bluuebunny/crossref_metadata_2025 huggingface dataset:
Broad thumbs and halluces with deafness: A patient with Keipert syndrome
Authors: Reardon William , Hall Christine M.
Published: March 2003

Clinical, radiological, and audiological features are described in a boy whose condition closely parallels the profile of patients previously described with Keipert syndrome. This case represents the fourth report of this rare disorder. © 2003 Wiley‐Liss, Inc.
Prenatal diagnosis of a trisomy 7/maternal uniparental heterodisomy 7 mosaic fetus
Authors: Bilimoria Karl Y. , Rothenberg Jeffrey M.
Published: March 2003

Chromosomal segregation anomalies often result in trisomy of a single chromosome, which can lead to a disastrous phenotype in the fetus. However, this trisomy is often “rescued” via loss of one of the triploid chromosomes. Depending on which chromosome is eliminated in the rescue, a condition known as uniparental disomy may arise where both copies of a particular chromosome pair originate from the same parent. Here we describe the case of a 32‐year‐old woman who was prenatally diagnosed with trisomy 7 mosaicism via amniocentesis. Forty‐one percent of the colonies analyzed displayed trisomy 7 (two maternal chromosomes and one paternal chromosome); whereas, 59% of the colonies demonstrated a normal, disomic karyotype. Further analysis revealed that the “normal” cell lineage displayed maternal uniparental heterodisomy. Chorionic villus tissue was homogenously trisomic, and cord blood cells were uniformly disomic. This is the first case of trisomy 7/uniparental disomy 7 mosaic fetus reported in the literature. It is important to note that not all such cases will result in lethality or a fetus with major anatomic, developmental, or cognitive abnormalities. In addition, the benefit of pre‐ and post‐screening test counseling and support is discussed in reference to fetuses with chromosomal abnormalities in general and our case in particular. © 2003 Wiley‐Liss, Inc.
Unexpected survival in a case of prenatally diagnosed non‐mosaic trisomy 22: Clinical report and review of the natural history
Authors: Tinkle Brad T. , Walker Martha E. , Blough‐Pfau Ruthann I. , Saal Howard M. , Hopkin Robert J.
Published: March 2003

Over 30 cases of complete non‐mosaic trisomy 22 have been reported in the literature in the last 20 years [Crowe et al., 1997: Am J Med Genet 71:406–413]. Twenty‐two infants were liveborn with an average life expectancy of four days. Of these, nine survived beyond the first two weeks of life. The life span ranged from minutes to 3 years of age. We report a case of an infant diagnosed prenatally with complete non‐mosaic trisomy 22. Options such as aggressive medical/surgical intervention or limiting interventions to symptomatic care including home hospice were discussed openly. Given this information, the family elected to provide minimal supportive measures with pediatric hospice. The infant lived for 2 months with her family before her death. Numerous medical and surgical complications are associated with this disorder. Both the family and the medical team must be prepared for in utero fetal demise, stillbirth, or for limited life expectancy. Proper management, therefore, depends upon an understanding of the diagnosis. © 2003 Wiley‐Liss, Inc.
Elucidating the role of genetic factors in smoking behavior and nicotine dependence
Authors: Lerman Caryn , Berrettini Wade
Published: March 2003

Despite over a decade of intensive tobacco control efforts, a substantial proportion of the world's population continues to smoke. With advances in molecular biology and genomics technology, attention is focusing on the genetic basis of addiction to nicotine. The hope is that by better understanding the biology of nicotine addiction, novel prevention and cessation strategies can be developed and targeted to individuals most likely to benefit. This article provides an overview of currently available data from genetics research on smoking behavior and discusses study design issues to be addressed to make progress in this line of research. © 2003 Wiley‐Liss, Inc.
Suicide and serotonin: Study of variation at seven serotonin receptor genes in suicide completers
Authors: Turecki G. , Sequeira A. , Gingras Y. , Séguin M. , Lesage A. , Tousignant M. , Chawky N. , Vanier C. , Lipp O. , Benkelfat C. , Rouleau G.A.
Published: March 2003

Suicide is an important public health problem, accounting for a significant proportion of total mortality among young people, particularly males. There is growing and consistent evidence suggesting that genetic factors play an important role in the predisposition to suicide. Based on several lines of evidence supporting a reduced serotonergic neurotransmission in subjects who committed suicide, we investigated variation at genes that code for serotonin receptor 1B (5‐HTR1B), 1Dα (5‐HTR1Dα), 1E (5‐HTR1E), 1F (5‐HTR1F), 2C (5‐HTR2C), 5A (5‐HTR5A), and 6 (5‐HTR6) in a total sample of 106 suicide completers and 120 normal controls. No differences were observed in allelic or genotypic distributions between groups for any of the loci investigated. Moreover, further analysis according to suicide method or psychopathology also failed to reveal differences between groups. Our results do not support a substantial role of these serotonergic receptors in suicide completion. © 2003 Wiley‐Liss, Inc.
Allelic variation in serotonin transporter function associated with the intensity dependence of the auditory evoked potential
Authors: Strobel A. , Debener S. , Schmidt D. , Hünnerkopf R. , Lesch K‐P. , Brocke B.
Published: March 2003

