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2019

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Articles 571 - 600 of 1773

Full-Text Articles in Chemistry

Electrocatalytic Nanomaterials For Reduction Of Hydrogen Peroxide As Potential Radioprotectors, Rui-Hong Jia, Jin-Xuan Zhang, Xiao-Dong Zhang, Mei-Xian Li Jun 2019

Electrocatalytic Nanomaterials For Reduction Of Hydrogen Peroxide As Potential Radioprotectors, Rui-Hong Jia, Jin-Xuan Zhang, Xiao-Dong Zhang, Mei-Xian Li

Journal of Electrochemistry

Nanomaterials have shown many potential application prospects in the biomedical field, such as medical imaging, drug delivery and biosensing due to their unique physical and chemical properties. In this review we focus on nanomaterials that have shown not only abilities of radiation protection, but also good electrocatalytic activities toward reduction reactions of hydrogen peroxide and oxygen. We discuss the abilities of radiation protection of these nanomaterials that are ascribed to their enzyme-like activities because their catalytic properties provide an effective pathway for scavenging free radicals in vivo via rapid reactions with reactive oxygen species. We also provide insights into electrocatalytic …

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Electrochemical Biosensors For Wastewater-Based Epidemiology, Yu-Wei Pan, Kang Mao, Franziska Tuerk, Zhu-Gen Yang Jun 2019

Electrochemical Biosensors For Wastewater-Based Epidemiology, Yu-Wei Pan, Kang Mao, Franziska Tuerk, Zhu-Gen Yang

Journal of Electrochemistry

Wastewater-based epidemiology (WBE) has been shown to be an innovative approach for evaluation of drug use trends and public health assessment by quantifying drug residues and/or metabolites (so-called biomarkers) in wastewater collected in a local treatment plant. Community sewage sensors have been proposed and demonstrated to be powerful tools for the analysis of sewage biomarkers. In particular, electrochemical biosensors have emerged as a rapid method for the analysis of biomarkers and pathogens in wastewater due to low cost, minimal sample processing and the ability to test in the field. It has been widely used for biomedical diagnosis, environmental monitoring and …

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Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou Jun 2019

Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou

Journal of Electrochemistry

Single particle impact electrochemistry (SPIEC) has grown rapidly in recent years and shown great promise in the analysis of nanoparticle properties as well as the detection of biomolecules including DNA, RNA, protein, enzyme, bacteria, virus, vesicles and others. This minireview summarizes recent advances in electroanalytical applications of SPIEC according to different analytical methods, i.e., direct electrolysis of nanoparticles or labeled nanoparticles, direct electrolysis of soft particles encapsulated redox molecule, indirect electrochemistry of particles, area and diffusion blocking, and changes in current magnitude and collision frequency.

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Cysteine And Cystamine Co-Self-Assembled Monolayers For In Vivo Detection Of Ascorbic Acid, Yue Zhang, Tao-Tao Feng, Wen-Liang Ji, Mei-Ning Zhang Jun 2019

Cysteine And Cystamine Co-Self-Assembled Monolayers For In Vivo Detection Of Ascorbic Acid, Yue Zhang, Tao-Tao Feng, Wen-Liang Ji, Mei-Ning Zhang

Journal of Electrochemistry

Self-assembled monolayers (SAMs), which form highly ordered monolayers on the electrode surface through the gold-suffer bond, have attracted much attention in recent years. This stable layer not only can regulate the wettable properties of surface, but also can act as a promoter towards redox-active molecules. Here, we developed a simple and effective method to construct cysteine and cystamine co-self-assembled monolayer on gold microelectrode for  in vivo detection of ascorbic acid (AA). The molar ratio at 1:1 of mixed monolayer has been found the optimum to enhance the electron-transfer kinetics of AA oxidation at low potential (ca. 0.10 V), meanwhile, it …

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Research Progresses In Structural Modulation And Electrochemiluminescence Of Supertetrahedral Chalcogenide Clusters, Gang Lei, Yang Liu Jun 2019

Research Progresses In Structural Modulation And Electrochemiluminescence Of Supertetrahedral Chalcogenide Clusters, Gang Lei, Yang Liu

