When metal nanoparticles are excited by light resonant with the particle’s surface plasmon, non-radiative relaxation efficiently generates heat in the immediate region surrounding the particle. Such photothermal heating has been extensively explored in solution environments for applications such as cancer treatment and drug delivery. In contrast, use of and understanding of photothermal heating in solids, such as nanoparticle-polymer composites, has been limited. However, such photothermal effects could facilitate in situ thermal processing of polymeric materials via externally-controllable light excitation. The spatial specificity and temperatures achieved can potentially be used for triggering phase transitions, cross-linking, or driving region-specific chemical reactions inside the existing material. Anisotropic particles enable further tuning of the plasmonic frequency and polarization-controlled heating. By embedding fluorophores in the composite, a sensitive relative fluorescence approach can be utilized to dynamically monitor the average temperature within the sample as it is thermally processed. With modest light intensities and dilute nanoparticle concentrations, controllable temperature changes of several hundred degrees Celsius have been achieved.
Events Calendar View
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NanoSEC Seminar
Oct 19, 2012
Embedded Metal Nanoparticles as Light-Driven, Localized Heaters for in-situ Materials Processing
Guest: Laura Clarke, Department of Physics, NC State University
Friday, October 19, 2012 4:00 pm - 5:00 pm
Location: Riverbend Research South Laboratory Auditorium -
Observatory Open House
Oct 19, 2012
Observatory Open House
Friday, October 19, 2012 8:00 pm - 10:00 pm
Location: Physics Building Observatory 4th Floor -
CSP Lunch Seminar
Oct 23, 2012
Multiscale Modeling of Tumor Development
Guest: Yi Jiang, Georgia State University
Tuesday, October 23, 2012 12:30 pm - 1:30 pm
Location: CSP Conference Room (322) -
CSP Lunch Seminar
Oct 30, 2012
Molecular Dynamics Simulation of Polyelectrolyte Packaging in a Nanocavity
Guest: Qianqian Cao
Tuesday, October 30, 2012 12:30 pm - 1:30 pm
Location: CSP Conference Room (322) -
Departmental Colloquium
Nov 1, 2012
Strong Interaction and the Essence of Mass
Guest: Ralf Gothe, University of South Carolina
Thursday, November 1, 2012 4:00 pm - 5:00 pm
Location: 202All visible matter that surrounds us is made of atoms, i.e. electrons and nuclei, and the latter are made of nucleons, which finally are made of quarks and gluons. Contrary to the recent discussions in the news, the Higgs boson, or frequently called the God Particle, is not responsible for the generation of all mass. In fact, if it exists, it only generates the mass of the elementary quarks and electrons amounting to less than 2% of the total visible mass. Somewhat counter intuitively, the biggest part of the mass is not ab initio mass at all but energy, or more physically, the energy of the strong fields that bind the quarks into nucleons. The mass-energy equivalence, E=mc2, formulated by Einstein allows us to understand that the more than 98% of the weight you see when you step on a scale is nothing, or more precisely vacuum filled solely with field energy. How Quantum Chromodynamics (QCD) generates these strong fields, and hence most of the mass, is still an unsolved problem that can be uniquely addressed by experiments at the Thomas Jefferson National Accelerator Facility (JLab) in Virginia.
Pushing the idea of an electron microscope to higher and higher energies allows us to investigate nucleons and their excitations with higher and higher resolution via electron scattering experiments carried out at JLab. A close collaboration of theorists and experimentalists has already started to shed light on some of the remaining, overarching, and most important problems of QCD, as defined by Nuclear Science Advisory Committee’s Long-Range Plan, by providing new insights into the structure of the nucleon, the transition between meson/baryon and quark/gluon degrees of freedom, the nature of confinement, and the essence of mass. -
NanoSEC Seminar
Nov 2, 2012
Multiscale Material from Atom Modeling and Simulation to Continuum
Guest: Xianqiao Wang, College of Engineering, University of Georgia
Friday, November 2, 2012 4:00 pm - 5:00 pm
Location: Riverbend Research South Laboratory AuditoriumFor several decades continuum theory has been a dominating theoretical framework for the analysis of materials and structures. This approach to predict material deformation and failure, by implicitly averaging atomic scale dynamics and defect evolution spatially and temporally is valid only for large system. It is realized that as technologies extend to the nanometer range, continuum mechanics at this new arena is questionable. Whereas atomic-scale modeling and simulation methods, e.g., molecular dynamics (MD), have provided a wealth of information for nano systems by elucidating the atomistic mechanisms that govern deformation and rupture of chemical bonds, these methods can only handle problems limited in length/time scales. Yet, ultimately we aim at the design and manufacture of synthetic and hierarchical material systems or structures in which the organization is designed and controlled on length scales ranging from nano to micro, even all the way to macro. Therefore multiscale modeling, from atom to continuum, is inevitably needed.
This talk presents an atom-based continuum (ABC) theory coupling with thermal, mechanical and electrical mechanism, aiming at a seamless transition from the atomistic to the continuum description of multi-element crystalline solids (which has more than one kind of atom in the unit cell). By accounting for the upgraded Nosé-Hoover thermostat and Lorentz force, we put forth a novel way to appreciate the full benefit of coupling the thermal, mechanical and electromagnetic fields at nano/micro scale. Contrary to many multiscale approaches, ABC theory proposed here is naturally suitable for the multi-physics analysis of multi-element crystals. Taking both efficiency and accuracy into consideration, we adopt a cluster-based summation rule for atomic force calculations in the finite element formulations. When coarse mesh is used, the majority of the degrees of freedom can be eliminated, hence, the computational cost can be reduced, accompanying the decrease of the accuracy of the simulation results. When the finest mesh is used, any lattice site is a finite element node, and the model becomes identical to a full-blown MD model, which is the standard model manifesting the discrepancies or accuracies of others by comparisons. It is possible to envision that the use of this new method in support of diverse applications, ranging from the exploitations of critical physical phenomena such as crack extension, phase transformation, and dislocation initiation at nano scale to the energy harvesting and design of bone materials at micro scale.
Bio: Dr. Xianqiao Wang is currently an Assistant Professor of College of Engineering at University of Georgia. He received his B.S. and M.S. degree in engineering mechanics from Hunan University (China) in 2004 and 2007, respectively. He obtained his Ph.D. degree in mechanical engineering from the George Washington University in 2011. After graduation, he joined the Mechanical and Aerospace Engineering Department at the George Washington University as a Research Assistant Professor. His main research areas are multiscale material modeling and simulation, computational nanomechanics, biomechanics, coupled physics analyses of nanomaterials, microcontinuum field theory, energy harvesting, and material design.
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