Chemistry Commons^™

Determination Of Total Ammonia Nitrogen By Gas-Diffusion Flow Injection Analysis (Gd-Fia)-Spectrophotometry Using Minnieroot Flower (Ruellia Tuberosa) As Natural Reagent, Lani Artana Putri, Puspita Mufidah Sari, Hermin Sulistyarti, Akhmad Sabarudin, Erwin Sulistyo

Makara Journal of Science

Total ammonia nitrogen (TAN) is a pollutant agent found in water and generated from the metabolisms of living organisms and the decomposition of organic matter. This research aims to develop an efficient, low-cost, and environmentally friendly TAN analysis method. The principle of this method is based on the reaction of TAN injected in the donor stream with NaOH to form alkaline gaseous ammonia. The gaseous ammonia diffuses through a hydrophobic membrane into an acceptor stream containing Ruellia tuberosa extract. The presence of NH₃ gas in the acceptor stream changes the extract color from pinkish to green, which is monitored …

Compatibility Of Crude Oil Blends─Processing Issues Related To Asphaltene Precipitation, Methods Of Instability Prediction─A Review, Krzysztof Bambinek, Andrzej Przyjazny, Grzegorz Boczkaj

Natural Sciences Publications

Processing crude oil of variable composition, especially due to the need to process crude oil blends obtained from various sources, presents a tremendous process challenge. This is mainly due to the destabilization of the colloidal system manifested mostly by the precipitation of the asphaltene fraction. The precipitation of asphaltenes from crude oil is a serious problem during extraction, transport, and processing. In the latter case, engineers and scientists have spent a lot of time determining what mechanisms are conducive to the occurrence of this phenomenon. On the one hand, there was a scientific curiosity about the principles of the nanoworld …

Metallacycle-Mediated Cross-Coupling As An Enabling Tool For Studies In Carbocycle Synthesis And Functionalization, Adam Barry Millham

Dartmouth College Ph.D Dissertations

Natural products, specifically complex, carbocyclic natural products, have served as the inspiration for novel methods development for decades. Over that time, metallacycle-mediated cross-coupling has arisen as a powerful means for the synthesis of fused carbocycles. This work details three methods for the synthesis and functionalization of carbocyclic motifs that have been enabled by Ti-mediated cross-coupling reactions. The first of these studies include a complementary method to the Pauson–Khand reaction for the synthesis of highly substituted cyclopentenones via Ti-mediated alkyne–β-ketoester coupling. The second project, a modern approach to steroidal tetracycles, will be discussed that features: (1) an alkoxide-directed metallacycle-mediated [2+2+2] annulation …

A Coherence-Colored Look Inside Reverse Micelles: Advancing Magnetic Resonance Relaxometry To Characterize Internal Water Pool Dynamics, Alec Beaton

Dissertations - ALL

Traditional data acquisition methods in Nuclear Magnetic Resonance (NMR) collect a subset of the total amount of generated data and discard the rest. In this work, a modified approach toward NMR data acquisition and analysis is formalized and applied in a series of different contexts, ultimately illustrating the utility of collecting and considering this traditionally discarded data. In particular, it is shown that this approach both facilitates and improves NMR data acquisition capabilities at low field (15 MHz), enabling one to overcome challenges arising from, for example, fluctuations in the static magnetic field.With these developments in hand, the dual resonance …

Arginine Methylation Of The Pgc-1Α C‑Terminus Is Temperature- Dependent, Meryl Mendoz, Mariel Mendoza, Tiffany Lubrino, Sidney Briski, Immaculeta Osuji, Janielle Cuala, Brendan Ly, Ivan Ocegueda, Harvey Peralta, Benjamin A. Garcia, Cecilia Zurita-Lopez

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We set out to determine whether the C-terminus (amino acids 481–798) of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α, UniProt Q9UBK2), a regulatory metabolic protein involved in mitochondrial biogenesis, and respiration, is an arginine methyltransferase substrate. Arginine methylation by protein arginine methyltransferases (PRMTs) alters protein function and thus contributes to various cellular processes. In addition to confirming methylation of the C-terminus by PRMT1 as described in the literature, we have identified methylation by another member of the PRMT family, PRMT7. We performed in vitro methylation reactions using recombinant mammalian PRMT7 and PRMT1 at 37, 30, 21, 18, and 4 °C. …

