bluuebunny/crossref_metadata_2025 huggingface dataset:
Genets of Typhula ishikariensis biotype A belonging to a vegetative compatibility group
Authors: Matsumoto Naoyuki , Tsushima Selya , Uchiyama Kazuko
Published: May 2008

Vegetative compatibility groups of Typhula ishikariensis biotype A include different isolates from various localities, and the most prevalent one (super vegetative compatibility group) was studied to reveal that this super group consisted of several genets existing throughout the habitat of T. ishikariensis biotype A in Hokkaido, Japan. Random amplified polymorphic DNA and mating incompatibility alleles were studied for 10 isolates belonging to the super vegetative compatibility group from two localities 250 km distant from each other and for five isolates belonging to different groups. Seven primers, which distinguished vegetative compatibility groups, were screened out of 60 and produced a total of 55 bands. The 10 super group isolates were divided into 5 subgroups, and the five unique isolates did not cluster with each other. Protoplasts were produced from each isolate to obtain monokaryons. They were then mated with tester monokaryons derived from basidiospores of two parental isolates, one of which belonged to the super vegetative compatibility group. Mating patterns suggested that the 10 super group isolates shared common mating incompatibility alleles but this was not the case with those belonging to unique groups. The super vegetative compatibility group was found to consist of several genets with many ramets distributed throughout the habitat of T. ishikariensis biotype A in Hokkaido. These genets were regarded as sib-related dikaryons derived from basidiospores. Keywords: Typhula ishikariensis, snow mold, genet, RAPD, mating incompatibility.
Staminate floral development in Begonia cucullata var. hookeri and three double-flowering begonia cultivars, examples of homeosis
Authors: Lehmann Nalda L. , Sattler Rolf
Published: May 2008

Homeosis is a process whereby features characteristic of one structure are found in the position that a different structure normally occupies. In three double-flowering begonia cultivars, perianth features are expressed in the positions stamens occupy in a single-flowering begonia. The staminate flower of Begonia cucullata var. hookeri (Willd.) consists of two broad sepals, two small petals in a more or less decussate arrangement, and an androecium of numerous stamens. The staminate flowers of Begonia semperflorens-cultorum ‘Cinderella’, ‘Goldie Locks’, and ‘Lucy Lockett’ also have a perianth of two sepals and two petals, but sepaloid and petaloid appendages form in positions that stamens occupy in the single-flowered progenitor. Using epi-iilumination microscopy, we found that early stages of floral development in the double-flowering cultivars are similar to the early stages of development in the single-flowered begonia, while later stages diverge remarkably. The first primordia that will form petaloid appendages are small and round at the time of initiation, similar in appearance and position to those primordia that become stamens in the single-flowered begonia. As these primordia develop, they broaden and flatten, forming perianth-like appendages. Keywords: homeosis, begonia, double flower, floral development.
Fungi on Juncus roemerianus. 8. New bitunicate ascomycetes
Authors: Kohlmeyer Jan , Volkmann-Kohlmeyer Brigitte , Eriksson Ove E.
Published: May 2008

Heleiosa barbatula gen. et sp.nov., Massariosphaeria erucacea sp.nov., and Scirrhia annulata sp.nov. are described from Juncus roemerianus in salt marshes of the United States east coast. Whereas H. barbatula is very rare, the other two species do not show a seasonality because they occurred in almost every one of the monthly collections made throughout 2 years. The new genus Heleiosa is of unknown affinity but may belong to Dothideales s.l. Keywords: ascomycetes, Heleiosa, Juncus, Massariosphaeria, salt marsh, Scirrhia.
Bearing capacity of flexible piles under eccentric and inclined loads in layered soil
Authors: Yalcin A. S. , Meyerhof G. G.
Published: May 2008

The bearing capacity of flexible model piles and small pile groups under axial, lateral, and various combinations of eccentric and inclined loads in layered soil consisting of clay overlying sand is investigated. Ultimate pile capacity is found to depend on the eccentricity and inclination of the load and, more significantly, on the ratio of the upper layer thickness to pile embedment. Theoretical estimates based on the concept of effective pile embedment ratio and expressed in terms of equivalent rigid piles agree reasonably well with the experimental values. The behaviour of 2 × 2 flexible model pile groups is observed to be similar to that of single piles. Key words: bearing capacity, piles, flexible pile, pile group, layered soil, sand, clay, eccentric load, inclined load, model pile test.
Liquefaction resistance of cemented sands under multidirectional cyclic loading
Authors: Reddy Krishna R. , Saxena Surendra K.
Published: May 2008

This paper presents a methodology to predict liquefaction of uncemented and cemented sands under multidirectional cyclic loading conditions using solely conventional unidirectional cyclic test data. The method is found to be reasonably accurate based on the reported multidirectional cyclic test results using a true triaxial apparatus. Key words : sand, cementation, triaxial, experimental, theoretical, liquefaction.
Effective stress and water pressure in saturated clays during heating–cooling cycles
Authors: Hueckel T. , Pellegrini R.
Published: May 2008

Experiments with heating and cooling cycles in undrained constant total stress conditions in triaxial apparatus are presented. Heating induces a large pore-water pressure increase, which eventually leads to a large irreversible strain and possible mechanical failure. Subsequent cooling produces a drop in water pressure. In one test the drop during cooling was more than two times higher than the previous increase during heating, reaching values of up to 2.30 MPa. An analysis of these findings in terms of a thermoplastic model is presented. The interpretation of these tests relies heavily on the kind of stress-partitioning hypothesis that is used. It was found that the described phenomena can be quantitatively dealt with using the classical effective stress principle, if the shear strength and consolidation are described in terms of temperature-dependent plastic yield limit. Key words : temperature, plastic strains, effective stress, pore pressure.
Centrifuge modeling of geotextile-reinforced steep clay slopes
Authors: Porbaha A , Goodings D J
Published: May 2008

