Physical Sciences and Mathematics Commons^™

Advances In Cellulose Nanomaterial-Based Foams For Environmental Applications, Md Musfiqur Rahman

Electronic Theses and Dissertations

The use of metal-oxide nanoparticles adsorbents is limited to fixed-bed columns in industrial-scale water treatment applications. This limitation is commonly attributed to the tendency of nanoparticles to aggregate, the use of non-sustainable and inefficient polymeric resins as supporting materials, or a lack of adsorption capacity. Foams and aerogels derived from cellulose nanomaterials have unique characteristics, such as high porosity and low density, which enables their use in a variety of environmental applications, including water treatment. However, the overall use of cellulose nanomaterial-based foams in various environmental sectors is limited due to the high cost of production associated with time- and …

A Map-Algebra-Inspired Approach For Interacting With Wireless Sensor Networks, Cyber-Physical Systems Or Internet Of Things, David Almeida

Electronic Theses and Dissertations

The typical approach for consuming data from wireless sensor networks (WSN) and Internet of Things (IoT) has been to send data back to central servers for processing and analysis. This thesis develops an alternative strategy for processing and acting on data directly in the environment referred to as Active embedded Map Algebra (AeMA). Active refers to the near real time production of data, and embedded refers to the architecture of distributed embedded sensor nodes. Network macroprogramming, a style of programming adopted for wireless sensor networks and IoT, addresses the challenges of coordinating the behavior of multiple connected devices through a …

Accessible Autonomy: Exploring Inclusive Autonomous Vehicle Design And Interaction For People Who Are Blind And Visually Impaired, Paul D. S. Fink

Electronic Theses and Dissertations

Autonomous vehicles are poised to revolutionize independent travel for millions of people experiencing transportation-limiting visual impairments worldwide. However, the current trajectory of automotive technology is rife with roadblocks to accessible interaction and inclusion for this demographic. Inaccessible (visually dependent) interfaces and lack of information access throughout the trip are surmountable, yet nevertheless critical barriers to this potentially lifechanging technology. To address these challenges, the programmatic dissertation research presented here includes ten studies, three published papers, and three submitted papers in high impact outlets that together address accessibility across the complete trip of transportation. The first paper began with a thorough …

Wave Attenuation Through Submerged Oyster Aquaculture Cages, Liam T. Hanley

Electronic Theses and Dissertations

Coastal erosion presents a growing issue to shorelines around the world and is especially harmful to Maine, a region where sea-level rise is higher than the global average. Green and hybrid coastal defense strategies are being implemented around the country to provide sustainable, habitat-friendly solutions to erosion control. Maine is a hotspot for commercial aquaculture, with an estimated $13.6 million economic impact. This study looks to bridge the gap between Maine aquaculture and the living shorelines initiative, by determining the wave attenuating properties of submerged oyster cages. The project will be able to inform local oyster farmers, resource planners, and …

Longitudinal Case-Control Study Of Mammographic Breast Tissue Subtypes, Kendra Batchelder

Electronic Theses and Dissertations

Breast density is a known risk factor for breast cancer. However, there has been limited research on potential subtypes of mammographic dense breast tissue to identify areas of active dense tissue that is structurally reorganizing and links to cancer dynamics, versus areas of passive dense tissue which remains organized. We hypothesize that the amounts of subtypes of mammographic dense tissue and the associated rate of change through time could provide insights into breast cancer risk. A retrospective study was conducted to investigate breast cancer using longitudinal screening mammograms and accompanying pathology reports collected in 2015. Patients were matched by age …

Nanocellulose Based Foams For Low-Cost Disposable Medical Applications, Dominic Kugell

Electronic Theses and Dissertations

Polyurethane foams have been a staple material for their use in medical positioners, such as post-surgery elevation pillows as well as specific tailored positioners for their use during surgery. Polyurethane foams are preferred because of their lower cost compared to other petroleum derived foams, their versatility, and suitable mechanical properties. However, the environmental impact, including both cost and perception, of these foams is immense. Therefore, alternatives are being explored with biopolymers emerging as a promising class of materials. Cellulose is one such polymer that has recently demonstrated desirable properties. In this study, cellulose nanofibrils (CNF), a household foaming agent, and …

Synthesis Of A Pharmaceutical Precursor From Bioderived Glucose, Justin O. P. Waters

