|SCIENCE TRIBUNE||Thursday, March 8, 2001, Chandigarh, India|
Plastics that conduct electricity
Bhuj quake from a geologistís perspective
Earth is a dynamic body. Just as we enjoy its natural beauty, consume its bountiful resources, adore its bond to our lives, we also need to be prepared to face its fury. When earth moves, fire, flood, avalanche, rock-showers, death, and destruction reigns the landscape. if we adjust our lives to accommodate earthís movement, then death and destruction can be minimised. Bhuj earthquake is a small measure of earthís movement along a crack in the ground. If an earthquake awareness and preparedness was initiated, the loss of life and property could have been reduced. With this in mind, I have prepared a review of the Bhuj earthquake so that those who are living in the "Earthquake Country" can prepare themselves against the future shocks.
Earthquakes in India are mostly confined in the Himalayan belt and along the flanks and also on the continent.
One of the major earthquakes of the world occurred in Kutch on June 16, 1819 (magnitude=8.0). It happened after 182 year. It was along a fault (huge crack) called Allah Bund (140 km long). Four major faults are present in the area. The area falls in Zone V (Highest Risk Zone for Earthquake) similar to many Zone V areas located in the Himalayan belt. Just as Himalaya has risen over the last 50 million years, areas in Kutch like Katrol and Kaladonga have risen to about 400 metres in the past two million years. While certain hilly areas have been rising, there are some areas that have been sinking (like Sindree port area). Seismologists in India had been expressing concerns in this area. High seismic activity in the region was noted last year. During August-September, 2000, small tremors had shaken Bhavnagar; at one time 68 tremors occurred, forcing people to sleep outside.
Earthquakes in India are mostly due to overall seismicity caused by Indian Plate pushing into Euroasian Plate. This is derived from a concept called Plate Tectonics which states that earth is divided into 12 plates that are sliding on mantleís upper part. In other words, plates of the crust (uppermost part of the earth) are being carried on a conveyor belt in mantleís upper part which brings us to the realisation that Earth is a Dynamic Body ó Always in Motion!
Now, let us go back to the tectonic history of India. About 200 million years ago (mya), India separated from Pangea (continents all united into one mass) and began to move northward. In between India and Euroasian continent, there was a sea called Tethys. Thereafter, the history (per USGS) is as follows:
a) 80 mya ó India was moving at about 9 m per century and was still about 6400 km from south of Asia.
b) 40-50 mya ó India pushed into Asia, the speed slowed down to about 4.5 m per century.
c) Because of collision of two continents, neither is subducted because the continents are made of lighter rocks. Itís like two ships colliding.
d) As a result, the crust started buckling, raised the Himalaya mountain on the Indian Plate and Tibetan Plateau on the Asian (same as Euroasian) Plate.
e) It took millions of years for Himalaya to rise to more than 9 km (most growth took place during last 10 million years).
f) Himalaya continues to rise at a rate of about 1 cm per year ó a growth of 10 km in a million year. But this is not happening. Otherwise Himalaya would rise even higher.
g) The Asian Plate may now be stretching rather than thrusting up which would result in subsidence due to gravity. Hence, itís now squeezing rather than rising which would result in building stresses which are being released as earthquakes periodically. A proof is the geologic distribution of earthquakes.
h) It should be kept in mind that the main seismic activity in India is due to impinging of India against Asia. The stress distribution decreases as one goes away towards the south. However, there are other earthquakes that may be due to other causes.
Can quake be predicted?
Earthquakes cannot be predicted. Following clues have been suggested: a) strange animal behaviour, b) tilting of ground, c) increase in rate of smaller earthquakes , d) gap in regular frequency of earthquakes, e) strain in the rocks, f) change in electrical conductivity of the rocks, and g) release of radon gas. Others have suggested various triggering mechanisms such as volcanic activity, magnetism, pull of moon, sun, and other planets. But the fact remains that none has been used to predict earthquake with surety. However, based on previous records, probability of earthquake can be calculated.
What to do during, before, and after an earthquake? USGS has prepared a list of activities that have been adopted by Red Cross, educational institutions, and many city and town governments in the USA. I am reproducing much of it for the benefit of all.
a) During an earthquake: i) If you are indoor: Follow the rule of DU-CH (Duck, Cover, and Hold under a strong piece of furniture). If there is no furniture, stand under a doorway. If you are in a highrise building and way from a furniture, move against an interior wall and protect your head with your arms.
