bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of the Removal of Minor Amounts of H2S from Natural Gas by Activated Carbon
Authors: Zhou Li , Chen Ping , Li Ming , Zhou Yaping
Published: May 2003

Studies have been made of the removal of minor amounts of H2S from natural gas by activated carbon. The surface alkalinity of the carbon had a considerable effect on the H2S capacity, although this was not permanent. Thus, when the carbon surface became neutral, the H2S content remained constant after the initial cycles of the purification/regeneration operation. The presence of water in natural gas was found to be critical for the use of activated carbon as a means of sweetening natural gas. However, although it enhanced the H2S capacity of the carbon, it made regeneration of the latter very difficult.
Solid Acids from Persulphated and Perchlorated Physical Mixtures of Zirconium and Titanium Hydroxides
Authors: Shafei Gamal M.S. El , Philip Christine A.
Published: May 2003

Calcination at 650°C of a physical mixture of zirconium and titanium hydroxides led to the formation of the corresponding oxides, monoclinic zirconia and anatase. The adsorption of perchlorate or persulphate anions (as 0.05, 0.1, 0.2 or 0.4 M aqueous solutions) before calcination did not inhibit crystallization; however, perchlorate anions activated the formation of rutile in addition to the predominant anatase phase. Indeed, the adsorption of perchlorated anions prior to calcination allowed the thermodynamically less stable tetragonal phase of zirconia to be detected in addition to monoclinic zirconia at ambient temperature. In contrast, the adsorption of persulphate anions before calcination stabilized the tetragonal phase with no rutile phase being detected in this case.

Infrared spectroscopy showed that adsorbed S2O82– anions were held more strongly by the solid than ClO4− anions which tended to decompose when the solid was calcined. The acidities of the solid acids produced because of S2O82– or ClO4−anion adsorption were studied via the adsorption of pyridine (pKa = 5.3) from cyclohexane solution. The amounts and strengths of the acid sites formed during persulphate treatment were higher than those resulting from perchlorate adsorption. The strength of the acid sites formed on samples calcined before loading with S2O82– or ClO4− anions showed no significant differences. Variations detected in the structural aspects arising from S2O82– or ClO4− anion adsorption were reflected in the texture as assessed by nitrogen adsorption at −196°C.
Hydrogenolysis of n-Butane over Ru/Al2O3 Catalysts
Authors: Ryczkowski Janusz , Kuśmierz Marcin , Nazimek Dobiesław , Pasieczna Sylwia
Published: May 2003

Preliminary studies were undertaken of the preparation parameters of DIM (double impregnation method) influencing metal loading, ruthenium catalyst dispersion and n-butane hydrogenolysis. Ruthenium red was used as the metal precursor of Ru/Al2O3 catalysts. The infrared spectra of ruthenium red and EDTA adsorbed on alumina indicated that interaction occurs between adsorbates and the support surface. An extension of the impregnation time by ruthenium red caused a slight shift of the asymmetric –COO− band that may be explained by interaction between ruthenium and adsorbed EDTA. The small change in the –COO− band position was due to the nature of the metal–EDTA bond formed. An increase in metal loading led to an increase in ruthenium dispersion. Measurements of the rate of hydrogenolysis of n-butane were carried out in a gradientless reactor. All kinetic experiments were conducted under conditions where the hydrogen/n-butane molar ratio was 9:1, and involved isothermal determination of the relationship between the n-butane reaction rate and the corresponding degree of conversion (iso-X). The absence of propane and the presence of isobutane (at lower temperature) among the products were discussed.
Control of the Emission of Ammonia through Adsorption in a Fixed Bed of Activated Carbon
Authors: Rodrigues C.C. , Moraes D.
Published: May 2003

The increase in atmospheric pollution caused by polluting gases has made it necessary to conduct studies aimed at decreasing or treating the emissions of such gases. Due to its increasing presence in the atmosphere, ammonia is one of the most pre-eminent of these. The present work studied the control of the emission of this gas through its adsorption in a fixed bed of activated carbon. The results showed that the adsorption capacity increased from approximately 0.2 to 1.9 mg NH3/g carbon as the concentration of ammonia in the gaseous mixture increased (600, 1200, 1800 and 2400 ppm) at the three temperatures employed (40, 80 and 120°C). Increasing the temperature at the concentrations studied caused a decrease in the adsorption capacity, which was affected to a more significant extent by temperature than by the ammonia concentration in the gaseous mixture.
Adsorption of Fuchsin Basic on Copper in Citric Acid
Authors: Polo J.L. , Cano E. , Pinilla P. , Bastidas J.M.
Published: May 2003

