bluuebunny/crossref_metadata_2025_split huggingface dataset:
A theory for flame extinction based on flame temperature
Authors: Quintiere J. G. , Rangwala A. S. 
Published: April 2004

AbstractThe extinction and suppression of diffusion flames is examined theoretically. The effects of oxygen reduction and external heat flux are examined compared to data in the literature. An application of extinction in compartment fires is also examined. The theory developed is based on a critical flame temperature, and that theory includes transient effects and the addition of water as well. Copyright © 2004 John Wiley & Sons, Ltd.
Stability of lightweight structural sandwich panels exposed to fire
Authors: Cooke Gordon M. E. 
Published: April 2004

AbstractSandwich panels comprising thin flat metal faces and a lightweight structural core are increasingly used as walls and ceilings in buildings where their long‐span capabilities, high thermal insulation, clean design, rapid installation and low maintenance often make them the preferred choice of designers and building owners.The fire performance of sandwich panels can be excellent if the correct core material is used and, importantly, if the metal facings are adequately restrained. For example, fire resistance in excess of 2 h can be easily achieved using panels with sheet steel faces and a non‐combustible rock wool core.Where sandwich panels are used in cold stores there is the potential problem of cold‐bridging between the facings wherever there is a metallic through‐fixing, and this has led to designs which work well in normal conditions but allow panels to collapse very early when exposed to fire because the facings are not tied back to the supporting structure. Such collapse is a fire hazard to fire‐fighters as proven in the 1993 fire in the Sun Valley poultry factory in Hereford, United Kingdom in which two firemen lost their lives.The paper describes what can happen if panel facings are not mechanically restrained with steel fastenings. It then introduces a fire safety engineering method for assessing the stability of ceiling sandwich panels exposed to fire. The method assumes that the ends of panels are restrained and the panel behaves as a catenary after delamination. The paper quantifies the variation of catenary force as fire develops and takes account of the initial beneficial sag which is present at the time of delamination. The method is currently being considered in the work of European committee CEN TC 127 on the development of rules for extended applications for construction products. Copyright © 2004 John Wiley & Sons, Ltd.
Fire resistance of structural components protecting escape routes
Authors: Thomas Geoff , Lloydd Delwyn 
Published: April 2004

AbstractGenerally, fire resistant structures are expected to survive a fire in an adjoining compartment. Some structures, such as floors, may be designed to provide time for the occupants to escape from compartments other than the one where the fire occurs. In the fire compartment smoke development governs the time available for egress. A common misconception is that the fire resistance rating (FRR), the time an assembly will survive in a test furnace, is the time available to escape. In small compartments such as those in residential accommodation their FRR is significantly longer than the times the assemblies would survive in real compartment fires. Some fire engineering designs for retrofitted accommodation buildings use FRR times for light timber frame walls and floors as the available egress time, which is unconservative.The method of time equivalence can provide a prediction of the FRR required to survive a compartment burnout. The ratio of the total burning time of the fire to the time equivalent for the compartment and fuel load can be used to provide an estimate of the time taken for an assembly of given fire resistance to fail by multiplying the FRR by the ratio. Although this method is shown to be non‐conservative when a computer model of light timber frame wall assemblies is run using both realistic time‐temperature curves and the ISO‐834 standard fire test time‐temperature curve, it is more conservative than assuming that an assembly will last as long in a compartment fire as predicted by the FRR. Copyright © 2004 John Wiley & Sons, Ltd.
Bending and membrane action in concrete slabs
Authors: Gillie Martin , Usmani Asif , Rotter Michael 
Published: April 2004

