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Silver Doped Nanoceria (Agcnp) Integrated Silk Scaffold For Chronic Wound Healing, Architha K. Venkatesan

Honors Undergraduate Theses

Chronic wound healing can be seriously impeded by the formation of biofilms, infections, peri-wound edema, hematoma, osteomyelitis, and the formation of reactive oxidative species (ROS). We hypothesize that a scaffold created from Silver-Doped Nanoceria (AgCNP) embedding silk can be beneficial to aid the wound healing process, inhibit inflammation and prevent microorganisms from forming a biofilm over the wound. Current wound healing methods such as intradermal injections are not advantageous to use since they can cause unwanted responses elsewhere in the body other than the wound site. Silk, however, has a positive impact on the wound healing effect and can be …

Nanostructured Alloy Thin Film Fabrication And Application For Zinc-Air Battery And Lithium-Ion Battery, Guanzhi Wang

Electronic Theses and Dissertations, 2020-

The depletion of unsustainable fossil fuels and growing environmental issues have given rise to scientific challenges and research interests in the development of renewable energy technologies to meet the rising global energy demand. Electrochemical energy storage and conversion technologies (ESCTs), such as lithium-ion batteries, metal-air batteries, supercapacitors, and fuel cells, etc., offer a clean and sustainable strategy for utilizing energy. As the core components, the electrode materials, including anodes, cathodes, and catalysts, play a direct decisive role in the device's performance in practical application. Therefore, the development of high-performance and low-cost electrode materials is critical for the success of these …

Xps Study Of Calcium Lanthanum Sulfide Ceramics, Brian E. Butkus

Graduate Thesis and Dissertation 2023-2024

Long wave infrared (LWIR) optics that transmit in the 8 to 14 m wavelength range and, additionally, can withstand severe physical and thermal stresses are needed for advanced remote sensing, guidance and communication-based applications. However, most non-oxide transparent LWIR optics do not have the wider transmission range, nor the hardness and resistance to thermal shock needed for extreme environments. Because of these limitations, research is circling back to a promising material, calcium lanthanum sulfide (CLS), that could meet LWIR needs for extreme environments.

In this thesis, we will demonstrate the abilities of x-ray photoelectron spectroscopy (XPS) as a technique for …

Functionalization Of 1d And 2d Nanostructures And Their Applications, Yuen Yee Li Sip

Graduate Thesis and Dissertation 2023-2024

Material discovery and development has been playing a significant role in shaping human civilizations, by studying and improving materials for appealing observations to aid in our survival as well as to satisfy our curiosity. From the common earthly materials that give us strong building structures and hunting weapons to the Silicon Age that contributes to the creation of modern electronics and computers, the development of novel and enhanced materials continues to grow. Recently, a new field has emerged that is rapidly expanding the engineering circle; these are called nanomaterials. By shrinking bulk materials into structures with nanoscale dimensions, there is …

Laser Powder Bed Fusion Of Bimetallic Structures, Asif Mahmud

Graduate Thesis and Dissertation 2023-2024

Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural development, and nanohardness variations. Constituent intermixing after LPBF was quantitatively estimated using thermo-kinetic coefficients of mass transport and compared with the diffusivity of Ni in the austenitic Fe-Ni system. The intermixing of primary solvents (Ni and Fe) in SS316L/IN718 bimetallic structures was observed for an intermixing zone of approximately 800 µm, and their intermixing coefficient was estimated …

A Thermal, Mechanical, And Materials Framework For A Shape Memory Alloy Heat Engine For Thermal Management And Energy Recovery, Maria Chikhareva

Electronic Theses and Dissertations, 2020-

Shape memory alloy (SMA) heat engines possess an inherent property of sensing a change in temperature, performing work, and rejecting heat through the shape memory effect resulting from a temperature-induced phase transformation. This work presents a framework for the design and implementation of an SMA-based Stirling heat engine for maximum power or speed incorporating and combining mechanical, thermal, and material aspects. The motivation for this work comes from the growing need for reliable thermal management and energy recovery in both ground and space applications of interest to NASA and commercial space companies. In future lunar and Mars missions, an SMA …

Development Of High Current Electromigration Test System For Evaluation Of Novel Solder Structures, Nicholas Pareis

