bluuebunny/crossref_metadata_2025 huggingface dataset:
Occupational asthma in the city of São Paulo, 1995–2000, with special reference to gender analysis
Authors: Mendonça Elizabete Medina Coeli , Algranti Eduardo , Freitas Jefferson Benedito Pires de , Rosa Edna Aparecida , Freire José Antônio dos Santos , Santos Ubiratan de Paula , Pinto Jarina , Bussacos Marco Antônio
Published: May 2003

Background

Occupational asthma (OA) is the leading occupational respiratory disease in the area of São Paulo Municipality. Understanding its characteristics can provide useful information for better interventions.

Methods

From a joint registry of OA from five outpatient public clinics for occupational respiratory diseases, data on occupation, with job titles corrected by an expert evaluation, agents, exposure and symptom duration, and spirometry were analyzed by gender. Data on employment for São Paulo Municipality were used to calculate expected ratios for men/women in broad economical sectors.

Results

Three hundred and ninety four OA cases were reported with a ratio of men/women of 1.5. Women had significantly shorter exposure duration (5.6 ± 5.2 vs. 8.9 ± 9.0 years, P = 0.0005), shorter symptoms duration (2.6 ± 3.7 vs. 3.2 ± 3.5 years, P = 0.1270), and higher prevalence of previous atopy (27.0 vs. 18.4%, P = 0.0485). The main occupations related to OA cases were cleaning activities, working in plastics manufacture and in chemical and pharmaceutical plants. Women reported significantly more exposures to cleaning products, biologic agents, and textile fibers, whereas men reported more exposures to isocyanates, metal dusts and fumes, oil mists, wood dusts and anhydrides. Women presented an increased risk of OA in the service sector (odds ratio (OR) = 1.77, confidence interval (CI) = 1.61–1.96).

Conclusions

Cleaning services was the main reported occupation and cleaning products the main reported agents. Women had significantly shorter exposure duration possibly due to difference in exposures, previous atopy, and behavior. There was an excess of cases of women in the service sector. Am. J. Ind. Med. 43:611–617, 2003. © 2003 Wiley‐Liss, Inc.
Environmental risk factors and work‐related lower respiratory symptoms in 80 office buildings: An exploratory analysis of NIOSH data
Authors: Mendell Mark J. , Naco Gina M. , Wilcox Thomas G. , Sieber W. Karl
Published: May 2003

Background

We evaluated relationships between lower respiratory symptoms and risk factors for microbiological contamination in office buildings.

Methods

The National Institute for Occupational Safety and Health collected data from 80 office buildings during standardized indoor environmental health hazard evaluations. Present analyses included lower respiratory symptom‐based outcome definitions and risk factors for potential microbiologic contamination. Multivariate logistic regression models for selected outcomes identified key risk factors.

Results

Adjusted odds ratios (95% confidence intervals) for “at least three of four work‐related lower respiratory symptoms” were, for debris in ventilation air intake, 2.0 (1.0–3.9), and for poor drainage in air‐conditioning drip pans, 2.6 (1.3–5.2). Adjusted associations with risk factors were consistently stronger for outcomes requiring both multiple symptoms and improvement away from work, and somewhat stronger among diagnosed asthmatics.

Conclusions

Moisture and debris in ventilation systems, possibly by supporting microbiologic growth, may increase adverse respiratory effects, particularly among asthmatics. Data from more representative buildings are needed to confirm these findings. Am. J. Ind. Med. 43:630–641, 2003. Published 2003 Wiley‐Liss, Inc.
Organic dust exposure and work‐related effects among recycling workers
Authors: Gladding Toni , Thorn Jörgen , Stott David
Published: May 2003

Objective

Organic dust exposure and work‐related symptoms and effects among household waste recycling workers in Materials Recovery Facilities (MRFs) are a concern. MRFs are a central operation where source‐segregated, dry, recyclable materials (paper, plastics, cans, etc.) are sorted, mechanically or manually, to market specifications for processing into secondary materials.

Methods

One hundred and fifty‐nine MRF workers (91%) from nine MRFs participated. Measurements of airborne total dust, endotoxin, (1→3)‐β‐D‐glucan, and a questionnaire survey were carried out. Blood data was restricted to MRFs 3, 6, and 9 (45 workers). Blood sampling investigated differential cell counts, erythrocyte sedimentation rate (ESR), and immunoglobulin (Ig)E.

Results

Workers exposed to higher amounts of endotoxin and (1→3)‐β‐D‐glucan had an increased risk for respiratory symptoms as compared to those with lower exposure. Stomach problems was associated to higher (1→3)‐β‐D‐glucan exposure. MRF 3 had a higher (1→3)‐β‐d‐glucan exposure compared to 6 and 9, and respiratory symptoms, unusual tiredness, and vomiting were reported more often in MRF 3. Monocyte numbers and ESR were significantly decreased in MRF 3 compared to MRF 6 and 9, but all measured values were within normal ranges.

Conclusions

The results suggest that MRF workers exposed to higher levels of endotoxin and (1→3)‐β‐D‐glucan at their work sites exhibit various work‐related symptoms, and that the longer a worker is in the MRF environment, the more likely he is to become affected by various respiratory and gastrointestinal symptoms. Am. J. Ind. Med. 43:584–591, 2003. © 2003 Wiley‐Liss, Inc.
Cohort mortality study of employees at the Celanese plant in Pampa, Texas
Authors: Mandel Jack S. , Chapman Pamela , Amsel Jon
Published: May 2003

Background

The mortality experience of chemical workers from the Pampa, Texas Celanese Ltd. plant through 1991 has been previously reported. This study updates that effort and presents an additional seven years of data and follow‐up that provided 268 additional cohort members and 71 new deaths.

