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Articles 2881 - 2910 of 33142

Full-Text Articles in Chemistry

Multiple Imputation For Robust Cluster Analysis To Address Missingness In Medical Data, Arnold Harder, Gayla R. Olbricht, Godwin Ekuma, Daniel B. Hier, Tayo Obafemi-Ajayi Jan 2024

Multiple Imputation For Robust Cluster Analysis To Address Missingness In Medical Data, Arnold Harder, Gayla R. Olbricht, Godwin Ekuma, Daniel B. Hier, Tayo Obafemi-Ajayi

Mathematics and Statistics Faculty Research & Creative Works

Cluster Analysis Has Been Applied To A Wide Range Of Problems As An Exploratory Tool To Enhance Knowledge Discovery. Clustering Aids Disease Subtyping, I.e. Identifying Homogeneous Patient Subgroups, In Medical Data. Missing Data Is A Common Problem In Medical Research And Could Bias Clustering Results If Not Properly Handled. Yet, Multiple Imputation Has Been Under-Utilized To Address Missingness, When Clustering Medical Data. Its Limited Integration In Clustering Of Medical Data, Despite The Known Advantages And Benefits Of Multiple Imputation, Could Be Attributed To Many Factors. This Includes Methodological Complexity, Difficulties In Pooling Results To Obtain A Consensus Clustering, Uncertainty Regarding …

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A Spectrophotometric Determination Of Strontium Complexation With Methylthymol Blue, Adebayo Comlan Djanman Jan 2024

A Spectrophotometric Determination Of Strontium Complexation With Methylthymol Blue, Adebayo Comlan Djanman

Browse all Theses and Dissertations

This study examines the complexation behavior of methylthymol blue (MTB) with strontium, particularly focusing on its application in addressing environmental concerns related to radiotoxic 90Sr. Using spectrophotometric techniques, the binding interactions were analyzed at pH = 7.50, 9.60, and 12.20. Results indicate that MTB forms a 1:1 complex with strontium at pH = 7.50, while at pH = 9.60 and 12.20 were assumed to influence complexation due to changes in ligand deprotonation and electrostatic interactions. Equilibrium constants (K1) = 22 (± 2) and molar absorptivities, ε1 = 6.3 x 10^3 (± 0.0008) L·mol⁻¹·cm⁻¹, and ε2 = 9.73 x (± 0.2)10^3 …

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Corrosion Inhibitors: Mitigating The Degradation Of Rebar, Jake R. Hughes Jan 2024

Corrosion Inhibitors: Mitigating The Degradation Of Rebar, Jake R. Hughes

Williams Honors College, Honors Research Projects

Our conjecture was twofold: first, that two compounds historically used as food preservatives could act as environmentally friendly inhibitors against rebar corrosion, and second, that molecular properties have a quantifiable influence on inhibition efficiency (%IE). To evaluate the two compounds, cyclic potentiodynamic polarization was used to determine corrosion current density (icorr) and %IE. The “green” inhibitor candidates included sodium metabisulfite and ascorbic acid, which yielded maximum %IE values of -123900% and 91%, respectively. Results indicated that sodium metabisulfite is not a suitable inhibitor, while ascorbic acid showed potential to extend reinforced concrete’s design life without posing health or …

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Assessing Fixed-Node Diffusion Monte Carlo For Radical Polymerization Reaction Energetics, Timothy Brian Huber Jan 2024

Assessing Fixed-Node Diffusion Monte Carlo For Radical Polymerization Reaction Energetics, Timothy Brian Huber

Graduate Research Theses & Dissertations

The art of quantum chemistry is grounded to the discovery of a time efficient computational method that can capture the essential physics. Historically, the Hartree-Fock method, where an electron moves in the mean field of the other electrons, has provided the orbitals used to construct a single-reference Slater determinant and thus formed the basis for molecular orbital calculations. Kohn-Sham density functionals have become overwhelmingly popular among the chemistry community due to their low computational cost. However, their prediction of thermodynamic properties important in free radical polymerization has shown difficulty due to an artificial delocalization of electron density and spin contamination …

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Excited State Proton Transfer From Acidic Alcohols To A Quinoline Photobase Can Be Solvated By Non-Acidic Alcohol Solvents, Jonathan Ryan Hunt, Joseph Hecht, Clara Goolsby, Jade Hagihara, Monique Loza, Samantha Del Pozo Jan 2024

