bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syringe pumped high speed flow cytometry of oceanic phytoplankton
Authors: Zubkov Mikhail V. , Burkill Peter H. 
Published: September 2006

AbstractBackground:Nanophytoplankton (2–20 μm) are less numerous than picophytoplankton (<2 μm) in the oceans but their biomass and production are comparable and sometimes higher. The accuracy of cytometry‐based enumeration of phytoplankton ultimately depends on cell abundance and sample flow rate. Commercial flow cytometers in which sheath and core streams are driven by air pressure cannot produce sufficiently high, stable sample flow rate. The present study demonstrates the applicability of a syringe pump for flow cytometric enumeration of oceanic nanophytoplankton on two meridional transects across the Atlantic Ocean.Methods:Commercially available syringe pumps were used to deliver live phytoplankton samples into a flow cell of standard flow cytometers (FACSort, FACSCalibur, BD) with increased flow rate of > 1.0 ml min−1 compared to the normal air pressure sample delivery of < 0.1 ml min−1. An auxiliary application of syringe pump flow cytometry for calibrating 0.5 μm bead concentration standards is also discussed.Results:The results demonstrated that flow cytometry of samples injected at rates above 0.1 ml min−1 is achievable and worthwhile. Counts of phytoplankton in air and syringe pumped samples agreed closely. Syringe pumping of samples offered a broader range of flow rates up to 0.8–1.0 ml min−1 without detrimental effect on flow cytometric enumeration of cells. The increased number of coincidences at high flow rates led to an approximate 10% decrease of Cyanobacteria counts when the acquisition rate approached 1,000 particles s−1, but seemed to have a lesser effect on counting rarer phytoplankton. The syringe pump flow cytometry allowed enumeration of phytoplankton groups at concentrations of 5–100 cells ml−1, cell concentrations equivalent to those of Cyanobacteria in the twilight deep ocean.Conclusion:The proposed syringe pump modification of a FACS instrument represents a significant improvement for accurate enumeration of the less abundant phytoplankton and so gives better estimations of phytoplankton distribution and standing stocks. © 2006 International Society for Analytical Cytology
Synthesis of New Phenanthroline‐Based Heteroditopic Ligands – Highly Efficient and Selective Fluorescence Sensors for Copper(II) Ions
Authors: Comba Peter , Krämer Roland , Mokhir Andriy , Naing Kyaw , Schatz Erik 
Published: September 2006

AbstractThe heteroditopic phenanthroline derivatives 5,6‐bis(2‐pyridylcarboxamido)‐1,10‐phenanthroline (H2L1) and 5,6‐bis[(4‐methoxy‐2‐pyridyl)carboxamido]‐1,10‐phenanthroline (H2L2) have been prepared and characterized, together with their luminescent ruthenium(II) complexes [Ru(bpy)2(H2L1,2)](PF6)2 and [Ru(H2L1)3](PF6)2 and the corresponding iron(II) complex [Fe(H2L1)3](PF6)2. In these complexes, the metal ion is coordinated by the bidentate phen site of H2L. The luminescence of the ruthenium complexes (λex = 450 nm, λem ca. 620 nm) is completely quenched by Cu2+ ions in the micromolar concentration range and, to a lesser extent, by other metal ions. At pH 5, the response of the luminescent sensors is highly Cu2+‐selective. Heterodinuclear complexes [Ru(bpy)2(LM)](PF6)2, [Ru(LM)3](PF6)2, and [Fe(LM)3](PF6)2 have been isolated for M = Cu2+, Ni2+, Co2+, and Pd2+. It is suggested that M is coordinated to the tetradentate N4 site of L by two deprotonated amide N atoms and two pyridyl groups. This coordination type is confirmed by the EPR spectrum of the compound [RuII(bpy)2(L1CuII)](PF6)2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Torsional balance of plan‐asymmetric structures with frictional dampers: experimental results
Authors: Vial Ignacio J. , de la Llera Juan C. , Almazán José L. , Ceballos Víctor 
Published: September 2006

