Materials science reveals clues about pigment degrading on painting

Unlike anything that came before it, with its shocking colors and radical spatial distortion, the painting caused an uproar among French audiences when it was first shown in 1906, according to Martha Lucy, associate curator at the Barnes Foundation.

Matisse used a lot of vibrant yellows in the work, also known as The Joy of Life, particularly a warm yellow made from cadmium sulfide. Unfortunately, portions of the painting containing cadmium sulfide are turning, alternately, white or brown, degrading the work, which is part of the Barnes Foundation collection.

University of Delaware Prof. Robert L. Opila is collaborating with Barbara Buckley, head of conservation at the Barnes, and Jennifer Mass, a senior scientist and head of the Scientific Research and Analysis Laboratory at Winterthur, to study the paint’s material microstructure and attempt to determine why the cadmium sulfide is changing color.

“It is a very disheartening phenomenon, considering the painting’s position in history,” says Opila, professor of materials science at UD.

“The work is known to have invigorated fellow artists, especially Pablo Picasso, who, in an effort to outdo Matisse in terms of shock value, immediately began work on his watershed Les Demoiselles D’Avignon,” Lucy says.

Opila’s team is using X-ray Absorption Near Edge spectroscopy (XANES), sharply focused high energy light similar to that used in hard X-rays, to deeply penetrate the microscopic paint chip’s layers and map the material’s chemical composition. The paint chips are tiny, measuring only about a micron, or a millionth of a meter in diameter.

Near edge means “you get wiggles near the absorption edge – where the light is first absorbed,” explains Opila, which tells scientists about the chemical state of the cadmium material and the materials to which it is chemically bound.

Preliminary test results conducted by UD doctoral student Jonathan Church at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, reveal that the cadmium sulfide is deteriorating to cadmium carbonate, which is white. There is also a consistent presence of chloride in the painting, which, Church suspects, is acting as a catalyst. Additionally, carbon dioxide is reacting with the cadmium and forming cadmium carbonate.

“It looks like the presence of chloride is important,” says Church.

While Opila and his research team are not yet sure where the sulfide is going; they theorize that the binder, a drying oil like linseed oil, may be turning brown.

The challenge now involves analyzing the data and developing methods to prevent further degradation of the painting. The Barnes will use this information to determine what kind of light exposure and humidity is advisable, and whether other measures, such as dimming shields, are needed to protect the work.

“The scientific studies being undertaken will contribute significantly to the preservation of the painting and to our understanding of the change that has taken place to the visual appearance of the painting,” says Buckley. 

Another question is whether science can convert the white and brown materials back to their original yellow form as cadmium sulfide. Opila believes it’s unlikely, and says it may even be unadvisable to attempt.

“There is huge philosophy at play here because if you have a work of art that degrades over time – is the work of art the original piece or the time-integrated work of art,” Opila remarks, then continues, “We may want to slow the rate of change, but I’m not sure we’d want to change it back, even if we could.”

Discoveries made in this project may someday impact other post-impressionist and early modern works.

“Van Gogh’s paintings also feature a large amount of cadmium sulfide-based yellow,” Opila says.

Provided by University of Delaware (news : web)

New solar-powered classroom brings science to schools in developing countries

 An innovative project led by a chemistry academic at the University of Southampton is using solar generators to provide IT resources and 'hands-on' science for students in developing countries.

A major difficulty in teaching science subjects in developing countries, especially in rural schools, is that students are rarely able to get 'hands-on' experience of experiments. This could be partly due to a lack of equipment, chemicals and facilities but mainly because of a lack of electricity and running water.

Now, Professor Tony Rest, a visiting Chemistry academic at the University of Southampton, and Keith Wilkinson, formerly a teacher at the International School at Lusaka in Zambia, have devised a solar-powered solution based on a digital projector and low-cost solar energy panels so that students can gain access to IT and other modern teaching methods.

Professor Rest says: "The lack of electricity is a particularly serious matter for rural schools and this situation is unlikely to get better in the near to medium future. With drawbacks to petrol generators, due to difficulties in getting supplies and safety hazards, solar energy generators have become available at cost-effective prices and provide a sustainable answer as rural schools have an abundance of the basic energy source required to power them -- sunshine.

