bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Method for the Synthesis of Highly Oriented Potassium‐Doped Tungsten Oxide Nanowires
Authors: Qi H. , Wang C. , Liu J.
Published: March 2003

Very long and highly oriented potassium‐doped tungsten oxide nanowires (see Figure) can be synthesized using the simple technique presented here. The mechanism of nanowire formation is investigated and a vapor–liquid–solid mechanism is proposed. This novel method can be easily scaled up and can also be extended to the preparation of nanowire arrays of other materials.
Sol–Gel Electrophoretic Deposition for the Growth of Oxide Nanorods
Authors: Limmer S.J. , Cao G.
Published: March 2003

By combining sol–gel processing with electrophoretic deposition, we have developed a new method for the growth of oxide nanorods. Both single metal oxides (TiO2, SiO2) and complex oxides—BaTiO3, Sr2Nb2O7, and Pb(Zr0.52Ti0.48)O3—have been grown by this method. Uniformly sized nanorods 45–200 nm in diameter and 10 μm in length can be grown over large areas with near unidirectional alignment. The nanorods have the desired stoichiometric chemical composition and crystal structure, after firing to 500–700 °C for up to one hour.
Anisotropic Shape Control of Colloidal Inorganic Nanocrystals
Authors: Lee S.‐M. , Cho S.‐N. , Cheon J.
Published: March 2003

The systematic shape control of colloidal nanocrystals including one‐dimensional (1D) nanorods remains a key issue in the “bottom–up” approach of nanoscience. Here, we examine the anisotropic structural evolution of various semiconductor nanocrystals and systematically elucidate the key growth parameters for their shape control. The crystalline phase of nucleating seeds and kinetic growth regimes controlled by changing growth parameters are crucial for the determination of the 1D nanocrystal geometry.
Template‐Fabricated Gold Nanowires and Nanotubes
Authors: Wirtz M. , Martin C.R.
Published: March 2003

Gold nanowires and nanotubes are prepared via electroless deposition of Au onto the pore walls of a porous polymeric membrane. The pores in the support membrane act as a template for the nanostructures. The support is a commercially available nanoporous polycarbonate filter with cylindrical nanoscopic pores. We have shown that by controlling the Au deposition time, Au nanotubes (short deposition times) or nanowires (longer deposition times) can be prepared. The gold nanowires and nanotube membranes can be utilized for nanoelectrode ensembles, molecular filters and as chemical switches.
High serum transferrin receptor level in anemia of chronic disorders indicates coexistent iron deficiency
Authors: Das Gupta Amar , Abbi Alpana
Published: March 2003

Blood transferrin receptor (TR) level is largely determined by the quantum of erythropoiesis and by intracellular iron content of the cells of the erythroid lineage. Hence, a high serum TR level has been found to be useful in distinguishing iron deficiency anemia (IDA) from anemia of chronic disorders (ACD). In order to examine its potential role in the diagnosis of concomitant iron deficiency in ACD, we determined serum TR levels in 130 cases of ACD, in 25 cases of IDA, and in 40 normal adults. As expected, all patients of IDA had significantly higher serum TR levels compared to the normal subjects (4.2–19.2 μg/dL vs. 1.3–3.0 μg/dL) (P < 0.002). In 11/25 cases of IDA, the total iron‐binding capacity (TIBC) was in the normal range although bone marrow iron store was absent and serum TR levels were high, thereby highlighting the superiority of TR level in the diagnosis of iron deficiency compared to TIBC. Although 54% (70/130) patients of ACD had normal or low serum TR levels (0.9–3.0 μg/dL) as expected, in 46% (60/130) of ACD patients, serum TR levels were high (3.2–11.0 μg/dL). Mean corpuscular volume, red cell distribution width, and transferrin saturation were significantly lower (P < 0.001) in the latter group of patients compared to the former, and these parameters resembled those in IDA patients. Also, serum iron was lower and TIBC was higher in this group of ACD patients compared to those with normal or low serum TR. All these features point to an “IDA‐like” profile of ACD patients with high TR and support the possibility of co‐existent iron deficiency in this subgroup of ACD patients. In light of these observations it would be prudent to treat ACD patients with high serum TR levels with iron replacement therapy. Am. J. Hematol. 72:158–161, 2003. © 2003 Wiley‐Liss, Inc.
Use of plasma exchange in methotrexate removal in a patient with osteosarcoma and acute renal insufficiency
Authors: Cecyn Karin Zattar , Lee Juno , Oguro Tsutomo , Petrilli Antônio Sérgio , Bordin José Orlando
Published: March 2003

Acute renal failure induced by methotrexate (MTX) can be lethal because renal excretion of the drug can be delayed. Pre‐existing renal impairment, abstention, or underdosage of folinic acid and inadequate hydration facilitate toxicity. The prolonged high serum levels of MTX result in severe mucositis and pancytopenia, but strategies useful to accelerate MTX removal have not been universally accepted. We report a case of a 13‐year‐old girl with osteosarcoma who was treated with high‐dose MTX because of thoracic tumor recurrence. No side effects were observed after 2 cycles of high‐dose MTX; however, after the third cycle there was a delayed MTX elimination followed by clinical toxicity. Forty hours post‐MTX infusion the serum level of MTX was 5.39 × 10−4 mol/L. Treatment was based on symptomatic measures, such as maintenance of an abundant and alkaline diuresis and parenteral administration of folinic acid. Concomitantly, plasma exchange was employed to accelerate MTX removal and reduce its toxicity. After 24 days, she was discharged from the hospital, and her renal function recovered gradually. Am. J. Hematol. 72:209–211, 2003. © 2003 Wiley‐Liss, Inc.
Decreased exhaled nitric oxide in sickle cell disease: Relationship with chronic lung involvement
Authors: Girgis Reda E. , Qureshi Mohammed A. , Abrams Judith , Swerdlow Paul
Published: March 2003

