bluuebunny/crossref_metadata_2025 huggingface dataset:
A case of acute myelogenous leukaemia characterised by the BCR-FGFR1 translocation
Authors: Matikas Alexios , Tzannou Ifigeneia , Oikonomopoulou Dimitra , Bakiri Maria
Published: March 2013

The 8p11 myeloproliferative syndrome is a rare atypical disorder defined by the presence of rearrangements between the fibroblast growth factor receptor 1 (FGFR1) and 1 of 13 partner genes described to date, including the BCR gene on chromosome 22. The disease characterised by the BCR-FGFR1 fusion gene has distinct biological and clinical features, with significant diversity among the published cases. We report a case of BCR-FGFR1 disease which was presented as acute myeloid leukaemia with an aggressive clinical course and we review all the adult cases published in the literature.
Categorising sports injuries in epidemiological studies: the subsequent injury categorisation (SIC) model to address multiple, recurrent and exacerbation of injuries
Authors: Finch Caroline F , Cook Jill
Published: March 2013

Objective

Sports injuries are often recurrent and there is wide recognition that a subsequent injury (of either the same or a different type) can be strongly influenced by a previous injury. Correctly categorising subsequent injuries (multiple, recurrent, exacerbation or new) requires substantial clinical expertise, but there is also considerable value in combining this expertise with more objective statistical criteria. This paper presents a new model, the subsequent injury categorisation (SIC) model, for categorising subsequent sports injuries that takes into account the need to include both acute and overuse injuries and ten different dependency structures between injury types.

Methods

The suitability of the SIC model was demonstrated with date ordered sports injury data from a large injury database from community Australian football players over one playing season. A subsequent injury was defined to have occurred in the subset of players with two or more reported injuries.

Results

282 players sustained 469 subsequent injuries of which 15.6% were coded to categories representing injuries that were directly related to previous index injuries. This demonstrates that players can sustain a number of injuries over one playing season. Many of these will be unrelated to previous injuries but subsequent injuries that are related to previous injury occurrences are not uncommon.

Conclusion

The handling of subsequent sports injuries is a substantial challenge for the sports medicine field—both in terms of injury treatment and in epidemiological research to quantify them. Application of the SIC model allows for multiple different injury types and relationships within players, as well as different index injuries.
High ambulatory blood pressure in male professional football players
Authors: Berge Hilde Moseby , Andersen Thor Einar , Solberg Erik E , Steine Kjetil
Published: March 2013

Background

No data exist on ambulatory blood pressure (ABP) in athletes.

Objectives

To identify ABP and examine recommended follow-up of high office blood pressure (OBP) in male professional football players and secondary study indicators of sympathetic activity.

Methods

Players with high OBP (cases) from a previous screening of 594 players (n=28) were matched for age and ethnicity with players with optimal OBP (controls). High ABP was defined as a mean of ≥135/85 mm Hg during daytime and ≥120/75 mm Hg during night-time. The players replied to questions regarding follow-up of high OBP. High night-time ABP and lack of nocturnal dip (≤10% decline in average BP) were taken as indicators of increased sympathetic activity.

Results

26 cases and 26 controls, mean age 28±4 years, were included. 15 (58%) of the cases had sustained hypertension and 11 (42%) white coat hypertension. Among the controls, 17 (65%) had normotension and 9 (35%) masked hypertension. ABP during night-time was high in 23 (88%) of the cases and in 16 (64%) of the controls, and nocturnal dip was absent in 9 (35%) and 11 (42%), respectively. 10 (38%) of the cases had no follow-up of high OBP.

Conclusions

More than one-third of the players with optimal OBP had masked hypertension during daytime and more than half of all players had high ABP during night-time, which are novel findings in athletes. Together with the reduced nocturnal dip, this might indicate increased sympathetic activity. Follow-up of high OBP after preparticipation screening is random and should be organised.
Survival analysis of HDR brachytherapy versus reoperation versus temozolomide alone: a retrospective cohort analysis of recurrent glioblastoma multiforme
Authors: Archavlis Eleftherios , Tselis Nikolaos , Birn Gerhard , Ulrich Peter , Baltas Dimos , Zamboglou Nikolaos
Published: March 2013

Objectives

Tumour recurrence of glioblastoma multiforme (GBM) after initial treatment with surgical resection, radiotherapy and chemotherapy is an inevitable phenomenon. This retrospective cohort study compared the efficacy of interstitial high dose rate brachytherapy (HDR-BRT), re-resection and sole dose dense temozolomide chemotherapy (ddTMZ) in the treatment of recurrent glioblastoma after initial surgery and radiochemotherapy.

Design

Retropective cohort study.

Setting

Primary level of care with two participating centres. The geographical location was central Germany.

Participants

From January 2005 to December 2010, a total of 111 patients developed recurrent GBM after initial surgery and radiotherapy with concomitant temozolomide. The inclusion criteria were as follows: (1) histology-proven diagnosis of primary GBM (WHO grade 4), (2) primary treatment with resection and radiochemotherapy, and (3) tumour recurrence/progression.

Interventions

This study compared retrospectively the efficacy of interstitial HDR-BRT, re-resection and ddTMZ alone in the treatment of recurrent glioblastoma.

Primary and secondary outcome measures

Median survival, progression free survival and complication rate.

