bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between individual characteristics, neighbourhood contexts and help-seeking intentions for mental illness
Authors: Suka Machi , Yamauchi Takashi , Sugimori Hiroki
Published: August 2015

Objective

Encouraging help-seeking for mental illness is essential for prevention of suicide. This study examined the relationship between individual characteristics, neighbourhood contexts and help-seeking intentions for mental illness for the purpose of elucidating the role of neighbourhood in the help-seeking process.

Design, setting and participants

A cross-sectional web-based survey was conducted among Japanese adults aged 20–59 years in June 2014. Eligible respondents who did not have a serious health condition were included in this study (n=3308).

Main outcome measures

Participants were asked how likely they would be to seek help from someone close to them (informal help) and medical professionals (formal help), respectively, if they were suffering from serious mental illness. Path analysis with structural equation modelling was performed to represent plausible connections between individual characteristics, neighbourhood contexts, and informal and formal help-seeking intentions.

Results

The acceptable fitting model indicated that those who had a tendency to consult about everyday affairs were significantly more likely to express an informal help-seeking intention that was directly associated with a formal help-seeking intention. Those living in a communicative neighbourhood, where neighbours say hello whenever they pass each other, were significantly more likely to express informal and formal help-seeking intentions. Those living in a supportive neighbourhood, where neighbours work together to solve neighbourhood problems, were significantly more likely to express an informal help-seeking intention. Adequate health literacy was directly associated with informal and formal help-seeking intentions, along with having an indirect effect on the formal help-seeking intention through developed positive perception of professional help.

Conclusions

The results of this study bear out the hypothesis that neighbourhood context contributes to help-seeking intentions for mental illness. Living in a neighbourhood with a communicative atmosphere and having adequate health literacy were acknowledged as possible facilitating factors for informal and formal help-seeking for mental illness.
Millennials at work: workplace environments of young adults and associations with weight-related health
Authors: Watts Allison W , Laska Melissa N , Larson Nicole I , Neumark-Sztainer Dianne R
Published: August 2015

Background

The purpose of this study was to describe the workplace environments of young adults and examine associations with diet, physical activity (PA) and body mass index (BMI).

Methods

Cross-sectional data were collected (2008–2009) from 1538 employed young adult participants in Project EAT (Eating and Activity among Teens and Young Adults), a diverse population-based sample. Survey measures assessed height, weight, diet, moderate-to-vigorous PA, transportation-related PA and perceptions of the workplace food and PA environments (eg, soda availability, coworker support). Healthful characteristics were summed to reflect overall workplace healthfulness. Modified Poisson regression analyses conducted in 2015 identified associations between workplace food and PA environments and diet, PA and BMI.

Results

The healthfulness of workplace environments was suboptimal. Greater exposure to healthful workplace characteristics was related to more young adults engaged in favourable diet and PA behaviours and a lower prevalence obesity. For example, adjusted rates of obesity were 24% and 17% among those reporting low (≤1 characteristic) versus high (≥3 characteristics) exposure to healthful food environments, respectively (p<0.05). Workplace characteristics independently associated with weight-related outcomes included soda availability, proximity to a fast food outlet, living close to work and perceived ease of eating a healthy diet or being active at work.

Conclusions

A more healthful workplace environment overall, including physical attributes and perceived social norms, may contribute to more favourable weight-related behaviours and lower prevalence of obesity among young adults. Employer-initiated and community-initiated policies may represent one way to create healthier workplace environments for young adults.
Digoxin: its role in contemporary medicine
Authors: Stucky Marcelle A , Goldberger Zachary D
Published: August 2015

Digoxin has been a key therapeutic for heart failure and atrial tachyarrhythmias for over 200 years following Withering's groundbreaking work depicting the therapeutic benefit of the common botanical foxglove in his 1785 monograph. The use of digoxin preceded any randomised evidence or even basic understanding of its mechanism of action. Over the past two decades, there has been mounting evidence further challenging the safety and efficacy of digoxin, while multiple other therapies for both heart failure and atrial tachyarrhythmias have proven to be more effective and safe. Altogether, digoxin still has an important role in contemporary pharmacotherapeutics, though its role remains controversial and should be reserved for selective patients and clinical situations, with careful attention to serum concentrations.
(μ, ν)-Pseudo almost automorphic solutions for some non-autonomous differential equations
Authors: Ait Dads El Hadi , Ezzinbi Khalil , Miraoui Mohsen
Published: August 2015

The aim of this work is to study the new concept of the (μ, ν)-pseudo almost automorphic functions for some non-autonomous differential equations. We suppose that the linear part has an exponential dichotomy. The nonlinear part is assumed to be (μ, ν)-pseudo almost automorphic. We show some results regarding the completness and the invariance of the space consisting in (μ, ν)-pseudo almost automorphic functions. Then we propose to study the existence of (μ, ν)-pseudo almost automorphic solutions for some differential equations involving reflection of the argument.
Closure operators on algebras
Authors: Pilitowska Agata , Zamojska-Dzienio Anna
Published: August 2015

We study connections between closure operators on an algebra (A, Ω) and congruences on the extended power algebra defined on the same algebra. We use these connections to give an alternative description of the lattice of all subvarieties of semilattice ordered algebras.
IDENTIFICATION OF ABNORMAL PHASE AND ITS FORMATION MECHANISM IN SYNTHESIZING CHALCOGENIDE FILMS
Authors: LIU KEGAO , JI NIANJING , XU YONG , LIU HONG
Published: August 2015

