Nano News is Good News

Gray goo nanobots

The research of Arpad Putzai about a decade ago in which he fed genetically modified potatoes to rats and purportedly observed deleterious effects, kicked off the whole anti-GM movement in the UK. In a recent Guardian interview with Pusztai, his current position on the subject is probably best summed up by an early quote from the interview:

“We’re eating things that we haven’t eaten before, and I challenge anyone to be able to predict what will be the consequences of this, particularly the consequences for our immune system.”

One might argue that today we are consuming thousands of things that were not available to ancestors from bananas and kiwi fruits to chocolate truffles and skinny café latte mochachino with marshmallows and sprinkles. Excess and overindulgence aside, our bodies seem to cope immunologically with a huge range of foodstuffs that are newly available in terms of the evolution of our enzymes.

Indeed, it was Bruce Ames, of Ames test for cancer causing fame, who pointed out that every day the DNA in every cell of our bodies is exposed to thousands of putatively harmful agents and those or mainly from the natural products of the natural environment. So, why should a few GM potatoes engineered to ward off insect larvae without the use of pesticides be any different?

While we may not be adapted to the specifics of GM crops our bodies do seem able to cope with novel foods. Moreover, we are still evolving (just look at the enzymes we have that cope with cow’s milk and alcoholic drinks that apparently occurred only once we became an agricultural species 10,000 years ago. The same argument might be applied to the advent of nanoscience. However, are the lessons science should have learned from the public relations debacle sparked by Pusztai’s revelations ahead of peer review being ignored again as the nanotechnology age dawns?

Nanoparticles and nanocomposites are essentially any substances that exist as collections of individual entities in the size range of 1 to 100 nanometres in diameter. So at least an order of a magnitude bigger than atoms and molecules. The biggest molecules, proteins, some supramolecular structures and the fullerenes all fall below this range, although they almost overlap with the smallest of genuine nanoparticles. Conversely, nothing bigger than a hundred nanometres, a couple of hundred at a push, can be described as nanoscopic, rather at the micrometre scale you are looking (with a microscope) at microscopic particles. So the fullerenes are not nanoparticles and neither are the kind of microscopic particles of asbestos that are known to cause serious health problems. Nanoparticles are in between these two extremes.

Nanotechnology is, of course, an entirely different simmering pan of aquatic chordates than GMOs. Although saying that we have co-existed with organisms that are genetically modified throughout evolution as well as particles that just happen to be in the size range 1 to 100 nm.

Nevertheless a whole field of nanotoxicology has emerged over the last three or four years and a forthcoming special issue of the International Journal of Nanotechnology (IJNT, 2008, vol 5(1), pp 1-160) will cover many of the issues as well as reporting on various recent studies into the safety or otherwise of nano materials. Among the themes are investigations into the putative effects of nanoparticles on the human lung, blood serum, and epithelial cells, as well as reports covering how to design safety into nanotechnology, and developing a risk management framework. There is certainly a need to monitor the emergence of nano, in terms of occupational, environmental and consumer risks.

Whereas Pusztai’s results published a decade ago triggered a public relations catastrophe from which UK genetic scientists have yet to recover, it doesn’t seem that nanoscience and nanotechnology are going down quite the same road in terms of media scare stories and public anxieties.

As with GM there is huge potential in this burgeoning field of discovery. “Nanomaterials offer tremendous societal benefit,” says cell biologist Thomas Weber of Pacific Northwestern Laboratory, guest Editor of the special issue of IJNT “from improving medicines to everyday items such as automobiles and aircraft or your favourite fishing rod.”

Unfortunately, the tabloids have latched on to the concept of a “grey goo” produced by myriad self-replicating nanobots of which K Eric Drexler warned in his nano-pioneering 1986 book The Engines of Creation, but that is probably an impossibility. Such nanobots are themselves likely to be many decades away and will because of the laws of supply and demand be all-but self limited. It is interesting that the cosmetics industry learned the public relations lesson very quickly, however, quickly discarding the nano label from products that contain liposomes, for instance, before consumers began worrying about their face turning to grey goo.

PNL’s Weber is well aware of the potential for a public relations crisis when it comes to nanoscience. “There are diverse types of nanomaterials being produced with unknown toxic potential,” he says, “This combination requires responsible stewardship by the scientific community over this rapidly developing field to enable maximum benefits while minimizing negative outcomes.”

