Physical Sciences and Mathematics Commons^™

Study Of Electrochemistry Of Aloe-Emodin And Determination Of It With 1.5th Order Derivative Anodic Stripping Voltammetry, Xin Hua Lin, Li Ying Huang, Wei Chen, Hong-Bin Luo, Bin Qiu, Chun-Yan Li

Journal of Electrochemistry

In 0.1 mol/L HAc solution(pH=2.89),the voltammetric behaviours of aloe emodin at a glassy carbon electode has been studied. One pair of current peak of the voltammogram may be attributed to a quasireversible two electron transfer of aloe emodin molecules at the glassy carbon electrode. A new method, the derivative anodic stripping voltammetry, for aloe emodin determination is described. The adsorptive potential of aloe emodin is -0.80V(vs. SCE),while its stripping potential is -0.38V(vs.SCE). The peak current is propotional to the concentration of aloe emodin over the range of 2.0×10 -7 ～8.0×10 -6 mol/L. The method is simple, rapid and reliable for …

Analyses On Spm Images And Theoretical Investigations On Oxygen Vacancy Concentration Of Light-Induced Nanostructured Titania Super Hydrophilic Films, Ren-Jie Zeng, Zhong-Hua Lin, Zhi-Min Fang

Journal of Electrochemistry

A typical nanostructured titania super hydrophilic film was chosen for general characterization employing a Scanning Probe Microscope(SPM)and an electrochemical measurement system.Following from the principles of the solid state chemistry and nanomechanics,intensive theoretical. analyses on the SPM images,the oxygen vacancy concentrations and the mechanism of the super hydrophilicity were made;further illuminations on a reaction equation of titania defect formation,a tentative universal surface physical mode for the wet ability,a concept,amphiphobicity,and surface design were carried out after the author's previous introduction and proposal in the end of 1999.

The Investigation Of Prepare Condition For Micropores Membranes From Poly(Vinylidene Fluoride), Xu-Mei Ren, Feng Wu, Ying Bai, Hang-Jun Li, Xue Jie Huang

Journal of Electrochemistry

The micropores membranes from Poly (vinylidene fluoride) were prepared by the phase inversion process. The effects of the casting solution composition, exposure time prior to coagulation and temperature of the coagulation bath on properties of prepared membranes were investigated. For all prepared membranes an asymmetric structure, sometimes without a dense skin layer, was observed.

Studies On The Properties Of The Anodic Films Formed On Lead- Lanthanum And Lead-Samarium Alloys In Sulfuric Acid Solution, Hou Tian Liu, Chun Xuao Yang, Hai Heng Liang, Jiong Yang, Wei-Fang Zhou

Journal of Electrochemistry

AC voltammetry,linear sweep voltammetry,and cyclic voltammetry were applied to study the anodic corrosion of Pb,Pb 1.0at%La and Pb 1.0at%Sm electrodes in 4.5 mol·dm -3 H 2SO 4 solution (25 ℃).The experiment results show that samarium can inhibit the anodic corrosion of lead and decrease the impedance of anodic Pb(Ⅱ) film. Lanthanum can also decrease the impedance of the anodic Pb(Ⅱ)film, but the effect is smaller.

Adsorption And Oxidation Of Methanol On Pt And Sb, S Modified Pt Electrodes Using Cyclic Voltammetry And Eqcm, Guo-Liang Chen, Sheng-Pei Chen, Heng Lin, Xing-Hong Zheng, Shi-Gang Sun

Journal of Electrochemistry

The processes of adsorption and oxidation of methanol on Pt, Pt/Sb ad and Pt/S ad electrodes were studied by using cyclic voltammetry and electrochemical quartz crystal microba_lance (EQCM). The results demonstrated that the oxidation of methanol depends strongly on oxidation states of electrode surface. Sb adatoms on Pt surface can adsorb oxygen at relatively low potentials, and exhibit catalytic effects for methanol oxidation. In contrast to Pt electrodes, the oxidation peak potential of methanol in this case negatively shifted to about 130 mV. In a contrary, the oxidation of S adatoms consumes oxygen species of Pt electrode surface. As a …

Corrosion Of Steel In Sea-Bottom Mud Of Nothern China Sea Area, Gong-Yu Guo, Jing-Lei Zhang, Bao-Rong Hou, Fang-Ying Yang

