Science

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Moth-Inspired Nanostructures Take the Color Out of Thin Films

Thin-film interference is a well-known effect, and it is commonly observed in the colored appearance of many natural phenomena. Caused by the interference of light reflections from the interfaces of thin material layers, such interference effects can lead to wavelength and angle-selective behavior in thin-film devices.

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The nanostructures limit the amount of light reflected at the thin film interface.

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Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem

In the wake of the sobering news that atmospheric carbon dioxide is now at its highest level in at least three million years, an important advance in the race to develop carbon-neutral renewable energy sources has been achieved.

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Schematic shows TiO2 nanowires (blue) grown on the upper half of a Si nanowire (gray) and the two absorbing different regions of the solar spectrum. Insets display photoexcited electron−hole pairs separated at the semiconductor-electrolyte interface to carry out water splitting with the help of co-catalysts (yellow and gray dots).

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Add boron for better batteries: graphene-boron mix shows promise for lithium-ion batteries

Frustration led to revelation when Rice University scientists determined how graphene might be made useful for high-capacity batteries.

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A theory developed at Rice University determined that a graphene/boron compound would excel as an ultrathin anode for lithium-ion batteries. The compound would store far more energy than graphite electrodes used in current batteries.

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Moth-Inspired Nanostructures Take the Color Out of Thin Films

Thin-film interference is a well-known effect, and it is commonly observed in the colored appearance of many natural phenomena. Caused by the interference of light reflections from the interfaces of thin material layers, such interference effects can lead to wavelength and angle-selective behavior in thin-film devices. In this work, we describe the use of interfacial nanostructures to eliminate interference effects in thin films. Using the same principle inspired by the moth-eye structures, this approach creates an effective medium where the index is gradually varying between the neighboring materials. We present the fabrication process for such nanostructures at a polymer-silicon interface, and experimentally demonstrate its effectiveness in suppressing thin-film interference. The principle demonstrated in this work can lead to enhanced efficiency and reduce wavelength/angle sensitivity in multilayer optoelectronic devices.

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The nanostructures limit the amount of light reflected at the thin film interface.

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Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem

Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem

47485.jpg
Schematic shows TiO2 nanowires (blue) grown on the upper half of a Si nanowire (gray) and the two absorbing different regions of the solar spectrum. Insets display photoexcited electron−hole pairs separated at the semiconductor-electrolyte interface to carry out water splitting with the help of co-catalysts (yellow and gray dots).

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Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard

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These false-color SEM images reveal microscopic flower structures created by manipulating a chemical gradient to control crystalline self-assembly.

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Mars Rover Opportunity Examines Clay Clues in Rock

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The pale rock in the upper center of this image, about the size of a human forearm, includes a target called "Esperance," which was inspected by NASA's Mars Exploration Rover Opportunity. Data from the rover's alpha particle X-ray spectrometer (APXS) indicate that Esperance's composition is higher in aluminum and silica, and lower in calcium and iron, than other rocks Opportunity has examined in more than nine years on Mars. Preliminary interpretation points to clay mineral content due to intensive alteration by water.

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Activity Continues On the Sun

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NASA's Solar Dynamics Observatory captured this image of the X1.2 class solar flare on May 14, 2013. The image show light with a wavelength of 304 angstroms.

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New Stanford Nanoscavengers Could Usher In Next Generation Water Purification

Among its many talents, silver is an antibiotic. Titanium dioxide is known to glom on to certain heavy metals and pollutants. Other materials do the same for salt. In recent years, environmental engineers have sought to disinfect, depollute, and desalinate contaminated water using nanoscale particles of these active materials. Engineers call them nanoscavengers. The hitch from a technical standpoint is that it is nearly impossible to reclaim the nanoscavengers once in the water.

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A dead E. coli bacterium collected in a filter after treatment with the Stanford nanoscavenger.

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Squishy hydrogels may be the ticket for studying biological effects of nanoparticles

A class of water-loving, jelly-like materials with uses ranges ranging from the mundane, such as superabsorbent diaper liners, to the sophisticated, such as soft contact lenses, could be tapped for a new line of serious work: testing the biological effects of nanoparticles now being eyed for a large variety of uses.

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After four days, quantum dots still shine (green) in cells embedded in a hydrogel scaffold.

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