Effect Of Temperature And Sodium Chloride Addition On The Conductivity Of Sodium (Polystyrene Sulfonate) Aqueous Solutions, Saida Asfour, Ahmed Ayyad, Fahed Takrori

Hebron University Research Journal-A (Natural Sciences) - (مجلة جامعة الخليل للبحوث- أ (العلوم الطبيعيه

The conductivity of sodium (polystyrene sulfonate) (NaPSS) aqueous solutions as a function of NaPSS concentration 0.15 g – 2.0 g NaPSS in 100 mL of distilled water, sodium chloride concentration (NaCl) in the range of 0.1 M - 0.4 M and in temperature range of 278 K – 328 K have been studied. The study found that conductivity increases with increasing NaPSS concentration both in pure water and in salt solution. It is also found that conductivity increases with increasing either NaCl concentration or temperature. The interesting finding here is that additivity rule, that the conductivity of the polyelectrolyte kps …

Post-Translational Modifications Of Cyclophilin D Fine-Tune Its Conformational Dynamics And Activity: Implications For Its Mitochondrial Function, Jacques Kumutima, Xin-Qiu Joe Yao, Donald Hamelberg

Chemistry Faculty Publications

Mitochondria are the powerhouse of a cell, whose disruption due to mitochondrial pore opening can cause cell death, leading to necrosis and many other diseases. The peptidyl-prolyl cis–trans isomerase cyclophilin D (CypD) is a key player in the regulation of the mitochondrial pore. The activity of CypD can be modulated by the post-translational modification (PTM). However, the detailed mechanism of this functional modulation is not well understood. Here, we investigate the catalytic mechanism of unmodified and modified CypD by calculating the reaction free energy profiles and characterizing the function-related conformational dynamics using molecular dynamics simulations and associated analyses. Our results …

Medicinal Bismuth: Bismuth-Organic Frameworks As Pharmaceutically Privileged Compounds, Shaila A. Shetu, Luis M. Sanchez-Palestino, Gildardo Rivera-Sanchez, Debasish Bandyopadhyay

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Historically organometallic compounds have been used to cure certain diseases with limited applications. Although bismuth belongs to the category of heavy metals, many of its derivatives have found applications in modern drug discovery research, mainly because of its low toxicity and higher bioavailability. Being an eco-friendly mild Lewis acid, compounds having bismuth as a central atom are capable of binding several proteins in humans and other species. Bismuth complexes demonstrated antibacterial potential in syphilis, diarrhea, gastritis, and colitis. Apart from antibacterial activities, bismuth compounds exhibited anticancer, antileishmanial, and some extent of antifungal and other medicinal properties. This article discusses major …

Bio-Based Uv-Curable Films And The Effect Of Bio-Content On The Properties Of The Films, Sahilkumar Chaudhary

Electronic Theses & Dissertations

The use of renewable resources in film formation has become a new focal point for industry because it is abundantly available and has less carbon emission during production than traditional ones. This has drawn researchers to investigate the functionality of bio-based raw materials and their end-usage. By modifying their chemical structures, the properties of these films like thermal resistance, impact resistance, and chemical resistance can be increased. In this research, limonene was used as a partial replacement for petroleum-based chemicals in film formation. A two-step chemical process was carried out to modify the limonene and the final product was used …

Possible Overestimation Of Nitrogen Dioxide Outgassing During The Beirut 2020 Explosion, Ashraf Farahat, Nayla El-Kork, Ramesh P. Singh, Feng Jing

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

On 4 August 2020, a strong explosion occurred near the Beirut seaport, Lebanon and killed more than 200 people and damaged numerous buildings in the vicinity. As Amonium Nitrate (AN) caused the explosion, many studies claimed the release of large amounts of NO₂ in the atmosphere may have resulted in a health hazard in Beirut and the vicinity. In order to reasonably evaluate the significance of NO₂ amounts released in the atmosphere, it is important to investigate the spatio-temporal distribution of NO₂ during and after the blast and compare it to the average day-to-day background emissions from …