The intensity dependence of the auditory evoked potential (AEP) has been suggested as an indicator of central serotonergic function, a strong intensity dependence presumably reflecting low serotonergic activity. As individual differences in serotonergic neurotransmission can be accounted for in part by genetic variation in genes of the serotonergic pathway, we investigated whether a functional polymorphism in the promoter region of the serotonin transporter gene (5‐HTTLPR) is associated with the AEP intensity dependence. Because dopaminergic influences on the intensity dependence have also been reported, we furthermore explored the role of a functional polymorphism in the dopamine D4 receptor gene (DRD4 exon III) in the modulation of the AEP intensity dependence. AEPs to tones of six intensity levels were recorded from 60 healthy young individuals, and N1/P2 linear as well as median slopes at central electrode sites were computed as measures of the AEP intensity dependence. Analyses of variance showed that there was a significant effect of the 5‐HTTLPR on the AEP intensity dependence. Individuals with the ll genotype exhibited a stronger intensity dependence compared to individuals with the ls genotype. This effect was even more pronounced when DRD4 exon III was considered in the analyses. In conclusion, these findings provide further evidence for a role of serotonergic neurotransmission in the modulation of the AEP intensity dependence. The results also point to possible dopaminergic influences on the AEP intensity dependence. © 2003 Wiley‐Liss, Inc.
White matter tract alterations in fragile X syndrome: Preliminary evidence from diffusion tensor imaging
Authors: Barnea‐Goraly Naama , Eliez Stephan , Hedeus Maj , Menon Vinod , White Christopher D. , Moseley Michael , Reiss Allan L.
Published: March 2003

Fragile X syndrome, the most common form of hereditary mental retardation, causes disruption in the development of dendrites and synapses, the targets for axonal growth in the central nervous system. This disruption could potentially affect the development, wiring, and targeting of axons. The current study utilized diffusion tensor imaging (DTI) to investigate whether white matter tract integrity and connectivity are altered in fragile X syndrome. Ten females with a diagnosis of fragile X syndrome and ten, age matched, female control subjects underwent diffusion weighted MRI scans. A whole brain analysis of fractional anisotropy (FA) values was performed using statistical parametric mapping (SPM). A follow‐up, regions‐of‐interest analysis also was conducted. Relative to controls, females with fragile X exhibited lower FA values in white matter in fronto‐striatal pathways, as well as in parietal sensory‐motor tracts. This preliminary study suggests that regionally specific alterations of white matter integrity occur in females with fragile X. Aberrant white matter connectivity in these regions is consistent with the profile of cognitive and behavioral features of fragile X syndrome, and potentially provide additional insight into the detrimental effects of suboptimal levels of FMRP in the developing brain. © 2003 Wiley‐Liss, Inc.
Modest evidence for linkage and possible confirmation of association between NOTCH4 and schizophrenia in a large veterans affairs cooperative study sample
Authors: Skol A.D. , Young K.A. , Tsuang D.W. , Faraone S.V. , Haverstock S.L. , Bingham S. , Prabhudesai S. , Mena F. , Menon A.S. , Yu Chang‐En , Rundell Paul , Pepple J. , Sauter F. , Baldwin C. , Weiss D. , Collins J. , Keith T. , Boehnke M. , Schellenberg G.D. , Tsuang M.T.
Published: March 2003

Wei and Hemmings [2000: Nat Genet 25:376–377], using 80 British parent–offspring trios, identified a number of NOTCH4 variants and haplotypes that showed statistically significant evidence of association to schizophrenia. Specifically, the 10 repeat allele of a (CTG)n marker and the 8 repeat allele of a (TAA)n marker demonstrated excess transmission to affected individuals; SNP21 and haplotypes SNP2‐(CTG)n and SNP12‐SNP2‐(CTG)n also showed significant associations. In an attempt to replicate these findings, we tested for linkage and association between the same five markers used by Wei and Hemmings in 166 families collected from a multi‐center study conducted by the Department of Veterans Affairs (DVA) Cooperative Study Program (CSP). The families include 392 affected subjects (schizophrenia or schizoaffective disorder, depressed) and 216 affected sibling pairs. The families represent a mix of European Americans (n = 62, 37%), African Americans (n = 60, 36%), and racially mixed or other races (n = 44, 27%). We identified moderate evidence for linkage in the pooled race sample (LOD = 1.25) and found excess transmission of the 8 (P = 0.06) and 13 (P = 0.04) repeat alleles of the (TAA)n marker to African American schizophrenic subjects. The 8 and 13 repeat alleles were previously identified to be positively associated with schizophrenia by Wei and Hemmings [2000: Nat Genet 25:376–377] and Sklar et al. [2001: Nat Genet 28:126–128], respectively. © 2003 Wiley‐Liss, Inc.
Family‐based and case‐control association studies of catechol‐O‐methyltransferase in attention deficit hyperactivity disorder suggest genetic sexual dimorphism
Authors: Qian Qiujin , Wang Yufeng , Zhou Rulun , Li Jun , Wang Bing , Glatt Stephen , Faraone Stephen V.
Published: March 2003

