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Physical Sciences and Mathematics Commons™

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Chemistry

Series

The University of Southern Mississippi

2007

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Rheology Of Tin Fluorophosphate Glass/Polyamide 12 Hybrids In The Low Concentration Regime, Kevin Urman, Thomas Schweizer, Joshua U. Otaigbe Nov 2007

Rheology Of Tin Fluorophosphate Glass/Polyamide 12 Hybrids In The Low Concentration Regime, Kevin Urman, Thomas Schweizer, Joshua U. Otaigbe

Faculty Publications

Phosphate glass (Pglass)/polymer hybrids are a unique material class that promises to help fulfill the growing need for new advanced materials. Rheological investigations into Pglass/polyamide 12 hybrids have shown a strong dependence on temperature and composition. Strong negative deviations from the log-additivity rule are also observed for these materials as well as a reduction in the activation energy for viscous flow. Hybrids containing < 2 vol. % Pglass are theologically simple fluids that display temperature independence in plots of storage modulus versus loss modulus. Hybrids containing >= 2 vol. % Pglass are rheologically complex and do not obey the time-temperature superposition principle. Through application of Han plots, we identified a structural change that occurs in hybrids containing >= 2 vol. % Pglass at …

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Instrumentation And Metrology For Single Rna Counting In Biological Complexes Or Nanoparticles By A Single-Molecule Dual-View System, Hui Zhang, Dan Shu, Faqing Huang, Peixuan Guo Oct 2007

Instrumentation And Metrology For Single Rna Counting In Biological Complexes Or Nanoparticles By A Single-Molecule Dual-View System, Hui Zhang, Dan Shu, Faqing Huang, Peixuan Guo

Faculty Publications

Limited by the spatial resolution of optical microscopy, direct detection or counting of single components in biological complexes or nanoparticles is challenging, especially for RNA, which is conformationally versatile and structurally flexible. We report here the assembly of a customized single-molecule dual-viewing total internal reflection fluorescence imaging system for direct counting of RNA building blocks. The RNA molecules were labeled with a single fluorophore by in vitro transcription in the presence of a fluorescent AMP. Precise calculation of identical or mixed pRNA building blocks of one, two, three, or six copies within the bacteriophage phi29 DNA packaging motor or other …

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Snell's Law Of Refraction Observed In Thermal Frontal Polymerization, John A. Pojman, Veronika Viner, Burcu Binici, Shanna Lavergne, Melanie Winsper, Dmitry Golovaty, Laura Gross Sep 2007

Snell's Law Of Refraction Observed In Thermal Frontal Polymerization, John A. Pojman, Veronika Viner, Burcu Binici, Shanna Lavergne, Melanie Winsper, Dmitry Golovaty, Laura Gross

Faculty Publications

We demonstrate that Snell’s law of refraction can be applied to thermal fronts propagating through a boundary between regions that support distinct frontal velocities. We use the free-radical frontal polymerization of a triacrylate with clay filler that allows for two domains containing two different concentrations of a peroxide initiator to be molded together. Because the polymerization reaction rates depend on the initiator concentration, the propagation speed is different in each domain. We study fronts propagating in two parallel strips in which the incident angle is 90°. Our data fit Snell’s law vr/vi = sin θr/sin …

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Synthesis, Characterization, And Cyclopolymerization Of A Functional Non-Symmetric Divinyl Monomer, Bekir Dizman, Lon J. Mathias Aug 2007

Synthesis, Characterization, And Cyclopolymerization Of A Functional Non-Symmetric Divinyl Monomer, Bekir Dizman, Lon J. Mathias

Faculty Publications

A non-symmetric divinyl monomer with terminal carboxylic acid functionality was readily synthesized from the reaction of ethyl α-hydroxymethylacrylate (EHMA) with maleic anhydride. The new monomer (EHMA–MA) was homopolymerized in both bulk and ethyl acetate using AIBN as an initiator to give cyclopolymers. The synthesis of the monomer and cyclopolymers were followed by 13C NMR, 1H NMR, and FTIR. 1H NMR was also utilized to obtain the degree of cyclization of the polymers, which were found to be 95% or higher in all cases. The molecular weights of the cyclopolymers were around 40–60,000 g/mol as estimated by SEC. …

