bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence of cigarette smoking by occupation and industry in the United States*
Authors: Bang Ki Moon , Kim Jay H.
Published: August 2002

Background

This study was undertaken to estimate the most recent prevalence of cigarette smoking by occupation and industry in the US, using the data from the third National Health and Nutrition Examination Survey (NHANES III), 1988–1994.

Methods

Included in NHANES III are data on the cigarette smoking status, occupation, industry, and other demographic information of US non‐institutionalized civilians obtained through household interview surveys. The study population included 20,032 adults aged 17 years and older. To estimate the prevalence of cigarette smoking across occupation and industry groups, we used the Survey Data Analysis (SUDAAN) software.

Results

The prevalence of cigarette smoking was highest among material moving occupations, construction laborers, and vehicle mechanics and repairers. The lowest smoking prevalence was found among teachers. Among industry groups, the construction industry had the highest prevalence of cigarette smoking.

Conclusions

These findings provide information useful for targeting education activities focusing on adverse health effects of cigarette smoking and also for indirect adjustments in analysis of morbidity and mortality by occupation. Am. J. Ind. Med. 40:233–239, 2001. Published 2001 Wiley‐Liss, Inc.
Craniofacial phenotypes in segmentally trisomic mouse models for Down syndrome
Authors: Richtsmeier Joan T. , Zumwalt Ann , Carlson Elaine J. , Epstein Charles J. , Reeves Roger H.
Published: August 2002

Trisomy for chromosome 21 (Chr 21) has profound effects on development that result in a constellation of phenotypes known as Down syndrome (DS). Distinctive craniofacial manifestations are among the few features common to all individuals with DS. The characteristic face of a person with DS results primarily from maldevelopment of the underlying craniofacial skeleton. The Ts65Dn mouse, which has segmental trisomy 16, producing dosage imbalance for about half the genes found on human Chr 21, exhibits specific skeletal malformations corresponding directly to the craniofacial dysmorphogenesis in DS. Here we demonstrate that Ts1Cje mice, which are at dosage imbalance for about 3/4 of the genes triplicated in Ts65Dn, demonstrate a very similar pattern of anomalies in the craniofacial skeleton. However, one characteristic of Ts65Dn mice, a broadening of the cranial vault contributing to brachycephaly, is not seen in Ts1Cje mice. These observations independently confirm that a dosage imbalance for mouse genes orthologous to those on human Chr 21 has corresponding effects in both species. The subtle differences in the craniofacial phenotypes of Ts1Cje and Ts65Dn mice have implications for elucidation of the mechanisms by which this aneuploidy disrupts development. © 2001 Wiley‐Liss, Inc.
Serum leptin levels and anthropometric correlates in Ache Amerindians of eastern Paraguay
Authors: Bribiescas Richard G.
Published: August 2002

Leptin is a recently discovered peptide hormone secreted primarily from adipocytes in humans and other mammals; it is a reflection of fat stores, and has been associated with reproductive function. However, few leptin measurements are available from nonindustrialized populations, including contemporary hunter/gatherer communities undergoing the transition to sedentary agriculture. This investigation reports single‐sample serum leptin measurements in healthy Ache Amerindian males (n = 21; average age, 32.8 ± 3.4 SE) and females (n = 12; average age, 31.3 ± 4.3) in eastern Paraguay. Ache leptin concentrations were much lower than in industrialized populations, although significant sexual dimorphism was evident (female 5.64 ng/ml ± 0.91 SE vs. male 1.13 ng/ml ± 0.08; P < 0.0001). Indeed, female leptin levels were similar to those of anorexic women, despite apparently adequate adiposity. Controlling for fat percentage, no significant sex difference was evident, suggesting that adiposity was the primary source of leptin variation. Body fat percentage was highly correlated with leptin in females (r2 = 0.72; P < 0.0005) but not males, who exhibited a modest negative correlation (r2 = 0.25; P < 0.03). Weight (r2 = 0.45; P = 0.02) and BMI (kg/m2) (r2 = 0.81; P < 0.0001) were also significantly correlated in females but not males. These results suggest that: 1) clinical leptin norms based on industrialized populations may represent the highest range of human variation and may not be representative of most human populations; 2) hormonal priming may underlie population variation in leptin profiles; and 3) the relative importance of leptin as a proximate mechanism regulating reproductive effort during human evolution may have been modest. Am J Phys Anthropol 115:297–303, 2001. © 2001 Wiley‐Liss, Inc.
Simple method for developing percentile growth curves for height and weight
Authors: Ward Richard , Schlenker Janet , Anderson Gregory S.
Published: August 2002

The present paper demonstrates the ease of use of method I by Preece and Baine ([1978] Ann Hum Biol 5:1–24) in generating smoothed growth curves for both height and weight. Using the National Center for Health Statistics (NCHS) growth curve data, smoothed curves were developed and compared to those produced using the least‐squares‐cubic‐spline method. Based on the lower sum of squares and better fit of shape as indicated by residual examination, it was concluded that the method I curve fitting procedure by Preece and Baine ([1978] Ann Hum Biol 5:1–24) fit centile growth curves for height and weight in 2–18‐year‐old male and female children as well as, if not better than, the least‐squares‐cubic‐spline method used in developing the 1979 NCHS growth curves. Further, as this paper demonstrates, smoothed curves can be generated on a desktop computer using readily available software (the SOLVER function within Microsoft EXCEL). Am J Phys Anthropol 116:246–250, 2001. © 2001 Wiley‐Liss, Inc.
Parahippocampal tau pathology in healthy aging, mild cognitive impairment, and early Alzheimer's disease
Authors: Mitchell Thomas W. , Mufson Elliott J. , Schneider Julie A. , Cochran Elizabeth J. , Nissanov Jonathan , Han Li‐Ying , Bienias Julia L. , Lee Virginia M.‐Y. , Trojanowski John Q. , Bennett David A. , Arnold Steven E.
Published: August 2002

