Putting the 'fuel' in biofuels

Recent discussions of methods by which biomass -- grasses, trees, and other vegetation -- could be turned into fuel makes a lot of sense in theory. Plant matter is composed of energy-intensive carbohydrates, but even now scientists still don't have the perfect solution for converting plant sugars into combustible fuels.

"There's a real challenge in the catalysis and conversion process that we face, which is that nature and evolution have already fashioned far better catalysts than we could create on our own—namely enzymes," said materials scientist Christopher Marshall, who leads the Institute for Atom-Efficient Chemical Transformations (IACT) at the U.S. Department of Energy's (DOE) Argonne National Laboratory. "In order to aid the transition away from a petroleum-based economy, we have to take our cues from the catalysts that have existed for millions of years."

Using actual biological enzymes would not be a workable solution, since enzymes work too slowly to be effective. For the purposes of converting biomass to biofuels, researchers need to synthesize biologically-inspired inorganic catalysts that balance the need for molecular specificity and high reaction rates.

"When it comes to catalyst discovery, everything's based around a particular set of trade-offs," Marshall said.

Potential catalysts for biofuel production have traditionally come from the precious metals and their elemental cousins. According to Marshall, scientists have found an increasing spectrum of applications first for platinum, and then for a platinum-molybdenum hybrid. "Slightly different chemistries can produce dramatically different results both in terms of efficiencies and specificities," he said. "We're really just trying to fashion the best molecular jigsaw pieces we can to fit this larger puzzle."

IACT was founded in 2009 as part of the DOE's effort to establish a set of several dozen Energy Frontier Research Centers (EFRCs) around the country that would contain five-year interdisciplinary programs focused around discrete scientific challenges. As part of the overall effort to transform the energy economy, Argonne also leads research into improved lithium-ion battery technology and new photovoltaic devices that can better capture solar energy.

Converting biomass to biofuels requires the use of a great deal of hydrogen, an element that Marshall said can be hard to manufacture. "The current methods of getting the hydrogen we need to do the conversion require the input of just as much energy as we'd get out of the fuels we'd be trying to create," he said. "In order to really get biofuels to take off, we first have to tackle the problem of where we're going to get all the hydrogen we need."

Because hydrogen is contained within the carbohydrate backbone of plant matter, ideally scientists hope to find a self-sustaining process in which the hydrogen needed for the conversion of biomass to biofuels can be extracted from the biomass itself. To do so requires the development of robust inorganic materials based on nanotechnology that can improve the multistep process of going from woodchipper to gas tank.

Researchers who collaborate in the IACT come from a variety of different technical backgrounds, including materials design, synthesis and characterization, theoretical chemistry and computational studies. "By combining all of these approaches, we hope to gain an understanding of how these key reactions work and how we can optimize the effectiveness of these catalysts both in terms of their selectivity and their rate of reaction. We want to use these catalysts as scalpels, not chainsaws," Marshall said.

Provided by Argonne National Laboratory (news : web)

Cystic fibrosis bacteria could help fight back against antibiotic resistance

A bacteria which infects people with cystic fibrosis could help combat other antibiotic-resistant microbes, according to a team from Cardiff and Warwick Universities.

Continuous use of existing antibiotics means that resistant bacteria are now causing major health problems all over the world. New antibiotics are urgently needed to combat the emergence of multidrug-resistant bacteria such as the MRSA superbug.

Now a surprising source of hope has emerged in the form of Burkholderia, a group of bacteria which can cause severe lung infections in people with the genetic disorder cystic fibrosis. However, the Cardiff and Warwick team has now discovered antibiotics from Burkholderia are effective against MRSA and even other cystic fibrosis infecting bacteria.

Dr Eshwar Mahenthiralingam, of Cardiff University's School of Biosciences, Cardiff University, has been studying Burkholderia for the last decade. Using forensic fingerprinting tests to genetically identify the bacteria, Dr Mahenthiralingam's research group has tracked strains all over the world and helped develop guidelines to prevent it spreading.

By the summer of 2007, Dr Mahenthiralingam had built up a large collection of Burkholderia bacteria. He and his team then decided to screen them for antibiotics active against other bacteria, particularly drugs with the potential to kill other bacteria that infect cystic fibrosis patients. Over the next two years, Dr Mahenthiralingam's team discovered that around one quarter of Burkholderia bacteria have very strong antibiotic activity on multidrug-resistant pathogens such as MRSA. One particular strain, Burkholderia ambifaria, was found to produce two very potent antibiotics active on resistant bacteria, in particular Acinetobacter baumanii.

