From allowing our eyes to see, to enabling green plants to harvest energy from the sun, photochemical reactions – reactions triggered by light – are both ubiquitous and critical to nature. Photochemical reactions also play essential roles in high technology, from the creation of new nanomaterials to the development of more efficient solar energy systems. Using photochemical reactions to our best advantage requires a deep understanding of the interplay between the electrons and atomic nuclei within a molecular system after that system has been excited by light. A major advance towards acquiring this knowledge has been reported by a team of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. Graham Fleming, UC Berkeley’s Vice Chancellor for Research, a faculty senior scientist with Berkeley Lab’s Physical Biosciences Division, and member of the Kavli Energy NanoSciences Institute at Berkeley, led the development of a new experimental technique called two-dimensional electronic-vibrational spectroscopy (2D-EV). By combining the advantages of two well-established spectroscopy technologies – 2D-electronic and 2D-infrared – this technique is the first that can be used to simultaneously monitor electronic and molecular dynamics on a femtosecond (millionth of a billionth
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In 2008, scientists at HP invented a fourth fundamental component to join the resistor, capacitor, and inductor: the memristor. Theorized back in 1971, memristors showed promise in computing as they can be used to both build logic gates, the building blocks of processors, and also act as long-term storage.
At its HP Discover conference in Las Vegas today, HP announced an ambitious plan to use memristors to build a system, called simply "The Machine," shipping as soon as the end of the decade. By 2016, the company plans to have memristor-based DIMMs, which will combine the high storage densities of hard disks with the high performance of traditional DRAM.
John Sontag, vice president of HP Systems Research, said that The Machine would use "electrons for processing, photons for communication, and ions for storage." The electrons are found in conventional silicon processors, and the ions are found in the memristors. The photons are because the company wants to use optical interconnects in the system, built using silicon photonics technology. With silicon photonics, photons are generated on, and travel through, "circuits" etched onto silicon chips, enabling conventional chip manufacturing to construct optical parts. This allows the parts of the system using photons to be tightly integrated with the parts using electrons.
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Researchers used quantum theory – usually invoked to describe the actions of subatomic particles – to identify an unexpected and strange pattern in how people respond to survey questions. By conventional standards, the results are surprising: The scientists found the exact same pattern in 70 nationally representative surveys from Gallup and the Pew Research center taken from 2001 to 2011, as well as in two laboratory experiments. Most of the national surveys included more than 1,000 respondents in the United States. “Human behavior is very sensitive to context. It may be as context sensitive as the actions of some of the particles that quantum physicists study,” said Zheng Wang, lead author of the study and associate professor of communication at The Ohio State University. “By using quantum theory, we were able to predict a surprising regularity in human behavior with unusual accuracy for the social sciences in a large set of different surveys.” The study appears online in the Proceedings of the National Academy of Sciences. Wang conducted the study with Tyler Solloway of Ohio State, and Richard Shiffrin and Jerome Busemeyer of Indiana University. These new findings involved an issue that has long faced researchers using survey data or any
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ESA’s Rosetta spacecraft has found that comet 67P/Churyumov–Gerasimenko is releasing the equivalent of two small glasses of water into space every second, even at a cold 583 million kilometres from the Sun.
Last week was marked by Graphene Week 2014, one of the largest graphene events. This year, the conference was hosted at Chalmers University of Technology in Gothenburg by the Graphene Flagship. With 450 participants, the conference was sold out.
Bringing together an impressive list of speakers, the meeting addressed fundamental studies of graphene and related two-dimensional materials, applications of graphene and 2D materials in electronics, photonics, spintronics, and sensing, applications of graphene in energy, including photovoltaics, energy storage, fuel cells and hydrogen storage, large scale graphene production, graphene-based composite materials, graphene-related health and environment research, and applications of graphene in biomedical solutions.
Some of the flagship work package leaders were on site, describing the aim and progress of their section of the billion-euro project. For example, Herre van der Zant of TU Delft talked about the work package “Sensors”, in which the industry sees great potential. Graphene can be made into a good sensor by exploiting any of its remarkable properties. For example the fact that the material is very thin allows for a large surface-to-volume ratio, enhancing sensitivity to trace chemicals.
The conference also hosted representatives of scientific journals, who scouted the progress of the field and learned about the flagship effort. Editors of Physical Review Letters, three journals of the Nature family, and the journal 2D Materials, gave tips on how to publish scientific research in their magazines.
Photo: Chalmers / Henrik Sandsjö
As part of the dissemination effort of the flagship programme, an exhibition about graphene was opened on the second day of the conference in the Science Center Universeum, which attracts more than half a million visitors yearly. The exhibition aims to educate the general public about the prospects of graphene, and about the flagship effort.
