MATERIALS ENGINEERING

The design of efficient systems for splitting water into hydrogen and oxygen, driven by sunlight is among the most important challenges facing science today, underpinning the long term potential of hydrogen as a clean, sustainable fuel. But man-made systems that exist today are very inefficient and often require additional use of sacrificial chemical agents. In this context, it is important to establish new mechanisms by which water splitting can take place.

Now, a unique approach developed by Prof. David Milstein and colleagues of the Weizmann Institute’s Organic Chemistry Department, provides important steps in overcoming this challenge. During this work, the team demonstrated a new mode of bond generation between oxygen atoms and even defined the mechanism by which it takes place. In fact, it is the generation of oxygen gas by the formation of a bond between two oxygen atoms originating from water molecules that proves to be the bottleneck in the water splitting process. Their results have recently been published in Science.

Nature, by taking a different path, has evolved a very efficient process: photosynthesis – carried out by plants – the source of all oxygen on Earth. Although there has been significant progress towards the understanding of photosynthesis, just how this system functions remains unclear; vast worldwide efforts have been devoted to the development of artificial photosynthetic systems based on metal complexes that serve as catalysts, with little success. (A catalyst is a substance that is able to increase the rate of a chemical reaction without getting used up.)

The new approach that the Weizmann team has recently devised is divided into a sequence of reactions, which leads to the liberation of hydrogen and oxygen in consecutive thermal- and light-driven steps, mediated by a unique ingredient – a special metal complex that Milstein’s team designed in previous studies. Moreover, the one that they designed – a metal complex of the element ruthenium – is a ‘smart’ complex in which the metal center and the organic part attached to it cooperate in the cleavage of the water molecule.

The team found that upon mixing this complex with water the bonds between the hydrogen and oxygen atoms break, with one hydrogen atom ending up binding to its organic part, while the remaining hydrogen and oxygen atoms (OH group) bind to its metal center.

This modified version of the complex provides the basis for the next stage of the process: the ‘heat stage.’ When the water solution is heated to 100 degrees C, hydrogen gas is released from the complex – a potential source of clean fuel – and another OH group is added to the metal center.

‘But the most interesting part is the third ‘light stage,’’ says Milstein. ‘When we exposed this third complex to light at room temperature, not only was oxygen gas produced, but the metal complex also reverted back to its original state, which could be recycled for use in further reactions.’

These results are even more remarkable considering that the generation of a bond between two oxygen atoms promoted by a man-made metal complex is a very rare event, and it has been unclear how it can take place. Yet Milstein and his team have also succeeded in identifying an unprecedented mechanism for such a process. Additional experiments have indicated that during the third stage, light provides the energy required to cause the two OH groups to get together to form hydrogen peroxide (H2O2), which quickly breaks up into oxygen and water. ‘Because hydrogen peroxide is considered a relatively unstable molecule, scientists have always disregarded this step, deeming it implausible; but we have shown otherwise,’ says Milstein. Moreover, the team has provided evidence showing that the bond between the two oxygen atoms is generated within a single molecule – not between oxygen atoms residing on separate molecules, as commonly believed – and it comes from a single metal center.

Discovery of an efficient artificial catalyst for the sunlight-driven splitting of water into oxygen and hydrogen is a major goal of renewable clean energy research. So far, Milstein’s team has demonstrated a mechanism for the formation of hydrogen and oxygen from water, without the need for sacrificial chemical agents, through individual steps, using light. For their next study, they plan to combine these stages to create an efficient catalytic system, bringing those in the field of alternative energy an important step closer to realizing this goal.

Participating in the research were former postdoctoral student Stephan Kohl, Ph.D. student Leonid Schwartsburd and technician Yehoshoa Ben-David all of the Organic Chemistry Department, together with staff scientists Lev Weiner, Leonid Konstantinovski, Linda Shimon and Mark Iron of the Chemical Research Support Department.

Prof. David Milstein’s research is supported by the Mary and Tom Beck-Canadian Center for Alternative Energy Research; and the Helen and Martin Kimmel Center for Molecular Design. Prof. Milstein is the incumbent of the Israel Matz Professorial Chair of Organic Chemistry.

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Journal reference:

1. Stephan W. Kohl, Lev Weiner, Leonid Schwartsburd, Leonid Konstantinovski, Linda J. W. Shimon, Yehoshoa Ben-David, Mark A. Iron, and David Milstein. Consecutive Thermal H₂ and Light-Induced O₂ Evolution from Water Promoted by a Metal Complex. Science, 2009; 324 (5923): 74 DOI: 10.1126/science.1168600

Researchers have developed a critical part of a hydrogen storage system for cars that makes it possible to fill up a vehicle's fuel tank within five minutes with enough hydrogen to drive 300 miles.

The system uses a fine powder called metal hydride to absorb hydrogen gas. The researchers have created the system's heat exchanger, which circulates coolant through tubes and uses fins to remove heat generated as the hydrogen is absorbed by the powder.

The heat exchanger is critical because the system stops absorbing hydrogen effectively if it overheats, said Issam Mudawar, a professor of mechanical engineering who is leading the research.

"The hydride produces an enormous amount of heat," Mudawar said. "It would take a minimum of 40 minutes to fill the tank without cooling, and that would be entirely impractical."

Researchers envision a system that would enable motorists to fill their car with hydrogen within a few minutes. The hydrogen would then be used to power a fuel cell to generate electricity to drive an electric motor.

The research, funded by General Motors Corp. and directed by GM researchers Darsh Kumar, Michael Herrmann and Abbas Nazri, is based at the Hydrogen Systems Laboratory at Purdue's Maurice J. Zucrow Laboratories. In February, the team applied for three provisional patents related to this technology.

"The idea is to have a system that fills the tank and at the same time uses accessory connectors that supply coolant to extract the heat," said Mudawar, who is working with mechanical engineering graduate student Milan Visaria and Timothée Pourpoint, a research assistant professor of aeronautics and astronautics and manager of the Hydrogen Systems Laboratory. "This presented an engineering challenge because we had to figure out how to fill the fuel vessel with hydrogen quickly while also removing the heat efficiently. The problem is, nobody had ever designed this type of heat exchanger before. It's a whole new animal that we designed from scratch."

