bluuebunny/crossref_metadata_2025 huggingface dataset:
Familial dysautonomia: Detection of the IKBKAP IVS20+6T → C and R696P mutations and frequencies among Ashkenazi Jews
Authors: Dong Jianli , Edelmann Lisa , Bajwa Asghar M. , Kornreich Ruth , Desnick Robert J.
Published: October 2002

Familial dysautonomia (FD) is an autosomal recessive congenital neuropathy that occurs almost exclusively in the Ashkenazi Jewish (AJ) population. Mutations in the IκB kinase complex‐associated protein (IKBKAP) gene cause FD. Two IKBKAP mutations, IVS20+6T → C and R696P, have been identified in FD patients of AJ descent. The splice site mutation IVS20+6T → C is responsible for > 99.5% of known AJ patients with FD, and haplotype analyses were consistent with a common founder. In contrast, the R696P mutation has been identified in only a few AJ patients. To facilitate carrier detection, a single PCR and allele‐specific oligonucleotide (ASO) hybridization assay was developed to facilitate the detection of both the IVS20+6T → C and R696P mutations. Screening of 2,518 anonymous AJ individuals from the New York metropolitan area revealed a carrier frequency for IVS20+6T → C of 1 in 32 (3.2%; 95% CI, 2.5–3.9%), similar to the previously estimated carrier frequency (3.3%) based on disease incidence. No carrier was identified for the R696P lesion, indicating that the mutation was rare in this population (< 1 in 2,500). This sensitive and specific assay should facilitate carrier screening for FD mutations in the AJ community, as well as postnatal diagnostic testing. © 2002 Wiley‐Liss, Inc.
Mosaic variegated aneuploidy with growth hormone deficiency and congenital heart defects
Authors: Lane Andrew H. , Aijaz Naghma , Galvin‐Parton Patricia , Lanman Joseph , Mangano Robert , Wilson Thomas A.
Published: October 2002

We describe a 12‐year‐old boy with mosaic variegated aneuploidy (MVA), subnormal response to growth hormone (GH) stimulation testing, and short stature. In addition to features more commonly described in MVA such as microcephaly, cognitive deficits, and certain facial features, he also has features not commonly reported in MVA, including short limb segments, epidermoid cysts, ventricular septal defect, and subaortic stenosis. Chromosomal analysis revealed hyperdiploid chromosome numbers ranging from 47 to 70; modal number 50, in 24% of the metaphases. This case demonstrates that although the phenotype of MVA almost always includes growth failure, microcephaly, and mental retardation, additional features may vary greatly across individuals. His clinical features and course suggest that in addition to GH deficiency, he may have an intrinsic inability of the growth plate to respond to growth hormone. © 2002 Wiley‐Liss, Inc.
Genetic heterogeneity of syndromic X‐linked recessive microphthalmia‐anophthalmia: Is Lenz microphthalmia a single disorder?
Authors: Ng David , Hadley Donald W. , Tifft Cynthia J. , Biesecker Leslie G.
Published: October 2002

Nonsyndromic congenital microphthalmia or anophthalmia is a heterogeneous malformation with autosomal dominant, autosomal recessive, and X‐linked modes of inheritance. Lenz microphthalmia syndrome comprises microphthalmia with mental retardation, malformed ears, skeletal anomalies, and is inherited in an X‐linked recessive pattern. Prior studies have shown linkage of both isolated (or nonsyndromic) anophthalmos (ANOP1, [MIM 301590]) and Lenz syndrome [MIM 309800] to Xq27–q28. Nonsyndromic colobomatous microphthalmia [MIM 300345] has been linked to Xp11.4–Xq11.1. We describe a five‐generation African‐American family with microphthalmia or anophthalmia, mental retardation, and urogenital anomalies, in an X‐linked recessive inheritance pattern, consistent with Lenz syndrome. Initial linkage analysis with microsatellite markers excluded the region in Xq27–q28 previously reported as a candidate region for ANOP1 [MIM 301590]. An X‐chromosome scan revealed linkage to a 10‐cM region between markers DXS228 and DXS992 in Xp11.4–p21.2. Multipoint analysis gave a maximum LOD score of 2.46 at marker DXS993. These data show that X‐linked recessive syndromic microphthalmia exhibits genetic heterogeneity. In addition, it suggests that Lenz microphthalmia syndrome, previously thought to be a single disorder, may represent an amalgam of two distinct disorders. © 2002 Wiley‐Liss, Inc.
Frameshift mutation in the cartilage‐derived morphogenetic protein 1 (CDMP1) gene and severe acromesomelic chondrodysplasia resembling Grebe‐type chondrodysplasia
Authors: Faiyaz‐Ul‐Haque Muhammad , Ahmad Wasim , Wahab Abdul , Haque Sayedul , Azim Anser C. , Zaidi Syed H.E. , Teebi Ahmad S. , Ahmad Mahmud , Cohn Daniel H. , Siddique Teepu , Tsui Lap‐Chee
Published: October 2002

