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Chemistry

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Missouri University of Science and Technology

1997

Articles 1 - 17 of 17

Full-Text Articles in Physical Sciences and Mathematics

Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann Dec 1997

Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann

Physics Faculty Research & Creative Works

Microphysical properties of jet exhaust aerosol and contrails were studied in the near field of the emitting aircraft for different fuel sulfur contents. Measurements were performed behind two different aircraft (ATTAS test aircraft of type VFW 614 and Airbus A310-300) using fuels with sulfur contents of 6 ppm and 2700 ppm, respectively. At closest approach (plume age < 1 s), the total number concentrations exceeded the measuring range of the condensation particle counter, i.e., N > 105 cm-3. The concentration of the dry accumulation mode aerosol, i.e., predominantly soot particles, was not affected by the fuel sulfur content. At a plume age of 10 s, an increase in total number concentration (Dp > 0.01 μm) by a …

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Temperature-Dependence Studies Of Photorefractive Effect In A Low Glass-Transition-Temperature Polymer Composite, Bogdan Swedek, Ning Cheng, Yiping Cui, Jaroslaw W. Zieba, Jeffrey G. Winiarz, Paras N. Prasad Dec 1997

Temperature-Dependence Studies Of Photorefractive Effect In A Low Glass-Transition-Temperature Polymer Composite, Bogdan Swedek, Ning Cheng, Yiping Cui, Jaroslaw W. Zieba, Jeffrey G. Winiarz, Paras N. Prasad

Chemistry Faculty Research & Creative Works

The temperature dependence of the photorefractive effect in a polymer composite containing poly(9-vinycarbazole), tricresyl phosphate, buckminsterfullerene, and 4-(N,N-diethylamino)-β-nitrostyrene is presented. The photoconductive, electro-optic and photorefractive properties of the material have been studied in the temperature range of 22-61°C. An apparent increase of electro-optic modulation with temperature and its eventual saturation is observed. This behavior is attributed to the temperature activated orientational mobility of the second-order nonlinear chromophores. The polarization anisotropy between the p- and s-polarized readouts is consistent with what would be expected on the basis of directly measured effective electro-optic coefficients. By correlating the electro-optic value with the diffraction …

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Scanning Probe Nanolithography Of Conducting Metal Oxides, Chen-Jen Hung, Jianian Gui, Jay A. Switzer Sep 1997

Scanning Probe Nanolithography Of Conducting Metal Oxides, Chen-Jen Hung, Jianian Gui, Jay A. Switzer

Chemistry Faculty Research & Creative Works

The scanning tunneling microscope (STM) was used to form nanometer-size holes in thin conducting films of thallium (III) oxide. Hole formation was only observed when the process was performed in humid ambient conditions. The hole formation was attributed to localized electrochemical etching reactions beneath the STM tip. etching reactions consistent with the observed hole formation are a direct electrochemical reduction of thallium (III) oxide to soluble T1 (I) at negative sample bias, and local reduction of pH at positive sample bias. The fastest etching was observed at negative sample bias. Holes as small as 10 nm or as large as …

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Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr Sep 1997

Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr

Materials Science and Engineering Faculty Research & Creative Works

Glass ribbon-reinforced transparent polymer composites which provide excellent optical transparency and a low distortion level over a wide temperature range while exhibiting superior mechanical properties as compared to non- reinforced polymer counterparts, and equivalent properties as compared to glass fiber-reinforced counterparts.

