Chemistry Commons^™

Study Of Electrocrystallized N(N≥40) Multilayers In Boric Acid Solution, Ren-He Yin, Wen-Guang Shi, Wei-Min Cao

Journal of Electrochemistry

Co(0.5 nm～2.2 nm)/Pt(2.0 nm)] n(n>40) multilayers were prepared by electrocrystallization on copper and glass carbon with a dual cell technique under potential control.The periodical modulated structure of the multilayers was demonstrated by the low angle X-ray diffraction. Potential shift negative to the deposition potential of the Co layer and positive to the deposition potential of the Pt layer decreased the value of the full width at half maximum(FWHM) of first Bragg Peak.CoPt ₃ alloy was found as the interface of the multilayers by the middle angle X-ray diffraction.The hysteresis loops show that the easy magnetization of these multilayers lay …

Modification Of Carbon Anode Materials Of Lithium-Ion Secondary Battery, Yuping Wu, Chun-Rong Wan, Chang-Yin Jiang, Jiang-Iun Li

Journal of Electrochemistry

In this paper, the latest research work on modification of carbon anode materials of lithium ion secondary battery is reviewed. Modification methods include: incorporation of nonmetal elements such as boron, silicon, nitrogen, phosphorus and sulfur, metal elements such as potassium, aluminum, gallium and transitional metal elements such as vanadium, nickel, cobalt, copper and iron and surface treatment such as oxidation and formation of surface layer. Since these methods can affect the carbon materials' electronics state, crystal structure and surface structure, the electrochemical properties of the carbon materials could probably be improved. Besides, mechanisms for lithium storage in carbonaceous materials are …

Influence Of Electrolytes To The Interfacial Electroc Characteristics Of The Porous Membrane Of Anodized Aluminum, Ya-Fe Kuang, Ling Wang, Mei-Yuan Wang

Journal of Electrochemistry

The influence of electrolytic composition on the interfacial electric Characteristic of the porous membrane membrance of anodized aluminum was investigated with a electrodialytic method. Results indicated that, when the porous membrane was pretreated with F -, PO 3- 4,SiO 2- 3 and tannic acid, the isoelectric point in 0.01 mol/L KCI, were shifted from normal 9.20 to 3.40, 4.30, 3.30 and 4.50, respectively, and responsive characteristics of ζ potential to pH was changed. Furthermore, after pretreatment of porous membrance with fuchsine basic and fuchsine acid solution,there was no isoelectric point at 2.0

Formation And Effect Of Tribo Cell For Fe Cr Alloy, Dong-Bai Sun, Tao Li, Hong-Ying Yu, De-Ji Yang

Journal of Electrochemistry

The micro galvanic corrosion of 1Cr18 alloy and its effects on the triboelectrochemical behavior were investigated and analyzed in this article. It is shown that the micro galvanic corroson is due to the electrochemical inhomogenity on the surface of the alloy during the friction process. Like galvanic corrosion,the micro galvanic corrosion behaviors are greatly affected by the area ratio of unrubbed to rubbed surface.The load effects on electrochemical behavior of 1Cr18 alloy are also attributed to existence of electrochemical inhomogenity on the surface of materal.

Lithiun Insertion In Carbon Nanotubes, Guo-Tao Wu, Chun-Sheng Wang, Zhong-Fu Qi, Wenz-Hu Li

Journal of Electrochemistry

Carbon nanotubes were produced by chemical vapour deposition(CVD) of acetylene under hydrogen gas.The reversible specific capacity of carbon nanotubes is up to 700 mAh/g, much higher than the theoretical specific capacity of graphite(372 mAh/g).After twenty charge/discharge cycles,the discharge capacity of carbon nanotube anode still maintains 65.3% of its original discharge capacity . Besides, the charge/discharge efficiency of carbon nanotube in the first charge/discharge cycle was found to improve from 42.6% up to 55.9% by coating carbon nanotubes with copper.

External Transducing Measurement Of The Internal Pressure In Sealed Battery By Resistance Strain Gauge, Han-Xi Yang, Rong-Hui Hu, Xin-Ping Ai, Cong-Zhi Yang, Sheng-Xian Li

Journal of Electrochemistry

A novel method to monitor dynamically the internal pressure of sealed battery with no damage of the battery by using of resistance strain measurement technique is presented. This technique employs the resistence strain gauges in touch of the battery case and to detect the minimal change in the battery deformation due to the increasing internal pressure, electrode expantion or intrenal temperature rise. Application of the technique for the study of the effects of the battery processing factors on the battery performance is described taking Ni MH battery as example.

