bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratigraphic architecture of a tide‐influenced shelf‐edge delta, Upper Cretaceous Dorotea Formation, Magallanes‐Austral Basin, Patagonia
Authors: Schwartz Theresa M. , Graham Stephan A.
Published: October 2014

The Magallanes‐Austral Basin of Patagonian Chile and Argentina is a retroforeland basin associated with Late Cretaceous–Neogene uplift of the southern Andes. The Upper Cretaceous Dorotea Formation records the final phase of deposition in the Late Cretaceous foredeep, marked by southward progradation of a shelf‐edge delta and slope. In the Ultima Esperanza district of Chile, laterally extensive, depositional dip‐oriented exposures of the Dorotea Formation contain upper slope, delta‐front and delta plain facies. Marginal and shallow marine deposits include abundant indicators of tidal activity including inclined heterolithic stratification, heterolithic to sandy tidal bundles, bidirectional palaeocurrent indicators, flaser/wavy/lenticular bedding, heterolithic tidal flat deposits and a relatively low‐diversity Skolithos ichnofacies assemblage in delta plain facies. This work documents the stratigraphic architecture and evolution of the shelf‐edge delta that was significantly influenced by strong tidal activity. Sediment was delivered to a large slump scar on the shelf‐edge by a basin‐axial fluvial system, where it was significantly reworked and redistributed by tides. A network of tidally modified mouth bars and tidal channels comprised the outermost reaches of the delta complex, which constituted the staging area and initiation point for gravity flows that dominated the slope and deeper basin. The extent of tidal influence on the Dorotea delta also has important implications for Magallanes‐Austral Basin palaeogeography. Prior studies establish axial foreland palaeodrainage, long‐term southward palaeotransport directions and large‐scale topographic confinement within the foredeep throughout Late Cretaceous time. Abundant tidal features in Dorotea Formation strata further suggest that the Magallanes‐Austral Basin was significantly embayed. This ‘Magallanes embayment’ was formed by an impinging fold–thrust belt to the west and a broad forebulge region to the east.
Sex differences in nutritional status of HIV‐exposed children in Rwanda: a longitudinal study
Authors: Condo Jeanine U. , Gage Anastasia , Mock Nancy , Rice Janet , Greiner Ted
Published: October 2014

Objective

To examine sex differences in nutritional status in relation to feeding practices over time in a cohort of HIV‐exposed children participating in a complementary feeding programme in Rwanda.

Methods

We applied a longitudinal design with three measurements 2–3 months apart among infants participating in a complementary feeding programme who were 6–12 months old at baseline. Using early feeding practices and a composite infant and child feeding index (ICFI) as indicators of dietary patterns, we conducted a multivariate analysis using a cross‐sectional time series to assess sex differences in nutritional status and to determine whether there was a link to discrepancies in dietary patterns.

Results

Among 222 boys and 258 girls, the mean (±SD) Z‐score of stunting, wasting and underweight was −2.01 (±1.59), −0.15 (±1.46), −1.19 (±1.29) for boys; for girls they were −1.46 (±1.56), 0.22 (±1.29), −0.63 (±1.19); all sex differences in all three indicators were statistically significant (P < 0.001). However, there were only minor differences in early feeding practices and none in the ICFI by sex.

Conclusions

HIV‐exposed male children may be at higher risk of malnutrition in low‐resource setting countries than their female counterparts. However, at least in a setting where complementary foods are being provided, explanations may lie outside the sphere of dietary patterns.
How do we treat life‐threatening anemia in a Jehovah's Witness patient?
Authors: Posluszny Joseph A. , Napolitano Lena M.
Published: October 2014

The refusal of allogeneic human blood and blood products by Jehovah's Witness (JW) patients complicates the treatment of life‐threatening anemia. For JW patients, when hemoglobin (Hb) levels decrease beyond traditional transfusion thresholds (<7 g/dL), alternative methods to allogeneic blood transfusion can be utilized to augment erythropoiesis and restore endogenous Hb levels. The use of erythropoietin‐stimulating agents and intravenous iron has been shown to restore red blood cell and Hb levels in JW patients, although these effects may be significantly delayed. When JW patients have evidence of life‐threatening anemia (Hb <5 g/dL), oxygen‐carrying capacity can be supplemented with the administration of Hb‐based oxygen carriers (HBOCs). Although HBOCs are not Food and Drug Administration (FDA) approved, they may be obtained and administered with FDA, institutional review board, and patient approval. We describe a protocol‐based algorithm to the management of life‐threatening anemia in JW patients and review time to anemia reversal and patient outcomes using this approach.
Incidence and molecular basis of CD36 deficiency in Shanghai population
Authors: Li Ruishu , Qiao Zhenglei , Ling Bing , Lu Ping , Zhu Ziyan
Published: October 2014

Background

CD36 is a multifunctional membrane receptor and is expressed in several cell lines. Individuals who lack platelet (PLT) CD36 are at risk for immunization against this antigen, leading to several clinical syndromes. This study aimed to investigate the frequency and molecular basis of CD36 deficiency in Shanghai.