Journal of Electrochemistry

Corrosion experiments of A 3, 16Mn, 20 # as well as ZCE36_225 steel were carried out in southern Bohai sea and Qingdao sea areas. The sea_bottom mud in southern Bohai sea area is the sandy mud and that in Qingdao sea area is pure beach sand. In this experiment, the compareing test of two modes with electric connected and non_electric connected modes was carried out. The experiment results showed that: 1) the corrosion rate of steel in sea_bottom mud has a strong relation with mud types. The corrosion rates of steels in pure beach sand are much higher than those …

The Research Of Organic Electrolyte Solutions For Li-Ion Batteries, Quang Chao Zhuang, Shan Wu, Wen Yuan Liu, Zhao-Da Lu

Journal of Electrochemistry

The characteristics of organic electrolyte solutions and its influences on the ion conductivity are summarized. The chemistry and electrochemistry of organic electrolyte solutions and characteristics of ordinary organic solvents are introduced. Progresses in studies of organic electrolyte solutions such as electrolyte salts, organic solvents, additives in recent years are reviewed, current situation of the studies of organic electrolyte solutions were also discussed.

New Progress Of Intrinsic Conducting Polymers' Application, Wan Chen, Cheng-Hao Liang, Yang Xie

Journal of Electrochemistry

As a kind of functional polymer, the intrinsic conducting polymer has the special chemical, electrochemical and optical properties. So it has wide application such as batteries, electromagnetic wave shielding, electroluminescent etc. Recent development and the problems of the intrinsic conducting polymers' application were briefly reviewed in this paper.

Research Progress On Proton Exchange Membranes Of Fuel Cells, Jing-Rong Yu, Dan-Min Xing, Fu-Qiang Liu, Jian-Guo Liu, Bao-Lian Yi

Journal of Electrochemistry

The proton exchange membrane fuel cells(PEMFC) use proton exchange membranes(PEM) as their electrolytes. The performance of the PEMFC is strongly dependent on the characteristics of the PEM. In this paper, the requirements of the PEM utilized in the PEMFC were analyzed. The per_fluorinated, partially fluorinated and non_fluorinated PEM were introduced respectively. The structures, preparation, properties of the various types of PEM and their applications in the PEMFC were also discussed in detail.

Electrosynthesis Of A New Electroactive Poly(2,2'-Diaminophenyloxydisulfide), Yu Zhi Su, Yan Wen Rao, Ye Yang, Mei-Bing Chen, Yin Ling Qiu, Yong-Hua Zhang, Ke Cheng Gong

Journal of Electrochemistry

A new electroactive poly(2,2' diaminophenyloxydisulfide) (PDAPD) was successfully synthesized from acetonitrile(AN)/tetrahydrofuran(THF)solutions containing the supporting electrolyte(LiClO 4)and the various kinds of acids(HCl,CF 3COOH,CCl 3COOH) on Pt electrode by consecutive cyclic voltammiry. The effects of the concentrations of supporting electrolyte(LiClO 4) and acid(HCl,CF 3COOH,CCl 3COOH) on electrodepositon of PDAPD film were investigated. The best experimental conditions for electrosynthesis of a highly electroactive conducting polymer film are that the concentrations are 0.1 mol/L and between 0.05 mol/L～0.5 mol/L,respectively for LiClO 4 and HCl.

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Aaa Task-4 Quarterly (September 1 – November 30, 2001) Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including HT- 9, EP 823 and 422. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these alloys will be evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. The extent and morphology of cracking of these alloys will further be evaluated …

Titanium Dioxide Photocatalytic Degradation Of Aliphatic Ethers And Their Primary Oxidation Products, Vivian Cruz

FIU Electronic Theses and Dissertations

Two studies were performed to obtain fundamental mechanistic information on the TiO₂ catalyzed degradation of organic substrates irradiated at 350 nm in dilute aqueous solutions under oxygenated conditions: (a) The photodecomposition of methyl tert-butyl ether (MTBE) and its intermediate products from β - oxidation, 2-methoxy-2-methylpropanol and 2-methoxy-2-methylpropanal. (b) The photodecomposition of two haloethers, bis-(2-chloroethyl) ether, and bis-(2-chloroisopropyl) ether. Controls were carried out throughout the two studies in the absence of light, and without the semiconductor in order to evaluate the role of photolysis.

