bluuebunny/crossref_metadata_2025 huggingface dataset:
Brief communication: Cranial reconstruction of Dryopithecus
Authors: Köhler Meike , Moyà‐Solà Salvador , Alba David M.
Published: August 2002

This paper presents the first three‐dimensional reconstruction of the cranium of the European Miocene ape, Dryopithecus. The reconstruction is based on remains collected from Can Llobateres, Spain (CLI 18000; Dryopithecus laietanus), D. fontani (St. Gaudens), and D. brancoi (Kordos and Begun [1997] Am. J. Phys. Anthropol. 103:277–294). Previously unrecognized facial fragments from CLI 18000 were included in the reconstruction. The result shows that Dryopithecus had a relatively short face, with a rather short and well‐rounded neurocranium. From the lateral perspective, the face is concave at midface, and on the cranium the temporal lines run parallel to each other without forming a sagittal crest. Am J Phys Anthropol 115:284–288, 2001. © 2001 Wiley‐Liss, Inc.
Linking structural variability in long bone diaphyses to habitual behaviors: Foragers from the southern African Later Stone Age and the Andaman Islands
Authors: Stock Jay , Pfeiffer Susan
Published: August 2002

The cross‐sectional distribution of cortical bone in long bone diaphyses is highly responsive to mechanical loading during life, yet the relationship between systemic and localized influences on skeletal structure remains unclear. This study investigates postcranial robustness throughout the body among adults from two groups of foragers with different patterns and modes of mobility, to determine whether there is evidence for upper vs. lower body localization of skeletal robustness. The samples used for this comparison are from the southern African Later Stone Age (LSA; n = 65, male = 33, female = 28) dating from ca. 10,000 to 2,000 B.P., and 19th century indigenous Andaman Islanders (AI; n = 36, male = 17, female = 16). The LSA were highly mobile foragers who did not exploit offshore marine resources. In contrast, the AI had tightly constrained terrestrial, but significant marine, mobility. Geometric properties of cortical bone distribution in the diaphyses of the clavicle, humerus, femur, tibia, and first metatarsal are compared between the samples, providing a representation of skeletal robustness throughout the body. Multivariate ANOVA shows the AI to have significantly stronger clavicles and humeri, while the LSA femora, tibiae, and first metatarsals are stronger than those of the AI. These patterns, in which upper and lower limbs show biomechanical properties that are consistent with habitual behaviors, suggest localized osteogenic response. Although postcranial robustness appears to be correlated with overall limb function, the results suggest that more proximal elements within the limb may be more responsive to mechanical loading. Am J Phys Anthropol 115:337–348, 2001. © 2001 Wiley‐Liss, Inc.
Association studies of multiple candidate genes for Parkinson's disease using single nucleotide polymorphisms
Authors: Momose Yoshio , Murata Miho , Kobayashi Kazuhiro , Tachikawa Masaji , Nakabayashi Yuko , Kanazawa Ichiro , Toda Tatsushi
Published: August 2002

We studied 20 single nucleotide polymorphisms in 18 candidate genes for association with Parkinson's disease. We found that homozygosity for the V66M polymorphism of the brain‐derived neurotrophic factor (BDNF) gene occurs more frequently in patients with Parkinson's disease than in unaffected controls (χ2 = 5.46) and confirmed an association with the S18Y polymorphism of the UCH‐L1 gene. Our results provide genetic evidence supporting a role for BDNF in the pathogenesis of Parkinson's disease.
X‐linked lissencephaly with absent corpus callosum and ambiguous genitalia (XLAG): Clinical, magnetic resonance imaging, and neuropathological findings
Authors: Bonneau Dominique , Toutain Annick , Laquerrière Annie , Marret Stéphane , Saugier‐Veber Pascale , Barthez Marie‐Anne , Radi Sophie , Biran‐Mucignat Valérie , Rodriguez Diana , Gélot Antoinette
Published: August 2002

X‐linked lissencephaly with absent corpus callosum and ambiguous genitalia is a newly recognized syndrome responsible for a severe neurological disorder of neonatal onset in boys. Based on the observations of 3 new cases, we confirm the phenotype in affected boys, describe additional MRI findings, report the neuropathological data, and show that carrier females may exhibit neurological and magnetic resonance imaging abnormalities. In affected boys, consistent clinical features of X‐linked lissencephaly with absent corpus callosum and ambiguous genitalia are intractable epilepsy of neonatal onset, severe hypotonia, poor responsiveness, genital abnormalities, and early death. On magnetic resonance imaging, a gyration defect consisting of anterior pachygyria and posterior agyria with a moderately thickened brain cortex, dysplastic basal ganglia and complete agenesis of the corpus callosum are consistently found. Neuropathological examination of the brain shows a trilayered cortex containing exclusively pyramidal neurons, a neuronal migration defect, a disorganization of the basal ganglia, and gliotic and spongy white matter. Finally, females related to affected boys may have mental retardation and epilepsy, and they often display agenesis of the corpus callosum. These findings expand the phenotype of X‐linked lissencephaly with absent corpus callosum and ambiguous genitalia, may help in the detection of carrier females in affected families, and give arguments for a semidominant X‐linked mode of inheritance.
P0 protein is a target antigen in chronic inflammatory demyelinating polyradiculoneuropathy
Authors: Yan Wei Xing , Archelos Juan J. , Hartung Hans‐Peter , Pollard John D.
Published: August 2002

