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Articles 31 - 60 of 146
Full-Text Articles in Chemistry
Electrochemical Determination Of Surface Area-To-Volume Ratio For Metal Nanoparticle Analysis., Jay Narayan Sharma
Electrochemical Determination Of Surface Area-To-Volume Ratio For Metal Nanoparticle Analysis., Jay Narayan Sharma
Electronic Theses and Dissertations
This dissertation describes an electrochemical approach for measuring the surface area-to-volume ratio (SA/V) of electrode-attached metal nanoparticles (NPs), which was used to analyze their size, aggregation state, and porosity. This dissertation further describes the effect of the metal NP electrode assembly method on the SA/V, which is related to metal NP catalytic activity and stability. Cyclic voltammetry (CV) in acid electrolyte followed by anodic stripping voltammetry (ASV) in KBr electrolyte allows the electrochemical measurement of the SA/V of electrode-attached Au nanospheres (NSs). In CV, the forward scan produces a thin surface Au2O3 layer on the Au NSs. …
Convective Instabilities Derived From Dissipation Of Chemical Energy, Reuben H. Simoyi, Matthew W. Eskew
Convective Instabilities Derived From Dissipation Of Chemical Energy, Reuben H. Simoyi, Matthew W. Eskew
Chemistry Faculty Publications and Presentations
Oxidation reactions of a series of organosulfur compounds by chlorite are excitable, autocatalytic, and exothermic and generate a lateral instability upon being triggered by the autocatalyst. This article reports on the convective instabilities derived from the reaction of chlorite and thiourea in a Hele-Shaw cell. Reagent concentrations used for the development of convective instabilities delivered a temperature jump at the wave front of 2.1 K. The reaction zone was 2 mm and due to normal cooling after the wave front, this induced a spike rather than the standard well-studied front propagation. Localized spatiotemporal patterns develop around the wave front. This …
Flavin Oxidation In Flavin-Dependent N-Monooxygenases, Reeder M. Robinson, Catherine A. Klancher, Pedro J. Rodriguez, Pablo Sobrado
Flavin Oxidation In Flavin-Dependent N-Monooxygenases, Reeder M. Robinson, Catherine A. Klancher, Pedro J. Rodriguez, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H2O2 is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD-N5 atom. In the …
Oxidative Depolymerization Of Lignin To Low Molecular Weight Aromatics, Yang Song
Oxidative Depolymerization Of Lignin To Low Molecular Weight Aromatics, Yang Song
Theses and Dissertations--Chemistry
To date, most lignocellulosic biorefinery strategies have focused on optimizing conversion of cellulose to ethanol, leaving lignin as an underutilized biomass constituent. Lignin is engineered by nature with the intent to protect plants from chemical and biological attack; this leaves lignin with high structural irregularity and recalcitrance, rendering conversion of the lignin macromolecule to valuable products particularly challenging. Nevertheless, given that the economics of cellulosic ethanol production are strongly dependent on the value that can be obtained for the lignin co-product, the successful valorization of lignin is a crucial step in the transition towards a bio-based economy.
