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Crab shell spray may help prevent malaria

A spray made from crab shells and silver nanoparticles may curb the spread of malaria-carrying mosquitoes, say scientists who tested the environment friendly solution successfully in India.

“The solution can be employed at low dosages to strongly reduce populations of the malaria vector, the Anopheles sundaicus mosquito without detrimental effects on the predation of natural mosquito enemies, such as goldfishes,” said Jiang-Shiou Hwang of the National Taiwan Ocean University. Researchers took chitosan or chitin, a non-toxic natural substance that is found in the exoskeletons of arthropods.

Researchers first crushed and oven-dried the exoskeletons of a number crabs before extracting chitin and other minerals. The subsequent creamy-white filtrate was then mixed with silver nitrate to obtain a brown-yellow solution of silver nanoparticles. The solution was sprayed over six water reservoirs at the National Institute of Communicable Disease Centre in Coimbatore.

Researchers found that even in small concentrates it killed mosquito larvae and pupa quite effectively. “This research highlighted that chitosan-fabricated silver nanoparticles are easy to produce, stable over time,” Hwang said. “It had the greatest effect during the early stages of the mosquito larvae's development,” researchers said.

Biology decides how we categorise colours

How we categorise colours is rooted in our biology and not in the language we speak, according to a new study.

Researchers analysed the response of 176 babies. Researchers looked for a phenomenon known as novelty preference - babies will look longer at a ‘new’ colour if they perceive it to be different to a familiar one.

They found that babies have five colour categories: red, yellow, green, blue and purple. While different languages have different numbers of colour categories and different locations for the boundaries between them, the common categories aligned well with the babies' categories. “The results suggest there is a biological origin to colour categories, which is later influenced by culture and environment. If you use a language that does not make a distinction between green and blue, for example, then as they grow up babies and children learn to no longer make that distinction,” said Alice Skelton, from University of Sussex.

Poor vision can lower your kid’s grades

Undetected eye problems may adversely affect your child’s ongoing learning, says scientists who found that students with poor vision had lower academic scores.

Researchers found that 30% of students tested had uncorrected eye problems that could affect their academic performances. The children referred for further optometric examination had significantly lower scores in reading, spelling, numeracy, grammar and punctuation tests. “Children’s eyes need to be tested early in primary school and throughout schooling to ensure they can fully engage with the visual aspects of classroom learning,” said researchers.

They said vision screening and assessment was not currently mandated prior to children commencing school, which may mean that some of the children will have vision and visual processing difficulties that remain undetected by parents and teachers. “The aim is to level the playing field in terms of vision and provide every opportunity for learning and academic achievement for children in school and later life,” researchers said.

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