Results

Median survival after salvage therapy of the recurrence was 37, 30 and 26 weeks, respectively. The HDR-BRT group did significantly better than both the reoperation (p<0.05) and the ddTMZ groups (p<0.05). Moderate to severe complications in the HDR-BRT, reoperation and sole chemotherapy groups occurred in 5/50 (10%), 4/36 (11%) and 9/25 (36%) cases, respectively.

Conclusions

CT-guided interstitial HDR-BRT attained higher survival benefits in the management of recurrent glioblastoma after initial surgery and radiotherapy with concurrent temozolomide in comparison with the other treatment modalities. The low risk of complications of the HDR-BRT and the fact that it can be delivered percutaneously in local anaesthesia render it a promissing treatment option for selected patients which should be further evaluated.
A cross-sectional study of visual impairment in elderly population in residential care in the South Indian state of Andhra Pradesh: a cross-sectional study
Authors: Marmamula Srinivas , Ravuri Chandra Sekhar L V , Boon Mei Ying , Khanna Rohit C
Published: March 2013

Objective

To assess the prevalence and major causes of visual impairment (VI) in elderly residents of ‘home for the aged’ institutions in the Prakasam district in India.

Design

Cross-sectional study.

Setting

‘Home for the aged’ institutions in the Prakasam district in the South Indian state of Andhra Pradesh.

Participants

All 524 residents in the 26 ‘homes for aged’ institutions in the district were enumerated.

Primary and secondary outcome measures

Prevalence and causes of VI; visual acuity (VA) was assessed using a Snellen chart at a distance of 6 m. Pinhole VA was assessed if presenting VA was <6/18. Torchlight examination and direct ophthalmoscopy were performed. VI was defined as presenting VA <6/18 in the better eye.

Results

Of the 494 participants examined (response rate 94.3%), 78.1% were women, 72.1% had no formal schooling. The mean age of participants was 70 years (SD ±8.6 years). VI was present in 280/494 individuals (56.9%; 95% CI 52.3 to 61.3). Over 80% of the VI was due to avoidable causes including cataract (57.1%) and uncorrected refractive errors (26.4%). Among 134 individuals who had undergone bilateral cataract surgery, only 78 (58.2%) individuals had presenting VA ≥6/18 and 13/134 (9.7%) participants were blind.

Conclusions

There is high prevalence of VI in the institutionalised elderly population in the Prakasam district in India. A significant proportion of this elderly population with VI can benefit from spectacles and cataract surgery. Strategies are required to provide high-quality services to this population.
Injury among a population based sample of career firefighters in the central USA
Authors: Jahnke Sara A , Poston Walker S Carlos , Haddock Christopher Keith , Jitnarin Nattinee
Published: March 2013

Background

Rates of occupational injuries among firefighters are high because of the physically demanding and variable tasks required by their job. While descriptive data about injuries exist, few studies have explored individual risk factors and their relationship to occupational injury.

Methods

The current study presents data from a population-based sample of 462 career firefighters from 11 randomly-selected fire departments in the Missouri Valley region of the USA (Kansas, Missouri, Iowa, North Dakota, South Dakota, Colorado, Wyoming, Nebraska) who participated in a study evaluating risks for negative cardiovascular outcomes and injury. Relationships were examined between injury and demographic characteristics, body composition, fitness, and health behaviours.

Results

Participants were most likely to be injured during physical exercise and those who reported regular on-duty exercise had a fourfold increase in risk for exercise-related injury compared with those who did not exercise on duty (OR=4.06, 95% CI 1.73 to 12.24). However, those who exercised were half as likely to sustain non-exercise injuries (OR=0.53, 95% CI 0.32 to 0.85).

Conclusions

Findings highlight the benefit of physical training for firefighters despite the risk of injury during exercise.
Factors associated with non-participation in one or two follow-up phases in a cohort study of injured adults
Authors: Langley John Desmond , Lilley Rebbecca , Wilson Suzanne , Derrett Sarah , Samaranayaka Ari , Davie Gabrielle , Ameratunga Shanthi N , Wyeth Emma H , Hansen Paul , Hokowhitu Brendan
Published: March 2013

Objective

To identify factors associated with non-participation at the 12-month and 24-month follow-up phases of a prospective cohort study of injury outcomes.

Methods

Associations between non-participation at follow-up phases and a range of sociodemographic, injury, health, outcome and administrative factors were examined.

Results

An individual's non-participation at 12 months did not necessarily mean non-participation at 24 months. Sociodemographic factors were the most salient for non-participation, regardless of the number of follow-up phases or specific phase considered.

Conclusions

Retention rates in prospective cohort studies of injury outcome may be improved by follow-up of everyone irrespective of previous non-participation, focusing resources to retain men, young adults, indigenous people and those living with people other than family members, and by ensuring that multiple alternative participant contacts are obtained. There is sufficient evidence to be concerned about potential bias given that several of the factors we, and others, have identified as associated with non-participation are also associated with various functional and disability outcomes following injury. This suggests detailed investigations are warranted into the effect non-participation may be having on the estimates for various outcomes.
Historical data decrease complete blood count reflex blood smear review rates without missing patients with acute leukaemia
Authors: Rabizadeh Esther , Pickholtz Itay , Barak Mira , Froom Paul
Published: March 2013

Introduction

The availability of historical data decreases the rate of blood smear review rates in outpatients, but we are unaware of studies done at referral centres. In the following study, we determined the effect of historical data on the rates of peripheral blood smears over a 3-month period and then the detection rate of patients with acute leukaemia.

