bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the complexation behavior between humic acid and UO22+with fluorescence spectroscopy and its mixture analysis
Authors: Saito T. , Nagasaki S. , Tanaka S.
Published: November 2005

The fluorescence of humic acid (HA) is quenched due to its complexation with UO22+ions, leading to the evolutionary quenched intensity profile (quenching profile) as a function of UO22+concentration. This quenching behavior was investigated using 3-dimensional (3D) and synchronous (SyF) fluorescence spectroscopy. The quenching profile obtained by means of SyF spectroscopy was deconvoluted by SIMPLISMA, which is an interactive self-modeling mixture analysis method. Two sites, which contribute to the fluorescence of HA and whose fluorescence is quenched due to its complexation with UO22+, have been extracted, and the quenching profile was resolved to the fluorescence intensity profiles of these sites and the corresponding spectra. Based on these intensity profiles, the apparent stability constant (logKapp) and the concentration of site (CL) were evaluated for each site, using nonlinear least-squares regression to the Multisite Ryan-Weber Model.
Adsorption studies of zinc ions on barium titanate from aqueous solution
Authors: Guin R. , Das S. K. , Saha S. K.
Published: November 2005

Adsorption of Zn(II) ions on barium titanate has been studied as a function of concentration of Zn(II) (1.0 ×−5–5.0 × 10−7M), temperature (281–313 K) and pH (4–8) of the adsorptive solution using65Zn tracer and γ-ray spectroscopy. The adsorption process was found to obey the first order rate law and the Freundlich adsorption isotherm for the range of concentration studied. The uptake increases from 32 to 70% with the increase in dilution (from 1.0 × 10−5to 5.0 × 10−7M). The extent of adsorption also increases with increasing temperature and pH of solution. The activation energy for the process was determined to be 12.3 kJ mol−1. The removal of Zn(II) ions by barium titanate appears to be endothermic and irreversible.
The enrichment of magnesium isotopes by AM15C5 bonded ion exchanger
Authors: Kim D. W. , Kang B. M.
Published: November 2005

Magnesium isotope enrichment was investigated by chemical ion exchange with a synthesized 2′-aminomethyl-15-crown-5(AM15C5) bonded Merrifield peptide resin using elution chromatography. The capacity of the novel crown ion exchanger was found to be 2.3 meq/g dry resin. The heavier isotopes of magnesium were enriched in the solution phase, while the lighter isotopes were enriched in the resin phase. The separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assays. The separation factors of 24Mg2+–25Mg2+, 24Mg2+–26Mg2+, and 25Mg2+–26Mg2+ isotope pair fractionations were 1.013, 1.024, and 1.012, respectively.
Fission neutron spectrum averaged cross sections of some threshold reactions on titanium: production feasibility of 45Ti in a nuclear reactor
Authors: Fatima I. , Zaidi Jamshed H. , Qureshi I. H. , Subhani M. S.
Published: November 2005

Systematic studies on fission neutron spectrum averaged cross sections of some threshold reactions like (n, 2n), (n, p) and (n, α) on titanium were carried out using the activation technique in combination with radiochemical separations and high-resolution γ-ray spectroscopy. Special attention was paid to the formation 45Ti via the 46Ti(n, 2n)45Ti reaction since 45Ti labeled compounds are potentially important radiopharmaceuticals. At a fast flux neutron density of 7.5 × 1013 cm−2 s−1 and using 100% enriched 46Ti target, 8.58 MBq saturation activity of 45Ti per batch can be produced. Due to rather low activity and low specific activity the procedure is not feasible from medical application point of view.
Adsorption of uranium on halloysite
Authors: Kilislioglu A. , Bilgin B.
Published: November 2005

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin–Radushkevich (D–R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D–R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature.
Chromatographic separation of lithium and magnesium isotopes by manganese(IV) oxide
Authors: Kim D. W. , Kim C. S. , Lee N. S. , Ryu H. I.
Published: November 2005

Separation of lithium and magnesium isotopes was investigated by chemical ion exchange with a manganese(IV) oxide using an elution chromatography. The capacity of manganese(IV) oxide was 0.5 meq/g. Two molar sodium acetate solution was used as an eluent. The heavier isotopes of lithium and magnesium were enriched in the solution phase, while the lighter isotopes were enriched in the MnO2 phase. The separation factors were determined according to the method of Glueckauf from the elution curves and isotopic assays. The separation factor of lithium isotopes was 1.026. In addition, the separation factors of 24Mg2+–25Mg2+, 24Mg2+–26Mg2+, and 25Mg2+–26Mg2+ isotope pair fractionations were 1.012, 1.022, and 1.011, respectively. The isotope separation system in this work can be explained by the fact that the hydration and isotope mass effects are more significant.
U.S.-Russian Relations and the North Korean Crisis: A Role for the Russian Far East?
Authors: Moltz James Clay
Published: November 2005

