 |
|
| SCIENCE TRIBUNE | Thursday, July 19, 2001, Chandigarh, India |
|
Oceans
of water beyond our solar system? Advantages
of Ready Mix Concrete Power
from thin foils NEW PRODUCTS &
DISCOVERIES
SCIENCE QUIZ
|
|
|
Oceans of water beyond our solar system? SINCE time immemorial, human beings have gazed towards the sky and wondered: Are we alone here? They had no way to confirm or deny that that they had neighbours living anywhere beyond the earth, unless one went by myths and fables. The only theoretical reassurance that they had was that Nature could not have wasted so much of space only for the viewing pleasure of mankind. Even after instruments were developed that could have a close look at the neighbouring planets, it was frustrating to find that most of them were bone dry and hardly in a position to sustain life as we knew it. Even moon, the neighbour next door — in astronomical terms, that is -- was no place for life to flourish. The hypothesis that it might have water in its craters could not be sustained for want of adequate proof. Water, as we all know, is an essential ingredient for known forms of life. Other planets were found to be even less hospitable. To optimists' delight, planets were discovered beyond our solar system. Over the past decade, more than 60 stars have been found to have planets. But little is known about the composition of those planets. As telescopes grow more sophisticated, this number is bound to multiply. But the big question remains: is there life out there? Most of those systems which harbour very large planets close to the central star, don't seem to be much like our own solar system. New hope has arisen in this regard with a startling revelation last week. Recent observations by the Submillimeter Wave Astronomy Satellite (SWAS), a NASA small explorer project designed to study the chemical composition of interstellar gas clouds, has indicated that there may be worlds outside our solar system that have oceans of water like the earth. Recent observations with SWAS found significant detections of light at specific colours emitted by water for scientists to conclude that nearby star system CW Leonis harbours water. It is the first evidence that extra-solar planetary systems contain water. CW Leonis, also known as IRC+10216, is an aging giant star located about 500 light years away towards the constellation of Leo. The hypothesis is that the activity of the central star is vaporising water from a cloud of comets that surround the star. The cloud may be similar to the Kuiper Belt of comets that surround our own sun beyond the orbit of Neptune. There must be about four earth-masses of frozen water around the star. The observations of water vapour around IRC+10216 suggest that other stars may be surrounded by planetary systems similar to our own. What is all the more exciting is that not one or two but several hundred billions of comets are vaporising at the same time! These comets are between 75 and 300 times the distance of the earth from the sun. The number may appear to be extremely large but the total mass required is similar to the original mass of the Kuiper Belt. It has been explained that in our own solar system, when a comet occasionally comes close to the sun, it starts to vaporise and displays the characteristic coma and tail that we are familiar with. But IRC+10216 is so much more luminous than the sun that the comets start vaporising even at the distance of the Kuiper Belt. CW Leonis was once a well-behaved main-sequence star, just as our sun is now. It was then between 1.5 and 4 times the mass of our sun and so evolved more quickly. About one billion years ago, it exhausted the nuclear fuel at its core. This alien sun in its death throes is now burning the remaining hydrogen and helium in thick shells surrounding a core enriched in carbon. In this phase of its evolution, its radius has increased nearly a thousand times and its luminosity also has increased by a factor of between 100 and 3000. That is why it is evaporating comets - "dirty snowballs" that are composed primarily of water ice -- lying so far away. If it were located at the centre of our solar system, say astronomers, it would engulf Mercury, Venus, earth, Mars and Jupiter. Ironically, the apocalypse that we are now witnessing from a safe distance of 3,000 trillion miles will befall our own planetary system a few billion years from now. According to SWAS team member Devid Neufeld, Professor of Physics and Astronomy at Johns Hopkins, the sun will become a giant star and its power output will increase five thousand fold. As its luminosity increases, a wave of water vaporisation will spread outwards towards the solar system, starting with earth's oceans and extending well beyond the orbit of Neptune. Icy bodies as large as Pluto will be mostly vaporised, leaving a cinder of hot rock. SWAS, a small radio observatory, was launched by NASA into low earth orbit on December 9, 1998, primarily to survey water, molecular oxygen, carbon and isotopic carbon monoxide in a variety of galactic star-forming regions. From its vantage point in orbit above the absorbing effects of water in the earth's atmosphere, SWAS is capable of detecting the distinctive radiation emitted by water vapour in space. Its science operations centre is located at the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts. Over the past two years, it has detected water vapour from a wide variety of astronomical sources. But what makes the current results so unusual is that water vapours have been found around a carbon-rich star which was not expected to contain significant amounts of water at all. "Although it is a pretty hot place, there could be cooler worlds circling that star on which liquid water may exist, and if that is the case there may be life," says Dr Gary Melnick of Harvard University. |
