Researchers develop new hydrogen storage technology

February 14, 2011 (PhysOrg.com) -- Working with scientists from the STFC’s Rutherford Appleton Laboratory and the University of Oxford, LCN researchers Zeynep Kurban and Professor Neal Skipper and UCL graduate Dr Arthur Lovell have developed a new technology that allows hydrogen to be stored in a cheap and practical way, making it promising for widespread use as a carbon-free alternative to petrol.

The team have developed a new nano-structuring technique called ‘co-electrospinning’ to produce tiny plastic micro-fibres 30 times smaller than a human hair. These hollow micro-fibres have then been used to encapsulate hydrogen-rich chemicals known as hydrides, in a way that allows the hydrogen to be released at much faster rates and at lower temperatures than was previously possible. The encapsulation also protects the hydrides from oxygen and water, prolonging their life and making it possible to handle them safely in air.

This new nano-material contains as much hydrogen for a given weight as the high pressure tanks currently used in prototype hydrogen vehicles, and can also be made in the form of micro beads that can be poured and pumped like a liquid. These properties mean that the beads could be used to fill up tanks in cars and aeroplanes in a very similar way to current fuels, but crucially without producing the carbon emissions. This technology underpins the new spin-out company Cella Energy Ltd, which is based at the Harwell Science and Innovation Campus, Oxfordshire.

UCL doctoral student Zeynep Kurban (pictured), who played a key role in the scientific development while studying for her EngD in Molecular Modeling and Materials Science, said: “This new technology provides solutions to some of the key issues surrounding hydrogen storage systems, bringing us a step closer to commercialisation of these materials for clean energy applications.”

The lead A round investor in Cella Energy is Thomas Swan & Co. Ltd., a specialist UK chemical company established in 1926. Thomas Swan’s Advanced Materials Division is dedicated to the development of high specification materials for emerging technologies with particular focus on carbon nanomaterials and advanced coatings. Shareholders also include STFC Innovations Ltd, UCL Business PLC and the Chancellor, Masters and Scholars of the University of Oxford.

Dr Tim Fishlock, Business Manager at UCL Business said: “Cella Energy is capitalising on an innovative technology developed within the research labs of three world class research centres at RAL, UCL and Oxford, which brings the large scale adoption of hydrogen powered vehicles closer to reality. Thomas Swan & Co is a fantastic partner for Cella Energy and wish the team every success with their future plans.”

More information: Academic paper: A Solution Selection Model for Coaxial Electrospinning and its Application to Nanostructured Hydrogen Storage Materials

Researchers study flu proteins in-depth to identify virus vulnerabilities

Mei Hong, a chemist at Iowa State University, uses NMR to study a proton channel named M2, found on the surface of the influenza virus. This proton channel has been the subject of numerous studies because of the key role it plays in helping a virus take over a healthy cell after it gets inside.

In order to infect a healthy cell, a flu virus must enter the cell and empty viral genes into it. First, the virus binds to the cell. Then it becomes enveloped inside a bubble called an endosome as it gets taken into the cell. It is acidic inside the endosome--more acidic than the interior of the virus it contains. This pH difference serves as a signal to the virus that it is inside the cell, so it is time to release the viral genes. It is the M2 proton channel that helps the virus sense this difference in acidity and trigger the release of viral genes into the cell. Since the cell cannot tell the difference between its own genes and those of the virus, it gets tricked into making copies of the virus which can eventually go on to infect other cells.

Another great unknown

We know quite a bit about how a virus can infect a cell, but until recently it was still unclear exactly how the protons move from the endosome into the virus to trigger infection. Scientists suggested two distinct possibilities: the first, a "shutter" model in which the channel is either "open" or "closed" to the flow of water that carries an extra proton into the virus, or a "shuttle" model, in which the components of the channel actually move to relay protons from the exterior to the interior of the virus.

"Computational methods for predicting these structures are not good enough yet, so experimentally determining the high resolution structure of the histidine portion of this molecule, which controls the proton relay, is very important. Fortunately we had a vast knowledge of this protein that allowed us to zoom in on the histidine residue precisely," said Hong.

The role of NMR

But what is NMR, and how do researchers use it? NMR is actually a property of the nucleus of an atom when it interacts with a magnetic field. What that means is that NMR is a property of matter, like color or density or mass. Scientists have found ways to turn this property into useful information, especially in the field of imaging. For example, physicians use magnetic resonance imaging (MRI) machines to see inside a patient without surgery. These machines use NMR to create a detailed visualization of tissues in the body. Scientists can use NMR in the same way on a really magnified scale to look inside much smaller things like an individual protein, or even just a part of a protein.

