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2005-2006 HIGHLIGHTS








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Yuriy Roman-Leshkov, James Dumesic, and Juben Chheda

Chemical and Biological Engineering

Diesel fuel and industrial chemicals from simple sugar

The trend toward higher prices for oil and natural gas has sparked a race to make transportation fuels from plants instead of petroleum. It also has fueled a search for compounds, or chemical intermediates, that are the raw material for many modern plastics, drugs and fuels. Industry uses millions of tons of chemical intermediates, which are largely sourced from petroleum or natural gas.

Steenbock Professor James Dumesic (center) and his graduate students Yuriy Roman-Leshkov (left) and Juben Chheda (right) developed a better way to make a chemical intermediate called HMF (hydroxymethylfurfural) from fructose—fruit sugar. HMF can be converted into plastics, diesel-fuel additive, or even diesel fuel itself, but is seldom used because it is costly to make.

“Instead of using the ancient solar energy locked up in fossil fuels, we are trying to take advantage of the carbon dioxide and modern solar energy that crop plants pick up,” says Dumesic.

Dumesic’s research on environmentally friendly sources of common chemicals is supported by the U.S. Department of Agriculture and the National Science Foundation.

The new, patent-pending method for making HMF is a balancing act of chemistry, pressure, temperature and reactor design. After a catalyst converts fructose into HMF, the HMF moves to a solvent that carries it to a separate location, where the HMF is extracted. Although other researchers had previously converted fructose into HMF, Dumesic’s research group made a series of improvements that raised the HMF output, and also made the HMF easier to extract.

Material assembles into novel 3-D nanostructure

An international team of scientists affiliated with the University of Wisconsin Nanoscale Science and Engineering Center has coaxed a self-assembling material into forming never-before-seen, three-dimensional nanoscale structures, with potential applications ranging from catalysis and chemical separations to semiconductor manufacturing.

Led by Professors Paul Nealey and Juan de Pablo and colleagues at Georg-August University in Germany and the Paul Scherrer Institute in Switzerland, the team discovered that materials known as block copolymers will spontaneously assemble into intricate 3-D shapes when deposited onto particular 2-D surface patterns created with photolithography.

The result demonstrates a promising strategy for building complex 3-D nanostructures by using standard tools of the semiconductor industry, says Nealey. Those tools, particularly lithography, already allow the making of devices with dimensions substantially smaller than 100 nanometers, or one hundred-thousandth of a centimeter.

But photolithography is also limited, he says, because as practiced today it is essentially a two-dimensional process. “What we’ve done by using self-assembling block copolymers is to extend photolithography to three dimensions,” says Nealey. “And the structures we’ve fabricated are completely different from the same block copolymer materials in the bulk.”

Also important to manufacturing is that the new 3-D nanostructures are stable, well defined and nearly defect-free over large areas. They also align perfectly with the underlying lithographic pattern—a key requirement for any device or application based on them.

Promise shown in controlling embryonic stem cells

Liquid crystals, the same phase-shifting materials used to display information on cell phones, monitors and other electronic equipment, can also be used to report in real time on the differentiation of embryonic stem cells.

Differentiation is the process by which embryonic stem cells gradually turn into function-specific types of adult cells, or so-called “cell lineages,” including skin, heart or brain.

The main challenge facing stem cell research is that of guiding differentiation along these well-defined, controlled lineages. Stem cells grown in the laboratory tend to differentiate in an uncontrolled manner, resulting in a mixture of cells of little medical use.

Now, UW-Madison researchers at the NSF-funded Materials Research Science and Engineering Center have shown that by mechanically straining the cells as they grow, it is possible to reduce significantly and almost eliminate the uncontrolled differentiation of stem cells.

A liquid crystal-based cell-culture system promises new ways of achieving real-time control over interactions between synthetic materials and human embryonic stem cells, including the possibility of straining embryonic stem cells as they grow.

“Differentiated cells appear to be much more spread and appear to exert different levels of force on the matrix in which they are grown,” says Assistant Professor Sean Palecek. “That force can be read to a liquid crystal. Through simple changes of liquid crystal texture and color, our cell culture system is able to report, in real time, the cell interactions with the underlying support on which they are grown.”

In addition to Palecek, the team includes Professors Juan de Pabloand Nicholas Abbott and former postdoctoral researcher Nathan Lockwood, graduate student Jeff Mohr, researcher Lin Ji, and School of Veterinary Medicine (ophthalmology) and Biomedical Engineering Professor Christopher Murphy.

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