean-Marie Lehn heading up the scientific committee.

It’s a long time since I wrote about the rise of European chemistry in a feature article for Science magazine (Science 18 June 1993 260: 1738-1739), and it seems that this conference has been a long time coming. But, like they say, better late than never.

ChemWeb Alchemist

In this week’s Alchemist news round up: oscillating carbon fibres could usurp silicon in the world of microscopic video, find out how a sugar molecule seen only on anthrax spores could help defeat the bacterium in the event of a bioterrorism attack. We also report on how the US government has asserted that levels of dioxins and related compounds have fallen in meat and poultry and we discover how to make see-through silver.

Finally, a new surfactant allows oil and water to be mixed and unmixed on demand and could mitigate oil spill disasters. Here’s the skinny: Canadian chemists have synthesised a new surfactant that allows oil and water to be mixed and de-mixed on demand depending on whether carbon dioxide or air is bubbled through the mixture.

Read more…

Science fair projects and experiments

With a new school year almost upon us, there is a pressing need for parents everywhere to get advance warning of the kind of science conundrums (conundra?) they will face when their little darlings return with that first batch of science homework.

As ever, sciencebase is here to help with a bench covered in science fair projects, a labful of science experiments and all the science books for home study you can bear.

A word of warning, please DO NOT try to light your last barbecue of the summer with liquid oxygen…

UB313 Xena

UB313

Astronomers working under the proverbial umbrella of the International Astronomical Union (IAU), have come up with a new definition of “planets” and smaller “solar system bodies” such as comets and asteroids, this week, but the definition is not without controversy.

If the definition is approved by the astronomers who are pointing their telescopes at each other at the IAU General Assembly in Prague, this week, then our Solar System will have 12 not nine planets, with more to come.

Our heavenly neighbours will be the eight classical planets that dominate the system, including Pluto, whose status hung in the balance for a while. But, there will be an additional three planets in the new burgeoning category of “plutons” described as Pluto-like objects — and Ceres. Pluto will at the time of writing remain a planet but be the prototype for the new category of “plutons.” Anything smaller than Pluto but with similar properties, presumably, will become a pluton rather than a planet.

With the advent of powerful new telescopes on the ground and in space, planetary astronomy has gone though an exciting development over the past decade. For thousands of years very little was known about the planets other than they were objects that moved in the sky with respect to the background of fixed stars. In fact the word “planet” comes from the Greek word for “wanderer”. But today hosts of newly discovered large objects in the outer regions of our Solar System present a challenge to our historically based definition of a “planet”.

The new definition accommodates the eight bodies from Mercury to Neptune and Pluto because they orbit a star and aare in “hydrostatic equilibrium,” which basically means they’re “almost round.”

Not everyone is happy with the new definition. Caltech’s Mike Brown co-discoverer of UB313 (aka Xena) is appalled by the notion that there could be many more than the “special” nine planets orbiting our sun. Estimates put the figure at 53 round objects are already known.

He told the Globe and Mail, that ‘To me, the word ‘planet’ always meant something special. Nine was special. Maybe 10. Fifty-three? No,…in some ways it drains the excitement of what I thought was an exciting find. Turns out it was the 12th planet. Who knew?’

Moreover, a counter definition that knocks Pluto off the list altogether is being mooted by rebel astronomers at the same meeting, according to New Scientist. This version tacks on the idea that to be a planet the object must be the dominant heavenly body in its orbital region. Unfortunately for Pluto, Neptune (not to mention Uranus) is much bigger and their orbits cross…so Pluto would, according to The Register, be planet-ish but not quite planetary.

Final voting will take place Thursday.

But, never mind the astronomers’ concerns, what are astrologers making of all this? Surely, their charts will all have to be redrawn if Xena is in the ascendent and Pluto on the decline! Maybe in the Age of Aquarius we shouldn’t be worrying about such trivia as planetary definitions and get back to solving other more pressing matters here on earth.

Generate molecular formula

Generate molecular formula

A rather common search on the sciencebase site seems to ask how to generate a molecular formula. Well, the method I use is to go straight to ChemSketch and fire up ACD/Dictionary, type in the name of the compound I want to produce and paste it into the ChemSketch window. That gives you the everyday 2D structure. A quick click of the “3D Viewer” button does what it promises to do and opens the molecule as a 3D view. At this point, it’s still flat and has to be optimised, so the “3D optimization” button is next. That renders the molecule as a three-dimensional molecular structure. Now, save as a mol file and as a ChemSketch structure.

Now, I follow one of several paths at this point depending on what use I am to put the molecular formula. If it’s to illustrate a scientific piece I’d often be simply using the 2D version. But, if I want something a bit flashier I’ll usually use the 3D view and tweak the settings to change background colour, add or remove hydrogen atoms, or re-render it as a space-filling or ball and stick molecule, depending on which format will best get across the chemical message.

Alternatively, I may shut ChemSketch altogether and re-open the mol file in Diamond from Crystal Impact, which can produce wonderful pseudo photographic quality molecular structures. And, if these aren’t good enough, the next step is to do a full 3D rendering in Pov-Ray, which provides scenic backgrounds, quasi-shadowing, and other wonderful effects to produce a beautifully metallic textured molecule hovering in space, for instance.