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Articles 29491 - 29520 of 34578

Full-Text Articles in Physical Sciences and Mathematics

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, J. Paladino, Max B. Trueblood, H. Lilenfeld May 1998

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, J. Paladino, Max B. Trueblood, H. Lilenfeld

Physics Faculty Research & Creative Works

Particle size and emission indices measurements for jet engines, primarily the Rolls Royce RB211 engines on a NASA 757 aircraft are reported. These data were used to estimate the fraction of fuel sulfur that was converted to particulates. These measurements were made in-situ with the sampling aircraft several kilometers behind the source. Some complimentary ground measurements on the same source aircraft and engines are also reported. Significant differences are seen between the ground observations and the in-situ observations, indicating that plume processes are changing the aerosol' s characteristics.

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A Comparison Between The Cisd[Tq] Wave Function And Other Highly Correlated Methods: Molecular Geometry And Harmonic Vibrational Frequencies Of Mgh2, Gregory S. Tschumper, Henry F. Schaefer May 1998

A Comparison Between The Cisd[Tq] Wave Function And Other Highly Correlated Methods: Molecular Geometry And Harmonic Vibrational Frequencies Of Mgh2, Gregory S. Tschumper, Henry F. Schaefer

Chemistry Faculty Research & Creative Works

The linear MgH2 molecule was selected as a model system to compare the total electronic energy (ETOT). equilibrium bond length (re), and vibrational frequency (ωn) predictions from six different configuration interaction (CI) and coupled cluster (CC) methods using three large correlation consistent basis sets. The three CI procedures employed incorporated all single and double substitutions (CISD) as well as all triple and quadruple substitutions (CISDTQ) or limited triple and quadruple substitutions (CISD[TQ]). The remaining three CC schemes included all single and double excitations (CCSD) as well as all triple excitations (CCSDT) or a perturbative approximation of the triple excitations [CCSD(T)]. …

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Molecular Design And Association Constants Of Nizatidine-Guest Complexes, Elizabeth Corbeil May 1998

Molecular Design And Association Constants Of Nizatidine-Guest Complexes, Elizabeth Corbeil

Honors Theses

Nizatidine, N-[2-[[[2-[(dimethylamino)metbyl]-4-thiazolyl]methyl]thio]ethyl]-N'methyl- 2-nitro-l,l-ethenediamine (Axid"), has been investigated for its potential to act as a host in guest-host complexes. Nizatidine binds with the guests through hydrogen bonding and pi-pi interactions. Guest-host studies were conducted using fluorescence quenching, calorimetry, NMR and invisible experiments. The lowest energy conformation of nizatidine is found to be U-shaped through theoretical calculations. Fluorescence experiments indicated that tryptophan and pyridoxine had large association constants. Further studies using calorimetry and NMR techniques concluded that no complexation had occurred. Complexation experiments have been done to find guests that complex with nizatidine. Caffeine, luminol, nicotinamide, phenylalanine, pyridoxine, pyrogallol, and tryptophan were …

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Isolation And Structure Of Sc2@C74, Harry Dorn, Steven Stevenson, Paul Burbank, Kim Harich, Z. Sun, T. Glass, Mark Anderson, Donald Bethune, M. Sherwood May 1998

Isolation And Structure Of Sc2@C74, Harry Dorn, Steven Stevenson, Paul Burbank, Kim Harich, Z. Sun, T. Glass, Mark Anderson, Donald Bethune, M. Sherwood

Mark R. Anderson

No abstract is currently available.

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29. Motowo Takayanagi, Otto Vogl, Tisoro Kajiyama May 1998

29. Motowo Takayanagi, Otto Vogl, Tisoro Kajiyama

Otto Vogl

No abstract provided.

