Thursday, June 2, 2011

Study finds common fire retardant harmful to aquatic life

A new study by Baylor University environmental health researchers found that zebra fish exposed to several different technical mixtures of polybrominated diphenyl ethers (PBDEs) – a common fire retardant – during early development can cause developmental malformations, changes in behavior and death.

The study will appear in the June issue of the journal Environmental Toxicology and Chemistry and is the first to test multiple PBDE for changes in behavior, physical malformations and mortality on .

PBDEs are found in many common household products from blankets to couches to food wrappers. Lab tests have shown that PBDEs have been found in human breast milk and cord blood. Previous studies have showed children with high levels of PBDEs in their umbilical cord at birth scored lower on tests between one and six years of age. In 2006, the state of California started prohibiting the use of PBDEs.

The family of PBDEs consists of more than 200 possible substances, which are called congeners. Congeners are considered low if they average between 1 to 5 bromine atoms per molecule.

The Baylor researchers tested six PBDE congeners for developmental effects on embryonic zebra fish. Changes in behavior, physical malformations and mortality were recorded daily for seven days.

The results showed:
Lower brominated congeners were more toxic than higher brominated congeners.
Embryos were most sensitive to two particular types of PBDE exposures, the two lowest brominated congeners of the six tested. Both induced a curved body axis and eventually death.
In all, four of the six congeners tested caused developmental malformations, such as a curved body axis and pulmonary edema. Five of the six caused alterations in behaviors, such as decreased swimming rates and increased spontaneous movement in the embryo. "While most PBDEs have either been banned or phased out throughout the world, it may be more beneficial to identify congeners of concern rather than replacing these compounds with chemicals of unknown biological interactions," said Dr. Erica Bruce, assistant professor of environmental science at Baylor who is an expert in environmental chemicals and their effects on public health. "Alterations in early behavior may potentially be due to disruption of thyroid hormones. Thyroid hormones play a vital role in the development of the cholinergic system and this study gives insight into biological interaction within a few hours of exposure. The observed hyperactivity may be due to overstimulation of the cholinergic system," Bruce said.

Provided by Baylor University

Biochemists reveal new twist on old fuel source

Stinging from humiliating defeat in World War I, Germany’s Nazi regime seized on technology developed by chemists Franz Fischer and Hans Tropsch that enabled the coal-rich, petroleum-poor country to produce synthetic fuels for its military machine. Research in Fischer-Tropsch or “FT” synthesis waned in the latter half of the 20th century but, like “a bubblin’ crude,” has resurfaced in recent years with growing interest in alternative fuels.

While studying bacterial enzymes, known as nitrogenases, used in nitrogen reduction, Utah State University biochemists Zhi-Yong Yang and Lance Seefeldt, along with colleague Dennis Dean of Virginia Tech, discovered a molybdenum nitrogenase capable of converting into usable hydrocarbons. The reaction is similar, they say, to FT synthesis.

“This is pretty profound,” says Seefeldt, professor in USU’s Department of Chemistry and Biochemistry. “Understanding this process paves the way for developing better ways of converting carbon monoxide, a toxic waste product of combustion, into transportation fuel and precursors for plastics – without the time and energy required for conventional extraction of fossil fuels.”

The scientists’ findings appear in the article “Molybdenum Nitrogenase Catalyzes the Reduction and Coupling of CO to Form Hydrocarbons,” in the June 3, 2011 issue (and May 27 online issue) of . The paper was selected as “Paper of the Week” by the journal’s editorial board, an honor bestowed on the top one percent of more than 6,600 manuscripts reviewed annually

by the publication’s editors. In the “Paper of the Week” feature, Yang, a doctoral candidate mentored by Seefeldt, is highlighted as an up-and-coming researcher.

Molybdenum, often called “Moly,” is a brittle, silver-gray metal found in soil and used in steel alloys. It’s also found, in small amounts, in the human body, where it metabolizes certain amino acids, produces uric acid and helps to break down drugs and toxins.

“There’s tremendous interest in converting various kinds of waste into fuel and, especially, in finding cost-effective and environmentally clean ways to do it,” says Yang, who earned his first doctorate in organic chemistry at China’s Nankai University.

Unlike coal, Fischer and Tropsch’s original source for synthetic fuels, carbon monoxide produces hydrocarbons with much less pollution. The substance provides an added benefit: it allows scientists to produce longer chain, double and triple-bond hydrocarbons, which provides a richer feedstock for production of refined transportation fuels.

“Like many waste-to-energy processes, we’ve found we can produce such hydrocarbons as propane and butane from carbon monoxide,” Yang says. “But using this process, we may have the potential to produce such transportation fuels as diesel and gasoline that are readily adaptable to today’s vehicles.”

Dinitrogen, Seefeldt says, makes up about 80 percent of the air we breathe. Though essential for all life on the planet, it’s not in a form higher organisms can directly access.

“It’s kind of like being hungry and sitting at a table laden with food but not being able to eat,” he says.

Humans and animals take in nitrogen – in the form of protein – from food; plants obtain nitrogen from soil.

In recent years, Seefeldt has identified key steps involved in nitrogen fixation, the process by which nitrogen is converted to ammonia. The findings contribute to research that could enable an alternative, clean method of producing nitrogen.

Science and industry currently rely on the century-old Häber-Bosch process to produce nitrogen for fertilizer, paper, pharmaceuticals, plastics, mining and explosives. Developed by German Nobel Prize winner Fritz Häber and Carl Bosch during World War I, the process, Seefeldt says, is costly and energy-intensive.

