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| SCIENCE TRIBUNE | Thursday, December 7, 2000, Chandigarh, India |
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Do not ignore your body clock
Making plastics from plants
Science Quiz |
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Do not ignore your body clock CYBER world has opened a 24-hour revolution to us. You can buy groceries at midnight, book your holiday on the Internet at any time and deal in shares online sitting at your home. And, as business hours get longer, we are lured into adopting unorthodox work and leisure patterns. But, a primitive timekeeper tucked deep inside our brains stubbornly defies these new trends. This body clock not only dictates when we sleep, but also keeps every cell and tissue working under a tight regime. What time we eat, rest and play, the rhythmic surge of hormones, the cycling in body temperature — all are in the clock’s domain. Yet it is surprisingly easy to outsmart our body clock with the help of alarm clocks. We do so almost daily without giving it a second thought. But scientists are warning that we ignore this biological timepiece at our own peril. Fighting our natural sleep tendencies to conform to work, family and social pressure may be grinding away at our health, triggering a string of maladies, from niggling aches and pains to more sinister problems such as heart disease, perhaps even the full-blown symptoms of chronic fatigue syndrome. Giving up the late nights and weekend lie-ins in favour of a regular bedtime might be as important to our health as quitting smoking or cutting back on saturated fat. From its headquarters in the suprachiasmatic nucleus of the hypothalamus, the biological clock controls every circadian rhythm in the body. “Anything you care to measure will show a rhythm — hormones, temperature, alertness, immune factions, urine excretion, sodium, potasium”, says Simon Folkard, a chronopsychologist at the University of Wales, Swansea. The clock’s job is to synchronise all these. The settings of our clock determine whether we are early rising larks or night owls. At genetic level too, one of the human genes involved in circadian rhythms has revealed that a single nucleotide change can predict whether a person tends towards being a morning (early riser) or an evening (night adept) type. But Folkard is convinced that tampering with the clock’s natural settings is a hazardous activity. It causes a constellation of symptoms: heart trouble, indigestion, ulcers, gut complaints, back and muscular pain, fatigue and frequent viral infections. How can disrupting the brain’s sleeping habits disturb the body in so many different ways?. Hervey Moldofsky, director of the centre for Sleep and Chronobiology at the University of Toronto, maintains that we are organised by interconnected rhythms. Moldofsky has observed dramatic changes in the immune system between waking and sleeping. Natural killer cells circulate in greater numbers during the day, while T cells are more active at night, and more of the immune regulator interleukin-1 is churned out as we sleep. Moving the clock settings to and fro disturbs this harmony, paving the way for the infections that often plague night shift workers. Even our metabolic responses to food are under the influence of the clock. Linda Morgan from the University of Surrey has observed that upsetting of person’s natural circadian settings will help keep his levels of glucose and some lipids in the blood dangerously high after a meal-which may explain why cardiovascular disease is number one hazard in night shift workers. “People have to accept that they are designed to be members of a day time species”, say Folkard. But not everyone is at equal risk from these disruptions. Surprisingly, morning types endure the punishing schedule of late shifts better and suffer fewer physical problems than evening type. According to Folkard, it all boils down to how easy it is to reset a person’s internal clock. Morning types enjoy a stable endogenous clock which needs no tuning because its cycle is almost bang on 24 hours. Even on night shifts their clock remains beatifically constant. Evening types, on the other hand, can easily change their clock settings, because their circadian cycles are longer than 24 hours and need resetting daily. But adjusting and readjusting to peculiar timetables land them in trouble. Everyone has an optimal time for sleep, and sleeping and waking at wrong point within the cycle can have dire consequences. Ignoring the pull of our endogenous rhythms will lead to more than just grumpiness. It could result in physical and mental exhaustion, like that seen in the elusive Chronic Fatigue Syndrome (CFS). At a recent meeting in London, chronobiologist Jim Waterhouse, from Johan Moores University in Liverpool discussed the theory that a disoriented biological clock may perpetuate illness. He and Gareth Williams, a clinical endocrinologist at Johan Moores University, have traced CFS patients temperature and hormone rhythms. As bedtime approaches and over a period of an hour or two, healthy people’s body temperature drops sharply. At the same time, the pineal gland in the brain pumps out melatonin, the sleep-inducing hormone. This combination is the signal that triggers sleep. In people who nod off easily, the two events are tightly synchronised, but in chronic fatigue patients they are mismatched. “In CFS patients, the normal relationship between temperature rhythms and melatonian secretion is lost. It looks like there’s a problem in the overall regulation of the body clock”, says Williams. If erratic behaviour has the potential to loosen the cogs in the biological clock of chronic fatigue patients, can a regular lifestyle tighten them up again? Many clinicians believe so. Cognitive behaviour therapy, which encourages patients to lead a routine-driven life, helps up to 80 per cent recover. Getting up at a fixed time and spending half an hour doing gentle exercise might help retune a lot of things, including the biological clock. Thus, after millions of years of evolution, we cannot suddenly ignore the body clock and become member of the 24-hour society without incurring penalties. The writer is from the Department of Mycology and Plant Pathology, Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan. |
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Making plastics from
