bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct Internal Steam Reforming at SOFC with Anode Prepared Using NiO-SDC Composite Particles
Authors: Kawano Mitsunobu , Matsui Toshiaki , Kikuchi Ryuji , Yoshida Hiroyuki , Inagaki Toru , Eguchi Koichi
Published: May 2007

The dependence of anode catalytic activities on the fuel species and the operating temperatures was investigated for use in the direct internal steam-reformed power generation. The SOFCs employing Ni-SDC cermet anode fabricated from the NiO-SDC composite particles were operated in the temperature range of 700-1000{degree sign}C by feeding the humidified hydrogen and methane as fuels. The cell performances with humidified hydrogen fuel were higher than those with humidified methane fuel at every operation temperature. The performances at 700 and 800{degree sign}C were much lower than that at 1000{degree sign}C when the humidified methane fuel was supplied. Considering the results of the electrochemical characterization and the microstructural observation of anode, the methane conversion and the deposited carbon appeared to significantly affect the cell performances.
On the Redox Cycling of Anode-Supported SOFCs: Mechanical Properties and Damage Mechanisms
Authors: Sarantaridis Dimitris , Rudkin Robert A. , Atkinson Alan
Published: May 2007

Investigations on SOFCs using Ni-based anode supports are presented aiming at the understanding of how much oxidation such a cell can tolerate before incurring irreversible mechanical damage. The dimensional strains, elastic modulus and porosity of typical anode supports were measured as a function of the degree of oxidation. The mechanical stability of cells incorporating such substrates was studied as a result of oxidation by air and by electrochemical oxidation. The different oxidation procedures performed showed different damage modes. In free-standing cells the main damage mode was electrolyte cracking, but in cell test configurations the cells failed by substrate cracking. This was mainly due to the non-uniform nature of anode oxidation in the cell test configurations which can lead to cell failure when the degree of oxidation is only 5 %. The observations are interpreted using models of the stress generation and fracture processes.
Dimensional Behaviour of Ni-YSZ Anode Supports for SOFC Under RedOx Cycling Conditions
Authors: Pihlatie Mikko , Kaiser Andreas , Larsen Peter H. , Mogensen Mogens
Published: May 2007

Previous studies on Ni-YSZ anode supported SOFC have shown severe mechanical failures upon re-oxidation of the nickel. Ni- YSZ anode support cermets with technologically relevant microstructures were prepared by ceramic slurry processing, tape casting and sintering. The bulk behaviour of the anode supports under reduction-oxidation cycles was studied in dilatometry in temperature range 850 to 1200 deg C. The expansion on the 1st re-oxidation was measured at 0.68 to 0.93%, depending on temperature, and on subsequent redox cycles the high temperature case became strongly irreversible. In tests where humidity was introduced and the pO2 was varied, the effect of steam on redox expansion behaviour was found to be detrimental. Parameters describing the reversibility of cyclic redox behaviour are defined and compared in different cases. The processes leading to the observed irreversibility are discussed.
Experimental and Modeling Study of the Impedance of Ni/YSZ Cermet Anodes
Authors: Gewies Stefan , Bessler Wolfgang G. , Sonn Volker , Ivers-Tiffee Ellen
Published: May 2007

We present a combined experimental and modeling study of the impedance of Ni/YSZ cermet anodes. Experiments are performed using symmetrical cells with 30 µm electrodes and 195 µm YSZ electrolyte. Impedance spectra are recorded in H2/H2O/N2/He atmospheres over a wide range of operating conditions (650-900{degree sign}C, 4-46% H2O). The data are analyzed by both, an equivalent circuit model consisting of 4 RQ elements, and a two-dimensional detailed-chemistry kinetic model. The combined results allow a detailed insight into the coupled electrochemical and transport processes. This enables identification of the physical origin of the impedance features: 1) charge-transfer (hydrogen spillover reaction) and electrical double layer; 2) gas diffusion in the supply channels; 3) gas diffusion in the current collector mesh.
Nano-metal Dispersed Anode of Intermediate-temperature SOFC for High Power Density Operation
Authors: Awatsu Satoshi , Iwasaki Hitomi , Isono Keiko , Chitose Norihisa , Uozumi Gakuji , Inagaki Toru , Ishihara Tatsumi
Published: May 2007

Improvements of the anode and the fuel side current collector has been carried out in order to increase the output power of the intermediate-temperature (IT) solid oxide fuel cells (SOFCs) using lanthanum gallate electrolyte. Dispersion of nano-size metal in the cermet anode composed of Sm doped ceria (SDC) and Ni has been tried. As a source material to manufacture the novel anode, SDC powder incorporated with nano-size Ru particles was developed. In order to achieve in-situ production of hydrogen inside the cell-stack, fuel side current collectors were impregnated with catalyst metals such as Ru or Ni. It was demonstrated experimentally that the developed current collectors have high catalytic activity for steam reforming reaction of methane and also have favorable effect to increase the power density. Replacement of the dopant to ceria from Sm to Gd is also tested both for the anode and the fuel side current collector.
Stability of Nickel-based Cermet Anode for Carbon Deposition during Cell Operation with Slightly Humidified Gaseous Hydrocarbon Fuels
Authors: Yamaji Katsuhiko , Kishimoto Haruo , Yueping Xiong , Horita Teruhisa , Sakai Natsuko , Brito Manuel E. , Yokokawa Harumi
Published: May 2007

