12-01 :: January 2012

nanotimes News in Brief

DNA-based system that integrates long-range transport and information processing. They show that the path of a motor through a network of tracks containing four possible routes can be program- med using instructions that are added externally or carried by the motor itself. When external control is used they find that 87% of the motors follow the correct path, and when internal control is used 71% of the motors follow the correct path. © Nature Nanotechnology

Shelley F. J. Wickham, Jonathan Bath, Yousuke Katsuda, Masayuki Endo, Kumi Hidaka, Hiroshi Sugiyama, Andrew J. Turberfield: A DNA-based molecular motor that can navigate a network of tracks, In: Nature Nanotechnology AOP, January 22, 2012, DOI:10.1038/nnano.2011.253: http://dx.doi.org/10.1038/nnano.2011.253

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be caused by external factors, such as small impuri- ties of another material.

M. Sepioni, R. R. Nair, I.-Ling Tsai, A. K. Geim and I. V. Grigorieva: Revealing common artifacts due to fer- romagnetic inclusions in highly oriented pyrolytic gra- phite, In: Europhysics Letters, Volume 97, Number 4, February 2012, Article 47001, DOI:10.1209/0295- 5075/97/47001:

http://dx.doi.org/10.1209/0295-5075/97/47001

A research group around Irina Grigorieva found that magnetism in many commercially available graphite crystals is down to micron-sized clusters of predominantly iron that would usually be difficult to find unless the right instruments were used in a particular way. Finding the way to make graphite magnetic could be the first step to utilising it as a bio-compatible magnet for use in medicine and biology as effective biosensors. To arrive at their conclusions, the researchers firstly cut up a piece of commercially-available graphite into four sections and measured the magnetization of each piece.

Surprisingly, they found significant variations in the magnetism of each sample. It was reasonable for them to conclude that the magnetic response had to

The researchers at Wuhan University (China) and the University of Tokyo (Japan) have now deve- loped a special composite aerogel from cellulose and silicon dioxide. They begin by producing a cel- lulose gel from an alkaline urea solution. This causes the cellulose to dissolve, and to regenerate to form a nanofibrillar gel. The cellulose gel then acts as a scaffold for the silica gel prepared by a standard sol-gel process, in which a dissolved organosilicate precursor is cross-linked, gelled, and deposited onto the cellulose nanofibers. The resulting liquid-contai- ning composite gel is then dried with supercritical carbon dioxide to make an aerogel.

The novel composite aerogel demonstrates an in- teresting combination of advantageous properties: mechanical stability, flexibility, very low thermal conductivity, semitransparency, and biocompa- tibility. If required, the cellulose part can be remo- ved through combustion, leaving behind a silicon dioxide aerogel. The researchers are optimistic:

“Our new method could be a starting point for the synthesis of many new porous materials with supe-