bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a Triple Effect Absorption Air Conditioning System Integrated With PEM Fuel Cell
Authors: Gadalla Mohamed , Ratlamwala Tahir Abdul Hussain , Dincer Ibrahim
Published: December 2010

In this paper, a parametric study of the TEARS integrated with PEM fuel cell is conducted in order to investigate the effect of different operating parameters on the COPs and utilization factor of the integrated system. It is found that when the inlet temperature of the HTG is increased, the energetic and exergetic COPs vary in an exponential form from 0.56 to1.86, and 0.28 to 0.964, respectively, and the heat input decreases from 34.4 kW to 9.802 kW. When the high pressure of the TEARS system is increased, both the COPs decrease, ranging from 4.4% to 9.9%, while the heat input increases by 6%. Also, an increase in the cooling load of the TEARS for different heat input results in the variation of the COPs from 0.17 to 3.4. Moreover, a parametric study for PEM fuel cell is carried out at an optimum practical operating condition of cooling load of 20 kW and heat input of 9.802 kW for TEARS, which results in the energetic and exergetic COPs of 1.86, and 0.964, respectively. The optimum area of the cell is found to be varying from 0.436 to 54.5 m2 for different current densities pressures and temperatures. However, increase in the area of the cell resulted in the higher efficiency of the cell, ranging from 27.5% to 42%. Moreover, when the molar flow rate is increased, the utilization factor of the system is found to be decreasing exponentially ranging from 77% to 35%. This study reveals that an integrated air conditioning system with fuel cell is an attractive economical and environmental solution when compared with conventional systems of high electricity and natural gas prices.
Metal-Supported SOFC on Compressed Ni-Al Foam Substrates
Authors: Smirnova Alevtina , Sadykov Vladislav , Mezentseva Natalia , Usoltsev Vladimir , Smorygo Oleg , Bobrenok Oleg , Uvarov Nikolai
Published: December 2010

This work presents results of design and characterization of metal-supported SOFC using a new type of metallic substrate made of foam Ni-Al alloy compatible with other cell components. Anode nanocomposites NiO/YSZ with graded grain size and porosity were supported via slip casting. A thin (∼ 10 μm) layer of YSZ was supported by MOCVD. Functionally graded layered cathode LSM/LSM+ScCeSZ was supported by electrostatic spray deposition. For button-size cells a power density up to 500 mW/cm2 at 700 °C was obtained using wet H2-air feeds. Cell performance was stable without degradation at short–term tests (∼100h) at 600–800 °C.
A Self-Supported 40W Direct Methanol Fuel Cell (DMFC) System
Authors: Ayyappan Manokaran , Rajavel Vijayakumar , Nellimoottil Thomman Thomas , Parthasarathi Sridhar , Sethuraman Pitchumani , Shukla Ashok K.
Published: December 2010

A self-supported 40W Direct Methanol Fuel Cell (DMFC) system has been developed and benchmarked for its performance. The system consists of a DMFC stack comprising 15-cells with an electrode area of 45cm2, and auxiliaries comprising a methanol sensor, a liquid-level indicator, fuel and air pumps that consume a total power of about 5W. The self-supported system addresses issues (a) related to water recovery from the cathode exhaust, (b) maintaining a constant methanol-feed-concentration, and (c) the thermal management in the system. Methanol and water are pumped to the methanol-mixing tank where the liquid level is monitored and controlled with the help of a liquid-level indicator. During the operation, concentration of methanol in the solution at the outlet of the stack is monitored, and required amount of methanol is added in the feed tank to restore the initial concentration employing a methanol-loop system connected to a methanol sensor that helps monitoring and controlling the system output at a steady value; product water from cathode is recovered and re-circulated for diluting the methanol feed as desired. The feed-rate requirements of methanol fuel and oxidant air are optimized for the stack capacity of 40W. The salient features of the system are: (i) flexible and modular construction, (ii) controlled-output power and (ii) easy start-up and stop. The self-supported DMFC system is ideally suited for military and aerospace applications.
Computational Characterization of Mechanical Behavior of Polymer Electrolyte Membrane Based on Nonaffine Molecular Chain Model
Authors: Riku Isamu , Morizane Kyosuke , Mimura Koji
Published: December 2010

In this paper, a computational model is constituted based on the microstructural features of polymer electrolyte membrane (PEM). Assuming that the interaction between the water molecular and PEM molecular is quite weak, the cluster inside PEM is considered as void and the homogenization method is applied to constitute a unit cell model in which several voids are contained to represent the periodic microstructure of PEM. On the other hand, to account for the nonaffine movement of the molecular chains of PEM, the number of segment in a single chain is proposed as a function of the local stretch of the molecular chain and the constitutive equation of the matrix of PEM is constituted based on the nonaffine molecular chain model. It is found that this proposed model can reproduce the strain softening deformation behavior of PEM very well. Furthermore, a series simulations based on this proposed model are performed to discuss the effect of the water content and that of the triaxiality of macroscopic loading condition on the mechanical behavior of PEM. The results show that a relative quick development of the number of segments in a single chain is observed in the case of high water content and high triaxiality loading condition.
Design and Analysis of a Direct Borohydride Fuel Cell DC-DC Converter for Portable Applications
Authors: Zhou Xiao , Park Sung-Yeul
Published: December 2010