Abnormally phosphorylated tau accumulates as neurofibrillary tangles and neuropil threads in older persons with and without Alzheimer's disease. The relationship between neurofibrillary tangles and neuropil threads and how they relate to cognitive function is unknown. This study investigated the relationship between phosphorylated tau lesions and cognitive function in 31 persons participating in the Religious Orders Study, a prospective, longitudinal clinicopathological study of aging and Alzheimer's disease. All subjects underwent detailed neuropsychological performance testing within a year of death and evidenced a spectrum of cognitive performance ranging from normal abilities to mild dementia. Measures of neurofibrillary tangle density and phosphorylated tau immunoreactive structures (predominantly neuropil threads) in the entorhinal and perirhinal cortices by quantitative image analysis were significantly correlated (r = 0.5). In multiple linear regression analyses controlling for age, sex, and education, parahippocampal neurofibrillary tangles and neuropil threads were significantly lower in persons without cognitive impairment compared to those with mild cognitive impairment and/or Alzheimer's disease. Further, neurofibrillary tangles were significantly correlated to measures of episodic memory but not other cognitive abilities; neuropil tangles were not significantly related to memory or other cognitive functions. These data indicate that phosphorylated tau pathology in the ventromedial temporal lobe develop prior to the onset of clinical dementia and their presence is associated with cognitive impairment, particularly impairment of episodic memory.
Novel locus for autosomal dominant pure hereditary spastic paraplegia (SPG19) maps to chromosome 9q33–q34
Authors: Valente Enza Maria , Brancati Francesco , Caputo Viviana , Bertini Enrico , Patrono Clarice , Costanti Danilo , Dallapiccola Bruno
Published: August 2002

Hereditary spastic paraplegia is a clinically and genetically heterogeneous disorder characterized by progressive spasticity of the lower limbs. Seven loci for autosomal dominant pure hereditary spastic paraplegia (ADPHSP) have already been mapped on chromosomes 14q, 2p, 15q, 8p, 12q, 19q, and 2q. We report on an Italian family affected by ADPHSP for which we excluded linkage with the known loci and performed a genome‐wide search. Linkage analysis and haplotype construction permitted the identification of a novel ADPHSP locus on the long arm of chromosome 9, designated SPG19. The phenotype was characterized by late onset (range, 36–55 years) and mild disability, with only 1 patient bound to a wheelchair after 31 years of disease. Urinary disturbances (urgency and/or incontinence) were always present, even in young patients with a short disease history.
High‐density polyethylene/carbon black conductive composites. I. Effect of CB surface modification on its resistivity–temperature behavior
Authors: Zhang Jian‐Feng , Zheng Qiang , Yang Yi‐Quan , Yi Xiao‐Su
Published: August 2002

The effect of the interaction between a polymeric matrix and conductive particles of carbon black (CB), especially the interaction enhanced by oxidizing CB (o‐CB), on the resistivity–temperature behavior of its composites was studied. The results reveal that the interaction between ethylene‐vinyl‐acetate and CB is stronger than that between high‐density polyethylene and CB. The room temperature resistivity of the o‐CB filled system subsequent to thermal cycles increases to a lower extent in comparison with those filled with virgin CB. Moreover, the resistivity decrease of composites filled with o‐CB needs a longer time than that of the virgin CB filled system during isothermal annealing, meaning that the resistivity–temperature behavior of the former is much more stable than that of the latter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3112–3116, 2002; DOI 10.1002/app.10049
Thermal analysis of solution copolymers of styrene with N‐phenylmaleimide
Authors: Liu Guodong , Li Xiucuo , Zhang Liucheng , Qu Xiongwei , Liu Pange , Yang Liting , Gao Jungang
Published: August 2002

Free‐radical–initiated copolymerization of N‐phenylmaleimide (NPMI) with styrene (St) at 110°C in a toluene solution initiated by AIBN was carried out by a semibatch method. The compositions of the copolymers were determined by using an elemental analyzer. The glass‐transition temperatures of the copolymers were measured by differential scanning calorimetry. All the semibatch copolymers show a single glass‐transition temperature that increases markedly with increasing NPMI content in the copolymers. The thermal stabilities of the copolymers were studied by using a programmed thermogravimetric analysis technique. Copolymers show a considerable increase in thermal stability and different degradation reaction mechanisms with increasing content of NPMI. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 417–422, 2002
Crosslinked PVC polymerization: Study on process dependencies
Authors: Han Sang Phil , Park Kyung Jun , Lee Kyungwoo
Published: August 2002

