bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interface Behaviour of steel grains reinforcing copper based composite
Authors: Jiyang Zhou , Lijuan Zhou , Klaar H.‐J. , Hong Zhao 
Published: December 2004

AbstractA new type of grain reinforcing cast composite is introduced. The reinforcing component is the coarse steel grain (0.6∼1.0mmϕ) with the matrix of tin bronze. The wearing resistance of this material is 10 times as much as the matrix and regarding the tensile strength, 3 times. In this paper, the interface behaviour between grains and the matrix is emphasised. The results show the formation of an interface layer, caused by the diffusion of Fe and Cu, which strengthens the bonding.
Erratum: Botulinum toxin type a therapy during pregnancy. Mov Disord 2004;19(11):1384–1385
Authors: Newman William J. , Davis Thomas L. , Padaliya Bimal B. , Covington Cassondra D. , Gill Chandler E. , Abramovitch Anna I. , Charles P. David 
Published: December 2004

AbstractThe original article to which this Erratum refers was published in Movement Disorders (2004) 19(11)1384–1385.
Predicted permeability parameters of human ovarian tissue cells to various cryoprotectants and water
Authors: Devireddy Ram V. 
Published: December 2004

AbstractThis study presents a generic numerical model to simulate the coupled solute and solvent transport in human ovarian tissue sections during addition and removal of chemical additives or cryoprotective agents (CPA). The model accounts for the axial and radial diffusion of the solute (CPA) as well as axial convection of the CPA, and a variable vascular surface area (A) during the transport process. In addition, the model also accounts for the radial movement of the solvent (water) into and out of the vascular spaces. Osmotic responses of various cells within an human ovarian tissue section are predicted by the numerical model with three model parameters: permeability of the tissue cell membrane to water (Lp), permeability of the tissue cell membrane to the solute or CPA (ω) and the diffusion coefficient of the solute or CPA in the vascular space (D). By fitting the model results with published experimental data on solute/water concentrations within an human ovarian tissue section, I was able to determine the permeability parameters of ovarian tissue cells in the presence of 1.5M solutions of each of the following: dimethyl sulphoxide (DMSO), propylene glycol (PROH), ethylene glycol (EG), and glycerol (GLY), at two temperatures (4°C and 27°C). Modeling Approach 1: Assuming a constant value of solute diffusivity (D = 1.0 × 10−9 m2/sec), the best fit values of Lp ranged from 0.35 × 10−14 to 1.43 × 10−14 m3/N‐sec while ω ranged from 2.57 × 10−14 to 70.5 × 10−14 mol/N‐sec. Based on these values of Lp and ω, the solute reflection coefficient, σ defined as ${\sigma} = 1-{{{\omega} \bar v_{CPA} } \over {L_P }}$ ranged from 0.9961 to 0.9996. Modeling Approach 2: The relative values of ω and σ from our initial modeling suggest that the embedded ovarian tissue cells are relatively impermeable to all the CPAs investigated (or ω ≈ 0 and σ ≈ 1.0). Consequently the model was modified and used to predict the values of Lp and D assuming ω = 0 and σ = 1.0. The best fit values of Lp ranged from 0.44 × 10−14 to 1.2 × 10−14 m3/N‐sec while D ranged from 0.85 × 10−9 to 2.08 × 10−9 m2/sec. Modeling Approach 3: Finally, the best fit values of D from modeling approach 2 were incorporated into model 1 to re‐predict the values of Lp and ω. It is hoped that the ovarian tissue cell parameters reported here will help to optimize chemical loading and unloading procedures for whole ovarian tissue sections and consequently, tissue cryopreservation procedures. Mol. Reprod. Dev. 70: 333–343, 2005. © 2005 Wiley‐Liss, Inc.
Mouse embryonic stem cells and preimplantation embryos require signaling through the phosphatidylinositol 3‐kinase pathway to suppress apoptosis
Authors: Gross Vera S. , Hess Mailee , Cooper Geoffrey M. 
Published: December 2004

