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Biomaterials and Biosystems. doi: 10.1016/j.bbiosy.2024.100097
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
This thesis explores innovative approaches to enhancing the functionality and applications of DNA-based materials through the development of DNA bottlebrush polymers (BBPs), DNA-intercalating supramolecular hydrogels (DISHs), and psoralen-based 3D printing techniques. The first chapter presents the synthesis and characterization of linear and cyclic DNA BBPs using a grafting-to approach. Plasmid DNA (pDNA) is used as the polymeric backbone, grafted with polyethylene glycol (PEG) side chains of varying molecular weights (750 Da, 2000 Da, and 5000 Da) to improve stability and functionality. Achieving high graft densities, up to 24% for mPEG750-CEA, and purifying the PEG-DNA conjugates were significant challenges addressed through spin filtration and AFM imaging. The study demonstrates that DNA BBPs can be synthesized on a large scale and applied to larger plasmids such as pEYFP (5045 bp) to generate highly concentrated samples up to 30 mg/mL with enhanced viscoelastic properties. The second chapter introduces DNA-intercalating supramolecular hydrogels, focusing on the use of intercalators such as acridine, thiazole orange, psoralen, and phenanthridine to form cross-links with DNA. Polymeric supramolecular hydrogels (PSHs) exhibit properties like tunable viscoelasticity, self-healing, and stimuli responsiveness, making them suitable for applications in drug delivery, tissue-mimicking materials, and 3D printing. This study develops DNA intercalating supramolecular hydrogels (DISHs) using bifunctional polymeric cross-linked DNA dyes: acridine, psoralen, thiazole orange, and phenanthridine. Mixing genomic salmon milt DNA with these cross-linkers led to significant changes in viscosity and fluorescence, confirmed by UV-Vis measurements. Temperature-dependent mechanical testing showed that Pso-PEG and Phen-PEG increased in viscosity with temperature, while Thi-PEG and Acr-PEG remained stable. Frequency sweeps revealed that Thi-PEG and Phen-PEG had increased elasticity at high frequencies, while Acr-PEG showed enhanced elasticity across all frequencies as temperature increased. These DISHs demonstrate tunable thermal and viscoelastic properties, offering new possibilities for robust, temperature-invariant materials in various applications. The third chapter explores the use of psoralen-based 3D printing to create highly controlled DNA hydrogels. Psoralen, a DNA intercalator activated by UV light at 365 nm, is used to form cross-links in DNA hydrogels. UV activation resulted in a purely elastic material for both 2Pso-PEG and 4Pso-PEG and a significant increase in mechanical strength, with storage moduli rising to 1,000 and 9,000 Pa respectively. 3D printing trials using the BioAssemblyBot demonstrated the hydrogels' capability to make simple structures with fidelity. The printed hydrogels maintained their structural integrity and mechanical properties, underscoring their potential for applications in tissue engineering and drug delivery systems. Overall, this thesis advances the field of DNA-based materials by developing new methodologies for creating and utilizing DNA BBPs, DNA-intercalating hydrogels, and psoralen-based 3D printing techniques. These innovations pave the way for future research and applications in biotechnology, materials science, and medicine.
Angewandte Chemie. doi: 10.1002/anie.202411115
Journal of Manufacturing Science and Engineering. doi: 10.1115/1.4066123
Advanced Materials. doi: 10.1002/adma.202405490
Scientific Report. doi: 10.1038/s41598-024-65731-9
International Journal of Plasticity. doi: 10.1016/j.ijplas.2024.104044
43rd International Deep Drawing Research Group (IDDRG) Conference. doi: 10.1088/1757-899X/1307/1/012006
CIRP Annals. doi: 10.1016/j.cirp.2024.04.026
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Since the late 1980’s tissue engineering has become an important field in regenerative medicine. Tissue engineering aims to create scaffolds designed to mimic the extracellular matrix (ECM) of human tissue, which is a complex, heterogeneous system. While there are a variety of approaches for scaffold fabrication, it is difficult to mimic the heterogeneity of the natural ECM. NH BioMade proposed a tissue engineering scaffold design to address these limitations, where multi-lobed particles can be 3D-printed to form a scaffold, providing heterogeneity in pore size by the incorporation of different-sized multi-lobed particles. In order for particles to be 3D printed into a structure they need to be a stable dispersed latex while printing that can then be triggered to assemble once printed. This work focuses on investigating the use of light as a trigger to assemble nanoparticles for further applications in tissue engineering. Light is an attractive stimulus as it is noninvasive and has excellent spatial and temporal resolution.
Photochemical cycloadditions have been previously used to assemble nanoparticles through dimerization of photoresponsive moieties like cinnamyl and coumarin. These dimerization reactions rely on the absorption of light to create excited states, which can react with ground states to form dimers. While inter-particle dimerization has been previously achieved in literature through photochemical cycloadditions, the particles typically used are gold nanoparticles on the order of 5-50 nm. In this work we investigated the use of the [4+4] cycloadditions of anthracene to cause particle assembly via inter-particle dimerization to occur in polymer latexes, varying the amount of the anthracene, particle size, and the softness of the particle. When these approaches did not allow for inter-particle dimerization, we investigated the use of polymer tethers terminated in the photoresponsive moiety grafted to particles to provide a greater degree of freedom and to move the reactive group further out from the particle. These systems did not work, due to premature particle clustering due to interactions of the tethers.
An alternative approach to generating light-responsive systems is to use radical-mediated photochemistry. Exposure of a photoinitiator to UV light results in radicals, which can mediate thiol-disulfide exchanges. A significant difference is that this approach possesses a longer lifetime of the reactive species than in photochemical cycloadditions. We investigated the use of a dithiol linker in the presence of a photoinitiator to induce thiol-disulfide exchanges with disulfide-containing particles, exploring the importance of dithiol concentration and the number of tethering sites in favoring inter-particle exchange. Inter-particle disulfide exchange was observed at specific concentrations of each, resulting in a light-induced assembly of nanoparticles. Learnings from this approach can be used in the development of a biocompatible system for tissue engineering applications.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Environmental regulations on volatile organic compounds implemented in the European Union have highlighted the strengths of waterborne coatings and adhesives. Emulsion polymerization is a heterophase reaction in which an aqueous medium suspends polymer particles. Polymer colloids have diverse applications ranging from paper coatings, cosmetics, food additives, and pressure-sensitive adhesives, just to name a few. With such a wide range of applications, each latex requires a unique set of mechanical and chemical properties. One method used to control various mechanical properties is crosslinking, in which an insoluble “gel” is produced. Previous research by the Tsavalas group has revealed that alterations to the monomer feeding profile can aid in understanding cross-linking mechanisms. While symmetric crosslinkers have been extensively studied, a significant number cross-linkers are asymmetric, often containing a terminal allyl moiety for late incorporation into the polymeric network. These asymmetric crosslinkers are often far less studied in the open literature.
Allyl methacrylate (ALMA) is a common crosslinker in various industrial products, yet little is known about its crosslinking mechanism. Bulk polymerization studies have shown ALMA to be an effective crosslinker, albeit without the expected kinetic acceleration due to the Trommsdorff–Norrish effect. This is attributed to the production of stabilized midchain radicals by ALMA, leading to kinetic retardation. Surprisingly, ALMA showed no sensitivity to changes in the monomer feeding profile as expected based on previous work with ethylene glycol dimethacrylate. However, it demonstrated sensitivity to hydrogen abstraction, evidenced by the comparison of the reaction kinetics at 40˚C where chain transfer is unfavored vs 70˚C where chain transfer is more pronounced. Quantum calculations were employed to better understand persulfate and hydroxyl radical attacks on ALMA and n-butyl methacrylate, shedding light on its unique crosslinking mechanism, which has not been reported in the literature to the level of detail discussed in this dissertation.
Terminal allyls offer not only crosslinking benefits but also a solution to the coating industry's challenge of surfactant migration. During the drying process, the local concentration of surfactant, such as sodium dodecyl sulfate, is known to change specifically as surfactant leaves the surface of the latex particle and migrates to the air-water interface during water evaporation. This migration causes coating defects and is especially problematic when it leads to film delamination and water uptake, which can lead to the corrosion of metal substrates. To mitigate this issue, surfmers—surfactants covalently incorporated into the polymer—have been investigated. A library of five biobased surfmers was prepared and tested to determine their critical micelle concentration and their ability to act as colloidal stabilizers. Two surfmers demonstrated crosslinking capabilities, leading to a higher gel fraction, indicating their incorporation into the growing polymer chains. All five surfmers effectively stabilized polymer colloids without significantly affecting reaction kinetics. Among these, only the succinic-based surfmer showed improved stability, which can be explained by the ability of the sulfate group to diffuse to the polymer-water interface.
Angewandte Chemie. doi: 10.1002/ange.202404290
American Journal of Obstetrics & Gynecology. doi: 10.1016/j.ajog.2024.02.177
The Journal of Physical Chemistry B. doi: 10.1021/acs.jpcb.4c00522
Proteins: Structure, Function, Bioinformatics. doi: 10.1002/prot.26685
Journal of Chemical Information and Modeling. doi: 10.1021/acs.jcim.3c01933
American Journal of Obstetrics & Gynecology. doi: 10.1016/j.ajog.2022.12.156
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering.
DISSERTATION ABSTRACT:
Self-assembly is a fundamental process in nature that refers to the spontaneous organization of individual molecules into larger and more complex structures. In recent decades, self-assembly has gained increased importance in materials science, as it enables the production of functional materials with tailored properties using carefully designed particles as building blocks. A promising direction within this realm of research involves the use of lobed colloidal particles to produce porous biomaterials with a wide range of practical applications, including tissue regeneration and catalysis. Given the growing interest in this topic, my dissertation work is mainly focused on conducting modeling and simulation studies on the behavior of lobed particles undergoing self-assembly. More specifically, I investigated the dynamics of lobed colloid particles and explored the influence of varying the particle shapes and environmental factors as they relate to the morphological properties of the final structures. To achieve this goal, I performed molecular dynamics (MD) simulations of a diverse set of lobed particles under different conditions. I considered distinct design variables, including the number, size, and positioning of lobes on the particle surface, allowing for a detailed exploration of the impact of particle characteristics on the properties of self- assembled structures. In these systems, self-assembly is mediated by attractive interactions between the lobes of different particles. For this reason, I investigated the role of distinct types of interactions in determining the morphology and porosity of the self-assembled structures by altering both their strength and nature (uncharged, heterogeneously-charged, homogeneously-charged or functionalized) in different simulations.
As a result of this thorough analysis, I identified the most favorable particle designs and system conditions that promote the creation of large-scale porous structures with tailored characteristics. In addition to studies focused on lobed particles, I also performed simulations of systems comprised of metal-organic frameworks (MOFs) and biologically relevant organic analytes. Several MOFs present the ability to convert chemical interactions into electrical signals, making them promising materials for electroanalytical applications. In the final part of my dissertation, I employed MD simulations to elucidate how organic analytes interact with MOFs at the atomic level. This work provided a deeper insight into how different molecular interactions dictate the adsorption of organic molecules on conductive MOFs and give rise to distinct electrochemical responses. In conclusion, this dissertation highlights the significance of self-assembly phenomena for the development of novel biomaterials, particularly within the context of lobed colloidal particles and MOFs. The utilization of MD simulations allowed investigations of the self-assembly processes at a level of detail that is often challenging to achieve through traditional experimental methods. These simulations also provided additional knowledge on the intricacies that influence the creation of tailored porous biomaterials from lobed particles and elucidated the different ways that organic molecules interact with MOFs during adsorption.
Advanced Functional Materials. doi: 10.1002/adfm.202309567
Advanced Materials Interfaces. doi: 10.1002/admi.202300369
Materials Characterization, 207, 113594. doi: 10.1016/j.matchar.2023.113594
Advanced Materials Technologies. doi: 10.1002/admt.202301517
JOM. doi: 10.1007/s11837-023-06158-x
Materials Science and Engineering: A, 887, 145754. doi: 10.1016/j.msea.2023.145754
ASME 2023 18th International Manufacturing Science and Engineering Conference. doi: 10.1115/MSEC2023-104321
ASME 2023 18th International Manufacturing Science and Engineering Conference. doi: 10.1115/MSEC2023-104324
ASME 2023 18th International Manufacturing Science and Engineering Conference. doi: 10.1115/MSEC2023-104454
ASME 2023 18th International Manufacturing Science and Engineering Conference. doi: 10.1115/MSEC2023-104235
ASME 2023 18th International Manufacturing Science and Engineering Conference. doi: 10.1115/MSEC2023-104233
Acta Materialia, 261, 119395. doi:10.1016/j.actamat.2023.119395
American Society for Composites 2023. doi: 10.12783/asc38/36636
American Society for Composites 2023. doi: 10.12783/asc38/36596
Journal of Materials Research and Technology. doi: 10.1016/j.jmrt.2023.09.079
Submitted to Dartmouth College in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Porous organic materials with designable structures, large surface areas, low densities, and unique electronic and optical properties have found widespread applications in adsorption, separation, energy storage, and catalysis. However, the majority of organic porous materials are synthesized as fluffy powders, which poses two fundamental challenges for them. Firstly, they lack a single-crystal structure at the microscopic scale, making it difficult to study the specific pore size, shape, and potential substrate binding sites at the atomic level and further establish the structure-property relationship. Secondly, they lack the general processing method and macroscopic shape design, making it difficult to manufacture suitable components for specific applications in real-world settings. Such deficiencies can also potentially impact the material's mass transfer efficiency and other performance aspects. In this thesis, based on my research on porous organic materials, I propose my thoughts and design to help solve the two challenges mentioned.
