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Articles 1231 - 1260 of 33132

Full-Text Articles in Chemistry

Synthesis Of Novel Five-Membered Heterocycles As Bioactive Agents, Subrata Roy Apr 2025

Synthesis Of Novel Five-Membered Heterocycles As Bioactive Agents, Subrata Roy

Student Theses and Dissertations

This dissertation outlines the synthesis of various types of heterocyclic small molecules across three chapters. The first chapter discusses the efficient synthesis of seventy-one fluorinated pyrazole molecules and thirty-five 3,4-dihydroxy and 4-hydroxy phenyl-substituted thiazole molecules. These molecules were designed and synthesized for their potential antibacterial properties. The second chapter discusses the synthesis of fused thiazole molecules with enone-based steroidal natural products. This chapter reports on sixty-five novel fused thiazole molecules distributed across three libraries featuring different steroidal natural products: ethisterone, bisnoralcohol, and diosgenin. These molecules were designed and synthesized as potential anticancer agents. The third chapter comprises the development of …


Rewiring An Enzyme: K135f Mutation In Malate Dehydrogenase, Lauren Ratz, Kaci Schmoll Apr 2025

Rewiring An Enzyme: K135f Mutation In Malate Dehydrogenase, Lauren Ratz, Kaci Schmoll

Undergraduate Research Symposium 2025

Malate Dehydrogenase (MDH) is an enzyme that catalyzes the reaction of malate to oxaloacetate by reducing the cofactor NAD+ to NADH in the citric acid cycle, playing a crucial role in cellular metabolism. Alterations in the MDH structure have been linked to metabolic diseases and cancers, though its overall structure remains poorly characterized. To better understand MDH, we manipulated its structure by inserting a point mutation into the flexible loop region at position 135, exchanging a lysine (Lys) to a phenylalanine (Phe). We hypothesized that mutating a positively charged amino acid (Lys) to an aromatic amino acid (Phe) would cause …


Antioxidant Properties Of Phytochemicals In Watercress And Mint Extracts In Serum Albumin, Perla Tovar Apr 2025

Antioxidant Properties Of Phytochemicals In Watercress And Mint Extracts In Serum Albumin, Perla Tovar

Undergraduate Research Conference

Hypothesis: Phytochemicals present in mint and watercress help stabilize protein under oxidative stress. Main Objective: Analyze the interaction of HSA with different phytochemicals present in mint extract.


Preservation And Integrity Of Laboratory Solutions: Understanding The Impact Of Storage Practices On Chemical Stability And Experimental Accuracy, Azza Al Jahdhami Apr 2025

Preservation And Integrity Of Laboratory Solutions: Understanding The Impact Of Storage Practices On Chemical Stability And Experimental Accuracy, Azza Al Jahdhami

Honors Theses

Chemical storage methods represent a key matter ignored within labs, educational sites, workplaces, and even households. Many people, including various students and instructors within the chemistry field, are unaware of the proper methods for storing and disposing of common chemicals. This study aims to understand the effects of storage practices on chemical stability and experimental accuracy, dealing with the following questions: What kind of effects result from improper chemical disposal? How can improper storage affect the overall chemical effectiveness? Why is sink disposal of many solutions discouraged, and why is waste container disposal always necessary?

Through a literature review, this …


Ai-Based Detection Of Optical Microscopic Images Of Pseudomonas Aeruginosa In Planktonic And Biofilm States, Bidisha Roy Sengupta, Esther Mallet, Angel Torres, Ravyn Solis Apr 2025

Ai-Based Detection Of Optical Microscopic Images Of Pseudomonas Aeruginosa In Planktonic And Biofilm States, Bidisha Roy Sengupta, Esther Mallet, Angel Torres, Ravyn Solis

Faculty Publications

No abstract provided.


