Nanoscience and Nanotechnology Commons^™

Trihalomethane, Dihaloacetonitrile, And Total N-Nitrosamine Precursor Adsorption By Carbon Nanotubes: The Importance Of Surface Oxides And Pore Volume, Erin Needham

Graduate Theses and Dissertations

As drinking water sources become increasingly impaired, enhanced removal of natural organic matter (NOM) may be required to curb formation of disinfection byproducts (DBPs) upon chlor(am)ination. While carbon nanotubes (CNTs) can adsorb NOM, their properties for DBP precursor adsorption have not been elucidated. Nine types of CNTs were assessed for trihalomethane (THM), dihaloacetonitrile (DHAN), and total N-nitrosamine (TONO) precursor adsorption. Batch isotherm experiments were completed with lake water and, to simulate an impaired condition, effluent from a wastewater treatment plant (WWTP). Adsorption varied with CNT type and dose, with TONO precursors having the highest percent removals from WWTP effluent (up …

Infrared Energy Conversion In Plasmonic Fields At Two-Dimensional Semiconductors, Gregory Thomas Forcherio

Graduate Theses and Dissertations

Conversion of infrared energy within plasmonic fields at two-dimensional, semiconductive transition metal dichalcogenides (TMD) through plasmonic hot electron transport and nonlinear frequency mixing has important implications in next-generation optoelectronics. Drude-Lorentz theory and approximate discrete dipole (DDA) solutions to Maxwell’s equations guided metal nanoantenna design towards strong infrared localized surface plasmon resonance (LSPR). Excitation and damping dynamics of LSPR in heterostructures of noble metal nanoantennas and molybdenum- or tungsten-disulfide (MoS2; WS2) monolayers were examined by parallel synthesis of (i) DDA electrodynamic simulations and (ii) near-field electron energy loss (EELS) and far-field optical transmission UV-vis spectroscopic measurements. Susceptibility to second-order nonlinear frequency …

Characterization Of Coupled Gold Nanoparticles In A Sparsely Populated Square Lattice, Roy Truett French Iii

Graduate Theses and Dissertations

Metal nanoparticles deposited in regular arrays spaced at optical wavelengths support a resonance due to a coherent coupling between localized surface plasmon mode and lattice diffraction allowing for engineering of tunable devices for use in biological sensors, nanoantennae, and enhanced spectroscopy. Techniques such as electron beam lithography, focused ion beam lithography, nanosphere lithography, and nanoimprint lithography are used for fabrication but are limited by cost, device throughput, and small deposition. Polymer soft lithography and continuous dewetting of particles is a potentially viable alternative showing promise in all of those areas. This thesis developed the fabrication of a refined hydrophilic nanoimprinted …

Morphology Controlled Synthesis Of Copper Based Multimetallic Nanostructures And Their Electrocatalytic Properties For Methanol Oxidation Reaction, Leanne Elizabeth Mathurin

Graduate Theses and Dissertations

This research focuses on the development of shape-controlled synthesis of Cu NM, Cu-based bimetallic and trimetallic nanostructures, and their electrocatalytic properties for methanol oxidation reaction (MOR). Copper nanomaterials (Cu NM) with specific surface facets can tailor their catalytic activity. Understanding reagents responsible for Cu NM growth is important for morphology-controlled synthesis of the nanostructures. This research studies the halide influence on Cu NM growth and morphology in an oil-based synthesis. The morphology of the Cu NM varies with the halide type (i.e., Cl-, Br-, I-), and the halide concentration. Additionally, the type of Cu precursor also influenced the morphology of …

Molecular Dynamics Simulations Of Dna-Functionalized Nanoparticle Building Blocks On Gpus, Tyler Landon Fochtman

Graduate Theses and Dissertations

This thesis discusses massively parallel molecular dynamics simulations of nBLOCKs using graphical processing units. nBLOCKs are nanoscale building blocks composed of gold nanoparticles functionalized with single-stranded DNA molecules. To explore greater simulation time scales we implement our nBLOCK computational model as an extension to the coarse grain molecular simulator oxDNA. oxDNA is parameterized to match the thermodynamics of DNA strand hybridization as well as the mechanics of single stranded DNA and double stranded DNA. In addition to an in-depth review of our implementation details we also provide results of the model validation and performance tests. These validation and performance tests …