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is widely regarded as an autoimmune disorder, although the autoantigen remains unknown. In this study, the sera of 21 CIDP patients were examined by immunofluorescence for antimyelin activity and by Western blotting for binding to myelin proteins. Six sera contained anti‐P0 immunoglobulin G antibodies, and four of these caused conduction block and demyelination following intraneural injection in experimental animals. Absorption with P0 protein eliminated the demyelinating activity. These results show that P0 is an autoantigen in some patients with CIDP. Since P0 possesses powerful adhesion properties and is largely responsible for myelin compaction, the demonstration of demyelination by human anti‐P0 antibodies provides new insight into this important and common immunopathological process.
Pure representational neglect after right thalamic lesion
Authors: Ortigue Stéphanie , Viaud‐Delmon Isabelle , Annoni Jean‐Marie , Landis Theodor , Michel Christoph , Blanke Olaf , Vuilleumier Patrik , Mayer Eugène
Published: August 2002

After a right thalamic stroke, an 86‐year‐old man presented an acute pure left representational neglect in the absence of any perceptual neglect. On spatial mental imagery tasks, the patient systematically omitted items located on his left side, but only when a vantage point was given. This suggests that (1) pure representational neglect is not just a residual finding after recovery from global (perceptual and representational) neglect; (2) space representation can be coded by two independent processes: in viewer‐centered or world‐based (allocentric) coordinates; and (3) the right thalamus serves as a relay in the processing of spatial visual imagery.
Early onset multisystem mitochondrial disorder caused by a nonsense mutation in the mitochondrial DNA Cytochrome C oxidase II gene
Authors: Campos Yolanda , García‐Redondo Alberto , Fernández‐Moreno Miguel A. , Martínez‐Pardo Mercedes , Goda Guillermo , Rubio Juan C. , Martín Miguel A. , Del Hoyo Pilar , Cabello Ana , Bornstein Belen , Garesse Rafael , Arenas Joaquín
Published: August 2002

We report the first nonsense mutation (G7896A) in the mtDNA gene for subunit II of cytochrome c oxidase (COX) in a patient with early‐onset multisystem disease and COX deficiency in muscle. The mutation was heteroplasmic in muscle, blood, and fibroblasts from the patient and abundantly present in COX‐deficient fibers, but less abundant in COX‐positive fibers; it was not found in blood samples from the patient's asymptomatic maternal relatives. Immunoblot analysis showed a reduced concentration of both COX II and COX I polypeptides, suggesting impaired assembly of COX holoenzyme.
Fluoxetine modulates motor performance and cerebral activation of patients recovering from stroke
Authors: Pariente Jérémie , Loubinoux Isabelle , Carel Christophe , Albucher Jean‐François , Leger Anne , Manelfe Claude , Rascol Olivier , Chollet François
Published: August 2002

In order to determine the influence of a single dose of fluoxetine on the cerebral motor activation of lacunar stroke patients in the early phase of recovery, we conducted a prospective, double‐blind, crossover, placebo‐controlled study on 8 patients with pure motor hemiparesia. Each patient underwent two functional magnetic resonance imaging (fMRI) examinations: one under fluoxetine and one under placebo. The first was performed 2 weeks after stroke onset and the second a week later. During the two fMRI examinations, patients performed an active controlled motor task with the affected hand and a passive one conducted by the examiner with the same hand. Motor performance was evaluated by motor tests under placebo and under fluoxetine immediately before the examinations to investigate the effect of fluoxetine on motor function. Under fluoxetine, during the active motor task, hyperactivation in the ipsilesional primary motor cortex was found. Moreover, fluoxetine significantly improved motor skills of the affected side. We found that a single dose of fluoxetine was enough to modulate cerebral sensory‐motor activation in patients. This redistribution of activation toward the motor cortex output activation was associated with an enhancement of motor performance.
Irreversible brain creatine deficiency with elevated serum and urine creatine: A creatine transporter defect?
Authors: Cecil Kim M. , Salomons Gajja S. , Ball William S. , Wong Brenda , Chuck Gail , Verhoeven Nanda M. , Jakobs Cornelis , DeGrauw Ton J.
Published: August 2002

Recent reports highlight the utility of in vivo magnetic resonance spectroscopy (MRS) techniques to recognize creatine deficiency syndromes affecting the central nervous system (CNS). Reported cases demonstrate partial reversibility of neurologic symptoms upon restoration of CNS creatine levels with the administration of oral creatine. We describe a patient with a brain creatine deficiency syndrome detected by proton MRS that differs from published reports. Metabolic screening revealed elevated creatine in the serum and urine, with normal levels of guanidino acetic acid. Unlike the case with other reported creatine deficiency syndromes, treatment with oral creatine monohydrate demonstrated no observable increase in brain creatine with proton MRS and no improvement in clinical symptoms. In this study, we report a novel brain creatine deficiency syndrome most likely representing a creatine transporter defect. Ann Neurol 2001;49:401–404
α‐Amino acid: an effective ligand for asymmetric catalysis of transfer hydrogenation of ketones
Authors: Ohta Tetsuo , Nakahara Shu‐ichi , Shigemura Yasuhiko , Hattori Kouichi , Furukawa Isao
Published: August 2002