Attention deficit hyperactivity disorder (ADHD) is the most common childhood‐onset behavioral disorder. Boys are more often affected than girls. Family, twin, and adoption studies have supported a strong genetic basis. Some studies show that a catechol‐O‐methyltransferase (COMT) polymorphism affecting enzyme activity was associated with personality characteristics and diseases, such as novelty‐seeking personality, substance abuse, and heroin addiction, whose features are similar to ADHD or are associated with ADHD. These findings suggest that the COMT gene may be a candidate gene for ADHD. TDT, HHRR, and case‐control association studies were conducted within a sample of 202 nuclear ADHD families, 340 ADHD cases, and 226 controls in the Han Chinese population. Diagnoses and ADHD subtypes were ascertained according to DSM‐IV criteria using American Clinical Diagnostic Interviewing Scales. The HHRR analysis suggested that the low enzyme‐activity COMT Met allele was preferentially transmitted to ADHD boys (160 trios, χ2 = 3.858, P = 0.05, df = 1) but not girls. This association is particularly pronounced among male ADHD probands without any comorbidity (50 trios, HHRR: χ2 = 5.128, P = 0.024, df = 1; TDT: χ2 = 4.558, P = 0.033, df = 1), especially the ADHD‐I subtype (32 trios, HHRR: χ2 = 5.792, P = 0.016, df = 1; TDT: χ2 = 5.333, P = 0.021, df = 1). The case‐control study revealed that the Val allele was more frequent in females meeting ICD‐10 or DSM‐IV criteria for ADHD than in female controls (86 and 79.5%, respectively, χ2 = 4.059, P = 0.044, df = 1). Although these results suggest the COMT gene exerts some influence on the risk for ADHD in the Han Chinese population, given the potential for Type I error, these findings require replication before drawing definitive conclusions. © 2003 Wiley‐Liss, Inc.
NOTCH4 and the frontal lobe in schizophrenia
Authors: Wassink Thomas H. , Nopoulos Peggy , Pietila Jennifer , Crowe Raymond R. , Andreasen Nancy C.
Published: March 2003

NOTCH4 is a developmentally expressed gene recently reported to be in linkage disequilibrium (LD) with schizophrenia. We investigated this finding in our sample of subjects, focusing on an exonic (CTG)n polymorphism, examining not only the association of this polymorphism with the disease phenotype, but also its effect on frontal lobe brain morphology and cognitive function in both affected individuals and a psychiatrically normal comparison group. While we did not find any association or LD with schizophrenia, we identified striking effects of NOTCH4 variability on the trait measures. Within the respective schizophrenia and comparison groups, NOTCH4 allelic variability was correlated with differences in measures of frontal lobe cognitive performance and frontal lobe brain tissue volumes that were intuitively congruent. These within‐group effects, however, were in opposite directions across groups. These findings may reflect the interaction of NOTCH4 with the underlying genetic and phenotypic complexity that characterizes both schizophrenia and normal cognition and brain development. © 2003 Wiley‐Liss, Inc.
Mechanisms of force and power production in unsteady ricochetal brachiation
Authors: Usherwood James R. , Larson Susan G. , Bertram John E.A.
Published: March 2003

Brachiators travel by swinging beneath handholds, and it is not obvious how these animals manage to accelerate and decelerate in a horizontal direction, especially when moving rapidly. Most previous analyses focused on brachiation in highly constrained laboratory conditions that induced steady‐state locomotion. Emerging understanding of brachiation suggests that much of gibbon locomotory behavior and morphology must be considered within the context of the complexities of the natural environment: the forest canopy is three‐dimensional, with high variation in handhold availability and properties. The goal of this paper is to quantify the active mechanisms by which gibbons can dynamically control their velocity.

Force production and kinematics were analyzed from a white‐handed gibbon Hylabates lar during ricochetal brachiation. Both the mechanisms of force production and power input may be inferred for accelerating and decelerating brachiation by combining force data with kinematics. Examples of steady‐state, accelerating, and decelerating ricochetal brachiation are highlighted.

Gibbons are able to produce net horizontal impulses by releasing early (resulting in a loss of potential energy, but an accelerating horizontal impulse) or delaying release (associated with an increase in potential energy, and a decelerating horizontal impulse).

Torque about the shoulder, leg‐lifting (or dropping), and elbow flexing (or straightening) are discussed as potential mechanisms for controlling energy within the brachiating system. Of these possibilities, leg‐lifting and arm‐flexing were observed as mechanisms of adding mechanical energy. Net energy loss, and substantial torques about the shoulder, were not observed. Am J Phys Anthropol 120:364–372, 2003. © 2003 Wiley‐Liss, Inc.
Macroscopic and microscopic analyses of linear enamel hypoplasia in Plio‐Pleistocene South African hominins with respect to aspects of enamel development and morphology
Authors: Guatelli‐Steinberg Debbie
Published: March 2003

This study uses macroscopic and microscopic methods to analyze the expression of linear enamel hypoplasia (LEH) in Plio‐Pleistocene South African hominins. LEH is a developmental defect of enamel that is used in many anthropological contexts as a physiological stress indicator. Previous research has not settled the question as to whether differences in LEH expression exist between Paranthropus and Australopithecus and if they exist, to what extent these differences might be explained simply by taxonomic differences in enamel development and morphology rather than by differential stress experience. In this study, the analysis of LEH is conducted with respect to differences between Paranthropus and Australopithecus in aspects of enamel development and morphology that are thought to influence LEH expression. Two factors impacting LEH expression are considered: the duration of enamel formation, and the spacing of perikymata. It is predicted that if the first factor strongly influences the expression of LEH, then there should be fewer defects per tooth in Paranthropus because of its abbreviated crown formation spans (and fast extension rates) relative to Australopithecus. It is also predicted that because Australopithecus has more densely packed perikymata in comparable regions of the crown than Paranthropus, this taxon should, on average, have narrower defects than Paranthropus. To address these questions, 200 Australopithecus and 137 Paranthropus teeth were examined for LEH, and the analysis of defect width with respect to perikymata spacing was conducted on tooth impressions examined under a scanning electron microscope using INCA (Oxford Instruments) measurement software. Data support the first prediction: Australopithecus does have significantly more defects per canine tooth than Paranthropus. Data do not support the second prediction in large part because several Australopithecus specimens have wide groove defects in which perikymata are not visible and enamel is irregular. Such wide grooves are not predicted by perikymata spacing such that alternative explanations, including taxonomic differences in ameloblast sensitivity and the duration/severity of disruptions to enamel growth, must be considered. Am J Phys Anthropol 120:309–322, 2003. © 2003 Wiley‐Liss, Inc.
Organische Template zur Formgebung anorganischer Materialien
Authors: van Bommel Kjeld J. C. , Friggeri Arianna , Shinkai Seiji
Published: March 2003

