Digital Commons Network^™

Spray-Dried Cellulose Nanofibril-Reinforced Polypropylene Composites For Extrusion-Based Additive Manufacturing, Lu Wang

Electronic Theses and Dissertations

Compared to conventional manufacturing process, additive manufacturing (AM) offers free-form design, lighter and more ergonomic products, short lead time and less waste. Extrusion-based AM can be used to print thermoplastics. However, extrusion-based AM has processing challenges in printing semi-crystalline thermoplastics, for instance, polypropylene (PP). Cellulose nanofibrils (CNF) are one type of cellulose nanofibers that are produced from pulp fibers. CNF has extraordinary properties which make it an ideal candidate to reinforce polymers. Spray-dried CNF (SDCNF) is able to be incorporated into thermoplastic matrices without modifying conventional processing procedures.

The mechanical properties of 3D printed plastic parts have been considered significantly …

Maine Literature 101: A Course For High School Seniors, Courtney Hawkes

Electronic Theses and Dissertations

In various schools across the state of Maine are teachers devoting their classroom time to exploring the rich history of Maine. At the high school level, many schools now offer at least an elective course in “Maine Studies” and Maine state standards require that local history is covered to a certain extent in high school history. Missing from these courses, however, is a study of Maine’s literature. Literature puts a realistic face to the events of history in a way that helps students see through the eyes of the people from that time period. Literature reveals internal emotions and conflicts …

Evaluating Potential For Water Quality Decline In Maine Lakes, Kaci N. Fitzgibbon

Electronic Theses and Dissertations

Understanding lake vulnerability with respect to eutrophication and loss of water quality is important for sustainability of aquatic ecosystems. This project aims at identifying and quantifying the effects of relevant physiochemical, climate, and watershed characteristics on lake vulnerability in order to develop management decision tools for the Maine Department of Environmental Protection (MEDEP). In a changing chemical and physical environment, using independent variables from each of these categories and then relating them to the summer lake epilimnetic phosphorus (P) concentrations allows for development of models to inform stakeholders of lake vulnerability to eutrophication problems.

We studied 24 lakes covering a …

Long-Term Sustainability Of Northern Mixedwood Management: Spatial And Temporal Aspects Of Forest Productivity, Bethany L. Munoz

Electronic Theses and Dissertations

Natural disturbances of moderate severity are common in northern temperate forests in Maine, USA. Given estimated return intervals of 575-1000 years for severe windstorms and 385-1200 years for severe fire events, few opportunities arise to evaluate high severity disturbances in northern mixedwood or northern conifer forests. This research evaluated 50-year results of clearcutting with whole-tree harvesting (WTH), stem-only harvesting (SOH), and stem-only harvesting with prescribed burning (SOHB) on growing stock, composition, and relationships among foliar and soil nutrient concentrations. At the other end of the disturbance spectrum, this research also investigated 60-year results of single-tree selection with a 10-year cutting …

Prospective Associations Of Homocysteine, Executive Function, And Depressive Symptoms, Peter J. Dearborn

Electronic Theses and Dissertations

Associations of cardiovascular risk factors, cognitive performance, and depressive symptoms have been well established. However, the directionality of these associations as well as the specificity of these associations with respect to executive function are less clear. Additionally few studies have determined whether genetic risk factors, such as apolipoprotein-E4 (APOE-E4) genotype, and age moderate the associations of cardiovascular risk factors such as homocysteine with changes in depressive symptoms and how these associations may be mediated by cognitive performance. The primary aim of this study was to analyze the bidirectional associations of a full range of cognitive domains and symptoms of depression …

Dynamic Modeling And Extreme Tension Analysis Of Mooring System For A Floating Offshore Wind Turbine, Wei Ting Hsu

Electronic Theses and Dissertations

For offshore wind industry, exploiting the dynamic behaviors of mooring lines is of increasing importance in floating offshore wind turbine (FOWT) mooring system design. Currently, the design philosophy for structures and moorings is based on principles and practices adopted in offshore oil and gas, including mooring systems that are optimized for applications in deeper waters. However, the design of FOWT mooring systems is facing several challenges, including installation costs, the stability of light-weight minimalistic platforms, and shallow water depths (50-300m). The extreme tension in mooring lines of a light displacement platform in shallow water is dominated by snap loads. Hence …