The chemical structures of the antibiotics, called enacyloxins, were determined by Professor Gregory Challis and Dr. Lijiang Song at the University of Warwick, demonstrating that they belong to one of the most successful families of natural product drugs, the polyketides. Other examples of polyketides include erythromycin, which is used to cure many bacterial infections, and doxorubin, used as an anti-cancer drug. Professor Challis commented: "The combination of enzymes used by Burkholderia to make the enacyloxins is very unusual. Our insights into this process should allow us to use cutting edge synthetic biology techniques to produce novel enacyloxin analogues with improved pharmaceutical properties."

The team's findings have now been published in the journal Chemistry and Biology. Dr Mahenthiralingam commented: "Burkholderia are soil bacteria like Streptomyces, which are the source of most of our current antibiotics. Our research therefore offers real hope of a completely new source for the identification and engineering of highly potent antibiotics. With antibiotic resistant bacteria causing great suffering around the world, these new sources are urgently needed."

The chemical structures of the antibiotics, called enacyloxins, were determined by Professor Gregory Challis and Dr. Lijiang Song at the University of Warwick, demonstrating that they belong to one of the most successful families of natural product drugs, the polyketides. Other examples of polyketides include erythromycin, which is used to cure many bacterial infections, and doxorubin, used as an anti-cancer drug. Professor Challis commented: "The combination of enzymes used by Burkholderia to make the enacyloxins is very unusual. Our insights into this process should allow us to use cutting edge synthetic biology techniques to produce novel enacyloxin analogues with improved pharmaceutical properties."

Provided by Cardiff University (news : web)

Details of new type of electric car battery released

After being spun off from parent company A123 Systems last year; the new offspring, 24M has published a paper in Advanced Energy Materials, ending months of speculation about what it has been working on. It was no secret that the new project was to advance work on a new type of battery that A123 had been working on for a couple of years; namely a battery that could be used to replace the lithium-ion batteries currently used in electric cars. Now, with the paper’s release it's clear that the new battery, similar to a flow battery, uses a liquid material to hold the charge, rather than conventional dry fuel cells, and if successful could do away with a lot of the non-charge holding stuff that makes up nearly three quarters of the bulk of current electric car batteries.

Assisted by a grant from the U.S. Advanced Research Projects Agency-Energy (ARPA-E), to help fund research between the new start-up, MIT and Rutgers University, the new battery, based on research done by Yet-Ming Chiang who is both a professor at MIT and founder of A123 Systems and 24M, if successful, would allow for upsizing of car batteries without adding any non-chargeable material, greatly increasing its density, which would in turn, theoretically greatly reduce the cost of the battery pack in an electric vehicle. Current battery packs now constitute up to a third of the total vehicle price.

The new battery, as described in the paper, uses a sludge-like material contained in storage tanks, rather than dry cells; one positively charged, the other negative. To get the charge from the battery, the materials are pumped through channels allowing ions to move freely between the two and eventually to an external circuit. To facilitate the transfer of electrons from the sludge, nanoscale particles that help to form networks that give the electrons a path to follow were developed and added to the sludge mix. In this type of battery, the amount of storage capacity goes up as the tank size is increased, with no additional materials needed, in sharp contrast to lithium batteries.

The battery is not yet ready for prime time though, as a current model of the battery would be bulky and the electrical conductivity, according to Change, is still far below what would be needed in a real world battery in an actual electrical vehicle; research is still ongoing, as he and his team try to figure out how to increase the concentration of the active materials in the sludge.

More information: Semi-Solid Lithium Rechargeable Flow Battery, Advanced Energy Materials, Article first published online: 20 MAY 2011 DOI: 10.1002/aenm.201100152

Abstract
A new kind of flow battery is fueled by semi-solid suspensions of high-energy-density lithium storage compounds that are electrically ‘wired’ by dilute percolating networks of nanoscale conductor particles. Energy densities are an order of magnitude greater than previous flow batteries; new applications in transportation and grid-scale storage may result.

? 2010 PhysOrg.com

New mass spectrometry technique clouds early European inflation theories

Using a new coupled mass spectrometry technique that employs multiple collectors, researchers in France have shown that it was not an influx of silver from the America's that caused high inflation in Europe from the early 1500's to mid 1600, as some historians have long believed. Their results, published in the Proceedings of the National Academy of Sciences (PNAS) show that the gradual replacement of coins made from Spanish silver to imported Mexican silver, did not occur until nearly fifty years later.

The research, led by Anne-Marie Desaulty, sought to answer once and for all the question of why the whole of Europe experienced a dramatic, inexplicable rise in overall prices, shortly after the discovery of the new world.

