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What's New in Nanotechnology?

February 26, 2016

Common coaxial cables could be made 50 percent lighter with a new nanotube-based outer conductor developed by Rice University scientists. The Rice lab of Professor Matteo Pasquali has developed a coating that could replace the tin-coated copper braid that transmits the signal and shields the cable from electromagnetic interference. The metal braid is the heaviest component in modern coaxial data cables. Replacing the outer conductor with Rice’s flexible, high-performance coating would benefit airplanes and spacecraft, in which the weight and strength of data-carrying cables are significant factors in performance.Rice research scientist Francesca Mirri made three versions of the new cable by varying the carbon-nanotube thickness of the coating. She found that the thickest, about 90 microns – approximately the width of the average human hair – met military-grade standards for shielding and was also the most robust; it handled 10,000 bending cycles with no detrimental effect on the cable performance. “Current coaxial cables have to use a thick metal braid to meet the mechanical requirements and appropriate conductance,” Mirri said. “Our cable meets military standards, but we’re able to supply the strength and flexibility without the bulk.”

Categories : University News
January 26, 2016
Stanford and IBM researchers inserted chain-like molecules of polystyrene—the same material in a styrofoam coffee cup—between layers of nanocomposites to make these materials tougher and more flexible. (Image Credit: Dauskardt Lab, Stanford University)b, Stanford University)

Stanford and IBM researchers inserted chain-like molecules of polystyrene—the same material in a styrofoam coffee cup—between layers of nanocomposites to make these materials tougher and more flexible.(Image Credit: Dauskardt Lab, Stanford University)

By slipping springy polystyrene molecules between layers of tough yet brittle composites, researchers made materials stronger and more flexible, in the process demonstrating the theoretical limits of how far this toughening technique could go. Researchers at Stanford and IBM have tested the upper boundaries of mechanical toughness in a class of lightweight nanocomposites toughened by individual molecules, and offered a new model for how they get their toughness. The potential applications for nanocomposites cut across many industries, from computer circuitry to transportation to athletics. They could even revolutionize spaceflight with their ability to withstand tension and extreme temperatures. The study was led by Reinhold Dauskardt, a professor of materials science and engineering at Stanford University, and Geraud Dubois, of IBM's Almaden Research Center. The study was sponsored by the Air Force Office of Scientific Research.

January 19, 2016

With the world population expected to reach 9 billion by 2050, engineers and scientists are looking for ways to meet the increasing demand for food without also increasing the strain on natural resources, such as water and energy — an initiative known as the food-water-energy nexus. Ramesh Raliya, PhD, a postdoctoral researcher, and Pratim Biswas, PhD, the Lucy & Stanley Lopata Professor and chair of the Department of Energy, Environmental & Chemical Engineering, both at the School of Engineering & Applied Science at Washington University in St. Louis, are addressing this issue by using nanoparticles to boost the nutrient content and growth of tomato plants. Taking a clue from their work with solar cells, the team found that by using zinc oxide and titanium dioxide nanoparticles, the tomato plants better absorbed light and minerals, and the fruit had higher antioxidant content. Zinc is an essential nutrient for plants, helps other enzymes function properly and is an ingredient in conventional fertilizer. Titanium is not an essential nutrient for plants, Raliya said, but boosts light absorption by increasing chlorophyll content in the leaves and promotes photosynthesis, properties Biswas’ lab discovered while creating solar cells. “When a plant grows, it signals the soil that it needs nutrients,” Biswas said. “The nutrient it needs is not in a form that the plant can take right away, so it secretes enzymes, which react with the soil and trigger bacterial microbes to turn the nutrients into a form that the plant can use. We’re trying to aid this pathway by adding nanoparticles.”

Categories : University News
January 12, 2016
 An artist’s rendering shows the layers of a new, onion-like nanoparticle whose specially crafted layers enable it to efficiently convert invisible near-infrared light to higher energy blue and UV light. Credit: Kaiheng Wei - University at Buffalo

A new, onion-like nanoparticle could open new frontiers in biomaging, solar energy harvesting and light-based security techniques. The research was led by the Institute for Lasers, Photonics, and Biophotonics at the State University of New York University at Buffalo and the Harbin Institute of Technology in China, with contributions from the Royal Institute of Technology in Sweden, Tomsk State University in Russia, and the University of Massachusetts Medical School.  The particle’s innovation lies in its layers: a coating of organic dye, a neodymium-containing shell, and a core that incorporates ytterbium and thulium. Together, these strata convert invisible near-infrared light to higher energy blue and UV light with record-high efficiency, a trick that could improve the performance of technologies ranging from deep-tissue imaging and light-induced therapy to security inks used for printing money. When it comes to bioimaging, near-infrared light could be used to activate the light-emitting nanoparticles deep inside the body, providing high-contrast images of areas of interest. In the realm of security, nanoparticle-infused inks could be incorporated into currency designs; such ink would be invisible to the naked eye, but glow blue when hit by a low-energy laser pulse — a trait very difficult for counterfeiters to reproduce.

