bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Self-Assembly of Aligned One Dimensional ZnO Nanorod Arrays on Electron Beam Lithographically Patterned Templates for Sensor Applications
Authors: Pradhan Aswini K , Samantaray C , Arslan M , Dondapati H , Birdsong T , Santiago K , Biswal D
Published: April 2014

We have demonstrated the attachment of aligned ZnO nanorod arrays on to the electron beam lithographically patterned oxide surface at lower beam energy. At higher beam energy (~ 20 KeV), the accumulated negative charges that already built on the surface in due course of irradiation restricts the growth of nanorod arrays. This causes a negative shielding potential close to the surface at micron level, and completely unfavorable for the attachment of the negative ZnO carriers. However, at comparatively lower beam energy (~ 5 KeV or less), the secondary electrons are responsible for the pattern with the irradiation zone centered by the local positive field. This allows negatively charged ZnO nanorod arrays to grow at lower beam voltages, which initiate site selective attachments. This protocol of site selection is very useful for various sensor fabrications.
(Invited) Micromolding of NiFe and Ni Thick Films for 3D Integration of MEMS
Authors: Cortés Meritxell , Moulin Johan , Couty Magdalena , Peng Tao , Garel Olivier , Dinh Thi Hong Nhung , Zhu Yanan , Souadda Malika , Woytasik Marion , Lefeuvre Elie
Published: April 2014

Electrodeposition process was studied in order to obtain uniformly thick magnetic films which could be incorporated in magnetic microsensors and actuators. Ni and NiFe patterns of different dimensions were deposited by micromolding on a Cu/Ti seed layer. In the case of NiFe deposit, a linear deposition rate was calculated by measuring the deposit thickness using mechanical profilometry. The optimum pattern composition for the fabrication of magnetic microdevices was 80 at. % of Ni, that was found by comparing the magnetic properties of the deposits obtained from different conditions. The deposits structure was also characterized. All the parameters were studied as a function of the current density so that by controlling the electrodeposition conditions the characteristics of the deposits could be controlled. NiFe films were integrated in multilayered magneto-impedance sensors. They present good adherence even after performing annealing at both 300°C and 500°C and sensor sensitivity reaches 10%/Oe.
Investigating Surfaces by Complimentary Chemical Spectroscopies
Authors: Halada Gary P.
Published: April 2014

Use of complimentary analytical techniques has been the standard for surface and interface analysis for some time. The availability of techniques that can collect data from nanoscale films, as well as user facilities which provide access to synchrotron and other advanced spectroscopic techniques which are beyond the developmental capabilities of individual users, have over the past few decades enabled clarification of surface chemistry and mechanisms in corrosion, coatings, energy and environmental interactions. Combined with synthesis and modeling, characterization methods such as XPS, EXAFS, SIMS, vibrational spectroscopies and chemical mapping have allowed the design of incredibly useful experiments to explore surface and interfacial phenomena which govern the properties and performance of modern engineering materials. This review illustrates the value of such methods through key examples from coatings, corrosion, contamination and environmental remediation, and discusses how the methodology of combining complimentary chemical spectroscopies, advanced imaging and synthesis are informing the design of next-generation, high performance materials and structures. We also discuss the important contribution of complimentary spectroscopies for chemical analysis to materials engineering education.
Oxidation of Superalloys in Supercritical Water
Authors: Merwin Augustus , Rodriguez David , Chidambaram Dev
Published: April 2014

The formation and characterization of oxide films on nickel based superalloys as a result of exposure to supercritical water is of critical importance to thermal power industry. In this work, the oxide films formed on Inconel 625 and 718 after exposure to liquid water at 325°C and supercritical water at 425°C and 525°C are characterized using electron microscopy as well as Raman and X-ray photoelectron spectroscopies. It is found that the native CrO4
2- based films that provide these alloys their passive nature in liquid water are not present after exposure to supercritical water. When subjected to exposure to supercritical water, both alloys formed a duplex oxide film consisting of a base spinel, Ni(Fe,Cr)2O4, structure and a thin outer layer of NiO. The concentration of Fe in the spinel was found to increase at 525°C.
An XAS Study of the Surface of Low-Temperature Carburized Stainless Steel
Authors: Roeper Donald F. , O'Grady William E. , Pandya Kaumudi I. , Natishan Paul M.
Published: April 2014

X-ray absorption spectroscopy (XAS) is used to study the surface of low temperature carburized 316L stainless steel (SS) and untreated 316L SS to determine how the carburization process affects the surface structure of the treated samples. Low temperature carburization greatly improves the corrosion resistance and mechanical properties of stainless steel. The step heights in the XAS for the primary metal atoms remain the same for both carburized and untreated samples, indicating no significant change in the relative concentrations of each of the different metals in the surface. The location of the carbon has been determined to be in the octahedral interstices of the FCC lattice.
Corrosion of Carbon Steel in Physically-Constrained Locations in HLNW Isolation Containers
Authors: Engelhardt George , Kursten Bruno , Macdonald Digby D
Published: April 2014