Excited State Proton Transfer From Acidic Alcohols To A Quinoline Photobase Can Be Solvated By Non-Acidic Alcohol Solvents, Jonathan Ryan Hunt, Joseph Hecht, Clara Goolsby, Jade Hagihara, Monique Loza, Samantha Del Pozo

Chemistry and Biochemistry Faculty Works

Photobases are a type of molecule that become more basic upon photoexcitation and can therefore be used to control proton transfer reactions with light. The solvation requirements for excited state proton transfer (ESPT) in photobase systems is poorly understood, which limits their applicability. Here, we investigate the solvation of the ESPT reaction using 5-methoxyquinoline (MeOQ), a well-studied photobase with an excited state pKa (pKa*) of approximately 15.1, as a model system. Previous studies have shown that, in addition to the acidic donor that donates a proton to the photoexcited MeOQ, an additional “auxiliary donor” is necessary to solvate the resulting …

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Investigation Of Ion Pairing And Clustering Leading To The Nucleation Of Fluorite Using Ion Selective Electrode Potentiometry, Courtney L. Crone Jan 2024

Investigation Of Ion Pairing And Clustering Leading To The Nucleation Of Fluorite Using Ion Selective Electrode Potentiometry, Courtney L. Crone

Browse all Theses and Dissertations

Previously, mineral nucleation was described by Classical Nucleation Theory (CNT), a theory based on the thermodynamic properties of bulk materials. However, an alternative model, known as the Prenucleation Cluster Pathway, has been increasingly used to describe nucleation of minerals. This model considers the presence of thermodynamically stable ion clusters known as “prenucleation clusters” (PNCs). In the present research, the nucleation mechanism of calcium fluoride was investigated to identify evidence of PNCs by means of the ion-selective electrode (ISE) method, where a CaCl2 solution was titrated into a NaF solution while investigating the effects of saturation level and the aqueous ratio …

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The Role Of Sugars In Aggregation Of The Protein Kassinin, Lillie G. Waldron Jan 2024

The Role Of Sugars In Aggregation Of The Protein Kassinin, Lillie G. Waldron

Student Summer Scholars Manuscripts

The aggregation of proteins to form amyloids is implicated in several diseases such as Alzheimer’s Disease, Parkinson’s Disease, and many others. This aggregation has several stages, progressing from isolated protein molecules (monomers) to small aggregates (oligomers), which are toxic to cells, and finally to large, string-like mature aggregates. Despite this association with disease, functional amyloids, which have normal biological functions, also result from protein aggregation. Kassinin, an amphibian peptide involved in nerve signal transmission, is a model system for functional amyloid study. To compare the aggregation of functional and disease-causing amyloids, we previously synthesized a fluorine-labeled kassinin through solid-phase peptide …

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Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov Jan 2024

Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov

Theses and Dissertations

This study explores the potential of beryllium (Be) as an alternative dopant to magnesium (Mg) for achieving higher hole concentrations in gallium nitride (GaN). Despite Mg prominence as an acceptor in optoelectronic and high-power devices, its deep acceptor level at 0.22 eV above the valence band limits its effectiveness. By examining Be, this research aims to pave the way to overcoming these limitations and extend the findings to aluminum nitride and aluminum gallium nitride (AlGaN) alloy. Key contributions of this work include. i)Identification of three Be-related luminescence bands in GaN through photoluminescence spectroscopy, improving the understanding needed for further material …

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Effects Of Geometric Isomerism On Benzothiazole-Carbazole Based Tadf Emitters In Poly(Arylene Ether)S, Grace Olive Jan 2024

Effects Of Geometric Isomerism On Benzothiazole-Carbazole Based Tadf Emitters In Poly(Arylene Ether)S, Grace Olive

Browse all Theses and Dissertations

Thermally activated delayed fluorescence (TADF) small molecules have dominated the literature for their use in OLED devices. The use of TADF polymers has been employed to correct for processing issues that small molecules face, providing increased thermal stability and supportive electronic structures. A TADF chromophore based on a 2-(2,6-difluorophenyl)-benzothiazole-carbazole donor-acceptor pair was synthesized via a copper (I) catalyzed reaction. The chromophore exhibited peak absorption at 340 nm and emission at 477 nm. The resulting chromophore was incorporated into a poly(arylene ether) (PAE) backbone via nucleophilic aromatic substitution (NAS) with 4,4’-biphenol, 4,4’-difluorodiphenyl sulfone, and 2-(2,6-difluorophenyl)-benzothiazole as comonomers. UV/Vis analysis of the …