Chalcogenide films can be used in thin-film solar cells due to their high photoelectric conversion efficiencies. It was difficult to identify one abnormal phase with high X-ray diffraction (XRD) intensity and preferred orientation in the samples for preparing chalcogenide films by spin-coating and co-reduction on soda-lime glass ([Formula: see text]) substrates. The raw materials and reductant are metal chlorides and hydrazine hydrate respectively. In order to identify this phase, a series of experiments were done under different conditions. The phases of obtained products were analyzed by XRD and the size and morphology were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). From the experimental results, first it was proved that the abnormal phase was water-soluble by water immersion experiment, then it was identified as NaCl crystal through XRD, energy dispersive spectrometer (EDS) and SEM. The cubic NaCl crystals have high crystallinity with size lengths of about 0.5–2[Formula: see text][Formula: see text]m and show a [Formula: see text]100[Formula: see text] preferred orientation. The reaction mechanism of NaCl crystal was proposed as follows: The NaCl crystal was formed by reaction of Na2O and HCl in a certain experimental conditions.
Comparison Between an HVS Inspired Linear Filter and the Bilateral Filter in Performing "Vision at a Glance" through Smoothing with Edge Preservation
Authors: Bhattacharjee Debjyoti , Bakshi Ashish , Ghosh Kuntal
Published: August 2015

We propose that the Magno (M)-channel filter, belonging to the extended classical receptive field (ECRF) model, provides us with "vision at a glance", by performing smoothing with edge preservation. We compare the performance of the M-channel filter with the well-known bilateral filter in achieving such "vision at a glance" which is akin to image preprocessing in the computer vision domain. We find that at higher noise levels, the M-channel filter performs better than the bilateral filter in terms of reducing noise while preserving edge details. The M-channel filter is also significantly simpler and therefore faster than the bilateral filter. Overall, the M-channel filter enables us to model, simulate and arrive at a better understanding of some of the initial mechanisms in visual pathway, while simultaneously providing a fast, biologically inspired algorithm for digital image preprocessing.
Improving Graph-Based Image Segmentation Using Nonlinear Color Similarity Metrics
Authors: Carvalho L. E. , Mantelli Neto S. L. , Sobieranski A. C. , Comunello E. , von Wangenheim A.
Published: August 2015

We present a new segmentation method called weighted Felzenszwalb and Huttenlocher (WFH), an improved version of the well-known graph-based segmentation method, Felzenszwalb and Huttenlocher (FH). Our algorithm uses a nonlinear discrimination function based on polynomial Mahalanobis Distance (PMD) as the color similarity metric. Two empirical validation experiments were performed using as a golden standard ground truths (GTs) from a publicly available source, the Berkeley dataset, and an objective segmentation quality measure, the Rand dissimilarity index. In the first experiment the results were compared against the original FH method. In the second, WFH was compared against several well-known segmentation methods. In both cases, WFH presented significant better similarity results when compared with the golden standard and segmentation results presented a reduction of over-segmented regions.
When is a Decision-Making Method Trustworthy? Criteria for Evaluating Multi-Criteria Decision-Making Methods
Authors: Saaty Thomas L. , Ergu Daji
Published: August 2015

Decision makers often face complicated decision problems with intangible and conflicting criteria. Numerous multi-criteria decision-making (MCDM) methods have been proposed to handle the measurement of the priorities of conflicting tangible/intangible criteria and in turn use them to choose the best alternative for a decision. However, the presence of many MCDM methods bewilders users. The existence of these methods becomes a decision problem in itself, and decision makers may be uncertain about which one to use. Thus the comparative analysis and evaluation of various MCDM methods has come under scrutiny by both researchers and practitioners in order to discover if there are logical, mathematical, social or practical reasons why one method is better than another. Criteria for their evaluation are the first important issue that needs to be resolved. In this paper, 16 criteria are introduced that may be used to judge and evaluate various MCDM methods. The criteria proposed and some guidelines for their evaluation are given to help readers evaluate these MCDM methods.
Estimation of isoform expression in RNA-seq data using a hierarchical Bayesian model
Authors: Wang Zengmiao , Wang Jun , Wu Changjing , Deng Minghua
Published: August 2015

Estimation of gene or isoform expression is a fundamental step in many transcriptome analysis tasks, such as differential expression analysis, eQTL (or sQTL) studies, and biological network construction. RNA-seq technology enables us to monitor the expression on genome-wide scale at single base pair resolution and offers the possibility of accurately measuring expression at the level of isoform. However, challenges remain because of non-uniform read sampling and the presence of various biases in RNA-seq data. In this paper, we present a novel hierarchical Bayesian method to estimate isoform expression. While most of the existing methods treat gene expression as a by-product, we incorporate it into our model and explicitly describe its relationship with corresponding isoform expression using a Multinomial distribution. In this way, gene and isoform expression are included in a unified framework and it helps us achieve a better performance over other state-of-the-art algorithms for isoform expression estimation. The effectiveness of the proposed method is demonstrated using both simulated data with known ground truth and two real RNA-seq datasets from MAQC project. The codes are available at http://www.math.pku.edu.cn/teachers/dengmh/GIExp/ .
A novel Multi-Agent Ada-Boost algorithm for predicting protein structural class with the information of protein secondary structure
Authors: Fan Ming , Zheng Bin , Li Lihua
Published: August 2015

