Physical Sciences and Mathematics Commons^™

Synthesis Of Poly(Styrene-Co-Butyl Acrylate) Pickering Emulsion With Montmorillonite Nanoparticles And Its Comparison With Sodium Dodecyl Sulfate Surfactant On Affecting The Water Barrier Properties Of Coated Paper, Chidubem H. Uchefuna

Electronic Theses and Dissertations

Water-borne barrier dispersion coatings on paper have emerged as an alternative to extrusion coatings on paper due to improved recycling, high application speed, and other end of life attributes. Pigments are often added to improve the performance of dispersion coatings. The use of pigments to form a Pickering emulsion during the polymerization step for the production of a barrier coating on paper has not been discussed in the literature.

In this study, montmorillonite (MMT) pigment varied from 0-6 % pigment volume concentration (PVC) was used to synthesize dispersion coatings consisting of poly(styrene-co-butylacrylate) latex and compared with sodium dodecyl …

Elucidating The Pd Active Sites Of Bimetallic Gold-Palladium Catalysts Using Chemisorption And Titration Techniques, Andrew T. Boucher

Electronic Theses and Dissertations

A bimetallic nanoparticle catalyst combines two different metals on an oxide support, which can increase the selectivity towards useful products that may be too tightly bound to a monometallic catalyst. To explore the surface properties of such a system, we made a group of four PdAu bimetallic catalysts with varying gold mass loadings to compare with a parent Pd catalyst. The parent catalyst was synthesized using ion exchange, and gold was added to this parent Pd catalyst using incipient wetness impregnation (IWI) to create four bimetallic catalysts. All catalysts were characterized using H₂ and CO chemisorption in tandem with …

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

Electronic Theses and Dissertations

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

Expanding Glycomic Investigations Through Thiol-Derivatized Glycans, Robert Hurst

Electronic Theses and Dissertations

N-(2-thioethyl)-2-aminobenzamide (TEAB), a novel glycan auxiliary, was synthesized and its utility was evaluated. The auxiliary was conjugated to glycans by reductive amination with the water-stable reagent 2-picoline borane complex. Glycan products, which ranged from 1 to 7 linked hexoses, were all isolated in yields ranging from 60% to 90% after purification by reverse-phase chromatography. The novel conjugate introduces a convenient, shelf-stable thiol directly onto the desired free glycans with purification advantages and direct modification with efficient reactions through alkenes, halides, epoxides, disulfides, and carboxylates in yields of 49% to 93%. Subsequently, a thiol-selective modification of the BSA protein was used …

Quantum Mechanical Studies Of Water Splitting Reaction With (Zno)3 Nanoclusters As Catalysts, Duwage C. Perera

Electronic Theses and Dissertations

With the current energy crisis, H₂ production through the water-splitting reaction has drawn attention recently. In this thesis, I studied the structural (geometry) and electronic properties (vertical detachment energy and electron affinity) of ZnO monomers and dimers using density functional theory. ZnO is a metal oxide with a 3.37 eV band gap and can be a commercially cheaper photocatalyst in hydrogen (H₂) production. The B3LYP/DGDZVP2 pair was selected after investigating different pairs of exchange functionals and basis sets to study the hydration, hydrolysis, and water-splitting reaction. The singlet-triplet energy gaps of small (ZnO)_n clusters (n=1-6) of …

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

Electronic Theses and Dissertations

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

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

Gold (I) Tetrathiomolybdate Clusters: Synthesis, Characterization, Computational Studies, And Reactivity With Thiophenol And Selenophenol, Dhirgam Humaidy

Electronic Theses and Dissertations

This thesis describes the synthesis and reactivity of heterometallic complexes containing medicinally active Au(I) and tetrathiomolybdate, [MoS₄]^2-. The research is motivated by the idea of multifunctional drugs, which are designed to treat diseases through two or more mechanisms of action. Five clusters of the general form, [MoS₄(AuL)₂] were prepared: C-1 (L=IPr), C-2 (L=IBzMe), C-3 (L=IMes), C-4 (L=PPh₃), and C-5 (L=PEt₃). The clusters with NHC ligands, C-1, C-2, and C-3 were prepared for the first time and thoroughly characterized by ¹H NMR,¹³C{¹H} …

Stereoselective Synthesis Of Pseudosaccharide Derivative And Bisphosphoramidate Core Of Em2487, Saad Z. Mohammed Ali

