bluuebunny/crossref_metadata_2025 huggingface dataset:
What is the most cost‐effective way to identify silica problem worksites?
Authors: Rosenman Kenneth D. , Hogan Andrew , Reilly Mary Jo
Published: August 2002

Background

State based surveillance systems to identify cases of silicosis have been developed over the past 18 years to target worksite interventions to reduce the incidence of silicosis. Using data from the Michigan silicosis surveillance system, we conducted an analysis to determine the most cost‐effective way to identify problem worksites.

Methods

The initial reporting source of all 470 confirmed cases of silicosis reported to the Michigan surveillance system from 1989 to 1995 was identified. The cost of identifying confirmed cases, worksites, problem worksites, silica problem worksites, and the number of current silica‐exposed workers was determined for four reporting sources: hospitals; physicians; workers' compensations; and death certificates.

Results

Hospital reports were the first to identify 67% of the confirmed cases, 74% of the worksites, and 58% of the problem worksites. Physician reports initially identified 17% of confirmed cases, 15% of worksites, and 26% of problem worksites. Workers' compensation records initially identified 11% of confirmed cases, 4% of worksites, and 8% of problem worksites. Death certificates initially identified 5% of confirmed cases, 7% of worksites, and 8% of problem worksites. Hospital reports were the most cost‐effective way to identify cases (US$ 143), worksites (US$ 313), and problem worksites (US$ 454).

Conclusions

Hospital discharge records identified the greatest number of confirmed cases and problem worksites and was the most cost‐effective approach to identify both individuals with silicosis and worksites with problems. Am. J. Ind. Med. 39:629–635, 2001. © 2001 Wiley‐Liss, Inc.
Relationship between health services outcomes and social and economic outcomes in workplace injury and disease: Data sources and methods*
Authors: Mustard Cam , Hertzman Clyde
Published: August 2002

Background

Understanding the mediating role of health care in mitigating social, economic and occupational role disability is a complex task.

Methods

No single method of research will be successful in addressing all elements of this NORA research priority area. In this paper, we argue that research methods are needed which have the following components: (1) the detailed measurement of therapeutic intervention and the impacts of this intervention on clinical and functional health status using study designs which rule out competing explanations, (2) a longitudinal follow‐up component which measures social, economic, and occupational role function following the conclusion of therapy, and (3) a commitment to execute studies across multiple settings to observe the variations in health care and in social and occupational role function that arise as a result of differences in labor market factors and employer and government policies.

Conclusions

More comprehensive portraits of the longitudinal trajectory of individual workers, social, economic and occupational role function following an occupational injury or illness will have significance for a large number of policy sectors. Am. J. Ind. Med. 40:335–343, 2001. © 2001 Wiley‐Liss, Inc.
Valuing the economic consequences of work injury and illness: A comparison of methods and findings
Authors: Weil David
Published: August 2002

Background

Workplace injuries and fatalities in the US create significant economic costs to society. Although economic costs should measure the opportunity cost to society arising from injuries and fatalities, estimating them often proves difficult as a practical matter. This leads to a range of estimates for valuing these costs.

Methods

This paper compares methods of economic valuation, focusing in particular on how different methods diverge to varying degrees from measuring the “true” economic costs of injuries and illnesses. In so doing, it surveys the literature that has arisen in the past 25 years to measure different aspects of economic consequences.

Results

Estimates of the costs of injuries and fatalities tend to understate the true economic costs from a social welfare perspective, particularly in how they account for occupational fatalities and losses arising from work disabilities.

Conclusion

Although data availability often makes estimation of social welfare costs difficult, researchers should attempt to more fully integrate such approaches into estimation procedures and interpretation of their results. Am. J. Ind. Med. 40:418–437, 2001. © 2001 Wiley‐Liss, Inc.
Behavioral phenotypic variation in autism multiplex families: Evidence for a continuous severity gradient
Authors: Spiker Donna , Lotspeich Linda J. , Dimiceli Sue , Myers Richard M. , Risch Neil
Published: August 2002

Recent genetic investigations of autism have studied multiplex families, typically including families with multiple siblings who meet criteria for a diagnosis of autism. However, little is known about the specific behavioral characteristics of siblings with autism in these multiplex families. We investigated the behavioral phenotypic variability and similarity of 351 siblings with autism in 171 multiplex families using cluster analysis and correlations. The results of cluster analyses showed that the individuals with autism could be characterized on a severity gradient: a continuum based on severity of symptoms and impairment as measured by Autism Diagnostic Interview–Revised (ADI‐R) scores, verbal‐nonverbal status, and nonverbal IQ scores. Clusters based on scores from the ADI‐R for the autism diagnostic criteria of the DSM‐IV and nonverbal IQ scores still represented a severity gradient when the effects of verbal‐nonverbal status were removed. The severity gradient was shown to be heritable, with a sib correlation of 30% or a heritability of 60%. In summary, in a sample of 171 autism multiplex families, there was no evidence of discrete behaviorally defined subgroups of affected individuals or families characterized by distinct patterns of behavioral symptoms. Rather, the clusters could be characterized along a single, heritable, continuous severity dimension. © 2002 Wiley‐Liss, Inc.
Family‐based and population study of a functional promoter‐region monoamine oxidase A polymorphism in autism: Possible association with IQ
Authors: Yirmiya Nurit , Pilowsky Tammy , Tidhar Sigal , Nemanov Lubov , Altmark Larissa , Ebstein Richard P.
Published: August 2002