The metal hydride is contained in compartments inside the storage "pressure vessel." Hydrogen gas is pumped into the vessel at high pressure and absorbed by the powder.

"This process is reversible, meaning the hydrogen gas may be released from the metal hydride by decreasing the pressure in the storage vessel," Mudawar said. "The heat exchanger is fitted inside the hydrogen storage pressure vessel. Due to space constraints, it is essential that the heat exchanger occupy the least volume to maximize room for hydrogen storage."

Conventional automotive coolant flows through a U-shaped tube traversing the length of the pressure vessel and heat exchanger. The heat exchanger, which is made mostly of aluminum, contains a network of thin fins that provide an efficient cooling path between the metal hydride and the coolant.

"This milestone paves the way for practical on-board hydrogen storage systems that can be charged multiple times in much the same way a gasoline tank is charged today," said Kumar, a researcher at GM's Chemical & Environmental Sciences Laboratory and the GM R&D Center in Warren, Mich. "As newer and better metal hydrides are developed by research teams worldwide, the heat exchanger design will provide a ready solution for the automobile industry."

The researchers have developed the system over the past two years. Because metal hydride reacts readily with both air and moisture, the system must be assembled in an airtight chamber, Pourpoint said.

Research activities at the hydrogen laboratory involve faculty members from the schools of aeronautics and astronautics, mechanical engineering, and electrical and computer engineering.

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MIT engineers have created a kind of beltway that allows for the rapid transit of electrical energy through a well-known battery material, an advance that could usher in smaller, lighter batteries — for cell phones and other devices — that could recharge in seconds rather than hours.

The work could also allow for the quick recharging of batteries in electric cars, although that particular application would be limited by the amount of power available to a homeowner through the electric grid.

The work, led by Gerbrand Ceder, the Richard P. Simmons Professor of Materials Science and Engineering, is reported in the March 12 issue of Nature. Because the material involved is not new — the researchers have simply changed the way they make it — Ceder believes the work could make it into the marketplace within two to three years.

State-of-the-art lithium rechargeable batteries have very high energy densities — they are good at storing large amounts of charge. The tradeoff is that they have relatively slow power rates — they are sluggish at gaining and discharging that energy. Consider current batteries for electric cars. "They have a lot of energy, so you can drive at 55 mph for a long time, but the power is low. You can't accelerate quickly," Ceder said.

Why the slow power rates? Traditionally, scientists have thought that the lithium ions responsible, along with electrons, for carrying charge across the battery simply move too slowly through the material.

About five years ago, however, Ceder and colleagues made a surprising discovery. Computer calculations of a well-known battery material, lithium iron phosphate, predicted that the material's lithium ions should actually be moving extremely quickly.

"If transport of the lithium ions was so fast, something else had to be the problem," Ceder said.

Further calculations showed that lithium ions can indeed move very quickly into the material but only through tunnels accessed from the surface. If a lithium ion at the surface is directly in front of a tunnel entrance, there's no problem: it proceeds efficiently into the tunnel. But if the ion isn't directly in front, it is prevented from reaching the tunnel entrance because it cannot move to access that entrance.

Ceder and Byoungwoo Kang, a graduate student in materials science and engineering, devised a way around the problem by creating a new surface structure that does allow the lithium ions to move quickly around the outside of the material, much like a beltway around a city. When an ion traveling along this beltway reaches a tunnel, it is instantly diverted into it. Kang is a coauthor of the Nature paper.

Using their new processing technique, the two went on to make a small battery that could be fully charged or discharged in 10 to 20 seconds (it takes six minutes to fully charge or discharge a cell made from the unprocessed material).

Ceder notes that further tests showed that unlike other battery materials, the new material does not degrade as much when repeatedly charged and recharged. This could lead to smaller, lighter batteries, because less material is needed for the same result.

"The ability to charge and discharge batteries in a matter of seconds rather than hours may open up new technological applications and induce lifestyle changes," Ceder and Kang conclude in their Nature paper.

This work was supported by the National Science Foundation through the Materials Research Science and Engineering Centers program and the Batteries for Advanced Transportation Program of the U.S. Department of Energy. It has been licensed by two companies.

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Journal reference:

1. Byoungwoo Kang & Gerbrand Ceder. Battery materials for ultrafast charging and discharging. Nature, 2009; 458 (7235): 190 DOI: 10.1038/nature07853

Car doors are usually assembled from several sections of sheet metal which are welded together by laser. The laser beam moves over the slightly overlapping sheets and melts them in a spot measuring several tenths of a millimeter, producing a so called full penetration hole that closes again when the laser beam moves on.

It is most important for the laser output power to be set correctly – if it is too low the strength of the welding connection is reduced because it does not extend over the full cross section of the metal sheets, if it is too high the laser cuts right through them.

Until now welders have gauged the right laser output by trial and error and then kept it constant. A complicating factor exists, however, in that the protective glass gets dirty after a while and lets less laser light through onto the metal. If this happens earlier than usual, hours can pass before it is noticed and the metal sheets may not be properly welded. Today, welding processes are only monitored without adjustment of the laser power because the achievalble frame rate of about thousand evaluated images per second is not sufficient. For a closed loop control, frame rates of more than 10 kilohertz – equivalent to 10,000 images per second – are needed for a robust surveillance of the rapidly moving full penetration hole.

Researchers at the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg have now developed a control system for laser welding processes which adapts the output to the given situation.

"Our system analyzes 14,000 images per second and uses the acquired data to adjust the laser output," explains IPM project manager Andreas Blug.

So how does the system manage to analyze the images more than ten times faster than conventional software? "We use special cameras in which a tiny processor is integrated in each pixel. All these processors – 25,000 in total – work simultaneously. In conventional image processing systems the data are handled consecutively by just a small number of computer processors," says Blug.

The new systems are referred to as "Cellular Neural Networks" (CNN). Just a few microseconds after the image is taken the camera delivers an analyzed picture of the contours of the full penetration hole. For small holes the system increases the output, for large ones it reduces it. "In developing this adjustment system we have achieved the first industrial application of CNN technology," says Blug. A prototype already exists, and the researchers now intend to test the system in production.

