RSC - Advancing the Chemical Sciences


Chemistry World

 

News in brief



Ocean hydrocarbons made from rocks  

Researchers investigating 60-metre high carbonate chimneys in the Atlantic Ocean - the so-called 'Lost City' deep ocean vent field - have discovered that hydrocarbons seeping out from the vents don't come from a biological source such as bacteria, plants or animal matter.  

Instead, say Giora Proskurowski from the University of Washington, US, and colleagues publishing in Science  (DOI: 10.1126/science.1151194), inorganic carbon leaching from surrounding sea-floor rock (which has risen from the Earth's mantle) combines with hydrogen, heat and water to make the hydrocarbons. These Fischer-Tropsch style reactions have been shown to be plausible in the laboratory, but the team is the first to find consistent evidence for the effect in situ on the ocean floor, co-author Gretchen Früh-Green, of the Swiss Federal Institute for Technology (ETH), told Chemistry World

There's not enough evidence, though, to substantially rewrite the familiar story that fossil fuels are formed from the carbon in compressed plant and animal matter, said Früh-Green. 'We haven't done the calculations to suggest whether hydrocarbons originate more from mantle-derived rocks than from a biological source like organic-rich sediments or methane hydrates. It will be hard to honestly quantify,' she said.

More bad news for biofuels  

Most biofuels increase greenhouse gas emissions because clearing grassland or forest to plant them releases carbon dioxide, two groups of US researchers have independently concluded.  

The new analyses, published in Science  (DOIs: 10.1126/science.1152747; 10.1126/science.1151861) show that large amounts of trapped carbon are released into the atmosphere when vegetation burns or decays as land is cleared. This up-front 'carbon debt' can take centuries to claw back via emissions gradually avoided by using biofuels instead of fossil fuels.  

Using existing cropland to grow biofuels doesn't help, because farmers would clear more forest and grassland to replace crops - thus indirectly releasing sequestered carbon into the atmosphere. 

Both direct and indirect carbon debts have been routinely noted in previous papers analysing biofuel emissions savings, but the problem had not been quantified before, so tended to be eclipsed by headline figures. The US researchers said that only biofuels made from waste products or grown on abandoned lands do less harm than good. 

Microsoft ventures into e-chemistry 

Computational chemists have secured funding from computing giant Microsoft to showcase how chemistry can benefit from open access data sharing on the internet.  

The two-year eChemistry  pilot project represents 'a major test case' for proposed new protocols for sharing scholarly information over the web, said Lee Dirks, director of scholarly communications at Microsoft Research. Chemists across six institutions will search and index existing online databases and print archives, and work out how best to record data captured in lab experiments, so that disparate sources of information about molecules become machine-readable and searchable. 

Hungry pests gain GM resistance

Moth larvae called bollworms have become the first insects to develop resistance to Bt cotton, a crop genetically modified to produce insecticides called Bt toxins (named after Bacillus thuringiensis  bacteria).  

Bt cotton and corn have been grown worldwide since 1996. But despite this widespread use, only certain populations of bollworms in Mississippi and Arkansas have so far evolved any resistance, scientists at the University of Arizona, US, reported. Five other major pest species are yet to become resistant, said Bruce Tabashnik and colleagues, publishing in Nature Biotechnology  (DOI: 10.1038/nbt1382). 

Bt crops incorporate genes from Bt bacteria, which produce the toxins naturally. As the Bt toxin family includes hundreds of compounds, this diversity should ensure at least a few generations of GM crops before pests become entirely resistant, Tabashnik added. 

Graphene sheets with less flap 

US and Australian researchers have announced easier ways to make graphene - the strong, atom-thin carbon sheets that stack to make graphite. 

A team at the University of Wollongong, New South Wales, reported in Nature Nanotechnology  (DOI: 10.1038/nnano.2007.451) that graphene sheets peeled from graphite oxide can be stopped from clumping together in aqueous solution by electrostatic repulsion, when experimental conditions maximise negative charge on the sheets. This trick means chemical stabilisers, which prevent easy integration of graphene into films and coatings, aren't needed.  

And a Stanford University team reported in Science  (DOI: 10.1126/science.1150878) that layers of graphene loosened from graphite could be broken up into nanoribbon strips using ultrasound. The ribbons made this way had much smoother edges than those produced by traditional lithographic methods.

Bisphenol A row heats up 

New studies on the dangers of bisphenol A (BPA), a component of many plastics, have reanimated concerns that the chemical may harm children's health. The US National Toxicology Program's Center for the Evaluation of Risks to Human Reproduction (CERHR) is currently pondering the question, and expects to publish its final declaration in summer 2008. Its panel has found 'some concern' of risks to children's brain development at typical BPA exposures, but negligible worry of reproductive effects (see Chemistry World, September 2007, p8).  

But the CERHR panel ignored literature studies that injected BPA into animals' bloodstreams is irrelevant to the oral exposure expected for humans. That dismissal has been challenged by US scientists, who reported in Reproductive Toxicology  (DOI: 10.1016/j.reprotox.2008.01.001), that all routes of exposure cause similar BPA levels in baby mice.  

And University of Cincinnati scientists have further stoked public concern, reporting in Toxicology Letters  (DOI: 10.1016/j.toxlet.2007.11.001), that when plastic bottles are heated in a microwave or filled with boiling liquids, they release BPA more quickly. Release rates were nanograms per hour, but the researchers said a hormone disruptor such as BPA might have effects on newborn babies even at these exposure levels.  

Metals' laser facelift

Scientists from the University of Rochester, US, have transformed metals to look like gold. There's no alchemy involved, but no paint either: the researchers used femtosecond laser pulses to melt nanoscale structures into metal surfaces. These selectively reflected incoming light to make metals such as aluminium, platinum and titanium appear blue, gold, purple, and black, the team reported in Applied Physics Letters  (DOI: 10.1063/1.2834902). They are still working on red and green.  

Lead author Chunlei Guo said possibilities were endless: 'a cycle factory using a single laser to produce bicycles of different colours; etching a full-colour photograph of a family into the refrigerator door; or proposing with a gold engagement ring that matches your fiancée's blue eyes.' But the transformation is power-hungry, expensive and slow - it takes about 30 minutes to alter an area the size of a dime - so lovers of coloured jewellery should stick with real gold, or proven coatings, for now. 

Wellcome spending boost 

The Wellcome Trust, the UK's largest independent funder of medical research, has announced plans to increase its spending from £2.4 billion over the past five years to £4 billion over the next five. The extra money will go to large projects such as the planned UK centre for medical research and innovation, and programmes to translate genetic discoveries into treatments. Brain disorders and mental illness were priorities, said the charity's director, Mark Walport. Wellcome also aims to strengthen medical research capacity in Africa.  

Tighter mercury controls demanded 

The US Environmental Protection Agency (EPA) must rework its programme designed to control mercury emissions from coal-burning power plants, a US federal court has ruled.  

In 2005 the EPA had exempted coal plants from having to install mercury-reduction equipment under the Clean Air Act - instead preferring the flexibility of a 'cap-and-trade' programme that would allow utilities to swap rights to emit mercury to comply with a national limit. But following a lawsuit from 14 states, the EPA's rules will have to be more stringent. The years it will take to enact new laws mean individual states' strict limits on mercury emissions will hold in the meantime.