Die Wissenschaft wird wie die Kunst und Architektur von den faszinierenden Formen und Mustern der Natur beeinflusst. Die Mechanismen, die zu organischen, anorganischen und bioorganischen Strukturen führen, wurden in der Physik und Biologie intensiv erforscht, aber auch die Chemie interessiert sich für die Konzepte, auf denen die Bildung regelmäßiger Formen beruht. Während in der Organischen und insbesondere der Supramolekularen Chemie die Synthese großer Überstrukturen bereits früh mit großem Erfolg umgesetzt wurde, gelang es innerhalb der Anorganischen Chemie erst in den letzten Jahren, Verfahren zur Steuerung der Struktur anorganischer Materialien auf mikroskopischer und nanoskopischer Ebene zu entwickeln. Einer der erfolgreichsten Ansätze zur Herstellung anorganischen Strukturen beruht dabei auf der Verwendung organischer und bioorganischer Template, einer Methode, deren Leistungsfähigkeit in diesem Aufsatz vorgestellt werden soll.
Efficient Degradation of Organic Pollutants by Using Dioxygen Activated by Resin‐Exchanged Iron(II) Bipyridine under Visible Irradiation
Authors: Ma Wanhong , Li Jing , Tao Xia , He Ju , Xu Yiming , Yu Jimmy C. , Zhao Jincai
Published: March 2003

Effektive Aktivierung von molekularem Sauerstoff bewirkt der hier beschriebene [FeII(bpy)3]‐Amberlit‐Photokatalysator, der auf sichtbares Licht anspricht [Gl. (1)]. Das Fernziel, nämlich eine grüne Technologie zur Schadstoffdekontamination, ist damit einen großen Schritt näher gerückt.
Titelbild: Aluminum Dihydroxide with Terminal OH Groups: An Unprecedented Congener of Boronic Acid (Angew. Chem. 10/2003)
Authors: Bai Guangcai , Peng Ying , Roesky Herbert W. , Li Jiyang , Schmidt Hans‐Georg , Noltemeyer Mathias
Published: March 2003

Der Fang der Woche ist eine ungewöhnliche Aluminiumverbindung der Formel [LAl(OH)2], die durch Hydrolyse von [LAlI2] in einem Toluol/Ammoniak(fl.)‐Zweiphasensystem hergestellt wurde. Gemäß der Festkörperstruktur liegt ein Dimer mit schwachen Wasserstoffbrücken vor; einer Analyse des elektrostatischen Potentials zufolge greifen Elektrophile bevorzugt an den Sauerstoffpositionen an, und die π‐Elektronendichte erhöht sich bei der Dimerisierung. Mehr Details finden Sie in der Zuschrift von H. W. Roesky et al. auf S. 1164 ff.
Preparation and characterization of modified starch‐based plastic film reinforced with short pulp fiber. I. Structural properties
Authors: Kim Dae‐Hyun , Na Seong‐Ki , Park Jong‐Shin
Published: March 2003

Native corn starch‐ and hydroxypropylated starch (HPS‐) based plastic films were prepared using the short pulp fiber as the reinforcement and the glycerol as the plasticizer. Starch (or HPS) films showed different X‐ray diffraction patterns with the A‐type of native corn starch powder. The crystallinity of films increased with pulp content, but decreased with glycerol content and degree of substitution by hydroxypropylation. Also, the intensity of peaks at 2θ = 15.3 and 17.3° decreased with glycerol content and degree of substitution. The water uptake of films as a function of the relative humidity decreased with pulp content and degree of substitution by hydroxypropylation, but increased with glycerol content. Differential scanning calorimetry (DSC) thermograms showed that the glass transition temperature of films decreased and the endothermic peaks at the melting temperature broadened due to the plasticizing effect and the decrease of the crystallinity, which were caused by the addition of glycerol and the hydroxypropylation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2100–2107, 2003
Preparation and characterization of modified starch‐based plastic film reinforced with short pulp fiber. II. Mechanical properties
Authors: Kim Dae‐Hyun , Na Seong‐Ki , Park Jong‐Shin
Published: March 2003