AbstractIt has become apparent from the series of fire tests carried out at Cardington, UK that the response of steel‐concrete composite structures in fire conditions is largely governed by the behaviour of the reinforced concrete floor slabs. This paper obtains a detailed understanding of the strength of heated concrete floor slabs when subject to the combined bending and membrane forces that typically result from restrained thermal expansion. To analyse such slabs the computer program FEAST is used. Initially the behaviour of the floor slab in the Cardington frame under pure bending and pure membrane forces is described and explained. The paper then explores the effect that interaction between bending and membrane behaviour has on the strength of the slab when it is uniformly heated, heated with a linear thermal gradient and heated with the non‐linear thermal gradient observed during the Cardington tests. Finally, the effects of varying the area and location of the reinforcement in the slab are analysed. Copyright © 2004 John Wiley & Sons, Ltd.
Structural behaviour of an open car park under real fire scenarios
Authors: Zhao Bin , Kruppa Joël 
Published: April 2004

AbstractDuring two successive European research projects involving CTICM (France), ARBED (Luxembourg) and TNO (Netherlands), several fire tests were performed on cars and on a real car park made of steel columns and steel beams connected to composite slabs. Although there has been a drastic increase of combustible product in cars, the experimental results have given convincing evidence that fire protection of the steel structure is not necessary to obtain overall stability.Parallel to the above experimental investigations, numerical analysis was also performed in which the fire development, the heating of the structure and structural behaviour during the fire were studied with different numerical models. However, the present paper focuses mainly on the modelling of structural behaviour. It shows that the global structural behaviour (composite floor and steel column) subjected to localized heating from cars may be very accurately predicted by 3D modelling in which the lateral buckling of the steel beam, the membrane and diaphragm effects of the floor are taken into account.In addition, the results of a parametric study are presented in which it is shown that the use of 3D modelling in the analysis leads to the possibility of building open car parks with more economical steel and concrete composite structures. Copyright © 2004 John Wiley & Sons, Ltd.
A Review of Mathematical Models for Hydrogen and Direct Methanol Polymer Electrolyte Membrane Fuel Cells
Authors: Yao K.Z. , Karan K. , McAuley K.B. , Oosthuizen P. , Peppley B. , Xie T. 
Published: April 2004

AbstractThis paper presents a review of the mathematical modeling of two types of polymer electrolyte membrane fuel cells: hydrogen fuel cells and direct methanol fuel cells. Models of single cells are described as well as models of entire fuel cell stacks. Methods for obtaining model parameters are briefly summarized, as well as the numerical techniques used to solve the model equations. Effective models have been developed to describe the fundamental electrochemical and transport phenomena occurring in the diffusion layers, catalyst layers, and membrane. More research is required to develop models that are validated using experimental data, and models that can account for complex two‐phase flows of liquids and gases.
Modeling the Effects of Methanol Crossover on the DMFC
Authors: Zhang J. , Wang Y. 
Published: April 2004

AbstractA mathematic model is established to simulate the effects of methanol crossover on the DMFC. The transport and reactions of both oxygen and methanol at the cathode are described and the theory of “parallel electrode reactions” is applied to calculate the cathode over‐potential caused by methanol crossover. The influence of methanol concentration, fuel cell temperature, oxygen pressure, and membrane properties on the cathode over‐potential is evaluated. Simulation results show that methanol crossover considerably increases the cathode over‐potential at low current density, but its effect is significantly reduced when the current density is increased to reasonable values. It also shows that of the two parameters characterizing a polymer electrolyte membrane, proton conductivity and methanol permeability, the former has more impact on the performance of a DMFC.
Novel CVD Techniques for Micro‐ and IT‐SOFC Fabrication
Authors: Meng G. , Song H. , Xia C. , Liu X. , Peng D. 
Published: April 2004

AbstractAt present, there are intensive research efforts towards intermediate temperature solid oxide fuel cells (IT‐SOFCs) with a thin film electrolyte and electrode. In view of the nature of molecular level reaction and the great potential of CVD processes for IT‐SOFCs and even Micro‐SOFC fabrication, various novel CVD techniques have been developed to prepare multi‐component oxide films and multi‐layers related to the SOFC. In this paper, novel CVD techniques are described and reviewed for possible applications in thin film electrolytes and electrodes for SOFCs, mainly based on the research activities of the author's laboratory. The techniques include metal‐organic CVD (MOCVD) with metal β‐diketonate chelates as precursors, single mixed source MOCVD, and aerosol assisted CVD (AACVD). AACVD can be operated with spray AAMOCVD, plasma‐AACVD, or oxy‐acetylene combustion AACVD. The results show their possible application in the fabrication of electrolyte and electrode thin films for SOFCs.
Development of Solid Oxide Fuel Cells by Applying DC and RF Plasma Deposition Technologies
Authors: Schiller G. , Henne R. , Lang M. , Müller M. 
Published: April 2004

