Simple method of dealing with harmful radioactive iodine discovered

A novel way to immobilise radioactive forms of iodine using a microwave, has been discovered by an expert at the University of Sheffield.

Iodine radioisotopes are produced by fission of uranium fuel in a nuclear reactor. Radioactive iodine is of concern because it is highly mobile in the environment and selective uptake by the thyroid gland can pose a significant cancer risk following long term exposure. Furthermore, iodine-129, which is a type of radioactive iodine, has an extremely long half life of 15.7 million years, so is one of the most significant long term hazards faced by the population due to its emission during the geological disposal of nuclear waste.

Professor Neil Hyatt, from the University's Department of Materials Science and Engineering, has now found a way of locking up iodine radioisotopes in a durable, solid material suitable for ultimate disposal, like lead iodovanadinite(Pb5(VO4)3I). The research, which was published in the Journal of Nuclear Materials, demonstrates how his simple, inexpensive and rapid method can be done at atmospheric pressure.

Professor Hyatt and his team created a solid material for immobilisation of iodine with the formula Pb5(VO4)3I, by heating a mixture of lead iodide, lead oxide and vanadium oxide.

Previously, this has only been achieved using high pressure and a sealed container, because iodine is volatilised at high temperature. However, using the knowledge that vanadium is a good absorber of microwaves at 2.45 GHz – the frequency used in domestic microwave ovens – the team were able to heat the mixture of chemicals in a microwave oven to produce Pb5(VO4)3I in about three minutes.

The key to the method's success is that Pb5(VO4)3I is a poor absorber of 2.45 GHz microwaves, so once this is formed, the sample cannot absorb microwaves, so the temperature does not get high enough for the iodine to volatilise.

Iodine-131 was the harmful gas emitted from the Fukushima power plant in Japan following the earthquake and tsunami last month, and was a significant contributor to the health effects from open-air atomic bomb testing in the 1950s, and was also emitted during the Chernobyl disaster. It is hoped the new research will reduce the public health impact associated with the release of radioactive iodine to the environment by providing a simple and inexpensive method of immobilisation in a solid material, which could be rapidly deployed in an accident scenario.

Professor Neil Hyatt, said: "In spent nuclear fuel, the iodine is not immobilised, so once the containment is breached it simply gets dispersed. At present, iodine-129 released by nuclear fuel reprocessing is discharged direct to the Irish Sea off the coast of Sellafield. Substantial quantities of this radioisotope were also released into the sea off the coast of Japan in the Fukushima incident. Our new method offers a way of safely and rapidly containing this radionuclide, reducing the potential long term impact on human health from discharge to the environment."

More information: Rapid synthesis of Pb5(VO4)3I, for the immobilisation of iodine radioisotopes, by microwave dielectric heating, doi:10.1016/j.jnucmat.2011.04.041

Abstract
Rapid synthesis of Pb5(VO4)3I, a potential immobilisation host for iodine radioisotopes, was achieved in an open container by microwave dielectric heating of a mixture of PbO, PbI2, and V2O5 at a power of 800 W for 180s (at 2.45 GHz). The resulting ceramic bodies exhibited a zoned microstructure, differentiated by inter-granular porosity and phase assemblage, as a consequence of the inverse temperature gradient characteristic of microwave dielectric heating. Liquid PbI2 within the interior of microwave processed ceramics assisted formation of Pb5(VO4)3I, and reduced inter-granular porosity. In contrast, the exterior of microwave processed ceramics comprised poorly sintered Pb5(VO4)3I with the presence of minor reagent relics. Quantitative microanalysis, electron diffraction and Rietveld analysis, confirmed the synthesis of stoichiometric Pb5(VO4)3I within precision. The crystal structure of Pb5(VO4)3I was found to adopt space group P63/m with a = 10.4429(3) A and c = 7.4865(2) A.

Provided by University of Sheffield

'Sweet wheat' for tastier and more healthful baking

"Sweet wheat" has the potential for joining that summertime delight among vegetables — sweet corn — as a tasty and healthful part of the diet, the scientific team that developed this mutant form of wheat concludes in a new study. The report appears in the ACS' Journal of Agricultural and Food Chemistry.

Just as sweet corn arose as a mutation in field corn — being discovered and grown by Native American tribes with the Iroquois introducing European settlers to it in 1779 — sweet wheat (SW) originated from mutations in field wheat. Toshiki Nakamura, Tomoya Shimbata and colleagues developed SW from two mutant types of wheat that each lack a different enzyme needed to make starch. Because the new wheat has much more sugar than regular wheat, they called it "sweet wheat." To see whether the flour from this new wheat could be used as an ingredient in foods, such as breads and cakes, the researchers analyzed its components.

