bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitridation of a Super-Ferritic Stainless Steel for PEMFC Bipolar Plate
Authors: Wang Heli , Turner John A. , Brady Mike P.
Published: September 2007

AL29-4C alloy nitrided in pure nitrogen resulted in a nitrogen-modified oxide surface, which is the same as AISI446 nitrided under identical conditions. When the alloy was nitrided 24h at 900{degree sign}C in N2-4H2, XRD and XPS analysis indicated that the surface layer consisted of a nitride outer layer (~0.20 µm) and an oxide inner layer (~0.82 µm). According to XPS, the nitride outer layer is composed of CrN and [Cr(N),Fe]2N1-x, with much more Cr2N than Fe2N. Mn is migrated and enriched in the oxide inner layer and combined with chromium oxide. AL29-4C alloy nitrided in N2-4H2 resulted in low ICR and excellent corrosion resistance in simulated PEMFC environments. Current was at ca. -3.0 µA/cm2 in the PEMFC anode environment, and at ca. 0.3 ~ 0.5 µA/cm2 in the cathode environment. This is considered to be rather stable. After being polarized in a PEMFC environment, the ICR increased slightly compared with the as-nitrided sample, but was still rather low.
Evaluation of Coatings and Surface Treatments for Stainless-Steel Fuel-Cell Flow-Field Plates.
Authors: Rivas Sandra V. , Manriquez Federico , Arriaga Luis G. , Orozco Germán
Published: September 2007

In this study several types of stainless steel, 304, 310, surface-modified 304 and 316, and 304 coated with TiN, were evaluated for corrosion resistance in simulated acidic fuel-cell media in order to determine their capacity for use as flow-field plates. The TiN coating was produced in an industrial sputtering operation. The modification of stainless steels 304 and 316 a hydrous oxide film was done by cycling of potential in 1M NaOH. Stainless steel 310 might perform satisfactorily as a bipolar plate. The behaviour of the nitrided material suggests the potential of this coating process.
Circular Transmission Line Model (CTLM) Analysis for Non-Linear VI Characteristics on Mg doped GaN
Authors: Patel Kinnari N. , Stokes E. , Pagan Jennifer , Burkhart Casey C. , Hodge Michael , Batoni Paolo
Published: September 2007

In this paper, we present a model that can be used to determine semiconductor material parameters for metal-semiconductor contacts with non-linear voltage-current (V-I) characteristics. The model uses the Circular Transmission Line Model (CTLM) approach to calculate sheet resistance (RSH) and resistivity (ρ) of Mg doped HVPE and MBE GaN epilayers giving values close to those achieved by Hall measurements.
Synthesis and Electrochemical Characterization of Platinum and Ruthenium Nanoparticles Encapsulated in PAMAM-G4OH Dendrimer for Oxygen Reduction in the Presence of Methanol.
Authors: Escalante García Ismailia L. , Ledesma García Janet , Rodríguez Francisco J. , Chapman Thomas W. , Godinez L. A.
Published: September 2007

In this work, we describe the preparation of composites of Pt, Ru and bimetallic Pt-Ru nanoparticles encapsulated in generation-four hydroxyl-terminated dendrimers (PAMAM-G4OH). The absorption of the metal ions and their chemical reduction were followed by UV-vis spectroscopy. Subsequently, the dendrimers encapsulating the Pt, Ru or Pt-Ru particles were immobilized on the oxidized surface of a glassy carbon electrode (GCE). Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements were used to determine the oxygen reduction reaction (ORR) kinetics on this surface in aqueous sulfuric acid media and in sulfuric acid solution containing methanol. Preliminary results show that the nanoelectrocatalyst exhibits good stability in these media and good electrocatalytic activity for the ORR in the presence of methanol.
Properties of ECD Gold Composite with Nanostructured Carbon-Based Materials
Authors: Cojocaru Paula , Santoro Marcello , Vicenzo Antonello , Cavallotti Pietro Luigi L.
Published: September 2007

Results of electrodeposition of gold matrix composite coatings with carbon-based materials, namely ultradispersed diamond UDD and carbon nanotube CNT, are reported. The effects of the bath load on some representative properties of the composite are specifically addressed. Pure gold and gold composite coatings were prepared from a gold sulfite electrolyte a pH 7.5 and bath load from 5 to 20 g l-1 (UDD bath) and from 0.1 to 5 g l-1 (CNT bath). The codeposition was characterized in terms of carbon content of the coating and by examination of the composite coating morphology. The particles incorporation rate and the concurrent impact on morphology were found to depend on both the bath load and the type of material used. The influence of codeposited material on microindentation hardness, wear behavior and thermal stability was further investigated. Some notable improvements of performance are observed in electrocodeposits compared to the pure matrix coatings. Critical factors affecting the codeposition behavior are highlighted in the light of the reported results.
Electrochemical Characterization of Submicrometer Structures
Authors: Suter Thomas , Schmutz Patrik , von Trzebiatowski Oliver
Published: September 2007

An electrochemical sensing technique based on nanocapillaries is presented. Corrosion tests can be performed on exposed areas with a diameter below 500 nm. The high current resolution of less than 1 fA (10-15A) allows the detection of early pit initiation processes and the characterization of smallest features in complex material structures. The technique was applied to track corrosion initiation processes at reinforcing particles on lead-free solder alloys and to evaluate the corrosion behavior of single phases on WC-Co hardmetals. The results showed that it would be beneficial to use Cu6Sn5 and not pure Cu- particles as reinforcing particles for lead free Sn Ag Cu solder alloys. Furthermore it was found that WC-Co hardmetals with an improved corrosion resistance should contain a tungsten carbide phase with a cobalt concentration of more than 3 atomic percent and cobalt phase with a tungsten concentration of more than 10 atomic percent.
Surface Processes Accompanying Corrosion-Induced Hydrogen Absorption into Aluminum
Authors: Adhikari Saikat , Lee Jinju , Hebert Kurt
Published: September 2007

