Wednesday, November 30, 2011

Fast new test for terrible form of food poisoning

Takeshi Yasumoto and colleagues explain that 20,000-60,000 people every year come down with ciguatera poisoning from eating fish tainted with a ciguatoxin -- the most common source of from a natural toxin. Fish, such as and sea bass, get the toxin by eating smaller fish that feast on that produce the toxin in tropical and , such as the Gulf Coast of the U.S. There's no warning that a fish has the toxin -- it smells, looks and tastes fine. But within hours of ingesting the toxin, people with ciguatera have symptoms that often include vomiting, diarrhea, numbness or tingling in the arms and legs and muscle and joint aches. Debilitating symptoms may last for months. The current test for the toxin involved giving it to and watching them for symptoms. It is time-consuming, may miss the small amounts present in fish, and can't tell the difference between certain forms of the disease. That's why Yasumoto's group developed a faster, more sensitive test.

They describe development of a new test, using standard laboratory instruments, that avoids those draw backs. Yasumoto's team proved its effectiveness by identifying 16 different forms of the toxin in fish from the Pacific Ocean. Clear regional differences emerged -- for example, snappers and groupers off Okinawa shores had one type, whereas spotted knifejaw captured several miles north of Okinawa had another type. They also identified 12 types of toxin in a marine alga in French Polynesia, which could be the primary source. The researchers say that the method outperforms current detection methods and in addition to helping diagnose patients, it will also help scientists study how the toxins move through the food chain from one animal to another.

More information: Detailed LC-MS/MS Analysis of Ciguatoxins Revealing Distinct Regional and Species Characteristics in Fish and Causative Alga from the Pacific, Anal. Chem., Article ASAP. DOI: 10.1021/ac200799j

Toxin profiles of representative ciguatera species caught at different locations of Japan were investigated in fish flesh by high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Identification and quantification of 16 toxins were facilitated by the use of 14 reference toxins prepared by either synthesis or isolation from natural sources and the previous LC-MS data thereof. Sodium adduct ions [M + Na]+ were used as parent and product ions. Distinct regional differences were unveiled: ciguatoxin-1B type toxins were found in snappers and groupers from Okinawa, ciguatoxin-3C type toxins were found in a spotted knifejaw, Oplegnathus punctatus, from Miyazaki located 730 km north of Okinawa, and both types of toxins were found in a red snapper, Lutjanus bohar, from Minamitorishima (Marcus) Island. Twelve toxins were identified in a dinoflagellate, Gambierdiscus toxicus, collected as the primary toxin source in French Polynesia. Occurrence of M-seco-toxins in fish and oxidized toxins in the dinoflagellate was confirmed for the first time. The present LC-MS/MS method is rapid, specific, and accurate. It not only outperforms the currently employed mouse bioassays but also enables the study of the toxin dynamics during the food chain transmission.

Provided by American Chemical Society (news : web)

Researchers discover key aspect of process that activates breast cancer genes

Michael R. Stallcup, Ph.D., professor and chair of the Keck School's Department of Biochemistry and Molecular Biology, was the senior author, and Kwang Won Jeong, Ph.D., a postdoctoral student in Stallcup's lab, was the first author of the paper, "Recognition of enhancer element-specific histone methylation by TIP60 in transcriptional activation." It was published online in the research journal Nature Structural & Molecular Biology on Nov. 13.

Researchers at the Keck School of Medicine of the University of Southern California have discovered key processes by which , the female sex hormone, activates in breast-cancer cells. Greater understanding of how this occurs is expected to eventually lead to new treatments for the disease.

The researchers found that a protein, TIP60, recognizes when a common chemical process called methylation occurs in , the material that enfolds all genes. Methylation controls how genes are folded in the complex structure of chromatin, which determines whether the genes are active or inactive. The researchers discovered that after recognizing the methylation signal, TIP60 then binds to the signal, connecting TIP60 to the chromatin and then changing the chromatin's structure, which helps to activate the gene. The methylation that TIP60 recognizes is generated by another protein, MLL1.

"It's like when you're in your car and come to a red light," said Stallcup. "The light doesn't make you stop, but it is a signal that you have to interpret and then decide to stop. In this case, the methylation modification that TIP60 recognizes is one of those signals, and then TIP60 acts on that signal."

The findings build upon previous work of Stallcup's lab. Earlier published research revealed that the methylation of chromatin and other proteins plays many important roles in controlling the activities of genes.

While the recent findings are significant, Stallcup stressed that there is much more to be discovered.

"We want to understand more about other steps in the process of gene activation," Stallcup said. "In particular, we're interested in the function of the MLL1 protein because we think it plays a key role in controlling chromatin structure and folding, which we think is critical for activation of genes by estrogen."

Stallcup also noted that estrogen regulates just a few hundred of the tens of thousands of genes in every human cell, but that the research has broader implications.

"While the process we're studying is the regulation of gene activity by estrogen, the findings have potentially global significance,,because the methylation modification of chromatin that TIP60 recognizes is found in all active and potentially active genes in human cells," Stallcup said.

Provided by University of Southern California (news : web)

Generating ethanol from lignocellulose possible, but large cost reductions still needed

Ethanol can be blended with gasoline to reduce our dependency on fossil fuels. The last 15 years has seen a massive growth of so-called first-generation processes that use enzymes and bacteria to turn the starch and sugars in corn and sugarcane into . But corn and sugarcane are also important components of the human food web, so using them for ethanol production has the potential to affect the price and availability of these basic commodities.

On the other hand, lignocellulose materials are often hard to dispose of, but they are rich in sugars that can be fermented into ethanol following appropriate processing. "Not only is cellulose the most abundant polymer on Earth, it cannot be digested by humans, so using it for fuel production does not compete directly with food supplies," says the study's lead author Jamie Stephen, who works in the Department of Wood Science at the University of British Columbia in Vancouver, Canada. The race is on to commercialize this second generation ethanol.

Stephen's work focuses on the fact that the cost of building large scale ethanol-producing facilities will likely be higher for second generation ethanol compared to first generation technologies. One reason is that sources of lignocellulose may require significant and costly pre-treatment. "Researchers and companies are going to have to concentrate on reducing the cost of pretreatment and increasing the output of the digester in order to reduce the costs of the lignocellulose-to-ethanol process," says Stephen.

Another reason costs are higher is that lignocellulose is made of multiple kinds of sugar, while consists of pure glucose. Corn starch can be reduced to glucose with low-cost amylase enzymes, while pre-treated lignocellulose requires a cocktail of cellulase enzymes. Providing these enzymes is one of the major costs of the whole process, but you currently need 12 times more cellulase than amylase protein to generate the same amount of ethanol from woody biomass. "Despite much effort and progress over the last few years, the cost of using cellulase enzymes is still significantly higher than for amylase-based processes, and will need to be reduced substantially before lignocellulose starts to become competitive with corn and sugarcane as a feedstock," says Stephen.

Finally, while the input to sugarcane- and corn starch-based systems is fairly constant, the feedstocks that go into lignocellulose systems are much more variable. Different species of tree produce wood that has different properties, and waste paper and agricultural wastes will have many different types of material in them. To get maximum , each type of biomass needs to be processed under different conditions, which introduces another challenge for anyone wanting to make ethanol from these materials.

Overall Stephen believes we have a considerable way to go before second-generation ethanol production will be ready for commercialisation. "Production requires significant cost reductions and at least the same level of financial support that was given to the first-generation systems if second-generation ethanol is going to be fully competitive by 2020," says Stephen.

Provided by Wiley (news : web)

Scientists enumerate advances, retreats in designing new membranes for renewable energy storage

Since the vanadium redox flow battery was first invented, researchers have studied refining the Nafion membrane, a DuPont polymer containing sulfur and fluoride, or replacing the with a less-expensive option. In their paper, Schwenzer and her colleagues discuss the required features of an efficient membrane, including , water transport, and ion diffusion.

"Reviewing the membrane research, which began in the mid-1980s, is an important and ambitious undertaking," said Dr. Jun Liu, who leads the Transformational Materials Science Initiative at PNNL and is a colleague of Schwenzer's. "I'm delighted with the depth and breadth of this article."

Finding or designing an efficient membrane demands a more inclusive approach than is typically taken, notes Schwenzer. Replacements or refinements to the membranes must be examined on their own and in working batteries.

"A lot of studies provide data on the membranes ex situ, outside of the battery," said Schwenzer, an inorganic chemist. "But, there are no follow-up articles showing how the materials perform inside a battery. The studies say that some properties of the membranes are good, but they don't show you the actual battery data."