When on-site soil is not granular, substantial cost savings can be achieved if a stable, steeply sloped, reinforced retaining system, backfilled with on-site fill can be sustituted for a vertical retaining wall with granular fill. Centrifuge modeling was used in this work to investigate the failure and prefailure behaviour of 14 reduced-scale geotextile-reinforced steep model slopes of 45, 63.4, 71.6°, backfilled with cohesive soil and constructed on either firm or rigid foundations. The overall performance of model slopes on firm foundations was found to be better than that of similar models on rigid foundations. A stability analysis, using the Bishop simplified method incorporating reinforcement, was found to be a good predictor of the behaviour of models.

Key words: reinforced soil, centrifuge modeling, geotextile, retaining structure, slope stability.
Effects of freezing and thawing on the hydraulic conductivity of paper mill sludges used as landfill covers
Authors: Moo-Young, Jr. Horace K , Zimmie Thomas F
Published: May 2008

A major concern in the design of landfill covers and liners that use compacted clays as the hydraulic barrier is freezing and thawing. Paper mill sludges have been used in landfill covers to subtitute for clays as the hydraulic barrier. In this study, laboratory-compacted paper sludges have been subjected to one-dimensional and three-dimensional laboratory freezing and thawing cycles. Freezing and thawing increased the hydraulic conductivity of the paper sludges about one to two orders of magnitude. To determine why freezing and thawing cause an increase in hydraulic conductivity, an evaluation of the effects of freezing and thawing on the macrostucture of paper sludges was conducted. Frozen thin sections of paper sludges were prepared after freezethaw cycling and were compared to frozen thin sections of a compacted clay. Macrostructure analysis of the paper sludge and clay thin sections was conducted by using back lighting to reveal the details of ice structure. Analysis of the clay thin sections revealed ice lenses and shrinkage cracks. Ice lenses and shrinkage cracks in sludge thin sections were difficult to determine when the same procedure for compacted clays was used.

Key words: freeze, paper sludge, landfill, permeability, macrostructure, thin sections.
Swelling behaviour of soilbentonite mixtures
Authors: Sivapullaiah P V , Sridharan A , Stalin V K
Published: May 2008

Studies on the swelling behaviour of mixtures of bentonite clay and nonswelling coarser fractions of different sizes and shapes reveal that observed swelling occurs only after the voids of the nonswelling particles are filled up with swollen clay particles. The magnitude of the swell within the voids, called intervoid swelling is large when the size and percentage of the nonswelling coarser fraction is large. The observable swell, after intervoid swelling, is called primary swelling and follows a rectangular hyperbolic realtionship with time. The total swell per gram of the clay decreases with an increase in the size of the nonswelling fraction and with a decrease in the percentage of swelling clay. Timeswell realionships show that swelling continues to occur for a long time after the primary swelling, and this is called secondary swelling.

Key words: clay, expansive soil, swelling, time factor.
A study on the behaviour of soilgeotextile systems in filtration tests
Authors: Palmeira E M , Fannin R J , Vaid Y P
Published: May 2008

The behaviour of soilgeotextile systems in filtration tests is reported for nonwoven geotextiles under unidirectional flow. A new apparatus was developed to preform filtration tests under an applied vertical stress, and tests were then conducted with different soils and nonwoven geotextiles in order to evaluate the clogging potential and retention capacity of these materials under rather severe combinations of geotextile and soil characteristics. Results show that the geotextiles perfomed well and that observed permeability losses were acceptable even for gradient ratios close to 3. No progressive piping was observed, and it is believed that the retention capacity of the geotextiles may be influenced by their manufacturing process. In general, theoretical predictions for the maximum particle size passing through the geotextile compared well with measurements.

Key words: geotextiles, filtration, gradient ratio, permeability, soil retention, clogging.
Rigid pile with a baseplate under large moments: laboratory model evaluations
Authors: Prasad Yenumula VSN , Chari T R
Published: May 2008

Results of tests on a rigid embedded pile with baseplate are presented. Laboratory tests were conducted with an instrumented 102 mm rigid circular pile embedded in sand and subjected to combined moment and horizontal load. Two different backfills and two different baseplates were used. The rotation of pile and the soil pressure distributions along the length of the pile and at the bottom of the baseplate were measured. It was found that the moment carrying capacity of a rigid pile can be increased between 25 and 50% by using a baseplate. The investigations reported in this paper are useful in the design of directly embedded transmission-pole foundations.

