Saturday 25 January 2014

UT Arlington Research Team Proves Mass Is Important At The Nano-scale, Matters In Calculations And Measurements

Dr. Alan Bowling (In Attached Photo), 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.

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