|
Advantages of Ready Mix Concrete READY Mix Concrete (RMC) may be defined as concrete manufactured as per specifications of the customer, at a centrally located batching plant and delivered to the construction site in truck mixers capable of mixing the ingredients of the concrete enroute or just before delivery of the batch. The other option available is to mix the concrete at the batching plant and deliver the mixed concrete to the site in an agitator truck which keeps the mixed concrete in correct form. The delivery trucks have capacities of 6 m3 to 7.5 m3. In the case of the centrally mixed type, the drum carrying the concrete revolves slowly so as to prevent the mixed concrete from “segregation” and prevent its stiffening due to initial set. However, in the case of the truck-mixed concrete, the batched material (sand, gravel and cement) are carried and water is added just at the time of mixing. In this case the cement remains in contact with the wet or moist material and this phase cannot exceed the permissible period which is normally 90 minutes but can be extended in the case of longer haul by addition of a ‘retarding admixture}. The materials to be used for making RMC should conform to the requirements of IS 456:2000 or relevant code.
Mix Proportions The greatest advantage of RMC is that concrete conforming to the specification or mix proportion of the customer can be supplied. But under the clause 9.2 or IS 456: 2000, the RMC manufacturer has to guarantee the quality of concrete as he shall be responsible to carry out the mix design which may be got approved the purchaser. These provisions sometimes lead to conflict. Though the RMC contractor is at liberty to use any method of mix design he is, however, required to get the approval of the purchaser for the mix design being adopted. “Special concretes” can also be made available by RMC producer to meet the demand of small and medium sized projects. One can order “fiber-reinforced concrete”, “coloured concrete” or concrete administered with flyash, slag or microsilica. The use of such admixtures result in durable concrete. For example addition of flyash results in improved gel of the concrete and the resulting pozzolanic action gives upon hardening “dense and less permeable concrete which has got greater resistance towards weathering agents,” and hence there is greater durability of structures built with flyash concrete. RMC is particularly useful when the building activity is located in congested sites where little space is available for siting the mixer and for stock piling of aggregates. In the case of the site mixed concrete, control over the concrete production is a little difficult and there is complete absence of control over the aggregate: cement ratio and the cement: water ratio. In addition, no control is exercised over the grading of the aggregates. The concrete obtained though may satisfy the builder, but if tested will fail to come upto the standard or required grab of strength. The use of RMC is also advantageous when only small quantities of concrete are required or when concrete is to be placed only at intervals. The teething troubles has been overcome by the RMC Industry and at present there are over 37 RMC plants delivering over one lakh cubic metres of mixed concrete every month. RMC plants are working in Delhi area also. Recent experience of Gujarat earthquake (Jan, 2001) has shown that failure of most buildings which led to loss of human life, were due to loss of bond between the concrete and steel reinforcement on account of poor quality concrete having been used. In the sound concrete made with strict control over water: cement ratio and thoroughly compacted, such failures do not occur. So, to obtain a earthquake resistant building the use of MRC must be made essential and at the same its availability to the common builder assured in the earthquake prone areas i.e. Zone IV and Zone V areas. Advantages of using RMC include the quality assurance of the material placed and reducing the loss and wastage of materials which is fairly common in the site-mixed concrete. This conservation of materials is another eco-friendly act of RMC. Use of RMC will also impart a social advantage as it would result in improvement of living standard of gangs of workers involved in operations related to the site mixed concrete placement. The speed of construction can be controlled and increased which will result in the cost benefit as it would be possible to put the structure in the use earlier as compared to that which would have been possible if site mix procedure had been employed. RMC use would also help avoid the accidents of vehicles which occur on account of skidding over spilled of left-over sand and gravel on the road and berms where site mixing procedure has adopted. |
|
