bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Diastereoselective Synthesis of Chimeras of Proline and Glutamate.
Authors: Kudryavtsev Konstantin V. , Tsentalovich Mikhail Yu. , Yegorov Anton S. , Kolychev Eugene L. 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Total Synthesis of (.+‐.)‐2‐epi‐Validamine.
Authors: Okamura Hiroaki , Nagaike Hiroshi , Kipassa Nsiama Tienabe , Iwagawa Tetsuo , Nakatani Munehiro 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Arabidopside F, a New Oxylipin from Arabidopsis thaliana.
Authors: Nakajyo Haruyuki , Hisamatsu Yosuke , Sekiguchi Mitsuhiro , Goto Nobuharu , Hasegawa Koji , Shigemori Hideyuki 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Uncommon 5‐Methoxyisoflavans from Desmodium canum.
Authors: de Andrade Lima Claudia Sampaio , Zappia Giovanni , Delle Monache Giuliano , Botta Bruno 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Total Synthesis of (+)‐Rishirilide B: Development and Application of General Processes for Enantioselective Oxidative Dearomatization of Resorcinol Derivatives.
Authors: Mejorado Lupe H. , Pettus Thomas R. R. 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Towards Large Scale Production of CNF for Catalytic Applications
Authors: Kvande I. , Yu Z. , Zhao T. , Ronning M. , Holmen A. , Chen D. 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structures and Oxide Mobility in Bi—Ln—O Materials: Heritage of Bi2O3
Authors: Drache Michel , Roussel Pascal , Wignacourt Jean‐Pierre 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Total Synthesis of Spiroketal Containing Natural Products: Kinetic versus Thermodynamic Approaches
Authors: El Sous Mariana , Ganame Danny , Zanatta Shannon , Rizzacasa Mark A. 
Published: April 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Homology Modeling of the Serotonin Transporter: Insights into the Primary Escitalopram‐binding Site
Authors: Jørgensen Anne Marie , Tagmose Lena , Jørgensen Anne Marie M. , Topiol Sid , Sabio Michael , Gundertofte Klaus , Bøgesø Klaus P. , Peters Günther H. 
Published: April 2007

AbstractThe serotonin transporter (SERT) is one of the neurotransmitter transporters that plays a critical role in the regulation of endogenous amine concentrations and therefore is an important target for therapeutic agents affecting the central nervous system. The recently published, high resolution X‐ray structure of the closely related amino acid transporter,Aquifex aeolicusleucine transporter (LeuT), provides an opportunity to develop a three‐dimensional model of the structure of SERT. We present herein a homology model of SERT using LeuT as the template and containing escitalopram as a bound ligand. Our model explains selectivities known from mutational studies and varying ligand data, which are discussed and illustrated in the paper.
New Fused Triazinium Systems from (Alkoxycarbonyl)azinium N‐Aminides
Authors: Valenciano Jesús , Sánchez‐Pavón Esmeralda , Cuadro Ana M. , Alvarez‐Builla Julio , Vaquero Juan J. 
Published: March 2007

Abstract2‐(Alkoxycarbonyl)cycloimmonium N‐aminides are efficient 1,4‐dipoles that react with different types of reagents such as carbodiimides, benzoyliso(thio)cyanates and heterocyclicimidoyl chlorides to give new heterobetaines containing fused [1,2,4]triazinium systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Photoautotrophic Cell and Tissue Culture in a Tubular Photobioreactor
Authors: Perner‐Nochta I. , Lucumi A. , Posten C. 
Published: March 2007

AbstractAn externally illuminated tubular photobioreactor was constructed from 3.4 m stainless steel tubes and 22.1 m glass tubes for the cultivation of photoautotrophic organisms. The 30‐L reactor can be equipped with helical static mixers in order to create a uniform radial exchange within the tubes, 40 mm in diameter. A flexible construction of the reactor allows scale‐down experiments to be carried out with axial velocities between 0.3–2.5 m/s, gassing‐in rates of 0–0.5 L/min, kL a values of 0.002–0.006 s–1 and six metal halide lamps inducing photon flux densities in the range of 70–300 μE/m2s. Two model organisms, the green microalgae Chlorella vulgaris and the bryophyte Physcomitrella patens, were chosen to characterize cell growth and physiology in submerse cultures. Comparative experiments with Chlorella vulgaris in two configurations of the reactor with inserted helical static mixers and plates resulted in maximum growth rates of 1.6 d–1. No growth enhancement was obtained in the case of helical static mixers at a mean PFD of 150 μE/m2s and an axial velocity of 0.4 m/s. No homogenous flow could be obtained in the case of inserted plates. Physcomitrella patens was successfully cultivated in the reactor (μ = 0.36 d–1), whereas average axial velocities of ca. 0.6 m/s guarantee favorable gas transport without contributing to cell damage. This makes tubular photobioreactors a promising production system for the production of glycosylated recombinant proteins derived from moss.
Rotation effects on measurements of lateral motion
Authors: Rainer J. H. 
Published: March 2007

