bluuebunny/crossref_metadata_2025_split huggingface dataset:
An advanced analytical model for high damping rubber bearings
Authors: Tsai C. S. , Chiang Tsu‐Cheng , Chen Bo‐Jen , Lin Shih‐Bin 
Published: June 2003

AbstractBase‐isolation technologies have been developed over the years in attempts to mitigate the effects of earthquakes on structures and potentially vulnerable contents in earthquake prone areas of the world. The high damping rubber bearing (HDRB) is a relatively recent and evolving technology of this kind. The isolator shifts the fundamental period of the base‐isolated structure to a value beyond the range of the plentiful energy‐containing periods of earthquake motions and supplies significant damping to dissipate energy caused by motions. Nevertheless, the highly non‐linear mechanical behaviour of the HDRB is so complex, especially at large strains, that it is difficult to model it analytically. In this paper, an extensive study of experimental tests for identifying the mechanical characteristics of the HDRB is presented. By modifying the Wen's model to include the rate‐dependent effects, an advanced analytical model in an incremental form for the HDRB is also proposed. A very good agreement between the analytical and experimental results has been obtained. It is illustrated that the proposed mathematical model can predict well the mechanical behaviour of HDRB bearings, even at large shear strain. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic analysis of structures using modified Lanczos co‐ordinates
Authors: Kim Byoung‐Wan , Jung Hyung‐Jo , Kim Woon‐Hak , Lee In‐Won 
Published: June 2003

AbstractAn efficient dynamic analysis method using the modified Lanczos co‐ordinates is presented. The proposed method is obtained by applying the modified Lanczos algorithm using Lanczos vectors that satisfy the stiffness‐orthonormality condition to the conventional Lanczos co‐ordinates method. The modified Lanczos co‐ordinates method is more efficient than the conventional method in the case of structures under multi‐input loads. The effectiveness of the modified Lanczos co‐ordinates method is verified by analysing a numerical example. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluating foundation mass, damping and stiffness by the least‐squares method
Authors: Ju S. H. 
Published: June 2003

AbstractThis paper discusses how to use the three‐dimensional (3D) time‐domain finite‐element method incorporating the least‐squares method to calculate the equivalent foundation mass, damping and stiffness matrices. Numerical simulations indicate that the accuracy of these equivalent matrices is acceptable when the applied harmonic force of 1+sine is used. Moreover, the accuracy of the least‐squares method using the 1+sine force is not sensitive to the first time step for inclusion of data. Since the finite‐element method can model problems flexibly, the equivalent mass, damping and stiffness matrices of very complicated soil profiles and foundations can be established without difficulty using this least‐squares method. Copyright © 2003 John Wiley & Sons, Ltd.
Dispersion analysis of the least‐squares finite‐element shallow‐water system
Authors: Le Roux D. Y. , Carey G. F. 
Published: June 2003

AbstractThe frequency or dispersion relation for the least‐squares mixed formulation of the shallow‐water equations is analysed. We consider the use of different approximation spaces corresponding to co‐located and staggered meshes, respectively. The study includes the effect of Coriolis, and the dispersion properties are compared analytically and graphically with those of the mixed Galerkin formulation. Numerical solutions of a test problem to simulate slow Rossby modes illustrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical wave tank based on a σ‐transformed finite element inviscid flow solver
Authors: Turnbull M. S. , Borthwick A. G. L. , Taylor R. Eatock 
Published: June 2003

AbstractInviscid two‐dimensional free surface wave motions are simulated using a σ‐transformed finite‐element model based on potential theory for irrotational, incompressible fluid flow over a flat fixed bed. The free surface boundary condition is fully non‐linear, and so non‐linear effects up to very high order can be modelled. The σ‐transformation involves linear stretching of the mesh between the bed and free surface. This has two major advantages. First, remeshing due to the moving free surface is avoided. Second, the mesh nodes are aligned vertically, allowing a high order calculation of the free surface vertical velocity component to be implemented without smoothing, except for very steep waves. The model however is further restricted to non‐overturning, non‐breaking waves because of the uniqueness of the σ‐transformation. Excellent agreement is obtained with analytical and alternative numerical data for small amplitude free sloshing in a rectangular tank and forced sloshing in a horizontally base‐excited rectangular tank. At higher amplitudes, non‐linear effects are evident in the simulations by the present numerical model. The model is also able to reproduce steep progressive waves due to a wave‐maker in agreement with Stokes 5th theory, second‐order shallow water waves in agreement with cnoidal theory, and focused wave groups that match the experimental measurements acquired by Baldocket al. [A laboratory study of non‐linear surface waves on water.Phil. Trans. R. Soc. Lond. A 1996;354:649–676]. Copyright © 2003 John Wiley & Sons, Ltd.
A time‐implicit high‐order compact differencing and filtering scheme for large‐eddy simulation
Authors: Rizzetta D. P. , Visbal M. R. , Blaisdell G. A. 
Published: June 2003

