Nanoscience and Nanotechnology Commons^™

Patterning And Mechanical Analysis Of Fiber-Based Materials, Samuel A. Pendergraph

Doctoral Dissertations

The ability to define and control the topography of a surface has been studied extensively due to its importance in a wide variety of applications. The control of a non-planar topography would be very valuable since a number of structures that are pervasive in artificial applications (e.g. fibers, lenses) are curved interfaces. This potential of enabling applications that incorporate non-planar geometries was the motivation for this thesis. The first study of this thesis comprises the study of patterning the circumference of micrometer sized fibers. Specifically, a unique technique was described to pattern the fiber with a periodic array of colloids. …

Structural, Electronic And Catalytic Properties Of Graphene-Supported Platinum Nanoclusters, Ioanna Fampiou

Doctoral Dissertations

Carbon materials are predominantly used as catalytic supports due to their high surface area, excellent electrical conductivity, resistance to corrosion and structural stability. Graphene, a 2D monolayer of graphite, with its excellent thermal, electronic and mechanical features, has been considered a promising support material for next generation metal-graphene nanocatalysts. The main focus of this dissertation is to investigate the properties of such metal-graphene nanocomposites using computational methods, and to develop a comprehensive understanding of the experimentally observed enhanced catalytic activity of graphene-supported Platinum (Pt) clusters. In particular, we seek to understand the role of graphene supports on the ground-state morphology …

Quartz-Mems: Wet Chemical Etching Assisted By Electromagnetic Energy Sources For The Development Of Quartz Crystal To Be Used For Microelectromechanical Systems, William J. Clower

Doctoral Dissertations

Quartz crystal resonators have been the most commonly used timing devices to date. Today's timing market requires devices to be as small as possible and consume smaller amounts of energy. Because of the market demand, many startup companies have formed to develop silicon resonators as timing devices. Silicon resonators have poor noise and temperature performance (due to its linear temperature versus frequency coefficient). At the moment the only advantage that silicon resonators have over quartz crystal resonators is a small form factor. The photolithography processing method currently being used in industry is a very tedious task, requiring multiple etching steps …

Applications Of Halloysite Nanocontainers For Functional Protective Coating, Anupam Ramesh Joshi

Doctoral Dissertations

In this study we have explored the applications of halloysite clay nanotubes as a nanocontainer. Halloysite nanotubes are used as a storage unit for anticorrosion agents, flame retardants, and a dopant to extend the curing time for geopolymer composites. Halloysite is a naturally occurring clay mineral with a chemical formula of Al2Si2O 5(OH)4 · 2 H2O and is identical to kaolinite with the exception that it holds an additional water monolayer in its interlayered spaces. Upon heating at higher temperatures, halloysite loses the additional water monolayer, and this variant known colloquially as "meta-halloysite" has a chemical formula of Al2Si2O5(OH) 4 …

Computational Study Of Sodium Magnesium Hydride For Hydrogen Storage Applications, Fernando Antonio Soto Valle

Doctoral Dissertations

Hydrogen offers considerable potential benefits as an energy carrier. However, safe and convenient storage of hydrogen is one of the biggest challenges to be resolved in the near future. Sodium magnesium hydride (NaMgH 3) has attracted attention as a hydrogen storage material due to its light weight and high volumetric hydrogen density of 88 kg/m3. Despite the advantages, hydrogen release in this material occurs at approximately 670 K, which is well above the operable range for on-board hydrogen storage applications. In this regard, hydrogen release may be facilitated by substitution doping of transition-metals. This dissertation describes first-principles computational methods that …

Nanotechnology And Additive Manufacturing Platforms For Clinical Medicine: An Investigation Of 3d Printing Bioactive Constructs And Halloysite Nanotubes For Drug Delivery And Biomaterials, Jeffery A. Weisman

Doctoral Dissertations

Personalized medicine requires the development of new technologies for controlled or targeted drug delivery. Three-dimensional (3D) printing and additive manufacturing techniques can be used to generate customized constructs for bioactive compound delivery. Nanotechnology in the form of nanoparticles, used as a stand-alone construct or for material enhancements, can significantly improve established biomaterials such as PMMA based bone cements or enable new technology to have enhanced capabilities. Combinations of the technologies can be used in such applications as infectious disease treatments, chemotherapeutic targeted drug delivery or targeted delivery of nearly any bioactive compound.