Modeling Of A Head - Neck Assembly Drop Tower Impact Test Using Abaqus, Hussein Sharqi Owaid

Electronic Theses and Dissertations

There are numerous potential causes of traumatic brain injury (TBI) and concussions, including traffic accidents, contact during sports and falls. Protection from these injuries is paramount because of the problems that result from TBI, such as loss of thinking and memory capability. Head impact from falls, especially in elderly, can also result in severe to fatal injury and some effects of brain injury are often not visible. For these reasons and more a need exists for protective head gear that can keep persons safe during at risk physical activity and that can protect fall prone persons from accidental injuries. Part …

Integrated Control Of Colorado Potato Beetle And Potato Virus Y Using Mineral Oil, Andrew K. Galimberti

Electronic Theses and Dissertations

Colorado potato beetle (Leptinotarsa decemlineata) (CPB) and Potato Virus Y (PVY) are two of the most damaging pests attacking potato crops. CPB can cause significant defoliation to potato fields and is difficult to control using insecticides because its populations rapidly develop insecticide resistance. PVY, which is transmitted non-persistently by aphids, can result in yield loss and rejection of seed potato lots. Due to its rapid mode of transmission, insecticides are often ineffective at curtailing the spread of the virus. Thus, an integrated pest management (IPM) approach is essential for both CPB and PVY control.

Mineral oil is a …

Envisioning Recovery: A Social-Ecological Systems Analysis Of Maine’S Co-Managed Sea Urchin Fishery, Kimberly L. Ovitz

Electronic Theses and Dissertations

Maine’s sea urchin resource has provided a critical source of income and cultural value to resource harvesters across the state, yet in the absence of adequate governance mechanisms, the urchin resource quickly succumbed to overharvest and persisting stock decline. Following collapse, the urchin fishery transitioned to an advisory co-management system characterized by increased collaboration between urchin harvesters and resource managers. As collaborative dialogue and decision-making continue, fishery participants are collectively envisioning a more sustainable future for this important natural resource.

This master’s thesis explores Maine’s urchin fishery as a complex and coupled social-ecological system (SES) and documents harvester and scientist …

Production Of Bio-Oil With Different Oxygen Content And Characterization Of Catalytic Upgrading To Transportation Fuel, Mubarak Mohammed Khlewee

Electronic Theses and Dissertations

The world’s increasing population requires an increase in transportation fuel production. The lack of production of transportation fuels due to the shortage of fossil fuel resources combined with concerns about global emissions of carbon dioxide from fossil fuel combustion are the two major issues that have driven researchers to actively pursue alternative sources for oil production. Biomass is being considered as an alternative feedstock to produce fuel and chemicals due to its abundance and renewability. It has many features that make it suitable as a source of transportation fuel production. However, the bio-oil produced by the fast pyrolysis process has …

Cellulose Nanofiber-Reinforced Impact Modified Polypropylene: Assessing Material Properties From Fused Layer Modeling And Injection Molding Processing, Jordan Elliott Sanders

Electronic Theses and Dissertations

The purpose of this research was to investigate the use of cellulose nanofibers (CNF) compounded into an impact modified polypropylene (IMPP) matrix. A IMPP was used because it shrinks less than a PP homopolymer during FLM processing. An assessment of material properties from fused layer modeling (FLM), an additive manufacturing (AM) method, and injection molding (IM) was conducted. Results showed that material property measurements in neat PP were statistically similar between IM and FLM for density, strain at yield and flexural stiffness. Additionally, PP plus the coupling agent maleic anhydride (MA) showed statistically similar results in comparison of IM and …

Operational Limits Of Blade Coating With High Aspect Ratio Pigments, Lisa Weeks

Electronic Theses and Dissertations

During the blade coating of paper, operational issues such as stalagmite formation, scratches or spits can develop at high solids content and high web speeds. For coatings that contain high aspect ratio pigments, these difficulties appear at lower solids concentrations and slower machine speeds than with more spherical shaped pigments. These operational issues are important because plate shaped particles have good properties in publication and barrier grades. A number of possible mechanisms have been described in the literature, but a clear cause has not been established nor have methods to estimate the operational limits been proposed.

