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Articles 1 - 22 of 22
Full-Text Articles in Engineering
An Experimental And Computational Evaluation Of The Importance Of Molecular Diffusion In Gas Gravity Currents, Jeremy Jac Herman
An Experimental And Computational Evaluation Of The Importance Of Molecular Diffusion In Gas Gravity Currents, Jeremy Jac Herman
Graduate Theses and Dissertations
The accidental release of hazardous, denser-than-air gases during their transport or manufacture is a vital area of study for process safety researchers. This project examines the importance of molecular diffusion on the developing concentration field of a gas gravity current released into a calm environment. Questions which arose from the unexpectedly severe explosion in 2005 at Buncefield, England were of particular interest. The accidental overfilling of a large tank with gasoline on a completely calm morning led to a massive open air explosion. Forensic evidence showed that at the time of ignition, a vapor cloud, most of which now appears …
Microfluidics Guided By Redox-Magnetohydrodynamics (Mhd) For Lab-On-A-Chip Applications, Vishal Sahore
Microfluidics Guided By Redox-Magnetohydrodynamics (Mhd) For Lab-On-A-Chip Applications, Vishal Sahore
Graduate Theses and Dissertations
Unique microfluidic control actuated by simply turning off and on microfabricated electrodes in a small-volume system was investigated for lab-on-a-chip applications. This was accomplished using a relatively new pumping technique of redox-magnetohydrodynamics (MHD), which as shown in this dissertation generated the important microfluidic features of flat flow profile and fluid circulation. MHD is driven by the body force, FB = j × B, which is the magnetic part of the Lorentz force equation, and its direction is given by the right hand rule. The ionic current density, j, was generated in an equimolar solution of potassium ferri/ferro cyanide by applying …
Monodentate, Bidentate And Photocrosslinkable Thiol Ligands For Improving Aqueous Biocompatible Quantum Dots, Hiroko Takeuchi
Monodentate, Bidentate And Photocrosslinkable Thiol Ligands For Improving Aqueous Biocompatible Quantum Dots, Hiroko Takeuchi
Graduate Theses and Dissertations
Water-soluble Quantum Dots (QDs) are highly sensitive fluorescent probes that are often used to study biological species. One of the most common ways to render QDs water-soluble for such applications is to apply hydrophilic thiolated ligands to the QD surface. However, these ligands are labile and can be easily exchanged on the QD surface, which can severely limit their application. As one way to overcome this limitation while maintaining a small colloidal size of QDs, we developed a method to stabilize hydrophilic thiolated ligands on the surface of QDs through the formation of a crosslinked shell using a photocrosslinking approach. …
Spectroscopic And Kinetic Study Of Copper-Exchanged Zeolites For The Selective Catalytic Reduction Of Nox With Ammonia, Shane Adam Bates
Spectroscopic And Kinetic Study Of Copper-Exchanged Zeolites For The Selective Catalytic Reduction Of Nox With Ammonia, Shane Adam Bates
Open Access Dissertations
The recent application of metal-exchanged, small-pore zeolites for use in the selective catalytic reduction (SCR) of NOx with ammonia NH3 for automotive deNOx applications has been a great stride in achieving emission standard goals. Copper-exchanged SSZ-13 (Cu-SSZ-13), the small-pore zeolite in this study, has been shown to be very hydrothermally stable and active under conditions presented in the exhaust of the lean-burn diesel engine. In this work, detailed studies were performed to identify many aspects of the active site(s) in Cu-SSZ-13 in order to learn about the standard SCR mechanism.
A series of seven Cu-SSZ-13 samples were …
Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita
Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita
Open Access Dissertations
Positive effects of ultrasound on crystallization have been known for almost 90 years. Application of ultrasound has been very successful in many industries, most notably in chemistry, creating a new branch of science - sonochemistry. However, ultrasonication has not found wide commercial application in the solidification processing. The reason for that is the complexity of underlying phenomena and the lack of predicting models which correlate processing parameters with the properties of a product. The purpose of this study is to give some contribution toward better understanding of mechanisms that lead to changes in the solidifying microstructure. It has been found …
Elucidation Of Chiral Recognition Mechanisms Of Solutes By Amylose Tris[(S)-Alpha-Methylbenzylcarbamate] Sorbent, Hung-Wei Tsui
Elucidation Of Chiral Recognition Mechanisms Of Solutes By Amylose Tris[(S)-Alpha-Methylbenzylcarbamate] Sorbent, Hung-Wei Tsui
Open Access Dissertations
Enantioselective separations of chiral molecules are important in various chemical fields, such as pharmaceuticals and agrochemicals industries. Polysaccharide-based sorbents have been widely used in chiral liquid chromatography. The recognition mechanisms which determine their enantioselectivities are not completely understood.