Electronic Theses and Dissertations, 2020-

Electromigration reliability of ball-grid-array (BGA) solder joints is emerging as a critical area of research for advanced microelectronic devices, especially those with high power requirements. In this study, a novel high current electromigration test system, including a temperature sensing capability, was designed and developed for the purpose of performing electromigration characterization of various BGA solder joint structures, including features designed for reduced current crowding. This study consisted of two main parts: design and development of a novel high current electromigration test system, and using this novel system for electromigration characterization of BGA solder joints. In the first portion of this …

High Performance And Low Cost Passivating, Carrier-Selective Contacts For Silicon Photovoltaics, Jannatul Ferdous Mousumi

Electronic Theses and Dissertations, 2020-

The world is now focusing on expanding renewable energy sources to reduce the carbon footprint and mitigate climate change. Solar energy is one of the most environment-friendly and fastest-growing renewable energy sources in the present world. While crystalline silicon (c-Si) based devices dominate the global photovoltaics (PV) market with a current share of 95%, it is still challenging to achieve the theoretical efficiency limit of 29.4% with this technology due to a few performance limiting factors. Contact recombination losses are dominant among them which result from the recombination of photo-generated charge carriers due to the presence of defects at the …

Synchronous Raman Microspectroscopy And Laser Beam Induced Current Measurements As A Metrology Tool For Solar Cells And Optoelectronic Devices, Jeya Prakash Ganesan

Electronic Theses and Dissertations, 2020-

This works developed synchronous Raman microspectroscopy with laser beam induced current (LBIC) measurements to generate insights into structure-property correlations in finished solar cell modules. Raman spectroscopy is a powerful, non-destructive technique to examine phase and composition of materials where a laser beam excites characteristic vibrational modes of chemical bonds in a material. Conducting Raman spectroscopy under a microscope (i.e., Raman microspectroscopy) with confocal capabilities allows the chemical constituents to be mapped with high spatial resolution in the x, y and z directions. Simultaneously, the excitation laser from Raman can also generate photocarriers in a semiconductor. In a solar cell, these …

From Field To Failure: Detecting And Understanding Reliability Defects In Crystalline Silicon Photovoltaics, Dylan Colvin

Electronic Theses and Dissertations, 2020-

Severe pollution levels and the growing influence of climate change have shown that dirty energy sources need renewable and sustainable replacements. The field of photovoltaics (PV) has grown substantially over the years from a niche space solar market to a commodity in large part due to improvements in reliability. Reliability of all materials in a PV module must be considered. The industry has seen an explosion of innovation in cell interconnection technologies with significant market penetration in the past several years. These emerging, less mature technologies require more reliability information to guide improvements. Degradation studies of long-term outdoor exposure and …

Influence Of Growth Parameters On The Synthesis Of Mos2 Films, Victor Okonkwo

Honors Undergraduate Theses

Information processing is crucial in modern society, placing a great emphasis on the performance of optoelectronic devices to match ever increasing processing and memory needs. Within these devices, MoS₂ has demonstrated great potential as transistors due to its enhanced electrostatic control. As increased layer thickness of quality MoS₂ films have been shown to boost the performance of its transistors, growth parameters for the synthesis of ideally uniform and large area multilayered films via chemical vapor deposition were investigated. By increasing the flow pressure in the system and the growth time, increasing levels of thickness and nucleation density was …

Improving The Performance And Durability Of Metal Contacts In Crystalline Silicon Solar Cells Using Advanced Characterization, Nafis Iqbal

Electronic Theses and Dissertations, 2020-

Solar energy is one of the fastest growing forms of energy generation due to its low cost, lack of emissions, minimal maintenance, and excellent durability. However, like any other technology, it is also not free from defects and degradation, which limit its performance in the real world. Most of the degradation is related to metal contacts, which also happens to be one of the most expensive items in manufacturing, comprising almost half of the cost of converting a silicon wafer into a photovoltaic (PV) cell. Therefore, studying contact degradation to make them reliable and free of defects is the key …

Engineering The Electrode Properties For Developing High Performance Supercapacitors, Kowsik Sambath Kumar

Electronic Theses and Dissertations, 2020-

Rising global warming concern demands the need for a rapid transition to renewable energy sources. The intermittent nature of these sources emphasizes the requirement of developing highly efficient electrochemical energy storage devices like supercapacitors and batteries. Supercapacitors are at the forefront of powering various devices spanning from electric cars to aircraft. Here, we have engineered the electrode material properties for developing supercapacitors with high capacitance, energy density and cycle life. Among the electrode materials, we have focused on improving the energy storage performance of 2D materials like graphene oxide (GO) and tungsten disulfide (WS2), in addition to metal oxides such …

