DNA Stretching

i was just surfing through some recent science and innovation updates and i found one of the most research project which is being given emphasis in many labs across world that is " Stretching of DNA". i am not a biology person so couldn't understand it much but would like to.
According to recent results

Researchers in Europe have literally unravelled a mystery that has been puzzling scientists for years: what happens to a molecule of DNA when it is stretched to its breaking point. The question is important because DNA is subjected to a range of mechanical manipulations within the cell: it can be folded, unfolded, coiled and uncoiled, unzipped and zipped up again. A detailed understanding of the elastic properties of DNA can give scientists key insights into interactions of DNA and the proteins that carry out these manipulations.

Almost two decades ago it was shown that when a molecule of double-stranded DNA is pulled from either end, it undergoes a peculiar transition. Initially the molecule resists stretching. Then, at a force of 65 piconewtons, the polymer suddenly surrenders and stretches to 1.7 times its original length with little additional force. It then becomes resistant to stretching once more.

research on strethcing of DNA from my point of view is imp may be for the study of enzymes interacting with Dna or to obtain some kind of genetic information..from 1997 research is going on this project and still scientist are working on.
here are some links for more information

http://www.rsc.org/chemistryworld/News/2009/October/19100902.asp

http://www.sciencedaily.com/releases/2006/12/061206091654.htm#

http://www.lbl.gov/Science-Articles/Archive/PBD-stretched-DNA.html

if anyone of you could understand this aspect mcuh better pls feel free to comment.
With love & peace
Abhinav

 Controlling carbon nanotubes

Nanoscopic tubes made of a lattice of carbon just a single atom deep hold promise for delivering medicines directly to a tumor, sensors so keen they detect the arrival or departure of a single electron, a replacement for costly platinum in fuel cells or as energy-saving transistors and wires.

Single-walled carbon nanotubes, made of a cheap and abundant material, have so much potential because their function changes when their atomic-level structure, referred to as chirality, changes. But for all their promise, building tubes with the right structure has proven a challenge.
A pair of Case Western Reserve University researchers mixed metals commonly used to grow nanotubes and found that the composition of the catalyst can control the chirality. In a letter published in Nature Materials, R. Mohan Sankaran, an assistant professor of chemical engineering at the Case School of Engineering, and Wei-Hung Chiang, who received his doctorate degree in chemical engineering in May, describe their findings.

"We have established a link between the structure of a catalyst and the chirality of carbon nanotubes," Sankaran said. "Change the catalyst structure by varying its composition, and you can begin to control the chirality of the nanotubes and their electrical and optical properties."

The chirality of a single-walled carbon nanotube describes how a lattice of carbon atoms is rolled into a tube. The rolling can occur at different angles, producing different structures that exhibit very different properties. Nanotubes are normally grown in bulk mixtures. When using a nickel catalyst, typically one-hird of those grown are metallic and could be used like metal wires to conduct electricity. About two-thirds are semiconducting nanotubes, which could be used as transistors, Chiang explained. But, separating them according to properties, "is costly and can damage the nanotubes." Chiang and Sankaran found that a mixed iron and nickel catalyst could change the outcome. Of the compositions tested, a catalyst of 27 percent nickel and 73 percent iron produced the most dramatic result: the vast majority of the nanotubes were semiconducting. They are now working on assessing the purity and integrating the nanotubes into thin film transistors. The authors say their findings open the door to experimenting with other elements as catalysts and different combinations, which may produce near-pure nanotubes with desired properties.



Original publication: "Linking catalyst composition to chirality distributions of as-grown single-walled carbon nanotubes by tuning NIxFe1-x nanoparticles."; Nature Material2009.