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Cyber hacking could be a thing of the past
High-profile websites are constantly under threat from hackers attempting to paralyze their websites but new research could make such attacks computationally impossible. This research will be one of the topics discussed at a major international conference on the theory and application of cryptology and information security in Japan this week.
Three papers by academics from Bristol University’s Department of Computer Science will be presented at the ASIACRYPT conference in Tokyo [6 to 10 December].
Security notions and generic constructions for client puzzles will discuss the defense for websites against attackers who launch denial-of-service attacks. Such attacks are becoming more common on the Internet, with high-profile attacks taking place against many leading websites. The paper, from research by Bristol University academics, Paul Morrissey, Nigel Smart, Bogdan Warinschi and Liqun Chen from Hewlett-Packard Laboratories in Bristol, investigates a specific defense technique that aims to make performing such attacks computationally infeasible, while not overburdening the innocent user.
In joint research between Nigel Smart and Steve Williams at Bristol University; Benny Pinkas, University of Haifa, Israel and Thomas Schneider, Ruhr-University at Bochum, Germany, the team show that a procedure thought to be only theoretical can actually be implemented in practice. One goal of this collaboration, entitled Secure two-party computation is practical, is to ultimately allow for databases to compute on encrypted data. Future applications of this research could be for doctors to access centralized healthcare databases in a way that protects patient confidentiality.
In the final paper, Foundations of non-malleable hash and one-way functions, by Bogdan Warinschi from Bristol University; Alexandra Boldyreva and David Cash, Georgia Institute of Technology, USA and Marc Fischlin, Technical University in Darmstadt, Germany, the researchers consider foundational issues related to basic constructions in cryptography. This research is an important step in understanding the properties of a cryptographic object called a ”random oracle”. Such objects are a popular solution in constructing efficient cryptographic schemes, such as those used in a web browser.
Nigel Smart, Professor of Cryptology in the Department of Computer Science at the University of Bristol and co-author on two of the papers, said: “We are delighted to have such a strong presence at this year’s ASIACRYPT conference, especially as it was particularly hard to have papers accepted. Of 300 submissions, just over 40 were selected for presentation at the conference.”
The Bristol component of the work in the three papers is partly funded by two grants from the European Union (eCrypt-2 and CACE), the EPSRC (via a doctoral training grant) and the Royal Society.
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|Source: University of Bristol Permalink: http://www.sflorg.com/comm_center/unv_tech/p971_78.html Time Stamp: 12/7/2009 at 4:55:23 PM UTC|
San Diegans and their Cell Phones will help Computer Scientists Monitor Air Pollution
You want to go for a run, but you don’t want to run in polluted air that might aggravate your asthma. University of California, San Diego computer scientists are creating a network of environmental sensors that will help you avoid air pollution hot spots that exist exactly when you are planning your route. The system will provide up-to-the-minute information on outdoor and indoor air quality, based on environmental information collected by hundreds, and eventually thousands, of sensors attached to the backpacks, purses, jackets and board shorts of San Diegans going about daily life.
This is “CitiSense”—the vision of computer scientists from the UC San Diego Jacobs School of Engineering. The interdisciplinary team recently won a $1.5 million grant from the National Science Foundation (NSF) to solve the many technical challenges that stand in the way of applications that merge the cyber and physical worlds.
“San Diego County has 3.1 million residents, 4,000 square miles, and only five official EPA air quality monitors. We know about the air quality in those exact spots but we know much less about the air quality in other places. Our goal is to give San Diegans up-to-the-minute environmental information about where they live, work and play—information that will empower anyone in the community to make healthier choices,” said William Griswold, the principal investigator on the grant and a professor in the Department of Computer Science and Engineering (CSE) at the UC San Diego Jacobs School of Engineering.
The goal of CitiSense is to build and deploy a wireless network in which hundreds or thousands of small environmental sensors carried by the public rely on cell phones to shuttle information to central computers where it will be analyzed, anonymized and reflected back out to individuals, public health agencies and San Diego at large. At the same time, the sensor-wearing public will have the option to also wear biological monitors that collect basic health information, such as heart rate. This combination of sensors will enable the team’s medical team to run exacting health science research projects, such as investigating how particular environmental pollutants affect human health. Dr. Kevin Patrick from UC San Diego’s California Institute for Telecommunications and Information Technology (Calit2) and the UCSD School of Medicine will lead the medical efforts.
Building a large-scale system that integrates sensors and other digital technologies into the physical world will require advances in a number of computer science areas including power management, privacy, security, artificial intelligence and software architecture. “It is a tremendous challenge to integrate a number of technologies and then deploy them outside—in the wild,” said Griswold.