The influence of particle …

Transformation Of Nonlinear Waves In The Presence Of Wind, Current, And Vegetation, Haifei Chen

Electronic Theses and Dissertations

Accurate prediction of extreme wave events is crucial for the safe maritime activities and offshore operations. Improved knowledge of wave dissipation mechanisms due to breaking and vegetation leads to accurate wave forecast, protecting life and property along the coast. The scope of the thesis is to examine the wave transformations in the presence of wind, current, and vegetation, using a two-phase flow solver based on the open-source platform OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with a Volume of Fluid (VOF) surface capturing scheme and a turbulence closure model. This RANS-VOF model is adapted to develop a numerical wind-wave-current …

Water Chemistry Dynamics In Four Vernal Pools In Maine, Usa, Lydia H. Kifner

Electronic Theses and Dissertations

Vernal pools are small seasonal wetlands that are a common landscape feature that contribute to biodiversity in northeastern North American forests. However, even basic information about their biogeochemical functions, such as carbon cycling, is limited. Dissolved gas concentrations (CH₄, CO₂) and other water chemistry parameters were monitored weekly at the bottom and surface of four vernal pools in central and eastern Maine, USA, from April to August 2016. The vernal pools were supersaturated with respect to CH₄ and CO₂ at all sampling dates and locations. Concentrations of dissolved CH₄ and CO₂ ranged …

Developing A Collaborative Research Program To Evaluate Fine-Scale Groundfish Dynamics In Eastern Maine, Mattie Rodrigue

Electronic Theses and Dissertations

Fisheries science conducted and used for management strategies in the Gulf of Maine (GOM) is conducted at broad spatial and temporal scales. There is a tendency for fisheries-independent monitoring programs, which play a critical role in fisheries assessment and management, to miss fine-scale dynamics, especially given the complex hydrographic structures characterizing the GOM. In New England, fishermen participating in a heterogeneous groundfish fishery within the GOM may have varied perceptions of fish abundance or distribution depending on the scale at which they participate in the fishery. Overlooking fine-scale life-history dynamics coupled with scale-mismatch in science and management may perpetuate a …

Risk Perceptions Of Metallic Mineral Mining In Maine, Andrew Morgan

Electronic Theses and Dissertations

As society’s need for metals increases more mining locations will likely be sought. Maine contains 10 known significant metal deposits but there are currently no active metal mines. Interest in developing one of these deposits prompted legislative changes to the metallic mineral mining (MMM) law and rules to be pursued. Social license to operate (SLO) or the acceptance of mining activities by communities plays an increasing role in the siting and profitability of mining activities. This study broadens the application of SLO to the context of a statewide policy debate. Appropriate policy development for MMM needs to consider the views …

How Do We Collaborate? A Look Into Maine's Sustainable Ecological Aquaculture Network, Abby Jane Roche

Electronic Theses and Dissertations

As a society we realize that the dynamic needs of science and society are often complex and interdependent and that there is a need to work with and across diverse expertise and practices in order to create the development of new methods and to provide innovative solutions to socially relevant work. Thus, we call collaborative research efforts into action. Maine’s Sustainable Ecological Aquaculture Network (SEANET) is such an endeavor, as it is a collaborative effort traversing a nexus of complex, dynamic challenges in Maine, including issues related to socio-economic shifts, climate change, and declining capture fisheries. While SEANET’s plan to …

Integrated Environment And Proximity Sensing For Uav Applications, Shawn S. Brackett

Electronic Theses and Dissertations

As Unmanned Aerial Vehicle (UAV), or “drone” applications expand, new methods for sensing, navigating and avoiding obstacles need to be developed. The project applies an Extended Kalman Filter (EKF) to a simulated quadcopter vehicle though Matlab in order to estimate not only the vehicle state but the world state around the vehicle. The EKF integrates multiple sensor readings from range sensors, IMU sensors, and radiation sensors and combines this information to optimize state estimates. The result is an estimated world map to be used in vehicle navigation and obstacle avoidance.

