bluuebunny/crossref_metadata_2025 huggingface dataset:
Measured backscattering of a first order vortex beam by a sphere with helicity selective processing and imaging
Authors: Bollen Viktor , Plotnick Daniel S. , Zartman David J. , Marston Philip L.
Published: May 2015

An acoustic vortex beam’s wavefield has a null on the axis of propagation and an angular phase ramp. A four-element transducer generates a first order vortex beam in water by appropriately phasing each element [V. Bollen et al., Proc. Meet. Acoust. 19, 070075 (2013)]. A differential beam having a broader null may also be produced by exciting two elements out-of-phase. The four-element transducer was also used to measure backscattering by a small solid sphere scanned in a raster pattern and insonified by the vortex beam. By independently recording each of the four elements and adding appropriate time delays in post-processing, the scattering may be measured in a helicity neutral, and co- and cross-helicity sensitive modes; this allows the retention of the vortex source without modifying the experimental setup. Due to the rapid phase change on the axis of the beam, subwavelength resolution of the null location of the sphere can be achieved. By applying a time delay-and-sum imaging algorithm this resolution can be further increased. Three-dimensional images can also be constructed from the data. By driving two opposing elements, the tilt of the transducer with respect to the scanning plane can be inferred, aiding alignment. [Work supported by ONR.]
Modes of plates and shells in water driven by modulated radiation pressure of focused ultrasound
Authors: Daniel Timothy D. , Marston Phil L. , Abawi Ahmad T. , Kirsteins Ivars
Published: May 2015

We used modulated radiation pressure of focused ultrasound to excite resonant flexural vibrations of an aluminum circular plate in water. The source transducer was driven with a double-sideband suppressed carrier voltage as previously used for exciting low-frequency modes of liquid drops [P. L. Marston and R. E. Apfel, J. Acoust. Soc. Am. 67, 27–37 (1980)]. The response of the target (detected with a hydrophone) was at twice the modulation frequency and proportional to the square of the drive voltage. Due to the spatially localized nature of the radiation pressure of the focused beam, mode shapes could be identified by scanning the source along the target while measuring the target’s response. Additional measurements were done with an open-ended water-filled copper circular cylindrical shell in which resonant frequencies and mode shapes were also identified. These experiments illustrate how high-frequency focused sound can be used to identify relatively low-frequency modes of elastic objects without direct contact. [Work supported by ONR.]
A comparison between flexible disk transducer cavitation measurements and predictions
Authors: Horbach Arthur , McEachern James
Published: May 2015

An investigation of the threshold of cavitation of flexible disk transducers used as underwater acoustic sources was conducted. The principal task was the estimation of the cavitation threshold in sound pressure level (SPL) of an individual transducer as a function of operating depth and the actual measurement of the cavitation threshold. The transducers under test were driven at a series of voltage levels, using CW pulse lengths of 50 and 100 ms. these drive voltages were increased in steps and the received signals were analyzed for total harmonic distortion (THD), transmitting voltage response (TVR), output SPL, and voltage-current phase angle, all as a function of depth. The onset of cavitation on the flex disk is well defined in terms of THD. Comparing the measured values for the onset of cavitation to those predicted by an expression recommended by Sherman and Butler, a value of the cavitation parameter, gamma, was determined to be about 0.36, consistent with, and bracketed by, their values, for a number of transducer shapes. predictions of cavitation threshold versus depth for the flexible disk transducer were within 1 to 2 dB of measured results.
Performance Analysis of Elite Female Amateur Boxers and Comparison With Their Male Counterparts
Authors: Davis Philip , Benson Peter R. , Waldock Robert , Connorton Andrew J.
Published: May 2015

Female boxing debuted at the 2012 London Olympic Games. To better understand the performance aspects of the sport, video footage of eighteen 4 × 2-min bouts were analyzed. The boxers involved in the competition were of an elite level (mean ± SD), age 26.4 ± 4.6 y, height 169.3 ± 6.2 cm, and weight 60.3 ± 10.0 kg. Analysis revealed an activity rate of ~1.6 actions/s, including ~16 punches, ~3.3 defensive movements, and ~63 vertical hip movements, all per minute, over the 4 × ~132-s rounds (R). A 2 × 4 (outcome × round) ANOVA with repeated measures over the rounds was used to analyze the data. Winners maintained a higher activity rate in round 1 (R1) and R2; a higher movement rate in R2, R3, and R4; and an increased punch accuracy including the ratio of total punches to punches landed in R3 and air punches as a percentage of punches missed in R1 and R3. Specific techniques that discriminate between successful and unsuccessful female amateur boxers include the straight rear-hand and body punches, higher for winners in R1, as well as uppercut punches and defensive foot movements, higher for winners in R4. Findings highlight the current demands of elite amateur female boxing. These data will be useful for those designing training programs and may also be useful for guiding sport-specific fitness testing.
Anthropometrics of Italian Senior Male Rugby Union Players: From Elite to Second Division
Authors: Fontana Federico Y. , Colosio Alessandro , De Roia Gabriela F. , Da Lozzo Giorgio , Pogliaghi Silvia
Published: May 2015

Anthropometric evaluation of athletes is necessary to optimize talent identification and player development.

Objectives:

To provide a specific anthropometric reference database of senior male rugby players competing at different levels in the southern European region.

Design:

Cross-sectional.

