bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing children's responsibility to take action against bullying: Evaluation of a befriending intervention in Italian middle schools
Authors: Menesini Ersilia , Codecasa Elena , Benelli Beatrice , Cowie Helen
Published: March 2003

This paper reports on the evaluation of a peer support model implemented in two Italian secondary middle schools as an anti‐bullying intervention. Specifically, the aims of the intervention were (1) to reduce bullying episodes through developing in bullies an awareness of their own and others' behaviour, (2) to enhance children's capacity to offer support to the victims of bullying, (3) to enhance responsibility and involvement on the part of bystanders, (4) to improve the quality of interpersonal relationships in the class group, and (5) to analyse possible age and gender differences related to the effect of intervention.

Two middle schools from central Italy took part in the study (age range of pupils, 11–14 years). In the two schools, nine classes (94 boys and 84 girls ) were part of the experimental group, whereas the remaining five classes formed the control group (63 boys and 52 girls). The intervention was implemented for one school year, from October 1998 to May 1999. Before and after the intervention, two measures were administered in the experimental and control classes: (1) a questionnaire on the participants' roles in bully/victim relationships, originally developed by Salmivalli et al. [1996: Aggressive Behavior 22:1–15] and revised for younger children by Sutton and Smith [1999: Aggressive Behavior 25:97–111], and (2) a questionnaire on attitudes toward bullying—an Italian questionnaire comprising 11 attitude items previously developed [Menesini E, et al. 1997: EARLI Conference] on the basis of Rigby and Slee's [1991: Journal of Social Psychology 131:615–627] pro‐victim scale. Given the within‐subjects design of the study, a MANOVA was run using time as the within‐subjects factor and sex and age as between‐subject factors.

The results of this short‐term study highlight the fact that a befriending intervention had a positive effect on the experimental classes, preventing the increase of negative behaviours and attitudes reported in the group that did not receive the intervention. The findings that related to the pro‐bullying roles and to the role of outsiders are particularly relevant since these roles remained stable or decreased in the experimental group, whereas they clearly increased in the control group. The opposite trend was registered for children's pro‐victim attitude, which shows a decrease in the control sample and good stability in the experimental group. On the whole, the intervention seemed to prevent the escalation of negative behaviours and attitudes that often develop spontaneously in young people of this age. Aggr. Behav. 29:1–14, 2003. © 2003 Wiley‐Liss, Inc.
Accelerated learning in colleges and universities
Authors: Wlodkowski Raymond J.
Published: March 2003

This chapter provides a research‐based overview of accelerated learning as a program and educational format in higher education today.
From the adult student's perspective: Accelerated degree programs
Authors: Kasworm Carol E.
Published: March 2003

Key research has identified adult students' beliefs about the importance of structure, relationships, student identity, and related beliefs about learning, as well as suggesting a conceptual model.
Accelerated and traditional formats: Using learning as a criterion for quality
Authors: Swenson Craig
Published: March 2003

Student learning is the major test of a program's quality, regardless of whether it is delivered in a traditional or accelerated format. Administrators and teachers in accelerated programs will increase effectiveness and build credibility by making sure that their programs employ best practices, measure results, and use assessment data for program improvement.
Accelerated learning: Future roles and influences
Authors: Wlodkowski Raymond J. , Kasworm Carol E.
Published: March 2003

This chapter explores the future of accelerated learning as an innovative force within higher education.
Laser Pruning of Carbon Nanotubes as a Route to Static and Movable Structures
Authors: Lim K.Y. , Sow C.H. , Lin J. , Cheong F.C. , Shen Z.X. , Thong J.T.L. , Chin K.C. , Wee A.T.S.
Published: March 2003

A simple focused laser beam pruning method is used to fabricate unique two‐ and three‐ dimensional structures (see Figure and the cover), without a pre‐patterned substrate and under ambient conditions. The construction of microscopic movable carbon nanotube (CNT) structures that are controlled by laser light are also reported. The technique allows a wide range of 3D CNT microstructures to be created.
Field‐Effect Transistors Based on Oligothienylenevinylenes: From Solution π‐Dimers to High‐Mobility Organic Semiconductors
Authors: Videlot C. , Ackermann J. , Blanchard P. , Raimundo J.‐M. , Frère P. , Allain M. , de Bettignies R. , Levillain E. , Roncali J.
Published: March 2003

The substitution pattern of oligothienylenevinylenes (see Figure) exerts a determining effect on the packing arrangement of individual oligomers in the solid state, and thus on field‐effect mobility. These two parameters are tightly correlated to the propensity of the corresponding cation radical to dimerize in solution. The analysis of the π‐dimerization of conjugated cation radicals in solution could be used to screen new candidates for devices.
An Improved Synthesis of High‐Aspect‐Ratio Gold Nanorods
Authors: Busbee B.D. , Obare S.O. , Murphy C.J.
Published: March 2003

By using seed‐mediation and careful control of pH, gold nanorods of high aspect ratio (∼ 18–25, 20 in the Figure) have been produced by surfactant‐directed synthesis. The yield is high (∼ 90 %) and the method can be readily adapted for scaling up.
Striped Metal Nanowires as Building Blocks and Optical Tags
Authors: Keating C.D. , Natan M.J.
Published: March 2003