Systematic Characterization Of The Homogeneous And Heterogeneous Hydrogen Halide Dimers, Yuan Xue, Gregory S. Tschumper Apr 2025

Systematic Characterization Of The Homogeneous And Heterogeneous Hydrogen Halide Dimers, Yuan Xue, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

This study systematically characterizes the four homogeneous and six heterogeneous hydrogen-bonded dimers formed by hydrogen halide pairs (HX/HY where X, Y = F, Cl, Br, and I). The notation HX⋯HY indicates the direction of the hydrogen bond from the HY donor to the HX acceptor. All stationary points reported for these ten dimer systems are fully optimized utilizing the MP2 and CCSD(T) ab initio methods in conjunction with quadruple-ζ correlation-consistent basis sets augmented with diffuse functions, and their nature is verified by harmonic vibrational frequency computations. The electronic dissociation energies (De) for all ten global minima are evaluated near the …


The Delocalized Toolbox: Tuning Strain, Energetic And Optoelectronic Properties Of Aryl Heterocyclic Scaffolds For Application-Driven Endeavors, Michael Josef Holzmann Apr 2025

The Delocalized Toolbox: Tuning Strain, Energetic And Optoelectronic Properties Of Aryl Heterocyclic Scaffolds For Application-Driven Endeavors, Michael Josef Holzmann

Chemistry and Chemical Biology ETDs

This is a three-part dissertation. Part 1 is composed of chapters 1-3 which revolves around the optimization of cyclononyne reactivity towards 1,3 dipolar cycloadditions. Specifically, the synthesis and reactivity of sulfate, sulfamate and sulfamide-bearing cyclononynes will be discussed. Chapters 4-5 comprise Part 2 which addresses optimization of ruthenium olefin metathesis towards reversible activation and inhibition. The mechanism of reversible inhibition mediated by a hexaarylbiimidazole photo-inhibitor will be elucidated. Part 3 consists of chapters 6-8 which describes structure-functional relationship studies on carbon dots and harnessing that insight for sensing applications. Data relating to assays performed with explosive analytes will be analyzed …


Detection And Quantitation Of Drugs And Pesticides In Food Products Of The Uae (Dates And Camel Milk) By Liquid Chromatographic Techniques, Afnan W. Alanqar Apr 2025

Detection And Quantitation Of Drugs And Pesticides In Food Products Of The Uae (Dates And Camel Milk) By Liquid Chromatographic Techniques, Afnan W. Alanqar

Thesis/ Dissertation Defenses

In this thesis the detection and quantification of the traces of multi-residue pesticides in 26 dates samples as well as the presence of the anthelmintic drug thiabendazole in pasteurized commercial milk consumed in the United Arab Emirates is examined. The main objective of this thesis is two folds. First is to determine whether a selected group of 12 pesticides of 8 different groups- in the case of dates- and the drug thiabendazole-in case of camel milk- exists in the randomly collected samples of corresponding matrices. Second, is to quantify these compounds and compare their amount to the established maximum residue …


To Bee Or Not To Bee: Investigating Pesticide Behavior Inside And Outside Semi-Field Cages, Mallory Bingham Apr 2025

To Bee Or Not To Bee: Investigating Pesticide Behavior Inside And Outside Semi-Field Cages, Mallory Bingham

Student Research Symposium

Background

Pesticides are vital in preventing crop damage from pests but are cited as a key factor in decreasing bee populations.1 The alfalfa leaf cutting bee is essential in alfalfa seed production in the Western US.2 Current research seeks to examine the effects of pesticides on these solitary bees to maintain healthy populations while controlling pests.3

One research tool commonly used to examine pesticide effects on bees is field-cages. Field cages are thought to simulate agroecosystem conditions while restricting bees to plots that have been sprayed with pesticides.1,4

However, environmental conditions can be different inside and …


Expressing And Purifying Homologs Of Crispr Systems, Gabe Parrish Apr 2025

Expressing And Purifying Homologs Of Crispr Systems, Gabe Parrish

Student Research Symposium

CRISPR (Clustered Regularly Interspaced Palindromic Repeat)-Cas (CRISPR- associated) is a protein-nucleic acid adaptive immune system in Bacterial and Archaeal organisms that defends against invading foreign genetic material.


