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Articles 1 - 10 of 10
Full-Text Articles in Chemistry
Carbohydrate Polymers As Controlled Release Devices For Pesticides, Soma Chakraborty, Maria Cleofe Neri-Badang
Carbohydrate Polymers As Controlled Release Devices For Pesticides, Soma Chakraborty, Maria Cleofe Neri-Badang
Chemistry Faculty Publications
Controlled release technology addresses problems associated with excessive use of toxic agricultural chemicals. This paper reviews the studies on the use of carbohydrate polymers as controlled release matrices for pesticides. Alginates, starch and its derivatives, chitosan, carboxymethylcellulose and ethylcellulose are some of the natural polymers discussed in this review. The advantages and disadvantages of these polymeric systems as well as the factors that affect pesticide release are presented. A discussion on the polymers’ encapsulation efficiency and release profile is also included, which will aid future researchers in identifying the suitable formulation for controlled release of pesticides. Combination of two polymers, …
Sintering-Induced Nucleation And Growth Of Noble Metal Nanoparticles For Plasmonic Resonance Ceramic Color, Nathan Dinh, Michael C. Leopold, Ryan Coppage
Sintering-Induced Nucleation And Growth Of Noble Metal Nanoparticles For Plasmonic Resonance Ceramic Color, Nathan Dinh, Michael C. Leopold, Ryan Coppage
Chemistry Faculty Publications
This study demonstrates the formation of nanoparticles (NPs) from metal salts within ceramic glazes, such that the use of this colorant technology is more accessible to artisans, employs less metal content, is less environmentally harmful, and allows for the use of traditional kilns. Gold NPs have been demonstrated to possess a specific, low material loading use as a ceramic glaze colorant via plasmon resonance. Pre-synthesized gold NPs that are added to ceramic glazes have been found to significantly change in size after firing in both reductive and oxidative atmospheres, but still maintain some size relationships and color properties. Unfortunately, it …
Polymers Course For Small Colleges And Universities, Joseph Furgal
Polymers Course For Small Colleges And Universities, Joseph Furgal
Chemistry Faculty Publications
This article describes the course design and teaching methodology for a polymer chemistry and applications lecture class specifically aimed at small college and university instruction. This intermediate course for advanced undergraduates and masters level graduate students focuses on teaching the basics of polymer history, synthesis and characterization with connections to the core chemistry curriculum in a small class size environment and without a textbook. Furthermore, an extensive overview of the applications of polymeric materials gives students a connection to real life applications. The course includes polymer case studies, informational lessons on real world objects made of polymers, and demonstrations. Student …
Regioselective Baeyer–Villiger Oxidation Of Lignin Model Compounds With Tin Beta Zeolite Catalyst And Hydrogen Peroxide, John Adam Jennings, Sean R. Parkin, Eric Munson, Sean Delaney, Julie L. Calahan, Mark Isaacs, Kunlun Hong, Mark Crocker
Regioselective Baeyer–Villiger Oxidation Of Lignin Model Compounds With Tin Beta Zeolite Catalyst And Hydrogen Peroxide, John Adam Jennings, Sean R. Parkin, Eric Munson, Sean Delaney, Julie L. Calahan, Mark Isaacs, Kunlun Hong, Mark Crocker
Chemistry Faculty Publications
Lignin depolymerization represents a promising approach to the sustainable production of aromatic molecules. One potential approach to the stepwise depolymerization of lignin involves oxidation of the benzylic alcohol group in β-O-4 and β-1 linkages, followed by Baeyer–Villiger oxidation (BVO) of the resulting ketones and subsequent ester hydrolysis. Towards this goal, BVO reactions were performed on 2-adamantanone, a series of acetophenone derivatives, and lignin model compounds using a tin beta zeolite/hydrogen peroxide biphasic system. XRD, 119Sn MAS NMR spectroscopy, DRUVS and XPS were used to determine tin speciation in the catalyst, the presence of both framework Sn and extra framework …
Relating Side Chain Organization Of Pnipam With Its Conformation In Aqueous Methanol, Debashish Mukherji, Manfred Wagner, Mark D. Watson, Svenja Winzen, Tiago E. E. De Oliveira, Carlos M. Marques, Kurt Kremer
Relating Side Chain Organization Of Pnipam With Its Conformation In Aqueous Methanol, Debashish Mukherji, Manfred Wagner, Mark D. Watson, Svenja Winzen, Tiago E. E. De Oliveira, Carlos M. Marques, Kurt Kremer
Chemistry Faculty Publications
Combining nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and μs long all-atom simulations with two million particles, we establish a delicate correlation between increased side chain organization of PNIPAm and its collapse in aqueous methanol mixtures. We find that the preferential binding of methanol with PNIPAm side chains, bridging distal monomers along the polymer backbone, results in increased organization. Furthermore, methanol–PNIPAm preferential binding is dominated by hydrogen bonding. Our findings reveal that the collapse of PNIPAm is dominated by enthalpic interactions and that the standard poor solvent (entropic) effects play no major role.
