Scientists have helped solve an 80-year-old puzzle about a widely used chemical process.
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A new technique simultaneously illuminates the location, orientation and rotation in 3D of individual gold nanorods. Gold nanorods have been used as orientation probes in optical imaging because of their shape-induced anisotropic optical properties and now we can do this even better. Gold nanorods have the benefits of being biocompatible and having optical properties that depend on their orientation. This new development provides full 360° rotational information about these nanorods without sacrificing spatial and time resolution.
Capitalizing on the concept that everything proceeds faster with a little cooperation, researchers showed how designing cooperation into solid catalysts leads to enormous benefits.Catalysts attached to a porous solid support are preferred industrially because they are easier to separate from liquid products and reuse. But, these bound catalysts typically do not perform as well and probing their interiors to figure out how to improve them has proved difficult until now. Using new solid-state nuclear magnetic resonance (SSNMR) methods (the equivalent of running an MRI on the catalyst) and
Scientists have discovered that the growth of iron on graphene — a one atom thick layer of carbon — occurs in an unusual way. For other metals the first atoms to arrive form small clusters on the graphene surface, and then the clusters migrate across the surface, seemingly at random. Whenever two clusters encounter each other, they merge to form a larger cluster, which moves a little slower. Growing these larger clusters is important for making electronic connections to graphene for microelectronic applications.
Significant LED performance improvements have been achieved by taking advantage of novel materials.An organic light emitting diode (OLED) requires at least one transparent electrode, which is most commonly indium tin oxide (ITO). While ITO is both transparent and a good electrical conductor, its light transmission differs from the other organic material layers used in the device, leading to internal reflections which reduce efficiency. Researchers replaced ITO with a special highly conductive polymer known as PEDOT:PSS.
A new theoretical advance enables us to understand how the magnetic properties of a class of magnets called antiferromagnets respond to a magnetic field. The theory describes the magnetic behaviors of both collinear antiferromagnets, in which adjacent magnetic moments point in opposite directions from atom-to-atom, and noncollinear antiferromagnets, where the magnetic moments rotate from one atom to the next. Advantages of this theory include that it is expressed in quantities that are easily measurable and is useful for polycrystalline samples.
The Helfand and Werthamer theory developed in 1960s predicts the magnetic field at which a superconductor turns into a normal metal if certain details of the electronic structure are known. When new superconductors are discovered, their upper critical field is usually analyzed using this theory, even though it has a well-known shortcoming — it assumes that the electronic properties of the superconductor are the same in all directions and lead to an isotropic upper critical field.
Magnetism behaves very strangely in compounds of lanthanum, strontium, cobalt and oxygen, and researchers have just attained new insight into the decades-old question of why. Pure LaCoO3 is a non-magnetic, narrow-gap semiconductor at low temperatures, but it acquires magnetic properties as the temperature is raised – in contrast with most materials, which tend to lose magnetism at higher temperatures. With strontium doping the magnetic properties become more prominent until, at 18% Sr, the compound becomes metallic and ferromagnetic, like iron.
Light, combined with a novel rhodium catalyst, enables greener production of chemical feedstocks from biorenewables. A key challenge in the utilization of biomass for fuels and fine chemical applications is the control of oxygen and nitrogen-containing functional groups.Unfortunately, current routes such as gasification also generate unwanted by-products such as carbon dioxide and carbonaceous material.
Minute chemical substitutions are used to induce superconductivity in many materials, but the precise role of these dopants in iron-pnictide superconductors is an ongoing debate. In semiconductors, doping allows charge carrier concentrations to be controlled enabling electronic devices to be created. However, dopants in iron-arsenide superconductors do not simply impact charge carrier concentrations.