Knowledge of the structural class of a given protein is important for understanding its folding patterns. Although a lot of efforts have been made, it still remains a challenging problem for prediction of protein structural class solely from protein sequences. The feature extraction and classification of proteins are the main problems in prediction. In this research, we extended our earlier work regarding these two aspects. In protein feature extraction, we proposed a scheme by calculating the word frequency and word position from sequences of amino acid, reduced amino acid, and secondary structure. For an accurate classification of the structural class of protein, we developed a novel Multi-Agent Ada-Boost (MA-Ada) method by integrating the features of Multi-Agent system into Ada-Boost algorithm. Extensive experiments were taken to test and compare the proposed method using four benchmark datasets in low homology. The results showed classification accuracies of 88.5%, 96.0%, 88.4%, and 85.5%, respectively, which are much better compared with the existing methods. The source code and dataset are available on request.
Computational methodology for predicting the landscape of the human–microbial interactome region level influence
Authors: Coelho Edgar D. , Santiago André M. , Arrais Joel P. , Oliveira José Luís
Published: August 2015

Microbial communities thrive in close association among themselves and with the host, establishing protein–protein interactions (PPIs) with the latter, and thus being able to benefit (positively impact) or disturb (negatively impact) biological events in the host. Despite major collaborative efforts to sequence the Human microbiome, there is still a great lack of understanding their impact. We propose a computational methodology to predict the impact of microbial proteins in human biological events, taking into account the abundance of each microbial protein and its relation to all other microbial and human proteins. This alternative methodology is centered on an improved impact estimation algorithm that integrates PPIs between human and microbial proteins with Reactome pathway data. This methodology was applied to study the impact of 24 microbial phyla over different cellular events, within 10 different human microbiomes. The results obtained confirm findings already described in the literature and explore new ones. We believe the Human microbiome can no longer be ignored as not only is there enough evidence correlating microbiome alterations and disease states, but also the return to healthy states once these alterations are reversed.
Proof of some conjectures of Z.-W. Sun on the divisibility of certain double sums
Authors: Guo Victor J. W. , Liu Ji-Cai
Published: August 2015

Sun introduced three kinds of numbers: [Formula: see text] and [Formula: see text] In this paper, we mainly prove that [Formula: see text] by establishing some binomial coefficient identities, such as [Formula: see text] This confirms several recent conjectures of Sun.
Note on the Davenport constant of the multiplicative semigroup of the quotient ring 𝔽p[x] 〈f(x)〉
Authors: Wang Haoli , Zhang Lizhen , Wang Qinghong , Qu Yongke
Published: August 2015

Let [Formula: see text] be a finite commutative semigroup. The Davenport constant of [Formula: see text], denoted [Formula: see text], is defined to be the least positive integer [Formula: see text] such that every sequence [Formula: see text] of elements in [Formula: see text] of length at least [Formula: see text] contains a proper subsequence [Formula: see text] with the sum of all terms from [Formula: see text] equaling the sum of all terms from [Formula: see text]. Let [Formula: see text] be a polynomial ring in one variable over the prime field [Formula: see text], and let [Formula: see text]. In this paper, we made a study of the Davenport constant of the multiplicative semigroup of the quotient ring [Formula: see text] and proved that, for any prime [Formula: see text] and any polynomial [Formula: see text] which factors into a product of pairwise non-associate irreducible polynomials,

[Formula: see text] where [Formula: see text] denotes the multiplicative semigroup of the quotient ring [Formula: see text] and [Formula: see text] denotes the group of units of the semigroup [Formula: see text].
Investigating biological population model using exp-function method
Authors: Ul Hassan Qazi Mahmood , Mohyud-Din Syed Tauseef
Published: August 2015

This paper is the spectator of the arrangement of an efficient transformation and exp-function technique to build up generalized exact solutions of the biological population model equation. Computational work and subsequent numerical results re-identify the effectiveness of proposed algorithm. It is pragmatic that recommended plan is greatly consistent and may be comprehensive to other nonlinear differential equations of fractional order.
Synthesis and photoluminescence properties of LaPO4:Ce3+, Tb3+ nanophosphors by microwave-assisted co-precipitation method at low temperature
Authors: Dong Wei-Li , Zhang Xi-Yan , Shi Hui , Mi Xiao-Yun , Wang Neng-Li , Han Ke-Xuan
Published: August 2015

Nanosized green phosphor LaPO 4: Ce 3+, Tb 3+ has been synthesized by microwave-assisted co-precipitation method. The morphology, crystal structure and photoluminescence properties have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The lanthanum phosphate phosphors with monoclinic crystal structure and fine crystallinity and dispersibility were synthesized at 900°C for 1 h and the particle size of the phosphors is ∼ 100 nm. The strongest photoluminescence emission peak is located at 543 nm due to the (5D4→7F5) transition of Tb 3+ ion. The experimental results indicate that nanosized green phosphor 40% Ce 3+ and 20% Tb 3+ doped LaPO 4 synthesized by microwave-assisted co-precipitation method is a beneficial phosphor for high resolution display devices.
A Proactive Approach to Global Governance Is China's Historic Choice
Authors: He Yafei
Published: August 2015

