NSF turns to ancient pottery to improve modern heat resistant ceramics

In order for space vehicles to work properly, they have to be able to withstand the cold of space, which can be as low as 250 degrees Fahrenheit below zero. Then, some vehicles have to be able to withstand the extreme heat of reentry, which can be as hot as 3000 degrees. Hot enough to melt most any metal. As most know, the Space Shuttle was fitted with ceramic tiles on its underbelly to keep the vehicle from overheating as it came back to Earth, which was made all the more apparent when damage to the tiles resulted in the loss of Columbia in 2003. But ceramics are used in other components as well, and will be needed as more ambitious projects are undertaken in the future. Equally important is the ability of ceramics to remain chemically unchanged when subjected to such temperature variations. Such properties allow for the construction of components that minimize expansion and contraction under such stresses, which can be critical for long term operations in space. This is why the NSF has turned to research scientists to see if the ancient Greeks can provide some insight.

Such research will involve using something called x-ray absorption near edge structure (XANES) - which is a special type of spectroscopy, along with other types of x-ray techniques, to find out what has gone on with iron oxidation in the pottery under study. What’s needed is a better understanding of the molecular structure of iron minerals that were used to make the pottery to help researchers in designing newer and better types of ceramics for future space missions, whether manned or otherwise.

What’s interesting is that it is apparently the degree to which the iron in the ancient ceramic pottery oxidized that caused the distinctive red and black colorations that made it so attractive to those that worked with it all those years ago.

 

Unearthing the appearance of ancient animals: X-ray technique for determining fossil pigmentation patterns

An international team including University of Pennsylvania paleontologists is unearthing the appearance of ancient animals by using the world's most powerful X-rays. New research shows how trace metals in fossils can be used to determine the pigmentation patterns of creatures dead for more than a hundred million years.

The research was conducted by an international team working with Phillip Manning, an adjunct professor in the School of Arts and Sciences' Department of Earth and Environmental Science, and Peter Dodson, a professor in both the Department of Earth and Environmental Science and the School of Veterinary Medicine's Department of Animal Biology. They collaborated with Roy Wogelius of the University of Manchester, Uwe Bergmann of Stanford University's SLAC National Accelerator Laboratory and other researchers.

Their work will be published in the journal Science on July 1.

Manning and Dodson have long studied fossils of the earliest birds, including Confuciusornis sanctus, which lived 120 million years ago and was one of many evolutionary links between dinosaurs and birds, and Gansus yumenensis, which is considered the oldest modern bird and lived more than 100 million years ago. Their partnership with researchers from Manchester and Stanford, however, has opened a new avenue of investigation.

"Every once in a while we are lucky enough to discover something new, something that nobody has ever seen before," said Wogelius, a geochemist and the paper's lead author.

The team's discovery is rooted in a new technique, using technology based on synchrotron radiation to identify copper-bearing molecules in the fossilized feathers of these ancient birds.

"There is an intimate relationship between trace metals and organics. When you're getting a good suntan, melanin forms in your skin. There are many forms of melanin, and some are found in the dark feathers of birds, but copper is always bound into its structure," Manning said. "You can see this in living animals, but it's only since we've been using a synchrotron -- a vast accelerator that generates intense X-rays a hundred million times brighter than the sun -- that we can see the chemical detail in fossils and show that the copper complexes we found were originally part of the animal."

Metallic compounds can survive in these fossils for hundreds of millions of years because they are unpalatable to microorganisms. But to distinguish the copper that was bound in melanin with copper that might have been geochemically produced requires the precision that only a tool like the synchrotron can provide. By measuring the energy released by atoms when they are bombarded with high-powered X-rays, researchers can get an accurate picture of the molecules in which they reside.

"We're able to map absolute quantities, to parts-per-million levels in discrete biological structures, which we compare with living organisms and see they are comparable," Manning said.

The new technique paints a richer picture of the lives of these ancient creatures.

"While our work doesn't yet allow you to diagnose color, you can get the concentration and distribution of pigments," Dodson said. "In other words, you can work out monochrome patterns, which may tell us something about camouflage or other traits relevant to natural selection of the species."

"If we could eventually give colors to long extinct species, that in itself would be fantastic," said co-author Uwe Bergmann, deputy director of the Linac Coherent Lightsource at SLAC. "But synchrotron radiation has revolutionized science in many fields, most notably in molecular biology. It is very exciting to see that it is now starting to have an impact in paleontology, in a way that may have important implications in many other disciplines,"

The team is confident that further research with this technique will enable them to fully diagnose color via fossil chemistry, and they also believe that this is only one of many applications the technique will have.

"This synchrotron research is really important as it gives us the first clue to really understanding what happens with organic debris when you bury it in the ground," Manning said. "For example, there are huge implications for understanding the mass transfer of buried waste; trace metals can be bad if you get too much of them, so we can spatially map and give images of exact loadings of these metals in both living and extinct organisms. No one else can do this. It's not just contributing to a field, it's creating a whole new discipline."

