MSEN Fall 2007 Seminar Schedule
| Date | Location | Speaker | Topic |
|---|---|---|---|
| 9/21/07 | CHEN 112 | Dr. Kayleen Helms | Trends and Challenges for Shrinking Electronic Packaging Features |
| 09/28/07 | CHEN 104 | Dr. Cris Schwartz | UHMWPE and Artificial Joints: What’s Next? |
| 10/05/07 | CHEN 104 | Mr. Amnaya Awasthi | Atomistic simulations of nanotubes and nanocomposites |
| 10/26/07 | CHEN 104 | Mr. Osman Anderoglu | Thermal Stability of Sputtered Cu Films with Nanoscale Growth Twins |
| 10/26/07 | CHEN 104 | Dr. Neil Everett | Quantum Dot-doped Microspheres for Sensing and Measuring Weak Interactions |
| 11/02/07 | CHEN 104 | Dr. Arumugam Manthiram | Enabling Materials for Electrochemical Energy Storage and Conversion |
| 11/09/07 | CHEN 104 | Dr. Raymundo Arroyave | To be announced |
| 10/27/06 | ENPH 301 | Dr. Evan Ma | to be announced |
| 11/30/07 | CHEN 102 | Dr. Long-Qing Chen | Pennsylvania State University |
| Dr. Kayleen Helms | |
|---|---|
| Research Engineer, Intel Corp. | Time: 4:00 to 5:00 p.m. |
| Trends and Challenges for Shrinking Electronic Packaging Features | |
| Back to top | |
| Dr. Cris Schwartz | |
| Department of Mechanical Engineering, TAMU Facutly, Materials Science and Engineering |
Time: 4:00 to 5:00 p.m. |
| UHMWPE and Artificial Joints: What's Next? | |
| The use of artificial joints for the treatment of degenerative diseases of the hip and knee is now commonplace. However, due to longer life expectancies and more active lifestyles in older citizens, there is a serious problem of patients living longer than their implants. There is a need to develop joints with higher durability than the commonly used design of ultra-high molecular weight polyethylene (UHMWPE) articulating against a metallic surface. In an effort to extend the lifetime of these implants, investigators have sought a thorough understanding of the interactions between the body and the implant. A description of the fundamental biological process that limits the lifetime of artificial joints will be presented. This talk will detail the evolution of total-joint replacement devices from the earliest approaches. The development of the Dual Axis Wear Simulator (DAWS) testing device will be discussed along with testing done with UHMWPE and other polymers to demonstrate the device’s capability to simulate in vivo wear processes. A number of currently used and proposed treatment of UHMWPE will be presented. Finally, some possibilities for promising future research will be presented in light of their potential benefits and technological feasibility to produce longer lasting artificial joints Back to top |
|
| Mr. Amnaya Awasthi | |
| MSEN student Department of Aerospace Engineering |
Time: 4:00 to 5:00 p.m. |
| Atomistic simulations of nanotubes and nanocomposites | |
| For nanosystems, capabilities to evaluate material behavior by experimental means are limited; therefore, theoretical alternatives are utilized. These techniques are based on the physics of interactions among individual atoms that constitute the nanosystem. This talk presents the evaluation of mechanical properties of carbon nanotubes and interfacial characteristics of composites containing carbon nanotubes, using atomistic simulations. In the first part of the talk, quantum mechanical(QM) simulations are performed to evaluate vibrational characteristics of single walled nanotubes. The information of natural frequencies and mode shapes obtained using the QM simulations is used to construct a discrete Newtonian spring-mass system. Appropriate boundary conditions are applied in a classical mechanics sense to evaluate the moduli in tension and torsion. Nanotubes of varying lengths are evaluated for their moduli using this procedure. In the second part of the talk, molecular dynamics (MD) simulations are performed to evaluate interfacial properties of nanotube composites. A suitably chosen polymer is introduced next to a graphene sheet, which resembles the carbon nanotube in physical morphology. The phases are separated in normal and shear modes to evaluate the force-displacement characteristics. Size dependence studies are performed to obtain limiting behavior of the response. This way, continuum level properties are obtained and a cohesive zone model is constructed for the interface which can be utilized in higher level micromechanical or finite element-based theoretical computations. Back to top |
|
| Mr. Osman Anderoglu |
|
MSEN student
Department of Mechanical Engineering |
Time: 3:30 to 4:30 p.m. |
| Thermal Stability of Sputtered Cu Films with Nanoscale Growth Twins | |
| We have investigated the thermal stability of sputter-deposited Cu thin films with high density of nanoscale growth twins by using high-vacuum annealing up to 800 °C for 1 hour. Average twin lamellae thickness increased gradually from approximately 4 nm for as-deposited films to slightly less than 20 nm after annealing at 800 °C. The average columnar grain size, on the other hand, increased rapidly from approximately 50 nm for as-deposited to 500 nm for Cu annealed at 800 °C. In spite of an order of magnitude increase in grain size, the annealed films retained a high hardness of 2.2 GPa, reduced from 3.5 GPa in the as-deposited state. The high hardness of the annealed films is interpreted in terms of the thermally stable nanotwinned structures. This study shows that nanostructures with a layered arrangement of low-angle coherent twin boundaries may exhibit better thermal stability than nanocrystals with high-angle grain boundaries. Back to top |
|
| Dr. Neil Everett |
|
| MSEN student Departments of Chemical and Mechanical Engineering |
Time: 3:30 to 4:30 p.m. |
| Quantum Dot-doped Microspheres for Measuring and Sensing Weak Interactions |
|
