bluuebunny/crossref_metadata_2025 huggingface dataset:
Small familial supernumerary ring chromosome 2: FISH characterization and genotype‐phenotype correlation
Authors: Giardino Daniela , Finelli Palma , Russo Silvia , Gottardi Giulietta , Rodeschini Ornella , Atza Maria Gabriella , Natacci Federica , Larizza Lidia
Published: October 2002

A child and his mother were found to be mosaic for a small supernumerary marker chromosome (SMC) that was identified and characterized by means of fluorescent in situ hybridization. The marker chromosome was derived from the pericentromeric region of chromosome 2; the involvement of proximal 2q was determined by YAC probes. The proband was referred because of psychotic illness and mild mental retardation, whereas his mother presented only minor dysmorphisms. There are only a few published reports concerning SMC(2) or proximal 2q trisomy. We reviewed the previously reported cases in an attempt to establish genotype‐phenotype correlations, which are particularly important when SMCs are identified in prenatal diagnosis. © 2002 Wiley‐Liss, Inc.
Tardive dystonia and genetic polymorphisms of cytochrome P4502D6 and dopamine D2 and D3 receptors: A preliminary finding
Authors: Mihara Kazuo , Kondo Tsuyoshi , Higuchi Hisashi , Takahashi Hitoshi , Yoshida Keizo , Shimizu Tetsuo , Kaneko Sunao
Published: October 2002

Tardive dystonia is an uncommon but intractable and distressing complication of neuroleptic treatment. It is suggested that individual predisposing vulnerability plays a major role in the development of the side effect. This study aimed to investigate relationship tardive dystonia and several genetic factors such as polymorphism of cytochrome P4502D6, and receptor polymorphisms of dopamine D2 (TaqI A and −141C Ins/Del polymorphisms) and D3 (Ser9Gly polymorphism). Nine patients with tardive dystonia were genotyped for these genetic polymorphisms. No specific genotypes or alleles were overpresented in the patients. This study suggests that these polymorphisms are not related to the development of tardive dystonia. © 2002 Wiley‐Liss, Inc.
Brain volumes in familial and non‐familial schizophrenic probands and their unaffected relatives
Authors: McDonald Colm , Grech Anton , Toulopoulou Timothea , Schulze Katja , Chapple Ben , Sham Pak , Walshe Muriel , Sharma Tonmoy , Sigmundsson Thordur , Chitnis Xavier , Murray Robin M.
Published: October 2002

Structural brain abnormalities are consistently reported in schizophrenic subjects but the etiology of these abnormalities remains unclear. We tested the contribution of genetic predisposition and obstetric complications to the structural brain abnormalities found in schizophrenic probands and their relatives. MRI scans were carried out on 35 schizophrenic probands from families multiply affected with the disorder, and 63 of their unaffected relatives, including 10 parents who appeared to transmit genetic risk to their children; as well as 31 schizophrenic probands from families with no other affected members, 33 of their unaffected relatives; and finally 68 controls. Volumetric measurements of whole brain, lateral ventricles, third ventricle, cerebellum, and temporal lobes were completed for each subject. The impact of obstetric complications on brain structure was assessed across the gradient of presumed genetic predisposition. Both groups of schizophrenic probands displayed enlargement of the lateral and third ventricles, and there was a gradient of ventricular enlargement amongst the unaffected relatives in proportion to their likelihood of carrying schizophrenic genes. Ventricular enlargement was largely confined to males in both probands and unaffected relatives. Obstetric complications were associated with ventricular enlargement only in the familial probands. Non‐familial probands displayed reduced volume of the temporal lobes bilaterally. In families with several schizophrenic members, ventricular enlargement is a marker for genetic liability, particularly in males. Individuals inheriting the susceptibility to schizophrenia appear particularly prone to develop ventricular enlargement in response to obstetric complications. © 2002 Wiley‐Liss, Inc.
Spatial working memory deficits in schizophrenia patients and their first degree relatives from Palau, Micronesia
Authors: Myles‐Worsley Marina , Park Sohee
Published: October 2002

Spatial working memory deficits associated with dorsolateral prefrontal dysfunction have been found in Caucasian samples of schizophrenia patients and their first‐degree relatives. This study evaluated spatial working memory function in affected and unaffected members of multiplex schizophrenia families from the Republic of Palau to determine whether the spatial working memory deficits associated with schizophrenia extend to this non‐Caucasian population. Palau is an isolated island nation in Micronesia with an elevated prevalence of schizophrenia and an aggregation of cases in large multigenerational families. Our objective was to evaluate the potential for spatial working memory function to serve as one of multiple endophenotypes in a genetic linkage study of these Palauan schizophrenia families. A spatial delayed response task requiring resistance to distraction and a sensorimotor control task were used to assess spatial working memory in 32 schizophrenia patients, 28 of their healthy first‐degree relatives, and 19 normal control subjects. Schizophrenia patients and their relatives were significantly less accurate than normal control subjects on the spatial delayed response task but not on the sensorimotor control task. On both tasks, patients and relatives were slower to respond than the normal controls. There were no age or gender effects on accuracy, and working memory performance in schizophrenia patients was not significantly correlated with medication dosage. In summary, spatial working memory deficits that have been found in Caucasian schizophrenia patients and relatives were confirmed in this isolated Pacific Island family sample. These results suggest that spatial working memory deficits may be a potentially useful addition to the endophenotypic characterization of family members to be used in a comprehensive genome wide linkage analysis of these Palauan families. © 2002 Wiley‐Liss, Inc.
Alteration of branch site consensus sequence and enhanced pre‐mRNA splicing of an NMDAR1 intron not associated with schizophrenia
Authors: Hammond Linda , Castanotto Daniela , Rice Sharmon R. , Nimgaonkar Vishwajit L. , Wirshing Donna A. , Rossi John J. , Heston Leonard L. , Sobell Janet L.
Published: October 2002

