David Bradley – Page 324

Bacteria build nano catalysts

Bacteria could be the key to improving metal catalysts for the chemical industry, according to research in Germany. Scientists from the Forschungszentrum Rossendorf in Dresden have exploited the survival skills of bacteria that live in uranium mining waste to make tiny clusters of the precious metal palladium. These tiny bullets, just a few billionths of a millimetre across, are much better catalysts than normal palladium, which is used in speeding up chemical reactions and in the catalytic converters of cars.

The bacterium, Bacillus sphaericus JG-A12 has a protective protein layer that allows it to survive in the extreme environment of a uranium mining waste pile. This protein layer comprises a grid of nanoscopic pockets of identical size that can trap toxic metal ions and prevent them from harming the bacterium by converting them into tiny clumps of insoluble metal.

Full story…

Scanning vegetative patients

Last week, Cambridge and Belgian researchers reported that they could observe almost identical brain activity in healthy volunteers as a patient purportedly in the persistent vegetative state following emergence from a coma (the patient was originally in a car crash in July 2005). The implications of this functional MRI work are that some (but by no means all) PVS patients may have consciousness to some degree despite their outwardly appearing inanimate.

It is incredibly tragic to imagine that there might be PVS patients who do have some consciousness but cannot move or communicate with the outside world. Functional MRI may in the long-term lead to a way to communicate with such patients.

That said, there is a long way to go before fMRI or any other technique can provide us with a full understanding of the persistent vegetative state and some researchers are cautious of extrapolating the Cambridge findings too far. Indeed, if you read my report about the research in the latest issue of SpectroscopyNOW.com, you can see quite clearly that the fMRI scan of the control volunteer and the patient are superficially similar – activity is in the same region, after all – but the level of activity appears to be markedly less prominent in the patient. This could have important implications for what is meant by such a patient having consciousness as we know it.

Much more research is now needed to help us redefine the PVS. This is perhaps a matter of some urgency given the current definition of PVS states that these patients cannot experience pain and suffering as these are attributes of consciousness.

Chemistry Central Journal launched

A new open access outlet for chemists’ peer reviewed research was launched today. Chemistry Central Journal. Publisher BMC says, the journal is the first international open access journal covering all of chemistry and will publish its first issue early in 2007.

Bryan Vickery, speaking today at the journal’s launch being held during the ACS meeting, said, ‘I am delighted by the number of noted chemists and scientists who have agreed to join the Editorial Advisory Board of the journal from the outset.” Among them is 1996 Nobel laureate Robert Curl. “I think open access journals are a great idea and am delighted to join this venture as a member of the Editorial Advisory Board,” he said.

Vickery continues, “Open communication of research results in physics and biomedicine has evolved rapidly over the last few years. Many believe Chemistry has lagged behind, with access to chemistry-related journals and databases still predominantly limited to subscribers only.”

Vickery explains that Chemistry Central Journal will offer a home for research in areas where there has previously been no open access journal available. “Chemistry Central Journal aims to change all that, by offering an open access publishing option to scientists worldwide,” Vickery says, “The journal will cover all areas of chemistry, and will be broken down into sections.”

Blue LEDs are too bright

Blue light-emitting diodes (LEDs) are really bright. Too bright for theorists to handle, in fact. Why? Because, the materials from which they are made usually have impurities that should make their glow much duller. Now, an international team of researchers has discovered why this is the case.

Commercially viable blue LEDs are based on the wide band gap semiconductor gallium nitride and indium gallium nitride and were invented by Shuji Nakamura then at the Nichia Corporation in 1993. By the late 1990s, they were widely available and now sit in an important technological niche in the development of large full-colour displays, LEDs for highly energy-efficient solid-state lighting to replace incandescent bulbs, and 400 nanometre laser diodes for optical data storage in high definition DVDs. However, the commonly used indium gallium nitride can only be manufactured at relatively low quality with high levels of impurities. Theoretically at least these impurities should quench the light the device produces, but it does not.

Full story out now, under the Intute Spotlight

Sex and phthalates

pvc dildos and phthalates It seems even the sex industry is not immune to chemophobia, according to a recent Greenpeace Netherlands announcement, users of PVC sex toys destined for orificial use should not. Use them, that is.

According to Greenpeace, these plastic devices can contain “extremely high concentrations of phthalate plasticisers which allegedly pose a risk to human health and the environment”. The organisation wants the European Union to ban the use of phthalates in sex toys as it already has done with phthalates previously used in the manufacturer of PVC childrens’ toys.

The Daily Telegraph reports how, “The environmental group said it was shocked to find that seven of the eight sex toys it had tested contained between 24 and 51 per cent of phthalates.”

Their actual report shows that individual phthalates in a range of products are at at trace amounts. They do report the presence of 490 g per kilo of di-isodecyl phthalate (DIDP) in one device as determined by GC/MS.

