Digital Commons Network^™

Remote Performance Modulation Of Ultrafiltration Membranes By Magnetically And Thermally Responsive Polymer Chains, Arijit Sengupta, Anh Vu, Xianghong Qian, Sumith R. Wickramasinghe

Chemical Engineering Faculty Publications and Presentations

Ultrafiltration membranes, that respond to an external magnetic field and local temperature have been developed. Surface-initiated activator-generated electron transfer (AGET) atom transfer radical polymerization (ATRP) has been used to graft poly(N-isopropylacrylamide) (PNIPAm) from the surface of 300 kDa regenerated cellulose membranes. The polymerization initiator was selectively attached to the entire membrane surface, only the outer membrane surface or only the inner pore surface. A superparamagnetic nanoparticle was attached to the end of the polymer chain. The DI water flux as well as the flux and rejection of bovine serum albumin were investigated in the absence and presence of a 20 …

Design And Synthesis Of Polymeric Metastable State Photoacid And Photo Co-Releasing Materials, Adnan Abdallah Muftah Elgattar

Theses and Dissertations

Metastable state photoacids (mPAHs) are molecules that possess a photoinduced metastable state with high acidity and good reversibility. The metastable state lasts long enough to produce a high proton concentration, which can drive various proton transfer processes. MPAHs have been intensively studied in recent years and applied to different chemical, material, biomedical areas. Covalently linking many mPAHs in a polymer allows the generation of a local proton concentration higher than that of the overall system. This dissertation described my PhD work on the synthesis of mPAH polymers using different radical and ring-opening polymerization methods. These polymers can repeatedly produce a …

The Aqueous Stability Of N-Acyl-L-Homoserine Lactones, Their Affinity For Cyclodextrin Inclusion, And The Investigation Of A Catalyst For Their Hydrolysis, Eric William Ziegler

Theses and Dissertations

Many bacteria demonstrate population-density dependent gene expression, a phenomenon known as quorum sensing, to regulate phenotypes that, if expressed by an individual bacterium, would be ineffective. While some of these phenotypes are innocuous (e.g., exhibiting bioluminescence), certain bacteria employ quorum sensing regulated phenotypes in their pathogenesis. Traditionally, infections by these pathogens have been treated with antibiotic therapies. However, with the emergence of multidrug resistant strains, alternative strategies are being considered for attenuation of quorum sensing regulated traits that do not apply selective pressures. Macrocycles — in particular the cyclodextrins — that are capable of forming inclusion complexes with Gram-negative quorum …

Synthesis Of Bulky And Polar Galactonoamidines For The Inhibition Of The Human Α-Galactosidase, Ifedi Orizu

Graduate Theses and Dissertations

Glycosidases are amongst the most abundant enzymes in nature. This is due to their role in the degradation of carbohydrates which are the major source of carbon or earth. The absence or malfunction of glycosidases is implicated in numerous diseases such as cancers, diabetes, and lysosomal storage disorders, which make them important drug targets for study in medicinal chemistry. The seminal work by Pauling and Wolfenden showed that enzymes bind to their substrate at the transition state with very strong affinity. Wolfenden estimated the dissociation constant to be around 10-22M. This encouraged the design of glycosidase inhibitors which mimicked one …

Electrochemical Oxidation Of Individual Silver Nanoparticles: Exploring The Effect Of Particle Shape, Capping Ligand, Electrolyte, And Potential On The Signal, Jazlynn Sikes

Graduate Theses and Dissertations

Nanomaterials have revolutionized science and technology. Their unique properties can be exploited, and nanoparticles are being used as catalysts, antimicrobials, drug delivery vehicles, sensors, and more. However, the fundamental properties of nanomaterials and their interactions with their surrounding environments are still poorly understood. In this work, a single-particle approach was used to observe the effects of capping ligand, surrounding solution, and particle shape on the oxidative process to gain deeper understanding of silver nanoparticle properties. When allowed the opportunity, the particles will adsorb to the electrode surface then oxidize in rapid succession upon electrode activation, regardless of capping ligand as …

Novel N-Derivatized-7-Nitroindolines For The Synthesis Of Photocleavable Crosslinkers, And For Solid Phase Peptide Synthesis, Hector Patricio Del Castillo

Open Access Theses & Dissertations

7-Nitroindoline-based photochemistry has focused mostly on N-acyl-7-nitroindolines, which have been used as photocleavable protecting groups for carboxylic acids that can be efficiently removed by illumination with UV-light. They offer an alternative to the more commonly used o-nitrobenzyl-based photocleavable protecting groups. N-acyl-7-nitroindolines can also be used as photochemical acylating agents in inert solvents. For example, they have found application in peptide fragment condensation, the convergent synThesis of N-glycopeptides, and the synThesis of peptide thioesters, forming amide and thioester bonds with amine and thiol nucleophiles, respectively, under neutral conditions. The photochemical activation of N-acyl-7-nitroindolines can occur with UV light (λ = 350 …

