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2023

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Articles 421 - 450 of 1539

Full-Text Articles in Chemistry

Polymer Architecture Effect On Rheology And Segmental Dynamics In Poly (Methyl Methacrylate)-Silica Nanocomposite Melts, Saeid Darvishi, Erkan Şenses Aug 2023

Polymer Architecture Effect On Rheology And Segmental Dynamics In Poly (Methyl Methacrylate)-Silica Nanocomposite Melts, Saeid Darvishi, Erkan Şenses

Turkish Journal of Chemistry

Architecturally different polymer chains lead to fundamentally different rheological responses and internal dynamics, which can be utilized to rationalize advanced thermoplastic nanocomposites with tunable mechanical behavior. In this work, three model poly (methyl methacrylate) (PMMA) polymers with linear, bottlebrush, and star architectures with the same total molar mass were investigated in their neat form, and nanocomposites with well-dispersed silica nanoparticles using rheology and broadband dielectric spectroscopy (BDS). The master curves of the dynamic moduli obtained by time-temperature superposition (TTS) over the entire range from the Rouse regime to the terminal flow and a sequence of significantly different relaxation modes were …

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Electronic Structures And Dielectric Function Of (5, 5) Cnt-C2h4o System: A First-Principles Study On The Detection Capability Of Cnt For Gas Sensing Applications, Alvanh Alem Pido, Art Anthony Munio Aug 2023

Electronic Structures And Dielectric Function Of (5, 5) Cnt-C2h4o System: A First-Principles Study On The Detection Capability Of Cnt For Gas Sensing Applications, Alvanh Alem Pido, Art Anthony Munio

Turkish Journal of Chemistry

Carbon nanotubes (CNTs) are known to have a wide range of applications in various fields of discipline. In this research, the ability of metallic armchair (5, 5) CNT to detect acetaldehyde (C2 H4 O) was investigated using first-principles density functional theory (DFT) as implemented in Quantum ESPRESSO with the Generalized Gradient Approximation (GGA). Accordingly, it was found that C2 H4 O preserved the metallic behavior of the CNT. However, some bands are found to have overlapped in both the valence and conduction regions of the electronic structures of the resulting system that are mainly caused by the p orbitals of …

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Hydrodynamic Voltammetry Of Fe2+/3+ In Aqueous Deep Eutectic Solvents Towards Redox Flow Batteries, Desiree Mae Prado, Xiaochen Shen, Robert Savinell, Clemens Burda Aug 2023

Hydrodynamic Voltammetry Of Fe2+/3+ In Aqueous Deep Eutectic Solvents Towards Redox Flow Batteries, Desiree Mae Prado, Xiaochen Shen, Robert Savinell, Clemens Burda

Faculty Scholarship

Deep eutectic solvents (DESs) have recently attracted much attention as potential green electrolyte solvents for redox flow batteries. DESs are considered not only as environmentally sustainable but also economically attractive electrolytes because they can be resourced from biological feedstock (alcohols, urea, choline) and are earth-abundant and of low toxicity. Despite these advantages, DESs still have limitations in important aspects such as reactant and ion transport, which is inhibited due to hydrogen-bonding-induced viscosity. Thus, improving the transport properties of redox species in DESs is essential. In addition, we explore the quantitative addition of water to ethaline (a 1:2 choline chloride: ethylene …

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Anharmonicity And Deuteration In The Ir Absorption And Emission Spectra Of Phenylacetylene, Vincent J. Esposito, Pierro Ferrari, Wybren Jan Buma, Christiaan Boersma, Cameron J. Mackie, Alessandra Candian, Ryan C. Fortenberry, Alexander G. G. M. Tielens Aug 2023

Anharmonicity And Deuteration In The Ir Absorption And Emission Spectra Of Phenylacetylene, Vincent J. Esposito, Pierro Ferrari, Wybren Jan Buma, Christiaan Boersma, Cameron J. Mackie, Alessandra Candian, Ryan C. Fortenberry, Alexander G. G. M. Tielens