AbstractThis investigation deals with the measured seismic response of a six‐storey asymmetric structural model with frictional dampers. Its main objective is to experimentally prove the concept of weak torsional balance for mass‐ and stiffness‐eccentric model configurations. The goal is to control the torsional response of these asymmetric structures and to achieve, if possible, a weak form of torsional balance by placing the so‐called empirical centre of balance (ECB) of the structure at equal distance from the edges of the building plan. The control of the dynamic response of asymmetric structures is investigated herein by using steel–teflon frictional dampers. As expected from theory, experimental results show that the mean‐square and peak displacement demand at the flexible and stiff edges of the plan may be similar in magnitude if the dampers are optimally placed. Frictional dampers have proven equally effective in controlling lateral‐torsional coupling of torsionally flexible as well as stiff structures. On the other hand, it is shown that impulsive ground motions require larger frictional capacities to achieve weak torsional balance. Copyright © 2006 John Wiley & Sons, Ltd.
Yielding oscillator subjected to simple pulse waveforms: numerical analysis & closed‐form solutions
Authors: Mylonakis George , Voyagaki Elia 
Published: September 2006

AbstractNumerical and analytical solutions are presented for the elastic and inelastic response of single‐degree‐of‐freedom yielding oscillators to idealized ground acceleration pulses. These motions are typical of near‐fault earthquake recordings generated by forward rupture directivity and may inflict damage in the absence of substantial structural strength and ductility capacity. Four basic pulse waveforms are examined: (1) triangular; (2) sinusoidal; (3) exponential; and (4) rectangular. In the first part of the article, a numerical study is presented of the effect of oscillator period, strength, damping, post‐yielding stiffness and number of excitation cycles, on inelastic response. Results are presented in the form of dimensionless graphs and regression formulas that elucidate the salient features of the problem. It is shown that conventional R–µ relations may significantly underestimate ductility demand imposed by near‐fault motions.The second part of the article concentrates on elastic‐perfectly plastic oscillators. Closed‐form solutions are derived for post‐yielding response and associated ductility demand. It is shown that all three ground motion histories (i.e. acceleration, velocity, and displacement) control oscillator response—contrary to the widespread view that ground velocity alone is of leading importance. The derived solutions provide insight on the physics of inelastic response, which is often obscured by the complexity of numerical algorithms and actual earthquake motions. The model is evaluated against numerical results from near‐field recordings. A case study is presented. Copyright © 2006 John Wiley & Sons, Ltd.
Rigid‐plastic seismic design of reinforced concrete structures
Authors: Domingues Costa J. L. , Bento R. , Levtchitch Vsevolod , Nielsen M. P. 
Published: September 2006

AbstractIn this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed—the Rigid‐Plastic Seismic Design (RPSD) method. This is a design procedure based on Non‐Linear Time‐ History Analysis (NLTHA) for systems expected to perform in the non‐linear range during a lifetime earthquake event. The theoretical background is the Theory of Plasticity (Rigid‐Plastic Structures).Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required structural strength with respect to a pre‐defined performance parameter using a rigid‐plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing required strength throughout the structure.Any artificial considerations intended to adjust results according to empirical observations are avoided, which, from a conceptual point of view, is considered to be an advantage over other simplified design procedures for seismic design.The procedure is formulated using a step‐by‐step format followed by a design example of a 4‐storey‐R/C‐plane‐frame. Results are compared with refined NLTHA and found to be extremely encouraging. Copyright © 2006 John Wiley & Sons, Ltd.
Re‐shaping hysteretic behaviour—spectral analysis and design equations for semi‐active structures
Authors: Rodgers Geoffrey W. , Mander John B. , Geoffrey Chase J. , Mulligan Kerry J. , Deam Bruce L. , Carr Athol 
Published: September 2006

