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What's New in Nanotechnology?

June 27, 2012

The honeycomb material structure allows selective adsorption of carbon dioxide while allowing other gases such as nitrogen, methane, and hydrogen to pass back through. (Image Credit: University of Nottingham)

A novel porous material that has unique carbon dioxide retention properties has been developed through research led by The University of Nottingham in the UK. The findings form part of ongoing efforts to develop new materials for gas storage applications and could have an impact in the advancement of new carbon capture products for reducing emissions from fossil fuel processes. It focuses on the metal organic framework NOTT-202a, which has a unique honeycomb-like structural arrangement and can be considered to represent an entirely new class of porous material. Most importantly, the material structure allows selective adsorption of carbon dioxide — while other gases such as nitrogen, methane and hydrogen can pass back through, the carbon dioxide remains trapped in the materials nanopores, even at low temperatures. NOTT-202a consists of a tetra-carboxylate ligands — a honeycomb like structure made of a series of molecules or ions bound to a central metal atom — and filled with indium metal centres. This forms a novel structure consisting of two interlocked frameworks. State-of-the-art X-ray powder diffraction measurements at Diamond Light Source and advanced computer modelling were used to probe and gain insight into the unique carbon dioxide capturing properties of the material.

Categories : University News
May 17, 2012

Vienna Printer Distance between the towers: 90 µm (credit: Klaus Cicha). Photo courtesy Vienna University of Technolog

Printing three dimensional objects with incredibly fine details is now possible using “two-photon lithography”. With this technology, tiny structures on a nanometer scale can be fabricated. Researchers at theVienna University of Technology (TU Vienna) have now made a major breakthrough in speeding up this printing technique: The high-precision-3D-printer at TU Vienna is orders of magnitude faster than similar devices. This opens up completely new areas of application, such as in medicine. The 3D printer uses a liquid resin, which is hardened at precisely the correct spots by a focused laser beam. The focal point of the laser beam is guided through the resin by movable mirrors and leaves behind a polymerized line of solid polymer, just a few hundred nanometers wide. This high resolution enables the creation of intricately structured sculptures as tiny as a grain of sand. “Until now, this technique used to be quite slow”, says Professor Jürgen Stampfl from the Institute of Materials Science and Technology at the TU Vienna. “The printing speed used to be measured in millimeters per second – our device can do five meters in one second.” In two-photon lithography, this is a world record. Researchers all over the world are working on 3D printers today – at universities as well as in industry. “Our competitive edge here at the Vienna University of Technology comes from the fact that we have experts from very different fields, working on different parts of the problem, at one single university”, Jürgen Stampfl emphasizes. In materials science, process engineering or the optimization of light sources, there are experts working together and coming up with mutually stimulating ideas. Because of the dramatically increased speed, much larger objects can now be created in a given period of time. This makes two-photon-lithography an interesting technique for industry. At the TU Vienna, scientists are now developing bio-compatible resins for medical applications. They can be used to create scaffolds to which living cells can attach themselves facilitating the systematic creation of biological tissues. The 3d printer could also be used to create tailor made construction parts for biomedical technology or nanotechnology.

Categories : University News
May 04, 2012

The University of Texas at Tyler has created a student chapter of the Institute of Electrical and Electronics Engineers, Dr. Harold Doty, College of Business and Technology dean, announced. The UT Tyler IEEE Nanotechnology Student Branch Chapter is the first of its kind in Texas and only the second one worldwide. "I wanted to create an interest in nanotechnology for students in the industrial technology program. The chapter is a perfect platform to get students involved,” said Dr. Dominick Fazarro, UT Tyler associate professor and chapter adviser. “Nanotechnology is considered the new industrial revolution, and students need to know the future implications and impact in society.” Nanotechnology is the engineering science of creating materials at the atomic and molecular level. It has many applications in a variety of industries including medicine, energy, electronics and computers. One of the 15 campuses of the UT System, UT Tyler offers excellence in teaching, research, artistic performance and community service. More than 80 undergraduate and graduate degree programs are available at UT Tyler, which has an enrollment of almost 7,000 high-ability students at its campuses in Tyler, Longview and Palestine.

