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2005

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Articles 511 - 540 of 562

Full-Text Articles in Chemistry

Polystyrene Nanocomposites Based On Carbazole-Containing Surfactants, Grace Chigwada, David D. Jiang, Charles A. Wilkie Jan 2005

Polystyrene Nanocomposites Based On Carbazole-Containing Surfactants, Grace Chigwada, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

New organically-modified clays containing a carbazole unit were prepared and the number of long alkyl chains on the surfactant was varied. The clay was used to prepare polystyrene nanocomposites by both bulk polymerization and melt blending. The dispersion of these clays in the polymer matrix was evaluated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability of the clays and the nanocomposites were analyzed by thermogravimetric analysis (TGA) while the fire properties were evaluated by cone calorimetry. If more than two alkyl chains were present, the gallery spacing is apparently overcrowded, leading to poor dispersion. Bulk polymerization …

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The Relationship Between The Solubility Parameter Of Polymers And The Clay-Dispersion In Polymer/Clay Nanocomposites And The Role Of The Surfactant, Bok Nam Jang, Dongyan Wang, Charles A. Wilkie Jan 2005

The Relationship Between The Solubility Parameter Of Polymers And The Clay-Dispersion In Polymer/Clay Nanocomposites And The Role Of The Surfactant, Bok Nam Jang, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites were prepared of polymers having different solubility parameters and pristine or organically modified clays, and the dispersion of clay in the polymer was evaluated using X-ray diffraction and transmission electron microscopy. The solubility parameters of both the polymers and surfactants of interest were calculated according to the group contribution method and correlated with the clay morphology. A close relationship between the solubility parameter of the polymer and the clay morphology was observed. The clay has a very polar group, so the higher is the solubility parameter of the polymer, the larger is the d spacing of the clay that …

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Optimization Of An Acrylamides-Based Photopolymer For Reflection Holographic Recording, Raghavendra Jallapuram Jan 2005

Optimization Of An Acrylamides-Based Photopolymer For Reflection Holographic Recording, Raghavendra Jallapuram

Doctoral

Photopolymers have been the subject of special attention in the last two decades. The advantage of being self-developing makes them a practical alternative to silver halide photographic emulsions in holographic interferometry applications. This thesis is aimed at understanding diffusion properties and optimization of an acrylamide-based green sensitized photopolymer material for reflection holographic recording. The composition of the photopolymer includes a green sensitive dye (erythrosine B), acrylamide (monomer), electron donor (triethanolamine) a cross linking monomer (NN’methylenebisacrylamide) and a binder (polyvinyl alcohol). On illumination with light of the appropriate wavelength the dye absorbs a photon and enters into an excited state. The …

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Analytical Separations Using Polymetric Surfactants, Mary Waithira Kamande Jan 2005

Analytical Separations Using Polymetric Surfactants, Mary Waithira Kamande

LSU Doctoral Dissertations

The goal of the research presented in this dissertation is to develop effective analytical methods for the separation of both achiral and chiral analytes using polymeric surfactants. Three analytical techniques are employed to accomplish this objective: open-tubular capillary electrochromatography (OT-CEC), open-tubular capillary electrochromatography coupled to mass spectrometry (OT-CEC/MS), and micellar affinity gradient focusing (MAGF). This research work presents novel application of polymeric surfactants that contributes to improved separations of difficult to separate analytes. The first part focuses on the application of an achiral polyelectrolyte multilayer (PEM) coating using OT-CEC. The PEM coating consisting of the cationic polymer poly (diallyldimethylammonium chloride), …

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An Evaluation Of The Enantiomeric Recognition Of Amino Acid Based Polymeric Surfactants And Cyclodextrins Using Spectroscopic And Chromatographic Methods, Bertha Cedillo Valle Jan 2005

An Evaluation Of The Enantiomeric Recognition Of Amino Acid Based Polymeric Surfactants And Cyclodextrins Using Spectroscopic And Chromatographic Methods, Bertha Cedillo Valle

LSU Doctoral Dissertations

The scope of this dissertation is to explore the enantiomeric recognition properties of amino acid based polymeric surfactants using a combination of analytical techniques including chromatographic and spectroscopic methods. Chapter 1 includes an introduction to chirality and chiral separations using capillary electrophoresis. Using cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC), the enantioseparation of three binaphthyl derivatives using native alpha- and beta-cyclodextrins in combination with various diastereomers of chiral polymeric surfactants (PS) was examined. A reversal of enantiomeric order was observed with the enantiomers of (1,1 S-binaphthyl-2,2 S-diamine (BNA) and (1,1 S-binaphthol (BOH) due to a competition between the two chiral selectors …

