Repellents that kill slowly
Roopa Vajpeyi and Madhu Saxena
MOSQUITOES have been man’s unwelcome companions since time immemorial. They have been always biting men, sucking their blood and merrily flying away. It has been discovered that they are attracted towards or get distracted from certain odours and aromas, which help them to choose the person whom they wish to bite. Based on this property certain products called mosquito repellents have now been manufactured to repel them off.

NEW PRODUCTS & DISCOVERIES

• Building a bridge in a hurry
• Heavy metals from waste water
• Autonomy with solar cells
• New bus-tram on test

SCIENCE QUIZ
J. P. GARG TESTS YOUR IQ

Science outpost in space
Pravin Kumar

THE crew of the space shuttle Atlantis, which blasted off from Florida, have installed a 6½ ton air-lock on the International Space Station (ISS), a soda-can-shaped structure which is whirling 580 km above the earth, circling the globe every 92 minutes.

The air-lock mission will mark the completion of the first phase of the station’s construction, which was begun in December, 1998. The air-lock, called Quest, is a cramped antechamber where space-walking astronauts will wait till its air leaks out and the air pressure is equal to the vacuum of space, will allow the station crew to tend their orbiting home, conduct external experiments and make repairs outside the station. It will also allow a seven-man crew to live and work independently in orbit. The mission is the tenth dedicated to building the science outpost in space. With the air lock installed, the orbiting outpost is set to become a fully functioning space-station.

The assembly of the Space Station began in December, 1998, but is expected to be fully operational only in 2005. Last October, the first three-man crew, two Russians and an American, took up residence in the station, where they had been shipped by a Russian Soyuz rocket. When completed, the station will be the largest-ever structure assembled in space. Measuring 356 feet across and 290 feet long and seven storeys high, and weighing some 460 tons when complete, the ISS will enclose more than 1,717 cubic yards of pressurised space. That’s more than four times larger than the Russian Mir and the American Skylab (both now defunct). There will be six laboratories aboard the ISS — a European, a Japanese, a Canadian, a Russian and two American modules.

The station had its genesis in the mind of Jim Beggs, a NASA administrator, who in the summer of 1982 attempted to sell the concept of a human base in orbit to the scientific community. Two months later, the U.S. National Research Council (NRC) gave the thumbs-down signal for the idea. However, their report admitted that there was a special relationship between the station and life science, adding that studying human, animals and plants in zero gravity would be a pre-requisite for long-term space missions. The NRC’s space biology and medicine committee gave Beggs a summary of the space station’s potential for physiological and fundamental biological research. In 1984, President Ronald Reagan announced the project, initially as a U.S. — only venture, to compete with the Soviet space station.

Cost has been a bugbear from the beginning. Design difficulties bloated up cost estimates of $ 10 billion, with nothing to show for it. To help spread the funding, the Reagan administration invited international participation. Eleven European nations became partners. In 1993, Russia became the 16th partner, and the station’s design was scaled down to make it more affordable.

In 1999, European researchers offered nearly 100 entries in a continent-wide competition for instruments to hang outside the station. Of the 27 life-science experiments, more than one-half came from outside the USA.

With funding a crunch, scientists are wondering whether the quality of ISS science will suffer. For instance, Margaret Geller, an astronomer with the Harvard-Smithsonian Observatory in Cambridge (Mass) said that "people were jumping on board to get the money". Will lover-quality science from a richer agency score over a top-rated project? Russia’s financial plight is believed to be behind its plans for launching a module to the ISS for commercial projects. Various agencies are jockeying for space in the ISS. In exchange for launching the European and Japanese modules, NASA has claimed title to almost half the space in each. The European Space Agency (ESA) is building the pointing device, a lab freezer and other equipment in exchange for the right to place two astronauts and a few experiments aboard. As Thomas Gaisser, who heads NASA’s committee on Cosmic Ray Physics puts it, "there is an admittedly political aspect "to place some of the instruments aboard the station".

In contrast, Russia, despite its cash crunch, has retained 100 per cent control of its science modules. Cocking a snook at NASA, as it were, last April, it took aboard the first space tourist, Dennis Tito, a U.S. businessman, who paid $ 20 million for his stay.

Sceptics argue that the research envisioned for the space station could as well be performed aboard the space shuttle. But NASA points out that the space shuttle flight lasts only two minutes, compared to the space station’s planned life of at least 15 years, thus providing long-term capability for human-tended experiments. The longer duration available aboard the ISS is one of the station’s plus points. Scientists using the ISS can plan experiments lasting months or years, compared to the fortnight, or so, that researchers using the space shuttle have to collect data. The station also enables scientists to compile larger, statistically more valid data sets by repeating experiments. It is true that research in space can be conducted as effectively and far more economically by unmanned spacecraft equipped with ground-controlled robots. But research on the station will be "cutting edge" research, which will change rapidly over time as new information comes in.

