Chandigarh, Thursday, October 8, 1998
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Chandigarh, Thursday, October 8, 1998 |
Miracle of miniaturisation What turns
sport fans wild? All
in a tea cup |
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Miracle
of miniaturisation All around us, gadgets are becoming
midgets, thanks to the revolution in miniaturisation
ushered in by the transistor in 1948. RECENTLY, you must have read about how Mr Satish Gujral, the well-known artist and brother of the former Prime Minister, Mr I.K. Gujral, regained some of his hearing 62 years after he had lost it. This near-miracle was made possible by the cochlear implant, a tiny gadget containing 24 electrodes. The implant bypasses the defective cochlea, or inner ear, and directly excites a small part of the nerve bundle forming the auditory nerve that conducts sound to the brain. The cochlear implant is one of a host of tiny electronic gadgets that make life easier for handicapped and disabled persons. Another is the cardiac pacemaker, a cassettee-sized device that generates signals causing contraction of the heart muscles, just as those generated by the heart’s natural pacemaker do. The technology that has made possible such devices is miniaturisation, which means making things ultra-tiny. Miniaturisation is fast transforming our lives. Telephones, for example, have become so small that, in the form of cellphones, they can be carried in your pocket — often becoming a nuisance to others when they ring. The bulky radio sets of a generation back have been replaced by transistor radios and walkmans. The giant computers of the 1950s have been replaced by PCs and laptops. It all begun with the invention of the transistor in 1948. The transistor was so called because it transferred an electric current across a resistor. It was much smaller than the vacuum tube and needed only a fraction of the electricity. The transistor soon put the vacuum tube out of business. By 1960, engineers were able to crowd several transistors, as well as other electronic components on to a tiny silicon chip one-fourth square inch in area — the integrated circuit or IC. In the early transistor radios, miniaturisation was possible only by shortening the copper wires connecting the transistors or by using fine soldering irons. In the IC, all the components of a circuit could be assembled directly on the surface of a semi-conducting material like silicon or germanium. Thus, the IC achieved the separation as well as the interconnection of the various circuit elements electrically from within the semiconductor surface, rather than manually from outside. Labour and material were thus cut down. Also, rapid reduction in feature size and better performance became possible. A typical computer of the 1950s contained more than 4,000 tubes, six miles of wires and 100,000 soldered joints; it cost $ 500,000 and consumed 30,000 watts of power. In the integrated circuit chip, circuits could be measured in inches and covered by signals in an electronic blink. Hence, computers with ICs were faster as well as smarter. Integration Being designed for only one specific job, ICs required other electronic parts to keep them opening and closing in proper order. This was achieved in the late 1960s by the large-scale integrated circuit (LSI), which integrated a number of circuits with different functions on individual chips of about four square inches size. Each LSI contained 64,000 transistors. The next quantum jump in miniaturisation came in 1969 when M.E. Hoff of Intel Corp had the inspired idea of a general-purpose processor circuit that could be programmed for a variety of jobs. In 1971, Hoff was able to put all the logic circuitry of a calculator’s central processing unit on one chip. This one-chip central processor, or microprocessor, was advertised by Intel Corp as a "computer on a chip". The micro-processor contained 2,259 transistors in an area barely one-sixth inch by one-eighth inch. It could insert "intelligence" into many products for the first time. Today, a single such microprocessor can do the work of ENIAC, the world’s first truly electronic computer. Built in 1946, ENIAC used 18,000 vacuum tubes, any of which could blow out without warning. The microprocessor also consumed five million times less power than ENIAC. Micro-electronics began to pervade nearly every aspect of life, even creating new areas of activity. Even more than the transistor radio, it was the pocket calculator that brought micro-electronics to the common man. In 1965, the desk calculator was as large as an office typewriter; it ran on 12 volts and cost $ 1,200. The Pocketronic calculator, marketed in April 1971, had four functions, weighed 2½ pounds and cost about $ 150. Micro-miniaturisation has been the driving force of electronics during the last 45 years. It has given us hand-held calculators, digital wrist-watches, video games, artificial satellites, personal computers and robotic probes that survey the