bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Quantitative Approach for Evaluating Contact Mechanics of Meniscal Replacements
Authors: Linder-Ganz E. , Elsner J. J. , Danino A. , Guilak F. , Shterling A.
Published: October 2009

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees (n=3). Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures—implant-dislocation and implant-impingement on the ligaments—were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.
Disproportionate sales of crime guns among licensed handgun retailers in the United States: a case–control study
Authors: Wintemute G J
Published: October 2009

Objective:

To determine risk factors among licensed firearm retailers for disproportionate sales of handguns that are later subjected to ownership tracing, generally after use in crime.

Design:

Case–control; the study period was 1998–2003. Cases were all eligible firearm retailers whose handguns were later traced at a rate that significantly (p<0.05) exceeded the expected value. Controls were a 4:1 random sample of the remainder. Data were obtained from sales and tracing records for 1998–2003 and site visits conducted August–December, 2004.

Subjects and setting:

60 cases and 240 controls, from the 573 retailers in California selling ⩾ 50 handguns annually during the study period.

Main outcome measure:

Status as a case. Odds ratios were used to measure relative risk.

Results:

In multivariate analyses, cases had larger sales volumes, sold inexpensive handguns more often, had a higher percentage of sales denied because the prospective purchasers were prohibited from owning firearms, and were more likely to be in an urban area, in or near a city with a policy of tracing all recovered crime guns. The effects of several risk factors, including status as a pawnbroker and sales to law enforcement personnel, appeared to be mediated by purchaser characteristics for which denied sales are a proxy measure.

Conclusions:

A number of factors—most of them characteristics of the retailers or of their handgun purchasers, and most of them available in existing data—were linked to disproportionate sales of handguns that are later used in crime.
Validation of a HOME Injury Survey
Authors: Phelan K J , Khoury J , Xu Y , Lanphear B
Published: October 2009

Background:

There are no validated observational surveys to assess injury hazards in the home environment.

Objective:

To evaluate the reproducibility and reliability of a survey quantifying home injury hazards for children.

Methods:

A nested cohort of children in the intervention arm of the Home Observations and Measures of the Environment (HOME) Study trial were analysed. The number and density of hazards were quantified by research assistants in the homes of participants at a baseline visit (BHV) for four high-risk rooms (kitchen, main activity room, child’s bathroom and child’s bedroom) and stairways and later at an intervention planning visit (IPV) for the four high-risk rooms and entire household. Statistical analysis included Pearson correlation, Bland–Altman analysis of agreement, analysis of variance and κ statistics.

Results:

There were163 households with measurements at BHV and IPV. The number and density of hazards for the four high-risk rooms correlated significantly between BHV and IPV (r = 0.50 and 0.75, respectively). The number and density of hazards for the four high-risk rooms correlated significantly with that for the whole household at the IPV (r = 0.17 and 0.52, respectively). The number of injury hazards was significantly higher in the kitchen than in the other high-risk rooms, whereas density was highest in the child’s bathroom. Inter-rater reliability between research assistants, as measured by the κ statistic, was excellent with a mean of 0.81.

Conclusions:

The HOME Injury Survey was a reliable and replicable tool for quantifying residential injury hazards. The density of injury hazards was a more stable and valid measure than the number of injury hazards.
Characteristics of adult male and female firearm suicide decedents: findings from the National Violent Death Reporting System
Authors: Kaplan M S , McFarland B H , Huguet N
Published: October 2009

Objective:

To examine the risk factors and precipitating circumstances associated with firearm suicide.

Methods:

Data from the restricted National Violent Death Reporting System (2003–6) for 25 491 male and female suicide decedents aged 18 and older were analysed by multiple logistic regression to estimate the relative odds of firearm use with 95% CIs.

Results:

Firearms were often used in male (58.1%) and female (31.2%) suicides. Among male decedents, older age, veteran status, residing in areas with higher rates of firearm availability, raised blood alcohol concentration, acute crisis and relationship problems were all associated with firearm use. Conversely, men with a diagnosis of a mental health problem, a history of suicide attempts or alcohol problems had lower odds of firearm use. Among female decedents, factors with a significant effect on firearm use included: being older, married, white and a veteran; residing in areas with higher rates of firearm availability; having an acute crisis; having experienced the death of a relative or friend; being depressed; and having relationship problems. Of note, women who had a treated DSM-IV-diagnosed problem, previous suicide attempts and physical health problems were less likely to use firearms.

Conclusions:

These findings challenge the conventional view that those who are severely depressed and suicidal are prone to highly lethal methods, such as firearms. Rather, firearms users may be reacting to acute situations.
Innovation in qualitative interviews: “Sharing Circles” in a First Nations community: Table 1
Authors: Rothe J P , Ozegovic D , Carroll L J
Published: October 2009