Grebe‐type chondrodysplasia exhibits a severe form of limb shortening and appendicular bone dysmorphogenesis. Here we report a family with seven males and six females who inherited the disorder in an autosomal recessive fashion. While the carrier parents did not exhibit any apparent skeletal abnormalities, all affected patients had a similar phenotype with unaffected axial and craniofacial bones. Since mutations in the cartilage‐derived morphogenetic protein 1 (CDMP1) gene have been reported in similar acromesomelic chondrodysplasias, we examined genomic DNA from affected and normal subjects for possible mutations in CDMP1. In affected subjects, an insertion of a C at nucleotide 297 of the coding sequence was discovered. This insertion produced a shift in the reading frame at amino acid residue 99, causing premature termination of the polypeptide six amino acids downstream. DNA samples from 41 control subjects did not show this mutation. The truncated CDMP1 protein in these subjects is predicted to cause a total loss of its signaling function. The present report confirms that CDMP1 plays an important role in the regulation of axial bone growth during development and suggests that its absence does not impair other developmental processes.© 2002 Wiley‐Liss, Inc.
Genome‐wide linkage analysis for celiac disease in North American families
Authors: Neuhausen Susan L. , Feolo Mike , Camp Nicola J. , Farnham James , Book Linda , Zone John J.
Published: October 2002

Celiac disease (CD) is an autoimmune disease caused by sensitivity to the dietary protein gluten. It has a prevalence of 1 in 250 in the United States. Multiple‐case families are common with a risk to siblings from 10–12%. Previous linkage studies have found no significant evidence for linkage other than to HLA. In this study, we performed a genome‐wide search on 62 families with at least two cases of CD to identify non‐HLA loci for CD. Two‐point and multipoint parametric and nonparametric analyses were performed on the entire set of families and on sets stratified by the HLA genotype. Accounting for multiple testing, we found genome‐wide intermediate linkage evidence at 18q (heterogeneity LOD (HLOD) = 3.6) and at 3p (HLOD = 3.2) and suggestive evidence at 5p (HLOD = 2.7). Good consensus between two‐point and multipoint evidence was not found, and after genotyping with new markers in these regions, our results were inconclusive. The 18q region had intermediate two‐point evidence, but weak multipoint evidence. At 3p and 5p, the addition of follow‐up markers added flanking support, yet multipoint evidence was still lacking. Our results indicate that multipoint analyses may be hindered by the complexity of CD. Multipoint analyses are not robust to model misspecification, and further development of models is needed. Additional study of these and other families is necessary to validate or rule out the regions implicated in this study. © 2002 Wiley‐Liss, Inc.
Epidemiology and treatment of mitochondrial disorders
Authors: Chinnery Patrick F. , Turnbull Douglass M.
Published: October 2002

The last ten years have seen a huge increase in the number of different genetic defects found in patients with mitochondrial disorders, but the true impact of mitochondrial disease is only just becoming apparent. Mitochondrial diseases are far more common than was anticipated. Although there have also been major advances in our understanding of mitochondrial pathology, the clinical management of patients with mitochondrial disease is largely supportive. In this article, we focus on primary disorders of the mitochondrial respiratory chain and mtDNA defects. We review the available epidemiological data, outline current strategies for the management of mitochondrial disease, and highlight new therapeutic approaches that may prove useful in the future. © 2001 Wiley‐Liss, Inc.
Epilepsy and genetic malformations of the cerebral cortex
Authors: Guerrini Renzo , Carrozzo Romeo
Published: October 2002

Malformations of the cerebral cortex are an important cause of developmental disabilities and epilepsy. Here we review those malformations for which a genetic basis has been elucidated or is suspected and the types of associated epilepsy. Schizencephaly (cleft brain) has a wide anatomo‐clinical spectrum, including partial epilepsy in most patients. Familial occurrence is rare. Heterozygous mutations in the EMX2 gene were reported in 13 patients. X‐linked bilateral periventricular nodular heterotopia (BPNH) consists of typical BPNH with epilepsy in females and prenatal lethality in males. About 88% of patients have partial epilepsy. Filamin A mutations, all leading to a truncated protein, have been reported in three families and in sporadic patients. The most frequent forms of lissencephaly (agyria‐pachygyria) are caused by mutations of LIS1. XLIS mutations cause classical lissencephaly in hemizygous males and subcortical band heterotopia (SBH) in heterozygous females. The thickness of the heterotopic band and the degree of pachygyria correlate with the likelihood of developing Lennox‐Gastaut syndrome. Mutations of the coding region of XLIS were found in all reported pedigrees and in 38–91% of sporadic female patients with SBH. With few exceptions, children with LIS1 mutations have isolated lissencephaly, with severe developmental delay and infantile spasms. Autosomal recessive lissencephaly with cerebellar hypoplasia, accompanied by severe developmental delay, seizures, and hypotonia has been associated with mutations of the reelin gene. Fukuyama congenital muscular dystrophy is due to mutations of the fukutin gene and is accompanied by polymicrogyria. Febrile seizures and epilepsy with generalized tonic‐convulsions appear in about 50% of children but are usually not severe. Tuberous sclerosis (TS) is caused by mutations in at least two genes, TSC1 and TSC2; 75% of cases are sporadic; 60% of patients have epilepsy, manifested in 50% of them as infantile spasms. TSC1 mutations seem to cause a milder disease with fewer cortical tubers and lower frequency of seizures. Among several syndromes featuring polymicrogyria, bilateral perisylvian polymicrogyria had familial occurrence on several occasions. Genetic heterogeneity is likely, including autosomal recessive, X‐linked dominant, X‐linked recessive inheritance, and association with 22q11.2 deletions. About 65% of patients have severe epilepsy, often Lennox‐Gastaut syndrome. © 2001 Wiley‐Liss, Inc.
Longitudinal analysis of length growth in the chimpanzee (Pan troglodytes)
Authors: Hamada Yuzuru , Udono Toshifumi
Published: October 2002