Mobile phones and other handheld devices, for example, are traditionally designed to serve one person—the user. Including these electronics in advanced computing systems that have other priorities will require new power and workload management strategies. Computer science professor Tajana Simunic Rosing and her graduate students are developing systems to ensure that the phones and other mobile devices serving as stepping stones between environmental sensors and the centralized computing infrastructure will not drop calls or suffer other hits to performance.
Rosing’s team is also investigating how sensors fixed in the environment—rather than carried around by the general public—might be powered by solar, wind, or vibrational energy instead of batteries. In addition, the computer scientists are considering how these fixed sensors might rely on nearby handheld devices to send environmental information to central computers.
Capturing high quality data from sensors in uncontrolled environments is another challenge the computer scientists face. “Sensors will differ. Sensors will fail. People will breathe on them. And so there is the question of how you get good data in these conditions. We have to find a way to process the data to remove the noise,” said Griswold, who noted that computer science professor Sanjoy Dasgupta and a team of student researchers is using statistical artificial intelligence (AI) to do just this.
Computer science professor Hovav Shacham will lead a team focused on security and privacy issues, which are particularly challenging given the limited computational power of sensors and other embedded devices.
Software architecture and cyberinfrastructure are additional areas in which breakthroughs will be needed. The computer scientists are developing new approaches to writing code for software systems that are open and flexible yet private and secure.
For example, if someone develops a new application for monitoring carbon dioxide, the computer scientists want to be able to drop the application into the system and have it not only work—but interact with existing systems in terms of data, power management and workflow. Computer science professors Ingolf Krueger and William Griswold are leading these efforts. In part, they are building on Krueger’s previous work in service-oriented architecture, which can keep various components—like machine learning, power management and security code—much more separate than in traditional software systems, where functional elements are often so woven into the source code that it is difficult to quickly update any one aspect of the software.
“We are addressing major problems of the day of tremendous social, environmental and economic importance. When you attach the science and engineering to the problems of the day, it drives the research in a very exciting way,” said Griswold.
|Image Caption: The CitiSense leadership team (l-r) includes computer science professor William Griswold, computer science professor Ingolf Krueger, School of Medicine/Calit2 professor Kevin Patrick, computer science professor Tajana Simunic Rosing, and computer science professor Hovav Shacham. (Not pictured: computer science professor Sanjoy Dasgupta). Image Credit: UC San Diego Jacobs School of Engineering Source: UC San Diego Jacobs School of Engineering Permalink: http://www.sflorg.com/comm_center/unv_tech/p963_77.html Time Stamp: 12/2/2009 at 6:19:20 PM UTC|
New Method to Measure Snow, Soil Moisture With GPS May Benefit Meteorologists, Farmers
A research team led by the University of Colorado at Boulder has found a clever way to use traditional GPS satellite signals to measure snow depth as well as soil and vegetation moisture, a technique expected to benefit meteorologists, water resource managers, climate modelers and farmers.
The researchers have developed a technique that uses interference patterns created when GPS signals that reflect off of the ground -- called "multipath" signals -- are combined with signals that arrive at the antenna directly from the satellite, said CU-Boulder aerospace engineering sciences Professor Kristine Larson, who is leading the study. Since such multipath signals arrive at GPS receivers "late," they have generally been viewed as noise by scientists and engineers and have largely been ignored, said Larson, who is leading a multi-institution research effort on the project.
In one recent demonstration, the team was able to correlate changes in the multipath signals to snow depth by using data collected at a field site in Marshall, Colo. just south of Boulder, which was hit by two large snowstorms over a three-week span in March and April of 2009. Published in the September issue of Geophysical Research Letters, the snowpack study built on a project Larson and her colleagues have been working on that is funded by the National Science Foundation to measure soil moisture using GPS receivers.
The new study on snow and vegetation moisture will be presented at the fall meeting of the American Geophysical Union being held in San Francisco Dec. 14 to 18.
Larson's group is the first to use traditional GPS receivers -- which were designed for use by surveyors and scientists to measure plate tectonics and geological processes -- to assess snowpack, soil moisture and vegetation moisture. The team hopes to apply the technique to data collected from an existing network of more than 1,000 GPS receivers in place around the West known as the Plate Boundary Observatory, a component of NSF's Earthscope science program.
"By using the Plate Boundary Observatory for double duty, so to speak, we hope this will be a relatively inexpensive and accurate method that can benefit climate modelers, atmospheric researchers and farmers throughout the West," said Larson.