As the world moves from "governance by the West" to "co-governance by both the West and East," the inherent deficiency in current global governance architecture becomes obvious to all of us. The author, through his own experiences as both a practitioner and student of global governance, has highlighted where the deficiency is and how to remedy it. By explaining China's recent moves in proposing the Chinese dream and building "one belt and one road," the author suggests that China continue on this proactive approach in dealing with global governance and offers some ideas from Chinese cultural heritage on how to reform the global governance architecture, with an emphasis on the G20, as well as on what China and the United States can do together to achieve better global governance.
The Belt and Road Initiative and China's Foreign Policy Toward Its Territorial and Boundary Disputes
Authors: Kong Lingjie
Published: August 2015

Outstanding territorial and boundary disputes both on land and at sea between China and many of its neighbors remain a most sensitive, complicated, and enduring matter in their bilateral relations. In 2013, China proposed the Belt and Road Initiative, which aims to promote connectivity and cooperation between China and the rest of the world through the land-based Silk Road Economic Belt and the oceangoing Maritime Silk Road. Under this Initiative, frontiers, land boundaries, borderlands, maritime boundaries, and the ocean enjoy unique positions. Obviously, impacts of these outstanding territorial and boundary disputes on the Initiative should not be underestimated. Meanwhile, the Initiative can facilitate cooperation between China and other disputant states on conflict management and dispute resolution. But such an effect should not be overestimated. Indeed, it can have a side effect, inducing some disputant states to take more provocative actions.
Development of Highly Durable Ni-MH Batteries through Introduction of Highly Conductive Co Compound-Coated Ni (OH) 2 Technology
Authors: Yasuoka Shigekazu , Shuichi Doi , Imoto Yuzo , Kai Takuya , Yamazaki Takeshi , Ito Takeshi , Yano Takayuki , Takeno Kazuta , Yanagawa Hirofumi
Published: August 2015

Cells using highly conductive Co compound-coated Ni(OH)2 have good recovery characteristics after being connected to resistance. As a result of our investigation, by using synchrotron X-ray analysis (XAS, XRD), we can confirm the difference between convention material and highly conductive Co compound coated Ni(OH)2 in the cell. Through X-ray absorption it has been confirmed that the valence of the Co compound layer in the cell after charge and discharge is clearly higher than in a cell with a standard CoOOH layer. A new positive material has been developed on the basis of these analyses. By optimizing the Co compound layer coating the Ni(OH)2, we have succeeded in developing a more highly durable cell. Producing cells using these technologies results in good characteristics, balanced and with excellent performance across the board
Effect of Disorder Induced by Ball Milling on the Electrochemical Performance of Catalytically Graphitized Carbon Xerogel as Anode for Lithium Ion Batteries
Authors: Gopalakrishna Karthik Mamandur , Kakunuri Manohar , Sharma Chandra Shekhar
Published: August 2015

We have synthesized resorcinol formaldehyde based carbon xerogel (RFCX) by graphitizing it at 1800 °C in the presence of a catalyst. As-synthesized RFCX was then ball milled for different duration to develop a control on its microstructure as studied in detail using scanning electron microscopy, X-ray diffraction, BET surface area and transmission electron microscopy. Structural characterization revealed that RFCX is an example of hard carbon and with the increase in milling time, there was an increase in its structural disorder further. This increase in structural disorder was then correlated to understand the electrochemical behaviour of RFCX using cyclic voltammetry and galvanostat charge/discharge measurements. RFCX sample ball milled for 4 h showed significant increase in its reversible capacity (310 mAh/g) with 99.1% coulombic efficiency after 50 cycles. Further this change in microstructure of RFCX facilitated their use at high C-rate (up to 1 C) with excellent capacity retention. This work paves the way of efficient use of RFCX as an anode material for next generation lithium ion batteries.
Sulphate Doped Polypyrrole Tin Composite for the Lithium Ion Battery Anode and Its Electrochemical Performance Evaluation
Authors: Ravikumar Raman , Gopukumar Sukumaran
Published: August 2015

The sulphate doped polypyrrole (PPy) is encapsulated over the tin nano particles using ammonium per sulphates as a polymerizing agent. The XRD, SEM and HRTEM analysis confirms the formation of Sn-PPy composite. Laser Raman and FTIR evidenced for bi-polaron. The conductive PPy prevents the isolation of Sn from the conductive wire, which act as a current collector and backbone as well. The Sn-PPy composites exhibits nominal reversible capacity 698, 878, 791 and 842 mAh g-1 for bare Sn, 80:20, 90:10 and 95:5 Sn-PPy respectively at 100 mA g-1. 80:20 Sn-PPy exhibits superior performance at different current densities. At 400 mA g-1 it delivers ~300 mAh g-1 with the capacity retention of 96% over the studied 50 cycles. The charge transfer resistance for the Sn-PPy 80:20 composite showing comparatively lesser value ~39 Ω. Thus, the composite’s anodic characteristics is well pronounced to be used in lithium ion batteries.
Effect of Contaminants on the Performance of a Proton Exchange Membrane Fuel Cell
Authors: Tavakoli Bahareh , Weidner John W.
Published: August 2015

