Researchers at Boston University working with collaborators in Germany, France and Korea have developed a nanoscale torsion resonator that measures miniscule amounts of twisting or torque in a metallic nanowire. This device, the size of a speck of dust, might enable measurements of the untwisting of DNA and have applications in spintronics, fundamental physics, chemistry and biology.

Spin-induced torque is central to understanding experiments, from the measurement of angular momentum of photons to the measurement of the gyromagnetic factor of metals and a very miniaturized – about 6 microns — version of a gyroscope that measures the torques produced by electrons changing their spin states. It can be used to uncover new spin-dependent fundamental forces in particle physics, according to Raj Mohanty, Boston University Associate Professor of Physics.

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This schematic shows how a TSOM image is acquired. Using an optical microscope, several images of a 60 nanometer gold particle sample (shown in red) are taken at different focal positions and stacked together.

A technique under development at the National Institute of Standards and Technology (NIST) uses a relatively inexpensive optical microscope to quickly and cheaply analyze nanoscale dimensions with nanoscale measurement sensitivity. Termed “Through-focus Scanning Optical Microscope” (TSOM) imaging, the technique has potential applications in nanomanufacturing, semiconductor process control and biotechnology.

Optical microscopes are not widely considered for checking nanoscale (below 100 nanometers) dimensions because of the limitation imposed by wavelength of light—you can’t get a precise image with a probe three times the object’s size. NIST researcher Ravikiran Attota gets around this, paradoxically, by considering lots of “bad” (out-of-focus) images. “This imaging uses a set of blurry, out-of-focus optical images for nanometer dimensional measurement sensitivity,” he says. Instead of repeatedly focusing on a sample to acquire one best image, the new technique captures a series of images with an optical microscope at different focal positions and stacks them one on top of the other to create the TSOM image. A computer program Attota developed analyzes the image.

While Attota believes this simple technique can be used in a variety of applications, he has worked with two. The TSOM image can compare two nanoscale objects such as silicon lines on an integrated circuit. The software “subtracts” one image from the other. This enables sensitivity to dimensional differences at the nanoscale—line height, width or side-wall angle. Each type of difference generates a distinct signal.

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Environmental gains derived from the use of nanomaterials may be offset in part by the process used to manufacture them, according to research published in a special issue of the Journal of Industrial Ecology.

According to a paper by Hatice ?engül and colleagues at the University of Illinois at Chicago, strict material purity requirements, lower tolerances for defects and lower yields of manufacturing processes may lead to greater environmental burdens than those associated with conventional manufacturing.

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A research team from Osaka University has developed an ‘atomic pen’ that can inscribe nano-sized text on metal by manipulating individual atoms on the surface.

According to the researchers, the atomic pen is built on a previous discovery that silicon atoms at the tip of an atomic force microscope probe will interchange with the tin atoms in the surface of a semiconductor sample when in close proximity. Using this atom-interchange phenomenon, the researchers were able to arrange individual silicon atoms one by one on a semiconductor surface to spell out the letters ‘Si’. The writing process, which took about an hour and a half to complete, was conducted at room temperature.

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At upper right, a cadmium sulfide nanosphere before stress is applied. The hollow sphere is partly transparent to the electron beam. At lower right, the sphere after being stressed to the point of failure.

Because they are riddled with defects, bulk crystalline materials never achieve their ideal strength; nanocrystals, on the other hand, are so small there’s no room for defects. (“Nano” is short for nanometer, a billionth of a meter.) Yet while nanocrystalline materials may approach ideal strength in their resistance to stress, most nanostructures have shown only a limited ability to withstand large internal strains before they fail. Overcoming this limitation could lead to great advances in engineered materials on all scales.

Scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have used in situ transmission electron microscopy to measure hollow spherical nanoparticles that withstand extreme stress and deform without losing strength. The geometry of the novel nanospheres can be engineered to approach the theoretical ideal shear strength of the material from which they are made, in this case cadmium sulfide. The researchers report their results in the November, 2008 issue of Nature Materials, available to subscribers in advanced online publication.