In this dissertation, the chiral recognition mechanisms of a widely used commercial sorbent, amylose tris[(S)-alpha-methylbenzylcarbamate], for benzoin (B) enantiomers were first studied. The HPLC data for benzoin with pure n-hexane as the mobile phase have been obtained. The behavior of sorbent-solute-hexane systems can be interpreted by considering only sorbent solute two-component interactions. Infrared (IR) spectra showed evidence of substantial hydrogen bonding (H-bonding) …
Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors, Xue Yang
Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors, Xue Yang
Open Access Dissertations
The interaction between plasma and fusion relevant materials is one of the critical issues in successfully using those materials in Tokamak reactors. This research uses molecular dynamics, kinetic Monte Carlo and binary collision approximation methods to model fusion relevant material bombarded by energetic particles to investigate retention, deposition, sputtering, erosion, blistering effects, diffusion, and so on.
The deuterium bombardment of monocrystalline tungsten was modeled by LAMMPS code using Tersoff type interatomic potential. The deuterium trapping rate, implantation depth, and stopping time in 600-2000 K tungsten bombarded by 5-100 eV deuterium atoms were simulated. Irradiated monocrystalline tungsten became amorphous prior to …
Propagation Of Sound In The Vicinity Of Rigid Porous Interfaces, Hongdan Tao
Propagation Of Sound In The Vicinity Of Rigid Porous Interfaces, Hongdan Tao
Open Access Dissertations
Propagation of sound in the vicinity of rigid porous interfaces is investigated systematically to facilitate the acoustical characterization of sound absorption materials for noise reduction applications. Various rigid porous interfaces are considered: (1) a semi-infinite porous layer; (2) a porous hard-backed surface; and (3) a porous impedance-backed layer. A closed-form solution and numerical methods are derived with respect to each rigid porous interface condition.
A modified saddle-point method is exploited to investigate the sound field emanating from a monopole source above and below a rigid porous interface. The solutions can be expressed in a form that resembles the classical Weyl-Van …
Utilizing Electron Microscopy And Spectroscopy Methods To Understand Water Structure And Water Doping, Lior Miller
Utilizing Electron Microscopy And Spectroscopy Methods To Understand Water Structure And Water Doping, Lior Miller
Open Access Dissertations
Water is the second most common element in the universe and the most studied material on earth. Most of the studies concerning water are from the fields of chemistry and biology. Hence, the structure of water molecules and short range order and interactions are well characterized and understood. However, the collective arrangement of water molecules and the long range order are still missing. Understanding of this long range order in water is needed, as it is the key to many water activities.
To fill this gap, this study utilizes a new direct method for characterization of water in the vapor …
Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng
Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng
Open Access Dissertations
By quantitating the amplitude of the unbounded stress, the continuum fracture mechanics defines the stress intensity factor K to characterize the stress and displacement fields in the vicinity of the crack tip, thereby developing the relation between the stress singularity and surface energy (energy release rate G). This G-K relation, assigning physical meaning to the stress intensity factor, makes these two fracture parameters widely used in predicting the onset of crack propagation. However, due to the discrete nature of the atomistic structures without stress singularity, there might be discrepancy between the failure prediction and the reality of nanostructured materials. Defining …
Modeling And Control Of Nanoparticle Bloodstream Concentration For Cancer Therapies, Scarlett S. Bracey
Modeling And Control Of Nanoparticle Bloodstream Concentration For Cancer Therapies, Scarlett S. Bracey
Doctoral Dissertations
Currently, the most commonly used treatments for cancerous tumors (chemotherapy, radiation, etc.) have almost no method of monitoring the administration of the treatment for adverse effects in real time. Without any real time feedback or control, treatment becomes a "guess and check" method with no way of predicting the effects of the drugs based on the actual bioavailability to the patient's body. One particular drug may be effective for one patient, yet provide no benefit to another. Doctors and scientists do not routinely attempt to quantifiably explain this discrepancy. In this work, mathematical modeling and analysis techniques are joined together …
Structural Properties Of Ferroelectric Lead (Zirconium0.5,Titanium0.5)Oxygen3 Nanotube Array And Electronic Structure Of Lao Delta-Doped Strontium Titanate, Rajendra Prasad Adhikari