Stability of nickel-based cermet anode for carbon deposition had been investigated with little humidified gaseous hydrocarbon fuels (methane, ethane, and propane) as functions of operation temperature and fuel utilization rate. High operation temperature and/or low fuel utilization rate caused severe carbon deposition on the anode in the vicinity of the fuel injection port. The amount of deposited carbon decreased with decreasing the operation temperature and/or increasing the fuel utilization rate. Ni-ScSZ anode-supported cells had been stably operated without severe carbon deposition for 80 to 150 hours; for methane at T = 973 K and Uf = 50 %, for ethane at 823 K and Uf = 50 %, for propane at 773 K Uf = 75 %, respectively.
Direct Feeding of Liquid Fuel in SOFC
Authors: Kishimoto Haruo , Xiong Yue-Ping , Yamaji Katsuhiko , Horita Teruhisa , Sakai Natsuko , Brito Manuel E. , Yokokawa Harumi
Published: May 2007

Direct feeding of n-dodecane (C12H26, a model fuel of kerosene) was carried out using a solid oxide fuel cell consisting of scandia stabilized zirconia (ScSZ) electrolyte and Ni-ScSZ cermet anode. Influence of operating conditions such as temperature and fuel dilution was investigated on the cell performance, on the carbon deposition, and on the anode degradation. When fuel was fed to the anode without dilution, a stable operation was achieved under the conditions of about 160 mA/cm2 (about 65 % fuel utilization) and anode potential of - 0.75 V for about 50 h. No carbon deposition was observed on the Ni-ScSZ anode after the operation. Compared with cases with diluted fuels, carbon deposition on the outlet gas tube was suppressed in the non-diluted condition of n-dodecane, while the output power was nearly the same.
A New Approach for Elementary-Kinetic Modeling of Internal-Reforming SOFCs
Authors: Bessler Wolfgang G. , Gewies Stefan , Vogler Marcel
Published: May 2007

Current SOFC cell-level models are based on the subtraction of electrode overpotentials from an equilibrium potential calculated using the Nernst equation. This approach can only be applied to situations where the equilibrium potential is defined. It fails for non-equilibrium gas feeds as occurring in internal-reforming mode (e.g. CH4/H2O mixtures). We present here a new modeling approach that does not use the Nernst equation. It is based on the combination of a physical representation of electrical potential steps and an elementary-kinetic description of electrochemistry, where multi-step chemical mechanisms account for coupled and spatially distributed charge-transfer and reforming chemistry. The model is applied to an internal-reforming SOFC operated on CH4/H2O mixtures. The simulations allow to predict the open-circuit voltage which is considerably below the value resulting from full equilibration and furthermore strongly depends on anode thickness. Concentration variations within the porous anode lead to electrochemical activity even at open circuit.
Dynamic Simulation Tool APROS in SOFC Power Plant Modeling at Wärtsilä and VTT
Authors: Ollikainen Toni , Saarinen Jaakko , Halinen Matias , Hottinen Tero , Noponen Matti , Fontell Erkko , Kiviaho Jari
Published: May 2007

Wärtsilä Corporation is developing SOFC systems for the power ranges of 200 kW and above. Currently the work is focused on a 5 kW test system and a 20 kW prototype unit. Reliable system development requires dynamic simulation, and APROS (Advanced Process Simulation Software) has been chosen as the tool for this work. Development work has been made for modeling fuel cell power plant by preparing modules for SOFC stacks, sulfur removal units, natural gas reformers, catalytic afterburners, and power conditioning systems. The implementation of a zero and one-dimensional SOFC stack model into APROS has been made and the results are under validation. In this contribution, the functionality of modeling these test systems has been studied at the component and system levels. Measurement data is available from both Wärtsilä Corporation and VTT from their own 5 kW test systems that have been running for over 4000 hours.
Three Dimensional Reconstruction of Solid Oxide Fuel Cell Electrodes Using Focused Ion Beam - Scanning Electron Microscopy
Authors: Wilson James , Kobsiriphat Worawarit , Mendoza Roberto , Chen Hsun-Yi , Hines Tom , Hiller Jon , Miller Dean , Thornton Katsuyo , Voorhees Peter , Adler S.B. , Mumm Daniel R. , Barnett Scott
Published: May 2007

Solid oxide fuel cell (SOFC) electrodes typically consist of contiguous electronically and ionically conducting solid phases in an interconnected porous structure. Quantitatively analyzing this microstructure remains a key challenge in connecting materials processing with electrode performance. This paper will describe the application of dual-beam focused ion beam - scanning electron microscopy for three-dimensional reconstruction of Ni-YSZ cermet anodes, LSM-YSZ cathodes, and (La,Sr)CoO3 cathodes. Different methods for segmentation, i.e. converting images to 3D data sets, are compared and the tradeoff between calculation accuracy and analysis time is discussed.
Analysis of Performance Characteristics of Intermediate-Temperature Disk Type SOFC Using Pure Hydrogen
Authors: Tanaka Tadashi , Kanno Tomoyoshi , Nakamura Takuya , Inui Yoshitaka , Chitose Norihisa , Miyazawa Takashi , Akbay Taner
Published: May 2007

