Chemistry Commons^™

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, …

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, …

Nsf Career Award Supports Schwartz's Research On The Chemical Process For Making Rubber Component, Marcus Wolf

General University of Maine Publications

advance his ongoing dissection of the Lebedev process. The well-known, multi-step chemical reaction is used to make butadiene from biomass-derived ethanol. However, little research has been conducted on the Lebedev process at the molecular level. Understanding the intricacies of this process will help researchers create new catalysts necessary for the chemical reactions to make goods from both petroleum and biomass, that would increase butadiene yield.

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 …

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 …

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 …

Development Of Bismuth Oxyhalide Photocatalysts For Environmental And Industrial Applications, Robert Arthur

Electronic Theses and Dissertations

Heterogeneous semiconductor photocatalysis, of interest for water splitting and environmental remediation applications, uses light to drive reactions. Metal oxide and sulfide semiconductors have been previously studied but have limitations that include large band gap energies and high rates of recombination. Bismuth oxyhalides (BiOX) are an emerging class of photocatalysts with tunable band gaps and low rates of recombination due to their unique crystal structures. Studies of BiOX photocatalytic activity have largely focused on removal of azo dyes from aqueous solutions, with little attention paid to degradation byproducts. Furthermore, these catalysts have not been explored as a means to conduct organic …

Extraction And Purification Of (E)-Resveratrol From The Bark Of Maine's Native Spruces, Panduka S. Piyaratne

Electronic Theses and Dissertations

Resveratrol is a plant secondary metabolite which protects plants from pathogenic invasions and acts as a remedial agent against injury, stress, and tissue damage by UV radiation. With its characteristic stilbene structure, resveratrol adopts (E) and (Z) isomeric forms. However, the (E) isomer is the most biologically active and abundant form of resveratrol in nature.

(E)- Resveratrol confers a variety of benefits to human health and well-being. Besides its antioxidant activity, the role of (E)-resveratrol as an anti-inflammatory, anti-aging, cardioprotection, and anticancer agent has been a widely explored research interest. …

Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu

Electronic Theses and Dissertations

Chemiresistive metal oxide gas sensors based on materials such as SnO₂, ZnO, and TiO₂, have been investigated extensively by many researchers for a wide range of applications. The band bending model, based on the surface chemistry of highly reactive ionosorbed species (O₂^- or O^-) and the semiconducting material properties of SnO₂, TiO₂ and ZnO, adequately predicts the dependence of the change in sensor conductivity (Δσ) as a function of target gas pressure and temperature. However, the band bending model is not applicable to gas sensors based on reducible oxides …

Detrital Protein Contributes To Oyster Nutrition And Growth In The Damariscotta Estuary, Maine, Usa, Cheyenne M. Adams

Electronic Theses and Dissertations

Oyster aquaculture is an expanding industry that relies on identifying and utilizing natural estuarine conditions for the economically viable production of a filter-feeding crop. The eastern oyster, Crassostrea virginica, is the principal species currently cultured in Maine. In addition to preferentially consumed phytoplankton, various detrital complexes (non-algal and/or non-living organic matter) may provide some nutrition to C. virginica between times of phytoplankton abundance. Here I investigated the importance of detrital proteins in supporting the growth of oysters cultured in the upper Damariscotta Estuary. Oyster aquaculture in this area is highly successful and previous reports indicate that labile detrital protein …

Method Development For Vitamin C Quantification In Two Complex Matrices, Hannah D. Hutt

Electronic Theses and Dissertations

The following liquid chromatographic (LC) method developments and applied research studies were done using two complex food matrices, potatoes and elderberries, which are common to the state of Maine. Potatoes are Maine’s largest agricultural crop, a staple food in most U.S. households, and are, from an analytical standpoint, considered a complex matrix due to the high starch content that can be difficult to remove without degrading or removing nutrients in the process. Elderberries are an emerging crop in the U.S. because of their antioxidant and anti-viral properties and are found growing wild, throughout Maine. Elderberries are also considered a complex …

