The discovery of the link between electricity and magnetism less than two centuries ago had a profound impact on our world where electronic devices and electrical power are ubiquitous. But while engineers have harnessed electromagnetic forces on a global scale, physicists still struggle to describe the dance between electrons that creates magnetic fields.
Two theoretical physicists from Rice University are reporting initial success in that area in a paper published in the Proceedings of the National Academy of Science. Their new conceptual model, which was created to learn more about the quantum quirks of high-temperature superconductors and other high-tech materials, has also proven useful in describing the origins of ferromagnetism — the everyday “magnetism” of compass needles and refrigerator magnets.
The conference “Graphene Brazil 2010” will take place December 14-17 2010 in Belo Horizonte, Minas Gerais, Brazil. The aim of this conference is to bring leading scientists in the area of graphene science together to evaluate past and define future trends of this exciting field. The conference will address progress at the frontiers of fundamental as well as applied research and will allow participants to exchange ideas and results of their latest work in an informal atmosphere.
Imagine a device the size of a grain of sand which is capable of analyzing the environment around it, recognize its chemical composition, and report it to a monitoring system. This is the concept of nanotechnology-based electronic noses (e-nose) – miniature electronic devices which mimic the olfactory systems of mammals and insects.
An international team of researchers has made a further step towards this vision and demonstrated a novel analytical sensor which mimics our olfaction system. The difference between this and similar prior e-noses is that the active element of this new device is an individual wedge-like nanowire (nanobelt) made of tin dioxide. The required diversity of the sensing elements is encoded in the nanobelt morphology via longitudinal width variations of the nanobelt realized during its growth and via functionalization of some of the segments with palladium catalyst. “Our approach demonstrates the potential of combining bottom-up nanowire fabrication protocols with state-of-the art microfabrication methods to design prospective simple sensing arrays which, in principle, might be scaled down to the size of few micrometers and thus become the smallest analytical instrument,” tells Andrei Kolmakov, an associate professor in the physics department at Southern Illinois University at Carbondale.
Kolmakov and a team of researchers from Karlsruhe Institute of Technology, Rensselaer Polytechnic Institute, Sincrotrone Trieste, and first author Victor V. Sysoev from Saratov State Technical University, have published their findings in ACS Nano. In what probably is the simplest and yet fully functioning e-nose, the device is made of an individual single-crystal metal oxide quasi-1D nanobelt. The nanobelt was indexed with a number of platinum electrodes in a way that each segment of the nanobelt between two electrodes defines an individual sensing elemental receptor of the array.
The main obstacle to building a ‘hydrogen economy’ – this much touted vision of a society where the main energy carrier is hydrogen – is the lack of efficient hydrogen storage. The research conducted in the hydrogen storage scientific community is aimed towards mobile applications. Hydrogen is a gas at ambient conditions and takes up a lot of space. For stationary storage facilities, for which available space is not an issue, hydrogen gas can be kept in large tanks at moderate pressures using already known technology. However, in order to utilize hydrogen for mobile applications i.e. to produce and be able to sell hydrogen fuelled cars on a large scale, it must be stored in a compact, safe, cheap and efficient way.
In 2009, the U.S Department of Energy (DOE) proposed on-board hydrogen storage system performance targets that have become widely accepted. So far, researchers haven’t been able to successfully demonstrate a material that is capable of simultaneously meeting all of the requirements and criteria set out by the DOE.
A European research team has now reported on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. They demonstrate that nanoconfined hydride has a significant hydrogen storage potential. Research at the Nano Energy-Materials research group at Interdisciplinary Nanoscience Center (iNANO) at Aarhus University in Denmark, led by Flemming Besenbacher and Torben R. Jensen, focuses on the utilization of nanoporous materials as scaffolds for preparation and confinement of nanosized metal hydrides. This bottom-up approach limits the particle size of the hydride to the average pore size of the scaffold material, which allows for the direct production of smaller particles than obtainable mechanically. Furthermore, particle growth and agglomeration may be hindered by the compartmentalization of the nanoparticles within the scaffold material. Nanoconfinement may also mediate improved re-hydrogenation properties of complex metal hydrides.
Scientists have made a breakthrough toward creating nanocircuitry on graphene, widely regarded as the most promising candidate to replace silicon as the building block of transistors. They have devised a simple and quick one-step process based on thermochemical nanolithography (TCNL) for creating nanowires, tuning the electronic properties of reduced graphene oxide on the nanoscale and thereby allowing it to switch from being an insulating material to a conducting material.