The nation relies on fossil fuels to meet its residential and industrial , with coal providing about half of the electricity consumed in the United States. The emissions from coal and other fossil fuel plants cause environmental concerns. However, replacing these power sources with wind and solar farms requires megawatt-level storage capacity to buffer the intermittent generation from these renewable sources. Vanadium redox flow batteries could fit the bill, if membrane cost and maintenance issues are resolved.

"I'm hoping that our article in ChemSusChem is a guide for researchers to see what worked and what didn't," said Schwenzer. "It could help them design the materials they need to build better batteries, showing them where the opportunities lie and where current challenges exist."

The authors of this review are part of a team of materials experts at PNNL who are putting this information to use by conducting fundamental and applied research to reduce the costs and improve the efficiency of large-scale energy storage. Currently, Schwenzer and her colleagues are building larger batteries to see how changes to the and other battery components affect the overall performance.

"We are looking at the whole system and determining why it fails -- not just if it fails," said Schwenzer.

More information: B Schwenzer, J Zhang, S Kim, L Li, J Liu, and Z Yang. 2011. "Membrane Development for Vanadium Redox Flow Batteries." ChemSusChem 4(10)1388-1406. DOI: 10.1002/cssc.201100068

Provided by Pacific Northwest National Laboratory (news : web)

Zeroing in on more powerful enzymes for degrading persistent pollutants

Certain chemical components, like , PAHs, and CFCs, are toxic biosphere pollutants that are resistant to microbial degradation. Microbial catabolic enzymes are unable to effectively metabolize them. The results obtained by Professor Sylvestre and his colleagues open up new possibilities for boosting the effectiveness of these enzymes to oxidize such compounds.

Professor Sylvestre's research team has shown that it is possible to obtain more flexible mutant enzymes by replacing some of their amino acids. Moreover, they have updated a sophisticated mechanism that helps boost the enzyme's performance not only with regard to the natural substrate, but also any other substrates it can metabolize. As such, more effective new enzymes can be developed using genetic engineering.

"From a green chemistry perspective, the results of our research could allow us to apply these enzymes to biocatalysis processes to synthesize biologically active compounds (such as flavonoids) that have strong antioxidant properties," explained Professor Michel Sylvestre, also an engineering specialist.

More information: The results were published in the following works:

Mohammadi, M., Viger, J.F., Kumar, P., Barriault, D., Bolin, J. T., Sylvestre, M. 2011. "Retuning Rieske-type oxygenase to expand substrate range." J. Biol Chem. 286, 27612-27621. … 932c85d04095

Kumar, P., Mohammadi, M., Viger, J.F., Barriault, D., Gomez-Gil, L., Eltis, L.D., Bolin, J. T., and Sylvestre, M. 2011. "Structural insight into the expanded PCB-degrading abilities of a biphenyl dioxygenase obtained by directed evolution." J. Mol. Biol. 405, 531-547. … 28361001209X

Dhindwal, S., D. N. Patil, M. Mohammadi, M. Sylvestre, S. Tomar, and P. Kumar. 2011. "Biochemical studies and ligand bound structures of biphenyl dehydrogenase from Pandoraea pnomenusa strain B-356 reveal a basis for broad specificity of the enzyme." J. Biol. Chem. 286, 37011-37022. … 932c85d04095

Provided by INRS

Tuesday, November 29, 2011

Oil more easily converted into petrol thanks to a smart observational technique

NWO researcher Bert Weckhuysen and his team from Utrecht University in collaboration with the company Albemarle Catalysts, have now succeeded in imaging how well the particles do their work. As a result of this research better catalysts can now be found. This will enable the to continue producing qualitatively good fuels from the dwindling reserves of crude oil that are often of a poor quality. The research was published in the November issue of Nature Chemistry.

The catalysts used by are smart, minuscule full of pores and ‘acid sites’. The oil particles, long hydrocarbon chains, creep into the pores and are chopped into shorter chains at the acid sites. This is the so-called cracking of crude oil. These shorter hydrocarbon chains can then be combusted as petrol or diesel in a car engine.

‘Everyone had always thought that each cracking sphere had about the same activity and that active sites were spread equally over the grain. Yet the reality is very different,’ says Weckhuysen. ‘Under a fluorescence microscope we made a 3D map of the active sites in such spheres. We can detect those sites using thiophene. As soon as such a molecule is in the vicinity of the acid sites it emits green fluorescing light.’ Knowledge about these active acidic sites can be used to select the most effective catalysts. That will make it easier to convert oil into petrol. Furthermore, using this technique it can be seen when the particles become less active and therefore need replacing.

Provided by Netherlands Organisation for Scientific Research (NWO) (news : web)

Chemists reveal the force within you

"Now we're able to measure something that's never been measured before: The force that one molecule applies to another molecule across the entire surface of a living cell, and as this cell moves and goes about its normal processes," says Khalid Salaita, assistant professor of biomolecular chemistry at Emory University. "And we can visualize these forces in a time-lapsed movie."

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Salaita developed the florescent-sensor technique with chemistry graduate students Daniel Stabley and Carol Jurchenko, and undergraduate senior Stephen Marshall.

" are constantly tugging and pushing on their surroundings, and they can even communicate with one another using mechanics," Salaita says. "One way that cells use forces is evident from the characteristic architecture of tissue, like a lung or a heart. If we want to really understand cells and how they work, we have to understand cell mechanics at a molecular level. The first step is to measure the tension applied to specific receptors on the cell surface."

The researchers demonstrated their technique on the (EGFR), one of the most studied cellular signaling pathways. They mapped the exerted by EGFR during the early stages of endocytosis, when the of a cell takes in a , or binding molecule. The results showed that the cell does not passively absorb the ligand, but physically pulls it inside during the process. Their experiments provide the first direct evidence that force is exerted during .

Mapping such forces may help to diagnose and treat diseases related to cellular mechanics. , for instance, move differently from normal cells, and it is unclear whether that difference is a cause or an effect of the disease.

"It's known that if EGFR is over-active, that can lead to cancer," Salaita says. "And one of the ways that EGFR is activated is by binding its ligand and taking it in. So if we can understand how tugging on EGFR force changes the pathway, and whether it plays a role in cancer, it might be possible to design drugs that target this pulling process."

Several methods have been developed in recent years to try to study the mechanics of cellular forces, but they have major limitations.

One genetic engineering approach requires splitting open and modifying proteins of a cell. This invasive technique may change the behavior of the cell, skewing the results.

The technique developed at Emory is non-invasive, does not modify the cell, and can be done with a standard florescence microscope. A flexible polymer is chemically modified at both ends. One end gets a florescence-based turn-on sensor that will bind to a receptor on the cell surface. The other end is chemically anchored to a microscope slide and a molecule that quenches fluorescence.

"Once a force is applied to the polymer, it stretches out," Salaita explains. "And as it extends, the distance from the quencher increases and the fluorescent signal turns on and grows brighter. We can determine the force being exerted by measuring the amount of fluorescent light emitted."

The forces of any individual protein or molecule on the can be measured using the technique, at far higher spatial and temporal resolutions than was previously possible.

Many mysteries beyond the biology and chemistry of cells may be explained through measuring cellular forces. How does a cancer cell crawl when a tumor spreads? What are the forces involved in cell division and immune response? What are the mechanics that allow groups of cardiac cells to beat in unison?

"Our method can be applied to nearly any receptor, opening the door to rapidly studying chemical and mechanical interactions across the thousands of membrane-bound receptors on the surface of virtually any cell type," Salaita says. "We hope that measuring cellular forces could then become part of the standard repertoire of biochemical techniques that scientists use to study living systems."

Provided by Emory University (news : web)

Glass sponges inspire: Hybrid material made of collagen fibers and silica as possible substrate for bone tissue culture

Biomineralization is a very complicated process that is not so easy to mimic. The silicate precursors required for the synthesis of the cell walls of diatoms are in a stabilized form, which prevents their uncontrolled polymerization. Special proteins then control the polymerization to make the highly complex structures of the resulting scaffold. Researchers would also like to control biomineralization processes to repair damaged teeth or to make synthetic cartilage and tissue. In order to culture bones, scientists would like to seed osteoblasts (bone building cells) from the patient’s own body onto a substrate, where they would attach and multiply. This scaffolding would be implanted to help damaged bone, in cases of osteoporosis-induced or highly complicated fractures for example, to regenerate. Osteoblasts release collagen, calcium phosphate, and calcium carbonate as the basis for new bone material.

would be an ideal substrate, but they are not solid enough for bone repair. The researchers once again turned to nature for inspiration: in glass sponges, a collagen matrix is one component of the silica scaffolding. Would it thus be possible to strengthen a collagen structure with silica (silicon dioxide)? Although many teams have previously failed in their attempts, the team led by Tay and Chen has now been successful.

