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Defusing Explosive Situations

Defusing Explosive Situations
Chemisty Professor Jonathan Sessler's laboratory is working with a class of molecules that would detect small amounts of TNT and rapidly change color, signaling the presence of the explosive.

Chemisty Professor Jonathan Sessler's laboratory is working with a class of molecules that would detect small amounts of TNT and rapidly change color, signaling the presence of the explosive.
Improvised explosive devices (IEDs) have been a devastating weapon against United States armed forces in Iraq and Afghanistan.

There have been more than 81,000 IED attacks in Iraq, which have accounted for about two-thirds of the American combat deaths. They have caused an even higher percentage of wounds.

For Iraqis, IEDs have caused an estimated 11,000 civilian casualties and more than 600 deaths among security forces.

Such weapons are cheap and easy to make, easy to hide and easy to detonate remotely. Those factors make them an ever-present danger in conflicts to come.

Several faculty members from a range of disciplines at The University of Texas at Austin have found ways to adapt their ongoing research to investigate ways to deal with IEDs.

    • Jonathan Sessler, a chemistry professor, is working on ways to detect molecules of explosives used in IEDs and similar weapons. The result could be to make detectors sensitive enough to tell whether an object is a bomb.


    • Hao Ling, an electrical and computer engineering professor, is developing algorithms that would, ultimately, result in using radar signals to reveal what people inside a building are doing. Are they going through the motions of making a bomb or dinner?


    • Sam Gosling, an associate psychology professor, is studying the personalities of military working dogs to develop ways to determine which have the best temperaments for working as bomb sniffers.

The National Science Foundation (NSF) is funding the projects with a total of $1.1 million. Overall, the NSF's 2007 budget allocated $20 million for basic research on explosives and related threats. It has funded 47 grants for 41 projects. (Some projects involve lead researchers at more than one university.)

The Department of Homeland Security's Science and Technology office has provided about $1 million for investment in grants resulting from NSF's explosives research.

While some government agencies are working on immediate remedies to IEDs, the NSF-sponsored research is more about the basics than quick deployment.

"The way I see it, we are not looking for some sort of immediate solutions," Ling said. "Our goal going into this is not to build the hardware to do this, but to take a step back and ask, 'What is the basic science? What is the art of the possible in monitoring people using radar?'"

IEDs are considered a continuing threat because their makers are staying a step ahead of solutions developed by the U.S. military.

"Insurgents have shown a cycle of adaptation that is short relative to the ability of U.S. forces to develop and field IED countermeasures," according to a National Academy of Sciences paper, "Countering the Threat of Improvised Explosive Devices: Basic Research Opportunities."

"The gap between offense and defense in this particular area is greater than in most other military endeavors," Sessler said. "I'd like to address that disparity, make the balance a little bit more fair."


Sessler has long recognized the problems that people with bad intentions and some chemicals can cause.

"Ever since I was an exchange student in Israel in the 1970s, I've been aware that it's not hard for a bad guy to go cook up some explosives," said Sessler, the Roland K. Pettit Centennial Professor in the Department of Chemistry and Biochemistry.

In his lab, Sessler and his students are trying to find compounds that are sensitive enough to detect molecules of explosives in small amounts and show that explosives have been found by changing color.

"Our approach is based on finding molecules that will change their (molecular) shape dramatically and as a result, change their color when exposed to explosives," he said. "The challenge is to enhance the effect and to find systems that are relatively specific for the kinds of explosives that might be in IEDs."

The lab is working with a class of molecules called tetrathiafulvalene (TTF). In collaboration with a group from the University of South Denmark, group members are trying to tune TTF and incorporate it into a class of bowl-like molecules called calixpyrroles to produce systems that capture explosive materials such as TNT. The molecular-scale capture would result in a change in color, signifying the presence of explosives.

In another approach, the lab is working with molecules that would stack with TNT to reach the state of a liquid crystal.

"When you add TNT to this it tends to stack up with a big disc-like molecule in the middle interacting with TNT. You get very pretty colors," Sessler said. "This molecule is big so it's absorbing energy, light."