Sequential electrodeposition within a porous template can be used to prepare striped nanowires with tailorable dimensions and composition. Variations in composition along the length of the wire can be used to incorporate electrical functionality, optical contrast, and/or desired surface chemistry. Nanowires can be functionalized with chemical or biochemical reagents appropriate for assembly or biosensing. Therefore, these particles are interesting as building blocks for nanoscale electronics and as “barcodes” for both biological and non‐biological tagging applications. In this article, we briefly discuss the synthesis and optical readout of striped metal nanowires, as well as progress towards each of these potential applications.
Mechanisms for the Shape‐Control and Shape‐Evolution of Colloidal Semiconductor Nanocrystals
Authors: Peng X.
Published: March 2003

The shape of CdSe and other semiconductor nanocrystals is controlled, producing dots, rods, rice‐shaped particles, tetrapods, or other elongated shapes. Monomer concentration in the growth solution is the determining factor in shape‐control and shape‐evolution. The elongated shapes could be transformed into more spherical shapes if the monomer concentration in the solution was lowered to a certain level, and spherically shaped nanocrystals could grow to elongated shapes by simply increasing the monomer concentration. The precursors are stable, inexpensive, and relatively non‐toxic, and therefore good choices for the growth of nearly monodisperse and shape‐controlled nanocrystals.
Clinical presentation of severe anemia in pediatric patients with sickle cell anemia seen in Enugu, Nigeria
Authors: Juwah A.I. , Nlemadim A. , Kaine W.
Published: March 2003

Anemia is a major cause of morbidity and mortality among patients with sickle cell anemia. In this study, 108 episodes of severe anemia were prospectively evaluated in 108 patients with hemoglobin SS disease attending the pediatric sickle cell clinic of the University of Nigeria Teaching Hospital, Enugu, Nigeria. Young children between the ages of 2 and 4 years were found to be at the greatest risk of developing anemic crises (severe anemia). There was a gradual but progressive decline in the incidence of severe anemia in the age range 8–16 years old. Upper respiratory tract infections are the most commonly associated infections in patients with severe anemia. Others included malaria, septicemia, urinary tract infection, acute chest syndrome, and osteomyelitis. Their role in precipitating episodes of severe anemia among the patients studied could not be fully evaluated. Pallor, jaundice, and fever were the most commonly encountered symptoms in patients with severe anemia on admission. About half of the parents/guardians failed to notice severe anemia among the patients studied, perhaps due to the dark color of the African skin. Caregivers need to be educated on how to recognize anemia among patients with sickle cell anemia when they develop febrile episodes. Am. J. Hematol. 72:185–191, 2003. © 2003 Wiley‐Liss, Inc.
Comparative survival advantage of males with down syndrome
Authors: Glasson E.J. , Sullivan S.G. , Hussain R. , Petterson B.A. , Montgomery P.D. , Bittles A.H.
Published: March 2003

In virtually all countries life expectancy is longer in females than in males. A multigeneration, population‐based dataset was used to investigate whether a gender‐specific difference in life expectancy could be determined in a large cohort (n = 1,332) of people with Down syndrome resident in Western Australia. Contrary to the established pattern of longevity in the general population, and in most people with intellectual disability, males with Down syndrome had a significantly greater life expectancy than females with the same disorder. The reasons for this atypical finding are discussed in terms of the patterns of morbidity experienced by people with Down syndrome, especially at early and late stages of their lifespan. Am. J. Hum. Biol. 15:192–195, 2003. © 2003 Wiley‐Liss, Inc.
Center of body mass and the evolution of female body shape
Authors: Pawłowski Bogusław , Grabarczyk Marzena
Published: March 2003

Among primates, the genus Homo has a unique sexual dimorphism in general body shape. The stenotypic female “hourglass figure” has often been attributed to sexual selection. Sexual dimorphism both in shape and in position of the center of body mass (CoM) emerges during puberty and is related to hormonal influences. These are only the proximal and not the ultimate causes of this feature. This article explores the hypothesis that the evolutionary (i.e., ultimate) reason for female body shape and male preference for a lower waist‐to‐hip ratio (WHR) is due to the acquisition of bipedal locomotion and different biomechanical constraints on each sex. The demands of pregnancy and subsequently carrying infants may have more tightly constrained CoM in females than in males. A lower‐position of CoM relative to height (RCoM=(CoM/height)*100%) would contribute to better stability during pregnancy and infant carrying. Using body measurements from 119 female students, we show that RCoM correlates negatively with only maximal thigh circumference and positively with only WHR and shoulder width. The relationship between RCoM and traits that best characterize female body shape seems to confirm a hypothesis of biomechanical selection pressure that may have acted on Homo female morphology, thus contributing to sexual dimorphism. Am. J. Hum. Biol. 15:144–150, 2003. © 2003 Wiley‐Liss, Inc.
Coliforms in the water and hemoglobin concentration are predictors of gastrointestinal morbidity of Bangladeshi children ages 1–10 years
Authors: Bhargava Alok , Bouis Howarth E. , Hallman Kelly , Hoque Bilqis A.
Published: March 2003

