Tuesday, January 10, 2012

New materials remove carbon dioxide from smokestacks, tailpipes and even the air

Scientists are reporting discovery of an improved way to remove carbon dioxide -- the major greenhouse gas that contributes to global warming -- from smokestacks and other sources, including the atmosphere. Their report on the process, which achieves some of the highest carbon dioxide removal capacity ever reported for real-world conditions where the air contains moisture, appears in the Journal of the American Chemical Society.

Alain Goeppert, G. K. Surya Prakash, chemistry Nobel Laureate George A. Olah and colleagues explain that controlling emissions of carbon dioxide (CO2) is one of the biggest challenges facing humanity in the 21st century. They point out that existing methods for removing carbon dioxide from smokestacks and other sources, including the atmosphere, are energy intensive, don't work well and have other drawbacks. In an effort to overcome such obstacles, the group turned to solid materials based on polyethylenimine, a readily available and inexpensive polymeric material.

Their tests showed that these inexpensive materials achieved some of the highest carbon dioxide removal rates ever reported for humid air, under conditions that stymie other related materials. After capturing carbon dioxide, the materials give it up easily so that the CO2 can be used in making other substances, or permanently isolated from the environment. The capture material then can be recycled and reused many times over without losing efficiency. The researchers suggest the materials may be useful on submarines, in smokestacks or out in the open atmosphere, where they could clean up carbon dioxide pollution that comes from small point sources like cars or home heaters, representing about half of the total CO2 emissions related to human activity.

Story Source:

The above story is reprinted from materials provided by American Chemical Society.

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

Journal Reference:

Alain Goeppert, Miklos Czaun, Robert B. May, G. K. Surya Prakash, George A. Olah, S. R. Narayanan. Carbon Dioxide Capture from the Air Using a Polyamine Based Regenerable Solid Adsorbent. Journal of the American Chemical Society, 2011; 133 (50): 20164 DOI: 10.1021/ja2100005

Plasma treatment zaps viruses before they can attack cells

 Adenoviruses can cause respiratory, eye, and intestinal tract infections, and, like other viruses, must hijack the cellular machinery of infected organisms in order to produce proteins and their own viral spawn. Now an international research team made up of scientists from Chinese and Australian universities has found a way to disrupt the hijacking process by using plasma to damage the viruses in the laboratory environment, before they come into contact with host cells.

The researchers prepared solutions containing adenoviruses and then treated the samples with a low-temperature plasma created by applying a voltage to a gaseous mixture in a syringe. The strong electric field energized electrons that collided with molecules in the gas, generating charged particles and highly reactive species such as oxygen atoms that likely etched away the protein shell of the viruses and damaged or destroyed the viral DNA. When the virus solutions were later added to colonies of embryonic kidney cells, the plasma-treated samples showed much less viral activity, as measured by the amount of a florescent virus protein the infected kidney cells produced. If the virus solution was covered during treatment to maximize plasma-virus interactions, more than 99 percent of the viruses could be deactivated in eight minutes.

The technique is described in a paper accepted for publication in the AIP's journal Applied Physics Letters.

Adenoviruses pose life-threatening risks to patients undergoing stem-cell therapy, so the anti-viral plasma treatment may help pave the way to safer therapies, the researchers write. Because plasma jets have multiple biomedical applications, the team is also developing a portable device that generates plasma by using a 12 V battery to decompose and ionize air, says Dr. XinPei Lu at the HuaZhong University of Science and Technology in China and leader of the team. The device might be used in rural areas and battlefields, according to Lu.

Story Source:

The above story is reprinted from materials provided by American Institute of Physics.

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

Journal Reference:

Jun Huang, Hui Li, Wei Chen, Guo-Hua Lv, Xing-Quan Wang, Guo-Ping Zhang, Kostya Ostrikov, Peng-Ye Wang, Si-Ze Yang. Dielectric barrier discharge plasma in Ar/O2 promoting apoptosis behavior in A549 cancer cells. Applied Physics Letters, 2011; 99 (25): 253701 DOI: 10.1063/1.3666819

Note: If no author is given, the source is cited instead.

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 . 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 ,” 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)

Deciphering the mechanism of an ion pump

Adenosine triphosphate (ATP) is the primary energy ‘currency’ within cells, and numerous enzymes are powered by the metabolic processing of this molecule via a mechanism known as hydrolysis. V-ATPases can exploit this process to pump positively charged ions across . This process occurs at the junction between a rotating ‘K’ domain and a fixed ‘a’ domain within the segment of the protein that resides at the cell membrane, although the specifics remain unclear. 

N,N’-dicyclohexylcarbodiimide (DCCD), a chemical that selectively reacts with a specific glutamate amino acid (E139) within the sodium-binding pockets of the K ring, proved valuable in assessing this protein’s function. The researchers demonstrated that DCCD inhibited binding by nearly 30-fold, but that this inhibition was sharply reduced when the enzyme was pretreated with sodium , suggesting that the two molecules interact with overlapping targets within the ring.

The K ring is composed of ten identical subunits, and DCCD efficiently reacts with E139 in each of these individual components (Fig. 1). By gathering structural data from the DCCD-treated V-ATPase, Murata and colleagues obtained a snapshot of what the protein looks like in the absence of sodium, which they could in turn compare against the structure of the sodium-bound form. 

Although the two structures were largely similar, DCCD treatment triggered a change in E139 that locked the sodium binding sites into an ‘open’ structure that prevented ion retention. The negative charge of E139 made an important contribution to the binding of the positively charged Na+ ion; DCCD appeared to work by neutralizing this charge. The researchers hypothesize that a similar process governs ion release during the transport process; as the K domain rotates, each subunit’s E139 interacts with a positively charged amino acid on the domain, triggering ion release and transfer across the membrane.

Confirming this model will require additional structural data. “We would like to obtain the structure of [the] whole complex containing both the rotor ring and a-subunit,” Murata says. Nevertheless, these findings could prove immediately applicable to the development of more effective ATPase inhibitors, a class of drugs potentially useful for treating cancer and other diseases. “V-ATPases are of considerable pharmacological interest,” says Murata.

More information: Mizutani, K., et al. Structure of the rotor ring modified with N,N’-dicyclohexylcarbodiimide of the Na+-transporting vacuolar ATPase. Proceedings of the National Academy of Sciences 108, 13474–13479 (2011).

Provided by RIKEN (news : web)