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Biodegradable plastic Prof Yash
Pal
This Universe
Trends
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Biodegradable
plastic However, there is no move as yet to impose a blanket ban on the use of polythene bags and related plastic items which because of their nondegradable nature have become an environmental hazard. In many Indian cities burning of the discarded plastic goods is contributing to the problem of air pollution. However, the large-scale introduction of biodegradable plastic has its own limitations. First it would be more expensive than the conventional plastic. Second, it would not be as much water resistant as conventional plastic and chances of its meltdown after exposure to rainwater is quite pronounced. As things stand now, producing more water resistant biodegradable plastic will be a costly preposition. The technology for producing biodegradable plastic has not advanced to a level where industries can produce ecofriendly plastic at a price equal to that of conventional plastic. According to the International Standards Organisation (ISO) biodegradable plastic is the one in which degradation results from the action of microorganisms. Of course, the speed at which the plastic degrades depends on factors such as the polymer type, the concentration of active components in the polymer as well as atmospheric conditions. Normally, biodegradable plastic is produced out of natural substances such as starch and cellulose. Significantly, research studies have gone to show that the biodegradable plastic trash bags containing 6 per cent corn starch and 94 per cent synthetic polymer decomposed within five years. Scientists at the Thiruvananthapuram-based Central Tuber Crops Research Institute (CTCRI) functioning under the Indian Council of Agricultural Research have perfected the technology of producing a biodegradable plastic using starchy material derived from tapioca and other tubers. This bioplastic is known to degrade in just six months. According to R. Clinton Fuller of the University of
Massachusetts at Amherst, the success of a biodegradable plastic depends directly on the evolution of a cost-efficient production technology coupled with a large market demand. Many universities and industrial outfits are actively engaged in making bioplastic out of natural substance. In the US, Biochip North America is producing items such as garbage bags, cups and bins using biodegradable plastic. Recent advances in biotechnology have enabled researchers to coax the tiny bacteria to produce bio polymer from which bioplastic could be manufactured. Though as far back as 1925, scientists were aware of the bacterial strains capable of yielding biopolymers, it was not until mid-1980s that researchers were able to extract biopolymer produced by bacteria. To a large extent, basic ingredients of biodegradable plastic are derived from renewable raw materials, including farm products. In recent years, biodegradable plastic developed out of the materials derived from soyabean has been in use in the US. What’s more, biodegradable materials such as bamboo, fibre, cereal shells, chitosin, gums and polymer blends are being studied to engineer biodegradable plastic varieties that are both inexpensive and convenient to use. |
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This Universe
I am 73 years old, a science graduate and an electronic engineer. Have lived by the sea, studied oceanography and served along the entire coast of India. Yet I am unable to understand how high and low tides occur. They taught us that the moon and the sun are responsible, in addition to rotation of the earth. This remains vague and unconvincing. I can understand that the moon on one side of the earth can cause rise of water level in the sea, but how can it simultaneously do this at points 1800 opposite? Please explain, because many school children would also be benefited. I thank you for your letter. It shows how some of the standardised text in our schools is fit only for passing examinations and to the extent it deprives children of real understanding it leaves life long scars. Let me see if I can provide you with a little joy of understanding. Tides are caused by tidal forces. But what is a tidal force? In simple words it is the difference in force on two opposite sides of an object. In the case of the earth-moon system the tidal force on earth would be the difference between the gravitational attraction of the moon on a particle on the moonward side and on another one on the opposite side of the earth! Both sides are attracted towards the moon but the near side is attracted significantly more. The reason is that the force of gravity decreases as the square of the distance. Force of gravity is proportional to the product of the masses and inversely proportional to the square of the distance. This is expressed as Gm1m2/r2. Here G is the universal gravitation constant, m1 and m2 are the masses of the two objects. These two objects could be the moon and the earth or the sun and the earth depending on our interest. The difference between the forces on two sides of an object at distance r (the Earth, for example) would be proportional to 1/r3 (the differential of 1/ r 2). This is how the tidal force varies with distance. This is the basic thing to understand. The actual height of the tide would be affected by local topography as also effect of the angular momentum of the two objects, but that is of secondary importance. The basic reason for tides (for the earth moon system, for example) is that the differential attraction between the moonward and anti-moonward sides leads to a stretching force causing a bulge in the ocean on both the sides. |
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India has the highest number of diabetics in the world. Convergent Technologies with its headquarters at Frankenberg, Germany, has launched “ELEGANCE” range of blood glucose monitoring systems here. The system is based on state-of-the-art Amperometric Biosensor technology. The tests require as little as 1.8 micro litre of blood and the plasma calibrated blood glucose results could be read in 10 seconds. The system has a memory of 450 tests results with date and time. One time coding and interactive data download software are other features that make the system extremely user-friendly. The system is suitable for professional as well as domestic use. Convergent Technologies (www.convergent-technologies.de) is an emerging leader in the Point of Care diagnostics with a special emphasis on diabetes diagnosis and monitoring. Healthy junk food Junk food could be made healthier by adding an extract of an exotic type of seaweed, say British scientists. The highly-fibrous seaweed extract, alginate, could be used to increase the fibre content of cakes, burgers and other types of food which usually contain large amounts of fat and a low degree of healthy nutrients, say the team.
Pack rats’ rubbish For a person, life as a pack rat is one of obsessively collecting, say, newspapers, computer parts, food containers, or maybe all of these. But a literal pack rat gathers plant fragments, bone bits, fecal pellets, and even, occasionally, eyewear. “A friend of mine lost his glasses to a pack rat,” says Kenneth Cole of the U.S. Geological Survey in Flagstaff, Ariz. In the September Geology, Cole and a colleague report that pack rats’ fossilised collections, secreted away for millennia in caves and rocky overhangs, can improve the portrait of global temperatures at the end of the last ice age.
Saving the flowers In 1940s, there were only a few flower varieties: red, white, yellow, and pink. Now, there are thousands, but only a few have a lot of scent. No one knows what’s responsible for this waning of fragrance by roses and other ornamental-flower varieties, including carnations and chrysanthemums, but scientists who investigate floral scent suspect that the flower breeding that’s led to an estimated 18,000 rose cultivars in an ever-widening spectrum has run roughshod over fragrance. |
For many years now eco activists in India and other parts of the world have been vigorously campaigning against the use of plastic in general and polythene carrybags in particular. In many Indian states there are stringent regulations on the use of polythene bags which are expensive but convenient to use.