bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of γ-Irradiation on the Surface and Catalytic Properties of Co3O4/MgO Systems Aged for One Year
Authors: El-Shobaky G.A. , El-Molla S.A. , Ismail S.A. 
Published: May 2003

The effects of γ-rays (20–160 Mrad) on the surface and catalytic properties of two Co3O4/MgO systems were investigated. The formulae of the investigated solids were 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively, both prepared by the impregnation method and calcined at 500°C. The irradiated samples were left for one year in sealed tubes before any measurements were undertaken. γ-Irradiation of the investigated solids resulted in a progressive decrease in the particle size of the Co3O4 and MgO phases. This treatment also led to a measurable increase in the specific surface area of the treated solids to an extent proportional to the γ-ray dosage. Treatment of the Co3O4/MgO system with different doses of γ-rays brought about a significant increase in the catalytic activity expressed both as the reaction rate constant and as the reaction rate constant per unit surface area. However, the curve relating to the catalytic activity and dosage of γ-rays showed maxima located at 40 and 80 Mrad for samples having the formula 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively. Furthermore, samples exposed to 160 Mrad showed a larger catalytic activity than the unirradiated samples. The results demonstrate the role of γ-rays in inhibiting the deterioration of the catalytic activity of the investigated systems as a function of aging time. The irradiation process did not modify the activation energy of the catalyzed reaction but altered the concentration of active centres on the surfaces of the solids without changing their energetic nature.
Activated Carbons Prepared from Pine Wastes for the Uptake of Organic Compounds from Aqueous Solution
Authors: García-García A. , Gregório A. , Boavida D. , Gulyurtlu I. 
Published: May 2003

The feasibility of preparing chemically-activated carbons from a char obtained by the gasification of pine wastes has been studied. The optimised conditions for producing activated carbons with well-developed porosity were investigated and the influence of activating agent (KOH)/char ratio, temperature and duration of the pyrolysis process established. Additionally, for comparative purposes, two different designs for the stainless-steel basket in which the sample to be activated was inserted were tested in selected cases to determine the quality of the activated carbons produced. The results obtained showed that micropore development depended strongly on the KOH/char ratio, which was the most important variable under the conditions studied. The activated carbon with the largest adsorption capacity produced had a well-developed porosity, providing a total micropore volume of 0.678 cm3/g and an apparent surface area (as estimated by the DR method) of 1908 m2/g. The activated carbons prepared exhibited high benzene adsorption rates that increased with increasing micropore volume. The initial adsorption coefficient (γ) appeared to correlate strongly with the micropore volume deduced from nitrogen adsorption data.
Mechanical performance of blends of thermotropic liquid crystalline polymer spheres‐dispersed polycarbonate
Authors: Xue Yongfu , Zhang Jun , Zheng Xuejing , He Jiasong 
Published: May 2003

AbstractLiquid crystalline polymer (LCP) blends with a thermotropic LCP dispersed in the form of microspheres is studied to show the role of LCP spheres. Polycarbonate (PC), p‐hydroxybenzoic acid–poly(ethylene terephthalate) copolyester, and random styrene–maleic anhydride copolymer are used as the matrix, the dispersed phase, and the compatibilizer, respectively. A scanning electron microscopy observation shows the formation of LCP spheres with improved interfacial adhesion in the injection‐molded samples via compatibilization. The mechanical tests show increased modulus, elongation at break, and fracture‐absorbed energy of blends of LCP spheres‐dispersed PC. This shows an optimistic potential for the dispersed LCP phase, in spite of its morphology in the form of fibrils for reinforcing the matrix or in the form of microspheres for toughening the matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1493–1499, 2003
Photopolymerization kinetics of hyperbranched acrylated aromatic polyester
Authors: Kou Huiguang , Asif Anila , Shi Wenfang 
Published: May 2003

AbstractThe influences of the irradiation temperature, comonomer content, sample thickness, and photoinitiator concentration on the polymerization kinetics of hyperbranched acrylated aromatic polyester (HAAPE) were investigated with photo‐differential scanning calorimetry and IR measurements. The maximum photopolymerization rate increased with the temperature rising up to 110°C but decreased beyond 110°C. An activation energy of 16 kJ mol−1 for the photopolymerization was obtained below 110°C from an Arrhenius plot, but it was negative beyond 120°C. A remarkable synergistic effect between HAAPE and the comonomer trimethylolpropane triacrylate with a molar fraction of around 0.4 was observed from a photopolymerization kinetic study of the resins. The final unsaturation conversion in an ultraviolet‐cured film decreased with the sample thickness, and this became more remarkable as the photoinitiator concentration increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1500–1504, 2003
Fabrication of Ag nanoparticle–encapsulating multilayer films based on PAMAM dendrimers with covalent interlayer linkages
Authors: Luo Yufei , Li Yuan , Jia Xinru , Yang Huaquan , Yang Ling , Zhou Qifeng , Wei Yen 
Published: May 2003