Native corn starch‐ and hydroxypropylated starch (HPS‐) based plastic films were prepared using the short pulp fiber as the reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the strain and stress at break and elastic modulus increased with pulp content. With glycerol content, the strain at break increased considerably, but the breaking stress and elastic modulus decreased. And the stress–strain curves showed that the brittleness problem of films was overcome by the pulp, glycerol, and water content. The hydroxypropyl starch films showed results similar to those of the native starch films. The results of the three‐point bending test showed that maximum deflection, flexural strength, and specific work increased with pulp content, but the flexural modulus was the highest at a pulp content of 20%. And with the glycerol content, the maximum deflection and specific work of rupture increased, but the bending elastic modulus decreased. The hydroxypropyl starch films showed results similar to those of native starch films as far as the maximum deflection and flexural strength were concerned, but the bending elastic modulus and specific work of the hydroxypropyl starch films were considerably lower than those of starch films. So it was concluded that the flexibility of films was improved by the hydroxypropylation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2108–2117, 2003
pH‐sensitive dimethylaminoethyl methacrylate (DMAEMA)/acrylamide (AAm) hydrogels: Synthesis and adsorption from uranyl acetate solutions
Authors: Yıldız Berna , Işık Belma , Kış Mehmet , Birgül Özgen
Published: March 2003

A random copolymer of dimethylaminoethyl methacrylate (DMAEMA) and acrylamide(AAm) [poly(DMAEMA/AAm)], with a pH‐sensitive character, was prepared by a redox polymerization method. Increasing the DMAEMA content of the gel, the pH, and the ionic strength of the solution decreased the swelling ratios of the hydrogels. The adsorption of poly(DMAEMA/AAm) hydrogels from uranyl acetate (UA) solutions was studied at different pHs. The adsorption capacity of hydrogels increased from 200 to 1200 mg of UA per gram of dry hydrogel with increasing pH of the adsorption solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2028–2031, 2003
Synthesis of poly(dodecyl methacrylate)s and their drag‐reducing properties
Authors: Ma Yuxin , Zheng Xilai , Shi Fengmei , Li Yue , Sun Shoujia
Published: March 2003

Dodecyl methacrylate was synthesized as the intermediate monomer for the preparation of poly(dodecyl methacrylate)s, which were synthesized with emulsion polymerization techniques. The intrinsic viscosities were measured, and the viscosity‐average molecular weights were calculated. Polymers of dodecyl methacrylate with ultrahigh molecular weights (viscosity‐average molecular weight > 107) were synthesized through orthogonal experiments. The drag‐reduction properties of these polymers were studied in kerosene. The drag‐reducing behavior of these polymers exhibited a strong dependence on the molecular weight and Reynolds number, and these polymers could be used as effective oil‐soluble drag reducers and had good shear stabilities. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1622–1626, 2003
Effect of processing conditions on mechanical and viscoelastic properties of biocomposites
Authors: Ali R. , Iannace S. , Nicolais L.
Published: March 2003

To study the effects of processing conditions on the viscoelastic and mechanical properties of biodegradable composites, we prepared several composites based on sisal fibers and biodegradable polymers. The effects of processing conditions such as the speed of rotation, temperature, and time of mixing were investigated. The mechanical and viscoelastic properties of these composites were affected by the processing conditions. This was principally due to the modification of the initial aspect ratio of the natural fibers as a result of the shear stresses that developed in the mixer during the compounding. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1637–1642, 2003
On the relationship between modulus of elasticity and microhardness
Authors: Zamfirova Galina , Lorenzo Vicente , Benavente Rosario , Pereña José M.
Published: March 2003

The correlation between the modulus of elasticity, on the one side, and Vickers microhardness and total microhardness, on the other side, was analyzed in the case of ultrahigh molecular weight polyethylenes. An extension of the application of the power relation between microhardness and the modulus (MH = aEb) obtained by different methods was suggested. A linear dependence between constants obtained by Vickers and total microhardness measurements and other different techniques of modulus measurement was established, which signifies that both microhardness characteristics change their sensitivity toward the modulus in a similar way. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1794–1798, 2003
Direct observation of the main cell wall components of straw by atomic force microscopy
Authors: Yan Lifeng , Zhu Qingshi
Published: March 2003

Cellulose, hemicellulose, and lignin are the main cell wall components of straw. After removal of the wax and the major portion of lignin, the remaining components of the cell wall surface of straw were determined by atomic force microscopy, which revealed a network structure of cellulose and hemicellulose, and some lignin localized on the surface of the network, consistent with the cell wall model suggested by other researchers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2055–2059, 2003
Synthesis of a polyurethane–chitosan blended polymer and a compound process for shrink‐proof and antimicrobial woolen fabrics
Authors: Shih Chung‐Yang , Huang Kuo‐Shien
Published: March 2003

The purpose of this study was to develop a finishing process to improve the shrinkage and anti microbial properties of woolen fabrics. First, polyurethane (PU) prepolymers were synthesized from poly(ethylene glycol) (PEG) of different molecular weights. Next, the PU prepolymers were mixed with chitosan to form blended polymers. Then, these blended polymers were used to treat woolen fabric in a compound process to determine if they could modify the fabric, making it more resistant to shrinkage and bacteria. Our experimental results indicate an improvement in both the shrink‐proof and antimicrobial properties of the fabric with an increase in the temperature or duration of the heat treatment, as well as with an increase in the concentration of the processing agent. However, the yellowing and softness tendency of the fabric shifted towards the opposite, unfavorable direction. The treatment also seems to somewhat improve the strength of the fabric. Furthermore, our results show that the addition of chitosan remarkably increased the shrink‐proof and antimicrobial properties of the treated fabric. Finally, the blended polymer made of PEG with a molecular weight of 600 and chitosan gave the best results of the polymer combinations tested. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2356–2363, 2003
Effect of the temperature on the tensile mechanical behavior of irradiated linear polyethylene
Authors: Vallés E. M. , Failla M. D.
Published: March 2003