Due to high power density and reactivity compared with the use of gaseous hydrogen as the fuel, direct borohydride fuel cell (DBFC) is becoming an emerging renewable energy source. In this paper, DBFC characteristic is analyzed based on the frequency response measurement and test with different load conditions. The equivalent circuit of DBFC is obtained from the DBFC characteristic. A dc-dc converter is designed from the frequency domain and verified its performance at time domain with transient load test. Based on the combined model analysis of DBFC and the dc-dc converter, transient response of the model is discussed. In addition, load transient response tests with power supply and DBFC have been compared. A prototype of dc-dc boost converter for 5-cell DBFC has been built and tested.
A Parametric Study on the Planar SOFC Performance Using the Three-Dimensional Transport Equations With Electrochemical Reaction
Authors: Choi Bong Hwan , Choi Do Hyung , Park Hun Kwan
Published: December 2010

A three-dimensional heat/fluid flow analysis procedure to predict the planar SOFC performance has been developed. The continuity, Navier-Stokes, energy and species equations, coupled with the electro-chemical relation models, are solved for the single periodic module of a unit cell which is composed of the anode/cathode channels, the porous electrodes, the electrolyte, and the interconnect. Using the FVM method of SIMPLE type, the local current density, which is proportional to the rate of chemical reaction, is determined iteratively by forcing the local current density and the mass-transfer rate at the reacting surface match. The Butler-Volmer equation is used to estimate the activation overpotential while the diffusion in the porous electrodes is simulated to accurately predict the concentration overpotential. Upon validation of the procedure, the average current density and voltage relation has been successfully obtained for the given structure. The cell characteristics, which include the local current density, temperature, and concentration distributions, are presented and discussed. The effects of various parameters, namely, the inlet temperature, the electrode thickness, and the channel/rib width, on the cell performance are carefully examined for different electric loads.
Transient Performance of Integrated SOFC System Including Spatial Temperature Control
Authors: Mueller Fabian , Fardadi Mahshid , Shaffer Brendan , Brouwer Jacob , Jabbari Faryar
Published: December 2010

Spatial temperature feedback control has been developed for a simulated integrated non-pressurized simple cycle solid oxide fuel cell (SOFC) system. The fuel cell spatial temperature feedback controller is based on (1) feed-forward set-points that minimize temperature variation in the fuel cell electrode-electrolyte solid temperature profile for the system operating power range, and (2) decentralized proportional-integral based feedback to maintain the fuel cell spatial temperature profile during transients and disturbances. Simulation results indicate the fuel cell spatial temperature variation can be maintained within 15 degrees of nominal to significant load perturbations. Temperature gradients through the fuel cell are needed to remove the heat generated within the cell and cannot be avoided. The goal of the developed spatial temperature control is to minimize temperature variations from a nominal temperature profile in time. Minimal temperature variations in the SOFC electrode-electrolyte solid assembly will result in decreased thermal stresses and thereby decreased degradation and probability-of-failure. Simulation results demonstrating the ability to maintain the SOFC spatial temperature during large load perturbations indicates SOFC could be designed and controlled for rapid load following capability. Such performance can greatly improve SOFC system operating flexibility and thereby open new markets for SOFC systems including load following or spinning reserve services for the utility grid.
Washcoating Copper Catalyst With Various Metal Oxides Sol Onto Microchannel Reactor for Steam Reforming of Methanol
Authors: Wang Jung-Hui , Yeh Chuin-Tih
Published: December 2010

Washcoating copper catalyst in the micro-channel reactor for steam reforming of methanol (SRM) is advantageous to get high ratio of surface area to volume. Catalyst was coated using brushing method by making slurry with different metal oxides sol as binder (ceria, zirconia and yttria). In the preparation of catalyst slurry, the solid content, ratio of catalyst to binder, pH value and solvent were investigated. The adhesion of catalyst can be compared by estimating the weight loses of washcoating layer after 130W sonication for 30 min. The crystallite, morphology, reduction temperature and chemical environment of catalysts can be characterized by XRD, SEM, TPR and OTPR. The catalyst coated with various metal oxides sol mixing water/ethanol solvent with a specific solid content and catalyst/binder ratio in the neutral solution exhibits a good adherence with the substrate. The performance of fabricated micro-reformer is investigated in the temperature range 150–300 °C. In GHSV = 60,000 h−1, the conversion reaches 80% at 210 °C, and it corresponded to the generating of hydrogen for power output of 2 W assuming a 50% fuel cell operating efficiency. Furthermore, the fabrication of microchannels reactor connecting high temperature PEMFC is investigated.
Effects of Gas Flow Rate and Catalyst Loading on Polymer Electrolyte Membrane (PEM) Fuel Cell Performance and Degradation
Authors: Okafor A. Chukwujekwu , Mogbo Hector-Martins
Published: December 2010