The adolescent growth spurt in linear dimension in humans is considered to be unique among mammals, but few comparative studies have been done, even on chimpanzees. Growth of the summed length of crown to rump, thigh, and leg was studied longitudinally in 12 chimpanzees. We took body weight growth and reproductive maturation into consideration. Reproductive maturation was monitored by the swelling of sexual skin and menarche in females, and by testicular development in males. We applied two relationships found in humans between body length growth and the environment to the chimpanzees. The first relationship was the robustness of the growth spurt, meaning that the spurt is absent only in individuals under the most severe environmental pressure. Subjects maturing in a favorable or even mediocre environment are anticipated to show the growth spurt. The second relationship was catch‐up growth, where, when the environment is ameliorated, growth may be accelerated to attain the target size. Catch‐up growth at the end of the juvenile period may mimic the adolescent growth spurt. Results showed that subjects living under favorable conditions did not exhibit a growth spurt, and that it was only the subjects who had delayed growth in the juvenile period that showed a spurt in adolescence, the period when reproductive maturation occurred. Although we have concluded that chimpanzees do not have an adolescent growth spurt, except in cases of catch‐up growth, this does not mean that they have a different growth pattern from that of humans. The absence of a growth spurt may be associated with adaptations to chimpanzee patrilineal society, where adolescent males are incorporated into the adult hierarchy at a low rank. Am J Phys Anthropol 118:268–284, 2002. © 2002 Wiley‐Liss, Inc.
Cross‐site differences in foraging behavior of white‐faced capuchins (Cebus capucinus)
Authors: Panger Melissa A. , Perry Susan , Rose Lisa , Gros‐Louis Julie , Vogel Erin , Mackinnon Katherine C. , Baker Mary
Published: October 2002

Researchers have identified a variety of cross‐site differences in the foraging behavior of free‐ranging great apes, most notably among chimpanzees (Pan troglodytes) and more recently orangutans (Pongo pygmaeus), that are not due to obvious genetic or ecological differences. These differences are often referred to as “traditions.” What is not known is whether this high level of interpopulation variation in behavior is limited to hominoids. In this study, we use long‐term data from three Costa Rican field sites that are geographically close and similar ecologically to identify potential foraging traditions in white‐faced capuchins (Cebus capucinus). Foraging traditions are predicted in Cebus because of many behavioral and morphological convergences between this genus and the great apes. The processing techniques used for the same food species were compared across sites, and all differences found were classified as present, habitual, or customary. Proximity data were also analyzed to determine if social learning mechanisms could explain variation in foraging behavior. Of the 61 foods compared, we found that 20 of them are processed differently by capuchins across sites. The differences involve pound, rub, tap, “fulcrum,” “leaf‐wrap,” and “army ant following.” For most of the differences with enough data to analyze, the average proximity score of the “matched” dyads (two individuals within a group who shared a “different” processing technique) was statistically higher than the average proximity score of the remaining “unmatched” dyads. Am J Phys Anthropol 119:52–66, 2002. © 2002 Wiley‐Liss, Inc.
X‐linked creatine deficiency syndrome: A novel mutation in creatine transporter gene SLC6A8
Authors: Bizzi Alberto , Bugiani Marianna , Salomons Gajja S. , Hunneman Donald H. , Moroni Isabella , Estienne Margherita , Danesi Ugo , Jakobs Cornelis , Uziel Graziella
Published: October 2002

Among creatine deficiency syndromes, an X‐linked condition related to a defective creatine transport into the central nervous system has been described recently. Hallmarks of the disease are the absence of a creatine signal at brain spectroscopy, increased creatine levels in blood and urine, ineffectiveness of oral supplementation, and a mutation in the SLC6A8 (Online Mendelian Inheritance in Man [OMIM] 300036) creatine transporter gene. We report on a patient in whom a novel mutation (1221‐1223delTTC) was identified.
Preparation of core–shell type nanoparticles of diblock copolymers of poly(L‐lactide)/poly(ethylene glycol) and their characterization in vitro
Authors: Yu Jeong‐Jun , Jeong Young‐Il , Shim Yong‐Ho , Lim Gyun‐Taek
Published: October 2002

Core–shell type nanoparticles of poly(L‐lactide)/poly(ethylene glycol) (LE) diblock copolymer were prepared by a dialysis technique. Their size was confirmed as 40–70 nm using photon correlation spectroscopy. The 1H‐NMR analysis confirmed the formation of core–shell type nanoparticles and drug loading. The particle size, drug loading, and drug release rate of the LE nanoparticles were slightly changed by the initial solvents that were used. The drug release behavior of LE core–shell type nanoparticles showed an initial burst during the first 12 h and then a sustained release until 100 h. The degradation behavior of LE block copolymer nanoparticles was divided into three phases: the initial rapid degradation phase, the stationary phase, and the rapid degradation phase until complete degradation. It was suggested that lidocaine release kinetics were predominantly governed by the diffusion mechanism in the initial burst phase and after that by both of the diffusion and degradation mechanisms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2625–2634, 2002
Hot‐wire parallel technique: A new method for simultaneous determination of thermal properties of polymers
Authors: Santos Wilson Nunes Dos , Gregorio Rinaldo
Published: October 2002