AbstractThis work investigates a high‐order numerical method which is suitable for performing large‐eddy simulations, particularly those containing wall‐bounded regions which are considered on stretched curvilinear meshes. Spatial derivatives are represented by a sixth‐order compact approximation that is used in conjunction with a tenth‐order non‐dispersive filter. The scheme employs a time‐implicit approximately factored finite‐difference algorithm, and applies Newton‐like subiterations to achieve second‐order temporal and sixth‐order spatial accuracy. Both the Smagorinsky and dynamic subgrid‐scale stress models are incorporated in the computations, and are used for comparison along with simulations where no model is employed. Details of the method are summarized, and a series of classic validating computations are performed. These include the decay of compressible isotropic turbulence, turbulent channel flow, and the subsonic flow past a circular cylinder. For each of these cases, it was found that the method was robust and provided an accurate means of describing the flowfield, based upon comparisons with previous existing numerical results and experimental data. Published in 2003 by John Wiley & Sons, Ltd.
Thermal properties of cowpea flour: A study by differential scanning calorimetry
Authors: Henshaw Folake O. , McWatters Kay H. , Akingbala John O. , Chinnan Manjeet S. 
Published: June 2003

AbstractThe thermal properties of 12 varieties of cowpea flour were studied by differential scanning calorimetry (DSC). Flour samples were prepared to a paste of 60% moisture content and sealed in standard DSC pans. Samples were scanned at a heating rate of 5°C/min over a scan range of 40–130°C. Samples exhibited single major endotherms, which occurred over varied temperatures. The transition enthalpy (ΔH) ranged between 1.4 J/g and 4.7 J/g. Transition onset (To) and transition peak (Tp) temperatures ranged between 75–78°C and 78–82°C, respectively. All the DSC parameters measured varied significantly among the varieties. The transition enthalpy (ΔH) was the most discriminating parameter and accounted for 80% of the total variance. The major chemical components of cowpea flour, starch amylose and protein are significant predictors of ΔH. Protein denaturation appears to be a significant modification which occurs during processing of cowpea seeds to flour. The transition enthalpy ΔH could become an important functional index of cowpea flour when related to some quality parameters in products that contain the flour.
Differentiation of toxigenic Staphylococcus aureusin staphylococcal isolates from prepared and frozen foods by combined arbitrarily primed polymerase chain reaction and DNA probe
Authors: Córdoba M. G. , Jordano R. , Aranda E. , Benito M. J. , Córdoba J. J. 
Published: June 2003

AbstractIn prepared and frozen flamenquín and hake fish fingers Staphylococcus aureus as sanitary hazards have been detected. In the present work, a combined method that includes an arbitrarily primed PCR (AP‐PCR) and a mixed DNA probe hybridisation designed for the enterotoxigenic genes sea, seb, sec, and sed will be assayed to differentiate enterotoxigenic S. aureus from other staphylococcal species isolated during the processing of prepared and frozen foods. From the protocols tested for the AP‐PCR, the highest number of amplification bands showing the best resolution was achieved at 30°C annealing and 35°C extension temperatures. Several staphylococci identified by a biochemical test as S. aureus showed in the AP‐PCR analysis different banding patterns to the references S. aureus. The isolates, were investigated by slot blot hybridisation for genes encoding A, B, C, and D staphylococcal enterotoxins to determine their enterotoxigenic potential. Several isolates characterised by the AP‐PCR analysis as S. aureus hybridised with the DNA probe mixture. The combined AP‐PCR and DNA probe hybridisation assayed was able to differentiate toxigenic S. aureus from other staphylococcal species from prepared and frozen foods. This method could be considered as microbial quality assurance in these products.
Mathematical modeling of Saccharomyces cerevisiae inactivation under high‐pressure carbon dioxide
Authors: Erkmen Osman 
Published: June 2003