The role of hydrogen-containing species in the alkaline dissolution of aluminum was studied by secondary ion mass spectrometry (SIMS). Large number densities of submicron particles nucleated and then disappeared during dissolution, at intervals of approximately 3 min. The particles were composed of aluminum hydride, with an aluminum hydroxide surface layer. When particles first appeared, the aluminate ion concentration near the surface was at the solubility of Al(OH)3, and the potential was close to the Nernst potential for oxidation of AlH3 to Al(OH)3. The observed formation of AlH3 indicates that the dissolving Al surface was poised near this equilibrium potential, i. e. that a hydride species serves as an intermediate in the dissolution process.
Corrosion Initiation and Anodic-Cathodic Alternation of Localized Corrosion of SiC-Reinforced Aluminum Composites in NaCl Solution
Authors: Ding Hongbo , Hihara Lloyd H.
Published: September 2007

Localized corrosion initiated on a 6092-T6 aluminum-based metal-matrix composite (MMC) reinforced with 20 vol.% SiC particles in an air-exposed 3.15 wt% NaCl solution. SEM indicated that corrosion initiated around SiC reinforcements. The polarization diagrams under illumination suggested that the SiC reinforcements were p-doped and that a semiconductor/electrolyte junction barrier existed. It was hypothesized that Al4C3 formed at the SiC-Al interface during the processing of the Al/SiC MMC. In the presence of water, the Al4C3 hydrolyzes and can induce crevices at the Al-SiC interfaces. Corrosion could thus initiate from these crevices. The scanning vibrating electrode technique revealed that the net currents over the localized corrosion region switched from anodic to cathodic, while the scanning ion-selective electrode technique revealed that the solution near the localized corrosion region switched from acidic to alkaline. The effects of solution pH on the local potential fluctuations of aluminum are believed to be related to this alternation.
Model for the Steady-State Growth of Porous Anodic Alumina Films
Authors: Houser Jerrod E. , Hebert Kurt
Published: September 2007

Simulations were developed for the distributions of electrical potential and incorporated anions in porous anodic alumina (PAA) films during steady-state growth. Predictions of a model for the potential distribution based on Laplace's equation were compared to those of the current continuity equation in conjunction with high-field conduction. It was found that Laplace's equation, which has been used previously in PAA models, resulted in strong violations of charge conservation, when the current density was evaluated using the high field conduction equation. Interface motion predicted by the current continuity equation was nearly uniform except near convex ridges on the metal-film interface. This model was extended to predict the distribution of anions in the film, since incorporated anions may provide suppression of conduction near the ridge. The spatial distribution of acid anions predicted by the model agreed with experimental observations.
Kinetic Stability Diagrams
Authors: Macdonald Digby D.
Published: September 2007

Our reactive metals-based civilization is possible only because of the formation of thin oxide (passive) films on surfaces that effectively separate the reactive metals from the corrosive environments. Previously, the conditions under which passivity occurred were defined in terms of equilibrium potential-pH relationships in the form of Pourbaix diagrams, which delineated regions of stability, passivity, and immunity. However, recent work has demonstrated that a passive film is never at equilibrium, but instead exists in the meta- stable state, if it exists at all. Thus, the limits of stability must be defined in terms of kinetic factors and not in terms of equilibrium principles. This has been done in the present study by phase space analysis of the rate law for film growth afforded by the Point Defect Model to yield Kinetic Stability Diagrams, which are proposed as kinetic alternatives to the equilibrium thermodynamic Pourbaix diagrams.
Corrosion Resistances of Iron-Based Amorphous Metals with Yttrium and Tungsten Additions in Hot Calcium Chloride Brine & Natural Seawater: Fe48Mo14Cr15Y2C15B6 and W-Containing Variants
Authors: Farmer Joseph C. , Haslam Jeffrey J. , Day Sumner D. , Lian Tiangan , Saw Cheng K. , Hailey Phillip D. , Choi Jor-Shan , Yang Nancy , Blue Craig A. , Peter William H. , Payer Joe H. , Branagan Daniel J.
Published: September 2007

Yttrium-containing SAM1651 (Fe48.0Cr15.0Mo14.0B6.0C15.0Y2.0), has a critical cooling rate (CCR) of approximately 80 Kelvin per second, while SAM2X5 (Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4) with no yttrium has a higher critical cooling rate of approximately 600 Kelvin per second. SAM1651's low CCR enables it to be rendered as a completely amorphous material in practical materials processes. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). The passive film stability of these Fe- based amorphous metal formulations have been found to be superior to that of conventional stainless steels, and comparable to that of Ni-based alloys, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates.
Insights into the Parting Limit for De-Alloying from Reconsideration of Atomistic Considerations
Authors: Artymowicz Dorota , Newman Roger , Erlebacher Jonah
Published: September 2007

The parting limit for de-alloying of a homogeneous binary alloy is shown to be plausibly related to a kind of high- density percolation threshold. Kinetic Monte Carlo simulations are used to establish the relevant thresholds with and without surface diffusion.
Studies of Electron Transfer at Aluminum Alloy Surfaces by Scanning Electrochemical Microscopy
Authors: Jensen Mark , Bjordahl Travis , Tallman Dennis E. , Bierwagen Gordon
Published: September 2007

