Di seguito gli interventi pubblicati in questa sezione, in ordine cronologico.
By adjusting these fields, the transmission of nerve impulses becomes possible and the operation of modern data storage is fulfilled by saving electrical charges (so-called Flash Memories). What researchers have not been able to do is get an ultra-precise reading of electrical fields by using physical measurement techniques. Until now, that is. With the help of one single defect centre in diamond, scientists at the University of Stuttgart in Germany successfully measured electrical fields. Presented in the journal Nature Physics, the study was funded in part by the EU.
Electrical charges use varied ways to control almost 100 % of all physical, chemical or biological processes. A case in point is deoxyribonucleic acid (DNA) and the exact distribution of electrons on it. This distribution is critical for the precise transmission of genetic information, and modern electric circuits trigger electric currents up to single electrons.
Experts say that measuring minor electronic fields linked to the charge is no easy task. Enter the Stuttgart team that devised a new sensor consisting of just one single atom. This nitrogen atom is an impurity captured in diamond, they say.
The team points out that the diamond lattice 'fixes' the atom and enables a laser to address the nuclear vacancy center. "The interaction of the atom with the measured field can be determined by the light emitted by the impurity and, therefore, electrical fields can be measured which are just a fracture of theelectrical field of an elementary charge in 0.1 um distance," the scientists explain.
Because the sensor is about the size of an atom, scientists can measure electrical fields with the same spatial precision. The sensor-generated optical readout enables it to be placed in any geometry. The process also attains its sensitivity and resolution at room temperature and ambient conditions.
While researchers have succeeded in demonstrating the existence of small magnetic fields, this latest finding of combining both measurement techniques permits the measurement of electrical and magnetic fields in a single place without changing the sensor, the team points out.
Thanks to this latest development, novel applications can and will emerge. Measuring the magnetic moments' distribution of the chemical compounds' nuclei at the same time is an example, they say, adding that the structure of a substance and its chemical reactivity can be measured simultaneously.
"The ability to sensitively detect individual charges under ambient conditions would benefit a wide range of applications across disciplines," the authors write. "However, most current techniques are limited to low-temperature methods such as single-electron transistors, single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we introduce a quantum-metrology technique demonstrating precision three-dimensional electric-field measurement using a single nitrogen-vacancy defect centre spin in diamond."
Geoff Dembicki reports extensively on the growing political influence of Alberta's oil sands industry and other climate change-related issues for TheTyee.ca, an award-winning online newspaper based in Vancouver, Canada.
Driving south from Vancouver, Canada, towards Seattle, the scenery is perfectly pastoral with rolling hills and grazing cows. But suddenly, dominating the horizon, the view is interrupted by a phalanx of refinery towers shooting white-gray plumes into the sky. These industrial spires of BP's Cherry Point refinery loom high over Whatcom county, a lush border region a little more than 100 kilometers north of Seattle.
Washington State's largest refining complex provides jet fuel, gasoline and diesel to markets up and down the west coast of North America. I had driven there on a rainy morning last month, hoping to learn more about the economic alchemy that transforms crude oil from Alberta's oil sands and elsewhere into ever ubiquitous aluminum beverage cans.
Photo by Dustin Hicks
Cherry Point plays a little known but critical role in the manufacture of these cans - in fact one-sixth of the world's output would not be possible without an industrial substance produced here in massive volumes each day.
Every year 100 billion soda, beer, and juice cans are cracked open by North Americans each year, almost one can for every person every day. That vast market suggests that transitioning off fossil fuels to halt climate change will be more complicated than the oft-proclaimed solution of switching to a greener forms of transportation.
From Alaska to Alberta
Inside a low brick building at the front of the BP refinery, I shook hands with Bill Kidd, BP's local director of external affairs. “How're you doing?” he exclaimed with a broad smile that made lines appear at the corners of his eyes.
The 52-year-old Kidd, dressed smartly in sleeveless black sweater, slacks and white dress shirt, led me to what passes here as a spacious corner office. Here he explained how Cherry Point is a showcase of North America's oil-boom past and its more troubled future. With the dwindling of easy oil that has gushed from the ground for the last century, the energy industry is in a full-bore search for rich, new reserves, including the oil sands of western Canada.
Built by the Atlantic Richfield Company (ARCO) in 1971 specifically to process crude oil shipped from Alaska's North Slope, Cherry Point was acquired by British Petroleum after the two companies merged in 2000. Today BP (the company dropped the original name in 2001) has become North America's largest oil and gas producer. The company generated profits of US$16.6 billion in 2010 even after a deadly explosion at its offshore Gulf of Mexico Macondo rig created the worst environmental disaster in U.S. history.
For over a decade, the massive Prudhoe Bay reserves and other frigid deposits nearby helped supply refineries on the west coast. Indeed Cherry Point still memorializes those early glory days with a four-foot tall sculpture of a flower with sheet metal petals surrounding an old Prudhoe Bay drill bit.
But production, which peaked at 2.1 million barrels per day in 1989, “has fallen off a cliff,” Kidd told me. Today, daily yield has plummeted to just over 600,000 barrels.
The refinery now sources only half its oil from Alaska, with places as varied as West Africa and Russia helping make up the difference, Kidd said. Most significantly, up to 14 percent of Cherry Point's current crude supply can be traced back to Alberta's vast oil sands reserves, according to trade research conducted by the Borealis Centre for Environment and Trade Research, based on data from the U.S. Department of Energy.