Categories : University News
April 25, 2012

Gold nanoparticles created by the Rice University lab of Eugene Zubarev take on the shape of starfruit in a chemical bath with silver nitrate, ascorbic acid and gold chloride. Photo courtesy Zubarev Lab/Rice University

They look like fruit, and indeed the nanoscale stars of new research at Rice University have tasty implications for medical imaging and chemical sensing.  Starfruit-shaped gold nanorods synthesized by chemist Eugene Zubarev and Leonid Vigderman, a graduate student in his lab at Rice’s BioScience Research Collaborative, could nourish applications that rely on surface-enhanced Raman spectroscopy (SERS). The researchers found their particles returned signals 25 times stronger than similar nanorods with smooth surfaces. That may ultimately make it possible to detect very small amounts of such organic molecules as DNA and biomarkers, found in bodily fluids, for particular diseases. “There’s a great deal of interest in sensing applications,” said Zubarev, an associate professor of chemistry. “SERS takes advantage of the ability of gold to enhance electromagnetic fields locally. Fields will concentrate at specific defects, like the sharp edges of our nanostarfruits, and that could help detect the presence of organic molecules at very low concentration.” SERS can detect organic molecules by themselves, but the presence of a gold surface greatly enhances the effect, Zubarev said. “If we take the spectrum of organic molecules in solution and compare it to when they are adsorbed on a gold particle, the difference can be millions of times,” he said. The potential to further boost that stronger signal by a factor of 25 is significant, he said. Zubarev and Vigderman grew batches of the star-shaped rods in a chemical bath. They started with seed particles of highly purified gold nanorods with pentagonal cross-sections developed by Zubarev’s lab in 2008 and added them to a mixture of silver nitrate, ascorbic acid and gold chloride.

Categories : University News
April 08, 2012

This illustration shows lithium atoms (red) adhered to a graphene lattice that will produce electricity when bent, squeezed or twisted. Conversely, the graphene will deform when an electric field is applied, opening new possibilities in nanotechnology. (Image Credit: Mitchell Ong / Stanford School of Engineering)

To the long list of exceptional physical properties of graphene, engineers atStanford Universityhave added yet another: piezoelectricity, the property of some materials to produce an electric charge when bent, squeezed or twisted. In what became known as the "Scotch tape technique," researchers first extracted graphene with a piece of adhesive in 2004. Graphene is a single layer of carbon atoms arranged in a honeycomb, hexagonal pattern. Under a microscope, it looks like chicken wire.  In 2010, the researchers who first isolated it shared the Nobel Prize. Graphene is a wonder material. It is a hundred times better at conducting electricity than silicon. It is stronger than diamond. And, at just one atom thick, it is so thin as to be essentially a two-dimensional material. Such promising physics have made graphene the most studied substance of the last decade, particularly in nanotechnology. Yet, while graphene is many things, it is not piezoelectric. Perhaps most valuably, piezoelectricity is reversible. When an electric field is applied, piezoelectric materials change shape, yielding a remarkable level of engineering control. Piezoelectrics have found application in countless devices from watches, radios and ultrasound to the push-button starters on propane grills, but these uses all require relatively large, three-dimensional quantities of piezoelectric materials. The Stanford team's engineered graphene has, for the first time, extended such fine physical control to the nanoscale. "The physical deformations we can create are directly proportional to the electrical field applied and this represents a fundamentally new way to control electronics at the nanoscale," said Evan Reed, head of the Materials Computation and Theory Group at Stanford. "This phenomenon brings new dimension to the concept of  'straintronics' for the way the electrical field strains — or deforms — the lattice of carbon, causing it to change shape in predictable ways." "Piezoelectric graphene could provide an unparalleled degree of electrical, optical or mechanical control for applications ranging from touchscreens to nanoscale transistors," said Mitchell Ong, a post-doctoral scholar in Reed's lab. Using a sophisticated modeling application running on high-performance supercomputers, the engineers simulated the deposition of atoms on one side of a graphene lattice – a process known as doping – and measured the piezoelectric effect. They modeled graphene doped with lithium, hydrogen, potassium and fluorine, as well as combinations of hydrogen and fluorine and lithium and fluorine, on either side of the lattice. Doping just one side of the graphene, or doping both sides with different atoms, is key to the process as it breaks graphene's perfect physical symmetry, which otherwise cancels the piezoelectric effect. The results surprised both engineers. "We thought the piezoelectric effect would be present, but relatively small. Yet, we were able to achieve piezoelectric levels comparable to traditional three-dimensional materials," said Reed. "It was pretty significant."

