Walking the Runway: Modeling New Trajectory Patterns of Chemical Agents

FORT BELVOIR, VA, UNITED STATES

04.29.2016

Courtesy Story

Defense Threat Reduction Agency's Chemical and Biological Technologies Department

Fort Belvoir, Va. Exposure to a chemical or biological agent poses serious risks to warfighters. Accurately modelling the trajectory patterns of chemical and biological warfare agents is critical to ensure the safety of our combat forces.

Projects by the Defense Threat Reduction Agency’s Joint Science and Technology Office are increasing warfighter safety by enhancing modeling capabilities of deadly chemical and biological agents. Understanding factors that influence the behavior of toxic chemicals and pathogens will influence the development of new countermeasures that could protect the warfighter and enable mission completion in environments compromised by these agents.

Existing knowledge regarding the molecular interaction between chemical and biological agents and the atmosphere or environmental surfaces is limited and presents a significant challenge to current modeling capabilities.

Quantitative structure-activity relationship (QSAR) models are only applicable to some volatile organic compounds. Those same models also lack highly sensitive qualitative and quantitative methods to characterize reactivity and predict efficacy and hazards when reaction rates are unknown. However, efforts within JSTO’s Basic Research Environmental Availability Program are leveraging innovative technologies and methodologies to reveal new information about the ways molecules interact and react in complex environments.

Recently a basic research project, managed by Dr. Brian Pate of JSTO and published in The Journal of Physical Chemistry A article, “Scattering Dynamics, Survival, and Dispersal of Dimethyl Methylphosphonate Interacting with the Surface of Multilayer Graphene,” highlighted the promising results.

Utilizing state-of-the-art gas surface interaction instrumentation and methods to characterize molecular exchanges with substrates, researchers demonstrated the efficacy of using kinetic energy controlled molecular beams to investigate the interactions of dimethyl methylphosphonate (DMMP), a nontoxic sarin simulant. DMMP has a well-defined surface (graphene) which improved the research team’s understanding of scattering dynamics. This breakthrough demonstrates the need to accurately model multiple bounce trajectories of the impinging molecules during the dispersal of chemical warfare agents in the environment.

In addition, Dr. Tony Esposito, Mike Roberts, Dale Taylor and Rick Fry are leading other environmentally focused JSTO efforts. These complementary projects include the prediction of physico-chemical properties using empirical QSAR methods and theoretical ab initio methods.

Useful molecular descriptors are needed to quantitatively predict specific reaction rate constants. A new collaborative effort between JSTO and the U.S. Army Edgewood Chemical and Biological Center is exploring environmental effects for chemical warfare simulants on relevant operational surfaces.

Developing highly sensitive qualitative and quantitative experimental methods that probe sticking coefficients and subsurface concentration gradients of contaminants will lead to the identification of new transport mechanisms.

This knowledge will enhance modeling tools that enable the prediction of technology efficacy and hazards for a range of known agents, materials, decontaminants and environmental conditions. It will also provide the capability to approximate the degradation chemistry for yet-to-be-characterized chemicals, leading to better protections for the warfighter.

POC: Dr. Brian Pate; [e-mail]

• Date Taken: 04.29.2016
• Date Posted: 04.29.2016 13:21
• Story ID: 196901
• Location: FORT BELVOIR, VA, US