“How much we use specifically is sensitive information,” Kidd told me when I asked him about the figure. “But that is not an outlandish number.”
From Crude to Can
About 90 percent of the crude oil that gets pumped into Cherry Point comes out as gasoline, diesel and jet fuel - the bread and butter of North America's refining industry. But the Washington state complex is unique in that it is one of the world's leading providers of a substance essential to the aluminum industry.
When transportation fuels are separated from crude oil, they leave behind a tarry residue. Break down that substance with high temperatures and pressure, and it becomes petroleum coke, a valuable industrial solid. Petcoke, as it is known, gives off intense heat when it burns, making it ideal for the production of cement, steel and certain specialty chemicals. It is also extremely carbon-intensive, releasing almost double the greenhouse emissions of natural gas.
At Cherry Point, some of this petcoke is sent via conveyor belt to the calciner, a collection of large hearths that Kidd compared to a “2,300F degree coffee roaster.”
The finished product, “calcined coke,” is then loaded onto tankers and shipped to aluminum smelters in Australia, Brazil, New Zealand, Canada, and South Africa, according to Borealis. Those smelters in turn outsource their metal to beverage can producers around the world.
When you follow the supply chain all the way back, “one in six aluminum cans is made using BP Cherry Point's calcinated coke,” the company's website brags.
It used to be that most of the refinery's output stayed onshore, Kidd said. Only a generation ago, the U.S. aluminum industry was thriving, shipping 7.3 million tons of metal in 1973, up 21 percent from the year before.
But a booming trend towards global trade hit domestic smelters fast and hard. “Nearly all our aluminum in the next century is probably going to come from offshore countries,” a spokesperson from Ferndale's smelter, only a few kilometers south of Cherry Point, lamented in 1986. The industry could not escape the same economic factors that killed off domestic steel production: relatively high labor and energy costs.
Tune into any discussion on the future of U.S. oil supply and you're going to hear the phrase “energy security” an awful lot. . The debate's gained even more urgency since the Paris-based International Energy Agency (IEA) announced late last year that world conventional oil production likely peaked in 2006.
Critics of continued reliance on fossil fuels argue that these dwindling conventional oil reserves mandate a switch to renewable or even nuclear power. The oil industry however is banking on a different strategy. Notably Republican legislators in the U.S., oil industry lobbyists and Canada's own prime minister, Stephen Harper, have seized onto this fear as a way to promote the oil sands business.
Cherry Point, by relying on the oil sands for up to 14 percent of its crude supply, is helping push the shift from crude oil to unconventional sources. And though the refinery isn't currently considering the pricey upgrades that would let it process even more, BP's Kidd said the prospect isn't too hard to imagine.
“This refinery was built when you had a huge pool of crude in Alaska, the biggest gasoline markets in the world in California and we were right in between. Now you're just moving the supply a little bit east,” he said. “I think it's reasonable to think that more [oil sands] will come this way.”
The refinery's supply-chain narrative - once mighty oil fields in decline, greater reliance on higher-carbon unconventional sources - is being replayed globally. Other North American refineries - such as BP's Whiting complex in Indiana - have invested billions of dollars to handle fast-growing shipments of oil sands crude.
The plan to bring the oil industry into line with changing conditions also includes Keystone XL, a proposed 3,200 kilometer mega-pipeline that travels south from the Canadian province of Alberta to refineries lining the Gulf coast of Texas.
Supporters such as TransCanada, the company proposing to build it, say Keystone XL would “reduce dependence on foreign oil from the Middle East and Venezuela,” and thereby “improve U.S. energy security.”
One of the main reasons why environmental activists oppose this strategy is the impact that the extraction of oil sands have on the province of Alberta, a thousand kilometers to the north west of Cherry Point.
There are up to an estimated 2.5 trillion barrels of crude waiting to be extracted in Alberta. This makes the oil sands North America's largest single source of petroleum, far surpassing Saudi Arabia. But developing those reserves is not an easy - or pretty -- task. Each barrel of oil sands crude must either be clawed from frigid muskeg bogs with industrial-scale shovels, or melted out of underground formations with high-pressure steam and toxic chemicals.
A United Nations water advisor in 2008 compared the region's strip-mined panoramas and sprawling toxic lakes to Mordor, the fictional dark realm of Middle Earth created by J. R. R. Tolkien.
“The air is foul, the water is being drained and poisoned and giant tailing ponds line the Athabasca River,” Canadian environmentalist and author Maude Barlow said at the time.
Alberta's oil sands industry also produces 23 percent more greenhouse gas emissions per barrel than more conventional operations such as those in Prudhoe Bay, a recent European Union report estimated.
The provincial government has argued that report is “unfair” because it uses out-of-date figures. And in 2009 outgoing premier Ed Stelmach told an economic forum in Geneva, Switzerland, that “no matter which extraction method is used, Alberta has some of the most stringent environmental regulations in the world.”
Climate Change Threat
The other reason that critics cite in opposing the oil sand industry is global warming. Only days after I drove to Cherry Point, delegates from more than 180 countries were gathering in Bonn, Germany, for two weeks of climate talks. The mood on day one was sombre as they were confronted by an IEA report showing that greenhouse gases were at record highs, despite 20 years of attempts to control them.
