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Articles 61 - 86 of 86
Full-Text Articles in Physical Sciences and Mathematics
High Voltage Dye-Sensitized Solar Cells And Molecular Photocatalysis For Co2 Reduction, Roberta Ramalho Rodrigues
High Voltage Dye-Sensitized Solar Cells And Molecular Photocatalysis For Co2 Reduction, Roberta Ramalho Rodrigues
Electronic Theses and Dissertations
The development of high voltage solar cells is an attractive way to use sunlight to power electrocatalysts for water oxidation, electrocatalysts for CO2 reduction, and consumer electronics. Through careful molecular dye engineering and redox shuttle pairing, our group has reported a single-junction dye-sensitized solar cell (DSC) employing, for the first time, an iron redox mediator (Fe(bpy)33+/2+) in conjunction with a novel wide band gap dye (RR9). This system generates a high photovoltage of 1.42 V. To the best of our knowledge, this system is the highest photovoltage achieved by a single-junction DSC device without metal oxide doping. The RR9/Fe(bpy)33+/2+ redox …
Application Of Analytical Techniques In Food Product Development, Sonali R. Pandey
Application Of Analytical Techniques In Food Product Development, Sonali R. Pandey
Electronic Theses and Dissertations
Products are analyzed in major sectors of food industry to meet regulatory standards, food safety, quality control, and research and development. Analytical and extraction techniques have been applied for simultaneous investigation of multiple product characteristics. Food analysis faces critical challenges due to the complex composition of food, leading to matrix effects that result in loss of accuracy and reliability. The analytical techniques require an efficient sample preparation to avoid or minimize matrix effects. Solid-phase extraction has been widely used to address this issue. In this dissertation, the aim is to apply analytical techniques in food product development. To accomplish this, …
Chemometric Applications In Fire Debris Analysis: Likelihood Ratios From Naive Bayes And Frequency Of Component And Pyrolysis Product Occurrence, Anuradha Akmeemana
Chemometric Applications In Fire Debris Analysis: Likelihood Ratios From Naive Bayes And Frequency Of Component And Pyrolysis Product Occurrence, Anuradha Akmeemana
Electronic Theses and Dissertations
One of the major challenges in fire investigation is the determination of the cause of fire. The fire can be accidental or intentional. The determination of ignitable liquid residue (ILR) from fire debris helps the process and this process is called fire debris analysis in forensic science. This is one of the most complex areas in the field of forensics because of the evaporation of the ILR from the debris and the interference of the substrate matrix with the ILR if present. In the present, the final decisions in fire debris analysis are based on categorical statements and it only …
Metastable-State Photoacids: Synthesis, Properties, And Applications, Parth Patel
Metastable-State Photoacids: Synthesis, Properties, And Applications, Parth Patel
Electronic Theses and Dissertations
Reversible photochromic compounds have the ability to reversibly change its color when it absorbs photons of a particular wavelength. This process of color change is a consequence of structural changes within the compound, such as cis-trans photo-isomerization. Some examples of photochromic compounds are spiropyrans, spirooxazines, diarylethenes and azobenzenes. These compounds have been extensively studied for decades, and are used in various applications such as biomedicine, chemical sensors and harvesting solar energy. However, majority of photochromic compounds are initially activated by ultraviolet (UV) light. The use of UV light is harmful for biological applications and photo-degrade the compound over repeated use. …
The Characterization Of Condom Lubricants And Personal Hygiene Products Using Dart-Tofms And Gc- Ms And The Investigation Of Gold Nanoparticle Behavior In Water And The Interaction With Blood Serum Proteins, Yasmine Moustafa
Electronic Theses and Dissertations
This dissertation is divided into two independent research projects. First, condom lubricants, sexual lubricants, and personal hygiene products (PHPs) were studied using direct analysis in real time-time-of-flight-mass spectrometry (DART-TOFMS) and gas chromatography-mass spectrometry (GC-MS). The purpose addressed the concern of perpetrators resorting to new tactics, i.e. using condoms to remove seminal fluid that could provide a DNA link to a suspect, leading to the need of the consideration of condom lubricants as pieces of sexual assault evidence. Due to condom lubricants having a chemical composition resembling PHPs, the investigation of both sample groups was analyzed to prevent false positives. Although …
