NSF grants boost homeland research

A series of 14 new grants from the National Science Foundation (NSF) have been awarded to support research related to the terrorism and anthrax events of fall 2001 and will contribute to homeland security objectives.

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by Valerie C. Coffey

A series of 14 new grants from the National Science Foundation (NSF) have been awarded to support research related to the terrorism and anthrax events of fall 2001 and will contribute to homeland security objectives. Two university-based teams will use the federal funds for photonics-based research in detection and decontamination of biological or chemical warfare agents.

Water pollution study
Marc Parlange and Joseph Katz of Johns Hopkins University (Baltimore, MD) received an estimated $100,000 for a one-year study of water pollution and trace contaminants from the World Trade Center (WTC) site through the deployment of instrumentation to measure the emission and resuspension of particles into the atmosphere. Over a period of ten days, the study will measure the flux and extent of particles from the WTC site and surrounding area. A combination of turbulence sensors, including particle image velocimetry (PIV), holographic PIV, and sonic anemometers mounted on a telescopic profiling tower will continually measure the shear stress, concentration, and flux profiles of particles from the surface up to 10 m above the site (see figure).

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Plant-scale experimental study in wind tunnel and field measures pollen in vertical flux using two-dimensional PIV. A holographic camera measures three-dimensional pollen distribution. The NSF grant will use the same instruments to study particle distribution in the area of the World Trade Center.
Click here to enlarge image

Particle image velocimetry measures fluid velocity fields by calculating the displacement of "tracer" particles injected into the fluid of interest. A high-speed light source, usually a pulsed laser, illuminates the particles while a cooled CCD camera images the particles. Correlation-algorithm software calculates the mean displacement of the particles between exposures. Division of the displacement by the time delay between the laser pulses returns the velocity field of the fluid.

A scanning-elastic lidar system will be deployed to measure at 1.5-m resolution the relative concentration of particles in the lower atmosphere (range up to 7 km.). The lidar system will be calibrated using the concentration measurements obtained from the PIV systems. An analysis of the field data will identify relationships between weather conditions (such as wind-shear stress and sensible heat flux), the magnitude of the surface flux of particles, and the extent of the transport into the atmosphere.

Irradiation as disinfectant
In a second award, Ernest Blatchley and Arthur I. Aronson of Purdue University (West Lafayette, IN) received more than $95,000 to investigate the feasibility and limitations of Bacillus anthracis decontamination processes using ultraviolet (UV) and gamma irradiation as physical disinfectants. Specifically, the goal of the project is to build a database of the sterilization characterisitics of B. anthracis spores in response to UV and gamma irradiation, noting the spore inactivation, repair, and mutation. The one-year project will also quantify dose delivery in decontamination systems and examine applications to water, air, and different types of surfaces.

"Ultraviolet has the potential to be fairly effective for eliminating bacteria on hard surfaces," says Blatchley, "but gamma can penetrate further into surfaces such as paper, which means it can decontaminate packages."

Using a conventional UV low-pressure mercury arc lamp (with an intensity of 100 mW/cm2), the starting dose of UV irradiation in the control lab setting would be approximately 20 mJ/cm2, says Blatchley. The experiment will start with the most basic lab conditions and contribute to an understanding of more complex real-world settings involving moving fluid and nonuniform spatial dimension. The gamma-based work utilizes a cobalt (Co60) source.

Both gamma and UV are very effective disinfectants that cause very little chemical change when used to sterilize a water supply, says Blatchley. But gamma-based decontamination can actually produce fewer unwanted byproducts than UV, he says. "Most people think that gamma is more dangerous because it is ionizing radiation, but as long as it doesn't come into direct contact with people, it can be a better disinfecting source than UV for these types of applications."

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