In this study, a one-dimensional simulation code of intermediate-temperature disk type SOFC is developed. The single cell voltage-current density characteristic curves and the temperature dependence of the single cell voltage are calculated. The numerically estimated single cell voltage is about 0.02 V higher than that of the experimental result when the electronic conductivity of the electrolyte is not taken into consideration. To address this discrepancy, the electronic resistivity is incorporated in the simulation code. The numerically obtained single cell voltage coincides well with the experimental one in this case. The dependence of the single cell voltage on the cell temperature is also investigated. It is made clear that the single cell voltage takes the highest value when the cell temperature is about 760C for nominal current density.
Numerical Modelling of Radiative Heat Transfer in an SOFC System
Authors: Brus Grzegorz , Szmyd Janusz
Published: May 2007

The present paper describes numerical modelling of the radiative heat transfer process in the module chamber of an Internal Indirect Reforming-type SOFC. The ability to do internal reforming is one of the characteristics of high temperature fuel cells, SOFC. As in any high-temperature system, radiative heat transfer is important. In this article, heat transfer between the fuel reformer surface and all other surfaces facing to the reformer surfaces is modelled. Governing equations for radiative heat transfer are described using Hottel's zone method. The resulting radiation-conduction conjugate heat transfer problems are numerically solved with a combination of Gauss-Seidel and Newton-Raphson methods. The obtained results indicate that, for the development of effective indirect internal reforming, the position of the reformer in the module chamber and emissivity of the surfaces of the reformer, cell and other elements in the SOFC module all play a key role.
Reversible SOFC Model as a Base of Design and Testing
Authors: Winkler Wolfgang
Published: May 2007

The utilisation of the fuel changes the gas concentrations in the gas channels of fuel cells depending on the ionic transport mechanism. A reversible model is used to describe the influence of fuel utilisation, thermodynamic state, and operational parameters on the local Nernst voltage. It defines the borders and the framework of any modelling of oxygen conducting cells (SOFC) and proton conducting cells, because reversible processes are the limiting processes of any real processes. The integration of the solutions for a fuel utilisation from 0 to 1 delivers the free enthalpy of the reaction plus the reversible work of mixing in the gas channels as a result and shows a global validity of this modelling approach. These basic influences will be identified, compared, and discussed regarding its practical use for modelling and testing of real cells for hydrogen and hydrocarbons as a fuel.
Micro-structural Modelling of SOFC Anodes
Authors: Golbert Joshua , Adjiman Claire , Brandon Nigel P.
Published: May 2007

Attempts to improve fuel cell performance have lead to the development of porous structure composite electrodes, which increase the amount of triple phase boundaries (TPB), where the electrochemical reactions actually occur. The interplay between the number of TPBs, the conductivity/diffusivity of the electrode, and the performance depends on the microstructure and operating conditions. Attempts to develop models for electrodes commonly assume effective values for key parameters. However, such models lack accuracy and insight into the conditions at the TPB. A framework modeling electrodes as amorphous agglomerates of particles of various sizes is presented. The basic properties of the underlying microstructure are analyzed, providing insight on the design of electrodes in a first-principles fashion as opposed to trial and error. In addition, this framework lays the foundation for multiscale modeling both in smaller scale at the reaction sites and in terms of the large scale cell and stack level.
Fabrication of Ce1-xGdxO2-0.5x Electrolytes with Tunable Dense Microstructures for IT-SOFC Applications
Authors: Esposito Vincenzo , Fonseca Fabio Coral C. , De Florio Daniel Z. , Zunic Milan , Muccillo Reginaldo , Traversa Enrico
Published: May 2007

Nano-sized Ce1-xGdxO2-0.5x (0 < x < 0.3) powders, with a narrow particle size distribution in the 5-10 nm range, were synthesized via a soft chemical route. The obtained materials showed to be highly sinteractive and their grain growth to be strongly controlled by gadolinium dopant content. Selected fast firing and conventional sintering processes were used to tailor the dense microstructures of the electrolytes. The combined effects of grain size and dopant content on the electrical properties was evaluated taking into consideration the bulk and the grain boundary of the final microstructures. A careful control of the sintering parameters showed to be crucial for the fabrication of tunable microstructures of nano- electroceramics for IT-SOFC components.
Ionic Conductivity in Lanthanoid Ion-doped BaCeO3 Electrolytes
Authors: Kikuchi Jun , Koga Seiji , Kishi Katuyuka , Saito Morihiro , Kuwano Jun
Published: May 2007

Oxide ion conductivity was examined in BaxCe0.8Ln0.2O3-δ (0.8{less than or equal to}x{less than or equal to}1.1; Ln=Lanthanoid). The slightly Ba-deficient compositions showed a higher conductivity than the nominal stoichiometric ones. A maximum total (bulk) conductivity (σ=5.5×10-4 Scm-1 at 250ºC, σ=9.6×10-3 Scm-1 at 500oC) was found in the Ba-deficient composition Ba0.975Ce0.8Gd0.2O3-δ. The σ value at 250oC was nearly two times higher than that of the known BaCe0.8Gd0.2O3-δ electrolyte. The conductivity is the best of those of known oxide ion conductors at intermediate temperatures. The non-stoichiometric Ba0.975Ce0.8Gd0.2O3-δ sample was a single phase of the monoclinic perovskite-related phase (I2/m). The high conductivity is attributed to the fact that the Gd-doped composition had the largest cell volume in the Ln-doped series. The unusual variation of the cell volume was due to a change in the portioning of the Ln ion between the B-site and the A(Ba)-site.
SrZr1-xYxO3 Coatings Elaborated by DC Magnetron Sputtering
Authors: Pour Yazdi Mohammad Arab , Briois Pascal , Lapostolle Frédéric , Billard Alain
Published: May 2007

