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A manufacturing renaissance for America?
Wednesday, 31 March 2010 16:15
Over the last few decades, the sector of the U.S. economy devoted to manufacturing has lost ground to the services sector. The number of U.S. manufacturing jobs has declined from nearly 20 million in 1979 to about 12 million today. Yet as the recent global recession suggests, services can propel the economy only so far. There is no substitute for making tangible, useful products.

But what form will new kinds of manufacturing take? At an MIT roundtable discussion on Monday titled “The Future of Manufacturing — Advanced Technologies,” more than a dozen of the Institute’s faculty shared converging ideas about how to reinvigorate America’s goods-producing businesses. The roundtable followed a broader campus forum hosted by MIT President Susan Hockfield on March 1, in which faculty members, some of whom also participated in Monday’s discussion, offered ideas about how to strengthen America innovation and thus its overall economy. These meetings are part of a larger effort by MIT to contribute the Institute’s expertise in emerging technologies and innovation policies to the national effort to revitalize the American economy.

Monday’s discussion cast specific issues of manufacturing in the light of broad economic considerations. “To recover from the current economic downturn, it has been estimated that we need to create on the order of 17 million to 20 million new jobs in the coming decade,” noted Hockfield in her opening remarks at the event, which was co-sponsored by the Council on Competitiveness, an industry group. “And it’s very hard to imagine where those jobs are going to come from unless we seriously get busy reinventing manufacturing.” That question should be of great concern to scientists and engineers — 64 percent of whom, Hockfield noted, are employed in the manufacturing sector.

Hockfield also directly addressed the commonly held notion that the United States cannot compete in manufacturing against low-wage countries, citing the success of Japan and Germany, both of which feature trade surpluses and high wages. “I take this as positive proof that building a strong advanced manufacturing sector is not impossible, but very much worth pursuing,” Hockfield said. In addition to new business practices and continued strength in education, Hockfield added, “A key hope for progress lies in tapping unprecedented new manufacturing technologies.”

Suzanne Berger, a professor of political science and author of How We Compete: What Companies Around the World Are Doing to Make It in Today’s Global Economy, asserted that Americans need to be disabused of the notion that manufacturing is “a ‘sunset sector’ that should be allowed to sink over the horizon.” Increased productivity per worker means the United States still produces 22 percent of the world’s goods, Berger noted, a figure that has been roughly constant for 30 years, and which makes the United States the world’s top manufacturer. Yet the country “has failed to exploit new opportunities for exporting U.S. goods,” she said. “The big problem is not that we can’t compete with China on low wages,” Berger added, but that the United States has “not developed enough kinds of manufacturing that could generate both high profits and also good jobs.”  

Material benefits

The roundtable discussion was organized into two consecutive panels, the first of which focused on innovation in materials science. Gerbrand Ceder, a professor in MIT’s Department of Materials Science and Engineering (DMSE), outlined how a “Materials Genome Project” can catalogue the properties of known materials and allow designers to better model potential devices, thus accelerating product development. “Clearly there are some things that would be useful to apply in many types of manufacturing,” Ceder noted.

Christine Ortiz, an associate professor also in DMSE, described her research group’s efforts to study the nano-scale properties of “high-strength, lightweight, penetration-resistant” biological materials. Those properties could then be transferred to synthetic materials, expanding the range of products that can be manufactured through methods such as 3-D printing.

Charles Fine, a professor at the MIT Sloan School of Management, and Richard Roth, of the Engineering Systems Division, both discussed lightweight automobiles as an alternative to traditional vehicles and an area where the United State could re-establish a competitive advantage in manufacturing. “If we take on the hard challenges and succeed, it’s not so easy to copy,” Fine said. And as Roth noted, “Batteries are extraordinarily expensive,” so new materials research leading to lighter cars would lower those costs by reducing vehicle battery size. In turn, that could make electric automobiles more affordable for consumers and a more appealing investment for manufacturers.