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Scientists have found that graphite behaves like a semiconductor in ultrafast time scales. The results are of fundamental importance for future electronic devices based on carbon, in which high electrical fields or frequencies are processed.

Nanomaterials like carbon possess unique properties, which have led to first applications in novel electronic devices and sensors. These materials are based on ordered, atomically thin layers of carbon atoms, for example in the form of a single layer as so-called “graphene”, or rolled-up in carbon nanotubes. The electronic properties of such structures are closely related to those of graphite, which consists of a stack of graphene sheets.

Despite intensive research in the past, the fundamental behavior of electrons in this material are not fully understood and still controversially debated.

Markus Breusing, Claus Ropers und Thomas Elsaesser, three scientists from the Max-Born-Institute in Berlin, have now investigated the behavior of electrons in thin graphite films in real time.

As they now report in Physical Review Letters,* they recorded the dynamics of electrons with an unprecedented temporal resolution of only 10 femtoseconds (one femtosecond is a millionth of a billionth of a second). Electrons were excited to high energy states with ultrashort laser pulses, and their return to equilibrium was observed. The individual steps of this process are temporally resolved, and the momentary distribution of electrons in the material is identified. Within 30 femtoseconds, electrons form a hot gas with temperatures of 2500 °C, which cools down to about 200 °C in only 500 femtoseconds. The energy dissipated in this process is transferred to the crystal lattice. After this process, the electrons slowly return to their initial states.

For the first time, the study shows conclusively that, on ultrashort time scales, graphite behaves like a semiconductor, such as silicon or gallium arsenide, and not like a metal.

The observed dynamics have significant consequences for electrical transport, such as currents flowing through the material at high frequencies. The results are of fundamental importance for future electronic devices based on carbon, in which high electrical fields or frequencies are processed.

*Volume 102, Issue 08, 086809/1-4, 2009

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Microscopic particles of carbon known as buckyballs may be able to keep the nation's water pipes clear in the same way clot-busting drugs prevent arteries from clogging up.

Engineers at Duke University have found that buckyballs hinder the ability of bacteria and other microorganisms to accumulate on the membranes used to filter water in treatment plants. This attribute leads the researchers to believe that coating pipes and membranes with these nanoparticles may prove to be an effective strategy for addressing one of the major problems and costs of treating water.

"Just as plaque can build up inside arteries and reduce the flow of blood, bacteria and other microorganisms can over time attach and accumulate on water treatment membranes and along water pipes," said So-Ryong Chae, post-doctoral fellow in Duke's environmental and civil engineering department. The results of his experiments were published March 5, 2009 in the Journal of Membrane Sciences.

"As the bacteria build up on these surfaces, they attract other organic matter, creating a biofilm that slowly builds up over time," Chae continued, "The results of our experiments in the laboratory indicate that buckyballs may be able to prevent this clogging, known as biofouling. The only other options to address biofouling are digging up the pipes and replacing the membranes, which can be expensive and inconvenient."

A buckyball, or C60, is one shape within the family of tiny carbon shapes known as fullerenes. They are named after Richard Buckminster Fuller, the inventor of the geodesic dome, since their shape resembles his famous structure.

"Biofouling is viewed as one of the biggest costs associated with membrane-based water treatment systems," said Claudia Gunsch, assistant professor of civil engineering at Duke's Pratt School of Engineering and senior member of the research team. "These membranes have very small pores, so they can get stopped up quickly. If we could increase the time between membrane replacements by 50 percent, for example, that would be a huge cost savings."

According to Chae, the addition of buckyballs to treatment membranes had a two-fold effect. First, treated membranes showed less bacterial attachment than non-treated membranes. After three days, the membranes treated with buckyballs had on average 20 colony forming units, the method by which bacterial colonies are counted.

"In contrast, the number of bacterial colonies on the untreated membrane was too numerous to count," Chae said.

Chae also found that the presence of the buckyballs inhibited respiration, or the ability of the bacteria to use oxygen to fuel its activities.

"As the concentration of buckyballs increased, so did the inhibition of respiration," Chae said. "This respiratory inhibition and anti-attachment suggests that this nanoparticle may be useful as an anti-fouling agent to prevent the biofouling of membranes or other surfaces."

Gunsch said the mechanisms involved are not well-understood.

Both Gunsch and Chae believe that since buckyballs are one of the most widely used nanoparticles, additional research is needed to determine if they have any detrimental effects on the environment or to humans. This is one of many issues being studied at Duke's Center for Environmental Implications of Nanotechnology.

"We need to figure out how resistant these coatings will be to long-term use," Gunsch said. "If they can indeed prevent fouling, they will last longer. If they slough off over time, we need to know what the effects will be."

The current experiments in the laboratory were conducted with Escherichia coli K12, a strain of the bacteria that is widely used in laboratory experiments.

"We focused on a quite specific microorganism, so the next stage of our research will to see if these nanoparticles will have the same effects on bacteria commonly found in the environment or those in mixed microbial communities," Chae said. "We also plan to build a small-scale version of a treatment plant in the lab to conduct these tests."

The research was supported by the Office of Naval Research, National Science Foundation and the Korea Research Foundation. Other Duke members of the team were Shuyi Wang, Zachary Hendren and Mark R. Wiesner. Yoshimasa Watanabe, Hokkaido University, Japan, was also part of the team.

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Researchers at Uppsala University have managed for the first time to measure magnetic properties in new materials quantitatively with the help of electron microscopy – with unparalleled precision. The secret behind the breakthrough is a successful elaboration of electron microscope technology.

The findings, published in the scientific journal Physical Review Letters, means that the energy loss entailed in all electromagnetic materials can ultimately be minimized.

Apace with the miniaturization of electronic components, new methods are needed to analyze the properties of materials down to the atomic level. In 2006 a scientific article showed that it is possible to use a transmission electron microscope to study the magnetic properties of a material, using a technique called “Electron Magnetic Circular Dichroism,” (EMCD). As different materials are combined, often in thin atomic monolayer films, exciting new magnetic properties are created.

This is an interesting research field that is used in hard drives, for example. Today scientists are primarily studying magnetic properties with the aid of an extremely expensive synchrotron light source, whereas EMCD affords a cheaper and considerably more detailed study of the magnetic properties of each layer down to one nanometer.