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Anharmonic cascade emission simulations, herein evinced by full reproduction and deep insights into recent emission spectroscopy experiments of phenylacetylene, are integral to the future successful analysis of JWST observational spectra. Experimental infrared absorption experiments conducted in this study reveal a complex spectrum dominated by quantum effects that are uncovered by anharmonic computational analysis. From this work, it becomes clear that phenylacetylene exhibits strong resonance coupling between fundamental and two-quanta combination modes as well as giving indication for coupling with higher-order, three-quanta combination bands. This study benchmarks the development of advanced computational methods that will be extended to larger systems of …

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Online Data Transmission Reduction Scheme For Energy Conservation In Wireless Video Sensor Networks, Iman Kadhum Abbood, Ali Kadhum Idrees Aug 2023

Online Data Transmission Reduction Scheme For Energy Conservation In Wireless Video Sensor Networks, Iman Kadhum Abbood, Ali Kadhum Idrees

Karbala International Journal of Modern Science

Wireless Video Sensor Networks (WVSNs) are networks of low-cost, low-power camera sensor nodes. These nodes communicate locally and process information to meet an application's goal. WVSNs are extensively used in diverse monitoring applications, such as security, military, industrial, medical, and environmental monitoring. However, the transmission of large amounts of data collected by video sensor nodes in WVSNs poses challenges in terms of energy consumption, bandwidth usage, and network congestion. Reducing energy for processing and transmitting data in WVSNs is difficult due to the huge amount of sensed data in real-time. To address this issue, this paper proposes an Online Data …

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Biogenesis Synthesis Of Zno Nps: Its Adsorption And Photocatalytic Activity For Removal Of Acid Black 210 Dye, Zahraa A. Najm, Mohammed A. Atiya, Ahmed K. Hassan Aug 2023

Biogenesis Synthesis Of Zno Nps: Its Adsorption And Photocatalytic Activity For Removal Of Acid Black 210 Dye, Zahraa A. Najm, Mohammed A. Atiya, Ahmed K. Hassan

Karbala International Journal of Modern Science

This study investigated the treatment of textile wastewater contaminated with Acid Black 210 dye (AB210) using zinc oxide nanoparticles (ZnO NPs) through adsorption and photocatalytic techniques. ZnO NPs were synthesized using a green synthesis process involving eucalyptus leaves as reducing and capping agents. The synthesized ZnO NPs were characterized using UV-Vis spectroscopy, SEM, EDAX, XRD, BET, Zeta potential, and FTIR techniques. The BET analysis revealed a specific surface area and total pore volume of 26.318 m2/g. SEM images confirmed the crystalline and spherical nature of the particles, with a particle size of 73.4 nm. A photoreactor was designed …

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Optimization Of Electrode Configurations For Calibration-Free, Remote Sensing Of Heavy Metals In Water Using Double-Potenital Step Anodic Coulometry, Jessica Bone Aug 2023

Optimization Of Electrode Configurations For Calibration-Free, Remote Sensing Of Heavy Metals In Water Using Double-Potenital Step Anodic Coulometry, Jessica Bone

Online Theses and Dissertations

Many areas around the world are known and predicted to suffer from arsenic-contaminated drinking water resulting in elevated medical issues. Current arsenic detection techniques require that a sample be taken at the site, carried to the lab, and then tested by a skilled technician, which is not practical for remote, hard to reach places. In collaboration with researchers at the University of Louisville and the University of Kentucky, we are designing an electrochemical cell for a calibration-free detection technique that can be performed remotely, eliminating the need for on-site technicians, and helping to prevent chronic arsenic poisoning. A validated and …

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Introducing High School Biology Students To Biochemistry With A Short, Content-Oriented Module, Archer Harrold, Allison Cruikshank, Bryan Penas, Rebecca Roston Aug 2023

Introducing High School Biology Students To Biochemistry With A Short, Content-Oriented Module, Archer Harrold, Allison Cruikshank, Bryan Penas, Rebecca Roston