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X-Ray-Absorption Spectral Study Of The R₂Fe₁₇₋ₓmₓ Solid Solutions (R=Ce, Nd And M=Al, Si), Denis Vandormael, Fernande Grandjean, Valérie Briois, D. P. Middleton, K. H. Buschow, Gary J. Long Sep 1997

X-Ray-Absorption Spectral Study Of The R₂Fe₁₇₋ₓmₓ Solid Solutions (R=Ce, Nd And M=Al, Si), Denis Vandormael, Fernande Grandjean, Valérie Briois, D. P. Middleton, K. H. Buschow, Gary J. Long

Chemistry Faculty Research & Creative Works

The x-ray-absorption near-edge structure (XANES) spectra obtained at the cerium LIII edge of the Ce2Fe17-xAlx solid solutions and Ce2Fe14Si3, show two absorption peaks characteristic of the 4f1 and 4f0 configurations of cerium, peaks which indicate that cerium is in a mixed valent state in these compounds. All the XANES spectra have been consistently and excellently fit with one sigmoidal function and two Gaussianbroadened Lorentzian functions. The cerium spectroscopic valence obtained from the relative areas of the two peaks decreases from 3.64 to 3.43 between x=0 and …

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Stereoselective Adsorptive Bubble Process, Daniel W. Armstrong, Yubing Tang May 1997

Stereoselective Adsorptive Bubble Process, Daniel W. Armstrong, Yubing Tang

Chemistry Faculty Research & Creative Works

Process for enriching the concentration of an enantiomer (or a diastereomer) in a mixture of optically active isomers. The process includes preparing a solution containing the mixture of the optically active isomers and a chiral collector in which the chiral collector and the enantiomer (or diastereomer) are associated with each other. A gas is bubbled through a pool of the solution to form a foam, the surfaces of the bubbles in the foam having the chiral collector and the enantiomer (or diastereomer) preferentially adsorbed thereto so that the concentration ratio of the optically active isomers at said bubble surfaces differs …

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Xenon Isotope Record Of Nucleosynthesis And The Early Solar System, Jauh-Tzuoh Lee, Bin Li, Oliver Manuel May 1997

Xenon Isotope Record Of Nucleosynthesis And The Early Solar System, Jauh-Tzuoh Lee, Bin Li, Oliver Manuel

Chemistry Faculty Research & Creative Works

No abstract provided.

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In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez May 1997

In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez

Physics Faculty Research & Creative Works

Focussed aircraft measurements have been carried out over the eastern North Atlantic to search for signals of air traffic emissions in the flight corridor region. Observations include NO, NO2, HNO3, SO2, O3, H2O, total condensation nuclei (CN), and meteorological parameters. A flight pattern with constant-altitude north-south legs across the major North Atlantic air traffic tracks was flown. Signatures of air traffic emissions were clearly detected for NOx, SO2, and CN with peak concentrations of 2 ppbv, 0.25 ppbv, and 500 cm-3, respectively, exceeding background …

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Magnetic And Structural Properties Of Nd₂Fe₁₇₋ₓmnₓ Solid Solutions, Peter C. Ezekwenna, G. K. Marasinghe, William Joseph James, Oran Allan Pringle, Gary J. Long, H. Luo, Z. Hu, William B. Yelon, Ph. I'Héritier Apr 1997

Magnetic And Structural Properties Of Nd₂Fe₁₇₋ₓmnₓ Solid Solutions, Peter C. Ezekwenna, G. K. Marasinghe, William Joseph James, Oran Allan Pringle, Gary J. Long, H. Luo, Z. Hu, William B. Yelon, Ph. I'Héritier

Chemistry Faculty Research & Creative Works

A series of Nd2Fe17-xMnx solid solutions with x values between 0 and and 6 were prepared and analyzed using magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. All of the Nd2Fe17-xMnx samples crystallized in the Th2Zn17-x-type rhombohedral structure. The lattice parameters and unit cell volumes decrease with increasing manganese content up to ∼ x equal to 2, and then increase for higher manganese content. The magnetizations of Nd2Fe17-xMnx decrease with increasing manganese content and Nd2Fe17-xMnx is paramagnetic …

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Studies Of V, Nb, Cr, And Zr Substituted 2:17 Compounds And Their Carbides Using Neutron Diffraction, H. Luo, Z. Hu, Muguo Chen, William B. Yelon, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, W. C. Chang, S. H. Tsai Apr 1997