The hot‐wire parallel technique standardized for determining the thermal conductivity of ceramic materials was employed in the determination of the thermal properties of polymers. For these materials, additional care must be taken considering the low melting point of polymers, when compared with that for ceramic materials. Samples can be prepared either in the shape of bricks or in the shape of half‐cylinders. The thermal conductivity and the specific heat were simultaneously determined from the same experimental thermal transient, and the thermal diffusivity is derived from these properties. Five different polymers with different structures at room temperature were selected, and measurements were carried out from room temperature to approximately the maximum service operating temperature. A nonlinear least‐squares fitting method was employed in the calculations, so that all the experimental points obtained are considered in the thermal properties' calculations. The apparatus used in this work is fully automatic. The reproducibility is very good with respect to the thermal conductivity, even with a defective experimental arrangement with respect to the theoretical model. However, deviations from the theoretical model have a severe influence on the specific heat values and, consequently, on the thermal diffusivity. Experimental results were compared with those available in the literature, showing the applicability of this technique for the determination of thermal properties of polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1779–1786, 2002
Thermal crosslinking of collagen immobilized on poly(acrylic acid) grafted poly(ethylene terephthalate) films
Authors: Gupta Bhuvanesh , Hilborn Jöns , Plummer Christopher , Bisson Isabelle , Frey Peter
Published: October 2002

Graft polymerization of acrylic acid onto plasma‐treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for collagen immobilization by dip‐coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma‐treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after collagen immobilization the contact angle remained relatively stable. The amount of collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the collagen in the range 110–130 °C. Atomic force microscopy (AFM) observations suggested that the washed crosslinked collagen has a very similar structure to that of the un‐crosslinked collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1874–1880, 2002
Detection and determination of CrVI in solution using polyaniline modified quartz crystal electrode
Authors: Mirmohseni Abdolreza , Oladegaragoze Ali
Published: October 2002

Conducting polymers such as polyaniline and polypyrrole exhibit novel sensoric properties and are able to interact chemically or electrochemically with the species of interest for detection. In the current investigation, construction of a sensor based on an electrochemical reaction between CrVI and a thin layer of polyaniline, coated at the surface of quartz crystal electrode, is reported. Polyaniline was synthesized, electrochemically, at the surface of quartz crystal electrode. It was then reduced at −0.1 V versus Ag/AgCl. The modified electrode was exposed to various concentrations of CrVI solutions ranging from 10−7 to 10−1M. Mass changes of the polymer‐modified electrode due to the reaction between CrVI and polyaniline was found to be linear, corresponding to the concentration of CrVI. The experiments in both acidic and nonacidic conditions were performed. In both conditions, linear double‐loga
thmic calibration curves of mass change of the polymer film versus CrVI concentration were obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2772–2780, 2002
The effect of morphology of ternary‐phase polypropylene/glass bead/ethylene‐propylene rubber composites on the toughness and brittle‐ductile transition
Authors: Dubnikova I. L. , Berezina S. M. , Antonov A. V.
Published: October 2002

Correlation between the morphology and the impact toughness was studied for ternary‐phase polypropylene (PP)/glass bead (GB)/ethylene‐propylene rubber (EPR) composites containing 5–40 vol % of rigid filler at a fixed volume fraction ratio EPR/GB equal to 0.33. The three following types of phase morphology were obtained: (1) separate dispersion of phases and weak GB–PP adhesion; (2) separate dispersion of phases and high GB–PP adhesion; and (3) encapsulation of GB particles by elastomer shell. Maleated PP or EPR was used for the preparation of second and third types of composites, respectively. Binary composites with either rigid or rubbery phases were prepared as model systems. Young's modulus values of composites containing GB encapsulated by a soft interlayer stay close to neat PP modulus and are located in the bounds corresponding to ternary systems with phase‐separate distribution and rubber‐modified PP. Notched impact strength was measured by Izod and three‐point bending tests. Systems with the phase‐separate distribution both with weak and with high adhesion exhibit quasi‐brittle fracture. The encapsulation of GB particles by elastomer results in significant improvement of the toughness. An increase in core‐shell inclusion fraction leads to intense matrix yielding within a specimen bulk and brittle–ductile transition similar to the rubber‐toughened PP. A criterion of brittle–ductile transition was proposed on the basis of load‐time curve analysis, which is an accumulation of critical plastic deformation on a crack initiation stage. The stress of start of local failure microprocesses at the inclusion–matrix boundary was found to play the dominating role in energy‐dissipating mechanisms. The lowering of the stress at which a local matrix yielding starts at elastomer shell–PP interface compared to the stress of GB debonding is a main source of intensive energy adsorption at the initiation stage in the system with encapsulated GB. The optimal stiffness–toughness balance can be obtained by coating the rigid particles with an elastomer shell. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1911–1928, 2002
Preparation and characterization of syndiotactic polystyrene/ethylene‐propylene copolymer blends
Authors: Choi Won‐Mook , Park Cheon‐Il , Park O Ok , Lim Jae‐Gon
Published: October 2002