Methods:

In 362 professional players (25 ± 4 y; 138 Italian national team, 97 first-division, and 127 second-division national championships) the authors measured mass, stature, and percentage body fat (plicometry). Mean, SD, and coefficient of variation were calculated for forwards and backs and for positional subgroups. Binomial logistic regression and receiver-operating-characteristic curve were performed to assess which variables best predicted level assignment (international vs national level).

Results:

For all competitive levels forwards were significantly heavier and taller and had a larger percentage body fat and fat-free mass than backs. The lower the competitive level, the higher the within-role variability observed; furthermore, players in a specific positional subgroup were lighter, shorter, and fatter and had less fat-free mass. Fat-free mass is the variable that best predicts the likelihood of being classified as an international or national player (cutoff value 79.54 kg).

Conclusions:

The data confirm the specificity in the physical requirements of rugby in individual playing positions at all competitive levels and document significant differences among elite and 1st- and 2nd-division players in the same positional role. These differences may reflect the variable technical abilities, selection, training practices, and requirements of the game among these categories.
The stroma gives tumors a dose of drug tolerance
Authors: Ferrarelli Leslie K.
Published: April 2015

Blocking the kinase FAK may prevent fibroblasts from enabling resistance to BRAF inhibitors in melanomas.
Genome Sequence of a Novel Iflavirus from the Leafhopper
Graminella nigrifrons
Authors: Chen Yuting , Liu Sijun , Bonning Bryony C.
Published: May 2015

A novel iflavirus was discovered from the transcriptome of the leafhopper
Graminella nigrifrons
. The assembled virus genome has 9,700 nucleotides (nt) and encodes a 3,035-amino-acid polyprotein. Sanger sequencing was used to confirm the sequence encoding the polyprotein and indicated a genome length of 9,617 nt with a polyadenylated tail.
Whole-Genome Sequence of an Epidemic Strain of Burkholderia pseudomallei vgh07 in Taiwan
Authors: Chen Yao-Shen , Lin Hsi-Hsun , Hsueh Pei-Tan , Liu Pei-Ju , Ni Wen-Fan , Chung Wan-Chia , Lin Chih-Peng , Chen Ya-Lei
Published: May 2015

Here, we report the complete genome sequence of
B. pseudomallei
vgh07. This is an epidemic strain that was isolated from a melioidosis patient with arthro-osteomyelitis in Taiwan.
Genome Sequence of Classical Swine Fever Virus Genotype 1.1 with a Genetic Marker of Attenuation Detected in a Continuous Porcine Cell Line
Authors: Tomar N. , Gupta A. , Arya R. S. , Somvanshi R. , Sharma V. , Saikumar G.
Published: May 2015

The complete genome sequencing and analysis of a classical swine fever virus (CSFV) detected in a porcine kidney cell line revealed a close relationship with genotype 1.1 viruses circulating in India and China. The presence of consecutive T insertions in the 3′ untranslated region (UTR), as seen in vaccine strains of CSFV, suggested some degree of attenuation.
Complete Genome Sequence of a Coxsackievirus A16 Strain, Isolated from a Fatal Case in Shenzhen, Southern China, in 2014
Authors: Chen Long , Yang Hong , Feng Qian-Jin , Yao Xiang-Jie , Zhang Hai-Long , Zhang Ren-Li , He Ya-Qing
Published: May 2015

We determined the complete genome sequence of a coxsackievirus A16 strain (CVA16/SZ29/CHN/2014) from a fatal case in Shenzhen, southern China, in 2014. The strain was assigned to subgenotype B1b based on phylogenetic analysis of the VP1 gene.
First Insights into the Genome of the
N
-Methylhydantoin-Degrading
Clostridium
sp. Strain FS41 (DSM 6877)
Authors: Poehlein Anja , Bandera Adrian , Horne Deborah , Maier Joachim , Pawlowicz David , Siebert Verena , Daniel Rolf
Published: May 2015

Clostridium
sp. strain FS41 (DSM 6877) is a strictly anaerobic and Gram-positive spindle-shaped rod. This spore-forming bacterium is able to degrade
N
-methylhydantoin, with
N
-carbamoylsarcosine and sarcosine as intermediates. The genome consists of one replicon (6.28 Mb) and harbors 5,735 predicted protein-coding genes.
Draft Genome Sequences of Histamine-Producing Photobacterium kishitanii and Photobacterium angustum, Isolated from Albacore (
Thunnus alalunga
) and Yellowfin (
Thunnus albacares
) Tuna
Authors: Bjornsdottir-Butler Kristin , McCarthy Susan A. , Dunlap Paul V. , Timme Ruth E. , Benner Ronald A.
Published: May 2015

Histamine-producing bacteria are responsible for scombrotoxin (histamine) fish poisoning, a leading cause of fish poisoning in the United States. We report here the draft genome sequences of four histamine-producing (HP)
Photobacterium kishitanii
strains and nine HP
Photobacterium angustum
strains isolated from tuna.
Activation of Toxin-Antitoxin System Toxins Suppresses Lethality Caused by the Loss of σ
E
in Escherichia coli
Authors: Daimon Yasushi , Narita Shin-ichiro , Akiyama Yoshinori
Published: April 2015