Until now it has only been shown that EMCD works qualitatively. The Uppsala University researchers have further elaborated the technology to enable it to measure the magnetic forces of the sample quantitatively as well.

“This means we can put a number on the magnetic strength of the sample, which is key to understanding how various materials interact,” says Klaus Leifer, professor of experimental physics at the Department of Engineering Sciences.

By combining practical experiments and theoretical calculations, the method of measuring the EMCD signal has now been optimized and the computer processing of the experimental data further developed. The article is the result of collaborative work involving researchers in materials theory (Professor Olle Eriksson), physical materials synthesis (Professor Björgvin Hjörvarsson), and experimental physics.

These findings are important for our ability to analyze the magnetic properties of a material using equipment that is standard in most electron microscopy laboratories today.

“The technology will also enhance our knowledge of the energy losses that occur in magnetic components in generators and transformers,” says Klaus Leifer.

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Journal reference:

1. Hans Lidbaum, Ján Rusz, Andreas Liebig, Björgvin Hjörvarsson, Peter M. Oppeneer, Ernesto Coronel, Olle Eriksson, and Klaus Leifer. Quantitative Magnetic Information from Reciprocal Space Maps in Transmission Electron Microscopy. Physical Review Letters, 2009; 102 (3): 037201 DOI: 10.1103/PhysRevLett.102.037201

FEB 27,2009
Researchers at Purdue University have developed a technique using spun-sugar filaments to create a scaffold of tiny synthetic tubes that might serve as conduits to regenerate nerves severed in accidents or blood vessels damaged by disease.

The sugar filaments are coated with a corn-based degradable polymer, and then the sugar is dissolved in water, leaving behind bundles of hollow polymer tubes that mimic those found in nerves, said Riyi Shi, an associate professor in Purdue's Weldon School of Biomedical Engineering and Department of Basic Medical Sciences.

The scaffold could be used to promote nerve regeneration by acting as a bridge placed between the ends of severed nerves, said biomedical engineering doctoral student Jianming Li, who is a member of Shi's research team that developed the technique.

The researchers are initially concentrating on the peripheral nerves found in the limbs and throughout the body because nerve regeneration is more complex in the spinal cord. About 800,000 peripheral nerve injuries are reported annually in the United States, with about 50,000 requiring surgery.

The approach also might have applications in repairing blood vessels damaged by trauma and disease such as atherosclerosis and diabetes, Shi said.

The new approach represents a potential alternative to the conventional surgical treatment, which uses a nerve "autograft" taken from the leg or other part of the body to repair the injured nerves. Researchers are trying to develop artificial scaffolds to replace the autografts because removing the donor nerve causes a lack of sensation in the portion of the body where it was removed.

"The autograft is the lesser of two evils because you have to sacrifice a healthy nerve to repair a damaged segment," said Li, who led the research.

New findings were published online in December and this month in the print edition of the journal Langmuir. The paper was written by Li, biomedical engineering doctoral student Todd A. Rickett and Shi. Rickett also is attending the Indiana University School of Medicine in an MD-Ph.D. program.

Researchers from Cornell University published similar findings online Feb. 9 in the journal Soft Matter. Those findings focused on using the technique to create vascular networks for providing blood and nutrients to tissues and grafts.

The synthetic scaffold resembles the structural assembly of natural nerves, which are made of thousands of small tubes bundled together. These tubes act as sheaths that house the conducting elements of the nerve cell.

The first step in making the tubes is to spin sugar fibers from melted sucrose.

"It's basically like making cotton candy," Li said.

The sugar filaments were coated with a polymer called poly L-lactic acid. After the filaments were dissolved, hollow tubes of the polymer remained. The researchers then grew nerve-insulating cells called Schwann cells on these polymer tubes. These cells automatically aligned lengthwise along the tubes, as did nerve cells grown on top of the Schwann cells.

This alignment is critical for the fast growth of nerves, Shi said.

Nerve cells grew not only inside the hollow tubes but also around the outside of the tubes.

"This finding is important because the increased surface area may accelerate the regeneration process following an accident," Li said.

The scaffolds are designed specifically to regenerate a portion of a nerve cell called the axon, a long fiber attached to the cell body that transmits signals. Fast regeneration is essential to prevent the atrophy of muscles and organs connected to severed nerves.

The researchers also discovered that the polymer tubes contain pores that are ideal for supplying nutrients to growing nerve cells and removing waste products from the cells.

Images of the polymer-coated sugar strands were taken using a scanning electron microscope. Another instrument, called an atomic force microscope, was used to obtain images of the hollow tubes and pores in the walls of the tubules. Other images using fluorescent dyes revealed the nerve cell alignment along the tubes.

The work was done using cell cultures in petri dishes, but ongoing work focuses on implanting the scaffolds in animals.

The method for creating the scaffolds is relatively simple and inexpensive and does not require elaborate laboratory equipment, Shi said.

"This is low-tech," he said. "We used the same kind of sugar found in candy and a cheap polymer to make samples of these scaffolds for a few dollars. The process easily lends itself to mass production. It is a unique idea, and the simplicity and efficiency of this technology distinguish it from other approaches for nerve repair."

A provisional patent application on the material has been filed.

This study was conducted at Purdue's Center for Paralysis Research, which receives funding support from the state of Indiana. Shi's lab is supported by both the National Institutes of Health and the National Science Foundation. Li was supported by the NSF's Graduate Teaching Fellows in K-12 Education Program, which strives to help graduate students bring their research and practice into the K-12 classrooms and inspire students to pursue careers in science and engineering. Li used knowledge gained in the laboratory to teach middle school students and worked on curriculum development. Rickett is supported through the Indiana Clinical and Translational Sciences Institute, which funds research on developing new technologies into effective medical therapies.

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FEB 25,2009
A new facility opening later this year at the Diamond synchrotron is set to revolutionise world heritage science. A new research platform soon to be available at the leading UK science facility, Diamond Light Source, will help uncover ancient secrets that have been locked away for centuries. For the first time ever, cultural heritage scientists will be able to scan and image large relics and artifacts up to two tonnes in weight in incredible precision. They will no longer be restricted to examining small items.