Organic Synthesis For Solving Clinical Conundrums Of Drug Activation And For Facilitating Natural Product Drug Discovery, Elkin Libardo Romero

Open Access Theses & Dissertations

Organic chemistry is an exploratory world in which chemists translate their knowledge by creating new molecules and explore their biological and physical properties. For the past three years, our research has been focused on organic synThesis and chemical biology to solve challenges in this area. Two major approaches have been faced: First, the chemical synThesis of the active metabolite of antithrombotic prodrug Plavix (clopidogrel). Clopidogrel (CPG) has been widely used as an antithrombotic prodrug, which undergoes extensive metabolism in patients; among it, only a trivial portion is converted through a series of cytochrome P450 (CYP)-catalyzed thiophene degradation to form active …

Stereochemical Control In Suzuki Cross Coupling Reactions Of Acyclic (Z)-Beta-Haloacroleins, William Carrick

Honors Theses

Beta-chloroenals are readily accessible substances and are efficient precursors for a variety of heterocyclic compounds. Suzuki type cross-coupling reactions of such compounds with arylboronic acids yield ��,��-diarylacroleins with control of stereochemistry. The oxidation of these enals to the corresponding acids and subsequent oxidative lactonization leads to formation of the respective coumarins. The chemistry involved in these transformations with special attention to stereochemistry of the Suzuki coupling reaction will be discussed. A full NMR analysis involving 1H, 13C, COSY, NOESY, HSQC, and HMBC was performed to unambiguously confirm the structure and show that the reaction proceeds with retention of stereochemistry.

Biomedical Applications And Syntheses Of Selected Anthraquinone Dyes, Richard Sirard

Senior Honors Theses

Anthraquinones are aromatic organic compounds that have multiple applications in the biomedical field. Some anthraquinone-based compounds are used as fluorophores to contrast cell nuclei while others act as chemotherapeutic agents. However, there are not many fluorescent anthraquinone cell stains currently available. In this study, commercially available anthraquinone dyes, in addition to other dye families and compounds, were reviewed for their unique properties, advantages, and drawbacks. The development and characterization of three novel anthraquinone fluorophores revealed promising photophysical characteristics, like large Stokes shifts. One of the compounds, RBS3, was chosen for fixed and live cell staining and exhibited desirable biomedical properties. …

Modeling The Problem Of Integral Geometry On A Family Of Hyperbolic And Spherical Curves, Azamat Pirimbetov, N. Uteuliev, G. Djaykov

Karakalpak Scientific Journal

The problems of integral geometry in a strip on a family of curves of hyperbolic and spherical type are considered which have numerous applications in problems of geophysics, thermoacoustic and photoacoustic tomography. Explicit formulas are obtained for the Fourier image of the solution of integral geometry problems in the class of smooth compactly supported functions. Further, the obtained formulas are investigated for stability using numerical methods. To solve the problems, algorithms are constructed. Numerical and graphical results of applying these algorithms to solving the problems are presented.

Application Of Atomically Precise Metal Nanoclusters In Electrocatalysis, Zhi-Hua Zhuang, Wei Chen

Journal of Electrochemistry

Metal nanoclusters (M NCs) consist of only several to a few hundred of metal atoms and possess core sizes less than 2 nm. Owing to the quantum size effect, the electronic states of M NCs evolve to discrete levels similar to the molecule energy gaps, other than a continuous density of states to produce plasmon characteristic of bulk metal nanoparticles (M NPs). In comparison with the conventional M NPs, M NCs exhibit dramatically unique electronic and optical properties, such as molecule-like energy gaps, strong photoluminescence and high catalytic properties, which make them promising for potential application in numerous fields, such …

Luminol/Sulfamic Acid Electrochemiluminescence And Its Application For Dopamine Detection, Tesfaye Hailemariam Barkae, Mohamed Ibrahim Halawa, Tadesse Haile Fereja, Shimeles Addisu Kitte, Xian-Gui Ma, Ye-Quan Chen, Guo-Bao Xu

Journal of Electrochemistry

Herein, sulfamic acid (SA) was utilized, for the first time, to enhance significantly the luminol electrochemiluminescence (ECL). With the SA concentration increased from 0.1 μmol·L^-1 to 500 μmol·L^-1 the ECL intensity increased proportionally. The developed luminol/SA ECL system was employed to detect dopamine (DA) based on its prominent quenching effect. The Stern-Volmer equation of I_o/I= 1+K_sv[DA] could be applied to express well the quenching mechanism of DA in the luminol/SA ECL system. The calibration plot showed that the increase in the DA concentration from 0.5 to 20 μmol·L^-1 decreased linearly the ECL intensity …

