bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic study of oxidation of cyclohexane using complex catalyst
Authors: Kishore M. Jhansi L. , Kumar Anil 
Published: April 2007

AbstractWith an effort to use a multimetallic catalyst system for oxidation of cyclohexane using oxygen, a binuclear monometallic macrocyclic ZrZr complex was prepared and covalently bonded to modified alumina support. The complex catalyst thus prepared was found to be thermally stable and was completely characterized by CHN, SEM‐EDAX, TGA, and FTIR analysis. We carried out liquid phase oxidation of cyclohexane using molecular oxygen without any solvent, coreactant, or cocatalyst at considerably mild reaction conditions (150°C, 27 atm) with extremely high selectivity. The GC‐MS of the liquid product formed showed the total conversion of as much as 19% having cyclohexanone and cyclohexanol in the ratio of 16:1. To explain the experimental data, a possible reaction mechanism has been proposed and rate constants (assuming single phase) at different temperatures were determined using an optimal curve fitting by applying genetic algorithm. We showed that the steady state approximation cannot be assumed, and for the pressure range studied (7–35 atm), the rate constants thus determined were found to be a function of temperature only. From experiments carried out at different temperatures, we found that for every rate constant, an Arrhenious type relation could be established. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Modeling of an aerosol reactor for optimizing product properties
Authors: Bain Wasmund Eric , Saberi Shadi , Coley Kenneth S. 
Published: April 2007

AbstractImportant and unique metal powders are made industrially by a variety of vapor condensation processes in tube reactors. Often, however, the fundamental mechanisms for particle formation and growth are still not well understood. In this article, a computational fluid dynamics (CFD) model was developed to examine a tube reactor's internal flow characteristics. The model identified a massive zone of fluid recirculation in the top half of the reactor. In‐situ sampling from an experimental reactor under the same conditions revealed a large increase of aerosol particle size corresponding to the region of recirculation. A first principles mass balance model based on chemical kinetics and aerosol physics was developed for this system which showed that the average particle size grew monotonically with time in the reactor. On the basis of this firmly established link between residence time and particle size, a new reactor geometry was proposed to produce a “plug‐flow” velocity profile with a narrower particle size distribution. A CFD model was used to prototype the new configuration, and then this new reactor design was tested experimentally to confirm that the design objective was achieved. This work shows the potential synergies between first principles models for process understanding and CFD models for process prototyping and optimization. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Decontamination of sulfur mustard on manganese oxide nanostructures
Authors: Prasad G. K. , Mahato T. H. , Singh Beer , Pandey P. , Rao A. N. , Ganesan K. , Vijayraghavan R. 
Published: April 2007

AbstractNanostructures made up of restacked manganese oxide nanosheets and nanotubes were tested as reactive sorbents for the detoxification of sulfur mustard, a highly persistent and a deadly chemical warfare agent. The kinetic data was compared with that of the precursor bulk HxMnO2 material and the data show that the agent undergoes hydrolysis and elimination reactions and yields hemisulfur mustard, thiodiglycol, chlorovinylethyl sulfide, divinyl sulfide, and hydroxyvinylethyl sulfide on the surface of the adsorbent made up of nanosheets and tubes; however, it undergoes oxidation reaction and yields sulfoxide of sulfur mustard on the surface of bulk HxMnO2 material. Kinetic data reveal that the adsorbent compiled of manganese oxide nanosheets and nanotubes show a reaction half life of 9.12 h, where the bulk HxMnO2 show the reaction half life of 29.8 h. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Piperazine‐induced airway symptoms: Exposure‐response relationships and selection in an occupational setting
Authors: Hagmar Lars , Bellander Tom , Ranstam Jonas , Skerfving Staffan 
Published: April 2007

AbstractThe heterocyclic secondary amine piperazine is known to cause asthma. In a cohort of 602 workers, employed during the period 1942‐1979, at a chemical industry where piperazine is handled, a study conducted by means of a mailed questionnaire showed a strong exposure‐response relationship as to frequency of work‐related airway symptoms indicating asthma. In the most exposed group about a third of the workers had experienced such symptoms. Age, length of employment, smoking habits, and previous work‐related asthmatic symptoms, but not atopy, modified the response. Further, there was an association between piperazine exposure and chronic bronchitis. In the most exposed group every fourth subject had chronic bronchitis. The frequency was modified by smoking habits; atopy was a confounder. Although many subjects, especially high‐exposed ones, left work because of airway symptoms, there was no difference in occurrence of airway symptoms between former and present employees, ie, no “healthy worker selection” (“survivor population effect”).
In vitro assessment of the fibrogenicity of mineral dusts
Authors: Heppleston A. G. , Kulonen E. , Potila M. 
Published: April 2007