The simulation handles the physics behind the vehicle flight. As …

American Woodcock Migration Ecology At An Important Stopover, Cape May, New Jersey, Brian B. Allen

Electronic Theses and Dissertations

Migration poses risks and energetic demands to individuals that may be greater than those experienced during non-migratory periods. Most migratory birds require stopover sites to rest and recuperate energy spent during migratory flights, and stopover locations can alleviate risks and provide supplemental energy en route to the animal’s end destination. An individual’s stopover duration is contingent first on energy acquisition that is constrained by resource availability, and secondarily on environmental conditions such as weather that may facilitate or constrain continued migration. From 2010 to 2013 I conducted a radio-telemetry study of a short-distance migrant, the American Woodcock (Scolopax minor), on …

Improving Management And Conservation Of Cusk (Brosme Brosme): Habitat Distribution, Bycatch Interactions, And Conservation Practices, Jocelyn M. Runnebaum

Electronic Theses and Dissertations

Cusk (Brosme brosme) are a National Oceanic and Atmospheric Administration species of concern, currently under internal status review for the Endangered Species Act, but are considered data limited. Current concerns for cusk include: decline in abundance, increase in fishing mortality relative to survey biomass, increased patchiness in habitat, and lack of management (72 FR 10710). Future management will require an improved understanding of cusk distribution, habitat use, spatial distribution of bycatch interactions, and the impact of bycatch on the population. This study set out to evaluate changes in cusk distribution and habitat, locations and levels of bycatch, and …

Exploring The Ways In Which Highly Efficacious Intermediate Teachers Employ Best Practices In Reading Instruction For Struggling Readers, Terrence P. Young

Electronic Theses and Dissertations

The purpose of this mixed method study was to build on the earlier efficacy work of Tschannen, Moran, and Hoy (2001) and the reading teacher efficacy work of Szabo and Mokhtari (2004) to add to educational research related to teacher efficacy and reading. This study is specifically focused on the teaching of reading to struggling readers at the intermediate levels. The study was guided by four research questions that focused on the teaching of struggling readers at the intermediate level. Reading teacher self-efficacy levels were established through a survey instrument. In addition, data from two interviews, structured and semi-structured, about …

Using Hydroacoustics To Investigate Biological Responses In Fish Abundance To Restoration Efforts In The Penobscot River, Maine, Constantin C. Scherelis

Electronic Theses and Dissertations

Spatiotemporal advantages linked to hydroacoustic sampling techniques have caused a surge in the use of these techniques for fisheries monitoring studies applied over long periods of time in marine systems. Dynamic physical conditions such as tidal height, boat traffic, floating debris, and suspended particle concentrations result in unwanted noise signatures that vary in intensity and location within a hydroacoustic beam over time and can be mixed with the acoustic returns from intended targets (e.g., fish). Typical processing filters applied over long term datasets to minimize noise and maximize signals do not address spatiotemporal fluctuations of noise in dynamic systems. We …

Creating Renewable Tunable Polymers From Hydroxymethylfurfural, Meredith C. Allen

Electronic Theses and Dissertations

The research here deals with the conversion of 5-hydroxymethylfurfural (HMF) into a tunable polymer. HMF is a known derivative that can be acquired from biomass via hydrolysis of cellulose followed by isomerization and finally selective dehydration. The process considered here is being developed to create tunable polymers from HMF and involves several different steps, three of which are covered here. The first step, an etherification, is the reaction of HMF with an alcohol. This step is significant because in this step the R-group from the alcohol is added to HMF and the branching portion formed is carried over to the …

The Paradigm Of Engagement: Integrating Social Science And Extension Outreach To Engage Beginning Family Forest Owners, Ian Anderson

Electronic Theses and Dissertations

Family forest owners own 36% of the forestland in the United States. These lands provide ecosystem services and natural resources to a broad community and management of these lands should be based on informed decisions. However, many family forest owners are unaware of conservation and stewardship options, and the number of unaware landowners may be increasing. A new cohort of beginning family forest owners (BFFO), who have acquired land in the past 5 years, has emerged. Programs designed to inform landowners about different management opportunities tend to attract only a small group of interested owners. In the following 2 phase …

Characterization Of Catalysts For Hydrodeoxygenation Of Bio-Oils Using Phenol As A Model Compound, Abdulazeez Mohammed Khlewee