The presence of pathogens in the water and children's poor nutritional status are likely to increase morbidity in developing countries. Understanding the interactions between the environmental and nutritional factors is important from the standpoint of improving child health. In this study, we analyzed the effects of fecal and total coliforms in the water available at the source and that stored in the household on the spells of gastrointestinal morbidity of 99 Bangladeshi children at three time points in an 8‐month period. Fecal and total coliforms in the stored water were significant predictors (P< 0.05) of morbidity that was modeled using dynamic random effects models. Moreover, children with better hemoglobin status experienced lower morbidity. An empirical model for the proximate determinants of hemoglobin concentration showed significant negative associations between children's hookworm loads and hemoglobin. While the children's intakes of bioavailable iron, iron from meat, fish, and poultry, and iron from animal sources were not significant predictors of hemoglobin status in this population, the need for broader interventions for improving child health was apparent. Am. J. Hum. Biol. 15:209–219, 2003. © 2003 Wiley‐Liss, Inc.
Satoyoshi syndrome in a caucasian girl improved with glucocorticoids—A clinical report
Authors: Cecchin Cláudia Rafaela , Félix Têmis Maria , Magalhães Richard B. , Furlanetto Tânia Weber
Published: March 2003

Satoyoshi syndrome (OMIM 600705) is a rare disorder of unknown cause characterized by progressive painful intermittent muscle spasms, amenorrhea, alopecia, malabsorption, and skeletal abnormalities mimicking a skeletal dysplasia. In this report, we describe a Caucasian 12‐year‐old girl that presented with characteristic manifestations, including alopecia, muscle cramps, and short stature with onset at age 7. Prednisone 60 mg/m2 every other day and amytriptiline 25 mg QD were administered. After 2 months, alopecia had significantly improved and muscle cramps had almost disappeared, so that glucocorticoid treatment was tapered. Follow‐up, 9 months later, showed a normal looking and asymptomatic girl. © 2003 Wiley‐Liss, Inc.
Allelic variants interaction of dopamine receptor D4 polymorphism correlate with personality traits in young Korean female population
Authors: Lee Heon‐Jeong , Lee Hong‐Seock , Kim Yong‐Ku , Kim Seung‐Hyun , Kim Leen , Lee Min Soo , Joe Sook‐Haeng , Jung In‐Kwa , Suh Kwang‐Yoon , Kim Sangduk
Published: March 2003

Polymorphism in exon III of the dopamine D4 receptor (DRD4) gene has been implicated to be associated with the human personality trait of novelty seeking (NS). For this study, we have investigated the possible association between 48‐bp VNTR in exon III and −521 C/T SNP of the DRD4 and personality traits among young (≈14 years of age) Korean female population. We found that the interaction between the two alleles of DRD4 polymorphism, 48‐bp VNTR and −521 C/T, were significantly high on NS (F = 4.88, P = 0.029) and persistence (P) (F = 5.05, P = 0.027) personality scores, suggesting that the variants of DRD4 gene influence the NS and P (persistent) personality traits. When analyzed independently, however, the two different alleles of DRD4 polymorphisms, 48‐bp VNTR and −521 C/T, there was no direct correlation with the personality traits. © 2002 Wiley‐Liss, Inc.
A “line item” approach to the identification of genes involved in polygenic behavioral disorders: The Adrenergic α2A(ADRA2A) gene
Authors: Comings D.E. , Gonzalez N.S. , Li S‐C Cheng , MacMurray J.
Published: March 2003

The usual approach for using single base pair polymorphisms (SNPs) for the investigation of the genetics of behavioral disorders is to examine a single diagnostic syndrome or personality trait based on variables relating to a cluster of behavioral symptoms. However, since some of these variables may address behaviors that are associated with one allele while others are associated with the other allele, the overall association may be non‐significant and significant sub‐syndromal associations may be missed. Thus, we have reversed the process in a technique we term a “line item” approach. As a test of the technique we have examined the association between genotypes of a C‐ > G‐1291 Msp I promotor SNP of the ADRA2A gene and 390 individual symptoms from a structured review of DSM‐IV criteria for twelve different groups of symptoms. We examined 334 individuals consisting of controls and subjects with Tourette syndrome (TS). Based on the mean scores for each genotype, those symptoms that were individually significant at α ≤ 0.05 fell into three major groups by mode of inheritance: allele 1 codominant (11 > 12 > 22), allele 2 codominant (22 > 12 > 11), and negative heterosis (12 < 11, 22). Within each mode of inheritance group, the number of symptoms that were significant for the twelve symptom clusters was compared by chi‐square analysis. This showed that symptoms were drawn from the diagnostic groups in a significantly non‐random fashion. Thus, the allele 1 codominant symptoms came from the anxiety, affective, schizoid, and somatization diagnostic groups (internalizing symptoms) (χ2 = 80.0, d.f. = 11, P ≤ 0.0000001), while the allele 2 codominant symptoms came from the ADHD and oppositional defiant/conduct disorder diagnostic groups (externalizing symptoms) (χ2 = 81.0, d.f. = 11, P ≤ 0.0000001). The questions that fell in the negative heterosis type of inheritance were not significantly associated with specific diagnostic groups (P = 0.87). These results showed that the ADRA2A gene was associated with symptoms of autonomic, sympathetic dysfunction from different diagnostic groups. The advantages of the “line item” approach include (a) the identification of the symptoms associated with each allele, (b) the identification of symptom clusters independent of DSM diagnoses, (c) the elucidation of heterosis and other mode of inheritance effects, (d) the distinction between an association with a primary disorder versus a comorbid disorder, (e) the identification of associations with sub‐syndromal symptom clusters that do meet full DSM‐IV criteria, and (f) the identification of symptom clusters across databases. © 2003 Wiley‐Liss, Inc.
Quantitative analysis of Neanderthal temporal bone morphology using three‐dimensional geometric morphometrics
Authors: Harvati Katerina
Published: March 2003