Firstly, I discussed why we need single crystals and how to synthesize a single-crystalline covalently connected framework. (1) I present examples of the fundamental study of host-guest and guest-guest interactions of multiple guest molecules within a hydrogen-bonded organic framework (HOF) through single-crystal structure analysis. (2) Using our group's unique method for designing hydrogen-bonded cross-linked organic frameworks (HCOFs), I demonstrate the synthesis of single-crystal ionic HCOF-7 with halogen bonding and anion exchanging active sites, which is utilized for both I2 and I- at high temperatures.
Second, I introduce 3D-printing technology to fabricate porous organic materials with macroscopic structures. (1) For the first time, I describe a general method for largescale synthesis of 3D-printable imine-based covalent organic frameworks (COFs) using the hierarchical self-assembly enabled template synthesis. (2) I discovered that the template synthesis-based 3D printing technique could also be employed for the fabrication of covalently cross-linked amorphous porous polymers with nano-tubular cavities, which could be used for highly efficient natural product separation.
Overall, by integrating knowledge from different fields, I aim to help connect the micro to the macro and establish bridges between the molecular design, materials properties, and real-life application of porous organic materials.
Scientific Reports doi: 10.1038/s41598-023-41947-z
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science In Mechanical Engineering.
THESIS ABSTRACT:
Incremental sheet forming (ISF) was invented to make sheet metal manufacturing more flexible, enabling rapid prototyping. However, it was initially plagued with inaccurate tolerances. With the advent of double-sided incremental forming (DSIF) more accurate sheet metal parts are capable and thus has received more interest from industry in recent years. In this thesis, the effects of both temperature control, using a vortex tube with compressed shop air, and deformation path, utilizing a reverse, reforming sequence, have on the strain induced γ-austenite to a’-martensite phase transformation in stainless steel 304L (SS304L) during double sided incremental forming were studied on a pyramidal geometry. The results show that reducing the temperature of the SS304L during deformation increases the achievable a’-martensite volume fraction (MVF), which corroborates past research findings. The study also demonstrates that implementing the reforming process increases the MVF, achieving ~90% transformation along the entire formed wall when the temperature is reduced. The ability to manipulate the γ-austenite to a’-martensite transformation from <10% to ~90% by controlling these two parameters demonstrates the ability to tailor the final material properties during incremental forming for the given application.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Mechanical Engineering.
DISSERTATION ABSTRACT:
Stress superposition is defined as the incorporation of additional stresses into an existing manufacturing process during a single operation. In this thesis, experiments, simulations, and modeling of stress superposition in sheet metal deformation were investigated. Stress superposition can be used in manufacturing to reduce forming forces, increase material formability, and tailor the final part properties of products according to their intended applications, creating so-called functionally graded materials. Austenitic stainless steels (SS) were the focus due to their susceptibility to strain-induced phase transformation from austenite to martensite based on the stress state applied. In the first chapter, a novel cruciform specimen was designed to improve material characterization and modeling, which were essential to accurately determine how to adjust the parameters of the manufacturing processes to affect the final part properties. Next, parameters were identified for a martensitic transformation kinetics model experimentally and implemented into a single point incremental forming finite element model. The simulations were validated by experimental results for a truncated square pyramid. After that, To demonstrate the stress superposition strategy with corresponding finite element analyses, the superposition of tensile and compressive stresses into single point incremental forming was used to vary the phase transformation in the formed parts. Then, the continuous bending under tension process was used to investigate the residual stress development and phase transformation under the complex stress states inherent to the process. In future research, these results will inform further studies focused on exploiting stress superposition to improve metal forming processes, e.g., manufacturing heterogeneous trauma fixation hardware components, i.e., implants to hold fractured bones together during healing, using double-sided incremental forming as a proof-of-concept for the application of this work in industry.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Waterborne technology highlights the advantage of using water as the dispersed media to replace the need for organic solvents. Emulsion polymerization is one of the most important techniques to produce functional polymer colloids of industrial importance. Besides the choice of monomers in the reaction, composite particle morphology significantly influences the mechanical properties of the materials in the applications of architectural coatings, adhesives, printing inks, and impact-resistant plastics. Generally, emulsion polymerization produces spherical particles in the presence of water due to surface tension forces. In seeded emulsion polymerization, composite particles containing two incompatible phases can lead to various anomalous structures in either an equilibrium state (thermodynamic control) or a non-equilibrium state (kinetic control). Both oligomer diffusion and polymer diffusion after termination dictate the process of morphological transition. Non-equilibrium states usually describe the structure restricted by polymer diffusion without achieving the lowest energy configuration. The diffusion coefficient during the reaction is not constant but dynamically changes in response to the varying reaction conditions. Morphology control in a non-equilibrium state remains an essential subject of study, as it has yet to be fully understood. This thesis primarily focuses on the mechanistic perspective of non-equilibrium morphology by investigating polymer diffusion and oligomer radial penetration in local conditions. The aim is to establish guidelines and methods in morphology prediction.
In seeded emulsion polymerization, glassy preseeds (Tg,seed ≫ Trxn) limit the diffusion of incoming oligomers resulting in the formation of second-stage polymers in the outer region of the composite particles due to high internal viscosity. Although non-spherical particles (lobed particles) in the system of poly(methyl methacrylate)/poly(hexyl methacrylate-co-styrene)(P(MMA)/P(HMA-co-STY)) was previously reported, the detailed mechanism and their morphological features have not been fully explored. Several possible morphological features are revealed, and relevant parameters are determined. The size of the particles and the weight ratio of the 1st and 2nd stage polymer significantly impact the structure. Through the post-annealing process, it is feasible to achieve a non-equilibrium morphology with a controlled number of lobes on the surface of the particle. On the other hand, a dynamic simulation approach was established to predict radical diffusion behaviors when radical penetration is allowed. The simulated results, including thermal properties (Tg) and morphological features, agree with the experimental observations reported in the literature.
Lastly, the applications of functional polymer colloids were investigated in seeded emulsion polymerization. The 3D porous scaffold was produced through the assembly of multilobed particles. The findings indicate that the non-spherical nature of particles effectively promotes porosity compared to spherical particles. Furthermore, catechol-functionalized adhesives were successfully synthesized with a carefully selected monomer pair under a starved condition. A high-conversion latex is obtained without any side reaction with the presence of oxidizing agents in the radical polymerization.
Journal of Chemical Theory and Computation doi: 10.1021/acs.jctc.3c00406
Chem doi: 10.1016/j.chempr.2023.07.020
Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity, 475–485. doi: 10.1007/978-3-031-40920-2_49.
International Journal of Pharmaceutics. doi: 10.1016/j.ijpharm.2023.123299
Bioengineering. doi: 10.3390/bioengineering10080889
Journal of Chemical Information and Modeling. doi: 10.1021/acs.jcim.3c00835
Journal of Environmental Policy & Planning. doi: 10.1080/1523908X.2023.2229247
Protein Science doi: 10.1002/pro.4720
AIP Conference Proceedings. doi: 10.1063/5.0145202
Journal of Materials Research and Technology doi: 10.1016/j.jmrt.2023.06.059
Proceedings of the IISE Annual Conference & Expo 2023.
Proceedings of the IISE Annual Conference & Expo 2023.
Proceedings of the IISE Annual Conference & Expo 2023.
Proceedings of the IISE Annual Conference & Expo 2023.
Journal of Medical Devices doi: 10.1115/1.4062492
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy In Chemical Engineering.
DISSERTATION ABSTRACT:
Sepsis is a complicated medical emergency and critically ill patients suffering from infectious diseases are at a high risk for developing and dying from sepsis. According to a recent (2019) cohort study from six United States hospitals, suboptimal care (e.g., delay in antibiotics, inappropriate antibiotic therapy) is responsible for 22.7 % of in-hospital sepsis-associated deaths. In September 2020, the World Health Organization called on the scientific community to develop rapid, effective, and affordable tools to improve diagnosis, surveillance, and treatment of sepsis. Our long-term goal throughout this project is to develop a cyclodextrin (CD) impedimetric tongue that can provide early warning of sepsis by continuous monitoring the course of the disease and real-time profiling of urine samples in hospitalized patients. The cyclodextrin impedimetric tongue will also enable healthcare professionals to closely monitor the patients, predict sensitivity and resistance to therapies, decide about the dose of medications, and develop more effective personalized therapies for septic patients. Cyclodextrins, oligosaccharides with a hydrophobic cavity and a hydrophilic surface, are promising biorecognition elements in development of reusable impedimetric tongues. Cyclodextrins can semi-selectively detect different metabolites in the solutions through hydrophobic interactions, Van der Waals forces, and hydrogen bonding. The first aim of this thesis was to develop the first reusable nanostructured cyclodextrin platform using αCD and a weak surface αCD mediator: polyethylene glycol (PEG). To create the Gold-PEG:αCD surface, gold surface was modified with PEG via thiol-gold chemistry and the PEG support enabled reversible immobilization of αCD. We investigated the performance of this platform for detection of a XVI model hydrophobic analyte, trans-resveratrol. Non-faradaic electrochemical impedance spectroscopy (EIS) measurement of the surface suggested that when αCD surfaces are introduced to a solution containing trans-resveratrol, αCD molecules leave the PEG support to interact with trans-resveratrol in the solution. After use, the surface could be regenerated by reloading of αCD. The second aim of this thesis was to improve the stability and reusability of cyclodextrin sensing platform by replacing gold-thiol bonds with carbon-carbon covalent bonds between glassy carbon (GC) and 4-carboxyphenyl diazonium salt. The GC-carboxyphenyl was modified with polypropylene glycol (PPG) through EDC/NHS chemistry. The PPG surface was then loaded with βCD. We used the GC-carboxyphenyl-PPG:βCD surface for sensitive detection of cortisol in biofluids (i.e., urine and saliva), and demonstrated the successful regeneration and reuse of the GC-carboxyphenyl-PPG:βCD surface for ten times. Finally, we employed sensitive, stable, and reusable cyclodextrin nanostructured surfaces to develop the first-generation cyclodextrin impedimetric tongue for separation and classification of four classes of bioanalytes including creatinine, cortisol, glucose, and fumarate. We applied linear discriminant analysis (LDA) to integrate and map the data, and by using the normalized changes in imaginary capacitance of three cyclodextrin surfaces (γCD at 79 Hz, hydroxypropyl-βCD at 0.25 Hz, and hydroxypropyl-γCD at 63.34 Hz), we achieved the 5-fold cross validation accuracy of 69%. Different methods of data preparation, EIS signal processing, and determining the characteristic frequencies of different analytes and single frequencies of cyclodextrin surfaces affect the accuracy of the impedimetric tongue. By optimizing these parameters, we can improve the performance and accuracy of the impedimetric tongue and apply this device for point of need applications.
Submitted to Dartmouth College in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Additive manufacturing, more commonly known as 3D-printing, is bringing about a grand technological transformation in material design and fabrication. In contrast to traditional fabrication techniques, 3D-printing features rapid prototyping, complex and customized 3D structural designs, and multi-material integration. Among current 3D-printing systems, direct-ink-writing (DIW) exhibits unique functionalities due to its mild operation conditions and the ability to integrate various organic and inorganic entities. Although supramolecular binding motifs are increasingly utilized in 3D-printing designs, the optimization of 3D-printable inks remains largely empirical. In this thesis, we present two strategies to rationally design supramolecularly crosslinked 3D-printable hydrogels, including (1) micro-crystallization and (2) hierarchical co-assembly-enabled DIW 3D-printing. We also highlight the follow-up applications using either of the strategies and the design principles when aiming for a specific purpose.
First, we designed a 3D-printable hydrogel using the micro-crystallization of polypseudorotaxanes via kinetic trapping. The installation of stoppers and/or speed bumps on polymer chain ends enabled the formation of kinetically trapped polypseudorotaxane networks suitable for DIW 3D-printing. We systematically studied the assembly between polyethylene glycol (PEG) and α-CD and established a clear structure-property relationship. Harnessing the kinetic trapping characteristic, we designed 3D-printed heterostructures composed of two polyrotaxane networks, which were able to shape morph upon moisture variations.
Second, we applied the kinetic trapping principles to design 3D-printable pro-slide-ring crosslinker hydrogels composed of PEG and γ-CD. The supramolecularly crosslinked hydrogels were thereafter converted to crystalline-domain-reinforced slide-ring materials. Here, the micro-crystallization not only enabled 3D-printing but also reinforced the hydrogel material in terms of rigidity. The slide-ring cross-linkages and the crystalline domains overcame the trade-offs between toughness and elasticity, with the structure-property relationship elucidated through high-throughput synthesis and machine learning. The hydrogels were fabricated into high-performance capacitive stress sensors to demonstrate their excellent mechanical properties and material versatility.
Third, we introduced our efforts of using the hierarchical co-assembly strategy to develop 3D-printable 1,3,5-tricarboxamide (BTA) materials. We designed and synthesized 12 BTA monomers and employed them for two applications, including liquid crystalline materials for optical property modulations and the construction of tough hydrogel materials. Molecularly, we studied the self-assembly and co-assembly of BTA motifs, particularly in a crosslinked network. Macroscopically, we synthesized BTA-based crosslinked networks for optical and mechanical property investigations to correlate the structural information molecularly. We also demonstrated the construction of 3D-printed BTA materials, exhibiting superior features compared to materials synthesized in bulk.