Our corrosion group is investigating two classes of active coatings for corrosion control of Al alloys: conjugated polymers (CP) coatings and Mg metal rich (MgR) coatings. These coatings interact with the metal substrate by electron transfer processes, and by so doing, alter the corrosion behavior of the metal. Thus, it is important to understand the nature of electron transfer at the alloy surface. Furthermore, we have developed methods for the direct electrodeposition of CP coatings onto Al substrates using electron transfer mediation, and we are particularly interested in the influence of charge and structure of the mediator on the electron transfer process. Scanning electrochemical microscopy (SECM) is being used to study electron transfer at Al and Al alloy surfaces subjected to various surface treatments, employing mediators of varying structure and charge.
Effect of Mg Alloying Addition on Dissolution Behavior of Oxide Films in Al-Si-Mg Alloys
Authors: Pech-Canul Maximo A. , Pech-Canul Martin I. , Echeverría Marbella , Montoya-Dávila Miguel
Published: September 2007

Cyclic polarization measurements were carried out for Al-10%Si- X%Mg (X: 3%, 6% and 9.5%) alloys in borate solutions with and without additions of 50 mM NaCl. The voltammetric response exhibited some features of oxide film growth consistent with the high field conduction model. However, higher currents and distortions in the voltammetric wave shape compared to those for pure Al were ascribed to a possible incorporation of alloying elements in the oxide film, rendering it more defective, and to the strong electrochemical activity of Mg2Si particles
The Apparent CPE Behavior of a Disk Electrode with Faradaic Reactions: A Global and Local Impedance Analysis
Authors: Huang Vicky , Vivier Vincent , Orazem Mark E. , Pebere Nadine , Tribollet Bernard
Published: September 2007

Geometry-induced current and potential distributions modify both the global and local impedance response of a disk electrode subject to Faradaic reactions. The problem was treated for both linear and Tafel kinetic regimes. At frequencies above the characteristic frequency for the Faradaic reaction, the global impedance response has a quasi-CPE character, but with a CPE coefficient α that is a function of both dimensionless frequency K and dimensionless current density J. For small values of J, α approached unity; whereas, for larger values of J, α reached values near 0.78. While the calculated global impedance was purely capacitive, the local impedance has high-frequency inductive loops. The local impedance is influenced by the local Ohmic impedance, which has complex behavior near a characteristic dimensionless frequency K = 1.
Macroscopic and Local Electrochemical Studies of Austempered Ductile Iron in Various Aqueous Solutions
Authors: Krawiec Halina , Vignal Vincent , Banaś Jacek
Published: September 2007

The present paper aims at demonstrating the potentialities of the electrochemical microcell technique and surface analysis methods for studying the electrochemical behaviour of austempered ductile iron at the microscale. The objective is to identify precursor sites and to understand basic mechanisms leading to localized dissolution. These Experiments, which were conducted both in 1M NaClO4, pH=10 and 1M NaClO4, pH=3, are compared to the results obtained at the macroscale.
The Effect of Phthalate/Sulphonic Acid Ester Plasticisers on the TiO2 Photocatalyzed Degradation of PVC
Authors: Martin Glyn P. , Robinson Andrew , Worsley David A.
Published: September 2007

The effects of two plasticizers, one phthalate and one sulfonic acid ester, on the photodegradation of TiO2 pigmented polyvinylchloride (PVC) films are reported. The loading of each plasticizer was altered in the range 0 - 70% relative to the PVC and the effects on the rates of photomineralization were determined using a closed loop flow system to detect the carbon dioxide evolution. All plasticizer additions lead to an initial acceleration in CO2 evolution over the non-plasticized cases. Non-plasticized films show a marked acid catalysis due to HCl evolution which leads to an acceleration in the rate of oxidation with time. Following initial rapid oxidation of pre- adsorbed plasticizer, the phthalate systems demonstrated a reduced rate of CO2 production and no acid catalysis. The sulfonic acid ester plasticizer is broken down to produce sulfonic acid and sulfuric acid fragments which are sufficiently acidic to catalyze the TiO2 when plasticizer loadings are >50%. The carboxylic acid fragments from the phthalates seem incapable of catalysis even at the highest levels used in this work.
The Study of Electrochemical Cyclisation of Propargyl Derivatives using [Ni(tmc)]Br2 as Catalyst in Microemulsions
Authors: Evans A. , Esteves A.P. , Medeiros Maria Jose , Neves C.S.S. , Pletcher D.
Published: September 2007

The reductive intramolecular cyclisation of ethyl 2-bromo-3- (3′,4′- dimethoxyphenyl)-3-propargyloxy-propanoate (1) catalysed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11- tetraazacyclotetradecane) nickel(I), [Ni(tmc)]+, in microemulsions made with cationic and anionic surfactants has been investigated by cyclic voltammetry and controlled-potential electrolysis. During controlled-potential electrolyses of Ni(II) complexes in the presence of bromopropargyloxy derivative 1, catalytic reduction of the latter proceeds via cleavage of the carbon-bromine bond to form a radical intermediate that undergoes cyclization to afford the substituted tetrahydrofurans.
Reduction Potential Shifts Due to Active Site and Surface Mutations of Yeast Cytochrome c Peroxidase
Authors: DiCarlo Cory M. , Vitello Lidia , Erman James
Published: September 2007

