bluuebunny/crossref_metadata_2025 huggingface dataset:
Secular trend in the development of fatness during childhood and adolescence
Authors: Thompson Angela M. , Baxter‐Jones Adam D.G. , Mirwald Robert L. , Bailey Donald A.
Published: September 2002

This study examined the development of fatness, as indexed by skinfold thickness, in healthy Caucasian children and adolescents residing in the same location in Canada in the 1960s and the 1990s. The data comes from two longitudinal studies, conducted approximately 30 years apart, of children aged 8–16 years. The first study (1964–1973) annually measured 207 males and 140 females. The second investigation (1991–1997) repeatedly measured 113 males and 115 females. Identical measurement tools and protocols were used for height, body mass, and skinfolds. Maturational age was estimated as a measure in years from age of peak height velocity. Males from the second investigation matured significantly (P < 0.05) earlier. Multilevel regression modeling was utilized to determine developmental curves for the individuals within the two populations. When differences in height, body mass, and maturity were controlled, skinfold thicknesses of the males and females in the second study were significantly greater (P < 0.05) than age‐ and sex‐matched peers in the first study. This was not seen in models of the BMI. The results suggest that when maturity and size were controlled, the fatness of children and adolescents increased over 30 years. Am. J. Hum. Biol. 14:669–679, 2002. © 2002 Wiley‐Liss, Inc.
Changing family structure in a modernizing society: A study of marriage patterns in a single Muslim village in Israel
Authors: Zlotogora J. , Habiballa H. , Odatalla A. , Barges S.
Published: September 2002

Among 1,875 couples from one Muslim village, 374 (20%) marriages were between first cousins. Among women born after 1920, the highest rates of first‐cousin marriages were observed among those born between 1940–1959 (26%) and this pattern declined in the last two decades. The majority of first‐cousin marriages were between offspring of brothers. Analyzed by 20‐year periods, the pattern of first‐cousin marriages changed as the proportion of marriages between brothers' children decreased from 75% to 44%. Over the study period, more than 70% of marriages were between individuals born in the village and related to some degree. Examination of the marriages in which both spouses were born in the village demonstrated a preference to marry within the extended family; 68% of the women married a man with the same family name. Since the creation of the Israeli State, there have been significant changes among Israeli‐Arab citizens. However, these data demonstrate that the tradition of marrying a relative remains central, although some changes in marriage preference have occurred. Am. J. Hum. Biol. 14:680–682, 2002. © 2002 Wiley‐Liss, Inc.
HFE based re‐evaluation of heterozygous hemochromatosis
Authors: Moirand Romain , Guyader Dominique , Mendler Michel Henry , Jouanolle Anne Marie , Le Gall Jean Yves , David Véronique , Brissot Pierre , Deugnier Yves
Published: September 2002

Homozygosity for the C282Y mutation in the HFE gene is strongly associated with hereditary hemochromatosis. More than one subject out of 10 in the general population is a heterozygote for the C282Y mutation. In this study, we address whether or not conclusions drawn from HLA‐based family studies regarding the expression of heterozygous hemochromatosis are applicable to C282Y heterozygotes. The correlation between HLA‐inferred and HFE genotypes and the variation of serum iron tests according to HFE genotype and other factors were studied in persons from well‐characterized hemochromatosis pedigrees. Subjects were tested for both C282Y and H63D mutations. The following factors were studied: age, sex, alcohol consumption, body mass index, liver function tests, serum lipids and glucose, serum iron, transferrin saturation, and ferritin. HLA‐inferred heterozygotes were C282Y heterozygotes in only 70% and compound heterozygotes (i.e., heterozygotes for both C282Y and H63D) in 20%. C282Y heterozygotes did not differ from wild type homozygotes in terms of serum iron tests. Only compound heterozygotes presented with slightly increased transferrin saturation. On the other hand, increased serum ferritin was strongly associated with overweight or lipidic or glucose abnormalities. C282Y heterozygotes selected from family studies do not have greater serum iron tests than wild type homozygotes, except for compound heterozygotes, and therefore should not require special followup. The discovery of abnormal iron tests in a C282Y heterozygote should lead to workup for other causes of iron overload. © 2002 Wiley‐Liss, Inc.
Diagnostic dilemmas in the short rib–polydactyly syndrome group
Authors: Elçioglu Nursel H. , Hall Christine M.
Published: September 2002

The short rib–polydactyly syndromes are a group of lethal skeletal dysplasias with autosomal recessive inheritance characterized by markedly short ribs, short limbs, usually polydactyly, and multiple anomalies of major organs. At least four types have been recognized. The radiological findings of 10 cases are presented. Each fetus or stillbirth has some of the radiological features of the four established types of short rib–polydactyly syndrome and raises diagnostic dilemmas in differentiating these entities. The overlapping phenotypes of these fetuses supports the previously suggested hypothesis that the different subtypes of the short rib–polydactyly syndrome group are not single entities, but rather part of a continuous spectrum with variable expressivity. © 2002 Wiley‐Liss, Inc.
Identification of uniparental disomy in phenotypically abnormal carriers of isochromosomes or Robertsonian translocations
Authors: Berend Sue Ann , Bejjani Bassem A. , McCaskill Christopher , Shaffer Lisa G.
Published: September 2002