"One can study the structure of proteins in many ways, but protons are difficult to visualize by X-rays," said Hong. X-rays are commonly used to study the structure of proteins in a crystal form. "We used NMR because we wanted to see where the protons are relative to the channel. Moreover, the state of the samples that we study using NMR is closer to the natural biological state than most other structure determination techniques."

Shuttling through

Using NMR, Hong's team was able to obtain evidence that the channel moves protons by the "shuttle" model. The work, published in the October 22, 2010 issue of the journal Science, shows that ring-shaped histidine molecules facing the pore of the channel are able to flip back and forth at more than 50,000 times per second when the channel is in an open state (imagine a windshield wiper-like motion).

After every few flips, the histidine is able to pick up a proton from outside the virus and flip it into the interior of the virus. Movement of protons into the virus causes the interior to become more acidic as protons accumulate. This serves as a signal that the virus is inside the cell, and it should release its genes--the next step in the viral infection process.

It's a shuttle. So what?

Knowing which model is the right one is actually pretty important, because there are drugs that can block this step in the process of viral infection. Amantadine and rimantadine, respectively known by the trade names Symmetrel and Flumadine, are two of the older antiviral drugs approved by the FDA. Both have been shown to make flu symptoms less severe and shorten the time it takes to get better.

Hong has also used NMR to learn more about amantadine, which prevents susceptible viruses from spreading. The study, included in Nature on February 4, 2010, showed that amantadine binds two different sites on the M2 protein. Combined with other data, Hong and colleagues concluded that amantadine physically blocks the M2 channel, preventing the movement of protons into the virus and subsequently, reproduction and spread of the virus.

Unfortunately, amantadine and rimantadine are no longer recommended for widespread use because many flu strains, including H1N1, are resistant.

Bring on the mutants

Now that scientists have a better understanding of how the M2 channel moves protons and where amantadine binds in the M2 channel, they want to use the same techniques to study how the M2 channel is different in drug-resistant versions of the virus.

Hong explained, "Since most flu viruses now have the mutation, we will focus on that next."

Results from the Nature paper hint that amantadine did not fit well into the M2 channel. One strategy could be to design a drug that is better able to occupy the known binding sites, but now that we know the channel must "shuttle" the protons through, Hong says there are more options: "Targeting the histidine may work just as well to block the channel."

New and better antiviral drugs will aid those that didn't get vaccinated, or those that become ill before their vaccine becomes fully effective. Millions of people in the United States get the flu each year. The majority will recover without treatment, but thousands become sick enough to be hospitalized. According to CDC estimates, there are anywhere from 3,000 to 49,000 flu-related deaths each year. Effective drug treatment could prevent hospitalizations and reduce the number of complication-related deaths.

Fighting disease in the future

Research in this area will provide benefits beyond development of better antiviral drugs. Eventually, scientists will have enough data from NMR experiments to work with mathematicians on creating models that can more accurately predict the shape and structure a protein will have. These models, once tested and refined, could help researchers predict and identify previously unknown molecular interactions. A better understanding of the myriad of players that interact to make us feel good or bad each day could play a significant role in shaping future medical diagnostics and treatments. Studies that allow increasingly accurate unification of protein structure and function, like the NMR experiments done by Mei Hong, are steps on the path towards more effective, personalized medical treatments.

New plastics can conduct electricity

 

(PhysOrg.com) -- A newly discovered technique makes it possible to create a whole new array of plastics with metallic or even superconducting properties.

Plastics usually conduct electricity so poorly that they are used to insulate electric cables but, by placing a thin film of metal onto a plastic sheet and mixing it into the polymer surface with an ion beam, Australian researchers have shown that the method can be used to make cheap, strong, flexible and conductive plastic films.

The research has been published in the journal ChemPhysChem by a team led by Professor Paul Meredith and Associate Professor Ben Powell, both at the University of Queensland, and Associate Professor Adam Micolich of the UNSW School of Physics. This latest discovery reports experiments by former UQ Ph.D. student, Dr Andrew Stephenson.

Ion beam techniques are widely used in the microelectronics industry to tailor the conductivity of semiconductors such as silicon, but attempts to adapt this process to plastic films have been made since the 1980s with only limited success – until now.