Key words:baseplate, model tests, rigid pile, sand, transmission poles, ultimate moment.
The prediction and distribution of general yield classes of Sitka spruce in Scotland by empirical analysis of site factors using a geographic information system
Authors: Allison S.M. , Proe M.F. , Matthews K.B.
Published: May 2008

A framework has been developed to predict growth of Sitka spruce (Piceasitchensis (Bong.) Carr.) at a regional scale throughout Scotland based on an analysis of yield, site, and climatic factors. Using the general yield class (GYC) system for predicting forest production (m3•ha−1•year−1), the statistical model was integrated with a geographic information system to predict tree growth at a resolution of 1 km2. Site factor data from 487 sample sites were analysed along with the associated climate data derived from monthly 30-year means recorded at meteorological stations throughout the country. Multiple regression was used to develop and validate the model, which accounted for 59% of the variation in observed GYC. Standard errors of prediction were determined by analysis of variance to provide confidence limits for the 1-km2 GYC predictions. The distribution of these estimates of production was plotted in the form of a digital map for Scotland, housed within the geographic information system and providing a facility to readily analyse and summarise regional information.
Black stem galls on aspen and their relationship to decay by Phellinustremulae
Authors: Crane Patricia E. , Blenis P.V. , Hiratsuka Y.
Published: May 2008

Efficient use of trembling aspen (Populustremuloides Michx.) is often limited by the presence of extensive decay and stain. Aspen trees with black stem galls of unknown cause reportedly have less advanced decay caused by the fungus Phellinustremulae (Bond.) Bond. & Boriss. than do adjacent trees without galls. Nine field sites having large numbers of galled aspen were surveyed for the presence of P. tremulae conks. Logistic regression showed that the odds of a gall tree having at least one conk was 44% of that for trees without galls, and that the occurrence of conks varied among sites and increased with increasing tree diameter. Inclusion of black galls in models used to predict decay might result in greater accuracy on sites where these galls are prevalent. Black galls may also be potential sources of biological control agents against decay-causing organisms in aspen.
Foliage area–sapwood area relationships of Scots pine (Pinussylvestris) trees in different climates
Authors: Berninger Frank , Nikinmaa Eero
Published: May 2008

Foliage mass and wood cross-sectional area were measured at different points of branches and stems within the living crown of Scots pine (Pinussylvestris L.) trees from sample plots, representing wide geographical variation. The measurements were taken during the period of annual minimum foliage mass. The needle mass: branch cross-sectional area ratio, measured below the lowest living whorl of sub-branches, differed among measured points and was normally lower for the uppermost branches, but also decreased in the lower canopy. The decrease at the lower canopy was hypothesized to reflect an excess water transport capacity resulting from the senesced needles. The lower ratio in the uppermost branches might be explained by M.H. Zimmermann's hypothesis that the water supply of foliage close to the stem is preferred. A similar trend in the branch area: stem area ratio was observed along the stem. There seemed to be strong geographic variation in the ratio between the total cross-sectional area of branches of the crown measured and the stem cross-sectional area below the living crown. The branch area: stem area ratio was higher in the southern stands, whereas there was no clear trend for the needle area: branch area ratio. The results are discussed in relation to the hydraulic architecture of trees.
A BACK-REACTION INDUCED LOWER BOUND ON THE TENSOR-TO-SCALAR RATIO
Authors: MARTINEAU PATRICK , BRANDENBERGER ROBERT
Published: May 2008

There are large classes of inflationary models, particularly popular in the context of string theory and braneworld approaches to inflation, in which the ratio of linearized tensor-to-scalar metric fluctuations is very small. In such models, however, gravitational waves produced by scalar modes cannot be neglected. We derive the lower bound on the tensor-to-scalar ratio by considering the back-reaction of the scalar perturbations as a source of gravitational waves. These results show that no cosmological model that is compatible with a metric scalar amplitude of ≈10-5 can have a ratio of the tensor-to-scalar power spectra less than ≈10-8 at recombination and that higher-order terms leads to logarithmic growth for r during radiation domination. Our lower bound also applies to non-inflationary models which produce an almost scale-invariant spectrum of coherent super-Hubble scale metric fluctuations.
OUTLINE OF THE SECOQC QUANTUM-KEY-DISTRIBUTION NETWORK IN VIENNA
Authors: POPPE A. , PEEV M. , MAURHART O.
Published: May 2008

A quantum key distribution (QKD) network is currently being implemented in Vienna by integrating seven QKD-link devices that connect five subsidiaries of Siemens Austria. We give an architectural overview of the network and present the enabling QKD technologies, as well as the novel QKD network protocols.
QUANTUM COMPUTATION TREE LOGIC — MODEL CHECKING AND COMPLETE CALCULUS
Authors: BALTAZAR P. , CHADHA R. , MATEUS P.
Published: May 2008

Logics for reasoning about quantum states and their evolution have been given in the literature. In this paper, we consider quantum computation tree logic (QCTL), which adds temporal modalities to exogenous quantum propositional logic. We give a sound and complete axiomatization of QCTL and combine the standard CTL model-checking algorithm with the dEQPL model-checking algorithm to obtain a model-checking algorithm for QCTL. Finally, we illustrate the use of the logic by reasoning about the BB84 key distribution protocol.
Novel VHT-PEFC MEAs Based on ABPBI Membranes for APU Applications
Authors: Wannek Christoph , Dohle Hendrik , Mergel Jürgen , Stolten Detlef
Published: May 2008

The performance of poly(2,5-benzimidazole) (ab-PBI or ABPBI; 'AB' reflects the fact that the polybenzimidazole is formed in head-tail variety) membrane based membrane electrode assemblies (MEA) for use as very high temperature PEFCs (T = 160 - 180 {degree sign}C) is reported here. In view of the possible future application of this special type of fuel cell - e.g. in auxiliary power units (APU) in trucks or airplanes - these MEAs have been tested with a six-component gas mixture simulating the composition of a fuel gas produced by autothermal reforming of middle distillates such as diesel or kerosene after the shift reaction. The cell performances with hydrogen and synthetic reformate at different operating temperatures of the fuel cell and thus their 'CO tolerances' are presented and discussed. MEAs with an active area of 46 cm2 have been operated successfully in a prototype 10-cell stack with novel modular design.
Electrical Characterization of GDL Materials for Polymer Fuel Cells (PEMFC)
Authors: Fracas Paolo , Grassini Paolo , Dotelli Giovanni , Gallo Stampino Paola , Brivio Davide
Published: May 2008