Ruthenium complexes, prepared by mixing the potassium salt of α‐amino acids and [RuCl2(arene)]2, acted as catalysts for the asymmetric transfer hydrogenation of ketones from 2‐propanol in the presence of KOH. For example, the transfer hydrogenation of acetophenone from 2‐propanol was catalyzed effectively by the ruthenium complex prepared from potassium L‐prolinate and [RuCl2(p‐cymene)]2 to give (R)‐1‐phenylethanol in 72% yield with 81% ee. The yields and enantioselectivities of the product were influenced strongly by the structure of the α‐amino acidate ligand, arene ligand, and substrate, by the amount of additional base, and by the concentration of the substrates. The best enantiomeric excesses of the products was 92%, when 1‐tetralone was subjected to this reaction using a prolinated ruthenium complex bearing p‐cymene. Furthermore, the potassium salts of dipeptides were tested as a ligand for this transfer hydrogenation. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of SiC and Si3N4coatings synthesized by means of inductive thermal plasma from disilane precursors
Authors: Bouyer E. , Schiller G. , Müller M. , Henne R. H.
Published: August 2002

The synthesis of SiC (and/or Si3N4) in an inductive thermal plasma from liquid disilane precursor is described in this paper. One goal of the process presented hereafter is the valorization of a liquid disilane fraction, which is a by‐product of the silicone industry. The liquid precursor is atomized in the core of the thermal inductive plasma and decomposed in the high‐temperature zone. The coating grows on the substrate according to the thermal plasma chemical vapor deposition (CVD) process. The resulting synthesized materials are investigated by means of X‐ray diffraction, scanning and transmission electron microscopy, and nuclear magnetic resonance. The composition of the material synthesized is studied as a function of process parameters, such as the plasma gas nature and its composition, the atomization gas flow rate and the plasma reactor pressure. Control over the composition of the synthesized material composition, as well as the coating microstructure, can be achieved by an appropriate adjustment of the experimental parameters. Nanostructured α/β‐SiC and α/β‐Si3N4can be synthesized successfully with such a thermal plasma process. The deposition rate reached with such a technology is more than 20 μm min−1, which is two to three orders of magnitude higher than that of the conventional CVD method. Copyright © 2001 John Wiley & Sons, Ltd.
The effect of soil properties on cadmium bonds to organic substances of spinach biomass
Authors: Pavlíková Daniela , Pavlík Milan , Vašíčková Soña , Száková Jiřina , Tlustoš Pavel , Vokáč Karel , Balík Jiří
Published: August 2002

The main objective of this study was focused on sequential fractionation of spinach biomass, partial characterization of cadmium‐binding compounds and determination of the cadmium concentration in these fractions. Spinach was cultivated after application of sewage sludge on two soils of different properties and total cadmium content in a model pot experiment. Two non‐polar solvents (light petroleum and ethyl acetate), a polar solvent (methanol) and two solvent mixtures (methanol + H2O & H2O and methanol + H2O + HCl) were used in the extraction series. Isolated fractions were characterized by IR spectroscopy. The lower weight of light petroleum (aliphatic hydrocarbons), ethyl acetate (fatty acids), and methanol (carboxylic acids, mainly acids of citric cycle, pyrrole substances) fractions in sludge treatments compared with the controls showed that the metabolism of plant natural products was inhibited by toxins from sludge. The weight of methanol fraction was dominant for all treatments. The cadmium determined in these fractions was low. The majority of cadmium was found in the methanol + H2O & H2O (oligopeptides, mainly phytochelatins, extractable polypeptides, proteins) and methanol + H2O + HCl (compounds isolated from cell walls and cytoskeleton after hydrolysis) fractions. The effect of toxin stress only appears to be on the quantity of substances, as there is no qualitative change observed in the isolated fractions (measured values of IR spectra bands did not differ for treatments tested). The application of sequential analysis for spinach biomass extraction makes it possible to investigate the complex effects of cadmium and other toxins on plant metabolism. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of chitosan/poly(acrylic acid) polyelectrolyte complex
Authors: Nge Thi Thi , Yamaguchi Makiko , Hori Naruhito , Takemura Akio , Ono Hirokuni
Published: August 2002

Polyelectrolyte complex based on chitosan and acrylic acid monomer by photoinitiated free‐radical polymerization in the absence of crosslinker showed a large transition in swelling in response to changes in pH of surrounding medium. Their ability to swell arises from polyelectrolyte interactions and molecular structure of the complex. The main properties of interest that related to the molecular structure, swelling volumes, glass transition temperature, and elastic modulus of the complex were investigated. The effect of water content, the only variable in the sample component, played an important role in molecular structure of the complex and as a consequence, the extent of intermolecular linkage, especially amide bonds which in turn governed the degree of swelling of the polyelectrolyte complex in this study. The decreased degree of swelling and higher temperature shift of glass transition temperature was found with increased water content, whereas increased modulus of elasticity of dry complex was found in lower water content of synthesis component. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1025–1035, 2002
Influence of temperature, molecular weight, and molecular weight dispersity on the surface tension of polystyrene, polypropylene, and polyethylene. II. Theoretical
Authors: Demarquette Nicole Raymonde , Moreira José Carlos , Shimizu Renato Norio , Samara Mazen , Kamal Musa R.
Published: August 2002