Methods

Mortality was determined through December 31, 1998, the period for which the National Death Index could provide information on deaths. The mortality experience of Celanese Ltd. employees was compared to that of the general population of the United States. All cause and cause‐specific standardized mortality ratios (SMRs) were calculated.

Results

For the entire cohort, several causes of death including all causes (SMR = 65.9; 95% confidence interval (CI) = 56.9–76.0), heart disease (SMR = 69.1; 95% CI = 53.6–87.8), and all malignant neoplasms (SMR = 74.2; 95% CI = 56.3–95.9) were significantly less than expected. SMRs were also calculated separately for white men, non‐white men, and women. Unlike the initial study, the SMR for prostate cancer among white males was not significantly elevated (SMR=176.1; 95% CI = 76.0–347.0) and was much lower than the prior SMR of 330.4. This suggests that the initial findings, which were based on a small number of deaths, were likely due to chance.

Conclusions

Overall, Celanese Ltd. employees from the Pampa plant have significantly lower than expected SMRs for several causes of death, and no causes of death that are significantly elevated. Am. J. Ind. Med. 43:656–661, 2003. © 2003 Wiley‐Liss, Inc.
Monitoring of DNA damage in foundry and pottery workers exposed to silica by the alkaline comet assay
Authors: Başaran Nurşen , Shubair Mohammed , Ündeğer Ülkü , Kars Ayşe
Published: May 2003

Background

Workers in foundry and pottery are exposed to a mixture of chemicals and silica, which is suspected to cause genetic alterations.

Methods

To investigate the potential hazard associated with the occupational exposure to silica, DNA damage in the peripheral lymphocytes of 30 foundry and 22 pottery workers were examined by the alkaline single‐cell gel electrophoresis or Comet Assay, and compared to 52 healthy subjects with no history of occupational silica or chemical exposure.

Results

The DNA damage observed in the lymphocytes of both foundry and pottery workers was significantly higher than that in their controls. Cigarette smoking was also related to DNA damage since the DNA damage observed in smoking silica‐exposed workers compared with the non‐smoking workers was significantly higher.

Conclusions

Occupational exposure of silica from foundry and pottery workplaces has been associated with the increased DNA damage and smoking which represents an additional risk factor and must be avoided. Am. J. Ind. Med. 43:602–610, 2003. © 2003 Wiley‐Liss, Inc.
Testicular cancer among Swedish pulp and paper workers
Authors: Andersson Eva , Nilsson Ralph , Torén Kjell
Published: May 2003

Background

The incidence of testicular cancer has increased in recent decades. The aims of the present study were to elucidate whether Swedish paper and pulp mill workers had an increased incidence of testicular cancer, and to investigate whether certain occupational groups within the pulp and paper mill workforce were at increased risk.

Methods

The study was based on the Swedish Cancer Environment Register, which links the incidence of cancer for the period 1971–1990 with 1960 and 1970 National Census data on specific industries and occupations for all employed subjects in Sweden.

Results

Among maintenance workers employed both in 1960 and in 1970 in paper mills there was an increased risk for testicular cancer (standardized incidence ratio (SIR) 7.4, 95% confidence intervals (CI) 1.5–22), especially for seminomas (SIR 10.1, 95% CI 2.1–29). Maintenance workers were also at increased risk when analyzing workers employed in 1960, 1970, or both years.

Conclusions

This study indicates an increased risk for testicular cancer, especially seminomas, among maintenance workers, but not among process workers, in Swedish paper mills. Am. J. Ind. Med. 43:642–646, 2003. © 2003 Wiley‐Liss, Inc.
Occupational dermatoses among Polish private farmers, 1991–1999
Authors: Spiewak Radoslaw
Published: May 2003

Background

Little is known about work‐related skin diseases among Polish self‐employed farmers. In the National Register of Occupational Diseases, private farmers are placed in one category together with other agricultural workers, despite fundamental differences in compensation legislation and separate insurance institutions. The Agricultural Social Insurance Fund reports only on numbers of compensated cases. The aim of this study was to create reliable statistics on occupational dermatoses among private farmers.

Methods

All cases of work‐related skin diseases diagnosed from 1991 to 1999 were included in the statistics. Compensation records of the Agricultural Social Insurance Fund were analyzed for diagnoses, causative factors, and health impairment of the skin.

Results

The first occupational dermatosis was registered in 1992. Until the end of 1999, there were 101 cases (63 women and 38 men). The incidence rose from 0.006/10,000/year in 1992 to 0.189/10,000/year in 1999. Allergic contact dermatitis was the most common diagnosis (86%), followed by infectious skin diseases (10%), irritant contact dermatitis (3%), and urticaria (2%). The most frequently identified causative factors were plant dusts (38%), animal allergens (36%), metals (29%), pesticides (18%), and rubber chemicals (15%). The median impairment due to skin disease was 20% (range 2–36%).

