Nanoscience and Nanotechnology Commons^™

A Molecular Dynamic Study On The Piezoelectric Properties Of Bulk Zns And Nanobelts, Rui Xie

Theses, Dissertations and Capstones

In this thesis we proved the feasibility of using classical atomic simulations, namely molecular dynamics and molecular statics, to study the piezoelectric properties of bulk and nanobelts ZnS structures, by utilizing the core-shell atomic potential model. Based on the verification of bulk and nanobelts ZnO piezoelectric constants, utilizing LAMMPS scripts and the Nyberg et al. core-shell potential, we reported the bulk ZnS piezoelectric constants calculated using three different classical interatomic core-shell ZnS potentials; the Wright and Jackson (1995) potential, the Wright and Gale (2004) potential, and the Namsani et al. (2015) potential. The simulation results showed that the Wright and …

Developments Towards High-Flux Silica Nanosphere Substrates To Support Conforming Self-Assembled Gold Nanoparticle Monolayers For Applications In Size-Selective Filtration, Ryan Baker Vincent

Theses, Dissertations and Capstones

Hydrophobic thiol coated gold nanoparticles have recently been investigated for their ability to self-assemble into robust, ultra-thin, porous membranes at a liquid-vapor interface. Due to the well-ordered, hexagonal close-packed nanoparticle arrays formed during the self-assembly process, these 2-dimensional sheets have very well-defined pore structures and have been shown to span gaps of several microns under ideal conditions. While these self-assembled nanoparticle monolayers have very promising applications in the field of size-selective filtration due to their well-defined pore structure, they need to be supported by a rigid substrate with a large amount of open area. Here, tightly packed arrays of silica …

Dlvo Approximation Methods For Predicting The Attachment Of Silver Nanoparticles To Ceramic Membranes, Anne M. Mikelonis, Sungmin Youn, Desmond F. Lawler

All Engineering Faculty Research

This article examines the influence of three common stabilizing agents (citrate, poly(vinylpyrrolidone) (PVP), and branched poly(ethylenimine) (BPEI)) on the attachment affinity of silver nanoparticles to ceramic water filters. Citrate-stabilized silver nanoparticles were found to have the highest attachment affinity (under conditions in which the surface potential was of opposite sign to the filter). This work demonstrates that the interaction between the electrical double layers plays a critical role in the attachment of nanoparticles to flat surfaces and, in particular, that predictions of double-layer interactions are sensitive to boundary condition assumptions (constant charge vs constant potential). The experimental deposition results can …

Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls", Thomas E. Wilson, Iain D. Boyd

Physics Faculty Research

The study is based on the success in obtaining the first experimental evidence for the direct excitation of coherent nanosecond-pulsed high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Acoustic phonons are detected by a superconducting bolometer, with nanosecond resolution, at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon delta-doped doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with an approximate power density of 1 kW/mm². The absorbed phonon power density in the bolometer detector is estimated to be 10 μW/mm², in …

Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, H-J. L. Gossmann

Physics Faculty Research

We report the first experimental evidence for the resonant excitation of coherent high-frequency acoustic phonons in semiconducting doping superstructures by far-infrared laser radiation. After a grating-coupled delta-doped silicon doping superlattice is illuminated with ~1 kW/mm² nanosecond-pulsed 246 GHz laser radiation, a delayed nanosecond pulse is detected by a superconducting bolometer at a time corresponding to the appropriate time-of-flight for ballistic longitudinal acoustic phonons across the (100) silicon substrate. The absorbed phonon power density in the microbolometer is observed to be ~10 μW/mm², in agreement with theory. The phonon pulse duration also matches the laser pulse duration. The …

Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Madhukar B. Kolli

Theses, Dissertations and Capstones

The exploration of biomolecular motors in nanotechnological applications has generated much interest in the scientific community. Although the recent progress has been very promising, several requirements have yet to be fulfilled in order for motor proteins to be useful in nanotechnological applications. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization …

Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson

Physics Faculty Research

We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …

Accessibility Of Home Blood Pressure Monitors For Blind And Visually Impaired People, Mark M. Uslan, Darren M. Burton, Thomas E. Wilson, Steven Taylor, Bruce S. Chertow, Jack E. Terry

Physics Faculty Research

Background: The prevalence of hypertension comorbid with diabetes is a significant health care issue. Use of the home blood pressure monitor (HBPM) for aiding in the control of hypertension is noteworthy because of benefits that accrue from following a home measurement regimen. To be usable by blind and visually impaired patients, HBPMs must have speech output to convey all screen information, an easily readable visual display, identifiable controls that are easy to use, and an accessible user manual.

Methods: Data on the physical aspects and the features and functions of nine Food and Drug Administration-approved HBPMs (eight of which were …

Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson

Physics Faculty Research

Progress is described in experiments to generate coherent terahertz acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation. Future experiments are proposed that would use the superlattice as a transducer in a terahertz cryogenic acoustic reflection microscope with sub-nanometer resolution.

Modeling The High-Speed Switching Of Far-Infrared Radiation By Photoionization In A Semiconductor, Thomas E. Wilson

Physics Faculty Research

Data from an earlier study [T. Vogel et al., Appl. Opt. 31, 329 (1992)] on the subnanosecond switching of 119-μm radiation in high-resistivity silicon by pulsed UV laser radiation, is compared with a refined one-dimensional numerical multilayer model accounting for the generation, recombination, and diffusion of the free carriers on the resulting far-infrared optical properties of the silicon. The inclusion of recent measurements for carrier-density and temperature-dependent transport parameters leads to improved agreement between experiment and theory.