“A serious setback,” is how the IEA's chief economist, Fatih Birol, described the figures.
Part of the reason is that global oil consumption is not going down even though supplies of easy-to-access conventional oil, the very commodity that made a global trade in aluminum cans possible, likely peaked five years ago, as the IEA pointed out last November.
Instead the IEA expects that oil sands, oil shale and extra heavy crude - among the most greenhouse gas-intensive fuel sources on the planet - are filling the gap and are projected to make up roughly 11 percent of global supply by 2030.
This trend “risks tipping the world over the brink in terms of climate damage,” according to a 2010 report by Friends of the Earth Europe.
Yet a radical shift in global efforts to fight climate change -one of the most pressing crises in human history -- seems less and less likely each year. If the world's nations can't limit the Earth's average temperature rise to two degrees above pre-industrial levels, scientists predict that everything from global agriculture to the world's coastal cities will be in peril.
Many environmentalists believe the Obama administration can make a difference by canceling TransCanada's Keystone XL proposal, a pipeline that would pump 800,000 barrels of high-carbon Alberta oil sands crude into the U.S. every day.
“The best way to build energy security in America is through clean, home-grown sources of energy that won't run out -- such as wind and solar for electric vehicles and fuel efficiency and smart growth to reduce our dependence on oil,” Natural Resources Defense Council's Susan Casey-Lefkowitz wrote earlier this year.
Yet switching power and transportation sources are only part of the answer. Closing up my interview at the Cherry Point refinery, I asked Kidd how North America can possibly square its global warming goals with a fossil fuel industry so ubiquitous it's difficult to imagine life without it.
“Obviously,” he replied, the smile now gone from his face, “we're going to have to do something radically different.”
I asked Kidd one final question: “Could we have a global pop, beer and juice can industry without crude oil?”
“Nope,” he replied. “Hydrocarbons in general are incredibly ubiquitous in our economic engine. It isn't just transportation fuel that will be the issue.”
On my drive back to Vancouver I saw crude oil wherever I looked - like an invisible coating on every concrete overpass, eighteen-wheeler semi-truck and pop can discarded on the side of the road.
The question of “energy security” had never seemed so complex.
In the arid Namib Desert on the west coast of Africa, one type of beetle has found a distinctive way of surviving. When the morning fog rolls in, the Stenocara gracilipes species, also known as the Namib Beetle, collects water droplets on its bumpy back, then lets the moisture roll down into its mouth, allowing it to drink in an area devoid of flowing water.
What nature has developed, Shreerang Chhatre wants to refine, to help the world's poor. Chhatre is an engineer and aspiring entrepreneur at MIT who works on fog harvesting, the deployment of devices that, like the beetle, attract water droplets and corral the runoff. This way, poor villagers could collect clean water near their homes, instead of spending hours carrying water from distant wells or streams. In pursuing the technical and financial sides of his project, Chhatre is simultaneously a doctoral candidate in chemical engineering at MIT; an MBA student at the MIT Sloan School of Management; and a fellow at MIT's Legatum Center for Development and Entrepreneurship.
Access to water is a pressing global issue: the World Health Organization and UNICEF estimate that nearly 900 million people worldwide live without safe drinking water. The burden of finding and transporting that water falls heavily on women and children. "As a middle-class person, I think it's terrible that the poor have to spend hours a day walking just to obtain a basic necessity," Chhatre says.
A fog-harvesting device consists of a fence-like mesh panel, which attracts droplets, connected to receptacles into which water drips. Chhatre has co-authored published papers on the materials used in these devices, and believes he has improved their efficacy. "The technical component of my research is done," Chhatre says. He is pursuing his work at MIT Sloan and the Legatum Center in order to develop a workable business plan for implementing fog-harvesting devices.
Interest in fog harvesting dates to the 1990s, and increased when new research on Stenocara gracilipes made a splash in 2001. A few technologists saw potential in the concept for people. One Canadian charitable organization, FogQuest, has tested projects in Chile and Guatemala.
Chhatre's training as a chemical engineer has focused on the wettability of materials, their tendency to either absorb or repel liquids (think of a duck's feathers, which repel water). A number of MIT faculty have made advances in this area, including Robert Cohen of the Department of Chemical Engineering; Gareth McKinley of the Department of Mechanical Engineering; and Michael Rubner of the Department of Materials Science and Engineering. Chhatre, who also received his master's degree in chemical engineering from MIT in 2009, is co-author, with Cohen and McKinley among other researchers, of three published papers on the kinds of fabrics and coatings that affect wettability.
One basic principle of a good fog-harvesting device is that it must have a combination of surfaces that attract and repel water. For instance, the shell of Stenocara gracilipes has bumps that attract water and troughs that repel it; this way, drops collects on the bumps, then run off through the troughs without being absorbed, so that the water reaches the beetle's mouth.
To build fog-harvesting devices that work on a human scale, Chhatre says, "The idea is to use the design principles we developed and extend them to this problem."
To build larger fog harvesters, researchers generally use mesh, rather than a solid surface like a beetle's shell, because a completely impermeable object creates wind currents that will drag water droplets away from it. In this sense, the beetle's physiology is an inspiration for human fog harvesting, not a template. "We tried to replicate what the beetle has, but found this kind of open permeable surface is better," Chhatre says. "The beetle only needs to drink a few micro-liters of water. We want to capture as large a quantity as possible."
