Nanoscience and Nanotechnology Commons^™

Polymer-Enhanced Nanopore Sensing, Eugene Gyasi Agyemang

Graduate Theses and Dissertations

The resistive pulse technique characterizes single analytes by detecting fluctuations in the ion current as they pass through a narrow orifice connecting two electrolyte-filled chambers, each containing a single electrode. The amplitude, shape, frequency, and duration of these fluctuations primarily provide information about the analyte’s size, shape, concentration, and net surface charge, respectively. One configuration for resistive pulse measurements is of an electrolyte-filled nanopipette immersed in a bath, where the nanopipette tip acts as the nanoscale orifice. It was previously shown that incorporating the large quantities polymer polyethylene glycol (PEG 8K, 50% w/v) into the external electrolyte bath dramatically enhanced …

Growth And Characterization Of Thin Film Gase On Si(111) And Sio2/Si(001) Substrates By Molecular Beam Epitaxy, Christopher John Hocevar

Graduate Theses and Dissertations

Gallium selenide (GaSe) is a thin-film semiconducting material with promising optoelectronic properties, including a tunable bandgap, high photosensitivity, and atomic-layer scalability. These characteristics make it suitable for devices such as photodiodes, FETs, MOSFETs, Hall effect sensors, and p–n diodes. In this study, GaSe thin films were grown on SiO2 and Si(111)-7×7 substrates using molecular beam epitaxy (MBE) to compare growth behavior across different substrates. The films were characterized using Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectroscopy, and reflection high-energy electron diffraction (RHEED). RHEED confirmed the 7×7 reconstruction of the Si(111) surface and the amorphous nature …

Investigating Functionalized Cvd Graphene Heterostructures As Platforms For Hydrogen Gas Sensing, Evans Asiedu Addo-Mensah

Graduate Theses and Dissertations

The hydrogen economy is rapidly advancing and is poised to become one of the world's largest economies, driven by the abundance of hydrogen gas. Several organizations, particularly in the United States of America, are closely or have been monitoring this development, with rapidly increasing interest. Considering that hydrogen gas has no taste, smell (odor), or color, and very combustible, it’s imperative to develop detectors and sensors capable of rapidly detecting leaks to prevent application disasters. Owing to its extraordinary mechanical and electrical characteristics, graphene is the material that has been studied the most. When combined with hexagonal boron nitride (hBN), …

In-Situ Tribology Of Engineered Surfaces With 3d-Printed Micro/Nano-Textures, Mahyar Afshar Mohajer

Graduate Theses and Dissertations

Surface texturing is an effective way to reduce the adhesion and friction between two contacting surfaces by reducing the real area of contact between them, providing a potential solution for adhesion and friction-induced failures, for example, failures in micro-/nano-electromechanical systems (MEMS/NEMS). Surface texturing is also essential to the realization of functional surfaces such as superhydrophobic/philic and icephobic surfaces. However, textures are prone to deformation due to being subjected to higher contact pressures. The advancement of 3D nanoprinting by two-photon lithography (TPL), combined with the ability to make an in-situ observation of the interplay between the forces and the sliding surfaces …

Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi

Graduate Theses and Dissertations

This work focuses on the investigation of gate-defined quantum dots in two-dimensional transition metal dichalcogenide tungsten diselenide (WSe2) as a means to unravel mesoscopic physical phenomena such as valley-contrasting physics in WSe2 flakes and its potential application as qubit, as well as realizing gate-controlled quantum dots based on elementaltellurium nanostructures which may unlock the topological nature of the host material carriers such as Weyl states in tellurium nanowires.The fabrication and characterization of gate-defined hole quantum dots in monolayer and bilayer WSe2 are reported. The gate electrodes in the device design are located above and below the WSe2 nanoflakes to accumulate …

Photoassisted Nanoscale Memory Resistors, Amir Shariffar

Graduate Theses and Dissertations

Memristors or memory resistors are promising two-terminal devices, which have the potential to revolutionize current electronic memory technologies. Memristors have been extensively investigated and reported to be practical devices, although they still suffer from poor stability, low retention time, and laborious fabrication processes.