Department of Chemistry: Faculty Publications

Many STEM disciplines are underrepresented to High School students. This is problematic as many students' decisions for college are shaped by their experiences and achievements in high school. Short content-oriented modules have been shown to encourage science identity and otherwise benefit the students' learning. Following the ASBMB's outreach protocol, we developed a short content-oriented module aimed at a high school biology classroom. Students interacted with 3D models of DNA and transcription factors while exploring structure–function relationships and introductory biochemistry topics. The high school teacher was impressed with the students' response to the module, specifically the ease with which students learned, …

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Ultrasound Assisted Comparative Study Of Fucolam And So-Dium Alginate And Impact On Their Physiochemical Proper-Ties Using Box-Behnken Design, Uday Bagale, Ammar Kadi, Artem Malinin, Varisha Anjum, Irina Potoroko Aug 2023

Ultrasound Assisted Comparative Study Of Fucolam And So-Dium Alginate And Impact On Their Physiochemical Proper-Ties Using Box-Behnken Design, Uday Bagale, Ammar Kadi, Artem Malinin, Varisha Anjum, Irina Potoroko

Karbala International Journal of Modern Science

The article discusses about the possibility of comparing the impact of ultrasonic treatment on fucolam and sodium algi-nate. The purpose was to study the effect of micronization on the sulfated heteropolysaccharide fucolam, analyzing its dispersed state and accessibility by reducing its molecular weight and increasing antioxidant activity. The optimization of the micronization process was carried out using the Box-Behnken Design (BBD) method, with a sonication time ranging from 15 to 45 min, power ranging from 50 to 100 W/cm2, and temperature between 30 °C and 40 °C. The fixed lower fucolam concentration was 0.1%. The results illustrated that sonochemical treatment …

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Deep Learning-Based Cad System For Predicting The Covid-19 X-Ray Images, Aqeel R. Talib, Hana’ M. Ali Aug 2023

Deep Learning-Based Cad System For Predicting The Covid-19 X-Ray Images, Aqeel R. Talib, Hana’ M. Ali

Karbala International Journal of Modern Science

According to World Health Organization data, Coronavirus (COVID-19) has infected about 660, 378, 145 patients around the world. It is nonetheless difficult for physicians to detect COVID-19 infections out of CT or X-ray radiographs. Thus, several computer-aided diagnosis (CAD) systems based on deep learning and radiographs were developed to detect COVID-19 infections. However, the majority of approaches considered small datasets, which is ineligible to provide diverse COVID-19 radiographs. This work utilizes a massive number of X-ray radiographs, and compared standard CNN, DenseNet-121, and GoogLeNet for isolating COVID-19 infections out from normal and other pneumonia radiographs. The dataset in this work …

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Additive Effects Of Cyclic Peptide [R4w4] When Added Alongside Azithromycin And Rifampicin Against Mycobacterium Avium Infection, Melissa Kelley, Kayvan Sasaninia, Arbi Abnousian, Ali Badaoui, James Owens, Abrianna Beever, Nala Kachour, Rakesh Kumar Tiwari, Vishwanath Venketaraman Aug 2023

Additive Effects Of Cyclic Peptide [R4w4] When Added Alongside Azithromycin And Rifampicin Against Mycobacterium Avium Infection, Melissa Kelley, Kayvan Sasaninia, Arbi Abnousian, Ali Badaoui, James Owens, Abrianna Beever, Nala Kachour, Rakesh Kumar Tiwari, Vishwanath Venketaraman

Pharmacy Faculty Articles and Research

Mycobacterium avium (M. avium), a type of nontuberculous mycobacteria (NTM), poses a risk for pulmonary infections and disseminated infections in immunocompromised individuals. Conventional treatment consists of a 12-month regimen of the first-line antibiotics rifampicin and azithromycin. However, the treatment duration and low antibiotic tolerability present challenges in the treatment of M. avium infection. Furthermore, the emergence of multidrug-resistant mycobacterium strains prompts a need for novel treatments against M. avium infection. This study aims to test the efficacy of a novel antimicrobial peptide, cyclic [R4W4], alongside the first-line antibiotics azithromycin and rifampicin in reducing M. avium survival. Colony-forming unit (CFU) …

