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| SCIENCE TRIBUNE | Thursday, May 31, 2001, Chandigarh, India |
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Electric vehicles hold
promise Safer drinking
water Nucleus in a
looking glass |
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Making vehicles
user-friendly The Supreme Court had earlier taken a serious view of the alarming air pollution in Delhi. Over 30 lakh vehicles in Delhi have been polluting the atmosphere with noxious emissions. In a bid to curb vehicular pollution, the Supreme Court had directed that all the diesel-run commercial vehicles should be changed to run on Delhi roads with eco-friendly CNG fuel. It has extended the deadline for conversion to the CNG fuel to September 30, 2001. The Centre for Science & Environment (CSE) has reported that the Indian air quality regulators had failed to develop precise strategies to phase in cleaner fuels and technology by taking into account health parameters of risk assessment. Its study has revealed that diesel fumes are more carcinogenic. It said that the cancer potency level of the exhaust from diesel vehicles in India is double that of petrol-run vehicles. It also said that the risk from diesel fumes is enhanced by their ability to trigger a wide range of non-cancerous effects, including allergy, asthma and other respiratory problems. A recent study in Australia has, however, shown that low-sulphur diesel (with 0.05 per cent sulphur content) along with oxidation catalyst is a better fuel than CNG (compressed natural gas) & LPG (liquefied petroleum gas). The unleaded petrol introduced earlier in Delhi for all vehicles to curb air pollution led to a controversy that unleaded petrol used in vehicles without catalytic converters will emit more poisonous gases like benzene. The Supreme Court then directed that petrol in Delhi should be made available with 0.05 per cent sulphur and 1 per cent benzene. The petrol used to contain 0.1 per cent sulphur. The damaging pollutants in the form of hydrocarbons, suspended particulate matter, nitrogen oxides, carbon monoxide, sulphur dioxide, lead oxide, etc, from industry and use of petroleum in automobiles have been polluting air and causing a number of diseases like lung cancer, asthma, bronchitis, etc. Eighty per cent of cancer is attributed to environment polluted with toxic and hazardous chemicals. Delhi is ranked fourth among the 41 cities of the world monitored for air pollution. Delhi tops in the country in lead emissions mainly be automobiles. A Delhi citizen has been accumulating higher quantity of lead in the body than the prescribed safe limit by the World Health Organisation (WHO). The two-stroke two — and three-wheelers consume 60 per cent of the total gasoline produced in India. The Supreme Court had directed the Union Government to determine the feasibility of using propane as an eco-friendly fuel in the vehicles as an alternative to petrol. Propane is being used these days in advanced countries. A majority of autos have not turned to propane because the conversion kit is expensive. To reduce vehicle pollution and to curb harmful lead emission, lead-free petrol was earlier introduced in the four metropolitan cities in 1995. But this was applicable to new vehicles, constituting hardly 10 per cent of the total motor vehicles. The old vehicles were not covered. As a result, situation on air pollution did not improve much. The Supreme Court then directed the Delhi Government to fit all its petrol-driven cars with catalytic converters to that these could be run on unleaded petrol. Since 1923, automobiles have been suing lead in the fuel to achieve better octane value for fuel efficiency. It has been later discovered that lead concentration in the atmosphere has been on the increase posing serious health problems, including damage to brain, kidney and other organs. Lead from automobile exhausts and industry accumulates in the form of dust. City road dust has been found to contain two grams of lead per kilogram of dust. Much worse, on inhalation, organic lead emitted from cars, gets easily absorbed in brain, liver, kidney and blood, which becomes cumulative poison leading to brain damage, muscular paralysis, convulsions and even death. People exposed to lead at work could also develop Alzheimer’s disease. Lead emission ranges from 1.0 to 16 ppm (parts per million) in big cities, which has doubled in the last one decade. The criteria of air quality as recommended by the WHO is 0.5 ppm. 50 per cent of Bombay City’s population contains 30 microgram of lead in 100 ml of blood; while 50 microgram is enough to cause brain damage. For this reason, leaded petrol has been banned in developed countries. Today, more than 70 per cent of the petrol used in the world is unleaded. But its use has also created a controversy as it contains higher levels of aromatic organic compounds, and its use releases higher quantity of benzene in exhaust emissions. The average benzene content in the UK petrol is 2-3 per cent. The European Commission limit is 5 per cent by volume. The German Government has recommended to reduce it to 1 per cent. The unleaded petrol used in France contains the highest levels of benzene and other aromatics. Benzene is carcinogenic. It induces leukamia. Italian toxicologists say that 50 cases of leukamia in every 1,000 are attributable to