AbstractBased on advanced plasma deposition technology with both DC and RF plasmas DLR Stuttgart has developed a concept of a planar SOFC with consecutive deposition of all layers of a thin‐film cell onto a porous metallic substrate support. This concept is an alternative approach to conventionally used sintering techniques for SOFC fabrication without needing any sintering steps or other thermal post‐treatment. Furthermore, is has the potential to be developed into an automated continous production process. For both stationary and mobile applications, adequate stack designs and stack technologies have been developed. Future development work will focus on light‐weight stacks to be applied as an Auxillary Power Unit (APU) for on‐board electricity supply in passenger cars and airplanes.This paper describes the plasma deposition technologies used for cell fabrication and the DLR spray concept including the resulting stack designs. The current status of development and recent progress with respect to materials development and electrochemical characterization of single cells and short‐stacks is presented.
A Study of Thermal Transient Performances of Molten Carbonate Fuel Cells
Authors: Weng S. , Weng Y. , Su M. , Zhang H. 
Published: April 2004

AbstractBased on the conservation of energy and conservation of mass, as well as considering the mass transfer in the electrodes‐electrolyte interface and its effect on Molten Carbonate Fuel Cell (MCFC) thermal characteristics, this paper presents a mathematical model to modify the dynamic performance of MCFC. Using the method of weighted residuals (MWR) which possesses high precision for the solution of partial differential equations, and the Matlab system function which is efficient for numerical resolution and simulation, a dynamic simulation model of MCFC is created. The results of the simulation show that the mass transfer in the electrodes‐electrolyte interface notably affects Molten Carbonate Fuel Cell (MCFC) thermal characteristics, and there is a distribution of temperature both in the electrodes‐electrolyte and in the fuel gas as well as in the oxidant gas. The temperature of electrodes‐electrolyte increases and that of oxidant gas decreases with increments in the flow rate of both the fuel gas and oxidant gas.
Experimental Investigation of Effect of Flow Bed Design on Performance of Liquid Feed Direct Methanol Fuel Cells
Authors: Guo H. , Ma C.F. , Wang M.H. , Ye F. , Yu J. , Wang Y. , Wang C.Y. 
Published: April 2004

AbstractThe effect of flow bed design on the performance of a liquid feed direct methanol fuel cell was studied experimentally. The flow beds were designed and manufactured with different channel densities, channel depths, and ridge widths. The flow beds were machined on stainless steel polar plates. The experimental results showed that ridge width affects the slope of the ohmic polarization curve. A ridge width of 3.30 mm provided the highest peak power. When the contact surface area between the flow bed and electrode was constant, the effect of channel density on cell performance was minimal, under the experimental conditions of this paper. The channel depth had a considerable influence on cell performance with a 2 mm deep channel achieving the best performance. The mechanism of the experimental phenomena was analyzed in this paper.
Cross‐Linked Polyaryl Blend Membranes for Polymer Electrolyte Fuel Cells
Authors: Kerres J. , Ullrich A. , Hein M. , Gogel V. , Friedrich K.A. , Jörissen L. 
Published: April 2004