Twenty two reduction potentials of yeast cytochrome c peroxidase (CcP) mutants were determined at pH 7.0 in order to determine the effect of both surface and heme pocket mutations on the Fe(III)/Fe(II) redox couple of CcP, as well as to determine redox potential range that could be obtained through enzyme point mutations. The mutations include variants in the distal and proximal heme pockets as well as on the enzyme surface and involve single, double, and triple point mutations. Compared to the reduction potential of the wild- type enzeme, both negative and positive shifts in the reduction potential were observed, spanning a range of 113 mV. The His-52→Asn mutation gave the most negative potential, -259 mV, while a triple mutant in which the three distal pocket residues, Arg-48, Trp-51, and His-52, were all converted to leucine residues gave the most positive potential, -146 mV.
Glucose Oxidation on Au-Pt Nanoparticles in a Membrane-Less Biofuel Cell
Authors: Habrioux Aurelien , Servat Karine , Kokoh Boniface , Alonso-Vante Nicolas
Published: September 2007

The electrical performances of a membrane-less glucose/O2 biofuel cell was measured, using a biocathode composed of laccase co-immobilized with 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS2-) on the external face of a carbon porous tube, and Au-Pt alloy nanoparticles as anode. A 40 wt. % Au-Pt/C anode catalyst was dispersed in an ultrasonically homogenized ink to be immobilized on the inner face of a carbon tube by painting. Inserting the biocathode into the anode, which has a large internal diameter, assembled the cell. O2 diffuses by porosity through the inner carbon tube to react with laccase, while the top and the bottom of the cell are sealed with two Teflon gaskets. The electrolyte (phosphate buffer 0.2 M pH 7.4) containing 10 mM glucose was analyzed by ionic chromatography with a ternary gradient of elution necessary to separate the remaining glucose from gluconic, glucuronic and glucaric acids, which were the detected reaction products.
Nanocomposites for Water Treatment
Authors: Jones Kimberley , Boxall Colin , McCabe Richard , Shaw David , Buck Malcolm
Published: September 2007

The treatment of waste water involves, amongst other processes, the removal of heavy metal ion pollutants and/or organic contaminants. As one component of a potential aluminosilicate nanocomposite for water treatment, we have demonstrated the effectiveness of using Maghemite (γ-Fe2O3) as a photocatalyst for the reduction of the aqueous pollutant chromium(VI) to chromium(III) in the presence of a sacrificial organic reductant. Maghemite has the twin advantages of being a photocatalyst that exhibits strong absorbance in the visible region of the spectrum and of being magnetic, so facilitating post processing solid/liquid separation. During this study, a simple, robust, calibrationless potentiometric technique for monitoring the concentration of chromium(VI) was developed. This method allowed the photocatalytic reduction of Cr(VI) to be observed in real-time with no sample pre-treatment.
Effects of TiCl4-Based PECVD-Ti/CVD-TiN Barrier Layers on the BF2-Doped Si for Contact Plug Technology
Authors: Huang Tsai-Yu , Liang Wen-Ping , Su Kuo-Hui , Wu Chang-Rong , Lin Yu-Chang , Satoshi Wakabayashi , Lin Jeng Ping
Published: September 2007

We have performed the investigation of Ti/TiN barrier layers deposited by PECVD of Ti and CVD of TiN using TiCl4 as a reactant on a heavily boron doped Si substrate. High contact resistance arose from both the boron out-diffusion, and high chlorine content in the Ti film with respect to the relatively high, and low process temperatures of PECVD-Ti deposition, respectively. In the optimized PECVD-Ti process condition with the satisfied boron dose in the Si substrate, comparable yields can be achieved with that using the 110nm deep trench Dynamic Random Access Memory (DRAM) technology with PVD-Ti method. Furthermore, using PECVD-Ti/CVD-TiN method for the contact metallization, it can obtain a uniform thickness of liner in the hole-type contact with aspect ratio to 6.
Electrochemical Oxidation of Mesoporous Silicon: Structural and Morphology Properties of the Obtained ox-porSi Material
Authors: Pastor Ester L. , Ayucar Jose Angel , Curiel-Esparza Jorge , Matveeva Eugenia S. , Salonen Jarno , Letho Vesa P.
Published: September 2007

Morphological and structural changes in porous silicon por-Si grown on differently doped Si wafers under anodic oxidation in phosphoric acid were studied. The two degrees of oxidation were confirmed: slighter (pore walls) and stronger (bulky) oxidation. Slighter oxidized por-Si does not experience any structural or morphological changes but chemical composition of the pore walls is gradually changed to Si-OH terminations. Stronger oxidation is accompanied by progressive morphological and structural transformations. Conductivity of the porous layer plays a significant role in the observed behavior. In less doped samples only a stronger oxidation started at the bottom of the porous layer is found. Porous layer becomes electrically separated from the Si wafer (electrode) and surface Si-Hx groups are preserved. Thus, doping level and conductivity of the Si wafer determines a spatial distribution of the porous electrode/ electrolyte interface and possibility to conserve native chemical composition of por-Si after electrochemical oxidation.
Water Vapor Absorption on Nanostructured Carbide Derived Carbon (CDC)
Authors: McNallan Michael , Gupta P.
Published: September 2007

In this work, carbide derived carbon (CDC) layers were synthesized on SiC and kept isolated from the environment until exposed to controlled water vapor atmospheres, so that the effects of water vapor pressure on the absorption could be quantified. The effects of high temperature hydrogen treatment are also described. CDC samples after chlorination are very hygroscopic, absorbing up to 35% of their weight in water in low humidity environments.
Structure Effect of Si-Based Powder on Cycle Performance of Lithium Ion Battery
Authors: Shieh Dt , Yang Mo-Hua , Guo Zheng-Zhao , Hsieh Ping-Hsun , Tsao Shen , Lin M.W. , Liu Wei-Ren , Wu N.L.
Published: September 2007