Aberrant splicing of pre‐mRNA is recognized to account for a significant minority of disease‐causing mutations. The N‐methyl‐D‐aspartate receptor (NMDA) subunit gene R1 (NMDAR1) is alternatively spliced to produce eight length variants. In an examination of the NMDAR1 as a candidate gene in schizophrenia, a presumed microdeletion/insertion (del/ins) was observed in intron 10 of an African‐American male near a weak putative branch‐site consensus sequence. Although exon 10 is not known to be alternatively spliced, the del/ins was posited to alter splicing efficiency. If splicing were abolished and intron retention occurred, an in‐frame translation product of more than 250 amino acids was predicted. To explore splicing efficiency, mini genes were examined through primer‐extension analyses in NIH293 embryonic kidney cell cultures. Rather than disruption of splicing, the del/ins allele exhibited a fivefold enhancement in splicing. In an association analysis with additional schizophrenic cases and unaffected controls, all of African‐American descent, the mutant allele was observed at equivalent frequencies. A family study also did not support cosegregation of the variant allele with psychiatric disease. © 2002 Wiley‐Liss, Inc.
Mitochondrial disorders: genetics, counseling, prenatal diagnosis and reproductive options
Authors: Thorburn David R. , Dahl Hans‐Henrik M.
Published: October 2002

Most patients with mitochondrial disorders are diagnosed by finding a respiratory chain enzyme defect or a mutation in the mitochondrial DNA (mtDNA). The provision of accurate genetic counseling and reproductive options to these families is complicated by the unique genetic features of mtDNA that distinguish it from Mendelian genetics. These include maternal inheritance, heteroplasmy, the threshold effect, the mitochondrial bottleneck, tissue variation, and selection. Although we still have much to learn about mtDNA genetics, it is now possible to provide useful guidance to families with an mtDNA mutation or a respiratory chain enzyme defect. We describe a range of current reproductive options that may be considered for prevention of transmission of mtDNA mutations, including the use of donor oocytes, prenatal diagnosis (by chorionic villus sampling or amniocentesis), and preimplantation genetic diagnosis, plus possible future options such as nuclear transfer and cytoplasmic transfer. For common mtDNA mutations associated with mitochondrial cytopathies (such as NARP, Leigh Disease, MELAS, MERRF, Leber's Hereditary Optic Neuropathy, CPEO, Kearns‐Sayre syndrome, and Pearson syndrome), we summarize the available data on recurrence risk and discuss the relative advantages and disadvantages of reproductive options. © 2001 Wiley‐Liss, Inc.
Advances in the genetics of progressive myoclonus epilepsy
Authors: Delgado‐Escueta A.V. , Ganesh Subramaniam , Yamakawa Kazuhiro
Published: October 2002

The genetic progressive myoclonus epilepsies (PMEs) are clinically characterized by the triad of stimulus sensitive myoclonus (segmental lightning like muscular jerks), epilepsy (grand mal and absences) and progressive neurologic deterioration (dementia, ataxia, and various neurologic signs depending on the cause). Etiologically heterogenous, PMEs are rare and mostly autosomal recessive disorders, with the exception of autosomal dominant dentatorubral‐pallidoluysian atrophy and mitochondrial encephalomyopathy with ragged red fibers (MERRF). In the last five years, specific mutations have been defined in Lafora disease (gene for laforin or dual specificity phosphatase in 6q24), Unverricht‐Lundborg disease (cystatin B in 21q22.3), Jansky‐Bielschowsky ceroid lipofuscinoses (CLN2 gene for tripeptidyl peptidase 1 in 11q15), Finnish variant of late infantile ceroid lipofuscinoses (CLN5 gene in 13q21‐32 encodes 407 amino acids with two transmembrane helices of unknown function), juvenile ceroid lipofuscinoses or Batten disease (CLN3 gene in 16p encodes 438 amino acid protein of unknown function), a subtype of Batten disease and infantile ceroid lipofuscinoses of the Haltia‐Santavuori type (both are caused by mutations in palmitoyl‐protein thiosterase gene at 1p32), dentadorubropallidoluysian atrophy (CAG repeats in a gene in 12p13.31) and the mitochondrial syndrome MERRF (tRNA Lys mutation in mitochondrial DNA). In this review, we cover mainly these rapid advances. © 2001 Wiley‐Liss, Inc.
Squirrel monkey chuck call: vocal response to playback chucks based on acoustic structure and affiliative relationship with the caller
Authors: Soltis Joseph , Bernhards Deborah , Donkin Hope , Newman John D.
Published: October 2002