A deficiency in airway nitric oxide (NO) could contribute to pulmonary vaso‐occlusion in sickle cell disease (SCD). We measured the fractional expired concentration of NO (FENO) by chemiluminescence during a slow vital capacity maneuver against a positive pressure of 16 cm H2O at an expiratory flow rate of 50 mL/sec in 44 stable ambulatory adults with SCD and 30 healthy controls. A history of acute chest syndrome was present in 29 patients, and 22 complained of dyspnea. Mean ± SD FENO was significantly reduced in the SCD group compared with controls (14.8 ± 8.4 vs. 24.9 ± 13.5 ppb, P < 0.001). SCD patients with dyspnea had lower FENO than those without dyspnea (10.1 ± 5.7 vs. 19.6 ± 8 ppb, P < 0.001) and those with a history of ACS had lower values than those no episodes of ACS (13.0 ± 8.3 vs. 18.4 ± 7.6 ppb, P < 0.05). There was a weak correlation between FENO and percent‐predicted DLCO (r = 0.4, P = 0.02) among the SCD patients. We conclude that exhaled NO is reduced in adults with SCD, and this may play a role in the pathogenesis of acute chest syndrome and chronic sickle cell lung disease. Am. J. Hematol. 72:177–184, 2003. © 2003 Wiley‐Liss, Inc.
Reduced‐intensity bone marrow transplantation from an alternative unrelated donor for myelodysplastic syndrome of first‐donor origin
Authors: Komeno Yukiko , Kanda Yoshinobu , Kandabashi Koji , Kawazu Masahito , Goyama Susumu , Takeshita Masataka , Nannya Yasuhito , Niino Miyuki , Nakamoto Tetsuya , Kurokawa Mineo , Tsujino Shiho , Ogawa Seishi , Aoki Katsunori , Chiba Shigeru , Motokura Toru , Hirai Hisamaru
Published: March 2003

A male patient had a relapse of myelodysplastic syndrome (MDS) 2 years after BMT from a female matched unrelated donor. Conventional cytogenetics, FISH, and short‐tandem repeat chimerism analysis proved a relapse of donor origin. He underwent reduced‐intensity BMT after a conditioning with fludarabine and busulfan, since he had impaired renal, liver, and pulmonary functions. Chimerism analysis on day 28 after the second BMT showed mixed chimerism of the first and the second donors, which later turned to full second‐donor chimerism on day 60. He developed grade II acute GVHD of the skin and cytomegalovirus reactivation, but both were improved with methylprednisolone and ganciclovir, respectively. He remains in complete remission 6 months after the second BMT. Reduced‐intensity second BMT from an alternative donor appeared to be a tolerable treatment option for donor‐derived leukemia/MDS after the first conventional transplantation. Am. J. Hematol. 72:220–222, 2003. © 2003 Wiley‐Liss, Inc.
Simple fluorescent PCR method for detection of large deletions in the β‐globin gene cluster
Authors: De Andrade Tiago Gomes , Saad Sara Teresinha Olalla , de Fatima Sonati Maria , Costa Fernando Ferreira
Published: March 2003

We developed a semi‐automated approach to detect large deletions in the β‐globin gene cluster, based on the quantitative differences in the amplifications of samples by a fluorescent PCR. With this strategy, we were able to detect the presence of HPFH‐2 in an African‐Brazilian subject, confirmed by sequencing analysis. Differently from other PCR strategies, GAP‐PCR for example, it has the potential to identify new deletions. Am. J. Hematol. 72:225–227, 2003. © 2003 Wiley‐Liss, Inc.
Modeling growth and senescence in physical performance among the ache of eastern paraguay
Authors: Walker Robert , Hill Kim
Published: March 2003

This article seeks to partially fill a paucity of available data on physical performance in hunter–gatherer societies. Quantitative data are presented on various physical performance measures conducted on the Ache of eastern Paraguay, hunter–gatherers up to the 1970s and now part‐time foragers and horticulturists. The performance battery was conducted on most individuals over 10 years of age, allowing for cross‐sectional examination of growth and senescence patterns across the lifespan for both sexes. These measures tend to display steep ascents and peak in the early 20s with slight declines thereafter with age for males, whereas females demonstrate peaks in performance earlier in life, with lower or no senescence rates thereafter. The result is a convergence in physical performance between men and women at later ages. We suggest that the female physiology faces reproductive constraints to performance early in life but shifts allocation to increased work output later in life during the long human postmenopausal stage. In contrast, the male physiology maximizes work output in early adult life. These schedules of physical performance are contrasted with schedules of food production ability, which tend to occur later in life, and therefore imply that skill rather than strength alone is an important component of the human foraging niche. Am. J. Hum. Biol. 15:196–208, 2003. © 2003 Wiley‐Liss, Inc.
Leukodystrophy associated with oligodontia in a large inbred family: Fortuitous association or new entity?
Authors: Atrouni Salim , Darazé Antoine , Tamraz Jean , Cassia Antoine , Caillaud Catherine , Mégarbané André
Published: March 2003

We describe a large inbred Syrian pedigree with an autosomal recessive neurodegenerative disorder. The clinical picture of the affected patients is oligodontia, and a degenerative neurological condition with onset around age 12, characterized by progressive ataxia and pyramidal syndrome. Abnormalities in the white matter and cortical atrophy were assessed by magnetic resonance imaging. Differential diagnosis and the possibility of a fortuitous association or the report of a hitherto unreported dento‐leukoencephalopathy are discussed. © 2003 Wiley‐Liss, Inc.
X‐chromosome inactivation (XCI) patterns in placental tissues of a paternally derived bal t(X;20) case
Authors: Peñaherrera M.S. , Ma S. , Ho Yuen B. , Brown C.J. , Robinson W.P.
Published: March 2003