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A Physicochemical Characterization Of Protein Aggregates: Influence Of Lipid Membranes And Surfaces, Connor J. Hall Jan 2024

A Physicochemical Characterization Of Protein Aggregates: Influence Of Lipid Membranes And Surfaces, Connor J. Hall

Dissertations, Master's Theses and Master's Reports

Protein aggregation is a hallmark of neurodegenerative diseases (NDs). Although there has been a greater emphasis in the past decade or more on the correlation between the physicochemical characteristics of aggregates and their cellular toxicity, it is still unclear what specific features of an aggregate render it toxic. To better understand that, there has been a renewed focus on the characterization of unique biochemical and biophysical properties of protein aggregates. Elucidation of these unique characteristics can help to better understand disease pathogenesis in vivo. Furthermore, the lipid-rich nature of the brain sets it apart from all other organs, and numerous …

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Synthesis Of Long Oligodeoxynucleotides, Yipeng Yin Jan 2024

Synthesis Of Long Oligodeoxynucleotides, Yipeng Yin

Dissertations, Master's Theses and Master's Reports

Synthetic long oligodeoxynucleotides (ODNs) have found wide applications in diverse fields such as chemical biology, synthetic biology, and genes and genomes synthesis. Those applications leading to a significant demand for their production. However, traditional methods for purifying synthetic ODNs present notable drawbacks, particularly their inability to purify long ODNs, rendering long ODN synthesis challenging. To address these issues, chemical synthesis techniques for long ODNs coupled with non-chromatographic purification methods have been developed. This technology makes the purification of long synthetic ODNs feasible and offers a viable pathway for producing genes and genomes with extensive repeats or stable secondary structures, which …

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Tracking The Reaction Networks Of Criegee Intermediates Formed In The Ozone-Assisted Oxidation Reactions Of C5 Acyclic And Endocyclic Alkenes, Arden M. Floyd Jan 2024

Tracking The Reaction Networks Of Criegee Intermediates Formed In The Ozone-Assisted Oxidation Reactions Of C5 Acyclic And Endocyclic Alkenes, Arden M. Floyd

Honors Undergraduate Theses

Uni- and bi-molecular reactions involving Criegee intermediates (CIs), characteristic to alkene-ozone reactions, play an important role in synthetic organic, atmospheric, and combustion chemistry. However, difficulty in detecting key intermediates has prevented a thorough understanding of the details of the ozonolysis mechanism. To gain new insights into how alkene structure affects the CI network, the ozone assisted oxidation reactions of trans-2-pentene and cyclopentene are investigated between 320 K and 760 K in an atmospheric pressure jet stirred reactor (JSR). Molecular-beam mass spectrometry in conjunction with single photon tunable synchrotron VUV radiation is used to identify elusive intermediates by means of …

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Hybridization Kinetics Of Four-Way Junctions Localized On A Dna Scaffold, Katherine N. Taylor Jan 2024

Hybridization Kinetics Of Four-Way Junctions Localized On A Dna Scaffold, Katherine N. Taylor

Honors Undergraduate Theses

DNA computing is an ever-growing field with scientists trying to design structures that optimize logic gate communication to develop fast, biologically compatible, computational structures. We hypothesize that by using the principles of DNA computing, it is possible to design a DNA tile capable of studying localized DNA hybridization that can differentiate between oligonucleotides of different structural conformations. This includes synthetically manipulating DNA into a nanostructure that can perform Boolean logic functions to calculate the different rates of hybridization. To test our hypothesis, we designed a DNA Tile that incorporated a 4WJ using YES logic. Linear and hairpin single-stranded (ss) DNA …

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Detection Of Micrornas In Blood Samples Using Biosensors For The Detection Of Early-Stage Lung Cancer, Nicholas Bruno Jan 2024

Detection Of Micrornas In Blood Samples Using Biosensors For The Detection Of Early-Stage Lung Cancer, Nicholas Bruno