Photoelectrochemical Studies On Nanoporous Tio2/Pan Film Electrode, Min-Sheng Liu, Yan-Zhong Hao, Xue-Bin Qiao, Mai-Zhi Yang, Sheng-Min Cai

Journal of Electrochemistry

The photon to electricity conversion process of nanoporous TiO₂/PAn film electrode was studied in electrolytes with and without redox couple by using the photocurrent action spectra and potential dependence of photocurrent. It is concluded that the nanoporous TiO₂/PAn film electrode has a structure of duplex n type semiconductor layers. The band gap of PAn film is 2.88eV.The TiO₂ nanoporous film electrode modified by PAn can extend the range of optical absorption into visible and infrared region and effectively increase the photocurrent in the visible and infrared region. The photocurrent threshold shifts to>600nm and conversion …

Studies On The Electrode Kinetics Of Electrooxidation Of Mn2+, Wan-Li Hu, Tong Su, Wei Guo, Ding Zhou

Journal of Electrochemistry

The mechanism of electrooxidation of MnSO₄ on Pb Sb As alloy anode was investigated by using rotating disc electrode technique. The results shown that the conditional standard potential of Mn(Ⅲ)/Mn(Ⅱ)in 40% H₂SO₄ is 0.886 4 V.The rate controlling step of electrode process is mixed controlled by charge transfer and diffusion.

Electrochemical Behavior Of Chemically Prepared Ring-Substituted Polyanilines, Li-Zong Dai, Hui-Huang Wu

Journal of Electrochemistry

Polyaniline (PAn) has been known as a promising conducting polymer for technological applications. In research work elecrochemically synthesized PAn has been frequently used since electropolymerization is convenient to prepare the polymer film with controllable thickness or dopingon electrodes. However , the processibility of elecrosynthesized PAn is too poor to produce largearea devices because of its insolubility and infusibility. Recently, therefore, chemical polymerization has attracted a considerable attentionfl-3],  especially suitably derivatized ring substituted (e.g. alkyl or alkoxy) polyanilines have been synthesized, and their appreciable solubility in commonorganic solvents enable the preparation of film on industrial scale by casting. Moreover, emulsionpolymerization reduces …

Electrochemical Determination Of Trace Amouns Of Gold(Ⅲ)By Cathodic Sptripping Voltammetry Using A Carborn Paste Electroele Modified With Bacteria, Rong-Zong Hu, Hao Xu, Jin-Kun Fu, Wen-Yun Hu, Yan-Zhen Chen

Journal of Electrochemistry

An electrochemically pretreated carbon paste electrode modified with bacteria has been studied and used for determination of trace amounts of gold(Ⅲ). A detection limit of 1 ng/mL was obtained by applying cathodic stripping valtammetry. There is a linear relationship between the concentration and peak height in the range of 10～100 μg/mL. The ralative standard deviation of the response to 84.7 μg/mL Au(Ⅲ) is 3.43%.

Li-Ion Intercalation Charactersitic Of Gas-Coke, Zheng-Hua Deng, Xiao-Zheng Zhang, Xiao-Bing Ding, Mian-Zhong Chen, Wei-Guo Xie, Guo-Xiang Wan

Journal of Electrochemistry

A novel of carbon gas coke prepared from natural gas by thermoplasma technology has been studied. The cyclic voltametry and charge discharge test for the Li/gas coke cell demonstrated that this gas coke material has a good performance of the Li ion intercalation characteristic. X-ray diffraction pattern of the gas cokeis showed that the structure of gas coke is similar to the graphite and collapsed from order to disorder during the charge discharge cycles. The gas coke electrode give rise to a new diffraction peak at a low angle after intercalating Li ion and a reversible capacity with 235 mAh/g …

Study Of Proton Exchange Membrane Fuel Cells(Pemfc), Shan-Hai Ge, Bao-Lian Yi, Hong-Fen Xu, Ming Han, Zhi-Gang Shao

Journal of Electrochemistry

The electrode kinetic parameters for proton exchange membrane fuel cells(PEMFC) were investigated by measuring the relations of cell potential and current density. An experimental stack of PEMFC which can be operated at E cell =0.7V, I =0.55A/cm² steadily is presented, and the effects of electrode structure and operation conditions such as temperature, pressure, humidification, flow rate on the performance of PEMFC are discussed.