Adult female squirrel monkeys (genus Saimiri) that are socially familiar often exchange the chuck vocalization, which differs acoustically across individuals. We used behavioral observations, vocalization playback experiments, and analysis of the acoustic properties of vocalizations to investigate the effect of caller identity and acoustic structure on vocal response to playback chucks in two all‐female social groups (n=10 females). Females were most likely to respond with a chuck to the playback chucks of their closely affiliated partners compared to those of nonaffiliated group members. This shows for the first time that the chuck stimulus alone is sufficient to elicit a chuck response from a female's affiliated partner. Additionally, females responded with a chuck mostly to familiar playback chucks from their own group and least to playbacks of silent controls. Unfamiliar playback chucks from the same species and a different squirrel monkey species elicited chuck responses intermediate between familiar chucks and silent controls. Post‐hoc discriminant function analyses provide preliminary evidence that females are most likely to respond to unfamiliar chucks when those chucks are close in acoustic structure to familiar chucks from their own social group. These results provide a provisional explanation for error in the squirrel monkey signal processing system, in which unfamiliar chucks never heard before nevertheless elicit a chuck response if they are similar in acoustic structure to familiar group chucks. © 2002 Wiley‐Liss, Inc.
Paraneoplastic chorea associated with CRMP‐5 neuronal antibody and lung carcinoma
Authors: Vernino Steven , Tuite Paul , Adler Charles H. , Meschia James F. , Boeve Bradley F. , Boasberg Peter , Parisi Joseph E. , Lennon Vanda A.
Published: October 2002

Paraneoplastic chorea is described in 16 patients: 11 with limited small‐cell carcinoma, 2 with lung cancer revealed by imaging, 1 with renal cell carcinoma, and 1 with lymphoma. All had CRMP‐5‐IgG; 6 also had ANNA‐1 (anti‐Hu), including 1 without evident cancer. Chorea was the initial and most prominent symptom in 11 patients, asymmetric or unilateral in 5 patients, and part of a multifocal syndrome in 14 patients. Basal ganglia abnormalities were revealed by magnetic resonance imaging and at autopsy (as perivascular inflammation and microglial activation). Four patients improved with chemotherapy, and 2 improved with intravenous methylprednisolone.
Effects of ovarian hormones on human cortical excitability
Authors: Smith Mark J. , Adams Linda F. , Schmidt Peter J. , Rubinow David R. , Wassermann Eric M.
Published: October 2002

Ovarian steroids appear to alter neuronal function in women, but direct physiological evidence is lacking. In animals, estradiol enhances excitatory neurotransmission. Progesterone‐derived neurosteroids increase GABAergic inhibition. The effect of weak transcranial magnetic stimulation of the motor cortex on the motor evoked potential (MEP) from transcranial magnetic stimulation given milliseconds later is changed by GABAergic and glutamatergic agents. Using this technique previously, we showed more inhibition in the luteal phase relative to the midfollicular menstrual phase, which is consistent with a progesterone effect. To detect the effects of estradiol, we have now divided the follicular phase. We tested 14 healthy women during the early follicular (low estradiol, low progesterone), late follicular (high estradiol, low progesterone), and luteal (high estradiol, high progesterone) phases, with interstimulus intervals from 2 to 10msec (10 trials at each interval and 40 unconditioned trials). We calculated the ratio of the conditioned MEP at each interval to the mean unconditioned MEP: the higher the ratio, the less inhibition and the more facilitation caused by the first stimulus. The combined ratios increased significantly from the early follicular phase to the late follicular phase and then decreased again in the luteal phase. These findings demonstrate an excitatory neuronal effect associated with estradiol and confirm our earlier finding of inhibition associated with progesterone.
Germline mosaicism of a novel mutation in lysosome‐associated membrane protein‐2 deficiency (Danon disease)
Authors: Takahashi Maki , Yamamoto Ayaka , Takano Kyoko , Sudo Akira , Wada Takahito , Goto Yu‐Ichi , Nishino Ichizo , Saitoh Shinji
Published: October 2002

We identified a family with lysosome‐associated membrane protein‐2 deficiency (Danon disease) associated with a novel 883 ins‐T mutation in the lysosome‐associated membrane protein‐2 gene located at Xq24. Although the affected son and daughter carried the same mutation, it was not detected in their mother's peripheral blood or buccal cells; this indicated germline mosaicism. This is the first molecular evidence for germline mosaicism in Danon disease and has important implications for genetic counseling.
Working memory after traumatic brain injury in children
Authors: Levin Harvey S. , Hanten Gerri , Chang Chung‐Chi , Zhang Lifang , Schachar Russell , Ewing‐Cobbs Linda , Max Jeffrey E.
Published: October 2002

To investigate the effects of traumatic brain injury on working memory in children, we administered semantic (letter identity) and phonological (letter rhyme) N‐back tasks to children who were on average 5 years post‐mild (n = 54) or ‐severe (n = 26) traumatic brain injury and 44 typically developing children who were comparable in age. The correct detection of targets and false alarms were measured for each task. Memory load (which varied from 0 to 3 letters back) and age significantly affected the detection of targets and false alarms in both tasks. The severity of traumatic brain injury affected the correct detection of letters on the identity task and false alarms on the rhyme task. Traumatic brain injury severity also interacted with memory load in its effect on false alarms on the rhyme task. Traumatic brain injury results in impaired working memory and diminished inhibition in children. The N‐back working memory task is feasible for administration to brain‐injured children and potentially could be useful for studying brain activation associated with working memory and effects of drug therapy in this group of patients.
Human antibodies against amyloid β peptide: A potential treatment for Alzheimer's disease
Authors: Dodel Richard , Hampel Harald , Depboylu Candan , Lin Suizhen , Gao Feng , Schock Sabine , Jäckel Steffi , Wei Xing , Buerger Katharina , Höft Christine , Hemmer Bernhard , Möller Hans‐Jürgen , Farlow Martin , Oertel Wolfgang H. , Sommer Norbert , Du Yansheng
Published: October 2002