AbstractInertial transducers that measure horizontal movement are affected by rotation of the measurement location. In this paper, the effect of rotation is expressed quantitatively as a fraction of the translational signal amplitude and is shown to depend inversely on the effective radius of rotation of the measurement location and the square of the frequency component of the signal.Correction procedures are presented for various cases that arise in the determination of modal amplitudes and mode shapes for tower structures, suspension bridges and frame building structures. Specific numerical results are included for the CN Tower and the Commerce Court Building in Toronto, Canada, and the Lions' Gate Suspension Bridge in Vancouver, British Columbia. Rotational effects on signals obtained from horizontal transducers can be significant for very low frequency tower structures and suspension bridges, but are not likely to be of importance for frame buildings.
The effect of axial inertia on the bending eigenfrequencies of a timoshenko two‐bar frame
Authors: Kounadis A. N. , Sophianopoulos D. 
Published: March 2007

AbstractThe equations of free lateral vibrations of a uniform Timoshenko two‐bar frame including the effects of axial motion and joint mass with its rotational inertia are presented. The influence on the flexural eigenfrequencies of the axial motion alone or in combination with other parameters is fully assessed and thoroughly discussed. These parameters are: the translational and rotational inertia of the joint mass, the transverse shear deformation and rotatory inertia, the length, stiffness and slenderness ratios of the two bars of the frame.The variety of numerical results presented herein leads to the important finding that for framed structures the effect of axial inertia on the flexural eigenfrequencies alone or in combination with the foregoing parameters may be considerable. In particular, if the joint mass should be accounted for, the foregoing effect cannot be ignored, since it leads, in general, to considerable errors even for frames with relatively slender bars.
Rotational components of the surface ground motion during an earthquake
Authors: Castellani A. , Boffi G. 
Published: March 2007

AbstractUnder the assumption of an immovable point source for the earthquake energy release, a mathematical model is developed to compute the components of the free field surface rotation consistent with assigned translational components.Experimental evidence on these quantities is offered by the strong‐motion instrument arrays. However, lack of adequate identification of the different wave contributions prevents in general a direct measurement of rotational and torsional components, allowing only a qualitative assessment of just how large these components might be. The only exceptions are the records of SMART‐1, which offer the entire information to derive rotations.The available data of strong‐motion instrument arrays for this problem are summarized in Table I. They are in qualitative agreement with the suggestions of the mathematical model.Earthquake response spectra for the rotational components are developed for a few selected cases, in particular a rotational spectrum consistent with the prescription of USNRC Regulatory Guide 1.60.The correlations between the translational and rotational components of the ground motion are also shown.
Frequency response functions for arch dams: Hydrodynamic and foundation flexibility effects
Authors: Fok Ka‐Lun , Chopra Anil K. 
Published: March 2007

AbstractThe linear response of a selected arch dam to harmonic upstream, cross‐stream or vertical ground motion is presented for a wide range of the important system parameters characterizing the properties of the dam, impounded water, reservoir boundary materials and foundation rock. Based on these frequency response functions, the hydrodynamic and foundation flexibility effects in the dynamic response of arch dams are investigated.
On the dynamic response of rigid body assemblies
Authors: Allen R. H. , Oppenheim I. J. , Parker A. R. , Bielak J. 
Published: March 2007

AbstractThis paper examines dynamic response of a type of structural system that exhibits a significant degree of rigid body motion during earthquakes. An assembly of two‐dimensional rigid prisms subjected to self‐imposed kinematic constraints is chosen as a representative model for this type of structure. The corresponding equations of motion are non‐linear and have coefficients with step discontinuities; they are generally non‐autonomous and comprise, in effect, 2N sets of N governing equations for an N degree‐of‐freedom model. Linearized time histories are presented for one and two degree‐of‐freedom systems. As expected, the response modes of the systems are poorly conditioned; small changes in input or geometry (or both) can create large changes in system response. By examining limiting cases of survival and failure for both analytical and probabilistic responses, some apparent trends in system behaviour have been discovered.
Dynamics of resilient‐friction base isolator (R‐FBI)
Authors: Mostaghel N. , Khodaverdian M. 
Published: March 2007

AbstractThe Resilient‐Friction Base Isolator (R‐FBI) is composed of a set of flat rings which can slide on each other with a central rubber core and/or peripheral rubber cores. In this base isolator the interfacial friction force acts in parallel with the elastic force in the rubber. It combines the beneficial effect of friction damping with that of the resiliency of rubber. The rubber cores distribute the sliding displacement and velocity along the height of the R‐FBI. They do not carry any vertical loads and are not vulcanized to the sliding rings.The system's analytical model and the computer experimental results for both horizontal and vertical components of recorded ground motions and various levels of friction and damping are presented. These results clearly demonstrate the R‐FBI's potential as an effective aseismic base isolator.
Elimination of spurious higher‐mode response in pseudodynamic tests
Authors: Shing Pui‐Shum B. , Mahin Stephen A. 
Published: March 2007