Experimental data for the surface tension of polystyrenes of different molecular weights (3400–200,000) and different molecular weight dispersities (1–3) and of different polyolefins are compared with the predictions of the Patterson–Rastogi and Dee–Sauer cell theories, which infer the surface tension from pressure–volume–temperature (PVT) data. PVT data for these polymers were obtained from the literature and experimentally and are fitted to the Flory–Orwoll–Vrij equation of state. Both theories predict that the surface tension will decrease linearly with increasing temperature and increase with molecular weight, thereby corroborating the experimental data. However, both theories underestimate the entropy change in the surface formation per unit area at a constant volume for low molecular weight and polydisperse systems and underestimate the effect of molecular weight dispersity on surface tension. Both theories feature two parameters, m and b, that quantify the enthalpic and entropic contributions to surface tension. The theoretical predictions are fitted to the experimental data for monodisperse polystyrene (with a molecular weight above the molecular weight of entanglement), polypropylene, and linear low‐density polyethylene to quantify the enthalpic contribution to surface tension. b is then evaluated as a function of molecular weight and molecular weight dispersity and is found to decrease with increasing molecular weight and to increase with increasing molecular weight dispersity, showing that end‐group excess at the surface has some effect on surface tension. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2201–2212, 2002
Uniform‐sized clenbuterol molecularly imprinted polymers prepared with methacrylic acid or acrylamide as an interacting monomer
Authors: Masci Giancarlo , Aulenta Francesca , Crescenzi Vittorio
Published: August 2002

Clenbuterol molecularly imprinted polymer microbeads were prepared with a two‐step swelling and thermal polymerization technique with either methacrylic acid or acrylamide (AAm) as the monomer and ethylene glycol dimethacrylate as the crosslinker at different monomer/crosslinker ratios. The quality of the microbeads, in terms of shape, size distribution, rigidity, and monomer incorporation, was evaluated as a function of the reaction parameters. A good imprinting effect was obtained with both systems, as assessed by high‐performance liquid chromatography (HPLC) experiments with phosphate‐buffered saline/acetonitrile eluents, with a complete baseline separation of clenbuterol with respect to other β‐adrenergic agents obtained. When AAm was used as the monomer, improved control of the polymerization process was achieved, producing microbeads with lower polydispersity and no lack of separation capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2660–2668, 2002
Coloring of radiation damages in ion‐implanted poly(aryl ether ether ketone): LiCl uptake and thermal desorption
Authors: Červená J. , Vacík J. , Hnatowicz V. , Švorčík V. , Kobayashi Y.
Published: August 2002

Poly(aryl ether ether ketone) (PEEK) films irradiated with 2 MeV O+ and Ar+ ions to fluences in the range 1011–1013 cm−2 were treated with 5 mol/L LiCl aqueous solution at 100°C for 1 h. After removal of excessive, weakly bound LiCl the samples were annealed at temperatures from 50 to 250°C for 1 h to check the mobility of the incorporated LiCl. The amount of incorporated LiCl and its depth profile were determined using the neutron depth‐profiling (NDP) technique, which makes use of the 6Li(nth, 4He) 3H nuclear reaction. Up to the maximum annealing temperature no significant escape of the LiCl was observed. With increasing annealing temperature, a gradual migration of LiCl dopant toward the sample surface was observed on the irradiated PEEK samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2780–2784, 2002; DOI 10.1002/app.10253
SEM study of the growth of electrochemically obtained polythiophene thin films: Effect of electrolyte and monomer concentration in acetonitrile
Authors: Ugalde L. , Bernede J. C. , Del Valle M. A. , Díaz F. R. , LeRay P.
Published: August 2002

The initiation of the electrochemical growth of polythiophene thin films was studied by X‐ray photoelectron spectroscopy (XPS), electron probe micro analysis (EPMA), and mainly by scanning electron microscopy (SEM). The films were deposited on SnO2‐coated glass in a classical three‐electrode cell. Depositions were done under pure argon atmosphere. Two electrolytes were tested, tetrabutyl ammonium hexafluorophosphate (Bu4NPF6) and tetramethylammonium hexafluorophosphate (Me4NPF6) in anhydrous acetonitrile. The effect of the electrolyte, and monomer and electrolyte concentration, on the film properties were visualized. These results are discussed with the help of the other characterization techniques. It is shown that for optimum concentration (0.05M monomer and 0.05M electrolyte), two processes are active, one three‐dimensional (3D) and one two‐dimensional (2D). When the monomer concentration is increased, a third 3D contribution is presently active. When the electrolyte concentration increases, there is some electrolyte crystal precipitation on the synthesized polymer films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1799–1809, 2002; DOI 10.1002/app.10291
Natural rubber–ethylene‐propylene‐diene rubber covulcanization: Effect of reinforcing fillers
Authors: Kumar Arup , Dipak Ghosh , Basu Kumar
Published: August 2002

Filled covulcanizates of elastomer blend comprising natural rubber (NR) and ethylene‐propylene‐diene rubber (EPDM) of commercial importance were successfully prepared by using a multifunctional rubber additive; namely, bis(diisopropyl)thiophosphoryl disulfide (DIPDIS). A Two‐stage vulcanization technique further improved the physicochemical properties of the blend vulcanizates by restricting, through the formation of polar rubber bound intermediates, the migration of curative and filler from lower to highly unsaturated rubber. Scanning electron microscopy studies indicate homogeneity and coherency in the morphology of the two‐stage vulcanizates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1001–1010, 2002; DOI 10.1002/app.10361
Solubilization of nitrogen‐containing heterocyclic compounds in reactive solvents
Authors: Kucharski Mieczysław , Głowacz‐Czerwonka Dorota
Published: August 2002

