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2019

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Articles 1621 - 1650 of 1778

Full-Text Articles in Chemistry

Metal Nanoparticle Synthesis By Photochemical Reduction With A High-Intensity Focused Laser Beam, Victoria K. Meader Jan 2019

Metal Nanoparticle Synthesis By Photochemical Reduction With A High-Intensity Focused Laser Beam, Victoria K. Meader

Theses and Dissertations

Colloidal, metallic nanoparticles have myriad applications, but they are most ideal when they are monodisperse, and demonstrate maximum catalytic utility when they are small (< 5 nm) and uncoated; because their surface area is accessible and maximized. Laser- assisted metal nanoparticle synthesis is a ‘green’ method that has become a topic of active research because it is able to produce uncoated or ‘naked’ products. The nanoparticles synthesized in this work were formed through the reduction of metal salts in aqueous solutions; but the reducing agent is an electron-dense microplasma generated by the laser pulse interacting with the media. Because no chemical reducing agents or stabilizers are needed, the products have no surfactants.

The underlying reaction mechanisms that drive this type of synthesis are generally understood, however, there is insufficient detail that would allow control over the formation of ultimate product morphologies and size distributions. The metals examined in this thesis are: gold, whose formation follows an autocatalytic rate law; and silver, whose formation follows a first-order rate law. Through my research, I was able to …


Improving Extraction Processes Of Crustacean Chitin Using Solid State Analytical Techniques, Fionn O'Fearghail, Michelle Giltrap, Christine O'Connor, Patrice Behan Jan 2019

Improving Extraction Processes Of Crustacean Chitin Using Solid State Analytical Techniques, Fionn O'Fearghail, Michelle Giltrap, Christine O'Connor, Patrice Behan

Articles

Solid state analytical techniques are becoming more widely used for the analysis of a range of organic products which demonstrate very poor solubility in both common organic and polar solvents and as such cannot be accurately characterised using solution based techniques. Primarily used as a secondary technique for qualitative analysis of insoluble intermediates and products in organic synthesis, 13C CP-MAS NMR can be utilised in tandem with a targeted extraction and clean up procedure for accurate quantitative analysis of insoluble bio-molecules of interest. Here solid state 13C CP-MAS NMR is utilised as the primary analytical technique in the characterisation of …


Investigation Of Coastal Sea-Fog Formation Using The Wibs (Wide Band Integrated Bioaerosol Sensor) Technique, Shane M. Daly, David O'Connor, David A. Healy, Stig Hellebust, Jovanna Arndt, Eoinj. Mcgillicuddy, Patrick Feeney, Michael Quirke, John C. Wenger, John R. Sodeau Jan 2019

Investigation Of Coastal Sea-Fog Formation Using The Wibs (Wide Band Integrated Bioaerosol Sensor) Technique, Shane M. Daly, David O'Connor, David A. Healy, Stig Hellebust, Jovanna Arndt, Eoinj. Mcgillicuddy, Patrick Feeney, Michael Quirke, John C. Wenger, John R. Sodeau

Articles

Abstract. A wideband integrated bioaerosol sensor (WIBS4) was deployed in Haulbowline Island, Cork Harbour, to detect fluorescence particles in real time during July and September 2011. A scanning mobility particle sizer (SMPS) was also installed providing sizing analysis of the particles over the 10–450nm range. During the campaign, multiple fog formation events occurred; they coincided with dramatic increases in the recorded fluorescent particle counts. The WIBS sizing and fluorescence intensity profiles indicated that the origin of the signals was potentially non-biological in nature (i.e. PBAPs, primary biological aerosol particles). Furthermore, the data did not support the presence of known fluorescing …


A Review: Thermal Stability Of Methylammonium Lead Halide Based Perovskite Solar Cells, Tanzila Tasnim Ava, Abdullah Al Mamun, Sylvain Marsillac, Gon Namkoong Jan 2019

A Review: Thermal Stability Of Methylammonium Lead Halide Based Perovskite Solar Cells, Tanzila Tasnim Ava, Abdullah Al Mamun, Sylvain Marsillac, Gon Namkoong

