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1998

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Articles 31 - 60 of 297

Full-Text Articles in Chemistry

Determination Of Chloride Concentration Using Capillary Zone Electrophoresis: An Instrumental Analysis Chemistry Laboratory Experiment, Michael A. Janusa Nov 1998

Determination Of Chloride Concentration Using Capillary Zone Electrophoresis: An Instrumental Analysis Chemistry Laboratory Experiment, Michael A. Janusa

Faculty Publications

Capillary zone electrophoresis (CZE) has received a great deal of attention as a tool for the separation and detection of low-molecular-mass inorganic ions. CZE is a fast growing analytical technique that uses a low-volume sample accompanied by a high detection efficiency. Since this is a fairly new analytical technique that shows tremendous promise, it should be introduced to students at the undergraduate level. We have developed a CZE experiment that is well suited for an instrumental analysis chemistry laboratory and can be modified for other species or substances.

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Dynamics Of Biomolecules: Assignment Of Local Motions By Fluorescence Anisotropy Decay, Carl N. Bialik, Barnabas Wolf, Edward L. Rachofsky, J. B. A. Ross, William Laws Nov 1998

Dynamics Of Biomolecules: Assignment Of Local Motions By Fluorescence Anisotropy Decay, Carl N. Bialik, Barnabas Wolf, Edward L. Rachofsky, J. B. A. Ross, William Laws

Chemistry and Biochemistry Faculty Publications

Many biological systems have multiple fluorophores that experience multiple depolarizing motions, requiring multiple lifetimes and correlation times to define the fluorescence intensity and anisotropy decays, respectively. To simplify analyses, an assumption often made is that all fluorophores experience all depolarizing motions. However, this assumption usually is invalid, because each lifetime is not necessarily associated with each correlation time. To help establish the correct associations and recover accurate kinetic parameters, a general kinetic scheme that can examine all possible associations is presented. Using synthetic data sets, the ability of the scheme to discriminate among all nine association models possible for two …

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Conserved Geometrical Base-Pairing Patterns In Rna, Neocles B. Leontis, Eric Westhof Nov 1998

Conserved Geometrical Base-Pairing Patterns In Rna, Neocles B. Leontis, Eric Westhof

Chemistry Faculty Publications

RNA molecules fold into a bewildering variety of complex 3D structures. Almost every new RNA structure obtained at high resolution reveals new, unanticipated structural motifs, which we are rarely able to predict at the current stage of our theoretical understanding. Even at the most basic level of specific RNA interactions – base-to-base pairing – new interactions continue to be uncovered as new structures appear. Compilations of possible non-canonical base-pairing geometries have been presented in previous reviews and monographs (Saenger, 1984; Tinoco, 1993). In these compilations, the guiding principle applied was the optimization of hydrogen-bonding. All possible pairs with two standard …

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High-Resolution Electron Time-Of-Flight Apparatus For The Soft-X-Ray Region, Oliver Hemmers, S. B. Whitfield, P. Glans, H. Wang, Dennis W. Lindle, R. Wehlitz, I. A. Sellin Nov 1998

High-Resolution Electron Time-Of-Flight Apparatus For The Soft-X-Ray Region, Oliver Hemmers, S. B. Whitfield, P. Glans, H. Wang, Dennis W. Lindle, R. Wehlitz, I. A. Sellin

Environmental Studies Faculty Publications

A gas-phase time-of-flight (TOF) apparatus, capable of supporting as many as six electron-TOF analyzers viewing the same interaction region, has been developed to measure energy- and angle-resolved electrons with kinetic energies up to 5 keV. Each analyzer includes a newly designed lens system that can retard electrons to about 2% of their initial kinetic energy without significant loss of transmission; the analyzers can thus achieve a resolving power (E/ΔE) greater than 104 over a wide kinetic-energy range. Such high resolving power is comparable to the photon energy resolution of state-of-the-art synchrotron–radiation beamlines in the soft …

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Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle Nov 1998

Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle

Environmental Studies Faculty Publications

The relaxation dynamics of HCl, DCl, H2S, and D2S following photoexcitation in the vicinities of the Cl and S K-shell thresholds (∼2.8keV for Cl, ∼2.5 keV for S) were studied by means of ion time-of-flight mass spectroscopy. In all cases, the onset of pre-edge core-shell photoionization precedes the formation on resonance of a significant amount of neutral hydrogen as well as postcollision-interaction effects above threshold. Examination of the width of the H+ peak in spectra taken with the analyzer parallel and perpendicular to the polarization vector of the incident light indicates that on resonance, the …

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Tga–Fti.R. Investigation Of The Thermal Degradation Of Nafion® And Nafion®/[Silicon Oxide]-Based Nanocomposites, Q. Deng, Charles Wilkie, R. B. Moore, Kenneth A. Mauritz Nov 1998

Tga–Fti.R. Investigation Of The Thermal Degradation Of Nafion® And Nafion®/[Silicon Oxide]-Based Nanocomposites, Q. Deng, Charles Wilkie, R. B. Moore, Kenneth A. Mauritz

Chemistry Faculty Research and Publications

The integrated TGA–FTi.r. technique probed the thermal degradation of: (1) a Nafion®–H+ membrane; (2) this membrane as modified by incorporation of a SiO2[1-x/4] (OH)x phase via in situ sol–gel reactions for tetraethoxysilane; and (3) this modified membrane as further modified, organically, via post-reaction with diethoxydimethylsilane. Gravimetric loss is multistep for (1) and (2), but occurs in a single step for (3) which has the greatest thermal degradative stability. The considerable inhibition of SO2 evolution for (2) and (3) is rationalized in terms of side-chains that are immobilized within silicon oxide cages …

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Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan Nov 1998

Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan

Faculty Publications

Canonical Monte Carlo simulations were performed for a nonprimitive model of an electrical double layer. The ions and the solvent molecules are modeled as charged and dipolar hard spheres, respectively, while the electrode as a hard, impenetrable wall carrying uniform surface charge. We found that the ion-dipole model gives a reasonable description of the double layer for partially charged ions with small to moderate dipole moments, or equivalently for an "effective" dielectric constant. Density, polarization and mean electrostatic potential profiles are reported. Strong layering structure, and at higher charges, charge inversion in the second layer were found. With appropriate choices …

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Evaluation Of The Macrocyclic Antibiotic Avoparcin As A New Chiral Selector For Hplc, K. Helen Ekborg-Ott, John P. Kullman, Xiande Wang, Kyung Gahm, Lingfeng He, Daniel W. Armstrong Oct 1998

Evaluation Of The Macrocyclic Antibiotic Avoparcin As A New Chiral Selector For Hplc, K. Helen Ekborg-Ott, John P. Kullman, Xiande Wang, Kyung Gahm, Lingfeng He, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Avoparcin is a macrocyclic glycopeptide antibiotic structurally related to vancomycin, teicoplanin, and ristocetin A. When attached to 5-μm spherical silica gel, the avoparcin proved to be an effective chiral stationary phase (CSP) that could be used in the reversed-phase, normal- phase, and polar-organic modes. The avoparcin CSP was complimentary to the other macrocyclic glycopeptide CSPs in that it could resolve some racemates that the others could not, and vice versa. Some important compounds resolved on the avoparcin CSP include verapamil, thyroxine, mephenytoin, and 2- imidazolidone-4-carboxylic acid. The use of this CSP and the optimization of separations on it are discussed. …

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Influence Of 5'-(Tg)1-3- And 3'-(Ac)1-3-Overhangs On The Thermodynamic And Na+ Binding Properties Of A Series Of Oligonucleotides, Enrique Dilone Oct 1998

Influence Of 5'-(Tg)1-3- And 3'-(Ac)1-3-Overhangs On The Thermodynamic And Na+ Binding Properties Of A Series Of Oligonucleotides, Enrique Dilone

Seton Hall University Dissertations and Theses (ETDs)

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Auger Resonance Decay Process In Ar 2p Shell Excitation And Ionization, Y. Lu, Wayne C. Stolte, J.A. R. Samson Oct 1998

