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Articles 1 - 9 of 9

Full-Text Articles in Nanoscience and Nanotechnology

Method To Generate Surfaces With Desired Roughness Parameters, Yilei Zhang, Sriram Sundararajan Jul 2007

Method To Generate Surfaces With Desired Roughness Parameters, Yilei Zhang, Sriram Sundararajan

Mechanical Engineering Publications

A surface engineering method based on the electrostatic deposition of microparticles and dry etching is described and shown to be able to independently tune both amplitude and spatial roughness parameters of the final surface. Statistical models were developed to connect process variables to the amplitude parameters (center line average and root-mean-square) and a spatial parameter (autocorrelation length) of the final surfaces. Process variables include particle coverage, which affects both amplitude and spatial roughness parameters, particle size, which affects only spatial parameters, and etch depth, which affects only amplitude parameters. Correlations between experimental data and model predictions are discussed.


Atomic Force Microscope Imaging Of Dna And Multi Walled Carbon Nanotubes, Jacob Hohnbaum May 2007

Atomic Force Microscope Imaging Of Dna And Multi Walled Carbon Nanotubes, Jacob Hohnbaum

Mechanical Engineering Undergraduate Honors Theses

The Micro and Nano System Laboratory at the University of Arkansas currently is equipped with an Atomic Force Microscope (AFM). This device can be used to measure objects with resolution on the nanometer scale, but there are a number of technical difficulties in performing scans of carbon nanotubes and DNA. The goal of this research is to successfully perform scans on both carbon nanotubes and DNA and to also establish laboratory processing protocols to re-perform such scans in the future. Previous works performed by other researchers in the laboratory provided basic protocols with which to begin the present research. These ...


A Fully Lagrangian Numerical Method For Calculating The Dynamics Of Oscillating Micro And Nanoscale Objects Immersed In Fluid, Nicole N. Hashemi, Mark Paul, Javier Alcazar, Raul Radovitzky Jan 2007

A Fully Lagrangian Numerical Method For Calculating The Dynamics Of Oscillating Micro And Nanoscale Objects Immersed In Fluid, Nicole N. Hashemi, Mark Paul, Javier Alcazar, Raul Radovitzky

Nastaran Hashemi

Many micro and nano-technologies rely upon the complicated motion of objects immersed in a viscous fluid. It is often the case that for such problems analytical theory is not available to quantitatively describe and predict the device dynamics. In addition, the numerical simulation of such devices involves moving boundaries and use of the standard Eulerian computational approaches are often difficult to implement. In order to address this problem we use and validate a fully Lagrangian finite element approach that treats the moving boundaries in a natural manner. We validate the method for use in calculating the dynamics of oscillating objects ...


Modeling Redox-Based Magnetohydrodynamics In Three-Dimensional Microfluidic Channels, Hussameddine S. Kabbani, Aihua Wang, Xiaobing Luo, Shizhi Qian Jan 2007

Modeling Redox-Based Magnetohydrodynamics In Three-Dimensional Microfluidic Channels, Hussameddine S. Kabbani, Aihua Wang, Xiaobing Luo, Shizhi Qian

Mechanical Engineering Faculty Publications

RedOx-based magnetohydrodynamic MHD[1] flows in three-dimensional microfluidic channels are investigated theoretically with a coupled mathematical model consisting of the Nernst-Planck equations for the concentrations of ionic species, the local electroneutrality condition for the electric potential, and the Navier-Stokes equations for the flow field. A potential difference is externally applied across two planar electrodes positioned along the opposing walls of a microchannel that is filled with a dilute RedOx electrolyte solution, and a Faradaic current transmitted through the solution results. The entire device is positioned under a magnetic field which can be provided by either a permanent magnet or an ...