A bounding model has been developed to calculate the impact of the porous, outer layer of the passive film on the corrosion rate of the carbon steel overpack and on the structural integrity of the concrete in the annulus of a supercontainer proposed for storage of high level nuclear waste. This model allows us to estimate the corrosion potential, rates of general corrosion of the overpack, hydrogen pressure, water saturation, and the porosity of the rust as corrosion proceeds along the corrosion evolutionary path. It is shown that, at lower values of water saturation S < 0.2-0.3, complete exhaustion of water within the annulus in predicted, completely protecting the overpack from further general corrosion. At higher values of water saturation the overpack is also predicted to be protected by the compression of the outer layer against the concrete buffer and hence by the reduction in porosity of the rust to form an impervious barrier.
pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries
Authors: Xia Da-Hai , Zhu Ren-Kang , Shen Chen , Behnamian Yashar , Lu Yu-Cheng , Luo Jing-Li , Klimas Stan
Published: April 2014

The effects of pH on sulfur-induced passivity degradation of Alloy 800 in simulated crevice chemistries were evaluated using electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis method. Experimental results reveal that the detrimental effect of impurities containing sulfur at the reduced or intermediate oxidation level (Sx) on the passivity of Alloy 800 depends significantly on the solution pH. In neutral crevice (NC) chemistry containing chloride ions, the Sx obstructs the healing process during repassivation, retards the dehydration reaction and also incorporates H, –OH and S into the passive film. However, the detrimental effect of Sx is insignificant in a basic crevice (BC) solution due to a change in surface adsorption and surface charge. Impurities containing sulfur at the reduced or intermediate oxidation level would cause Alloy 800 to lose its passivity and become active in an acidic crevice (AC) chemistry. Experimental evidence also indicates that the solution pH alters the semiconductor type of the surface film —from n-type in NC solution to p-type in BC solution.
Modeling the Chloride Ion Attack of Aluminum Oxide by XANES Analysis
Authors: Roeper Donald F. , O'Grady William E. , Natishan Paul M.
Published: April 2014

This paper is a summary of previously published work. We have generated molecular simulations of Cl¯ located at different sites in several aluminum oxide models and carried out local l-projected density of states (LDOS) calculations to obtain the theoretical spectra. These are compared to our earlier experimental X-ray absorption near edge structure (XANES) data in order to study the interactions of chloride ions with the passive oxide film on aluminum as a function of electrochemical potential at the Cl K-edge. We show that the chloride first attacks the hydroxyl components of the aluminum oxide, penetrates the oxide film and finally attacks the metal surface. This has led to a number of new insights in the mechanism of the breakdown of the passive oxide film in chloride solutions.
Thin Surface Films over Copper–Nickel Alloys: Corrosion Behavior in Neutral and Acidic Medium in Presence of Chloride Ions
Authors: Al-Kharafi Faizah M , Abdel Nazeer Ahmed , Abdullah Ragab M , Galal Ahmed
Published: April 2014

Oxide films were grown over 90Cu-10Ni alloy using electrochemical polarization. The structure of the films was determined using a variety of surface techniques. Polarization curves were recorded for the alloy in different electrolytes of chloride, sulfate and the corresponding mixtures. It was ascertained that a protective layer consisting mainly of a thin, strongly adherent inner barrier Cu2O-layer that is followed by a porous and thick outer Cu(II) hydroxide/oxide-layer is formed. Nickel affects the barrier properties of the surface film through a segregation of Ni from the alloy into the Cu2O layer. The composition of the film formed over 90Cu-10Ni alloy was determined at different polarization times using FE-SEM/EDAX, XPS, ICP-ES, and electrochemical measurements. The ratio of Cu:Ni is maintained in the film composition after few seconds from the inset of polarization in chloride containing electrolytes. Ni-content in the film decreases and then increases after 30 and 60 minutes of the inset of polarization, respectively. In sodium sulfate and sulfuric acid solutions, the Cu:Ni ratio in the film is respected throughout the polarization times.
Evaluation of Corrosion Resistance of Multilayered Sn/Ag3Sn Electroplating on Cu Alloys for Electric Connectors
Authors: Chu-Kure Song-Zhu , Yashiro Hitoshi
Published: April 2014

The anti-corrosion performances of multilayered Sn/Ag3Sn films with Ag thickness of 50 nm on Cu alloy materials were evaluated through a sulfidizing test in (NH4)2Sx solutions and an aging test at 473 K up to 2000 h, comparing with a commercial pure Ag film and a conventional reflowed Sn film on Cu alloy materials. The multilayered Sn/Ag3Sn films succeeded in the accelerated sulfidizing test, with unchanged appearance and stable electrical contact resistance, even after immersion in a 0.2 ml/L (NH4)2Sx solution for 120 h. Moreover, the multilayered Sn/Ag3Sn films exhibited low and stable electrical contact resistances equivalent to as-plated samples even after heating at 473 K for 2000 h. The excellent corrosion resistance of the multilayered Sn/Ag3Sn films can be mainly ascribed to the chemical stable Ag3Sn covered with a thin Sn oxide film and the inward Ag diffusion that suppressing outward Cu diffusion during aging.
Stability of Photoactive Oxide Semiconductors
Authors: Gakhar Ruchi , Chidambaram Dev
Published: April 2014

