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Rounding Corners to Make Superconductors Work Better

Making superconducting nanocircuits with rounded internal corners will significantly improve performance.Scientists showed this by calculating how circuit geometry impacts current flow. The key is how geometry affects “current crowding”. Crowding can happen when electrical current travels around a sharp corner or hairpin turn much like cars racing on a tight track. The current (like cars) tends to concentrate near the inner edges of sharp turns.

Expulsion Leads to a New Catalyst

Locating a catalyst and reactants in confined spaces makes catalytic reactions go faster in the desired direction. Of course, the reaction products have to be removed from the confined spaces and researchers have developed a new approach to expelling aqueous reaction products. This works for confinement in nanometer-sized pores in silica particles. By lining the insides of the pores with both catalysts and a fluorinated chemical, like that found in Teflon®, reactions with water as a byproduct proceed much faster. This works because certain chemicals just don’t like each other.

Peculiar Magnetic Microstructure Pilots Badwater Bacteria

A new group of bacteria has been discovered in Death Valley’s Badwater Basin that makes nanoparticles of both magnetite (Fe3O4) and greigite (Fe3S4). Magnetotactic bacteria use these tiny magnets as part of their navigation system to align themselves along the Earth’s magnetic field. Typical magnetotactic bacteria do not make both magnetite and greigite and the discovery dispels the notion that greigite-producing bacteria live only in marine environments.

Untangling what Controls Superconductivity

Substituting ruthenium for iron in iron-based superconductors tunes their properties in a very unusual way. The substitution of one element for another normally changes the crystal’s electronic structure and induces superconductivity by adding charge carriers and/or altering the size of the crystal lattice. High resolution angle-resolved photoemission experiments showed neither mechanism is responsible in the case of barium–iron–ruthenium–arsenide, Ba(Fe1-xRux)2As2.

Ultrafast Moves — Caterpillar Style

A layer of lead on clean silicon moves in a surprising way — in waves like a caterpillar. This explains the unexpected ultrafast mass transport observed even at low temperatures for this system. Although solid these single layers of atoms move as fast as molten lead. Computer simulations show that the lead layer forms waves that require almost no energy to keep moving thus explaining the quickness of mass transport. Other metals on surfaces typically move much slower by one atom at a time hopping along the surface.

A Liquid with a Nanocrystalline Cover

Using the surface sensitive synchrotron X-ray capabilities at the U.S. Department of Energy’s Advanced Photo Source, researchers were able to figure out that the structure of the vapor/liquid interface of an ionic liquid is actually made up of tiny crystals even 100 °F above the liquid’s melting point.Ionic liquids consist of positive and negative ions.

Superconducting — Less the Magnetic Complications

A new iron-based superconductor, calcium-iron-platinum-arsenic, is magnetic but not superconducting at the lowest platinum concentrations and superconducting but not magnetic at the higher platinum levels; most of the other iron-based superconductors are both.This clear separation of magnetism and superconductivity in calcium-iron-platinum-arsenic lets scientists figure out what properties depend on superconductivity alone.

New Material Bridges the Gap between Superconductor Classes

A new material has been made to behave in two distinct ways, helping to break down a significant barrier for understanding the mechanisms of high temperature superconductivity. Known high temperature superconductors fall into two different classes — layered cuprates and iron arsenides. The undoped, parent compounds of the cuprates are insulating, while the parent compounds of iron arsenide superconductors are metallic.

Plant Cell Walls Demystified

Pectins have a previously unsuspected role in holding plant cells together, according to recent research.  Cell walls are made up of three major classes of polysaccharides:  cellulose, hemicellulose and pectins. The molecular interactions of these polysaccharides walls were studied for the first time within intact plant cells using multidimensional solid state NMR, a technique related to magnetic resonance imaging (MRI).

Remodeling Cellulose

The genetic modification of the plant cellulose structure has been demonstrated for the first time.This could be transformative for a bio-based economy.  Cellulose is difficult to break down to form the sugars needed to produce biofuels.

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