Speciated Isotope Dilution Mass Spectrometry In Combination With Thor’S Hammer Metaspike Technology For The Assessment Of Low-Level Biomarkers For Human Health Evaluation, Ashley Ebert

Electronic Theses and Dissertations

Our research team has been focused on quantifying important biological analytes in human blood samples to delineate the biochemical processes underlying certain states of dysfunction and evaluate treatment efficacy. These efforts have been guided by laboratory measurements with the input of medical experts. Speciated isotope dilution mass spectrometry (SIDMS) explained in detail in EPA Method 6800 has been successfully applied in the quantification of an important biomarker analyte for immune function and detoxification processes: glutathione. Past research has proven the molecule a biomarker for autism spectrum disorder (ASD) in the form of the reduced/oxidized glutathione (GSH/GSSG) ratio, and literature has …

Quantum Computations And Molecular Dynamics Simulations: From The Fundamentals Of Antimicrobial Resistance To Neurological Diseases, Angel Tamez

Electronic Theses and Dissertations

Biophysical phenomena are modeled using a combination of quantum and classical methods to interpret and supplement three distinct and diverse problems in this dissertation. In the first project, decarboxylation reactions are ubiquitous across chemical and biological disciplines, yet the origin of non-catalytic solvent effects remains elusive. Specific solvent structure and energetics have not been well described for the monoanion of malonate, nor corrected from the gas-phase charge-assisted intramolecular hydrogen bond model known as “pseudochair”. In the aqueous phase, a low-lying energy conformer known as the “orthogonal conformation” is computed to be preferred by a three-water cluster of hydrogen bonding over …

Acetylacetone Oxidation At Room Temperature: A Multiplexed Photoionization Mass Spectrometric Investigation, Study Of The Russell Intermediates In Gas Phase Reactions, And The Investigation Of Oxidation Reaction Products Of Ethanol At Room Temperature, Sara Gallarati

Master's Theses

This thesis presents the combustion study of acetyl acetone using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at 298 K. The experiments were performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source of the Lawrence Berkeley National Laboratory. The reaction of acetyl acetone with chlorine (Cl) radicals was analyzed based on their photoionization spectra and reaction kinetic profiles.

Additionally, a study of the Russell intermediate has been performed. Previous to experimentation at the Advanced Light Source, computational analysis has been investigated to evaluate compounds that could possibly lead to the formation of a stable species. The …

Chemical Elements, Flavor Chemicals, And Nicotine In Unused And Used Electronic Cigarettes Aged 5–10 Years And Effects Of Ph, Monique Williams, Wentai Luo, Kevin J. Mcwhirter, Omeka Ikegbu, Prue Talbot

Chemistry Faculty Publications and Presentations

The concentrations of elements/metals, nicotine, flavor chemicals and acids were compared in the e-liquids of unused and used first-generation electronic cigarettes (ECs) that were stored for 5–10 years. Metal analysis was performed using inductively coupled plasma optical emission spectroscopy; nicotine and flavor chemical analyses were performed using gas chromatography/mass spectroscopy. Of the 22 elements analyzed, 10 (aluminum, chromium, copper, iron, lead, nickel, selenium, silicon, tin, zinc) were often found in the e-liquids. Five elements had the highest average concentrations: copper (1161.6 mg/L), zinc (295.8 mg/L), tin (287.6 mg/L), nickel (71.1 mg/L), and lead (50.3 mg/L). Nicotine concentrations were always lower …

Sunflower Oil-Based Polyol In Flame-Retardant Rigid Polyurethane Foams, Magdalene Asare

Electronic Theses & Dissertations

The current shift from solely depending on petroleum sources to seeking renewable alternatives is due to their fast depletion, spike in prices, and the need to reduce our carbon footprint. For instance, the polyurethane industry currently calls for renewable and less toxic polyols and isocyanates for their synthesis over the traditionally used ones. To tackle an aspect of this matter, this work investigates the generation of polyol from sunflower oil, and further probes their use in rigid foams, one of the widely utilized polyurethanes. Epoxidation and ring-opening reactions were used to convert the sunflower oil into a more reactive form, …