Electronic Theses and Dissertations

HIV is among the leading causes of death worldwide resulting in over 1 million deaths annually according to the World Health Organization. Despite advances in the treatment of HIV, eradicating this pathogen remains a top priority in the medical and scientific communities. EM2487 is a natural product produced by Streptomyces sp. Mer-2487 that possesses promising activity against HIV. Specifically, EM2487 is a potent and selective inhibitor of HIV replication in both acutely and chronically infected cells. The observed HIV activity is hypothesized to be the result of targeting the Tat-TAR (trans-activation response) element which activates RNA polymerase II at the …

Intersections Of Environmentalism, Chemistry, And Racism: An Experimental Study Of Halobenzene Hydrogenolysis And Critical Communication Studies Of Equitable Learning Practices Rooted In Black Feminism, Lauren O. Babb

Electronic Theses and Dissertations

Increasing concentrations of fluorinated aromatic compounds in surface water, groundwater, and soil pose threats to the environment. Fundamental studies that elucidate mechanisms of dehalogenation for C-X compounds (where X represents a halide) are required to develop effective remediation strategies. For halogenated benzenes, previously published research has suggested that the strength of the C-X bond is not rate-determining in the overall rate of dehalogenation. Instead, the rate-determining step has been hypothesized to be adsorption of the C-X compound onto the surface of a catalyst. Building on this hypothesis, in this work, we examine the reaction kinetics of fluorobenzene conversion to benzene, …

Synthesis And Evaluation Of Water-Dispersed Aryl-Gold Nanoparticles And Applications In Catalysis, Ahmad Al Ahmad

Electronic Theses and Dissertations

Gold nanoparticles have been used in environmental remediation as catalysts through biological and chemical redox reactions of many types of industrial waste including nitroarenes, organic dyes, carbon monoxide, and others. These reactions occur in harsh environmental conditions (e.g. changing temperature, presence of salts, extreme pH solutions) which require robust nanoparticles that can keep their activity and resist aggregation. This thesis describes the synthesis, characterization, and investigation of the catalytic activity of gold-aryl nanoparticles. Gold–aryl nanoparticles (AuNPs-COOH) fabricated using a mild reduction process of a molecular aryldiazonium gold(III) salt [HOOC-4-C6H4N≡N]AuCl4 showed high stability in the presence of high ionic strength salt, …

Age, Growth, Foraging, And Trophic Ecology Of Bigeye (Thunnus Obesus) And Yellowfin (Thunnus Albacares) Tuna In Continental Shelf And Slope Regions Of The Northeast U.S., Riley S. Austin

Electronic Theses and Dissertations

Traditional stock assessments require, in part, accurate knowledge of growth relationships to estimate a variety of aspects involved in population conservation management of exploited species. In addition, the local distribution and condition of top pelagic predators is driven by detection of abundant forage aggregations and along with traditional stock assessments, should be considered for effective management of marine populations. Empirical analyses of these data are severely lacking for bigeye (Thunnus obesus) and yellowfin (Thunnus albacares) tuna in the Atlantic Ocean, especially for the former. Given historical studies’ observations of these two top predators use as biological samplers due to their …

Fabrication Of Particulates For Detecting Trace Level Analytes In Water Using Optical Spectroscopy And For Developing Thermoelectric Materials, Mohammed Nayeem Ibnul

Electronic Theses and Dissertations

The underlying concepts developed in this thesis involve particulate fabrication of known size using a bottom-up synthesis or a top-down milling process. This bottom-up approach was used for detection of analytes in water. Conventional UV-Vis spectroscopic based detection methods require target analytes to be soluble or have enough vapor pressure for analysis in the gas phase. We achieved an order in magnitude improvement in the detection limit over the standard molybdenum blue method for phosphate and arsenate by conversion of target analytes present in solution to a solid for quantification by UV-Vis and IR spectroscopy. Furthermore, by recording a visible …

Development Of Methods For Surface Modification Of Semiconductor Photocatalysts And Biopolymers For Applications In Water Treatment And 3d Printing, Sabrina Sultana

Electronic Theses and Dissertations

Surface modifications of metal oxides and polymer substrates are widely adopted approaches to alter the properties of these materials for use with specific applications. In the first part of my thesis, I describe how we have modified the surface of magnetic particles (Fe3O4) with layers of SiO2 and TiO2 to generate photocatalysts that remove toxic chemicals from drinking water. Semiconductor photocatalysts, such as TiO2 have gained much interest over the last 20 years as promising materials for water treatment. However, a main drawback centers on the difficulty to remove the catalyst from the water which has made it very difficult …

