bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating class I differentials in the new federal milk marketing order system
Authors: Kawaguchi Tsunemasa , Suzuki Nobuhiro , Kaiser Harry M.
Published: August 2002

In this article, a spatial equilibrium model that allows for the inclusion of any degree of market structure from perfect competition to monopoly is developed and applied to the U.S. dairy industry. This model is used to simulate possible Class I premiums, which could be negotiated by U.S. dairy cooperatives in the absence of FMMOs, under alternative assumed market structures. These premiums are then compared with the newly adopted Class I differentials to determine what degree of market competitiveness is equivalent to the new Class I differential structure. The results suggest the new FMMO Class I differentials are equivalent to a small degree of imperfect competition. In addition, because Class I differentials virtually disappear in the perfect competition case, our findings indicate it is difficult to justify the existence of Class I differentials solely on the basis of transportation costs from surplus to deficit areas [EconLit citations: Q11, Q13, Q18]. © 2001 John Wiley & Sons, Inc.
Economics of the use of imported U.S. high oil corn in swine and poultry rations in Taiwan
Authors: Yu Tun‐Hsiang , Baumel C. Phillip , McVey Marty J. , Sell Jerry L.
Published: August 2002

High oil corn (HOC) is a genetically enhanced variety of corn that is gaining popularity as a commercial feed ingredient. HOC has an enlarged germ and contains higher levels of crude oil, protein, and amino acids than conventional corn. To capture the increased feed benefits of HOC, it must remain identity preserved. In addition to identity preservation costs, HOC typically has lower yields and higher seed costs. The purpose of this study is to examine the added value of two types of HOC in commercial poultry and swine rations in Taiwan. A linear programming model is used to estimate the value of the two HOC in least cost feed rations. Additional handling, transport, yield drag, and seed costs are subtracted from the estimated added values of HOC in the rations to estimate the profitability of importing HOC corn into Taiwan. The results suggest some alternatives for increasing U.S. exports of HOC. [Econ‐Lit citations: Q17]. © 2001 John Wiley & Sons, Inc.
A Markov chain analysis of the size of hog production firms in the United States
Authors: Gillespie Jeffrey M. , Fulton Joan R.
Published: August 2002

The U.S. hog industry expanded rapidly during the 1980s and 1990s. Along with this expansion, hog farms have become larger, partly due to economies of size and new business arrangements. Using markov chain analysis, this study analyzes the movement of hog farms among three different size categories. Results indicate that the hog–corn price ratio has continued to affect the entry and exit of small hog farms, and has influenced the movement of hog farms among size categories. Interest rates, processing capacity, and agglomeration economies have impacted new entry of hog farms in the Unites States [L110, L230]. © 2001 John Wiley & Sons, Inc.
Origin of Fueguian‐Patagonians: An approach to population history and structure using R matrix and matrix permutation methods
Authors: José Rolando González , García‐Moro Clara , Dahinten Silvia , Hernández Miquel
Published: August 2002

A complicated history of isolation between Fueguian and Patagonian groups (originated by the appearance of the Straits of Magellan) as much as differences in population structure and life strategies constitute important factors in the clustering pattern of those groups. The aim of this work was to test several hypotheses about population structure and history of Fueguian‐Patagonians to propose a model that incorporates predictions for future studies. R matrix methods and matrix permutation analyses were performed upon a data matrix of craniofacial measurements of 441 skulls divided into nine samples pertaining to six Patagonian and three Fueguian populations. Association of biological distances with three matrices representing several settlement patterns was tested using matrix permutation tests. Results of R matrix study show that the minimum genetic distance obtained confirms separation between Fueguians and Patagonians. Moreover, an analysis of residual variances from the expected regression line confirms admixture between Andean and Pampean populations and Araucanian groups, consistent with ethnohistorical observations. A model representing a long history of isolation between Fueguian and Patagonians, rather than a model emphasizing differences in life‐strategies, presented the best correlation with the biological distance matrix. Because similar results were already obtained in archaeological, molecular, and morphological studies, a model for the settlement of Tierra del Fuego is proposed. It is summarized by four main hypotheses that can be tested independently by different disciplines in the future. Am. J. Hum. Biol. 14:308–320, 2002. © 2002 Wiley‐Liss, Inc.
Transient hand paresthesias in Champagne vineyard workers
Authors: Roquelaure Yves , Gabignon Y. , Gillant J.C. , Delalieux P. , Ferrari C. , Méa M. , Fanello S. , Penneau‐Fontbonne D.
Published: August 2002

Background

The aim of the study was to assess the prevalence of hand paresthesias (HP) and their relationship with pruning activities.

Methods

A cross‐sectional study was conducted among 537 workers pruning grapevines in the region of Champagne. All workers completed a questionnaire about nocturnal HP and musculoskeletal pain during the preceding 12‐month period.

Results

The 12‐month prevalence of nocturnal HP and hand‐wrist pain were 37 and 12%, respectively. HP, predominantly affecting the dominant hand, only began during the pruning period and ended after the pruning season in 90% of cases. HP were transient in most cases, with a mean duration of symptoms of 3.3 ± 3.2 months. Risk factors associated with HP were: female gender (OR = 2.3 [1.3–3.0]), being overweight (OR = 1.6 [1.1–2.5]), payment on a piecework basis (OR = 2.0 [1.2–2.3]) and traditional blade sharpening method (OR = 1.7 [1.1–2.7]). HP were less frequent in employees who used electric pruning shears (OR = 0.5 [0.2‐1.6], P = 0.09).