The adsorption of Fuchsin Basic (FB) on copper surfaces in citric acid solutions whose concentrations ranged from 0.001 to 0.1 M was investigated using gravimetric measurements. The concentrations of FB studied ranged from 1 × 10−5 to 1 × 10−1 M with adsorption experiments being conducted at temperatures from 298 K to 328 K. The adsorption mechanism is discussed in terms of the applicability of the conventional Frumkin, Bockris–Swinkels and Kastening–Holleck isotherms, amongst others. The best fit was obtained using the Frumkin isotherm model. A thermodynamic/kinetic model of adsorption was also fitted.
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.
Computation of Engine Noise Propagation and Scattering off An Aircraft
Authors: Stanescu D. , Xu J. , Hussaini M.Y. , Farassat F.
Published: May 2003

The purpose of this paper is to demonstrate the feasibility of computing the fan inlet noise field around a real twin-engine aircraft, which includes the radiation of the main spinning modes from the engine as well as the reflection and scattering by the fuselage and the wing. This first-cut large-scale computation is based on time domain and frequency domain approaches that employ spectral element methods for spatial discretization. The numerical algorithms are designed to exploit high-performance computers such as the IBM SP4. Although the simulations could not match the exact conditions of the only available experimental data set, they are able to predict the trends of the measured noise field fairly well.
The development of subjective group dynamics: When in‐group bias gets specific
Authors: Abrams Dominic , Rutland Adam , Cameron Lindsey , Marques Josém.
Published: May 2003

Children aged 6–7 years and 10–11 years evaluated an in‐group or out‐group summer school and judged in‐group or out‐group members whose attitudes towards the summer schools were either normative or anti‐normative. According to a subjective group dynamics model of intergroup processes, intergroup differentiation and intragroup differentiation co‐occur to bolster the validity of in‐group norms. The hypothesis that this process develops later than simple in‐group bias was confirmed. All children expressed global in‐group bias, but differential reactions to in‐group and outgroup deviants were stronger among older children. Moreover, the increasing relationship, with age, between in‐group bias and evaluative preferences for in‐group and out‐group members that provide relative support to in‐group norms, is mediated by the degree of perceptual differentiation among group members.
Effects of in‐group and out‐group ethnicity on children's attitudes towards members of the in‐group and out‐group
Authors: Nesdale Drew , Maass Anne , Griffiths Judith , Durkin Kevin
Published: May 2003

This study tested predictions drawn from social identity development theory (SIDT) (Nesdale, 1999a) concerning the development of young children's ethnic attitudes. 5‐7‐ and 9‐year‐old children (N = 159) participated in a minimal group study in which they were assigned to a team which had higher drawing ability than a competitor team. The team members were revealed to be of the same (Anglo‐Australian) vs. different (Pacific Islander) ethnicity (in‐group ethnicity). The ethnicity of the competitor team was varied in the same way. The children subsequently rated their liking for, and similarity to, the in‐group and the out‐group, and the extent to which they wished to change groups. Children liked in‐group members more than out‐group members. Liking for in‐group members was unaffected by the ethnic composition of the groups, but liking for outgroup members was reduced when the ethnic composition of the out‐group differed from that of the in‐group. Children felt most similar to same‐group, same‐ethnicity members and least similar to different ethnicity out‐group members. The desire to change teams increased with age but there was no intention to align with same ethnicity individuals. The extent to which the findings provide support for SIDT is discussed.
The development of national in‐group bias: English children's attributions of characteristics to English, American and German people
Authors: Barrett Martyn , Wilson Hannah , Lyons Evanthia
Published: May 2003