This thesis focuses …
Atom-Specific Activation In Co Oxidation, Simon Schreck, Elias Diesen, Jerry Larue, Hirohito Ogasawara, Kess Marks, Dennis Nordlund, Matthew Weston, Martin Beye, Filippo Cavalca, Fivos Perakis, Jonas Sellberg, André Eilert, Kyung Hwan Kim, Giacomo Coslovich, Ryan Coffee, Jacek Krzywinski, Alex Reid, Stefan Moeller, Alberto Lutman, Henrik Öström, Lars G. M. Pettersson, Anders Nilsson
Atom-Specific Activation In Co Oxidation, Simon Schreck, Elias Diesen, Jerry Larue, Hirohito Ogasawara, Kess Marks, Dennis Nordlund, Matthew Weston, Martin Beye, Filippo Cavalca, Fivos Perakis, Jonas Sellberg, André Eilert, Kyung Hwan Kim, Giacomo Coslovich, Ryan Coffee, Jacek Krzywinski, Alex Reid, Stefan Moeller, Alberto Lutman, Henrik Öström, Lars G. M. Pettersson, Anders Nilsson
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We report on atom-specific activation of CO oxidation on Ru(0001) via resonant X-ray excitation. We show that resonant 1s core-level excitation of atomically adsorbed oxygen in the co-adsorbed phase of CO and oxygen directly drives CO oxidation. We separate this direct resonant channel from indirectly driven oxidation via X-ray induced substrate heating. Based on density functional theory calculations, we identify the valence-excited state created by the Auger decay as the driving electronic state for direct CO oxidation. We utilized the fresh-slice multi-pulse mode at the Linac Coherent Light Source that provided time-overlapped and 30 fs delayed pairs of soft …
The Investigation Of The Chlorine Initiated Oxidation Of 2-Phenylethanol And Stability Of Superalkali Lithium Substituted Silyls., Adam Otten
Master's Theses
This thesis investigates the combustion potential of 2-phenylethanol and the superalkali properties of small lithium substituted silicon compounds. All combustion experiments were performed at the Advanced Light Source of Lawrence Berkeley National Laboratory at the Chemical Dynamics Beamline 9.0.2. The chlorine initiated oxidation of 2PE was investigated at 298 and 550 K using a multiplex photoionization mass spectrometer, coupled with the tunable vacuum ultraviolet radiation. Reaction products were identified using kinetic time traces and photoionization spectra.
Additionally, the stability of small superalkali silicon-lithium compounds has also been investigated. All structures and energetics were calculated using the CBS-QB3 composite method.
The …
H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler
H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler
Chemistry Faculty Research
Water adsorbed at the metal-support interface (MSI) plays an important role in multiple reactions. Due to its importance in CO preferential oxidation (PrOx), we examined H2 oxidation kinetics in the presence of water over Au/TiO2 and Au/Al2O3 catalysts, reaching the following mechanistic conclusions: (i) O2 activation follows a similar mechanism to that proposed in CO oxidation catalysis; (ii) weakly adsorbed H2O is a strong reaction inhibitor; (iii) fast H2 activation occurs at the MSI, and (iv) H2 activation kinetics are inconsistent with traditional dissociative H2 chemisorption on metals. Density …
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman
Chemistry Faculty Publications
Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric transport. …
Oxidation Of Benzylic Alcohols And Lignin Model Compounds With Layered Double Hydroxide Catalysts, Justin K. Mobley, John A. Jennings, Tonya Morgan, Axel Kiefer, Mark Crocker
Oxidation Of Benzylic Alcohols And Lignin Model Compounds With Layered Double Hydroxide Catalysts, Justin K. Mobley, John A. Jennings, Tonya Morgan, Axel Kiefer, Mark Crocker
Chemistry Faculty Publications
Alcohol oxidation to carbonyl compounds is one of the most commonly used reactions in synthetic chemistry. Herein, we report the use of base metal layered double hydroxide (LDH) catalysts for the oxidation of benzylic alcohols in polar solvents. These catalysts are ideal reagents for alcohol oxidations due to their ease of synthesis, tunability, and ease of separation from the reaction medium. LDHs synthesized in this study were fully characterized by means of X-ray diffraction, NH3-temperature programmed desorption (TPD), pulsed CO2 chemisorption, N2 physisorption, electron microscopy, and elemental analysis. LDHs were found to effectively oxidize benzylic alcohols …
Photochemical Investigation Of High-Valent Metal-Oxo Intermediates Containing Corrole And Light-Harvesting Porphyrin Ligands, Jonathan Malone
Photochemical Investigation Of High-Valent Metal-Oxo Intermediates Containing Corrole And Light-Harvesting Porphyrin Ligands, Jonathan Malone
Masters Theses & Specialist Projects
In enzymatic and synthetic catalytic oxidations, high-valent iron-oxo intermediates play a vital role as the active oxidant. In this regard, many synthetic metal catalysts are designed as biomimetic models to resemble the active site of Cytochrome P450 enzymes (P450) which are the predominant oxidation catalysts in nature. Vitamin B12 cofactors, with a corrole-like structure corrin, are also utilized in some of the more difficult reactions in nature such as rearrangement and reductase reactions.