AbstractHigh‐pressure carbon dioxide inactivation curves of Saccharomyces cerevisiae at different temperatures were analysed using the modified Gompertz model. Comparable λ and μ values were obtained under pressure treatment as function of temperature. The phase of disappearance (λ) and the inactivation rate (μ) of S. cerevisiae were inversely related. Higher μ values were obtained at 50°C than at 40, 30, and 20°C under 10.0 MPa CO2 pressure. Increased pressure and temperature had significant effects on the survival of S. cerevisiae. Arrhenius, linear and square‐root models were used to analyse the temperature dependence of the inactivation rate constant. For the Arrhenius model the activation energy (Eμ) was 56.49 kJ/mol at 10.0 MPa, and 55.70, 53.83, and 52.20 kJ/mol at 7.5, 5.0, and 2.5 MPa, respectively. Results of this study enable the prediction of yeast inactivation exposed to different CO2 pressures and temperatures.
Phenolic constituents and antioxidant capacities of Crataegus monogyna (Hawthorn) callus extracts
Authors: Bahorun Theeshan , Aumjaud Esha , Ramphul Hemlata , Rycha Maheshwaree , Luximon‐Ramma Amitabye , Trotin Francis , Aruoma Okezie I. 
Published: June 2003

AbstractCrataegus (Hawthorn) has long been used as a folk medicine and is widely utilized in pharmaceutical preparations mainly because of its neuro‐ and cardiosedative actions and its low toxicity. The pharmacological effects of Crataegus have mainly been attributed to the polyphenolic contents. In this study, the production of polyphenols by ten‐year‐old Crataegus monogyna calli was studied in relation to growth variation and antioxidant capacity within a subculture period. Assays based on the Trolox equivalent antioxidant capacity (TEAC( ferric reducing antioxidant power (FRAP) and stability in oil‐in‐water emulsion were used to characterize the antioxidant actions of the callus cultures. High TEAC (3.66 μmol/g dry weight) and FRAP (208.19 μmol Fe2+/g dry weight) values were observed when maximal growth was reached (days 30–35( and this seemed to be influenced by optimum total phenol (47.40 mg/g dry weight( proanthocyanidin (20.81 mg/g dry weight( flavonoid (7.01 mg/g dry weight( anthocyanin (6.18 mg/g dry weight( (–)‐epicatechin (1.77 mg/g dry weight( procyanidin B2 (3.97 mg/g dry weight( and chlorogenic acid (1.11 mg/g dry weight) production during that period. The TEAC values were strongly associated with total flavonoids and to a lesser extent with total phenols, anthocyanins and total proanthocyanidins. The FRAP antioxidant values correlated to total phenols, proanthocyanidins and flavonoids, respectively. The polyphenolic rich calli were as effective as butylated hydroxytoluene (BHT) in preventing hydroperoxide and conjugated diene formation in a 30% oil‐in‐water emulsion prepared with stripped sunflower oil, during 7 days storage at 30°C. Crataegus monogyna cell culture represents an important alternative source for natural antioxidants.
Characterisation and quantification of the reaction(s) catalysed by transglutaminase using the o‐phthaldialdehyde reagent
Authors: Flanagan John , FitzGerald Richard J. 
Published: June 2003