In some field tests, fog harvesters have captured one liter of water (roughly a quart) per one square meter of mesh, per day. Chhatre and his colleagues are conducting laboratory tests to improve the water collection ability of existing meshes.
FogQuest workers say there is more to fog harvesting than technology, however. "You have to get the local community to participate from the beginning," says Melissa Rosato, who served as project manager for a FogQuest program that has installed 36 mesh nets in the mountaintop village of Tojquia, Guatemala, and supplies water for 150 people. "They're the ones who are going to be managing and maintaining the equipment." Because women usually collect water for households, Rosato adds, "If women are not involved, chances of a long-term sustainable project are slim."
Whatever Chhatre's success in the laboratory, he agrees it will not be easy to turn fog-harvesting technology into a viable enterprise. "My consumer has little monetary power," he notes. As part of his Legatum fellowship and Sloan studies, Chhatre is analyzing which groups might use his potential product. Chhatre believes the technology could also work on the rural west coast of India, north of Mumbai, where he grew up.
Another possibility is that environmentally aware communities, schools or businesses in developed countries might try fog harvesting to reduce the amount of energy needed to obtain water. "As the number of people and businesses in the world increases and rainfall stays the same, more people will be looking for alternatives," says Robert Schemenauer, the executive director of FogQuest.
Indeed, the importance of water-supply issues globally is one reason Chhatre was selected for his Legatum fellowship.
"We welcomed Shreerang as a Legatum fellow because it is an important problem to solve," notes Iqbal Z. Quadir, director of the Legatum Center. "About one-third of the planet's water that is not saline happens to be in the air. Collecting water from thin air solves several problems, including transportation. If people do not spend time fetching water, they can be productively employed in other things which gives rise to an ability to pay. Thus, if this technology is sufficiently advanced and a meaningful amount of water can be captured, it could be commercially viable some day."
Quadir also feels that if Chhatre manages to sell a sufficient number of collection devices in the developed world, it could contribute to a reduction in price, making it more viable in poor countries. "The aviation industry in its infancy struggled with balloons, but eventually became a viable global industry," Quadir adds. "Shreerang's project addresses multiple problems at the same time and, after all, the water that fills our rivers and lakes comes from air."
That said, fog harvesting remains in its infancy, technologically and commercially, as Chhatre readily recognizes. "This is still a very open problem," he says. "It's a work in progress."
The new work from the Rice lab of biochemist Kathleen Matthews, in collaboration with former Rice faculty fellow and current Texas A&M assistant professor Sarah Bondos, simplifies the process of making materials with fully functional proteins. Such materials could find extensive use as chemical catalysts and biosensors and in tissue engineering, for starters.
Strands of Ubx fiber patterned with fluorescent protein are the result of research by scientists at Rice University and Texas A&M. The strands can contain active proteins that may find use as chemical catalysts and biosensors and in tissue engineering. (Credit: Zhao Huang/Rice University)
Their paper in the online edition of Advanced Functional Materials details a method to combine proteins with a transcription factor derived from fruit flies and then draw it into fine, strong strands that can be woven into any configuration.
Bondos and Matthews led the team that included primary author Zhao Huang and research technician Taha Salim, both of Rice, and research assistants Autumn Brawley and Jan Patterson, both of Texas A&M.
The research had its genesis while Bondos was in Matthews' Rice lab studying Ultrabithorax (Ubx), a recombinant transcription factor protein found in Drosophila melanogaster (the common fruit fly). This protein regulates the development of wings and legs.
"It's biodegradable, nontoxic and made of naturally occurring proteins -- though we have no reason to believe that fruit flies ever produce enough of these proteins to actually make fibers," Bondos said.
It was a surprise, then, to find that Ubx self-assembles into a film under relatively mild conditions.
"I was cleaning up in the lab one morning and I noticed what appeared to be a drop of water suspended in midair beneath a piece of equipment I was using the previous night," Bondos recalled.
It turned out the droplet was water encased in a sac of Ubx film. The sac was hanging by a Ubx fiber so thin that it was more difficult to see than a strand of a spider's web, Bondos said.
"It clued us in that this was making materials," said Matthews, Rice's Stewart Memorial Professor of Biochemistry and Cell Biology and former dean of the Wiess School of Natural Sciences.
The chance discovery prompted a 2009 paper in the journal Biomacromolecules about the material they dubbed "ultrax," a superstrong and highly elastic natural fiber.
"We found that if you put a little drop of this protein solution on a slide, the Ubx forms a film. And if you touch a needle to that film, you can draw a fiber," Matthews said. "Then we asked, What if we could incorporate other functions into these materials? Can we make chimeras?" The answer was yes, though it took ingenuity to prove.
Chimeras in the biological world contain genetically distinct cells from two or more sources. In Greek mythology, chimeras are beings with parts from multiple animals; a pig with wings, for instance, would qualify. But real chimeras are usually more subtle. On the molecular level, chimeras are proteins that are fused into a single polypeptide and can be purified as a single molecular entity.