The primary aim of this project was to achieve a device structure of quantum dots or thin films to address a fundamental challenge of unstable resistive switching behavior in memristors. Moreover, we aimed to investigate the effects of light illumination in terms of intensity and wavelength on the performance of the fabricated memristor. The parameters such as …

Thermometry Via Diffusion In Ferrous Core-Shell Nanoparticles For Induction Heating Applications, Hayden Carlton

Graduate Theses and Dissertations

Induction heating causes the release of enormous amounts of heat from dispersed magnetic nanoparticles. While the rate of heat transfer can be easily quantified calorimetrically, measuring the temperature of the nanoparticles on the nanoscale presents experimental challenges. Fully characterizing the temperature and thermal output of these magnetic particles is necessary to gauge overall heating efficiency and to provide a more holistic understanding of heat transfer on the nanoscale. Herein, this dissertation seeks to develop a novel nanoparticle thermometry technique, which correlates diffusion behavior in core-shell nanoparticles to local temperature. Initial measurements suggested that heating silica capped ferrous nanoparticles (SCNPs) via …

Study Of Thick Indium Gallium Nitride Graded Structures For Future Solar Cell Applications, Manal Abdullah Aldawsari

Graduate Theses and Dissertations

Indium gallium nitride (InxGa1-xN) materials have held great potential for the optoelectronic industry due to their electrical and optical properties. The tunable band gap that can span the solar spectrum was one of the most significant features that attracted researchers’ attention. The band gap can be varied continuously from 0.77 eV for InN to 3.42 eV for GaN, covering the solar spectrum from near infrared to near ultraviolet. Additionally, it has a high absorption coefficient on the order of ∼105 cm−1, a direct band gap, high radiation resistance, thermal stability, and so on. Nevertheless, the epitaxial growth of high quality …

Incorporation Of Zinc In Pre-Alloyed Cuin[Zn]S2/Zns Quantum Dots, Jean Carlos Morales Orocu

Graduate Theses and Dissertations

Since the early 2000s heavy-metal-free quantum dots (QDs) such as CuInS2/ZnS have attempted to replace CdSe, their heavy-metal-containing counterparts. CuInS2/ZnS is synthesized in a two-step process that involves the fabrication of CuInS2 (CIS) nanocrystals (NCs) followed by the addition of zinc precursors. Instead of the usual core/shell architecture often exhibited by binary QDs, coating CIS QDs results in alloyed and/or partially alloyed cation-exchange (CATEX) QDs. The effect that zinc has on the properties of CIS NCs was studied by incorporating zinc during the first step of the synthesis. Different In:Cu:Zn ratios were employed in this study, maintaining a constant 4:1 …

Multifunctional Programmable Self-Assembled Nanoparticles In Nanomedicine, Yoshie Sakamaki

Graduate Theses and Dissertations

Developing methodologies to control the architecture of nanoparticles (NPs) at the atomic level prevents their inhomogeneity and leads to a variety of expected functions. Rationally designed nanoparticles can either be programmed or crystallized structures into pre-determined structures achieving tunable particle pore size and physiochemistry. In this dissertation, two broad classes of multifunctional nanoparticles are developed, metal-organic frameworks and DNA-NP aggregates.

Metal-organic frameworks are a novel class of highly porous crystalline materials built from organic linkers and metal cluster-based secondary building units. However, applications in bioremediation have not been developed very well especially in applications regarding drug delivery systems (DDS). The …

Synthesis Of Polyethylene Glycol-Based Hydrogels And Silver/Gold Nanostructures For Biomedical Applications, Isabelle Ishimwe Niyonshuti

Graduate Theses and Dissertations

This work focuses on the synthesis of biocompatible polyethylene glycol (PEG)-based hydrogels, silver nanoparticles (AgNPs), and silver-gold nanocages (Ag-AuNCs) for biomedical applications. The dissertation includes two parts with Part I on the work of PEG-based hydrogel for wound healing applications and Part II on the work of Ag/Au nanostructures for antimicrobial applications. Part I studies PEG-based hydrogel for the delivery of fibroblast growth factors (FGFs) for wound healing applications, aiming to overcome the challenge of designing hydrogels capable of the sustained release of bioactive FGFs. This research develops new biocompatible anionic injectable hydrogel formulations based on Poly (Oligo Ethylene Glycol …

Recombinant Production And Purification Of Green Fluorescent Protein (Gfp)-Fused Metal Binding Protein For Palladium Nanoparticle Synthesis, Shadrach Ibinola

Graduate Theses and Dissertations

In lieu of chemical and physical methods, biologically guided synthesis is increasingly used as a cost-effective medium for the fabrication of nanoparticles (NP). Recently, a palladium metal binding sequence Pd4 (TSNAVHPTLRHL) has been demonstrated to be instrumental in the production of palladium (Pd) nanoparticles. Although, by eliminating the additional cost of purification of the protein, the crude lysate of E. coli containing Pd specific protein has been proven to be a viable cost-effective means for the synthesis of Pd NP, studies have not be done to ascertain the comparative catalytic activity of nanoparticles synthesized from both clarified lysate and pure …

