Physics Today Daily Edition
BBC: Graphene, the single-atom-thick arrangement of carbon atoms with a wide range of curious properties, was first isolated at the University of Manchester in the UK in 2004. Now, researchers from the university have contributed to the design of the first commercial consumer product to use graphene: a light bulb with a graphene-coated filament. The increased conductivity of the graphene reduces the bulb's energy use by 10% and lengthens the bulb's lifetime. The bulbs are expected to be available for sale later this year for under £15 ($22), which is less expensive than current LED bulbs.
New York Times: Coal still supplies two-thirds of China's power generation, but with the nation's economy growing at the slowest rate in 25 years and a mandated shift to nuclear and renewable sources, coal imports and utilization have dropped significantly over the last year. In 2014 the use of fossil fuels to generate power was at a record low of 53.7%, down from 57.3% in 2013. That reduction led to a drop of 18 million tons or 1.3% in the amount of coal used and to a 11% reduction in coal imports by the world's largest coal consumer. The trend is expected to continue through 2015. As a result, the cost of coal from Australia, one of China's primary sources, fell 30% last year to under $60 per ton this month, the lowest since May 2007.
BBC: Observations of 72 galactic collisions have revealed to a higher level of detail than ever before that dark matter is unaffected by any force other than gravity. Richard Massey of Durham University in the UK and his colleagues used Hubble Space Telescope and Chandra X-ray Observatory to observe the collisions in both visible and x-ray light. The x-ray images revealed the movement of the clouds of plasma that reside inside and around galaxies whereas the visible images showed the movements of the stars. The combined images allowed the researchers to measure the gravitational lensing effect of the dark matter. The observations revealed that the dark matter exhibited no sign of non-gravitational interactions with itself or other matter to a much higher level of precision than previous observations.
Los Angeles Times: In the early 1980s the Voyager spacecraft measured the length of Saturn's day to be 10.6 hours based on the planet's magnetic field. But when Cassini reached the planet in 2004, it obtained a different result. Subsequent measurements revealed that the planet's magnetic field, unlike Earth's, is aligned with the axis of rotation; it cannot, therefore, be used for an accurate measurement. Other techniques that attempted to use the planet's wind patterns proved even less accurate. Ravit Helled of Tel Aviv University and his colleagues have now used Saturn's gravitational field to measure the length of the day, which they found to be 6 minutes shorter than the original Voyager measurement. The technique uses the periodic changes in pull that Cassini feels as Saturn rotates as well as measurements of the planet's oblateness. The researchers confirmed the accuracy of the technique by testing it against Jupiter, whose day has a well-known length.
Nature: The oxygen atom in a water molecule is tightly bound to the two hydrogen atoms, but it also experiences a slight connection with the hydrogen in neighboring molecules. Because of this, as water freezes, the molecules arrange themselves into three dimensional tetrahedral shapes. Now, Andre Geim of the University of Manchester, UK and his colleagues have discovered that water pressed between sheets of graphene freezes into an ice in which the molecules form two-dimensional layers of square shapes. The structure could be the 18th different type of water ice discovered. Geim's team calculated that the pressure exerted on the water by the graphene sheets exceeds 10 000 atm or 1 gigapascal.
Nature: On 24 March Department of Energy (DOE) secretary Ernest Moniz announced that the agency was looking for a variety of temporary localized sites for nuclear waste storage. The agency will also continue its search for a permanent, geologically stable location for long-term storage of nuclear weapons waste. Moniz says that the key to the localized sites is that the agency will be seeking consent-based locations instead of attempting to force storage sites into areas where the local population does not want them. The DOE's new plan, with President Barack Obama's approval, also frees commercial and military waste to be stored in separate locations. Thanks to the policy change, waste repositories will no longer have to be equipped to store waste that has different requirements and risks. The DOE's 2016 budget proposal includes funding for an experimental borehole for long-term storage. The agency also plans to begin evaluating potential storage sites for commercial waste, but construction of such facilities would require approval from Congress.
Science: The Large Hadron Collider (LHC) at CERN was planned to begin circulating beams of particles the entire way around the accelerator's 27-km circumference this week. However, an electrical short discovered over the weekend has delayed the full restart while the short is repaired. That task could take as little as a few days or as long as several weeks. Shorts are not uncommon as the LHC is slowly ramped up, but the time it takes to repair them can be significantly increased if supercooled electronics first have to be warmed up. The scientists working at the accelerator plan to use x-ray imaging to examine the area to determine if they can remove the metallic source of the short by melting it or blowing it away with helium.