In addition to Wogelius, Manning, Dodson and Bergmann, the research was conducted by Holly Barden, Nick Edwards and William Sellers, of Manchester University; Peter Larson of Manchester University and the Black Hills Institute of Geological Researc, Inc.; Kevin Taylor of Manchester Metropolitan University; Sam Webb of the SLAC National Accelerator Laboratory; Hai-lu You of the Chinese Academy of Geological Sciences; and Li Da-qing of the Gansu Geological Museum.

Support for this research was provided by the United Kingdom's National Environmental Research Council and an anonymous private donor.

Fossil samples were provided by the Black Hills Institute Museum and the Museum für Naturkunde, Humboldt University, Berlin. The Stanford Synchrotron Radiation Lightsource at SLAC is a Department of Energy Office of Science national user facility which provides synchrotron radiation for research in chemistry, biology, physics and materials science to more than a thousand users each year.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by University of Pennsylvania.

Journal Reference:

R. A. Wogelius, P. L. Manning, H. E. Barden, N. P. Edwards, S. M. Webb, W. I. Sellers, K. G. Taylor, P. L. Larson, P. Dodson, H. You, L. Da-Qing, U. Bergmann. Trace Metals as Biomarkers for Eumelanin Pigment in the Fossil Record. Science, 2011; DOI: 10.1126/science.1205748

Safer, more effective skin-whitening creams from ancient Chinese herbal medicine

Scientists today reported discovery of the active ingredients in an herb used in traditional Chinese medicine for skin whitening, changing skin color to a lighter shade. The ingredients are poised for clinical trials as a safer, more effective alternative to skin whitening creams and lotions that millions of women and some men use in Asia and elsewhere, they said. The report was among more than 9,500 presentations this week at the 241st National Meeting & Exposition of the American Chemical Society (ACS).

The finding, which caps an intense search for these natural skin lightening substances, could be a boon to women in Asian countries, said study leader Hui-Min Wang, Ph.D. He explained that skin whitening products are all the rage there, but too-often accompanied by itching, redness, inflammation, and other side effects.

"Toxic skin whitening creams are a growing threat to women's health, especially in Asia," Wang said. "We hope that our product will improve lives and provide a safer, more natural way to lighten skin. A cream based on these herbal ingredients could be available on store shelves in as little as a year."

Skin-whitening is big business in countries like China, Japan, Korea, and India, where many women view whiter skin as a symbol of beauty, good health, and high social status. One study estimates that half the women in Asian countries use skin lightening creams, spending the equivalent of several billion dollars annually. People also use such products to fade unsightly age spots, freckles, and scars that have collected pigment.

Dozens of skin whitening creams, lotions, and other products are on sale throughout Asia. Some products contain toxic mercury, hydroquinone, and other potentially toxic substances that can cause redness, itching, inflammation and other skin problems. Some whitening ingredients could increase the risk of skin cancer when used frequently and at high doses, Wang said, citing the need for safer, more effective alternatives.

Wang and colleagues say that they have found a promising alternative in the form of an herbal "cure-all" used in traditional Chinese medicine in the form of soup or tea. The evergreen bush, Cinnamomum subavenium, is a close relative of the trees whose inner bark is the source of cinnamon. The scientists isolated two chemicals from the plant that have the ability to block tyrosinase, an enzyme that controls the synthesis of melanin, a dark pigment responsible for coloring skin, hair, and eyes. Inhibiting tyrosinase is one of the major strategies for skin-whitening, Wang said.

They tested these so-called "melanogenesis inhibitors" on the embryos of zebrafish, which are widely used as stand-ins for people and other animals in biomedical research. The embryos contain a highly visible band of black pigment. Exposure to low levels of the two chemicals reduced melanin production in the fish embryos by almost 50 percent within just four days, turning the embryos snowy white, the scientists said.

"When we saw the results, we were amazed," said Wang, who is with Kaohsiung Medical University in Taiwan. "My first thought was, well, 'If these herbal whiteners can transform zebrafish embryos from black to white, maybe they can also lighten women's skin.'"

He estimated that the chemicals are 100 times more effective in reducing melanin pigmentation than the common skin whitening agents kojic acid and arbutin, which have been used in cosmetics for more than 30 years. The substances did not appear to be toxic when tested in low doses on both cultured human skin cells and zebrafish embryos, Wang noted.

Wang is looking forward to clinical trials of a new beauty product based on the ingredients. Just a one percent solution of the chemicals could achieve dramatic skin whitening, Wang said, adding that several cosmetic companies are working with his group. Wang and his colleagues have applied for patents in the U.S., Japan, and Taiwan.

Provided by American Chemical Society (news : web)