Structural Properties Of Ferroelectric Lead (Zirconium0.5,Titanium0.5)Oxygen3 Nanotube Array And Electronic Structure Of Lao Delta-Doped Strontium Titanate, Rajendra Prasad Adhikari
Graduate Theses and Dissertations
In this Dissertation we begin with two introductions on: 1) ferroelectricity and related phenomena, and 2) novel properties of Oxide electronics and the generation of two dimensional electron gas. We then give theoretical background of density functional theory (including LDA+U) and pseudopotentials. The first part of research work is about structural, polarization, and dielectric properties of ferroelectric Lead Zirconate Titanate (PZT) solid solution in the form of a nanotube array, embedded in a matrix medium of different ferroelectric strengths. We use the effective Hamiltonian derived from first-principles and finite-temperature Monte Carlo methods to determine the various properties. We revealed different …
Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor
Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor
Graduate Theses and Dissertations
Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …
Multiscale Study Of Batio3 Nanostructures And Nanocomposites, Lydie Louis Louis
Multiscale Study Of Batio3 Nanostructures And Nanocomposites, Lydie Louis Louis
Graduate Theses and Dissertations
Advancements in integrated nanoelectronics will continue to require the use of unique materials or systems of materials with diverse functionalities in increasingly confined spaces.
Hence, research on finite-dimensional systems strive to unearth and expand the knowledge of fundamental physical properties in certain key materials which exhibit numerous concurrent and exploitable functions.
Correspondingly, ferroelectric nanostructures, which particularly display a plethora of complex phenomena, prevalent in countless fields of research, are noteworthy candidates. Presently, however, the assimilation of zero-(0D) and one-dimensional (1D) ferroelectric into micro- or nano-electronics has been lagging, in part due to a lack of applied and fundamental studies but …
Algae To Propellants: Biosynthesis Of 1,2-Propanediol From Algal Derived Sugars, Lauren Rachelle Merriman
Algae To Propellants: Biosynthesis Of 1,2-Propanediol From Algal Derived Sugars, Lauren Rachelle Merriman
Graduate Theses and Dissertations
Propylene glycol dinitrate (PGDN) is an important component used in the formulation of energetic materials. A renewable, environmentally-friendly and effective production technique for the production of 1,2-propanediol, an important precursor to PGDN, is desired. While fermentation of 1,2-propanediol has been achieved, it suffers from major limitations such as expensive feed sugars and relatively low yields. It is hypothesized that algae sugars could serve as a feedstock for the microbial synthesis of 1,2-propanediol, thereby reducing production costs and enhancing sustainability.
Algal biomass produced from an Algal Turf Scrubber® has proven to have significant potential as a source of fermentable materials. However, …
Creep, Fatigue And Creep-Fatigue Interactions In Modified 9% Cr - 1% Mo (P91) Steels, Valliappa Kalyanasundaram
Creep, Fatigue And Creep-Fatigue Interactions In Modified 9% Cr - 1% Mo (P91) Steels, Valliappa Kalyanasundaram
Graduate Theses and Dissertations
Grade P91 steel, from the class of advanced high-chrome ferritic steels, is one of the preferred materials for many elevated temperature structural components. Creep-fatigue (C-F) interactions, along with oxidation, can accelerate the kinetics of damage accumulation and consequently reduce such components' life. Hence, reliable C-F test data is required for meticulous consideration of C-F interactions and oxidation, which in turn is vital for sound design practices. It is also imperative to develop analytical constitutive models that can simulate and predict material response under various long-term in-service conditions using experimental data from short-term laboratory experiments. Consequently, the major objectives of the …
Improvements In Microdialysis Sampling Extraction Efficiency Using Recycled Flow, Justin Cole Deaton
Improvements In Microdialysis Sampling Extraction Efficiency Using Recycled Flow, Justin Cole Deaton
Graduate Theses and Dissertations
Incomplete recovery during microdialysis sampling is hindering important research in neurology, proteomics, and immunology. Although the current generalized solution, decreasing volumetric flow rates (Q), has been and will remain to be a useful strategy it has reached it's a physical limitation due to evaporation at the collection site. Consequently, many important signaling molecules, such as signaling proteins, remain difficult to study. It is more fundamental to consider relative recovery as a function of the interaction time between the perfusate and the environment surrounding the probe.
