| NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
| Recipient: |
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| Initial Amendment Date: | July 2, 2010 |
| Latest Amendment Date: | July 2, 2010 |
| Award Number: | 1033336 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Ruey-Hung Chen
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
| Start Date: | August 1, 2010 |
| End Date: | July 31, 2014 (Estimated) |
| Total Intended Award Amount: | $214,000.00 |
| Total Awarded Amount to Date: | $214,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
506 S WRIGHT ST URBANA IL US 61801-3620 (217)333-2187 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
506 S WRIGHT ST URBANA IL US 61801-3620 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | TTP-Thermal Transport Process |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
1033356
Cahill
Nanoscale objects, such as metal nanoparticles or carbon nanotubes, are prone to highly efficient absorption of electromagnetic radiation. When high intensity electromagnetic radiation is delivered to such objects, such as by a focused laser beam, the absorbed energy can lead to extreme local heating of and very large temperature increases in both the nanoscale objects and the surrounding medium. These highly localized thermal excursions correspond to heat fluxes that can be orders of magnitude larger than those sustained at the macroscale.
Intellectual Merit: This research builds upon advances in (a) laser-based ultrafast optical techniques capable of capturing relevant phenomena at pico- to nanosecond time scales and (b) computational power and modeling techniques allowing simultaneous examination of such systems experimentally and theoretically at the same temporal and special scales. In particular, molecular dynamics simulations and time resolved pump-probe experiments will advance the understanding of heat transfer, phase transformation, and phase equilibria arising at the interface between the nanoscale solids and a surrounding liquid.
Broader Impacts: The research focuses on the exchange of thermal energy between an intensely heated solid nanoparticles and a surrounding liquid. This has important implications for biomedical applications such as highly selective thermal therapy for cancer treatment. Graduate students engaged in the research will make contributions in heat transfer, materials science, soft-hard matter interactions, and phase equilibria. Undergraduate students will also be engaged in the research. Pertinent visual-learning and web-based tools will be developed to integrate the research and education activities.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The conduction of heat is a process that is familiar from everyday experience: a metal pipe feels cold because heat is conducted efficiently away from your skin and many people have experienced that a silver spoon quickly becomes too hot to hold when immersed into hot gravy boat at a Thanksgiving dinner. Because the conduction of heat is a random process described by diffusion, the rate at which a material exchanges heat scales as the square of the dimensions; in other words, if object is shrunk by a factor of 10, the rate of heat transfer accelerates by a factor of 100. In our project, Nanoscale Heat Transfer and Phase Transformation Surrounding Intensely Heated Nanoparticles, supported by the National Science Foundation, we studied the conduction of heat surrounding metal particles that are 10 nanometers in diameter. Since 10 nanometers is a factor of million smaller than a centimeter, the conduction of heat is accelerated by a factor of one trillion. So instead of heat flow occurring on a human time scale of 1 minute, we studied the heat flow of heat on a time-scale of 100 trillionths of a second (100 picoseconds). The experiments employ short pulses of light, with a duration of 1 picosecond, to abruptly heat nanometer-scale metal particles and probe how quickly the particles cool by the transfer of heat into their surroundings.
At these small scales, the conduction of heat becomes sensitive to how molecules and atoms interact with each other. The intellectual merit and main outcomes of our work were i) the development of techniques capable of resolving those differences in interactions; and ii) systematic measurements of heat conduction across interfaces between metal nanoparticles and surrounding materials. We found that the conduction of heat into an organic material is strongly suppressed compared to the conduction of heat into water. Our experimental results are consistent with the proposition that the strength of molecular interactions is a key predictor of the ability of heat to cross from one material into another.
While the outcomes of our project were to advance fundamental scientific understanding of heat, one broader impact of our work is on the design of experimental medical treatments that could precisely target structures within a cell for thermal destruction. The concept of these so-called “photothermal medical therapies” are to use metal nanoparticles and heating by short duration laser pulses to create high temperature excursion localized to structures within the cell. Advances in the fundamental science of the type developed in our work are needed to better predict the temperature excursions that will be produced by various combinations of nanoparticles, laser pulses, and environments of the nanoparticles within the cell.
Last Modified: 11/02/2014
Modified by: David G Cahill
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