Development Of A Nonlinear Model For The Prediction Of Response Times Of Glucose Affinity Sensors Using Concanavalin A And Dextran And The Development Of A Differential Osmotic Glucose Affinity Sensor, Louis G. Reis

Doctoral Dissertations

With the increasing prevalence of diabetes in the United States and worldwide, blood glucose monitoring must be accurate and reliable. Current enzymatic sensors have numerous disadvantages that make them unreliable and unfavorable among patients. Recent research in glucose affinity sensors correct some of the problems that enzymatic sensors experience. Dextran and concanavalin A are two of the more common components used in glucose affinity sensors. When these sensors were first explored, a model was derived to predict the response time of a glucose affinity sensor using concanavalin A and dextran. However, the model assumed the system was linear and fell …

Synthesis, Characterization, And Activity Of Co/Fe Alumina/Silica Supported Ft Catalysts And The Study Of Promoter Effect Of Ruthenium, Sunday Azubike Esumike

Doctoral Dissertations

The alumina and hybrid alumina-silica FT catalyst were prepared by one-step solgel/oil-drop methods using metal-nitrate-solutions (method-I), and nanoparticle-metaloxides (method-2). The nanoparticle-metal-oxides did not participate in solubility equilibria in contrast to metal nitrate in method-1 causing no metal ion seepage; therefore, method-2 yields higher XRF metal loading efficiency than method-1. The thermal analysis confirmed that the metal loading by method-1 and method-2 involved two different pathways. Method-1 involves solubility equilibria in the conversion of metal-nitrate to metal- hydroxide and finally to metal-oxide, while in method-2 nanoparticle-metal-oxide remained intact during sol-gel-oil-drop and calcination steps.

The alumina supported catalysts were dominated by γ-alumina …

Plasmon-Mediated Energy Conversion In Metal Nanoparticle-Doped Hybrid Nanomaterials, Jeremy Dunklin

Graduate Theses and Dissertations

Climate change and population growth demand long-term solutions for clean water and energy. Plasmon-active nanomaterials offer a promising route towards improved energetics for efficient chemical separation and light harvesting schemes. Two material platforms featuring highly absorptive plasmonic gold nanoparticles (AuNPs) are advanced herein to maximize photon conversion into thermal or electronic energy. Optical extinction, attributable to diffraction-induced internal reflection, was enhanced up to 1.5-fold in three-dimensional polymer films containing AuNPs at interparticle separations approaching the resonant wavelength. Comprehensive methods developed to characterize heat dissipation following plasmonic absorption was extended beyond conventional optical and heat transfer descriptions, where good agreement was …

Experimentally Validated 3d Md Model For Afm-Based Tip-Based Nanomanufacturing, Rapeepan Promyoo

Open Access Dissertations

In order to control AFM-based TBN to produce precise nano-geometry efficiently, there is a need to conduct a more focused study of the effects of different parameters, such as feed, speed, and depth of cut on the process performance and outcome. This is achieved by experimentally validating a MD simulation model of nanomachining, and using it to conduct parametric studies to guide AFM-based TBN. A 3D MD model with a larger domain size was developed and used to gain a unique insight into the nanoindentation and nanoscratching processes such as the effect of tip speed (e.g. effect of tip speed …

Carbon Nanotube Thermal Interfaces And Related Applications, Stephen L. Hodson

Open Access Dissertations

The development of thermal interface materials (TIMs) is necessitated by the temperature drop across interfacing materials arising from macro and microscopic irregularities of their surfaces that constricts heat through small contact regions as well as mismatches in their thermal properties. Similar to other types of TIMs, CNT TIMs alleviate the thermal resistance across the interface by thermally bridging two materials together with cylindrical, high-aspect ratio, and nominally vertical conducting elements. Within the community of TIM engineers, the vision driving the development of CNT TIMs was born from measurements that revealed impressively high thermal conductivities of individual CNTs. This vision was …

Wave Propagation And Imaging In Structured Optical Media, Zun Huang

Open Access Dissertations

Structured optical media, usually characterized by periodic patterns of inhomogeneities in bulk materials, provide a new approach to ultimate control of wave propagation with possible practical applications: from distributed feedback lasers by diffraction gratings, to highly nonlinear performance for super-continuum generation, to fiber-optic telecommunications by microstructured photonic crystal fibers, to invisibility cloaking, to super-resolution imaging with metamaterials etc.