Submitted to the University of New Hampshire In Partial Fulfillment of The Requirements for the Degree of Doctor of Philosophy in Chemical Engineering.
DISSERTATION ABSTRACT:
In this dissertation, I developed and investigated gelatin-based microporous injectable hydrogels for the encapsulation of stem cells for multiple applications in cell delivery. Utilizing microgels composed from a mixture of gelatin and modified gelatin, I demonstrated the utility of a dual crosslinking mechanism, which enabled rapid gelation and tissue adhesion with improved cytocompatibility. Mesenchymal stem cells (MSCs) encapsulated in this hydrogel proliferated at a more rapid rate than in a nonporous counterpart, and showed increased immunomodulatory potential. Then, I investigated gelatin microporous hydrogel for the encapsulation of MSCs for bone tissue regeneration. Encapsulated cells more readily differentiated into osteoblasts (i.e. boneforming cells) in the microporous environment observed by morphological changes and quantitative assays. This is believed to be due to enhanced cell spreading and cell-cell communication in the unique 3D environment provided to the cells by the microporous hydrogel. Transcriptomic analysis was performed by mRNA sequencing (RNA-seq) of MSCs encapsulated in the differing 3D microenvironments. Results indicated that the 3D environment influenced the expression of genes that are related to cell adhesions, cell-cell interactions, cytoskeletal organization, and matrix remodeling, in addition to MSC differentiation. Because neuronal development is highly dependent on cell-cell communication, I encapsulated an established neural stem cell line (ReNcell) in gelatin microporous hydrogel to investigate neuronal differentiation in comparison to a nonporous analog. Laminin was chemically conjugated to microgel surfaces, which controlled the organization of encapsulated cells in the hydrogel environment. Cell differentiation was examined by immunofluorescence staining, and JC-1 assay was utilized to examine mitochondrial membrane polarization. The microporous hydrogel xii induced substantially greater cell spreading, morphological changes and cell-cell connections than nonporous hydrogel. The majority of the cells in the microporous hydrogel differentiated into neural lineages, evidenced by immunostaining by MAP2 and GFAP. In summary, this work demonstrates the utility of gelatin microporous injectable hydrogels for applications in in situ cell encapsulation and stem cell delivery for tissue regeneration.
CIRP Annals doi: 10.1016/j.cirp.2023.04.015
Dissertation submitted to the Department of Chemistry and the University of Wyoming in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Nanomaterials are a unique class of materials that exhibit unique chemical and physical properties due to their nanoscale dimensions. These properties make nanomaterials well-suited for use in sensing applications, particularly in the development of electrochemical sensors and biosensors. With a wide range of nanoparticle types available, differing in size, shape, and composition, the applications for nanomaterials in electroanalysis are broad and expanding. In particular, well-ordered nanoparticle arrays are attractive platforms for a variety of analytical applications. However, the fabrication of such arrays is generally challenging due to the difficulty of controlling individual nanoparticle nucleation and growth events. This is where Scanning Electrochemical Cell Microscopy (SECCM) comes in. SECCM is a versatile nanofabrication tool that enables the synthesis of individual nanoparticles of controlled size at precisely defined locations on a sample with high spatial resolution (<100 nm). SECCM allows for the fabrication of ordered nanoparticle arrays where individual nucleation and growth events can be detected and controlled, resulting in nanoparticles of controlled size. One application of this technology is developing electrochemical sensors and biosensors, where gold nanoparticles can be modified with biorecognition elements like thiol compounds to detect specific biomolecules. The ability to fabricate well-ordered nanoparticle arrays with controlled size and position using SECCM makes it an ideal tool for developing such sensing devices, providing a powerful and flexible platform for nanofabrication in electrochemical sensing applications.
Small doi: 10.1002/smll.202300323
Applied Geography. doi: 10.1016/j.apgeog.2023.102942
Macromolecules doi: 10.1021/acs.macromol.2c02378
Ecology & Society. doi: 10.5751/ES-13739-280151.
Nano LIFE doi: 10.1142/S1793984423300017
Journal of Chemical Education doi: 10.1021/acs.jchemed.2c00922
Chemical Society Reviews doi: 10.1039/D2CS01011A
Korean Journal of Chemical Engineering doi: 10.1007/s11814-022-1293-y
Journal of Chemical Information and Modeling doi: 10.1021/acs.jcim.2c01487
Materials doi: 10.3390/ma16020572
ACS Applied Bio Materials doi: 10.1021/acsabm.2c00910
Journal of the American Chemical Society doi: 10.1021/jacs.2c05510
ACS Nano. doi: 10.1021/acsnano.2c02529
Computer Methods in Applied Mechanics and Engineering. doi: 10.1016/j.cma.2022.115740
ACS Nano doi: 10.1021/acsnano.2c09336
Accounts of Materials Research. doi: 10.1021/accountsmr.2c00173
Biofabrication doi: 10.1088/1758-5090/ac94a1
Current Opinion in Electrochemistry, 37, 101164. doi: 10.1016/j.coelec.2022.101164
Mechanics of Materials. doi: 10.1016/j.mechmat.2022.104480
Ecological Economics doi: 10.1016/j.ecolecon.2022.107624
Book chapter in "Advanced Spectroscopic Methods to Study Biomolecular Structure and Dynamics" doi: 10.1016/B978-0-323-99127-8.00011-8
ASME 2022 17th International Manufacturing Science and Engineering Conference doi: 10.1115/MSEC2022-85595
Environmental Management doi: 10.1007/s00267-022-01715-7
Renewable and Sustainable Energy Reviews doi: 10.1016/j.rser.2022.112898
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
The aim of this dissertation is to provide insight into synthetic materials that replicate the function and structure of natural materials. First, a comprehensive overview of the challenges and recent advances in tailored synthetic molecular recognition through molecularly imprinted polymers (MIPs) will be presented. Chapter 2 of this work discusses the synthesis of azlactonebased homopolymers as functional polymers tuned for the detection of opioid molecules. Through the rapid and efficient ring-opening reaction of azlactone pendant chains with primary amines, customized functionalization of the homopolymers with receptor-like moieties was achieved post-polymerization. Chapter 3 explores the use of functionalized diblock copolymers as protein mimics for single-chain nanoparticle (SCNP) collapse. The collapse was successful by use of a newer, one-pot deprotection and coupling Sonogashira-like reaction without coppercatalyst. The polymers and associated nanoparticles were analyzed by size-exclusion chromatography equipped with a multi-angle light scattering (SEC-MALS) detector. Shifts in retention time from polymer to nanoparticle was indicative of change in hydrodynamic volume, suggesting that the polymer was folded into SCNP. Chapter 4 investigates the use of functionalized diblock copolymers with Diels—Alder reaction compatible monomers to form SCNP. Like Chapter 4, shifts in the retention time were observed between polymer and nanoparticle, and SCNP formation discussed.
Proceedings of the ASEE 2022 Annual Conference. https://peer.asee.org/41107
European Journal of Mechanics - A/Solids, 96, 104775. doi: 10.1016/j.euromechsol.2022.104775
Journal of Medical Devices. doi: 10.1115/1.4055249
Portico. doi: 10.1002/prot.26410
ACS Applied Materials & Interfaces, 14(37), 42374–42387. doi: 10.1021/acsami.2c07701
2022 ASEE Annual Conference & Exposition
International Journal of Computational Materials Science and Engineering doi: 10.1142/S2047684122500154
Journal of Chemical Information and Modeling, 62(14), 3381–3390. doi: 10.1021/acs.jcim.2c00376
Frontiers in Physics doi: 10.3389/fphy.2022.936385
International Journal of Plasticity, 156, 103367. doi: 10.1016/j.ijplas.2022.103367
Journal of Dynamic Behavior of Materials. doi: 10.1007/s40870-022-00344-9
STAR Protocols. doi: 10.1016/j.xpro.2022.101523
Microelectronic Engineering doi: 10.1016/j.mee.2022.111835
IOP Conference Series: Materials Science and Engineering doi: 10.1088/1757-899x/1238/1/012085
Journal of Micro and Nano-Manufacturing doi:10.1115/1.4055474
Proceedings for IISE Annual Conference & Expo 2022
Proceedings of the IISE Annual Conference & Expo 2022.
ACS Applied Bio Materials doi: 10.1021/acsabm.2c00214
Polymer Chemistry doi: 10.1039/D1PY01472B
Proteins: Structure, Function, and Bioinformatics doi: 10.1002/prot.26385
International Journal of Mechanical Sciences doi: 10.1016/j.ijmecsci.2022.107663
CIRP Annals doi: 10.1016/j.cirp.2022.04.059
Submitted to the University of New Hampshire In Partial fulfillment of The Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Certain organisms living in cold regions have adapted different strategies to survive in harshly cold temperatures. Some of them use freeze-avoiding strategies in which they can prevent freezing by controlling the concentration of sugars (et. sucrose, trehalose) or polyols (glycerol), regulation of the ice nucleator, and dehydration. Other organisms have adapted to this extremely cold condition by producing antifreeze (gly)proteins (AF(G)Ps) which exhibit ice recrystallization inhibition (IRI), thermal hysteresis activity (THA), and dynamic ice crystal shaping. These proteins discovered in Antarctic fish in 1960 for the first time have been reported in bacteria, fungi, insects, and plants. AF(G)Ps and their synthetic biomimetics have received increasing attention as potential candidates for various industrial and bio-medical applications. Promising results from vitrification and other protocols using antifreeze agents with ice recrystallization inhibition activity have widely been reported in biopreservation. Conversely, understanding of the antifreezing process caused by these macromolecules remains under challenge. This is due to the multifunctional nature of the freezing process and antifreeze macromolecule’s behavior which brings complexity in designing the synthetic antifreeze structures. In addition, the cost, low availability, toxicity at higher concentrations, and instability beside several other drawbacks make their large-scale production challenging. Although several synthetic attempts for the exploitation of AFPs have been studied in the past, challenges remain in the synthetic design of AFP analogs. On the other hand, poly (vinyl alcohol) (PVA) with simple structure has been reported with potent IRI activity as a good candidate for large-scale production and applications.
Our group has explored structural variations to polyol-based polymers to contrast with PVA as a control and identified several key structural elements for performance in IRI, THA, as well as in ice nucleation inhibition (INI). These structural features are bioinspired by the typical ice-binding plane of AFPs yet are surprisingly simple to produce with potency approaching that of typical AFPs. Key to the performance is positioning small organic functionalities with known antifreeze properties (glycerol) pendent to a host polymer chain with consideration of their conformational freedom. To build systematic variations into both the backbone and side-chain structures, we used poly (vinyl alcohol), poly (isopropenyl acetate), poly (acrylic acid), and poly(methacrylic acid) xvi parent polymers for such pendent modifications. One structure in particular, glycerol-grafted-PVA (G-g-PVA), shows potency rivaling that of AFPs at similar micromolar concentration. The findings in this study help guide the rational design of synthetic antifreeze polymers useful for applications such as anti-icing coatings through to cryopreservation methods for organ transport and cell preservation.
While AFPs are well-known for their ice nucleation and recrystallization inhibition activity along with controlling the ice crystal morphology, the contrasting behavior of ice nucleation promotion by AFPs and its key contribution to the whole antifreezing process also seems necessary to explore in this context. Here, silver iodide (AgI) has been used as an ice nucleator in different polymer solutions in ultra-pure water (UPW) to imitate the ice nucleation process by AFPs. PVA prepared by RAFT polymerization and our glycerol grafted derivative (G-g-PVA), now shown to be the most IRI active polymer to date, was investigated for its ice nucleation and recrystallization activity in AgI dispersion media. The results showed that the ice nucleation rate and temperature was significantly changed by adding the AgI dispersion in PVA and G-g-PVA solutions. The polymer solution in UPW containing AgI dispersion showed significant improvement in IRI activity compared the same polymer in PBS buffer solution. Our results demonstrate the considerable contribution of the ice nucleator in ice nucleation rate and temperature which enhances IRI activity of synthetic antifreeze polymers. These finding both aid our understanding of the ice nucleation promotion impact on synthetic polymers IRI activity along with engineering biomimetics for biomedical and industrial applications.
Next, we focused our efforts to transfer these functionalities and performance to the solid-state interface with water. Aqueous dispersions of polymeric colloidal particles served as this substrate and were functionalized with either PVA or G-g-PVA grafted to their surfaces to contrast with performance of the same polymers strictly in the solution state. These functionalized colloids also can be applied as a continuous coating through latex film formation to assess anti-icing and iceadhesion properties. While these systems also showed encouraging and potent activity, their performance was not enhanced compared to that of the solution state systems. This may have implications for fully solid-state anti-icing coatings, yet our attention then shifted from this scope of work to new funding which required again a solution state approach.
In this final application, we explored PVA and G-g-PVA synthesized in our lab for their biopreservation aspects especially for red blood cell (RBC) cryopreservation at -80 °C. Our results again confirmed G-g-PVA to be an excellent candidate for cryopreservation and quite likely for organ cryopreservation. Using this polymer in solution as a cryoprotectant for RBCs showed significant improvement to controls, preventing hemolysis (cell rupture) along with eliminating other drawbacks that have been observed when using small molecule cryoprotective agents like glycerol, dimethyl sulfoxide (DMSO), etc.; especially with regard to the ability to fully remove all traces of the cryoprotectant after cryopreservation storage and thawing.