The overall cost and performance of proton exchange membrane fuel cells (PEMFCs) are an issue of tradeoffs, and the optimal design depends on the application. For example, avoiding degradation via contamination by using expensive materials increases the initial cost to produce the system, but it can extend life and improve the overall performance. This may be desirable where reliability is paramount. In contrast, using less expensive materials reduces the initial cost, but at the expense of the life-time cost of the system and reduced performance. A mathematical model was developed to quantify the performance loss and recovery of the fuel cell by the balance of plant contaminants. This analysis evolved from a systematic and collaborative investigation to understand, characterize, and quantify the degradation mechanisms due to contaminants that arise from components that make up the fuel-cell system. The degradation mechanisms, and the impact to PEMFC performance and durability of each compound was evaluated by infusion of that compound (i.e. 2,6-diaminotoluene , benzyl alcohol, diethylene glycol monoethyl ether and diethylene glycol monoethyl ether acetate) to the cathode side of the fuel cell followed by measuring the fuel cell performance (i.e. current voltage curve, and high frequency impedance resistance).
Design of the Catalyst Layers in PEMFCs Using an Adjoint Sensitivity Analysis Approach
Authors: Andrei Petru , Mixon Grayson , Mehta Mohit , Bevara Vamsci
Published: August 2015

A numerical algorithm is presented for the large-scale optimization of catalyst distribution in proton exchange membrane fuel cells (PEMFCs). The algorithm is based on the evaluation of catalyst sensitivity functions, which show how much the cell voltage or discharge current are increasing when a small amount of catalyst is added at given locations inside the catalyst layers. The catalyst sensitivity functions are evaluated with relatively low computational cost using an adjoint space approach. Using the proposed algorithm one can compute the exact, optimum, three-dimensional (3-D) distribution of platinum particles inside the catalyst layers in order to maximize the overall power density of the cell. It is shown that the optimum distribution depends on the discharge conditions, on the positions of landings and openings, and on the geometry and dimensions of the layers. In general, the optimum catalyst density in the cathode catalyst layer should be larger at the membrane than at the gas diffusion layer interface. In addition, the catalyst density should be slightly larger under the gas channel and smaller under landings.
The Role of Modified Graphene in Cathode Formulations for Lithium-Ion Batteries
Authors: Arbizzani Catia , Da Col Luca , De Giorgio Francesca , Mastragostino Marina , Soavi Francesca
Published: August 2015

We explored the effect of reduced graphene oxide (RGO) on LiNi0.5Mn1.5O4 (LNMO) and on 0.6LiMnPO4–0.4Li3V2(PO4)3 (LMVP) composite cathodes with carbon black (C65). We demonstrated that the effect of RGO depends on the cathode active material. Indeed, RGO improves cycling stability of LNMO cathodes by improving electrode/electrolyte interface stability at high potentials. On the contrary, RGO worsens the performance of LMVP/C65 and it has no effect on LMVP electrodes when it is produced in situ during LMVP synthesis in presence of graphene oxide. Our study indicates that at least 10 wt. % of C65 is necessary for good performance of the poor conductive LMVP.
Aging Modeling of LFP/C Li-ion Cells in Order to Predict Battery Lifetime of an Electric School Bus
Authors: Mingant Rémy , Bernard Julien
Published: August 2015

Electric vehicles (EVs) are frequently seen as a solution in order to answer the several issues raised by conventional cars. The case study of this paper is a school bus using a Li-ion pack including 18650 commercial LFP/C cells arranged in modules. The pack sizing to achieve a target lifetime of 4 years was the scope of this work, and would depend of the results of the cell aging. Therefore, an aging campaign was defined and performed by combining calendar and dynamic EV like tests. The calendar measurements were made on 4 modules of 18 cells connected in parallel and placed in an oven at different states of charge (SoC) and temperatures during 280 days. The cycling aging test was performed on 2 modules of 66 parallel cells with two cycling conditions. In conclusion, the sizing of the battery was chosen with regards to its aging behavior a, life prediction was simulated.
Electrode Kinetics in All-Vanadium Flow Batteries: Effects of Electrochemical Treatment
Authors: Bourke Andrea , Miller Mallory A. , Lynch Robert Patrick , Wainright Jesse S. , Savinell Robert F. , Buckley D. Noel
Published: August 2015

Electrochemical reactions in all-vanadium flow batteries (VFBs) were investigated by examining the effects of electrochemical treatments of carbon on the electrode kinetics of the oxidation-reduction reactions of both VIV/VV and VII/VIII. A range of carbon materials were investigated including carbon fibers, glassy carbon, reticulated vitreous carbon (RVC), carbon paper, and graphite using cyclic voltammetry and electrochemical impedance spectroscopy. In all cases the electrode kinetics of VIV/VV are enhanced by cathodic treatment of the electrode and inhibited by anodic treatment. In contrast, the electrode kinetics of VII/VIII are enhanced by anodic treatment of the electrode and inhibited by cathodic treatment. The observed activation and deactivation effects occur regardless of whether vanadium is present in the electrolyte and are attributed to oxygen-containing functional-groups on the electrode surface. A model was developed based on the rates of oxidation and reduction of active sites on the carbon surface as a function of potential. A good fit of the model to the experimental data was obtained. The surface of carbon felt samples after treatment was analyzed using x-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results highlight the role of oxygen containing functional groups on the activation and deactivation process of the electrode.
Electrochemical Performance of La0.6Sr0.4TixFe1-XO3 -Based Composite Cathode Materials for Solid Oxide Fuel Cells
Authors: Iwai Hiroyuki , Suzuki Shinsuke , Takahashi Yosuke
Published: August 2015

