bluuebunny/crossref_metadata_2025 huggingface dataset:
Memfractance: A Mathematical Paradigm for Circuit Elements with Memory
Authors: Abdelouahab Mohammed-Salah , Lozi René , Chua Leon
Published: October 2014

Memristor, the missing fourth passive circuit element predicted forty years ago by Chua was recognized as a nanoscale device in 2008 by researchers of a H. P. Laboratory. Recently the notion of memristive systems was extended to capacitive and inductive elements, namely, memcapacitor and meminductor whose properties depend on the state and history of the system. In this paper, we use fractional calculus to generalize and provide a mathematical paradigm for describing the behavior of such elements with memory. In this framework, we extend Ohm's law to the generalized Ohm's law and prove it.
Cycle Lengths and Correlation Properties of Finite Precision Chaotic Maps
Authors: Öztürk İsmail , Kiliç Recai
Published: October 2014

This paper investigates cycle and transient lengths of spatially discretized chaotic maps with respect to different initial condition values. By investigating cycle lengths and their correlation properties using fixed point arithmetic, it is observed that for different initial condition values only a limited number of cycles occur for each resolution and rounding type. Additionally, it is seen that cycles with the same length are actually identical due to intersections between pseudo trajectories. The drawbacks of this situation are demonstrated for chaos based cryptosystems that use initial conditions as key. It is shown that highly correlated outputs for different initial conditions cause serious security vulnerabilities, although the statistical tests indicate otherwise. Finally, correlations in the perturbed systems are discussed.
Chaos for Cosine Operator Functions Generated by Shifts
Authors: Chen Chung-Chuan
Published: October 2014

Let 1 ≤ p < ∞. We give the sufficient and necessary condition for cosine operator functions, generated by bilateral weighted shifts on ℓp(ℤ), to be chaotic. Moreover, such a cosine operator function is chaotic if, and only if, its weighted shift is chaotic.
Bifurcations Near the Weak Type Heterodimensional Cycle
Authors: Liu Xingbo
Published: October 2014

The aim of this paper is to show the bifurcation phenomena near the weak type heterodimensional cycle when the orbit flip and inclination flip occur simultaneously in its nontransversal heteroclinic orbit. With the aid of a suitable local coordinate system, the Poincaré map is constructed. By means of the bifurcation equations, the persistence of heterodimensional cycles, the coexistence of the heterodimensional cycle and periodic orbits or homoclinic orbits, and the existence of bifurcation surfaces of homoclinic orbits or the periodic orbits are discussed under small perturbations. Moreover, an example is given to show the existence of the system which has a heterodimensional cycle with orbit flip and inclination flip.
New Approach to Modeling Symbiosis in Biological and Social Systems
Authors: Yukalov V. I. , Yukalova E. P. , Sornette D.
Published: October 2014

We suggest a novel approach to treating symbiotic relations between biological species or social entities. The main idea is the characterization of symbiotic relations of coexisting species through their mutual influence on their respective carrying capacities, taking into account that this influence can be quite strong and requires a nonlinear functional framework. We distinguish three variants of mutual influence, representing the main types of relations between species: (i) passive symbiosis, when the mutual carrying capacities are influenced by other species without their direct interactions; (ii) active symbiosis, when the carrying capacities are transformed by interacting species; and (iii) mixed symbiosis, when the carrying capacity of one species is influenced by direct interactions, while that of the other species is not. The approach allows us to describe all kinds of symbiosis, mutualism, commensalism, and parasitism within a unified scheme. The case of two symbiotic species is analyzed in detail, demonstrating several dynamical regimes of coexistence, unbounded growth of both populations, growth of one and elimination of the other population, convergence to evolutionary stable states, and everlasting population oscillations. The change of the dynamical regimes occurs by varying the system parameters characterizing the destruction or creation of the mutual carrying capacities. The regime changes are associated with several dynamical system bifurcations.
Can We Obtain a Reliable Convergent Chaotic Solution in any Given Finite Interval of Time?
Authors: Liao Shijun
Published: October 2014

Generally, it is difficult to obtain convergent chaotic solution in an arbitrarily given finite interval of time. Some researchers even believe that all chaotic responses are simply numerical noise and have nothing to do with solutions of differential equations. However, using 1200 CPUs of the National Supercomputer TH-A1 at Tianjin and a parallel integration algorithm of the so-called "Clean Numerical Simulation" (CNS) based on the 3500th-order Taylor expansion and data in 4180-digit multiple precision, one can obtain reliable convergent chaotic solution of the Lorenz equation in a rather long time interval [0,10 000]. This supports Lorenz's optimistic viewpoint [Lorenz 2008] that "numerical approximations can converge to a chaotic true solution throughout any finite range of time". It also supports Tucker's proof [Tucker 1999, 2002] for the famous Smale's 14th problem that the strange attractor of the Lorenz equation indeed exists.
PROLIFERATIVE EFFECT OF PLATELET-RICH FIBRIN ON CANINE BONE MARROW-DERIVED STROMAL CELLS
Authors: Chen Kuan-Sheng , Chien Kuo-Chieh , Huang Young-San , Chang Cicero Lee-Tian , Chang Shih-Chieh
Published: October 2014

