bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the blend ratio and crosslinking systems on the curing behavior, morphology, and mechanical properties of styrene–butadiene rubber/poly(ethylene‐co‐vinyl acetate) blends
Authors: Radhakrishnan C. K. , Sujith A. , Unnikrishnan G. , Thomas Sabu 
Published: August 2004

AbstractBlends of styrene–butadiene rubber (SBR) and poly(ethylene‐co‐vinyl acetate) (EVA) with different ratios were prepared with a two‐roll mixing mill and were vulcanized by three different crosslinking systems, namely, sulfur (S), dicumyl peroxide, and a mixture consisting of S and peroxide (mixed). The vulcanization behavior of the blends was analyzed from the rheographs. The mechanical properties, including stress–strain behavior, tensile strength, elongation at break, modulus, hardness, and abrasion resistance, of the blends were examined. The morphology of the prepared blends was studied with scanning electron microscopy with special reference to the effects of the blend ratio and crosslinking systems. A relatively cocontinuous morphology was observed for the 20/80 SBR/EVA composition. The mechanical properties increased with increasing EVA content up to 60–80%, for all of the vulcanizing modes. The tensile fracture surfaces were analyzed under a scanning electron microscope to understand the failure mechanism. Various theoretical models were applied to explain the properties of the blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 827–837, 2004
Synthesis and structural characterization of a new polysiloxane with second‐order nonlinear optical effect
Authors: Li Zhen , Qin Jingui , Yang Zhou , Ye Cheng 
Published: August 2004

AbstractA new polysiloxane (P2), with a high density of the indole‐based chromophore and carbazolyl side groups, was prepared. Thus a polysiloxane (P1), with indole and carbazolyl groups as side chains, was first synthesized through a hydrosilylation reaction, and then the post‐azo coupling of p‐nitrobenzenediazonium fluoroborate toward the indole ring gave the mulifunctional indole‐based chromophore‐functionalized polysiloxane (P2). Molecular structural characterization for the polymers was determined by 1H‐NMR, IR, and UV–visible spectra, gel permeation chromatography, and differential scanning calorimetry. The polymers were easily soluble in common organic solvents. The poled film of P2 revealed a resonant d33 value of 27 pm/V by second‐harmonic generation measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 769–774, 2004
Water‐dispersible conducting nanocomposites of binary polymer systems. I. Poly(N‐vinylcarbazole)–polyaniline–Al2O3 nanocomposite system
Authors: Maity Arjun , Biswas Mukul 
Published: August 2004

AbstractThe chemical oxidative polymerization of a mixture of N‐vinylcarbazole (NVC) and aniline (ANI), by FeCl3 in aqueous medium, produced an insoluble polymer that contained polyaniline (PANI), along with some residual poly‐N‐vinylcarbazole (PNVC) not extractable with benzene. This insoluble PNVC–PANI composite could be obtained as a stable suspension in water when the above polymerization was conducted in the presence of nanodimensional Al2O3. Alternatively, PNVC–(PANI–Al2O3) composite could also be produced by precipitating a THF solution of preformed PNVC onto a PANI–Al2O3 suspension. Likewise PANI–(PNVC–Al2O3) could be obtained by polymerizing ANI onto an aqueous suspension of PNVC–Al2O3. The inclusion of either of these monomer units in the resultant polymer was confirmed by FTIR analysis. SEM analyses revealed formation of a lumpy aggregate, and TEM analyses confirmed particle sizes of the PNVC–PANI–Al2O3 composite to be in the 52–200 nm range. Thermogravimetric stability was in the order: PANI–Al2O3 < PNVC–PANI–Al2O3 < PNVC–Al2O3. The dc conductivity values (S/cm) followed the trend: PNVC–Al2O3 (10−7) < PNVC–PANI–Al2O3 (1.5 × 10−4) ≈ PANI–Al2O3 (1.1 × 10−4) < PNVC–PANI (1 × 10−3) at ambient temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 803–811, 2004
Gas permeabilities of NH3‐plasma‐treated polyethersulfone membranes
Authors: Iwa T. , Kumazawa H. , Bae S.‐Y. 
Published: August 2004