The Facile Preparation Of Bis(Imino)Pyridine Complexes Via Mechanochemistry And Inorganic Synthons Via Benign Reductants, Thomas Shaw

Electronic Theses and Dissertations, 2020-2023

This thesis is comprised of two key themes: (i) leveraging mechanochemical synthetic methods for the green preparation of bis(imino)pyridine ligands and associated first row transition metal coordination complexes, and (ii) the preparation and characterization of both historic and novel mid-valent inorganic synthons via the use of dimethylphenylsilane as a stoichiometric reducing agent. The first portion of this thesis highlights the utilization of solvent-free vibratory ball-milling in lieu of traditional, solvent-based refluxes. A variety of both bis(imino)pyridine ligands and complexes were formed in drastically reduced timeframes with solvent-economical work-up procedures. This methodology was also leveraged for the isolation of acetyl(imino)pyridine ligands …

Synthesis And Application Of Functional Unimolecular [N]Catenanes In Novel Polymeric Materials, Mark Andrew Nosiglia

Arts & Sciences Graduate Student Theses and Dissertations

Mechanically interlocked molecules (MIMs) possess unique architectures and non-traditional degrees of freedom that arise from well-defined topologies that are achieved through precise mechanical bonding. Incorporation of MIMs into materials can thus provide an avenue to discover new and emergent macroscale properties. Here, the synthesis of a phenanthroline-based [2]catenane crosslinker and its incorporation into polyacrylate organogels is described. Specifically, Cu(I) metalation and de-metalation was used as a post-gelation strategy to tune the mechanical properties of a gel by controlling the conformational motions of integrated MIMs. The organogels were prepared via thermally initiated free radical polymerization, and Cu(I) metal was added in …

Functionalized Plasmonic Nanostructures For Ultrasensitive Single Cell Analysis, Priya Rathi

Arts & Sciences Graduate Student Theses and Dissertations

Ultrasensitive detection and quantification of soluble, secreted and cell surface-bound proteins is critical for advancing our understanding of cellular systems, enabling effective drug development, novel therapies, and bio-diagnostics. However, exiting technologies are largely limited by their sensitivity, making the detection and quantification of low-abundant proteins extremely challenging. This forms a major barrier in various fields of biology and biomedical sciences. In this work, we introduce novel cellular analysis methodologies based on plasmon-enhanced fluorescence for analyzing cell structure and probing surface and secreted proteins from cells. In the first part, we introduce plasmon-enhanced expansion microscopy and demonstrate the effectiveness of employing …

Development Of Novel Nucleophile-Intercepted Beckmann Fragmentations And Progress Toward The Total Synthesis Of 2(S)-Cathafoline, Evan M. Dunkley

Dartmouth College Master’s Theses

This thesis is comprised of two chapters, the first being the discovery of a novel nucleophile-intercepted Beckmann fragmentation of [2.2.1] indoline systems that resulted in highly stereo- and regioselective reactions. Chapter one details the exploration of this reaction as well as its relevant background information detailing its significance. Chapter two describes the application of the novel nucleophile-intercepted Beckmann fragmentation in the context of a total synthesis of akuammilline alkaloid 2(S)-cathafoline. While the target natural product was never synthesized, unpredicted reactivity resulted in interesting discoveries worthy of discussion.