Non‐random X‐chromosome inactivation (XCI) is often seen in female carriers of balanced X‐autosome translocations and is generally attributed to a selective growth of cells that inactivate the normal X chromosome. However, little is known concerning when in development the selection acts, and thus whether skewed XCI would also be seen in placental tissues. Furthermore, as males with X‐autosome translocations are normally infertile, all translocations studied to date for XCI‐skewing have been either maternal or de novo in origin. We now present an analysis of XCI status in cord blood, umbilical cord and four different extraembryonic tissues from a female carrier of a paternally derived balanced (X;20) translocation. Using methylation based assays to determine XCI status, we found preferential inactivation of the non‐translocated X in cord blood, umbilical cord and amnion samples of the propositus. Remarkably, random XCI was evident in several placental tissues analyzed (chorion, and chorionic villi trophoblast and mesenchyme). While these findings support the hypothesis of strong selection against cells with an inactive translocated X‐chromosome in most embryonic/fetal tissues, they also suggest weaker selective forces taking place during placental development. Additionally, the finding of normal placental development in the present case, rules out the possibility of a parental bias to XCI in human extraembryonic tissues as a requisite for normal development. The finding of hypomethylation in extraembryonic tissues for two out of three markers used in the study is consistent with previous findings demonstrating low levels of methylation in these tissues. © 2003 Wiley‐Liss, Inc.
Complex chromosomal rearrangement and associated counseling issues in a family with Pelizaeus‐Merzbacher disease
Authors: Woodward Karen , Cundall Maria , Palmer Rodger , Surtees Robert , Winter Robin M. , Malcolm Sue
Published: March 2003

We report cytogenetic and molecular findings in a family in which Pelizaeus‐Merzbacher disease has arisen by a sub‐microscopic duplication of the proteolipid protein (PLP1) gene involving the insertion of ∼600 kb from Xq22 into Xq26.3. The duplication arose in an asymptomatic mother on a paternally derived X chromosome and was inherited by her son, the proband, who is affected with Pelizaeus‐Merzbacher disease. The mother also carries a large interstitial deletion of ∼70 Mb extending from Xq21.1 to Xq27.3, which is present in a mosaic form. In lymphocytes, the mother has no normal cells, having one population with three copies of the PLP1gene (one normal X and one duplication X chromosome) and the other population having only one copy of the PLP1 gene (one normal X and one deleted X chromosome). Her karyotype is 46,XX.ish dup (X) (Xpter → Xq26.3::Xq22 → Xq22::Xq26.3 → Xqter)(PLP++)/46,X,del(X)(q21.1q27.3).ish del(X)(q21.1q27.3)(PLP−). Both ends of the deletion have been mapped by fluorescence in situ hybridization using selected DNA clones and neither involves the PLP1 gene or are in the vicinity of the duplication breakpoints. Prenatal diagnosis was carried out in a recent pregnancy and the complex counseling issues associated with these chromosomal rearrangements are discussed. © 2003 Wiley‐Liss, Inc.
Cranio‐cerebello‐cardiac (3C) syndrome: Follow‐up study of the original patient
Authors: Zankl Andreas , Güngör Tayfun , Schinzel Albert
Published: March 2003

In 1987, Ritscher et al. described two sisters with brain malformations of the posterior fossa, congenital heart defects, and similar craniofacial dysmorphisms. Subsequently, more than 20 cases have been reported and the syndrome became known as 3C (cranio‐cerebello‐cardiac) or Ritscher‐Schinzel syndrome. The majority of patients were younger than six years of age at the time of observation. Here we present a follow‐up study of one of the two sisters described by Ritscher et al. in 1987. At 21 years of age she is the oldest patient reported to date. We delineate growth, intellectual development, and evolution of her congenital developmental defects. We also provide evidence that the originally reported immune deficiency in this patient is not a primary B‐cell defect but a secondary loss of IgG via the gastrointestinal system. © 2003 Wiley‐Liss, Inc.
Thanatophoric dysplasia type II with encephalocele and aortic hypoplasia diagnosed in an anatomical specimen
Authors: Jap‐A‐Joe Simone M.E.A.A. , Oostra Roelof‐Jan , Maas Mario , Stoker Jaap , van der Horst Chantal M.A.M.
Published: March 2003

A hitherto unknown combination of congenital anomalies was found in an anatomical specimen of a female neonate. External examination and additional CT and MRI studies showed thanatophoric dysplasia type II with cloverleaf skull and concomitant parietal meningoencephalocele and hypoplasia of the descending aorta. The possibilities of causal correlations are discussed. © 2003 Wiley‐Liss, Inc.
Shashi XLMR syndrome: Report of a second family
Authors: Castro Nelson H.C. , Stocco dos Santos Rita C. , Nelson Retecher , Beçak Willy , Hane Bernhard , Lindsey Charles J. , Lubs Herbert A. , Stevenson Roger E. , Schwartz Charles E.
Published: March 2003

This report describes a family with mental retardation in two brothers. The pedigree is consistent with either X‐linked mental retardation or autosomal recessive inheritance. The clinical features consist of coarse face, prominent lower lip, large testes, and obesity. This same constellation of findings was observed in a family with X‐linked mental retardation (XLMR) reported by Shashi et al. [2000: Am J Hum Genet 66:469–479]. Furthermore, haplotype analysis was consistent with localization of the Shashi XLMR syndrome in Xq26‐q27. Thus, the family likely represents a second occurrence of the Shashi XLMR syndrome. © 2003 Wiley‐Liss, Inc.
Association between the CCK‐A receptor gene and panic disorder
Authors: Ise Kiminobu , Akiyoshi Jotaro , Horinouchi Yukiko , Tsutsumi Takashi , Isogawa Koichi , Nagayama Haruo
Published: March 2003