Conclusions

The development of HP, which affected a third of employees, was different from HP observed in industrial workers since most vineyard workers recovered without medical treatment after the pruning season. Am. J. Ind. Med. 40:639–645, 2001. © 2001 Wiley‐Liss, Inc
Re: Benzene and lymphohematopoietic malignancies in humans. Hayes et al. Am. J. Ind. Med. 40:117–126, 2001
Authors: Robbins Anthony
Published: August 2002

The excellent review of exposure to benzene and resulting leukemia and other hematopoietic disorders by Hayes et al. [2001] enhances our knowledge about one of the most widely used carcinogenic chemicals. The review reinforces the observation that benzene causes hematopoietic malignancies at lower levels than earlier described. It confirms for us that the biological mechanism or mechanisms by which benzene causes these malignant transformations are not fully understood. It places the recent results of a US National Cancer Institute/Chinese Academy of Preventive Medicine Research Project in the context of older studies about benzene.

For all the merit of this research review, it prompts me to raise several critical questions for all researchers dedicated to protecting workers. I arrive at these questions not solely from our experience studying benzene, but from the broad and encouraging history of occupational health research, as well as our rather discouraging record for applying the scientific results.
Evidence for an N‐glycosylation polymorphism of arylsulfatase a predisposing to alcoholism in Koreans
Authors: Chung In‐Won , Kim Heon , Lee Sang‐Ick , Hong Joo‐Bong , Kim Yong‐Dae , Nan Hong‐Mei , Sribney William , Kim Yong‐Sik , Manowitz Paul
Published: August 2002

This study investigated the possible effect of the pseudodeficient N‐glycosylation polymorphism of the arylsulfatase A (ASA) gene on alcohol dependence among Koreans. Alcoholic patients (N = 123) were more likely than control subjects to be heterozygous or homozygous for the ASA pseudodeficient N‐glycosylation site (36% of alcoholics versus 20% of controls; P < 0.01). Among these 123 alcoholic patients, 42 alcoholics were heterozygous and two were homozygous for the ASA pseudodeficient N‐glycosylation polymorphism. This result provides evidence that the ASA pseudodeficient N‐glycosylation site allele increases the risk of alcohol dependence within a Korean population. © 2002 Wiley‐Liss, Inc.
Association analysis of polymorphisms at the interleukin‐1 locus in essential hypertension
Authors: Lin Ruby C.Y. , Morris Brian J.
Published: August 2002

Infection with microorganisms such as Helicobacter pylori and Chlamidia pneumoniae has been associated with coronary heart disease (CAD) and hypertension (HT). Infection increases the release of pro‐inflammatory cytokines, thus facilitating interactions that lead to vascular damage and other effects. We hypothesized that genetically determined differences in activity or responsiveness of cytokine(s) might contribute to HT. The interleukin‐1 gene (IL1) cluster on chromosome 2q14 contains three related genes (IL1A, IL1B, and IL1RN) located within a 430‐kb region. These encode IL‐1α and IL‐1β, as well as their endogenous receptor antagonist, IL‐1ra. The IL1RN gene has a penta‐allelic 86‐bp tandem repeat in intron 2. Allele IL1RN* 2 is associated with a wide range of chronic inflammatory and autoimmune conditions, and its combination with the − 31T variant of an IL1B C(− 31)T polymorphism constitutes a pro‐inflammatory haplotype that leads to vigorous IL‐1β production. We therefore tested each of these polymorphisms for association with HT. Subjects were white Anglo‐Celtic residents of Sydney, Australia. Frequencies of IL1B C(− 31)T genotypes CC, CT, and TT were 0.50, 0.40, and 0.10 in normotensive (NT) and 0.46, 0.46, and 0.08 in HT, respectively (χ2 = 1.2, P = 0.55). T allele frequency in NT (0.30) was similar to that in HT (0.31). For the IL1RN variant, frequencies of alleles IL1RN* 1 and * 2 and combined minor alleles * 3, * 4, and * 5 were 0.61, 0.36, and 0.03 in NT and 0.54, 0.36, and 0.10 in HT, respectively (χ2 = 11, P = 0.004). In conclusion, no association of the IL1B C(− 31)T with HT was found, whereas combined frequency of the minor alleles of the IL1RN polymorphism was increased in the HT cohort studied. © 2001 Wiley‐Liss, Inc.
No evidence of an association between a functional monoamine oxidase a gene polymorphism and completed suicides
Authors: Ono Hisae , Shirakawa Osamu , Nishiguchi Naoki , Nishimura Akiyoshi , Nushida Hideyuki , Ueno Yasuhiro , Maeda Kiyoshi
Published: August 2002

