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Articles 13051 - 13080 of 15540
Full-Text Articles in Entire DC Network
A Study Of Rheological And Thermodynamic Properties Of Polymer-Clay Gels And Multilayered Films, Eduard Adrian Stefanescu
A Study Of Rheological And Thermodynamic Properties Of Polymer-Clay Gels And Multilayered Films, Eduard Adrian Stefanescu
LSU Doctoral Dissertations
The overall objective of the research presented here is to understand the nanoscopic and microscopic structures that exist in dispersions of laponite and montmorillonite in poly(ethylene oxide), (PEO) and to correlate their shear responses with the final structure and properties of multilayered nanocomposite films prepared from these dispersions. These structures were examined as a function of polymer molecular weight, polymer and clay concentrations, and type of clay used to prepare the nanocomposites. A sequence of shear and elongational rheological measurements is used to provide a more complete physical picture on the structure of polymer-clay hydrogels, while a combination of techniques …
The Synthesis Of Water Soluble N-Acyl Chitosan Derivatives For Characterization As Antibacterial Agents, Lakia Monique Champagne
The Synthesis Of Water Soluble N-Acyl Chitosan Derivatives For Characterization As Antibacterial Agents, Lakia Monique Champagne
LSU Doctoral Dissertations
Currently, natural polysaccharides are being utilized increasingly in the markets because they exhibit biodegradability, biocompatibility, versatility, and are found abundant in nature. The diversity of natural polysaccharides provides the chemist with a broad spectrum of raw materials that can be used in many biological applications. Chitosan is a natural polysaccharide that possesses excellent biological properties. It has been recognized for its antibacterial activity, in that it is destructive towards the bacterium Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antibacterial property of chitosan can be enhanced by changing the hydrophobic/hydrophilic nature of the polysaccharide backbone. This research entails …
Lignin Degradation In Wood-Feeding Insects, Scott M. Geib, Timothy R. Filley, Patrick G. Hatcher, Kelli Hoover, John E. Carlson, Maria Del Mar Jimenez-Gasco, Akiko Nakagawa-Izumi, Rachel L. Sleighter, Ming Tien
Lignin Degradation In Wood-Feeding Insects, Scott M. Geib, Timothy R. Filley, Patrick G. Hatcher, Kelli Hoover, John E. Carlson, Maria Del Mar Jimenez-Gasco, Akiko Nakagawa-Izumi, Rachel L. Sleighter, Ming Tien
Chemistry & Biochemistry Faculty Publications
The aromatic polymer lignin protects plants from most forms of microbial attack. Despite the fact that a significant fraction of all lignocellulose degraded passes through arthropod guts, the fate of lignin in these systems is not known. Using tetramethylammonium hydroxide thermochemolysis, we show lignin degradation by two insect species, the Asian longhorned beetle (Anoplophora glabripennis) and the Pacific dampwood termite (Zootermopsis angusticollis). In both the beetle and termite, significant levels of propyl side-chain oxidation (depolymerization) and demethylation of ring methoxyl groups is detected; for the termite, ring hydroxylation is also observed. In addition, culture-independent fungal gut …
Synthesis And Evaluation Of Vegetable (Soybean) Oil Based Epoxy Resin For Beverage Can Coating And Enzymatic Synthesis And Characterization Of Tailored N&C End Protected Oligopeptides, Ying Gao
Doctoral Dissertations
"Research described in this dissertation covers two topics. Part-I is related to the development of a soybean oil based epoxy resin and its application in beverage can coatings. Interior surfaces of beverage can are invariably coated with polymer coating. The most commonly used coatings at present are derived from bisphenol A (BPA) based epoxy reins. However, due to perceived endocrine disrupting nature of BPA and consequential adverse effects on humans and wildlife concerns for the use of BPA based coatings and its leaching into beverages have been expressed. The research in the first part describes the synthesis and evaluation of …
Size-Controlled Synthesis Of Monodisperse Core/Shell Nanogels, William H. Blackburn, L. Andrew Lyon
Size-Controlled Synthesis Of Monodisperse Core/Shell Nanogels, William H. Blackburn, L. Andrew Lyon
