 |
|
| SCIENCE TRIBUNE | Thursday, October 19, 2000, Chandigarh, India |
|
Health hazards from pollution Biodegradable arterial
stents Science Quiz |
|
|
Towards developing microsatellites THE increasing cost of delivering a satellite payload into space has been a major factor behind the costly pricetag of a satellite mission. By decreasing the launch cost, a satellite mission can be turned into an affordable preposition. To this end, researchers at the Ohio based aerospace company TRW are involved in developing what is called as “microscopic rockets”. In the none too distant a future these microscopic rockets could pave the way for the evolution of “microsatellites”, which will ultimately replace today’s expensive commercial communications satellites. Many of these weigh just around 3 kg. According to TRW researchers, these microsatellites offer a cost effective means of communications in any part of the
world. The TRW researchers, in a radical departure from conventional satellite engineering, are busy devising simple rockets with no moving parts by carving components out of silicon wafers. Initial tests have shown that this technology is astoundingly simple. To begin with, the researchers take silicon wafers protected on both sides by a 500 nanometre thick layer of silicon nitride which is impervious to the etching chemicals used in producing microchips. Thereafter, they mark out the components they require using a programmable laser to burn off the silicon nitride layer in areas they want to etch out. Finally, they immerse the chips in potassium hydroxide to eat away exposed silicon, leaving the other materials
intact. The rockets so developed are known to operate under the principle of “digital propulsion”. The advantage is that these thrusters can be fired singly or in groups to produce the required amount of thrust. These thrusters containing only a few tiny grains of fuel. They enjoy a specific advantage when it comes to manoeuvring microsatellites. Engineers describe the shortest burst that a rocket produces as an “impulse
bit”. All said and done, squeezing hundreds of thrusters into a small space carries its own risk. For as each thruster fires, the exhaust gases inside reach more than 1500 degrees celsius. These hot gases are separated from the propellant in neighbouring thrusters by walls just fractions of a millimetre thick. If the heat reaches this propellant, a whole array could go up like a string of
firecrackers. Fortunately, there is a way out of the problem. By making sure that the propellant burns fast, one can ensure the flawless functional efficiency of the thrusters. Clearly and apparently, if the reaction is quick enough, the surrounding walls simply don’t have time to heat up. The researchers are already using lead styphnate, a powerful compound which burns up so rapidly that there is no time for heat to transfer to other
chambers. Space technologists feel that if these “miniature rockets” could be mass produced they could definitely revolutionise the way military planners and scientists use satellites in the years ahead. For instance, a swarm of microsatellites could be used to pick off ballistic
missiles. Beyond the space applications, these micro satellites could be used to create tiny robots. |
|
Health hazards from pollution TODAY, the world is facing a serious challenge to save its environment from pollution, as the very survival of life on this planet is threatened. Many animal species in India have become extinct. The National Institute of Oceanography has reported that shrimp, prawn and fish yield off Kerala coast has declined by 25 per cent due to coastal pollution. A Washington-based World Watch Institute had earlier warned that there is a beginning of an unprecedented biological collapse worldwide because three-fourths of the world’s bird species are threatened with
extinction. The Supreme Court had taken a serious view of the alarming air pollution in Delhi. It had directed the government to upgrade fuel quality and to run vehicles with compressed natural gas (CNG) kits. It has also ruled that any person found polluting the environment and disturbing the ecological balance is liable to pay damages.