AbstractAg‐dendrimer nanoclusters were prepared with Ag+ and carboxyl shell (G4.5) poly(amino amine) dendrimers. Self‐assembly photosensitive ultrathin films were then fabricated with these Ag‐dendrimer nanoclusters as polyanions and diazoresin (DR) as polycation. With UV irradiating the films became stable because of the formation of covalent linkages between the layers. Compared to similar films containing no Ag nanoclusters, the obtained films showed greatly enhanced electric conductivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1515–1519, 2003
Synthesis of copolymers containing opposite charged comonomers and their interactions with metal ions
Authors: Rivas Bernabé L. , Pereira Eduardo D. 
Published: May 2003

AbstractRadical polymerization was used to synthesize three copolymers of [3‐(methacryloylamino)propyl]trimethylammonium chloride and methacrylic acid [P(MPTA‐co‐MA)]; three copolymers of MPTA and 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid [P(MPTA‐co‐APSA)], which had different feed monomer mole ratios but a constant total number of moles (0.03 mol); and the homopolymers poly(MPTA), poly(MA), and poly(APSA). The yields for all homopolymers and copolymers were over 70 and 90%, respectively. All products were dissolved in water, purified, and fractioned by an ultrafiltration membrane with different exclusion limits of the molecular weight (3,000, 10,000, 30,000, and 100,000 g mol−1). All fractions were lyophilized. The polymeric materials were characterized by FTIR and 1H‐NMR spectroscopy. The metal ion interaction with the hydrophilic polymers was determined as a function of the pH and the filtration factor. It was dependent on the pH, type of ligand group, and charge of the metal ion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1715–1721, 2003
Copper(II) removal from aqueous solution by organosolv lignin and its recovery
Authors: Acemioǧlu B. , Samil A. , Alma M. H. , Gundogan R. 
Published: May 2003

AbstractIn this study the removal of Cu(II) ions from aqueous solution was performed at different concentrations, temperatures, and pHs using ethanol‐based organosolv lignin as the adsorbent. The results indicated that the amount of Cu(II) ions adsorbed onto the lignin increased with increasing concentration and pH; however, it decreased with an increase in temperature. It was possible to remove 40.74% (maximum removal) of Cu(II) ions from aqueous solution by using organosolv lignin within 10 min under certain conditions (3 × 10−4 M and 20°C). The adsorption process was determined to be consistent with the Freundlich isotherm. Furthermore, it was found that 40% (maximum recovery) of the Cu(II) ions adsorbed on the organosolv lignin could be recovered using HCl with an initial concentration of 3 × 10−4 M and a contact time of 10 min. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1537–1541, 2003
Purification of immunoglobulin G from human plasma by metal‐chelate affinity chromatography
Authors: Özkara Serpil , Yavuz Handan , Denizli Adil 
Published: May 2003

AbstractA new group of specific‐affinity beads with metal chelates as ligands and synthetic polymer beads as support matrices was prepared and tested. This study focused on developing metal‐chelated poly(hydroxyethyl methacrylate) (PHEMA) gel beads in a spherical form (100–150 μm in diameter) for the separation of immunoglobulin G (IgG) from human plasma. Crosslinked PHEMA gel beads were prepared by suspension polymerization. The metal‐complexing ligand L‐histidine was then immobilized by covalent binding onto these gel beads. Different transition‐metal ions, including Zn(II), Ni(II), Co(II), and Cu(II), were chelated on these gel beads. An elemental analysis of immobilized L‐histidine for nitrogen was estimated to be 401.9 μmol of L‐histidine/g of PHEMA. The nonspecific IgG adsorption onto plain PHEMA gel beads was negligible (ca. 0.17 mg/g). Higher adsorption values (up to 3.5 mg/g) were obtained in which L‐histidine‐immobilized PHEMA gel beads were used from aqueous solutions. A remarkable increase in the IgG adsorption capacities were achieved from human plasma with L‐histidine‐immobilized gel beads (up to 44.8 mg/g). Further increases in the IgG adsorption capacities of the metal‐chelated gel beads were observed when human plasma was used (up to 79.6 mg/g). The metal‐chelate affinity gel beads allowed the one‐step separation of IgG from human plasma. The recognition range of metal ions for surface histidines from human plasma followed this order: Cu(II) > Ni(II) > Zn(II) > Co(II). IgG molecules could repeatedly be adsorbed and desorbed with these metal‐chelated PHEMA gel beads without a noticeable loss in their IgG adsorption capacity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1567–1572, 2003
Effect of temperature and pressure treatment on the porosity of expanded polytetrafluoroethylene films
Authors: Hall Peter J. , Hitchman Michael J. , Brown Stephen D. , Calo Joseph M. 
Published: May 2003