As a proof of principle, the team used gene-fusion techniques to create chimeras by combining Ubx with fluorescent and luminescent proteins to see if they remained functional. They did. The combined materials still formed a film on water. Drawn into fibers and put under a microscope, Ubx combined with enhanced green fluorescent protein (EGFP) kept its bright green color. Ubx-mCherry was bright red, the brown protein myoglobin (from sperm whales) was brown, and luciferase glowed.
Huang was able to make patterns with strands generated by the chimeras by twisting red and green fluorescent proteins into candy cane-like tubes, or lacing them on a frame. "This patterning technique is pretty unique and very simple," said Huang, who recently defended his thesis on the subject. He said making solid materials with functional proteins often requires harsh chemical or physical processing that damages the proteins' effectiveness. But creating complex three-dimensional structures with Ubx is efficient and requires no specialized equipment.
Bondos is studying how many proteins are amenable to fusion with Ubx. "It looks like it's a fairly wide range, and even though Ubx is positively charged, both positively and negatively charged proteins can be incorporated." She said even proteins that don't directly fuse with Ubx may be able to connect through intermediary binding partners.
Bondos said the 2009 paper "showed we could make three-dimensional scaffolds. We can basically make rods and sheets and meld them together; anything you can build with Legos, we can build with Ubx."
Ubx-based materials can match the natural properties of elastin, the protein that makes skin and other tissues pliable, Bondos said. "You don't want to make a heart out of something hard, and you don't want to make a bone out of something soft," she said. "We can tune the mechanical properties by changing the diameter of the fibers."
She said functionalized Ubx offers a path to growing three-dimensional organs layer by layer. "We should be able to build something shaped like a heart, and because we can pattern the chimeras within fibers and films, we can build instructions into the material that cause cells to differentiate as muscle, nerves, vasculature and other things."
Bondos suggested the material might also be useful for replacing damaged nerves. "We should be able to stimulate cell attachment and nerve growth along the middle and factors on the ends to enhance attachment to existing nerve cells, to tie it into the patient. It really is pretty exciting."
Matthews said the ability to characterize and pattern fibers for different functions should find many uses, because enzymes, antibodies, growth factors and peptide recognition sequences can now be incorporated into biomaterials. She said sequential arrays of functional fibers for step-by-step catalysis of materials is also possible.
"You're only limited by your mechanical imagination," she said.
The Robert A. Welch Foundation and Texas A&M Health Science Center Research Development and Enhancement Awards Program supported the research.
Zhao Huang, Taha Salim, Autumn Brawley, Jan Patterson, Kathleen S. Matthews, Sarah E. Bondos. Functionalization and Patterning of Protein-Based Materials Using Active Ultrabithorax Chimeras. Advanced Functional Materials, 2011; DOI: 10.1002/adfm.201100067
The advance, featured this week in the early online edition of the journal Proceedings of the National Academy of Sciences, represents the first demonstration of lens-free optical tomographic imaging on a chip, a technique capable of producing high-resolution 3-D images of large volumes of microscopic objects.
"This research clearly shows the potential of lens-free computational microscopy," said Aydogan Ozcan, senior author of the research and an associate professor of electrical engineering at UCLA's Henry Samueli School of Engineering and Applied Science. "Wonderful progress has been made in recent years to miniaturize life-sciences tools with microfluidic and lab-on-a-chip technologies, but until now optical microscopy has not kept pace with the miniaturization trend."
An optical imaging system small enough to fit onto an opto-electronic chip provides a variety of benefits. Because of the automation involved in on-chip systems, scientific work could be sped up significantly, which might have a great impact in the fields of cell and developmental biology. In addition, the small size not only has great potential for miniaturizing systems but also leads to cost savings on equipment.
The optical microscope, invented more than 400 years ago, has tended to grow larger and more complex as it has been modified to image ever-smaller objects with better resolution. To address this lack of progress in miniaturization, Ozcan's research group — with graduate student Serhan Isikman and postdoctoral scholar Waheb Bishara as lead researchers — developed the new tomographic microscopy platform through the next evolution of a lens-free imaging technology the group created and has been improving for years.
Ozcan, a researcher at the California NanoSystems Institute at UCLA, makes the analogy that a traditional optical microscope is like a huge set of pipes delivering content, in the form of images, to the user. Over years of development, bottlenecks occur that impede further improvement. Even if one part of the system — that is, one bottleneck — is improved, other bottlenecks keep that improvement from being fully realized. Not so with the lens-free system, according to Ozcan.
"Lens-free imaging removes the pipes altogether by utilizing an entirely new design," he said.
The system takes advantage of the fact that organic structures, such as cells, are partially transparent. So by shining a light on a sample of cells, the shadows created reveal not only the cells' outlines but details about their sub-cellular structures as well.
"These details can be captured and analyzed if the shadow is directed onto a digital sensor array," Isikman said. "The end result of this process is an image taken without using a lens."
Ozcan envisions this lens-free imaging system as one component in a lab-on-a-chip platform. It could potentially fit beneath a microfluidic chip, a tool for the precise control and manipulation of sub-millimeter biological samples and fluids, and the two tools would operate in tandem, with the microfluidic chip depositing and subsequently removing a sample from the lens-free imager in an automated, or high-throughput, process.
The platform's 3-D images are created by rotating the light source to illuminate the samples from multiple angles. These multiple angles also allow the system to utilize tomography, a powerful imaging technique. Through the use of tomography, the system is able to produce 3-D images without sacrificing resolution.