Honors Undergraduate Theses

Lung cancer kills more people in the U.S. a year than any other cancer. This is largely because patients often remain asymptomatic until stage 3, by which time the tumor is usually highly malignant. High radiation-producing screenings are the current method of lung tumor detection. These typically involve machinery for tumor visualization, such as computed tomography (CT) scans, positron emission tomography (PET scan), magnetic resonance imaging (MRI), and X-rays. Not only does radiation exposure from this equipment pose a risk to the patient, but any tumors detected by these scanning techniques are likely to be locally advanced. This suggests that …

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Mapping The Reaction Networks Of Cis Formed In The Ozone-Assisted Oxidation Of C₆ Acyclic And Endocyclic Alkenes, Zachary Clarke Jan 2024

Mapping The Reaction Networks Of Cis Formed In The Ozone-Assisted Oxidation Of C₆ Acyclic And Endocyclic Alkenes, Zachary Clarke

Honors Undergraduate Theses

Criegee intermediates (CIs) are highly reactive species generated during the ozonolysis of alkenes, exerting a critical influence on atmospheric oxidation, combustion chemistry, and synthetic processes. Their reactivity, encompassing unimolecular and bimolecular pathways, shapes oxidation mechanisms and product distributions in these environments. A key determinant of CI behavior is the structural nature of the parent alkene. Acyclic alkenes typically yield intermediates with minimal steric hindrance, facilitating rapid reactions, whereas endocyclic alkenes produce geometrically constrained CIs with enhanced internal stabilization, redirecting reaction pathways and reducing overall reactivity. Despite their importance, mechanistic understanding remains limited due to experimental challenges in detecting CIs and …

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Extended Conformations Of Bifurcating Electron Transfer Flavoprotein Constitute Up To Half The Population, Possibly Mediating Conformational Change, Sharique A. Khan, Alan Hicks, Wellington C. Leite, James Byrnes, Biswajit Gorai, Maria-Andrea Mroginski, Hugh O'Neill, Anne-Francis Miller Jan 2024

Extended Conformations Of Bifurcating Electron Transfer Flavoprotein Constitute Up To Half The Population, Possibly Mediating Conformational Change, Sharique A. Khan, Alan Hicks, Wellington C. Leite, James Byrnes, Biswajit Gorai, Maria-Andrea Mroginski, Hugh O'Neill, Anne-Francis Miller

Markey Cancer Center Faculty Publications

Electron transfer bifurcation enables biological systems to drive unfavourable (endergonic) electron transfer by coupling it to favourable (exergonic) transfer of a second electron. In electron transfer flavoproteins (ETFs), a domain-scale conformational change is believed to sever the favourable pathway after a single electron has used it, thereby preventing the energy dissipation that would accompany exergonic transfer of the second electron. To understand the conformation change that participates in turnover, we have deployed small-angle neutron scattering (SANS) and computational techniques to characterize the bifurcating ETF from Acidaminococcus fermentans (AfeETF). SANS data reveal an overall radius of gyration (Rg) of 30.1 ± …

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Biliverdin Reductase-A Integrates Insulin Signaling With Mitochondrial Metabolism Through Phosphorylation Of Gsk3Β, Chiara Lanzillotta, Antonella Tramutola, Simona Lanzillotta, Viviana Greco, Sara Pagnotta, Caterina Sanchini, Silvia Di Angelantonio, Elena Forte, Serena Rinaldo, Alessio Paone, Francesca Cutruzzolà, Flavia Agata Cimini, Ilaria Barchetta, Maria Gisella Cavallo, Andrea Urbani, D. Allan Butterfield, Fabio Di Domenico, Bindu D. Paul, Marzia Perluigi, Joao M.N. Duarte Jan 2024

Biliverdin Reductase-A Integrates Insulin Signaling With Mitochondrial Metabolism Through Phosphorylation Of Gsk3Β, Chiara Lanzillotta, Antonella Tramutola, Simona Lanzillotta, Viviana Greco, Sara Pagnotta, Caterina Sanchini, Silvia Di Angelantonio, Elena Forte, Serena Rinaldo, Alessio Paone, Francesca Cutruzzolà, Flavia Agata Cimini, Ilaria Barchetta, Maria Gisella Cavallo, Andrea Urbani, D. Allan Butterfield, Fabio Di Domenico, Bindu D. Paul, Marzia Perluigi, Joao M.N. Duarte

