Monday, February 6, 2012

TU Berlin receives more than one million dollars in funding from the United States for catalysis research

"In the field of electromobility mainly research on lithium-ion battery technology has been promoted in the past years. But the limits of this technology become more and more obvious," states Peter Strasser, a professor for chemical engineering at the TU Berlin and member of the Cluster of Excellence "Unifying Concepts in Catalysis" (UniCat).

"Thereby the idea of hydrogen based e-mobility slowly returns to the center of attention. In this technology a fuel cell, acting as an energy converter, feeds the electrical motor. Conceivably a fuel cell could also be used as a kind of ‘range extender’ - thus as an additional device to increase the cruising range – interacting with a Li-battery."

His research team constitutes part of a high-profile project of the U.S. Department of Energy (DoE), which researches new nano-structured materials. The researchers aim to make the catalytic conversion of hydrogen and oxygen into usable electricity in fuel cells more efficient and less costly. The DoE recently approved a total of 5.3 million U.S. dollars in funding for the next three years, of which approximately $ 1.5 million will go to the TU Berlin.

The TU team works closely with two industrial partners and three academic institutions, namely the Massachusetts Institute of Technology (MIT), Northeastern University and George Washington University.

Hydrogen fuel cells use molecular hydrogen to store energy. Their density is almost 200 times higher than that of a Li-ion battery. In the drive mechanism of the hydrogen-based fuel cell the chemical energy of hydrogen is converted into electrical energy. Although the practical conversion efficiency currently is only about 50 percent, an electric car requires only about six kilograms of hydrogen for a 450 km range, and refueling takes only six minutes. On the other hand, a typical Li-ion battery weighs at least 200 kilograms, takes six to nine hours for loading and provides only enough energy for a range of 200 km. In addition, if the vehicle is solely battery powered it has to be air-conditioned electrically because there is no waste heat. This again can significantly reduce the range.

"When comparing the costs, the fuel cell also scores much better," declares Strasser. "Li-ion batteries currently cost about 300 € per kilowatt hour. In a typical-sized vehicle a range of 200 kilometers amounts to about 12,000 €. Comparable performance characteristics with a fuel cell of the latest generation cost around 5,000 €; in this case the range naturally depends on the size of the tank, not of the fuel cell. "What makes fuel cells expensive is, above all, the precious metal platinum which is used as a catalyst in nanostructured form. Peter Strasser and his colleagues in the joint project want to reduce exactly this part of the costs. So far, 0.8 grams of platinum were needed per kilowatt. The scientists want to reduce this amount to 0.1 grams per kilowatt. At a platinum price of about € 40 per gram, the platinum catalyst would then only make up 400 € of the fuel cell costs. A comparable amount of platinum is currently used in each exhaust catalyst.

The work group led by Professor Strasser has been working on a new family of nanostructured fuel cell catalysts since 2005. They consist of a platinum-poor core surrounded by a thin platinum-rich shell. In the first place this reduces the required amount of platinum; secondly, the platinum-rich shell catalyzes the chemical processes far better than pure platinum. However, the life expectancy of the material during ongoing fuel cell operation is still a challenge. Strasser and his team are looking for ways to stabilize the core-shell configuration with new carrier materials, mainly nitrogen-containing carbon, but also by adding additional metal particles in the nucleus.

"Unifying Concepts in Catalysis" (UniCat) is the sole Cluster of Excellence in Germany researching the economically important field of catalysis. More than 250 chemists, physicists, biologists and engineers from four universities and two Max Planck research institutes from Berlin and Potsdam are involved in this interdisciplinary research network. The Cluster is hosted by the Technische Universität Berlin. UniCat receives funding of approximately € 5.6 million each year as part of the Excellence Initiative of the German Research Foundation.

Avalanche of reactions at the origin of life

Volcanic-hydrothermal flow channels offer a chemically unique environment, which at first glance appears hostile to life. It is defined by in the crust of the earth, through which water flows, laden with are contacting a diversity of minerals. And yet – it is precisely this extreme environment, where the two mechanisms could have emerged, which are at the root of all life: The multiplication of (reproduction) and the emergence of new biomolecules on the basis of previously formed biomolecules (evolution).

At the outset of this concatenation of reactions that led eventually to the formation of cellular forms of life there are only a few , which are formed from volcanic gases by mineral catalysis. Akin to a domino stone that triggers a whole avalanche, these first biomolecules stimulate not only their own further synthesis but also the production of wholly new biomolecules. "In this manner life begins by necessity in accordance with pre-established laws of chemistry and in a pre-determined direction", declares Günter Wächtershäuser, honorary professor for evolutionary biochemistry at the University of Regensburg. He developed the mechanism of a self-generating – theoretically, alas, an experimental demonstration has been lacking so far.

Now, scientists around Claudia Huber and Wolfgang Eisenreich, at the Chair of Biochemistry in the Department of Chemistry at the TUM in close cooperation with Wächtershäuser, managed for the first time to demonstrate experimentally the possibility of such a self-stimulating . A catalyst consisting of compounds of the transition metals nickel, cobalt or iron has the lead role in these reactions. It provides not only for the formation of the first biomolecules, but it also initiates the concatenation of reactions. The reason: The biomolecules just newly formed from the volcanic gases engage the center of the transition metal catalyst to enable further chemical reactions bringing forth wholly new biomolecules. "This coupling between the catalyst and an organic reaction product is the first step", explains Wächtershäuser. "Life arises, if subsequently a whole cascade of further couplings takes place, and this primordial life leads eventually to the formation of genetic material and of the first cells".

