Most people are well aware of the traditional materials offered to married couples to celebrate their wedding anniversary. You know the kinds of thing I mean – ruby for instance is the gem of choice for a 40th anniversary, although why a chunk of chromium infested aluminium oxide should have been chosen for this year in particular I don’t know. The noble elements silver and gold are 25th and 50th respectively, while the hardest allotrope of carbon, represents the 60th celebration (diamond, that is). If you want the complete list check out our traditional wedding anniversary gifts page, but if you want something a little different, a reference for Kevlar, zeolites, buckyballs, or PVC say, take a look at our chymical wedding round-up.
Author: David Bradley
Acid test research project
This probably is not a project you could do for your school science project, unless you are really, really keen. Chemists at Queen’s University Belfast have developed a molecular system that acts like an ion-selective electrode across a pH range of 9. Prasanna de Silva and his colleagues, who featured in a special issue of Intute Spotlight recently, explain that their device has the advantage of operating on the nanoscale and so could be incorporated into microelectromechanical systems, or so-called lab-on-a-chip devices. The team used a set of four sensor molecules in relay to act as the quantitative version of universal indicator paper. One sensor does the hard work of sensitively responding to pH across approximately 2 pH units and then hands on the baton to the next, which in turn works hard over the next 2 pH units and so on covering 9.5 units on the pH scale. de Silva says that the molecular devices show an almost linear intensity-pH profile that is reminiscent of the response of a conventional glass pH electrode but a thousand times smaller than even micrometer-scale intracellular pH electrodes.
“Our research shows a simple and predictive way of greatly extending the sensing range of molecular sensors,” de Silva told Sciencebase, “We do it by using a set of four sensors to act somewhat like a 4×100 m relay team. One sensor does the hard work of sensitively responding to pH across approximately 2 pH units and then hands over the task to the next one, which in turn works hard over the next 2 pH units (approximately) and then hands over the task to the next one etc. In this way we get a range of 9.5 pH units whereas the normal range of a molecular sensors is only 2 (as you learn in high school science).”
Scientists have thought about this problem before (resulting in the famous universal indicator), there was no quantitative version of a molecular universal indicator until now. The nearly linear intensity-pH profile is reminiscent of the glass pH electrode’s response, even though the electrode is obviously a lot bigger in size (the smallest ones are micrometer-sized and used for intracellular pH measurements), de Silva told me.
You can get the full experimental details in their JACS paper on this: Analog Parallel Processing of Molecular Sensory Information
Levitation for Real
This isn’t exactly your average high school science fair project, in fact please don’t try this for yourself without proper supervision, as you’ll need a magnet, a chunk of high temperature superconductor and a flask of liquid nitrogen, oh and a pot that won’t crack when you pour in the liquid nitrogen. (Standard cyro lab safety equipment is recommended) When this video first hit the streets, lots of people said it was a fake, but what it is, is a classic demonstration from modern physics of non-classical behaviour in materials cooled below a certain critical temperature. The effect in question is well-known to scientists working with superconductors and is known as the Meissner-Ochsenfeld effect, or more commonly the Meissner effect. Poor old Ochsenfeld rarely gets a name check. It was discovered by the pair in 1933, so it’s nothing new to physics, relatively speaking.
So, what’s going on? How does the high temperature superconductor levitate the magnet and if it’s high temperature why does it have to be cooled with liquid nitrogen to near 77 Kelvin, that’s almost minus 200 Celsius). Well, we’ll answer the last question first, it’s the easiest. The High is relative! Low temperature superconductors only work at close to absolute zero, minus 273 K, so anything at the almost balmy temperature of liquid nitrogen is positively smoking!
Now to the hard bit. Superconductors are unusual ceramic materials. They have lots of weird properties not least the fact that they superconduct, which means they can carry an electric current with zero resistance. So, picture the magnetic field around the magnet, if you bring the magnet close to the ceramic when it’s at room temperature, the magnetic field lines pass straight through. But, when the ceramic is chilled below its critical temperature to make it a superconductor, those magnetic field lines can no longer penetrate the ceramic. But, that doesn’t really answer the question, it just begs another – why can the magnetic field not penetrate the superconductor?