In this study, an inactive material (Ni) is introduced into Si for buffering the volume change causing by the lithium insertion and de-insertion. A porous structure is designed for further reducing of the volume change. The surface-porous structure SiNi powder is prepared by gas atomization method and wet-etching in an acidic solution, which shows positive effects on cycle performance, high capacity and the efficiency at the first cycle. Coated a carbon layer onto SiNi powders by CVD process can further improve the cycle performance by preventing structure collapse.
Electrochemical Properties of Carbon Nanotube/Silicon Composites for Anode of Li-Ion Battery
Authors: Eom Jiyong , Kwon Hyuksang
Published: September 2007

Multi-walled carbon nanotube (MWNT)/silicon composites with different weight ratios were produced from purified MWNTs and Si powder by high energy ball-milling and then electrochemically inserted with lithium. The charge/discharge properties for the ball-milled MWNT/Si composite anodes were found to be very sensitive to the weight ratio of MWNT to Si. The highest Crev and lowest Cirr of the composite anode were measured to be 1770 mAh/g and 469 mAh g-1 respectively at the ratio of MWNT0.5/Si0.5. During charging/discharging processes, most of Li ions were inserted into the ball-milled MWNT/Si composites by alloying with Si particles at potentials positive to 0.25 V vs. Li, and extracted from the ball-milled MWNT/Si composites by dealloying with Si particles at potentials positive to 0.5 V vs. Li. The good capacity and cycle performance of the MWNT0.5/Si0.5 composite anode is due primarily to the fact that MWNTs encapsulating fine Si particles by strong contact prevent Si particles from electrical insulation caused by the crumbling of the Si particles.
Modeling Parametric Uncertainty Using Polynomial Chaos Theory
Authors: Santhanagopalan Shriram , White Ralph E.
Published: September 2007

Every mathematical model of a battery has one or more parameters, which need to be obtained from experimental data. However, most models do not allow for the fact that the estimated parameter values have a factor of uncertainty associated with them - that may originate from non-uniformities in the material property or the scatter in the experimental data among other factors. In the present work, a generalized procedure to incorporate uncertainty in parameter values based on the Polynomial Chaos Theory (PCT) is presented. The particle size inside the carbon electrode of a lithium ion cell is assumed to have a Gaussian distribution of a known mean and standard deviation. The effect of this distributed parameter value on the discharge curve is illustrated as an example.
Improving Capacity and Thermal Degradation Characteristics of Li/(CFx)n Cells using Anion Binding Agent in the Electrolyte
Authors: Nagasubramanian G.
Published: September 2007

At Sandia National Laboratories we are exploring ways to improving capacity and the thermal degradation characteristics of Li/(CFx)n cells. We prepared (CFx)n electrodes with two different thicknesses and tested them in coin cells in conventional organic electrolytes and in Sandia developed electrolyte containing LiF complexed with an anion-binding- agent (ABA) as Li salt. Both the delivered capacity and the thermal characteristics of the thicker electrodes (15 mils thick) that have Teflon as binder are better in ABA containing electrolyte. For example, 2016 coin cells containing ABA and LiF (despite low conductivity) showed ~ 10% higher capacity than those containing the highly conductive electrolyte (HCE). Similar trend was observed for cells aged 4 days at 80oC and tested at 25oC. However, with thinner electrodes (1.5 -2 mil thick) that have PVDF as binder the delivered capacity was similar in the different electrolytes but the thermal behavior is better in ABA containing electrolyte
Investigation of Copper Processing in the Damascene Process by Electrochemical Impedance Analysis.
Authors: Gabrielli Claude , Moçotéguy Philippe , Perrot Hubert , Zdunek Alan
Published: September 2007

Microelectronics is a new field of interest for electrochemistry as this technology has adopted copper electrodeposition to build the interconnections in microcircuits by means of the so-called Damascene process. In this work, EIS was used to investigate copper deposition in sulfuric-sulfate medium in presence of organic additives. A model was proposed for the system and it was tested in various experimental conditions. In particular, it was shown that EIS could be used to monitor the ageing of the copper plating bath.
Development of Manufacturable Solutions for the Direct Plating of Copper on Robust ALD-Grown Barriers
Authors: Kumar Sumit , Greenslit Daniel , Eisenbraun Eric
Published: September 2007

A novel plasma enhanced atomic layer deposition (PEALD)-grown mixed-phase/nano-laminate barrier has been developed which combines the robust barrier properties of TaN with direct plate characteristics of Ru. Preliminary investigation indicates that Ru:TaN layers as thin as 5 nm can be designed to act both as robust copper barrier and as a copper direct plating layer. Direct plated copper films were found to exhibit preferred (111) orientation with the use of medium acid level electrolyte (0.8M H2SO4) and higher plating current density (10 mA/cm2) during the copper electrochemical deposition process. Also, (111) texture in the direct plated copper films improved as Ru content in the mixed-phase barrier was increased. Direct plated copper films were found to possess larger grain size characteristics as compared to copper electroplated on PVD copper seed. The filling characteristics in sub-65 nm features were found to be equivalent for seeded copper and Ru:TaN barrier films without a seed layer.
Selective Electroless Ni-Based Capping Layer on Cu Gate Electrode of TFT-LCD
Authors: Chang Shu-Ya , Hsu Wen-Chi , Wan Chi-Chao , Wang Yung-Yun
Published: September 2007

In this study, electroless Ni-based capping layers were selectively deposited on Cu surface without Pd activation. The Pd-free electroless process can eliminate possible Pd diffusion into Cu lines that causes an increase in sheet resistance of Cu. Film composition, surface morphology, film structure, chemical state and barrier function of electroless Ni-based films were discussed in our present work. The developed NiWMoB films have superior thermal stability compared with NiWB film. In addition, the depth profile suggested Cu diffusion was not observed after thermal treatment, rendering it a promising candidate as capping layer.
Photocatalytic Initiation of Electroless Deposition
Authors: Galea Sarah , Boxall Colin , Goodall Philip , Woodbury Simon
Published: September 2007

