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Articles 151 - 176 of 176

Full-Text Articles in Chemistry

Combined Single-Molecule Photon-Stamping Spectroscopy And Femtosecond Transient Absorption Spectroscopy Studies Of Interfacial Electron Transfer Dynamics, Lijun Guo, Yuanmin Wang, H. Peter Lu Feb 2010

Combined Single-Molecule Photon-Stamping Spectroscopy And Femtosecond Transient Absorption Spectroscopy Studies Of Interfacial Electron Transfer Dynamics, Lijun Guo, Yuanmin Wang, H. Peter Lu

Chemistry Faculty Publications

The inhomogeneous interfacial electron transfer (IET) dynamics of 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF)-sensitized TiO2 nanoparticles (NPs) has been probed by a single-molecule photon-stamping technique as well as ensemble-averaged femtosecond transient absorption spectroscopy. The forward electron transfer (FET) time shows a broad distribution at the single-molecule level, indicating the inhomogeneous interactions and ET reactivity of the PF/TiO2 NP system. The broad distribution of the FET time is measured to be 0.4 ± 0.1 ps in the transient absorption and picoseconds to nanoseconds in the photon-stamping measurements. The charge recombination time, having a broad distribution at the single-molecule level, clearly shows a biexponential dynamic behavior …

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Some Bioactive Organotin(Iv) Derivatives With 3,4-Dichlorophenylacetic Acid: Synthesis, Spectroscopic Properties, And X-Ray Structure Of [Sn_4(C_4h_9)_8(Oocch_2c_6h_3cl_2)_4o_2], Muhammad Adeel Saeed, Muhammad Khawar Rauf, . Imtiaz-Ud-Din, Amin Badshah, Muhammad Zaeem Akhtar, Bushra Mirza Jan 2010

Some Bioactive Organotin(Iv) Derivatives With 3,4-Dichlorophenylacetic Acid: Synthesis, Spectroscopic Properties, And X-Ray Structure Of [Sn_4(C_4h_9)_8(Oocch_2c_6h_3cl_2)_4o_2], Muhammad Adeel Saeed, Muhammad Khawar Rauf, . Imtiaz-Ud-Din, Amin Badshah, Muhammad Zaeem Akhtar, Bushra Mirza

Turkish Journal of Chemistry

Some bioactive organotin(IV) derivatives of 3,4-dichlorophenylacetic acid (HL) were synthesized by reacting the ligand acid with various di- or tri-organotin compounds (in suitable mole ratios) in the presence of triethylamine. The structural investigation was carried out via multinuclear (^1H, ^{13}C, and ^{119}Sn) NMR, IR spectroscopy, and X-ray crystallography. The crystal structure of 4 comprises a central Sn_2O_2 core with O atoms bonded to 2 dibutylbis(3,4-dichlorophenylacetato)tin(IV) units. All the Sn atoms of 4 are essentially 5-coordinated in distorted trigonal-bipyramidal geometry. Some of the compounds exhibited significant antibacterial and antifungal activity.

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Electrochemical Properties Of 1-(O-, M-, P-Nitrophenyl)-3-(M-Nitrophenyl)- 5-Phenylformazans And Their Nickel Complexes, Habi̇be Tezcan, Mehmet Levent Aksu Jan 2010

Electrochemical Properties Of 1-(O-, M-, P-Nitrophenyl)-3-(M-Nitrophenyl)- 5-Phenylformazans And Their Nickel Complexes, Habi̇be Tezcan, Mehmet Levent Aksu

Turkish Journal of Chemistry

The electrochemical properties of NO_2 formazans and their Ni(II) complexes were investigated. The investigated formazans included a NO_2 group at the o-, m-, and p-positions of the 1-phenyl ring and at the m-position of the 3-phenyl ring. The oxidation and reduction peak potentials, number of electrons transferred, diffusion coefficient, heterogeneous rate constant, and possible reaction mechanism of the compounds were determined with the use of cyclic voltammetry (CV), ultramicrodisc electrodes (UMEs), and chronoamperometry (CA). The peak potentials (E}_{ox1}) were observed to shift towards more anodic potentials in formazans and more cathodic potentials in their respective Ni complexes compared to unsubstituted …

