bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite element modelling of compressive mechanical behaviour of high and low density polymeric foams
Authors: Alvarez P. , Mendizabal A. , Petite M.M. , Rodríguez‐Pérez M.A. , Echeverria A. 
Published: March 2009

AbstractIn this work, different methodologies were studied by means of finite element modelling (FEM) with the aim of predicting the mechanical behaviour of high and low relative density (ρr) polymeric foams. Virtual structures which resemble the real ones were created by various computer‐based tools. These tools were employed to make up both “unit cells” and random structural units so‐called “Representative Volume Elements” (RVE). Low ρr foams are usually modelled as regular (tetrakaidecahedron) and irregular (Voronoi tessellations) 3D structures made of structural elements (beams and shells). These types of finite elements are only applicable if the ratio between longitudinal and axial dimensions exceeds a certain value and therefore, there is a practical relative density limit above which these elements are not suitable. Alternatively, virtual low ρr foams were created by means of cellular automata which allow a close control of bubble growth and final cell character and do not show the previous limitation. Additionally, virtual high ρr structures (ρr > 0.5) consisting of isolated bubbles or cells were created by random incorporation of cell sets whose size distributions adjust to experimentally measured ones. A random sequential adsorption algorithm (RSA) which accurately controls final thickness of ligaments between cells was programmed for this purpose. FEM results of this kind of virtual foams are compared with experimentally tested mechanical properties. Moreover, impact of structural parameters (mean cell size) on elastic modulus and compressive collapse stress is critically assessed.
Hollow sphere structures: a study of mechanical behaviour using numerical simulation
Authors: Oliveira B. F. , da Cunda L. A. B. , Öchsner A. , Creus G. J. 
Published: March 2009

AbstractOne way to obtain a cellular metal with a uniform microstructure is to employ hollow metallic spheres welded or bonded. Such materials are known as MHSS (Metallic Hollow Sphere Structures). Cellular metals can be applied as crash absorbers that act in compression and can be severely deformed. Thus, finite deformations and damage must be considered in the numerical simulation. In this work, the numerical simulation via finite elements is employed to study the mechanical behaviour of MHSS. The study employs the concept of RVE (Representative Volume Elements) where a cell is used to represent the whole material behaviour. Numerical results are compared with experimental data.
A study on the fatigue behaviour of electro‐plated NiCo thin film for probe tip applications
Authors: Park J.‐H. , Chun Y.‐B. , Kim Y.‐J. , Huh Y.‐H. , Lee H.‐J. 
Published: March 2009

AbstractIn this study, fatigue tests were performed for NiCo alloy which is commonly used in probe tips of test machines of semiconductors. The smooth specimens were fabricated by MEMS process including electro‐plating process on a single‐side polished 6 inches (100) silicon wafer. The NiCo thin film consists of about 66.2 % Ni and 33.8 % Co. The specimen is 2000 μm long, 9 μm thick and 100 μm wide. The tests were performed using a novel test procedure, a structure of the specimen is easy to manipulate, align and grip a thin‐film and a test machine proposed by the authors. The closed‐loop feedback control of the magnetic‐electric actuator allowed load‐controlled and high cycle fatigue tests with 5 Hz frequency, in ambient environment and with a stress ratio of R = 0.1. The fatigue strength coefficient and exponent were 1324 MPa and ‐0.0558, respectively. In a fatigue test of thin film, it is difficult to perform the fatigue test at R = ‐1. However, the result of the fatigue test at R = ‐1 should be required when fatigue life prediction is performed under variable loading. Therefore, in this study, the modified Goodman method, Gerber method and Soderberg method were considered to investigate which method is most reasonable when mean stress is considered.
Experimental characterization of composite and smart patching repaired edge cracked plate in charpy impact
Authors: Khalili S. M. R. , Nooramin A. S. , Shiravi M. 
Published: March 2009