In this paper, the effects of gas flow rates, and catalyst loading on polymer electrolyte membrane fuel cell (PEMFC) performance was investigated using a 50cm2 active area fuel cell fixture with serpentine flow field channels machined into poco graphite blocks. Membrane Electrode Assemblies (MEAs) with catalyst and gas flow rates at two levels each (0.5mg/cm2, 1mg/cm2; 0.3L/min, 0.5L/min respectively) were tested at 60°C without humidification. The cell performance was analyzed by taking AC Impedance, TAFEL plot, open circuit voltage, and area specific resistance measurements. It was observed that MEAs with lower gas flow rate had lesser cell resistance compared to MEAs with a higher gas flow rate. TAFEL plot shows the highest exchange current density value of −2.05 mAcm2 for MEA with 0.5mg/cm2 catalyst loading operated at reactant gas flow rate of 0.3L/min signifying it had the least activation loss and fastest reaction rate. Open circuit voltage curve shows a higher output voltage and lesser voltage decay rate for MEAs tested at higher gas flow rates.
Modeling and Control of a Hybrid Fuel Delivery System Based on a Two-Phase Anodic Model of a PEM Fuel Cell
Authors: He Jinglin , Choe Song-Yul
Published: December 2010

A polymer electrolyte membrane fuel cell (PEM FC) system for automotive applications should meet the rapid variable power demand by consuming the fuel, hydrogen. The fuel delivery system is designed to supply the hydrogen from tank to fuel cell system, and sometime re-circulate exhausted hydrogen to increase the fuel efficiency and maintain the humidity at the anode side for proper water management. The pressure in anode flow channel should track the pressure in cathode flow channel to prevent high pressure difference damage on the thin layers in cells with stable stiochiometric ratio of hydrogen. In this paper, we analyze a hybrid fuel delivery system that consists of two supply and two recirculation lines including a control valve, low pressure regulator, an ejector, and a blower. A quasi-1D two-phase transient fuel cell model is incorporated into the fuel delivery system for the design of controllers. A state feed-back controller were implemented and optimized, which is integrated with the fuel delivery and fuel cell system and be simulated to evaluate its tracking and rejection performance.
Modeling a Two-Phase Control-Oriented Transient Model of a Single PEM Fuel Cell
Authors: He Jinglin , Choe Song-Yul
Published: December 2010

This paper proposed a 1D non-isothermal control-oriented transient model of PEM fuel cell unit considering the two-phase water dynamics in gas flow channel, gas diffusion layer, catalyst layer and membrane. It is known that the accumulated liquid water in the gas flow channels can block the transport path in the gas diffusion layer for the reactant gases and degrade the performance of the fuel cell, while the proper water amount in the gas flow channels and other layers can help to maintain high proton conductivity in the membrane. The I-V curve and the change of gas concentrations, liquid water amount and temperature at specific operating conditions are obtained by sweeping the current of fuel cell. The voltage, gas concentration, temperature and water dynamic changes are investigated by applying the step change of the load current. The fuel cell performance affected by temperature and water dynamics is studied by the analysis of the simulation result.
Transient Water Transport in Nafion Membranes Under Activity Gradients
Authors: Romero T. , Me´rida W.
Published: December 2010

Transient water transport experiments on Nafion of different thicknesses were carried out in the temperature range of 30 to 70 °C. These experiments report on water transport measurements under activity gradients in the time domain for liquid and vapour equilibrated Nafion membranes. Using a permeability test rig with a gated valve, the water crossover was measured as a function of time. The typical response is shown as a time dependent flux, and it shows the dynamic transport from an initially dry condition up to the final steady state. Contrarily to previous reports from dynamic water transport measurements, where the activity gradient across the membrane is absent; in this work, the membrane was subjected to an activity gradient acting as the driving force to transport water from an environment with higher water activity to an environment with lower water activity through the membrane’s structure. Measurements explored temperature and membrane thickness variation effect on the transient response. Results showed dependency on temperature and a slower water transport rate across the vapour-membrane interface than for the liquid-membrane interface. These measurements showed the transport dependency on water content at the beginning of the experiment when the membrane was in a close-to-dry condition suggesting a transport phenomenon transition due to a reached critical water content value. The new protocol for transient measurements proposed here will allow the characterization of water transport dependency on membrane water content with a more rational representation of the membrane-environment interface.
GDC-Y2O3 Oxide Based Two Phase Nanocomposite Electrolytes
Authors: Raza Rizwan , Abbas Ghazanfar , Zhu Bin
Published: December 2010

An oxide based two phase nanocomposite electrolyte (Ce0.9Gd0.1O2) was synthesized by a co-precipitation method and coated with Yttrium oxide (Y2O3). The nanocomposite electrolyte showed the significant performance of power density 750mW/cm2 and higher conductivities at relatively low temperature 550°C. Ionic conductivities were measured with electrochemical impedance spectroscopy (EIS) and DC (4 probe method). The structural and morphological properties of the prepared electrolyte were investigated by means of High Resolution Scanning Electron Microscopy (HRSEM). The thermal stability was determined with Differential Scanning Calorimetry (DSC). The particle size was calculated with Scherrer formula and compare with SEM results, 15–20 nm is in a good agreement with the SEM and X-ray diffraction (XRD) results. The purpose of the study to introduce the functional nanocomposite materials, for advanced fuel cell technology (NANOCOFC) to meet the challenges of solid oxide fuel cell (SOFC).
Least-Squares Parameter Estimation for Catalyst Layer Agglomerate Models
Authors: Dobson Peter , Secanell Marc
Published: December 2010