Study collaborators, all from Boulder, include CU-Boulder's Eric Small and Mark Williams, John Braun from the University Corporation for Atmospheric Research, Ethan Gutmann from the National Center for Atmospheric Research and Valery Zavorotny and Andria Bilich from National Oceanic and Atmospheric Administration.
The most recent effort by the team has been conducted in cooperation with Munson Farms of Boulder. The new experiment is designed to analyze how the GPS signals traveling through alfalfa, corn and grass correlate with the amount of water in the vegetation. Small and CU-Boulder students have been cutting and weighing both wet and dry vegetation and matching the sample weights with comparative GPS multipath signal changes using a receiver set up at the farm.
The team is collaborating with Bob Munson, owner of Munson Farms and a former antenna engineer at Ball Aerospace & Technologies of Boulder. Munson holds more than 30 patents related to antenna design, including one of the most widely used antennas for GPS applications like vehicle navigation and recreational applications.
"With this system, the GPS antenna allows us to see across a whole field, unlike individual moisture sensors that are sometimes set up to measure only small, specific areas," Munson said. If a farmer relied on data from only a single soil moisture sensor that happened to be in a particularly dry pocket of his crop field, for example, it could have a negative effect on the timing and quality of the harvest, he said.
Originally developed in the 1970s for military use, GPS technology is in wide use today, telling drivers and hikers their exact position on the planet and providing directions to their destinations by gathering at least four signals simultaneously from the 31 GPS satellites now orbiting Earth.
Braun, who received his doctorate from CU-Boulder in 2004, also is interested in observing water vapor in the atmosphere by measuring the delay of GPS signals as they propagate through the atmosphere. "Water scarcity is going to be a problem for the western United States in the coming century," he said. "Having improved observations of water in all of its phases is going to be an important step as we monitor changes in the environment, which is the most intriguing part of this project for me."
Larson helped to pioneer the use of GPS as a tool to measure the movement of tectonic plates and the crustal deformation associated with earthquakes as a graduate student at the University of California-San Diego in 1980s. "Even then we knew that the data were corrupted by ground reflection, which was really irritating," she said. "But it was only recently that we began to think maybe there was a way to use these ground reflections to our benefit."
All of the team's research efforts revolve around the water cycle, said Larson. "We want to know if the water is in the ground, in the snow or in the vegetation, and how much is evaporating into the atmosphere, since it will ultimately be returned to the Earth's surface through precipitation events."
|Source: University of Colorado at Boulder Permalink: http://www.sflorg.com/comm_center/unv_tech/p948_76.html Time Stamp: 11/20/2009 at 8:57:27 PM UTC|
'Fingerprinting' RFID Tags: Researchers Develop Anti-Counterfeiting Technology
Engineering researchers at the University of Arkansas have developed a unique and robust method to prevent cloning of passive radio frequency identification tags. The technology, based on one or more unique physical attributes of individual tags rather than information stored on them, will prevent the production of counterfeit tags and thus greatly enhance both security and privacy for government agencies, businesses and consumers.
“RFID tags embedded in objects will become the standard way to identify objects and link them to the cyberworld,” said Dale R. Thompson, associate professor of computer science and computer engineering. “However, it is easy to clone an RFID tag by copying the contents of its memory and applying them to a new, counterfeit tag, which can then be attached to a counterfeit product – or person, in the case of these new e-passports. What we’ve developed is an electronic fingerprinting system to prevent this from happening.”
Thompson and Jia Di, associate professor of computer science and computer engineering and co-principal investigator on the project, refer to the system as a fingerprint because they discovered that individual tags are unique, not because of the data or memory they contain, but because of radio-frequency and manufacturing differences.
As Thompson mentioned, RFID tags are becoming more prevalent. They have been used in a wide range of applications, including government processes, industry and manufacturing, supply-chain operations, payment and administration systems, and especially retail.
“In spite of this wide deployment, security and privacy issues have to be addressed to make it a dependable technology,” Thompson said.
A passive RFID tag harvests its power from an RFID reader, which sends radio frequency signals to the tag. The tag, which consists of a microchip connected to a radio antenna, modulates the signal and communicates back to the reader. Working with an Avery Dennison M4E testcube designed for determining the best placement of RFID tags on packages, Thompson, Di and students in the Security, Network, Analysis and Privacy Lab measured tags’ minimum power response at multiple frequencies.
The researchers did this using an algorithm that repeatedly sent reader-to-tag signals starting at a low power value and increasing the power until the tag responded. Radio frequencies ranged from 903 to 927 megahertz and increased by increments of 2.4 megahertz. These measurements revealed that each tag had a unique minimum power response at multiple radio frequencies. Moreover, power responses were significantly different for same-model tags.