The Effect Of Heat Transfer On Microstructural Development For Inconel718 Nickel-Based Superalloy In Laser Powder Bed Fusion, Erica Drobner

Electronic Theses and Dissertations, 2020-

Inconel 718 (IN718) is a superalloy with excellent corrosion resistance and high temperature stability, giving rise to its popular use in the aerospace industry as well as other high performing applications. This study utilizes the relatively low conductivity of IN718 to focus in on the heat transfer procedures in which occur during the laser powder bed fusion (LPBF) manufacturing process of metals. Cylindrical samples of constant geometry with varying dimensions of thermal supports were fabricated using a compatible IN718 build plate. As thermal support size increased, heat dissipation to the build plate consequently increased. Theoretically, this modification of heat transfer …

In Situ Transmission Electron Microscopy And Ab Initio Study Of The Electrochemomechanical Effect Of Lithium Penetration In Electrolytes For All-Solid-State Batteries, Megan Diaz

Electronic Theses and Dissertations, 2020-

Although the past twenty years have seen dramatic advancement in lithium-ion batteries (LIBs), these batteries are nearing their theoretical limit. Next generation energy storage technologies must therefore be developed to meet the ever-increasing demands for batteries with higher capacity, longer cycle lifetime, and increased safety. All-solid-state lithium battery (ASSLIB) technology is one of the promising candidates. It is equipped with a solid-state electrolyte (SSE) replacing the flammable organic liquid electrolyte used in current LIBs. The SSE's high modulus is expected to prevent lithium dendrites and enables the use of a lithium metal anode to contribute to its high capacity without …

Designing Physical And Chemical Confinement In Lithium Sulfur Battery Cathode For Suppression Of Shuttle Effect, Saisaban Fahad

Electronic Theses and Dissertations, 2020-

Lithium sulfur batteries (LSBs) are attracting attention as a next generation energy storage device because of their high energy density (2670WhKg-1), high specific capacity (1675 mAhg-1), low cost and environmental friendliness. However, there are several challenges that need to be overcome before LSBs can be implemented in general applications. This is due to the low electric conductivities of sulfur and lithium sulfide and large volume changes during charge/discharge cycling. Also, most importantly, the dissolution of lithium polysulfides into the electrolyte during cycling leads to capacity decay and low coulombic efficiency. Additionally, these lithium polysulfides can diffuse to the lithium anode …

Davydov-Split Aggregates Of Cyanine Dyes For Bovine Serum Albumin Detection, Yiping Ma

Electronic Theses and Dissertations, 2020-

The p-conjugated supramolecular aggregates have gained significant interest in recent years. The cyanine dye aggregates are particularly interesting due to their unique optical and excitonic properties, which cannot be found in individual molecules. Cyanine dyes can form different kinds of aggregates. H-aggregates are formed when dye molecules are packed in a face-to-face fashion, which gives rise to a blue-shift absorption band and strong emission quenching compared to the monomer. J-aggregates are composed of individual dye molecules in a head-to-tail stacking, which leads to a red-shift absorption band and a sharp intense emission band with a small Stoke shift compared with …

Processing-Microstructure-Property Correlation For 316l Stainless Steel Manufactured By Laser Powder Bed Fusion, Nathalia Diaz Vallejo

Electronic Theses and Dissertations, 2020-

The microstructural development of 316L stainless steel (316L SS) was investigated over a wide range of systematically varied laser powder bed fusion (LPBF) parameters, such as laser power, laser scan speed, hatch distance, and volumetric energy density. The use of volumetric energy density between 46 and 127 J/mm3 produced samples with relative density above 99.8% demonstrating that even in the optimized range of processing parameters the pores are unavoidable. Shifting from this range through a variation of laser scan speed produced two types of flaws, lack of fusion (LoF) and keyhole (KH) porosity leading to a decrease in the relative …

Designing The Electrochemical Interface To Enable Lithium Metal Batteries, Supriya Koul

Electronic Theses and Dissertations, 2020-

Although Li-ion battery is one of the most widely used energy storage devices, there have been extensive efforts to push its limit to meet the ever-increasing demands to improve its energy density for applications such as electric vehicles, portable electronics, and grid storages. Here, Li metal anode plays a key role in the next generation energy storage devices, ultimately enabling the anode-free configuration. However, there are major challenges that need to be overcome for a successful deployment of anode-free batteries. These include designing a competitive SEI, low Coulombic efficiency, and the formation of dendrites. To realize an effective anode-free configuration …