planets of the solar system. We are now in the age of large-scale integration, or VSLI, with feature sizes, in the most advanced devices, being about one micron, that is, one-millionth of a metre. Next generation devices will be ultra large-scale integrated circuits. The sixth generation Pentium Pro has 5.5 million transistors embedded in it. Beyond a certain point, however, there is a penalty for the shrinking in size. When transistors are packed tightly together, there is more electricity rushing about in the microprocessor. Some of this current leaks out, creating a sort of micro short-circuit which damages the silicon. There is also more heat generated. As the limits of micro-miniaturisation have been reached during the last few years, a technology called nanotechnology has been taking over "Nanos" is the Greek for "dwarf", but as a prefix is used to denote a thousandth of a million, that is a billionth. A human hair, for instance, is 10,000 nanometers in diameter, and light waves, about 100 nanometers. One way out is to use a material called gallium arsenide, which allows electrons to move more freely as it becomes. However, gallium arsenide is costly, brittle and harder to cut into wafers. Another way is to make transistors still smaller. Silicon chips have been made by passing ordinary light through a mask to transfer circuit patterns to a thin wafer of silicon which has been cut from a single crystal and coated with a light-sensitive film. However, light waves are too large to render sharp images. Hence, the use of shorter wavelengths like ultraviolet light, which has enabled the use of 500 nanometer size features. Scientists are now experimenting with X-ray lithography which, hopefully, will enable 4,000 million transistors to be crammed on to a single computer chip. Also being tried out is plasma processing. Here a gas inside a chamber is ironised, causing some molecules to release electrons. The result is a "plasma" or gas of positive ions and free electrons, in which the reactive atoms bind and remove silicon from the desired pattern on the wafer’s surface. Plasma processing is expected to predominate by the middle of the 21st century, after coming into commercial use by its beginning. Today’s chips are based on bulk materials. Even the thinnest wires on the fastest chips are thousands of atoms in diameter. As far back as 1959, the Caltech physicist Richard Feynmann had predicted that atoms could be arranged the way nuts and bolts were fixed on a machine. It is now possible to move individual atoms about by means of the scanning tunnelling microscope, which is so powerful that it can produce images of individual atoms. The microscope’s tip carries a small electric current which attracts molecules from a metal or semiconductor surface, just like iron filings to a magnet. Using the scanning tunnelling microscope, semiconductors would consist of just a few dozen atoms, measuring a few billionths of a metre. To make semiconductor devices even smaller, scientists are harnessing a technology called band-gap engineering which takes account of the fact that electrons are not merely particles but also waves. By sandwiching ultra-thin layers of a relatively good conductor like gallium arsenide between two layers of a relatively poor conductor like gallium aluminium arsenide, it has been possible to obtain nano-scale layers, channels and boxes, respectively called quantum wells, quantum wires and quantum dots. Quantum wells have already found their way into transistors in satellite microwave receivers and in the lasers in some fibre-optic communications systems. In quantum dots, electrons are confined to a single point rather than in a line or a plane. Quantum dots, being closer together, might lend themselves to computer chips 10,000 times more powerful than the best silicon devices of today. They might lead to massively parallel computer architecture, paving the way to computers that think like the human brain. Some groups are now exploring the possibility of connecting quantum dots into palm-sized computers, using chemistry to wire the dots together with long-chain molecules of certain conductive polymers, or compounds made up of repeated molecules. Techniques similar to nanotechnology could be used to assemble bigger objects like cars or skyscrapers. These would be assembled by tiny robots, successors to the scanning tunnelling microscope’s tip, that move molecules into clumps and clumps into cars or building components, all following a computerised plan. Eric Drexler, co-author of the book "Unbounding the Future", even predicts the day when assembly machines will even assemble themselves! According to Jon Roland, director of the Vanguard Institute in Redwood City, California, researchers may be able to custom-build simple molecules that can store and process information and manipulate or fabricate other molecules. Ushering in an age of abundance, this could well bring about what we may describe as the "end of economics". The