Methods

All results of complete blood counts (CBCs) tested on three ADVIA 120 analyzers at the regional Rabin Medical Centre, Beilinson Campus over a 3-month period were accessed on a computerised laboratory information system. Over a 3-month period, we determined the proportion of total CBC and patients with criteria for a manual differential count and the actual number of peripheral blood smears done. Finally, we determined the proportion of 100 consecutive patients with acute leukaemia detected using our criteria that included limiting reflex testing according to historical data.

Results

Over the 3-month period, there were 34 827 tests done in 12 785 patients. Without historical data, our smear rate would have been 24.5%, but with the availability of historical data, the blood smear review rate was 5.6%. The detection rate for cases of acute leukaemia was 100%.

Conclusions

We conclude that the availability of previous test results significantly reduces the need for blood smear review without missing any patients with acute leukaemia.
Social participation and drug use in a cohort of Brazilian sex workers
Authors: Leslie Hannah Hogan , Ahern Jennifer , Chinaglia Magda , Kerrigan Deanna , Lippman Sheri A
Published: March 2013

Background

Structural interventions focused on community mobilisation to engender an enabling social context have reduced sexual risk behaviours among sex workers. Interventions to date have increased social participation and shown an association between participation and safer sex. Social participation could modify risk for other health behaviours, particularly drug use. We assessed social participation and drug use before and after implementation of a clinical, social and structural intervention with sex workers intended to prevent sexually transmitted infections/HIV infection.

Methods

We followed 420 sex workers participating in theEncontrosintervention in Corumbá, Brazil, between 2003 and 2005. We estimated the association of participation in external social groups with drug use at baseline and follow-up using logistic regression and marginal modelling. Follow-up analyses of preintervention/postintervention change in drug use employed inverse probability weighting to account for censoring and were stratified by exposure to the intervention.

Results

Social participation showed a protective association with drug use at baseline (1 SD higher level of social participation associated with 3.8% lower prevalence of drug use, 95% CI −0.1 to 8.3). Among individuals exposed toEncontros, higher social participation was associated with an 8.6% lower level of drug use (95% CI 0.1 to 23.3). No significant association was found among the unexposed.

Conclusions

A structural intervention that modified sex workers’ social environment, specifically participation in external social groups, was associated with reduced drug use. These findings suggest that sexual risk prevention initiatives that enhance social integration among marginalised populations can produce broad health impacts, including reductions in drug use.
Protein-energy malnutrition induces an aberrant acute-phase response and modifies the circadian rhythm of core temperature
Authors: Smith Shari E. , Ramos Rafaela Andrade , Refinetti Roberto , Farthing Jonathan P. , Paterson Phyllis G.
Published: March 2013

Protein-energy malnutrition (PEM), present in 12%–19% of stroke patients upon hospital admission, appears to be a detrimental comorbidity factor that impairs functional outcome, but the mechanisms are not fully elucidated. Because ischemic brain injury is highly temperature-sensitive, the objectives of this study were to investigate whether PEM causes sustained changes in temperature that are associated with an inflammatory response. Activity levels were recorded as a possible explanation for the immediate elevation in temperature upon introduction to a low protein diet. Male, Sprague-Dawley rats (7 weeks old) were fed a control diet (18% protein) or a low protein diet (PEM, 2% protein) for either 7 or 28 days. Continuous core temperature recordings from bioelectrical sensor transmitters demonstrated a rapid increase in temperature amplitude, sustained over 28 days, in response to a low protein diet. Daily mean temperature rose transiently by day 2 (p = 0.01), falling to normal by day 4 (p = 0.08), after which mean temperature continually declined as malnutrition progressed. There were no alterations in activity mean (p = 0.3) or amplitude (p = 0.2) that were associated with the early rise in mean temperature. Increased serum alpha-2-macroglobulin (p < 0.001) and decreased serum albumin (p ≤ 0.005) combined with a decrease in serum alpha-1-acid glycoprotein (p < 0.001) suggest an atypical acute-phase response. In contrast, a low protein diet had no effect on the signaling pathway of the pro-inflammatory transcription factor, NFκB, in the hippocampus. In conclusion, PEM induces an aberrant and sustained acute-phase response coupled with long-lasting effects on body temperature.
SPACETIME SINGULARITIES: RECENT DEVELOPMENTS
Authors: UGGLA CLAES
Published: March 2013

Recent developments concerning oscillatory spacelike singularities in general relativity are taking place on two fronts. The first treats generic singularities in spatially homogeneous cosmology, most notably Bianchi types VIII and IX. The second deals with generic oscillatory singularities in inhomogeneous cosmologies, especially those with two commuting spacelike Killing vectors. This paper describes recent progress in these two areas: in the spatially homogeneous case, focus is on mathematically rigorous results, while analytical and numerical results concerning generic behavior and so-called recurring spike formation are the main topics in the inhomogeneous case. Unifying themes are connections between asymptotic behavior, hierarchical structures and solution generating techniques, which provide hints for a link between the nature of generic singularities and a hierarchy of hidden asymptotic symmetries.
STRUCTURE OF INFINITY IN COSMOLOGY
Authors: COTSAKIS SPIROS
Published: March 2013

We discuss recent developments related to certain blow-up methods suitable for the analysis of cosmological singularities and asymptotics. We review results obtained in a variety of currently popular themes and describe ongoing research about universes with various kinds of extreme states, higher-order gravity and certain models of braneworlds.
DIRAC EQUATION FOR EMBEDDED FOUR-GEOMETRIES
Authors: TRZETRZELEWSKI MACIEJ , NORDITA
Published: March 2013