Structural Dynamics And Encapsulation Properties Of Polyelectrolyte Complex Micelles, Sachit Shah

Electronic Theses and Dissertations, 2020-

Charged therapeutics such as nucleic acids and proteins can treat a vast range of human diseases that are traditionally undruggable. Their broadness in treating disease is due to their ability to influence cellular function. However, their high charge density and physiological barriers such as enzymatic degradation, hinder the deliverability of these molecules to the sites of disease. Polyelectrolyte complex (PEC) micelles are core-corona nanostructures that can encapsulate charged molecules and offer a platform for delivery. PECs form the core, when two oppositely charged polyelectrolytes are mixed in an aqueous solution, and the micelle corona is a neutral hydrophilic polymer that …

Using Peptide Design To Engineer Polyelectrolyte Complex Biomaterials, Sara Tabandeh

Electronic Theses and Dissertations, 2020-

The self-assembly of oppositely charged polymers provides a versatile platform to design materials for diverse applications in biology and medicine. Electrostatically-driven phase separation of oppositely charged polymers in aqueous solution gives rise to the formation of a polymer-rich phase called a polyelectrolyte complex (PEC). PECs can be in the form of liquid droplets (complex coacervates) or amorphous solid precipitates. Unlike synthetic polymers, peptides are good candidates for developing tailor-made formulations and structure-property relationships due to their biocompatibility, precise control over sequences, and ability to program hydrogen bonding interactions. However, little is known about the effect of combining additional molecular interactions …

Surface Engineering Of Cerium Oxide Nanocyrstal Dispersions: Colloidal Properties, Ageing Effects, & Electroanalysis, Craig Neal

Electronic Theses and Dissertations, 2020-

Colloidal materials are highly diverse and present complex physicochemical properties which define their utilities in applications spanning diverse industries. In particular, nano-scale colloids have received tremendous attention due to their unique, specific activities as compared to larger-sized preparations. Within the biomedical sciences, nano-colloids are routinely used as inert carriers of therapeutics and/or diagnostic agents. Beyond this, researchers have developed functional colloids which demonstrate bio-active or diagnostic properties themselves: often related to an optimized, or tuned, surface character. Among these, nanoscale cerium oxide (nanoceria) has shown great promise as a bi-functional, therapeutic material: producing pro- or anti- oxidative chemical response in …

Processing Of 3d Porous Biomaterial Scaffolds To Enhance The In Vitro Breast Cancer Tumor Microenvironment, Zi Wang

Electronic Theses and Dissertations, 2020-

Tumors contain heterogeneous cell populations within the tumor microenvironment (TME). TME supports tumor progression and development via the function of multiple cell types and cell-extracellular matrix (ECM) interactions. 3D porous biomaterial scaffolds can be a type of in vitro tumor models to mimic TME ECM. Current tumor models lack structural complexity replicating tumor ECM, tunable mechanical properties, and have limited mass exchange between cells and their microenvironment. In this work, we firstly developed scaffolds with a hierarchical pore structure via the Freeze-FRESH(FF) fabrication technique that combines 3D printing and freeze-casting. Later, we studied the effect of varying processing parameters and …

Actin Cytoskeleton Dynamics And Organization Modulated By Macromolecular Crowding, Cation Interaction, And Nanomaterials, Jinho Park

Electronic Theses and Dissertations, 2020-

The assembly of actin, the essential cytoskeleton protein, into filaments and bundles/networks is important in various cellular processes including cell movement and morphogenesis. Actin bundle formation occurs in crowded intracellular environments with the aid of actin-crosslinking proteins. The role of actin-crosslinking proteins such as fascin and a-actinin in bundle formation has been investigated, however, how intracellular environments affect actin crosslinker-induced bundle formation is unknown. In the first two parts of this dissertation, we explore the effects of macromolecular crowding and cation interactions on the organization and mechanics of actin crosslinker-induced bundles. To determine how changing environmental conditions modulate actin bundling, …

Uv-Ozone Oxide Treatments For High-Efficiency Silicon Photovoltaic Devices, Munan Gao