Conclusions

Since the introduction of workers' compensation, the numbers of occupational dermatoses diagnosed in Polish private farmers have increased rapidly. However, compared to countries with a longer experience in this field, these figures remain low, probably due to low detection of these diseases. Am. J. Ind. Med. 43:647–655, 2003. © 2003 Wiley‐Liss, Inc.
Be the fairest of them all: Challenges and recommendations for the treatment of gender in occupational health research
Authors: Messing Karen , Punnett Laura , Bond Meg , Alexanderson Kristina , Pyle Jean , Zahm Shelia , Wegman David , Stock Susan R. , de Grosbois Sylvie
Published: May 2003

Background

Both women's and men's occupational health problems merit scientific attention. Researchers need to consider the effect of gender on how occupational health issues are experienced, expressed, defined, and addressed. More serious consideration of gender‐related factors will help identify risk factors for both women and men.

Methods

The authors, who come from a number of disciplines (ergonomics, epidemiology, public health, social medicine, community psychology, economics, sociology) pooled their critiques in order to arrive at the most common and significant problems faced by occupational health researchers who wish to consider gender appropriately.

Results

This paper describes some ways that gender can be and has been handled in studies of occupational health, as well as some of the consequences. The paper also suggests specific research practices that avoid errors. Obstacles to gender‐sensitive practices are considered.

Conclusions

Although gender‐sensitive practices may be difficult to operationalize in some cases, they enrich the scientific quality of research and should lead to better data and ultimately to well‐targeted prevention programs. Am. J. Ind. Med. 43:618–629, 2003. © 2003 Wiley‐Liss, Inc.
Surveillance of respiratory diseases among construction and trade workers at Department of Energy nuclear sites
Authors: Dement John M. , Welch Laura , Bingham Eula , Cameron Buck , Rice Carol , Quinn Patricia , Ringen Knut
Published: May 2003

Background

Medical screening programs were begun in 1996 and 1997 at three Department of Energy (DOE) nuclear weapons facilities (Hanford Nuclear Reservation, Oak Ridge, and the Savannah River Site) to evaluate whether current and former construction workers are at significant risk for occupational illnesses. The focus of this report is pneumoconiosis associated with exposures to asbestos and silica among workers enrolled in the screening programs through September 30, 2001.

Methods

Workers provided a detailed work and exposure history and underwent a respiratory examination, which included a respiratory history and symptom questionnaire, a posterior–anterior (P–A) chest radiograph, and spirometry. Both stratified and multivariate logistic regression analyses were used to explore the risk of disease by duration of DOE employment and frequency of exposure, while controlling for potential confounders such as age, race, sex, and other work in the construction and building trades.

Results

Of the 2,602 workers, 25.2% showed one or more chest X‐ray changes by ILO criteria and 42.7% demonstrated one or more pulmonary function defects. The overall prevalence of parenchymal changes by ILO criteria (profusion 1/0 or greater) was 5.4%. In the logistic regression models, the odds ratio for parenchymal disease was 2.6 (95% confidence interval (CI) = 1.0–6.6) for workers employed 6 to 20 years at Hanford or Savannah River and increased to 3.6 (95% CI = 1.1–11.6) for workers employed more than 35 years, with additional incremental risks for workers reporting routine exposures to asbestos or silica.

Conclusions

Continued surveillance of workers is important given their increased risk of disease progression and their risk for asbestos related malignancies. Smoking cessation programs should also be high priority and continued abstinence for former smokers reinforced. Although the observed respiratory disease patterns are largely reflective of past exposures, these findings suggest that DOE needs to continue to review industrial hygiene control programs for work tasks involving maintenance, repair, renovation, and demolition. Am. J. Ind. Med. 43:559–573, 2003. © 2003 Wiley‐Liss, Inc.
Beryllium‐stimulated neopterin as a diagnostic adjunct in chronic beryllium disease
Authors: Maier Lisa A. , Kittle Lori A. , Mroz Margaret M. , Newman Lee S.
Published: May 2003

Background

The diagnosis of chronic beryllium disease (CBD) relies on the beryllium lymphocyte proliferation test (BeLPT) to demonstrate a Be specific immune response. This test has improved early diagnosis, but cannot discriminate beryllium sensitization (BeS) from CBD. We previously found high neopterin levels in CBD patients' serum and questioned whether Be‐stimulated neopterin production by peripheral blood cells in vitro might be useful in the diagnosis of CBD.

Methods

CBD, BeS, Be exposed workers without disease (Be‐exp) normal controls and sarcoidosis subjects were enrolled. Peripheral blood mononuclear cells (PBMN) were cultured in the presence and absence of beryllium sulfate. Neopterin levels were determined from cell supernatants by enzyme linked immunosorbent assay (ELISA). Clinical evaluation of CBD subjects included chest radiography, pulmonary function testing, exercise testing, and the BeLPT.

Results

CBD patients produced higher levels of neopterin in both unstimulated and Be‐stimulated conditions compared to all other subjects (P < 0.0001). Unstimulated neopterin mononuclear cell levels overlapped among groups, however, Be‐stimulated neopterin levels in CBD showed little overlap. Using a neopterin concentration of 2.5 ng/ml as a cutoff, Be‐stimulated neopterin had a sensitivity of 80% and specificity of 100% for CBD and was able to differentiate CBD from BeS. Be‐stimulated neopterin was inversely related to measures of pulmonary function, exercise capacity, and gas exchange.

