Conferences, Lectures, & Seminars
Events for February
-
AME - Department Seminar
Wed, Feb 06, 2013 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Hai Wang , Professor Department of Aerospace & Mechanical Engineering University of Southern California
Talk Title: Nanoparticles - Transport Theory, Flame Synthesis and Selected Applications
Abstract: Synthesis of metal oxide nanoparticles in premixed stagnation flames offers significant advantages over other flame methods. Particles produced usually have good crystallinity, high phase purity, and narrow and controllable size distributions. Past studies have shown that when the stagnation surface is translated relative to the flame sheet, particle synthesis and film deposition can be achieved in a single step. The technique enables high-throughput film deposition and is scalable with respect to the deposition area. The first part of this talk will be on the stagnation flame technique for preparation of phase-pure titania nanoparticle films for applications in dye sensitized solar cells and for conductometric CO sensing.
It was recognized that a fine control of the particle property requires a rather precise knowledge about the time-temperature history of the particles behind the flame. Determined by the drag and thermophoretic forces acting on the growing cluster and nanoparticles, this history dictates the particle nucleation and size growth environment and time. This motivated us to re-examine the transport theories of nanoparticles in dilute gases. Through a gas-kinetic theory analysis, we obtained mathematical formulations for these forces in two limiting models of gas-particle interactions: specular and diffuse scattering. It has been shown that our expressions are more fundamental than the earlier Epstein expressions, and they offer the possibility of a unified description of particle transport, from molecules to cluster and nanoparticles. The origin of diffuse scattering has been explained by molecular dynamics. The remaining problem lies in a missing first-principle based description for the transition from elastic specular scattering to inelastic diffuse scattering at several nanometers of particle size, as will be discussed in detail.
More Info: http://ae-www.usc.edu/seminars/2-6-13-wang.shtml
Location: Seaver Science Library (SSL) - Room 150
Audiences: Everyone Is Invited
Contact: April Mundy
Event Link: http://ae-www.usc.edu/seminars/2-6-13-wang.shtml
-
AME - Department Seminar
Wed, Feb 13, 2013 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Janna Nawroth, Postdoctoral Researcher at the California Institute of Technology
Talk Title: How to Build a Jellyfish: Translating Biological Mechanisms for Fluid Transport to Engineered Materials
Abstract: Insights into biological mechanisms for fluid transport have the potential to advance technology for robotics and medical implants. A major challenge is to link structure to function, i.e., to understand and replicate the dynamic interactions between living cells, elastic substrates, and the fluid environment. My approach is to learn from the design of simple aquatic invertebrates that pump, filter, and mix fluid across a wide range flow regimes. In a proof-of-concept study I have reverse-engineered a juvenile jellyfish, a model system for muscle powered pumps at intermediate Reynolds numbers. Using an iterative optimization strategy, I identified key determinants of propulsive and feeding performance in jellyfish, including actuator layout, substrate elasticity, and body geometry, and translated them to tissue-engineered materials. Constructs were assembled by seeding rat cardiac muscle cells onto flow-optimized silicone bodies. Guided by microfabricated surface cues, the cells self-organized into a swimming muscle capable of synchronous contraction. Optimally designed constructs achieved propulsion and generated "feeding" currents quantitatively and qualitatively comparable to real jellyfish. I will summarize the design lessons learned in the process and discuss general implications for tissue-engineering and soft robotics.
Biography: Janna Nawroth completed her undergraduate studies in Molecular Biotechnology and Bioinformatics at the University of Heidelberg, Germany. Prior to joining the PhD program in biology at Caltech, she spent two years at the Yale school of Medicine conducting master's degree research in neuroscience. She received her PhD degree in 2012 from Caltech where she was co-advised by both John Dabiri at Caltech and Kit Parker at Harvard University while conducting cross-disciplinary research on design and fabrication of muscle-powered fluid pumps. She is currently a post-doctoral researcher in the Dabiri lab, working on neuronal control and fluid transport in marine invertebrates such as squid and jellyfish.
More Info: http://ae-www.usc.edu/seminars/2-13-13-Nawroth.shtml
Location: Seaver Science Library (SSL) - Room 150
Audiences: Everyone Is Invited
Contact: Jorge Castilla
Event Link: http://ae-www.usc.edu/seminars/2-13-13-Nawroth.shtml
-
AME - Department Seminar
Wed, Feb 27, 2013 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Eric Lauga , Associate Professor at the University of California, San Diego in the Department of Mechanical and Aerospace Engineering
Talk Title: Micron-Scale Carpets: The Optimal Hydrodynamics of Cilia
Abstract: The world of self-propelled low-Reynolds number swimmers is inhabited by a myriad of microorganisms such as bacteria, spermatozoa, ciliates, and plankton. In this talk, we focus on the locomotion of ciliated cells. Cilia are short slender whiplike appendages (a few microns long, one tenth of a micron wide) internally actuated by molecular motors (dyneins) which generate a distribution of bending moments along the cilium length and produce time-varying shape deformations. In most cases cilia are not found individually but instead in densely packed arrays on surfaces. In this talk we will ask the question: can the individual and collective dynamics of cilia on the surface of an individual microorganism be rationalized as the solution to an optimization problem? We first address the deformation of individual cilia anchored on surfaces before characterizing the locomotion and feeding by surface distortions of swimmers covered by cilia array. We demonstrate, as solution to the optimization procedure, the appearance of the well-known two-stroke kinematics of an individual cilium, as well as waves in cilia array reminiscent of experimentally-observed metachronal waves.
Host: Professor Kanso
More Info: http://ae-www.usc.edu/seminars/2-27-13-lauga.shtml
Location: Seaver Science Library (SSL) - Room 150
Audiences: Everyone Is Invited
Contact: April Mundy
Event Link: http://ae-www.usc.edu/seminars/2-27-13-lauga.shtml