Although the etiology of autism remains to be elucidated, genetic elements significantly contribute to this disorder, and genes on the X chromosome are of special interest because there is a 4:1 predominance of male probands in autism. In the current study, we therefore examined, using the robust transmission disequilibrium test (TDT), possible preferential transmission of variants of a functional monoamine oxidase A (MAO A) promoter region polymorphism for linkage to autism. In the 49 families examined (33 families with one proband and 15 families with two affected siblings), we did not find preferential transmission of MAO A from 33 heterozygous mothers to affected child (TDT chi‐square = 0.29, NS). Nor was any significant difference in MAO A allele frequency observed between 43 male autism subjects versus a group of 108 non‐autism control subjects (chi‐square = 1.23, P = 0.27, NS). However, a trend was observed for an association between IQ in the probands and the MAO A genotype that just attained significance (F = 3.5, P = 0.046, N = 28) in the small group of autism subjects recruited from families with two affected siblings. © 2002 Wiley‐Liss, Inc.
Identification of de novo chromosome rearrangements: Five cases analyzed with differential chromosome painting
Authors: Ida Tomoko , Harada Naoki , Abe Kyōko , Kondoh Tatsuro , Yoshinaga Muneyoshi , Maki Takashi , Niikawa Norio
Published: August 2002

We report on five cases of de novo structural chromosome rearrangements that were difficult to identify by conventional G‐banding analysis. In all five cases, differential chromosome painting (DCP) provided evidence for the presence of an additional segment and its origin. A combination of DCP with subsequent conventional fluorescence in situ hybridization (FISH) analysis using adequate locus‐specific probes and reexamination of G‐banding patterns resulted in successful identification of the rearrangements. Their karyotypes were finally interpreted as 46,XY,der(1)(qter → q42.1::p36.3 → qter) in case 1; 46,XY,der(8)(8pter → 8q24.3::8q24.3 → 8q23.2::?p11.2 → ?ps) in case 2; 47,XY,+der(10)(pter → q11) in case 3; 46,XX,der(3)(17pter → 17p11.2::3p26 → 3qter) in case 4; and 46,XY,dup(1) (pter → q32::q25 → qter) in case 5. © 2002 Wiley‐Liss, Inc.
Evidence supporting WNT2 as an autism susceptibility gene
Authors: Wassink Thomas H. , Piven Joseph , Vieland Veronica J. , Huang Jian , Swiderski Ruth E. , Pietila Jennifer , Braun Terry , Beck Gretel , Folstein Susan E. , Haines Jonathon L. , Sheffield Val C.
Published: August 2002

We examined WNT2 as a candidate disease gene for autism for the following reasons. First, the WNT family of genes influences the development of numerous organs and systems, including the central nervous system. Second, WNT2 is located in the region of chromosome 7q31–33 linked to autism and is adjacent to a chromosomal breakpoint in an individual with autism. Third, a mouse knockout of Dvl1, a member of a gene family essential for the function of the WNT pathway, exhibits a behavioral phenotype characterized primarily by diminished social interaction. We screened the WNT2 coding sequence for mutations in a large number of autistic probands and found two families containing nonconservative coding sequence variants that segregated with autism in those families. We also identified linkage disequilibrium (LD) between a WNT2 3′UTR SNP and our sample of autism‐affected sibling pair (ASP) families and trios. The LD arose almost exclusively from a subgroup of our ASP families defined by the presence of severe language abnormalities and was also found to be associated with the evidence for linkage to 7q from our previously published genomewide linkage screen. Furthermore, expression analysis demonstrated WNT2 expression in the human thalamus. Based on these findings, we hypothesize that rare mutations occur in the WNT2 gene that significantly increase susceptibility to autism even when present in single copies, while a more common WNT2 allele (or alleles) not yet identified may exist that contributes to the disorder to a lesser degree. © 2001 Wiley‐Liss, Inc.
Mitochondrial DNA haplogroups in Amerindian populations from the Gran Chaco
Authors: Demarchi Darío A. , Panzetta‐Dutari Graciela M. , Motran Cristina C. , De Los Angeles López De Basualdo María , Marcellino Alberto J.
Published: August 2002

Mitochondrial DNA from 141 individuals was typed for diagnostic restriction sites and the 9‐bp region V deletion to examine the distribution of the founding mtDNA lineage haplotypes in three Amerindian populations (Mataco, Toba, and Pilagá) who currently inhabit the Argentinian part of the Gran Chaco.

All four lineages were identified in the three tribes and four population samples studied. Disregarding ethnic or geographic origin, haplogroups B and D exhibit high incidence among the Gran Chaco inhabitants, whereas haplogroups A and C are present in a lower frequency. Three individuals possess none of the characteristic markers and, therefore, could not be assigned to one of those lineages.