Categories : University News
March 25, 2012

In this graphic, clockwise from top: the glue can be printed in a pattern on a surface, treated to make it sticky (red) and then a new layer stuck on top. The background is a patterned nanoglue on a surface.(Tingrui Pan/UC Davis photo)

Engineers at the University of California, Davis, have invented a superthin “nanoglue” that could be used in new-generation microchip fabrication. “The material itself (say, semiconductor wafers) would break before the glue peels off,” said Tingrui Pan, professor of biomedical engineering. He and his fellow researchers have filed a provisional patent. Conventional glues form a thick layer between two surfaces. Pan’s nanoglue, which conducts heat and can be printed, or applied, in patterns, forms a layer the thickness of only a few molecules. The nanoglue is based on a transparent, flexible material called polydimethylsiloxane, or PDMS, which, when peeled off a smooth surface usually leaves behind an ultrathin, sticky residue that researchers had mostly regarded as a nuisance. Pan and his colleagues realized that this residue could instead be used as glue, and enhanced its bonding properties by treating the residue surface with oxygen. The nanoglue could be used to stick silicon wafers into a stack to make new types of multilayered computer chips. Pan said he thinks it could also be used for home applications — for example, as double-sided tape or for sticking objects to tiles. The glue only works on smooth surfaces and can be removed with heat treatment.

Categories : University News
March 09, 2012

A bright burst of light has welded these nanowires together.(Photo: Stanford School of Engineering)

The ability to weld nano-sized wires with just a blast of light could lead to advances in electronics and solar applications.  One area of intensive research at the nanoscale is the creation of electrically conductive meshes made of metal nanowires. Promising exceptional electrical throughput, low cost, and easy processing, engineers foresee a day when such meshes are common in new generations of touch screens, video displays, light-emitting diodes, and thin-film solar cells.  Standing in the way, however, is a major engineering hurdle: In processing, these delicate meshes must be heated or pressed to unite the crisscross pattern of nanowires that form the mesh, and are thereby damaged. However, engineers at Stanford University have demonstrated a promising nanowire welding technique that harnesses plasmonics to fuse wires with a simple blast of light. At the heart of the technique is the physics of plasmonics, the interaction of light and metal in which the light flows across the surface of the metal in waves, like water on the beach. “When two nanowires lay criss-crossed, we know that light will generate plasmon waves at the place where the two nanowires meet, creating a hot spot. The beauty is that the hot spots exist only when the nanowires touch, not after they have fused. The welding stops itself. It’s self-limiting,” explains senior Mark Brongersma, associate professor of materials science and engineering at Stanford and an expert in plasmonics. “The rest of the wires and, just as importantly, the underlying material are unaffected,” notes Michael McGehee, also an associate professor of materials science and engineering. “This ability to heat with precision greatly increases the control, speed, and energy efficiency of nanoscale welding.”

Categories : University News
February 23, 2012

Synthesis and characterization of gold nanowires. TEM images showing the assembly of AuNPs on the SWNTs (after 30 min, left) and their welding into AuNWs (after 120 min, right).(Image Source: University of Pittsburgh)

