Physical Sciences and Mathematics Commons^™

Hydrophobically Modified Isosorbide Dimethacrylates As Biomaterials For Bisphenol A Free Dental Fillings, Bilal Marie

Dissertations

Amalgam and Bisphenol A glycerolate dimethacrylate (BisGMA) are the main dental filling materials in use today. Because of the negative perception of amalgam and its lower esthetic appeal, as well as the desire to replace the endocrine disruptor Bisphenol A, which is the building block of BisGMA, there has been a critical need to search for safer alternatives to these dental filling materials.

Isosorbide is a sugar-based molecule generally recognized as safe. It has been extensively studied as a replacement to the Bisphenol A core in various materials. However, isosorbide is extremely hygroscopic, and water uptake in dental fillings causes …

Experimental And Computational Studies Of Functionalized Carbon Nanotubes For Use In Energy Storage Devices And Membranes, Emine S. Karaman

Dissertations

Electrolytes with good interfacial stability are a crucial component of any electrochemical device. The development of novel gel polymer electrolytes (GEs) with good interface stability and better manufacturability is important for the development of the next generation electrochemical devices. Gel electrolytes are hybrid electrolyte materials, combining benefits of both liquid and solid systems. Compared with liquid and solid electrolytes, GEs open new design opportunities and do not require rigorous encapsulation methods. In this dissertation, studies on functionalized carbon nanotubes (fCNTs) and graphene oxide (GO) doped polyvinyl alcohol (PVA) based gel electrolytes (GEs) are reported. The ionic conductivity and mechanical strength …

Electric-Field-Driven Processes In Multiphase Fluid Systems, Qian Lei

Dissertations

Advantages of using electric fields in miniaturized apparatuses for a wide range of applications are revealed by numerous experimental and theoretical studies over the last several decades as it offers a simple and efficient method for manipulation of multiphase fluid systems. This approach is considered to be especially beneficial for control of boiling processes and colloidal suspensions considered in the presented work.

Boiling. Today's trends for enhancing boiling heat transfer in terrestrial and space applications focus on removal of bubbles to prevent formation of a vapor layer over the surface at a high overheat. In contrast, this dissertation presents a …

Interfaces And Dynamics In Polymeric 3d Printing And Crystalline Polymer Blends, Stevenson C. Perryman

Doctoral Dissertations

This dissertation presents experimental work that provide a foundation to rationally improve fused filament fabrication (FFF) and immiscible blend compatibilization. Objects generated from additive manufacturing processes, such as FFF, have intrinsic structural weaknesses which include two project specific examples: structural anisotropy and irreversible thermal strain. Due to low adhesion between individual print layers that results in macroscopic defects, the mechanical strength of printed objects when force is applied perpendicular to the build orientation is drastically reduced. In the first dissertation chapter, we present a protocol to produce interlayer covalent bonds by depositing multi-amine additives between individual layers of a print …

Dreams Of Molecular Beams: Indium Gallium Arsenide Tensile-Strained Quantum Dots And Advances Towards Dynamic Quantum Dots (Moleculare Radiorum Somnia: Indii Gallii Arsenicus Tensa Quanta Puncta Et Ad Dinamicae Quantae Puntae Progressus), Kevin Daniel Vallejo

Boise State University Theses and Dissertations

Through the operation of a molecular beam epitaxy (MBE) machine, I worked on developing the homoepitaxy of high quality InAs with a (111)A crystallographic orientation. By tuning substrate temperature, we obtained a transition from a 2D island growth mode to step- ow growth. Optimized MBE parameters (substrate temperature = 500 °C, growth rate = 0.12 ML/s and V/III ratio ⩾ 40) lead to growth of extremely smooth InAs(111)A films, free from hillocks and other 3D surface imperfections. We see a correlation between InAs surface smoothness and optical quality, as measured by photoluminescence spectroscopy. This work establishes InAs(111)A as a platform …