Studies Of V, Nb, Cr, And Zr Substituted 2:17 Compounds And Their Carbides Using Neutron Diffraction, H. Luo, Z. Hu, Muguo Chen, William B. Yelon, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, W. C. Chang, S. H. Tsai

Physics Faculty Research & Creative Works

Samples of Nd2Fe17-xTxCy with T=V, Nb, Cr, and Zr were prepared by melting of the constituent elements including C and studied by neutron diffraction. Comparing with their uncarbided counterparts, we found that the substituents transfer, more or less, from the 6c site to the 18f and 18h sites with the introduction of C atoms. This behavior appears to relate to the electronegativities between the C atoms and the early transition series elements because the 18f and 18h sites are near neighbors of the interstitial C site. However, the C effects in the V. …

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An Analysis Of Iron-Iron Interatomic Distances In Several Rare Earth Transition Metal Intermetallics, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, Z. Hu, William B. Yelon Apr 1997

An Analysis Of Iron-Iron Interatomic Distances In Several Rare Earth Transition Metal Intermetallics, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, Z. Hu, William B. Yelon

Chemistry Faculty Research & Creative Works

As a part of a systematic study of the dependence of iron-iron exchange interactions on near neighbor iron-iron distances in rare earth transition metal magnetic materials, we have conducted a statistical analysis of interatomic distances in Nd2Fe17, Nd2Fe17N3, and Nd2Fe14B. Results, in general, support the notion that larger near neighbor iron-iron distances promote higher Curie temperatures. In this work, special attention has been paid to the expansion of the Nd2Fe17 lattice due to interstitial nitrogenation and the accompanying increase in the Curie temperature. …

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An Electrical Resistivity Study Of Ce₂Fe₁₆.₈ And The Ce₂Fe₁₇₋ₓalₓ And Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, Denis Vandormael, Fernande Grandjean, Hassan Bougrine, Marcel R. Ausloos, D. P. Middleton, K. H. J. Buschow, Gary J. Long Mar 1997

An Electrical Resistivity Study Of Ce₂Fe₁₆.₈ And The Ce₂Fe₁₇₋ₓalₓ And Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, Denis Vandormael, Fernande Grandjean, Hassan Bougrine, Marcel R. Ausloos, D. P. Middleton, K. H. J. Buschow, Gary J. Long

Chemistry Faculty Research & Creative Works

Electrical resistivity measurements have been carried out between 20 and 300 K on Ce2Fe16.8, on the Ce2Fe17-xAlx. solid solutions, with x = 0.4, 1, 2, 5, 6, 8, and 9, and on the Ce2Fe17-xSix solid solutions, with x = 0.2, 0.4, 1, and 2, with the four probe method. The temperature dependence of the resistivity of Ce2Fe16.8 shows an inflection at 110 K, a feature which is also observed in the temperature dependence of the magnetization and is related to a magnetic …

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Chiral Separation Of Monoterpenes Using Mixtures Of Sulfated Β-Cyclodextrins And Α-Cyclodextrin As Chiral Additives In The Reversed-Polarity Capillary Electrophoresis Mode, Kyung Hyun Gahm, Lisa W. Chang, Daniel W. Armstrong Jan 1997

Chiral Separation Of Monoterpenes Using Mixtures Of Sulfated Β-Cyclodextrins And Α-Cyclodextrin As Chiral Additives In The Reversed-Polarity Capillary Electrophoresis Mode, Kyung Hyun Gahm, Lisa W. Chang, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The use of mixtures of sulfated β-cyclodextrins and native α-cyclodextrin as chiral additives in capillary electrophoresis was evaluated for the chiral resolution of neutral, cyclic and bicyclic monoterpenes, including α-pinene, (β-pinene, camphene and limonene. Binding properties of sulfated β-cyclodextrins towards these monoterpenes were studied. It was found that there was no enantioresolution of these terpenoids over the concentration range studied. However, the addition of α-cyclodextrin to the running electrolyte in addition to 6.5 mM sulfated β-cyclodextrins, imparted differences in the mobilities of the terpenoid enantiomers and resulted in remarkable enantiomeric separations of α-pinene (R(s)=25), β-pinene (R(s)=12), camphene (R(s)=12) and limonene …