In summary, the studies in this dissertation provide critical insights and approaches for the understanding of the freezing process and ideas that can help understand relevant mechanisms of influencing key freezing steps that have not yet been fully understood. In addition, it provides guidelines to synthesize G-g-PVA, currently the most potent active polymer in terms of IRI and THA shown useful for several high impact applications. In particular, this research provides valuable data and experimental conditions to understand the IRI mechanism to use in engineering next generation highly efficient antifreeze systems.
Submitted to the University of New Hampshire In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy In Chemical Engineering.
DISSERTATION ABSTRACT:
In this dissertation I investigated the structural properties of melanin biopigment from different sources as an antibacterial and endotoxin bonding agent. I extracted melanin from Equus ferus hair with acid hydrolysis (termed EquusMel) and characterized it by microscopic and spectroscopic techniques. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that EquusMel is mainly elliptical in shape with a mesoporous and layered structure within the individual particles. Wide-angle (WAXS) and small-angle (SAXS) Xray scattering measurements demonstrated a semicrystalline multilayered structure with order spacing of 45.2 Å. Pore size distribution determined by the Barrett–Joyner–Halenda (BJH) method showed primary pores within the range of 30–50 Å. Nitrogen adsorption–desorption isotherms exhibited a Brunaur–Emmett–Teller (BET) surface area of 3 m2 /g. Raman, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) spectra revealed similar chemical signature between EquusMel and synthetic melanin (SynMel). I investigated the antibacterial effect and its mechanism of action for EquusMel. I found that EquusMel has distinct antibacterial activity due to its potential to generate reactive oxygen species (ROS). ROS generated via oxidation of catechols is considered the main mechanism of antibacterial activity. The simplicity of EquusMel extraction and its antibacterial property allows this biomaterial to be xvi applicable to a variety of areas. Zinc cations (Zn2+) were loaded on melanin structure (Mel-Zn) for rapid and selective separation of gram-negative bacteria and lipopolysaccharide (LPS) from blood. Mel-Zn was characterized by XPS and Raman which revealed the successful Zn2+ loading. I identified that Mel-Zn rapidly captures approximately 90% of Escherichia coli in whole blood and 100% of LPS in PBS, which can reduce bacteremia loads and mitigate the spread of these infectious agents to other tissues and organs. Additionally, simultaneous binding to bacteria and LPS could enhance the efficacy of antibiotic therapy. Adsorption of protein from individual protein model solutions, as well as LPS-spiked protein solutions, was found to be minimal. Hemolysis and coagulation assays demonstrate the blood biocompatibility of Mel-Zn, which could be adapted for clinical use in an extracorporeal membrane to remove pathogens and LPS in acute sepsis patients.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science in Chemistry.
THESIS ABSTRACT:
Understanding the properties of bioconjugates and biomaterials has increasingly become the focus of pharmaceutical companies, material scientists, and academia due to their growing list of applications. Bioconjugates have found broad use in therapeutics, drug delivery, tissue engineering, and biosensing. Historically, interest in specific bioconjugates has depended on the cost-availability of the biomacromolecule, making proteins the most well studied, given their relatively low cost and ease of production. However, recent technological advances in plasmid DNA (pDNA) production from E. Coli allow for greater cost-efficiency, changing the landscape ofbiomaterial research. Employing alkylating agents with known chemo-selectivity to nucleophilic sites on DNA, a polymer or polymerization agent can be coupled to biologically derived pDNA. Subsequently, properties of the hybrid-DNA bioconjugate can be controlled via the location of alkylation, to tune degradation rate and stability of the DNA bioconjugate and graft-from polymerization to increase stability and solubility.
Submitted to the University of New Hampshire in Patrial Fulfillment of the Requirements of the Degree of Master of Science in Mechanical Engineering.
THESIS ABSTRACT:
In-plane biaxial testing using a cruciform type specimen is a useful experimental method to characterize the elasto-plastic material behavior under non-uniaxial conditions. Different stress states can be imposed to the specimen simply by varying loading ratios along two orthogonal axes. Experiments can be performed using one experimental setup and one specimen geometry. Among different control options for loading, the displacement control in each arm is a stable and consistent option to keep the static deformation rate. However, a non-linear relationship exists between the control parameter e.g., displacement, and derived quantities, e.g., stress and strain. Therefore, it is a challenge to achieve desired deformation paths in the main deformation area of the specimen. In this document, an interpolation method to systematically determine nonlinear displacement paths is implemented using the finite element simulation method to produce linear stress and strain paths in the center of a cruciform specimen geometry. Interpolation is first applied to an AISI 1008 steel specimen, in which a previously interpolated linear strain path is improved with another iteration of interpolation. Interpolation is then expanded to produce displacement paths resulting in linear stress paths, having a constant stress triaxiality, for five different stress states of a SS304L cruciform specimen. The versatility of the interpolation method is displayed through the successful implementation for both strain and stress linearization as well as with two different materials and two specimen geometries.
DISSERTATION ABSTRACT:
Total joint devices that can survive more than 20 years in vivo require a bearing surface that can combine toughness, wear resistance, and chemical stability. Ultrahigh molecular weight polyethylene (UHMWPE) remains the gold standard for these bearings, having been utilized as a liner and bearing surface for over five decades. Well-documented material trade-offs lead to failure modes that suggest that hip liners and knee bearing surfaces without optimal processing may be prone to premature failure in the patient. Because the demographic of those receiving implants is changing and smart materials and devices are seeing increased use in medicine, implants may need to be more functional to allow optimization for the patient of the future. The present work explores material trade-offs by attempting to alter the microstructure of UHMWPE through the use of a severe plastic deformation technique known as equal channel angular pressing (ECAP). Work was performed to confirm the validity and reliability of dynamic mechanical analysis (DMA) as a rapid means to indicate and assess changes to the microstructure of UHMWPE in the form of entanglement density and chain interactions. ECAP was applied to both neat and conductive composites of UHMWPE in order to understand the microstructural and mechanical changes due to shearing. Two grades of UHMWPE were used to understand the impact of MW, a variety of temperatures were employed to better optimize shear strain, and consolidation and extrusion hydrostatic pressures were altered to determine if chain mobility and consolidation were hindered under large compressive forces. Preliminary modeling of the different thermal gradients that ECAP and compression molded (CM) controls are exposed to was carried out to aid in and inform future experiments. While ECAP did not reveal changes to the microstructure of neat materials as compared to compression molded (CM) controls, work-to-failure was decreased which is hypothesized to be due to residual stresses. Carbon composites, on the other hand, were shown to have increased work-to-failure after shearing which was coincident with a decline in conductivity as compared to CM controls.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Single-chain nanoparticles (SCNP) are a class of intramolecular cross-linked polymeric nanoparticles with a variety of applications including catalysis, sensors, nanomedicine, and nanoreactors. Such nanoparticles are synthesized by folding or collapsing single polymer molecules. By implementing a single-chain folding technique, the single-chain nanoparticles with uniform degrees of cross-linking are synthesized by parent polymer chains with similar chain lengths and polymer microstructure. Polymer chains that are synthesized by various controlled polymerization techniques can be converted to SCNPs through a variety of covalent chemistry and supramolecular interactions. Based on the expected cross-linking chemistry, related functional groups can be installed either during monomer synthesis or post-polymerization functionalization by utilizing a variety of methodologies. With the goal of effecting catalysis of various organic reactions in aqueous system, we developed a series of ligand functionalized SCNPs with water-soluble pendent groups. N-heterocyclic carbene (NHC) ligands were designed and synthesized to immobilize transition metal cation on SCNPs for catalysis. By employing polymer functionalization strategy, amine-ended ligands, water soluble pendent groups, and cross-linkers were installed by substitution reaction on poly xii (pentafluorophenyl acrylate) (PFPA) synthesized by reversible addition fragmentation transfer polymerization (RAFT), and the process of reaction can be monitored by F19 NMR conveniently. Moreover, to realize inverse temperature dependent controlling, the temperature sensitive watersoluble pendent groups were utilized, such as N-isopropyl amide, which can be installed by the addition of isopropylamine in the process of functionalization of poly (PFPA). Consequently, a variety of organic reactions could be possible in aqueous system catalyzed by combination of different transition metal cations and water-soluble NHC-functionalized SCNP platform.
Drones doi: 10.3390/drones6050100
Computational Materials Science doi: 10.1016/j.commatsci.2022.111348
Mahmud, M.S. (2022) "Healthcare data analytics for wearable sensors". In E.M. Narvaez, C. Dincer (Ed.). Wearable Physical, Chemical and Biological Sensors: Fundamentals, Materials and Applications (pages 169-182). Elsevier. doi: 10.1016/c2019-0-04003-4
Journal of Micro and Nano-Manufacturing doi: 10.1115/1.4055230
Cell Reports Physical Science doi: 10.1016/j.xcrp.2022.100786
BioOne Complete
UNH Today
Journal of Applied Polymer Science doi: 10.1002/app.52175
ACS Applied Polymer Materials. doi: 10.1021/acsapm.1c01312
International Journal of Molecular Sciences. doi: 10.3390/ijms222413481
Polymer Chemistry. doi: 10.1039/D1PY01005K
ACS Applied Materials & Interfaces doi: 10.1021/acsami.1c14453
ACS Applied Materials & Interfaces. doi: 10.1021/acsami.1c14453
Angewandte Chemie International Edition. doi: 10.1002/anie.202113665
Angewandte Chemie International Edition. doi: 10.1002/anie.202113569
Chemical Society Reviews doi: 10.1039/d1cs00600b
Chemical Society Reviews. doi 10.1039/d1cs00600b
DISSERTATION ABSTRACT:
Metal–Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) are emerging materials with multifunctional properties that allow them to address global issues in chemical separations and sequestration, chemical sensing, and energy storage and conversion. Many of these applications rely on the ensemble of host–guest interactions between targeted molecular species and the surface of the framework to imbue selective properties that enhance applied performance metrics. Design principles guiding the construction of materials with desired surface chemistry and functionality are lacking for framework materials targeted towards chemical sensing. A better fundamental understanding of how host–guest interactions inform function and how host sites can be designed into a framework system through bottom-up synthetic techniques is required to advance the field of framework materials for electroanalysis. In four chapters, this thesis provides insight into the role of surface chemistry in chemical sensing in both the liquid and gas phase and how the interplay between surface chemistry and conductivity can be controlled by the strategic choice of starting materials and material morphology to produce materials with robust capabilities in chemicals sensing.
Frontiers in Chemistry. doi: 10.3389/fchem.2021.753635
Biophysical Journal. doi: 10.1016/j.bpj.2021.10.007
International Journal of Computational Materials Science and Engineering. doi: 10.1142/s2047684121500329
Frontiers in Physics. doi: 10.3389/fphy.2021.767623.
Proteins. doi: 10.1002/prot.26265
Physical Chemistry Chemical Physics. doi: 10.1039/d1cp03822b
Sensors and Actuators Reports. doi: 10.1016/j.snr.2021.100051.
Submitted to the faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Designing 3D printable supramolecular materials that can amplify molecular level functions to macroscale promotes the construction of advanced architectures with superior properties, thus accelerating the development of stimuli-responsive materials into integrated devices. Cyclodextrin-based poly(pseudo)rotaxanes, referred to as polyrotaxanes and polypseudorotaxanes, are ideal candidates to exercise the designing principles of 3D printable mechanically interlocked molecules (MIMs) for functional materials, due to their facile synthetic methods, variable stimuli responsiveness, and excellent biocompatibility. In this thesis, I set out to design 3D-printable cyclodextrin-based poly(pseudo)rotaxanes with their molecular motions synchronized to be amplified at the macroscale, subsequently exploiting designed macroscopic shapes with complex structures to advance their macroscopic machinery behaviors.
First, I identified designing principles to facilitate the 3D printability of MIMs for direct ink writing: (1) tailoring the dynamic interactions between binding motifs, such as hydrogen bonding between cyclodextrins, to allow the shear-thinning and rapid self-healing properties; (2) controlling assembled architectures to reinforce the polymer networks. By synthetically navigating the crystalline inclusion complexes to amorphous products with higher crosslinking degrees via the design of speed bumps or side-chain architectures, crystalline precipitates were converted to viscoelastic hydrogels that are favorable for 3D printing and mechanical adaptability. These insights allow us to design a series of 3D-printable cyclodextrin-based poly(pseudo)rotaxanes with controllable network structures and superior mechanical and responsive properties.
Second, I have also demonstrated an approach to synchronize the molecular motions of the mechanically interlocked rings and amplify them to perform mechanical work by switching the motions of the rings between random shuttling and stationary states through different external stimuli. This allows us to develop a family of actuators or mechanically adaptive materials that respond to solvent, pH, temperature, humidity and cyclodextrins, in which their macroscopic motions and materials properties rely on the control of molecular motions or features and hierarchical control across nano-to-macroscale.
Another interesting class of polyrotaxane materials I discovered are anti-freezing hydrogels with excellent mechanical properties. By noncovalently connecting polyrotaxane and polyacrylamide via hydrogen bonds, the resultant pseudo-slide-ring network hydrogels possess high stretchability, high toughness, good electrical conductivity at sub-zero temperatures, paving the way for a wide range of hydrogel applications under extreme environments.
