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Geometry Matters

Researchers have discovered how the geometry of gold nanoparticles affects their images.  Gold nanoparticles can be imaged optically and their movements can be seen using a technique known as differential interference contrast (DIC) microscopy. How gold nanoparticles appear in these images depends upon their environment.  This can be used to learn about time-dependent nanoscale processes.

Watching the Nanoparticles Go Round and Round

Until now, watching the detailed spinning motion of nano-objects within living cells has been impossible.  Combining an existing technique, known as Differential Interference Contrast (DIC) Microscopy, with nanotechnology, researchers can now see how nanoparticles spin when they move across the interiors of living cells. Nano-sized rods made of gold are non-toxic to living cells and they scatter light differently depending on their orientation.

Road Blocks Yield Key Information about a Catalyst

Researchers systematically blocked key chemical reaction pathways to get unambiguous information about how carbon-nitrogen bonds are formed in a catalytic reaction known as hydroamination. Understanding a multi-step catalytic mechanism is like a solving a puzzle where you can’t see the pieces.  However, you can add your own “pieces” with known shapes to figure out what other pieces of the puzzle then will (or will not) fit.

Site Swap

Researchers have found evidence of atomic-scale defect formation during crystal growth from the supercooled liquid. Researchers have long speculated that defects incorporate during growth, but until now had no evidence because they heal before they can be observed. Using high energy, high resolution in situ X-ray diffraction at the U.S. Department of Energy’s Advanced Photon Source, researchers overcame accuracy and data collection speed issues to make this discovery. The researchers found evidence of defects that involve swapping of the locations of the elements in Zr2Cu.

Just a Little Spice Adds A Lot to the Mix

Scientists have discovered a way to improve the energy conversion efficiency of a key green material by 25%. Thermoelectric materials can convert waste heat into electricity, but the low efficiency of existing thermoelectric materials limits their widespread use.  Researchers found that by adding a little bit (just 1%) of the rare earths cerium or ytterbium to material made from silver, antimony, germanium and tellerium can make a huge difference.

Unconventional Field Expulsion

Researchers have found that two iron arsenide superconductors exhibit novel behavior. When a material is cooled below its superconducting transition temperature in an applied magnetic field, it expels some portion of that field. Exactly how this Meissner effect occurs depends on the physical properties of the sample, the type of superconductivity, and the experimental conditions. However, for all superconductors field expulsion is determined by the strength of the Meissner currents, which peak at some critical field value.

Strength without Compromise

Scientists have discovered a way to make strong materials that are also ductile. One of life’s classic problems is that whenever a metal or alloy is altered to make it stronger, it loses its ability to deform – it becomes brittle, so its eventual failure is both unheralded and catastrophic. Nanostructured materials have shown great improvements in strength over their conventional counterparts, but until now, they have also typically been more brittle.

Primal Magnetism

Quantum critical transitions take place at absolute zero and their occurrence can provide fundamental information about the onset of magnetism.  Studying quantum criticality is challenging, however, because we cannot make measurements at absolute zero, and we must rely on less distinct changes in the state of a solid, that occur at slightly higher temperatures.

Strong Interactions Need Not Apply

A new kind of magnetic order has been observed in barium-cobalt iron arsenide high-temperature superconductors by researchers with expertise in growing large single crystals, conducting x-ray and neutron measurements, and calculating electronic structures. Traditional antiferromagnetic order observed, for example, in the copper oxide high-temperature superconductors is driven by strong electron-electron interactions that can result in insulating behavior.


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