Investigation Of Iron-Nickel Based Nanoparticles As Catalysts For Oxygen Evolution Reaction (Oer), Prashant Acharya

Graduate Theses and Dissertations

Hydrogen fuel is increasingly seen as an appealing alternative by both the scientific and the industrial communities in the drive towards a clean energy future. Hydrogen, unlike fossil-based fuels, does not release carbon dioxide, a chief component of greenhouse gases, upon combustion. However, more than 95% of the hydrogen in the world is still produced by burning fossil fuels as this method is currently the only economically feasible option at a large industrial scale.

Water electrolysis shows a lot of potential in both hydrogen generation and in the storage of energy from renewable sources such as wind and sunlight. Likewise, …

Fabrication And Characterization Of Photodetector Devices Based On Nanostructured Materials: Graphene And Colloidal Nanocrystals, Wafaa Gebril

Graduate Theses and Dissertations

Photodetectors are devices that capture light signals and convert them into electrical signals. High performance photodetectors are in demand in a variety of applications, such as optical communication, security, and environmental monitoring. Among many appealing nanomaterials for novel photodetection devices, graphene and semiconductor colloidal nanocrystals are promising candidates because of their desirable and unique properties compared to conventional materials.

Photodetector devices based on different types of nanostructured materials including graphene and colloidal nanocrystals were investigated. First, graphene layers were mechanically exfoliated and characterized for device fabrication. Self-powered few layers graphene phototransistors were studied. At zero drain voltage bias and room …

An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan

Graduate Theses and Dissertations

Friction tests are a beneficial means to analyze the tribological characteristics and advantages of materials and textured surfaces. However, the selected test parameters can significantly influence the results. This work explores the significance of the friction testing parameters on the frictional performances of core-shell nanostructure-textured surfaces (CSNTSs). Several applied normal loads (10 μN, 100 μN, and 500 μN) and diamond counterface indenter tip radii (1 μm, 5 μm, and 20 μm) were selected for the testing of Al/diamond-like-carbon (DLC) and Al/amorphous silicon (a-Si) CSNTSs. The measured friction values of the CSNTSs were then compared to a matching Al/DLC film and …

Characterization Of Protein Aggregation Using A Solid-State Nanopore Device, Mitu Chandra Acharjee

Graduate Theses and Dissertations

Protein aggregation has been linked to many chronic and devastating neurodegenerative human diseases and is also strongly associated with aging. In the case of neurodegenerative diseases, α, β tubulins and tau proteins dissociate in a neuron cell and aggregate both intra and extra-cellularly. Tau and tubulin aggregations were found as one of the major causes of many neurodegenerative diseases, such as Parkinson’s, Picks, Alzheimer’s, Huntington, and Prion. Finding the state and mechanism of protein aggregation is significant. In this work, tau and tubulin aggregations were detected in ionic solutions using the solid-state nanopore technique. Besides tau and tubulin, aggregations of …

Oxone® Mediated Tempo-Oxidized Cellulose Nanomaterials: Material Characterization, Ultrafiltration Membrane Separations, And Thin Film Composite Gas Transport Analysis, John Phillips Moore

Graduate Theses and Dissertations

Cellulose nanomaterials (CNMs) are derived from plant matter and are comprised of nanoscopic cellulose crystals and fibers. They have a diverse set of applications, from cosmetics to oil recovery. This study focuses on the properties of Oxone® mediated TEMPO-oxidized cellulose nanomaterials (OTO-CNMs) and their use in controlling the transport properties of polymeric substrates. Synthesis and characterization of cellulosic nanoparticles have resulted in the creation of OTO-CNMs with properties that increase hydrophilicity. With added hydrophilicity, OTO-CNMs possess lower fouling propensity, making them ideal membrane additive for transport limited separations such as hemodialysis.