Because of its energy reserves and long history of economic links with North Korea, the Russian Far East could provide useful incentives needed to help convince Pyongyang to abandon its nuclear program. For this reason, the United States should begin crafting a regionally based strategy that includes Russia.
Assessing Self-Renewal and Differentiation in Human Embryonic Stem Cell Lines
Authors: Cai Jingli , Chen Jia , Liu Ying , Miura Takumi , Luo Yongquan , Loring Jeanne F. , Freed William J. , Rao Mahendra S. , Zeng Xianmin
Published: November 2005

Like other cell populations, undifferentiated human embryonic stem cells (hESCs) express a characteristic set of proteins and mRNA that is unique to the cells regardless of culture conditions, number of passages, and methods of propagation. We sought to identify a small set of markers that would serve as a reliable indicator of the balance of undifferentiated and differentiated cells in hESC populations. Markers of undifferentiated cells should be rapidly downregulated as the cells differentiate to form embryoid bodies (EBs), whereas markers that are absent or low during the undifferentiated state but that are induced as hESCs differentiate could be used to assess the presence of differentiated cells in the cultures. In this paper, we describe a list of markers that reliably distinguish undifferentiated and differentiated cells. An initial list of approximately 150 genes was generated by scanning published massively parallel signature sequencing, expressed sequence tag scan, and microarray datasets. From this list, a subset of 109 genes was selected that included 55 candidate markers of undifferentiated cells, 46 markers of hESC derivatives, four germ cell markers, and four trophoblast markers. Expression of these candidate marker genes was analyzed in undifferentiated hESCs and differentiating EB populations in four different lines by immunocytochemistry, reverse transcription–polymer-ase chain reaction (RT-PCR), microarray analysis, and quantitative RT-PCR (qPCR). We show that qPCR, with as few as 12 selected genes, can reliably distinguish differentiated cells from undifferentiated hESC populations.
Rapid Generation of Stable Transgenic Embryonic Stem Cell Lines Using Modular Lentivectors
Authors: Suter David M. , Cartier Laetitia , Bettiol Esther , Tirefort Diderik , Jaconi Marisa E. , Dubois-Dauphin Michel , Krause Karl-Heinz
Published: November 2005

Generation of stable transgenic embryonic stem (ES) cell lines by classic transfection is still a difficult task, requiring time-consuming clonal selection, and hampered by clonal artifacts and gene silencing. Here we describe a novel system that allows construction of lentivectors and generation of stable ES cell lines with > 99% transgene expression within a very short time frame. Rapid insertion of promoters and genes of interest is obtained through a modular recombinational cloning system. Vectors contain central polypurine tract from HIV-1 element and woodchuck hepatitis virus post-transcriptional regulatory element as well as antibiotic resistance to achieve optimal and homogenous transgene expression. We show that the system 1) is functional in mouse and human ES cells, 2) allows the generation of ES cells expressing genes of interest under the control of ubiquitous or tissue-specific promoters, and 3) allows ES cells expressing two constructs through selection with different antibiotics to be obtained. The technology described herein should become a useful tool in stem cell research.
A Three-Dimensional Model to Study the Epigenetic Effects Induced by the Microenvironment of Human Embryonic Stem Cells
Authors: Postovit Lynne-Marie , Seftor Elisabeth A. , Seftor Richard E.B. , Hendrix Mary J.C.
Published: November 2005

New methods of study are necessary to define the homeostatic mechanisms that regulate stem cell properties and to determine the possible epigenetic influence of the stem cell microenvironment on the phenotype of tumor cells. We recently demonstrated that the tumorgenicity of aggressive cutaneous melanoma cells can be abrogated by the zebrafish embryonic microenvironment. We have developed a three-dimensional (3D) model, as a corollary of these findings, that allows melanoma cells to be exposed to the microenvironment of human embryonic stem cells (hESCs). Using this methodology, we determined that hESC microenvironments can dramatically influence the behavior of aggressive melanoma cells. Specifically, exposure of tumor cells to H1- or HSF-6-hESC matrices induced a melanocyte-like phenotype with the ability to form colonies similar to hESCs. Furthermore, melanoma cells were less invasive after culture on hESC microenvironments. These findings demonstrate the utility of this 3D model for studying the unique factors deposited by hESCs and for investigating the epigenetic effects that stem cell microenvironments may have on tumor progression.
Root‐Knot Nematode Resistant Cowpea Cover Crops in Tomato Production Systems
Authors: Roberts P. A. , Matthews W. C. , Ehlers J. D.
Published: November 2005