Conclusions

Neopterin may be a useful diagnostic adjunct in the non‐invasive assessment of CBD, differentiating CBD from BeS. Further studies will be required to determine how it performs in workplace screening. Am. J. Ind. Med. 43:592–601, 2003. © 2003 Wiley‐Liss, Inc.
Lung function decrease in relation to pneumoconiosis and exposure to quartz‐containing dust in construction workers
Authors: Tjoe‐Nij Evelyn , Meer Gea de , Smit Jet , Heederik Dick
Published: May 2003

Background

Prevalence of exposure related respiratory symptoms and decreases in lung function are unknown among quartz dust exposed construction workers.

Methods

In a cross‐sectional study (n = 1,335), the occurrence of respiratory symptoms, was recorded and spirometric lung function was measured. Results were associated with exposure data and presence of radiographic abnormalities and compared with a reference population.

Results

Pneumoconiosis (profusion category 1/1 or greater) was associated with increased risks of FEV1 and FVC values in the lowest 5% group, and with group‐based decreases of 270 ml/s and 180 ml, respectively. Average lung function of construction workers was somewhat lower compared to a Dutch reference population. Lung function was not associated with exposure, except for a reduction in FVC of 5 ml per year for those with higher exposure.

Conclusions

In quartz dust exposed construction workers obstructive and restrictive lung function loss was detected. Am. J. Ind. Med. 43:574–583, 2003. © 2003 Wiley‐Liss, Inc.
Four‐year study of controlled timed breeding of rhesus monkeys (Macaca mulatta)
Authors: Phillippi‐Falkenstein Kathrine , Harrison Richard M.
Published: May 2003

As part of the timed breeding colony at Tulane National Primate Research Center, exogenous progesterone administration (5 mg/day for 10 days) has been used to select conception dates by inducing artificial luteal phases in female rhesus monkeys. A retrospective analysis of data obtained during four breeding seasons (1998–2001) revealed that conceptions occurred an average of 18 days after the last administration of progesterone. The age of the female to be bred, previous pregnancy history, and timing of breeding during the breeding season were determined to be critical factors in the success of the procedure. The benefit of this method of timed breeding is that it does not require tracking of menstrual cycles, which can be labor‐intensive and requires that animals be monitored several months in advance of breeding to determine each female's individual cycle length. It also provided an efficient use of breeding‐age males. Am. J. Primatol. 60:23–28, 2003. © 2003 Wiley‐Liss, Inc.
Stereotypic and self‐injurious behavior in rhesus macaques: A survey and retrospective analysis of environment and early experience
Authors: Lutz Corrine , Well Arnold , Novak Melinda
Published: May 2003

Abnormal behavior in captive rhesus monkeys can range from active whole‐body and self‐directed stereotypies to self‐injurious behavior (SIB). Although abnormal behaviors are common in singly‐housed rhesus monkeys, the type and frequency of these behaviors are highly variable across individual animals, and the factors influencing them are equally varied. The purpose of this investigation was to survey abnormal behavior in a large population of rhesus macaques, to characterize the relationship between stereotypies and self‐injury, and to identify potential risk factors for these aberrant behaviors. Behavioral assessments of 362 individually housed rhesus monkeys were collected at the New England Regional Primate Research Center (NERPRC) and combined with colony records. Of the 362 animals surveyed, 321 exhibited at least one abnormal behavior (mean: 2.3, range: 1–8). The most common behavior was pacing. Sex differences were apparent, with males showing more abnormal behavior than females. SIB was also associated with stereotypies. Animals with a veterinary record of self‐injury exhibited a greater number of self‐directed stereotypies than those that did not self‐injure. Housing and protocol conditions, such as individual housing at an early age, longer time housed individually, greater number of blood draws, and nursery rearing, were shown to be risk factors for abnormal behavior. Thus, many factors may influence the development and maintenance of abnormal behavior in captive primates. Some of these factors are intrinsic to the individual (e.g., sex effects), whereas others are related to colony management practices, rearing conditions, and research protocols. Am. J. Primatol. 60:1–15, 2003. © 2003 Wiley‐Liss, Inc.
Influence of estradiol on cortisol secretion in ovariectomized cynomolgus macaques (Macaca fascicularis)
Authors: Stavisky R.C. , Watson S.L. , Anthony M.S. , Manuck S.B. , Adams M.R. , Kaplan J.R.
Published: May 2003

In an investigation of cortisol secretion in fully mature, ovariectomized cynomolgus monkeys (Macaca fascicularis), we compared monkeys that were given either placebo (OVX, n = 26) or 17β estradiol (E2 ) (EST, n = 26) in a daily oral dose. Serum cortisol concentrations were measured prior to the experimental manipulation and 3, 6, 9, and 12 months following initiation of treatment. Pretreatment cortisol values did not differ between groups. Assessment of the treatment period values revealed that cortisol concentrations were significantly higher (≈10%) in the EST than in the OVX monkeys. Cortisol also varied significantly across periods of sampling. This time‐dependent variation was attributable to elevations in months 6 and 9 (when daylight was generally long), relative to months 3 and 12 (when daylight was relatively short). The modest stimulatory effect of estrogen on corticosteroid production observed in this study is consistent with what has been seen in women, and contrasts with the more robust effects observed in New World monkeys. The possible relationship between season and cortisol secretion observed here has not been previously described in monkeys. Am. J. Primatol. 60:17–22, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of biological diversity through analysis of discrete cranial traits
Authors: Hanihara Tsunehiko , Ishida Hajime , Dodo Yukio
Published: May 2003

