Wednesday 6 August 2014

First Ab Initio Method for Characterizing Hot Carriers Could Hold the Key to Future Solar Cell Efficiencies

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One of the major road blocks to the design and development of new, more efficient solar cells may have been cleared. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) have developed the first ab initio method – meaning a theoretical model free of adjustable or empirical parameters – for characterizing the properties of “hot carriers” in semiconductors. Hot carriers are electrical charge carriers – electrons and holes – with significantly higher energy than charge carriers at thermal equilibrium. “Hot carrier thermalization is a major source of efficiency loss in solar cells, but because of the sub-picosecond time scale and complex physics involved, characterization of hot carriers has long been a challenge even for the simplest materials,” says Steven Louie, a theoretical physicist and senior faculty scientist with Berkeley Lab’s Materials Sciences Division (MSD). “Our work is the first ab initio calculation of the key quantities of interest for hot carriers – lifetime, which tells us how long it takes for hot carriers to lose energy, and the mean free path, which tells us how far the hot carriers can travel before losing their energy.” All previous theoretical methods for computing these values required empirical parameters extracted from transport or optical measurements of high

The post First Ab Initio Method for Characterizing Hot Carriers Could Hold the Key to Future Solar Cell Efficiencies has been published on Technology Org.

 
#materials 
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Study explains how Maxwell's demon uses mutual information to extract work

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(Phys.org) —Maxwell's demon, the hypothetical doorman that controls how particles travel between two chambers in an attempt to decrease entropy, is at its heart a feedback-controlled system. The demon makes measurements on the microscopic state of the system, stores the measurement outcomes in its memory, and uses the information as a kind of "thermodynamic fuel" to extract work from the system.



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NASA's Hubble Finds Supernova Star System Linked to Potential 'Zombie Star'



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Supernovae are the most powerful stellar explosions in the universe. Some of them are produced by the detonation of a white dwarf, the stripped-down core of an ordinary star at the end of its life. But 12 years ago, astronomers began noticing weak stellar blasts, a kind of mini-supernova. When one such explosion occurred in the galaxy NGC 1309, astronomers looking through Hubble archival images found for the first time the star system that produced the supernova blast of a white dwarf.




via HubbleSite NewsCenter -- Latest News Releases

http://hubblesite.org/newscenter/archive/releases/2014/32/

2014 ORBITAL CALENDAR: Solar System Poster

Here's a great poster featuring a beautiful image from deep space


tagged with: astronomy poster, circular calendar, phases of the moon, spacetime, calendar cycles, timespace

Astronomy Science Poster EARTH-MOON w/ SOLAR SYSTEM ~ Your Year In Space! ~ Astronomically-correct TimeSpace, MILKY WAY Galaxy in background Perfect for S.T.E.M Education: TEACH astronomy in a flash... . ...from Earth to Moon to Sun, celestial math. Use Dry Erase markers to add your data, meteor showers, study cycles, National Calendar Awards for: Most Original, Most Educational Best Graphic Design

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Rosetta: 100 kilometres to 'touchdown'

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The Rosetta spacecraft is approaching just 100 kilometres from its target comet, "Chury", today. After a ten-year journey, the Bernese instrument, ROSINA, will soon "smell" the first molecules of the comet's gas tail.

via Science Daily

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Triangulum galaxy snapped by VST

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The VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile has captured a beautifully detailed image of the galaxy Messier 33. This nearby spiral, the second closest large galaxy to our own galaxy, the Milky Way, is packed with bright star clusters, and clouds of gas and dust. The new picture is amongst the most detailed wide-field views of this object ever taken and shows the many glowing red gas clouds in the spiral arms with particular clarity.

via Science Daily

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Rosetta spacecraft arrives at comet destination

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After a decade-long journey chasing its target, ESA's Rosetta has today become the first spacecraft to rendezvous with a comet, opening a new chapter in Solar System exploration. Comet 67P/Churyumov-Gerasimenko and Rosetta now lie 405 million kilometres from Earth, about half way between the orbits of Jupiter and Mars, rushing towards the inner Solar System at nearly 55,000 kilometres per hour.

via Science Daily

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How Rosetta arrives at a comet

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After travelling nearly 6.4 billion kilometres through the Solar System, ESA's Rosetta is closing in on its target. But how does a spacecraft actually arrive at a comet?