Study Design and Methods

Whole blood samples were collected from healthy blood donors, and the PLTs and monocytes were analyzed using flow cytometry to determine CD36 deficiency type. After genomic DNA was extracted, Exons 3 to 14 of CD36 gene including a part of relevant flanking introns were amplified. Direct nucleotide sequencing and sequence alignment were performed. The samples that showed mutations were confirmed by clonal sequencing.

Results

Of the 1022 healthy blood donors analyzed, 22 individuals failed to express CD36 on PLTs; two of them expressed no CD36 on their monocytes either. These results demonstrated that the frequencies of Type I (lacking CD36 expression on PLTs and monocytes) and Type II (lacking CD36 expression on PLTs only) CD36 deficiency among the study population were 0.2 and 2.0%, respectively. Nucleotide sequencing analysis revealed nine different mutations including six mutations that were not yet reported. The most frequent mutations among the study population were 329‐330delAC and 1228‐1239delATTGTGCCTATT.

Conclusion

The study findings have confirmed the fact that the frequency of CD36 deficiency in the Chinese population is slightly lower than that in other Asian countries. The identification of several new mutation types indicated the polymorphism of CD36 gene in the Shanghai population.
Liberalisation and Protection under Overlapping Free Trade Agreements: Dynamic Interplay between Free Trade Agreements and Investment
Authors: Postigo Antonio
Published: October 2014

Two decades into the most recent wave of regionalism many of its implications remain to be fully understood. A vast literature has explored the impacts of free trade agreements (FTAs) on investment flows, but less attention has been given to how existing patterns of investment alter FTA liberalisation. It is contended here that the dynamic interplay between overlapping FTA areas and the investment sunk in them shapes governments' and firms' positions regarding further FTA liberalisation. During trade negotiations, a country may decide to exclude a sector from FTA liberalisation to prevent (concession prevention) future FTA partners from making similar demands. Concession prevention could also occur when a foreign firm, holding a dominant market position in a host country, relinquishes liberalisation demands in an FTA between host and home countries to prevent its current position being eroded if the host country grants similar (or better) concessions to competing firms from other countries in future FTAs. Conversely, investment sunk into a country's sensitive sector in the territory of partners from previous FTAs could pre‐empt (concession pre‐emption) the protectionist position of that country when it subsequently negotiates FTAs with the investment‐source countries. These arguments were tested in the negotiations around the liberalisation of the automotive industry that Thailand and Malaysia had with Japan in their respective bilateral FTAs. The distinct interaction between investment and the FTAs in which these countries participate resulted either in entrenchment of protectionism in the sector or its liberalisation across subsequent FTAs.
Estimating the residual risk for HIV, HCV and HBV in different types of platelet concentrates in Germany
Authors: an der Heiden M. , Ritter S. , Hamouda O. , Offergeld R.
Published: October 2014

Background and Objectives

We estimated and compared the residual risks due to window‐period donations for pooled and apheresis platelets in Germany using a modification of a previously described statistical model. This model directly utilizes the reported interdonation intervals before a positive donation and reflects in this aspect the look‐back procedures used in haemovigilance.

Materials and Methods

Data from the German National Blood Donor Surveillance System for the years 2006–2012, including reports about donations from repeat donors with confirmed positive test results for HIV, HCV and HBV, were used to estimate the risk of undetected infectious units for both pooled and apheresis platelets.

Results

Demographics of whole‐blood and apheresis donors differed in age, gender, catchment area and interdonation interval. These differences impact on the prevalence and incidence of transfusion relevant infections and consequently the residual risk. The estimates for the residual risks for pooled and apheresis platelets were comparable. For HIV, there was no significant difference, for HCV apheresis platelets had a lower residual risk, whereas pooled platelets had a lower risk for undetected HBV infections.

Conclusion

These findings do not support calls for a shift to an apheresis platelets‐only policy in Germany.
Singularity-Based Four-Bar Linkage Mechanism for Impulsive Torque With High Energy Efficiency
Authors: Mashimo Tomoaki , Urakubo Takateru , Kanade Takeo
Published: October 2014

We propose a mechanism that exploits the singular configuration in a closed-loop four-bar linkage that can produce a high impulsive torque (a high torque for a short period in time) at the start of motion and high angular velocity during the successive motion. Such characteristics make the mechanism suitable for executing with high energy efficiency a certain class of tasks, such as lifting heavy objects. In this paper, we define the singularity-based linkage mechanism (SLM), analyze its characteristics of torque generation and energy efficiency theoretically, and then confirm them experimentally by using an SLM prototype. The performance of the SLM is compared with that of a comparable size parallelogram mechanism (PM). It is shown that the energy efficiency of the SLM comes from the fact that it achieves the high acceleration of the output link in the neighborhood of the singular configuration by providing energy with low current and high voltage to the motor; whereas the typical PM requires high current to produce the comparable impulsive torque.
Analysis and Optimization of a New Differentially Driven Cable Parallel Robot
Authors: Khakpour Hamed , Birglen Lionel , Tahan Souheil-Antoine
Published: October 2014