The technique works with multiple forms of graphene and is poised to become an important finding for the development of graphene electronics. The research is published in the Science journal. Scientists who work with nanocircuits are enthusiastic about graphene because electrons meet with less resistance when they travel along graphene compared to silicon and because today’s silicon transistors are nearly as small as allowed by the laws of physics. Graphene also has the edge due to its thickness – it’s a carbon sheet that is a single atom thick. While graphene nanoelectronics could be faster and consume less power than silicon, no one knew how to produce graphene nanostructures on such a reproducible or scalable method. That is until now.
Researchers at the University of Iceland, University of Cologne and the Fraunhofer Institute Jena have demonstrated net optical amplification in a plasmonic waveguide. The results of the team, which were published in the journal Nature Photonics, represent an important breakthrough in the field of plasmonics. Optical amplification is the only feasible strategy to make light travel over sizable distances when it is bound in a plasmonic mode. Achieving such a macroscopic propagation of surface plasma waves is critical for many applications of the emerging plasmonics technology, which range from compact communication devices and optical computing to the detection and characterization of cells, virus particles or even single molecules.
A surface plasmon is a collective excitation involving all conducting electrons in a metallic layer moving relatively to the static positive ions of the metal as shown in the diagram. Research on plasmonics, a relatively new branch of optics, has received an increasing level of international attention over the last decade. This interest is mainly driven by the fact that surface plasmons, travelling along the interface between a metal and a dielectric, allow confining optical energy to volumes that are significantly smaller than those accessible with conventional dielectric waveguiding structures such as optical fibers.
I obtained a degree in physics engineering at École Polytechnique de Montréal in May 2001. I immediately started my master’s degree at INRS Energy and Materials. My research subject was the numerical simulation of hydrogen adsorption in carbon nanostructures. I finished my research on this subject in March 2003. After completing my studies, I chose to reorient my career toward IT systems engineering. Computing has been a passion for me since the age of 13. My interest for this field grew when I discovered the Linux operating system ten years ago. Rather than being forced to spend money for testing new network configurations and server software, I was free to do it with Linux, a minimal hardware setup and a lot of hours reading available documentation. I definitely appreciate the community spirit of the OpenSource movement. Sharing experience and knowledge has lead to great innovations for the whole IT industry.
The future of clean green solar power may well hinge on scientists being able to unravel the mysteries of photosynthesis, the process by which green plants convert sunlight into electrochemical energy. To this end, researchers at the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) have recorded the first observation and characterization of a critical physical phenomenon behind photosynthesis known as quantum entanglement.
Previous experiments led by Graham Fleming, a physical chemist, pointed to quantum mechanical effects as the key to the ability of green plants, through photosynthesis, to almost instantaneously transfer solar energy from molecules in light harvesting complexes to molecules in electrochemical reaction centres. Now a new collaborative team that includes Fleming have identified entanglement as a natural feature of these quantum effects. Their work is published in the Nature Physics journal. When two quantum-sized particles, for example a pair of electrons, are entangled, any change to one will be instantly reflected in the other, no matter how far apart they might be. Though physically separated, the two particles act as a single entity.
The recent emergence of graphene has generated a world-wide – and highly competitive – scientific enthusiasm, due to the extraordinary properties which are expected from graphene-based nano-objects and their derivatives. Its structural and chemical simplicity makes graphene a very convenient systems for fundamental research and for the development of nano-scale sciences. On the other hand, the numerous variations of the graphene based nano-objects allow a unique variability of properties (transport, mechanical, optical, chemical…) and an unusually high number of potential applications, spanning energy, nanoelectronics, or chemical industry. Graphene is also ideal for chemists who can modify its properties by functionalisation, grafting, adsorption and doping. Investigating graphene clearly requires the involvement of scientists in areas related to physics, chemistry, and materials sciences.
This growing interest, triggered by the numerous potential applications of graphene in future nanotechnology, motivates the creation of an interdisciplinary school on graphene. The school is aimed at PhD students, post-doctoral and young researchers in the first instance. The School is taking place in Cargèse, France from October 12 to October 22, 2010 at the Institut d’Etudes Scientifiques de Cargèse.
In a groundbreaking series of experiments, scientists in the United States managed to develop a new method of analyzing how graphene sheets are stacked on top of each other. The technique is also suitable for determining which areas of the compound are subjected to most strain, when the material is placed inside more complex structures. All of this can be inferred using moire patterns, which are interference patterns that appear at an atomic scale, when two layers of atoms are placed on top of each other imperfectly, as in slightly askew (image courtesy of NIST).
The research team that conducted the new investigation features physicists from the US National Institutes of Standards and Technology (NIST) and the Georgia Institute of Technology (Georgia Tech). The experts say that the moire patterns can also be used on multiple grids or atom arrays, not only on two. They add that using “atomic moire interferometry” can also help scientists determine the rotational orientation of the graphene sheets used in a variety of technological applications. Their work is published in the Physical Review B journal.