Tuesday, December 20, 2011

Making molecular hydrogen more efficiently

Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory have developed an extraordinarily efficient two-step process that electrolyzes, or separates, from before combining them to make (H2), which can be used in any number of applications from fuel cells to industrial processing.

Easier routes to the generation of hydrogen have long been a target of scientists and engineers, principally because the process to create the gas requires a great deal of energy. Approximately 2 percent of all electric power generated in the United States is dedicated to the production of molecular hydrogen, so scientists and engineers are searching for any way to cut that figure. "People understand that once you have hydrogen you can extract a lot of energy from it, but they don't realize just how hard it is to generate that hydrogen in the first place," said Nenad Markovic, an Argonne senior who led the research.

While a great deal of hydrogen is created by reforming at , that process creates carbon-dioxide emissions. "Water electrolyzers are by far the cleanest way of ," Markovic said. "The method we've devised combines the capabilities of two of the best materials known for water-based electrolysis."

Most previous experiments in water-based electrolysis rely on special metals, like platinum, to adsorb and recombine reactive hydrogen intermediates into stable molecular hydrogen. Markovic's research focuses on the previous step, which involves improving the efficiency by which an incoming water molecule would disassociate into its fundamental components. To do this, Markovic and his colleagues added clusters of a metallic complex known as nickel-hydroxide—Ni(OH)2. Attached to a platinum framework, the clusters tore apart the water molecules, allowing for the freed hydrogen to be catalyzed by the platinum.

"One of the most important points of this experiment is that we're combining two materials with very different benefits," said Markovic. "The advantage of using both oxides and metals in conjunction dramatically improves the catalytic efficiency of the whole system."

According to Argonne materials scientist George Crabtree, who helped to initiate the establishment of Argonne's energy conversion program, the researchers' success is attributable to their ability to work on what are known as "single-crystal" systems—defect-free materials that allow scientists to accurately predict how certain materials will behave at the atomic level. "We have not only increased catalytic activity by a factor of 10, but also now understand how each part of the system works. By scaling up from the single crystal to a real-world catalyst, this work illustrates how fundamental understanding leads quickly to innovative new technologies."

This work, supported by the DOE Office of Science, is reported in the December 2 issue of Science.

Provided by Argonne National Laboratory (news : web)

Soy is on top as a high-quality plant protein

Traditional methods for determining quality have shown animal proteins such as milk and eggs to be high in quality. However, those who are interested in a plant-based diet, or diversifying their proteins, have a more difficult time determining which of their choices are high in quality. Testing methods have shown most , such as , are lower in quality than animal-based proteins.

"Accurate methods for determining protein quality are key to helping people plan a healthful diet," said Glenna Hughes, MS, research scientist at Solae. "Due to the increasing interest in including plant-based proteins in the diet, accurate information on protein quality is needed in scientific literature to help educate consumers and on this topic."

The Food and Agriculture Organization (FAO) and the (WHO) recommend using the protein digestibility-corrected amino acid score (PDCAAS) as a simple and scientific procedure for assessing protein quality. The PDCAAS methodology focuses on three different parameters: the amount of each essential amino acid the protein contains, how easily the protein can be digested, and by taking both of those parameters into account, whether the protein meets the FAO/WHO's amino acid requirements set for children aged two to five years, as they have higher needs to support growth and development than adults.

According to this study, has a PDCAAS of 1.00, meaning it is a high-quality protein that meets the needs of both children and adults. Eggs, dairy and meat proteins also have a PDCAAS score of 1.0.

However, soy protein is the only widely available high-quality plant-based protein that achieves this score.

"It's important for people to understand that a plant-based diet is healthy, but that not all proteins are created equal," said Connie Diekman, RD, LD, FADA. "If you are planning a vegetarian diet or want to incorporate plant-based proteins in your diet, understanding protein quality using the PDCAAS scale can allow you to select proteins that score higher, such as soy, to ensure that you are getting the essential amino acids you need."

More information: For more information on the study, the following is a link to the abstract: http://www.ncbi.nl … med/22017752

Provided by Solae, LLC

Pressure prepares lobsters for long-distance delivery

The New England lobster's growing popularity has been accompanied by a drive to develop new methods to get the into hungry mouths worldwide, significantly extending its range from a once purely regional dish.

