Thursday, August 13, 2009


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Wood science researchers at Oregon State University have made some surprising findings about the potential of microcrystalline cellulose – a product that can be made easily from almost any type of plant fibers – to partially replace silica as a reinforcing filler in the manufacture of rubber tires.

A new study suggests that this approach might decrease the energy required to produce the tire, reduce costs, and better resist heat buildup. Early tests indicate that such products would have comparable traction on cold or wet pavement, be just as strong, and provide even higher fuel efficiency than traditional tires in hot weather.

“We were surprised at how favorable the results were for the use of this material,” said Kaichang Li, an associate professor of wood science and engineering in the OSU College of Forestry, who conducted this research with graduate student Wen Bai.

“This could lead to a new generation of automotive tire technology, one of the first fundamental changes to come around in a long time,” Li said.

Cellulose fiber has been used for some time as reinforcement in some types of rubber and automotive products, such as belts, hoses and insulation – but never in tires, where the preferred fillers are carbon black and silica. Carbon black, however, is made from increasingly expensive oil, and the processing of silica is energy-intensive. Both products are very dense and reduce the fuel efficiency of automobiles.

In the search for new types of reinforcing fillers that are inexpensive, easily available, light and renewable, OSU experts turned to microcrystalline cellulose – a micrometer-sized type of crystalline cellulose with an extremely well-organized structure. It is produced in a low-cost process of acid hydrolysis using nature’s most abundant and sustainable natural polymer – cellulose – that comprises about 40-50 percent of wood.

In this study, OSU researchers replaced up to about 12 percent of the silica used in conventional tire manufacture. This decreased the amount of energy needed to compound the rubber composite, improved the heat resistance of the product, and retained tensile strength.

Traction is always a key issue with tire performance, and the study showed that the traction of the new product was comparable to existing rubber tire technology in a wet, rainy environment. However, at high temperatures such as in summer, the partial replacement of silica decreased the rolling resistance of the product, which would improve fuel efficiency of rubber tires made with the new approach.

More research is needed to confirm the long-term durability of tires made with partial replacement of silica, Li said. Further commercial development of this technology by a tire manufacturer could be undertaken at any time, he said. The newest findings were just published in a professional journal, Composites Part A: Applied Science and Manufacturing.

(Photo: OSU)

Oregon State University


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A new study of sea level fluctuations over the last 22,000 years is the latest to predict that rising seas could reach close to one meter by the end of this century, consistent with the most recent sea level projections made by the Intergovernmental Panel on Climate Change (IPCC).

The estimate, published July 26 in the journal Nature Geoscience, is not as dire as the three-meter (nine-foot) rise forecast by some scientists. But lead author Mark Siddall, who did the research at Columbia University’s Lamont-Doherty Earth Observatory and University of Bristol, UK, says the model’s worst-case scenario still spells major problems for some countries.

“The changes with one meter of sea level rise are drastic,” said Siddall, who is now based at Bristol. “The danger to low lying areas is still there. It floods a major part of Bangladesh as well as other low lying areas and it means coastal flood events will become much more common.”

Siddall and his colleagues in the United States and Switzerland combined data from fossil corals and ice cores to reach their conclusion. Toward the end of the last ice age, about 22,000 years ago, seas began a slow rise of some 120 meters, as the planet warmed. However, the warming was not continuous, and sometimes seas retreated. Records of ancient swings in temperature were preserved in air bubbles trapped in ice cores, and corresponding sea-level swings were preserved in coral fossils. By combining the measurements, Siddall and his colleagues tracked how sea levels correlated with temperatures, and predicted how seas might react to warming projections for the 21st century.

They forecast a sea-level rise of 7 to 82 centimeters (3 to 32 inches), in response to the minimum 1.1 degree C and maximum 6.4 degree C warming projections by the IPCC. Their sea-level prediction closely mirrors the IPCC’s own 2007 estimate of 18 to 76 centimeters (7 to 30 inches). The IPCC used sophisticated climate models to carry out its analysis, while Siddall and colleagues used a far simpler one to reach a similar result.

The seas do not respond immediately to temperature changes, said Siddall, so it may take hundreds of years before we see the full effects of the heat-trapping gases that people have put into the air since the start of industrialization. “Sea levels will be rising substantially,” he said. “And what we did last century will continue to affect sea levels for centuries and centuries.”

Placing limits on expected sea-level rise over the next century is one of the most pressing challenges for climate scientists, as large uncertainties surround the different methods used. One major problem is that the melting or collapse of the vast Greenland and Antarctic ice sheets could cause catastrophic rises, but their dynamics are not well understood. Siddall’s model takes into account these ice sheets but does not allow for the catastrophic, sudden collapse of the West Antarctic Ice Sheet--an assumption that has led some climate scientists to predict far greater increases.

“We can’t say what the impact of global climate change will be in New York or Great Britain or Switzerland but we can be sure that as the climate warms, sea level will rise,” said Lamont geochemist Steven Goldstein, who was not involved in the research.

(Photo: Montage, photo of Antarctic iceberg: Louise Newman, International Project Office of Past Global Changes. Photo of Belize coral: H. Allen Curran, Smith University)

Lamont-Doherty Earth Observatory


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A higher density of blood vessels and other unique physiological features in the flight muscles of bar-headed geese allow them to do what even the most elite of human athletes struggle to accomplish – exert energy at high altitudes, according to a new UBC study.

Named for the dark stripes on the backs of their heads, bar-headed geese are native to South and Central Asia. Often bred in captivity as domestic garden birds, they migrate annually in the wild between India and the high altitude plateaus in China and Mongolia, flying over the world’s highest mountains on their way.

“They fly at altitudes up to 9,000 metres,” says UBC Zoology PhD student Graham Scott. “That’s the equivalent of humans running a marathon at the altitudes commercial airlines fly.”

Scott and colleagues from UBC and the University of Birmingham in the UK compared the physiology of bar-headed geese to low-altitude waterfowl such as barnacle, pink-footed and greylag geese. Their findings are published today in the journal Proceedings of the Royal Society B: Biological Sciences.

“We found approximately six to 10 per cent more aerobic muscle fibres in bar-headed geese compared to low altitude birds,” says Scott. “There were also more capillaries – the body’s smallest blood vessels – surrounding these fibres in bar-headed geese.”

The team also found that the bar-headed geese’s mitochondria – the cell’s power sources – are distributed closer to the cell membrane and therefore closer to capillaries.

“These traits allow oxygen to be carried and diffused more effectively to the flight muscles,” says Scott. Since these physical traits are inherent even in bar-headed geese that are bred in captivity and have never flown, the researchers believe they’ve evolved over time specifically to survive and perform at high altitudes.

Scott had previously found that bar-headed geese also breathe more when oxygen is scarce than most other animals do, suggesting they are fine-tuned for flying high. These insights allow scientists to better understand the limitations of human physiology and potentially find ways to exceed them.





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