"The field of view of lens-based microscopes is limited because the lens focuses on a narrow area of a sample," Bishara said. "A lens-free microscope has both a much larger field of view and depth of field because the imaging is done by the digital sensor array and is not constrained by a lens."
Viewers, for instance, can use the system to focus in on the details of a booth within a panorama of a carnival midway, but also reverse time to see how the booth was constructed. Or they can watch a group of plants sprout, grow and flower, shifting perspective to watch some plants move wildly as they grow while others get eaten by caterpillars. Or, they can view a computer simulation of the early universe, watching as gravity works across 600 million light-years to condense matter into filaments and finally into stars that can be seen by zooming in for a close up.
"With GigaPan Time Machine, you can simultaneously explore space and time at extremely high resolutions," said Illah Nourbakhsh, associate professor of robotics and head of the CREATE Lab. "Science has always been about narrowing your point of view — selecting a particular experiment or observation that you think might provide insight. But this system enables what we call exhaustive science, capturing huge amounts of data that can then be explored in amazing ways."
The system is an extension of the GigaPan technology developed by the CREATE Lab and NASA, which can capture a mosaic of hundreds or thousands of digital pictures and stitch those frames into a panorama that be interactively explored via computer. To extend GigaPan into the time dimension, image mosaics are repeatedly captured at set intervals, and then stitched across both space and time to create a video in which each frame can be hundreds of millions, or even billions of pixels.
An enabling technology for time-lapse GigaPans is a feature of the HTML5 language that has been incorporated into such browsers as Google's Chrome and Apple's Safari. HTML5, the latest revision of the HyperText Markup Language (HTML) standard that is at the core of the Internet, makes browsers capable of presenting video content without use of plug-ins such as Adobe Flash or Quicktime.
Using HTML5, CREATE Lab computer scientists Randy Sargent, Chris Bartley and Paul Dille developed algorithms and software architecture that make it possible to shift seamlessly from one video portion to another as viewers zoom in and out of Time Machine imagery. To keep bandwidth manageable, the GigaPan site streams only those video fragments that pertain to the segment and/or time frame being viewed.
"We were crashing the browsers early on," Sargent recalled. "We're really pushing the browser technology to the limits."
Guidelines on how individuals can capture time-lapse images using GigaPan cameras are included on the site created for hosting the new imagery's large data files, http://timemachine.gigapan.org/wiki/Main_Page . Sargent explained the CREATE Lab is eager to work with people who want to capture Time Machine imagery with GigaPan, or use the visualization technology for other applications.
Once a Time Machine GigaPan has been created, viewers can annotate and save their explorations of it in the form of video "Time Warps."
Though the time-lapse mode is an extension of the original GigaPan concept, scientists already are applying the visualization techniques to other types of Big Data. Carnegie Mellon's Bruce and Astrid McWilliams Center for Cosmology, for instance, has used it to visualize a simulation of the early universe performed at the Pittsburgh Supercomputing Center by Tiziana Di Matteo, associate professor of physics.
"Simulations are a huge bunch of numbers, ugly numbers," Di Matteo said. "Visualizing even a portion of a simulation requires a huge amount of computing itself." Visualization of these large data sets is crucial to the science, however. "Discoveries often come from just looking at it," she explained.
Rupert Croft, associate professor of physics, said cosmological simulations are so massive that only a segment can be visualized at a time using usual techniques. Yet whatever is happening within that segment is being affected by forces elsewhere in the simulation that cannot be readily accessed. By converting the entire simulation into a time-lapse GigaPan, however, Croft and his Ph.D. student, Yu Feng, were able to create an image that provided both the big picture of what was happening in the early universe and the ability to look in detail at any region of interest.
Using a conventional GigaPan camera, Janet Steven, an assistant professor of biology at Sweet Briar College in Virginia, has created time-lapse imagery of rapid-growing brassicas, known as Wisconsin Fast Plants. "This is such an incredible tool for plant biology," she said. "It gives you the advantage of observing individual plants, groups of plants and parts of plants, all at once."
Steven, who has received GigaPan training through the Fine Outreach for Science program, said time-lapse photography has long been used in biology, but the GigaPan technology makes it possible to observe a number of plants in detail without having separate cameras for each plant. Even as one plant is studied in detail, it's possible to also see what neighboring plants are doing and how that might affect the subject plant, she added.
Steven said creating time-lapse GigaPans of entire landscapes could be a powerful tool for studying seasonal change in plants and ecosystems, an area of increasing interest for understanding climate change. Time-lapse GigaPan imagery of biological experiments also could be an educational tool, allowing students to make independent observations and develop their own hypotheses.
Source: PhysOrg - Provided by Carnegie Mellon University
Concrete pavements are made by mixing cement with water, sand, and "virgin aggregates" obtained from rock quarries located in the proximity of the construction site. In Indiana most of these aggregates are quarried limestone.
"Some parts of Indiana have plenty of quarries near highway construction sites," said Nancy Whiting, a scientist with the Applied Concrete Research Initiative at Purdue's School of Civil Engineering. "In other places, it's more difficult to find quality aggregate. If you have to drive 50 or 100 miles to get a good quality aggregate, it's going to be much more cost effective to use recycled materials by crushing the concrete you have in place."