Power from thin foils THE trend in battery development is moving inexorably in the direction of smaller, lighter units which are more powerful, reliable and flexible. The requirements are extremely diverse, depending on whether they are to be used in a notebook computer, mobile phone, heart pacemaker or chip card. The power required varies from a few milliwatts to 100 watts, operating lifetime from a few hours, or up to years. The key requirements for this are energy-saving electronics and an integrated energy supply. This requires interdisciplinary cooperation in the fields of semiconductor and component technology, electrochemistry, solid-state ion research physics, polymer research, and assembly and interconnection technology. Developments in smart cards alone entail a great market potential because soon 20 per cent of chip cards will run on batteries. Different accumulator types already exist: Nickel-cadmium, nickel-metal-hydride (NiMH), alkaline manganese cells and lithium systems offer a broad spectrum of performance, quality and price. To date, they have not been able to overcome their disadvantages — too heavy, too big, too expensive, inadequate service life. World-wide, lithium accumulators are regarded as the most promising device for supplying energy to the next generation of portable information and communication systems, because they possess the highest energy densities of all the rechargeable battery types. First time in the world, the Fraunhofer Institute for Silicon Technology, Germany, has succeeded in proving that high-performance solid electrolyte foil accumulators can be produced which are light in weight, environmentally friendly and inexpensive. The basis for each individual foil layer is a paste which is produced from a powder mixture of polymer electrode or electrolyte material and solvent. The cell is only 0.5 to 1 millimetre thick and adaptable in surface area. The flexible cells can be shaped as required, rolled, stacked to form flat, cuboid or cylindrical packages. The development of mini and micro fuel for portable electronic devices in the extremely low power range is still in its infancy. Fuel cells typically produce electricity through the reaction of hydrogen with oxygen. One design of a mini fuel cell is based on a strip membrane concept developed by the Fraunhofer Institute for Solar Energy Systems which permits a very flat design. For applications with low output voltages they developed a highly efficient DC/DC transformer which functions with input voltages as low as 0.55 V. The combination of the fuel cell with a direct current transformer enables the voltage to be adapted to various electronic consumers. The prototype, which has a diameter of just 144 mm, a height of 20 mm and weighs 500 grams meets these requirements. Thin foil accumulators can deliver energy up to 50 watts, enough to power small devices, including laptops and camcorders. Such micro fuel cells are intended to one day provide the power supply for palmtops, hand held electronic games and other small devices. |
|
NEW PRODUCTS & DISCOVERIES A new technology for the treatment of water from human waste has been successfully developed by researchers and they hope that this would help tackle the water shortage problem in drought prone areas. This charcoal Ultra Violet filter of water, developed by researchers in Sulabh International Institute of Technical Research and Training, treats waste water from human excreta based biogas plant. The treated water is colourless, odourless and pathogen free. Its BOD (Biological Oxygen Demand) is less than 10 mg per litre which is quite safe for fish culture, irrigation and horticulture. “It can also be used for cleaning the floor and maintenance of Sulabh Complex, particularly in drought prone areas in Rajasthan and Madhya Pradesh, where water is being purchased to maintain the toilet complex,” Dr P K Jha, Vice-Chairman and technical adviser of the organisation told PTI. The water can be made potable with only a slight technological input, he said. “In addition to nitrogen, potassium and phosphate this water contains all plant, micronutrients required for the growth of plant, Jha said adding that the water has advantages of inorganic fertilizer in many ways as it improves soil texture and does not cause acidity or alkalinity of the soil besides improving the growth of microorganisms in the soil.
PTI Novel heating system Researchers have developed a highly innovative and compact domestic energy system that makes an enormous contribution to reductions in emissions of carbon dioxide — one third of which is attributed to heating of buildings. “Passive” solar houses cover a large part of their energy requirements with the solar power they capture, the rest is provided by the technical system developed by the Fraunhofer Institute for Solar Energy Systems ISE in collaboration with several industrial partners. Passive solar houses are built in such a way that as little heat as possible is lost through walls and windows. In addition to the thermal insulation incorporated in the construction of the house, this also calls for controlled ventilation of the building. The use of solar energy alone suffices to reduce the annual requirement of heating energy — in the temperate climate of central Europe — from an average of ten litres of oil per square meter to the equivalent of one litre. In order to generate the remaining requirement, the company Maico Haustechnik Systeme offers a new and compact ventilation device, a report in Fraunhofer Gesellschaft. Dr Christel Russ of ISE explains how it works: “The system recovers heat from the exhaust air in combination with a heat pump. In this way it provides an intake of fresh, warm air and — as a backup to the solar collectors — serves to heat household water. There is no need for other forms of space heating, such as hot-water radiators.” Heat is distributed throughout the buildings together with the fresh air brought in by the ventilation system. An agreeable temperature is attained in three stages.