“To understand what happens to the individual nanoparticles when stress is applied, you need to actually see the deformation as it is happening,” says Andrew Minor of the National Center for Electron Microscopy (NCEM) in Berkeley Lab’s Materials Sciences Division (MSD); Minor is also a member of UC Berkeley’s Department of Materials Science and Engineering (MSE). “We put the nanospheres on a flat silicon substrate inside NCEM’s In Situ Microscope sample chamber and compressed them with a flat-faced diamond punch until they fractured. Using videos of the compression tests, we could determine exactly when they fractured, and then measure the force applied at that exact moment.”

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The black portion shows a shallow pit that has “healed” on a coated sample.

Put steel under a powerful microscope, revealing its microstructure, and prepare to be surprised. Known for its strength, the metal will appear pitted and pocked.

“It is intrinsic to the material,” says Carolyn Aita, a Wisconsin Distinguished Professor at the University of Wisconsin–Milwaukee (UWM). “A pit can begin to develop from a physiochemical defect in the steel itself.”

The pitting is cause for concern for industry because it can progress and lead to corrosion. But Aita’s research can help.

In her state-of-the-art lab at the College of Engineering and Applied Science, she has developed a host of coatings that heal shallow pits and fractures on almost any material – from metal to glass to silicon. The coatings also prevent further degradation.

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A new research field called transformation optics may usher in a host of radical advances including a cloak of invisibility and ultra-powerful microscopes and computers by harnessing nanotechnology and “metamaterials.”

The field, which applies mathematical principles similar to those in Einstein’s theory of general relativity, will be described in an article to be published Friday (Oct. 17) in the journal Science. The article will appear in the magazine’s Perspectives section and was written by Vladimir Shalaev, Purdue’s Robert and Anne Burnett Professor of Electrical and Computer Engineering.

These are graphical representations of numerical simulations depicting four potential applications of a new field called transformation optics. Clockwise from top left are: a design for optical cloaking; a light "concentrator" for sensors and solar collectors; a "planar hyperlens" and "impedence-matched hyperlens" for applications including microscopes.

The list of possible breakthroughs includes a cloak of invisibility; computers and consumer electronics that use light instead of electronic signals to process information; a “planar hyperlens” that could make optical microscopes 10 times more powerful and able to see objects as small as DNA; advanced sensors; and more efficient solar collectors.

“Transformation optics is a new way of manipulating and controlling light at all distances, from the macro- to the nanoscale, and it represents a new paradigm for the science of light,” Shalaev said. “Although there were early works that helped to develop the basis for transformation optics, the field was only recently established thanks in part to papers by Sir John Pendry at the Imperial College, London, and Ulf Leonhardt at the University of St. Andrews in Scotland and their co-workers.”

Current optical technologies are limited because, for the efficient control of light, components cannot be smaller than the size of the wavelengths of light. Transformation optics sidesteps this limitation using a new class of materials, or metamaterials, which are able to guide and control light on all scales, including the scale of nanometers, or billionths of a meter.

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Scientists are using designs in nature from extreme environments to overcome the challenges of producing materials on the nanometre scale.

A team from the UK’s John Innes Centre, the Scripps Research Institute in California and the Institut Pasteur in Paris have identified a stable, modifiable virus that could be used as a nanobuilding block.

Viral nanoparticles (VNPs) are ideally sized, can be produced in large quantities, and are very stable and robust. They can self-assemble with very high precision, but are also amenable to modification by chemical means or genetic engineering.

Some applications of VNPs require them to withstand extremely harsh conditions. Uses in electrical systems may expose them to high temperatures, and biomedical uses can involve exposure to highly acidic conditions. VNPs able to remain functional in these conditions are therefore desirable. The team identified viruses from the hot acidic sulphurous springs in Iceland. One of these, SIRV2, was assessed for its suitability for use as a viral nanobuilding block.

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Scientists from the London Centre for Nanotechnology (LCN) at UCL are using a novel nanomechanical approach to investigate the workings of vancomycin, one of the few antibiotics that can be used to combat increasingly resistant infections such as MRSA.

The researchers, led by Dr Rachel McKendry and Professor Gabriel Aeppli, developed ultra-sensitive probes capable of providing new insight into how antibiotics work, paving the way for the development of more effective new drugs.

