Physical Sciences and Mathematics Commons^™

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.

Spectroellipsometric Studies On Electrochemistry And Its Application, Zongqing Huang, Shengtao Zhang, Shangfen Xie, Changguo Chen, Yuru Yang, Wei Zhu

Journal of Electrochemistry

Ellipsometric measurements are often extremely sensitive to the presence of very thin surface layers,to changes in their thickness(or coverage),and to changes in surface topography at an atomic scale.These characteristics make the use of ellipsometry for electrochemical studies particularly attractive.The ellipsometric studies on electrochemistry and its applications carried out in the Electrochemical Laboratory of Chongqing University are reviewed briefly: 1)The studies on electrochemistry of classical ellipsometry: 2)The new function V op suggested by the authors. 3)The applications of new approcaches with new function V op suggested by the authors.

Deactivation Of Nickel Oxide/Hydroxide To Electrooxidation Of H 2po - 2 Anions On Nickel Electrodes In Alkaline Solutions, Taixiang Jiang, Huihuang Wu

Journal of Electrochemistry

Electrooxidation of hypophosphite anions on polycrystalline nickel in alkaline solutions has been investigated by cyclic voltammetry and open circuit potential measurements.The results are explained based on the mechanism that the first step of hypophosphite oxidation is the adsorption of hypophosphite ions on nickel,followed by the homolysis of its hydrogen bond with the formation of radicals.The oxidation of hypophosphite on nickel in alkaline medium occurs at lower potentials between ca.-0.8 V—-1.1 V(SCE)and phosphite ion is the only oxidation product.There is no indication of hypophosphite oxidation at higher potentials.Severe deactivation of the surface occurs when the nickel surface is covered with surface …

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 …

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 …

Direct Electrolysis Of Seawater On Conducting Film For Microbial Anticorrosion 1. Simulation And Measurement Technique, Weiling Hu, Lingling Wu, Jing Zhou, Jingxin Li, Jin Luo, Zhonghua Lin

Journal of Electrochemistry

Based on the electrochemical micro probe and the weak signal detection technique, simulated test and measurement system were set up by the use of four_electrode cell(including a micro electrode), bipotentiostat, lock_in amplifier and three_dimensional micro manipulating device. Based on the system, the micrometer scale concentration distribution of trace hypochlorite, which is produced by direct electrolysis of seawater on the conducting film for preventing microbial corrosion has been obtained for the first time. Both relationships between concentration of hypochlorite and its reduction current, which is termed an working curve, and between the reduction current of hypochlorite and measured time are reported.

A Study Of The Corrosion On Bronze, Hongfan Zhu, Hao Zhou

Journal of Electrochemistry

The bronze is the treasure in chinese metallic antique, which was typified by product in Shang_Zhou period (three thousands years ago). Because of corrosion, archaeological messages,such as inscription and pattern on the surface of bronze, would be damaged then the value of bronze antique decreased. The bronze disease is a common disease which forms powdery rust on the surface of bronze in atmospheric environment, the powdery rust emerge from under incrusted rust, then spreads, and eventually leads to bronze damaged. This paper investigates the bronze disease. According to the chemical and electrochemical tests in simulated occluded cell, the variation in …

A Study Self_Passivation Of Passivie Film Of Stainless Steel In Vinylon Aldehyde Solution, Sifu Hu, Chuanbi Xu, Zhuqiu Cheng

Journal of Electrochemistry

Properties of self_passivation for the anodic passive film of 1Cr18Ni9Ti and the firsthand passive film of SUS 36 stainless steel in vinylon aldehyde solution(H 2SO 4(240 g/L)+Na 2SO 4(70 g/L)+HCHO(25 g/L)+[Fe 3+ ](35.4 mg/L)+[Cl -](240 mg/L) at 70 ℃ were studied by galvanostatic and potentiostatic polarization mesurements. The effects of compponents of vinylon aldehyde solution, i.e. Fe 3+ and Cl -, on the passivation behaviours of stainless steel have also been investigated. The experimental results showed there is a conversion zone of the active/passive state if the area ratio of active/passive state on these stainless steel attained to a critical …

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 …

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 …

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 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.

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.

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 …

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.

Almost Periodic Factorization Of Certain Block Triangular Matrix Functions, Ilya M. Spitkovsky, Darryl H. Yong

All HMC Faculty Publications and Research

Let

where , and . For rational such matrices are periodic, and their Wiener-Hopf factorization with respect to the real line always exists and can be constructed explicitly. For irrational , a certain modification (called an almost periodic factorization) can be considered instead. The case of invertible and commuting , was disposed of earlier-it was discovered that an almost periodic factorization of such matrices does not always exist, and a necessary and sufficient condition for its existence was found. This paper is devoted mostly to the situation when is not invertible but the commute pairwise (). The complete description is …

Divisible Tilings In The Hyperbolic Plane, Sean A. Broughton, Dawn M. Haney, Lori T. Mckeough, Brandy M. Smith

Mathematical Sciences Technical Reports (MSTR)

We consider triangle-quadrilateral pairs in the hyperbolic plane which "kaleidoscopically" tile the plane simultaneously. In this case the tiling by quadrilaterals is called a divisible tiling. All possible such divisible tilings are classified. There are a finite number of 1,2, and 3 parameter families as well as a finite number of exceptional cases.