Most data/video projectors require 200-300 watt and cannot be economically sustained by solar power in rural villages. However, the advent of mini-projectors, which require about 50 watts of power, has revolutionised the situation and made battery powered projection feasible.

The solar energy generators, which consist of solar panels, batteries and inverters, can be linked to the projector for students to get practical classes via multimedia resources to show laboratory experiments and stress practical techniques.

Professor Rest adds: "These experiences can be extended to other science subjects from physics, biology and maths, to subjects involving practical elements, such as engineering, and to craft subjects, including plumbing, carpentry, and catering, where students need see how to acquire skills. By extending the breadth of subjects benefiting from the use of IT, the overall cost of using a solar energy generator is reduced. Another spin-off is that students in rural schools gain access to valuable IT skills."

The project has been developed by the 'Chemistry Aid' project, the Chemistry Video Consortium based at the University of Southampton, with support from the Royal Society of Chemistry, which has provided multimedia teaching resources.

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The above story is reprinted from materials provided by University of Southampton.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Biology, materials science get a boost from robust imaging tool: Collaborators give a new view of macromolecular systems

Shape and alignment are everything. How nanometer-sized pieces fit together into a whole structure determines how well a living cell or an artificially fabricated device performs. A new method to help understand and predict such structure has arrived with the successful use a new imaging tool.

Coupling laser-driven, two-dimensional fluorescence imaging and high-performance computer modeling, a six-member team -- led by University of Oregon chemist Andrew H. Marcus and Harvard University chemist Alan Aspuru-Guzik -- solved the conformation of self-assembled porphyrin molecules in a biological membrane.

Porphyrins are organic compounds that are ubiquitous in living things. They carry mobile electrical charges that can hop from molecule-to-molecule and allow for nanoscale communications and energy transfer. They are also building blocks in nanodevices.

The new technique -- phase-modulation 2D fluorescence spectroscopy -- is detailed in a paper scheduled to appear online this week ahead of regular publication in the Proceedings of the National Academy of Sciences. The breakthrough skirts the often-needed step of obtaining crystals of molecules that are being studied, said Marcus, a member of the Oregon Center for Optics, Materials Science Institute and Institute of Molecular Biology. Most functional biological molecules don't easily form crystals.

"Our technique is a workable way to determine how macromolecular objects assemble and form the structures they will in biological environments," Marcus said. "It's robust and will provide a means to study biological protein-nucleic acid interactions."

Work already is underway to modify the experimental instrumentation in the UO's stable and temperature-controlled High Stability Optics Lab to apply the research on DNA replication machinery -- one category of the best-known macromolecular complexes, which consist of nucleic acids and proteins that must be properly aligned to function correctly. "It's a strategy that will allow us to do two things: Look at these complexes one molecule at a time, and perform experiments at short ultraviolet wavelengths to look at DNA problems," he said.

In addition, the approach should be useful to materials scientists striving to understand and harness the necessary conformation of polymers used in the production of nanoscale devices. "In biology, large molecules assemble to form very complex structures that all work together like a machine," Marcus said. "The way these nanoscale structures form and become functional is an actively pursued question."

The technique builds on earlier versions of two-dimensional (2D) optical spectroscopy that emerged in efforts to get around limitations involved in applying X-ray crystallography and nuclear magnetic resonance to such research. The previous 2D approaches depended on the detection of transmitted signals but lacked the desired sensitivity.

The new approach can be combined with single-molecule fluorescence microscopy to allow for research at the tiniest of scales to date, Marcus said. "With fluorescence, you can see and measure what happens one molecule at time. We expect this approach will allow us to look at individual molecular assemblies."

Oregon Nanoscience and Microtechnologies Institute (ONAMI), the National Science Foundation and U.S. Department of Energy supported the research. Marcus is a researcher in ONAMI, a collaboration involving the UO, Oregon State University, Oregon Health and Science University, Portland State University, the Pacific Northwest National Laboratory, the state of Oregon and private industry.