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The Synthesis And Optimization Of Conductive Carbons From Renewable Resources For Supercapacitor Applications, Iris Denmark Aug 2023

The Synthesis And Optimization Of Conductive Carbons From Renewable Resources For Supercapacitor Applications, Iris Denmark

Theses and Dissertations

The use of fossil fuels has played a pivotal role in the evolution of energy storage devices and the generation of electricity. With that, we have now entered an era in which we have become primarily dependent on these non-renewable resources which have become increasingly scarce overtime. This has driven us toward a pertinent demand for alternative sources of energy. There are various forms of alternative energy in which biomass is the most used. Carbon is becoming the most commonly used material for energy applications due to its versatility and bioavailability, including that which is sourced from biomass. Herein is …

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Ruthenium Olefin Metathesis Catalysts Featuring Chelating Benzylidene-Triazole Ligands, Allegra L. Liberman-Martin Aug 2023

Ruthenium Olefin Metathesis Catalysts Featuring Chelating Benzylidene-Triazole Ligands, Allegra L. Liberman-Martin

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

In this issue of Chem Catalysis, Shi and co-workers describe the synthesis and olefin metathesis activity of ruthenium complexes with chelating benzylidene-triazole ligands. Catalyst decomposition is slow at up to 80°C, which enables challenging catalytic reactions, including cross-metathesis of trans-alkenes and macrocycle synthesis by dynamic covalent chemistry.

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Mechanochemical Esterification Of Cellulose Nanofibers Lyophilized From Eutectic Water–Tert-Butanol Mixtures, Miran Mavlan, Taehoo Chang, Rudan Feng, Jake R. Wilkinson, Robert J. Nicholas, Nosa B. Idahagbon, Jeffrey Youngblood, Alexander Wei Aug 2023

Mechanochemical Esterification Of Cellulose Nanofibers Lyophilized From Eutectic Water–Tert-Butanol Mixtures, Miran Mavlan, Taehoo Chang, Rudan Feng, Jake R. Wilkinson, Robert J. Nicholas, Nosa B. Idahagbon, Jeffrey Youngblood, Alexander Wei

Department of Chemistry Faculty Publications

Freeze-dried CNFs can be modified by mechanochemical (MC) processes with minimal use of auxiliary solvents, however aggregation of nanofibers during lyophilization compromises their granularity and reaction efficiency. Adding 10 wt% tert-butanol (TBA) to aqueous slurries of wood-derived CNF creates a eutectic mixture that reduces hornification during lyophilization, resulting in well-formed aerogels with minimal shrinkage in volume. CNFs lyophilized from mixtures containing at least 10 wt% TBA exhibit an order of magnitude increase in specific surface area relative to CNFs freeze-dried from water alone. The amount of TBA and input energy needed for lyophilization can be reduced considerably by dewatering …

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Changes In An Enzyme Ensemble During Catalysis Observed By High Resolution Xfel Crystallography, Nathan J. Smith, Medhanjali Dasgupta, David C. Wych, Cole Dolamore, Raymond G. Sierra, Stella Lisova, Darya Marchany-Rivera, Aina E. Cohen, Sébastien Boutet, Mark S. Hunter, Christopher Kupitz, Frédéric Poitevin, Frank R. Moss Iii, Aaron S. Brewster, Nicholas K. Sauter, Iris D. Young, Alexander M. Wolff, Virendra K. Tiwari, Nivesh Kumar, David B. Berkowitz, Ryan G. Hadt, Michael C. Thompson, Alec H. Follmer, Mark A. Wilson Aug 2023