A framework is presented to estimate the micro-structural parameters of cathode fuel cell electrodes by means of a nonlinear least-squares method. This work represents the first attempt in the literature to characterize the structure of the catalyst layer by numerical parameter estimation using a two-dimensional membrane electrode assembly model with an ionomer-filled agglomerate catalyst layer approximation. The framework is developed by coupling a two-dimensional model to an optimization based least-squares algorithm in DAKOTA. The algorithm, NL2SOL, minimizes the sum-of-squares of the residuals for any number of data points and parameters. Employing the proposed methodology allows for accurate characterization of the electrode structure and quantification the quality of the curve fit. Extension of this methodology allows for parameter estimation as novel materials are incorporated into fuel cell construction. Results indicate that curves can be fit using micro-structural and electrochemical parameters consistent with values published in the literature. However, the quality of the fit deteriorates for large data sets over the entire range of operating conditions.
Development of Electrode Structure for High Performance Fuel Cell Using CAE
Authors: Tomiyasu Joji , Harada Takashi , Fujiuchi Makoto , Inamuro Takaji , Hyodo Shiaki , Munekata Toshihisa
Published: December 2010

Cold starting performance and high temperature operation are current issues in the development of high performance polymer electrolyte fuel cell (PEFC) electrodes. Although excess water must be removed to improve these aspects of electrode performance, it is also important to adopt a structure that prevents the electrodes from drying up. In the face of this conflicting relationship, it is therefore difficult to design an electrode structure with the required properties. For this reason, using technology jointly developed with Kyoto University and Toyota R&D Labs., Inc., the relationship between structural factors and performance was identified by applying a two-phase flow simulation to the complex microstructure of the gas diffusion layer (GDL) to optimize the electrode structure. As a result, an electrode structure was designed that improves high temperature operation while maintaining cold starting performance. The simulation results were then validated by experiments.
In-Situ Observation of the Water Distribution in Porous Layers of PEMFCs by Soft X-Ray Radiography
Authors: Sasabe Takashi , Tsushima Shohji , Hirai Shuichiro
Published: December 2010

To observe the liquid water distribution in porous layers of an operational Proton Exchange Membrane Fuel Cell (PEMFC) with high spatial and temporal resolution, Laboratory-based soft X-ray microscopy has developed. This system can generate low energy X-ray in the soft X-ray range, and maximum sensitivity towards water is achieved. A point X-ray source with a diameter of less than 1.0 μm and the improved detector optics contribute to realize a spatial resolution of 500 nm and a temporal resolution of 1.0 sec/frame. In addition, in-plane and through-plane observations of an operational PEMFC were carried out. In the in-plane observation test, non-uniform distribution of liquid water in the plane of the catalyst layer was observed, and the importance of appropriate design of the catalyst layer to liquid water transport phenomena was suggested. In the through-plane observation test, liquid water discharge behavior near under the rib area was observed, and the importance of channel wall wettability to liquid water transport phenomena was also suggested.
Validation and Calibration of a Proton Exchange Membrane Fuel Cell Model Against Dynamic Partial Pressure Data
Authors: Roy Arnab , Pasaogullari Ugur , Renfro Michael W. , Cetegen Baki M.
Published: December 2010

Transient experimental validation and investigation of the effect of diffusivity of porous layers on the dynamic water vapor partial pressure profiles of a proton exchange membrane fuel cell (PEMFC) during load change is presented. A three dimensional, isothermal, transient, single-phase computational fluid dynamics based model is developed to validate with the water partial pressure profiles experimentally measured during start-up conditions earlier in a 50 cm2 PEMFC having a single serpentine flow path in counter-flow configuration. The fluid flow within the serpentine channel geometry is simulated using a straight channel fuel cell model with total channel length equivalent to the stretched length of the entire serpentine path incorporating the same amount of pressure drop from inlet to outlet. The model equations are solved using a multi-domain approach incorporating water transport through membrane and multi-component species transport through porous diffusion layer. The transient model predictions of water partial pressure profiles of anode and cathode channels are found to be in good agreement within the error bounds of the experimental results. This validation is also indicative of the two different time scales i.e. initial anode dip due to electro-osmotic drag and recovery due to back diffusion from cathode to anode. Steady state model predictions are compared to check for accuracy simultaneously. The model also delineates the significance of effective diffusivity of porous Gas Diffusion Layers (GDL) and Catalyst Layers (CL) on transient characteristics. In order to come up with best parameters to validate with experimental data, a sensitivity analysis with parametric variations of effective porosity of GDL and CL is performed with a single experimental data set and then applied to the remaining sets. Results show that the CL diffusivity has a more pronounced effect on water accumulation as well as on temporal water transport than GDL diffusivity. The numerical simulation thus provides a validated set of quantitative model parameters along with an insight to the underlying physics of water transport phenomena in a PEMFC.
Thermodynamic Modeling and Energy Analysis of a SOFC-PEMFC Combination in a Gas Turbine Cycle
Authors: Gadalla Mohamed , Al Aid Nabil
Published: December 2010