AbstractWhereas most mammalian cells require extracellular signals to suppress apoptosis, preimplantation embryos can survive and develop to the blastocyst stage in defined medium without added serum or growth factors. Since cells of these embryos are capable of undergoing apoptosis, it has been suggested that their lack of dependence upon exogenous growth factors results from the production of endogenous growth factors that suppress apoptosis by an autocrine signaling mechanism. In the present study, we have examined the growth factor requirements and intracellular signaling pathways that suppress apoptosis in both mouse preimplantation embryos and embryonic stem (ES) cells, which are derived from the blastocyst inner cell mass. Cultured ES cells, in contrast to intact embryos, required serum growth factors to prevent apoptosis. Suppression of ES cell apoptosis by serum growth factors required the phosphatidylinositol 3‐kinase (PI 3‐kinase) signaling pathway, since apoptosis was rapidly induced by inhibition of PI 3‐kinase with LY294002. In contrast, inhibition of MEK/ERK signaling with U0126 or of mTOR with rapamycin had no detectable effect on ES cell survival. Thus, like most mammalian cells, the survival of ES cells is mediated by growth factor stimulation of PI 3‐kinase signaling. Treatment with LY294002 (but not with U0126 or rapamycin) similarly induced apoptosis of mouse blastocysts in serum‐free medium, indicating that intact preimplantation embryos are also dependent upon PI 3‐kinase signaling for survival. These results demonstrate that PI 3‐kinase signaling is required to suppress apoptosis of both ES cells and intact preimplantation embryos, consistent with the hypothesis that survival of preimplantation embryos is maintained by endogenous growth factors that stimulate the PI 3‐kinase pathway. Mol. Reprod. Dev. 70: 324–332, 2005. © 2005 Wiley‐Liss, Inc.
Identification and characterization of a novel testicular germ cell‐specific gene Ggnbp1
Authors: Zhou Yu , Zhao Qingguo , Bishop Colin E. , Huang Peitang , Lu Baisong 
Published: December 2004

AbstractA novel gene Ggnbp1 was identified during yeast two‐hybrid screening of gametogenetin protein 1 (GGN1)‐interacting proteins. Ggnbp1 gene was found in mouse, rat, and human genomes but not in sequenced yeast, worms, fly, or fish genomes. Northern blotting analysis revealed that the gene was specifically expressed in the testis but not expressed in the other tissues. In situ hybridization showed that it was testicular germ cell‐specific and was specifically expressed in later primary spermatocytes, meiotic cells, and early round spermatids. Western blotting analysis detected a protein of expected size in and only in the testis. By making membrane and cytosolic fractions of germ cells, we were able to show that GGNBP1 associated with the membrane. The identification and characterization of a novel germ cell‐specific gene Ggnbp1 is the first step toward the defining of the functions of Ggnbp1 in spermatogenesis. Mol. Reprod. Dev. 70: 301–307, 2005. © 2005 Wiley‐Liss, Inc.
Measurement of antepartum depressive symptoms during high‐risk pregnancy
Authors: Maloni Judith A. , Park Seunghee , Anthony Mary K. , Musil Carol M. 
Published: December 2004

AbstractThis methodological study was designed to replicate three previous studies of depressive symptoms, compare assessment of antepartum depressive symptoms among high‐risk pregnant women using three standardized instruments, and evaluate the psychometric properties of the instruments. The sample consisted of 89 high‐risk pregnant women treated with bed rest, of whom 37 remained hospitalized at 4 weeks. Depressive symptoms were measured by the Multiple Affect Adjective Checklist Revised (MAACL‐R) Dysphoria construct, the Profile of Mood States (POMS) Depression scale, and the Center for Epidemiologic Studies Depression Scale (CES‐D) across antepartum hospitalization. Internal consistency, test‐retest reliability, and convergent validity were high. Depressive symptoms were high on admission as measured by all three instruments and significantly decreased across time when measured by the MAACL‐R and POMS. © 2004 Wiley Periodicals, Inc. Res Nurs Health 28:16–26, 2005
About the Lax‐Friedrichs scheme for the numerical approximation of hyperbolic conservation laws
Authors: Breuß Michael 
Published: December 2004