Donít use electrical, gas equipments.
ii) If you are outdoor:
Move away as far as possible from the building, tall structure, power lines, etc.
iii) If you are driving:
Slow down, move to a clear area (if possible), stop and stay inside until shaking stops.
b) After earthquake:
i) Wear safety gears (specially heavy shoes).
ii) Check for hazards (fire, gas, electric wires, spills, etc.); shut off all the valves.
iii) Provide first aid.
c) Before earthquake:
i) Plan earthquake preparedness with family, neighbours, and friends (Talk about a meeting place to reunite and assign an out of town phone number of a relative to inform status).
ii) Keep emergency supplies in a plastic container (example: canned food, water blanket, first aid kit, flashlight with extra batteries and bulbs, fire extinguisher, portable radio, etc.)
iii) Know where gas, electricity, water main shut off valves are.
iv) Fasten structures inside the house that may fall during earthquake (e.g. refrigerator, furniture, bookshelves, etc.)
d) Build earthquake resistance structures:
One cannot construct a dwelling completely earthquake proof but it can be made earthquake resistant. Also an older building can be retrofitted to resist an earthquake. Process is followed in two steps:
i) Know the hazard map of the area:
Obtain a hazard map from the Regional Geological Survey office. A hazard map shows geologic problems, soil and bedrock conditions which will determine the behaviour of building during shaking.
ii) Incorporate earthquake resistant design:
A building collapses because when the ground moves, the building moves back and forth with the bottom of the building moving with the quake and the top tending to remain in place. Hence, one should make sure that all parts of the building are tied together as one unit and the entire structure is firmly anchored/bolted to the foundation. Also, the strength of the building material is high enough so that at any point along the structure during an earthquake, it overcomes both the vertical and horizontal forces and does not break away. A few steps are: bolt the building to the foundation, tie all the walls strongly, roof and floor to be well secured with the wall, walls are reinforced either with diagonal steel beams or the wall is made of reinforced concrete (concrete with steel rods). This must be done especially for those walls that are made of brick and concrete blocks. Many of the high rise buildings are anchored very deep onto the bedrock and are provided with "base isolators" between foundation and the building so as to act as shock absorbers.
Action plan: a) Initiate earthquake awareness
b) Build earthquake-resistant structures in seismic zone area
c) Force builders to adopt earthquake resistance code for structures
d) Strengthen the existing structures
e) Ask lawmakers to develop a strong programme of earthquake disaster preparation, mitigation, and management programmes.
The author is a Staff Scientist at Ispat Inland (formerly Inland Steel Company) in East Chicago, Indiana.
Plastics that conduct electricity
It is a well-known fact that plastics donít conduct electricity. In fact, the insulation used around copper wire in electric cables is made of plastic. But research in 1970s showed that plastics, with some modifications, could be made to conduct electricity. Even their conductance can be made as high as that of copper. This indeed is amazing. Soon this technology is expected to completely replace the current silicon-based microelectronics. The revolution is well on its way. Plastics, which are nothing but polymers, are likely to be the key to that.
The Nobel Prize for Chemistry for the year 2000 has gone to Hideki Shirakawa of University of Tsukuba, Japan; Alam G. MacDiarmid of the University of Pennsylvania, Philadelphia, USA and Alan J. Heeger of University of California at Santa Barbara, USA for their pioneering research on conductive polymers.
A polymer is a material in which constituent molecules repeat their structure regularly to form long chains. Conductive polymers are a sub-group of a larger group of organic and inorganic conductors. The trio of Nobel Laureates has extensively investigated a conducing polymer-polyacetylene. Their research has opened up a new field of research and applications. These scientists have found that a thin film of polyacetylene could be oxidised with iodine vapour to increase its conductivity a billion times. This sensational finding was the result of serendipity combined with collaborative research across continents.
Polyacetylene (pA) exist in two different structural forms (isomers): cis-pA and trans-pA. These isomers are ordinarily semiconductors. The trans-pA has more than a thousand times higher conductivity than the cis-pA. In 1970s Hideki Shirakawa discovered that he could polymerise acetylene in such a way that he could control the proportions of cis-and trans-isomers. By varying the amount of the catalyst and the temperature of the reaction, Shirakawa was able to produce entirely the trans-or cis-form of the polymer. This fact led to the discovery of conductive polyacetylene.
Around the same time, Alan J. Heeger of the University of California and Alan G. MacDarmid of the University of Pennsylvania were studying metallic film of the polymer sulphur nitride (SN) At a seminar in Tokyo, a chance meeting between MacDiarmid and Shirakawa led to the collaborative research between them. They involved Alan J. Heeger to carry out polyacetyleneís physical measurements. Their joint research activities led to the fact that oxidising the polymer with iodine vapour increases its conductivity by about 10 million times. They published the result of this major breakthrough in 1977.
Conductivities of polymers are generally very low. But the conductivity of doped polyacetylene is comparable to that of good conductors such as copper. The discovery of the conducting polymer polyacetylene has opened up a new field of research and applications, microelectronics being foremost among them.
The last two decades have seen an explosion of the conductive polymer research and applications. Today Polythiopene derivatives are being used in antistatic treatment of photographic films. They are also being used in devices to mark products in supermarkets. Another antistatic material i.e. doped polyaniline, is being used as plastic carpets in offices and operation theatres. It is also being used on computer screens as an electromagnetic shield and as a corrosion inhibitor.
