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What's New in Nanotechnology?

March 27, 2014

NanoDays is organized by the Nanoscale Informal Science Education Network (NISE Net), and takes place nationally from March 29 - April 6, 2014. This community-based event is the largest public outreach effort in nanoscale informal science education and involves science museums, research centers, and universities from Puerto Rico to Alaska. NanoDays celebrations bring university researchers together with science educators to create new and unique learning experiences for both children and adults to explore the miniscule world of atoms, molecules, and nanoscale forces. Most NanoDays events combine fun hands-on activities with presentations on current research. A range of exciting NanoDays programs demonstrate the special and unexpected properties found at the nanoscale, examine tools used by nanoscientists, showcase nano materials with spectacular promise, and invite discussion of technology and society.  

March 20, 2014

Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions – air, argon, nitrogen and a vacuum – to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Image Credit: Kono Lab/Rice University)

On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research. While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity. A series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass. That, said the researchers, makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor, like aerospace applications. Present-day transmission cables made of copper or aluminum are heavy because their low tensile strength requires steel-core reinforcement. Scientists working with nanoscale materials have long thought there’s a better way to move electricity from here to there. Certain types of carbon nanotubes can carry far more electricity than copper. The ideal cable would be made of long metallic “armchair” nanotubes that would transmit current over great distances with negligible loss, but such a cable is not feasible because it’s not yet possible to manufacture pure armchairs in bulk, Rice professor Matteo Pasquali said. In the meantime, the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper. The cable developed is strong and flexible even though at 20 microns wide, it’s thinner than a human hair.

March 13, 2014

Todd Rider prepares DRACO antiviral therapeutics at Draper Laboratory.Image Credit: Draper Laboratory

Newly emerging flu viruses could soon be countered by a treatment that Draper Laboratory is developing that “traps” viruses before they can infect host cells. Further into the future, patients suffering from any type of virus could be cured with DRACO, a drug also under development at Draper that is designed to rapidly recognize and eliminate cells infected by virtually any virus. Both methods could help safeguard against bioterrorist attacks and naturally occurring pandemics in a manner that is unlikely to lead to treatment-resistant strains. Initial testing on the treatments, which each use tiny, non-toxic particles that can be injected, inhaled, or eaten, has shown them to be effective and safe against a multitude of strains of disease Nanotraps, which could be taken at the first sign of infection or exposure, is likely the first of the products ready for use, and is expected to begin clinical trials in two to five years, according to Jim Comolli, who leads the research on the effort at Draper. Nanotraps, developed by a team of researchers from Draper, MIT, the University of Massachusetts Medical School, and the University of Santa Barbara, are nanoparticles that act as viral “traps” using specific molecules found naturally within the human body. The nanotraps look like the surface of a cell, with numerous carbohydrate molecules attached that closely resemble those targeted by flu viruses in the human respiratory system. These molecules, initially characterized in the Sasisekharan Lab at MIT, act as bait for the flu virus, which bind to the nanotrap instead of a host cell and are cleared away with mucus, preventing infection, Comolli said.

March 06, 2014

This image shows a collection of vaccinating nanoparticles, which at their largest are about 1,000 times smaller than a human hair. The inset graphic is a representation of how the engineered proteins decorate a nanoparticle’s surface.Image Credit: University of Washington

Vaccines combat diseases and protect populations from outbreaks, but the life-saving technology leaves room for improvement. Vaccines usually are made en masse in centralized locations far removed from where they will be used. They are expensive to ship and keep refrigerated and they tend to have short shelf lives. University of Washington engineers hope a new type of vaccine they have shown to work in mice will one day make it cheaper and easy to manufacture on-demand vaccines for humans. Immunizations could be administered within minutes where and when a disease is breaking out. “We’re really excited about this technology because it makes it possible to produce a vaccine on the spot. For instance, a field doctor could see the beginnings of an epidemic, make vaccine doses right away, and blanket vaccinate the entire population in the affected area to prevent the spread of an epidemic,” said François Baneyx, a UW professor of chemical engineering.  The UW team injected mice with nanoparticles synthesized using an engineered protein that both mimics the effect of an infection and binds to calcium phosphate, the inorganic compound found in teeth and bones. After eight months, mice that contracted the disease made threefold the number of protective “killer” T-cells – a sign of a long-lasting immune response – compared with mice that had received the protein but no calcium phosphate nanoparticles. The nanoparticles appear to work by ferrying the protein to the lymph nodes where they have a higher chance of meeting dendritic cells, a type of immune cell that is scarce in the skin and muscles, but plays a key role in activating strong immune responses.