But the actual techniques of manufacturing are what most need to be reinvented, asserted Martin Culpepper, an associate professor in MIT’s Department of Mechanical Engineering. Over the last 150 years, suggested Culpepper, heavy industry has refined large-scale production techniques effectively, and developed myriad tools suited to its needs. But businesses today must invent equally useful nanotechnology-based manufacturing techniques, he believes, allowing firms to better manipulate matter at the smallest scales in order to produce everything from new industrial materials to cutting-edge medicine.

“We don’t have the tools and technologies right now to do a lot of nano-manufacturing in a really practical way,” said Culpepper. Moreover, he believes, researchers today who want to commercialize lab discoveries underestimate the difficulties of “integrating the science and the [manufacturing] process … this is not a trivial thing.”

Culpepper’s own research group aims to create those kinds of small-scale manufacturing tools. Working with one bioscience research institute, he noted, they have been able to roll back the size boundaries of nano-scale DNA arrays, which could make drug production more efficient.

Still, these advances are also restricted, Culpepper said, by the limited number of people with a thorough knowledge of nano-scale manufacturing. “In my lab, it’s like an apprenticeship,” Culpepper said. “It takes a long time to learn how to do this stuff properly.” Universities and their partners, he stated, need to help rectify this problem: “We would like to have more support for training.”

Production values

The second panel discussion centered on technology advances for transforming production. Rodney Brooks of MIT’s Computer Science and Artificial Intelligence Laboratory suggested it is increasingly hard for industry to find places that provide low-cost labor, meaning that U.S. firms should instead seek low-cost manufacturing  technologies. Specifically, manufacturers who use robotics, Brooks said, have gotten “stuck in what was developed in the 1960s. There’s very little integration of sensors and computation with these robots.” As a result of this adherence to inflexible technology, Brooks added, “the integration cost of using robots in industry is 5 to 10 times the capital cost of the robots, and only makes sense if you do the same thing again and again.”  

Bernhardt Trout, a chemical engineering professor and director of the Novartis-MIT Center for Continuous Manufacturing, asserted that the traditional, small-molecule part of the pharmaceuticals industry — firms that make over-the-counter medicines, for instance — invest a “shockingly low” portion of their capital in further product development, instead reaping high profits from existing products, while basic manufacturing technologies have not changed for decades. Trout suggested a streamlined drug-approval process would help motivate industry innovation, but equally claimed the “financialization” of the industry has hurt product development; firms see themselves as “marketing and supply companies.” Advances in academic research, Trout said, are thus especially critical if the industry is to move forward.

The rapid spread of manufacturing know-how has had double-edged effects, observed Sanjay Sarma, an associate professor of mechanical engineering. Profitable industries can now be located around the world, while multinational firms build global supply chains to move products in bulk. “The thing that really hurts manufacturing in the U.S. is the flattening effect that comes from economies of scale,” Sarma said. In response, Sarma suggested domestic manufacturing can become lucrative with the use of “small-lot logistics,” technologies that reduce production and transportation costs and can make many businesses, such as apparel firms, more viable.

However, making new manufacturing environmentally sustainable will be a large challenge, said Timothy Gutowski, also a professor of mechanical engineering. “Here’s the problem: Underpriced ecosystem services provide a competitive advantage,” said Gutowski, meaning that companies who extract natural resources cheaply still have edges in manufacturing. Cooperation between industry and government — and between governments — will be necessary to put new manufacturing on a sound environmental foundation.

Charles Cooney, a professor of chemical engineering moderating the second panel, concluded that three things are important to improving U.S. manufacturing: an understanding of systems thinking, which can help create new, possibly local and regional forms of manufacture and distribution; a recognition that sound public policy will be a necessary part of new development; and a multi-agency approach to science and technology funding, to improve the odds that more forms of research will move from the lab to the factory.


 
Pushing droplets around
Monday, 29 March 2010 00:00
Controlling the way liquids spread across a surface is important for a wide variety of technologies, including DNA microarrays for medical research, inkjet printers and digital lab-on-a-chip systems. But until now, the designers of such devices could only control how much the liquid would spread out over a surface, not which way it would go.