benzene in petrol. Italian National Toxicology Advisory Committee report says that 40 per cent of leukamia cases attributable to benzene emissions from petrol could be avoided by reducing the aromatics content to 30 per cent and the benzene content to 1.2 per cent by weight. The concentration of benzene in some European countries has been detected as high as 70 microgram (Milan) to 460 microgram (Naples) per cubic metre of air. In Germany, the benzene level in the blood of children in urban areas has been significantly higher. According to the WHO, there is a risk of four cases of leukamia per one million people on exposure to one microgram of benzene per cubic metre of air. There is no safe level for airborne benzene. European countries such as France, the UK, Germany, Italy and Greece have been using catalytic converters inside a car’s exhaust system to convert pollutants in the unleaded petrol to reduce benzene and other hydrocarbons. Noble metals like platinum, palladium and rhodium are commonly used as catalysts. The use of unleaded petrol in the automobiles without converters is a great risk to health and ecology, posed by benzene. Apparently, serious efforts are needed to create awareness among the consumers to make their vehicles eco-friendly to reduce emissions. There is also a need to exploit propane and other clean funds like CNG, ultra low sulphur diesel, etc, to suit our conditions. |
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Electric vehicles hold
promise The concerns about environmental pollution have gained paramount importance. The internal combustion engines of the vehicles release carbon dioxide and thereby make the air unfit for breathing. The number of vehicle on-road is increasing day by day and the net result is the increased pollution levels. Due to the technological improvements, the modern cars have relatively lower emission levels than their predecessors. In spite of this the pollution problem is of high concern. To overcome the drawbacks associated with the internal combustion engines, more and more stress is being laid towards the development of Electric Vehicles (EV). Traditionally, the development of the EV has been hindered by the non-availability of an appropriate battery. Lead-acid batteries have mostly powered the EVs. These batteries limit the movement of an EV to about 125 km. Further, the cycle life of this battery is very poor. Nickel-iron batteries possess more energy and thereby give better range to the EV. The major drawback here is that the battery has to be watered periodically. Nickel-Metal-Hydride (NiMH) is one of the advanced battery technologies available for commercial applications. This battery has already made inroads into the applications like laptop computers and cellular phones. NiMH batteries have 50 per cent more efficiency than the corresponding lead-acid counterparts. In the NiMH cell, a nickel hydroxide positive electrode is coupled with the metal hydride negative electrode. This cell exhibits high power and a long intrinsic life cycle. The tolerance to electrical abuse is also very high. All NiMH batteries contain positive and negative electrodes, separator, electrolyte, and cell container. Stacking enough positive and negative plates in parallel achieves the desired cell capacity. The results of nickel-metal hydride batteries are highly encouraging. Since its inception in 1993, hundreds of NiMH battery packs have powered electrically propelled vehicles around the world. These include electric cars, trucks, scooters, bicycles and military vehicles. EVs with NiMH battery packs have been successful in sun, rain and snow in the temperature range of -25 degree centigrade to +50 degree centigrade. NiMH technology is still in an infant stage. Designing a practical EV battery is a major task. In addition to high energy and power densities, they must be long-lived, tolerant to electrical fluctuations, possess maintenance-free operation over a wide temperature range and last but not the least they have to be safe. This situation perfectly depicts the “chicken and egg” dilemma. The advanced batteries will be affordable it produced in bulk. This will happen only if the auto majors commit to volume production of electric vehicles. The day is not far when the EVs will ultimately cost less than fuel-powered vehicles. |
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Safer drinking
water Researchers at the Swiss Federal Institute for Environmental Science and Technology, Duebendorf have developed an easy, inexpensive way of making water safer for drinking. According to it, you simply fill clear plastic bottles with water and leave them in the sun for some time. The heat warms up the water and the combination of warm water and ultraviolet radiation kills most of the injurious microorganisms. “SODIS (solar disinfection) efficiently inactivates bacteria and viruses,” explain the researchers. Tests have shown that 99.9 per cent of the Escherichia coli in a sample of contaminated water were killed when sun heated the water beyond 50 degree centigrade for one hour. Painting half the bottle black and laying it on corrugated metal sheet shortens the time taken to warm up the water. People can particularly take recourse to this technique when local water supplies get contaminated from floods. While chlorination tablets are often in short supply, it isn’t