Changes In An Enzyme Ensemble During Catalysis Observed By High Resolution Xfel Crystallography, Nathan J. Smith, Medhanjali Dasgupta, David C. Wych, Cole Dolamore, Raymond G. Sierra, Stella Lisova, Darya Marchany-Rivera, Aina E. Cohen, Sébastien Boutet, Mark S. Hunter, Christopher Kupitz, Frédéric Poitevin, Frank R. Moss Iii, Aaron S. Brewster, Nicholas K. Sauter, Iris D. Young, Alexander M. Wolff, Virendra K. Tiwari, Nivesh Kumar, David B. Berkowitz, Ryan G. Hadt, Michael C. Thompson, Alec H. Follmer, Mark A. Wilson

Department of Chemistry: Faculty Publications

Enzymes populate ensembles of structures with intrinsically different catalytic proficiencies that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL) to observe catalysis in a designed mutant (G150T) isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations and formation of the thioimidate catalytic intermediate selects for catalytically competent substates. A prior proposal for active site cysteine charge-coupled conformational changes in ICH is validated by determining structures of the enzyme over a range of pH values. A combination of large …

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Change Is The Only Constant: A Virtual Issue On Contemporary Catalysis, Shelley Minteer, Stephanie L. Brock, Géraldine Masson, Raymond E. Schaak Aug 2023

Change Is The Only Constant: A Virtual Issue On Contemporary Catalysis, Shelley Minteer, Stephanie L. Brock, Géraldine Masson, Raymond E. Schaak

Chemistry Faculty Research & Creative Works

No abstract provided.

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Unraveling Hydrogen Atom Transfer Mechanisms With Voltammetry: Oxidative Formation And Reactivity Of Cobalt Hydride, Dylan G. Boucher, Andrew D. Pendergast, Xiangyu Wu, Zachary A. Nguyen, Rohit G. Jadhav, Song Lin, Henry S. White, Shelley D. Minteer Aug 2023

Unraveling Hydrogen Atom Transfer Mechanisms With Voltammetry: Oxidative Formation And Reactivity Of Cobalt Hydride, Dylan G. Boucher, Andrew D. Pendergast, Xiangyu Wu, Zachary A. Nguyen, Rohit G. Jadhav, Song Lin, Henry S. White, Shelley D. Minteer

Chemistry Faculty Research & Creative Works

The utility of transition metal hydride catalyzed hydrogen atom transfer (MHAT) has been widely demonstrated in organic transformations such as alkene isomerization and hydro functionalization reactions. However, the highly reactive nature of the hydride and radical intermediates has hindered mechanistic insight into this pivotal reaction. Recent advances in electrochemical MHAT have opened up the possibility for new analytical approaches for mechanistic diagnosis. Here, we report a voltametric interrogation of Co-Based MHAT reactivity, describing in detail the oxidative formation and reactivity of the key Co-H intermediate and its reaction with aryl alkenes. Insights from cyclic voltammetry and finite element simulations help …

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Rural Science Teachers Social Network Analysis Matrices, Rebecca L. Sansom, Tracy Poulsen Aug 2023

Rural Science Teachers Social Network Analysis Matrices, Rebecca L. Sansom, Tracy Poulsen

ScholarsArchive Data

These are the social network matrices for our study of rural science teachers. Each matrix is located on a separate tab on the spreadsheet.

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Synthesis And Characterization Of The N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase (Dape) Alternate Substrate Analog N,N-Dimethyl-L,L-Sdap, Zachary J. Liveris, Emma H. Kelley, Emma Simmons, Katherine Konczak, Marlon Lutz Jr., Miguel Ballicora, Ken W. Olsen, Daniel P. Becker Ph.D. Aug 2023

Synthesis And Characterization Of The N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase (Dape) Alternate Substrate Analog N,N-Dimethyl-L,L-Sdap, Zachary J. Liveris, Emma H. Kelley, Emma Simmons, Katherine Konczak, Marlon Lutz Jr., Miguel Ballicora, Ken W. Olsen, Daniel P. Becker Ph.D.