AbstractSemi‐active dampers offer significant capability to reduce dynamic wind and seismic structural response. A novel resetable device with independent valve control laws that enables semi‐active re‐shaping of the overall structural hysteretic behaviour has been recently developed, and a one‐fifth scale prototype experimentally validated. This research statistically analyses three methods of re‐shaping structural hysteretic dynamics in a performance‐based seismic design context. Displacement, structural force, and total base‐shear response reduction factor spectra are obtained for suites of ground motions from the SAC project. Results indicate that the reduction factors are suite invariant. Resisting all motion adds damping in all four quadrants and showed 40–60% reductions in the structural force and displacement at the cost of a 20–60% increase in total base‐shear. Resisting only motion away from equilibrium adds damping in quadrants 1 and 3, and provides reductions of 20–40%, with a 20–50% increase in total base‐shear. However, only resisting motion towards equilibrium adds damping in quadrants 2 and 4 only, for which the structural responses and total base‐shear are reduced 20–40%. The spectral analysis results are used to create empirical reduction factor equations suitable for use in performance based design methods, creating an avenue for designing these devices into structural applications. Overall, the reductions in both response and base‐shear indicate the potential appeal of this semi‐active hysteresis sculpting approach for seismic retrofit applications—largely due to the reduction of the structural force and overturning demands on the foundation system. Copyright © 2006 John Wiley & Sons, Ltd.
Earthquake fault rupture—shallow foundation interaction in undrained soils: a simplified analytical approach
Authors: Tolga Yilmaz M. , Paolucci Roberto 
Published: September 2006

AbstractThe interaction between normal or reverse fault ruptures and shallow foundations resting on a homogeneous undrained soil layer is investigated. After performing a thorough set of non‐linear finite element simulations, three simple kinematic mechanisms are proposed to predict the conditions for the fault rupture to be diverted by the foundation. The results obtained by both numerical and analytical approaches are in good agreement, and support the adequacy of the proposed mechanisms.A relationship is established for assessing the minimum foundation bearing load needed for diversion of the fault rupture trace, either normal or reverse. This relationship is proved to be independent of the fault type and dip angle, so that it can be applied easily for engineering applications, even in the absence of specific tectonic information. Copyright © 2006 John Wiley & Sons, Ltd.
Real‐time hybrid experiments with Newmark integration, MCSmd outer‐loop control and multi‐tasking strategies
Authors: Bonnet P. A. , Lim C. N. , Williams M. S. , Blakeborough A. , Neild S. A. , Stoten D. P. , Taylor C. A. 
Published: September 2006

AbstractReal‐time hybrid testing is a promising technique for experimental structural dynamics, in which the structure under consideration is split into a physical test of key components and a numerical model of the remainder. The physical test and numerical analysis proceed in parallel, in real time, enabling testing of critical elements at large scale and at the correct loading rate. To date most real‐time hybrid tests have been restricted to simple configurations and have used approximate delay compensation schemes. This paper describes a real‐time hybrid testing approach in which non‐linearity is permitted in both the physical and numerical models, and in which multiple interfaces between physical and numerical substructures can be accommodated, even when this results in very stiff coupling between actuators. This is achieved using a Newmark explicit numerical solver, an advanced adaptive controller known as MCSmd and a multi‐tasking strategy. The approach is evaluated through a series of experiments on discrete mass–spring systems. Copyright © 2006 John Wiley & Sons, Ltd.
A semi‐analytic approach to retrieve the unitary impulse response function
Authors: Chen Kui‐Fu , Zhang Sen‐Wen 
Published: September 2006

AbstractTwo kinds of errors occur in numerically transforming the transfer function (TF) to the unitary impulse response function (UIRF), the truncating error due to ignoring high frequency band contribution, and the discrete error due to numerical integration. The truncating error becomes prevailing if the TF attenuating trend is slow as the frequency approaches infinity. A semi‐analytic approach is presented to alleviate this error. This approach dissects the whole frequency axis symmetrically into three bands, the central band, and two side bands extending to infinity. The contribution from the central band is calculated numerically, while the TF over the side bands is approximated as a simple function with an explicitly known inverse Laplace transform. This approach can overcome the Gibbs oscillation in computing the UIRF for a slowly attenuating TF, as is verified by the numerical examples studied here. Copyright © 2006 John Wiley & Sons, Ltd.
Shaking table model test on Shanghai World Financial Center Tower
Authors: Lu Xilin , Zou Yun , Lu Wensheng , Zhao Bin 
Published: September 2006

