bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genotoxicity, cytotoxicity, and reactive oxygen species induced by single‐walled carbon nanotubes and C60 fullerenes in the FE1‐Muta™Mouse lung epithelial cells
Authors: Jacobsen Nicklas Raun , Pojana Giulio , White Paul , Møller Peter , Cohn Corey Alexander , Smith Korsholm Karen , Vogel Ulla , Marcomini Antonio , Loft Steffen , Wallin Håkan 
Published: July 2008

AbstractViability, cell cycle effects, genotoxicity, reactive oxygen species production, and mutagenicity of C60 fullerenes (C60) and single‐walled carbon nanotubes (SWCNT) were assessed in the FE1‐Muta™Mouse lung epithelial cell line. None of these particles induced cell death within 24 hr at doses between 0 and 200 μg/ml or during long‐term subculture exposure (576 hr) at 100 μg/ml, as determined by two different assays. However, cell proliferation was slower with SWCNT exposure and a larger fraction of the cells were in the G1 phase. Exposure to carbon black resulted in the greatest reactive oxygen species generation followed by SWCNT and C60 in both cellular and cell‐free particle suspensions. C60 and SWCNT did not increase the level of strand breaks, but significantly increased the level of FPG sensitive sites/oxidized purines (22 and 56%, respectively) determined by the comet assay. The mutant frequency in the cII gene was unaffected by 576 hr of exposure to either 100 μg/ml C60 or SWCNT when compared with control incubations, whereas we have previously reported that carbon black and diesel exhaust particles induce mutations using an identical exposure scenario. These results indicate that SWCNT and C60 are less genotoxic in vitro than carbon black and diesel exhaust particles. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.
Effects of low dose radiation and vitamin C treatment on chloroquine‐induced genotoxicity in mice
Authors: Roy Lopamudra Das , Mazumdar Mehnaz , Giri Sarbani 
Published: July 2008

AbstractChloroquine (CHQ) is a commonly used antimalarial agent. We evaluated the genotoxic potential of CHQ using chromosome aberration (CA), micronucleus (MN), and sperm head abnormality (SA) assays in vivo in Swiss albino mice. The interaction between a low dose of radiation and CHQ, as well as the effect of vitamin C on CHQ‐induced genotoxicity, was also evaluated. It was observed that CHQ induced CA, as well as MN, in the bone marrow cells under certain treatment conditions. Further, CHQ induced significant increase in the frequency of SA both at 24 hr and 21 days of the treatment. In the present study vitamin C pretreatment apparently reduced the frequency of CA, MN, and SA induced by CHQ. In the combination studies with radiation and CHQ, we found that exposure to low doses of radiation (0.5 Gy) either prior to or following CHQ treatment, in the dose ranges tested, has little or no synergistic effect in the mutagenic evaluations in somatic cells. However, radiation exposure along with CHQ treatment resulted in significant increase in the frequency of SA as compared to the groups receiving CHQ alone at 21 days of the treatment. In summary, CHQ has the potential to induce genotoxicity in mammalian cells. Further, germ cells may be relatively more sensitive as compared to the somatic cells. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.
Dynamic systems with high damping rubber: Nonlinear behaviour and linear approximation
Authors: Dall'Asta Andrea , Ragni Laura 
Published: July 2008

AbstractHigh damping rubber (HDR) shows a quite complex constitutive behaviour, which is nonlinear with respect to strain and is dependent on the strain rate. In addition, it exhibits a transient response during which the material properties change (scragging or more generally the Mullins effect). A number of recent works were dedicated to analysing and modelling material behaviour. This paper studies the nonlinear dynamics of systems with restoring force produced by HDR‐based devices in order to propose a procedure to define equivalent linear models considering both transient and stationary behaviours. The reliability of these linear models is tested by evaluating the upper and lower bounds of the seismic response of a structural system equipped with HDR‐based devices (structural system with dissipative bracings and isolated systems). Copyright © 2008 John Wiley & Sons, Ltd.
Modelling exterior beam–column joints for seismic analysis of RC frame structures
Authors: Favvata Maria J. , Izzuddin Bassam A. , Karayannis Chris G. 
Published: July 2008