A systematic study of how different processes and crosslinking agents affect the crosslinked polymerization of poly(vinyl chloride) (PVC) to be used for plastisol application was carried out. Two processes, microsuspension (MS) and seeded polymerization (SP), and two crosslinking agents, diallyl phthalate (DAP) and 1,3‐butanediol dimethacrylate (BDMA), were considered. Variations in degree of polymerization and gel content as functions of conversion, as well as the amount of crosslinking agent, was experimentally investigated for both processes and the results were precisely analyzed. We found that the microsuspension process is much better for crosslinked polymerization of PVC to be used for plastisol application; the seeded polymerization process was restricted by the transfer of crosslinking agents to the polymerization sites. Diallyl phthalate was proven to be a good crosslinking agent as generally known until now. Consequently, to perform crosslinked PVC polymerization in industry, the type of process should be taken into account and proper materials and steps should be set up. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1947–1954, 2002
Membrane formation with presence of Lewis acid–base complexes in polymer solution
Authors: Pereira Cristina C. , Nobrega Ronaldo , Borges Cristiano P.
Published: August 2002

This work investigated membrane formation using Lewis acid–base complexes in a polymer solution, which consisted of poly(ether sulfone) (PES), Lewis acid–base complexes formed by N‐methyl‐2‐pyrrolidone (NMP, Lewis base), and dicarboxylic or monocarboxylic acids from a homologous series (Lewis acids). The solutions were characterized by viscosity measurements, IR spectroscopy, cloud point determination, and light transmission experiments. The membranes were characterized by scanning electron microscopy and gas permeation tests. The results indicated that the solvent–additive interaction, which is a function of their capacity to form complexes, and the acid chain length directly affect the viscosity and miscibility region. Consequently, these parameters combined with the complex dissociation influence the precipitation velocity of the polymer solutions, which will then affect the membrane transport properties. It is also pointed out that the membranes prepared by using 25 wt % PES at the same acid/NMP molar ratios and with different acids presented permeability coefficients in agreement with the binodal shift obtained in pseudoternary phase diagrams. Furthermore, when these solutions were exposed to the environment for a long period of time, the demixing onset sequence also agreed with the miscibility region for all solutions, except for the adipic acid solution because of its extremely high viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2022–2034, 2002
Preparation of chitosan‐bound nitrobenzaldehyde metal complexes and studies on its catalytic oxidative activity and reactive mechanism
Authors: Chang Yue , Wang Yunpu , Su Zhixing
Published: August 2002

Chitosan‐bound nitrobenzaldehyde metal complexes (m‐CNBDM and o‐CNBDM, where M is Mn or Ni) were prepared and characterized by infrared, X‐ray photoelectron spectroscopy, solid‐state 13C‐NMR cross‐polarity/magic‐angle spinning, inductively coupled plasma, and elemental analysis. The complexes were found to be catalysts for the oxidation of hydrocarbons with molecular oxygen under mild conditions. o‐CNBDNi has a certain catalytic activity in the oxidation of n‐propylbenzene and isopropylbenzene and has no activity in the oxidation of ethylbenzene. Both o‐CNBDMn and m‐CNBDNi catalyze the oxidation of all the aforementioned hydrocarbons, whereas m‐CNBDMn has no catalytic activity. The main oxidative products of ethylbenzene and n‐propylbenzene are the same as α‐ol and α‐one, but they are 2‐benzyl‐isopropynol and isopropylbenzene peroxide for isopropylbenzene. A mechanism for the catalytic oxidative process is proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2188–2194, 2002
Acetal‐induced strength increases and lower resin content of MUF and other polycondensation adhesives
Authors: Pizzi A. , Beaujean M. , Zhao C. , Properzi M. , Huang Z.
Published: August 2002

Acetals such as methylal and ethylal are shown to be particularly effective additives in improving the strength of wood boards bonded with melamine‐ urea‐formaldehyde (MUF) resins, although they show some appreciable but lesser effect on other resins too, particularly phenol‐ formaldehyde resins. They equally allow a considerable decrease in resin loading, and thus, in melamine content, on the bonded wood panel and at parity of performance. Their development as additives is then primarily, but not only, targeted at the MUF adhesive resins. One‐third decreases in MUF adhesives loading at parity of performance or equally internal bond (IB) strength increases approximately up to 50% by addition of methylal are shown to be possible by laboratory particleboard as well as by thermomechanical analysis (TMA). The reasons for methylal and ethylal behavior were studied by a variety of techniques, including liquid‐ and solid‐ phase 13C‐NMR and could be mostly ascribed to the increased effectiveness and participation of the melamine to resin crosslinking due to its now preferentially homogeneous rather than heterogeneous reactions, consequences of the increased solubility in water afforded by the acetal cosolvents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2561–2571, 2002
Mercapto‐modified copolymers in elastomer blends. IV. The compatibilization of natural rubber/EPDM blends
Authors: Sirqueira Alex S. , Soares Bluma G.
Published: August 2002