In this paper, a new three degrees of freedom (DOF) differentially actuated cable parallel robot is proposed. This mechanism is driven by a prismatic actuator and three cable differentials. Through this design, the idea of using differentials in the structure of a spatial cable robot is investigated. Considering their particular properties, the kinematic analysis of the robot is presented. Then, two indices are defined to evaluate the workspaces of the robot. Using these indices, the robot is subsequently optimized. Finally, the performance of the optimized differentially driven robot is compared with fully actuated mechanisms. The results show that through a proper design methodology, the robot can have a larger workspace and better performance using differentials than the fully driven cable robots using the same number of actuators.
Manufacturing Signature for Tolerance Analysis
Authors: Wilma Polini , Giovanni Moroni
Published: October 2014

Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The present work investigates the effects of considering the manufacturing signature in solving a tolerance stack-up function. A new variational model was developed that allows to deal with the form tolerance. It was used to solve a case study involving three parts with or without considering the correlation among the points of the same surface due to the manufacturing signature. A sensitivity analysis was developed by considering different values of the applied geometrical tolerances.
Servers Powered by a 10kW In-Rack Proton Exchange Membrane Fuel Cell System
Authors: Zhao Li , Brouwer Jacob , James Sean , Siegler John , Peterson Eric , Kansal Aman , Liu Jie
Published: October 2014

To improve the reliability and the energy efficiency of datacenters, as well as to reduce infrastructure costs and environmental impacts, we demonstrated and evaluated the use of a 10 kW Proton Exchange Membrane Fuel Cell (PEMFC) stack and system for powering the servers in a data center.

In this study, we designed, tested and demonstrated a PEMFC system as a Distributed Generation (DG) prime mover that has high reliability and efficiency for both steady state and dynamic operations. The 10kW PEMFC stack and system was designed to power a server rack and eliminate the power distribution system in the datacenter. The steady state electrical properties such as efficiency and polarization curves were evaluated. The ramp rate and dynamic response of the PEMFC system to server and system dynamics was also characterized and can be used to determine energy storage requirements and develop optimal control strategies to enable the dynamic load following capability.
Determination of Activation Losses in Proton Exchange Membrane Fuel Cells
Authors: Niya Seyed Mohammad Rezaei , Hoorfar Mina
Published: October 2014

Activation overpotentials, due to the reaction kinetics at the surface of the electrodes are the dominant losses in low current densities in proton exchange membrane (PEM) fuel cells. Although the Butler-Volmer equation can be employed to model the reactions at the anode and cathode, there are still ambiguities regarding the estimation and modeling of the activation losses. In this paper, the Butler-Volmer equation for both the anode and cathode is simplified. It is shown that the anode activation overpotential can be modeled using the linearized Butler-Volmer equation. The cathode activation overpotential is determined using Tafel equation. The both equations are discussed to be very accurate in the entire range of fuel cell performance. The total activation overpotential is then determined.
Development of a PEM Fuel Cell 2D-Model With Experimental Validation to Study Heterogeneities Along the Cell Surface
Authors: Robin Christophe , Gerard Mathias , Bultel Yann , Masset Franck
Published: October 2014

In this work, a PEM fuel cell 2D-model was developed to investigate the heterogeneities existing at the surface of a cell. A study on the effects of the operating conditions on the performance and durability was carried out. An experimental validation was conducted.
Operating Conditions and System Considerations for a Reversible Solid Oxide Cell System for Electrical Energy Storage
Authors: Wendel Christopher H. , Kazempoor Pejman , Braun Robert J.
Published: October 2014

Electrical energy storage (EES) is an important component of the future electric grid. Given that no other widely available technology meets all the EES requirements, reversible (or regenerative) solid oxide cells (ReSOCs) working in both fuel cell (power producing) and electrolysis (fuel producing) modes are envisioned as a technology capable of providing highly efficient and cost-effective EES. However, there are still many challenges from cell materials development to system level operation of ReSOCs that should be addressed before widespread application. One particular challenge of this novel system is establishing effective thermal management strategies to maintain the high conversion efficiency of the ReSOC. The system presented in this paper employs a thermal management strategy of promoting exothermic methanation in the ReSOC stack to offset the endothermic electrolysis reactions during charging mode (fuel producing) while also enhancing the energy density of the stored gases. Modeling and parametric analysis of an energy storage concept is performed using a thermodynamic system model coupled with a physically based ReSOC stack model. Results indicate that roundtrip efficiencies greater than 70% can be achieved at intermediate stack temperature (∼680°C) and pressure (∼20 bar). The optimal operating conditions result from a tradeoff between high stack efficiency and high parasitic balance of plant power.
Experimental Performance Evaluation of a Catalytic Flat Plate Fuel Reformer for Fuel Cell Grade Reformate
Authors: Das Susanta K. , Berry K. Joel
Published: October 2014