AbstractThe potential application of the o‐phthaldialdehyde (OPA) reagent for quantification of the type and extent of the reaction(s) catalysed by transglutaminase (TGase) during incubation with sodium caseinate (NaCN) was investigated. Initial studies were performed to ensure that NH3, a by‐product of TGase activity, could be determined with the OPA reagent in trichloroacetic acid (TCA) supernatants of NaCN solutions. The detectable concentration of exogenously added NH3 (at NH3 concentrations > 10 mM) was found to decrease during extended incubation at 23, 37 and 50°C and at either pH 7.0 or 8.0 in 4% w/v NaCN solutions, even when taking into account the evaporation of water from the sample. The recovery of NH3 from 12% w/v TCA supernatants of NaCN solutions spiked with 5 mM NH3 at 23°C and pH 7.0 was found to be 88%. The release of NH3 and the decrease in ε‐amino groups on incubating NaCN with TGase was subsequently quantified using the OPA reagent. Incubation of NaCN (4% w/v) with TGase at 23°C resulted in progressive increases and decreases, respectively, in NH3 and ε‐amino group concentration with increased incubation time. These changes were dependent on TGase : NaCN. It was estimated that approximately 20% of the available Lys residues in NaCN were involved in TGase‐catalysed cross‐links. However, the observed decrease in ε‐amino group concentration was higher than expected. This may be due to concealment of noncross‐linked amino groups in polymerised NaCN, making them unavailable for reaction with the OPA reagent.
The effect of water content on proton transport in polymer electrolyte membranes
Authors: Commer P. , Cherstvy A.G. , Spohr E. , Kornyshev A.A. 
Published: June 2003

AbstractWe investigate proton transport in a polymer electrolyte membrane using continuum theory and molecular dynamics (MD) computer simulations. Specifically our goal is to understand the possible molecular origin of the effect of water content on the activation energy (AE) and pre‐exponential factor of proton conductivity, in comparison with experimental observations reported for Nafion, where a decrease of AE with increasing water content has been observed. We study proton diffusion in a single pore, using a slab‐like model. We find that although the average proton diffusion coefficient is several times smaller in a narrow pore than in a wide water‐rich pore, its AE is almost unaffected by the pore width. This contradicts an earlier proposed conjecture that the sizable Coulomb potential energy barriers near the lattice of immobile point‐like SO3– groups increase the AE in a narrow pore. Here we show that these barriers become smeared out by thermal motion of SO3– groups and by the spatial charge distribution over their atoms. This effect strongly diminishes the variation of the AE with pore width, which is also found in MD simulations. The pre‐exponential factor for the diffusion process, however, decreases, indicating a limited number of pathways for proton transfer and the freezing out of degrees of freedom that contribute to the effective frequency of transfer. Decreasing the pore size diminishes bulk‐like water regions in the pore, with only less mobile surface water molecules remaining. This hampers proton transfer. The increase of AE takes place only if the thermal motion of the SO3– head groups freezes out simultaneously with decreasing water content, but the effect is not profound. The stronger effect observed experimentally may thus be associated with some other rate‐determining consecutive process, concerned with polymer dynamics, such as opening and closing of connections (bridges) between aqueous domains in the membrane under low water content.
Radioactive Labeling Study and FTIR Measurements of Methanol Adsorption and Oxidation on Fuel Cell Catalysts
Authors: Coutanceau C. , Hahn F. , Waszczuk P. , Wieckowski A. , Lamy C. , Léger J.‐M. 
Published: June 2003

AbstractThe adsorption and the electrooxidation of methanol‐derived surface CO on fuel‐cell grade platinum and platinum‐ruthenium alloy nanoparticle catalysts were studied using a combination of electrochemical measurements and radioactive labeling (thin foil radioactive labeling technique) and in situ infrared reflectance spectroscopy. The kinetics of formation of surface and bulk products coming from methanol and surface/bulk exchange processes were found to be significantly different on Pt compared to Pt/Ru. The observed difference in the kinetics of CO adsorption underlines the electronic effect in the surface catalytic activity due to modification of the electronic structure of surface platinum atoms by ruthenium. Correlation between FTIR and radiolabeling measurements indicated that the adsorption of CO from methanol is a very slow process at low potential but that the coverage by CO poison is greater at higher potential. Then, the results obtained from both analytical techniques (in situ IR reflectance spectroscopy and radioactive labeling method) displayed very good agreement and allowed us to validate them for the investigation of the methanol oxidation mechanism.
Performance of a DMFC Using Pt‐Ru/C Catalysts Prepared by Reduction with Formic Acid
Authors: Lizcano‐Valbuena W.H. , de Souza A. , Paganin V.A. , Leite C.A.P. , Galembeck F. , Gonzalez E.R. 
Published: June 2003