Journal of Alloys and Compounds. doi: 10.1016/j.jallcom.2021.161871.
Fisheries Management & Ecology doi: 10.1111/fme.12513
Journal of Applied Ecology doi: 10.1111/1365-2664.14009
Materials Horizons. doi: 10.1039/d1mh01108a.
Canadian Journal of Fisheries and Aquatic Sciences doi: 10.1139/cjfas-2020-0402
Angewandte Chemie International Edition. doi: 10.1002/anie.202109987
Materials Science and Engineering: A. doi: 10.1016/j.msea.2021.141876
Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability. doi: 10.1115/MSEC2021-59877.
Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation. doi: 10.1115/msec2021-63658
Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation. doi: 10.1115/msec2021-63471
Proceedings of the 2021 IISE Annual Virtual Conference.
The 12th International Conference on Computational Methods.
Forming the Future. doi: 10.1007/978-3-030-75381-8_166
Forming the Future. doi: 10.1007/978-3-030-75381-8_155
Chem. doi: 10.1016/j.chempr.2021.06.004
JOM. doi: 10.1007/s11837-021-04715-w
JOM. doi: 10.1007/s11837-021-04715-w
Journal of Manufacturing Science and Engineering. doi: 10.1115/1.4051189
CIRP Journal of Manufacturing Science and Technology. doi: 10.1016/j.cirpj.2021.04.006
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Natural Resources and Environmental Studies
DISSERTATION ABSTRACT:
Complex interactions between society, ecology, and the economy have revealed a particularly challenging set of problems in the context of sustainability and sustainable development. Such problems are “wicked” in nature due to their high degree of uncertainty, lack of a shared definition, competing values, complex social-technical interactions, as well as the often contradictory institutional and procedural governmental regulations and frameworks. Such multi-issue, multi-party problems are prevalent in management of social-ecological systems, particularly those surrounding decisions about water resources—given that such problems cannot be tackled via a single discipline, scientists have called for production of new knowledge that informs policy making and advances societal needs. Sustainability science is a new frontier which can help organically integrate science, engineering, and planning, and ultimately support production of actionable science that helps find solutions to urgent human needs, inform long-term planning, and impact policy making at the intersection of human well-being and the protection of the planet’s life support systems. A sustainability science framework is useful for tackling problem-solving around “wicked” water resource management issues, such as decisions about dams.
New England, as much the rest of the world, has been subject to vast landscape alteration and ecological degradation over the past several hundred years. While some view dams as symbols of human ingenuity, others see them as symbols of colonization and environmental degradation. Given that thousands of these dams are reaching the end of their lifespan and pose safety risks, they present unique river restoration opportunities. However, alternative management decisions about dams, such as removal, are associated with various costs and benefits, or tradeoffs. As stakeholders are faced with decisions regarding the fate of aging dams in their communities, they are often confronted with contentious and polarizing arguments about what should be done with a particular dam. Stakeholders’ conflicting interests within the context of the social, ecological, and engineering complexities surrounding dams, often lead to unsuccessful negotiations that make it challenging to make progress toward shared sustainability goals.
This dissertation seeks to improve the current decision-making landscape about dams, and the hard-bargaining negotiation practices that often surround them, by bridging the science-policy divide via 1) addressing knowledge gaps about public and stakeholder perspectives, and 2) advancing collaborative decision-making theory and practice via design, implementation, and evaluation of a science-based role-play negotiation simulation, a novel process of knowledge production tested with stakeholders in New England. The dissertation structure is further organized into three distinct studies. Study 1 explores public opinion surrounding dams in New Hampshire within the context of four tradeoffs—findings reveal that the majority of respondents favor removing dams as opposed to keeping them for preservation of industrial history, property values, or flatwater recreation. Respondents favor keeping dams, however, if they are to be used for electricity generation via hydropower. Additionally, Study 1 results show that younger respondents, women, and liberal-leaning respondents are more likely to support dam removal, although this varies depending on the tradeoff.
The focus of Study 2 was to develop a stakeholder assessment for the state of New Hampshire to inform whether and how fostering a collaborative decision-making process is possible. Specific objectives for Study 2 were to identify 1) the stakeholder groups, priority interests, issues, and decision-making constraints, and 2) barriers and opportunities to fostering collaboration and desired project outcomes. Results from Study 2 reveal that stakeholders are open to collaborating and reimagining the decision-making landscape around dams, but need to overcome substantive and process-related barriers by focusing on opportunities around transparent and participatory decision-making, diversity of public participation platforms and modes of engagement, trust in science and among stakeholders, effective science communication, competent technical consultants, funding availability, and joint fact-finding.
Study 3 examined the extent to which science-based role-play negotiation simulations impact learning, use of science in decision-making, and innovative problem-solving around management of dams in New England. As part of this study, stakeholders engaged in a mock decision-making process (reflecting real-life institutional arrangements and scientific knowledge) for a set period. Tradeoffs between hydropower, fish passage, costs, cultural/historic benefits, recreation, and property values were at the center of this negotiation simulation. By playing an assigned role (different from the participant’s real-life role) while interacting with a computational model across a series of workshops in New Hampshire and Rhode Island, participants had a safe space to learn about each other’s perspectives, develop shared understanding about a complex issue, and collaborate on solving that issue. The role-play was evaluated using data from a mixture of questionnaires, interviews, concept mapping activities, and debriefing sessions. Results from Study 3 indicate that science-based role-plays lead to shifts in cognitive, normative, and relational learning. Results also reveal that stakeholders view immersive knowledge production processes, such as these role-plays, as salient and legitimate products (however, not without some criticism), suggesting that such products can contribute toward bridging the science-to-policy divide in issues surrounding dams. In summary, this dissertation uses mixed-methods to carry out applied, problem-oriented, solutions-driven, and user-inspired research that contributes toward the advancement of theory and practice of sustainability science, while helping address disciplinary gaps and shape decision-making around dams in New England and beyond.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Given the rising of environmental concern, the market of waterborne coating and adhesives has been constantly growing. Polymer latex particles produced by emulsion polymerization are one type of important components in their formulations. Thus, to tune mechanical properties of waterborne coatings and adhesives, one of the common ways is to utilize crosslinkers to form a macromolecular network structure, as known as “gel”, inside of the polymer latex. A major challenge to obtain desired properties of the material is how to control macromolecular architecture, such as sol-gel ratio and crosslinking density. Hence, this dissertation focuses on the study of predicting and controlling macromolecular network architectures in both bulk polymerization and emulsion polymerization. Bulk polymerizations share some similar mechanisms with emulsion polymerization but is simplified by being a homogeneous single phase reaction environment. Emulsion polymerization is a heterogeneous reaction environment with reactions in two phases. Due to the complexity of the emulsion polymerization environment, bulk polymerization is often used xxii as a first test environment to simplify and study new reaction systems. Based on our previous work, a reduced reactivity parameter, Ψ, was introduced and applied to precisely describe the reactivity of crosslinking sites (pendent vinyl groups from crosslinker monomers). Most of our prior work used the bulk polymerization environment and here we now also extend to the emulsion polymerization environment. In addition to crosslinking reaction kinetics, we also explored macromolecular structure development as predicted by a hybrid Monte Carlo Model. Chapter 3 and Chapter 4 significantly extended our previous work. Chapter 3 explored a wide matrix of monomer-crosslinker pairs of varied molecular size and revealed a stronger understanding of the relationship between resulting Ψ values and the structures of each monomer-crosslinker pair. In Chapter 4, another mechanistic factor, reactivity ratio between the crosslinker and the main monomer, was also introduced. This chapter studied how both contributions, Ψ and reactivity ratio, influence the eventual crosslinking reaction. All polymerizations were conducted via bulk polymerization in Chapter 3 and Chapter 4. Emulsion polymerization is a heterophase polymerization and their polymers are known as “products by process”. Here, we fed the monomer mixture to the reaction in a semi-batch mode, and therefore, Chapter 5 mainly studied the influence of the monomer feeding profile on gel formation during emulsion polymerization. A relationship was observed that higher feeding rate can cause higher gel content. This was found to be explained by the dominance of a “micro loop” formation, an intramolecular first order reaction between the chain end radical and its own pendent vinyl group, when the unreacted free monomer concentration was very low (i.e. with slow monomer feed rate to the reactor). These microloops consumed pendent vinyls without allowing a crosslinking event to occur. At higher monomer feed rate, the mechanisms xxiii would start to favor the Ψ and reactivity ratio effects again. This was an important learning on the balance between favored mechanisms as a function of the polymerization process and environment. Chapter 6 is a side but still relevant topic. In this chapter, four different bio-based reactive surfactants were successfully synthesized. They could be used as stabilizers for emulsion polymerization. Two of four of reactive surfactants were two different types of bi-functional surfactants (divinyls, thus also considered crosslinkers). They were proved to not only be able to stabilize the particles, but also be able to crosslink the particles under certain conditions. Chapter 6 is a proof-of-concept study and should not be considered completed work. Nonetheless, it shows great promise for continuation by another student.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Mechanical Engineering.
DISSERTATION ABSTRACT:
3D woven carbon/epoxy composites are high-performance materials with superior thermomechanical and physical properties making them an integral part of the aerospace, energy and automotive industries. However, under certain manufacturing conditions, these composites may accumulate severe intrinsic manufacturing-induced residual stresses which can even lead to microcracking. The complex reinforcement architecture makes analytical, numerical and experimental analysis of these composites challenging. This research has been focused on micromechanical analysis, computational modeling, and experimental characterization of 3D woven carbon/epoxy composites aiming to evaluate the manufacturing-induced residual stresses and enable mitigation of their negative impact on the resulting performance. A procedure to develop high-fidelity meso-scale finite element models with as-woven representation of the composite reinforcement informed by the μCT scanning was proposed. A set of meso-scale models for different reinforcement architectures was produced and utilized to predict the accumulation of intrinsic manufacturing-induced residual stresses in these composites. The models were correlated to the blind hole drilling experiments and used for interpretation of the experimental results providing full-field spatial distribution of the residual stresses accumulated in the composite specimens. A new simplified approach to account for nonlinear effects in the material due to severe residual stresses using linearly-elastic models was proposed. A set of parametric numerical studies was performed to improve correlation of the models with the experimental measurements. The developed meso-scale models were used to predict effective coefficients of thermal expansion for the composites with temperature-dependent properties of the constituents. Methods presented in this work provide valuable tools for the field of computational and experimental mechanics of textile composite materials.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Earth and Environmental Sciences.
DISSERTATION ABSTRACT:
Administrative, technical, and financial barriers often prevent sufficient collection of data for stream restoration project evaluation (Roni & Beechie, 2012; Bernhardt et al. 2005; NRC 1992). This lack of evaluation and understanding of restoration impacts can lead to the same misinformed strategies being repeated across restoration sites (Sommerville & Pruitt, 2004). This is particularly relevant for dam management, as the river ecosystem response of dam management strategies, like removal, are not fully understood due to minimal pre-/post-removal studies (Foley et al. 2017; Hart et al. 2002; Poff & Hart, 2002). Stream restoration practitioners need ecological assessment approaches that are affordable, repeatable, objective, and logistically feasible to develop science-based restoration techniques. This dissertation demonstrates how ecological evaluation workflows that use consumer-grade drone imagery coupled with structure-from-motion (SfM) photogrammetry provide an affordable, feasible, adaptable, and flexible solution to many of the challenges facing stream restoration, improving the frequency, accuracy, precision, and coverage of evaluations and improving our knowledge of ecological impacts from restoration practices. The first chapter explores how illustrative drone products (videos, orthomosaics, and 3D models), made using a simple structure-from-motion photogrammetry workflow, can be coupled with a visual stream ecological assessment protocol to provide a remote visual evaluation and ecological condition archive approach. The second chapter explores the intersection of drones, close-range remote sensing, and data science. The work demonstrates how hybrid feature sets derived from the drone RGB orthomosaics and digital surface models can be used to accurately map and quantify riparian vegetation structure via machine learning algorithms for conventional classification tasks that focus on classifying a single site, providing sufficiently accurate results with workflows amenable to use by restoration practitioners. The third chapter demonstrates how drone workflows for mapping and quantifying riparian vegetation structure as well as erosion and deposition throughout fluvial environments can be used to evaluate and monitor changes pre-/post-dam removal, using the Sawyer Mill dam removal project in Dover, NH, USA as a case study. The limitations and efficacies of the drone approaches vs. conventional ecological approaches are compared, and the study demonstrates how the drone approaches leverage the drone’s aerial perspective to provide holistic ecological evaluation data at a landscape scale.
Physical Chemistry Chemical Physics. doi: 10.1039/d1cp00679g
The Journal of Physical Chemistry B. doi: 10.1021/acs.jpcb.0c11096
Computer Methods in Applied Mechanics and Engineering. doi: 10.1016/j.cma.2021.113747
Environmental Development, 37, 100602. doi:10.1016/j.envdev.2020.100602
Materials Science and Engineering: A. doi: 10.1016/j.msea.2021.140980
Sustainability Science doi: 10.1007/s11625-021-00904-3
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science in Hydrology.