A neighbor‐joining representation of FST distances reflects the current geographic location of the populations, and this also corresponds to their historic distribution. After separating South America into four major regions (Tropical Forest, Andes, Gran Chaco, and Patagonia‐Tierra del Fuego), the Gran Chaco populations present the highest average intragroup variability (Hs = 0.64) as well as the lowest intergroup diversity (G′ST = 0.06). These findings suggest high levels of gene flow among the Chaco tribes, as well as with neighbor populations from outside the region. Am J Phys Anthropol 115:199–203, 2001. © 2001 Wiley‐Liss, Inc.
Craniodental variation in Paranthropus boisei: A developmental and functional perspective
Authors: Wood Bernard , Lieberman Daniel E.
Published: August 2002

What levels and patterns of craniodental variation among a fossil hypodigm are necessary to reject the null hypothesis that only a single species is sampled? We suggest how developmental and functional criteria can be used to predict where in the skeleton of fossil hominins we should expect more, or less, within‐species variation. We present and test three hypotheses about the factors contributing to craniodental variation in extant primate taxa, and then apply these results to the interpretation of the P. boisei hypodigm. Within the comparative samples of extant Homo, Pan, Gorilla, Pongo, and Colobus, variables from the cranial base, neurocranium, and face that are not subject to high magnitudes of strain have consistently lower levels of intraspecific variation than variables from regions of the face subject to high levels of strain. Dental size variables are intermediate in terms of their reliability. P. boisei is found to have a low degree of variability relative to extant primates for variables shown to be generally useful for testing taxonomic hypotheses. Contrary to the claims of Suwa et al. ([1997] Nature 389:489–492), the recently discovered material from Konso falls within the range of variation of the “pre‐Konso” hypodigm of P. boisei for available conventional metrical variables. Those aspects of the Konso material that appear to extend the range of the P. boisei hypodigm involve regions of the skull predicted to be prone to high levels of within‐species variation. The approach used in this study focuses on craniodental data, but it is applicable to other regions of the skeleton. Am J Phys Anthropol 116:13–25, 2001. © 2001 Wiley‐Liss, Inc.
Enamel hypoplasia in the deciduous teeth of great apes: Variation in prevalence and timing of defects
Authors: Lukacs John R.
Published: August 2002

The prevalence of enamel hypoplasia in the deciduous teeth of great apes has the potential to reveal episodes of physiological stress in early stages of ontogenetic development. However, little is known about enamel defects of deciduous teeth in great apes. Unresolved questions addressed in this study are: Do hypoplastic enamel defects occur with equal frequency in different groups of great apes? Are enamel hypoplasias more prevalent in the deciduous teeth of male or female apes? During what phase of dental development do enamel defects tend to form? And, what part of the dental crown is most commonly affected?

To answer these questions, infant and juvenile skulls of two sympatric genera of great apes (Gorilla and Pan) were examined for dental enamel hypoplasias. Specimens from the Powell‐Cotton Museum (Quex Park, UK; n = 107) are reported here, and compared with prior findings based on my examination of juvenile apes at the Cleveland Museum of Natural History (Hamman‐Todd Collection; n = 100) and Smithsonian Institution (National Museum of Natural History; n = 36). All deciduous teeth were examined by the author with a ×10 hand lens, in oblique incandescent light. Defects were classified using Fédération Dentaire International (FDI)/Defects of Dental Enamel (DDE) standards; defect size and location on the tooth crown were measured and marked on dental outline charts.

Enamel defects of ape deciduous teeth are most common on the labial surface of canine teeth. While deciduous incisor and molar teeth consistently exhibit similar defects with prevalences of ∼10%, canines average between 70–75%. Position of enamel defects on the canine crown was analyzed by dividing it into three zones (apical, middle, and cervical) and calculating defect prevalence by zone. Among gorillas, enamel hypoplasia prevalence increases progressively from the apical zone (low) to the middle zone to the cervical zone (highest), in both maxillary and mandibular canine teeth.

Results from all three study collections reveal that among the great apes, gorillas (87–92%) and orangutans (91%) have a significantly higher prevalence of canine enamel defects than chimpanzees (22–48%). Sex differences in canine enamel hypoplasia are small and not statistically significant in any great ape. Factors influencing intergroup variation in prevalence of enamel defects and their distribution on the canine crown, including physiological stress and interspecific dento‐gnathic morphological variation, are evaluated. Am J Phys Anthropol 116:199–208, 2001. © 2001 Wiley‐Liss, Inc.
Some characteristics of arsenate transport in a marine cyanobacterium, Synechococcus sp.
Authors: Takahashi Akira , Kawakami Hidekazu , Iwakiri Katsuyuki , Matsuto Shigeki
Published: August 2002

