Materials Science and Engineering Commons^™

Corn Stover Biochar In Gypsum Board: Empirical Analysis Of Thermal Conductivity And Flexural Strength, Albena Yordanova

Dissertations and Theses @ UNI

Gypsum board, an economical and durable finish material for wall and ceiling construction in the United States and worldwide, is the component with the lowest thermal performance in a typical exterior wall assembly. It also constitutes a substantial portion of construction waste in landfills, potentially creating harmful environmental effects and dangerous gases. To minimize the negative effects of fast growing construction waste of gypsum in landfills and meet higher standards for energy efficiency in construction, there is a need to explore sustainable ways of improving thermal properties of gypsum board and recycling the material. Gypsum can be recycled and used …

Investigation Of The Resistance To Demagnetization In Bulk Rare-Earth Magnets Comprised Of Crystallographically-Aligned, Single-Domain Crystallites With Modified Intergranular Phase, Jie Li

Dissertations, Master's Theses and Master's Reports

The research presented in this dissertation investigates whether an increased coercivity of Neodymium-Iron-Boron (Nd2Fe14B) based bulk magnets at elevated temperature (160°C), which is now only obtainable by substituting ~7wt% dysprosium (Dy) for a portion of neodymium (Nd), can be achieved through specific microstructural modifications with decreased Dy concentrations. The approach is to reduce the size of individual crystallographically-aligned grains in the magnet so that each grain can only support a single magnetic domain and to simultaneously dilute the Nd-Fe inter-granular phase present in conventional magnets with a non-Fe-containing, Nd-rich phase (Nd-Cu alloy) in an attempt to partially magnetically isolate the …

Inhibition Of Bacterial Growth And Prevention Of Bacterial Adhesion With Localized Nitric Oxide Delivery, Julia Osborne

Dissertations, Master's Theses and Master's Reports

Bacterial infections continue to be a problem at the site of an indwelling medical device, and over the years, various bacterial strains have become more resistant to current antibiotic treatments. Bacterial infection at an indwelling medical device can be dangerous and affect the performance of the medical device which can ultimately lead to the failure of the device due to bacterial resistance to treatment.

Nitric Oxide (NO) has been shown to possess antibacterial properties to prevent and inhibit bacterial growth. NO releasing coatings on indwelling medical devices could provide a reduction in bacterial infections that occur at the device site …

The Effect Of Solidification Rate And Solutionizing Quench Rate On The Mechanical Properties And Hardening Response Of Aluminum Alloys: A Quantitative Comparison, Rafael Gil-Figueroa

Dissertations, Master's Theses and Master's Reports

A comparative study of five aluminum alloys was performed to characterize the effect of solidification rate and quench rate on casting microstructure and properties. The alloys were cast in the geometry for Jominy End Quench (JEQ) testing, so as to take advantage of the JEQ test’s ability to give data on multiple quench rates in a single sample and illustrate the quench sensitivity of an alloy. While the Jominy End Quench test has been used in aluminum alloys, the effects of solidification rates have not been assessed in depth. The work done by other studies has either focused on a …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Microwave Material Characterization Of Alkali-Silica Reaction (Asr) Gel In Cementitious Materials, Ashkan Hashemi

Doctoral Dissertations

"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive …

Synthesis And Functionalization Of A Triaryldiamine-Base Photoconductive/Photorefractive Composite, And Its Application To Aberrated Image Restoration, Yichen Liang

Doctoral Dissertations

"Organic photorefractive (PR) composites have recently emerged as an important class of materials for applications including high-density data storage, optical communication, and biomedical imaging. In an effort to further improve their performance, this study focused on the utilization of functionalized semiconductor nanocrystals to photosensitize triaryamine (TPD)-based PR composites, as well as the application of TPD-based PR composites in the restoration of aberrated optical information. A novel approach to functionalize CdSe quantum dot (QCdSe) was firstly introduced where the sulfonated triarydiamine (STPD) was used as charge-transporting ligand to passivate QCdSe. TPD-based photoconductive and PR composites were photosensitized with the STPD-passivated QCdSe …