Theoretical Studies Of Metal-N-C For Oxygen Reduction And Hydrogen Evolution Reactions In Acid And Alkaline Solutions, Xue-Ping Qin, Shang-Qian Zhu, Lu-Lu Zhang, Shu-Hui Sun, Min-Hua Shao

Journal of Electrochemistry

Single atom catalysts (SAC) have been regarded as the promising alternatives to platinum group metals due to their low costs and potentially high catalytic activities in various electrocatalytic reactions. The atomic mechanism understanding of activity discrepancy among different metal and nitrogen co-doped carbon-based catalysts is still lacking. Here, non-precious metal and nitrogen co-doped carbons (Me-N-C, Me = Fe and Co) as the model catalysts are investigated by combining experimental and theoretical studies to explore the catalytic activities and corresponding reaction mechanisms toward oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) at universal pHs. Atomic theoretical simulations suggest that Fe-N-C …

Preparation And Characterization Of "Water-In-Salt" Polymer Electrolyte For Lithium-Ion Batteries, Xu Hou, Xin He, Jie Li

Journal of Electrochemistry

Since the development of wearable and flexible electronic products, the demand of flexible energy storage devices such as batteries and super capacitors is in urgent. To enhance the safety and cycling stability for flexible lithium-ion batteries, “water-in-salt” polymer electrolyte was prepared by introducing 21 mol·kg^-1 LiTFSI electrolyte into cross-linked polyacrylamide (PAM) after freeze-drying. A great amount of holes with the size range of 10 ~ 20 μm can be found on the surface and in the bulk of polyacrylamide, which is benefited from the freeze-drying process and acts as a great support for the electrolyte uptake. The “water-in-salt” polymer …

Surface Functionalization Of Elastomers For Tunable Crystal Growth And Smart Adhesives, John Kapitan

Department of Chemistry: Dissertations, Theses, and Student Research

Silicone rubbers have seen extensive work on modulation of their surface environments for use in microfluidics, cell adhesion, and sensing. Most surface procedures utilize a common initial step of oxidation of the surface to increase the number of active surface functional groups. Following oxidation more permanent functionalities can be imparted on the surface using silanization, grafting polymer brushes, or creating ionic bonds to the surface. Of these three, silanization proves to be the most pervasive due to the range of procedures available and how easy the procedures prove to be. However, the mechanism by which silanization is performed heavily involves …

The Interconnectivity Of Parkinson's Disease And Type Two Diabetes Mellitus, Erica Olfson

Honors Scholars Collaborative Projects

This thesis is about the biochemical connection between Parkinson's disease and Type II Diabetes Mellitus.

Co-Evolutionary Analysis Suggests A Role For Tlr9 In Papillomavirus Restriction, Kelly King, Brendan B. Larsen, Sophie Gryseeis, Cécile Richet, Simona Kraberger, Robert Jackson, Michael Worobey, Joseph S. Harrison, Arvind Varsani, Koenraad Van Doorslaer

College of the Pacific Faculty Articles

Upon infection, DNA viruses can be sensed by pattern recognition receptors (PRRs) leading to the activation of type I and III interferons, aimed at blocking infection. Therefore, viruses must inhibit these signaling pathways, avoid being detected, or both. Papillomavirus virions are trafficked from early endosomes to the Golgi apparatus and wait for the onset of mitosis to complete nuclear entry. This unique subcellular trafficking strategy avoids detection by cytoplasmic PRRs, a property that may contribute to establishment of infection. However, as the capsid uncoats within acidic endosomal compartments, the viral DNA may be exposed to detection by toll-like receptor (TLR) …

Studies Of The Rectification Behavior Of The Pdt Ligand And The Active Site Of Msrp, Laura J. Ingersol

Chemistry and Chemical Biology ETDs

Molybdenum (Mo) is an essential element that plays an important role in global nitrogen, carbon, and sulfur cycles with a critical role in human metabolism and ecological balance. It becomes catalytically active when complexed with the pyranopterin dithiolene ligand (PDT), forming the nearly ubiquitous molybdenum cofactor (Moco). The complex biosynthetic pathway of Moco, its presence in all three domains of life, and its role as a constituent cofactor in the last universal common ancestor (LUCA) all point toward the importance of the PDT in the development of life on Earth. Molybdoenzymes catalyze the two-electron oxidation or reduction of substrates that …

Inhibiting Nitroso Related Methylation Of Guanine Using Dietary Supplements And Flavonoids, Madeline Mccoy, James Davis, Chloe Rippey, Stephen Hobson

Liberty University Research Week

Undergraduate

Basic

Raising Global Awareness And Internationality In The Undergraduate Organic Chemistry Laboratory, Marissa Scilley, Michael R. Korn