The scientists simulated in their experiments the conditions of volcanic-hydrothermal flow channels and established an aqueous-organometallic system that produces a whole suite of different biomolecules, among them the amino acids glycin and alanin. Here the carbon source was provided by a cyano compound and the reducing agent by carbon monoxide. Nickel compounds turned out to be the most effective catalysts in these experiments. The scientists then added the products glycin and alanin to another system, that generated again two new biomolecules. The result: The two amino acids increased the productivity oft he second system by a factor of five.

In future experiments the scientists intend to recreate more precisely the conditions of volcanic-hydrothermal systems, wherein life could have arisen billions of years ago. "For this purpose we simulate first certain stages in the development of a volcanic-hydrothermal flow system in order to determine essential parameters", explains Wächtershäuser. "Only thereafter we may engage in a rational construction of a flow reactor".

The results of the scientists around Wächtershäuser and Eisenreich show that an origin and evolution of life in hot water of volcanic flow ducts is feasible. The results reveal advantages of the theory compared to other approaches. Within the flow ducts temperature, pressure and pH change along the flow path, and thereby a graded spectrum of conditions is offered that is appropriate for all stages of early up to the formation of genetic material (RNA/DNA).

The most important property of the system is its autonomy: As opposed to the notion of a cool prebiotic both, the first metabolism was not dependent on accidental events or an accumulation of essential components over thousands of years. As soon as the first domino stone is toppled, the others will follow automatically. The proceeds along definite trajectories, pre-established by the rules of chemistry – a chemically determined process giving rise to the tree of all forms of life.

More information: Elements of metabolic evolution. C. Huber, F. Kraus, M. Hanzlik, W. Eisenreich, G. Wächtershäuser, Chemistry – A European Journal, advanced online publication: 13 Jan 2012 – DOI: 10.1002/chem.201102914

Provided by Technische Universitaet Muenchen

Hydrogen peroxide goes green in undergrad's published paper on renewable energy

A chemistry major, MacKenzie applies hydrogen peroxide to , sawdust and grass clippings so that they can be more easily converted to biofuels like natural gas. She’s the lead author of an academic journal article on the topic.

What’s more, the hydrogen peroxide changes to water in the process.

“That’s one of the advantages to using this kind of pretreatment,” she said. “A lot of other treatments leave some toxic waste.”

The research could be applied in any setting with a stream of incoming organic waste. At landfills, for example, yard waste could be separated and fed into a machine designed to digest the material and convert it to methane gas. Such equipment is already being developed and used by MacKenzie’s mentor, Professor Jaron Hansen, at dairy farms in Utah and China.

With graduation coming in April, MacKenzie is polishing an Honors thesis that will demonstrate the optimal concentrations of and UV light when processing and grass clippings.

“The thing that gets me most excited is the fact that this is a source,” MacKenzie said. “I feel like I have a responsibility to figure out how to live more sustainably and be cleaner with the energy we use.”

Provided by Brigham Young University (news : web)

Decoding DNA's annotations

The team’s probe can differentiate between two epigenetic markers—methyl and hydroxymethyl markers—that differ by the presence of a single oxygen atom. Methyl groups, one of the first epigenetic markers discovered, are known to inactivate gene expression; ‘demethylation’, or removal of a methyl group from the , allows gene expression to restart. 

“We know the mechanism of DNA methylation, but nobody knows the mechanism of DNA demethylation,” Okamoto explains. One possibility is that the body converts the methyl marker into a hydroxymethyl group, as the first step in the process of removing it, in preparation to reactivate a gene. However, current tests cannot distinguish between the two epigenetic markers, preventing that theory from being tested.

The chemical probe developed by Okamoto and colleagues is based on a peptide called Sp1, which is known to bind to DNA. The researchers previously modified the structure of Sp1 so that it adheres strongly only to DNA strands incorporating a methyl marker (Fig. 1). They then showed that if the peptide binds to a DNA strand, it reveals the presence of the methyl group. 

In their latest study, the researchers showed that modified Sp1 will not bind to DNA when the methyl group is converted to a hydroxymethyl—thereby allowing them to tell the two groups apart. The extra oxygen atom in the hydroxymethyl group disrupts the interaction between the peptide and the DNA, so the two cease to adhere together.

Okamoto and his colleagues are now planning to modify the peptide to detect an even wider range of epigenetic markers, which will allow the study of their role in gene expression. “Our next step is to develop the methods for effective sequencing and detection of DNA containing cytosine, 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxycytosine,” Okamoto says.

More information: Nomura, A, et al.. Discrimination between 5-hydroxymethlcytosine and 5-methylcytosine by a chemically designed peptide. Chemical Communications 47, 8277–8279 (2011).

Nomura, A. & Okamoto, A. Phosphopeptides designed for 5-methylcytosine recognition. Biochemistry 50, 3376–3385 (2011).

Provided by RIKEN (news : web)