AbstractIn a pseudodynamic test, errors in restoring‐force feedback are introduced into numerical computations. Some of these errors can excite the higher‐frequency response of the specimen. In this paper, the use of viscous and numerical dampings to eliminate spurious higher‐frequency effects is studied. Since the tangent stiffness of a non‐linear specimen cannot be measured accurately, initial‐stiffness‐dependent viscous damping is considered. In addition, an explicit integration algorithm with desired numerical damping properties is proposed and examined. The analytical and numerical studies presented indicate that viscous‐damping properties can be substantially changed by non‐linear deformations. For this reason, the use of numerical damping appears to be more advantageous.
Amplification factors for inelastic dynamic p–Δ effects in earthquake analysis
Authors: Bernal Dionisio 
Published: March 2007

AbstractIn the present study, the question of inelastic p–Δ effects is examined from the perspective of inelastic spectral ordinates. Inelastic acceleration response spectra are generated using a model which includes the effects of gravity; for each spectrum the ductility factor and the gravity load level (characterized by the stability coefficient) are held constant. Amplification spectra are generated by taking the ratio between spectra with and without gravity effects. The results are analysed statistically and a formula for the amplification factor as a function of the relevant parameters is obtained. Special care is taken to present a formulation that is simple and useful in the context of practical earthquake engineering design.Some currently used p–Δ amplification factors are discussed in the light of the results obtained.
The use of reduced finite element models in system identification
Authors: Hoff C. 
Published: April 2007

AbstractAn a priori, analytical model in system identification of vibrating structures is improved by input and output measurements with least square fitting. The structure is modelled by the finite element method. Finite element models usually need a large number of degrees of freedom to simulate a small number of lower spectrum eigenfrequencies with accuracy. The large finite element model is reduced to a subspace of significant eigenfrequencies. The size of the subspace is chosen with regard to the frequency content of the measured data and the accuracy of the large analytical model. An identification method is formulated for the large analytical model. This procedure improves system parameters in the matrices of the large model by measured input and output data with a least square functional. The objective function is consistently reduced, so that the whole identification procedure can be performed in the small subspace. The proposed reduction method permits very large and accurate analytical models to be used, and it decreases the computational cost of the identification procedure significantly. The computational efficiency is demonstrated on an in situ experiment of a radar tower.
Dynamic stability characteristics of liquid‐filled shells
Authors: Uras Rasim Aziz , Liu Wing Kam 
Published: April 2007

AbstractA Galerkin Finite Element formulation for the dynamic stability analysis of liquid‐filled shells is given in this paper. The coupling among the axial and circumferential modes is investigated. The dynamic stability characteristics of two liquid‐filled storage tanks subjected to vertical, horizontal and rocking seismic excitations are presented. It is shown that a tall tank tends to buckle at distinct frequencies; and for cos θ‐type ground excitation, cos 2θ, cos 3θ and cos 4θ are the dominant modes of failure. On the other hand, in a broad tank, buckling regions overlap each other. In particular, for cos θ‐type ground excitation, the dominant buckling modes are cos 6θ to cos 9θ, and also cos 12θ to cos 14θ.
Uniform magnitude re‐evaluation of European earthquakes associated with strong‐motion records
Authors: Ambraseys N. N. 
Published: April 2007

AbstractThis paper presents uniformly calculated surface‐wave magnitudes of over 400 earthquakes in the European area and adjacent regions associated with strong‐motion recordings. Seismic moments and body‐wave magnitudes are estimated also, so that they may be used in the derivation of attenuation laws. Using a more complete set of data the attenuation law derived for western North American earthquakes is modified for surface‐wave magnitudes.
Non‐linear earthquake‐response analysis of long‐span cable‐stayed bridges: Theory
Authors: Nazmy Aly S. , Abdel‐Ghaffar Ahmed M. 
Published: April 2007

AbstractThe non‐linear dynamic analysis of three‐dimensional long‐span cable‐stayed bridges when subjected to seismic loading is formulated. All possible sources of non‐linearity, such as cable sag, axial force‐bending moment interaction in bridge towers and girders and change of geometry of the whole bridge due to large displacements are considered in the analysis. Both cases of uniform and multiple‐support seismic excitations are considered in the non‐linear formulation of the problem. A tangent stiffness, iterative procedure is utilized to capture the the non‐linear seismic response. The non‐linear equations of motion are solved using a step‐by‐step integration technique in the real displacement coordinate space as well as in the modal coordinate space to save computational time.
Non‐linear earthquake‐response analysis of long‐span cable‐stayed bridges: Applications
Authors: Nazmy Aly S. , Abdel‐Ghaffar Ahmed M. 
Published: April 2007

