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| SCIENCE & TECHNOLOGY |
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Coal makes a comeback
Anti-freeze gene
Voice over Wi-Fi Trends Prof Yash
Pal THIS UNIVERSE |
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Coal makes a comeback A
chemical engineer, Dr John Dennis, working at Cambridge University, UK, is working on a method of generating energy from coal without actually burning it. The process releases the energy of the coal, in the form of only steam and virtually pure carbon dioxide as byproduct. The new method could form the basis of thermal power stations whose carbon dioxide emissions could then be easily captured and stored and used elsewhere. The technique combines two chemical processes — one well established, the other new. The technique could have huge potential in the energy-hungry, rapidly industrialising countries like ours. Dr Dennis’s technology “burns” the coal chemically, first converting its carbon content into a gaseous mixture of carbon monoxide and hydrogen, known as synthesis gas or syngas, and then bringing this into contact with a solid metal oxide, which can easily lose its oxygen. The system uses a technique known as chemical looping, where a single reactor serves several different functions one after the other. The reactor is a type known as a fluidised bed, where a thick layer of granules is made to act like a liquid by a gas pumped upwards through it at high pressure. In Dr Dennis’s system, the granules initially consist of a porous solid such as aluminium or titanium oxide, supporting a layer of a copper oxide. To start with, the bed is fluidised by steam at 800-1,000°C, and powdered coal is fed into the reactor to mix with the copper-containing granules. The hot steam reacts with the carbon to produce syngas. Known as cool gasification, this has been used for many years in oil-poor, coal-rich countries. Syngas will itself burn readily, although it produces the same type of flue gas as burning any other hydrocarbon. The next phase of the process, occurring almost simultaneously, sees both syngas components reacting with the copper oxide, transforming hydrogen into steam and CO into CO2. Many metal oxide could perform these reactions, but only copper will do it while releasing heat from both the hydrogen and the CO. This energy can be captured in a heat exchanger and used to generate the high-energy steam needed to turn turbines in a powerhouse as in a convention thermal power plant. After a time, the coal feed into the reactor is stopped and the remaining coal in the reactor is allowed to gasify and react, using up the remaining oxygen content of the copper oxide. Once this process is completed, the flow of hot steam into the reactor stops and is replaced by hot air, whose oxygen recombines with the copper to regenerate the copper oxide. The process then “loops around”, with the steam and coal feeds beginning again. The steam can be condensed to collect the carbon dioxide. The process is simple and cheap. The carbon dioxide could be used for injecting in exhausted oil wells for enhancing oil production. The new method could form the basis of thermal power stations under construction in India. Once seen as yesterday’s fuel, coal is making a comeback. Vast untapped reserves — and a high growth in demand for electricity — mean that coal-fired power stations are likely to be the fastest-growing power generation units in the coming decades. But burning coal is a serious threat to the environment. Burning of coal creates the largest amount of CO2 than any fossil fuel. The hazards of burning coal and the resulting increase in carbon dioxide content in the atmosphere causing greenhouse effect are
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Australian
scientists have discovered an “anti-freeze gene” that allows Antarctic grass to survive at minus 30 Celsius, saying it could prevent multi-million-dollar crop losses from frost. “It’s a gene from the saltgrass that managed to colonise the Antarctic peninsula called Antarctic Hairgrass,” said Prof German Spangenberg from La Trobe University in Victoria state. “We identified a novel class of a gene protein which binds twice and that prevents ice crystal growth. It has the capacity to survive being frozen rock solid and then thawing. It prevents the damage from ice crystals,” Spangenberg says. The scientists implanted the “ice recrystallisation inhibition gene” into a host plant in Australia and replicated the anti-freeze properties. “Now we understand how it works we can use this knowledge for crop improvement, for frost and cold tolerance,” said Spangenberg. Victoria Minister for Innovation John Brumby said the discovery of the “anti-freeze gene” could prevent millions of dollars in lost crops due to frost and wintry conditions. “Over the next few years we should see the development and application of technologies for frost tolerance in crops based on the knowledge gained from the functional analysis of these anti-freeze genes,” Brumby said in a statement. Globally, between 5 and 15 per cent of agricultural production is lost to frost each year.