The mechanical behavior of two γ‐irradiated linear polyethylenes was determined at 75 and 105°C under tensile stress. Each polymer was crystallized from the melt after different thermal histories so that samples would be obtained with various degrees of crystallinity. Subsequently, they were irradiated in vacuo and at room temperature to total doses ranging from 20 to 200 kGy. The initial crystallinity, dose level, and test temperature determined whether the samples displayed ductile, brittle, or transitional behavior. The yield stress decreased as the temperature increased. The value of the yield stress at a given temperature showed a tendency to increase with dose; this became more evident as the initial crystallinity increased. The extensibility of ductile samples, estimated from the draw ratio after break, decreased with the gel content. For ductile samples, the temperature affected the values of this property when the gel fraction that developed in the samples was relatively low. The effect of temperature became less noticeable when the gel reached values larger than 60%. The ultimate stress, normalized with the crosslinking density, correlated with the draw ratio after break in a way that resembled the type of relationship observed in other crosslinked systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1925–1935, 2003
Emulsifier‐free emulsion copolymerization of styrene with methacrylic acid
Authors: Wang Ping‐Hua , Wang Qian‐Wen
Published: March 2003

The study on batch emulsifier‐free emulsion copolymerization of styrene with methacrylic acid was conducted. The copolymerization process was followed by gravimetry, infrared, and transmission electron microscopy. The copolymerization mechanism differs from that of styrene with acrylic acid. The effect of solid content on particle size was examined, and it was found that the particle size was increased as the solid content was increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1747–1751, 2003
Structure and electrical properties of grafted polypropylene/graphite nanocomposites prepared by solution intercalation
Authors: Shen Jing‐Wei , Chen Xiao‐Mei , Huang Wen‐Yi
Published: March 2003

A novel process was developed to prepare electrically conducting maleic anhydride grafted polypropylene (gPP)/expanded graphite (EG) nanocomposites by solution intercalation. The conducting percolation threshold at room temperature (Φc) of the nanocomposites was 0.67 vol %, much lower than that of the conventional conducting composites prepared by melt mixing (Φc = 2.96 vol %). When the EG content was 3.90 vol %, the electrical conductivity (σ) of the former reached 2.49 × 10−3 S/cm, whereas the σ of the latter was only 6.85 × 10−9 S/cm. The TEM, SEM, and optical microscopy observations confirmed that the significant decrease of Φc and the striking increase of σ might be attributable to the formation of an EG/gPP conducting multiple network in the nanocomposites, involving the network composed of particles with a large surface‐to‐volume ratio and several hundred micrometers in size, and the networks composed of the boards or sheets of graphite with high width‐to‐thickness ratio and particles of fine microscale or nanoscale sizes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1864–1869, 2003
Thermoplastic elastomeric blend of nitrile rubber and poly(styrene‐co‐acrylonitrile). I. Effect of mixing sequence and dynamic vulcanization on mechanical properties
Authors: Anandhan S. , De P. P. , De S. K. , Bhowmick Anil K.
Published: March 2003

The effects of dynamic vulcanization and blend ratios on mechanical properties and morphology of thermoplastic elastomeric (TPE) compositions, based on blends of nitrile rubber (NBR) and poly(styrene‐co‐acrylonitrile) (SAN), were studied. The TPE composition prepared by adding a rubber‐curatives masterbatch to softened SAN yields higher mechanical properties than that prepared by adding curatives to the softened plastic–rubber preblend. The blends having a higher rubber–plastic ratio (60 : 40 to 80 : 20) display thermoplastic elastomeric behavior, whereas those having a higher plastic–rubber ratio (50 : 50 to 90 : 10) display the behavior of impact‐resistant plastics. DSC studies revealed that NBR and SAN are thermodynamically immiscible. SEM studies of the thermoplastic elastomeric compositions show that SAN forms the matrix in which fine particles of NBR form the dispersed phase. It was further confirmed by dynamic mechanical thermal analysis. Dynamic vulcanization causes a decrease in the size of dispersed particles and improvement in mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1976–1987, 2003
Hybrid sol–gel membranes of polyacrylonitrile–tetraethoxysilane composites for gas permselectivity
Authors: Iwata Minoru , Adachi Takeharu , Tomidokoro Miwa , Ohta Michiyoshi , Kobayashi Takaomi
Published: March 2003

Sol–gel reaction of tetraethoxysilane (TEOS) with fumed silica–polyacrylonitrile (PAN) membrane was carried out to prepare hybrid gas permeable membranes for oxygen and nitrogen separation. Various amounts of fumed silica microparticles with a few μm diameters were compounded in PAN–dimethylsulfoxide (DMSO) solution. After casting of the viscous compound solution on a flat sheet with 100 μm thickness, DMSO was evacuated under vacuum at 80°C. Then, the silica–PAN composite membranes were treated with TEOS for 1 day at 40°C in methanol. Air permeation was examined and compared in silica–PAN composite membranes with and without TEOS treatment. The latter hybrid membranes showed selective oxygen permeability, which depended on amounts of fumed silica in the membrane. The TEOS hybrid PAN membranes have a high ability of oxygen permselectivity for O2/N2 gas mixture with α(O2/N2) = 13–17, when the silica content was in the range of 13–20 wt %. This is attributed to siloxane network formation in hybrid silica–PAN composite membranes. Favorable siloxane network formation resulted in high oxygen permeability of the hybrid composite membranes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1752–1759, 2003
Mechanical properties of high‐density polyethylene/scrap rubber powder composites modified with ethylene–propylene–diene terpolymer, dicumyl peroxide, and silicone oil
Authors: Li Yan , Zhang Yong , Zhang Yinxi
Published: March 2003