A reactive solvent was obtained by reacting 1 mol of cyclohexanone with 5 mol of formaldehyde. The structure of the solvent was studied by using 1H‐NMR and IR spectroscopy. It was used for solubilization of melamine and other heterocyclic compounds containing NH groups, such as adenine, carbazole, cytozine, guanine, thymine, and uracyl, as well as isocyanuric, barbituric, and uric acids. The solubilization involved the reaction of formaldehyde (liberated at an elevated temperature) with amino groups of the compound. Melamine was the compound with the best solubility in the reactive solvent. Preliminary attempts of curing the solutions have also been made. The oligomers cured at 120°C in the presence of acidic catalysts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2650–2659, 2002
Reactive surfactants in heterophase polymerization. XVII. Influence of the surfactant on the mechanical properties and hydration of the films
Authors: Gauthier C. , Sindt O. , Vigier G. , Guyot A. , Schoonbrood H. A. S. , Unzue M. , Asua J. M.
Published: August 2002

In the context of a European union‐supported network on “Reactive Surfactants for Heterophase Polymerization,” different polymerizable surfactants (surfmers) have been synthesized and engaged in the emulsion polymerization of styrene, butyl acrylate, and acrylic acid. The thermomechanical properties of films cast from these different latices are reported in this article. The evolution of the mechanical properties with temperature and the effect of water molecules on these properties are studied. We observed that the studied surfactants do not influence the properties of the dry films. However, some differences due to grafting of reactive surfactants appeared when the films were wet. The amount of water uptake is drastically decreased when only reactive surfactants are present in the film. Concerning the mechanical behavior of the wet films, a decrease of the plastic flow stress is observed for all the samples whatever the nature of the surfactant (reactive or conventional). Hence, calorimetric measurements and dynamic mechanical analysis are used to identify the possible mechanisms that induce the change in the mechanical behavior of the latex films. In the case of reactive surfactant grafted to the polymer, the very low value of water uptake is accompanied by a plasticization of the polymer. In contrast, no plasticizing effect is observed in the case of nonreactive surfactant, even if the amount of water is very large. Finally, the tensile behavior of the styrene–butyl acrylate copolymer versus temperature is analyzed in the frame of the quasi point defects (qpd) model. Both rubber elasticity and chain orientation effects are taken into account to describe the behavior laws at large extensions (i.e., ϵ ≈ 1.2). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1686–1700, 2002; DOI 10.1002/app.10548
Kinetics and mechanism of grafting of crotonic acid onto acrylonitrile–butadiene–styrene terpolymer
Authors: Zhou Z. F. , Huang H. , Liu N. C.
Published: August 2002

The grafting of crotonic acid onto acrylonitrile‐butadiene‐styrene terpolymer (ABS) was initiated by benzoyl peroxide (BPO) in 1,2‐dichloroethane solution. The infrared spectra confirmed that crotonic acid was successfully grafted onto ABS backbone. The influences of the concentration of crotonic acid, BPO, and ABS on grafting were studied. The graft occurred at the butadiene region of ABS. A reaction mechanism was proposed: the grafting most likely took place by cross‐termination of poly(crotonic acid) radicals with ABS macroradicals. The initial rate of grafting could be written as: Rp = 2.02 × 10−4[P][M] 2[I2]0.5/([M] + 1.05[P])2. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 726–733, 2002
Epoxidized natural rubber as a reinforcement modifier for silica‐filled nitrile rubber
Authors: George K. Mariamma , Varkey Jacob K. , Thomas K. T. , Mathew N. M.
Published: August 2002

Hydrated silicas impart better physical properties to polar rubbers, compared to those of hydrocarbon rubbers. However, to achieve optimum properties silane coupling agents are crucial in such formulations. Epoxidized natural rubber (ENR) in small proportions is used as a reinforcement modifier for silica‐filled nitrile rubber (NBR). Two systems of cure were used: N‐cyclohexyl‐ 2‐benzthiazyl sulfenamide (CBS) alone and in combination with diphenyl guanidine (DPG). In the CBS accelerated system, incorporation of an optimum concentration of about 15% of ENR on total rubber was found to improve technological properties. Addition of a secondary accelerator further improves these properties. Comparable results are obtained with those containing coupling agent and NBR–ISAF. High bound rubber and volume fraction values indicate a high polymer–filler interaction and gel content resulting from the NBR–ENR interaction. Results of this study reveal that ENR could be used as a reinforcement modifier for the NBR–silica system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 292–306, 2002
Biodegradable polyester composites reinforced with short abaca fiber
Authors: Shibata Mitsuhiro , Takachiyo Kei‐Ichiro , Ozawa Koichi , Yosomiya Ryutoku , Takeishi Hiroyuku
Published: August 2002

The mechanical properties of poly(3‐hydroxybutyrate‐ co‐3‐hydroxyvarelate) (PHBV) composites, reinforced with short abaca fibers prepared by melt mixing and subsequent injection molding, were investigated and compared with PHBV composites reinforced with glass fiber (GF). The influences of fiber length, fiber content, and surface treatment of the natural fiber on the mechanical properties were evaluated. Regarding fiber length, the tensile properties had a maximum at a fiber length of about 5 mm. The flexural properties of the PHBV/abaca composite were improved by the surface treatment of abaca with butyric anhydride and pyridine for 5 h because of the increase of interfacial adhesiveness between the matrix polyester and the surface‐esterified fiber, as is obvious from the SEM micrographs. The flexural and tensile properties of PHBV/treated abaca composite were comparable to those of PHBV/GF composite, except for tensile modulus, compared with the same weight fraction of fiber. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 129–138, 2002
A novel highly copper(II)‐selective chelating ion exchanger based on poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) beads modified with aspartic acid derivative
Authors: Horák Daniel , Beneš Milan J. , Gumargalieva Klara , Zaikov Guennadi
Published: August 2002