AbstractWe discuss the numerical stability of the classical Lax‐Friedrichs method. The scheme features well‐established properties, especially it is TVD and monotone. However, it turns out that oscillations can occur at data extrema which seems to be in severe contrast to the large numerical diffusion the scheme exhibits. We briefly explain the phenomenon by use of a simple model problem and we give a short theoretical discussion. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a Kurchatov's method of linear interpolation for solving nonlinear equations
Authors: Shakhno S. M. 
Published: December 2004

AbstractWe apply the method of linear interpolation of Kurchatov to solve nonlinear operator equations in Banach spaces. Using the principle of majorants of L. V. Kantorovich, we study the semilocal convergence of method of Kurchatov. Quadratic order of convergence of this method is determined. A priori and a posteriori estimations of method's error are received. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling Meshfree Methods and FEM for the Solution of the Incompressible Navier‐Stokes Equations
Authors: Fries Thomas‐Peter , Matthies Hermann G. 
Published: December 2004

AbstractMeshfree Moving Least Squares and meshbased Finite Element shape functions are coupled in order to combine the advantages of each method. Meshfree methods are used in small parts of the domain, where a conforming mesh is difficult to maintain, e.g. due to large deformations. The FEM is used in the rest of the domain and enables an efficient solution of the underlying partial differential equations. The coupled formulation is successfully applied to flow simulations governed by the incompressible Navier‐Stokes equations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling material property heterogeneity in fiber‐reinforced injection molded plastic parts
Authors: Pochiraju Kishore , Jovanović Vojin 
Published: December 2004

AbstractFiber reinforced plastic parts manufactured by injection molding have heterogeneous stiffness and strength behavior due to the molding process influence on the fiber orientations. This paper presents a methodology for determining the process‐dependent anisotropic and inhomogeneous mechanical properties of injection‐molded parts using a thickness‐wise layered homogenization technique. This technique produces an equivalent laminated meso‐scale representation at any location in the part and enables point‐wise application of the existing laminated plate and shell theories. The methodology is demonstrated by illustrating property variations in edge‐gated and center‐gated plaques. Spatial variations of elastic moduli, shear modulus, and Poisson's ratio are modeled. The model can be conveniently embedded within finite element structural analyses accounting for the process‐dependent material heterogeneities within the structure. POLYM. COMPOS., 26:98–113, 2005. © 2004 Society of Plastics Engineers
Mechanical behavior and dilatation of particulate‐filled thermosets in the glassy state
Authors: Yilmazer U. , Farris R. J. 
Published: December 2004

AbstractDilatation of specimens is measured during tensile tests to investigate the mechanical response of particulate‐filled amorphous networks in the glassy state. The effects of particle size, volume fraction of filler, coupling agents, and crosslink density of the matrix on the mechanical‐dilatational behavior are studied on model composites of glass‐bead‐filled polyurethanes. It is found that the stress‐strain response of composites with untreated glass beads shows nonlinearity and subsequent yielding due to dewetting of particles from the matrix. In contrast, composites containing particles coated with a comupling agent fracture in a brittle manner, showing no significant nonlinearity and dewetting. Coated particles provide a higher tensile strength, but a lower strain at fracture, than uncoated particles. The volume fraction of the filler has an effect on Young's modulus, which is independent of the degree of coupling between the matrix and the filler. Tensile strength and strain at break decrease with increasing filler content for coated and uncoated particles. No strong effect of particle size is observed on either the tensile modulus or the dilatational behavior in the 25 μm to 160 μm diameter range. However, strain at break increases with decreasing particle size. When the accompanying yield phenomena shift to smaller strains, and a transition to brittle fracture takes place at high crosslink densities.
Effect of hygrothermal fatigue on dynamic mechanical properties and morphology of neat and glass‐reinforced vinyl ester composites
Authors: Mijović J. 
Published: December 2004