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Small, monodisperse nanogels (similar to 50-nm radius) were synthesized by free-radical precipitation polymerization and were characterized using a suite of light scattering and chromatography methods. Nanogels were synthesized with either N-isopropylacrylamide or N-isopropylmethacrylamide as the main monomer, with acrylic acid or 4-acrylamidofluorescein as a comonomer and N,N'-methylenebis(acrylamide) as a cross-linker. By varying the surfactant and initiator concentrations, particle size was controlled while maintaining excellent monodispersity. An amine-containing shell was added to these core particles to facilitate subsequent bioconjugation. Successful conjugation of folic acid to the particles was demonstrated as an example of how such materials might be employed in a …
Characterization Of Microorganisms Of Interest To Homeland Security And Public Health Utilizing Liquid Chromatography/Mass Spectrometry, Robert A. Everley
Characterization Of Microorganisms Of Interest To Homeland Security And Public Health Utilizing Liquid Chromatography/Mass Spectrometry, Robert A. Everley
Theses and Dissertations
Liquid chromatography/quadrupole time of flight mass spectrometry (LC/QTOF MS) utilizing electrospray ionization was employed to monitor protein expression in Escherichia coli and Shigella organisms. Automated charge state deconvolution, spectral subtraction and spectral mirroring were used to reveal subtle differences in the LC/MS data. Reproducible intact protein biomarkers were discovered based on their unique mass, retention time and relative intensity. These markers were implemented to differentiate closely related strain types, (e.g. two distinct isolates of E. coli O157:H7) and to correctly identify unknown pathogens. Notable, was the distinction of multiple serotypes of enterohaemorrhagic E. coli which cannot be distinguished by clinical …
Reduced Acute Inflammatory Responses To Microgel Conformal Coatings, Amanda W. Bridges, Neetu Singh, Kellie L. Burns, Julia E. Babensee, L. Andrew Lyon, Andrés J. García
Reduced Acute Inflammatory Responses To Microgel Conformal Coatings, Amanda W. Bridges, Neetu Singh, Kellie L. Burns, Julia E. Babensee, L. Andrew Lyon, Andrés J. García
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Implantation of synthetic materials into the body elicits inflammatory host responses that limit medical device integration and biological performance. This inflammatory cascade involves protein adsorption, leukocyte recruitment and activation, cytokine release, and fibrous encapsulation of the implant. We present a coating strategy based on thin films of poly(N-isopropylacrylamide) hydrogel microparticles (i.e. microgels) cross-linked with poly(ethylene glycol) diacrylate. These particles were grafted onto a clinically relevant polymeric material to generate conformal coatings that significantly reduced in vitro fibrinogen adsorption and primary human monocyte/macrophage adhesion and spreading. These microgel coatings also reduced leukocyte adhesion and expression of pro-inflammatory cytokines (TNF-alpha, IL-1 beta, …
Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman
Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Dimethylsulfide (DMS) atmospheric and oceanic concentrations and eddy covariance air/sea fluxes were measured over the N. Atlantic Ocean during July 2007 from Iceland to Woods Hole, MA, USA. Seawater DMS levels north of 55 degrees N ranged from 3 to 17 nM, with variability related to the satellite-derived distributions of coccoliths and to a lesser extent, chlorophyll. For the most intense bloom region southwest of Iceland, DMS air/sea fluxes were as high as 300 mu mol m(-2) d(-1), larger than current model estimates. The observations imply that gas exchange coefficients in this region are significantly greater than those estimated using …
Synthesis And Properties Of New Polyamides Based On 4-Phenylenediacrylic Acid And Hydantoin Derivatives In The Main Chain, Khalil Faghihi
Synthesis And Properties Of New Polyamides Based On 4-Phenylenediacrylic Acid And Hydantoin Derivatives In The Main Chain, Khalil Faghihi
Turkish Journal of Chemistry
Six new polyamides (5a-f) containing p-phenylenediacrylic and hydantoin moieties in the main chain were prepared by direct polycondensation reaction of 4-phenylenediacrylic acid (3) with 6 different hydantoin derivatives (4a-f) using thionyl chloride and pyridine as condensing agents and N-methyl-2-pyrolidone as solvent. These new polymers (5a-f) were obtained in high yield and inherent viscosity between 0.35-0.55 dL/g. The resulting polyamides were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, and FT-IR and UV-vis spectroscopy. 4-Phenylenediacrylic acid (3) was prepared by the reaction of terephthal aldehyde (1) with malonic acid (2) in the presence of pyridine.
