bluuebunny/crossref_metadata_2025 huggingface dataset:
Is Ankle Contracture After Stroke Due to Abnormal Intermuscular Force Transmission?
Authors: Diong Joanna , Herbert Robert D.
Published: September 2014

Contracture after stroke could be due to abnormal mechanical interactions between muscles. This study examined if ankle plantarflexor muscle contracture after stroke is due to abnormal force transmission between the gastrocnemius and soleus muscles. Muscle fascicle lengths were measured from ultrasound images of soleus muscles in five subjects with stroke and ankle contracture and six able-bodied subjects. Changes in soleus fascicle length or pennation during passive knee extension at fixed ankle angle were assumed to indicate intermuscular force transmission. Changes in soleus fascicle length or pennation were adjusted for changes in ankle motion. Subjects with stroke had significant ankle contracture. After adjustment for ankle motion, 9 of 11 subjects demonstrated small changes in soleus fascicle length with knee extension, suggestive of intermuscular force transmission. However, the small changes in fascicle length may have been artifacts caused by movement of the ultrasound transducers. There were no systematic differences in change in fascicle length (median between-group difference adjusting for ankle motion = -0.01, 95% CI -0.26–0.08 mm/degree of knee extension) or pennation (-0.05, 95% CI -0.15–0.07 degree/degree of knee extension). This suggests ankle contractures after stroke were not due to abnormal (systematically increased or decreased) intermuscular force transmission between the gastrocnemius and soleus.
The Effects of Orthotic Intervention on Multisegment Foot Kinematics and Plantar Fascia Strain in Recreational Runners
Authors: Sinclair J. , Isherwood J. , Taylor P.J.
Published: September 2014

Chronic injuries are a common complaint in recreational runners. Foot orthoses have been shown to be effective for the treatment of running injuries but their mechanical effects are still not well understood. This study aims to examine the influence of orthotic intervention on multisegment foot kinematics and plantar fascia strain during running. Fifteen male participants ran at 4.0 m·s−1 with and without orthotics. Multisegment foot kinematics and plantar fascia strain were obtained during the stance phase and contrasted using paired t tests. Relative coronal plane range of motion of the midfoot relative to the rearfoot was significantly reduced with orthotics (1.0°) compared to without (2.2°). Similarly, relative transverse plane range of motion was significantly lower with orthotics (1.1°) compared to without (1.8°). Plantar fascia strain did not differ significantly between orthotic (7.1) and nonorthotic (7.1) conditions. This study shows that although orthotics did not serve to reduce plantar fascia strain, they are able to mediate reductions in coronal and transverse plane rotations of the midfoot.
Partial inhibition of gp130-Jak-Stat3 signaling prevents Wnt–β-catenin–mediated intestinal tumor growth and regeneration
Authors: Phesse Toby J. , Buchert Michael , Stuart Emma , Flanagan Dustin J. , Faux Maree , Afshar-Sterle Shoukat , Walker Francesca , Zhang Hui-Hua , Nowell Cameron J. , Jorissen Robert , Tan Chin Wee , Hirokawa Yumiko , Eissmann Moritz F. , Poh Ashleigh R. , Malaterre Jordane , Pearson Helen B. , Kirsch David G. , Provero Paolo , Poli Valeria , Ramsay Robert G. , Sieber Oliver , Burgess Antony W. , Huszar Dennis , Vincan Elizabeth , Ernst Matthias
Published: September 2014

Partial suppression of the inflammatory gp130-Jak-Stat pathway inhibits intestinal tumor growth.
Differentiation Rates Regulate Pool Sizes
Authors: Hines Pamela J.
Published: September 2014

Embryonic chick and mouse reveal how neural tube differentiation takes on new strategies as development progresses.
Personalized Heart Healing
Authors: LaMarco Kelly
Published: September 2014

The decrease of function in the
ALDH2*2
genotype disrupts a cardioprotective oxidative stress regulatory circuit.
Daily Dance of Synaptic Partners
Authors: VanHook Annalisa M.
Published: September 2014

The number of synapses and the identities of synaptic partners change over the course of a day in circadian pacemaker neurons.
Pharmacokinetics and Pharmacodynamics of (+)-Primaquine and (−)-Primaquine Enantiomers in Rhesus Macaques (Macaca mulatta)
Authors: Saunders David , Vanachayangkul Pattaraporn , Imerbsin Rawiwan , Khemawoot Phisit , Siripokasupkul Raveewan , Tekwani Babu L. , Sampath Aruna , Nanayakkara N. P. Dhammika , Ohrt Colin , Lanteri Charlotte , Gettyacamin Montip , Teja-Isavadharm Paktiya , Walker Larry
Published: September 2014

Primaquine (PQ) remains the sole available drug to prevent relapse of
Plasmodium vivax
malaria more than 60 years after licensure. While this drug was administered as a racemic mixture, prior studies suggested a pharmacodynamic advantage based on differential antirelapse activity and/or toxicities of its enantiomers. Oral primaquine enantiomers prepared using a novel, easily scalable method were given for 7 days to healthy rhesus macaques in a dose-rising fashion to evaluate their effects on the blood, liver, and kidneys. The enantiomers were then administered to
Plasmodium cynomolgi
-infected rhesus macaques at doses of 1.3 and 0.6 mg/kg of body weight/day in combination with chloroquine. The (−)-PQ enantiomer had higher clearance and apparent volume of distribution than did (+)-PQ and was more extensively converted to the carboxy metabolite. There is evidence for differential oxidative stress with a concentration-dependent rise in methemoglobin (MetHgb) with increasing doses of (+)-PQ greater than that seen for (−)-PQ. There was a marked, reversible hepatotoxicity in 2 of 3 animals dosed with (−)-PQ at 4.5 mg/kg. (−)-PQ in combination with chloroquine was successful in preventing
P. cynomolgi
disease relapse at doses of 0.6 and 1.3 mg/kg/day, while 1 of 2 animals receiving (+)-PQ at 0.6 mg/kg/day relapsed. While (−)-PQ was also associated with hepatotoxicity at higher doses as seen previously, this has not been identified as a clinical concern in humans during >60 years of use. Limited evidence for increased MetHgb generation with the (+) form in the rhesus macaque model suggests that it may be possible to improve the therapeutic window for hematologic toxicity in the clinic by separating primaquine into its enantiomers.
Inhibition of Rift Valley Fever Virus Replication and Perturbation of Nucleocapsid-RNA Interactions by Suramin
Authors: Ellenbecker Mary , Lanchy Jean-Marc , Lodmell J. Stephen
Published: September 2014