We report a one step Photocatalytically Initiated Electroless Deposition (PIED) process that allows for the photogeneration of coherent, conducting metal layers on semiconductor- sensitised insulator surfaces. Layers of silver have been generated on mesoporous TiO2 layers and nanoparticulate TiO2 coated quartz and PVDF membranes. Deposition occurs only onto areas of the substrate both sensitised with TiO2 and illuminated with light. Morphology of the resultant layer is dependant upon the nucleation density occurring during the primary photocatalytic stage of PIED. Electrogravimetry indicates that PIED results in an enhanced rate of metal nucleation on TiO2 surfaces, compared to bare metal. The mixed potential measured at TiO2-coated electrodes shifts by ~-75 - - 100 mV upon illumination during PIED, resulting in more-facile semiconductor-to-solution electron transfer, so explaining the enhanced rate of nucleation in the light. PIED provides a cheaper, environmentally cleaner and more controllable option than the traditional technique of plating onto dielectric surfaces.
Electrolyte Effect on Nanotubes Properties
Authors: Davis Despina , Pinisetty Dinesh , Prabhakar Aparna , Moldovan Monica , Young David P. , Devireddy Ram , Murphy Michael , Podlaha Elizabeth
Published: September 2007

The ability to electrodeposit magnetic (CoNiFeCu) and semiconductor (Bi2Te3) nanotubes was demonstrated from two different electrochemical systems. Electrodeposited multilayered CoNiFeCu/Cu nanotubes were fabricated by pulsing the applied potential. The electrolyte temperature affected the tube formation and the nanotubes giant magnetoresistance (GMR) saturation field. Both p/n-type Bi2Te3 alloy nanotubes were deposited under constant potential from different electrolyte concentrations and component ratios. We report the Seebeck coefficient measurement method for Bi2Te3 alloy nanotubes obtained by electrodeposition.
Parameter Effects for the Growth of Thin Porous Anodic Aluminum Oxides
Authors: Yim Setha , Bonhote Christian , Lille Jeffrey , Wu Tsai-Wei
Published: September 2007

Production of porous anodic aluminum oxide (AAO) films from 100 nm evaporated aluminum (on silicon) was studied in order to determine the effects of voltage, temperature and acid concentration on the diameter, interpore distance, and long-range order of the holes. The largest change observed was found in the voltage experiments using concentrated sulfuric acid (H2SO4), where the voltage was varied from 10-60V. Pores were produced even at low voltages with 30 nm interpore distance. This aforementioned arrangement has allowed for the smallest AAO pores to be found in any such experiment to date.
Mathematical Modeling of Li/CFx-SVO Batteries
Authors: Gomadam Parthasarathy , Merritt Donald , Scott Erik , Schmidt Craig , Skarstad Paul , Weidner John W.
Published: September 2007

This document describes a first-principles-based mathematical model developed to predict the voltage-capacity behavior of batteries having hybrid cathodes comprising a mixture of carbon monofluoride (CFx) and silver vanadium oxide (SVO). These batteries typically operate at moderate rates of discharge, lasting several years. The model presented here is an accurate tool for design optimization and performance prediction of batteries under current drains that encompass both the application rate and accelerated testing.
Novel Energy Storage System Based on an Attraction Between Graphitic Carbon and Anion
Authors: Yoshio Masaki , Wang Hongyu , Ishihara Tatsumi , Nakamura Hitoshi
Published: September 2007

Traditional EDLC using the symmetrical double activated carbon (AC) electrodes is limited by the low energy density. We replaced the positive AC electrode by a graphitic carbon electrode in the new type of capacitor. The energy density can be remarkably enhanced. The storage mechanism of anions at the graphitic carbon cathode is ascribed to a specific interaction between the anions and graphitic carbon.
Investigation of LixCoO2 Phases Produced by Heat Treatment of Delithiated LiCoO2 Powders
Authors: Yi Tanghong , Kombolias Mary , Gabrisch Heike
Published: September 2007

LiCoO2 is used as a cathode material in most commercial lithium- ion batteries. Of the phases formed upon Li-removal the P3 phase has been only reported in the chemically delithiated materials. In this paper we compared LixCoO2 produced by chemical and electrochemical methods. P3 phase was found in both chemically and electrochemically delithiated specimens. We investigate the phases formed at elevated temperatures by X-ray diffraction and electron microscopy. Above approximate 200{degree sign}C LixCoO2 decomposed into fine Co3O4 and LiCoO2 particles
Investigation on Cycling Stability of Mn-Containing Oxide Supercapacitors
Authors: Wu Nae-Lih Nick , Kuo S. L.
Published: September 2007

The mechanism leading to capacitance fading upon cycling of MnO2·nH2O and MnFe2O4 supercapacitors have been studied by using electrochemical characterization and in-situ synchrotron X-ray diffraction. For both supercapacitors, the cycling stability was found to be significantly increased by either reducing charge/discharge rate or increasing dilution ratio with acetylene carbon additive in the electrode. In addition, MnFe2O4 exhibits smaller volume variation during charge/discharge, and its electrodes show superior cycling stability than the MnO2·nH2O ones. It is proposed that the capacitance fading mainly arises from mechanical failure of the electrode structure caused by the volume variation-induced stress, leading to losing contact between the oxide particles and conducting acetylene black and/or detachment of the oxide particles from the electrode matrix.
Identification of Allylamine and Allylalcohol Adsorbate on Hydrogen-terminated Si(111)
Authors: Yamada Taro , Yokomori Ryo , Shirasaka Kaoru , Kato Hiroyuki S. , Kawai Maki
Published: September 2007

