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Scientists in Hyderabad have developed a supercapacitor, a device that stores electrical charge. The charge that a capacitor can hold — capacitance — depends upon the surface area of electrodes. Lead scientists Dr Tata Narasinga Rao and Dr S Anandan at ARCI (International Advanced Research Centre for Powder Metallurgy and New Materials) increased the surface area by ‘roughening’ the electrodes — ribbons of aluminium foil — with a coat of nano carbon powder, derived from petcoke, an oil refinery waste. Instead of the dielectric (insulator), they used an electrolyte (tetraethylammonium tetrafluoroborate). The capacitance they achieved — 1,198 Farads — is high and they want to scale it up further to 3,000 F — the level achieved by the US company Maxwell — which would put it on a par with the best in the world. The Hyderabad scientists used petcoke because of its high yield of carbon. Besides, petcoke is a sulphurous refinery waste; employing it will help with its disposal.
Capacitors, like batteries, are energy storage devices, but since they pick up charge rapidly, and discharge swiftly, they have applications which are different from — as well as complementary to — batteries. For example, they can be used in regenerative braking, where the kinetic energy lost during braking is captured and put into a storage device.
Dr Narasinga Rao said the technology was quite mature. “In January, we will show a bicycle powered by a supercapacitor,” he said. The ARCI is ready to offer the technology to industry.
Not true colours
Scientists at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, have produced artificial colours by coating titanium dioxide (TiO2) on titanium sputtered (hard or flexible) substrates. This ‘structural colouring’ mimics nature — this is how peacock feathers, butterfly wings and gem opals get their colours. Scientists S Angappane and Gaurav Shukla fabricated structural colours artificially by depositing nanorods and thin films of TiO2 on hard and flexible substrates using a technique known as ‘glancing angle deposition’. The CeNS team showed that the colours could be manipulated by varying the thickness and refractive index of the TiO2 layer, and how to get an entire range of colours, from blue to red. This system works for glass, PET flexible and ceramic substrates, but the scientists said the coating could be done on any flat surface, including fabrics.
Healer from spirulina
An injectable hydrogel derived from spirulina can heal internal injuries — a development that may particularly help diabetes patients.
Scientists at the Institute of Nano Science and Technology (INST), Mohali, added kappa-carrageenan, a water-soluble polysaccharide (sugars in polymerised form) from red seaweeds, and a pigmented protein called C-phycocyanin, found in spirulina, to come up with the healing hydrogel. K-carrageenan brings in gelling properties, while C-phycocyanin helps heal the wound.
The hydrogel will be highly beneficial for people of all age groups in wound healing applications.
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