— Reuters
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Wojtek Felendzer held a mobile phone to his ear as he walked across the room, the call automatically switching behind the scenes from a Wi-Fi wireless hotspot to the regular cellular network. “Can you still hear me?” the Nokia Corp. employee asked. “Yes,” the reporter answered. “That’s good,” he said. “This is seamless handover. The voice didn’t drop. Nothing bad happened.” While Felendzer took only a few steps, his demonstration at the CTIA Wireless 2006 conference in Las Vegas proved that mobile Voice over Internet Protocol, or VoIP, technology has made a meaningful step forward. For years, Wi-Fi telephones and walkie-talkie like communicators have been available for hospitals and offices. Now, manufacturers and mobile carriers are preparing to link standard cellular networks to the mishmash of Wi-Fi hotspots, a move that will expand coverage and perhaps make cheaper mobile minutes a reality. The technology, called Unlicensed Mobile Access, or UMA, will help those who have high-speed Wi-Fi routers overcome any poor coverage in their houses or apartments. It’s also a way for mobile carriers to expand their footprint without spending lots of money on new infrastructure. UMA could enable users of souped-up handsets, wirelessly download content at broadband speeds at home and take that on the road when they leave.
— AP |
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Trends
IN follow-on work to last year’s groundbreaking invention of the world’s first single-molecule car, chemists at Rice University have produced the first motorised version of their tiny nanocar. The research is published in the April 13 issue of the journal Organic Letters.
Blind mice see Scientists have prompted mouse-eye cells that aren’t normally light sensitive to respond to light. This strategy could lead to new treatments for retinitis pigmentosa and related diseases, which cause blindness in 1 in 3,000 people worldwide. The new work took a gamble on some preliminary findings that indicated that other cells in the retina continue to function after the rods and cones die. These spared cells include inner retinal neurons, nerve cells that process information from rods and cones before sending it to the brain.
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THIS UNIVERSE During foggy evenings of winter or cloudy nights of summer, North Western horizon of the sky appears orange in colour (9 to 11 pm). Why? Even after some darkness has settled on the ground upper reaches of the atmosphere still get some light from the setting sun. This light is filtered through a long path in the atmosphere because of its near tangential passage. It is known that scattering in air is discriminatory between colour constituents of white light. Blue scatters almost 16 times more than the Red end of the spectrum. Therefore, the tangentially travelling sunrays lose most of their blue and neighbouring colours by the time they hit the fog or the clouds at great heights in the Western atmosphere. The light illuminating them is mostly orange which the water droplets scatter back to you. Incidentally this is also the reason that makes the setting sun looking orange. Kindly tell me why clouds don’t fall like a rock to the ground? Clouds are up there because they are made of water vapour that is near dew point — the vapour has condensed into tiny droplets of water whose motion is controlled more by movements of air in which they are suspended than by downward force of gravity. If the cloud transforms into a thick fog and there are no air currents then it would descend to the ground slowly with a terminal velocity so low that it might take hours to come to the ground. This is often seen in hill valleys. Tiny particles cannot descend to the ground like a rock because as you get small the ratio of the surface area to mass becomes large. Raindrops are heavier. They are formed by coalescing of fog particles and acquire a diameter as large as a millimeter. Even they cannot fall like stones or bullets because increasing air resistance reduces their terminal velocity. When a plate of food is heated its energy content and therefore its calories must go up. So does eating hot food make us fatter than eating cold food? It is good that you recognise that there is some common way of measuring energy content. You would see the fallacy of your hypothesis when you are told to get all the requirement of your food through drinking hot water. You do not get fat through input of energy, unless that energy is a result of metabolism that occurs in the body. Input of heat through hot food or sitting in the sun won’t do. If you have a weight problem do not worry about eating hot food or drinking hot water. Actually hot water might help you to better metabolise the food you eat and reduce
accumulation of fat. |
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