σ
E
, an alternative σ factor that governs a major signaling pathway in envelope stress responses in Gram-negative bacteria, is essential for growth of
Escherichia coli
not only under stressful conditions, such as elevated temperature, but also under normal laboratory conditions. A mutational inactivation of the
hicB
gene has been reported to suppress the lethality caused by the loss of σ
E
.
hicB
encodes the antitoxin of the HicA-HicB toxin-antitoxin (TA) system; overexpression of the HicA toxin, which exhibits mRNA interferase activity, causes cleavage of mRNAs and an arrest of cell growth, while simultaneous expression of HicB neutralizes the toxic effects of overproduced HicA. To date, however, how the loss of HicB rescues the cell lethality in the absence of σ
E
and, more specifically, whether HicA is involved in this process remain unknown. Here we showed that simultaneous disruption of
hicA
abolished suppression of the σ
E
essentiality in the absence of
hicB
, while ectopic expression of wild-type HicA, but not that of its mutant forms without mRNA interferase activity, restored the suppression. Furthermore, HicA and two other mRNA interferase toxins, HigB and YafQ, suppressed the σ
E
essentiality even in the presence of chromosomally encoded cognate antitoxins when these toxins were overexpressed individually. Interestingly, when the growth media were supplemented with low levels of antibiotics that are known to activate toxins,
E. coli
cells with no suppressor mutations grew independently of σ
E
. Taken together, our results indicate that the activation of TA system toxins can suppress the σ
E
essentiality and affect the extracytoplasmic stress responses.

IMPORTANCE
σ
E
is an alternative σ factor involved in extracytoplasmic stress responses. Unlike other alternative σ factors, σ
E
is indispensable for the survival of
E. coli
even under unstressed conditions, although the exact reason for its essentiality remains unknown. Toxin-antitoxin (TA) systems are widely distributed in prokaryotes and are composed of two adjacent genes, encoding a toxin that exerts harmful effects on the toxin-producing bacterium itself and an antitoxin that neutralizes the cognate toxin. Curiously, it is known that inactivation of an antitoxin rescues the σ
E
essentiality, suggesting a connection between TA systems and σ
E
function. We demonstrate here that toxin activation is necessary for this rescue and suggest the possible involvement of TA systems in extracytoplasmic stress responses.
Placental mesenchymal dysplasia associated with spontaneous ovarian hyperstimulation syndrome
Authors: Davoudian Payam
Published: April 2015

Placental mesenchymal dysplasia (PMD) is a rare disorder of unknown aetiology characterised by placentomegaly, serpiginous surface blood vessels and large cystic villi. Although a mimic of molar pregnancies and other entities, it can be distinguished from them by its association with intrauterine growth restriction or death of a relatively normal fetus and its characteristic histopathology. We report the case of a 20-year-old primigravida who presented at 16 weeks with heavy clotty vaginal bleeding and subsequent miscarriage. The placenta was grossly abnormal and resembled a partial molar pregnancy. PMD was confirmed by microscopic examination. Postmiscarriage, ultrasound revealed enlarged and multicystic ovaries similar to those seen in ovarian hyperstimulation syndrome (OHSS), which returned to normal a few weeks after miscarriage. This is the first report of PMD associated with OHSS, and we hypothesise that the most likely pathogenesis is ovarian stimulation from PMD-derived vascular endothelial growth factor.
Erectile dysfunction: a window to the heart
Authors: Androshchuk Vitaliy , Pugh Neil , Wood Andrew , Ossei-Gerning Nick
Published: April 2015

Erectile dysfunction (ED) is an early marker of coronary artery disease (CAD) and often manifests before the development of symptomatic CAD. In this case report, we present a 60-year-old man with ED, who demonstrated limited response to the standard management strategies and was subsequently treated with percutaneous pelvic intervention (PPI) of the internal pudendal artery. While on the table for PPI, the patient described a classical history of angina, on which basis he underwent coronary angiography and was found to have narrow proximal left anterior descending stenosis. Coronary artery stent placement was then performed using standard techniques. PPI of pudendal artery stenoses with stents is feasible and can improve cavernosal blood flow and venous leakage as well as erectile function.
Protolith of ultramafic rocks in the Kluane Schist, Yukon, and implications for arc collisions in the northern Cordillera
Authors: Canil Dante , Johnston Stephen T. , D’Souza Rameses J. , Heaman Larry M.
Published: May 2015

Mafic and ultramafic rocks crop out as decimetre- to centimetre-sized bodies of talc–antigorite–olivine (±orthopyroxene) and chlorite–amphibole schists interleaved in the pelitic Kluane Schist of southwestern Yukon. The metamorphic assemblages in ultramafic rocks exposed at Doghead Point overprint two generations of cleavage and are consistent with metamorphism reaching >550 °C (talc + olivine) and >750 °C (olivine + enstatite) in the contact aureole of the Eocene Ruby Range batholith. The bulk rock major and trace element patterns in the ultramafic schists (>40 wt.% MgO, Mg/(Mg + Fe) > 0.90) are unlike residual mantle from partial melting (i.e., ophiolite, orogenic massif, abyssal ocean floor) but are similar to peridotite or pyroxenite cumulates from arc magmas. Identical trace element concentrations and patterns are observed in several late Triassic basalts, pyroxenites, and websterites occurring to the southeast in Stikinia (present coordinates). A highly discordant U–Pb zircon date for one antigorite–talc–olivine schist sample (200–210 Ma) is within the range of U–Pb zircon ages for the late Triassic Lewes River – Stuhini arc in northwestern Stikinia (200–208 Ma, 216–220 Ma). When combined with other published age information, the ultramafic rocks in the Kluane Schist are interpreted as fragments of deeper arc-related mafic and ultramafic intrusive rocks introduced to the Kluane forearc basin between 95 and 82 Ma by exhumation along shear zones in northwestern Stikinia, most likely the Wann River or Llewellyn Faults. The Kluane Schist represents a west-facing forearc basin bordered to the east by arc-parallel strike-slip fault(s) that served to exhume and imbricate large knockers into the accretionary prism.
A meme propagation model to combine social affirmation with meme attractiveness and persistence
Authors: Zheng Aiguo , Luo Shuangling , Xia Haoxiang
Published: April 2015