Synthesis, Spectroscopic And Biological Investigation Of Cyclic Octapeptide: Cherimolacyclopeptide G, Rajiv Dahiya
Synthesis, Spectroscopic And Biological Investigation Of Cyclic Octapeptide: Cherimolacyclopeptide G, Rajiv Dahiya
Turkish Journal of Chemistry
A natural cyclic octapeptide cherimolacyclopeptide G (8) was synthesized by coupling of tetrapeptide units Boc-Gly-Ala-Val-Pro-OMe (5) and Boc-Ile-Tyr-Ala-Pro-OMe (6) after proper deprotection at carboxyl and amino terminals followed by cyclization of the linear peptide segment. The structure was elucidated by IR, ^1H-NMR, ^{13}C-NMR, FAB MS spectral data, and elemental analyses. The newly synthesized cyclopeptide was also evaluated for its antimicrobial, anthelmintic, and cytotoxic activities and found to exhibit potent anthelmintic and cytotoxic activity against earthworms, Megascoplex konkanensis, Pontoscotex corethruses, and Eudrilus species, and Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines. In addition, compound 8 possessed moderate …
Oxidative Cyclisation Of 3-Oxopropanenitriles Mediated Manganese(Iii) Acetate With 2-Thienyl Substituted Alkenes, Mehmet Yilmaz, Neşe Uzunali̇oğlu, Mehtap Yakut, A. Tarik Pekel
Oxidative Cyclisation Of 3-Oxopropanenitriles Mediated Manganese(Iii) Acetate With 2-Thienyl Substituted Alkenes, Mehmet Yilmaz, Neşe Uzunali̇oğlu, Mehtap Yakut, A. Tarik Pekel
Turkish Journal of Chemistry
The oxidative cyclisation of 3-oxopropanenitriles 1a-g with alkenes 2a-c containing 2-thienyl group by manganese(III) acetate was studied. Treatment of 3-oxopropanenitriles 1a-d with 2-[(E)-2-phenylvinyl] thiophene 2a gave 4-phenyl-5-(2-thienyl)-4,5-dihydrofuran-3-carbonitriles 3a-d in moderate yields (52%-60%). 5-(2-thienyl) substituted 4,5-dihydrofuran-3-carbonitriles 3e-i were obtained by the oxidative cyclisation of these 3-oxopropanenitriles with 2-[(E)-1-methyl-2- phenylvinyl]thiophene 2b in good yields (54%-68%). In addition, the reactions of 2-(1-phenylvinyl)thiophene 2c with various 3-oxopropanenitriles produced 4,5-dihydrofurans 3j-n containing heterocycle in 77%-91% yields.