plants EVERYONE is increasingly aware of the need to act more responsibly to make human developmental activities sustainable so that resources left for future generations are not depleted by the development taking place today. This is crystallized in the drive for “sustainable development” — acting in a way that does not limit the range of economic, social and environmental options available to our grandchildren. Sustainable development represents the simultaneous pursuit of economic development, environmental protection and social progress. Plastics are committed to making a substantial and positive contribution towards all the three dimensions of sustainable development like promoting economic development through jobs and wealth creation, applying both established and innovative polymer technologies to conserve resources and reduce atmospheric CO 2 — the key environmental challenges, and finally combining the exceptional properties of plastic with advances in information technology and medical science to provide better access to education and healthcare for all. Manufacturing plastic in petrochemical factories consumers about 720 million tons of oil and gas every year worldwide. Fossil fuels provide both the power and the raw materials that transform crude oil into common plastics such as polystyrene, polyethylene and polypropylene. Known global reserves of oil expected to run dry in approximately 80 years, natural gas in 70 years and coal in 700 years, but the economic impact of their depletion could hit much sooner. As the resources start diminishing, prices will pop up. In view of the fact that petroleum, a finite resource, is the basis for polymers known as plastic and that primary dependence on petroleum has caused disbeliever to call the manufacture of plastics unsustainable. This encouraged the industry to explore manufacturing processes that substitute renewable resources — such as plants — for petroleum. Thinking of plants as renewable resource for plastics is unbelievable but it is true that plants can be used for manufacturing plastics. Growing plastics in plants would be green in two ways: it would be made from a renewable resource, and it would eventually breakdown, or biodegrade, upon disposal. There are three main approaches for making plant derived plastics: converting plant sugars into plastic, producing plastic inside microorganisms, and growing plastic in corn and other crops. In the first approach, plant sugars are converted into plastics with the help of microorganisms. Sugar is extracted from the corn or other plants and is then transformed into lactic acid by the microorganisms. Lactic acid molecules and chemically linked into chains of plastic called polylactide (PLA). Polylactide has characterstics analogous to polyethylene terephathalate (PET), a petrochemical plastic used in soda bottles and clothing fibers. PLA also bear a resemblance to clear polystyrene, provides good aesthetics (gloss and clarity), but it is firm and fragile and needs modifications for most practical applications (i.e. plasticizers increase its flexibility). It can be processed like most thermoplastics into fibers, films, thermoformed or injection molded. PLA is used for compost bags, plant pots, diapers and packaging. If composted properly it takes 3-4 weeks for complete degradation. The first stage of breakdown (two weeks) is a hydrolytic reaction yielding water-soluble oligomers and lactic acid. The latter, as a naturally occurring substance, is rapidly metabolized into CO2 water and biomass by a variety of microorganisms. The second appraoch for making plant derived plastics is producing plastic inside microorganisms. The plastic produced is called polyhydroxyalkanoate (PHA). In the case of PHA, the bacterium Ralstonia eutropha converts sugar directly into plastic. PHA naturally accumulates within the microbes as granules that can constitute up to 90% of a single cell’s mass. However, in the case of first approach for making plastic, a chemical step is required outside the organism to synthesize the plastic. PHAs are generally suitable for extrusion, injection molding, as well as film and coating applications. PHAs may also be suitable for biomedical use for example in long-term drug delivery or orthopedic repair. In addition, the PHAs have a number of performance attributes like excellent barrier properties, low temperature thermolysis etc. PHAs are biodegraded by a wide range of microorganisms, and recycling or hydrolysis can also manage them. The costs of PHAs have been higher than for petroleum-based plastics, limiting their application to certain niche markets. Third approach is growing the plastic in plants. Modifying the genetic makeup of an agricultural crop so that it could synthesize plastic as it grew would eliminate the fermentation process altogether. Instead of growing the crop, harvesting it, processing the plants to yield sugar and fermenting the sugar to convert it to plastic, one could produce the plastic directly in the plant. Transferring the genes necessary to synthesize PHAs from a bacterium called Ralstonia eutropha into the plants can do this. These particular PHAs, however, are too brittle to be worthy of the name “plastic”, so a second gene has to be transplanted from another bug, Escherichia coli. The E.coli gene is there to boost the produciton of a molecule called propionyl-CoA. When plugged into the biochemical pathways that make PHAs this, together with its already plentiful sister molecule acetyl-CoA, modifies the synthesis to produce a more plastic. PHA molecule. In order to avoid competition between the plastic production and food production, researchers targeted part of the corn plant that is not typically harvested-the leaves and stem together called the Stover. Growing plastics in stover would still allow farmers to harvest-the leaves and stem together called the Stover. Growing plastics in stover would still allow farmers to harvest the corn grain with a traditional combine; they could comb the fields a second time to remove the plastic containing stalks ald leaves. This would enable both grain and plastic to be reaped from the same field. Recent research, however, has raised doubts about the utility of these approaches. The biodegradability of the plastics obtained from above mentioned approaches has a hidden cost and the biological breakdown of plastics releases carbon dioxide and methane (heat-trapping greenhouse gases that international efforts currently aim to reduce). So fossil fuels would still be