A gas diffusion layer (GDL) in a Polymer Fuel Cell (PEMFC) has several important functionalities such as water management, uniform transport of reactant gases, gas permeability, mechanical support and compressibility, electrical and thermal conductivity both in-plane and through-plane. All these requirements are best met by carbon fiber-based materials such as carbon fiber paper, or simply a felt-like material or woven carbon fabrics. In this work, the attention is focused on a new series of GDL materials which were realized by an Italian industry, SAATIgroup. In particular, the attention was focused on two different surface treatments in order to make the GDLs samples hydrophobic. Three different kinds of samples were tested: a first sample with a coating of PTFE, a second sample with a plasma treatment and the third one without any surface treatment.
Operation of Polymer Electrolyte Membrane fuel cells with dry feeds
Authors: Benziger Jay B. , Hogarth Warren H. , Woo Claire
Published: May 2008

Operation of polymer electrolyte membrane fuel cells (PEMFCs) with dry feeds is demonstrated to depend on the gas flow field design, gas pressure, temperature and flow rate. We demonstrate auto-humidified operation of the channel-less, self-draining fuel cell, from 25 to 115ºC. Traditional serpentine flow channel designs cannot sustain autohumidified operation above 60ºC. Auto-humidified (or self humidifying) PEMFC operation is improved in the channel-less fuel cell where axial dispersion enhances "back-mixing" of the product water with the dry feed. The auto-humidified self-draining fuel cell design offers substantial benefits for simplicity of operation and control including: the ability to self drain reducing flooding, the ability to uniformly disperse water removing current gradients and the ability to operate on dry feeds eliminating the need for humidifiers.
The Performance of Monolithic Hybrid Direct Methanol Fuel Cell
Authors: Wang Yang , Zheng Jim P. , Au George , Plichta Edward J.
Published: May 2008

A novel resistive-capacitive-inductive transmission-line equivalent circuit was used to model a direct methanol fuel cell (DMFC). This fuel cell model was developed and improved from existing impedance fuel cell model and transmission-line fuel cell model. The resistive-capacitive-inductive transmission line model can properly describe the inductive and capacitive behaviors of the DMFC operating in both low and high frequency regions. The advantages of this transmission line fuel cell model have been discussed based on Mueller's experimental impedance spectrum of DMFC (1). Finally, the model has been used to estimate the optimum capacitive materials loading in the monolithic hybrid DMFC (2). The numerical simulation proved that increasing double-layer capacitance of the DMFC can provide a good dynamic performance similar to the DMFC connected with a discrete supercapacitor in parallel.
Methanol Oxidation at Pt-Ru-C ternary Electrode Prepared by co-sputtering Technique
Authors: Matsumoto Yosuke , Horii Kota , Nagai Kazuhiro , Umeda Minoru , Usui Yuma , Tanaka Shohji
Published: May 2008

This report describes a Pt-Ru-C electrode prepared by a co-sputtering technique for use as the anode catalyst in direct methanol fuel cells. The 50-100-nm thick electrocatalyst layer was prepared on an Au foil substrate. From the X-ray diffractometer (XRD) measurements, it was determined that (1) Pt and Ru are compatible and (2) Pt and C are incompatible in the Pt-Ru-C electrodes. Based on the results of the background cyclic voltammograms (CVs), the addition of C to the Pt and Pt-Ru causes an increase in the electrochemical surface area. The CVs support the XRD data that Pt and Ru form an alloy. For the methanol oxidation, the Pt72Ru23C5 electrode showed the highest current density and negative onset potential. It was also determined that the Pt-Ru-C containing 5-25 at.% C causes a negative shift in the onset potential for the methanol oxidation.
A Nb-Doped TiO2 Electrocatalyst for Use in Direct Methanol Fuel Cells
Authors: Fuentes Roderick E. , Garcia Brenda L. , Weidner John W.
Published: May 2008

Niobium doped Titanium Dioxide was synthesized using two sol-gel procedures. The first method is characterized for a solvent extraction and a drying step at 100 {degree sign}C. The second, an extraction using ammonium hydroxide is performed followed by calcination at 400 {degree sign}C. X-Ray Diffraction studies shows an improved crystalline structure for the second procedure and BET surface area analysis gives an increase of 33% in surface area over the first procedure. X-Ray Photoelectron spectra identify the low conductivity of the material in the valence-region band and determine oxidation states of 4+ for Titanium and 5+ for Niobium. Colloidal Synthesis method was improved for PtRu catalyst and resulted in higher performance registered in Cyclic Voltammetry experiments. This indicates that improving our synthesis methods we can increase catalytic activity and be comparable with commercial catalysts supported on carbon. The electrochemical results demonstrate the enhancing effect for methanol oxidation of Nb doped Titania supports.
Fabrication of Graphite Composite Bipolar Plates for PEFC Using Polysulfone
Authors: Kim Shinho , Yang Tae-Hyun , Lee Won-Yong , Kim Chang-Soo , Lee Dokyol
Published: May 2008