Carriers of either homologous or non‐homologous acrocentric rearrangements are at an increased risk for aneuploidy, and, thus, for uniparental disomy (UPD). Abnormal phenotypes due to genomic imprinting are associated with UPD for the acrocentric chromosomes 14 and 15. The purpose of this study was to determine the prevalence of UPD in a population with acrocentric rearrangements (either an isochromosome or a Robertsonian translocation) and abnormal phenotypes. Fifty individuals were studied. Of the 50 rearrangements, two were homologous rearrangements and both showed UPD. Forty‐eight were non‐homologous Robertsonian translocations, of which two showed UPD. This study demonstrates that UPD explains the abnormal phenotypes in some balanced carriers of acrocentric rearrangements. Our results and the large number of case reports in the literature suggest that patients with abnormal phenotypes and acrocentric rearrangements of chromosomes 14 or 15 should be tested for UPD. © 2002 Wiley‐Liss, Inc.
Review and meta‐analysis of systematic searches for uniparental disomy (UPD) other than UPD 15
Authors: Kotzot Dieter
Published: September 2002

All systematic searches for uniparental disomy (UPD) so far published and comprising clinically defined populations (Silver‐Russell syndrome/primordial growth retardation (SRS/PGR) (n = 14), multiple malformations (n = 2), or rare syndromes (n = 12)) or situations at risk (confined placental mosaicism (CPM) (n = 13), spontaneous abortions (n = 6), additional marker chromosomes (n = 15), balanced non‐Robertsonian translocations (n = 3), or balanced Robertsonian translocations (n = 15)) were reviewed. In many studies clinical and/or cytogenetic information on fluorescent in situ hybridization (FISH) results was very scarce. Meta‐analysis concerning an adequate number of cases was possible for SRS/PGR, CPM, additional marker chromosomes, and balanced Robertsonian translocations only. As expected, the highest risk for UPD was found in cases with translocations between homologous acrocentric chromosomes (11 cases with UPD of 15 investigated) and in CPM due to a meiotic error (25 of 51 cases).

In prenatal investigations or in cases with a normal phenotype, translocations between nonhomologous acrocentric chromosomes implied a risk for UPD of less than 0.5%. The risks for maternal UPD 7 in cases with SRS/PGR, for UPD 15 in cases with an additional inv dup(15) marker chromosome, and for UPD of any chromosome in cases with multiple malformation/mental retardation were approximately 5.5%, and approximately 1.3%, respectively. Searches for UPD in well‐defined syndromes (Brachmann‐De Lange syndrome, Sotos syndrome, Rett syndrome, Weaver syndrome, or XX true hermaphroditism) were disappointing. Not a single case was found. © 2002 Wiley‐Liss, Inc.
Familial reciprocal translocation t(7;16) associated with maternal uniparental disomy 7 in a Silver‐Russell patient
Authors: Dupont Jean‐Michel , Cuisset Laurence , Cartigny Maryse , Le Tessier Dominique , Vasseur Christian , Rabineau Didier , Jeanpierre Marc
Published: September 2002

We present the case of a maternal heterodisomy for chromosome 7 in the daughter of a t(7;16)(q21;q24) reciprocal translocation carrier. The proband was referred to the hospital for growth retardation and minor facial dysmorphism without mental retardation. A diagnosis of Silver‐Russell syndrome was suspected. Chromosomal analysis documented a 46,XX,t(7;16)(q21;q24)mat chromosome pattern. Microsatellite analysis showed a normal biparental inheritance of chromosome 16 but a maternal heterodisomy of chromosome 7. Occurrence of uniparental disomy (UPD) is a well‐recognized consequence of chromosomal abnormalities that increase the rate of meiotic nondisjunction, mainly Robertsonian translocations and supernumerary chromosomes. Although reciprocal translocations should, theoretically, be also at increased risk of UPD, only three cases have been reported so far. However, because the association between uniparental disomy and reciprocal translocation may exist with an underestimated frequency, prenatal diagnosis is recommended when clinically relevant chromosomes for UPD are involved. © 2002 Wiley‐Liss, Inc.
Coffin‐Lowry syndrome: A 20‐year follow‐up and review of long‐term outcomes
Authors: Hunter Alasdair G.W.
Published: September 2002

The Coffin‐Lowry syndrome has become well established since the first report of affected patients by Coffin et al. [1966: Am J Dis Child 112:205–213]. Since that time over a hundred cases have been reported and the responsible gene has been identified. However, there remains a paucity of long‐term follow‐up information on older patients with which to counsel affected families about prognosis. There is also much to be learned about genotype‐phenotype correlations. In 1982 we reported 12 patients (including carrier mothers) from eight families, one of whom had died about the time the paper was written. Recently, we have been able to obtain follow‐up information on six of the affected patients and one of the carrier mothers. A number of important complications have occurred, including premature death, loss of ambulation, and quadriplegia. This paper updates the medical histories of our patients and summarizes the clinically important complications that have been reported in patients with Coffin‐Lowry syndrome. There are few data on patients over the age of 30, and much more longer term follow‐up is required. © 2002 Wiley‐Liss, Inc.
Early detection of severe cholestatic hepatopathy in COACH syndrome
Authors: Foell Dirk , August Christian , Frosch Michael , Harms Erik , Zimmer Klaus‐Peter
Published: September 2002