Rift Valley fever virus (RVFV) is an emerging infectious pathogen that causes severe disease in humans and livestock and has the potential for global spread. There are currently no proven safe and effective treatment options for RVFV infection. Inhibition of RNA binding to RVFV nucleocapsid protein (N) represents an attractive antiviral therapeutic strategy because several essential steps in the RVFV replication cycle involve N binding to viral RNA. In this study, we demonstrate the therapeutic potential of the drug suramin by showing that it functions well as an inhibitor of RVFV replication at multiple stages in human cell culture. Suramin has been used previously to treat trypanosomiasis in Africa. We characterize the dynamic and cooperative nature of N-RNA binding interactions and the dissociation of high-molecular-mass ribonucleoprotein complexes using suramin, which we previously identified as an N-RNA binding inhibitor in a high-throughput screen. Finally, we elucidate the molecular mechanism used by suramin
in vitro
to disrupt both specific and nonspecific binding events important for ribonucleoprotein formation.
Spectrum of Activity and Mechanisms of Resistance of Various Nucleoside Derivatives against Gammaherpesviruses
Authors: Coen Natacha , Duraffour Sophie , Topalis Dimitri , Snoeck Robert , Andrei Graciela
Published: September 2014

The susceptibilities of gammaherpesviruses, including Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), and animal rhadinoviruses, to various nucleoside analogs was investigated in this work. Besides examining the antiviral activities and modes of action of antivirals currently marketed for the treatment of alpha- and/or betaherpesvirus infections (including acyclovir, ganciclovir, penciclovir, foscarnet, and brivudin), we also investigated the structure-activity relationship of various 5-substituted uridine and cytidine molecules. The antiviral efficacy of nucleoside derivatives bearing substitutions at the 5 position was decreased if the bromovinyl was replaced by chlorovinyl. 1-β-
d
-Arabinofuranosyl-(
E
)-5-(2-bromovinyl)uracil (BVaraU), a nucleoside with an arabinose configuration of the sugar ring, exhibited no inhibitory effect against rhadinoviruses but was active against EBV. On the other hand, the fluoroarabinose cytidine analog 2′-fluoro-5-iodo-aracytosine (FIAC) showed high selectivity indices against gammaherpesviruses that were comparable to those of brivudin. Additionally, we selected brivudin- and acyclovir-resistant rhadinoviruses
in vitro
and characterized them by phenotypic and genotypic (i.e., sequencing of the viral thymidine kinase, protein kinase, and DNA polymerase) analysis. Here, we reveal key amino acids in these enzymes that play an important role in substrate recognition. Our data on drug susceptibility profiles of the different animal gammaherpesvirus mutants highlighted cross-resistance patterns and indicated that pyrimidine nucleoside derivatives are phosphorylated by the viral thymidine kinase and purine nucleosides are preferentially activated by the gammaherpesvirus protein kinase.
New Insights into Chloramphenicol Biosynthesis in Streptomyces venezuelae ATCC 10712
Authors: Fernández-Martínez Lorena T. , Borsetto Chiara , Gomez-Escribano Juan Pablo , Bibb Maureen J. , Al-Bassam Mahmoud M. , Chandra Govind , Bibb Mervyn J.
Published: September 2014

Comparative genome analysis revealed seven uncharacterized genes,
sven0909
to
sven0915
, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (
sven0916–sven0928
) of
Streptomyces venezuelae
strain ATCC 10712 that was absent in a closely related
Streptomyces
strain that does not produce chloramphenicol. Transcriptional analysis suggested that three of these genes might be involved in chloramphenicol production, a prediction confirmed by the construction of deletion mutants. These three genes encode a cluster-associated transcriptional activator (Sven0913), a phosphopantetheinyl transferase (Sven0914), and a Na
+
/H
+
antiporter (Sven0915). Bioinformatic analysis also revealed the presence of a previously undetected gene,
sven0925
, embedded within the chloramphenicol biosynthetic gene cluster that appears to encode an acyl carrier protein, bringing the number of new genes likely to be involved in chloramphenicol production to four. Microarray experiments and synteny comparisons also suggest that
sven0929
is part of the biosynthetic gene cluster. This has allowed us to propose an updated and revised version of the chloramphenicol biosynthetic pathway.
Salmonella enterica Serovar Enteritidis Antimicrobial Peptide Resistance Genes Aid in Defense against Chicken Innate Immunity, Fecal Shedding, and Egg Deposition
Authors: McKelvey Jessica A. , Yang Ming , Jiang Yanhua , Zhang Shuping
Published: September 2014