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Crystal Structure Of (Μ-Tranis-4,4'-Dinitro-2,2'-Biimidazolato-N,N: N'',N''') Bis[Bis(Triphenylphosphine Copper(I))] N,N-Dimethylformamide, [C42h37cun4o3p2]2, R. G. Baughman, C. A. Hester, Harvest L. Collier Jan 1997

Crystal Structure Of (Μ-Tranis-4,4'-Dinitro-2,2'-Biimidazolato-N,N: N'',N''') Bis[Bis(Triphenylphosphine Copper(I))] N,N-Dimethylformamide, [C42h37cun4o3p2]2, R. G. Baughman, C. A. Hester, Harvest L. Collier

Chemistry Faculty Research & Creative Works

No abstract provided.

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Immunologic And Hematopoietic Effects Of Cd40 Stimulation After Syngeneic Bone Marrow Transplantation In Mice, Satoshi Funakoshi, Dennis D. Taub, Miriam R. Anver, Arati Raziuddin, Osamu Asai, Prakash Reddy, Helen C. Rager, William C. Fanslow, Dan L. Longo, William J. Murphy Jan 1997

Immunologic And Hematopoietic Effects Of Cd40 Stimulation After Syngeneic Bone Marrow Transplantation In Mice, Satoshi Funakoshi, Dennis D. Taub, Miriam R. Anver, Arati Raziuddin, Osamu Asai, Prakash Reddy, Helen C. Rager, William C. Fanslow, Dan L. Longo, William J. Murphy

Chemistry Faculty Research & Creative Works

CD40 is a molecule present on multiple cell types including B lymphocyte lineage cells. CD40 has been shown to play an important role in B cell differentiation and activation in vitro, although little is known concerning the effects of CD40 stimulation in vivo. We therefore examined the effects of CD40 stimulation in mice using a syngeneic bone marrow transplantation (BMT) model in an effort to augment B cell recovery after high dose therapy with hematopoietic reconstitution. After the BMT, mice were treated with or without 2-6 μg of a soluble recombinant murine CD40 ligand (srmCD40L) given intraperitoneally twice a week. …

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Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven Jan 1997

Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven

Physics Faculty Research & Creative Works

Aircraft-based measurements of sulfur dioxide, acetone, carbon dioxide, and condensation nuclei (CN) were made over the north-eastern Atlantic at upper tropospheric altitudes, around 9000 m. On October 14, 1993, strong SO 2- and acetone-pollution (both up to 3 ppbv) were observed, which were accompanied by a CO 2-enhancement of up to 6 ppmv, and large CN-concentrations of up to about 1500 cm -3 (for radii ≥ 6 nm). CN, excess CO 2, and to a lesser degree also acetone, were positively correlated with SO 2. Air mass trajectory analyses indicate, that most of the air masses …

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Varietal Differences In The Total And Enantiomeric Composition Of Theanine In Tea, K. Helen Ekborg-Ott, Andre Taylor, Daniel W. Armstrong Jan 1997

Varietal Differences In The Total And Enantiomeric Composition Of Theanine In Tea, K. Helen Ekborg-Ott, Andre Taylor, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Theanine is the main amino acid component in tea. It usually constitutes between 1 and 2% of the dry weight of the tea leaves. It is as prevalent in tea as all other free amino acids combined. Both enantiomers of theanine were found to have a similar sweet taste, with little or no aftertaste. It was found that black and half-green teas (except for Formosa Oolong) contained as much, or more, theanine as green teas. No correlation was found between the absolute concentration of theanine in tea and its enantiomeric composition. An inverse correlation was found between certain grades of …

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