There is growing recognition that different research approaches are necessary to understand the complex interaction between individual and social processes that contribute to risk-taking and injuries. Therefore, qualitative studies have an important role in injury prevention research. This article describes qualitative research in general and outlines some of the ways qualitative research can add to our understanding of injury. It also describes the role, format and methods of interviews (person-to-person and focus groups) commonly performed in qualitative studies, and proposes a novel approach to interviewing that has special relevance and value in injury research with indigenous populations. This methodology adapts focus group methods to be consistent with the goals and procedures of the traditional First Nations communities’ Sharing Circles. This adaptation provides a culturally appropriate and sensitive method of developing a deep and broad understanding of indigenous participants’ verbal descriptions of their feelings, their experiences and their modes of reasoning. After detailing of this adaptation of the Sharing Circle as a vibrant and vital interview and analysis method, the use of Sharing Circle interview methodology will be illustrated in a study investigating how an Alberta First Nations community experiences and deals with disproportionate levels of injuries arising from impaired driving, outlining important findings uncovered using this novel interviewing method. These findings have been informative to First Nations communities themselves, have informed policy makers provincially and nationally, and have instigated culturally appropriate intervention techniques for Canadian First Nations communities.
Histories including number of falls may improve risk prediction for certain non-vertebral fractures in older men
Authors: Faulkner K A , Chan B K S , Cauley J A , Marshall L M , Ensrud K E , Stefanick M L , Orwoll E S
Published: October 2009

Objective:

To determine whether information on number of falls on a falls history screen predicts risk of non-vertebral and hip fracture.

Methods:

A cohort of 5995 community-dwelling men aged 65 years and older (mean 73.7) was followed over 7.2 years for incident non-vertebral fractures. Cox proportional hazard models were used to calculate hazard ratios (HRs) (95% CI) for incident fracture comparing a history of one and two or more falls with no falls. Models were adjusted for age, clinic, body mass index, height, femoral neck bone mineral density and whether the participant had a non-trauma fracture after the age of 50. p⩽0.05 was considered to denote significance.

Results:

There were 498 incident non-vertebral fractures (15.5/1000 person-years) and 121 incident hip fractures (3.6/1000 person-years). Compared with men who had had no falls, the risk of non-vertebral and lower extremity fractures was significantly higher in men with one fall (HR = 1.54 (95% CI 1.22 to 1.96) and 1.91 (95% CI 1.36 to 2.67), respectively) and men with two or more falls (HR = 1.81 (95% CI 1.40 to 2.34) and 1.79 (95% CI 1.23 to 2.61), respectively). The risk of head/chest, upper extremity and hip fractures (HR = 2.22 (95% CI 1.42 to 3.49), 2.08 (95% CI 1.01 to 4.28) and 1.79 (95% CI 1.07 to 2.98), respectively) was significantly higher for two or more falls than no falls; however, equivalent risks were not significantly higher (HR = 1.36 (95% CI 0.88 to 2.20), 1.55 (95% CI 0.74 to 3.25) and 1.41 (95% CI 0.87 to 2.27), respectively) comparing men with one fall versus no falls.

Conclusion:

Expanding clinical screens to include an assessment of fall frequencies may improve prediction of older men at risk of head/chest, upper extremity and hip fractures.
REMARK ON PION SCATTERING LENGTHS
Authors: BLACK DEIRDRE , FARIBORZ AMIR H. , JORA RENATA , PARK NAE WOONG , SCHECHTER JOSEPH , SHAHID M. NAEEM
Published: October 2009

First it is shown that the tree amplitude for pion–pion scattering in the minimal linear sigma model has an exact expression which is proportional to a geometric series in the quantity [Formula: see text], where mB is the sigma mass which appears in the Lagrangian and is the only a priori unknown parameter in the model. This induces an infinite series for every predicted scattering length in which each term corresponds to a given order in the chiral perturbation theory counting. It is noted that, perhaps surprisingly, the pattern, though not the exact values, of chiral perturbation theory predictions for both the isotopic spin 0 and isotopic spin 2 s-wave pion–pion scattering lengths to orders p2, p4 and p6 seems to agree with this induced pattern. The values of the p8 terms are also given for comparison with a possible future chiral perturbation theory calculation. Further aspects of this approach and future directions are briefly discussed.
EFFECTS OF REFLECTIVE SCATTERING IN NUCLEAR COLLISIONS
Authors: TROSHIN S. M. , TYURIN N. E.
Published: October 2009

We discuss effects of reflective scattering for heavy nuclei collisions and the deconfined matter formation at the LHC and asymptotical energies. Reflective scattering in hadron collisions leads to decreasing matter density with energy beyond the LHC energies. Limiting form of energy dependence of hadron density is obtained.
NEW INTEGRABLE LATTICE HIERARCHY AND ITS INTEGRABLE COUPLING
Authors: LI ZHU , DONG HUANHE
Published: October 2009

New hierarchy of Liouville integrable lattice equation and their Hamiltonian structure are generated by use of the Tu model. Then, integrable couplings of the obtained system is worked out by the extending spectral problem.
TRACKING PHASE SYNCHRONIZATION OF TWO COUPLED RÖSSLER OSCILLATORS WITH INTERNAL RESONANCE
Authors: LIU YONG
Published: October 2009

Phase synchronization between linearly and nonlinearly coupled systems with internal resonance is investigated in this paper. By introducing the conception of phase for a chaotic motion, we tune the linear coupling parameter to obtain the two Rössler oscillators in a synchronized regime and analyze the effect of a nonlinear coupling on the phase synchronized state. It demonstrates that the detuning parameter σ between the two natural frequencies ω1and ω2affects phase dynamics, and with the increase of the nonlinear coupling strength, for the primary resonance, the effect of phase synchronization between two sub-systems was decayed, while increasing with frequency ratio 1:2. Further investigation reveals that the transition of phase states between the two oscillators are related to the critical changes of the nonlinear coupling strength.
QUANTUM KEY DISTRIBUTION WITH SEVERAL INTERCEPTS AND RESEND ATTACKS
Authors: EZ-ZAHRAOUY HAMID , BENYOUSSEF ABDELILAH
Published: October 2009