Naturally occurring antibodies directed against β‐amyloid (Aβ) were detected in intravenous immunoglobulin preparations. After intravenous immunoglobulin treatment in patients with different neurological diseases, total Aβ and Aβ1‐42 in the cerebrospinal fluid was reduced significantly compared with baseline values. In the serum, total Aβ levels increased after intravenous immunoglobulin treatment, whereas no significant change was observed in Aβ1‐42 levels. Antibodies against Aβ were found to be increased in the serum and cerebrospinal fluid after intravenous immunoglobulin treatment. This study provides evidence that intravenous immunoglobulin or purified Aβ antibodies may modify Aβ and Aβ1‐42 levels, suggesting potential utility as a therapy for Alzheimer disease.
Dyskinesias and grip control in Parkinson's disease are normalized by chronic stimulation of the subthalamic nucleus
Authors: Wenzelburger Roland , Zhang Bao‐Rong , Poepping Meike , Schrader Bettina , Müller Dieter , Kopper Florian , Fietzek Urban , Mehdorn Hubertus M. , Deuschl Günther , Krack Paul
Published: October 2002

Deep‐brain stimulation of the subthalamic nucleus appears to reduce levodopa‐induced dyskinesias, but whether this effect is caused by the reduction of the total levodopa ingestion or represents a direct effect on the motor system is unknown. Precision grip force of grasping movements and levodopa‐induced dyskinesias was analyzed in 10 parkinsonian patients before and after 3 months of deep‐brain stimulation of the subthalamic nucleus. Peak grip force was abnormally increased before surgery in the off‐drug state and, particularly, in the on‐drug state (sensitization). This grip force upregulation normalized with chronic deep‐brain stimulation in both conditions (desensitization). Peak‐dose dyskinesias also improved, and off‐dystonia was completely abolished. Mean dosage of dopaminergic drugs was reduced, but force overflow and dyskinesias were equally improved in 2 patients without a reduction. Despite the same single levodopa test dose, force excess and levodopa‐induced dyskinesias were drastically reduced after 3 months of deep‐brain stimulation of the subthalamic nucleus. This indicates that direct effects of deep‐brain stimulation of the subthalamic nucleus on levodopa‐induced dyskinesias are likely to occur. Grip force overflow is a promising parameter to study the desensitizing effect of chronic deep‐brain stimulation on levodopa‐induced dyskinesias.
Preparation of water‐soluble chitosan derivatives and their antibacterial activity
Authors: Xie Wenming , Xu Peixin , Wang Wei , Liu Qing
Published: October 2002

Carboxymethyl chitosan sodium (CMCTS) was synthesized by chitosan and chloroacetic acid under an alkali catalyst. Acrylic acid sodium salt and methylacrylic acid sodium salt were grafted onto CMCTS to obtain copolymers with good water solubility. The graft reaction was carried out at 70°C for 2 h, and ammonium persulfate was used as an initiator. The structure changes of chitosan and its derivatives were investigated by the FTIR. The antibacterial activity of chitosan derivatives against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1357–1361, 2002
Melt strength of linear low‐density polyethylene/low‐density polyethylene blends
Authors: Ho Kam , Kale Larry , Montgomery Scott
Published: October 2002

Linear low‐density polyethylenes and low‐density polyethylenes of various compositions were melt‐blended with a batch mixer. The blends were characterized by their melt strengths and other rheological properties. A simple method for measuring melt strength is presented. The melt strength of a blend may vary according to the additive rule or deviate from the additive rule by showing a synergistic or antagonistic effect. This article reports our investigation of the parameters controlling variations of the melt strength of a blend. The reciprocal of the melt strength of a blend correlates well with the reciprocal of the zero‐shear viscosity and the reciprocal of the relaxation time of the melt. An empirical equation relating the maximum increment (or decrement) of the melt strength to the melt indices of the blend components is proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1408–1418, 2002
Preparation of soluble poly(amide imide) derivatives with metal salts and phosphorous compounds
Authors: Jeon Jong‐Young
Published: October 2002