needed to power the process that extracts the plastics from the plants, an energy requirement that is much greather than anyone had thought. Successfully making green plastics depends on whether researchers can overcome this energy consumption obstacles economically-and without creating additional environmental burdens. In the third approach achieveing both a useful composition and high plastic content in the plant turns out to be difficult. The chloroplast of the leaves has so far shown themselves to be the best location for producing plastic. But the chloroplast is the green organelle that captures light, and high concentration of plastic could thus inhibit photosynthesis and reduce grain yields. So the advantage gained in substituting the renewable resource for the finite one is lost in the additional requirement for energy. Regardless of the particular approach to make plastics, energy use and the resulting emissions constitute the most significant impact on the environment. In light of this fact, it is proposed that any
scheme to produce plastics
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Paranoid about power breakdowns, Masatoshi Iquchi, a 64-year-old insurance representative from Nankoku, on the Shikoku island in Japan, has fitted tray upon tray of solar panels upon his roof so that he would not be left groping in the dark if the power ever failed. But now, after having done that he is faced with a very unusual situation. The solar panels which heat and light up his home produce so much electricity that he has been forced to sell the excess power to the Shikoku Power Company. The panels, which cost 800,000 yen to install have now become such a rich source of income that he is planning to retire from his insurance job and sit back and enjoy the fruits of his sensible investment. The electricity company pays him 275 yens per 10 kilowatt hours and with the amount of spare power he has, he makes 50,000 yen a day making him a wealthy man. But Masatoshi is a worried man nonetheless. Following his example a number of other people are following suit and soon he fears there will be a price war with people ready to sell power at much lower rates than him!
New discovery on ozone layer Researchers have developed a new superconductive detection system which can be used to explore the ozone layer. Using the superconductive detection system they discovered that the ozone layer contains much more chlorine monoxide — which breaks down ozone — than models had predicted. The system, developed by the NWO’s Space Research Organisation Netherlands (SRON) and the University of Bremen (Germany), uses a mini-aerial. Molecules in the atmosphere emit high-frequency signals from which qualitative and quantitative information can be extracted. The mini-aerial receives these signals and researchers can then look for the specific signals which show the presence of chlorine monoxide, which is a major intermediary product in the breakdown of the ozone layer. The signals emitted by chlorine monoxide are at a frequency about one thousand times that of the television waveband, meaning that tiny aerials are needed to receive them. The new system makes use of “waveguide detectors” which are superconductive at a temperature of almost -273 degree celsius. The detectors are only few micrometres in size and are contained in a piece of equipment the size of three refrigerators. The measurements are carried out from a plane flying at an altitude of 12,000 meters. Full understanding of the chemistry of the ozone layer can be made if satellite measurements on a global scale are available. Currently, satellite instruments are not as sensitive as the Dutch-German detection equipment. In future, the new detection system can be used in satellites to study the ozone layer.
Harmful refrigerants A new integrated air-cycle air-conditioning system, claimed to be the world’s first, promises to eliminate the use of environmentally harmful refrigerants. The system, developed jointly by the Bristol University’s Food Refrigeration and Process Engineering Research Centre and Building Research Establishment (BRE) of the United Kingdom, use air as the refrigerant to provide heating and cooling from an integrated packaged unit.
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Science Quiz 1. Name the winner of this year’s Indira Gandhi Award for Popularisation of Science. 2. Recent studies have shown that consumption of “pan masala”, so commonly used by a large number of people in India, can lead to a condition called oral submucous fibrosis (OSF). Which disease is likely to reach an epidemic proportion in the next decade due to this reason? 3. FTP is a term used in computer technology and represents a fast way to upload or download files from one computer to another or from the Internet to a computer. What does FTP stand for? 4. Can you name four types of mammals which have the ability to learn to speak or sing? 5. When white light is passed through atomic or molecular vapours of a substance, the vapours absorb radiations of wavelengths characteristic of that substance, thus producing dark lines against a white background. What general name is given to such dark lines? 6. Asbestos belong to a group of naturally occurring minerals which are fibrous, very heat-resistant and chemically inert. These are used in the manufacture of chemical filters, fire-proof material, paper cardboard, building materials, astronaut suits, etc. What are these minerals chemically? 7. A slice from history of science! The equivalence between inertial and gravitational masses has been experimentally established to an accuracy of one part in 1011. Name the physicist who performed the first experimental test for this equivalence. Which device did he use for this purpose? 8. Suppose we have two Weston type galvanometers, which are connected to each other. If we hold one galvanometer in our hand and move it rapidly to and fro, then the needle of the other galvanometer shows an oscillating motion. What is the cause of electric current so produced? 9. These cells are produced in the bone marrow and enter the blood stream. What are these cells called which recognise and kill virus affected cells but do not produce antibodies? 10. A defence laboratory at Hyderabad is referred to as ANURAG. What is its complete name that has been abbreviated to read ANURAG? Answers 1. Prof Yash Pal, the well-known India physicist
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