In this work, application of the promising photochemical method to corrolecontaining ligands systems showed much success in the generation of manganese(V)-oxo corrole intermediates using two electron-deficient corrole …
A Multi-Size Study Of Gold Nanoparticle Degradation And Reformation In Ceramic Glazes, Nathan Nl. Dinh, Luke T. Dipasquale, Michael C. Leopold, Ryan H. Coppage
A Multi-Size Study Of Gold Nanoparticle Degradation And Reformation In Ceramic Glazes, Nathan Nl. Dinh, Luke T. Dipasquale, Michael C. Leopold, Ryan H. Coppage
Chemistry Faculty Publications
Most traditional ceramic glazes employ high amounts of transition metal colorants that are toxic to the environment and can cause health issues in humans through surface leaching. Gold nanoparticles (Au-NPs) have been found to be environmentally friendly and non-toxic alternative metal colorant in ceramic glazes. The plasmon band observed with Au-NPs can result in vibrant solutions by manipulating NP size, shape, and concentration; however, the effects of traditional firing in both reductive and oxidative kilns on Au-NPs are poorly understood. Aside from ancient art processes whose mechanisms have not been fully explored, the use of Au-NPs as suspended ceramic glaze …
Analysis Of Oxidation Of Carbon Monoxide On Rh (110), Razan Tanbour
Analysis Of Oxidation Of Carbon Monoxide On Rh (110), Razan Tanbour
Senior Honors Theses and Projects
81% of all rhodium (Rh) is used in automobile catalytic converters. Consequently, researchers have dedicated a lot of effort into understanding the behavior of nonmetal oxides on a Rh surface. Using a computer simulation program, we have studied the absorption and oxidation of carbon monoxide (CO) on a terraced Rh surface (lattice) with a width of three and a height of 10000 using a mechanism that describes the behavior at low temperatures. Varying the reaction activation energies (rate constants), and the mobility of the CO, led to changes in the surface coverages of oxygen and CO. Specifically, increasing the activation …
Kinetics Of Silver(I)-Catalyzed Oxidation Of Allyl Alcohol By Peroxodiphosphate Inacetate Buffers, Priyamvada Sharma, Riya Sailani, Deepmala Pareek, Chandra Lata Khandelwal
Kinetics Of Silver(I)-Catalyzed Oxidation Of Allyl Alcohol By Peroxodiphosphate Inacetate Buffers, Priyamvada Sharma, Riya Sailani, Deepmala Pareek, Chandra Lata Khandelwal
Turkish Journal of Chemistry
The kinetics and mechanism of silver(I)-catalyzed oxidation of allyl alcohol with peroxodiphosphate in acetate buffers have been studied. The rate is independent of allyl alcohol concentration. The effect of other reaction parameters such as hydrogen and acetate ions has also been studied. The rate law accounting for all experimental observations corresponds to the proposed mechanism. The energy and entropy of activation have also been evaluated by employing Eyring plots.
Determination Of The Oxidative Capacity Of Soot Toward Gsh And Characterization Of Soot Physicochemical Properties, Kaylee Troth
Determination Of The Oxidative Capacity Of Soot Toward Gsh And Characterization Of Soot Physicochemical Properties, Kaylee Troth
All Master's Theses
Fine atmospheric particulate matter (PM2.5) emitted during the combustion of fossil and biomass fuels is known to adversely affect human health. While the underlying mechanisms are thought to be driven by the generation of reactive oxygen species (ROS), specific particle characteristics responsible for this detrimental effect are not well understood. In this research, the quantitative determination of the biologically relevant antioxidant, glutathione (GSH), was optimized for use as an indicator of oxidative stress to shed light on relevant particle characteristics. This was accomplished via fluorescent spectroscopy for GSH determination by way of reaction with o-phthalaldehyde (OPA), a …
Oxidation Of Dibenzothiophene To Dibenzothiophene-Sufone Using A Molybdenum (Vi) Oxide Catalyst: A Kinetic Study Testing Solvent Dependency And Mole Ratio Efficiency, Tomas Trevino Jr.