“Advances are being made on various fundamental scientific aspects of the toxicity of nanomaterials as well as on rapid-screening tools to assess toxicity,” explains SK Sundaram, also at PNL, and a guest Editor on the IJNT special issue, “These advancements will help in enhancing the public awareness and dispelling many myths in this field, we hope.”

Despite the imaginary notion of a ubiquitous grey goo, the relative lack of tabloid media interest may be due in part to the diverse and esoteric nature of nanoscience. Whereas anyone might imagine some kind of monster GM tomato, it is rather difficult to visualise the scale of nanoparticles and of what they are composed, let alone how such particles might behave.

Quesnoin from Tropical Paris

A newly discovered diterpene quesnoin with a novel ring structure, bridged by a single oxygen atom, has been isolated from 55 million-year-old amber from the Eocene geological period by Akino Jossang and colleagues at the National Museum of Natural History in Paris.

According to a report in Chemistry World, Jossang said that, “It is very difficult to isolate pure known compounds in amber, so to discover a new structure was unexpected and exceptional.” The biosynthesis is intriguing but whether or not the quesnoin has any potential applications is a different matter.

The compound is related to one from a tree found today only in the Amazon rainforest adding to the weight of evidence that Paris was once a tropical region. Anyone who has spent an August there will know how that might have been.

Spinneret host Tony Williams tells me that he used the new ChemSpider manual deposition scheme to add this new compound to the database. “We are about to rollout the ability for anyone to deposit structures on ChemSpider. This one took me 5 mins…about 3.5 of that drawing the structure!” The entry description includes the DOI of the original paper and links directly to it.

Nature’s Missing Crystal – Found It!

K4 crystal

Diamond is not unique! Nature’s missing crystal discovered! A crystal as beautiful as diamond! Those were the themes running through dozens of articles in the media about a discovery made by Japanese mathematician Toshi Sunada of Meiji University. The original press release proclaimed that he had discovered a theoretical crystal structure with the same symmetry properties as diamond but with handedness, or chirality, and that this knocked the crown from diamond’s uniqueness.

Unfortunately, he soon discovered just how embarrassing press attention can be as chemists and crystallographers began filling his email inbox with messages alerting him to the existence of the exact same structure he was “predicting” already having been found. I asked Sunada about what happened.

“After my article appeared [in Notices of the American Mathematical Society; PDF file] a few people pointed out the oversight,” he told me, “They were rather sympathetic to that the difference of culture between mathematics and other sciences that leads to such ignorance.” He adds that although he hadn’t been aware of the known crystal structure until his modelling constructed it before his eyes, the people who contacted him were unaware of the history of his work in this area stretching back a decade. The original work that led to the discovery of the structure was done by AF Wells in the mid-1970s.

It highlights just how far apart different fields in mathematics and the sciences are despite efforts by various agencies and funding bodies to attempt to build multidisciplinary bridges. The debacle reminded me of how it took a mathematician colleague to point out to Harry Kroto and his colleagues that the structure of the all-carbon molecule buckminsterfullerene and the symmetry laid bare by their spectra was suggestive of a truncated icosahedron, a soccerball, in other words!

It makes me wonder what other discoveries have we missed because the sciences are no longer as joined up as they were in the heyday of the nineteenth century polymaths like Faraday. Put another way how much money is wasted re-inventing the wheel. Without wishing to criticise Sunada or the referees of the original paper, but if a chemical colleague happened to have seen his structural simulations they might have spotted th fatal flaw in the argument that much sooner. Perhaps the Scandinavian idea of hot-desking should be introduced into labs, hot-benching you might call it, to boost the potentially innovative cross fertilisation of ideas. Or, how about a cross-disciplinary approach to peer review, send to two experts and an additional referee in another field entirely if the paper claims true novelty.

Anyway, back to Sunada’s work. It may at first seem that here was merely a mathematician modelling something that chemists and materials scientists already knew, but although one half of his discovery was not a discovery at all because the structure was already known, one aspect of his work could save chemists a lot of searching in vain. “My result pins down that there are only two crystals having these properties,” he told me.

You can read more about Sunada’s discovery in my SpectroscopyNOW column this week.

PubMed Central Submission Now Mandatory

The US’s National Institutes of Health (NIH) has a Public Access Policy that is set to become mandatory following President Bush’s approval on Dec 26th 2007. This change will mean that NIH-funded researchers will be obliged to submit an electronic version of any of their final, peer-reviewed manuscripts to PubMed Central, as soon as the paper has been accepted for publication in a journal.