Until now, researchers have had to rely on the results of mass spectrometry analysis of lead and copper found in coins to trace its origins, because the results obtained from doing so on silver couldn’t be trusted. Unfortunately, due to the difficulty of reading isotope results for lead, and the fact that copper was used at later dates to re-mint coins, no real conclusions could be drawn from the results of such tests. Now however, using the new technique, the team was able to discern that silver from Mexico didn’t begin appearing in Spanish coins until the inflationary period was over; though it did become the principal source of silver in such coins thereafter.

In the past, mass spectrometry tests on silver were fraught with difficulty due to the ratio of its two stable isotopes, silver-107 and 109; making them extremely difficult to measure. New advances in mass spectrometry devices however, coupled with multiple collectors, has made the process more sensitive; sensitive enough so that the results of such tests can now be trusted; and those findings suggest that it was not the sudden importation of Mexican silver as a means of minting Spanish coins that led to the inflation, because there simply wasn’t enough of it present in coins during the period in question.

Unfortunately though, because the study was able to rule out the influx of Mexican silver as a cause for the inflation, a new gap in knowledge has been left behind, which will send scholars and researchers back to the drawing boards to explain why in fact, prices in Europe rose as they did, and why it happened for so long.

More information: Isotopic Ag–Cu–Pb record of silver circulation through 16th–18th century Spain, PNAS, Published online before print May 23, 2011, doi: 10.1073/pnas.1018210108

Abstract
Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th–18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver.

 

Penn researchers help nanoscale engineers choose self-assembling proteins

 

Engineering structures on the smallest possible scales -- using molecules and individual atoms as building blocks -- is both physically and conceptually challenging. An interdisciplinary team of researchers at the University of Pennsylvania has now developed a method of computationally selecting the best of these blocks, drawing inspiration from the similar behavior of proteins in making biological structures.

The team was led by postdoctoral student Gevorg Grigoryan and professor William DeGrado of the Department of Biochemistry and Biophysics in Penn’s Perelman School of Medicine, as well as graduate student Yong Ho Kim of the Department of Chemistry in Penn’s School of Arts and Sciences. Their colleagues included members of the Department of Physics and Astronomy in SAS.

Their research was published in the journal Science last week.  

The team set out to design proteins that could wrap around single-walled carbon nanotubes. Consisting of a cylindrical pattern of carbon atoms tens of thousands of times thinner than a human hair, nanotubes are enticing to nanoengineers as they are extraordinarily strong and could be useful as platform for other nano-structures.

“We wanted to achieve a specific geometric pattern of the atoms that these proteins are composed of on the surface of the nanotube,” Grigoryan said. “If you know the underlying atomic lattice, it means that you know how to further build around it, how to attach things to it. It's like scaffolding for future building.”

The hurdle in making such scaffolds isn’t a lack of information, but a surfeit of it: researchers have compiled databases that list hundreds of thousands of actual and potential protein structures in atomic detail. Picking the building materials for a particular structure from this vast array and assuring that they self-assemble into the desired shape was beyond the abilities of powerful computers, much less humans.  

“There's just an enormous space of structural possibilities to weed through trying to figure out which are feasible,” Grigoryan said. “To have a process that can do that quickly, that can look at a structure and say ‘that's not reasonable, that can't be built out of common units,’ would solve that problem.”

The researchers’ algorithm works in three steps, which, given the parameters of the desired scaffolding, successively eliminate proteins that will not produce the right shape. The elimination criteria were based on traits like symmetry, periodicity of binding sites  and similarity to protein “motifs” found in nature. 

After separating the wheat from the chaff, the result is a list of thousands of candidate proteins. While still a daunting amount, the algorithm makes the protein selection process merely difficult, rather than impossible.

The research team tested their algorithm by designing a protein that would not only stably wrap around a nanotube in a helix but also provide a regular pattern on its exterior to which gold particles could be attached.

“You could use this to build a gold nanowire, for instance, or modulate the optical properties of the underlying tube in desired ways” Grigoryan said.

Next steps will include applying this algorithm for designing proteins that can attach to graphene, which is essentially an unrolled nanotube. Being able to make scaffolds out of customizable array of proteins in a variety of shapes could lead to advances in everything from miniaturization of circuitry to drug delivery. 

Engineering these materials in the lab requires a tremendous amount of precision and computational power, but such efforts are essentially mimicking a phenomenon found in even the simplest forms of life.  

“The kind of packing that certain viruses have in their viral envelope is similar to what we have here in that they self-assemble. They have protein units that, on their own, form their complicated structures with features that are far beyond the size of any single protein,” Grigoryan said. “Each protein doesn’t know what the final structure is going to be, but it still helps form it. We were inspired by that.”

Provided by University of Pennsylvania (news : web)