Oxidation Of Dibenzothiophene To Dibenzothiophene-Sufone Using A Molybdenum (Vi) Oxide Catalyst: A Kinetic Study Testing Solvent Dependency And Mole Ratio Efficiency, Tomas Trevino Jr.
Theses and Dissertations
Oxidative desulfurization (ODS) is currently a solution to hydrodesulphurization. Currently, industrial usage of hydrodesulphurization (HDS) is the common source for petroleum purification. Unfortunately, HDS comes with environmental and economical ramifications. Due to the problems and potential hazards being presented with HDS, ODS has become a topic of interest in research development. A kinetic study using molybdenum (VI) oxide as a catalyst was used in oxidative desulfurization. Factors such as mole ratio and solvent dependency were tested for efficiency. As activation energy was calculated to show maximum efficiency with respect to temperature and concentration. Gas Chromatography, FT-IR, and Mass Spectroscopy were …
Air-Oxidation Of Phenolic Resin Aerogels: Backbone Reorganization, Formation Of Ring-Fused Pyrylium Cations, And The Effect On Microporous Carbons With Enhanced Surface Areas, Hojat Majedi Far, Suraj Donthula, Tahereh Taghvaee, Adnan Malik Saeed, Zachary Garr, Chariklia Sotiriou-Leventis, Nicholas Leventis
Air-Oxidation Of Phenolic Resin Aerogels: Backbone Reorganization, Formation Of Ring-Fused Pyrylium Cations, And The Effect On Microporous Carbons With Enhanced Surface Areas, Hojat Majedi Far, Suraj Donthula, Tahereh Taghvaee, Adnan Malik Saeed, Zachary Garr, Chariklia Sotiriou-Leventis, Nicholas Leventis
Chemistry Faculty Research & Creative Works
This paper is a thorough investigation of the chemical transformations during pyrolytic conversion of phenolic resins to carbons, and reports that all carbons obtained from main-stream phenolic resins including phloroglucinol-formaldehyde (FPOL), phloroglucinol-terephthalaldehyde (TPOL), resorcinol-formaldehyde (RF), and phenol-formaldehyde (PF) contain fused pyrylium rings and charge-compensating phenoxides. Those four phenolic resins were prepared via a fast HCl-catalyzed process as low-density nanostructured solids classified as aerogels, which, owing to their open porosity, allowed air circulation through their bulk. In that regard, the first step of this study was the air-oxidation of those phenolic resin aerogels at 240 °C. In FPOL and TPOL aerogels, …
The Investigation And Characterization Of The Reaction Of 2-Methylfuran And 2-Methyl-3-Buten-2-Ol With O(3p) And The Photodissociation Of Xylyl Bromide Isomers, Yasmin Fathi
Master's Theses
This thesis has studied the oxidation behavior of different biofuels or additives, 2-methyl-3-buten-2-ol and 2-methylfuran, in combustion experiments at the Chemical Dynamics Beamline held at the Advanced Light Source of the Lawrence Berkley National Laboratory. The oxidation of these fuels were initiated through O(3P) and the combustion experiments were analyzed using a multiplexed chemical kinetics photoionization mass spectrometer with tunable synchrotron radiation. Products of the different reactions were identified using kinetic profiles and further characterized using the photoionization spectra. The amount of each species was calculated using branching fractions.