The mechanism of arsenate incorporation in the cells of a unicellular marine cyanobacterium, Synechococcus sp., was investigated. A lag period in arsenate incorporation, probably caused by an inhibitory effect of phosphate absorbed on the cell surface, was observed. Although arsenate incorporation into the cells of cyanobacterium was several times faster than that of phosphate, it was readily inhibited by addition of phosphate, also suggesting inhibition caused by phosphate. The Michaelis–Menten type of equation was employed for the simulation of incorporation, and a nonlinear fitting was applied for the estimation of the kinetic parameters in the equation. Analysis based on the assumption that arsenate is incorporated via the phosphate transport system in cells suggested that arsenate competes with phosphate for entry into cells and each species acts as a competitive inhibitor to each other. The affinity of arsenate with the transport system was much less than that of phosphate, but it was not low enough for elucidation of an almost complete inhibition of arsenate incorporation by phosphate, and another mechanism to block the approach of arsenate to the transport system was deduced to exist. The inhibitory effect of phosphate on arsenate incorporation seemed responsible for alleviation of the toxicity of arsenate in the cells. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis, and structural and morphological characterization of iron oxide–ion‐exchange resin and –cellulose nanocomposites
Authors: Suber Lorenza , Foglia Sabrina , Maria Ingo Gabriel , Boukos Nikos
Published: August 2002

The synthesis and the comparative structural and morphological study of iron oxide nanoparticles in polystyrene‐based ion‐exchange resins and cellulosics are reported. The synthesis of magnetite was performed under nitrogen atmosphere by an in situ method in the presence of the matrix itself. Scanning and transmission electron microscopy measurements led to a detailed characterization of matrix morphology and of magnetic particle structure, size and morphology. The results show that the matrix influences the iron oxide particle size; the average size is about 7 nm in the resins and 25 nm in the celluloses. In the resins, particles are present inside the pores and as aggregates on the surface of the resin beads, whereas in the cellulose they are present on the surface and in the swollen network of the microfibers constituting the single fibers. Copyright © 2001 John Wiley & Sons, Ltd.
Preparation and characterization of PSt‐b‐PHEMA metal hybrids
Authors: Wang Yanmei , Wu Jingshen , Yuan Jinying , Sun Guifen , Pan Caiyuan
Published: August 2002

The block copolymer polystyrene‐b‐poly[2‐(trimethylsilyloxy)ethylene methacrylate] (PSt‐b‐PTMSEMA) was synthesized using atom‐transfer radical polymerization (ATRP). The hydrolysis of PSt‐b‐PTMSEMA led to the formation of an amphiphilic block copolymer, polystyrene‐b‐poly(2‐hydroxylethyl methacrylate) (PSt‐b‐PHEMA), which was characterized by GPC and 1H‐NMR. TEM showed that the PSt‐b‐PHEMA formed a micelle, which is PSt as the core and PHEMA as the shell. Under appropriate conditions, the nickel or cobalt ion cause chemical reactions in these micelles and could be reduced easily. ESCA analysis showed that before reduction the metal existed as a hydroxide; after reduction, the metal existed as an oxide, and the metal content of these materials on the surface is more than that on the surface of the copolymer metal ion. XRD analysis showed that the metal existed as a hydroxide before reduction and existed as a metal after reduction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2883–2891, 2002; DOI 10.1002/app.10278
Effect of recovery methods and conditions on the yield, solubility, molecular weight, and creep compliance of regenerated chitosan
Authors: Chen Rong Huei , Liu Chang Shu
Published: August 2002

The objective of this study is to explore the effect of using different recovery methods and conditions on the yield, solubility, molecular weight, and creep compliance of the regenerated chitosan. The results show that yields obtained by dialysis were higher than those using recovery medium of alkali solutions, organic solvents, or alkali–alcohol–water mixtures. For those chitosans employing alkali solutions as the recovery medium, the higher the alkali concentration used, the higher the yields obtained, although the total quantity of alkali in the solution were the same. Solubilities of regenerated chitosans were similar and independent at the methods of using alkali solution, organic solvent or alkali–alcohol–water mixture or at different concentrations of alkali solution. The molecular weight of regenerated chitosan decreased from 2.37 × 107 to 1.68 × 107 Da proportionally with the concentration of the alkali solution of the recovery medium from 1N to 8N. Creep compliance of regenerated chitosan gel obtained from 65% degree of deacetylation (DD) chitosan was lower than that of either 72 or 89% DD chitosan gel. Of the same DD chitosan, compliance of regenerated chitosan gels obtained by using a higher concentration of alkali solution was lower than that of a lower concentration ones. Hydrogels regenerated from different DD chitosans and/or different recovery mediums have different structure and tactile properties. Therefore, they can be used as wound dressings suited to different applications. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 193–202, 2002; DOI 10.1002/app.10296
Thermal degradation studies of different polar polyethylene copolymers
Authors: Jäger K.‐M. , Dammert R. C. , Sultan B.‐Å.
Published: August 2002