The reactive compatibilization of syndiotactic polystyrene (sPS)/oxazoline‐styrene copolymer (RPS)/maleic anhydride grafted ethylene‐propylene copolymer (EPR‐MA) blends is investigated in this study. First, the miscibility of sPS/RPS blends is examined by thermal analysis. The cold crystallization peak (Tcc) moved toward higher temperature with increased PRS, and, concerning enthalpy relaxation behaviors, only a single enthalpy relation peak was found in all aged samples. These results indicate that the sPS/RPS blend is miscible along the various compositions and RPS can be used in the reactive compatibilization of sPS/RPS/EPR‐MA blends. The reactive compatibilized sPS/RPS/EPR‐MA blends showed finer morphology than sPS/EPR‐MA physical blends and higher storage modulus (G') and complex viscosity (η*) when RPS contents were increased. Moreover, the impact strength of sPS/RPS/EPR‐MA increased significantly compared to sPS/EPR‐MA blend, and SEM micrographs after impact testing show that the sPS/RPS/EPR‐MA blend has better adhesion between the sPS matrix and the dispersed EPR‐MA phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2084–2091, 2002
Research of a membrane's material by reversed gas chromatography
Authors: Romaniuk O. I. , Turovskiy A. A. , Kurechko N. I. , Prystansky R. E. , Zaikov G. E. , Zaikov V. G.
Published: October 2002

Research of a membrane's polymeric material obtained by photoinitiated radical polymerization of oligocarbonate methacrylate and butyl methacrylate (BMA) was conducted by the method of reversed gas chromatography. The presence of defects of two types in the polymer was confirmed: as gaps between grains, and spongy interlayers. It has been established, that the relative size of gaps between grains more than in 1.5 times exceeds the size of interlayers between grains. The selective separation of substances proceeds through interlayers between grains. The size of interlayers (polymer's Tg) depends on structure of an initial composition. Increase of the BMA contents in an initial composition leads to polymer's Tg increase, condensation of interlayers between grains, and increase of selectivity of the appropriate membrane. This dependence has an extremal character. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2725–2728, 2002
Molecular structure and hydrophobicity of polymeric fluorocarbon films deposited on PET substrates
Authors: Qi H. J. , Wang D. , Ma Z. L. , Sun S. Q. , Sui Q. Y. , Zhang W. P. , Lu J. J.
Published: October 2002

Sputter‐coated polymeric fluorocarbon films (PFCF) on poly(ethylene terephthalate) (PET) are prepared under conditions of various power and pressure levels. By analysis of X‐ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR), low fluorine‐to‐carbon (F/C) ratios, 1.02–0.61, indicate that the deposited films are highly crosslinked‐unsaturated and the F/C ratio is found to be remarkably influenced by the power and slightly affected by the pressure due to the change in various structure components in the film molecules. The nonwettable properties of the PFCF are consistent with the results obtained by XPS‐IR analysis. The cleavage of the sharp peak assigned to CO stretch in the FTIR spectra of the PFCF‐PET film can be thought to be an evidence related to the newly formed FC bond on a certain site of ester group next to benzene ring in PET macromolecules. Therefore, the chemical bond at the interface between FCPF and PET can be expected to enhance the joint strength of the interface. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1843–1850, 2002
Synthesis and properties of photochromic cholesteric liquid crystalline polysiloxane containing chiral mesogens and azobenzene photochromic groups
Authors: Zhi Junge , Zhang Baoyan , Zang Baoling , Shi Guohua
Published: October 2002

A series of novel thermotropic side‐chain liquid crystalline polymers(P0–P12) were synthesized by grafting copolymerization of mesogenic monomer cholesteryl undecylenate (M1) and photochromic monomer 4‐allyoxy‐4′‐nitroazobenzene (M2) on polymethylhydrosiloxane. The chemical structures of polymers were characterized by infrared (IR) and ultraviolet (UV) spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to measure the thermal properties of those polymers, and the mesogenic properties were characterized by polarized optical micrograph, DSC, wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The glass transition temperatures (Tgs) of the polymers increased from P0 to P4 and decreased from P5 to P12. The clearing point temperatures (Tis) of the polymers P1–P12 were lower than that of P0, but increased from P1 to P4 and decreased from P5 to P12. They showed thermotropic liquid crystalline properties in a broad mesogenic region at temperatures >100°C. The polymers P0–P8 exhibited a cholesteric mesophase with oily streaks and lined texture, and polymers P9–P12 showed a chiral smectic mesogenic phase with a layered texture. All of the polymers were thermally stable to ∼ 320°C. The UV‐induced trans–cis photoisomerization was investigated for the azo monomer and polymers P8 and P12. The solution of the azo monomer and liquid crystalline polymers P8 and P12 can undergo photoisomerization, and the environments of the azo group were responsible for the aforementioned photochemical process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2155–2162, 2002
Activity of a β‐nucleating agent for isotactic polypropylene and its influence on polymorphic transitions
Authors: Marco C. , Gómez M. A. , Ellis G. , Arribas J. M.
Published: October 2002