In particular, structured optical media allow to manipulate the wave propagation and dispersion. In this thesis, we focus on engineering the propagation phase dispersion by modulating the compositions and dimensions of the periodic elements. By tailoring the dispersion in momentum space, we …

Towards Building A Prototype Spin-Logic Device, Ashish Verma Penumatcha

Open Access Dissertations

Since the late 1980s, several key discoveries, such as Giant and Tunneling Magne- toresistance, and advances in magnetic materials have paved the way for exponentially higher bit-densities in magnetic storage. In particular, the discovery of Spin-Transfer Torque (STT) has allowed information to be written to individual magnets using spin-currents. This has replaced the more traditional Oersted-field control used in field-MRAMs and allowed further scaling of magnetic-memories. A less obvious con- sequence of STT is that it has made possible a logic-technology based on magnets controlled by spin-polarized currents. Charge-coupled Spin Logic (CSL) is one such device proposal that couples a …

Optical Sub-Diffraction Limited Focusing For Confined Heating And Lithography, Luis M. Traverso

Open Access Dissertations

Electronics and nanotechnology is constantly demanding a decrease in size of fabricated nanoscale features. This decrease in size has become much more difficult recently due to the limited resolution of optical systems that are fundamental to many nanofabrication methods. A lot of effort has been made to fabricate devices smaller than the diffraction limit of light. Creating devices that are capable of confining fields by means of interference patterns of propagating wave modes and surface plasmon, has proven successful to confine light into smaller spot sizes.

Zone plate diffraction lenses generate spots with dimensions very close to the diffraction limit. …

Liquid Metal Particle Popping: Nanoscale To Macroscale, Trevor R. Lear

Open Access Theses

Liquid metal nanoparticles can be used to produce stretchable electronic devices. Understanding the mechanical properties of liquid metal nanoparticles is crucial to optimizing their use in various applications, especially printing of flexible, stretchable electronics. Smaller nanoparticles are desired for high-resolution printing and compatibility with existing scalable manufacturing methods; however, they contain less liquid metal and are more difficult to rupture than larger particles, making them less desirable for post-processing functionality. This study investigates the mechanics of liquid metal particle rupture as a function of particle size. We employ compression of particle films to characterize the composition of the particle core …

Synthesis, Characterization, And Fabrication Of All Inorganic Quantum Dot Leds, Haider Baqer Salman

Graduate Theses and Dissertations

Quantum Dot LEDs with all inorganic materials are investigated in this thesis. The research was motivated by the potential disruptive technology of core shell quantum dots in lighting and display applications. These devices consisted of three main layers: hole transport layer (HTL), electron transport layer (ETL), and emissive layer where the emission of photons occurs. The latter part was formed of CdSe / ZnS core-shell quantum dots, which were synthesized following hot injection method. The ETL and the HTL were formed of zinc oxide nanocrystals and nickel oxide, respectively. Motivated by the low cost synthesis and deposition, NiO and ZnO …

Coarse-Grained Simulations Of The Self-Assembly Of Dna-Linked Gold Nanoparticle Building Blocks, Charles Wrightsman Armistead

Graduate Theses and Dissertations

The self-assembly of nanoparticles (NPs) of varying shape, size, and composition for the purpose of constructing useful nanoassemblies with tailored properties remains challenging. Although progress has been made to design anisotropic building blocks that exhibit the required control for the precise placement of various NPs within a defined arrangement, there still exists obstacles in the technology to maximize the programmability in the self-assembly of NP building blocks. Currently, the self-assembly of nanostructures involves much experimental trial and error. Computational modeling is a possible approach that could be utilized to facilitate the purposeful design of the self-assembly of NP building blocks …

Interactive Physics And Characteristics Of Photons And Photoelectrons In Hyperbranched Zinc Oxide Nanostructures, Garrett Edward Torix

Graduate Theses and Dissertations

As is commonly known, the world is full of technological wonders, where a multitude of electronic devices and instruments continuously help push the boundaries of scientific knowledge and discovery. These new devices and instruments of science must be utilized at peak efficiency in order to benefit humanity with the most advanced scientific knowledge. In order to attain this level of efficiency, the materials which make up these electronics, or possibly more important, the fundamental characteristics of these materials, must be fully understood. The following research attempted to uncover the properties and characteristics of a selected family of materials. Herein, zinc …