ZnxCd1-xSe quantum dot-sensitized TiO2 nanotube (TiO2 NT) array photoelectrodes were synthesized employing successive ionic layer adsorption and reaction (SILAR) technique. The influence of the number of deposition cycles and post-deposition annealing temperature on photoelectrochemical properties and stability behavior of photoanodes was investigated. The photoanodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. Photoelectrochemical measurements indicated that TiO2 NTs coupled with ZnCdSe quantum dots synthesized with 7 SILAR cycles, annealed at 400oC for 1hr under N2 atmosphere exhibited excellent photoelectrochemical properties. The high and stable photocurrent produced demonstrates the potential of ZnxCd1-xSe/TiO2 heterostructure as an efficient photoanode.
Light Thermal Damage in Polymer Composite Systems: Analysis of Bulk and Surface Properties through Vibrational and X-Ray Spectroscopy
Authors: Clayton Clive R. , Young Christopher N. , Granata Richard D. , Scott William R. , Connelly Guy M.
Published: April 2014

Polymer composite materials have shown significant advances in the replacement of metals as structural materials in military applications. While these materials are lighter and stronger, they are also substantially more susceptible to degradation from conditions where metals are unperturbed. In addition to ultraviolet radiation, exposure to service temperatures above Tg but below the point of burning can lead to premature material failure. In this work, we explore the effects of this “light” thermal damage on the bulk properties of a carbon fiber / vinyl ester composite, and examine the changes in surface oxidation and other modes of decomposition, in the hopes of better understanding the bulk changes. Laser-induced fluorescence has been used to detect thermal exposure, and has been related to changes in mechanical properties of the composite. The surfaces of both the composite and neat resin have been studied with Raman, FTIR, and X-ray spectroscopic methods in order to detect surface and near-surface changes in chemistry. Common trends in changes of properties with increasing exposure will be discussed.
All-Solid Semiconductor-Sensitized Solar Cells Made by Electrodeposition
Authors: Lévy-Clément Claude , Elias Jamil , Ivanova Valentina
Published: April 2014

It would be very attractive to fabricate (Extremely Thin Absorber) ETA-solar cells using one single technique of deposition such as the electrochemical one, as this would facilitate the assembly of the solar cells and reduce cost of production. In the ZnO-NWs/CdSe/CuSCN solar cells, the ZnO nanowires (NWs) and the absorber, CdSe, were already made by electrochemical deposition. In this paper, the electrodeposition of the 2D ZnO buffer layer and p-type CuSCN was investigated as well as the possibility to use them in the solar cell assembly. Formation of vertically free standing CuSCN nanowires opened the route to built ETA-solar cells with an inverted configuration.
Series Circuit of Organic Thin-Film Solar Cells for Electrochemical Conversion of Water into Hydrogen
Authors: Aoki Atsushi , Hori Tomoaki , Naruse Mitsuru , Abe Takayuki
Published: April 2014

Series circuit of organic thin-film solar cells (OSCs), which are bulk hetero-junction (BHJ) solar cell composed of poly(3-hexylthiophene) (P3HT) as a donor and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an acceptor, has been investigated for electrolyzing water to hydrogen and oxygen gases. The cell performance parameters of OSC, such as the annealing time, P3HT/PCBM film thickness and the conductivity of PEDOT/PSS film were optimized. The series circuit of 6 unit OSCs shows the open circuit voltage (Voc) of 3.48 V, which is enough for electrolyzing water. By combination of water electrolysis cell using carbon supported Pt nanoparticles cathode and Ni anode, and the series circuit solar cells, the electrolyzing current and voltage are obtained to be 2.7 mA/cm2 and 2.2V, respectively under the simulated solar light irradiation. Hydrogen is generated to 0.5 mL after an hour irradiation.
Copper Coated LiCoO2 Particles for Water Friendly Electrodes in Li-Ion Batteries
Authors: Spreafico Marco , Cojocaru Paula , Triulzi Francesco , Apostolo Marco , Magagnin Luca
Published: April 2014

Metal oxide-based coatings have been applied on LiCoO2 particles in order to allow the use of water as solvent in the manufacturing process of the cathodes for Li-ion batteries. The coating has been obtained by oxidation of a metallic layer deposited on the particles with electroless deposition. The treatment allowed the deposition of a copper (II) oxide layer on the particles as shown by XPS analysis. SEM investigation demonstrates that particles morphology is unchanged after the plating process. The treatment does not The electrodes manufactured with the coated powders of active material show an increased resistance to chemical decomposition in aqueous environment, as shown by electrochemical performances assessment, evaluated by means of galvanostatic cycling in coin cells. Capacity vs. cycles charts show that the stability of the cycling capacity is improved with respect to a cathode made of uncoated LiCoO2 particles and PVDF latex as binder.
Effects of Electrode Modification on the Air Electrode for Water Electrolysis
Authors: Chiu Yen-Wen , Chuang Shun-Hsing , Wu Chia-Hua , Lu Cian-Tong , Hsueh Kan-Lin , Hung Ju-Shei , Chang Wen-Sheng , Yang Chang-Chung
Published: April 2014

The oxygen evolution reaction (OER) is taking place on the air electrode during charging period of rechargeable metal air battery. Removal of gas bubbles from the electrode is one of the key issues for better performance. This study investigated the effects of surface modified on the polarization curve of air electrode. Stainless steel mesh coated with needle-like deposit had better performance than those without coating. Electrode with needle-like surface had substantially lower OER over-potential. This electrode was combined with electrode for oxygen reduction reaction for acharge-discharge cycling test. A stable charging potential over 428 cycles was achieved.
Effects of Gas Composition Just before Fuel Pulses on Power Generation Characteristics at Different Fuel Supply Frequency in Pulse Jet-Rechargeable Direct Carbon Fuel Cells
Authors: Sugiyama Shiori , Yabuki Akinori , Tanaka Hiroki , Chen Ying , Ihara Manabu
Published: April 2014

