DEFENCE scientists have developed self-luminous light devices that provide combat soldiers a fighting edge in pitch darkness and in difficult terrain. Called Beta light devices, these light sources contain no batteries nor do they de pend on electricity, but draw energy from a radioactive isotope in the form of gaseous tritium.

Scientists at the Defence Laboratory, in Jodhpur, have fabricated small borosilicate capsules, coated them with phosphor and filled them with tritium. The beta particles emitted by tritium, a radioactive isotope of hydrogen, are absorbed by the phosphor, which is excited from its ground state. Since it is unstable, it gives out energy in the form of light and then returns to its normal state.

This process of pushing up the excitation levels of phosphor, the release of light energy and its return to normal state are achieved on a continuous cycle. The Jodhpur lab designed the beta devices for specific use in the identification of crucial locat ions in black-out operations.

Some of the other applications that have been demonstrated are as a commando identification light source, convoy light device, a marker to indicate the edge of a bridge and, overall, to have an effective command and control over vehicles and safe operati ons carried out in complete darkness in strategic locations.

The gaseous tritium light devices (GTLD) typically cover a visibility range of 50-150 metres. They come in four colours -- blue, red, green and yellow, weigh 150-750 gms, depending on application, and cost Rs. 1,000-12,500.

As the main light source is a radioactive isotope, the safety aspects have to be taken into consideration before designing a beta device. The main users of these products are the Defence forces. The Jodhpur laboratory has designed protocols and special e nvironmental stress tests for these products.



SPIC kit to detect infection in bananas

THE presence of tissue-cultured products is on the increase in the supermarkets. Bananas and a range of ornamental flowers are among the most prominent, and a significant quantity of such produced is being exported. But during the last two years, tissue- cultured bananas have been affected by a disease caused by a virus named bunchy-top virus.

The result is the stunted growth of the plant, and the quality of the banana fruit too is affected. Export samples affected by the virus were rejected, leading to sizeable loss to the growers.

The Centre for Biotechnology, of the SPIC Science Foundation, has developed a low-cost diagnostic kit that can detect the viral infection in apparently healthy plants which do not outwardly show symptoms of the disease.

The kit is useful in indexing the banana tissues before clonal propagation in the tissue culture industry. It can emerge as a sound alternative to the routinely-used ELISA test.

According to SPIC, the kit helps monitor the health status of the banana plants at any point of time. The test, based on the commonly used polymerase chain reaction (PCR) technique, does not, however, offer protection from the dreaded banana bunchy top v irus.

To conduct the test, all that is required is about 100 mg of the banana leaf, or a sample of the plant tissue of at least 5 cm in size, properly placed in a bag, labelled and sealed for the experiment. The test takes less than 48 hours to get accurate, f ully documented results.

In the evolving tissue culture markets, the testing and quality of products, especially fruits, spices and flowers, have become critical. The diagnostic kit developed by SPIC is one of the handful of products indigenously produced as a result of biotechn ology research that would benefit the tissue culture industry.

The use of the product needs training, and is not tailor-made for farmers. In that context, the practical application of the kit would be that small farmers and entrepreneurs involved in the tissue culture industry could send samples for testing. The Department of Biotechnology (DBT) and the Indian Agriculture Research Institute (IARI) are in the process of setting up a national virus testing facility on similar lines.



Hardness tester from CSIO

THE Central Scientific Instrumentation Organisation (CSIO), Chandigarh, a constituent laboratory of the Council for Scientific and Industrial Research (CSIR), has developed a micro-hardness tester for metals, alloys, thin wires and sheets.

The low-cost opto-mechanical system can be used for measuring the microscopic hardness of a range of materials as well as the micro-constituents present in a metal matrix, and case depth of nitrided components.

The fine measurement of the thickness of the material used in various products will help in improvement of the quality as well as the use of high-quality components.

The CSIO-developed hardness tester is based on the pressure exerted by a diamond indenter -- a square-based pyramid with an angle of 136 degrees -- on the specimen under investigation.

The system consists of a micrometer eye-piece, a loading and unloading mechanism attached to a microscope for taking the indentation of the diamond indentator on the surface of the specimen under certain load, an illumination system and a precision revol ving table.

A prototype of the system has been put through testing and calibration. Based on the feedback from it, an improved version has also been fabricated by the CSIO. The Department of Science and Technology (DST) has funded the project, which promises to brin g a new product to the market in the near future.

Hardness-testing devices are manufactured in India by very few firms. A small and medium enterprise in Mumbai, called Blue Steel, fabricates world-class rubber hardness testers and exports them to several European countries.






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