AbstractIn common practice, the local response of beam–column joints is not considered for the seismic analysis of multistorey reinforced concrete (RC) frame structures, where these critical regions are typically assumed as rigid. Studies that incorporate the local effect of the joints in the seismic analysis of multistorey RC frame structures are limited. Identifying the main disadvantages of the analytical models that have been proposed so far, a behavioural model is developed for the simulation of the local inelastic response of exterior RC beam–column joints in multistorey RC frame structure. Special attention is given to the description of the main characteristics of the actual seismic response of the joints, including strength and stiffness degradation. The proposed model is incorporated as a rotational spring element in a general program for nonlinear static and dynamic analysis of structures, and a procedure for the evaluation of the required model parameters is also presented. The effectiveness of the proposed joint element model is demonstrated through comparisons with experimental data of 12 RC exterior joints reported in the literature. Moreover, using the proposed element, the influence of the local nonlinear response of RC exterior beam–column joints on the ductility requirements of columns and on the failure mode and overall seismic response of a multistorey RC frame structure is investigated. From the results of these analyses, it is concluded that the modelling of exterior RC joints with reduced capacity as rigid joints can lead to unconservative results and therefore to unsafe design. Copyright © 2008 John Wiley & Sons, Ltd.
A stochastic ground motion model with separable temporal and spectral nonstationarities
Authors: Rezaeian Sanaz , Der Kiureghian Armen 
Published: July 2008

AbstractA fully nonstationary stochastic model for strong earthquake ground motion is developed. The model employs filtering of a discretized white‐noise process. Nonstationarity is achieved by modulating the intensity and varying the filter properties in time. The formulation has the important advantage of separating the temporal and spectral nonstationary characteristics of the process, thereby allowing flexibility and ease in modeling and parameter estimation. The model is fitted to target ground motions by matching a set of statistical characteristics, including the mean‐square intensity, the cumulative mean number of zero‐level up‐crossings and a measure of the bandwidth, all expressed as functions of time. Post‐processing by a second filter assures zero residual velocity and displacement, and improves the match to response spectral ordinates for long periods. Copyright © 2008 John Wiley & Sons, Ltd.
Numerical simulation of reinforcement strengthening for high‐arch dams to resist strong earthquakes
Authors: Long Yuchuan , Zhang Chuhan , Jin Feng 
Published: July 2008

AbstractThis paper focuses on analyzing the nonlinear seismic response of high‐arch dams with cantilever reinforcement strengthening. A modified embedded‐steel model is presented to evaluate the effects of the strengthening measure on alleviating the extension and opening of cracks under strong earthquakes. By stiffening reinforced steel, this model can easily consider the steel–concrete interaction for lightly reinforced concrete (RC) members without the need of dividing them into RC and plain concrete zones. The new tensile constitutive relations of reinforced steel are derived from the load–deformation relationship of RC members in direct tension. This model has been implemented in the finite element code and its applicability is verified by two numerical simulations for RC tests. Subsequently, numerical analyses for a 210‐m high‐arch dam (Dagangshan arch dam) are conducted with and without the presence of cantilever reinforcement. Numerical results show that reinforcement strengthening can reduce the nonlinear response of the arch dam, e.g. joint opening and crest displacement, and limit the extension and opening width of concrete cracks. Copyright © 2008 John Wiley & Sons, Ltd.
Personal standards, self‐evaluation and perceived benefits of thinness in girls and young women with disturbed eating
Authors: Aila Gustafsson Sanna , Edlund Birgitta , Kjellin Lars , Norring Claes 
Published: July 2008

AbstractThe aim of this study was to examine personal standards, self‐evaluation and perceived benefits of thinness in Swedish females 14–21 years with disturbed eating (DE) and to compare these to a group with other psychosocial problems and to a symptom free group. Seventy subjects with DE‐group, 65 subjects with psychosocial problems and 70 symptom free subjects were compared regarding items selected from four questionnaires. High personal standards expressed in a competitive way were specific for the DE‐group. In comparison with the other groups the DE‐group also reported significantly more perceived benefits of thinness and they more frequently believed that thinness would make them more popular. The DE‐group also reported a more negative self‐evaluation, although this was a trait shared with the subjects with other psychosocial problems and consequently not specific for the DE‐group. Identifying specific factors that perpetuate DE habits is important in order to improve our understanding and enhance the treatment of eating disorders. Copyright © 2008 John Wiley & Sons, Ltd and Eating Disorders Association.
A numerical study of heat island flows: Stationary solutions
Authors: Dubois Thierry , Touzani Rachid 
Published: July 2008