"What the team has been able to do here is use an ion beam to tune the properties of a plastic film so that it conducts electricity like the metals used in the electrical wires themselves, and even to act as a superconductor and pass electric current without resistance if cooled to low enough temperature," says Professor Meredith.

To demonstrate a potential application of this new material, the team produced electrical resistance thermometers that meet industrial standards. Tested against an industry standard platinum resistance thermometer, it had comparable or even superior accuracy.

"This material is so interesting because we can take all the desirable aspects of polymers - such as mechanical flexibility, robustness and low cost - and into the mix add good electrical conductivity, something not normally associated with plastics," says Professor Micolich. "It opens new avenues to making plastic electronics."

Andrew Stephenson says the most exciting part about the discovery is how precisely the film’s ability to conduct or resist the flow of electrical current can be tuned. It opens up a very broad potential for useful applications.

"In fact, we can vary the electrical resistivity over 10 orders of magnitude – put simply, that means we have ten billion options to adjust the recipe when we're making the plastic film. In theory, we can make plastics that conduct no electricity at all or as well as metals do – and everything in between,” Dr Stephenson says.

These new materials can be easily produced with equipment commonly used in the microelectronics industry and are vastly more tolerant of exposure to oxygen compared to standard semiconducting polymers.

Combined, these advantages may give ion beam processed polymer films a bright future in the on-going development of soft materials for plastic electronics applications – a fusion between current and next generation technology, the researchers say.

Provided by University of New South Wales (news : web)

 

Residual dipolar couplings unveil structure of small molecules

 German chemists at the Technische Universitaet Muenchen and the Karlsruhe Institute of Technology introduced a new method for identifying chemical compounds. The approach they used is an improvement on nuclear magnetic resonance measurements -- for decades one of the most successful methods for determining the chemical structure of organic molecules. The results now published in the scientific journal Angewandte Chemie show a handy approach to structural data when classical methods of analysis fail.

The team of Professor Burkhard Luy from KIT and Junior Professor Stefan F. Kirsch from the TUM has now shown for the first time that certain NMR parameters, the so-called residual dipolar couplings (RDCs), can make a significant contribution towards determining the constitution of chemical compounds when traditional methods fail. To do this they embedded molecules of the compound in a gel which slightly constricts their mobility. By stretching the gel, the molecules can be aligned along a preferred orientation. While residual dipolar couplings average out in solution, they become measurable in such partially aligned samples and provide valuable structural information that can be used to build a model of the molecule.

To test this new approach to chemical structure determination the scientists examined a molecule whose atomic composition was known, but not the precise connectivities of the individual atoms in the molecule. The molecule was obtained using a unique reaction, so there were no precedents for its structure. Classical methods of analysis failed because of the compactness of the molecule. In this particular case it was only possible to determine the structure by means of residual dipolar couplings, so that the newly acquired knowledge could be used to draw conclusions about the formation of the molecule – something that in the past could only be speculated about.

"This type of analysis will not be suitable for all structures in the future," said scientists Luy and Kirsch. "There will still be molecules whose structures will defy all attempts at unraveling, in spite of tremendous efforts and cutting-edge technologies. But this new method provides us with one further tool to help us unravel the structural mysteries of nature."

More information: Grit Kummerlöwe, Benedikt Crone; Manuel Kretschmer, Stefan F. Kirsch und Burkhard Luy: Residual Dipolar Couplings as a Powerful Tool for Constitutional Analysis: The Unexpected Formation of Tricyclic Compounds. Angewandte Chemie International Edition, scheduled to go online 17 or 18 February 2011. DOI:10.1002/anie.2010007305

Provided by Technische Universitaet Muenchen

Researchers discover a new class of magic atomic clusters called superhalogens

February 11, 2011 This image illustrates MnxCl2x+1clusters - new class of magnetic superhalogens.The violet and green spheres represent Mn and Cl atoms, respectively. Image courtesy of Puru Jena, Ph.D./VCU, and Anil Kandalam, Ph.D./McNeese State University.

(PhysOrg.com) -- An international team of researchers has discovered a new class of magnetic superhalogens – a class of atomic clusters able to exhibit unusual stability at a specific size and composition, which may be used to advance materials science by allowing scientists to create a new class of salts with magnetic and super-oxidizing properties not previously found.

The discovery, which was published Feb. 10 in the Early View issue of the international chemistry journal Angewandte Chemie International Edition, was based on theoretical work by researchers from Virginia Commonwealth University, McNeese State University, and Peking University in China, and experimental work at Johns Hopkins University.