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Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, Jonathan D. Paladino, Max B. Trueblood May 1998

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, Jonathan D. Paladino, Max B. Trueblood

Physics Faculty Research & Creative Works

Particle size and emission indices measurements for jet engines, primarily the Rolls Royce RB211 engines on a NASA 757 aircraft are reported. These data were used to estimate the fraction of fuel sulfur that was converted to particulates. These measurements were made in-situ with the sampling aircraft several kilometers behind the source. Some complimentary ground measurements on the same source aircraft and engines are also reported. Significant differences are seen between the ground observations and the in-situ observations, indicating that plume processes are changing the aerosol's characteristics.

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Particle Concentration Characterization For Jet Engine Emissions Under Cruise Conditions, Jonathan D. Paladino, Philip D. Whitefield, Donald E. Hagen, Alfred R. Hopkins, Max B. Trueblood May 1998

Particle Concentration Characterization For Jet Engine Emissions Under Cruise Conditions, Jonathan D. Paladino, Philip D. Whitefield, Donald E. Hagen, Alfred R. Hopkins, Max B. Trueblood

Chemistry Faculty Research & Creative Works

Airborne particle measurements during NASA project SUCCESS have shown that particle concentration profiles serve as good indicators of aircraft exhaust plume encounters. During exhaust plume penetrations there is a strong anticorrelation between the ratio of nonvolatile/total particulates and Nitrogen Oxide (NO) concentrations. an increase in fuel sulfur content was found to increase the total particle emission index, while the nonvolatile emission index remained unchanged. the EI's increased by a factor of 2.6 as the fuel sulfur increased from 70 - 700 ppm. the large particle size distribution (200-400 nm) was seen as a good long term indicator of an aircraft …

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Determination Of Intracellular Glutathione Concentration Using Monobromobimane, Ryan R. Owens May 1998

Determination Of Intracellular Glutathione Concentration Using Monobromobimane, Ryan R. Owens

Undergraduate Honors Capstone Projects

Asbestos is a general term for a group of fibrous silicates. Diseases such as asbestosis, bronchogenic carcinoma, and mesothelioma have been linked to asbestos exposure (1,2). The 1 two classes of asbestos, serpentine and amphibole, are distinguished by differences in structure and chemical composition (3). The amphibole crocidolite contains 27% iron while the serpentine chrysotile contains only 2-3% iron. The higher iron content of crocidolite is proposed to be a contributing factor for a much higher incidence of cancer with crocidolite exposure compared with chrysotile exposure ( 4). Iron mobilized intracellularly from asbestos fibers may participate in the formation of …

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Plant-Availability Fractionation Of Nickel For Bioremediation, Jason Henrie May 1998

Plant-Availability Fractionation Of Nickel For Bioremediation, Jason Henrie

Undergraduate Honors Capstone Projects

The bioremediation of contaminated soils or the biomining of waste tillings has been explored through the use of hyperaccumulating plants such as S. polygaloides which is a nickel hyperaccumulator. However, it is important to discover which soils are well-suited for this type of process by determining the plant-availability of the nickel. By extracting the nickel sequentially with increasing severity it is possible to determine the chemical distribution, or fractionation, of nickel in a soil. One fraction is already suspected to be plant-available and correlates very well with the results of a previous plant-availability study. A calcareous Millville silt loam which …

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Thermal Decomposition Of Cp*Re(Co)(No)No2, Kale Allen Swainston May 1998

Thermal Decomposition Of Cp*Re(Co)(No)No2, Kale Allen Swainston

Undergraduate Honors Capstone Projects

The focus of this work is to examine the thermal reactivity of the Cp*Re(CO)(NO)NO2 complex. Upon heating with a flame, the orange crystals decompose very rapidly, with a darkening of color and gas production. To investigate this reaction, the decomposition was carefully controlled by heating with N2 gas, and in heated solution. The products obtained from the heated solution were purified using column chromatography, yielding two new interesting compounds, believed to be Cp*ReNO dimers with bridging oxygens.