In the present study, the frequency distributions of 20 discrete cranial traits in 70 major human populations from around the world were analyzed. The principal‐coordinate and neighbor‐joining analyses of Smith's mean measure of divergence (MMD), based on trait frequencies, indicate that 1) the clustering pattern is similar to those based on classic genetic markers, DNA polymorphisms, and craniometrics; 2) significant interregional separation and intraregional diversity are present in Subsaharan Africans; 3) clinal relationships exist among regional groups; 4) intraregional discontinuity exists in some populations inhabiting peripheral or isolated areas. For example, the Ainu are the most distinct outliers of the East Asian populations. These patterns suggest that founder effects, genetic drift, isolation, and population structure are the primary causes of regional variation in discrete cranial traits. Our results are compatible with a single origin for modern humans as well as the multiregional model, similar to the results of Relethford and Harpending ([1994] Am. J. Phys. Anthropol. 95:249–270). The results presented here provide additional measures of the morphological variation and diversification of modern human populations. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Peopling of three Mediterranean Islands (Corsica, Sardinia, and Sicily) inferred by Y‐chromosome biallelic variability
Authors: Francalacci P. , Morelli L. , Underhill P.A. , Lillie A.S. , Passarino G. , Useli A. , Madeddu R. , Paoli G. , Tofanelli S. , Calò C.M. , Ghiani M.E. , Varesi L. , Memmi M. , Vona G. , Lin A.A. , Oefner P. , Cavalli‐Sforza L.L.
Published: May 2003

An informative set of biallelic polymorphisms was used to study the structure of Y‐chromosome variability in a sample from the Mediterranean islands of Corsica and Sicily, and compared with data on Sardinia to gain insights into the ethnogenesis of these island populations. The results were interpreted in a broader Mediterranean context by including in the analysis neighboring populations previously studied with the same methodology. All samples studied were enclosed in the comparable spectrum of European Y‐chromosome variability. Pronounced differences were observed between the islands as well as in the percentages of haplotypes previously shown to have distinctive patterns of continental phylogeography. Approximately 60% of the Sicilian haplotypes are also prevalent in Southern Italy and Greece. Conversely, the Corsican sample had elevated levels of alternative haplotypes common in Northern Italy. Sardinia showed a haplotype ratio similar to that observed in Corsica, but with a remarkable difference in the presence of a lineage defined by marker M26, which approaches 35% in Sardinia but seems absent in Corsica. Although geographically adjacent, the data suggest different colonization histories and a minimal amount of recent gene flow between them. Our results identify possible ancestral continental sources of the various island populations and underscore the influence of founder effect and genetic drift. The Y‐chromosome data are consistent with comparable mtDNA data at the RFLP haplogroup level of resolution, as well as linguistic and historic knowledge. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Watching Photoinduced Chemistry and Molecular Energy Flow in Solution in Real Time
Authors: Aßmann Jens , Kling Matthias , Abel Bernd
Published: May 2003

Energized molecules are the essential actors in chemical transformations in solution. As the rearrangement of bonds requires a movement of nuclei, vibrational energy is often the driving force for a reaction. Vibrational energy can be redistributed within the “hot” molecule, or relaxation can occur when molecules interact. Both processes govern the rates, pathways, and quantum yields of chemical transformations in solution. Unfortunately, energy transfer and the breaking, formation, and rearrangement of bonds take place on ultrafast timescales. This Review highlights experimental approaches for the direct, ultrafast measurement of photoinduced femtochemistry and energy flow in solution. In the first part of this Review, we summarize recent experiments on intra‐ and intermolecular energy transfer. The second part discusses photoinduced decomposition of large organic peroxides, which are used as initiators in free radical polymerization. The mechanisms and timescales of their decarboxylation determine the initial steps of polymerization and the microstructure of the polymer product.
Cover Picture: Towards “Mechanochemistry”: Mechanically Induced Isomerizations of Thiolate–Gold Clusters (Angew. Chem. Int. Ed. 20/2003)
Authors: Krüger Daniel , Rousseau Roger , Fuchs Harald , Marx Dominik
Published: May 2003

“Mechanochemistry” is the use of mechanical forces to induce and control molecular reactions. This link between chemistry and nanophysics is illustrated by D. Marx et al. on page 2251ff. in a theoretical study: thiolate molecule is employed to stretch a gold cluster into a nanowire. The cover picture follows clockwise the isomerization steps that occur under the application of an external pulling force, such as that exerted by an atomic force microscope.
Polymerization of propylene using the high‐activity Ziegler–Natta catalyst system SiO2/MgCl2 (ethoxide type)/TiCl4/Di‐n‐butyl phthalate/triethylaluminum/dimethoxy methyl cyclohexyl silane
Authors: Zohuri G. H. , Azimfar F. , Jamjah R. , Ahmadjo S.
Published: May 2003