AbstractRelying on in vitro production of the macrophage fibrogenic factor, an attempt was made to quantitate the fibrogenicity of mineral particles. Having determined the optimal conditions by means of quartz, two series of experiments were conducted with respirable coal mine dusts; the first employed artificial mixtures of a mine dust, having a low natural quartz content, with various proportions of quartz, and the second native dusts from European mines.The fibrogenic responses in both series suggest that dust concentration is more important than its composition. Quartz and ash contents of native dusts bore no evident relation to fibrogenicity, high quartz and ash levels sometimes being associated with low collagen levels and vice versa. Comparison with other information disclosed disparities with epidemiology and different experimental assessments. Factors affecting the disarray may well include the neglected lipid response in vivo and individual susceptibility, aspects which do not appear beyond experimental assay.
Serum immunoglobulin levels and humoral immune competence in coalworkers
Authors: Robertson Maura D. , Boyd Janice E. , Collins Heather P. R. , Davis J. M. G. 
Published: April 2007

AbstractSerum immunoglobulin (Ig) levels were measured in 788 coalworkers and 121 nonmining controls for comparison with the radiological category of pneumoconiosis after taking into account age and smoking habit. In addition a simple assessment of humoral immune competence was made by estimating the titre of serum antibody against the common gut commensal Escherichia coli. Smoking was found to depress serum IgA and IgM whilst levels of IgG and IgA increased slightly with age. Men with radiological signs of coalworkers pneumoconiosis (CWP) had significantly raised levels of IgA and IgG with increasing pneumoconiosis category. Even coalworkers with less than category 1 simple pneumoconiosis had raised levels of IgA, suggesting that increased production of this immunoglobulin occurs before radiologically identifiable pathological changes have occurred in the lung tissue. No association between reduced humoral immune competence and radiological category of pneumoconiosis was found. Whether high Ig levels in men exposed to coal dust are merely a passive response to dusted lung tissue or whether they indicate that an immunological process is important in the development of pneumoconiotic lesions remains uncertain.
The accuracy of self‐reported regulatory data: The case of coal mine dust
Authors: Boden Leslie I. , Gold Morris 
Published: April 2007

AbstractCoal‐mine owners are required to measure miner exposures to respirable dust so that compliance with Federal health regulations can be monitored. This study analyzes the problem of possible underreporting of dust exposures. Using two statistical approaches, data for three mining occupations in 54 large underground coal mines during 1976–1978 are examined for evidence of underreporting. First, regression estimates compare dust concentrations reported by coal‐mine owners with those reported by government health inspectors. Then, the statistical distribution of concentrations reported by coal‐mine owners are examined for the size and nature of their deviation from log‐normality. Both approaches suggest widespread underreporting.
Reversible subacute ethylene glycol monomethyl ether toxicity associated with microfilm production: A case report
Authors: Cohen Richard 
Published: April 2007

AbstractThe first reported case of a possible toxic effect of ethylene glycol monomethyl ether (EGME) exposure in the microfilm manufacturing industry is described. Reversible subjective central nervous sytem complaints and asymptomatic hematopoetic effects occurred following inhalation and skin exposure to EGME. Hematopoetic changes occurred at airborne levels which have been associated with reproductive and teratogenic effects in other studies. This finding leads to a recommendation for further research to determine whether or not hematopoetic medical surveillance can provide an indication of not only EGME hematopoetic effects but also an indication of sufficient EGME exposure to affect human reproduction and fetal development.
Lead in finger‐bone analysed in vivo in active and retired lead workers
Authors: Christoffersson J. O. , Schütz A. , Ahlgren L. , Haeger‐Aronsen B. , Mattsson S. , Skerfving S. 
Published: April 2007

AbstractIn 75 active lead workers the median lead level in finger‐bone (bone‐Pb), as determined in vivo by an X‐ray fluorescence method, was 43 μg/g (range < 20–122). In 32 retired workers the median level was even higher, 59 μg/g (range < 20–135), which indicates a slow turnover rate of lead in finger‐bone. This was confirmed in 18 of the “active” workers, in whom bone‐Pb was studied in connection with an exposure‐free period. In spite of a significant decrease in blood‐lead levels (B‐Pb), no systematic change of bone‐Pb occurred. There was an increase of bone‐Pb with time of employment, but with a large interindividual variation. No association was found between bone‐Pb and present B‐Pb in the active lead workers. However, in the retired ones, B‐Pb rose with increasing bone‐Pb. The bone‐lead pool thus causes an “internal” lead exposure.
Exacerbation of coronary artery disease by occupational carbon monoxide exposure: A report of two fatalities and a review of the literature
Authors: Atkins Elisha H. , Baker Edward L. 
Published: April 2007