Many researchers are pleased with the move and Peter Suber outlines the implications in detail in the January issue of the SPARC Open Access Newsletter. Citing the cons are several of the non-OA publishers who claim that NIH has no rights over the intellectual property of the science it funds and that research papers should remain the copyright of the publishers. They argue that the value added by the publication process will effectively be handed over to PubMed Central by the submission process without compensation. Others argue that the publishers have had it too good for many years.

There remain several outstanding issues which will no doubt be argued over in the months to come.

Attractive Health Measures or Magnetic Manure

Magnetic manure

We probably all know at least one person who swears by their magnetic charm bracelet for preventing travel sickness, reducing arthritic pain or even helping them through situations that induce an attack of social anxiety disorder. These bracelets and other devices (some are in the form of headbands, others pendants, blankets, knee braces, shoe inserts, there’s even one you wear in your pants to improve your sex life) use magnets of a similar strength to those that make shopping lists stick to your refrigerator or let your kids spell out rude words without you realising…

…in other words, they’re not very strong and so probably have absolutely no physiological effect whatsoever. So, this $5billion industry founded in ancient Greek mythology is almost on a par with homeopathy for having no real scientific basis. Or is it?

Serious research, being carried out in a serious university laboratory, with serious financial backing recently hit the headlines with proclamations that a short application of a magnetic field to an inflamed joint could somehow improve blood flow and reduce swelling. Thomas Skalak, chairman of biomedical engineering at the University of Virginia and his colleagues lead the field in the area of microcirculation research, the study of blood flow through the body’s tiniest blood vessels. This status presumably helped them secure $875,000 of US taxpayers’ money from the National Institutes of Health’s National Center for Complementary and Alternative Medicine.

Initially, they set out to examine a claim made by the companies that sell “therapeutic” magnets: that these devices somehow increase blood flow. Skalak’s team used magnets of 70 milliTesla (mT) field strength, which is about ten times stronger than a common refrigerator magnet, but still very weak, the magnetic field of an MRI machine, for instance, is up to about 3000 milliTesla (3 T in other words). The researchers measured blood vessel diameter before and after placing the magnets up against lab rats.

They found that the magnets seemingly had a significant effect on blood vessels. Those that had been dilated became narrower and those that were previously constricted widened. Apparently, this implies that the magnetic field could induce vessel relaxation in tissues with constrained blood supply, ultimately increasing blood flow; how the magnet knows which way to stimulate the effect is not known. In a more recent study, the team treated the hind paws of anaesthetized rats with inflammatory agents to simulate tissue injury. Therapeutic magnets were then applied to the swollen paws immediately. The researchers say they say significant reduction in swelling (oedema), although there was no effect if there was any delay between injury and application.

According to Skalak, “The FDA regulates specific claims of medical efficacy, but in general static magnetic fields are viewed as safe.” So, could magnets be used to improve blood flow following muscle injury, say, as many of the headlines surrounding this press release claimed?

Well, what I’d first like to know, is did the researchers use a double-blind control? Did they, for instance, apply non-magnetic objects of equal size, shape and weight and at the same temperature to a second set of inflamed rat hind paws to examine whether those had any effect on blood vessel dilation? Did they have a set of inflamed rats that were not treated at all? How did those groups respond? The research paper on which the press release is based was published online in November 2007 in the American Journal of Physiology and Heart Circulatory Physiology.

Given that one of the major tenets of sports injury treatment is ice and compression could it be that the very act of pressing an object against the inflamed joint simply acted as a compressive heatsink, reducing local temperature of the inflamed region and at the same time temporarily reducing blood flow during the compression?

It’s just a thought, but couldn’t any metallic object of a reasonable size, 10-20 mm would be adequate for a rat paw, act as a cold compress, asks my good friend Stephan Logan. Logan supplies scientific educational equipment, including neodymium rare earth magnets, and points out that these have a field strength of several thousand milliTesla (1.3 T is typical for the standard neo magnet N42) and so has a keen interest in scientific claims made about much weaker magnets, such as those used in the experiments, knowing that a nasty pinch when flesh is trapped between two neo magnets is one of the well-known physiological effects but has nothing to do with mystical field effects

The Virginia press release, and consequently much of the media, claim that since muscle bruising and joint sprains are the most common injuries worldwide, Skalak’s discovery has “significant implications”. He rightly points out that, “If an injury doesn’t swell, it will heal faster – and the person will experience less pain and better mobility.” The extrapolation of the magnetic research to the notion that “magnets could be used in much the same way ice packs and compression are now used for everyday sprains, bumps, and bruises, but with more beneficial results, is not necessarily supported.