They used collagen fibers as both a “mold” and a catalyst for the polymerization of the liquid phase of a silica precursor compound to make solid silica. The silica precursor is stabilized with choline to prevent an uncontrolled polymerization. This leaves enough time for the liquid precursor to fully infiltrate the space between the microfibrils of the collagen fibers before it polymerizes to form silica—one secret to the success of this new approach. After the polymerization the solid reflects the architecture determined by the collagen fibers. After drying, the original sponge-like, porous structure of the collagen fibers is maintained. In contrast to pure collagen, the scaffold of the hybrid compound is stable and could, the researchers hope, be used to repair bones.

More information: Franklin R. Tay, Infiltration of Silica Inside Fibrillar Collagen, Angewandte Chemie International Edition, … ie.201105114

Provided by Wiley (news : web)

Iodate refuses to intimidate

Whether they are creating a catalyst for petroleum-free fuel or designing better drug therapies, scientists need to control ions' actions in . To control the ions, they must accurately characterize their behavior. This study answers a fundamental question about the behavior of large, negatively charged ions with multiple atoms, called polyoxyanions.

"To our knowledge, this is the first time anyone has microscopic insight into the solvation of a polyoxyanion," said Dr. Chris Mundy, a physical chemist at PNNL who co-authored the study.

When examining the behavior of large ions in water, the is that large anions, negatively charged ions, such as iodate (IO3-) should disrupt the ordered structure of water. For example, (I-) creates cavities within the water and is eventually expelled to the surface.

However, studies assigned iodate as strongly hydrating, meaning it resided in the liquid, not at the surface.

"The puzzle was why iodate did not behave like its slightly smaller cousin, iodide," said Mundy.

The research team took on that puzzle by integrating and experimental studies with iodate. The simulations determined that the central iodine atom is positively charged, even though the ion has a negative charge. The simulations were density-functional theory-based run on a powerful computing system known as NWIce at EMSL.

The iodine's cationic behavior strongly attracts the negative on three nearby . By tightly surrounding itself with water, the iodate is able to blend into the water.

"I would usually expect every water molecule to point a hydrogen at the anion," said Dr. Marcel Baer, a Linus Pauling Postdoctoral Fellow at PNNL who worked on the study. "The structure was surprising to me . . .very unexpected."

The simulations were confirmed by X-ray absorption fine structure spectroscopy studies. Using the light source at the Advanced Photon Source, the team was able to examine the structure of the ion in water.

"This one is not the same as the pure hydration that would normally be seen with a cation. It has its own structure," said Dr. Van-Thai Pham, a postdoctoral researcher at PNNL who worked on the spectroscopy investigations at the light source.

The research team's results appear in The Journal of Physical Chemistry Letters.

The researchers are further delving into the mysteries of iodate. The team is looking into the water surface to see if iodate is absorbed or the water shell that forms rejects the ion at the surface. In addition, team members are studying how other ions behave in water. They are focusing on ions based on positively charged cesium, bromide, and rubidium. Understanding these and others has implications from alternative energy sources to new drug therapies.

More information: MD Baer, et al. 2011. "Is Iodate a Strongly Hydrated Cation?" The Journal of Physical Chemistry Letters 2, 2650-2654. DOI: 10.1021/jz2011435.

Provided by Pacific Northwest National Laboratory (news : web)

Monday, November 28, 2011

Patent application for innovative film - possible Indium Tin Oxide replacement

On Nov. 5, Iroh filed a provisional patent application with the U.S. Patent Office for a polymer-based film with remarkable properties. The film is highly transparent and electrically conductive. It has potential uses in energy, including applications in solar and . It is economical, easily processed, durable, flexible, and heat resistant.

"Because of its properties, this film is very flexible," Iroh said. "I can envision a very thin solar panel that can be unrolled and applied, perhaps to an automobile, while the sun is shining, then peeled off and stored."

More importantly, Iroh's innovative film has the potential to replace a substance known as ITO, an abbreviation for . While the acronym may be unfamiliar to most consumers, ITO's uses are not. ITO is behind most touch-screen devices like and video kiosks. It appears in flat panel displays, electronic inks, and (LEDs).

ITO is also expensive and rare. It is fragile, lacks flexibility, and it is requires complicated processes to apply. All the major sources of Indium lie outside the United States, lending a strategic value to a suitable replacement for ITO.

Development of the new film grew out of Iroh's work on coatings.

"My initial focus was in composites, particularly laminated composites," he said. "It was for that work that I received my first patents."

After earning his Ph.D. from the University of Connecticut in 1990 and a Post-doctoral stint at Temple University, Iroh accepted a position at the University of Cincinnati as an assistant professor on September 1, 1991. His research attracted the attention of the Office of Naval Research, which asked him to look into coatings to protect metal. Iroh's projects earned acclaim from the Office of Naval Research, and he was named an ONR Young Investigator for 1995-1999. This honor was followed by others. Iroh was selected as the Sigma Xi Young Investigator at the University of Cincinnati for 2001, and was named a Resident Senior Research Associate at the Air Force Research Laboratory for 2002-2003. In 2004 he was elected as a Fellow of the Society for the Advancement of Materials and Process Engineering, SAMPE.

For the naval work, Iroh adapted a laminating process to apply coatings to steel.

"I was using what was then a new class of polymer, intrinsically conducting polymer, and applying it for corrosion prevention measures," he said.

Over the years, Iroh has tackled substantial problems related to coating materials. For example, adding trace amounts of various substances can improve corrosion prevention, but these "dopants" can be lost due to weather, defeating the purpose of the coating. Other coatings are very effective, but must be cured at high temperatures.

"We have found methods to reduce curing temperatures by more than 100 degrees Celsius," Iroh said. "That is very significant."

Effective coatings must meet a wide range of requirements, Iroh said. Cost is a factor, as is ease of application, environmental safety, ability to adhere and impact resistance.

The impact resistance of nanocomposite coatings has opened a fruitful partnership between Iroh's laboratory and Jackson State University, a historically black university in Mississippi. Funded by the Office of Naval Research, Jackson State students are working with Iroh's lab on low temperature systems for high-impact epoxy coatings.

"I would hope to see some of these students return here one day as graduate student," he said.

As Iroh gained more insight into the function of various substances as coatings, it occurred to him that these coating had useful properties, even if they were not coating something.

"A coating is essentially a film. What properties does this film possess?" Iroh said.

It was the question that led to the development of the highly transparent, electrically conductive, polymer-based nanocomposite film.

"This breakthrough will give us a unique place in the broader field of composites and energy research," he said. "This is an exciting development, and I am glad that my research group is very well positioned to continue to make a significant impact in this area."

Provided by University of Cincinnati (news : web)

Research team achieves critical step to opening elusive class of compounds to drug discovery

Taxol®, the trade name for a chemical called paclitaxel first discovered in 1967 in the bark of a yew tree, is a highly successful drug used to treat ovarian, breast, lung, liver, and other cancer types. No less than seven different research groups have designed several ways to produce Taxol® synthetically, beginning in the 1990s with a team led by K.C. Nicolaou, chair of the Scripps Research Department of Chemistry.

While each synthesis was a significant accomplishment, each has also been exceedingly complex and inefficient. Using all these methods collectively, researchers have produced less than 30 milligrams of synthetic Taxol®. Producing other chemicals from the same promising taxanes chemical group is nearly as challenging, vastly limiting access to them for research.

Building Ferraris

Finding an efficient way to produce Taxol® in sizable quantity in the laboratory remains one of the most sought-after and elusive goals in organic chemistry. If accomplished, it would open the door to producing countless other taxanes that are not accessible from nature. Past methods were devised using conventional schemes where researchers plot a linear path of increasingly complex molecules leading to a target compound. Creating each increasingly complex molecule along that line is an inefficient process that often requires numerous extra steps to prevent unwanted reactions or to correct other chemical complications. "It's like trying to convert a Toyota Corolla into a Ferrari instead of just building a Ferrari," said Baran.

To build the Ferrari, Baran and his team are taking a different route. In 2009, the researchers showed that by using an unconventional scheme they could produce a simpler relative of Taxol® called eudesmane. They analyzed this target and then created what Baran calls a retrosynthesis pyramid. This is a diagram with the target compound at the top and lower levels filled with molecules that could theoretically be modified to reach the level above them. Such a pyramid reveals not a set linear path, but a variety of path options open to chemical exploration.

With taxanes and related there are two main phases in production, the cyclase phase and oxidase phase. Working up the bottom half of the pyramid involves mostly well-understood chemistry. During this cyclase phase, researchers construct a chemical scaffolding that Baran likens to a Christmas tree to which ornaments must then be attached. The ornaments are primarily reactive oxygen molecules and this "decoration," or oxidation, phase is the most challenging.