Pulse Jet - Rechargeable Direct Carbon Fuel Cells (PJ-RDCFCs), in which small amounts of liquid hydrocarbon are supplied by pulse jet, were found to show different power generation characteristics depending on the time interval between fuel pulses (T
int). For the T
int range studied here (1 to 210 sec), both the maximum terminal voltage during a single cycle and the increase rate just after a fuel pulse can be controlled by T
int, and this T
int determines the fuel utilization and partial pressure of H2O and CO2. Thus, the gas composition just before a fuel pulse determines the degree of reforming reaction and chemical species contributing to the electrochemical reaction, which affects the power generation characteristics. Power generation at extremely short T
int (1 sec) revealed that during pulse jetting, the terminal voltage was stable. Its average power density was 445 mW/cm2, which is high for electrolyte-supported SOFCs that use liquid hydrocarbon.
Improved Effect of Anode-Additive PrBaInOx and Gd-doped BaCeO3 on the Electrochemical Performance of Solid Oxide Fuel Cells
Authors: Noda Yohei , Li Xinyu , Shimada Hiroyuki , Ihara Manabu
Published: April 2014

PrBaInOx (PBI) and materials with related structures of perovskite were added to the anode of Solid Oxide Fuel Cells (SOFCs). The electrochemical performance of SOFCs improved by addition of PBI particles to the Ni/GDC anode in dry methane fuel. The effect of added PBI and materials with related structures of perovskite on the electrode characteristics was then investigated to determine the appropriate SOFC anode additive. Electrochemical measurements of Ni/GDC anodes with added PBI, PrInO3, BaCeO3 and Gd-doped BaCeO3 (BCG) suggest that BCG is the most effective anode additive for dry methane fuel. With wet H2 (1% H2O) fuel, the addition of BCG improved the electrochemical performance only of the Ni-free GDC anode, possibly due to the difference in hydrogen dissociative adsorption performance with and without Ni.
Electrochemical Deposition of Terbium from Molten Salts
Authors: Rayaprolu Sanjeev , Chidambaram Dev
Published: April 2014

Terbium, a rare earth metal, is used in a range of applications from phosphors to defense systems. While the application for the use of terbium is increasing, its supplies are shrinking. This study explores the ability to recycle terbium via a molten salt electrochemical process. TbCl3 was chosen as the precursor for the electrochemical deposition of terbium from a molten LiCl-KCl medium. Using a graphite anode and a tungsten cathode, Tb was successfully deposited. However, the current efficiency was found to vary depending on the process variables. The temperatures investigated ranged from 400-8000C. Process variables studied include temperature, concentration, deposition potential, current density, and period of deposition. Spectroscopic techniques including SEM, EDS, and XPS, were used to confirm the electrodeposition of terbium on cathode; gravimetric measurements were used for quantitative analysis. Under optimal conditions, terbium was electrodeposited at a current efficiency of 27.2%.
Photochemical Route for the Preparation of Complex Amorphous Water Oxidation Catalyst
Authors: Smith Rodney D. L. , Trudel Simon , Berlinguette Curtis P.
Published: April 2014

A photochemically initiated decomposition reaction was used to synthesize a series of amorphous mixed-metal oxide films. The series, consisting of mixed-metal oxides included binary and ternary mixtures containing Fe, Co and/or Ni, enabled a systematic evaluation of amorphous metal oxides with complex compositions. X-ray diffraction results indicate that the as-deposited films are amorphous and can be converted to their crystalline form by heating. Infrared spectroscopy of the films indicates the photochemically driven process drives complete loss of the organic constituents from the film. X-ray photoelectron spectroscopy confirmed the loss of the organic ligand and enabled estimation of metal oxidation states. Electrochemical characterization revealed significant variation in catalytic performance toward the oxygen evolving reaction (OER) upon variation of metal oxide composition. Analysis of the Tafel behavior was used to distinguish amorphous mixed-metal oxide films to enable several film compositions to exhibit excellent electrocatalytic OER performance.
Continuous Fabrication of SOFC Assembly by ESD Technique – Dense Thin Film YSZ Electrolyte
Authors: He Quanzhi , Selman J. Robert , Nash Philip
Published: April 2014

Electrostatic spray deposition (ESD) was used to prepare a completely dense 0.7µm thin film of YSZ. The method of fabricating a SOFC cell assembly by a continuous ESD process with only one sintering step is discussed and illustrated.
The Hierarchical Functional Layers on High-Capacity Lithium-Excess Cathodes for Superior Lithium Ion Batteries
Authors: Zhao Jianqing , Aziz Saad , Wang Ying
Published: April 2014

