Practice report: the role of environmental factors in industrial site selection activities: a case of limestone quarry expansion in Barbados, West Indies

Site selection is a key activity for quarry expansion to support cement production, and is governed by factors such as resource availability, logistics, costs, and socio-environmental factors. Adequate consideration of all factors facilitates both industrial productivity and sustainable economic growth. This study illustrates the site selection process that was undertaken for the expansion of limestone quarry operations to support cement production in Barbados. First, alternate sites with adequate resources to support a 25-year development horizon were identified. Second, socio-environmental conditions were described and potential impacts identified. Third, a comparative matrix was constructed to evaluate relative site characteristics with respect to physical, ecological, socio-cultural and economic factors. The study shows that environmental factors were essential to the final site recommendation.

The effect of blending on selected physical properties of crude oils and their products

A study was made of the effect of blending practice upon selected physical properties of crude oils, and of various base oils and petroleum products, using a range of binary mixtures. The crudes comprised light, medium and heavy Kuwait crude oils. The properties included kinematic viscosity, pour point, boiling point and Reid vapour pressure. The literature related to the prediction of these properties, and the changes reported to occur on blending, was critically reviewed as a preliminary to the study. The kinematic viscosity of petroleum oils in general exhibited non-ideal behaviour upon blending. A mechanism was proposed for this behaviour which took into account the effect of asphaltenes content. A correlation was developed, as a modification of Grunberg's equation, to predict the viscosities of binary mixtures of petroleum oils. A correlation was also developed to predict the viscosities of ternary mixtures. This correlation showed better agreement with experimental data (< 6% deviation for crude oils and 2.0% for base oils) than currently-used methods, i.e. ASTM and Refutas methods. An investigation was made of the effect of temperature on the viscosities of crude oils and petroleum products at atmospheric pressure. The effect of pressure on the viscosity of crude oil was also studied. A correlation was developed to predict the viscosity at high pressures (up to 8000 psi), which gave significantly better agreement with the experimental data than the current method due to Kouzel (5.2% and 6.0% deviation for the binary and ternary mixtures respectively). Eyring's theory of viscous flow was critically investigated, and a modification was proposed which extends its application to petroleum oils. The effect of blending on the pour points of selected petroleum oils was studied together with the effect of wax formation and asphaltenes content. Depression of the pour point was always obtained with crude oil binary mixtures. A mechanism was proposed to explain the pour point behaviour of the different binary mixtures. The effects of blending on the boiling point ranges and Reid vapour pressures of binary mixtures of petroleum oils were investigated. The boiling point range exhibited ideal behaviour but the R.V.P. showed negative deviations from it in all cases. Molecular weights of these mixtures were ideal, but the densities and molar volumes were not. The stability of the various crude oil binary mixtures, in terms of viscosity, was studied over a temperature range of 1oC - 30oC for up to 12 weeks. Good stability was found in most cases.

Type 2 diabetes and dog walking:patients' longitudinal perspectives about implementing and sustaining physical activity

Background - Physical activity is particularly important for people with type 2 diabetes, as evidence suggests that any reduction in sedentary time is good for metabolic health. Aim - To explore type 2 diabetes patients' talk about implementing and sustaining physical activity. Design of study - Longitudinal, qualitative study using repeat in-depth interviews with 20 patients over 4 years following clinical diagnosis. Setting - Patients were recruited from 16 general practices and three hospitals across Lothian, Scotland. Results - Discussion, and salience, of physical activity was marginal in patient accounts of their diabetes management. Patients claimed to have only received vague and non-specific guidance about physical activity from health professionals, and emphasised a perceived lack of interest and encouragement. Aside from walking, physical activities which were adopted tended to attenuate over time. Patients' accounts revealed how walking a dog assisted this kind of activity maintenance over time. Three main themes are highlighted in the analysis: 1) incidental walking; 2) incremental physical activity gains; and 3) augmenting physical activity maintenance. The problems arising from walking without a dog (for example, lack of motivation) are also examined. Conclusion - Asking patients about pet preferences might seem tangential to medical interactions. However, encouraging dog walking or identifying another interest that promotes a regular commitment to undertake physical activity may yield long-term health benefits.