bluuebunny/crossref_metadata_2025_split huggingface dataset:
Generation of fragility curves for Turkish masonry buildings considering in‐plane failure modes
Authors: Erberik M. Altuğ 
Published: September 2007

AbstractThis study focuses on the seismic safety evaluation of masonry buildings in Turkey for in‐plane failure modes using fragility curves. Masonry buildings are classified and a set of fragility curves are generated for each class. The major structural parameters in the classification of masonry buildings are considered as the number of stories, load‐bearing wall material, regularity in plan and the arrangement of walls (required length, openings in walls, etc.), in accordance with the observations from previous earthquakes and field databases. The fragility curves are generated by using time history (for demand) and pushover (for capacity) analyses. From the generated sets of fragility curves, it is observed that the damage state probabilities are significantly influenced from the number of stories and wall material strength. In the second stage of the study, the generated fragility curves are employed to estimate the damage of masonry buildings in Dinar after the 1995 earthquake. The estimated damage by fragility information is compared with the inspected
visual damage as assessed from the Damage Evaluation Form. For the quantification of fragility‐based damage, a single‐valued index, named as ‘vulnerability score’ (VS), is proposed. There seems to be a fair agreement between the two damage measures. In addition to this, decisions regarding the repair or demolition of masonry buildings in Dinar due to visual damage inspection are on comparable grounds with the relative measure obtained from VS of the same buildings. Hence, the fragility‐based procedure can provide an alternative for the seismic safety evaluation of masonry buildings in Turkey. Copyright © 2007 John Wiley & Sons, Ltd.
A multilevel domain decomposition approach to solving coupled applications in computational fluid dynamics
Authors: Aulisa Eugenio , Manservisi Sandro , Seshaiyer Padmanabhan 
Published: September 2007

AbstractDirect numerical simulation of the non‐linear equations, governing a fluid–structure system, relies heavily on the properties of the coupled system and the corresponding iterative solver. The purpose of this paper is to introduce a flexible and robust multilevel finite element algorithm that can be used to study the behavior of a fully coupled fluid–structure system. The method relies on the domain decomposition characteristics of the multigrid Vanka solvers, which decompose the complex global domain into the finite element local sub‐domains and then compute the global solution iteratively. This particular methodology allows us to solve easily this coupled system over a fluid–solid domain which consists of a set of subdomains from different mesh levels with conforming or non‐conforming finite element method approximations. The multigrid projection and restriction operators are used to impose the matching between the extended fluid and solid velocity field. Copyright © 2007 John Wiley & Sons, Ltd.
Improvements in speed for explicit, transient compressible flow solvers
Authors: Löhner Rainald , Luo Hong , Baum Joseph D. , Rice Darren 
Published: September 2007

AbstractSeveral explicit high‐resolution schemes for transient compressible flows with moving shocks are combined in such a way so as to achieve the highest possible speed without compromising accuracy. The main algorithmic changes considered comprise the following:

replacing limiting and approximate Riemann solvers by simpler schemes during the initial stages of Runge–Kutta solvers, and only using limiting and approximate Riemann solvers for the last stage;
automatically switching to simpler schemes for smooth flow regions;
automatic deactivation of quiescent regions; and
unstructured grids with cartesian cores or embedded cartesian grids.
The results from several examples demonstrate that speedup factors of 1:4 are attainable without compromising the accuracy of the traditional FCT schemes. Copyright © 2007 John Wiley & Sons, Ltd.
Simulation of liquid sloshing in curved‐wall containers with arbitrary Lagrangian–Eulerian method
Authors: Zhou H. , Li J. F. , Wang T. S. 
Published: September 2007