THESIS ABSTRACT:
Impounded sediment reduces reservoir storage capacity, which adversely affects dam functionality. For example, reduced capacity limits the ability of flood control dams to mitigate flood peaks, water supply dams to meet demands, and hydropower dams to produce adequate electricity during low flows. Larger sediment volumes also increase the risk of dam failure and increase the logistical complexity of dam removal, an increasingly popular ecosystem restoration method. A model to predict the impounded sediment volume would be useful for decision makers in a watershed or state that need to allocate limited resources to multiple dams. A cross-site comparison among 34 dams was conducted to examine how the volume of impounded sediment was related to sediment supply, transport, and settling. Proxies for sediment supply, transport, and settling were obtained from published datasets and remote sensing. Most methods used to remotely sense proxies were derived from previously published research, but this thesis also developed a novel remote sensing method for locating the position riverbanks. This novel method was found to accurately predict the location of riverbanks in several different river morphologies. Regression analysis was used to quantify relationships between the impounded sediment volume and sediment supply, transport, and settling proxies. Impoundment attributes such as the impoundment surface area, impoundment aspect ratio and dam age were the best predictors of the impounded sediment volume.
Angewandte Chemie International Edition. doi: 10.1002/anie.202017019
Journal of Chemical Theory and Computation. doi: 10.1021/acs.jctc.0c01199
ASME 2020 International Mechanical Engineering Congress and Exposition. doi: 10.1115/imece2020-24111
Journal of Materials Science & Technology, doi: 10.1016/j.jmst.2020.12.047
Proceedings of the ASME 2020 15th International Manufacturing Science and Engineering Conference. Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability. September 3, 2020. V002T08A012. ASME. doi:10.1115/MSEC2020-8372
Biophysical Journal, doi: 10.1016/j.bpj.2020.12.010
Journal of Micro and Nano-Manufacturing, doi: 10.1115/1.4049364
Journal of the American Chemical Society, doi: 10.1021/jacs.0c07041
Mechanics of Materials, 154, 103707. doi: 10.1016/j.mechmat.2020.103707
Submitted to the University of Maine in Partial Fulfillment of the Requirements for the Degree of Master of Science in Wildlife Ecology and Wildlife Conservation.
THESIS ABSTRACT:
After beginning life in the Sargasso Sea, American eel enter river systems as juveniles and swim upstream in pursuit of freshwater habitat. Many encounter dams during this migration which act as barriers to upstream movement and limit eel establishment in headwater systems. Some dams have been retrofitted with fishways to improve watershed connectivity, but the individual selection imposed by these structures remains uncharacterized. We considered whether individual differences in behavior (i.e., personality) may be used to predict the propensity of juveniles to use a passage structure, suggesting that eel personality may predict access to habitat upstream of dams. Migrating, juvenile eels (n=63) were captured from a tidal tributary, and we measured the expression of bold and exploratory behaviors in classic animal personality assays (open field and emergence). Then we assessed the propensity for individuals to volitionally climb through a passage structure and assessed passage outcomes. Finally, we compared consistent behavioral tendencies and climbing propensity.
We show evidence for personality in young eels by demonstrating among-individual variation in bold and exploratory behaviors that were consistent across repeated trials in open field and emergence assays. Mean swimming speed in the open field was a predictor of climbing propensity; faster fish were less likely to climb through a passage structure. For successful climbers, climbing time was negatively associated with fish length, offering evidence for potential size-based selection on climbing ability during upstream passage at dams. Our results suggest strong potential for selective pressure on both climbing motivation and ability during fish passage Preventing a subset of individuals from accessing upstream habitat may have unintended consequences for both aquatic ecosystems and American eel populations.
Eels that successfully recruit to habitat upstream of dams may spend decades in freshwater systems before making a single, terminal migration to spawn in the Sargasso Sea. Therefore, individuals that ascended dams as juvenile, must navigate these same dams while moving downstream as mature adults, where passage is commonly associated with mortality and delay. We conducted a four-year acoustic telemetry study that characterized passage risks through two hydropower dams (West Enfield and Milford) in the Penobscot River, Maine, USA. We released tagged fish (n=355) at two sites, estimated survival and delay under variable river conditions, and compared performance among dammed and free-flowing river sections. Survival rates (standardized per river km) were lower at West Enfield (Φrkm = 0.984 ± 0.006 SE) and Milford (Φrkm = 0.966 ± 0.007 SE), compared to undammed River sections (Φrkm = 0.998 ± 0.0003 SE). This accounted for 8.7%, 14.2%, and 8.7% cumulative mortality through sections classified as West Enfield (4.4km), Milford (5.5km), or River (58.1km) respectively. Fish that already passed an upstream dam incurred higher downstream mortality compared to individuals without passage experience. Additionally, fish endured long delays at dams, and >10% of fish were delayed >24h. Low flows exacerbated the risk of mortality and delay. These results offer evidence for direct, latent, and sub-lethal consequences of dam passage for migrating eels.
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2514738140
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2490074300
ACS Macro Letters, 9, 1836-1843. doi: 10.1021/acsmacrolett.0c00774
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Civil and Environmental Engineering.
DISSERTATION ABSTRACT:
Floods lead to the overtopping of dams which is the main cause of dam failures and can result in significant loss of lives and property. This study investigates how the hydrological failure probability of dams in New England may change with future changes in climate and land use. Non-stationarity of future precipitation caused by the anthropogenic climate change and altered watershed concentration times caused by anthropogenic alterations such as urbanization, industrialization or deforestation can impact the mechanisms of runoff production and transfer. This can potentially change the frequency, magnitude, or duration of floods. Therefore, due to different flood patterns and consequently different hydrological failure probability, dams in New England likely have very different future risk levels. As hydrological failure probability indicators, the magnitude and frequency, and duration of floods exceeding a threshold are used to determine the variability of hydrological failure probability. Aside from the historical measured and gridded climate and land use data, this study uses one high temporal- and spatial-resolution, dynamically downscaled climate change projection and 29 statistically downscaled climate change projections as well as four land use projections from “The New England Landscape Futures Project”. Results show that basin response in New England during high-flow events has not significantly changed during recent decades in spite of recent changes in climate and runoff generation mechanisms. Also, dammed basins with higher storage capacity are found to have a decrease in basin response and flood peaks while there is not enough evidence the significance of urban development on high-flow events in New England. It is likely that dams in New England experience higher levels of hydrological failure probability. This is because compared to historical data, future floods are likely to increase in magnitude and frequency, but they are not likely to last longer. Also, the results show more accentuated increase in the frequency compared to the magnitude of future floods. This study will help dam owners and state regulators plan for more resilient dam operations and more rigorous dam maintenance and account for the future risk associated with the approximately 15,000 dams in New England.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering.
THESIS ABSTRACT:
Results for SS316L microtube experiments under combined inflation and axial loading for single and multi-loading segment deformation paths are presented along with a plasticity model to predict the associated stress and strain paths. The microtube inflation/tension machine, utilized for these experiments, creates biaxial stress states by applying axial tension or compression and internal pressure simultaneously. Two types of loading paths are considered in this paper, proportional (where a single loading path with a given axial:hoop stress ratio is followed) and corner (where an initial pure loading segment, i.e., axial or hoop, is followed by a secondary loading segment in the transverse direction, i.e., either hoop or axial, respectively). The experiments are designed to produce the same final strain state under different deformation paths, resulting in different final stress states. This difference in stress state can affect the material properties of the final part, which can be varied for the intended application, e.g., biomedical hardware, while maintaining the desired geometry. The experiments are replicated in a reasonable way by a material model that combines the Hill 1948 anisotropic yield function and the Hockett-Sherby hardening law. Discussion of the ix grain size effects during microforming impacting the ability to achieve consistent deformation path results is included.
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering.
THESIS ABSTRACT:
This work presents improvements to the methods used in crystal plasticity simulations. It shows how these improvements can be used to accurately predict the deformation behavior of two magnesium alloys, WE43, and AZ31. The first improvement to the methodology is guidance on the type of finite elements to use in explicit grain crystal plasticity simulations. This study found that quadratic tetrahedral and linear hexahedral elements are the most accurate element types included in the study. The study also concluded that tetrahedral elements are more desirable due to fast mesh generation and flexibility to describe geometries of grain structures. The second improvement made was the addition of a numerical scheme to enable the use of any rate sensitivity exponent in the fundamental power-law representation of the flow rule in crystal visco-plasticity. While allowing the use of even very large exponents that many materials exhibit, this numerical scheme adds little to no increase in computational time. This crystal plasticity model was used to accurately predict the deformation behavior of both WE43 and AZ31 under quasi-static and high rate deformation, predicting the stress-stain response and the evolution of texture, twinning and the relative activities of the various deformation modes.
Journal of Materials Chemistry B, doi: 10.1039/d0tb02475a
Elementa: Science of the Anthropocene, 8(1). doi:10.1525/elementa.003
Energy Policy, 143, 111457. doi:10.1016/j.enpol.2020.111457
Materials Science and Engineering: A. doi: 10.1016/j.msea.2020.140478
Environmental Research Letters, 15(10), 104054. doi:10.1088/1748-9326/abad58
Journal of Molecular Biology. doi: 10.1016/j.jmb.2020.08.026
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2445953572
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master in Science in Natural Resources: Environmental Conservation.
THESIS ABSTRACT:
New Hampshire’s aquatic resources provide many important ecosystem services and values, such as recreation, wildlife habitat, flood storage, nutrient reduction, community identity and aesthetic enjoyment. However, the many competing interests that seek to benefit from New Hampshire’s aquatic resources present challenges for efforts to steward public aquatic resources in the public interest. This thesis presents findings about the environmental justice outcomes of New Hampshire’s compensatory mitigation program, the Aquatic Resource Mitigation (ARM) fund, to inform aquatic restoration policy.
Previous studies have found evidence that aquatic restoration programs can lead to systemic resource relocation and patterns of inequality in outcomes. Using geospatial and statistical analyses, this research compares census-tract level socioeconomic data on specific demographic characteristics (minority population, low education, population density and income) with the spatial location of New Hampshire compensatory mitigation program sites. Census tracts are analyzed according to groupings at the state level and for two service areas with different population densities: the Merrimack and Middle Connecticut Service Areas. This research also applies a geospatial approach to recommend areas where outreach could be expanded to increase environmental justice communities’ participation in the ARM fund.
Consistent with previous compensatory mitigation and environmental justice literature, this research finds demographic characteristics are an important consideration for environmental justice. At the statewide census-tract level, I find that populations around mitigation sites are more likely to have a lower percentage of nonwhite populations, lower population density, and higher income, as compared to sites without mitigation sites. Populations around permit sites are also likely to have lower population densities. I also find that this level of analysis is important to recognize inequalities and inform natural resource management decisions. In contrast, to the statewide results, I find significant demographic differences within the relatively low population density Middle Connecticut region. For the Merrimack region, which is larger and more diverse, results are similar to the statewide analysis: I find that populations around mitigation sites are more likely to have a lower percentage of nonwhite populations. Unlike the statewide analysis, I find that populations around mitigation sites are more likely to have lower educational attainment and populations around permit sites are more likely to have higher incomes.
Then, I identified 26 environmental justice communities with aquatic restoration opportunities and found that almost half of these communities have participated in the ARM fund by submitting proposals to receive mitigation funding. Using an optimizing hot spot analysis and a heat map, I identified three environmental justice communities that have experienced significant wetland loss and to which the ARM Fund could target outreach: Manchester, Dover and Newington.
This thesis research is intended to provide guidance to state agencies, cities and towns, nongovernmental organizations, and others interested in advancing protection of New Hampshire’s aquatic resources. The analytic methods contribute to broader research into the human dimensions of water policy.
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2445435236
Soft Matter, 16, 8101-8107. doi: 10.1039/d0sm00954g
Entropy, 22(8), 877. doi:10.3390/e22080877
International Journal of Plasticity, 136, 102807. doi: 10.1016/j.ijplas.2020.102807
Chemistry of Materials. doi: 10.1021/acs.chemmater.0c01007
Nano Research. doi: 10.1007/s12274-020-2874-x
Restoration Ecology. doi:10.1111/rec.13228
Resources, Conservation and Recycling, 161, 104990. doi:10.1016/j.resconrec.2020.104990
UNH Scholars Repository (Carsey School of Public Policy)
The Journal of Physical Chemistry Letters. doi:10.1021/acs.jpclett.0c01390
Chemistry of Materials. doi: 10.1021/acs.chemmater.9b05289
Memorandum prepared for the U. S. Fish and Wildlife Service, Coastal and Partners Program. Brett Still and Art Gold facilitated URI support for this publication and 7 Future of Dams graduate students were recognized for their assistance with field work, data management and processing, and GIS mapping.
Acta Materialia, 195, 59-70. doi: 10.1016/j.actamat.2020.04.036
Submitted to the University of Maine in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Ecology and Environmental Sciences.