The laboratory where the laser work opened in 2005, built with a $510,500 grant from the M.J. Murdock Charitable Trust and a $600,000 investment by the UO. Initially named the Laboratory for Quantum Control as part of the UO's Center for Optics, the basement lab allows researchers to probe and control the behavior of atoms, semiconductors and nanometer-thin metal films.

Geoffrey A. Lott, who earned a doctorate at the UO and is now with Boise Technology Inc. in Nampa, Idaho, and Alejandro Perdomo-Ortiz, a doctoral student in Harvard's department of chemistry and chemical biology, were lead authors on the paper. Additional co-authors were James K. Utterback, an UO undergraduate student in physics and 2009 Barry M. Goldwater Scholarship recipient, and Julia R. Widom, a UO doctoral student and a 2010 recipient of a Rosario Haugland Chemistry Graduate Research Fellowship.

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

Academia vs. Alternative Science Careers—What’s the deal?

“Bart, don’t make fun of grad students, they just made a terrible life choice.” –Marge Simpson

This post is an outpouring of my thoughts and feelings about the whole “academia vs. alternative career” dilemma, arranged into lists to make them appear to have some level of organization. Take a look and let me know what you think!

Alternative careers aside, what are some of the things that make grad students decide against academia (anything but academia!):

I got caught in a bad project and want out… forever. (d “I want good data and a paper in Cell but I got a project straight from hell… whoa oh ohhhhh, caught in a bad project.” d) Great, now I have that song stuck in my head.I may not have had a bad project but my labmates were such meanies that I developed an aversion to all things research. (What, you mean it wasn’t funny when we wrapped all the items on your desk in foil and filled your desk drawers with packing peanuts when you were gone on vacation?)I married rich and will live off the income of my sugar-spouse.I like my life too much to sign it all away to the ever-growing list of academic responsibilities: research, grant writing, teaching, administrative stuff, meetings, recruiting, advising, group meetings, subgroup meetings, one-on-one meetings, conferences, writing papers (publish or perish!) and frequent world travel. Exciting for a single person without kids, not so much for someone who wants to actually see their spouse/family on occasion.I don’t want to put in ten years of schooling to get a job making marginally more per hour than the average person.I want to actually have kids before their child-bearing abilities have left me without a trace. I know, you can have kids before tenure, but from what I hear it makes it a lot harder (not surprising), especially if you don’t have a stay-at-home spouse.I don’t want to give up all my other hobbies forever and ever in the name of being a hard-core academic. Yes, this is an actual photo from the lab I work in. Photo credit: Nicole V. Tolan

Which leads me to… what’s the appeal of an “alternative career” in science?

Working a job that you love and that combines multiple interests and passions into one (i.e. science and writing, medicine and art, technology and law, you get my drift).Having an 8-to-5 job so that you can make time for the rest of your life. All those hobbies that got put on hold when grad school happened, you can get them back again!The option of moving around. You have heard it said that once you leave academia it’s hard to come back (although some argue against that). However, with an alternative career you may find yourself shifting gears over the years and end up doing something completely different from what you started off doing.The option of freelance. Just imagine: working in your pajamas from your cozy at-home office. No more driving through traffic or wearing sausage casings (a.k.a. pantyhose). Sure, it has its own set of pressures and challenges, but… just imagine…

What’s the take-home message? In my opinion, academia would be much more appealing if it wasn’t so gosh-darn demanding. I really believe that I would want to become a professor if the amount of work they had to do in one day was split up over three. That is, if I hadn’t recently fallen out of love with research.

I just think it’s too bad that the unreasonably high demands that are put on professors turn so many good professor candidates away from academia. Just sayin’…

View the original article here

Science looks to poplar trees for 'cool roof' technology

For as long as humans have been able to reason, they have mimicked nature in attempts to derive benefits for themselves; and just because we’ve become ultra-high tech in many ways, it doesn’t mean we’ve stopped looking to nature to help us solve some of the problems that continue to arise in our paths. As one example Yanlin Song and others on a team doing research for the Chinese Academy of Science, as described in their paper "Highly reflective superhydrophobic white coating inspired by poplar leaf hairs toward an effective 'cool roof'" in Energy & Environmental Science, are copying the way poplar trees protect themselves from harsh sunlight and believe it might lead to new ways to help control the heat that is produced when sunlight beats down on a roof.