Additionally, the unimolecular dissociation of the xylyl bromide isomers …
Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad
Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad
Electronic Theses and Dissertations
Hydrogen is a promising carbon-free fuel / energy carrier and is an essential building block for many industrial and agricultural processes. Rising energy demands have ignited interest in the development of carbon-free and carbon neutral energy sources. In this context, hydrogen is an attractive candidate—being energy-dense, carbon-free—and easily accessible through a two-electron reduction of water. Accordingly, many electrochemical homogeneous catalyst systems have been studied, with a focus on understanding the mechanism of hydrogen evolution proceeding through metal-hydride intermediates. However, there has been a renaissance in hydrogen evolution reaction (HER) catalyst design, with many groups implicating ligand redox non-innocence as a …
Nitrate Radicals And Biogenic Volatile Organic Compounds: Oxidation, Mechanisms And Organic Aerosol, Nga Lee Ng, Steven S. Brown, Alexander T. Archibald, Elliot Atlas, Ronald C. Cohen, John N. Crowley, Douglas A. Day, Neil M. Donahue, Juliane L. Fry, Hendrik Fuchs, Robert J. Griffin, Marcelo I. Guzman, Hartmut Hermann, Alma Hodzic, Yoshiteru Iinuma, José L. Jimenez, Astrid Kiendler-Scharr, Ben H. Lee, Deborah J. Luecken, Jingqiu Mao, Robert Mclaren, Anke Mutzel, Hans D. Osthoff, Bin Ouyang, Benedicte Picquet-Varrault, Ulrich Platt, Havala O. T. Pye, Yinon Rudich, Rebecca H. Schwantes, Manabu Shiraiwa, Jochen Stutz, Joel A. Thornton, Andreas Tilgner, Brent J. Williams, Rahul A. Zaveri
Nitrate Radicals And Biogenic Volatile Organic Compounds: Oxidation, Mechanisms And Organic Aerosol, Nga Lee Ng, Steven S. Brown, Alexander T. Archibald, Elliot Atlas, Ronald C. Cohen, John N. Crowley, Douglas A. Day, Neil M. Donahue, Juliane L. Fry, Hendrik Fuchs, Robert J. Griffin, Marcelo I. Guzman, Hartmut Hermann, Alma Hodzic, Yoshiteru Iinuma, José L. Jimenez, Astrid Kiendler-Scharr, Ben H. Lee, Deborah J. Luecken, Jingqiu Mao, Robert Mclaren, Anke Mutzel, Hans D. Osthoff, Bin Ouyang, Benedicte Picquet-Varrault, Ulrich Platt, Havala O. T. Pye, Yinon Rudich, Rebecca H. Schwantes, Manabu Shiraiwa, Jochen Stutz, Joel A. Thornton, Andreas Tilgner, Brent J. Williams, Rahul A. Zaveri
Chemistry Faculty Publications
Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO3-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number …
Singlet Oxygen Generation From Poly[4-Diacetoxyiodo]Styrene And Hydrogen Peroxide, Mustafa Çatir
Singlet Oxygen Generation From Poly[4-Diacetoxyiodo]Styrene And Hydrogen Peroxide, Mustafa Çatir
Turkish Journal of Chemistry
Treatment of hydrogen peroxide with a polymer-supported hypervalent iodine compound, poly[4-diacetoxyiodo] styrene (PDAIS), generates singlet molecular oxygen ($^{1}$O$_{2})$. Singlet oxygen generation was proved by trapping with typical organic compounds such as conjugated dienes, aromatic dienes, and electron-rich alkene. When compared to monomer analogue, the use of PDAIS in peroxidation of substrates gave slightly better yields (45%-96%). Regeneration and reuse of PDAIS showed similar activity. The mechanism underlying generation of singlet oxygen and reaction scope was examined.