Markey Cancer Center Faculty Publications

Brain insulin resistance links the failure of energy metabolism with cognitive decline in both type 2 Diabetes Mellitus (T2D) and Alzheimer’s disease (AD), although the molecular changes preceding overt brain insulin resistance remain unexplored. Abnormal biliverdin reductase-A (BVR-A) levels were observed in both T2D and AD and were associated with insulin resistance. Here, we demonstrate that reduced BVR-A levels alter insulin signaling and mitochondrial bioenergetics in the brain. Loss of BVR-A leads to IRS1 hyper-activation but dys- regulates Akt-GSK3β complex in response to insulin, hindering the accumulation of pGSK3βS9 into the mito- chondria. This event impairs oxidative phosphorylation and fosters …

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Perfluorooctanesulfonic Acid Exposure Leads To Downregulation Of 3-Hydroxy-3-Methylglutaryl-Coa Synthase 2 Expression And Upregulation Of Markers Associated With Intestinal Carcinogenesis In Mouse Intestinal Tissues, Josiane Weber Tessmann, Pan Deng, Jerika Durham, Chang Li, Moumita Banerjee, Qingding Wang, Ryan A. Goettl, Daheng He, Chi Wang, Eun Y. Lee, B. Mark Evers, Bernhard Hennig, Yekaterina Y. Zaytseva Jan 2024

Perfluorooctanesulfonic Acid Exposure Leads To Downregulation Of 3-Hydroxy-3-Methylglutaryl-Coa Synthase 2 Expression And Upregulation Of Markers Associated With Intestinal Carcinogenesis In Mouse Intestinal Tissues, Josiane Weber Tessmann, Pan Deng, Jerika Durham, Chang Li, Moumita Banerjee, Qingding Wang, Ryan A. Goettl, Daheng He, Chi Wang, Eun Y. Lee, B. Mark Evers, Bernhard Hennig, Yekaterina Y. Zaytseva

Markey Cancer Center Faculty Publications

Perfluorooctanesulfonic acid (PFOS) is a widely recognized environment pollutant known for its high bio- accumulation potential and a long elimination half-life. Several studies have shown that PFOS can alter multiple biological pathways and negatively affect human health. Considering the direct exposure to the gastrointestinal (GI) tract to environmental pollutants, PFOS can potentially disrupt intestinal homeostasis. However, there is limited knowledge about the effect of PFOS exposure on normal intestinal tissues, and its contribution to GI- associated diseases remains to be determined. In this study, we examined the effect of PFOS exposure on the gene expression profile of intestinal tissues of …

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การพัฒนาจีโอพอลิเมอร์ซีเมนต์เพื่อใช้งานเป็นคอนกรีตอัดแน่นด้วยตัวเอง, ภัทรีวรรณ อิ่มสุวรรณ์ Jan 2024

การพัฒนาจีโอพอลิเมอร์ซีเมนต์เพื่อใช้งานเป็นคอนกรีตอัดแน่นด้วยตัวเอง, ภัทรีวรรณ อิ่มสุวรรณ์