Auger Resonance Decay Process In Ar 2p Shell Excitation And Ionization, Y. Lu, Wayne C. Stolte, J.A. R. Samson

Chemistry and Biochemistry Faculty Research

The production and subsequent autoionization of the Ar+ (1D2)6d1 satellite state that is formed either by shake-up or recapture during the Auger decay of a 2p vacancy in Ar has been studied by photoelectron spectroscopy in the energy region from 243 to 256 eV. The creation of near zero energy electrons below and immediately above the Ar 2p ionization threshold is discussed. Some ambiguous points in previous studies are clarified.

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Reactions Of Chlorine Atoms With Aromatic Compounds, Barbara O'Leary Oct 1998

Reactions Of Chlorine Atoms With Aromatic Compounds, Barbara O'Leary

Masters

This thesis presents the results of kinetic studies on the reactions of chlorine atoms with a series of aromatic compounds. (please see full text for complete abstract)

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Interagency Lake Mead And Las Vegas Wash Monitoring Program: Standard Operating Procedures Manual, Bureau Of Reclamation, City Of Henderson Water Reclamation Facility, City Of Las Vegas Water Pollution Control Facility, Clark County Sanitation District, Nevada, Southern Nevada Water Authority Oct 1998

Interagency Lake Mead And Las Vegas Wash Monitoring Program: Standard Operating Procedures Manual, Bureau Of Reclamation, City Of Henderson Water Reclamation Facility, City Of Las Vegas Water Pollution Control Facility, Clark County Sanitation District, Nevada, Southern Nevada Water Authority

Publications (WR)

A number of agencies sample Lake Mead and the Las Vegas Wash on a routine basis at several locations. In order to share and properly interpret the data, the Bureau of Reclamation, Southern Nevada Water Authority and the three Wastewater Treatment Facilities (City of Las Vegas, Clark County Sanitation District and City of Henderson) formed a committee to examine sampling and analytical protocols and to share information with the goal of maximizing the data quality. The group first met in April 1997. It was agreed that an effort should be made to discuss and compare specific sampling and analytical techniques …

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Chemical Modification Of Cvd Diamond Electrodes, Robert Matthew Johnson Oct 1998

Chemical Modification Of Cvd Diamond Electrodes, Robert Matthew Johnson

Chemistry & Biochemistry Theses & Dissertations

The micro-array behavior of boron doped CVD diamond thin film electrodes has been studied in acetonitrile containing two redox couples. The analytical technique employed in these studies was cyclic voltammetry. One system is 0.4 mM ferrocene containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAH). This reversible redox system is not only well-known, but also involves only one electron transfer with no breakage/formation of chemical bonds, thus making it a simple system for analysis. The second test is 0.8 mM cobaltocenium hexafluorophosphate, with 0.4 mM ferrocene as an internal standard. Unlike ferrocene, which is neutral initially, cobaltocenium is positively charged, and is reduced …

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Comparison Between Dc-8 And Er-2 Species Measurements In The Tropical Middle Troposphere: No, NoY, O3, Co2, Ch4, And N2O, A. J. Weinheimer, D. D. Montzka, T. L. Campos, J. G. Walega, B. A. Ridley, Stephen G. Donnelly Ph.D., E. R. Keim, L. A. Del Negro, M. H. Proffitt, J. J. Margitan, K. A. Boering, A. E. Andrews, B. C. Daube, S. C. Wofsy, B. E. Anderson, J. E. Collins, G. W. Sachse, S. A. Vay, J. W. Elkins, P. R. Wamsley, E. L. Atlas, F. Flocke, S. Schauffler, C. R. Webster, R. D. May, M. Loewenstein, J. R. Podolske, T. P. Bui, K. R. Chan, S. W. Bowen, M. R. Schoeberl, L. R. Lait Sep 1998