The Evaluation Of Classifier Performance On The Forensic Analysis Of Fire Debris And The Expansion Of The Substrate Database, Alyssa Allen
The Evaluation Of Classifier Performance On The Forensic Analysis Of Fire Debris And The Expansion Of The Substrate Database, Alyssa Allen
Electronic Theses and Dissertations
The current protocols in fire debris analysis rely on ignitable liquid pattern recognition and the identification of target compounds. These practices allow fire debris analysts to determine whether a sample contains or is absent of ignitable liquid residue and to classify that type of ignitable liquid based upon subjective thresholds. A statistical approach using computationally mixed datasets was devised in this research to generate an objective approach to the classification of fire debris samples and to determine error rates. Quadratic, linear, and partial least squares linear discriminant analysis (QDA, LDA, and PLS-DA) models were developed and evaluated to determine the …
Advanced Analysis Of Compounds Of Toxicological Importance By Ice Concentration Linked With Extractive Stirrer (Icecles) Gc-Ms And Rp-Hplc-Esi-Ms-Ms, Joseph K. Dzisam
Advanced Analysis Of Compounds Of Toxicological Importance By Ice Concentration Linked With Extractive Stirrer (Icecles) Gc-Ms And Rp-Hplc-Esi-Ms-Ms, Joseph K. Dzisam
Electronic Theses and Dissertations
Cyanide and nitrosoamines (NAs) are ubiquitous compounds, found in our food and water, either by natural process or through man-made activities. The toxicity of cyanide is exerted by its ability to inhibit metalloenzymes such as cytochrome c oxidase, causing concomitant cascades of biochemical effects such as lactic acidosis, inhibition of ATP production, respiratory seizure, and potential death. Nitrosoamines, on the other hand, undergo biotransformation (metabolic activation in cytochrome P450) in the body to produce unstable intermediates that alkylate DNA, causing mutations, and leading to carcinogenesis. In order to further the advancement of a promising cyanide, cobinamide (Cbi), an LC-MS-MS method …
Organic Sensitizers For High Efficiency Dye-Sensitized Solar Cells, Adithya Peddapuram
Organic Sensitizers For High Efficiency Dye-Sensitized Solar Cells, Adithya Peddapuram
Electronic Theses and Dissertations
After the industrial revolution in 19th-century energy, demand has increased exponentially. Relying on fossil fuels long term is not a good option due to their non-renewable nature and concerns about burning fossil fuels raising carbon dioxide levels in atmosphere. This dissertation describes, utilizing sunlight for electricity production with dye-sensitized solar cells (DSCs). DSCs are an attractive solar technology due to processing advantages over traditional solar cells. To improve the stability of DSCs, strong surface binding dyes are important. This work studies the dual anchor dual donor (DD-π-AA) dye framework with various donors (electron rich π-systems) and π-bridges (electron neutral π-systems). …
Near-Infrared High Efficiency Organic Dye Sensitized Solar Cells (Dscs) And Biological Fluorescent Imaging Dyes, Yanbing Zhang
Near-Infrared High Efficiency Organic Dye Sensitized Solar Cells (Dscs) And Biological Fluorescent Imaging Dyes, Yanbing Zhang
Electronic Theses and Dissertations
With the energy consumption increase every year, the non-renewable energy sources such as fossil fuels, natural gas, and coal will not sustain forever. In this case, searching for a way to develop a renewable energy source is an emergency. For decades, dye-sensitized solar cells (DSCs) have received intensive attention due to their high power conversion efficiency and low material cost. This dissertation describes efforts to design and synthesize near-infrared organic dyes to apply to two systems: first, for use in the improvement of DSCs by the optimization of electron rich components such as ullazine and cross-conjugated -bridges to increase photon-to-electricity …
Electrochemical Studies Involving Co2 Reduction With Rhenium-Based Catalysts And For Guanosine Monophosphate Oxidation, Kayla A. Milano
Electrochemical Studies Involving Co2 Reduction With Rhenium-Based Catalysts And For Guanosine Monophosphate Oxidation, Kayla A. Milano
Electronic Theses and Dissertations
The following chapter of this thesis will cover the oxidation of guanine monophosphate (GMP). GMP has been linked to numerous conditions when it is oxidized or damaged. There have been two oxidation pathways suggested in association to the oxidation of GMP: EPT and MS-EPT. The ideal conditions for GMP’s oxidation is still be studied and collected. The study focuses on the acetate versus phosphate buffer, varying base concentration in phosphate buffer, and the varying concentration of ruthenium complex, a redox mediator.