The syntheses of proposed intermediate products, 2-methoxy-2-methylpropanol, 2-methoxy-2-methylpropanal, 2-methoxy-2-methylpropanoic acid, 2-chloroethyl formate, and 1-chloro-2-propyl acetate, …

Experimental And Modeling Studies Of Secondary Organic Aerosol Formation And Some Applications To The Marine Boundary Layer, Song Gao, Dean A. Hegg, Glendon Frick, Peter F. Caffrey, Louise Pasternack, Chris Cantrell, William Sullivan, John Ambrusko, Thomas Albrechcinski, Thomas W. Kirchstetter

Chemistry and Physics Faculty Articles

A series of controlled experiments were carried out in the Calspan Corporation's 600 m³environmental chamber to study some secondary organic aerosol formation processes. Three precursor-ozone systems were studied: cyclopentene-ozone, cyclohexene-ozone, and α-pineneozone. Additionally, SO₂ was added to the initial gas mixture in several instances and was likely present at trace levels in the ostensibly organic-only experiments. It was found that all three systems readily formed new submicron aerosols at very low reactant levels. The chemical composition of formed aerosols was consistent with some previous studies, but the yields of organic products were found to be lower in …

Sulfur Dioxide Uptake And Oxidation In Sea-Salt Aerosol, William Hoppel, Louise Pasternack, Peter F. Caffrey, Glendon Frick, James Fitzgerald, Dean A. Hegg, Song Gao, John Ambrusko, Thomas Albrechcinski

Chemistry and Physics Faculty Articles

Measurements of SO₂ and O₃ uptake by sea-salt and NaCl aerosol were made in a 600 m³environmental chamber by measuring the rate of SO₂ and O₃ depletion during nebulization of seawater and NaCl solutions. The experiments were carried out with starting relative humidity between 80% and 92%, with SO₂ concentrations between 35 and 60 ppb, and ozone concentrations between O and 110 ppb. For NaCl, no SO₂ or O₃uptake was observed. For sea-salt aerosol, uptake in the range of 0.21 and 1.2 millimoles of S per liter of (nebulized) seawater …

In-Cloud Oxidation Of So2 By O3 And H2o2: Cloud Chamber Measurements And Modeling Of Particle Growth, Peter F. Caffrey, William Hoppel, Glendon Frick, Louise Pasternack, James Fitzgerald, Dean A. Hegg, Song Gao, W. R. Leaitch, Nicole Shantz, Thomas Albrechcinski, John Ambrusko

Chemistry and Physics Faculty Articles

Controlled cloud chamber experiments were conducted to measure particle growth resulting from the oxidation of SO₂ by O₃ and H₂O₂ in cloud droplets formed on sulfuric acid seed aerosol. Clouds were formed in a 590 m³ environmental chamber with total liquid water contents ranging from 0.3–0.6 g m⁻³ and reactant gas concentrations <10 ppbv for SO₂ and H₂O₂ and <70 ppbv for O₃. Aerosol growth was measured by comparison of differential mobility analyzer size distributions before and after each 3–4 min cloud cycle. Predictions of aerosol growth were then made with a full microphysical cloud …

Particle Formation And Growth From Ozonolysis Of Α-Pinene, William Hoppel, James Fitzgerald, Glendon Frick, Peter F. Caffrey, Louise Pasternack, Dean A. Hegg, Song Gao, W. Richard Leaitch, Nicole Shantz, Chris Cantrell, Thomas Albrechcinski, John Ambrusko, William Sullivan

Chemistry and Physics Faculty Articles

Observations of particle nucleation and growth during ozonolysis of α-pinene were carried out in Calspan's 600 m³ environmental chamber utilizing relatively low concentrations of α-pinene (15 ppb) and ozone (100 ppb). Model simulations with a comprehensive sectional aerosol model which incorporated the relevant gas-phase chemistry show that the observed evolution of the size distribution could be simulated within the accuracy of the experiment by assuming only one condensable product produced with a molar yield of 5% to 6% and a saturation vapor pressure (SVP) of about 0.01 ppb or less. While only one component was required to simulate the …

Magnetic Ordering In An Organic Polymer, Andrzej Rajca, Jirawat Wongsriratanakul, Suchada Rajca