AbstractWe present two‐dimensional numerical simulations of a natural convection problem in an unbounded domain. The flow circulation is induced by a heat island located on the ground and thermal stratification is applied in the vertical direction. The main effect of this stably stratified environment is to induce the propagation of thermal perturbations in the horizontal direction far from the local thermal source. Numerical stationary solutions at Ra⩽105 are computed in large elongated computational domains: convergence with respect to the domain sizes is investigated at different resolutions. On fine grids, with mesh size ${h} = {{1} \over {128}}$, a thermal sponge layer is added at the vertical boundaries: this local damping technique improves the convergence with respect to the domain length. Boussinesq equations are discretized with a second‐order finite volume scheme on a staggered grid combined with a second‐order projection method for the time integration. Copyright © 2008 John Wiley & Sons, Ltd.
Galerkin technique based on beam functions in application to the parametric instability of thermal convection in a vertical slot
Authors: Papanicolaou N. C. , Christov C. I. , Homsy G. M. 
Published: July 2008

AbstractA Fourier–Galerkin spectral technique for solving coupled higher‐order initial‐boundary value problems is developed. Conjugated systems arising in thermoconvection that involve both equations of fourth and second spatial orders are considered. The set of so‐called beam functions is used as basis together with the harmonic functions. The necessary formulas for expressing each basis system into series with respect to the other are derived.The convergence rate of the spectral solution series is thoroughly investigated and shown to be fifth‐order algebraic for both linear and nonlinear problems. Though algebraic, the fifth‐order rate of convergence is fully adequate for the generic problems under consideration, which makes the new technique a useful tool in numerical approaches to convective problems.An algorithm is created for the implementation of the method and the results are thoroughly tested and verified on different model examples. The spatial and temporal approximation of the scheme is tested. To further validate the scheme, a singular asymptotic expansion is derived for small values of the modulation frequency and amplitude and the numerical and analytic results are found to be in good agreement.The new technique is applied to the G‐jitter flow, and the Floquet stability diagrams are produced. We obtain the expected alternating isochronous and subharmonic branches and find that stable motions are always isochronous while unstable motions can be either isochronous or subharmonic. The numerical investigation also leads to novel conclusions regarding the dependence of the amplitude of the solutions on some of the governing parameters. Copyright © 2008 John Wiley & Sons, Ltd.
14th International Conference on Finite Elements in Flow Problems
Authors: Christon Mark A. , Coutinho Alvaro L. G. A. 
Published: July 2008

AbstractThis special issue is dedicated to the Fourteenth Finite Elements in Flow Problems Conference held in Santa Fe, New Mexico, on March 24–28, 2007. The papers in this special issue were selected to represent the broad cross‐section of computational fluid dynamics topics ranging from discontinuous Galerkin and stabilized methods to fluid–structure interaction and viscoelastic flows at the 14th meeting. Copyright © 2008 John Wiley & Sons, Ltd.
In allen Zungen
Authors: Finetti Marco 
Published: July 2008

AbstractWissenschaft lebt auch von der Vielfalt der Sprachen. Angesichts der Dominanz des Englischen setzt sich die DFG für eine Kultur der Mehrsprachigkeit ein. Gerade in den Geistes‐ und Sozialwissenschaften soll dabei das Deutsche seinen festen Platz haben
Mit Mathematik unters Messer
Authors: Deuflhard Peter 
Published: July 2008

AbstractEin Gesicht kann durch Geburt oder Unfall entstellt sein. Die Mund‐Kiefer‐Gesichts‐Chirurgie versucht, vieles zu korrigieren. Bei der Planung der Operationen helfen hochkomplexe Differentialgleichungen und dreidimensionale Visualisierungen
Fjellbirke, Waldgrenze und Klimawandel
Authors: Holtmeier Friedrich‐Karl , Anschlag Kerstin , Broll Gabriele , Brauckmann Hans‐Jörg 
Published: July 2008