Journal of Electrochemistry

Electrochemiluminescence (ECL) exhibits a broad application prospect in the field of biological analysis due to its unique performance features, and the exploitation of high efficient ECL reagents offers an important tool for the development of sensors with excellent performance and practical clinical applications. Open-framework supertetrahedral chalcogenide clusters both possess the porous structure of molecular sieve and the excellent optical properties of the semiconductor, so it has attracted more and more attention in ECL analysis. Different from the traditional semiconductor quantum dots, the structure and composition of supertetrahedral chalcogenide clusters can be accurately controlled at the atomic level, and supertetrahedral chalcogenide …

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Current Statuses And Challenges Of Wearable, Flexible Electronic Sensors And Energy Storage Devices, Zhong-Qian Song, Fang-Jie Han, Hui-Jun Kong, Jia-Nan Xu, Yu Bao, Dong-Xue Han, Li Niu Jun 2019

Current Statuses And Challenges Of Wearable, Flexible Electronic Sensors And Energy Storage Devices, Zhong-Qian Song, Fang-Jie Han, Hui-Jun Kong, Jia-Nan Xu, Yu Bao, Dong-Xue Han, Li Niu

Journal of Electrochemistry

With the developments in the internet of things, artificial intelligence and human-computer interaction technology, soft, flexible and wearable electronic devices provide a novel platform for monitoring of the human vital signs, and recognition of human behaviors to connect human being and machine without consciousness. Recent progresses about wearable and flexible electronics that can provide accurate, non-invasive, long-term and continuous monitoring of human vital sings including pulse, temperature, skin activities, breathing and heart rate are summarized. The working mechanisms, current statuses and challenges in temperature sensor, strain sensor and pressure sensor are discussed. The review concludes with a prospect of current …

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Correlated Optical Imaging And Electrochemical Recording For Studying Single Nanoparticle Collisions, Lin-Lin Sun, Wei Wang, Hong-Yuan Chen Jun 2019

Correlated Optical Imaging And Electrochemical Recording For Studying Single Nanoparticle Collisions, Lin-Lin Sun, Wei Wang, Hong-Yuan Chen

Journal of Electrochemistry

With the development of nano-fabrications in recent years, a novel strategy based on random collisions of single electroactive nanoparticles (NPs) onto an inert ultramicroelectrode (UME) has been emerged in the field of nanoelectrochemistry, and named as single nanoparticles collisions (SNCs). The technique uses a chronoamperometric method to detect transient current generated by random collisions of single NPs onto an UME. By analyzing the current signal, one could study the properties of single NPs. Although this technique can detect electrochemical or electrocatalytic currents of a single NP, the traditional SNCs technology lacks necessary spatial resolution to identify and characterize a specific …

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Multiscale Approach For The Optimization Of Ketones Production From Carboxylic Acids By The Decarboxylative Ketonization Reaction, Alexey Ignatchenko Jun 2019

Multiscale Approach For The Optimization Of Ketones Production From Carboxylic Acids By The Decarboxylative Ketonization Reaction, Alexey Ignatchenko

Chemistry Faculty/Staff Publications

A historical perspective on the advancement of the decarboxylative ketonization catalysis research and development in industry and in academia is given with the focus on the past twenty years. Reviewed topics cover results of the most recent computational modeling and isotopic labeling studies, fine details of the reaction mechanism, experimental evidence for the existence of hidden degenerate reactions, explanation of the reaction rate inhibition, and reversibility of the reaction course. For this reaction, characterized strictly as acid-base catalysis, the origin of the misconception about the requirement for metal oxide catalysts being reducible and oxidizable is explained. Technology solutions for the …

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Using Molecular Dynamics To Study Qs21 Interactions And Penetration Of Lipid-Cholesterol Bilayers, Sarai Guerrero, Mikko Karttunen Jun 2019

Using Molecular Dynamics To Study Qs21 Interactions And Penetration Of Lipid-Cholesterol Bilayers, Sarai Guerrero, Mikko Karttunen

Western Research Forum

Saponins have been used as adjuvant agents for decades in vaccines and therapies, but none are as well studied or heavily used as QS-21. This achievement is notwithstanding the fact that QS-21 usage is limited by its stability, toxicity, and scarcity. These shortcomings have only pushed researchers to develop and experiment with artificial recreations of the saponin to harness its unique benefits. A considerable number of research hours have been poured into this topic, but like QS-21 there is a shortcoming here as well. The number of articles that look at QS-21 interactions with the bilayer or the conditions under …