Hybrid Two Dimensional Quantum Devices, Joshua Patrick Thompson

Graduate Theses and Dissertations

This thesis describes measurements on hybrid material systems involving two dimensional (2D) materials and phenomena along with the development of a small, hermetically sealed cell. The hermetic cell is designed to assist with analyzing sensitive 2D materials outside of an inert environment. When working with van der Waals materials that are especially sensitive to oxygen or water, it can be difficult to identify usable thin flakes without exposing them to air. To help preserve materials for analysis in air, a capsule was designed that isolates the material in an inert environment. Although the capsule is hermetically sealed, the encapsulated material …

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 …

Synthesis, Crystal Structure And Ionic Conductivity Of Ruddlesden-Popper Oxide Materials: Effects Of Ionic Radii And Defects On Lithium-Ionic Conductivity., Selorm Joy Fanah

Electronic Theses and Dissertations

Layered perovskite oxides of the Ruddlesden-Popper (RP) type structure can be good lithium-ion conductors for solid electrolyte applications in all-solid-state batteries, due to the large gap separating octahedral layers which can be useful pathways for Li-ion conduction. However, little work has been done on their lithium-ion transport properties in these materials despite their interesting structural properties. This work highlights the synthesis and study of the ionic conductivities in a series of n = 2 and 3 Ruddlesden-Popper oxides, as part of an ongoing investigation in search of alternative solid electrolyte materials. Several different strategies were employed for the enhancement of …

Functional Material Systems For Stimuli-Responsive Interference Coloration, Milad Momtaz

Theses and Dissertations

Part I: Responsive Interference Coloration (RIC) Systems for High-Performance Humidity Sensing

High-humidity conditions (85−100% relative humidity) have a variety of effects on many aspects of our daily lives. In spite of significant progress in the development of structural coloration-based humidity sensors, enhancing the sensitivity and visual humidity resolution of these sensors at high-humidity environment remains a big challenge. In this work, high-performance colorimetric humidity sensors based on environment-friendly konjac glucomannan (KGM) are introduced. These sensors are fabricated via thin-film interference and prepared using a simple, affordable, and scalable method. An effective approach is shown for markedly improving the sensitivity and …

Two-Dimensional Black Phosphorus For Terahertz Emission And Near-Field Radiative Heat Transfer, Mahmudul Hasan Doha

Graduate Theses and Dissertations

The main focus of this work is to investigate two potential optical and optoelectronic applications of black phosphorus (BP): the near-field radiative heat transfer in plasmonic heterostructures with graphene and terahertz emission from multi-layer BP photoconductive antennas. When the separation distance between graphene-black phosphorene is much smaller than or comparable to the thermal wavelength at different temperatures, a near-field radiation heat transfer breaks the Planck blackbody limit. The magnitude of the near-field radiation enhancement acutely depends on the gate voltage, doping, and vacuum gap of the graphene and BP pair. The strong near-field radiation heat transfer enhancement of the specific …

Reliability Characterization Of A Low-K Dielectric Using Its Magnetoresistance As A Diagnostic Tool, Philip Alister Williams

Legacy Theses & Dissertations (2009 - 2024)

The introduction of low dielectric constant materials within the integrated circuit (IC) chip technology industry was a concerted effort to decrease the resistance-capacitance (RC) time delay inherent within the dielectric materials used as insulators. This stems from a demand for greater device density per IC chip and decreased feature sizes but is fast becoming a reliability issue. Concomitant with the demand for decreased feature sizes, also in adherence with Moore’s Law (which states that the number of devices on a die doubles every two years), is a reduction in device speed and performance due to device intra-level interconnection signal delays. …

Investigation Of Optical And Structural Properties Of Gesn Heterostructures, Oluwatobi Gabriel Olorunsola

Graduate Theses and Dissertations

Silicon (Si)-based optoelectronics have gained traction due to its primed versatility at developing light-based technologies. Si, however, features indirect bandgap characteristics and suffers relegated optical properties compared to its III-V counterparts. III-Vs have also been hybridized to Si platforms but the resulting technologies are expensive and incompatible with standard complementary-metal-oxide-semiconductor processes. Germanium (Ge), on the other hand, have been engineered to behave like direct bandgap material through tensile strain interventions but are well short of attaining extensive wavelength coverage. To create a competitive material that evades these challenges, transitional amounts of Sn can be incorporated into Ge matrix to form …