AbstractIn this study, edge‐cracked steel plates repaired on two‐sides with composite as well as smart composite patches were investigated experimentally for their response to Charpy impact test. Woven glass and Kevlar fibres were used for composite patches. Each patch was made by two layers. The crack length was kept constant for all the specimens. The types of patches were selected according to different combination of glass and/or Kevlar fibres for maximum energy absorption. Kevlar fibre composite patches showed better energy absorption. This configuration was then reinforced by shape memory alloy (SMA) wires. For fabrication of smart patches, nickel‐titanium (Ni‐Ti) wires were embedded in the Kevlar fibre composites. The SMA wires in the patches were used in 3 different temperatures or pre‐stress states. The patch of Kevlar fibre reinforced by Ni‐Ti wires treated by combination of pre‐load and temperature states showed better results than all other smart patches in Charpy impact test.
Residual stress analysis of an autofrettaged compound cylinder under machining process
Authors: Lee E.‐Y. , Lee Y.‐S. , Kim J.‐H. , Cha K.‐U. , Hong S.‐K. 
Published: March 2009

AbstractThe autofrettage process is used to manufacture pressure vessels and cylinders that can withstand high internal pressure. A multi‐layered cylinder was assembled by a shrink fit. Autofrettaged compound cylinder can resist higher internal pressure than a thick cylinder having the same dimension and extend its life time. Inner and outer surfaces of the autofrettaged compound cylinder have to be manufactured into exact dimensions. The distribution of residual stress can change after the machining process. The machining procedure of inner and outer surfaces also affects the distribution of residual stress as a function of the machining procedure. In this study, the distribution of residual stresses of an autofrettaged compound cylinder as machining procedure was investigated using analytical and numerical analyses.
Optimization of Artificial Hip Joint Parameters
Authors: Darwish S.M. , Al‐Samhan A.M. 
Published: March 2009

AbstractThe hip is a ball and socket joint designed to bear the body mass as well as for facilitating the movement in many directions. Hip replacement is an operation to replace a natural hip joint with an artificial one. The aim of the present work is to conduct a parametric study that comprises the parameters affecting the strength of hip‐joint cement fixation (offset distance and ball diameter), in order to come‐up with the best combination for maximum strength. The results lead to recommending offset distance (3–6 mm) and ball sizes (34 and 50 mm) for maximum cement strength.
Targeted disruption of Bcl‐xL in mouse keratinocytes inhibits both UVB‐ and chemically induced skin carcinogenesis
Authors: Kim Dae Joon , Kataoka Ken , Sano Shigetoshi , Connolly Kevin , Kiguchi Kaoru , DiGiovanni John 
Published: March 2009

AbstractBcl‐xL is one of several antiapoptotic proteins regulated by signal transducer and activator of transcription 3 (Stat3). We have recently shown that Stat3 is required for chemically induced and ultraviolet B (UVB)‐induced skin carcinogenesis. In this study, the functional role of Bcl‐xL in skin carcinogenesis was investigated using skin‐specific Bcl‐xL‐deficient mice. In this model, Bcl‐xL expression is disrupted in the basal compartment of mouse epidermis using the bovine keratin 5 (K5) promoter to drive expression of Cre recombinase (K5.Cre × Bcl‐x mice). A significant increase in apoptosis induced by either UVB irradiation or 7,12‐dimethylbenz[a]anthracene (DMBA) treatment was observed in the epidermis of Bcl‐xL‐deficient mice. Furthermore, an increase in apoptotic cells was noted in hair follicle keratinocytes, including those located in the bulge region. Cell proliferation was not affected by Bcl‐xL deficiency following exposure to either UVB or 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). Bcl‐xL‐deficient mice were more resistant than wild‐type controls to skin tumor development with delayed onset and reduced number of tumors using either UVB or the DMBA/TPA two‐stage regimen. Moreover, Bcl‐2, Mcl‐1, and survivin protein levels were increased in the epidermis of Bcl‐xL‐deficient mice in the absence of stimuli. Furthermore, levels of these antiapoptotic proteins were also high in skin tumors from Bcl‐xL‐deficient mice that developed in response to either UVB or two‐stage carcinogenesis protocols. Collectively, these studies demonstrate that Bcl‐xL plays a role early in skin carcinogenesis through its anti‐apoptotic functions to enhance survival of keratinocytes, including bulge region keratinocyte stem cells, following DNA damage. © 2009 Wiley‐Liss, Inc.
Repair of electrically injured median nerve with the aid of somatosensory evoked potential
Authors: Gu Bin , Xie Feng , Jiang Hao , Shen Guoxiong , Li Qingfeng 
Published: March 2009