AbstractÜberraschende Nachrichten aus Finnisch‐Lappland: Seit 30 Jahren untersuchen Landschaftsökologen die Birkenwälder im Norden Europas. Sie reagieren langsamer als erwartet auf die sich ständig verändernden Standort‐ und Lebensbedingungen
Kosmische Eindringlinge unter Beobachtung
Authors: Keilhauer Bianca , Blümer Johannes 
Published: July 2008

AbstractAtomkerne, Photonen und Neutrinos regnen unablässig aus dem Weltraum auf die Erde herab. Am Pierre Auger‐Observatorium in Argentinien blicken Forscher mit bisher unerreichter Präzision auf die höchstenergetischen Teilchen – und erhoffen sich dadurch neues Wissen über unser Universum
Influence of Methanol Crossover on the Fuel Utilization of Passive Direct Methanol Fuel Cell
Authors: Lai Q.‐Z. , Yin G.‐P. , Wang Z.‐B. , Du C.‐Y. , Zuo P.‐J. , Cheng X.‐Q. 
Published: July 2008

AbstractThe effect of methanol crossover on the fuel utilization of a passive direct methanol fuel cell (DMFC) was reported. The results revealed that the Faradaic efficiency decreased from 46.9 to 17.4% when methanol concentration increased from 1.0 to 8.0 mol L–1 at the lower current density 11.1 mA cm–2. However, the Faradaic efficiency increased from 14.7 to 31.3% when methanol concentration increased from 1.0 to 8.0 mol L–1 at a higher current density of 44.4 mA cm–2. On the other hand, although the amount of methanol was increased, the Faradaic efficiency did not change, obviously due to the uniform methanol crossover and methanol diffusion at the same methanol concentration and constant current.
Modelling of Proton Diffusion in Immobilised Imidazole Systems for Application in Fuel Cells
Authors: Tölle P. , Cavalcanti W. L. , Hoffmann M. , Köhler C. , Frauenheim T. 
Published: July 2008

AbstractThe mobility of an excess proton has been studied in systems of immobilised imidazole under different conditions using quantum mechanical approaches coupled to a molecular mechanics force field in molecular dynamics. The system is a simple model for imidazole covalently bound to a mesoporous material. Such materials are intended to be used as an additive to a polymer electrolyte membrane for fuel cells. This theoretical work is focused on dynamic properties of the proton transport. The diffusion constant of the system is found to be in the order of magnitude of 10–9 m2 s–1 and it is verified that the proton diffusion increases with increase in temperature or density. Further, the proton transport mechanism is investigated.
Partially Fluorinated Aarylene Polyethers and their Ternary Blends with PBI and H3PO4. Part II. Characterisation and Fuel Cell Tests of the Ternary Membranes
Authors: Li Q. , Jensen J. O. , Pan C. , Bandur V. , Nilsson M. S. , Schönberger F. , Chromik A. , Hein M. , Häring T. , Kerres J. , Bjerrum N. J. 
Published: July 2008

AbstractTernary blend membranes based on sulphonated partially fluorinated arylene polyether, polybenzimidazole (PBI) and phosphoric acid were prepared and characterised as electrolyte for high temperature proton exchange membrane fuel cells. Partially fluorinated arylene polyether was first prepared from polycondensation of decafluorobiphenyl with 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane, followed by sulphonation with H2SO4/60% SO3, based on which binary blends with PBI were prepared and further doped with concentrated phosphoric acid at temperatures of up to 130 °C. Acid doping levels as high as 10–13 mol phosphoric acid per PBI repeat unit can be reached, showing small swelling and excellent mechanical strength. At an acid doping level of 11, a conductivity of 0.12 S cm–1 was obtained at 175 °C and 10% relative humidity. Such a membrane exhibits a tensile strength of 6 MPa, elongation of 220% and modulus of 50 MPa at 150 °C. Based on these ternary membranes large MEAs with an active area of 256 cm2 have been prepared for a 2 kWel stack showing good performance and reproducibility.
Phosphotungstic Acid Supported on a Nanopowdered ZrO2 as a Filler in Nafion‐Based Membranes for Polymer Electrolyte Fuel Cells
Authors: Saccà A. , Carbone A. , Pedicini R. , Marrony M. , Barrera R. , Elomaa M. , Passalacqua E. 
Published: July 2008