The idea is simple, the poplar tree, over eons, has developed micro-fibers on the undersides of its leaves that can reflect both light and heat from the sun; thus, when the sun shines directly on the tree, it turns its leaves upside down to protect the insides of the leaves from extreme heat and the ensuing loss of moisture.

The Chinese team has been working on spinning polymers into long protective hollow fiber coatings that could in theory reflect sunlight, and thus reduce the amount of heat that is absorbed when sunlight shines on a roof. To test their results, they covered a swath of material with diarylethene, a compound that changes color when heated, then covered that with their polymer film, and then let the sun shine. They found that the more closely they could emulate the structure of the natural fibers on the poplar leaves, the less the diarylethene changed color.

And while the results the team has managed to show so far are promising, there is still a pretty serious obstacle standing in the way of developing a commercial product that could help homeowners or businesses cut their summer cooling costs; the polymers are just not resistant enough to stand up to the constant barrage of heat, cold, wind and other weather conditions.

Song says he and his team will continue to work with the polymers to see if they can come up with something stronger but will also continue with what they've developed thus far, perhaps even branching out in to other areas, such as lighting applications or in developing waterproofing substances since their polymer film turned out to be water resistant as well.

More information: Highly reflective superhydrophobic white coating inspired by poplar leaf hairs toward an effective "cool roof", Changqing Ye, Mingzhu Li, Junping Hu, Qunfeng Cheng, Lei Jiang and Yanlin Song, Energy Environ. Sci., 2011, Advance Article. DOI:10.1039/C0EE00686F

 

The science of spring: Plants rely on internal alarm clocks to tell them when to wake up from winter

Just in time for the birds and the bees to start buzzing, the flowers and the trees somehow know when to open their buds or start flowering. But the exact way that plants get their wake-up call has been something of a mystery.

"Why should plants care?" The general answer to that is that there are a lot of situations where it’s important not to do something developmentally until spring has arrived," said Richard Amasino, a professor of biochemistry at the University of Wisconsin Madison. "Trees want to make sure that their buds are protected until spring."

Sibum Sung, a molecular biologist at the University of Texas Austin has an idea of how this protective action works on a cellular level. He discovered a special molecule in plants that gives them the remarkable ability to recall winter and to bloom on schedule in the spring. Sung published his results last December in the journal Science Express.

While digging through the DNA of a small cabbage-like plant called Arabidopsis, Sung and a colleague discovered that the production of a special molecule could be turned on or off by a string of genetic material. When the plant gets cozy for the winter, this molecule is not produced, repressing a plant’s ability to create flowers. But after 20 days of consistently frigid weather, production of the molecule gets turned back on, signaling another gene to stop repressing flower production and start preparing for spring. The plant takes another 10-20 days to prime itself for warmer temperatures. Without the 20 days of freezing temperatures, the molecule wouldn't be produced -- even if there is a brief spike in the thermometer reading.

Sung hypothesized that over millions of evolutionary years, this molecule -- called COLDAIR -- has created a sort of cellular memory in generations of plants, letting them know that a month of winter has come and gone, and now they can start preparing for the spring.

Of course, mysteries remain. Sung admits that his team is still working on questions like how the plant knows that temperatures have been low for at least 20 days.

"Well, we know that there are several things done by cold -- but how? That we don't really know yet," Sung said.

The genetic pathways involved are different for each type of plant, said Amasino, but the kind of alarm clock memory is similar. The reason may have to do with the early evolution of plants.

"Flowering plants had already evolved and changed 150 million years ago, when the Earth was a pretty different place," Amasino said. At that time, the Earth was much warmer, and the Atlantic Ocean didn't even exist yet. "So it's relatively recently that plants had to contend with winter," he said.

The kind of responses that plants developed to cold over the past hundred million years happened independently, said Amasino -- and that is one reason that different plants have unique systems to deal with wintertime. "One aim of plant research for the future is to explore how these systems evolved in different plant species," Amasino said.