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Site-Directed Mutagenesis Of The Nitrogenase Fe-Protein From Azotobacter Vinelandii, Talmage L. Shill May 1998

Site-Directed Mutagenesis Of The Nitrogenase Fe-Protein From Azotobacter Vinelandii, Talmage L. Shill

Undergraduate Honors Capstone Projects

Nitrogen fixation is the chemical reaction of dinitrogen (N2) being reduced to ammonia (NH3). This reaction occurs naturally by nitrogen fixing microorganisms which contain the enzyme nitrogenase. The overall reaction is written below.

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Quantitative And Stereoisomeric Determination Of Light Biomarkers In Crude Oil And Coal Samples, Alain Berthod, Xiande Wang, Kyung H. Gahm, Daniel W. Armstrong May 1998

Quantitative And Stereoisomeric Determination Of Light Biomarkers In Crude Oil And Coal Samples, Alain Berthod, Xiande Wang, Kyung H. Gahm, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Indans and tetralins are considered biological markers (biomarkers). These C9-C11 hydrocarbons are present in small amounts in organic geological samples. Methyl substituted indans or tetralins may possess a stereogenic center (carbon). Thus they can exist as enantiomers and, in the case of disubstituted enties, also as diastereoisomers. The concentrations of 1-methylindan, 1,3-dimethylindan, 1-methyltetralin, and 2-methyltetralin were determined in 16 crude oil samples of different sources and in 14 coal samples of different sources and ranks. Deuterated homologues were synthesized as standards to spike the samples and to assure accurate quantitative analysis. A procedure using HPLC fractionation followed by GC/MS analysis …

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Mössbauer-Effect And X-Ray-Absorption Spectral Study Of Sonochemically Prepared Amorphous Iron, Gary J. Long, Dimitri Hautot, Quentin A. Pankhurst, Denis Vandormael, Fernande Grandjean, Jean Pierre Gaspard, Valérie Briois, Taeghwan Hyeon, Kenneth S. Suslick May 1998

Mössbauer-Effect And X-Ray-Absorption Spectral Study Of Sonochemically Prepared Amorphous Iron, Gary J. Long, Dimitri Hautot, Quentin A. Pankhurst, Denis Vandormael, Fernande Grandjean, Jean Pierre Gaspard, Valérie Briois, Taeghwan Hyeon, Kenneth S. Suslick

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of amorphous iron, prepared by using sonochemical methods, exhibit a broad magnetic hyperfine sextet at both 78 and 295 K. The spectra do not change with time if the amorphous iron is not exposed to oxygen or moisture. An analysis of the spectra with the method of Lines and Eibschütz yields average magnetic hyperfine fields of 29.1 and 25.9 T at 78 and 295 K, respectively. The corresponding moments of 1.9B and 1.7B agree well with values obtained from earlier magnetization studies and, further, provide strong experimental support for earlier calculations of the magnetic moments …

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Structure Of 5-Nitro-2-Tosylaminobenzaldehyde Di(Morpholin-4-Yl)Aminal Complex With Carbon Tetrachloride, V. N. Khrustalev, Sergey V. Lindeman, L. Yu Ukhin, G. I. Orlova, T. N. Gribanova, O. V. Shishkin May 1998

Structure Of 5-Nitro-2-Tosylaminobenzaldehyde Di(Morpholin-4-Yl)Aminal Complex With Carbon Tetrachloride, V. N. Khrustalev, Sergey V. Lindeman, L. Yu Ukhin, G. I. Orlova, T. N. Gribanova, O. V. Shishkin

Chemistry Faculty Research and Publications

The 5-nitro-2-tosylaminobenzaldehyde di(morpholin-4-yl)aminal forms a stable complex with carbon tetrachloride in the crystal phase. X-ray structural study of this complex indicates an essentially shortened intermolecular contact of 2.89 Å between the oxygen atom of the nitro group and one of the chlorine atom of the CCI4 molecule. Quantum-chemical calculations by semiempirical AMI method showed that the formation of such complex did not cause considerable decrease of system energy or change of charge distribution in molecules. It was supposed that this associate has van der Waals character.