Today, photodiodes and light emitting diodes (LEDs) with semiconducting polymers have become commercially very attractive. This is because of their highly efficient light generation, more energy saving and less heat generation as compared to ordinary light bulbs. Materials such as polydialkylfluorenes are being used in the development of new colour screens for television. Polyphenylenevinylene is used in mobile phone displays. Several semiconducting polymers find numerous applications such as in flat television screens based on polymer LEDs and in luminous traffic and information signs.
With easy availability of very high
purity polymers, several other semiconductor devices such as normal
transistors, field effect transistors and polymer-based integrated
circuits (I Cs) are on the horizon. From polymer-based electronics to
the fascinating world of real molecule scale electronics is the
technology of the future. Molecular electronics aims to put electronic
circuit properties into single molecules. Arrays of such molecules
connected by conducting polymer wires on a molecular base would form
molecular wafers. This would lead to the increase in the speed and
dynamic memory of computers by a factor of 100 million. Conducting
polymers would be the key players in such a molecular world. Today we
are at the threshold of witnessing such a plasto-electronics
NEW PRODUCTS & DISCOVERIES
With all the dust and grime in the atmosphere, scooter and motorbike driving can become a very tiresome chore. Now a simple new device is here to take away the stress of the road.
British designer Gordon Sparshatt has developed the Ziggy Bubble scooter. The scooter is encased in a two-sided clear material made from plastic glass.
The fortified glass made of super strong material used in aeroplane windscreens is framed around the scooter giving the rider both protection from pollution and safety.
The scooter is being considered an engineering marvel and in the years to come may revolutionise two-wheeled driving. The practical contraption has already found a number of interested buyers and is likely to go into commercial production later this year. NF
A revolutionary, hygienic mop
UK-based researchers have developed a hygienic mop which can absorb three litres of fluid, and dry a surface in seconds.
The U-shaped mop is more a health and safety product than a cleaning item. It reduces the cost of dealing with a spill to about £ 1 and the innovative implement could land the company a financial bonanza, says a report in British Commercial News.
The disposable mop, developed by Dacoma Ltd., is not designed to be washed or wrung out, and obviates the need for the use of conventional implements-mop, bucket of water and wringer when dealing with a spill.
It locks the spilled fluid and small glass shards, if a bottle has been broken, into a gel in the mop head which can then be removed and disposed of appropriately without the user having to touch the contaminant.
The mopís U-shape also ensures that large pieces of glass are gathered safely in the mouth of the mop, enabling the pieces to be collected later. The mops will not drip aqueous fluids and can be used up to three times before disposal. PTI
Smart greenhouses for 21st century
Scientists in UK have developed "smart" greenhouse cladding material which reduces the need for pesticides and plant growth regulators, by selectively filtering undesirable wavelengths and allowing useful ones.
The research has significant potential to reduce the environmental impact of conventional horticulture, agriculture and food production. Significant amounts of fungicide are normally used to control highly destructive diseases, such as botrytis. Similarly, producers of ornamental plants are highly reliant on the use of growth regulators to control plant shape and quality.
Internationally, polyethylene is the most important material used to clad greenhouses.
The new product will also offer growers a novel means for reducing both losses from botrytis and their reliance on chemical growth regulators. It will also benefit consumers as they will be able to purchase crops which have been produced using lower levels of pesticides. Growers, thus will be able to cut the chemical costs. PTI
System that spirals away wastewater
A new treatment system for cleaning wastewater has been developed which is 30 times smaller than conventional processes and is more efficient.
The new system uses plastic fins that rotate in interlocking spirals. The fins are fitted inside a circular tank and as they rotate they act as separators, sending cleaned water to the top of the rank from where it can be drawn for further treatment and waste matter to the base for easier disposal.
It has been invented by an engineer working for United Kingdom company Southern Water and took several years in development. The system also saves space and money on restricted sites.
The invention is being installed at the companyís new wastewater treatment works at Newhaven, on the southern coast of England.
The system is also due to be installed at five other sites run by Southern Water and the idea has already been adopted by a second water company in another part of the country, according to a report in British Commercial News. PTI
Solar lantern lights up a better life
Life in households without mains electricity can be radically transformed by a new simple solar lantern, developed by scientists.
The problem with the high-power solar systems was that they were plagued with short-level rechargeable batteries. The new Glowstar solar lantern kit, is a purpose-built sealed unit containing its own rechargeable battery.
The lantern has a new type of microchip charge regulator. The microprocessor-based charge control circuit housed in the lantern constantly monitors the battery to ensure that it remains charged. At night it switches off the lantern rather than allow the battery to go flat and can control how much solar energy is conveyed from the solar panel to the battery during the day. PTI