The final answer lies in the fact that the magnet induces tiny electrical currents in the superconductor as it is lowered towards the superconductor (remember, a moving magnetic field induces a current in a conductor, it’s the basis of the dynamo and electrical generation). However, this is no ordinary conductor, it’s a superconductor and so those electrical currents keep flowing round and round in infinite circles within the superconductor. Now, conversely to a moving magnetic field producing a current in a conductor, an electrical field will induce a magnetic field and because of Fleming’s right-hand rule, that induced magnetic field matches the pole to which the superconductor is exposed by the placing of the magnet in the first place.
The resulting repulsion is counteracted by the downward force of gravity and the magnet hovers neatly above the superconductor, at least until it warms to above its critical temperature.
Just for completeness, I should also point out that the magnet is effectively pinned in position by an effect known as flux pinning, which is caused by magnetic field lines getting snarled up by impurities in the superconductor. But, if you set the magnet spinning it will spin without friction (well not in this demo because there is air friction). Incidentally, this levitation effect has a serious application in some types of Mag-lev train.
A semantic chemist – fixed
I recently interviewed Robert Parker, the new Managing Director of RSC Publishing, you can read his interview in the February issue of chemistry news magazine Reactive Reports in which he discusses a new approach to the publication of scientific papers, RSC Prospect, and how it will benefit readers and the scientific community at large. It would be interesting to know what users think to the RSC’s new approach to meta data and a semantic chemical web.
“We needed a meaningful way of identifying compounds uniquely and one that’s machine readable – InChI fits the bill. Similarly, CML offers us a way of structuring lots of the science within a paper to both preserve the original science and do interesting things with it, and by demonstrating some of these applications, we hope to encourage wider adoption,” Parker told me, among other things. Check out the interview for his take on Web 2.0 for chemists, blogs and wikis, and more.
Also, featuring in Issue 62 of Reactive Reports:
Take the Volcanic Fast-track to Nanotube Production Igneous rock from the Mount Etna
volcanic eruptions could be used to mass produce carbon nanotubes, according to researchers in Germany.
Alumination at last! More powerful solid rocket fuel could be the product of research into a new
class of compounds containing aluminum and hydrogen compounds, according to an international research team.
How Wine Producers Might Save Asthma Sufferers from Sulfites Ozone could replace sulfites
as the preservative of choice in a new asthma-friendly approach to wine production.
Mass debate on stem cell research
Just £300,000 (about $600k) is being plugged into a national public debate by the UK government on stem cell research. According to Science and Innovation Minister Malcolm Wicks the UK’s two major public funders of stem cell research will use the cash to run a national public discussion about this cutting-edge area of science.
The Biotechnology and Biological Sciences Research Council (BBSRC) and the Medical Research Council (MRC) will receive the funding as part of the government’s ScienceWise initiative. The aim will be to find out what are the public’s concerns, views and attitudes to this face-most moving area of science. It will also provide a forum for revealing the challenges that researchers face and the potential benefits of stem cell science.
At today’s launch Wicks said: “The Government believes that stem cell research offers enormous potential to deliver new treatments for many devastating diseases where there is currently no effective cure. Huge numbers of people are affected by these diseases and Britain is a world-leader in stem cell research. But there must be a proper dialogue with the wider public on the future of stem cell research. We need to raise public awareness about the potential opportunities
and challenges in this area.”
One key element of the initiative is to raise awareness of the world-class stem cell
research being carried out in the UK, at centres such as Newcastle University, and the progress being made towards practical treatments.
BBSRC’s Julia Goodfellow added, “It is essential that scientists working in areas such as stem cell research engage in a real dialogue with the public. The new programme will give scientists, funders and the government up-to-date information on what the public really think about stem cell research while giving people the chance to voice their views and concerns.” So, basically repeating what Wicks said. The MRC’s chief Colin Blakemore, had a slightly different slant. “Scientists who work
on stem cells want to ensure they maintain the trust and support of the public for their research,” he said. “But to achieve this, we need to explain what work is being carried out and why it’s being done.”