Platelet-rich fibrin (PRF) has been widely used to accelerate wound and bone healing in human patients. The aim of the study was to establish a canine bone marrow-derived stromal cell (BMSC) culture system and to investigate the effect of PRF on these cells. PRF was prepared using density gradient centrifugation and BMSCs were obtained from the fracture sites of 23 dogs during surgical procedures and individually analyzed. Canine BMSCs were either cultured in osteogenic medium or cultured with/without the presence of PRF. Canine BMSCs expressed similar surface antibodies to mesenchymal stem cells and were able to undergo osteogenic differentiation in osteogenic medium. PRF stimulated proliferation of BMSCs, but PRF alone had no effect on osteogenic differentiation. This study provides useful information about the proliferation effect of PRF, and the canine culture system in the presence of osteogenic medium allows the differentiation of BMSCs in vitro. These results may benefit future application in the clinic.
Understanding and Predicting the Lithium Dendrite Formation in Li-Ion Batteries: Phase Field Model
Authors: Zhang Hao-Wei , Liu Zhe , Liang Linyun , Chen Lei , Qi Yue , Harris Stephen J , Lu Peng , Chen Long-Qing
Published: October 2014

Lithium (Li) dendrite formation compromises the reliability of Li-metal batteries, either because dendrite pieces lose electrical contract or growing dendrite penetrates the separator and leads to internal short-circuiting. In this paper, a nonlinear phase-field model is formulated to predict Li dendrite formation at the electrode/electrolyte interface. The phase field evolves by electrochemical reaction of which the rate depends on nonlinearly the thermodynamics driving force involving overpotential and ion concentration. A revised Poisson-Nesters-Planck Equation is further solved for ionic transport and local overpotential variation. The model is validated by 1-D fields distribution involving phase field, Lithium ion concentration and electrostatic potential. The 2-D tree-type lithium dendrite during Li deposition was produced if anisotropic surface energy is assumed. Finally, the 2D morphological evolution under different electrochemical conditions specified by the charging current density, and the anisotropy of surface energy was discussed.
The Effect of Battery Potential and Charge Rate on the Decomposition Reaction on the Anode Electrode of Lithium Ion Polymer Battery
Authors: Agubra Victor , Fergus J. W. , Fu Rujian , Choe Song-yul
Published: October 2014

The breakdown of the protective solid electrolyte interface (SEI) layer on the anode electrode can initiate further electrolyte decomposition reaction and result in the formation of a non-uniform layer of electronically insulating reaction products on the graphite particles. The results from this study indicated that raising the state of charge (SOC) increased the rate of the electrolyte decomposition side reaction to form a thick deposit layer. The deposit surface layer formed at the electrode/electrolyte interface increased the interfacial charge transfer resistance and rise in the overall batteries impedance. A direct correlation between the capacity fade during cycling and the deposit layer growth was established. Analysis of the anode and the deposit layer showed an increasing amount of lithium in the deposit layer as well as “trapped” lithium in the graphite crystal structure as the batteries were aged at higher SOC.
Electroless Displacement Deposition of Noble Metal on Silicon Powder for Recovering from Urban Mines
Authors: Fukuda Kenji , Fukumuro Naoki , Sakamoto Susumu , Yae Shinji
Published: October 2014

We developed a simple recovery method of all noble metals from aqueous solutions by adding silicon (Si) powder and fluoride. This method is expected to be low-cost, because the Si powder and the fluoride solution can be supplied from semiconductor industries, such as the sawdust Si of wafering or dicing and the waste hydrofluoric acid solution of wafer cleaning or etching. In this study, we investigated the recovery of noble metals using a low-toxic agent instead of a toxic hydrofluoric acid, or sawdust Si powder. This method can recover noble metals using ammonium fluoride or sodium fluoride. The recovery rate with sawdust Si is as high as that using pure Si powder. We found that the recovery of noble metals by this method from aqueous solutions including aqua regia is also possible.
Contact Resistance Measurements for Electrodes on Silicon Prepared by Autocatalytic Electroless Metallization Using Metal Nanoparticles
Authors: Orita Yukiko , Atsushiba Hiroyuki , Enomoto Masato , Kimura Toshihiko , Fukumuro Naoki , Takagami Hidenori , Kato Kazuhiko , Sakamoto Susumu , Hirata Masaharu , Yae Shinji
Published: October 2014

Recently, we reported on autocatalytic electroless metallization of silicon using gold nanoparticles. This technology is expected to be a useful, low-cost, and reliable method to form electrodes on silicon for several devices, such as solar cells and power devices. For the fabrication of electrodes, it is important that the resistance, consisting of the sheet resistance of the metal patterns and the contact resistance between the metal and silicon, is low. In this study, we measure the contact resistance of metal electrodes on silicon prepared by autocatalytic electroless metallization using gold nanoparticles. The transfer length method is suitable to evaluate the contact resistance between electrolessly plated nickel-phosphorus alloy thin films and silicon. The values obtained for the contact resistivity decrease as the film thickness increases from 0.5 to 2.3 µm. This decrease is caused by the decrease of the sheet resistance of the metal films. Reliable values for the contact resistivity were determined to be 0.9 and 1.2 mΩ·cm2 for p+- and n+-doped wafers, respectively. The contact resistivity depends on the gold nanoparticle coverage.
Analytical Modeling of PEM Fuel Cell Gas Diffusion Layers Deformation under Compression: Part 1 - Linear Behaviour Region
Authors: Norouzifard Vahid , Bahrami Majid
Published: October 2014