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Structural Analysis Of Csos1a And The Protein Shell Of The Halothiobacillus Neapolitanus Carboxysome, Yingssu Tsai, Michael R. Sawaya, Gordon C. Cannon, Fei Cai, Eric B. Williams, Sabine Heinhorst, Cheryl A. Kerfeld, Todd O. Yeates Jun 2007

Structural Analysis Of Csos1a And The Protein Shell Of The Halothiobacillus Neapolitanus Carboxysome, Yingssu Tsai, Michael R. Sawaya, Gordon C. Cannon, Fei Cai, Eric B. Williams, Sabine Heinhorst, Cheryl A. Kerfeld, Todd O. Yeates

Faculty Publications

The carboxysome is a bacterial organelle that functions to enhance the efficiency of CO2 fixation by encapsulating the enzymes ribulose bisphosphate carboxylase/ oxygenase (RuBisCO) and carbonic anhydrase. The outer shell of the carboxysome is reminiscent of a viral capsid, being constructed from many copies of a few small proteins. Here we describe the structure of the shell protein CsoS1A from the chemoautotrophic bacterium Halothiobacillus neapolitanus. The CsoS1A protein forms hexameric units that pack tightly together to form a molecular layer, which is perforated by narrow pores. Sulfate ions, soaked into crystals of CsoS1A, are observed in the pores of the …

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Accumulation Of Pathological Tau Species And Memory Loss In A Conditional Model Of Tauopathy, Zdenek Berger, Hanno Roder, Amanda Hanna, Vijayaraghavan Rangachari, Mei Yue, Zbigniew Wszolek, Karen Ashe, Joshua Knight, Dennis Dickson, Cathy Andorfer, Terrone L. Rosenberry, Jada Lewis, Mike Hutton, Christopher Janus Apr 2007

Accumulation Of Pathological Tau Species And Memory Loss In A Conditional Model Of Tauopathy, Zdenek Berger, Hanno Roder, Amanda Hanna, Vijayaraghavan Rangachari, Mei Yue, Zbigniew Wszolek, Karen Ashe, Joshua Knight, Dennis Dickson, Cathy Andorfer, Terrone L. Rosenberry, Jada Lewis, Mike Hutton, Christopher Janus

Faculty Publications

Neurofibrillary tangles (NFTs) are a pathological hallmark of Alzheimer's disease and other tauopathies, but recent studies in a conditional mouse model of tauopathy (rTg4510) have suggested that NFT formation can be dissociated from memory loss and neurodegeneration. This suggests that NFTs are not the major neurotoxic tau species, at least during the early stages of pathogenesis. To identify other neurotoxic tau protein species, we performed biochemical analyses on brain tissues from the rTg4510 mouse model and then correlated the levels of these tau proteins with memory loss. We describe the identification and characterization of two forms of tau multimers (140 …

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Antibacterial Fluoromicas: A Novel Delivery Medium, Bekir Dizman, Jonathan C. Badger, Mohamed O. Elasri, Lon J. Mathias Jan 2007

Antibacterial Fluoromicas: A Novel Delivery Medium, Bekir Dizman, Jonathan C. Badger, Mohamed O. Elasri, Lon J. Mathias

Faculty Publications

Antibacterial fluoromicas were prepared by ion-exchanging fluoromicas with different antibacterial agents including various quaternary ammonium compounds, AgNO3, and norfloxacin. Antibacterial activities of the ion-exchanged fluoromicas were determined against Staphylococcus aureus and Escherichia coli. Minimum inhibitory concentration (MIC) and zone of inhibition (ZOI) tests were performed to determine both antibacterial effectiveness and mode of action associated with the fluoromicas. All treated fluoromicas showed excellent antibacterial activities against both types of bacteria. The antibacterial activities of treated fluoromicas were found to be either better than or the same as those of neat antibacterial agents. The repeated antibacterial activity tests demonstrated …

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