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Elucidating The Structure Of Protein Aggregates By Raman Spectroscopy, Ludmila A. Popova Jan 2010

Elucidating The Structure Of Protein Aggregates By Raman Spectroscopy, Ludmila A. Popova

Legacy Theses & Dissertations (2009 - 2024)

The structures and properties of amyloid fibrils are of considerable interest due to their associations with numerous neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and transmissible spongiform encephalopaties (prion diseases). Understanding fibrillogenesis at a molecular level requires detailed structural characterization of amyloid fibrils. However amyloid fibrils are difficult objects to study due to their non-crystalline and insoluble nature. These properties make the application of classical tools of structural biology, such as X-Ray crystallography and solution Nuclear Magnetic Resonance spectroscopy, impractical for structural characterization of protein fibrils.

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Synthesis And Spectroscopic Studies Of Some New Organometallic Chelates Derived From Bidentate Ligands, Kiran Singh, Parvesh Puri Jan 2010

Synthesis And Spectroscopic Studies Of Some New Organometallic Chelates Derived From Bidentate Ligands, Kiran Singh, Parvesh Puri

Turkish Journal of Chemistry

A series of organosilicon(IV) and organotin(IV) complexes having the formulae R_2MCl(L^1), R_2MCl(L^2), R_2MCl(L^3), R_2MCl(L^4), R_2M(L^1)_2, R_2M(L^2)_2, R_2M(L^3)_2, and R_2M(L^4)_2, where M = Si and Sn, and R = CH_3, were synthesized with Schiff bases 5-mercapto-4-(pyridine-2-carboxalideneamino)-s-triazole (HL^1), 4-(furfuralideneamino)-5mercapto-s-triazole (HL^2), 4-(2-chlorobenzylideneamino)-5-mercapto-s-triazole (HL^3), and 4-(4-flourobenzylideneamino)-5-mercapto-s-triazole (HL^4). These complexes were characterized by elemental analysis, molar conductance, and spectroscopic studies, including UV, IR, ^1H, ^{13}C, ^{29}Si, and ^{119}Sn NMR spectroscopy. On the basis of these studies, the resulting complexes are proposed to have trigonal bipyramidal and octahedral geometries.

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Spectroscopic Analysis Of Therapeutic Drugs., Laura Perdisatt, Christine O'Connor, Samar Moqadasi, Luke O'Neill Jan 2010

Spectroscopic Analysis Of Therapeutic Drugs., Laura Perdisatt, Christine O'Connor, Samar Moqadasi, Luke O'Neill

Conference Papers

The aim of this project was to investigate the photochemistry of three new Ruthenium (II) complexes as possible therapeutics and their associated ligands. The objectives were to use the following spectroscopic techniques: Absorption, Emission and Raman spectroscopy. Luminescent lifetime measurements were obtained by laser studies (Nd:YAG laser and Time coupled single photon counting (TCSPC) ).

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Spectroscopic Investigation Of The Anatase-To-Rutile Transformation Of Sol-Gel Synthesised Tio2 Photocatalysts, Nicholas Nolan, Suresh Pillai, Michael Seery Sep 2009

Spectroscopic Investigation Of The Anatase-To-Rutile Transformation Of Sol-Gel Synthesised Tio2 Photocatalysts, Nicholas Nolan, Suresh Pillai, Michael Seery

Articles

Among the three major phases in titania, anatase is reported to be a better photocatalytically active phase. Anatase to rutile transformations, under normal conditions, usually occurs at a temperatue range of 600- 700 °C. Various chemical additives have previously been employed to extend the anatase transition to higher temperatures. Effect of employing various concentrations of formic acid and water on phase transition has systematically been studied by XRD, FTIR and Raman spectroscopy. A considerably higher anatase phase (41%) has been obtained at 800 ºC and 10% anatase composition is retained after annealing the materials at 900 ºC for the optimised …