Solid electrolytes are of increasing importance for various applications such as fuel cells, sensors or electro-catalysts. In particular, the current tendency for high temperature fuel cells is to decrease the operating temperature around 773-973K. Among the different solution involved to reach this goal, a new class of fuel cell is proposed in the literature: proton conductor fuel cells (PCFC) based on protonic conductor electrolytes which present a higher ionic conductivity than anionic conductor electrolytes. Among the different materials possible for PCFC: SrZr1-xYxO3 crystallised under perovskite structure present an interesting compromise between protonic conductivity and chemical stability. In this paper, we then investigate the feasibility of such coatings by co-sputtering on a rotating substrate-holder of metallic Sr and Zr0.84Y0.16 targets in the presence of reactive argon-oxygen gas mixtures. We have studied the evolution of composition of the coatings as a function of the discharge current dissipated on each target. The coating, initially amorphous, crystallised in the convenient pervoskite structure after annealing treatment under air at 673 K for 2 hours. Finally, SEM observations were realised to verify that the coatings morphology is compatible with their application as PCFC electrolyte.
Performance of BaZrO3 based Proton Conductors as an Electrolyte for Intermediate Temperature Operating SOFC
Authors: Iguchi Fumitada , Tokikawa Takuro , Miyoshi Takanori , Tsurui Takao , Nagao Yuki , Sata Noriko , Yugami Hiroo
Published: May 2007

Investigative results of Y concentration dependence of total conductivity, and testing results of self-supported cells, gave us knowledge to realize intermediate temperature operating SOFCs using Y-doped BaZrO3 proton conductors. An increase of Y concentration improved electrical properties of grain boundaries drastically. As a result, total conductivity of a 15mol% Y doped BaZrO3 sample in wet air and wet Ar showed 5mScm-1 at 400oC. The performance of the self-supported cells was very low because of high electrolyte resistance caused by those thicknesses. Open circuit voltage (OCV) was over 1V in the temperature range of 600oC to 400oC in spite of low ionic transparent number in wet air at 600oC. Degradation of electrolytes was not observed during tests. From those results, electrode-supported cells using Y-doped BaZrO3 will show sufficient cell performance for intermediate temperature SOFCs.
The somatic female gonad of Cephalobidae (Nematoda): cellular architecture and associated function
Authors: Bert Wim , Vangestel Sandra , Houthoofd Wouter , Van Gansbeke Ruben , Borgonie Gaëtan
Published: May 2007

The female reproductive system of the free-living nematode family
Cephalobidae is examined by means of differential interference contrast,
scanning electron and fluorescent microscopy. The model nematode
Caenorhabditis elegans and the predatory nematode Prionchulus punctatus are
also included in this study; the former mainly to test our results with the
very detailed knowledge of this model organism, the latter to provide a
representative of the more distantly related Enoplea. In this comparative
approach, the analysed gonad structures are discussed with respect to their
functional and phylogenetic significance. The general cellular composition
of the cephalobid gonad – namely an oviduct comprising two rows of four
cells, a distinctly offset spermatheca consisting of 8-16 cells, and a
uterus composed of distinct cell rows – differs from all known Nematoda
except that of the plant-parasitic Tylenchomorpha. Despite the striking
evolutionary conservation of the cellular architecture of the cephalobid
gonad there is a complex subcellular specialisation, namely a significant
and functionally relevant variation in myofilament organisation, both among
Cephalobidae and between major groups of nematodes. We demonstrate the
presence of microfilaments that vary in pattern among species and that may
play an important role in egg propulsion. The phenomenon of endotokia
matricida, in which eggs do not leave the female body, is found to be
associated with a massive rupture of the cytoskeleton in the uterus wall.
The complexity of the myofibril structure and the associated potential to
propagate oocytes actively cannot be solely explained by differences in
phylogenetic history, but is also linked to body diameter. In the larger
Acrobeloides maximus, the proximal end of the ovary sheath is adorned with
12 distinct longitudinal bands, antibody binding positively for paramyosin,
while in the smaller Cephalobus cubaensis myofilament organisation is at
random.
A key and diagnostic compendium to the species of the genus Merlinius Siddiqi, 1970 (Nematoda: Tylenchida) with description of Merlinius khuzdarensis n. sp. associated with date palm
Authors: Handoo Zafar , Khan Aly , Islam Shamsul
Published: May 2007

An identification key to 32 valid species of stunt nematodes (Merlinius spp.)
is given. A compendium of the most important diagnostic characters for use
in identification of species is included as a practical alternative and
supplement to the key. The diagnosis of Merlinius is emended and a list of
all valid species of the genus is given. The characters most useful for
separating species include body and stylet lengths, shape of head, tail and
tail terminus, number of head and tail annules, position of vulva (V), and
c′ ratio in females. Also useful are length and shape of spicules and
gubernacula in males. A new stunt nematode, Merlinius khuzdarensis n. sp.,
from the rhizosphere of date palm (Phoenix dactylifera L.) from Khuzdar,
Balochistan Province, Pakistan, is described and illustrated. This new
species resembles M. bavaricus, M. communicus, M. bilqeesae and M. montanus,
but differs from these species by the following: body and stylet length,
shape of head, tail and tail terminus, number of head and tail annules, and
position of phasmids. Because this species is limited in distribution, its
economic importance in date palm and other cultivated crops within the
region is not known.
Do phytohormones influence nematode invasion and feeding site establishment?
Authors: Curtis Rosane
Published: May 2007