COACH syndrome is a disorder with cerebellar vermis hypoplasia, oligophrenia, ataxia, coloboma, and hepatic fibrosis. Sixteen cases with certain COACH diagnosis have been reported so far. Neurologic abnormalities are the first symptoms in most cases. The majority of cases were diagnosed late in childhood or adolescence. Complications of the hepatopathy contribute extensively to the morbidity and lethality in the course of the disease. Major complications are portal hypertension, esophageal varices, and gastrointestinal bleeding. We report of a child with only mild neurologic symptoms, but severe hepatic fibrosis with cholangiopathy, and review the literature. This is the first description of profound cholestatic hepatopathy in a very young child with COACH syndrome. The patient was found to have cerebellar vermis hypoplasia, unilateral optical nerve coloboma, mild dysmorphic signs, and a ventricular septum defect. Routine laboratory investigations eventually revealed elevated liver enzymes. Prothrombin time was abnormal. Ultrasound scan of the liver was normal. Hepatotropic viral infections were excluded. We performed a liver biopsy at the age of 16 months, confirming an early stage of cirrhosis with septal fibrosis and pseudolobules, inflammatory infiltrates, signs of cholestasis, and reduced numbers of intrahepatic bile ducts. Early detection and differentiation of liver pathology are important in COACH syndrome. Progressive destructive cholangiopathy may contribute to hepatic fibrosis in COACH syndrome. Liver disease can be severe even in cases with mild neurologic deficits. © 2002 Wiley‐Liss, Inc.
Behavioral phenotypes in four mental retardation syndromes: Fetal alcohol syndrome, Prader‐Willi syndrome, fragile X syndrome, and tuberosis sclerosis
Authors: Steinhausen Hans‐Christoph , von Gontard Alexander , Spohr Hans‐Ludwig , Hauffa Berthold P. , Eiholzer Urs , Backes Margitta , Willms Judith , Malin Zeno
Published: September 2002

Behavioral phenotypes were studied in four mental retardation syndromes using the Developmental Behavior Checklist (DBC). The four samples comprised fetal alcohol syndrome (FAS), Prader‐Willi syndrome (PWS), fragile X syndrome (FRAX), and tuberosis sclerosis (TSC). Both on the item and the subscale level, there were clear behavioral differentiations across the four syndromes. FAS and FRAX proved to be most clearly differentiated from the other two samples, with PWS and TSC showing lower scores and less abnormal behavior profiles. Neither intelligence nor gender nor age contributed to variations in the number of behavior abnormalities. It was concluded that the DBC as a quantitative approach contributes significantly to the differentiation of behavioral phenotypes in various mental retardation syndromes. © 2002 Wiley‐Liss, Inc.
Sequential culture medium promotes the in vitro development of Macaca fascicularis embryos to blastocysts
Authors: Curnow E.C. , Pawitri D. , Hayes E.S.
Published: September 2002

In vitro production of blastocyst stage embryos from Macaca fascicularis (Mf) has not previously been demonstrated without cell support. Historical data indicates that a large proportion of Mf embryos arrest at the morula stage in nonsequential culture medium (NSM) lacking serum supplementation and/or cell support. Here we report the application of a sequential culture system supporting in vitro production of Mf blastocysts. Mf embryos produced by in vitro fertilization (IVF; n = 69) were subjected to in vitro culture without cell support in either a commercial sequential embryo culture medium (SM) or an NSM. At 24hr post‐insemination (PI) embryos generated from in vivo and in vitro matured oocytes and cultured in the NSM cleaved to two or more cells in significantly greater proportions (15/23; 65%) compared to embryos cultured in SM (14/46; 30%). However, by day 3 PI embryo development beyond eight cells was not different in NSM (9/23; 39%) compared to SM (25/46; 54%). At day 5 PI embryo development to the morula stage was slightly lower in NSM (8/23, 35%) compared to SM (21/46, 45%), and embryo degeneration was slightly higher in NSM (9/23, 39%) compared to SM (9/46, 20%). After 7–9 days of in vitro culture, embryo development to the blastocyst stage and embryo degeneration were significantly lower and higher, respectively, in NSM (0/23, 0%; and 23/23, 100%) compared to SM (9/46, 20%; and 26/46, 56%). In this study the sequential culture system was better able to support in vitro development of Mf embryos compared to nonsequential culture systems. Am. J. Primatol. 57:203–212, 2002. © 2002 Wiley‐Liss, Inc.
Response patterns of bonnet macaques following up to 75 weeks of continuous access to social‐video and food rewards
Authors: Andrews Michael W. , Rosenblum Leonard A.
Published: September 2002