The temporal bone is the location of several traits thought to differentiate Neanderthals from modern humans, including some proposed Neanderthal‐derived traits. Most of these, however, are difficult to measure and are usually described qualitatively. This study applied the techniques of geometric morphometrics to the complex morphology of the temporal bone, in order to quantify the differences observed between Neanderthal and modern human anatomy. Two hundred and seventy modern human crania were measured, representing 9 populations of 30 individuals each, and spanning the extremes of the modern human geographical range. Twelve Neanderthal specimens, as well as Reilingen, Kabwe, Skhul 5, Qafzeh 9, and 4 Late Paleolithic European specimens, were included in the fossil sample. The data were collected in the form of three‐dimensional (3‐D) landmark coordinates, and specimen configurations were superimposed using generalized Procrustes analysis. The fitted coordinates were then analyzed by an array of multivariate statistical methods, including principal components analysis, canonical variates analysis, and Mahalanobis D2. The temporal bone landmark analysis was very successful in separating Neanderthals from modern humans. Neanderthals were separated from modern humans in both the principal components and canonical variates analyses. They were much further in Mahalanobis distances from all modern human populations than any two modern human groups were from each other. Most of the previously described temporal bone traits contributed to this separation. Am J Phys Anthropol 120:323–338, 2003. © 2003 Wiley‐Liss, Inc.
Direct Liquid‐Phase Sulfonation of Methane to Methanesulfonic Acid by SO3 in the Presence of a Metal Peroxide
Authors: Mukhopadhyay Sudip , Bell Alexis T.
Published: March 2003

Aktivierung von Methan durch Metallperoxide: Calciumperoxid dient als effektiver Radikalstarter bei der Flüssigphasensulfonierung von Methan zu Methansulfonsäure (MSA) durch SO3 [Gl. (1)]. Unter den günstigsten Reaktionsbedingungen wurde ein 91‐proz. Umsatz von SO3 zu MSA erzielt.
Kupfer‐Carben‐Komplexe: hochentwickelte Katalysatoren, neue Erkenntnisse
Authors: Kirmse Wolfgang
Published: March 2003

Die Steuerung der Selektivität reaktiver Zwischenstufen ist ein wichtiges Ziel in der organischen Chemie. Photochemisch oder thermisch aus Diazoverbindungen erzeugte Carbene lassen sich nicht von außen beeinflussen und bilden Produktgemische. Dagegen führt die katalytische Zersetzung von Diazoverbindungen zu selektiven Carbenoiden, die häufig in der Synthese verwendet werden – bei geringer Kenntnis ihrer Eigenschaften. Andererseits sind zahlreiche Carben‐Metall‐Komplexe bekannt, denen die carbenoide Reaktivität fehlt. Das Zusammenwirken von Experiment und Theorie liefert Informationen über die labilen Zwischenstufen der katalytischen Zersetzung von Diazoverbindungen. Im Mittelpunkt dieses Kurzaufsatzes stehen Kupfer‐Komplexe, doch werden auch andere Metalle berücksichtigt.
Effect of curing time and sulfur content on the dielectric relaxation of styrene butadiene rubber
Authors: Abd‐El‐Messieh S. L. , Abd‐El‐Nour K. N.
Published: March 2003

Dielectric investigations were carried out on styrene–butadiene rubber cured by an increase in either the sulfur content or curing time in a wide range of frequencies from 100 Hz up to 10 MHz and at room temperature (≈25°C). After subtraction, the losses due to the Maxwell–Wagner effect, the dielectric data showed deviation from the Debye formula but were found to be fitted in the frequency domain by the Havriliak–Nagami function, which is a combination of Cole–Cole and Cole–Davidson functions. This function describes the relaxation mechanisms of the aggregates caused by the movement of the main chain that were expected to be formed by the addition of the different ingredients to the investigated rubber. These mechanisms are also discussed in terms of the distribution function of Fröhlich between two limiting values of relaxation times τ1 and τ2. The relaxation times obtained from both functions increased with an increase in either sulfur content or curing time. The data obtained are discussed in terms of the crosslinking density determined from the Flory–Rehner relation. The effect of thermal aging on such systems was also studied, and the data obtained were compared with those before aging. This investigation led us to conclude that to get an end product that is highly resistant to thermal aging, the system should be cured for a time greater than 30 min with the addition of more than 5 phr sulfur. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1613–1621, 2003
Effect of compatibilization on the performance of biodegradable composites using cotton fiber waste as filler
Authors: Tserki V. , Matzinos P. , Panayiotou C.
Published: March 2003

The usefulness of cotton waste as a source of reinforcing fibers for the preparation of cost‐effective and biodegradable composites has been investigated. Biodegradable polyester (bionolle 3020) is melt‐compounded together with cotton fibers. Maleic anhydride‐grafted bionolle (bionolle‐g‐MA) is used as a compatibilizer. The grafting reaction is carried out in an intensive mixer in the presence of dicumyl peroxide as initiator. The effects of fiber and compatibilizer content as well as graft content are evaluated by mechanical property measurements and scanning electron microscopy. The compatibilizer improved all mechanical properties significantly. Moreover, the water absorption and swelling of composites decreased, while the thermal stability increased slightly. Also, the biodegradation of the polyester bionolle 3020, as well as that of its composites with cotton fibers, were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1825–1835, 2003
Surface modification of polypropylene film by radiation‐induced grafting and its blood compatibility
Authors: Kwon Oh Hyun , Nho Young Chang , Chen Jie
Published: March 2003