Monoamine oxidase A (MAOA) has been implicated in the control of aggression and/or impulsivity in humans and been involved in suicide. This gene has a functional polymorphism in which there is a variable number tandem repeat (VNTR) in the upstream region (MAOA‐uVNTR). We hypothesized that MAOA dysfunction due to this polymorphism was associated with suicide genetically through the disinhibition of aggression and/or impulsivity. We performed an association study between completed suicides and the MAOA‐uVNTR polymorphism. No significant difference in genotype distribution or allele frequencies was found between completed suicides and comparison groups either in males or females. These results show no evidence of an association between the MAOA‐uVNTR polymorphism and completed suicides and suggest that MAOA is not involved in the susceptibility to suicide. © 2002 Wiley‐Liss, Inc.
Molecular evidence of presenilin 1 mutation in familial early onset dementia
Authors: Matsubara‐Tsutsui Miho , Yasuda Minoru , Yamagata Hidehisa , Nomura Takuo , Taguchi Keiko , Kohara Katsuhiko , Miyoshi Koho , Miki Tetsuro
Published: August 2002

Early onset familial Alzheimer disease (FAD) has been associated with mutations in three genes, of which presenilin 1 (PSEN1) mutations are the most frequent. We reported previously a variant form of FAD, due to deletion of exon 9 of PSEN1, with spastic paralysis and rigidity. We describe a novel PSEN1 mutation in a family of Japanese origin with six affected individuals of both genders in two generations. The disease is characterized by presenile dementia, which is preceded by spastic paraparesis and apraxia. This mutation, which is predicted to cause a missense substitution of serine for glycine, occurred at codon 266 in exon 8 of PSEN1. The mutation was not found in 200 controls and 200 sporadic AD patients. On this basis alone, it seems this mutation is pathogenic. Our findings provide a new clue to the etiology of the familial early onset dementia. © 2002 Wiley‐Liss, Inc.
Report from the second international meeting of the attention deficit hyperactivity disorder Molecular Genetics Network
Authors: Faraone Stephen V.
Published: August 2002

Given evidence from twin, family, and adoption studies of genetic influence on attention deficit hyperactivity disorder (ADHD), a growing number of researchers have initiated molecular genetics studies to explore the influence of specific genes on this condition. In 1999, these investigators convened to discuss ways of sharing information and facilitating collaborations across research sites. Enthusiastic response to this first conference prompted an even larger group of investigators to come together this year. This recent meeting, held in London, began with a presentation of Hypescheme, an operational criteria checklist developed in an effort to promote the reliable communication of diagnostic and other relevant clinical information related to ADHD. The benefits and limitations of Hypescheme, as well as the continued challenges to collaboration, were discussed. A new ADHD‐specific rating scale, developed to be of use in genetic analyses, was also presented. Focus then turned to collaborative projects proposed by investigators and practical suggestions regarding joint data analyses projects. Finally, new data from individual sites were presented. Because the mode of inheritance of ADHD is likely to be complex, efforts to collaborate and cross‐validate findings remain an important priority for researchers studying the molecular genetics of this disorder. © 2001 Wiley‐Liss, Inc.
Allelic variation of a BalI polymorphism in the DRD3 gene does not influence susceptibility to bipolar disorder: Results of analysis and meta‐analysis
Authors: Elvidge Gareth , Jones Ian , McCandless Fiona , Asherson Phil , Owen Michael J. , Craddock Nick
Published: August 2002

Bipolar disorder is a major psychiatric illness that has evidence for a significant genetic contribution toward its development. In recent years, the BalI RFLP (restriction fragment length polymorphism) in the dopamine D3 receptor gene has been examined as a possible susceptibility factor for both schizophrenia and bipolar disorder. While analysis in schizophrenia has produced examples of increased homozygosity in patients, less encouraging results have been found for bipolar disorder. Recently, however, a family‐based association study has found a significant excess of allele 1 and allele 1–containing genotypes in transmitted alleles to bipolar probands over nontransmitted controls. In a large bipolar case control sample (n = 454), we have been unable to replicate the family‐based association study (chi‐square = 0.137, P = 0.71, 1 df) or detect an effect similar to the positive homozygosity findings in schizophrenia (chi‐square = 0.463, P = 0.50, 1 df). A meta‐analysis of previous association studies also revealed no difference in allele distributions between bipolar patients and controls for this polymorphism in ethnically homogeneous samples (odds ratio, OR, = 1.04; P = 0.60; 95% confidence interval, CI, = 0.89–1.20). In view of this evidence, we conclude that variation at the BalI RFLP is not an important factor influencing the susceptibility to bipolar disorder. It remains possible, however, that other sequence variations within the DRD3 gene could play a role. © 2001 Wiley‐Liss, Inc.
Using a roster and haplotyping is useful in risk assessment for persons with intermediate and reduced penetrance alleles in Huntington disease
Authors: Maat‐Kievit Anneke , Helderman‐van den Enden Paula , Losekoot Monique , de Knijff Peter , Belfroid René , Vegter‐van der Vlis Maria , Roos Raymund , Breuning Martijn
Published: August 2002