We apply the Dirac's square root idea to constraints for embedded four-geometries swept by a three-dimensional membrane. The resulting Dirac-like equation is then analyzed for general coordinates as well as for the case of a Friedmann–Robertson–Walker (FRW) metric for spatially closed geometries. The problem of the singularity formation at the quantum level is addressed.
PROOF THEORY OF WEAK COMPACTNESS
Authors: ARAI TOSHIYASU
Published: March 2013

We show that the existence of a weakly compact cardinal over the Zermelo–Fraenkel's set theory ZF is proof-theoretically reducible to iterations of Mostowski collapsings and Mahlo operations.
WEINGARTEN CALCULUS FOR MATRIX ENSEMBLES ASSOCIATED WITH COMPACT SYMMETRIC SPACES
Authors: MATSUMOTO SHO
Published: March 2013

A method for computing integrals of polynomial functions on compact symmetric spaces is given. Those integrals are expressed as sums of functions on symmetric groups.
Membrane Fuel Cells - Options for Bipolar Plate Materials and Production Technology
Authors: Heinzel Angelika , Kühnemann Lars , Derieth T. , Grundler M. , Grimm Tobias , Kouachi M.
Published: March 2013

Polymer electrolyte membrane fuel cells PEMFC are the type of fuel cell with the broadest range of possible applications, ranging from power supply to electric drives to small scale grid independent power sources and residential CHP units. The technology has been intensively developed for more than two decades and the remaining R&D tasks focus on life time improvement and cost reduction. The following paper will give results on bipolar plate development for PEMFC.
Development of Thin, Reinforced PEMFC Membranes through Understanding of Structure-Property-Performance Relationships
Authors: Liu Wen , Suzuki Takeyumi , Mao Huiming , Schmiedel Thomas
Published: March 2013

The development of reinforced ultra-thin GORE-SELECT® Membranes with a thickness of 5 µm and below is a demanding process. The present paper discusses an approach in understanding "structure-property-performance" relationships using a variety of analytical techniques that yields fundamental knowledge to aid in the development of high performance fuel cell membranes. The synergy of the methods used is providing information in various length scales from microscopic to macroscopic while analyzing proton conductivity and mechanical responses.
A 3D Two-Phase Model for a Membraneless Fuel Cell Using Decomposition of Hydrogen Peroxide with Y-Shaped Microchannel
Authors: Peng Jie , Zhang Z.Y. , Niu H.T.
Published: March 2013

A three-dimensional, two-phase, multi-component mixture model in conjunction with a finite-volume-based computational fluid dynamics technique is applied to simulate the operation of membraneless fuel cell with Y-shape channel. Hydrogen peroxide is employed both as fuel and oxidant. All transport phenomena occurring in the fuel cell such as fluid flow, mass transfer, electrochemical kinetics and charge transport are considered in this model. The oxygen gas, which is a product in the anode electrode, is assumed to be insoluble. The results show that the presence of gas phase acts to prevent the processes of reactant supply and product removal. Besides, a secondary flow is induced due to the transportation of the gas phase, which drifts from the bottom to the top of the channel and results in serious fuel crossing phenomenon.
Molecular Dynamics Study of Water Transport Property in Micro Hydrophobic Pore
Authors: Fukushima Akinori , Mima Toshiki , Kinefuchi Ikuya , Tokumasu Takashi
Published: March 2013

In this study, the transport property of a water droplet in the nano hydrophobic pore was clarified by molecular dynamics simulation. The size dependence of the transport property of the water droplet in a nano slit pore was focused. Considering several models of the nano pore, the differences of the structures of water droplets were shown and these differences were discussed from the viewpoint of the interaction between hydrophobic walls. Furthermore, forces by the hydrophobic walls were evaluated. From these results, the dependence of the width of the pore and the size of the droplet were clarified. Moreover, the effect of the liquid-vapor interface was considered.
Lattice Boltzmann Modeling of the Effective Thermal Conductivity of an Anisotropic Gas Diffusion Layer in a Polymer Electrolyte Membrane Fuel Cell with Residual Water
Authors: Yablecki Jessica , Hinebaugh James , Bazylak Aimy
Published: March 2013

In the present work, the anisotropic effective thermal conductivity of the gas diffusion layer (GDL) of a polymer electrolyte membrane (PEM) fuel cell is determined using a thermal lattice Boltzmann model. Using saturation patterns obtained from three-dimensional (3-D) pore network modeling simulations with invasion percolation, the thermal conductivity of the GDL containing liquid water is determined. For a GDL modeling domain with a total saturation of 24.4% (flooded inlet condition), increases of 20.8% and 5.4% are noted for the through-plane and in-plane thermal conductivities, respectively. As the GDL plays an important role in thermal and water management within a PEM fuel cell, the simulated thermal conductivities determined in this work can provide insight into the effect of the GDL on the thermal management required for improved PEM fuel cell performance.
Thermo-Fluid Dynamics Simulation of Passive Type PEFC by COMSOL Multipysics
Authors: Nakajima Yasuaki , Ejiri Eiji , Otsuka Junpei
Published: March 2013