Synthesis And Characterization Of 4,6-Protected Glucosamine Derivatives And Branched Glycoconjugates, Jonathan Bietsch

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are small molecules that self-assemble in appropriate solvents to form three dimensional networks that immobilize the solvent, creating a supramolecular gel. The self-assembly of LMWGs occurs through non-covalent interactions such as hydrogen bonding, aromatic interactions, donor-acceptor interactions, Van der Waals interactions, hydrophobic forces, halogen bonding, etc. Due to self-assembly occurring through reversible non-covalent interactions, supramolecular gels can undergo a gel to solution transformation. Because of this, these materials can be sensitive to external stimuli such as temperature changes, pH changes, and other stimuli that effect non-covalent interactions. This makes the synthesis of LMWG’s an appealing …

Interferometric Lithography- An Approach To Large Area And Cost Effective Nanopatterning, Vineeth Sasidharan

Optical Science and Engineering ETDs

In this dissertation interferometric lithography is approached in two different ways to address two important constraints of nanopatterning. One approach solves the problem of scaling up interferometric lithography to wafer scale (4 inch or larger) area. Through the second approach we have developed a nanopatterning technique based on interferometric lithography by using an inexpensive (~$100) diode laser as source, making interferometric lithography a very cost-effective technique.

Wafer-scale large-area nanopatterning was developed using an amplitude grating mask as a grating beam splitter along with spatial averaging of laser intensity by wobbling. The longitudinal and transverse coherence issues both are eased by …

Crystal Structure Prediction Of Materials At Extreme Conditions, Ashley S. Williams

USF Tampa Graduate Theses and Dissertations

The prediction of the structure of a crystal given only the constituent elements is one of the greatest challenges in both materials science and computational science alike. If one were to try to predict a novel crystal by brute force, meaning by arranging the atoms in every possible position of the unit cell and optimizing the geometry to find the energy minima of the potential energy surface, the amount of computer resources required to complete the calculation on the timescale of a few years would vastly exceed the currently installed computational capacity of the entire world. Fortunately, several methods have …

The Photophysical Studies Of Transition Metal Polyimines Encapsulated In Metal Organic Frameworks (Mof’S), Jacob M. Mayers

USF Tampa Graduate Theses and Dissertations

Light harvesting systems provide a platform that converts solar energy into other forms of energy. One of the most common examples of photon capturing and conversion into chemical energy is observed in photosynthetic organisms in both Eurkaroyic and Prokaryotic domains. Nature provides a model for successful light harvesting platforms which includes the compartmentalization of antenna complexes that contain separated donor and acceptor pairs that participate in efficient electron transfer processes. In order to mimic such systems, crystalline porous materials that exhibits regular cavities and pore dimensions provides an excellent starting place. Metal organic frameworks (MOFs) are a class of porous …

Investigation Of Immobilized Enzymes In Confined Environment Of Mesoporous Host Matrices, Xiaoliang Wang

USF Tampa Graduate Theses and Dissertations

Enzyme immobilization in metal-organic frameworks (MOFs) as a promising strategy, is attracting the interest of scientists from different disciplines with the expansion of MOF’s development. Different from other traditional host materials, their unique strengths of high surface areas, large yet adjustable pore sizes, functionalizable pore walls, and diverse architectures make MOFs an ideal platform to investigate hosted enzymes, which is critical to the industrial and commercial process. In addition to the protective function of MOFs, the extensive roles of MOFs in the enzyme immobilization are being well-explored by making full use of their remarkable properties like well-defined structure, high porosity, …

Texturing In Bi2Te3 Alloy Thermoelectric Materials: An Applied Physics Investigation, Oluwagbemiga P. Ojo

USF Tampa Graduate Theses and Dissertations

Thermoelectric devices provide the means for direct conversion between heat and electricity. The device conversion efficiency, or performance, is directly related to the thermoelectric figure of merit, ZT, of the working materials. Bismuth telluride alloys are the materials currently in use in most thermoelectric devices for near room temperature solid-state refrigeration and power conversion applications. The vast majority of publications in the literature on thermoelectricity report on investigations towards developing new materials with enhanced thermoelectric properties, however Bi₂Te₃ alloys have been used in thermoelectric devices for decades.