Cholecystokinin (CCK) is one of the most abundant neurotransmitter peptides in the brain. CCK appears to play an important role in the neurobiology of anxiety and panic disorders (PD) in both humans and animals. Recently, we reported that lack of CCKAR had a significant anxiogenic‐like effect in rats. In this study, to investigate the role of CCKAR in PD, we compared the CCKAR gene in PD patients and normal controls. Subjects who fulfilled the DSM‐IV criteria for PD were 17 males and 26 females. The sequence containing the Pst I polymorphic site in the boundary between intron 1 and exon 2 of the CCKAR gene was studied. Pst I digestion of the PCR products gave two individual alleles: A1 and A2. The A1 allele was the undigested fragment and the A2 allele was the digested one with two variant bands at 264 and 180 bp. Genotypic frequencies were 20.9% (A1‐A1), 55.8% (A1‐A2), and 41.7% (A2‐A2) in patients, and 20.5% (A1‐A1), 46.2% (A1‐A2), and 33.3% (A2‐A2) in controls. Allelic frequencies were 48.8% (A1) and 51.2% (A2) in patients, and 43.6% (A1) and 56.4% (A2) in controls. The chi‐square test did not show a significant difference in either genotypic or allelic frequencies between patients and control subjects. The Pst polymorphism of CCKAR may not be associated with PD. © 2003 Wiley‐Liss, Inc.
Association between the cortisol response to opioid blockade and the Asn40Asp polymorphism at the μ‐opioid receptor locus (OPRM1)
Authors: Hernandez‐Avila Carlos A. , Wand Gary , Luo Xingguang , Gelernter Joel , Kranzler Henry R.
Published: March 2003

This study examined whether a reportedly functional polymorphism in the gene encoding the μ‐opioid receptor protein (A118G, which causes an Asn40Asp substitution in the receptor's extracellular domain), modifies the cortisol response to the opioid antagonist naloxone. The polymorphism occurs commonly in European Americans and some other population groups, underscoring its potential phenotypic significance. Methods: Using a balanced, within‐subject design involving two test sessions over a period of 3–7 days, we examined ACTH and cortisol responses to intravenous naloxone (125 μg/kg) or placebo in 30 healthy subjects (21 males, mean age = 24.4 years). Plasma ACTH and cortisol concentrations were measured over 120 min post infusion. DNA isolated from whole blood was PCR amplified and genotyped via restriction enzyme digestion, with genotypes assigned based on agarose gel size fractionation. Results: Subjects with one or more Asp40 alleles (n = 6; 5 heterozygotes and 1 homozygote) had significantly higher cortisol concentrations at baseline and at 15, 60, and 90 min after naloxone infusion than subjects homozygous for the Asn40 allele (n = 24). Subjects with the Asp40 allele also had a greater peak cortisol response and a greater area under the cortisol time curve than those homozygous for the Asn40 allele. There were no effects of the Asn40Asp polymorphism on plasma ACTH concentration or on self‐reported anxiety or distress. Conclusions: These findings are consistent with recent reports showing an enhanced cortisol response to naloxone and a reduced agonist effect of morphine‐6‐glucuronide among subjects with the Asp40 variant. Given evidence of its pharmacological significance, the clinical relevance of this polymorphism warrants further investigation. © 2003 Wiley‐Liss, Inc.
Colors of primate pelage and skin: Objective assessment of conspicuousness
Authors: Sumner Petroc , Mollon J.D.
Published: March 2003

We present a quantitative means of assessing the conspicuousness of animal coats or other objects in terms of the color vision of each possible observer. We measured reflectance spectra from the fur and skin of many primate species in order to provide an objective survey of the possibilities of pelage coloration found in extant primates. We show that the orange coloration displayed by many platyrrhine and some strepsirhine primates, while being conspicuous to humans, would be cryptic amongst foliage to all males and many females of their own species. In relation to this finding, we briefly review what is known of the color vision of birds that prey on primates, and assess how conspicuous the orange pelage would be to these predators. Am. J. Primatol. 59:67–91, 2003. © 2003 Wiley‐Liss, Inc.
Prevalence of antibodies to selected viruses in a long‐term closed breeding colony of rhesus macaques (Macaca mulatta) in Brazil
Authors: Andrade Marcia Ribeiro , Yee Joann , Barry Peter , Spinner Abigail , Roberts Jeffrey A. , Cabello Pedro H. , Leite Jose Paulo , Lerche Nicholas W.
Published: March 2003

The rhesus macaque breeding colony of the Oswaldo Cruz Foundation (FIOCRUZ) was established in 1932 from a founding stock of 100 animals. This population has remained closed to new animal introductions for almost 70 years. A serologic survey was performed to determine the prevalence of antibodies to selected viruses as a first approach to identifying viral pathogens endemic in this population. Banked serum samples were tested for antibodies to simian immunodeficiency virus (SIV), simian T‐lymphotropic virus (STLV), simian type D retrovirus (SRV), cercopithecine herpesvirus type‐1 (B virus), rhesus cytomegalovirus (RhCMV), measles virus (MV), and hepatitis A virus (HAV). All samples were negative for antibodies against the simian retroviruses. The overall prevalence of antibodies was 95% for RhCMV, 45% for B virus, 35% for HAV, and 1% for MV. Prevalence was found to vary by age group. Am. J. Primatol. 59:123–128, 2003. © 2003 Wiley‐Liss, Inc.
meso‐Verbindungen, Stiefkinder oder Lieblingskinder der stereoselektiven Synthese?
Authors: Hoffmann Reinhard W.
Published: March 2003

