bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyanometalate Cages with Exchangeable Terminal Ligands
Authors: Boyer Julie L. , Yao Haijun , Kuhlman Matthew L. , Rauchfuss Thomas B. , Wilson Scott 
Published: March 2007

AbstractThe coordination chemistry of the unusual metallo‐ligand Cs⊂[CpCo(CN)3]4[Cp*Ru]3 (Cs⊂Co4Ru3) is described with attention to the behavior of the ligand itself, its binding to Lewis‐acidic metal cations, and its ability to stabilize catalytically relevant Ru–PPh3 fragments. A series of tests demonstrate that the “rim” [CpCo(CN)3]– groups in Cs⊂Co4Ru3 are exchangeable. Upon treatment with [(MeC5H4)Co(CN)3]– (Co′) Cs⊂Co4Ru3 undergoes vertex exchange to give Cs⊂Co4–xCo′xRu3. Similarly the cage is degraded by CO. Most convincing, Cs⊂Co4Ru3 reacts with PhNH3OTf to precipitate the polymer PhNH3CpCo(CN)3 and form the molecular box [Cs⊂Co4Ru4]+. Treatment of Cs⊂Co4Ru3 with [M(NCMe)x]PF6 (M = Cu, Ag) gave the Lewis acidic cages {Cs⊂[CpCo(CN)3]4[Cp*Ru]3M(NCMe)}PF6, which reacted with tertiary phosphane ligands to give adducts [Cs⊂Co4Ru3M(PPh3)]PF6. Lewis acidic octahedral vertices were installed using Fe, Ni, and Ru reagents. The boxes [Cs⊂Co4Ru3M(NCMe)3]2+ (M = Ni, Fe) formed readily from the reaction Cs⊂Co4Ru3 with [Ni(NCMe)6](BF4)2 and [Fe(NCMe)6](PF6)2. Displacement of the MeCN ligands gives [Cs⊂Co4Ru3Ni(9‐ane‐S3)](BF4)2. A series of boxes were prepared by the reaction of Cs⊂Co4Ru3 and RuCl2(PPh3)3, RuHCl(PPh3)3, and [(C6H6)Ru(NCMe)3](PF6)2. The derivative of the hydride, [Cs⊂Co4Ru3Ru(NCMe)(PPh3)2](PF6)2, was characterized crystallographically.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Nanovehicles Based Bioassay Labels
Authors: Liu Guodong , Wang Jun , Wu Hong , Lin Yingying , Lin Yuehe 
Published: March 2007

AbstractIn this article, we review recent advances of our group in nanoparticle labels based bioassay. Apoferritin and silica nanoparticles have been used as nanovehicles to load large amount of markers for highly sensitive bioassay. Markers loaded apoferritin, apoferritin‐templated metallic phosphate nanoparticles, and poly[guanine] coated silica nanoparticles have been prepared, characterized and used as labels for highly sensitive bioassay of protein and DNA. Dissociation and reconstitution characteristics at different pH as well as the special cavity structure of apoferritin nanovehicle provides a simple and convenient route to prepare versatile nanoparticle labels and avoid the complicated and tedious synthesis process of conventional nanoparticle labels. The optical and electrochemical characteristics of the prepared nanoparticle labels are easily controlled by loading different optical or electrochemical markers. Additionally, the use of apoferritin nanovehicle as template for synthesis of metallic phosphate nanoparticle labels offers fast route to prepare uniform‐size metallic nanoparticle labels for electrochemical bioassay and avoids the traditional harsh dissolution conditions to dissolve metallic nanoparticle tags (that is, the strong‐acid dissolution of quantum dots and gold nanoparticles) during the stripping analysis step. Silica nanoparticle has also been used as nanovehicle to carry thousands of poly[guanine] tracers, which was used to enhance the oxidation current of Ru(bpy)$\rm{ {_{3}^{2+}}}$, resulting in enhanced sensitivity of electrochemical immunoassay. The new nanovehicle‐based labels have been used for highly sensitive electrochemical detection of DNA and protein biomarkers, such as tumor necrosis factor‐alpha (TNF‐α). The high sensitivity and selectivity make these labels a useful addition to the armory of nanoparticle‐based bioassay. The new nanovehicles based labels hold great promise for multiplex protein and DNA detection and for enhancing the sensitivity of other bioassays.
Nanoparticle‐Based Electrochemical Bioassays of Proteins
Authors: Wang Joseph 
Published: March 2007