The Decline And Recovery Of Thermal Oxidative Stability Of Ultra-Low Sulfur Diesel Blends, Abigail Schoor Cohen
The Decline And Recovery Of Thermal Oxidative Stability Of Ultra-Low Sulfur Diesel Blends, Abigail Schoor Cohen
Electronic Theses and Dissertations
Dissertation supervised by Professor Bruce D. Beaver
The oxidative stability of ultra-low sulfur diesel (ULSD) has generally been expected to continuously decline over time. However, recent studies have suggested that it may fluctuate.1-2 In this study, the oxidative stability of stored commercially purchased ULSD was monitored with a methanol extraction method.3 In this methodology, proposed by Hardy and Wechter, fuel blends are extracted with methanol before and after thermal stressing.4 The methanol-soluble layer contains the oxygenated and oxidizable components of the fuel (SMORS) and the change in this mass upon stressing thus represents the oxidative stability of …
Biomimetic Tools In Oxidative Metabolism: Characterization Of Reactive Metabolites From Antithyroid Drugs, Kudzanai Chipiso
Biomimetic Tools In Oxidative Metabolism: Characterization Of Reactive Metabolites From Antithyroid Drugs, Kudzanai Chipiso
Dissertations and Theses
Toxicities of sulfur-based drugs have been attributed to formation of highly reactive sulfur oxo-acids and depletion of glutathione by the formation of reactive metabolites. Metabolic activation of these sulfur centers to conceivably toxic reactive metabolites (RMs) that can covalently modify proteins is considered the initial step in drug-induced toxicity. Despite considerable effort and research, detection and characterization of these RMs during drug development and therapy remains a challenge. Methimazole (MMI) and 6-propyl-2-thiouracil (PTU) are two commonly used antithyroid, sulfur-based drugs. Though effective, these drugs are associated with idiosyncratic toxicity. PTU has acquired a black box warning and physicians are calling …
Development Of Palladium Catalyzed Alkene Difunctionalization On Vinyl-Quinoline Type Substrate And Isolation Of Pd-Alkyl Intermediate, Lusha Xu
Electronic Theses and Dissertations
The synthesis of quinoline derivatives is a continuing issue facing organic chemists in both academia and industry. To address this problem, palladium-catalyzed alkene difunctionalization was developed to be a powerful and straightforward strategy of synthetic transformations for adding diversity to organic molecules. In this thesis, Pd-catalyzed olefin difunctionalization reactions of vinyl-quinoline type substrate via generating Pd-alkyl intermediates were mainly described. The reactions described herein are pursuing three significant goals: 1) to isolate and recrystallize Pd-alkyl complexes; 2) to achieve oxidation reactions on Pd-alkyl intermediate; and 3) to investigate stereochemistry of nucleopalladation step on vinyl-quinoline starting materials.
Studies On Hydroxyl Radical Formation And Correlated Photoflocculation Process Using Degraded Wood Leachate As A Cdom Source, Luni Sun, Kenneth Mopper
Studies On Hydroxyl Radical Formation And Correlated Photoflocculation Process Using Degraded Wood Leachate As A Cdom Source, Luni Sun, Kenneth Mopper
Chemistry & Biochemistry Faculty Publications
In this study, we examined hydroxyl radical (•OH) formation with respect to photoreactivity of colored dissolved organic matter (CDOM), the Fenton reaction, and photoflocculation using leachate from decaying wood. The relationship between •OH photoproduction rate and leachate optical properties (UV-visible absorption and fluorescence excitation-emission matrices (EEMS)) was studied during irradiation using a UV solar simulator. The results showed that the •OH photochemical formation rate is strongly related to humic-like fluorescence as characterized by parallel factor analysis (PARAFAC), and that these fluorescence components are more photolabile than most of the other CDOM components. Fourier transform infrared spectroscopy (FT-IR) indicated the photodegradation …
Measurement Of Antioxidant Activity Toward Superoxide In Natural Waters, D. Whitney King, Emma Berger, Zachary Helm, Eleanor Irish, Kenneth Mopper
Measurement Of Antioxidant Activity Toward Superoxide In Natural Waters, D. Whitney King, Emma Berger, Zachary Helm, Eleanor Irish, Kenneth Mopper
Chemistry & Biochemistry Faculty Publications
Antioxidants are a class of molecules that provide a protective function against reactive oxygen species (ROS) in biological systems by out competing physiologically important molecules for ROS oxidation. In natural waters, the reactivity of antioxidants gives an estimate of oxidative stress, and may determine the reactivity and distribution of reactive oxidants. We present an analytical method to measure antioxidant activity in natural waters through the competition between ascorbic acid, an antioxidant, and MCLA, a chemiluminescent probe for superoxide. A numerical kinetic model of the analytical method has been developed to optimize analytical performance. Measurements of antioxidant concentrations in pure and …
