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| SCIENCE TRIBUNE | Thursday, May 9, 2002, Chandigarh, India |
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Can
teleporting be a possibility? Cheaper
flat-panel display NEW PRODUCTS &
DISCOVERIES
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Novel
wood substitutes Wood is an important building material and there is an ever growing demand for it by the construction industry. To meet the demand for wood or timber, the deforestation rate has increased resulting in adverse effect on environment. To counteract the adverse impact, the Ministry of Urban Affairs and Employment, in April, 1993, imposed a ban on use of wood or timber in the building construction. Hence the need was felt for finding suitable substitutes for wood. Now boards made from waste products like saw-dust, jute sticks, jute fibre, glass reinforced gypsum matrix and fly-ash polymer composites are available for use as door shutters/panels at a reasonable price. Sisal fibre corrugated sheet for roofing is available for substituting the banned asbestos cement material, as the use of asbestos resulted in health hazards due to carcinogenic nature of asbestos. Glass reinforced gypsum binder composites: This developed product can be used as a substitute for timber in door shutters, structural partitions, false ceilings etc. By varying the quantity of glass fibre in plaster and by controlling other fabricating measures, parameters like modulus of rupture and impact strength of the product can be increased. Improved physical and mechanical properties of gypsum composite render the product comparable with timber polyboards, particle boards. At least four plants are currently fabricating this product in Haryana, West Bengal, Delhi and Rajasthan. Such products have given good performance while put in service for over 10 to 12 years. These boards are fabricated by spray-suction technique and can made to sizes meeting market requirements. Expanded polystyrene composites (EPC) door shutters are being fabricated in two sizes: 2050 mm x 900 mm x 37 mm and 2050 mm x 1050 mm x 37 mm, comprising expanded polystyrene as the core sandwiched between medium density boards with polystyrene modified cashew-nut shells liquid or polyurethane resin as binder. The product has low water absorption value (6-7 per cent) and having density nearly half of that of timber door shutters. Phospho-gypsum door shutters of size 2000 mm x 900 mm x 30 mm, are being fabricated using phospho-gypsum (an industrial waste) as binder and fibres of glass or sisal put in an appropriate frames (of aluminium or steel). For improving workability and surface finish, small volume of fly-ash is added. IWPC (Industrial Wastes Polymer Composites) Technology using fly-ash, red-mud (waste obtained during aluminum manufacture), marble slurry to the tune of 50% of the total volume of raw materials used have given viable products which can act as substitute for wood. Boards so made can be used inside the dwelling units for purposes like partition walls, false ceiling, table tops/mats, as insulation material in place of timber or wooden products. The boards are made using suitable adhesive or cement. Saw-dust (particle) boards have been in use for quite sometime and present several advantages, such as not being prone to insect attack, slower rate of degeneration and ageing compared to polyboards in which different layers or laminations are held by adhesive and liable to fail when exposed to humid environment. Since plywood/blocks boards are made of strips of wood of various species of timber which shrink and expand at different rates when absorbing moisture, they develop a wavy surface with time. Urea-formaldehyde bonded particle boards are less costly than those made with binder of phenol-formaldehyde, but the latter product gives better characteristics i.e. better strength, resistance to bacteria/fungus/moulds and withstand adverse weather conditions better. These particle boards are broadly divided into three groups depending on their density. The low density particle boards are prepared using agro-wastes like rice straw, paddy husk, jute sticks, jute fibre, marble dust etc. and the product fall under requirements of IS 3097-1995. Medium density particle boards are usually made from chips of wood which are bonded together with organic binder or glue depending upon the end use to the board is to be put. Material is produced mechanically to form an aggregate which is used to produce the board and the aggregate may be in the form of flakes, granules, shavings, splinters etc. of wood. Jute stick boards are the structural boards suitable for partition walls, paneling, false ceiling, doors and windows, furniture, shutters, insulation and display boards. These boards possess high (above 20 kg/cm2) and do not sag even for span of 4 ft x 2 ft after a passage of several years. So the doors shutters do not require frame-work. Moreover, the lamina of jute stick boards are available in wide range of colours and do not require further painting and finishing. Plastic coated dust-proof boards have been found suitable