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Synthesis Of Complex Fluorides For Optical Applications, Seth Stepleton Aug 2009

Synthesis Of Complex Fluorides For Optical Applications, Seth Stepleton

All Dissertations

Large single crystals of alkali metal fluorides are desirable for many reasons. Fluoride laser crystals have a wide transmission range and on account of their low phonon energies, many efficient laser emissions have been obtained from 285 nm to 4.34 µm.1,2 Inorganic fluoride single crystals feature large bandgaps, very wide optical transmittance ranges from vacuum-ultraviolet (VUV) to mid-IR wavelength regions, lower refractive indices than those of oxides, and typically lower phonon energies (which drastically reduce multiphonon relaxation rates of rare earth ions).3
The main goal of this work was to investigate the hydrothermal synthesis of alkali metal fluorides. Melt techniques …

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Plants As A Source Of Green Corrosion Inhibitors: The Case Of Gum Exudates From Acacia Species (A. Drepanolobium And A. Senegal), J Buchweishaija Jul 2009

Plants As A Source Of Green Corrosion Inhibitors: The Case Of Gum Exudates From Acacia Species (A. Drepanolobium And A. Senegal), J Buchweishaija

Tanzania Journal of Science

The inhibitive performance of gum exudates from Acacia drepanolobium and Acacia senegal from Tanzania, towards the corrosion of mild steel in fresh water has been investigated. The experimental methods include potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The results indicate that gum exudates (Acacia drepanolobium and Acacia senegal) exhibit good inhibition characteristics to corrosion on mild steel under fresh water medium and the inhibition efficiency of up to 90.7% and 99.7% respectively was attained at 30 oC. Furthermore, the studies have shown that the inhibition performance remained above 90% on both Acacia exudates independent of the raise in temperature. …

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Synthesis And Spectroscopic Analysis Of Therapeutic Ru(Ii) Complexes, Samar Moqadasi, Laura Perdisatt, Christine O'Connor, Luke O'Neill Jan 2009

Synthesis And Spectroscopic Analysis Of Therapeutic Ru(Ii) Complexes, Samar Moqadasi, Laura Perdisatt, Christine O'Connor, Luke O'Neill

Conference Papers

The aim of this study is to synthesise and characterise new ligands based on a 1,10-Phenanthroline-5,6-dione backbone and their respective Ru(II) complexes; Ru(bpy)2mfmp, Ru(bpy)2fmp and Ru(bpy)2NO2-mp as shown in figure 1.The synthesis of the ligands will be discussed and a variety of Ru(II) complexes. A brief insight of the electronic and NMR spectroscopy will be presented along with preliminary photochemical results such as extinction coefficients, quantum yields and luminescence lifetimes. Ruthenium complexes have well established synthetic and photochemical properties.1The objective of this work is to synthesise Ru(II) complexes for the applications of potential therapeutics. In order to establish their uses …

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[Pd(Me-Xanthate)_2]: Synthesis, Characterization, And X-Ray Structure, Saira Shahzadi, Saqib Ali, Rehana Jabeen, Muhammad Kaleem Khosa Jan 2009

[Pd(Me-Xanthate)_2]: Synthesis, Characterization, And X-Ray Structure, Saira Shahzadi, Saqib Ali, Rehana Jabeen, Muhammad Kaleem Khosa

Turkish Journal of Chemistry

Potassium methyl xanthate and its complex [Pd(Me-Xanthate)_2] were synthesized at room temperature under stirring conditions. The ligand and the complex were characterized by elemental analysis, IR, NMR (^1H, ^{13}C) and XRD. NMR data revealed that potassium methyl xanthate acts as a bidentate specie and the complex exhibits 4-coordinated geometry in solution. In solid state, the palladium atom is coordinated to the 2 sulfur atoms of the xanthate ligand and the complex exhibits distorted square planar geometry.