Soluble poly(amide imide) derivatives were prepared through the direct polycondensation of 1,2,4‐benzenetricarboxylic acid and three diamines—bis[4‐(3‐aminophenoxy)phenyl]sulfone, bis(4‐aminophenyl)‐1,4‐diisopropylbenzene, and 4,4′‐oxydianilne—in the presence of metal salts and phosphorous compounds. Phosphonium salt, which was used as the initiating species and was prepared by the reaction of the metal salts and phosphorous compounds, reacted with 1,2,4‐benzenetricarboxylic acid to form acyloxy phosphonium salt, and then the salt was reacted with a diamine for the preparation of the prepolymers. The prepolymers were converted into the corresponding poly(amide imide)s in a homogeneous solution state at 180°C. The poly(amide imide)s showed good thermal and mechanical properties. Glass‐transition temperatures were observed from 240 to 270°C in differential scanning calorimetry traces. A melting endotherm was not observed for the polymers with differential scanning calorimetry. The initial decomposition occurred around 400°C according to thermogravimetric analysis, and major weight loss was observed from 610 to 680°C. The poly(amide imide)s had comparatively good solubility in aprotic polar solvents at concentrations high enough (∼30%) for the fabrication of various forms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1399–1407, 2002
Electromagnetic interference shielding effectiveness and mechanical sliding behavior for electroless nickel/phosphorous–poly(tetrafluoroethylene) codeposition on carbon fiber/acrylonitrile–butadiene–styrene composites
Authors: Huang Chi‐Yuan , Mo Wen‐Wei
Published: October 2002

Poly(tetrafluoroethylene) (PTFE) powders were mounted on an electroless nickel/phosphorous (Ni/P) film on the surface of a carbon fiber by an electroless codeposition method. This type of carbon fiber filler, denoted FENCF, was then compounded with acrylonitrile–butadiene–styrene (ABS) for use in electromagnetic interference shielding. For the suspension of the PTFE powders, a surfactant was used. Although the adhesion between the electroless Ni/P–PTFE films and the fiber was reduced, the PTFE powders on the surface of FENCF reduced the torque values when compounded into the ABS matrix because of a self‐lubricating effect. The two‐step FENCF composites exhibited particularly significant advantages. The torque values for the two‐step FENCF/ABS composites were about one‐half of those for carbon fiber/ABS composites in compounding processes; in addition, the former had an average mean fiber length almost 2.5 times that of the latter. The multiyield phenomena in stress–strain curves of FENCF/ABS composites implied that the PTFE powders mounted on Ni/P films slid during stress–strain action. The electromagnetic interference shielding effectiveness of FENCF/ABS composites did not decrease significantly even though the PTFE powders formed a discontinuous phase on the electroless Ni/P films. The mechanical properties of FENCF composites were enhanced because of the larger fiber length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1661–1668, 2002
Infrared spectra of γ‐irradiated poly(acrylic acid)–polyacrylamide complex
Authors: Moharram M. A. , Rabie S. M. , El‐Gendy H. M.
Published: October 2002

Samples of polyacrylamide (PAAm), poly(acrylic acid) (PAA), and their complex were γ‐irradiated at different doses, namely 48, 96, and 144 KGy. The examination of the infrared spectra of these samples showed that there are no significant observable changes in their spectral features apart from slight changes in the intensities of the absorption bands. The analysis of the absorbances ratios (A 1700 cm−1/A 1450 cm−1) and (A 1650 cm−1/A 1450 cm−1), denoted as R1 and R2, respectively, showed that these ratios depend on γ‐doses. It was found that in the case of PAA, R1 assumed linear increase with increasing the dose to 96 KGy and then showed marked decrease. For the complex, R1 increased slightly by increasing the dose to 96 KGy and then decreased. For PAAm, although irradiation with 48 KGy increases the values of R2, irradiation with 96 and 144 KGy decreases its value. On the other hand, for the complex, R2 suggested slight decrease on irradiation with 48 KGy followed by continued increases with increasing the dose up to 144 KGy. The increase in R1 and R2 may be due to crosslinking as a result of the formation of free radicals. The decrease in these ratios after irradiation with 96 KGy may be due to degradation. It was concluded that γ‐irradiation has a lower effect on the complex (i.e., the complex has a structure which is different from those of PAA and PAAm). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1619–1623, 2002
Thermal characteristics of IPNs composed of polyallylamine and chitosan
Authors: Kim Seon Jeong , Park Sang Jun , Shin Mi‐Seon , Lee Yong Hee , Kim Nam Gyun , Kim Sun I.
Published: October 2002

Interpenetrating polymer network (IPN) hydrogels composed of polyallylamine and chitosan were synthesized by radical polymerization using 2,2‐dimethyl‐2‐ phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The IPNs thus obtained were characterized by using Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). The melting temperatures of IPNs were observed with increasing chitosan content by DSC. DEA was employed to ascertain the glass transition temperature (Tg) of IPNs. From the result of DEA, IPNs exhibited two Tgs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated by TGA and appeared at near 270 °C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1956–1960, 2002
Characterization of biaxially oriented polypropylene films by atomic force microscopy and microthermal analysis
Authors: Abad M. J. , Ares A. , Barral L. , Cano J. , Díez F. J. , López J. , Ramírez C.
Published: October 2002

A new method for evaluating the thermal properties of the films and detecting fabrication failures has been provided. Moreover, this article studies the characterization of biaxially oriented polypropylene films (BOPP) using the Microthermal Analizer (μTA 2990). This instrument combines high‐resolution imaging capabilities of the atomic force microscopy (AFM) with physical characterization by thermal analysis. In the first part of the work, topographic images of the film surfaces were obtained by AFM. They showed that the fabrication process and additives to the films caused differences in the sample topography. In the second part, the thermal conductivity images of multilayer films were obtained by thermal analysis mode. The thickness of each layer was determined for several BOPP films, based on the thermal conductivity signal registered by μTA 2990. Finally, it has been proven that this new technique is valid for detection of thermal transitions in polymer samples. Thus, melting points and glass transitions were measured in the samples with thermal probe. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1553–1561, 2002.
The oxidative degradation of styrenic copolymers: A comparison of photoproducts formation under natural and accelerated conditions
Authors: Singh R. P. , Vishwa Prasad A. , Solanky S. S.
Published: October 2002