This study investigated the development of national in‐group bias in 5–11‐year‐old children. Three hundred and seven English children were asked to attribute characteristics to their own national group either on its own or in conjunction with attributing characteristics to one of two national out‐groups, either Americans or Germans. The importance which the children ascribed to their own national identity in relationship to their other social identities was also assessed. It was found that, with increasing age, there was an increase in the number of negative characteristics attributed to the national in‐group, and an increase in the number of positive characteristics attributed to the two out‐groups, the net result being an overall reduction in in‐group bias across this age range. However, in‐group favouritism was still exhibited at all ages. Greater importance was attributed to national identity with increasing age. However, the characteristics attributed to the English in‐group did not vary as a function of the comparative out‐group which was present while the attributions were being made. The presence of a comparative out‐group also did not affect the importance that was ascribed to the national identity. These findings suggest that children are relatively insensitive to the prevailing comparative context when making judgments about national groups.
Adolescents' approval of peer and spousal retribution in their culture vs. other cultures: The role of group stereotypes
Authors: Pitner Ronald O. , Astor Ron Avi , Benbenishty Rami , Haj‐Yahia Muhammad M. , Zeira Anat
Published: May 2003

This study examined whether negative group stereotypes similarly affect adolescents' reasoning about peer and spousal retribution in interpersonal situations. Findings from cognitive domain theory, school violence, family violence, and group stereotyping and prejudice literatures were used to examine this. The sample of adolescents was drawn from northern and central Israel and consisted of 1,168 Arab and Jewish students (grades 7–11). A quasi‐experimental between‐subject design was used, in which the students in each grade were randomly assigned to one of two peer retribution scenarios and one of two spousal retribution scenarios. In each scenario, only the ethnicity of the peers and married couples depicted in the story was systematically altered. The study was a 2 (Arab/Jewish respondent) 2 (peer retribution scenarios) 2 (spousal retribution scenarios) factorial design. The findings provide evidence that Arab and Jewish students have negative stereotypes about one another; however, these group stereotypes did not affect their judgments and justifications about peer and spousal retribution. Jewish and Arab students judged peer retribution similarly, but differed in their judgments of spousal retribution. However, altering the ethnic background of the individuals in the scenarios did not affect respondents' judgments. This suggests that respondents in both groups did not base their judgments on negative stereotypes about the out‐group, but instead were focusing on the behavioural act itself. Overall, the vast majority of respondents condemned retribution based on moral, social conventional and personal reasons. This inquiry provides evidence that it was the number of justifications endorsed within a specific domain that distinguished Arab and Jewish respondents. Theoretical and practical implications are discussed.
A longitudinal, naturalistic and cross‐cultural study on emotions in early infant‐parent imitative interactions
Authors: Kokkinaki Theano
Published: May 2003

The present longitudinal, naturalistic and cross‐cultural study aims to investigate and extend our understanding of the intersubjective nature of the early imitations that may be observed in free interactions between young infants and their parents. Thirty infants, 15 from Greece and 15 from Scotland, were observed separately with their mothers and fathers at home every 2 weeks, from the second to the sixth month after birth. In each dyad, the emotional states of both interacting partners before, during and after the imitative episodes were subjected to microanalysis. The results indicate that emotional coordination, either by direct matching of expressions or by attunement, precedes, accompanies and follows imitation. This kind of coordination was found to be the same in Crete and Scotland, and for parents and infants of both sexes. It is concluded that this coordination of emotions with early imitative phenomena is evidence of motivational coherence, both within the subjects, and between them in an intersubjective play.
Pre‐school children's understanding of the emotional consequences for failures to act prosocially
Authors: Sy Susan R. , Demeis Debra K. , Scheinfield Rachel E.
Published: May 2003

This study compares 4‐ and 5‐year‐old children's assessment of the emotional consequences of failures to act prosocially with their assessment of the emotional consequences for prosocial and victimization situations. After listening to stories illustrating each of the socio‐moral situations, children rated the emotional consequences for an actor, recipient and observing teacher and justified their ratings. Findings show that pre‐school children's emotion ratings for failures to act prosocially differed from their emotion ratings for prosocial and victimization behaviours. Preschool children's ratings of an actor's emotions depended on the presence or absence of an observing teacher in prosocial and victimization situations, but not in failures to act prosocially. This study illustrates the complexity of young children's reasoning about failures to act prosocially and highlights the importance of contextual influences on children's understanding of socio‐moral emotions.
Time budgets of the mothers of pre‐school children: An analysis of mother‐child joint activities
Authors: Galboda‐Liyanage Kumari Chandani , Scott Stephen , Prince Martin James
Published: May 2003