Electrical & Computer Engineering Faculty Publications

Perovskite solar cells have achieved photo-conversion efficiencies greater than 20%, making them a promising candidate as an emerging solar cell technology. While perovskite solar cells are expected to eventually compete with existing silicon-based solar cells on the market, their long-term stability has become a major bottleneck. In particular, perovskite films are found to be very sensitive to external factors such as air, UV light, light soaking, thermal stress and others. Among these stressors, light, oxygen and moisture-induced degradation can be slowed by integrating barrier or interface layers within the device architecture. However, the most representative perovskite absorber material, CH3 …


Metaproteomics Reveal That Rapid Perturbations In Organic Matter Prioritize Functional Restructuring Over Taxonomy In Western Arctic Ocean Microbiomes, Molly P. Mikan, H. Rodger Harvey, Emma Timmins-Schiffman, Michael Riffle, Damon H. May, Ian Salter, William S. Noble, Brook L. Nunn Jan 2019

Metaproteomics Reveal That Rapid Perturbations In Organic Matter Prioritize Functional Restructuring Over Taxonomy In Western Arctic Ocean Microbiomes, Molly P. Mikan, H. Rodger Harvey, Emma Timmins-Schiffman, Michael Riffle, Damon H. May, Ian Salter, William S. Noble, Brook L. Nunn

OES Faculty Publications

We examined metaproteome profiles from two Arctic microbiomes during 10-day shipboard incubations to directly track early functional and taxonomic responses to a simulated algal bloom and an oligotrophic control. Using a novel peptide-based enrichment analysis, significant changes (p-value < 0.01) in biological and molecular functions associated with carbon and nitrogen recycling were observed. Within the first day under both organic matter conditions, Bering Strait surface microbiomes increased protein synthesis, carbohydrate degradation, and cellular redox processes while decreasing C1 metabolism. Taxonomic assignments revealed that the core microbiome collectively responded to algal substrates by assimilating carbon before select taxa utilize and metabolize nitrogen intracellularly. Incubations of Chukchi Sea bottom water microbiomes showed similar, but delayed functional responses to identical treatments. Although 24 functional terms were shared between experimental treatments, the timing, and degree of the remaining responses were highly variable, showing that organic matter perturbation directs community functionality prior to alterations to the taxonomic distribution at the microbiome class level. The dynamic responses of these two oceanic microbial communities have important implications for timing and magnitude of responses to organic perturbations within the Arctic Ocean and how community-level functions may forecast biogeochemical gradients in oceans.


Organic Surfactants Protect Dissolved Aerosol Components Against Heterogeneous Oxidation, Jennifer A. Faust, Jonathan P.D. Abbatt Jan 2019

Organic Surfactants Protect Dissolved Aerosol Components Against Heterogeneous Oxidation, Jennifer A. Faust, Jonathan P.D. Abbatt

All Faculty Articles

Oxidative aging alters the composition of organic aerosols over time, in turn affecting the ability of aerosols to seed cloud formation and scatter solar radiation. Here we explore the heterogeneous photooxidation of model organic particles with and without a soluble surfactant coating. Tricarballylic acid (TCA), a proxy for α-pinene oxidation products, serves as a representative small organic solute. Sodium dodecyl sulfate (SDS) was selected as the representative soluble surfactant because its surface properties have been extensively characterized. A flow reactor and aerosol mass spectrometer were used to determine the second-order reaction rate constant (k = (1.9 ± 0.1) × …


Synthesis, Crystal Structure, And Characterization Of Two Heterometallic Transition Metal Citrate Complexes [M $=$ Co(Ii) And Cd(Ii)], Zeki̇ Kartal, Onur Şahi̇n, Abdülkeri̇m Yavuz Jan 2019

Synthesis, Crystal Structure, And Characterization Of Two Heterometallic Transition Metal Citrate Complexes [M $=$ Co(Ii) And Cd(Ii)], Zeki̇ Kartal, Onur Şahi̇n, Abdülkeri̇m Yavuz