To Bend Or Not To Bend – Are Heteroatom Interactions Within Conjugated Molecules Effective In Dictating Conformation And Planarity?, Gary Conboy, Howard J. Spencer, Enrico Angioni, Alexander L. Kanibolotsky, Neil J. Findlay, Simon J. Coles, Claire Wilson, Mateusz B. Pitak, Chad Risko, Veaceslav Coropceanu, Jean-Luc Brédas, Peter J. Skabara
To Bend Or Not To Bend – Are Heteroatom Interactions Within Conjugated Molecules Effective In Dictating Conformation And Planarity?, Gary Conboy, Howard J. Spencer, Enrico Angioni, Alexander L. Kanibolotsky, Neil J. Findlay, Simon J. Coles, Claire Wilson, Mateusz B. Pitak, Chad Risko, Veaceslav Coropceanu, Jean-Luc Brédas, Peter J. Skabara
Chemistry Faculty Publications
We consider the roles of heteroatoms (mainly nitrogen, the halogens and the chalcogens) in dictating the conformation of linear conjugated molecules and polymers through non-covalent intramolecular interactions. Whilst hydrogen bonding is a competitive and sometimes more influential interaction, we provide unambiguous evidence that heteroatoms are able to determine the conformation of such materials with reasonable predictability.
Molecular Dynamics Study Of The Opening Mechanism For Dna Polymerase I, Carol A. Parish, Bill R. Miller Iii, Eugene Y. Wu
Molecular Dynamics Study Of The Opening Mechanism For Dna Polymerase I, Carol A. Parish, Bill R. Miller Iii, Eugene Y. Wu
Chemistry Faculty Publications
During DNA replication, DNA polymerases follow an induced fit mechanism in order to rapidly distinguish between correct and incorrect dNTP substrates. The dynamics of this process are crucial to the overall effectiveness of catalysis. Although Xray crystal structures of DNA polymerase I with substrate dNTPs have revealed key structural states along the catalytic pathway, solution fluorescence studies indicate that those key states are populated in the absence of substrate. Herein, we report the first atomistic simulations showing the conformational changes between the closed, open, and ajar conformations of DNA polymerase I in the binary (enzyme:DNA) state to better understand its …
Opacity Of P(Mma-Maa)-Pmma Composite Latex System With Varying Maa Concentration, Gilbert U. Yu, Jerry T. Dy, Erwin P. Enriquez
Opacity Of P(Mma-Maa)-Pmma Composite Latex System With Varying Maa Concentration, Gilbert U. Yu, Jerry T. Dy, Erwin P. Enriquez
Chemistry Faculty Publications
Polymer composites of core-shell morphology are commonly used in the paint industry as opacity enhancer. These are usually made of block copolymer systems wherein the core is formed from a polymer that swells in the presence of a solvent and surrounded by a high glass transition polymeric shell. Thus, upon drying, the swollen regions turn into voids while leaving a hard shell. Here, composites based on poly(methyl methacrylate-butyl acrylate) [P(MMA-BuA)] (seed stage), poly(methyl methacrylate-methacrylic acid) [P(MMA-MAA)] (second stage), and poly(methyl methacrylate) [PMMA] (third stage) were synthesized through a multistage sequential emulsion polymerization and their opacity was investigated. The second stage …
Stress-Induced Infrared Frequency Shifts In Polyethylene, George A. Pfeffer, Donald W. Noid
Stress-Induced Infrared Frequency Shifts In Polyethylene, George A. Pfeffer, Donald W. Noid
Chemistry Faculty Publications
The molecular dynamics technique is used to study the spectral response of a polyethylene chain in a crystal environment under a mechanical deformation. The MUSIC method, which was previously shown to accurately compute dispersion curves from the time-dependent structure factor, is used. A complete characterization of frequency shifts is presented for various lamellar thickness, temperatures, stress (or pressure), and mass defects.
Computer Simulation Of The Melting Process In Linear Macromolecules, Donald W. Noid, George A. Pfeffer, Stephen Z.D. Cheng, Bernhard Wunderlich
Computer Simulation Of The Melting Process In Linear Macromolecules, Donald W. Noid, George A. Pfeffer, Stephen Z.D. Cheng, Bernhard Wunderlich
Chemistry Faculty Publications
Polymer crystal melting kinetics is simulated by using molecular dynamics. A simplified molecular model of polyethylene crystal melting consisting of one extended chain on a polyethylene-like crystal surface is presented. The simulation data indicate that the end-to-end distance (eed) of radius of gyration (rg) has a simple exponential dependence on time. The rate constants for eed and rg are found to be temperature and molecular length dependent. A more detailed analysis of polymer crystal melting will be described.