Natural and accelerated weathering of polystyrene and high‐impact polystyrene were carried out in the present investigation. The structural changes in the polymer samples were characterized by using FTIR spectroscopy, tensile strength testing, and SEM spectroscopy. The natural exposure was conducted throughout the year. Rates of photooxidation were determined by measuring the evaluation in hydroxyl and carbonyl regions. The surface deterioration was revealed from SEM micrographs. The drop in tensile strength was also monitored. A correlation between natural and artificial weathering was considered for lifetime prediction in a short exposure time. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1676–1682, 2002
Graft reaction of acrylic acid onto metallocene‐based polyethylene‐octene elastomer
Authors: Wu Chin‐San , Lai Sun‐Mou , Liao Hsin‐Tzu
Published: October 2002

In this study, grafting of acrylic acid (AA) onto metallocene‐based polyethylene‐octene elastomer (POE) was investigated by using benzoyl peroxide as an initiator. Grafted product was characterized by using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X‐ray diffraction spectroscopy, and differential scanning calorimetry (DSC). Both the grafting percentage and the gel yield, at equilibrium, were higher for POE containing lower degree of comonomer content. In all cases, the crosslinking reaction was accompanied by the predominant graft reaction due to the competition of POE macroradical and excited AA. From the result of DSC and X‐ray characterizations, it was found that the change of crystallinity is slight when the gel is removed from POE‐g‐AA copolymers. It was also proven that the effect of gel formation on the properties of the copolymer could be neglected because of the low gel yield. So, the graft method proposed in this article can produce low gel yield copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2905–2912, 2002
Poly(L‐lactide). IX. Hydrolysis in acid media
Authors: Tsuji Hideto , Nakahara Kazumasa
Published: October 2002

Amorphous and crystallized poly(L‐lactide) (PLLA) films are prepared by quenching and annealing at 140°C for 600 min, respectively, from the melt. Their hydrolysis is investigated at pH 2.0 in HCl and DL‐lactic acid (DLLA) solutions (37°C) for up to 300 days, and the results are compared with those obtained for PLLA films hydrolyzed at pH 7.4 (phosphate‐buffered solution) and pH 12 (NaOH solution). The changes in the weight loss and molecular weight distribution of the PLLA films during hydrolysis in the acid media reveals that their hydrolysis proceeds homogeneously along the film cross section by mainly a bulk erosion mechanism. Moreover, the durability of PLLA films in the acid media is very similar to that in the neutral medium but higher than that in the alkaline medium. The hydrolysis rate constant values (k) of the initially amorphous PLLA0 film evaluated from the changes in the number‐average molecular weight were 3.0 and 2.4 × 10−3 day−1 at pH 2.0 in the HCl and DLLA solutions, respectively. These k values are very similar to 2.6 × 10−3 day−1 at pH 7.4 in the phosphate‐buffered solution. The similar k values and the negligible weight loss after the hydrolysis for 300 days reflect that the hydronium ions and the lactic acid oligomers and monomers have insignificant catalytic effects on the hydrolysis of the PLLA films. Increasing the initial crystallinity of the PLLA film increases the hydrolysis rate in the HCl solution, whereas increasing the initial crystallinity of the PLLA film does not alter the hydrolysis rate in the DLLA solution. The differential scanning calorimetry results show that the crystallization of PLLA chains occurs during the hydrolysis, irrespective of the hydrolysis acid media and the initial crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 186–194, 2002
Ultrasonic improvement of the compatibility and rheological behavior of high‐density polyethylene/polystyrene blends
Authors: Chen Guangshun , Guo Shaoyun , Li Huilin
Published: October 2002

The effects of ultrasonic oscillations on the rheological behavior, mechanical properties, and morphology of high‐density polyethylene (HDPE)/polystyrene (PS) blends were studied. The experimental results show that the die pressure and apparent viscosity of HDPE/PS blends are remarkably reduced in the presence of ultrasonic oscillations and that mechanical properties of the blends are improved. The particle size of the dispersed phase in HDPE/PS blends becomes smaller, its distribution becomes narrower, and the interfacial interaction of the blends becomes stronger if the blends are extruded in the presence of ultrasonic oscillations. Ultraviolet spectra and Soxhlet extraction results show the formation of a polyethylene‐PS copolymer during extrusion in the presence of ultrasonic oscillations, which improves the compatibility of HDPE/PS blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 23–32, 2002
Surface modification of polymethyl methacrylate intraocular lenses with the mixture of acrylic acid and acrylamide via plasma‐induced graft copolymerization
Authors: Suh Tae Suk , Joo Choun‐Ki , Kim Young Chai , Lee Moo Suk , Lee Hyoung Koo , Choe Bo Young , Chun Heung Jae
Published: October 2002