Comparison Between Dc-8 And Er-2 Species Measurements In The Tropical Middle Troposphere: No, NoY, O3, Co2, Ch4, And N2O, A. J. Weinheimer, D. D. Montzka, T. L. Campos, J. G. Walega, B. A. Ridley, Stephen G. Donnelly Ph.D., E. R. Keim, L. A. Del Negro, M. H. Proffitt, J. J. Margitan, K. A. Boering, A. E. Andrews, B. C. Daube, S. C. Wofsy, B. E. Anderson, J. E. Collins, G. W. Sachse, S. A. Vay, J. W. Elkins, P. R. Wamsley, E. L. Atlas, F. Flocke, S. Schauffler, C. R. Webster, R. D. May, M. Loewenstein, J. R. Podolske, T. P. Bui, K. R. Chan, S. W. Bowen, M. R. Schoeberl, L. R. Lait

Chemistry Faculty Publications

We compare measurements of six species taken aboard NASA DC-8 and ER-2 aircraft during two flight legs in the tropical middle troposphere near Hawaii. NO, NOy, O3, CH4, and N2O measurements agree to within the limits set by the known systematic errors. For CO2, which can be measured with better relative precision than the other five species, differences in measured values from the two platforms are slightly larger than expected if the air masses sampled by the two aircraft were indeed similar in CO2 composition to better than 0.08%. Copyright 1998 by the American Geophysical Union.

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Simultaneous Formation Of Functional Leading And Lagging Strand Holoenzyme Complexes On A Small, Defined Dna Substrate, Anthony J. Berdis, Stephen J. Benkovic Sep 1998

Simultaneous Formation Of Functional Leading And Lagging Strand Holoenzyme Complexes On A Small, Defined Dna Substrate, Anthony J. Berdis, Stephen J. Benkovic

Chemistry Faculty Publications

The biochemical characterization of leading and lagging strand DNA synthesis by bacteriophage T4 replication proteins has been addressed utilizing a small, defined primer/template. The ATP hydrolysis activity of 44/62, the clamp loading complex responsible for holoenzyme assembly, was monitored during assembly of both the leading and lagging strand holoenzyme complex. The ATPase activity of 44/62 diminishes once a functional holoenzyme is assembled on both the leading and lagging strand. The assembly of the lagging strand holoenzyme is facilitated by several factors including biotinylated streptavidin blocks at the end of the fork strands, preassembly of the leading strand holoenzyme, and by …

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Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw Sep 1998

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw

Faculty Publications

No abstract provided.

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Electron Transfer Catalysis Of The Hydrogenolysis Of Acyl Dicarbonyl Cyclopentadienyliron Complexes By Tributyltin Hydride, Christian Amatore, Mekki Bayachou, Olivier Buriez, Jean Noel Verpeaux Sep 1998

Electron Transfer Catalysis Of The Hydrogenolysis Of Acyl Dicarbonyl Cyclopentadienyliron Complexes By Tributyltin Hydride, Christian Amatore, Mekki Bayachou, Olivier Buriez, Jean Noel Verpeaux

Chemistry Faculty Publications

The conversion of acyl dicarbonyl cyclopentadienyliron compounds Cp(CO)2Fe(COR) into aldehydes is not straightforward. It is shown here, mainly from electrochemical results, that the hydrogenolysis of the metal acyl bond can be efficiently achieved by trialkytin hydrides under very mild conditions, according to a chain reaction process initiated by an electron transfer to the acyl complex. The expected aldehyde is formed together with the heterobinuclear iron-tin complex.

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Validity Of Tolman’S Equation: How Large Should A Droplet Be?, Kenichiro Koga, Xiao Cheng Zeng, A.K. Shchekin Sep 1998

Validity Of Tolman’S Equation: How Large Should A Droplet Be?, Kenichiro Koga, Xiao Cheng Zeng, A.K. Shchekin

Xiao Cheng Zeng Publications

Surface tension and the length δ (distance between the Gibbs surface of tension Rs and the equimolar surface Re) of simple liquid droplet (Lennard-Jones and Yukawa) are computed over a wide range of droplet sizes up to about 4x106 molecules. The study is based on the Gibbs theory of capillarity combined with the density–functional approach to gas–liquid nucleation. Since this method provides behavior of the surface tension fully consistent with the tension of the planner surface, the constant in Tolman’s equation δx can be determined unequivocally from the asymptotic behavior of σ s . Comparison …