A Bifunctional Nanocomposites Based Electrochemical Biosensor For In-Field Detection Of Pathogenic Bacteria In Food, Meng Xu

Graduate Theses and Dissertations

This research focused on the application of electrochemical biosensors for the rapid detection of pathogenic bacteria, Escherichia coli O157:H7 and Salmonella Typhimurium, in foods. The possible presence of pathogenic bacteria in foods has always been a great threat to the wellbeing of people and the revenue of food companies. Therefore, the demand for rapid and sensitive methods to detect foodborne pathogens is growing. In this research, an impedimetric immunosensor was first developed for the rapid detection of E. coli O157:H7 and S. Typhimurium in foods. It was based on the techniques of immunomagnetic separation, enzyme labelling, and electrochemical impedance spectroscopy …

Potential Applications For Halloysite Nanotubes Based Drug Delivery Systems, Lin Sun

Doctoral Dissertations

Drug delivery refers to approaches, formulations, technologies, and systems for transporting a drug in the body. The purpose is to enhance the drug efficacy and to reduce side reactions, which can significantly improve treatment outcomes. Halloysite is a naturally occurred alumino-silicate clay with a tubular structure. It is a biocompatible material with a big surface area which can be used for attachment of targeted molecules. Besides, loaded molecules can present a sustained release manner in solution. These properties make halloysite nanotubes (HNTs) a good option for drug delivery.

In this study, a drug delivery system was built based on halloysite …

Generalized Partial Directed Coherence And Centrality Measures In Brain Networks For Epileptogenic Focus Localization, Joshua Aaron Adkinson

Doctoral Dissertations

Accurate epileptogenic focus localization is required prior to surgical resection of brain tissue for treatment of patients with intractable temporal lobe epilepsy, a clinical need that is partially fulfilled to date through a subjective, and at times inconclusive, evaluation of the recorded electroencephalogram (EEG). Using brain connectivity analysis, patterns of causal interactions between brain regions were derived from multichannel EEG of 127 seizures in nine patients with focal, temporal lobe epilepsy (TLE). The statistically significant directed interactions in the reconstructed brain networks were estimated from three second intracranial multi-electrode EEG segments using the Generalized Partial Directed Coherence (GPDC) and validated …

Lab-On-A-Chip Nucleic-Acid Analysis Towards Point-Of-Care Applications, Varun Lingaiah Kopparthy

Doctoral Dissertations

Recent infectious disease outbreaks, such as Ebola in 2013, highlight the need for fast and accurate diagnostic tools to combat the global spread of the disease. Detection and identification of the disease-causing viruses and bacteria at the genetic level is required for accurate diagnosis of the disease. Nucleic acid analysis systems have shown promise in identifying diseases such as HIV, anthrax, and Ebola in the past. Conventional nucleic acid analysis systems are still time consuming, and are not suitable for point-ofcare applications. Miniaturized nucleic acid systems has shown great promise for rapid analysis, but they have not been commercialized due …

Nanophotonics For Dark Materials, Filters, And Optical Magnetism, Mengren Man

Open Access Dissertations

Research on nanophotonic structures for three application areas is described, a near perfect optical absorber based on a graphene/dielectric stack, an ultraviolet bandpass filter formed with an aluminum/dielectric stack, and structures exhibiting homogenizable magnetic properties at infrared frequencies. The graphene stack can be treated as a effective, homogenized medium that can be designed to reflect little light and absorb an astoundingly high amount per unit thickness, making it an ideal dark material and providing a new avenue for photonic devices based on two-dimensional materials. Another material stack arrangement with thin layers of metal and insulator forms a multi-cavity filter that …

Efficient Inelastic Scattering In Atomistic Tight Binding, James A. Charles

Open Access Theses

In this thesis, the coherent and incoherent transport simulation capabilities of the multipurpose nanodevice simulation tool NEMO5 are presented and applied on transport in tunneling field-effect transistors (TFET). A gentle introduction is given to the non-equilibrium Green's function theory. The comparison with experimental resistivity data confirms the validity of the electron-phonon scattering models. Common pitfalls of numerical implementations such as current conservation, energy mesh resolution, and recursive Green's function stability and the applicability of common approximations of scattering self-energies are discussed. The impact of phonon-assisted tunneling on the performance of TFETs is exemplified with a concrete Si nanowire device. The …

Laser Direct Written Silicon Nanowires For Electronic And Sensing Applications, Woongsik Nam