Solving The Structure Of An Ancestral Protein Tyrosine Phosphatase, Natalie Turcsanski, Edna Armah Apr 2025

Solving The Structure Of An Ancestral Protein Tyrosine Phosphatase, Natalie Turcsanski, Edna Armah

Student Research Symposium

Protein tyrosine phosphatases (PTPs) regulate cell signaling by removing phosphate groups from tyrosine residues. Malfunction of these enzymes can lead to diseases such as diabetes and cancer. A conserved feature among PTPs is the catalytic acid loop, essential for phosphate removal. Computational analysis of PTP structures revealed that ancestral PTPs have considerable variation in conformations of this loop, sparking interest in their further study. The Asgard group, identified as ancestral to eukaryotic PTPs, was successfully expressed and purified under optimized conditions. Current efforts focus on optimizing crystallization to obtain larger crystals for structural analysis. This project will investigate the allosteric …


Determining The Function Of Type Iv-B Crispr-Cas Systems, Eric Jenkins, Brendon Guinn Apr 2025

Determining The Function Of Type Iv-B Crispr-Cas Systems, Eric Jenkins, Brendon Guinn

Student Research Symposium

CRISPR-Cas systems are a diverse group of prokaryotic adaptive immune systems that defend against Mobile Genetic Elements (MGEs) such as bacteriophages and plasmids. CRISPR-associated (Cas) proteins bind to guide RNAs (crRNAs) transcribed from a DNA repeat array (CRISPR array) containing spacers complementary to MGEs. Upon infection by a MGE, the Cas protein-crRNA complex binds to the target sequence in the invaders genome and cleaves the nucleic acid.


Sensitive Fluorescence Quantitation And Efficient Free Radical Characterization Of N‑Glycans Via Lc-Flr-Hrms/Ms With A Novel Fluorescent Free Radical Tag, Rayan Murtada, C. J. Szafranski, Maria Tevletidis, Shane Finn, Wilthon Gilles, Tabia Tahsin, Jinshan Gao Apr 2025

Sensitive Fluorescence Quantitation And Efficient Free Radical Characterization Of N‑Glycans Via Lc-Flr-Hrms/Ms With A Novel Fluorescent Free Radical Tag, Rayan Murtada, C. J. Szafranski, Maria Tevletidis, Shane Finn, Wilthon Gilles, Tabia Tahsin, Jinshan Gao

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Glycans are some of the most difficult biomolecules to analyze owing to their branching tendencies as well as their regiochemical and stereochemical diversity. Yet, the correlation between various pathological states and glycan quantity or structural alterations has demonstrated the importance and urgency for the development of a more robust glycan analytical technique. Furthermore, the manufacturing and regulation of biopharmaceuticals demands a feasible and improved analytical approach toward the characterization and quantitation of glycosylations. Unfortunately, multiple commercially available glycan tags lack, in combination, liquid chromatography detection sensitivity, chemical stability and, most importantly, optimal glycan characterization capabilities. Therefore, a novel fluorescent tag …


Detection Of Co2 Locally Generated By Formate Dehydrogenase Using Carbonate Ion-Selective Micropipette Electrodes, Seol Baek, Salvador Gutierrez-Portocarrero, Rokas Gerulskis, Shelley D. Minteer, Sean R. German, Henry S. White Apr 2025

Detection Of Co2 Locally Generated By Formate Dehydrogenase Using Carbonate Ion-Selective Micropipette Electrodes, Seol Baek, Salvador Gutierrez-Portocarrero, Rokas Gerulskis, Shelley D. Minteer, Sean R. German, Henry S. White

Chemistry Faculty Research & Creative Works

Many technologies involve immobilizing catalysts such as enzymes on surfaces, and the catalytic activities or functional efficiencies of these surface-bound catalysts can vary depending on orientations, localized binding sites, active sites, and intrinsic molecular nature. Accurate and rapid quantification of reaction products from surface-immobilized catalysts is crucial for understanding the selectivity, mechanisms, and reaction dynamics of catalytic systems and for revealing heterogeneous catalytic activities and reaction sites for applications such as biosensors and energy conversion/generation systems. Here, we demonstrate the feasibility of localized enzymatic activity measurements using microscale carbon dioxide (CO2)-sensitive ion-selective electrode (ISE) pipettes (0.5-2.5 μm tip …


Predicting PkA Of Flexible Polybasic Tetra-Aza Macrocycles, Tatum K. Harvey, Kristof Pota, Magy Mekhail, David M. Freire, Donatus A. Agbaglo, Benjamin G. Janesko, Kayla N. Green Apr 2025