Towards Catalytic Oxidative Depolymerization Of Lignin, Justin K. Mobley
Towards Catalytic Oxidative Depolymerization Of Lignin, Justin K. Mobley
Theses and Dissertations--Chemistry
Lignin is one of the most abundant and underutilized biopolymers on earth. Primarily composed on three monolignol units (sinapyl, coniferyl, and p-coumaryl alcohol), lignin is formed through a radical pathway resulting in an assortment of linkages, of which the β-O-4 linkage is the most prevalent (up to 60% in some hardwood species). In planta, lignin plays an important role in water transport and in protecting plants from chemical and biological attack. Traditional attempts to depolymerize lignin have focused on the cleavage of β-O-4 linkages via thermal or reductive routes. However these pathways lead to low-value, unstable product mixtures. Moreover, …
The Investigation Of The Low Temperature Combustion Of Mesitylene And Tert-Amyl Methyl Ether By Synchrotron Photoionization Mass Spectrometry, Martin Yu-Hin Ng
The Investigation Of The Low Temperature Combustion Of Mesitylene And Tert-Amyl Methyl Ether By Synchrotron Photoionization Mass Spectrometry, Martin Yu-Hin Ng
Master's Theses
This thesis describes the combustion experiments performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) located at the Lawrence Berkeley National Laboratories (LBNL). The need for renewable fuel sources, the need for the study of their combustion in the contexts of homogenous charge combustion ignition (HCCI) engines can be found in Chapter 1. The components of the experimental set-up used throughout this thesis—time-of-flight mass spectrometer, Excimer laser, vacuum pumps and other components—and the components of ALS responsible in synchrotron radiation generation and processing—the linear accelerator, the booster ring, insertion devices, gas filters and monochromator are explained in …
Methodology Development In Green Chemistry: Oxoammonium Salt Oxidations And Fluoroform Incorporation, Rebecca J. Wiles
Methodology Development In Green Chemistry: Oxoammonium Salt Oxidations And Fluoroform Incorporation, Rebecca J. Wiles
University Scholar Projects
Central to the advancement of small molecule synthesis is the ability to develop methodologies that reimagine well known chemistry in a new, environmentally friendly manner. In this thesis two central themes emerge: oxoammonium salt oxidations and trifluoromethyl incorporation using fluoroform gas. Several projects have been developed surrounding oxoammonium salt chemistry, which are featured by their mild conditions, ease of use, and the metal-free, recyclable nature of the oxidant. Trifluoromethylation using fluoroform gas finds its utility in the use of a potent greenhouse gas waste product as a benchtop reagent.
Oxidation Of Dibenzothiophene To Dibenzothiophene-Sulfone Using Molybdenum (Vi) Oxide, Tungsten (Vi) Oxide, And Ratios Of Molybdenum (Vi) Oxide And Tungsten (Vi) Oxide At Atomspheric Pressure, Sean M. Pelfrey
Theses and Dissertations - UTB/UTPA
This is a study of the catalytic oxidation of dibenzothiophene to dibenzothiophene sulfone using molybdenum (VI) oxide, tungsten (VI) oxide, and mixtures of molybdenum (VI) oxide and tungsten (VI) oxide at atmospheric pressure. The oxidative desulfurization reaction is studied with respect to the kinetics and thermodynamics of the process. Five catalysts were synthesized using a precipitation reaction. The five catalysts were 100% MoO3, 75/25% MoO3/WO3, 50/50% MoO3/WO3, 25/75% MoO3/WO3, and 100% WO3. Each catalyst was calcinated at three different temperatures 250oC, 500oC, 750oC and characterized using X-Ray Diffraction. Reactions of DBT-catalyst were held, under reflux, at temperatures from 140 oC …
Methodology Development In Green Chemistry: Oxoammonium Salt Oxidations And Fluoroform Incorporation, Rebecca J. Wiles
Methodology Development In Green Chemistry: Oxoammonium Salt Oxidations And Fluoroform Incorporation, Rebecca J. Wiles
Honors Scholar Theses
Central to the advancement of small molecule synthesis is the ability to develop methodologies that reimagine well known chemistry in a new, environmentally friendly manner. In this thesis two central themes emerge: oxoammonium salt oxidations and trifluoromethyl incorporation using fluoroform gas. Several projects have been developed surrounding oxoammonium salt chemistry, which are featured by their mild conditions, ease of use, and the metal-free, recyclable nature of the oxidant. Trifluoromethylation using fluoroform gas finds its utility in the use of a potent greenhouse gas waste product as a benchtop reagent.