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A Method For The Determination Of Purity Of Pnu-10483 Bulk Drug By Capillary Zone Electrophoresis, Gavin Gibson Apr 1998

A Method For The Determination Of Purity Of Pnu-10483 Bulk Drug By Capillary Zone Electrophoresis, Gavin Gibson

Honors Theses

In this investigation, a method was developed for the determination of purity of the drug PNU-10483 using the technique of capillary zone electrophoresis (CZE). CZE was seen as a potential alternative to the formerly used procedure of ion-pair reversed phase highperformance liquid chromatography (HPLC). Nearly five years earlier, a similar study was performed, in which an attempt was made to develop a method that used CZE to determine the purity of bulk drug and the potency of drug tablets. While this development was mostly successful, sporadically unpredictable results reduced the method's overall viability. These outliers were thought to be caused …

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Spectroscopic Probes Of Bonded Interfaces, Mark Anderson, C. Douglas Taylor, Cynthia Kraft Apr 1998

Spectroscopic Probes Of Bonded Interfaces, Mark Anderson, C. Douglas Taylor, Cynthia Kraft

Mark R. Anderson

No abstract is currently available.

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The Electrochemistry Of Fullerenes And Metallofullerenes, Mark Anderson Apr 1998

The Electrochemistry Of Fullerenes And Metallofullerenes, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

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Studies Of Molecular Priming For Adhesive Interactions, C, Douglas Taylor, Mark Anderson Apr 1998

Studies Of Molecular Priming For Adhesive Interactions, C, Douglas Taylor, Mark Anderson

Mark R. Anderson

No abstract is currently available.

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Quadratic Electro-Optic Effects In Bacteriorhodopsin: Measurement Of Γ(-Ω;0,0,Ω) In Dried Gelatin Thin Films, Mikio Yamazaki, Jerry Goodisman, Robert R. Birge Apr 1998

Quadratic Electro-Optic Effects In Bacteriorhodopsin: Measurement Of Γ(-Ω;0,0,Ω) In Dried Gelatin Thin Films, Mikio Yamazaki, Jerry Goodisman, Robert R. Birge

Chemistry - All Scholarship

Quadratic electro-optic effects (dc or low frequency Kerr effect) of bacteriorhodopsin dispersed in dried gelatin thin films are examined in the near resonance region at three wavelengths: 633, 647, and 676 nm. The films show relatively large quadratic electro-optic effects compared to other molecular dispersed systems. The purple membrane is fixed within the polymerized gelatin matrix, and we show that the electronic contribution to γ dominates over possible orientational contributions. At 676 nm. the quadratic electro-optic coefficient s1133( - ω;0,0,ω) is 6.7 × 10-20 m2/V2 and the third order nonlinear susceptibility X1133(3) …

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30. Manfred Raetzsch, Otto Vogl Apr 1998

30. Manfred Raetzsch, Otto Vogl

Otto Vogl

No abstract provided.

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Neutral Dissociation Of Hydrogen Following Photoexcitation Of Hcl At The Chlorine K Edge, D. L. Hansen, J. Cotter, G. R. Fisher, K. T. Leung, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield Apr 1998

Neutral Dissociation Of Hydrogen Following Photoexcitation Of Hcl At The Chlorine K Edge, D. L. Hansen, J. Cotter, G. R. Fisher, K. T. Leung, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield

Chemistry and Biochemistry Faculty Research

Time-of-flight mass spectroscopy was used to study the relaxation dynamics of HCl following photoexcitation in the vicinity of the Cl K edge (~2.8 keV) using monochromatic synchrotron radiation. At the lowest resonant excitation to the 6ơ* antibonding orbital, almost half of the excited molecules decay by emission of a neutral H atom, mostly in coincidence with a highly charged Cln1 ion. The present work demonstrates that neutral-atom emission can be a significant decay channel for excited states with very short lifetimes (1 fs). [S1050-2947(98)03604-X]

