bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of microcrystallinity and morphology on physical aging of poly(ethylene terephthalate)
Authors: Zhou Hongxia , Lofgren Elizabeth A. , Jabarin Saleh A. 
Published: August 2007

AbstractPhysical aging characteristics of poly(ethylene terephthalate) have been evaluated in relationship to volume fraction levels of crystallinity up to 25%. Changes in the enthalpies of relaxation, monitored at aging temperatures from 55 to 65°C, are found to give good fits with the Cowie‐Ferguson model. Overall equilibrium enthalpy of relaxation values decrease linearly with increased crystallinity. They increase with decreased aging temperature, providing extrapolated lower temperature results that are validated in terms of specific heat relationships. Activation energies for enthalpic relaxations are found to increase from 337 to 361 kJ/mole as crystallinity increases up to 25%. Overall relaxation endotherms are further resolved into contributions from interspherulitic and intraspherulitic amorphous regions. Interspherulitic, equilibrium enthalpies of relaxation decrease with increased levels of crystallinity, while intraspherulic values show corresponding increases. Characteristic relaxation times of the intraspherulic regions increase greatly, as levels of crystallinity increase; however, interspherulitic relaxation times decrease very slightly. Dynamic differential scanning calorimetry results show two glass transitions in the case of a 25% crystalline sample and a single transition for noncrystallized material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Developing electrically conductive polypropylene/polyamide6/carbon black composites with microfibrillar morphology
Authors: Garmabi Hamid , Naficy Sina 
Published: August 2007

AbstractWe have established that the PP/PA6/CB composite with 3D microfibrillar conducting network can be prepared in situ using melt spinning process. CB particles preferably were localized at the interface between polypropylene as the matrix and PA6 microfibrils, which act as the conducting paths inside the matrix. The percolation threshold of the system reduced when aspect ratio of the conducting phase was increased by developing microfibrillar morphology. The effect of annealing process on the conductivity of PP/PA6/CB composite with co‐ continuous and microfibrillar morphologies was studied. It was observed that, annealing process forces CB particles towards the interface (2D space) of PP and PA6 co‐continuous phases, and percolation threshold and critical exponent of classical percolation theory will be decreased, while the conductivity of conducting composite with microfibrillar morphology was not affected considerably by annealing process at temperatures either higher or lower than the melting point of the PA6 microfibrils. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis, characterization, and kinetic study of functional polystyrenes
Authors: Doğan Fatih , Kaya İsmet , Dayan Osman , Özdemir Eyüp 
Published: August 2007

AbstractIn this study, functionalization of polystyrene (PS) (Mn = 2.5 × 105) was carry out with maleic anhydride in the presence of boron trifluoride dietyhletherade (BF3 OEt2) as catalyst and then functional PS was subjected to condensation reaction with phenyl hydrazine. The structures of both of them were determined by using FTIR, 1H‐NMR, elemental analysis, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. Some physical properties of these two products were investigated and the kinetic parameters of solid state decomposition reactions were determined from TGA curves. The intrinsic viscosity [η] values of modified PS and condensation products (cPs) found to be 1.024 and 0.7036 dL g−1, respectively. According to TGA, the weight losses of modified PS and cPs were found to be 84.03 and 81.86%, respectively, at 500°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Viscoelastic properties of natural rubber composites reinforced by defatted soy flour and carbon black co‐filler
Authors: Jong L. 
Published: August 2007

AbstractFiller mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce natural rubber (NR) composites and their viscoelastic properties were investigated. DSF is an abundant and renewable commodity and has a lower material cost than CB. Aqueous dispersions of DSF and CB were first mixed and then blended with NR latex to form rubber composites using freeze‐drying and compression molding methods. A 40% co‐filler reinforced composite with a 1 : 1 DSF : CB ratio exhibited a 90‐fold increase in the rubber plateau modulus compared with unfilled NR, showing a significant reinforcement effect by the co‐filler. The effect, however, is lower than that observed in the carboxylated styrene–butadiene rubber composites reported earlier, indicating a significant effect from the rubber matrix. The co‐filler composites have elastic moduli between those of DSF and CB reinforced composites. Stress softening and recovery experiments indicated that the co‐filler composites with a higher CB content tend to have a better recovery behavior; however, this can not be simply explained from the recovery behaviors of the single filler (DFS and CB) composites. CB composites prepared by freeze‐drying show a strain‐induced reorganization of fillers. Strain sweep experiment data fit with the Kraus model indicates the co‐filler composites with a higher CB content are more elastic, which is consistent with the recovery experiments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis and application of polyoxyethylene‐grafted cationic polyamidoamine dendrimers as retention aids
Authors: Peng Xiaochun , Peng Xiaohong , Zhao Jianqing 
Published: August 2007

