bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of synergistic reinforcement and absorbable fiber strength on hydroxyapatite bone cement
Authors: Zhang Yu , Xu Hockin H.K. 
Published: September 2005

AbstractApproximately a million bone grafts are performed each year in the United States, and this number is expected to increase rapidly as the population ages. Calcium phosphate cement (CPC) can intimately adapt to the bone cavity and harden to form resorbable hydroxyapatite with excellent osteoconductivity and bone‐replacement capability. The objective of this study was to develop a strong CPC using synergistic reinforcement via suture fibers and chitosan, and to determine the fiber strength–CPC composite strength relationship. Biopolymer chitosan and cut suture filaments were randomly mixed into CPC. Both suture filaments and composite were immersed in a physiological solution. After 1‐day immersion, cement flexural strengths (mean ± SD;n= 6) were: (2.7 ± 0.8) MPa for CPC control; (11.2 ± 1.0) MPa for CPC–chitosan; (17.7 ± 4.4) MPa for CPC–fiber composite; and (40.5 ± 5.8) MPa for CPC–chitosan–fiber composite. They are significantly different from each other (Tukey's at 0.95). The strength increase from chitosan and fiber together in CPC was much more than that from either fiber or chitosan alone. The composite strength became (9.8 ± 0.6) MPa at 35‐day immersion and (4.2 ± 0.7) MPa at 119 days, comparable to reported strengths for sintered porous hydroxyapatite implants and cancellous bone. After suture fiber dissolution, long macropore channels were formed in CPC suitable for cell migration and tissue ingrowth. A semiempirical relationship between suture fiber strengthSFand composite strengthSCwere obtained:SC= 14.1 + 0.047SF, withR= 0.92. In summary, this study achieved substantial synergistic effects by combining random suture filaments and chitosan in CPC. This may help extend the use of the moldable,in situhardening hydroxyapatite to moderate stress‐bearing orthopedic applications. The long macropore channels in CPC should be advantageous for cell infiltration and bone ingrowth than conventional random pores and spherical pores. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Functional activity of insulinoma cells (INS‐1E) and pancreatic islets cultured in agarose cryogel sponges
Authors: Bloch K. , Lozinsky V. I. , Galaev I. Yu. , Yavriyanz K. , Vorobeychik M. , Azarov D. , Damshkaln L. G. , Mattiasson B. , Vardi P. 
Published: September 2005

AbstractHere, we describe the preparation, structure, and properties of cryogel sponges, which represent a new type of macroporous biomaterial for tissue engineering. Cryogels were produced through freeze–thawing techniques, either from agarose alone or from agarose with grafted gelatin. The aim of this study was to evaluate agarose cryogel sponges as scaffolds for culturing both isolated pancreatic islets and insulinoma cells (INS‐1E). In order to evaluate the effect of cell entrapment in artificial scaffolds, cell function reflected by insulin secretion and content was studied in cells cultivated for a 2‐week period either in culture plastic plates or in cryogel sponge disks. Our results show that tumor‐derived INS‐1E cells grown either on plastic or on cryogels do not differ in their proliferation, morphology, insulin release, and intracellular insulin content. However, isolated pancreatic islets cultivated on cryogels sponge show 15‐fold higher basal insulin secretion at 3.0 mM glucose than islets cultivated on plastic plates and fail to respond to stimulation with 16.7 mM glucose. In addition, these islets have about 2‐fold lower insulin content compared to those grown in plastic plates. It is possible that the cell dysfunction noted in these in vitro experiments is due to the effect of the limited oxygen supply to the islets cultivated in cryogel sponge. Further in vivo studies are needed to clarify the nature of such an observation since according to previous reports, agarose and gelatin induce new vessel formation supporting enhanced oxygen supply. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Evaluations of blood compatibility via protein adsorption treatment of the vascular scaffold surfaces fabricated with polylactide and surface‐modified expanded polytetrafluoroethylene for tissue engineering applications
Authors: Choi Yoon Jeong , Choung Sung Kwang , Hong Choong Man , Shin In Soo , Park Sue Nie , Hong Seung Hwa , Park Han Ki , Park Young Hwan , Son Youngsook , Noh Insup 
Published: September 2005