To endow blood‐compatible properties onto polypropylene (PP) film, we grafted 2,3‐epoxypropyl methacrylate (EPMA) to PP film with a preirradiation grafting technique and then introduced various functional groups onto the grafted PP film. The EPMA grafting extent was dependent on the absorbed dose, reaction time, and temperature. The reactions of hydroxylation, iminodiacetation, sulfonation, phosphonation, and amination were performed under various conditions to introduce functional groups into the epoxy group of EPMA‐grafted PP films, respectively. We also immobilized heparin on aminated PP film to compare blood compatibility with various functionalized samples. The grafting, functionalization, and heparinization reaction were confirmed by Fourier transform infrared spectroscopy in the attenuated total reflectance mode and electron spectroscopy for chemical analysis. The blood compatibility of various functional groups and heparin‐introduced samples as well as control samples was examined by the determination of platelet adsorption and thrombus formation. For the examination of the blood compatibility of functionalized PP samples, acid citrate dextrose human whole blood and platelet‐rich plasma were used. The amount of the formed thrombus and the adherent platelets on functionalized PP sample surfaces were evaluated by an in vitro method following Imai and Nose's technique and by scanning electron microscopy, respectively. The blood compatibility of various functional‐group‐introduced PP films after grafting was better than that of the PP control. Phosphoric‐acid‐group‐ and heparin‐introduced PP films had especially good blood compatibility. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1726–1736, 2003
Synthesis and properties of side chain cholesteric liquid‐crystalline polyacrylates containing two mesogenic groups
Authors: Zhang Bao‐Yan , Hu Jian‐She , Zang Bao‐Ling , Zhou Ai‐Juan
Published: March 2003

The synthesis of side chain cholesteric liquid‐crystalline polymers containing both 4‐cholesteryl‐4'‐acryloyloxybenzoate (MI) and 4‐methoxyphenyl‐4'‐acryloyloxybenzoate (MII) mesogenic side groups is described. The chemical structures of the obtained monomers and polymers are confirmed by Fourier transform infrared (FTIR) spectroscopy. The phase behavior and optical properties of the synthesized monomers and polymers were investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA). The homopolymer IP reveals a cholesteric phase and VIIP displays a nematic phase. The copolymers IIP–VIP exhibit, respectively, cholesteric oily‐streak texture and focal‐conic texture. The fixation of the helical pitch and oily‐streak texture of the cholesteric phase is achieved by quenching, and polymer films with different reflection colors are obtained. The experimental results demonstrate that the glass transition temperature (Tg) and the melting temperature (Tm) of the copolymers IIP–VIP decrease, whereas the isotropization temperature (Ti) and the mesomorphic temperature range (ΔT) increase with increasing content of mesogenic MII units. TGA results indicate that the temperatures at which 5% mass loss occurred (T5wt%) of all copolymers are >245°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1936–1941, 2003
Use of new diimide–dinaphthols in preparation of novel thermally stable poly(ester–imide)s
Authors: Mehdipour‐Ataei Shahram , Keshavarz Shahriar
Published: March 2003

Reaction of 5‐amino‐1‐naphthol with pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride afforded aromatic diols with preformed imides structure. High temperature solution polycondensation reactions of the obtained diimide–dinaphthols with aromatic and aliphatic diacid chlorides resulted in preparation of nine different poly(ester–imide)s. They were fully characterized and the physical and thermal properties of the obtained polymer were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2168–2172, 2003
Role of the stereosequences of poly(vinyl alcohol) in the rheological properties of syndiotacticity‐rich poly(vinyl alcohol)/water solutions
Authors: Lyoo Won Seok , Seo In Seok , Ji Byung Chul , Kim Joon Ho , Kim Sam Soo , Ghim Han Do , Kim Byoung Chul , Lee Jinwon
Published: March 2003

Syndiotacticity‐rich poly(vinyl alcohols) (s‐PVAs) with various syndiotactic dyad (S‐dyad) contents were prepared by the copolymerization of vinyl pivalate and vinyl acetate with various monomer feed ratios, which was followed by the saponification of copoly(vinyl pivalate/vinyl acetate) to investigate the effect of the stereosequences of s‐PVA on the rheological properties of s‐PVA/water solutions. Through a series of experiments, we identified that the syndiotacticity had a profound influence on the rheological properties of s‐PVA/water solutions. Over a frequency range of 10−1 to 102 rad/s, s‐PVAs with higher S‐dyad contents showed larger values of complex viscosity and storage modulus and more shear thinning at similar molecular weights and degrees of saponification of the polymer, suggesting that poly(vinyl alcohol) molecules were stiffer and more readily oriented as syndiotacticity increased. All the yield stresses of s‐PVA represented positive values, and s‐PVAs with higher syndiotacticity showed higher yield stresses. This suggests that as syndiotacticity increased, more pseudostructures were present in s‐PVA/water solutions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1858–1863, 2003
Interrelation between long‐term viscoelasticity and viscoplastic responses of semicrystalline polymers
Authors: Kontou E. , Spathis G.
Published: March 2003