“Repeatedly, our experiments demonstrated that the minimum power response at multiple frequencies is unique for each tag,” Thompson said. “These different responses are just one of several unique physical characteristics that allowed us to create an electronic fingerprint to identify the tag with high probability and to detect counterfeit tags.”
Like other electronics equipment, cost and size have driven development of RFID technology. This emphasis means that most tags have limited computational capabilities; they do not include conventional encryption algorithms and security protocols to prevent cloning and counterfeiting. The electronic fingerprinting system addresses these concerns without increasing the cost or physically modifying the tag, Thompson said. The method can be used along with other security protocols for identification and authentication because it is independent of the computational capabilities and resources of the tag.
Thompson and Di are also developing network circuits that are resistant to side-channel attacks against readers and tags.
|Source: University of Arkansas Permalink: http://www.sflorg.com/comm_center/unv_tech/p943_75.html Time Stamp: 11/19/2009 at 7:32:02 AM UTC|
Embargo Till: 09:00 UTC September 07, 2009
Nano Research Has Strong Multidisciplinary Roots
The burgeoning research fields of nanoscience and nanotechnology are commonly thought to be highly multidisciplinary because they draw on many areas of science and technology to make important advances.
Research reported in the September issue of the journal Nature Nanotechnology finds that nanoscience and nanotechnology indeed are highly multidisciplinary – but not much more so than other modern disciplines such as medicine or electrical engineering that also draw on multiple areas of science and technology.
With $1.6 billion scheduled to be invested in nano-related research during 2010, assessing the multidisciplinary nature of the field could be important to policy-makers, research managers, technology-transfer officers and others responsible for managing the investment and creating a supportive environment for it.
“Research in nanoscience and nanotechnology is not just a collection of isolated ‘stove pipes’ drawing knowledge from one narrow discipline, but rather is quite interdisciplinary,” said Alan Porter, co-author of the paper and a professor emeritus in the Schools of Industrial and Systems Engineering and Public Policy at the Georgia Institute of Technology. “We found that research in any one category of nanoscience and nanotechnology tends to cite research in many other categories.”
The study was sponsored by the National Science Foundation through the Center for Nanotechnology in Society at Arizona State University.
Porter and collaborator Jan Youtie, manager of policy services in Georgia Tech’s Enterprise Innovation Institute, analyzed abstracts from more than 30,000 papers with “nano” themes that were published between January and July of 2008. They found that although materials science and chemistry dominated the papers, fields as diverse as clinical medicine, biomedical sciences and physics also contributed.
These “nanopapers” studied by the researchers appeared in more than 6,000 journals that were part of a database known as the Science Citation Index (SCI). The researchers found nanopapers in 151 of SCI’s 175 subject categories, with 52 of the categories containing more than 100 such papers.
To explore how well knowledge was integrated across the disciplines, the researchers also studied the journal articles that were cited in the nanopapers. They found more than one million cited references, a mean of 33 per paper.
Using text mining techniques to extract sources from the cited references, they further found that 45 subject categories were cited by five percent or more of the nanopapers – and 98 categories that were cited by at least one percent of the papers. The text mining was done using VantagePoint software developed by Georgia Tech and Search Technology Inc.
Six subject categories dominated both the original nanopapers and the cited references. Each of the six contained 10 percent or more of the original nanopapers and was cited by 39 percent or more of the references.
The researchers found considerable interdisciplinary representation within those six categories. Though 86 percent of the 3,863 nanopapers in the “nanoscience and nanotechnology” category cited papers in materials science, another 80 subject categories had 40 or more cited papers each.
This representation continued even outside the top six categories. The 808 nanopapers in electrical engineering cited papers in journals from 138 different subject categories, while the 435 nanopapers in organic chemistry cited papers in journals from 140 different subject categories.
The researchers also used a metric they called an “integration score” to gauge how interdisciplinary nature of a particular paper or set of papers. The integration score ranged from zero for stand-alone disciplines that don’t cite work from other disciplines to one for highly-integrated disciplines that heavily cite work from other areas.
Integration scores ranged from 0.65 for nanoscience and nanotechnology to 0.60 for electrical engineering and 0.64 for organic chemistry.
“Our results show the multidisciplinary nature of research in nanoscience and nanotechnology, although the integration scores make it clear that much non-nano research is also comparably interdisciplinary,” Porter said. “Much of the nanoresearch is also concentrated in ‘macrodisciplines’ such as materials science and chemistry, and researchers tend to cite work from neighboring fields more often than work in more distant fields.”
Understanding the interdisciplinary nature of nanoscience and nanotechnology could be important to creating the right environment for the field to produce results.