AbstractIn repair of the high voltage electrical injuries of peripheral nerve, selection of the proper plane for nerve coaptation after debridement is important since the electrical current is inclined to pass through the nerve trunks due to the lower electric resistance. In this report, we present our experience on use of the somatosensory evoked potentials (SSEP) test to assist determination of range of the injured nerve debridement in the electrical injured nerve. From January 1997 to December 2007, 30 patients with the high voltage electrical injury in the wrist, having defect of median nerve, were treated with nerve grafting. In 18 patients, the nerve resection plane was selected with the assistance of SSEP. In 12 patients, the nerve resection plane was determined by the traditional gross examination. The average lengths of nerve defect after debridement were 10.4 cm in the procedure with SSEP assistance and 4.01 cm in the traditional procedure. The finger motion was reconstructed by the tendon graft connecting the proximal forearm muscle and the distal tendon of flexor disitorum profundus. In following up, the two‐point discrimination of finger was examined. The grade of finger sensory recovery was found improved in the patients who underwent the nerve repair with SSEP assistance than that in the patients underwent treatment with the traditional method. The results suggested that aggressive debridement is recommended for the high with voltage electrical nerve injury. SSEP could be a valuable tool for determination of the range of nerve debridement. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Effects of acetylo‐L‐carnitine in end‐to‐side neurorrhaphy: A pilot study
Authors: Kostopoulos Vasileios K. , Davis Christin L. , Terzis Julia K. 
Published: March 2009

AbstractPurpose: End‐to‐side (ETS) nerve repair allows for target‐muscle reinnervation, with simultaneous preservation of donor‐nerve function. Acetyl‐L‐carnitine (ALCAR) was shown to enhance axonal sprouting in early regeneration following transection and repair of the sciatic nerve in rodents. The purpose of this article was to determine the ability of ALCAR to enhance axonal regeneration in an ETS rodent model. Method: The right musculocutaneous nerve in 16 adult male Sprague‐Dawley rats was transected to induce biceps muscle paralysis. The distal stump was then coapted by ETS neurorrhaphy through a perineurial window to the ipsilateral median nerve. Experimental groups received ALCAR for 1, 2, 3, and 4 weeks whereas controls received placebo. Results: Weekly postoperative behavioral evaluations revealed increased functional return over control but the difference was not significant. Potentials from biceps were recorded from the third postoperative week in the experimental group and from the fourth week in the control group. Histomorphometric evaluations revealed higher musculocutaneous nerve axon counts, higher myelin thickness in the fourth postoperative week, and differences in the appearance and the number of motor‐end‐plates in the biceps in experimental versus control group. Conclusion: Intraperitoneal administration of ALCAR can expedite biceps muscle recovery in an ETS model by increasing the rate of axonal regeneration. Despite the morphological changes, no behavioral changes were noted and further studies are needed to confirm clinical efficacy of ALCAR for potential use in the development of therapeutic protocols. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Protein‐free ligand screening: simplification of chiral chromatographic development via novel adaptation of NMR screening methodologies
Authors: Thompson Melissa R. , McKenzie David R. , Likos John J. , Gard Janice K. 
Published: March 2009

AbstractWe demonstrate here a promising NMR method that provides evidence for chiral compound selector interaction as a first‐pass screening method. A novel adaptation of commonly used protein‐based screening technologies, this approach relies upon ligand‐to‐stationary phase interaction wherein the stationary phase is tethered to sepharose beads. At only minutes per experiment, this methodology significantly reduces the time required for chiral separation methodology development and complements currently available chromatographic purity technologies.Copyright © 2009 John Wiley & Sons, Ltd.
Metabonomic identification of novel biomarkers in doxorubicin cardiotoxicity and protective effect of the natural antioxidant oleuropein
Authors: Andreadou Ioanna , Papaefthimiou Maria , Zira Athina , Constantinou Maria , Sigala Fragiska , Skaltsounis Alexios‐Leandros , Tsantili‐Kakoulidou Anna , Iliodromitis Efstathios K. , Kremastinos Dimitrios T. , Mikros Emmanuel 
Published: March 2009