Two types of linear low‐density polyethylenes, prepared by metallocene catalysts were studied experimentally in terms of differential scanning calorimetry, dynamic mechanical analysis (DMA), and tensile testing. The different comonomer content and the small amounts of long branching in one of the materials studied strongly affect the crystalline distribution and morphology and, consequently, the DMA and tensile experimental data. From the experimental DMA data, the function of relaxation modulus, treated as a material property, is used to describe the corresponding tensile experimental results. A constitutive analysis that considers the viscoelastic path at small strains and the viscoplastic one at high strains proved to be capable of describing the tensile behavior of the materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1942–1950, 2003
Correlation of the material properties of calcium carbonate filled polypropylene with the filler surface energies
Authors: Ansari Deeba M. , Price Gareth J.
Published: March 2003

The physical and mechanical properties of polypropylene (PP) were measured and compared with those of PP composites filled with calcium carbonate modified with sodium polyacrylate, stearic acid, or both. The variations in the mechanical properties showed a high degree of correlation with the surface energies of the fillers, as determined by inverse gas chromatography. The results confirmed the usefulness of inverse gas chromatography for characterizing the compatibility of polymer–filler combinations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1951–1955, 2003
Crystallization kinetics and melting behavior of nylon 10,10 in nylon 10,10–montmorillonite nanocomposites
Authors: Zhang Guosheng , Yan Deyue
Published: March 2003

The crystallization kinetics and melting behavior of nylon 10,10 in neat nylon 10,10 and in nylon 10,10–montmorillonite (MMT) nanocomposites were systematically investigated by differential scanning calorimetry. The crystallization kinetics results show that the addition of MMT facilitated the crystallization of nylon 10,10 as a heterophase nucleating agent; however, when the content of MMT was high, the physical hindrance of MMT layers to the motion of nylon 10,10 chains retarded the crystallization of nylon 10,10, which was also confirmed by polarized optical microscopy. However, both nylon 10,10 and nylon 10,10–MMT nanocomposites exhibited multiple melting behavior under isothermal and nonisothermal crystallization conditions. The temperature of the lower melting peak (peak I) was independent of MMT content and almost remained constant; however, the temperature of the highest melting peak (peak II) decreased with increasing MMT content due to the physical hindrance of MMT layers to the motion of nylon 10,10 chains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2181–2188, 2003
Analysis of the isothermal crystallization of isotactic polypropylene nucleated with sorbitol derivatives
Authors: Marco C. , Ellis G. , Gómez M. A. , Arribas J. M.
Published: March 2003

The isothermal crystallization kinetics of isotactic polypropylene (iPP) and iPP nucleated with the sorbitol derivatives 1,3:2,4‐bis(4‐methyldibenzylidene)sorbitol and 1,3:2,4‐bis(3,4‐dimethylbenzylidene)sorbitol was studied, along with the subsequent melting behavior, as a function of the nucleating agent concentration. The influence of the agents on the crystallization rate, crystallization temperature, and crystallization range was examined. The isothermal crystallization temperature increased, along with the crystallization rate, with increasing nucleating agent concentration. The maximum effect of the additives occurred at concentrations of 0.3% or greater. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2261–2274, 2003
Development of an additive equation for predicting the electrical conductivity of carbon‐filled composites
Authors: Clingerman Matthew L. , Weber Erik H. , King Julia A. , Schulz Kirk H.
Published: March 2003

The electrical conductivity of polymeric materials can be increased by the addition of carbon fillers. The resulting composites can be used in applications such as electrostatic dissipation and interference shielding. Electrical conductivity models are often proposed to predict the conductivity behavior of these materials. The electrical conductivity of carbon‐filled polymers was studied here by the addition of three single fillers to nylon 6,6 and polycarbonate in increasing concentrations. The fillers used in this project were carbon black, synthetic‐graphite particles, and milled pitch‐based carbon fibers. Materials were extruded and injection‐molded into test specimens, and then the electrical conductivity was measured. Additional material characterization tests included optical microscopy for determining the filler aspect ratio and orientation. The filler and matrix surface energies were also determined. An updated model developed by Mamunya and others and a new additive model (including the constituent conductivities, filler volume fraction, percolation threshold, constituent surface energies, filler aspect ratio, and filler orientation) fit the electrical conductivity results well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2280–2299, 2003
Study of sorption/desorption of water and organic vapors on poly(ethylene maleate)‐based sensor‐coating materials using an automated gravimetric analyzer
Authors: Dubey Vinita , Kuthe Sandeep , Saxena Chhaya , Jaiswal Devendra K.
Published: March 2003

Hydrophobic comonomers bisphenol‐A and hexafluorobisphenol‐A were incorporated as diol components in the sensor‐coating material poly(ethylene maleate) (PEM), resulting in modified polymers, HCPEM and HFPEM, respectively. To assess the suitability of these polymers as sensor interfaces, the sorption/desorption isotherms and kinetics of water and a range of volatile organic vapors were obtained over the entire relative pressure range of 0.1 to 1.0, using an automated intelligent gravimetric sorption analyzer. The extent and rate of sorption of organic vapors were higher in the modified polymers compared to those of the parent polymer. Sorption hysteresis was observed at high relative pressures, especially with water and other hydrogen‐bonded polar organic vapors. Polarizable vapors like toluene and benzene were sorbed more than nonpolarizable cyclohexane vapors. The sorption results were interpreted in terms of semiempirical models based on concepts of thermodynamic interaction parameter, partition coefficient, and linear solvation energy relationship. The study reveals the potential of sorption/desorption isotherms and kinetics in characterizing the sorption properties of coating materials that are used as an interface in acoustic wave sensors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1760–1767, 2003
Interface development and encapsulation in simultaneous coinjection molding. I. Two‐dimensional modeling and formulation
Authors: Li C. T. , Isayev A. I.
Published: March 2003