The risk of a person having a child with an inherited disorder, caused by an unstable triplet repeat, such as Huntington disease (HD), depends on the expansion of the mutation in that person, which is connected both to the biological nature of the mutation and to the person's relation to the carrier of the full mutation. Once the mutation causing HD was identified, we were able to diagnose sporadic patients. A sporadic patient can sometimes be connected to a known HD pedigree by using a roster. By haplotyping and calculating the posterior identity‐by‐descent probability, we could establish whether a connection was coincidental or not. Furthermore, we describe the frequency of intermediate and reduced penetrance alleles detected. Using the family history and the roster to search for a connection, we examined whether these alleles were on the HD haplotype of a family. It is important to know the origin of an intermediate or reduced penetrance allele because if it comes from an HD branch of the family or from the non‐HD affected side of the pedigree, different risks for relatives and penetrance ensue. In our study, most intermediate alleles came from the non–HD‐affected side of the pedigree and had a repeat size in the lower range with a negligible risk for expansion. Intermediate alleles on the HD haplotypes were larger and found in predictive test applicants from known families or relatives from new mutations with a higher risk for expansion. Reduced penetrance alleles in the higher range were mainly found in symptomatic and predictive test applicants from known families, with a considerable risk for penetrance, although at older age. We conclude that a roster, a thorough family history, and haplotyping in persons with intermediate and reduced penetrance alleles are essential in considering the risk of a person having (a child with) HD. © 2001 Wiley‐Liss, Inc.
Morphological differences between minicolumns in human and nonhuman primate cortex
Authors: Buxhoeveden Daniel P. , Switala Andrew E. , Roy Emil , Litaker Mark , Casanova Manuel F.
Published: August 2002

Our study performed a quantitative investigation of minicolumns in the planum temporale (PT) of human, chimpanzee, and rhesus monkey brains. This analysis distinguished minicolumns in the human cortex from those of the other nonhuman primates. Human cell columns are larger, contain more neuropil space, and pack more cells into the core area of the column than those of the other primates tested. Because the minicolumn is a basic anatomical and functional unit of the cortex, this strong evidence showed reorganization in this area of the human brain. The relationship between the minicolumn and cortical volume is also discussed. Am J Phys Anthropol 115:361–371, 2001. © 2001 Wiley‐Liss, Inc.
Degenerative spondylolisthesis in ancient and historic skeletons from New Mexico Pueblo sites
Authors: Merbs Charles F.
Published: August 2002

The objective of this study was to identify the presence of degenerative spondylolisthesis in adult Native American skeletons recovered from prehistoric and historic Pueblo sites in New Mexico. The vertebral columns of 491 individuals that were complete enough to allow the necessary observations produced 64 cases, with a total of 74 affected levels. The L5–S1 level was affected most frequently (78%), in contrast to clinical and anatomical studies where the L4–L5 level was usually affected (80%). Age and sex were found to be important factors, with the condition limited to middle and old adults, and occurring in females over males at a ratio of approximately 5:1. Olisthesis was shown to occur only in association with severe osteoarthritis of the zygapophysial joints, but severe osteoarthritis did not always result in olisthesis, particularly in males. Parallel or convergent inferior articular processes were found to increase in frequency in the presence of olisthesis, apparently resulting from degenerative remodeling that produced the olisthesis. The data also suggest that individuals with cranial border shifting in the column may be especially prone to olisthesis. Degenerative olisthesis was also observed in the cervical region. Am J Phys Anthropol 116:285–295, 2001. © 2001 Wiley‐Liss, Inc.
Ascorbic acid acts as a hydride donor towards ­2‐arsonocarboxylic acids
Authors: Ioannou Panayiotis V. , Siskos Michael G.
Published: August 2002

2‐Arsonohexanoic acid is decomposed during its attempted reduction to 2‐arsenosohexanoic acid by triphenylphosphine in the presence of a catalytic amount of iodine. When ascorbic acid is substituted for the triphenylphosphine, ­hexanoic acid is obtained, implying that the arscorbic acid acts as a hydride donor. Copyright © 2001 John Wiley & Sons, Ltd.
Organotin levels in the Ria Formosa lagoon, Portugal
Authors: Coelho M. R. , Bebianno M. J. , Langston W. J.
Published: August 2002

Organotin concentrations were measured in water, sediments and clams (Ruditapes decussatus) from 11 sites in the Ria Formosa lagoon, Portugal, in 1992–93. Results showed a marked spatial pattern of tributyltin (TBT) and dibutyltin concentrations. The highest organotin concentrations were observed at Olhão (site 5), where the most important fishing harbour of the Southern coast of Portugal is located.

Results indicated that fishing vessels, moored in the harbour at Olhão (site 5), were the major source of organotin contamination to the lagoon. No significant seasonal trend was observed, suggesting a continuous input of organotin compounds throughout the year. In several areas of the lagoon the TBT burdens in R. decussatus could have deleterious developmental effects. Copyright © 2002 John Wiley & Sons, Ltd.
Comparative study of polymer single cells based on sulfonated linear and star butadiene–styrene block copolymer electrolyte membranes
Authors: Mokrini A. , Acosta J. L.
Published: August 2002

Proton‐conducting electrolytes based on a sulfonated hydrogenated poly(butadiene–styrene) matrix were synthesized. Block copolymer ionomers were prepared through sulfonation of part of the styrene units. The free acid samples were characterized with X‐ray photoelectron spectroscopy to quantify sulfonation. Microstructural and electrical characterizations of membranes obtained from sulfonated polymer and blends were carried out with dynamic mechanical analysis, differential scanning calorimetry, and impedance spectroscopy. Electrolytes exhibiting the highest conductivities were tested in a model hydrogen/oxygen single fuel cell working at a medium temperature range (30–80°C) and at 1 bar of pressure. The current and power densities obtained were compared with commercial Nafion electrolyte. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 367–377, 2002
Quantitative determination of the distribution of free hydroxylic and carboxylic groups in unsaturated polyester and alkyd resins by 31P‐NMR spectroscopy
Authors: Spyros A.
Published: August 2002