Compact and efficient fuel reforming system design is a major challenge because of strict requirements of efficient heat distribution on both the reforming and combustion side. As an alternative to traditional packed bed tubular reformers, catalytic flat plate fuel reformer offers better heat integration by combining the combustion reaction on one side and reforming reaction on the other side. In this study, with the help of a two-dimensional computational fluid dynamics (CFD) model, a catalytic flat plate fuel reformer is built and investigated its performance experimentally. The CFD model simulation results help to capture the effect of design parameters such as catalyst layer thickness, reaction rates, inlet temperature and velocity, and channel height. The CFD model study results also help to design and built the actual reformer in such a way that eliminate the limitations or uncertainties of heat and mass transfer coefficients. In our study, we experimentally evaluated the catalytic flat plate fuel reformer performance using natural gas. The effect of reformate gas on the current-voltage characteristics of a 5kW high temperature PEM fuel cell (HTPEMFC) stack is investigated extensively. The results shows that the overall system performance increases in terms of current-voltage characteristics of HTPEMFC while fed with reformate directly from the catalytic flat plate reformer.
Dynamic Modeling of SOFC Cogeneration Systems for Light Commercial Applications
Authors: Albrecht Kevin J. , Braun Robert J.
Published: October 2014

One potentially attractive application of solid oxide fuel cells (SOFCs) is for combined heat and power (CHP) in light commercial buildings. An SOFC-based CHP system can be employed to efficiently serve building thermal and electric loads, thereby lowering utility bills and offering many distributed generation benefits. It is often desirable to operate SOFCs in a predominately base load manner from a hardware viewpoint. However, systems in practice will experience some load dynamics during their lifetime and furthermore, optimal economic dispatch of CHP systems frequently recommends a load-following strategy. Thus, the present work is motivated by the need to understand the dynamic response capabilities of SOFC-CHP systems. Part-load performance and dynamic load-following capabilities of a 24 kW planar SOFC system for light commercial applications was investigated through computational modeling. The SOFC and balance-of-plant component models were implemented in gPROMS modeling software. The modeling strategy of each system component and associated transients are discussed. A dynamic SOFC channel-level model, which has been verified against experimental cell data, was integrated with additional balance-of-plant (BOP) component models consisting of a fuel reformer, tail gas combustor, turbomachinery, heat exchangers, and bypass valves. The performance of the system at part-load operation displays increases in electrical efficiency and decreases in CHP efficiency, as well as a more uniform PEN temperature profile. Modeling comparisons between the responses of systems consisting of either dynamic or steady-state BOP component models are reported. A fully dynamic system-level model displays anodic fuel depletion effects and waste heat recovery transients not captured by the steady-state models. The dynamics influence the ability of an SOFC system to load follow indicating when thermal and electric storage may be necessary.
Crack Propagation Resistance in Thickness Direction of Proton Exchange Membrane (PEM)
Authors: Sasaki Yusuke , Kai Yusuke , Omiya Masaki , Uchiyama Tomoaki , Kumei Hideyuki
Published: October 2014

Mechanical reliabilities of membrane electrode assemblies (MEA) in polymer electrolyte fuel cells (PEFCs) are a major concern to fuel cell vehicles. Especially, MEAs are designed to be thinner for obtaining higher generating performance and reducing cost. Proton exchange membranes (PEM) in MEA are especially important parts. When PEFCs generate power, MEAs are in high temperature and water is generated. Hygro-thermal cyclic conditions induce the mechanical stress in MEA and cracks are formed on catalyst layers. Once cracks form on catalyst layers, cracks may propagate into PEM or on the interface between the catalyst layer and PEM. The failures of PEM induce the leak of fuel gases and result in the shortage of output power. Therefore, in order to ensure the durability of thin MEAs, it is important to know the fracture resistance of PEM.

The deformation of PEM is constrained by coated catalyst layers and crack propagates into thickness direction of PEM under the constrained condition. However, there are no available data for the fracture resistance of cracks propagating into thickness direction in MEA, because of the difficulty of measurements. Therefore, in this paper, we try to measure the fracture resistance of cracks propagating into thickness direction in PEM under several environmental conditions. Elastic-plastic fracture toughness tests for PEM were carried out in temperature and humidity controlled chamber. The results showed that the fracture resistances of crack propagation into thickness direction of PEM were strongly affected by temperature and humidity conditions.
Developments of Thin-Film Temperature and Humidity Sensors for PEMFC In-Situ Measurements
Authors: Sugimoto Toshiki , Horiuchi Yuhei , Araki Takuto
Published: October 2014

Proton exchange membrane fuel cells (PEMFCs) are useful systems because they operate at lower temperatures than other types of fuel cells. This characteristic causes water management issues. To elucidate effects of water on PEMFC performance, we developed a temperature sensor using micro-electro-mechanical systems (MEMS) techniques. This sensor was placed between the catalyst layer (CL) and the microporous layer (MPL) at the cathode. Slight effects on total cell performance were observed with the insertion of the sensor. This sensor can be applicable to typical PEMFCs without any special equipment such as a transparent separator. In-situ measurement with a temperature sensor showed that the maximum temperature rise at the cathode CL (CCL) was about 9 °C at 1.1 A/cm2. The temperature sensor also showed temperature gradients between the ribs and channels. In addition, we developed a capacitance-type humidity sensor and inserted it in the channel. In-situ measurement with a humidity sensor showed a relative humidity (RH) change in the channel. This sensor can detect not only RH but also accumulated water in the channel. Liquid water appeared in the channel at 0.7 A/cm2.
Electrochemical- and Thermal-Performance Model of a High-Temperature SOFC System for Geothermic Fuel Cell Application
Authors: Anyenya Gladys A. , Sullivan Neal P. , Braun Robert J. , Haun Buddy , Daubenspeck Mark
Published: October 2014