The influence of a nonpigmenting β‐nucleating additive in the crystallization of isotactic polypropylene (iPP) is investigated by differential scanning calorimetry and X‐ray diffraction. It is found that this additive induces the formation of a very high level of the trigonal modification of iPP. The crystallization and melting behavior of the nucleated systems are studied as a function of the cooling and heating rates and the control of the final temperature during the cooling process. The nucleating agent exerts an important effect on the crystallization temperatures and the polymorphic transitions of iPP, delaying the β–α recrystallization process through an increase in the stability of the trigonal crystals. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 531–539, 2002
Mechanical and dynamic mechanical properties of jute fibers–Novolac–epoxy composite laminates
Authors: Datta Chandan , Basu Diya , Banerjee Amarnath
Published: October 2002

A study was done of jute composite using a polymer matrix of epoxidized Novolac resin (ENR), diglycidyl ether of bisphenol A (DGEBA)–based epoxy, and their blends with different weight percentages of the resins. It was found that on blending ENR with DGEBA, the storage modulii at room temperature are enhanced by about 100% or more in the case of 30 and 40% ENR‐containing matrices, whereas the enhancement in the case of 20 and 12% ENR‐containing matrices is only 50% that of the pure matrix. It was also observed that the tan δ peak heights of the composites containing 30 and 40% ENR are closer to that of 20% ENR‐containing composite. The probable explanation drawn on the basis of experimental findings of DMA and mechanical analysis is that by blending ENR with DGEBA epoxy it is possible to manufacture jute composites with increased stiffness without sacrificing their ductility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2800–2807, 2002
Flow‐injection polymer analysis of styrenic block copolymers. II
Authors: Poché Drew S. , Esneault Calvin P. , Roetker Susan L. , Heitman Tim E.
Published: October 2002

A flow‐injection polymer analysis (FIPA) method for the dilute solution characterization of unsaturated styrenic block copolymers was developed. The method is rapid, works with both butadiene and isoprene comonomers, and covers a range of 0–100% styrene content in the polymer. Solutions of the polymer were introduced into a flowing mobile phase and monitored by an array of three close‐coupled detectors: a right‐angle laser light‐scattering unit, a differential refractive index detector (DRI), and a differential pressure viscometer. In addition, a separate, dual‐detector instrument was set up specifically to evaluate the styrene content by the FIPA method. In that case, the detectors were a DRI and an ultraviolet detector. Within an analysis time of a few minutes, information on molecular weight, molecular size, and comonomer composition could be obtained directly. The data were compared to those obtained from a preexisting gel permeation chromatography analysis method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2190–2201, 2002
Photochemically induced birefringence in polyurethanes containing donor‐acceptor azobenzenes as photoresponsive moieties
Authors: Hasegawa Makoto , Ikawa Taiji , Tsuchimori Masaaki , Watanabe Osamu
Published: October 2002

Three kinds of photoresponsive polyurethanes containing slightly different azobenzene moieties [i.e., disperse red 19 (DR19), 2‐position‐substituted DR19, and 2,2′‐position‐substituted DR19] were prepared, and their photoinduced birefringence behavior was examined. These polyurethanes showed nearly the same molecular weights, glass transition temperatures, viscosities, and absorption coefficients at the wavelength of the light used to induce the photoresponse. Irradiation of these polymer films with a linearly polarized Ar+ laser induced birefringence due to reorientation of the azobenzene moieties through multiple trans‐cis‐trans isomerization cycles. Despite the slight difference in the chemical structure of the azobenzene moiety, a large difference in the growth behavior of the photoinduced birefringence was observed among these polymers. Because of the small differences in the characteristics of these polymers, we concluded that the isomerization behavior of the azobenzene moiety was the main factor for the results obtained in this study. In addition, the saturated value of the induced birefringence differed to a great extent among these polymers. It was suggested that such a phenomenon could be related to the reorientation behavior induced by the introduction of two methyl groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 17–22, 2002
Dielectric and mechanical properties of polystyrene/acrylonitrile–butadiene rubber blends
Authors: Abd‐El‐Messieh S. L. , Eid M. A. M. , Hussein A. I.
Published: October 2002

The dielectric and mechanical properties of polystyrene(PS)/acrylonitrile–butadiene rubber (NBR) blends were studied with the aim of improving the insulation properties of NBR. Compatibility investigations, performed with viscosity and dielectric methods and confirmed with the calculated heat of mixing, indicated that such blends were incompatible. To overcome the problem of phase separation between NBR and PS, we chose epoxidized soya bean oil to act as a compatibilizer and added 3% to the blends under investigation. This led to the conclusion that a sample containing 10% PS (either pure or scrap) possessed the most suitable electrical and mechanical properties. For this reason, the sample was chosen for studying the effect of the addition of three types of fillers (quartz, talc, and calcium carbonate) in increasing quantities (up to 80 phr) on the dielectric and mechanical properties. The variation of the dielectric properties with temperature (20–60°C) was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 540–552, 2002
Studies on some acrylamido polymers and copolymer as stabilizers for nitrocellulose
Authors: Hassan M. A. , Shehata A. B.
Published: October 2002

para‐Phenylene diamine was reacted with diethylmalonate and the product was reacted with acryloyl chloride to obtain the corresponding acrylamido malonanilide monomer. para‐Nitro aniline was also reacted with acryloyl chloride to obtain the corresponding monomer. The two monomers were homopolymerized and then copolymerized. The obtained homopolymers and the copolymer were mixed with nitrocellulose and evaluated using thermal analysis and Bergmann–Junk techniques as propellant stabilizers in comparison with the common stabilizer, centralite 1. It was found that the homopolymer containing the p‐nitro group is a superior stabilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2808–2819, 2002
Cure kinetics of the cardanyl acrylate–styrene system using isothermal differential scanning calorimetry
Authors: Nguyen Le Huong , Koerner Hilmar , Lederer Klaus
Published: October 2002