Quantitative 31P‐NMR spectroscopy is used to measure the hydroxyl and carboxyl content of some polyester resins (short‐ and long‐oil alkyds, polyols, polyesters) through derivatization of the —OH protons with 2‐chloro‐4,4,5,5‐tetramethyldioxaphospholane I. This methodology is shown to be superior to titration methods, since it can (a) discriminate between primary and secondary hydroxyl groups, (b) identify individual alcohols and acids present, (c) measure the amount of free fatty acids in oil‐modified alkyds, and (d) provide lower limits for the number‐averaged molecular weight of the resins and exact values for linear polyesters. A major advantage of the technique is that the NMR measurements are made on unmodified resins in their final product form supplied by the manufacturer. The information obtained is important for the characterization of the alkyd resins and affects drastically their physical properties and performance as products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1635–1642, 2002
Phosphorous‐containing epoxy resins from a novel synthesis route
Authors: Liu Ying Ling
Published: August 2002

The P(O)‐H in 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was used as an active group to react with the carbonyl group in 4,4′‐dihydroxybenzophenone (DHBP) to result a novel phosphorous‐containing biphenol compound (DOPO‐2OH). Phosphorous‐containing epoxy resins were therefore obtained from reacting DOPO‐2OH with epichlorohydrin or with diglycidylether bisphenol A. The synthesized compounds were characterized with FTIR, 1H and 31P NMR, elemental analysis, and epoxide equivalent weight titration to demonstrate the their chemical structures. Cured epoxy resins were prepared via thermal curing the epoxy resins with various curing agents. Thermal analysis results (differential scanning calorimetry and thermogravimetric analysis) revealed that these cured epoxy resins exhibited high glass transition temperatures and high thermal stability. High char yields at 700°C and high LOI (limited oxygen index) values were also found for the cured epoxy resins to imply that the resins were possessing high flame retardancy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1697–1701, 2002
Studies of mechanical and moisture regain properties of methyl methacrylate grafted silk fibers
Authors: Maji Tarun Kumar , Basu Diya , Datta Chandan , Banerjee Amarnath
Published: August 2002

The mechanical properties such as the tenacity, breaking extension, initial modulus, elastic and work recovery, and stress relaxation behavior of methyl methacrylate (MMA) grafted silk fibers prepared under different conditions were measured and explained in terms of the relative dominance of the stress concentration, reduction in the interchain cohesion, and fiber matrix stiffening at different grafting percentages. The moisture regain characteristics of fibers grafted in the presence of different solvents were also studied and compared. The grafting of MMA on silk was found to improve the recovery properties significantly without affecting the stress relaxation behavior. The moisture regain studies indicate that moisture regain is reduced with increasing length of the grafted poly(MMA) chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 969–974, 2002; DOI 10.1002/app.10202
Kinetic investigations of acrylic–polyurethane composite latex
Authors: Kukanja Dolores , Golob Janvit , Krajnc Matjaž
Published: August 2002

The effect of various reaction parameters on the rate of polymerization, Rp, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, Rm, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/Rp = 1/K + 1/Rm. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002
Synthesis and property of nanosized palladium catalysts protected by chitosan/silica
Authors: Huang Aiming , Liu Yinfeng , Chen Lai , Hua Jiadong
Published: August 2002

A chitosan (CTN)/silica‐supported nanosized palladium catalyst was obtained from a silica‐supported chitosan palladium complex through a complex transition method. An adsorption model was employed to simplify the structure of the di‐supporter. It was indicated that when the polymer coil adsorbed on the silica surface with even a monolayer the catalytic activity would reach an optimum value, and different situations of the, nanosized palladium particles would cause a different catalysis. The molar ratio of the chitosan structure unit to the palladium would affect the metal's size, which therefore influenced its catalytic activity. The experimental results corresponded with the inferences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 989–994, 2002
Biodegradability study of copolyesteramides based on diacid chlorides, diamines, and diols
Authors: Pivsa‐Art S. , Nakayama A. , Kawasaki N. , Yamamoto N. , Aiba S.
Published: August 2002

Copolyesteramides were synthesized by polycondensation of diacid chlorides, diamines, and diols of varying methylene group chain length. The composition of the synthesized polymer was determined with nuclear magnetic resonance (NMR) analysis. The biodegradation of the polymers was evaluated both with enzymatic hydrolysis and activated sludge test. The polymers were hydrolyzed with lipases from Rhizopus arrhizus, Rhizopus delemar, Candida cylindracea, and an esterase from hog liver, whereas trypsin and α‐chymotrypsin did not have any apparent effect upon them. Enzymatic hydrolysis was found to be greatly affected by the polymer composition and structure. The degradation results obtained from the activated sludge test were in satisfactory agreement with those from enzymatic hydrolysis. The water‐soluble parts of hydrolyzed products were more susceptible to degradation of their ester bonds rather than their amide bonds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 774–784, 2002
Influence of γ‐irradiation on poly(methyl methacrylate)
Authors: Suarez João Carlos Miguez , Mano Eloisa Biasotto , Da Costa Monteiro Elisabeth Ermel , Tavares Maria Inês Bruno
Published: August 2002