AbstractBlood compatibility was evaluated by short‐term in vitro blood perfusion on candidate vascular scaffold surfaces of a biodegradable, porous polylactide scaffold and a chemically surface‐modified expanded polytetrafluoroethylene (ePTFE) over a clinical ePTFE, by measuring blood cell adhesion either directly or after adsorption treatment with albumin and fibrinogen. The results indicated that the extent of blood cell adhesion was affected by scaffold surface properties and pre‐adsorption of proteins such as fibrinogen and albumin. Surface morphologies and porosity of the scaffolds were characterized by scanning electron microscopy and porosimetry, and the amount of fibrinogen and albumin adsorbed on the scaffolds was measured and verified by employing radiolabeled C14 albumin and I125 fibrinogen by a scintillation counter and a gamma counter, respectively. Even though treatment of fibrinogen adsorption on the samples in advance led to higher induction of blood cell adhesion than those with no fibrinogen adsorption, the polylactide scaffold surface itself induced highest amount of the adhered blood cells in this study judged by analyses of their surface area. These results would be employed as guidance in determining a choice of the implant methods, in vitro versus in vivo tissue engineering, of the novel chemically modified ePTFE and the biodegradable polylactide scaffolds. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Solution‐mediated effect of bioactive glass in poly (lactic‐co‐glycolic acid)–bioactive glass composites on osteogenesis of marrow stromal cells
Authors: Yao Jun , Radin Shula , Reilly Gwendolen , Leboy Phoebe S. , Ducheyne Paul 
Published: September 2005

AbstractA previous study demonstrated that the incorporation of bioactive glass (BG) into poly (lactic‐co‐glycolic acid) (PLGA) can promote the osteoblastic differentiation of marrow stromal cells (MSCs) on PLGA by promoting the formation of a calcium–phosphate‐rich layer on its surface. To further understand the mechanisms underlying the osteogenic effect of PLGA‐BG composite scaffolds, whether solution‐mediated factors derived from composite scaffolds/hybrids can promote osteogenesis of marrow stromal cells was tested. The dissolution product from PLGA‐30%BG scaffold stimulated osteogenesis of MSCs, as was confirmed by increased mRNA expression of osteoblastic markers such as osteocalcin (OCN), alkaline phosphatase (ALP), and bone sialoprotein (BSP). The three‐dimensional structure of the scaffolds may contribute to the production of cell‐derived factors that promoted distant MSC differentiation. Thus PLGA‐BG composites demonstrate significant potential as a bone‐replacement material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Self‐organized nanotubular oxide layers on Ti‐6Al‐7Nb and Ti‐6Al‐4V formed by anodization in NH4F solutions
Authors: Macak Jan M. , Tsuchiya Hiroaki , Taveira Luciano , Ghicov Andrei , Schmuki Patrik 
Published: September 2005

AbstractThe present work reports the fabrication of self‐organized porous oxide‐nanotube layers on the biomedical titanium alloys Ti‐6Al‐7Nb and Ti‐6Al‐4V by a simple electrochemical treatment. These two‐phase alloys were anodized in 1M (NH4)2SO4 electrolytes containing 0.5 wt % of NH4F. The results show that under specific anodization conditions self‐organized porous oxide structures can be grown on the alloy surface. SEM images revealed that the porous layers consist of arrays of single nanotubes with a diameter of 100 nm and a spacing of 150 nm. For the V‐containing alloy enhanced etching of the β phase is observed, leading to selective dissolution and an inhomogeneous pore formation. For the Nb‐containing alloy an almost ideal coverage of both phases is obtained. According to XPS measurements the tubes are a mixed oxide with an almost stoichiometric oxide composition, and can be grown to thicknesses of several hundreds of nanometers. These findings represent a simple surface treatment for Ti alloys that has high potential for biomedical applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Spatially controlled co‐culture of neurons and glial cells
Authors: Yang In Hong , Co Carlos C. , Ho Chia‐Chi 
Published: September 2005