Liberty University Research Week

Undergraduate

Applied

Engineering Donor-Acceptor Conjugated Polymers For High-Performance And Fast-Response Organic Electrochemical Transistors, Hanyu Jia, Zhen Huang, Peiyun Li, Song Zhang, Yunfei Wang, Jie Yu Wang, Xiaodan Gu, Ting Lei

Faculty Publications

To date, high-performance organic electrochemical transistors (OECTs) have mostly been based on polythiophene systems. Donor–acceptor (D–A) conjugated polymers are expected to be promising materials for OECTs owing to their high mobility and comparatively low crystallinity (good for ion diffusion). However, the OECT performance of D–A polymers lags far behind that of the polythiophenes. Here we synergistically engineered the backbone and side chain of a series of diketopyrrolopyrrole (DPP)-based D–A polymers and found that redox potential, molecular weight, solution processability, and film microstructures all have a severe impact on their performance. After systematic engineering, P(bgDPP-MeOT2) exhibited the best figure-of-merit (μC …

A Novel Molecular And Cellular Study On Curcumin, Khang Nguyen

Undergraduate Research Conference

Since the discovery of G-quartet (G4)by M. Gellertin 1962, much attention has been given on G4and C4(also called i-motif) as important drug design targets for the treatment of various human disorders. G4 forming sequences are prevalent in human genome, which includes many important regions of the eukaryotic genome, such as telomere ends, regulatory regions of many oncogenes c-kit, proto-oncogene c-myc, Kirsten rat sarcoma viral oncogene homolog (KRas). Curcumin(diferuloylmethane), an antiinflammatory and antioxidant compound, is found in the rhizomes of the plant Curcuma longa. The phytopolyphenolic chemical curcumin has been in the prominence due to its diverse pharmacological activities. Here, we …

Biotransformation Of Hbe And Other Benzofuran Derivatives, Hannah Trauger

Undergraduate Research Conference

No abstract provided.

Deletion Of Ph Response Genes In Cryptococcus Neoformans, Hannah Finson, Michael S. Price

Liberty University Research Week

Undergraduate

Basic

Greening Of Ferrocene Column Chromatography, Marissa Scilley, Anderson Hill, Michael R. Korn

Liberty University Research Week

Undergraduate

Basic

Design And Analysis Of A Novel Fluorescent Cell Stain, Simeon Standridge, Richard Sirard, Michael R. Korn

Liberty University Research Week

Undergraduate

Basic

Synthesis Of Some Rhenium-Pyridazyl Complexes For Future Use In Semiconductive Materials, Zachariah Hutcheon, Jonathan Nelson, Philip Temple, Mark Villers, Chad Snyder

Liberty University Research Week

Undergraduate

Basic

A Spectroscopic And Computational Study Of Diacetyl And Water Clusters, Margaret Baldwin

Honors Theses

Diacetyl, otherwise known as 1,2-butadione or biacetyl, is a flavor additive used in microwave popcorn, and more importantly as of late, e-cigarettes. The compound is known to cause lung disease for those who have been exposed to a large quantity of the buttery smelling molecule. As such, the characterization of diacetyl’s vibrational modes when it interacts with water are pivotal to understanding the effects it has on human lung tissue. In this research, the intermolecular interactions between water and diacetyl and the effects they have on one another’s vibrational modes are explored. While some experimental data is presented, the spectra …

Squaramide Structure And Interactions With Benzene, Serina Tressler

Undergraduate Research and Scholarship Symposium

The chemical industry’s continued reliance on expensive and toxic metal catalysts has driven the search for greener and more sustainable alternatives. One such option is hydrogen bonding organocatalysts, a group of inexpensive compounds made from renewable feedstocks. However, the interactions of these compounds with aryl groups is not currently understood, limiting their overall effectiveness. Dual hydrogen bond donors such as squaramide and thiourea have been a focus of study for some time, but the structure and interactions of unsubstituted squaramide have not been thoroughly reported and present an unknown in catalyst design. This study seeks to understand the structure of …

Development Of A Rapid Drug Detection Method For Insects Using Paper Spray Ionization Mass Spectrometry (Psi-Ms), Alexandria Plyler

Undergraduate Research and Scholarship Symposium

Insects have the ability to reflect the chemical environment that they have developed in. Thus, necrogenous insects can reflect the chemical environment of cadavers they have fed on. Forensic scientists can potentially utilize insect larvae as an alternate biological matrix to detect drugs in cadavers that are skeletonized, burned, or otherwise badly damaged. Analysis of insects using paper spray ionization mass spectrometry (PSI-MS), an analytical method requiring little to no sample preparation, could prove a rapid, cost-effective, and non-destructive alternative form of toxicological analysis. Traditional tissue analysis via GC and LC-MS often require lengthy sample preparation, use expensive reagents, and …