biggest money-spinning applications of nano-technology are likely to be in medicine. Eric Dexler, in his book ‘The Engines of Creation’ (published in 1986) looked forward to sub-microscopic robots that would crawl through a patient’s arteries to scrape away fatty deposits that cause heart attacks or to hunt down cancerous cells. Making things tiny and "smart" is big business today. Many electronic watches integrate several functions such as calculator, programmable melody-playing alarms, blood-pressure monitor and digital thermometer. In the newest automobiles. microcomputers and microprocessors control fuel injection, ignition, seat belts and tyre-pressure sensore that release airbags when there is deceleration. Most of the nano-tech action is in the United States, which controls microprocessors, and in Japan, which controls memory chips. Nanotechnology could well be the second largest manufacturing sector in the world by the end of the next decade, excelled only by the computer chip industry. Today, we can make
computer chips in which events happen faster than in our
brain cells. The human brain is still the most efficient
computer. The ultimate in miniaturisation would be to
make a copy of the human brain. For this, we would need
to know how each synapse — the structure that
controls the movement of signals from one nerve cell to
another — is related to the two nerve cells it
joins. There are 100 trillion synapses in the human
brain. Some day, using nano-technology, it should be
possible to pack that much storage into a package the
size of a pea. |
All in a
tea cup NEXT to water, tea is the most popular drink in the world, truly "the cup that cheers". Tea drinking began in China in about 5th century AD and spread all over the world. Contrary to the popular belief, alcoholic beverages that man consumes act as "depressants" while the non-alcoholic beverages, chiefly tea, coffee, cocoa and cola, act as "stimulants". The stimulatory effect of these non-alcoholic beverages originates from the basic nitrogenous organic compounds called alkaloids, which are extracted from the source material along with their flavour by hot water. The active ingredient in tea is an alkaloid caffeine and some other closely related compounds. The word alkaloid conjures up visions of drug addiction, degradation and death in the modern society. However, the caffeine group is non-addictive and socially, economically and medically very important. Chemically, Caffeine is 1, 3, 7-trimethylxanthine, a compound synthesised by plants but not animals, as a branch of the same biosynthetic pathway in which nucleic acids are synthesised. Caffeine was first isolated in 1820 and its chemical structure determined in 1825. Although this chemical can be synthesised in the laboratory, isolation is cheaper than synthesis. Caffeine affects the human central nervous system as a mild stimulant, increases heart beat and is also believed to lower cholesterol levels in blood. In some people, its antisoporofic action can lead to insomnia or sleeplessness. A processed tea leaf contains up to 5% caffeine and 20% tannins (quinones), which, along with pectins and dextrins give astringency and colour to the beverage. An essential oil Theol gives the flavour and aroma, while the rest are cellulose and other structural materials. The evergreen tea plant known scientifically as Camellia sinensis has three sub-species; namely sinensis, assamica and cambodiensis. The young shoot with two leaves and a leaf bud, plucked manually, is the preferred plant part to be used for preparing a high quality brew. North-east India produces a wider variety of tea than any other area under cultivation in the world. From the Himalyan heights of Darjeeling (upto 6500 ft) descend the world’s most flavoury and therefore, the most expensive teas. On the other hand, from the plains of Brahmputra valley come the teas which are most attractive to look at, the richest to drink and longest to endure in freshness. This vast range of agroecological conditions and cross-pollinated nature of the tea plant have endowed this beverage with a vast variety in colour, aroma and flavour to suit different type of palate. The tea that most of us drink regularly is Black tea. Other types of tea manufactured are Green, Oolong and Instant. Green leaf is the raw material and fermentation is the central process of manufacture for all these varieties of tea. The preliminary chemical reaction is oxidation and condensation of tea catechins or tannins rather than anaerobic or bacterial fermentation. Black tea is made by rupturing the leaf cells to release enzymes and to expose them to oxygen. When the optimum fermentation is achieved, the leaf mass is passed through hot air to destroy enzymes and thus arrest the process. Green tea is made by destroying the oxidation enzymes just after the leaf is plucked so as to ensure that the tannins are unchanged rather than condensed as in black tea. Oolong tea, which is not made in India, is