Speaking at the AAAS Meeting in Chicago Dr Jen Hiller, Diamond's resident archaeologist, announced that the UK synchrotron will open a powerful new experimental station this autumn. Called the Joint Engineering, Environmental and Processing (JEEP) beamline, it will carry out experiments in a variety of areas including the growing field of world heritage science.

Dr Hiller explains, "Heritage scientists across the world are able to apply to use this unique beamline to delve deep inside precious ancient artifacts to unravel their secrets in a non-invasive way. Never before has it been possible to scan and image such large relics with such precision. Now is the time for researchers in this field to maximise this unique opportunity and consider how JEEP can help to advance their studies. "

"Thanks to the intensity of the X-rays produced by JEEP and its flexible space, researchers will be able to obtain a much higher resolution image, down to the scale of a few microns (less than the width of a human hair), and in significantly less time than the existing methods; we are talking about a matter of minutes as opposed to a number of hours. This finely detailed picture will enable scientists to see right inside an artifact helping them to obtain crucial information to piece together the story of its origin and history." continues Dr Hiller.

Eagerly awaiting the arrival of JEEP is Dr Janet Ambers, a scientist from the Conservation and Scientific Research Department at the British Museum. Along with her team Dr Ambers is currently studying a group of half life-sized Egyptian bronze statues. Until now they have only been able to examine them in a limited amount of detail leaving many questions unanswered. Diamond's JEEP beamline is set to change that.

Dr Ambers says, "We know that these statues are made up of a number of different parts that have been joined together. The joins are so dense that it is only by using JEEP's intense X-rays that we will be able to penetrate them and see how the statues were made. This will help to answer questions about the technology and materials used to originally produce the statues as well as provide information on how they were modified during 19th century restoration work. We are very excited about having access to this innovative tool because it will allow us to look at our artefacts in a completely new way."

Current analytical methods used by scientists at the British Museum allow them to produce standard 'X-rays' of objects using a static industrial X-ray tube. Alternatively, using a medical facility it is possible to perform a CT scan for relatively light objects. But both of these methods are limited in their precision and the amount of detail that they can provide. The former is incapable of creating a 3D image and the latter is suitable only for non-metallic objects. Neither method can deal with large heavy objects.

Dr Michael Drakopoulos, the Principal Beamline Scientist for JEEP, says, "The versatility of JEEP will open up exciting new opportunities in many fields of science due to its extremely high flux, high energy X-ray beam and its two complementary experimental areas. The larger area coming on line in Spring 2010, will be situated outside, further away from the X-ray source, allowing for a whole new range of exciting experiments currently not possible anywhere else in the world. It's fantastic that JEEP can help not only towards major advances in the environmental sciences and the world of engineering but also can have an extremely positive impact within the field of world heritage science."

Developments like JEEP are crucial to the growing field of heritage science in the UK. This was recently demonstrated by the creation of the Science and Heritage Programme, an £8 million five year research plan funded by the Arts and Humanities Research Council (AHRC) and Engineering and Physical Sciences Research Council (EPSRC) and supported by Research Councils UK. The programme takes forward recommendations made by the House of Lords Science and Technology Select Committee report on science and heritage of November 2006. This concluded that there was a compelling need for a comprehensive national strategy for heritage science. The vision of the Science and Heritage Programme is to increase knowledge and the resilience of our cultural heritage in the face of twenty-first-century challenges.

Combined with techniques available at other complementary facilities, cultural heritage research carried out at the Diamond synchrotron and the advances in the tools it provides will help the UK to maintain its position as one of the world leaders in the field of world heritage science.

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FEB 25,2009
Graphene, a single-atom-thick sheet of carbon, holds remarkable promise for future nanoelectronics applications. Whether graphene actually cuts it in industry, however, depends upon how graphene is cut, say researchers at the University of Illinois.

Graphene consists of a hexagonal lattice of carbon atoms. While scientists have predicted that the orientation of atoms along the edges of the lattice would affect the material's electronic properties, the prediction had not been proven experimentally.

Now, researchers at the U. of I. say they have proof.

"Our experimental results show, without a doubt, that the crystallographic orientation of the graphene edges significantly influences the electronic properties," said Joseph Lyding, a professor electrical and computer engineering. "To utilize nanometer-size pieces of graphene in future nanoelectronics, atomically precise control of the geometry of these structures will be required."

Lyding and graduate student Kyle Ritter (now at Micron Technology Inc. in Boise, Idaho) report their findings in a paper accepted for publication in Nature Materials online Feb. 15.

To carry out their work, the researchers developed a method for cutting and depositing nanometer-size bits of graphene on atomically clean semiconductor surfaces like silicon.

Then they used a scanning tunneling microscope to probe the electronic structure of the graphene with atomic-scale resolution.

"From this emerged a clear picture that edges with so-called zigzag orientation exhibited a strong edge state, whereas edges with armchair orientation did not," said Lyding, who also is affiliated with the university's Beckman Institute and the Micro and Nanotechnology Laboratory.

"We found that pieces of graphene smaller than about 10 nanometers with predominately zigzag edges exhibited metallic behavior rather than the semiconducting behavior expected from size alone," Lyding said. "This has major implications in that semiconducting behavior is mandatory for transistor fabrication."

Unlike carbon nanotubes, graphene is a flat sheet, and therefore compatible with conventional fabrication processes used by today's chipmakers. But, based on the researchers' experimental results, controlled engineering of the graphene edge structure will be required for obtaining uniform performance among graphene-based nanoelectronic devices.

"Even a tiny section of zigzag orientation on a 5-nanometer piece of graphene will change the material from a semiconductor into a metal," Lyding said. "And a transistor based on that, will not work. Period."

The Office of Naval Research and the National Science Foundation funded the work.

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Journal reference:

1. Kyle A. Ritter, Joseph W. Lyding. The influence of edge structure on the electronic properties of graphene quantum dots and nanoribbons. Nature Materials, 2009; 8 (3): 235 DOI: 10.1038/nmat2378

FEB 17,2009
Tomorrow's fuel-cell vehicles may be powered by enzymes that consume cellulose from woodchips or grass and exhale hydrogen.