Andrzej Rajca Publications

We describe preparation and magnetic properties of an organic p-conjugated polymer with very large magnetic moment and magnetic order at low temperatures. The polymer is designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S = 2 and, cross-linking S = ½ modules, which permits large net S values for either ferromagnetic or antiferromagnetic exchange couplings between the modules. In the highly cross-linked polymer, an effective magnetic moment corresponding to an average S of about 5000 and slow reorientation of the magnetization by a small magnetic field …

Micromagnetics Simulation Of Deep-Submicron Supermalloy Disks, Scott L. Whittenburg, Ngocnga Dao, R. P. Cowburn

Chemistry and Biochemistry Faculty Publications

The results of recent micromagnetic simulations of deep submicron supermalloy disks are presented. A recent experimental measurement of the hysteresis and magnetic domain structure in supermalloy disks with diameters ranging from 55 to 500 nm and thickness ranging from 6 to 15 nm has been reported. Our micromagnetic simulations show remarkable agreement with the experimental hysteresis loops. The simulation results show that for thin or small diameter disks a single magnetic domain exists with all spins aligned. The hysteresis loop represents free rotation of these spins. For larger diameter disks or as the thickness increases the hysteresis loops change shape …

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

We examined stainless samples that were exposed to LBE in experiments conducted by the Russians, under contract to Los Alamos. We examined both corroded and uncorroded samples using the Scanning Electron Microscope (SEM), the Energy Dispersive X-Ray (EDAX) Spectroscopy, and the X-ray Photoelectron Spectrometer (XPS). We found that the surface of the corroded sample is covered by oxygen-containing compounds, presumably mostly iron oxide. In samples exposed for shorter times or lower temperatures, we found that some areas were covered by an oxide layer, and some areas was uncovered. We found that the level of Cr in the uncovered area is …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report August 16,2001- November 15, 2001, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application.

Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with very limited density. The transport of oxygen and corrosion products, their interaction and variation of corrosion/precipitation along the flow are not well understood.

The first subtask of this project involves using a …

Monte Carlo Simulation Of Homogeneous Binary Vapor–Liquid Nucleation: Mutual Enhancement Of Nucleation In A Partially Miscible System, S. Yoo, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Gibbs free energy of ij-cluster formation ΔG_ij is obtained via the relation n_ij=Ne^{-ΔG_ij /k_BT}, where N is the number of molecules in the system, T is temperature, and kB is the Boltzmann constant. The saddle point on the free energy surface ΔG_ij versus i and j provides a measure of the activation barrier to nucleation ΔG *. A statistical mechanical formula of ΔG_ij is derived based on the physical-cluster theory of nucleation, and from which a molecular interpretation of ΔG_{ij …}

Synthesis Of A New Hollandite-Type Manganese Oxide With Framework And Interstitial Cr(Iii), Stanton Ching, Peter F. Driscoll, Katarzyna S. Krukowska, Michael R. Marvel, Steven L. Suib

Chemistry Faculty Publications

Hollandite with Cr(III) in both tunnel and framework sites has been prepared hydrothermally from layered manganese oxide precursors.

Poly Millennial 2000 Hilton Waikoloa Villages, Hawaii, December 9-13, 2000, Otto Vogl, William Daly

Otto Vogl

No abstract provided.

Micromagnetics Simulation Of Deep-Submicron Supermalloy Disks, Scott Whittenburg

Chemistry Faculty Publications

The results of recent micromagnetic simulations of deep submicron supermalloy disks are presented. A recent experimental measurement of the hysteresis and magnetic domain structure in supermalloy disks with diameters ranging from 55 to 500 nm and thickness ranging from 6 to 15 nm has been reported. Our micromagnetic simulations show remarkable agreement with the experimental hysteresis loops. The simulation results show that for thin or small diameter disks a single magnetic domain exists with all spins aligned. The hysteresis loop represents free rotation of these spins. For larger diameter disks or as the thickness increases the hysteresis loops change shape …

Variational Transition State Theory Evaluation Of The Rate Constant For Proton Transfer In A Polar Solvent, Robin P. Mcrae, Gregory K. Schenter, Bruce C. Garrett, Zoran Svetlicic, Donald G. Truhlar