New research from mechanical engineers at MIT has revealed a new approach that, by creating specific kinds of tiny structures on a material’s surface, can make a droplet spread only in a single direction.

A report on the new work, by Esther and Harold E. Edgerton Assistant Professor of Mechanical Engineering Evelyn N. Wang and graduate students Kuang-Han Chu and Rong Xiao, was published on March 28 in the journal Nature Materials.

The system Wang and her team developed is completely passive, based on producing a textured surface with tiny pillars shaped in specific ways to propel liquid in one direction and restrict its movement in others. Once the surface is prepared, no mechanical or electrical controls are needed to propel the liquid in the desired direction, and a droplet placed at any point on the surface will always spread the same way.

It’s just the shapes on the surface that control how the drops spread, rather than the particular materials used, Wang says. The chips used for testing were made at the MIT Microsystems Technology Lab by etching a silicon wafer surface to produce a grid of tiny pillars, which then were selectively coated with gold on one side to make the pillars bend in one direction. To prove that the effect was caused just by the bent shapes rather than some chemical process involving the silicon and gold, the researchers, with the help of Professor Karen Gleason’s group in the Department of Chemical Engineering, then coated the surface with a thin layer of a polymer so that the water would only come in contact with a single type of material. The pillars are all curved in one direction, and cause the liquid to move in that direction.

“Nobody had really studied this kind of geometry, because it’s hard to fabricate,” Wang says.

Wang explains that while this work is still early-stage basic research, in principle such systems could be used for a wide variety of applications. For example, it could provide new ways to manipulate biological molecules on the surface of a chip, for various testing and measurement systems. It might be used in desalination systems to help direct water that condenses on a surface toward a collection system. Or it might allow more precise control of cooling liquids on a microchip, directing the coolant toward specific hotspots rather than letting them spread out over the whole surface.

“It’s a big deal to be able to cool local hotspots on a chip,” Wang says, especially as the components on a chip continue to get smaller and thermal management becomes ever more critical. The research was funded in part by the National Science Foundation, DARPA, and Northrup Grumman.

Mark Shannon, professor of mechanical science and engineering at the University of Illinois, Urbana-Champaign, agrees that this method might be further developed for a variety of applications, including biomedical lab-on-a-chip systems for the detection of specific biomolecules in blood, for example. “Droplet manipulation has been heavily developed for moving samples from station to station for different analysis steps,” he says, and this new method might provide a useful way to do that with minimal energy requirements, but to do so will require the ability to create multiple regions on a surface that propel the liquid in different directions for each stage. “This research will help enable these unit operations,” he says, in combination with related research currently being carried out in other places.

Howard Stone, professor of mechanical and aerospace engineering at Princeton University, who was not involved in this research, says researchers have taken several approaches to surface patterning and control in recent years, some inspired by nature and some by materials applications. “This research advance for one-dimensional asymmetric spreading is a nice addition to the toolbox for surface patterning to control liquid spreading,” he says.



 
Self-assembling computer chips
Tuesday, 16 March 2010 00:00
The features on computer chips are getting so small that soon the process used to make them, which has hardly changed in the last 50 years, won’t work anymore. One of the alternatives that academic researchers have been exploring is to create tiny circuits using molecules that automatically arrange themselves into useful patterns. In a paper that appeared Monday in Nature Nanotechnology, MIT researchers have taken an important step toward making that approach practical.

Currently, chips are built up, layer by layer, through a process called photolithography. A layer of silicon, metal, or some other material is deposited on a chip and coated with a light-sensitive material, called a photoresist. Light shining through a kind of stencil — a “mask” — projects a detailed pattern onto the photoresist, which hardens where it’s exposed. The unhardened photoresist is washed away, and chemicals etch away the bare material underneath.

The problem is that chip features are now significantly smaller than the wavelength of the light used to make them. Manufacturers have developed various tricks to get light to produce patterns smaller than its own wavelength, but they won’t work at smaller scales.