Root‐knot nematodes, Meloidogyne spp., are serious pests of many crops worldwide. Recent limitations on the use of nematicides have enhanced the need to develop alternative management strategies, including host plant resistance. This study was conducted to determine the effectiveness of nematode‐resistant cowpea [Vigna unguiculata (L.) Walp.] genotypes used as cover crops for suppressing populations of M. incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood and protecting susceptible tomato (Lycopersicon esculentum Mill.) grown in rotation. In six field experiments, susceptible and resistant cowpea was grown to flowering stage and the dried tops incorporated or not incorporated into the soil. These treatments were compared to wet and dry fallowing and were conducted on nematode‐infested and noninfested plots. The experiments were conducted in the Coachella and San Joaquin Valleys, California. Resistance conferred by genes Rk and Rk2 reduced loss of cowpea biomass and M. incognita soil populations and partially suppressed M. javanica compared with susceptible cowpea, but not as effectively as fallow treatments. Incorporation of cowpea tops into the soil promoted tomato growth irrespective of nematode presence. On infested plots, tomato fruit yield was higher following growth and incorporation of resistant cowpea compared with growth and incorporation of susceptible cowpea or nonincorporation of cowpea and fallow treatments. We conclude that root‐knot nematode‐resistant cowpea is an effective cover crop for protecting susceptible vegetable crops grown under irrigation, and its beneficial effects are enhanced by incorporation of its green biomass.
Plant‐to‐Plant Variability in Corn Production
Authors: Martin K. L. , Hodgen P. J. , Freeman K. W. , Melchiori Ricardo , Arnall D. B. , Teal R. K. , Mullen R. W. , Desta K. , Phillips S. B. , Solie J. B. , Stone M. L. , Caviglia Octavio , Solari Fernando , Bianchini Agustin , Francis D. D. , Schepers J. S. , Hatfield J. L. , Raun W. R.
Published: November 2005

Corn (Zea mays L.) grain yields are known to vary from plant to plant, but the extent of this variability across a range of environments has not been evaluated. This study was initiated to evaluate by‐plant corn grain yield variability over a range of production environments and to establish the relationships among mean grain yield, standard deviation, coefficient of variation, and yield range. A total of forty‐six 8‐ to 30‐m corn transects were harvested by plant in Argentina, Mexico, Iowa, Nebraska, Ohio, Virginia, and Oklahoma from 2002 to 2004. By‐plant corn grain yields were determined, and the average individual plant yields were calculated. Over all sites in all countries and states, plant‐to‐plant variation in corn grain yield averaged 2765 kg ha−1 (44.1 bu ac−1). At the sites with the highest average corn grain yield (11478 and 14383 kg ha−1, Parana Argentina, and Phillips, NE), average plant‐to‐plant variation in yield was 4211 kg ha−1 (67 bu ac−1) and 2926 kg ha−1 (47 bu ac−1), respectively. As average grain yields increased, so did the standard deviation of the yields obtained within each row. Furthermore, the yield range (maximum corn grain yield minus the minimum corn grain yield per row) was found to increase with increasing yield level. Regardless of yield level, plant‐to‐plant variability in corn grain yield can be expected and averaged more than 2765 kg ha−1 over sites and years. Averaging yield over distances >0.5 m removed the extreme by‐plant variability, and thus, the scale for treating other factors affecting yield should be less than 0.5 m. Methods that homogenize corn plant stands and emergence may decrease plant‐to‐plant variation and could lead to increased grain yields.
A Multi‐Tactic Approach to Manage Weed Population Dynamics in Crop Rotations
Authors: Anderson Randy L.
Published: November 2005

No‐till systems have enabled producers to change crop rotations in the semiarid Central Great Plains. Previously, winter wheat (Triticum aestivum L.)–fallow was the prevalent rotation; now producers grow warm‐season crops along with winter wheat and fallow. Initially, weed management was difficult in no‐till rotations. However, an ecological approach to weed management, which integrates knowledge of weed population dynamics with cultural tactics and long‐term planning, has enabled producers to control weeds with 50% less herbicides. This article explains the cultural tactics and ecological reasoning that led to this successful approach; our goal is to provide insight and ideas for other scientists and producers to plan multi‐tactic weed management. The ecological approach emphasizes three goals related to weed population dynamics: enhancing natural loss of weed seeds in soil, reducing weed seedling establishment, and minimizing seed production by established plants. Cultural tactics used in this approach can be grouped into five categories: rotation design, crop sequencing, no‐till, crop residue management, and competitive crop canopies. Success of the approach requires cultural tactics in each category.
Continuous Soil Carbon Dioxide and Oxygen Measurements and Estimation of Gradient‐Based Gaseous Flux
Authors: Turcu Vasile E. , Jones Scott B. , Or Dani
Published: November 2005

The magnitude and dynamics of soil gaseous fluxes play critical roles in the global gas balance; yet, these processes are not captured at sufficient temporal resolution by standard methods based on periodic sampling and surface chamber measurements. A novel method for continuous measurement of soil surface gas fluxes based on subsurface CO2 and O2 concentration gradient measurements was developed. We tested the gradient‐based method under steady‐ and transient‐state soil water content and temperature conditions and compared results with a state‐of‐the‐art surface chamber CO2 flux system. The new aspects of the method include fast‐response sensors installed in the soil profile providing continuous record of concentration gradients coupled with concurrent estimates of water content‐dependent gaseous diffusion coefficient enabling calculation of surface gaseous fluxes. Low‐cost infrared sensors were used for CO2 concentration measurements, and galvanic cells for O2 measurements. An imposed CO2 concentration gradient in a dry soil column resulted in a quasilinear CO2 concentration profile and surface CO2 flux in agreement with chamber‐measured fluxes. A series of continuous concentration measurements under variable water content conditions and wetting events showed agreement with surface chamber measurements. Within several days of surface wetting, soil CO2 concentrations attained 10 mL L−1, one order of magnitude higher than ambient concentrations, whereas O2 concentrations decreased. The gradient‐based approach minimizes soil surface perturbations and provides insights into subsurface soil CO2 and O2 dynamics and the distribution and magnitude of soil respiration processes as related to soil environmental factors. The subsurface gradient‐based measurement system represents an order‐of‐magnitude reduction in cost compared with research‐grade surface chamber devices.
Removal of Carbon Tetrachloride from a Layered Porous Medium by Means of Soil Vapor Extraction Enhanced by Desiccation and Water Table Reduction
Authors: Oostrom M. , Dane J. H. , Wietsma T. W.
Published: November 2005