Salmonella enterica
serovar Enteritidis (
S
. Enteritidis) is a major etiologic agent of nontyphoid salmonellosis in the United States.
S
. Enteritidis persistently and silently colonizes the intestinal and reproductive tract of laying hens, resulting in contaminated poultry products. The consumption of contaminated poultry products has been identified as a significant risk factor for human salmonellosis. To understand the mechanisms
S
. Enteritidis utilizes to colonize and persist in laying hens, we used selective capture of transcribed sequences to identify genes overexpressed in the HD11 chicken macrophage cell line and in primary chicken oviduct epithelial cells. From the 15 genes found to be overexpressed in both cell types, we characterized the antimicrobial peptide resistance (AMPR) genes,
virK
and
ybjX
,
in vitro
and
in vivo. In vitro
, AMPR genes were required for natural morphology, motility, secretion, defense against detergents such as EDTA and bile salts, and resistance to antimicrobial peptides polymyxin B and avian β-defensins. From this, we inferred the AMPR genes play a role in outer membrane stability and/or modulation. In the intestinal tract, AMPR genes were involved in early intestinal colonization and fecal shedding. In the reproductive tract,
virK
was required in early colonization whereas a deletion of
ybjX
caused prolonged ovary colonization and egg deposition. Data from the present study indicate that AMPR genes are differentially utilized in various host environments, which may ultimately assist
S
. Enteritidis in persistent and silent colonization of chickens.
Strain-Dependent Cellular Immune Responses in Cattle following Escherichia coli O157:H7 Colonization
Authors: Corbishley Alexander , Ahmad Nur Indah , Hughes Kirsty , Hutchings Michael R. , McAteer Sean P. , Connelley Timothy K. , Brown Helen , Gally David L. , McNeilly Tom N.
Published: September 2014

Enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 causes hemorrhagic diarrhea and potentially fatal renal failure in humans. Ruminants are considered to be the primary reservoir for human infection. Vaccines that reduce shedding in cattle are only partially protective, and their underlying protective mechanisms are unknown. Studies investigating the response of cattle to colonization generally focus on humoral immunity, leaving the role of cellular immunity unclear. To inform future vaccine development, we studied the cellular immune responses of cattle during EHEC O157:H7 colonization. Calves were challenged either with a phage type 21/28 (PT21/28) strain possessing the Shiga toxin 2a (Stx2a) and Stx2c genes or with a PT32 strain possessing the Stx2c gene only. T-helper cell-associated transcripts at the terminal rectum were analyzed by reverse transcription-quantitative PCR (RT-qPCR). Induction of gamma interferon (IFN-γ) and T-bet was observed with peak expression of both genes at 7 days in PT32-challenged calves, while upregulation was delayed, peaking at 21 days, in PT21/28-challenged calves. Cells isolated from gastrointestinal lymph nodes demonstrated antigen-specific proliferation and IFN-γ release in response to type III secreted proteins (T3SPs); however, responsiveness was suppressed in cells isolated from PT32-challenged calves. Lymph node cells showed increased expression of the proliferation marker Ki67 in CD4
+
T cells from PT21/28-challenged calves, NK cells from PT32-challenged calves, and CD8
+
and γδ T cells from both PT21/28- and PT32-challenged calves following
ex vivo
restimulation with T3SPs. This study demonstrates that cattle mount cellular immune responses during colonization with EHEC O157:H7, the temporality of which is strain dependent, with further evidence of strain-specific immunomodulation.
A Novel Transcriptional Activator,
tubX
, Is Required for the Stability of Bacillus sphaericus Mosquitocidal Plasmid pBsph
Authors: Ge Yong , Zhao Ni , Hu Xiaomin , Shi Tingyu , Cai Quanxin , Yuan Zhiming
Published: September 2014

Stable maintenance of the low-copy-number plasmid pBsph in
Bacillus sphaericus
requires a partitioning (
par
) system that consists of a filament-forming protein,
B. sphaericus
TubZ (TubZ-Bs); a centromere-binding protein, TubR-Bs; and a centromere-like DNA site,
tubC
, composed of three blocks (I, II, and III) of 12-bp degenerate repeats. Previous studies have shown that mini-pBsph replicons encoding the TubZ system are segregationally highly unstable, whereas the native pBsph is stably maintained. However, the mechanism underlying the stability discrepancy between pBsph and its minireplicon is poorly understood. Here
orf187
(encoding TubX), a gene downstream of
tubZ
-Bs, was found to play a role in plasmid stabilization. Null mutation or overexpression of
tubX
resulted in a defect in pBsph stability and a significant decrease in the level of
tubRZ
-Bs expression, and the TubX-null phenotype was suppressed by ectopic expression of a wild-type copy of
tubX
and additional
tubRZ
-Bs. An electrophoresis mobility shift assay (EMSA) and a DNase I footprinting assay revealed that the TubX protein bound directly to five 8-bp degenerate repeats located in the
par
promoter region and that TubX competed with TubR-Bs for binding to the
par
promoter. Further studies demonstrated that TubX significantly stimulated the transcription of the
par
operon in the absence of
tubR
-Bs, and a higher level of gene activation was observed when
tubR
-Bs was present. These results suggested that TubX positively regulates
tubRZ
-Bs transcription by interfering with TubR-Bs-mediated repression and binding directly to the
tubRZ
-Bs promoter region.
A novel approach to compare pinniped populations across a broad geographic range
Authors: Sweeney Kathryn L. , Shertzer Kyle W. , Fritz Lowell W. , Read Andrew J.
Published: September 2014