They found that SW flour tasted sweeter, and SW seeds and flour contained higher levels of sugars, lipids and dietary fiber than seeds and flours of other wheat varieties. "The specific compositional changes that occurred in SW seed suggest that SW flour may provide health benefits when used as a food ingredient," say the researchers, noting its high levels of healthful carbohydrates termed fructans.

More information: High Levels of Sugars and Fructan in Mature Seed of Sweet Wheat Lacking GBSSI and SSIIa Enzymes, J. Agric. Food Chem., 2011, 59 (9), pp 4794–4800. DOI: 10.1021/jf200468c

Abstract
Sweet wheat (SW), which lacks functional granule-bound starch synthase I (GBSSI) and starch synthase IIa (SSIIa), accumulates high levels of free sugars in immature seeds. Here, we examined the effects of the lack of these two enzymes on mature kernel composition. Whole grain flour of SW had higher levels of sugars, particularly maltose, slightly higher ash and protein content, approximately two to three times higher lipid levels, and about twice as much total dietary fiber as parental or wild-type lines. Considerably higher levels of low-molecular-weight soluble dietary fiber (LMW-SDF), largely consisting of fructan, were also detected in SW. Although there were no differences in total amino acid levels, the free amino acid content of SW was approximately 4-fold higher than that of wild type, and the levels of certain free amino acids such as proline were particularly high. Thus, we were able to clearly demonstrate that the lack of GBSSI and SSIIa caused dramatic changes in mature seed composition in SW. These compositional changes suggest that SW flour may provide health benefits when used as a food ingredient.

Provided by American Chemical Society (news : web)

Scientists discover new hitch to link nerve cell motors to their cargo

from the blink of an eye to running a marathon—nerve cells transmit signals to muscle cells. To do that, nerve cells rely on tiny molecular motors to transport chemical messengers (neurotransmitters) that excite muscles cells into action. It's a complex process, which scientists are still trying to understand. A new study by Syracuse University researchers has uncovered an important piece of the puzzle.

The study, published in the April 22 issue of the Journal of Biological Chemistry (JBC), describes the discovery of a protein that is involved in the motor-cargo mechanism that carries neurotransmitter chemicals to the nerve cell's synapse. The synapse is the junction at which electrical and chemical signals are transmitted from one nerve cell to another cell. JBC is the premier journal of the American Society for Biochemistry and Molecular Biology.

The discovery was made by a team of scientists led by George M. Langford, a cell biologist and dean of SU's College of Arts and Sciences. Team members included research associate Torsten Wollert and assistant professor Michael Cosgrove in the Department of Biology; and collaborators from Dartmouth College, the Marine Biological Laboratory at Woods Hole, and the McLaughlin Research Institute. The study was funded by the National Institutes of Health.

"The transportation of neurotransmitter vesicles to the synapse is critical to nerve cell function," Langford says. "We want to better understand all of the molecular components involved in the transport process. We have discovered another 'hitch' that links the motor to its cargo."

New insights into how the chemicals are transported could result in new kinds of drug therapy for such illnesses as Parkinson's disease, depression and injuries to the neuromuscular system, Langford says.

Neurotransmitters, produced by nerve cells, are used to signal cells in every organ system in the body—from muscles to metabolism. The chemicals are packaged in small sacs called synaptic vesicles. The motors transporting these vesicles are composed of a protein called myosin-Va (Myo5a). Until now, it was not clearly understood how the Myo5a motor attached to the vesicle. In a series of experiments, Langford's team demonstrated, for the first time, that Myo5a forms a complex with the protein Rab3A, which serves as the 'hitch' that snags the synaptic vesicle.

By understanding how the process works in normal cells, it's possible for scientists to find ways to turn off a malfunctioning transportation system, Langford says. For example, over-production of the neurotransmitter dopamine has been linked to depression and other mental illnesses. It may be desirable to develop drugs that prevent dopamine from being transported. Likewise preventing the transportation of muscle-contracting neurotransmitters could ease painful muscle spasms associated with Parkinson's disease and severe, nervous system injuries.

Langford's research has been dedicated to understanding how organelles move within cells. He was the first to observe the movement of synaptic vesicles on actin filaments in addition to their previously known transportation on microtubules within nerve cells. Actin filaments and microtubules are the roads on which the molecular motors transport their cargo. "Think of microtubules as the expressways in the nerve cells and the actin filaments as the local streets," Langford says.

In addition to his work on cellular transport mechanisms, Langford is researching ways to produce more effective drugs to treat Candida albicans, a fungus that causes infections in humans.

Provided by Syracuse University

Scientists uncover chemical transformations in cobalt nanoparticles

 The evolution schematics of transition from cobalt to cobalt phosphide nanocrystals.