Whiting is leading the concrete recycling project funded by INDOT through the Joint Transportation Research Program with Jan Olek, a Purdue professor of civil engineering, postdoctoral research associate Jitendra Jain and graduate research assistant Kho Pin Verian.
"If you are going to pave, you may have to remove the old concrete and break it into pieces anyway, so recycling makes sense," Olek said. "And you avoid putting it in landfills."
Jain gave a research presentation about the work earlier this month during a meeting of the American Concrete Institute in Tampa, Fla.
The researchers are testing concrete mixtures that contain varying percentages of recycled concrete. They also are developing cost-analysis software that will enable the state and construction contractors to estimate how much they could save by using recycled concrete. Crushing old concrete pavements into aggregate that can be recycled in new concrete can potentially reduce materials costs by 10 percent to 20 percent, depending on whether any quarries are located near construction sites.
"Whether that would mean a comparable reduction in overall construction costs is part of what our research will determine," Whiting said.
Also involved in the work are Mark Snyder, an engineering consultant based in Pittsburgh, and Tommy Nantung, a project administrator at INDOT. Indiana currently allows the use of "recycled concrete as aggregate," or RCA, as a base layer to support new pavements. However, no existing specifications allow for use of this material in new concrete mixtures. The goal of the research project is to extend the use of the crushed concrete for manufacturing of mixtures that can be used to construct the pavement itself.
The team will finalize a report early next year, providing guidelines and recommendations to help create design and material standards. Standards are needed to control the quality of RCA and its proper use in creating the new concrete.
"Various other states have used crushed concrete as aggregate, but there has been no standardization, so the end result hasn't always been good," Whiting said. "We are trying to show INDOT that it can work and how to be consistent about getting a good product."
One aim is to ensure resistance of the RCA to cracking due to freezing and thawing cycles the pavements are exposed to during winter. Some aggregates are more susceptible to cracking than others. The focus of the standards will be on test methods for freeze-thaw durability and absorption of water and deicing chemicals.
The researchers are working with industry to produce nearly 400 test specimens of varying sizes and shapes containing different percentages of recycled aggregate. Concrete taken from State Route 26 when it was recently repaved in Lafayette has been crushed for use as RCA for the project.
"Slabs of concrete have been crushed into aggregate by Milestone Contractors LP under the direction of J. Beland," said Whiting.
A commercial concrete plant in Lafayette operated by Irving Materials Inc. is mixing the material. In addition, Jay Snider and Calvin Kingery of Irving Materials as well as Dick Newell of Milestone Contractors are working alongside the researchers, helping with issues ranging from adjusting mixture proportions to placement of trial slabs in the field.
Industry partners helped found the Applied Concrete Research Initiative in 2008 along with INDOT and academia, and are providing their services free of charge.
"They are doing this as a courtesy to us," Olek said. "This type of collaboration with practitioners is critical with respect to implementation of laboratory derived materials and technologies in the field."
More information: Predicting Long Term Durability of Concretes with Recycled Concrete as Coarse Aggregates
The use of recycled concrete (RCA) as coarse aggregates in concrete is a sustainable, cost-effective alternative to disposing the old concrete pavements. Previous studies indicated that replacing up to 30% of the original (virgin) coarse aggregate in the mixture with RCA will have no negative effects on the freeze-thaw (F/T) resistance and mechanical properties of hardened concretes. In the present study, RCA was used in both plain and fly ash (20% of Class C fly ash) concretes to substitute for crushed limestone coarse virgin aggregates at four different replacement levels (0%, 30%, 50%, and 100%). The long-term durability of all concrete mixtures was evaluated by determining the F/T resistance (ASTM C666 procedure A), scaling resistance (ASTM C672), and rapid chloride penetration (RCP) resistance (ASTM C1202). In addition, the electrical impedance spectroscopy (EIS) measurements were performed on the same concrete specimens that were used for RCP test. EIS spectra were obtained using a Solartron™ 1260 gain-phase analyzer. A frequency range of 1 Hz–10 MHz using a 250 mV AC signal was employed, with 10 measurements per decade. The relationship between the values of final charge passed and bulk resistance obtained from EIS will be used to evaluate the effects of increase in temperature on charge passed during RCP for concretes with RCA. The different test results from this study would be useful to optimize the replacement levels as well as preferred tests to predict long-term durability of concretes with RCA.
Source: Physorg - Research Provided by Purdue University
Jack Kevorkian might be gone, but his spirit lives on -- well, maybe living isn't the best way to put it...
For the first time ever, this Friday night, a website will run a live broadcast of a terminally ill man ending his life in a case of assisted suicide.
Nikolai Ivanisovich, 62, is terminally ill with brain cancer. He will die before cameras and a worldwide audience at a clinic in Switzerland, with the use of lethal injection administered by a physician.
The filming of his death will be broadcast on BattleCam.com, a 24/7 Reality TV website where live events are regularly cast to a wide range of audiences.
The site is run by billionaire businessman Alki David, who purchased the exclusive rights to broadcast the process.
ALKI DAVID & NIKOLAI IVANISOVICH
"I am grateful to Mr. David and his team for making this possible," Ivanisovich told Russia Today. "My family will be able to live in prosperity after I pass. May God bless Mr. David for his kindness and generosity.