On The Spheroidal Graphite Growth And The Austenite Solidification In Ductile Irons, Jingjing Qing

Doctoral Dissertations

"Evolutions of austenite and nodular/spheroidal graphite particles during solidifications of ductile irons were experimentally investigated. Spheroidal graphite particle and austenite dendrite were found nucleated independently in liquid. Austenite dendrite engulfed the spheroidal graphite particles after contact and an austenite shell formed around a spheroidal graphite particle. The graphite diameter at which the austenite shell closed around nodule was determined. Statistically determined graphite size distributions indicated multiple graphite nucleation events during solidification.

Structures in a graphite nodule varied depending on the growth stages of the nodule in ductile iron. Curved graphene layers appearing as faceted growth ledges swept circumferentially around the …

Mdm2 Case Study: Computational Protocol Utilizing Protein Flexibility Improves Ligand Binding Mode Predictions, Anthony Thomas Ascone

Graduate Theses/Dissertations

Recovery of the P53 tumor suppressor pathway via small molecule inhibitors of onco-protein MDM2 highlights the critical role of computational methodologies in targeted cancer therapies. Molecular docking programs in particular, provide a quantitative ranking of predicted binding geometries based on binding free energy allowing for the screening of large chemical libraries in search of lead compounds for cancer therapeutics. This study found improved binding mode predictions of medicinal compounds to MDM2 using the popular docking programs AutoDock and AutoDock Vina, while adopting a rigid-ligand/flexible-receptor protocol. Crystal structures representing small molecule inhibitors bound to MDM2 were selected and a total of …

Comparative Characterization Of Molybdenum Oxide Thin Films Grown On Various Substrates Using Temporally Different Pulsed Laser Deposition Techniques, Krishna Harsha Puppala

Graduate Theses/Dissertations

Pulsed Laser Deposition (PLD) technique, with its vast tunability in terms of thin film fabrication has been the center of this study. By changing the temporal component of the laser source used for deposition into the femtosecond (fs) regime, interesting structural, morphological changes can be achieved which may prove to be beneficial for photocatalytic applications. In particular, molybdenum oxide thin films, which are the less well-studied and potentially newer candidates for photocatalysis applications have been chosen for investigation. Hence, a detailed characterization study of molybdenum oxide thin films synthesized using femtosecond-based (f-PLD) and nanosecond-based (n-PLD) techniques, was carried out in …

Real-Time Monitoring Of Personal Exposures To Carbon Dioxide, Elliott T. Gall, Toby Cheung, Irvan Luhung, Stefano Schiavon, William W. Nazaroff

Mechanical and Materials Engineering Faculty Publications and Presentations

Elevated indoor CO₂ levels are indicative of insufficient ventilation in occupied spaces and correlate with elevated concentrations of pollutants of indoor origin. Adverse health and well-being outcomes associated with elevated indoor CO₂ levels are based on CO₂ as a proxy, although some emerging evidence suggests CO₂ itself may impact human cognition. Using portable monitors, we conducted an exposure study with 16 subjects in Singapore to understand the levels, dynamics and influencing factors of personal exposure to CO₂. Participants carried a CO₂ monitor continuously for 7-day periods recording their exposure levels at 1-min intervals. …

Materials Characterization Of Deposits On Starboard (Inboard) Elevon Actuator Shaft Recovered From Space Shuttle Columbia, Mayra Contreras

Open Access Theses & Dissertations

With the new era of space exploration upon us and the Orion spacecraft currently being tested, which would replace the Space Shuttle as the orbiter that will transport humans into space once again, safety assurance is the main component for a successful mission. Aerospace materials have always played a big role when it comes to safety assurance. Having the knowledge of what materials are suitable to keep using when designing the future spacecraft that will take humans to Mars is fundamental in order to be confident that the vehicle and all that comprises it will function as envisioned. Expanding the …

A Cracking Methodology To Assess Fracture And Fatigue Properties Of Asphalt Concrete Mixtures Using Overlay Tester, Victor M. Garcia

Open Access Theses & Dissertations

Several highway agencies have either implemented or considered implementing performance tests to predict the cracking potential of asphalt concrete (AC) mixtures in the laboratory setting. One such test, the Overlay Tester (OT) test, measures the number of cycles to failure of the AC specimens by simulating the opening and closing of the cracks induced by daily temperature variations and high tensile strain generated by the traffic load. The variability of the OT test results is expressed as a major concern in reliably characterizing the cracking potential of the AC mixes.

