Physical Sciences and Mathematics Commons^™

Effects Of The Surfactant And Ph On Linear Potential Scan Of Aqueous Na 2s Solution, Qingfeng Yi

Journal of Electrochemistry

In presence of a cationic surfactant HTAB,linear potential scans for Na 2S at graphite anode in both saturated sodium tetra_borate solution and 1 mol·L -1 NaOH solution, have been investigated.Results show that anodic current density increases and peak potentials shift to more negative with the increase of HTAB concentrations. The anodic current densities increased by addition of HTAB are larger in 1 mol·L -1 NaOH than those in saturated sodium tetra_borate solution,resulting from different acting forces of HTAB with various charged electro-active species .Both oxidation and reduction peaks in cyclic voltammograms for Na 2S containing solution become sharper if HTAB …

The Effects Of Metallic Cobalt Abbition On The Performance Of Pasted Nickel Electrodes, Anbao Yuan, Jianqing Ding Wanchun Zhang, Shaoan Cheng, Chunan Cao

Journal of Electrochemistry

The Ni_foam pasted nickel electrodes prepared by coprecipitated Ni 1_X Zn X(OH) 2 with and without cobalt power addition have been studied. The electrode with addition of metallic cobalt showed a higher performance both in discharge capacity and cycle life.It is known from the experiment results that the addition of Co can remarkably increase the active material utilization which is suggested to be improvement of discharge depth due to the conducting CoOOH formed in the first activation charging.The superior capacity during cycling could be attributed to the synergistic action of zinc and cobalt addition,especially to the coprecipitatation of zinc hydroxide …

Influence Of Thiourea And Its Derivate On The Process Of Cathodic Electrodeposition Of Copper, Dong Dong, Yunhui Yunhui, Aihong Zou, Yunxia Zhao

Journal of Electrochemistry

The effects of thiourea and its derivate on the electrodeposition of copper from the dilute acid sulphate solutions have been studied by using potential sweep techniques at quasisteady state. Limiting current densities( I d),exchange current densities( i 0) and αn are obtained by data processing with the least square method.Thiourea has a depolarizing effect on the copper depositing at concentrations below 8 mg·L -1 ,and a polarizing effect at higher concentration (>10 mg·L -1 ),and it changes the mechanism of copper deposition reaction.Propenyltiourea and Phenylthiourea have a depolarizing effect on the copper depositing,but the mechanism of copper deposition reaction …

The Techniques Of The Paired Electrosynthesis, Hongkun Zhang, Dengping Gu

Journal of Electrochemistry

In this Paper,we introduce our work on paired electrosynthesis.In conjunction with our research practice,we introduce electrolytic conditions,such as material of electrode ,courrent density and electrolytic temperature etc,as reference for researcher.We categorize the paired electrosynthesis techniques to widen our view on the paired electroorganic synthesis and to promote the deveopments of paired electrosynthesis techniques.

Preparation And Ionic Conductivity Of Nanometer_Sized Li 2+X Gd X Si 1+X O 3 By The Sol_Gel Method, Rufen Chen, Xiuqin Song, Huating Liu

Journal of Electrochemistry

Li 2+x Gd xSi 1-x O 3( x =0～0.15) samples have been prepared by the Sol_Gel method. The power samples were characterized by DTA_TG, XRD and TEM. Ionic conductivity of the sinter was determined by means of A_C impedance measurements. The experimental results showed that the range of solid_solution was 0< x ≤0.09, while the conductivity of samples raised with increasing amount of Gd 2O 3 added, and average grain size of samples was 80 nm. In comparing with the samples by the conventional solid state reaction, the samples prepared by Sol_Gel method required lower temperature and presented higher ionic conductivity.

A New Method For Preparing Self_Assembled Lipid Bilayers On Pt Electrode, Peng Diao, Dianlu Jiang, Xiaoli Cui, Dengping Gu, Ruting Tong

Journal of Electrochemistry

A new method for preparing Pt_supported bilayer lipid membrane(Pt_BLM) on Pt electrode cleaned by high power ultrasound was reported.The reported method was convenient,costing less platinum and could be used to form large_area Pt_BLM as compared with the traditional Pt_wire_cutting method.The electrical properties of Pt_BLM were studied using electrochemical impedance spectroscopy and cyclic voltammetry.Experimental results showed that the values of membrane capacitance and the voltammetric characteristics were consistent with those of Pt_BLM prepared by traditional method.