We developed a new cathode material for solid oxide fuel cells containing a composite of La0.6Sr0.4Ti
x
Fe1−x
O3−δ
(0 ≤ x ≤ 0.4) (LSTF) and La0.6Sr0.4CoyFe1−y
O3−δ
(0 ≤ y ≤ 1) (LSCF). Here, we report the results of our performance evaluation of this cathode material. The optimum composition for the composite cathode material was determined to be LSCF 70 wt%–LSTF 30 wt%. Cathodes with this optimum composition exhibited neither fracture nor delamination from the electrolyte during thermal cycling between 200 and 700°C. The developed cathode material also exhibited high power density.
Numerical Investigation of Membrane Dehydration Based on PEM Stack Transient Simulation
Authors: Jia Xiao , Zhou Su
Published: August 2015

In this work, a three-dimensional, serpentine channel, four-cell PEM Stack model including current collector, gas diffusion layer, catalyst layer and membrane has been developed and is used to investigate the effects of membrane dehydration on PEM Stack performance. This numerical study is conducted using finite element method and computational fluid dynamics (CFD) code. To characterize the effects of membrane dehydration, the settings of operating and boundary conditions are not uniform throughout the whole period of simulation. The simulation condition is originally preferable, indicating a normally running stack in healthy status. Further transient simulation has been conducted under four failure conditions with different reactant humidity to monitor the variation of membrane water content and PEM Stack output voltage. The relatively drier reactants carry away more production water, causing the dehydration of membrane and reducing the protonic conductivity. Under a specific demand current, the output voltage of the stack decreases with the process of membrane dehydration, curtailing the maximum power that can be derived from the stack.
Discharge Voltage and Maximum Power Density of Li-Air Batteries with Dual Electrolyte
Authors: Bevara Vamsci , Mehta Mohit , Andrei Petru
Published: August 2015

A new analytical model is developed and a closed-form expression for the discharge voltage and power density of Li-air batteries with mixed electrolyte is derived. Li-air batteries with mixed/dual electrolyte possess the unique advantage of having soluble reaction products at low electrolyte concentrations during discharge. This makes it possible to eliminate some limitation factors by using them as flow batteries. Oxygen diffusion, Butler-Volmer kinetics at the cathode/anode, the resistance of the separator, aqueous electrolyte, solid-electrolyte insulating layer at anode, and the finite conductivity of the electron conductive medium are taken into account. It is shown that the maximum power density depends not only on the internal resistances but also on the oxygen pressure, solubility, and diffusivity in the electrolyte. Results are shown for Li-air batteries with aqueous/basic electrolyte in the cathode but the model can be extended to other metal-air batteries by appropriately adjusting the material constants and geometrical proportions.
Metal Oxide/Reduced Graphene Oxide Anodes for Lithium-Ion Batteries
Authors: Palmieri Alessandro , Liu Ying , He Junkai , Meng Yongtao , Suib Steven , Mustain William E
Published: August 2015

Lithium-Ion Batteries (LIBs) have completely conquered the portable electronic devices market due to their high energy density and cycle life. However, in order to make them suitable for grid-scale or long-range automotive applications, it is necessary to find new materials with higher intrinsic energy density than the state-of-the-art. Metal oxides (MOs) have received considerable attention in recent years as a replacement for graphite at the anode. MOs can provide on average a theoretical capacity around double that of graphite (ca. 700 mAh/g versus 372 mAh/g) and recent studies have shown that acceptable capacity retention can be achieved. Though morphology certainly plays a role in the performance of MO anodes, conductivity is likely the determining factor that dictates material cycleability. Replacement of traditional carbon additives with non-dilutive, high conductive carbons has the potential to yield very high capacity electrodes with excellent capacity retention.
Phase-field Simulation of Lithium Ion Diffusion in Solid Electrolyte Interphase
Authors: Guan Pengjian , Liu Lin
Published: August 2015

Fracture occurs in silicon-based electrodes due to large volume change during the lithiation/delithiation in lithium-ion batteries. A stable solid electrolyte interphase (SEI) can effectively prevent fractures. However, lithium-ion diffusion inside SEI layer has not been fully understood. In this study, a phase-field model is developed to simulate two-dimensional formation of SEI layer and lithium-ion diffusion inside SEI layer formed on silicon electrode. The details of SEI species are confirmed by XPS experiments reported in the literature. Double-well function is applied to represent the total free energy density considering lithium-ion concentration inside the SEI layer. Simulation results show lithium-ion diffusion coefficients between 298K and 318K are 2.021-2.211(10-16) cm2/s, 7.146-8.038(10-13) cm2/s, and 1.448-1.585(10-15) cm2/s for compact, porous, and multilayered SEI layers, respectively. Resistances of the aforementioned SEI layers between 298K and 318K are 1.484-2.609 Ω cm2, 4.175-6.372 Ω cm2, and 5.171-7.007 Ω cm2.
A Novel Two-Step Synthesis for Li2CoPO4F as High-Voltage Cathode Material
Authors: Schoiber Jürgen , Berger Raphael J. F. , Yada Chihiro , Miki Hidenori , Hüsing Nicola
Published: August 2015