Li-excess layered Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNCO) nanoparticles are facilely synthesized using a surfactant-assisted dispersion method. We synthesize a novel core-shell structure cathode consisting of Li-excess LMNCO as core and Li-stoichiometric LiCoO2 as shell, and its electrochemical property is optimized by tailoring weight content. In addition, the effect of ultrathin and conformal oxide coatings via atomic layer deposition (ALD) on improving electrochemical performance of LMNCO electrodes is simultaneously evaluated via tuning the composition. Finally, electrochemical performance of Li-excess cathode material can be maximized by surface modification with hierarch functional layers composed of 10 wt.% LiCoO2 shell (~10 nm thick) and six ZrO2 ALD layers (~1 nm thick), which delivers very high initial discharge capacities of 296.4 and 104.2 mAh/g at 0.1C and 10C, and can retain 184.0 mAh/g at 1C after 100 electrochemical cycles. Such remarkably improved cycleabilitiy and rate capability can be attributed to the synergic effect from hierarch functional coatings.
Optimizing the Composition of the Cu/Si Thin Film Anodes Produced via Magnetron Sputtering
Authors: Polat Deniz Billur , Eryilmaz Levent , Keleş Özgül
Published: April 2014

The reversible cyclability of Si based composite anodes is greatly improved by optimizing the atomic ratio of Cu/Si in the films fabricated via magnetron sputtering. The galvanostatic test results show that the thin film anode made of 20%at. Cu delivers 1950 mAhg-1 as the initial discharge capacity with 80% Coulombic efficiency. Then, after the 50th cycles 80% of the initial discharge capacity is retained, with 99.5 % Coulombic efficiency. This remarkable performance can be explained by small crystalline sizes, amorphous structures of the thin film and its enhanced physical and mechanical properties due to the 20 %at. Cu content. High specific capacities achieved in this study prove that magnetron sputtering deposition might be a good alternative production technique to fabricate high performance anode materials. Furthermore, this one step, environmentally friendly process enables one to control the film composition, structure as well as adhesion which minimizes delamination and pulverization.
Improving the Electrochemical Performance of the Tin Based Anodes formed via Oblique Angle Deposition Method
Authors: Polat Deniz Billur , Sezgin Nagihan , Keleş Özgül
Published: April 2014

An oblique angle electron beam co-deposition technique was used to fabricate nanostructured Sn based thin films: Sn, Cu-Sn and Cu-Sn-C. The morphological and structural properties of the films were observed via scanning electron microscopy (SEM) and thin film X-ray diffraction methods (XRD). The cyclic voltammetry (CV) and the galvanostatic test results demonstrated that the addition of Cu with or without C affected the electrochemical performance of the thin film positively since Cu and C improved both the mechanical and the electrical properties of the nanostructured Sn thin film electrode. The high cycleability and the capacity retention were achieved when the nanostructured Cu-Sn-C thin film was used as an anode material since C increased the mechanical tolerance of the thin film to the volume expansion due to its grain refiner effect, and Cu not only improved the electrical conductivity and the adhesion of the film to substrate but also the mechanical tolerance of the film with its ductile property.
Electrochemical Quartz Crystal Microbalance Measurements of Lithium-Aluminum Alloy in a Glyme-Lithium Salt Molten Complex
Authors: Serizawa Nobuyuki , Kobayashi Takeshi , Seki Shiro , Takei Katsuhito , Miyashiro Hajime , Katayama Yasushi , Watanabe Masayoshi , Miura Takashi
Published: April 2014

Lithium-aluminum alloying reaction was investigated in lithium bis(trifluoromethylsulfonyl)amide triglyme solvate ionic liquid as a model system for the negative electrode of lithium secondary batteries. The formation of β-phase LiAl was confirmed by X-ray diffraction. The potential of α+β coexisting region was approximately 0.35 V vs. Li/Li(I). The slow relaxation of open circuit voltage and scanning electron microscope images suggested the inhomogeneous alloying reaction along with the active sites. The mass changes with doping and undoping of Li were measured qualitatively by electrochemical quartz crystal microbalance technique.
Electrospun TiO2 Nanofiber Electrode with Optimized Diameters for Lithium Ion Battery
Authors: Cui Yanhua , Sun Ke , Sun Qian , Deng Yafeng , Lu Haiwei , Zhou Yongning , Fu Zheng-Wen
Published: April 2014

TiO2 nanofibers (NFs) with different diameters (range from 100 nm to 500 nm) have been prepared by electrospinning technique with the subsequent process of heat treatment. The obtained NFs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and their electrochemical performance has been investigated. The results showed a significant effect of the diameters of TiO2 NFs on their capacities and cycling stability. Polycrystalline TiO2 NFs with a diameter of 250 nm showed the best electrochemical performance.
The Use of Methyl Butyrate-Based Electrolytes with Additives to Enable the Operation of Li-Ion Cells with High Voltage Cathodes over a Wide Temperature Range
Authors: Krause Frederick C. , Hwang Constanza , Ratnakumar Bugga V. , Smart Marshall C. , McOwen Dennis W. , Henderson Wesley A.
Published: April 2014

In the present work, a number of wide operating temperature range electrolyte formulations that contain methyl butyrate (MB) and various additives have been investigated in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li1.2Ni0.15Co0.10Mn0.55O2 cathodes. In an attempt to improve the nature of the solid electrolyte interphase (SEI) and/or cathode electrolyte interface (CEI) of these systems, a number of electrolyte additives were investigated, including lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), 4,5-dicyano-2-(trifluoromethyl) imidazole (LiTDI), lithium tetrafluoroborate (LiBF4), and di-t-butylpyrocarbonate (DBPC). In summary, improved performance at low temperature power capability was observed for many of the methyl butyrate formulations, with the most dramatic improvement being observed for 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 0.10M LiDFOB. In addition, all of the methyl butyrate-based electrolytes studied resulted in improved rate capability compared to cells with the all carbonate-based baseline formulation at low temperature. It was also determined that at low temperatures that the cathode kinetics govern the rate capability, being the rate determining electrode.
Investigation of Electrolyte Additives with LiNi0.5Mn1.5O4/Graphite Cells at High Temperature
Authors: Delp Samuel A. , Allen Joshua L , Jow T. Richard
Published: April 2014