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Preparation And Characterization Of 3 Nm Magnetic Niau Nanoparticles, Bethany J. Auten, B. P. Hahn, G. Vijayaraghavan, K. J. Stevenson, Bert D. Chandler Jan 2008

Preparation And Characterization Of 3 Nm Magnetic Niau Nanoparticles, Bethany J. Auten, B. P. Hahn, G. Vijayaraghavan, K. J. Stevenson, Bert D. Chandler

Chemistry Faculty Research

Using PAMAM dendrimers as nanoparticle templates, a synthetic route to prepare 3 nm magnetic NiAu nanoparticles was developed. Aqueous solutions of hydroxyl-terminated generation 5 PAMAM dendrimers in 25 mM NaClO4 were shown to bind aqueous NiII. Coreduction of NiII and AuIII salts yielded bimetallic dendrimer stabilized nanoparticles, which were extracted into toluene with decanethiol. Characterization of the resulting monolayer protected clusters (MPCs) with transmission electron microscopy and UV–visible, atomic absorption, and X-ray photoelectron spectroscopies suggested that the MPCs had substantial surface enrichment in Au. Superconducting quantum interference device (SQUID) measurements at 5 K show the …

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Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans Jan 2008

Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans

Turkish Journal of Chemistry

Trimethyltin(IV) complex containing the carboxylate ligand 2,3-methylenedioxybenzoic acid (HL) have been synthesized and characterized in solution state by multinuclear NMR (^1H, ^{13}C and ^{119}Sn) using the noncoordinating solvent and also in solid sate by FTIR, mass spectrometry, and X-ray crystallography. Spectroscopic data have shown that methylenedioxy moiety has not coordinated with tin atom; instead, the coordination site is a -COO group, which is proved by spectral and XRD data. The solid state structure shows the trigonal bipyramidal geometry with a space group P2_1/c. This compound was tested for its in vitro antitumor activity.

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Characterization And Antimicrobial Activity Of Organotin(Iv) Complexes Of 2-[(2´,6´-Diethylphenylamido)]Benzoates And 3-[(2´,6´-Diethylphenylamido)]Propanoates, Saira Shahzadi, Khadija Shahid, Saqib Ali, Mohammad Bakhtiar Jan 2008

Characterization And Antimicrobial Activity Of Organotin(Iv) Complexes Of 2-[(2´,6´-Diethylphenylamido)]Benzoates And 3-[(2´,6´-Diethylphenylamido)]Propanoates, Saira Shahzadi, Khadija Shahid, Saqib Ali, Mohammad Bakhtiar

Turkish Journal of Chemistry

New organotin(IV) complexes with 2-[(2',6'-diethylphenylamido)] benzoic acid (HL^1) and 3-[(2',6' -diethylphenylamido)]propanoic acid (HL^2) were synthesized by the reaction of di- and triorganotin salts in the presence of triethylamine as base or dioctyltin oxide using a Dean and Stark trap for the removal of azeotropic water. All complexes were characterized by elemental analysis, IR, NMR, and mass spectral studies, and proof that tin-ligand coordination involves only the carboxylate group and complexes show hexa-coordinated geometry in solid state. Multinuclear NMR data show that triorganotin complexes exhibit 4-coordinated geometry while diorganotin complexes show a coordination number greater than 4, probably 5 or 6 …

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Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant Jan 2008

Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

To determine chromophoric dissolved organic matter (CDOM) sources in Southern California coastal waters, optical properties of a river outlet and adjacent tidally flushed salt marshes were monitored (dry season; June July 2001). Average absorption coefficients doubled at ebb vs. flood tides (4.8 +/- 1.5 vs. 2.1 +/- 0.9 m(-1); 300 nm), suggesting significant salt marsh CDOM inputs into coastal waters. Average spectral slopes were not statistically different for any sites or tides (0.010 +/- 0.002 nm(-1)), consistent with salt marsh CDOM dominating coastal waters. Three-dimensional fluorescence excitation-emission matrices (EEMs) at ebb tide showed contributions from terrestrial, protein, and marine humic-like …