an intermediate between black and the green tea with regard to fermentation. Instant tea is soluble in water but like black tea requires fermentation. It is manufactured in South India. Now a days, the black tea is manufactured in basically two ways, Orthodox and CTC (crush, tear and curl). These two processes differ in the rate at which the fermentation of the leaf mass is allowed to proceed. In the CTC process, the accelerated and intensive fermentation results in the blackish brown and granulated form of prepared tea leaves which yield a much thicker liquid and more cups of drinking tea per kilogram. It is difficult to control plucking rounds when the tea bushes are flushing heavily. Fluctuation in tea quality is, therefore, unavoidable because of varying workload over the year in tea industry in north-eastern India. These factors are as much responsible for the need to blend tea as the botanical reasons mentioned before. The fluctuation in quality is mainly responsible for tea tasting and tea auctions based on the quality of each lot offered by the tea grower. Chemical analysis can help to determine various constituents of a tea sample but to judge it in its totality remains the taster’s monopoly. This quick assessment (up to 1000 samples a day) is based on the talent cultivated by years of training and experience. Of the five human senses, a tea taster has to use, simultaneously four. Trained sensitive taste buds, a keen nose and an encyclopaedic palate memory to compare the colour, strength and flavour of a tea sample with a number of teas he has tasted over the years is a must for a successful tea taster. The writer is from the
Department of Genetics, PAU, Ludhiana. |
by J. P. Garg 1. "To have nuclear weapons means to wage a war against the earth and elements, only to see our cities and forests burn for days and to live interminable nights after nuclear winter sets in." Who said this about the horrors of nuclear war recently? 2. Which planet of our solar system is not normally visible during day due to the intense glare of the sun but is seen clearly during total solar eclipse? 3. For minor ailments, we often clean our sore eyes with the benign solution of an acid in water. Which is this acid that is contained in the extract of "amla" fruit? 4. Which living chemical substances help the digestion of food in our body? 5. Arjun was a warrior in the epic "Mahabharata". What is "Arjun" in Indian defence system? What is "Arjun" in Indian agriculture? 6. "Silicon Valley" is an area in the USA near San Francisco where many computer and electronics industries are located. Name the city that is fast coming up as the "Silicon Valley" of India. 7. What is "Sagar Kanya"? What is "Sagar Samrat"? 8. Who invented matches for lighting? Which substance did he use on a splinter? 9. Bronze is the first ever man-made alloy. Of which metals is this alloy made? What is the importance of bronze in games like Olympics? 10. Doctors the world over might soon stop stitching up patients. Scientists have discovered a bio-adhesive which can rejoin not only skin tissue but also bones, tooth sockets etc. Which is this adhesive? Which Indian institute has developed the technology for its synthesis? ANSWERS 1. Booker Prize winning author Arundhati Roy 2. Mercury 3. Boric acid 4. Enzymes 5. A powerful battle tank; a variety of wheat 6. Bangalore 7. Indian Oceanographic Research Vessel; Indian Oil Exploration Rig in Bombay High area. 8. German scientist Jakob Friedrich Kammera; red phosphorus 9. Copper and tin; a bronze medal is awarded to the third position holder in an event 10. Amcrylate (isoamyl
2-cyano acrylate); Indian Institute of Chemical
Technology, Hyderabad. |
| H |
Bionic man "Life-like in motion, durable in construction, the nearest approach to nature in action. Satisfaction guaranteed.'' With these words one Jas. I Lyons of Chicago marketed his aluminium pneumatic feet - the latest thing in prosthetic design in 1894. Today, prostheses are still being marketed in these terms, but the reality of carbon fibre materials, microchip computer technology and modern surgical techniques have made 1990s prosthetic innovations like the ``dynamic ankle'' and ``energy storing feet'' a rather closer approximation of the natural world-enough, for instance, to allow users to run the 100 metres in under 12 seconds or climb the world's highest mountains. This is just one, relatively minor, area where medical science has revolutionised the possibilities for those requiring new limbs, organs or body tissue in the 1990s. The combination of advances in computer technology, material sciences, laser surgery, and the understanding of chemicals, genes, viruses and bacteria have brought us within reach of what were once seen as the wilder realms of science fiction. Culture has traditionally been suspicious of the artificially created being, of man usurping the powers of God to create life. From Mary Shelley's 1818 Gothic novel Frankenstein (about a man constructed