The obvious way to continue shrinking chip features would be to use beams of electrons to transfer mask patterns to layers of photoresist. But unlike light, which can shine through a mask and expose an entire chip at once, an electron beam has to move back and forth across the surface of a chip in parallel lines, like a harvester working along rows of wheat. “It’s like the difference between writing by hand and printing a page all at once,” says Karl Berggren, the Emanuel E. Landsman Associate Professor of Electrical Engineering, who along with Caroline Ross, the Toyota Professor of Materials Science and Engineering, led the new work. The slow, precise scanning of electron-beam lithography makes it significantly more expensive than conventional optical lithography.

Hitchin’ posts

The MIT approach — which Berggren and Ross developed together with Yeon Sik Jung and Joel Yang, who were graduate students at the time — is to use electron-beam lithography sparingly, to create patterns of tiny posts on a silicon chip. They then deposit specially designed polymers — molecules in which smaller, repeating molecular units are linked into long chains — on the chip. The polymers spontaneously hitch up to the posts and arrange themselves into useful patterns.

The trick is that the polymers are “copolymers,” meaning they’re made of two different types of polymer. Berggren compares a copolymer molecule to the characters played by Robert De Niro and Charles Grodin in the movie Midnight Run, a bounty hunter and a white-collar criminal who are handcuffed together but can’t stand each other. Ross prefers a homelier analogy: “You can think of it like a piece of spaghetti joined to a piece of tagliatelle,” she says. “These two chains don’t like to mix. So given the choice, all the spaghetti ends would go here, and all the tagliatelle ends would go there, but they can’t, because they’re joined together.” In their attempts to segregate themselves, the different types of polymer chain arrange themselves into predictable patterns. By varying the length of the chains, the proportions of the two polymers, and the shape and location of the silicon hitching posts, Ross, Berggren, and their colleagues were able to produce a wide range of patterns useful in circuit design.

One of the two polymers that the MIT researchers used burns away when exposed to a plasma (an electrically charged gas), while the other, which contains silicon, turns to glass. The glass layer could serve the same purpose that a photoresist does in ordinary lithography, protecting the material beneath it while that around it is etched away.

Free expression

Dan Herr, the director of nanomanufacturing science research at the Semiconductor Research Corporation, an industry and academic research consortium, says that four or five years ago, his organization polled engineers to determine the seven fundamental shapes that self-organizing molecules would have to be able to assume in order to be useful for circuit manufacture. Since then, he says, researchers have gotten molecules to self-assemble into all seven shapes. But to do so, they’ve “changed the chemistry on the surface or etched down a trench in the surface and used that as a channel for the self-assembling process,” Herr says. Since Berggren and Ross’s technique requires no such channels to guide the self-assembling molecules, it reduces the need for electron-beam lithography. According to Herr, “That will save tremendously in terms of throughput” — that is, the efficiency with which chips can be manufactured.

Much more research is required, however, before self-assembling molecules can provide a viable means for manufacturing individual chips. Nearer term, Berggren and Ross see the technique’s being used to produce stamps that could impart nanoscale magnetic patterns to the surfaces of hard disks, or even to produce the masks used in conventional lithography: today, state-of-the art masks for a single chip require electron-beam lithography and can cost millions of dollars. In the meantime, Ross and Berggren are working to find arrangements of their nanoscale posts that will produce functioning circuits in prototype chips, and they’re trying to refine their technique to produce even smaller chip features.


 
Zooming in on cells
Monday, 15 March 2010 00:00
For two decades, scientists have been pursuing a potential new way to treat bacterial infections, using naturally occurring proteins known as antimicrobial peptides (AMPs) that kill bacteria by poking holes in their cell membranes. Now, MIT scientists have recorded the first real-time microscopic images showing the deadly effects of AMPs in live bacteria.

Researchers led by MIT Professor Angela Belcher modified an existing, extremely sensitive technique known as high-speed atomic force microscopy (AFM) to allow them to image the bacteria in real time. Their method, described in the March 14 online edition of Nature Nanotechnology, represents the first way to study living cells using high-resolution images recorded in rapid succession.