February 27, 2014

Hydrogen bubbles as they appear in a photoelectrochemical cell.Image Credit: © LPI / EPFL

Water and some nano-structured iron oxide is all it takes to produce bubbles of solar hydrogen. École Polytechnique Fédérale de Lausanne (EPFL) and Technion scientists just discovered the champion structure to achieve this! In the quest for the production of renewable and clean energy, photoelectrochemical cells (PECs) constitute a sort of a Holy Grail. PECs are devices able of splitting water molecules into hydrogen and oxygen in a single operation, thanks to solar radiation. "As a matter of fact, we've already discovered this precious chalice, says Michael Grätzel, Director of the Laboratory of Photonics and Interfaces (LPI) at EPFL and inventor of dye-sensitized photoelectrochemical cells. We have just reached an important milestone on the path that will lead us forward to profitable industrial applications." EPFL researchers, working with Avner Rotschild from Technion (Israel), have managed to accurately characterize the iron oxide nanostructures to be used in order to produce hydrogen at the lowest possible cost. "The whole point of our approach is to use an exceptionally abundant, stable and cheap material: rust," adds Scott C. Warren. At the end of last year, Kevin Sivula, one of the collaborators at the LPI laboratory, presented a prototype electrode based on the same principle. Its efficiency was such that gas bubbles emerged as soon as it was under a light stimulus. Without a doubt, the potential of such cheap electrodes was demonstrated, even if there was still room for improvement By using transmission electron microscopy (TEM) techniques, researchers were able to precisely characterize the movement of the electrons through the cauliflower-looking nanostructures forming the iron oxide particles, laid on electrodes during the manufacturing process. "These measures have helped us understand the reason why we get performance differences depending on the electrodes manufacturing process", says Grätzel.

Categories : University News
February 20, 2014

Engineers have created a new light-reactive material made up of carbon nanotubes and plastic polycarbonate. This video demonstrates experimental “curtains” that are engineered to either open or close in response to light. (Video Source: UC Berkeley; Video courtesy of Javey Research Group)

Forget remote-controlled curtains. A new development by researchers at the University of California, Berkeley, could lead to curtains and other materials that move in response to light, no batteries needed.  A research team led by Ali Javey, associate professor of electrical engineering and computer sciences, layered carbon nanotubes – atom-thick rolls of carbon – onto a plastic polycarbonate membrane to create a material that moves quickly in response to light. Within fractions of a second, the nanotubes absorb light, convert it into heat and transfer the heat to the polycarbonate membrane’s surface. The plastic expands in response to the heat, while the nanotube layer does not, causing the two-layered material to bend. “The advantage of this new class of photo-reactive actuator is that it is very easy to make, and it is very sensitive to low-intensity light,” said Javey, who is also a faculty scientist at the Lawrence Berkeley National Lab. “The light from a flashlight is enough to generate a response.” The researchers were able to tweak the size and chirality – referring to the left or right direction of twist – of the nanotubes to make the material react to different wavelengths of light. The swaths of material they created, dubbed “smart curtains,” could bend or straighten in response to the flick of a light switch. “We envision these in future smart, energy-efficient buildings,” said Javey. “Curtains made of this material could automatically open or close during the day.”  Other potential applications include light-driven motors and robotics that move toward or away from light, the researchers said.

 

Categories : University News
February 13, 2014

ORNL and UT researchers have invented a method to merge different 2-dimensional materials into a seamless layer. This colorized scanning tunneling microscope image shows a single-atom sheet composed of graphene (seen in blue) combined with hexagonal boron nitride (seen in yellow).Image Credit: Oak Ridge National Laboratory

Researchers at the Department of Energy’s Oak Ridge National Laboratory and the University of Tennessee, Knoxville have pioneered a new technique for forming a two-dimensional, single-atom sheet of two different materials with a seamless boundary. The study could enable the use of new types of 2-D hybrid materials in technological applications and fundamental research. By rethinking a traditional method of growing materials, the researchers combined two compounds -- graphene and boron nitride -- into a single layer only one atom thick. Graphene, which consists of carbon atoms arranged in hexagonal, honeycomb-like rings, has attracted waves of attention because of its high strength and electronic properties. “People call graphene a wonder material that could revolutionize the landscape of nanotechnology and electronics,” ORNL’s An-Ping Li said. “Indeed, graphene has a lot of potential, but it has limits. To make use of graphene in applications or devices, we need to integrate graphene with other materials.” The researchers first grew graphene on a copper foil, etched the graphene to create clean edges, and then grew boron nitride through chemical vapor deposition. Instead of conforming to the structure of the copper base layer as in conventional epitaxy, the boron nitride atoms took on the crystallography of the graphene.