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Swelling Kinetics Of Cationite Ku-2x4 In Solutions Of Different Concentrations Of Hydrochloric Acid, Kh.T. Trobov, N.B. Ferapontov, M.G. Tokmachov, G.Kh. Tursunova Jun 2019

Swelling Kinetics Of Cationite Ku-2x4 In Solutions Of Different Concentrations Of Hydrochloric Acid, Kh.T. Trobov, N.B. Ferapontov, M.G. Tokmachov, G.Kh. Tursunova

Scientific Journal of Samarkand University

From the position of the heterophase model of the structure of polymer gels, the kinetics of swelling of the cation exchanger KU-2x4 in HCl solutions of different concentrations was investigated. It is proved that the swelling proceeds according to the kinetic equations of the first-order reaction.

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Study Textural, Physico-Chemical And Sorption Characteristics Of Activated Coal Prepared From Walnut, A.N. Mukhamadiyev, Sh.M. Sayitqulov, N.K. Mukhamadiyev Jun 2019

Study Textural, Physico-Chemical And Sorption Characteristics Of Activated Coal Prepared From Walnut, A.N. Mukhamadiyev, Sh.M. Sayitqulov, N.K. Mukhamadiyev

Scientific Journal of Samarkand University

In this paperbased on electron microscopic study of the samples of activated carbon obtained from walnut shells is shown that their structures have a developed porous surface. According to the results of semi-quantitative elemental analysis of the adsorbents investigated by the method of energy dispersive X-ray spectroscopy (EDAX), it was found that the adsorbent based on the walnut shells has the highest carbon content (92.3%). The activated carbon has the following characteristics: the moisture content is 6.9%, the total pore volume on water is 0.69 cm 3 /g, the pH of the aqueous extract is 6.9, the bulk density is …

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Nitrogen Heterocycles Form Peptide Nucleic Acid Precursors In Complex Prebiotic Mixtures, Laura E. Rodriguez, Christopher H. House, Karen E. Smith, Melissa R. Roberts, Michael P. Callahan Jun 2019

Nitrogen Heterocycles Form Peptide Nucleic Acid Precursors In Complex Prebiotic Mixtures, Laura E. Rodriguez, Christopher H. House, Karen E. Smith, Melissa R. Roberts, Michael P. Callahan

Chemistry and Biochemistry Faculty Publications and Presentations

The ability to store information is believed to have been crucial for the origin and evolution of life; however, little is known about the genetic polymers relevant to abiogenesis. Nitrogen heterocycles (N-heterocycles) are plausible components of such polymers as they may have been readily available on early Earth and are the means by which the extant genetic macromolecules RNA and DNA store information. Here, we report the reactivity of numerous N-heterocycles in highly complex mixtures, which were generated using a Miller-Urey spark discharge apparatus with either a reducing or neutral atmosphere, to investigate how N-heterocycles are modified under plausible prebiotic …

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Synthesis, Discovery And Delivery Of Therapeutic Natural Products And Analogs, Zachary P. Shultz Jun 2019

Synthesis, Discovery And Delivery Of Therapeutic Natural Products And Analogs, Zachary P. Shultz

USF Tampa Graduate Theses and Dissertations

Small molecule drug discovery relies heavily on synthetic organic chemistry to develop novel chemical entities that elicit desirable therapeutic effects. The development of targeted chemical syntheses is of paramount importance to access molecules for biological evaluation and is usually considered the bottleneck in most drug discovery campaigns. Targets for chemical syntheses commonly draw inspiration from molecules of natural origin. Nature harbors a wealth of chemical diversity that has established itself over millions of years through chemical and biological evolution. Organisms have an inherent ability to protect themselves from predators and harmful environments. In doing so, many of them evolve to …

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Correlating Lipid Membrane Permeabilities Of Imidazolium Ionic Liquids With Their Cytotoxicities On Yeast, Bacterial, And Mammalian Cells, Kendall Cook, Katharine Tarnawsky, Alana J. Swinton, Daniel D. Yang, Alexandria S. Senetra, Gregory A. Caputo, Benjamin Carone, Timothy Vaden Jun 2019