Anchoring the hydroxyaspartic acid onto poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) (poly(GMA‐co‐EDMA)) beads or epoxysuccinic acid onto ammonium‐modified poly(GMA‐co‐EDMA) beads resulted in a novel chelating resin, which contained up to 0.37 mmol of the ligand per gram of resin. Batch extraction experiments showed a very high selectivity for Cu2+ over Zn2+ and Cd2+ ions in buffered solutions under competitive conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 913–916, 2001
Studies on the strength and wear resistance of tetrapod‐shaped ZnO whisker–reinforced rubber composites
Authors: Zhou Zuowan , Liu Shikai , Gu Lixia
Published: August 2002

Zinc oxide whisker with a tetrapod shape was treated with a coupling agent using an orthogonal design and was mixed into the substrate of natural rubber to obtain the composites. The results of the experimental tests show that the tensile strength of the composites progressively increases with an increased amount of the related whisker. The experiments also indicate that the rubber reinforced by the tetrapod‐shaped ZnO whisker is distinct isotropy. The wear tests demonstrate that the composites containing ZnO whisker appear to have good wear‐resistance behavior. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1520–1525, 2001
Calculation of alcohol‐acetone‐cellulose acetate ternary phase diagram and their relevance to membrane formation
Authors: Hao Ji Hua , Wang Shichang
Published: August 2002

ABSTRACT

Alcohol‐acetone‐cellulose acetate phase diagrams incorporated with methanol, ethanol, and isopropanol as nonsolvents are calculated according to a new form of the Flory–Huggins equation. Nonsolvent–cellulose acetate interaction parameters are measured by swelling experiments. Concentration‐dependent nonsolvent–solvent interaction parameters are obtained by vapor–liquid equilibrium and the Wilson equation. It is shown that alcohol is a week coagulant compared with water, and water > methanol > ethanol > isopropanol for cellulose acetate. The phase diagrams characteristic of acetone‐cellulose acetate combined with water, methanol, ethanol, and isopropanol as nonsolvents is different, which leads to the different morphological structure of a cellulose acetate membrane. The structure of a water coagulated membrane has large macrovoids from liquid–liquid phase separation. A methanol coagulated membrane has a honeycomb‐like structure from spinodal microphase separation. An ethanol or isopropanol coagulated membrane has a thicker, dense top layer from the delay time phase separation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1650–1657, 2001
Preparation and characterization of nanofiltration composite membranes using polyacrylonitrile (PAN). I. preparation and modification of PAN supports
Authors: Oh Nam‐Wun , Jegal Jonggeon , Lee Kew‐Ho
Published: August 2002

Polyacrylonitrile (PAN) supports useful for the formation of nanofiltration (NF) composite membranes were prepared from PAN solutions in N‐methylpyrrolidone (NMP), using a phase‐inversion method. The compositions of the PAN/NMP solutions used were as follows: 10/90, 15/85, and 20/80 (in wt %). The PAN supports were treated with various concentrations of NaOH aqueous solutions (0.1, 0.5, 1, and 2 mol) for certain periods of times (0.5, 1, 2, and 3 h) in order to modify their surface chemically and morphologically. The characteristics of the supports, modified or unmodified, were carefully studied. The morphology of those were observed with field‐emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The change of the chemical structure of those by the NaOH treatment was studied using FTIR–ATR spectroscopy and ESCA. The permeation properties of those were also determined at 1–5 bar of operation pressure using a PEG 35,000 aqueous feed solution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1854–1862, 2001
Thermodynamic work of adhesion and peel adhesion energy of dimethoxysilyl‐terminated polypropylene oxide/epoxy resin system jointed with polymeric substrates
Authors: Okamatsu Takahiro , Yasuda Yushiro , Ochi Mitsukazu
Published: August 2002

The characterization of the interfacial surface of a dimethoxysilyl‐terminated polypropylene oxide (DMSi–PPO)/diglycidylether of bisphenol A (DGEBA) system, which has the phase structure of DGEBA particles in a DMSi–PPO matrix, was investigated by using model joints with polymeric substrates. The surface free energy (γ) of the DMSi–PPO/DGEBA system had varied with the γ of each substrate. When the system contacted to low surface free energy materials such as Teflon, polypropylene, and polyethylene, the γ of the system showed about 14.3–31.6 mJ/m2; on the other hand, when the system contacted to high surface free energy substrates such as polyethylene–telephthalate and polyimide, the γ of the system showed 50.4 and 64.6 mJ/m2, respectively, because the concentration of the DGEBA as a polar component in the system changed around these interfaces. In the low surface energy substrates used, the actual peel adhesion energy value was in good agreement with the thermodynamic work of adhesion (Wa) determined independently. However, in the high surface energy materials used, the peel adhesion energies were 103–104 times larger than Wa because the energy was dissipated viscoelastically at the jointed points. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1920–1930, 2001
Ring‐opening polymerization of epichlorohydrin and its copolymerization with other alkylene oxides by quaternary catalyst system
Authors: Xie Hong‐Quan , Guo Jun‐Shi , Yu Guang‐Quan , Zu Jiang
Published: August 2002