The thermal degradation of different polar polyethylene copolymers, ethylene/methylacrylate (EMA), ethylene/ethylacrylate (EEA), ethylene/butylacrylate (EBA), ethylene/methylmethacrylate (EMMA), and ethylene/hydroxyethylmethacrylate (EHEMA), was studied by using thermogravimetric analysis (TGA), infrared analysis (FTIR), and size exclusion chromatography (SEC). Weight loss measurements of the different copolymers were performed at 333°C by using a nitrogen atmosphere in a TGA instrument. The samples thus aged were then characterized with the help of FTIR and SEC. Degradation reactions, such as ester pyrolysis, chain scission, and gelation, were investigated. EBA, EEA, and EHEMA undergo ester pyrolysis, which is affected by the structure of the ester moiety. EHEMA reacts additionally by transesterification and thus forms crosslinks. EMA and EMMA do not react by ester pyrolysis. It is concluded that the reaction products formed during ester pyrolysis support chain scission, and therefore, these reactions are observed more for EBA and EEA than for EMA and EMMA. Finally, the rate of chain scission is higher for EMMA than for EMA. This is explained as being due to an initiation of chain scission at the α—C—C bond, in which formed radicals are stabilized by the additional methyl group in EMMA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1465–1473, 2002; DOI 10.1002/app.10510
Thermally stimulated creep (TSCr) study of viscoelastic behavior and physical aging of a polymeric matrix composite for spacecraft structures
Authors: Issoupov V. , Demont Ph. , Lacabanne C. , Startsev O. V. , Viel V. , Dinguirard M.
Published: August 2002

Thermally Stimulated Creep (TSCr) mechanical spectroscopy has been used to analyze molecular movements in KMU‐4lcarbon/epoxy composite material around the glass transition temperature. This technique is powerful to characterize the microstructure and micromechanical properties of the epoxy matrix and their evolution upon thermal aging. Three cooperative submodes have been distinguished by resolving the fine structure of the material complex α‐retardation mode. The elementary processes constituting this mode possess activation enthalpies and preexponential factors that strongly depend on the thermal history of the sample. The activation parameters of the composite are subject to perceptible evolution due to postcuring degradation. The α‐mode associated complex spectrum shifts towards higher temperatures by 27°C as a consequence of a series of quenching in the temperature range 260 to 0°C; the material shows a rise in the fragility and a deterioration in the crack‐growth resistance qualities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 342–350, 2002
Polyether‐amide segmented copolymers based on ethylene terephthalamide units of uniform length
Authors: Bouma Krista , Wester Geertje A. , Gaymans Reinoud J.
Published: August 2002

Segmented copolymers were synthesized using the crystallizable bisesterdiamide segment (N,N′‐bis(p‐carbomethoxybenzoyl)ethanediamine) T2T‐dimethyl (a one‐and‐a‐half repeating unit of nylon 2,T) and poly(tetramethyleneoxide) segments. Poly(tetramethyleneoxide) (PTMO) is amorphous and has a low Tg. The segment length was varied from 650 to 2800 g/mol by extending PTMO650 using dimethyl isophthalate. The polymers were synthesized in the melt, and test samples were prepared by injection molding. The melting behavior, as well as the torsion modulus spectrum as a function of temperature, were studied using DSC and DMA, respectively. The T2T‐PTMO polymers were found to have sharp glass (Tg) and flow transitions (Tfl), and the modulus at the rubbery plateau appeared to be virtually temperature independent. The Tg value was found to be independent of the diamide concentration, thus indicating that the T2T segments were fully crystallized. The Tfl was found to decrease with increasing soft segment length; this was ascribed to a “solvent” effect of the amorphous phase of the crystalline T2T units. The difference between the melting and crystallization temperatures was found to be low, thus suggesting that on cooling, there is a high rate of crystallization. When ethanediol was added as a T2T segment extender, amide‐ester‐amide segments were introduced. These amide‐ester‐amide segments form a separate lamellar phase with a much higher melting temperature (>300°C). It was found that the crystallization rate of the T2T units was enhanced by the presence of the amide‐ester‐amide segments, indicating that upon cooling, the crystallized amide‐ester‐amide segments form the nucleation sites for the nonextended T2T segments. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1173–1180, 2001
Effect of talc/MMA in situ polymerization on mechanical properties of PVC‐matrix composites
Authors: Xie X. L. , Li B. G. , Pan Z. R. , Li R. K. Y. , Tjong S. C.
Published: August 2002

In this study, polymethyl methacrylate (PMMA)‐coated talc was produced by the in situ polymerization of methyl methacrylate on the talc surface. The polymerization reaction was performed by both batch and semicontinuous emulsion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated‐talc morphology were systematically investigated. It was found that the talc particles have no effect on the polymerization of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distribution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subsequently used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA‐coated‐talc/PVC composites were studied. Morphological structure of PVC‐matrix composites revealed that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between the talc and PVC. The mechanical properties of the composites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface for optimum toughening. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2105–2112, 2001
Composite materials prepared from waste textile fiber
Authors: Bateman Stuart A. , Wu Dong Yang
Published: August 2002

Composite materials were prepared utilizing whole carpet and LDPE. The addition of compatibilizers during processing was shown to provide an improvement in the mechanical performance of such materials. It is believed that the addition of a reactive compatibilizer to the system increases both the compatibility between components of the composite material and interfacial interactions, through chemical reactions between functional groups on the compatibilizer and the surface of the carpet fibers under the processing conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3178–3185, 2001
Preirradiation grafting polymerization of DMAEMA onto cotton cellulose fabrics
Authors: Jun Lu , Min Yi , Jiuqiang Li , Hongfei Ha
Published: August 2002