The propagation of memes on online social networks often depends on the mechanism of social affirmation. Centola termed such social-affirmation-driven diffusion as complex contagion and partly validated it through an online experiment. However, for actual online meme propagation, the mechanism of social affirmation often takes effect in combination with various other factors and mechanisms. In this paper, we examine the combinatorial effects of social affirmation and the attractiveness and persistence of the meme by proposing and analyzing a UACI model, where an agent’s activities to receive and transfer a meme is associated with the transition between its four possible states of “Uninformed”, “Attended”,“Convinced” and “Immune”. The numerical simulations illustrate nontrivial patterns of propagation. Especially, it is revealed that the effects of simple and complex contagions co-exist and equilibrate in accordance with the joint functions of meme attractiveness and social affirmation. Furthermore, the low-persistence of the meme hinders the propagation-scale more remarkably on the regular network than on the random one, indicating that the persistence may be critical for retaining complex contagion.
Real hypersurfaces in complex two-plane Grassmannians with recurrent Ricci tensor
Authors: Suh Young Jin , Hwang Doo Hyun , Woo Changhwa
Published: April 2015

In this paper, we have introduced a new notion of generalized Tanaka–Webster Reeb recurrent Ricci tensor of real hypersurfaces in complex two-plane Grassmannians G2(ℂm+2). Next, we show a non-existence property for real hypersurfaces M in G2(ℂm+2) with such a curvature condition.
Examples of real hypersurfaces with two principal curvatures in complex projective planes
Authors: Díaz Ramos J. Carlos , Vidal-Castiñeira Cristina
Published: April 2015

We give examples of real hypersurfaces with two distinct principal curvatures in the complex projective plane ℂP2.
Hedge Fund Characteristics and Performance Persistence: Evidence from 1996–2006
Authors: Kumar Pavitra
Published: April 2015

This paper investigates the association between selected hedge fund characteristics and persistence in both positive and negative abnormal returns using data from the TASS database between 1996 and 2006. I find that higher fund age, size and illiquidity, after controlling for risk, generate stronger persistence in both short- and long-term positive abnormal returns, or good performance. Therefore, these features appear to signal superior managerial and/or fund skill. Furthermore, funds with higher incentive fees display greater long-run persistence in both good and bad performance, net of fees. These results suggest that incentive fees are increased by both skilled and unskilled, but lucky, funds following good past performance.
Design Optimization of Mixed-Criticality Real-Time Embedded Systems
Authors: Tămaş-Selicean Domiţian , Pop Paul
Published: May 2015

In this article, we are interested in implementing mixed-criticality real-time embedded applications on a given heterogeneous distributed architecture. Applications have different criticality levels, captured by their Safety-Integrity Level (SIL), and are scheduled using static-cyclic scheduling. According to certification standards, mixed-criticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We consider that the separation is provided by partitioning, such that applications run in separate partitions, and each partition is allocated several time slots on a processor. Tasks of different SILs can share a partition only if they are all elevated to the highest SIL among them. Such elevation leads to increased development costs, which increase dramatically with each SIL. Tasks of higher SILs can be decomposed into redundant structures of lower SIL tasks. We are interested to determine (i) the mapping of tasks to processors, (ii) the assignment of tasks to partitions, (iii) the decomposition of tasks into redundant lower SIL tasks, (iv) the sequence and size of the partition time slots on each processor, and (v) the schedule tables, such that all the applications are schedulable and the development costs are minimized. We have proposed a Tabu Search-based approach to solve this optimization problem. The proposed algorithm has been evaluated using several synthetic and real-life benchmarks.
Analytical Reliability Analysis of 3D NoC under TSV Failure
Authors: Khayambashi Misagh , Yaghini Pooria M. , Eghbal Ashkan , Bagherzadeh Nader
Published: April 2015

The
network-on-chip
(NoC) technology allows for integration of a manycore design on a single chip for higher efficiency and scalability.
Three-dimensional
(3D) NoCs offer several advantages over
two-dimensional
(2D) NoCs.
Through-silicon via
(TSV) technology is one of the candidates for implementation of 3D NoCs. TSV reliability analysis is still challenging for 3D NoC designers because of their unique electrical, thermal, and physical characteristics. After providing an overview of common TSV issues, this article aims to define a reliability criterion for NoC and provide a framework for quantifying this reliability as it relates to TSV issues. TSV issues are modeled as a time-invariant failure probability. Also, a reliability criterion for TSV-based NoC is defined. The relationship between NoC reliability and TSV failure is quantified. For the first time, the reliability criterion is reduced to a tractable closed-form expression that requires a single Monte Carlo simulation. Importantly, the Monte Carlo simulation depends only on network geometry. To demonstrate our proposed method, the reliability criterion of a simple 8×8×8 NoC supported by an 8×8×7 network of TSVs is calculated.
Scalable Game Design
Authors: Repenning Alexander , Webb David C. , Koh Kyu Han , Nickerson Hilarie , Miller Susan B. , Brand Catharine , Horses Ian Her Many , Basawapatna Ashok , Gluck Fred , Grover Ryan , Gutierrez Kris , Repenning Nadia
Published: May 2015