Turkish Journal of Chemistry

In this study, two heterometallic transition metal complexes with the formulas [CoK$_{4}(\mu _{10}$-C$_{6}$H$_{5}$O$_{7})_{2}$]$_{n}$ and [CdK($\mu _{8}$-C$_{6}$H$_{5}$O$_{7})(\mu $-H$_{2}$O)(H$_{2}$O)]$_{n}$ were synthesized as crystalline compounds. The structures of\textbf{ }these crystalline metal complexes were characterized by their spectral analyses (FT-IR, FT-Raman, thermal analysis, magnetic properties, and single-crystal X-ray diffraction techniques). According to the spectral data of the new metal complexes obtained, both metal complexes are in the monoclinic crystal system and in the P2$_{1}$/c and P2$_{1}$ space groups, respectively. The asymmetric unit of the metal complex [CoK$_{4}(\mu _{10}$-C$_{6}$H$_{5}$O$_{7})_{2}$]$_{n}$ contains one Co(II) ion, two potassium cations, and one (C$_{6}$H$_{5}$O$_{7})$ citrate ligand, whereas that of the …


Reduced Graphene Oxide Supported Tin Oxide-Boron Oxide Flexible Paper Anodes For Li-Ion Batteries, Hi̇lal Köse, Şeyma Dombaycioğlu, Hatem Akbulut, Ali̇ Osman Aydin Jan 2019

Reduced Graphene Oxide Supported Tin Oxide-Boron Oxide Flexible Paper Anodes For Li-Ion Batteries, Hi̇lal Köse, Şeyma Dombaycioğlu, Hatem Akbulut, Ali̇ Osman Aydin

Turkish Journal of Chemistry

Freestanding tin oxide-boron oxide/reduced graphene oxide (SnO$_{2}$-B$_{2}$O$_{3}$/rGO) nanocomposite anode was produced for Li-ion cells. This binder-free flexible paper anode structure was fabricated by combining SnO$_{2}$-B$_{2}$O$_{3}$ composite and graphene oxide which were synthesized through the sol-gel method and Hummers' method, respectively. Field emission gun scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction were utilized to characterize anode materials. The Williamson-Hall (W-H) analysis was applied using XRD data to determine crystal size and strain of the lattice. Electrochemical tests, cyclic voltammetry, and electrochemical impedance spectroscopy measurements were performed to determine …


Modified Surface Relief Layer Created By Holographic Lithography: Application To Selective Sodium And Potassium Sensing, Sabad-E Gul, Luke O'Neill, John Cassidy, Izabela Naydenova Jan 2019

Modified Surface Relief Layer Created By Holographic Lithography: Application To Selective Sodium And Potassium Sensing, Sabad-E Gul, Luke O'Neill, John Cassidy, Izabela Naydenova

Articles

Point-of-care diagnostics will rely upon the development of low-cost, noncomplex, and easily integrated systems in order to examine biological samples such as blood and urine obtained from the patient. The development of metal ion sensors is a subject of significant relevance for physiological samples. The level of different blood electrolytes, mainly H+, Na+, K+ and Cl− is considerably used to monitor irregular physiologies. The particular challenge in biosensing, and in fact for any other sensor, is signal differentiation between non-specifically bound material and the specific detecting of the target molecule/ion. The biosensors described in this paper are fabricated by a …


Molecular Memory With Downstream Logic Processing Exemplified By Switchable And Self-Indicating Guest Capture And Release, Brian Daly, Thomas S. Moody, Allen J.M. Huxely, Chaoyi Yao, Benjamin Schazmann, Andre Alves-Areias, John F. Malone, H.Q. Nimal Gunaratne, Peter Nockemann, A. Prasanna De Silva Jan 2019

Molecular Memory With Downstream Logic Processing Exemplified By Switchable And Self-Indicating Guest Capture And Release, Brian Daly, Thomas S. Moody, Allen J.M. Huxely, Chaoyi Yao, Benjamin Schazmann, Andre Alves-Areias, John F. Malone, H.Q. Nimal Gunaratne, Peter Nockemann, A. Prasanna De Silva