difficult for people to get hold of used plastic bottles. Even otherwise, people commonly taking drinking water from exposed tanks, ponds or wells can purify their water with the aid of this technology. With the increasing consumption of bottled drinks among the health-conscious middle classes, plenty of empties are available. The growing urban population of the poor can easily make use of the technique when they have to use water of suspect quality, such as from handpumps. And these plastic bottles going from the rich to the poor reduce the waste in urban areas. Of course there could be a shortage of suitable plastic containers in emergency areas. But once people come to understand the advantages of solar disinfection in this manner, they will manage to get hold of the needed bottles. And may continue to use them thereafter. The very practice of drinking water from a bottle instead of from an open container, if it becomes widespread among masses, will mark a significant advance towards the use of safer drinking water. Both the Swiss agency and oxfam have been promoting SODIS in various countries in Asia, Africa, and South America. Water-related illnesses claim 5 million victims every year over the world. SODIS is particularly good at killing the bacterium that causes cholera. SOIDS also inactivates some other common human parasites such as cryptosporidium that causes severe diarrhoea. It would be an excellent idea to give much publicity and encouragement, both in rural and urban areas, to this rather simple technique of purifying drinking water. Millions of our people are still denied access to safe drinking water. |
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Nucleus in a
looking glass Gloves do it. Toupees do it. Even twists of DNA do it. And now, for the first time, physicists have discovered that atomic nuclei come in right and left handed models too. A team of physicists from the State University of New York, the University of Tennessee, and Notre Dame reports observations of rapidly spinning nuclei morphing into mirror-image forms. In the process the physicists also uncovered solid evidence that a long-disputed feature of nuclear anatomy really does exist. “These results are causing quite a stir among nuclear structure physicists,” says Rod Clark of Lawrence Berkeley National Laboratory in California. Although more work is needed to mail down the conclusions, Clark says, “it is tremendously difficult to come up with an alternative interpretations” of the findings. The discovery springs from work by Stefan Frauendorf, a nuclear physicist at the University of Notre Dame in Indiana. In 1997, Frauendorf and colleagues were exploring the possible properties of atomic nuclei with a hypothetical feature called triaxial symmetry. Theoretically, nuclei can have varying degrees of symmetry, from spherical to ellipsoidal to triaxial, depending on how the neutrous and protons arrange themselves. An ellipsoidal nucleus resembles a football; a triaxial nucleus is similar, but squashed. “It actually looks a bit like a kiwi fruit,” says Krzysztof Starosta, a visiting professor at NY. Frauendorf suggested that certain triaxial nuclei should come in left and right handed varieties. His calculations showed that the development of handedness, which physicists call chiral symmetry breaking, should occur in rapidly rotating “odd-odd” nuclei — those containing both an odd number of neutrons and an odd number of protons. Much as electrons in an atom pair up to form shells surrounding the nucleus, the protons and neutrons in the centre of the atom pair up, like with like, to create their own structures inside the nucleus. In an odd-odd nucleus, however, one neutron and one proton are left over. In some cases, these “valence nucleons” orbit at right angles to each other outside the nuclear core made up of the other protons and neutrons, just as valence electrons whiz around the electronic shells of an atom. According to Frauendorf, those three motions - of the two valence nucleons and the triaxial core-should create a chiral effect. Added together, they give the nucleus its overall momentum. But because the core can spin in either of two directions with respect to the orbiting particles, the overall momentum can take on two different values, too. Those values, Frauendorf said, establish the left-handed and right-handed states. The catch was that nobody knew whether triaxial nuclei really exist. Nuclei with three distinct axes of symmetry had been predicted in the 1960s and hotly debated ever since, but no one had definitely observed one. Some physicists suspected that the triaxial shape might be a fleeting oscillation of the nucleus, too unstable to have a measurable effect. To find out, Starosta and his workers looked at gamma rays, a kind of radiation that atomic nuclei emit after being excited to high-energy spin states. If the nuclei were triaxial and were undergoing chiral symmetry breaking, the gamma rays ought to cluster into pair of closely related frequencies known as doublets — evidence that the energy levels of the nuclei had split into pairs of right and left handed states. The smashups initiated fusion reactions that created excited nuclei of just the right type and pumped them up to the right spin states. As the nuclei settled down, they emitted a panoply of gamma rays with various energies. The telltale clustering was there; by sorting out doublets, the physicists confirmed the existence of chiral symmetry breaking. The next step is to see whether odd-odd nuclei of other elements also form mirror images. Clark says understanding how these complex nuclear structures behave may spill over to other fields as well. “The ideas and methods for understanding nuclei, molecules, metallic clusters, and stomic condensates all feed off of each other.” |