This paper studies the performance of a hybrid system that comprises a SOFC (Solid-Oxide-Fuel-Cell) combined with a PEMFC (polymer electrolyte membrane fuel Cell) which is integrated into a Gas Turbine power plant. Detailed modeling, thermodynamic, kinetic, geometric models are developed, implemented and validated for the synthesis/design and operational analysis of the combined hybrid system. In this system, the PEMFC makes use of the internal reforming ability of the SOFC to produce hydrogen which is necessary for the PEMFC operation. The heat released in the SOFC is utilized in the internal reforming process. Different levels of modeling for the SOFC, the PEMFC and the integrated system are presented. The overall system performance is analyzed by employing individual models and further applying thermodynamic laws for the entire cycle. The paper also introduces different methods of using shift reactors where CO reacts with H2O to produce CO2 and H2 to further increase the efficiency of the system by introducing a new factor to control parasitic energy consumption. In addition to this, the paper also suggests cooling the H2 stream before entering the PEMFC stack using the exhaust air of the Gas turbine. The main components of the SOFC+PEMFC system are a SOFC stack, shift reactors, selective oxidizer and a PEMFC stack. The fuel cells are connected in series for fuel feeding. Furthermore, although the efficiency of the SOFC increases with increasing operating pressures, the paper describes that the efficiency of the SOFC-PEMFC combination also varies with changing the temperatures. Energy and entropy balances are performed not only for the whole system but also for each component to evaluate the distribution of irreversibility and thermodynamic inefficiencies. According to the study, around 5% efficiency improvement was obtained with a parallel SOFC-PEMFC system as compared with a stand-alone SOFC. Alternative methods of improving the efficiencies are also introduced.
Fuel Cells and Hydrogen Education at Michigan Technological University
Authors: Mukherjee Abhijit , Keith Jason M. , Crowl Daniel A. , Caspary David W. , Allen Jeff , Naber Jeff , Meng Dennis Desheng , Lukowski John , Meldrum Jay , Solomon Barry
Published: December 2010

There is a strong need for a transformative curriculum to train the next generation of engineers who will help design, construct, and operate fuel cell vehicles and the associated hydrogen fueling infrastructure. In this poster we discuss how we integrate fuel cell and hydrogen technology into the project-based, hands-on learning experiences in engineering education at Michigan Technological University. Our approach is to involve students in the learning process via team-based interactive projects with a real-world flavor. This project has resulted in the formation of an “Interdisciplinary Minor in Hydrogen Technology” at Michigan Technological University. To receive the 16 credit minor, students are required to satisfy requirements in four areas, which are: • Participation in multiple semesters of the Alternative Fuels Group Enterprise, where students work on hands-on integration, design, and/or research projects in hydrogen and fuel cells. • Enrolling in a fuel cell course. • Enrolling in a lecture or laboratory course on hydrogen energy. • Enrolling in discipline-specific elective courses.
Fault Tree Analysis Aimed to Design and Implement On-Field Fault Detection and Isolation Schemes for SOFC Systems
Authors: Arsie Ivan , Di Filippi Arturo , Marra Dario , Pianese Cesare , Sorrentino Marco
Published: December 2010

The paper focuses on a methodological study oriented towards the development of diagnostic tools for on-field operating solid oxide fuel cell (SOFC) systems. This work is motivated by the increasing demand for diagnostic techniques aimed at both increasing durability and fully exploiting SOFC benefits throughout system lifetime. Nowadays many SOFC diagnostic applications are available in lab-controlled environment, but few studies are proposed for on-field use. Main contribution of this work is thus the development of suited methodologies for detection and isolation of typical SOFC system faults. Fault tree analysis (FTA) is proposed as a tool for the isolation process. For each specific component, the most significant faults are correlated, via a top-down approach, to the corresponding symptom(s). The knowledge gained through the FTA is exploited to understand the mutual interactions among all devices within the entire SOFC system. Such an approach resulted in the definition of a fault signature matrix that conveniently links system-level symptoms to specific component faults. Such an approach is therefore suitable to perform fault detection and isolation (FDI) of an SOFC system as a whole.
Partial Impedance Spectroscopy Tests of a 6 kW Proton Exchange Membrane Water Electrolyzer Stack
Authors: Han Taehee , Salehfar Hossein , Dale Nilesh V. , Mann Mike D. , Thakare Jivan N.
Published: December 2010

Impedance characteristics of a 6 kW proton exchange membrane (PEM) electrolyzer stack are presented under various operating conditions. An electrolyzer stack was operated under room temperature and partial current range (0 to 80 A). The whole stack impedance spectrums were measured by three different power supply configurations. The total sweeping frequency range (0.5 Hz to 20 kHz) is divided into low frequency (0.5 to 20 Hz), middle frequency (20 Hz to 1 kHz), and high frequency (1 to 20 kHz). Each frequency range required a different measurement setup to measure the whole stack impedance data. In this study, the partial impedance spectrums at low and high frequency ranges are successfully measured and analyzed. The measured data is verified with Kramers-Kronig relations. Measurement issues at the middle frequency region are discussed.
Non-Equilibrium Phase Change in a Proton Exchange Membrane Fuel Cell
Authors: Khajeh-Hosseini-Dalasm N. , Fushinobu Kazuyoshi , Okazaki Ken
Published: December 2010