AbstractDoxorubicin (DXR) is a commonly used antineoplastic agent; however, its use is limited due to cardiotoxicity. Oxidative stress and consequent alterations of cardiac energetics are involved in the development of DXR toxicity. Oleuropein (Oleu) is a phenolic antioxidant, present in olive tree, reported to confer protection against DXR cardiotoxicity. In this study, NMR based‐metabonomics was applied to characterize the metabolic profile of the acute DXR cardiotoxicity in rats and to evaluate the metabolic alterations conferred by co‐treatment with Oleu. Wistar rats were divided into six groups and treated as follows: control group with a single injection of 2 mL normal saline intraperitoneally (i.p.), DXR group with a single dose of 20 mg/kg, i.p and DXR plus Oleu groups with 20mg/kg DXR i.p., and 100 or 200 mg/kg/BW of Oleu i.p. for 5 or 3 consecutive days starting either 2 days before or on the day of DXR administration. Hearts were excised 72 h after DXR treatment and1H‐NMR spectra of aqueous myocardium extracts were recorded. Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS‐DA) revealed differences in the metabolic profile between control and DXR attributed to several metabolites. A number of them were quantified by integration of the NMR spectra. Myocardial levels of acetate and succinate were increased in DXR compared to controls, while branched amino acids were decreased. These results correlate with nonenzymatic conversion of pyruvate to acetate and ofα‐ketoglutarate to succinate by DXR free radicals. Oleu completely restored the changes of metabolites to the normal levels. Acetate and succinate constitute novel biomarkers related to DXR, and Oleu treatment aids the compensation of distressed energy metabolic pathways. Copyright © 2009 John Wiley & Sons, Ltd.
Combined equivalent charge formulations and fast wavelet Galerkin BEM for 3‐D electrostatic analysis
Authors: Xiao Jinyou , Tausch Johannes , Cao Yanchuang , Wen Lihua 
Published: March 2009

AbstractWe describe a new equivalent charge formulation (ECF), i.e. the combined ECF (CECF), for electrostatic analysis of structures consisting of conductors and dielectrics. The CECF uses a weighted combination of the single‐ and the adjoint double‐layer operators to account for the potential on the conductor–dielectric surface and is found to have better conditioning than the standard ECF. A perturbation approach is presented to insure that the capacitances are computed accurately even when the permittivity ratios of the dielectrics are vary large. Unlike the original perturbation approach, this new approach uses only one system matrix with different right‐hand sides.A wavelet Galerkin boundary element method (WGBEM) for solving the ECF and CECF is developed based on the new variable‐order WGBEM introduced in (J. Numer. Math. 2004; 12(3):233–254). The wavelets are directly constructed on the usual boundary element triangulation. This enables the proposed WGBEM to solve electrostatic problems in complicated geometries, unstructured meshes and comparatively coarse discretizations. The quasi‐vanishing moment wavelets introduced in (Comput. Methods Appl. Mech. Engng 2008; 197:4000–4006) are used to further reduce the memory and CPU time requirements.Several numerical examples show that the proposed CECF converges faster than the ECF, and that the WGBEM, using both the ECF and CECF, has almost linear complexity in solving large‐scale 3‐D electrostatic problems. Moreover, since the truncated non‐standard form is computed once and then stored, the WGBEM is very suitable for solving problems with multiple right‐hand sides, like the perturbation approach in this paper. Copyright © 2009 John Wiley & Sons, Ltd.
Finite strain, finite rotation quadratic tetrahedral element for the combined finite–discrete element method
Authors: Xiang Jiansheng , Munjiza Antonio , Latham John‐Paul 
Published: March 2009

AbstractIn the past, the combined finite–discrete element was mostly based on linear tetrahedral finite elements. Locking problems associated with this element can seriously degrade the accuracy of their simulations. In this work an efficient ten‐noded quadratic element is developed in a format suitable for the combined finite–discrete element method (FEMDEM). The so‐called F‐bar approach is used to relax volumetric locking and an explicit finite element analysis is employed. A thorough validation of the numerical method is presented including five static and four dynamic examples with different loading, boundary conditions, and materials. The advantages of the new higher‐order tetrahedral element are illustrated when brought together with contact detection and contact interaction capability within a new fully 3D FEMDEM formulation. An application comparing stresses generated within two drop experiments involving different unit specimens called Vcross and VRcross is shown. The Vcross and VRcross units of ∼3.5 × 104kg show very different stress generation implying different survivability upon collision with a deformable floor. The test case shows the FEMDEM method has the capability to tackle the dynamics of complex‐shaped geometries and massive multi‐body granular systems typical of concrete armour and rock armour layers. Copyright © 2009 John Wiley & Sons, Ltd.
Lagrangian mechanics and variational integrators on two‐spheres
Authors: Lee Taeyoung , Leok Melvin , McClamroch N. Harris 
Published: March 2009