from body parts) to Paul Verhoeven's Robocop (a mechanical being with a human brain), the artificial man has been either a figure generating fear and loathing or a soulless destroyer that can apparently be harnessed for good or evil. But now, for the first time, we are coming close to turning the fictions into reality and manufacturing a human; and the challenge for the medical and scientific world is to wean a sceptical public away from their fears and fantasies. Underlying the public's paranoia about science's ability to create a mechanical man - or worse an organic man - is the question of where that leaves humanity, the belief in the uniqueness of every being. As with cloning, the creation of tissue and the sophistication of mechanical limbs pose dilemmas about life and mortality, about what makes us what we are. As the bionic man of TV drama comes closer to reality, so the ethical arguments increase. Every new step into the unknown will be argued over: does it represent a dream of progress, or a nightmare of dehumanisation? Take, for instance, the claims of the eminent American brain surgeon, Dr Robert J White. Earlier this year he spoke of the possibility of conducting what he called ``a total body transplant'' - removing the head of one patient and attaching it to the body of another. A decade ago this kind of talk from a respected physician would have been dismissed as outlandish or downright silly, but no longer: he has already achieved it with monkeys - within limits. White says he has perfected techniques of minimising blood loss and reconnecting the major arteries, allowing one of the animals to survive for a fortnight with the ability to see, hear, smell, taste, breathe and eat. (Guardian) Light for the brain Our bodies have a rhythm, like sleeping and waking up, that is regulated by an internal clock which in turn is set by darkness and light.How does the brain set the internal clock? The retina of our eyes contains pigments, called opsins, which absorb light and transmit it, via the optic nerve, to the brain.Thus as far as the non-blind people are concerned the opsins are the means by which they regulate the daily rhythm of their bodies. But it is a known fact that even blind people have their daily rythms.What is the mechanism in their case? It now turns out that there are two more varieties of light-sensitive pigments, that have been named cryptochromes. They also reside in the retina, but not in the same areas as the opsins. They absorb only blue light and send their signals to a part of the brain outside the vision centre. Even more significant is the finding that unlike opsins, cryptochromes are found in cells all over the body. Leeches to cure varicose veins Medical researchers from KEM Hospital in Mumbai have used leeches to treat patients suffering from varicose veins, enlarged and distorted blood vessels commonly seen in the legs. The treatment, first described in the Ayurvedic text "Sushruta Samhita" in 2000 BC, involved the use of leeches to suck and draw out blood from such veins. Common symptoms of varicose veins are ulcer, oedema (an excessive accumulation of fluid in the cells) and hyperpigmentation, all of which can be reduced with the leech therapy. KEM researchers reported in the Indian Journal of Medical Research. The leeches used for the treatment are the medicinal variety. Hirudo medicinalis, which the KEM team collected from a local ayurvedic pharmacist. The treatment protocol was cleared by the hospital ethics committee. The KEM team comprising R D Bapat, B S Acharya, S Juvekar and S A Dahanukar applied leeches on 20 patients. According to them, leech therapy healed ulcers in all the patients and decreased oedema in 95 per cent cases. Other complications also reduced significantly. The conventional treatment involves limb bandaging which is costly and can cause allergic reactions. Clot-dissolving drug People who have had mild heart attacks or suffer from chest pain may be able to inject themselves with a drug to prevent a heart attack or chest pain, say U.S. scientists. Enoxaparin — a slimmed-down form of the commonly used clot-dissolving drug heparin — could help stifle a clot-forming protein that enters the bloodstream after the heart is damaged, according to the Journal of the American Heart Association. The release of clot-inducing proteins into the bloodstream continues months after chest pain or mild heart attacks. This new research might allow physicians to prescribe relatively unsupervised long-term self-administration of anti-clotting therapy, sort of an insulin-like injection for coronary artery disease, according to the study. By using enoxaparin,
researchers were able to control von Willebrand factor, a
"reactant" protein released into bloodstream
when blood vessels are inflamed or when a person has a
heart attack or chest pain. The scientists found
enoxaparin to be superior to heparin in controlling von
Willebrand factor. |
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