AbstractThis article reviews a variety of new nanoparticle/biomolecule assemblies for advanced electrical detection of proteins. Effective methods for the reliable and trace measurements of proteins are highly desired for facilitating the diagnosis of disease states and improving drug discovery. Ultrasensitive monitoring of biomolecular interactions of proteins is particularly challenging owing to the absence of PCR‐like amplification protocols and their greater nonspecific binding to solid supports compared to oligonucleotides. Recent activity has led to innovative and powerful nanoparticle‐based immunoassays and aptamer bioassays of proteins based on a variety of electrochemical detection schemes. The enormous signal enhancement associated with the use of nanoparticle amplifying labels and with the formation of nanoparticle‐protein assemblies provides the basis for ultrasensitive electrochemical detection of proteins. Such protocols rely on the use of colloidal gold tags, semiconductor (quantum dot) tracers, ‘carrier’ (amplification) nanomaterials, or magnetic (separation) beads, in connection to electrochemical stripping measurement of the metal tag. Remarkable ‘PCR‐like’ sensitivity has been achieved by coupling particle‐based amplification units and various amplification processes. The use of nanocrystal tracers for designing electrochemical coding protocols for detecting multiple proteins will also be documented.
Doubly Modified Electrodes for the Selective Determination of Dopamine in the Presence of Interfering Species
Authors: Xu Guang‐Ri , Zhang Y. P. , Tao Jian Zhong , Kim Sunghyun , Bae Zun‐Ung 
Published: March 2007

AbstractIn this paper, we describe the double modification of the glassy carbon electrode surface with two polymer layers for the selective determination of dopamine. The first layer was the electropolymerized macrocyclic nickel complex acting as an electrocatalyst for the dopamine oxidation and the second layer the polyurethane benzyl L‐glutamate (PUBLG) for screening interfering species. Hydrolyzed PUBLG (PU‐C) showed a better screening effect. Thus prepared GC/Ni(II) complex film/PU‐C electrodes exhibited improved selectivity and better performance than unmodified counterparts, with minimum passivation even in the presence of large excess of interferents. Under optimal conditions, these electrodes showed a linear response over a dopamine concentration range of 2.5×10−7 and 3.0×10−5 M with a correlation coefficient of 0.999 and detection limit (at S/N=3) of 8.0×10−8 M. The recoveries of dopamine in the 5‐fold diluted human urine sample were 96.9% for 4 measurements. The rate constant for the dopamine oxidation measured by the rotating disk electrode was found to be 1.1×10−3 cm s−1.
Natural frequencies and modes of rhombic mindlin plates
Authors: Raju K. Kanaka , Hinton E. 
Published: March 2007

AbstractThe natural frequencies and mode shapes of thin and moderately thick rhombic plates are obtained using a 9‐noded Lagrangian quadrilateral isoparametric plate element based on Mindlin's theory. The effects of rotatory inertia are included. Plates with a wide range of skew angles and boundary conditions are considered and wherever possible the present results are compared with earlier published work.
Free and steady state vibration of non‐linear structures using a finite element–non‐linear eigenvalue technique
Authors: Wellford L. Carter , Dib G. M. , Mindle W. 
Published: March 2007

AbstractThe problem of free vibration of non‐linear structures is considered initially. It is shown that this problem can be represented as a non‐linear eigenvalue problem. Variational principles for non‐linear eigenvalue problems are defined. These variational principles are implemented with finite element models to define numerical approximations for the free vibration problem. The solution of these approximate equations provides a set of non‐linear modal vectors and natural frequencies which vary with the amplitude of the solution. The non‐linear eigenvalue parameters can be used in modal expansion approximations for the non‐linear transient or steady state response of structural systems. To demonstrate the proposed techniques the free vibration and steady state vibration characteristics of a geometrically non‐linear circular plate are determined.
Collapse of a model for ductile reinforced concrete frames under extreme earthquake motions
Authors: Takizawa Haruo , Jennings Paul C. 
Published: March 2007