Theranostics Based On Linear Dendritic Block Copolymers, Jon Williams
Theranostics Based On Linear Dendritic Block Copolymers, Jon Williams
Electronic Theses and Dissertations
When combining imaging and therapeutic motifs, known as theranostics, amphiphilic diblock copolymers have a strong precedent of success. These polymers can self-assemble into a variety of morphologies that are known to concentrate in areas of inflammation such as tumors. However, prediction of size and morphology from polymer structure still remains an open challenge. Another system with promise of therapeutic efficacy are tree-like struc- tures known as dendrimers, such as poly(amidoamine) (PAMAM) and bis-(hydroxymethyl) propionic acid (bMPA), which can uptake drugs and dyes into their branches. It is desireable to combine these two motifs, using linear-dendritic block copolymers (LDBCs). These represent …
Physical And Chemical Trace Evidence From 3d-Printed Firearms, And Use Of A Quadcopter For Targeted Sampling Of Gaseous Mercury In The Atmosphere, Oscar Beauchamp Black
Physical And Chemical Trace Evidence From 3d-Printed Firearms, And Use Of A Quadcopter For Targeted Sampling Of Gaseous Mercury In The Atmosphere, Oscar Beauchamp Black
Electronic Theses and Dissertations
My forensic research resulted in the first peer-reviepaper to address the forensic challenges presented by 3D-printed polymer firearms. The work involved a systematic approach to the analysis of evidence stemming from 3D-printed firearms filling a critical void in current forensic knowledge. We used DART-MS to characterize the polymer evidence left behind by 3D-printed firearms as well as an evaluation of pre-existing firearm and toolmark techniques and fingerprint analysis. We demonstrated that 3D-printed firearms leave behind characteristic polymer residue on cartridge cases bullets and the receiving surface which can be identified using DART-MS. The culmination of the work includes a database …
Probing Atypical Noncovalent Interactions Using Electronic Structure Theory, Katelyn Mae Dreux
Probing Atypical Noncovalent Interactions Using Electronic Structure Theory, Katelyn Mae Dreux
Electronic Theses and Dissertations
Some of the most important topics in modern chemistry involve noncovalent interactions in a variety of ways, from pharmacological processes to materials design. Due to the comparatively weak nature of these interactions, they can be difficult to investigate experimentally. Beyond what might be considered the ‘typical’ noncovalent interactions such as hydrogen bonding or London dispersion, there are less well known noncovalent interactions such as coordinate covalent, dihydrogen, and nonconventional hydrogen bonding, which have been the focus of much of this research. Through the use of electronic structure theory, fundamental information about the structure, energetics, and molecular properties of noncovalently bound …
Characterization Of Hydrogen Bonding, Halogen Bonding And Argyrophilic Interactions Using Computational Modeling, Sarah Nicole Arradondo
Characterization Of Hydrogen Bonding, Halogen Bonding And Argyrophilic Interactions Using Computational Modeling, Sarah Nicole Arradondo
Electronic Theses and Dissertations
Non-covalent interactions govern multiple important chemical processes throughout nature from those within the human body to the complex environment of the atmosphere. Quantum mechanical electronic structure modeling of these relatively weak interactions can provide molecular level insight that can further our understanding of specific macroscopic properties. In the present work different non-covalent interactions are computationally evaluated within four systems. A small prototypical hydrogen bonded system and the various structural motifs that promoted proton transfer within concentrated acid and water clusters are characterized with sophisticated wavefunction based methods and large robust basis sets in order to accurately predict the structures energies …
Effects Of Halogen Bonding And Nir Tuning Of Dyes For Dye-Sensitized Solar Cells, Alexandra Baumann
Effects Of Halogen Bonding And Nir Tuning Of Dyes For Dye-Sensitized Solar Cells, Alexandra Baumann
Electronic Theses and Dissertations
With current energy demands being met through the utilization of energy sources such as petroleum, natural gas, and coal, the non-renewable nature of these sources will eventually approach depletion as world wide energy consumption increases yearly. As a result the need for a renewable energy alternative has become imminent. One appealing alternative that has gained considerable attention since its development due to a low cost and a high solar to electric conversion efficiency are dye-sensitized solar cells (DSCs). This dissertation describes efforts to design and synthesize improved organic dyes utilizing three analogous methods: first, through decreasing non-productive pathways such as …
Electro- And Photocatalytic Carbon Dioxide Reduction And Thermal Isomerization Of Highly Strained Tricyclocompounds, Weiwei Yang
Electro- And Photocatalytic Carbon Dioxide Reduction And Thermal Isomerization Of Highly Strained Tricyclocompounds, Weiwei Yang
