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A multi-university team of researchers has artificially engineered a unique multilayer material that could lead to breakthroughs in both superconductivity research and in real-world applications. The researchers can tailor the material, which seamlessly alternates between metal and oxide layers, to achieve extraordinary superconducting properties - in particular, the ability to transport much more electrical current than non-engineered materials. The team includes experts from the Univ. of Wisconsin-Madison, Florida State Univ. and the Univ. of Michigan. The group described its breakthrough March 3, 2013, in the advance online edition of the journal Nature Materials. The researchers’ new material is composed of 24 layers that alternate between the pnictide superconductor and a layer of the oxide strontium titanate. The researchers maintained an atomically sharp interface. The new material also has improved current-carrying capabilities. As they grew the superlattice, the researchers also added a tiny bit of oxygen to intentionally insert defects every few nanometers in the material. These defects act as pinning centers to immobilize tiny magnetic vortices that, as they grow in strength in large magnetic fields, can limit current flow through the superconductor.
(Ars Technica) A group of researchers in Germany who have a history of working with lithium-air batteries have turned their attention to sodium-air. The reason for the change is that lithium-air has some unfortunate chemistry that has proven difficult to overcome. The researchers wanted a simpler system that might not have as many technical hurdles. It turns out that sodium-air provides this system. The battery they constructed is very simple. There’s a solid sodium electrode at one end. On top of that an electrolyte is placed, then an air-permeable carbon electrode. The metal atoms release an electron that travels through a circuit to do work while the ionic form of the metal dissolves into the electrolyte and travels to the carbon electrode. At that electrode it combines with oxygen and an electron to form sodium oxide. It’s important to remember that this is very much exploratory, so the news is quite mixed. It certainly can’t compare with a commercial lithium-ion battery, but it compares very well with lithium-air. The researchers found that it was easier to charge, held more charge, and had better discharge characteristics. In other words, even though lithium-air has a higher theoretical energy density, sodium-air has a higher practical energy density. Further, that energy is stored in the battery more efficiently and can be extracted more efficiently.
The adsorption of ions in microporous materials governs the operation of technologies as diverse as water desalination, energy storage, sensing, and mechanical actuation. Until now, however, researchers attempting to improve the performance of these technologies haven’t been able to directly and unambiguously identify how factors such as pore size, pore surface chemistry and electrolyte properties affect the concentration of ions in these materials as a function of the applied potential. To provide the needed information, researchers at the Georgia Institute of Technology and the Oak Ridge National Laboratory have demonstrated that a technique known as small angle neutron scattering (SANS) can be used to study the effects of ions moving into nanoscale pores. Believed to be the first application of the SANS technique for studying ion surface adsorption in-situ, details of the research were reported recently in Angewandte Chemie International Edition. Using conductive nanoporous carbon, the researchers conducted proof-of-concept experiments to measure changes in the adsorption of hydrogen ions in pores of different sizes within the same material due to variations in solvent properties and applied electrical potential. Systematic studies performed with such a technique could ultimately help identify the optimal pore size, surface chemistry and electrolyte solvent properties necessary for either maximizing or minimizing the adsorption of ions under varying conditions
When a crystal is hit by an intense ultrashort light pulse, its atomic structure is set in motion. A team of scientists from the Max Planck Institute of Quantum Optics, the Technischen Universität München, the Fritz-Haber Institute in Berlin, and the Universität Kassel can now observe how the configuration of electrons and atoms in titanium dioxide, a semiconductor, changes under the impact of an ultraviolet laser pulse, confirming that even subtle changes in the electron distribution caused by the excitation can have a considerable impact on the whole crystal structure. The physicists illuminated a titanium dioxide crystal with an intense ultraviolet laser pulse of less than five femtoseconds duration. The laser pulse excites the valence electrons in the crystal and generates a small number of hot electrons with a temperature of several thousand Kelvin. Following the first, intense laser pulse, the changes in the reflectivity of the crystal on the femtosecond timescale were observed by a second, weak light pulse. This measurement provides the scientists with information on the changes in the crystal induced by the first laser pulse: the intense ultraviolet laser pulse did not only heat up the valence electrons but also changed the electron distribution within the lattice.
A white Hyundai ix35 Fuel Cell (PEM-type) vehicle rolled off the assembly line at the company’s Ulsan manufacturing facility today, as Hyundai became the world’s first automaker to begin assembly-line production of zero-emissions, hydrogen-powered vehicles for fleet use. The ix35 Fuel Cell vehicle, based on Hyundai’s popular ix35, C-segment SUV, exited the assembly line at Hyundai Motor Company’s Plant No. 5 during a launch event attended by Hyundai top management and VIPs. The ix35 Fuel Cell unveiled at the ceremony will be one of 17 destined for fleet customers in the City of Copenhagen, Denmark, and Skåne, Sweden. Copenhagen, as part of its initiative to be carbon-free by 2025, will be supplied with 15 ix35 vehicles for fleet use, according to an agreement that was announced in September 2012. Two also will be supplied to Skåne, Sweden. “Assembly-line production of fuel cell vehicles marks a crucial milestone in the history of the automobile industry not just in Korea, but throughout the world,” says Mang Woo Park, mayor of Ulsan city. Hyundai plans to build 1,000 ix35 vehicles by 2015 for lease to public and private fleets, primarily in Europe, where the European Union has established a hydrogen road map and initiated construction of hydrogen fueling stations.
With imported petroleum dropping from 60 percent of total consumption to less than 40 percent in the past six years, in part due to the explosion of onshore oil exploration and development, the US has made progress toward its goal of reducing dependence on foreign oil. On March 5, energy leaders will come together with faculty of the University of Oklahoma Price College of Business Energy Institute for a national energy symposium with the objective of developing a long-term energy strategy for the country. Some of the nation’s leading energy executives, economists and national security leaders will share their diverse perspectives to identify priorities and challenges in shaping a cohesive energy strategy and enabling policy. The long-term energy strategy symposium organizers expect to develop will be designed to address the realities of energy resource options, take into account global resources, competition and US options, and provide a balanced view of resource reliability, economics and environmental impact. Panelists also will address the role of government in energy policy that they believe would enable successful implementation for a cohesive, long-term energy strategy. The keynote speaker is Adam Sieminski, administrator, US Energy Information Administration.
(Nature) Glass transition, in which viscosity of liquids increases dramatically upon decrease of temperature without any major change in structural properties, remains one of the most challenging problems in condensed matter physics despite tremendous research efforts in past decades… [T]he characterization of the similarity between spin and the structural glass transition remains an elusive subject. In this study, we introduced a model structural glass with built-in quenched disorder that alleviates this main difference between the spin and molecular glasses, thereby helping us compare these two systems: the possibility of producing a good thermalization at rather low temperatures is one of the advantages of this model.