A three-dimensional steady-state two-phase non-isothermal model which couples the water and thermal management has been developed in order to numerically investigate the spatial distribution of the interfacial mass transfer phase-change rate in the cathode side of a proton exchange membrane fuel cell (PEMFC). A non-equilibrium evaporation-condensation phase change rate is incorporated in the model which allows a supersaturation and undersaturation take place. The differences of non-equilibrium phase and equilibrium assumption inside the gas diffusion layer (GDL) has been addressed by comparing the corresponding liquid saturation and temperature distributions. Regarding water management, the assumption of isothermal model versus the non-isothermal model has been investigated. A parametric study has been also carried out to investigate the effects of operation conditions namely as the channel inlet humidity, cell operating temperature and inlet mass flow rate on the phase-change rate. Since the exact values of the phase change constants for the hydrophobic GDL has not been specified yet, the effects of the phase-change constant on the liquid saturation distribution are demonstrated.
The Yin and Yang of Steroid Hormones in Placental Development
Authors: Bentley-Lewis Rhonda
Published: December 2010

Impaired placental size and function are associated with low aldosterone and high cortisol.
Scar Tactics
Authors: Cheng Elaine
Published: December 2010

Targeted delivery of antifibrotic compounds stems scar formation.
Functional Analysis of VopF Activity Required for Colonization in Vibrio cholerae
Authors: Tam Vincent C. , Suzuki Masato , Coughlin Margaret , Saslowsky David , Biswas Kuntal , Lencer Wayne I. , Faruque Shah M. , Mekalanos John J.
Published: December 2010

Vibrio cholerae
, a Gram-negative facultative pathogen, is the etiologic agent for the diarrheal disease cholera. We previously characterized a clinical isolate, AM-19226, that translocates a type III secretion system (T3SS) effector protein with actin-nucleating activity, VopF, into the host cells. From comparative genomic studies, we identified a divergent T3SS island in additional isolates which possess a VopF homolog, VopN. Unlike the VopF-mediated protrusion formation, VopN localizes to stress fiber in host cells similarly to VopL, which is present in the pandemic strain of
Vibrio parahaemolyticus
. Chimera and yeast two-hybrid studies indicated that the amino-terminal regions of VopF and VopN proteins interact with distinct host cell factors. We determined that AM-19226-infected cells are arrested at S phase of the cell cycle and that VopF/VopN are antiapoptotic factors. To understand how VopF may contribute to the pathogenesis of AM-19226, we examined the effect of VopF in an
in vitro
polarized-epithelial model and an
in vivo
adult rabbit diarrheal model. Within the T3SS pathogenicity island is VopE, a homolog of YopE from
Yersinia
, which has been shown to loosen tight junctions. In polarized intestinal epithelia, VopF and VopE compromised the integrity of tight junctions by inducing cortical actin depolymerization and aberrant localization of the tight-junction protein ZO-1. An assay for pathogenicity in the adult rabbit diarrhea model suggested that these effectors are involved in eliciting the diarrheal response in infected rabbits.

IMPORTANCE
Vibrio cholerae
is a bacterial pathogen that causes the diarrheal disease cholera, which remains a major public health problem in many developing countries. While the major virulence factors of the pandemic
V. cholerae
strains have been characterized, new clinical strains of
V. cholerae
have arisen, causing sporadic cholera-like diseases using unknown pathogenic mechanisms. Previously, we discovered the type III secretion system in a new clinical strain of
V. cholerae
and also identified an effector protein, VopF, which is injected into the host cells and induces changes in the actin cytoskeleton. In this work, we identified a homolog of VopF that causes a distinct cellular phenotype and interactions between the effectors and host proteins. We also discovered that both effectors prevent bacterium-induced cell death in infected cells. In our tissue culture and animal models, we showed that VopF contributes to the disruption of epithelial integrity and the diarrheal response.
Acupuncture Effect on Thermal Tolerance and Electrical Pain Threshold: A Randomised Controlled Trial
Authors: Amand Marc , Nguyen-Huu Florence , Balestra Costantino
Published: December 2010

Objective

The aim of this study was to test whether acupuncture could modify the threshold of tolerance to thermal and electrical stimuli.

Methods

A randomised placebo-controlled single-blind trial was conducted in 36 healthy volunteers randomly distributed to control (no treatment), conventional acupuncture and sham acupuncture groups. The subjects were blind to the group allocation. The authors measured before and after treatment the pain threshold with the Painmatcher (Cefar Medical AB, Lund, Sweden) and the cold tolerance with the cold pressor test, together with the Visual Analogue Scale pain score.

Results

Electrical stimulation threshold and cold pressor tolerance both increased significantly in the control and the true acupuncture groups, but not the sham group. The changes in the true acupuncture group were highly statistically significant and amounted to 24% (pain threshold) and 44% (cold tolerance) increases in threshold. The changes in the true group were significantly greater than the control group but not significantly different from the sham group. The changes in the sham and control groups were not significantly different from each other.

Conclusion

Acupuncture at true, appropriate points was more effective than no intervention in raising pain threshold and tolerance in volunteers, and acupuncture at inappropriate points had an intermediate effect which was not significantly different from either. Thus acupuncture analgesia may not be a point specific effect.
Electronic nicotine delivery systems: is there a need for regulation?
Authors: Trtchounian Anna , Talbot Prue
Published: December 2010

Purpose

Electronic nicotine delivery systems (ENDS) purport to deliver nicotine to the lungs of smokers. Five brands of ENDS were evaluated for design features, accuracy and clarity of labelling and quality of instruction manuals and associated print material supplied with products or on manufacturers' websites.