A one-dimensional model of a high-temperature solid-oxide fuel cell (SOFC) stack contained in a geothermic fuel cell (GFC) assembly is presented. The GFC concept, developed by IEP Technology Inc., involves the harnessing of heat generated during SOFC stack operation for the liberation of oil and gas from oil shale. The first GFC prototype, designed and built by Delphi Automotive, LLC., is comprised of three 1.5-kW SOFC stacks housed in a stainless-steel casing. Hot exhaust gases exiting the stacks are directed out of the stack-containment vessel, rejecting heat to the surroundings before being exhausted above ground. The primary aims of this work are to develop modeling tools to (1) predict the stack electrochemical performance and (2) elucidate the thermal characteristics of the stack assembly during operation through modeling and simulation. Aspen Plus process-simulation software and an embedded electrochemical model are utilized to predict the temperature dynamics and the electrical output of the GFC stack. The stack performance is decomposed with a temperature-dependent Area Specific Resistance (ASR) obtained from analysis of experimental data from a single stack that was operated over a wide temperature range. Independent full-scale stack testing has enabled performance validation of the electrochemical model. Experimental data from the three-stack GFC assembly has been used to calibrate the thermal-modeling approaches and the external heat-rejection predictions. Simulation results for steady-state conditions under hydrogen fuel are presented and compared to experimental data from thermocouples on the GFC prototype. The model will be used to explore the interaction of the geothermic fuel cell with the oil-shale formation in which it is installed.
Control Impacts of Cold-Air Bypass on Pressurized Fuel Cell Turbine Hybrids
Authors: Pezzini Paolo , Celestin Sue , Tucker David
Published: October 2014

A pressure drop analysis for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide means of evaluating risk mitigation strategies.

The cold air bypass in the Hyper facility directs compressor discharge flow to the turbine inlet duct, bypassing the fuel cell and exhaust gas recuperators in the system. This valve reduces turbine inlet temperature while reducing cathode airflow, but significantly improves compressor surge margin. Regardless of the reduced turbine inlet temperature as the valve opens, a peak in turbine efficiency is observed during characterization of the valve at the middle of the operating range. A detailed experimental analysis shows the unusual behavior during steady state and transient operation, which is considered a key point for future control strategies in terms of turbine efficiency optimization and cathode airflow control.
Mechanical Damage Propagation in Polymer Electrolyte Membrane Fuel Cells due to Hygrothermal Fatigue
Authors: Banan Roshanak , Bazylak Aimy , Zu Jean W.
Published: October 2014

Temperature and relative humidity cycles play an important role in the initiation and propagation of mechanical damage in the PEM fuel cell membrane electrode assembly (MEA). However, there have been few studies on the mechanical damage evolution in PEM fuel cells due to humidity and temperature variations. In this study, we investigate the damage propagation in the MEA, with a special focus on the membrane/CL interface. A finite element model based on cohesive zone theory is developed to describe the effect of relative humidity (RH) amplitude on mechanical damage propagation in the MEA. Results showed that having larger RH variation in the applied cycles can result in up to 3.4 times higher fatigue stresses at the interface, and hence a considerably faster rate for delamination propagation.
Hydrogen Production of a Heavy Hydrocarbon Fuel Autothermal Reformer on NiO-Rh Based Monolithic Catalysts
Authors: Xu Xinhai , Zhang Shuyang , Li Peiwen
Published: October 2014

Catalytic autothermal reforming (ATR) is one promising technology to effectively produce hydrogen and syngas from heavy hydrocarbon fuels for fuel cell applications. The present study describes the development of a cylindrical 1.5 kWe scale autothermal reformer for on-board SOFCs. NiO-Rh bimetallic catalysts supported on 400 cpsi cordierite monoliths were experimentally examined in the reformer. Promoters including cerium, potassium and lanthanum were introduced in the catalysts preparation to improve their performance. Dodecane (C12H26) was used as a surrogate for desulfurized commercial Jet-A fuel (C11.6H22.3) to study the hydrogen selectivity and efficiency of ATR reactions with different catalysts. Gas chromatography (GC) equipped with TCD detector was used to monitor the concentration of H2, CO, CO2 and N2 in the reformate. The catalysts screening tests were performed at the same operation conditions including inlet temperatures, reactor temperature, steam to carbon ratio and oxygen to carbon ratio. The best catalyst was reported to have efficiency about 85 percent. The optimized reactor operation temperature was reported as 700 °C.
Improved Passive Water Management Design for Use in Unitized Regenerative Fuel Cells
Authors: Lele Sandeep S. , Sizemore Michael A. , Fabris Drazen
Published: October 2014

Proton Exchange Membrane (PEM) fuel cells require effective water transport away from the cathode to ensure stable operation. Many existing water management strategies involve active methods, reducing system efficiency by introducing parasitic losses. In the present work, we report on the improved design and fabrication of a passive water management scheme involving UV-catalyzed porous polymer wicks. The design features two connected porous domains consisting of a methacrylate-based transport layer and polyvinyl alcohol storage layer.