Electronic Theses and Dissertations

Medication costs in the U.S. are high, and manufacturing and production comprise the largest share of those costs. As the world continues to shift to more sustainable methods of production, there are opportunities to reduce these costs through green synthesis. A large number of pharmaceuticals are derived from a precursor (S-3-hydroxy-gamma-butyrolactone ‘HBL’). Drugs that treat cancer, antivirals, antibacterial drugs, and some cholesterol medications all can be derived from HBL. Currently, HBL is almost exclusively derived from petroleum through an expensive and resource intensive process. Until recently, ‘green’ efforts to derive HBL from biomass have been plagued with many of the …

Development And Applications Of Similarity Measures For Spatial-Temporal Event And Setting Sequences, Fuyu Xu

Electronic Theses and Dissertations

Similarity or distance measures between data objects are applied frequently in many fields or domains such as geography, environmental science, biology, economics, computer science, linguistics, logic, business analytics, and statistics, among others. One area where similarity measures are particularly important is in the analysis of spatiotemporal event sequences and associated environs or settings. This dissertation focuses on developing a framework of modeling, representation, and new similarity measure construction for sequences of spatiotemporal events and corresponding settings, which can be applied to different event data types and used in different areas of data science. The first core part of this dissertation …

Effects Of Fibril Morphology And Interfacial Interactions On The Behavior Of Polymer-Grafted Cellulose Nanofibril Reinforced Thermoplastic Composites, Peter V. Kelly

Electronic Theses and Dissertations

Mechanically refined cellulose nanofibrils (CNFs) promise to be a high-volume, sustainable, nanoscale reinforcement for thermoplastic composites. They are currently held back by poor interfacial interactions with composite matrices, energy intensive drying, and drying induced fibril aggregation. In this dissertation, we explored how a grafting-through polymerization scheme modified the surface of CNFs with a wide variety of commodity polymers and overcame many of these technical challenges.

The first phase of the research was concerned with characterizing the unique morphology of these CNFs as a function of refinement energy. This characterization was employed to understand how the materials’ morphologies affected their interfacial …

Hybrid Power Spectral And Wavelet Image Roughness Analysis, Basel White

Electronic Theses and Dissertations

The Two-Dimensional Wavelet Transform Modulus Maxima (2D WTMM) sliding window methodology has proven to be a robust approach, in particular for the extraction of the Hurst (H) roughness exponent from grayscale mammograms. The power spectrum is a computational analysis based on the Fourier transform that can be used to estimate the roughness of a scale-invariant image or region via the calculation of H. We aim to examine how the calculation of H in fractional Brownian motion (fBm) images and mammograms can be improved. fBm images are generated for H ∈ [0.00,1.00] for testing through the previous 2D …

Influence Of Platinum Nanoparticles On Ionic Transport And Hydrogen Reactivity Of Yttria-Stabilized Zirconia Thin Films, Firas Mahyob

Electronic Theses and Dissertations

Yttria-stabilized zirconia (YSZ) is a widely used ceramic material in solid oxide fuel cells, oxygen sensors, and sensing applications due to its high ionic conductivity, chemical inertness, and thermal stability. YSZ is promising active coating for use in miniaturized harsh environment wireless surface acoustic sensors to monitor gases such as H₂. Adding catalytic Pt nanoparticles can enhance gas reactivity and lead to associated film conductivity changes.

In this work, thin films with an (8% Y₂O₃ - 92% ZrO₂) composition were deposited onto piezoelectric langasite substrates using RF magnetron sputtering in Ar:O₂ - …

Thermal Stability Of Platinum-Silicon Alloy Films Grown On Langasite Substrates For Use In Microwave Acoustic Sensor Technology, Kell Fremouw

Honors College

Wireless sensors that can operate in temperatures up to 1000°C are widely needed for real time monitoring of large-scale industrial processes. Such sensors will improve efficiency and prevent component failure. Under previous work at UMaine, Surface Acoustic Wave Resonator (SAWR) sensors fabricated on piezoelectric langasite (La₃Ga₅SiO₁₄) wafers have shown promise for wireless strain measurements at high temperatures. However, there is a major technical challenge in attaching SAWR langasite based sensors to metal parts because the large differences in the coefficient of thermal expansion (CTE) between langasite and metals leads to large thermal stresses and …