Electronic Theses and Dissertations
Anthracene-bridged dinuclear rhenium complexes are reported for electrocatalytic and photocatalytic carbon dioxide (CO2) reduction to carbon monoxide (CO). Related by hindered rotation of each rhenium active site to either side of the anthracene bridge cis and trans conformers have been isolated and characterized. Electrochemical studies reveal distinct mechanisms whereby the cis conformer operates via cooperative bimetallic CO2 activation and conversion and the trans conformer reduces CO2 through well-established single-site and bimolecular pathways analogous to Re(bpy)(CO)3Cl. Higher turnover frequencies are observed for the cis conformer (35.3 s−1) relative to the trans conformer (22.9 s−1) with both outperforming Re(bpy)(CO)3Cl (11.1 s−1). Photocatalytic …
Evaluating Green Solvents And Techniques In Extraction Methods, Shanmugapriya Dharmarajan
Evaluating Green Solvents And Techniques In Extraction Methods, Shanmugapriya Dharmarajan
Electronic Theses and Dissertations
Of all analytical techniques, extraction is a huge solvent-consuming process that could adversely impact the environment. Use of petroleum-based solvents for extraction of oilseeds is still a common practice, despite the potential fire hazard and the toxic water pollution. The rising awareness of chemical activities created immense need for sustainable development schemes and strategies that should address the environmental impact without compromising the yield. In the course of developing green extraction techniques, automation, alternative solvents, and selective extractions are the growing trend. This dissertation aligns with that progress by surveying green solvents, comparing their performance during oil extraction, examining a …
Investigating Anions And Hydrophobicity Of Deep Eutectic Solvents By Experiment And Computational Simulation, Amos Kwabena Dwamena
Investigating Anions And Hydrophobicity Of Deep Eutectic Solvents By Experiment And Computational Simulation, Amos Kwabena Dwamena
Electronic Theses and Dissertations
Deep eutectic solvents are a new generation of ionic liquid-like solvents formed by combining hydrogen bond acceptor with hydrogen bond donor which result in the depression of the melting point of the solvent. Like ionic liquids, anions play a critical role in tuning the polarity, physicochemical properties, and thermodynamic behavior of deep eutectic solvent (DES). Choline chloride is the most widely used quaternary ammonium salt (QAS) in the literature and has remarkable advantages from reduced cost to low toxicity and volatility. Choline bromide and choline iodide are other QAS that have not been used often for DES synthesis and applications, …
Design, Synthesis And Biological Screening Of Novel Cucs-Inspired Estrone Analogs Towards Treatment Of Pancreatic Adenocarcinoma, Khaled Alseud
Design, Synthesis And Biological Screening Of Novel Cucs-Inspired Estrone Analogs Towards Treatment Of Pancreatic Adenocarcinoma, Khaled Alseud
Electronic Theses and Dissertations
Pancreatic cancer is currently the fourth most deadly type of cancer globally. It is expected to become the second by 2030, due to its poor prognosis and its resistance to the current standard treatment, Gemcitabine. Moreover, the survival rate after treatment is low compared to other cancer types, which suggests an urgent need for new potent and safe treatment agents. Recently, the triterpenoid, cucurbitacin, has shown promising antiproliferative activity against human pancreatic cancer cells in a dose- and timedependent manner, and decreased pancreatic tumor size in combination with gemcitabine in vivo. However, the use of cucurbitacin in clinical studies has …
In-Silico Design And Synthesis Of Selective Estrogen Receptor Modulators Targeting Ovarian Cancer, John Apraku
In-Silico Design And Synthesis Of Selective Estrogen Receptor Modulators Targeting Ovarian Cancer, John Apraku
Electronic Theses and Dissertations
The established records of the safety of Ormeloxifene along with its favorable bioavailability and ability to inhibit rapid cell proliferation in the endometrium during embryonic implantation has made it one of the best drug candidates for controlling undesirable rapid cell growth such as endometriosis and cancerous tumor conditions. Recent studies have confirmed the effectiveness of Ormeloxifene to suppress and inhibit epithelial-mesenchymal transition process as evidenced by repression of N-cadherin, slug, snail, vimentin, MMPs, β-catenin/TCF-4 transcriptional activity and induce the expression of pGSK3b. Recently conducted studies have revealed the dynamic binding of ormeloxifene with β-catenin, GSK3b, CDK4, and other downstream EGFR. …
Intramoleculer Hydrogen Bonding In Epoxide, Thiirane, Aziridine And Phosphirane Containing Cyclopentanols, Ben Edward Smith
Intramoleculer Hydrogen Bonding In Epoxide, Thiirane, Aziridine And Phosphirane Containing Cyclopentanols, Ben Edward Smith
Electronic Theses and Dissertations