Bipolar plate is one of the important components in polymer electrolyte fuel cells(PEFCs). A study on the fabrication of bipolar plate using polysulfone(PS) has been conducted. PS has better thermal stability than other thermosetting resins because it has a higher melting point and mechanical strength. The molding temperature is a crucial factor for the fabrication of bipolar plates using PS. The bipolar plates with 20wt.% PS were fabricated at molding temperature range of 200 degree and 320 degree under 39.2MPa. Their flexural strength, sheet resistance and through-plane resistance increased with the high molding themerature up to 290 drgree. The flexural strength was over 56.8MPa, through-plane resistivity was 0.53mohm-m at 290 degree. The cross-sectional image of bipolar plate showed that PS was well penetrated into graphite powders.
Thermal Stability of Portable Micro-Tubular Solid Oxide Fuel Cell and Stack
Authors: Du Yanhai , Finnerty Caine , Jiang Juan
Published: May 2008

Rapid start-up times are a big challenge for high temperature fuel cells such as solid oxide fuel cells (SOFCs), especially large-sized stacks with high power outputs. This paper presents the development of tubular and micro-tubular anode-supported SOFCs and the design and testing of the thermal stability of such single cells and stacks. It was demonstrated that single cells with various sizes have very good thermal shock resistance. Preliminary results also showed that stacks can be started up within minutes and withstand more than 50 thermal cycles and temperature changes of 550oC/min. Several factors that affect the thermal stability are discussed.
Development of Several kW SOFC System using Segmented-cells
Authors: Amaha Shinji , Sobue Tsutomu , Seyama Takehiro
Published: May 2008

In this paper we present recent results of developments for segmented-in-series SOFCs at Tokyo gas. We have been developing segmented-in-series SOFCs for several years. The segmented-cell is a unique idea of eliminating the cell stacking process in assembling processes. For high performance of an SOFC system with the segmented-cells, the cell configuration must be designed optimally and a DC module must be devised to draw the potential of the segmented-cell. In addition, to obtain higher conversion efficiency for the AC system using the segmented-cells, the DC/AC conversion efficiency of the power conditioner should be improved and the energy consumption of the BOP must be reduced. By improving the DC module, developing the power conditioner with a high DC/AC conversion efficiency and reducing the BOP loss, the high net conversion efficiency of the system was achieve
Regression Models Analysis and Optimization of a SOFC SFC 5 kWe Field Unit
Authors: Gariglio Marcello , Santarelli Masimo , De Benedictis Ferrante , Calì Michele , Orsello Gianmichele , Disegna Giovanni
Published: May 2008

The EOS Project carries on an industrial research on Stationary Fuel Cells based on the SOFC technology developed by Siemens Power Generation Stationary Fuel Cells, through a co-operation between TurboCare S.p.A. (a subsidiary of Siemens Power Generation) and Politecnico di Torino. Two SOFC units have been installed and are currently in operation in the TurboCare workshop. The CHP100 generator was commissioned on June 19, 2005, and to date has shown more than 36,000 operating hours at this scale (record availability of 99.5%); the SFC5 alpha6 Generator is in operation since more than 7,000 hours. In the paper the performance of the 5 kW generator are analyzed. First, we have made two experimental analysis of the main variables of the generator with perturbation of the fuel utilization, the generator temperature and the management of the air distribution. Then, the regression models, obtained from the first test campaign and describing the behaviour of the generator, have been used to optimize the system.
Internal Reforming of Hydrocarbon Fuels in Tubular Solid Oxide Fuel Cells
Authors: Cheekatamarla P. K. , Finnerty Caine , Cai J
Published: May 2008

The application of heterogeneous catalysis has an important role to play in the successful commercial development of solid oxide fuel cell (SOFC) technology. In this paper, we present a solid oxide fuel cell that combines a catalyst layer with a conventional anode, allowing internal reforming via partial oxidation (POX) of fuels such as methane, propane, butane, biomass gas etc. without coking and yielding stable power output. The catalyst layer is fabricated on the anode simply by catalyst support coating and reforming catalyst impregnation. The composition and microstructure of catalyst support layer as well as the catalyst composition was easily tailored to meet the demand of in-situ reforming. The usage of catalyst layer as an integrated part of the traditional SOFC will provide a simple low-cost power generating system at substantially higher fuel efficiency and faster start-ups, and may accelerate the application of SOFCs through the direct use of hydrocarbon fuels.
Demonstration of a Pilot-Scale Membrane Reactor Process for Hydrogen Production
Authors: Damle Ashok , Richardson Carrie , Powers Tony , Love Chuck , Acquaviva Jim
Published: May 2008

High performance, high-temperature hydrogen separation membranes represent a key enabling technology for efficient hydrogen production using synthesis gas derived from a variety of feedstocks. RTI International and Pall Corporation are developing high flux and selectivity hydrogen separation membranes by depositing thin Pd-alloy films on tubular ceramic/porous stainless steel composite substrates. Both the plating parameters and the inorganic substrate characteristics are being optimized for high hydrogen selectivity and membrane flux. The developmental Pd-alloy composite membranes were used in a membrane reactor configuration in a pilot-scale module for demonstrating water gas shift (WGS) reaction with simultaneous hydrogen separation producing high purity hydrogen from simulated synthesis gas. Substantially increased CO conversion was observed because of simultaneous hydrogen separation as predicted by membrane reactor model. Greater than 80% of maximum possible hydrogen was recovered in the product stream in membrane reactor operations at 375 and 550oC temperature and 100 and 150 psig pressure.
Modeling and Control Latitude Analysis of a Fuel Cell Anode Tail-gas Oxidizer
Authors: Shi Ruijir , Ou Jing , Zhou Zhi , Rohr Donald F.
Published: May 2008