Using this type of high-speed AFM could allow scientists to study how cells respond to other drugs and to viral infection, says Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering and a member of the Koch Institute for Integrative Cancer Research at MIT.

It could also be useful in studying cell death in mammalian cells, such as the nerve cell death that occurs in Alzheimer’s patients, says Paul Hansma, a physics professor at the University of California at Santa Barbara who has been developing AFM technology for 20 years. “This paper is a highly significant advance in the state-of-the-art imaging of cellular processes,” says Hansma, who was not involved in the research.

High speed

Atomic force microscopy, invented in 1986, is widely used to image nanoscale materials. Its resolution (about 5 nanometers) is comparable to that of electron microscopy, but unlike electron microscopy, it does not require a vacuum and thus can be used with living samples. However, traditional AFM requires several minutes to produce one image, so it cannot record a sequence of rapidly occurring events.

In recent years, scientists have developed high-speed AFM techniques, but haven’t optimized them for living cells. That’s what the MIT team set out to do, building on the experience of lead author Georg Fantner, a postdoctoral associate in Belcher’s lab who had worked on high-speed AFM at the University of California at Santa Barbara.

Atomic force microscopy makes use of a cantilever equipped with a probe tip that “feels” the surface of a sample. Forces between the tip and the sample can be measured as the probe moves across the sample, revealing the shape of the surface. The MIT team used a cantilever about 1,000 times smaller than those normally used for AFM, which enabled them to increase the imaging speed without harming the bacteria.

The measurements are performed in a liquid environment, another critical factor in keeping the bacteria alive.

With the new setup, the team was able to take images every 13 seconds over a period of several minutes following treatment with an AMP known as CM15. They found that AMP-induced cell death appears to be a two-step process: a short incubation period followed by a rapid “execution.” They were surprised to see that the onset of the incubation period varied from 13 to 80 seconds.

“Not all of the cells started dying at the exact same time, even though they were genetically identical and were exposed to the peptide at the same time,” says Roberto Barbero, a graduate student in biological engineering and an author of the paper.

Most AMPs act by puncturing bacterial cell membranes, which destroys the delicate equilibrium between the bacterium and its environment. Others appear to target machinery inside the cell. There has been a great deal of interest in developing AMPs as drugs that could supplement or replace traditional antibiotics, but none have been approved yet.

Until a few years ago, it was thought that bacteria could not become resistant to AMPS, but recent studies have shown that they can. The new MIT work could help researchers understand how that resistance develops.

The research was funded by an Erwin-Schrodinger Fellowship, the National Institutes of Health, Army Research Office and Austrian Research Promotion Agency.


 
In The World: Nanotech on the farm
Thursday, 11 March 2010 23:00
Cassava is a tropical root vegetable and staple crop for millions of people in sub-Saharan Africa. However, it’s tricky to handle: Once the root is removed from the ground, it spoils within one to three days, so farmers must get it to processing centers as soon as possible after harvesting it. If they don’t, the crop goes to waste.

A simple way to prolong cassava’s shelf life could help farmers avoid that waste and sell their crop beyond their local region. Paula Hammond, MIT professor of chemical engineering, and other scientists are now working on an innovative way to help them do that, using nanotechnology — technology that controls material at a molecular or atomic scale. Their idea is to design a plastic storage bag lined with nanoparticles that would react with oxygen, preventing the roots’ oxygen-induced rotting.

“That would enable farmers to harvest and store and process at times convenient to them,” says Hammond, who traveled to Kenya and Ghana last summer with an international group of scientists to meet with farmers and come up with new ways to improve agricultural efficiency.

It may seem odd to send Hammond, a chemical engineer who focuses on nanotechnology, into rural Africa to help farmers. But that’s exactly the point, says Todd Barker, a partner for the Meridian Institute, which organized the trip with funding from the Bill & Melinda Gates Foundation.

Organizers were looking for scientists who specialize in fields not traditionally involved in international development. And they wanted people who knew little or nothing about agriculture, says Barker. “We wanted to get them to look at these particular problems in Africa with a fresh set of eyes.”