So, is £300,000 enough to do the job? Compare this with the ludicrous amounts of money available to anti-science type lobby groups which amount to millions and it really does look like a pittance. Half of that amount could easily be eaten up by an independent designer putting together a corporate logo for the project and the other half will have gone on snacks and wine for the launch party buffet, or am I being far, far too cynical? You tell me.
New radiation warning sign
The sixtieth issue of the “new” Alchemist is now online over on Sciencebase partner site ChemWeb.com. As you might expect having reached this tender age, we’ve put on a little weight, as of this issue there will be more chemistry matters.
In this week’s issue, new symbolism in the world of ionizing radiation, a rubber band theory that requires no stretch of the imagination to work, and an atomic approach to murder. Also in this week’s issue, new catalysts could make use of wasted natural gas that is simply vented and flared at oil wells and archaeological evidence that Christopher Columbus’ fellow travelers struggled to find enough silver. Finally, crumpling hydrogels could give chemists a taste for plastic origami. Also in this issue our new awards/announcements section – this week fueling fuel cell research to the tune of $1.5million.
Check out the ChemWeb Alchemist every fortnight.
Chemistry aside though, what do Sciencebase readers think of the new radiation sign the IAEA wants to make standard? To me it looks far more cluttered and confusing than the original trefoil. the IAEA says that lots of people don’t know what the trefoil represents, but surely if you come across a huge lead box with a big red triangle on it and a symbol that looks like something out of a science fiction movie you’re not going to break it open to see what’s inside…or maybe some people would. The IAEA says there are too many needless deaths and serious injuries from accidental exposure to large radioactive sources and that tests have shown that the meaning of this new symbol for category 1, 2, and 3 radiation sources is far more obvious than the old trefoil. It will mean a whole new redesign for those movie sets though.
Shadowy face recognition
Face recognition is the most obvious approach to identification but it suffers from a major drawback – shadows and bad lighting. If there is inconsistent lighting in a room or on a face then it becomes difficult to produce reproducible digital image of the face for face recognition algorithms to work with. Now, researchers in China have turned to near infra-red to help computers cope with variable lighting conditions and so recognize even the most shadowy of faces.
Face recognition is a key function of the human brain…let me put it another way, from a very, very early age we can all recognize faces, from the familiar view from mother’s knee to spotting a friend in a crowd. Computers too can process a digital image and compare it with a database entry to carry out simple face recognition. But only if the light is right. Throw in a few shadows, sunlight through a window, or a flickering overhead fluorescent light, and the computer usually cannot spot the difference between John Doe and Joe Bloggs. Stan Li believes the answer lies in the near infra red, you can find out more tomorrow in the latest issue of spectroscopynow.com or get an advance view here.
Desktop Hockey Face-off
Scientists sure know how to have fun, Iain “Beaker” Larmour and Lauren “Comical Flasks” Rutherford of QUB, in Norther Ireland, square up for the match of the century playing micro mechanical hockey on a super water repellent, a superhydrophobic, material, that makes a duck’s back look positively damp.
There is a serious objective to this work. Superhydrophobic materials have been sought for many years. “Much of the recent research on hydrophobic materials has been inspired by the water-repellent nature of lotus leaves,” says team leader Steven Bell, “they show a double roughness on their surfaces (nanohairs on microbumps) along with a waxy coating. Very few materials have come anywhere near being this hydrophobic, or water hating though. Bell and his colleagues, Graham Saunders and Iain Larmour have now developed a remarkably straightforward method for treating metals which mimics the microstructure of lotus leaves. “The process simply involves dipping the object to be coated in a solution of silver or gold ions, this coats them with a double-roughness metal layer thinner than a human hair. Secondly the object is dipped in a solution which creates single layer of water-repelling fluorinated molecules similar to Teflon.” The resulting surfaces are so water repellent that they can be immersed in water for several days, but are completely dry when removed. Similarly, drops of water deposited on the surface form almost perfect spheres that roll off unless the surface is kept completely flat. “The surface tension in these water ‘balls’ is strong enough to hold them together during the hockey game in the video,” Bell told Sciencebase.