AbstractA neat vinyl ester and a series of glass‐reinforced vinyl‐ester composites were prepared and investigated. All specimens were exposed to various syclic hygrothermal fatigue treatments, which differed from one another by the temperature and the duration of a cycle. Changes induced by the hygrothermal fatigue were studied by weight‐gain measurements, dynamic‐mechanical analysis, and electron microscopy. The Tg of fatigued composites were found to be determined by the amount of moisture absorbed within the resin network. The overall weight gain, however, also includes the moisture absorbed within the resin‐reinnforcement interphase and is a function of the type of composite, the surface treatment of the reinforcement, and the temperature and duration of the fatigue cycle. A semiquantitative concept of the mechanism of water absorption in themoset‐matrix composites has been advanced on the morphological level in order to interpret the experimental results.
Interfacial interaction between poly(p‐phenylene terephthalamide) filament and nylon 6 matrix crystallized from the melt
Authors: Kumamaru F. , Oono T. , Kajiyama T. , Takayanagi M. 
Published: December 2004

AbstractNylon 6 was isothermally crystallized at 483 K for 45 in the presence of poly(p‐phenylene terephthalamide) (PPTA) filament. Two kinds of traqnscrystalline zones were observed around the surface of PPTA filament by polarized optical microscopy. The two are designated as the interfacial and the intermediate zones from the surface of PPTA filament. The aggregation state of molecular chains in these zones was characterized by means of microbeam x‐ray diffraction and birefringence. The a*‐and the a‐axes of nylon 6 oriented perpendicularly to the filament surface, aligning along the radial direction in the interfacial and intermediate zones, respectively. The b‐ and c‐axes rotate around these a*‐and a‐axes. The DSC measurement revealed that nylon 6 molecules in the interfacial zone crystallized and also melted at a higher temperature, compared with those in the intermediate zone or with the usual three‐dimensional spherulite. Viscoelastic measurement clarified the fact that the interfacial zone had a restraining effect on the molecular motion of nylon 6 in the compostes with PPTA fiber. The interfacial zone is preferable for reinforcing the composite with respect to modulus.
Dynamic mechanical spectroscopy of sheet molding compound as a function of offset stress
Authors: Ard K. , Kolman H. , Venkataswamy K. , Stephens K. , Beatty C. L. 
Published: December 2004

AbstractIt has been determined that preload and cyclic amplitude have significant effect on the results of dynamic mechanical measurements of tan δ. To illustrate these effects on composites, a particular type of sheet molding compound (SMC‐R50) was used in this study. In addition to the effects of preload and cycle amplitude, the effects of frequency, and creep prior to dynamic mechanical testing were also investigated.
The dynamic mechanical method for the characterization of solid composite polymers
Authors: Gearing John W. E. , Stone Margǒt R. 
Published: December 2004

AbstractInformation and parameters obtainable from the dynamic mechanical thermal analysis test method are defined. The sensitivity of the technique in detecting the presence of separate phases is emphasized. The Polymer Laboratories DMTA instrumentation is briefly described and its various modes of operation, such as frequency multiplexing, discussed. The theory of the mechanical response of two phase systems is presented via the Takayanagi model approach. Series and parallel coupling constants are derived for a few systems as examples of the definition of phase morphology. Examples are given of the results for ethylene‐propylene random copolymer, block copolymer elastomers, rubber toughened poly(styrene), carbon fiber reinforced expoxies with different orientations of fiber, and carbon black filled rubbers. The engineering properties of composites are available directly from the PL‐DMTA, which provides sensitive detection of non‐linear mechanical behavior, frequently found in multi‐phase polymer systems.
The application of endless‐fiber reinforced polymers
Authors: Menges G. , Minte J. 
Published: December 2004

AbstractBoth in aircraft and automobile construction, the transition from metals to fiber reinforced polymer resins is taking place with increasing regularity. Beginning with the wide selection of possible materials, definite examples of the mechanical properties of construction parts are discussed in this article. Different production possibilities based on fiber winding technology are shown. The application of robots in production is also considered.
The effect of molding time and temperature on the modulus and glass transition of phenolics
Authors: Landi V. R. , Mersereau J. M. , Dorman S. E. 
Published: December 2004