Chemistry: Faculty Publications and Other Works

Growing antibiotic resistance by pathogenic bacteria has led to a global crisis. The bacterial enzyme N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) provides a very attractive target for the discovery of a new class of antibiotics, as it resides exclusively in many pathogenic bacterial strains and is a key enzyme in the lysine biosynthetic pathway. This pathway is responsible for the production of lysine as well as meso-diaminopimelate (m-DAP), both of which are required for peptidoglycan cell-wall synthesis, and lysine for peptide synthesis. The enzyme DapE catalyzes the hydrolysis of N-succinyl-l,l-diaminopimelic acid (l,l-SDAP) to succinate and l,l-diaminopimelic …

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Self-Immolative Hydrogels With Stimulus-Mediated On-Off Degradation., Jue Gong, Aneta Borecki, Elizabeth R Gillies Aug 2023

Self-Immolative Hydrogels With Stimulus-Mediated On-Off Degradation., Jue Gong, Aneta Borecki, Elizabeth R Gillies

Chemistry Publications

Hydrogels are of interest for a wide range of applications from sensors to drug delivery and tissue engineering. Self-immolative polymers, which depolymerize from end-to-end following a single backbone or end-cap cleavage, offer advantages such as amplification of the stimulus-mediated cleavage event through a cascade degradation process. It is also possible to change the active stimulus by changing only a single end-cap or linker unit. However, there are very few examples of self-immolative polymer hydrogels, and the reported examples exhibited relatively poor stability in their nontriggered state or slow degradation after triggering. Described here is the preparation of hydrogels composed of …

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Enhancing The Performance Of Microbial Fuel Cells Via Metabolic Engineering Of Escherichia Coli For Phenazine Production, Olja Simoska, Dale A. Cummings, Erin M. Gaffney, Claire Langue, Tommy G. Primo, Courtney J. Weber, Corbin E. Witt, Shelley D. Minteer Aug 2023

Enhancing The Performance Of Microbial Fuel Cells Via Metabolic Engineering Of Escherichia Coli For Phenazine Production, Olja Simoska, Dale A. Cummings, Erin M. Gaffney, Claire Langue, Tommy G. Primo, Courtney J. Weber, Corbin E. Witt, Shelley D. Minteer

Chemistry Faculty Research & Creative Works

One of the central roles in the design, development, and application advances in mediator-Based microbial electrochemical systems, such as microbial fuel cells (MFCs), is the establishment of efficient and successful communication between conductive electrode surfaces and microorganisms via modes of extracellular electron transfer (EET). Most microbial-Based systems require the use of artificial electroactive mediators in order to facilitate and/or enhance electron transfer. Our previous work established an exogenous phenazine-Based library as a mediator system to enable EET from the model microorganism Escherichia coli as a promising biotechnological host. However, the addition of exogenous mediators to a microbial electrochemical system has …

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On The Boundary Of The Cosmos, Daniel Linford Aug 2023

On The Boundary Of The Cosmos, Daniel Linford

Department of Chemistry: Faculty Publications

Intuitively, the totality of physical reality – the Cosmos – has a beginning only if (i) all parts of the Cosmos agree on the direction of time (the Direction Condition) and (ii) there is a boundary to the past of all non-initial spacetime points such that there are no spacetime points to the past of the boundary (the Boundary Condition). Following a distinction previously introduced by J. Brian Pitts, the Boundary Condition can be conceived of in two distinct ways: either topologically, i.e., in terms of a closed boundary, or metrically, i.e., in terms of the Cosmos having a finite …

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Crystal Environment Induced Symmetry Reduction (Ceisr): Deep Analysis Of Para-Chloroacetophenone Azine And Generalization, Harmeet Bhoday, Kaidi Yang, Steven P. Kelley, Rainer Glaser Aug 2023

Crystal Environment Induced Symmetry Reduction (Ceisr): Deep Analysis Of Para-Chloroacetophenone Azine And Generalization, Harmeet Bhoday, Kaidi Yang, Steven P. Kelley, Rainer Glaser