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Voltammetric And Spectroscopic Studies Of Vanadium(V)-- Nicotinamide Interactions At Physiological Ph, Semi̇ha Çakir, Ender Bi̇çer Jan 2007

Voltammetric And Spectroscopic Studies Of Vanadium(V)-- Nicotinamide Interactions At Physiological Ph, Semi̇ha Çakir, Ender Bi̇çer

Turkish Journal of Chemistry

The interaction of nicotinamide (NA) with NH_4VO_3 at the physiological pH (pH 7.4) was studied by voltammetry and UV-Vis spectroscopy. The reduction of V(V) ions complexed with NA in phosphate buffer (pH 7.4) was observed as a well-defined reversible reduction peak at --0.35 V. The stoichiometric (metal:ligand) ratio of the complex of V(V) with NA was determined as 1:2 by the mole ratio method.

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Properties Of New York/New Jersey Harbor Sediments, K. W. Jones, Huan Feng, E. A. Stren, U. Neuhäusler, J. Osán, N. Marinkovic, Z. Song Jan 2006

Properties Of New York/New Jersey Harbor Sediments, K. W. Jones, Huan Feng, E. A. Stren, U. Neuhäusler, J. Osán, N. Marinkovic, Z. Song

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Sediments found in waterways around the world may contain toxic compounds of anthropogeilic origin that can harm the environment and human health. As a result, it is often necessary to remove them and find disposal methods that are environmentally and economically acceptable. Here, we report on results obtained in an experimental program to characterize the nature of the sediment contamination. The objective was to gain a better understanding of the properties of the sediments to develop better methods for understanding the fate and transport of the contaminants and for improving methods for their removal from the sediments. Our investigations made …

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Synthesis, Spectroscopic (Ft-Ir, ^1h, ^{13}C, Mass Spectrometry), And Biological Investigation Of Five-Coordinated Germanium-Substituted Tricyclohexyl Antimony Dipropionates: Crystal Structure Of Tricyclohexylantimony Dibromide, Muhammad Kaleem Khosa, Muhammad Mazhar, Saqib Ali, Kieran C. Molloy, Sarim Dastgir, Farkhanda Shaheen Jan 2006

Synthesis, Spectroscopic (Ft-Ir, ^1h, ^{13}C, Mass Spectrometry), And Biological Investigation Of Five-Coordinated Germanium-Substituted Tricyclohexyl Antimony Dipropionates: Crystal Structure Of Tricyclohexylantimony Dibromide, Muhammad Kaleem Khosa, Muhammad Mazhar, Saqib Ali, Kieran C. Molloy, Sarim Dastgir, Farkhanda Shaheen

Turkish Journal of Chemistry

A series of five-coordinated germanium-substituted tricyclohexylantimony dipropionates have been synthesized and characterized by different instrumental techniques, such as elemental analyses, FT-IR, multinuclear NMR (^1H, ^{13}C) and mass spectrometry. These compounds have also been screened against different microbes and they showed good activity against different bacteria that was comparable to the reference drugs. The crystal structure of the precursor (C_6H_{11})_3SbBr_2 is reported here, which showed that the antimony atom in an asymmetric unit exists in trigonal bipyramidal geometry, having space group C2/c with the monoclinic crystal system.