AbstractNovel derivatives of fifth‐generation polyamidoamine, comprising polyoxyethylene macromonomer and acrylolyoxyethyl trimethylammonium chloride units, were synthesized. The polyoxyethylene‐grafted cationic polyamidoamine dendrimers were characterized with Fourier transform infrared,1H‐NMR,13C‐NMR, and elemental analysis. The synthesis recipes and properties of the dendrimers were studied. The retention efficiency of the dendrimers was determined and discussed. Highly effective retention aids were obtained in retention experiments with broadleaf wood pulp fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Factors influencing magnetic polymer microspheres prepared by dispersion polymerization
Authors: Zeng Hongmei , Lai Qiongyu , Liu Xueqi , Wen De , Ji Xiaoyang 
Published: August 2007

AbstractMagnetic iron oxide (Fe3O4) was prepared by a coprecipitation method. Core–shell composite magnetic polymer microspheres with carboxyl groups were synthesized by the dispersion polymerization of styrene and acrylic acid in the presence of magnetic oxide, and dibenzoyl peroxide was used as an initiator. The synthesized magnetic polymer microspheres were characterized with X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and so forth. The results indicated that the product was single‐phase Fe3O4, and its average size was about 10 nm. The configuration of the microspheres, which contained carboxyl groups, was spherical, and the average size was about 2 μm. The results of vibrating sample magnetometry tests showed that the magnetic powders produced by different surfactants had different saturation magnetizations. When poly(ethylene glycol) with a weight‐average molecular weight of 4000 was used as a surfactant, the saturation magnetization of the samples reached 69.2 emu/g. The factors that affected the shape, magnetism, size, and distribution of the microspheres were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Vulcanization of polybutadiene rubber with dipentamethylene thiuram tetrasulfide
Authors: Posadas P. , Fernández A. , Brasero J. , Valentín J. L. , Marcos A. , Rodríguez A. , González L. 
Published: August 2007

AbstractThe cure of polybutadiene rubber (BR) with sulfur donor dipentamethylene thiuram tetrasulfide (DPTT) does not show reversion reaction, in contrast with similar natural rubber compounds. No polysulfure links are formed; whereas a great amount of CC crosslinks are produced. The addition of tetramethyl thiuram monosulfidic (TMTM) strongly affects the crosslinking process. Mechanical properties of the cured compounds are poor. In DPTT, curing of BR the radical species produced through homolitic cleavage of DPTT molecule seems to have sufficient energy to produce crosslinking, via allylic abstraction, and also initiate the polymerization of double bonds producing areas of high crosslinking density that induce early material failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 106: 3481–3487, 2007
Influences of catalysis and dispersion of organically modified montmorillonite on flame retardancy of polypropylene nanocomposites
Authors: Song Rongjun , Wang Zhe , Meng Xiaoyu , Zhang Baoyan , Tang Tao 
Published: August 2007

AbstractThe degradation and flame retardancy of polypropylene/organically modified montmorillonite (PP/OMMT) nanocomposite were studied by means of gas chromatography‐mass spectrometry and cone calorimeter. The catalysis of hydrogen proton containing montmorillonite (H‐MMT) derived from thermal decomposition of (alkyl) ammonium in the OMMT on degradation of PP strongly influence carbonization behavior of PP and then flame retardancy. Brønsted acid sites on the H‐MMT could catalyze degradation reaction of PP via cationic mechanism, which leads to the formation of char during combustion of PP via hydride transfer reaction. A continuous carbonaceous MMT‐rich char on the surface of the burned residues, which work as a protective barrier to heat and mass transfer, results from the homogeneous dispersion of OMMT in the PP matrix and appropriate char produced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Chemical modification of polyaniline by N‐grafting of polystyrene synthesized via ATRP
Authors: Gheybi Homa , Abbasian Mojtaba , Moghaddam Peyman Najafi , Entezami Ali Akbar 
Published: August 2007