Magnets could be used, but where is the evidence that they reduce swelling any more than a conventional cold compress? Indeed, does injecting a rat’s foot with an inflammatory chemical simulate adequately a sprain or strain? The release says, “The ready availability and low cost of this treatment could produce huge gains in worker productivity and quality of life.” That’s a big extrapolation from a small laboratory study to the whole of sports injury medicine. Anyway, if commercialised are these therapeutic magnet ever likely to be as cheap and readily available as a bag of frozen peas? I doubt it.

Nano Pico Femto Satellites

Swarms of satellites each weighing less than 100 grams and not much bigger than a personal digital assistant or even a cell phone could soon be heading for space. These so-called femto satellites could quickly displace the behemoths of yesteryear that weigh in at up to a tonne and may revolutionize applications in telecommunications, military, entertainment, science, weather and climate forecasting, at much lower fabrication and launch costs.

We’ve all seen TV footage of those enormous rockets thrusting upwards from distant launchpads, seemingly hanging in the air and yet accelerating upwards at incredible speed in order to pierce the sky and enter orbit.

Onboard such a rocket, will usually be a payload, a satellite, destined for earthly orbit, a device that until recently may have weighed more than a tonne. These enormous satellites cost a fortune to build, even more to launch, and still more to cover the insurance premiums. Smaller satellites would be so much better for dozens of reasons and over the last decade, their size has dropped below the one tonne mark, and then to the few hundred kilograms, more recently to micro satellites that weigh a few tens of kilograms.

However, there was never any reason not to build something smaller that could be reduced in size, and so we have seen in recent years the launch of a flotilla of “nano” satellites that weigh between 1 and 10 kg, then pico satellites that are just a few hundred grams, and soon we could see femto satellites that weigh less than 100 grams. [NB the nano, pico and femto referred to here are arbitrary descriptors of the relative mass of the satellites. For more on the true meaning of nano, pico, and femto]

Warren Leary, writing in the New York Times ago, described the promise of microelectromechanical systems (MEMS) as applied to satellite technology and hinted at the possibility of a satellite-on-a-chip. He discussed the work of Siegfried Janson and colleagues at The Aerospace Corporation, in El Segundo, California, and quoted him as describing, ‘Fully integrated satellites that could be mass produced cheaply by the hundreds and sent into space in groups to perform a variety of tasks.”

We are not quite at the stage of sending out satellite swarms but the miniaturisation of satellites has continued apace with designs, such as the CubeSat system, allowing researchers and companies to design satellites based on a standard payload that

“Pico-satellites are viable development platforms for testing new technologies in the space environment, explain M.W.R. Alger and K.D. Kumar Department of Aerospace Engineering, at Ryerson University, Toronto, Canada. Writing in the International Journal of Manufacturing Research (2008, 3, 48-79), “The opportunities given to fly the earliest pico-satellites as secondary payloads have benefited all facets of the space community both by effectively training the next generation of spacecraft designers and by pushing the boundaries of space technology at largely reduced risk and cost.”

They point out that these pico satellites have a lot to contend with, “Space is a very unforgiving environment, with many different hazards then those found on the Earth. The major hazards to overcome are: radiation, temperature variations, space debris, and out-gassing.”

The first pico satellites, weighing less than a kilogram, flew on the OPAL and Sapphire missions and subsequently their success led to the CubeSat standard, with devices about 100x100x100mm. “The strategy for deploying these satellites in orbit involves launching a group of small pico-satellites in a deployment device known as a Poly Pico-satellite Orbital Deployer (PPOD),” the researchers explain, “The PPOD integrates with the launch vehicle and carries three normal sized CubeSats.” Several of the most successful CubeSats have been built by students at various universities. Now, many other teams around the globe have been building their own CubeSats.

“Femto-satellites [click the graphic for a better view] will be the next new class of satellites,” the researchers say, “There is a possibility of shrinking the capabilities of a typical pico-satellite bus (attitude control, imaging missions, communications etc.) on to a single chip.” It is possible that current consumer manufacturing processes for personal digital assistants and cell phones will drive the development of femto satellites. Scientists have already developed a prototype configuration – a Ryerson Femto Formation Flying Experiment (RyF3ex) spacecraft as a demonstrator technology. This femto satellite will simply report back its altitude to a ground station.