Pollutants have been adversely affecting the atmosphere and the climate and thereby, affecting the human society. High inputs in agriculture such as chemical fertilisers, pesticides have been creating a variety of pollution problems, affecting the development of flora, and fauna, accumulating harmful chemical substances in food having deleterious effects when consumed. Some of them are cancer-causing or carcinogens, and thereby posing a great risk to the health of the
people. The use of excessive nitrogenous fertilisers has increased concentration of nitrates in the river waters. As a result, their concentration in the drinking water has increased. These nitrates in high concentration are toxic and promote stomach cancer. The continuous use of pesticides has affected the ground water sources through seepage into the soil. As a result, rivers, streams and ponds have become polluted with these harmful chemicals affecting the drinking water. Some of these pesticides have been characterised as carcinogens. Their accumulation in different foods is hazardous to human health. The level of accumulated DDT in the body tissue of an average Indian is the highest in the
world. The use of petroleum as a fuel in over 630 million automobiles in the world has been a cause of large-scale pollution. Over 15 million tonnes of carbon monoxide, one million tonnes of nitrogen oxides and 1.5 million tonnes of hydrocarbons are added to the environment every year. The amount of carbon dioxide introduced into the atmosphere due to the burning of
fossil fuels, comes to billions of tonnes per year. The developed countries account for 70 per cent of the atmospheric pollution in the
world. In India, which is a relatively underdeveloped country, the pollutants in the form of sulphur dioxide, particulate matter, carbon monoxide, nitrogen oxides, lead oxide and hydrocarbons belched out into the atmosphere amounts to a few million tonnes per year. Delhi is ranked fourth among the 41 cities of the world monitored for air pollution caused mainly by automobiles numbering over 30
lakh. These pollutants have been causing global changes. The nitrogen oxide and sulphur dioxide gases are responsible for acid rains in the various parts of the globe. These together with the hydrocarbons in the presence of sunlight, lead to the depletion of the ozone layer. Carbon dioxide gas is one of the main contributors of the greenhouse effect, which is slowly raising the temperature of the world. Fourteen per cent of the carbon dioxide comes from the
fossil fuels. These pollutants cause of number of diseases like lung cancer, asthma, bronchitis, tuberculosis, etc. In the affluent residential areas of Bombay, a large number of people have been suffering from bronchitis, asthma and lung cancer. Delhi is at the top in the country in respect of lung diseases with 30 per cent of its population suffering from respiratory diseases. In Delhi, people have a 12 times higher chances of respiratory and throat diseases because of pollution by poisonous gases. 80 per cent of cancer is attributed to environment polluted with toxic and hazardous chemicals. Smoke from petrol, diesel, coal, wood, charcoal, cowdung and cigarettes is
carcinogenic. Lead pollution from industry and automobiles has been on the increase posing a serious environmental hazard. Automobile & diesel engine exhausts contain lead which is a carcinogenic. Lead from automobile exhausts accumulates in the form of dust. 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. 50 per cent of the Bombay City’s population contains 30 microgram of lead in 100 ml of blood; while 50 microgram is enough to cause brain
damage. The Gulf War created the world’s worst ecological disaster. Such a large-scale ecological and human tragedy was almost equal to the combined disasters of Hiroshima, Bhopal and the Chernobyl. Burning of Kuwait oil wells, petroleum refineries and oil slick polluted the vast areas surrounding Kuwait with suspended particulate matter, poisonous gases and other toxic substances. Iraq became a “poisoned desert” as many of its parts were contaminated with highly toxic chemicals causing epidemics. Cholera & diarrhoea diseases were widespread because of polluted drinking water. Hundreds of children
died. Petroleum and industrial hazardous wastes have increasingly polluted oceans adversely affecting the sea life. As a result, fish became contaminated with poisonous matter. Consumption of these fish caused diseases of the spinal cord. Oysters (shellfish) from water polluted with petroleum wastes are found to contain potential carcinogens. Consumption of contaminated seafoods by humans causes numbness, giddiness, incoherence of speech and gastro-intestinal disturbances. In extreme cases, it may lead to death due to paralysis of the respiratory
muscles. Combating pollution has been receiving worldwide attention. The world bodies have proposed to imposed taxes and levies on the industrial units causing pollution. The Supreme Court has issued directions to take suitable action against those polluting the environment and disturbing the ecological balance. If such a large-scale pollution is not checked, it would be difficult to achieve the goal of health for all. |
|
Biodegradable arterial stents A biodegradable arterial stent, a tube that is inserted into clogged blood vessels to restore proper blood flow, has been successfully tested in humans for the first time in