AbstractThe N‐substituted polyaniline (PANi) was synthesized by incorporation of bromine‐terminated polystyrene (PS‐Br) onto the emeraldine form of polyaniline. End brominated polystyrene was synthesized by atom transfer radical polymerization (ATRP) technique and then deprotonated polyaniline was reacted with PS‐Br to prepare PS‐grafted PANi (PS‐g‐PANi) copolymer through N‐grafting reaction. The degree of N‐grafting can be controlled by adjusting the molar feed ratio of PS‐Br to the number of repeat units of PANi. The microstructure and compositions of the PS‐g‐PANi copolymers with different degrees of N‐substitution were characterized by FT‐IR, elemental analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The cyclicvoltammetry shows that the electroactivity of N‐substituted PANi is strongly dependent on the degree of N‐grafting. The solubility of PS‐g‐PANi copolymers in common organic solvents such as tetrahydrofuran and chloroform was improved by increasing the degree of N‐grafting, and also the samples are partially soluble in xylene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Techniques for Modeling Muscle‐induced Forces in Finite Element Models of Skeletal Structures
Authors: Grosse Ian R. , Dumont Elizabeth R. , Coletta Chris , Tolleson Alex 
Published: August 2007

AbstractThis work introduces two mechanics‐based approaches to modeling muscle forces exerted on curvilinear bone structures and compares the results with two traditional ad hoc methods of muscle loading. These new models use a combination of tensile, tangential, and normal traction loads to account for muscle fibers wrapped around curved bone surfaces. A computer program was written to interface with a commercial finite element analysis tool to automatically apply traction loads to surface faces of elements in muscle attachment regions according to the various muscle modeling methods. We modeled a highly complex skeletal structure, the skull of a Jamaican fruit bat (Artibeus jamaicensis), to compare the four muscle‐loading methods. While reasonable qualitative agreement was found in the states of stress of the skull between the four muscle load modeling methods, there were substantial quantitative differences predicted in the stress states in some high stressed regions of the skull. Furthermore, our mechanics‐based models required significantly less total applied muscle force to generate a bite‐point reaction force identical to those produced by the ad hoc muscle loading models. Although the methods are not validated by in vivo data, we submit that muscle‐load modeling methods that account for the underlying physics of muscle wrapping on curved bone surfaces are likely to provide more realistic results than ad hoc approaches that do not. We also note that, due to the geometric complexity of many bone structures—such as the skull analyzed here—load transmission paths are difficult to conceptualize a priori. Consequently, it is difficult to predict spatially where the results of finite element analyses are likely to be compromised by using ad hoc muscle modeling methods. For these reasons, it is recommended that a mechanics‐based method be adopted for determination of the proper traction loads to be applied to skeletal structures due to muscular activity. Anat Rec, 290:1069–1088, 2007. © 2007 Wiley‐Liss, Inc.
Structural Characteristics and Development of Ampullary Organs in Acipenser naccarii
Authors: Camacho Susana , Ostos Maria Del Valle , Llorente José Ignacio , Sanz Ana , García Manuel , Domezain Alberto , Carmona Ramón 
Published: August 2007

AbstractAmpullary organs of Acipenser naccarii sturgeons were examined by optical and electronic microscopy (transmission electron microscopy and scanning electron microscopy) from hatching until 1 month later when the juvenile phase is completely established. It was observed that, when A. naccarii begins to feed actively, the ultrastructural characteristics of ampullary organs already correspond to those of adult animals. These organs may, therefore, be functional and, together with taste buds, facilitate food search after exhaustion of yolk sac food reserves. Mature ampullary organs of A. naccarii are formed by an ampulla that communicates with the exterior by means of a short channel. These ampullae correspond to the sensory portion of these receptors and are formed by two cell types: receptor cells and support cells. Receptor cells present a kinocilium on their free surface and establish ribbon synapses with axon nerve endings that arise from the underlying conjunctive tissue. Support cells enclose receptor cells, bear stereocilia and occasional cilia, and are of a secretory nature. The mucus associated with ampullary organs mainly comprises neutral mucopolysaccharides, whereas mucopolysaccharides are usually acid in other fish groups. Anat Rec, 290:1178–1189, 2007. © 2007 Wiley‐Liss, Inc.
Neuromuscular Anatomy and Evolution of the Cetacean Forelimb
Authors: Cooper Lisa Noelle , Dawson Susan D. , Reidenberg Joy S. , Berta Annalisa 
Published: August 2007