The spinel-structured LiNi0.5Mn1.5O4 (LNMO) has drawn much attention as a Li-ion battery cathode material with potential electric vehicle applications due to its high operating voltage (~4.7 V vs. Li/Li+) and relatively high energy density (~680 Wh kg-1). LNMO-based cells, however, tend to suffer from capacity fading due to transition metal dissolution that is exacerbated by increased temperatures. In this study, the electrolyte additives LiDFOB, HFiP, FEC and combinations of the three were investigated to determine which additives are able to properly passivate the LNMO surface to hinder Ni and Mn dissolution and thus enable high temperature cycling with a reduced fade rate. A combination of FEC and HFiP additives yielded the best high temperature performance with a Coulombic efficiency >97% and a decreased electrolyte decomposition above 4.8 V.
Bottlenecks to Fast Charging of Lithium-Ion-Insertion Cells for Electric Vehicles
Authors: Chandrasekaran Rajeswari
Published: April 2014

Customers of plug-in hybrid and all-electric vehicles may place a premium on the ability to quickly recharge the battery. However, several fundamental bottlenecks limit the charge acceptance of the battery pack at high rates. In this work, an isothermal, physics-based model is used for simulating the performance of a dual lithium-ion-insertion cell at various galvanostatic charge rates at room temperature. Simulation results show that the cell can be charged to ~ 55% SOC and 10% SOC at 3C and 10C rates respectively during the constant- current step before the cut-off potential is reached for the system under consideration. The various limitations are quantified in terms of their contributions to the cell overpotential. Simple expressions are provided to quickly evaluate limitations wherever feasible.
Thermal Conductivity, Heat Sources and Temperature Profiles of Li-Ion Batteries
Authors: Burheim Odne Stokke , Onsrud Morten Andreas , Pharoah Jon G. , Vullum-Bruer Fride , Vie Preben J. S.
Published: April 2014

In this paper we report the thermal conductivity of several commercial and non-commercial Li-ion secondary battery electrode materials with and without electrolytesolvents. We also measure the Tafel potential, the ohmic resistance, reaction entropyand external temperature of a commercial pouch cell secondary Li-ion battery. Finallywe combined all the experimentally obtained data in a thermal model and discuss thecorresponding internal temperature effects.The thermal conductivity of dry electrode material was found to range from 0.07to 0.41 WK−1m−1 while the electrode material soaked in electrolyte solvent rangedfrom 0.36 to 1.10 WK−1m−1. For all the different materials it was found that addingthe electrolyte solvent increased the thermal conductivity by at least a factor of three. For one of the anode materials it was found that heat treatment at 3000 K increasedthe thermal conductivity by a factor of almost five.Measuring the electric heat sources of an air cooled commercial pouch cell bat-tery at up to ± 2C and the thermal conductivity of the electrode components madeit possible to estimate internal temperature profiles. Combining the heat sources withtabulated convective heat transfer coefficients of air allowed us to calculate the ambi-ent temperature profiles. At 12C charging rate (corresponding to 5 minutes completecharging) the internal temperature differences was estimated to be in the range of 4-20K, depending on the electrode thermal conductivity. The external temperature dropin air flowing at the battery surface was estimated to nearly 40K. Evaluating thermal management of batteries in the light of our measurement led to the conclusion that ex-ternal cooling is more challenging than internal, though neither should be neglected.
Investigation of Particle Size and Coating Thickness for Pulse Performance of Automotive Lithium Ion Batteries
Authors: Sisk Brian C , Zhang Zhenli
Published: April 2014

Optimization of the performance of Micro-hybrid Electric Vehicles (MHEV) requires a close match between the demands of the driving profile and the chemical and engineering characteristics of the material. Typical driving patterns present the opportunity for regenerative braking pulses that may be over 30 seconds in some cases. Our goal is to provide more opportunity for regenerative braking, particularly for high-speed, long deceleration pulses. In this work we have used electrochemical modeling of NMC 1:1:1 cells to investigate the effects of particle size, coating thickness, and system capability on the energy and power capability of lithium ion batteries. We demonstrate a novel metric for evaluating the regeneration capability of a cell – recovered energy per volume, Whrecov/L – against which these effects are optimized. Finally, we have modeled lithium concentration gradients in both the electrolyte and particle surface and have identified conditions under which regeneration capability is affected.
Diagnostics of Li-Ion Commercial Cells – Experimental Case Studies
Authors: Devie Arnaud , Dubarry Matthieu , Liaw Bor Yann
Published: April 2014