Femto satellites will have several limitations, however, and are more likely to be launched as a swarm by a larger spacecraft. “Femto-satellites derived from this technology maybe an interesting approach for deep space exploration where a larger satellite could launch a cluster of disposable femto-satellites to examine a planet or asteroid of interest and after completing this mission, the larger satellite could orbit another planet and deploy a new cluster to do a similar mission,” the researchers add.

Sharp-eyed readers will recall I mentioned this impending item in an article on the Earth’s escape velocity entitled 40320, Such a Significant Figure, just so you know I do occasionally pull the threads together.

Chemical Sensitivity

This week’s Spinneret post actually points you to my latest Alchemist column on ChemWeb.com but also goes into a little more detail on one of the items reported there regarding pesticide contamination.

First off, Environmental research gets a boost from NIH in the form of a $6.8million grant to establish three DISCOVER centers to study the effects of environmental pollutants. Crystallography reveals the cellular machinations of the humble hydrogen peroxide molecule in The Alchemist this week, while fatty samples suggest that all of us harbor at least one pesticide or other persistent organic compound in our tissues. In environmental news, researchers have turned to gold to help them convert biomass into a useful chemical feedstock, while in theoretical studies it still matters, relatively, that electrons and nuclei are massively and speedily different. Finally, crystals behaving badly in supramolecular chemistry could herald new approaches to technological problems.

Read current issue of The Alchemist here.

Anyway, back to the contentious item on global contamination, which referred to news that almost everyone in Spain, and putatively the world, may be contaminated with at least one pesticide. I did have some misgivings about reporting on this and my concerns were brought into sharp relief by an Alchemist reader friend who happens to be a retired organic chemist with a great deal of experience.

He points out that the item on finding persistent organics in blood serum should really be put into perspective. “The fact that many of these studies find mainly halogenated compounds may well simply reflect the exquisite sensitivity of the detectors used in capillary gas chromatography to halogen,” he says, “these devices will pick up nanomolar concentrations of compounds containing chlorine or bromine.” He also asks whether strict controls were used by the investigators in this research and points out that work in this area submitted for regulatory filing requires stringent controls beyond simply showing a peak that has roughly the same Rf as a suspected pollutant.

More to the point, however, he questions the significance of finding traces of DDT or even DDE in serum. “If this were truly perilous the landscape should be littered with victims,” he says.

40320, Such a Significant Figure

40320, Such a Significant Figure

I am currently writing a post about pico and femto satellites for Sciencebase, these devices are tiny compared to the enormous one tonne behemoths many of us would picture if asked to visualise an artificial satellite (more on that later). Anyway, the earth’s escape velocity at sea level from a standing start was a figure I needed to hand while writing the piece.

I found a value in metres per second, converted to kmh and did a quick search with Google Toolbar just to get some references and to confirm my calculation. The kmh value, as you may have guessed, comes out at about 40320. However, Google’s auto-suggest offered me a search for the phrase “40320 plain bob major”, which was odd, to say the least, but would have been the obvious figure to a bell-ringing friend of mine. He would have immediately spotted it as an astoundingly long peal of bells. In fact, this very long peal was rung in 1963 in Loughborough, England, using eight tower bells in all possible permutations 8 multiplied by 8 factoria (8×8!) would come to 322,560 blows. Apparently, it took more than 18 hours to ring the changes all the way through.

Of course, the peal of 40320 arises because of the 8 factorial connection, 8×7×6×5×4×3×2×1 (8!) and has nothing to do with earth’s escape velocity, but it hooked me on a bit of guided searching looking for other significant mentions of the number 40320.

40320 is the number of minutes in 4 weeks and so February with its usual 28 days, should be designated “International Factorial Appreciation Month” according to one author (except in leap years, such as 2008, of course).

Kentucky 40320 is a spot on Ford Hampton Road in Kentucky, USA.

Item 40320 in the SigmaAldrich catalog of chemicals is 2,2-dimethylglutaric acid and bug number 40320 in Ubuntu Linux – “devhelp starts with an “empty” page area, which is not redrawn”, whatever than means, apologies to Ubuntu fans, I’ve not been there, nor done that yet.