Studies On The Preparation Of Nanophase Electrode Materials And Its Electrochemical Properties(Ⅲ)—Performance Of Nm-Γ-Mno2 Obtained By Microemulsion Method, Ling Liu, Xi Xia

Journal of Electrochemistry

A nanophase MnO₂ was synthesized using w/o microemulsion as reation media, The most favorable experiment conditions for the preparation of nm MnO₂ were researched. XRD,TEM,AC impedance, cyclic voltammetry etc. examinations were used to characterize the sample comparison with the classical MnO₂ (I.C.No.1EMD,electrolytic manganese dioxide). Sample shows that the crystal styucture of the synthesized samples are mainly γ-MnO₂, with average particle size in the nanometer as shown by TEM. It was found that the discharge capacity of nm MnO₂ obtained is significantly higher than that of the I.C.No.1 EMD.

Electrooxidation Of Benzene To Benzoquinone In A Packed Bed Reactor, Xin-Sheng Zhang, Ping Ding, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

A packed electrode reactor was used to oxidize to benzoquinone. Anode bed of the reactor has a size of 10～30 mm×450 mm×50 mm(thickness×length×width),and was packed porous lead alloy. A dispersion of benzene in 1 mol/L aqueous sulfuric acid was passed through the reactor. Current efficiency for benzoquinone generation is 62.9% at optimal operating condition: velocity of electrolyte flow, 0.19 ms ^-1 ;current, 10 A; thickness of anode bed, 10 mm, and percentage of benzene, 24%.

Correlation Function Formulation For The State Selected Total Reaction Probability, Sophya Garashchuk, David J. Tannor

Faculty Publications

Investigates the correlation function formulation for the state selected total reaction probability. Discussion of the wave packet propagation; Derivation of the correlation function expression for the N[sub alpha](E); Application of quantum-mechanical and Herman-Kluk propagation methods.

Detergent-Salt Resistance Of Lap2Α In Interphase Nuclei And Phosphorylation-Dependent Association With Chromosomes Early In Nuclear Assembly Implies Functions In Nuclear Structure Dynamics, Thomas Dechat, Josef Gotzmann, Andreas Stockinger, Crafford A. Harris, Mary Ann Talle, John Siekierka, Roland Foisner

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Lamina-associated polypeptide (LAP) 2 of the inner nuclear membrane (now LAP2β) and LAP2α are related proteins produced by alternative splicing, and contain a common 187 amino acid N-terminal domain. We show here that, unlike LAP2β, LAP2α behaved like a nuclear non-membrane protein in subcellular fractionation studies and was localized throughout the nuclear interior in interphase cells. It co-fractionated with LAP2β in nuclear lamina/matrix-enriched fractions upon extraction of nuclei with detergent, salt and nucleases. During metaphase LAP2α dissociated from chromosomes and became concentrated around the spindle poles. Furthermore, LAP2α was mitotically phosphorylated, and phosphorylation correlated with increased LAP2α solubility upon extraction …

Orientation Of Nickelocene On Ag(100), D. L. Pugmire, C. M. Woodbridge, Marjorie Langell

Marjorie A. Langell Publications

High-resolution electron-energy-loss spectroscopy has been used to study the molecular adsorption of nickelocene, Ni(C₅H₅)₂, on Ag(100). Results indicate that at up to one monolayer coverage, nickelocene adsorbs molecularly with its axis approximately perpendicular to the surface. At very high coverages, the molecular axis is not exclusively oriented along the surface normal. This is possibly due to randomization of the metallocene orientation as multilayers are formed.

Highly Enantioselective Hplc Separations Using The Covalently Bonded Macrocyclic Antibiotic, Ristocetin A, Chiral Stationary Phase, K. Helen Ekborg-Ott, Youbang Liu, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The macrocyclic glycopeptide, ristocetin A, was covalently bonded to a silica gel support and evaluated as a liquid chromatographic (LC) chiral stationary phase (CSP). Over 230 racemates were resolved in either the reversed-phase mode, the normal-phase mode, or the polar-organic mode. The retention behavior and selectivity of this CSP were examined in each mode. Optimization of separations on this column is discussed. The ristocetin A CSP appeared to be complimentary to other glycopeptide CSPs (i.e., vancomycin and teicoplanin). Column stability was excellent. The CSP was not irreversibly altered when going from one mobile phase mode to another.