Open Access Dissertations

Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, …

Physical Properties, Evaporation And Combustion Characteristics Of Nanofluid-Type Fuels, Saad Tanvir

Open Access Dissertations

Nanofluids are liquids with stable suspension of nanoparticles. Limited studies in the past have shown that both energetic and catalytic nanoparticles once mixed with traditional liquid fuels can be advantageous in combustion applications, e.g., increased energy density and shortened ignition delay. Contradictions in existing literature, scarcity of experimental data and lack of understanding on how the added nanoparticles affect the physical properties as well as combustion characteristics of the resulting fuel motivated us to launch a detailed experimental and theoretical investigation.

The surface tension of ethanol and n-decane based nanofluid fuels containing suspended nanoparticles were measured using the pendant drop …

Photoluminescence Measurement On Low-Temperature Metal Modulation Epitaxy Grown Gan, Yang Wu

Graduate Theses and Dissertations

A low-temperature photoluminescence (PL) study was conducted on low-temperature metal modulation epitaxy (MME) grown GaN. By comparing the PL signal from high temperature grown GaN buffer layers, and MME grown cap layers on top of the buffer layers, it was found that MME grown GaN cap has a significantly greater defect-related emission. The band edge PL from MME grown GaN found to be 3.51eV at low temperature. The binding energy of the exciton in GaN is determined to be 21meV through temperature dependence analysis. A PL peak at 3.29eV was found in the luminescence of the MME grown cap layer, …

Study Of Plasmonic Properties Of The Gold Nanorods In The Visible To Near Infrared Light Regime, Pijush Kanti Ghosh

Graduate Theses and Dissertations

Nanostructures of noble metals show unique plasmonic behavior in the visible to near-infrared light range. Gold nanostructures exhibit a particularly strong plasmonic response for these wavelengths of light. In this study we have investigated optical enhancement and absorption of gold nanorods with different thickness using finite element method simulations. This study reports on the resonance wavelength of the sharp-corner and round-corner rectangles of constant length 100 nm and width 60 nm. The result shows that resonance wavelength depends on the polarization of the incident light; there also exists a strong dependence of the optical enhancement and absorption on the thickness …

Studies On The Electrical Transport Properties Of Carbon Nanotube Composites, Taylor Warren Tarlton

Doctoral Dissertations

This work presents a probabilistic approach to model the electrical transport properties of carbon nanotube composite materials. A pseudo-random generation method is presented with the ability to generate 3-D samples with a variety of different configurations. Periodic boundary conditions are employed in the directions perpendicular to transport to minimize edge effects. Simulations produce values for drift velocity, carrier mobility, and conductivity in samples that account for geometrical features resembling those found in the lab. All results show an excellent agreement to the well-known power law characteristic of percolation processes, which is used to compare across simulations. The effect of sample …

Nano Clay-Enhanced Calcium Phosphate Cements And Hydrogels For Biomedical Applications, Udayabhanu Jammalamadaka

Doctoral Dissertations

Biomaterials are used as templates for drug delivery, scaffolds in tissue engineering, grafts in surgeries, and support for tissue regeneration. Novel biomaterial composites are needed to meet multifaceted requirements of compatibility, ease of fabrication and controlled drug delivery. Currently used biomaterials in orthopedics surgeries suffer limitations in toxicity and preventing infections. Polymethyl methacrylate (PMMA) used as bone cement suffers from limitations of thermal necrosis and monomer toxicity calls for development of better cementing biomaterials. A biodegradable/bioresorbable cement with good mechanical properties is needed to address this short coming. Metal implants used in fixing fractures or total joint replacement needs improvements …

Phase-Field Models For Simulating Physical Vapor Deposition And Microstructure Evolution Of Thin Films, James Stewart Jr.

Graduate Theses and Dissertations

The focus of this research is to develop, implement, and utilize phase-field models to study microstructure evolution in thin films during physical vapor deposition (PVD). There are four main goals to this dissertation. First, a phase-field model is developed to simulate PVD of a single-phase polycrystalline material by coupling previous modeling efforts on deposition of single-phase materials and grain evolution in polycrystalline materials. Second, a phase-field model is developed to simulate PVD of a polymorphic material by coupling previous modeling efforts on PVD of a single-phase material, evolution in multiphase materials, and phase nucleation. Third, a novel free energy functional …