To utilize the material and unique properties thereof, this …

The Varied Thermal Response Of Magnetic Iron-Oxide Nanoparticles During Induction Heating In Liquid And Solid-Liquid Phase Change Mediums, Joshua Tompkins

Graduate Theses and Dissertations

This study investigates the induction heating response of uncapped iron oxide nanoparticles sonically dispersed as a nanofluid and mechanically distributed in solid phase change materials. The nanoparticles examined have a mean diameter of 14.42 nm and are magnetically heated in an alternating magnetic field at an amplitude of 72.6 kA/m at frequencies of 217, 303, and 397 kHz. Nanoparticle characterization was undertaken through transition electron microscopy, x-ray diffraction, and dynamic light scattering when in suspension. Carrier fluids were characterized through viscosity, heat capacity, and density measurements which were used in the calorimetric calculation of the specific absorption rate (SAR) of …

Development And Characterization Of Metal Contacts For Graded Composition Ingan Solar Cells, Reem E. Alhelais

Graduate Theses and Dissertations

There is an increasing demand for high-power electronic components and optoelectronic devices with low-loss and high efficiency. III-nitride semiconductor materials have demonstrated great potential for high-power, high-frequency, and high-temperature applications because of their remarkable and wide-ranging electronic and physical properties. These material systems, including alloys of AlN, GaN, and InN, are currently being explored for their potential to develop efficient photovoltaic cells. They can potentially achieve higher efficiency because of their very high direct wide band edge, absorption coefficients, and resistance to defects. The compositionally graded Group III-nitride alloy allows access to a large range of energies by varying the …

Optical Properties Of Ultrathin In(Ga)As/Gaas And In(Ga)N/Gan Quantum Wells, Yurii Maidaniuk

Graduate Theses and Dissertations

Recently, structures based on ultrathin quantum wells (QWs) began to play a critical role in modern devices, such as lasers, solar cells, infrared photodetectors, and light-emitting diodes. However, due to the lack of understanding of the formation mechanism of ultrathin QWs during the capping process, scientists and engineers cannot fully explore the potential of such structures. This study aims to investigate how structural parameters of ultrathin QWs affect their emission properties by conducting a systematic analysis of the optical properties of In(Ga)As/GaAs and In(Ga)N/GaN ultrathin QWs. Specifically, the analysis involved photoluminescence measurements combined with effective bandgap simulation, x-ray diffraction, and …

Applications Of Cathodoluminescence In Plasmonic Nanostructures And Ultrathin Inas Quantum Layers, Qigeng Yan

Graduate Theses and Dissertations

Due to the advanced focusing ability, characterization methods based on the electron-beam excitation have been broadly applied to investigate nanomaterials. Structural or compositional information is commonly acquired using electron microscopes. Moreover, taking advantage of the super spatial resolution of the focused electron beam, optical properties of nanomaterials can be also obtained. Herein, general concepts and processes of the interaction between electrons and materials are studied. Two specific optical nanomaterials, including plasmonic nanostructures and semiconductor quantum layers, are investigated by the cathodoluminescence (CL) measurement.

Surface plasmonic resonance can be generated when high-energy electrons strike the interface between the dielectric medium and …

Characterization Of Avidin And Case9 Single Protein Molecules By A Solid-State Nanopore Device, Haopeng Li

Graduate Theses and Dissertations

The shape and charge of a protein play significant roles in protein dynamics in the biological system of humans and animals. Characterizing and quantifying the shape and charge of a protein at the single-molecule level remains a challenge. Solid-state nanopores made of silicon nitride (SiNx) have emerged as novel platforms for biosensing such as diagnostics for single-molecule detection and DNA sequencing. SSN detection is based on measuring the variations in ionic conductance as charged biomolecules translocate through nanometer-sized channels driven by an external voltage applied across the membrane. In this paper, we observe the translocation of asymmetric cylindrical structure CRISPR-Cas9 …

Optimized Production And Evaluation Of Cellulose Nanocrystals Derived From Pre-Extracted Kraft Pulp Of Different Wood Species, Gurshagan Kandhola

Graduate Theses and Dissertations

Production of nanocellulose from a variety of naturally abundant, locally available and industrially significant wood species provides an opportunity for diversifying the portfolio of traditional pulp and paper industries. The U.S. has a prolific forest products industry with a well-established infrastructure that could be utilized for optimized and customized production of cellulose nanomaterials. However, to achieve that, it is important to a) understand how biorefining strategies for complete fractionation of biomass affect the downstream processing of pulp into nanocellulose, b) maximize the yields of cellulose nanocrystals and nanofibers (CNCs and CNFs) from pretreated raw materials, and c) evaluate if the …

Studies Of Initial Growth Of Gan On Inn, Alaa Alnami

Graduate Theses and Dissertations

III-nitride materials have recently attracted much attention for applications in both the microelectronics and optoelectronics. For optoelectronic devices, III-nitride materials with tunable energy band gaps can be used as the active region of devices to enhance the absorption or emission. A such material is indium nitride (InN), which along with gallium nitride (GaN) and aluminum nitride (AlN) embody the very real promise of forming the basis of a broad spectrum, a high efficiency solar cell. One of the remaining complications in incorporating InN into a solar cell design is the effects of the high temperature growth of the GaN crystal …