The basic three-dimensional computations including heat and mass transport and electrochemical reactions were performed using COMSOL Multiphysics in order to analyze the complicated phenomena occurring in the passive PEFC. Mass transport was calculated with Maxwell-Stephen's equation. Gas was assumed to flow in continuum based on Dulce's law in the gas diffusion layer. It was also assumed the gas flow was laminar in the anode channel and in the cathode half open chamber and that there was no slip on the wall surfaces. A lot of valuable information regarding physical properties, such as local temperature, velocities and mass fractions of gasses and back diffusion were obtained as a result.
Measurements of Water Vapor and Current Distributions and Prediction of Water Crossover in PEMFC under Low-Humidity Conditions
Authors: Nishida Kosuke , Asa Masaya , Tsushima Shohji , Hirai Shuichiro
Published: March 2013

In order to alleviate membrane dryout in proton exchange membrane fuel cells (PEMFCs) under low-humidity conditions, it is necessary to understand water transport between anode and cathode. In this study, the water vapor distribution within the anode gas channel of a low-humidity PEMFC was quantitatively evaluated by using humidity test paper (HTP), and the effects of inlet gas humidification and micro-porous layer (MPL) addition were investigated. In addition, the distribution of the hydrogen flow rate was calculated based on the current distribution measurement, and the local water crossover in the PEM was numerically predicted. It was noted that the MPL addition on the cathode side promotes the back-diffusion of product water at the low-humidity anode inlet of the co-flow serpentine flow field.
Design of a Non-Invasive Optical Fiber Sensor for In Situ Measurement of Temperature in a Proton Exchange Membrane Fuel Cell
Authors: Inman Kristopher , Wang Xia , Sangeorzan Brian
Published: March 2013

Thermal management has been shown to play a key role in all aspects of affecting fuel cell performance including transport of gaseous and liquid species. However, it remains a difficult topic to study due to a lack of experimental techniques which are limited by the PEMFC internal environment and geometry. In this work a non-invasive optical temperature sensor is presented to measure the in situ temperature on the surface of a GDL in a PEMFC based on the principles of phosphor thermometry. The sensor is also demonstrated to be a useful tool for measuring in situ temperature under steady-state and transient operating conditions.
Heterogeneous Porosity Distribution Under Compression of Gas Diffusion Layer Using Synchrotron X-ray Tomography
Authors: Je Junho , Doh Seungwoo , Kim Jongrok , Kim Moo Hwan
Published: March 2013

In this experimental study, we used 3D X-ray tomography with an X-ray microscope (7B2) at the Pohang Light Source to visualize heterogeneous porosity distribution (HPD) according to the gas diffusion layer (GDL) compression ratio in the polymer electrolyte membrane fuel cell (PEMFC). The porosity of the through-plane direction in the carbon fiber type of the GDL is not a single uniform porosity; rather, the porosity has HPD, which is seriously affected by GDL compression. Visualization of HPD of the GDL is very important for understanding and validating the models to predict the effect of GDL compression in the PEMFC. The experimental results show that HPD is more intensified as the GDL compression ratio is increased.
Determination of CL Ionomer Conductivity
Authors: Karan Kunal
Published: March 2013

Proton conduction in the catalyst layer of a polymer electrolyte fuel cell often competes with the diffusion of oxygen and hydrogen in controlling the overall electrochemical performance. The ionomer in the catalyst layer has characteristics thickness in the order of few nanometers, significantly smaller than the thickness of membranes. The porous composite nature of the catalyst layer adds further to the complexity of extracting effective ionic conductivity. This article provides an overview of experimental methods employed for catalyst layer ionic conductivity and thin ionomer film conductivity.
Ice-Crystallization Kinetics and Water Movement in Gas-Diffusion and Catalyst Layers
Authors: Dursch Thomas J. , Ciontea Monica A. , Trigub Gregory J. , Radke Clayton J. , Weber Adam Z.
Published: March 2013

Under subfreezing conditions, ice forms in the gas-diffusion (GDL) and catalyst layers (CL) of proton-exchange-membrane fuel cells (PEMFCs), drastically reducing cell performance. Although a number of strategies exist to prevent ice formation, there is little fundamental understanding of ice-crystallization mechanisms and kinetics within PEMFC components. We use differential scanning calorimetry (DSC) to measure ice-crystallization kinetics in both the GDL and CL. Nonlinear ice-crystallization rate expressions are developed from a convolution integral over nucleation and growth rates, following Johnson-Mehl-Avrami-Kolmogorov theory. Quantitative agreement is found with the DSC data. Validated rate expressions are now available for predicting ice-crystallization kinetics within both GDL and CL components of PEMFCs.
The Effect of Microporous Layer on PEFC Dryout
Authors: Malevich Dzmitry , Halliop Ela , Suryana Jaka , Peppley Brant A. , Pharoah Jon G. , Karan Kunal
Published: March 2013

Transients in the resistances of membranes and catalyst layers were investigated, using electrochemical impedance spectroscopy, during the dryout of a PEFC fed with H2 and N2. Two types of cells, with and without a MPL on the N2 fed electrode, were studied. It was demonstrated that transients in membrane and catalyst layer resistance occur concurrently. Results suggest that the presence of a MPL does not introduce changes in water distribution profile in the membrane-electrode assembly during cell dryout.
Investigation of Water Breakthrough and Flow in Gas Diffusion Layers and Relavance to Fuel Cell Water Management
Authors: Lu Zijie , Patterson Joseph
Published: March 2013