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในงานวิจัยนี้เป็นการพัฒนาวิธีการเตรียมจีโอพอลิเมอร์ซีเมนต์ เพื่อใช้งานเป็นคอนกรีตอัดแน่นด้วยตัวเองโดยวิธีการเตรียมแบบจีโอพอลิเมอร์ซีเมนต์ เพื่อนำมาใช้ในงานก่อสร้างโดยใช้แนวคิดแบบเดียวกับการเตรียมปูนซีเมนต์ที่เมื่อทำการเติมน้ำลงไปผสมก็พร้อมใช้งาน ด้วยวิธีการนี้จะช่วยลดขั้นตอนและความยุ่งยากในการผสมเมื่อเทียบกับวิธีการเตรียมจีโอพอลิเมอร์แบบดั้งเดิม ในการศึกษานี้เถ้าลอยจะถูกนำมาผสมกับสารกระตุ้นด่างทั้งสามชนิด ได้แก่ โซเดียมเมต้าซิลิเกต แคลเซียมไฮดรอกไซด์ และโซเดียมไฮดรอกไซด์ ในอัตราส่วนต่างๆ ดังนี้ 49:49:2, 47.5:47.5:5, 46:46:8 และ 45:45:10 ส่วนผสมเหล่านี้ถูกนำไปบดด้วยลูกบดในช่วงเวลาที่แตกต่างกัน คือ 0, 6, 12 และ 24 ชั่วโมง จะได้ออกมาเป็นจีโอพอลิเมอร์ซีเมนต์ชนิดผง สารลดน้ำพิเศษในกลุ่มพอลิคาร์บอกซิเลตอีเทอร์จะถูกเติมลงไปปริมาณ 2% ของน้ำหนักเถ้าลอย ส่วนผสมทั้งหมดจะถูกนำมาผสมกับน้ำและหล่อในแม่พิมพ์ขนาด 2.5 x 2.5 x 2.5 ลูกบาศก์เซนติเมตร ก่อนนำไปบ่มที่อุณหภูมิห้องเป็นเวลา 24 ชั่วโมง และบ่มต่อเนื่องอีก 7 และ 28 วัน และนำตัวอย่างขีโอพอลิเมอร์ซีเมนต์ไปทำการทดสอบสมบัติทางกายภาพ สมบัติเชิงกล และสมบัติทางเคมีของจีโอพอลิเมอร์ซีเมนต์ที่เตรียมได้ ผลการทดสอบพบว่าระยะเวลาที่ทำการบดส่วนผสมและปริมาณของโซเดียมไฮดรอกไซด์ที่เติมลงในส่วนผสม ส่งผลต่อสมบัติต่างๆของจีโอพอลิเมอร์เป็นอย่างมาก โดยส่งผลกับระยะเวลาการก่อตัว ค่ากำลังอัด และอัตราการไหล ผลการศึกษาพบว่าการเพิ่มปริมาณโซเดียมไฮดรอกไซด์ส่งผลให้ค่ากำลังอัดสูงขึ้น และไม่ควรเกิน 8% โดยค่ากำลังอัดสูงสุดที่ได้คือ 21.16 MPa ในอัตราส่วนโซเดียมเมต้าซิลิเกต/แคลเซียมไฮดรอกไซด์/โซเดียมไฮดรอกไซด์ 46:46:8 ที่ผ่านการบดเป็นเวลา 24 ชั่วโมง

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Exploiting Quadratic Unconstrained Binary Optimization And Column Generation For Solving Vehicle Routing Problem With Discretized Time Windows, Krittin Phornsiricharoenphant Jan 2024

Exploiting Quadratic Unconstrained Binary Optimization And Column Generation For Solving Vehicle Routing Problem With Discretized Time Windows, Krittin Phornsiricharoenphant

Chulalongkorn University Theses and Dissertations (Chula ETD)

No abstract provided.

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Change Of Metal Oxidation State At High Temperature, Impact Of Temperature And Reactive Gases, Yegor Nikitin Jan 2024

Change Of Metal Oxidation State At High Temperature, Impact Of Temperature And Reactive Gases, Yegor Nikitin

Dissertations and Theses

The fundamental understanding of gas-solid reactions enables a wide range of applications to be developed and improved. Specifically, the use of metal-based materials is critical to ensuring robust, safe, and long-term operations. For example, in power systems where boilers are used to generate steam for heat or electricity generation the use of stainless metal alloys is critical to allow high quality steam to be produced in a very harsh environment. Alternatively, in catalysis, the use of metal doped heterogeneous catalysts are essential in achieving selectivity and conversion performance for chemical synthesis to emissions abatement. Typically, these metal alloys must withstand …

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Synthesis Of Novel 5-Aryl 2’-Deoxyuridine And 2’-Deoxycytidine Analogues, Kevin E. Persaud Jan 2024

Synthesis Of Novel 5-Aryl 2’-Deoxyuridine And 2’-Deoxycytidine Analogues, Kevin E. Persaud