When the planet’s climate changes more rapidly, it can sometimes be difficult for plants to keep up. Researchers have been studying plants that are opening earlier in the season, according to Ove Nilsson, a professor at the Umea Plant Science Centre in Umea, Sweden. He said that another problem with early spring is that plants get out of sync with their insect pollinators.

"This could potentially be catastrophic for the plants since these flowers can freeze to death," said Nilsson.

But as long as there is winter, nature will keep the pressure on to set an alarm clock for springtime, and the plants will once more open up.

More information: Vernalization-Mediated Epigenetic Silencing by a Long Intronic Noncoding RNA, Science 7 January 2011: Vol. 331 no. 6013 pp. 76-79. DOI: 10.1126/science.1197349

Provided by Inside Science News Service (news : web)

Science review casts doubt on 2001 anthrax case (Update 2)

There was insufficient scientific evidence to support the FBI's assertion that anthrax sent to politicians and journalists in the wake of the September 11 attacks originated in Ivins' lab, said the National Academy of Sciences.

"It is not possible to reach a definitive conclusion about the origins of the B. anthracis in the mailings based on the available scientific evidence alone," said the NAS report.

The anthrax mailings, which killed five people and injured 17, rattled an already jittery American public just days after Al-Qaeda militants hijacked passenger jets and plunged them into the World Trade Center and the Pentagon.

The review found that anthrax contained in a flask, known as RMR-1029, in Ivins' lab shared genetic similarities with spores in the mailed letters but "was not the immediate source of spores used in the letters."

"One or more derivative growth steps would have been required to produce the anthrax in the attack letters," the report said, adding that the letters sent to Washington had different characteristics than those sent to New York.

"They have enough physical and chemical differences between the two that they must have come from separate batches," said lead author of the report Alice Gast.

The FBI concluded that the mailed anthrax must have come from a single flask of parent spores that Ivins had created and which he alone had maintained.

The type of anthrax contained in the letters, mailed to NBC anchor Tom Brokaw, the New York Post and senators Tom Daschle and Patrick Leahy, was correctly identified as the Ames strain of B. anthracis, which originated from a cow in Texas in 1981 and was shared with labs worldwide, the report said.

But a key problem arose from the way the FBI attempted to narrow down the source of the anthrax by creating a repository of potential samples provided by the labs that maintain them.

The repository was incomplete, leaving the possibility that other sources could remain unexamined, and also relied on scientists to provide their own samples, allowing for manipulation by potential suspects.

"Standards of custody of evidence would dictate that agents of the FBI should have obtained the samples," the report said.

"The sender could have been the instigator and may not have complied with instructions, as the FBI alleges with respect to Dr. Ivins."

Ivins, a bio-defense researcher at the US Army's Medical Research Institute of Infectious Diseases, committed suicide by taking drugstore medications in July 2008 as FBI agents were about to bring charges against him.

Investigators began focusing on Ivins in 2007 after new forensic scientific methods traced the anthrax back to him.

The NAS report was delayed in November 2010 when the FBI, which had just received the final draft for security review, decided to release more, previously classified information for the panel to consider.

FBI investigators had looked at anthrax evidence from "an undisclosed overseas site at which a terrorist group's anthrax program was allegedly located," the report said.

"The information indicates that there was inconsistent evidence of Ames strain DNA in some of these samples, but no culturable B. anthracis," it said, adding that the late-arriving information "deserves a more thorough scientific review."

The NAS reviewers also noted that their analysis of evidence was limited to "the biological, physical, and chemical sciences," and did not consider other traditional forensic science methods.

The FBI, which commissioned the NAS report, highlighted the panel's assertion that a definitive conclusion based on science alone "was not possible" and said a combination of factors led investigators to Ivins.

"The FBI has long maintained that while science played a significant role, it was the totality of the investigative process that determined the outcome of the anthrax case," it said in a statement.

Some lawmakers called for a new, independent probe of the government's response.

"The National Academy of Sciences report released today shows that the science is not necessarily a slam dunk," said Senator Chuck Grassley.

"There are no more excuses for avoiding an independent review and assessment of how the FBI handled its investigation in the anthrax case."

Congressman Rush Holt said he was re-introducing a 2008 bill to establish a legislative commission to investigate.