Cutting edge research includes fundamental science, as well as space exploration technology and biotechnology experiments. The research that is of direct interest to industry is of two types: improvement of industrial processes and product development. For example, micro gravity experiments in combustion science could lead to reduction of pollution, improvements in home heating and production of synthetic materials. Research in materials science could augur better-designed products on earth, ranging from contact lenses to car engines.

Research in gravitational biology and ecology could enable agricultural firms to grow hardier crops on "space farms". The ability to manufacture in micro gravity and in vacuum could enable the electronics industry to produce a new generation of semiconductors. Initially, the programme drew heavy flak from scientists for the hype about "factories in space". But this criticism would be muted if studies by Boeing Co., the ISS’s prime contractor, show that production in space of such products as semiconductors and metallurgical castings would economical.

Among the payoffs of the station will be information leading to better safeguards for space travellers to Mars and elsewhere. The first major scientific exercise aboard the ISS was Fred, a mummy-like, plastic mannequin that was flown earlier on the space shuttle. With hundreds of sensors encased in his mock organs, Fred will help scientists determine how much harmful radiation is penetrating the bodies of the Station’s crew members.

Researchers in other fields are also looking forward to extended experimental time aboard the ISS’s six experimental pressurised research modules and dozens of external payload sites. Combustion and materials scientists are planning to juggle with burning and solidifying metals to uncover basic properties. One of the station’s most intriguing offerings may be the study of how metals and other materials solidify in micro gravity. At present, the tug of earth’s gravity obscures the secret of how the complex, fern-shaped metallic crystals called dendrites freeze into shape. A U.S. and European-built materials science facility, which will suspend samples in a magnetic field, will be ready next year. U.S., Japanese and European researchers have plans for at least half a dozen large instruments that will be bolted on to the ISS’s exterior, where astronauts will monitor them.

Life scientists will try to find out how people, plants and even insects react to life in micro gravity. The US hardware that houses Fred bristles with more than a dozen instruments which astronauts will use to monitor their health. The human studies are considered "in many ways the most defensible studies, assuming you believe in manned space exploration", says one biomedical researcher. Side by side, Earth-bound researchers will try to frame answers to one of space travel’s most pressing questions: why does life in low gravity disrupt perception, promote loss and cause other health problems? Other studies that could eventually aid astronauts might show the latent viruses carried by crew members respond to the stress of life in orbit; and how genes involved in growth and sleep cycles behave in the absence of normal gravity.

Biotechnology experiments are already under way. These examine more traditional types of crystal-protein and DNA crystals grown in supersaturated solutions. In low gravity, diffusion in a crystal occurs more slowly and so crystals can grow in a more precise pattern, according to Craig Kundrot of NASA’s Marshall Flight Centre (Huntsville, Mass.). Such analysis could fine-tune developments of drugs designed to bind or target biological molecules. In a large-scale module scheduled to arrive in 2001, it is planed to study different ways of making crystals of germanium-silicon. If this alloy could be grown with few defects, it could be used to make more efficient solar cells and better optics to focus X-rays.

One handicap faced by researchers is that the station’s low altitude means that the mannequin Fred will not record data from further out in space, where earth’s atmosphere provides no protection from radiation. That will make the findings of little help to interplanetary voyagers. The low orbit also makes the station useless to many astronomers, as earth’s atmosphere, for earth’s upper atmosphere blocks many forms of light and radiation and prevents some kinds of instruments from getting an unobstructed view of distant objects. The drag of the earth’s atmosphere will also make the station bob like a rubber raft in a long swell, making it difficult to operate detectors that need to lock onto a particular patch of sky. The constant variation in gravitational force in different parts of the station will also cause "g-jitters" — which will affect some experiments.

Another hassle likely to be faced by instruments hung outside the station is the cloud of contamination that is expected to envelope the station. This will be produced by the station’s 33 exhaust vents, which will also spew gases and water-vapour. Instruments will thus be coated with a potentially troublesome patina. However, astronauts could periodically remove a shield protecting the earth-observing window and return it to the earth for cleaning.

Among the human problems likely to be encountered during the ISS functioning is whether there will be enough training time for the seven-member crew to operate the array of instruments they will be using. One way out is to operate experiments by remote control.