Japan. The new stents could revolutionise coronary angioplasty, a procedure to reopen narrowed blood vessels, says lead researcher Hideo Tamai of the department of cardiology at Shiga Medical Centre,
Japan. A traditional stent is a tube — usually a cage of surgical-grade stainless steel somewhat resembling chicken wire — that props open an artery that has become partially closed from the fatty build-up of atherosclerosis. A multi-centre randomized U.S. study of biodegradable stents is now being planned as a follow-up to the Japanese research, according to a report in Circulation, a journal of the American Heart
Association. “If this study supports our findings about the efficacy of biodegradable stents, and if the FDA approves them, these could be in general use in America within a few years, “Tamai says. |
|
Science Quiz 1. This British surgeon discovered the use of antiseptics in 1865 and brought down drastically the post-operative mortality rate by using an antiseptic agent along with the method of heat sterilisation of instruments. Name the surgeon and the first antiseptic chemical used by him. 2. This disease, commonly known as rat fever, because it is spread by rats, took alarming proportions recently in Kerala and claimed dozens of lives. Its main symptoms are high fever, redness in eyes, shivering and joint pains. What is the scientific name of this disease, for the treatment of which at least 10 antibiotics are effective? 3. Hargreaves — Bird cell is an arrangement designed for the preparation of sodium hydroxide (and chlorine) by the electrolysis of brine. Which is the improved form of this cell that keeps the chlorine away from the alkali by means of a diaphragm and thus can be used for the manufacture of sodium hydroxide only? 4. Suppose we are doubtful about the purity of a piece of gold. Can you suggest three main methods to estimate its purity? 5. TCE is an ingredient in inks, paints, lacquers, varnishes and adhesives, and is also used in dry-cleaning. What is TCE chemically, which has been found to be a potent liver carcinogen? 6. The egg-shaped brown fruit of sour-sweet taste, low in calories but more nutritive and fibrous than other fruits, originally grew wild in China. This Chinese gooseberry, now grown in many countries (not in India), has been named after a flightless bird of New Zealand. Which is this only fruit in the world having bright green flesh? 7. An algae as a source of fuel? Scientists have recently found a microscopic plant algae which uses the energy of the sun to split up water into its components and thus produces hydrogen gas, which can be used as a fuel. Can you name this algae? 8. LIDAR is a device used for the detection, observation and study of distant cloud patterns employing laser beams. What does LIDAR stand for? 9. We know that a binary star consists of two stars, each revolving around a common point. These stars have been divided into three classes, depending upto their methods of detection. Which are these three classes? 10. This spacecraft, planned to be launched by the US space agency NASA towards the sun in January, 2001 and expected to complete its mission in two years, will collect definite evidence for the origin of sun’s atmosphere. Can you name this spacecraft which will also study the effect of magnetic storms on earth? Answers 1. Ist Baron Joseph Lister; carbolic acid (phenol) 2. Leptospirosis, also called Weil’s disease 3. Nelson cell 4. Spectrography, chemical analysis and measurement of its density 5. Trichloroethylene 6. Kiwifruit 7. Chiamydomonas reinhardtil 8. Light Detection And Ranging. 9. Visual, spectroscopic and eclipsing binary stars 10. Genesis.
|
|
New products & discoveries Multi-layered parking THE latest development in space saving is this incredible new parking system for cars and buses. Seen at the Eiraku Tourists Bus Depot in Tokyo, the parking unit is said to be a major space saver and does away with the harassment caused to drivers looking for parking space in the over-crowded
city. The parking lot has three levels. It is eight metres high by 25 metres wide and 12 metres deep. Built at a cost of Yen 280 million, it can house 50 cars and 25 13-ton
buses. Parking space is so scarce in Tokyo that the compact unit is considered a most welcome invention and the government is vigorously working out plans to have similar parking lots in other crowded city centres as
well. Antarctic ozone depletion THE hole in the ozone layer is now three times larger than the USA — its biggest size ever, scientists at NASA said. United Nations (U.N.) weather experts said the hole over the Antarctic is growing earlier in the year than
usual. Measurements of ozone depletion vary from year to year, making it difficult for scientists to determine the long-term environmental impact of changes in the ozone layer. Still, this year’s hole-large and early-caught atmospheric experts
off-guard. “The fact that it’s real big right now is kind of a surprise,” said Dr Paul A. Newman of NASA’s Goddard Space Flight Centre in Greenbelt,
Maryland. The centre detected an ozone hole of about 28.3 million square kilometres on September 3. That was the biggest ever, beating the previous record of 27.2 million square kilometres on September 19, 1998, it
said. Elusive tau neutrino Scientists
have found the first direct evidence of the tau neutrino, an elusive and ghostly sub-atomic particle that was thought to be the last missing piece in the architecture of matter.