One-Step Synthesis Of Hyaluronic Acid-Based (Sub)Micron Hydrogel Particles: Process Optimization And Preliminary Characterization, Nurettin Sahiner, Xinqiao Jia
One-Step Synthesis Of Hyaluronic Acid-Based (Sub)Micron Hydrogel Particles: Process Optimization And Preliminary Characterization, Nurettin Sahiner, Xinqiao Jia
Turkish Journal of Chemistry
Hyaluronic acid (HA)-based (sub)micron hydrogel particles were synthesized by crosslinking virgin HA with divinyl sulfone (DVS) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelle systems under basic conditions. Experimental parameters including HA molecular weight, solution concentration, and reaction time were systematically varied in order to obtain well defined hydrogel particles. The use of a cosurfactant, 1-heptanol (1-HP), had a profound effect on the reaction kinetics and the particle morphology. The resulting particles exhibit negative charges on their surfaces. In vitro biocompatibility study indicates that these particles do not cause severe death to the cultured fibroblasts. These HA-based hydrogel particles are promising candidates …
Biologically Active Transition Metal Chelates With A 2-Thiophenecarboxaldehyde-Derived Schiff Base: Synthesis, Characterization, And Antibacterial Properties, Cezar Spinu, Maria Pleniceanu, Cristian Tigae
Biologically Active Transition Metal Chelates With A 2-Thiophenecarboxaldehyde-Derived Schiff Base: Synthesis, Characterization, And Antibacterial Properties, Cezar Spinu, Maria Pleniceanu, Cristian Tigae
Turkish Journal of Chemistry
Metal complexes, ML_2Cl_2, where M is Fe(II), Co(II), Ni(II), Cu(II), Zn(II), or Cd(II), and L is the Schiff base formed by condensation of 2-thiophenecarboxaldehyde with 2-aminopyridine, N-(2-thienylmethylidene)-2-aminopyridine (TNAPY) have been prepared and characterized by elemental analysis, and magnetic and spectroscopic measurements. Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal-ligand). Infrared and NMR spectra of the complexes agree with the coordination to the central metal atom through the nitrogen of the azomethine (-HC=N-) group and the sulfur atom of the thiophene ring. Magnetic susceptibility data coupled with electronic and ESR spectra suggest a distorted octahedral structure for the …
Interaction Of Mefenamic Acid With Cobalt(Ii) Ions In Aqueous Media: Evaluation Via Classic And Response Surface Methods, Mohammad Edrissi, Nima Razzaghi Asl, Behrooz Madjidi
Interaction Of Mefenamic Acid With Cobalt(Ii) Ions In Aqueous Media: Evaluation Via Classic And Response Surface Methods, Mohammad Edrissi, Nima Razzaghi Asl, Behrooz Madjidi
Turkish Journal of Chemistry
Mefenamic acid reacts with cobalt(II) ions in aqueous alkaline medium to form a highly stable deep brown complex at ambient temperature. The complexation process was optimized in terms of pH, temperature, agitation rate, and contact time using classical studies. A response surface method based on Box-Behnken design was used to statistically model the complexation reaction and investigate factor effects along with their interactions. A quadratic model was developed using experimental data with a correlation coefficient of 0.9609. Numerical optimization was performed to achieve the optimum solutions of factor combinations. The results of the classical investigation and statistical method were in …
Thermal Decomposition Of Metal Complexes Of Type Mlx_2 (M = Co(Ii), Cu(Ii), Zn(Ii), And Cd(Ii); L = Die; X = No_3^{1-}) By Tg-Dta-Dtg Techniques In Air Atmosphere, Muhammad Arshad, Saeed Ur-Rehman, Ammad Hussain Qureshi, Khalid Masud, Muhammad Arif, Aamer Saeed, Riaz Ahmed
Thermal Decomposition Of Metal Complexes Of Type Mlx_2 (M = Co(Ii), Cu(Ii), Zn(Ii), And Cd(Ii); L = Die; X = No_3^{1-}) By Tg-Dta-Dtg Techniques In Air Atmosphere, Muhammad Arshad, Saeed Ur-Rehman, Ammad Hussain Qureshi, Khalid Masud, Muhammad Arif, Aamer Saeed, Riaz Ahmed
Turkish Journal of Chemistry