Three individually housed bonnet macaque males were given 75 weeks of continuous access to a joystick task with a reward choice of either viewing live color video of a bonnet group or obtaining a banana‐flavored food treat. Here we report data for weeks 44–75 following a change in the stimulus group displayed in the video. The new stimulus group enhanced responding to the video for two subjects over the entire 32 weeks of this study, although there was some decline across weeks, and the video continued to be an effective reward for the duration of the study for all subjects. Am. J. Primatol. 57:213–218, 2002. © 2002 Wiley‐Liss, Inc.
Disappearances of individuals from social groups have implications for understanding natal dispersal in monogamous owl monkeys (Aotus azarai)
Authors: fernandez‐Duque Eduardo , Huntington Caleb
Published: September 2002

The socially monogamous owl monkeys (Aotus spp.) live in small groups of two to five individuals. We used monthly demographic data collected from 16 social groups between 1997–2001 to estimate the age of disappearance from their natal groups and the timing of those disappearances in a population of owl monkeys (Aotus azarai azarai) in Formosa, Argentina. We applied survival analysis techniques to 48 months of observations of 47 individuals to construct age‐specific probabilities of disappearance. Two‐thirds of the individuals (eight of 12), for which disappearance could be well timed, disappeared at around 2 years of age. The average age at disappearance for these individuals was 29 months (±8), whereas the mean age of disappearance obtained from the survival analysis of censored and uncensored data was almost 3 years (mean±SD, 35±3 months). Ninety‐two percent of all disappearances of adult size individuals (11 of 12) occurred around the birth season. Our data suggest that at least some individuals disperse soon after sexual maturation while others remain for up to 4 years in their natal groups. Am. J. Primatol. 57:219–225, 2002. © 2002 Wiley‐Liss, Inc.
Social system of the Alaotran gentle lemur (Hapalemur griseus alaotrensis): genetic characterization of group composition and mating system
Authors: Nievergelt Caroline M. , Mutschler Thomas , Feistner Anna T.C. , Woodruff David S.
Published: September 2002

Group composition and mating system were investigated in wild Alaotran gentle lemurs (Hapalemur griseus alaotrensis) using genetic markers. These small‐bodied herbivorous and cathemeral primates are endemic to the reed and papyrus beds around Lac Alaotra in Madagascar. They live in small groups in small, defended territories. Data were collected during the rainy seasons in 1996, 1997, and 1999, and include 99 individuals from 22 neighboring social groups and an additional 30 animals from other areas representing most of the geographic range. Animals were located by researchers canoeing in the marshes bordering the lake. After a group's size was determined by direct observation, all individuals were captured, marked, and released. During handling each individual was weighed and sexed, and hair samples for DNA extraction were collected. A 342 bp mtDNA control region sequence and 10 nuclear microsatellite loci provided multilocus genotypes that were used to assess pedigree relations and population structure. Alaotran gentle lemurs were found in groups of two to nine individuals (mean: 4.3), comprising one or two breeding females, their offspring, and one reproducing male. Solitary individuals of both sexes were encountered rarely. Breeding females were the permanent core of the social groups, whereas intergroup transfer of reproductive males was relatively frequent. Forty percent of all reproducing groups contained two breeding females, which were related to each other as closely as mother–daughter or full sisters. Parentage assessment revealed a variable mating system ranging from serial monogamy to polygyny within social groups. At least 8% of paternities involved extragroup males. Additional data on life history and reproduction are presented, and the social system of the Alaotran gentle lemur is discussed in the light of the new genetic findings. Am. J. Primatol. 57: 157–176, 2002. © 2002 Wiley‐Liss, Inc.
Semicontinuous emulsion polymerization of vinyl acetate: Effect of ethoxylation degree of nonionic emulsifiers
Authors: Sarac Ayfer , Erbil H. Yildirim , Yildirim Hüseyin
Published: September 2002

Poly(vinyl acetate) latices were prepared in the presence of an ammonium persulfate initiator, 10–50 mol of an ethoxylated nonylphenol nonionic emulsifier, and a poly(vinyl alcohol) colloid stabilizer by applying semicontinuous emulsion polymerization (delayed monomer and initiator addition process) in a laboratory scale similar to industrial practice. Two approaches were applied: the molar concentration of the nonionic emulsifier was kept constant and the weight ratios in the polymerization recipe varied or the weight ratios were kept constant. The effects of the change in the ethoxylation degree of the emulsifier to the final latex viscosity, average polymer molecular weight, polymer grafting degree, surface tension of the latex, and the surface free energy of the dried films were investigated. It was determined that the resultant latex viscosity decreases and the viscosity‐average polymer molecular weight increases with increase of the nonionic emulsifier ethoxylation degree. The increase of the ethoxylation degree does not seriously affect the surface tension of the resultant latex or the surface free energy of the dried poly(vinyl acetate) films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 844–851, 2002
Rheology of polyflavonoid tannin–formaldehyde reactions before and after gelling. II. Hardener influence and comparison of different tannins
Authors: Garnier S. , Pizzi A. , Vorster O. C. , Halasz L.
Published: September 2002