via Science Daily

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Rosetta takes comet’s temperature

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ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

via Science Daily

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Living in the shadow of Ebola

Science Focus

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Three rules on how to survive the deadly virus 
#science 
 » see original post http://www.bbc.co.uk/news/magazine-28583051#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
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Storm Chasing on Saturn

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The sun is slowly rising over Saturn’s North Pole, exposing an immense six-sided hurricane. The storm, big enough to swallow four Earths, was first spotted by the Voyager missions in the early 1980s.















via New York Times

Out There: Storm Chasing on Saturn

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In its latest spins around the ringed planet, NASA’s Cassini craft has focused on a lesser known but hardly less mysterious feature: a hexagon vortex.















via New York Times

The Active Cigar Galaxy - Messier 82 Sticker

Here's a great sheet of stickers featuring a beautiful image from deep space


tagged with: stars, galaxies, outer space, agmet, galaxies and stars, hubble, chandra, messier 82, cigar galaxy, active galaxies, peel off

Galaxies, Stars and Nebulae series

Composite of images of the active galaxy Messier 82 from the three Great Observatories: Hubble Space Telescope, Chandra X-Ray Observatory, and Spitzer Space Telescope. X-ray data recorded by Chandra appears here in blue, infrared light recorded by Spitzer appears in red. Hubble's observation of hydrogen emission appears in orange. Hubble's bluest observation appears in yellow-green.

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All items in the Galaxies, Stars and Nebulae series

Image code: agmet

Image credit: Hubble Space Telescope, Chandra X-Ray Observatory, Spitzer Space Telescope

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Saturn's Swirling Cloudscape

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Acquiring its first sunlit views of far northern Saturn in late 2012, the Cassini spacecraft's wide-angle camera recorded this stunning, false-color image of the ringed planet's north pole. The composite of near-infrared image data results in red hues for low clouds and green for high ones, giving the Saturnian cloudscape a vivid appearance. Enormous by terrestrial standards, Saturn's north polar hurricane-like storm is deep, red, and about 2,000 kilometers wide. Clouds at its outer edge travel at over 500 kilometers per hour. Other atmospheric vortices also swirl inside the large, yellowish green, six-sided jet stream known as the hexagon. Beyond the cloud tops at the upper right, arcs of the planet's eye-catching rings appear bright blue.

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Postcards from Rosetta

Graphene 'droplets' open up possibilities in drug delivery, disease detection

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A chance discovery about the 'wonder material' graphene takes it a step closer to being used in medicine and human health. Researchers in Australia have discovered that graphene oxide sheets can change structure to become liquid crystal droplets spontaneously and without any specialist equipment. With graphene droplets now easy to produce, researchers say this opens up possibilities for its use in drug delivery and disease detection.

via Science Daily

Hubble eXtreme Deep Field (XDF) Cases For iPad

Here's a great iPad case from Zazzle featuring a Hubble-related design. Maybe you'd like to see your name on it? Click to personalize and see what it's like!


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European Spacecraft Pulls Alongside Comet

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After 10 years and a journey of four billion miles, the Rosetta probe arrived at its destination for the first extended, close examination of a comet.















via New York Times

Planting imperfections at specific spots within diamond lattice could advance quantum computing

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By carefully controlling the position of an atomic-scale diamond defect within a volume smaller than what some viruses would fill, researchers have cleared a path toward better quantum computers and nanoscale sensors. They describe their technique in a paper published in the journal Applied Physics Letters, from AIP Publishing.



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“Hello, comet!”

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After a decade-long journey chasing its target, Rosetta has today become the first spacecraft to rendezvous with a comet

via ESA Space Science

http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_arrives_at_comet_destination

ALMA pinpoints Pluto to help guide NASA’s New Horizons spacecraft

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Astronomers are making high-precision measurements of Pluto's location and orbit around the Sun to help NASA’s New Horizons spacecraft accurately home in on its target when it nears Pluto and its five known moons in July 2015.

via Science Daily

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Space, stars, galaxies and nebulas posters

Here's a great poster featuring a beautiful image from deep space


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This is a unique fantasy space composition made from a collage of real space images.

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Enhanced Hubble Image of Comet iPad Folio Cases

Here's a great iPad case from Zazzle featuring a Hubble-related design. Maybe you'd like to see your name on it? Click to personalize and see what it's like!


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