Electronic Theses and Dissertations

Due to the environmental considerations, depletion of fossil fuel reserves and fluctuating non-renewable fuel price, converting non-edible lignocellulosic biomass into renewable energy resources has gained significant importance. Phenol has been chosen as a model compound for catalytic screening because it is abundant in bio-oil composition and shows a high resistance to oxygen removal during hydrodeoxygenation (HDO) reactions. HDO of phenol produces chemicals that can be used as transportation fuels (Aromatics) or fuel additives. Theoretically, HDO of phenol has two distinct reduction pathways: direct deoxygenation (DDO) and hydrogenation (HYD). The previous results published by our group showed a precedent activity and …

Evaluating The Influence Of Stem Form And Vigor On Product Potential, Growth, And Survival For Northern Commercial Hardwood Species, Mark Castle

Electronic Theses and Dissertations

Northern hardwood and mixed-wood forest types occupy a considerable percentage of the forest landscape across the Northeastern United States and portions of eastern Canada. While capable of producing valuable saw timber and veneer products, hardwood species demonstrate a wide range of stem quality resulting from the large variety of stem forms and defects that these species can manifest. The effect of different stem forms and damage has largely not been accounted for in predictions of volume, growth, and mortality. In addition to potential bias in growth and yield applications, the lack of quantification of these features has left the …

Prospective Studies Of Cardiovascular Risk Factors And Mild Cognitive Impairment, Kevin Sullivan

Electronic Theses and Dissertations

The association of cardiovascular risk factors including hypertension, diabetes, cholesterol, kidney function, and arterial stiffness with cognitive impairment in older adults is a well-studied phenomenon. However, there is considerably less evidence relating cardiovascular health specifically to a diagnosis of Mild Cognitive Impairment (MCI). As a precursor state of dementia, MCI is characterized by a decline in cognitive function from previous level, but not to the degree that activities of daily living are impaired. Not everyone who is diagnosed with MCI will eventually transition to dementia, but the transition rates are much higher compared to the general population (5-15% per year …

Renewable Hydrogels From Norbornene-Functionalized Carboxymethyl Cellulose And A Short Dithiol Crosslinked Via A Thiol-Ene Reaction, Thomas Mcoscar

Electronic Theses and Dissertations

Cellulose-based hydrogels - three dimensional "solid" structures composed primarily of liquid water and held together by an interconnected polymer network - were created by first functionalizing carboxymethyl cellulose (CMC), a cellulose derivative, with carbic anhydride in a basic aqueous reaction with the intent of developing novel hydrogels from renewable materials. The product of this reaction, carbic CMC (cCMC), had a new norbornene group as a subsection of the carbic group. Norbornene is a reactive alkene structure that allows for further chemistry with cCMC, such as crosslinking. cCMC was crosslinked with 2,2'-(ethylenedioxy)diethathiol to create hydrogels using a water-soluble, UV-sensitive radical initiator …

Oyster Aquaculture Site Selection Using Landsat 8-Derived Sea Surface Temperature, Turbidity, And Chlorophyll A., Jordan Snyder

Electronic Theses and Dissertations

Remote sensing data is useful for selection of aquaculture sites because it can provide water-quality products mapped with no cost to users. However, the spatial resolution of most ocean color satellites is too coarse to provide usable data within many estuaries. The more recently launched Landsat 8 satellite has both the spatial resolution and the necessary signal to noise ratio to provide temperature, as well as ocean color derived products along complex coastlines. The state of Maine (USA) has an abundance of estuarine indentations (~3,500 miles of tidal shoreline within 220 miles of coast), and an expanding aquaculture industry, which …

So2-Alcohol-Water Fractionation Of Sugarcane Straw, Asif Sharazi

Electronic Theses and Dissertations

Climate change resulting from fossil fuels combustion is motivating researchers to explore feasible routes to convert renewable biomass into biofuels and biochemicals for a sustainable society. Typically, biofuel is produced from corn or sugarcane but both feedstocks compete with human food supply. Thus, lignocellulosics as renewable feedstock represent a more ethical and ecofriendly approach. Sugarcane straw (SCS) is a cheap and abundantly available feedstock which potentially can be used for biofuels/biochemicals production. It can also help to mitigate environmental and health problems resulting from conventional practice of SCS burning in the fields.

There are different biomass conversion technologies for production …