Engineering Commons^™

Mechanical Behavior Of Ternary Metallic Glasses And Their Composites, Xue Liang

FIU Electronic Theses and Dissertations

The vast demands for advanced materials have been putting tremendous pressure on materials scientists and engineers to discover and produce novel lighter and stiffer materials. This dissertation is devoted to the development and fundamental understanding of the strength and the structures within Aluminum ternary metallic glasses (MGs) and their composites, which have a low density and promising high strength. The dissertation focuses on the following content: The multi-objective optimization algorithm predicted the Al_16.5Ni₈Ce_75.5 ternary metallic glass composition with an improved glass-forming ability (supercooled liquid region ∆����=29K), based on the provided dataset. Inoue Criteria can predict …

Graphene Foam Reinforced Shape Memory Polymer Epoxy Composites, Adeyinka Idowu

FIU Electronic Theses and Dissertations

Shape memory polymer (SMP) epoxy has received growing interest due to its facile processing, low density, and high recoverable strain. Despite these positive attributes, SMP epoxy has drawbacks such as slow recovery rate, and inferior mechanical properties. The slow recovery rate restricts the use of SMP epoxy as a functional structure.

The aim of the present work is to explore the capabilities of three-dimensional (3D) graphene foam (GrF) and graphene nanoplatelet (GNP) as reinforcements in SMP epoxy to overcome their slow recovery and improve the mechanical properties. GrF and GNP based SMP epoxy composites are fabricated by mold-casting approach and …

High-Power Biofuel Cells Based On Threedimensional Reduced Graphene Oxide/ Carbon Nanotube Micro-Arrays, Yin Song, Chunlei Wang

Department of Mechanical and Materials Engineering

Miniaturized enzymatic biofuel cells (EBFCs) with high cell performance are promising candidates for powering next-generation implantable medical devices. Here, we report a closed-loop theoretical and experimental study on a micro EBFC system based on three-dimensional (3D) carbon micropillar arrays coated with reduced graphene oxide (rGO), carbon nanotubes (CNTs), and a biocatalyst composite. The fabrication process of this system combines the top–down carbon microelectromechanical systems (C-MEMS) technique to fabricate the 3D micropillar array platform and bottom–up electrophoretic deposition (EPD) to deposit the reduced rGO/CNTs/enzyme onto the electrode surface. The Michaelis–Menten constant KM of 2.1 mM for glucose oxidase (GOx) on the …

Lithium-Ion Hybrid Capacitor Devices: Towards High-Performance Electrochemical Capacitive Energy Storage, Ebenezer Dotun Adelowo

FIU Electronic Theses and Dissertations

Hybridization of lithium-ion batteries (LIBs) and electrochemical capacitors (ECs) at electrode level can potentially provide high-performance capacitive energy storage having a good combination of high energy density, high power density, and moderate cycling longevity. Lithium-ion hybrid capacitor (LIHC) system consisting of a battery-type anode and a capacitor-type cathode represents an attractive hybridization approach aimed at bridging the performance gap between the two energy storage systems. The application of such energy storage system may extend the functionalities of many electronic devices.

In this dissertation, different LIHC configurations were designed and evaluated. An LIHC device comprising electrostatically sprayed reduced graphene oxide (rGO)-based …

Towards Stable Electrochemical Sensing For Wearable Wound Monitoring, Sohini Roychoudhury

FIU Electronic Theses and Dissertations

Wearable biosensing has the tremendous advantage of providing point-of-care diagnosis and convenient therapy. In this research, methods to stabilize the electrochemical sensing response from detection of target biomolecules, Uric Acid (UA) and Xanthine, closely linked to wound healing, have been investigated. Different kinds of materials have been explored to address such detection from a wearable, healing platform. Electrochemical sensing modalities have been implemented in the detection of purine metabolites, UA and Xanthine, in the physiologically relevant ranges of the respective biomarkers. A correlation can be drawn between the concentrations of these bio-analytes and wound severity, thus offering probable quantitative insights …

Boron Nitride Nanotube Reinforced Titanium Composite With Controlled Interfacial Reactions By Spark Plasma Sintering, Jenniffer Bustillos

FIU Electronic Theses and Dissertations

In this study, Boron Nitride Nanotube (BNNT) reinforced Titanium matrix composites are synthesized by Spark Plasma Sintering. Two main challenges directly affecting the mechanical performance of BNNT-metal matrix composites are addressed:(i) Homogenous dispersion of high surface energy BNNTs, and (ii) Controlling interfacial reactions at the metal/nanotube interface. High-energy ultrasonication induced dispersion resulted in the functionalization of BNNTs by -OH radicals proving its suitability over surfactant assisted dispersion routes. The sintering of Ti (99% relative density) was achieved at 50% less processing temperature than those used in conventional sintering to minimize interfacial reactions when reinforced with BNNTs. The reduction of temperatures …

Spark Plasma Sintering Of 2d Nitride And Carbide Based Ceramics, Archana Loganathan

FIU Electronic Theses and Dissertations

Two-dimensional (2D) nanomaterials have stimulated significant interest among materials community due to a wide variety of application ranging from functional to structural properties. Boron nitride nanosheets (BNNS), boron-carbon-nitride (BCN), and MXene (M_n+1X_n, transition metal carbides, nitrides or carbonitrides) belongs to 2D materials family with van der Waals bonding between the layers. The research on synthesis and properties of BNNS, BCN and MXene have been predominantly explored for single- or multi-layered 2D nanosheets. In this study, the focus is to synthesize bulk layered BNNS and BCN using single or multilayered 2D nanomaterials by spark plasma sintering (SPS). …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

Mesoscale Ceramic Cylindrical Ion Trap Mass Analyzers For In Situ Sample Analysis, Patrick Roman

FIU Electronic Theses and Dissertations

As wireless network devices and IOT connectivity develop, the application and demand for small, low power, in situ sensors and instruments will expand. There are continuous efforts in the miniaturization of sensors and scientific instrument systems for conventional to field deployable and rugged hand held units for personal use to extreme harsh environment applications. This work investigates mesoscale cylindrical ion trap (CIT) mass analyzer design and the benefits of CITs realized via additive manufactured metalized ceramic material systems for improved ion signal, low power performance, and extended dynamic range. Rugged monolithic miniature mass spectrometer ceramic CIT chips have been produced …

The Effect Of Proteome And Lipidome On The Behavior Of Membrane Bound Systems In Thermally-Assisted Acoustophoresis, Elnaz Mirtaheri

FIU Electronic Theses and Dissertations

Changes in the biomechanical properties of cells accompanying the development of various pathological conditions have been increasingly reported as biomarkers for various diseases, including cancers. In cancer cells, the membrane properties have been altered compared to their healthy counterparts primarily due to proteomic and lipidomic dysregulations conferred by the underlying pathology. The separation and selective recovery of these cells or extracellular vesicles secreted from such cells is of high diagnostic and prognostic value.

In this dissertation, the research builds on thermally-assisted acoustophoresis technique which was developed in our laboratory for the separation of vesicles of the same size, charge and …