Dissertations and Theses

Briefly, the following report details a synthetic route to prepare 5-phenyl-2’-deoxycytidine analogues. This multistep synthesis began with silyl protection of the 3’- and 5’-hydroxyl groups of 5-iodo-2’-deoxyuridine. Next, the installation of a phenyl ring at the C5 position of the nucleobase via a Suzuki-Miyaura cross-coupling reaction, yielding 5-phenyl-2’-deoxyuridine (5-PdU). After that, modification of the obtained 5-PdU at the C4 position was performed with benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate (BOP, a peptide-coupling agent) and a base (cesium carbonate) to activate the amide group of the uridine nucleobase for subsequent displacement with a variety of amines. Modification of the C4 position resulted in protected 5-phenyl-2’-deoxycytidine …

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Advancements In Forensic Analysis: Development Of Mass Spectrometric And Chemometric Approaches For The Identification Of Synthetic New Psychoactive Substances And Plant Materials, Mónica Ventura Jan 2024

Advancements In Forensic Analysis: Development Of Mass Spectrometric And Chemometric Approaches For The Identification Of Synthetic New Psychoactive Substances And Plant Materials, Mónica Ventura

Electronic Theses & Dissertations (2024 - present)

While forensic science is a well-established discipline, a number of federal agencies have highlighted challenges that continue to plague the field and the extent to which these challenges remain unaddressed. Examples are the illegal trade of wildlife timber and the drug epidemic. Characterization of these materials requires nuanced method development for compound determination, matrix material-specific protocols, and heavy use of expensive consumables. The application of a technique such as direct analysis in real time – high-resolution mass spectrometry (DART-HRMS) provides the opportunity to circumvent many of the challenges presented by conventional methods. In general, little to no sample preparation is …

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Gas Evolution Of A Nickel-Zinc Cell, Niklas Landgraf Jan 2024

Gas Evolution Of A Nickel-Zinc Cell, Niklas Landgraf

Graduate Theses/Dissertations

Batteries are a foundational technology in some of the industries most essential to humanity. Often, their advancement to achieve better performance impacts human lives positively. There are a wide variety of battery chemistries that have been utilized, and the differences in their properties have caused them to be used in many distinct niche applications. Nickel-Zinc (NiZn) batteries are desirable because of their recyclable materials, high cell voltage, and high cycle-life. However, it experiences undesirable shape-change of its electrode materials and gas production due to the electrolysis of the aqueous electrolyte. These can lead to a decrease in capacity over many …

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Assessing Interatomic Potentials For Molecular Dynamics Simulation Of Soybean Oil Pyrolysis, Tanner Garrett Rust Jan 2024

Assessing Interatomic Potentials For Molecular Dynamics Simulation Of Soybean Oil Pyrolysis, Tanner Garrett Rust

Graduate Theses/Dissertations

The world today relies on hydrocarbon combustion for many reasons, including its high energy density that provides ease of transportation. However, hydrocarbons sourced from fossil fuels are not expected to last forever. Biodiesel, a renewable alternative, has many attractive benefits but comes with other downsides. Biodiesel can gel in cold environments and may leave residue in an engine. Pyrolysis of biodiesel has shown promise in addressing these common detriments. Inducing pyrolysis on biodiesel feedstock (commonly soybean oil in the USA) would be an attractive option presuming it continues to produce fossil fuel analogs similar to biodiesel pyrolysis. Herein, Langevin molecular …

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Introducing Ordered Silicon Vacancies Into Wsi2, Grace M. Atkins Jan 2024

Introducing Ordered Silicon Vacancies Into Wsi2, Grace M. Atkins

Graduate Theses/Dissertations

Thermoelectric materials are very useful in industry due to their unique ability to convert waste heat into electricity. One such reported thermoelectric material is rhenium silicide (ReSi1.75▯0.25), resulting from ordered silicon vacancies in its crystal structure. The purpose of this project is to dope tungsten silicide (WSi2) with more electron rich elements to find a ternary silicide with a similar crystal structure to ReSi1.75▯0.25, in order to synthesize a less expensive thermoelectric material. Two synthesis methods are used in this project to dope WSi2. Powder x-ray diffraction (XRD) …

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Compton Scattering Of Mammographic Soft X-Ray Beams By Alkali And Transition Metal Salt Filters Produce X-Ray Interference Zones That May Have Treatment Potential For Localized Cancer Lesions, Subhendra N. Sarkar, Eric Lobel, Sabina Rakhmatova, Derbie Desir, Somdat Kissoon, Daler Djuraev, Katie Tam Jan 2024