“There is a broad perspective that most scientific breakthroughs occur at the interstices among more established fields,” said Youtie. “Nanotechnology R&D is believed to be an area where disciplines converge. If nanotechnology does have a strong multidisciplinary character, attention to communication across disciplines will be an important feature in its emergence.”
In the future, Porter and Youtie hope to explore other policy-focused nano topics, including:
• How research and
development patterns can forecast likely commercial
“A nanodistrict is a regional concentration of research institutions and firms where nanotechnologies are developed,” Youtie explained. “Although nanotechnology applications are deployed widely across the world, a smaller number of nanodistrict locations are appearing where nanotechnology research, development and initial commercialization are clustered.”
The Center for Nanotechnology in Society is part of a broad U.S. effort to anticipate the societal implications of nanotechnology. Georgia Tech’s role in the multi-university effort is to characterize the type of nanotechnology research being done and to identify early indicators of emerging technologies in that field.
Youtie and Porter are also part of Georgia Tech’s Program in Science, Technology and Innovation Policy (STIP), a collaboration of the School of Public Policy and the Enterprise Innovation Institute that advances research and practice in science, technology, innovation and spatial development policy.
|Image Caption 1: Figure shows the position of nanoscience and nanotechnology over a base map of science. Each node is one of 175 subject categories in the SCI database, and the size of the node is proportional to the number of nanopapers published. Image Caption 2: Figure shows the fields of science cited by nanotechnology papers. Image Credits: Alan Porter and Jan Youtie. / Georgia Institute of Technology Source: Georgia Institute of Technology Permalink: http://www.sflorg.com/comm_center/unv_tech/p926_74.html Time Stamp: 9/7/2009 at 09:00:00 UTC|
Embargo Till: 18:00 UTC August 20, 2009
Teaching Magnets to Do More than Just Stick Around
That palm tree magnet commemorating your last vacation is programmed for a simple function " to stick to your refrigerator. Similarly, semiconductors are programmed to convey bits of information small and large, processing information on your computer or cell phone.
Scientists are working to coax those semiconductors to be more than conveyers, to actually perform some functions like magnets, such as data recording and electronic control. So far most of those effects could only be achieved at very cold temperatures: minus 260 degrees Celsius or more than 400 below zero Fahrenheit, likely too cold for most computer users.
However, researchers led by a University of Washington chemist report Friday (Aug. 22) in Science that they have been able to train tiny semiconductor crystals, called nanocrystals or quantum dots, to display new magnetic functions at room temperature using light as a trigger.
Silicon-based semiconductor chips incorporate tiny transistors that manipulate electrons based on their charges. Scientists also are working on ways to use electricity to manipulate the electrons' magnetism, referred to as "spin," but are still searching for the breakthrough that will allow "spintronics" to function at room temperature without losing large amounts of the capability they have at frigid temperatures.
The team led by Daniel Gamelin, a UW chemistry professor, has found a way to use photons " tiny light particles " to manipulate the magnetism of semiconductor nanocrystals efficiently, even up to room temperature.
"This provides a completely new approach to microelectronics, if you can use spin instead of charge to process information and use photons to manipulate that process," Gamelin said. "It opens the door to materials that store information and perform logic functions at the same time without the need for super cooling."
The team used nanocrystals of a cadmium-selenium semiconductor called cadmium selenide, but replaced some nonmagnetic cadmium ions with magnetic manganese ions. The crystals, smaller than 10 nanometers across (a nanometer is one-billionth of an inch), were then suspended in a colloid solution, like droplets of cream suspended in milk.
Beams of photons were used to align all of the manganese ions' spins, creating magnetic fields as much as 500 times more powerful than in the same semiconductor material without manganese. The magnetic effects were strongest at low temperatures, but remained remarkably strong up to room temperature, Gamelin said.
Besides Gamelin, authors of the Science paper are Remi Beaulac and Paul Archer of the UW and Lars Schneider and Gerd Bacher of the University of Duisburg-Essen in Germany.
In a second paper published Sunday (Aug. 16) in the online edition of Nature Nanotechnology, Gamelin's group reported related effects in semiconductor nanocrystals made of zinc oxide but also containing small amounts of manganese impurities.
With zinc oxide, photons acted more as an on-off switch " once photons altered the zinc oxide's magnetism, the photon stream could be removed and the effect remained in place until another stimulus was applied to turn the effect off again.
Besides Gamelin, authors of the Nature Nanotechnology paper are Stefan Ochsenbein, Yong Feng, Kelly Whitaker, Ekaterina Badaeva, William Liu and Xiaosong Li, all of the UW.