| Evanescent wave-excited luminescence from quantum dot-modified microspheres (both polymeric and silica based) can be used for directly measuring very weak surface interactions. This method, developed in our lab, involves the use of video (VM) and total internal reflection microscopies (TIRM) to simultaneously monitor the 3D trajectories of an ensemble of microspheres diffusing above a wall. By interpreting the luminescence data using inverse statistical mechanical analyses, we are able to obtain separation-dependent potential energy profiles for individual particles interacting with the underlying substrate. Moreover, we achieve nanometer-scale spatial resolution while directly measuring potential energy on the order of kT and surface forces with a sensitivity in the range of femtonewtons (10‑15 N). A detailed study of the quantum dot-doped particles with flow cytometry, confocal microscopy, spectrofluoremetry, and temporal measurements of luminescence intensities provide supplemental evidence that these functionalized probes can be used effectively for a variety of experiments. This approach could, for instance, enable measurements of multiple specific biomolecular interactions via spectral multiplexing or enhance morphology-dependent resonance modes in sensing platforms Back to top |
|
| Dr. Arumugam Manthiram | |
| Materials Science and Engineering University of Texas |
Time: 3:30 to 4:30 p.m. |
Enabling Materials for Electrochemical Energy Storage and Conversion |
|
Electrochemical energy storage and conversion technologies such as lithium ion batteries and fuel cells are attractive for a variety of energy needs ranging from portable devices to automobiles to stationary power. Although lithium ion batteries have revolutionized the portable electronics market, their adoption for hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV) is hampered by high cost, safety concerns, and limited energy and power capabilities. After focusing briefly on a fundamental understanding of the factors that control the electrochemical performances of lithium ion battery cathodes, this presentation will concentrate on the development of high energy density layered oxide cathodes and high power spinel oxyfluoride cathodes for lithium ion batteries. Similarly, the fuel cell technologies are hampered by high cost, durability, and operability problems, which are linked to severe materials challenges. For example, the high cost of the platinum catalyst, limited operating temperature (< 100 oC) of the polymeric Nafion membrane, and catalyst and membrane degradation during long-term operation pose serious problems. This presentation will focus on the development of low-cost, nanostructured palladium-based alloy catalysts and polymeric blend membranes based on acid-base interactions to overcome some of these difficulties. |
|
| Dr. Raymundo Arroyave | |
| Materials Science and Engineering Faculty Department of Mechanical Engineering Texas A&M University |
Time: 3:30 to 4:30 p.m. |
Application of Density Functional Theory Methods to the Prediction of Thermodynamic, Structural, and Kinetic Properties of Metallic Systems |
|
Depending on the length and time scale as well as the physical process to model, there is a wide variety of computational tools available to model the behavior of materials, ranging from calculations at the electronic structure level to the continuum. In this talk, I will present a brief overview on the use of methods based on density functional theory (DFT), to predict the thermodynamic, structural and kinetic properties of materials. It will be illustrated how the coupling of lattice dynamics to DFT can be used to predict thermodynamic/structural properties of metallic systems of interest at finite temperatures. Additionally, very recent progress in the prediction of diffusion coefficients in metals through the combination of DFT and transition state theory will be presented. Finally, I will talk about how other researchers/groups are using these predictions to obtain more quantitatively accurate descriptions of the behavior of materials at the mesoscopic levels. |
Dr. Evan Ma |
| Johns Hopkins University | Time: 10:00 to11:00 p.m. |
| Atomic Structure and Plastic Deformation of Amorphous Metals | |
| The metals and alloys we are familiar with are all crystalline. The recent advent of bulk metallic glasses (BMGs) presents exciting opportunities. A major challenge in establishing the structure - property relationships for these amorphous metals is to understand how plasticity is mediated in the absence of dislocations. In this talk, we will present our recent progress in addressing such materials science issues of these non-crystalline metals. We will briefly explain the processing, structure, phase transformations, and mechanical properties of BMGs. Our focus, however, will be on the atomic-level structure including short-to-medium range order and polyamorphism, and on the plastic low observed in amorphous metals. Back to top |
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| Long-Qing Chen, Ph.D. | |
| The Pennsylvania State University | Time: 4:00 to 5:00 p.m. |
| Phase Transitions and Domain Structures in Ferroelectric Thin Films | |
| This presentation will discuss the applications of thermodynamic theories and phase-field method to predicting phase transitions, domain structures and switching in nanoferroelectrics. The emphasis is on the role of strain in the phase transition temperatures, domain stability, and switching and piezoelectric responses of in ferroelectric thin films and islands under an external electrical field. Examples to be discussed include several important oxide systems, PbTiO3, BaTiO3, SrTiO3, PbZrxTi1-xO3, BiFeO3 and superlattices. It is shown that ferroelectric transition temperatures in thin films can be shifted by hundreds of degrees as compared to the corresponding bulk crystals. It is also demonstrated that strain can drastically modify the domain structures of a thin film as well as its properties such as coercive field, spontaneous polarization, dielectric constant and piezoelectric responses. Examples of domain stability diagrams, stability as a function of temperature and strain, will be presented, which can potentially provide guidance for achieving desirable ferroelectric properties by choosing appropriate substrate and growth temperature of thin films. Back to top |
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