Correlating Lipid Membrane Permeabilities Of Imidazolium Ionic Liquids With Their Cytotoxicities On Yeast, Bacterial, And Mammalian Cells, Kendall Cook, Katharine Tarnawsky, Alana J. Swinton, Daniel D. Yang, Alexandria S. Senetra, Gregory A. Caputo, Benjamin Carone, Timothy Vaden

College of Science & Mathematics Departmental Research

Alkyl-imidazolium chloride ionic liquids (ILs) have been broadly studied for biochemical and biomedical technologies. They can permeabilize lipid bilayer membranes and have cytotoxic effects, which makes them targets for drug delivery biomaterials. We assessed the lipid-membrane permeabilities of ILs with increasing alkyl chain lengths from ethyl to octyl groups on large unilamellar vesicles using a trapped-fluorophore fluorescence lifetime-based leakage experiment. Only the most hydrophobic IL, with the octyl chain, permeabilizes vesicles, and the concentration required for permeabilization corresponds to its critical micelle concentration. To correlate the model vesicle studies with biological cells, we quantified the IL permeabilities and cytotoxicities on …

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Equilibrium In The Catalytic Condensation Of Carboxylic Acids With Methyl Ketones To 1,3-Diketones And The Origin Of The Reketonization Effect, Alexey Ignatchenko, Thomas Diprospero, Heni Patel, Joseph R. Lapenna Jun 2019

Equilibrium In The Catalytic Condensation Of Carboxylic Acids With Methyl Ketones To 1,3-Diketones And The Origin Of The Reketonization Effect, Alexey Ignatchenko, Thomas Diprospero, Heni Patel, Joseph R. Lapenna

Chemistry Faculty/Staff Publications

Acetone is the expected ketone product of an acetic acid decarboxylative ketonization reaction with metal oxide catalysts used in the industrial production of ketones and for biofuel upgrade. Decarboxylative cross-ketonization of a mixture of acetic and isobutyric acids yields highly valued unsymmetrical methyl isopropyl ketone (MIPK) along with two less valuable symmetrical ketones, acetone and diisopropyl ketone (DIPK). We describe a side reaction of isobutyric acid with acetone yielding the cross-ketone MIPK with monoclinic zirconia and anatase titania catalysts in the absence of acetic acid. We call it a reketonization reaction because acetone is deconstructed and used for the construction …

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Organometallic Compounds As Carriers Of Extraterrestrial Cyanide In Primitive Meteorites, Karen E. Smith, Christopher H. House, Ricardo D. Arevalo Jr., Jason P. Dworkin, Michael P. Callahan Jun 2019

Organometallic Compounds As Carriers Of Extraterrestrial Cyanide In Primitive Meteorites, Karen E. Smith, Christopher H. House, Ricardo D. Arevalo Jr., Jason P. Dworkin, Michael P. Callahan

Chemistry and Biochemistry Faculty Publications and Presentations

Extraterrestrial delivery of cyanide may have been crucial for the origin of life on Earth since cyanide is involved in the abiotic synthesis of numerous organic compounds found in extant life; however, little is known about the abundance and species of cyanide present in meteorites. Here, we report cyanide abundance in a set of CM chondrites ranging from 50 ± 1 to 2472 ± 38 nmol·g−1, which relates to the degree of aqueous alteration of the meteorite and indicates that parent body processing influenced cyanide abundance. Analysis of the Lewis Cliff 85311 meteorite shows that its releasable cyanide …

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Extrapolating The Excitation Energy Of Polythiophene From Thiophene Oligomers, Jacob H. Wat, Graham Griffin Jun 2019

Extrapolating The Excitation Energy Of Polythiophene From Thiophene Oligomers, Jacob H. Wat, Graham Griffin

DePaul Discoveries

Organic semiconductors are used solar cells and as energy transferring materials. They can be separated into oligomers and polymers. In current computational studies oligomers are used to extrapolate the behavior of polymers. To do so many oligomers are created to extrapolate trends based on oligomer size. In this study a computer program was created to enable the quick and efficient production of oligomers ranging from 1 to 166 monomer units in length. The code was used to create thiophene oligomers. Through applying a linear fit, W. Khun fit and a polynomial fit excitation energy was predicted to be 2.001±0.002 eV, …