Toward Enhancing The Synthesis Of Renewable Polymers: Feedstock Conversions And Functionalizable Copolymers, Tedd Casey Wiessner

Arts & Sciences Graduate Student Theses and Dissertations

This thesis describes research under the rubric of the Center for Sustainable Polymers that is aimed at two separate goals. The goal of the first project (Chapters 1 and 2) was to develop a deeper mechanistic understanding of a method for the synthesis of linear α-olefins, while the second aimed at synthesizing statistical copolymers that incorporate olefin-containing monomers through ring-opening transesterification polymerization and showing that these copolymers could be functionalized. In Chapter 1, published methods for the conversion of fatty acids to linear α-olefins are reviewed to provide context for the mechanistic work we accomplished (Chapter 2). In Chapter 2 …

The Effect Of Ionization Density In Applications Of Radiation Detection, Dosimetry, And Therapy, Daniel Mulrow

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation covers a wide range of topics but is linked by the common theme of radiation interacting with materials and studying the result of those interactions. The introduction describes the fundamentals of how radiation interacts with material and how we are able to detect that radiation and the application of how we use those interactions in radiation oncology. The thesis starts with a chapter detailing the temperature dependence of the photophysics in two organic scintillators. This chapter is the foundation for a future study that will look the degree to which these scintillators can distinguish between gammas and neutrons …

Local Spectroscopy Data Infrastructure: Solid State Nmr Crystallography With Experiment, First-Principal Analysis And Machine Learning, He Sun

Arts & Sciences Graduate Student Theses and Dissertations

Solid-state magnetic resonance (SSNMR) spectroscopy is a powerful tool for obtaining precise information about the local bonding and morphology of materials. The detailed local structure of crystalline materials cannot be easily solved by traditional experimental methods such as X-ray diffraction (XRD). SSNMR combined with first principal calculation methods such as density functional theory (DFT) can be of great use in this research area. The methodology that is called “NMR crystallography” today has been widely applied to the determination of a wide range of solid materials with an increasing amount of computationally simulated NMR spectra. The construction of a well-established computational …

Development Of Redox-Responsive Phenazine-Based Foldamers. Acylative Kinetic Resolution Of Hydroxamic Acids, Jingwei Yin

Arts & Sciences Graduate Student Theses and Dissertations

Two different research directions have been presented in this thesis. The first project is about phenazine-based foldamers as molecular actuators. Researchers have been interested in the design and synthesis of foldamers and molecular actuators for years. We began our exploration by demonstrating that phenazine-1,6-dicarboxamides can function as redox-responsive molecular switches. We then designed and synthesized two generations of phenazine-based interleafed foldamers and studied their stability and redox behaviors under chemical and electrochemical conditions. In the second project, we have developed the first acylative kinetic resolution on hydroxamic acids. Although chiral hydroxamic acids have extensive applications, synthetic methods towards them are …

Tracking Reducing Equivalents Between Cellular Compartments To Understand The Metabolic Demands Of Proliferation, Yahui Wang

Arts & Sciences Graduate Student Theses and Dissertations

Proliferating cancer cells compartmentalize metabolic reactions, many of which require reducing equivalents. This compartmentalization is functionally important, but it is challenging to study with current technologies. As a consequence, our understanding of proliferating metabolism has been limited. Here, I developed an approach to track reducing equivalents between cellular compartments. By applying this method to a panel of different cell lines under various conditions, I investigated a dysregulated metabolic phenotype in proliferating cells known as “aerobic glycolysis”. Aerobic glycolysis is characterized by an elevated rate of glucose fermentation to lactate irrespective of oxygen availability. Using the NCI-60 cell lines, I first …

Non-Canonical Beta-Lactam Antibiotics, Brett Wesley Virgin-Downey

Arts & Sciences Graduate Student Theses and Dissertations

In canonical β-Lactam antibiotics, such as penicillin, the strained nature of the β-Lactam ring leads to acylation of the catalytic serine in the active site of transpeptidases. In 2018, our lab reported a novel mechanism for monocyclic β-lactam antibiotics in the inhibition of glutamine synthetase (GS) by a natural product, tabtoxinine-β-lactam (TβL) using a 3-hydroxy-β-lactam pharmacophore. This work aims to generalize the β-lactam scaffold from TβL to act as a warhead against ATP-dependent carboxylate-amine ligase enzymes, with dihydrofolate synthetase (DHFS) as the test case. A pure 3-hydroxy-β-lactam warhead was synthesized and ligated both chemically and chemoenzymatically to different pteridine mimics. …

Effects Of Surface Ligation On Charge Extraction From Wurtzite Cadmium Selenide Quantum Platelets And Quantum Belts, Hailey Meyer