AbstractA mathematical formulation is presented for modelling the dynamic process of failure of a class of ductile, moment‐resisting, reinforced concrete (R/C) frame buildings when subjected to intense earthquake motion. The formulation includes the geometrically non‐linear term that accounts for the destabilizing action of gravity. In many cases of practical interest, in which the structures have strong columns and weak girders, the employed method of synthesizing the restoring force properties can provide a satisfactory description of the structural deformation at large deflections. By modelling approximately the effects of gravity, cracking, yielding and degradation of stiffness, the study is intended to aid the understanding of the process of failure in this type of ductile R/C structure, and to relate the mechanics of collapse to characteristics of the excitation. The collapse of R/C frames having strong girders and weak columns, which can develop sway mechanisms at a single storey, is not considered in this study.Special examination is made of the capacity to resist short‐duration motions consisting of a few pulses versus the capacity to resist motions of longer duration. For the class of structures modelled, the results indicate an extremely low destructive capability associated with short‐duration motions, even when they have very high accelerations. The application in research of a two‐parameter characterization of the severity of ground motion in terms of intensity and duration is also examined.
Structural identification in the frequency domain from earthquake records
Authors: McVerry Graeme H. 
Published: March 2007

AbstractA method has been developed to identify the parameters of the lower modes of a linear, time‐invariant model of a structure from its recorded earthquake response. The identification is performed by selecting the parameters to obtain a least squares fit over a specified frequency band between the unsmoothed, complex‐valued finite Fourier transform of the recorded acceleration response and the corresponding transform calculated from the response of the model. By including the effects of the initial and final conditions in the analysis, only a portion of the recorded excitation and response acceleration histories need be considered. The method is demonstrated first by an application to generated test data, and then to measured earthquake response.
Optimum absorber parameters for simple systems
Authors: Warburton G. B. , Ayorinde E. O. 
Published: March 2007

AbstractIn the classical problem a damped one degree‐of‐freedom absorber system is attached to a main system, which has one degree of freedom and is undamped. The optimum values of absorber stiffness and damping, which will minimize the resonant response of the main mass, are well known. In this paper the effect on these optimum conditions of light damping in the main system is studied. The authors show that optimum parameters for absorbers, which are attached to beams and plates, can be obtained simply and accurately from those for an equivalent one degree‐of‐freedom main system. This depends upon the concept of an effective mass for the elastic body and the representation of its response by the single relevant mode. It will be shown in a later paper that for more complex elastic bodies such as cylindrical shells, for which the natural frequencies are more closely spaced, these simple concepts do not predict accurately optimum absorber parameters.
Seismic torsional provisions for dynamic eccentricity
Authors: Tso W. K. , Dempsey K. M. 
Published: March 2007

AbstractA study is made of the dynamic torsional response of a single mass partially symmetric system to ground excitation. Using the response spectrum technique, the torsional response and dynamic eccentricity are determined as functions of the eccentricity of the system and its uncoupled frequency ratio. It is shown that the dynamic eccentricity can best be expressed as a bilinear function of eccentricity. For the critical condition which occurs when the uncoupled frequency ratio is unity, a comparison is made with the torsional provisions of five seismic codes (Canada, Mexico, New Zealand, ATC3 and Germany). It is shown that the first four codes underestimate the torsional moment, and also the edge displacement of the system, significantly when the eccentricity is small and the uncouped torsional and lateral frequencies are close.
Seismic qualification of electrical equipment using a uniaxial test
Authors: De Silva Clarence W. 
Published: March 2007

AbstractThe analytical development of a uniaxial test for the seismic qualification of electrical equipment is presented. This method comprises a single test using a uniaxial excitation having certain minimum intensity applied at the base of the test package in a predetermined optimal direction. It is anticipated that the proposed procedure would be more economical and less time consuming than, but functionally equivalent to, presently employed series of multiaxial tests. The test is shown to be superior to the symmetric tests. The determination of the minimum intensity of the optimal orientation of the base excitation requires a preliminary frequency response test which is a slightly more elaborate version of the sine sweep test presently employed to determine the resonance frequencies of the test package. A simulated test is presented to compare the proposed method with the uncorrelated triaxial test and the symmetric uniaxial test.
The effect of column mass on shear building vibrations
Authors: Lubliner J. 
Published: March 2007