AbstractIn this work Pt‐Ru/C catalysts are prepared in different atomic ratios by reduction with formic acid and submitted to thermal treatment in a hydrogen atmosphere. Physical characterisation of the materials by XRD, EDX, and TEM shows that the particle size increases as a consequence of the thermal treatments and this effect is relevant in the electrochemical behaviour of these materials in a DMFC. Finally, the performance of the DMFC with different flow fields is examined.
Dynamic Modeling and Simulation of a Countercurrent Molten Carbonate Fuel Cell (MCFC) with Internal Reforming
Authors: Heidebrecht P. , Sundmacher K. 
Published: June 2003

AbstractA dynamic mathematical model for a countercurrent MCFC with direct internal methane reforming is introduced. It allows for the simulation of the gas phase compositions and flows, the temperatures in gas and solid phases, the cell voltage, and the current density distribution. This state space model is fully formulated in terms of dimensionless parameter groups, which are derived from the underlying physical and chemical phenomena. The model assumptions and equations are outlined in detail and a numerical solution strategy is proposed. The model is used to predict the current‐voltage curve as well as the dynamic cell response to a stepwise load change.
Genomic imbalances in CML blast crisis: 8q24.12–q24.13 Segment identified as a common region of over‐representation
Authors: Gribble Susan M. , Reid Alistair G. , Roberts Ian , Grace Colin , Green Anthony R. , Nacheva Elizabeth P. 
Published: June 2003

AbstractThe acute phase of chronic myeloid leukemia (CML) is accompanied by secondary chromosomal changes. The additional changes have a non‐random pattern; however, highly abnormal (marker) chromosomes are reported in some 20% of abnormal karyotypes. These marker chromosomes have proved to be beyond the resolution of conventional G‐banding analysis. We used molecular cytogenetic techniques to determine the structure of complex chromosome markers in 10 CML‐derived cell lines after our investigations of CML patients in blast crisis. Multicolor fluorescence in situ hybridization identified a multitude of structural chromosome aberrations. In addition, genomic gains identified by comparative genomic hybridization (CGH) were mapped to highly complex marker chromosomes in more than one cell line. The most common genomic loss detected by CGH affected chromosome 9, whereas the most common genomic gains affected, in order of frequency, the sequences of 8q, 6, and 13q. The smallest discrete amplification on 8q was identified in cell line MEG‐01. This amplicon contains sequences represented by the marker D8S263/RMC08P029 but did not contain the proximal MYC gene or a more distal marker, D8S256/RMC08P025. We determined the size of the amplicon to be less than the chromosome segment 8q24.12–q24.13. The use of region‐ and locus‐specific probes to analyze the organization of highly complex marker structures aided the identification of preferentially amplified genomic regions. The resultant amplifications could harbor gene(s) driving disease progression. © 2003 Wiley‐Liss, Inc.
Molecular characterization of acute leukemias by use of microarray technology
Authors: Kohlmann Alexander , Schoch Claudia , Schnittger Susanne , Dugas Martin , Hiddemann Wolfgang , Kern Wolfgang , Haferlach Torsten 
Published: June 2003

AbstractAccurate subclassification of leukemia and the identification of prognostic determinants are essential to guide therapy and to improve patients' outcome. According to present standards, pre‐therapeutic assessment depends on a combination of different methods. We aimed to expand the molecular characterization of different acute leukemia subtypes to identify new genome‐wide diagnostic markers. Total RNA from 90 adult patients suffering from acute lymphoblastic leukemia (ALL, n = 25) and acute myeloid leukemia (AML, n = 65) was extracted at diagnosis and high density oligonucleotide microarrays were used to analyze the expression profiles of 12,000/22,000 genes in all specimens (Affymetrix U95Av2/U133A). All cases were thoroughly characterized by individual combinations of cytomorphology, cytogenetics, multiparameter immunophenotyping, and molecular genetics. The expression signature of a small set of differentially expressed genes was sufficient to accurately discriminate eight clinically relevant acute leukemia subgroups. Underlying chromosomal aberrations or immunophenotypical characteristics were strictly correlated with a distinct gene expression pattern for AML with t(8;21), t(15;17), t(11q23)/MLL, or inv(16) as well as for precursor B‐ALL with t(9;22), t(8;14), or t(11q23)/MLL and precursor T‐ALL. These data support a possible future application of microarray technology for classification of the acute leukemias. © 2003 Wiley‐Liss, Inc.