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Wavenumber-Dependent Complex Refractive Indices Of Synthetic Motor Oil By Aerosol Extinction Spectra, Daniel Olesak Jun 2019

Wavenumber-Dependent Complex Refractive Indices Of Synthetic Motor Oil By Aerosol Extinction Spectra, Daniel Olesak

DePaul Discoveries

Wavenumber-dependent, complex refractive indices, or optical constants, in the mid-infrared for unused Pennzoil 0W-20 motor oil have been obtained from aerosol extinction spectroscopy at room temperature. The oil’s spectroscopy is dominated by carbon-hydrogen stretching modes similar to those observed in spectra for pure alkanes. These same characteristic features were observed in a previously reported motor oil study. The optical constants retrieved here are an addition to the small number of data sets in the scientific literature for organic compounds many of which are components of aerosols present in the lower troposphere, particularly in urban areas. Such data offer new perspectives …

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Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter And Sulfur Dioxide From Vehicles And Brick Kilns And Their Impacts On Air Quality In The Kathmandu Valley, Nepal, Min Zhong, Eri Saikawa, Alexander Avramov, Chen Chen, Boya Sun, Wenlu Ye, William C. Keene, Robert J. Yokelson, Thilina Jayarathne, Elizabeth A. Stone, Maheswar Rupakheti, Arnico K. Panday Jun 2019

Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter And Sulfur Dioxide From Vehicles And Brick Kilns And Their Impacts On Air Quality In The Kathmandu Valley, Nepal, Min Zhong, Eri Saikawa, Alexander Avramov, Chen Chen, Boya Sun, Wenlu Ye, William C. Keene, Robert J. Yokelson, Thilina Jayarathne, Elizabeth A. Stone, Maheswar Rupakheti, Arnico K. Panday

Chemistry and Biochemistry Faculty Publications

Air pollution is one of the most pressing environmental issues in the Kathmandu Valley, where the capital city of Nepal is located. We estimated emissions from two of the major source types in the valley (vehicles and brick kilns) and analyzed the corresponding impacts on regional air quality. First, we estimated the on-road vehicle emissions in the valley using the International Vehicle Emissions (IVE) model with local emissions factors and the latest available data for vehicle registration. We also identified the locations of the brick kilns in the Kathmandu Valley and developed an emissions inventory for these kilns using emissions …

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The Development Of Individualized Anemia Treatments Using Point Of Care Diagnostics To Distinguish Anemia Caused By Infection Or Chronic Inflammation, Dr. Richard Watt Jun 2019

The Development Of Individualized Anemia Treatments Using Point Of Care Diagnostics To Distinguish Anemia Caused By Infection Or Chronic Inflammation, Dr. Richard Watt

Journal of Undergraduate Research

Background: Anemia that accompanies inflammation is associated with negative outcomes for patients. Early intervention to treat anemia is an important step in improving the quality of life for anemic patients. Our lab proposed to develop simple diagnostic tests using a Lateral Flow Immunoassays (LFIs) to measure the presence of a hormone called hepcidin because hepcidin is the master regulator of iron homeostasis in the body and elevated hepcidin levels lead to anemia.

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Rational Design Of Multifunctional Enzyme-Like Catalysts For Assembly-Line Chemical Synthesis, David Michaelis Jun 2019

Rational Design Of Multifunctional Enzyme-Like Catalysts For Assembly-Line Chemical Synthesis, David Michaelis

Journal of Undergraduate Research

The main objectives of this proposal was to publish our preliminary findings in peptide catalysis and then submit applications for external funding. Both of these objectives were accomplished during the grant period. In the Fall of 2017, we published our first paper on the development of our new enzyme-like catalysts (ACS Catal. 2017, 7, 7704–7708). This publication should serve as a springboard for additional publications in the area (on which we are currently working) and help ensure external funding for this project. During 2017-2018, we submitted 3 grant applications to the NIH to help support this project. These submissions have …

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Selective Isomer Formation And Crystallization-Directed Magnetic Behavior In Nitrogen-Confused C-Scorpionate Complexes Of Fe(O3Scf3)2, James R. Gardinier, Kristin J. Meise, Fathiya Jahan, Denan Wang, Sergey V. Lindeman Jun 2019