AbstractThe height of 101‐storey Shanghai World Financial Center Tower is 492m above ground making it possible the tallest building in the world when completed. Three parallel structural systems including mega‐frame structure, reinforced concrete and braced steel services core and outrigger trusses, are combined to resist vertical and lateral loads. The building could be classified as a vertically irregular structure due to a number of stiffened and transfer stories in the building. Complexities related to structural system layout are mainly exhibited in the design of services core, mega‐diagonals and outrigger trusses. According to Chinese Code, the height 190 m of the building clearly exceeds the stipulated maximum height of for a composite frame/reinforced concrete core building. The aspect ratio of height to width also exceeds the stipulated limit of 7 for seismic design intensity 7. A 1/50 scaled model is made and tested on shaking table under a series of one and two‐dimensional base excitations with gradually increasing acceleration amplitudes. This paper presents the dynamic characteristics, the seismic responses and the failure mechanism of the structure. The test results demonstrate that the structural system is a good solution to withstand earthquakes. The inter‐storey drift and the overall behaviour meet the requirements of Chinese Design Code. Furthermore, weak positions under seldom‐occurred earthquakes of seismic design intensity 8 are found based on the visible damages on the testing model, and some corresponding suggestions are proposed for the engineering design of the structure under extremely strong earthquake. Copyright © 2006 John Wiley & Sons, Ltd.
Feathers and ‘feather‐like’ integumentary structures in Liaoning birds and dinosaurs
Authors: Fucheng Zhang , Zhonghe Zhou , Dyke Gareth 
Published: September 2006

AbstractWe provide an overview of the known feather and other ‘feather‐like’ integumentary structure types known to‐date in the birds and dinosaurs from the Cretaceous rocks of Liaoning, NE China. These feather‐types are classified and compared with similar structures seen in Mesozoic and extant birds. We consider that integumentary feathers and ‘feather‐like’ structures fall within two major structural categories (‘shafted’ and ‘non‐shafted’). Comments are also made on the possible aerodynamic or insulating function of leg and tail feathers in Mesozoic birds and theropods. Copyright © 2006 John Wiley & Sons, Ltd.
Biological responses to multilayered DNA‐coatings
Authors: van den Beucken J. J. J. P. , Walboomers X. F. , Vos M. R. J. , Sommerdijk N. A. J. M. , Nolte R. J. M. , Jansen J. A. 
Published: September 2006

AbstractThis study was performed to evaluate the basic biological response to deoxyribonucleic acid (DNA)‐based coatings for soft tissue implants. To that end, in vitro experiments were used to study their cytocompatibility, and in vivo subcutaneous implantation studies with transponders in a rat model were performed to evaluate their histocompatibility. The DNA‐based coatings were fabricated using the electrostatic self‐assembly technique using cationic poly‐D‐lysine or poly‐allylamine hydrochloride and anionic DNA. Noncoated substrates served as controls. In vitro, the behavior of primary rat dermal fibroblasts was assessed in terms of cell proliferation and morphology. Both types of multilayered DNA‐coatings significantly increased rat dermal fibroblast proliferation without altering the morphological appearance of the cells. The tissue response to multilayered DNA‐coatings was assessed using an in vivo rat model, in which transponders were inserted subcutaneously for 4 and 12 weeks. No macroscopic signs of inflammation or adverse tissue reactions were observed at implant retrieval. Histological analyses demonstrated a uniform tissue response to all types of implants. All implants were encapsulated in a fibrous tissue capsule without intervening inflammatory cells at the implant surface. Histomorphometrically, multilayered DNA‐coatings induced fibrous tissue capsules with similar quality and thickness compared to noncoated controls. In addition, all fibrous tissue capsules showed similar expression of α‐smooth muscle actin. This study demonstrates that multilayered DNA‐coatings are cytocompatible and histocompatible, and justifies further research on their functionalization with biologically active compounds to modulate tissue responses. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Polypeptide multilayer nanofilm artificial red blood cells
Authors: Palath Naveen , Bhad Sujaykumar , Montazeri Reza , Guidry Christopher A. , Haynie Donald T. 
Published: September 2006