Articles

Molecular-logic based computation (MLBC) has grown by accumulating many examples of combinational logic gates and a few sequential variants. In spite of many inspirations being available in biology, there are virtually no examples of MLBC in chemistry where sequential and combinational operations are integrated. Here we report a simple alcohol-ketone redox interconversion which switches a macrocycle between a large or small cavity, with erect aromatic walls which create a deep hydrophobic space or with collapsed walls respectively. Small aromatic guests can be captured or released in an all or none manner upon chemical command. During capture, the fluorescence of the …


Highly Selective Fluorimetric Turn-Off Detection Of Copper (Ii) By Two Different Mechanisms In Calix[4]Arene-Based Chemosensors And Chemodosimeters, Justine O'Sullivan, John Colleran, Brendan Twamley, Frances Heaney Jan 2019

Highly Selective Fluorimetric Turn-Off Detection Of Copper (Ii) By Two Different Mechanisms In Calix[4]Arene-Based Chemosensors And Chemodosimeters, Justine O'Sullivan, John Colleran, Brendan Twamley, Frances Heaney

Articles

Isoxazolo‐pyrene tethered calix[4]arenes selectively detect copper(II) ions without interference from related perchlorate ions. The fluorescence emission of the probes, synthesised by nitrile oxide alkyne cycloaddition, and characterised by spectroscopic and crystallographic data, is rapidly reduced by Cu(II) ions. Detection limits are in the micromolar or sub‐micromolar range (0.3–3.6 μM) based on a 1 : 1 sensor:analyte interaction. Voltammetric behaviour and 1H NMR data provide new insights into the sensing mechanism which is dependent on the calixarene substitution pattern. When the calixarene lower rim is fully substituted, Cu(II) detection occurs through a traditional chelation mechanism. In contrast, for calixarenes 1,3‐disubstituted on …


Nanomole Silver Detection In Chloride-Free Phosphate Buffer Using Platinum And Gold Micro- And Nanoelectrodes, Prabhakar Sidambaram, John Colleran Jan 2019

Nanomole Silver Detection In Chloride-Free Phosphate Buffer Using Platinum And Gold Micro- And Nanoelectrodes, Prabhakar Sidambaram, John Colleran

Articles

The electrochemical determination of ultra-low concentrations of silver requires reliable, reproducible measurements using sensitive analytical techniques. To date, the electrochemical determination of silver in biological buffers and pH neutral media has not been successful in terms of reproducibility. In this work, we report on the determination of ultra-low concentrations of silver in chloride-free phosphate buffer solution (PB, pH 7.4). Detection was conducted at gold and platinum micro and nanoelectrodes using anodic stripping voltammetry (ASV). The micro and nanoelectrodes were fabricated using a Sutter P-2000 laser puller, with physical and electrochemical characterization revealing flat disk-shaped working surfaces of 10–15 μm (microelectrode) …


Evaluating Methods Of Obtaining Male Pheromone From Hymenochirus Sp. Using Analytical Chemistry, Vincent Wing-Kun Leung Jan 2019

Evaluating Methods Of Obtaining Male Pheromone From Hymenochirus Sp. Using Analytical Chemistry, Vincent Wing-Kun Leung

University of the Pacific Theses and Dissertations

Male Hymenochirus sp. frogs are known to release pheromone that attracts females of the same species. Four methods for collecting secretions containing pheromone in Hymenochirus sp. were tested: norepinephrine injection, gonadotropin-releasing hormone injection, homogenization of gland tissue, and electrostimulation of the skin over the breeding gland area. The samples collected were analyzed using high-performance liquid chromatography (HPLC) and mass spectrometry. The HPLC chromatograph for the male norepinephrine sample contained a peak at 6.4 min that was not in the female norepinephrine sample HPLC chromatograph. The male norepinephrine sample mass spectrum had a peak of m/z 292.0 not in the female …


Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems, Kyle John Covert Jan 2019

Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems, Kyle John Covert

University of the Pacific Theses and Dissertations

Two small combustion systems, methyl hydroperoxide (CH3OOH) and 2-propanol ((CH3)2CHOH), were studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO), which combines photoelectron spectroscopy and photoionization mass spectrometry to detect coincident photoelectron-photoion pairs. In the photon energy range of 11.4–14.0 eV, energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions. The lowest-energy dissociation channel is the formation of the cation of the smallest “QOOH” radical, CH2OOH+. A statistical rate model fitted to the …


Development And Characterization Of Ldv Peptide Targeted Nanocarriers For Paclitaxel Delivery: A Comparative Study Of Micelles, Liposomes And Solid Lipid Nanoparticles, Poonam Dattani Jan 2019

Development And Characterization Of Ldv Peptide Targeted Nanocarriers For Paclitaxel Delivery: A Comparative Study Of Micelles, Liposomes And Solid Lipid Nanoparticles, Poonam Dattani

University of the Pacific Theses and Dissertations

Nanocarriers have been established as delivery vehicles to target cancer tumors. However, premature drug leakage is one of the major reasons for inefficient drug delivery of nanocarriers to the tumor. Drug diffusion out of the nanocarriers or destabilization of drug loaded nanocarriers by physiological interactions with blood cells, serum proteins, and cell membranes upon systemic administration contribute to premature drug release. In this study, targeted micelles, liposomes and solid lipid nanoparticles (SLNs) of similar composition were prepared and characterized to compare physicochemical characteristics, in vitro stability, in vitro release rates in release media and in vivo performance. Peptide Amphiphiles (PAs) …


Approaches To The Search Of Platinum Anticancer Agents: Derivatizing Current Drugs And Incorporating Hdac Inhibition, Chao Feng Jan 2019

Approaches To The Search Of Platinum Anticancer Agents: Derivatizing Current Drugs And Incorporating Hdac Inhibition, Chao Feng

University of the Pacific Theses and Dissertations

Platinum-based anticancer drugs, such as cisplatin, carboplatin, and oxaliplatin, have been approved for clinical use worldwide for decades. Despite their enormous success, their widespread application is hindered by either cross-resistance or toxic side effects, including nephrotoxicity and neurotoxicity. The need to overcome these drawbacks has stimulated the search for new platinum-based drugs.

This dissertation will start with the accidental discovery of cisplatin, followed by an introduction of other platinum-based anticancer agents, including the action mechanism, general structures, and development history. Picoplatin is a newer generation of platinum-based anticancer agent. The bulky 2-methylpyridine as a non-leaving group on picoplatin could reduce …


Exploring The Molecular Origin Of Jet Fuel Thermal Oxidative Deposition Through Statistical Analysis Of Mass Spectral Data And Pyrolysis Gas Chromatography/Mass Spectrometry Of Deposits, Krege Matthew Christison Jan 2019

Exploring The Molecular Origin Of Jet Fuel Thermal Oxidative Deposition Through Statistical Analysis Of Mass Spectral Data And Pyrolysis Gas Chromatography/Mass Spectrometry Of Deposits, Krege Matthew Christison

University of the Pacific Theses and Dissertations

ASTM D3241 (Standard Test Method for Thermal Oxidation Stability of Aviation Turbine Fuels) measures the thermal oxidative stability of jet fuels under elevated temperature and pressure conditions. When jet fuels fail ASTM D3241, either at the refinery or in the distribution system, there can be supply disruptions and financial losses. Understanding the causes of poor thermal oxidative stability in jet fuels could help prevent or mitigate issues. In order to develop a deeper understanding of the molecular precursors that lead to ASTM D3241 failures, a number of analytical methodologies and data treatment techniques have been developed, applied, and reported here. …


I3: Isomerization Of Isomer Ions, Krisztián Gabor Torma Jan 2019

I3: Isomerization Of Isomer Ions, Krisztián Gabor Torma

University of the Pacific Theses and Dissertations

Photoelectron Photoion Coincidence (PEPICO) spectroscopy is a robust tool for elucidating complex unimolecular dissociation mechanisms and for determining thermochemical and kinetic data of gas-phase ion dissociations with high accuracy. In this work, the dissociative photoionization of two sets of isomeric systems were analyzed with PEPICO: 1) C7H7+ ions of toluene (Tol) and 1,3,5-cycloheptatriene (CHT), and 2) two butyl alcohol isomers, 1-butanol and isobutanol. Threshold dissociative photoionization data on these four molecules of interest were collected on the imaging PEPICO apparatus at the VUV beamline of the Swiss Light Source. Data analysis was aided by ab initio calculations and Rice-Ramsperger-Kassel-Marcus (RRKM) …