Structural And Electrochemical Studies On Lithium Manganese Oxide Containing Li + Prepared By Hydrothermal Method For Lithium Ion Batteries, Deyao Liu, Jinkua You, Wei Chu, Yong Yang, Zugeng Lin

Journal of Electrochemistry

In this paper, Todorokite manganese oxides containing Li + with large tunnel structure(sample M5) have been synthesized by hydrothermal methods from natural manganese oxide nano fiber (sample M4). The structure and composition of the samples were characterized and analyzed by XRD, ICP, TGA and DTA. Its electrochemical behavior as a cathode materials for rechargeable lithium ion insertion were studied by galvanostatic charge/discharge measurements. XRD results show that the sample M4 is mainly composed of Birnessite and Vernadite structure. Although the sample M4 shows a high initial capacity of approximately 150 mAh/g, its performances decrease gradually over 30 cycles. It is …

Electrochemical Synthesis Of Fes Electrode And Its Behavior Measurement, Congsheng Guan

Journal of Electrochemistry

The Potential for the electrochemical synthesis of FeS electrode has been obtained by cyclic voltammetry.FeS electrodes were synthesiaed by controlling Fe electrode at -1.0 V in LiCl_KCl_Li 2S and Li(FClI)_Li 2S melts and their behavior were measured also.The FeS electrode synthesized in molten Li(FClI)_Li 2S has the best charge and discharge properties.

Studies On The Inclusion Complexes Of Rhein With Cds By Oscilloscope Polarography, Xiangjun Li, Jun Lian, Yoing Zhang, Jinghao Pan

Journal of Electrochemistry

Inclusion action of rhein with CDs was studied by linear sweep oscilloscope polarography. The molar ratio of inclusion complexes of rhein with CDs are 11, the inclusion constants in different temperature have been determined and the thermodynamics parameter of some inclusion complexes have also been obtained. It indicates that in normal temperature, the inclusion procedure go on spontaneously, improving temperature is unfavorable to the formation of inclusion complexes.

The Electrochemical Apparent Effective Thickness Of Alkanethiol Self_Assembled Monolayers, Xiaoli Cui, Dianlu Jiang, Peng Diao, Junxin Li, Ruting Tong, Dengping Gu, Xinkui Wang

Journal of Electrochemistry

The electrochemical behavior of octadecanethiol self_assembled monolayers modified gold electrode in different concentration of Fe(CN) 3-/4- 6 is investigated by cyclic voltammetry and electrochemical impedance spectroscopy .It is determined that the apparent he_terogeneous rate constant k s is in the order of 10 -6 cm·s -1 ,the apparent electron transfer coefficients are 0.15 and 0.22.The apparent effective thickness of the SAMs is established which can be used to describe the molecular ordering degree of self_assembled monolayers.

Calculation Of Corrosion Rate Of Passive Metals With Charge Curve Analysis Technique, Yuansheng Zhang, Min Gong

Journal of Electrochemistry

This work contains two parts:(1)A charge curve equation having no appro_ximation for passivated metal corrosion systems is derived and compared with the routine charge curve equation,which is virtual only when the polarization is minim(linear range)(2)It is simpler to analyze charge curve data by from of charge differential equation than from charge curve equation.After the charge curve data are measured,the slope of charge curve is computed by numerical differentiation method,then the charge differential equation may be transformed to a set of linear equations using polynomial approximation.The electrochemical parameters of corrosion system would be calculated out from this set of linear equations …

In Situ Ftirs Studies Of The Electrochemically Induced Coupling Of Osmium Nitrido Species In Acetonitrile, Shengpei Chen, Shigang Sun