In this thesis, an investigation of crystallographic texturing on large …

Advanced Materials Design Using Application-Based Processing Techniques, Daniel S. Camarda

Doctoral Dissertations

This dissertation pertains to generating advanced materials using application-based processing techniques. First, billets consisting of PTFE sintering powders are evaluated using Thermomechancal Analysis. It was found that both shape change and volume change are associated with enthalpic and entropic recoil, respectively. These phenomena, due to melting and stored energy during the powder compaction process, were found to be molecular weight dependent. Additionally, kinetics of the recovery and sintering process were found to be slower in blended specimens than pure samples. Next, the creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi-crystalline polymer …

Chitosan Graphene Composite Fabrication And Characterization For Treatment Of Harmful Algal Blooms And Toxins, Sarah Zetterholm

Master's Theses

Chitosan graphene composites were fabricated and characterized as a management strategy for harmful algal blooms (HABs) caused by various species of cyanobacteria. These chitosan graphene materials were compared to previously studied chitosan graphene-oxide composites in both material properties and HAB treatment. In previous studies, adsorption of the cyanobacteria onto the surface of the composite materials has been observed. Investigations of the pure materials for these composites are also included in this study to determine whether removal is a result of charge interactions with the composite, or as an inherent property of the graphene or graphene oxide. Initial results suggest that …

Tools And Strategies For The Patterning Of Bioactive Molecules And Macromolecules, Daniel J. Valles

Dissertations, Theses, and Capstone Projects

Hypersurface Photolithography (HP) is a printing method for fabricating structures and patterns composed of soft materials bound to solid surfaces and with ~1 micrometer resolution in the x, y, and z dimensions. This platform leverages benign, low intensity light to perform photochemical surface reactions with spatial and temporal control of irradiation, and, as a result, is particularly useful for patterning delicate organic and biological material. In particular, surface- initiated controlled radical polymerizations can be leveraged to create arbitrary polymer and block- copolymer brush patterns. Chapter 1 will review the advances in instrumentation architectures from our group that have made these …

Molecular Dynamics Simulations Of Self-Assemblies In Nature And Nanotechnology, Phu Khanh Tang

Dissertations, Theses, and Capstone Projects

Nature usually divides complex systems into smaller building blocks specializing in a few tasks since one entity cannot achieve everything. Therefore, self-assembly is a robust tool exploited by Nature to build hierarchical systems that accomplish unique functions. The cell membrane distinguishes itself as an example of Nature’s self-assembly, defining and protecting the cell. By mimicking Nature’s designs using synthetically designed self-assemblies, researchers with advanced nanotechnological comprehension can manipulate these synthetic self-assemblies to improve many aspects of modern medicine and materials science. Understanding the competing underlying molecular interactions in self-assembly is always of interest to the academic scientific community and industry. …

Improvements To Emissive Plume And Shock Wave Diagnostics And Interpretation During Pulsed Laser Ablation Of Graphite, Timothy I. Calver

Theses and Dissertations

This dissertation covers nanosecond pulsed laser ablation of graphite for 4-5.7 J/cm² fluences with 248 nm and 532 nm lasers in 1-180 Torr helium, argon, nitrogen, air, and mixed gas. Three experiments were performed to improve the interpretation of common diagnostics used to characterize pulsed laser ablation, find simple but universal scaling relationships for comparing dynamics across different materials and ablation conditions, and provide a systematic analysis of graphite emissive plume and shock wave dynamics. A scaling of the Sedov-Taylor energy ratio was developed and validated for a range of studies despite differences in wavelength, pulse duration, fluence, and …

Laser Surface Treatment And Laser Powder Bed Fusion Additive Manufacturing Study Using Custom Designed 3d Printer And The Application Of Machine Learning In Materials Science, Hao Wen