Sharp-eyed readers will probably be wondering about how they players scored. “The goal areas in the hockey field were treated to make them hydrophillic (water loving) so that drops that roll over them get temporarily trapped,” Bell told me.
The research is published in Angew Chem
Natural Family Planning
Could the contraceptive pill be replaced by a “natural” approach to family planning? It could if a study by Petra Frank-Herrmann of the Department of Gynaecological Endocrinology at the University of Heidelberg, Germany, proves reproducible (pardon the pun).
She and her colleagues have demonstrated that using two indicators for the fertile period in a woman’s menstrual cycle and avoiding unprotected sex during that time is just as effective as the contraceptive pill for avoiding unplanned pregnancies. The study was published in Human Reproduction this week.
The symptothermal method (STM) uses temperature and cervical secretion to pinpoint a woman’s fertile time. The German team carried out the largest prospective study of the method yet and found that if couples abstained from unprotected sex during this time the rate of unplanned pregnancies per year was 0.4% and 0.6% respectively. Out of all the 900 women who took part in the study, including those who had unprotected sex during their fertile period, 1.8 per 100 became unintentionally pregnant.
“For a contraceptive method to be rated as highly efficient as the hormonal pill, there should be less than one pregnancy per 100 women per year when the method is used correctly,” Frank-Herrman explains, “The pregnancy rate for women who used the STM method correctly in our study was 0.4%, which can be interpreted as one pregnancy occurring per 250 women per year.”
The authors were also surprised by the relatively low rate of unintended pregnancies (7.5%) among women who had unprotected sex during their fertile period. ‘If people are trying for pregnancy you expect a pregnancy rate of 28% per cycle,’ said Frank-Herrmann. ‘Therefore, we think that some of the couples were practicing conscious, intelligent risk-taking, and were having no unprotected sex during the few highly fertile days, but had unprotected intercourse on the days at the margins of the fertile time when the risk of pregnancy was lower.’
Medical marijuana
“The US Food & Drug Administration’s (FDA) position on medical cannabis is incorrect, dishonest and a flagrant violation of laws requiring the government to base policy on sound science,” claims Joe Elford, Chief Counsel for patient advocacy group. The organisation, the largest of its type in the US promoting safe and legal access to cannabis for therapeutic use and research, has filed a lawsuit demanding that the federal government “cease issuing misinformation on medical cannabis and correct the information it has released.”
There is growing evidence that the active ingredient in cannabis (THC, or tetrahydrocannabinol) can alleviate the often debilitating pain suffered by those afflicted with multiple sclerosis (MS) and HIV/AIDS. However, given the drug’s illicit status in most countries many governments have not acceded to its free use as a therapeutic agent nor encouraged systematic research and clinical trials to demonstrate efficacy or otherwise. Moreover, the ASA suggests that the US government is stifling valid research and spreading disinformation about the benefits.
The pharmacological action of THC results from the compound binding to the so-called cannabinoid receptor CB1, in the brain. The presence of this specialized receptor suggests that there are natural THC-like (cannabinoid) compounds made or used in the body. THC has been repeatedly demonstrated to have analgesic effects but the “high” associated with its use have precluded it from mainstream medical research. Several research teams are, however, investigating variations on the THC theme that retain the analgesic properties but do not produce a high. Such a product would be more acceptable to the pharmaceutical industry and the regulatory authorities, but requires a lot of work with the native compound to help scientists work out what chemical factor leads to the high and which part produces just the analgesic effect.
Fellow blogger “Joe” discusses many of the issues in more detail. He points out that since the 1980s the FDA has actually approved Marinol, a synthetic THC analogue for pain in cancer. But, the conflicting response of successive Bush adminstrations (viz the first Bush administration, in the early 1990s cancelled a compassionate use program and in the late 1990s, the Office of National Drug Control Policy threatened action against physicians who recommend or prescribe marijuana. California doctors and patients subsequently sued the federal government.
Opponents of medical marijuana use cite apocryphal evidence that it is a gateway drug to harder substances. However, one must consider the plight of terminally ill patients who seek relief from intolerable pain and suffering. Ironically, many terminally ill patients do indeed end up using much harder drugs in the end. Diamorphine? Heroin by another name.