An effective quaternary catalyst consisting of trialkyl aluminum, phosphoric acid, electron donor, and water for ring‐opening polymerization of epichlorohydrin (ECH), as well as its copolymerization with ethylene oxide (EO), propylene oxide (PO), and allyl glycidyl ether (AGE) to obtain elastomers, were studied. We investigated the optimum composition for the quaternary catalyst; the character of the catalyst; the reactivity of the four alkylene oxides during homopolymerization and copolymerization; the behavior of ECH, EO, and PO during terpolymerization; and glass transition temperatures of the copolymer and terpolymers. The results showed that the nitrogen‐containing electron donors are suitable as the third component, whereas oxygen‐containing electron donors are not. Water as the fourth component can increase the molecular weight of the homopolymer and copolymers of ECH. According to the polymerizability of tetrahydrofuran with the quaternary catalyst and the reactivity ratios of the four alkylene oxides, the quaternary catalyst was assumed to be of a coordinated anionic type. The reactivity ratios for these four alkylene oxides were determined to be EO > PO > AGE > ECH. They were verified by terpolymerization of ECH, EO, and PO. The glass transition temperature of the terpolymer exhibits a minimum value at nearly 3:1 molar ratio of PO to EO, when the molar ratio of ECH used is constant at the beginning of terpolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2446–2454, 2001
Properties and morphologies of PVC/nylon terpolymer blends
Authors: Lian Yongxiao , Zhang Yong , Peng Zhonglin , Zhang Xiangfu , Fan Ruliang , Zhang Yinxi
Published: August 2002

A new kind of blends of polyvinyl chloride (PVC)/nylon terpolymer was reported in this article. Two compatibilizers were used in this study: one is a terpolymer of ethylene–n‐butyl acrylate–monoxide (EnBACO); the other is terpolymer of EnBACO grafted with maleic anhydride (EnBACO‐g‐MAH). The observation of scanning electron microscope (SEM) reveals that the PVC/nylon terpolymer blends have a two‐phase structure; and the nylon terpolymer phase is the continuous phase, and PVC domains in the PVC/nylon terpolymer/EnBACO‐g‐MAH blends have fine dispersion over a broad range of the PVC/nylon terpolymer ratio. EnBACO‐g‐MAH is more compatible with the nylon terpolymer than EnBACO. EnBACO and EnBACO‐g‐MAH have different effects on the glass transition temperatures of the PVC phase and nylon terpolymer phase in the blends. The notched Izod impact strength, tensile strength, elongation at break, Vicat softening temperature (VST), and melt flow index (MFI) critically depend on PVC/nylon terpolymer ratio, the kinds and concentration of the compatibilizers. The PVC/nylon terpolymer/EnBACO‐g‐MAH blends display a good combination of high toughness, high flowability, and high VST under low load. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2823–2832, 2001
Transport of Cu(II) ions through charged cation‐exchange membranes
Authors: Ersöz M. , Çengeloğlu Y. , Kir E. , Koyuncu M. , Yazicigil Z.
Published: August 2002

Transport of Cu(II) ions through polysulfonated cation‐exchange membranes under Donnan dialysis conditions was studied as a function of the pH gradient. The used charged membranes are homogeneous (polysulfone composition) and heterogeneous (polysulfone with polyester support) structures which are strongly acidic cation‐exchange microporous‐type membranes. The flux increases with decreasing of the pH gradient, which is influenced by the transport of copper ions. The quantitative relations were obtained which describe the time dependence of the transport system with the equilibrium distribution and the results were correlated with the flux data as well as with the membrane structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 421–427, 2001
Thermal fractionation and crystallization enhancement of silane‐grafted water‐crosslinked low‐density polyethylene
Authors: Shieh Yeong‐Tarng , Chen Jui‐Shui , Lin Chung‐Chin
Published: August 2002

Thermal fractionations performed using differential scanning calorimetry (DSC) to characterize the heterogeneities in molecular structures of low‐density polyethylene (LDPE), silane‐grafted LDPE (G‐LDPE), and silane‐grafted water‐crosslinked LDPE with gel fractions of 30 and 70 wt % are reported. In regular DSC analyses, LDPE, G‐LDPE, and the low gel fraction of crosslinked samples (30 wt %) give one broad endothermic peak at ∼110 °C, whereas the high gel fraction of crosslinked samples (70 wt %) give overlapped multiple endothermic peaks in a much broader temperature range. After thermally fractionated in the range 60–145 °C, LDPE, G‐LDPE, and the low gel fraction samples give five to six endothermic peaks in the low‐temperature range, whereas the high gel fraction samples give nine peaks, with three additional peaks appearing in the high‐temperature range. These multiple peaks correspond to fractions of different molecular structures, with the additional peaks for the high gel fraction samples corresponding to the fraction of molecular segments with low or no branching. This fraction of molecular segments is increasingly extruded out of the gel region with increasing gel fraction by crosslinking and leads to an enhancement of crystallization of the sample. This crystallization enhancement behavior is also demonstrated by the X‐ray diffraction data and polarized optical micrographs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 591–599, 2001
Viscoelastic behavior of anhydride‐cured epoxy system initiated by thermal latent catalyst
Authors: Kwak Geun‐Ho , Park Soo‐Jin , Lee Jae‐Rock
Published: August 2002