On-Road Remote Sensing Of Automobile Emissions In The Chicago Area: Fall 2018, Gary A. Bishop Jan 2019

On-Road Remote Sensing Of Automobile Emissions In The Chicago Area: Fall 2018, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.


Measuring Emissions From The On-Road Vehicle Fleet In West Los Angeles, Gary A. Bishop Jan 2019

Measuring Emissions From The On-Road Vehicle Fleet In West Los Angeles, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.


Three Decades Of On-Road Mobile Source Emissions Reductions In South Los Angeles, Gary A. Bishop Jan 2019

Three Decades Of On-Road Mobile Source Emissions Reductions In South Los Angeles, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

In May of 2018, the University of Denver repeated on-road optical remote sensing measurements at two locations in Lynwood, CA. Lynwood area vehicle tailpipe emissions were first surveyed in 1989 and 1991 because the area suffered with a large number of carbon monoxide (CO) air quality violations. These new measurements allow for the estimation of fuel specific CO and total hydrocarbon (HC) emissions reductions, changes in the longevity of emission-control components, and the prevalence of high emitters in the current fleet.

Since 1989 CO emissions decreased approximately factors of 10 (120 ± 8 to 12.3 ± 0.2 gCO/kg of fuel) …


Raman Spectroscopy As A Potential Tool For Label Free Therapeutic Drug Monitoring In Human Serum: The Case Of Busulfan And Methotrexate, Drishya Parachalil, Franck Bonnier, Deirdre Commerford, Igor Chourpa, Jennifer Mcintyre, Hugh Byrne Jan 2019

Raman Spectroscopy As A Potential Tool For Label Free Therapeutic Drug Monitoring In Human Serum: The Case Of Busulfan And Methotrexate, Drishya Parachalil, Franck Bonnier, Deirdre Commerford, Igor Chourpa, Jennifer Mcintyre, Hugh Byrne

Articles

A methodology is proposed, based on Raman spectroscopy coupled with multivariate analysis, to determine the Limit of Detection (LOD) and Limit of Quantification (LOQ) for therapeutic drug monitoring in human serum, using the examples of Busulfan, a cell cycle non-specific alkylating antineoplastic agent, and, Methotrexate, a chemotherapeutic agent and immune system suppressant. In this study, ultrafiltration is employed to fractionate spiked human pooled serum to efficiently recover the drug in the filtrate prior to performing Raman analysis. The drug concentration ranges were chosen to encompass the recommended therapeutic ranges and toxic levels in patients. Raman spectra were collected from the …


On The Use Of Vibrational Spectroscopy And Scanning Electron Microscopy To Study Phenolic Extractability Of Cooperage Byproducts In Wine, Berta Baca‑Bocanegra, Julio Nogales‑Bueno, Brian Gorey, Francisco José Heredia, Hugh Byrne, José Miguel Hernández‑Hierro Jan 2019

On The Use Of Vibrational Spectroscopy And Scanning Electron Microscopy To Study Phenolic Extractability Of Cooperage Byproducts In Wine, Berta Baca‑Bocanegra, Julio Nogales‑Bueno, Brian Gorey, Francisco José Heredia, Hugh Byrne, José Miguel Hernández‑Hierro

Articles

Wood is an important source of phenolic compounds, which can be transferred to wine during aging process, improving its properties, from an organoleptic point of view. Therefore, understanding and optimizing the extractability of phenolic compounds from wood are crucial in the oenological field. The structural composition of oak wood samples has been evaluated using Raman and attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopies, and their main spectral features have been linked to phenolic compound extractabilities, as measured by classic chemical analyses. To support the analysis, microscopic images of the samples were also recorded using scanning electron microscopy (SEM). The …