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The Stereoselective Synthesis Of The Butyrolactone-Bridged [8-5-5] Tricyclic Ring Systems Of (+/-)-Asteriscanolide Via The Titanium-Mediated Hetero-Pauson-Khand Reaction, Mohamed G. Sherriff Jan 2005

The Stereoselective Synthesis Of The Butyrolactone-Bridged [8-5-5] Tricyclic Ring Systems Of (+/-)-Asteriscanolide Via The Titanium-Mediated Hetero-Pauson-Khand Reaction, Mohamed G. Sherriff

LSU Doctoral Dissertations

The stereoselective construction of the tricyclic ring system of asteriscanolide from cyclooctadiene has been achieved. The synthesis involves two main steps; the synthesis of the aldehyde precursor(5)and the titanium-mediated cabocyclization of 5 to make the three rings of 43 stereoselectively.

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Shear Induced Orientation In Polymer-Clay Solutions And Their Influence On The Structure In Multilayered Films, Matthew Michael Malwitz Jan 2005

Shear Induced Orientation In Polymer-Clay Solutions And Their Influence On The Structure In Multilayered Films, Matthew Michael Malwitz

LSU Doctoral Dissertations

The influence of shear on viscoelastic solutions of poly(ethylene oxide) (PEO) and clay (Cloisite, CNA) was investigated by rheology and small angle neutron scattering (SANS) under shear. These measurements determined the shear-induced orientation of the clay and the polymer as well as their relaxation behavior after cessation of shear. Comparison of PEO-CNA solutions (~100 nm diameter platelets) to previously studied PEO-Laponite gels (~30 nm diameter platelets) found that the orientation of CNA platelets occurs at much lower shear rates. Additionally, the relaxation times were much longer for CNA platelets than for Laponite platelets. From these solutions and gels, multilayered nanocomposite …

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The Thermal Degradation Of Bisphenol A Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie Jan 2005

The Thermal Degradation Of Bisphenol A Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of polycarbonate in air was studied as a function of mass loss using TGA/FTIR, GC/MS and LC/MS. In the main degradation region, 480–560 °C, the assigned structures of smaller molecules and linear molecules that evolved in air were very similar to those obtained from the degradation in nitrogen; the degradation of polycarbonate follows chain scission of the isopropylidene linkage, in agreement with the bond dissociation energies, and hydrolysis/alcoholysis of carbonate linkage. Compared to the degradation in nitrogen, some differences were observed primarily in the beginning stage of degradation. Oxygen may facilitate branching as well as radical formation …

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The Effects Of Triphenylphosphate And Recorcinolbis(Diphenylphosphate) On The Thermal Degradation Of Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie Jan 2005

The Effects Of Triphenylphosphate And Recorcinolbis(Diphenylphosphate) On The Thermal Degradation Of Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of polycarbonate/triphenylphosphate (PC/TPP) and PC/resocinolbis(diphenylphosphate) (PC/RDP) in air has been studied using TGA/FTIR and GC/MS. In PC/phosphate blends, the phosphate stabilizes the carbonate group of polycarbonate from alcoholysis between the alcohol products of polycarbonate degradation and the carbonate linkage. Thus, the evolution of bisphenol A, which is mainly produced via hydrolysis/alcoholysis of the carbonate linkage, is significantly reduced, while, the evolution of various alkylphenols and diarylcarbonates increases. The bonds that are broken first in the thermal degradation of both the carbonate and isopropylidene linkages of polycarbonate are the weakest bonds in each, when a phosphate is present. …

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Polyethylene And Polypropylene Nanocomposites Based Upon An Oligomerically-Modified Clay, Jinguo Zhang, David D. Jiang, Charles A. Wilkie Jan 2005

Polyethylene And Polypropylene Nanocomposites Based Upon An Oligomerically-Modified Clay, Jinguo Zhang, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Montmorillonite clay was modified with an oligomeric surfactant, which was then melt blended with polyethylene and polypropylene in a Brabender mixer. The morphology was characterized by X-ray diffraction and transmission electron microscopy, while thermal stability was evaluated from thermogravimetric analysis and the fire properties by cone calorimetry. The nanocomposites are best described as mixed immiscible/intercalated/delaminated systems and the reduction in peak heat release rate is about 40% at 5% inorganic clay loading.