The eudesmane synthesis was something like decorating the Charlie Brown Christmas tree, while a completed Taxol® production could be compared to the lighting of the famous multi-story Rockefeller Center tree.

In the new paper, Baran's group reports erecting that Rockefeller tree and adding the first few ornaments -- a molecule called taxadiene. "It's a Herculean task," said Baran of Taxol® synthesis, "What we're doing here is merely part one."

A conventional taxadiene synthesis is inefficient and involves 26 steps to produce. The Baran group's method involves just 10 steps to produce many times what has been previously synthesized -- more than sufficient for planned research to find a way to efficiently produce Taxol®.

Innovation Leads to Access

The taxadiene synthesis is more than just a midway stop on the way to Taxol®. The researchers chose this molecule intentionally because, like a Christmas tree that can be decorated in any number of ways, this molecule can be modified to create a wide range of taxanes of varying complexities.

This is key, because at its heart the research isn't only about finding a better way to produce Taxol®, even though the group is working toward that goal. The current commercial Taxol® production method, which involves culturing cells from the yew tree, is more economical than any new synthesis is likely to be.

Instead, Baran and his team are aiming to understand the processes used in nature to produce the compound, which are many times more efficient than those used by scientists to date. "It's my opinion that when there's a huge discrepancy between the efficiency of nature and humans, in the space between, there's innovation."

More specifically, Baran believes that while developing an efficient synthesis for Taxol®, they will gain a fundamentally improved understanding of the chemistry involved and develop more widely applicable techniques. Such innovation could allow production of a whole range of taxanes currently inaccessible for drug discovery research either because the quantities researchers can produce are vanishingly small, or because they can't produce them at all. Control of the taxane oxidation process therefore offers the potential for discovering new and important drugs, perhaps even one or more that is better at fighting specific cancers than Taxol®.

Establishing the remaining steps between taxadiene and ® or other more complex taxanes remains a challenging task that Baran estimates will take years. "Nature has a choreography in the way she decorates the tree," he said. "It's a precise dance she has worked out over millennia. We have to figure out a way to bring that efficiency to the laboratory setting."

The project, led by Scripps Research chemist Phil Baran, is described November 6, 2011 in an advance, online issue of the journal Nature Chemistry.

Provided by The Scripps Research Institute (news : web)

USC team develops promising polymer for solar cells

One way to do this, researchers believe, is to create a based material that could be used instead of . Such material would cost less to produce and have sufficient bendiness that it could be printed onto bendable surfaces in much the same way newspapers are mass printed, i.e. via giant rollers. Up to now though, figuring out how to create such a polymer that is as efficient at converting sunlight into energy as silicon-based cells, hasn’t really worked out.

Now though, a team working out of USC, headed by Alan Heeger, who along with Guillermo Bazan won the Nobel Prize in Physics back in 2000 for groundbreaking work they did on polymer cells, believe they have made another breakthrough. In their paper, published in Nature Materials, they say they’ve figured out a way to use an organic material with a low molecular weight (small molecule) to produce a solar cell that is every bit as efficient as current silicon technology.

The small molecule technology came about as the result of work done by Bazan, who used theory and lots of trial and error to produce just the right material; one that could, unlike many others that had been tried, be formed into a layer that could be applied to other . Heeger then took the lead in applying the new material in a solar cell. The end result the team says, is a solar cell capable of matching the 6.7% energy efficiency of silicon cells. And not only that, they believe with some tweaking, they can get it to 9%.

Unfortunately, there is a dark cloud looming ahead, and that is because the team isn’t sure just yet if the new material will work as designed once it’s ramped up to commercial size. In the past, when polymers have been sized up, their efficiencies went down.

More information: Solution-processed small-molecule solar cells with 6.7% efficiency, Nature Materials (2011) doi:10.1038/nmat3160

Organic photovoltaic devices that can be fabricated by simple processing techniques are under intense investigation in academic and industrial laboratories because of their potential to enable mass production of flexible and cost-effective devices1, 2. Most of the attention has been focused on solution-processed polymer bulk-heterojunction (BHJ) solar cells3, 4, 5, 6, 7. A combination of polymer design, morphology control, structural insight and device engineering has led to power conversion efficiencies (PCEs) reaching the 6–8% range for conjugated polymer/fullerene blends8, 9. Solution-processed small-molecule BHJ (SM BHJ) solar cells have received less attention, and their efficiencies have remained below those of their polymeric counterparts10. Here, we report efficient solution-processed SM BHJ solar cells based on a new molecular donor, DTS(PTTh2)2. A record PCE of 6.7% under AM 1.5?G irradiation (100?mW?cm-2) is achieved for small-molecule BHJ devices from DTS(PTTh2)2:PC70BM (donor to acceptor ratio of 7:3). This high efficiency was obtained by using remarkably small percentages of solvent additive (0.25%?v/v of 1,8-diiodooctane, DIO) during the film-forming process, which leads to reduced domain sizes in the BHJ layer. These results provide important progress for solution-processed organic photovoltaics and demonstrate that solar cells fabricated from small donor molecules can compete with their polymeric counterparts.

? 2011

Team develops speedy software designed to improve drug development

Similarly, when a newly created drug doesn’t bind well to its intended target, the drug won’t work. Scientists are then forced to go back to the lab, often with very little indication about why the binding was weak. The next step is to choose a different “combination” and hope for better results. Georgia Tech researchers have now generated a computer model that could help change that blind process.

Symmetry-adapted perturbation theory (SAPT) allows scientists to study interactions between molecules, such as those between a drug and its target. In the past, computer algorithms that study these noncovalent interactions have been very slow, limiting the types of molecules that can be studied using accurate quantum mechanical methods. A research team headed by Georgia Tech Professor of Chemistry David Sherrill has developed a computer program that can study larger molecules (more than 200 atoms) faster than any other program in existence. 

“Our fast energy component analysis program is designed to improve our knowledge about why certain molecules are attracted to one another,“ explained Sherrill, who also has a joint appointment in the School of Computational Science and Engineering. “It can also show us how interactions between molecules can be tuned by chemical modifications, such as replacing a hydrogen atom with a fluorine atom.  Such knowledge is key to advancing rational drug design.”

Georgia tech develops speedy software designed to improve drug development

Computer Program Quickly Analyzes Molecular Interactions II

The algorithms can also be used to improve the understanding of crystal structures and energetics, as well as the 3D arrangement of biological macromolecules. Sherrill’s team used the to study the interactions between DNA and proflavine; these interactions are typical of those found between DNA and several anti-cancer drugs. The findings are published this month in the Journal of Chemical Physics.

Rather than selling the software, the Georgia Tech researchers have decided to distribute their code free of charge as part of the open-source computer program PSI4, developed jointly by researchers at Georgia Tech, Virginia Tech, the University of Georgia and Oak Ridge National Laboratory.  It is expected to be available in early 2012.

“By giving away our source code, we hope it will be adopted rapidly by researchers in pharmaceuticals, organic electronics and catalysis, giving them the tools they need to design better products,” said Sherrill.

Sherrill’s team next plans to use the software to study the noncovalent interactions involving indinavir, which is used to treat HIV patients.

Provided by Georgia Institute of Technology (news : web)

Sunday, November 27, 2011

Sensible use of biomass: A chemical industry based on renew

In an essay presented in the journal , Esben Taarning and co-workers from the company Haldor Topsoe and the Lindoe Offshore Center (Denmark) describe how a sensible transition from to a chemical industry based on biomass might look.

To date, most of the biomass used by industry has been burned to generate energy. According to the authors, in the long term this is not the optimal use. “It is also not the most sensible solution to convert biomass into fuels,” says Taarning. “In the first place, the amount of biomass available does not meet the demand for fuels; in the second, the chemical characteristics of fuels and biomass are too different, so the processes would be too complex and uneconomical.” Means of transportation should be gradually switched to batteries or fuel cells.” Says Taarning: “In contrast, it really makes sense to use biomass as the for chemical industry. The available biomass should suffice to replace the fossil feedstocks used in the production of chemicals. The chemical characteristics of biomass and many bulk chemicals are also very similar, so the processes should be more economical than those for the conversion into fuels.”

When we do this, however, we need to diverge from the established value chains: instead of using brute force to convert these raw materials into specific platform chemicals that were originally selected because of their easy accessibility when starting from fossil resources, it would be better to use the interesting chemical characteristics already available in the biomass resources themselves and to optimize the use of favorable catalytic reaction pathways. “Through the clever selection of target chemicals it is possible to significantly increase the value added,” says Taarning. Because the development costs will be high and the first processes inefficient, it makes sense to initially concentrate on high-value products, thereby allowing for faster widespread adoption.