Good correspondence of the gel‐time values obtained by two different methods, G′ = G″ and 1/η0→0, was observed for different types of natural and modified tannin extracts. The pH presents the predominant effect on both the activation energies and the gel times observed, while the proportion of a paraformaldehyde hardener has a much lesser effect on these parameters. The rate constants of the different phases of the reaction of polycondensation with formaldehyde, both before and after the gel point, were obtained for the six commercial tannin extracts tested. The viscoelastic properties of the different tannins/formaldehyde gels were measured. The gel stiffness S, relaxation coefficient n, and relaxation time λ were determined and their dependence on the proportion of the formaldehyde hardener, on the temperature, and on the type of tannin was determined. The gel stiffness S appears to be influenced considerably by the proportion of the formaldehyde hardener. Its value decreased as the percentage of the hardener increased: This was due to early network immobilization and the resulting lower level of crosslinking resulting from it. The influence on S of the temperature is not very pronounced. The relaxation coefficient n appears to depend mainly on the reactivity of the tannin used: The faster the reactivity, the higher was the value of n. This appears to be valid exclusively in tannin extracts where the colloidal state is still present, while it is not valid in extracts where the colloidal state was eliminated by, for example, solvent extraction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 864–871, 2002
Rheology of polyflavonoid tannin–Formaldehyde reactions before and after gelling. I. Methods
Authors: Garnier S. , Pizzi A. , Vorster O. C. , Halasz L.
Published: September 2002

The gelling and hardening reactions of different, commercial polyflavonoid tannin extracts of the prorobitenedin/profisetinidin, procyanidin, and prodelphinidin types with formaldehyde were studied by parallel‐plate rheometry. To do this, methods to determine the rheological characteristics of tannin–formaldehyde polycondensation reactions both before and after the gel point were developed. The validity of some modifications of known methods was checked on the best‐known commercial tannin extract, namely, the reaction of the mimosa tannin extract with 5% paraformaldehyde, over a range of different temperatures. The gel point was determined by three different methods, namely, by the crossover point of viscous and elastic moduli, by the extrapolation to ∞ of the zero‐frequency viscosity, and by determining the point at which the value of tan δ is constant whatever frequency is used in the measurement. The results obtained were critically compared. The comparisons obtained were good and were reproducible when the first two methods were used, but not when the third one was used. This allowed the determination of the energy of activation at different stages in the tannin–aldehyde polycondensation reaction and the calculation of the degree of conversion of the tannin–aldehyde polycondensation before, at, and after the gel point. Mathematical expressions defining the degree of conversion for tannin–aldehyde reactions before, at, and after the gel point as a function of different moduli were developed and checked with the experimental data obtained. Methods and mathematical expressions for the determination of the rate constants of the different stages of the reaction were also developed and checked. After the gel point, the system was modeled using both a diffusion‐controlled model and a second‐order kinetic law. The applied results obtained indicated that, although a certain element of diffusion control is present, a second order, diffusion‐independent kinetic is more valid under the experimental conditions used. This indicates that the rheometry approach to a polycondensation network is limited mostly by the capability of the equipment to the region after the gel point, where diffusion control does not as yet play a predominant role. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 852–863, 2002
Challenges in forming successful mixed matrix membranes with rigid polymeric materials
Authors: Mahajan Rajiv , Burns Ryan , Schaeffer Michael , Koros William J.
Published: September 2002

Mixed matrix materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane materials. It has been shown that successful mixed matrix materials can be formed using relatively low glass transition (Tg) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid matrix polymers with high Tgs that can ultimately be used in forming high‐performance mixed matrix layers for composite membranes. Initial attempts to form mixed matrix materials based on high Tg polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting this problem was pursued in this study by forming the composite material close to the Tg of the polymer by addition of a plasticizer to match the matrix Tg with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A–Matrimid®/plasticizer membranes, and this data compares favorably with predictions of the well‐known Maxwell model for composite systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 881–890, 2002
The rheological behavior of immiscible polymer blends
Authors: Choi Gwan‐Young , Kim Ho‐Gyum , Kim Young‐Ho , Seo Chang‐Wook , Choi Jin‐Hwan , Han Dong‐Hee , Oh Dae‐Hee , Min Kyung‐Eun
Published: September 2002

The complex shear modulus of immiscible polymer blends was measured by a frequency sweep experiment for polystyrene (PS)/low density polyethylene (LDPE) and poly(methylmethacrylate) (PMMA)/LDPE blends at constant composition (13.5/86.5 vol %) and compared with the prediction model of Palierne. Different morphologies of each blend were also prepared using a rheometer with a constant shear rate and different strain. There was morphological dependency on the complex shear modulus at constant temperature. However, this dependency disappeared at specific temperatures in the frequency sweep experiment. There seemed to be a specific temperature like critical flow temperature (Tcf) of amorphous polymer. The difference in morphology affected the complex shear modulus of blends below the specific temperature, Tcf, but did play a major role in determining the complex shear modulus of blends at over specific temperature. A new method may be needed to determine the critical flow temperature of an amorphous polymer via the measurement of a complex shear modulus for immiscible polymer blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 917–924, 2002
Modified cellulose fibers prepared by the N‐methylmorpholine‐N‐oxide (NMMO) process
Authors: Niekraszewicz B. , Czarnecki P.
Published: September 2002