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Fourier Transform Infrared Analysis Of Hydroxyl Content Of Hydrothermally Processed Heteroepitaxial Barium Titanate Films, Sandeep K. Patil, Nipun Shah, Frank D. Blum, M. N. Rahaman Jan 2005

Fourier Transform Infrared Analysis Of Hydroxyl Content Of Hydrothermally Processed Heteroepitaxial Barium Titanate Films, Sandeep K. Patil, Nipun Shah, Frank D. Blum, M. N. Rahaman

Chemistry Faculty Research & Creative Works

The concentration of hydroxyl (-OH) groups in epitaxial barium titanate (BaTiO3) films (thickness ≈ 200 nm), deposited on single-crystal strontium titanate (SrTiO3) at 150 °C by a hydrothermal technique, was investigated using x-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After hydrothermal treatment, a broad FTIR resonance for the hydroxyl groups indicated a significant concentration of surface -OH groups in the films. The as-deposited films were subsequently treated hydrothermally with D2O, and the kinetics of the exchange reaction between -OH incorporated into the film and -OD from the D2O were studied using FTIR. For reactions carried out intermittently, the …

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Synthesis And Characterization Of Dendrimer Templated Supported Bimetallic Pt-Au Nanoparticles, Huifang Lang, S. Maldonado, K. J. Stevenson, Bert D. Chandler Sep 2004

Synthesis And Characterization Of Dendrimer Templated Supported Bimetallic Pt-Au Nanoparticles, Huifang Lang, S. Maldonado, K. J. Stevenson, Bert D. Chandler

Chemistry Faculty Research

Bimetallic dendrimer-stabilized nanoparticles (DSNs) were used to prepare supported Pt-Au catalysts within the bulk miscibility gap for this binary system. Hydroxy-terminated generation 5 PAMAM dendrimers were used to prepare Cu0 nanoparticles (NPs). The Cu0 NPs were subsequently used to reduce K2PtCl4 and HAuCl4, preparing stabilized bimetallic Pt-Au NPs with a 1:1 stoichiometry. The stabilized NPs were adsorbed onto a high surface area silica support and thermally activated to remove the dendrimers. Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and infrared spectroscopy of adsorbed CO showed that this preparation route resulted in NPs in …

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Synthesis, Characterization, And Application Of Water-Soluble Chiral Calix[4]Arene Derivatives In Spectroscopy And Capillary Electrokinetic Chromatography, Kim Hamilton Jan 2003

Synthesis, Characterization, And Application Of Water-Soluble Chiral Calix[4]Arene Derivatives In Spectroscopy And Capillary Electrokinetic Chromatography, Kim Hamilton

LSU Doctoral Dissertations

This dissertation is an account of the synthesis, characterization, and application of novel water-soluble chiral calixarenes in spectroscopy and capillary electrophoresis. It is divided into four sections. The first part describes the synthesis and nuclear magnetic resonance (NMR) characterization of four p-t-butylcalix[4]arenes bearing L-amino acid moieties on their lower rims (CX4-AA). The structure and conformation of the derivatives have been determined using one- and two-dimensional NMR techniques. Proton and carbon-13 spectra show that the derivatives are tetra-substituted and adopt a cone conformation. The preparation and characterization of silica-bonded calixarene stationary phases for capillary electrochromatography is also reported in Chapter 2. …

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Polarized Neutron Diffraction And Mössbauer Spectral Study Of Short-Range Magnetic Correlations In The Ferrimagnetic Layered Compounds (Pph₄) [FeIiFeIii(Ox)₃] And (Nbu₄) [FeIiFeIii(Ox)₃], Simon G. Carling, Dirk W. Visser, Dimitri Hautot, Ian D. Watts, Peter Day, Jürgen Ensling, Phillip Gütlich, Gary J. Long, Fernande Grandjean Sep 2002

Polarized Neutron Diffraction And Mössbauer Spectral Study Of Short-Range Magnetic Correlations In The Ferrimagnetic Layered Compounds (Pph₄) [FeIiFeIii(Ox)₃] And (Nbu₄) [FeIiFeIii(Ox)₃], Simon G. Carling, Dirk W. Visser, Dimitri Hautot, Ian D. Watts, Peter Day, Jürgen Ensling, Phillip Gütlich, Gary J. Long, Fernande Grandjean