Ethylene—propylene—diene functionalized with mercapto groups (EPDMSH) was employed as compatibilizing agent for natural rubber (NR)/EPDM blends, resulting in a substantial increase of the ultimate tensile strength of these blends without affecting the elongation at break. There is also a decrease of the curing time with the addition of as low as 2.5 phr of EPDMSH, mainly in NR/EPDM (70:30 wt %) blend, indicating the accelerator effect of this functionalized copolymer. This copolymer also increased the crosslink degree and the gel content. From dynamic mechanical analysis (DMTA), it was demonstrated that EPDMSH improves the covulcanization process. The reactive compatibilization of EPDMSH was demonstrated by the presence of insoluble material in nonvulcanized/compatibilized blends and by its thermogravimetric (TGA) analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2892–2900, 2002; DOI 10.1002/app.10283
High solids content emulsions. III. Synthesis of concentrated latices by classic emulsion polymerization
Authors: Schneider M. , Graillat C. , Guyot A. , McKenna T. F.
Published: August 2002

Two different methods of producing bi‐ and trimodal latices of a mixture of methyl methacrylate, butyl acrylate, and small amounts of acrylic acid were tested. It is shown that a combination of concentrating blends of seed particles by semibatch reaction, followed by a nucleation of small particles plus a second semibatch phase allowed us to obtain stable latices with solids contents over 65% and viscosities of below 2500 mPa s−1 with little coagulum formation. The key parameter in determining latex stability, coagulum formation, and viscosity appears to be the the particle size distribution, and especially its modification attributed to secondary nucleation. Because it is not possible to eliminate water‐soluble monomers from the polymerization recipe, secondary (homogeneous) nucleation must be minimized by careful addition of the free‐radical initiator and choice of monomer feed flow rates. The nucleation of the third population in the trimodal latices is best accomplished with a mixed surfactant system because renucleation by anionic surfactant alone leads to detrimental changes in the particle size distribution (PSD) resulting from excessive flocculation of particles. In addition, it was found that the viscosity of the final products was not sensitive to small changes in the ionic strength of the latex, although neutralization to a pH of 6 effectively doubles the final latex viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1916–1934, 2002; DOI 10.1002/app.10513
Viscoelastic behavior of AN‐g‐casein copolymer concentrated solution of sodium thiocyanate
Authors: Dong Qingzhi , Gu Lixia
Published: August 2002

The viscoelastic behavior of sodium thiocyanate concentrated solution of graft copolymer of acrylonitrile onto casein (AN‐g‐casein) was investigated in detail by nitrogen pressure capillary rheometer. The experimental results show that the concentrated solution of AN‐g‐casein is a non‐Newtonian fluid of shear thinning. The end correction increases with the increase of shear rate. In the course of practical spinning, the real shear stress only attributes about 35% to the apparent shear stress, which confirms the essentiality of end correction for the capillary extrusion of the concentrated solution of the graft copolymer. By using the Dewitt model, the Couette correction ξ and recoverable shear strain SR were analyzed and separated. Quantitative function relation of ξ and SR versus shear rate and temperature were deduced. It is a common equation within the range of experiment. In practical spinning process, the real viscoelastic parameters can be easily predicted by only a piece of flowing curve based on the common equation. Real elastic model G under any shear rate in the range of experiment was calculated. It was found that G increases with an increase of shear rate, which is opposite to the conclusion reported by Hayahara. The main reason for the error may be that Hayahara used the same Couette correction at a higher shear rate. Further, the die swell in the spinning process can be estimated efficiently. The theoretical base for the stability of AN‐g‐casein spinning technology was provided. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1721–1728, 2002; DOI 10.1002/app.10554
Reactive reinforcement of the interface of poly(ether sulfone)/poly(phenylene sulfide) polymer blend by PMR–POI
Authors: Lai Mingfang , Yang Yuming , Liu Jingjiang
Published: August 2002

The effect of polymerization of monomer reactant–polyimide (POI) as the interfacial agent on the interface characteristics, morphology features, and crystallization of poly(ether sulfone)/poly(phenylene sulfide) (PES/PPS) blends were investigated using a scanning electron microscope, FTIR, WAXD, and XPS surface analysis. It was found that the interfacial adhesion was enhanced, the particle size of the dispersed phase was reduced, and the miscibility between PES and PPS was improved by the addition of POI. It was also found that POI was an effective nucleation agent of the crystallization for PPS. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1297–1306, 2002
Preparation and properties of branched polybutylenesuccinate
Authors: Kim Eun Kyoung , Bae Jong Seok , Im Seung Soon , Kim Byoung Chul , Han Yang Kyoo
Published: August 2002

To obtain long branched polybutylene succinate (PBS), modified PBSs were prepared by introducing a branching agent, trimethylol propane (TMP), to the polycondensation system of succinic acid and 1,4‐butanediol. Molecular parameters such as absolute molecular weight and root‐mean‐square (RMS) radius of the modified PBSs were measured by gel permeation chromatography (GPC) with a multiangle laser light‐scattering (MALLS) detector. The RMS radius of TMP05, PBS prepared by incorporating 0.5 wt % TMP during polycondensation, was the smallest of all PBSs tested at the same molecular weight. The notable shear thinning and much reduced loss tangent for TMP05 qualitatively supported the difference in their molecular structures predicted by GPC. The analytical results indicated that introducing 0.5 wt % TMP produced PBS with chain branches long enough to produce molecular entanglements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1388–1394, 2001
Ammonium perchlorate–binding poly(allylamine hydrochloride) hydrogels for wastewater remediation
Authors: Kioussis Dimitri R. , Smith Daniel F. , Kofinas Peter
Published: August 2002