Water breakthrough pressures for three gas diffusion layers (GDLs): SGL 25BC, SGL 25BA, and SGL 25AA, were measured ex-situ at a water injection rate corresponding to 2.0 A/cm2 over temperature range of 20 °C to 70 °C. SEM imaging and estimates of breakthrough pressure by a "slit" capillary model indicate the dominate water breakthrough locations in SGL 25BC is via cracks in the microporous layer. The breakthrough pressures for SGL 25BA and SGL 25AA were estimated by a "doughnut" shaped-pore capillary model. The breakthrough pressure dramatically decreased with increasing temperature for the three GDLs; however, estimates of breakthrough pressure via the Laplace equation reveal that the capillarity cannot completely account for this temperature influence. Estimates for the fraction of the GDL void volume needed for water flow showed that water flows in less than 0.1% of the void volume.
Subzero Degradation Analysis of Membrane Electrode Assemblies Modified with Additives
Authors: Pistono Antonio , Rice Cynthia Ann , Lewis Jacob , Ramani Vijay K.
Published: March 2013

Baseline results for a direct sprayed membrane electrode assembly (MEA) are presented over the course of subzero isothermal water fill tests. The MEA exhibited very little degradation as measured by current step sweeps using 4 different oxidizing gasses. MEAs with additives have been prepared to address the issue of water storage in the cathode catalyst layer and ionic conductivity of the catalyst layer at subzero conditions.
PEMFC GDE Oxygen Mass Transport Coefficient Separation with Different Gas Diluents
Authors: Reshetenko Tatyana V. , St-Pierre Jean
Published: March 2013

A parametric current distribution model is proposed for the overall PEMFC reactant mass transfer coefficient determination. The model was derived for a dilute reactant stream and a low cell voltage (limiting current). Separation of the mass transfer coefficient into gas and ionomer phase components is achieved with similar current distribution measurements completed with different molecular mass diluents. An extrapolation to a diluent with zero molecular mass leads to the ionomer phase mass transfer coefficient. The gas phase mass transfer coefficient is subsequently calculated using an additive relationship between the overall mass transfer coefficient and its components (gas and ionomer phase coefficients). Experimental measurements demonstrate the validity of the current distribution model and emphasize the need to use dilute reactant streams to facilitate data treatment.
Liquid Water Scavenging of PEMFC Contaminants
Authors: Wetton Brian , St-Pierre Jean
Published: March 2013

Models were derived for the scavenging effect of product liquid water on airborne proton exchange membrane fuel cell (PEMFC) contaminants. A time scale analysis of contaminant mass transfer processes, product water accumulation in the gas diffusion electrode, and dissociation reactions indicated that the contaminant saturates the product liquid water simplifying model derivation. The baseline model only accounts for contaminant solubility and shows a large effect for ethylene glycol. An extension to this model was derived for the presence of contaminant dissociation reactions within the product liquid water using SO2 as a model contaminant. The extended model demonstrates the large impact of dissociation reactions at low SO2 concentrations. For both models, explicit expressions for the average gas phase contaminant concentration within the fuel cell were also derived and can be used as a surrogate for the effective contaminant concentration to correlate the fuel cell performance loss and facilitate the definition of tolerance limits and filtering equipment.
Internal Currents, CO2 Emissions and Decrease of the Pt Electrochemical Surface Area during Fuel Cell Start-Up and Shut-Down
Authors: Dillet Jérôme , Lamibrac Adrien , Maranzana Gaël , Durst Julien , Spernjak Dusan , Fairweather Joseph D , Mukundan Rangachary , Borup Rodney L. , Didierjean Sophie , Lottin Olivier
Published: March 2013

This work explores the links between internal currents measured during fuel cell start-up (SU) and shut-down (SD) and the CO2 emissions in the cathode exhaust gases associated with the oxidation of the electrode carbon support. The total charge exchanged between the active and passive regions of a cell appears to be a function of the common residence time of air (or nitrogen) and hydrogen in the anode compartment during SU/SD operation. Both the CO2 emissions and the charges exchanged between the active and passive regions of the cell increase with this residence time. However, the complete oxidation of carbon to CO2 does not seem to be the main contribution to the reverse currents.
Flow Field Design for a Polymer Electrolyte Unitized Reversible Fuel Cell
Authors: Hwang Chulmin , Ito Hiroshi , Maeda Tetsuhiko , Nakano Akihiro , Kato Atsushi , Yoshida Tetsuya
Published: March 2013

Unitized reversible fuel cells (URFC) combine the functionality of a fuel cell and electrolyzer in one unitized device. Proper water management in URFC is critical to achieve better performance. The flow channel design is directly related to this water management because supplied and discharged water through the flow channels of bipolar plates is essential for not only fuel cell operation but also electrolysis operation. The purpose of this research was to find out an effective flow field design. An experimental testing has been conducted to investigate the effects of different flow field design (parallel, serpentine-single, and serpentine-dual) to the URFC performance. And bare Ti-felt GDL and PTFE treated (10wt.% emulsion) Ti-felt GDL are tested in the oxygen electrode of URFC. The polarization curve has been obtained and it is analyzed. The experimental result shows that the parallel and serpentine-dual flow types provide the better fuel cell performance and electrolysis performance when they are consist with PTFE treated Ti-felt GDL, whereas serpentine-single shows fuel cell performance degradation even though water electrolysis performance is improved.
Development of a High Performance MEA Using Current-Sensing Atomic Force Microscopy (CS-AFM) and Nano-Scale Impedance Spectroscopy (NIS)
Authors: Kwon O Sung , Lee Sang Cheol , Lee Dong Ha , Han Byungchan , Hwang Sun-Wook , Choi Gyeungho , Mukherjee Santanu , Bates Alex , Park Sam
Published: March 2013