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A fresh discovery about the way water behaves inside carbon nanotubes could have implications in fields ranging from the function of ultra-tiny high-tech devices to scientists’ understanding of biological processes, according to researchers from the University of North Carolina at Chapel Hill.

The findings, published in the Oct. 3, 2008, issue of the journal, relate to a property of so-called “nano-confined” water – specifically, whether hollow carbon nanotubes take in the liquid easily or reluctantly, depending on their temperature.

As well as shedding light on the characteristics of human-made nanomaterials, researchers note that such properties are relevant to the workings of biological structures and phenomena which also function at nano-scales.

The team of scientists, led by Yue Wu, Ph.D., professor of physics in the UNC College of Arts and Sciences, examined carbon nanotubes measuring just 1.4 nanometers in diameter (one nanometer is a billionth of a meter). The seamless cylinders were made from rolled up graphene sheets, the exfoliated layer of graphite.

“Normally, graphene is hydrophobic, or ‘water hating’ – it repels water in the same way that drops of dew will roll off a lotus leaf,” said Wu. “But we found that in the extremely limited space inside these tubes, the structure of water changes, and that it’s possible to change the relationship between the graphene and the liquid to hydrophilic or ‘water-liking’.”

The UNC team did this by making the tubes colder. Using nuclear magnetic resonance – similar to the technology used in advanced medical MRI scanners – they found that at about room temperature (22 degrees centigrade), the interiors of carbon nanotubes take in water only reluctantly.

However, when the tubes were cooled to 8 degrees, water easily went inside. Wu said this shows that it is possible for water in nano-confined regions – either human-made or natural – to take on different structures and properties depending on the size of the confined region and the temperature.

Chemists at Rice University have discovered a novel method to produce ultra-pure gold nanorods - tiny, wand-like nanoparticles that are being studied in dozens of labs worldwide for applications as broad as diagnosing disease and improving electronic viewscreens.

“The content of high-aspect-ratio gold nanorods produced by today’s best synthetic methods is only about 20 percent,” said lead researcher Eugene Zubarev, assistant professor of chemistry at Rice. “A nanoparticle’s shape plays a crucial role in determining many of its physical and chemical properties, so when four out of five particles in a batch are the wrong shape, it’s a tremendous impediment to practical applications and commercialization.”
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Equations or graphs can explain what happens when atoms bump into each other, but a Purdue University researcher is hoping students will get to know how it feels using haptic, or force feedback technology.

Haptics involves the use of devices, much like joysticks, that allow the user to scan over objects or surfaces and feel the interaction forces. The device measures the position of the tip of the joystick and feeds it to a computer program containing the dimensions of virtual objects, which graphically displays the object on a 3D monitor. The program uses computer algorithms to calculate the interaction forces between the joystick tip and the virtual objects based on the object’s physical properties and feeds that sensation back to the user, just as if the person were touching the objects in real life.

One potential use for haptics is in nanotechnology, where materials are built atom-by-atom or particle-by-particle, too small for the human eye to see without the aid of a high-powered microscope. Currently, undergraduate students typically learn about nanotechnology from textbooks, and usually only graduate students are exploring nanoscale materials in the lab.

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A vial of anti-cancer nano ships glows red under a black light. The particles glow red because they contain fluorescent "quantum dot" nanoparticles.

Nanometer-sized ‘cargo-ships’ that can sail throughout the body via the bloodstream delivering anti-cancer drugs and markers into tumours that might otherwise go untreated or undetected, have been developed.

Scientists at UC San Diego, UC Santa Barbara and MIT report that their nano-cargo-ship system integrates therapeutic and diagnostic functions into a single device that avoids detection and rapid removal by the body’s natural immune system.

Michael Sailor, a professor at UC San Diego, explained: “The idea involves encapsulating imaging agents and drugs into a protective ‘mother ship’ that evades the natural processes that normally would remove these payloads if they were unprotected.

“These mother ships are only 50 nanometers in diameter, or 1,000 times smaller than the diameter of a human hair, and are equipped with an array of molecules on their surfaces that enable them to find and penetrate tumour cells in the body.”

It is hoped that eventually these microscopic cargo ships could provide the means to more effectively deliver toxic anti-cancer drugs to tumors in high concentrations without negatively impacting other parts of the body.

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