Systems that are capable of removing highly toxic anions from wastewater effluents, even at extremely low concentrations, are a major need in the defense industry. This study reports on the features of two new batch and continuous‐flow sorption processes with regard to ultimate removal and recovery of the perchlorate (ClO) anion from ammonium perchlorate (NH4ClO4) wastewater. The sorbent developed is a crosslinked poly(allylamine hydrochloride) (PAA·HCl) polymeric hydrogel. The pH‐sensitive PAA·HCl hydrogels were synthesized by chemically crosslinking a solution of linear PAA·HCl chains with epichlorohydrin (EPI). The perchlorate‐binding capacity of the polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium perchlorate loadings of 5770 ± 870 mg ClO/g gel were calculated from measurement of the decrease in perchlorate concentration in aqueous standard solutions using UV‐Vis spectrophotometry. Batch experiments in wastewater originating from the Naval Surface Warfare Center (NSWC) Indian Head Division showed that perchlorate concentrations decreased by 85%. Preliminary lab‐scale packed‐column experiments in wastewater achieved up to 40% reduction in total perchlorate content. The regeneration ability of the gels was demonstrated by release of the bound perchlorate anions, upon washing with a 1N NaOH solution, providing opportunities to recover and reuse the hydrogel over multiple regeneration cycles. The PAA·HCl hydrogels are demonstrated to be appropriate materials for treating wastewaters that contain ammonium perchlorate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2073–2083, 2001
Porous biodegradable polyesters. II. Physical properties, morphology, and enzymatic and alkaline hydrolysis of porous poly(ϵ‐caprolactone) films
Authors: Tsuji Hideto , Ishizaka Takeharu
Published: August 2002

Porous poly(ϵ‐caprolactone) (PCL) films were prepared by water extraction of poly(ethylene oxide) (PEO) from their solution‐cast phase‐separated blend films and the dependence of their blend ratio [XPCL = PCL/(PEO + PCL)] and molecular weight of PEO on the porosity, pore size, crystallinity, crystalline thickness, mechanical properties, morphology, and enzymatic and alkaline hydrolysis of the porous PCL films were investigated. The film porosity or extracted weight ratio was in good agreement with the expected values, irrespective of XPCL and molecular weight of PEO. The maximum pore size was larger for the porous films prepared using PEO having a lower molecular weight, compared with films prepared using PEO having a higher molecular weight at the same XPCL. Differential scanning calorimetry of the porous PCL films revealed that their crystallinity and crystalline thickness were almost constant, regardless of XPCL and molecular weight of PEO. The Young's modulus and tensile strength of the porous films decreased, whereas the elongation‐at‐break increased with decreasing XPCL. The enzymatic and alkaline hydrolysis rates of the porous films increased with a decrease in XPCL and an increase in the molecular weight of PEO. The porous PCL films having Young's modulus in the range of 2–24 kg/mm2 and enzymatic hydrolysis rate in the range of one‐ to 20‐fold that of the nonporous PCL film could be prepared by altering XPCL and the molecular weight of PEO. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2281–2291, 2001
Palladium sorption on glutaraldehyde‐crosslinked chitosan in fixed‐bed systems
Authors: Ruiz Montserrat , Sastre Ana Maria , Zikan Maria Celia , Guibal Eric
Published: August 2002

Palladium sorption on glutaraldehyde‐crosslinked chitosan was studied in fixed‐bed column systems. Sorption performances were controlled mainly by the presence of competitor anions in the solution: The presence of sulfate, chloride, or nitrate (to a lesser extent) significantly decrease sorption properties. Although the influence of other operating conditions such as particle size, column depth, and flow velocity on sorption breakthrough cannot be completely neglected, palladium sorption is less significantly controlled by these parameters than for the sorption of other metal ions, owing to fast mass transfer and weak intraparticle diffusion control. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 153–165, 2001
Mechanical properties and ionic conductivity of gel polymer electrolyte based on poly(vinylidene‐fluoride‐co‐hexafluoropropylene)
Authors: Kim Seong Hun , Choi Jong Kuk , Bae Young Chan
Published: August 2002

Gel polymer electrolytes were prepared from poly(vinylidene‐fluoride‐co‐hexafluoropropylene) (PVH), which had higher mechanical properties and a higher dielectric constant (ϵ = 8–13) than other polymeric matrixes. The mechanical properties and ionic conductivities were investigated as a function of the blend ratio of the electrolyte solution and polymer matrix. Ethylene carbonate/γ‐butyrolactone and lithium triflate were used as the solvent and salt, respectively. The mechanical properties such as the tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09 × 10−3 S/cm at 25°C for 40 wt % PVH against the electrolyte solution. The tensile strength, tensile modulus, and compression modulus were increased with increasing PVH content and they all abruptly changed between 70 and 80 wt % PVH. The dynamic shear moduli showed behavior typical of a gel and varied with the shear strain amplitude or applied frequencies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 948–956, 2001
Microstructural changes of phenolic resin during pyrolysis
Authors: Ko Tse‐Hao , Kuo Wen‐Shyong , Chang Ying‐Huang
Published: August 2002