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation presents the synthesis of flat, colloidal wurtzite CdSe quantum platelets and quantum belts for ligand exchange to novel and existing organic and inorganic L-, X-, and Z- type ligands. Use of these ligands in conjunction with the semiconductor nanocrystals allows for examination of their ligand exchange abilities, photoluminescence quenching efficiencies, and charge transfer properties.First, zinc and cadmium dithiocarbamate compounds [M(S2CNR1R2)2] are used as ligands on wurtzite CdSe quantum belts. Complete ligand exchange is achieved when the belts are initially ligated with Cd(oleate)2, a Z-type ligand, prior to the exchange, as opposed to n-octylamine or ammonia, which are both …

Utilizing An Α,Β-Unsaturated Dicarboxylic Acid For A Defect Initiated Residue Removal During Cu Post-Chemical Mechanical Planarization Cleaning, Abigail L. Dudek, Kiana A. Cahue, Adam T. Caridi, Tatiana R. Cahue, Jason J. Keleher

Chemistry Department Faculty Articles

The development of post-Chemical Mechanical Planarization (p-CMP) cleaning processes is critical for the continued miniaturization of Integrated Circuit (IC) and logic device architecture. In order for further extension of Moore’s Law the minimization of critical defects is essential. This work focuses on the development of surface-active cleaning chemistries via the implementation of an α, β-unsaturated dicarboxylic acid additive to create synergy at the liquid-brush-wafer interface. More specifically, the implementation of Itaconic Acid (ItA) will chemically activate an organic residue (i.e., Cu(I)-BTA film) resulting in effective removal at significantly reduced CoF. This work demonstrates that the conjugated structure present in ItA …

Uv-Light-Tunable P-/N-Type Chemiresistive Gas Sensors Based On Quasi-1d Tis3 Nanoribbons: Detection Of Isopropanol At Ppm Concentrations, Victor V. Sysoev, Andrey V. Lashkov, Alexey Lipatov, Ilya A. Plugin, Michael Bruns, Dirk Fuchs, Alexey S. Varezhnikov, Mustahsin Adib, Martin Sommer, Alexander Sinitskii

Department of Chemistry: Faculty Publications

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS₃) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS₃ nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as …

Water Management And Corrosion Performance From Protective Polymer Coatings With Spatially Controlled Hydrophilic Domains, Jessica M. Davison

Dissertations

Metallic corrosion has become an annual multibillion-dollar problem for the industrialized world and global contamination issue through the process of repair, removing, and reapplying protective coatings. Typical corrosion resistant coatings are comprised of polymeric coating layers with anti-corrosive pigments, plasticizers, sacrificial additives, and/or other formulation materials, which are formulated to prevent, detect, and manage corrosion. Our counterintuitive approach was to improve upon the understanding of how, when, where, and why environmental contaminants (reactants, mainly water and electrolytes) driving corrosion, propagate and accumulate as localized hydrophilicity shifts within a model polymer coated substrate. Herein, hydrogel particles (HGP) were synthesized of defines …

Enhanced Structural Control Of Soft-Templated Mesoporous Inorganic Thin Films By Inert Processing Conditions, Maximilliano Jesus Jara Fornerod, Alberto Alvarez-Fernandez, Eric R. Williams, Miximillian W.A. Skoda, Beatriz Prieto-Simon, Nicolas H. Voelcker, Morgan Stefik, Marc-Oliver Coppens, Stefan Guldin

Faculty Publications

Mesoporous thin films are widely used for applications in need of high surface area and efficient mass and charge transport properties. A well-established fabrication process involves the supramolecular assembly of organic molecules (e.g., block copolymers and surfactants) with inorganic materials obtained by sol-gel chemistry. Typically, subsequent calcination in air removes the organic template and reveals the porous inorganic network. A significant challenge for such coatings is the anisotropic shrinkage due to the volume contraction related to solvent evaporation, inorganic condensation, and template removal, affecting the final porosity as well as pore shape, size, arrangement, and accessibility. Here, we show that …