The grafting yield of N,N′‐dimethylaminoethyl methacrylate (DMAEMA) on cotton cellulose fabric increased with grafting time, absorbed dose, and concentration of the monomer in the aqueous solution, but decreased with grafting temperature. The dose rate had a small effect on the grafting yield. The optimal grafting yields of DMAEMA on cotton cellulose were rather low, approximately 50% compared with N‐isopropylacrylamide (NIPAAm), although both monomers could be synthesized to be thermally reversible hydrogels. The relationship between the grafting yield and the grafting temperature indicated that the trapped radicals located in the interphases between crystalline and amorphous regions of irradiated samples were the main active species inducing the grafting reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3578–3581, 2001
Interpenetrating polymer networks based on poly(acrylic acid) and gelatin. I: Swelling and thermal behavior
Authors: Burugapalli Krishna , Bhatia Dhiraj , Koul Veena , Choudhary Veena
Published: August 2002

This article describes the synthesis of full and semi‐interpenetrating polymer networks (IPNs) based on poly(acrylic acid) and gelatin as polymers 1 and 2, which were crosslinked sequentially using N,N′‐methylene bisacrylamide (BAm) and glutaraldehyde, respectively. Various samples were prepared by taking varying amounts of acrylic acid and gelatin in the initial feed. Sequential IPNs were prepared by first polymerizing and crosslinking acrylic acid in the presence of gelatin using redox initiators (ammonium persulphate and sodium metabisulphite) and BAm as a crosslinking agent. Gelatin present in the firm gels was then crosslinked using 4% glutaraldehyde. Characterization of these gels was done by measuring their swelling behavior as a function of pH, temperature, and time. Percent swelling increased with increasing amounts of acrylic acid. The swelling ratio was also determined in the pH range of 1 to 12. Acid/alkali or buffers were used for maintaining pH. A significant increase in the percent swelling was observed when pH of distilled water was above 10. On the other hand, in the case of buffer, the swelling ratio increased with increasing the pH, and a maxima was observed at pH 8.4. A further increase in pH resulted in a decrease in the swelling ratio. Thermal and morphological characterization was done using thermogravimetric analyzer and scanning electron microscopy, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 217–227, 2001
Bulk and solution copolymerization of methyl methacrylate and vinyl acetate
Authors: Scorah M. J. , Hua H. , Dubé M. A.
Published: August 2002

A series of batch, bulk and solution (in toluene) copolymerizations of methyl methacrylate and vinyl acetate was performed under various reaction conditions to high monomer conversions. In addition, low conversion bulk experiments were performed to estimate monomer reactivity ratios using the error in variables model method, based on terminal model (Mayo–Lewis) kinetics. A combination of the low and high conversion data with data from a previous study yielded reactivity ratio (r) estimates of 27.465 and 0.0102 for rMMA and rVAc, respectively, using the integrated copolymer composition (Meyer–Lowry) equation. In the high conversion experiments the effects of various factors on the reaction rate, cumulative copolymer composition, number‐ and weight‐average molecular weights, and molecular weight distribution were studied. The factors included the monomer feed composition, initiator concentration, temperature, solvent concentration, and the addition of n‐dodecyl mercaptan chain transfer agent. These factors were examined in light of the wide difference in the monomer reactivity ratios. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1238–1255, 2001
Properties and morphology of poly(ethylene terephthalate) and high‐density polyethylene blends
Authors: Guerrero Carlos , Lozano Tomás , González Virgilio , Arroyo Eliud
Published: August 2002

Blends of poly(ethylene terephthalate) (PET) and high‐density polyethylene (HDPE) with and without a compatibilizing agent were studied. Both materials are widely used in the soft drink bottle industry. The compatibilizing agent was a copolymer of ethylene and methacrylic acid partially neutralized with zinc (Surlyn). The olefinic segment of Surlyn is compatible with HDPE, whereas the Surlyn carboxylic acid groups is affine with the PET carbonyl groups. The effectiveness of the compatibilizing agent was evaluated using different techniques, such as infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1382–1390, 2001
Improved polyimide/metal adhesion by chemical modification approaches
Authors: Ranucci Elisabetta , Sandgren Åsa , Andronova Natalia , Albertsson Ann‐Christine
Published: August 2002

To increase their adhesion to silver, polyimide (PI) surfaces were modified by sulfonation reactions by means of different experimental procedures. The results of these modification reactions were analyzed in terms of the variation of the surface chemical composition examined by X‐ray photoelectron spectroscopy. Long‐time reactions were also followed by monitoring the increase in weight of the PI films. Changes in the total surface free energy were evaluated by contact angle measurements with the sessil drop method. The influence of the modification reactions on silver/PI adhesion was estimated by means of a 180° peeling test according to ASTM standards. Finally, the effect of chemical modification on film roughness was investigated by means of atomic force microscopy. The results obtained showed that a net improvement, that is, over the maximum rate according to the reference ASTM test, was attained via both the gaseous SO3 and concentrated H2SO4 procedures, with the latter procedure more effective in the presence of silver sulfate as a catalyst. However, the former was judged more convenient because of the low amount of reagents used and the simplicity of cleaning operations. Interestingly, optimum adhesion levels were attained after only very low contact times with all sulfonating agents, that is, after about 30 s. These results were compared with the effects on PI/silver adhesion of traditional etching procedures with KOH aqueous solutions at different temperatures. In this case, good adhesion was observed only after longer reaction times, that is, on the order of 1–2 min in the case of 1M KOH and 1 h in the case of 0.1M KOH. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1971–1985, 2001
Water‐soluble esters of biosynthetic poly(γ‐glutamic acid)
Authors: Pérez–Camero Graciela , Vázquez Blanca , Muñoz–Guerra Sebastián
Published: August 2002