February 06, 2014

This wafer contains tiny computers using carbon nanotubes, a material that could lead to smaller, more energy-efficient processors.Image Source: Stanford University; Photo Credit: Norbert von der Groeben)

A team of Stanford University engineers has built a basic computer using carbon nanotubes, a semiconductor material that has the potential to launch a new generation of electronic devices that run faster, while using less energy, than those made from silicon chips. This unprecedented feat culminates years of efforts by scientists around the world to harness this promising but quirky material. The research was led by Stanford professors Subhasish Mitra and H.-S. Philip Wong. "People have been talking about a new era of carbon nanotube electronics moving beyond silicon," said Mitra, an electrical engineer and computer scientist. "But there have been few demonstrations of complete digital systems using this exciting technology. Here is the proof." Experts say the Stanford achievement will galvanize efforts to find successors to silicon chips, which could soon encounter physical limits that might prevent them from delivering smaller, faster, cheaper electronic devices. "Carbon nanotubes [CNTs] have long been considered as a potential successor to the silicon transistor," said Professor Jan Rabaey, a world expert on electronic circuits and systems at the University of California-Berkeley. But until now it hasn't been clear that CNTs could fulfill those expectations. "There is no question that this will get the attention of researchers in the semiconductor community and entice them to explore how this technology can lead to smaller, more energy-efficient processors in the next decade," Rabaey said.

Categories : University News
January 30, 2014

Roy’s team used an imprinting technology that works like a cookie cutter but on the nanoscale. Drugs are mixed with a polymer solution and dispensed on a silicon wafer. Then a shape is imprinted onto the polymer-drug mixture using a quartz template. The material is then solidified using UV light. Whatever the cookie cutter’s template – triangle, rod, disc – a nanoparticle with that shape is produced.Image Source: Georgia Tech, Image Credit: Rob Felt

For years scientists have been working to fundamentally understand how nanoparticles move throughout the human body. One big unanswered question is how the shape of nanoparticles affects their entry into cells. Now researchers have discovered that under typical culture conditions, mammalian cells prefer disc-shaped nanoparticles over those shaped like rods. Understanding how the shape of nanoparticles affects their transport into cells could be a major boost for the field of nanomedicine by helping scientists to design better therapies for various diseases, such as improving the efficacy and reducing side effects of cancer drugs. In addition to nanoparticle geometry, the researchers also discovered that different types of cells have different mechanisms to pull in nanoparticles of different sizes, which was previously unknown. The research team also used theoretical models to identify the physical parameters that cells use when taking in nanoparticles. “This research identified some very novel yet fundamental aspects in which cells interact with the shape of nanoparticles,” said Krishnendu Roy of Department of Biomedical Engineering at Georgia Tech and Emory University. He conducted this research at The University of Texas at Austin in collaboration with Profs. S. V. Sreenivasan and Li Shi, but is continuing the work at Georgia Tech. Roy’s team used a unique approach to making the differently shaped nanoparticles. The researchers adapted an imprinting technology used in the semiconductor industry and rigged it to work with biological molecules, Roy said. This imprinting technique, which they developed at UT-Austin, works like a cookie cutter but on the nanoscale. Drugs are mixed with a polymer solution and dispensed on a silicon wafer. Then a shape is imprinted onto the polymer-drug mixture using a quartz template. The material is then solidified using UV light. Whatever the cookie cutter’s template – triangle, rod, disc – a nanoparticle with that shape is produced.

January 23, 2014

An electron microscope image (left) shows a faceted single crystal consisting of nanoparticles brought together using DNA interactions. A schematic (right) illustrates how the lattice of nanoparticles is held together by DNA, taken from a simulation used to model the system. The observed crystal shape is a rhombic dodecahedron, a 12-sided polyhedron made up of congruent rhombic faces.Image Credit: Northwestern University

Nature builds flawless diamonds, sapphires and other gems. Now a Northwestern University research team is the first to build near-perfect single crystals out of nanoparticles and DNA, using the same structure favored by nature. “Single crystals are the backbone of many things we rely on -- diamonds for beauty as well as industrial applications, sapphires for lasers and silicon for electronics,” said nanoscientist Chad A. Mirkin. “The precise placement of atoms within a well-defined lattice defines these high-quality crystals. “Now we can do the same with nanomaterials and DNA, the blueprint of life,” Mirkin said. “Our method could lead to novel technologies and even enable new industries, much as the ability to grow silicon in perfect crystalline arrangements made possible the multibillion-dollar semiconductor industry.” His research group developed the “recipe” for using nanomaterials as atoms, DNA as bonds and a little heat to form tiny crystals. This single-crystal recipe builds on superlattice techniques Mirkin’s lab has been developing for nearly two decades. In this recent work, Mirkin, an experimentalist, teamed up with Monica Olvera de la Cruz, a theoretician, to evaluate the new technique and develop an understanding of it. Given a set of nanoparticles and a specific type of DNA, Olvera de la Cruz showed they can accurately predict the 3-D structure, or crystal shape, into which the disordered components will self-assemble.

Categories : University News

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