Chemistry news, articles, and more

Sweet meteorites

A NASA scientist has discovered sugar and several related organic compounds in two meteorites -- providing the first evidence that another fundamental building block of life on Earth might have come from outer space.

Dr. George Cooper and coworkers from the NASA Ames Research Center found the sugary compounds in two carbon-rich (or carbonaceous) meteorites. Previously, researchers had found inside meteorites other organic, carbon-based compounds that play major roles in life on Earth, such as amino acids and carboxylic acids, but no sugars.

These discoveries add an important new piece to the puzzle of the origins of life on Earth, and supports the notion that seeds of life might be spread far and wide around the cosmos.1

"Finding these compounds greatly adds to our understanding of what organic materials could have been present on Earth before life began," Cooper said. "Sugar chemistry appears to be involved in life as far back as our records go." Recent research using ratios of carbon isotopes have pushed the origin of life on Earth to as far back as 3.8 billion years, he said. (An isotope is one of two or more atoms whose nuclei have the same number of protons but different numbers of neutrons.)

"This discovery shows that it's highly likely organic synthesis critical to life has gone on throughout the universe," said Kenneth A. Souza, acting director of astrobiology and space research at Ames. "Then, on Earth, since the other critical elements were in place, life could blossom."

Screensaver lifesaver

Anyone, anywhere with access to a personal computer, could help find a cure for cancer by giving 'screensaver time' from their computers to the world's largest ever computational project, which will screen 250 million molecules for cancer-fighting potential.

The project is being carried out by Oxford University's Centre for Computational Drug Discovery - a unique 'virtual centre' funded by the National Foundation for Cancer Research (NFCR), which is based in the Department of Chemistry and linked with international research groups via the world-wide web - in collaboration with United Devices, a US-based distributed computing technology company, and Intel, who are sponsoring the project.

Update: On Friday 27 April the Screensaver Project finally came to a close. The project, developed with the National Foundation for Cancer Research has run for six years and has at various times been funded by Intel, Microsoft and by IBM, but was chiefly a collaboration with United Devices Inc of Austin Texas.

It has been an enormous success, involving over 3.5 million personal computers in more than 200 countries. Only the SETI [Search for Extraterrestrial Intelligence] project has had more participants, but none has involved as much data transmission as this research.

The project built a database of billions of small drug-like molecules with known routes to synthesis. These compounds have been screened virtually to see if they might make potent inhibitors of proteins of known crystal structure and biological significance.

Conjuring Crystals

This is interesting. NASA scientists are examining a seemingly magical way to produce high-quality crystals.

Perhaps a NASA laboratory is an unlikely setting for a magic show. Nevertheless, this is where Frank Szofran and colleagues are growing high-quality crystals using a method as amazing as any conjuring trick. By carefully cooling a molten germanium-silicon mixture inside a cylindrical container, they coax it into forming a single large and extraordinarily well-ordered crystal. Such crystals have very few defects because, remarkably, they never touched the walls of the very container in which they grew.

Buckyballs clue to mass extinction 250 million years ago

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.

Interacting with molecules on the WWW

There are many chemical web pages that display chemical structures within the web page itself. You, the viewer can then rotate the molecule on screen, read off bond lengths and angles, and do other useful things. To do this, a free piece of software known as a plug-in is required.

There are at least two plugins available for you to use. In practice you will probably need both since they have different abilities and chemistry web site authors often cater for one rather than the other. Both are available for Macintoshes as well as PCs and bother are free.

The first available is known as Chime. On a Mac you have to use a NetScape browser in Classic mode while on a PC either NetScape or Internet Explorer is OK. The features available for Chime under MacOS and Windows differ unfortunately.

The second available is known as the Chem3D Net Plugin. On Macs and PCs either NetScape or Internet Explorer is OK.

Remember, some of what Chime can do, the Chem3D Net Plugin can not, and vice versa, so I suggest you get both (they are free). Many pages in WebElements benefit from these plugins, so get them and give them a try.

Note: links updated December 2009. The Chem3D Net Plugin seem to be available no longer.

Element 118 discovery retracted

The team of Berkeley Lab scientists that announced two years ago (1999) the observation of what appeared to be Element 118 (heaviest undiscovered transuranic element at the time) has retracted its original paper after several confirmation experiments failed to reproduce the results. This means that the pages for element 118 and parts of the data for element 116 are wrong.

WebElements: the periodic table on the WWW [http://www.webelements.com/]

Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.