The nitrate complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula M(DIE)(NO_3)_2, where M = Co(II), Cu(II), Zn(II), and Cd(II), were synthesized. The compositions of metal complexes and ligand were investigated by elemental analysis in order to ensure their purity and the structure elucidations were based on conductivity measurements, room temperature magnetic moment studies, proton NMR, and electronic and IR spectra. The thermal behavior of these complexes possessing distorted tetrahedral geometry and their ligand was studied by means of thermoanalytical techniques in static air atmosphere in order to determine their mode of decomposition and thermal stability. All these …
The Synthesis And Antimicrobial Activity Of \\\\Gamma-Butyrolactone Derivatives, Slobodan Sukdolak, Slavica Solujic-Sukdolak, Nenad Vukovic, Tanja Milosevic
The Synthesis And Antimicrobial Activity Of \\\\Gamma-Butyrolactone Derivatives, Slobodan Sukdolak, Slavica Solujic-Sukdolak, Nenad Vukovic, Tanja Milosevic
Turkish Journal of Chemistry
This paper examines the synthesis of \gamma-butyrolactone compounds 2, 3, 4, 5, and 9, and their potential antimicrobial nature and ability. The structures of all the compounds mentioned above were determined and confirmed with elemental analyses, and IR, ^1H-NMR, and ^{13}C-NMR spectroscopy. The in vitro antimicrobial activity of compounds 2, 3, 4, 5, and 9 was examined and evaluated against the following pathogens: Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Aspergillus niger, and Candida albicans. Compound 5 (20 mg/mL) demonstrated high antimicrobial activity against S. epidermidis, which was closely comparable to the antimicrobial …
Production Of (S)-(-)-1-(1´-Napthyl) Ethanol By Rhodotorula Glutinis Isolate Using Ram Horn Peptone, Esabi̇ Başaran Kurbanoğlu, Kani̇ Zi̇lbeyaz, Namudar I. Kurbanoğlu, Mesut Taşkin, Hamdullah Kiliç
Production Of (S)-(-)-1-(1´-Napthyl) Ethanol By Rhodotorula Glutinis Isolate Using Ram Horn Peptone, Esabi̇ Başaran Kurbanoğlu, Kani̇ Zi̇lbeyaz, Namudar I. Kurbanoğlu, Mesut Taşkin, Hamdullah Kiliç
Turkish Journal of Chemistry
The bioreduction of 1-acetonaphthone 1 by locally isolated Rhodotorula glutinis strains using ram horn peptone (RHP) gave (S)-(-)-1-(1´-naphthyl) ethanol (2), an important pharmaceutical intermediate. R. glutinis strains were isolated from the water of fermented Salix leaves. Optimum fermentation conditions for the production of 2 were 200 rpm, 32 °C, and pH 6.5. The production of 2 with excellent enantiomeric excess (>99%), and good conversion (100%) and yield (78%) under optimum conditions was achieved up to preparative scale via a fermenter. Wide temperature, pH, time, and agitation ranges did not affect the enantiomeric excess (ee) of the bioreduction product. A …
Examination Of The Electroanalytic Performance Of Carbon Nanotube (Cnt) Modified Carbon Paste Electrodes As Xanthine Biosensor Transducers, Ülkü Anik, Meli̇ha Çubukçu
Examination Of The Electroanalytic Performance Of Carbon Nanotube (Cnt) Modified Carbon Paste Electrodes As Xanthine Biosensor Transducers, Ülkü Anik, Meli̇ha Çubukçu
Turkish Journal of Chemistry
The effect of multi-walled carbon nanotube (MWCNT) and single-wall carbon nanotube (SWCNT) on carbon paste electrode (CPE) electrochemical response was examined by introducing various portions of CNT into the CPE. The optimum electrode structure was determined by comparing the prepared electrodes´ electroanalytical performance towards ferricyanide. Then these optimum compositions were modified with xanthine oxidase (XO) enzyme for obtaining a xanthine biosensor. After the optimization of biosensor working conditions, the developed systems were characterized for xanthine. Linearity was obtained in the concentration range between 1 and 100 \mu M xanthine with an RSD value of 3.35% for MWCNT-CPE, while with SWCNT-CPE …
Synthesis And Cloning Of A Small Bacillus Pheromone Gene (Comx_{Ro-B-2}) By Primer-Dimer Formation With Pcr, Devri̇m Demi̇r Dora, Tanil Kocagöz, Fi̇li̇z Öner