Poly(methyl methacrylate) (PMMA) was γ‐irradiated (5–20 kGy) by a 137Cs source at room temperature in air. The changes in the molecular structure attributed to γ‐irradiation were studied by mechanical testing (flexure and hardness), size‐exclusion chromatography, differential scanning calorimetry, thermal gravimetric analysis, and both Fourier transform infrared and solution 13C‐NMR spectroscopy. Scanning electron microscopy was used to investigate the influence of the dose of γ rays on the fracture behavior of PMMA. The experimental results confirm that the PMMA degradation process involves chain scission. It was also observed that PMMA presents a brittle fracture mechanism and modifications in the color, becoming yellowish. The mechanical property curves show a similar pattern when the γ‐radiation dose increases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 886–895, 2002
Polyanion/gelatin complexes as pH‐sensitive gels for controlled protein release
Authors: Jiang H. L. , Zhu K. J.
Published: August 2002

Polyanion/gelatin complexes including poly(methacrylic acid) (PMAA)/gelatin, poly(acrylic acid) (PAA)/gelatin, and heparin/gelatin are investigated as pH‐sensitive gels for controlled protein release. Polyanions can interact with gelatin and form amorphous precipitates within a certain pH range, which is affected by the polyanion nature. The entrapment efficiency of model proteins (myoglobin, cytochrome c, and pepsin) into the complexes is rather high (>80%). By using a modified colloid titration that mixes a solution of gelatin and model proteins titrated with polyanion solution, myoglobin and cytochrome c are found to interact with polyanions by electrostatic forces at low pH, while pepsin either interacts with the polyanion when the pH is below its isoelectric point (IEP) or complexes with gelatin at a pH above IEPpepsin. At pH 7.4 all the complexes dissociate and proteins are rapidly released within a few hours. The complexes are stable and the proteins are retained within a certain pH range, which is related to the polyanion type (e.g., 5.0–2.0 for PMAA, 4.6–1.2 for PAA, and <4.3 for heparin). The three processes of complex formation, dissociation, and protein release have a good correlation. In addition, the protein release transition takes place within a rather narrow pH range (ca. 0.5 units) and the protein nature has little effect on the protein release profile. The high protein entrapment efficiency and good pH sensitivity of the protein release can be mainly attributed to the electrostatic attractive interactions between proteins and polyanion or gelatin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1416–1425, 2001
Effect of composition and processing conditions on the chemical and morphological evolution of PA‐6/EPM/ EPM‐g‐MA blends in a corotating twin‐screw extruder
Authors: Machado A. V. , Covas J. A. , Walet M. , Van Duin M.
Published: August 2002

This study investigated the effect of blend composition and processing conditions on the chemical conversion and morphological evolution of PA‐6/EPM/EPM‐g‐MA blends along a twin‐screw extruder. The maleic anhydride (MA) content of the modified rubber was found to decrease strongly, to a level of almost zero, and in the melting zone the particle size was dramatically reduced, from millimeters to submicrometers. Blend composition had a secondary effect on both chemical conversion and morphological development. The processing conditions, particularly the temperature profile and the screw speed, affected both the chemical conversion and the morphological evolution. Using low temperatures and low screw rotation it was possible to follow in detail the evolution of morphological development of a reactive blend in a twin‐screw extruder. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1535–1546, 2001
Synthesis and characterization of poly(hydroxyether). II. Poly(hydroxyethers) based on various bisphenols and 2,2‐bis(4‐hydroxypheny)hexafluoropropane
Authors: Tatehata Hideki , Fukuoka Tetsuya , Mochizuki Akira
Published: August 2002

Several kinds of linear copoly(hydroxyethers) (CPHEs) were prepared by the base‐induced condensation of bisphenol with epichlorohydrin in a polar mixed solvent. The CPHEs were based on bisphenol AF [2,2‐bis(4‐hydroxypheny)hexafluoropropane], and the composition ratio of bisphenol AF and bisphenol was 50 : 50 mol/mol. The CPHEs and the corresponding homopoly(hydroxyethers) (HPHEs) were characterized in terms of reduced viscosity, NMR, differential scanning calorimetry (DSC), solubility, and contact angle. NMR results indicated that the compositions of the copolymers were in good agreement with the feed compositions in the preparation. DSC analysis revealed that the CPHEs and HPHEs were amorphous polymers. The incorporation of bisphenol AF into the HPHE increased the solubility in many kinds of organic solvents when the CPHEs were compared with the corresponding HPHE. In the measurement of contact angles of water and plasma for poly(hydroxyethers) (PHEs) and common hydrophobic polymers, the peculiar phenomenon that the contact angles of plasma were higher than that of water was observed only in the case of PHEs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1697–1709, 2001
Synthesis, spectral properties, and application of 1,8‐naphthalimide fluorophores for modified polymers
Authors: Philipova Tz. , Petkov I.
Published: August 2002

