|SCIENCE & TECHNOLOGY|
Phasing out halons
that deplete ozone
iMac has shrunk, and how!
Mutations and high background radiation
NEW PRODUCTS &
Phasing out halons
that deplete ozone
HALON phaseout in the country is a combined effort of manufacturers, users, legislative and research, insurance and fire authorities, due to which the production and consumption of this ozone-depleting substance has been reduced from 750 mt per annum in 1991 to almost nil in 2004.
Besides the National Halon Reclamation and Banking Facility, which Union Forests and Environment Minister A. Raja inaugurated in Delhi on Tuesday, India has implemented 13 projects for phasing out halons in the consumption sector. Regulations were enacted and incentives provided to the domestic industry to follow ozone-friendly path.
This has ensured phase out of about 100 tonnes of production and 400 tonnes of consumption of halons as per the baseline year.
Now, no new halon-based fire extinguishing equipment is being produced.
Halons were known as miracle fire extinguisher chemicals. Unlike conventional agents like water, carbon dioxide and dry powders, that extinguish fire by cooling or shutting out oxygen, halons control fire by producing bromine radicals, that interfere with chemical chain reactions, propagating fire and explosion and extinguishing it within seconds at low concentrations.
These clean non-toxic agents were used the world over for efficient fire fighting measures. However, their harmful effects on the environment were then not known. One kg of halon in the atmosphere can destroy between 240,000 kg and 800,000 kg of ozone.
The ozone-depleting properties of the CFCs created global alarm in 70’s and early 80’s, leading to global caution in the form of the Montreal Protocol in 1987. However, bromine atoms in halons are even worse ozone-depleting substances. The ozone depleting effect of Halon-1211 is three times that of the CFCs. Halon-1301, having the ozone depleting property of 10, is one of the most potent ozone depleting substance known. Halons were brought under the control of the Protocol as Group II of controlled substances.
India had set up two plants for the manufacture of Halon-1211 and Halon- 1301, which were later closed. After joining the Montreal Protocol, India started implementing the programme for phasing out halons.
The recently introduced facility in Delhi will now pool the existing halon and effectively mange it only for essential purposes. Export and import is allowed only for recycled halons and all halon-based fire extinguishers and fixed fire protection systems are controlled and limited to critical use.
The four main objectives
of this programme are to prepare a comprehensive database of
Halon-1211 and Halon-1301 kept in stock by users like the ONGC and the
NTPC; to establish laboratory and other facilities for purification
and reclamation of halon kept in the stock for a long time; to prepare
educational material for training users for better management of halon
in their stock; and to establish a panel of experts to determine the
essential use of banked halon.
iMac has shrunk, and how!
THEY used to fill entire floors of buildings and were so costly that only governments or large companies could afford them.
Apple Computer has now shown just how far technology has come when it unveiled the new version of its iMac computer - which squeezes the entire machine behind a two-inch-thick flat screen that hovers above the desktop.
The new iMac G5, named for the chip powering it, will be available worldwide from the middle of this month (September), said Phil Schiller, Apple’s head of marketing who showed the machine at a show in Paris.
"With the entire system, including a 17- or 20-inch display, just two inches thin [sic], a lot of people will be wondering ‘where did the computer go?’" Mr Schiller said.
It’s not just the computer that has shrunk; the price has too. Starting at £ 919, the new iMac is cheaper than its predecessor, which was phased out in July. And in historical terms, it has as much processing power as a Cray-2 supercomputer of 1985, which could manage about 1 billion calculations per second ("gigaflops") but required a cooling tower and measured 1.3 metres around, and cost around £ million apiece.
Apple however expects that iMac G5 buyers will be the same household and small business buyers who made its original blue gumdrop-shaped iMac a hit in 1997. That turned the company’s fortunes around, and incidentally inspired an industry of semi-transparent household objects, while making its designer, the British-born Jonathan Ive, a star among his peers. Seen side-on, the new iMac looks like a giant sibling to the company’s iPod digital music players, floating above the desktop on a sturdy aluminium stand on which the screen can pivot.
But it is also weighty: the machine weighs 18 lbs (8.2kg), packing in a hard drive, up to 2 gigabytes of RAM, a DVD-burning drive, the power supply, and wireless networking.
However Apple yesterday
concentrated on its elegance. "If you use a wireless keyboard and
mouse, you only have to plug one wire in — the power," said Mr
Schiller. ——-By arrangement with THE INDEPENDENT, London
Mutations and high background radiation
THE natural background radiation at any place is due to radiation from outer space (cosmic rays) and that emitted by radioactive elements such as potassium-40, uranium and thorium present in soil. Large populations in certain parts of Kerala are exposed to high levels of natural radiation primarily because of the presence of monazite (thorium ore) in soil.
Scientists have tried to identify health effects of radiation in populations living in high background areas. Radiation can cause mutations in all parts of the cell, including the mitochondrial DNA, which the individuals inherit only from their mothers.
Dr Lucy Forster and her team found 22 mitochondrial DNA mutations in individuals from the high radiation areas and one in persons from areas of low radiation (Proceedings of the National Academy of Sciences, PNAS, 2002). The mutations tended to be located in DNA regions that are known to undergo mutations more often.
Media covered the paper extensively as the authors, during interviews, suggested that people who are exposed to even low levels of radiation may be at risk of cancer. BBC headline was "cancer risk for radiation workers".