Also coinciding with the conference came the announcement of new admissions to the flagship, which doubled the size of the consortium. 66 new partners were invited to participate in the project, following a 9-million euro competitive call. The competition was fierce – less than 10% of the submitted proposals were accepted.
On our behalf, Amaia Zurutuza gave an invited talk on recent advances in graphene applications, Alba Centeno contributed a talk about graphene-reinforced ceramics, while Amaia Pesquera presented a poster on the latest results in transmission electron microscopy of graphene.
The Graphene Flagship certainly did an amazing job organizing the conference and the exhibition, and we are proud to be an integral part of the flagship effort as the largest supplier of graphene on board. We extend our congratulations to the organization and look forward to the many events in the next 9 years.
Submicroscopic particles that contain even smaller particles of iron oxide could make magnetic resonance imaging (MRI) a far more powerful tool to detect and fight disease. Silicon mesoporous particles, aka SiMPS, about 1,000 nanometers across contain thousands of much smaller particles of iron oxide. The SiMPs can be manipulated by magnets and gather at the site of tumors, where they can be heated to kill malignant tumors or trigger the release of drugs. The particles were created by an international team led by scientists at Rice University and The Methodist Hospital Research Institute in Houston. Courtesy of the Wilson Group Scientists at Rice University and The Methodist Hospital Research Institute (TMHRI) led an international team of researchers in creating composite particles that can be injected into patients and guided by magnetic fields. Once in position, the particles may be heated to kill malignant tissues or trigger the release of drugs at the site. The “nanoconstructs” should fully degrade and leave the body within a few days, they reported. The research appears online in the journal Advanced Functional Materials. The team led by Rice chemist Lon Wilson and TMHRI scientist Paolo Decuzzi was searching for a way to overcome the challenges presented
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Using miniaturized laser technology, a tiny sensor has been built at the Vienna University of Technology which can test the chemical composition of liquids. They are invisible, but perfectly suited for analysing liquids and gases; infrared laser beams are absorbed differently by different molecules. This effect can for instance be used to measure the oxygen concentration in blood. At the Vienna University of Technology, this technique has now been miniaturized and implemented in the prototype for a new kind of sensor. Just a drop is enough to test the chemical composition. Specially designed quantum cascade lasers and light detectors are created by the same production process. The gap between laser and detector is only 50 micrometres. It is bridged by a plasmonic waveguide made of gold and silicon nitride. This new approach allows for the simple and cheap production of tiny sensors for many different applications. Laser and Detector Simple solid-state lasers, such as the well-known red ruby laser, consist of only one material. Quantum cascade lasers, on the other hand, are made of a perfectly optimized layer system of different materials. That way, the properties such as the wavelength of the laser can be tuned. When a voltage is
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Enrico Fermi, when asked about intelligent life on other planets, famously replied, “Where are they?” Any civilization advanced enough to undertake interstellar travel would, he argued, in a brief period of cosmic time, populate its entire galaxy. Yet, we haven’t made any contact with such life. This has become the famous "Fermi Paradox.”
Various explanations for why we don’t see aliens have been proposed—perhaps interstellar travel is impossible or maybe civilizations are always self-destructive. But with every new discovery of a potentially habitable planet, the Fermi Paradox becomes increasingly mysterious. There could be hundreds of millions of potentially habitable worlds in the Milky Way alone.
This impression is only reinforced by the recent discovery of a “Mega-Earth," a rocky planet 17 times more massive than the Earth but with only a thin atmosphere. Previously, it was thought that worlds this large would hold onto an atmosphere so thick that their surfaces would experience uninhabitable temperatures and pressures. But if this isn’t true, there is a whole new category of potentially habitable real estate in the cosmos.