Das Methoden‐Arsenal der stereoselektiven Synthese scheint nach mehr als einem Vierteljahrhundert intensiver Entwicklung voll ausgereift zu sein. Im Einklang damit wird auch das Potenzial, das meso‐Verbindungen in der stereoselektiven Synthese zukommt, klar erkannt. Es ist deswegen überraschend, dass die Anwendung von meso‐Verbindungen in der stereoselektiven Synthese in keiner Weise diesem Potenzial entspricht, denn ironischerweise ist die Synthese von meso‐Verbindungen selbst ein Problem der stereoselektiven Synthese – ein Problem, für dessen Lösung die heutigen Methoden nur bedingt hilfreich sind. In diesem Aufsatz werden die Strategien vorgestellt, die sich für die Synthese komplizierterer meso‐Verbindungen eignen, deren stereogene Zentren einen Abstand >1,4 haben. Hierbei werden auch meso‐Verbindungen mit mehr als vier stereogenen Zentren berücksichtigt. Die Kriterien zur Bewertung der verschiedenen Strategien und deren Kombinationen in der Synthese werden herausgestellt.
Direct Synthesis of Propylene Oxide with CO2 as the Solvent
Authors: Danciu Tiberiu , Beckman Eric J. , Hancu Dan , Cochran Robert N. , Grey Roger , Hajnik Dennis M. , Jewson Jennifer
Published: March 2003

Das Oxidationsmittel H2O2 entsteht in situ bei dieser sauberen einstufigen Umsetzung von Propylen in Propylenoxid. Entgegen den Erwartungen benötigt der Katalysator – Palladium auf Titan‐Silicalit – kein Methanol zur Aktivierung, und Nebenreaktionen mit dem Lösungsmittel lassen sich vermeiden, indem die Reaktion in CO2 ausgeführt wird.
Organic Templates for the Generation of Inorganic Materials
Authors: van Bommel Kjeld J. C. , Friggeri Arianna , Shinkai Seiji
Published: March 2003

Mankind's fascination with shapes and patterns, many examples of which come from nature, has greatly influenced areas such as art and architecture. Science too has long since been interested in the origin of shapes and structures found in nature. Whereas organic chemistry in general, and supramolecular chemistry especially, has been very successful in creating large superstructures of often stunning morphology, inorganic chemistry has lagged behind. Over the last decade, however, researchers in various fields of chemistry have been studying novel methods through which the shape of inorganic materials can be controlled at the micro‐ or even nanoscopic level. A method that has proven very successful is the formation of inorganic structures under the influence of (bio)organic templates, which has resulted in the generation of a large variety of structured inorganic structures that are currently unattainable through any other method.
Fracture morphology of Mg(OH)2/polypropylene composites modified by functionalized polypropylene
Authors: Qiu Yixin , Lin Zhidan , Mai Kanchen
Published: March 2003

The morphologies of the fracture surface under impact and flexural testing of Mg(OH)2/Polypropylene (PP) composites and their modified composites were investigated by scanning electron microscopy. Experimental results indicated that addition of functionalized polypropylene (FPP) and acrylic acid (AA) and the formation of in situ FPP changed the fracture morphologies of Mg(OH)2/PP composites. We believe that addition of these modifiers improved the interfacial interaction and enhanced the interface adhesion between the particle and the matrix in Mg(OH)2/PP composites. The degree of improvement was more significant in Mg(OH)2/PP composites modified by the formation of in situ FPP. At low Mg(OH)2 content, 2 phr AA exhibited a marked effect, but at high Mg(OH)2 content, 4 phr AA afforded good effect. Due to the improved interface adhesion by interface interactions the fracture mechanism transformed from interface debonded fracture into a matrix fracture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2148–2159, 2003
Atom transfer radical bulk polymerization of methyl methacrylate under microwave irradiation
Authors: Zhu Xiulin , Zhou Nianchen , He Xiaomei , Cheng Zhenping , Lu Jianmei
Published: March 2003

Microwave irradiation (MI) was applied to the atom transfer radical bulk polymerization of methyl methacrylate. The influence of the amount of the refluxing solvent used for controlling the polymerization temperature, irradiation power, irradiation time, and initiator concentration on the conversion, molecular weight, and molecular weight distribution of the polymers was studied with a benzyl chloride/cuprous chloride/2,2′‐bipyridyl initiation system and compared with the corresponding conventional heating (CH) process. In comparison with CH, the results can be summarized as follows. The polymerization rate for reaching 70% conversion increased 2.6–5.1 times under an irradiation power of 270–630 W. The apparent increasing rate constant was much larger than that with CH and increased with the irradiation power. MI produced a higher polymerization rate and conversion even if the concentration of the initiation system was very low (initial monomer concentration/initial initiator concentration = 200:0.33 mol/mol) and the polydispersity index (DI) was narrower; however, CH yielded almost no polymers. MI promoted the activities of the catalyst and monomer, and its initiation efficiency was higher than that with CH and increased with the irradiation power. MI obviously played an important role in promoting the polymerization rate of atom transfer radical polymerization (ATRP). MI reduced the concentration of the initiation system and perhaps made ATRP controlled (cf. uncontrolled ATRP with CH); at the same time, it made the DI values of the polymers narrower. In comparison with the initiation efficiencies found with benzyl bromide and 2,2′‐azobisisobutyronitrile used as initiators, the initiation efficiency with p‐toluene sulfonyl chloride used as an initiator was higher; moreover, DI was much narrower (1.17), and the polymerization rate was greater. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1787–1793, 2003
Study on the polymerization of ϵ‐caprolactam in the interlamellar spaces of [TEACOOH]–montmorillonite intercalations complex and its characterization
Authors: Cho Sung‐Jun
Published: March 2003