A two‐dimensional flow cell experiment was conducted to study the removal of the carbon tetrachloride component of a DNAPL mixture from a layered porous medium through soil vapor extraction (SVE) with moist and dry air. A dual‐energy γ radiation system was used at various times to non‐intrusively determine fluid saturations. The mixture, which contained the volatile organic carbon tetrachloride, mimics the DNAPL disposed at the Hanford Site in Washington State. The flow cell, which is 100 cm long, 75 cm high and 5.5 cm wide, was packed with two sloped coarse sand and two sloped silt layers in an otherwise uniform matrix of medium‐grained sand. A V‐shaped fine sand layer was placed at the bottom of the flow cell to prevent DNAPL from exiting the flow cell. The water table was located 2 cm from the bottom, creating variably saturated conditions. A 500‐mL spill was introduced at the top of the flow cell from a small source area. It was observed that the DNAPL largely by‐passed the silt layers but easily moved into the coarse sand layers. Residual DNAPL was formed in the medium‐grained sand matrix. The DNAPL caused a distinct reduction of the capillary fringe. Most of the DNAPL ended up in a pool on top of the V‐shaped fine sand. Through four treatments with moist air soil vapor extraction, most residual carbon tetrachloride was removed from the medium‐grained matrix and the coarse sand layers. However, soil vapor extraction with moist air was not able to remove the carbon tetrachloride from the silt layers and the pool. Through a water table reduction and subsequent soil vapor extraction with dry air, the carbon tetrachloride in the silt layers and the pool was effectively removed. Based on γ measurements and carbon tetrachloride vapor concentration data, it was estimated that after the final remediation treatment, almost 90% of the total mass was removed.
Bias in Ponded Infiltration Estimates Due to Sample Volume and Shape
Authors: Wuest Stewart B.
Published: November 2005

Estimates of saturated and unsaturated water flow in soil are important for predictions of infiltration, runoff, and solute transport. Previous research indicates that ponded infiltration estimates are influenced by the volume or cross‐sectional area of the measurement. Our study compared quasi‐steady infiltration measurements made using 20‐, 30‐, and 45‐cm‐diameter cylinders driven 25 cm deep into 56 field plots under diverse agricultural management practices. Mean infiltration rate increased from 50, to 81, to 95 mm h−1 as diameter increased. Standard deviation and range also increased with diameter. All three diameters produced lognormal data distributions. These results indicate that increasing the sample area is not equivalent to pooling of many smaller samples, which would have produced the same mean but with a lower variance. Follow‐up experiments with a double‐ring configuration or a divider placed in the center of a 45‐cm cylinder demonstrated that adding vertical barriers reduced infiltration even when the total infiltration area was unchanged. A pulse of dye introduced 10 min before removing the ponded water showed an extensive network of dyed flow pathways in all but the slowest infiltration situations. The pathways were not associated with visible macropores. Careful consideration should be given to the dimensions of samples used to estimate saturated and possibly unsaturated flow from infiltration experiments.
Estimation of net‐costs for prevention of occupational low back pain: Three case studies from the US
Authors: Lahiri Supriya , Gold Judith , Levenstein Charles
Published: November 2005

Background

Occupational low back pain (OLBP) is widespread in industrialized societies. We present a model to estimate the net economic costs of investments in ergonomic interventions at the company level to reduce work‐related low back pain.

Methods

Costs of interventions are defined by incorporating not only the costs of investment of equipment and labor, but also by taking into account the avoided costs of lost work time, medical care costs, and productivity improvements. In the net‐cost model, all costs are annualized and are calculated at the level of an individual organization. Three case studies have been performed based on data from three companies in the manufacturing sector of the United States using the above approach.

Results

The net‐cost estimates for the three case studies consistently show that ergonomic interventions applied appropriately can result in substantial cost savings for the companies.

Conclusions

Although generalizing on the basis of three case studies is not ideal, our analyses show that it might be in the economic interest of management to play a more active role to prevent back pain. Gathering useful retrospective cost data, even on interventions deemed effective by corporate innovators, proved to be extremely difficult. We conclude that it is essential to incorporate a protocol for collecting cost and effectiveness data in the standard operating procedures of ergonomists and companies introducing such innovation. We intend to validate the net‐cost model for the monitoring and reporting of such data through prospective studies in a variety of industrial settings and in countries at various stages of economic development. Am. J. Ind. Med. 48:530–541, 2005. © 2005 Wiley‐Liss, Inc.
Review of estimates of the global burden of injury and illness due to occupational exposures
Authors: Driscoll Timothy , Takala Jukka , Steenland Kyle , Corvalan Carlos , Fingerhut Marilyn
Published: November 2005

Background

Over the last decade, there have been several attempts to estimate the global burden of ill health due to work activity. The most recent of these is the Comparative Risk Assessment (CRA) project of the World Health Organization.