AbstractSmall‐angle neutron scattering was performed on a series of expanded polytetrafluoroethylene membranes that were subjected to thermal treatment at a maximum of 320°C at pressures up to 517 kPa. The scattering data indicate the existence of monodisperse pores of 2.7‐Å radius, and a polydisperse set of scatterers with surface fractal properties. The thermal treatment had no significant effect on the structure, given that the maximum temperature was below the softening point of the polymer. The effect of increasing pressure was to increase the fractal dimension and to decrease the porosity void fractions. A linear relationship was noted between the Porod invariant values and the applied pressure. The pressure treatment had no effect on the size of the 2.7‐Å pores. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1579–1582, 2003
Preparation and characterization of H4SiMo12O40/poly(vinyl alcohol) fiber mats produced by an electrospinning method
Authors: Gong Jian , Li Xiang‐Dan , Ding Bin , Lee Douk‐Rae , Kim Hak‐Yong 
Published: May 2003

AbstractFor the first time, high‐percentage molybdosilicic acid fiber mats (20–80% H4SiMo12O40) were prepared using the electrospinning technique. The fiber mats were characterized by IR, XRD, and DSC. The results indicated that poly(vinyl alcohol) was changed from a semicrystalline to an amorphous state with an increasing molybdosilicic acid content. The results from scanning electron microscopy (SEM) showed that the average diameter of the fibers was about 285–600 nm. The effects of the viscosity and conductivity of the H4SiMo12O40/poly(vinyl alcohol) solution on the morphologies of the fiber mats were investigated. The swelling properties of the fiber mats in water were also studied.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1573–1578, 2003
Syndiotactic polystyrene‐b‐atactic polypropylene block copolymer alloy as a compatibilizer for syndiotactic polystyrene/isotactic polypropylene blends
Authors: Chen Rui , Wu Qing , Zhu Fangming , Lin Shangan 
Published: May 2003

AbstractA polymeric alloy (SP–A) containing syndiotactic polystyrene (sPS), atactic polypropylene (aPP), and about 66 wt % sPS‐b‐aPP diblock copolymer, was prepared by the sequential feed of monomers in the presence of the half‐titanocene Cp*Ti(OBz)3 (where Cp* is C5Me5 and Bz is PhCH2), modified methylaluminoxane, and external triisobutylaluminum. The effects of the SP–A alloy as a compatibilizer for sPS and isotactic polypropylene (iPP) blends were evaluated. The blending of sPS and iPP, with and without SP–A, was performed in a single‐screw miniextruder with a side channel that allowed the continuous recycling of materials. The influence of SP–A on the mechanical and thermal properties of the immiscible sPS/iPP blends was investigated over a range of composition. The presence of the SP–A alloy resulted in a significant improvement of the impact strength of the blends compared with that of pure sPS and their pure blends. This improvement was particularly obvious in the sPS/iPP (90/10 wt %) blend containing 5 wt % SP–A. Morphological analysis of the impact‐fractured surface of the ternary blends indicated that the sPS‐b‐aPP diblock copolymer contained in the SP–A alloy acted as an efficient compatibilizer by decreasing the dispersed‐phase iPP particle size, improving the interfacial adhesion, and generating a stable microphase‐separated state. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1596–1605, 2003
Understanding the viscoelastic properties of extruded polypropylene wood plastic composites
Authors: Son Jungil , Gardner Douglas J. , O'Neill Shane , Metaxas Costas 
Published: May 2003