AbstractThe forelimb of cetaceans (whales, dolphins, and porpoises) has been radically modified during the limb‐to‐flipper transition. Extant cetaceans have a soft tissue flipper encasing the manus and acting as a hydrofoil to generate lift. The neuromuscular anatomy that controls flipper movement, however, is poorly understood. This study documents flipper neuromuscular anatomy and tests the hypothesis that antebrachial muscle robustness is related to body size. Data were gathered during dissections of 22 flippers, representing 15 species (7 odontocetes, 15 mysticetes). Results were compared with published descriptions of both artiodactyls and secondarily aquatic vertebrates. Results indicate muscle robustness is best predicted by taxonomic distribution and is not a function of body size. All cetaceans have atrophied triceps muscles, an immobile cubital joint, and lack most connective tissue structures and manus muscles. Forelimbs retain only three muscle groups: triceps (only the scapular head is functional as the humeral heads are vestigal), and antebrachial extensors and flexors. Well‐developed flexor and extensor muscles were found in mysticetes and basal odontocetes (i.e., physeterids, kogiids, and ziphiids), whereas later diverging odontocetes (i.e., monodontids, phocoenids, and delphinids) lack or reduce these muscles. Balaenopterid mysticetes (e.g., fin and minke whales) may actively change flipper curvature, while basal odontocetes (e.g., sperm and beaked whales) probably stiffen the flipper through isometric contraction. Later diverging odontocetes lack musculature supporting digital movements and are unable to manipulate flipper curvature. Cetacean forelimbs are unique in that they have lost agility and several soft tissue structures, but retain sensory innervations. Anat Rec, 290:1121–1137, 2007. © 2007 Wiley‐Liss, Inc.
Somatosensory Nuclei of the Manatee Brainstem and Thalamus
Authors: Sarko Diana K. , Johnson John I. , Switzer Robert C. , Welker Wally I. , Reep Roger L. 
Published: August 2007

AbstractFlorida manatees have an extensive, well‐developed system of vibrissae distributed over their entire bodies and especially concentrated on the face. Although behavioral and anatomical assessments support the manatee's reliance on somatosensation, a systematic analysis of the manatee thalamus and brainstem areas dedicated to tactile input has never been completed. Using histochemical and histological techniques (including stains for myelin, Nissl, cytochrome oxidase, and acetylcholinesterase), we characterized the relative size, extent, and specializations of somatosensory regions of the brainstem and thalamus. The principal somatosensory regions of the brainstem (trigeminal, cuneate, gracile, and Bischoff's nucleus) and the thalamus (ventroposterior nucleus) were disproportionately large relative to nuclei dedicated to other sensory modalities, providing neuroanatomical evidence that supports the manatee's reliance on somatosensation. In fact, areas of the thalamus related to somatosensation (the ventroposterior and posterior nuclei) and audition (the medial geniculate nucleus) appeared to displace the lateral geniculate nucleus dedicated to the subordinate visual modality. Furthermore, it is noteworthy that, although the manatee cortex contains Rindenkerne (barrel‐like cortical nuclei located in layer VI), no corresponding cell clusters were located in the brainstem (“barrelettes”) or thalamus (“barreloids”). Anat Rec, 290:1138–1165, 2007. © 2007 Wiley‐Liss, Inc.
Optical Coherence Tomography as a Tool for Measuring Morphogenetic Deformation of the Looping Heart
Authors: Filas Benjamen A. , Efimov Igor R. , Taber Larry A. 
Published: August 2007