The polymerization of ϵ‐caprolactam between the interlamellar spaces of the [TEACOOH]–montmorillonite intercalations complex was attempted using Na–montmorillonite and 10‐carboxy‐n‐decyltriethylammonium bromide to achieve [TEACOOH]–polycaprolactam–montmorillonite, in which montmorillonite (inorganic polymer) is chemically bonded with the polycaprolactam (organic polymer). The results of X‐ray and IR analysis for the samples obtained after polymerization showed that the polymerization reaction has been successfully accomplished. For the purpose of studying the polymeric reaction product more precisely, we have isolated the polymerized product from the silicate layers and analyzed it with X‐ray diffractometer and IR spectrometer. Comparison of the results of X‐ray and IR analysis between the isolated polymer and the polymer that was synthesized by the reaction of ϵ‐caprolactam only with the organic cation without montmorillonite showed that both obtained polymers are the same compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1904–1910, 2003
Selective plasma‐induced grafting of polystyrene onto polyolefin blends
Authors: Keen I. , George G. A. , Fredericks P. M.
Published: March 2003

Plasma pretreatment has been used to generate reactive radicals and oxygenated groups on polymer surfaces for graft polymerization. The polymer substrates studied were composed of a polypropylene–polyethylene (PP–PE) copolymer, which was predominantly PP, and also contained blended ethylene–propylene rubber (EPR) as either about 15 or about 60 mol %. A pure PP substrate was also studied for comparison. The grafted polymer was polystyrene (PS). Raman microspectroscopic 2‐dimensional mapping was used to elucidate the role of crystallinity and EPR in the plasma treatment and graft polymerization process. It was found that the plasma pretreatment favored the EPR component of the substrate and the graft yield was related to the EPR content. Crystallinity seemed to have a much less significant effect on the grafting reaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1643–1652, 2003
Synthesis, characterization, and reactivity ratios of copolymers derived from 4‐nitrophenyl acrylate and n‐butyl methacrylate
Authors: Thamizharasi S. , Gnanasundaram P. , Balasubramanian S.
Published: March 2003

Free‐radical copolymerization of 4‐nitrophenyl acrylate (NPA) with n‐butyl methacrylate (BMA) was carried out using benzoyl peroxide as an initiator. Seven different mole ratios of NPA and BMA were chosen for this study. The copolymers were characterized by IR, 1H‐NMR, and 13C‐NMR spectral studies. The molecular weights of the copolymers were determined by gel permeation chromatography and the weight‐average (Mw) and the number‐average (Mn) molecular weights of these systems lie in the range of 4.3–5.3 × 104 and 2.6–3.0 × 104, respectively. The reactivity ratios of the monomers in the copolymer were evaluated by Fineman–Ross, Kelen–Tudos, and extended Kelen–Tudos methods. The product of r1, r2 lies in the range of 0.734–0.800, which suggests a random arrangement of monomers in the copolymer chain. Thermal decomposition of the polymers occurred in two stages in the temperature range of 165–505°C and the glass transition temperature (Tg) of one of the systems was 97.2°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1817–1824, 2003
Following network formation in an epoxy/amine system by ultrasound, dielectric, and nuclear magnetic resonance measurements: A comparative study
Authors: Challis R. E. , Unwin M. E. , Chadwick D. L. , Freemantle R. J. , Partridge I. K. , Dare D. J. , Karkanas P. I.
Published: March 2003

This article presents a comparison of data obtained from a low‐temperature cure of an epoxy/amine system by three independent cure monitoring techniques: ultrasonic wave propagation, dielectric permittivity, and nuclear magnetic resonance. The sizes and thermal histories of the samples studied by the three techniques were controlled for comparability between the methods. The three techniques gave consistent information on the progress of cure and were complementary, in that each was particularly sensitive to different stages of the cure process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1665–1675, 2003
Synthesis and dynamic mechanical behavior of crosslinked copolymers and IPNs from vegetable oils
Authors: Yin Yeping , Yao Shuren , Zhou Xueyong
Published: March 2003

Crosslinked copolymers and IPNs were synthesized from vegetable oils (e.g., cottonseed oil, castor oil, and tung oil). The dynamic mechanical behavior of the polymer blends was studied by Dynamic Mechanical Spectroscopy (DMS). The tan δ–temperature curves of these kinds of copolymers and IPNs show a single peak, which indicate good compatibility. They represent a kind of damping materials with high tan δ values over wide temperature ranges. Thus a new way has been found to use natural products of agriculture to produce damping materials. Effects of various factors on the dynamic mechanical behavior were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1840–1842, 2003
Poly(2‐hydroxyethylmethacrylate)/chitosan dye and different metal‐ion‐immobilized interpenetrating network membranes: Preparation and application in metal affinity chromatography
Authors: Bayramoğlu Gülay
Published: March 2003