AbstractEuler–Lagrange equations and variational integrators are developed for Lagrangian mechanical systems evolving on a product of two‐spheres. The geometric structure of a product of two‐spheres is carefully considered in order to obtain global equations of motion. Both continuous equations of motion and variational integrators completely avoid the singularities and complexities introduced by local parameterizations or explicit constraints. We derive global expressions for the Euler–Lagrange equations on two‐spheres, which are more compact than existing equations written in terms of angles. Since the variational integrators are derived from Hamilton's principle, they preserve the geometric features of the dynamics such as symplecticity, momentum maps, or total energy, as well as the structure of the configuration manifold. Computational properties of the variational integrators are illustrated for several mechanical systems. In addition, Lie group variational integrators can be used to integrate Lagrangian flows on more general homogeneous spaces. This is achieved by lifting the discrete Hamilton's principle on homogeneous spaces to a discrete variational principle on the Lie group that is constrained by a discrete connection. Copyright © 2009 John Wiley & Sons, Ltd.
Small polyhedron reconnection for mesh improvement and its implementation based on advancing front technique
Authors: Liu Jianfei , Chen Y. Q. , Sun S. L. 
Published: March 2009

AbstractLocal transformation, or topological reconnection, is one of the effective procedures for mesh improvement method, especially for three‐dimensional tetrahedral mesh. The most frequently used local transformations for tetrahedral mesh are so‐called elementary flips, such as 2‐3 flip, 3‐2 flip, 2‐2 flip, and 4‐4 flip. Owing to the reason that these basic transformations simply make a selection from several possible configurations within a relatively small region, the improvement of mesh quality is confined. In order to further improve the quality of mesh, the authors recently suggested a new local transformation operation, small polyhedron reconnection (SPR) operation, which seeks for the optimal tetrahedralization of a polyhedron with a certain number of nodes and faces (typically composed of 20–40 tetrahedral elements).This paper is an implementation of the suggested method. The whole process to improve the mesh quality by SPR operation is presented; in addition, some strategies, similar to those used in advancing front technique, are introduced to speed up the operation. The numerical experiment shows that SPR operation is quite effective in mesh improvement and more suitable than elementary flips when combined with smoothing approach. The operation can be applied to practical problems, gaining high mesh quality with acceptable cost for computational time. Copyright © 2009 John Wiley & Sons, Ltd.
Congenital glioblastoma
Authors: Milano G.M. , Cerri C. , Ferruzzi V. , Capolsini I. , Mastrodicasa E. , Genitori L. , Aversa F. 
Published: March 2009

AbstractWe describe the case a 2‐day‐old female with congenital glioblastoma. Total resection was followed by adjuvant and high dose chemotherapy, as indicated by the current Italian infant protocol. The child is alive and well 18 months after diagnosis. A review of 67 selected congenital brain tumors showed the mortality rate was 82%. Even though the majority of patients had glioblastoma, only 5/67 had received adjuvant therapy. To ensure optimal outcomes, we recommend total or subtotal surgical resection, followed by adjuvant and high dose chemotherapy. Given the lack specific protocols for congenital brain tumors an international consensus seems to be needed, starting with congenital glioblastoma. Pediatr Blood Cancer 2009;53:124–126. © 2009 Wiley‐Liss, Inc.
Negative correlation between cerebrospinal fluid tau protein and cognitive functioning in children with acute lymphoblastic leukemia
Authors: Protas Piotr T. , Muszynska‐Roslan Katarzyna , Holownia Adam , Grabowska Aleksandra , Wielgat Przemyslaw , Krawczuk‐Rybak Maryna , Braszko Jan J. 
Published: March 2009

AbstractThe aim of the study was to assess whether cerebrospinal fluid tau protein is associated with cognitive changes in children with acute lymphoblastic leukemia (ALL). Examination of 38 ALL patients revealed a statistically significant increase in tau protein on treatment day 59 and at two points during consolidation phase. Cognitive functioning was examined in 19 patients at an average of 3.7 years after diagnosis. The level of tau at the initiation of maintenance therapy was negatively correlated with verbal abilities measured on an intellectual scale. The study suggests that standard ALL treatment may cause a decline in cognitive functioning. Pediatr Blood Cancer 2009;53:105–108. © 2009 Wiley‐Liss, Inc.