‘An important problem’

After the Meridian Institute identified three agricultural chains where farmers needed help — cassava, dairy and maize (corn), Barker enlisted Jeffrey Carbeck PhD ’96, a chemical engineer and entrepreneur, to identify scientists who would fit in with the mission. “I was looking for people who had a deep technical background but had shown they could apply it in multiple areas,” says Carbeck, who knew Hammond from their graduate school days at MIT.

Carbeck thought that Hammond, an expert in designing polymers for drug delivery, sensors and energy, would fit perfectly. Hammond, in turn, was intrigued by the idea. “It sounded like such an important problem, and I had never been to Africa. This was a chance to see it from a very unique perspective,” she says.

Equipped with Land Rovers and digital video cameras, the group of a dozen scientists from around the world traveled to farms throughout the two African nations, talking with farmers to find out the biggest obstacles they face.

For Hammond, the trip was enlightening. “These working families have very immediate problems and have neither the resources, nor perhaps the voice, to express them to groups of elite scientists, and that’s what this allowed them to do,” she says. “These are really exciting problems outside the realm of what we might normally encounter in academia.”

The team found that dairy farmers have a similar problem to cassava farmers — getting their milk to processing centers before it spoils. Most farms don’t have their own refrigeration facilities, so the farmers have to carry their milk in plastic jugs, usually on foot or bicycle, to the nearest cooling center.

If the cooling centers are far from the farm, the farmers might make only one trip a day, so any milk produced after that trip is in danger of spoiling before the next day’s trip. Milk that goes bad is rejected at the center and dumped out.

To avoid that waste, Hammond and other scientists in the group came up with the idea to design a milk container with a nanopatterned, antimicrobial coating that would preserve milk longer than a plain plastic jug.

The African dairy farmers are also interested in a way to easily test their cows to see if they’re pregnant or in heat. Cows must be bred and produce calves in order to produce milk, but if a cow runs dry, it’s difficult to tell whether it’s due to lack of pregnancy or a common udder infection known as mastitis.

There is no simple test for cow pregnancy as there is for humans, but scientists who went on the trip came up with the idea to adapt existing nanopatterned paper sensors to detect bovine pregnancy.

The Gates Foundation originally planned to allocate funding for two or three ideas that came out of the trip, but there were so many (more than 200, later consolidated into 22 concepts), that the foundation is encouraging the scientists to pursue as many as possible. The Meridian Institute will initially focus on diagnostic tools for mastitis, the new milk container, tick-borne disease and other livestock diseases, safety tests for milk, a modified plastic tank for maize storage, and a new way to dry cassava.

The Meridian Institute is now working on starting up a foundation that would serve as an “incubator” to help develop, test and bring these ideas to commercialization, according to Barker. “The major challenge now is to make sure the ideas that came out of the trip reach the farmers in Africa,” he says.

In The World is a column that explores the ways members of the MIT community are developing technology — from the appropriately simple to the cutting edge — to help meet the needs of communities around the planet, especially those in the developing world. If you have suggestions for future columns, please e-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


 
Listening in on single cells
Sunday, 07 March 2010 23:00
MIT researchers have built the first sensor array that can detect single molecules emitted by a living cell. Their sensor targets hydrogen peroxide and could help scientists learn more about that molecule’s role in cancer.

Hydrogen peroxide has long been known to damage cells and their DNA, but scientists have recently uncovered evidence that points to a more beneficial role: it appears to act as a signaling molecule in a critical cell pathway that stimulates cell growth, among other functions.

When that pathway goes awry, cells can grow out of control and become cancerous, so understanding hydrogen peroxide’s role could lead to new targets for potential cancer drugs, says Michael Strano, MIT associate professor of chemical engineering and leader of the research team. Strano and his colleagues describe their new sensor array, which is made of carbon nanotubes, in the March 7 online edition of Nature Nanotechnology.

Strano’s team is also working on carbon nanotube sensors for other molecules, and within the past year has successfully tested and published sensors for nitric oxide and ATP (the molecule that carries energy within a cell).