In our previous prototype, large water transport lengths (∼12 mm) prevented adequate removal of generated water. The capillary pressure drop across the two porous domains was insufficient to drive a flow rate matched to the rate of generation. Thus, the current design produces a shorter transport distance (∼3 mm) by developing a new vertical design. An independently produced SU-8 photolithographic mold is incorporated to improve the fabrication process.
Definition and Cost Evaluation of Fuel Cell Bus and Passenger Vehicle Power Plants
Authors: James Brian D. , Moton Jennie M. , Colella Whitney G.
Published: October 2014

A design for manufacture and assembly (DFMA™) analysis is applied to future bus and automotive fuel cell vehicle (FCV) system designs. This DFMA™ analysis is used to identify (1) optimal fuel cell system (FCS) operating parameters for system cost minimization, (2) FCV designs appropriate for volume manufacture, (3) FCV manufacturing supply chain designs, (4) projected future capital costs of FCVs at varying manufacturing rates, and (5) primary cost drivers. This DFMA™ analysis focuses on the FCS drive train. It excludes fuel storage, the electric drive drain, and all other parts of the vehicle (chassis, exterior, etc.). These FCSs are envisioned to use low temperature proton exchange membrane (LT PEM) stacks to convert hydrogen fuel into electric power. Models are developed to minimize LT PEM fuel cell system costs by finding the cost optimal combination of (1) stack operating pressure, (2) cell voltage, (3) platinum (Pt) catalyst loading, (4) stoichiometric ratio of oxygen, and (5) coolant stack exit temperature. A multi-variable Monte Carlo sensitivity analysis indicates, with 90% confidence, that a FCS producing peak net 160 kilowatt-electric (kWe) for a bus application and produced at a rate of 1,000 FCS/year (yr) is expected to cost between $251/kWe and $334/kWe. Similarly, a peak net 80 kWe automotive FCS manufactured at a rate of 500,000 FCSs/year is estimated to cost between $51/kWe and $65/kWe, with 90% confidence. Total FCS costs are the sum of PEM stack and balance of plant (BOP) costs. The BOP components represent 32% of the bus FCS costs and 48% of the automotive system cost.
Solid Oxide Fuel Cell Degradation, Recovery and Control via the Electrical Terminals
Authors: Lindahl Peter A. , Hu Xuelei , Wold Joshua , Cornachione Matthew , Shaw Steven R.
Published: October 2014

This paper presents results from an investigation concerning load-induced degradation, recovery, and control of solid oxide fuel cells (SOFCs). In this study, commercially available SOFCs were subject to extended over-current conditions, followed by periods of open-circuit operation. During times of current loading, degradation was observed in the cells’ electrical performance through polarization and electrochemical impedance spectroscopy (EIS) measurements. These measurements showed an increase in the polarization curve’s ohmic region slope, i.e. large-signal resistance, as well as an increase in the cell’s small-signal low-frequency impedance. The degradation was temporary however, as the electrical performance recovered during times of open-circuit operation. These results, attributed to electrochemically-induced oxidation and reduction of nickel in the anode, suggest the degradation phenomenon is controllable via the electrical terminals. As such, an additional test was performed on an SOFC powering a pulse-width modulated load, with the load’s duty-cycle negatively proportional to the cell’s large-signal resistance. Polarization and EIS measurements taken during this test showed that despite the controlled load, degradation occurred throughout the test. However, post-test scanning electron microscope images revealed cracks in the cell’s cathode along the boundary between the active and bulk layers. This type of cracking was not observed in the original degradation and recovery tests, suggesting that the degradation observed in the controlled load test was irreversible and caused by a separate phenomenon.
Exergy Analysis of Combined Cycle of SOFC-Gas Turbine Using Coal-Base Syngas at Different Mixture Compositions
Authors: Zouhri Khalid
Published: October 2014

Detailed analysis of exergy on the integrated gasification combined cycle (IGCC) incorporated with a solid oxide fuel cell (SOFC) was conducted to explore the performance characteristics of the system. The exergy destruction and exergy efficiency were analyzed at different syngas mixture compositions by varying the compressor pressure ratio. SOFC-gas turbine system included gasifier, gas cooler, SOFC, compressor and gas turbine, combustion chamber and heat recovery system generator. Results showed that using hydrogen-enriched syngas mixture increased the net power and the exergy efficiency. The highest exergy destruction occurred at the gasifier, and combustion chamber.
Graphene as Cathode Material in Molten Carbon Fuel Cells
Authors: Zouhri Khalid , Yassar Reza S.
Published: October 2014