The performance of the OT test, in general, and current …

Wettability Of Magnesium Based Alloys, Victor Manuel Ornelas

Open Access Theses & Dissertations

The premise of this project was to determine the wettability behavior of Mg-based alloys using three different liquids. Contact angle measurements were carried out along with utilizing the Zisman method for obtaining values for the critical surface tension. Adhesion energy values were also found through the use of the Young-Dupre equation. This project utilized the Mg-based alloy Mg-2Zn-2Gd with supplemented α-Minimum Essential Medium (MEM), Phosphate Buffer Saline solution (PBS), and distilled water. These three liquids are commonly used in cell cultivation and protein adsorption studies. Supplemented α-MEM consisted of α-MEM, fetal bovine serum, and penicillin-streptomycin. Mg-2Zn-2Gd was used because of …

Molecular Dynamics Proxy Applications For Optimizing Performance Of Simulations Under Extreme Conditions, Jayalath Abeywardhana Mudiyanselage Madawa Abeywardhana

Open Access Theses & Dissertations

Exascale performance of scientific application is a prominent goal for the scientific community and computer hardware vendors. As a result, several proxy applications for the widely used scientific codes have been developed with the purpose of testing performance, memory and power consumption issues associated with simulations at the exascale. Co-MD is a proxy application for classical Molecular Dynamics (MD) codes based on the (SPaSM) Los Alamos code.

This work comprises two different but related computational aspects: performance evaluation and optimization of Co-MD (Co-Design Molecular Dynamics) for different computer architectures/execution models, and direct application of SPaSM (Scalable Parallel Short-range Molecular Dynamics) …

Improving The Engineering Properties Of Pla For 3d Printing And Beyond, Carmen R. Rocha

Open Access Theses & Dissertations

Additive manufacturing (AM), now more commonly known as 3D printing, has been classified as efficient, fast, and practical in the prototyping sector of product development. In the work presented here, we will use one of the AM techniques known as Material extrusion 3D printing (ME3DP), which has all the advantages of AM. However, one of the biggest challenges facing ME3DP technologies is the limitation of the range of materials used by this technique. Acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) are currently the most common thermoplastics materials used in ME3DP because of their ability to melt and be reprocessed. …

Intrinsic And Metal-Doped Gallium Oxide Based High-Temperature Oxygen Sensors For Combustion Processes, Ernesto Javier Rubio

Open Access Theses & Dissertations

Currently, there is enormous interest in research, development and optimization of the combustion processes for energy harvesting. Recent statistical and economic analyses estimated that by improving the coal-based firing/combustion processes in the power plants, savings up to ~$450-500 million yearly can be achieved. Advanced sensors and controls capable of withstanding extreme environments such as high temperatures, highly corrosive atmospheres, and high pressures are critical to such efficiency enhancement and cost savings. For instance, optimization of the combustion processes in power generation systems can be achieved by sensing, monitoring and control of oxygen, which is a measure of the completeness of …

Microstructural Investigation Of Vintage Pipeline Steels Highly Susceptible To Stress Corrosion Cracking, Monica Adriana Torres

Open Access Theses & Dissertations

The use of pipelines for the transmission of gas offers not only efficiency, but a number of economic advantages. Nevertheless, pipelines are subject to aggressive operating conditions and environments which can lead to in-service degradation [1] and thus to failures. These failures can have catastrophic consequences, such as environmental damage and loss of life [2]. One of the most dangerous threats to pipeline integrity is stress corrosion cracking (SCC). Despite the substantial progress that has been achieved in the field, due to the complex nature of this phenomenon there is still not a complete understanding of this form of external …