Chemistry and Biochemistry Faculty Publications

Variational transition state theory (VTST) is used to calculate rate constants for a model proton transfer reaction in a polar solvent. We start from an explicit description of the reacting solute in a solvent, and we model the effects of solvation on the reaction dynamics by a generalized Langevin equation (GLE) for the solute. In this description, the effects of solvation on the reaction energetics are included in the potential of mean force, and dynamical, or nonequilibrium, solvation is included by solvent friction. The GLE solvation dynamics are approximated by a collection of harmonic oscillators that are linearly coupled to …

Ca4Iro6, Ca3Mgiro6 And Ca3Zniro6, Matthew J. Davis, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Single crystals of tetracalcium iridium hexaoxide, Ca₄IrO₆, tricalcium magnesium iridium hexaoxide, Ca₃MgIrO₆, and tricalcium zinc iridium hexaoxide, Ca₃ZnIrO₆, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The three compounds are isostructural and adopt the K₄CdCl₆ structure type, comprised of chains of alternating face-shared [CaO₆], [MgO₆] or [ZnO₆] trigonal prisms and [IrO₆] octahedra, surrounded by columns of Ca²⁺ ions.

Formula: Ca₄IrO₆, Ca_3.34Mg_0.66IrO₆ and …

A Dipolar Coupling Based Strategy For Simultaneous Resonance Assignment And Structure Determination Of Protein Backbones, Fang Tian, Homayoun Valafar, James H. Prestegard

Faculty Publications

A new approach for simultaneous protein backbone resonance assignment and structure determination by NMR is introduced. This approach relies on recent advances in high-resolution NMR spectroscopy that allow observation of anisotropic interactions, such as dipolar couplings, from proteins partially aligned in field ordered media. Residual dipolar couplings are used for both geometric information and a filter in the assembly of residues in a sequential manner. Experimental data were collected in less than one week on a small redox protein, rubredoxin, that was 15N enriched but not enriched above 1% natural abundance in 13C. Given the acceleration possible with partial 13C …

Dopamine Adsorption At Surface Modified Carbon-Fiber Electrodes, Bradley Bath, Heidi Martin, R. Mark Wightman, Mark Anderson

Mark R. Anderson

Fast-scan cyclic voltammetry at high repetition rates was used to characterize adsorptive properties of dopamine (DA) at native and modified carbon-fiber microelectrode surfaces. Disk electrodes were fabricated from Thornel P55 fibers, and cylindrical electrodes, from Thornel T650 fibers. Their surfaces were modified by physisorption of 2,6-anthraquinone disulfonic acid (2,6-AQDS) or chemisorption of 4-carboxyphenyl or catechols. Chemisorption was accomplished via electrochemical reduction of diazonium salts. The degree of DA adsorption and its oxidation kinetics were found to vary for the two types of native carbon fiber electrodes and with the different chemical overlayers on the carbon surfaces. 2,6-AQDS measurably increased DA …

The Tetramethylpiperidinyl-1-Oxide Anion (Tmpo-) As A Ligand In Lanthanide Chemistry: Synthesis Of The Per(Tmpo-) Complex [(Onc5h6me4)2sm(Μ-Onc5h6me4)]2, William J. Evans, Jeremy M. Perotti, Robert J. Doedens, Joseph W. Ziller

Chemistry and Physics Faculty Articles

(C₅Me₅)₃Sm reacts with the free radical 2,2,6,6-tetramethylpiperidinyl-1-oxy (TMPO) to form (C₅Me₅)₂ and the per nitroxide [(η¹-ONC₅H₆Me₄)₂ Sm(μ-η¹∶η²-ONC₅H ₆Me₄)]₂

Simultaneous Determination Of Enantiomers Of Structurally Related Anticholinergic Analogs In Human Serum By Liquid Chromatography–Electrospray Ionization Mass Spectrometry With On-Line Sample Cleanup, Vladimı́R Čápka, Yan Xu

Chemistry Faculty Publications

Trihexyphenidyl, biperiden and procyclidine are anticholinergic drugs produced as racemates for the treatment of Parkinson’s disease. This paper describes a simple and sensitive LC–MS method for the simultaneous determination of these compounds in human serum. An on-line sample clean-up procedure was used, where serum samples were directly injected into a “restricted-access media” pre-column. After the exclusion of the serum proteins, the drug molecules were eluted to a β-cyclodextrin analytical column for chiral separation. The quantitation was done by electrospray ionization MS using diphenidol as an internal standard. The method developed has limits of detection of 1 ng/ml, at least two-orders-of-magnitude …