The effect of several eavesdroppers intercept-resend attacks on the quantum error and mutual information between honest parties of a quantum channel chain is investigated within the BB84 (Bennett and Brassard, 1984). The quantum error and the mutual information are computed for arbitrary number of attacks. It is found that the quantum error and the secured–no secured transition depend strongly on the number N of eavesdroppers and their probabilities of intercepting attacks. For N = 3, numerical calculations show that the quantum error exhibits three kinds of different behaviors as a function of the probability of attack ω1of the first eavesdropper namely: (i) the quantum error remains constant for sufficiently small ω1, (ii) exhibits a plateau for intermediate values of ω1, (iii) increases, passes through a maximum and decreases when increasing ω1. However, depending on the probabilities of attack, phase diagrams present several kinds of topologies, in good agreement with the quantum error behavior. Moreover, in the particular case where all eavesdroppers intercept with identical probabilities ω, the quantum error increases as a nonlinear function with the number of eavesdroppers before reaching an upper limit of ≈ 0.475 for sufficiently large N. Besides, it is shown that the secured–no secured transition occurs under the effect of the number of eavesdroppers.
TEMPERATURE EFFECT ON VIBRATIONAL PROPERTIES OF La0.7Sr0.3MnO3
Authors: TALATI MINA , JHA PRAFULLA K.
Published: October 2009

Temperature dependence of phonons spectra and allied properties of rhombohedral La 0.7 Sr 0.3 MnO 3 are investigated by using the lattice dynamical method. A tendency of phonon mode to instability causing JT lattice distortion is reflected in a softening of the stretching mode in the phonon dispersion curve of La 0.7 Sr 0.3 MnO 3 at both 1.6 and 300 K. While the A1g mode softens because of gradual decrease in MnO 6 rotations, the stretching mode hardens upon reduction in temperature. The distinct features of phonon modes at different temperatures are also reflected in the calculated phonon density of states. Other thermal properties such as specific heat, the Debye temperature, and Grüneisen parameter are also presented. The decrease in the Debye temperature at 300 K indicates the effect of temperature in lattice softening. Anomalously high value of the Grüneisen parameter points out the presence of anharmonic lattice modes.
NONLINEAR TRANSPORT OF 2D ELECTRONS IN CROSSED ELECTRIC AND QUANTIZING MAGNETIC FIELDS
Authors: VITKALOV SERGEY
Published: October 2009

Nonlinear resistance of highly mobile two-dimensional electrons placed in crossed electric and strong magnetic fields attracts considerable contemporary interest. The resistance shows remarkably strong and nontrivial dependence on the electric field E in both microwave and dc responses. At small electric fields, the resistance demonstrates impressive several-fold reduction with the electric field, which is unusual for degenerate electron systems. A higher electric field induces appreciable oscillations of the resistance with both electric and magnetic fields. Zero resistance and zero differential resistance states of the 2D electrons are observed in these strongly nonlinear systems. Experiments show that the nonlinearities are related to a quantization of the electron spectrum in magnetic fields. Essential progress has been achieved in the theoretical description of dominant mechanisms responsible for the strong electron nonlinearity. The review describes recent development in this interesting area.
REGULARITY RESULTS FOR THREE-DIMENSIONAL ISOTROPIC AND KINEMATIC HARDENING INCLUDING BOUNDARY DIFFERENTIABILITY
Authors: FREHSE JENS , LÖBACH DOMINIQUE
Published: October 2009

For a flat Dirichlet boundary we prove that the first normal derivatives of the stresses and internal parameters are in L∞(0, T; L1+δ) and in L∞(0, T; H½-δ) up to the boundary.

This deals with solutions of elastic–plastic flow problems with isotropic or kinematic hardening with von Mises yield function.

We show that the elastic strain tensor ε(u) of three-dimensional plasticity with isotropic hardening is contained in the space [Formula: see text] and in L∞(0,T;H4-δ) up to the flat Dirichlet boundary. We obtain related results concerning traces of ε(u). In the case of kinematic hardening we present a simple proof of the [Formula: see text] inclusion of the elastic strain tensor.
Red Emission Properties of YNbO4:Eu3+ Phosphors Under Near UV Excitation
Authors: Lee Eun Young , Kim Young Jin
Published: October 2009

YNbO4:Eu3+ powders were prepared by a flux method, and then red emission properties under near ultraviolet (397 nm) excitation were investigated. The effects of the temperature, the LiCl content, and the Eu3+ concentration on luminescent properties were characterized.
Reductive Intramolecular Cyclization of D-Glucose-Based Unsaturated Substrates by Indirect Electrochemical Approach in "Green" Media
Authors: Dias T.A. , Durães C. , Esteves A.P. , Medeiros Maria J. , Pletcher D.
Published: October 2009