Current-sensing Atomic Force Microscopy (CS-AFM) and Nano-scale Impedance Spectroscopy (NIS) are key characterization tools in the research and development of diverse materials systems. These have been used in fuel cell research to distinguish between various sources of cell losses; for example, ohmic losses in the electrodes and electrolytes, activation over-potentials due to reaction kinetics, and mass transport effects. Proton transport and water diffusion phenomena are locally observed to determine the ionic channel structure and mechanism.
Advances in Proton Exchange Membrane Technology
Authors: Banerjee Shoibal , Prugh David N. , Frisk Simon
Published: March 2013

Significant advances in low humidity and high temperature operation of proton exchange membrane fuel cells have been achieved by using a novel polymeric composite membrane based on Nafion® perfluorosulfonic acid (PFSA) copolymer. A fundamental understanding of the microstructure of currently used ePTFE reinforced Nafion® perfluorosulfonic acid (PFSA) copolymer and how the microstructure limits the high temperature and low humidity performance is discussed. Fuel cell performance data and mechanical stability data of the new composite membrane are also presented in this paper.
Challenges to High-Volume Production of Fuel Cell Materials: Quality Control
Authors: Ulsh Michael , Sopori Bhushan , Aieta Niccolo V. , Bender Guido
Published: March 2013

As fuel cells become more prominent, new manufacturing and production methods are needed to enable increased volumes with high quality. One necessary component of this industrial growth will be the accurate measurement of the variability of a wide range of material properties during the manufacturing process. Three different quality measurement techniques for fuel cell membranes and membrane-containing assemblies are described. The techniques have been demonstrated to detect as-manufactured and simulated defects at substrate motion rates comparable to current industrial production rates for these materials.
Effect of Thermal Treatment on the Properties of Ultra-Thin Nafion Film
Authors: Paul Devproshad K , Karan Kunal
Published: March 2013

Recently, we reported results for ultra-thin Nafion films ranging 4 nm - 300 nm self-assembled on SiO2 terminated silicon surface. Very distinct wettability for these films were noted; thinner films (<100 nm) exhibited hydrophilic type behavior whereas thicker (>100 nm) films showed hydrophobic surface nature. In this study, we report on the effect of annealing (at 146 oC for 1 hour) on film properties. Water contact angle measurement showed that thinner films turned into hydrophobic resulting similar contact angle to thicker film. This phenomenon indicated that significant surface rearrangement of thinner film happened during annealing period. Moreover, phase contrast correspond to the hydrophilicity/hydrophobicity gave a distinguishable surface properties of unannealed vs annealed and thinner vs thicker films.
Accelerated Testing of Carbon Corrosion and Membrane Degradation in PEM Fuel Cells
Authors: Mukundan Rangachary , James Greg , Ayotte Dana , Davey John R. , Langlois David , Spernjak Dusan , Torraco Dennis , Balasubramanian Sivagaminathan , Weber Adam Z. , More Karren L. , Borup Rodney L.
Published: March 2013

Accelerated Stress Tests (ASTs) to characterize carbon corrosion were performed on MEAs based on 3 different carbon supports. High surface area carbon exhibited the best initial performance but the fastest degradation rate. On the other hand, highly graphitized carbon exhibiting the slowest degradation rate but had the lowest initial performance. TEM analysis of the MEAs after corrosion indicated Pt particle size growth in all the catalyst layers in addition to significant thinning of the high surface area carbon-based catalyst layers. Voltage loss breakdown identified mass transport losses resulting from a compaction of the catalyst layer porosity as the greatest contributor to performance loss. Three different membrane ASTs were performed on 2 distinct MEAs (designated P5 and HD6) from Ballard Power Systems and the degradation compared to that observed in the field. The membrane chemical degradation AST resulted in significant membrane thinning not observed in the field. The membrane mechanical degradation AST was able to reproduce the degradation phenomenon observed in the field but had little ability to distinguish between various membranes. A combined mechanical/chemical AST was examined to better simulate the degradation rates observed in the field.
Ionic Conductivity of [dema][TfO]/Solid Acid-Base Composite Membrane
Authors: Fujisawa Ai , Matsuzawa Koichi , Kohno Yuji , Mitsushima Shigenori
Published: March 2013

Solid acids or bases are expected to improve an ionic conductivity and mechanical properties of the novel proton conductive electrolyte using diethylmethylammonium trifuluoromethane-sulfonate ([dema][TfO]) of a room temperature molten salt (RTMS). In our previous study, SiO2 as a solid acid and MgO as a solid base have positive interaction with [dema][TfO] for the ionic conductivity. In this study, the effect of SiO2 or MgO addition into the ion gel membrane which is the mixture of a polymer and the RTMS on the ionic conductivity has been investigated. The results show that addition of a solid acid or base to the membrane improves compression strength, wettability of the RTMS and mechanical properties. Moreover, the SiO2 complex membrane improve the ionic conductivity because of the positive interaction at SiO2 /[dema][TfO] interfaces.
Sulfonated-Nanocomposites Incorporated Polybenzimidazole Based Polymer Electrolyte Membranes for Fuel Cells
Authors: Stewart Kerrilee Ayel , Pal Singh Missan Harinder
Published: March 2013