Also, many primary products and by-products of our current biofuel industry could be interesting platform chemicals in themselves: for example, ethanol as a starting material for the production of acetic acid, ethylene, and ethylene glycol, or glycerol for conversion into acrylic acid, a polymer precursor.

“The shift from a fossil-based chemical industry to one based on biomass poses many challenges,” says Taarning, “but the possibilities are also great: to develop a more sustainable chemical industry utilizing a more versatile feedstock supply and producing products with superior properties.”

More information: Esben Taarning, Beyond Petrochemicals: The Renewable Chemicals Industry, Angewandte Chemie International Edition 2011, 50, No. 45, 10502–10509, Permalink to the article: … ie.201102117

Provided by Wiley (news : web)

Tear drops may rival blood drops in testing blood sugar in diabetes

Mark Meyerhoff and colleagues explain that about 5 percent of the world's population (and about 26 million people in the U.S. alone) have diabetes. The disease is a fast-growing public health problem because of a sharp global increase in obesity, which makes people susceptible to developing type 2 diabetes. People with diabetes must monitor their blood levels several times a day to make sure they are within a safe range. Current handheld glucose meters require a drop of blood, which patients draw by pricking their fingers with a small pin or lancet. However, some patients regard that pinprick as painful enough to discourage regular testing. That's why Meyerhoff's team is working to develop a new, pain-free device that can use tear glucose levels as an accurate reflection of .

Tests of their approach in laboratory rabbits, used as surrogates for humans in such experiments, showed that levels of glucose in tears track the amounts of glucose in the blood. "Thus, it may be possible to measure tear multiple times per day to monitor blood glucose changes without the potential pain from the repeated invasive blood drawing method," say the researchers.

More information: Measurement of Tear Glucose Levels with Amperometric Glucose Biosensor/Capillary Tube Configuration, Anal. Chem., 2011, 83 (21), pp 8341–8346. DOI: 10.1021/ac201700c

An amperometric needle-type electrochemical glucose sensor intended for tear glucose measurements is described and employed in conjunction with a 0.84 mm i.d. capillary tube to collect microliter volumes of tear fluid. The sensor is based on immobilizing glucose oxidase on a 0.25 mm o.d. platinum/iridium (Pt/Ir) wire and anodically detecting the liberated hydrogen peroxide from the enzymatic reaction. Inner layers of Nafion and an electropolymerized film of 1,3-diaminobenzene/resorcinol greatly enhance the selectivity for glucose over potential interferences in tear fluid, including ascorbic acid and uric acid. Further, the new sensor is optimized to achieve very low detection limits of 1.5 ± 0.4 µM of glucose (S/N = 3) that is required to monitor glucose levels in tear fluid with a glucose sensitivity of 0.032 ± 0.02 nA/µM (n = 6). Only 4–5 µL of tear fluid in the capillary tube is required when the needle sensor is inserted into the capillary. The glucose sensor was employed to measure tear glucose levels in anesthetized rabbits over an 8 h period while also measuring the blood glucose values. A strong correlation between tear and blood glucose levels was found, suggesting that measurement of tear glucose is a potential noninvasive substitute for blood glucose measurements, and the new sensor configuration could aid in conducting further research in this direction.

Provided by American Chemical Society (news : web)

Researchers unravel biochemical factor important in tumor metastasis

According to study corresponding author Shengyu Yang, Ph.D., of Moffitt's Comprehensive Melanoma Research Center and the Department of , elevated Transforming Growth Factor beta in the may be responsible for fascin over-expression, which in turn can promote metastasis in some metastatic tumors.

TGF beta is a versatile cytokine involved in many physiological and pathological processes in adults and in the developing embryo, including cell growth, cell differentiation, cell death (apoptosis) and cellular homeostasis. TGF beta is best known as a tumor suppressor, exerting growth inhibitory roles in normal tissue and early stage tumors. However, many are able to overcome the growth inhibition and secreted elevated levels of TGF beta to promote tumor metastasis. How TGF beta promotes metastasis is not completely understood. The authors suggested that fascin may be the key to understand the pro-metastasis function of TGF beta, as fascin knockdown almost completely abolished TGF beta induced and invasion.

The researchers explained that fascin levels are low or not detected in normal tissues, but are highly elevated in malignant tumors. Also, high fascin expression is associated with poor prognosis. It has been clear for some time, they noted, that there is a causal role for fascin over-expression in tumor cell dissemination. However, the underlying mechanism for the elevation of fascin levels has not been clarified. Their analysis using cell culture- based assay and patient microarray data mining strongly suggests that elevated TGF in tumors lead to fascin overexpression, which in turn promotes metastasis.

"Our data suggests that fascin is an immediate TGF beta target gene essential for its pro-invasion activity in cancer metastasis," explained Yang.

While there have been many studies on the role of fascin in tumor cell migration and metastasis, the current study is first to report that TGF beta elevates fascin protein expression to promote invasion, particularly in tumor cells of spindle-shaped – the kind of morphology associated with high tumor invasiveness and more metastatic disease.

"The finding that TGF beta only induces fascin over-expression in highly metastatic tumor cells is especially interesting," said Yang. "Therapies targeting fascin may block TGF beta mediated metastasis without interfering with the role of TGF beta in normal tissues."

Provided by H. Lee Moffitt Cancer Center & Research Institute

Porous crystals for natural gas storage

A Northwestern University research team has developed a that can save scientists and engineers valuable time in the discovery process. The new algorithm automatically generates and tests hypothetical metal-organic frameworks (MOFs), rapidly zeroing in on the most promising structures. These MOFs then can be synthesized and tested in the lab.

Using their method, the quickly identified more than 300 different MOFs that are predicted to be better than any known material for methane (natural gas) storage. The researchers then synthesized one of the promising materials and found it beat the U.S. Department of Energy (DOE) natural gas storage target by 10 percent.

There already are 13 million vehicles on the road worldwide today that run on natural gas -- including many buses in the U.S. -- and this number is expected to increase sharply due to recent discoveries of natural gas reserves.

In addition to gas storage and vehicles that burn cleaner fuel, MOFs may lead to better drug-delivery, , carbon capture materials and catalysts. MOF candidates for these applications could be analyzed efficiently using the Northwestern method.

"When our understanding of materials synthesis approaches the point where we are able to make almost any material, the question arises: Which materials should we synthesize?" said Randall Q. Snurr, professor of chemical and in the McCormick School of Engineering and Applied Science. Snurr led the research. "This paper presents a powerful method for answering this question for metal-organic frameworks, a new class of highly versatile materials."

The study will be published Nov. 6 by the journal Nature Chemistry. It also will appear as the cover story in the February print issue of the journal.

Christopher E. Wilmer, a graduate student in Snurr's lab and first author of the paper, developed the new algorithm; Omar K. Farha, research associate professor of chemistry in the Weinberg College of Arts and Sciences, and Joseph T. Hupp, professor of chemistry, led the synthesis efforts.

"Currently, researchers choose to create new materials based on their imagining how the atomic structures might look," Wilmer said. "The algorithm greatly accelerates this process by carrying out such 'thought experiments' on supercomputers."

The researchers were able to determine which of the millions of possible MOFs from a given library of 102 chemical building block components were the most promising candidates for natural-gas storage. In just 72 hours, the researchers generated more than 137,000 hypothetical MOF structures. This number is much larger than the total number of MOFs reported to date by all researchers combined (approximately 10,000 MOFs). The Northwestern team then winnowed that number down to the 300 most promising candidates for high-pressure, room-temperature methane storage.

In synthesizing the storage MOF that beat the DOE storage by 10 percent, the research team showed experimentally that the material's actual performance agreed with the predicted properties.

The new algorithm combines the chemical "intuition" that chemists use to imagine novel MOFs with sophisticated molecular simulations to evaluate MOFs for their efficacy in different applications. The algorithm could help remove the bottleneck in the discovery process, the researchers said.

Provided by Northwestern University (news : web)

Researchers moving closer to a soluble solution to Haber-Bocsh process

As all those who have taken very many chemistry courses know, the Haber-Bosch process involves heating a potassium-doped catalyst under high pressure, then mixing it over with hydrogen gas to generate the end product, .

What Holland and his team are trying to do is recreate the same process using a different catalyst. Instead of the regular iron catalysts used in current processes, they would like to use a soluble iron catalyst, which most agree would allow for the process to work under room temperatures. Unfortunately, work by others in trying the same thing has thus far resulted in less than dramatic results, i.e. not enough ammonia was produced.