Radical cyclisation continues to be a central methodology for the preparation of natural products containing heterocyclic rings. Hence, some electrochemical results obtained by cyclic voltammetry and controlled-potential electrolysis in the study of electroreductive intramolecular cyclisation of ethyl (2S, 3R)-2-bromo-3-propargyloxy-3-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopy-ranosiloxy) propanoate (1) promoted by (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetra-decane)nickel(I), [Ni(tmc)]+, electrogenerated at glassy carbon cathodes in ethanol and ethanol/water mixtures containing tetraalkylammonium salts, are presented. During controlled-potential electrolyses of solutions containing [Ni(tmc)]2+ and acetylated D-glucose-based bromo propargyl ester (1) catalytic reduction of the latter proceeds via one-electron cleavage of the carbon-bromine bond to form a radical intermediate that undergoes cyclization to afford the substituted tetrahydrofurans.
Electrochemical Studies of the Fries Rearrangement
Authors: Cheek Graham T.
Published: October 2009

The Fries rearrangement of phenyl benzoate in acetonitrile / tetraethylammonium perchlorate has been investigated using Hf(TfO)4 as the Lewis acid. Instead of the usual 2-hydroxy- and 4-hydroxybenzophenone products, 9-fluorenone is formed in this system. The formation of 9-fluorenone is attributed to the initial formation of 2-hydroxybenzophenone, followed by an intramolecular cyclization to form 9-fluorenone.
Synthesis of ZnO@CNTs From Anhydrous Zinc Acetate via Thermal Decomposition
Authors: Chen Jingxing , Xia Nannan , Tan Sanxiang , Zhou Tianxiang , Yuan Dingsheng
Published: October 2009

The ZnO@CNTs has been prepared via a thermal decomposition route. The spectra of X-ray powder diffraction (XRD) prove that as-prepared ZnO is primitive hexagonal phase and CNTs with an interlayer distance of 0.34 nm is low graphitized carbon in this research. The diameter and length of ZnO@CNTs are 150-200nm and 1.5-2μm, respectively. The vibration on 1625cm-1, 1540cm-1 and 1380 cm-1 shows that the surface of ZnO@CNTs have great functional groups.
Local Structure of Nanocrystalline Diamond - Evolution with Thermal Treatments
Authors: Ballutaud Dominique , Pinault Marie-Amandine , Lusson Alain , Vigneron Jacky , Saada Samuel
Published: October 2009

The modifications of the sp2 carbon phases in CVD nanocrystalline diamond with 25 nm grain size are analysed by ultra-violet source Raman spectroscopy, Fourier transformed infra-red spectroscopy (FTIR) and and X-ray photoelectron spectroscopy (XPS), according to different thermal annealing treatments. Hydrogen concentration is measured by secondary ion mass spectrometry. The hydrogen outdiffusion of the sample as a function of temperature is recorded by mass spectrometry. The Raman spectra show evolution of the signal of the two G and D bands at 1360 and 1530 cm-1 related to more or less disordered sp2 phases, and of the 1150 cm-1 peak attributed to acetylenic chains located at grain boundaries. Thermal annealing breaks the short distance order in sp2 phases. FTIR and XPS analysis show that the sp2 CHx bonds are the less stable and that the superficial sp3 diamond carbon bonds recover as a result of the hydrogen departure.
Graphene-Nanotube Ribbon Structures: Architecture, Electronic Properties and Applications
Authors: Chernozatonskii Leonid A. , Sorokin Pavel
Published: October 2009

The new crystal composites consisted of two excited materials - nanotubes and graphene nanoribbons - have been investigated. The electronic structures of such covalent-bonded systems are studied in details.
Carbon Nanotube-based, Membrane-less and Mediator-free Enzymatic Biofuel Cells
Authors: Wang Shiunchin , Patlolla Anitha , Iqbal Zafar
Published: October 2009

A direct electron transfer single wall carbon nanotube (SWNT)- based biofuel cell on a gold-coated porous silicon (pSi) substrate shows a peak power density of 12 microwatts/cm2 in 4 mM glucose (corresponding to normal blood sugar concentration) with an average power of 1 microwatt over 48 hours of operation. An interesting feature of this biofuel cell is that it can be re-activated to operate with an average power output of 1 microwatt/cm2 after storage for 3 months at 4 C. Gold particles were electrolessly self-assembled on each pSi substrate from HAuCl4 solution in alcohol after similarly depositing an adhesion-promoting Cr layer. The hierarchy of pores on pSi enables nanoscale transport during fuel cell operation via capillary and wicking effects. Carboxylated SWNTs were deposited by an electrophoretic process, followed by electrochemically-induced covalent immobilization of anodic glucose oxidase and cathodic laccase enzymes on the nanotubes to form the biofuel cell structure.
Solid Oxide Membrane Electrolyzer Utilizing the Energy Value in Solid and Gaseous Reductant for Hydrogen Production
Authors: Pati Soobhankar , Yoon Kyung Joong , Chin Justin , Gopalan Srikanth , Pal Uday
Published: October 2009

This paper describes a novel Solid Oxide Membrane (SOM) electrolyzer that can utilize the energy value in any carbon and hydrocarbon reductant to lower the energy requirement for hydrogen production from steam. The Solid Oxide Membrane (SOM) electrolyzer consists of a one-end closed oxygen-ion conducting yttria stabilized zirconia (YSZ) tube with Ni-YSZ cathode coated on the outside and liquid metal anode inside the tube. In the SOM electrolyzer steam is reduced at the cathode and the oxygen produced on the anodic side reacts with the reductant supplied in the liquid metal anode. In the present study the SOM electrolyzer is evaluated using solid carbon and humidified hydrogen as reductant.
Materials Challenges in Hydrogen Production from Hydrocarbons
Authors: Chun Charlie , Hershkowitz Frank , Ramanarayanan Trikur
Published: October 2009