The adsorbates formed by ultraviolet photo-assisted adsorption of allylamine (CH2=CHCH2-NH2) and allylalcohol (CH2=CHCH2- OH) on hydrogen-terminated Si(111) surfaces were examined by vibrational analysis using high-resolution electron energy loss spectroscopy (HREELS). The spectra exhibit the stretching signals for N-H and O-H, indicating the survival of functional groups -NH2 and -OH within the precursor molecules on the adsorbed layers. For the allylamine adsorbate, delivery of gaseous ketene (CH2=C=O) resulted in formation of amide (CH3CONH-) adsorbate. The allylamine adsorbate was evidently functional for peptide-bond formation. These monolayers are prospective materials for usage in nanometer-scale fabrication, chemical functionalization and biochemical analysis.
Analyses of Ternary Alloy Plating Systems by a New Kinetic Model
Authors: Kuehnlein Holger H. , Plieth Waldfried
Published: September 2007

A new model for the electrochemical alloy deposition is applied for several ternary plating systems. This model is treating the interaction of the electrode surface sites and the electrolyte metal ions. The discussed concept is based on the finite Markov chain theory and gives the first analytical relationship between a binary alloy composition and the metal ion concentrations of the electrolyte. The elementary parameters gAB-1 and gBA-1, also called selectivity constants, are determined from experimental data of binary alloy depositions. The selectivity constants give a quantified description of the competitive adsorption kinetic of metal ions at different kink site positions of an alloy electrode. Thus this basic information from different binary couples can be applied to give a valid prediction for a resulting ternary alloy composition. Beside the calculations of the expected alloy contents also additive and temperature influences are discussed in terms of changed selectivity constants.
Adsorption of camphor at Bi(111) electrode
Authors: Kallip Silvar , Kasuk Heili , Grozovski Vitali , Lust Enn
Published: September 2007

Impedance spectroscopy and in situ STM methods have been used for investigation of the camphor adsorption at the electrochemically polished Bi(111) electrode from weakly acidified Na2SO4 base electrolyte aqueous solution. The influence of the electrode potential on the adsorption kinetics and camphor adsorption layer structure on Bi(111) has been demonstrated. In the region of the capacitance pit in the differential capacitance vs. electrode potential curve the so- called heterogeneous adsorption step is the rate determining stage for camphor adsorption at the electrochemically polished Bi(111) electrode, but not diffusion as usually assumed. It was found that the stable adsorbate adlayer detectable by using the in situ STM method has been observed only at the positively charged electrode surface, where the weak co-adsorption of SO42- anions and camphor molecules is possible. At the weakly negatively charged Bi(111) electrode surface there are only physically adsorbed camphor molecules forming the compact adsorption layer.
Beneficial effect of heme oxygenase-1 expression on myocardial ischemia-reperfusion involves an increase in adiponectin in mildly diabetic rats
Authors: L'Abbate Antonio , Neglia Danilo , Vecoli Cecilia , Novelli Michela , Ottaviano Virginia , Baldi Simona , Barsacchi Renata , Paolicchi Aldo , Masiello Pellegrino , Drummond George S. , McClung John A. , Abraham Nader G.
Published: September 2007

Transient reduction in coronary perfusion pressure in the isolated mouse heart increases microvascular resistance (paradoxical vasoconstriction) by an endothelium-mediated mechanism. To assess the presence and extent of paradoxical vasoconstriction in hearts from normal and diabetic rats and to determine whether increased heme oxygenase (HO)-1 expression and HO activity, using cobalt protoporphyrin (CoPP), attenuates coronary microvascular response, male Wistar rats were rendered diabetic with nicotinamide/streptozotocin for 2 wk and either CoPP or vehicle was administered by intraperitoneal injection weekly for 3 wk (0.5 mg/100 g body wt). The isolated beating nonworking heart was submitted to transient low perfusion pressure (20 mmHg), and coronary resistance (CR) was measured. During low perfusion pressure, CR increased and was associated with increased lactate release. In diabetic rats, CR was higher, HO-1 expression and endothelial nitric oxide synthase were downregulated, and inducible nitric oxide synthase and O2− were upregulated. After 3 wk of CoPP treatment, HO activity was significantly increased in the heart. Upregulation of HO-1 expression and HO activity by CoPP resulted in the abolition of paradoxical vasoconstriction and a reduction in oxidative ischemic damage. In addition, there was a marked increase in serum adiponectin. Elevated HO-1 expression was associated with increased expression of cardiac endothelial nitric oxide synthase, B-cell leukemia/lymphoma extra long, and phospho activator protein kinase levels and decreased levels of inducible nitric oxide synthase and malondialdehyde. These results suggest a critical role for HO-1 in microvascular tone control and myocardial protection during ischemia in both normal and mildly diabetic rats through the modulation of constitutive and inducible nitric oxide synthase expression and activity, and an increase in serum adiponectin.
In vivo genetic profiling and cellular localization of apelin reveals a hypoxia-sensitive, endothelial-centered pathway activated in ischemic heart failure
Authors: Sheikh Ahmad Y. , Chun Hyung J. , Glassford Alexander J. , Kundu Ramendera K. , Kutschka Ingo , Ardigo Diego , Hendry Stephen L. , Wagner Roger A. , Chen Mary M. , Ali Ziad A. , Yue Patrick , Huynh Diem T. , Connolly Andrew J. , Pelletier Marc P. , Tsao Philip S. , Robbins Robert C. , Quertermous Thomas
Published: September 2007