The thermal latency and viscoelastic behavior during the cure of a new catalytic (N‐benzylpyrazinium hexafluoroantimonate) anhydride‐cured epoxy system were studied with differential scanning calorimetry and a rheometer under isothermal conditions. The gelation time was obtained from the evaluation of the storage modulus, loss modulus, and damping factor. The temperature dependence on the reaction time was described by the Arrhenius expression, and the crosslinking activation energy was determined from the Arrhenius plot based on the gelation time and reaction temperature. The gelation time and crosslinking activation energy characterized from rheological behaviors increased with increasing anhydride composition and showed a maximum value with a mixing ratio of 0.65, which was due to the compact crosslinking network without a side reaction in the ratio. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 646–653, 2001
Differential scanning calorimetry analysis of silicon‐containing and phosphorus‐containing segmented polyurethane. I—Thermal behaviors and morphology
Authors: Lin Ming‐Fung , Shu Yao‐Chi , Tsen Wen‐Chin , Chuang Fu‐Sheng
Published: August 2002

This article investigated thermal transition and morphology utilizing differential scanning calorimetry (DSC), which was performed on silicon‐containing and phosphorus‐containing segmented polyurethane (Si‐PU and P‐PU). The hard segments of those Si‐PU and P‐PU polymers investigated consisted of 4,4′‐diphenylmethane diisocyanate (MDI) and diphenylsilanediol (DSiD), MDI, and methylphosponic (MPA), respectively. The soft segment of those polymers comprised polytetramethylene ether glycol, with an average molecular weight of 1000 or 2000 (PTMG 1000 and PTMG 2000, respectively). Several thermal transitions appeared for on the Si‐PU and P‐PU polymers, reflecting both the soft‐segment and hard‐segment phases. The Si‐PU and P‐PU polymers with a lower hard‐segment content exhibited a high degree of phase separating as indicated by the constancy of both the soft‐segment glass transition temperature (Tgs) and the breadth of transition zone (ΔB). The polymers in which PTMG 2000 was used as the soft segment generally exhibited a crystalline melting endotherm about 10°C, while crystallization usually disappeared upon melt quenching. The hard segments of the Si‐PU and P‐PU polymers displayed multiple endotherms. The first endotherm was related to a short‐range ordering of the hard segment domain (Region I), and the second endotherm was ascribed to a long‐range ordering of the domain (Region II). The wide‐angle X‐ray demonstrated that the structure in Region I and Region II was almost completely amorphous. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3489–3501, 2001
Differential scanning calorimetry analysis of silicon‐containing and phosphorus‐containing segmented polyurethane. II Annealing effect
Authors: Shu Yao‐Chi , Lin Ming‐Fung , Tsen Wen‐Chin , Chuang Fu‐Sheng
Published: August 2002

The effect of thermal annealing on the multiple endothermic behavior and morphological changes in the silicon‐containing and phosphorus‐containing segmented polyurethane (Si‐PU and P‐PU) has been studied by differential scanning calorimetry (DSC). In the amorphous hard segments of the Si‐PU and P‐PU polymers that were annealed below T2, both the T1 temperature, and magnitude of T1 endotherm increased linearly as a function of the logarithmic annealing time (log ta). This result demonstrated that the endothermic behavior (T1 endotherm) is typical of enthalpy relaxation resulting from the physical aging of the amorphous hard segment. Furthermore, the P‐PU polymer was unstable than the Si‐PU polymer due to the fact that the phosphorus‐containing hard segment produce aged more easily. Dissociation of domains and enthalpy relaxation of hard segments for the Si‐PU polymer was associated with T2 endothermic behavior. However, the enthalpy relaxations of the T2 endothermic behavior for P‐PU polymer was absent, which could be attribute to the behavior of degradation in the temperature range of T2 endotherm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3502–3513, 2001
Water stability of syndiotactic poly(vinyl alcohol)/iodine complex film
Authors: Lyoo Won Seok , Yeum Jeong Hyun , Choi Jin Hyun , Song Han‐Chul , Ji Byung Chul , Kim Jae Pil , Noh Tae Hwan , Yoon Woong Jae , Cheong Tae Sik
Published: August 2002

The desorption behavior of iodine in syndiotactic poly(vinyl alcohol) (s‐PVA) with a syndiotactic diad content of 63.1% iodine film in water was investigated in relation to the solubility of s‐PVA in water. Despite a low number‐average degree of polymerization of 900, the degree of solubility of s‐PVA film in water at 80°C was limited to about 10%, whereas atactic poly(vinyl alcohol) (a‐PVA) film was completely soluble at a lower temperature, 50°C. The degree of iodine desorption of s‐PVA/iodine film at a high temperature decreased remarkably compared with that of a‐PVA/iodine film. The fastness of iodine of the drawn s‐PVA/iodine film was far superior to that of the undrawn film. Over a draw ratio of 5, the iodine desorption was suppressed significantly with increasing drawing temperature rather than the draw ratio. In addition, the iodine desorption of postdrawn s‐PVA/iodine film was lower than that of predrawn s‐PVA/iodine film. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 108–113, 2001
Hybrid membranes based on SiO2/polyether‐b‐polyamide: Morphology and applications
Authors: Sforça Maurício L. , Yoshida Inez V. P. , Borges Cristiano P. , Nunes Suzana P.
Published: August 2002

Hybrid materials were prepared incorporating silica networks by the sol–gel process into the poly(amide‐b‐polyether) block copolymer PEBAX®. PEBAX®/silica hybrids were characterized by transmission electron microscopy, atomic force microscopy, differential scanning calorimetry, and X‐ray diffraction. The pervaporation of phenol from dilute aqueous solutions through hybrid membranes was investigated. Films prepared with lower silica contents showed better dispersed inorganic networks and were more selective in the pervaporation of phenol/water solutions. Films prepared with higher silica contents had a clear phase‐separated morphology with lower performance in pervaporation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 178–185, 2001