Journal of Electrochemistry

he search for inorganic systems that can cleave N≡N triple bond under mild conditions is an important subject. It is well known that the metal nitrido (M≡N) complexes are possible intermediates in nitrogen fixation [1] and in the reduction of nitrite to ammonia [2,3] . Recently, these complexes have received considerable attention [4～9] for their intriguing photochemical and electrochemical properties. Among different high valence metal nitrido complexes, some osmium(VI) nitrido species are stable enough to be isolated [4～10] , demonstrating that the study on this class of complexes becomes feasible. Meyer and co_workers [4] have reported the electrochemical interconversion between …

The Ac Impedance Analysis For Pluse Oxide Film Of Aluminium Alloy, Ailing Du, Xicheng Ma, Heming Zhang

Journal of Electrochemistry

Bode diagrams for aluminum PC (abbreviated from pulse current) oxide films were first obtained by AC impedance measurements in a wide range of frequency.The experimental results show that different kinds of electrical equivalent circuits can be used for representing PC films and DC (abbreviated from direct current) oxide films separately,the main differences between them are their porous layers,the PC films are more even with little defects.Those are also verified by SEM and V I characteristic curve measurements.

A Patching Model For Surface Tension And The Tolman Length, T.V. Bykov, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

In the framework of density functional theory (DFT), a patching model for the density profile of the liquid–vapor interface is developed. The patching is based on analytical expressions of the asymptote of the density profiles. Derived from the model the surface tension of planar liquid–vapor interface as well as the Tolman length can be computed from analytic expressions. Two prototype systems are considered; the Yukawa and the Lennard-Jones. As a result, the temperature dependence of the surface tension as well as the Tolman length are obtained. The results are compared with numerical DFT calculations.

Assignment Of The Infrared Spectra Of The Methanol Trimer, Gregory S. Tschumper, Jason M. Gonzales, Henry F. Schaefer

Chemistry Faculty Research & Creative Works

Second-order Möller-Plesset perturbation theory (MP2) and density functional theory (DFT) were employed to optimize two cyclic conformations of the methanol trimer, denoted "bowl" and "chair," as well as a third noncyclic, "open-chain" conformation. This is the first time all three methanol trimer conformations have been studied at the same level of theory. Harmonic vibrational frequencies confirm that all stationary points are minima on the intermolecular potential energy hypersurface. The chair is consistently predicted to be the most stable conformer. The bowl and open-chain conformers are only slightly less stable and lie within 3 kcal/mol. Results indicate that the bowl structure …

Two-Dimensional Nuclear Magnetic Resonance Correlation Spectroscopy At Zero Field, Ming-Yuan Liao, Gerard S. Harbison

Gerard Harbison Publications

Three methods for two-dimensional correlation nuclear magnetic resonance spectroscopy at zero field are discussed. All three involve coherence transfer via longitudinal polarization, double quantum coherence, or both in parallel. The double quantum pulse sequences exploit the spinor property of spin states. These sequences have been applied to connected Δm=1 transitions, as well as for the indirect detection of forbidden or nearly forbidden Δm.1 transitions.

The Methionyl Aminopeptidase From Escherichia Coli Can Function As An Iron(Ii) Enzyme, Ventris M. D'Souza, Richard C. Holz

Chemistry Faculty Research and Publications

The identity of the physiologically relevant metal ions for the methionyl aminopeptidase (MetAP) from Escherichia coli was investigated and is suggested to be Fe(II). The metal content of whole cells in the absence and presence of expression of the type I MetAP from E. coli was determined by inductively coupled plasma (ICP) emission analysis. The observed change in whole cell concentrations of cobalt, cadmium, copper, nickel, strontium, titanium, and vanadium upon expression of MetAP was negligible. On the other hand, significant increases in the cellular metal ion concentrations of chromium, zinc, manganese, and iron were observed with the increase in …

1H Nmr Studies On The Cua Center Of Nitrous Oxide Reductase From Pseudomonas Stutzeri, Richard C. Holz, Marcela L. Alvarez, Walter G. Zumft, David M. Dooley