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Distance Dependence Of Electron Transfer Along Artificial Beta-Strands At 298 And 77 K, S. R. L. Fernando, Gennady V. Kozlov, Michael Y. Ogawa Apr 1998

Distance Dependence Of Electron Transfer Along Artificial Beta-Strands At 298 And 77 K, S. R. L. Fernando, Gennady V. Kozlov, Michael Y. Ogawa

Chemistry Faculty Publications

Photoinduced electron-transfer rate constants were measured for a series of binuclear metallopeptides consisting of a [Ru(bpy)(2)(cmbpy)](2+) electron donor tethered to a Co-III(NH3)(5) electron acceptor by an oligovaline peptide chain (bpy = 2,2'-bipyridine, cmbpy = 4-carboxy-4'-methyl-2,2'-bipyridine). These compounds were shown by H-1 NMR to adopt the conformational properties found within the individual strands of a beta-pleated sheet in both aqueous and methanol solutions. Emission lifetime measurements and HPLC product analysis show that the binuclear donor/acceptor compounds undergo photoinduced electron transfer (ET). The values of k(et) decrease with increasing donor/acceptor distance according to the expression k(et) = k' exp[-beta(r(-)r(0))]. A distance attenuation …

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Explosive Vapor Generation And Sampling In Conjunction With Ion Mobility Spectrometry, Saeed H. Almeer Apr 1998

Explosive Vapor Generation And Sampling In Conjunction With Ion Mobility Spectrometry, Saeed H. Almeer

Chemistry & Biochemistry Theses & Dissertations

The primary objective of this research is to develop an inexpensive and reliable method to generate vapor pulses of explosives using 2,4,6-trinitrotoluene TNTl for proof of concept. A secondary objective is to demonstrate the use of the vapor generator in various applications keeping in mind potential field scenarios involving explosives. A vapor generator/collector system was developed which gives reproducible pulses of TNT vapors at nanogram levels. The use of this technology was demonstrated in evaluating different surfaces for vapor adsorption of TNT in conjunction with ion mobility spectrometry as the primary analytical tool. Of the materials examined, Teflon was by …

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Sublimation Enthalpies At 298.15 K Using Correlation Gas Chromatography And Differential Scanning Calorimetry Measurements, James Chickos, Donald Hesse, Sarah Hosseini, Gary Nichols, Paul Webb Mar 1998

Sublimation Enthalpies At 298.15 K Using Correlation Gas Chromatography And Differential Scanning Calorimetry Measurements, James Chickos, Donald Hesse, Sarah Hosseini, Gary Nichols, Paul Webb

James Chickos

No abstract provided.

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Synthesis Of Licoo2 Powders For Lithium-Ion Batteries From Precursors Derived By Rotary Evaporation., P. Kumpta, D. Gallet, A. Waghray, G. Blomgren, Michael Setter Mar 1998

Synthesis Of Licoo2 Powders For Lithium-Ion Batteries From Precursors Derived By Rotary Evaporation., P. Kumpta, D. Gallet, A. Waghray, G. Blomgren, Michael Setter

Michael P. Setter

Lithium cobalt oxide (LiCoO2) has received considerable attention in the last few years and is a well-known cathode material for high voltage (4 V) rechargeable Li-ion batteries. A simple chemical approach based on aqueous solution chemistry has been developed to synthesize molecularly mixed amorphous precursors. The precursors begin to transform to form LiCoO2 upon heat treatment at temperatures as low as 400°C. Strong peaks characteristic of the desired high temperature (HT) phase of LiCoO2 evolve when the precursors are heat treated to 800°C for 2 h. The morphology and particle size of the powders have been examined using scanning electron …

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A Cell Cycle-Regulated Adenine Dna Methyltransferase From Caulobacter Crescentus Processively Methylates Gantc Sites On Hemimethylated Dna, Anthony J. Berdis, Irene Lee, James K. Coward, Craig Stephens, Rachel Wright, Lucy Shapiro, Stephen J. Benkovic Mar 1998