In this paper, we will discuss the dynamic modeling, reactor analysis and controls development for an anode tail-gas oxidizer (ATO) for a hydrocarbon (e.g. natural gas, LPG, butane etc.) based fuel cell system. The ATO provides three major important functions to the complete system: 1. it generates high quality heat (500 {degree sign}C - 700 {degree sign}C); 2. it integrates this heat back into the system to generate steam; and 3. it minimizes the emissions of methane (CH4) and carbon monoxide (CO) in low cost highly integrated hydrocarbon-based fuel cell systems. The control of the ATO is both important and challenging. Not only does the ATO need to accomplish the previously mentioned functions within a temperature window imposed by the catalyst, but the ATO is also subject to numerous known and unknown disturbances and it exhibits challenging dynamics resulting from thermal time delays and inverse temperature responses. This paper illustrates the use of AspenDynamics® and Simulink® models to evaluate the ATO dynamic response to various disturbances. The ATO response was calculated with a dynamic model and the transient analysis and controls assessment were developed in Simulink®. Control latitudes were studied under electric load conditions ranging from 10% to 90% rated power. In addition, instantaneous load reductions were evaluated to determine control latitude.
A Modular Fuel Cell, Modular DC-DC Converter Concept for High Performance and Enhanced Reliability
Authors: Palma Leonardo M. , Enjeti Prasad N.
Published: May 2008

Bad or mal performing cells in a fuel cell stack cause uneven heat distribution and reduced terminal voltage. As a consequence the overall output power of the system is reduced. Moreover continuous operation under these conditions may not be possible due to excessive heat generation in underperforming cells. In this paper a modular fuel cell powered by a modular DC-DC converter is proposed. This approach electrically divides the fuel cell stack into various sections, each powered by a DC-DC converter, allowing loading each section in the stack according to its state. That is better performing sections handle more load than underperforming sections while the output voltage of the system is kept regulated. In addition the proposed approach can bypass mal-functioning sections while the rest of the stack can continue operation, thus improving the reliability of the system. Experimental results on a 150W prototype confirm the benefits of the proposed approach.
Stationary DFC® Power Plants Status
Authors: Leo Anthony , Brdar D. , Bentley C. , Ludemann B. , Farooque Mohammad , Oei P. , Rauseo Anthony
Published: May 2008

FuelCell Energy, Inc. (FCE) manufactures a range of powerplant products based on the Direct FuelCellÒ (DFCÒ) technology. FCE has been producing commercial powerplant products since 2003, and the product line currently consists of powerplants ranging from 300kW to 2.4MW in output rating. The products produce electricity and heat from a variety of fuels, including natural gas as well as renewable fuels such as anaerobic digester gas from wastewater or food processing. The non-combustion, direct electrochemical conversion used in these products results in ultra-clean exhaust, the highest efficiency (and lowest CO2 generation) of power generation products in their size range. The installed fleet of commercial products is exhibiting availability in the mid 90's and product cost has been reducing significantly.
Electrochemical Formation of Ta and Ti Oxide Etch Masks from an Anodized Al Template for Formation of Quantum Semiconductor Wires
Authors: Arvin Charles L. , Miller Albert
Published: May 2008

The anodized aluminum oxide (AAO) template with tunable pore sizes from 4 to 400 nm has been proposed as a reverse image mask to produce Si wires. Instead of electrochemically forming the semiconducting material, a Si substrate was used as the base material and a RIE etch mask with the proper dimensions was produced through a two-stage anodization of a metal bi-layer (Ta/Al and Ti/Al). The anodization was monitored using chronoamperometry, and the resulting structures were characterized using FESEM images before and after RIE etching. The TaOx rods were an inverse image of the AAO template. However, the RIE parameters chosen collapsed the rods into teepee formations which transferred that pattern into the Si. On-going work is focused on reducing the thickness of underlying Ta, improving the quality of rods and changing to a two-step RIE process, in order to avoid this phenomenon.
Electrochemical Processing of Nanoscale Si Thin Film in a Hydrophobic Room-Temperature Molten Salt
Authors: Nishimura Yusaku , Fukunaka Yasuhiro , Nohira Toshiyuki , Hagiwara Rika
Published: May 2008

The electrodeposition of silicon has been studied in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl)imide containing 0.1 M SiCl4. Cyclic voltammetric studies suggest that SiCl4 should be reduced around −2.0 V. Potentiostatic electrolysis at −2.0 V forms a yellowish-brown film on a Ni substrate. The results of energy dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy reveal that the electrodeposited film contains amorphous silicon. Part of the electrodeposited film surface was oxidized in the air during transportation from the glove box to the analysis apparatuses. However, the Si electrodeposited in the present system is much more stable than that in propylene carbonate containing 0.5 M SiCl4 and 0.1 M tetrabutylammonium chloride. Furthermore, highly uniform and dense thin film is obtained in the initial stage of electrolysis in the present system.
CdS Films Dposited by the Pulse Plating Technique and Their Characteristics
Authors: Murali K. R. , Thilakavathy K , Ooman Rachel
Published: May 2008