In the coinjection‐molding process two polymers are injected into a mold sequentially or simultaneously. During the process one polymer melt forms the skin and the other forms the core, resulting in an encapsulated sandwich structure. In an attempt to develop a process model and simulation of simultaneous coinjection molding, along with the interface treatment a theoretical approach, physical model, and numerical algorithm were formulated based on the Hele–Shaw approximation. A detailed picture of the dynamics and kinematics of the interface evolution, providing a description of the multilayer flow and interface development during the multicomponent injection‐molding process, information typically lacking in the available literature, is systematically presented. Based on the developed numerical simulation code, the moldability of various material combinations can be evaluated, which is required for process optimization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2300–2309, 2003
Thermal degradation studies on rigid polyurethane foams blown with pentane
Authors: Pielichowski Krzysztof , Kulesza Kamil , Pearce Eli M.
Published: March 2003

The effect of sodium dihydrogenphosphate, trisodium pyrophosphate, and sodium aluminocarbonate on the thermal decomposition of rigid polyurethane (PUR) foams, based on diphenylmethane‐4,4‐diisocyanate, diphenyl‐2,2‐propane‐4,4‐dioxyoligo(ethylene oxide), and oxyalkylenated toluene‐2,6‐diamine, blown with pentane, was studied. Thermogravimetric (TG) data have shown that there is a stabilization effect of additives in the initial stage of degradation, both in nitrogen and air atmosphere, and the decomposition proceeded in two steps up to 600°C. Results of the kinetic analysis by the isoconversional methods of Ozawa–Flynn–Wall and Friedman yielded values of (apparent) activation energy (Ea) and preexponential factor (A). For phosphate‐stabilized PUR samples, Ea remained stable over a broad area of the degree of conversion, while for carbonate‐containing sample two regions of Ea were observed. Further advanced kinetic analysis by a nonlinear regression method revealed the form of kinetic function that was the best approximation for experimental data—for a two‐stage consecutive reaction the first step was the Avrami–Erofeev nucleation‐dependent model, and the second step was a chemical reaction (1st or nth order) model. The integrated thermogravimetric (TG)/Fourier transform infrared (FTIR) technique probed the thermal degradation of modified PURs by analyzing the evolved gases. The solid residue remaining at different temperatures was identified by diffuse reflection FTIR (Kubelka–Munk format). The complex thermal behavior was discussed on the basis of the obtained results—it can be shown that the global stabilization effect is a multistage process whose initial conditions are of critical importance in governing the nature of the entire process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2319–2330, 2003
Gamma‐ray irradiation effect of polyethylene on dimaleimides as a class of new multifunctional monomers
Authors: Jae Lee In , Wook Choi Ho , Chang Nho Young , Hack Suh Dong
Published: March 2003

Multifunctional monomers, m‐xylylenedimaleimide, p‐phenylenedimaleimide, m‐phenylenedimaleimide, and p‐phenylenedinadimide, all of which have maleimide groups, were synthesized to increase thermal and radiation stabilities. The synthesized multifunctional monomers showed good compatibility with low‐density polyethylene (LDPE). Mixtures of LDPE and these multifunctional monomers were irradiated with γ‐rays from a Co‐60 source at room temperature in a nitrogen atmosphere. The absorbed dose ranged from 0 to 160 KGy. Among these multifunctional monomers, m‐xylylenedimaleimide was the best in gel fraction enhancement. Crosslinked LDPE with m‐xylylenedimaleimide displayed a higher modulus than that of crosslinked LDPE with triallyl cyanurate. For the elongation property, LDPE with m‐xylylenedimaleimide as a multifunctional monomer showed better results than that with commercial multifunctional monomers such as triallyl cyanurate (TAC) and trimethylol propane triacrylate (TMPTA). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2339–2345, 2003
Tannins/melamine–urea–formaldehyde (MUF) resins substitution of chrome in leather and its characterization by thermomechanical analysis
Authors: Simon C. , Pizzi A.
Published: March 2003

A new sulfonated melamine–urea–formaldehyde (MUF) resin of relatively low melamine content, prepared according to a sequential formulation, has been shown to be highly effective when coupled with different natural vegetable tannins to produce leather with the same good characteristics of leather prepared with chrome salts. In particular, the antishrinkage effectiveness of the leather prepared according to the new approach is comparable to that obtained with chrome tanned leathers. The comparison of the traditional leather shrinkage temperatures test method with a new thermomechanical analysis (TMA) test method in tension yields thermograms presenting three major modulus of elasticity (MOE) peaks. These are closely connected to molecular level phenomena determining the shrinkage temperature of leather. The three determining parameters appear to be as follows: (1) The average value of the temperatures at which the three MOE peaks occur: the higher the value of this average, the lower is the shrinkage of leather. (2) The average of maximum MOE values of the TMA peaks: the higher this average is, the better is the leather in regard to antishrinkage effectiveness. This means the leather maximum MOE at each peak is a measure of the resistance to the contraction force induced by heat. (3) The relative intensity of the first TMA peak in relation to the second: the higher the value of the MOE for the first TMA peak is in relation to the second peak, the lower the leather shrinkage appears to be. However, it has not been possible to better define or quantify this latter effect. This new TMA test method in tension has also yielded a mathematical relationship correlating the thermogram peak temperatures and MOE averages with the traditional shrinkage temperature to a high degree of confidence. A previous TMA test method, in compression, has proven to yield more problematic and finally not very reliable results when one needs to apply it to a wide variety of different cases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1889–1903, 2003
A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index
Authors: Munné A. , Prat N. , Solà C. , Bonada N. , Rieradevall M.
Published: March 2003