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Sequence-Specific Photomodification Of Dna By An Oligonucleotide-Phenanthrodihydrodioxin Conjugate, Kestutis G. Bendinskas, Andreas Harsch, R. Marshall Wilson, W. Robert Midden Sep 1998

Sequence-Specific Photomodification Of Dna By An Oligonucleotide-Phenanthrodihydrodioxin Conjugate, Kestutis G. Bendinskas, Andreas Harsch, R. Marshall Wilson, W. Robert Midden

Chemistry Faculty Publications

We introduce a new member of a family of photochemically active oligonucleotide conjugates. A Phenanthrodihydrodioxin (PDHD)-based agent was synthesized and covalently linked to a 5'-end of the 9-mer oligonucleotide via a hexamethylene linker. The conjugate hybridized to a complementary 30-nucleotide-long target and efficiently cleaved it in a sequence specific manner. Up to 67% of target was specifically damaged (51% cross-links and 16% direct cleavage). While the photosensitizer alone nonspecifically damaged only Gs in a single-stranded target, its conjugate cross-linked to and damaged also A, T, and C sites in a target in agreement with duplex and tripler formation.

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Bubble Fractionation Of Enantiomers From Solution Using Molecularly Imprinted Polymers As Collectors, Daniel W. Armstrong, J. M. Schneiderheinze, Y. S. Hwang, B. Sellergren Sep 1998

Bubble Fractionation Of Enantiomers From Solution Using Molecularly Imprinted Polymers As Collectors, Daniel W. Armstrong, J. M. Schneiderheinze, Y. S. Hwang, B. Sellergren

Chemistry Faculty Research & Creative Works

Adsorptive bubble separation methods have been used to enrich components from both heterogeneous and homogeneous solutions. These methods are particularly effective for processing large solution volumes at low cost Previous work demonstrated that chiral, surface-active collectors could be used to enrich enantiomers from homogeneous solution in a foam fractionation process. In a significant extension of this work, the use of highly selective molecularly imprinted polymers (MIPs) and heterogeneous solutions for the bubble flotation of enantiomers was evaluated. The high selectivity and ease of recycling of the MIP make this a potentially powerful approach for process-scale separations from large-volume bulk solutions. …

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Nucleotide Or Nucleoside Photoaffinity Compound Modified Antibodies, Methods For Their Manufacture And Use Thereof As Diagnostics And Therapeutics, Boyd E. Haley, Heinz Köhler, Krishnan Rajagopalan, Gabriela Pavlinkova Sep 1998

Nucleotide Or Nucleoside Photoaffinity Compound Modified Antibodies, Methods For Their Manufacture And Use Thereof As Diagnostics And Therapeutics, Boyd E. Haley, Heinz Köhler, Krishnan Rajagopalan, Gabriela Pavlinkova

Chemistry Faculty Patents

Sites on antibodies having affinity for photoaffinity compounds, in particular purine or azidopurine containing compounds are taught. Such photoaffinity sites are contained on a conserved region of different antibody molecules. These sites provide for the site-specific attachment of nucleotide photoaffinity compounds to antibodies, e.g., ATP- or GTP-analog photoaffinity compounds by photochemical means. These nucleotide photoaffinity compounds may additionally be attached to molecules having a desired therapeutic or diagnostic activity, and the resultant conjugates used as diagnostics or therapeutics.