AbstractThe effect of NH3‐plasma treatment on glassy polyethersulfone (PES) membranes upon the diffusion process for CO2, O2, and N2. was investigated from the permeability measurements. The permeation behavior for O2 and CO2 in untreated and NH3‐plasma‐treated PES membranes was simulated well in terms of the dual‐mode mobility model. For O2 transport, NH3‐plasma treatment on PES membrane had a little influence on the diffusion process of Langmuir species and very little influence on the diffusion process of Henry's law species. For CO2 transport, it promoted the transport of Henry's law mode but had very little influence on the transport process of Langmuir species. Both the mean permeability coefficient to CO2 and the ideal separation factor for CO2 relative to N2 took maximum values at a treatment power of 40 W. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 758–762, 2004
Microemulsion copolymerization of methyl methacrylate with acrylonitrile
Authors: Reddy G. V. Ramana , Kumar C. Ramesh , Sriram R. 
Published: August 2004

AbstractThe microemulsion (ME) and conventional emulsion (CE) copolymerizations of methyl methacrylate (MMA) with acrylonitrile (AN) are carried out at 70°C by employing n‐butyl cellosolve as cosurfactant along with sodium lauryl sulfate as surfactant in the reaction medium and potassium persulfate as initiator. The copolymers are characterized by FTIR, NMR, TG/DTA, and GPC techniques. The reactivity ratios are evaluated by employing Fineman‐Ross, Kellen‐Tüdös (K‐T), and Mayo‐Lewis integration methods. The K‐T method yields reactivity ratios, rMMA and rAN, for the ME copolymerization of MMA and AN of 1.06 ± 0.01 and 0.14 ± 0.01, and those for the CE copolymerization of MMA and AN are 2.19 ± 0.01 and 0.14 ± 0.01, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 739–747, 2004
Surface‐modified silica nanoparticle–reinforced poly(ethylene 2,6‐naphthalate)
Authors: Ahn Seon Hoon , Kim Seong Hun , Lee Seung Goo 
Published: August 2004

AbstractThe effect of stearic acid modification on the dispersity of silica nanoparticles and the adhesion between the filler and polymer matrix with stearic acid concentration were investigated. The wettability of silica nanoparticles was improved by the addition of stearic acid. The presence of adsorbed stearic acid on the surface of the silica nanoparticles reduced the interaction between silica nanoparticles, and reduced the size of agglomerates with increasing concentration. Silica nanoparticle–reinforced poly(ethylene 2,6‐naphthalate) (PEN) composites were melt‐blended to investigate their mechanical properties and the processability of the composites. The torque and total torque values of the composites decreased with increasing silica nanoparticle content. The tensile moduli of the composites reinforced with unmodified silica nanoparticles increased with increasing silica content, whereas the tensile strength and elongation decreased. However, the stearic acid–modified silica nanoparticle–reinforced PEN composites exhibited increased elongation and decreased tensile moduli with increasing content because stearic acid, which adsorbs onto the surface of the silica nanoparticles in layers thicker than a monolayer, acts as a plasticizer during the melt‐compounding stage. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 812–818, 2004
Isothermal and nonisothermal crystallization kinetics of a semicrystalline copolyterephthalamide based on poly(decamethylene terephthalamide)
Authors: Liu Hongzhi , Yang Guisheng , He Aihua , Wu Meiyan 
Published: August 2004

AbstractThe isothermal and nonisothermal crystallization kinetics of a semicrystalline copolyterephthalamide based on poly(decamethylene terephthalamide) (PA‐10T) was studied by differential scanning calorimetry. Several kinetic analyses were used to describe the crystallization process. The commonly used Avrami equation and the one modified by Jeziorny were used, respectively, to describe the primary stage of isothermal and nonisothermal crystallization. The Avrami exponent n was evaluated to be in the range of 2.36–2.67 for isothermal crystallization, and of 3.05–5.34 for nonisothermal crystallization. The Ozawa analysis failed to describe the nonisothermal crystallization behavior, whereas the Mo–Liu equation, a combination equation of Avrami and Ozawa formulas, successfully described the nonisothermal crystallization kinetics. In addition, the value of crystallization rate coefficient under nonisothermal crystallization conditions was calculated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 819–826, 2004
TERC is not a major gene in human neural tube defects
Authors: Benz Lisa P. , Swift Frances E. , Graham Felicia L. , Enterline David S. , Melvin Elizabeth C. , Hammock Preston , Gilbert John R. , Speer Marcy C. , Bassuk Alexander G. , Kessler John A. , George Timothy M. ,   and the NTD Collaborative Group
Published: August 2004