Cellulose fibers with modified properties have been prepared from cellulose solutions in N‐methylmorpholine‐N‐oxide (NMMO). Poly(ethylene oxide) as a hydrophilic modifier and polyethylene as a hydrophobic modifier were added to the spinning solution. Based on microscope examination and measurements of such properties of fibers as porosity, moisture absorption, water retention, and tensile strength, structural changes as well as physical and mechanical properties of the resultant fibers depending on the amount of modifier added to the spinning solution were analyzed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 907–916, 2002
Comparison of polycarbonate precursors synthesized from catalytic reactions of bisphenol‐A with diphenyl carbonate, dimethyl carbonate, or carbon monoxide
Authors: Kim Won Bae , Lee Jae Sung
Published: September 2002

Transesterification of bisphenol‐A with diphenyl carbonate or dimethyl carbonate, and direct oxidative carbonylation of bisphenol‐A were compared to obtain polycarbonate precursors for phosgene‐free polycarbonate synthesis. The melt‐transesterification of bisphenol‐A and diphenyl carbonate occurred readily to produce reactive precursors without a significant equilibrium constraint. On the other hand, the transesterification of bisphenol‐A and dimethyl carbonate showed a serious equilibrium limitation in obtaining reactive polycarbonate precursors leading to high molecular weight polymers, and coproduced a significant amount of methylated bisphenol‐A. The direct oxidative carbonylation of bisphenol‐A with CO produced diphenolic‐ended oligomers and a significant amount of by‐products, which are the least reactive in the subsequent polycondensation step of the phosgene‐free polycarbonate process. A novel method to synthesize the reactive polycarbonate precursors was proposed that employed the coupled oxidative carbonylation of both bisphenol‐A and phenol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 937–947, 2002
Poly(ethylene glycol) electrolyte gels prepared by condensation reaction
Authors: Koo Jahyun , Kim Dukjoon
Published: September 2002

Poly(ethylene glycol) electrolyte gels were prepared by condensation reaction in the presence of tetraethoxysilane. Differential scanning calorimetry and X‐ray diffraction spectroscopy were used to investigate the thermal transition behavior and crystalline structure of polymer gels prepared. Both formation of crosslinks and incorporation of salts or plasticizers reduced the development of crystalline structure of poly(ethylene glycol)s. Cyclic voltammetric and ion‐conducting behaviors of polymer gels were analyzed using potentiostat and impedance spectroscopy, and those were also considerably affected by the crosslinking density of polymers and the concentration of electrolyte salt or plasticizers incorporated. Poly(ethylene glycol) gels possessing certain levels of electrolyte salt and plasticizer were expected to have applications of solid electrolytes for lithium polymer secondary batteries. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 948–956, 2002
Preparation and characterization of novolac type phenolic resin blended with poly(dimethylsiloxane adipamide)
Authors: Hung Albert Y. C. , Wang Feng‐Yih , Ma Chen‐Chi M. , Sun Yih‐Min
Published: September 2002

Phenolic resin/poly(dimethylsiloxane adipamide) (PDMSA) blends, which have been prepared, show miscibility due to intermolecular H‐bonding existing between phenolic resin and the PDMSA. The specific H‐bonding of novolac type phenolic/PDMSA blends was characterized by means of glass transition temperature behavior and Fourier Transform Infrared Spectroscopy (FTIR). The strength of intermolecular H‐bonding within the phenolic blend is a function of the H‐bonded group of the PDMSA modifier and corresponds to the deviation glass transition temperature (ΔTg). Phenolic/PDMSA blends were completely miscible, as confirmed by the Tg study. The FTIR result is in good agreement with the inference from Tg behavior. The char yield of phenolic/PDMSA corresponds to the phenolic resin content. The molecular mobility of phenolic/PDMSA blends increases with PDMSA content in the phenolic‐rich region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 984–992, 2002
Studies on photosensitive homopolymer and copolymers having a pendant photocrosslinkable functional group
Authors: Balaji R. , Nanjundan S.
Published: September 2002

The methacrylate monomer 4‐methyacryloyloxyphenyl‐3′,4′‐dimethoxystyryl ketone (MPDMSK), having a free‐radical polymerizable group and a photocrosslinkable functional group, was synthesized. The homopolymer and copolymers of MPDMSK with glycidyl methacrylate were synthesized by free‐radical solution polymerization. The structures of the newly synthesized monomers, homopolymer, and copolymers were confirmed by different spectroscopic techniques. The average molecular weights of the polymers were determined by gel permeation chromatography. The thermal stability of the polymers was measured by thermogravimetric analysis in air and the glass‐transition temperatures were determined by differential scanning calorimetry under nitrogen atmosphere. The copolymer compositions were determined by 1H‐NMR analysis. The monomer reactivity ratios were determined by the application of conventional linearization methods such as Fineman–Ross, Kelen–Tüdös, and extended Kelen–Tüdös methods. The photoreactivity of both the homopolymer and the copolymers having pendant chalcone moieties was studied in various solvents. The effects of various factors such as solvents, concentrations, copolymer ratios, and photosensitizers on the rate of photocrosslinking of the newly synthesized polymers were investigated and the results were discussed for using the polymers as negative photoresists. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1023–1037, 2002
Optimal reaction conditions for the minimization of energy consumption and by‐product formation in a poly(ethylene terephthalate) process
Authors: Ha Kyoung‐Su , Rhee Hyun‐Ku
Published: September 2002