A Cell Cycle-Regulated Adenine Dna Methyltransferase From Caulobacter Crescentus Processively Methylates Gantc Sites On Hemimethylated Dna, Anthony J. Berdis, Irene Lee, James K. Coward, Craig Stephens, Rachel Wright, Lucy Shapiro, Stephen J. Benkovic

Chemistry Faculty Publications

The kinetic properties of an adenine DNA methyltransferase involved in cell cycle regulation of Caulobacter crescentus have been elucidated by using defined unmethylated or hemimethylated DNA (DNAHM) substrates. Catalytic efficiency is significantly enhanced with a DNAHM substrate. Biphasic kinetic behavior during methyl incorporation is observed when unmethylated or DNAHM substrates are used, indicating that a step after chemistry limits enzyme turnover and is most likely the release of enzyme from methylated DNA product. The enzyme is thermally inactivated at 30°C within 20 min; this process is substantially decreased in the presence of saturating concentrations of DNAHM, suggesting that the enzyme …

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Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng Mar 1998

Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The contribution of the center-of-mass (CM) fluctuation of a liquid cluster to the Helmholtz free energy was first discussed by Reiss, Katz, and Cohen (RKC). They argued that this contribution can be assessed via the free energy difference between the cluster with a fixed boundary centered on a fixed CM, and the cluster in which the CM was allowed to fluctuate. They estimated the free energy difference is to be about 20 kbT. Here kb is the Boltzmann constant and T is the temperature of the system. To examine this estimate, Abraham et al. later calculated …

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Characterization And Evaluation Of D-(+)-Tubocurarine Chloride As A Chiral Selector For Capillary Electrophoretic Enantioseparations, Usha B. Nair, Daniel W. Armstrong, Willie L. Hinze Mar 1998

Characterization And Evaluation Of D-(+)-Tubocurarine Chloride As A Chiral Selector For Capillary Electrophoretic Enantioseparations, Usha B. Nair, Daniel W. Armstrong, Willie L. Hinze

Chemistry Faculty Research & Creative Works

A new macrocyclic of the bis(benzylisoquinoline) alkaloid family, d- (+)-tubocurarine chloride (DTC), has been evaluated as a chiral selector for the separation of optical isomers of organic carboxylates using capillary electrophoresis (CE). The pertinent physicochemical properties, such as absorption spectrum, isoionic point, and solution conformation, of DTC were determined. The effects of varying such experimental parameters as DTC concentration, pH, and methanol content in the running buffer were assessed. CE separation of the enantiomers of 18 different compounds was achieved using DTC as the chiral selector under optimized background electrolytic conditions.

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The Voltammetry Of C84 Isomers, Mark Anderson, Harry Dorn, Steven Stevenson, Susanne Dana Mar 1998

The Voltammetry Of C84 Isomers, Mark Anderson, Harry Dorn, Steven Stevenson, Susanne Dana

Mark R. Anderson

The square-wave voltammetry of isolated isomers of C84 is reported. Based on their relative abundance, the isomers are assumed to have D2 and D2d symmetry. The D2 isomer has four reversible reductions at −0.65, −0.98, −1.34, and −1.75 V versus Fc/Fc+ prior to electrolyte decomposition. This behavior is consistent with previous reports, and is similar to the voltammetry of C60 and C70 (e.g. sequential reductions spaced at slightly increasing intervals). The D2d isomer has five reversible reductions at −0.46, −0.77, −1.58, −1.98, and −2.27 V versus Fc/Fc+ prior to the onset of electrolyte decomposition. The large potential difference separating the …

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31. Yoshio Iwakura, Otto Vogl, Seiichi Nakahama Mar 1998

31. Yoshio Iwakura, Otto Vogl, Seiichi Nakahama

Otto Vogl

No abstract provided.

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