Earth's most severe mass extinction - an event 250 million years ago that wiped out 90 percent of all marine species and 70 percent of land vertebrates - was triggered by a collision with a comet or asteroid, according to a team led by The University of Washington, Seattle, USA. Evidence is based upon elegant findings involving carbon molecules called buckminsterfullerenes (C60, Buckyballs) with the gases helium and argon trapped inside their cage structures.
The scientists do not know the site of the impact 250 million years ago, when all Earth's land formed a supercontinent called Pangea. However, the space body left a calling card - a much higher level of complex carbon molecules called buckminsterfullerenes, or Buckyballs, with the noble (or chemically nonreactive) gases helium and argon trapped inside their cage structures. Fullerenes, which contain 60 or more carbon atoms and have a structure resembling a soccer ball or a geodesic dome, are named for Buckminster Fuller, who invented the geodesic dome.
The researchers know these particular Buckyballs are extraterrestrial because the noble gases trapped inside have an unusual ratio of isotopes. For instance, terrestrial helium is mostly helium-4 and contains only a small amount of helium-3, while extraterrestrial helium - the kind found in these fullerenes - is mostly helium-3.
"These things form in carbon stars. That's what's exciting about finding fullerenes as a tracer," according to Luann Becker, one of scientific team involved. The extreme temperatures and gas pressures in carbon stars are perhaps the only way extraterrestrial noble gases could be forced inside a fullerene, she said. These gas-laden fullerenes were formed outside the Solar System, and their concentration at the Permian-Triassic boundary means they were delivered by a comet or asteroid.
Nobel laureate Richard Smalley, the Rice University professor who helped discover buckyballs (buckminsterfullerene, C60, the football (soccer) ball shaped form of carbon, died at the age of 62. Richard Smalley shared the 1996 Nobel Prize in chemistry with Sir Harold Kroto (Sussex) and Robert Curl (also Rice) for the identification of the new form of carbon known as buckminsterfullerene because of its similarity to Buckminster Fuller's geodesic domes. The Richard E. Smalley Institute for Nanoscale Science and Technology continues to champion the efforts of Smalley through research, educational and community programs, corporate partnerships, and government relations.
A NASA press release indicates that NASA's Spirit, the first of two Mars Exploration Rovers on the surface within Mars' Gusev crater, has identified carbonate minerals "in the rover's first survey of the site with its infrared sensing instrument, called the miniature thermal emission spectrometer or Mini-TES. Carbonates form in the presence of water, but it's too early to tell whether the amounts detected come from interaction with water vapor in Mars' atmosphere or are evidence of a watery local environment in the past, scientists emphasized."
"We came looking for carbonates. We have them. We're going to chase them," said Dr. Phil Christensen of Arizona State University, Tempe, leader of the Mini-TES team. Previous infrared readings from Mars orbit have revealed a low concentration of carbonates distributed globally. Christensen has interpreted that as the result of dust interaction with atmospheric water. First indications are that the carbonate concentration near Spirit may be higher than the Mars global average.
After the rover drives off its lander platform, infrared measurements it takes as it explores the area may allow scientists to judge whether the water indicated by the nearby carbonates was in the air or in a suspected ancient lake. http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040109a/graph-carb...
This graph, consisting of data from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signatures of carbonates - organic molecules common to Earth that form only in water. The detection of trace amounts of carbonates on Mars may be due to an interaction between the water vapor in the atmosphere and minerals on the surface.
Image credit: NASA/JPL/Arizona State University
The U.S. Department of Energy's Brookhaven National Laboratory reports that scientists at the US Brookhaven National Laboratory and the IBM T.J. Watson Research Center caused an individual carbon nanotube to emit light for the first time. This may have significance for many of the proposed applications for carbon nanotubes including in electronics and photonics.
The light emission is the result of a process called "electron-hole recombination." By running an electric current through a carbon nanotube - a long, hollow cylindrical molecule that is only one and a half nanometers (a billionth of a meter) in diameter - negatively charged electrons in the nanotube molecule combine with positively charged "holes," which are locations in the molecule where electrons are missing. When an electron fills a hole, it emits a photon - a tiny burst of light.
"We produced infrared light by applying voltages to a specific type of nanotube such that many electrons and holes end up in the nanotube, where they combine. This makes the nanotube the world's smallest electrically-controllable light emitter," said James Misewich, a materials scientist at Brookhaven. "It's an exciting result, and my colleagues and I plan to continue studying the effect to determine the mechanisms behind it. For example, we hope to understand how to make the nanotubes emit other types of light, such as visible light, and how to increase the efficiency of the emission." Carbon nanotubes do not yet have any mainstream practical applications, but researchers are investigating ways to use them in flat-panel displays, such as televisions and computer monitors, or as reinforcements in building materials, due to their exceptional mechanical strength. Misewich also suggested that, if additional research leads to an increased efficiency of nanotube light emission, the nanotubes could possibly be used in lighting applications.
Workers in Russia and Los Alamos, USA report in Nature1 superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2500-2800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond (carbon) is a bulk, type-II superconductor below the superconducting transition temperature Tc 4 K.
Boron has one less electron than carbon and, because of its small atomic radius, is relatively easily incorporated into diamond. The boron acts as a charge acceptor and the resulting diamond is effectively hole-doped.
Abstract: Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500–2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature Tc about 4 K; superconductivity survives in a magnetic field up to Hc2(0) 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.Superconductivity in diamond, , Nature, 4/2004, Volume 428, Issue 6982, p.542 - 545, (2004)
The observation that soot makes global warming "worse" is well covered today. The BBC covers this - largely because it appears that soot is more important for global warming than realised earlier. Dr James Hansen and Larissa Nazarenko, (Goddard Institute for Space Studies, NASA, and Columbia University Earth Institute) suggest that trying to reduce the amount of soot produced would be easier than cutting carbon dioxide and other greenhouse gas emissions. Concentrations of soot are often high over China and India, where coal and organic fuels are used domestically, and over Europe and North America, where the main source is diesel oil.1
Abstract: plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The “efficacy” of this forcing is ∼2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future.Soot climate forcing via snow and ice albedos, , Proceedings of the National Academy of Sciences, 01/2004, Volume 101, Issue 2, p.423 - 428, (2004)
Nature reports that a new form of carbon was created when physicists at the Australian National University in bombarded a carbon target with a laser. As the carbon reached temperatures of around 10000 °C, it formed an intersecting web of carbon tubes called a 'nanofoam'. This is said to be a fifth form of carbon known after graphite, diamond, buckminsterfullerenes (buckyballs), and nanotubes. The foam is attracted to magnets. This may lead to new uses.1