" has always been a celebration food," said John Hathaway, CEO of Shucks Maine Lobster, based in Richmond, Maine. "Outside New England it's eaten in restaurants particularly for holidays. It's huge in the European Union for Christmas. And Asia is becoming a potentially a huge market for Maine lobsters."

A machine developed by Hathaway increases the promise of selling the shellfish to markets by overcoming the array of problems associated with traditional long-distance delivery methods for New England lobsters. Transporting live lobsters involves a risk that several will die en route. The weight of their shells adds extra freight, and the infrastructure to keep them alive in restaurants before diners order them adds to their overall expense -- which is passed on to customers.

Cooking lobster meat before transporting it creates a different issue.

"The danger is overcooking a casserole or, say, lobster Newburg if the lobster's already been cooked," said Marianne LaCroix, director of marketing for the Maine Lobster Promotion Council.

Hathaway said that pre-cooked lobster "might be good enough for lobster rolls, but if you cook it again, the meat becomes very tough."

The Shucks machine uses pressurized water to remove the meat from the shellfish without cooking it. In addition to enabling the safe and relatively inexpensive transport of raw lobster meat to distant destinations around the world, the system gives chefs an easy way to prepare "lazy man's" lobster.

Unlike the whole boiled lobster beloved by New Englanders, lazy man's lobster dispenses with the shells, the bibs, and the nutcrackers and picks necessary to extract the meat from the shells. That process, known as shucking, can create a messy and embarrassing experience for customers unfamiliar with the minutiae of meat removal.

A ready supply of raw meat removed from the shell precludes the need for kitchen assistants to shuck lobsters for those meals.

The raw material for Hathaway's machine, which he calls the "Big Mother Shucker," consists of lobsters gathered from traps in the cold Atlantic Ocean off the Maine coast.

Workers load about 200 pounds of live lobsters at a time into the machine. At the turn of a switch, fresh water under pressure of 40,000 pounds per square inch floods the device.

"Within 6 seconds the water pressure will kill the animals," Hathaway said.

The high-pressure water breaks chemical bonds within the lobsters' biological cells. That causes the lobsters to die quickly but has no effect on the taste or quality of their meat. The same process also detaches the lobsters' meat from their shells' interiors. By the end of the 6-minute pressure cycle, separation is complete.

Because each part of each lobster experiences the same water pressure, the process does not deform the raw meat. When the workers crack the shell by hand, the parts of a naked lobster emerge.

The human shuckers snap off the tails to remove the tender tail meat, crack the shells with a hammer to take out the claw meat, and remove the thin legs for shucking by a machine.

Once removed, the meat is cooled on ice, packaged, and vacuum sealed. Another treatment with the water, this time at a pressure of 87,000 pounds per square inch, serves to remove any pathogens and bacteria introduced during processing. The company then ships the packages to wholesalers and distributors in North America and beyond.

"We ship the meat frozen or fresh," Hathaway said. "The fresh product has a 30-day shelf life and we offer a shelf life of 18 months to two years for the frozen product."

A more traditional method of preparing lobster meat for transportation -- blanching -- remains popular. "You boil or steam the lobster to cook it for about 2 minutes rather than 12 or 13," LaCroix explained. "This kills the lobster and allows you to extract the meat [without cooking it completely]."

Hard-shell lobsters are often shipped live, in cardboard or plastic boxes kept damp with, for example, wet newspaper. Sometimes during particularly long journeys, LaCroix said, "There are stopping points halfway where the lobsters can be put into water to recover." But not surprisingly, she added, "Mortality is higher on the way to Asia than to New York."

Hathaway learned about the pressurized water technology in 2005, when he ran a traditional lobster shack in Kennebunkport, Maine.

"I knew that it meant an opportunity to get into the Maine lobster business," Hathaway recalled. "I bought the machine, found a place to put it, but had no idea what to do with it."

That indecision didn't last long. Winning a prize for his raw lobster meat at the European Food Exposition in Brussels, Belgium in 2007 convinced Hathaway of the value of his technology.

"And each year since then,” Hathaway said, "we have grown considerably."