Methods

ENDS were purchased from online vendors and analysed for various parameters.

Results

While the basic design of ENDS was similar across brands, specific design features varied significantly. Fluid contained in cartridge reservoirs readily leaked out of most brands, and it was difficult to assemble or disassemble ENDS without touching nicotine-containing fluid. Two brands had designs that helped lessen this problem. Labelling of cartridges was very poor; labelling of some cartridge wrappers was better than labelling of cartridges. In general, packs of replacement cartridges were better labelled than the wrappers or cartridges, but most packs lacked cartridge content and warning information, and sometimes packs had confusing information. Used cartridges contained fluid, and disposal of nicotine-containing cartridges was not adequately addressed on websites or in manuals. Orders were sometimes filled incorrectly, and safety features did not always function properly. Print and internet material often contained information or made claims for which there is currently no scientific support.

Conclusions

Design flaws, lack of adequate labelling and concerns about quality control and health issues indicate that regulators should consider removing ENDS from the market until their safety can be adequately evaluated.
Regioselective bromination of palladium tetraphenyltetrabenzoporphyrin to benzo-rings: Synthesis of mono- and octabromotetrabenzoporphyrins and their properties
Authors: Chumakov Denis , Moiseeva Anna , Anisimov Alexander , Uzhinov Boris , Khoroshutin Andrey
Published: December 2010

Bromination of palladium meso-tetraphenyl tetrabenzoporphyrin ( Pd Ph4TBP, 1) by Me4NBr3 or Me4NBr/Br2 was shown to proceed regioselectively to the benzo-rings annelated to main porphyrin macrocycle. Conditions for preferential mono- and octa-bromination have been established. The respective mono- and octa-bromide ( Pd Ph4TBP( Br ), 2 and Pd Ph4TBP( Br )8, 3) have been isolated and characterized by UV-vis, NMR and LDI-TOF spectroscopy. Changes of electrochemical properties of tetrabenzoporphyrins induced by Br atoms were found to follow the same trends as the changes in analogous non-extended porphyrins. Room temperature phosphorescence is not substantially influenced by the substitution.
Preparation and characterization of novel magnetic nanocomposite-bonded metalloporphyrins as biomimetic nanocatalysts
Authors: Liu Chang-Xiang , Liu Qiang , Guo Can-Cheng , Tan Ze
Published: December 2010

In this work, novel magnetic nanocomposite-bonded metalloporphyrins were synthesized by an effective silanation approach between 3-aminopropyltriethoxysilane derivatized metalloporphyrins and silica-coated magnetic Fe3O4 nanoparticles. The initial metalloporphyrin derivatives were synthesized by the amidation reaction of metalloporphyrin acyl chloride with 3-aminopropyltriethoxysilane. After the metalloporphyrin derivatives were adsorbed on the surface of silica-coated magnetic Fe3O4 nanoparticles, the solid mixture was heated under vacuum at 110 °C for 3 h and then thoroughly washed with chloroform. The obtained magnetic nanocomposite-bonded metalloporphyrins were characterized by elemental analyzer, low-temperature N2 adsorption (BET method), transmission electron microscopy, UV-vis spectroscopy, and infrared spectroscopy. Interestingly, using this particular silanation method, metalloporphyrins could be quantitative-immobilized in magnetic nanocomposites by controlling the input ratio of metalloporphyrins and silica-coated magnetic Fe3O4 nanoparticles. The excellent catalytic activity and recyclability of the magnetic nanocomposite-bonded metalloporphyrins were demonstrated in the cyclohexane oxidation with iodosylbenzene.
Porphyrins and phthalocyanines in solar photovoltaic cells
Authors: Walter Michael G. , Rudine Alexander B. , Wamser Carl C.
Published: December 2010

This review summarizes recent advances in the use of porphyrins, phthalocyanines, and related compounds as components of solar cells, including organic molecular solar cells, polymer cells, anddye-sensitized solar cells. The recent report of a porphyrin dye that achieves 11% power conversion efficiency in a dye-sensitized solar cell indicates that these classes of compounds can be as efficient as the more commonly used ruthenium bipyridyl derivatives.
PERSONAL CHARACTERISTICS OF INNOVATORS — AN EMPIRICAL STUDY OF ROLES IN INNOVATION MANAGEMENT
Authors: MANSFELD MARTINA N. , HÖLZLE KATHARINA , GEMÜNDEN HANS GEORG
Published: December 2010

First and foremost, innovation is driven by people. These people have specific personal characteristics and fulfil designated roles in innovation management. We have conducted an empirical study among 190 employees in R&D departments of mature international firms from four different countries (Germany, U.S.A., Great Britain and Switzerland) currently working on innovation projects. Using multivariate analyses, we could identify personal characteristics associated with different roles people can take over the course of an innovation project. These roles are called expert, power, process or relationship promotor as well as champion. The identified personal characteristics exhibit a distinctive pattern in their combined occurrence for each role. Our results show a detailed picture of specific personal characteristics of individuals, so called innovators, necessary for successful innovation. Based on these findings, we derive recommendations for a targeted human resource acquisition and a better selection of employees for successful innovation teams.
IMPLEMENTING A VALUE ASSESSMENT TOOL FOR SERVICE INNOVATION IDEAS
Authors: AAS TOR HELGE
Published: December 2010