An approach is presented for the graft copolymerization of acrylic acid (AAc) and acrylamide (AAm) mixture onto the surfaces of polymethyl methacrylate intraocular lenses (PMMA IOLs) treated with an Argon gas plasma, followed by the exposure to the oxygen atmosphere. In this case, peroxides formed by the plasma treatment are likely to be responsible for initiating the graft copolymerization. The amount of peroxides on the surface of PMMA IOLs was determined using 1,1‐diphenyl‐2‐picrylhydrazyl, and the maximum amount was found with the plasma treatment at 30 W for 20 s under 5 mTorr pressure. The surfaces of the grafted PMMA IOLs were characterized using Fourier transform infrared spectroscopy‐attenuated total reflectance (FTIR‐ATR), electron spectroscopy for chemical analysis, and contact angle meter. The FTIR‐ATR spectrum of PMMA‐g‐AAc‐AAm showed the characteristic band of PAAc at 1580 cm−1 together with those of PAAm at 1670 and 1630 cm−1, confirming that the copolymer of AAc and AAm was successfully grafted onto the surfaces of PMMA IOLs. The experimental data of O1s/C1s and N1s/C1s reasonably concurred with the calculated data, a strong indication that the pH value of the reaction medium at 3.77 could produce a graft with an equal molar ratio. Surface tension of the samples increased to 52 dyn/cm due to the graft of the hydrophilic monomers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2361–2366, 2002
Enhancement of processability of cyanate ester resin via copolymerization with epoxy resin
Authors: Liang Guozheng , Zhang Mingxi
Published: October 2002

Two new matrices with enhanced processing characteristics, made from bisphenol A cyanate ester (BCE) and diglycidyl ether of bisphenol A epoxy resin or o‐cresol formaldehyde novolac epoxy resin, were developed. Solubility, differential scanning calorimetry (DSC), gel time, and tack experiments were used to detect the processing characteristics of the two new systems and neat BCE. Results show that the two new systems have enhanced processability compared with neat BCE, especially improved tack and drape properties of prepregs, and faster thermal polymerization rate. In addition, the two new cured systems have more than two times improved impact strength without a great decrease in excellent dielectric properties or thermal and hot–wet resistance of neat BCE resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2377–2381, 2002
Free radical oxidative copolymerization of indene with vinyl acetate and isopropenyl acetate: Synthesis and characterization
Authors: De Priyadarsi , Sathyanarayana D. N.
Published: October 2002

Copolyperoxides of different compositions of indene with vinyl acetate and isopropenyl acetate were synthesized by the free radical‐initiated oxidative copolymerization. The compositions of copolyperoxides obtained from 1H‐ and 13C‐NMR spectra have been used to determine the reactivity ratio of the monomers. The reactivity ratios reveal that the copolyperoxides contain a larger proportion of the indene units in random placement. The NMR studies further suggest irregularities in the copolyperoxide chain possibly due to the cleavage reactions of the propagating peroxide radical. The thermal analysis by differential scanning calorimetry (DSC) supports the alternating peroxide units in the copolymer chain. The activation energy for the thermal degradation suggests that the degradation is dependent on the dissociation of the peroxide (OO) bonds in the copolyperoxide chain. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86:639–646, 2002
Use of novel hydrogels based on modified cellulosics and methacrylamide for separation of metal ions from water systems
Authors: Chauhan Ghanshyam S. , Mahajan Swati
Published: October 2002

Interpenetrating networks (IPNs) based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), cyanoethylcellulose, hydroxyethylcellulose, hydrazinodeoxycellulose, cellulosephosphate with methacrylamide (MAAm), and N,N‐methylene bisacrylamide were synthesized at reaction conditions evaluated for optimum network yield as a function of irradiation dose, concentrations of monomer and crosslinker, and amount of water. These networks were used in sorption of Fe2+, Cu2+, and Cr6+ ions. The networks were further functionlized by means of partial hydrolysis with 0.5N NaOH and metal ion sorption studies were carried out. Appreciable amount of all the three ions was sorbed and partial functionalization of the hydrogels results in selectivity in ion sorption with enhanced affinity for Fe2+ ions and total rejection of Cr6+ ions. These results are of interest for the development of low‐cost technologies based on smart hydrogels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 667–671, 2002
Photoreactivity of vinyl ether/oxirane‐based resin systems
Authors: Chappelow C. C. , Pinzino C. S. , Power M. D. , Holder A. J. , Morrill J. A. , Jeang L. , Eick J. D.
Published: October 2002

We evaluated the reactivity in homopolymerization and as comonomers in dioxirane/polyol visible‐light curable systems the following vinyl ethers (VEs): mono‐, di‐, and tri(ethylene glycol) divinyl ethers (EGDVE, DEGDVE, and TEGDVE, respectively); 1,6‐hexanediol divinyl ether (HDDVE); cyclohexanedimethanol divinyl ether (CHDMDVE); glycidyl vinyl ether (GVE); 4‐(1‐propenyloxymethyl)‐1,3‐dioxolan‐2‐one (POMDO); and 1,4‐butanediol vinyl ether (BDVE). The dioxirane/polyols (80/20) were Cyracure UVR 6105 or ERL 4206 dioxiranes with polytetrahydrofuran [PTHF; number‐average molecular weight (Mn) = 250]. Reactivities were evaluated by photodifferential scanning calorimetry with visible light. For VE homopolymerization, the relative reactivity ranking (based on exotherm peak maximum time) was TEGDVE > EGDVE > DEGDVE > HDDVE > CHDMDVE > BDVE > GVE ≫ POMDO. For VEs in UVR 6105/PTHF, the ranking was GVE > TEGDVE > CHDMDVE > BDVE > EGDVE ≫ DEGDVE = HDDVE = POMDO. In ERL 4206/PTHF, the ranking was: GVE > TEGDVE > BDVE > DEGDVE ≫ HDDVE > EDGDVE ≫ CHDMDVE = POMDO. The incorporation of an electron‐donating reaction promoter, ethyl‐4‐dimethylaminobenzoate, generally shortened induction times and exotherm peak maximum times and increased rate constants for homopolymerizations and ternary polymerizations. Experimentally determined polymerization reactivities were compared with previously reported semiempirical quantum mechanical calculations of activation energies and heats of reaction. The results of laboratory and computational studies for selected compounds were in general agreement. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 314–326, 2002
Polyphosphazene/low‐density polyethylene blends: Miscibility and flame‐retardance studies
Authors: Chen Donghua , Cui Yanjun , Wang Xinlin , Tang Xiaozhen
Published: October 2002