DISSERTATION ABSTRACT:
The Federal Energy Regulatory Commission (FERC) is the regulatory body that oversees non-federally owned dam operations in the United States. With more than 300 hydropower dams across the U.S. seeking FERC relicense between 2020 and 2029, and 135 of those dams within the Northeast region alone, it is prudent to anticipate and plan for such decision-making processes. Anyone may be involved in FERC relicensing; in fact, FERC solicits public comment and requires the licensee to hold a public hearing during the process. Parties may also elect to apply for legal intervenor status, allowing them a more formal entry into the relicensing process. However, there are two key barriers that may keep the public from participating in a dam decision-making process in an impactful way. The first of these barriers is access to information. Having access to the types of information that matters to FERC is important, because it allows the participant to communicate their support or concerns about the relicensing using the language of the process. In particular, participants other than the licensee may not have access to project economic information, so this is a focus in my research. The second barrier is capacity to participate in a way that impacts the process (i.e., institutional knowledge about what kinds of decision criteria (factors) and decision alternatives (project options), as well as relevant data, that FERC typically weighs in their decision making or has considered in the past). Actors not privy to license information (perhaps encountering difficulty in navigating the FERC eLibrary), lacking knowledge of FERC process conventions, or otherwise unfamiliar with hydropower dam schemes or operations have substantial hurdles preventing their effective participation. My research, situated in the sustainability science arena, addresses hydropower project cost and performance assessment and multi-criteria considerations for dam decision support. I lead the development and assessment of an online Dam Decision Support Tool aimed at addressing barriers to the hydropower dam decision-making process. My work demonstrates possibilities for tailoring decision tools to incorporate stakeholder perspectives into decision making about hydropower dams.
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2439345330
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2444866135
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Civil and Environmental Engineering .
DISSERTATION ABSTRACT:
Dam decision-making is often controversial as a choice has to be made between the benefits provided by dams (e.g., recreation, water supply, hydropower) and their potential negative impacts (e.g., effects on natural flow regime, impediment for fish migration). However, our understandings of such tradeoffs under a full range of dam management alternatives remain limited which hinders our ability to make sound and scientifically defensible dam management decisions. The diverse stakeholders involved in the decision-making process with varying perspectives and preferences could further exacerbate the difficulty of decision-making. To advance our knowledge in sustainable dam decision-making, this dissertation developed modeling tools to evaluate dam decisions based on greenhouse gas (GHG) emissions, hydropower generation, sea-run fish population, and management cost from both spatial and temporal perspectives. The developed model was further applied in role-paly simulation workshops to investigate the potential differences between scientifically optimized decisions and the negotiated consensus. The results revealed that although most hydroelectric dams have comparable GHG emissions to other types of renewable energy (e.g., solar, wind energy), electricity produced from tropical reservoir-based dams could potentially have a higher emission rate than fossil-based electricity. It is possible to simultaneously optimize energy, fish, and cost outcomes through strategic dam management actions. Basin-scale management strategies may outperform individual dam management strategies because the former can provide a broader set of solutions for balancing complex tradeoffs than the latter. Furthermore, diversification of management options (e.g., combination of fishway installations, dam removals, and generation capacity) may have the highest potential in balancing fish-energy-cost tradeoffs. Finally, dam management negotiation is helpful in facilitating decisions with more balanced outcomes but not necessary reflect the environmentally optimal outcomes.
Submitted to the University of New Hampshire In Partial Fulfillment of the Requirements for the Degree of Master of Science In Chemistry May 2020.
THESIS ABSTRACT:
This thesis explores the use of Diels-Alder functionalized particles to aide in the mechanical enhancement of additively manufactured objects. To date, materials generated via additive manufacturing lack isotropic properties due to the nature in which they are created – in a layer by layer fashion. This methodology often leads to poor interfacial adhesion at the junction between printed layers, lowering the stability of the part and thereby limiting its use in many applications. Dynamic covalent chemistry, such as the reversible Diels-Alder reaction, has the ability to alleviate this anisotropy to print stronger, more uniform objects. To do so, this work investigates crosslinked, Diels-Alder functionalized particles generated by two separate methods: polymerization via reversible addition fragmentation chain transfer (RAFT) followed by atom transfer radical coupling (ATRC) and free radical emulsion polymerization. These particles can be blended with a polymeric filament for 3D printing, where upon heating during the extrusion process of additive manufacturing, the retro-Diels-Alder reaction is initiated and releases the crosslinked particles exposing reactive diene and dienophile pairs. In subsequent xvii cooling after the printing process, these moieties undergo the forward Diels-Alder reaction and form chemical linkages between printed layers of the substrate to improve the mechanical integrity and uniformity of objects produced by means of additive manufacturing.
Submitted to the University of Rhode Island in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Environmental & Natural Resources Economics.
DISSERTATION ABSTRACT:
Many dams throughout New England are approaching the end of their engineered lifespan. Individual dam owners and governments at various levels find themselves navigating decisions to repair, remove, or modify the aging infrastructure. These decisions have implications for the ecosystem services that depend on the presence or absence of dams. By coordinating the ecosystem service tradeoffs at large scales we can more efficiently utilize the productive capacity of river systems. Implementing a large-scale coordinated approach, however, requires understanding stakeholder preferences at different scales, and the willingness of decision makers to coordinate (or not). In this dissertation I address issues surrounding a coordinated approach to ecosystem service provision with the goal of facilitating better decisions. In the first chapter, I administer a choice experiment survey to study how environmental risk preferences interact with scale to determine willingness to pay for ecosystem services from dam removal. Improved understanding of scale-dependent preferences can allow nonmarket valuation estimates for ecosystem services to integrate more smoothly into decisions at a variety of scales. In the second chapter, I explore environmental federalism in dam removal decisions (i.e., whether state goals diverge from larger-scale optimization). I use matching and instrumental variable techniques to model the determinants of dam removal using a large, spatially explicit dataset. Results suggest that states consider border proximity when selecting dams for removal, indicating a need for new incentive structures to realize efficiency gains from coordination. In the final chapter, I study how a production possibilities model can be combined with public preference data from a choice experiment, expressed as indifference curves, to identify socially preferred ecosystem service outcomes from dam removal. I find that the approach is useful for pinpointing areas of agreement and disagreement between stakeholder groups with varying preferences.
UNH Scholars Repository https://scholars.unh.edu/cgi/viewcontent.cgi?article=1012
Submitted to the University of Maine in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Communication.
DISSERTATION ABSTRACT:
How do we understand what to do with rivers and dams? How might rhetoric, the ancient study of persuasion, inform and shape this understanding as it relates to river restoration practices? Ecological approaches to rhetoric provide ways for engaging in decision making about dams and river restoration. In this dissertation I present three projects that bring media discourse analysis, reciprocal case study, and cross-cultural digital rhetoric to sites of collaborative decision making about dams and rivers in the Penobscot River watershed (Maine, USA). In this place, the prominent Penobscot River Restoration reconfigured several hydroelectric dams to improve fish passage and hydropower generation. My collaborators and I explore what needs and opportunities remain for further action here and how community-engaged rhetorical ecology can advance decolonization and social-environmental justice.
In the first project, we ask how news media about dams portray river restoration and how these portrayals matter for ongoing collaboration and decision making. We use a rhetorical approach within transdisciplinary media discourse analysis to explore 30 years of newspaper coverage of dam removal, with particular focus on news media about the Penobscot Restoration. Our results show that news media have widely framed the project as a success based on technical and social outcomes and that this framing limits what we can understand about the complexities of restoration and ongoing needs that remain on this river. In this way, media analysis can reveal opportunities for further collaborative engagement.
In the second project, we build on the first to ask about other histories, futures, and stories that are left out of the dominant Penobscot Restoration success narrative. We advance an ethnographic case study approach where engaging across communities presents opportunities for changing how we do research. Doing research with community partners shifted our study from a retrospective focus to a focus on reciprocation--from looking back on past restoration activity to using research as a way of giving back to those who made the work possible. The results show how building relationships and opening up our research processes to this kind of reordering helps expand understandings of what we can work to restore.
In the third project, we explore where reciprocation can lead when advancing research projects in response to our partners' needs. We ask how digital approaches shape the opportunities for collaboratively composing alternative forms of media documentation for decolonization. In our analysis, we reflect on developing procedural digital ethics to support visual portrayals of Indigenous environmental science as a form of ongoing restoration practice. Our results show how this process relies on relationship building, cross-cultural dialogue, and flexible naming practices that reshape how we can collectively see our histories and work together toward socio-environmental justice.
ProQuest Dissertation or Thesis https://www.proquest.com/docview/2434061589
Submitted to the Faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Since the discovery of electrically conductive two-dimensional (2D) metal–organic frameworks (MOFs), the synthetically tunable properties and intrinsic porosity of these materials make them promising for multifunctional sensing devices. The focus of my work is on a class of 2D MOFs based on a triphenylene core (2,3,6,7,10,11- hexahydroxytriphenylene, HHTP and 2,3,6,7,10,11-hexaiminotriphenylene, HITP) coordinating to divalent Cu or Ni metal nodes forming M3HXTP2 MOF analogs (M = Ni, Cu; X = NH, HITP or O, HHTP). Chapter 2 describes a simple strategy for device fabrication, using mechanical abrasion, enabling the chemiresistive sensing of NH3, H2S, and NO. The value in this contribution is threefold. First, the technique may be applicable to a wide range of materials, both semiconductors and possibly insulators. Second, the rapid prototyping method enables direct deposition using mechanical abrasion on a wide range of substrates. Third, the integration of the MOF-based sensing material into devices is entirely solvent-free, which can preserve device substrates sensitive to harsh solvents. Chapter 3 describes a new strategy of MOF synthesis termed oxidative restructuring that feature several innovative characteristics that advance the field of MOF integration. First, oxidative restructuring enables the facile integration of Cu3HHTP2 and Cu-BTC onto prepatterned Cu layer on multiple substrates. Second, we detail spectroscopic evidence that provides insight into the interaction between Cu3HHTP2 and NO using diffuse reflectance infrared fourier transform spectroscopy and X-ray photoelectron spectroscopy. Third, Cu3HHTP2 MOF devices demonstrated the highest dynamic loading capacity of NO and functioned as chemiresistive sensors for the detection of NO and H2S. Chapter 4 describes the implementation of 2D MOF based electrodes to enable the voltammetric detection of biologically relevant analytes. First, strategic selection of redox active analytes combined with the electrochemical methods, allowed us to investigate the intrinsic electrochemical properties of M3HXTP2 MOF analogs (M = Ni, Cu; X = NH, HITP or O, HHTP). Second, this demonstrated one of the first uses of 2D MOFs in solution phase detection with nanomolar detection at 63 ± 11 nM for dopamine and 40 ± 17 nM for serotonin. Taken together, chapters 1-4 advance the field of conductive metal–organic frameworks by providing insight in molecular engineering of MOFs that guides the iii structure property relationships to enable precise function for chemical detection and provides strategies for the strategic integration of MOFs on substrates.
River Research & Applications. doi: 10.1002/rra.3616
Journal of the American Chemical Society. doi: 10.1021/jacs.9b13402
PLOS ONE, 15(3), e0229501. doi:10.1371/journal.pone.0229501
Chemistry of Materials. doi: 10.1021/acs.chemmater.9b04092
Authorea doi: 10.1002/essoar.10502249.1
Poroi, 12(1). doi:10.13008/2151-2957.1302
Environmental Sociology, 1–13. doi:10.1080/23251042.2019.1696008
Submitted to the University of Maine in Partial Fulfillment of the Requirements for the Degree of Master of Science in Wildlife Ecology and Wildlife Conservation.
THESIS ABSTRACT:
Hydropower dams represent a significant challenge for the successful migration of sea-run fish, many species of which are in decline. Most hydropower dams in the United States are regulated by the Federal Energy Regulatory Commission (FERC), an independent federal agency responsible for granting 30 to 50-year licenses to projects for their continued operation. Licenses typically include conditions for the conservation of sea-run fish such as fish passage construction, operational changes, monitoring of effectiveness, and other mitigative conditions. While FERC remains the primary authority in licensing, the current regulatory framework stipulates input from other federal and state resource and regulatory agencies, many working from differing timeframes, varying levels of authority, and within the bounds of a complex legal system.
Outside of the relicensing process, modifications and improvements are not required unless prescribed in the original license or prompted by legal action (e.g., the listing of new species under the ESA). In effect, the relicensing process presents the most effective opportunity for agencies to influence dam operations. Due to accelerated construction of hydropower dams in the 1980s, many of the projects in Maine will require relicensing within the next decade requiring input from an array of federal and state agencies. When negotiating hydropower operations, agencies must make timely decisions and examine tradeoffs based on their respective and often competing authorities, values, and objectives. Using the Kennebec and Penobscot Rivers in Maine as a model system, the overall goal of this research is to examine the hydropower relicensing process to: 1) identify and describe the role and authority of resource agencies during dam relicensing, 2) determine the factors that may affect the design and implementation of fish passage measures, and 3) highlight management and policy implications that may be used to inform fish passage decisions and future relicensing efforts. This research provides the historical context for fish passage in the study area and describes hydropower regulation.
The first chapter uses content analysis of relicensing documents readily available on the Federal Energy Regulatory Commission (FERC) eLibrary to identify the main factors that influence fish passage decision-making and describe patterns in agency engagement during relicensing. Our results indicate an overall increase in concern for fish passage over time with mitigation measures focused almost exclusively on Atlantic salmon and American eel. Agency engagement and the use of regulatory authority increased after the 1900s, especially with regards to the use of Water Quality Certification conditions as a tool for addressing fish passage. Overall, hydropower projects were found to differ along a spatial gradient with coastal projects correlated strongly to fish passage language and input from the Maine Department of Marine Resources (MDMR), United States Fish and Wildlife Service (USFWS), and National Oceanic and Atmospheric Administration (NOAA) and inland projects to input from the Maine Department of Inland Fisheries and Wildlife (MDIFW). Despite stated interest in basin-scale planning, policies in support of it, and continued improvement, implementation has been slow at best. Our results suggest there remain significant opportunities to spatially integrate the FERC process.
