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| SCIENCE & TECHNOLOGY |
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New products & discoveries Prof Yash
Pal THIS UNIVERSE |
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The future of car technology ELECTRICALLY
driven vehicles work just as well as those fuelled by petroleum (gasoline) and diesel oil provided they generate enough current. Therein lies the snag. The standard car battery produces barely any electrical power and if you tried to run a family car on it, you wouldn’t get far. Yet electric cars make hardly any noise and emit no fumes at all. They would give us far cleaner, quieter roads. Unfortunately they’re still a long way off. Or are they? The “fuel tank” of an electric car is a set of heavy, cumbersome lead acid batteries producing nothing like the power of the petrol and diesel engines which carry us hundreds of miles without refuelling. Electric car enthusiasts talk about recharging their cars overnight then plugging them in again when they arrive at work to top up power for the journey home. But presently it takes just a few minutes to stop at a service station, top up the fuel tank, pay the bill and drive on. Lead acid batteries take several hours to recharge, so persuading us to abandon the convenient, speedy and comfortable cars we drive at present is going to be exceedingly difficult. Traditional lead acid batteries just don’t cut the mustard. Every decade since the 1950s another group of would-be electric car designers have abandoned their project, vowing to return to it when someone comes up with a compact lightweight battery. That wait may be coming to an end with the introduction of fuel cells. Fuel cells are essentially electric generators small enough to fit inside a car’s engine compartment. One of the facts you may remember from school science lessons is the basic formula for water - H2O - two atoms of hydrogen and one atom of oxygen; and you may even recall that these two constituent parts can be separated by passing an electric current through water; a process that consumes electricity and is called electrolysis. Electrolysis can be reversed. Combining hydrogen and oxygen in a fuel cell produces electricity, and the only emission from a car powered by a fuel cell is water; hardly a noxious pollutant. The driver of a vehicle powered by a fuel cell fills his tank with hydrogen, switches on the engine and drives off. Burning hydrogen with oxygen from the atmosphere, the fuel cell feeds electricity to the motor and the hydrogen tank holds enough gas for a long journey without frequent topping up. Fuel cells make excellent batteries and have been used for decades where mains electricity is unavailable, as in spacecraft. But people are understandably nervous about the thought of volatile hydrogen being stored in tanks at local fuel stations, and its small molecule does allow it to leak readily through the tiniest of holes.
Hybrid cars Hydrogen-powered cars can’t solve the energy crisis because the manufacture of hydrogen requires vast amounts of electricity to electrolyse sea water. But in a world that may be running out of oil, it’s good to know an alternative form of automobile fuel exists, even in theory. Petroleum and diesel oil are still the norm and the idea we might convert to new technology in the immediate future is probably naive. Much as we may want to improve our environment and to save energy, we still need to fill our tanks with familiar fuel. This is where hybrid cars can come in. Significantly more costly than conventional vehicles, hybrid cars are presently thin on the ground. Yet they may represent the future for motoring in cities, and already thousands are being made. The hybrid car combines electric and diesel power. It is driven by an electric engine powered by a conventional battery. When after a short journey the battery runs flat, the diesel motor automatically switches on. That operates an electric generator recharging the battery which again becomes the motive power when it is fully energised. Relying on diesel oil, the hybrid car continues to emit pollutants and because it uses two engines it is complex to maintain. But it can cover the same distance as a conventional diesel-powered vehicle on half the fuel. The hybrid car performs best in cities where the conventional vehicle wastes fuel and energy when idling at traffic lights, stopped at street junctions, stuck in jams. When it is able to start moving again, its engine revs are less than optimal as its driver moves through the gears. By contrast an electric car consumes power only when it is moving. When it stops the electricity consumption is nil. The battery and the electric motor operate as an interface between the diesel engine and the wheels. The engine switches on when the battery is low and switches off when the battery is fully charged again. Fuel is never burnt unnecessarily. Inevitably there is some waste of energy in the transfer of motive power, but the latest hybrid car is fitted with a device to counteract the loss. When you brake suddenly, you smell burning from tyres and brakepads. Designers have contrived to obtain electrical energy from the friction and feed it into the battery to improve fuel consumption. Now they are working towards thermo-electric recovery from engine heat via photovoltaic cells laid on the car roof. These won’t produce enough power to move the vehicle at speed but they could increase its range. Since most commuters park in the open, their car batteries can slowly be recharged while the vehicles are idle. Touch a diesel engine that has run for some time and you’re likely to burn your fingers. It may be possible to salvage further electricity from the warmth of a hybrid car’s diesel motor. Manufacturers of hybrid cars aim to milk every drop of energy available and optimistic calculations suggest a possible 50% saving in overall fuel consumption. Wealthy enthusiasts like Harrison Ford drive these innovative vehicles already and tens of thousands of them are being manufactured. They constitute a realistic, practical way to limit noise and air pollution while reducing dependence on fossil fuels. Hybrid cars may well become a common sight on our roads within the next few years. Fuel-cell vehicles may not make their appearance for at least another decade but it’s comforting to know that a pollution-free concept is around the corner.