AbstractBACKGROUNDNeural tube defects (NTDs) are the second most common birth defects, after congenital heart defects. Telomerase, the reverse transcriptase that maintains telomere DNA, has been shown to be important for neural tube development and bilateral symmetry in the brain. In knockout mice null for the telomerase RNA component (TERC), telomere loss results in the failure of neural tube closure, primarily at the forebrain and midbrain.METHODSWe investigated TERC for variants that may predispose to human NTDs in 477 NTD cases with a variety of phenotypic presentations.RESULTSTwo novel single nucleotide polymorphisms were identified in the human TERC sequence but showed no association with the NTD phenotype.CONCLUSIONSVariants in TERC are unlikely to be a major risk factor for the most common form of human NTDs, lumbosacral myelomeningocele. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Searching for folding initiation sites of staphylococcal nuclease: A study of N‐terminal short fragments
Authors: Dai Jixun , Wang Xu , Feng Yingang , Fan Guibao , Wang Jinfeng 
Published: August 2004

AbstractThe N‐terminal short fragments of staphylococcal nuclease (SNase), SNase20, SNase28, and SNase36, corresponding to the sequence regions, Ala1–Gly20, Ala1–Lys28, and Ala1–Leu36, respectively, as well as an 8‐residue peptide (Ala17–Ile18–Asp19–Gly20–Asp21–Thr22–Val23–Lys24) have been synthesized. The conformational states of these fragments were investigated using CD and NMR spectroscopy in aqueous solution and in trifluoroethanol (TFE)–H2O mixture. SNase20 containing a sequence corresponding to a bent peptide in native SNase shows a transient population of bend‐like conformation around Ala12–Thr13–Leu14 in TFE–H2O mixture. The sequence region of Ala17–Thr22 of SNase28 displays a localized propensity for turn‐like conformation in both aqueous solution and TFE—H2O mixture. The conformational ensemble of SNase36 in aqueous solution includes populated turn‐like conformations localized in sequence regions Ala17–Thr22 and Tyr27–Gln30. The analysis suggests that these sequence regions, which form the regular secondary structures in native protein, may serve as the folding nucleation sites of SNase fragments of different chain lengths starting from the N‐terminal end. Thus, the formation of bend‐ and turn‐like conformations of these sequence regions may be involved in the early folding events of the SNase polypeptide chain in vitro. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Motility of a biflagellate sperm: Waveform analysis and cyclic nucleotide activation
Authors: Howard David R. , Trantow Colleen M. , Thaler Catherine D. 
Published: August 2004

AbstractThe sperm of the freshwater clam Corbicula fluminea are unusual in that they have two flagella, both of which are capable of beating. When Corbicula sperm are removed from the gonad and placed into freshwater, most remain immotile. Video microscopy was used to assess signaling molecules capable of activating Corbicula sperm motility. Experiments using the cAMP analogs dbcAMP or 8‐Br‐cAMP show that elevating cAMP activates flagellar motility. Treatments with 8‐Br‐cGMP activated motility in similar numbers of sperm. Treatments with the selective cAMP‐dependent protein kinase (PKA) inhibitor H‐89 block activation by 8‐Br‐cAMP but not by 8‐Br‐cGMP. Similar treatments with the cGMP‐dependent protein kinase (PKG) inhibitor Rp‐8‐pCPT‐cGMPS block activation by 8‐Br‐cGMP but not by 8‐Br‐cAMP. These results suggest that cAMP and cGMP each work through their specific kinase to activate flagellar motility. Analysis of spontaneously activated freely swimming sperm shows that the two flagella beat with different parameters. The A flagellum beats with a shorter wavelength and a higher frequency than the B flagellum. The observed differences in flagellar waveform indicate that the flagella are differentially controlled. Cell Motil. Cytoskeleton 59:120–130, 2004. © 2004 Wiley‐Liss, Inc.
Independent maturation of the GABAB receptor subunits GABAB1 and GABAB2 during postnatal development in rodent brain
Authors: Fritschy Jean‐Marc , Sidler Corinne , Parpan Franziska , Gassmann Martin , Kaupmann Klemens , Bettler Bernhard , Benke Dietmar 
Published: August 2004