The bisupported Ziegler–Natta catalyst system SiO2/MgCl2 (ethoxide type)/TiCl4/di‐n‐butyl phthalate/triethylaluminum (TEA)/dimethoxy methyl cyclohexyl silane (DMMCHS) was prepared. TEA and di‐n‐butyl phthalate were used as a cocatalyst and an internal donor, respectively. DMMCHS was used as an external donor. The slurry polymerization of propylene was studied with the catalyst system in n‐heptane from 45 to 70°C. The effects of the TEA and H2 concentrations, temperature, and monomer pressure on the polymerization were investigated. The optimum productivity was obtained at [Al]/[DMMCHS]/[Ti] = 61.7:6.2:1 (mol/mol/mol). The highest activity of the catalyst was obtained at 60°C. Increasing the H2 concentration to 100 mL/L increased the productivity of the catalyst, but a further increase in H2 reduced the activity of the catalyst. Increasing the propylene pressure from 1 to 7 bar significantly increased the polymer yield. The isotacticity index (II) decreased with increasing TEA, but the H2 concentration, temperature, and monomer pressure did not have a significant effect on the II value. The viscosity‐average molecular weight decreased with increasing temperature and with the addition of H2. Three catalysts with different Mg/Si molar ratios were studied under the optimum conditions. The catalyst with a Mg/Si molar ratio of approximately 0.93 showed the highest activity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1177–1181, 2003
Preparation and characterization of the complex latex formed through complexation of two polymer latexes with chemically complementary structure
Authors: Yang Mingjiao , Dan Yi
Published: May 2003

In this study, the intermacromolecular complexation of two polymers with chemically complementary structures in the latex state and the interparticle interactions were probed. Two latexes—a polydimethylsiloxane (PDMS)/poly(vinyl acetate‐co‐butyl acrylate) system, named PA latex, and a PDMS/poly(methacrylic acid) system, named PB latex—were prepared by seeded emulsion polymerization and the complex latexes were obtained through complexation of the PA latex with the PB latex. The properties of the obtained complex latexes were investigated using surface tension and viscosity measurements. The surface structure and composition of coatings obtained from the latexes were analyzed by X‐ray photoelectron spectroscopy and scanning probe microscopy. The results confirmed that there are interactions between the

(or

groups in PA and the

groups in PB. The interactions result in unique properties of the polymer latex and lead to a formation of a new structure of the coatings. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1405–1411, 2003
Inhibition of polyketone oxidation
Authors: Kalinina I. A. , Belov G. P. , Gumargalieva K. Z. , Shlyapnikov Yu. A. , Zaikov G. E.
Published: May 2003

Oxidation of polyketones [poly(ethylene ketone) (CH2CH2CO‐)n and poly(propylene ketone) (CH2CH(CH3)CO‐)n] in the presence of antioxidant [2,2′‐methylene‐bis(4‐methyl‐6‐tert‐butylphenol)] was studied in the temperature range 120–190°C. The effectiveness of the antioxidant in polyketones is much lower than that in polyolefins. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1182–1185, 2003
Preparation and characterization of poly(methyl methacrylate)–clay nanocomposites via melt intercalation: The effect of organoclay on the structure and thermal properties
Authors: Kumar Sandeep , Jog Jyoti P. , Natarajan Upendra
Published: May 2003

Nanocomposites of poly(methyl methacrylate) (PMMA) with layered silicates were prepared by the melt mixing route. The PMMA–montmorillonite hybrids were characterized by wide‐angle X‐ray diffraction, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Except for the hybrid formed with unmodified sodium montmorillonite, where a change in distribution of clay platelet stacks was observed without polymer intercalation, the use of organically modified montmorillonites produced well‐intercalated systems. An increase in the separation of the clay layers due to polymer intercalation was observed in the range 7–14 Å. TGA thermographs indicated that the onset of decomposition increased by 15–30°C, depending on the organoclay, as compared to PMMA itself. DSC results showed the existence of a glass‐transition temperature (Tg) for all the hybrids and also showed that the Tg of the hybrids were lower (by ∼10%) compared to that of PMMA. Among the various modifiers, the ones that were relatively more polar favored a greater extent of intercalation of PMMA into the clay layers. The thermal stabilities of the nanocomposites were superior to that of PMMA and were controlled by the stability of the organoclay and its interaction with PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1186–1194, 2003
Modified polyurethane with improvement of acid dye dyeability
Authors: Wang Huei‐Hsiung , Lin Li‐En
Published: May 2003

This article concerns the modification of polyurethane using polyamide 6,6 prepolymer to improve the dyeability properties of the polyurethane copolymer with acid dye. First, the carboxyl‐terminated polyamide 6,6 prepolymer was synthesized from adipic acid and 1,6‐diaminohexane. The isocyanate‐terminated polyurethane prepolymer was also synthesized from polytetramethylene glycol and 4,4′‐diphenylmethane diisocyanate in N,N‐dimethylformamide. The polyurethane prepolymer was then extended with a mixture of 1,4‐butanediol and the polyamide 6,6 prepolymer (molar ratios of 1,4‐butanediol to prepolymer being 100%, 75%, 50%, and 25%, respectively). Finally, the poly(urethane–amide) copolymers were dyed with acid dyes. The chemical, physical, and the dyeing properties of the poly(urethane–amide) coploymers are discussed. From the experimental results, it is found that the inherent viscosity of poly(urethane–amide) coploymers is increased with the increasing amount of polyamide content. The structure is proven by infrared spectra, which exhibits the absorption peaks of urethane and amide groups as we expected. From the differential scanning calorimetry measurements, it is found that the poly(urethane–amide) coploymers have two‐phase structures and good phase separation. There are four transition temperatures (Tgs, Tgh, Tms, and Tmh), but only those copolymers in PTMG 2,000 series possess Tms. Moreover, the Tgs is found to change with the length of soft segment, and the Tgh is increased with the increasing amount of polyamide content. Also, the dyed copolymers exhibit higher Tgh than those without dyeing of dye molecule, but the Tgs is not obviously changed. For mechanical properties, it is indicated that both the modulus and the strength of the coploymers are higher than those of unmodified polyurethane, but they are lowered after being dyed with dye molecule due to further separation of intermolecular distance of the dyed polyurethanes. For dye uptake in dyeing properties, it is found to increase with increasing amount of polyamide content. For dye fastness, the dyed copolymers exhibit higher grade of water fastness than that of unmodified polyurethane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1397–1404, 2003
Copolymerization and thermal behavior of methyl methacrylate with N‐(phenyl/p‐tolyl) itaconimides
Authors: Anand Vishal , Choudhary Veena
Published: May 2003