LSU Doctoral Dissertations

Selective Laser Melting (SLM) is a laser powder bed fusion (L-PBF) based additive manufacturing (AM) method, which uses a laser beam to melt the selected areas of the metal powder bed. A customized SLM 3D printer that can handle a small quantity of metal powders was built in the lab to achieve versatile research purposes. The hardware design, electrical diagrams, and software functions are introduced in Chapter 2. Several laser surface engineering and SLM experiments were conducted using this customized machine which showed the functionality of the machine and some prospective fields that this machine can be utilized. Chapter 3 …

Development Of Advanced Solid-State Electrolytes And Interfaces For High-Performance Sulfide-Based All-Solid-State Lithium Batteries, Feipeng Zhao

Electronic Thesis and Dissertation Repository

All-solid-state lithium batteries (ASSLBs) have become increasingly attractive due to the demand of high-energy-density and high-safety lithium-ion batteries for electric vehicles (EVs). As the core component of ASSLBs, solid-state electrolytes (SSEs) are regarded as essential to determine the electrochemical performance of ASSLBs. The inorganic SSEs is one of the most important categories in all developed SSEs, representing the advance of superionic lithium conductors as well as the cornerstone to construct flexible polymer/inorganic composite SSEs. The sulfide-based inorganic SSE is one of the most promising SSEs that is receiving a lot of attentions, because only sulfide SSEs can show ultrahigh ionic …

Characterization Techniques And Cation Exchange Membrane For Non-Aqueous Redox Flow Battery, Kun Lou

Doctoral Dissertations

The motivation of this work comes from one of the major problems of emerging non-aqueous flow battery (NAFB) that a separator or membrane which facilitates conductivity and blocks redox species crossover does not exist. Although many aspects of principles can be mirrored from mature fuel cell and aqueous flow battery, it is found that some well-defined membrane properties in aqueous systems such as swelling, transport and interactions are different in non-aqueous solvents to some extent. However, the approach of this work does follow the way perfluorosulfonate ion exchange membrane (PFSA) facilitated development of fuel cell and aqueous flow battery in …

Development Of Density-Functional Tight-Binding Methods For Chemical Energy Science, Quan Vuong

Doctoral Dissertations

Density-functional tight-binding (DFTB) method is an approximation to the popular first-principles density functional theory (DFT) method. Recently, DFTB has gained considerable visibility due to its inexpensive computational requirements that confer it the capability of sustaining long-timescale reactive molecular dynamics (MD) simulations while providing an explicit description of electronic structure at all time steps. This capability allows the description of bond formation and breaking processes, as well as charge polarization and charge transfer phenomena, with accuracy and transferability beyond comparable classical reactive force fields. It has thus been employed successfully in the simulation of many complex chemical processes. However, its applications …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Preparation And Characterization Of Single Layer Conducting Polymer Electrochromic And Touchchromic Devices, Sharan Kumar Indrakar

USF Tampa Graduate Theses and Dissertations

Electrochromic devices (ECDs) have triggered great interest because of their potential applicability in energy-efficient buildings and low power display systems, including reflective type smart windows/mirrors and wearable-flexible devices. In the past decades, electrochromic technologies with different device structures and materials have been proposed. The idea of employing a simple device structure with a durable, cost effective electrolyte is crucial to designing and manufacturing high-performance ECDs. With this idea in mind, this thesis describes the various efforts to develop a simple ECD comprising of a composite single active layer gel electrolyte, sandwiched between two transparent conducting electrodes, lasting over 10,000 cycles …

Designing Stimuli-Responsive Nanocomposites To Investigate Interface Dynamics, Huyen Vu

Doctoral Dissertations

Inspired by nature, this research focuses on designing multifunctional renewable nanocomposites with high toughness and stimuli-responsiveness. In recent years, cellulose nanocrystals (CNCs) have been explored due to their abundance, renewable resource, and unique mechanical strength and structural coloration. CNCs naturally self-assemble into the helicoidal (Bouligand) structure that effectively endure high impacts but is brittle without an attendant soft phase. A thermoresponsive polymer, poly(diethylene glycol methyl ether methacrylate) (PMEO₂MA), was incorporated into CNCs via evaporation-induced self-assembly to improve toughness of the resulting nanocomposites and to study responses in polymer dynamics under varying temperature and humidity conditions. To study microscopic …