AbstractGABAB receptors mediate slow inhibitory GABAergic neurotransmission. They are encoded by two distinct subunits, GABAB1 (GBR1) and GABAB2 (GBR2), with two major isoforms of GBR1, GBR1a and GBR1b, arising from differential promoter usage. Heterodimerization of GBR1 and GBR2 is essential for GABAB receptor function, as shown in recombinant expression systems and in GBR1−/− mice. GABAB receptors are highly expressed during ontogeny, prior to synaptogenesis, but their developmental function remains elusive. Here we investigated the postnatal development of GABAB receptors in rodent brain, focusing on potential differences in the spatial and temporal expression pattern of GBR1 and GBR2. Immunohistochemistry with subunit‐specific antibodies revealed a widespread staining for GBR1a and GBR2 in neonatal rodent brain. During the first 2 weeks, these two subunits exhibited largely overlapping regional distribution, but with profound distinctions in cellular and subcellular localization. The adult‐like pattern was established during the third week, with a prominent up‐regulation of GBR1b, extensively codistributed with GBR2. Several unexpected features were noted at early stages, notably, a selective GBR2 staining of axonal tracts, such as the corticothalamic projection, and a prominent GBR1 expression in astrocytes. The specificity of the antibody labeling was verified in GBR1‐ and GBR2‐knockout mice. In addition, the analysis of these mutants revealed a partial preservation of GBR2 staining in GBR1−/− mice and vice versa. Altogether, the results suggest a functional role for GBR1 and GBR2 proteins in immature brain in addition to their contribution to dimeric GABAB receptor complexes. J. Comp. Neurol. 477:235–252, 2004. © 2004 Wiley‐Liss, Inc.
Differential distribution of synaptic endings containing glutamate, glycine, and GABA in the rat dorsal cochlear nucleus
Authors: Rubio Maria E. 
Published: August 2004

AbstractThe dorsal cochlear nucleus (DCN) integrates the synaptic information depending on the organization of the excitatory and inhibitory connections. This study provides, qualitatively and quantitatively, analyses of the organization and distribution of excitatory and inhibitory input on projection neurons (fusiform cells), and inhibitory interneurons (vertical and cartwheel cells) in the DCN, using a combination of high‐resolution ultrastructural techniques together with postembedding immunogold labeling. The combination of ultrastructural morphometry together with immunogold labeling enables the identification and quantification of four major synaptic inputs according to their neurotransmitter content. Only one category of synaptic ending was immunoreactive for glutamate and three for glycine and/or γ‐aminobutyric‐acid (GABA). Among those, nine subtypes of synaptic endings were identified. These differed in their ultrastructural characteristics and distribution in the nucleus and on three cell types analyzed. Four of the subtypes were immunoreactive for glutamate and contained round synaptic vesicles, whereas five were immunoreactive for glycine and/or GABA and contained flattened or pleomorphic synaptic vesicles. The analysis of the distribution of the nine synaptic endings on the cell types revealed that eight distributed on fusiform cells, six on vertical cells and five on cartwheel cells. In addition, postembedding immunogold labeling of the glycine receptor α1 subunit showed that it was present at postsynaptic membranes in apposition to synaptic endings containing flattened or pleomorphic synaptic vesicles and immunoreactive for glycine and/or GABA on the three cells analyzed. This information is valuable to our understanding of the response properties of DCN neurons. J. Comp. Neurol. 477:253–272, 2004. © 2004 Wiley‐Liss, Inc.
Patterns of cell–cell coupling in embryonic spinal cord studied via ballistic delivery of gap‐junction‐permeable dyes
Authors: Bittman Kevin S. , Panzer Jessica A. , Balice‐Gordon Rita J. 
Published: August 2004

AbstractIntercellular communication mediated by gap junctions is developmentally regulated in many tissues, including the nervous system. In rodent lumbar spinal cord, extensive gap junctional coupling among motor neurons innervating the same muscle is present at birth but is no longer present 1 week later. Little is known about how this motor‐pool‐specific coupling arises during embryonic development. To address this question, we developed a novel method of visualizing patterns of cell–cell coupling that can be applied to a wide range of tissues. Gap‐junction‐permeable dyes adsorbed to metal beads were delivered into individual cells in embryonic cerebral cortex or spinal cord using pressure. Dye diffused off of the bead surface into the cytoplasm, crossed gap junctions, and labeled clusters of coupled cells. For embryonic cerebral cortex, this method revealed patterns of cell–cell coupling similar to those reported with other techniques. In embryonic lumbar spinal cord, cell–cell coupling is widespread in the ventricular zone at E11, and the extent of coupling decreases until birth. In the ventral horn, motor neurons are coupled into clusters at E14, with little change in the extent of coupling at E16, and a similar extent of coupling is present at birth. The cell types within clusters, identified by using antibodies against homeodomain transcription factors, were surprisingly heterogeneous in both the ventricular zone and the motor columns. Taken together, these data suggest that the spatial and temporal patterns of cell–cell coupling are dynamic and that cell‐type‐specific gap junctional coupling arises gradually during spinal cord development. J. Comp. Neurol. 480:273–285, 2004. © 2004 Wiley‐Liss, Inc.
Expression and distribution of octopus gonadotropin‐releasing hormone in the central nervous system and peripheral organs of the octopus (Octopus vulgaris) by in situ hybridization and immunohistochemistry
Authors: Iwakoshi‐Ukena Eiko , Ukena Kazuyoshi , Takuwa‐Kuroda Kyoko , Kanda Atshuhiro , Tsutsui Kazuyoshi , Minakata Hiroyuki 
Published: August 2004