Chemotherapeutic or antibiotic enhanced 3D printing filaments were …

Quantum Tuning Of Plasmons In Ultrathin Metal Films, Ao Teng

Doctoral Dissertations

The surface plasmon is a coherent charge density oscillation localized at a metal surface. It can couple with light and the resulting plasmon-polariton hybrid mode is confined to volumes that are much smaller than the classical diffraction limit of light. Nano-plasmonics is a rapidly evolving field where light manipulation at the nanoscale may lead to novel applications. However, as the size of plasmonic devices approaches the quantum-size regime, the macroscopic picture of plasmon may no longer be valid. To elucidate the influence of the discretization of the single particle spectrum on the collective plasmon response, we performed a systematic study …

Thermoelectric Elisa For Quantification Of 8ohdg In A Microfluidic Device, Gergana Nestorova

Doctoral Dissertations

This research demonstrates the feasibility of a novel method for performing thermoelectric enzyme-linked immunosorbent assay (ELISA) in a microfluidic device. The feasibility of the thermoelectric ELISA is demonstrated by measuring the concentration of 8-hydroxy 2-deoxyguanosine (8OHdG) in urine samples from amyloid precursor protein (APP) transgenic mice. The detection method is based on formation of a complex between 8OHdG and anti-8OHdG capture antibody conjugated to biotin. The complex is immobilized over the measuring junctions of a thermopile via biotin streptavidin interaction. The concentration of the analyte is determined by using enzyme linked secondary IgG antibody specific to the primary one. The …

Micro And Nano Technology Platforms: From Cell Viability Monitoring To Fet Based Biosensing, Pushparaj D. Pathak

Doctoral Dissertations

Nanotechnology is a multidisciplinary field that combines science and engineering to design, synthesize, characterize and explore applications for materials and devices whose smallest functional organization in at least one dimension is on the nanometer scale. Nanotechnology is undergoing an explosive development and the extent of potential application is vast and widely diverse. In the field of human health care, nanotechnology is helping to develop novel materials and structures, which have made it possible to miniaturize many of the tools used in conventional assays. Smart biochips constructed out of these novel materials and structures are now capable of performing limited in …

Nanostructured Aluminum Oxide (Nao): Enhanced Fluorescence Imaging And Sensing, Xiang Li

Doctoral Dissertations

A new fluorescence enhancement technical platform based on nanostructured aluminum oxide (NAO) has been discovered. Experiments reveal that this new platform can enhance the fluorescence signals up to two or three orders of magnitude compared to a traditional glass substrate platform. In order to realize a large-scale arrayed fluorescence biosensing platform for high throughput applications, a rapid and cost-effective process has been developed to fabricate the micropatterned NAO of a variety of shapes. An optical characterization technology, by introducing UV light irradiance, has been found for the first time to determine if the NAO has been formed from Al and …

Hybrid Nanomaterial And Its Applications: Ir Sensing And Energy Harvesting, Yi-Hsuan Tseng

Doctoral Dissertations

In this dissertation, a hybrid nanomaterial, single-wall carbon nanotubes-copper sulfide nanoparticles (SWNTs-CuS NPs), was synthesized and its properties were analyzed. Due to its unique optical and thermal properties, the hybrid nanomaterial exhibited great potential for infrared (IR) sensing and energy harvesting.