Chemistry Faculty Research and Publications

¹H NMR spectra of the Cu_A center of N₂OR from Pseudomonas stutzeri, and a mutant enzyme that contains only Cu_A, were recorded in both H₂O- and D₂O-buffered solution at pH 7.5. Several sharp, well-resolved hyperfine-shifted ¹H NMR signals were observed in the 60 to −10 ppm chemical shift range. Comparison of the native and mutant N₂OR spectra recorded in H₂O-buffered solutions indicated that several additional signals are present in the native protein spectrum. These signals are attributed to a dinuclear copper(II) center. At least …

Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram

Chemistry Faculty Research & Creative Works

A process for enhancing the corrosion resistance of an aluminum-containing component with a cerium based coating. An aluminum-containing cathode and an oxygen- evolving anode are immersed in an electrolyte comprising water, solvent, oxidizing agent and cerium ions. An electrical current is passed through the electrolyte by applying electrical current to deposit a cerium based coating onto the cathode. An electrolyte for use in depositing a cerium based coating. An electrodeposited cerium-based coating. An aluminum aircraft structural component having a cerium-based coating thereon.

Induced Changes In Solvent Structure By Phospholipid Monolayer Formation At A Liquid–Liquid Interface, R. A. Walker, D. E. Gragson, G. L. Richmond

Chemistry and Biochemistry

Vibrational sum frequency spectroscopy has been used in conjunction with dynamic surface tension measurements to study formation of a 1,2-dilauroyl-sn-phosphatidylcholine (DLPC) monolayer at a water–carbon tetrachloride interface. Surface tension measurements show that an aqueous solution of liquid crystalline phosphocholine vesicles (4.5 μM DLPC) requires several hours to form a tightly packed, fully equilibrated monolayer of DLPC monomers. Vibrational spectra of the interfacial region at different stages in the monolayer formation process indicate that the solvent structure undergoes dramatic re-organization as the monolayer forms. Initial adsorption of DLPC monomers severely disrupts the interfacial hydrogen bonding. Intensity in the OH …

Is Hyperconjugation Responsible For The "Gauche Effect" In 1-Fluoropropane And Other 2-Substituted-1-Fluoroethanes?, Paul R. Rablen, R. W. Hoffman, D. A. Hrovat, W. T. Borden

Chemistry & Biochemistry Faculty Works

The energies and geometries of a series of 2-substituted-1-fluoroethanes were computed at the MP2/6-311++G**(6D)//MP2/6-31+G* level of theory for both the maxima and minima of the rotation about the C-C bond. The results did not support the predictions of a hyperconjugative model, that both 1,2-difluoroethane and 1-chloro-2-fluoroethane would strongly prefer a gauche conformation, and that 1-fluoro-2-silylethane would strongly prefer an anti conformation. The existence of competing electrostatic interactions between the fluorine and the substituents at C-2 was indicated by the detailed geometries of the gauche conformers and by the calculated sensitivity of the gauche-anti energy differences to the presence of a …

16. Eli M. Pearce, Otto Vogl, Judith Pearce

Otto Vogl

No abstract provided.

41st Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 41st annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 1-5, 1999.

The Discovery-Oriented Approach To Organic Chemistry. 2. Selectivity In Alcohol Oxidation. An Exercise In 1H Nmr Spectroscopy For Sophomore Organic Laboratories, Ram Mohan, Steven Shadwick

Scholarship

We have developed a simple oxidation experiment that presents the student with a puzzle and is a good exercise in 1H NMR spectroscopy. The experiment, which illustrates the important concept of selectivity in organic synthesis, involves selective oxidation of a mixture of 1-heptanol and 2-heptanol using commercial swimming pool chlorine. 1H NMR analysis of the product mixture allows the student to determine the selectivity exhibited by the reagent.