The presence of the epoxy group in the structure of 1,8‐naphthalimide fluorophores opens up possibilities to prepare compounds with new valued properties through covalent bonding to both polyamide and epoxy oligomers. Two new 4‐(1‐amino‐2,3‐epoxypropyl)‐9‐substituted‐1,8‐naphthalimides were synthesized, and their absorption and fluorescence characteristics were determined. The introduction of the substituent contributes to both the yellow color and strong fluorescence of the compounds, the quantum yield being about 0.9. The possibility for structural coloration of polyamide textile materials and epoxy oligomers has been investigated. The modified polymers are with intense green fluorescence, possessing a strong resistance to various physico‐chemical treatments and light. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1863–1869, 2001
Nonaqueous emulsion copolymerization of ethyl methacrylate/lauryl methacrylate in propylene glycol. I. Evaluation of stabilizing efficiency for PEO‐PS‐PEO triblock copolymers
Authors: You Xiaorong , Dimonie Victoria L. , Klein Andrew
Published: August 2002

Sixteen poly(ethylene oxide)–polystyrene–poly(ethylene oxide) (PEO‐PS‐PEO) triblock copolymers were synthesized by anionic polymerization. They were characterized by gel permeation chromatography and proton NMR. The molecular weight of these 16 PEO‐PS‐PEO triblock copolymers ranged from 5100 to 13,300. The polystyrene (PS) block length was between 13 and 41. The PEO block length was between 41 and 106. The polydispersity index for these PEO‐PS‐PEO triblock copolymers were 1.05 ± 0.02. When using these stabilizers in the emulsion copolymerization of ethyl methacrylate and lauryl methacylate in propylene glycol, only a narrow window of stability was observed. Stable latexes were formed only when the molecular weights of the PEO blocks were within the range of 5300–7700 and the molecular weights of the PS blocks were 2000–4000. The stabilizer ability for these triblock copolymers was correlated with their molecular weight and conformation in propylene glycol. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1951–1962, 2001
Kinetics of transesterification of dimethyl 2,6‐naphthalenedicarboxylate with 1,3‐propanediol
Authors: Stier U. , Gähr F. , Oppermann W.
Published: August 2002

The kinetics of transesterification of dimethyl 2,6‐naphthalenedicarboxylate (2,6‐DMN) with 1,3‐propanediol has been studied in the presence of various catalysts. The reaction was followed by measurement of the amount of methanol released, and the formation of oligomers with time. The oligomers obtained were quantitatively determined by high‐pressure liquid chromatography (HPLC). Interpretation of the experimental data showed that the transesterification followed Schulz‐Flory statistics. Therefore, one kinetic constant was sufficient to describe the kinetics of transesterification of 2,6‐DMN with 1,3‐propanediol. The kinetic constants observed, when different catalysts were employed, revealed the following activity sequence for the transesterification: Co(II) < Ti(IV) < Mn(II) < Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2039–2046, 2001
Study on electrical conductivity of 2‐vinylpyridine‐methyl methacrylate copolymer in presence of cobalt acetate
Authors: Abed M. Yahia , Hindia Touson A. , Mohamed Manal G. , Mazrouaa Azza M.
Published: August 2002

2‐Vinyl pyridine (2VP)‐methyl methacrylate (MMA) copolymers with different molar ratios were prepared. Their electrical properties were studied in the presence of Co(CH3COO)2. It was found that the electrical properties of the copolymer were changed by altering the molar ratio of 2VP : MMA and by varying the concentration of Co(CH3COO)2. The highest electrical conductivity was found when the 2VP : MMA molar ratio was 1 : 1. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2145–2153, 2001
Influence of some additives on state‐of‐mix, rheological, tensile, and dynamic mechanical properties in SBR compounds
Authors: Sirisinha Chakrit , Sittichokchuchai Weerapen
Published: August 2002

The influence of some additives (Flexon processing oil, Struktol WB 16 slipping agent, and Struktol NS 60 homogenizing resin) on state‐of‐mix, rheological, tensile, and dynamic mechanical properties were investigated. It was found that extrudate swell of the rubber compounds with either processing oil or NS 60 is governed mainly by the state‐of‐mix, but by wall slip in the case of compounds with WB 16. As for the dynamic mechanical properties, the plasticizing effect is the major factor controlling the properties in the case of processing oil, while the degree of crosslink and dilution effect are the main factors in the case of NS 60. Both degree of crosslink and state‐of‐mix are responsible for the dynamic mechanical properties in the case of WB 16. In addition, it was found that the tensile properties are controlled mainly by the plasticizing effect in the case of processing oil, but by the degree of crosslink in the cases of WB 16 and NS 60. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2474–2482, 2001
Selective retention properties to silver(I) and mercury(II) ions of poly(4‐vinylpyridine) methyl iodide studied by the liquid‐phase polymer‐based retention technique
Authors: Rivas B. L. , Pereira E. D.
Published: August 2002

The retention of various metal ions by water‐soluble poly(4‐vinylpyridine) methyl iodide in conjunction with ultrafiltration membrane was investigated. The method is based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molecular weight species from the polymer metal ion complex formed. It is shown that the polychelatogen can bind silver(I) and mercury(II) ions in aqueous solution at pH 1. At higher pH, the water‐soluble polymer can be applied to the separation and preconcentration of silver metal ions. Therefore, this polychelatogen is highly selective to Hg(II) at pH 1 with respect to metal ions such as Cd(II) and Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2578–2582, 2001
Mechanical properties and fracture morphology of Al(OH)3/polypropylene composites modified by PP grafting with acrylic acid
Authors: Mai Kancheng , Li Zhengjun , Qiu Yuxin , Zeng Hanmin
Published: August 2002