Capillary Electrophoretic Separation Of Sulfoxides, Clair Davies

Masters Theses & Specialist Projects

Chiral sulfoxides are most widely used in asymmetric synthesis. Their application as chiral synthons has now become a well-established and reliable strategy, mainly due to availability and high asymmetric induction exerted by the chiral sulfinyl group. Very few articles have been published on the separation of chiral sulfoxides; most involve HPLC or GC. The first separation of optically active sulfoxides was described by Phillips and co-workers. To date no work has been reported using capillary electrophoresis for the separation of alkylaryl sulfoxides. A series of alkylaryl sulfoxides were synthesized. Conditions for their separation were investigated using a modified 125 mM …

A Study Of High Temperature Corrosion In An Afbc System, Wie Xie

Masters Theses & Specialist Projects

The occurrence of furnace wall and superheater corrosion in fluidized bed combustor systems has caused some operational and economic concerns. It is generally accepted that chlorine and sulfur may play roles in this corrosion. In order to predict the performance of high chlorine or high sulfur coals in these combustion systems, it is necessary to have a better understanding of the different corrosion mechanisms in which chlorine and sulfur may be involved. It is also important to evaluate the critical point of coal chlorine content which may cause initial corrosion. The laboratory-sized atmospheric bed combustor (AFBC) at Western Kentucky University …

Neutron Diffraction And Mössbauer Spectral Study Of Nd₂Fe₁₆Ti And Its Nitride, Fernande Grandjean, Peter C. Ezekwenna, Gary J. Long, Oran Allan Pringle, P. H. L'Héritier, Mohamed Ellouze, H. P. Luo, William B. Yelon

Chemistry Faculty Research & Creative Works

The 295 K powder neutron diffraction patterns and the temperature dependence of the Mössbauer spectra of Nd₂Fe_17-xTi_x and Nd₂Fe_17-xTi_xN_x have been measured. A Rietveld refinement of the neutron diffraction patterns yields the Nd₂Fe_16.32Ti_0.68 and Nd₂Fe_16.32Ti_0.68N_2.7 stoichiometries for the two compounds and indicates that titanium occupies only the 6c crystallographic site and nitrogen only the 9e site in the rhombohedral Th₂Zn₁₇ structure. The insertion of interstitial nitrogen into Nd₂Fe_16.32Ti_{0.68 …}

The Effects Of So2 On The Formation Of Cl2 During Co-Firing Muncipal Solid Waste With Coal, Ying Xie

Masters Theses & Specialist Projects

The Deacon Reaction was proposed as a mechanism for the formation of molecular chlorine during the combustion of municipal solid waste (MSW): 4HCl + O2 ↔ 2Cl2 + 2H2O As suggested by some researchers, co-firing high sulfur coal with MSW may reduce the emission of toxic chlorinated organics, resulting from the reaction between S02 and Cl2: SO2 + Cl2 + H2O → SO3 + 2HCl The effect of sulfur dioxide on the formation of chlorine through the Deacon Reaction is investigated in this study. A Lindberg Furnace was utilized and preheated to 800°C to simulate the conditions in the AFBC …

Improvement Of Epa Method 8330: Complete Separation Of Explosives Using A Two Phase Approach, Michael J. Lang

Masters Theses

A wide range of primary and secondary contaminants is found in environmental matrices containing explosive residues. HPLC methodology for the detection of explosive is now standardized in EPA Method 8330, and represents the most common method currently used for explosive analysis. However, co-elution of some of the analytes occurs even using method 8330. As a result, explosive analysis using HPLC have required the use of a confirmation column in an additional analysis step.

In the current work, all of the compounds in the EPA 8330 explosives list were resolved using a single HPLC separation. While the EPA 8330 HPLC conditions …

Orientational Susceptibility And Elastic Constants Near The Nematic-Isotropic Phase Transition For Trimers With Terminal-Lateral-Lateral-Terminal Connections, Daeseung Kang, Milind P. Mahajan, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin

Faculty Publications

Magnetically induced Freedericksz measurements were performed in the nematic liquid crystal phase to extract the elastic constants of a terminal-lateral-lateral-terminal trimer, i.e., a trimer in which the connections to the first and third mesogens are at the end of the mesogen and both attachments to the central mesogen are lateral. Polymeric liquid crystals based on this unit have negative Poisson ratios. Additionally, electric field Kerr measurements were performed in the isotropic phase to extract the orientational susceptibility. The elastic constants were found to be similar to values obtained for typical monomers, albeit with a slightly enhanced ratio K-33/K-11 and reduced …

Enantiomeric Separation Of Unusual Secondary Aromatic Amino Acids, A. Péter, G. Török, G. Tóth, W. Van Den Nest, G. Laus, D. Tourwé, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

High-performance liquid chromatographic and gas chromatographic methods were developed for the separation of unusual secondary aromatic amino acids. Amino acids containing 1,2,3,4-tetrahydroisoquinoline, 1,2,3,4-tetrahydronorharmane-1-carboxylic acid and 1,2,3,4-tetrahydro-3-carboxy-2-carboline moieties were synthetized in racemic or chiral forms. The high-performance liquid chromatography was carried out either on a teicoplanin-containing chiral stationary phase or on an achiral C18 column. In the latter case the diastereomers of the amino acids formed by precolumn derivatization with the chiral reagents 2,3,3,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate or 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide were separated. The gas chromatographic analyses were based on separation on a Chirasil-L-Val column.