Source: Inside Science News Service (news : web)

Neutrons answer shampoo formulation puzzle

A research team at the Institut Laue-Langevin, the flagship centre for , has demonstrated quantitatively the science behind an anomaly in the of polyelectrolyte/surfactant mixtures. Their findings show that the dramatic increase in surface tension that affects the production of various pharmaceutical and cosmetic formulations is caused by the comprehensive aggregation of active ingredients. They have outlined a way to reload interfaces with functional components simply by tuning the way the materials are handled.

Surface tension is a property of liquids resulting from the cohesion of their molecules that helps them resist an external force. It is responsible for the shape of and the reason why insects can run on the surface of ponds.

Surfactants are substances that lower the surface tension of a liquid and can capture other substances, such as oil or grease in cleaning products. They are often combined with polyelectrolytes, made of long charged molecules, to improve the efficiency of , wetting agents, emulsifiers, foaming agents, and in paints, shampoos and conditioners, and are used throughout the food industry. Also, the strong attractive interactions of surfactants with natural polyelectrolytes, such as proteins or DNA, play an important role in many biological processes, as well as in medical applications, such as drug and .

The commercial production and performance of polyelectrolyte/surfactant mixtures, however, is affected by a peculiar phenomenon, first investigated in depth a decade ago. Whilst adding a surfactant to a polyelectrolyte solution initially causes the surface tension to decrease, as further surfactant is added the surface tension dramatically increases again. This feature, known as a ‘cliff edge peak’, is accompanied by a change in the appearance of the mixture, with the eventual loss of the cloudiness that is present as soon as the materials first interact.

From an industrial production point of view, this rise in surface tension reduces the performance of the additive, often requiring the introduction of further surfactant at extra cost. As a result, there is a lot of interest in understanding the interactions between these mixtures at the atomic level both in solutions and at surfaces. Of particular interest are the primary causes of the cliff edge peak and ways to prevent, lessen or delay its effects that could lead to more efficient formulations and reduce the effects of many pollutants in our environment.

To investigate this problem, Dr Richard Campbell (Institut Laue-Langevin), Dr Imre Varga (Eötvös-Loránd University, Hungary) and their co-workers looked at a system studied widely in the literature – an oppositely charged poly (diallyldimethylammonium chloride)/sodium dodecyl sulfate (Pdadmac/SDS) system.

The international research team, which also includes members from the UK and Sweden, used neutron reflectometry, a reflection technique used for measuring the composition and structure of thin films, to monitor the surface properties with respect to the slow generation of the cliff edge peak. The instrument used was the brand new FIGARO reflectometer (Fluid Interfaces Grazing Angles ReflectOmeter) at the Institut Laue-Langevin, which was constructed during the Institute’s innovative Millennium Programme. The researchers showed quantitatively for the first time that this striking feature in the surface tension results from the slow precipitation of particles into sediment from the aqueous solution. The precipitation depletes the solution and consequently the surface of its active ingredients, and also accounts for the loss of cloudiness observed.

As well as uncovering the reasons behind the rise in surface tension, the team were also keen to investigate methods to prevent its impact, which could directly benefit commercial applications. In the literature, researchers have suggested that the way these mixtures are handled could affect the nature of the material in the solution - a phenomenon called “non-equilibrium effects”.

To test whether the re-dispersion of surface-active material could actually switch off the cliff edge peak effect, the team carefully agitated a series of mixtures after the settling process had finished. A small mechanical stress provided just enough energy to re-disperse some of the sedimented particles and re-supplied the air/liquid interface with enough material to lower the surface tension once again.

“By approaching the problem in a different way, we have shown that the way you handle polyelectrolyte/ systems can produce a variety of tuneable surface properties,” says Dr. Richard Campbell. “We hope that our findings will allow future industrial chemists across the pharmaceutical, detergency and cosmetic industries to generate better product output from their raw materials by learning to handle them in a smarter way, and create optimum surface properties on demand, rather than simply buying in more material to improve performance.”

There is hope also that this work can lead on to novel drug or gene delivery applications where one could apply an external stimulus to a stable biomacromolecule system in order to trigger the delivery of proteins or DNA to a given target.

More information: Re.:J. Phys. Chem. B, Article ASAP, DOI: 10.1021/jp2088803

Provided by Institut Laue-Langevin