In the Proton exchange membrane PEM fuel cell stack, transport characteristics of the porous gas diffusion layer (GDL) change due to the GDL microstructural parameters variation in a result of compressive loading. GDL provides mechanical support for the membrane assembly against the compressive loads imposed by bipolar plates. In the compressive loads more than a critical pressure, GDL has a linear mechanical behaviour and its compressive modulus reaches a constant value. Using unit cell approach and assuming a simplified geometry for the complex and random microstructure of the GDL, a new mechanistic model is developed that can accurately predict the mechanical behaviour of GDL. A comparison between the present model and the GDL stress-strain data shows that the model can predict accurately the mechanical behaviour of the GDL material. The nonlinear behaviour of GDL will be addressed in the second part of this study.
Impact of MPL Thickness on Water Management of PEMFC by Synchrotron X-ray Radiography
Authors: Lee Jongmin , Yip Ronnie , Antonacci Patrick , Ge Nan , Kotaka Toshikazu , Tabuchi Yuichiro , Bazylak Aimy
Published: October 2014

Synchrotron X-ray radiography was utilized to visualize a miniature fuel cell with an active area of 0.48 cm2 at an effective spatial resolution of 10 μm and 3 seconds per frame. Water in GDLs with MPL thicknesses of 0, 50, 100, 150 μm and 50 μm without a macro-substrate was quantified while the cell was operated at 0.5, 1.2 and 2.0 A/cm2. The presence of MPL significantly reduced water content at the interface between the catalyst and GDL. The thickness of MPL had trivial impact on water morphology in the GDL. In the perspective of water management, the GDL consisting of MPL without a macro-substrate can be effective as it produced the least amount of water.
The Carbon/Iodide Interface in Protic Ionic Liquid Medium for Application in Supercapacitors
Authors: Skowron Piotr , Frackowiak Elzbieta , Béguin François
Published: October 2014

Organic and inorganic iodides dissolved in protic ionic liquid (PIL) were used as source of pseudocapacitance at the activated carbon (AC) electrode/electrolyte interface. The organic iodide solutions were 0.25 mol·L-1 triethylammonium (protic) or tetraethylammonium (aprotic) iodide in triethylammonium bis(trifluoromethane)sulfonimide (PIL) and the inorganic ones 0.2 mol·L-1 potassium or lithium iodides in the same PIL. Experiments in two-electrode AC/AC cells with a silver pseudo-reference electrode demonstrate that the carbon/iodide interface in PIL undergoes redox reactions at around +0.6 V vs. Ag at the positive electrode whatever the iodide solution. The best capacitance properties were given by the KI solution, which allows operating up to 2.0 V with high capacitance value of 189 F·g-1 and 95% efficiency. Adding organic iodides to PIL resulted in a decrease of voltage from 2.4 V to 1.5 V, but still high capacitance values of 164 F·g-1 and 151 F·g-1 were observed for the protic and aprotic iodides, respectively.
Application of a Thermodynamic Model for Charged Interfaces to Lipid Membranes
Authors: Kobrak Mark Nicholas , Babatunde Kunle
Published: October 2014

We have previously [M. N. Kobrak, J. Phys.: Cond. Matt. 25 095006 (2013)] presented a thermodynamic model describing the relationship between the ionic strength of an electrolyte, the morphology of an interface with which it is in contact, and the distribution of ions within the system. We have shown that in some circumstances, the ionic strength of an electrolyte solution confined within a pore can be different from that of a macroscopic reservoir in which it is in contact. We apply the same model to electrolyte solutions enclosed by charged lipid bilayers, and show that the effect may be significant for small, unilamellar vesicles. However, the results also indicate that the effect will not be significant for biological systems in general.
Analytical Quality Solid-State Composite Reference Electrode and Electrochemical Platform
Authors: Sokalski Tomasz , Granholm Kim , Mousavi Zekra , Lewenstam Andrzej
Published: October 2014

A new type of all-solid-state reference electrodes based on a polymer/inorganic salt composite was designed, prepared, and characterized. Both a chemical polymerization method and an injection molding method were used for fabricating those novel electrodes. A rigorous testing procedure was used to reveal possible influence of pH, solution composition, the concentrations, and mobility of ions on the electrode response. The tests demonstrated the insensitivity of the electrodes to the matrix effects, excellent stability of the potential readings, and significantly reduced leakage of inorganic salt. It was shown that composite reference electrodes were on par or better in the performed tests than high-quality commercial reference electrodes. The reference electrodes described here are of analytical quality allowing for continuous, prolonged, and intensive usage. The performance of the reference electrode in demanding matrices such as environmental and biological samples was studied. This concept was further extended to produce the solid state electrochemical platform.
Application of Fluorescence Correlation Spectroscopy in the Characterization of Particle Size Distributions of Colloidal Silica Abrasives Used in Chemical-Mechanical Planarization
Authors: Jacobson Lauren M. , Turner Daniel K. , Rawat Ashwani K. , Carver Colin T. , Tripahi Abhinav , Moinpour Mansour , Remsen Edward E.
Published: October 2014

Particle size distribution (PSD) analysis of colloidal silica abrasives employed in chemical-mechanical planarization slurries is demonstrated using fluorescence correlation spectroscopy (FCS). FCS allows a quantitative determination of the PSD for a dispersion of abrasive silica particles through fluorescence measurements of a dye, Rhodamine 110 (R110), adsorbed to the particles. Analysis of the autocorrelation function (ACF) of the fluorescence intensity fluctuations from R110-dyed silica confirms the presence of the adsorbed dye on the particles. Application of the method of histograms to the ACF yields a detailed analysis of the shape of the PSD for silica particle dispersions. FCS is shown to reliably measure the hydrodynamic diameter of silica particles less than 20 nm in mean size, and at particle concentrations which are too dilute for PSD analysis using a widely applied method for this purpose, dynamic light scattering.
Comparative Study of the Power Performance for Advanced Li-Ion Capacitors with Various Carbon Anodes
Authors: Cao Wanjun , Zheng Junsheng , Adams Daniel , Zheng Jim P.
Published: October 2014