AbstractThere are many challenges in the numerical simulation of liquid sloshing in horizontal cylinders and spherical containers using the finite element method of arbitrary Lagrangian–Eulerian (ALE) formulation: tracking the motion of the free surface with the contact points, defining the mesh velocity on the curved wall boundary and updating the computational mesh. In order to keep the contact points slipping along the curved side wall, the shape vector in each time advancement is defined to modify the kinematical boundary conditions on the free surface. A special function is introduced to automatically smooth the nodal velocities on the curved wall boundary based on the liquid nodal velocities. The elliptic partial differential equation with Dirichlet boundary conditions can directly rezone the inner nodal velocities in more than a single freedom. The incremental fractional step method is introduced to solve the finite element liquid equations. The numerical results that stemmed from the algorithm show good agreement with experimental phenomena, which demonstrates that the ALE method provides an efficient computing scheme in moving curved wall boundaries. This method can be extended to 3D cases by improving the technique to compute the shape vector. Copyright © 2007 John Wiley & Sons, Ltd.
A reduced model of the Madden–Julian oscillation
Authors: Wedi Nils P. , Smolarkiewicz Piotr K. 
Published: September 2007

AbstractWe have extended our virtual laboratory for internal wave motions (Int. J. Numer. Meth. Fluids 2005; 47:1369–1374) to the case of rotating fluids on an equatorial β‐plane. A virtual wave‐maker is introduced via a time‐dependent coordinate transformation in the meridional direction, represented by two lateral boundary meanders. The technique is consistently incorporated into the numerical algorithm of the nonhydrostatic model EULAG. The modelling framework is applied in simulations of equatorial wave motions to enhance our understanding of the Madden–Julian oscillation (MJO). The simulation of a realistic MJO in global circulation and climate models is a continuing challenge—in part, due to the failure of existing theories to explain the ubiquitous modelling difficulties of the phenomenon. Virtual laboratory experiments appear ideal complementary tools to isolate and study particular geophysical flow structures. In
these laboratory‐scale ‘climate’ simulations we observe eastward propagating low‐frequency horizontal structures consistent with Rossby solitary wave theory, representing a particular solution of the Korteweg–de Vries equation for the evolution of the wave amplitude under a given forcing. The latter extends the linear shallow water theory—commonly used to explain different modes of equatorial wave motions—to the weakly nonlinear regime. One important outcome of our simulations is the finding that these structures depend on strong stratification, and may be easily destroyed or weakened if substantial near‐surface perturbations and associated vertical motions exist. This could play a role in the failure to simulate a realistic MJO, but it may also provide an explanation why solitary waves are not as readily observed in oceans as they are in models and theory. Ultimately, our research aims at constructing a simplified dynamical apparatus to reproduce MJO‐like structures in a laboratory analogue, in the spirit of the Plumb–McEwan experiment for the quasi‐biennial oscillation and vis‐a‐vis its numerical equivalent. Copyright © 2007 John Wiley & Sons, Ltd.
Studies of Material Interaction After Long‐Term Stack Operation
Authors: Menzler N. H. , Batfalsky P. , Blum L. , Bram M. , Groß S. M. , Haanappel V. A. C. , Malzbender J. , Shemet V. , Steinbrech R. W. , Vinke I. 
Published: September 2007

AbstractForschungszentrum Jülich is routinely operating solid oxide fuel cells (SOFCs) in stacks of planar design. Anode‐supported cells are used in combination with ferritic steel interconnects as standard components. The stacks are typically sealed with glass‐ceramics. In order to examine the long‐term interaction between the materials comprising these components, and the contact and protection layers, SOFC stacks with operation times of more than 6,000 h at 800 °C have been disassembled and microstructurally examined. The stack disassembling and examination procedures are outlined and results from optical and scanning electron microscopy are presented. Two interaction observations that are considered to affect stack performance are addressed in detail. The effects refer to the reaction of the glass‐ceramic sealant with the ferritic steel interconnect and to Cr deposition at the cathode/electrolyte interface. Measures and strategies to diminish and/or to prevent unwanted long‐term material interactions are discussed.
Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study
Authors: Tsai C.‐E. , Hwang B.‐J. 
Published: September 2007