Water‐soluble poly(γ‐glutamic acid) (PGGA) esters were prepared by transesterification of poly(α‐methyl‐γ‐glutamate) with mono‐, di‐, and triethylene glycols with one hydroxyl end group blocked as methyl ether. Only the monoglycol appeared to be crystalline with melting at 160°C, and glass‐transition temperatures were found to increase from 10 to 60°C with the length of the oxyethylene side chain. All these poly(γ‐glutamate)s are stable up to temperatures near 250°C. Moisture sorption, surface wettability, and hydrodegradability were evaluated as a function of time. It was found that in overall sensitivity to water increased with the glycol chain length but the behavior at short contact times was critically affected by conformational factors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2027–2036, 2001
Structure and reaction mechanism for the monoacid diol polyester from caprolactone and 2,2′‐bis(hydroxymethyl)propionic acid: NMR and melting‐point evidence
Authors: Simms J. A. , McCord E. F.
Published: August 2002

The product distribution in the synthesis of acidic hydroxypolyesters from a 6/1 mol ratio of caprolactone and 2,2′‐bis(hydroxymethyl)propionic acid (DMPA) changes with reaction time and temperature. 13C‐nuclear magnetic resonance (NMR) signals were identified that are specific for all the possible substitution products around the quaternary carbon in the DMPA. This allows quantitative determination of the six different species that are present. NMR studies showed that over one‐half of the product is substituted on only one of the DMPA hydroxyls. The residual DMPA concentration increases at times and temperatures higher than those required to just complete caprolactone conversion because of equilibration of the kinetic product. All process conditions produced polyesters with two melting points. This suggests that the monosubstituted and disubstituted families of oligomers which are present are not completely miscible with one another. Polyester melting points increase as reaction time and temperature increase. This indicates that the degree of polymerization of the polycaprolactone arms increases as the severity of the preparative condition increases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2217–2226, 2001
Reexamination of the miscibility of stereoregular poly(methyl methacrylate) with poly(vinyl phenol)
Authors: Hsu Wen‐Ping
Published: August 2002

Previously, isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMAs) (designated as iPMMA, aPMMA, and sPMMA) were mixed with poly(vinyl phenol) (PVPh) separately in tetrahydrofuran (THF) to make three polymer blend systems. According to calorimetry data, iPMMA was found to be miscible with PVPh; however, partial miscibility or immiscibility was found between aPMMA (or sPMMA) and PVPh. According to the article by C. J. T. Landry and D. M. Teegarden, Macromolecules, 1991, 24, 4310, THF is the reason for causing aPMMA and PVPh to phase separate, but 2‐butanone instead produces miscible blends. Therefore, in this article these three polymer systems were investigated again using 2‐butanone as solvent. Films were prepared under specific conditions to minimize the effect of aggregation in PMMA. The formation of hydrogen bonding between PMMA and PVPh and the attendant changes in the aggregation of PMMA segments were determined in the solid states by means of FTIR. Based on the results of calorimetry, iPMMA and aPMMA were found to be miscible with PVPh. For iPMMA/PVPh blends, different degrees of hydrogen bonding were observed based on DSC data and FTIR spectra when compared to previous study. An elevation of the glass transition temperatures (Tgs) of aPMMA/PVPh blends above weight average was detected and the Tg values were fitted well by the Kwei equation. But partial miscibility was still found between sPMMA and PVPh on account of the observation of two Tgs in most compositions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1425–1431, 2002
A comparative study of gut‐associated lymphoid tissue in calf and chicken
Authors: Yasuda Masahiro , Tanaka Shogo , Arakawa Hiroshi , Taura Yasuho , Yokomizo Yuichi , Ekino Shigeo
Published: August 2002

The calf contains two types of Peyer's patches (PPs): jejunal and ileal. The ileal PP has been thought to be equivalent to the bursa of Fabricius (BF) as a central lymphoid organ. The morphologies of ileal and jejunal PPs in the calf were compared with those of the BF and the caecal tonsil (CT) in the chicken. Immunoglobulin G–positive (IgG+) cells appear in the follicles of them all and exhibited a dendritic appearance after birth. We investigated whether the IgG in these follicles was produced in situ. IgG‐producing cells were detected in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. CD4+ cells were distributed in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. The data suggest that Ig class switching occurs in both jejunal PP follicles and CT follicles, but does not occur in either the ileal PP follicles or the bursal follicles. Because CD4+ T cells would be prerequisite for Ig class switching in these follicles, IgG+ cells of the follicular medullas in the ileal PP and the BF would trap immune complexes from the gut lumen. The primary B‐cell repertoire might be selected by gut‐derived antigens in the ileal PP and the BF before seeding the periphery. Anat Rec 266:207–217, 2002. © 2002 Wiley‐Liss, Inc.
Reparative myogenesis in long‐term denervated skeletal muscles of adult rats results in a reduction of the satellite cell population
Authors: Dedkov Eduard I. , Kostrominova Tatiana Y. , Borisov Andrei B. , Carlson Bruce M.
Published: August 2002