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Immunological Relationship Between The Class I Epitope Of Streptococcal M Protein And Myosin, Anthony Quinn, Kent Ward, Vincent A. Fischetti, Mark E. Hemric, Medeleine W. Cunningham Sep 1998

Immunological Relationship Between The Class I Epitope Of Streptococcal M Protein And Myosin, Anthony Quinn, Kent Ward, Vincent A. Fischetti, Mark E. Hemric, Medeleine W. Cunningham

Faculty Publications and Presentations

The class I epitope of streptococcal M protein is an epidemiological marker for acute rheumatic fever (ARF)-associated serotypes of group A streptococci and is recognized by anti-M protein monoclonal antibody (MAb) 10B6. Using MAb 10B6, we determined the relationship between the class I epitope of M protein and the a-helical coiled-coil protein myosin. MAb 10B6 reacted by enzyme-linked immunosorbent assay and Western blotting with human cardiac myosin and rabbit skeletal myosin and its heavy meromyosin (HMM) subfragment. Overlapping synthetic peptides of M5 protein were used to identify the region of M5 protein recognized by MAb 10B6. Two C repeat peptides …

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Effects Of N-Acetylcysteine And 2,3-Dimercaptosuccinic Acid On Lead Induced Oxidative Stress In Rat Lenses, Rachel Neal, Katherine Cooper, Nuran Ercal, Hande Gürer-Orhan Sep 1998

Effects Of N-Acetylcysteine And 2,3-Dimercaptosuccinic Acid On Lead Induced Oxidative Stress In Rat Lenses, Rachel Neal, Katherine Cooper, Nuran Ercal, Hande Gürer-Orhan

Chemistry Faculty Research & Creative Works

Lead (Pb) is known to disrupt the pro-oxidant/anti-oxidant balance of tissues which leads to biochemical and physiological dysfunction. The present study investigated the previous termeffectsnext term of exposure on the redox status of the lenses of Fisher 344 rats and examined whether antioxidant or chelator administration reversed these changes. Animals were given 5 weeks of 2000 ppm Pb exposure followed by 1 week of either antioxidant, chelator or distilled water administration. Glutathione (GSH) and cysteine (CYS) levels decreased in the Pb-exposed group. N-previous termacetylcysteinenext term or 2,3-dimercaptopsuccinic previous termacidnext term (Succimer) supplementation following Pb intoxication resulted in increases in the …

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Localization Of Sodium, Potassium-Adenosine Triphosphatase In The Cerebral Cortex Of Developing Rats, Maki Ujiie Sep 1998

Localization Of Sodium, Potassium-Adenosine Triphosphatase In The Cerebral Cortex Of Developing Rats, Maki Ujiie

Loma Linda University Electronic Theses, Dissertations & Projects

Active transport via Na+, K+-ATPase plays an important role in establishing and maintaining proper ionic gradient across all mammalian cell membranes. A strict regulation of Na+, and K+ ion levels is especially important in excitable cells such as neurons and myocytes. Inhibition of the enzyme is associated with several pathological conditions and has serious detrimental effects on cerebral cortical cells. Yet the enzyme appears to be limited in amount and distribution in newborn rats. In this study, Na+, K+- ATPase expression and distribution in early postnatal rats were studied …

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Direct Voltammetric Observation Of Redox Driven Changes In Axial Coordination And Intramolecular Rearrangement Of The Phenylalanine-82-Histidine Variant Of Yeast Iso-1-Cytochrome C, Benjamin A. Feinberg, Xiangjun Liu, Michael D. Ryan, Abel Schejter, Chongyao Zhang, Emanuel Margoliash Sep 1998

Direct Voltammetric Observation Of Redox Driven Changes In Axial Coordination And Intramolecular Rearrangement Of The Phenylalanine-82-Histidine Variant Of Yeast Iso-1-Cytochrome C, Benjamin A. Feinberg, Xiangjun Liu, Michael D. Ryan, Abel Schejter, Chongyao Zhang, Emanuel Margoliash

Chemistry Faculty Research and Publications

Direct square-wave and cyclic voltammetric electrochemical examination of the yeast iso-1-cytochrome c Phe82His/Cys102Ser variant revealed the intricacies of redox driven changes in axial coordination, concomitant with intramolecular rearrangement. Electrochemical methods are ideally suited for such a redox study, since they provide a direct and quantitative visualization of specific dynamic events. For the iso-1-cytochrome c Phe82His/Cys102Ser variant, square-wave voltammetry showed that the primary species in the reduced state is the Met80-Fe2+-His18 coordination form, while in the oxidized state the His82-Fe3+-His18 form predominates. The addition or removal of an electron to the …