Nanomaterials For Sustainability: Using Spectroscopy And Quantum Chemistry For Microkinetic Modeling Of Thermo- And Photo- Catalysts, Amir Rahmani Chokanlu

Electronic Theses and Dissertations

Heterogeneous catalysis, including thermal- and photocatalysis, is a key technology toward developing industrial processes for a sustainable future. Therefore, the study of surface reactions and catalyst properties includes most studies in this area. There has been extensive work put into developing experimental and computational tools to understand surface and interface phenomena, describe mechanistic chemical transformations, and simulate the behavior of surface reactions to develop better catalysts and more efficient processes.

This thesis describes experimental and theoretical investigations to explain the reaction mechanism of ethanol conversion to value-added products over an MgO/SiO2 catalyst, a kinetic model describing the surface changes during …

Functionalized 𝜹-Hexalactones (Fdhls): Bio-Derivable Monomers To Synthesize Renewable Polyester Thermoplastics, Atik Faysal

Electronic Theses and Dissertations

Most thermoplastics are made from limited fossil-fuel sources and these plastics have very deleterious impacts on the environment. Finding a renewable source to synthesize new thermoplastic polymers with tunable properties like biodegradability, heat resistance, and moisture resistance are ongoing research interests. Lignocellulosic biomass is a promising renewable feedstock for biobased monomers and polymers production. In this work, functionalized 𝛿-hexalactone (FDHL) monomers are hypothesized to be synthesizable from lignocellulosic sourced hydroxymethyl furfural (HMF) and lignin-derived pendant groups, generating a variety of aliphatic polyesters and potentially overcome current polymer challenges. Achieving a higher glass transition temperature (T_g) is one of …

Charged-Particle Interactions To Generate Novel Coatings And Materials, Pradnya D. Rao

Electronic Theses and Dissertations

A typical paper coating formulation contains anionically charged pigments and latex to provide a high-quality surface for printing. However, during application and drying, the latex can migrate to the surface or deep into the paper, resulting in weak coating layers or the need to use a high latex content to obtain the same strength properties. In this thesis, we have explored the introduction of cationically charged particles into the suspension as a way to reduce the amount of binder in the coatings, improve coating strength and reduce binder migration. With these aims in mind, we have generated cationic precipitated calcium …

The Impact Of Project-Based Learning On Students In High School Chemistry In Rural Maine, Brianna Degone

Electronic Theses and Dissertations

Project-based learning (PBL) is an instructional strategy that is promoted throughout education for its use of active learning and ability to connect to real-world applications. Studies have been conducted on PBL ranging from early elementary grades through graduate courses, however little research considers the effectiveness of PBL at the secondary science level. This thesis considers the use of PBL and describes the implementation of a PBL unit in a rural Maine 11th grade chemistry classroom. The thesis aims to better understand the impact PBL has on students’ content learning and additional skills acquired through the PBL learning process. Along with …

Gradient Generating Microfluidic Coculture System For Disease Modeling And Neural Development, Phaneendra Chennampally

Electronic Theses and Dissertations

Cellular microenvironment or cell niche plays an important role in developmental biology and disease pathophysiology. Physical or chemical signals in microenvironment drive the cellular activity. These signaling molecules are generated from the surrounding cells/tissues as part of intercellular communication; a fundamental property of a cell. Dynamic profile of these signaling molecules in the microenvironment plays a pivotal role in transfer of molecular information from cell to cell in disease proliferation or fate determination. Recapitulating these signaling cues in an in vitro study is difficult to achieve using standard cell culture techniques. However microfluidic systems are capable of addressing these issues, …

Asymmetric Synthesis Of Phosphate Mimics: From Chemistry To Biotechnology, Ahmed Numan

Electronic Theses and Dissertations

Oligonucleotide based therapeutics have been pursued in the clinic for the treatment of many disease indications. However, unmodified oligonucleotides are polyanionic macromolecules with poor drug-like properties. Modifications of the phosphodiester backbone provide resistance to nucleases in vivo, making them more efficacious than unmodified nucleotides. However, these backbone modifications have added the structural complexity of a stereogenic phosphorus center. Stereochemically pure isomers exhibit differential efficiency dependent on its enantiopurity. The catalytic, stereocontrolled synthesis of a phosphorus-stereogenic center is challenging, and traditionally, depends on a resolution or use of stochiometric auxiliaries. Herein, asymmetric nucleophilic catalysis has been investigated to provide enantio-enriched phosphonates …