This new research however looks more promising. What the team has done so far is develop a new iron material that will react with nitrogen gas when exposed to potassium which generates a material that has two nitrides which contain a mixed iron nitride core - which will react with hydrogen gas to create a reasonably large amount of ammonia.

While this doesn’t exactly solve the puzzle of how to get the H-B process to work at room temperature and at normal pressure (because the iron is consumed, thus it’s not truly catalytic) it is a step in the right direction, and the team is optimistic that because of knowledge gained in their experiments, they will be able to build a complex that is truly catalytic, which will then lead to a real solution to the underlying problem.

More information: N2 Reduction and Hydrogenation to Ammonia by a Molecular Iron-Potassium Complex, Science 11 November 2011:
Vol. 334 no. 6057 pp. 780-783. DOI: 10.1126/science.1211906

The most common catalyst in the Haber-Bosch process for the hydrogenation of dinitrogen (N2) to ammonia (NH3) is an iron surface promoted with potassium cations (K+), but soluble iron complexes have neither reduced the N-N bond of N2 to nitride (N3–) nor produced large amounts of NH3 from N2. We report a molecular iron complex that reacts with N2 and a potassium reductant to give a complex with two nitrides, which are bound to iron and potassium cations. The product has a Fe3N2 core, implying that three iron atoms cooperate to break the N-N triple bond through a six-electron reduction. The nitride complex reacts with acid and with H2 to give substantial yields of N2-derived ammonia. These reactions, although not yet catalytic, give structural and spectroscopic insight into N2 cleavage and N-H bond-forming reactions of iron.

? 2011

Saturday, November 26, 2011

Using light, researchers convert 2-D patterns into 3-D objects

“This is a novel application of existing , and has potential for rapid, high-volume manufacturing processes or packaging applications,” says Dr. Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper describing the research.

The process is remarkably simple. Researchers take a pre-stressed plastic sheet and run it through a conventional inkjet printer to print bold black lines on the material. The material is then cut into a desired pattern and placed under an infrared , such as a heat lamp.

The bold black lines absorb more energy than the rest of the material, causing the plastic to contract – creating a hinge that folds the sheets into 3-D shapes. This technique can be used to create a variety of objects, such as cubes or pyramids, without ever having to physically touch the material. The technique is compatible with commercial printing techniques, such as screen printing, roll-to-roll printing, and inkjet printing, that are inexpensive and high-throughput but inherently 2-D.

This video is not supported by your browser at this time.

Researchers from North Carolina State University have developed a simple way to convert two-dimensional patterns into three-dimensional (3-D) objects using only light. Credit: Ying Liu, North Carolina State University

By varying the width of the black lines, or hinges, researchers are able to change how far each hinge folds. For example, they can create a hinge that folds 90 degrees for a cube, or a hinge that folds 120 degrees for a pyramid. The wider the hinge, the further it folds. Wider hinges also fold faster, because there is more surface area to absorb energy.

“You can also pattern the lines on either side of the material,” Dickey says, “which causes the hinges to fold in different directions. This allows you to create more complex structures.”

The researchers developed a computer-based model to explain how the process works. There were two key findings. First, the surface temperature of the hinge must exceed the glass transition temperature of the material, which is the point at which the material begins to soften. Second, the heat has to be localized to the hinge in order to have fast and effective folding. If all of the material is heated to the glass transition temperature, no folding will occur.

“This finding stems from work we were doing on shape memory polymers, in part to satisfy our own curiosity. As it turns out, it works incredibly well,” Dickey says.

More information: The paper, “Self-folding of polymer sheets using local light absorption,” was published Nov. 10 in the journal Soft Matter, and was co-authored by Dickey; NC State Celanese Professor of Chemical and Biomolecular Engineering Jan Genzer; NC State Ph.D. student Ying Liu; and NC State undergraduate Julie Boyles. The work was supported, in part, by the U.S. Department of Energy.

This paper demonstrates experimentally and models computationally a novel and simple approach for self-folding of thin sheets of polymer using unfocused light. The sheets are made of optically transparent, pre-strained polystyrene (also known as Shrinky-Dinks) that shrink in-plane if heated uniformly. Black ink patterned on either side of the polymer sheet provides localized absorption of light, which heats the underlying polymer to temperatures above its glass transition. At these temperatures, the predefined inked regions (i.e., hinges) relax and shrink, and thereby cause the planar sheet to fold into a three-dimensional object. Self-folding is therefore achieved in a simple manner without the use of multiple fabrication steps and converts a uniform external stimulus (i.e., unfocused light) on an otherwise compositionally homogenous substrate into a hinging response. Modeling captures effectively the experimental folding trends as a function of the hinge width and support temperature and suggests that the hinged region must exceed the glass transition temperature of the sheet for folding to occur.

Provided by North Carolina State University (news : web)

UC chemistry research looks to turn food waste into fuel

The project, “Biodiesel from ,” focuses on the potential to produce biodiesel from extracted from garbage. With the depletion of oil reserves, research into alternative fuels has exploded, especially in the area of renewable resources such as garbage and food waste. One particular resource, brown grease from food waste, has yet to realize its full potential, but thanks to the efforts of University of Cincinnati chemistry researchers, the project is finding ways to optimize this resource.

One of the goals of the project was to determine the amount of usable oil that can be obtained from food waste. To do this, the researchers collected food waste—by hand— from an HCMC University of Science student canteen as well as a private residence. Samples of the food waste were then either sun-dried or dried in an oven—a process Nubel describes as “extremely dirty and smelly”—and then ground up and loaded into a homemade extraction thimble bag so that oils contained in the food could be extracted through a Soxhlet extraction.

It was during the extraction process that Nubel made an important discovery. “During this step I determined a much more efficient way of pulling remnants of oil from the bag by using the suction formed from the extractor.”

McCallister, who also helped with the food waste collection, sample preparation and oil extraction, adds that after the extraction, “we converted the oil into biofuel through an acid-based reaction.”

Part of the conversion process requires that the extracted oil be degummed to further purify it. “During the degumming process we realized that layer separation is best completed through centrifuge rather than other conventional methods because it’s both higher yielding and much quicker—by about 24 hours,” says Nubel.

From there, the oil was converted to biodiesel fuel by using a solvent, which required the researchers to determine the correct amount of solvent to add per time and heat in order to yield the highest amount of fuel.

Despite the complexity of the process—and the sometimes unseemly conditions—the results were worth the effort. “This job may have easily qualified for Mike Rowe’s show, ‘Dirty Jobs,’ but the experiment was a success and the results are awaiting publication,” says Nubel.

Herrmann also worked on the project, though in a slightly different area. He worked on taking vegetation found in Vietnam and extracting compounds from them. In a process similar to the Soxhlet extraction, Herrmann used column chromatography, which meant he also had to grind up the plants so that compounds could be extracted. “My job was to run these columns and attempt to purify one compound from thousands. We did manage to separate one compound from the plant we worked on and it was the first time that the compound had been extracted from that plant,” he says.

Not only was the research project a success, but so were the researchers themselves. Pinhas says, “What I was told in Vietnam is that the group of students from UC was the best group of students that ever participated in this program with chemists in Vietnam.”

Provided by University of Cincinnati (news : web)

New technology improves both energy capacity and charge rate in rechargeable batteries

A team of engineers has created an electrode for batteries -- such as those found in cellphones and iPods -- that allows the batteries to hold a charge up to 10 times greater than current technology. Batteries with the new electrode also can charge 10 times faster than current batteries.

The researchers combined two chemical engineering approaches to address two major battery limitations -- and charge rate -- in one fell swoop. In addition to better batteries for cellphones and iPods, the technology could pave the way for more efficient, smaller batteries for .

The technology could be seen in the marketplace in the next three to five years, the researchers said.

A paper describing the research is published by the journal Advanced .

"We have found a way to extend a new lithium-ion battery's charge life by 10 times," said Harold H. Kung, lead author of the paper. "Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today."

Kung is professor of chemical and in the McCormick School of Engineering and Applied Science. He also is a Dorothy Ann and Clarence L. Ver Steeg Distinguished Research Fellow.

Lithium-ion batteries charge through a chemical reaction in which lithium ions are sent between two ends of the battery, the and the cathode. As energy in the battery is used, the lithium ions travel from the anode, through the electrolyte, and to the cathode; as the battery is recharged, they travel in the reverse direction.

With current technology, the performance of a lithium-ion battery is limited in two ways. Its energy capacity -- how long a battery can maintain its charge -- is limited by the charge density, or how many lithium ions can be packed into the anode or cathode. Meanwhile, a battery's charge rate -- the speed at which it recharges -- is limited by another factor: the speed at which the lithium ions can make their way from the electrolyte into the anode.