Polybenzimidazole based PEMs have become an important part of research into medium and high temperature PEMFCs. In order for this membrane to function at a high capacity, it must however be impregnated with a strong acid to increase its proton conductivity. The addition of this acid into the polymer leads to a decrease in mechanical stability of the polymer. An alternate way of circumventing this problem is through the incorporation of acid-functionalized titania nanocomposites. As such acid functionalized nanotubular material was incorporated into the ABPBI polymer matrix and the properties of the membrane were studied. IEC valued showed a marked increase in the availability of ions for transport in functionalized nanocomposites over unfunctionalised nanocomposites and lead to an increase in the conductivity by one order. Morphological as well as electrical, thermal and mechanical properties of these membranes were studied.
Polymer Inorganic Composite (PIC) Nanofiber Proton Exchange Membrane for Direct Methanol Fuel Cells (DMFC)
Authors: Arumugam Ganesh Kumar , Kamavaram Venkat , Veedu Vinod , Cheung Ken
Published: March 2013

Performance limitations of the state of art NafionTM membranes affects the overall power output of DMFCs. To overcome the issues in Nafion membranes, Oceanit designed, developed and tested a polymer inorganic composite membrane for use in DMFC using high concentration methanol. Experimental details and fuel cell performance is presented in this manuscript.
Ammonium Polyphosphate Composite Based Electrolytes for Intermediate Temperature Fuel Cells
Authors: Kluy Norbert , Reeb Berthold B.L. , Paschos Odysseas , Maglia Filippo , Angioni Simone , Righetti Pierpaolo P. , Schneider Oliver , Stimming Ulrich
Published: March 2013

Composite materials consisting of Ammonium Polyphosphate (APP), SiO2 and TiO2 were prepared and embedded in a polymer matrix to obtain proton conductive membranes. The membranes were characterized by scanning electron microscopy and impedance techniques. First results show that the conductivity increases with the amount of APP composite material inside the membrane, while the mechanical properties are dominated by the matrix material. Membranes with a large portion of APP composites show the same conductivity as bulk APP composite material.
3D-Graphitized and Iron Modified Carbon Aerogels for Sustainable Energy Applications
Authors: Kolla Praveen , Kerce Kimberly , Normah Yahaya , Houk Joseph , Rhine Wendell , Dixon David , Zhao Yong , Fong Hao , Smirnova Alevtina
Published: March 2013

3D-carbon aerogel nanomatrix has been modified with iron nitrate in the amounts of 10 and 20 wt. % by wet incipient method. The crystal structure, morphology, and electrocatalytic activity of the formed nanocomposites have been studied in comparison to the unmodified carbon aerogels after their heat-treatment at 900oC, 1200oC and 1400oC in argon. The mass and specific surface area losses in these materials reduced with iron doping is clear from BET isotherms and BJH pore size analysis. The HRTEM analysis confirms the presence of uniformly distributed ~43.5nm iron nanoparticles surrounded by graphite layers. The XRD analysis show that the level of graphitization increases with the sintering temperature and the concentration of the iron-containing phase. The ORR electrocatalytic activity studies demonstrate the influence of the heat-treatment temperature of samples on the ORR activity. Temperature programed reduction is carried out to understand the reduction behavior of these catalysts to metallic iron, to use them as substrates for direct CNT growth.
Nanofiber Electrodes for High Power PEM Fuel Cells
Authors: Brodt Matthew , Wycisk Ryszard , Pintauro Peter N.
Published: March 2013

Very high power was produced from membrane-electrode-assemblies (MEAs) with a Nafion 212 membrane and an electrospun nanofiber cathode that were prepared with Johnson-Matthey (JM) HiSpec{trade mark} 4000 catalyst. At a cathode Pt loading of 0.064 mg/cm2, the maximum power density for H2/air fuel cell operation at 80oC and ambient pressure was 538 mW/cm2. Fuel cell operation at two temperatures (60{degree sign}C and 80 {degree sign}C), backpressures up to 2.0 atmospheres, and a variety of gas feed flow rates was investigated. An electrospun cathode with a Pt loading of 0.055 mg/cm2 produced a maximum power density of 906 mW/cm2 at 80{degree sign}C, 2000 sccm fully humidified air, and a backpressure of 2 atm.
Durability of the Electrocatalyst Fabricated based on Carbon Nanotubes
Authors: Fujigaya Tsuyohiko , Berber Mohamed Reda , Nakashima Naotoshi
Published: March 2013

We describe the fabrication of a well-defined carbon nanotubes (CNTs)-based composite, in which the CNTs are individually wrapped by a polymer in homogeneous fashion and platinum nanoparticles (Pt) are immobilized on the polymer-wrapped CNTs. Polybenzimidazoles (PBIs) are used for the wrapping polymer since a strong adsorption of PBIs onto the CNT surfaces enables the exfoliation of CNT bundles and nanometer-thick PBI wrapping layer serves as a glue for the efficient immobilization of Pt. We demonstrate the use of the composite for the polymer electrolyte fuel cell (PEFC) electrocatalyst after acid doping. Single cell tests reveal that the ultra-thin PBI-wrapping layer around the CNTs serves as a proton conducting layer to deliver protons in the catalyst membrane. PEFCs using the composite show an excellent fuel cell performance at 120 oC under non-humid atmosphere, whereas the conventional Nafion-based PEFCs are not workable in such condition. Durability of the electrocatalyst was studied.