An index of riparian quality useful for the management of streams and rivers is presented. The purpose of the index is to provide managers with a simple method to evaluate riparian habitat quality. The index is easy to calculate and can be used together with any other index of water quality to assess the ecological status of streams and rivers. It may also be a useful tool for defining ‘high ecological status’ under the EC Water Framework Directive.

The index, named QBR, is based on four components of riparian habitat: total riparian vegetation cover, cover structure, cover quality and channel alterations. It also takes into account differences in the geomorphology of the river from its headwaters to the lower reaches. These differences are measured in a simple, quantitative way. The index score varies between 0 and 100 points.

The QBR index is calculated in the field through a two‐sided A4 page form that may be completed in 10 min.

The development of the QBR index included trials in four Mediterranean stream catchments in Catalonia (NE Spain). Seventy‐two sampling sites were assessed and results were used to test the index.

No taxonomic expertise is needed to apply the index, although some knowledge of local flora is required to differentiate between native and non‐native tree species.

These results show that the QBR index may be used despite regional differences in plant communities. The quality ranges obtained when the index is applied are not heavily influenced by observers at the same site.

At present, the index is being used by different research teams and tested in a comparative study of 12 watersheds along the Mediterranean Spanish coast.

It is expected that the QBR index may be adapted for use in other geographical areas in temperate and semi‐arid zones without changes in the index rationale.

Copyright © 2002 John Wiley & Sons, Ltd.
Recruitment of intra‐ and extracardiac cells into the myocardial lineage during mouse development
Authors: Kruithof Boudewijn P.T. , van den Hoff Maurice J.B. , Tesink‐Taekema Sabina , Moorman Antoon F.M.
Published: March 2003

The tubular heart differentiates from the bilateral cardiac fields in the splanchnic mesoderm. The expression of smooth muscle proteins has been shown to accompany the early phases of cardiac muscle formation. In this study we show that during elongation of the arterial pole of the mouse linear heart tube, α‐smooth muscle actin (α‐Sma) expression extends in the area that has been shown to become recruited into the myocardial lineage, but does not yet express myocardial markers. These data suggest that α‐Sma identifies mesodermal cells that during subsequent development will be recruited into the myocardial lineage. Myocardium formation is not only observed at the arterial pole, but also at the venous pole and in the intracardiac mesenchyme. This results in the formation of the caval and pulmonary myocardium, the smooth‐walled atrial myocardium, the myocardial atrioventricular septum, and the myocardial outlet septum. To determine whether recruitment into the myocardial lineage also takes place in these regions, the spatiotemporal pattern of expression of α‐Sma and of the myocardial markers sarcoplasmatic reticulum calcium ATPase (Serca2a), α‐myosin heavy chain (Mhc), and β‐Mhc were examined. We show that prior to the expression of myocardial markers, α‐Sma is expressed in these regions, which suggests that these mesodermal cells become recruited into the cardiac lineage after formation of the linear heart tube. Anat Rec Part A 271A:303–314, 2003. © 2003 Wiley‐Liss, Inc.
Hydralazine may induce autoimmunity by inhibiting extracellular signal–regulated kinase pathway signaling
Authors: Deng Chun , Lu Qianjin , Zhang Zhiyong , Rao Tharaknath , Attwood John , Yung Raymond , Richardson Bruce
Published: March 2003

Objective

To determine whether hydralazine might decrease DNA methyltransferase (DNMT) expression and induce autoimmunity by inhibiting extracellular signal–regulated kinase (ERK) pathway signaling.

Methods

The effect of hydralazine on DNMT was tested in vitro using enzyme inhibition studies, and in vivo by measuring messenger RNA (mRNA) levels and enzyme activity. Effects on ERK, c‐Jun N‐terminal kinase, and p38 pathway signaling were tested using immunoblotting. Murine T cells treated with hydralazine or an ERK pathway inhibitor were injected into mice and anti‐DNA antibodies were measured by enzyme‐linked immunosorbent assay.

Results

In vitro, hydralazine did not inhibit DNMT activity. Instead, hydralazine inhibited ERK pathway signaling, thereby decreasing DNMT1 and DNMT3a mRNA expression and DNMT enzyme activity similar to mitogen‐activated protein kinase kinase (MEK) inhibitors. Inhibiting T cell ERK pathway signaling with an MEK inhibitor was sufficient to induce anti–double‐stranded DNA antibodies in a murine model of drug‐induced lupus, similar to the effect of hydralazine.

Conclusion

Hydralazine reproduces the lupus ERK pathway signaling abnormality and its effects on DNMT expression, and inhibiting this pathway induces autoimmunity. Hydralazine‐induced lupus could be caused in part by inducing the same ERK pathway signaling defect that occurs in idiopathic lupus.