Some behaviors described in the papers have been seen previously at very low temperatures, but in those cases the active materials were embedded in other crystals and so could not be isolated or processed. Suspending the nanocrystals in a colloid solution brings the magnetic effects into a new functional form that could be useful for integration with unconventional materials, Gamelin said. For example, the solution containing the crystals could be applied to a film using a device like an ink jet printer, or interfaced with carbon-based materials using techniques not typically practical for magnetic semiconductors.
"We've brought these spin effects into a processable form," he said. "I think both of these papers are converging on the same applications. We're exploring how to manipulate spins in these nanostructures and perhaps opening the door for some exciting new technologies."
Funding for the work in the two papers came from the U.S. National Science Foundation, the Dreyfus Foundation, the Sloan Foundation, the Natural Sciences and Engineering Research Council of Canada, the German Research Foundation, Gaussian Inc., the Research Corp., the Swiss National Science Foundation and the University of Washington.
|Source: University of Washington Permalink: http://www.sflorg.com/comm_center/unv_tech/p907_73.html Time Stamp: 8/20/2009 at 18:00:00 UTC|
Embargo Till: 16:00 UTC August 19, 2009
Bio-enabled Technique Produces Nanocomposites
Using thin films of silk as templates, researchers have incorporated inorganic nanoparticles that join with the silk to form strong and flexible composite structures that have unusual optical and mechanical properties. This bio-enabled, surface-mediated formation approach mimics the growth and assembly processes of natural materials, taking advantage of the ability of biomolecules to chemically reduce metal ions to produce nanoparticles without harsh processing conditions.
Less than 100 nanometers thick, silk-silver nanoparticle composite films formed in this process can be used for flexible mirrors and films that reflect light in specific wavelengths. The technique could also be used to create anti-microbial films, thin film sensors, self-cleaning coatings, catalytic materials and potentially even flexible photovoltaic cells.
"We are taking advantage of biological molecules that have the ability to bind metallic ions of silver or gold from solution," said Vladimir Tsukruk, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. "These molecules can create mono-dispersed metallic nanoparticles of consistent sizes under ambient conditions " at room temperature and in a water-based environment without high vacuum or high temperatures.
Sponsored by the Air Force Office for Scientific Research and the Air Force Research Laboratory, the research is scheduled to be described August 19th at the Fall 2009 National Meeting of the American Chemical Society in Washington, D.C.
The nanoparticles produced range in size from four to six nanometers in diameter, surrounded by a biological shell of between one and two nanometers. The silk template permits good control of the nanoparticle placement, creating a composite with equally dispersed particles that remain separate. The optical properties of the resulting film depend on the nanoparticle material and size.
"This system provides very precise control over nanoparticle sizes," said Eugenia Kharlampieva, a postdoctoral researcher in Tsukruk's laboratory. "We produce well-defined materials without the problem of precipitation, aggregation or formation of large crystals. Since the silk fibroin is mono-dispersed, we can create uniform domains within the template."
Fabrication of the nanocomposites begins by dissolving silk cocoons and making the resulting fibroin water soluble. The silk is then placed onto a silicon substrate using a spin-coating technique that produces multiple layers of thin film that is then patterned into a template using a nanolithography technique.
"Because silk is a protein, we can control the properties of the surface and design different kinds of surfaces," explained Kharlampieva. "This surface-mediated approach is flexible at producing different shapes. We can apply the method to coat any surface we want, including objects of complex shapes."
Next, the silk template is covered with a solution containing ions of gold, silver, or other metal. Over a period of time ranging from hours to days, the nanoparticles form within the template. The relatively long growth time, which operates at room temperature and neutral pH in a water-based environment, allows precise control of the particle size and spacing, Tsukruk noted.
"We operate at conditions that are suitable for biological activities," he said. "No reducing agents are required to produce the particles because the biomolecules serve as reducing agents. We don't add any chemicals that could be toxic to the protein."
Use of these mild processing conditions reduces the cost producing the composites and their potential environmental impact. When dried, the resulting silk-nanoparticle film has high tensile strength, high elasticity and toughness.
"Silk is almost as strong as Kevlar, but it can be deformed by 30 percent without breaking," said Tsukruk. "The silk film is very robust, with a complicated structure that you don't find in synthetic materials."
For the future, the researchers plan to use the bio-assisted, surface-mediated technique to produce nanoparticles from other metals. They also hope to combine different types of particles to create new optical and mechanical properties.
"If we combine gold-binding and silver-binding peptides, we can make composites that will include a mixture of gold and silver nanoparticles," said Kharlampieva. "Each particle will have its own properties, and combining them will create more interesting composite materials."