After curing, phenol‐formaldehyde resins were postcured at 230°C in air for 32 h and then carbonized and graphitized from 300 to 2400°C. Thermal fragmentation and condensation of the polymer structure occurred above 300°C. The crystal size of the cured phenolic resins decreased with the temperature increase. Above 600°C the original resin structures disappeared completely. Below 1000°C the stack size (Lc) and crystal size (La) were small. Above 1000°C the Lc increased with the increasing treatment temperature. The carbonized and graphitized resins were characterized using Raman spectroscopy. Below 400°C there were no carbon structures in the Raman spectra analysis. Above 500°C the G and D bands appeared. The frequency of the G band of all carbonized and graphitized samples shifted to 1600 cm−1 from the 1582 cm−1 of graphite. The D band shifted to 1330 cm−1 from the 1357 cm−1 of the imperfect carbon. The carbonized and graphitized phenolic resins could not be considered as truly glassy or amorphous carbon materials because they had some degree of order in the basal plane. However, the crystal size was very small even at 2400°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1084–1089, 2001
Large deformation mechanical behavior of gelatin–maltodextrin composite gels
Authors: Normand Valery , Plucknett Kevin P. , Pomfret Stephen J. , Ferdinando Dudley , Norton Ian T.
Published: August 2002

The large deformation failure behavior of gelatin–maltodextrin composite gels was assessed. All the studied compositions were selected to lie within the incompatibility domain of the gelatin–maltodextrin phase diagram at 60°C, which produced gelatin continuous (maltodextrin included) and maltodextrin continuous (gelatin included) composites. Composite microstructural evaluation was performed using confocal laser scanning microscopy (CLSM). The large deformation mechanical behavior was measured in tension and compression experiments. Crack–microstructure interactions were investigated by dynamic experiments on the CLSM. The gelatin continuous composites exhibited pseudo‐yielding behavior during tension and compression testing, and there was a significant decrease in modulus that arose from interfacial debonding. Conversely, the maltodextrin continuous composites exhibited an essentially brittle failure behavior, and there was an approximately linear increase in stress with increasing strain until fracture (which occurred at significantly lower strains than for the gelatin continuous composites). The CLSM observation of the failure of the notched samples also demonstrated interfacial debonding in the crack path; however, this occurred at significantly smaller strains than for the gelatin continuous samples with minimal elastic–plastic deformation of the maltodextrin matrix. The Poisson ratio was estimated to be close to 0.5 for these composites for all examined compositions. Compositions corresponding to a tie line of the phase diagram were also investigated to assess the influence of the relative phase volume (for constant phase compositions) on the failure behavior. The majority of the parameters subsequently extracted from the stress–strain curves were apparently functions of the individual phase volumes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 124–135, 2001
Assessment of efficacy of trivalent lanthanum complex as surface modifier of calcium carbonate
Authors: Feng Jiachun , Chen Mingcai , Huang Zhitang
Published: August 2002

A complex of trivalent lanthanum stearate with stearin (REC) was used as a surface modifier to treat calcium carbonate, and its efficacy was assessed. The measurement of the viscosity of a CaCO3/liquid paraffin suspension demonstrated that REC treatment could considerably improve the dispersion of filler in nonpolar media. The FTIR spectrum analysis revealed that the REC bonded to the CaCO3 surface not only by physical absorption but also by a chemical reaction. The REC could change the surface properties of CaCO3, resulting in greater hydrophobicity of the surface and enhanced compatibility with nonpolar matrices. The mechanical properties and melt flow rate (MFR) examination of polypropylene (PP)/CaCO3 composites showed that REC treatment remarkably enhanced the toughness and MFR of composites at higher filler loading. The fractured surface observation with SEM showed improved filler dispersion and enhanced interfacial adhesion between the filler and matrix in PP composites filled with REC‐treated CaCO3. All these improvements demonstrated that REC is an effective surface modifier of CaCO3. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1339–1345, 2001
An analysis of the correlation between structural anisotropy and dimensional stability for drawn poly(lactic acid) films
Authors: Smith Patrick B. , Leugers Anne , Kang Shuhui , Hsu Shaw Ling , Yang Xiaozhen
Published: August 2002

The anisotropic structures found in drawn poly(lactic acid) films are strongly correlated to their overall dimensional stability. Several aspects of this relationship can be efficiently characterized by Raman spectroscopy. We determined the degree of orientation in these drawn films by measuring the relative intensity of the polarized and depolarized components and the shift in the relative band positions. The bandwidth and specific band frequency also correlated well with the degree of sample crystallinity. These aspects make the Raman method amenable for the online monitoring of orientation and crystallinity in commercial processes. A molecular understanding of heat setting to reduce film shrinkage is also proposed. Raman data from films that were heat‐set while physically constrained suggest that amorphous‐phase relaxation does not occur during heat setting. Rather, the level of crystallinity increases substantially, indicating that the cause of low shrinkage in the films was due to crystalline network formation rather than amorphous‐phase relaxation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2497–2505, 2001
Thermally treated low density polyethylene biodegradation by Penicillium pinophilum and Aspergillus niger
Authors: Volke‐Sepúlveda T. , Saucedo‐Castañeda G. , Gutiérrez‐Rojas M. , Manzur A. , Favela‐Torres E.
Published: August 2002

