Friday, December 27, 2024
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Cheap 'nano-tablet' purifies water

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RESEARCHERS HAVE developed a water purification tablet comprised of nanoparticles that can be used by developing world communities with no access to clean water. The tablet, MadiDrop, invented by PureMadi — a non-profit organisation of the University of Virginia, United States — was presented at the organisation’s one-year celebration event earlier this month. It consists of a small ceramic disk filled with silver or copper nanoparticles that is placed a water vessel, where it can repeatedly disinfect water for up to six months. “There is nothing easier,” James Smith, a professor in the Environmental and Water Resources programme at the University of Virginia who co-leads the PureMadi project says. “You drop it in your water container, fill the container up at night and the water will be safe to drink for all the next day.” The tablet is capable of treating 20 litres of water per day. Only trace amounts of silver and copper nanoparticles are released into the water — at levels that are safe for human consumption, but high enough to kill waterborne pathogenic micro-organisms, says Smith. The tool developed for use in communities without safe drinking water is named ‘Madi’ after the Tshivenda (one of the official languages of South Africa) word for water. Smith says there isneed for more long-term field tests on the tablet’s life span. “Based on shorter-term tests that we can extrapolate, it should work for six months,” he says. “We will be conducting longer-term tests in South Africa in June, July, and August.” It is hoped that the tablet will improve the supply of safe water to the community of Mashamba in South Africa and beyond, says John Mudau, director of the Centre for Rural Development and Poverty Alleviation at the University of Venda, South Africa. The university is ensuring that the tablet complies with South African safety standards; that education on water quality reaches the rural communities of Limpopo province that have little or no access to clean water; and that locals accept the tablet. The process is technically viable, saysAnthonyTurton, a water and environment expert in the Centre for Environmental Management at the University of Free State, South Africa. However, he warns that the filter’s sustainability is predicated on a number of factors including cost and social acceptability. PureMadi established a water filter factory in Limpopo province, South Africa last year, employing local workers who have already produced several hundred alternative flowerpot-like water filters. This means that it is likely to attract support from other companies eager to demonstrate their commitment to sustainability and regional development, Turton adds. The additional value of the tablet lies in the way it provides a transfer of skills through usage of cheap local materials and the employment of local people from deeply impoverished communities to produce these gadgets, he says. Smith is uncertain as to how much the tablet will cost. But he adds: “If we can obtain a price point of US$5, it would likely be the least-expensive or among the least expensive point-of-use water purification methods available on the market”. (SciDev)

 

Mobile phone microscope detects worm infections

 

CHILDREN SUFFERING from intestinal worms can now be diagnosed using a mobile phone microscope that is significantly cheaper than conventional methods, which are prohibitively expensive for many communities. The microscope costs around US$15 and runs off the phone’s battery, whereas a conventional light microscope costs US$200 and requires electricity in most countries. To build the microscope, scientists transformed an iPhone 4S mobile phone into a microscope by temporarily mounting a 3-millimetre ball lens to the camera, using double-sided tape to hold it firmly. A US$8 ball lens was positioned in a small hole punctured in the middle of the double-sided tape. They then placed the mobile phone microscope on top of the slide, which was illuminated from below by a small flashlight. Images were viewed on the mobile phone screen, and magnification of up to 60 times was enabled using the digital zoom function. Scientists from Canada, Switzerland, Tanzania and United States, used the microscope to evaluate stool samples from almost 200 children in Pemba, Tanzania, alongside conventional light microscope to measure the efficacy of different intestinal worm treatments. A study published in the American Journal of Tropical Medicine and Hygiene reports that the accuracy of the mobile phone microscope varies depending on the worm type and infection intensity. The microscope was found to detect 69.4 per cent of helminth eggs, 81 per cent of giant roundworm infections and 14 per cent of all hookworm infections. “It is 70 per cent accurate but we think it can be up to 90 per cent,” says Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, Canada, and the study’s lead author. The study reports that the microscope will only be of clinical standard when it is sensitive enough to detect 80 per cent of infections. “It was quite successful at detecting moderate to heavy infections but not very good at detecting mild infections where there might be only a few eggs in the sample,” Bogoch adds. However, the researchers are confident the technology could be a valuable and popular tool for regions where intestinal worm infestation is widespread, due to it being easy to make, portable and cheap. The new application is also potentially relevant in the diagnosis of other infections in the blood, urine and intestine, says Bogoch, and could work equally well with other types of phones with camera zooms. David Walker, president of the American Society of Tropical Medicine and Hygiene, says: “This study is an illustration of how a modest investment in tropical disease research can help reap enormous health benefits for children.” Jennifer Atim, a data specialist at Health Alert-Uganda, says the innovation is another tool for improving child health, but wonders whether it will be available since many information and communication technology related innovations fail to make the transition from lab to field in Africa. Intestinal worms can hinder physical and mental development in children by causing chronic anaemia and malnutrition, but when diagnosed early can be treated successfully with cheap drugs.

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