for use in the lower reaches of cinema-hall walls and auditoriums. In the case of cloth-faced boards, the edges are neatly covered using extra cloth folded at the back of the boards for the purpose. The boards can be fixed on walls, ceilings using hidden clamps and screws, thus keeping decorative face undisturbed. The boards can be cut, grooved, bevelled, nailed and screwed using the conventional wood-working machines. Jute fibre-boards have been found to be highly suitable for acoustic treatment of auditoriums. cinema halls and offices. For false ceiling of span of 2 ft x 2 ft and for walls span of 3 ft x 4 ft. An extremely novel and economical method of using jute boards or matrix for acoustic/insulation treatment of ceiling is to place these over the wood shuttering during ceiling of a roof and when the shuttering is removed, the board or matrix remains laminated on the ceiling with no extra adhesive or framework. Such a technique was adopted in the case of International Indoor Stadium, Kolkata. This technique eliminated the use of conventional insulation boards. The jute fibre boards have got high insulation properties and are ideal for roof insulation of a completely air-conditioned building. Polystyrene faced boards are normally used for the purpose, but such boards have been found to collapse after a brief service and lose their insulation properties. But the jute fibre boards do not deteriorate under similar conditions. These boards can be cut clean with a sharp knife. In the case of the New Telecommunication Building built at Asansol, one inch thick jute fibre boards have been used for roof insulation. Poly coir is coir fibre board
composite, in which fibre used comprises 75% of the total weight. The
steps involved during fabrication is the production of needled felt
which is resin impregnated and hot-press moulded. The low density and
the medium density products are porous in nature having rough surface.
But the high density product is smooth, glossy and flexible in nature
and resemble wood in appearance. |
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Can teleporting be a possibility? The dream of teleporting atoms and molecules — and may be even larger objects — has for the first time become a real possibility after physicists have suggested a method that in theory could be used to "entangle" absolutely any kind of particle. Quantum entanglement is a property that allows two particles to behave as one, no matter how far apart they are. If the state of one particle is measured, the state of the other is instantly determined. This could one day mean teleporting of objects by transferring their properties instantly from one place to another, a report in New Scientist said. Until now, physicists have only been able to entangle photons, electrons and atoms, using different methods in each case. For instance, atoms are entangled by forcing them to interact inside an optical trap, while photons are made to interact with a crystal. "These schemes are very specific," says Saugato Bose of the University of Oxford. But Bose and Dipankar Home, of the Bose Institute in Kolkata, have now demonstrated a single mechanism that could be used to entangle any particles, even atoms or large molecules. To entangle the spins of two electrons, it needs to be ensured that they are identical in all respects but their spin. Then the electrons are shot simultaneously into a beam splitter. This device "splits" each electron into a quantum state called a superposition, which gives it an equal probability of travelling down either of two paths. Only when one tries to detect the electron does he/she know which path it took. If two electrons are split simultaneously, both paths could have one electron each (which will happen half of the time) or either path could have both. Bose and Home showed mathematically that whenever one electron was detected in each path, they would be entangled. While a similar effect has been demonstrated before for photons, the photons used were already entangled in another way, even before they reached the beam splitter. "One of the advances we have made is that these two particles could be from completely independent sources," says Bose. The technique should work for any object — atoms, molecules and other — as long as beam is split into a quantum superposition. Anton Zeilinger, a quantum physicist at the university of Vienna in Austria, has already shown that this quantum state is possible with buckyballs — football-shaped molecules of carbon. Although entangling such large objects is beyond the technical abilities at the moment, this is the first technique that might one day make it possible. Any scheme that expands the range of partciles that can be entangled is important, says Zeilinger. Entangling massive particles would mean they could then be used for quantum cryptography, computing and even teleportation. "It would be fascinating,"
he says. "The possibility that you can teleport not just quantum
states of photons, but also of more massive particles, that in itself
is an interesting goal." PTI |