AbstractThe preparation and characterization of different types of proton‐conducting polymer blend membranes are presented in this paper. The investigations are focused on the determination of the thermal stability of the membranes, because thermal stability is one of the important parameters for the application of the membranes in polymer electrolyte fuel cells. In addition to the thermal stability, chemical stability, proton conductivity and mechanical strength are required. The characterization of the membranes was performed by thermogravimetry (TGA), a combined TGA and FTIR analysis where infrared spectroscopy is used for the determination of decomposition products, and experiments on the dependence of water uptake (swelling) of the membranes on temperature. Ionically cross‐linked membranes have been investigated. The TGA‐FTIR coupling experiments showed clearly, that the decomposition of the membranes starts at ≈ 230 °C, and that in some cases the principal membrane component which is sulfonated polyaryletherketone splits off SO2 at slightly lower temperature in the membrane than in the pure substance. Most of the other polymeric components of the blend membranes were slightly more stable in the membrane than in the pure form. The ionically cross‐linked membranes were tested in direct methanol fuel cells as well as in a H2/air fuel cell and exhibit a performance which compares favorably with standard membranes.
CD44 overexpression by oligodendrocytes: A novel mouse model of inflammation‐independent demyelination and dysmyelination
Authors: Tuohy Therese M.F. , Wallingford Nicholas , Liu Ying , Chan Frank H. , Rizvi Tilat , Xing Rubing , Bebo Bruce , Rao Mahendra S. , Sherman Larry S. 
Published: April 2004

AbstractThe CD44 transmembrane glycoprotein family has been implicated in cell‐cell adhesion and cell signaling in response to components of the extracellular matrix but its role in the nervous system is not understood. CD44 proteins are elevated in Schwann cells and oligodendrocytes following nervous system insults, in inflammatory demyelinating lesions, and in tumors. Here, we tested the hypothesis that elevated CD44 expression influences Schwann cell and oligodendrocyte functions by generating transgenic mice that express CD44 under the control of the 2′,3′‐cyclic nucleotide‐3′‐phosphodiesterase (CNPase) promoter. These mice failed to develop peripheral nerve or CNS tumors. However, they did develop severe tremors that were associated with CNS dysmyelination and progressive demyelination. Loss of CNS myelin was not due to alterations in early oligodendrocyte precursor differentiation, proliferation, or survival. Myelination in the PNS appeared normal. In no instance was there any evidence of an inflammatory response that could account for the loss of CNS myelin. These findings suggest that CNPase‐CD44 mice are a novel model for noninflammatory progressive demyelinating disease and support a potential role for CD44 proteins expressed by glial cells in promoting demyelination. © 2004 Wiley‐Liss, Inc.
Activation of P2 nucleotide receptors stimulates acid efflux from astrocytes
Authors: Dixon S. Jeffrey , Yu Rongguo , Panupinthu Nattapon , Wilson John X. 
Published: April 2004

AbstractAcidification of the extracellular fluid modulates neurotransmission and ischemic injury in brain. The purpose of the present study was to investigate the effects of purine and pyrimidine transmitters on acid efflux from brain astrocytes. Using RT‐PCR, we detected transcripts for the following nucleotide receptors in rat primary astrocyte cultures: P2X1, P2X2, P2X3, P2X4, P2X6, P2X7, P2Y1, P2Y2, P2Y4, and P2Y6. Adenosine 5′‐triphosphate (ATP) was found to rapidly induce a biphasic increase in acid efflux, monitored by microphysiometry, consisting of an initial transient and a sustained plateau. Compared with ATP, the P2Y agonist uridine 5′‐triphosphate (UTP) induced a much smaller initial response but an equal plateau. The poorly hydrolyzable ATP analogue ATPγS caused the same initial response as did ATP, but a much smaller plateau, suggesting that the latter phase was due to extracellular degradation of nucleotides. The P2 receptor antagonist, suramin, blocked stimulation of acid efflux by ATP. Removal of extracellular glucose or elevation of extracellular K+ decreased the basal rate of acid efflux but not the stimulation induced by ATP. Inhibition of Na+/H+ exchange by cariporide suppressed the initial phase of ATP‐stimulated acid efflux. The intracellular Ca2+ chelator bisaminophenoxyethane‐ tetraacetic acid (BAPTA) lowered basal acid efflux and abolished the initial phase of the response to ATP. In conclusion, ATP acts through P2 nucleotide receptors on astrocytes to stimulate the Ca2+‐dependent efflux of protons, mediated in part by activation of Na+/H+ exchange. The resulting acidification of the extracellular fluid may serve as an intercellular signal in brain. © 2004 Wiley‐Liss, Inc.
Reversible disruption of tight junction complexes in the rat blood‐brain barrier, following transitory focal astrocyte loss
Authors: Willis Colin L. , Leach Lopa , Clarke Garry J. , Nolan Christopher C. , Ray David E. 
Published: April 2004