Here we present a case study in which a unique diagnostic tool is successfully applied to a battery diagnosis on the quantification of an overcharging event and the subsequent cycle aging behavior of a commercial LTO || NMC lithium-ion pouch cell. The degradation modes that resulted in capacity fade were identified and quantified without conventional postmortem analyses. An electrochemical inference technique and analysis was sufficient to yield accurate diagnosis quantitatively from simple current-voltage measurements. A modeling tool (called the ‘Alawa toolbox) was used to simulate various aging scenarios to provide useful validation to the analysis. Comparative diagnoses of two cells enduring the same cycle aging conditions were performed. One of the cell went through a typical cycle aging process at 25°C, while the other was imposed with an overcharging event at cycle 125. The state of the battery through the cycle aging, before and after the overcharging event and the subsequent cycle aging, were analyzed to identify the degradation modes in each cell and to quantify the respective contribution to the capacity fade.
Preparation and Characterization of the Sulfur-Carbon Nano-Composite Material for Li/S Battery
Authors: Yuan Yan , Lu Hai , Chen Baizhen
Published: April 2014

The sulfur-carbon (S-C) nano-composite material have been prepared by a simple chemical deposit method in an aqueous solution. The composite material was characterized by scanning electron microscopy, energy dispersive spectrometer, and differential scanning calorimetry-thermo gravimetric analysis. The electrochemical performance of the S-C cathode made of the composite material was studied by cyclic voltammetry, charge-discharge test, and electrochemical impedance spectroscopy. It is found that the sulfur particles in prepared S-C composite material have a sphere-like morphology with the size of around 20~30nm, and distribute uniformly around the carbon particles. The initial specific capacity of the S-C cathode in Li/S battery can reach to 1200mAhg-1, and retains at 700mAhg-1 after 50 cycles.
Sensitivity Analysis of Material Parameters on Performance of Lithium Ion Battery Using Electrochemical Modeling
Authors: Zhang Zhenli , Sisk Brian C
Published: April 2014

A variety of materials variables affect the performance of an automotive lithium ion battery. Some of the most important materials parameters include dynamic transport properties of electrolyte and solid material, including ionic conductivity, electronic conductivity, reaction rate, and lithium diffusivity. Understanding the relationship between changes to these materials parameters and performance of the battery is critical to battery design. In this work, we consider the impact of the sensitivity of these fundamental parameters within the context of two different systems: a power cell for hybrid electric vehicles (HEV) applications, and an energy cell for electric vehicle (EV) applications. These applications are simulated using high-pulse power capability (HPPC) and constant-current discharge tests. The range of variance and sensitivity of key electrochemical parameters are presented.
Construction of a General POD Basis for Faster Li-Ion Cell Simulations
Authors: Rubeša Jelena , Suhr Bettina
Published: April 2014

Fast and reliable simulation of an electrochemical Li-ion cellmodel is achieved using the proper orthogonal decomposition (POD) combined with the empirical interpolation method (EIM). A new POD basis construction method for efficient model reduction is introduced for the simulation of batteries at different C-Rates, pulses, constant voltage charge and rest steps. The proposed reduced order model agrees well with the finite element (FE) method solver and requires 14 times less computation time than the FE model.
Central adiponectin administration reveals new regulatory mechanisms of bone metabolism in mice
Authors: Wu Yuwei , Tu Qisheng , Valverde Paloma , Zhang Jin , Murray Dana , Dong Lily Q. , Cheng Jessica , Jiang Hua , Rios Maribel , Morgan Elise , Tang Zhihui , Chen Jake
Published: April 2014

Adiponectin (APN), the most abundant adipocyte-secreted adipokine, regulates energy homeostasis and exerts well-characterized insulin-sensitizing properties. The peripheral or central effects of APN regulating bone metabolism are beginning to be explored but are still not clearly understood. In the present study, we found that APN-knockout (APN-KO) mice fed a normal diet exhibited decreased trabecular structure and mineralization and increased bone marrow adiposity compared with wild-type (WT) mice. APN intracerebroventricular infusions decreased uncoupling protein 1 (UCP1) expression in brown adipose tissue, epinephrine and norepinephrine serum levels, and osteoclast numbers, whereas osteoblast osteogenic marker expression and trabecular bone mass increased in APN-KO and WT mice. In addition, centrally administered APN increased hypothalamic tryptophan hydroxylase 2 (TPH2), cocaine- and amphetamine-regulated transcript (CART), and 5-hydroxytryptamine (serotonin) receptor 2C (Htr2C) expressions but decreased hypothalamic cannabinoid receptor-1 expression. Treatment of immortalized mouse neurons with APN demonstrated that APN-mediated effects on TPH2, CART, and Htr2C expression levels were abolished by downregulating adaptor protein containing pleckstrin homology domain, phosphotyrosine domain, and leucine zipper motif (APPL)-1 expression. Pharmacological increase in sympathetic activity stimulated adipogenic differentiation of bone marrow stromal cells (BMSC) and reversed APN-induced expression of the lysine-specific demethylases involved in regulating their commitment to the osteoblastic lineage. In conclusion, we found that APN regulates bone metabolism via central and peripheral mechanisms to decrease sympathetic tone, inhibit osteoclastic differentiation, and promote osteoblastic commitment of BMSC.
A Construction of Multisender Authentication Codes with Sequential Model from Symplectic Geometry over Finite Fields
Authors: Chen Shangdi , Yang Chunli
Published: April 2014