Differential scanning calorimetry (DSC), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to determine morphological, structural and surface changes (biodegradation) on thermo‐oxidized (80°C, 15 days) low‐density polyethylene (TO‐LDPE) incubated with Aspergillus niger and Penicillium pinophilum fungi, with and without ethanol as cosubstrate for 31 months. TO‐LDPE mineralization by fungi was also evaluated. Significantly morphological and structural final changes on biologically treated TO‐LDPE samples were observed. Decreases to three units on crystallinity and crystalline lamellar thickness (0.4–1.8 Å), and increases in small‐crystals content (up to 3.2%) and mean crystallite size (8.4–14 Å) were registered. An oxidation decrease (almost twice) on samples without ethanol with respect to the control was observed, while in those with ethanol it was increased (up to 2.5 times). Double bond index increased more than twice from 21 to 31 months. The higher TO‐LDPE changes and fungi‐LDPE interaction was observed in samples with ethanol, suggesting that ethanol favors the TO‐LDPE biodegradation, at least in case of P. pinophilum, probably by means of a cometabolic process. Mineralization of 0.50 % and 0.57 % for A. niger, and of 0.64 % and 0.37 % for P. pinophilum were obtained, for samples with and without ethanol, respectively. A model to explain morphological and structural changes on biologically treated TO‐LDPE is also proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 305–314, 2002
A mucoadhesive polymer prepared by template polymerization of acrylic acid in the presence of poly(ethylene glycol) macromer
Authors: Chun Myung‐Kwan , Choi Hoo‐Kyun , Kang Dong‐Wan , Kim Oh‐Joong , Cho Chong‐Su
Published: August 2002

A new mucoadhesive polymer complex was prepared by the template polymerization of acrylic acid with poly(ethylene glycol) macromer (PEGM) as a template polymer. Fourier transform infrared results showed that the poly(acrylic acid) (PAA)/PEGM mucoadhesive polymer complex was formed by hydrogen bonding between the carboxyl groups of PAA and the ether groups of PEGM. The glass‐transition temperature of the PAA/PEGM mucoadhesive polymer complexes was shifted to a lower temperature as the repeating unit ratio of PAA/PEGM in the complex decreased. The dissolution rate of the PAA/PEGM mucoadhesive polymer complex was much slower than that of the PAA/poly(ethylene glycol) (PEG) mucoadhesive polymer complex and was dependent on the pH and molecular weight of PEGM. The mucoadhesive force of the PAA/PEGM mucoadhesive polymer complexes was stronger than that of commercial Carbopol 971P NF and almost the same as that of the PAA/PEG mucoadhesive polymer complex. The PAA/PEGM interpolymer complex seemed to be a better mucoadhesive polymer matrix than the PAA/PEG interpolymer complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1904–1910, 2002
Effects of aging and moisture on the dynamic viscoelastic properties of oriental lacquer (urushi) film
Authors: Obataya Eiichi , Furuta Yuhzo , Ohno Yoshitaka , Norimoto Misato , Tomita Bunichiro
Published: August 2002

The effects of aging and moisture on the dynamic viscoelastic properties of three oriental lacquer films were investigated. With aging over 1000 days at room temperature, the glass‐transition temperature of the lacquer films (Tα) shifted to higher temperatures, the maximum loss tangent (tanδα) decreased, and the storage modulus at 20°C (E) increased. These changes were analogous irrespective of lacquers. With increasing moisture content, E decreased and tanδ increased at room temperature. Although the equilibrium moisture content of the virgin lacquer (sap) film was higher than that of the clear lacquer film, its E and tanδ were more stable with an increase of moisture content. It was speculated that the polysaccharides aggregated in the sap film did not effectively contribute to the mechanical properties of the film, while their hygroscopicity resulted in higher moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2288–2294, 2002
Cognitive and task influences on Web searching behavior
Authors: Kim Kyung‐Sun , Allen Bryce
Published: August 2002

Users' individual differences and tasks are important factors that influence the use of information systems. Two independent investigations were conducted to study the impact of differences in users' cognition and search tasks on Web search activities and outcomes. Strong task effects were found on search activities and outcomes, whereas interactions between cognitive and task variables were found on search activities only. These results imply that the flexibility of the Web and Web search engines allows different users to complete different search tasks successfully. However, the search techniques used and the efficiency of the searches appear to depend on how well the individual searcher fits with the specific task.
Studies of the interactions between melatonin and 2 Hz, 0.3 mT PEMF on the proliferation and invasion of human breast cancer cells
Authors: Leman Eddy S. , Sisken Betty F. , Zimmer Stephen , Anderson Kimberly W.
Published: August 2002

Interactions between the hormone melatonin at pharmacological concentrations (10−3 M) and 2 Hz, 0.3 mT pulsed electromagnetic fields (PEMF) on the proliferation and invasion of human breast cancer cells were studied in vitro. Three types of human breast cancer cells were used in this study: MDA‐MB‐435, MDA‐MB‐231, and MCF‐7. Results showed that cellular growth of MDA‐MB‐231 cells, which were reported to be lowly metastatic, and MCF‐7 cells, which were reported to be nonmetastatic, were both significantly reduced by melatonin regardless of the presence of the field. Results also showed that MDA‐MB‐435 and MDA‐MB‐231 cells were invasive, with MDA‐MB‐231 cells being more invasive than the MDA‐MB‐435 cells for both unexposed and experimental‐PEMF groups. In addition, invasion studies showed that MCF‐7 cells were not invasive and that melatonin did not have any effects on the invasion of these cells, with or without the PEMF. It is also suggested that since metastasis requires growth and invasion into tissue, anti‐invasion agents can be used in conjunction with melatonin to prevent formation of secondary metastases. The overall studies suggest that PEMF at 2 Hz, 0.3 mT does not influence cancer metastasis; while having clinical merit in the healing of soft tissue injury, this field has shown no influence on cancer cells as 60 Hz power line fields have. Bioelectromagnetics 22:178–184, 2001. © 2001 Wiley‐Liss, Inc.
Dielectric response of some biological tissues
Authors: El‐Lakkani Ali
Published: August 2002