Li2CoPO4F has been synthesized via a novel two-step reaction from a solvothermally prepared precursor mixture of LiCoPO4 and LiF. Solvent influences were monitored by powder X-ray diffraction and the reaction conditions for the conversion of the precursor mixture to Li2CoPO4F were optimized. In addition, the obtained materials were characterized before and after carbon-coating by SEM, N2-sorption, elemental and thermogravimetric analysis. The electrochemical performance of the products as high-voltage cathode materials in a coin-cell was tested, and a long term stability over 50 charge/discharge cycles could be demonstrated.
Initial Investigations on the Use of Coated Nano-Sized Phthalocyanines for Very High Energy Density Rechargeable Lithium-Based Batteries
Authors: Fellner Joseph Phillip , Quinton Betty , Tsao Max
Published: August 2015

Phthalocyanines were tested as cathodes in rechargeable lithium ion coin cells. Carbon, in the form of carbon nanotubes, was used to improve the electronic conductivity of phthalocyanine cathode active materials. A protective coating on phthalocyanines was also used to limit undesirable side reactions. Cycling at a depth of near 1000 mAh/g of cathode active material was achieved using two different types of phthalocyanines; iron phthalocyanine and copper phthalocyanine. The following results illustrate that they have great promise as very high energy density rechargeable cathode active material. Improvements in phthalocyanine active material reversibility, capacity, rate, and cycle life are all areas still being investigated.
Electrolyte Additives for Reducing the Irreversible Capacity Loss, Impedance and Polarization of a Doped LiCoPO4 Cathode
Authors: Allen Joshua L. , Allen Jan L. , Delp Samuel A. , Jow T. Richard
Published: August 2015

High voltage cathode materials show promise for improving the specific energy of the state-of-the-art lithium ion battery. One notable cathode material that displays a discharge voltage of ~4.8V, and has the potential to improve the specific energy to ~802Wh/kg, is the olivine-structured LiCoPO4. A significant issue, however, that has plagued LiCoPO4-based systems is the irreversible electrolyte decomposition that occurs at the electrolyte/electrode interface at higher voltages. Electrolyte additives have long been used to improve the passivation layer on the anode, but little is known about the importance of electrolyte additives on the cathode surface. The following study demonstrates a design of experiment (DOE) approach for optimizing the electrolyte additive concentration. The optimized electrolyte improves the cycle life and specific capacity of the cell, while reducing the interfacial impedance. The resulting full-cell containing the optimized electrolyte demonstrates a specific energy that is improved 60% over a full-cell containing the standard electrolyte.
Experimental Investigation of the Influence of the Electrolyte Composition on the Ageing Behavior of Separators in Lithium-Ion Cells
Authors: Kraemer Yvonne , Hintennach Andreas , Meiler Markus
Published: August 2015

The most widely used liquid non-aqueous electrolytes for lithium-ion cells used in electronic consumer and automotive applications consist of lithium hexafluorophosphate (LiPF6) as conductive salt dissolved in a mixture of carbonate esters (cyclic and linear) with the structural unit RO-CO–OR. The separator is a second safety related component in lithium-ion cells, which can be classified into three groups according to the structure: microporous polymer membranes (MPM), non-woven fabric mats (FM) and inorganic composite membranes (ICM). Both non-active components can take part at calendar and cyclic ageing in lithium-ion cells. In this work we report investigations of long-term decomposition reaction mechanisms of a binary electrolyte system. Furthermore, the mutual interaction ageing behavior of both components are investigated.
High Energy Density Electrode Materials for Rechargeable Magnesium Batteries
Authors: Zhang Qing , Takeuchi Esther S , Takeuchi Kenneth J , Marschilok Amy C
Published: August 2015

Rechargeable magnesium batteries are drawing increasing interest as a future alternative to lithium-based batteries due to their high energy density, low environmental impact and low cost. However, the sluggish diffusion of Mg2+ and incompatibility between magnesium anode and traditional electrolytes are hindering the realization of practical magnesium batteries. In this report, we present the preparation, characterization and magnesium electrochemistry of a cathode material, MgxV2O5, and a novel bismuth based composite anode material, Bi-CNT. The MgxV2O5 cathode material was developed via sol-gel route, and it is shown here that the material is of high capacity and favorable for Mg2+ diffusion. The Bi-CNT composite electrode was prepared by electrodeposition, and it shows quasi-reversible electrochemistry and compatibility with non-corrosive electrolyte. The deposition of Bi via a cyclic voltammetry technique was systematically studied, establishing a paradigm for future development of electrodeposited-Bi electrodes.
The Effect of Discharge Products on the Impedance Spectra in Li-Air Batteries with Organic Electrolyte
Authors: Mehta Mohit , Bevara Vamsci V , Andrei Petru
Published: August 2015