Methods

Published estimates of global burden of injury and disease due to occupational factors were summarized, compared, and contrasted with the aim of putting the CRA estimates into context, identifying the most reliable and appropriate estimate for total burden due to occupational risks, and making recommendations regarding future work.

Results

The best estimate of global work‐related deaths of workers is approximately two million per year, with disease responsible for the vast majority of these, but even this is likely to be a considerable underestimate of the true number of deaths because of shortcomings in the available data.

Conclusions

The CRA estimates of burden due to individual risk factors appear appropriate for the limited number of exposures and conditions included, but are a major underestimate of the overall number of work‐related deaths at a global level due to exclusion of risk factors because of data limitations. Improvements in global estimates are likely to come from the use of different methodologies and improvements in the availability and use of local data. Am. J. Ind. Med. 48:491–502, 2005. © 2005 Wiley‐Liss, Inc.
The global burden of non‐malignant respiratory disease due to occupational airborne exposures
Authors: Driscoll Timothy , Nelson Deborah Imel , Steenland Kyle , Leigh James , Concha‐Barrientos Marisol , Fingerhut Marilyn , Prüss‐Üstün Annette
Published: November 2005

Background

Occupational non‐malignant respiratory disease arises from exposure of workers to airborne agents, mostly particulate or dusts. We describe the worldwide mortality and morbidity from asthma, chronic obstructive pulmonary disease (COPD), and pneumoconioses arising from these occupational exposure and focus on cases reported in the year 2000.

Methods

The proportions of workers exposed to the agents, and their levels of exposure, were estimated using workforce data and the CAREX (CARcinogen EXposure) database. These were combined with relative risk measures (for asthma and COPD) or absolute risk measures (for the pneumoconioses) to develop estimates of deaths, disability‐adjusted life years (DALYs) and attributable fraction (for asthma and COPD).

Results

There were an estimated 386,000 deaths (asthma: 38,000; COPD: 318,000; pneumoconioses: 30,000) and nearly 6.6 million DALYS (asthma: 1,621,000; COPD: 3,733,000, pneumoconioses: 1,288,000) due to exposure to occupational airborne particulates.

Conclusions

Occupational airborne particulates are an important cause of death and disability worldwide. Am. J. Ind. Med. 48:432–445, 2005. © 2005 Wiley‐Liss, Inc.
The global burden of selected occupational diseases and injury risks: Methodology and summary
Authors: Nelson Deborah Imel , Concha‐Barrientos Marisol , Driscoll Timothy , Steenland Kyle , Fingerhut Marilyn , Punnett Laura , Prüss‐Üstün Annette , Leigh James , Corvalan Carlos
Published: November 2005

Background

Around the globe, work has a heavy impact on health. To better advise policy makers, we assessed the global burden of disease and injury due to selected occupational hazards. This article presents an overview, and describes the methodology employed in the companion studies.

Methods

Using the World Health Organization (WHO) Comparative Risk Assessment methodology, we applied relative risk measures to the proportions of the population exposed to selected occupational hazards to estimate attributable fractions, deaths, and disability‐adjusted life years (DALYs). Numerous occupational risk factors had to be excluded due to inadequate global data.

Results

In 2000, the selected risk factors were responsible worldwide for 37% of back pain, 16% of hearing loss, 13% of chronic obstructive pulmonary disease (COPD), 11% of asthma, 8% of injuries, 9% of lung cancer, and 2% of leukemia. These risks at work caused 850,000 deaths worldwide and resulted in the loss of about 24 million years of healthy life. Needlesticks accounted for about 40% of Hepatitis B and Hepatitis C infections and 4.4% of HIV infections in health care workers.

Conclusions

Exposure to occupational hazards accounts for a significant proportion of the global burden of disease and injury, which could be substantially reduced through application of proven risk prevention strategies. Am. J. Ind. Med. 48:400–418, 2005. © 2005 Wiley‐Liss, Inc.
The cost effectiveness of occupational health interventions: Prevention of silicosis
Authors: Lahiri Supriya , Levenstein Charles , Nelson Deborah Imel , Rosenberg Beth J.
Published: November 2005

Background

The failure to recognize occupational health as an economic phenomenon limits the effectiveness of interventions ostensibly designed to prevent disease and injury. Hence, consideration of economic efficiency is essential in the evaluations of interventions to reduce hazardous working conditions. In this paper, we present an analysis of the cost effectiveness of alternative means of preventing silicosis.

Methods

To evaluate the cost effectiveness of specific interventions for the prevention of occupationally induced silicosis, we have used the simulation models based on the generalized cost‐effectiveness analysis (GCEA) developed by the WHO‐CHOICE initiative for two representative subregions namely AMROA (Canada, United States of America), and WPROB1 (China, Korea, Mongolia).