Unlike conventional superhalogens that are composed of a metal atom at the core and surrounded by halogen atoms, the magnetic superhalogens discovered by this team are composed of stoichiometric metal-halogen moieties at the core to which an additional halogen is attached.

The new chemical species known as magnetic superhalogens mimic the chemistry of halogens which are a class of elements from the periodic table, namely, iodine, astatine, bromine, fluorine and chlorine. The word halogen means "salt-former," and when one of the elements above combines with sodium, they can form a salt.

Specifically, the cluster is MnxCl2x+1, where x = 1, 2, 3, and so on, have manganese and chlorine atoms as a core to which only one chlorine atom is attached. The manganese atoms carry a large magnetic moment and therefore make these superhalogens magnetic.

"One can now design and synthesize yet unknown magnetic superhalogens by changing the metal atom from manganese to other transition metal atoms and changing chlorine to other halogen atoms. In addition to their use as oxidizing agents, being magnetic opens the door to the synthesis a new class of salts," said lead investigator Puru Jena, Ph.D., distinguished professor of physics at VCU.

According to Jena, superhalogens are like halogens, in the sense they form negative ions, but their affinity to attract electrons is far greater than those of any halogen atoms. Negative ions are useful as oxidizing agents, for purification of air and in serotonin release for uplifting mood.

"Superhalogens can do the same thing as halogens can do, only better," said Jena. "The ability of superhalogens to carry large quantities of fluorine and chlorine can be used for combating biological agents as well."

"In addition, superhalogens, due to their large electron affinity, can involve inner core electrons of metal atoms in chemical reaction, thus fundamentally giving rise to new chemistry," said Jena.

In October, Jena and his colleagues reported the discovery of a new class of highly electronegative chemical species called hyperhalogens, which use superhalogens as building blocks around a metal atom. The chemical species may have application in many industries.

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Science review casts doubt on 2001 anthrax case (Update 2)

There was insufficient scientific evidence to support the FBI's assertion that anthrax sent to politicians and journalists in the wake of the September 11 attacks originated in Ivins' lab, said the National Academy of Sciences.

"It is not possible to reach a definitive conclusion about the origins of the B. anthracis in the mailings based on the available scientific evidence alone," said the NAS report.

The anthrax mailings, which killed five people and injured 17, rattled an already jittery American public just days after Al-Qaeda militants hijacked passenger jets and plunged them into the World Trade Center and the Pentagon.

The review found that anthrax contained in a flask, known as RMR-1029, in Ivins' lab shared genetic similarities with spores in the mailed letters but "was not the immediate source of spores used in the letters."

"One or more derivative growth steps would have been required to produce the anthrax in the attack letters," the report said, adding that the letters sent to Washington had different characteristics than those sent to New York.

"They have enough physical and chemical differences between the two that they must have come from separate batches," said lead author of the report Alice Gast.

The FBI concluded that the mailed anthrax must have come from a single flask of parent spores that Ivins had created and which he alone had maintained.

The type of anthrax contained in the letters, mailed to NBC anchor Tom Brokaw, the New York Post and senators Tom Daschle and Patrick Leahy, was correctly identified as the Ames strain of B. anthracis, which originated from a cow in Texas in 1981 and was shared with labs worldwide, the report said.

But a key problem arose from the way the FBI attempted to narrow down the source of the anthrax by creating a repository of potential samples provided by the labs that maintain them.

The repository was incomplete, leaving the possibility that other sources could remain unexamined, and also relied on scientists to provide their own samples, allowing for manipulation by potential suspects.

"Standards of custody of evidence would dictate that agents of the FBI should have obtained the samples," the report said.

"The sender could have been the instigator and may not have complied with instructions, as the FBI alleges with respect to Dr. Ivins."

Ivins, a bio-defense researcher at the US Army's Medical Research Institute of Infectious Diseases, committed suicide by taking drugstore medications in July 2008 as FBI agents were about to bring charges against him.

Investigators began focusing on Ivins in 2007 after new forensic scientific methods traced the anthrax back to him.

The NAS report was delayed in November 2010 when the FBI, which had just received the final draft for security review, decided to release more, previously classified information for the panel to consider.

FBI investigators had looked at anthrax evidence from "an undisclosed overseas site at which a terrorist group's anthrax program was allegedly located," the report said.

"The information indicates that there was inconsistent evidence of Ames strain DNA in some of these samples, but no culturable B. anthracis," it said, adding that the late-arriving information "deserves a more thorough scientific review."