In recent years, an increased attention has been focused on Li-ion capacitors (LICs) which are high power hybrid devices. Various carbon materials (hard carbon (HC), soft carbon (SC) and graphite) have been investigated for use as the negative electrodes for LICs. The rate capabilities are compared by half cells with carbon anode as working electrode and lithium foil as counter electrode, and by LIC full cells with test current density up to 20 mA cm-2. It is found that the LIC with HC at 20 mA cm-2 could be maintained up to 72.5% of that at 0.5 mA cm-2, which is the best power performance among all the carbon materials. The Scanning electron microscopy (SEM) images, surface area and the pore size distribution are also studied and compared for the various carbon anode materials.
Photoelectrochemical Water Splitting on Hydrogen Modified Titanium Oxide (HM-n-TiO2) Thin Film Electrode
Authors: Frites Mourad , Khan Shahed U.M
Published: October 2014

Hydrogen modified titanium oxide (HM-n-TiO2) thin films were synthesized by thermal oxidation of Ti metal substrate. The hydrogenation of n-TiO2 was carried out electrochemically under cathodic polarization at −1.6 V vs SCE in 2.5 KOH electrolyte under dark condition. The photoactivity of HM-n-TiO2 thin films was assessed by measuring the rate of the water splitting reaction in terms of photocurrent density, J
p (mA cm-2) under solar simulated light. The HM-n-TiO2 photoelectrodes exhibited a four-fold enhancement in their photocatalytic activity compared to n-TiO2 prior to hydrogenation. The HM-n-TiO2 photoelectrodes were characterized using X-ray diffractions and the change in the valence band induced by the hydrogenation of n-TiO2 was examined by XPS measurements.
PEMFC Contamination - Fundamentals and Outlook
Authors: St-Pierre Jean , Angelo Michael , Bethune Keith , Ge Junjie , Higgins Scott , Reshetenko Tatyana V. , Virji Maheboob B.V. , Zhai Yunfeng
Published: October 2014

Contamination of proton exchange membrane fuel cells is coming to the forefront as commercialization activities multiply and fuel cell systems are confronted to field conditions away from the controlled laboratory environment. The recent progress achieved in understanding the disruptive effects of contaminants is reviewed. The analysis is focused on contaminant effects, contaminant sources, mechanisms, mitigation strategies and knowledge gaps in all these areas.
Application of the Transmission Line EIS Model to Fuel Cell Catalyst Layer Durability
Authors: Reid O'Rian O. , Saleh Farhana Sultana , Easton E. Bradley
Published: October 2014

We have recently demonstrated that the inclusion of electrochemical impedance spectroscopy (EIS) into accelerated stress tests (AST) can provide a wealth of information about the modes of degradation occurring within a fuel cell catalyst layer. In those reports we have used half-cell techniques to validate the interpretation of the transmission line model for durability studies. Here, we have performed AST with membrane-electrode assemblies in fuel cell and applied EIS diagnostics to verify the usefulness of this technique in durability testing.
Dissolved Hydrogen Voltammetric Probe and Its Application for Photosynthetic Bacterial Hydrogen Production Rate Evaluation
Authors: Zlatev Roumen , Stoytcheva Margarita , Medina Pablo Alberto Romero , Reyes Ana Luisa , Magnin Jean-Pierre
Published: October 2014

A 3-electrode probe having a construction similar to the Clark type oxygen probe was developed, elaborated, and characterized as a dissolved hydrogen sensor. A thin plastic membrane allowing the hydrogen diffusion into the sensor prevents the interference of the determined solution composition. The sensors analytical characteristics such as LOD, sensitivity, and linear response concentration range were determined employing an electrochemical hydrogen generator producing dissolved hydrogen which concentrations were calculated by the Faraday’s law application. The sensor characterization results are presented and discussed together with the results obtained from its application for real time determination of the rate of hydrogen production in 10 mL reactors by the variety IR3 of the photosynthetic strain Rhodobacter Capsulatus.
Enzyme-Metal Oxide Composite as Catalysts for Enzymatic Oxygen Reduction
Authors: Zhou Yan , Umasankar Yogeswaran , Ramasamy Ramaraja P
Published: October 2014

The immobilization of laccase on metal oxide nanoparticles was achieved using a silane coupling agent and a homobifuntional cross-linking agent. The metal oxide nanoparticles studied were TiO2, ZnO and SnO2. The coupling agent was silane and the crosslinking agents was 1,5-Difluoro-2,4-dinitrobenzene (DFDNB). The resulting laccase-metal oxide bio-nanocomposites were deposited onto screen printed carbon electrode and tested as electrocatalysts for oxygen reduction in an electrochemical cell using 0.2 M pH 4.5 sodium acetate buffer as the electrolyte. The bio-nanocomposite modified electrode showed an open circuit potential as high as 0.61 V vs Ag/AgCl. Cyclic voltammograms showed a clear difference between unmodified and laccase modified metal oxide nanoparticles in the oxygen reduction region with an onset potential of ~ 0.57 V. In comparison, the laccase physisorbed onto the metal oxide nanoparticles without the molecular crosslinkers showed no obvious electrocatalytic activity. The work adds significant value to the bio-electrochemistry literature, as a new class of support material with photocatalytic properties have been found to serve as excellent enzyme immobilization support that has potential applications in biosensors and biological fuel cells.
Electroless Displacement Deposition of Nanocrystalline Al on Mg Surface from AlCl3-Emic Room Temperature Ionic Liquid
Authors: Xu Bajin , Zhang Min , Xue Dongpeng , Qu Rui , Ling Guoping
Published: October 2014