Results

In both of the two subregions, engineering controls are the most cost effective with ratios varying from $105.89 per healthy year or disability adjusted life year saved in AMROA to approximately $109 in WPROB1. In the two subregions, the incremental cost‐effectiveness ratio of engineering controls (EC) looks most attractive. Although dust masks (DM) look attractive in terms of cost, the total efficacy is extremely limited.

Conclusions

To the extent that this analysis can be generalized across other subregions, it suggests that engineering control programs would be cost effective in both developed and developing countries for reducing silica exposure to save lives. Note that this analysis understates health benefits since only silicosis and not all silica‐related diseases are considered. Am. J. Ind. Med. 48:503–514, 2005. © 2005 Wiley‐Liss, Inc.
The global burden due to occupational injury
Authors: Concha‐Barrientos Marisol , Nelson Deborah Imel , Fingerhut Marilyn , Driscoll Timothy , Leigh James
Published: November 2005

Background

Occupational injuries are a public health problem, estimated to kill more than 300,000 workers worldwide every year and to cause many more cases of disability. We estimate the global burden of fatal and non‐fatal unintentional occupational injuries for the year 2000.

Methods

The economically active population (EAP) of about 2.9 billion workers was used as a surrogate of the population at risk for occupational injuries. Occupational unintentional injury fatality rates for insured workers, by country, were used to estimate WHO regional rates. These were applied to regional EAP to estimate the number of deaths. In addition to mortality, the disability‐adjusted life years (DALYs) lost, which measure both morbidity and mortality, were calculated for 14 WHO regions.

Results

Worldwide, hazardous conditions in the workplace were responsible for a minimum of 312,000 fatal unintentional occupational injuries. Together, fatal and non‐fatal occupational injuries resulted in about 10.5 million DALYs; that is, about 3.5 years of healthy life are lost per 1,000 workers every year globally. Occupational risk factors are responsible for 8.8% of the global burden of mortality due to unintentional injuries and 8.1% of DALYs due to this outcome.

Conclusions

Occupational injuries constitute a substantial global burden. However, our findings greatly underestimate the impact of occupational risk factors leading to injuries in the overall burden of disease. Our estimates could not include intentional injuries at work, or commuting injuries, due to lack of global data. Additional factors contributing to grave underestimation of occupational injuries include limited insurance coverage of workers and substantial under‐reporting of fatal injuries in record‐keeping systems globally. About 113,000 deaths were probably missed in our analyses due to under‐reporting alone. It is clear that known prevention strategies need to be implemented widely to diminish the avoidable burden of injuries in the workplace. Am. J. Ind. Med. 48:470–481, 2005. © 2005 Wiley‐Liss, Inc.
Estimating the global burden of low back pain attributable to combined occupational exposures
Authors: Punnett Laura , Prüss‐Ütün Annette , Nelson Deborah Imel , Fingerhut Marilyn A. , Leigh James , Tak SangWoo , Phillips Sharonne
Published: November 2005

Background

There is little information about the global burden of non‐traumatic low back pain (LBP) attributable to the effects of physical and psychosocial occupational stressors.

Methods

Based on a review of the epidemiological evidence, occupation‐specific relative risks were used to compute attributable proportions by age, gender, and geographical sub‐region for the economically active population aged 15 and older. The reference group was professional/administrative workers; other risk categories were Low, clerical and sales; Moderate, operators (production workers) and service; and High, farmers.

Results

Worldwide, 37% of LBP was attributed to occupation, with twofold variation across regions. The attributable proportion was higher for men than women, because of higher participation in the labor force and in occupations with heavy lifting or whole‐body vibration. Work‐related LBP was estimated to cause 818,000 disability‐adjusted life years lost annually.

Conclusions

Occupational exposures to ergonomic stressors represent a substantial source of preventable back pain. Specific research on children is needed to quantify the global burden of disease due to child labor. Am. J. Ind. Med. 48:459–469, 2005. © 2005 Wiley‐Liss, Inc.
Determination of the solubility of a monomer in water by multiple headspace extraction gas chromatography
Authors: Chai X.‐S. , Hou Q. X. , Schork F. J.
Published: November 2005

In water‐based polymerization (suspension, microsuspension, emulsion, miniemulsion, and microemulsion polymerization), the solubility of the monomer in the aqueous phase can have profound effects on the final polymer product. This article demonstrates a novel method for the determination of monomer solubility in water with headspace gas chromatography (GC). In this method, an excess amount of an organic solute of interest was added into a closed headspace vial containing a given volume of water. The organic solute and water in the vial was well mixed by strong hand shaking; then, the equilibrated vapor solute in the vial at a desired temperature was measured by headspace GC with a multiple headspace extraction mode. In each headspace extraction, a part of the vapor phase in the vial was vented for GC analysis and replaced with an inert gas. The excess amount of solute in aqueous solution was eventually removed from the vial after multiple headspace extractions, and the solute concentration in water reached its saturation point. After that point, the concentration of the solute in the vapor dramatically decreased in each subsequent headspace extraction. By plotting vapor concentration versus headspace extraction number, we determined the transition point. The vapor concentration at this point corresponded to the solute solubility, which was calculated through a calibration. This method was very simple and automated; it could easily be used for organic solute solubility measurement at an elevated temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1296–1301, 2006
Thermal diffusivity of polyolefins by temperature wave analysis
Authors: Chang H. J. , Morikawa J. , Hashimoto T.
Published: November 2005