To Know The Land With Hands And Minds: Negotiating Agricultural Knowledge In Late-Nineteenth-Century New England And Westphalia, Justus Hillebrand

Electronic Theses and Dissertations

Ever since the eighteenth century, experts have tried to tell farmers how to farm. The agricultural enlightenment in Europe marked the beginning of a long arc of new experts aiming to change agricultural knowledge and practice. This dissertation analyzes the pivotal period in the late nineteenth and early twentieth century in Germany and the United States when scientists, improvers, and market agents began to develop comprehensive ways to communicate agricultural innovation to farmers. In a functional approach to analyzing the negotiation of agricultural knowledge through its communication in things, words, and practices, this dissertation argues that the process of change …

Development Of Nanostructured Titania-Incorporated Photocatalysts For Environmental Applications, Sudheera B. Yaparatne

Electronic Theses and Dissertations

Ultraviolet (UV) radiation application in water and wastewater treatment has become a common approach for inactivation of protozoa and other pathogenic microorganisms. However, degradation of most organic compounds, such as taste and odor products prevalent in surface waters, has not been proven effective with direct UV photolysis. Advanced oxidation processes (AOPs) that involve efficient photocatalysts like TiO₂ show an advantage over direct UV photolysis providing fast reaction rates and non-selective oxidation of contaminants. However, the real-world application of TiO₂ in water and wastewater treatment is limited due to difficulties in separating the suspended nanosized particles following treatment, the …

Development Of Methods For Determining Water Content In Oil Using Infrared Spectroscopy, Sfoog Hamad Saleh

Electronic Theses and Dissertations

Karl Fischer Titration (KFT) is the “gold standard” method for measuring the amount of water in oils. KFT is a laborious and time-consuming method that requires expensive and hazardous chemicals which has provided the impetus to develop alternative methods. In this thesis, we investigated three approaches for determining water content in oils that are based on the use of infrared spectroscopy. In the first approach, we developed a simple method for measuring water concentrations from 1 to 5000 ppm in various types of oil that uses no hazardous, and expensive, chemical reagents or matrix specific calibrations. This approach involves capturing …

Synthesis And Photophysical Studies Of Nitrogen Heterocycles Containing Benzothiazines, Benzothiazoles, Indoles And Quinolines, Ealin N. Patel

Electronic Theses and Dissertations

Nitrogen heterocycles such as quinolines, benzothiazines, benzothiazoles, and indoles are widely found in nature and these compounds have significance in organic and medicinal chemistry, biochemistry as well as materials science. Monomeric units of eumelanin (brominated 5,6- dimethoxyindolecarboxylate derivatives) were synthesized and regioselectively functionalized to form three monobrominated, three dibrominated, and a tribrominated variant using thermally induced nitrene insertions. After deprotection, three monobrominated 5,6-dihydroxyindole carboxylate (DHICA) derivatives were synthesized, and their UV-Vis absorbance was compared to DHICA. Bominated DHICA derivatives showed similar λmax as DHICA (~330 nm) but did not show aerial oxidation as evident by absence of chromophore absorbance at …

Understanding Biomass Upgrading Through Hydrogenolysis Reactions: Kinetics And Mechanism, Jalal Tavana

Electronic Theses and Dissertations

This dissertation involves several hydrogenolysis reactions but is mainly focused on hydrodechlorination (HDC) of chlorobenzene (PhCl) and hydrodeoxygenation (HDO) of 2-furancarboxylic acid (FCA). Hydrodechlorination of PhCl has been the subject of research for some time. Here, we used a Pd/C catalyst to study this reaction though rigorous kinetics and mechanistic analyses in a CSTR reactor. The H₂/D₂ kinetic isotope effect (KIE) experiment revealed that H₂ is not involved in a rate controlling step. The kinetics data are in agreement with similar systems reported before and follow a first-order dependence on chlorobenzene, half order for hydrogen and …

An Intramolecular Method For The Formation Of Glycosidic Bonds, Sudeera Nadeeshani Kamburugamuwa Kamburugamuwe Loku Acharige