We utilized aerial images and employed photogrammetric methodologies to collect standardized lengths of Steller sea lions (Eumetopias jubatus) terrestrially hauled out. We conducted comparisons among all site types and separately for rookery and haulout site-types between the two distinct population segments (DPSs; eastern and western) and two broad regions within the western DPS experiencing contrasting population abundance trends. An observed adult female index was created from measurements of reproductive females — in the presence of a pup or juvenile — and was applied as a model constraint for “adult females”. We fitted a finite mixture distribution model to the length-frequency data to estimate the proportion population for three delineated age–sex classes (juveniles, adult females, and adult males) and mean length for juveniles and adult males. Estimated proportions reflected what we expected; however, the broad region within the western DPS exhibiting substantial population declines had greater proportion of all age–sex classes on rookery sites than increasing broad region. Adult sea lions were significantly shorter in the eastern DPS than the western area, providing further evidence of morphological differences between the DPSs. We also introduce a less resource-demanding method for estimating population demographics, and potentially vital rates, for pinnipeds across a vast geographic range.
Review of recent results on charm mixing and CP violation
Authors: Polycarpo Érica , dos Reis Alberto C.
Published: September 2014

The establishment of [Formula: see text] mixing in 2007 generated a renaissance of interest in charm physics. The field gained even more strength with the commissioning of the LHC, which opened a new era of high sensitivity measurements. In this paper, we briefly review the basic formalism and experimental techniques related to charm mixing and to CP violation searches in D-meson decays and then report on recent experimental results obtained by the B-factories, CDF and LHCb.
Abelian p-form (p = 1, 2, 3) gauge theories as the field theoretic models for the Hodge theory
Authors: Kumar R. , Krishna S. , Shukla A. , Malik R. P.
Published: September 2014

Taking the simple examples of an Abelian 1-form gauge theory in two (1+1)-dimensions, a 2-form gauge theory in four (3+1)-dimensions and a 3-form gauge theory in six (5+1)-dimensions of space–time, we establish that such gauge theories respect, in addition to the gauge symmetry transformations that are generated by the first-class constraints of the theory, additional continuous symmetry transformations. We christen the latter symmetry transformations as the dual-gauge transformations. We generalize the above gauge and dual-gauge transformations to obtain the proper (anti-)BRST and (anti-)dual-BRST transformations for the Abelian 3-form gauge theory within the framework of BRST formalism. We concisely mention such symmetries for the 2D free Abelian 1-form and 4D free Abelian 2-form gauge theories and briefly discuss their topological aspects in our present endeavor. We conjecture that any arbitrary Abelian p-form gauge theory would respect the above cited additional symmetry in D = 2p(p = 1, 2, 3, …) dimensions of space–time. By exploiting the above inputs, we establish that the Abelian 3-form gauge theory, in six (5+1)-dimensions of space–time, is a perfect model for the Hodge theory whose discrete and continuous symmetry transformations provide the physical realizations of all aspects of the de Rham cohomological operators of differential geometry. As far as the physical utility of the above nilpotent symmetries is concerned, we demonstrate that the 2D Abelian 1-form gauge theory is a perfect model of a new class of topological theory and 4D Abelian 2-form as well as 6D Abelian 3-form gauge theories are the field theoretic models for the quasi-topological field theory.
Fermions in the 5D gravity-scalar standing wave braneworld
Authors: Gogberashvili Merab , Midodashvili Pavle
Published: September 2014

In this paper, we investigate localization problem for spinor fields within the (5D) standing wave braneworld with the bulk real scalar field and show that there exist normalizable fermion field zero modes on the brane.
Classification of singular spinor fields and other mass dimension one fermions
Authors: Cavalcanti R. T.
Published: September 2014

In this paper, we investigate the constraint equations of the Lounesto spinor fields classification and show that it can be used to completely characterize all the singular classes, which can potentially accommodate further mass dimension one fermions, beyond the well known Elko spinor fields. This result can be useful for two purposes: Besides a great abridgement in the classification of a given spinor field, we provide a general form of each class of spinor fields, which can be used furthermore to search for a general classification of spinors dynamics.
DEPENDENCE OF ENDOCYTOSIS CAUSED BY DEPLETION EFFECTS ON THE ASPECT RATIO OF COLLOIDAL PARTICLE
Authors: ZENG YAN , LIU YANHUI , CHEN YINGBING , MAO WEI , HU LIN , MAO ZONGLIANG , SONG XIAOYI , XU HOUQIANG
Published: September 2014

In colloidal suspensions containing large and small particles, a peculiar attractive force caused by entropy appears, this force can cause aggregation of large particles. With the concentration of small particles increasing, the large particles can be endocytosed by vesicle. A continuum model is developed to investigate the equilibrium mechanics between a biomembrane and an enveloped colloidal particle with different aspect ratios. The results show that the endocytosis of colloidal particle depends on the aspect ratio of colloidal particle. For a spherical colloidal particle (aspect ratio is zero), the entropy provides sufficient favorable energy to drive its engulfment; however, at a high aspect ratio, the entropy is not sufficient to overcome the resistance from the biomembrane and causes endocytosis.
A 3D COUPLED MATHEMATICAL MODEL FOR THE GROWTH OF AVASCULAR SOLID TUMOR
Authors: ZHAO NING , IRAMINA KEIJI , CHEN XIAN
Published: September 2014