Selective Isomer Formation And Crystallization-Directed Magnetic Behavior In Nitrogen-Confused C-Scorpionate Complexes Of Fe(O3Scf3)2, James R. Gardinier, Kristin J. Meise, Fathiya Jahan, Denan Wang, Sergey V. Lindeman

Chemistry Faculty Research and Publications

The complex [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane, was prepared in order to compare its magnetic properties with those of the analogous parent complex, [Fe(HL)2](OTf)2, that lacks methyl groups on pyrazolyl rings and that undergoes spin crossover (SCO) from the low spin (LS) to the high spin (HS) form above room temperature. It was anticipated that this new semibulky derivative should favor the HS state and undergo SCO at a lower temperature range. During this study, six crystalline forms of 1 were prepared by …

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Comparison Between Hydrogen And Halogen Bonds In Complexes Of 6-Ox-Fulvene With Pnicogen And Chalcogen Electron Donors, Mingchang Hou, Qing-Zhong Li, Steve Scheiner Jun 2019

Comparison Between Hydrogen And Halogen Bonds In Complexes Of 6-Ox-Fulvene With Pnicogen And Chalcogen Electron Donors, Mingchang Hou, Qing-Zhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Quantum chemical calculations are applied to complexes of 6‐OX‐fulvene (X=H, Cl, Br, I) with ZH3/H2Y (Z=N, P, As, Sb; Y=O, S, Se, Te) to study the competition between the hydrogen bond and the halogen bond. The H‐bond weakens as the base atom grows in size and the associated negative electrostatic potential on the Lewis base atom diminishes. The pattern for the halogen bonds is more complicated. In most cases, the halogen bond is stronger for the heavier halogen atom, and pnicogen electron donors are more strongly bound than chalcogen. Halogen bonds to chalcogen atoms strengthen in the order O

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Additive-Free Palladium-Catalyzed Decarboxylative Cross-Coupling Of Aryl Chlorides, Ryan A. Daley, En Chih Liu, Joseph J. Topczewski Jun 2019

Additive-Free Palladium-Catalyzed Decarboxylative Cross-Coupling Of Aryl Chlorides, Ryan A. Daley, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

The cross-coupling of sodium (hetero)aryl carboxylates with (hetero)aryl chlorides proceed with 1 mol % palladium catalyst and does not require inorganic base, silver salts, or copper salts. This coupling uses two low energy partners, and the only stoichiometric byproducts are carbon dioxide and sodium chloride. The substrate scope includes less activated aryl chlorides and carboxylates (>25 examples). The palladium loading could be reduced to 0.1 mol %, and Buchwald-style precatalysts could be used.

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Triplet Population Dynamics And Excited State Relaxation In Chalcogenophene Polymers, Benjamin D. Datko Jun 2019

Triplet Population Dynamics And Excited State Relaxation In Chalcogenophene Polymers, Benjamin D. Datko

Chemistry and Chemical Biology ETDs

The conventional understanding of intersystem crossing in multichromophoric conju- gated polymers is usually depicted via a pure electronic model, neglecting contributions of vibrations or conformational order. Obtaining accurate structure-function correlations on spin-conversion processes involving photogenerated singlet excitons to triplet excitons and the excited state dynamics requires sensitivity to the subtle conformational ordering within conjugated polymers. This dissertation seeks to understand the kinetics of multi-exciton singlet-triplet interactions and the excited state relaxation of chalcogen containing (S, Se) conjugated polymers. Utilizing single molecule modulation spectroscopy allows determi- nation of triplet formation of individual conjugated polymer chains and aggregates. This technique resolves triplet-induced …

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Assay Of Vitamin B6 (Pyridoxine Hydrochloride) Utilizing Isocratic Reversed Phase High Performance Liquid Chromatography, Ronald Bartzatt, Purnima Gajmer, Mai Han Cassandra Nguyen, Alexndra My-Hanh Tran Jun 2019

Assay Of Vitamin B6 (Pyridoxine Hydrochloride) Utilizing Isocratic Reversed Phase High Performance Liquid Chromatography, Ronald Bartzatt, Purnima Gajmer, Mai Han Cassandra Nguyen, Alexndra My-Hanh Tran

