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Articles 1 - 30 of 31
Full-Text Articles in Nanoscience and Nanotechnology
Experimentally Validated 3d Md Model For Afm-Based Tip-Based Nanomanufacturing, Rapeepan Promyoo
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
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
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
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
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
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 …
Interactive Physics And Characteristics Of Photons And Photoelectrons In Hyperbranched Zinc Oxide Nanostructures, Garrett Edward Torix
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 …
Coarse-Grained Simulations Of The Self-Assembly Of Dna-Linked Gold Nanoparticle Building Blocks, Charles Wrightsman Armistead
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 …
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 …
Synthesis, Characterization, And Fabrication Of All Inorganic Quantum Dot Leds, Haider Baqer Salman
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 …
Potential Applications For Halloysite Nanotubes Based Drug Delivery Systems, Lin Sun
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 …
Lab-On-A-Chip Nucleic-Acid Analysis Towards Point-Of-Care Applications, Varun Lingaiah Kopparthy
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 …
Generalized Partial Directed Coherence And Centrality Measures In Brain Networks For Epileptogenic Focus Localization, Joshua Aaron Adkinson
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 …
Nanophotonics For Dark Materials, Filters, And Optical Magnetism, Mengren Man
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
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
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
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
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
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
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
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.
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 …
Ultra-Thin Boron Nitride Films By Pulsed Laser Deposition: Plasma Diagnostics, Synthesis, And Device Transport, Nicholas Robert Glavin
Ultra-Thin Boron Nitride Films By Pulsed Laser Deposition: Plasma Diagnostics, Synthesis, And Device Transport, Nicholas Robert Glavin
Open Access Dissertations
This work describes, for the first time, a pulsed laser deposition (PLD) technique for growth of large area, stoichiometric ultra-thin hexagonal and amorphous boron nitride for next generation 2D material electronics. The growth of boron nitride, in this case, is driven by the high kinetic energies and chemical reactivities of the condensing species formed from physical vapor deposition (PVD) processes, which can facilitate growth over large areas and at reduced substrate temperatures. The use of optical emission spectroscopy during plasma growth provides insight into chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated …
Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn
Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn
Open Access Theses
Molecular dynamics (MD) simulations provide a useful and simple means of calculating the nanoscale thermal properties of materials, which requires special analysis since the thermal properties of materials change when their dimensions reach the nanoscale. In this research, MD is used to investigate the nanoscale phonon thermal transport of materials that are attracting much interest in the areas of materials science and nuclear physics. In order to evaluate two distinct methods of calculating the thermal conductivity of materials using MD, the simulation methods are first applied to Si. Once an understanding of each simulation method is established, they are then …
Energy Harvesting Using Photovoltaic And Betavoltaic Devices, Ashish Sharma
Energy Harvesting Using Photovoltaic And Betavoltaic Devices, Ashish Sharma
Doctoral Dissertations
There is an important need for improvement in both cost and efficiency of photovoltaic cells. For improved efficiency, a better understanding of solar cell performance is required. An analytical model of thin-film silicon solar cell, which can provide an intuitive understanding of the effect of illumination on its charge carriers and electric current, is proposed. The separate cases of homogeneous and inhomogeneous charge carrier generation rates across the device are investigated. This model also provides for the study of the charge carrier transport within the quasi-neutral and depletion regions of the device, which is of an importance for thin-film solar …
Immobilization Of Cellulase For Large Scale Reactors To Reduce Cellulosic Ethanol Cost, Dezhi Zhang
Immobilization Of Cellulase For Large Scale Reactors To Reduce Cellulosic Ethanol Cost, Dezhi Zhang
Doctoral Dissertations
Cellulosic ethanol is an alternative renewable energy source. Cellulase used in the production of cellulosic ethanol is very expensive. The difficulty in separating cellulase from the cellulose solution after the hydrolysis process limits the reusability of the cellulase, which highly precludes the scales of this application because of the high cost of the enzyme. Immobilization of cellulase provides a promising approach to allow the enzyme to be recycled, thus reducing the production cost. This research focused on immobilizing cellulase for reuse to reduce the cellulosic ethanol cost.
Four immobilization techniques were explored for the immobilization of cellulase on four different …
Clay Nanotube Composites For Antibacterial Nanostructured Coatings, Christen J. Boyer
Clay Nanotube Composites For Antibacterial Nanostructured Coatings, Christen J. Boyer
Doctoral Dissertations
A surging demand for the development of new antimicrobial nanomaterials exists due to the frequency of medical device-associated infections and the transfer of pathogens from highly touched objects. Naturally occurring halloysite clay nanotubes (HNTs) have shown to be ideal particles for polymer reinforcement, time-release drug delivery, nano-reactor synthesis, and as substrate material for nanostructured coatings.
This research demonstrates the feasibility of a novel method for coating HNTs with metals for antibacterial applications. The first ever ability to coat HNTs through electrolysis was developed for customizable and multi-functional antibacterial nanoparticle platforms. HNTs were investigated as substrate for the deposition of copper …
Tunable Controlled Release Of Molecular Species From Halloysite Nanotubes, Divya Narayan Elumalai
Tunable Controlled Release Of Molecular Species From Halloysite Nanotubes, Divya Narayan Elumalai
Doctoral Dissertations
Encouraged by potential applications in rust coatings, self-healing composites, selective delivery of drugs, and catalysis, the transport of molecular species through Halloysite nanotubes (HNTs), specifically the storage and controlled release of these molecules, has attracted strong interest in recent years. HNTs are a naturally occurring biocompatible nanomaterial that are abundantly and readily available. They are alumosilicate based tubular clay nanotubes with an inner lumen of 15 nm and a length of 600-900 nm. The size of the inner lumen of HNTs may be adjusted by etching. The lumen can be loaded with functional agents like antioxidants, anticorrosion agents, flame-retardant agents, …
Tailoring Optical And Plasmon Resonances In Core-Shell And Core-Multishell Nanowires, Sarath Ramadurgam
Tailoring Optical And Plasmon Resonances In Core-Shell And Core-Multishell Nanowires, Sarath Ramadurgam
Open Access Dissertations
Semiconductor nanowires (NWs) are sub-wavelength structures which exhibit strong optical (Mie) resonances in the visible range. In addition to such optical resonances, the localized surface plasmon resonances (LSPR) in metal and semiconductor (or dielectric) based core-shell (CS) and core-multishell (CMS) NWs can be tailored to achieve novel negative-index metamaterials (NIM), extreme absorbers, invisibility cloaks and sensors. Particularly, in this dissertation, the versatility of CS and CMS NWs for the design of negative-index metamaterials in the visible range and, plasmonic light harvesting in ultrathin photocatalyst layers for water splitting are studied.
Utilizing the LSPR in the metal layer and the magnetic …
Size Specific Transfection To Mammalian Cells By Micropillar Array Electroporation, Yingbo Zu
Size Specific Transfection To Mammalian Cells By Micropillar Array Electroporation, Yingbo Zu
Doctoral Dissertations
Electroporation serves as a promising non-viral gene delivery approach, while its current configurations carry drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here, we developed a new micropillar array electroporation (MAE) platform to advance the delivery of plasmid DNA and RNA to mammalian cells. By introducing well-patterned micropillar array on the electrode surface, the number of pillars each cell faces varies with its cell membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently done and contributed to a 2.5~3 fold increase on plasmid DNA transfection and …