Switching Properties Of Self-Assembled Ferroelectric Memory Cells, M. Alexe, Alexei Gruverman, C. Harnagea, N. D. Zakharov, A. Pignolet, D. Hesse, J. F. Scott

Alexei Gruverman Publications

In this letter, we report on the switching properties of an ordered system of Bi₄Ti₃O₁₂ ferroelectric memory cells of an average lateral size of 0.18 μm formed via a self-assembling process. The ferroelectricity of these cells has been measured microscopically and it has been demonstrated that an individual cell of 0.18 μm size is switching. Switching of single nanoelectrode cells was achieved via scanning force microscopy working in piezoresponse mode.

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.

Mathematical Modelling Of Extracellular Matrix Dynamics Using Discrete Cells: Fiber Orientation And Tissue Regeneration, J. C. Dallon, J. A. Sherratt, P. K. Maini

Faculty Publications

Matrix orientation plays a crucial role in determining the severity of scar tissue after dermal wounding. We present a model framework which allows us to examine the interaction of many of the factors involved in orientation and alignment. Within this framework, cells are considered as discrete objects, while the matrix is modeled as a continuum. Using numerical simulations, we investigate the effect on alignment of changing cell properties and of varying cell interactions with collagen and fibrin.

The Effect Of Abundance Variations On Estimates Of The Densities Of Broad-Line Region Clouds In Quasars, Stephanie A. Snedden, C. Martin Gaskell

C. Martin Gaskell Publications

There has been a long-standing discrepancy between the densities deduced from studies of the variability of quasar emission lines and those inferred from standard photoionization analyses. We have found that the higher metal abundances now believed to be present in most quasars lead to the higher densities being predicted by photoionization models. We explain why this is so.

The Galactic Center Isolated Nonthermal Filaments As Analogs Of Cometary Plasma Tails, Steven N. Shore, Ted La Rosa

Faculty Articles

We propose a model for the origin of the isolated nonthermal filaments observed at the Galactic center based on an analogy to cometary plasma tails. We invoke the interaction between a large-scale magnetized galactic wind and embedded molecular clouds. As the advected wind magnetic field encounters a dense molecular cloud, it is impeded and drapes around the cloud, ultimately forming a current sheet in the wake. This draped held is further stretched by the wind flow into a long, thin filament the aspect ratio of which is determined by the balance between the dynamical wind and amplified magnetic field pressures. …

Two New Topologically Ordered Glass Phases Of Smectics Confined In Anisotropic Random Media, Brad Jacobsen, Karl Saunders, Leo Radzihovsky, John Toner

Physics

Smectics in strained aerogel exhibit two new glassy phases. The strain both ensures the stability of these phases and determines their nature. One type of strain induces an “ XY Bragg glass,” while the other creates a novel, triaxially anisotropic “ m = 1 Bragg glass.” The latter exhibits anomalous elasticity, characterized by exponents that we calculate to high precision. We predict the phase diagram, and numerous other experimentally observable scaling laws, for the system.

Computational Complexity For Continuous Time Dynamics, Hava Siegelmann, Asa Ben-Hur, Shmuel Fishman

Hava Siegelmann

Dissipative flows model a large variety of physical systems. In this Letter the evolution of such systems is interpreted as a process of computation; the attractor of the dynamics represents the output. A framework for an algorithmic analysis of dissipative flows is presented, enabling the comparison of the performance of discrete and continuous time analog computation models. A simple algorithm for finding the maximum of n numbers is analyzed, and shown to be highly efficient. The notion of tractable (polynomial) computation in the Turing model is conjectured to correspond to computation with tractable (analytically solvable) dynamical systems having polynomial complexity.

Electrical Transport, Magnetism, And Spin-State Configurations Of High-Pressure Phases Of Fes, Takele Seda, G. R. Hearne

Physics & Astronomy

Both the nature of the electrical transport and magnetism of high-pressure phases of FeS have been elucidated in relation to the spin-state configuration of Fe. This has been achieved by combined ⁵⁷FeMössbauer spectroscopy and resistance measurements on samples pressurized in miniature gem-anvil pressure cells to ∼12 GPa in the range 300–5 K. Hexagonal FeS in the range 3–7 GPa exhibits magnetic nonmetallic behavior, whereas monoclinic FeS beyond ∼7 GPa is diamagnetic and nonmetallic. This is compelling experimental evidence to show that, along the room-temperature isotherm, hexagonal FeS has thermally activated charge carriers and a high-spin magnetic-electronic configuration, whereas monoclinic …

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.

Temporal Probabilistic Logic Programs, Alex Dekhtyar, Michael I. Dekhtyar, V. S. Subrahmanian

Computer Science and Software Engineering

There are many applications where the precise time at which an event will occur (or has occurred) is uncertain. Temporal probabilistic logic programs (TPLPs) allow a programmer to express knowledge about such events. In this paper, we develop a model theory, fixpoint theory, and proof theory for TPLPs, and show that the fixpoint theory may be used to enumerate consequences of a TPLP in a sound and complete manner. Likewise the proof theory provides a sound and complete inference system. Last, but not least, we provide complexity results for TPLPs, showing in particular, that reasonable classes of TPLPs have polynomial …