Synthesis Of Cellulose Nanocrystal-Gold Nanoparticle Hybrid System For Surface Plasmon-Enhanced Property, Mahshid Iraniparast

Graduate Theses and Dissertations

Gold nanoparticles (AuNPs) have been brought to the forefront of various applications, ranging from theranostics, to organic photovoltaics, to biosensing owing to their localized surface plasmon resonance (LSPR) property. However, this property needs to be improved in order to allow for high sensitivity and quantitative detection of biomolecules. Hybrids of AuNPs with low-dielectric cellulose nanocrystal (CNCs) would yield enhancement of the LSPR property, which is driven by the confinement of electron oscillation at their interfaces. This study proposed a seed-mediated growth method to synthesize hybrids of CNCs-AuNPs. Sulfate groups on the surface of CNCs served as the sites for the …

Quantitative Study Of The Antimicrobial Effects Of Silver On The Motility Of Escherichia Coli, Benjamin Russell

Graduate Theses and Dissertations

In recent decades, the number of antibiotic-resistant bacterial infections has grown to become a serious global threat. This rise can be attributed to the widespread misuse of antibiotics and the lack of newly developed drugs to fight resistant organisms. Novel bactericidal substances have, therefore, garnered significant research interest. Silver, due to its powerful antimicrobial effects, is one such substance. Silver is typically most effective in cationic form; however, advancements in nanotechnology have paved the way for the controlled fabrication of nano-silver. Silver nanoparticles have been shown to have increased antibacterial potency for a variety of reasons, including the release of …

A Study Of Protein And Peptide-Directed Nanoparticle Synthesis For Catalytic Materials, Abdollah Mosleh

Graduate Theses and Dissertations

Nanoparticles have received much attentions due to their unique properties that makes them suitable candidates for a broad range of applications. As the size of particles decreases, their surface area-to-volume ratio would increase which is the main cause of much attention. In addition to the size, their morphologies and compositions may also play important roles for defining unique properties. Nanoparticle synthesis include both bottom-up and top-down strategies. To control the process of inorganic nanoparticles synthesis one could follow the bottom-up approach to have atom-level control over their compositions, morphologies, phases, and sizes which is the subject of this work. Due …

The Role Of Inter-Particle Behavior In Iron Oxide Nanoparticle Induction Heating, Hayden Seth Carlton

Graduate Theses and Dissertations

Due to their multi-functional nature, iron oxide nanoparticles present themselves in a myriad of scientific disciplines, but perhaps the most interesting property of these nanomaterials can be seen in their immense thermal response under the influence of alternating magnetic fields. Currently popularized as an alternative cancer treatment through localized hyperthermia, iron oxide nanoparticle induction heating presents an interesting physical phenomenon that distinguishes itself from macroscopic induction heating. Understanding how a single spherical particle behaves is relatively simple and remains well documented; however, magnetic interactions of a single particle often extend over many length scales, affecting numerous neighboring particles in the …

Self-Assembled Nanoantenna Enhance Optical Activity And Transport In Scalable Thin Films And Interfaces, Keith Richard Berry Jr.

Graduate Theses and Dissertations

Continued population growth and the decrease of existing energy platforms demands long-term solutions for development and implementation of scalable plasmonic metamaterials for energy and agricultural applications. Self-assembled nanoantenna into random and ordered arrangements are advanced herein for optical and thermal enhancements in scalable thin film. An analytical approach to estimating the thermal dynamics of random arrangements of nanoantenna resulted in estimates within 30% across a range of geometric parameters, nanoantenna-containing media, and thermal parameters. Multimodal thermal dynamics of polymer thin films containing gold nanoparticles (AuNPs) were observed through the natural log of the dimensionless temperature driving force plotted versus time …

Experimental And Computational Study On Magnetic Nanowires Of Layered Titanates, Caleb Layne Heath

Graduate Theses and Dissertations

The intricate nanostructures of layered titanates are unique among nanomaterials due to their easy and inexpensive syntheses. These nanomaterials have been proven valuable for use in industries as varied as energy, water treatment, and healthcare, and can be produced at industrial scales using already existent equipment. They have complex morphology, and surface structure well suited to chemical modification and doping. However, there is a longstanding debate on their lattice structure after the doping. There is a long-unmet need to understand, using both experimental and simulation methods, how dopants alter the clay-like layered crystal structure and associated physical and chemical properties. …