Chemistry Faculty Research & Creative Works

Short-range antiferromagnetic correlations have been studied in the layered compounds (PPh4) [FeIIFeIII(ox)3] and (NBu4) [FeIIFeIII(ox)3] by neutron polarization analysis and Mössbauer spectroscopy. Polarized neutron diffraction profiles obtained between 2 and 50 K on (d20-Pph4) [FeIIFeIII(ox)3] show no magnetic Bragg scattering; the lack of such scattering indicates the absence of long-range magnetic order. However, a broad asymmetric feature observed at a Q of ca. 0.8 Å-1 is attributed to two-dimensional short-range magnetic correlations, which …

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Chemical Analysis By X-Ray Spectroscopy Near Phase Transitions In The Solid State, Juana Vivó Acrivos, L. Nguyen, T. Norman, C. T. Lin, W. Y. Liang, J. M. Honig, P Somasundaran Jan 2002

Chemical Analysis By X-Ray Spectroscopy Near Phase Transitions In The Solid State, Juana Vivó Acrivos, L. Nguyen, T. Norman, C. T. Lin, W. Y. Liang, J. M. Honig, P Somasundaran

Faculty Publications, Chemistry

The methods discussed in this work show that the types of changes which may be observed, by precise XAS measurements of Absorbance A versus temperature, across a phase transition are: the changes in the relaxation time of the final states  due to fluctuations near a phase transition; the detection of the anomalous Bragg condition coupled to phonon modes XAS enhancement that identifies the temperature interval where the phonon modes are active, the symmetry changes which introduce new allowed transitions to finite states below an element edge, near Tc indicate what symmetry changes occur, and the method of XTDAFST0 = …

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An Assessment Of The Accuracy Of Semi-Empirical Quantum Chemistry Calculations Of The Mechanical Properties Of Polymers, James R. Shoemaker Mar 1991

An Assessment Of The Accuracy Of Semi-Empirical Quantum Chemistry Calculations Of The Mechanical Properties Of Polymers, James R. Shoemaker

Theses and Dissertations

The ultimate mechanical properties of polymers, assuming perfect morphology, will be limited by the mechanical properties of a single, ideal polymer chain. Previous calculations of polymer chain moduli using semi- empirical (SE) quantum chemistry methods have resulted in modulus values much higher than experimentally measured. This study investigated the error in the calculated inherent to the method of calculation by comparing SE results for C-C bond potentials in two well characterized polymers, polyethylene and polydiacetylene. It was found that the SE calculation systematically overpredicted bond stiffness in these polymers by approximately 25% to 30%. This is the upper limit on …

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Characterization Of Glycated Proteins By 13C Nmr Spectroscopy, Carolyn I. Neglia, Helga J. Cohen, Albert R. Garber, Suzanne R. Thorpe, John W. Baynes Sep 1984

Characterization Of Glycated Proteins By 13C Nmr Spectroscopy, Carolyn I. Neglia, Helga J. Cohen, Albert R. Garber, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

13C NMR spectroscopy has been used to characterize Amadori (ketoamine) adducts formed by reaction of [2-13C]glucose with free amino groups of protein. The spectra of glycated proteins were acquired in phosphate buffer at pH 7.4 and were interpreted by reference to the spectra of model compounds, N alpha-formyl-N epsilon-fructose-lysine and glycated poly-L-lysine (GlcPLL). The anomeric carbon region of the spectrum (approximately 90-105 ppm) of glycated cytochrome c was superimposable on that of N alpha-formyl-N epsilon-fructose-lysine, and contained three peaks characteristic of the alpha- and beta-furanose and beta-pyranose anomers of Amadori adducts to peripheral lysine residues on protein (pK alpha approximately …

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Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia Jan 1981

Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia

Faculty Publications, Chemistry

No abstract provided.

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