Nanoscale crystals is far stronger and harder than iron

Researchers at North Carolina State University have created a substance far stronger and harder than conventional iron, and which retains these properties under extremely high temperatures – opening the door to a wide variety of potential applications, such as engine components that are exposed to high stress and high temperatures.

Iron that is made up of nanoscale crystals is far stronger and harder than its traditional counterpart, but the benefits of this “nano-iron” have been limited by the fact that its nanocrystalline structure breaks down at relatively modest temperatures. But the NC State researchers have developed an iron-zirconium alloy that retains its nanocrystalline structures at temperatures above 1,300 degrees Celsius – approaching the melting point of iron.

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Kris Darling, a Ph.D. student at NC State who led the project to develop the material, explains that the alloy’s ability to retain its nanocrystalline structure under high temperatures will allow for the material to be developed in bulk, because conventional methods of materials manufacture rely on heat and pressure.

In addition, Darling says the ability to work with the material at high temperatures will make it easier to form the alloy into useful shapes – for use as tools or in structural applications, such as engine parts.

The new alloy is also economically viable, since “it costs virtually the same amount to produce the alloy” as it does to create nano-iron, Darling says.

Dr. Carl C. Koch, an NC State professor of materials science engineering who worked on the project, explains that the alloy essentially consists of 1 percent zirconium and 99 percent iron. The zirconium allows the alloy to retain its nanocrystalline structure under high temperatures.

Source: North Carolina State University

Fungus improves corn-to-ethanol process

Growing a fungus in some of the leftovers from ethanol production can save energy, recycle more water and improve the livestock feed that's a co-product of fuel production, according to a team of researchers from Iowa State University and the University of Hawaii.

"The process could change ethanol production in dry-grind plants so much that energy costs can be reduced by as much as one-third," said Hans van Leeuwen, an Iowa State professor of civil, construction and environmental engineering and the leader of the research project.

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Van Leeuwen and the other researchers developing the technology -- Anthony L. Pometto III, a professor of food science and human nutrition; Mary Rasmussen, a graduate student in environmental engineering and biorenewable resources and technology; and Samir Khanal, a former Iowa State research assistant professor who's now an assistant professor of molecular biosciences and bioengineering at the University of Hawai'i at Manoa -- recently won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.

"Those chosen for prizes by an independent panel of distinguished experts address the broad range of modern challenges inherent in providing life-nurturing services for humans and protection of the environment," according to a statement from the academy. "... Their innovations and performance illustrate the essential role of environmental engineers in providing a healthy planet."

The Iowa State project is focused on using fungi to clean up and improve the dry-grind ethanol production process. That process grinds corn kernels and adds water and enzymes. The enzymes break the starches into sugars. The sugars are fermented with yeasts to produce ethanol.

The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that's produced. Those leftovers, known as stillage, contain solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.

The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds from corn and fermentation as well as enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.

The researchers added a fungus, Rhizopus microsporus, to the thin stillage and found it would feed and grow. The fungus removes about 80 percent of the organic material and all of the solids in the thin stillage, allowing the water and enzymes in the thin stillage to be recycled back into production.

The fungus can also be harvested. It's a food-grade organism that's rich in protein, certain essential amino acids and other nutrients. It can be dried and sold as a livestock feed supplement. Or it can be blended with distillers dried grains to boost its value as a livestock feed and make it more suitable for feeding hogs and chickens.

Van Leeuwen said all of that can save United States ethanol producers a lot of energy and money at current production levels:

* Eliminating the need to evaporate thin stillage would save ethanol plants up to $800 million a year in energy costs.
* Allowing more water recycling would reduce the industry's water consumption by as much as 10 billion gallons per year. And it allows producers to recycle enzymes in the thin stillage, saving about $60 million per year.
* Adding value and nutrients to the livestock feed produced by ethanol plants would grow the market for that feed by about $400 million per year.
* And the researchers' fungal process would improve the energy balance of ethanol production by reducing energy inputs so there is more of an energy gain.

Van Leeuwen estimated it would cost $11 million to start using the process in an ethanol plant that produces 100 million gallons of fuel per year. But, he said the cost savings at such a plant could pay off that investment in about six months.

The Iowa State research project is supported by grants of $78,806 from the Grow Iowa Values Fund, a state economic development program, and $80,000 from the U.S. Department of Agriculture through the Iowa Biotechnology Byproducts Consortium.

The researchers have filed for a patent on the technology and are looking for investors to commercialize the invention. And while the process needs to be proven at larger scales, there are high hopes it can do a lot to improve the efficiency of ethanol production.

"We will be saving ethanol producers money and energy," Pometto said. "That's the bottom line."

Source: Iowa State University

Smallest magnetic nanoparticles to date for cancer detection

Magnetic resonance imaging (MRI) can be a doctor's best friend for detecting a tumor in the body without resorting to surgery. MRI scans use pulses of magnetic waves and gauge the return signals to identify different types of tissue in the body, distinguishing bone from muscle, fluids from solids, and so on.