“The list of biomolecules that we can now detect very specifically and selectively is growing rapidly,” says Strano, who also points out that the ability to detect and count single molecules sets carbon nanotubes apart from many other nanosensor platforms, including electrochemical, electromechanical cantilevers and surface acoustic wave sensors.

Nanotube array

In the new study, Strano’s team used the carbon nanotube array to study the flux of hydrogen peroxide that occurs when a common growth factor called EGF activates its target, a receptor known as EGFR, which is located on cell surfaces. For the first time, the team showed that hydrogen peroxide levels more than double when EGFR is activated.

EGF and other growth factors induce cells to grow or divide through a complex cascade of reactions inside the cell. It’s still unclear exactly how hydrogen peroxide affects this process, but Strano speculates that it may somehow amplify the EGFR signal, reinforcing the message to the cell. Because hydrogen peroxide is a small molecule that doesn’t diffuse far, the signal would be limited to the cell where it was produced.

The team also found that in skin cancer cells, believed to have overactive EGFR activity, the hydrogen peroxide flux was 10 times greater than in normal cells. Because of that dramatic difference, Strano believes this technology could be useful in building diagnostic devices for some types of cancer.

“You could envision a small handheld device, for example, which your doctor could use to assay tissue in a minimally invasive manner and tell if this pathway is corrupted,” he says.

The sensor consists of a film of carbon nanotubes embedded in collagen. Cells can grow on the collagen surface, and the collagen also attracts and traps hydrogen peroxide released by the cell. When the nanotubes come in contact with the trapped hydrogen peroxide, their fluorescence flickers.  By counting the flickers, one can obtain an accurate count of the incident single molecules.

The new sensor represents “an excellent example of the application of nanotechnology to address fundamental questions in biology,” says Ravi Kane, professor of chemical and biological engineering at Rensselaer Polytechnic Institute.

Strano points out that this is the first time an array of sensors with single-molecule specificity has ever been demonstrated.  He and his colleagues derived mathematically that such an array could distinguish “near field” molecular generation from that which takes place far from the sensor surface. 

“Arrays of this type have the ability to distinguish, for example, if single molecules are coming from an enzyme located on the cell surface or from deep within the cell,” says Strano.

In future work, researchers in Strano’s lab plan to study different forms of the EGF receptor to better characterize the hydrogen peroxide flux and its role in cell signaling. They have already discovered that molecules of oxygen are consumed to generate the peroxide.

 
Improved Electric Propulsion Could Boost Satellite Lifetimes
Wednesday, 21 October 2009 19:30
(PhysOrg.com) -- Researchers at the Georgia Institute of Technology have won a $6.5 million grant to develop improved components that will boost the efficiency of electric propulsion systems used to control the positions of satellites and planetary probes.

 
Winners announced in 2009 Collegiate Inventors Competition (source: Eurekalert.org)
Wednesday, 21 October 2009 00:00
(National Inventors Hall of Fame) Winners of 2009 Collegiate Awards Competition announced, including two grand prizes: graduate and undergraduate. (source: Eurekalert.org) - RSS and News widget on Feedzilla.com

 
Harvard scientists bend nanowires into 2-D and 3-D structures (source: Eurekalert.org)
Wednesday, 21 October 2009 00:00
(Harvard University) Taking nanomaterials to a new level of structural complexity, scientists have determined how to introduce kinks into arrow-straight nanowires, transforming them into zigzagging two- and three-dimensional structures with correspondingly... (source: Eurekalert.org) - RSS widgets and RSS feeds on Feedzilla.com

 
Scientists Use Self-Assembly to Make Molecule-Sized Particles With Patches of Charge
Tuesday, 20 October 2009 17:57
(PhysOrg.com) -- Physicists, chemists and engineers at the University of Pennsylvania have demonstrated a novel method for the controlled formation of patchy particles, using charged, self-assembling molecules that may one day serve as drug-delivery vehicles to combat disease and perhaps be used in small batteries that store and release charge.

 
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