Thursday, February 16, 2012

New uses for diesel by-products

More sustainable production of sulphur-free diesel from natural gas and biomass is increasing. However the by-products, hydrocarbons like decane and other low value alkanes have little practical use.

Now a discovery by the Institute, part of the School of Chemistry, has found a potential route for upgrading these by-products into more useful chemicals.

In the past, synthetic reactions starting from alkanes like decane have been fraught with difficulty. They tend either to over-dehydrogenate or to combust, depending on whether oxygen is present in the reaction. Now a Cardiff Institute team has reported the use of a mixed-metal catalyst to convert decane to a range of oxygenated aromatics.

The breakthrough, published in Nature Chemistry, came when the team fed a of decane and air through an iron molybdate catalyst. At higher temperatures, the reaction formed water and decene, which is used in the production of detergents. At lower temperatures, however, the reaction took a different route to create oxygenated . These included phthalic anhydride, used in the dyeing industry, and which helps in the production of anti-coagulant drugs.

Professor Stan Golunski, a member of the Institute team behind the discovery said: "This discovery breaks new ground as it implies the involvement of oxygen that has not yet made the full transition from its molecular form to its ionic form. This overturns a widely-held view that this type of oxygen was too reactive to form anything other than carbon monoxide and carbon dioxide in reactions with hydrocarbons."

"While the increased production of sulphur-free diesel has been a positive move, the glut of low value by-products will become a problem. We hope our new process will lead to less waste and the creation of more useful chemicals for a range of industries."

Provided by Cardiff University (news : web)

Researchers discover the processes leading to acute myeloid leukemia

The UCSB research team described how a certain mutation in DNA disrupts in patients with (AML). The researchers were prompted to study this process by another research team's discovery that have a mutation in a certain , which was reported in the . The enzyme is a protein called DNMT3A, which leads to changes in how the DNA of AML patients is methylated, or "tagged." Norbert Reich, professor in the Department of Chemistry and at UCSB, was already studying that particular enzyme with his research group, so they began to study the disease process of AML at the cellular level.

Reich explained that tagging is a way of reading DNA at the . This falls within an area of study called epigenetics, a process that occurs "on top" of genetics. Each person has approximately 200 types of , all with the same DNA, and these must be controlled in different ways. "There is an enzyme –– a protein –– that tags DNA and controls which of the genes in your cells, your DNA, gets turned on and off," said Reich. "So you have 20,000 genes, and you have to control them differently in your brain than in your liver."

Reich explained that there is current interest in this broader field of epigenetics as a direction for the treatment of . "There's definitely the idea that this may be a new way of developing therapeutics, because you don't have to kill the cancer cell," said Reich. "Almost every that's out there works on the principle that a cancer cell needs to be killed."

In this artist's conception, the four-protein complex called DNMT3A is shown in its normal configuration (top left). The complex reads or "tags" the cell's DNA. In the upper right side of the image, several of these tags are shown on top of the double helix of DNA. The tags control which genes in a cell get turned on and off. In the bottom left image, the complex of four proteins is disrupted. This disruption is caused by the mutation found in patients with acute myeloid leukemia. In the right side of the bottom image, the protein leaves only one tag on the DNA and then moves on. Credit: Norbert Reich, UCSB

With epigenetics, instead of only having DNA sequence coding for certain genes, there is an epigenetic process, with another layer of information on top of the genetic process. In this case, that information is the tagging by the methyl groups.

"If you really think about it, this is part of the answer as to how your cells can be so different and yet they all have the same DNA," said Reich. "You have the same genome in every one of your cells, but you do not have the same epigenome, which is basically the methylation pattern, the tagging pattern. That is different in every type of your cells. And the way this relates back to cancer, with , in those patients, the tagging is messed up. The patterns are not correct. Our big contribution to that is we've explained how the in the enzyme could lead to that disruption of the tagging pattern."

The UCSB group developed a test to demonstrate that the mutant enzymes in AML can only work on DNA for short distances. As a result, the precise methylation patterns of a healthy cell are disturbed, resulting in genes being turned on at the wrong place and time, which in turn can initiate the growth of cancerous cells.

The team found that the mutation AML patients have causes a certain complex of four proteins to be disrupted. "The surprise was that the disruption doesn't stop the enzyme from being active; it doesn't stop the enzyme from tagging the DNA," said Reich. "Instead, it stops the way it can do it. Instead of going to your DNA and tagging an entire region of chromosome, it goes there, does one thing, and leaves. That process, that change, is what we see in the AML patients. So we think we have a molecular explanation for this disease."