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Scientists have found that magnetic nanoparticles can be especially helpful in locating cancerous cell clusters during MRI scans. Like teeny guide missiles, the nanoparticles seek out tumor cells and attach themselves to them. Once the nanoparticles bind themselves to these cancer cells, the particles operate like radio transmitters, greatly aiding the MRI's detection capability.

Now, Brown University chemist Shouheng Sun and a team of researchers have created the smallest magnetic nanoparticles to date that can be employed on such seek-and-find missions. With a thinner coating, the particles also emit a stronger signal for the MRI to detect.

The results have been published online this week in the Journal of the American Chemical Society. Brown graduates students Jin Xie, Chenjie Xu and Sheng Peng collaborated on the research, along with Professor Xiaoyuan Chen and his associates from Stanford University.

The team created peptide-coated iron oxide nanoparticles — particles billionths of a meter in size. The researchers injected the particles into mice and tested their ability to locate a brain tumor cell called U87MG. Sun and his collaborators concentrated specifically on the nanoparticle's size and the thickness of the peptide coating, which ensures the nanoparticle attaches to the tumor cell.

Size is important because the trick is to create a nanoparticle that is small enough to navigate through the bloodstream and reach the diseased area. Bigger particles tend to stack up, creating the circulatory system's version of a traffic jam. Sun's team developed a nanoparticle that is about 8.4 nanometers in overall diameter — some six times smaller than the size of particles currently used in medicine.

"We wanted to make (the nanoparticle) very small, so the body's immune system won't recognize it," Sun explained. "That way, you let more particles interact with and attach to the tumor cell."

Nanoparticles are important in MRI detection because they enhance what scientists refer to as the "contrast" between the background, such as water molecules in the body, and a solid mass, such as a tumor.

The coating, while integral to the nanoparticles' attachment to the tumor cell, also is crucial to establishing the "signal-to-noise" ratio that a MRI uses. The thinner the coating, the stronger the emitted signal and vice versa. Sun's team outfitted their nanoparticles with a two-nanometer thick peptide coating — 10 times thinner than the coating available in popular MRI contrast agents such as Feridex. Sun's nanoparticles are like having a 50,000-watt radio transmitter versus a 150-watt station; it's easier for the MRI to "hear" the stronger signal and to hone in on the signal's source.

Another important feature of the team's work is discovering that the RGD peptide coating binds almost seamlessly to the U87MG tumor cell. The team plans to test the particle's ability to bind with other tumor cells in further animal experiments.

Potential health hazards of buckyballs studied

A new study into the potential health hazards of the revolutionary nano-sized particles known as ‘buckyballs’ predicts that the molecules are easily absorbed into animal cells, providing a possible explanation for how the molecules could be toxic to humans and other organisms.

Using computer simulations, University of Calgary biochemist Peter Tieleman, post-doctoral fellow Luca Monticelli and colleagues modeled the interaction between carbon-60 molecules and cell membranes and found that the particles are able to enter cells by permeating their membranes without causing mechanical damage. Their results are published in the current Advance Online Publication of Nature Nanotechnology, the world’s leading nanotechnology journal.

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“Buckyballs are already being made on a commercial scale for use in coatings and materials but we have not determined their toxicity,” said Tieleman, a Senior Scholar of the Alberta Heritage Foundation for Medical Research who specializes in membrane biophysics and biocomputing. “There are studies showing that they can cross the blood-brain barrier and alter cell functions, which raises a lot of questions about their toxicity and what impact they may have if released into the environment.”

Tieleman’s team used the high-powered computing resources of WestGrid, a partnership between 14 Western Canadian institutions, to run some of the cell behaviour simulations. The resulting model showed that buckyball particles are able to dissolve in cell membranes, pass into cells and re-form particles on the other side where they can cause damage to cells.

Spherical carbon-60 molecules were discovered in 1985, leading to the Nobel Prize in physics for researchers from the University of Sussex and Rice University who named the round, hollow molecules Buckminsterfullerene after renowned American architect Richard Buckminster Fuller, the inventor of the geodesic dome.

Popularly known as buckyballs, carbon-60 molecules form naturally in minute quantities under extreme conditions such as lightning strikes. They can also be produced artificially as spheres or oblong-shaped balls, known as fullerenes, and can be used to produce hollow fibers known as carbon nanotubes. Both substances are considered to be promising materials in the field of nanotechnology because of their incredible strength and heat resistance. Potential applications include the production of industrial materials, drug delivery systems, fuel cells and even cosmetics.

In recent years, much research has focused on the potential health and environmental impacts of buckyballs and carbon nanotubes. Fullerenes have been shown to cause brain damage in fish and inhaling carbon nanotubes results in lung damage similar to that caused by asbestos.

“Buckyballs commonly form into clumps that could easily be inhaled by a person as dust particles,” Tieleman said. “How they enter cells and cause damage is still poorly understood but our model shows a possible mechanism for how this might occur.”

Source: University of Calgary