Currently, about 80 pct. of hydrogen is produced from natural gas alone by Steam Methane Reforming (SMR), Partial Oxidation (POX) and Autothermal Reforming (ATR) in the form of syngas which is mainly a mixture of hydrogen and carbon monoxide. Produced hydrogen is predominantly used to manufacture basic chemicals such as ammonia and methanol and to upgrade petroleum products and oils in refining processes. There are many corrosion related materials challenges in industrial processes for syngas production from fossil fuels. This paper examines these challenges with particular emphasis on a high temperature material degradation phenomenon termed "metal dusting". Control strategies to combat this form of corrosion are also outlined. Also included are materials challenges related to ExxonMobil's advanced steam reforming process known as Pressure Swing Reforming (PSR). This technology is a new way to make syngas from gaseous as well as liquid hydrocarbons and can be utilized in different process scenarios ranging from on-board vehicle reforming to industrial syngas production.
Preparation and Hydrogen Storage Performance of Pd Nanoparticles Decorated Carbon Nanotubes
Authors: Chang Jeng-Kuei , Chen Chih-Yao , Tsai Wen-Ta
Published: October 2009

Supercritical carbon dioxide (scCO2) fluid is used to decorate multi-walled carbon nanotubes (CNTs) with palladium (Pd) nanoparticles. Pd(II) hexafluoroacetylacetonate (Pd(hfa)2) is dissolved in scCO2 as a metal precursor. Electrochemical reduction of the Pd(II) is executed by dimethyl amineborane (DMAB). Owing to the high diffusivity, near-zero surface tension, and low viscosity of the scCO2 fluid, the deposited Pd nanoparticles are uniformly dispersed and tightly anchored on the surface of CNTs. The microstructure, chemical composition, and crystallinity of the prepared Pd/CNTs nano-composites are characterized with a transmission electron microscope (TEM), an X-ray energy dispersive spectroscope (EDS), and an X-ray diffractometer (XRD), respectively. The experimental results indicate that the size and the amount of Pd particles on CNTs can be manipulated by adjusting the precursor concentration. Moreover, hydrogen storage capability of the Pd/CNTs composite, evaluated with a high-pressure microbalance (at 6.89 MPa and 25{degree sign}C), is 1.31 wt %, which is approximately four times higher than that (0.33 wt%) of pristine CNTs.
Time Dependent Analysis of a Metal Hydride Bed
Authors: Song Ke , Knickle Harold N.
Published: October 2009

In this paper we present a study of the time dependent analysis of a metal hydride bed (MHB) which provides constant flow to a fuel cell at required power loading and pressure. The hydrogen gas phase pressure, the hydrogen concentration in the metal hydride and the hydrogen desorption rate are consider as key variables in this study. Both the space scale and time scale analysis are performed. Parameters investigations are also conducted. All the simulations are treated at isothermal conditions and applied using COMSOL software.
Effect of SO2 Crossover on Hydrogen and Sulfuric Acid Production in a PEM Electrolyzer
Authors: Staser John A. , Weidner J. W.
Published: October 2009

The hybrid sulfur process has been investigated as a means to produce clean hydrogen from renewable sources. A gas-phase electrolyzer has been developed in which SO2 is fed to the anode and oxidized in the presence of water to from H2SO4 with the co-production of H2 at the cathode. We have demonstrated successful operation of this electrolyzer, and have investigated the effects of water management on electrolyzer performance. Here, we extend our investigation of water management to its effect of SO2 crossover.
Nickel Based Anodes of Single Chamber Solid Oxide Fuel Cells: A Catalytic Study
Authors: Gadacz Geoffroy , Udroiu Sorina , Viricelle Jean-Paul , Pijolat Christophe , Pijolat Michèle
Published: October 2009

Single chamber solid oxide fuel cells (SCFC) are an alternative concept to traditional SOFC's. Conventional anodes, which consist of a cermet of metallic Ni and ionic conductor, have to work under a mixture of hydrocarbon and oxygen. This paper presents a catalytic study of C3H8 oxidation by Ce0.9Gd0.1O1.95 and nickel. The influence of temperature and oxygen to propane ratio on the nickel oxidation state are clarified thanks to catalytic tests and electrical conductivity measurements. The results show that the temperature must be higher than a critical value in order to maintain the nickel particles in the metallic state. Furthermore, at high temperature, the conversion of the initial mixture leads to the water-gas-shift equilibrium.
Effect of Nitrogen Concentration on Nanodiamond Film Characteristics for Electrode Application
Authors: Raina Supil , LeQuan Xuan-Anh C. , Kang Weng P. , Davidson J. L.
Published: October 2009