Both NASA and the Russian space agency Rosaviakosmos are under tremendous budgetary pressures, spurring new partnerships and financing agreements to fulfil plans for additional station components. The idea it to treat customers as partners rather than as contractors, for, the ultimate goal is to turn over the station to private ownership.

Repellents that kill slowly
Roopa Vajpeyi and Madhu Saxena

MOSQUITOES have been man’s unwelcome companions since time immemorial. They have been always biting men, sucking their blood and merrily flying away. It has been discovered that they are attracted towards or get distracted from certain odours and aromas, which help them to choose the person whom they wish to bite. Based on this property certain products called mosquito repellents have now been manufactured to repel them off.

Earlier, humans had learnt to cope with them using various herbal products or the innovative mosquito net. However, the urbanising process and market culture today is destroying some of the old, time-tested, safe habits. People do not use mosquito nets any more when they sleep. Products like mosquito repellents have arrived and swamped home. People have fallen for such products on account of their easy-to-use applications, without understanding what they are or what harm they can inflict through sideeffects.

Repellents are chemical compounds that are applied to exposed skin and/ or clothing or burnt or heated to produce noxious compounds. Commercial repellents come in variety of forms - sprays, coils, liquids, creams, lotions, sticks, and premoistened towelettes. Cream, lotion and stick formulations may be preferable for use on children as they offer more precise application.

Commercial formulations may contain a variety of chemicals in order to enhance the efficacy of the product and prolong the activity of the active ingredient. Repellents may also contain perfumes to conceal the odour that repels the mosquitoes.

Recently opinion has been building up against the use of mosquito repellents. Many studies have revealed that they are hazardous and produce symptoms such as nausea, anxiety, hyperflocea, diarrhoea, convulsions, bronchitis, respiratory problems, eye irritation or even fever in humans. These are on account of Pyrethroids, a class of insecticides manufactured synthetically. Under this class , Allethrin based products are included. i.e., Allethrin, d-Alletherin, d-trans-Allethrin, Pynamin, EBT, Bio-Allethrin, Eshiol, Eshiothrim, ETOC, diethyl toluimide (DEET) etc. The Pyrethoids act by attacking the nervous system of insects, provoking excitation, paralysis and death. Such chemicals are highly toxic and would be injurious to man too.

Allethrin is a strong neurotoxic insecticide that is commonly used in the mosquito coils, mats, liquid extracts or vaporisers. During the night, for a continuous period of 8 to 10 hours, smoke, vapours or fumes of Allethrin based products are being used to kill mosquitoes. As a consequence people sleeping in the room also inhale this smoke, vapours or the fumes. When inhaled for long hours continuously, these fumes may cause serious damage to our body. Effects include breast cancer, brain tumoar, and neurological and thyroid damage. Notorious Allethrin further threatens the vulnerable children and pregnant mothers. Children can develop blood cancer while foetus could be physically or mentally deformed.

Realising the side effects of such mosquito repellents, doctors have suggested that people should avoid using Allethrin based products and instead use herbal products. Considering mosquito repellents as highly risky products. Gujarat State Consumers Protection Centre had conducted a study on mosquito repellents in public interest. It has requested the Government of India - Ministry of Health and Family Welfare - to issue necessary orders to stop the manufacture and sale of mosquito repellents containing harmful insecticides.

Repellents that contain citronella, an extract from a lemon grass, Cymbopogon winterianus, are available. These products provide moderate protection against mosquito bites. A commercial, concentrated bath oil, Avon Skin-So-soft, has come into wide use as a "folk-medicine." Tests of this product indicate its repellent properties are weak and short-lived (as little as 10 to 20 minutes).

It has been suspected that some of the repellents, which are claimed to be herbal like "Tortoise Coil" may also be containing chemical compounds, and prove injurious to health.

In spite of the above facts and doubts that surrounded repellents, the consumer is facing the real dilemma to use or not to use mosquito repellants. On one hand, there are mosquitoes and malaria threatening our lives and on the other hand there are killer repellents. In India there are around 255 species of mosquitoes. These can cause diseases like malaria, dengue, filariasis, Japanese encephalitis, etc. A study conducted by the National Malaria Eradication Programme (NMEP), Delhi, reported that two million people suffer from malaria in India each year. Under such a compelling situation people perhaps are forced to die indirectly through the route of repellents.

NEW PRODUCTS & DISCOVERIES

Bridge construction can be tough, especially when people are shooting at you. That is why Titan is exceptionally useful when an army needs to hastily cross a river. Titan deploys an 80-foot-long folding bridge over a river or trench in two minutes, using hydraulics to unfold it in front of the vehicle.