AbstractThe recent deaths of two workers with coronary artery disease (CAD) following exposure to carbon monoxide (CO) at work reinforced our appreciation of the hazard of this exposure to individuals with preexisting heart disease. Carbon monoxide acts to precipitate ischemia by reducing oxygen delivery to the myocardium. Animal and in vitro experiments suggest that CO may accelerate the development of atherosclerosis, particularly if exposure is in association with other risk factors. Thus, persons with known CAD who are exposed to CO at work are at risk for both the acceleration of the course of the underlying disease and for precipitation of acute ischemia or infarction following excessive exposure. Particular attention should be given to control of CO exposures in light of this hazard. For various reasons, preplacement evaluations or other job selection procedures do not adequately address this hazard. In view of the high prevalence of CAD in the U.S. and the high frequency of workplace exposure to CO, particular attention should be given to control of CO exposure through industrial hygiene measures.
A case‐control study of renal cancer mortality at a texas chemical plant
Authors: Bond Gregory G. , Shellenberger Rita J. , Flores George H. , Cook Ralph R. , Fishbeck William A. 
Published: April 2007

AbstractAn in‐plant case‐control study of 26 renal cancer deaths was conducted to determine whether an occupational exposure may be related to an apparent increase in mortality from this disease observed among a sample of employees at a multiple process chemical production facility. None was found that explained the excess. Elevated odds ratios were identified for employment in the cell maintenance area of chlorine production and with those presumptive exposures considered to occur in this job, asbestos and caustic, but not chlorine. While an association between renal cancer and asbestos has been previously reported, an association with caustic, per se, is not consistent with prior observations made by others. Diminished risk estimates were observed for employment in magnesium production and for exposures in this process to sulfur dioxide and heat. Both the increased and decreased risks, while statistically significant, are based on small numbers of exposed subjects and may be spurious owing to the problem of multiple comparisons.
Saccadic eye movements among copper smelter workers
Authors: Glickman Linda , Valciukas José A. , Lilis Ruth , Weisman Irving 
Published: April 2007

AbstractSaccade accuracy was studied in 87 copper smelter workers. Findings were compared with those obtained in 52 lead‐exposed automobile production workers and 52 controls examined as part of a separate study. Both groups of workers showed a decrease in saccade accuracy compared to controls. Saccade accuracy was reduced in copper smelter workers over 50 years of age compared to automobile production workers in this age group. Decreased saccade accuracy was not correlated with blood lead (Pb‐B), zinc protoporphyrin (ZPP), or urinary arsenic (As‐U) levels among copper smelter workers, but was significantly correlated with both Pb‐B and ZPP in the group of automobile production workers. Saccade accuracy decreased significantly with age and duration of exposure only in the group of copper smelter workers. Complex exposures to lead and other toxic agents present in the smelter may account for the reduction in saccade accuracy among copper smelter workers.
Animal studies and prediction of human tumors can be aided by graphical sorting of animal data: Neoplastic risk from B(a)P, benzene, benzidine, and chromium
Authors: Jones Troyce D. , Walsh P. J. 
Published: April 2007

AbstractThis work is a graphical study of all known dose‐response data for neoplasia induced by B(a)P, benzene, benzidine, and chromium administered to test animals. Doses are put in units of lifetime intake given in micromoles of chemical per kilogram body weight, and responses are in percent increased effect per unit dose. Space limitations do not permit experiment‐by‐experiment critiques; however, computer graphics have been used to compare the relationship of any individual dose‐response point estimate to other such point estimates for the chemical of interest. Graphics are also used to study variability resulting from different experimental parameters such as species, route of intake, number of treatments, pathological classification of neoplasia, etc. Graphical sorting, according to various physical and biological classification parameters, permits one to judge, from visual inspection, such questions as whether mice as a species are more sensitive than rats as a species, whether intravenous injection is generally more effective than inhalation, whether a single well‐defined dose‐response function, which ignores these classification parameters, can be evaluated numerically from the composite data base deriving from all oncogenic studies with a given chemical, etc.
Mortality studies of dockyard workers (longshoremen) in italy
Authors: Bonassi S. , Ceppi M. , Puntoni R. , Valerio F. , Vercelli M. , Belli S. , Biocca M. , Comba P. , Ticchiarelli L. , Mariotti F. , Taddeo D. , Zuccherelli D. , Casalini A. , Perini C. , Nelli L. , Sansoni G. , Pupp N. , Farina M. , Luciani A. 
Published: April 2007