Provided by Utah State University

From the rustbelt: An iron-based flow battery

Researchers at Case Western Reserve University are mixing cheap and plentiful iron in benign solutions to create a flow battery – essentially an unwrapped battery that can be scaled up to hold and supply electricity to a home or an entire community.

The goal is to produce a cheap and efficient system capable of storing energy from wind turbines and solar panels and supplying energy when wind wanes and the sun sets. The battery could also be integrated into a smart grid, charging up when usage is low then adding electricity when need is high.

Not only will the flow battery be cheaper and more efficient than current models, but much more environmentally friendly, the researchers say.

"We like to call this the rustbelt battery," said Robert Savinell, professor of chemical engineering at Case Western Reserve.

Savinell proposed an iron-based flow battery 30 years ago but the energy industry was more interested in other technologies. Now, with the move toward sources of intermittent energy and increased gird efficiency, such a storage system could be one answer to 21st-century needs.

Savinell and Jesse Wainright, a fellow chemical engineering professor at Case School of Engineering, have begun a three-year project to fine tune the chemistry, develop the cleanest, most efficient system, and build a working model proving the technology.

The Department of Energy's Office of Electricity Delivery and Energy Reliability, through Sandia National Laboratory, is funding the research with a $600,000 grant.

For large-scale energy storage, a flow battery has significant advantages over a standard battery.

In standard batteries, power and energy densities are limited by wrapping all the materials used to convert chemical energy into electrical energy inside of a single cell. The electrodes, which are part of the fuel, are consumed over time, leading to performance loss.

In flow batteries, chemical reactants used to produce electrical energy are stored in two tanks and the electrodes, which are not used as fuel, are housed in a separate chamber. The reactants are pumped one direction through the chamber to charge the battery and the other direction to discharge the system.

Power and energy density can be increased by increasing the volume of reactants.

The most common flow batteries are based on vanadium, a metal mined primarily in Russia, China and South Africa, and which has recently cost from $8 to $20 per pound in the pentaoxide form. , which is plentiful in the U.S., has recently been selling for less than 25 cents per pound as anhydrous ferrous chloride, or on a metal basis less than 1% of the cost of vanadium.

Vanadium batteries use highly-corrosive sulfuric acid for the electrolyte. For safety reasons, the researchers plan to use a benign electrolyte with a pH of about 4.

"Since these systems will be very large, we're very conscious of the hazards that could arise from an accident," Wainright said. "We're focusing our efforts on developing a safe chemistry; I wouldn't want to put anything in the battery that you couldn't swim in."

A large-scale storage facility that could accommodate a wind farm by storing up to 20 megawatt-hours of electricity would require two storage tanks for the iron solutions of about 250,000 gallons – or 8 railroad tank cars each, he explained.

A system that size could supply the power needs of 650 homes for a day.

Flow batteries can be a useful alternative to storage technologies such as pumped hydro and compressed air systems, which require large water supplies and land with mixed elevations, or access to airtight caverns, Savinell said.

When demand is low, pumped hydro stations use excess electricity to pump water from a river or reservoir to a reservoir at a higher elevation. When demand rises, the water is released downhill through turbines that produce electricity. Compressed air stations pump air into caverns when demand is low then release the compressed air through turbines to produce electricity as demand increases.

The efficiency of the systems can reach about 75 percent. Savinell and Wainright estimate the iron flow battery can reach 80 percent.

Sandia set a goal of creating new kinds of storage systems that would cost $100 per kilowatt-hour produced.

The researchers estimate, because of the low cost of components, that the iron-based would cost $30 per kilowatt-hour.

Provided by Case Western Reserve University (news : web)

New clues to how humble painkiller stifles cancer growth

One of our scientists has shed light on how a common class of painkillers – which includes ibuprofen – may interact with a key protein that fuels the growth of many different types of cancer, according to a study published in the journal Chemical Communications this week.

Ibuprofen is one of several ‘profens’ – a particular group of non-steroidal anti-inflammatory drugs (NSAIDs) – being investigated for their ability to prevent cancer.

Our research team, from the Department of Pharmacy & Pharmacology, carried out an analysis of drugs in the same class as and discovered that they are all processed by the body in exactly the same way – through a protein called AMACR, which converts the into its active form.

AMACR is overactive in almost all prostate cancers, some bowel cancers and several other types of cancer and is thought to fuel the growth of the disease by boosting the cell’s energy supply.

So understanding how drugs like ibuprofen might alter AMACR activity could help scientists better understand how they are able to block cancer growth.

Lead author Dr Matthew Lloyd, said: “Our study is the first to test other drugs in the same family as ibuprofen systematically and show that they‘re all processed by the same protein in the body. Some early laboratory studies have suggested that high doses of ibuprofen can halt the growth of prostate cancer cells, but the reasons for this aren’t well understood.

“Understanding more about how this protein is acting in cells and what molecules it interacts with could provide important clues to how this process works, hopefully opening up new avenues of research for treating prostate cancer in the future.”

Dr Julie Sharp, senior science information manager at Cancer Research UK, said: “This research is part of an international effort to understand how drugs like ibuprofen could prevent, or slow down, the development of . But there are risks as well as benefits and long term use of these drugs can have side effects, such as bleeding and stomach ulcers. Understanding more about how these drugs work on a molecular level is a crucial step in being able to develop better targeted drugs with fewer side effects in future.”

For the full paper please see: Chiral inversion of 2-arylpropionyl-CoA esters by human ?-methylacyl-CoA racemase 1A (P504S)—a potential mechanism for the anti-cancer effects of ibuprofen.

Provided by University of Bath (news : web)