Chemistry Faculty Research & Creative Works

The morphologies of sixteen crystal structures of ten symmetrical Xpara-Ph-(Me)C 00000000 00000000 00000000 00000000 11111111 = N-N = C (Me)-Ph-Xpara azines: 1 (Cl), 2 (Br), 3 (I), 4 (OH), 5 (PhO), 6 (CF3), 7 (F), 8 (Me), 9 (NO2), and 10 (PrO) are described. All the azines crystallize forming idioteloamphiphile monolayers (IAMs) and their morphologies fall into the two main classes of "flat" and "shiplap" depending on the lateral offsets between next neighbors in the monolayer. Ab initio studies show that the (E,E)-configured p-disubstituted acetophenone azines are C2-symmetric in the gas phase and that the azine and phenyl twists are …

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Transition Metal-Catalyzed Functionalization Of Carbon-Hydrogen Bonds In Alkenes, Xiaolin Qian Aug 2023

Transition Metal-Catalyzed Functionalization Of Carbon-Hydrogen Bonds In Alkenes, Xiaolin Qian

Theses and Dissertations

Alkenes can undergo a variety of chemical reactions to form more complex molecules with a range of functional groups. This makes them useful starting materials for synthesizing a wide range of organic compounds. Chapter I provided an overview of the development history of alkenyl C−H bond activation. The early reactions of C−H compounds with metal complexes, as well as stoichiometric activation of the transition metal-activated C–H bond, were discussed. Then the first successful and efficient organometallic-catalyzed transformations of a C−H bond, the first transition metal-catalyzed vinylic C–H functionalization, and the first transition metal-catalyzed olefinic C–H functionalization under mild conditions were …

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A Critical Inter-Subunit Interaction For The Transmission Of The Allosteric Signal In The Agrobacterium Tumefaciens Adp-Glucose Pyrophosphorylase, Hiral Patel, Gabriela Martinez-Ramirez Ms., Emily Dobrzynski, Alberto A. Iglesias, Dali Liu, Miguel Ballicora Aug 2023

A Critical Inter-Subunit Interaction For The Transmission Of The Allosteric Signal In The Agrobacterium Tumefaciens Adp-Glucose Pyrophosphorylase, Hiral Patel, Gabriela Martinez-Ramirez Ms., Emily Dobrzynski, Alberto A. Iglesias, Dali Liu, Miguel Ballicora

Chemistry: Faculty Publications and Other Works

ADP-glucose pyrophosphorylase is a key regulatory enzyme involved in starch and glycogen synthesis in plants and bacteria, respectively. It has been hypothesized that inter-subunit communications are important for the allosteric effect in this enzyme. However, no specific interactions have been identified as part of the regulatory signal. The enzyme from Agrobacterium tumefaciens is a homotetramer allosterically regulated by fructose 6-phosphate and pyruvate. Three pairs of distinct subunit-subunit interfaces are present. Here we focus on an interface that features two symmetrical interactions between Arg11 and Asp141 from one subunit with residues Asp141 and Arg11 of the neighbor subunit, respectively. Previously, scanning …

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Fabrication And Imaging Of Highly Ordered Plasmonic Au Nano-Prism And Self-Assembled Supramolecular Nanostructure, Ridwan Tobi Ayinla Aug 2023

Fabrication And Imaging Of Highly Ordered Plasmonic Au Nano-Prism And Self-Assembled Supramolecular Nanostructure, Ridwan Tobi Ayinla

Theses and Dissertations

The precise control of the resonance frequency of plasmonic nanostructures is critical and depends on the size, composition, shape, and dielectric nature of the environment. The ability to control the shape and size of nanomaterials acutely depends on the fabrication technique and material design. We used a cheap and scalable method known as nanosphere lithography (NSL) to fabricate plasmonic nano-prism (NP) on glass and indium tin oxide substrate (ITO). The methods involve substrate hydrophilicity treatment, polystyrene nanosphere masking, metal deposition, and mask removal. The array and specific morphology of the fabricated NP was established using scanning electron microscope (SEM) and …