Composite membranes were synthesized with 2‐hydroxyethylmethacrylate and chitosan (pHEMA/chitosan) via an ultraviolet‐initiated photopolymerization technique in the presence of an initiator (α,α′‐azobisisobutyronitrile). The interpenetrating network (IPN) membranes were improved by the immobilization of dye molecules via hydroxyl and amino groups on the membrane surfaces from the IPNs. A triazidine dye (Procion Green H‐4G) was covalently immobilized as a ligand onto the IPN membranes. The protein showed various affinities to different chelated metal ions on the membrane surfaces that best matched its own distribution of functional sites, resulting in a distribution of binding energies. In support of this interpretation, two different metal ions, Zn(II) and Fe(III), were chelated with the immobilized dye molecules. The adsorption and binding characteristics of the different metal‐ion‐chelated dye‐immobilized IPN membranes for the lysozyme were investigated with aqueous solutions in magnetically stirred cells. The experimental data were analyzed with two adsorption kinetic models, pseudo‐first‐order and pseudo‐second‐order, to determine the best fit equation for the adsorption of lysozyme onto IPN membranes. The second‐order equation for the lysozyme–dye–metal‐chelated IPN membrane systems was the most appropriate equation for predicting the adsorption capacity for all the tested adsorbents. The reversible lysozyme adsorption on the dye‐immobilized and metal‐ion‐chelated membranes obeyed the Temkin isotherm. The lysozyme adsorption capacity of the pHEMA/chitosan dye, pHEMA/chitosan dye–Zn(II), and pHEMA/chitosan dye–Fe(III) membranes were 2.54, 2.85, and 3.64 mg cm−2, respectively. The nonspecific adsorption of the lysozyme on the plain pHEMA/chitosan membrane was about 0.18 mg cm−2. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1843–1853, 2003
Strategies for maximizing free‐radical grafting reaction yields
Authors: Hu Guo‐Hua , Li Huxi , Feng Lian‐Fang , Pessan Luiz Antonio
Published: March 2003

It is very challenging to obtain very large amounts of vinyl monomers grafted onto polymer backbones in the melt through a free‐radical mechanism. The objective of this study was to develop strategies that would allow one to maximize the amount of 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) grafted onto polypropylene (PP) by reactive extrusion processes. For that purpose, an internal batch mixer was used to simulate potential reactive extrusion processes. Two strategies were studied: The first one was to apply the comonomer concept developed in previous studies. More specifically, styrene (St) was used as a comonomer to control the grafting yield and the molar mass of TMI‐grafted PP. The second strategy delt with the feeding mode of the reactants. Two feeding modes were investigated: (a) one‐pot feeding, that is, the total amount of TMI, St, and a peroxide were premixed with PP and the whole mixture was then charged to the reactor at once; (b) stepwise feeding, that is, the total amount of TMI, St, and the peroxide was divided in several equal fractions. The first fraction of the mixture was premixed with PP and then charged to the reactor. After a certain reaction time, the other fractions were charged to the reactor one after another in certain time intervals. Both strategies were shown to be very good at maximizing free‐radical grafting reaction yields. They can be easily adopted if free‐radical grafting is to be carried out by reactive extrusion in a screw extruder. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1799–1807, 2003
Electron beam curing of aliphatic unsaturated polyesters. I. Mechanistic study on converting to pressure‐sensitive adhesives
Authors: Ebe Kazuyoshi , Sasaki Takashi
Published: March 2003

Aliphatic unsaturated polyesters (UPEs) mixed with N, N‐diethylaminoethyl methacrylate (DEAEMA) were convertible by electron beam irradiation to soft solids of high peeling strength. Double bond conversions, gel contents, molecular weight distributions, and crosslinking densities of the irradiated mixtures were studied in comparison with those of UPE–vinyl acetate mixtures, which gave very low peel strength on irradiation. The latter system started gel formation even at earlier stages of irradiation and had higher cross‐linking densities as a result of copolymerization between polyester and monomer double bonds. In contrast, the UPE–DEAEMA system exhibited slow gel formation with predominant conversion of monomer double bonds, indicating formation of graft copolymers. This system also had lower crosslinking densities than the other system. Therefore, it was concluded that the pressure‐sensitive adhesive nature of the electron‐beam‐cured UPE–DEAEMA mixtures could be attributed to the formation of flexible graft polymers entangled in a loosely crosslinked network. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1854–1857, 2003
Viscoelastic behavior of chlorinated polyethylene/poly(ethylene‐co‐vinyl acetate) blends in the melt state
Authors: Shumsky V. F. , Getmanchuk I. P. , Davydenko V. V. , Lipatov Y. S. , Cassagnau Ph. , Boiteux G. , Melis F.
Published: March 2003

Blends of chlorinated polyethylene and an ethylene vinyl acetate copolymer of various compositions were prepared by mixing in the melt state. Dynamic rheological properties of these blends were studied at different temperatures below, near, and above the TS, the temperature of phase separation, and in a frequency range from 0.01 to 100 rad/s. It is shown that the time–temperature superposition principle is suitable in all investigated temperature ranges. G′ versus G″ representations for the blends were found to be independent of temperature and varying weakly with the composition. Changes in the relaxation spectra H(τ) were discovered which depend on the prehistory of the blend preparation and on thermal conditions in the working unit of a rheometer (increasing the temperature from 140 to 180°C or decreasing the temperature from 180 to 140°C). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1911–1918, 2003
Study on the properties of polyethylene–octene elastomer/wood flour blends
Authors: Liao Hsin‐Tzu , Wu Chin‐San
Published: March 2003

In the present study, the properties of metallocene polyethylene–octene elastomer (POE) and wood flour (WF) blends were examined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), an Instron mechanical tester, and scanning electron microscopy (SEM). The results showed that the mechanical properties of POE were obviously lowered, due to the poor compatibility between the two phases, when it was blended with WFs. A fine dispersion and homogeneity of WF in the polymer matrix could be obtained when acrylic acid‐grafted POE (POE‐g‐AA) was used to replace POE for manufacture of the blends. This better dispersion is due to the formation of branched and crosslinked macromolecules since the POE‐g‐AA copolymer had carboxyl groups to react with the hydroxyls. This is reflected in the mechanical and thermal properties of the blends. In comparison with a pure POE/WF blend, the increase in tensile strength at break was remarkable for the POE‐g‐AA/WF blend. The POE‐g‐AA/WF blends are more easily processed than are the POE/WF blends, since the former had a lower melt viscosity than that of the latter. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1919–1924, 2003
Epoxy–imide resins from 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]propane: Adhesive and thermal properties
Authors: Abraham Ginu , Packirisamy S. , Vijayan T. M. , Ramaswamy R.
Published: March 2003