AbstractThe main goal of this study was to analyze the effect of process additives, that is, maleated polypropylene (MAPP), and a nucleating agent on the viscoelastic properties of different types of extruded polypropylene (PP) wood plastic composites manufactured from either a PP homopolymer, a high crystallinity PP, or a PP impact copolymer using dynamic mechanical thermal analysis. The wood plastic composites were manufactured using 60% pine wood flour and 40% PP on a Davis‐Standard Woodtruder™. Dynamic mechanical thermal properties, polymer damping peaks (tan δ), storage modulus (E′), and loss modulus (E″) were measured using a dynamic mechanical thermal analyzer. To analyze the effect of the frequency on the dynamic mechanical properties of the various composites, DMA tests were performed over a temperature range of −20 to 100°C, at four different frequencies (1, 5, 10, and 25 Hz) and at a heating rate of 5°C/min. From these results, the activation energy of the various composites was measured using an Arrhenius relationship to investigate the effect of MAPP and the nucleating agent on the measurement of the interphase between the wood and plastic of the extruded PP wood plastic composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1638–1644, 2003
Synthesis and photoluminescent properties of poly(aryl ether)s containing alternate emitting and electron‐transporting moieties
Authors: Wang S. J. , Tjong S. C. , Meng Y. Z. , Fung M. K. , Lee S. T. , Hay Allan S. 
Published: May 2003

AbstractA new diphenylbutadiene‐containing bisphenol was successfully synthesized from benzylideneaniline and 4‐propenylanisole via an anil synthetic method. A series of copoly(arylene ether)s consisting of an alternate isolated blue chromophore (diphenylbutadiene) and an electron‐transporting moiety (1,3,4‐oxadiazole) was synthesized and characterized. High molecular weight copoly(arylene ether)s with an inherent viscosity of >0.5 dL/g were prepared by the nucleophilic displacement reaction of oxadiazole‐activated bis‐fluorocompounds with bisphenols. Introduction of ether linkages into the copolymers led to an enhanced solubility in organic solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone (NMP). The resulting copolymers can be cast into tough and transparent films. The copolymers were amorphous in structure with high glass transition temperatures ranging from 182.29 to 194.50°C. They also exhibited good thermal stability with the maximum decomposition temperatures higher than 500°C in nitrogen. The absorption peaks of these copolymers in thin films varied from 375 to 391 nm, while the photoluminescent peaks varied from 410 to 433 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1645–1651, 2003
Consequences of eliminating adenosine A1 receptors in mice
Authors: Fredholm Bertil B. , Halldner Linda , Johansson Catarina , Schulte Gunnar , Lövdahl Cecilia , Thorén Peter , Dunwiddie Thomas V. , Masino Susan A. , Poelchen Wolfgang , Diao Lihong , Illes Peter , Zahniser Nancy R. , Valen Guro , Tokuno Shinichi , Sommerschild Hilchen , Giménez‐Llort Lydia , Fernández‐Teruel Alberto , Escorihuela Rosa M. , Wiesenfeld‐Hallin Zsuzsanna , Xu Xiao‐Jun , Hårdemark Anna , Herlenius Eric , Pekny Milos , Gebré‐Medhin Samuel , Brown Russell , Ollerstam Anna , Persson A. Erik G. , Skøtt Ole , Johansson Björn 
Published: May 2003

AbstractThe second coding exon of the adenosine A1 receptor gene was eliminated by homologous recombination. The phenotype of mice (mixed C57B6/129OlaHsd background) was studied, using siblings from matings of heterozygous mice. Among the offspring the ratio between+/+,+/−and−/−animals was 1:2:1. Over the first half‐year—at least—growth and viability were the same in all genotypes. Binding of A1 ligands was eliminated in−/−mice and halved in+/−mice. Blood pressure was increased in−/−mice and this was paralleled by an increase in plasma renin. Heart rate was unaffected, as was contractility. Furthermore, the response of the perfused heart to ischemia was similar in+/+and −/−hearts. However, remote preconditioning was eliminated in−/−mouse hearts. Tubuloglomerular feedback in the kidney was also lost in−/−mice. The analgesic response to a non‐selective adenosing receptor agonist was lost in−/−mice, which also showed hyperalgesia in the tail‐flick test. There was a slight hypoactivity in−/−mice, but responses to caffeine were essentially normal. The inhibition of excitatory neurotransmission in hippocampus by adenosine was lost in−/−mice and reduced in+/−mice. Responses to ATP were affected similarly. Hypoxic depression of synaptic transmission was essentially eliminated in hippocampus and hypoxic decrease in spinal respiratory neuron firing was markedly reduced. These results show that adenosine A1 receptors play a physiologically important role in the kidney, spinal cord, and hippocampus and that they are critically important in the adaptive responses to hypoxia. Drug Dev. Res. 58:350–353, 2003. © 2003 Wiley‐Liss, Inc.
Modulation of voltage‐ and ligand‐gated ion channels by neuronal P2Y receptors
Authors: Wirkner Kerstin , Köles Laszlo , Fürst Susanna , Illes Peter 
Published: May 2003