In this paper, electroless displacement deposition of Al on Mg surface in AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3–EMIC) ionic liquid was reported. The electrolytic etching pretreatment of Mg substrate was employed to remove the oxide layers on the surface. The process of displacement deposition was studied by open-circuit potential (OCP) measurement. The electroless deposited Al on Mg was characterized by grazing incidence X-ray diffraction (GIXRD) and scanning electron microscope (SEM). The results showed that for the Mg substrate with oxide layer on the surface, microcrystalline Al crystals of 10-20 μm were obtained in the way of immersing the Mg directly in the ionic liquid. But for the Mg substrate with oxide layer removed, the deposited Al crystals by placing the Mg in the ionic liquid were nanocrystalline, while Al particles of 200-300 nm were deposited by placing the substrate in the glove-box with residual ionic liquid on the surface.
Development in Phosphor Glass Ceramic Composites
Authors: Chung Yuan-Run , Chang Chih-Kun , Liao Jin-Hong , Wu Fan-Bean
Published: October 2014

The Bi doped borosilicate glass systems with low characteristic temperature and high refractive index were fabricated. Through microstructure control by Bi and Zn doping, a low softening point around 476oC of the glass was achieved. The YAG phosphor was successfully embedded and dispersed into the softened glass substrate under heat treatment. The emission light of GCP sample can be controlled from blue to white and yellow under LED blue chip package through heat treatment.
The Impact of Pt-Nanocluster Deposition and Nafion® Content on the Oxygen Electroreduction Kinetics on Molybdenum Carbide Derived Carbon Synthesized at 1000°C
Authors: Sepp Silver , Nerut Jaak , Vaarmets Kersti , Kanarbik Rait , Härk Eneli , Lust Enn
Published: October 2014

Molybdenum carbide derived carbon was used as a porous support for platinum catalyst. Platinum was deposited onto carbon support in the form of nanoparticles using NaBH4 reduction method in ethylene glycol, so that the loading of platinum was 8.5 wt% and the average size of platinum nanoparticles was 3 nm. The high resolution scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and the low temperature N2 sorption experiments were applied to characterize the structure of materials prepared. The kinetics of oxygen electroreduction was studied using cyclic voltammetry and rotating disc electrode methods in 0.5 M H2SO4 solution. The content of Nafion® was varied in the range from 5 to 30 wt%. As synthesized carbon exhibited high specific surface area and Nafion® binder disperses uniformly, the percentage of Nafion® has only slight influence on the electrochemical activity. Prepared catalyst materials demonstrated high activity towards oxygen electroreduction.
Lithium-Ion Cell Nail Penetration Safety Experiments under Adiabatic Conditions
Authors: Reichert Mathias , Haetge Jan , Berghus Debbie , Wendt Christian , Meier Vladislav , Rodehorst Uta , Passerini Stefano , Schappacher Falko , Winter Martin
Published: October 2014

Nail penetration tests under adiabatic conditions are proposed as a new safety test method to simulate a short circuit caused by intrusion in the worst case scenario, i.e., adiabatic conditions. The behaviors of commercially available 18650 type lithium-ion cells with two different cell chemistries, LiNi0.33Co0.33Mn0.33O2 - LiCoO2 blend (NCM-LCO blend) vs. graphite and LiFePO4 (LFP) vs. graphite, were investigated at different states of charge (SoC). The results show a small standard deviation for the temperature and pressure measurements from five identical experiments. The detailed examination of the nail penetration experiments reveals differences in the safety properties of the cathode materials (LFP vs. NCM-LCO), separator types (PP PE PP trilayer vs. PE single layer) and electrode designs (high power vs. high energy). For both cell types, the observed cooling effect at high energy contents could be linked to an increased gas production due to the loss of electrolyte.
Compact Analytical Modeling of Li-Air Batteries with Organic Electrolyte at Low Discharge Currents
Authors: Bevara Vamsci V , Andrei Petru
Published: October 2014

A compact model is developed for the discharge curves and specific capacity of Li-air batteries with organic electrolyte as a function of the galvanostatic discharge current and specific capacity. The Li2O2 deposit layer formed in the cathode is modeled using two approaches: as a resistive layer and as a quantum barrier. In each case the voltage drop across the deposit layer is computed analytically. The model considers Butler-Volmer reaction kinetics at anode and cathode to obtain expressions for the anode and cathode overvoltages as functions of time. The solution for the porosity change equation, the rate equation for deposition of the discharge product, and the solutions for the overvoltages at anode and cathode are used to obtain a closed-form expression for the discharge voltage as a function of the specific capacity and other parameters of the battery.
Advanced Diagnostics Applied to a Self-Breathing Fuel Cell
Authors: Obeisun Oluwamayowa Ayokunle , Meyer Quentin P.-G. , Robinson James , Gibbs Christopher , Kucernak Anthony R. J. , Shearing Paul R , Brett Dan J. L.
Published: October 2014