Synthesis And Cloning Of A Small Bacillus Pheromone Gene (Comx_{Ro-B-2}) By Primer-Dimer Formation With Pcr, Devri̇m Demi̇r Dora, Tanil Kocagöz, Fi̇li̇z Öner
Turkish Journal of Chemistry
ComX pheromone is the major extracellular signaling peptide stimulating transformation in response to high cell density in Bacillus species. In this study, Bacillus mojavensis ComX_{(RO-B-2)} pheromone gene was cloned to pGEMT-Easy vector based on TA cloning of PCR products. The gene encoding 11 amino acid peptides of Bacillus mojavensis RO-B-2 strain ComX pheromone (GLQIYTNWVPS) was obtained by PCR amplification of 2 primers complementary to each other at their 3' end. This eliminated the need for the original bacterial gene as DNA template for PCR. The amplified PCR products were ligated directly without any modification by T4 DNA ligase into pGEMT-Easy …
Preparation, Characterization, And Potentiometric Titrations Of Some New Di-[3-(3-Alkyl/Aryl-4,5-Dihydro-1h-1,2,4-Triazol-5-One-4-Yl)-Azomethinphenyl] Isophthalate/Terephthalate Derivatives, Haydar Yüksek, Özlem Gürsoy Kol
Preparation, Characterization, And Potentiometric Titrations Of Some New Di-[3-(3-Alkyl/Aryl-4,5-Dihydro-1h-1,2,4-Triazol-5-One-4-Yl)-Azomethinphenyl] Isophthalate/Terephthalate Derivatives, Haydar Yüksek, Özlem Gürsoy Kol
Turkish Journal of Chemistry
3-Alkyl(Aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with di-(3-formylphenyl) isophthalate (3) and di-(3-formylphenyl) terephthalate (6) to afford the corresponding 6 novel di-[3-(3-alkyl/aryl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)- azomethinphenyl] isophthalates (4) and 6 novel di-[3-(3-alkyl/aryl-4,5- dihydro-1H-1,2,4-triazol-5-one-4-yl)-azomethinphenyl] terephthalates (7), respectively. The acetylation reactions of compounds 4 and 7 were investigated, and 5 and 8 type compounds were obtained, respectively. The new compounds synthesized were characterized by using IR, ^1H-NMR, ^{13}C-NMR, and UV spectral data together with elemental analysis. In addition, to investigate the effects of solvents and molecular structure upon acidity, compounds 4 and 7 were titrated potentiometrically with tetrabutylammonium hydroxide in 5 non-aqueous solvents (isopropyl alcohol, tert-butyl alcohol, N,N-dimethylformamide, acetone, …
Microwave-Assisted Synthesis Of 1,4´-Diazaflavone And N-Alkyl Derivative Pigments With Anti-Microbial Activity, Nuran Yayli, Osman Üçüncü, Nuretti̇n Yayli, Emi̇ne Demi̇r, Zi̇hni̇ Demi̇rbağ
Microwave-Assisted Synthesis Of 1,4´-Diazaflavone And N-Alkyl Derivative Pigments With Anti-Microbial Activity, Nuran Yayli, Osman Üçüncü, Nuretti̇n Yayli, Emi̇ne Demi̇r, Zi̇hni̇ Demi̇rbağ
Turkish Journal of Chemistry
1,4'-Diazaflavone pigment (2) was synthesized by a simple environmentally friendly microwave-assisted one-pot method for the cyclization of 2'-amino (E)-4''-aza-chalcone (1) under solventless conditions using K-10 clay. In addition, 10 new N-alkyl (C_{5-12, 14-15}) substituted 1,4' -diazaflavonium bromide pigments (3-12) were prepared from compound 2 or directly from compound 1, with corresponding alkyl halides in acetonitrile under reflux. The anti-microbial activity of compounds 1-12 was tested. The N-alkyl substituted 1,4' -diazaflavonium bromides (3-12) showed good antimicrobial activity against the gram-positive bacteria tested with minimal bactericidal concentration (MBC) values for the reference antibiotic kanamycin. The optimum length of the alkyl chain for …
Concentration Of Phosphorylated Proteins Using Modified Pmma Microanalytical Devices, Jowell Guerra Bolivar
Concentration Of Phosphorylated Proteins Using Modified Pmma Microanalytical Devices, Jowell Guerra Bolivar
LSU Doctoral Dissertations