PTI Put the world on
your shoulders FRAMEPACKS, those backpacks with a built-in skeleton that allow you to carry a lot more weight, cost a small fortune — and they’re too unwieldy to drag around, say, Paris for a week. But Swiss Army’s E-Motion backpack offers the best of both worlds. It supports the stuff you’re carrying with a single spine that’s contoured like your back. But for comfort, it pivots from the base of the backpack. The support also turns into a handle, allowing you to wheel the backpack behind you. A handy daypack snaps off for short trips. Available this spring for $325. Popular Science Trees store less carbon Experiments conducted in a North Carolina pine forest show that after an initial growth spurt, trees grow more slowly and do not absorb as much excess carbon from the atmosphere as expected, reports Associated Press. The results suggest that planting trees may not thwart global warming or serve as an adequate substitute for reducing heat-trapping greenhouse gas emissions. Forests typically grow in poor soils. Researchers said that once forests have initially capitalised on the extra carbon in the atmosphere, they quickly deplete nutrients in the soil. Their growth slows dramatically and their ability to store excess carbon is curtailed. “The impact of existing forests on carbon in the atmosphere may not last very long and it might not be very significant,” said Duke University ecologist Ram Oren, the lead researcher in one of the studies. “The forests’ impact on carbon dioxide may not materialise in any important way,” he said. Scientists who did not participate in the studies said results are “potentially very important” in determining the role forests play in regulating the changing climate.
PTI |
 |
SCIENCE
QUIZ 1. This German scientist postulated for the first time that specific organisms have to be present in every case of a particular disease and when introduced into a healthy person the organism produces the same disease. Name this winner of the 1905 Nobel Prize for Physiology or Medicine who, using simple equipment, discovered the bacteria that cause anthrax, cholera and tuberculosis. 2. Scientists at the Indian Institute of Science, Bangalore, have recently developed a small, inexpensive, mobile and palmtop like computer using which even illiterate farmers can learn applications like voicemail and surfing the Net. What has this device been named? 3. What are the devices called that have biological components such as proteins and are generally used to measure environmental pollution or for pre-warning about the onset of certain disease? 4. The Copernican model of the solar system proposed by the Danish astronomer Nicolaus Copernicus in 1543, was a revolutionary concept about the structure of our solar system. By what other name is this model known? 5. Some people eat too less carbohydrates to reduce their weight. But it has been found that in case we continue to eat less than 100 gm of carbohydrates a day for a long time, our body enters a state that causes the body to produce ketones resulting in bad breath. The process may also result in loss of essential minerals like calcium and the body may suffer from harmful metabolic changes. What is such a state of the body called? 6. Which compound is administered to a patient while taking an X-ray of the stomach and intestines and why? 7. Although, absolutely speaking, we have not been able to attain this temperature, all molecular motion is supposed to cease at this temperature, resulting in complete loss of energy by the molecules. What is this temperature? 8. What is common between “Painted Lady”, “Red Admiral” and “Monarch”? 9. Jamun is a very useful tree as its bark, leaves, fruit and seeds all have medicinal properties. Its bark is a very good astringent and can control diarrhoea and dysentery. Jamun fruit is helpful in diabetes, can prevent excessive urination or sweating, is a blood-purifier, digestive, coolant and liver stimulant. It contains certain alkaloids, carbohydrates, minerals and vitamins, besides two acids. Can you name these two acids? 10. The world’s first self-contained artificial heart, free of wires connecting it to an outside energy source, was implanted recently by two doctors. Which was the world’s first ever artificial heart, implanted in 1982, which worked with the help of cables, tubes and an air compressor?
Answers 1. Robert Koch 2. Simputer 3. Biosensors 4. Heliocentric model 5. Ketosis 6. Barium sulphate (also called “barium meal”); because barium, atoms are opaque to X-rays 7. Absolute zero 8. These are varieties of butterflies 9. Oxalic and tannic acids 10. Jarvik-7. |