Epoxy–imide resins were obtained by curing the epoxy resin Araldite® GY 250 (DGEBA; difunctional) and Araldite® EPN 1138 (Novolac epoxy; polyfunctional) with the diimide–diacid, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]propane. The adhesive lap shear strength of epoxy–imide resins at room temperature and at 100 and 150°C was determined on a stainless‐steel substrate. The effect of solvent on the adhesive strength of epoxy–imide resins was studied, and tetrahydrofuran was found to give the best results for improving the wetting behavior of epoxy resins. It is observed that with the increase in imide content the adhesive strength at room temperature as well as at elevated temperature increases when tetrahydrofuran is used as a solvent in the adhesive formulation. The room temperature adhesive strength for GY 250‐based systems is in the range of 20.8–23.5 MPa and 45–58% of this strength is retained at 150°C. For EPN 1138‐based systems, the room temperature adhesive strength is in the range of 14.3–20.3 MPa, and in fact, an increase in adhesive strength by 1–26% is observed at 150°C. All these systems are stable up to 370°C, and char residues of GY 250‐ and EPN 1138‐based systems at 800°C are in the range of 27–31 and 33–41%, respectively, in nitrogen atmosphere. The overall thermal stability and retention of room temperature adhesive strength at elevated temperature are higher for EPN 1138‐based systems when compared to those of GY 250‐based systems, and this observation has been attributed to the higher crosslinking possible for EPN‐based systems when compared to GY 250‐based systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1737–1746, 2003
Study of conformational changes in poly(3‐dodecylthiophene) dependent on backbone stereoregularity using a spin‐probe technique
Authors: Šeršeň F. , Čík G. , Veis P.
Published: March 2003

Poly(3‐dodecylthiophene) (P3DDT), with different amounts of head‐to‐head configuration defects, was characterized by ultraviolet–visible, 1H‐NMR, photoluminescence, and Raman spectra. The heat‐induced conformational sample changes were studied by electron paramagnetic resonance (EPR). For the study of these changes, a spin‐probe technique was used, in which 5‐doxyl‐stearic acid methyl ester was applied as a spin probe. From the EPR spin‐probe spectra, rotational correlation times and order parameters were calculated. The heat‐induced conformational changes of P3DDT were accompanied by a monotonic decrease in the rotational correlation time up to approximately −33°C (240 K) and then by an increase in the range of the glass‐transition temperatures, with the maximum being near room temperature and depending on the effective conjugation length. Afterward, the rotational correlation times had a decreasing tendency up to 90°C (363 K). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2215–2223, 2003
Surface and printing properties of synthetic film papers
Authors: Danella Oswaldo J. , Santana Ruth Campomanes , Manrich Sílvio , Manrich Sati
Published: March 2003

We studied the surfaces, including both the composition effects and the processing rates, of polypropylene (PP) composite films used for synthetic paper to determine the surface free energy (γs) and the irregularities on the film surfaces. We correlated these two characteristics to the printing quality by assessing the facility with which the offset ink was removed from the surface of the paper and also the ink absorption. Five films with different compositions were uniaxially oriented with a flat‐die extruder at two different stretching rates. The results of scanning electron microscopy (SEM) of the films showed good dispersion and distribution of the filler particles used in the compositions of the films and also of the polystyrene (PS) dispersed throughout the PP matrix. The SEM analysis also revealed slightly high surface irregularities on the film surfaces through a high concentration of CaCO3, which thus increased the coefficients of static and kinetic friction and the γs values. These film properties created better printing quality and also more strongly fixed offset ink onto the film. However, the films with high relative quantities of PS in their composition showed a high polar component in their total γs when compared to films with less PS or no PS in their compositions. However, because of the apolar characteristic of the offset printing ink, the ink absorption worsened. The films underwent stretching at two different rates, which did not significantly affect the γs values or the friction coefficients; however, they did slightly change the printing quality and ink adhesion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2346–2355, 2003
Effects of swelling agents on the crystallization behavior and mechanical properties of polyamide 6/clay nanocomposites
Authors: Ma Chen‐Chi M. , Kuo Chun‐Ting , Kuan Hsu‐Chiang , Chiang Chin‐Lung
Published: March 2003

Montomorillonite was organically modified with three different swelling agents: n‐dodecylamine, 12‐aminolauric acid, and 1,12‐diaminodecane. These organoclays and polyamide 6 (PA6) were blended in a formic acid solution. X‐ray diffraction analysis showed that the clay still retained its layer structure in the PA6/clay nanocomposite. Consequently, these materials were intercalated nanocomposites. The effects of the swelling agent and organoclay content on the crystallization behavior of the PA6/clay nanocomposites were studied with differential scanning calorimetry. The results showed that the position and width of the exothermic peak of the PA6/clay nanocomposites were changed during the nonisothermal crystallization process. The clay behaved as a nucleating agent and enhanced the crystallization rate of PA6.The crystallinity of PA6 decreased with an increasing clay content. Different swelling agents also affected the crystallization behavior of PA6. The effects of the type and content of the swelling agent on the tensile and flexural properties of PA6/clay nanocomposites were also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1686–1693, 2003