Researchers at Virginia Tech, Oak Ridge National Laboratory (ORNL), and the University of Georgia have produced hydrogen gas pure enough to power a fuel cell by mixing 14 enzymes, one coenzyme, cellulosic materials from nonfood sources, and water heated to about 90 degrees (32 degrees Celsius).

The group announced three advances from their "one pot" process: 1) a novel combination of enzymes, 2) an increased hydrogen generation rate -- to as fast as natural hydrogen fermentation, and 3) a chemical energy output greater than the chemical energy stored in sugars – the highest hydrogen yield reported from cellulosic materials. "In addition to converting the chemical energy from the sugar, the process also converts the low-temperature thermal energy into high-quality hydrogen energy – like Prometheus stealing fire," said Percival Zhang, assistant professor of biological systems engineering in the College of Agriculture and Life Sciences at Virginia Tech.

"It is exciting because using cellulose instead of starch expands the renewable resource for producing hydrogen to include biomass," said Jonathan Mielenz, leader of the Bioconversion Science and Technology Group at ORNL.

The researchers used cellulosic materials isolated from wood chips, but crop waste or switchgrass could also be used. "If a small fraction – 2 or 3 percent – of yearly biomass production were used for sugar-to-hydrogen fuel cells for transportation, we could reach transportation fuel independence," Zhang said. (He added that the 3 percent figure is for global transportation needs. The U.S. would actually need to convert about 10 percent of biomass – which would be 1.3 billion tons of usable biomass).

The research is supported by the Air Force Office of Scientific Research; Zhang's DuPont Young Professor Award, and the U.S. Department of Energy.

Courtesy: www.sciencedaily.com

Scientists in Arizona and New Jersey are reporting that aerogels, a super-lightweight solid sometimes called “frozen smoke,” may serve as the ultimate sponge for capturing oil from wastewater and effectively soaking up environmental oil spills.

In the new study, Robert Pfeffer and colleagues point out that the environmental challenges of oil contamination go beyond widely publicized maritime oil spills like the Exxon Valdez incident.

Experts estimate that each year people dump more than 200 million gallons of used oil into sewers, streams, and backyards, resulting in polluted wastewater that is difficult to treat. Although there are many different sorbent materials for removing used oil, such as activated carbon, they are often costly and inefficient. Hydrophobic silica aerogels are highly porous and absorbent material, and seemed like an excellent oil sponge.

The scientists packed a batch of tiny aerogel beads into a vertical column and exposed them to flowing water containing soybean oil to simulate the filtration process at a wastewater treatment plant. They showed that the aerogel beads absorbed up to 7 times their weight and removed oil from the wastewater at high efficiency, better than many conventional sorbent materials.

FEB 16,2009
MIT researchers who study the structure of protein-based materials with the aim of learning the key to their lightweight and robust strength have discovered that the particular arrangement of proteins that produces the sturdiest product is not the arrangement with the most built-in redundancy or the most complicated pattern.

Instead, the optimal arrangement of proteins in the rope-like structures they studied is a repeated pattern of two stacks of four bundled alpha-helical proteins.

This composition of two repeated hierarchies (stacks and bundles) provides great strength—the ability to withstand mechanical pressure without giving way—and great robustness—the ability to perform mechanically, even if flawed. Because the alpha-helical protein serves as the building block of many common materials, understanding the properties of those materials has been the subject of intense scientific inquiry since the protein's discovery in the 1940s.

In a paper published in the Jan. 27 online issue of Nanotechnology, Markus Buehler and Theodor Ackbarow describe a model of the protein’s performance, based on molecular dynamics simulations. With their model they tested the strength and robustness of four different combinations of eight alpha-helical proteins: a single stack of eight proteins, two stacks of four bundled proteins, four stacks of two bundled proteins, and double stacks of two bundled proteins. Their molecular models replicate realistic molecular behavior, including hydrogen bond formation in the coiled spring-like alpha-helical proteins.

“The traditional way of designing materials is to consider properties at the macro level, but a more efficient way of materials’ design is to play with the structural makeup at the nanoscale,” said Buehler, the Esther and Harold E. Assistant Professor in the Department of Civil and Environmental Engineering. “This provides a new paradigm in engineering that enables us to design a new class of materials.”

More and more frequently, natural protein materials are being used as inspiration for the design of synthetic materials that are based on nanowires and carbon nanotubes, which can be made to be much stronger than biological materials. Buehler and Ackbarow's work demonstrates that by rearranging the same number of nanoscale elements into hierarchies, the performance of a material can be radically changed. This could eliminate the need to invent new materials for different applications.

In a follow-up study, Buehler and CEE graduate students Zhao Qin and Steve Cranford ran similar tests using more than 16,000 elements instead of eight. They found that 98 percent of the randomly arranged rope-like structures did not meet the optimal performance level of the self-assembled natural molecules, which made up the other 2 percent of the structures. The most successful of those again utilized the bundles of four alpha-helical proteins.

That analysis shows that random arrangements of elements typically lead to inferior performance, and may explain why many engineered materials are not yet capable of combining disparate properties such as robustness and strength.

“Only a few specific nanostructured arrangements provide the basis for optimal material performance, and this must be incorporated in the material design process,” said Buehler.

This work is funded by the Army Research Office, a National Science Foundation CAREER Award, and the Air Force Office of Scientific Research. Ackbarow, a graduate student at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, was supported in this work by the German National Academic Foundation, the Hamburg Foundation for research studies abroad and the Dr. Juergen Ulderup Foundation.

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FEB 4,2009
UV light-enhanced tooth bleaching is not only a con, but is dangerous to your eyes and skin, says a Royal Society of Chemistry journal.

The light treatment gives absolutely no benefit over bleaching without UV, and damages skin and eyes up to four times as much as sunbathing, reports a study in Photochemical & Photobiological Sciences.

Those looking to match Tom Cruise’s glittering pearly-whites would be better off ignoring claims of better bleaching with UV light treatment.

The treatment is at least as damaging to skin and eyes as sunbathing in Hyde Park for a midsummer’s afternoon – one lamp actually gave four times that level of radiation exposure.