AbstractIn the usual assignment of mass for shear building models, the mass of the columns is lumped with the mass of the floor at each floor level. In order to account for frequencies of modes higher than N in an N‐storey building, however, additional column masses must be identified. In this note, such additional masses are located at the mid‐height of each column, and the characteristics of the shapes and frequencies of the resulting higher mode set are investigated.
Parkfield, California, Earthquake of June 1966: Interpretation of the strong motion records
Authors: Shoja‐Taheri Jafar 
Published: March 2007

AbstractA detailed seismological interpretation of the strong motion records was attempted for the 1966 Parkfield earthquake, California. Velocity and displacement traces integrated from the corresponding recorded accelerograms were found most valuable in studying the earthquake mechanism and wave forms. A double‐couple right‐lateral strike — slip mechanism (along the San Andreas fault) is consistent with the recorded direct S‐waves originating from the hypocentre. High energy arrivals observed on the velocity traces are interpreted as S‐waves (‘stopping phases’) that originated at the termination of the rupture towards the south‐east of the San Andreas fault. A double‐couple left‐lateral strike–slip mechanism is suggested as the cause of this rupture termination.From particle velocity diagrams of the stopping phases in the horizontal plane, the rupture length was found to be between 20 and 28 km. Corresponding rupture velocities are estimated to be 2·5 ± 0·1 and 3·1 ± 0·5 km/s. The inference from the strong motion records is that Love waves were more excited at the south‐western than the north‐eastern side of the fault, whereas the Rayleigh waves were more energetic at the north‐eastern than the south‐western side of the fault.
Seismic response of precast concrete walls
Authors: Becker James M. , Llorente Carlos , Mueller Peter 
Published: March 2007

AbstractLarge panel precast concrete structures are built in major seismic regions throughout the world. The seismic behaviour of such structures is strongly dependent upon the characteristics of both the horizontal and vertical connections. The limiting behaviour of precast systems, however, is basically dependent upon the horizontal connection. The influence of horizontal connections can be studied in terms of the behaviour of a simple wall—a vertical stack of panels having only horizontal connections.This paper reports on research into the seismic behaviour of simple precast concrete walls. The research was carried out through the development of computer‐based modelling techniques capable of including the typical behavioural characteristics associated with horizontal joints. The model assumes that all non‐linear, inelastic behaviour is concentrated in the connection regions and that the precast panels remain linear elastic. This assumption allows the precast panels to be modelled as statically condensed ‘super‐elements’ and the connection regions as interface elements. The above modelling technique allows for non‐linear‐inelastic seismic analysis that is capable of handling both rocking type motions throughout the height of the structure and slippage due to shear in the plane of the connection.A series of parametric studies are presented to illustrate the potential influence of rocking and slip on precast walls with both regular reinforcement and post‐tensioning. These studies demonstrate the period elongation associated with the nonlinear‐elastic rocking phenomenon. Shear slip is found to occur only when friction coefficients are extremely low or when the normal forces across the connections are low. This latter case occurs only in low buildings or in the upper floors of tall buildings.The paper concludes with a brief discussion of the design implications of these results. Particular attention is paid to the problems stemming from the force concentrations associated with rocking and shear slip.
Effects of horizontally propagating waves on the response of structures with a soft first storey
Authors: Wolf J. P. , Obernhuber P. 
Published: March 2007

AbstractThe influence of insulating a structure with a soft first storey (horizontally elastic or elastoplastic or horizontally and vertically elastic) is investigated for horizontally propagating waves. A comprehensive parametric study for a simple structure excited by SH‐ and R‐waves is performed. A reactor building is examined for a horizontally propagating historic earthquake. Compared to a conventional structure, travelling‐wave effects become more important for R‐waves in a structure with a horizontal soft first storey. For SH‐waves, the opposite applies.
Hydrodynamic pressure on arch dams—by a mapping finite element method
Authors: Nath B. 
Published: March 2007