AbstractThe intermolecular interactions between methanol/water and Nafion™ membranes have been investigated using IR spectroscopy. The evolution of IR spectra of the Nafion™ membranes, immersed in various concentrations of methanol solution depends strongly on the methanol concentration. The O–H bending vibration modes at 1,636, 1,660 and 1,672 cm–1 associated with the hydrogen bonding of (H3O+…SO3–) as well as (CH3OH2+…SO3–), and at 1,702, 1,717 and 1,711–1,736 cm–1 associated with the hydrogen bonding of (CF2…H–O–CH3), (CF2…H–OH), (CF2…+H3O) and (CF2…H–OSO2–) were observed. The vibration mode of (CF2…H–O) was found to be appearing obviously at 3,821–3,900 cm–1 when the Nafion™ membrane was immersed in the methanol solution with concentration higher than 6 M. On the other hand, the wavenumber of the O–H stretching peak increases with an increase in the methanol concentration. Results of IR spectra revealed that the methanol molecules show better capability to penetrate into the hydrophobic domain of the Nafion™ membrane than water. The intermolecular interaction between the hydrophobic domains of Nafion™ and methanol molecules becomes more observable at a higher methanol concentration.
Characterisation of Ni–YSZ‐Cermets with Respect to Redox Stability
Authors: Ettler M. , Blaß G. , Menzler N. H. 
Published: September 2007

AbstractIn anode‐supported solid oxide fuel cells (SOFCs), air break‐in on the anode side can result in reoxidation of metallic nickel. The volume expansion caused by Ni oxidation generates stresses within the substrate, the anode and the electrolyte. Those stresses exceed the stability of the components, potentially promoting crack growth. Therefore, either the SOFC degrades continuously after each redox‐cycle or the membrane electrode assembly (MEA) fails completely if the electrolyte cracks.The influence of several reoxidation parameters on the mechanical integrity of Ni–YSZ‐anodes after reoxidation was investigated using different types of samples. All samples were SFEs (substrate–functional layer–electrolytes), consisting of Ni–YSZ‐substrate, Ni–YSZ‐anode and YSZ‐electrolyte. Investigations were carried out on freestanding SFEs and SFEs attached to steel plates (Crofer22APU, Thyssen Krupp V. D. M., Material Data Sheet No. 4046, Edition of December 2006) with a glass sealing.The results show a big influence of the degree of oxidation, homogeneity of oxidation, the operating temperature and the incident flow on the behaviour and the mechanical integrity of the reoxidised SFEs. The time of oxidation and the gas flow rate were influencing parameters, whereas the influence of the porosity was insignificant. The behaviour of the SFEs upon reoxidation also changes dramatically when comparing freestanding samples with attached samples.
Dynamic Modelling of a Polymer Electrolyte Membrane Fuel Cell Stack by Nonlinear System Identification
Authors: Buchholz M. , Krebs V. 
Published: September 2007

AbstractReal‐time models of polymer electrolyte membrane fuel cell (PEMFC) stacks with high accuracy are required, e.g. for the design of controllers or online diagnosis tools. By using physical and chemical laws representing the processes in a PEMFC stack, very detailed, but computationally complex models can be retrieved.In this paper, a nonlinear dynamic model obtained by system identification is proposed for PEMFC stacks. The model structure in this contribution is based on a modular concept and is divided into a static and a dynamic part. The static part represents the stationary points and the dynamic part describes the deviation from these stationary points due to changes in the input signals. Both parts can be modelled by different methods. A characteristic map and a neural network (NN) are proposed for the static part. For the dynamic part, transfer functions and a linear state‐space model retrieved by canonical variate analysis (CVA) are investigated.
Mutations in the ataxia telangiectasia and rad3‐related–checkpoint kinase 1 DNA damage response axis in colon cancers
Authors: Lewis Kriste A. , Bakkum‐Gamez Jamie , Loewen Ralitsa , French Amy J. , Thibodeau Stephen N. , Cliby William A. 
Published: September 2007