Origin Of Photomultiplication In C60 Based Devices, Jinsong Huang, Yang Yang Jan 2007

Origin Of Photomultiplication In C60 Based Devices, Jinsong Huang, Yang Yang

Mechanical & Materials Engineering Faculty Publications

In this manuscript, the origin of the photomultiplication effect was studied in C60 based devices by evaluating the wavelength dependent external and internal quantum efficiencies under various biases. The effect of materials with disordered structures on the photomultiplication effect was determined by intentionally integrating both ordered and disordered material structures into one organic solar cell device with a configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/pentacene/C60 fullerene/bathocuproine (BCP)/Al. Our results show that both the disordered structure of C60 and the charge trapping effect at the C60 /PEDOT:PSS ...


Improved Hole-Injection Contact For Top-Emitting Polymeric Diodes, Juo-Hao Li, Jinsong Huang, Yang Yang Jan 2007

Improved Hole-Injection Contact For Top-Emitting Polymeric Diodes, Juo-Hao Li, Jinsong Huang, Yang Yang

Mechanical & Materials Engineering Faculty Publications

In this letter, an efficient hole-injection contact was achieved for the top-emitting polymeric light-emitting diodes (PLEDs). The anode has a structure of metal/molybdenum oxide/ poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). It has been found that hole injection was significantly improved by inserting a thin layer of MoO3 between aluminum and PEDOT:PSS. An ultraviolet photoelectron spectroscopy (UPS) was used to investigate the change of work function, and photovoltaic measurement confirmed that the improved hole injection is due to the reduction of barrier height, resulted from the addition of transition metal oxide. PEDOT:PSS layer was found necessary ...


Deck-Mounted Steel Post Barrier System, John D. Reid, Ronald K. Faller, Jason A. Hascall Jan 2007

Deck-Mounted Steel Post Barrier System, John D. Reid, Ronald K. Faller, Jason A. Hascall

Mechanical & Materials Engineering Faculty Publications

An existing mountable safety barrier system, previously crash tested successfully on a wood bridge deck, was evaluated for use on a fiber reinforced plastic (FRP) bridge deck. In an attempt to avoid expensive full-scale crash testing, components of the existing system were evaluated using worst case conditions on two dynamic bogie crash tests and a series of computer simulations using nonlinear finite-element analysis. Simulation results closely approximated the physical results, with both displaying similar deformation, damage, and force levels. Both testing and simulation demonstrated that the barrier should function sufficiently if used on the FRP deck system. Further, the development ...


Regional Mechanical Properties And Stress Analysis Of The Human Anterior Lens Capsule, Ryan M. Pedrigi, G. David, J. Dziezyc, J. D. Humphrey Jan 2007

Regional Mechanical Properties And Stress Analysis Of The Human Anterior Lens Capsule, Ryan M. Pedrigi, G. David, J. Dziezyc, J. D. Humphrey

Mechanical & Materials Engineering Faculty Publications

The lens capsule of the eye functions, in part, as a deformable support through which the ciliary body applies tractions that can alter lens curvature and corresponding refractive power during the process of accommodation. Although it has long been recognized that characterization of the mechanical properties of the lens capsule is fundamental to understanding this physiologic process as well as clinical interventions, prior data have been limited by one-dimensional testing of excised specimens despite the existence of multiaxial loading in vivo. In this paper, we employ a novel experimental approach to study in situ the regional, multiaxial mechanical behavior of ...


Low Voltage And Fast Speed All-Polymeric Optocouplers, Yan Yao, Hsiang-Yu Chen, Jinsong Huang, Yang Yang Jan 2007

Low Voltage And Fast Speed All-Polymeric Optocouplers, Yan Yao, Hsiang-Yu Chen, Jinsong Huang, Yang Yang

Mechanical & Materials Engineering Faculty Publications

An all-polymeric optocoupler has been demonstrated with a polymer light-emitting diode (PLED) as the light source (input unit) and a polymer/fullerene photodiode (PD) as the detector (output unit). The electroluminescence (EL) peak of the PLED is 560 nm, and the entire EL spectrum is within the response range of the PD. The optocoupler can work at low driving voltages, 5 V on the PLED and 0 V on the PD. The output photocurrent increases linearly with input current, and the current density transfer ratio reaches 1.5%. The frequency response of the optocoupler is at 500 kHz. With comparable ...