AbstractOptical coherence tomography (OCT) was used to investigate morphogenesis of the embryonic chick heart during the first phase of looping (c‐looping), as the heart bends and twists into a c‐shaped tube. The present study focuses on the morphomechanical effects of the splanchnopleure (SPL), a membrane that has been shown to play a major role in cardiac torsion by pressing against the ventral surface of the heart. Without the SPL, rightward torsion (rotation) is delayed. The images show that compressive forces exerted by the SPL alter the shapes of the heart tube and primitive atria, as well as their spatial relationships. The SPL normally holds the heart in the plane of the embryo and forces cardiac jelly (CJ) out of adjacent regions in the atria. When the SPL is removed, cross‐sections become more circular, CJ is more uniformly distributed, and the heart displaces ventrally. In addition, OCT‐based morphogenetic strain maps were measured during looping by tracking the three‐dimensional motions of microspheres placed on the myocardium. The spatial–temporal patterns of the strains correlated well with the observed behavior of the heart, including delayed torsion that occurs in SPL‐lacking embryos. These results illustrate the potential of OCT as a tool in studies of morphogenesis, as well as provide a better understanding of the mechanical forces that drive cardiac looping. Anat Rec, 290:1057–1068, 2007. © 2007 Wiley‐Liss, Inc.
Innervation and Neurotransmitter Localization in the Lung of the Nile bichir Polypterus bichir bichir
Authors: Zaccone Giacomo , Mauceri Angela , Maisano Maria , Giannetto Alessia , Parrino Vincenzo , Fasulo Salvatore 
Published: August 2007

AbstractAnatomical and functional studies of the autonomic innervation in the lung of dipnoan fishes and the bichirs are lacking. The present immunohistochemical studies demonstrated the presence of nerve fibers in the muscle layers of the lung of the bichir, Polypterus bichir bichir, and identified the immunoreactive elements of this innervation. Tyrosine hydroxylase, acetylcholinesterase, and peptide immunoreactivity was detected in the intramural nerve fibers. Extensive innervation was present in the submucosa where adenylatecyclase/activating polypeptide 38, substance P, P2X2, and 5‐hydroxytryptamine (5‐HT)–immunoreactive nerve fibers mainly supplied blood vessels. A collection of monopolar neurons located in the submucosal and the muscular layers of the glottis expressed a variety of various transmitters. These neurons may be homologous to ganglion cells in the branchial and pharyngeal rami of the vagus in fishes. Nerves containing 5‐HT and P2X2 receptor immunoreactivity projected to the lung epithelium. Associated with neuroepithelial cells in mucociliated epithelium, were neuronal nitric oxide synthase–immunopositive axons. The physiological function of this innervation is not known. The present study shows that the pattern of autonomic innervation of the bichir lung may by similar in its elements to that in tetrapods. Anat Rec, 290:1166–1177, 2007. © 2007 Wiley‐Liss, Inc.
Linear and Geometric Morphometric Analysis of Long Bone Scaling Patterns in Jurassic Neosauropod Dinosaurs: Their Functional and Paleobiological Implications
Authors: Bonnan Matthew F. 
Published: August 2007

AbstractNeosauropod dinosaurs were gigantic, herbivorous dinosaurs. Given that the limb skeleton is essentially a plastic, mobile framework that supports and moves the body, analysis of long bone scaling can reveal limb adaptations that supported neosauropod gigantism. Previously, analyses of linear dimensions have revealed a relatively isometric scaling pattern for the humerus and femur of neosauropods. Here, a combined scaling analysis of humerus and femur linear dimensions, cortical area, and shape across six neosauropod taxa is used to test the hypothesis that neosauropod long bones scaled isometrically and to investigate the paleobiological implications of these trends. A combination of linear regression and geometric morphometrics analyses of neosauropod humeri and femora were performed using traditional and thin‐plate splines approaches. The neosauropod sample was very homogeneous, and linear analyses revealed that nearly all humerus and femur dimensions, including cortical area, scale with isometry against maximum length. Thin‐plate splines analyses showed that little to no significant shape change occurs with increasing length or cortical area for the humerus or femur. Even with the exclusion of the long‐limbedBrachiosaurus, the overall trends were consistently isometric. These results suggest that the mechanical advantage of limb‐moving muscles and the relative range of limb movement decreased with increasing size. The isometric signal for neosauropod long bone dimensions and shape suggests these dinosaurs may have reached the upper limit of vertebrate long bone mechanics. Perhaps, like stilt‐walkers, the absolutely long limbs of the largest neosauropods allowed for efficient locomotion at gigantic size with few ontogenetic changes. Anat Rec, 290:1089–1111, 2007. © 2007 Wiley‐Liss, Inc.