In a self-breathing fuel cell, oxygen is taken directly from ambient air which provides the benefit of reduced system complexity and system operation. This study explores the use of, printed circuit boards (PCBs) as flow field plates to design a self-breathing fuel cell which helps reduce overall volume and cost of the system. It investigates the effect opening ratios have on fuel cell performance using polarization curves and electrochemical impedance spectroscopy. The result obtained indicates that greater opening ratios improve the mass transport properties of the fuel cell but increased Ohmic resistance as a result of the increased openings and reduced area of lands/ ribs respectively. A maximum power density of 188 mW cm-2 was achieved.
Polybenzimidazole Membranes for Hydrogen Production in the Hybrid Sulfur Electrolyzer
Authors: Garrick Taylor Reed , Gulledge Alexander , Staser John A , Benicewicz Brian , Weidner John W.
Published: October 2014

The hybrid sulfur (HyS) thermochemical cycle has been studied as a means to produce large quantities of clean hydrogen at higher efficiencies than those possible from water electrolysis. Recent studies have shown that the HyS electrolyzer can be operated at with sulfuric acid-doped s-PBI membranes as opposed to traditional Nafion membranes. Our research has shown that s-PBI membranes provide the option of operating the cell at significantly elevated temperatures in order to reduce kinetic resistance.
Enhanced Catalytic Efficiency and CO Tolerance of Novel Pt Nanostructures Prepared by Pulsed Electrodeposition for Methanol Oxidation
Authors: Chuang Chen Kang , Yeh Tsung Kuang
Published: October 2014

Innovative platinum (Pt) nanostructures were developed in this study for enhancing the anode catalyst activities for proton exchange membrane fuel cell application. The platinum nanostructures were directly grown on carbon paper by a pulsed electrodeposition technique. The morphology of Pt nanostructures shown as dendritic structures. The sizes of the dendritic structures are 2-4 μm in length. A cyclic voltammetry analysis was carried out for characterizing the behavior of methanol oxidation on specimen bearing the Pt dendritic nanostructures. It was found that the peak current density of methanol oxidation was 277.5 mA/cm2. Due to its unique morphology, the Pt dendritic nanostructures could exhibit a good carbon monoxide tolerance and high efficiency without the joined Ruthenium catalyst. It is noteworthy that the if/ib value of the Pt dendritic nanostructures is higher than 1.4. The catalytic efficiency of prepared Pt dendritic nanostructures was much better than that of a commercial Pt-black catalyst.
Electrochemical Synthesis of Azanucleoside Derivatives Using a Lithium Perchlorate-Nitromethane System
Authors: Shoji Takao , Kim Shokaku , Kitano Yoshikazu , Chiba Kazuhiro
Published: October 2014

Azanucleosides are one of the sugar modified nucleoside analog, which contain a nitrogen atom instead of an oxygen atom of furanose ring in nucleoside. They have been known to have anti cancer and anti virus activity, thus the therapeutic application of them has been attracted much attention. However, the synthetic method of them has some issues to be addressed, and they have precluded the derivatization of azanucleoside based on the modification of nitrogen atom. In this report, we developed the easy and mild synthetic method of azanucleoside by using lithium perchlorate-nitromethan (LiClO4/MeNO2) electrolysis system. In this method, reactive intermediates were anodicaly generated from prolinol derivatives and accumulated in LiClO4/MeNO2 solution, and reacted with nucleophiles in the same pot. We synthesized azanucleoside derivatives having diversity on nucleobase, nitrogen substituent and pyrrolidinyl ring from prolinol derivatives directly.
The Study of Indirect Electroreductive Cyclization of Propargyl Derivatives Using [Ni(tmc)]Br2 as Catalyst in Ionic Liquids
Authors: Neto M. J. , Esperança J.M. S.S. , Esteves A. P. , Medeiros M. J. , Silva M. M.
Published: October 2014

Radical cyclization continues to be a central methodology for the preparation of natural products containing heterocyclic rings. The use of electrogenerated nickel(I) complexes as mediators for cathodic intramolecular cyclizations proved to be successful in the formation of carbocyclic products. In this work, the indirect electroreductive intramolecular cyclization of bromoalkoxylated derivatives 1 catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane)nickel(I), [Ni(tmc)]+, as the catalysts in the ionic liquids, N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide, [N1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium ethylsulfate, [C2mim][C2SO4] has been investigated by cyclic voltammetry and controlled-potential electrolysis. During controlled-potential electrolyses of solutions of Ni(II) complex in the presence of bromoalkoxylated derivatives 1, only five-membered-ring esters were obtained in moderate to good yields as the main products.
Generation of Active Sites by Potential-Driven Surface Processes: A Central Aspect of Electrocatalysis
Authors: Gottesfeld Shimshon
Published: October 2014

A wide variety of electrocatalytic processes taking place at either functionalized surfaces or “metal” surfaces, are , in fact, surface redox mediated . This means that the electrode potential defines the steady state population of active sites and suggests that the role of the potential in active site generation must be incorporated in the pre-exponential factor of the overall rate expression. In fact, the potential driven active site generation serves to “ignite” the faradaic process. This explains why the E0
redoc

system of M/Mox , or MOX+n/MOX+n+m surface couples , must be as close as possible to E0
cell process , to enable high conversion efficiency as well as higher rates at low overpotentials. The coinage metals are active ORR catalysts at high pH apparently because a different early step in the faradaic process results in highlighting of the benefit of active site generation at the lowest possible overpotential .
Manganese-Based Non-Precious Metal Catalyst for Oxygen Reduction in Acidic Media
Authors: Higgins Drew , Wu Gang , Chung Hoon T , Martinez Ulises , Ma Shuguo , Chen Zhongwei , Zelenay Piotr
Published: October 2014