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Isolation, X-Ray Structures, And Electronic Spectra Of Reactive Intermediates In Friedel−Crafts Acylations, M. G. Davlieva, Sergey V. Lindeman, I. S. Neretin, Jay K. Kochi Jan 2005

Isolation, X-Ray Structures, And Electronic Spectra Of Reactive Intermediates In Friedel−Crafts Acylations, M. G. Davlieva, Sergey V. Lindeman, I. S. Neretin, Jay K. Kochi

Chemistry Faculty Research and Publications

Reactive intermediates in the Friedel−Crafts acylation of aromatic donors are scrutinized upon their successful isolation and X-ray crystallography at very low temperatures. Detailed analyses of the X-ray parameters for the [1:1] complexes of different aliphatic and aromatic-acid chlorides with the Lewis acids antimony pentafluoride and pentachloride, gallium trichloride, titanium and zirconium tetrachlorides provide unexpected insight into the activation mechanism for the formation of the critical acylium carbocations. Likewise, the X-ray-structure examinations of aliphatic and aromatic acylium electrophiles also isolated as crystalline salts point to the origins of their electrophilic reactivity. Although the Wheland intermediates (as acylium adducts to arene donors) …

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Isolation And X-Ray Structures Of Labile Benzoic- And Acetic-Acidium Carbocations, Sergey V. Lindeman, I. S. Neretin, M. G. Davlieva, Jay K. Kochi Jan 2005

Isolation And X-Ray Structures Of Labile Benzoic- And Acetic-Acidium Carbocations, Sergey V. Lindeman, I. S. Neretin, M. G. Davlieva, Jay K. Kochi

Chemistry Faculty Research and Publications

New carbocationic salts (via O-protonation of substituted benzoic acids) are prepared for the first time by controlled hydration of the corresponding benzoylium salts and isolated in pure crystalline form. Precise X-ray structural analyses reveal the rather unexpected (electronic) structure of the carboxylic-acidium functionality.

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Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga Jan 2005

Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga

LSU Doctoral Dissertations

Since polymer modified asphalt cement (PMAC) has been employed for a decade, the lifetime and wear on some of these pavements is reaching a stage where resurfacing is necessary. This research focuses on the characterization of aged polymer modified asphalt cements (PMAC) to evaluate their potential for recycling. A styrene-butadiene-styrene tri-block (SBS) polymer modified asphalt cement was selected and characterized using standard asphalt binder qualification techniques, i.e., the Superpave PG protocol. We developed a procedure to characterize the relative concentration of polymer in asphalt cements by gel permeation chromatography (GPC). Infrared spectrographic, thermogravimetric and rheological techniques were used to identify …

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Detection Of Biologically Important Molecules, Kyukwang Kim Jan 2005

Detection Of Biologically Important Molecules, Kyukwang Kim

LSU Doctoral Dissertations

Anions play important roles in biological systems. The design of anion sensors has been of great interest. The selective detection of a specific anion is particularly challenging. In the first chapter, I describe the synthesis of a TBS-protected fluorescein dye (1.1) and its use for the selective detection of fluoride. Solutions of 1.1 either in DCM or in aqueous media at physiological pH show the excellent selectivity towards fluoride to afford color formation while solutions of other interfering anions remain colorless. The monitoring of homocysteine (Hcy) and cysteine (Cys) levels is important since they are biomarkers associated with Alzheimer’s and …

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Design And Cloning Of A Hammerhead Ribozyme Targeted Tohiv-1p7fmrna, Katherine L. Anderson, William H. Jackson Jan 2005

Design And Cloning Of A Hammerhead Ribozyme Targeted Tohiv-1p7fmrna, Katherine L. Anderson, William H. Jackson

Journal of the South Carolina Academy of Science

No abstract provided.

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High Performance Liquid Chromatography Diastereomeric Separation For Chiral Analysis And Kinetic Analysis, Li Li Jan 2005

High Performance Liquid Chromatography Diastereomeric Separation For Chiral Analysis And Kinetic Analysis, Li Li

Seton Hall University Dissertations and Theses (ETDs)

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Examination Of Some Organic Explosives By Ion Mobility Spectrometry (Ims), Hülya Koyuncu, Ertan Seven, Ayla Çalimli Jan 2005

Examination Of Some Organic Explosives By Ion Mobility Spectrometry (Ims), Hülya Koyuncu, Ertan Seven, Ayla Çalimli