AbstractThe present review summarizes data about the properties, distribution, and effects of neuronal P2Y receptors. Extracellular nucleotide receptors can be classified into two types belonging either to the P2X (ligand‐gated cationic channels) or the P2Y type (G protein‐coupled receptors). Neuronal P2Y receptors comprise five cloned and functionally defined classes of which P2Y1, P2Y6, P2Y11, P2Y12, and P2Y13 occur in the central nervous system. Various types of P2Y receptors stimulate inwardly rectifying potassium channels, positively or negatively modulate the high‐voltage activated Ca2+ current and increase the intracellular free Ca2+ concentration in neuronal preparations. Moreover, in a subpopulation of pyramidal cells of the rat prefrontal cortex (PFC), the P2Y2 receptor potentiates the function of a ligand‐gated cationic channel, the N‐methyl‐D‐aspartate (NMDA)‐type excitatory amino acid receptor. This effect is G protein‐mediated and utilizes the phospholipase C/inositol 1,4,5‐trisphosphate/Ca2+/calmodulin kinase II pathway. It appears that P2Y2 receptors situated at astrocytes release glutamate, which in turn modulates NMDA receptors of neighbouring neurons via stimulation of group I metabotropic glutamate receptors. In contrast, P2Y1 receptors inhibit the conductance of NMDA receptor‐channels in all PFC pyramidal cells investigated. This effect is fast in onset and does not depend on G protein activation. It is suggested that P2Y1 receptors alter the function of NMDA receptors by a direct protein–protein coupling in the membrane. Because ATP and dopamine are supposed to be coreleased from dopaminergic fibers onto layer V pyramidal cells, both neurotransmitters may interact with the neuronal NMDA receptor. Hence, D1 dopamine receptors and P2Y1/P2Y2 receptors may be involved in the fine tuning of higher order cognitive functions including learning and memory. Drug Dev. Res. 59:49–55, 2003. © 2003 Wiley‐Liss, Inc.
Inhibition of the nucleoside transporter inhibits disease progression in the rat adjuvant‐induced arthritis model
Authors: Kosaka Hidekazu , Koshiba Masahiro , Nakazawa Takashi , Tsuji Goh , Saegusa Jun , Kanagawa Sugayo , Saura Ryuichi , Kurosaka Masahiro , Yoshino Shin , Kumagai Shunichi 
Published: May 2003

AbstractWe investigated the in vivo effects of the nucleoside transporter inhibitor nitrobenzylmercaptopurine (NBMPR) on rat adjuvant‐induced arthritis. This agent inhibits uptake of adenosine into cells, presumably leading to increased levels of extracellular adenosine. Arthritis was induced in 7‐week‐old male Lewis rats by injection of incomplete Freund's adjuvant containing heat‐killed Mycobacterium butyricum into the base of the tail on day 0. The rats were then treated from day 0 with daily intraperitoneal injections of NBMPR (50 mg/kg/d in 1 ml of saline) or saline alone (untreated). The onset and progression of arthritis was evaluated daily using the arthritis severity index (0–4) for swelling and redness in four joints (bilateral front‐ and hind‐paws), with a score of 0 representing no rheumatoid changes and a score of 4 representing the most severe changes. Body weights were also measured to monitor the systemic antiarthritic effects of NBMPR as well as its systemic toxicity. On the last day (day 35), the rats were killed, and radiographic and histopathological assessments of their hind‐paws were conducted. The onset of arthritis was detected on the same day in both NBMPR‐treated and untreated arthritic rats, but subsequent disease progression was suppressed significantly in NBMPR‐treated rats. Radiographic (e.g., bone erosion and destruction) and histopathological (e.g., cell infiltration and cartilage erosion) findings confirmed the improved condition of the NBMPR‐treated rats. There was no significant difference in body weight among the rats. Thus, increasing extracellular adenosine with NBMPR appears to suppress the progression of arthritis. Drug Dev. Res. 58:479–485, 2003. © 2003 Wiley‐Liss, Inc.