Solvent Effects And Charge Transfer States In Organic Photovoltaics, Kangmin Liu Jan 2019

Solvent Effects And Charge Transfer States In Organic Photovoltaics, Kangmin Liu

Wayne State University Dissertations

Due to their various advantages, including lightweight, flexible, and cheap manufacturing, organic photovoltaic materials have gained enormous research interest. Over nearly two decades, the power conversion efficiency of organic solar devices has increased dramatically. However, it is still low compared to traditional inorganic semiconductors. In order to improve efficiency, a better understanding of the basic thermodynamic properties of the light-to-electricity power conversion process is needed. One nontrivial aspect of organic solar cells is the low dielectric constant, which leads to tightly-bound excitons upon vertical excitations. The separation of electron-hole pairs requires a larger driving force to overcome the Coulombic binding …


Functional Characterization Of Accessory Proteins And Novel Activities In Direct And Indirect Trna Aminoacylation, Udumbara Menike Rathnayake Jan 2019

Functional Characterization Of Accessory Proteins And Novel Activities In Direct And Indirect Trna Aminoacylation, Udumbara Menike Rathnayake

Wayne State University Dissertations

Indirect tRNA aminoacylation is essential for most bacteria and archaea, particularly when these species do not have genes encoding asparaginyl- and/or glutaminyl-tRNA synthetase (AsnRS and GlnRS). In the absence of AsnRS, the first step in Asn-tRNAAsn synthesis involves misacylation of tRNAAsn with aspartate to produce Asp-tRNAAsn; this reaction is catalyzed by a non-discriminating aspartyl-tRNA synthetase (ND-AspRS). Subsequently, in bacteria, an amidotransferase called GatCAB converts Asp-tRNAAsn to Asn-tRNAAsn. An analogous, two-step processes exist to produce Gln-tRNAGln. In this case, a non-discriminating glutamyl-tRNA synthetase (ND-GluRS) misacylates tRNAGln to produce Glu-tRNAGln, which is then converted to Gln-tRNAGln by GatCAB. The central hub of …


Ionic Liquid Based Polymer Gel Electrolytes For Use With Germanium Thin Film Anodes In Lithium Ion Batteries, Louise M. Mcgrath, John Jones, Edwin Carey, James F. Rohan Jan 2019

Ionic Liquid Based Polymer Gel Electrolytes For Use With Germanium Thin Film Anodes In Lithium Ion Batteries, Louise M. Mcgrath, John Jones, Edwin Carey, James F. Rohan

Articles

Thermally stable, flexible polymer gel electrolytes with high ionic conductivity are prepared by mixing the ionic liquid 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (C4mpyrTFSI), LiTFSI and poly(vinylidene difluoride‐co‐hexafluoropropylene (PVDF‐HFP). FT‐IR and Raman spectroscopy show that an amorphous film is obtained for high (60 %) C4mpyrTFSI contents. Thermogravimetric analysis (TGA) confirms that the polymer gels are stable below ∼300 °C in both nitrogen and air environments. Ionic conductivity of 1.9×10−3 S cm−2 at room temperature is achieved for the 60 % ionic liquid loaded gel. Germanium (Ge) anodes maintain a coulombic efficiency above 95 % after 90 cycles in …


Fluorescence Quenching-Based Mechanism For Determination Of Hypochlorite By Coumarin-Derived Sensors, Karolina Starzak, Arkadiusz Matwijczuk, Bernadette Creaven, Alicja Matwijczuk, Sławomir Wybraniec, Dariusz Karcz Jan 2019

Fluorescence Quenching-Based Mechanism For Determination Of Hypochlorite By Coumarin-Derived Sensors, Karolina Starzak, Arkadiusz Matwijczuk, Bernadette Creaven, Alicja Matwijczuk, Sławomir Wybraniec, Dariusz Karcz

Articles

A fluorescence quenching-based mechanism for the determination of hypochlorite was proposed based on spectroscopic and chromatographic studies on the hypochlorite-sensing potency of three structurally similar and highly fluorescent coumarins. The mode of action was found to rely upon a chlorination of the coumarin-based probes resulting from their reaction with sodium hypochlorite. Importantly, the formation of chlorinated derivatives was accompanied by a linear decrease in the fluorescence intensities of the probes tested. The results obtained suggest the applicability of a coumarin-dependent hypochlorite recognition mechanism for the detection of, as well as for quantitative determination of, hypochlorite species in vitro.