Electronic Theses and Dissertations

The improved understanding of carbohydrate functions in biological systems has increased the demand for well-characterized and pure carbohydrates in biomedical research. Chemical synthesis is the most feasible method to satisfy the scientific demand despite the inherent challenges of the glycosylation reaction. Therefore, it is essential to investigate novel methods for the formation of glycosidic bonds. In this work, an intramolecular method was developed using a thio-methylene-silyl linker to tether a glycosyl donor and acceptor. The glycosylation conditions resulted in the formation of both anomeric isomers with a preference for the inversion pathway, which is inconsistent with an entirely intermolecular glycosylation …

Investigations On The Helix-Coil Transition Inside Nanotubes, Dylan Suvlu

Electronic Theses and Dissertations

Proteins are the workhorses of biology and are essential to life as we know it. A protein’s function in the cell is intimately related to its three-dimensional structure. Thus, understanding structure formation in proteins has been an essential goal in molecular biology. Experiments indicate proteins start acquiring structure inside the ribosome—the cellular manufacturing plant of proteins—and the process is particularly important for membrane proteins. Therefore, the ribosome appears to play an active role in facilitating protein structure acquisition. However, how and when the ribosome accomplishes this task remains poorly understood. To better understand this process, we conducted molecular dynamics computer …

Phenolic Phytochemicals And Their Antioxidant Activities In Maine-Grown Asian, American-Hybrid, And European Plums, Hye Weon Hwang

Electronic Theses and Dissertations

Plum fruits of 16 plum cultivars derived from three species, Asian, American-hybrid, and European plums, and one cultivar of an interspecific hybrid between Asian plum and apricot were investigated to identify and quantify two major groups of phenolic phytochemicals, anthocyanins and hydroxycinnamic acids (HCAs) by HPLC–DAD/MS. The plums were harvested from 2014 to 2017. Some cultivars were analyzed through consecutive years to determine year-to-year differences and to evaluate the maturity impacts on the concentration of anthocyanins and HCAs from the partial-ripe stage and tree-ripe stage. Anthocyanins were present in red−purple colored plums, but their profiles varied among cultivars and species. …

Polysaccharide And Silver Nanoparticles Based Hydrogels, Porous Materials, And Sensors, Muhammad R. Hossen

Electronic Theses and Dissertations

Cellulose based hydrogels and porous materials are gaining significant attention across a wide range of applications due to the natural abundance, biodegradability and physicochemical tunability of this polysaccharide. Cellulose nanofibrils (CNF) outperform cellulose fibers in terms of physicochemical tunability since CNF possess relatively high surface area. However, superior dispersibility of CNF in aqueous phase makes it challenging for traditional methods to dewater CNF suspensions to fabricate robust hydrogels and porous materials. In this dissertation, a novel scalable capillary based method to dewater CNF suspensions is invented as well as CNF hydrogels and porous materials with a broad range of porosity …

Microbial Diversity Of The Symbiotic Colony Of Bacteria And Yeast (Scoby) And Its Impact On The Organoleptic Properties Of Kombucha, Danielle L. St-Pierre

Electronic Theses and Dissertations

Kombucha is an effervescent fermented tea beverage that is gaining popularity for its probiotic nature and purported health benefits. The market for kombucha is expected to reach $1.8 billion by the year 2020. The composition of microbes that compose the symbiotic colony of bacteria and yeast (SCOBY) is highly variable with some species commonly found from the Gluconobacter, Acetobacter, Zygosaccharomyces, Saccharomyces, and Schizosaccharomyces genera.

It was hypothesized that different SCOBYs, obtained from different sources would vary in microbial diversity and produce different biochemical and flavor profiles in the resulting beverage over several generations. Kombucha is a fermented …

Synthesis And Characterization Of Heteronuclear Inorganic Complexes For The Photodegradation Of Persistant Organic Pollutants, Matthew A. Moyet

Electronic Theses and Dissertations

The focus of this thesis is to investigate the structural modification and characterization potential of common photocatalysts that have various uses for environmental remediation purposes. Pollution involving organic chemicals is one of the most common scenarios found in communities throughout the country. Efforts to rid contaminated drinking water supplies of these chemicals include physical and chemical filters, which have limited ability and efficacy. This lack of efficient filtration services has led to an increased demand for more effective treatment methods. Chemical species that react in the presence of light are known as photocatalysts and have been used in previous studies …