The thermal diffusivities of 25 kinds of polyolefin films, including high‐density polyethylene, low‐density polyethylene, linear low‐density polyethylene, polypropylene, 4‐methylpentene, and ethylene–octene copolymer, were determined by temperature wave analysis in a continuous temperature scan. The thermal diffusivity decreased with increasing temperature, and the temperature dependence was steeper in the solid state than in the melt state. A supercooling phenomenon was observed in the crystallization process during cooling. The thermal diffusivity of polyethylene in the solid state was in a good correlation with the density at room temperature, and a higher temperature coefficient was observed in high‐density polyethylene with a higher thermal diffusivity. The influence of the catalyst system on the thermal diffusivity was also observed in the ethylene–octene copolymer. The thermal diffusivity was sensitive to the precise change in the microstructure of the crystalline polyolefin, which was influenced not only by the chemical structure but also by the thermal history. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1104–1110, 2006
Preparation of soap‐free cationic emulsion using polymerizable surfactant
Authors: Jin Liqiang , Liu Zonglin , Xu Qinghua , Li Yanchun
Published: November 2005

A kind of polymerizable surfactant, methacryloyloxyethylhexadecyldimethylammonium bromide (DMHB) was used to synthesis soap‐free cationic emulsion with styrene (St), methyl methacrylate (MMA), and methacryloyloxyethyltrimethylammonium chloride (MATMAC) by emulsion polymerization using 2,2′‐azobis(isobutylamidine hydrochloride) (AIBA) as a cationic initiator. The effects of polymerizable surfactant concentration, initiator concentration, and reaction temperature on the conversion of monomer were investigated. The results indicated that the rate of polymerization could be expressed as Rp = kp[AIBA]0.42[DMHB]0.45 and the apparent activation energy (Ea) was 83.42 kJ/mol. The particle size, ζ potential, and apparent charge density of cationic latices were also measured. The average diameter of copolymer particles decreased with increasing DMHB, MATMAC, and AIBA content; the charge properties of the particles were decided by the DMHB, MATMAC, and AIBA content. The polymerization mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1111–1116, 2006
Structure and properties of organoclay/EPDM nanocomposites: Influence of ethylene contents
Authors: Ma Yong , Wu You‐Ping , Wang Yi‐Qing , Zhang Li‐Qun
Published: November 2005

Four organoclay (OC)/ethylene–propylene–diene rubber (EPDM) nanocomposites with different ethylene contents were prepared by melt blending. X‐ray diffraction spectrum (XRD) and transmission electronic microscope (TEM) photos showed that OC/EPDM nanocomposites were intercalated, and the ethylene content had little influence on the dispersion of OC. The addition of OC prolonged the optimum cure time and reduced the crosslink density of OC/EPDM. The improvement in tensile strength of OC/EPDM nanocomposites with high ethylene contents (67–70%) was larger than that of OC/EPDM nanocomposites with low ethylene contents (52–52.5%). XRD results of the stretched samples testified that the extension promoted orientation of silicate layers, and induced crystallization of polyethylene (PE) segments in OC/EPDM nanocomposites with high ethylene contents. The highly oriented micro‐fibrillar structure and more oriented amorphous chains, which resulted from strain‐induced crystallization of PE segments and the orientation of clay layers in OC/EPDM nanocomposites with high ethylene contents (67–70%), should be responsible for larger improvement in tensile strength than that of those nanocomposites with low ethylene contents (52–52.5%) © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 914–919, 2006
Polybenzoxazine containing polysilsesquioxane: Preparation and thermal properties
Authors: Liu Yonghong , Zhang Weian , Chen Yan , Zheng Sixun
Published: November 2005

Benzoxazine bearing trimethoxylsilane (BA‐b) was successfully synthesized via Mannich condensation among phenol, paraformaldehyde, and γ‐aminopropyltrimethoxysilane. The hydrolysis and condensation of the BA‐b catalyzed by hydrochloric acid can afford a soluble polysilsesquioxane bearing benzoxazine groups (denoted PSSQ‐b). By initiating the cocuring reaction of PSSQ‐b with difunctional benzoxazine of bisphenol A (BA‐a), the inorganic–organic hybrids of polybenzoxazine with polysilsesquioxane were prepared. The hybrids displayed enhanced Tg's in comparison with the control polybenzoxazine. In terms of initial decomposition temperature (Td) and char and ceramic yields, the hybrids exhibited improved thermal stability as shown by thermogravimetric analysis (TGA). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 927–936, 2006
Time dependences of conduction and self‐heating in acetylene carbon black‐filled high‐density polyethylene composites
Authors: Song Yihu , Zheng Qiang
Published: November 2005