An educated citizenry that participates in and contributes to science technology engineering and mathematics innovation in the 21st century will require broad literacy and skills in computer science (CS). School systems will need to give increased attention to opportunities for students to engage in computational thinking and ways to promote a deeper understanding of how technologies and software are used as design tools. However, K-12 students in the United States are facing a broken pipeline for CS education. In response to this problem, we have developed the Scalable Game Design curriculum based on a strategy to integrate CS education into the regular school curriculum. This strategy includes opportunities for students to design and program games and science technology engineering and mathematics simulations. An approach called Computational Thinking Pattern Analysis has been developed to measure and correlate computational thinking skills relevant to game design and simulations. Results from a study with more than 10,000 students demonstrate rapid adoption of this curriculum by teachers from multiple disciplines, high student motivation, high levels of participation by women, and interest regardless of demographic background.
Parallel processing with promises
Authors: Rathbun Spencer
Published: April 2015

A simple method of writing a collaborative system.
High performance spatial queries for spatial big data
Authors: Wang Fusheng , Aji Ablimit , Vo Hoang
Published: April 2015

Support of high performance queries on large volumes of spatial data has become increasingly important in many application domains, including geospatial problems in numerous disciplines, location based services, and emerging medical imaging applications. There are two major challenges for managing massive spatial data to support spatial queries: the explosion of spatial data, and the high computational complexity of spatial queries. Our goal is to develop a general framework to support high performance spatial queries and analytics for spatial big data on MapReduce and CPU-GPU hybrid platforms. In this paper, we introduce Hadoop-GIS -- a scalable and high performance spatial data warehousing system for running large scale spatial queries on Hadoop. Hadoop-GIS supports multiple types of spatial queries on MapReduce through skew-aware spatial partitioning, on-demand indexing, customizable spatial query engine RESQUE, implicit parallel spatial query execution on MapReduce, and effective methods for amending query results through handling boundary objects. To accelerate compute-intensive geometric operations, GPU based geometric computation algorithms are integrated into MapReduce pipelines. Our experiments have demonstrated that Hadoop-GIS is highly efficient and scalable, and outperforms parallel spatial DBMS for compute-intensive spatial queries.
Large-scale spatial data processing on GPUs and GPU-accelerated clusters
Authors: Zhang Jianting , You Simin , Gruenwald Le
Published: April 2015

The massive data parallel computing power provided by inexpensive commodity Graphics Processing Units(GPUs) makes large-scale spatial data processing on GPUs and GPU-accelerated clusters attractive from both a research and practical perspective. In this article, we report our works on data parallel designs of spatial indexing, spatial joins and several other spatial operations, including polygon rasterization, polygon decomposition and point interpolation. The data parallel designs are further scaled out to distributed computing nodes by integrating single-node GPU implementations with High-Performance Computing (HPC) toolset and the new generation in-memory Big Data systems such as Cloudera Impala. In addition to introducing GPGPU computing background and outlining data parallel designs for spatial operations, references to individual works are provided as a summary chart for interested readers to follow more details on designs, implementations and performance evaluations.
Emerging trends in monitoring landscapes and energy infrastructures with big spatial data
Authors: Bhaduri Budhendra , Patlolla Dilip , Vatsavai Ranga R. , Cheriyadat Anil , Lu Wei , Karthik Rajasekar
Published: April 2015

Explosion of spatial data from satellite to citizen sensors has posed the critical challenge of Big Spatial Data integration, analysis, and visualization. This article focuses on research and development activities at Oak Ridge National Laboratory (ORNL) that are addressing end-user applications utilizing high performance computing based geospatial science and technology solutions to optimize the analysis, modeling, and multi-megapixel scale visualization of the geospatial data. Specifically we highlight recent developments and successes in the areas of high resolution settlement mapping, transportation and mobility analysis, and effective monitoring of biomass for energy and food security.
Factors Affecting Spectroscopic State-of-Charge Measurements of Positive and Negative Electrolytes in Vanadium Redox Flow Batteries
Authors: Quill Nathan , Petchsingh Cattleya , Lynch Robert P. , Gao Xin , Oboroceanu Daniela , Ní Eidhin Deirdre , O'Mahony Marcus , Lenihan Catherine , Buckley D. Noel
Published: May 2015

We showed that it is easy, in principle, to measure the state of charge (SoC) of VRFB negative electrolytes by ultraviolet-visible (UV-Vis) absorption spectroscopy because the spectra are a linear combination of the spectra of the components, VII and VIII. In contrast we showed, for a range of mole percentages of VV at several different concentrations of total vanadium, that the UV-Vis spectra of the positive electrolyte do not exhibit a similar linearity and that absorbance measurements at two different wavelengths are required to measure the SoC. All positive electrolytes showed an excess absorbance A
ex which we have proposed to be proportional to the concentration of a 1:1 mixed-valence complex V2O3
3+ in equilibrium with VO2+ and VO2
+. We have defined a parameter p which directly relates A
ex to the vanadium concentration C and the mole percentage of VV (i.e. the SoC). We showed that at any given wavelength, the value of p decreases somewhat with C. This is consistent with our model, when the variation of the V2O3
3+ equilibrium constant K
c with C is small. We estimated approximate values for K
c and for the excess molar extinction coefficient ε
ex.
Kinetic Studies on State of the Art Solid Oxide Cells – A Comparison between Hydrogen/Steam and Reformate Fuels
Authors: Njodzefon Jean-Claude , Graves Christopher , Mogensen Mogens Bjerg , Weber André , Hjelm Johan
Published: May 2015

Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen/steam and reformate fuels hydrogen/carbon-dioxide and hydrogen/methane/steam. It was found that the kinetics at the fuel electrode were exactly the same in both reformates. The hydrogen/steam fuel displayed slightly faster kinetics than the reformate fuels. Furthermore the gas conversion impedance in the hydrogen/steam fuel split into two processes with opposing temperature behavior in the reformate fuels. An 87.5% reduction in active electrode area diminishes the gas conversion impedance in the hydrogen/steam fuel at high fuel flow rates. In both reformates, the second and third lowest frequency processes merged into a single process as the gas conversion was reduced. The SOC with finer electrode microstructure displayed improved kinetics.
Strategies to Optimize Performance of Lithium-Ion Supercapacitors: Screening of Cathode Configuration, Anode Pre-Lithiation Loading and Separator Type
Authors: Cao Wanjun , Li Yangxing , Fitch Brian , Shih Jonathan , Doung T , Zheng Jim P
Published: May 2015

The Li-ion capacitor (LIC) is composed of a lithium-doped carbon anode and an activated carbon cathode, which is a half Li-ion battery (LIB) and a half electrochemical double-layer capacitor (EDLC). LICs can achieve much more energy density than EDLC without sacrificing the high power performance advantage of capacitors over batteries. LIC pouch cells were assembled using activated carbon (AC) cathode and hard carbon (HC) + stabilized lithium metal power (SLMP®) anode. Different cathode configurations, various SLMP loadings on HC anode, and two types of separators were investigated to achieve the optimal electrochemical performance of the LIC. Firstly, the cathode binders study suggests that the PTFE binder offers improved energy and power performances for LIC in comparison to PVDF. Secondly, the mass ratio of SLMP to HC is at 1:7 to obtain the optimized electrochemical performance for LIC among all the various studied mass ratios between lithium loading amounts and active anode material. Finally, compared to the separator Celgard PP 3501, cellulose based TF40-30 is proven to be a preferred separator for LIC.
Supercapacitors Based on Mixture of Room Temperature Ionic Liquids Containing Specifically Adsorbed Iodide Anions
Authors: Thomberg Thomas , Tooming Tauno , Liivand K , Siinor Liis , Jänes Alar , Lust Enn
Published: May 2015

The influence of 5 wt% addition of 1-ethyl-3-methylimidazolium iodide (EMImI) in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) on the melting point, bulk conductivity and electrochemical properties of the ionic liquid mixture as an electrolyte in electrical double layer capacitor (EDLC) has been studied using cyclic voltammetry, electrochemical impedance spectroscopy, constant current charge-discharge and constant power discharge methods. The specific conductivity decreased from 13.6 mS cm-1 to 12.8 mS cm-1 and the melting point increased from 17°C to 19.5°C by adding 5 wt% of EMImI into EMImBF4. Noticeable increase in specific capacitance up to 245 F g-1 at 1.0 V, specific energy (36.7 Wh kg-1) and specific power values has been established. Thus, EDLC based on EMImBF4 + EMImI mixture demonstrated nearly 50% higher stored charge value than EDLC without EMImI addition. However, only minor increase in characteristic relaxation time constant from 1.45 s to 1.48 s for EDLC based on I- adsorption effect has been established.
Separator Materials Influence on Supercapacitors Performance in Viscous Electrolytes
Authors: Liivand Kerli , Thomberg Thomas , Jänes Alar , Lust Enn
Published: May 2015

Influence of separator material on the high and low frequency series resistance, characteristic time constant, energy and power densities of the supercapacitors (SCs), based on two identical ideally polarizable microporous titanium carbide-derived carbon electrodes in different electrolytes: 1M (C2H5)3CH3NBF4 in acetonitrile (AN) solution, 1M (C2H5)3CH3NBF4 in dimethyl carbonate, ethylene carbonate and propylene carbonate (DMC:EC:PC) mixture, and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, has been tested by cyclic voltammetry, electrochemical impedance spectroscopy, and constant power discharge methods. Four different separator materials were studied, two commercial ones TF4425 and Celgard2400, and two self-made PVDF membranes with different morphologies. Influence of temperature on the SC characteristics has been performed at +24 and -30 °C with SCs completed with 1M (C2H5)3CH3NBF4 in AN and in DMC:EC:PC electrolytes. It was established that the separator material structure and chemical composition noticeably influences the high frequency series resistance, phase angle, characteristic time constant and power density values of SC.
Nanocolumnar-Architectured, Layered Cu/Si Film as Anodes for Rechargeable LIB
Authors: Polat Deniz Billur , Keles Ozgul
Published: May 2015

In this work, we produce layered Cu/Si film by deposition a thin Cu film on Si nanocolums by an oblique angle deposition method. Galvanostatic half-cell measurements show that, the Cu coated Si nanocolumn arrays performs 1700 mAh g-1 in the first cycle, then after 10 cycles its performance is stabilized to 500 mAh g-1 with 99% coulombic efficiency for 90 cycles. This high performance is related to its particular morphology and physical properties. First, having homogenously distributed nano-sized porosities in the Cu coated film increases the mechanical tolerance of the electrode against the volumetric changes occurred during galvanostatic test. Second, the ductile behavior of the Cu film holds the electrode together to prevent the electronic isolation, pulverization or delamination of the coating. Third, Cu15Si4 intermetallics increase the mechanical resistances of the coating against the stress generated in the electrode. Last, the surface reactivity of the electrode, hence its interaction with the electrolyte, is also changedbecause of the Cu layer presence as interlayer, leading to higher coulombic efficiency once a stable SEI forms on the anode.
Degradation Analyses of Commercial Lithium-Ion Cells by Temperature/C-rate Controlled Cycle Test
Authors: Matsuda Tomoyuki , Myojin Masao , Ando K , Imamura Daichi
Published: May 2015