Chemistry Faculty Publications

Aims: To demonstrate an analysis for vitamin B6 from commercial aqueous nutritional drinks and solid tablets, utilizing isocratic conditions with high performance liquid chromatography (HPLC) and UV detection at 290 nm. Study Design: Vitamin B6 in the form of pyridoxine hydrochloride is assayed by HPLC from various samples. Place and Duration of Study: Department of Chemistry, Durham Science Center, University of Nebraska, Omaha Nebraska from May to August 2016. Methodology: Utilizing a reversed-phase C-18 column with eluent solvent (19% ethanol, 77% water, 4% acetic acid), the samples were prepared in sample solvent (19% ethanol, 81% distilled water). Detection of vitamin …

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Modeling Main Group Metal Alkane Functionalization Reactions In Highly Acidic Carboxylic And Sulfuric Acid Solvents, Lily H. Carlson, Daniel H. Ess Jun 2019

Modeling Main Group Metal Alkane Functionalization Reactions In Highly Acidic Carboxylic And Sulfuric Acid Solvents, Lily H. Carlson, Daniel H. Ess

Journal of Undergraduate Research

Our group is interested in identifying the unknown mechanisms of main-group C-H functionalization reactions. In the long term, our goal is to use computational chemistry tools to develop general principles on mechanisms, intermediates, reactivity, and selectivity for hydrocarbon C-H functionalization reactions by p-block main-group compounds as well as provide prediction of new catalysts and reactions. However, in providing these predictions, it remains unclear if different mechanistic pathways and intermediates will be predicted if examined in a complete solvent sphere (see Figure 1 for technical details). This is especially important for non-aqueous solvents such as carboxylic acids and sulfuric acid. To …

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Heterodinuclear Co-Zr Compound Shows Increased Reactivity In Kumada Coupling, James Coombs, Daniel Ess Jun 2019

Heterodinuclear Co-Zr Compound Shows Increased Reactivity In Kumada Coupling, James Coombs, Daniel Ess

Journal of Undergraduate Research

Heterodinuclear compounds containing a metal–metal bond represent a potentially useful subclass of catalyst in organic synthesis. Heterodinuclear compounds offer the possibility of increased reactivity due to interactions between metal centers (Scheme 1A). These so-called cooperative effects can enhance reactivity by changing the electronic density, increasing nucleophilicity/electrophilicity of the reactive metal, and by lowering the energy barriers for changes in oxidation state. These changes in reactivity can allow a heterodinuclear compound to be an effective catalyst for many chemical reactions that would be unfeasible with a mononuclear analogue.

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Cyclic Peptide Catalyst Design, Millicent Campbell, David Michaelis Jun 2019

Cyclic Peptide Catalyst Design, Millicent Campbell, David Michaelis

Journal of Undergraduate Research

Enzymes found in nature are more efficient catalysts than those used in organic chemistry labs. However, natural enzymes are not ideal for organic synthesis because they only make one product and only work in specific conditions. The Michaelis lab designed a catalyst capable of mimicking enzyme-like reactivity in the lab. This catalyst consists of an alpha helix with an imidazolidinone catalyst and a thiourea catalyst (see figure 1). The imidazolidinone catalyst and thiourea catalysts are attached adjacent to each other on the alpha helix, which acts as a rigid scaffold that can mimic the proximity effects seen in natural enzymes. …

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In Vitro Evaluation Of Ovarian Cancer Tumorigenesis As A Function Of Quinone Oxidoreducatse-1 And Cell Phenotype, Milcah S. Jackson Jun 2019

In Vitro Evaluation Of Ovarian Cancer Tumorigenesis As A Function Of Quinone Oxidoreducatse-1 And Cell Phenotype, Milcah S. Jackson

LSU Doctoral Dissertations

In vitro multicellular spheroids are attractive model systems for assessing genetic and epigenetic changes that occur in diseased tissues. Understanding how such alterations in gene and subsequent protein expression affect disease progression and metastasis, drug resistance, and recurrence is of great interest in cancer research. In this regard, examining expression and activity of proteins, such as those with cytoprotective ability that are overexpressed in cancer cells, in addition to cell phenotype (i.e., stem-like, epithelial, mesenchymal, or mixed), are two ways to evaluate genetic and epigenetic changes. Moreover, determining the impact that cytoprotective proteins and cell phenotype have on tumor formation …

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