AbstractIn response to certain types of DNA damage, ataxia telangiectasia and rad3‐related (ATR) phosphorylates checkpoint kinase 1 (CHEK1) resulting in cell cycle arrest and subsequent DNA repair. ATR and CHEK1 contain mononucleotide microsatellite repeat regions, which are mutational targets in tumors with defective mismatch repair (MMR). This study examined the frequency of such mutations in colon cancers and their impact on biologic behavior. Screening for ATR mutations in 48 tumors was performed using denaturing high‐performance liquid chromatography (DHPLC) and confirmed with sequencing analysis. The CHEK1 exon 7 A(9) region was sequenced in 20 of the 27 (74%) tumors with high frequency of microsatellite instability (MSI‐H). Univariate and multivariate analyses were used to examine associations with clinical outcomes. Frequent mutations in MSI‐H colon cancers were identified within the ATR (37%)/CHEK1(5%) damage response pathway. Stage and MSI status both independently predicted overall survival (OS) and disease‐free survival (DFS). ATR status was not associated with stage, but was associated with a trend toward improved DFS: 0/9 cancers recurred in MSI‐H cases harboring ATR mutations vs. 4/18 recurrences in MSI‐H cases without ATR mutations. This suggests that ATR mutations may affect clinical behavior and response to therapy in MSI‐H colon cancers. © 2007 Wiley‐Liss, Inc.
Effects of exercise on NMDA receptor subunit contributions to bidirectional synaptic plasticity in the mouse dentate gyrus
Authors: Vasuta Cristina , Caunt Charlotte , James Rachel , Samadi Shervin , Schibuk Elizabeth , Kannangara Timal , Titterness Andrea K. , Christie Brian R. 
Published: September 2007

AbstractWe examined synaptic plasticity in the dentate gyrus (DG) of the hippocampus in vitro in juvenile C57Bl6 mice (28–40 days of age), housed in control conditions with minimal enrichment (Controls) or with access to an exercise wheel (Runners). LTP expression was significantly greater in slices from Runners than in those from Controls, but could be blocked by APV in both groups. LTP was significantly reduced by NR2B subunit antagonists in both groups. NVP‐AAM077, an antagonist with a higher preference for NR2A subunits over NR2B subunits, blocked LTP in slices from Runners and produced a slight depression in Control animals. LTD in the DG was also blocked by APV, but not by either of the NR2B specific antagonists. Strikingly, NVP‐AAM077 prevented LTD in Runners, but not in Control animals, suggesting an increased involvement of NR2A subunits in LTD in animals that exercise. NVP‐AAM077 did not block LTD in NR2A Knock Out (KO) animals that exercised, as expected. In an attempt to discern whether NMDA receptors located at extrasynaptic sites could play a role in the induction of LTD, DL‐TBOA was used to block excitatory amino acid transport and increase extracellular glutamate levels. Under these conditions, LTD was not blocked by the co‐application of a specific NR2B subunit antagonist in either group, but NVP‐AAM077 again blocked LTD selectively in Runners. These results indicate that NR2A and NR2B subunits play a significant role in LTP in the DG, and that exercise can significantly alter the contribution of NMDA NR2A subunits to LTD. © 2007 Wiley‐Liss, Inc.
Functional dissociation between fornix and hippocampus in spatial conditional learning
Authors: Dumont J. , Petrides M. , Sziklas V. 
Published: September 2007

AbstractDo lesions of the fornix or the hippocampus impair the performance of spatial conditional associative learning tasks, and to what extent does damage to these brain structures result in comparable deficits in this type of spatial behavior? The available evidence is not clear. In the present study, rats with lesions of the fornix, hippocampus, and normal control animals were trained on two spatial–visual conditional learning tasks in which they had to form arbitrary associations between visual stimuli and the context in which these stimuli were embedded. In one condition, rats were required to choose stimulus X in place A and stimulus Y in place B, and there was no overlap in the contents of the two scenes. In the other condition, the animal approached the same scene from two different directions and had to select stimulus X when the scene was viewed from perspective A and to select stimulus Y when the scene was viewed from perspective B. Rats with fornix transection were able to learn both conditional tasks at a rate comparable to that of normal control animals, but rats with hippocampal damage were severely impaired under both conditions. The findings extend the range of tasks known to be sensitive to damage of the hippocampus. In addition, the results argue that the fornix is not necessary for the acquisition of certain spatial conditional learning tasks and that this brain structure cannot be used as an indicator of hippocampal dysfunction under all learning situations. © 2007 Wiley‐Liss, Inc.
Biocompatibility testing of simulated total joint arthoplasty articulation debris
Authors: Anabtawi Mona , Beck Preston , Lemons Jack 
Published: September 2007