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Development And Field Testing Of Pulse Introduction Membrane Extraction (Pime) For Measurement Of Ground Water Contamination, Anthony San Juan Aug 1998

Development And Field Testing Of Pulse Introduction Membrane Extraction (Pime) For Measurement Of Ground Water Contamination, Anthony San Juan

Theses

VOCs are a class of aromatic and aliphatic compounds with a variety of functional groups, and are in general detrimental to human health even at trace levels. Conventional analysis of VOCs in groundwater usually involves sampling at site followed by laboratory analysis. This results in long turn around times, high cost and also errors associated with sample preservation during transportation and storage. In order to address these problems, a field portable instrument referred to as Pulse Introduction Membrane Extraction (PIME) has been developed for monitoring trace level halogenated organic contaminants in ground water. A membrane extraction approach has been used, …

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Prospects Of Electrochemistry, Katsumi Niki Aug 1998

Prospects Of Electrochemistry, Katsumi Niki

Journal of Electrochemistry

No abstract provided.

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Direct Electrochemical Reaction Of Cytochrome C At The Poly (Ethylene Oxide) Film Modified Gold Electrodes, Xiao-Gang Qu, Gong-Quan Sun, Hui Yang, Tian-Hong Lu Aug 1998

Direct Electrochemical Reaction Of Cytochrome C At The Poly (Ethylene Oxide) Film Modified Gold Electrodes, Xiao-Gang Qu, Gong-Quan Sun, Hui Yang, Tian-Hong Lu

Journal of Electrochemistry

In this paper, the direct electrochemical reaction of cytochrome c was sudied at the poly (ethylene oxide) film modified gold electrodes. It was found the PEO is a good promoter for the electrochemical reaction of cytochrome c, and the reversibility of reaction of cytochrome c was found to depend on the molecular weight of PEO and the morphology of the PEO films.

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Ac Impedance Study Of The La0.8Sr0.2Mno3/Ysz Electrode, Shi-Zhong Wang, Yi Jiang, Ya-Hong Zhang, Jing-Wang Yan, Wen-Zhao Li Aug 1998

Ac Impedance Study Of The La0.8Sr0.2Mno3/Ysz Electrode, Shi-Zhong Wang, Yi Jiang, Ya-Hong Zhang, Jing-Wang Yan, Wen-Zhao Li

Journal of Electrochemistry

Electrochemical reaction of oxygen on the La0.8Sr0.2MnO3/YSZ electrode has been investigated in detail with AC impedance. The results demonstrated that the rate determining step(rds) of the reaction varies with the temperature, oxygen partial pressure and overpotential applied. At open circuit potential, the rds is the dissociative adsorption of oxygen on the LSM surface. A large number of electron holes are generated at high anodic overpotentials, while oxygen vacancies are formed at high cathodic overpotentials. The formation of the electron holes results in the electronic conduction of the YSZ electrolyte and the extension of the …

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The Hydrogen Evolution Reaction On The Hydrogen Storage Alloy Electrode, Shi-Gang Lu, Qun Li, Qing-Guo Liu, Chun Lu, Bing Dang, Han-Xi Yang Aug 1998

The Hydrogen Evolution Reaction On The Hydrogen Storage Alloy Electrode, Shi-Gang Lu, Qun Li, Qing-Guo Liu, Chun Lu, Bing Dang, Han-Xi Yang

Journal of Electrochemistry

The hydrogen evolution reaction was studied in 1 mol/L KOH solution on the hydrogen storage alloy Mm(NiCoMnAl)5 electrode using open circuit potential decay and ac impedance technique. The reaction was found to proceed by the Volmer(discharge)-Tafel(recombination)mechanism. The measured overpotential η can be subdivided into two components η 1 and η 2 corresponding to the elementary Volmer and Tafel reaction. The Faradaic impedance was analyzed and characterized by the Volmer reaction. Then the exchange current density was evaluated . It was founded that the activity of hydrogen storage alloy electrode for the hydrogen evolution reaction was similar to that of …

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