New Scientist: Amit Naskar and coworkers at Oak Ridge National Laboratory in Tennessee have found a way to convert the polyethylene in used plastic bags and other plastic waste into carbon fibers that can be fine-tuned for specific applications. Published in the journal Advanced Materials, their method involves mixing the polyethylene with polyactic acid, a compound derived from cornstarch or sugar cane. Then they heat the mixture and spin it into bundles of fibers 0.5–20 μm thick. Each fiber bundle is dipped into an acid-containing chemical bath, where it reacts to form a single black fiber that can’t melt even at very high temperatures. The heat, however, causes chemical components of the fibers to turn to a gaseous state, leaving behind a fiber composed mostly of carbon. By varying the process, the researchers can make fibers with different cross sections and porosities, which can be used for a variety of applications, such as filters for water desalination or lightweight composite materials for cars.
BBC: Cinthya Herrera, a doctoral student from Chile, is lead author on the first science paper to be based on observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) telescope. Intheir paper published last month in the journal Astronomy and Astrophysics, Herrera and coworkers discuss their investigation into star-forming clusters that result from the merger of a pair of spiral galaxies known as the Antennae Galaxies, which lie about 70 million light-years away. The 27-year-old student, who is currently at the Institute of Space Astrophysics in Paris, eventually intends to return to Chile, where the telescope is based. Although not yet finished, ALMA—supported by an international partnership among Chile and countries in North America, Europe, and East Asia—currently has 22 antennas in place, with a total of 66 planned for the next few years. Once ALMA is completely up and running, astronomers expect to be able to see very distant objects in the early universe, including some of the first structures to form more than 13 billion years ago, writes Jonathan Amos for the BBC.
BBC: A colossal picture of the Milky Way galaxy, 10 years in the making, has been created from thousands of individual images captured by two ground-based telescopes developed by the UK. “There are about one billion stars in there—this is more than has been in any other image produced by surveys,” said Nick Cross from the University of Edinburgh. Because of the vastness of the image, Cross and colleagues have produced an online interactive tool that allows the user to zoom in to particular areas. The two telescopes—the United Kingdom Infrared Telescope in Hawaii and the Visible and Infrared Survey Telescope for Astronomy in Chile—view the sky at IR wavelengths, which are much longer than those of visible light. As a result, light that passes through dusty regions of space can reach the telescopes without being scattered out of the line of sight. Astronomers will use data from the project to make new discoveries about the universe, writes Jonathan Amos for the BBC.
New York Times: This week the Planet Under Pressure conference in London brought together nearly 3000 people to discuss humanity’s impact on Earth. “Without urgent action, we could face threats to water, food, biodiversity and other critical resources,” wrote conference cochairs Lidia Brito and Mark Stafford Smith in a formal declaration issued at the end of the conference today. Among the suggestions are the need for a new United Nations Sustainable Development Council with its own secretariat and the need to replace the current measure of national well-being, gross domestic product, with a measure that better captures the impact of human economic activity. Besides discussing the prospects for better management of Earth and its resources, the conference was also called to build momentum for the upcoming United Nations Conference on Sustainable Development, Rio+20, to be held 20–22 June in Rio de Janeiro.
Arstechnica: Russian scientists have found that as many as 5000 low-energy neutrons per cubic meter are produced every second by lightning strikes. The results of their research were published last week in Physical Review Letters. Based on research begun in 1985, the new experiment used three detectors sensitive to low-energy neutrons—one aboveground, one partially shielded in a building, and one underground. The electrical activity of incoming storms was monitored using numerous instruments. Because cosmic rays also generate neutrons, the multiple detectors were needed to determine the neutrons’ origin: Neutrons from cosmic rays, created when muons collide in the detectors, have higher energy than neutrons from lightning, which lose energy by colliding with molecules in the air before they reach the detectors. The finding adds to the growing body of evidence that there is a lot more going on during thunderstorms than previously thought.