The second chapter investigates the concept of “best available science” (BAS) as it applies to the relicensing decision process. Agency regulators are tasked with using the BAS to make informed decisions about hydropower operations and management. Although embraced as the standard, best available science is not well-defined and is inconsistently applied. Citation analysis and an online survey of regulatory and resource agency staff were used to identify the informational sources used in relicensing and assess agency perceptions of BAS. Analysis of relicensing documents (n=62) demonstrates that FERC and licensee documents (i.e., documents produced by the individual or organization that was granted the license) are highly similar in citation composition. NOAA reports typically cite more sources and are three times more likely to cite peer-reviewed literature than FERC and licensee documents. Survey data reveals that federal and state agency respondents (n=49) rate peer-reviewed literature highly in terms of BAS, followed by university (e.g., theses), agency (e.g., agency grey literature), and expert sources (e.g., guidance from experts), while industry (e.g., consultant reports) and community (e.g., comments and personal interactions) sources rate poorly. Overall, there is low agreement among respondents with regards to BAS rankings of informational sources. The reported differences in information use may be linked to disparities in access to certain sources, particularly peer-reviewed literature. A common concern expressed by agency staff is the lack of applied technical information for all aspects of dam operations.
One such disparity relates to the difficulty in assessing downstream passage for out-migrating juvenile fish. The final chapter addresses this knowledge gap by describing the development of a novel buoyancy conversion (BC) tag that may be used to facilitate fish recapture for passage assessments. The BC tag uses low-cost materials, does not significantly hinder fish movement, and has a delayed deployment. This chapter provides a detailed description of the BC tag and describes the process used to optimize the tag for a range of fish sizes, specifically for juvenile river herring. This work is intended for the public domain and is meant to be highly adaptable for use with many fish species and life stages.
Soft Matter. doi:10.1039/c9sm01878f
Submitted to the University of Maine in Partial Fulfillment of the Requirements for the Degree of Master of Science in Ecology and Environmental Sciences.
DISSERTATION ABSTRACT:
The term governance has undergone somewhat of an evolution since its inception, originally describing the act of governing, it has come to represent a more collaborative form of governing which is distinct from hierarchical control models (Marin and Mayntz, 1991). Collaborative governance refers to the systems associated with public policy decision making and resource management which span the jurisdictional boundaries of public agencies, levels of government, and/or public and private spheres in order to pursue a public policy goal or outcome (Emerson et al., 2012). Environmental management is often considered an inherently collaborative effort, as ecological systems and species rarely fall neatly within political or other human constructed boundaries (Bodin, 2017a).
Collaborative environmental governance systems can be a response to joint-jurisdictional management, where multiple managing organizations have legal jurisdiction over a species or system. This is often the case with species listed under the United States Endangered Species Act (ESA). Collaborations can also aid in dealing with the challenges of operating in a resource limited world. By forming collaborative governance structures, organizations aim to leverage resources, expand knowledge of the system, and avoid working at cross-purposes (Emerson and Nabatchi, 2015; Ulibarri and Scott, 2017). Whatever the original motivator, there are practical challenges associated with implementing a collaborative governance structure, and the success with which these structures operate varies greatly (Emerson et al., 2012).
Using the Atlantic Salmon Recovery Framework (ASRF) as a mixed-methods case study, we aim to further our understanding of communication, collaboration, institutional capacity for change, and barriers and opportunities for collaboration through Communication Network Analysis (CNA) and semi-structured interviews with members of the ASRF. The Gulf of Maine (GOM) Distinct Population Segment of Atlantic salmon (DPS) is managed by the National Oceanic and Atmospheric Administration (NOAA) the United States Fish and Wildlife Service (USFWS), the Maine Department of Marine Resources (MDMR), and the Penobscot Nation (PN). Individuals from these four organizations make up the ASRF, the current governance structure for Atlantic salmon management and recovery in the state of Maine.
In chapter 2, we describe the theoretical frameworks, methods, results, and significant implications of the CNA we conducted. 95% (N=41) of the individuals identified as members of the ASRF (N=43) participated in an online sociometric survey. The sociometric survey asked participants about their position within their organization and the ASRF, how long they have worked in Atlantic salmon management and/or recovery, the frequency with which they communicate with other members of the ASRF, and the productivity of those communications, using open and close-ended questions. In chapter 3, we describe the theoretical frameworks, methods, results, and significant implication of the semi-structured interviews we conducted. 68% (N=28) of individuals who were invited (N=41), participated in a semi-structured interview. The semi-structured interviews focused on member perceptions of ASRF operations, procedures, strengths, weaknesses, and power dynamics.
The CNA reveled that there is relatively high network density for individual communication (56%), but that connections are decentralized, a characteristic that can be incompatible with some organizational structures. Challenges reported by members fit into three general categories; 1. slow and ineffective decision-making, 2. confusion surrounding leadership and accountability, and 3. low adaptive capacity. The semi-structured interviews suggest that the lack of integration across organizations could be due in part to members reporting issues associated with leadership, operational transparency, lack of trust, and perceived differences in management styles and objectives. The lack of leadership was evident in both the CNA and interview data. As the managing organizations work to restructure the ASRF, the results and recommendations provided in this thesis have served as a valuable tool in identifying strengths, weaknesses, institutional barriers, and capacity of change.
Environmental Communication, 14(3), 416–429. doi:10.1080/17524032.2019.1686408
In Developing Change Agents Edited by Kristi L. Kremers, Alexander S. Liepins, and Abigail M. York. EBOOK ISBN: 978-1-946135-57-5
Polymer Chemistry. doi:10.1039/c9py01510h
Stochastic Environmental Research and Risk Assessment. doi: 10.1007/s00477-019-01726-7
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering September, 2019.
THESIS ABSTRACT:
The following research explores the continuous bending under tension (CBT) incremental forming process effects on four dual phase (DP) steels: DP 590, DP 780, DP 980, DP 1180. A parameter study was conducted, finding the ideal parameters for increased elongation to fracture compared to tension of over five times for DP 1180 and DP 980. These parameters were found to be a normalized bend depth of 3.5 and a crosshead pull speed of 1.35mm/s. Using these parameters, following tests were conducted on all four steels by stopping the CBT process before fracture at 2, 4, 6, 8, and some even at 10 and 12 CBT cycles. Smaller tensile specimens were machine from these CBT processed strips and uniaxial tension tests were performed to study the residual ductility of CBT testing. The strength of all steels increased with increased cycle count by 200-400 MPa, however the ductility decreased by over half. Using neutron diffraction, the texture evolution of the CBT process was explored. Results showed a preferred orientation in the {011} fiber in the pulling direction. This research also proves simulating the CBT process and matching to experimental data can be a method for extrapolating post-necking hardening behavior of DP 980 and DP 1180. The experimental data and results are further explained in the following chapters.
Physical Chemistry Chemical Physics, 2019. doi: 10.1039/c9cp04408f
Nat Sustain 2, 647–649 (2019) doi:10.1038/s41893-019-0357-4
Many of New Hampshire’s dams are reaching the end of their lifespan and require expensive maintenance or removal in order to meet safety standards. While engineers and public officials struggle with the scale of the challenge surrounding various dam management alternatives, including removal, what does the New Hampshire public think? In this brief, authors Natallia Leuchanka, Catherine Ashcraft, Kevin Gardner, and Lawrence Hamilton present results from statewide surveys in New Hampshire that explore public views about dam removal. They report that a majority of respondents in three Granite State Polls prefer to remove dams when the alternative is to keep them for maintenance of waterfront property values, preservation of industrial history, or maintenance of lake- and pond-based recreation. A majority of survey respondents prefer to keep dams when dams are for hydropower generation. Respondents’ age, gender, and party affiliation often predict their preference for dam removal. Levels of formal education do not make much difference. Younger respondents, women, and Democrats are more likely to support dam removal, although this varies somewhat depending on the tradeoffs.
North American Journal of Fisheries Management, 39(5), 989–998. doi:10.1002/nafm.10330
Molecular Simulation, 45(14-15), 1273–1284. doi: 10.1080/08927022.2019.1634268
Journal of the American Chemical Society 2019 141 (30), 11929-11937. doi: 10.1021/jacs.9b03441
Science of The Total Environment, 669, 833–843. doi: 10.1016/j.scitotenv.2019.03.042
Sustainability Science. doi:10.1007/s11625-019-00707-7
International Journal of Solids and Structures, 174-175, 28–37. doi: 10.1016/j.ijsolstr.2019.06.005
Chemistry – A European Journal, 25(46), 10768–10781. doi: 10.1002/chem.201900975
This dissertation has been examined and approved in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry.
DISSERTATION ABSTRACT:
Atom transfer radical coupling (ATRC) is gaining recognition for its utility in building complex polymeric architectures because it features efficiency, a wide range of compatible substrates, and a lack of byproducts. These qualities are especially desirable in applications requiring intramolecular cross-linking as in the synthesis single-chain nanoparticles (SCNP). This dissertation aims to (I) provide motivation and context for developing ATRC technology for intramolecular cross-linking, (II) provide guidance into the impact of catalyst selection and substrate on reaction efficiency and morphology, and (III) demonstrate the possibility to sequence intrachain ATRC with ATRP to create advanced SCNP architectures. Chapter II describes the preparation of SCNP from parent polymers containing alkyl or benzyl bromide ester pendants using ATRC catalyzed by copper halides complexes. Tri- or tetradentate alkyl or pyridyl amines (PMDETA, TPEN, and TPMA), which tune the redox potential of the Cu(I)/Cu(II) system, were directly compared. Coupling efficiency was positively correlated with the kATRP of the respective catalyst systems. However, PMDETA complexes afforded greater control as evidenced by lower polydispersity. In the case of alkyl halide pendants, selectivity for coupling over disproportionation systematically decreased under conditions designed to increase the concentration of CuI /L. Polymers with benzyl bromide pendants, which cannot disproportionate, tended to produce high molecular weight products, even in ultradilute solutions (0.25 –1.0 mg/mL). xvii Chapter III describes the preparation of SCNP from parent polymers capable of initiating intra-chain polymerization by ATRP under conditions favoring termination by coupling. Because of the wide variety of compatible monomers that have been well-established for ATRP systems, the ATRP/C framework both simplifies reaction procedures (one pot polymerization and coupling strategies are feasible) and imparts handles with which to control both architecture and functionality. To demonstrate this potential, model simple brushes and hyperbranched examples were prepared. SCNP with the hyperbranched motif were remarkably dense, a result which demonstrates the potential to facilitate more globular SCNP structures using modifications of intrachain polymerizations. Methacrylic brush arms, which are not non-ATRC active, could be induced to couple by adding 5 equivalents of styrene under the shared ATRP/C conditions. In addition, it was determined that hyperbranched SCNP retain “living” ω-ends which may be initiated to perform post-collapse polymerizations. A model styrene example is presented; despite occurring in an ultradilute solution, the polymerization maintains fidelity to pseudo-first order kinetics. In sum, there is currently a great impetus for pushing the boundaries of structural and functional complexity that can be designed using the single-chain nanoparticle motif. Atom transfer radical chemistry is a particularly versatile example and it is my hope that this work facilitates the creation of new creative and functional designs.
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Marine and Coastal Fisheries, 10(2), 236–254. doi: 10.1002/mcf2.10021
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Carsey Research National Fact Sheet, Carsey School of Public Policy, University of New Hampshire. National Fact Sheet No. 37
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Oxford Research Encyclopedia of Climate Science. doi: 10.1093/acrefore/9780190228620.013.442.
Resilience 2017 Conference Proceedings. Stockholm Waterfront Congress Centre, Sweden, August 20-23, 2017.
Resilience 2017 Conference Proceedings. Stockholm Waterfront Congress Centre, Sweden, August 20-23, 2017.
Geosciences, 7(3), 54. doi: 10.3390/geosciences7030054
Conference proceedings from the Association of Environmental Engineers and Science Professors (AEESP) Research and Education Conference, University of Michigan, Ann Arbor, Michigan, June 21-22, 2017.
Carsey Research Policy Brief, Carsey School of Public Policy, University of New Hampshire. National Issue Brief No. 123
Ecology and Society, 22(2), 39. doi: 10.5751/es-09105-220239. Part of a special feature on Ecosystems and Society: Interactions Among Climate, Land Use, Ecosystem Services, and Society.
Society and Natural Resources, 1–16. doi:10.1080/08941920.2017.1315653
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Oxford Research Encyclopedia of Climate Science. doi: 10.1093/acrefore/9780190228620.013.563.
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Carsey Research National Fact Sheet, Carsey School of Public Policy, University of New Hampshire. National Fact Sheet No. 35.
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Technical report summarizing research findings.
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Carsey Research Policy Brief, Carsey School of Public Policy, University of New Hampshire. Regional Issue Brief No. 45
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Great Bay Matters, Spring/Summer 2015
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Reflections: A Journal of Public Rhetoric, Civic Writing, and Service Learning, 16(1), 75-95
Technical report provided to the Campus Compact and Campuses for Environmental Stewardship program
Technical Report. Luc Hoffmann Institute, Pew Charitable Trusts, California Ocean Science Trust, Science and Resilience Institute at Jamaica
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M.S. Dissertation, Department of Natural Resources & the Environment, College of Life Science and Agriculture, University of New Hampshire, Durham, NH
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M.S. Dissertation, Department of Natural Resources & the Environment, College of Life Science and Agriculture, University of New Hampshire, Durham, NH, 93 pages
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