The hybrid nanomaterial was synthesized with the non-covalent bond technique to functionalize the surface of the SWNTs and bind the CuS nanoparticles on the surface of the SWNTs. For testing and analyzing the hybrid nanomaterial, SWNTs-CuS nanoparticles were formed as a thin film structure using the vacuum filtration method. Two conductive wires were bound on the ends of the …

Study And Development Of Sulfated Zirconia Based Proton Exchange Fuel Cell Membranes, Brittany Wilson Kemp

Doctoral Dissertations

With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with Nafion®, the main membrane for PEMFCs, has not been solved. Nafion® restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to Nafion® in PEMFCs.

The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. …

Selected Durability Studies Of Geopolymer Concrete With Respect To Carbonation, Elevated Temperature, And Microbial Induced Corrosion, Mohammad Sufian Badar

Doctoral Dissertations

This thesis reports a comprehensive study related to the experimental evaluation of carbonation in reinforced geopolymer concrete, the evaluation of geopolymer concretes at elevated temperature, and the resistance of geopolymer concrete to microbial induced corrosion (MIC).

Carbonation: Reinforced concretes, made of geopolymer, prepared from two class F fly ashes and one class C fly ash, were subjected to accelerated carbonation treatment for a period of 450 days. Electrochemical, microstructure and pore structure examinations were performed to evaluate the effect of corrosion caused due to carbonation. GPC specimens prepared from class F fly ash exhibited lower corrosion rates by a factor …

Development Of A Nitrogen Incorporated Ultrananocrystalline Diamond Film Based Field Emitter Array For A Flat Panel X-Ray Source, Chrystian Mauricio Posada

Doctoral Dissertations

"As an alternative to conventional X-ray sources, a flat panel transmission X-ray source is being developed. A field emitter array (FEA) prototype to be incorporated as cold cathode in this flat panel X-ray source was fabricated for this work. Using the Particle-in-Cell code OOPIC Pro, an initial FEA was designed through simulations. Based on the simulation results, a FEA prototype was fabricated using conventional microfabrication techniques. Planar nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) films were used as field emitters. This N-UNCD based FEA prototype was composed of 9 pixels distributed in a 3x3 array, with a pixel size of 225x225 µm, and …

Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera

Doctoral Dissertations

In this work, a systematic computational study directed toward developing a molecular-level understanding of gas adsorption and diffusion characteristics in nano-porous materials is presented. Two different types of porous adsorbents were studied, one crystalline and the other amorphous. Physisorption and diffusion of hydrogen in ten iso-reticular metal-organic frameworks (IRMOFs) were investigated. A set of nine adsorbents taken from a class of novel, amorphous nano-porous materials composed of spherosilicate building blocks and isolated metal sites was also studied, with attention paid to the adsorptive and diffusive behavior of hydrogen, methane, carbon dioxide and their binary mixtures. Both classes of materials were …

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the adhesion force strengthens …

Micro Solar Thermal Energy Development And Use For Mems Power Applications, Emmanuel Ogbonnaya

Doctoral Dissertations

Increasing focus on alternative energy sources has produced significant progress across a wide variety of research areas. One particular area of interest has been solar energy. The sun represents sustainable and renewable energy source capable of meeting present energy needs without compromising the ability of future generations to meet theirs. Energy from the sun can be utilized in multiple ways. Direct rise in modern power generation typically involves either photovoltaic systems or large-scale solar thermal energy installations. While large-scale solar thermal energy generation is well advanced, there has been comparatively little research on smaller scale thermal energy collection and application. …

Plasmonics Resonance Enhanced Active Photothermal Effects In Aluminum Nanoenergetics For Propulsion Applications, Jacques Abboud

Doctoral Dissertations

In this dissertation, aluminum nanoparticles (Al NPs) are shown capable to on-demand enhance and control the local photothermal energy deposition, both spatially and temporally, via active photothermal effects initiated by the localized surface plasmon resonance (LSPR) phenomenon, and amplified by the Al exothermal oxidation reactions. Experiments in dry and wet environments along with computational modeling of the photothermal process are very desirable for gaining fundamental understanding, ignition optimization and parameter exploration.