Microwave plasma chemical vapor deposition was used to fabricate nanodiamond films. Nitrogen incorporation was achieved by the introduction of N2 gas along with H2 and CH4 gases in the plasma. SEM studies revealed a change in the microstructure with increase in the N2 flow rate, transitioning from a 'ridge'-like surface morphology to a more 'cauliflower'-like structure. X-ray photoelectron spectroscopy (XPS) analysis showed a general decrease in the sp3 hybridized carbon content while the sp2 hybridized carbon content increased with N2 flow rate (up to 28.7%) after which it declines. Deconvolution of the C1s XPS spectra indicates incorporation of nitrogen and existence of carbon-nitrogen bonding. Raman spectroscopy shows diamond peak at 1332 cm-1 and the graphite peak, which increases in intensity and shifts towards lower wave number with increase in the N2 flow rate. A diffuse band at 1140 cm-1 indicates presence of a nanocrystalline phase in the films.
Electrochemical-Thermal Modeling of Spirally Wound Batteries
Authors: Gomadam Parthasarathy , White Ralph E. , Weidner J. W.
Published: October 2009

This paper demonstrates the application of the coordinate-transformation approach developed elsewhere (Gomadam et al. J. Electrochem. Soc.. 150, A1339, 2003) in electrochemical-thermal modeling of spirally wound batteries. The approach presented here allows for easy adaptation of a two-dimensional electrochemical-thermal model of a plate-type cell (ie. a single rectangular anode-cathode couple) to a spirally-wound battery. Model predictions are presented and analyzed for situations when spiral heat conduction is important.
On the Origin of the Imaginary Part of the Ohmic Impedance
Authors: Blanc Christine , Orazem M. E. , Pébère Nadine , Tribollet Bernard , Vivier Vincent
Published: October 2009

The local and global Ohmic response for an electrode exhibiting geometry-induced potential and/or current distributions has recently been shown to be represented by a frequency-dependent complex impedance. A physical explanation for this result is provided in terms of the radial contribution to local current density and the decrease in current density along the current lines.
Synthesis, Characterization and Application of Nanostructured Porous Metal Oxides
Authors: Liu Qiang , Chen Frank , Song Weiguo
Published: October 2009

Porous nanostructured materials have attracted much attention recently due to their potential application in the field of catalysis, sensing and adsorptions. General ways for the preparation of meso- and macro- porous structured single/mixed metal oxides have been developed in this work, including hydrothermal method to synthesize mesoporous transition metal oxides (TMOs) and self-rising approach to obtain macroporous TMOs.
The Silica-Coated Gold Nanoparticles Encapsulation of Plastic Polymer Light- Emitting Devices
Authors: Chiu Pin-Hsiang , Chen Kan-Lin , Huang Chien-Jung , Tsai Jenn-Kai , Yang Cheng-Fu , Wang Yeong-Her
Published: October 2009

Polymer light-emitting devices (PLEDs) are extremely sensitive to moisture and oxygen. Without high-performance hermetic encapsulations, the life of these devices is limited. This paper reports the lifetime characteristics of plastic PLED containing a hermetic multi-layer encapsulation by configuration of silicon dioxide (SiO2)/ silica-coated gold nanoparticles /SiO2 layer. The electroluminescent (EL) features were examined to compare the rate of degradation in the devices with the multi-layer encapsulation and the SiO2 single-layer encapsulation. Thus, it is confirmed that the multi-layer encapsulation with passivation layer of silica-coated gold nanoparticles has an effect as encapsulation process to protect plastic PLED.
Luminescence of ZnS:Cu,Cl Phosphor Powder Excited by Photons, an Electric Field and Cathode Rays
Authors: Nien Yung-Tang , Chen In-Gann
Published: October 2009

ZnS:Cu,Cl phosphor powder prepared by a solid state reaction at 900oC showed a broad emission peak in 400- 600nm, consisting of blue (440nm), self-activated (470nm) and green (510nm) bands. The emission color of the phosphor powder, originating from the relative intensity of these three bands, was found to depend on the excitation method, i.e., bluish green by photons, greenish blue under an electric field, and blue by cathode rays. This behavior was thought to result from the different penetration depth of excitation energy as well as from the spatial distribution of activators in the phosphor.
Identification and Validation of Analytical Chemistry Methods for Detecting Composite Surface Contamination and Moisture - Solid-State Electrochemical Sensor Study
Authors: Zhou Xiangyang , Zhou Juanjuan , Wang Zedong , McDaniel Dwayne , Zhang Weihua , Burton Richard
Published: October 2009

In-field surface contamination and moisture detection is one of the critical issues in preparation of adhesive bonds between composite adherends for aircraft manufacture. In this paper, the feasibility of an all solid-sate electrochemical sensor technology is explored. Redox pairs or mediators are combined into a solid-state electrolyte, NafionTM. The output current in response to a cyclic polarization is used as the indication of the surface contamination level. Electrochemical impedance spectroscopy measurements using the sensors made were conducted. The results indicate that the small amount of moisture and/or sulfuric acid on initially cleaned and vacuumed polymer surfaces results in about 10 times increment of the peak current in cyclic voltammetry tests.
Surface Potential Changes Induced by Physisorption of Si-tagged Protein A on HF-last Si(100) and Thermally Grown SiO2 surfaces
Authors: Mahboob Syed , Makihara Katsunori , Ohta Akio , Higashi Seiichiro , Hata Yumehiro , Kuroda Akio , Miyazaki Seiichi
Published: October 2009