Spheroid-3d And Monolayer-2d Intestinal Electrochemical Biosensor For Toxicity/Viability Testing: Applications In Drug Screening, Food Safety, And Environmental Pollutant Analysis, Evangelia Flampouri, Shahzad Imar, Kieran O'Connell, Baljit Singh Jan 2019

Spheroid-3d And Monolayer-2d Intestinal Electrochemical Biosensor For Toxicity/Viability Testing: Applications In Drug Screening, Food Safety, And Environmental Pollutant Analysis, Evangelia Flampouri, Shahzad Imar, Kieran O'Connell, Baljit Singh

Articles

The rise of three-dimensional cell culture systems that provide in vivo-like environments for pharmaco-toxicological models has prompted the need for simple and robust viability assays suitable for complex cell architectural structures. This study addresses that challenge with the development of an in vitro enzyme based electrochemical sensor for viability/cytotoxicity assessment of two-dimensional (2D) monolayer and three-dimensional (3D) spheroid culture formats. The biosensor measures the cell viability/toxicity via electrochemical monitoring of the enzymatic activity of nonspecific esterases of viable cells, through the hydrolysis of 1-naphthyl acetate to 1-naphthol. The proposed sensor demonstrated strong correlation (r = 0.979) with viable …


Electrochemical Enzyme-Linked Immunosorbent Assay (E-Elisa) For Parasitic Nematode: Ostertagia Ostertagi (Brown Stomach Worm) Infections In Dairy Cattle, Baljit Singh, Evangelia Flampouri, Eithne Dempsey Jan 2019

Electrochemical Enzyme-Linked Immunosorbent Assay (E-Elisa) For Parasitic Nematode: Ostertagia Ostertagi (Brown Stomach Worm) Infections In Dairy Cattle, Baljit Singh, Evangelia Flampouri, Eithne Dempsey

Articles

A sensitive electrochemical immunoassay (e-ELISA) has been developed for the detection of the gastrointestinal parasitic nematode Ostertagia ostertagi (brown stomach worm) in infected and control serum samples. An antigen-indirect immunoassay format was employed to detect the presence of O. ostertagi antibodies, coupled with an anti-species monoclonal horseradish peroxidase (HRP) conjugate. ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) and TMB (3,3',5,5'-tetramethylbenzidine/hydrogen peroxide) were investigated as both chromogenic visualising reagents for optical ELISA and electroactive substrates for electrochemical ELISA in the HRP catalysed oxidation reaction. Coulometry was applied for the detection of O. ostertagi antibodies (via TMB electrochemistry) and compared with the commercial optical ELISA (ABTS …


Compound-Specific Isotope Analysis Of Amino Acids In Biological Tissues: Applications In Forensic Entomology, Food Authentication And Soft-Biometrics In Humans, Mayara Patricia Viana De Matos Jan 2019

Compound-Specific Isotope Analysis Of Amino Acids In Biological Tissues: Applications In Forensic Entomology, Food Authentication And Soft-Biometrics In Humans, Mayara Patricia Viana De Matos

Graduate Theses, Dissertations, and Problem Reports (ETD)

In this work we demonstrate the power of compound-specific isotope analysis (CSIA) to analyze proteinaceous biological materials in three distinct forensic applications, including: 1) linking necrophagous blow flies in different life stages to their primary carrion diet; 2) identifying the harvesting area of oysters for food authentication purposes; and 3) the ability to predict biometric traits about humans from their hair.

In the first application, we measured the amino-acid-level fractionation that occurs at each major life stage of Calliphora vicina (Robineau-Desvoidy) (Diptera: Calliphoridae) blow flies. Adult blow flies oviposited on raw pork muscle, beef muscle, or chicken liver. Larvae, pupae …