The molten carbonate fuel cell (MCFC) is considered one of the best technologies for stationary power. This is due to its high efficiency, medium–high operating temperature, and low emissions. The MCFC operates at a temperature range from 600oC to 700oC and normally is combined with the gas turbine (GT) as a topping cycle. This work investigates the impact of Platinum/Graphene (Pt/G) on a combined cycle of MCFC-GT by applying the first and second laws of thermodynamics. The maximum work output of the hybrid cycle is ultimately calculated to be 1350 kW. The overall exergy efficiency achieved is 59.82%. Our findings reveal that there is an average 23% gain in the maximum work output, energy and exergy efficiencies when Pt/G is used as the cathode material compared to other materials such as Platinum/Carbon (Pt/C) and Platinum/Carbon cloth (Pt/CC).
Adaptive Control of a Nonlinear Fuel Cell-Gas Turbine Balance of Plant Simulation Facility
Authors: Tsai Alex , Tucker David , Emami Tooran
Published: October 2014

A 300kW Solid Oxide Fuel Cell Gas Turbine (SOFC-GT) power plant simulator is evaluated with the use of a Model Reference Adaptive Control scheme, implemented for a set of nonlinear empirical Transfer Functions. The SOFC-GT simulator allows testing of various fuel cell models under a Hardware-in-the-Loop configuration that incorporates a 120kW Auxiliary Power Unit, and Balance-of-Plant components in hardware, and a fuel cell model in software. The adaptation technique is beneficial to plants having a wide range of operation, and strong coupling interaction. The practical implementation of the adaptive methodology is presented through simulation in the MATLAB/SIMULINK environment.
SOFC Lifetime Assessment in Gas Turbine Hybrid Power Systems
Authors: Tucker David , Harun Nor Farida , Abreu-Sepulveda Maria
Published: October 2014

The adoption of solid oxide fuel cell (SOFC) technology in power generation has been limited, in no small part, by material degradation issues affecting the stack lifetime, and hence, the economic viability. A numeric study was conducted to determine if the life of an SOFC could be extended when integrated with a recuperated gas turbine system. Dynamic modeling tools developed at the National Energy Technology Laboratory (NETL) for real-time applications were applied to evaluate life to failure for both a standalone SOFC and a hybrid SOFC gas turbine. These models were modified using empirical relations to experimental degradation data to incorporate degradation as a function of current density and fuel utilization. For the control strategy of shifting power to the turbine as fuel cell voltage degrades, the SOFC life could be extended dramatically, significantly impacting the economic potential of the technology.
The Economic Performance of an Integrated Biogas Plant and Proton Exchange Membrane Fuel Cell Combined Heat and Power System (PEMFC-CHP) in Sweden
Authors: Guan Tingting , Alvfors Per
Published: October 2014

A Proton Exchange Membrane Fuel Cell Combined Heat and Power system (PEMFC-CHP) fuelled by the hydrogen-rich gas reformed from biogas may be seen as an efficient and sustainable technology. This system can provide electrical and thermal energy dynamically to residential applications. In this study, an assessment of the economic performance of an integrated biogas plant and PEMFC-CHP for Swedish electricity and heat prices is presented. The economic factors considered are the capital and operation & maintenance (O&M) costs of the biogas plant and the PEMFC-CHP, the price of heat and electricity, and the value of the digestate as fertilizer. The analysis includes two cases: 1) both biogas plant and PEMFC-CHP are located on the farm. The farm sells the electricity and heat to the power grid and district heating system, respectively; 2) the PEMFC-CHP is located in a centralized-biogas plant, not on the farm. The manure is transported from farms to the plant. The plant also sells the electricity and heat to the power grid and district heating system. The results show that the farm-based and the centralized biogas plant have almost the same biogas production cost. The electricity cost of today, expected for 2020, and for the break-even of this integrated system are 530, 305 and 197 €/MWh, respectively. With the current trend of the fuel cell industry development, this break-even price may be reached in the near future.
Trends in Physical Activity and Sedentary Behaviors of United States Youth
Authors: Bassett David R. , John Dinesh , Conger Scott A. , Fitzhugh Eugene C. , Coe Dawn P.
Published: October 2014

Background:

Increases in childhood and adolescent obesity are a growing concern in the United States (U.S.), and in most countries throughout the world. Declines in physical activity are often postulated to have contributed to the rise in obesity rates during the past 40 years.

Methods:

We searched for studies of trends in physical activity and sedentary behaviors of U.S. youth, using nontraditional data sources. Literature searches were conducted for active commuting, physical education, high-school sports, and outdoor play. In addition, trends in sedentary behaviors were examined.

Results:

Data from the Youth Risk Behavior Surveillance System (YRBSS) and other national surveys, as well as longitudinal studies in the transportation, education, electronic media, and recreation sectors showed evidence of changes in several indicators. Active commuting, high school physical education, and outdoor play (in 3- to 12-year-olds) declined over time, while sports participation in high school girls increased from 1971 to 2012. In addition, electronic entertainment and computer use increased during the first decade of the 21st century.

Conclusions:

Technological and societal changes have impacted the types of physical activities performed by U.S. youth. These data are helpful in understanding the factors associated with the rise in obesity, and in proposing potential solutions.
Walk, Bicycle, and Transit Trips of Transit-Dependent and Choice Riders in the 2009 United States National Household Travel Survey
Authors: Lachapelle Ugo
Published: October 2014

Background:

Previous research has shown that public transit use may be associated with active transportation. Access to a car may influence active transportation of transit riders.