The objective of this research was to describe how a group of mothers of pre‐school children spend their days in relation to the index pre‐school child and in general. We examined time use by means of the Yesterday's interview for Mothers of Pre‐schoolers (YIMP), a semi‐structured interview, with 31 mothers recruited from mother and toddler groups. Detailed time budgets were obtained on three full days covering the content, duration and environmental context of mother‐child joint activities. Reading was the most common joint activity. A substantial proportion of activities took place outside the home. Research implications in relation to the environmental context of joint activities are discussed.
The development of representations as children learn about balancing
Authors: Pine Karen , Messer David
Published: May 2003

The proposal that there is a simple dichotomy between implicit and explicit knowledge fails to fully explain why children and adults can perform a task with increasing awareness and efficiency before they are able to completely understand and explain their success. Karmiloff‐Smith (1992) in her Representational Redescription (RR) model claims that representations of implicit procedures can be redescribed into further levels, E1, E2 and E3, which gradually afford increasing conscious and linguistic access. This study examines how 25 children's representations about balancing a beam on a fulcrum changed over time, as they attempted a set of tasks each day for five consecutive days. Children's behaviour was classified into seven levels, rather than the four identified by Karmiloff‐Smith, and the path through these levels is traced as children progressed over the 5‐day period. This provided one form of validation about the developmental sequence of the levels. Additional tasks assessed the flexibility of the children's representations, operationalized either as an ability to predict which beams would balance, or to identify which picture showed a beam that would balance on a fulcrum. The findings from these assessments shed light on the conscious accessibility and transportability of the children's knowledge, independent of their overt behaviour. The data also reveal a complexity in cognitive functioning which could not be identified from observations of performance alone. This research thus provides a theoretical endorsement and extension of Karmiloff‐Smith's multi‐representational framework of cognitive development and empirical support for a hypothesized path of development through the representational levels.
Long‐term memory effects on verbal short‐term memory: A replication study
Authors: Majerus Steve , Van der Linden Martial
Published: May 2003

The influence of lexico‐semantic language representations stored in long‐term memory (LTM) on short‐term memory (STM) performance has been studied extensively in adults. However, there are relatively few data on lexico‐semantic LTM effects on STM in children. On the other hand, the influence of phonological LTM effects on STM has been studied more extensively in children than in adults. In this study, we explored whether these different LTM effects on verbal STM could be replicated in both adults and children by administering immediate serial recall tasks (ISR) for high‐ and lowfrequency words, for high‐ and low‐imageability words, for words and non‐words, and for high and low phonotactic frequency non‐words to 6‐, 8‐, and 10‐year‐old children, to adolescents and to adults. Significant word frequency, lexicality and phonotactic frequency effects were observed in all age groups, as well as a word imageability effect which was, however, weaker than the other three effects. Our data suggest that LTM effects on STM are equivalent in both children and adults.
Mechanical performance of blends of thermotropic liquid crystalline polymer spheres‐dispersed polycarbonate
Authors: Xue Yongfu , Zhang Jun , Zheng Xuejing , He Jiasong
Published: May 2003

Liquid 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

The 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

Ag‐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

Radical 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

In 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

A 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

Small‐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

For 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

A 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

The 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

A 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

The 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

The 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

We 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.
Adenine analogs as potential differentiation therapy agents for acute myeloid leukemia
Authors: Honma Yoshio
Published: May 2003

Although the frequency of complete remission in acute myeloid leukemia (AML) has increased, the median duration of such remission is only 9–15 months, even when remission is achieved by treatment with conventional cytotoxic antileukemic drugs. These results clearly call for improved therapies. AML is characterized by a differentiation block leading to the accumulation of immature cells. This maturation arrest can be reversed by certain agents. Several adenine analogs effectively induce the morphologic and functional differentiation of leukemia cells. Thus, adenine analogs, alone or in combination with other differentiation‐inducing agents, may be effective for the therapy of AML. However, the antileukemic analog that is the most suitable for the treatment of AML may depend on the leukemia subtype, since the sensitivity of leukemia cells to these analogs varied greatly among leukemia subtypes. The clinical usefulness of these adenine analogs is discussed. Drug Dev. Res. 59:14–22, 2003. © 2003 Wiley‐Liss, Inc.
Adenosine receptors and human melanoma
Authors: Merighi Stefania , Baraldi Pier Giovanni , Gessi Stefania , Iannotta Valeria , Klotz Karl‐Norbert , Leung Edward , Mirandola Prisco , Tabrizi Mojgan Aghazadeh , Varani Katia , Borea Pier Andrea
Published: May 2003