Phytohormones mediate important aspects of developmental processes in plants and may participate in various aspects of plant nematode interactions. Several reports demonstrate that nematode infection interferes with plant auxin flow and accumulation, and that auxin is necessary for feeding site formation. Other plant hormones, such as ethylene, might be modulating several cellular processes during feeding site formation. So far, the nematode molecules involved in activating these processes in planta have not been identified. Auxin can act as a signalling molecule by inducing changes in the surface cuticle and behaviour of Meloidogyne spp. and these changes might be essential for infection. Auxin binds to the chemosensory organs, amphids and phasmids and also to several tail neurons of Meloidogyne spp. This interaction might allow these nematodes to sense and follow an auxin gradient through amphidial or phasmidial receptors during penetration and migration inside roots.
Two new species of Schistonchus (Nematoda: Aphelenchoididae) associated with Ficus hispida in China
Authors: Zeng Yongsan , Giblin-Davis Robin M. , Ye Weimin
Published: May 2007

Two new nematode species of the genus Schistonchus were recovered from
syconia from a single Ficus hispida caprifig tree in Guangzhou, China. They
are described herein as Schistonchus guangzhouensis n. sp. and S. centerae
n. sp. Schistonchus guangzhouensis n. sp. is characterised by possessing the
longest postuterine sac (PUS) of all currently described females in the
genus (84-148 μm or >3.5 vulval body diam. (VBD) long), excretory pore
situated near the level of the metacorpus, two pairs of subventral papillae
on the male tail, and unique recurved and mitten-shaped spicules.
Schistonchus centerae n. sp. is characterised by a unique fusiform tail tip
and short PUS (8-20 μm or <1.0 VBD long) in reproductive females,
excretory pore located near the head, spicules with an indistinct rostrum,
male tail with three pairs of papillae, and broadly truncate tail tip. Both
new species were easily differentiated from each other and other members of
the genus for which sequences of the D2/D3 expansion segments of the large
subunit rRNA gene (LSU) and partial small subunit rRNA gene (SSU) were
available. Phylogenetic analysis also supported a monophyletic Schistonchus
within a well-supported clade of Aphelenchoididae (sensu Hunt, 1993) and
shared a most recent common ancestor with Aphelenchoides and
Laimaphelenchus.
Eddy Advective and Diffusive Transports of Heat and Salt in the Southern Ocean
Authors: Lee Mei-Man , Nurser A. J. George , Coward A. C. , de Cuevas B. A.
Published: May 2007

There are two distinct mechanisms by which eddies provide systematic transport of tracer on isopycnals: the advective transport, associated with the slumping of isopycnals, and the diffusive transport, associated with down-gradient diffusion. Depending on the large-scale tracer distribution, eddy advective transport has either the same direction as or opposite direction to eddy diffusive transport. As a consequence, eddy advection and eddy diffusion can reinforce each other for some tracers but oppose each other for other tracers. Using scaling analysis, it is argued that the relative directions of eddy advective and diffusive transports can be determined simply from the relative slopes of tracers and isopycnals. An eddy-resolving (1/12°) global ocean model is used to illustrate the two eddy transport mechanisms for temperature and salinity in the Southern Ocean. Applications to other tracers, such as oxygen, are discussed. The diagnosed eddy diffusivity for temperature (and salinity) is found to be considerably different from the eddy diffusivity for eddy advective transport velocity.
Kill a Leader, Murder a Movement? Leadership and Assassination in Social Movements
Authors: Bob Clifford , Nepstad Sharon Erickson
Published: May 2007

All too frequently, governments kill social movement leaders in an attempt to halt challenges to state power. Sometimes such repression yields its intended effect; other times it produces a powerful backlash, strengthening mass commitment and bolstering protest. In this article, the authors propose hypotheses accounting for these divergent outcomes. Comparing El Salvador's liberation movement with Nigeria's Ogoni autonomy movement, they hypothesize that in addition to a movement's political opportunity structure, four factors internal to the movement matter: the type of leader, the movement's ideology of martyrdom, the leader's embodiment of a shared group identity, and the movement's preexisting unity.
Platform Leadership
Authors: Kretschmer Kelsy , Meyer David S.
Published: May 2007

The authors identify and describe a distinct type of social movement leadership, oriented toward promotion of a distinct position or set of arguments rather than toward any kind of grassroots mobilization. Platform leaders mold their organizations into vehicles that facilitate their interaction with mass media and mainstream political institutions. These leaders serve as the sole voice for their organizations in making public claims and exercise exclusive control over the organization's structure and profile. The authors use two case studies of movement organizations, Catholics for a Free Choice and Feminists for Life, to outline this style of leadership. They conclude with questions about the nature of social movement politics defined in this way.
Modelling Multi-layer Seam Puckering
Authors: Jin Lian Hu  , Ma Liang , George Baciu , Wong Wingo Sai-Keung , Zhang Weiyuan
Published: May 2007

This paper presents a method for modelling the seam puckering of multi-layer fabrics by considering the thread shrinkage as well as seam structure and fabric compression properties. A theoretical investigation and numerical calculation of forces acting on the sewing thread were carried out. Based on this, the forces causing the thread tension puckering were analyzed and a seam model to calculate the deformation of a multi-layer seam when threads shrink is presented. Three types of seams were simulated and satisfactory results were obtained
Image Quality of InkJet Printing on Polyester Fabrics
Authors: Park Heungsup , Carr Wallace W. , Ok Hyunyoung , Park Soomin
Published: May 2007