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New products & discoveries TISSUE engineers can choose from a wide range of living cells, biomaterials and proteins to repair a bone defect. But finding the optimum combination requires improved methods for tracking the healing process. New Georgia Tech research points to better ways to heal and regenerate bones using microcomputed tomography (micro-CT) imaging — a process 1 million times more detailed than a traditional CT scan. The new micro-CT scan technique simultaneously looks at both vascularisation (the process by which blood vessels invade body tissues during repair) and mineralisation (the process by which mineral crystals form to harden regenerating bone) by collecting three-dimensional images in vitro and in vivo. A galaxy minus stars It looks like an empty patch of space, but astronomers say it holds a galaxy that contains no stars. If Robert Minchin of Cardiff University in Wales and his colleagues are right, they have found the first member of a population of galaxies that theorists have proposed but observers had never seen. In 2000, Minchin’s team noticed two apparently isolated hydrogen clouds in a radio telescope survey of the Virgo Cluster of galaxies. Follow-up observations with visible-light telescopes showed that one of these clouds was associated with a faintly glowing galaxy. However, long exposures taken with the 2.5-meter, visible-light Isaac Newton Telescope in the Canary Islands offered up a surprise: The second cloud had no partner glowing galaxy. That distant blast Forget “Independence Day”or “War of the Worlds.” A monstrous cosmic explosion last December showed that the earth is in more danger from real-life space threats than from hypothetical alien invasions. The gamma-ray flare, which briefly outshone the full moon, occurred within the Milky Way galaxy. Even at a distance of 50,000 light-years, the flare disrupted the earth’s ionosphere. If such a blast happened within 10 light-years of the earth, it would destroy the much of the ozone layer, causing extinctions due to increased radiation. Why North Pole is frozen Ice has been building up in the Arctic for 2.7 million years. Until now, no one has been able to prove what mechanism brought about this accumulation of ice. However, a team of international scientists led by Antoni Rosell, a researcher for the Universitat Autònoma de Barcelona, and Gerald H. Haug of the Potsdam Institute for Climate Impact Research (Germany) has discovered the mechanism that set off the accumulation of ice. A sudden fall in average world temperatures 2.7 million years ago caused the Arctic Ocean to freeze and Europe and North America to become covered in ice. The reason seems obvious: the cold temperatures caused ice to build up. But the drop in average temperatures is not enough to explain why so much ice built up and has remained to this day. For many years, scientists have been speculating on what caused this accumulation of ice and have proposed many theories. |
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THIS UNIVERSE Q. Why does hair colour change to white as we become old? Is there a way to stop this? A. Hair is string of dead cells. The only portion of the hair that is alive is at the follicles on the skin. The colour of hair is due to the melanin manufactured by the skin cells. Your question then becomes “Why do the skin cells near the hair follicles stop manufacturing melanin when people grow old”. One might as well ask “why do people grow old”? I think this is built into the programme of all living things. Some organs and systems function less efficiently as we age. Many of us need spectacles to see properly after the age of 45 years. Our teeth fall off. The skin becomes lose and wrinkled. We develop arthritis. Our bones become weak. We cannot run as fast. Wounds take somewhat longer to heal, etc; the list goes on. We all know that growing old is a period of physical descent. It may not be uniform for all of us. There might be individual differences in the rate of decline, depending on genetics, or lifestyle. A lot may be known in this regard, but there is still much to discover. Q. Why do antibiotics not affect virus? A. An antibiotic is an agent that interferes with the development machinery of an undesirable biological invader. On the other hand, a virus does not have its own machinery. It is pure information that takes hold of the metabolic apparatus of the host. In the process it also replicates itself. Since a virus does not need to eat or grow, it can lie dormant and survive for long periods under very adverse conditions. It has been suggested that viruses could also survive the vacuum of space! Viruses are like fundamentalist rhetoric. The only way to avoid damage is to keep it away from “hosts” that would make it bloom. If the virus is forced to lie dormant for a long time it can perhaps wither away. The thought occurs that lot of mutual understanding might emerge from a collaboration of computer scientists (who deal with the menace of software viruses), medical scientists and social engineers. Conventional antibiotics were isolated from fungi, on the basis of the observation that they could inhibit the growth of bacteria. The term has, therefore, come to be associated with anti-bacterial activity. Compounds that have potent anti-viral effects have been developed (for example AZT and protease inhibitors) that prevent the growth of the HIV virus and have prolonged the lives of many patients. Many labs are also investigating the effects of extracts from plants such as neem for anti-viral activity. |