AbstractThe ability to create and maintain neuron and glial cell co‐cultures is important for neuronal regeneration as well as for fundamental studies on neuron and glial cell interactions. We demonstrate here a method for spatially controlling the arrangement of neurons and glial cells. Line patterns of cell resistant, poly(oligoethyleneglycol methacrylate‐co‐methacrylic acid), was microcontact printed on various substrates to spatially control the attachment of neurons. Neuron‐like cells, PC12 and SH‐SY5Y cells, were confined within the unprinted line patterns and extended neurites along the line patterns. Subsequent attachment of glial cells was accomplished by converting the originally cell‐resistant line patterns of poly(oligoethyleneglycol methacrylate‐co‐methacrylic acid) to cell adhesive by electrostatic adsorption of cationic poly‐lysine, chitosan, or poly(ethyleneimine). This method for creating patterned co‐cultures of neuron and glial cells provides a useful tool for investigating neuron–glial cell interactions and has potential applications in the repair or regeneration of nervous systems. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
The role of bivalent metals in hydroxyapatite structures as revealed by molecular modeling with the HyperChem software
Authors: Gutowska Izabela , Machoy Zygmunt , Machaliński Bogusław 
Published: September 2005

AbstractHydroxyapatite, the major component of bone, demonstrates significant reactivity with metals. Knowledge of spatial structure and energy data of the molecule helps understand the binding of metals by hydroxyapatite and elucidate the chemical and physical properties of such complexes. We used HyperChem software (Hypercube Inc.) to analyze the structure of hydroxyapatite when the central calcium atom is replaced by one of the metal ions (Mg, Cu, Zn, Fe, Cr, Mn) marked by us in bone. Our results show that hetero‐ionic exchange affects composition and leads to deformation of hydroxyapatite crystals. Replacement was accompanied by changes in bond lengths between oxygen and calcium atoms in the hydroxyapatite molecule and by displacement of groups of atoms surrounding the central calcium atom. The use of molecular modeling as a computational tool enabled a preliminary and theoretical understanding of chemical structure without the need for laboratory tests. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Fluorinated diamond‐like carbon as antithrombogenic coating for blood‐contacting devices
Authors: Hasebe Terumitsu , Shimada Atsushi , Suzuki Tetsuya , Matsuoka Yoshiaki , Saito Toshiya , Yohena Satoshi , Kamijo Aki , Shiraga Nobuyuki , Higuchi Mutsumi , Kimura Kanako , Yoshimura Hirokuni , Kuribayashi Sachio 
Published: September 2005

AbstractDiamond‐like carbon (DLC) is being considered for widespread clinical use as a surface coating for cardiovascular devices. We synthesized fluorinated DLC (F‐DLC) coatings in order to create a more hydrophobic surface with improved antithrombogenicity and flexibility when compared with conventional DLC coatings by combining the inertness of DLC films with the advantage of fluorination. The purpose of this study was to evaluate the in vitro hemocompatibility and in vivo biocompatibility of the F‐DLC coating for medical devices. The in vitro whole blood model confirmed that platelet loss was lower in the F‐DLC group than in the noncoated group (SUS316L), which suggests the adhesion of a smaller number of platelets to F‐DLC‐coated materials. Furthermore, the biomarkers of mechanically induced platelet activation (beta‐thromboglobulin) and activated coagulation (thrombin‐antithrombin‐three complex) were markedly reduced in the F‐DLC‐coated group. In vivo rat implant model studies revealed no excessive local and systemic inflammatory responses in the F‐DLC group. The thickness of the fibrous tissue capsule surrounding the F‐DLC‐coated disk was almost equal to that of the noncoated SUS316L disk, which has the favorable biocompatibility for metallic implant materials. F‐DLC coating thus appears to be a promising candidate for use as a coating material in blood‐contacting devices. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Optimization of amino group density on surfaces of titanium dioxide nanoparticles covalently bonded to a silicone substrate for antibacterial and cell adhesion activities
Authors: Okada Masahiro , Yasuda Shoji , Kimura Tsuyoshi , Iwasaki Mitsunobu , Ito Seishiro , Kishida Akio , Furuzono Tsutomu 
Published: September 2005