This paper is concerned with the image quality of lines that were inkjet printed on polyester woven fabric. Lines (ideal width of 0.1 mm) running in the warp and filling directions were inkjet printed on different fabrics, and print quality (line width, edge blurriness and edge raggedness) was assessed. The effects of fabric structural parameters (including fabric, yarn and fiber parameters), finishing (type and pick-up), and ink type on line image quality are discussed. Image quality depended on fabric construction, particularly for unfinished fabrics. The satin fabric had the worst image quality while the image quality on the plain fabric was best. Finishing can improve image quality; however, the type of finish was very important. Acrylic resin finish improved printing quality significantly, but results with polyurethane resin-finished fabric were not much better than for unfinished fabric. A volatile ink reduced wicking and improves line image quality; thus, image quality using the alcohol base ink was better than for the oil or glycol based inks.
Subependymal Periventricular Heterotopias in a Patient With Ehlers-Danlos Syndrome: A New Case
Authors: Savasta Salvatore , Crispino Mario , Valli Maurizia , Calligaro Alberto , Zambelloni Cesare , Poggiani Carlo
Published: May 2007

Ehlers-Danlos syndrome is a complex hereditary connective tissue disorder that is characterized by abnormalities of the skin and joints and visceral and neurological manifestations. At present, at least 11 forms are recognized on the basis of their clinical characteristics, methods of transmission, and biochemical defect. The neurologic manifestations include cerebrovascular disease, peripheral neuropathy, plexopathy, periventricular subependymal heterotopias, and epilepsy. Previously, 2 females were reported to be affected with subependimal periventricular heterotopias and Ehlers-Danlos syndrome type 1. The authors report a new case of a 12-year-old girl with similar clinical and neuroradiological features.
Acute Disseminated Encephalomyelitis Following Infectious Mononucleosis
Authors: Bahadori Hamid R. , Williams Virginia C. , Turner Robert P. , Rumboldt Zoran , Reigart J. Routt , Fowler Sandra L. , Chavis Pamela S. , Maria Bernard L.
Published: May 2007

Two months following an Epstein-Barr virus infection, a 17-year-old white female presented with seizures, intermittent visual changes, and altered mental status. Magnetic resonance imaging showed white matter changes of acute disseminated encephalomyelitis with a predilection for posterior cerebral artery distributions but without radiological evidence of arteritis. Epstein-Barr virus titers and polymerase chain reaction analysis results for the virus were consistent with postinfectious acute disseminated encephalomyelitis. The symptoms and signs improved following treatment with high-dose corticosteroids and intravenous immunoglobulin. Although Epstein-Barr virus can cause acute viral encephalomyelitis, the authors report a case of acute disseminated encephalomyelitis months after acute Epstein-Barr virus infection.
Gene expression variation in Down's syndrome mice allows prioritization of candidate genes
Authors: Sultan Marc , Piccini Ilaria , Balzereit Daniela , Herwig Ralf , Saran Nidhi G , Lehrach Hans , Reeves Roger H , Yaspo Marie-Laure
Published: May 2007

Background

Down's syndrome (DS), or trisomy 21, is a complex developmental disorder that exhibits many clinical signs that vary in occurrence and severity among patients. The molecular mechanisms responsible for DS have thus far remained elusive. We argue here that normal variation in gene expression in the population contributes to the heterogeneous clinical picture of DS, and we estimated the amplitude of this variation in 50 mouse orthologs of chromosome 21 genes in brain regions of Ts65Dn (a mouse model of DS). We analyzed the RNAs of eight Ts65Dn and eight euploid mice by real-time polymerase chain reaction.

Results

In pooled RNAs, we confirmed that trisomic/euploid gene expression ratios were close to 1.5. However, we observed that inter-individual gene expression levels spanned a broad range of values. We identified three categories of genes: genes with expression levels consistently higher in Ts65Dn than in euploids (9, 17, and 7 genes in cerebellum, cortex, and midbrain, respectively); genes whose expression levels partially overlap between the two groups (10, 9, and 14 genes); and genes with intermingled expression, which cannot be used to differentiate trisomics from euploids (12, 5 and 9 genes). Of the genes in the first category, App, Cbr1, and Mrps6 exhibited tight regulation in the three tissues and are therefore attractive candidates for further research.

Conclusion

This is the first analysis addressing inter-individual gene expression levels as a function of trisomy. We propose a strategy allowing discrimination between candidates for the constant features of DS and those genes that may contribute to the partially penetrant signs of DS.
Modelling of evaporation heat transfer of pure refrigerants and refrigerant mixtures in microfin tubes
Authors: Chamra L M , Mago P J
Published: May 2007

A semi-empirical model to predict the evaporation heat transfer of pure refrigerants and refrigerant mixtures flowing inside microfin tubes has been presented. The heat transfer coefficient correlation developed in the new model takes into account the nucleate boiling component and the forced convention component. The model was validated using a set of around 380 experimental data points compiled from published literature. Comparison shows that the model is capable of predicting evaporation heat transfer coefficients for different refrigerants and refrigerant mixtures within 10-25 per cent mean absolute deviation for the data sets.
The simian-type M and the human-type ABO blood groups in the African green monkey (Cercopithecus aethiops): their inheritance, distribution and significance for the management of a breeding colony
Authors: Terao K. , Hiyaoka A. , Cho F. , Honjo S.
Published: May 2007

We have established a new simian-type blood group system (M blood groups) in the African green monkey ( Cercopithecus aethiops), using a haemagglutinating antibody which was developed by alloimmunization. The M blood groups consisted of two phenotypes, type-M and type-m. We have also determined the mode of inheritance as well as the distribution of both simian-type M and human-type ABO blood groups, employing 113 families including 160 animals. The family analysis revealed that (1) the simian-type M blood groups were governed by the two alleles, dominant M and recessive m, and (2) the humantype ABO blood groups were governed by 3 alleles, codominant A and B and silent O, although no monkey of phenotype-O was found in our breeding colony. Differences in the phenotypic distribution and gene frequency of respective M and ABO blood groups were observed among 3 populations imported at different times.