The researchers also hope to find additional applications for the films in such areas as photovoltaics, medical technology, and anti-microbial films that utilize the properties of silver nanoparticles.
Beyond Tsukruk and Kharlampieva, the research team has included Dmitry Zimnistky, Maneesh Gupta and Kathryn Bergman of Georgia Tech; David Kaplan of the Department of Biomedical Engineering at Tufts University, and Rajesh Naik of the Materials and Manufacturing Directorate of the Air Force Research Laboratory at Wright-Patterson Air Force Base.
"Nanomaterials grown under environmentally friendly conditions can be as good as synthetic materials that are produced under harsh conditions," Tsukruk added. "This technique allows us to grow very useful materials under natural conditions."
|Image Caption: Georgia Tech researcher Eugenia Kharlampieva studies the properties of composite materials containing silk and metallic nanoparticles. Image Credit: Georgia Institute of Technology / Gary Meek Source: Georgia Institute of Technology Permalink: http://www.sflorg.com/comm_center/unv_tech/p902_72.html Time Stamp: 8/19/2009 at 16:00:02 UTC|
Examining the infinitesimal
A new approach to microscopy is opening up the wonders of the molecular world, allowing researchers to examine organic molecules and delicate crystals as they grow, atom by atom. Dr Andrew Humhpris, co-founder of the original technology and now Chief Technology Officer of Infinitesima, explains how this University spin-out has turned into a leading-edge company.
The smallest bacteria are around 200 nanometers in length; a DNA double helix has a diameter of around two nanometers; and the space between two carbon atoms is only 0.15 nanometers. To put these numbers in context, one nanometer is one billionth of a meter, or the size of a marble when a meter represents the size of the Earth. In other words, incredibly small. With nanotechnology becoming increasingly important in a whole range of scientific fields, being able to see things at higher and higher magnifications is crucial.
There are several ways of looking at materials at the atomic and molecular scale but many, such as scanning electron microscopes, only work in high-vacuum chambers. This can be cumbersome when loading and unloading samples, which also need to be electrically conductive. A different approach is atomic force microscopy (AFM), although the term ‘microscopy’ is something of a misnomer, because this microscope does not really ‘see’ anything. Information is actually gathered by ‘feeling’ the surface of a sample with a probe, much like the needle of a record player moves over the surface of a record. The advantage of AFM is that the sample does not need to be in a vacuum, so live biological material can be examined. Consequently, AFM has been widely used over the past 20 years to move atoms around and even spell out words using individual atoms, but there are still two major drawbacks: the technique is very slow and it cannot be used for very delicate samples, because it damages them in the process.
The advantage of atomic force microscopy is that the sample does not need to be in a vacuum, so live biological material can be examined
Professor Mervyn Miles, Head of the Nanophysics Group in the Physics Department, and his team took these challenges to heart and resolved to change the way AFM systems were designed, but instead of trying to make the probe smaller, they looked at ways to make the measurements faster by increasing the probe’s sensitivity. Using new combinations of materials with which to build the probe, they first managed to reduce the time it took to generate an image from several minutes to just 50 microseconds, thereby enabling the AFM to produce a series of stills that is, in effect, a video of the sample. A key benefit of this approach is that it allows highly delicate samples to be examined, without destroying them in the process. This sensitivity, combined with the video capability, allows biological samples to be examined as they move and crystals to be watched as they grow, atom by atom, revealing a whole new molecular world.
In 2001, the success of this research led to the launch of a spin-out company called Infinitesima in order to develop novel instrumentation and components for existing AFM systems. Instruments were sold to research groups around the world that are pushing back the boundaries of our understanding of molecular activities and by 2004 the company had moved to its current location in Oxford. In 2006, Infinitesima was selected by Real Business magazine as one of the ‘50 to Watch’ start-up companies in the UK. The selection was recognition of the technology, now called Resonant Probe Microscopy (RPM), that Infinitesima brings to the nanotechnology sector.
VideoAFM delivers real-time video at the molecular level and can be operated much like an optical microscope
Infinitesima now supplies several products based on RPM, including VideoAFM which is capable of observing processes and delivering real-time images at unprecedented rates, enabling large areas of sample to be explored. The microscope probe measures just 100 microns across and is made of silicon or silicon nitride, depending on the type of sample being measured. The instrument delivers real-time video at the molecular level, allowing researchers to operate the apparatus much like an optical microscope, but at staggeringly higher magnifications. A technical advisory board, chaired by Professor Mervyn Miles, is made up of leading scientists and researchers in the field who advise the company on its technological development. Today, Infinitesima has a growing number of staff, including a highly experienced management team, and backing from private investors to take the company forward into new areas.