Los Angeles Times: On Tuesday the Obama administration released its long-awaited proposal to limit greenhouse gas emissions from power plants, which are the biggest single source of such emissions in the US. Under the new rule, the Environmental Protection Agency would bar new plants from emitting more than 1000 pounds of carbon dioxide per megawatt hour of electricity generated. It would effectively prevent construction of new coal-fired plants, which emit about 1600–1900 pounds per megawatt hour, in favor of those powered by natural gas. Strong opposition is expected from the coal industry, although the rule will not affect coal-fired plants already operating.
Space.com: A monolith located in Manchester, UK, is thought to have been erected by Neolithic people around 2000 BC as an astronomical tool to mark the changing seasons, writes Clara Moskowitz for Space.com. When Daniel Brown of Nottingham Trent University and colleagues recently surveyed the site, they discovered a high density of packing stones on one side, which indicates that the triangular-shaped stone was intentionally oriented to face a particular direction. The researchers used three-dimensional computer modeling to analyze how the stone would have been illuminated throughout the different seasons four millennia ago, given that the tilt of Earth’s axis has changed over time. Their model showed that the slanted side of the stone would have been brightly lit at midsummer and in shadow during the winter. According to Brown, “The stone would have been an ideal marker for a social arena for seasonal gatherings. It’s not a sundial in the sense that people would have used it to determine an exact time. We think that it was set in position to give a symbolic meaning to its location, a bit like the way that some religious buildings are aligned in a specific direction for symbolic reasons.” Although the use of shadow casting in monuments was rare during that period of time in England, examples have also been found in Ireland and Scotland.
BBC: To improve the quality of the Nestlé company’s ice cream, its food scientists teamed up with avalanche experts at the Institute for Snow and Avalanche Research in Switzerland to study ice crystal formation. Because the temperature does not remain constant in home freezers, ice cream continuously melts and then refreezes, which causes ice crystals to form, merge, and grow. The crystals affect the ice cream’s structure and, hence, its taste. As discussed in a paper published in the journal Soft Matter, x-ray tomography was used to create time-lapse studies of the evolution of ice cream’s microstructure. According to the researchers, their study of the life cycle of ice crystals in ice cream not only will help make a tastier dessert but also could provide “new insights into the coarsening mechanisms of multiphase materials and could contribute to a better understanding of complex materials.”
Nature: Mexico City, which was devastated in 1985 by a magnitude-8 earthquake that killed 9500 people, has since become a model for earthquake protection in the developing world. In the wake of the quake, the country changed its building regulations and pushed for better design and materials. The design had to take into account the city’s unique location—it was built over a lake that was gradually filled in by the Aztecs and, later, the Spanish. In an earthquake, the loose landfill tends to vibrate at just the right speed to enhance the shaking, and thus amplifies the quake long after the quake itself has dissipated. Last Tuesday, the renovations were put to the test when a 7.4-magnitude earthquake struck. This time around, there was little damage and no deaths. Although the quake was only a third as strong as the one in 1985, it should generate massive amounts of valuable data. “Mexico City in 1985 was a wake-up call for the engineering profession,” says Sergio Alcocer, a professor of engineering and secretary general of the National Autonomous University of Mexico in Mexico City. “Engineering has improved.”
Science: The leading theory for the Moon’s formation is that Earth and a Mars-sized planet collided some 4.5 billion years ago and produced a disk of magma that orbited Earth and over time coalesced to form the Moon. If so, say researchers, the Moon’s chemical composition should reflect that of both Earth and the other planet. However, studies of lunar rocks collected by the Apollo missions in the 1970s have cast doubt on that theory. Previous research established that the Moon’s oxygen isotope composition is indistinguishable from that of Earth. Now, according to a study published yesterday in Nature Geoscience by Junjun Zhang of the University of Chicago and colleagues, another isotope ratio, that of titanium-50 to titanium-47, has been shown to be similar on both Earth and the Moon. Although the oxygen finding can be explained because oxygen vaporizes easily and could have been exchanged between Earth and the newly forming Moon, titanium does not vaporize as easily. Despite the new evidence, Zhang does not completely rule out the earlier theory: “Our study cannot provide a definite answer to the origin of the Moon yet. The message we hope to convey is that isotopic homogeneity between the Earth and Moon is a fundamental new constraint on the evolution of the Earth–Moon system.”