Old riddle: What has four wheels and flies? Answer: a garbage truck.

Here's another, modern answer. Ecobot II, a rolling, autonomous robot built at the University of the West of England, in Bristol, employs a microbial fuel cell to extract energy from rotten apples or dead flies.

A chemical reaction takes place in an artificial digester, according to Chris Melhuish, director of the university's Intelligent Autonomous Systems Laboratory. The reaction produces a small amount of electricity—in the microwatt range, Melhuish said—but enough that it can be accumulated and then expended in useful work.

One of eight microbial fuel cells connected in series that Ecobot II uses to make electricity.

In this manner, Ecobot II moves a few centimeters every 10 minutes or so. Meanwhile, it measures temperatures and relays them continually to a receiver in the lab from up to 30 meters away.

The researchers wanted to prove that autonomous robots, set loose in organic environments, could fend for themselves.

Its microbial fuel cell mixes microbes, food, and a mediator (sludge, in this case) on the anode side of a proton exchange membrane. The bugs produce an enzyme to break down the food into glucose. They also generate electrons as part of their metabolic cycle. A mediator collects these electrons and dispatches them to the anode and on to the circuitry.

"The system trades energy for time," Melhuish explained.

The fuel cell falls short of the energy density of an AA alkaline battery—about 604 joules per gram. The MFC's energy density is a mere 1.33 J/g. But, the microbial fuel cell can make electricity for as long as the microbes remain alive, which could be years, Melhuish said.

The wind loads for the World Trade Center's two towers met and surpassed New York City building codes when they were built and when they were destroyed, according to the National Institute of Standards and Technology.

Wind-load capacity is a key to determining the overall strength of a tall building. It gives engineers an idea of the building's capability not only to withstand high winds, but also to weather unanticipated events such as major fire or impact damage.

NIST, in Gaithersburg, Md., is studying the World Trade Center's construction as part of an overall building and fire safety investigation into the towers and the disaster that felled them.

To assess the overall strength and performance of the two buildings before they were brought down by the terror attacks, investigators first looked at the wind loads the structures were designed to resist. They reviewed the original 1960s-era documents, which included wind-tunnel test data and the method engineers used to determine how much wind load the towers could withstand. The towers were designed in 1968.

When NIST researchers ran their own calculations of wind load, they came up with slightly different values from those used in the design of the buildings. Although the new wind loads differed from those noted in the original design, the towers exceeded all requirements established in the New York City building codes from 1968 to 2001. Performance was also better than required by many other building codes of the era, according to NIST.

The NIST investigation team's final report is scheduled for release as a draft document this month.

The National Science Foundation awarded a $2 million, five-year grant to Virginia Polytechnic Institute and State University's College of Engineering in Blacksburg to expand the school's mentoring and retention programs. Currently, the university's College of Engineering has a retention rate among freshmen of 78 percent, according to Bevlee Watford, associate dean for academic affairs at the engineering school. It hopes to raise that to 85 percent.

The majority of dropouts occur during the transition from the freshman to the sophomore year, Watford said.

Virginia Tech's College of Engineering will use the grant money to bolster three existing programs that have been targeted to women and minorities, two groups that have historically been under-represented, Watford said. Current support programs will be expanded. Incoming freshmen will be offered introductory math and chemistry courses and mentoring services during the summer before they enter the school. Mentoring services traditionally offered to female and minority students will also be made available to all students. About 5,600 undergraduates are currently enrolled in the College of Engineering.

The American Precision Museum added four new members to its Machine Tool Hall of Fame: Thomas Blanchard (1788-1864), inventor of the copy lathe; Ebenezer G. Lamson (1814-1891), founder of Jones & Lamson Machine Co.; Robert M. Gaylord (1888-1980), president of Ingersoll Milling for 40 years; and Leighton A. Wilkie (1900-1993), inventor of the metal band saw. The Windsor, Vt., museum is an ASME Heritage Collection. It houses one of the nation's largest collections of machine tools.

ThinGap Corp. of Ventura, Calif., has received a $750,000 Phase II Small Business Innovation Research contract from the Defense Advanced Research Projects Agency to develop a wheel hub drive motor for unmanned ground electric-drive vehicles. ThinGap motors use machined copper sheets in place of the magnet wires and iron cores of conventional motors. DARPA's Grand Challenge involves autonomous ground vehicles.

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