Hydrogen Dynamics In The Hydrides Of Pr₂Fe₁₇ As Revealed By Mössbauer Spectroscopy, Dimitri Hautot, Gary J. Long, Fernande Grandjean, Olivier Isnard, Salvatore Miraglia

Chemistry Faculty Research & Creative Works

The rhombohedral Pr₂Fe₁₇H_x compounds with the Th₂Zn₁₇ structure have been prepared for x =0-5. Their lattice parameters and Curie temperatures have been determined from powder x-ray diffraction and thermomagnetic measurements, respectively, and their Mössbauer spectra have been measured between 4.2 and 295 K. The Mössbauer spectra for x=0, 1, and 2, obtained between 4.2 and 295 K, and those of Pr₂Fe₁₇H₃, obtained above 90 K, have been analyzed with a seven sextet model, indicative of a basal magnetization in these compounds. The Mössbauer spectra of Pr …

Comparison Of An Advanced Mercury Analyzer With The Cold Vapor Atomic Absorption Technique For The Determination Of Mercury In Coal, Dong Li

Masters Theses & Specialist Projects

For over 30 years the industry standard method for mercury analysis has been the cold vapor atomic absorption spectrometric technique (CVAAS). Recent developments in improving this technique have focused on procedures for concentrating mercury in the analyte or materials to improve detection. The LECO Corporation produces an Advanced Mercury Analyzer, the AMA-254, for analysis of the solid and liquid samples. The system allows for the thermal heating of the sample to decompose the sample and release mercury, which is concentrated in a gold amalgam. Thermal desorption of the mercury from the amalgam is detected by atomic absorption spectroscopy. A comparison …

Analysis Of Galvanized Steel Plates Using Glow Discharge-Atomic Emission Spectrometry, Liang Wang

Masters Theses & Specialist Projects

Combining an intense emission source and a high-speed sputtering source in one, glow discharge atomic emission spectrometer (GD-AES) provides an efficient technique for analyzing surfaces, coatings and bulk solids. The purpose of our work is to explore the optimum lamp operation parameters of SA-2000 for analysis of galvanized steel plate and to investigate the method for qualitatively and quantitatively analyzing the zinc coating. Under the optimum experimental conditions found in our study, which are current of 19-21 mA; voltage of 900-1200 V; pressure 2.0-2.5 torr, the calibration curve is constructed, so that specific zinc concentration can be assign to the …

The Discovery-Oriented Approach To Organic Chemistry. 2. Selectivity In Alcohol Oxidation. An Exercise In 1H Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Steven R. Shadwick

Ram S. Mohan

Protein Adducts Of Iso[4]Levuglandin E2, A Product Of The Isoprostane Pathway, In Oxidized Low Density Lipoprotein, Robert G. Salomon, Wei Sha, Cynthia Brame, Kamaljit Kaur, Ganesamoorthy Subbanagounder, June O'Neil, Henry F. Hoff, L. Jackson Roberts Ii

Pharmacy Faculty Articles and Research

Levuglandin (LG) E₂, a cytotoxic seco prostanoic acid co-generated with prostaglandins by nonenzymatic rearrangements of the cyclooxygenase-derived endoperoxide, prostaglandin H₂, avidly binds to proteins. That LGE₂-protein adducts can also be generated nonenzymatically is demonstrated by their production during free radical-induced oxidation of low density lipoprotein (LDL). Like oxidized LDL, LGE₂-LDL, but not native LDL, undergoes receptor-mediated uptake and impaired processing by macrophage cells. Since radical-induced lipid oxidation produces isomers of prostaglandins, isoprostanes (isoPs), via endoperoxide intermediates, we postulated previously that a similar family of LG isomers, isoLGs, is cogenerated with isoPs. Now …

Nickelocene Adsorption On Single-Crystal Surfaces, D. L. Pugmire, C. M. Woodbridge, S. Root, Marjorie Langell

Marjorie A. Langell Publications

Nickelocene adsorption onto Ag(100), Ni(100), and NiO(100)/Ni(100) surfaces was studied with x-ray photoelectron spectroscopy and high-resolution electron energy loss spectroscopy at 135 K for monolayer and multilayer coverages of NiCp₂. On the relatively inert Ag(100) surface, nickelocene physisorbs molecularly, with its molecular axis perpendicular to the surface plane. Exposure to the reactive Ni(100) surface results in the decomposition of nickelocene into acetylene and acetylene-like fragments and, when this surface is warmed to 273 K, carbide contamination is observed. There is evidence for double-bond carbon on nickelocene-exposed NiO(100), and vinyl and propenyl fragments are the most likely decomposition products …