The PubMed ID (PMID) 40320 points to a paper in the August 1979 issue of the journal Tijdschr Diergeneeskd entitled “Relationship between the presence of meconium in newborn lambs and postnatal pH and blood gas tension levels” and Tinyurl page 40320 displays a scan of a cheque for $950 with the filename bloodmoney.jpg.

Assuming Rudolph is at the front, there are 40320 ways to arrange the other eight reindeer (this simply relies on the 8! value mentioned earlier and could apply to clusters of any eight objects). It ignores “Olive the other reindeer”, you know the one who used to “laugh and call him names”. At the time of writing there were 207 cars listed for sale according to Google that had 40320 miles on the clock and just 5 with that same number in kilometres, while according to Cancerwise, 40320 women will be diagnosed with uterine cancer this year.

40320 is the item number for a “please shower” sign at BackyardGardener.com and BIOS 40320 is the Aquatic Conservation course covering global freshwaters, science and policy at University of Notre Dame.

Most of these various facts are totally unrelated, except those invoked by 8! Amazing what you learn writing about femto satellites. If you have any other fascinating examples of the number 40320 please give them a mention in the comments box below.

Chemical Irritation

Not so much a chemical information post today as a diatribe against natural terminology used by the countless chemophobes out there.

I had a query this morning from a reader asking whether adding bleach to the water used with their cut, fresh flowers would reduce fungal infections and so somehow prolong their bloom time. I suspect there’s probably a drop of truth in the idea, but in trying to find a definitive answer I found a gardening type page that discussed the issue.

In it, the author of the item, Marion Owen (whom I am sure is a lovely person) asserts that, “If you don’t like to use chemicals to prolong the life of your cut flowers, there are “natural” alternatives.” She then goes on to list various chemicals that one might add – a penny, aspirin, lemon-lime soda, bleach, lemon juice, sugar, bleach, and listerine. At this point, I’m not worried about whether my blooms stay blooming lovely or not, but am taken aback by how she seems to be defining the word chemical. She’s not alone, of course, millions of people make similar assertions about detox diets that avoid chemicals (so, what do you eat when you’re on a detox diet, raw energy?)

Anything Marion and her readers might add to a vase of flowers is made from chemicals. The flowers themselves are made from chemicals (proteins, carbohydrates, fats, water, minerals etc), lemon juice (water, citric acid etc). Even the water itself (dihydrogen monoxide)!

But, more to the point it’s that use of the word “natural” with which I take umbrage, natural usually preserved for non-synthetic chemicals (although there is no actual distinction in nature between natural and synthetic, humans are “natural” after all). Maybe she meant to specific agrichemicals or chemicals produced by the industry for the specific purpose of reducing mould and extending bloom life. Wouldn’t you rather use something designed specifically for the job rather than adding a random selection of household chemicals to the vase. What, if the bleach and that carbonated lemon-lime drink react, catalysed by the copper penny, to produce some noxious vapour? At best, the flowers would more likely fade faster, but you might also get a nasty whiff of something when you lean over to catch their scent!

Anyway, how can adding aspirin be considered a natural alternative to adding chemicals? Of course, you might use sap from the cricket bat willow (Salix alba) which contains salicylic acid, the active metabolite of aspirin, but that would still be adding chemicals to the flowers, natural or not, and the very process of extracting the sap, is that natural?

Of course, the whole activity of cultivating blooms, hacking them from their plant and sticking them in a vase and leaving them to die with no chance of producing offspring is in itself not an entirely natural thing to do. But, how do you segregate anything humans do from the natural world in the first place? Human intellect and activities are as much a part of the natural world as the very flowers we admire, the insects that would normally pollinate them, the moulds and microbes that grow on them and apparently shorten the blooming lives, the insects and fungi that will rot them on our compost heaps, and the soil bacteria that will feed on them producing the right conditions for next year’s flowers.

Plasticine, Salt, and Melting Snow

Salt water ice freezing

Why do they grit the roads with rock salt in winter? What does the salt do to the water to reduce ice on the roads? Is this somehow related to how salt affects the boiling point of water? Keywords to search for: colligative properties, boiling, freezing, ions, solutions, solvent, Raoult’s law

Meanwhile, I’ll let Plasticine models from Ithaca and cheesy music explain:

Incidentally, if it is too cold, no amount of salt will prevent the roads freezing, but if climate predictions are to be believed then that will not be a problem for much longer. (Unless the computer models are all wrong and we are heading for another ice age…now where did I put that hot-water bottle?)