In current rechargeable batteries, the anode -- made of layer upon layer of carbon-based graphene sheets -- can only accommodate one lithium atom for every six carbon atoms. To increase energy capacity, scientists have previously experimented with replacing the carbon with silicon, as silicon can accommodate much more lithium: four lithium atoms for every silicon atom. However, silicon expands and contracts dramatically in the charging process, causing fragmentation and losing its charge capacity rapidly.

Currently, the speed of a battery's charge rate is hindered by the shape of the graphene sheets: they are extremely thin -- just one carbon atom thick -- but by comparison, very long. During the charging process, a lithium ion must travel all the way to the outer edges of the graphene sheet before entering and coming to rest between the sheets. And because it takes so long for lithium to travel to the middle of the graphene sheet, a sort of ionic traffic jam occurs around the edges of the material.

Now, Kung's research team has combined two techniques to combat both these problems. First, to stabilize the silicon in order to maintain maximum charge capacity, they sandwiched clusters of silicon between the graphene sheets. This allowed for a greater number of lithium atoms in the while utilizing the flexibility of graphene sheets to accommodate the volume changes of silicon during use.

"Now we almost have the best of both worlds," Kung said. "We have much higher energy density because of the silicon, and the sandwiching reduces the capacity loss caused by the silicon expanding and contracting. Even if the silicon clusters break up, the silicon won't be lost."

Kung's team also used a chemical oxidation process to create miniscule holes (10 to 20 nanometers) in the graphene sheets -- termed "in-plane defects" -- so the lithium ions would have a "shortcut" into the anode and be stored there by reaction with . This reduced the time it takes the battery to recharge by up to 10 times.

This research was all focused on the anode; next, the researchers will begin studying changes in the that could further increase effectiveness of the batteries. They also will look into developing an electrolyte system that will allow the to automatically and reversibly shut off at high temperatures -- a safety mechanism that could prove vital in electric car applications.

More information: The paper is titled "In-Plane Vacancy-Enabled High-Power Si-Graphene Composite Electrode for Lithium-Ion Batteries."

Provided by Northwestern University (news : web)

Converting waste heat into electricity

More than half of today's energy consumption is squandered in useless waste heat, such as the heat from refrigerators and all sorts of gadgets and the heat from factories and power plants. The energy losses are even greater in cars. Automobile motors only manage to utilise 30 per cent of the energy they generate. The rest of it is lost. Part of the heat loss ends up as warm brakes and a hot exhaust pipe.

Scientists at the Centre for Materials Science and Nanotechnology at the University of Oslo in Norway (UiO) are now collaborating with SINTEF (the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology) to develop a new environmentally friendly technology called thermoelectricity, which can convert waste heat into electricity. To put it briefly, the technology involves making use of temperature differences.

Today: Toxic and expensive

Thermoelectric materials are put to many uses in space flight. When a space probe travels far enough away from the sun, its solar cells cease to work. Batteries have much too short a lifetime. Nuclear power cannot be used. However, a lump of Plutonium will do the trick.

With a temperature of a thousand degrees, it is hot. Outer space is cold. Thanks to the temperature difference, the space probe gets enough electricity.

Plutonium is a good solution for space probes that will not return to earth, but it is not a practical solution for cars and other earthly objects.

Thermoelectric materials are also currently used in the type of cooler bags that keep things cold without making use of their own cooling elements. These cooler bags are full of the elements Lead and Tellurium. Both of these substances are also toxic.

"We want to replace them with inexpensive and readily available substances. Moreover, there is not enough Tellurium to equip all of the cars in the world," says Ole Martin Lovvik, who is both an associate professor in the Department of Physics at the University of Oslo and a senior scientist at SINTEF.

Tomorrow: Environmentally friendly and inexpensive

With the current technology, it is possible to recover scarcely ten per cent of the lost energy. Together with the team of scientists led by Professor Johan Tafto, Lovvik is now searching for pollution-free, inexpensive materials that can recover fifteen per cent of all energy losses. That is an improvement of fully fifty per cent.

"I think we will manage to solve this problem with nanotechnology. The technology is simple and flexible and is almost too good to be true. In the long run, the technology can utilise all heat sources, such as solar energy and geothermal energy. The only limits are in our imagination," states Lovvik to the research magazine Apollon at University of Oslo

The new technology will initially be put to use in thermoelectric generators in cars. Several major automobile manufacturers are already interested. Lovvik and his colleagues are currently discussing the situation with General Motors.

"Modern cars need a lot of electricity. By covering the exhaust system with thermoelectric plates, the heat from the exhaust system can increase the car's efficiency by almost ten per cent at a single stroke. If we succeed, this will be a revolution in the modern automotive industry."

The new technology can also replace the hum of today's refrigerator.

"In the future, refrigerators can be soundless and built into cabinets without any movable parts and with the possibility of maintaining different temperatures in each compartment.

In order to extract as much energy as possible, the temperature difference should be as large as possible.

"Initially then, we want to utilise high-temperature waste heat, but there is also an upper limit."

If it becomes too hot, some materials will break down either by melting or by being transformed into other materials. That would mean that they wouldn't work any more.

Apparently self-contradictory.

In order to create thermoelectric materials, physicists have to resolve an apparent paradox. A metal conducts both electricity and heat. An insulator conducts neither electricity nor heat.

A good thermoelectric material ought to be a semi-conductor with very special properties: Its thermal resistance must be as high as possible at the same time as current must flow through it easily.

"This is not a simple combination, and it may even sound like a self-contradiction. The best solution is to create small structures that reflect the heat waves at the same time as the current is not reflected."

In order to understand why this is so, you must first understand how heat is dissipated. When a material becomes hot, the atoms vibrate. The hotter it becomes, the greater the vibrations, and when an atom vibrates, it will also affect the vibration of the adjacent atom.

When these vibrations spread through the material, they can be called heat waves. If we create barriers in the material so that some atoms vibrate at different frequencies from their adjacent atoms, the heat will not be so easily dissipated.

"Moreover, the atomic barrier must be created in such a way that it does not prevent the electric current from flowing through it."

Grinding nano-cavities at minus 196 degrees.

The scientists have found a method of creating these atomic barriers. The barriers are introduced densely in the special semi-conductors.

"We have achieved this by using a completely new "mill." Just as the miller grinds grain, the scientists will grind down semi-conductors to nano-sized grains. They will do that by cooling them down with liquid Nitrogen to minus 196 degrees. That makes the material more brittle, less sticky and easier to crush. It is important to grind down the grains as small as possible. Afterwards the grains are glued back together again, and in this way the barriers are created."

"The small irregularities in the barriers reflect the heat waves," says Lovvik.

The team of scientists uses an electron microscope to examine the micro-structures in the material.

"We have now discovered new nano-cavities in the materials and learned more about how they reflect heat waves."

The thermal resistance is measured in the Norwegian Micro and Nano Laboratories that are jointly operated by UiO and SINTEF. Lovvik's specialised field is mathematical models. With these models, he can predict how the atoms should be arranged in the materials.

Renaissance for cobalt

The scientists are now searching for the next generation of thermoelectric materials. They have just tested the cobalt arsenide mineral, skutterudite, which may be found at Skutterud at Blafarvevarket in Modum, Norway.

"It was just recently discovered that skutterudite may have atoms located in small nano-cavities. These cavities act as barriers to heat dissipation," concludes Lovvik.

Story Source:

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

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

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

Friday, November 25, 2011

Ionized plasmas as cheap sterilizers for developing world

University of California, Berkeley, scientists have shown that ionized plasmas like those in neon lights and plasma TVs not only can sterilize water, but make it antimicrobial -- able to kill bacteria -- for as long as a week after treatment.

Devices able to produce such plasmas are cheap, which means they could be life-savers in developing countries, disaster areas or on the battlefield where sterile water for medical use -- whether delivering babies or major surgery -- is in short supply and expensive to produce.

"We know plasmas will kill bacteria in water, but there are so many other possible applications, such as sterilizing medical instruments or enhancing wound healing," said chemical engineer David Graves, the Lam Research Distinguished Professor in Semiconductor Processing at UC Berkeley. "We could come up with a device to use in the home or in remote areas to replace bleach or surgical antibiotics."

Low-temperature plasmas as disinfectants are "an extraordinary innovation with tremendous potential to improve health treatments in developing and disaster-stricken regions," said Phillip Denny, chief administrative officer of UC Berkeley's Blum Center for Developing Economies, which helped fund Graves' research and has a mission of addressing the needs of the poor worldwide.