And as with sunbathing, fair-skinned or light-sensitive people are at even greater risk, said lead author Ellen Bruzell of the Nordic Institute of Dental Materials.

Bruzell also found that bleaching damaged teeth. She saw more exposed grooves on the enamel surface of bleached teeth than on unbleached teeth. These grooves make the teeth more vulnerable to mechanical stress.

Tooth bleaching is one of the most popular cosmetic dental treatments available. It uses a bleaching agent – usually hydrogen peroxide – to remove stains such as those from red wine, tea and coffee, and smoking.

UV light is claimed to further activate the oxidation process, improving bleaching efficiency. The authors of this Photochemical & Photobiological Sciences article say there is very little substantive evidence to support this claim, and their new study finds no benefit to using UV light.

Courtesy: www.sciencedaily.com

FEB 23,2009
“One of the most important problems in materials science solved,” reports Professor Peter Oppeneer of Uppsala University. Together with three colleagues, he has managed to explain the hitherto unsolved riddle in materials science known as ‘the hidden order' - how a new phase arises and why.

This is a discovery that can be of great importance to our understanding of how new material properties occur, how they can be controlled and exploited in the future.

For a long time researchers have attempted to develop the superconducting materials of the future that will be able to conduct energy without energy losses, something of great importance to future energy production. But one piece of the puzzle has been missing. There are several materials that evince a clear phase shift in all thermodynamic properties when the temperature falls below a certain transitional temperature, but no one has been able to explain the new collective order in the material. Until now, it has been called the hidden order.

"The hidden order was discovered 24 years ago, and for all these years scientists have tried to find an explanation, but so far no one has succeeded. This has made the question one of the hottest quests in materials science. And now that we can explain how the hidden order in materials occurs, in a manner that has never been seen before, we have solved one of the most important problems of our day in this scientific field," says Professor Peter Oppeneer.

Four physicists from Uppsala University, led by Peter Oppeneer and in collaboration with John Mydosh from the University of Cologne, who discovered the hidden order 24 years ago, show through large-scale calculations how the hidden order occurs. Extremely small magnetic fluctuations prompt changes in the macroscopic properties of the material, so an entirely new phase arises, with different properties.

"Never before have we seen the so-called ‘magnetic spin excitations' produce a phase transition and the formation of a new phase. In ordinary material this excitation cannot change the phase and properties of the material because it is too weak. But now we have shown that this is in fact possible," says Peter Oppeneer.

What explains in detail all of the physical phenomena in the hidden order is a computer-based theory. Among other applications, it can be used to better understand high-temperature superconducting materials and will thus be important in the development of new superconducting materials and future energy production.

Courtesy: www.sciencedaily.com

New plastics may soon replace metals in auto bodies. Designers are beginning to discover a whole new world of possibilities offered by materials that can be bent into futuristic shapes.

DETROIT--Imaginations are let loose on car designs of the future. Now, young, creative minds are pushing automotive design to its limits, using every shape, color and size in their creations.

Designers and engineers who take their dreams and turn them into reality create these new cars of the future.

Chris Piscitelli's zest for cars started when he was just a kid. "My father is an old car enthusiast, so I grew up around it." Piscitelli is a design student at the College for Creative Studies in Detroit. As he got older, he learned his love of cars could be linked with his artistic talent.

"I have a passion for cars and design, so it was just natural for me to get into automotive design," Piscitelli says.

Now, Chris is part of a future generation of car designers learning to put new materials to use in exciting, futuristic ways. "We're supposed to stress the use of a lot of the new plastics and things that you do with plastics that you couldn't necessarily do with say, you know, steel," Piscitelli tells Ivanhoe.

Plastic is easy to mold so using materials engineering, Chris used the advantages of plastic by heating it so the long, spaghetti-like molecules slide over each other to form new shapes, giving us durable, cost-effective, lightweight plastics with sleek curves.

Jim Kolb, vice president of American Plastics Council in Troy says, "The limitations that some metals have in forming parts -- are overcome with the use of plastics."

Plastic concepts have caught the eye of car companies who see the future of car design in students like Piscitelli. "We're able to push the limit with the project, and so to make something that was, you know, kind of futuristic and, you know, out there, but also could be seen on the road," Piscitelli says. His concept car may not be road-ready right now, but it's a nice sneak peak at what the future holds.

Car manufacturers are working to make affordable plastic cars available to consumers.

New steel technologies are offering better looks, performance and protection for cars. To make new steel alloys, metallurgical engineers are mixing different kinds of metals like nickel, with iron to make a lighter, stronger, more-flexible automobile.

PITTSBURGH--High gas prices are forcing consumers to fork over fistfuls of cash at the pump. In fact, AAA says prices are now a dollar more than this time last year. Now, a new car technology might offer some relief when filling up your car at the pump.

Rising gas prices are hitting Andy Carson where it hurts -- his wallet. "I think gas prices are going to have a tremendous effect on my decision on what car I'm going to buy," Carson says. Fuel economy is playing a big part in his decision. Now, new high-tech materials for cars may produce a car to fit his budget.

Richard Fruehan, a metallurgical engineer from Carnegie Mellon University in Pittsburgh, says, "These very new steels have unique properties. This will enable us to use these steels in automobiles and reduce the weight of the automobiles and get the resulting fuel economy."

New steel technologies offer better looks, performance and protection for cars. Fruehan says, "The result will be a car that lasts longer, a car that gets better fuel economy and a car that is safe for the passenger." To make new steel materials, metallurgical engineers mix different kinds of metals, like nickel with iron to make a lighter, stronger, more-flexible product. "These steels are more coatable to resist corrosion, so the steels that we're pitting in are much better," Fruehan says.

Improved materials for cars could be the answer to gas mileage sticker-shock and give Andy Carson an upgrade. "I get good gas mileage now, but I think I can do a lot better," he says. But for now, he's paying the price at the pump and hopes for relief down the road.

If you think the United States prices are high, in Europe, they pay $7 a gallon. So experts say now is the time to tackle the problem.

Coutesy: www.sciencedaily.com

When moisture condenses on a cool surface, droplets can form that are the right size to scatter light, fogging up glass. A new polymer coating draws droplets into nanopores and transforms them into a transparent sheet, improving vision.