AbstractA novel Finite Element Method (FEM) is proposed for the analysis of the uncoupled hydrodynamic pressures generated on arch dams due to a steady‐state ground acceleration. In this method the equation governing hydrodynamic pressures and also the prescribed boundary conditions are all transformed from the Cartesian space to a logarithmically condensed cylindrical polar space; in this process the physical configuration of the reservoir‐dam is also mapped into an ‘image’ domain. The transformed governing equation is then solved in the image domain, subject to the transformed boundary conditions, using standard finite elements. Because physical dimensions are logarithmically condensed in the image space, the proposed method is particularly suitable for dealing with large or very large aspect‐ratio reservoir‐dam systems, economically and efficiently.The high degree of accuracy which the proposed method is capable of, and also the simple way in which it can be applied to complex reservoir‐dam shapes, have been demonstrated by means of examples. The method has also been applied to study the uncoupled hydrodynamic pressures on the upstream face of a cylindrical arch dam, generated by a steady‐state vertical ground acceleration.
A replacement for the srss method in seismic analysis
Authors: Wilson E. L. , Der Kiureghian A. , Bayo E. P. 
Published: March 2007

AbstractIt is well‐known that the application of the Square‐Root‐of‐Sum‐of‐Squares (SRSS) method in seismic analysis for combining modal maxima can cause significant errors. Nevertheless, this method continues to be used by the profession for significant buildings. The purpose of this note is to present an improved technique to be used in place of the SRSS method in seismic analysis.A Complete Quadratic Combination (CQC) method is proposed which reduces errors in modal combination in all examples studied. The CQC method degenerates into the SRSS method for systems with well‐spaced natural frequencies. Since the CQC method only involves a small increase in numerical effort, it is recommended that the new approach be used as a replacement for the SRSS method in all response spectrum calculations.
Dynamic response of flexible rectangular foundations on an elastic half‐space
Authors: Iguchi M. , Luco J. E. 
Published: March 2007

AbstractAn approximate method for the analysis of the dynamic interaction between a flexible rectangular foundation and the soil with consideration of the out‐of‐plane deformation of the foundation is presented. The procedure is based on an extension of the subdivision method developed by Wong and Luco for rigid foundations.Numerical results describing the influence of the flexibility of the foundation on the vertical and rocking impedance functions and on the contact stresses between the foundation and the soil are presented. The possibility of representing a flexible foundation by an equivalent rigid foundation having the same force‐displacement relationships is also discussed. The results obtained indicate that at low frequencies, the dynamic stiffness coefficients for flexible foundations are lower than those for a rigid foundation of the same area. At higher frequencies the opposite behaviour is observed. The radiation damping coefficients for flexible foundations are significantly lower than those for a rigid foundation of the same area.
Longitudinal vibration of non‐homogeneous earth dams
Authors: Abdel‐Ghaffar Ahmed M. , Koh Aik‐Siong 
Published: March 2007

AbstractTwo‐dimensional analytical elastic models are developed for evaluating dynamic characteristics, namely natural frequencies and modes of vibration of a wide class of earth dams in a direction parallel to the dam axis. In these models the non‐homogeneity of the dam materials is taken into account by assuming a specific variation of the stiffness properties along the depth (due to the continuous increase in confining pressure). In addition, both shear and normal (axial) deformations are considered. Cases having constant elastic moduli, linear and trapezoidal variations of elastic moduli, and elastic moduli increasing as the one‐half, one‐third, two fifths, and a general (l/m)th powers of the depth are studied. Dynamic properties of three real earth dams in a seismically active area (Southern California) estimated from their earthquake records (input ground motion and crest response in the longitudinal direction) as well as results from full‐scale dynamic tests on one of these dams (including ambient and forced vibration tests) are compared with those from the suggested models. It was found that the models in which the shear modulus and the modulus of elasticity of the dam material vary along the depth are the most appropriate representations for predicting the dynamic characteristics. The agreement between the experimental and earthquake data and the theoretical results from some of the models is reasonably good.