The curing kinetics of styrene (30 wt %) and cardanyl acrylate (70 wt %), which was synthesized from cardanol and acryloyl chloride, was investigated by differential scanning calorimetry under isothermal condition. The method allows determination of the most suitable kinetic model and corresponding parameters. All kinetic parameters including the reaction order, activation energy Ea and kinetic rate constant were evaluated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2034–2039, 2002
Electrically conductive semi‐IPNs based on polyaniline and crosslinked polyvinylacetate
Authors: Ma Junqing , Song Huihong , Frisch Harry L. , Maaref Shahin , Sun Sam. S.
Published: October 2002

Electrically conductive semi‐IPNs based on polyaniline and crosslinked polyvinylacetate were prepared. Polyaniline successfully percolated through the crosslinked PVAc networks and the resulting semi‐IPNs show a continuous network morphology. The conductivity of the semi‐IPN increases with increasing content of polyaniline and increasing acidity used during the polymerization of the polyaniline. The conductivity of the semi‐IPN is 0.13 S/cm, with the highest polyaniline content of 19.3 wt %. The depression of polyaniline with temperature change is smallest followed by the depression of semi‐IPN of the polyaniline/crosslinked polyvinylacetate, which is considerably smaller than the depression of crosslinked polyvinylacetate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2287–2293, 2002
One‐step, one‐pot photoinitiation of free radical and free radical promoted cationic polymerizations
Authors: Degirmenci M. , Hepuzer Y. , Yagci Y.
Published: October 2002

We describe here a novel approach to photoinitiate free radical and cationic polymerizations concurrently, involving the use of benzoin in conjunction with an onium salt such as diphenyl iodonium or N‐alkoxy pyridinium salt. On photolysis, benzoyl radicals formed from the decomposition of benzoin initiate free radical polymerization of methyl methacrylate. The hydroxy benzyl radicals formed concomitantly are readily oxidized to the corresponding cation by the onium salt to initiate cationic polymerization of cyclohexene oxide in the same system. Evidence for two independent polymerizations was obtained from studies involving gel permeation chromatography, extractions, and infrared and proton nuclear magnetic resonance analysis of the polymers. The effect of the type of the onium salt on each polymerization was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2389–2395, 2002
Synthesis, characterization, and chelating properties of the polymacromonomer: Poly[(ethyleneglycol) methyl ether methacrylate]
Authors: Amalia Pooley S. , Rivas Bernabé L. , Maureira Antonio E.
Published: October 2002

The radical polymerization of the macromonomer poly(ethyleneglycol) methyl ether methacrylate with ammonium persulfate at 60°C was carried out. The polymer was completely soluble in water. Yield was 75%. The polymacromonomer was characterized by Fourier transform infrared, proton nuclear magnetic resonance (NMR), and 13C NMR spectroscopy. Mn, Mw, and the polydispersity were determined by gel permeation chromatography. The polymacromonomer showed a high thermal stability with a TDT50% of 420°C. The metal ion binding capacity of this polychelatogen with respect to different metal ions was investigated through the liquid‐phase polymer‐based retention (LPR) technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2929–2934, 2002
Preparation and characterization of bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane)–unsaturated polyester modified epoxy intercrosslinked matrices
Authors: Dinakaran K. , Alagar M.
Published: October 2002

An intercrosslinked network of unsaturated polyester–bismaleimide modified epoxy matrix systems was developed. Epoxy systems modified with 10, 20, and 30% (by weight) of unsaturated polyester were made by using epoxy resin and unsaturated polyester with benzoyl peroxide and diaminodiphenylmethane as curing agents. The reaction between unsaturated polyester and epoxy resin was confirmed by IR spectral studies. The unsaturated polyester toughened epoxy systems were further modified with 5, 10, and 15% (by weightt) of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were performed to determine the glass transition temperature (Tg) and thermal degradation temperature of the systems, respectively. Mechanical properties, viz: tensile strength, flexural strength, and plain strain fracture toughness of intercrosslinked epoxy systems, were studied by ASTM methods. Data obtained from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improves toughness but with a reduction in glass transition, whereas the incorporation of bismaleimide into epoxy resin improved both mechanical strength and thermal behavior of epoxy resin. The introduction of bismaleimide into unsaturated polyester‐modified epoxy resin altered thermomechanical properties according to their percentage concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2853–2861, 2002
Controlled release of biocides in solid wood. III. Preparation and characterization of surfactant‐free nanoparticles
Authors: Liu Y. , Laks P. , Heiden P.
Published: October 2002