Silicon wafers, for example, need to be inspected closely and quickly for defects, ideally as part of the production line, but current techniques are too slow and require the wafer to be in a vacuum, which is possible but cumbersome. With high-speed atomic-scale imaging in air, wafers can be examined directly to see whether there are any process defects or tiny particles on it – the equivalent of identifying and taking a picture of a single blade of grass in a football pitch. Another area that has recently opened up is in the processing of semiconductors, where a single atom difference in thickness at certain points can dramatically alter the performance of some devices. Being able to examine atoms directly is therefore of tremendous value.
But rather than video, the semiconductor processing industry needs fast, single pictures which the RPM process is able to provide. RPM is therefore being incorporated into semiconductor processing tools to provide these images on high-throughput, continuous production flows. The first of such products from Infinitesima for this large, established industry was introduced in October 2008.
Beyond the semiconductor market, manufacturing of devices of all types is moving towards the nanoscale. From automotive sensors to mobile phone microphones to digital camera lenses, miniaturization has progressed to the point where nanoscale inspection techniques are required to ‘see’ what is being produced and Infinitesima is poised to benefit from this rapidly shrinking world.
|For more information about “Infinitesima” Please visit their web site at: http://www.infinitesima.com/ Source: University of Bristol Permalink: http://www.sflorg.com/comm_center/unv_tech/p887_71.html Time Stamp: 3/18/2009 at 4:59:26 AM UTC|
Researchers Seek To Calm Noise On The Road
Working in collaboration with the Environmental Protection Department (EPD) and the Highways Department, researchers of The Hong Kong Polytechnic University (PolyU) are taking active steps to ease traffic noise generated from frictional contact between vehicle tire and road surface.
According to the Principal Investigator Dr Hung Wing-tat, Associate Professor of PolyU’s Department of Civil and Structural Engineering. The study is made possible with the set up of a sophisticated machine known as the Close-proximity (CPX) Trailer. While traditional measurement of road traffic noise is done along the roadside, the CPX Trailer enables researchers to measure tire-road noise on the road with its unique set up.
“The major merit of the CPX method is its ability to delineate the tire-road noise from the background and thus enable engineers to fully assess the noise reduction effect of various types of low noise materials for road surfacing as well as low noise tires,” said Dr Hung, who is also Researcher of the University’s Hong Kong Road Research Laboratory based in Whitehead of Ma On Shan.
The CPX Trailer was set up with initial funding support from the Environmental Conservation and Wheelock Green Fund. Towed by a four-wheel drive 2300 cc saloon car, the trailer contains an acoustic enclosure covering the test tire and built in with a video-recording camera and two microphones. More importantly, this trailer is tailored to meet the stringent certification requirements of noise measurement and to run on narrow roads in urban areas of Hong Kong.
During the past three years, Dr Hung and his team have been using this CPX Trailer to collect valuable data on tire-road noise in 66 road sections of the territory – very often in the middle of the night. They have reviewed massive data and examined the effects of different factors including driving speed; type of road surface; polymer modified surface; aggregate size and layer thickness; and the choice of tire on tire-road noise.
Their study found that tire-road noise level increases significantly (over 3dB) when the vehicle speed increases from 50 km/hr to 70 km/hr. They also found that the smaller the stone size on road surface and the thicker the layer, the quieter is the road surface at low speed driving (with a difference of 6 dB at 50km/hr). At a reference speed of 70 km/hr, concrete road is the nosiest. The total volume of air void in the pavement surfacing also appears to have an impact on noise reduction.
According to EPD statistics, more than one million Hong Kong people are irritated by road traffic noise of over 70 dB per hour. In the next stage of study, PolyU has been further supported by a HK$1.77 million grant from the Environment and Conservation Fund to develop a new, fully automated CPX vehicle to upgrade the existing Trailer in measuring tire-road noise. PolyU researchers will also probe the effectiveness of low noise tire and the resurfacing of low noise surfacing materials at the same time.
The University will be conducting a series of territory-wide road tests to identify low noise road surfaces and tires in collaboration with the Highways Department and EPD after the newly design CPX vehicle has been fitted and set up to satisfy all related ISO certification requirements.
|Image Caption: Dr Hung Wing-tat nest to the close-proximity (CPX) Trailer Image Credit: Hong Kong Polytechnic University Source: Hong Kong Polytechnic University Permalink: http://www.sflorg.com/comm_center/unv_tech/p881_70.html Time Stamp: 3/16/2009 at 7:24:15 PM UTC|