Categories : University News
January 05, 2016
 Schematic showing a new engineered surface that can repel liquids in any state of wetness.<br />Image: Xianming Dai, Chujun Zeng and Tak-Sing Wong/Penn State

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets still stick to them. Now, Penn State researchers have developed nano/micro-textured, highly slippery surfaces able to outperform these naturally inspired coatings, particularly when the water is a vapor or tiny droplets. Enhancing the mobility of liquid droplets on rough surfaces could improve condensation heat transfer for power-plant heat exchangers, create more efficient water harvesting in arid regions, and prevent icing and frosting on aircraft wings. "This represents a fundamentally new concept in engineered surfaces," said Tak-Sing Wong, assistant professor of mechanical engineering and a faculty member in the Penn State Materials Research Institute. "Mobility of liquid droplets on rough surfaces is highly dependent on how the liquid wets the surface. We have demonstrated for the first time experimentally that liquid droplets can be highly mobile when in the Wenzel state." Liquid droplets on rough surfaces come in one of two states: Cassie, in which the liquid partially floats on a layer of air or gas, and Wenzel, in which the droplets are in full contact with the surface, trapping or pinning them. "Through careful, systematic analysis, we found that the Wenzel equation does not apply for highly wetting liquids," said Birgitt Boschitsch Stogin, graduate student in Wong's group. In order to make Wenzel state droplets mobile, the researchers etched micrometer scale pillars into a silicon surface using photolithography and deep reactive-ion etching, and then created nanoscale textures on the pillars by wet etching. They then infused the nanotextures with a layer of lubricant that completely coated the nanostructures, resulting in greatly reduced pinning of the droplets. The nanostructures also greatly enhanced lubricant retention compared to the microstructured surface alone. The same design principle can be easily extended to other materials beyond silicon, such as metals, glass, ceramics and plastics. The authors believe this work will open the search for a new, unified model of wetting physics that explains wetting phenomena on rough surfaces.

Categories : University News
December 21, 2015
The prototype listeria biosensor chip is a little smaller than postage stamp. Dr. Carmen Gomes, Texas A&amp;M AgriLife Research engineer, said even at this early stage of development, the sensor can detect as little as one bacterium in about one ounce of food product. (Texas A&amp;M AgriLife Communications photo by Robert Burns)

Dr. Carmen Gomes, AgriLife Research engineer with the Texas A&M University and Dr. Eric McLamore at the University of Florida at Gainesville have developed a biosensor that can detect listeria bacterial contamination within two or three minutes. “We hope to soon be able to detect levels as low as one bacteria in a 25-gram sample of material – about one ounce,” said Gomes. The same technology can be developed to detect other pathogens such as E. coli O157:H7, she said. But listeria was chosen as the first target pathogen because it can survive even at freezing temperatures. It is also one of the most common foodborne pathogens in the world and the third-leading cause of death from food poisoning in the U.S. Currently, the only means of detecting listeria bacteria contamination of food requires highly trained technicians and processes that take several days to complete, she said. The biosensor she is working on is still in the prototype stage of development, but in a few years she envisions a hand-held device that will require hardly any training to use. Gomes said she is using “nanobrushes” specially designed to grab particular bacteria. The nanobrushes utilize “aptamers,” which are single-stranded DNA or RNA molecules that bind to the receptors on the target organism’s cell outer membrane, Gomes said. This “binding” is often compared to the way a key fits into only one lock. In this manner, the nanobrushes select for only a specific type of cell, which in the case of her work is the listeria bacterium. Currently, the listeria biosensor is about the size of a postage stamp, with two wires leading to two etched conductive areas. After a few minutes, when the polymer nanobrushes have had time to grab the selected bacteria, the rest of the sample is washed away and the impedance, or resistance, between the two surfaces is measured electronically. In early April, the team was awarded a three-year $340,000 National Science Foundation grant to continue their work on nanobrushes for pathogen detection.

Categories : University News
December 15, 2015
In the light-activated nanoparticles studied by Thomann and colleagues at Rice’s Laboratory for Nanophotonics (LANP), light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles. (Image Credit: Rice University)

Rice Universityresearchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules. The technology relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy to highly excited electrons, which scientists sometimes refer to as “hot electrons.” Capturing these high-energy electrons before they cool could allow solar-energy providers to significantly increase their solar-to-electric power-conversion efficiencies and meet a national goal of reducing the cost of solar electricity.“Hot electrons have the potential to drive very useful chemical reactions, but they decay very rapidly, and people have struggled to harness their energy,” said lead researcher Isabell Thomann, assistant professor of electrical and computer engineering and of chemistry and materials science and nanoengineering at Rice. “For example, most of the energy losses in today’s best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat.” In the light-activated nanoparticles studied by Thomann and colleagues at Rice’s Laboratory for Nanophotonics (LANP), light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles. Plasmons are high-energy states that are short-lived, but researchers at Rice and elsewhere have found ways to capture plasmonic energy and convert it into useful heat or light. Plasmonic nanoparticles also offer one of the most promising means of harnessing the power of hot electrons, and LANP researchers have made progress toward that goal in several recent studies.

