Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 4 days 2 hours ago

Microfabrication technique doubles solar-cell efficiency

17 December 2014

MIT Technology Review: The technology behind manufacturing solar cells is similar to that behind making microprocessors. French company Soitec has exploited its expertise in microfabrication to develop a solar cell that adds four semiconductors in two layers. Each semiconductor absorbs energy from different parts of the light spectrum; together they convert sunlight to energy at a more efficient rate than one wide-spectrum semiconductor, which is more typical in other designs. Although the cell's solar efficiency is now at 46%, the process is currently expensive compared with the price of making competing products.

Satellite sees ground movement after quake

17 December 2014

BBC: Europe's Sentinel-1a satellite, which was launched earlier this year, has provided the first high-resolution images of ground movement after an earthquake. Back in August, California's Napa Valley suffered an earthquake. Because Sentinel-1a flies over and takes a snapshot of the surrounding area every 12 days, researchers have been able to track the earthquake's aftermath. The high-resolution images have captured the surface creeping forward at a rate of 5 cm per month. The data will allow researchers to see which parts of a fault line "stick" and potentially cause an earthquake and which parts flow over the surrounding rock.

US will stay in ITER

17 December 2014
Omnibus spending bill removes the threat of US withdrawal from project. The measure also boosts US domestic fusion program.

Raman spectroscopy finds rickets disease in Tudor sailors

16 December 2014
Daily Mail: Bones and artifacts from an almost 500-year-old shipwreck are now being analyzed using Raman spectroscopy and DNA analysis. When Henry VIII’s flagship Mary Rose sank in battle on 19 July 1545, more than 400 men, and one dog, died. The wreck settled into the muddy bottom on the floor of the Solent, the strait separating the Isle of Wight from mainland England. It lay there preserved until October 1982, when it was raised and an ambitious conservation effort begun. Over the next three decades, the ship’s hull underwent constant spraying with millions of liters of water and wax chemicals to preserve it. In addition, bones of the sailors who perished on board have been examined. One thing the researchers discovered was that many of the sailors appear to have suffered from metabolic bone disease, such as childhood rickets.

Modeling behavior of synthetic materials

16 December 2014

The Telegraph: Computationally modeling chemical processes from quantum mechanical principles has been a challenging task because of the large number of pieces and the large number of steps in interactions that need to be calculated. Now Peter Coveney, James Suter, and Derek Groen of University College London have developed an efficient way of modeling the behaviors of composites of clays and polymers from the quantum scale up. They were able to accurately model the characteristics of synthetic materials they'd created in the lab; they began the modeling with the behavior of the materials' electrons and then progressed to the atomic level and then to the molecular level. Their modeling system could be useful for predicting the behaviors of potential new materials, including new composites that contain molecules like graphene.

Nuclear sites get federal historical park status

16 December 2014

New York Times: On 12 December Congress approved the establishment of a new national historic park to preserve sites associated with the World War II secret Manhattan Project, which built the world's first atomic weapons. The park will encompass lands and buildings in New Mexico, Tennessee, and Washington, including the home of J. Robert Oppenheimer, the scientific director of the project, and buildings where much of the research and construction of the Trinity device and the Fat Man and Little Boy bombs took place. The effort to preserve the various sites was led by the Atomic Heritage Foundation. President Obama is expected to sign the legislation into law this week.

Densest Amazon store of carbon is in the peat

16 December 2014

BBC: A 120 000 km2 area that accounts for just 3% of the Peruvian Amazon basin contains almost 50% of the basin's carbon stock. Freddie Draper of the University of Leeds, Katy Roucoux of the University of St Andrews, and their colleagues combined two years of measurements on peat depth, density, and carbon percentage with satellite imagery to reach that conclusion. The imagery revealed that the peatlands were more widespread than expected. The direct measurements of ground carbon revealed that the peat accounted for 90% of the area's carbon. Draper and Roucoux say that the peatlands are still mostly intact but that preservation efforts should be started now to prevent any damage to the ecosystems.

Large number of methane deposits releasing gas along US East Coast

15 December 2014

Earth Magazine: Sea-floor methane deposits are commonly found leaking gas in tectonically active areas or in areas rich in petroleum. They are considered to be a potentially significant contributor of greenhouse gases. Now Adam Skarke of Mississippi State University and his colleagues have found 570 methane seeps along the tectonically quiet and oil-poor East Coast of the US. Skarke's team used multibeam sonar, commonly used for producing 3D maps of the sea floor, to find the seeps. Previous scans of the region did not have a resolution capable of detecting the small bubbles up to 1.6 km below sea level. Despite the large number of seeps found, the amount of gas being released by them is quite small. However, the discovery suggests that the search for seeps should be expanded to areas that were not previously considered likely sites.

Fuel cell provides alternative for carbon capture

15 December 2014

New York Times: FuelCell Energy has received a $2.5 million grant from the US Department of Energy for an experimental fuel cell it developed that can be used to capture carbon dioxide emissions from coal power plants. The fuel cell combines natural gas and air without combustion to produce CO2 and steam and to generate electricity. Then the mixture is easily cooled to −40 °C so that the CO2 can condense and separate out. When the fuel cell is fed waste air containing 13% CO2, about the level from a coal power plant, the additional CO2 is captured in the condenser. As an additional bonus, the fuel cell generates excess electricity that can be used by the power plant. 

Star birth appears to drive galactic gas cloud formation

15 December 2014

Ars Technica: The visible matter that makes up galaxies is primarily in the form of stars, but many galaxies have large clouds of molecular gas around them. How that gas got there is unclear because most theories about galaxy formation predict that the gas should have stayed in the galaxies and coalesced into stars. Now observations of a distant galaxy may provide some clues into the process. The observed galaxy, J0905, is extremely compact, with half of its star formation coming from a region just 100 parsecs in diameter. It is spewing gas outwards into space at a flow rate of 2 500 km/s, 10 times more than the average for other galaxies. Curiously, the mass of the gas lost each year is roughly equal to the mass of new stars that J0905 produces each year. Because of the galaxy's compactness, the combined radiation from the new stars appears to be the source of the "wind" driving the gas out of the galaxy.

Cytoskeleton rheology

15 December 2014
Mechanical properties of single cells can be difficult and time-consuming to unravel. A new instrument allows such properties to be deduced from experiments on a large group.

Physicist’s <em>Wall Street Journal</em> op-ed engages movies

15 December 2014
“Perils of romanticizing physics: Bravo for Interstellar and The Theory of Everything, but let’s not get carried away.”

Cutting carbon emissions could have more immediate benefits, says study

12 December 2014
Ars Technica: Previous studies have proposed that because of the heat capacity of Earth's oceans, the benefits of cutting fossil fuel emissions could take almost a half century to be realized. However, new research shows that the median time between a given carbon dioxide emission and maximum warming may be much less than that. The researchers gauged Earth’s temperature response by simulating the effect of a pulse of 100 gigatons of CO2 that abruptly ceases. The researchers focused on three variables: climate sensitivity, the ocean’s thermal inertia, and carbon cycle activity. For 90% of their simulations, surface temperature stopped rising in as little as 10 years. The point of the study was to demonstrate the early benefits of cutting greenhouse gas emissions.

Pages