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Communicator for new age This device is going to find a lot of utility in corporate offices. The Cisco IP Phone-7960 delivers essential business communications by providing the most commonly used business features — such as instant updates on stocks, news, weather or any other web-based information which are flashed on a pixel-based LCD display. It also comes with a directory access protocol standard directory that provides user mobility within the office — while retaining the feature of the direct dialling. It identifies incoming calls and categorises them for users on the screen. It allows users to quickly return calls using dial-back facility. The other key services provides provided by this phone are video conferencing, prioritising calls, the name and number of the person called, total calls received with telephone numbers, missed calls and dialed calls. The phone provides many accessibility methods according to user preference. Various methods or paths include buttons, soft keys, a navigation key and direct access with the use of corresponding digits. This easy-to-use phone comes with a direct connection to an Ethernet network with single LAN connectivity and its cost can varies depending on the number of lines required in an office.
Fern as remediator of soils The discovery that a fern can absorb highly toxic and carcinogenic substance, arsenic, from contaminated soils has opened up the possibility for its use for remediation of soils. Scientists in the USA have found that the fern (Pteris vittata), known as brake fern, can absorb arsenic from soils and translocate it to its parts above the ground including leaves (fronds), according to a report in the Science Journal Nature. The report says the plant is most probably the first arsenic hyperaccumulator and the first fern to have been discovered which acts as hyperaccumulator of any substance. The team analysed the fronds of the fern growing at a site in Central Florida which was contaminated with chromated copper arsenate. Simultaneous analysis was also done of other plants growing at that site. According to the report, of the 14 plant species analysed, only brake fern contained large amounts of arsenic with its concentration ranging from 3,280 to 4,980 parts per million (ppm).
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SCIENCE QUIZ 1. This Indian biophysicist, who died recently, was one of the founders of molecular biophysics. He worked in diverse fields such as crystallography and mathematical logic and devised a method of reconstructing a two-dimensional image into a three-dimensional one. Name this man of multiple talents who also translated the Bhagawada Gita in free verse in English. 2. Using microwaves, scientists at the Indian Institute of Science, Bangalore, have recently synthesised a ceramic called GAP. This new method takes less than one hour for the purpose, whereas the conventional furnace method takes 14 hours. What is the complete name of GAP, which is used for a range of high temperature applications, such as turbine engine and rocket engine coatings? 3. We know about genetically inherited diseases, whereby disease cells pass on from parents to their offspring. Scientists have recently discovered some diseases caused by cells from the foetus entering into the mother’s blood stream. What name has been suggested for such a situation? 4. A compound called “liver of sulphur” is used in the treatment of skin diseases. By fusing which two substances is this compound formed? 5. This bird has about 100 times better night vision than ours. Its hearing power is also much better than that of most other birds. Which is this bird whose neck is so flexible that it can rotate it through 270 degrees and see almost all around? 6. When this invention took place, nobody knew how to make use of it, so it was called “an invention in search of a job”. Which was the invention? 7. “An equal number of atoms, combined in the same way, produce the same crystal form which does not depend on the nature of the atoms, but only on their number and mode of combination”. Who discovered this law? 8. In an analogue system, data are represented by continuous variations. How are data represented in a digital system? 9. This is a very accurate and non-destructive means to test the purity of gold. Which is this device that uses X-rays for this purpose? 10. HAREDA is an organisation of Haryana state set up with the purpose of developing non-conventional energy sources in the state. What is the full name of this organisation? Answers 1.
G. N. Ramachandran 2. Gadolinium aluminium perovskite 3. Reverse inheritance 4. Sulphur and potassium carbonate 5. Owl 6. The laser 7. German chemist Eilhardt Mitscherlich 8. By discrete numbers, such as 1s and 0s in a binary system 9. Karatmeter 10. Haryana Renewable Energy Development Agency.
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