Categories : University News
December 06, 2015

The recently launched EU ASCENT project recently held its 1st Users Workshop at the XXIV International Scientific Conference ‘Electronics - ET2015’ in Bulgaria. Attendees heard how ASCENT will enable access to the unique nanoelectronics infrastructure of three of Europe’s premier research centres. The Users Workshops are an important part of the ASCENT mission to support a vibrant nanoelectronics research community across Europe. The three partners (Tyndall, imec and CEA-Leti) will provide researchers with access to advanced device data, test chips, flexible fabrication and characterisation equipment. ASCENT will enable the nanoelectronics modelling-and-characterisation research community to explore exciting new developments in industry and meet the challenges created in an ever-evolving and demanding digital world. ASCENT enables Europe’s world-leading atomic scale device, TCAD and compact modelling community to perform the systematic studies that are required to develop nanoscale design methodologies and to identify the impact of quantum effects on sub-10 nm device performance. It provides an interface to global industrial leaders in nanoelectronics through the Industry Innovation Committee and through activities designed to transfer IP and technology uptake from the supported research activities. The results from the access activities will be fed back to device manufacturers to future improve the nanoscale devices being developed. ASCENT will reach out to the research community through a co-ordinated marketing campaign and will offer a simple single access route to the advanced technologies provided. ASCENT will provide technical and logistical support to Users and the results of the Access activities will be published and shared at User Workshops enabling strong interaction between the Users and Providers.

November 23, 2015
This transmission electron microscope image shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase the strength of concrete. (Purdue Life Sciences Microscopy Center)

Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material. The cellulose nanocrystals (CNCs) could be refined from byproducts generated in the paper, bioenergy, agriculture and pulp industries. They are extracted from structures called cellulose microfibrils, which help to give plants and trees their high strength, lightweight and resilience. Now, researchers at Purdue University have demonstrated that the cellulose nanocrystals can increase the tensile strength of concrete by 30 percent."This is an abundant, renewable material that can be harvested from low-quality cellulose feedstocks already being produced in various industrial processes," said Pablo Zavattieri, an associate professor in the Lyles School of Civil Engineering. The cellulose nanocrystals might be used to create a new class of biomaterials with wide-ranging applications, such as strengthening construction materials and automotive components. One factor limiting the strength and durability of today's concrete is that not all of the cement particles are hydrated after being mixed, leaving pores and defects that hamper strength and durability. "So, in essence, we are not using 100 percent of the cement," Zavattieri said.However, the researchers have discovered that the cellulose nanocrystals increase the hydration of the concrete mixture, allowing more of it to cure and potentially altering the structure of concrete and strengthening it.  As a result, less concrete needs to be used. The cellulose nanocrystals are about 3 to 20 nanometers wide by 50-500 nanometers long - or about 1/1,000th the width of a grain of sand - making them too small to study with light microscopes and difficult to measure with laboratory instruments. They come from a variety of biological sources, primarily trees and plants.

Categories : University News
November 15, 2015
Multimode nanoelectromechanical systems (NEMS) based mass sensor; the main figure schematically depicts a doubly-clamped beam vibrating in fundamental mode (1). Conceptual “snapshots” of the first six vibrational modes are shown below (1-6), colors indicate high (red) to low (blue) strain. The inset shows a colorized electron micrograph of a piezoelectric NEMS resonator fabricated in Caltech’s Kavli Nanoscience Institute. Image Credit: M. Matheny, L.G. Villanueva, P. Hung, J. Li and M. Roukes/Caltech

Building on their creation of the first-ever mechanical device that can measure the mass of individual molecules, one at a time, a team of Caltech scientists and their colleagues have created nanodevices that can also reveal their shape. Such information is crucial when trying to identify large protein molecules or complex assemblies of protein molecules. "You can imagine that with large protein complexes made from many different, smaller subunits there are many ways for them to be assembled. These can end up having quite similar masses while actually being different species with different biological functions. This is especially true with enzymes, proteins that mediate chemical reactions in the body, and membrane proteins that control a cell's interactions with its environment," explains Michael Roukes, the Robert M. Abbey Professor of Physics, Applied Physics, and Bioengineering at Caltech.   With their devices, Roukes and his colleagues can measure the mass of an individual intact molecule. Each device—which is only a couple millionths of a meter in size or smaller—consists of a vibrating structure called a nanoelectromechanical system (NEMS) resonator. When a particle or molecule lands on the nanodevice, the added mass changes the frequency at which the structure vibrates, much like putting drops of solder on a guitar string would change the frequency of its vibration and resultant tone. The induced shifts in frequency provide information about the mass of the particle. But they also, as described in the new paper, can be used to determine the three-dimensional spatial distribution of the mass: i.e., the particle's shape.

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