The dielectric properties of two freshly excised mice tissue samples (kidney, skeletal muscle) and also freshly excised Ehrlich solid tumor were measured in the frequency range from 20 Hz to 100 kHz using RLC bridges. The data were fitted to a summation of multiple Cole–Cole dispersion and also to the constant power law which is related formally to the fractal geometries of tissues using a genetic algorithm for optimization developed by the author. The data were in good agreement with the Cole–Cole equation for the three samples. Bioelectromagnetics 22:272–279, 2001. © 2001 Wiley‐Liss, Inc.
Basis for optimization of in vitro exposure apparatus for health hazard evaluations of mobile communications
Authors: Schönborn Frank , Poković Katja , Burkhardt Michael , Kuster Niels
Published: August 2002

The main objective of this paper is to carefully study the fields induced in flasks exposed to RF electromagnetic fields. The study focuses on the widely used 60 mm Petri dishes and rectangular T‐75 flasks for the two following cases: 1) cells in homogeneous suspension and 2) cell monolayers. The dependence of the coupling and the homogeneity of the SAR distribution on frequency (0.7 GHz to 2.5 GHz), polarization (E, H and k polarizations) and the amount of medium (1.9 mm to 4.7 mm medium height) is studied. In addition, the effects of the environment, meniscus and field impedance as well as the distortion of the incident field are discussed. Based on these results, advantages and disadvantages of different fundamental designs of apparatus used in the past are compared. These are TEM cells, HF chambers, radial transmission lines (RTL), waveguides and wire patch cells. Furthermore, the major optimization parameters are identified for the development of highly optimized exposure systems, enabling the conduct of high quality experiments. Bioelectromagnetics 22:547–559, 2001. © 2001 Wiley‐Liss, Inc.
Raman spectroscopy study of acid–base and structural properties of 9‐[2‐(phosphonomethoxy)ethyl]adenine in aqueous solutions
Authors: Kopecký Vladimír , Mojzeš Peter , Burda Jaroslav V. , Dostál Lubomír
Published: August 2002

The acid–base properties of the acyclic antiviral nucleotide analogue 9‐ [2‐(phosphonomethoxy)ethyl] adenine (PMEA) in aqueous solutions are studied by means of Raman spectroscopy in a pH range of 1–11 and compared with the properties of its common adenosine monophosphate counterparts (5′‐AMP, 3′‐AMP, and 2′‐AMP). Factor analysis is used to separate the spectra of pure ionic species (PMEA2−, HPMEA−, H2PMEA, H3PMEA+) in order to determine their abundance, sites of protonation, and corresponding spectroscopic pKa values. The characteristic Raman features of the neutral adenine moiety in PMEA2− and HPMEA− species resemble those of neutral adenine in the AMPs, whereas significant differences are observed between the Raman spectra of the N1‐protonated adenine of the solute zwitterionic H2PMEA and its N1‐protonated AMP counterparts. On the contrary, the spectrum of crystalline H2PMEA, adopting an “anti‐like” conformation, is found to be similar to the N1‐protonated AMPs in solution. To explain peculiar Raman features a “syn‐like” conformation is suggested for N1‐protonated PMEA species in aqueous solutions instead of an anti‐like one adopted by H2PMEA in crystals or by common AMPs in aqueous solutions. A physical mechanism of the anti‐like to syn‐like conformational transition of the solute PMEA that is due to adenine protonation and the flexibility of the (phosphonomethoxy)ethyl group is proposed and discussed. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 285–288, 2002
FTIR study of five complex β‐lactam molecules
Authors: Gil Manuel , Núñez José Luís , Palafox Mauricio Alcolea , Iza Nerea
Published: August 2002

Five monocyclic 4‐benzoyl‐4‐phenyl‐β‐lactam derivatives in carbon tetrachloride solutions were studied by FTIR spectroscopy. The Fourier self‐deconvolution method was applied to enhance the resolution of the FTIR spectra. The calculated spectra of these five compounds, which were obtained by quantum mechanical methods, were compared with FTIR data. A complete assignment of the vibrational frequencies in the 4000–400 cm−1 range was made. Several vibrations were selected as being useful to characterize the β‐lactam ring. Substituents on N1 (p‐methoxyphenyl) and C3 (methyl, phenyl, maleimidyl, and phthalimidyl) on the β‐lactam ring increase the amide resonance and the planarity of the ring. The optimized geometry along with the total electric charges on the four atoms of the ring support an antibiotic action mechanism by a nucleophilic attack of the enzymes on the carbonyl carbon atom of the β‐lactam ring. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 278–294, 2001