Turkish Journal of Chemistry

The increase in terrorist activities committed using explosives in recent years has generated the need for improved analytical methods that can accurately and quickly identify explosives and their residues. In this study such an analytical method is evaluated. In the first phase of the study, standard solutions and a standard mixture solution of TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazocyclohexane), PETN (pentaerythritoltetranitrate) and TETRYL (2,4,6-trinitrophenylmethylnitramine) were examined using ion mobility spectrometry (IMS). In the second phase, qualitative analysis of a real explosion residue was carried out and the explosive material used in the bomb was identified by analysing the acetone extract. In the …

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Phlinoside F, A New Phenylethanoid Glycoside From Phlomis Angustissima, Funda Nuray Yalçin, Tayfun Ersöz, Erdal Bedi̇r, Sevser Şahpaz, François Bailleul, Ikhlas A. Khan, Ali̇ Arslan Dönmez, İhsan Çaliş Jan 2005

Phlinoside F, A New Phenylethanoid Glycoside From Phlomis Angustissima, Funda Nuray Yalçin, Tayfun Ersöz, Erdal Bedi̇r, Sevser Şahpaz, François Bailleul, Ikhlas A. Khan, Ali̇ Arslan Dönmez, İhsan Çaliş

Turkish Journal of Chemistry

From the overground parts of Phlomis angustissima, a new phenylethanoid triglycoside, \beta-(3-hydroxy,4-methoxyphenyl)ethyl- O-[\beta -xylopyranosyl(1 \to 2)-\alpha -rhamnopyranosyl-(1 \to 3)] -O-4-O-feruloyl-\beta -glucopyranoside, named phlinoside F, was isolated along with the known compounds alyssonoside, samioside, lamiide, auroside, naringenin, and syringaresinol-4-O-\beta -D-glucopyranoside. The structure of the new glycoside was elucidated by spectroscopic methods.

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Selective Oxidation Of Thiols To Disulfides Catalyzed By Iron(Iii) -- Tetra Phenyl Porphyrin Using Urea-Hydrogen Peroxide As Oxidizing Reagent, Bahador Karimi, Morteza Montazerozohori, Majid Moghadam, Mohammad Hosein Habibi, Khodabakhsh Niknam Jan 2005

Selective Oxidation Of Thiols To Disulfides Catalyzed By Iron(Iii) -- Tetra Phenyl Porphyrin Using Urea-Hydrogen Peroxide As Oxidizing Reagent, Bahador Karimi, Morteza Montazerozohori, Majid Moghadam, Mohammad Hosein Habibi, Khodabakhsh Niknam

Turkish Journal of Chemistry

Oxidation of thiols to disulfides catalyzed by iron(III) -- tetra phenyl prophyrin Fe (TPP)Cl was investigated using urea-hydrogen peroxide adduct (UHP) as an oxidant in methanol as a solvent.

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Miscibility Of Methylmethacrylate-Co-Methacrylic Acid Polymer With Magnesium, Zinc, And Manganese Sulfonated Polystyrene Ionomers, Cemi̇l Alkan, Nebahat Yurtseven, Leyla Aras Jan 2005

Miscibility Of Methylmethacrylate-Co-Methacrylic Acid Polymer With Magnesium, Zinc, And Manganese Sulfonated Polystyrene Ionomers, Cemi̇l Alkan, Nebahat Yurtseven, Leyla Aras

Turkish Journal of Chemistry

The miscibility of methyl methacrylate-co-methacrylic acid polymer (MMA-MAA) with metal neutralized sulfonated polystyrene ionomers was investigated by viscometry, differential scanning calorimetry (DSC), and Fourier transform infrared radiation spectroscopy (FTIR) techniques. Polystyrene (PS) was sulfonated by acetic anhydride and sulfuric acid and the sulfonation degree was found to be 2.6 mole percent, and 2.6 mole percent sulfonated polystyrene was neutralized by Mg, Zn, and Mn salts. The miscibility behavior of the blends of MMA-MAA with Mg neutralized 2.6 mole% sulfonated polystyrene (2.6MgSPS), Mn neutralized 2.6mole% sulfonated polystyrene (2.6MnSPS), and Zn neutralized 2.6 mole% sulfonated polystyrene (2.6ZnSPS) was investigated by dilute solution …

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A General Synthesis Of Tris-Indole Derivatives As Potential Iron Chelators, R. Bryan Sears, Russell A. Carpenter, Christine R. Whitlock Jan 2005

A General Synthesis Of Tris-Indole Derivatives As Potential Iron Chelators, R. Bryan Sears, Russell A. Carpenter, Christine R. Whitlock

Chemistry: Faculty Publications (1990-2023)

The development of a novel route for the synthesis of a new class of compounds is described. The first tripodal, tris-indole amines are prepared by straightforward routes.