BOSTON--If you're all fogged up, a new discovery may have you seeing more clearly. Fog is not just a weather nuisance for drivers; it can cause problems just about everywhere. Now, a new anti-fog glass coating is clearing the way for consumers.

Your bathroom mirror, eyeglasses, and your car windshield all fall victim to fog. It can happen anywhere moisture condenses on a cool surface.

Michael Rubner, a materials chemist and professor of Polymer Material Science at Massachusetts Institute of Technology in Boston, says, "When they condense they are just the right size to scatter light. If light gets scattered you can't see through those glasses anymore."

Michael created a polymer coating, made from different materials that transform the opaque droplets of water into a transparent sheet. "All of the process that we use to create these coatings is done with water," he says.

The process begins by dipping the glass into a solution of negatively charged tiny glass particle. After, it's dipped into another solution with positively charged polymers. Michael says: "We're forming what we call nanopores. The pores are so small that you can't see them with your eyes. They don't scatter light. But they're large enough so that when you put a drop of water onto the surface, it's drawn into those pores and spread across the surface instantaneously."

The effect allows you to continue seeing clearly through the piece of coated glass. This not only helps you at home, but even the military is looking for fog-free glass. Thomas Long, from Fosta-Tek Optics in Leominster, Mass., says, "The soldiers are faced with either having a foggy field of vision or taking those glasses off to improve their vision, but then being vulnerable to fragments of shrapnel ending their eyesight."

Michael says his coating promises to be long lasting for soldiers out in the field and to drivers just trying to see their way home. He's trying to find a cost-effective way to mass market the polymer coating and hopes it will be available in the next few years.

Courtesy: www.sciencedaily.com

New materials for car bodies may soon transform the auto industry. Auto engineers can mold these carbon-fiber-reinforced plastics into virtually any shape. The materials are both strong and light -- increasing fuel efficiency and safety at the same time.

TROY, Mich.-- Cars built entirely out of plastic could be the wave of the future, making metal a thing of the past when it comes to cars.

New, innovative cars made almost entirely of plastic are paving the way for what you may be driving in the future. Guan Chew, a mechanical engineer at Porsche Engineering Services in Troy, Mich., says, "With plastics you can design cars which are very bold, and that gives you an advantage to sell nicer cars."

Plastics have gained a lot of ground over traditional metals used in cars, making it possible to build almost an entire vehicle completely of non-metal material. Paul Ritchie, CEO and engineer at Porsche Engineering Services, says: "The Carrera GT is what we would refer to as a proving ground for one of our new materials. It's made essentially from reinforced plastic."

Mechanical engineers use a lightweight, high-strength aerospace material called carbon-fiber-reinforced plastic. It's used in the doors, hoods, fenders, chasis and also in support frames for the engine and transmission.

"You can mold the plastics into very complicated shapes that maybe you can't do in steel," Chew says. Looks aren't the only perks of plastic; plastics help cars lose weight to go farther on fuel.

New materials, like plastic, are usually tested on high-end vehicles first. Once the materials are proven to be more efficient and cost effective, they eventually filter down to affordable consumer vehicles.

Transporting energy without any loss, travelling in magnetically levitated trains, carrying out medical imaging (MRI) with small-scale equipment: all these things could come true if we had superconducting materials that worked at room temperature. Researchers at CNRS have now taken another step forward on the road leading to this ultimate goal. They have revealed the metallic nature of a class of so-called critical high-temperature superconducting materials.

This result, which was published in the 31 May 2007 issue of the journal Nature, has been eagerly awaited for 20 years. It paves the way to an understanding of this phenomenon and makes it possible to contemplate its complete theoretical description.

Superconductivity is a state of matter characterized by zero electrical resistance and impermeability to a magnetic field. For instance, it is already used in medical imaging (MRI devices), and could find spectacular applications in the transport and storage of electrical energy without loss, the development of transport systems based on magnetic levitation, wireless communication and even quantum computers.

However, for now, such applications are limited by the fact that superconductivity only occurs at very low temperatures. In fact, it was only once a way of liquefying helium had been developed, which requires a temperature of 4.2 kelvins (-269 °C), that superconductivity was discovered, in 1911 (a discovery for which the Nobel Prize was awarded two years later.)

Since the end of the 1980s (Nobel Prize in 1987), researchers have managed to obtain 'high temperature' superconducting materials: some of these compounds can be made superconducting simply by using liquid nitrogen (77 K, or -196 °C). The record critical temperature (the phase transition temperature below which superconductivity occurs) is today 138 K (-135 °C).

This new class of superconductors, which are easier and cheaper to use, has given fresh impetus to the race to find ever higher critical temperatures, with the ultimate goal of obtaining materials which are superconducting at room temperature. However, until now, researchers have been held back by some fundamental questions. What causes superconductivity at microscopic scales" How do electrons behave in such materials"

Researchers at the National Laboratory for Pulsed Magnetic Fields2, working together with researchers at Sherbrooke, have observed 'quantum oscillations', thanks to their experience in working with intense magnetic fields. They subjected their samples to a magnetic field of as much as 62 teslas (a million times stronger than the Earth's magnetic field), at very low temperatures (between 1.5 K and 4.2 K).

The magnetic field destroys the superconducting state, and the sample, now in a normal state, shows an oscillation of its electrical resistance as a function of the magnetic field. Such an oscillation is characteristic of metals: it means that, in the samples that were studied, the electrons behaved in the same way as in ordinary metals.

The researchers will be able to use this discovery, which has been eagerly awaited for 20 years, to improve their understanding of critical high-temperature superconductivity, which until now had resisted all attempts at modeling it. The discovery has been effective in sorting out the many theories which had emerged to explain the phenomenon, and provides a firm foundation on which to build a new theory. It will make it possible to design more efficient materials, with critical temperatures closer to room temperature.

Reference: Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor, Nicolas Doiron-Leyraud, Cyril Proust, David LeBoeuf, Julien Levallois, Jean-Baptiste Bonnemaison, Ruixing Liang, D. A. Bonn, W. N. Hardy, Louis Taillefer, Nature, 31 May 2007, Vol 447, pp 565-568.