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Cheaper flat-panel display Researchers have developed new silicon layers, used in flat-panel displays and solar cells, which promise to be more stable and cheaper than the present amorphous silicon layers. Flat-panel displays and solar cells have a substrate of glass or plastic, which is coated with a thin layer of amorphous silicon. The silicon layer is a semiconductor which, under the influence of a brief local voltage, becomes conductive for a fraction of a second. This property makes it possible to create a potential difference via the amorphous silicon which addresses separate pixels in an active-matrix LCD display, a report in NWO Research Reports said. However, the disadvantage of amorphous silicon is its instability. The threshold voltage needed to make the silicon conducting, changes if a prolonged gate voltage is applied. This is the case in thin film transistors, the
devices which address the pixels in a flat panel display. The microscopic
mechanism of this "metastability" is still not understood. PTI |
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NEW PRODUCTS
& DISCOVERIES Twenty-three years after the first Walkman, its natural successor — the handheld video machine — is ready for its close-up. A new compression format called MPEG-4 finally makes it feasible, and Korea-based MagicEyes Digital gives us a peek at what to expect with its $250 MkiVki. The tiny (3.7- by 2.8- by 0.9-inch) handheld is designed to synchronise MP3 music with images, but the company says future models will support full-motion MPEG-4 video. Philips has also shown a prototype that downloads video wirelessly from the Internet. The first personal video machines should hit the market within two or three years. — Popular Science New system to help prevent accidents Scientists are developing a system for the surveillance of the runway and flight trajectories of jet aircrafts for the purpose of apron monitoring, which can allow accidents to be explained more quickly, in turn making them easier to prevent. The need for such a system was felt as experts investigating air disasters find precious few clues as the probe gets underway. Months often pass, sometimes years, before the events leading upto an accident can be reconstructed with any precision. "Based on our Site View video monitoring system, we can fully document take-off and landing approach in 3D. Such a system could set off an alarm, for example, if an aircraft suddenly loses a part, or if another plane is blocking its path, explains Gunther Grasemann of the Fraunhofer Institute for Information and Data Processing IITB in Karlsruhe. Site View was originally developed for motion detection for a wide variety of objects. Generally, the user can employ the video cameras they already have in place for that purpose, a report in Fraunhofer Gesellschaft said. The filmed sequences are evaluated on the basis of an image processing technique developed at the institute, which is largely resistant to the effects of shadow movement, changes in light intensity and even weather effects. The scientists can configure the system according to the user’s requirements, so that only the data needed are filtered out of the glut of the video imagery. Object size is given in metres, with speed in metres per second. Almost universally deployable, the system is especially well suited for monitoring buildings. Apart from monitoring the movement of persons, Site View also offers a range of further options for use — it can record traffic flow, measure visitor frequency or create motion profiles for athletes. PTI Fighting coal fire with satellites Indian scientists are using satellites to detect fires in underground coalmines in Jharia in Bihar. "Besides causing land subsidence and environmental problems, the fires have already destroyed 40 million tonnes of coal and have locked up otherwise exploitable reserve," according to Mr Vinay Kumar Srivastava of the Department of Applied Geophysics at the Indian School of Mines in Dhanbad. "The Jharia coalfield is India’s only source of cooking coal required for steel making and the coal fire is causing a huge national loss," he told the National Space Science symposium that concluded recently in Bhopal. Mr Srivastava said that by using satellite imageries his group had successfully delineated the pockets where the fire is raging. "Around 19 coal fire areas have been identified covering an area of around 129 sq km." According to Mr Srivastava, the underground fires have been raging for several years but the satellite imageries have for the first time given the precise location and extent of the fires. "Using this knowledge one can scientifically plan the mining operation in such a way that vulnerable seams are worked first before fire spreads to them." Mr Srivastava said that he used
imageries from American Landsat-4 satellite. Some fires are big and
some are small and while 60 per cent of the fires are totally
underground the rest have spread upward to the surface, he said. PTI
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SCIENCE & TECHNOLOGY CROSSWORD
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