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Study Of The Electronic Structure Of Cafeo₃, Jinbo Yang, M. S. Kim, Qingsheng Cai, X.-D. Zhou, Harlan U. Anderson, William Joseph James, William B. Yelon Jan 2005

Study Of The Electronic Structure Of Cafeo₃, Jinbo Yang, M. S. Kim, Qingsheng Cai, X.-D. Zhou, Harlan U. Anderson, William Joseph James, William B. Yelon

Materials Science and Engineering Faculty Research & Creative Works

We have studied the charge disproportionation phenomenon in CaFeO3 using the local-spin density approximation with the on-site Coulomb interaction parameter U and exchange parameter J. The calculation reveals that the total number of the 3d electrons is about 5.1 for both Fe(1)(Fe5+) and Fe(2)(Fe3+) atoms, and that there are about 0.25 electron holes in the O-2p band. Therefore, the charge disproportionation can be more accurately described as 2d5L(Fe4+)=d5L2(Fe5+)+d5(Fe3+), where L denotes a hole in the oxygen 2p band, instead of 2d4(Fe4+)=d3(Fe5+)+d5(Fe3+). The hybridization between the Fe-3d and O-2p orbitals is stronger for Fe(1) than for Fe(2) due to the shorter …

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Environment Friendly Organic Synthesis Using Bismuth Compounds. An Efficient Method For Carbonyl-Ene Reactions Catalyzed By Bismuth Triflate, Ram Mohan, Erin Anderson, Justin Ernat, Mai Nguyen, Ann Palma Jan 2005

Environment Friendly Organic Synthesis Using Bismuth Compounds. An Efficient Method For Carbonyl-Ene Reactions Catalyzed By Bismuth Triflate, Ram Mohan, Erin Anderson, Justin Ernat, Mai Nguyen, Ann Palma

Scholarship

Bismuth triflate (0.1 mol %) is a highly efficient catalyst for the cyclization of citronellal 1, a reaction that yields a ratio of 80:20 of isopulegol 2 and neoisopulegol 3. This methodology has also been extended to the synthesis of substituted piperidines. The bismuth triflate catalyzed ene reaction of aldehyde 4 gives a 70:30 mixture of piperidines 5 and 6. The advantages of these methods include the use of a highly efficient catalyst that is relatively nontoxic, cheap and easy to handle.

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The Discovery-Oriented Approach To Organic Chemistry. 6. Selective Reduction In Organic Chemistry: Reduction Of Aldehydes In The Presence Of Esters Using Sodium Borohydride, Ram Mohan, Ashvin Baru Jan 2005

The Discovery-Oriented Approach To Organic Chemistry. 6. Selective Reduction In Organic Chemistry: Reduction Of Aldehydes In The Presence Of Esters Using Sodium Borohydride, Ram Mohan, Ashvin Baru

Scholarship

Chemoselective reductions are valuable in organic synthesis and are routinely discussed in a sophomore organic chemistry course. Yet, there are few examples of laboratory experiments that illustrate such chemoselectivity. A reaction that is routinely discussed in sophomore organic chemistry is the selective reduction of aldehydes and ketones using sodium borohydride. Esters are typically not affected by NaBH4. However, none of the lab experiments reported to date illustrate this chemoselectivity (1). We have developed a discovery-oriented lab experiment that illustrates the chemoselective nature of reductions using sodium borohydride. The experiments involve the reduction of vanillin acetate (Scheme I) …

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On-Road Emissions In Asia Measured By Remote Sensing (Presentation), Donald H. Stedman, Gary A. Bishop Jan 2005

On-Road Emissions In Asia Measured By Remote Sensing (Presentation), Donald H. Stedman, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

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Nmr And Modulated Differential Scanning Calorimetry Of Adsorbed Poly(Methyl Acrylate) On Silica, Frank D. Blum, Burak Metin Jan 2005

Nmr And Modulated Differential Scanning Calorimetry Of Adsorbed Poly(Methyl Acrylate) On Silica, Frank D. Blum, Burak Metin

Chemistry Faculty Research & Creative Works

The interaction between polymers and solid substrates can be studied by a variety of techniques. The results from different experiments can be affected by the nature of the polymer, surface, polymer-surface interactions and, also, the experiment. A great deal has been learned about the behavior of polymers at interfaces, but there is also much to be learned about the interactions and how they affect the physical properties of adsorbed polymers. In the present study, we report both deuterium nuclear magnetic resonance (NMR) and modulated differential scanning calorimetry (MDSC) of poly(methyl acrylate) (PMA) adsorbed on Cab-O-Sil silica. The focus of this …