We develop a coupled mathematical model of avascular tumor growth based on porous media mechanics. This comprises of the migration of tumor cells (TCs), the degradation of extracellular matrix (ECM), the transport of matrix-degrading enzymes (MDEs), the seepage of tissue fluid and the supplement and consumption of oxygen. The simulation that a solid tumor grows in the micro-environment composed of the pre-existing capillaries and the surrounding tissues, and the specific property of varying porosity with the growth of TCs in a tumor micro-environment are taken into account. We propose functional coefficients for fluid seepage and oxygen diffusion, and incorporate the convection–diffusion of oxygen and the convection of MDEs. From this modified model the main findings include: first, a solid tumor originating in the inlet region undergoes necrosis in the outlet region because of a low supply of oxygen, while a solid tumor originating in the outlet region undergoes necrosis at the primary site because of overconsumption of oxygen; second, tumors further from capillaries grow faster than tumors close to adjacent capillaries; third, the pre-existing capillaries cause some impact to the transport of those chemical factors involved in tumor growth, and further affect tumor migration and necrosis.
3D structure and evolution of folds during normal fault dip linkage
Authors: Rotevatn Atle , Jackson Christopher A.-L.
Published: September 2014

Understanding the 3D geometry and evolution of extension-related folds is important because they may document the geometry and evolution of the associated faults, influence sediment routing and accommodation development, and may represent targets for hydrocarbon exploration or CO
2
storage. Previous work on extension-related folds has largely been restricted to a 2D plane of observation; in this study we use 3D seismic reflection data from the Gulf of Suez, Egypt to determine the 3D geometry and evolution of fault-parallel folds during dip linkage of a vertically segmented extensional fault array that is locally decoupled across a salt-bearing interval. The 3D geometry of individual faults in the array and adjacent hanging-wall folds varies along strike; rollover structures occur above listric faults, whereas fault-bend folds occur above faults that have a ramp–flat–ramp geometry. Quantitative analysis of fault–fold attributes (e.g. fold amplitude) and the growth history of the fault array indicate that fault shape is controlled by the style of dip linkage, which in turn is controlled by the lateral separation of sub- and supra-salt segments prior to linkage. Small lateral separation yields a relatively subtle change in the overall convexity of the listric fault, whereas larger lateral separation results in a ramp–flat–ramp fault geometry, with the layer-parallel detachment lying within the salt. This study provides a link between fault spacing, style of dip linkage, final fault shape and, ultimately, the style of hanging-wall folding in mechanically layered stratigraphy. Our study indicates that 3D seismic reflection data have the ability to provide us with new 3D insights into the variability of, and controls on, the geometry and evolution of fault-related folds.
New tools and approaches in carbonate reservoir quality prediction: a case history from the Shu'aiba Formation, Saudi Arabia
Authors: Cantrell D. L. , Griffiths C. M. , Hughes G. W.
Published: September 2014

Reservoir quality prediction has historically been the ‘holy grail’ of reservoir geologists, yet few have succeeded at achieving this in a quantitative fashion. This study presents a new approach to pre-drill reservoir quality prediction that involves the integration of a variety of modelling techniques to understand, quantify and predict the geological processes that control reservoir quality. Since the initial reservoir quality framework is established at the time of deposition by a variety of depositional controls, this approach uses numerical process models to predict initial reservoir quality; results from these depositional models are then modified via a series of process modelling technologies to quantify and predict post-depositional modifications that have significantly affected reservoir quality in the interval of interest. This approach is illustrated using an example from the Early Cretaceous Shu'aiba Formation in eastern Saudi Arabia, where depositional facies, diagenesis and resulting reservoir quality are predicted and tested against well and seismic data, with generally positive results. Model-predicted sediment thicknesses match thicknesses measured in wells to within ±0.5%; depositional facies and diagenetic trends seen in key wells from the Shaybah field matched model-predicted facies and diagenesis; and model-predicted porosity matched observed porosity within ±1.8 porosity units.
A Novel Tyrosinase Base Biosensor for the Quantification of Antioxidant Capacity: Evaluation on Infusions of Medicinal Plants
Authors: Rodríguez-Sevilla Erika , Ramirez-Silva Maria Teresa , Palomar-Pardavé Manuel , Romero-Romo Mario , Marty Jean Louis , Ibarra-Escutia Pedro
Published: September 2014

The working electrode of a screen-printed-type electrodes, SPE, was modified with Tyrosinase enzyme (Tyr) using different immobilization method namely: entrapment, using polyvynil alcohol, PVA, cross-linking using glutaraldehyde, GA, and cross-linking using GA and Human Serum Albumin, HSA, the resulting electrodes were named as SPE/Tyr/PVA, SPE/Tyr/GA and SPE/Tyr/HSA/GA respectively. All these biosensors were characterized from amperometry and EIS thechniques. From the amperimetric evaluation the apparent Michaelis-Menten constant, Km´, of each biosensor were evaluated and from the impedance measurements the respective charge transfer resistance, Rct
, were assessed. It was found that the biosensor SPE/Tyr/GA has the lowest Km´(57±7)mM and Rct
values, the lowest detection and quantification limits for catechol quantification notwithstanding, the highest sensitivity corresponds to others biosensor. Using the SPE/Tyr/GA biosensor, the Trolox Equivalent Antioxidant Capacity (TEAC) was determined for infusions prepared with Mirto (Salvia microphylla), Hierba dulce (Lippia dulcis) and Salve Real (Lippia alba); medicinal plants commonly used in Mexico.
Trace Detection of 2, 4, 6-Trinitrotoluene Using Electrochemical Gas Sensors
Authors: Sekhar Praveen K. , Zhou Jie , Hamblin E. R. , Brosha Eric L.
Published: September 2014

In this article, selective and sensitive detection of trace amounts of 2, 4, 6-trinitrotoluene (TNT) is demonstrated. The screening system is based on a sampling/concentrator front end and electrochemical potentiometric gas sensors as the detector. Preferential hydrocarbon and nitrogen oxide(s) mixed potential sensors with integrated heaters were used to capture the signature of the explosive. Quantitative measurements based on hydrocarbon and nitrogen oxide sensor responses indicated that the detector sensitivity scaled proportionally with the mass of the explosives (down to 250 ng). The sensitivity was found to increase with increasing flow rate.
A Study of SOFC Cathode Degradation in H2O Environments
Authors: Pellegrinelli Christopher , Huang Yi-Lin , Taillon Joshua A. , Salamanca-Riba Lourdes G. , Wachsman Eric D.
Published: September 2014

