Materials Researchers: C.N.R. Rao receives Bharat Ratna Award
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Feather microstructure leads to reduced friction surfaces
T
he African darter duck is known to dive up to 35 meters without getting wet due to the microstructures of their feathers. Now, Michael Rubner, Gareth McKinley, and Robert E. Cohen from the Massachusetts Institute of Technology, Andrew Parker at the Natural History Museum, London, and their colleagues have correlated the birds’ diving behavior with the microstructures of their wings. Their goal is to apply what they learn to create friction-reducing surfaces on water-going vessels. By placing drops of different fluids on the birds’ wings, the researchers found the “contact angle” to be very high. But those experiments were carried out in the open air. When ducks are immersed in water, the microstructures on their feathers entrain tiny pockets of air, forming an air film called a “plastron” which
Materials Researchers C.N.R. Rao receives Bharat Ratna Award
C
.N.R. Rao, the Linus Pauling Research Professor and Honorary President at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, received India’s Bharat Ratna
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MRS BULLETIN
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VOLUME 39 • JULY 2014
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overall capacitance was significantly enhanced by the hybridization of conductive graphene oxide nanosheets and the LDH nanosheets. This yielded a high capacitance of up to ca. 650 farads per gram, approximately six times that of pure graphene nanosheets. The direct combination of graphene with the insulating LDH nanosheets thus resulted in an improvement in the charge-transfer efficiency. Such a superfast charging and discharging performance potentially
enables a huge energy output within a very short subsecond time scale. According to the researchers, this work would be of benefit to applications in most electronic device and hybrid cars. Additionally, Ma said they expect that this three-dimensional transition metal/ graphene hybrid approach to be effective in developing non-noble metal electrocatalysis for applications such as fuel cells. Jean. L. Njoroge
prevents water from wetting the feathers. Waterways, however, often contain an additional component: oils. Oils are known to wet bird feathers (observed as a low contact angle), which is why oil spills are particularly devastating to bird populations. Thus, before this technology can be successfully applied to ocean-going vessels, it is imperative to develop a mechanism for preventing oil from wetting the surfaces. As reported by the researchers in the July issue of the Journal of the Royal Society Interface (DOI: 10.1098/ rsif.2014.028), the key is replacement of the preening oils on feathers with a very low-energy fluorinated polymer composite, containing molecules known as fluorodecyl polyhedral oligomeric silsesquioxanes or F-POSS. The coated duck wings also allowed the researchers to study the role of just the microstructures in the feathers’ wetting behavior, essentially taking the variation of the ducks’ preening oil out of the picture. This helped them understand the important contribution of larger
scale defec
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