Predicting PkA Of Flexible Polybasic Tetra-Aza Macrocycles, Tatum K. Harvey, Kristof Pota, Magy Mekhail, David M. Freire, Donatus A. Agbaglo, Benjamin G. Janesko, Kayla N. Green

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We present physics-based pKa predictions for a library of tetra-aza macrocycles. These flexible, polybasic molecules exhibit highly charged states and substantial prototropic tautomerism, presenting a challenge for pKa prediction. Our computational protocol combines CREST/xTB conformational sampling, density functional theory (DFT) refinement in continuum solvent, and a linear empirical correction (LEC). This approach predicts known tetra-aza macrocycle pKa to within a root-mean-square deviation 1.2 log units. This approach also provides reasonable predictions for the most stable protomers at different pH. We use this protocol to predict pKa values for four novel, synthetically achievable, …


Living With Alzheimer’S: A Guide To How To Lower The Risk Of Memory Loss & Care For Those With Alzheimer’S, Mona Muzammil, Washain Muzammil Apr 2025

Living With Alzheimer’S: A Guide To How To Lower The Risk Of Memory Loss & Care For Those With Alzheimer’S, Mona Muzammil, Washain Muzammil

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

Despite the frequent characterization of Alzheimer's disease as a “loss of self,"" this enlightening book demonstrates unequivocally that a person's unique self persists throughout the course of the disease. The important message in Caring for People with Alzheimer’s is how much can be done in care settings to support a person's sense of identity and thereby enrich the lives of people experiencing the many losses associated with dementia. Drawing from a diverse body of research, this book brings together the recommendations of the best thinkers and practitioners in multiple disciplines to illustrate the meaning of self and the importance of …


Seasonal Effects Of Plant Functional Groups On Molecular Biogeochemistry Of Dissolved Organic Matter In Porewater Of A Poor Fen, Zhimin Song, Maryam Khaksari, Erik A. Lilleskov, Evan Kane, Paul V. Doskey Apr 2025

Seasonal Effects Of Plant Functional Groups On Molecular Biogeochemistry Of Dissolved Organic Matter In Porewater Of A Poor Fen, Zhimin Song, Maryam Khaksari, Erik A. Lilleskov, Evan Kane, Paul V. Doskey

Michigan Tech Publications

Climate change may transform peatlands from net carbon (C) sinks to C sources, which could result in a positive feedback to global warming. Warmer temperatures might lower water tables, increase the abundance of shrubs, slow Sphagnum and sedge growth and further accelerate the decomposition of dissolved organic matter (DOM) with a concomitant release of C from the surface. Studies in which vascular plant functional groups (PFGs) in peatlands have been manipulated to mimic the potential effects of a warming climate on DOM are scarce. In the subject study, seasonal effects of PFGs on the molecular composition of DOM of peat …


Highly Regenerable Magnetic Sulfonated Chitosan Crosslinked With Glutaraldehyde Composite Beads (Iron Sand/Naso3-Chi-G) For Aqueous Mercury Removal, Fathurrahmi Fathurrahmi, Rahmi Rahmi, Lelifajri Lelifajri, Anggun Sixthia Wulan Ayu, Muhammad Iqhrammullah Apr 2025

Highly Regenerable Magnetic Sulfonated Chitosan Crosslinked With Glutaraldehyde Composite Beads (Iron Sand/Naso3-Chi-G) For Aqueous Mercury Removal, Fathurrahmi Fathurrahmi, Rahmi Rahmi, Lelifajri Lelifajri, Anggun Sixthia Wulan Ayu, Muhammad Iqhrammullah

Karbala International Journal of Modern Science

We developed a novel adsorbent from sulfonated, glutaraldehyde-crosslinked chitosan embedded with magnetic iron sand. The adsorbent was synthesized through a two-step process: (1) sulfonation with N(SO₃Na)₃ to introduce sulfonate groups, and (2) crosslinking with glutaraldehyde to enhance structural stability. The optimal formulation, containing 43.5% iron sand and crosslinked with 0.17 M glutaraldehyde, exhibited the highest Hg²⁺ adsorption capacity (30.74 mg/g) at pH 3. The adsorbents were characterized using Scanning Electron Microscopy (SEM), Fourier transform infra-red spectroscopic (FT-IR), and X-ray diffraction (XRD) techniques. Adsorption equilibrium was achieved within 60 minutes, and isotherm modeling showed that the process followed the Freundlich model …