We successfully detected Si-tagged protein A, attached to OH-terminated SiO2 and H-terminated Si surfaces by surface potential measurements using an AFM/Kelvin probe technique. Significant change in topographic images were observed after scratching the surface by contact mode AFM measurements indicating formation of multilayer film for Si-tagged protein A solution with concentration 100mg/l. The surface potential increased by a factor of 3 and 5 for OH-terminated SiO2 and H-terminated Si surfaces after the attachment of the Si-tagged protein A. We also observed significant change in surface potential after attachment of Si-tagged protein A with different pH. The surface potential increased with the increase of the pH of the Si-tagged protein A solution. It is suggested that pH of the biosolution is important to effectively physisorb the Si-tagged protein A. These results will open up the fabrication of a sensing device for locally ionized biomolecules.
From Metals to Semiconductors: Challenges in Electrodeposition for Photovoltaic Applications
Authors: Chassaing Elisabeth , Guillemoles Jean-François , Lincot Daniel
Published: October 2009

This paper presents a general view of the electrodeposition of semiconductors, focusing on chalcogenides (CdTe, Cu(In,Ga)(Se,S)2 and oxides (ZnO), which are under intense development for photovoltaic applications. It recalls the basic interfacial mechanisms involved in the electrodeposition steps of semiconductors, which control the quality and structure of the layers.
Interfacial Structure and Chemistry of Potentiodynamically Electrodeposited Ultrathin Pd Films on Pt(111)
Authors: Park Yeon-Su , Baricuatro Jack H. , Hossain Mohammad A. , Soriaga Manuel P.
Published: October 2009

Ultrathin Pd films, with coverages from 0.5 monolayers (ML) to 8 ML, were prepared by potential-sweep deposition on well defined Pt(111) surfaces. Analysis of the voltammetric peaks characteristic of hydrogen adsorption/desorption on Pd terrace and step sites revealed that, 1 ML coverage, the film remained step-free but, at higher coverages, formed 3D islands (Stranski-Krastanov growth mode). Corroborating evidences were provided by low-energy electron diffraction and Auger electron spectroscopy.
Understanding, Controlling and Minimizing the Voiding, Sporadically Occurring in Solder Joints with Electroplated Copper
Authors: Wafula Fred , Liu Yihua , Yin Liang , Bliznakov Stoyan , Borgesen Peter , Cotts Eric , Dimitrov Nikolay
Published: October 2009

The lifetime of solder joints with electrodeposited Cu has been an issue to date as many electronic devices have shown a high drop impact failure as a result of a sporadic void formation in the intermetallic compound (IMC). At present, this problem aggravates with the introduction of Pb-free solders. It was recently found that incorporated impurities promote the voiding propensity of Cu/solder joints. The aim of this work is to quantitatively study the role of key Cu plating parameters in the impurity incorporation process. Technically emphasized herein is the plating temperature. Combining results of this study and pre-existing data, a correlation between plating rate, temperature, overpotential, and voiding propensity of accordingly deposited Cu layers is established. Ranges of overpotentials where either "void prone" or "void-free" Cu could be deposited are clearly identified in two separate acidic Cu plating solutions containing different additive combinations. The proposed analysis enables the prediction and control of the voiding propensity of solder joints with electrodeposited Cu layers.
Future Technology Proposal for Damascene Process Using All Wet Electrochemical Technique
Authors: Osaka Tetsuya , Yoshino Masahiro , Shacham-Diamand Yosi
Published: October 2009

All-wet process was developed for fabricating diffusion barrier layer and Copper wiring for ultra large scale integration (ULSI) by means of a combination technique of electroless deposition and surface modification of Pd-activated ligand-bearing organic layer. In this paper, we performed detailed analysis of the Pd-activated ligand-bearing organic layer. Moreover, we successfully deposited thin electroless NiB layer on the Pd-activated molecular layer of 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS) in a small reactor at a low temperature in a few minutes.
Automated Electrodeposition of Bimetallic Noble-Metal Nanoclusters via Redox-Replacement Reactions for Electrocatalysis
Authors: Mkwizu Tumaini S. , Mathe Mkhulu , Cukrowski Ignacy
Published: October 2009

Nanoclusters of bimetallic composition involving platinum with gold or ruthenium were sequentially deposited via redox-replacement of electrodeposited sacrificial Cu adlayers for controlling the deposition of the noble metals. These steps were repeated for a desired number of automated cycles toward: (a) stepwise increase of the size of nanostructures, and (b) stepwise synthesis of the nanostructures in relation to tuning of their electrocatalytic properties. Studies were also performed by eliminating the Cu replacement steps (direct spontaneous deposition) as well as implementing sequential codeposition of the noble-metals with simultaneous Cu redox-replacement steps. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were implemented to characterize properties of the bimetallic nanoclusters with respect to morphology, elemental composition, and electrocatalytic activity for methanol oxidation. The order of electrocatalytic activity for methanol oxidation in acidic medium was (Ru│Pt) > (Au│Pt) > Pt in line with the bifunctional mechanism.
Automotive Traction Battery Needs and the Influence of Mechanical Degradation of Insertion-electrode Particles
Authors: Verbrugge Mark , Cheng Yang-Tse
Published: October 2009