Kent Nielsen, a visiting student from Denmark, recently produced a prototype TTF-calixpyrrole system that changes from yellow to green when exposed to TNT or similar molecules, such as trinitrobenzene.

University of Texas at Austin graduate student Jung Su Park is modifying the TTF core and changing the size of the calixpyrrole receptor to see if greater interactions can be achieved and whether the extent of the color change can be increased.

Sessler said several devices could result from the lab's work.

One would be a scanner used at building entrances. It would monitor people and their belongings for traces of explosives and alert officials when it detected an explosive.

Another possibility is a squirt-gun type device that could be used to spray a suspicious package from a safe distance. Colors would change if there were explosives in the package.


In his lab in the Department of Electrical and Computer Engineering, Ling, the L. B. (Preach) Meaders Professor in Engineering, and his team are developing algorithms that would use radar to detect human activities inside an enclosed space, such as inside a building.

Ling's work on the NSF grant builds on a similar project he worked on for the Department of Defense's Defense Advanced Research Projects Agency.

"What we've been doing for the past three or four years is monitoring humans using radar," Ling said. "We have developed radar hardware to try to track people inside buildings."

For the NSF program, his lab is working on algorithms that would convert the radar signals to virtual renderings similar to that of a video game.

"What we want to do in this project is to first understand some of the basic physics of how radar waves interact with humans," he said. "In other words, how human movements are manifested in radar data."

People are used to seeing airplanes as blips on a radar screen.

That's fine as long as that's all the operator needs to see.

Those looking inside buildings for people making bombs need more detailed information.

So in his lab, Ling and his students are collecting radar data of people engaged in different activities such as walking and crawling on all fours.

Each movement of the person has a unique radar signature called the micro-Doppler. The arms and legs move more and move faster than the torso, which is reflected in the radar signals.

"A human has very complex motion dynamics so these subtle, minute movements translate into interesting micro-Doppler features," he says.

Then, using micro-Doppler, the researchers hope to extract much more information from a radar signal than is seen when a plane is a blip on a radar screen.

Eventually, the technology could end up in a device that could be mounted on a vehicle and would monitor activities in a building as it traveled down a street. Presumably, the device would be used to target specific streets where bomb makers are suspected of working.


It might be the research of Gosling, in the Department of Psychology, that has the most immediate impact on dealing with IEDs.

His NSF project will try to find out what personality traits make military working dogs-the ones that sniff for bombs in combat, shipping containers and other situations-best suited to finding explosives in the field.

The dogs are mostly the Belgian Malinois breed, which resemble German Shepherds.The American Kennel Club describes the Malinois as a "well balanced, square dog, elegant in appearance with an exceedingly proud carriage of the head and neck. The dog is strong, agile, well muscled, alert and full of life."

In his years of researching animal personalities, Gosling has found that matters of temperament-for example, how a dog reacts to stressful situations-is more important than having the most sensitive nose in how well it performs.

Temperament assessments are not now part of the selection and training process for military working dogs.

With the NSF grant, Gosling is working to find out what traits give a dog a good temperament in three dog-training groups at Lackland Air Force Base in San Antonio. He is working with Dr. Stewart Hilliard, chief of the Military Working Dog Training Course and Military Working Dog Evaluations at the 341st regiment.

Three traits that Gosling thinks are important to a good temperament are boldness or braveness, resilience (bouncing back quickly after a stressful situation) and motivation.

Whether they are important or there are other traits that are more so should be revealed by the research, Gosling said.

The project will work with the three groups of dogs as they are selected, trained and sent into the field.

Gosling said changes can be made to the training process according to the research findings, as needed.

"Our goal is to say here are the tests you need to have and here are the scores you need to look for," Gosling said. "They give us the best chance of identifying good dogs rapidly and effectively."

When he started researching animal personalities, some observers thought the subject a bit light. The military working dog work is anything but.

"It's a good demonstration of how research which may seem frivolous on the surface can yield some incredibly important and impactful results, saving lives," Gosling said. "When I first started studying animal personality I had no idea I would end up doing this."

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Monday, 15 August 2022

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