Responding to my queries, Ray Dunne, Health reporter, BBC news online agreed that BBC did not suggest that that was the conclusion of the original research. The agency focused on it as it was of more relevance to more people. I argued that BBC’s comment was purely speculative; the authors themselves did not refer to it in their paper.
A mutation to manifestation of cancer involves several steps, I argued. "BBC online was not particularly interested in the evolutionary aspect of the study", Dr Peter Forster, one of the authors agreed. I felt that BBC, like other news agencies, had compulsions to make the story appealing.
I sought the views of Prof K.Sankaranarayanan, Professor Emeritus, Leiden University Medical Centre, The Netherlands. (He wrote all the reports on genetic effects of radiation for the United Nations Scientific Committee on the Effects of Atomic Radiation). According to him, at the current state of knowledge, we cannot attach any importance to these mutations from the standpoint of adverse health effects at low doses of radiation.
While talking to the media, Dr Peter Forster had suggested that based on this study, "it might be worth considering whether to lower the allowed limits for radiation workers of reproductive age".
"It is premature to try to draw any conclusion concerning cancer risk from the study, let alone to call for a reduction in dose limits etc"... "After all, our risk estimates (which form a part of the basis for dose limitation) are computed from epidemiological data on populations exposed to radiation - in other words, although we may have been unaware of this particular mechanism, its contribution to the total risk due to the combinations of mutations is already taken into account, automatically", Dr Jack Valentin, a geneticist and Scientific Secretary of the International Commission on Radiological Protection- the agency which recommends dose limits, clarified in reply to an e-mail message from me.
The PNAS paper noted that earlier studies in the high background radiation areas of Kerala did not reveal significant abnormalities in the local residents. Dr. Krishnan Nair and his colleagues from the Regional Cancer Centre and others did not see that cancer occurrence is consistently higher because of external gamma radiation exposure in the monazite areas (Radiation Research, 1999). I brought this information to the notice of Dr Forster. In response he stated that they knew about this paper; but for some reason forgot to cite it. PNAS paper did not really lead to radical conclusions on the impact of low levels of radiation on human beings.
Dr K.S.Parthasarathy is currently DAE/BRNS Senior Scientist and formerly Secretary of the Atomic Energy Regulatory Board
Has the discovery of quarks challenged the idea of quantisation of charge?
Naked quarks have not been seen separately. No one has seen or discovered a particle of 1/3 or 2/3 the charge of an electron. On the other hand many properties of particles that have been discovered — as also the results of their interaction — are understood if quark-like particles form their constituents. One could almost say that quarks are powerful theoretical constructs that have proved to be extremely useful in understanding the real universe. It is possible that free quarks make their appearance at energies not yet achieved by accelerators. Quantisation of charge will not be abolished even then. We are still talking of discrete charge values, even though fractional.
Can I know the relation between astronomy and astrology? Can we say that an astrologer is an astronomer?
This would need a slightly long answer. But in short I can say that even though origins of astrology and astronomy may have been the same, today astrology has little to do with astronomy. In fact astrology is not a science at all but preys on the human need for sustenance and support when in trouble, on his greed, or for transferring the responsibility of failure onto stars and fate. Astronomy is a vibrant science today and rejects supernatural influence of planets, an influence that goes against all known laws of nature.
Why does the sky have only blue colour and not the other despite the seven colours of the rainbow?
What we normally call the sky is
nothing but the light that comes to our eyes after being scattered by air
molecules. If there were no scattering of light by air we would not see any
sky. We would see only stars studded on a black firmament. This is precisely
what the sky looks to astronauts in space. The blue colour of the sky comes
from the fact that scattering by air increases rapidly as the wavelength of the
light decreases. Blue represents the short wavelength end of the visible light
spectrum. This is well understood physically. I might also draw your attention
to another commonly observed fact, namely that the setting and rising sun looks
orange. The reason for this is the same that makes for a blue sky. The shorter
wavelengths of light are preferentially scattered away while passing through
the thick layer of the atmosphere. This leads to predominance of longer
wavelengths, namely the orange and red, in the light that comes to our eyes
from the sun’s disc.
USING pulsed lasers, researchers have coaxed the metal nickel to self-assemble into arrays of nanodots — each spot a mere seven nanometers (seven billionths of a meter) across — one-tenth the diameter of nickel nanodots and on par with the world’s smallest.
Because the method works with a variety of materials and may drastically reduce imperfections, the new procedure may also bolster research into extremely hard materials and efforts to develop ultra-dense computer memory.
The researchers are working with an industry partner to apply the technique to development of next-generation light-emitting diodes (LEDs) - the small, bright lights seen in traffic signals and luxury automobile brake lights. The experimental LEDs are already more efficient than existing devices, potentially lasting decades and using a fraction of the power of fluorescent bulbs.
Jagdish Narayan and Ashutosh Tiwari, both of North Carolina State University and the National Science Foundation’s Center for Advanced Materials and Smart Structures, invented the new materials and manufacturing processes.
They announced their findings in the September, 2004, issue of Nanoscience and Nanotechnology.
Some window coatings reflect heat. Unfortunately, they also keep out the sun’s warmth when outside temperatures are chilly. Now, chemists in England have created a window coating that automatically transforms into a heat mirror only when warmed above room temperature.
The material is made of vanadium
dioxide imbued with traces of tungsten. Compared with clear glass, the film in
its heat-reflecting state could reduce by up to half the amount of room heating
due to infrared radiation, estimates Ivan P. Parkin of the University College
London. He and Troy D. Manning of Liverpool University in England describe
their new coating in the Aug. 11 Journal of Materials Chemistry.