Understanding the intricacies of how nanoparticles undergo chemical transformations could lead to better ways to tailor their composition, which can lead to advanced material properties.

Using the Cornell High Energy Synchrotron Source, scientists led by Richard Robinson, assistant professor of materials science and engineering, uncovered exactly what happens when cobalt nanoparticles transform into two phases of cobalt phosphides.

Their work, published in the Journal of Materials Chemistry, was featured by the journal as a "Hot Article" earlier this month.

The effect Robinson's team observed in the cobalt phosphide transitions was a nanoparticle hollowing due to asymmetric diffusivities of cations and anions. In other words, the cations move out from the core faster than anions can diffuse in, leading to a hollow particle.

Other groups have reported on this "Kirkendall" effect, but the Robinson team was the first to show that this hollowing is more complex than previously thought and can be studied as a two-step process. Their work could be used to control this process and produce complex particles with properties tailored for use in energy applications. Metal phosphides have a wide range of properties -- ferromagnetism, superconductivity, catalytic activity and magnetoresistance among them.

The work was done in collaboration with scientists led by Richard Hennig, assistant professor of materials science and engineering. It was supported by King Abdullah University of Science and Technology, the Cornell Center for Materials Research and the Energy Materials Center at Cornell.

Provided by Cornell University (news : web)

Trash to treasure: Turning steel-mill waste into bricks

Scientists are reporting development and successful testing of a promising new way of using a troublesome byproduct of the global steel industry as raw materials for bricks that can be used in construction projects. Their study appears in ACS' Industrial & Engineering Chemistry Research.

In the report, Ana Andrés and colleagues note that steel mills around the world produce vast quantities of waste dust each year — 8 million – 12 million tons in the United States, for instance, and 700,000 tons in the European Union countries. The dust often is converted into a rock-like material known as Waelz slag, which is usually disposed of in landfills.

The slag contains iron, calcium, silicon oxide and other minor oxides as manganese, lead or zinc oxide. Scientists have been searching for practical and safe uses for Waelz slag. In earlier research, scientists showed that Waelz slag had potential as an ingredient in bricks, roof tiles and other ceramic products. The new research moves large-scale recycling of Waelz slag closer to reality, establishing at two real-world brick factories that the material can successfully be incorporated into commercial-size bricks.

It showed existing commercial equipment could be used to make bricks with Waelz slag, and eased concerns about large amounts of potentially toxic metals leaching out of such bricks. A small amount of potentially toxic material came out of the slag-made bricks over time, not in excess of European Union regulations. "Overall, it may be summarized that Waelz slag containing bricks meet the highest quality standards set for construction ceramic materials," the researchers say.

More information: Incorporation of Waelz Slag into Commercial Ceramic Bricks: A Practical Example of Industrial Ecology, Ind. Eng. Chem. Res., 2011, 50 (9), pp 5806–5814. DOI: 10.1021/ie102145h

Abstract
The recovery of electric arc furnace (EAF) dust generates large amounts of an industrial byproduct called Waelz slag. This residue, consisting primarily of iron oxide contaminated with other metal oxides (including zinc and lead), is usually disposed of in landfill sites at a high economic and environmental cost. This paper investigates an alternative based on industrial ecology principles, which involves the incorporation of Waelz slag into clay ceramic construction bricks. For the purpose of this work, Waelz slag and raw materials employed in the manufacture of ceramic bricks (natural clays, wood pulp) were characterized. Subsequently, a series of brick specimens were manufactured according to commercial mixes and using industrial equipment and procedures. Similar specimens were also produced replacing 20-30 wt % of the clay with Waelz slag. The resulting products were analyzed for their physical (bulk density, water absorption, open porosity), mechanical (modulus of rupture), and chemical properties (soluble salts content) in order to evaluate compliance with quality standards for construction materials. The environmental consequences of incorporating slag into ceramic products were also investigated at three stages of their life cycle: release of potentially toxic species during their use (NEN 7345), leaching of heavy metals after disposal in landfill sites (EN 12457 1 and 2), and emission of atmospheric pollutants during the firing process. The experimental results demonstrate that incorporation of Waelz slag does not deteriorate the physical, mechanical, and chemical properties of the resulting products. The leaching of species during its useful lives show compliance with threshold values established according to the Dutch Building Materials Decree (DBMD), and Waelz slag containing bricks fall into the category of nonhazardous waste landfill, just like conventional bricks used at this work. Emissions of CO2 and NOx were reduced versus the emissions of halogenated gases and SO2, which were favored due to the thermal decomposition of S, Cl, and F contained in the waste material.

Provided by American Chemical Society (news : web)