Multisender authentication codes allow a group of senders to construct an authenticated message for a receiver such that the receiver can verify authenticity of the received message. In this paper, we construct multisender authentication codes with sequential model from symplectic geometry over finite fields, and the parameters and the maximum probabilities of deceptions are also calculated.
Parameters Estimation and Stability Analysis of Nonlinear Fractional-Order Economic System Based on Empirical Data
Authors: He Lei , Wang Xiong
Published: April 2014

This paper is devoted to propose a novel method for studying the macroeconomic system with fractional derivative, which can depict the memory property of actual data of economic variables. First of all, we construct a constrained optimal problem to evaluate the coefficients of nonlinear fractional financial system based on empirical data and design the corresponding genetic algorithm. Then, based on the stability criteria of fractional dynamical systems, the methodology of stability analysis is proposed to investigate the stability of the estimated nonlinear fractional dynamic system. Finally, our method is applied to discuss the macroeconomic system of the US, Australia, and UK to demonstrate its effectiveness and applicability.
The Efficacy of Inositol and N-Acetyl Cysteine Administration (Ovaric HP) in Improving the Ovarian Function in Infertile Women with PCOS with or without Insulin Resistance
Authors: Sacchinelli Angela , Venturella Roberta , Lico Daniela , Di Cello Annalisa , Lucia Antonella , Rania Erika , Cirillo Roberto , Zullo Fulvio
Published: April 2014

Objective.Substances such as inositol and N-acetylcysteine (NAC) have been recently shown to be effective in treatment of PCOS patients. The aim of this prospective trial is to evaluate the efficacy of NAC + Inositol + folic acid on ovulation rate and menstrual regularity in PCOS patients with and without insulin resistance.Methods.Among the 91 PCOS patients treated with NAC + Inositol + folic, insulin resistance was present in 44 subjects (A) and absent in 47 (B). The primary endpoint was the ovulation rate/year, determined by menstrual diary, serum progesterone performed between 21° and 24° days, ultrasound findings of growth follicular or luteal cysts, and luteal ratio. HOMA-index assessment after 6 and 12 months of treatment was evaluated as secondary endpoint.Results.In both groups there was a significant increase in ovulation rate and no significant differences were found in the primary outcome between two groups. In group A, a significant reduction of HOMA-index was observed.Conclusions.The association NAC + Inositol + folic, regardless of insulin-resistance state, seems to improve ovarian function in PCOS patients. Therefore, inositol and NAC may have additional noninsulin-related mechanisms of action that allow achieving benefits also in those patients with negative HOMA-index.
Error Bounds and Finite Termination for Constrained Optimization Problems
Authors: Zhao Wenling , Song Daojin , Liu Bingzhuang
Published: April 2014

We present a global error bound for the projected gradient of nonconvex constrained optimization problems and a local error bound for the distance from a feasible solution to the optimal solution set of convex constrained optimization problems, by using the merit function involved in the sequential quadratic programming (SQP) method. For the solution sets (stationary points set and KKT points set) of nonconvex constrained optimization problems, we establish the definitions of generalized nondegeneration and generalized weak sharp minima. Based on the above, the necessary and sufficient conditions for a feasible solution of the nonconvex constrained optimization problems to terminate finitely at the two solutions are given, respectively. Accordingly, the results in this paper improve and popularize existing results known in the literature. Further, we utilize the global error bound for the projected gradient with the merit function being computed easily to describe these necessary and sufficient conditions.
Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor
Authors: Zhang Bo , Xiang Yong , Shrestha Santosh , Green Martin , Conibeer Gavin
Published: April 2014

Ge nanocrystals (Ge‐ncs) embedded in a SiO2 superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge‐O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen‐deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx) was then proposed to explain these findings and supplement the existing growth models for Ge‐ncs in SiO2 films. Further analysis of the bonding structure of Ge atoms suggested that Ge‐ncs are likely to have a core‐shell structure with an amorphous‐like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.
Remarks on Ultrametrics and Metric-Preserving Functions
Authors: Pongsriiam Prapanpong , Termwuttipong Imchit
Published: April 2014

Functions whose composition with every metric is a metric are said to be metric-preserving. In this paper, we investigate a variation of the concept of metric-preserving functions where metrics are replaced by ultrametrics.
Pathogenesis of Renal Failure in Multiple Myeloma: Any Role of Contrast Media?
Authors: Mussap Michele , Merlini Giampaolo
Published: April 2014

The spectrum of kidney disease-associated monoclonal immunoglobulin and plasma cell malignancies is remarkably broad and encompasses nearly all nephropathologic entities. Multiple myeloma with kidney impairment at presentation is a medical emergency since the recovery of kidney function is associated with survival benefits. In most cases, kidney impairment may be the first clinical manifestation of malignant plasma cell dyscrasias like multiple myeloma and light chain amyloidosis. Multiple myeloma per se cannot be considered a main risk factor for developing acute kidney injury following intravascular administration of iodinated contrast media. The risk is increased by comorbidities such as chronic kidney disease, diabetes, hypercalcemia, dehydration, and use of nephrotoxic drugs. Before the administration of contrast media, the current recommended laboratory tests for assessing kidney function are serum creatinine measurement and the estimation of glomerular filtration rate by using the CKD-EPI equation. The assessment of Bence Jones proteinuria is unnecessary for evaluating the risk of kidney failure in patients with multiple myeloma, since this test cannot be considered a surrogate biomarker of kidney function.