Cycle life tests of commercial 18650-type lithium-ion cells were conducted at temperatures of 0°C, 25°C, and 45°C and current rates of 1 C and 2 C. Surprisingly, the discharge capacity rapidly decreased at 0°C regardless of the current rate. On the other hand, the discharge capacity decreased faster at 45°C than at 25°C for a rate of 1 C, and this decrease was faster at 25°C than 45°C for a rate of 2 C. Electrodes and electrolytic solutions of the degraded cells were characterized by several analytical methods. X-ray photoelectron spectroscopy revealed differences between solid electrolyte interface components according to test temperature. The carbonate ratio was high at low temperature while the phosphate ratio was high at elevated temperature. The observed cell degradations were caused by several factors exhibiting various temperature and current rate dependencies.
Effect of Electrode Mixing Conditions on the Performance of Lithium-Ion Batteries Analyzed by Fast Fourier Transform Electrochemical Impedance Spectroscopy
Authors: Nakajima Hironori , Kitahara Tatsumi , Higashinaka Yuta , Nagata Yusaku
Published: May 2015

We have investigated the influence of mixing conditions during the positive electrode fabrication on the discharge performance and internal resistances under high rate discharge of a test lithium-ion battery at 30 °C, employing fast Fourier transform electrochemical impedance spectroscopy in-situ to minimize the change in the state of charge. The internal resistances are assigned to each component in the positive electrode by comparing with cross-sectional scanning electron micrographs. The mixings of the active material and conductive filler with too low rotating speed both before and after the addition of the binder and solvent, pre-mixing and slurry mixing, respectively, give smaller active contact area between agglomerated conductive filler and the active material, leading to larger interfacial resistance. The pre-mixing and slurry mixing under too high rotating speed both result in larger interfacial resistances due to poor contacts of agglomerated active material with the conductive filler and the electrolyte.
In-Production Recycling of Active Materials from Lithium-Ion Battery Scraps
Authors: Hanisch Christian , Schünemann Jan-Hinnerk , Diekmann Jan , Westphal Bastian , Loellhoeffel Thomas , Prziwara Paul Fabio , Haselrieder Wolfgang , Kwade Arno
Published: May 2015

Having a closer look at the details, recycling of scraps from the production of lithium-ion batteries is different from recycling of spent batteries. On the one hand it is less dangerous on the other hand pristine electrodes retain the original non-aged quality and thus the separation process is more difficult. Two different separation mechanisms, one mechanical and one based on the solvent N-methyl-2-pyrrolidone, are examined in this work. The resulting separated coatings are directly re-applied on new electrodes and electrochemically characterized in full cells.
Carbon-Nanofibers Encapsulated Metal Oxide Nanocomposite and Its Application as Conversion Anode Material for Lithium Ion Batteries
Authors: Ren Shuhua , Zhao Xiangyu , Chen Ruiyong , Fichtner Maximilian
Published: May 2015

Functional metal oxide/C-fibers composites were synthesized by a simple pyrolysis-oxidation process and have been investigated as promising conversion anode materials for Li-ion batteries. Metallocene was used as precursor and acts as both metal and carbon source. No templates or solvents were involved in the fabrication process. Three different composites of Fe3O4/C, Co3O4/C and CoFe2O4/C were synthesized by applying this method and tentatively studied as active anode materials. The synergistic effects by combining metal oxide nanoparticles and carbon fibers and also their intimate contact developed in the synthetic process are suggested to be crucial for the observed good cycling performance of the composites. This work offers a facile and broadly applicable way for fabrication and utilization of metal oxide/mixed metal oxide-C composites as electrode materials for Li-ion batteries.
Corrosion Mechanism of NiCrWMo Coating Deposited by HVOF
Authors: Achem Calahorra Jamnie Yazmin , Tiburcio Citlalli Gaona , Estupiñan Francisco , Estrada Ariadna Trujillo , Poblano Salas Carlos , Calderón Facundo Almeraya , Cabral Miramontes Jose Angel
Published: May 2015

Coatings Ni-Co-W- Mo have excellent resistance to abrasion and wear, further have good resistance to corrosion in acid and alkaline aqueous media. The thermal spraying technique Oxy-Fuel high speed (Hight Velocity Oxygen-fuel) was used to deposit the coating of the alloy on 304 stainless steel substrates. Such coating was evaluated using electrochemical resistance to linear polarization and curves cyclic polarization in HCl solution, NaOH and distilled water, to compare a function of pH the corrosion resistance and the corrosion mechanism that occurs in this type coatings. The results show that the coating has similar corrosion resistance to the substrate used.
Evaluation of Atmospheric Corrosivity Indexes in the City of Tuxpan Veracruz
Authors: Rosas Pérez Miguel Ángel , Gallardo Castán Ernesto , Lugo Islas Gabriela , Galicia Badillo Aurora , Ramírez Reyes José Luis , García Navarro Norma , Pérez Téllez Juan , Oseguera López J S
Published: May 2015

