Remote Controlled Nanoscale protein motor !!

Zev Bryant, an assistant professor of bioengineering at Stanford, 

and his team are creating tiny protein motors that can be controlled remotely by light.

In every cell in your body, tiny protein motors are toiling away to keep you going. Moving muscles, dividing cells, twisting DNA – they are the workhorses of biology. But there is still uncertainty about how they function. To help biologists in the quest to know more, a team of Stanford bioengineers has designed a suite of protein motors that can be controlled remotely by light.

"Biology is full of these nanoscale machines that can perform complex tasks," said Zev Bryant, an assistant professor of bioengineering and leader of the team. "We want to understand how they can convert chemical energy into mechanical work and perform their specific tasks in cells."

Bryant's team, including doctoral student Muneaki Nakamura, designed blueprints for protein motors that would respond to light. Splicing together DNA from different organisms such as pig, slime mold and oat – the oat had the light-detecting module – the bioengineers created DNA codes for each of their protein motors.

The remote-controlled nanomotors are described by Nakamura, Bryant and their colleagues in a paper that appeared online Aug. 3 in Nature Nanotechnology.

When exposed to light, the new protein motors change direction or speed. "It's pretty fine spatial control; you can decide where the light is and where it isn't and control motors in this very exquisite way," Bryant said. Being able to control the motors in real time should be a boon for cell and developmental biologists trying to study forces and motion in living things.

"It's an entirely new project for us to be moving inside cells and organisms and to be working more closely with biologists," Bryant said. Now that he and his team have a basic blueprint, they will be able to customize these motors for biologists who are looking into specific tasks.

"In a future phase of our research, I hope that we can provide cell biologists with tools that allow them to change very specifically the properties of molecular motors in their cellular contexts," Bryant said.

There's also the possibility of using the controllable motors outside of biology, in diagnostic devices, for example. Bryant noted that researchers have worked on harnessing molecular motors to perform functions similar to their biological roles, "transporting molecules, sorting molecules, and concentrating molecules."

But first and foremost, Bryant is rebuilding these motors – incorporating features never before seen in biology – in an effort to illuminate their true nature.

"Evolution takes a basic design and makes motors that are fast and motors that are slow and motors that move long distances," Bryant said. "We've tried to build diverse motors and really challenge our understanding by pushing ourselves outside of what's already been done by evolution."

Silicon Nanorods bend light in new direction

Swirling nanorods: an axicon lens made of silicon

Ultrathin coatings that arbitrarily manipulate the phase and polarization of electromagnetic waves have been created by researchers in the US. The coatings are made from silicon nanorods using a technique that is compatible with industrial processes such as photolithography. The researchers say that the coatings could be used in new types of optical components that are much less bulky than traditional lenses. The technique could even be used to bend light in ways not possible with conventional lenses.

Fermat's principle – the rule that light travels along the path of least time – says that electromagnetic waves travel along the path on which they accumulate the least phase. In a medium of higher refractive index, the wavelength shortens and so a wave accumulates more phase across the same distance. A wave therefore bends towards the normal to reduce the distance travelled in the medium and the phase accumulated.

Manipulative metasurface

In a conventional optical component such as a lens, phase accumulates continuously as the wave propagates and this determines the nature of the wave that emerges from the lens. However, if the phase of a wave could be changed discontinuously at a surface (called a metasurface), then the wave could, in principle, be manipulated in ways not possible with conventional optics.

While this is straightforward in theory, the challenge facing physicists is how to create such a phase discontinuity using real materials. In 2011 researchers at Harvard University led by Federico Capasso and Zeno Gaburro covered a surface with V-shaped gold antennas so that the surface could be used to introduce any desired phase shift to optical waves passing through it. While this allows the arbitrary redirection of visible light, there are two major problems with this approach. First, the metallic nature of the surface means that most of the visible light is lost as it travels through the surface. Second, thin layers of metal are very difficult to work with and incompatible with the complementary metal-oxide semiconductor (CMOS) process used to make modern electronic devices.

In the new research, Mark Brongersma and colleagues at Stanford University in California use lossless silicon optical antennas. When illuminated by a particular frequency of light (which can be selected by varying its diameter), the antenna will resonate strongly. This causes the light wave to pick up a phase shift that depends on the relative orientations of its polarization axes to the antenna. By appropriately tailoring the orientations and distances between the antennas, the surface can impart any desired phase shift to the light. This allowed the researchers to reproduce the functions of a bulk lens with a single layer of nanorods just 100 nm thick.

Axicons and Bessel beams

The team was able to create various types of "lenses" using this technique. These include traditional focusing lenses and an axicon. The latter is a specialized type of conical lens that transforms an ordinary laser beam into a Bessel beam – a ring-shaped beam used in optical tweezers and eye surgery.

Optics expert John Pendry of Imperial College London is impressed. "If anyone in the electronics or photonics game wanted to use a material, it would have to be silicon," he explains. "You can lay down silicon extremely flat and shape it very precisely. Metals are nowhere near silicon in terms of the precision and the control you can exert over them; so, if you can translate a technology like metasurfaces into a silicon environment, you're on to a real winner because you can hook on to this bandwagon that's been rolling for half a century now."