The genetic management of the African green monkey breeding colony was discussed in relation to the difference in distribution of phenotypes of M and ABO blood groups between the parental (wild-originated) and the first filial (colony-born) populations.
Environmental ultrasound in laboratories and animal houses: a possible cause for concern in the welfare and use of laboratory animals
Authors: Sales G. D. , Wilson K. J. , Spencer K. E. V. , Milligan S. R.
Published: May 2007

Many laboratory animals are known to be sensitive to sounds (ultrasounds) beyond the nominal upper limit (20 kHz) of the human hearing range. Sources of sound in laboratories and animal houses were examined to determine the extent of ambient ultrasound. Of 39 sources monitored, 24 were found to emit ultrasonic sounds. Many of these (e.g. cage washers and hoses) also produced sound in the audible range. Running taps, squeaky chairs and rotating glass stoppers created particularly high sound pressure levels and contained frequencies to over 100 kHz. The oscilloscopes and visual display units investigated provided particular cause for concern as they emitted sounds that were entirely ultrasonic and therefore were apparently silent. Ambient ultrasound therefore appears to be common in laboratories and animal houses. It is suggested that its effect on laboratory animals should be investigated and guidelines on acceptable levels be formulated.
Four methods for general anaesthesia in the rabbit: a comparative study
Authors: Peeters M. E. , Gil D. , Teske E. , Eyzenbach V. , Brom W. E. v. d. , Lumeij J. T. , de Vries H. W.
Published: May 2007

The efficacy and safety of pentobarbitone, ketamine/xylazine, fentanyl/fluanisone/diazepam, and halothane/nitrous oxide anaesthesia were compared in 4 groups of six New Zealand White rabbits. Heart and respiratory rates, body temperature, reflexes, blood pressure and blood gases were measured.

Pentobarbitone appeared to be unsuitable for anaesthesia in rabbits, as 5 of the 6 rabbits to whom it was administered, required artificial respiration or died. The combinations of ketamine/xylazine and fentanyl-f1uanisone/diazepam both produced unpredictable levels of anaesthesia together with a substantial decline in arterial blood pressure and Po2. Despite a severe drop in blood pressure (up to 37·5%), anaesthesia with halothane and nitrous oxide was found to be superior to the other anaesthetic agents.
The extent of coprophagy in rats with differing iron status and its effect on iron absorption
Authors: Tidehag P. , Hallmans G. , Sjöström R. , Sunzel B. , Wetter L. , Wing K.
Published: May 2007

The purpose of this study was to determine the prevalence of coprophagy in rats with differing iron status and its effect on the measurement of iron absorption from test meals with and without bran. Two experiments were performed using radioisotope-labelled microspheres added as a non-digestible marker for the ingested faeces and the diet and 59Fe added as a marker for the non-haem iron in the test meal.

In this study, coprophagy occurred at group mean rates of between 5 and 22% and was independent of the iron status of the rats or the presence or absence of bran in the diet. The relative absorption of iron, measured as the retention of 59Fe from a single meal, was affected to the same extent in groups with the same iron status, if it was affected at all. Thus comparisons of iron absorption from diets with and without bran should not be affected by coprophagy.
Hazards of urethane (ethyl carbamate): a review of the literature
Authors: Field K. J. , Lang C. M.
Published: May 2007

Urethane (ethyl carbamate) is used alone or in combination with other drugs to produce anaesthesia in laboratory animals. Although originally studied as a potential phytocide, urethane demonstrated antineoplastic properties when administered to rats with the Walker rat carcinoma 256. Subsequent trials in humans led to its use as a chemotherapeutic agent for various leukaemias. Mice develop pulmonary adenomas earlier in life and at a higher incidence following urethane administration. Urethane's carcinogenic influence is greater in neonatal mice; it also has a transplacental influence in mice. In rats, urethane increases the incidence of pulmonary adenomas, Zymbal Gland tumours, and a variety of other neoplasms. Urethane is absorbed sufficiently from the skin of laboratory animals to produce a transient narcosis. The carcinogenic effect appears to be due to an undefined oncogenic intermediate formed in the blood. Considering the properties urethane demonstrates in animals, the safety of its use by laboratory personnel is in question. However, if appropriate guidelines are followed, urethane should continue to be a useful anaesthetic agent for laboratory animals.
Whole blood folate values in normal female hamsters (Mesocricetus auratus)
Authors: Macdonald D. G.
Published: May 2007

Whole blood folate estimations in adult female hamsters, using radioassay kits gave values similar to human data and comparable with previously reported serum folate levels measured using microbiological techniques.
Thyroxine (T4) and triiodothyronine (T3) levels in the Fischer 344 inbred rat
Authors: Waner T. , Nyska A.
Published: May 2007