Compton Scattering Of Mammographic Soft X-Ray Beams By Alkali And Transition Metal Salt Filters Produce X-Ray Interference Zones That May Have Treatment Potential For Localized Cancer Lesions, Subhendra N. Sarkar, Eric Lobel, Sabina Rakhmatova, Derbie Desir, Somdat Kissoon, Daler Djuraev, Katie Tam

Publications and Research

In breast x-ray imaging scattered radiation adds 50% of harmful radiation dose from anisotropic Compton scattering mechanism. We have been working with double layered inorganic salt materials that can induce Compton scattering to the incident mammographic x ray beams (in 20-30 kVp range) with adequate isotropy (angular control). Typically metal nitrates and alkali halide salt layers are shown here to cause low energy radiation interference zones with high and low photon intensities and local flux heterogeneity in terms of flux covariance. Spatial variation of low energy photon flux creates concentrated and sparse radiation zones that may be used to induce …

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The Impact Of Fluorination On The Volatility Of A Series Of Lanthanide Complexes, Kh Mahfuzul Alam Jan 2024

The Impact Of Fluorination On The Volatility Of A Series Of Lanthanide Complexes, Kh Mahfuzul Alam

Dissertations and Theses

Volatile lanthanides have been proposed for applications such as chemical vapor deposition precursors and facilitating f-element separations. The latter is motivated by their broad use in technological applications. In collaboration with synthetic chemists, we studied Ln-complexes with functionalized forms of the bulky tris[(4-hydroxy-pentenylidene-2-imino)ethyl]amine (TRAC) ligand. Five ligands, labeled Yb(CH3,CH3TRAC), Yb(CH3,CF3TRAC), Yb(CF3,CF3TRAC), Yb(CF3,C3F7TRAC) and Nd(tbu,C3F7TRAC) were synthesized and volatile Ln complexes were obtained. However, the temperature at which they sublime was not sufficiently low for industrial applications. Therefore, this work examined the experimentally characterized Yb(CH3,CH3TRAC), Yb(CH3,CF3TRAC), Yb(CF3,CF3TRAC), Yb(CF3,C3F7TRAC) and Nd(tbu,C3F7TRAC) in detail. The importance of interactions between two neighboring molecules in …

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Activation Of Molecular Oxygen For The Selective Oxidation Of Alkenes Catalyzed By Hollow Mn3o4 Nanoparticles, Pranab Kumar Nandy Jan 2024

Activation Of Molecular Oxygen For The Selective Oxidation Of Alkenes Catalyzed By Hollow Mn3o4 Nanoparticles, Pranab Kumar Nandy

Dissertations and Theses

This dissertation describes two distinct projects: 1) hollow Mn3O4 nanoparticles for selective oxidation of alkenes with O2, and 2) investigation of chloro[2-(mesityl(quinoline-8-yl-κN)boryl]-3,5-dimethyl-phenyl}methyl-κC)palladium(II) for activation of C-F bonds in aryl fluorides. Hollow Mn3O4 nanoparticles were synthesized from the galvanic reaction between Cu2+ and MnO nanocrystals. The hollow Mn3O4 particles were characterized with transmission electron microscopy and powder X-ray diffraction. The particles have diameter of 31 nm and a hollow cavity of 16 nm. We investigated the role of the hollow Mn3O4 nanoparticles in the selective oxidation of organic substrates with molecular oxygen. The results indicate that the hollow Mn3O4 nanoparticles catalyze …

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Advancing Anti-Counterfeiting Approach Via The Development Of Functional Optical Materials, Zishen Yang Jan 2024

Advancing Anti-Counterfeiting Approach Via The Development Of Functional Optical Materials, Zishen Yang

Dissertations and Theses

Counterfeiting poses a significant threat to public health and safety, necessitating robust measures to combat it. Addressing this challenge requires the development of advanced materials and techniques, coupled with a comprehensive understanding of the obstacles inherent in anti-counterfeiting endeavors. Our study delved into two approaches for crafting anti-counterfeiting technologies: plasmonic and luminescence materials. We thoroughly examined the challenges associated with each method and proposed viable solutions. Notably, we devised a streamlined process for producing inkjet printable Surface-enhanced Raman Scattering (SERS) ink, enabling the creation of low-cost covert quick response (QR) codes with a high storage capacity. Access to the encoded …

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