This study describes the synthesis, characterization, and thermal behavior of copolymers of methyl methacrylate (MMA) and N‐p‐tolyl itaconimide (PTI)/N‐phenyl itaconimide (I). Homopolymerization and copolymerization of N‐(phenyl/p‐tolyl) itaconimide with MMA was carried out by use of various mole fractions of N‐aryl itaconimide in the initial feed from 0.1 to 0.5, using azobisisobutyronitrile as an initiator and tetrahydrofuran as the solvent. The copolymer composition was determined by 1H‐NMR spectroscopy using the proton resonance signals attributed to –OCH3 of MMA (δ = 3.5–3.8 ppm) and the aromatic protons (δ = 7.0–7.5 ppm) of N‐aryl itaconimide. The reactivity ratios of the monomers were found to be r1 (PTI) = 1.33 ± 0.05/r2 (MMA) = 0.24 ± 0.03 and r1 (I) = 1.465 ± 0.035/r2 (MMA) = 0.385 ± 0.005. The molecular weight of the copolymers decreased with increasing mole fraction of N‐aryl itaconimide in the copolymers. Glass‐transition temperature (Tg) and thermal stability of PMMA increased with increasing amounts of itaconimides in the polymer backbone. A significant increase in the percentage char yield at 700°C was observed on incorporation of a low mole fraction of N‐aryl itaconimides. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1195–1202, 2003
Melting behavior and crystallization kinetics of starch and poly(lactic acid) composites
Authors: Ke Tianyi , Sun Xiuzhi
Published: May 2003

Differential scanning calorimetry was used to characterize the melting behavior and isothermal crystallization kinetics of pure poly(lactic acid) (PLA) and blends of PLA with various corn starch contents at varying isothermal crystallization temperatures (90–125°C). The experimental data were evaluated using the well‐known Avrami kinetic model. The Avrami exponent, constant, half‐time of crystallization, and degree of crystallinity were obtained. Talc, a nucleating agent, was also blended with PLA at 1% by volume (v/v) as a comparison. Starch effectively increased the crystallization rate of PLA, even at a 1% content, but the effect was less than that of talc. The crystallization rate of PLA increased slightly as the starch content in the blend was increased from 1 to 40%. An additional crystallization of PLA was observed, and it affected the melting point and degree of crystallinity of PLA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1203–1210, 2003
Atomic force and scanning electron microscopic studies of effect of crosslinking system on properties of maleated ethylene–propylene–diene monomer rubber composites filled with short melamine fibers
Authors: Rajeev R. S. , Bhowmick Anil K. , De S. K. , Bandyopadhyay S.
Published: May 2003

This article reports the development of new composites based on maleated ethylene–propylene–diene monomer (EPDM) rubber and melamine fiber. The compositions are cured using three different types of curing systems: conventional covalent crosslinking based on sulfur and an accelerator, fully ionic crosslinking based on zinc oxide/zinc stearate, and mixed crosslinking involving both covalent and ionic bonds. A dry bonding system comprising resorcinol, hexamethylene tetramine, and hydrated silica, popularly known as HRH, is found to increase the mechanical properties of the composites cured using both the sulfur/accelerator and mixed crosslinking systems. However, incorporation of the dry bonding system and/or melamine fiber adversely affects the strength of the composites if the linkages are fully ionic. Among the three crosslinking systems employed, composites prepared by using the mixed crosslinking system give higher tensile strength and modulus. Aging at 150°C for 48 h causes improvement in the strength and modulus of the composites cured by using the sulfur/accelerator system, particularly at higher fiber loading. However, in the case of an ionic system, both the modulus and strength drop with aging; in the case of the mixed crosslinking system, the modulus increases, but there is a drop in strength on aging. Rheological studies of the uncured compounds show that the presence of zinc stearate in the formulations of mixed and ionic crosslinking systems results in reduced viscosity and a smoother extrudate as compared to the sulfur crosslinking system. An atomic force microscopy analysis of the roughness reveals that the fiber surface roughness is reduced because of aging for the ionic crosslinking system. This is attributable to the formation of a zinc stearate layer on the fiber surface, which also reduces the adhesion between the fiber and the matrix, thereby reducing the hysteresis after aging. However, for the sulfur and mixed crosslinking system, the roughness of the fiber surface is increased and there is a concomitant increase in hysteresis. © 2003 John Wiley Periodicals, Inc. J Appl Polym Sci 89: 1211–1229, 2003
Stability and depolymerization of poly(sebacic anhydride) under high moisture environment
Authors: Chan Cheng‐Kuang , Chu I‐Ming
Published: May 2003