Researchers at theUniversity of Pittsburgh have coaxed gold into nanowires as a way of creating an inexpensive material for detecting poisonous gases found in natural gas. Along with colleagues at the National Energy Technology Laboratory (NETL), Alexander Star, associate professor of chemistry in Pitt's Kenneth P. Dietrich School of Arts and Sciences and principal investigator of the research project, developed a self-assembly method that uses scaffolds (a structure used to hold up or support another material) to grow gold nanowires. “The most common methods to sense gases require bulky and expensive equipment,” says Star. “Chip-based sensors that rely on nanomaterials for detection would be less expensive and more portable as workers could wear them to monitor poisonous gases, such as hydrogen sulfide.” Star and his research team determined gold nanomaterials would be ideal for detecting hydrogen sulfide owing to gold’s high affinity for sulfur and unique physical properties of nanomaterials. They experimented with carbon nanotubes and graphene—an atomic-scale chicken wire made of carbon atoms—and used computer modeling, X-ray diffraction, and transmission electron microscopy to study the self-assembly process. They also tested the resulting materials’ responses to hydrogen sulfide. “To produce the gold nanowires, we suspended nanotubes in water with gold-containing chloroauric acid,” says Star. “As we stirred and heated the mixture, the gold reduced and formed nanoparticles on the outer walls of the tubes. The result was a highly conductive jumble of gold nanowires and carbon nanotubes.” To test the nanowires’ ability to detect hydrogen sulfide, Star and his colleagues cast a film of the composite material onto a chip patterned with gold electrodes. The team could detect gas at levels as low as 5ppb (parts per billion)—a detection level comparable to that of existing sensing techniques. Additionally, they could detect the hydrogen sulfide in complex mixtures of gases simulating natural gas.

Categories : University News
February 02, 2012

Angela Zang.(Image Source: Siemens Foundation)

2011's highest science honor for high school students was awarded recently to biochemistry research on cancer stem cells the 2011 Siemens Competition in Math, Science & Technology, America’s premier science research competition for high school students. Administered by the College Board, the Siemens Competition is a signature program of the Siemens Foundation, which supports science, technology, engineering and mathematics (STEM) education. Angela Zhang, a senior at Monta Vista High School in Cupertino, CA, won the $100,000 Grand Prize in the individual category for using nanotechnology to eradicate cancer stem cells. In her project, "Design of Image-guided, Photo-thermal Controlled Drug Releasing Multifunctional Nanosystem for the Treatment of Cancer Stem Cells," Angela aimed to design a targeted gold and iron oxide-based nanoparticle with the potential to eradicate cancer stem cells through a controlled delivery of the drug salinomycin to the site of the tumor. The multifunctional nanoparticle combines therapy and imaging into a single platform, with the gold and iron-oxide components allowing for both MRI and Photoacoustic imaging. Angela also won the Intel International Science & Engineering Fair (ISEF) Grand Award for medicine and health science in 2011 and 2010. She spent an estimated 1,000 hours on her research. “Angela created a nanoparticle that is like a Swiss army knife of cancer treatment,” said competition judge Dr. Tejal Desai, professor, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco. “She showed great creativity and initiative in designing a nanoparticle system that can be triggered to release drugs at the site of the tumor while also allowing for non-invasive imaging. Her work is an important step in developing new approaches to the therapeutic targeting of tumors via nanotechnology.”

Categories : Competitions/Awards
January 24, 2012

Research from Rice University and the University of California at Berkeley may give science and industry a new way to manipulate graphene, the new material expected to play a role in advanced electronic, mechanical and thermal applications. When graphene – a one-atom thick sheet of carbon – rips under stress, it does so in a unique way that puzzled scientists who first observed the phenomenon. Instead of tearing randomly like a piece of paper would, it seeks the path of least resistance and creates new edges that give the material desirable qualities. Because graphene's edges determine its electrical properties, finding a way to control them will be significant, said Boris Yakobson, Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and professor of chemistry. Yakobson and Vasilii Artyukhov, a postdoctoral researcher at Rice, recreated in computer simulations the kind of ripping observed through an electron microscope by researchers at Berkeley. The California team noticed that cracks in flakes of graphene followed armchair or zigzag configurations, terms that refer to the shape of the edges created. It seemed that molecular forces were dictating how graphene handles stress. Those forces are robust. Carbon-carbon bonds are the strongest known to man. But the importance of this research, Yakobson said, lies in the nature of the edge that results from the rip. The edge of a sheet of graphene gives it particular qualities, especially in the way it handles electric current. Graphene is so conductive that current flows straight through without impediment – until it reaches the edge. What the current finds there makes a big difference, he said, in whether it stops in its tracks or flows to an electrode or another sheet of graphene.

Categories : University News