Antioxidant Activity Of Pamam Dendrimer Stabilized Ascorbic Acid, Gabriella Srikureja Apr 2025

Antioxidant Activity Of Pamam Dendrimer Stabilized Ascorbic Acid, Gabriella Srikureja

Honors Theses

Ascorbic acid (vitamin C) is an essential micronutrient for human health. It acts as an enzymatic cofactor in anabolic biochemical pathways such as the synthesis of collagen, dopamine, and norepinephrine. Unfortunately, this versatility comes at the cost of a high degradation rate both in and outside of the food matrix. Previous research exploring stabilizing aqueous ascorbic acid through Poly(amidoamine) (PAMAM) dendrimers found success in reducing the rate of degradation.

To confirm the antioxidant activity of ascorbic acid in its stabilized dendrimer complex, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assays examined via Cary 5000 UV-Vis-NIR spectrophotometer found that performing the DPPH assay under aqueous conditions …


Transition Metal Nanocomposites: Nonenzymatic Biosensor For Neurochemical Detection, Amitav Sen, Ace Cannon, Manashi Nath Apr 2025

Transition Metal Nanocomposites: Nonenzymatic Biosensor For Neurochemical Detection, Amitav Sen, Ace Cannon, Manashi Nath

Miners Solving for Tomorrow Research Conference

No abstract provided.


Additive Manufacturing Of Thermoplastic Composites, Matik Heskin, K. Chandrashekhara, Richard Billo, Ming-Chuan Leu, Thomas P. Schuman Apr 2025

Additive Manufacturing Of Thermoplastic Composites, Matik Heskin, K. Chandrashekhara, Richard Billo, Ming-Chuan Leu, Thomas P. Schuman

Miners Solving for Tomorrow Research Conference

No abstract provided.


Polymerization Methods For Vinyl Phosphonate Monomers: Challenges And Perspectives, Sara Mccauley Apr 2025

Polymerization Methods For Vinyl Phosphonate Monomers: Challenges And Perspectives, Sara Mccauley

Miners Solving for Tomorrow Research Conference

No abstract provided.


An Open-Framework Iron-Selenite As Cathode For Li- Ion Batteries, Sutapa Bhattacharya, Aleksandr V. Chernatynskiy, Amitava Choudhury Apr 2025

An Open-Framework Iron-Selenite As Cathode For Li- Ion Batteries, Sutapa Bhattacharya, Aleksandr V. Chernatynskiy, Amitava Choudhury

Miners Solving for Tomorrow Research Conference

No abstract provided.


Maldi-Mass Spectrometry Imaging To Investigate Distribution Of Per- And Polyfluoroalkyl Substances In Exposed Poplar Tissues, Tonglin Zhou, Varuni Abhayarayne, Joseph Akor, Honglan Shi, Paul Ki-Souk Nam, Joel Gerard Burken, John Yang Apr 2025

Maldi-Mass Spectrometry Imaging To Investigate Distribution Of Per- And Polyfluoroalkyl Substances In Exposed Poplar Tissues, Tonglin Zhou, Varuni Abhayarayne, Joseph Akor, Honglan Shi, Paul Ki-Souk Nam, Joel Gerard Burken, John Yang

Miners Solving for Tomorrow Research Conference

No abstract provided.


Preliminary Assessment Of Non-Volatile Particulate Matter And Gaseous Emissions From A Premixed Pre-Vaporized Combustor Designed For Civil Supersonic Transport, Ugochukwu Ewuzie, Godwin Ifeanyi Ogbuehi, Steven Achterberg, Monday Uchenna Okoronkwo, Philip D. Whitefield Apr 2025

Preliminary Assessment Of Non-Volatile Particulate Matter And Gaseous Emissions From A Premixed Pre-Vaporized Combustor Designed For Civil Supersonic Transport, Ugochukwu Ewuzie, Godwin Ifeanyi Ogbuehi, Steven Achterberg, Monday Uchenna Okoronkwo, Philip D. Whitefield

Miners Solving for Tomorrow Research Conference

No abstract provided.


