Dr. Alan Bowling, a University of Texas at Arlington assistant professor of mechanical and aerospace engineering, has proven that the effect of mass is important, can be measured, and has a significant impact on any calculations and measurements at the sub-micrometer scale.
Dr. Bowling’s findings facilitate better understanding of the movement of nano-sized objects in fluid environments that can be characterized by a low Reynolds number, which often occurs in biological systems. The unconventional results are consistent with Newton’s Second Law of Motion, a well-established law of physics, and imply that mass should be included in the dynamic model of these nano-systems. The most widely accepted models omit mass at that scale.
UTA assistant physics professor Samarendra Mohanty, and doctoral students Mahdi Haghshenas-Jaryani, Bryan Black, and Sarvenaz Ghaffari, as well as graduate student James Drake collaborated with Dr. Bowling to make the discovery.
A UT release notes that a key advantage of the new model discovered by the UTA research team is that it can be used to build computer simulations of nano-sized objects that have drastically reduced run times as compared to a conventional model based on Newton’s second law. These conventional models have run times of days, weeks, months and years while the new model requires only seconds or minutes to run.
In the past, researchers attempted to address the long run time by omitting the mass terms in the model. This resulted in faster run times but, paradoxically, violated Newton’s second law upon which the conventional model was based. The remedy for this paradox was to argue that mass was unimportant at the nano-scale.
However, the new model retains mass, and predicts unexpected motion of nano-sized objects in a fluid that has been experimentally observed. The new model also runs much faster than both the conventional and massless models.
It is expected that this new model will significantly accelerate research involving small-scale phenomena.
Research areas Dr. Bowling and his collaborators at UT Arlington are currently investigating include cell migration, protein function, bionic medical devices and nanoparticle suspensions for storing thermal energy. However, the applications for the computer simulation in medicine, biology, and other fields are endless.
The UTA research is detailed in a paper entitled: “Dynamics of Microscopic Objects in Optical Tweezers: Experimental Determination of Underdamped Regime and Numerical Simulation using Multiscale Analysis” (Nonlinear Dynamics DOI10.1007/s11071-013-1185-0), published online by the Journal of Non-Linear Dynamics. The paper, which is scheduled for publication in the journal’s print version later this year, presents new experimental observations and numerical simulations to investigate the dynamic behavior of micro–nano-sized objects under the influence of optical tweezers (OTs). OTs are scientific tools that can apply forces and moments to small particles using a focused laser beam. The motions of three polystyrene microspheres of different diameters, 1,950, 990, and 500 nm, are examined.
UTA College of Engineering dean Dr. Khosrow Behbehani observes in the release that the team’s findings may alter ways of thinking throughout the engineering and scientific worlds.
“The paper is only the beginning for this research,” Dr. Behbehani says. “I anticipate a high level of interest in the findings. It could transform the way we conduct research in nano-engineering by providing researchers with the ability to study such physical phenomena at such small scale through the model.”
The UTA research team used optical tweezers previously developed by Dr. Mohanty to measure oscillations that occur at the nano scale, thus proving that mass and acceleration must be considered at that level as well.
“We proved it in the lab,” says Dr. Bowling. “Publication in an accepted journal is the next step in gaining mass acceptance of the idea, which flies in the face of what most people believe now.”
The discovery resulted from a 2012 National Science Foundation grant project in which the UT Arlington team investigated a new model for how motor proteins behave in the body. The NSF award was funded through therapy Concept Grants for Exploratory Research, or EAGER program. The grants support exploratory work in its early stages on untested, but potentially transformative, research ideas or approaches.
Dr. Alan Bowling, is a native of El Paso and Austin, received his PhD from Stanford University, and was employed at the The Jet Propulsion Laboratory in Pasadena, CA, as a cooperative education student. He has industry experience obtained while with McDonnell Douglas Space Systems Company in Houston. Dr. Bowling also founded a company in Sunnyvale, CA which marketed a product he invented and patented, and his wide range of non-academic and academic experience has culminated in a research program focused on dynamics and controls, applied to problems in robotics and biomechanics.
Specifically, Dr. Bowling studies agility in the locomotion of limbed robots and biological systems. One of his main goals is the development of fast, agile, legged robots, a project for which he received a Career Award from the National Science Foundation. This work on agility is being applied to biological systems, including human, animal, and insect locomotion as well as cellular and molecular locomotion. He is interested in predicting injury and examining the performance limitations on biological systems imposed by potential injury. His current work involves the development of a dynamic model of motor proteins in order to better understand the physics behind the capabilities of nature’s motor. He is also interested in the development of autonomous systems at the macro, micro, and nano scales. The autonomous systems focus includes a broad range of topics including sensing, perception, manipulation, cognition, and human-robot interaction as well as other areas which need to be addressed in order to develop highly-capable, agile, adaptive, autonomous robots for applications including search and rescue, emergency medical response, and space exploration.
The University of Texas at Arlington is a comprehensive research institution of more than 33,300 students and 2,300 faculty members in the epicenter of North Texas. It is the second largest institution in the University of Texas System. Research expenditures reached almost $78 million last year. Visit http://www.uta.edu for more information.
The University of Texas at Arlington
The University of Texas at Arlington