The effect of poly(dianilinephosphazene) (PDAP) on the processability, thermal behavior, crystallinity, morphology, mechanical properties, and flammability behavior of low‐density polyethylene (LDPE) was studied. Plasticorder traces of PDAP/LDPE blends implied good processability and miscibility. Thermogravimetric analysis showed that PDAP improved the thermal stability of LDPE. X‐ray diffraction results indicated that PDAP was a semicrystalline polymer, and the crystallinity of the blends decreased with increasing PDAP content. A new reflection at 2θ = 23.15° was found in wide‐angle X‐ray diffraction spectra of the blends, indicating that these two components interacted with one another. The scanning electron microscopy microstructures of the blends also supported these findings. Moreover, PDAP substantially enhanced the limited oxygen index and elongation at break of LDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 709–714, 2002
Thermal analysis of high‐density polyethylene and low‐density polyethylene with enhanced biodegradability
Authors: Contat‐Rodrigo L. , Ribes‐Greus A. , Imrie C. T.
Published: October 2002

The thermal properties of high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) filled with different biodegradable additives (Mater‐Bi AF05H, Cornplast, and Bioefect 72000) were investigated with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The DSC traces of the additives indicated that they did not undergo any significant phase change or transition in the temperature region typically encountered by a commercial composting system. The TGA results showed that the presence of the additive led to a thermally less stable matrix and higher residue percentages. The products obtained during the thermodegradation of these degradable polyolefins were similar to those from pure polyethylenes. The LDPE blends were thermally less stable than the HDPE blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 764–772, 2002
Thermal aging of undoped polyaniline: Effect of chemical degradation on electrical properties
Authors: Kieffel Yannick , Travers Jean Pierre , Ermolieff Anne , Rouchon Denis
Published: October 2002

Aging experiments, with a special emphasis on the atmosphere effect, have been carried out on undoped polyaniline, in its half‐oxidized state, namely emeraldine base (EB). The polymer has been aged under vacuum and in air atmosphere. The chemical degradation has been analyzed by several complementary techniques such as viscosity measurements, FTIR, XPS, and UV‐Vis‐nIR spectroscopy. We show that emeraldine base exhibits two different degradation mechanisms. The first one is intrinsic to the polymer and occurs independently on aging conditions (vacuum or air). It consists of crosslinking via tertiary amine groups created from imine nitrogen via double‐bond breaking. The second mechanism is extrinsic and occurs concomitantly with the first one upon aging in air. It consists of oxygen incorporation in a form of carbonyl groups and chain scission. Both degradation pathways result in a decrease of the electrical conductivity of the polymer due to the lowering of the average conjugation length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 395–404, 2002
Extrudate swell and texture of PS, LDPE, ABS, PVC melts and their blends in extrusion capillary flow using a magnetic die
Authors: Sombatsompop N.
Published: October 2002

The extrudate swell behavior and extrudate texture of various thermoplastic melts, namely, polystyrene (PS), low‐density polyethylene (LDPE), acrylonitrile‐butadiene styrene (ABS) copolymer, poly(vinyl chloride) (PVC), and their blends, were examined weith a magnetic die system in a constant‐shear‐rate capillary rheometer at a shear rate range 5–28 s−1 and a temperature range 170–230 °C. The extrudate swell results obtained from the magnetic die were then compared with those produced by a nonmagnetic die. The results showed that the extrudate swell increased with shear rate, but decreased with temperature. In a pure polymer system, up to 25% increase in the extrudate swell was observed with the application of the magnetic field to the PS melt, and the effect decreased in the order ABS > LDPE > PVC. The extrudate swell changes were associated with the changes in rheological properties of the melts. The extrudate textures of the ABS and PVC melts were improved by the magnetic field. In PS/LDPE or PS/ABS blend, it was found that the magnetic die resulted in higher values of the extrudate swell than the nonmagnetic die for all blends, the magnetic effect being less as the LDPE or ABS content was increased. For PS/LDPE system, the extrudate swell of the PS melt did not change much with addition of 20% LDPE, but slightly decreased at the LDPE loading of 40%. At higher LDPE loadings, the extrudate swell increased towards the value of the pure LDPE melt. For PS/ABS system, the extrudate swell ratio progressively decreased with increasing ABS content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 509–517, 2002