AbstractReliable encapsulation of hemoglobin (Hb) within polypeptide multilayer nanofilms has been achieved by a template‐based approach, and protein functionality has been demonstrated postencapsulation. The method is general in scope and could be useful for many other encapsulants. Met‐Hb was adsorbed onto 5 μm‐diameter CaCO3microparticles, and the Hb‐coated particles were encapsulated within a multilayer nanofilm of poly(L‐glutamic acid) (PLGA) and poly(L‐lysine) (PLL) by layer‐by‐layer assembly. The CaCO3templates were then dissolved within the PLGA/PLL nanofilms by addition of ethylenediaminetetraacetic acid. Encapsulation of Hb was proved by fluorescence microscopy, the pH‐dependence of retention of Hb was determined by visible wavelength absorbance, and conversion of the encapsulated met‐Hb to deoxy‐Hb and oxy‐Hb was demonstrated by spectroscopic analysis of the Soret absorption peak under various conditions. It thus has been shown that control of Hb oxygenation within polypeptide multilayer nanofilm artificial cells is possible, and that Hb thus encapsulated can bind, release, and subsequently rebind molecular oxygen. This work therefore represents an advance in the development of polypeptide multilayer film artificial red blood cells. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Different outcomes in urethral reconstruction using elastin and collagen patches and conduits in rabbits
Authors: Xie Hua , Campbell Carmen E. , Shaffer Brian S. , Gregory Kenton W. 
Published: September 2006

AbstractObjectives: To study the feasibility of urethral reconstruction with two urethroplasty techniques using an elastin and collagen heterograft in rabbits. Materials and Methods: Fifty‐two male rabbits were studied. Two types of injury, (1) a 1.5 ×× 0.6 cm2 semicircumferential defect; (2) a 1.5 cm segmental defect of the penile urethra, were created and repaired using size‐matched elastin and collagen patches or tubed conduits. Urethral repair by primary closure for the type 1 injury and a tubularized autologous bladder mucosal graft for the type 2 injury served as controls. At 3 months, urethral diameter was measured with retrograde urethrography. The animals were then euthanized for histological examination. Results: The postoperative complication rate was significantly higher in the urethral reconstructions using tubed collagen (83%) and elastin (50%) grafts compared to the patch onlay grafts (p = 0.001 for collagen and p = 0.01 for elastin) and tubularized ABM (10%, p = 0.003 and 0.05, respectively). At the type 2 injury site, a dense circumferential fibrosis developed after all repairs. Only minimal ventral fibrosis presented in the type 1 injury repair. The intensity of chronic inflammation and fibrosis was greatest when collagen was used for the urethral repair. In the elastin urethral repairs the urethral diameter decreased significantly for the tubed repair compared to the patch onlay (p = 0.02). Conclusion: Urethral injury repair using elastin and collagen biomaterials is feasible in the rabbit model. The results of onlay urethroplasty using the elastin and collagen patches are significantly superior to those using the elastin and collagen tubed conduits. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Photocrosslinkable hydrogel for myocyte cell culture and injection
Authors: Yeo Yoon , Geng Wenliang , Ito Taichi , Kohane Daniel S. , Burdick Jason A. , Radisic Milica 
Published: September 2006

AbstractConventional treatment options for myocardial infarction are limited by the inability of mature myocardium to regenerate after injury. Although functional improvements after injection of cells and growth factors have been demonstrated, the clinical utility of this procedure has been hampered by poor cell localization, low survival, and rapid clearance of injected growth factors. The main objective of this study was to evaluate the applicability of a hydrogel, based on photocrosslinkable chitosan and acryloyl‐poly(ethylene glycol)‐RGDS (Az‐chitosan/Acr‐PEG‐RGD) for myocyte cell culture and myocardial injection. Chitosan was modified with photoreactive azidobenzoic acid and Acr‐PEG‐RGD was synthesized by reacting YRGDS with an equimolar amount of acryloyl‐PEG‐N‐hydroxysuccinimide. For injection and encapsulation each polymer was dissolved in Di‐H2O (pH 6.4), the solutions were mixed and crosslinked by UV application (4 mW/cm2). C2C12 myoblasts proliferated and differentiated on hydrogels containing 5 mM RGD but not on the pure photocrosslinked chitosan. In vitro, the crosslinked hydrogels retained 80% of encapsulated VEGF for 24 days. Live/dead staining of neonatal rat cardiomyocytes encapsulated into Az‐chitosan/Acr‐PEG‐RGD hydrogels indicated high cell viability upon UV crosslinking. Ex vivo, we localized the hydrogel on the surface and in the ventricle wall of an adult rat heart by brief (2 min) UV light application. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006