I think that Intel or other companies based on CMOS technology can implement such a metasurface now

Erez Hasman, Technion-Israel

In the experiment, the metasurfaces were fabricated by electron-beam lithography, but team member Erez Hasman, now at the Technion-Israel Institute of Technology in Haifa, says that commercial companies could produce large quantities using industrial processes such as photolithography. "I think that Intel or other companies based on CMOS technology can implement such a metasurface now," he says.

"The theoretical concept is not surprising at this point, but the fact that they built it and it works is interesting," agrees Andrea Alù, an expert on metasurfaces at the University of Texas at Austin. He looks forward to the development of optical components that are not possible with normal lenses. Hasman suggests that one of the first such uses might be to interface waveguides with free space. "In general, the modes of a laser resonator or a waveguide are very complex and different from the modes of free space," he says. Coupling the two together to allow signals to pass between them, he explains, is very difficult using a lens or a prism but should be no problem using the 2D metasurface.

The research is published in Science

Power Storage in your Clothes !

Imagine being able to carry all the juice you needed to power your MP3 player, smartphone and electric car in the fabric of your jacket?

Sounds like science fiction, but it may become a reality thanks to breakthrough technology developed at a University of Central Florida research lab.

So far electrical cables are used only to transmit electricity. However, nanotechnology scientist and professor Jayan Thomas and his Ph.D. student Zenan Yu have developed a way to both transmit and store electricity in a single lightweight copper wire.

Their work is the focus of the cover story of the June 30 issue of the material science journal Advanced Materials and science magazine, Nature has published a detailed discussion about this technology in the current issue.

"It's a very interesting idea," Thomas said. "When we did it and started talking about it, everyone we talked to said, "Hmm, never thought of that. It's unique.'"

Copper wire is the starting point but eventually, Thomas said, as the technology improves, special fibers could also be developed with nanostructures to conduct and store energy.

More immediate applications could be seen in the design and development of electrical vehicles, space-launch vehicles and portable electronic devices. By being able to store and conduct energy on the same wire, heavy, space-consuming batteries could become a thing of the past. It is possible to further miniaturize the electronic devices or the space that has been previously used for batteries could be used for other purposes. In the case of launch vehicles, that could potentially lighten the load, making launches less costly, Thomas said.

So how did he get the idea about energy-storing cables? He was inspired during a routine evening walk in his neighborhood.

Thomas and his team began with a single copper wire. Then they grew a layer of nanowhiskers on the outer surface of the copper wire. These whiskers were then treated with a special alloy, which created an electrode. Two electrodes are needed for the powerful energy storage. So they had to figure out a way to create a second electrode.

They did it- this by adding a very thin plastic sheet around the whiskers and wrapping it around using a metal sheath (the second electrode) after generating nanowhiskers on it (the second electrode and outer covering). The layers were then glued together with a special gel. Because, of the insulationthe nanowhisker layer is insulating, the inner copper wire retains its ability to channel electricity, the layers around the wire independently store powerful energy.

In other words, Thomas and his team created a supercapacitor on the outside of the copper wire. Supercapcitors store powerful energy, like that needed to start a vehicle or heavy-construction equipment.

Although more work needs to be done, Thomas said the technique should be transferable to other types of materials. That could lead to specially treated clothing fibers being able to hold enough power for big tasks. For example, if flexible solar cells and these fibers were used in tandem to make a jacket, it could be used independently to power electronic gadgets and other devices.

"It's very exciting," Thomas said. "We take it step by step. I love getting to the lab everyday, and seeing what we can come up with next. Sometimes things don't work out, but even those failures teach us a lot of things. Still, I know how important getting out of the lab can be too. I won't be giving up those evening walks anytime soon. I get some great ideas during that quiet time."

Graphene and Hofstadter butterfly

Combining black and white graphene can change the electronic properties of the one-atom thick materials, University of Manchester researchers have found.

Writing in Nature Physics, a large international team led by Dr Artem Mishchenko and Sir Andre Geim from The University of Manchester shows that the electronic properties of graphene change dramatically if graphene is placed on top of boron nitride, also known as 'white graphite'.

One of the major challenges for using graphene in electronics applications is the absence of a band gap, which basically means that graphene's electrical conductivity cannot be switched off completely. Whatever researchers tried to do with the material so far, it remained highly electrically conductive.

A new direction that has recently emerged in graphene research is to try to modify graphene's electronic properties by combining it with other similar materials in multilayered stacks. This creates an additional landscape for electrons moving through graphene and, therefore, its electronic properties can change strongly.

The University of Manchester scientists have used capacitance measurements to probe these changes. They found that in combination with a magnetic field this creates numerous replicas of the original graphene spectrum. This phenomenon is known as the Hofstadter butterfly but it is the first time that well developed replica spectra have been observed.

The researchers found a wealth of unexpected physics in this new system. For example, the Hofstadter butterflies turned out to be strongly contorted, very different from the theoretical predictions. This happens because electrons feel not only the landscape but also each other, which modifies the butterfly.

Another phenomenon that the Manchester paper reports is that graphene starts behaving at very low temperatures like a tiny ferromagnet. Usually, the higher the magnetic field, the more magnetic graphene become. The Hofstadter butterfly in Manchester's capacitors leads to an unexpected oscillating behaviour of the ferromagnetism. As new replica spectra emerge and disappear, so does the ferromagnetism.