This study, conducted on 25‐month denervated rat hindlimb muscles, was directed toward elucidating the basis for the poor regeneration that is observed in long‐term denervated muscles. Despite a ∼97.6% loss in mean cross‐sectional area of muscle fibers, the muscles retained their fascicular arrangement, with the fascicles containing ∼1.5 times more fibers than age‐matched control muscles. At least three distinct types of muscle fibers were observed: degenerating, persisting (original), and newly formed (regenerated) fibers. A majority of newly formed fibers did not appear to undergo complete maturation, and morphologically they resembled myotubes. Sites of former motor end‐plates remained identifiable in persisting muscle fibers. Nuclear death was seen in all types of muscle fibers, especially in degenerating fibers. Nevertheless, the severely atrophic skeletal muscles continued to express developmentally and functionally important proteins, such as MyoD, myogenin, adult and embryonic subunits of the nicotinic acetylcholine receptor, and neural‐cell adhesion molecule. Despite the prolonged period of denervation, slow and fast types of myosin were found in surviving muscle fibers. The number of satellite cells was significantly reduced in long‐term denervated muscles, as compared with age‐matched control muscles. In 25‐month denervated muscle, satellite cells were only attached to persisting muscle fibers, but were never seen on newly formed fibers. Our data suggest that the absence of satellite cells in a population of immature newly formed muscle fibers that has arisen as a result of continuous reparative myogenesis may be a crucial, although not necessarily the only, factor underlying the poor regenerative ability of long‐term denervated muscle. Anat Rec 263:139–154, 2001. © 2001 Wiley‐Liss, Inc.
Interaction between heat‐shock protein 73 and HLA–DRB1 alleles associated or not with rheumatoid arthritis
Authors: Auger Isabelle , Lepecuchel Lydia , Roudier Jean
Published: August 2002

Objective

HLA–DRB1 alleles whose third hypervariable region contains a QKRAA/QRRAA/RRRAA motif are associated with rheumatoid arthritis (RA) through unknown mechanisms. We previously demonstrated that the QKRAA motif was also expressed on the Escherichia coli 40‐kd heat‐shock protein (HSP) DnaJ. The QKRAA motif helps DnaJ bind its partner chaperone, the E coli 70‐kd HSP DnaK. Furthermore, we observed that in lymphoblastoid cells, Hsp73, the constitutive 70‐kd HSP, associates with HLA–DRB1*0401 (an allele with a QKRAA motif) and targets it to lysosomes. In this study, we sought to classify different HLA–DRB1 alleles according to their ability to bind Hsp73.

Methods

To evaluate how well different HLA–DRB1 alleles could bind Hsp73, we developed a quantitative precipitation assay and a direct binding assay.

Results

Quantitative precipitation assay from total cellular proteins and from lysosomal extracts demonstrated that RA‐associated HLA–DRB1 alleles bound Hsp73 better than did HLA–DRB1 alleles that were not associated with RA. HLA–DRB1*0401 was the best Hsp73 binder. These findings were confirmed by direct binding assay between purified proteins.

Conclusion

HLA–DRB1*0401 was the best Hsp73 binder among the 8 different HLA–DRB1 alleles that were tested.
Pharmacokinetics and tissue distribution of the anticholinergics tiotropium and ipratropium in the rat and dog
Authors: Leusch A. , Eichhorn B. , Müller G. , Rominger K.‐L.
Published: August 2002

Ipratropium, a current treatment for chronic obstructive pulmonary disease (COPD) and tiotropium, a longer acting anticholinergic bronchodilator currently being developed for COPD are structurally related to atropine. In this study, the intravenous (i.v.), oral (p.o.) and intratracheal (i.tr.) single dose pharmacokinetics (PK) of tiotropium and ipratropium were determined in rat and dog. In rats, concentration–time profiles of tiotropium and ipratropium after single i.v. bolus administration of 7–8 mg kg−1 are similar. Both drugs are highly cleared (Cl between 87 and 150 ml min−1 kg−1) and extensively distributed into tissues (volume of distribution Vss between 3 and 15 l kg−1). In dogs, this holds also true for both drugs (Cl between 34 and 42 ml min−1 kg−1, Vss between 2 and 10 l kg−1), although different dose regimen were applied (i.v. bolus of 0.08 mg kg−1 vs. infusion of 0.1 mg kg−1 h−1 for 3 h). Tiotropium plasma concentrations increased linearly in rats over a wide dose range following single i.v. administration. Both ipratropium and tiotropium showed a comparable terminal elimination half‐life in rat urine (21–24 h) after single i.v. administration, which was much longer than the corresponding half‐life in plasma (6–8 h). Whole body autoradiography in rats revealed a broad and rapid tissue distribution of [14C]tiotropium radioactivity after single i.v. administration. A comparable distribution pattern has also been reported earlier for ipratropium. Copyright © 2001 John Wiley & Sons, Ltd.