The effect of ethylene–propylene–diene terpolymer (EPDM), dicumyl peroxide (DCP), and dimethyl silicone oil on the mechanical properties of high‐density polyethylene (HDPE) composites filled with 60 mesh cryogenically scrap rubber powder (SRP) was studied. The addition of 10 wt % EPDM, 0.2 wt % DCP, and 4 wt % dimethyl silicone oil significantly increased both the impact strength and elongation at break of the HDPE/SRP composites. After the modification, the impact strength increased by 160%, and the elongation at break increased by 150% for the composites containing 40 wt % SRP. The impact load–time curves showed that the increase of impact energy for the modified composites was attributed to the increase of the maximum force at yield point and the ductile deformation after yielding. The rheological behavior, dynamic mechanical properties, and morphology observation suggested that an enhanced adhesion between SRP and polymer matrix formed in the modified HDPE/SRP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2020–2027, 2003
Precipitation polymerization of acrylic acid in compressed carbon dioxide–cosolvent systems
Authors: Xu Qun , Han Buxing , Yan Haike
Published: March 2003

Precipitation polymerizations of acrylic acid (AA) in compressed carbon dioxide (65 bar) with different cosolvents, acetic acid, ethanol, and tetrahydrofuran, were studied. Analyses by viscosity measurement and differential scanning calorimetry indicate that the cosolvents have a pronounced effect on the properties of the product. Scanning electron microscopy shows that the products progress from microparticles to bicontinuous networks to fibers with the change of cosolvents and reaction conditions. Measurement of the volume expansion (ΔV%) of the liquid phase containing different cosolvents indicates that the miscibility of compressed CO2 with the liquid phase is dependent on the cosolvent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1876–1880, 2003
Mechanical behavior of nylon composites containing talc and kaolin
Authors: Unal H. , Fındık F. , Mimaroglu A.
Published: March 2003

Particulate reinforced thermoplastic composites are designed to improve the properties and to lower the overall cost of engineering plastics. In this study, the influence of adding talc and kaolin fillers on the mechanical properties of nylon 6 was investigated. Fillers, either singly or mixed by various weight ratios between 10 and 30 wt %, were added to nylon 6. Test samples of the composite material were prepared by the injection‐molding process. Uniaxial tensile and Izod impact tests were carried out. Tensile strength, elongation at break, modulus of elasticity, and impact energy were obtained. The results showed that the tensile strength and modulus of elasticity of nylon 6 composite increased with the increase in filler ratio, whereas the impact strength and maximum elongation decreased with the increase in filler ratio. The optimal nylon composite was determined with the addition of a 10 to 15 wt % filler ratio. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1694–1697, 2003
Phase behavior of side‐chain liquid‐crystalline elastomers and their precursors containing para‐nitro azobenzene
Authors: Li Min , Hu Zhijun , Chen Gang , Chen Xinfang
Published: March 2003

Side‐chain liquid‐crystalline copolymethacrylates (PMm's), containing para‐nitro azobenzene as the mesogenic group and 2‐hydroxylethyl methacrylate (HEMA) as a comonomer, were synthesized by radical polymerization, and their corresponding liquid‐crystalline elastomers (LCEm's) were prepared through chemical crosslinking. All of the polymers (PMm's) and the elastomers studied showed enantiotropic smectic A phases; the clearing temperature (Ti) of the PMm polymers decreased with increasing amount of HEMA, and the Ti of the corresponding LCEm's decreased compared to that of their precursors. Small‐angle X‐ray scattering studies on the copolymers quenched from their liquid‐crystalline phases indicated that the characteristic distance increased with increasing amorphous component content and thus, the amorphous components were in between the smectic layers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2275–2279, 2003
Thermally induced phase separation in poly(lactic acid)/dialkyl phthalate systems
Authors: Lee Jae Sung , Lee Hwan Kwang , Kim Je Young , Hyon Suong‐Hyu , Kim Sung Chul
Published: March 2003

Thermally induced phase separation in poly(lactic acid)/dialkyl phthalate systems was investigated. Poly(DL‐lactic acid) (PDLLA) and poly(L‐lactic acid) (PLLA) with different molecular weights were used. A series of dialkyl phthalates, with different numbers of carbon atoms in the alkyl chain, were employed as solvents to control the interaction between polymer and solvent. The liquid–liquid phase‐separation temperature of the poly(lactic acid) solutions decreased systematically with a shorter alkyl chain in the phthalate. Based on the interaction between polymer and solvent and the molecular weight of polymer influencing liquid–liquid phase‐separation temperature significantly but crystallization temperature only slightly, proper thermal conditions were employed to investigate competitive phase separation and crystallization in PLLA solutions. Factors that can influence the final morphology of PLLA solutions were examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2224–2232, 2003
A nanocomposite of poly(N‐vinylcarbazole) with nanodimensional alumina
Authors: Maity Arjun , Biswas Mukul
Published: March 2003