AbstractWe recently purified a peptide with structural features similar to vertebrate gonadotropin‐releasing hormone (GnRH) from the brain of Octopus vulgaris, cloned a cDNA encoding the precursor protein, and named it oct‐GnRH. In the current study, we investigated the expression and distribution of oct‐GnRH throughout the central nervous system (CNS) and peripheral organs of Octopus by in situ hybridization on the basis of the cDNA sequence and by immunohistochemistry using a specific antiserum against oct‐GnRH. Oct‐GnRH mRNA‐expressing cell bodies were located in 10 of 19 lobes in the supraesophageal and subesophageal parts of the CNS. Several oct‐GnRH–like immunoreactive fibers were seen in all the neuropils of the CNS lobes. The sites of oct‐GnRH mRNA expression and the mature peptide distribution were consistent with each other as judged by in situ hybridization and immunohistochemistry. In addition, many immunoreactive fibers were distributed in peripheral organs such as the heart, the oviduct, and the oviducal gland. Modulatory effects of oct‐GnRH on the contractions of the heart and the oviduct were demonstrated. The results suggested that, in the context of reproduction, oct‐GnRH is a key peptide in the subpedunculate lobe and/or posterior olfactory lobe–optic gland–gonadal axis, an octopus analogue of the hypothalamo–hypophysial–gonadal axis. It may also act as a modulatory factor in controlling higher brain functions such as feeding, memory, movement, maturation, and autonomic functions. J. Comp. Neurol. 477:310–323, 2004. © 2004 Wiley‐Liss, Inc.
Postnatal development of the cerebellum and the CNS adrenergic system is independent of norepinephrine and epinephrine
Authors: Jin Sung‐Ha , Kim Hyung J.T. , Harris D. Christopher , Thomas Steven A. 
Published: August 2004

AbstractA fundamental question in the formation of the nervous system is the extent to which a neurotransmitter contributes to the development of the neurons that synthesize and release it. A complementary question is whether neurotransmitter signaling contributes to the development of postsynaptic targets. Prior studies have suggested that adrenergic signaling may promote adrenergic neuronal proliferation or survival and may be critical for the postnatal development of the cerebellum. To test these possibilities genetically, we studied mice that are unable to synthesize norepinephrine and epinephrine (NE/E), the endogenous adrenergic receptor ligands, due to a disruption the gene for dopamine β‐hydroxylase. These mice develop postnatally in the absence of NE/E. Here we report that the adrenergic neurons of these mutant mice are present in normal numbers and locations and exhibit typical innervation patterns throughout the central nervous system (CNS), as assessed by immunostaining for tyrosine hydroxylase and the NE transporter. Furthermore, cerebellar cortical development (size, foliation, layering, cell number, and position), which proceeds to a large degree postnatally, is unaltered in the mutants. These results indicate that the fate and innervation pattern of the adrenergic neurons, as well as the development of the cerebellum, do not depend on postnatal signaling by NE/E. The results also suggest that when restoration of adrenergic signaling is performed in this mutant mouse model (by administering a synthetic precursor of NE), reversal of phenotypes is due to the synthesis and release of NE/E from adrenergic terminals that are distributed normally within the CNS. J. Comp. Neurol. 477:300–309, 2004. © 2004 Wiley‐Liss, Inc.
Mechanical Properties of Single Motor Molecules Studied by Three‐Dimensional Thermal Force Probing in Optical Tweezers
Authors: Jeney Sylvia , Stelzer Ernst H. K. , Grubmüller Helmut , Florin Ernst‐Ludwig 
Published: August 2004

AbstractA new method combining three‐dimensional (3D) force measurements in an optical trap with the analysis of thermally induced (Brownian) position fluctuations of a trapped probe was used to investigate the mechanical properties of a single molecule, the molecular motor kinesin. One kinesin molecule attached to the probe was bound in a rigorlike state to one microtubule. The optical trap was kept weak to measure the thermal forces acting on the probe, which were mainly counterbalanced by the kinesin tether. The stiffness of kinesin during stretching and compression with respect to its backbone axis were measured. Our results indicate that a section of kinesin close to the motor domain is the dominating element in the flexibility of the motor structure. The experiments demonstrate the power of 3D thermal fluctuation analysis to characterize mechanical properties of individual motor proteins and indicate its usefulness to study single molecule in general.