Detection Of Iron (Iii) Using Magnetic Nanoparticles, Kaiya Hansen

Electronic Theses and Dissertations

The goal of this work was to develop an iron (III) sensor which can be mounted on buoys and gliders and automatically measure iron (III) in the ocean. The method investigated in this thesis was based on anchoring the iron (III) chelator desferrioxamine B (DFB) to magnetic particles. DFB selectively binds iron (III), resulting in a complex which produces a broad absorbance band at 430 nm. This band can be measured via UV-Vis spectroscopy (UV-Vis). However, measuring oceanic iron (III) directly in solution is difficult because the concentrations can be very low, sometimes less than 1 nM. This problem could …

Room Temperature Tunable Energy Transfer Systems In Different Solvents, Zhonghua Guo

Electronic Theses and Dissertations

The focus of this thesis is on d⁸ and d¹⁰ metal-metal interactions, e.g. weak bonding in homometallic and heterometallic systems in liquid solutions, the tunability of luminescent energy due to the variation of metal-metal interaction strength in different solvents and different concentrations, as well as energy transfer from the luminescent energy tunable d⁸ and d¹⁰ metal ions clusters as donor ions to the lanthanide ions as acceptor ions at room temperature. First, energy transfer has been studied between dicyanoaurate(I) luminescent nanocluster donor ions and Eu³⁺ and Tb³⁺ acceptor ions in aqueous solutions. The emission …

Improving Performance Characteristics Of Hyphenated Preconcentrator Gc Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A "Gold Standard" For Sensor Development, Touradj Solouski

University of Maine Office of Research Administration: Grant Reports

Professor Touradj Solouki of the University of Maine at Orono is supported by the Analytical and Surface Chemistry Program to investigate cryofocusing of analytes in an Electrospray Ionization Fourier Transform Ion Cyclotron Resonance (ESI-FT-ICR) mass spectrometer. To overcome sensitivity problems of FT-ICR, Professor Solouki has added a pre-concentration (PC) gas chromatograph (GC) step to his setup. The goal of this Small Grant for Exploratory Research is to add an additional device: a cryofocuser after the GC. This is predicted to improve the detection limit by two orders of magnitude, and mass resolving power by a factor of 5-10. The PI …

Exciplex Tuning And Optical Memory Studies For Dicyanoargentate(1) And Dicyanoaurate(1) Ions Doped In Potassium Chloride Crystals Extension To Mixed Metal Gold And Silver Systems, Samanthika Ruvinie Hettiarachchi

Electronic Theses and Dissertations

Exciplex tuning and optical memory behavior of [Ag(CN)₂^-] and [Au(CN)₂^-] ions doped in KCl host crystals, pure KAg(CN)₂, and pure KAU(CN)₂ have been studied. Additionally, d¹⁰-d¹⁰ (KAu(CN)₂-KAg(CN))₂) and d¹⁰-d⁸ (KAu(CN)₂, KAg(CN)₂- K₂Pt(CN)₄) mixed metal systems have been synthesized and characterized. Several ultraviolet and visible emission bands are observed for [Ag(CN))₂^-] and [Au(CN)₂^-] ions doped in KC1 host crystals. Each emission band becomes dominant at a characteristic excitation …

Computer Simulations Of Confined Systems, Jayendran C. Rasaiah

University of Maine Office of Research Administration: Grant Reports

Jayendran Rasaiah of the University of Maine is supported by an award from the Theoretical and Computational Chemistry program with partial funding provided by the Experimental Program to Stimulate Competitive Research for the development of computational methods to simulate water and other solvents in confined systems, such as carbon nanotubes and the interior of proteins. Other systems which are being studied include capillary evaporation of water between hydrophobic plates, water near surfaces and water between charged membranes. The development of better water potentials for a variety of applications is a major goal of the research. Rasaiah is also developing efficient …