40th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 40th 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, July 25 - August 1, 1998.

Role Of The Maillard Reaction In Aging Of Tissue Proteins: Advanced Glycation End Product-Dependent Increase In Imidazolium Cross-Links In Human Lens Proteins, Elisabeth Brinkmann Frye, Thorsten P. Degenhardt, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Dicarbonyl compounds such as glyoxal and methylglyoxal are reactive dicarbonyl intermediates in the nonenzymatic browning and cross-linking of proteins during the Maillard reaction. We describe here the quantification of glyoxal and methylglyoxal-derived imidazolium cross-links in tissue proteins. The imidazolium salt cross-links, glyoxal-lysine dimer (GOLD) and methylglyoxal-lysine dimer (MOLD), were measured by liquid chromatography/mass spectrometry and were present in lens protein at concentrations of 0. 02-0.2 and 0.1-0.8 mmol/mol of lysine, respectively. The lens concentrations of GOLD and MOLD correlated significantly with one another and also increased with lens age. GOLD and MOLD were present at significantly higher concentrations than the …

Synthesis And Characterization Of Large Stereoregular Organosiloxane Cycles, O. I. Schchegolikhina, V. A. Igonin, Yulia A. Molodtsova, Yu. A. Pozdniakova, Alexandr A. Zhdanov, T. V. Strelkova, Sergey V. Lindeman

Chemistry Faculty Research and Publications

The large stereoregular phenyltrimethylsiloxysiloxane macrocycles of general formula [PhSi(OSiMe₃)O]_n (n=6 and 12) have been selectively obtained with high yields by trimethylsilylation of cage-like oligophenylmetallasiloxanes (OPMS) which we described earlier. The compounds 3 (n=6) and 4 (n=12) have been characterized by NMR-spectroscopy method and by single crystal X-ray analysis. This investigation showed unambiguously that the siloxane macrocycles keep their size and configuration (the same as in the initial OPMS) during the trimethylsilylation. Thus a synthetic route for obtaining large stereoregular siloxane macrocycles has been developed.

Selective Determination Of Methylmercury By Flow-Injection Fast-Scan Voltammetry, Rebecca Lai, Eva Huang, Feimeng Zhou, David O. Wipf

Rebecca Lai Publications

A simple flow-injection system, suitable for solution flow rates at microliters-per-minute, has been combined with fast-scan voltammetry for selective determination of methylmercury. A thin Hg film was formed at a Pt microelectrode prior to the measurement. Detection of methylmercury is carried out by measuring the oxidation of methylmercury radicals that have been generated at the Hg microelectrode. At slow scan rates, the electrogenerated methylmercury radicals undergo a follow-up dimerization reaction to form dimethyldimercury (E_rC_i² mechanism). At fast scan rates, it was found that methylmercury radicals can be quantitatively reoxidized (reversible electron-transfer). Optimization of the experimental conditions …

2-Phenyl-3-(5,6,7,7a-Tetrahydro-1h,3h-Pyrrolo[1,2-C]Oxazol-3-Ylidene)-1-Propene-1,1-Dicarbonitrile And 4-(4-Methoxyphenyl)-2,6-Bis(Methylthio)Pyridine-3-Carbonitrile, M. George, S. Das, C.V. Ashokan, N.P. Rath, M.V. George

Chemistry & Biochemistry Faculty Works

The reaction of 3-aryl-2-cyano-5,5-bis(methylthio)penta-2,4-dienenitrile, (1), with (L)-(-)-2-hydroxymethylpyrrolidine, (2), gave two types of product, the normal substitution product, (3), and a pyridine derivative, (4). The structures of two representative examples, 2-phenyl-3-(5,6,7,7a-tetrahydro1H,3H-pyrrolo[1,2-c]oxazol-3-ylidene)-1-propene-1,1-dicarbonitrile, (3a), as its hemibenzene solvate, C17H14N3O.0.5C6H6, and 4-(4-methoxyphenyl)-2,6-bis(methylthio)pyridine-3-carbonitrile, (4b), C15H14N2OS2, have been unambiguously established by X-ray crystallographic analysis. The molecular packing of (4b) involves loosly held dimers with S1...S1' distances of 3.424 (1) Å.