Methods:

Using the 2009 United States National Household Travel Survey (NHTS), transit users ≥ 16 years old (n = 25,550) were categorized according to driver status and number of cars and drivers in the household. This typology ranged from choice transit riders (ie, “fully motorized drivers”) to transit-dependent riders (ie, “unmotorized nondriver”). Transit trips, walking trips, and bicycling trips of transit users are estimated in negative binomial models against the car availability typology.

Results:

Sixteen percent of participants took transit in the past month; most (86%) lived in car-owning households. As income increased, car availability also increased. Transit user groups with lower car availability were generally more likely than fully motorized drivers to take more public transit, walking, and bicycle trips. Transit riders have varying levels of vehicle access; their use of combinations of alternative modes of transportation fluctuates accordingly. Transit-dependent individuals without cars or sharing cars used active transportation more frequently than car owners.

Conclusion:

Policies to reduce vehicle ownership in households may enable increases in the use of alternative modes of transportation for transit users, even when cars are still owned.
Imaging Enterobacteriaceae infection in vivo with
18
F-fluorodeoxysorbitol positron emission tomography
Authors: Weinstein Edward A. , Ordonez Alvaro A. , DeMarco Vincent P. , Murawski Allison M. , Pokkali Supriya , MacDonald Elizabeth M. , Klunk Mariah , Mease Ronnie C. , Pomper Martin G. , Jain Sanjay K.
Published: October 2014

2-[
18
F]-Fluorodeoxysorbitol, a synthetic PET probe, can be used to rapidly, sensitively, and specifically image Gram-negative bacterial infections in animals.
TOPK inhibitor induces complete tumor regression in xenograft models of human cancer through inhibition of cytokinesis
Authors: Matsuo Yo , Park Jae-Hyun , Miyamoto Takashi , Yamamoto Shinji , Hisada Shoji , Alachkar Houda , Nakamura Yusuke
Published: October 2014

TOPK inhibitor kills cancer cells by causing a cytokinesis defect and promotes tumor regression in mouse models.
Elbow Grease
Authors: Spiller Kara L.
Published: October 2014

A biomimetic strategy to bind hyaluronic acid to joint and eye surfaces effectively increases lubrication.
DNA Methylation
Authors: Marinus M. G. , Løbner-Olesen A.
Published: October 2014

The DNA of
Escherichia coli
contains 19,120 6-methyladenines and 12,045 5-methylcytosines in addition to the four regular bases, and these are formed by the postreplicative action of three DNA methyltransferases. The majority of the methylated bases are formed by the Dam and Dcm methyltransferases encoded by the

dam

(DNA adenine methyltransferase) and

dcm

(DNA cytosine methyltransferase) genes. Although not essential, Dam methylation is important for strand discrimination during the repair of replication errors, controlling the frequency of initiation of chromosome replication at
oriC
, and the regulation of transcription initiation at promoters containing GATC sequences. In contrast, there is no known function for Dcm methylation, although Dcm recognition sites constitute sequence motifs for Very Short Patch repair of T/G base mismatches. In certain bacteria (e.g.,
Vibrio cholerae
,
Caulobacter crescentus
) adenine methylation is essential, and, in
C. crescentus
, it is important for temporal gene expression, which, in turn, is required for coordinating chromosome initiation, replication, and division. In practical terms, Dam and Dcm methylation can inhibit restriction enzyme cleavage, decrease transformation frequency in certain bacteria, and decrease the stability of short direct repeats and are necessary for site-directed mutagenesis and to probe eukaryotic structure and function.
Amiodarone-induced thyrotoxicosis: type 1 or type 2?
Authors: Khan Ahsan , Puttanna Amar , Raskauskiene Diana
Published: October 2014

A 69-year-old man presented with a 6-week history of shortness of breath on exertion, unintentional weight loss, altered bowel habits and lethargy. He was diagnosed with atrial fibrillation 2 years previously and started on amiodarone and warfarin. He subsequently reverted to sinus rhythm and his medication was stopped 1 year prior to presentation. He denied history of thyroid dysfunction. On examination, he had a small firm goitre of grade I. His skin was warm and sweaty. Thyroid function tests showed him to be thyrotoxic. He was started on carbimazole 20 mg; however, he further became significantly thyrotoxic. Given the severity of his presentation and lack of any clinical or biochemical improvement, oral prednisolone 30 mg once daily was coadministered. His symptoms subsequently resolved and he became euthyroid. The prednisolone was tapered down and stopped while the carbimazole was incrementally reduced to 10 mg daily.
An ocular motility conundrum
Authors: McElnea Elizabeth Margaret , Stephenson Kirk , Lanigan Bernie , Flitcroft Ian
Published: October 2014

Two siblings, an 11-year-old boy and a 7-year-old girl presented with bilateral symmetrical ptosis and limited eye movements. Having already been reviewed on a number of occasions by a variety of specialists in multiple hospital settings a diagnosis of their ocular motility disorder had remained elusive. We describe their cases, outline the differential diagnosis and review the investigations performed which were influential in finally making a diagnosis.