Polymeric nanoparticles containing the fungicides tebuconazole and chlorothalonil were prepared by a simple, surfactant‐free method and found to have significantly smaller median particle diameters and more stable aqueous suspensions than their surfactant‐stabilized counterparts. These more stable suspensions were delivered into southern yellow pine and birch wood with greater efficiency than the equivalent surfactant‐stabilized nanoparticle suspensions. We found that the suspensions protected the treated wood against fungal attack by Gloeophyllum trabeum, a common brown rot wood decay fungus, and Trametes versicolor, a common white rot wood decay fungus, at low tebuconazole and chlorothalonil contents in the wood. Southern pine lost 5% or less of its mass after 55 days of exposure to G. trabeum when the tebuconazole or chlorothalonil content in the wood was only 0.4 kg/m3, while a tebuconazole or chlorothalonil content of 0.8 kg/m3 in birch wood was sufficient to bring its mass loss to less than 5% after 55 days of exposure to T. versicolor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 615–621, 2002
Synthesis and characterization of starch‐poly(methyl methacrylate) graft copolymers
Authors: Çelik Meltem , Saçak Mehmet
Published: October 2002

The graft copolymerization was carried out by methyl methacrylate with starch in which azobisisobutyronitrile was used as an initiator. The grafting reactions were carried out within a 65–95°C temperature range, and the effect of the monomer, initiator concentrations, and the amount of starch on the graft yield were also investigated. The maximum graft yield was obtained at a azobisisobutyronitrile concentration of 2.0 × 10−3 mol/L. The overall rate activation energy of the reaction was found to be 89.42 kJ/mol. The grafted starches were characterized with infrared spectroscopy, scanning electron microscopy, and thermogravimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 53–57, 2002
Enhanced strain hardening in elongational viscosity for HDPE/crosslinked HDPE blend. II. Processability of thermoforming
Authors: Yamaguchi Masayuki , Suzuki Ken‐Ichi
Published: October 2002

Rheological properties and processability of thermoforming were studied for high‐density polyethylene (HDPE) and a blend of HDPE with crosslinked HDPE (xHDPE). Blending the xHDPE, which enhances melt strength and strain hardening in elongational viscosity of HDPE, helps the sheet avoid sagging in thermoforming. Moreover, the product of the blend obtained by vacuum forming has uniform wall thickness. Melt strength and strain hardening of the blend were, however, depressed by a processing history in a single‐screw extruder, whereas reprocessing by a two‐roll mill enhanced the melt strength again. It is considered that the processing history by a single‐screw extruder, in which shear‐dominant flow takes place, depresses the trapped entanglements between network chain of xHDPE and linear HDPE molecules, and results in low level of melt strength. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 79–83, 2002
Rheological characterization of cellulose solutions in N‐methyl morpholine N‐oxide monohydrate
Authors: Chae Dong Wook , Kim Byoung Chul , Lee Wha Seop
Published: October 2002

Three different modes of rheological properties were measured on 11 and 13 wt % solutions of cellulose in N‐methyl morpholine N‐oxide (NMMO) monohydrate, in which concentration range lyocell fibers of much reduced fibrillation are preferably produced. The dynamic rheological responses revealed that the Cox–Merz rule did not hold for these cellulose solutions. Both cellulose solutions showed a shear thinning behavior over the shear rate measured at 85, 95, 105, and 115°C. However, 13 wt % solution gave rise to yield behavior at 85ºC. The power law index ranged from 0.36 to 0.58. First normal stress difference (N1) was increased with lowering temperature and with increasing concentration as expected. Plotting N1 vs shear stress (τω) gave almost a master curve independent of temperature and concentration, whose slope was about 0.93 for both cellulose solutions over the shear rate range observed (τω > 500 Pa). In addition, the cellulose solutions gave high values of recoverable shear strain (SR), ranging from 60 to 100. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 216–222, 2002
Morphology and mechanical properties of polypropylene/maleated styrene–butadiene–styrene triblock copolymer blends
Authors: Wilhelm Helena Maria , Felisberti Maria Isabel
Published: October 2002

The morphology and mechanical properties of blends of isotactic polypropylene (i‐PP) and a maleated butadiene–styrene–butadiene triblock copolymer with maleic anhydride (SBS–MAH), i‐PP/SBS–MAH, were investigated and compared with those of corresponding blends of i‐PP and a styrene–butadiene–styrene triblock copolymer (SBS), i‐PP/SBS. The blends were prepared in a mixer at 190°C with 5–25 wt % elastomer compositions. The blends exhibited a two‐phase morphology with a disperse elastomer phase in the continuous i‐PP matrix. The size and shape of the elastomer particles and the mechanical properties of the blends depended on the nature and concentration of the elastomer. The i‐PP/SBS–MAH blends showed an impact strength superior to that of the corresponding i‐PP/SBS blends. These results were attributed to the formation of the graft copolymer during the melt blending, which was verified by Fourier transform infrared. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 359–365, 2002
Micro‐ and nanomorphologies of isotactic polystyrene revealed by PLM, AFM, and TEM
Authors: Liu Tianxi , Ma Kuixiang , Liu Zhehui , He Chaobin , Chung Tai‐Shung
Published: October 2002

The spherulitic and lamellar morphologies of isotactic polystyrene (iPS) isothermally crystallized from the glassy state were investigated by polarized light microscopy (PLM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The AFM phase images and TEM bright‐field electron micrographs revealed that the iPS spherulites consist of a number of dominant edge‐on lamellae which continuously grow outward by splaying and branching. By partial melting, the less perfect subsidiary lamellae, which are formed within the framework of the dominant ones due to the growth in restricted spaces and possess lower thermal stability than that of the dominant ones, were directly observed by TEM. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 422–427, 2002