There has not been much discussion of how firms may assess the value of service innovation projects ex-ante in the extant research literature. This paper theoretically derives a value assessment tool for service innovation ideas called QSI (tool for pre-Qualification of Service Innovation projects). Thereafter QSI is implemented in three firms and it is explored to what degree the implementation improved managerial decision making on service innovation projects and investments. The findings indicated that the implementation of QSI had effects both in a portfolio management and a project management perspective. From a portfolio management point of view deployment of QSI improved the participating managers' decision basis for prioritizing and selection of projects. From a project management point of view implementation of QSI enabled the participating managers to define more relevant, realistic and ambitious targets for service innovation projects than they were able to define without deploying the tool.
Compound deletion of Fgfr3 and Fgfr4 partially rescues the Hyp mouse phenotype
Authors: Li Hua , Martin Aline , David Valentin , Quarles L. Darryl
Published: December 2010

Uncertainty exists regarding the physiologically relevant fibroblast growth factor (FGF) receptor (FGFR) for FGF23 in the kidney and the precise tubular segments that are targeted by FGF23. Current data suggest that FGF23 targets the FGFR1c-Klotho complex to coordinately regulate phosphate transport and 1,25-dihydroxyvitamin D [1,25(OH)2D] production in the proximal tubule. In studies using the Hyp mouse model, which displays FGF23-mediated hypophosphatemia and aberrant vitamin D, deletion of Fgfr3 or Fgfr4 alone failed to correct the Hyp phenotype. To determine whether FGFR1 is sufficient to mediate the renal effects of FGF23, we deleted Fgfr3 and Fgfr4 in Hyp mice, leaving intact the FGFR1 pathway by transferring compound Fgfr3/Fgfr4-null mice on the Hyp background to create wild-type (WT), Hyp, Fgfr3−/−/Fgfr4−/−, and Hyp/Fgfr3−/−/Fgfr4−/−mice. We found that deletion of Fgfr3 and Fgfr4 in Fgfr3−/−/Fgfr4−/−and Hyp/Fgfr3−/−/Fgfr4−/−mice induced an increase in 1,25(OH)2D. In Hyp/Fgfr3−/−/Fgfr4−/−mice, it partially corrected the hypophosphatemia (Pi= 9.4 ± 0.9, 6.1 ± 0.2, 9.1 ± 0.4, and 8.0 ± 0.5 mg/dl in WT, Hyp, Fgfr3−/−/Fgfr4−/−, and Hyp/Fgfr3−/−/Fgfr4−/−mice, respectively), increased Na-phosphate cotransporter Napi2a and Napi2c and Klotho mRNA expression in the kidney, and markedly increased serum FGF23 levels (107 ± 20, 3,680 ± 284, 167 ± 22, and 18,492 ± 1,547 pg/ml in WT, Hyp, Fgfr3−/−/Fgfr4−/−, and Hyp/Fgfr3−/−/Fgfr4−/−mice, respectively), consistent with a compensatory response to the induction of end-organ resistance. Fgfr1 expression was unchanged in Hyp/Fgfr3−/−/Fgfr4−/−mice and was not sufficient to transduce the full effects of FGF23 in Hyp/Fgfr3−/−/Fgfr4−/−mice. These studies suggest that FGFR1, FGFR3, and FGFR4 act in concert to mediate FGF23 effects on the kidney and that loss of FGFR function leads to feedback stimulation of Fgf23 expression in bone.
Cardiomyocyte lipids impair β-adrenergic receptor function via PKC activation
Authors: Drosatos Konstantinos , Bharadwaj Kalyani G. , Lymperopoulos Anastasios , Ikeda Shota , Khan Raffay , Hu Yunying , Agarwal Rajiv , Yu Shuiqing , Jiang Hongfeng , Steinberg Susan F. , Blaner William S. , Koch Walter J. , Goldberg Ira J.
Published: December 2010

Normal hearts have increased contractility in response to catecholamines. Because several lipids activate PKCs, we hypothesized that excess cellular lipids would inhibit cardiomyocyte responsiveness to adrenergic stimuli. Cardiomyocytes treated with saturated free fatty acids, ceramide, and diacylglycerol had reduced cellular cAMP response to isoproterenol. This was associated with increased PKC activation and reduction of β-adrenergic receptor (β-AR) density. Pharmacological and genetic PKC inhibition prevented both palmitate-induced β-AR insensitivity and the accompanying reduction in cell surface β-ARs. Mice with excess lipid uptake due to either cardiac-specific overexpression of anchored lipoprotein lipase, PPARγ, or acyl-CoA synthetase-1 or high-fat diet showed reduced inotropic responsiveness to dobutamine. This was associated with activation of protein kinase C (PKC)α or PKCδ. Thus, several lipids that are increased in the setting of lipotoxicity can produce abnormalities in β-AR responsiveness. This can be attributed to PKC activation and reduced β-AR levels.