"One of the most difficult problems associated with medical facilities in low-resource countries is infection control," added Graves. "It is estimated that infections in these countries are a factor of three-to-five times more widespread than in the developed world."

Graves and his UC Berkeley colleagues published a paper in the November issue of the Journal of Physics D: Applied Physics, reporting that water treated with plasma killed essentially all the E. coli bacteria dumped in within a few hours of treatment and still killed 99.9 percent of bacteria added after it sat for seven days. Mutant strains of E. coli have caused outbreaks of intestinal upset and even death when they have contaminated meat, cheese and vegetables.

Based on other experiments, Graves and colleagues at the University of Maryland in College Park reported Oct. 31 at the annual meeting of the American Vacuum Society that plasma can also "kill" dangerous proteins and lipids -- including prions, the infectious agents that cause mad cow disease -- that standard sterilization processes leave behind.

In 2009, one of Graves' collaborators from the Max Planck Institute for Extraterrestrial Physics built a device capable of safely disinfecting human skin within seconds, killing even drug-resistant bacteria.

"The field of low-temperature plasmas is booming, and this is not just hype. It's real!" Graves said.

In the study published this month, Graves and his UC Berkeley colleagues showed that plasmas generated by brief sparks in air next to a container of water turned the water about as acidic as vinegar and created a cocktail of highly reactive, ionized molecules -- molecules that have lost one or more electrons and thus are eager to react with other molecules. They identified the reactive molecules as hydrogen peroxide and various nitrates and nitrites, all well-known antimicrobials. Nitrates and nitrites have been used for millennia to cure meat, for example.

Graves was puzzled to see, however, that the water was still antimicrobial a week later, even though the peroxide and nitrite concentrations had dropped to nil. This indicated that some other reactive chemical -- perhaps a nitrate -- remained in the water to kill microbes, he said.

Plasma discharges have been used since the late 1800s to generate ozone for water purification, and some hospitals use low-pressure plasmas to generate hydrogen peroxide to decontaminate surgical instruments. Plasma devices also are used as surgical instruments to remove tissue or coagulate blood. Only recently, however, have low-temperature plasmas been used as disinfectants and for direct medical therapy, said Graves, who recently focused on medical applications of plasmas after working for more than 20 years on low-temperature plasmas of the kind used to etch semiconductors.

"I'm a chemical engineer who applies physics and chemistry to understanding plasmas," Graves said. "It's exciting to now look for ways to apply plasmas in medicine."

Graves' UC Berkeley coauthors are former post-doctoral fellow Matthew J. Traylor; graduate students Matthew J. Pavlovich and Sharmin Karim; undergraduate Pritha Hait; research associate Yukinori Sakiyama; and chemical engineer Douglas S. Clark, The Warren and Katharine Schlinger Distinguished Professor in Chemical Engineering and the chair of the Department of Chemical and Biomolecular Engineering.

The work on deactivating dangerous and persistent biological molecules was conducted with a group led by Gottlieb Oehrlein, a professor of materials science and engineering at the University of Maryland in College Park.

The research is supported by the U.S. Department of Energy's Office of Fusion Science Plasma Science Center, the UC Berkeley Blum Center for Developing Economies, and the UC Berkeley Sustainable Products and Solution Program.

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The above story is reprinted from materials provided by University of California - Berkeley. The original article was written by Robert Sanders, Media Relations.

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Journal Reference:

Matthew J Traylor, Matthew J Pavlovich, Sharmin Karim, Pritha Hait, Yukinori Sakiyama, Douglas S Clark, David B Graves. Long-term antibacterial efficacy of air plasma-activated water. Journal of Physics D: Applied Physics, 2011; 44 (47): 472001 DOI: 10.1088/0022-3727/44/47/472001

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Engineers solve energy puzzle: How energy levels align in a critical group of advanced materials

 University of Toronto materials science and engineering (MSE) researchers have demonstrated for the first time the key mechanism behind how energy levels align in a critical group of advanced materials. This discovery is a significant breakthrough in the development of sustainable technologies such as dye-sensitized solar cells and organic light-emitting diodes (OLEDs).

Transition metal oxides, which are best-known for their application as super-conductors, have made possible many sustainable technologies developed over the last two decades, including organic photovoltaics and organic light-emitting diodes. While it is known that these materials make excellent electrical contacts in organic-based devices, it wasn't known why -- until now.

In research published in Nature Materials, MSE PhD Candidate Mark T. Greiner and Professor Zheng-Hong Lu, Canada Research Chair (Tier I) in Organic Optoelectronics, lay out the blueprint that conclusively establishes the principle of energy alignment at the interface between transition metal oxides and organic molecules.

"The energy-level of molecules on materials surfaces is like a massive jigsaw puzzle that has challenged the scientific community for a very long time," says Professor Lu. "There have been a number of suggested theories with many critical links missing. We have been fortunate to successfully build these links to finally solve this decades-old puzzle."

With this piece of the puzzle solved, this discovery could enable scientists and engineers to design simpler and more efficient organic solar cells and OLEDs to further enhance sustainable technologies and help secure our energy future.

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The above story is reprinted from materials provided by University of Toronto Faculty of Applied Science & Engineering.

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Journal Reference:

Mark T. Greiner, Michael G. Helander, Wing-Man Tang, Zhi-Bin Wang, Jacky Qiu, Zheng-Hong Lu. Universal energy-level alignment of molecules on metal oxides. Nature Materials, 2011; DOI: 10.1038/nmat3159

Robot speeds up glass development

Model by model, the electronics in a car are being moved closer to the engine block. This is why the materials used for the electronics must resist increasing heat -- so the glass solder being used as glue must be continually optimized. For the first time ever, a robot takes on the task of developing new types of glass and examining their characteristics. Researchers will introduce this robot at the "productronica" trade fair to be held in Munich, Germany, from November 15 -- 18, 2011.

For laymen glas looks like glass -- it might be a window, a drinking vessel, a lense for an automotive headlight. But there is much more in and to the transparent material: glass can consist of 50 to 60 different elements. Experts are constantly being asked to create glass with certain characteristics out of these elements, since new applications require new materials quite often. Let's take the car as an example: the electronic components in a car's engine compartment are being brought ever closer to the engine and so must increasingly be resistant to heat and corrosive gasses. This also applies to the glue, a glass solder. In the development of fuel cells, the demand for new types of glass is also great: the use of new metals requires that the glass solder also be adapted. In addition, over a period of approximately 100,000 hours, the glass must withstand thermal heat of 900 degrees Celsius without being damaged.

In order to develop glass with new characteristics, experts select about ten compounds from potential elements, mix them and then heat the powder. They heat it in a furnace until it is soft, then they pour it into a mould and let it cool slowly and in a controlled fashion, down to room temperature. During that process small samples from the viscous glass are taken to test it: how viscous is it? How well does it wet metals? How does it crystallize out? To produce the glass samples by hand and to test them requires a lot of time: one employee needs approximately two weeks to process 16 samples.

Researchers of the Fraunhofer Institute for Silicate Research ISC in Würzburg have developed a unit that carries out all these steps automatically. "It needs only 24 hours to process 16 samples," says Dr. Martin Kilo, manager of the expert group for glass and high-temperature materials at the ISC. "For this reason we are able to develop glass elements more cost-effectively than previously, by up to 50 percent." The core piece of the unit is a robot: it puts a mixing cup on a scale and moves it under 14 storage vessels, from which a certain amount of powder is filled into the cup. Then the robot mixes the individual ingredients by closing the cup and shaking it, just like a bartender does with a cocktail shaker. The robot arm then grabs a crucible, puts it onto the scale, fills it with a certain amount of the mixed powder and puts the crucible into one of the five furnaces available in total. The robot repeats this steps several times, since gases build up when the powder is heated and foam could form otherwise. In addition, the powder shrinks during the melting process. Finally the furnace heats the fully filled crucible to a higher temperature, causing the gas bubbles in the glass to rise to the surface. Once the glass is viscous, the robot arm removes the crucible, pours the glass into a new mould and places it in a stress-relieving furnace. Here, the glass cools slowly and in a controlled manner, from 600 to 800 degrees Celsius down to room temperature.

An additional central element of the unit is the analysis unit. It works according to the thermo-optical measurement principle. Looking through two measurement windows, the shade the sample projects in a backlight test system is recorded by a CCD camera. The changes in the contour make it possible to determine characteristics such as sample volume, hemisphere point and wetting angle. This test unit measures how viscous the melt is, and if and how it crystallizes and wets metals. The test unit can also be used independently of the glass screening unit. The unit also determines and records the ability of the glass to conduct heat.

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The above story is reprinted from materials provided by Fraunhofer-Gesellschaft.

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