Non-precious metal catalysts (NPMCs) based on manganese (Mn) are prepared by heat treating polyaniline (PANI), manganese acetate and Ketjenblack EC300J (KJ) carbon supports. Using a heat treatment temperature of 950oC, followed by an acid leaching and second heat treatment step, Mn-PANI-KJ catalysts are found to provide onset and half-wave potentials of ca. 0.90 and 0.77 V vs. RHE, respectively, in 0.5 M H2SO4 electrolyte. After 5,000 cycles of electrochemical durability testing, Mn-PANI-KJ demonstrates a half-wave potential loss of only ca. 20 mV, superior to the 80 mV loss for our previously developed iron (Fe)-PANI-KJ catalyst. Increased surface nitrogen concentrations and relative ratios of pyridinic to graphitic nitrogen species were observed at increased Mn-PANI-KJ preparation temperatures, along with the evolution of graphene-like and graphitic nanoshell structures.
Study of TiO2 Nanotube Formation Mechanisms by Simulation on Electric Domain
Authors: Zhao Ying , Hoivik Nils , Wang Kaiying
Published: October 2014

In this paper, we report the study on formation mechanisms of TiO2 nanotube by using COMSOL simulation of electric domain. The models are built according to existing field-assisted dissolution (FAD) model of the growth of highly self-organized TiO2 nanotubes structures. The simulation of morphological evolution over time provides a well forming process for smooth hemispheric bottom at the end of the nanotubes. Current density distribution through both initial nanocracks and as-formed nanopores suggests that the H+ ions during the FAD process are derived from the field-assisted oxidation process rather than from the electrolyte.
Electrical Properties of Lanthanum Silicate Apatite Electrolytes Prepared by an Innovative Chemical Route
Authors: Macedo Graziele Lopes , Macedo Daniel Araujo , Rajesh S , Martinelli Antonio Eduardo , Figueiredo Filipe M , Marques Fernando , Nascimento Rubens Maribondo
Published: October 2014

This work reports the synthesis of apatite-type lanthanum silicate powders with nominal composition La10Si6O27 by an innovative chemical route which combines co-precipitation and sol-gel approaches. The herein proposed synthetic procedure is advantageous in reducing energy consumption and processing time, key elements to decrease the total manufacturing cost. The as-prepared powder was calcined between 500 and 900 °C. Structure of the calcined powders, characterized by X-ray diffraction (XRD) and Rietveld refinement, indicated the formation of apatite crystalline lanthanum silicate with minor amount of L2O3 at 900 °C. The apatite powder was further analyzed by scanning electron microscopy (SEM). The effect of sintering temperature, ranging from 1400 to 1450 °C, on the electrical properties was investigated by impedance spectroscopy. Electrical measurements were recorded in the 400 – 800 °C temperature range. The lanthanum silicate electrolyte sintered at 1450 °C exhibited total electrical conductivity (σ700 ºC = 2.12 x 10-3 S.cm-1) comparable with samples from literature prepared by sol-gel and freeze drying methods and sintered at 1500 °C. The results in the present study demonstrate that the co-precipitation method combined with a sol-gel approach is a promising alternative route to synthesize lanthanum silicate powders.
Cycling of a Quinone-Bromide Flow Battery for Large-Scale Electrochemical Energy Storage
Authors: Huskinson Brian , Marshak Michael P. , Gerhardt Michael R. , Aziz Michael J.
Published: October 2014

We have demonstrated the performance of an aqueous redox flow battery composed of a negative electrode consisting of a redox couple between anthraquinone di-sulfonate and its corresponding hydroquinone, and a positive electrode consisting of a redox couple between hydrobromic acid and bromine. The peak power density is approximately 0.6 W/cm2. After 750 deep cycles, the average discharge capacity retention is 99.84% per cycle and the average current efficiency is 98.35%.
Hydrothermal Synthesis of Nickel Disulfide and Its Application in Thermal Battery
Authors: Yang Zhaotang , Liu Xiaojiang , Cui Yixiu
Published: October 2014

Cubic phase nickel disulfide (NiS2) materials have been synthesized via hydrothermal method with the reactants of NiSO4, S and FeSO4. The size of the synthetic NiS2 particles is about 2.8 μm in average according to the laser particle size analysis. The discharging experiments reveal that the NiS2 has smaller polarization than that of the natural FeS2 due to its small electrical resistivity and large surface area contacting with electrolytes. When discharging at the condition of large current density or pulse current density, the NiS2 thermal battery shows better electrochemical performance than that of the FeS2 thermal battery.
Ablating L-FABP in SCP-2/SCP-x null mice impairs bile acid metabolism and biliary HDL-cholesterol secretion
Authors: Martin Gregory G. , Atshaves Barbara P. , Landrock Kerstin K. , Landrock Danilo , Storey Stephen M. , Howles Philip N. , Kier Ann B. , Schroeder Friedhelm
Published: October 2014