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Coupled Electrical And Magnetic Properties In (La,Sr)Feo3-Δ, X.-D. Zhou, Qingsheng Cai, Jinbo Yang, M. S. Kim, William B. Yelon, William Joseph James, Y.-W. Shin, B. J. Scarfino, Harlan U. Anderson Jan 2005

Coupled Electrical And Magnetic Properties In (La,Sr)Feo3-Δ, X.-D. Zhou, Qingsheng Cai, Jinbo Yang, M. S. Kim, William B. Yelon, William Joseph James, Y.-W. Shin, B. J. Scarfino, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

This article is aimed at studying the temperature dependence oxygen nonstoichiometry, magnetic moments, Fe3+ fraction, Néel temperature and conductivity of (La,Sr)FeO3-δ. It is found that the magnetic properties in La0.60 Sr0.40 Fe3-δ is determined by Fe3+ and its concentration, and the conductance is resulted from Fe4+ ions, which act as electron holes. Both of magnetic and electrical properties were directly governed by oxygen nonstoichiometry (δ). when δ=0.2, the compound has maximum Fe3+, the saturation magnetic moments and Néel temperature are 3.8 µB and 410 °C, both at the highest level, …

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Structure, Magnetic, And Transport Properties Of Ti-Substituted La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William Joseph James, William B. Yelon, D. Buddhikot, Satish K. Malik, Paul Ernest Parris Jan 2005

Structure, Magnetic, And Transport Properties Of Ti-Substituted La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William Joseph James, William B. Yelon, D. Buddhikot, Satish K. Malik, Paul Ernest Parris

Materials Science and Engineering Faculty Research & Creative Works

Ti-substituted perovskites La0.7Sr0.3Mn1-xTixO3 with 0 ≤ x ≤ 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3c) from 10 K to room temperature. At room temperature, the cell parameters a,c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x > 0.10, while the unit cell volume remains nearly constant for x > 0.10. The average (Mn,Ti)-O bond length increases …

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Synthesis And Characterization Of Mercury Vapor Coordination Species Using 1,3-Benzenedioethanethiolate (Bdet), Elizabeth Zuchek, Harvest L. Collier Jan 2005

Synthesis And Characterization Of Mercury Vapor Coordination Species Using 1,3-Benzenedioethanethiolate (Bdet), Elizabeth Zuchek, Harvest L. Collier

Opportunities for Undergraduate Research Experience Program (OURE)

Mercury is a major pollutant in the air today. Some possible chelators that have been used are British anti-Lewisite (BAL) 2,3-dimercaptopropanol, dimercaptosuccinic acid (DMSA). diinercaptopropanesulfonic acid (DMPS). and 1,3-benzenediamidoethanethiolate (BDE'I1. All contain two thiol groups, which 'capture' the heavy mercury element. Due to their structure, they all differ in how well they bind to the mercury atom. BDET is the most recent and efficient chelate used. Statistics show that coal-fired power plants are the nation's largest mercury polluter. Steps have been taken to lower the emission of this toxic metal by the Clean Air Act. However, recently The Bush Administration's …

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Photocontrol Of Upper And Lower Rim Complexation Of Neutral And Cationic Species By P-Tert-Butylcalix[4]Arene Tetraethyl Ester, Mary Deasy, Bernadette Creaven, Brian A. Murray, Catherine Mckenna, Darren Tobin Jan 2005

Photocontrol Of Upper And Lower Rim Complexation Of Neutral And Cationic Species By P-Tert-Butylcalix[4]Arene Tetraethyl Ester, Mary Deasy, Bernadette Creaven, Brian A. Murray, Catherine Mckenna, Darren Tobin

Articles

A number of sodium salt complexes of p-tert-butylcalix[4]arene tetraethyl ester, 1, were isolated both with and without upper-rim encapsulated solvent. Selective decomplexation of lower rim bound sodium cations and upper rim encapsulated solvent molecules could be successfully achieved using low pressure light sources. Oxidation of the counter anion at the lower rim of p-tert-butylcalix[4]arene tetraethyl ester triggered both the upper and lower rim decomplexation process. The extent of decomplexation at both rims is controlled both by the nature of the counter-anionic species at the lower rim and by the fate of the photoproducts generated. The calixarene host …

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