An understanding of degradation mechanisms of SOFC cathodes under operating conditions is essential for the development of commercial, intermediate temperature (<700°C) SOFCs. Literature shows that the presence of H2O in the cathode impacts the performance of SOFCs. In this study, we attempt to determine the degradation mechanisms of the composite cathode, (La0.8Sr0.2)0.95MnO3±δ - (Y2O3)0.8(ZrO2)0.92 (LSM-YSZ) in an H2O environment based on a multi-faceted approach. LSM-YSZ/YSZ/LSM-YSZ symmetric cells were examined in the presence of the contaminant (H2O) under different cycling, polarization and working conditions. Symmetric cell performance was measured by in-situ electrochemical impedance spectrometry (EIS), and directly compared to quantitative microstructural parameters obtained from FIB-SEM 3D reconstructions. FIB-SEM is a powerful technique to quantify important performance characteristics such as triple phase boundary (TPB) length and surface to volume ratio. EIS and FIB-SEM results were compared to kinetic rate data, extracted from isotope exchange experiments, to determine mechanistic relationships.
Mechanical and Electrical Properties of Ceramic Electrodes for Solid Oxide Fuel Cells
Authors: Gore Colin M. , Hussain A. Mohammed , Yoon Hee Sung , Blackburn Bryan M. , Wachsman Eric D.
Published: September 2014

The benefits of porous ceramic scaffolds as supporting electrodes, particularly anodes, for solid oxide fuel cells (SOFCs) have been previously demonstrated. The effects of electrode material and microstructure on the mechanical and electrical properties of these porous ceramic scaffolds are investigated in this study. Electrode strength is evaluated by three-point-bend tests and compared with four-point probe measurements of electrical conductivity to yield a greater understanding of the tradeoffs between materials, porosity, and performance of SOFC anodes consisting of porous gadolinia- doped ceria (GDC) or yttria-stabilized zirconia (YSZ) infiltrated with Co, Cu, or Ni metal. We revealed that the initial strength and electrical conductivity of electrode components do not necessarily correlate to properties of the final electrode due to several physical effects.
Advanced 3D Imaging and Analysis of SOFC Electrodes
Authors: Tariq Farid , Yufit Vladimir , Kishimoto Masashi , Cui Guansen , Somalu Mahendra , Brandon Nigel P.
Published: September 2014

Tomographic techniques allow for the 3D imaging andchracterisation of complex microstructures down towards tens of nanometers; which are inadequately described in 2D. The performance of the SOFCs is dependent on nano/micro-structure as the electrochemical reactions and transport phenomena are strongly affected by the complex porous microstructure, where important reactions occur. Furthermore, during processing or operation microstructural evolution may degrade electrochemical performance. Here we use tomographic techniques to probe the 3D electrode structure at micro-nanometer length scales. Subsequently, micro/nano structural changes are followed to facilitate understanding the differences which occur with shape, structures and morphology at high resolution. Additionally the quantification of electronic, ionic and gas interfaces are also correlated with observed differences in electrode behaviour. When coupled with experiments and mechanical computational models, the results show nano/microstructural and compositional variations can significantly affect performance of SOFC electrodes. Altogether this provides important insights for electrode design and understanding sources of performance degradation.
Towards the Microstructural Optimization of SOFC Electrodes Using Nano Particle Infiltration
Authors: Kishimoto Masashi , Lomberg Marina , Ruiz-Trejo Enrique , Brandon Nigel P.
Published: September 2014

A one-dimensional numerical model of a nickel-infiltrated gadolinium-doped ceria (Ni-GDC) electrode is developed to investigate the effect of the microstructural parameters on the electrode performance. The real electrode microstructure information is obtained with focused ion beam tomography and useful microstructural parameters such as tortuosity factor, surface information and particle/pore sizes are quantified. These are used to estimate the effective transport coefficients and the electrochemical reaction rate in the electrode. The overpotential characteristics obtained from the developed model have a quantitative agreement with the experimental results. The sensitivity analysis reveals that the performance of the examined electrode is rate-determined by the electrochemical reaction on the GDC-pore contact surface, and therefore the increase of the contact surface by decreasing the characteristic length scale down to submicron scale is effective to enhance the electrode performance.
Effects of Current Collector Positions on Temperature and Reactive Current Distributions in a Micro-Tubular Solid Oxide Electrolysis Cell
Authors: Mizusawa Tatsuya , Araki Takuto
Published: September 2014

A two-dimensional tubular model of a Ni+YSZ electrode supported micro-tubular solid oxide electrolysis cell (SOEC) was developed to clarify its temperature distribution on high temperature steam electrolysis. The entropy change of SOEC is endothermic and the temperature distribution is more complex than that of SOFCs. In addition, in the micro-tubular SOEC, large bias of reaction distributions can be occurred by current collecting position, and it will lead further complicated thermal transport phenomena and big thermal distributions. Therefore, in this model, heat, mass, electric charge transport and electrochemical reaction were calculated simultaneously. The overpotential and the temeprature change were validated by experimental i-V curves and temperature changes of micro-tubular SOEC. The numerical results suggest that effects of current collector position were not small and cannot be ignored in micro-tubular SOEC operation.
(Plenary) Pore Network Modeling of the Full Membrane Electrode Assembly of a Polymer Electrolyte Membrane Fuel Cell
Authors: Aghighi Mahmoudreza , Gostick Jeff T.
Published: September 2014