In this work an increase in relative recovery was predicted by a mathematical model. Using …
The Geometry And Sensitivity Of Ion-Beam Sculpted Nanopores For Single Molecule Dna Analysis, Ryan Connor Rollings
The Geometry And Sensitivity Of Ion-Beam Sculpted Nanopores For Single Molecule Dna Analysis, Ryan Connor Rollings
Graduate Theses and Dissertations
In this dissertation, the relationship between the geometry of ion-beam sculpted solid-state nanopores and their ability to analyze single DNA molecules using resistive pulse sensing is investigated. To accomplish this, the three dimensional shape of the nanopore is determined using energy filtered and tomographic transmission electron microscopy. It is shown that this information enables the prediction of the ionic current passing through a voltage biased nanopore and improves the prediction of the magnitude of current drop signals when the nanopore interacts with single DNA molecules. The dimensional stability of nanopores in solution is monitored using this information and is improved …
New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams
New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams
Graduate Theses and Dissertations
Titanate nanobelts (NBs) have structural characteristics beyond that of clays. Due to a negatively charged lattice matrix of edge-shared TiO6-octahedra, the location of intercalated cations within the interlayer space may dictate the charge-conductions. This environment may in turn govern the lattice-framework's stability and surface properties, based upon our preliminary
data.
On that basis, these nanomaterials have been found in our lab to possess superb biological compatibility that is closely related to the types of the intercalated cations. In addition, a prolonged agitation was proven to enable us to manipulate the titanate NBs' length. In a parallel study, a ripening was …
Plasmonic Nanostructures For The Absorption Enhancement Of Silicon Solar Cells, Nathan Matthias Burford
Plasmonic Nanostructures For The Absorption Enhancement Of Silicon Solar Cells, Nathan Matthias Burford
Graduate Theses and Dissertations
In this work, computational investigation of plasmonic nanostructures was conducted using the commercial finite element electromagnetics solver Ansys® HFSS. Arrays of silver toroid nanoparticles located on the surface of an amorphous silicon thin-film absorbing layer were studied for particle sizes ranging from 20 nm to 200 nm in outer diameter. Parametric optimization by calculating an approximation of the photocurrent enhancement due to the nanoparticles was performed to determine optimal surface coverage of the nanoparticles. A comparison was made between these optimized nanotoroid arrays and optimized nanosphere arrays based on spectral absorption enhancement and potential photocurrent enhancement in an amorphous silicon …
Design And Fabrication Of Nanofluidic Systems With Integrated Sensing Electrodes For Rapid Biomolecule Characterization, Taylor Bradley Busch
Design And Fabrication Of Nanofluidic Systems With Integrated Sensing Electrodes For Rapid Biomolecule Characterization, Taylor Bradley Busch
Graduate Theses and Dissertations
A transparent nanofluidic system with embedded sensing electrodes was designed and fabricated by integrating Atomic Force Microscopy (AFM) nanolithography, Focused Ion Beam (FIB) milling and metal deposition, and standard microfabrication processing. The fabrication process started with the evaporation of chrome/gold (Cr/Au) onto a Pyrex 7740 wafer followed by photolithography and wet etching of the microchannels. The wafer was patterned a second time to form Au microelectrodes with 15-45 micrometer separation gaps in the nanochannel region. Sensing electrodes (up to one micron wide) were then deposited using FIB to bridge the gaps. The nanochannels were realized through both AFM nanolithography and …
Quantum Computing With Steady State Spin Currents, Brian Matthew Sutton
Quantum Computing With Steady State Spin Currents, Brian Matthew Sutton
Open Access Theses
Many approaches to quantum computing use spatially confined qubits in the presence of dynamic fields to perform computation. These approaches are contrasted with proposals using mobile qubits in the presence of static fields. In this thesis, steady state quantum computing using mobile electrons is explored using numerical modeling. Firstly, a foundational introduction to the case of spatially confined qubits embodied via quantum dots is provided. A collection of universal gates implemented with dynamic fields is described using simulations. These gates are combined to implement a five-qubit Grover search to provide further insight on the time-dependent field approach. Secondly, the quantum …