AbstractA polycentric mortality study was performed in five Italian harbours: Savona, Marina di Carrara, Livorno, Civitavecchia, and Ravenna. The cohort included active and retired workers (longshoremen), who had been employed between 1960 and 1981. Causes of death were ascertained from death certificates; expected numbers of deaths were generated from age, sex, calendar year, and cause‐specific national mortality rates. A low overall mortality was found, which is in agreement with procedures of health selection, typical of physically demanding jobs; an excess of lung cancer was, however, found in four out of five harbours.
A respiratory epidemiological study of stevedores intermittently exposed to asbestos in a South African port
Authors: Myers J. E. , Garisch D. , Myers H. S. , Cornell J. E. , Rwexu R. D. 
Published: April 2007

AbstractThe prevalence of asbestosis in stevedores intermittently transporting crocidolite asbestos in a South African port was found to be 30% in a cross‐sectional survey. Diagnostic criteria are discussed in terms of the low index of suspicion for industrial diseases, the high probability of missing slight radiological changes, and the attribution of radiological lesions to other diseases, particularly tuberculosis, in a high prevalence area. Results are compared with other studies. Asbestosis was not associated with tuberculosis. Smoking was not significantly associated with asbestosis, other respiratory signs and symptoms, or radiological abnormality.
An epidemiologic surveillance program for evaluating occupational reproductive hazards
Authors: Wong Otto , Morgan Robert W. , Whorton M. Donald 
Published: April 2007

AbstractA noninvasive and inexpensive epidemiologic program for evaluating the possible effects of occupational exposures on fertility is proposed. This surveillance program utilizes reproductive information obtainable from a short questionnaire (1–2 pages in length) or directly from existing medical, employment, or insurance records, and results can be generated readily on a routine basis. This program examines the reproductive experience of the exposed workers in terms of live births compared with that of the US general population with the proper statistical adjustments. It calculates the standardized birth ratios (SBR), adjusting for maternal age, parity, calendar time, and race. Such an analysis will detect whether there is a significant decrease in fertility among a group of employees, and is, therefore, a useful surveillance tool. The proposed method should be viewed as a mechanism to provide an early signal for any potential hazard and to direct priority for other more in‐depth epidemiologic or physiologic studies. The procedure is illustrated with data from individuals exposed to EDB, DBCP, and waste‐water treatment plant processes. The method can be modified to compare the reproductive performance of an exposed group to that of an internal control group. With an internal control group, additional confounding factors can be taken into consideration. The relative merits of this approach compared to another method of fertility evaluation, semen analysis, are discussed.
Low level benzene exposure in sweden: Effect on blood elements and body burden of benzene
Authors: Berlin Maths 
Published: April 2007

AbstractMeasurements for benzene exposure were performed for different work places. In addition, breath benzene concentrations were measured in different occupations in order to establish toxico‐kinetics of benzene in man; chromosomal aberrations in lymphocytes of exposed workers were also examined. Smoking appears to result in a large increase in benzene concentration in exhaled breath. The smoke from one cigarette contains 60‐80 μg of benzene. It was found that exposure levels of 10 ppm are rather uncommon among workers handling gasoline or gasoline equipment. It was concluded that the gasoline load of road tankers cannot be responsible for chromosome changes of the driver, as milk truck drivers showed the same changes. These results did not prove that benzene was the cause of the observed changes. Smoking is the confounding factor, with a potency of at least the same order of magnitude as benzene. In addition, our present knowledge about mechanisms of benzene is not sufficiently developed to permit quantitative conclusions as to the human health risks.
Benzene: Standards, occurrence, and exposure
Authors: Holmberg Bo , Lundberg Per 
Published: April 2007

AbstractThe national occupational standard values for benzene are 10 ppm for Australia, 10 ppm for Denmark, 10 ppm for Finland, 10 ppm for Japan, 10 ppm for The Netherlands, 10 ppm for the United States, and 5 ppm for Sweden; in the Federal Republic of Germany the technical guideline value is 8 ppm. Crude mineral oil contains benzene as a natural constituent of approximately 0.1%. Gasoline in Sweden may contain 4–5% benzene by volume. The 8‐hour time‐weighted average (TWA) exposure levels of Swedish petroleum refinery workers vary between 0.1 to 1 mg benzene/m3 in air. The exposures of benzene in various other occupations were measured and described. Other environmental exposures to benzene may have their origin in pyrolysis, such as tobacco smoking and burning of substances such as polyvinylchloride.
Benzene exposure in the United States 1978–1983: An overview
Authors: Runion H. E. , Scott L. M. 
Published: April 2007

AbstractDue to the interest in reducing the benzene exposure limit from 10 to 1 ppm, the benzene exposure data collected since 1977 were compiled and evaluated. Some 38,000 data points representing either time‐weighted air samples or persons exposed were collected from five industries which produce and/or use benzene and two government organizations. Of the reported data, 87% represented exposure levels of 1.0 ppm or less. Petroleum and chemical operations where elevated exposure levels were reported included petrochemical and bulk loading operations. Benzol and by‐product plants in the iron and steel industry showed similar elevated results.