Pore network modeling was applied to a full PEM membrane electrode assembly sandwich. This model included liquid water percolation and gas transport in the gas diffusion and catalyst layers, and ionic transport in the catalyst layers and membrane. The ability of pore network models to resolve discrete water clusters played a key role in the electrochemical simulations. It was found that local water blockages not only cause concentration polarization, but also that the protons generated in the anode must travel longer paths to reach an active site on the cathode not masked by a discrete water. Consequently, the iR polarization was actually increased in the presence of liquid water. This behavior is not typically observed in continuum models since they do not treat water treated as explicit blockages and hence do not see the increased transport lengths resulting from the localized production and consumption of protons.
(Plenary) Substrate Effects on the Activity and Stability of Nanoparticulated Electrocatalysts for the H2/O2 Fuel Cell Reactions
Authors: Ferreira Orlando L. S. , Martins Pedro F. B. D. , Biancolli Ana L. G. , Hassan Ayaz , Sato André G. , Ticianelli Edson A.
Published: September 2014

Among the hydrogen fuelled systems, the proton exchange membrane (PEM) and the alkaline (AFC) fuel cells appear as most adequate candidates for applications in automotive, portable or stationary devices. However, significant efforts still have to be done regarding the limitations introduced by the slow oxygen reduction reaction (ORR) kinetics and the poisoning of the anode by CO or other contaminants, particularly when the hydrogen is produced by the reforming or dehydrogenation of other fuels. In this work, the performance and stability of platinum-based catalysts supported on carbon with or without tungsten or molybdenum carbides/oxides were investigated for the oxygen reduction reaction (ORR) in acid and alkaline electrolytes and hydrogen oxidation reaction (HOR) in the presence of CO in PEM single cells.
Dissolution of Platinum Single Crystal Surfaces under Potential Cycling in Sulfuric Acid Solution
Authors: Sugawara Yu , Sasaki Mayu , Muto Izumi , Hara Nobuyoshi
Published: September 2014

The dissolution of Pt(100), Pt(110), and Pt(111) single crystal surfaces under potential cycling conditions in 0.5 M H2SO4 solution was investigated by electrochemical measurements, ICP-MS analyses, and EC-STM observations. Pt(111) surface had higher corrosion resistance than Pt(100) and Pt(110) during potential cycles in 0.5 M H2SO4 solution, and hardly dissolved in the potential range below 1.2 V. EC-STM observations revealed the step structures became straight in the Pt(100) surface and the roughness in Pt(111) terraces gradually increases by the potential cycling in the range of 0.5 – 1.4 V. The formation of Pt islands with a higher surface energy by the potential cycling brought the increase of Pt dissolution rate in the Pt(111) surface with the number of cycle.
Nickel Nanowire Oxidation and Its Effect on Platinum Galvanic Displacement and Methanol Oxidation
Authors: Alia Shaun M , Pylypenko Svitlana , Neyerlin K.C. , Kocha Shyam S , Pivovar Bryan S
Published: September 2014

The heat treatment of nickel (Ni) nanowires (NiNWs) in oxygen is examined for its effect on platinum (Pt) galvanic displacement and the activity of Pt-coated NiNWs (PtNiNWs) in the methanol oxidation reaction (MOR). Annealing of NiNWs in oxygen is found to reduce Pt displacement and increase the resistance of surface Ni to potential-driven dissolution (during electrochemical break-in). By reducing Ni dissolution, oxophilic species are provided in close proximity to Pt sites and the MOR activity of PtNiNWs improves, particularly at low overpotential in rotating disk electrode half-cells.
Can CO-Tolerant Anodes be Economically Viable for PEMFC Applications with Reformates?
Authors: Wang Jia X. , He Ping , Zhang Yu , Ye Siyu
Published: September 2014

Several years ago, the answer to this question was negative based on the criteria for an anode with <0.1 mg cm-2 of platinum group metals to perform similarly without and with 50 ppm CO in hydrogen proton exchange membrane fuel cells (PEMFCs). Now, with the amount of CO impurities reduced to 10 ppm in reformates, a <1% performance loss with a 1.5% air-bleed has become a reasonable target. The CO-tolerant catalyst also needs to be dissolution resistant up to 0.93 V, viz., the potential experienced at the anode during startup and shutdown of the fuel cells. We recently demonstrated our ability to simultaneously enhance activity and stability by using single crystalline Ru@Pt core-shell nanocatalysts. Here, we report that the performance target with reformates was met using bilayer-thick Ru@Pt core-shell nanocatalysts with 0.047 mg cm-2 Pt and 0.024 mg cm-2 Ru loading, supporting a positive prognosis for the economically viable use of reformates in PEMFC applications.
Development of MEAs with Pt/Mesoporous Carbon as a Cathode Catalyst
Authors: Minamida Yasuto , Noda Zhiyun , Hayashi Akari , Sasaki Kazunari
Published: September 2014

With the aim of developing durable electrocatalysts for polymer electrolyte fuel cells, we have been working on Mesoporous Carbon (MC), composed by a nano-channel structure with the diameter of ca.10 nm. Based on the increased stability of metal particles on the curved surface comparing to the flat surface, Pt particles are encapsulated into the pores of MC and used as an electrocatalyst (Pt/MC). In this study, membrane-electrode-assemblies were developed with Pt/MC as a cathode catalyst. Their durability on the current-voltage response was evaluated using the potential cycle test at the potential range where the dissolution and re-precipitation of Pt particles occurs. As a result, increased durability has been demonstrated most likely because of reducing Pt mobility on the carbon support. Successful Nafion® introduction into nano-cahnnels of MC comes to a key factor to further increase both performance and durability.
Effect of Nanostructure of the Electrocatalyst Based on Carbon Nanotube for the Activation Overpotential for PEFC
Authors: Nagashima Akiyo , Fujigaya Tsuyohiko , Nakashima Naotoshi
Published: September 2014