Faculty of Chemical Sciences in collaboration with the Institute of Engineering of the Universidad Veracruzana has developed a project for the construction of the Corrosivity Map of the State of Veracruz. Among the activities of the project is the evaluation of the indixes of atmospheric corrosivity in the city of Tuxpan Veracruz, due to the industrial, urban activities and to be located in a coastal area, characteristics that influence the corrosion of metallic materials exposed to the atmosphere. A exposition panel was installed with specimens of aluminum wire on steel screws, copper screws and plastic screws to study corrosivity indexes through mass loss in every season of year, and thus classify the different types of atmospheres; marine, industrial and rural-urban according to the values specified in the standard (ISO 8408, 9223, 9224). Corrosivity indexes obtained indicate a domain of rural-urban atmosphere product of excessive urban activities in the region. Expected to detect high levels of marine atmosphere by the presence of chlorides and particles resulting City location front of coast. However, corrosivity indexes for marine atmosphere are within the limit allowed by the normative.
High-Temperature Corrosion of AISI 316L in Chlorosilane Environments at 550°C
Authors: Aller Joshua L , White Preston , Gum Jeffrey , Clark Bryce , Gannon Paul E.
Published: May 2015

High temperature chlorosilane gas streams are used throughout the photovoltaic, polycrystalline silicon, and fumed silica industries as a means to purify, refine, and produce silicon species. These gas streams create a unique corrosion environment due the ability of many metals to form metal-silicides or metal-chlorides depending on the atmosphere. In this study, a method was developed to test AISI 316L stainless steel in a high temperature (550°C) chlorosilane environment by exposing the samples to variable amounts of hydrogen, hydrogen chloride (HCl), and silicon tetrachloride (STC). In this method, the mole fraction of HCl was adjusted to investigate when the transition from silicide formation to chloride formation occurs. Gravimetric and surface analysis was performed before and after exposure, revealing that without any HCl in the system, there was predominately metal silicide formation. As the HCl mole fraction was increased up to about 0.027, there was increasing metal chloride formation and decreasing silicide formation. Above an HCl mole fraction of 0.027, there was predominately chloride formation. The silicide formation was accompanied with a net mass gain due to the relatively low vapor pressure of iron silicide and nickel silicide species. Chloride formation was accompanied with a net mass loss due to the reactive evaporation of iron, nickel, and some chromium with chlorine. Lastly, the implications of this study as they relate to industrial processes are discussed.
Evaluation of Atmospheric Corrosion in the City of Tuxpan Veracruz
Authors: Gallardo Castán Ernesto , Lugo Islas Gabriela , Galicia Badillo Aurora , Ramírez Reyes José Luis , Mercado Bahena Iris Graciela , Alarcón Molina Luis Alexis , García Navarro Norma , Pérez Téllez Juan
Published: May 2015

Tuxpan is a port with economic and industrial important activity, has subject to the process of atmospheric corrosion of metal structures such as boats, ships, oil platforms and Thermoelectric. The main purpose of this paper is to evaluate the Atmospheric Corrosion of Tuxpan Veracruz, it was necessary to install a display panel with carbon steel specimens (Ac -R), galvanized steel (zinc ), aluminum and copper in order to evaluate them in every season by electrochemical methods (electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization curves (CP) and at the end of the year by gravimetric techniques as established by CLIMAT and ISO methodology. The results show the aggressiveness of the marine atmosphere, mainly zinc and carbon steel due to aggressive agents such as chlorides and SiO2 (silica). XRD analysis shows the presence of metal oxides formed on the metal substrate surface.
Transition Metal Foam Electrocatalysts for Hydrogen Evolution Reaction
Authors: Santos Diogo M.F. , Eugenio Sonia , Sequeira Cesar A.C. , Montemor Maria Fátima
Published: May 2015

Nickel (Ni) alloys are low-cost materials with good electrocatalytic activity for the hydrogen evolution reaction (HER) in alkaline water electrolysis. The electrode cost can be further reduced by using alloys with a porous structure, providing high surface area with low catalyst amounts. Herein, transition metal 3D nanoporous foams based on Ni, copper (Cu), and cobalt (Co) alloys are produced over stainless steel substrates. The metallic foams are obtained by galvanostatic electrodeposition using hydrogen bubble evolution as a dynamic template. Their morphology and chemical composition is analyzed by SEM and EDS, respectively. Linear scan voltammetry in 8 M KOH solutions are used to study the HER at the Ni-Cu/Co electrodes at room temperature. Additional chronoamperometry measurements show good stability of the tested foam electrodes. The results suggest that the 3D electrocatalysts can attain high HER efficiencies while using low metal amounts. Moreover, their low-cost, one-step fabrication method presents several advantages over conventional procedures
Electroless Co-B Deposition Using Dimethylamine Borane as Reducing Agent in the Presence of Different Amines
Authors: Stankevičienė Ina , Jagminiene Aldona , Tamasauskaite-Tamasiunaite Loreta , Norkus Eugenijus
Published: May 2015

Cobalt films were deposited by electroless metal plating method on the copper electrode. The effects of pH from neutral to acidic solutions, temperature from 50 to 70 oC and concentration of the reactants on the deposition rate were investigated. The induction period of the electroless deposition reaction depends on solution composition, temperature, and the presence of different amines: diethylenetriamine (dien), triethylenetetraamine (trien), propylenediamine (prop), tetraethylenepentaamine (ttren), pentaethylenehexaamine (pnten).