AbstractAn inorganic filler prepared by impregnation of phosphotungstic heteropolyacid on zirconia (HPW/Zr) was developed to be inserted into a perfluorosulphonic polymer matrix for a polymer electrolyte fuel cell (PEFC) operating at a medium temperature (80–120 °C) and low relative humidity (RH). Two different phosphotungstic acid (PWA) loadings (30 and 45% w/w) were anchored on a nanopowdered ZrO2. Such compounds were characterised by different techniques: differential scanning calorimetry (DSC), X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDX) and porosity and surface area by Brunauer–Emmett–Teller (BET), to verify the introduction and anchorage of PWA on ZrO2. Two composite Nafion membranes were prepared and characterised in terms of chemical–physical characteristics and electrochemical tests. Thermogravimetric analysis (TGA) provided evidence that HPW/Zr had been incorporated into composite membranes and it was not eluted. A good proton conductivity of about 6 × 10–3 S cm–1 at 120 °C and 25% RH was recorded.Accelerated in situ ageing tests highlighted a good electrochemical stability (more than 150 cycles at 90 °C with dry gases) of the composite membranes with a slow decay and a reasonable integrity of the analysed membrane‐electrodes assembly (MEA). Finally, a post‐mortem SEM–EDX analysis on MEAs confirmed the presence of HPW/Zr in the membrane after the in situ testing.
Partially Fluorinated Arylene Polyethers and Their Ternary Blend Membranes with PBI and H3PO4. Part I. Synthesis and Characterisation of Polymers and Binary Blend Membranes
Authors: Kerres J. , Schönberger F. , Chromik A. , Häring T. , Li Q. , Jensen J. O. , Pan C. , Noyé P. , Bjerrum N. J. 
Published: July 2008

AbstractA partially fluorinated polyether ionomer from polycondensation of decafluorobiphenyl with 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane, followed by sulphonation with H2SO4 (60% SO3), has been prepared and optimised in terms of molecular weight and sulphonation degree. The partially fluorinated ionomer has been blended with poly(2,2′‐m‐phenylene‐5,5′‐bibenzimidazole) (PBI), yielding base–acid blends with PBI in excess. The base–acid blend membranes have been characterised in terms of solubility in DMAc, water uptake and oxidative stability by immersion in aqueous 5 wt.‐% H2O2 solutions and Fenton's Reagent, respectively.
Electrophoretic Deposition of Dense Sr‐ and Mg‐Doped LaGaO3 Electrolyte Films on Porous La‐Doped Ceria for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Bozza F. , Polini R. , Traversa E. 
Published: July 2008

AbstractThe application of the electrophoretic deposition (EPD) technique to the preparation of dense La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT‐SOFCs) was investigated. Suspensions of LSGM were prepared in acetone + I2 + H2O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape‐cast composite electrodes, composed of lanthanum‐doped ceria (La0.4Ce0.6O2 –x, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack‐free 15 μm thick LSGM films were obtained on porous LDC by co‐firing in air at 1,490 °C. Line profile analyses performed by energy dispersive X‐ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi‐layer co‐firing at 1,490 °C. EPD has thus proven to be a viable way for manufacturing anode‐supported LSGM electrolyte films.
Durability Studies of PBI‐based High Temperature PEMFCs
Authors: Yu S. , Xiao L. , Benicewicz B. C. 
Published: July 2008

AbstractLong‐term durability testing of polybenzimidazole (PBI)‐based polymer electrolyte membrane (PEM) fuel cells was performed using test protocols designed to simulate fuel cell operational situations which may be found in real applications. The fuel cell voltages and phosphoric acid (PA) loss were carefully monitored over thousands of hours and hundreds of cycles. In the typical operating range for high temperature PEM fuel cells (160 °C), the fuel cell voltage degradation rate was 4.9 μV h–1 for steady‐state operation. The PA loss rates were generally low and indicated that long‐term operation (>10,000 h) was possible without significant performance degradation due to PA loss from the membrane. Dynamic durability tests also showed that the PA loss rate from the membrane electrode assemblies (MEAs) depended on cell operating temperature and load conditions. Under all conditions, the PA loss was a relatively small amount of the total PA in the membrane.