Polyanhydrides are found to be useful in drug delivery systems; however, these aliphatic polyanhydrides are also unstable under humidity and temperature (greater than 0°C) for their low toxicity and surface eroding mode of drug release. In this research, poly(sebacic anhydride) was synthesized for a stability and depolymerization study in high humidity a surrounding temperature of 35°C. According to the results from gel permeation chromatography, IR spectrophotometry, and differential scanning calorimetry investigations, it was found that both self‐depolymerization and hydrolysis mechanisms existed during the depolymerization process for poly(sebacic anhydride) and they can be monitored directly. These results were further compared with previous research in a depolymerization study of polyanhydrides in a vacuum and in buffer solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1423–1429, 2003
Dose distributions of high‐energy electrons into planar and cylindrical layers of low‐density polyethylene, high‐density polyethylene, poly(vinyl chloride), and copper for industrial applications
Authors: Behjat A. , Gheysari Dj. , Mojrek A.
Published: May 2003

High‐energy electron irradiation of low‐density polyethylene, high‐density polyethylene, plasticized poly(vinyl chloride) (PPVC), and copper (Cu) of various thicknesses were studied. We measured the dose distributions versus the thicknesses of various layers of these materials. Moreover, we irradiated polyethylene–Cu–polyethylene and PPVC–Cu–PPVC sandwiches and electrical conductors with Cu cores having 1.4–4.8‐mm diameters and polymeric (polyethylene and PPVC) insulation 0.6–1.1 mm thick. The irradiation was carried out with 5 and 10 MeV of electrons. The depth–dose distributions for these materials showed that 10 MeV of electrons penetrated polyethylene (up to Rp ∼ 4.5 cm), PPVC (up to Rp ∼ 3.5 cm), and Cu (up to Rp ∼ 5 mm). For the sandwiches (planar geometry), the largest dose levels were at the surfaces of the polymeric insulation materials close to the Cu sheets. For small wires, one‐sided irradiation gave a relatively uniform dose distribution, especially with 10 MeV of electrons, and excellent uniform dose distribution was obtained by two‐sided irradiation. For wires with comparatively thick insulation, two‐sided irradiation with 5 MeV of electrons provided a relatively uniform dose distribution, and a more uniform distribution for this type of wire and cable was achieved by irradiation from four sides and with 10 MeV of electrons. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1230–1241, 2003
Analysis of the thermodynamic compatibility of poly(vinyl chloride) and nitrile rubbers from inverse gas chromatography
Authors: Huang Jan‐Chan
Published: May 2003

The solubility parameter method was applied to an analysis of the solution thermodynamic data of several solutes (probes) in polymers obtained by inverse gas chromatography. Experimental data previously reported by different authors were analyzed. The polymers used as the stationary phases were poly(vinyl chloride) (PVC), two nitrile rubbers (NBRs), and PVC/NBR blends. From the retention volumes of the probes, the Flory–Huggins interaction parameters at infinite dilution were calculated. The interaction parameters, in turn, were related to the solubility parameters of the solutes and stationary phases. With a series of probes, the solubility parameters of PVC and NBRs were determined. Differences existed between the experimental values of the size‐corrected free energies of solutions and the values calculated with solubility parameters. The differences were generally negative values. When these differences obtained from two NBR rubbers were plotted versus PVC, a correlation was found. Methods for obtaining the interaction parameters of polymer blends were examined. A modified plotting method gave a linear line and an interaction parameter between two polymers consistent with the results of the solubility parameters. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1242–1249, 2003
ZnBr2‐catalyzed chemical effects in poly(acrylonitrile‐ co‐butadiene)
Authors: Vega‐Cantú Yadira , Hauge Robert , Norman Lewis , Billups W. Edward
Published: May 2003

The excellent chemical properties and resistance to oil of poly(acrylonitrile‐co‐butadiene), or nitrile–butadiene rubber (NBR), has led to the extensive use of these elastomers as O‐ring material in the oil extraction industry. The degradation of NBR gaskets is known to occur during the well completion and oil extraction process when they are exposed to bromide fluids such as ZnBr2‐based completion fluid. Samples of NBR, polyacrylonitrile, and polybutadiene were exposed to ZnBr2‐based completion fluid and analyzed by attenuated total reflectance (ATR) and diffuse reflectance IR. These analyses showed that the ZnBr2 completion fluid promoted the hydrolysis of the nitrile group to form amides and carboxylic groups. The carbon–carbon double bonds in NBR were unaffected after short exposure to ZnBr2‐based completion fluid but were quickly hydrated in acidic bromide mixtures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1250–1257, 2003
Fluorocarbon‐containing hydrophobically modified poly(acrylic acid) gels: Gel structure and water state
Authors: Tian Qin , Zhao Xi‐An , Tang Xiao‐Zhen , Zhang Yun‐Xiang
Published: May 2003

A series of hydrophobically modified poly(acrylic acid) gels (HM‐PAA gels) were prepared by radical copolymerization of acrylic acid and a small amount of hydrophobic comonomers, 2‐(N‐ethyl perfluorooctane‐sulfonamido)ethyl methacrylate and lauryl acrylate, respectively, in tert‐butanol. The effects of hydrophobic modification on the structure and water state in hydrogels were studied by atomic force microscopy, differential scanning calorimetry, and thermogravimetric analyses. Significant differences in the enthalpy of dissociation of water per molar polymer unit were found between unmodified gel and hydrophobically modified gels (HM gels). Three states of water molecules—free water, nonfreezing water, and freezing bound water—were proven to exist in HM gels. The number of nonfreezing and freezing bound water molecules associated with a polymer unit, n0 and n1, increased with the hydrophobe content and the hydrophobicity of the hydrophobes. The roles of these water molecules are discussed in relation to hydrophobic association. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1258–1265, 2003