Electronic Theses and Dissertations, 2020-

Fabrication of solar cells with higher efficiency, simpler processes and lower cost is largely perceived as the ultimate goal for photovoltaic research. To reach such a goal each step needs to be refined and optimized. In this dissertation, a UV-ozone treatment is proposed as a simple and versatile process that can be applied to multiple fabrication steps for improvement. The UV-ozone cleaning method provides comparable surface cleaning quality to more expensive and hazardous industrial standard RCA clean with less chemical used. A good passivation quality was achieved on both n-type and p-type silicon wafer by a silicon oxide/aluminum oxide passivation …

Microstructural Development Of Inconel 625 Nickel-Based Superalloy As Function Of Laser Powder Bed Fusion Parameters, Sofia Nucci

Electronic Theses and Dissertations, 2020-

Additive manufacturing (AM) allows fabrication of complex components with features that are impractical or impossible to achieve through conventional methods. Selective laser melting (SLM) powder bed fusion AM technology was selected for this study on Inconel 625, a widely utilized high-temperature alloy that is hard to machine. The present work investigates impact of laser power and scanning speed variations on the resulting characteristics of fabricated IN625 samples. Gas atomized metallic alloy powders were acquired and analyzed through laser diffraction to verify acceptable size distribution. Cubic samples were built with a range of laser scan speeds in 200 mm/s intervals for …

Solidification Cracking In Binary Al-Cu Alloys Additively Manufactured Through Laser Powder Bed Fusion, Keegan Muller

Electronic Theses and Dissertations, 2020-

Laser Powder Bed Fusion (LPBF) is an additive manufacturing technique with growing relevance in industry. However, alloys with a high susceptibility to micro-cracking during solidification cannot be feasibly manufactured through LPBF, such as in selected high-strength Al-alloys. The cracking susceptibility (CS) of Al-alloys varies with composition, so modeling CS with respect to composition is crucial in designing compatible alloys for LPBF. In a theoretical modeling of solidification cracking based on the Scheil equation, the relative CS is taken as the maximum value of |dT/d(fs^1/2)| when solidification is near completion. However, experimental observations of the crack density in Al-alloys suggest that …

Atomic-Scale Simulation Of Dissipation And Adhesion During Interactions Between Mineral Surfaces, Baochi Doan

Electronic Theses and Dissertations, 2020-

Adhesion and dissipation during surface interactions are important phenomena with wide applications in materials science, including cold-spray technology for additive manufacturing and stiction in MEMS (Mircro ElectroMechanical Systems). In planet formation theories, energy dissipation in collisions between mineral grains is important to the formation of dust-grain aggregates and planetesimals. Early contact mechanics theories such as Hertz and Johnson-Kendall-Roberts have laid theoretical foundations for understanding these phenomena. Recently, there are breakthroughs in using non-equilibrium thermodynamics methods to elucidate dissipation. For example, the Green-Kubo method can calculate transport coefficients based on the Fluctuation-Dissipation theorem, and Jarzynski equality can be used to determine …

Development Of Facile Microfabrication Technologies For The Fabrication And Characterization Of Multimodal Impedimetric, Plasmonic, And Electrophysiological Biosensors, Cacie Hart

Electronic Theses and Dissertations, 2020-

The objective of this dissertation was to develop novel methods of patterning inorganic and organic materials, develop biocompatibility evaluations, and subsequently apply these methods toward developing biosensors and lab-on-a-chip devices, such as Interdigitated Electrodes (IDEs) and Microelectrode Arrays (MEAs) on non-traditional (such as nanostructured and plasmonic) polymer substrates or deploy these methods to enhance precision cellular placement on traditional (glass) MEA substrates. It was hypothesized that a combination of such facile microfabrication techniques and patterning technologies on traditional and non-traditional substrates would increase the sensitivity and selectivity of such sensor platforms by several orders of magnitude, and potentially introduce new …

Mechanical Behavior Assessment Of Ti-6al-4v Alloy Produced By Laser Powder Bed Fusion, Asif Mahmud

Electronic Theses and Dissertations, 2020-

The present work correlates quasi-static, tensile mechanical properties of additively manufactured Ti-6Al-4V (Grade 23) alloy to the phase constituents, microstructure and fracture surface characteristics that changed with post-heat treatment of stress relief (670 °C for 5h) and hot isostatic pressing (HIP with 100MPa at 920 °C for 2h). Ti-6Al-4V alloy tensile specimens in both the horizontal (i.e., X and Y) and vertical (Z) directions were produced by laser powder bed fusion (LPBF) technique. Mechanical properties were determined using quasi-static, tensile testing for both the as-stress-relieved (ASR) and HIP specimens. For the ASR and HIP samples built in X, Y and …