AbstractThe dynamic non‐linear behaviour of three‐dimensional long‐span cable‐stayed bridges under seismic loadings is studied. The cases of multiple‐support as well as uniform seismic excitations of these long and flexible structures are considered. Different sources of non‐linearity for such bridges are included in the analysis, as outlined in the companion paper. In this accompanying analysis a tangent stiffness iterative procedure is utilized to estimate the non‐linear seismic response. Numerical examples are presented in which a comparison between a linear earthquake‐response analysis (based on the utilization of the tangent stiffness matrix of the bridge at the dead‐load deformed state which is obtained from the geometry of the bridge under gravity load conditions) and a non‐linear earthquake response analysis using the step‐by‐integration procedure is made. In these examples two three‐dimensional bridge models representing recent and future trends in cable‐stayed bridge design are utilized. The study sheds some light on the salient features of the seismic analysis and design of these long contemporary bridges. In addition, parameters affecting the seismic response of these bridges are discussed: other factors considered are non‐linearity, uniformity and spatial variation of ground motion inputs and structural configuration.
Stochastic response of suspension bridges to earthquake forces
Authors: Dumanoglu A. A. , Severn R. T. 
Published: April 2007

AbstractThe purpose of the paper is to study the applicability of stochastic methods for determining the response in the vertical plane of long‐span bridges to earthquakes. The bridges are of the modern type, with flexible towers, box‐decks and inclined hangers, Humber and Bosporus being used as the main examples, although some useful information is obtained by studying a small suspension footbridge. The input ground acceleration is that of the Pacoima Dam record of the 1971 San Fernando event, but use is also made of filtered white noise.Because the stochastic approach is essentially an attempt to abstract usable information which could otherwise be obtained from a lengthy time‐history approach, the procedure adopted here is to compare the same parameters obtained in these two ways, as far as possible. In particular, the maximum values of displacements and bending moments are considered.The essential question to be answered is whether the short length of earthquake records, coupled with the large natural periods of vibration of long‐span bridges, allows sufficient response information to be generated to make statistical parameters meaningful. The short‐span (50 m) footbridge gives no cause for concern here, but the detailed comparison with time‐history solutions shows that the stochastic approach for both Bosporus and Humber has to be cautiously assessed, particularly if some trailing zeros are not added to the earthquake record. However, general conclusions are not made, because only one earthquake record has been used.
Response of indeterminate two‐span beam to spatially varying seismic excitation
Authors: Harichandran Ronald S. , Wang Weijun 
Published: April 2007

AbstractIn order to examine the effect of the spatial variation of ground motion on the response of an indeterminate structure, the stochastic responses of a two‐span beam to spatially varying support excitations are analysed. A space‐time earthquake ground motion model that accounts for both coherency decay and seismic wave propagation is used to specify the support motions, and the results are compared with those for various simplified excitations that are commonly used in practice. The response is computed through a linear random vibration approach with the structure being modelled by finite elements. The results of the study indicate that, even for moderate lengths, the effect of the spatial variation of ground motion can be significant. The assumption of fully coherent support motions (same excitations at all supports or delayed excitations allowing only for wave propagation) may be overconservative for some beams and unconservative for others.
Mechanics and performance of a tied‐back wall under seismic loads
Authors: Neelakantan G. , Budhu Muniram , Richards R. 
Published: April 2007

AbstractIn this paper the stability of a tied‐back wall subjected to seismic loads is analysed for a predetermined mode of failure (rotation about the top of the wall) and the analysis is compared with data from tests on this type of wall using the seismic simulator at the State University of New York at Buffalo. We carried out a pseudo‐static analysis of the problem using the Mononobe‐Okabe earth pressure coefficients, wherein the dynamic effects due to the seismic loading are converted into equivalent static loads. The acceleration ratio at which the wall fails by rotation about the top was obtained by considering the moments due to the various lateral earth pressure resultants and the inertial forces induced in the soil due to the seismic loading.We found that the presence of wall friction on the passive side significantly enhances the stability of the flexible retaining wall under seismic loads. Thus, flexible retaining walls supporting dry cohesionless soil can be very efficient during earthquakes. Under moderate earthquakes, an increase in the depth of embedment increases the dynamic factor of safety significantly. However, beyond a certain acceleration ratio for a soil with a particular value of ø, any increase in the depth of emdedment has no effect in impeding failure, irrespective of any change in the geometry of the system. Seismic design charts are presented to evaluate the stability of, and to design, flexible retaining walls embedded in dry cohesionless soils under seismic loading.