AbstractThe effects of molding time and temperature on the dynamic mechanical behavior of a novolak phenolic molding compound were measured using the DuPont Dynamic Mechanical Analyzer. Large differences were found in the modulus‐temperature response over the range of curing times (10 to 1800 s.) and temperatures (132 to 218°C) employed. Glass transition temperatures increased well beyond cure temperatures at long cure times. In the asmolded condition, samples cured at lower temperature had higher room temperature modulus than those cured at higher temperatures, and the lower modulus corresponded to lower density. Postbaking by steps up to 232°C increased the glass transition above 280°C, and also served to normalize the modulus differences found in as‐molded samples.
Properties of cellulose‐polyester composites
Authors: Zadorecki Pawel , Flodin Per 
Published: December 2004

AbstractCellulose fibers were used as reinforcement in unsaturated polyesters. Composites were prepared as laminates with cellulose fibers used in the form of paper sheets. The impregnation was carried out in a vacuum and resulted in a composite with uniform distribution of polyester around the fibers. The polyester was also detected in the lumen of the fibers. The tensile properties were evaluated and compared with tensile properties of glass fiber reinforced polyester. It is found that cellulose fibers increase the tensile strength and modulus of a polyester composite. Immersion of the cellulose‐polyester composites in water caused a considerable water uptake. The presence of water in the composites decreased the tensile properties drastically. Scanning electron photomicrographs of the tensile fracture surfaces showed a lack of adhesion between the cellulose fibers and the polyester matrix in wet conditions.
Optimization of polyester sheet molding compound. Part I: Experimental study
Authors: Fan J. D. , Marinelli J. M. , Lee L. James 
Published: December 2004

AbstractA series of differential scanning calorimetry (DSC) and molding experiments were carried out to measure the effect of curing agents, namely initiators and inhibitor, on the SMC reaction. Results showed that the induction time, the reaction rate, and the limiting conversion of sheet molding compounds can be modified through the change of curing agents. The SMC resin with a higher concentration of low temperature initiator and molded at higher temperature may cure in a shorter period of time and reach a higher conversion. The shortened scorch time and shelf life can be balanced by adding small amount of inhibitor. Surface quality of molded SMC parts measured by solvent extraction process showed that limiting conversion is an important factor in SMC molding.
Influence of talc's morphological characteristics on the toughness of a composite based on low‐density polyethylene and polypropylene blends
Authors: Ramos M. Arroyo , Matheu J. P. Vigo 
Published: December 2004

AbstractThe toughness of polymer composites based on low‐density polyethylene (LDPE)/polypropylene (PP) blends and filled with talcs of different particle size and particle size distribution was studied applying the two‐variable Box‐Hunter method of optimization. The effect of the polymer matrix composition and percent talc on the Charpy impact strength of the composites, at –30°C, was investigated. The results show a change in the polymer matrix behavior at PP contents of 60% and 75%, depending on talc particle size. At these percentages of PP, toughness exhibits a minimum that becomes lower as the filler content is increased. Optical microscopy shows a nucleating effect of the talc particles for the crystalline polymer. The larger the talc particle size, the higher the nucleation density. The minimum toughness arises at higher PP content in the matrix. At PP contents in the matrix below 35%, the filler has a minimal effect on composite toughness.
Molecular composites based on thermosetting matrix polymers: Poly(p‐phenyleneterephthalamide)‐epoxy
Authors: Moore D. R. , Mathias L. J. 
Published: December 2004

AbstractPoly(p‐phenyleneterephthalamide) (PPTA) reinforced molecular composites that utilize a thermosetting epoxy as the matrix polymer have been prepared by an in situ polymerization process. The properties of these molecular composites were compared with those of Kevlar pulp‐filled composites that utilized the same matrix formulation. Study of the curing reactions of these systems using Fourier transform infrared, dynamic mechanical analysis, and nuclear magnetic resonance spectroscopy indicated some differences in the reactivity and ultimate polymer structure of these two systems. A comparison of the properties indicated increased tensile strength, modulus, and heat resistance for the molecularly reinforced material over the conventional fiber‐filled system. Examination of the morphology of the molecular composite system showed that aggregated PPTA molecules are formed during the in situ polymerization process. This aggregation phenomenon was found to be due to formation of a liquid crystalline polymer solution during processing and final cure. These findings indicate the possibilities that exist in molecular composite processing for simultaneous control of the properties of the matrix and the reinforcement.