We determined the optimal reaction conditions to minimize the energy cost and the quantities of by‐products for a poly(ethylene terephthalate) process by using the iterative dynamic programming (IDP) algorithm. Here, we employed a sequence of three reactor models: the semibatch transesterification reactor model, the semibatch prepolymerization reactor model, and the rotating‐disc‐type polycondensation reactor model. We selectively chose or developed the reactor models by incorporating experimentally verified kinetic models reported in the literature. We established the model for the entire reactor system by connecting the three reactor models in series and by resolving some joint problems arising when different types of reactor models were interconnected. On the basis of the simulation results of the reactor system, we scrutinized the cause and effect between the reaction conditions and the final quality of the polymer product. Here, we set up the optimization strategy by using IDP on the basis of the integrated reactor model, and the process variables with significant influence on the properties of polymer were selected as control variables with the help of a simulation study. With this method, we could refine the reaction conditions at the end of each iteration step by contracting the spectra of control regions, and the iteration process finally stopped when the profile of the optimal trajectory converged. We also took the constraints on the control variables into account to guarantee polymer quality and to suppress side reactions. Constituting six different strategies by setting weighting vectors differently, we examined the differences in optimal trajectories, the trend of optimality, and the quality of the final polymer product. For each of the strategies, we conducted the optimization to examine whether the number‐average degree of polymerization approached the desired value. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 993–1008, 2002
Influence of the crystallization conditions on the morphology of the contact layer of polyethylene crystallized on graphite: Atomic force microscopy studies
Authors: Tracz Adam , Jeszka Jeremiasz K. , Kucińska Iwona , Chapel Jean‐Paul , Boiteux Giséle , Kryszewski Marian
Published: September 2002

The influence of crystallization conditions on the morphology of the contact layer of high‐density polyethylene crystallized on graphite has been investigated. The characteristic morphology of the polyethylene contact layer consists of striated, ribbonlike structures organized in domains in which the striations follow the same direction. The directions in different domains reflect the threefold symmetry of the graphite lattice. From the dependence of the width of ribbons on the crystallization conditions (i.e., the cooling rate and annealing), it has been concluded that the polymer chain is aligned parallel to the striation directions and that the ribbon width corresponds to the lamellar width. Therefore, the lamellar width in the contact layer (60 and 80 nm for cooling rates of 10 and 0.2°/min, respectively) is considerably bigger than in the bulk (ca. 26 nm). In addition, the chain orientation can be uniform over large areas, but the domain orientation can be disturbed by the presence of pits only one atomic layer deep (0.335 nm) if they are formed on the graphite surface. These results show the great importance of the nanostructure of the support for polymer chain alignment and epitaxial crystallization of polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1329–1336, 2002
Transformation of polyethylene crystals by high‐pressure annealing
Authors: Kazmierczak T. , Galeski A.
Published: September 2002

We investigated the possibility of obtaining high‐density polyethylene (PE) samples with crystals in a broad range of thicknesses. PE samples solidified by slow cooling were subjected to hydrostatic pressure at room temperature and then heated to the region of mobile pseudohexagonal form, without being passed through melting. The chains were allowed to rearrange for a period of time to a more extended chain conformation, forming larger crystals. During cooling under pressure, the transformation to orthorhombic crystals of larger thickness occurred. The thickness of the crystals was then controlled by pressure, temperature, and annealing time at high temperatures. The temperature and the pressure in the high‐pressure cell was maintained at constant level within 230–295°C and 260–630 MPa, respectively. In this way, we transformed under pressure chain‐folded PE crystals to partly chain‐extended crystals with peak melting temperatures up to 144.85°C. A range of samples with crystals 20–160 nm thick were produced and characterized with several techniques, including wide‐ and small‐angle X‐ray scattering, conventional and temperature‐modulated differential scanning calorimetry, dynamic mechanical analysis, and scanning electron, atomic force, and light microscopy as well as low‐frequency Raman spectroscopy. Changes in crystallographic unit cell dimensions were observed for crystals with different thicknesses. Crystallinity degree increased with increases in the lamellar thickness up to some level. The initial spherulitic structure deteriorated due to a multifold increase in the lamellar thickness. Oriented samples subjected to annealing in the pseudohexagonal region did not lose the crystal orientation while crystals grew thicker and the crystallinity degree increased; however, no drastic change to noncrystalline phase topology and structure was noticed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1337–1350, 2002
Modeling of polymer crystallization in plates, pipes, and rods during cooling
Authors: Piorkowska Ewa , Galeski Andrzej
Published: September 2002