There is so much disinformation about phthalates on the web, that it is almost impossible to track down the actual levels of additives used as primary plasticisers in PVC products. I’d assume the percentage needs to be relatively high to make the devices we’re currently discussing “plastic” enough, but 51% seems very high regardless.

Moreover, where are the tests revealing how much of this “shocking” percentage might actually leach out of such a device during normal usage? And, even if there is a degree of leaching, does that correlate with actual risk to health. These questions are yet to be answered for any devices whether sex toys, children’s toys or medical devices.

Any thoughts?

Dark side of matter

“There really is dark matter out there,” says Dennis Zaritsky of the University of Arizona talking of the first evidence for this elusive cosmological substance, “Now we just need to figure out what it is.”

It was side-on views of two merging galaxy clusters made with state-of-the-art optical and X-ray telescopes that allowed Zaritsky and his colleagues to make this startling discovery. Dark matter is matter that does not emit or reflect enough electromagnetic radiation to be observed directly. Astronomers have assumed since the 1930s that most of the Universe must be composed of dark matter because of the way galaxies move through space. Our present understanding of gravity implies that the Universe must contain five times as much dark matter as normal matter.

Read the full story in my Spotlight physical sciences column on Intute.

Lethal bird flu virus

Although H5N1, the avian influenza virus, darling of a scare-mongering media is lethal. No doubt about it. It’s just that at this point in human history, this virus is not in a human transmissable form, thankfully.

Now, a new study of patients who became infected with H5N1 in Vietnam has revealed clues as to why the virus is so lethal.

Menno de Jong and colleagues compared viral levels and effects on the immune system in one group of patients infected with H5N1 and another group infected with two types of human flu virus. The patients with H5N1 infection had much greater viral load in the throat than the patients infected with the human virus; markers of viral load were highest in the H5N1 patients who died. Virus could also frequently be detected in the blood of H5N1 patients but only in those who died.

The authors found that H5N1 virus at high levels triggers the release of inflammatory cytokines and that levels of these compounds is associated with a higher viral load. Fatal H5N1 infection was also associated with a loss of white blood cells in the peripheral blood.

The authors posit that H5N1 replicates much faster than human flu virus and that the high levels of the virus trigger an overwhelming inflammatory response that contributes to lung dysfunction and eventually death. They report their results in Nature Medicine today.

An important point that should be made is that the lower virulence of human flu is the mechanism by which this virus has remained endemic in humans and infects millions year in year out. If it were highly virulent, like H5N1, it would kill too many hosts to be persistent year in year out. As a dead host cannot infect another in the same way as a living one in direct contact. It is not necessarily true that H5N1 will mutate immediately into such a persistent viral sub-strain. The likelihood is that it will mutate into a fast-infecting form initially, but such a form will remove hosts from the ecosystem too quickly to remain endemic in the way that common human flu is. Viz, we don’t see the 1918 flu today because it died out.

Sun, Sun, Sun

Girl Sunbathing There has been a lot of discussion over the summer as to whether we should all be getting a bit more sun to boost cancer-fighting vitamin D levels. That argument coupled with revelations that suntan creams might themselves boost the risk of skin cancer all fly in the face of the contrary view that we should be staying in the shade.

One thing the sun worshippers and those of tan-free skin agree on – getting sun burn is no fun. Now, researchers in England (A country fabled for its sunny climes) are giving volunteers a tan in a bid to find a treatment for sunburn. Anna Nicolaou of the University of Bradford, in the renowned sunspot of the North of England, is examining the biological mechanisms underlying sunburn and why it particularly affects people who don’t get a “good” tan.

The research team hopes to discover whether melanocytes that do not actively produce melanin discharge inflammatory mediators, including pro-inflammatory hormones called prostaglandins, which cause the redness, irritation and swelling of the skin that is observed in sunburn. They also hope to discover why people who tan easily are less likely to develop sunburn, contrasting to pale-skinned people who tend to sunburn easier.

You can find out more via the Bradford U press site.

Meanwhile, at the other end of the beach.

A new light-activated ingredient that mops up damaging iron could help reduce the effects of sunburn, according to research published in the Journal of Investigative Dermatology by UK scientists.

‘When skin is exposed to high doses of sunlight, such as when you are sunbathing, a massive amount of free iron is released in skin cells,’ explains Pourzand, ‘This free iron can act as catalysts for the generation of more harmful free radicals that cause severe cell damage.”

The net effect of mopping up iron released as the skin burns, is to reduce inflammation and pain, which are exacerbated by iron, and to prevent the build up of free radicals, which have been linked to an increased risk of skin cancer.