AbstractA composite consisting of titanium dioxide (TiO2) particle, the surface of which was modified with amino groups, and a silicone substrate through covalent bonding at their interface was developed, and antibacterial and cell adhesion activities of the composite were evaluated. The density of the amino groups on the TiO2 particle surface was controlled by the reaction time of the modification reaction. The degradation rate of CH3CHO in the presence of the TiO2 particles under UV irradiation decreased with an increase in the amino group density on the TiO2 surface. On the other hand, the number of L929 cells adhering on the TiO2/silicone composite increased with an increase in the amino group density. From the above two results, the optimum density of amino groups for both photoreactivity and cell adhesiveness was estimated to be 2.0–4.0 molecules/nm2. The optimum amino group‐modified TiO2/silicone composite sheet (amino group density, 3.0 molecules/nm2) showed an effective antibacterial activity for Escherichia coli bacteria under UV irradiation. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Gender‐specific differences in electromyographic changes and perceived pain induced by experimental muscle pain during sustained contractions of the upper trapezius muscle
Authors: Ge Hong‐You , Arendt‐Nielsen Lars , Farina Dario , Madeleine Pascal 
Published: September 2005

AbstractThe aim of the study was to investigate gender‐specific differences in the pain‐induced alterations of muscle activity during sustained contractions of the upper trapezius muscle. Surface electromyographic (EMG) signals were recorded bilaterally from the upper trapezius muscles of healthy volunteers (10 men and 9 women). The subjects held the arms at 90° abduction for 5 s (short contraction) and 3 min (sustained contraction). These contractions were performed before, during, and after injection of 0.5 ml of hypertonic saline (5.8%) bilaterally in the upper trapezius muscles. Injection of isotonic saline (0.9%) served as control. The root mean square (RMS) and mean power frequency (MPF) were computed from the EMG signals and normalized to the values obtained during maximal voluntary contractions. In the short contractions, injection of hypertonic saline, but not isotonic saline, induced a less pronounced decrease in RMS in women than men, and a significant decrease in MPF in men but not women. In the sustained contractions, RMS slope increased and MPF slope decreased (less negative) with muscle pain in men but not women. It was concluded that the pain‐induced changes in motor control strategies during sustained contractions differ in men and women, which may partly explain gender differences in the incidence of musculoskeletal pain. Muscle Nerve, 2005
Distribution network design: Selection and sizing of congested connections
Authors: Huang Simin , Batta Rajan , Nagi Rakesh 
Published: September 2005

AbstractThis paper focuses on certain types of distribution networks in which commodity flows must go through connections that are subject to congestion. Connections serve as transshipment and/or switching points and are modeled as M/G/1 queues. The goal is to select connections, assign flows to the connections, and size their capacities, simultaneously. The capacities are controlled by both the mean and the variability of service time at each connection. We formulate this problem as a mixed integer nonlinear optimization problem for both the fixed and variable service rate cases. For the fixed service rate case, we prove that the objective function is convex and then develop an outer approximation algorithm. For the variable service rate case, both mean and second moment of service time are decision variables. We establish that the utilization rates at the homogeneous connections are identical for an optimal solution. Based on this key finding, we develop a Lagrangian relaxation algorithm. Numerical experiments are conducted to verify the quality of the solution techniques proposed. The essential contribution of this work is the explicit modeling of connection capacity (through the mean and the variability of service time) using a queueing framework. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
Multiscale modelling of particle debonding in reinforced elastomers subjected to finite deformations
Authors: Matouš Karel , Geubelle Philippe H. 
Published: September 2005

AbstractInterfacial damage nucleation and evolution in reinforced elastomers subjected to finite strains is modelled using the mathematical theory of homogenization based on the asymptotic expansion of unknown variables. The microscale is characterized by a periodic unit cell, which contains particles dispersed in a blend and the particle matrix interface is characterized by a cohesive law. A novel numerical framework based on the perturbed Petrov–Galerkin method for the treatment of nearly incompressible behaviour is employed to solve the resulting boundary value problem on the microscale and the deformation path of a macroscale particle is predefined as in the micro‐history recovery procedure. A fully implicit and efficient finite element formulation, including consistent linearization, is presented. The proposed multiscale framework is capable of predicting the non‐homogeneous micro‐fields and damage nucleation and propagation along the particle matrix interface, as well as the macroscopic response and mechanical properties of the damaged continuum. Examples are considered involving simple unit cells in order to illustrate the multiscale algorithm and demonstrate the complexity of the underlying physical processes. Copyright © 2005 John Wiley & Sons, Ltd.
Use of equivalent mass method for free vibration analyses of a beam carrying multiple two‐dof spring–mass systems with inertia effect of the helical springs considered
Authors: Wu Jia‐Jang 
Published: September 2005