CdS films were pulse at different duty cycles in the range 6 - 50 % using AR grade cadmium sulphate and sodium thiosulphate precursors. The as deposited films exhibited cubic structure. Optical band gap of the films increased with decrease of duty cycle. XPS, EDAX and AES studies confirmed the formation of CdS. Laser Raman studies indicated LO and TO phonons of CdS. Photoluminescence spectra of the films indicated broad bands at 2.30 eV and 1.80 eV corresponding to interband transitions and sulphur vacancies. Mott- Schottky studies indicated a flat band potential of -1.10V(SCE) and a carrier density of 2.0 x 1017 cm-3.
Pulse Plated Cadmium Telluride Films and Their Characteristics
Authors: Murali K. R. , Thirumoorthy P. , Sengodan V.
Published: May 2008

Cadmium Telluride thin films were deposited on conducting glass and titanium substrates by the pulse plating technique at different duty cycles in the range 10 - 50 %. The films were characterized by x-ray diffraction and they were found to possess single phase cubic structure. Optical studies indicated a direct band gap of 1.45 eV. Surface morphology of the films indicated that the crystallite size increases with increase of duty cycle. XPS studies confirmed the formation of CdTe. EDAX studies were made to estimate the composition. Cross plane resistivity measurements indicated that the resistivity decreases with increase of duty cycle.
Electrochemical Deposition of Copper Pentagonal Microcrystals
Authors: Ostapenko Gennady I. , Denisova Diana A. , Vikarchuk Anatoly A.
Published: May 2008

Potentiostatic growth of copper microcrystals is investigated on titanium nitride substrate. Electrodeposition occurs at overvoltages more than 30...35 mV. Progressive nucleation with three-dimensional growth under the diffusion control is observed at comparatively lower overvoltages. The trend of the deviation to the instantaneous nucleation occurs at increased overvoltages. Pentagonal copper microcrystals are preferentially formed at 40...60 mV overvoltages.
Sex differences in circulating and renal angiotensins of hypertensive mRen().Lewis but not normotensive Lewis rats
Authors: Pendergrass Karl D. , Pirro Nancy T. , Westwood Brian M. , Ferrario Carlos M. , Brosnihan K. Bridget , Chappell Mark C.
Published: May 2008

Sex differences in blood pressure are evident in experimental models and human subjects, yet the mechanisms underlying this disparity remain equivocal. The current study sought to define the extent of male-female differences in the circulating and tissue renin-angiotensin aldosterone systems (RAASs) of congenic mRen( 2 ).Lewis and control Lewis rats. Male congenics exhibited higher systolic blood pressure than females [200 ± 4 vs. 146 ± 7 mmHg, P < 0.01] or Lewis males and females [113 ± 2 vs. 112 ± 2 mmHg, P > 0.05]. Plasma ANG II levels were twofold higher in male congenics [47 ± 3 vs. 19 ± 3 pM, P < 0.01] and fivefold higher than in male or female Lewis rats [6 ± 1 vs. 6 ± 1 pM]. ANG I levels were also highest in the males; however, plasma ANG-(1-7) was higher in female congenics. Male congenics exhibited greater circulating renin and angiotensin-converting enzyme (ACE) activities, as well as angiotensinogen, than female littermates. Renal cortical and medullary ANG II levels were also higher in the male congenics versus all the other groups; ANG I was lower in the males. Cortical ACE2 activity was higher in male congenics, yet neprilysin activity and protein were greater in the females, which may contribute to reduced renal levels of ANG II. These data reveal that sex differences in both the circulating and renal RAAS are apparent primarily in the hypertensive group. The enhanced activity of the RAAS in male congenics may contribute to the higher pressure and tissue injury evident in the strain.
Paradoxical role of alveolar macrophage-derived granulocyte-macrophage colony-stimulating factor in pulmonary host defense post-bone marrow transplantation
Authors: Ballinger Megan N. , Hubbard Leah L. N. , McMillan Tracy R. , Toews Galen B. , Peters-Golden Marc , Paine Robert , Moore Bethany B.
Published: May 2008

Impaired host defense post-bone marrow transplant (BMT) is related to overproduction of prostaglandin E2(PGE2) by alveolar macrophages (AMs). We show AMs post-BMT overproduce granulocyte-macrophage colony-stimulating factor (GM-CSF), whereas GM-CSF in lung homogenates is impaired both at baseline and in response to infection post-BMT. Homeostatic regulation of GM-CSF may occur by hematopoietic/structural cell cross talk. To determine whether AM overproduction of GM-CSF influenced immunosuppression post-BMT, we compared mice that received BMT from wild-type donors (control BMT) or mice that received BMT from GM-CSF−/− donors (GM-CSF−/− BMT) with untransplanted mice. GM-CSF−/− BMT mice were less susceptible to pneumonia with Pseudomonas aeruginosa compared with control BMT mice and showed antibacterial responses equal to or better than untransplanted mice. GM-CSF−/− BMT AMs displayed normal phagocytosis and a trend toward enhanced bacterial killing. Surprisingly, AMs from GM-CSF−/− BMT mice overproduced PGE2, but expression of the inhibitory EP2receptor was diminished. As a consequence of decreased EP2receptor expression, we found diminished accumulation of cAMP in response to PGE2stimulation in GM-CSF−/− BMT AMs compared with control BMT AMs. In addition, GM-CSF−/− BMT AMs retained cysteinyl leukotriene production and normal TNF-α response compared with AMs from control BMT mice. GM-CSF−/− BMT neutrophils also showed improved bacterial killing. Although genetic ablation of GM-CSF in hematopoietic cells post-BMT improved host defense, transplantation of wild-type bone marrow into GM-CSF−/− recipients demonstrated that parenchymal cell-derived GM-CSF is necessary for effective innate immune responses post-BMT. These results highlight the complex regulation of GM-CSF and innate immunity post-BMT.
Transforming growth factor-β1 protects against pulmonary artery endothelial cell apoptosis via ALK5
Authors: Lu Qing
Published: May 2008