Combined phenomena of motion and ignition of Al NPs are explored first in this study. Both resulting from exposing a pile of the nanoenergetics in hand to a single …

Novel Bimetallic Plasmonic Nanomaterials, Ritesh Sachan

Doctoral Dissertations

Plasmonic nanomaterials have attracted a lot of attention recently due to their application in various fields such as chemical and biological sensing, catalysis, energy harvesting and optical devices. However, there is a need to address several outstanding issues with these materials, including cost-effective synthesis, tunability in plasmonic characteristics, and long term stability. In this thesis, we have focused on bimetallic nanoparticles (NPs) of Ag and Co due to their immiscibility as well as their individual properties. First, a pulsed laser induced dewetting route was used to synthesize Ag-Co bimetallic plasmonic NPs. An synthesis parameter space was derived to show the …

Femtosecond Laser Patterned Templates And Imprinted Polymer Structures, Deepak Rajput

Doctoral Dissertations

Femtosecond laser machining is a direct-write lithography technique by which user-defined patterns are efficiently and rapidly generated at the surface or within the bulk of transparent materials. When femtosecond laser machining is performed with tightly focused amplified pulses in single-pulse mode, transparent substrates like fused silica can be surface patterned with high aspect ratio (>10:1) and deep (>10 μm) nanoholes. The main objective behind this dissertation is to develop single-pulse amplified femtosecond laser machining into a novel technique for the production of fused silica templates with user-defined patterns made of high aspect ratio nanoholes. The size of the …

The Effect Of Network Transitions On Spontaneous Activity And Sycnhrony In Devloping Neural Networks, Jude P. J. Savarraj

Doctoral Dissertations

Connectivity patterns of developing neural circuits and the effects of its dynamics on network behavior, particularly the emergence of spontaneous activity and synchrony, are not clear. We attempt to quantify anatomical connectivity patterns of rat cortical cultures during different stages of development. By culturing the networks on dishes embedded with micro electrode arrays, we simultaneously record electrical activity from multiple regions of the developing network and monitor its electrical behavior, particularly its tendency to fire spontaneously and to synchronize under certain conditions. We investigate possible correlations between changes in the network connectivity patterns and spontaneous electrical activity and synchrony. Cocultures …

Intrinsic Mode Function Synchronization Measures For The Anticipation Of Seizures In Epilpsy, Daniel William Moller

Doctoral Dissertations

Epileptic seizures affect as many as 50 million people and often occur without warning or apparent provocation. We explore the applicability of noise-assisted Ensemble Empirical Mode Decomposition (EEMD) for patient-specific seizure anticipation synchronization measures as applied to the EEMD intrinsic mode function (IMF) output. Intracranial EEG data were obtained from pre-surgical monitoring at the Epilepsy Center of the University Hospital of Freiburg. Data from twenty patients were analyzed. For each recorded channel, non-overlapping time windows were submitted to the EEMD algorithm, producing twelve levels of IMFs. IMF synchronization measures (mean and maximum coherence, mean and maximum cross-correlation, correlation coefficient and …

Ultrasonication Assisted Layer-By-Layer Technology For The Preparation Of Multi-Functional Anticancer Drugs Paclitaxel And Lapatinib, Xingcai Zhang

Doctoral Dissertations

In this dissertation, ultrasonication assisted Layer-by-Layer (LbL) technology for the preparation of multifunctional poorly water-soluble anticancer drug nanoparticles, paclitaxel and lapatinib, has been developed. Many FDA approved drugs are very low soluble in water; therefore, it is very difficult to load and control their release and targeting efficiently, which greatly confines their application. The development of this method will pave the way for the development and application of those low soluble anticancer drugs.