We derive and implement analytic solutions for the description of insertion particles subject to cyclic surface concentration variations consistent with a periodic voltage excitation source applied to an insertion electrode wherein the overall resistance is dominated by that of solid-state diffusion within the electrode particles. The form of the analytic solution allows for a direct analogy to cyclic fatigue phenomena that have been examined in detail for structural materials over the past two centuries. We utilize the strain energy density to assess the potential for crack nucleation, and we show that while the shear stress is independent of the surface tension and surface modulus, the strain energy density, which drives particle fracture, is sensitive to the surface mechanics and therefore the particle radii. Specifically, the analysis implies that smaller particles are more stable relative to diffusion-induced decrepitation and cracking, consistent with experimental observations.
Infiltrated Electrodes for Intermediate-Temperature Solid Oxide Fuel Cells
Authors: Zhao Fei , Chen Frank , Xia ChangRong
Published: October 2009

Solid oxide fuel cells (SOFCs) are among the most promising devices for environmentally clean electricity generation using different fuels such as hydrogen and hydrocarbons. In order to improve the performance and durability of intermediate-temperature SOFCs, novel infiltration approach has been applied to fabricate anode capable of direct oxidation of hydrocarbon fuels and cathode with high performance and improved stability.
Oxygen Reduction Reaction of Partially Oxidized Tantalum Carbonitride as Non-Platinum Cathode for PEFC: Dependence of Degree of Oxidation of Tantalum Carbonitride on Catalytic Activity
Authors: Ota Ken-ichiro , Imai Hideto , Matsuzawa Koichi , Mitsushima Shigenori , Ishihara Akimitsu
Published: October 2009

A partially oxidized TaC0.58N0.42 has been investigated as a new cathode for polymer electrolyte fuel cells. The catalytic activity for oxygen reduction reaction significantly depended on a degree of oxidation of the TaC0.58N0.42. The onset potential on the partially oxidized TaC0.58N0.42 for the ORR had a maximum value of 0.9 V vs. RHE in 0.1 mol dm-3 H2SO4 at 30oC. The partially oxidized TaC0.58N0.42 powders were characterized by transmission electron microscopy observation observation, X-ray absorption spectroscopy, and average composition.
A Mathematical Model for the Inductance Observed in the Impedance Spectrum of Corroding Aluminium
Authors: Mann Rudi , Nauer Gerhard
Published: October 2009

In the course of evaluating data of impedance spectra of aluminum samples, the interpretation and mathematical formulation of the inductive part at low frequencies of the applied alternating voltage is still unclear. In this work, based on the assumption of a breakdown and re-building of the passive layer on the aluminum substrate, a mathematical model was developed for the interpretation of these inductive loops.
Dynamic Electrochemical Impedance Spectroscopy
Authors: Sacci Robert L. , Harrington David
Published: October 2009

The hardware and software for a dynamic electrochemical impedance spectroscopy system are described. The applied waveform is a continuous computer-generated multisine waveform added to a potential sweep. A fast potentiostat applies the potential signal and the impedance is derived from the Fourier transforms of the measured current and potential responses. Impedance spectra are available continuously around the cyclic voltammogram. The quality and limitations of the system are investigated with several dummy cells
Impedance Spectroscopy of Platinum in Sulfuric Acid Under Cathodic and Anodic Polarization
Authors: Baranova Elena , Kuznetsov Oleksandr O.
Published: October 2009

Impedance of polycrystalline platinum interfaced with 0.5 M H2SO4 in the broad range of electrode potentials was investigated. For the interpretation of the experimental data, statistical criteria linking the real and the imaginary parts of the impedance were employed. After analysis of the experimental data it was found that the impedance of Pt throughout the potential region between -0.16 and 1.54 V (RHE) may be modeled by the equivalent circuit that includes in addition to the set of resistors and capacitors, the frequency-dependent element corresponding to the Warburg impedance.
Novel Plating Cell Geometry for Uniform Metal Distribution
Authors: Garich Holly , Gebhart Larry , Snyder Stephen , Taylor E. Jennings
Published: October 2009

Faraday Technology, Inc. has developed a number of novel processing cells based on an innovative cell geometry that results in high levels of processing uniformity. This geometry is comprised of a number of unique attributes for the uniform electrodeposition or electroetching of metals across large planar substrates as well as fine features that are utilized for printed circuit board (PCB) and electronic packaging applications. The cell has been characterized with a 457 mm x 610 mm substrate. A coefficient of variation of 5.3% was achieved in FARADAYIC® ElectroCell over a 457 mm x 610 mm substrate; these values were compared to a commercial system. This cell design has been applied to a number of industrial processes, including electroplating of copper, trivalent chromium and platinum and electroetching of copper for interlayer circuit board applications. The current work outlines the importance of various cell components and resulting uniformity.
Through Mask Electrochemical Machining
Authors: McCrabb Heather , Lozano-Morales Alonso , Snyder Stephen , Gebhart Larry , Taylor E. Jennings
Published: October 2009

A pulse and pulse reverse through mask electrochemical machining (ECM) process is being developed for fabrication of gas flow field channels on metal bipolar plates used in PEM fuel cells. The process involves patterning a photoresist mask on the surface of the bipolar plate to protect specific areas during the ECM process. A pulsed electric field is applied between the bipolar plate and a suitable counter electrode to remove the metal not protected by the photoresist mask. The application of pulsed electric fields, as opposed to constant direct current (DC) electric fields provides an improved level of control through optimization of the pulse parameters. The influence of the through mask pulse and pulse reverse ECM processing parameters, such as electrolyte composition, flow rates, pulsed voltage, pulsed on-times and off-times on material removal rates, surface finish, accuracy and dimensional control for the channel fabrication are examined.