AbstractBreakdown of the blood‐brain barrier is a feature of acute and chronic neurodegenerative changes, yet the relationship between astrocytes and the mature barrier remains unclear. We studied this role of astrocytes in vivo using a gliotoxin and evaluated changes in three vascular tight junction markers. Male Fisher F344 rats given systemic 3‐chloropropanediol showed astrocytic loss in the inferior colliculus from 12–24 h until the lesion was repopulated 8–28 days later. Within 6 h of astrocyte loss, microvessels in this area began to demonstrate a loss of the normal paracellular localization of the transmembrane proteins occludin and claudin‐5 and cytoplasmic zonula occludens‐1, which correlated with focal vascular leak of dextran (10 kDa) and fibrinogen. Platelet endothelial adhesion molecule‐1 staining revealed that there was no loss of the endothelial lining. Between 4–8 days, severe downregulation of tight junction protein expression was observed, which subsequently returned over the same time period as astrocytes repopulated the lesion. Unexpectedly, dextran and fibrinogen leak from vessels had ceased at 6 days, well before the return of occludin and claudin‐5 to appropriate paracellular domains. Control nonvulnerable cortical tissue showed no change in astrocyte morphology and tight junction expression over the same time course. Our data supports a primary role for astrocytic contact in the expression of occludin, claudin‐5, and zonula occludens‐1 in the mature brain vasculature in vivo. However, barrier integrity to dextran (10 kDa) and fibrinogen can be restored in the absence of astrocytes and tight junction proteins (occludin, claudin‐5, and zonula occludens‐1). © 2004 Wiley‐Liss, Inc.
Model of frequent, recurrent, and spontaneous seizures in the intact mouse hippocampus
Authors: Derchansky M. , Shahar E. , Wennberg R.A. , Samoilova M. , Jahromi S.S. , Abdelmalik P.A. , Zhang L. , Carlen P.L. 
Published: April 2004

AbstractThis study presents a model of chronic, recurrent, spontaneous seizures in the intact isolated hippocampal preparation from mice aged P8–P25. Field activity from the CA1 pyramidal cell layer was recorded and recurrent, spontaneous seizure‐like events (SLEs) were observed in the presence of low Mg2+ (0.25 mM) artificial cerebrospinal fluid (ACSF). Hippocampi also showed interictal epileptiform discharges (IEDs) of 0.9–4.2 Hz occurring between seizures. No age‐specific differences were found in SLE occurrence (2 SLEs per 10 min, on average), duration, and corresponding frequencies. After long exposure to low Mg2+ ACSF (>3 h), SLEs were completely reversible within minutes with the application of normal (2 mM Mg2+) ACSF. The AMPA antagonist, CNQX, blocked all epileptiform activity, whereas the NMDA antagonist, APV, did not. The γ‐aminobutyric acid (GABA)A antagonist, bicuculline, attenuated and fragmented SLEs, implicating interneurons in SLE generation. The L‐type Ca2+ blocker, nifedipine, enhanced epileptiform activity. Analysis of dual site recordings along the septotemporal hippocampus demonstrated that epileptiform activity began first in the temporal pole of the hippocampus, as illustrated by disconnection experiments. Once an SLE had been established, however, the septal hippocampus was sometimes seen to lead the epileptiform activity. The whole hippocampus with intact local circuitry, treated with low Mg2+, provides a realistic model of recurrent spontaneous seizures, which may be used, in normal and genetically modified mice, to study the dynamics of seizures and seizure evolution, as well as the mechanisms of action of anti‐epileptic drugs and other therapeutic modalities. © 2004 Wiley‐Liss, Inc.