A recent computational analysis of the stabilizing intramolecular OH· · · O contact in 1,2-dialkyl-2,3-epoxycyclopentanol diastereomers has been extended to thiiriane, aziridine and phosphirane analogues. Density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2) and CCSD(T) coupled-cluster computations with simple methyl and ethyl substituents indicate that electronic energies of the cis isomers are lowered by roughly 3 to 4 kcal mol−1 when the OH group of these cyclopentanol systems forms an intramolecular contact with the O, S, N or P atom on the adjacent carbon. The results also suggest that S and P can participate in these stabilizing intramolecular interactions …
Ni And Au Transition Metal Complexes In The Photocatalytic Co2 Reduction Reaction, Shakeyia Davis
Ni And Au Transition Metal Complexes In The Photocatalytic Co2 Reduction Reaction, Shakeyia Davis
Electronic Theses and Dissertations
The production of renewable fuels by the conversion of solar energy into chemical energy is a challenge. Photocatalytic and electrocatalytic conversion of CO2 to usable fuel precursors are approaches to overcoming this challenge. The two-electron reduction of carbon dioxide to carbon monoxide is an appealing process because CO can be used as a commodity chemical in industrial processes. Many molecular CO2 reduction catalysts have been reported and commonly use expensive late transition metals. These systems are inspired by natural photosynthesis and generally combine a photosensitizer, a catalyst, and a sacrificial electron donor. This work focuses nickel and gold complexes as …
The Development Of Novel Rhenium- And Copper-Based Molecular Catalysts For Applications In Energy Conversion Chemistry, Joseph Michael Lee
The Development Of Novel Rhenium- And Copper-Based Molecular Catalysts For Applications In Energy Conversion Chemistry, Joseph Michael Lee
Electronic Theses and Dissertations
Since the Industrial Revolution, the consumption of fossil fuels has increased dramatically worldwide. The combustion of fossil fuels leads to the generation of carbon dioxide (CO2) emissions. CO2 is a greenhouse gas, but also a C1 feedstock that could be utilized for the generation of renewable fuels and commodity chemicals. However, CO2 is chemically inert and typically demands strong chemical reductants or very negative potentials before it undergoes conversion into reduced carbon products. The desire to carry out CO2 conversion in the presence of water presents a significant challenge, as protons may be reduced to hydrogen gas rather than facilitating …
Development Of Cobalt And Iron Catalysts Bearing Rigid Polydentate Ligands For Proton Reduction And C-H Bond Oxidation, Lizhu Chen
Electronic Theses and Dissertations
The demand for energy consumption has increased exponentially since the Industrial Revolution. The major source of this energy has been and continues to be fossil fuels. The depletion of fossil fuels and environmental concerns associated with their combustion has motivated us to develop a renewable energy alternative to meet future energy demands. Hydrogen is a clean energy alternative to fossil fuels, which can be generated from solar-driven water splitting. However, more efficient and inexpensive catalysts for the hydrogen evolution reaction (HER) are needed. In this context, hydrogen production has been investigated with a stable and highly reactive cobalt-based catalyst. While …
X-Ray Crystal Structure Of Au36(Sph-Pch3)24 Nanomolecules, Vigneshraja Ganeshraj
X-Ray Crystal Structure Of Au36(Sph-Pch3)24 Nanomolecules, Vigneshraja Ganeshraj
Electronic Theses and Dissertations
Au36(SR)24 is one of the most comNanomolecules (NM) in gold NM field and crystal structures of Au36(SR)24 with different thiolate protecting ligand such as tert-butylbenzene thiol, thiophenol and cyclopentane thiol have been reported. It has been predicted that aromatic thiol protected Au36(SR)24 NM have same core structures like the other reported Au36(SR)24 NMs. Due to the steric and electronic conjugation effects the staples on the gold core exhibit minor changes in the bond length without affecting the gold core. By varying the Gold:Thiol ratio the NM size can be controlled. Herein, we report the synthesis, isolation and characterization of two …
Ligand Effect On Gold Nanomolecules Demonstrated Using Aliphatic, Aromatic And Bulky Thiolate Ligands, Milan Rambukwella
Ligand Effect On Gold Nanomolecules Demonstrated Using Aliphatic, Aromatic And Bulky Thiolate Ligands, Milan Rambukwella
Electronic Theses and Dissertations
Atomically precise thiolate protected gold nanoparticles (AuNPs) known as gold nanomolecules (AuNMs) are intensely pursued owing to their feasibility to elucidate their structure by single crystal X-ray crystallography. They have distinct number of Au atoms (n) and thiolate (-SR, R-hydrocarbon chain) ligands (m) with molecular formula of the form [Aun(SR)m]. AuNMs are made of a gold core protected by a thiolate-monolayer and possess size-dependent properties conferred by quantum confinement. Atomic precision has been achieved in the 1-3 nm range and crystal structures of several AuNMs ranging from 18 to 279gold atoms have been studied. They provide significant insights into the …