Increased concentrations of extracellular adenosine are reached in ischemic or inflamed tissues but have also been detected inside tumoral masses. This latter finding may account for an important role of adenosine in the pathogenesis of tumors and its contradictory effects on cell survival and proliferation remain to be reconciled with the presence of specific adenosine receptor subtypes. This article reviews the pharmacological and biochemical characterization of adenosine receptors in the human malignant melanoma A375 cell line and the functional significance of their presence in a tumor cell type. We show that adenosine improves cell proliferation via A2A receptors while it arrests the cells at G1/G0 cell cycle phase through A3 stimulation. Furthermore, adenosine triggers a survival signal via A3 receptor stimulation while it simultaneously promotes cell death via A2A receptor activation, inducing a signaling pathway that involves protein kinase C (PKC) and mitogen‐activated protein kinases (MAPKs). Drug Dev. Res. 58:377–385, 2003. © 2003 Wiley‐Liss, Inc.
Extracellular ATP, P2 receptors, and inflammation
Authors: Virgilio Francesco Di , Ferrari Davide , Idzko Marco , Panther Elisabeth , Norgauer Johannes , Sala Andrea la , Girolomoni Giampiero
Published: May 2003

Over the past few years, P2 receptors have emerged as new potential players in the early phases of inflammation in their function of chemotactic receptors, triggers of proinflammatory cytokine release, and cytotoxic molecules. However, more recent data suggest that the role of P2 receptors in immunity is much more widespread and touches the very heart of the initiation of the immune response, i.e., antigen presentation by dendritic cells. Drug Dev. Res. 59:171–174, 2003. © 2003 Wiley‐Liss, Inc.
Critical ATP parameters associated with blood and mammalian cells: Relevant measurement techniques
Authors: Abraham Edward H. , Salikhova Anna Y. , Hug Eugen B.
Published: May 2003

We have developed an integrated package that includes software programs and algorithms for measuring in vivo total blood ATP, extracellular blood ATP, blood ATP release rates, and plasma ATP breakdown rates. This clinically tested methodology improves upon existing luciferin/luciferase and high‐performance liquid chromatography assay techniques in that it involves the multidetector luminometric system for determination of blood ATP parameters with simultaneous monitoring of ATP standards and standard curve generations with r2 > 0.99 and increased speed of preparation and assay time (time necessarily for 96‐well plate preparation, assay itself, and analysis). The system and associated software program permits analysis blood ATP parameters in mol, mol/L, or mol/red blood cell (RBC) and has been extensively tested with samples measured in clinics and with samples obtained and measured at the patient bedside. The mobility of the system and ability to perform measurements on location is an important consideration and feature because of the fact that ATP blood levels are rapidly hydrolyzed and hence extremely sensitive to any perturbations associated with any vigorous manipulations during the processing and analysis. EDTA inhibition of extracellular ATP hydrolysis permits determination of extracellular ATP (plasma) and ATP release rates levels performed by iterative measurements performed on sequentially diluted blood aliquots. Back‐extrapolation permits close approximation of the in vivo blood ATP parameters. The assay system is capable of detecting RBC ATP release rates as low as 10,000 ATP molecules·RBC−1min−1. Drug Dev. Res. 59:152–160, 2003. © 2003 Wiley‐Liss, Inc.
Robert Berne: His place in the history of purine research
Authors: Olsson Ray A.
Published: May 2003

Last year the purine community lost one of its leaders, Prof. Robert Berne of the University of Virginia. There is little that I can add to the eulogies that appeared at the time of his passing. Rather, I thought I would use this article to place his work in the perspective of over 200 years of research on purines that led up to and then resulted from his work. The story involves scientific notables, many of them Nobel laureates (indicated with an asterisk). Drug Dev. Res. 58:296–301, 2003. © 2003 Wiley‐Liss, Inc.