The time dependences of electrical conduction and self‐heating behaviors in high‐density polyethylene filled with acetylene carbon black of 0.082 in volume fraction are studied in relation to voltage and ambient temperature. The characteristic decay current constant τi, and the exponential growth time constant for self‐heating τg are determined for the samples under voltages U above the critical value Uc for the onset of self‐heating. The influences of voltage and ambient temperature on τi and τg as well as the amplitude of the low‐resistance to high‐resistance switching are discussed on the basis of the random resistor network (RRN) model and the relationship between Uc and the intrinsic resistivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1124–1131, 2006
Evaluating the thermal stability of high performance fibers by TGA
Authors: Liu Xiaoyan , Yu Weidong
Published: November 2005

The thermal degradation of eight types of high performance fibers (HPFs) was measured under nitrogen and air atmosphere. The degree of degradation, as measured by weight loss using thermogravimetric analysis (TGA), and the characteristic degradation temperatures were obtained. The kinetics of the thermal degradation has also been analyzed according to the Freeman–carroll method and the activation energies of the HPFs were estimated. The experimental results show that para‐aramids (Kevlar® 29, 49, 129, and Twaron®2000) have similar thermal stability, but their thermal degradation temperatures and activation energies in air are different from those in nitrogen, which means that the thermostability of the fiber depends not only on its intrinsic structure but also on the atmosphere and temperature of testing environment. Terlon® fiber shows higher degradation temperature as a copolymer of para‐aramid, and its initial degradation temperature is 476.4°C in air. It can also be found that the PBO (poly(p‐phenylene benzobisoxazole)) fiber has the highest thermal degradation temperature among the samples tested, but its activation energy is not the highest in both air and nitrogen atmosphere. And the UHMW‐PE (ultra high molecular weight polyethylene) fiber has the lowest thermal degradation temperature, and it begins to degrade when the temperature reaches 321.8°C under air atmosphere. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 937–944, 2006
Effects of N‐trimethyl chitosan chloride as an absorption enhancer on properties of insulin liquid suppository in vitro and in vivo
Authors: He Wen , Du Yumin , Dai Wenbing , Wu Yan , Zhang Mian
Published: November 2005

N‐trimethyl chitosan chloride (TMC), with degree of quaternization (DQ) of 42.77% (TMC40) and 63.03% (TMC60), respectively, were synthesized and used as absorption enhancers in an insulin rectal liquid suppository from poloxamers. The effects of the TMCs on the liquid suppository were investigated. Compared with sodium salicylate (10%), which increased the gelation temperature and decreased the gel strength and bioadhensive force of the liquid suppository, both TMCs increased the three indices due to hydrogen bonding between the amino groups of TMCs and hydroxyl groups of poloxamers. The higher the concentration of TMCs was, the higher the three indices were. At the same concentration, the enhancing effect of TMC60 was higher than that of TMC40. Compared with those of 10% sodium salicylate, the enhancing effects of TMC40 with concentrations of 0.05% and 0.10% and TMC60 with concentration of 0.05% were weaker, while the other testing concentrations all showed better absorption enhancing ability with lower plasma glucose levels, AUC0–4 h (the area below basal glucose level) and Cnadir (the plasma glucose levels at the nadir). Histological assessment was performed by observing irritation of the liquid suppository on the rectal tissues and observation rate of three types of gland changes in the rectal epithelium. Compared with the control (75.48 ± 16.76), TMC40 and TMC60 exhibited little change in observation rates of normal gland (72.10 ± 10.24 and 71.93 ± 9.88, respectively), while sodium salicylate showed significant lower observation rates of normal gland (51.28 ± 13.44). The insulin rectal liquid suppository with TMCs is more effective and safer than that with sodium salicylate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1140–1146, 2006
Synthesis and self‐assembly of hyperbranched polyethers peripherally modified with adenosine 5′‐monophosphate
Authors: Jiang Guohua , Wang Li , Dong Xiaochen , Chen Chang , Chen Tao
Published: November 2005

The chloride functionalized hyperbranched poly(3‐ethyl‐3‐oxetanemethanol) (HBPO) was prepared via reaction of thionyl chloride with hydroxyl groups. Adenosine 5′‐monophosphate (AMP) groups were attached to HBPO in CH2Cl2 in the presence of triethylamine (TEA) as an acceptor of HCl. The self‐assembly of resultant hyperbranched molecules bearing self‐complementary hydrogen‐bonding patterns would allow the generation of a highly organized supramolecular architecture in a selected solvent. The morphologies of self‐assembly structures were depended on the level of AMP in polymer and the concentration in solvent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1147–1152, 2006
Bioactive composites with designed interphases based on hyperbranched macromers
Authors: Oréfice Rodrigo L. , Clark Arthur E. , Brennan Anthony. B.
Published: November 2005

A series of designed interphases was produced by grafting chemically modified poly (aryl ether sulfones) (PSF) onto bioactive glass (BAG) particles. Macromolecular architecture, polymer morphology, composition and crosslink density of these PSF hybrid interphases were studied with respect to influence on mechanical properties. The hybrid PSF interphases improved mechanical strength by 20% over conventional silane treatments and increased the overall energy to failure by nearly 100%. The structure of the interphase was modeled with a three‐phase viscoelastic model. The results demonstrated the ability to engineer an interphase having hyperstructures containing mobile species and inorganic functionalities that improve adhesion and favor energy release during fracture processes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1153–1166, 2006