AbstractSurface characterization was performed to evaluate the surface condition of an uncoated cobalt alloy disc (control), and discs with medium and thick boron coatings for total joint articulating surfaces. Discs were characterized by scanning electron microscopy before and after dissolution studies. Chemical analyses of elemental transfer to the solution were assessed to evaluate the surface stability of the new coating. An in vivo biocompatibility study for particulates [of boron (B), titanium alloy (Ti), cobalt alloy (Co), and combinations of B + Ti and B + Co] was performed using a rat air pouch model. The inflammatory reactions to particulates were evaluated histologically and histochemically. No physical alteration was seen in the discs after the dissolution studies, and the elemental transfer to the dissolution solution was minimal. The cytokines, tumor necrosis factor (TNFα), and histology results from these simulated debris showed similar and moderate level responses magnitudes for the boron and mixtures and the primary alloy particulates. The conclusion from this initial study was that assessments of the coated discs showed physical properties similar to control. Also results from the in vivo studies of simulated wear debris from boron coatings on titanium and cobalt alloys demonstrated biocompatibility profiles that were mild to moderate and similar to prior analyses of wear debris products in synovial pouch models. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Endothelial cell growth on silicon modified hydrogenated amorphous carbon thin films
Authors: Ogwu A. A. , Okpalugo T. I. T. , Ali N. , Maguire P. D. , McLaughlin J. A. D. 
Published: September 2007

AbstractThe biological response of human microvascular endothelial cells (HMEC‐1) seeded on Si‐DLC films and on control surfaces was evaluated in terms of initial cell enhancement, growth, and cytotoxicity. The microstructure of the films was characterised by Raman spectroscopy and X‐ray photoelectron spectroscopy. The effect of changes in microstructure, surface energy, surface electronic state, and electronic conduction, on the biological response of the films to endothelial cells was investigated. Endothelial cell adhesion and growth was found to be affected by changes in the microstructure of the films induced by silicon doping and thermal annealing. We observed a significant statistical difference in endothelial cell count between the as‐deposited DLC and Si‐DLC films using the one sample t‐test at a p‐value of 0.05. We also found a statistically significant difference between the adhesion of HMEC films on DLC and Si‐DLC films at various annealing temperatures using the one‐way ANOVA F statistic test at p < 0.05 and the post‐hoc Tukey test. One sample t‐test at p < 0.05 of MTT‐assay results showed the endothelial cells to be viable when seeded on DLC/Si‐DLC films. We suspect that the increased adhesion of endothelial cells induced by increasing the amount of silicon in the Si‐DLC films is associated with the development of a suitable surface energy due to silicon addition, which neither favored cell denaturing nor preferential water spreading before cellular attachment on the film surface. The presence of an external positively charged dipole on the Si‐DLC films confirmed by our Kelvin probe measurements is also expected to enhance the adhesion of endothelial cells that are well known to carry a negative charge. The Si‐DLC films investigated hold potential promise as coatings for haemocompatible artificial implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Plasmapheresis for hemolytic crisis and impending acute liver failure in Wilson disease
Authors: Asfaha Samuel , Almansori Mohammed , Qarni Uwais , Gutfreund Klaus S. 
Published: September 2007

AbstractWilsonian crisis is fatal unless copper removal is initiated early and liver transplantation is performed for patients that fulfill criteria for a poor outcome. We report a patient presenting with severe hemolysis and impending acute liver failure that made a rapid recovery with prompt initiation of plasmapheresis and chelation therapy. Rapid copper removal by plasmapheresis alleviated hemolysis and liver injury. A review of the literature was performed examining the use of plasmapheresis and albumin dialysis with continuous veno‐venous hemodialysis or molecular adsorbents and recirculating system. J. Clin. Apheresis, 2007. © 2007 Wiley‐Liss, Inc.