The breakthrough was achieved by scientists at the Fermi National Accelerator Laboratory outside
Chicago. “It’s a tremendous milestone,” said Stanford University physicist and Nobel Prize winner Martin Perl, who first theorised the existence of the tau neutrino in 1978. “Now it has been seen and it behaves in the way we expected,” Fiftyfour scientists from the United States, Japan, Korea and Greece had collaborated on tracking down the tau neutrino since 1997 at the Fermi
Lab. The tau is one of the fundamental building blocks of all matter. It is the 12th and last of the impossibly tiny particles described in the Standard Model of particle physics to be confirmed in experiments. The Standard Model seeks to encapsulate all elementary particles and forces in a single explanation. Now the bits have been identified, though the many forces that guide their interplay remain a
mystery. “We finally have direct evidence that the tau neutrino is one of the building blocks of nature,” said Byron Lundberg, spokesman for the international team. “It is one thing to think there are tau neutrinos out there. But it is a hard experiment to
do.” A small structure in the front of the brain may be a master problem solver, according to a study that found it works the hardest when the mind is confronted with intelligence
tests. The study, published in the journal Science, measured blood flow rates in the brains of test subjects who were required to answer a series of puzzles typical of those in IQ
tests. John Duncan of the Medical Research Council in Cambridge, England, and co-authors report that the most active region of the brain during the tests was the lateral prefrontal cortex, a structure in the forebrain just above the eyes. This structure is present in both the left and right hemispheres of the
brain. The brain activity was measured using positron emission tomograpy, an imaging technique that pinpoints areas with the highest level of activity by measuring the rate of blood flow. A higher blood flow suggests more intensive
activity. When 60 test subjects connected to the scan were asked to perform a series of verbal and spatial puzzles, like those found in IQ tests, the lateral prefrontal cortex was the area that experienced the most blood flow. |
|
IN the article “Solar (PV) Pumps — Common Pitfalls” by Mr G.S. Dhillon, the information given by the writer in the first paragraph is wrong and misleading. No doubt the Punjab Government has decided to install 500 solar photovoltaic water pumps systems for meeting irrigation needs of the farmers during the current financial year. This scheme is being implemented through the Punjab Energy Development Agency (PEDA), which is a state nodal agency for promotion and development of non-conventional energy sources in the state. It was decided earlier to implement this scheme in the selected 12 blocks of the state. Now, on strong demand from the farmers, this scheme is being extended to 35 blocks. The capacity of this solar pump will be 2HP (1800 watts) instead of 5 HP wrongly depicted in the
article. The estimated cost of one such solar pump is Rs 4.56 lakh, including maintenance charges for five years. These pumps will be supplied to the farmers at the cost of Rs 35,000 instead of Rs 50,000 mentioned in the article under the lease arrangement after availing financial incentives from the Ministry of Non-conventional Energy Sources (MNES), Govt. of India, Indian Renewable Energy Development Agency (IREDA) and the state
government. The state government contribution to the scheme will be limited to Rs 3 crore only against the total project cost of Rs 22.80 crore. The provision for state contribution has already been made in the state budget in the current financial year. An elaborate advertisement for inviting applications from the farmers has already been released through your newspaper and as also other newspapers twice during the last
month. S.S. Sekhon Director, PEDA. An omission Inadvertently, there has been an omission in the statement of question no. 2 in
Science Quiz published on September 28, 2000. The question may be read as
follows:- If we take the square of the charge of an electron and then divide it by the speed of light times Planck’s constant bar/cut, we get a pure number. what is the name of this number? What is its
value? Thanks to Dr Dinesh Pal Singh of Adampur (Hissar) for pointing out the
omission. J.P. GARG |
 |
|