Signaling by the peptide ligand apelin and its cognate G protein-coupled receptor APJ has a potent inotropic effect on cardiac contractility and modulates systemic vascular resistance through nitric oxide-dependent signaling. In addition, there is evidence for counterregulation of the angiotensin and vasopressin pathways. Regulatory stimuli of the apelin-APJ pathway are of obvious importance but remain to be elucidated. To better understand the physiological response of apelin-APJ to disease states such as heart failure and to elucidate the mechanism by which such a response might occur, we have used the murine model of left anterior descending coronary artery ligation-induced ischemic cardiac failure. To identify the key cells responsible for modulation and production of apelin in vivo, we have created a novel apelin-lacZ reporter mouse. Data from these studies demonstrate that apelin and APJ are upregulated in the heart and skeletal muscle following myocardial injury and suggest that apelin expression remains restricted to the endothelium. In cardiac failure, endothelial apelin expression correlates with other hypoxia-responsive genes, and in healthy animals both apelin and APJ are markedly upregulated in various tissues following systemic hypoxic exposure. Experiments with cultured endothelial cells in vitro show apelin mRNA and protein levels to be increased by hypoxia, through a hypoxia-inducible factor-mediated pathway. These studies suggest that apelin-expressing endothelial cells respond to conditions associated with heart failure, possibly including local tissue hypoxia, and modulate apelin-APJ expression to regulate cardiovascular homeostasis. The apelin-APJ pathway may thus provide a mechanism for systemic endothelial monitoring of tissue perfusion and adaptive regulation of cardiovascular function.
Rottlerin causes pulmonary edema in vivo: a possible role for PKCδ
Authors: Klinger James R. , Murray Josh D. , Casserly Brian , Alvarez Diego F. , King Judy A. , An Steven S. , Choudhary Gaurav , Owusu-Sarfo Akua N. , Warburton Rod , Harrington Elizabeth O.
Published: September 2007

In the present study, we assessed the effects of chemical inhibitors shown to be selective for protein kinase C (PKC) isoforms on lung barrier function both in vitro and in vivo. Rottlerin, a purported inhibitor of PKCδ, but not other chemical inhibitors, dose dependently promoted barrier dysfunction in lung endothelial cells in vitro. This barrier dysfunction correlated with structural changes in focal adhesions and stress fibers, which were consistent with functional changes in cell stiffness. To determine whether the effects noted in vitro correlated with changes in intact lungs, we tested the effects of rottlerin in the formation of pulmonary edema in rats using both ex vivo and in vivo models. Isolated, perfused lungs demonstrated a significant increase in filtration coefficients on exposure to rottlerin, compared with vehicle-treated lungs, an effect that correlated with increased extravasation of Evan's blue dye (EBD)-conjugated albumin. Additionally, compared with vehicle, the ratio of the wet lung weights to dry lung weights was significantly greater on exposure of animals to rottlerin; rottlerin also produced a dose-dependent increase in EBD extravasation into the lungs. These effects on lung edema occurred without any increase in right ventricular pressures. Microscopic assessment of edema in the ex vivo lungs demonstrated perivascular cuffing, with no evidence of septal capillary leak, in rottlerin-exposed lungs. Taken together, rottlerin increases barrier dysfunction in pulmonary endothelial cell monolayers and causes pulmonary edema in rats; results suggestive of an important role for PKCδ in maintaining lung endothelial barrier function.
Human blood neutrophil responses to prolonged exercise with and without a thermal clamp
Authors: Laing Stewart J. , Jackson Anna R. , Walters Robert , Lloyd-Jones Enid , Whitham Martin , Maassen Norbert , Walsh Neil P.
Published: September 2007

The purpose of this study was to investigate the effects of prolonged exercise with and without a thermal clamp on neutrophil trafficking, bacterial-stimulated neutrophil degranulation, stress hormones, and cytokine responses. Thirteen healthy male volunteers (means ± SE: age 21 ± 1 yr; mass 74.9 ± 2.1 kg; maximal oxygen uptake 58 ± 1 ml·kg−1·min−1) completed four randomly assigned, 2-h water-immersion trials separated by 7 days. Trials were exercise-induced heating (EX-H: water temperature 36°C), exercise with a thermal clamp (EX-C: 24°C), passive heating (PA-H: 38.5°C), and control (CON: 35°C). EX-H and EX-C was comprised of 2 h of deep water running at 58% maximal oxygen uptake. Blood samples were collected at pre-, post-, and 1 h postimmersion. Core body temperature was unaltered on CON, clamped on EX-C (−0.02°C), and rose by 2.23°C and 2.31°C on EX-H and PA-H, respectively. Exercising with a thermal clamp did not blunt the neutrophilia postexercise (EX-C postexercise: 9.6 ± 1.1 and EX-H postexercise: 9.8 ± 1.0 × 109/liter). Neutrophil degranulation decreased ( P < 0.01) similarly immediately after PA-H (−21%), EX-C, and EX-H (−28%). EX-C blunted the circulating norepinephrine, cortisol, granulocyte-colony stimulating factor, and IL-6 response ( P < 0.01) but not the plasma epinephrine and serum growth hormone response. These results show a similar neutrophilia and decrease in neutrophil degranulation after prolonged exercise with and without a thermal clamp. As such, the rise in core body temperature does not appear to mediate neutrophil trafficking and degranulation responses to prolonged exercise. In addition, these results suggest a limited role for cortisol, granulocyte-colony stimulating factor, and IL-6 in the observed neutrophil responses to prolonged exercise.