The British Army has purchased 33 of the $5.6 million vehicles. These will enter action by 2005. www.vickersdefence.co.uk

Scientists have developed a process that uses bioadsorbers-adsorbers made from natural biological materials-to bind heavy metals present in waste water.

Outflows of waste water containing heavy metals are a serious hazard to nature. They result from numerous industrial processes, for example in the cleaning and coating of metal surfaces in the electroplating industry.

At the same time, these outflows are of considerable commercial value. The metals salts they contain are therefore recovered, a report in Fraunhofer Gesellschaft said.

Both thermal processes and membrane processes are employed today to filter heavy metals from waste water and return them to the production cycle. The most common method at the present time involves precipitation reactions followed by an adsorption process using synthetic-resin ion exchangers.

The new process-developed by ATEC Dr Mann GmbH in Obrigheim in collaboration with the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart-functions in the same way, but has far greater future promise.

It uses bioadsorbers-ion exchangers of regenerative raw materials. Residual products of cereal processing are used instead of synthetic resins. "Our patented process involves doping the barn with phosphate groups, enabling it to bind heavy metals," explains Dr Gunter Mann, who founded ATEC just three years ago. After regeneration with acid, they can reused a number of times-as can the purified waste water. PTI

Researchers have succeeded in integrating a high-performance solar module in the lid of a palmtop, thereby making the device completely autonomous of external electricity supply.

It is a race against time. As mobile electronic devices shrink in size and at the same time become more powerful, manufacturers of solar cells continue to raise the efficiency of their products.

There are special types where an efficiency of almost 25 per cent has been achieved-but they are still much too expensive for the mass market,a report in Fraunhofer Gesellschaft said.

However, with the successful integration of the solar module in the Casio palmtop, researchers at the Fraunhofer Institute for Solar Energy Systems ISE in freiburg have managed to find an optimum combination of these hitherto conflicting factors.

The prototype is a genuine innovation in category of devices. "The decisive factor is that the device can run on sola power alone even under low lighting levels," emphasises Dr Christopher Hebling, head of the Micro-Energy Technology group at the ISE.

"At a normal workplace, there is only three per cent of the brightness of summer sunshine. Even down to a level of one per cent, the electrical voltage provided by the solar module remains virtually constant while in conventional cell types it would have long since broken down," he said.

The high output rating of over 35 milliamps per square centimetre in direct sunlight is attributable to the solar module’s special design. PTI

Researchers are designing a new electronic guidance system for a noval 24-metre-long bus which combines the advantages of a city bus and a tram.

The new extra-long bus, Phileas, which is relatively cheap and as flexible as normal city bus will be introduced between Eindhoven and Veldhoven in 2003.

The design for the new electronic guidance system which makes the self-steering bus possible in the brainchild of the Eindhoven STW researcher in the Netherlands, Dik de Bruin.

The bus is guided by a magnetic reference system in the road surface. Every four meters, at specific locations, a permanent magnet is installed in the asphalt, a report in NWO Research Reports said.

A sensor on board the bus registers the magnetic field, determining the distance between the magnet and the sensor with an accuracy of two centimetres. The vehicle has a number of sensors in various places, meaning that the measurements overlap. This means that safety is not impaired even if one of the sensors is faulty.

The bus follows a narrow track over a pre-programmed route, steering itself around bends and automatically stopping at bus stops. It is precisely positioned close to the raised platform at the stop, which leads to a reduction in the time needed for passengers to get on and off. The average speed of the vehicle over the whole route will therefore also be higher.

Thus, all the driver has to do is regulate the speed of the vehicle and act as overall supervisor. He can also take action in case of a system failure or if anything untoward occurs. Phileas is also as fast, economical and clean as a tram, and can carry more than 200 passengers. It will run according to a precise and reliable timetable. PTI

SCIENCE QUIZ
J. P. GARG TESTS YOUR IQ

1.German chemist Robert Wilhelm Bunsen is well-known for inventing the Bunsen burner widely used in the laboratories. He also invented carbon-zinc electric cell, a photometer and a filter pump. He later developed a method of gas analysis and, along with his assistant Gustav Kirchoff, discovered two new elements. Can you name these two elements?

1. Caesium and rubidium
2. Air-Borne Contact Dermatitis
3. Ormia ochoraiea fly
4. An optical/laser beam
5. Garlic
6. Lanolin
7. Vitamins; from "vital amines"
8. Tungsten carbide
9. For measuring the rate of flow of a liquid or gas
10. Geographos.