Al(OH)3/polypropylene (PP) composites modified by polypropylene grafted with acrylic acid (FPP) were prepared by melt extrusion. Effect of PP grafting with acrylic acid on mechanical properties and fracture morphology of Al(OH)3/polypropylene composites were investigated. Although incorporation of Al(OH)3reduced the mechanical properties of PP, addition of FPP increased the mechanical properties of Al(OH)3/PP composites. It is suggested that addition of FPP improve the dispersion of Al(OH)3and the interfacial interaction between filler and matrix. Mechanical properties of Al(OH)3/FPP/PP composites depend on the grafting rate and the content of FPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2617–2623, 2001
Application of chitosan/nonionic surfactant mixture in reactive dyes for dyeing wool fabrics
Authors: Yen Ming‐Shien
Published: August 2002

The feasibility of wool fabrics pretreated with a chitosan/nonionic surfactant mixture and dyed with reactive dyes was studied. The results showed that the presence of the chitosan/surfactant improved the application to wool, which greatly enhanced the color strength when dyed at 50°C but little change was observed when dyed at 80°C. The higher the concentration of chitosan/surfactant added, the greater was the color strength of the dyed wool fabrics. The amounts found to be optimum for dyeing were 0.5% chitosan and 1.0% surfactant. The washing fastness of the dyed wool fabrics was in the range of grades 4–5, the dry rubbing fastness was in the range of grades 4–5, and the wet rubbing fastness was in the range of grades 3–4. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2859–2864, 2001
Description of PVT behavior of an industrial polypropylene–EPR copolymer in process conditions
Authors: Pantani R. , Titomanlio G.
Published: August 2002

An experimental procedure is presented to describe the PVT behavior of multiphase polymeric materials in a wide range of cooling rates. In particular, the procedure is applied to a typical multiphase industrial polymer, that is, an industrial polypropylene–ethylene‐propylene rubber (iPP–EPR) copolymer with a small percentage of talc. The volume evolution is described combining specific volumes of different phases present in the material. All phases are described simply by thermal expansion and compressibility coefficients drawn either from the literature or from low and high temperature (i.e., below and above the iPP crystallization range) standard PVT data. Crystallization evolution of iPP is described by the Nakamura nonisothermal formulation of the Avrami–Evans crystallization kinetic model. Model parameters are identified by comparison with both standard calorimetric results and final densities of thin samples solidified during quenches conducted with cooling rates of several hundreds of K/s. It is also shown that identification of crystallization kinetic parameters by means of calorimetric data only leads to misleading results for cooling rates larger than those adopted in the calorimetric tests. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 267–278, 2001
Propylene polymerization by using TiCl4 catalyst supported on solvent‐activated Mg(OEt)2
Authors: Kang Kap Ku , Kim Kwang‐Soo , Lee Dong‐Ho , Jeong Young‐Tae
Published: August 2002

Solvent activation of Mg(OEt)2 in ethanol with carbon dioxide was carried out in a 1‐L three‐neck flask under nitrogen atmosphere, to investigate structural changes of Mg(OEt)2 support. During activation of Mg(OEt)2 by ethanol and CO2, a suspension mixture was converted to a clear solution and CO2 was inserted into the MgO bond of Mg(OEt)2, to form magnesium ethyl carbonate. The solid supports were obtained from the removal of solvents by heating, during which CO2 split off from the magnesium ethyl carbonate between 100 and 150°C. The structural changes of the obtained supports and the corresponding catalysts were checked by IR and TGA. The polymerization behavior of propylene with the catalyst and morphology of the obtained polymer were also examined. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 460–467, 2001
Thermal analysis and miscibility of chitin/polycaprolactone blends
Authors: Yang Anle , Wu Renjie , Zhu Pinfang
Published: August 2002

Chitin/polycaprolactone (PCL) blends were prepared by melt‐blending of chitin and PCL with varying amounts of chitin. Thermal analysis of DSC, DMTA, and FTIR were used to characterize the blends. Results showed that increases in the amount of chitin did not cause a decrease in either the melting point or the crystallization point of PCL. The loss‐modulus curve did not show a change of glass‐transition temperature (Tg) from a dynamic temperature ramp test, which revealed that the pure chitin/PCL blend was not miscible at any ratio. When chitin n‐butyrate (CB) was partly substituted for chitin in the blend, both the melting point and crystallization point of the PCL component was depressed, which implied an improvement of the miscibility of the blend. Furthermore, FTIR characterization suggested an interaction between the components. However, Tg did not change compared to that of the pure PCL in the loss‐modulus curve, that is to say, that the modification of the miscibility by the introduction of CB to the blend lay only in the interfacial region, although not at the molecular level. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3117–3123, 2001
Swelling and electrical properties of rubber vulcanizates loaded with paraffin wax
Authors: Abu‐Abdeen M. , Ghani S. A. Abdel
Published: August 2002

The influence of the concentration of paraffin wax on the penetration rate, P, and the average diffusion coefficient, D, of kerosene in an SBR–NR composite and also on the coefficient of viscosity were investigated. All decreased with the addition of wax. Also, the effect of the concentration of paraffin wax on both the current–voltage characteristics and the temperature dependence of the dc electrical conductivity were studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3169–3177, 2001