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Nanopores could provide a new way to sequence DNA quickly, but the physics involved isn’t well understood. That’s partly because of the complexities involved in studying the random, squiggly form DNA takes in solution. Researchers from Brown have simplified matters by using a stiff, rod-like virus instead of DNA to experiment with nanopores. Their research has uncovered previously unknown dynamics in polymer-nanopore interactions. Nanopores may one day lead a revolution in DNA sequencing. By sliding DNA molecules one at a time through tiny holes in a thin membrane, it may be possible to decode long stretches of DNA at lightning speeds. Scientists, however, haven’t quite figured out the physics of how polymer strands like DNA interact with nanopores. Now, with the help of a particular type of virus, researchers from Brown University have shed new light on this nanoscale physics. “What got us interested in this was that everybody in the field studied DNA and developed models for how they interact with nanopores,” said Derek Stein, associate professor of physics and engineering at Brown who directed the research. “But even the most basic things you would hope models would predict starting from the basic properties of DNA — you couldn’t
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Brookhaven physicist Oleg Gang and Stony Brook University postdoctoral researcher Sunita Srivastava Scientists seeking ways to engineer the assembly of tiny particles measuring just billionths of a meter have achieved a new first—the formation of a single layer of nanoparticles on a liquid surface where the properties of the layer can be easily switched. Understanding the assembly of such nanostructured thin films could lead to the design of new kinds of filters or membranes with a variable mechanical response for a wide range of applications. In addition, because the scientists used tiny synthetic strands of DNA to hold the nanoparticles together, the study also offers insight into the mechanism of interactions of nanoparticles and DNA molecules near a lipid membrane. This understanding could inform the emerging use of nanoparticles as vehicles for delivering genes across cellular membranes. “Many of the applications we envision for nano particles … require planar geometry. Using DNA linker molecules gives us a way to control the interactions between the nanoparticles.” — Sunita Srivastava “Our work reveals how DNA-coated nanoparticles interact and re-organize at a lipid interface, and how that process affects the properties of a “thin film” made of DNA-linked nanoparticles,” said physicist Oleg Gang
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The days of self-assembling nanoparticles taking hours to form a film over a microscopic-sized wafer are over. Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have devised a technique whereby self-assembling nanoparticle arrays can form a highly ordered thin film over macroscopic distances in one minute. Upon solvent annealing, supramolecules made from gold nanoparticles and block copolymers will self-assemble into highly ordered thin films in one minute. Ting Xu, a polymer scientist with Berkeley Lab’s Materials Sciences Division, led a study in which supramolecules based on block copolymers were combined with gold nanoparticles to create nanocomposites that under solvent annealing quickly self-assembled into hierarchically-structured thin films spanning an area of several square centimeters. The technique is compatible with current nanomanufacturing processes and has the potential to generate new families of optical coatings for applications in a wide number of areas including solar energy, nanoelectronics and computer memory storage. This technique could even open new avenues to the fabrication of metamaterials, artificial nanoconstructs that possess remarkable optical properties. Ting Xu holds joint appointments with Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Departments of Materials Sciences and Engineering, and Chemistry. (Photo by Roy Kaltschmidt) “Our
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Orion's belt runs just along the horizon, seen through Earth's atmosphere and rising in this starry snapshot from low Earth orbit on board the International Space Station. The belt stars, Alnitak, Alnilam, and Mintaka run right to left and Orion's sword, home to the great Orion Nebula, hangs above his belt, an orientation unfamiliar to denizens of the planet's northern hemisphere. That puts bright star Rigel, at the foot of Orion, still higher above Orion's belt. Of course the brightest celestial beacon in the frame is Sirius, alpha star of the constellation Canis Major. The station's Destiny Laboratory module is in the foreground at the top right.Rice graduate student Sehmus Ozden holds a carbon nanotube forest. Ozden treated nanotube arrays to harvest water in the same way beetles do in the desert, by combining hydrophilic and hydrophobic surfaces. Photo by Jeff Fitlow If you don’t want to die of thirst in the desert, be like the beetle. Or have a nanotube cup handy. New research by scientists at Rice University demonstrated that forests of carbon nanotubes can be made to harvest water molecules from arid desert air and store them for future use. The invention they call a “hygroscopic scaffold” is detailed in a new paper in the American Chemical Society journal Applied Materials and Interfaces. Researchers in the lab of Rice materials scientist Pulickel Ajayan found a way to mimic the Stenocara beetle, which survives in the desert by stretching its wings to capture and drink water molecules from the early morning fog. Electron microscope images show the superhydrophobic (water-repelling) side (top) of a hygroscopic scaffold created at Rice University. The bottom image shows the hydrophilic (water-loving) side.They modified carbon nanotube forests grown through a process created at Rice, giving the nanotubes a superhydrophobic (water-repelling) bottom and a hydrophilic (water loving) top. The forest attracts water molecules from the air
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A new cost-effective technology to treat mining wastewater and reduce sludge by up to 90 per cent has been used for the first time at a commercial mine. The technology, called Virtual Curtain, was used to remove metal contaminants from wastewater at a Queensland mine and the equivalent of around 20 Olympic swimming pools of rainwater-quality water was safely discharged. Sludge is a semi-solid by-product of wastewater treatment and reducing the amount produced has huge environmental and economic benefits. “Our treatment produced only a fraction of the sludge that a conventional lime-based method would have and allowed the mine water to be treated in a more environmentally sound way,” CSIRO scientist Dr Grant Douglas said. “Reducing the amount of sludge is beneficial because the costly and timely steps involved to move and dispose it can be reduced.” Given the Australian mining industry is estimated to generate hundreds of millions of tonnes of wastewater each year, the technology opens a significant opportunity for companies to improve water management practices and be more sustainable. “The technology can produce a material high in metal value, which can be reprocessed to increase a miner’s overall recovery rate and partially offset treatment costs,” Dr Douglas
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