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Improved Stoichiometric Synthesis Of Ccc-Nhc Pincer Rh Complexes And Catalytic Activity Towards Dehydrogenative Silylation And Hydrosilylation Of Alkenes, Enock Amoateng Aug 2023

Improved Stoichiometric Synthesis Of Ccc-Nhc Pincer Rh Complexes And Catalytic Activity Towards Dehydrogenative Silylation And Hydrosilylation Of Alkenes, Enock Amoateng

Theses and Dissertations

N-Heterocyclic carbenes (NHCs) have attracted growing interest not only as successful ancillary ligands in a wide variety of transition-metal-catalyzed reactions but have also shown to offer photophysical and electrochemical properties. The metalation/transmetalation strategy using [Zr(NMe2)4] as initial metalating reagent offers an efficient approach to the preparation of CCC-NHC pincer complexes of the late transition metals such as Rh and Ir. In the process of investigating an intermediate and the mechanism of the metalation/transmetalation to Rh sequence, a mixed valent bimetallic CCC-NHC pincer Rh complex with two chloro ligands bridged between a [(CCC-NHC)Rh(III)] and a [Rh(I)(COD)] fragment …

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Synthesis And Characterization Of Redox-Noninnocent Pyrazine(Diimine) Iron Complexes And An Inverted Pyridine(Diimine) Ligand, Jaylan Billups Aug 2023

Synthesis And Characterization Of Redox-Noninnocent Pyrazine(Diimine) Iron Complexes And An Inverted Pyridine(Diimine) Ligand, Jaylan Billups

Theses and Dissertations

Cooperativity between the metal center and the ligand has been shown in nature to be an important feature of systems that catalyze two-electron processes that first-row transition metals usually cannot catalyze on their own. In these cases, the ligand acts as a site of reactivity that in many instances can store electrons or react directly with substrates in solution. The design and study of systems where there is synergy between the metal and the ligand have been leveraged to catalyze polymerization and hydrogenation-type reactions as well as the activation of small molecules such as dihydrogen. Specifically, the pyridine(diimine) ligand scaffold …

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Identifying Student Challenges In Organic Chemistry: Supporting Student Understanding Through Eye-Tracking, Think-Aloud Interviews And Alternative Questions, Lisa Ann Smith Aug 2023

Identifying Student Challenges In Organic Chemistry: Supporting Student Understanding Through Eye-Tracking, Think-Aloud Interviews And Alternative Questions, Lisa Ann Smith

Theses and Dissertations

Think-aloud interviews are a strategy used to identify misconceptions held by students. We incorporated think-aloud interviews and studied representational competence of novice and expert participants with identifying alkyl halides with multiple representations. We hypothesized that the participants would approach representations differently and think-aloud interviews would reveal misconceptions. Eye-tracking results showed that novice and expert participants differ in their approaches to representations and that novice participants spend more time on representations. Think-aloud interviews revealed that novice participants contain misconceptions on alkyl halide identification. This research provided insights on student understanding in identifying alkyl halides and representations, allowing instructors to use student …

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Uncoupling System And Environment Simulation Cells For Fast-Scaling Modeling Of Complex Continuum Embeddings, G. Medrano, E. Bainglass, O. Andreussi Aug 2023

Uncoupling System And Environment Simulation Cells For Fast-Scaling Modeling Of Complex Continuum Embeddings, G. Medrano, E. Bainglass, O. Andreussi

Chemistry and Biochemistry Faculty Publications and Presentations

Continuum solvation models are becoming increasingly relevant in condensed matter simulations, allowing to characterize materials interfaces in the presence of wet electrified environments at a reduced computational cost with respect to all atomistic simulations. However, some challenges with the implementation of these models in plane-wave simulation packages still persists, especially when the goal is to simulate complex and heterogeneous environments. Among these challenges is the computational cost associated with large heterogeneous environments, which in plane-wave simulations has a direct effect on the basis-set size and, as a result, on the cost of the electronic structure calculation. Moreover, the use of …

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