Chandigarh, Thursday, October 8, 1998 |
Miracle of miniaturisation What turns
sport fans wild? All
in a tea cup |
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 worlds 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 tasters 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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