"Projecting the moral questions that will arise from this event, I would like to add that I find nothing wrong with this at all.
“Death is a fact of life... many governments throughout the western world, including Switzerland, Belgium and Luxembourg, recognize the importance the right to each individual's right to end their life, free of terminal pain."
The controversial event comes at a time the world is in the midst of a debate on assisted suicides: In the United States, it is legal only in the states of Oregon, Montana and Washington.
"This is a breakthrough in consciousness on what we watch,” BattleCam Operations VP Claude Haraser said, “and how we watch it."
In a paper published in Science, Los Alamos researchers Gang Wu, Christina Johnston, and Piotr Zelenay, joined by researcher Karren More of Oak Ridge National Laboratory, describe the use of a platinum-free catalyst in thecathode of a hydrogen fuel cell. Eliminating platinum—a precious metal more expensive than gold—would solve a significant economic challenge that has thwarted widespread use of large-scale hydrogen fuel cell systems.
Polymer-electrolyte hydrogen fuel cells convert hydrogen and oxygen into electricity. The cells can be enlarged and combined in series for high-power applications, including automobiles. Under optimal conditions, the hydrogen fuel cell produces water as a "waste" product and does not emit greenhouse gasses. However, because the use of platinum in catalysts is necessary to facilitate the reactions that produce electricity within a fuel cell, widespread use of fuel cells in common applications has been cost prohibitive. An increase in the demand for platinum-based catalysts could drive up the cost of platinum even higher than its current value of nearly $1,800 an ounce.
The Los Alamos researchers developed non-precious-metal catalysts for the part of the fuel cell that reacts with oxygen. The catalysts—which use carbon (partially derived from polyaniline in a high-temperature process), and inexpensive iron and cobalt instead of platinum—yielded high power output, good efficiency, and promising longevity. The researchers found that fuel cells containing the carbon-iron-cobalt catalyst synthesized by Wu not only generated currents comparable to the output of precious-metal-catalyst fuel cells, but held up favorably when cycled on and off—a condition that can damage inferior catalysts relatively quickly.
Moreover, the carbon-iron-cobalt catalyst fuel cells effectively completed the conversion of hydrogen and oxygen into water, rather than producing large amounts of undesirable hydrogen peroxide. Inefficient conversion of the fuels, which generates hydrogen peroxide, can reduce power output by up to 50 percent, and also has the potential to destroy fuel cell membranes. Fortunately, the carbon- iron-cobalt catalysts synthesized at Los Alamos create extremely small amounts of hydrogen peroxide, even when compared with state-of-the-art platinum-based oxygen-reduction catalysts.
Because of the successful performance of the new catalyst, the Los Alamos researchers have filed a patent for it.
"The encouraging point is that we have found a catalyst with a good durability and life cycle relative to platinum-based catalysts," said Zelenay, corresponding author for the paper. "For all intents and purposes, this is a zero-cost catalyst in comparison to platinum, so it directly addresses one of the main barriers to hydrogen fuel cells."
The next step in the team's research will be to better understand the mechanism underlying the carbon-iron-cobalt catalyst. Micrographic images of portions of the catalyst by researcher More have provided some insight into how it functions, but further work must be done to confirm theories by the research team. Such an understanding could lead to improvements in non-precious-metal catalysts, further increasing their efficiency and lifespan.
At first glance, the plans for the 10MW Tower have all the trappings of pre-crash Dubai: the improbable height, the flashy facade, the swagger of a newbie in a crowded skyline. On closer inspection, however, it’s an eco-machine. The A-shaped, 1,969-foot concept skyscraper is designed to turn out as much as 10 times the energy it needs, enough to power up to 4,000 nearby homes.
Dubai's 10MW Tower - Courtesy Robert Ferry/Studied Impact Design
Three separate systems make it work. First, a five-megawatt wind turbine in the hollow of the “A” generates energy in the powerful and unpredictable desert gusts. Second, mirrors dot the slanted, south-facing facade, beaming light to a molten-salt-filled collector that hangs off the building like an ultra-tall street lamp. Cooked to 932şF, the liquefied salt transfers heat to a convection loop that runs a three-megawatt steam turbine. Finally, a two-megawatt solar updraft tower produces additional energy in clear weather. Sunlight warms air in a two-foot-wide gap that runs the length of the southern face. The airflow from rising heat powers an internal wind turbine.
Reflective: The facade directs light to a power-producing salt-cooker. Courtesy Robert Ferry/Studied Impact Design
If it were built (at an estimated cost of $400 million), 10MW could pay off its energy debt in 20 years. Extra juice feeds the municipal grid, and other sources in the area would adjust for the tower’s output. The building could house offices or residences or both, says designer Robert Ferry, 35, who helms the Dubai architecture firm Studied Impact with his wife, Elizabeth Monoian. The pair became interested in energy-generating skyscrapers on moving to the United Arab Emirates, where there are superstructures in spades but few that are any greener than their brochures. With the 10MW Tower, they hope to someday create a power plant you can live in. It may sound fantastic, but, Ferry says, “it’s only a matter of time before something like this is built.”
Revolutionary: A five-megawatt turbine contributes to the building’s annual output of 20,000 megawatt-hours. Courtesy Robert Ferry/Studied Impact Design