Polymer electrolyte fuel cell (PEFC) using liquid phosphoric acid (PA) as polymer electrolyte membrane has poor durability, due to leaching of PA from the membrane, which causes the deterioration of PEFC performance during long-term operation. To overcome this issue, poly(vinylphosphonic acid) (PVPA) was used for electrolyte instead of PA. Although this PEFC showed high durability, this catalyst had large overpotential in the area of low current density, probably due to the poisoning of Pt by PVPA coating. In this study, we explored the new preparation method to avoid the Pt poisoning and investigated the catalytic performance by electrochemical techniques.
2D Platinum Network ORR Catalyst on Carbon and Niobium Oxide Hybrid Support
Authors: Xu Chunchuan , Yang Jun , Pence Benjamin , Gath Kerrie , Pietrasz Patrick , Sulek Mark , Sun Kai , Sohm Evan , Meng Guangnan
Published: September 2014

A two dimensional (2D) platinum network catalyst on graphitic carbon and amorphous NbOx hybrid support has been synthesized by the Arc Plasma Deposition (APD) method. The 2D platinum structure on the conductive, corrosion resistant amorphous metal oxide significantly increases the catalyst stability under RDE accelerated stress tests. RDE and 5cm2 MEA single cell test results show that the catalyst has higher specific and mass activities than those of conventionally prepared platinum on graphitic carbon (Pt/GC) catalyst. The microstructures of the catalyst were characterized by scanning tunneling microscopy (STM).
Understanding the Growth of Pt Nanoparticles by Galvanic Displacement on ITO Nanocubes for ORR
Authors: Liu Ying , Zhao Shuai , Mustain William E
Published: September 2014

A statistical approach was taken to understand the nucleation and growth of Pt nanoparticles by galvanic displacement on tin-doped indium oxide. A modified Poisson distribution function was able to not only describe the Pt growth, it also provided insight into the nature of the surface atoms present, which allowed the model to accurately predict the mass and specific oxygen reduction activities for Pt/ITO with increased loading.
Correlation between Preparation Condition and Performance of Pt/SnO2/KB for Cathode Catalyst of PEMFC
Authors: Kinumoto Taro , Kitayama Sawaka , Matsuoka Miki , Tsumura Tomoki , Toyoda Masahiro
Published: September 2014

Pt/SnO2/KB-x was prepared as the novel cathode catalyst having higher durability as well as higher catalytic activity for PEMFCs (proton exchange membrane fuel cells). This catalyst was prepared via. decoration of Ketjen black with SnO2 nanoparticles and following Pt loading and then was finally made heat-treatment. In particular, in this study, correlation between the finally heat-treatment temperature and the catalytic performance, in terms of the durability and the activity for ORR (oxygen reduction reaction) is investigated. The activity for ORR in terms of the specific activity is not strongly depended on the heat-treatment temperature; on the other hand, the durability given in the ECA (electrochemical surface area) of Pt particles reaches maximum among the Pt/SnO2/KB-x (120 < x < 300).
Improvement of the Electrocatalytic Activity of Zirconium Oxide-Based Catalyst for ORR
Authors: Okada Yohei , Ishihara Akimitsu , Arao Masazumi , Matsumoto Masashi , Imai Hideto , Kohno Yuji , Matsuzawa Koichi , Mitsushima Shigenori , Ota Ken-ichiro
Published: September 2014

Development of non-platinum electrocatalyst for oxygen reduction reaction (ORR) is required for real commercialization of polymer electrolyte fuel cells. We focused on group 4 and 5 transition metal oxides, because they have high chemical stability under acidic atmosphere even in high potential region, and are less expensive than platinum. In this study, we prepared zirconium oxide based electrocatalysts prepared by the oxidation of oxy-zirconium phthalocyanine in low oxygen pressure and tried to disperse the starting material on carbon support to improve the ORR activity. It was revealed that the use of tetrahydrofuran (THF) as a solvent with impregnation method was more effective to obtain the large ORR current density than that of N-methylpyrrolidone (NMP). This is because the production of fine secondary particles using tetrahydrofuran (THF) as a solvent.
Enhancement of Oxygen Reduction Activity of Titanium Nano-Oxide-Based Electrocatalysts for PEFC Cathode
Authors: Hayashi Tomoaki , Ishihara Akimitsu , Matsumoto Masashi , Imai Hideto , Kohno Yuji , Matsuzawa Koichi , Mitsushima Shigenori , Ota Ken-ichiro
Published: September 2014

Development of non-platinum electrocatalyst for oxygen reduction reaction (ORR) is required for commercialization of polymer electrolyte fuel cells. We focused on titanium, which is inexpensive and has large amount of resources. Recently, we found that titanium oxide-based compounds made from titanium-organic complexes with oxidation under low oxygen partial pressure had high ORR activity. In this study, we prepared titanium oxide-based ORR catalysts (Ti-CNOs) by conducting ball-mills in dry process or impregnation method with N-methylpyrrolidone as a solvent. We found that the Ti-CNOs prepared by ball-milling in dry process showed high rest potential and large ORR current density. The highest rest potential of the ORR on the Ti-CNOs was over 1.0 V vs. RHE, indicating that titanium oxide-based catalysts are promising as an alternative ORR catalyst.