Plasma levels of T3 and T4 were measured in male and female Fischer 344 (F344/Cr1) inbred rats aged 10, 17, 30, 56, 80 and 106 weeks in order to document the hormone profile of this strain of rat. In general, levels of T4 were higher in males than in females. Levels of T3 were lower in females for the first 17 weeks, similar for rats of age 30 weeks, and thereafter higher in the females than the males. T4 concentration decline was age-associated in both sexes. T3 levels declined in the males only, but remained relatively constant in the females throughout their lifespan. Generally, T4/T3 ratios declined throughout the lifespan of the Fischer rat.
Effects of repeated blood samplings on locomotor activity, evasion and wheel-running activity in mice
Authors: Pfeil R.
Published: May 2007

The effects of serial blood sampling on nocturnal locomotor activity, evasion, wheel-running activity and body mass were studied in male NMRI mice aged 7-8 weeks. The erythrocyte count, haematocrit and haemoglobin concentration at the beginning and end of the study showed no difference in group 1 (two samples per week, 0·08 ml each) while there was a significant decrease in the group 2 values (three samples per week, 0·08 ml each). The total amount of nocturnal locomotor activity decreased in the animals bled repeatedly while the periods with locomotor activity increased. These alterations appeared particularly after bleeding. In the test-group animals evasion showed a decrease compared with the untreated control animals, but there was no evidence of a relation to the timing of the bleedings.
Aseptic necrosis of bone in ICR mice
Authors: Yamasaki K. , Itakura C.
Published: May 2007

Aseptic bone necrosis was observed in the tibia of 23 ICR mice. Histological changes were characterized by a loss of marrow tissue with proliferation of connective tissue and bone necrosis with empty osteocytic lacunae. Focal necrosis was confined beneath the articular cartilage. Extensive necrosis was present in half or all of the epiphysis. Massive necrosis was noted in the diaphysis of one animal. It was considered that focal necrosis might be related to degenerative osteoarthritis, and that extensive and massive necroses might have been caused by a disturbance of the blood supply.
Allelic profile at 37 biochemical loci of two inbred strains of the house mouse derived from wild Mus musculus musculus
Authors: Von Deimlingi O. H. , Forejt J. , Wienker T. F.
Published: May 2007

Two newly established inbred strains derived from Mus musculus musculus, designated PWD/Ph (F29) and PWK/Ph (F33), were examined for their alleles at 37 biochemical loci located on 12 different chromosomes. The allelic pattern showed characteristic differences from those observed in common inbred strains. The genetic distance D between PWK/Ph and PWD/Ph was 0·027, whereas the corresponding values for the genetic distances between PWK/Ph and C57BL/6J, DBA/2J, BALB/cJ and SWR/J were 0·777, 0·721, 0·721 and 0·838 respectively. New allozymes are described as being controlled by the loci Es-23, Pre-2 and Tam-1. The genetic relationship to M.m. molossinus is indicated by identical alleles at six other loci ( Es-2, Es-9, Es-10, Es-11, Es-18 and Es-22).
Alloxan-induced diabetes mellitus in pregnant sheep and chronic fetal catheterization
Authors: Lips J. P. , Jongsma H. W. , Eskes T. K. A. B.
Published: May 2007

25 female sheep of the Texel breed were made hyperglycaemic by administration of alloxan monohydrate (ALX) in early pregnancy and 15 ewes served as controls. Average venous glucose levels (mean ± standard deviation) increased from 3·5 ± 0·2 to 14·0 ± 1·8 mmol/l. All hyperglycaemic sheep were treated with long-acting insulin in doses adjusted individually (0·2-1·0 U/kg per day) to keep glucose levels above 8 mmol/l. After a temporary significant increase, maternal venous concentrations of urea and creatinine returned to normal levels.

One sheep died on day 6 after administration of ALX. Another hyperglycaemic sheep died at induction of anaesthesia. Eight hyperglycaemic ewes aborted between days 90 and 128 of gestation. Between days 103 and 135 of gestation the remaining hyperglycaemic ( n = 15) and control ( n = 15) ewes were operated upon and the fetuses were provided with EEG, nuchal EMG and ECG electrodes and catheters in the trachea, amniotic fluid, jugular vein and carotid artery.

Use of the chronic sheep preparation for the study of diabetes mellitus and fetal reactions was successful in 10 out of 25 cases, as in the diabetic group postoperative intra-uterine fetal survival varied between 2 and 19 days and in 10 cases was at least 5 days. Postoperative intra-uterine fetal survival in the controls was significantly longer and varied between 4 and 28 days, and in 13 cases was at least 5 days.

A highly significant correlation ( P < 10-6) between maternal and fetal blood glucose levels was seen. After 5 days of postoperative recovery fetal blood glucose levels were 3·8 ± 1·3 mmol/l in the hyperglycaemic group compared with 0·5 ± 0·2 mmol/l in the control group. The fetal clinical condition as measured by fetal arterial blood gases did not differ significantly between the hyperglycaemic and control groups. Fetal plasma insulin levels in the hyperglycaemic group did not differ significantly from the control group levels. The birth-weights of the fetuses of the ALX-treated sheep were significantly lower compared with control fetuses.
The initiation and maintenance of a colony of coccidia-free wood mice (Apodemus sylvaticus)
Authors: Higgs S. , Nowell F. , Ibrahim S. A. M.
Published: May 2007

Wood mice from a population showing enzootic infection with Eimeria were trapped and bred under laboratory conditions. The maintenance regime, which freed the animals from coccidia, and the breeding procedures used over several generations are described and discussed.