AbstractThis paper investigates the free vibration characteristics of a beam carrying multiple two‐degree‐of‐freedom (two‐dof) spring–mass systems (i.e. the loaded beam). Unlike the existing literature to neglect the inertia effect of the helical springs of each spring–mass system, this paper takes the last inertia effect into consideration. To this end, a technique to replace each two‐dof spring–mass system by a set of rigidly attached equivalent masses is presented, so that the free vibration characteristics of a loaded beam can be predicted from those of the same beam carrying multiple rigidly attached equivalent masses. In which, the equation of motion of the loaded beam is derived analytically by means of the expansion theorem (or the mode superposition method) incorporated with the natural frequencies and the mode shapes of the bare beam (i.e. the beam carrying nothing). In addition, the mass and stiffness matrices including the inertia effect of the helical springs of a two‐dof spring–mass system, required by the conventional finite element method (FEM), are also derived. All the numerical results obtained from the presented equivalent mass method (EMM) are compared with those obtained from FEM and satisfactory agreement is achieved. Because the equivalent masses of each two‐dof spring–mass system are dependent on the magnitudes of its lumped mass, spring constant and spring mass, the presented EMM provides an effective technique for evaluating the overall inertia effect of the two‐dof spring–mass systems attached to the beam. Furthermore, if the total number of two‐dof spring–mass systems attached to the beam is large, then the order of the overall property matrices for the equation of motion of the loaded beam in EMM is much less than that in FEM and the computer storage memory required by the former is also much less than that required by the latter. Copyright © 2005 John Wiley & Sons, Ltd.
Solution of flat crack problems in shear mode
Authors: Chen Y. Z. , Lin X. Y. 
Published: September 2005

AbstractSolution of the flat crack problems in shear mode is presented. The least potential energy principle is used to solve the problems. In the solution a family of the crack opening displacements (COD) with some undermined coefficients is assumed. The strain energy stored in body is expressed in the form of a quadratic form with some undetermined coefficients. In the formulation of the quadratic form, the differential–integral equation for the flat crack problem is used. After using the least potential energy principle, the coefficients in the family of COD can be determined and the crack opening displacements can be evaluated immediately. The stress intensity factors along the crack border can be obtained from the known crack opening displacements. A particular feature of the present method is that no singular integral is involved in computation. Several numerical examples are given with the calculated stress intensity factors along the crack border. Copyright © 2005 John Wiley & Sons, Ltd.
Efficient surface reconstruction from contours based on two‐dimensional Delaunay triangulation
Authors: Wang Desheng , Hassan Oubay , Morgan Kenneth , Weatherill Nigel 
Published: September 2005

AbstractThis paper introduces an efficient method for surface reconstruction from sectional contours. The surface between neighbouring sections is reconstructed based on the consistent utilization of the two‐dimensional constrained Delaunay triangulation. The triangulation is used to extract the parametric domain and to solve the problems associated with correspondence, tiling and branching in a general framework. Natural distance interpolations are performed in order to complete the mapping of the added intermediate points. Surface smoothing and remeshing are conducted to optimize the initial surface triangulations. Several examples are presented to demonstrate the effectiveness and efficiency of the proposed approach. Copyright © 2005 John Wiley & Sons, Ltd.
A high‐level programming‐language implementation of topology optimization applied to steady‐state Navier–Stokes flow
Authors: Olesen Laurits Højgaard , Okkels Fridolin , Bruus Henrik 
Published: September 2005

AbstractWe present a versatile high‐level programming‐language implementation of non‐linear topology optimization. Our implementation is based on the commercial software package FEMLAB, and it allows a wide range of optimization objectives to be dealt with easily. We exemplify our method by studies of steady‐state Navier–Stokes flow problems, thus extending the work by Borrvall and Petersson on topology optimization of fluids in Stokes flow (Int. J. Num. Meth. Fluids 2003; 41:77–107). We analyse the physical aspects of the solutions and how they are affected by different parameters of the optimization algorithm. A complete example of our implementation is included as FEMLAB code in an appendix. Copyright © 2005 John Wiley & Sons, Ltd.