A nanocomposite of poly(N‐vinylcarbazole) (PNVC) and Al2O3 was prepared by precipitation of a preformed PNVC in a tetrahydrofuran solution onto an aqueous suspension of nanodimensional Al2O3. Prolonged extraction of a PNVC–Al2O3 composite by benzene failed to extract the loaded PNVC from the Al2O3, as shown by Fourier transform infrared studies. Scanning electron microscopy analyses revealed distinct morphological features of the composite, and transmission electron microscopy analyses confirmed that the particle sizes were in the range of 120–240 nm. Thermogravimetric analyses demonstrated the enhanced stability of the nanocomposite relative to the base polymer. Direct current conductivity of the PNVC–Al2O3 composites was found to be about 0.14 × 10−6 S/cm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2233–2237, 2003
Toughness response of vinylester/epoxy‐based thermosets of interpenetrating network structure as a function of the epoxy resin formulation: Effects of the cyclohexylene linkage
Authors: Karger‐Kocsis J. , Gryshchuk O. , Jost N.
Published: March 2003

Vinylester/epoxy (VE/EP)‐based thermosets of interpenetrating network (IPN) structures were produced by using a VE resin (bismethacryloxy derivative of a bisphenol A–type EP resin) with aliphatic (Al‐EP) and cycloaliphatic (Cal‐EP) EP resins. Curing of the EP resins occurred either with an aliphatic (Al‐Am) or cycloaliphatic diamine compound (Cal‐Am). Dynamic mechanical thermal analysis (DMTA) and atomic force microscopy (AFM) suggested the presence of an interpenetrating network (IPN) in the resulting thermosets. Fracture toughness (Kc) and fracture energy (Gc) were used as the toughness characterization parameters of the linear elastic fracture mechanics. Unexpectedly high Kc and Gc data were found for the systems containing cyclohexylene units in the EP network, such as VE/Al‐EP+Cal‐Am and VE/Cal‐EP+Al‐Am. This was attributed to the beneficial effects of the conformational changes of the cyclohexylene linkages (chair/boat), which were closely analogous to those in some thermoplastic copolyesters. The failure mode of the VE/EP thermoset combinations was studied in scanning electron microscopy (SEM) and discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2124–2131, 2003
Characterization of unsaturated polyester and alkyd resins using one‐ and two‐dimensional NMR spectroscopy
Authors: Spyros A.
Published: March 2003

One‐ (1D) and two‐dimensional (2D) 1H‐ and 13C‐NMR spectroscopy was used to characterize polyester and alkyd resins used in the coatings industry. The wealth of chemical composition information of the 1H‐ and 13C‐NMR 1D spectra of the resins is revealed through 2D NMR experiments that spread chemical shifts in two dimensions, thus facilitating the peak assignment of the various components of the resins. It is shown that the types of polyols, acids, and vegetable oils used to modify the resins can be efficiently traced by NMR spectroscopic techniques. Information on the quantitative composition of the resins and especially the abundance of unsaturated fatty acid double bonds, which influences resin dryability and hardness, can be easily extracted from the 1H‐NMR spectra upon successful assignment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1881–1888, 2003
Static and dynamic mechanical properties of modified bismaleimide and cyanate ester interpenetrating polymer networks
Authors: Fan Jing , Hu Xiao , Yue Chee Yoon
Published: March 2003

Interpenetrating polymer networks (IPNs) based on different ratios of modified bismaleimide (BMI) resin [BMI/2,2′‐diallylbisphenol A (DBA)] and cyanate ester (CE) (b10) have been synthesized via prepolymerization followed by thermal curing. A systematic study of both static and dynamic mechanical properties of the cured BMI/DBA–CE IPN resin systems was conducted through flexural, impact testing, and dynamic mechanical analysis (DMA). The static mechanical investigation shows that the flexural strength, flexural strain at break, and impact strength of the cured BMI/DBA–CE IPN resin systems are relatively lower than that calculated by rule of mixture of two individuals: BMI/DBA and b10. However, the flexural moduli of the IPN resin systems have more consistent features compared to that calculated by rule of mixture. Single damping peaks are detected for the cured BMI/DBA–CE IPN resin systems, which suggests a substantial degree of interpenetration between two networks. The damping peaks of the cured BMI/DBA–CE IPN resin systems do tend to become broader with increasing concentration of BMI/DBA, whereas the intensity of damping peaks of the IPN resin systems decreases. The obtained results not only provide insight information about the characteristic structures of these BMI/DBA‐–CE IPN resin systems, but also give guidelines for their applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2000–2006, 2003
Remyelination by transplanted olfactory ensheathing cells
Authors: Franklin Robin J.M.
Published: March 2003

The olfactory ensheathing cells (OECs) of the peripheral olfactory system associate with the axons of the first cranial nerve. These axons are not myelinated by OECs because of their very small diameter. However, when OECs are transplanted into areas where they encounter larger‐diameter axons, such as in a model of primary demyelination, these cells assume a myelinating phenotype. Myelinating OECs very closely resemble myelinating Schwann cells by all criteria currently examined, including morphology, ultrastructure, biochemistry, and transcriptional regulation. Indeed, it is currently impossible to reliably distinguish myelinating OECs and myelinating Schwann cells that have been transplanted into experimental models of CNS demyelination. This article describes recent studies on the myelinating properties of transplanted OECs, focusing on their intrinsic myelinating potential and how this can be augmented by the presence of meningeal cells. The relative merits of OECs compared with Schwann cells when transplanted into astrocyte‐containing lesions in the CNS are discussed together with their potential role in transplanted‐mediated repair of demyelinating disease such as multiple sclerosis. Anat Rec (Part B: New Anat) 271BB:71–76, 2003. © 2003 Wiley‐Liss, Inc.