The researchers, Charareh Pourzand of the University of Bath and James Dowden, now at Nottingham University, are currently testing prototypes of the ingredient in the lab using three-dimensional human skin cultures and anticipate trialling the ingredient with human volunteers in the next two to three years.

Find out more at the Bath U press site

Avoiding spam filter false positives

A lot of email correspondents have been calling up recently to tell me their messages were getting trapped by my spam filter. To be honest, I didn’t even know it was enabled until the first call. It’s been tweaked now so should be okay, but here’s a Top Ten Tips list on how to avoid tripping the spam filters on this and other systems.

Of course, if you’re trying to send me spam, these tips won’t work as they simply cannot be followed if you’re intent on selling me a Rolex watch or getting me rich quick…

Pink Floyd, Sir Isaac Newton, and the missing indigo

First posted 2006-09-06. Updated 2023-01-23

2023 is the 50th anniversary of Pink Floyd’s “Dark Side of the Moon”. You’ll know it instantly from the cover art which shows a prism splitting a ray of light into a rainbow. I grew up with this album, but I must admit I didn’t remember noticing that the rainbow has just six colours. Don’t we normally think of rainbows as having seven – red, orange, yellow, green, blue, indigo, violet?

Interestingly, the six-colour rainbow has been a pride symbol for the LGBTQ+ community for many years. I wondered why that it didn’t have all seven colours either…was it something to do with the suspicion that confirmed bachelor Sir Isaac Newton was maybe gay? Probably not.

Anyway, the Floyd recently updated their socila media logo. The logo features the six-colour rainbow motif, just like the original album artwork. It triggered a load of bigoted comments and ignorant trolling [for which read: free publicity]. The trolls hated that their Pink Floyd had gone all “woke”. Well, aside from the fact that being woke is not a bad thing, the Floyd were woke long before anybody used that word to mean tolerant and accepting. Indeed, the whole album is lyrically about as woke as you can get without propping your eyelids up with matchsticks and wrapping yourself in a rainbow flag, and shouting “right on!”

But, trolls will be trolls, the endless antiwoke and bigoted bile spat out about the new artwork and the rants from people saying they will never listen to the band again is just incredible.

Better antifa than antiwoke I say. Shine on!

Original Post

Everyone knows the song…

Red and Yellow and Pink and Green, Orange and Purple, and Blue…

Not exactly the best mnemonic for recalling the rainbow, that purple should be “violet” after all, and then there’s the little problem of “pink”!

Much better is my late mother’s VIBGYOR (violet, indigo, blue, green, yellow, orange, and red) as cited in Newton’s famous prismatic experiments. Although some people prefer Richard of York gave battle in vain.

There is a problem. Where is this indigo? Can anyone really distinguish between violet and blue? To my eye, there certainly isn’t a jeans-coloured slice in the spectrum, and as chemist M. Farooq of the University of Karachi in Pakistan suggests this isn’t due to limitations of the prism. An article in the American Journal of Physics (1972, vol 20, p 526), he points out, drew attention to the fact that indigo does not exist in the spectrum some years ago and that instead was nothing more than one of Newton’s “preconceived notions”.

According to that AJP paper, Newton adapted the colours of the artist’s wheel – red, orange, yellow, green, blue, violet, and purple and then added something from his religiosity and his alchemistical bent. The number 7 after all is more heaven than the 6 of hell. Newton gave us the seven colours of the rainbow not because there are seven but because it fit his view of God’s universe better.

The indigo of our mnemonic is actually violet, and what Newton referred to as violet is probably what we call purple. Of course, purple is not present in sunlight but is a colour of mixed pigments on the artist’s wheel. More to the point though, there aren’t just seven colours. The electromagnetic spectrum is just that a spectrum, a continuous spread of hues in the visible and beyond.

All that said, some people do see seven “main colours” when prompted, some people do see a colour between purple/violet and blue in the rainbow.

Meanwhile, here’s the tech bit from the US National Bureau of Standards showing the range of wavelengths of light corresponding to the colour:

400-465 nm violet
465-482 nm blue
482-487 nm greenish blue
…
…
597-617 nm reddish orange
617-780 nm red

It’s all very well laying down the colourful law like that, but your idea of “reddish” might be slightly different from mine, in fact I might see orangey-red when you perceive reddish-orange (maybe it’s another example of the ambiguity in art I discussed recently in this blog). Moreover, as John Denker points out, there is a “band” between yellow and green that if the word chartreuse is in your vocabulary you might label it as such. “The question is not whether the band is there, but whether the observer chooses to take notice of it,” he says. “This whole colour-naming issue depends relatively more on cultural and behavioural factors, and depends relatively little on physics,” he adds.

On the same discussion group Thomas O’Haver of the University of Maryland asks, “Is there really in value in having students memorize something like this?”

It still doesn’t help much with the words of that song, though, Red and yellow and pink and green…