The NAS reviewers also noted that their analysis of evidence was limited to "the biological, physical, and chemical sciences," and did not consider other traditional forensic science methods.

The FBI, which commissioned the NAS report, highlighted the panel's assertion that a definitive conclusion based on science alone "was not possible" and said a combination of factors led investigators to Ivins.

"The FBI has long maintained that while science played a significant role, it was the totality of the investigative process that determined the outcome of the anthrax case," it said in a statement.

Some lawmakers called for a new, independent probe of the government's response.

"The National Academy of Sciences report released today shows that the science is not necessarily a slam dunk," said Senator Chuck Grassley.

"There are no more excuses for avoiding an independent review and assessment of how the FBI handled its investigation in the anthrax case."

Congressman Rush Holt said he was re-introducing a 2008 bill to establish a legislative commission to investigate.

Scientists find a new way insulin-producing cells die

The death of insulin-producing beta cells in the pancreas is a core defect in diabetes. Scientists in Italy and Texas now have discovered a new way that these cells die — by toxic imbalance of a molecule secreted by other pancreatic cells.

"Our study shows that neighboring cells called alpha cells can behave like adversaries for beta cells. This was an unexpected finding," said Franco Folli, M.D., Ph.D., professor of medicine/diabetes at The University of Texas Health Science Center at San Antonio. He is co-lead author on the study with Carla Perego, Ph.D., assistant professor of physiology at the University of Milan.

Balance needed to control sugars

Alpha and beta cells are grouped in areas of the pancreas called the islets of Langerhans. Alpha cells make glucagon, the hormone that raises blood sugar during fasting. In the same environment the beta cells make insulin, the hormone that lowers sugars after a meal. Imbalance ultimately leads to diabetes.

"We found that glutamate, a major signaling molecule in the brain and pancreas, is secreted together with glucagon by alpha cells and affects beta cell integrity," Dr. Folli said. "In a situation where there is an imbalance toward more alpha cells and fewer beta cells, as in Type 1 and Type 2 diabetes, this could result in further beta cell destruction."

Role of alpha cells

Glutamate toxicity is a new mechanism of beta cell destruction not previously known, Drs. Perego and Folli said. It has not been typically thought that alpha cells could themselves be a cause of beta cell damage, they said.

The study also found a protection for beta cells, namely, a protein called GLT1 that controls glutamate levels outside the beta cells. "GLT1 is like a thermostat controlling the microenvironment of beta cells with respect to glutamate concentration," Dr. Perego said.

Early warning

A diagnostic test for glutamate toxicity in the islets of Langerhans is being developed by the authors, Dr. Folli said. Eventually an intervention to slow the process could follow.

Glutamate poisoning is a new candidate mechanism for beta cell destruction in diabetes. Others are high glucose, buildup of a protein called amyloid, and free fatty acids, which are found in patients with type 2 diabetes.

"The vicious cycle in diabetes is that there are several substances that have been shown, also by us, to be toxic to beta cells," Dr. Folli said. "And now we have found a new one, glutamate."

More information: The Journal of Biological Chemistry published the study online this week.

Provided by University of Texas Health Science Center at San Antonio

Alchemy is making a comeback.

Chemistry / Other

Feb 24, 2011 | 4.8 / 5 (10) | 7 |

(PhysOrg.com) -- A newly discovered technique makes it possible to create a whole new array of plastics with metallic or even superconducting properties.

Chemistry / Materials Science

Feb 22, 2011 | 4.8 / 5 (34) | 1 |

Ordinary table sugar could be a key ingredient to developing much lighter, faster, cheaper, denser and more robust computer electronics for use on U.S. military aircraft.

Chemistry / Materials Science

Feb 25, 2011 | 4.7 / 5 (3) | 0 |

Most people would never suspect that a "trash tree," one with little economic value and often removed by farmers due to its ability to destroy farmland, could be the key to fighting a deadly bacterium. Now, ...

Chemistry / Biochemistry

Feb 22, 2011 | 4.9 / 5 (16) | 0 |

The number of connections between nerve cells in the brain can be regulated by an immune system molecule, according to a new study from UC Davis. The research, published Feb. 27 in the journal Nature Neuroscience, reveal ...

(AP) -- The astronauts aboard the orbiting shuttle-station complex geared up Sunday for the first spacewalk of their mission, amid some good news from Mission Control.

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Taiwan is to relax controls on investments from mainland China in the island's high-tech companies, a senior economic official said Sunday.

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