Reich said that the currently prescribed drug Vidaza works by affecting the same enzyme that is mutated in AML. There is interest in the pharmaceutical industry in developing other therapeutics to target the enzymes responsible for tagging the DNA. These epigenetic inhibitors would reprogram rather than kill the cell.

Traditional cancer therapies use radiation and chemotherapy to remove or kill cancer cells. "The problem with that is that cancer cells are often very subtly different from normal cells," said Reich. "So you have one of the most difficult therapeutic challenges known to man, which is to distinguish between two human cells –– one that's cancerous and one that's not. Instead of killing the cell, the notion is that if you could just reprogram the cell, then it goes back to being normal. You intercept the cancer development. This is still an aspiration; it hasn't been achieved really, but that's what attracts people to the field of epigenetic-based therapies, because of the prospect of not having to kill cells."

Provided by University of California - Santa Barbara (news : web)

Researchers model potential of toxic algae photoreceptors

Massimo Olivucci, Ph.D., a research professor of chemistry at Bowling Green State University (BGSU), is focusing on Anabaena sensory (ASR) bacteria, which has served as a model for studies of most cyanobacteria since its genome was fully mapped in 1999.

"An in-depth understanding of light sensing, harvesting and in Anabaena may allow us to engineer this and related organisms to thrive in diverse illumination conditions," said Olivucci. "Such new properties would contribute to the field of alternative energy via the microbial conversion of light energy into biomasses, oxygen and hydrogen. Biophysical studies of the bacterial and its underlying can help us to understand its biotechnological potentials and the associated ."

Using sunlight as an energy source, a sensory protein within ASR detects light of two different colors and behaves like the "eye" of Anabaena, using its green-light sensitivity to activate a cascade of reactions. In sophisticated computer simulations Olivucci created at the Ohio Supercomputer Center (OSC), he found that a short fragment of the long retinal chromophore backbone of ASR undergoes a complete clockwise rotation powered by the energy carried by two photons of light.

"We are constructing quantum-mechanical and molecular-mechanical models on systems," Olivucci explained. "Past simulations have revealed that light induces a molecular-level rotary motion in the protein interior.

"Now, the same computer models will be used to engineer hundreds of mutants that display programmed spectroscopic, photochemical and photobiological properties and identify which mutants should be prepared in the laboratory. This new approach constitutes a unique opportunity for developing computational tools useful for understanding the molecular factors that control the spectra of proteins and their photo-responsive properties in general."

Olivucci's research is expected to lead to an unprecedented tool by which hundreds to thousands of mutant models can be screened for wanted properties, such as color, excited state lifetime or photochemical transformations. This will provide tailored genetic materials for generating organisms that, for instance, can thrive under alternative light conditions and modulate biomass production or be used in engineering applications.

"Ohio is an international player in the biosciences and energy/environmental issues, which is why OSC focuses many of its resources and services on those areas to support important research like this cyanobacteria study," said Ashok Krishnamurthy, Ph.D., interim co-executive director of OSC. "Dr. Olivucci's computational investigations into the potential uses of Anabaena are a great example of how modeling, simulation and analysis can advance research into subjects only imagined just a few short years ago."

More information: Olivucci's research project, "Computational engineering and predictions of excited state properties of bacterial photoreceptor mutants," is supported by the Ohio Board of Regents and BGSU. Initial computational work relating to the project was published in the prestigious Proceedings of the National Academy of Sciences in 2010.

Provided by Ohio Supercomputer Center

Hot attraction in bimetals: A cyano-bridged vanadium-niobium bimetal assembly with a Curie temperature of 210 K

On the basis of initial studies indicating that an increased stoichiometry of vanadium(II) led to a higher Curie temperature in vanadium hexacyanochromate systems, Ohkoshi et al. used a small amount of VIII as catalyst to convert a higher proportion of VII in a similar system. The magnetic properties of the resulting octacyano-bridged vanadium–niobium bimetal assembly were investigated. The compound, whose formula was determined to be K0.59VII1.59VIII0.41[NbIV(CN)8] ·(SO4)0.50·6.9H2O, is ferrimagnetic, and the spins on VII and VIII are antiparallel with respect to the spin on NbIV. Its Curie temperature is 210 K. This high value is a result of the enhanced superexchange interaction through the VII–NC–NbIV pathway.

This study reports a strategy to synthesize magnetic materials with high Curie temperature to enhance the suitability of their for applications.

More information: Shin-ichi Ohkoshi, A Cyano-Bridged Vanadium–Niobium Bimetal Assembly Exhibiting a High Curie Temperature of 210 K, European Journal of Inorganic Chemistry,

Provided by Wiley (news : web)