The effects of discharge products on the impedance spectra of Li-air batteries with organic electrolyte are studied using finite element simulations. The finite element simulations are based on the theory of concentrated solutions and the complex impedance spectra are computed by linearizing the partial differential equations that describe the mass and charge transport in Li-air batteries. These equations include the oxygen diffusion equation, the Li drift-diffusion equation, and the electron conduction equation. The reaction at the anode and cathode are described by Butler-Volmer kinetics. The total impedance of a Li-air battery increases by more than 200% when the response is measured near the end of the discharge cycle as compared to on a fresh battery. The resistivity of the deposition layer significantly affects the deposition profile and the total impedance. Using electrolytes with high oxygen solubility and concentrated oxygen gas at high pressures will reduce the total impedance of Li-air batteries.
Cathode Dissolution as a Battery Failure Mechanism in Silver Vanadium Oxide (SVO) and Structurally-Stabilized SVO-Analogue Materials Using Phosphate (PO4
3-)
Authors: DeMayo Rachel , Bock David C , Takeuchi Kenneth J , Marschilok Amy C , Takeuchi Esther S
Published: August 2015

Battery failure manifested as an increase in cell impedance as a result of cathode dissolution is discussed. Analogous oxide and phosphate based materials exhibit similar electrochemical performance yet the phosphate based materials display increased structural stability and resistance to solvation formation in non-aqueous electrolytes. Structural modifications could optimize existing battery systems and address one of the main causes of increased cell impedance observed over time.
In-situ Studies of Lithium/Silver Vanadium Phosphorous Oxide Batteries Using Synchrotron based Energy Dispersive X-ray Diffraction
Authors: Li Yue Ru , Kirshenbaum Kevin Charles , Takeuchi Kenneth J , Marschilok Amy C , Takeuchi Esther S
Published: August 2015

The powerful synchrotron analysis technique energy dispersive x-ray diffraction (EDXRD) has been utilized to achieve greater insight into the distribution of silver nanoparticles formed on initial reduction of lithium / silver vanadium phosphorous oxide, Ag2VO2PO4, and silver vanadium diphosphate, Ag2VP2O8, (SVOP family of materials) batteries. By combining the results of EDXRD measurements with ex-situ methods, we are able to effectively probe the discharge mechanism of the bimetallic materials to understand the reduction displacement discharge process.
Generation of AgSi Film by Magnetron Sputtering for Use as Anodes in Lithium Ion Batteries
Authors: Polat Deniz Billur , Eryilmaz Levent , Keles Ozgul
Published: August 2015

In the present work we deposit Si film with 20%at. Ag, to improve the capacity retention and the cycleability of Si anode. The physical properties of the as-synthesized sample are investigated by thin film XRD and SEM. Charge-discharge properties, cyclic voltammetry, electrochemical impedance spectroscopy and cycle performance of the AgSi electrode are examined in detail when used as negative electrode versus lithium. The galvanostatic test result shows that the electrode delivers 1825 mAh g-1 initially with 95% Coulombic efficiency and retains 96% of its initial discharge capacity after 40 cycles. This outstanding coulombic efficiency of the electrode can be related to the presence of Ag, which decreases the polarization of anode.
Improving Electrochemical Performance of Sn Electrode by Sandwich Structure
Authors: Polat Deniz Billur , Bilici Burcin , Keles Ozgul
Published: August 2015

This study explores the electrochemical performance of M/Sn/M (M:Ni and Cu) anodes in rechargeable lithium ion batteries. Sandwich electrode is proposed to improve the electrochemical performance of Sn anode. Herein the electrochemical performances of Cu/Sn/Cu and Ni/Sn/Ni films are compared to that of the pure Sn electrode. The galvanostatic test results prove that stress buffering action of M (M: Cu,Ni), differentiation in the surface reactivity of the electrode, improved the adhesion of the film. After 30 cycle, the capacities of the pure Sn, the Cu/Sn/Cu and the Ni/Sn/Ni films are 22mAh g-1, 140mAh g-1, 205 mAh g-1 respectively. It is demonstrated that the sandwich model improves cycle performance of the electrode.
Oxygen-deficient Niobium Oxide in Carbon Matrix as Anode for Lithium-Ion Battery
Authors: Yan Litao , Chen Gen , Zhou Meng , Luo Hongmei
Published: August 2015

Oxygen-deficient Nb2O5-x/carbon matrix using glucose as the carbon source was prepared by hydrothermal method followed by thermal treatment. Nb2O5-x resulted from partially reduced stoichiometric Nb2O5. Carbon matrix can efficiently prevent Nb2O5-x nanocrystals from pulverization during the charge-discharge processes, resulting in enhanced rate capacity and recyclability.
Effect of Cathode Slurry Composition on the Electrochemical Properties of Li-Ion Batteries
Authors: Dermenci Kamil Burak , Turan Servet , Behm Mårten , Lindbergh Göran
Published: August 2015

The performance difference between commercial and laboratory scale cells remains a problem to be solved. Different way of battery electrode preparation is considered to be the main reason underlying various battery performance. In this work, the effect of slurry compositions on electrochemical properties of Li-ion batteries is reported. Slurry preparation with various compositions of LiFePO4 active material (76-88%), PVdF binder (6-12%) and Super P Carbon conductive additive (6-12%) has been studied. Charge-discharge curves and capacity fade of electrodes are also investigated. Selected electrodes were pressed in order to see the effect of pressing on the final performance. Results showed that varying PVdF and carbon content mainly effects charge-discharge characteristics. For unpressed samples, higher amount of PVdF and carbon could result higher maximum specific capacity and lower internal resistance during lithiation and delithiation of positive electrode. Pressing reduces the distance between slurry particles, which enhances the conductivity of the prepared cell