76

nanotimes News in Brief

rior properties, because it is simple and the proper- ties of the resulting aerogels can be varied widely.”

Dr. Jie Cai, Shilin Liu, Jiao Feng, Satoshi Kimura, Masahisa Wada, Prof. Dr. Shigenori Kuga, Prof. Lina Zhang: Cellulose–Silica Nanocomposite Aerogels by In Situ Formation of Silica in Cellulose Gel, In: Angewandte Chemie International Edition Early View, January 24, 2012, DOI:10.1002/anie.201105730: http://dx.doi.org/10.1002/anie.201105730

12-01 :: January 2012

It came as a complete surprise that, when the re- searchers tried the same with ordinary water, they found that it evaporates without noticing the gra- phene seal. Water molecules diffused through the graphene-oxide membranes with such a great speed that the evaporation rate was the same indepen- dently whether the container was sealed or com- pletely open.

In a report published in Science, a team led by Pro- fessor Sir Andre Geim shows that graphene-based membranes are impermeable to all gases and liquids. However, water evaporates through them as quickly as if the membranes were not there at all.

Professor Geim: “The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water.”

The University of Manchester scientists have studied membranes from a chemical derivative of graphene called graphene oxide. Graphene oxide is the same graphene sheet but it is randomly covered with other molecules such as hydroxyl groups OH-. Graphene oxide sheets stack on top of each other and form a laminate. The researchers prepared such laminates that were hundreds times thinner than a human hair but remained strong, flexible and were easy to handle. When a metal container was sealed with such a film, even the most sensitive equipment was unable to detect air or any other gas, including helium, to leak through.

R. Nair, H. Wu, P. Jayaram, V. Grigorieva and A. Geim: Unimpeded Permeation of Water Through Helium-Leak– Tight Graphene-Based Membranes, In: Science, Volume 335, Issue 6067, January 26, 2012, Pages 442-444, DOI: 10.1126/science.1211694: http://dx.doi.org/10.1126/science.1211694

Researcher at Tyndall Nati- onal Institute, Ireland, de- veloped a new nanosensor technology. The highly ad- vanced sensor technology is based on individual nanowires manufactured on a silicon chip using microelectronic fabrication techniques. The sensor technology can significantly out-perform current commercial detection devices by up to a 1,000 fold, in some cases.

http://www.tyndall.ie/users/alanoriordan

Sometimes total electrical isolation is a good thing – and that’s the idea behind a power-over-fiber