In the first part of this dissertation, the first approach for powerful ultrasonication, the top-down approach (sonicating bulk drug crystals in polyelectrolyte solution), was successfully applied for …

Multi-Scale Characterization Of Nanostructured Sodium Aluminum Hydride, Shathabish Narasegowda

Doctoral Dissertations

Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to …

Oscillator-Based Neuronal Modeling For Seizure Progression Investigation And Seizure Control Strategy, Wu Chen

Doctoral Dissertations

The coupled oscillator model has previously been used for the simulation of neuronal activities in in vitro rat hippocampal slice seizure data and the evaluation of seizure suppression algorithms. Each model unit can be described as either an oscillator which can generate action potential spike trains without inputs, or a threshold-based unit. With the change of only one parameter, each unit can either be an oscillator or a threshold-based spiking unit. This would eliminate the need for a new set of equations for each type of unit. Previous analysis has suggested that long kernel duration and imbalance of inhibitory feedback …

Exploitation And Exploration Of Pcr In Microfluidic Systems With Gradient Temperature Environments, Ilija Pjescic

Doctoral Dissertations

The main goal of the work was to establish a wholesome picture off all relevant processes for a sample-in, answer out genetic system and to integrate the whole process on a one step device from sample collection to final result. The genetic analysis process consists of ideally three steps: sample preparation, chemical reaction, and analysis. Each of the steps is different and requires a specific environment, where sample preparation might use additives, they might later interfere with the reaction itself or lead to misleading results in the analysis phase. It was found to be quite a challenging process to synchronize …

A Nanostructured Fabry-Perot Interferometer For Label-Free Biodetection, Tianhua Zhang

Doctoral Dissertations

A polymer nanostructured Fabry-Perot interferometer (FPI) based biosensor has been developed, fabricated, and tested. Different from a conventional FPI, this nanostructured FPI has a layer of Au-coated nanopores inside its cavity. The Au-coated nanostructure layer offers significant enhancement of optical transducing signals due to the localized surface Plasmon resonance (L-SPR) effect. Compared to a traditional FPI for label-free biosensing applications, the polymer nanostructured FPI based biosensor offers increased sensing surface area, extended penetration depth of the excitation light, and amplification of optical transducing signals. Using a nanostructured FPI, measurements taken had great improvements in free spectral range (FSR), finesse, and …

Nanowire Giant Magnetoresistance Thin Films For Magnetic Sensors, Bryan Cox

Doctoral Dissertations

This dissertation details a novel method to fabricate magnetic sensors using nanowire giant magnetoresistance (GMR) thin films. In 1988, Albert Fert and Peter Grünberg both independently discovered a new physical phenomenon called GMR. GMR is a quantum mechanical effect found in thin film materials that are composed of alternating nanoscale ferromagnetic and non-magnetic conductive layers. When a GMR material is in the presence of a magnetic field, a change in electrical resistance is observed. The GMR effect has been utilized to produce magnetic sensors that have been used in a variety of applications, such as computer hard drive read heads, …

Towards Sustainable Development Of Nanomanufacturing, Sasikumar Ramdas Naidu

Doctoral Dissertations

"Sustainability" is a buzz word these days not just among regulatory agencies but even with corporations, as evident by the release of annual sustainability report by a large number of firms. Companies are starting to portray profit making along with corporate environmental responsibility.

Nanotechnology and nanomanufacturing which holds a lot of promise for development in a multitude of fields in science and engineering is the new kid on the block and carries a lot of apprehension due to public concern about their potential unwanted side effects that may result in the case of an untoward incident or lack of oversight. …

Fabrication And Characterization Of Hybrid Energy Harvesting Microdevices, Zhongcheng Gong

Doctoral Dissertations

In this dissertation, a hybrid energy harvesting system based on a lead zirconate titanate (PZT) and carbon nanotube film (CNF) cantilever structure has been designed, fabricated and studied. It has the ability to harvest light and thermal radiation energy from ambient energy and convert them to electricity.

The proposed micro-scale energy harvesting device consists of a composite cantilever beam (SU-8/CNF/Pt/PZT/Pt) which is fixed on a silicon based anchor and two electrode pads for wire bonding. The CNF acts as an antenna to receive radiation energy and convert it to heat energy and then transfer to the whole cantilever structure. The …