This work describes the application of PMMA-based microanalytical devices for the affinity-type preconcentration of posttranslational modified proteins (PTMs). The choice of poly(methyl methacrylate), PMMA, is based on its biocompatibility, its functional methyl ester group for potential modification, and its extensive applications to create biological microelectromechanical systems (BioMEMS). Developing methodologies for preconcentration of PTMs is important for cancer diagnosis due to PTMs’ influence in the regulatory mechanism underlying the early stage of apoptosis or regulated cell death. Towards this goal, nitroavidin which can reversibly binds to biotin (and biotinylated proteins), was prepared using reported procedure and was characterized using several techniques …
Solid-Phase Synthesis Of Asymmetrically Substituted Phthalocyanines, Sultan Sibel Erdem
Solid-Phase Synthesis Of Asymmetrically Substituted Phthalocyanines, Sultan Sibel Erdem
LSU Doctoral Dissertations
Phthalocyanines (Pcs) are excellent candidates for use as fluorophores for near-infrared (near-IR) fluorescent tagging of biomolecules and as photodynamic therapy (PDT) agents. Synthesis of Pcs with asymmetrical substitution on the periphery is often difficult due to the problems during the purification of the Pc mixtures obtained. The objective of this project is to design and synthesize chemically robust near-IR fluorophores for bioanalytical applications and to develop new synthetic methods for rapid synthesis of the target compounds. A novel synthetic route was developed utilizing a hydrophilic, polyethylene glycol-based (PEG) support with different types of linkers. The Pcs were functionalized with either …
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
LSU Doctoral Dissertations
The goal of this dissertation was to demonstrate collection, detection and identification of microorganisms from bioaerosols using offline matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the analysis of proteins. MALDI-MS intact bacteria techniques were adapted for use with an orthogonal MALDI quadrupole-time-of-flight mass spectrometer. Results indicate the instrument is capable of analyzing intact whole-cells. The first phase was to evaluate three bioaerosol samplers, an Andersen N6 single-stage impactor (AI), a cyclone impactor, and a vacuum filter system. The samplers collected test bioaerosols using a constructed bioaerosol exposure chamber (BEC). The BEC allowed all three samplers to operate in parallel. Each …
Development Of New Stimuli-Responsive Vesicles Using A Novel Surfactant, Yuming Yang
Development Of New Stimuli-Responsive Vesicles Using A Novel Surfactant, Yuming Yang
LSU Doctoral Dissertations
Many amphiphilic molecules (surfactants) possess the ability to aggregate in aqueous solution to form thermodynamically stable aggregates that have potential for use as molecule containers and delivery systems in analytical or pharmaceutical applications. However, it is difficult to release the encapsulated molecules from these aggregates under a controllable manner, and this problem has dramatically limited the application of these aggregated systems. This study addresses this problem through fundamental structure modification by development of a novel redox stimuli-responsive amphiphile capable of forming vesicle aggregates. Aggregate structure can be adjusted through redox stimulation. The release of agents from the core of the …
Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu
Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu
LSU Doctoral Dissertations
The synthesis and sequential surface characterization of silica-polypeptide composite particles is described. Nearly monodisperse colloidal silica cores were obtained by the alkaline hydrolysis of tetraethyl orthosilicate (TEOS). The hydrodynamic radius can be easily controlled in the range of ƒî 20-140 nm by the water/TEOS ratio in the starting reaction mixture. The surface of the synthesized silica cores was further passivated/functionalized (P/F) by a mixture of (3-aminopropyl) trimethoxysilane (APS) and methyl-trimethoxysilane (MTMS). The amino groups were quantified using UV-Vis spectrometry after reaction with ninhydrin. The use of zeta potential measurements of the P/F silica particles at low pH is presented as …
Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett
Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett
LSU Doctoral Dissertations
Material properties of industrial polymer blends are of great importance. X-ray tomography has been used to obtain spatial chemical information about various polymer blends. The spatial images are acquired with synchrotron X-ray tomography because of its rapidity, good spatial resolution, large field-of-view, and elemental sensitivity. The spatial absorption data acquired from X-ray tomography experiments is converted to spatial chemical information via a linear least squares fit of multi-spectral X-ray absorption data. A fiberglass-reinforced polymer blend with a new-generation flame retardant is studied with multi-energy synchrotron X-ray tomography to assess the blend homogeneity. Relative to other composite materials, this sample is …
Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne
Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne
LSU Doctoral Dissertations
A diverse set of human diseases is associated with the misfolding of proteins into insoluble fibrillar structures that have predominantly β-sheet secondary structure. Thus it is imperative to elucidate the structural elements that contribute to β-sheet formation and stability. Peptides that autonomously form β-sheets are ideal models to study principles of protein folding and design. Gellman and coworkers first introduced an automonously folded β-hairpin (H-Arg-Tyr-Val-Glu-Val-Yyy-Xxx-Orn-Lys-Ile-Leu-Gln-NH2) that remained monomeric up to ~1 mM. Circular dichroism (CD) and nuclear magnetic resonance (NMR) analyses revealed that incorporation of non-stereogenic Aib-Xxx dipeptidyl sequences into i+1 and i+2 positions of a model peptide nucleates a …
Retro Models Of The Cisplatin-Dna Cross-Link With Carrier Ligands Having Sp2 N-Donor Triazine Rings, Vidhi Maheshwari
Retro Models Of The Cisplatin-Dna Cross-Link With Carrier Ligands Having Sp2 N-Donor Triazine Rings, Vidhi Maheshwari
LSU Doctoral Dissertations
Rapid rotation of guanine base derivatives about Pt–N7 bonds results in fluxional behavior of models of the key DNA intrastrand G–G cross-link leading to anticancer activity of Pt(II) drugs (G = deoxyguanosine). This behavior impedes the characterization of LPtG2 models (L = one bidentate or two cis-unidentate carrier ligands; G = guanine derivative). The objective of this study is to understand the types of conformers formed as L is systematically varied. This work, relevant to Pt(II) anticancer drugs, has evolved from published studies with sp3 N-ligands (e.g., 2,2'-bipiperidine), to C2 symmetrical or unsymmetrical sp2 N-ligands having pyridine and/or triazine rings. …
Gas-Phase Formation Of Environmentally Persistent Free Radicals From Thermal Degradation Of Catechol, Hydroquinone, Phenols And Tobacco, Julien Gnonlonfoun Adounkpe
Gas-Phase Formation Of Environmentally Persistent Free Radicals From Thermal Degradation Of Catechol, Hydroquinone, Phenols And Tobacco, Julien Gnonlonfoun Adounkpe
LSU Doctoral Dissertations
Catechol, hydroquinone and Phenol are major constituents of the mainstream tobacco smoke. The toxicity of tobacco has been attributed to the ability of catechol and hydroquinone to undergo endogenous or exogenous redox cycling to form semiquinone type radicals responsible of Reactive Oxygen Species (ROS) formation. ROS such as hydroxyl radicals can cause severe oxidative stress on biological tissues and can provoke severe signaling pathways leading to cardiovascular and pulmonary dysfunctions and carcinogenesis. Given that semiquinone type radicals are organic radicals, characterized by their high instability and reactivity; it is somewhat surprising that they can live long enough mostly when associated …