The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

In-situ sparging: Mass transfer mechanisms

In-situ sparging has been accepted as a method to rapidly remediate groundwater at considerably lower costs compared to remedies based on groundwater recovery alone. The success of in-situ sparging depends on effective mass transfer between air and contaminated media in the subsurface. Factors affecting mass transfer include advective airflow, diffusive transport, interphase chemical partitioning, and chemical and biological reaction rates between sparged gases and subsurface contaminants, minerals, and naturally occurring organic compounds. Understanding these factors can increase the design efficiency of in-situ sparging and assist in developing sparging systems that use gases other than air (i.e., oxygen, ozone, and methane).     

Review of information on pesticide residues in the Canadian environment

Summary Pesticide residues in soil, water, food, wildlife and other media have been analysed in several monitoring studies. The purpose was to establish the distribution of these residues across a defined area, ascertain their trend over a specific period and use the results to assess environmental compliance and safety. In the present review the availability of information on pesticide residues in various Canadian environmental components was sought. With the possible exception of localized pesticide contamination of some private water supply wells, ground and surface water, most analyses revealed concentrations below guideline limits. Only a few cases were reported of mishandling, misuse and poisoning from pesticides. Continuing surveillance programmes and in-depth and well-organized monitoring studies, with special focus on areas that are vulnerable to contamination, by both provincial and federal governments, are largely responsible for the encouraging results. This experience in the control of pesticide use and monitoring of residues in the environment should be of particular interest in developing countries.Dr A.Y. Sangodoyin is a senior lecturer in the Department of Agricultural Engineering at the University of Ibadan. He was recently involved in a study visit to the University of Alberta, Edmonton, Alberta, Canada T6G 2G7, where his co-author Dr D.W. Smith is a member of staff in the Department of Civil-Engineering.     

Pressures,trends, and impacts in coastal zones: Interactions between socioeconomic and natural systems

This paper assesses the status of coastal zones in the context of expected climate change and its related impacts, as well as current and future socioeconomic pressures and impacts. It is argued that external stresses and shocks relating to sea-level rise and other changes will tend to exacerbate existing environmental pressures and damage in coastal zones. Coastal zones are under increasing stress because of an interrelated set of planning failures including information, economic market, and policy intervention failures. Moves towards integrated coastal zone management are urgently required to guide the coevolution of natural and human systems. Overtly technocentric claims that assessments of vulnerability undertaken to date are overestimates of likely future damages from global warming are premature. While it is the case that forecasts of sea-level rise have been scaled down, much uncertainty remains over, for example, combined storm, sea surge, and other events. In any case, within the socioeconomic analyses of the problem, resource valuations have been at best only partial and have failed to incorporate sensitivity analysis in terms of the discount rates utilized. This would indicate an underestimation of potential damage costs. Overall, a precautionary approach is justified based on the need to act ahead of adequate information acquisition, economically efficient resource pricing and proactive coastal planning.     

Inchelium: non-sustainable resource dependency

Summary In order to consider appropriate sustainable development, it is first necessary to understand the problems of developments that are inappropriate for specific population groups. Variables, such as, the culture of the group, its historical experiences, demographic and economic resources, population density, and remoteness or urban proximity should be scrutinized. This is a case study of one population group with a history of resource dependency.Inchelium is a small Native American community on the Colville Indian Reservation in Washington, USA. The construction of a large dam ended fishing in Inchelium. Changes due to the dam have led to exploitation and degradation of the community's lifestyle. Several attempts at viable alternative economic development have led to disagreements about cultural and environmental issues. Lack of sustainable development has fostered a non-viable economy. In this economy half of the employable persons are unemployed, and 80 percent are dependent upon some form of government financial and service aid.These problems are related to the effects of colonization found on all North American Indian reservations. A dependency relationship with the federal government has resulted in qualitative changes in the use of natural resources, from subsistence to extraction.Dr Pamela Elkind is Department Chairperson and Professor of Environmental Sociology at Eastern Washington University. David Lundgren is based in the Department of Sociology at Stevenson College. This paper was first delivered at the Global Forum '94 Conference in Manchester, UK.     

Comparing EQM practices of small and large companies

There is some concern in the environmental quality management (EQM) community that small and mid-sized companies do not have the technical, economic, and personnel resources or expertise to carry out significant programs of pollution prevention or waste reduction in the way that large corporations do. Thus, a very significant proportion of the economy may not be contributing to or benefiting from EQM approaches. This article begins to clarify what small and mid-sized companies that are committed to EQM can actually do and how this compares with the efforts of larger plants or plants operated as part of large multiplant corporations.     

PESTICIDES IN GROUND WATER: DO ATRAZINE METABOLITES MATTER?1

ABSTRACT: Atrazine and atrazine-residue (atrazine + two metabolites - deethylatrazine and deisopropylatrazine) concentrations were examined to determine if consideration of these atrazine metabolites substantially adds to our understanding of the distribution of this pesticide in groundwater of the midcontinental United States. The mean of atrazine.residue concentrations was 53 percent greater than that of atrazine alone for those observations above the detection limit (> 0.05 μg/l). Furthermore, a censored regression analysis using atrazine-residue concentrations revealed significant factors not identified when only atrazine concentrations were used. Thus, knowledge of concentrations of these atrazine metabolites is required to obtain a true estimation of risk of using these aquifers as sources for drinking water, and such knowledge also provides information that ultimately may be important for future management policies designed to reduce atrazine concentrations in ground water.     

Prevention of musculoskeletal complaints in nursing: Aims, approach and content of an ergonomic-educational programme

In 1992 a comprehensive health-promotion project was initiated in seven nursing-homes in the Netherlands. This project was designed to implement an ergonomic-educational programme, with the intention of reducing physical workload and to bring about safe working in order to prevent work-related musculoskeletal complaints. After a period of external support, employees of the nursing-homes should be able to proceed with the programme independently. In this paper the content of the programme and its underlying strategies and theories are described. So far, the programme has got off to a good start in all the nursing-homes. Positive effects of the programme could be demonstrated and guidelines and protocols for safe working were introduced. However, it is as yet too early for definitive conclusions to be drawn regarding the aspect of continuity.     

Getting the ‘pulse’ of your employees: the use of cardiovascular research in better understanding behavior in organizations

Cardiovascular disease has severe consequences for both individual betterment and organizational health. Yet, organization‐based cardiovascular research remains quite limited. This commentary addresses this void by integrating research dating from the famous Hawthorne experiments with current medical science. It then suggests future organizational research on cardiovascular health and recommends use of specific composite cardiovascular measures to advance our understanding of the organizational implications of cardiovascular disease. Copyright © 2006 John Wiley & Sons, Ltd.     

Locus of control at work: a meta‐analysis

This study meta‐analyzed the relationships between locus of control (LOC) and a wide range of work outcomes. We categorized these outcomes according to three theoretical perspectives: LOC and well‐being, LOC and motivation, and LOC and behavioral orientation. Hypotheses reflecting these three perspectives were proposed and tested. It was found that internal locus was positively associated with favorable work outcomes, such as positive task and social experiences, and greater job motivation. Our findings are discussed in relation to research on core self‐evaluation and the Big Five personality traits. Copyright © 2006 John Wiley & Sons, Ltd.