On the basis of their abilities to bind bile acids and/or cholesterol, the physiological role(s) of liver fatty acid-binding protein (L-FABP) and sterol carrier protein (SCP) 2/SCP-x (SCP-2/SCP-x) gene products in biliary bile acid and cholesterol formation was examined in gene-ablated male mice. L-FABP (LKO) or L-FABP/SCP-2/SCP-x [triple-knockout (TKO)] ablation markedly decreased hepatic bile acid concentration, while SCP-2/SCP-x [double-knockout (DKO)] ablation alone had no effect. In contrast, LKO increased biliary bile acid, while DKO and TKO had no effect on biliary bile acid levels. LKO and DKO also altered biliary bile acid composition to increase bile acid hydrophobicity. Furthermore, LKO and TKO decreased hepatic uptake and biliary secretion of high-density lipoprotein (HDL)-derived 22-( N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3β-ol (NBD-cholesterol), while DKO alone had no effect. Finally, LKO and, to a lesser extent, DKO decreased most indexes contributing to cholesterol solubility in biliary bile. These results suggest different, but complementary, roles for L-FABP and SCP-2/SCP-x in biliary bile acid and cholesterol formation. L-FABP appears to function more in hepatic retention of bile acids as well as hepatic uptake and biliary secretion of HDL-cholesterol. Conversely, SCP-2/SCP-x may function more in formation and biliary secretion of bile acid, with less impact on hepatic uptake or biliary secretion of HDL-cholesterol.
The use of doubly labeled milk protein to measure postprandial muscle protein synthesis rates in vivo in humans
Authors: Burd Nicholas A. , Cermak Naomi M. , Kouw Imre W. K. , Gorissen Stefan H. , Gijsen Annemie P. , van Loon Luc J. C.
Published: October 2014

We aimed to determine the impact of precursor pool dilution on the assessment of postprandial myofibrillar protein synthesis rates (MPS). A Holstein dairy cow was infused with large amounts of L-[1-13C]phenylalanine and L-[1-13C]leucine, and the milk was collected and fractionated. The enrichment levels in the casein were 38.7 and 9.3 mole percent excess, respectively. In a subsequent human experiment, 11 older men (age: 71 ± 1 y, body mass index: 26 ± 0.1 kg·m−2) received a primed constant infusion of L-[ring-2H5]phenylalanine and L-[1-13C]leucine. Blood and muscle samples were collected before and after the ingestion of 20-g doubly labeled casein to assess postprandial MPS based on the 1) constant tracer infusion of L-[ ring-2H5]phenylalanine, 2) ingestion of intrinsically L-[1-13C]phenylalanine-labeled casein, and 3) constant infusion of L-[1-13C]leucine in combination with the ingestion of intrinsically L-[1-13C]leucine-labeled casein. Postprandial MPS was increased ( P < 0.05) after protein ingestion (∼70% above postabsorptive values) based on the L-[1-13C]leucine tracer. There was no significant stimulation of postprandial MPS (∼27% above postabsorptive values) when the calculated fractional synthesis rate was based on the L-[ring-2H5]phenylalanine ( P = 0.2). Comparisons of postprandial MPS based on the primed continuous infusion of L-[1-13C]leucine or the ingestion of intrinsically L-[1-13C]phenylalanine-labeled casein protein demonstrated differences compared with the primed continuous infusion of L-[ ring-2H5]phenylalanine ( P > 0.05). Our findings confirm that the postprandial MPS assessed using the primed continuous tracer infusion approach may differ if tracer steady-state conditions in the precursor pools are perturbed. The use of intrinsically doubly labeled protein provides a method to study the metabolic fate of the ingested protein and the subsequent postprandial MPS response.
Effect of high-fat and high-carbohydrate diets on pulmonary O2uptake kinetics during the transition to moderate-intensity exercise
Authors: Raper J. A. , Love L. K. , Paterson D. H. , Peters S. J. , Heigenhauser G. J. F. , Kowalchuk J. M.
Published: October 2014

Mitochondrial pyruvate dehydrogenase (PDH) regulates the delivery of carbohydrate-derived substrate to the mitochondrial tricarboxylic acid cycle and electron transport chain. PDH activity at rest and its activation during exercise is attenuated following high-fat (HFAT) compared with high-carbohydrate (HCHO) diets. Given the reliance on carbohydrate-derived substrate early in transitions to exercise, this study examined the effects of HFAT and HCHO on phase II pulmonary O2uptake (V̇o2p) kinetics during transitions into the moderate-intensity (MOD) exercise domain. Eight active adult men underwent dietary manipulations consisting of 6 days of HFAT (73% fat, 22% protein, 5% carbohydrate) followed immediately by 6 days of HCHO (10% fat, 10% protein, 80% carbohydrate); each dietary phase was preceded by a glycogen depletion protocol. Participants performed three MOD transitions from a 20 W cycling baseline to work rate equivalent to 80% of estimated lactate threshold on days 5 and 6 of each diet. Steady-state V̇o2pwas greater ( P < 0.05), and respiratory exchange ratio and carbohydrate oxidation rates were lower ( P < 0.05) during HFAT. The phase II V̇o2ptime constant (τV̇o2p) [HFAT 40 ± 16, HCHO 32 ± 19 s (mean ± SD)] and V̇o2pgain (HFAT 10.3 ± 0.8, HCHO 9.4 ± 0.7 ml·min−1·W−1) were greater ( P < 0.05) in HFAT. The overall adjustment (effective time constant) of muscle deoxygenation (Δ[HHb]) was not different between diets (HFAT 24 ± 4 s, HCHO 23 ± 4 s), which coupled with a slower τV̇o2p, indicates a slowed microvascular blood flow response. These results suggest that the slower V̇o2pkinetics associated with HFAT are consistent with inhibition and slower activation of PDH, a lower rate of pyruvate production, and/or attenuated microvascular blood flow and O2delivery.