We modeled crystallization of isotactic polypropylene inside plates, rods, and pipes during cooling. The modeling was based on the solution of the heat conduction equation, which takes into account the liberation of the heat of crystallization. The predictions of polymer crystallization kinetics was based on differential scanning calorimetry data and on spherulite growth rate measurements. The influence of size on the crystallization process was determined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1363–1372, 2002
Spherulitic structure development during crystallization in a finite volume
Authors: Piorkowska E. , Billon N. , Haudin J. M. , Kolasinska J.
Published: September 2002

This study was devoted to the formation of a spherulitic pattern in a confined space. Thin poly(methylene oxide) films, one wide and the second of width of average spherulite diameter, were crystallized isothermally at the same temperature and studied. In the narrow sample, the number of spherulites per unit area increased, whereas the length of interspherulitic boundary lines per unit area and the number of triple points, impingement points of three spherulites, per unit area were significantly smaller than in the wide sample. Computer simulation of the spherulitic crystallization demonstrated not only a decrease in the number of boundary lines and triple points per unit area due to limits of space available for the spherulitic nucleation and growth but also differences in the progression of the spherulitic structure formation between wide films and narrow strips. A model of the spherulitic pattern development in narrow strips of the polymer based on probability theory is elaborated. The model allows one to predict the rates of formation of the interspherulitic boundaries and also the distributions of distances from the spherulites centers to the boundaries for an isothermal and a nonisothermal crystallization. The total length of interspherulitic lines and the total number of triple points between spherulites can be also calculated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1373–1385, 2002
Crystalline and supermolecular structure of polylactide in relation to the crystallization method
Authors: Pluta Mirosław , Galeski Andrzej
Published: September 2002

The effect of thermal treatment on the crystalline and supermolecular structure of polylactide was investigated. The samples were isothermally crystallized by two methods, the crystallization temperature being reached (1) via cooling from the melt and (2) via heating from the glassy, amorphous state. The samples were crystallized over a broad temperature range of 70–130°C. The glassy state was produced by the quenching of the polymer melt to ambient temperature. The morphology and structural features of the samples were examined with X‐ray techniques (wide‐angle and small‐angle X‐ray scattering), small‐angle light scattering, polarizing light microscopy, and differential scanning calorimetry. The results showed similar structures on the lamellar level for samples prepared by the two methods under similar time and temperature conditions. Crystal perfection increased with the crystallization temperature. This was accompanied by an evolution of the spherulitic structure: the spherulites were larger in samples crystallized via cooling from the melt than those in samples crystallized via heating from the glassy, amorphous state. The thermal properties were influenced markedly by the initial crystallinity of the polymer, but differentiation of the supermolecular structures between samples crystallized according to the two protocols did not affect their thermal behavior. The structure of each sample was correlated with its viscoelastic properties. The viscoelastic response was sensitive to the crystallinity level but depended less on the sizes of the spherulites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1386–1395, 2002
Deformation of high‐density polyethylene produced by rolling with side constraints. I. Orientation behavior
Authors: Bartczak Z.
Published: September 2002

A new method of rolling with side constraints was applied to polyethylene. The process relies on the rolling of a material inside a channel formed on the circumference of one roll with another roll having a thickness matching the width of the channel in the first roll. The rolling inside a channel resembles to a large extent the plane‐strain compression in a channel die. The deformation processes of linear polyethylene by compression in a channel die and by rolling with side constraints proceed in very similar fashions and produce similarly strong single‐component crystal textures accompanied by chevronlike lamellar structures at comparable strains. The macromolecular chains are highly oriented along the rolling direction. At high rolling rates, {310} twinning takes place with both the channel die and rolling with side constraints because of tensile stress across the bar caused by strain recovery on unloading. The constraint rolling allows for the production of bars or profiles with relatively large cross sections (>1 cm2) in a continuous manner. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1396–1404, 2002
Deformation of high‐density polyethylene produced by rolling with side constraints. II. Mechanical properties of oriented bars
Authors: Bartczak Z. , Morawiec J. , Galeski A.
Published: September 2002

The mechanical behavior of oriented bars of polyethylene obtained by heavy rolling with side constraints was studied. The bars were rolled to a permanent deformation ratio (DR) of up to 8.3. The elastic modulus and ultimate strength measured along the rolling direction increase with increasing DR. For samples deformed to DR = 8.3, the ultimate strength exceeds 180 MPa, whereas an unoriented material exhibits a strength of merely 15 MPa. Because of the highly ordered lamellar structure of the rolled material, the tensile deformation of the bars along the rolling direction is reversible to a large extent. The oriented bars of polyethylene also demonstrate very high toughness, especially in the direction of side constraints. Izod impact tests revealed that the impact strength of the oriented bars exceeds 200 kJ/m2. The samples did not fracture on impact and showed only limited delamination in planes parallel to the rolling plane. Most of the delivered energy was consumed during specimen bending rather than fracture. In contrast to the tensile properties, there is an optimum DR around 5, for which the impact strength is the highest. Dynamical mechanical measurements showed that heavy rolling to a high strain, above DR = 6, produces not only a well‐developed orientation of the crystalline component but also high orientation and transverse ordering of the amorphous phase, which leads to the anisotropy of the material properties in the loading direction/constraint direction plane, perpendicular to the rolling direction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1405–1412, 2002