The Effect Of Nanomorphology As Quantified Via The K‑Index On The Drug Delivery Properties Of Isocyanate-Derived Aerogels, Stephen Y. Owusu, A. B. M. Shaheen Ud Doulah, Vaibhav A. Edlabadkar, Kamden J. George, Chariklia Sotiriou-Leventis Apr 2025

The Effect Of Nanomorphology As Quantified Via The K‑Index On The Drug Delivery Properties Of Isocyanate-Derived Aerogels, Stephen Y. Owusu, A. B. M. Shaheen Ud Doulah, Vaibhav A. Edlabadkar, Kamden J. George, Chariklia Sotiriou-Leventis

Miners Solving for Tomorrow Research Conference

No abstract provided.


Relationships Between High-Elevation Lake Water Chemistry And Soil Chemistry, Christopher Houdeshell, Rachel Hovel Apr 2025

Relationships Between High-Elevation Lake Water Chemistry And Soil Chemistry, Christopher Houdeshell, Rachel Hovel

Student Scholarship

Past atmospheric deposition of sulfuric and nitric acids (“acid rain”) has acidified high elevation lakes across Maine and New England, affecting the ecology of the lakes and their surroundings. Since the passage of the Clean Air Act Amendments in 1990, acid deposition has declined and many of the affected lakes have begun to recover. However, this recovery trajectory does not look the same at all lakes. Across western Maine, nine high-elevation lakes have been part of long-term water chemistry monitoring since 1986 and show variation in their pH trends over time, with five of the lakes increasing in pH, three …


Heteroleptic Self-Assembly Of Platinum Metallocycles Based On Naphthalene-Diimide And Aromatic Dicarboxylate, Erendra Manandhar Apr 2025

Heteroleptic Self-Assembly Of Platinum Metallocycles Based On Naphthalene-Diimide And Aromatic Dicarboxylate, Erendra Manandhar

Presentations - 2025

A core-substituted naphthalene-diimide, functionalized with pyridinyl phenyl and octyl groups, was synthesized via Suzuki coupling and self-assembled with Pt(II) and Pd(II) phosphane triflates. The resulting triangular metallocycle structures were characterized by various methods, showing solvent-dependent UV-Vis absorption and fluorescence, and self-assembled into nanostructures.


Exploring Rotational Energy Transfer Of Intermolecular Collisions In Complex Systems: A Mqct Approach, Carolin Anna Joy Apr 2025

Exploring Rotational Energy Transfer Of Intermolecular Collisions In Complex Systems: A Mqct Approach, Carolin Anna Joy

Dissertations (1934 -)

The accurate modeling of molecular spectra in astrophysical environments requires detailed understanding of collisional energy transfer processes, which remains a significant challenge due to the computational complexity of quantum mechanical calculations for larger molecules, heavier projectiles, and higher collision energies. This dissertation addresses this challenge through the development and application of Mixed Quantum/Classical Theory (MQCT), a hybrid approach that combines quantum mechanical treatment of internal molecular motion with classical description of translational degrees of freedom. The methodology was first validated through detailed study of rotational energy transfer in the ND3 + D2 system, demonstrating excellent agreement with full quantum results …


Exploring 7-Bbh As An Alternative To 9-Bbn, Katelyn P. Griffin Apr 2025

Exploring 7-Bbh As An Alternative To 9-Bbn, Katelyn P. Griffin

ASPIRE 2025

9-BBN is an important compound in the synthesis of terminal alcohols by providing high regioselectivity for the anti-Markovnikov position. It is also used as a reducing agent for ketones and aldehydes and various alkyl ligation reactions. The processes involved in its synthesis and 9-BBN’s relative low solubility in most solvents renders it expensive and difficult to transport. We have made 2-isopropyl-5-methyl-7-borabicyclo[2.2.1]heptane (7-BBH) from relatively inexpensive precursor γ-terpinene and borane dimethyl sulfide complex. Characterization data and preliminary results from the use of 7-BBH for hydroboration and reduction will be discussed.