Transforming growth factor (TGF)-β1 has been reported to cause endothelial cell apoptosis. However, conflicting data have also demonstrated that TGF-β1 promotes endothelial cell survival. In this study, the effect of TGF-β1 on apoptosis of cultured bovine pulmonary artery endothelial cells (PAEC) induced by multiple stimuli was investigated. TGF-β1 protected against apoptosis of bovine PAEC induced by serum deprivation or the VEGF receptor inhibitor SU-5416, but not by UV light exposure or TNFα. Neither caspase-8 nor caspase-12 was activated by serum deprivation or the VEGF receptor blocker. However, blockade of VEGF receptors activated caspase-9, an effect that was abolished by TGF-β1. Furthermore, serum deprivation and inhibition of VEGF receptors significantly decreased the protein level of Bcl-2, an effect that was also abrogated by TGF-β1. In addition, the baseline level of Bcl-2 was enhanced by TGF-β1 and reduced by inhibition of activin receptor-like kinase 5 (ALK5), a TGF-β1 type I receptor. Furthermore, inhibition of ALK5 caused apoptosis of bovine PAEC. These results suggest that TGF-β1 signaling is critical for maintenance of bovine PAEC survival. Finally, the protective effects of TGF-β1 on bovine PAEC apoptosis and Bcl-2 reduction were abolished by ALK5 inhibition, but not by inhibition of non-SMAD signaling pathways. Also, TGF-β1 activated SMAD2 and SMAD1/5, an effect that was abolished by ALK5 inhibition. The results of this study suggest that TGF-β1 protects against bovine PAEC apoptosis, possibly through ALK5-mediated Bcl-2 induction and subsequent inhibition of the mitochondria-mediated intrinsic pathway of apoptosis. Understanding the mechanism by which TGF-β1 promotes endothelial cell survival may provide a better treatment for apoptosis-dependent vascular diseases, such as emphysema.
Contralateral muscle activity and fatigue in the human first dorsal interosseous muscle
Authors: Post Marijn , Bayrak Sibel , Kernell Daniel , Zijdewind Inge
Published: May 2008

During effortful unilateral contractions, muscle activation is not limited to the target muscles but activity is also observed in contralateral muscles. The amount of this associated activity is depressed in a fatigued muscle, even after correction for fatigue-related changes in maximal force. In the present experiments, we aimed to compare fatigue-related changes in associated activity vs. parameters that are used as markers for changes in central nervous system (CNS) excitability. Subjects performed brief maximal voluntary contractions (MVCs) with the index finger in abduction direction before and after fatiguing protocols. We followed changes in MVCs, associated activity, motor-evoked potentials (MEP; transcranial magnetic stimulation), maximal compound muscle potentials (M waves), and superimposed twitches (double pulse) for 20 min after the fatiguing protocols. During the fatiguing protocols, associated activity increased in contralateral muscles, whereas afterwards the associated force was reduced in the fatigued muscle. This force reduction was significantly larger than the decline in MVC. However, associated activity (force and electromyography) remained depressed for only 5–10 min, whereas the MVCs stayed depressed for over 20 min. These decreases were accompanied by a reduction in MEP, MVC electromyography activity, and voluntary activation in the fatigued muscle. According to these latter markers, the decrease in CNS motor excitability lasted much longer than the depression in associated activity. Differential effects of fatigue on (associated) submaximal vs. maximal contractions might contribute to these differences in postfatigue behavior. However, we cannot exclude differences in processes that are specific to either voluntary or to associated contractions.
Adiponectin Decreases C-Reactive Protein Synthesis and Secretion From Endothelial Cells
Authors: Devaraj Sridevi , Torok Natalie , Dasu Mohan R. , Samols David , Jialal Ishwarlal
Published: May 2008

Background and Objective—

Inflammation is pivotal in atherosclerosis. C-reactive protein (CRP), in addition to being a cardiovascular risk marker, may also be proatherogenic. We have previously shown that in addition to the liver, human aortic endothelial cells (HAECs) synthesize and secrete CRP. Whereas CRP levels are increased in obesity, metabolic syndrome, and diabetes, levels of adiponectin are reduced in these conditions. We tested the hypothesis that adiponectin reduces CRP synthesis and secretion in HAECs under normoglycemic (5.5 mmol/L glucose) and hyperglycemic conditions (15 mmol/L glucose).

Methods and Results—

Adiponectin dose-dependently reduced CRP mRNA and protein from HAECs. Adiponectin treatment of HAECs significantly decreased IκB phosphorylation and NFκB binding activity. There was no effect of adiponectin on STAT or C/EBP transcriptional activity. Adiponectin also activated AMP kinase resulting in decreased NFκB activity and decreased CRP mRNA and protein. These effects of adiponectin were mimicked by AICAR, an activator of AMPK, and reversed by inhibition of AMPK. Thus, adiponectin reduces CRP synthesis and secretion from HAECs under hyperglycemia via upregulation of AMP kinase and downregulation of NFκB. Similar findings were observed in rat primary hepatocytes.

Conclusions—

Thus, in obesity and diabetes, the hypoadiponectinemia could exacerbate the proinflammatory state by inducing CRP production.