Atomistic Study of Dynamic Contact Angles in CO2-Water-Silica System.

The dynamic wetting for the CO2-water-silica system occurring in deep reservoirs is complex because of the interactions among multiple phases. This work aims to quantify the contact angle of CO2-water flow in the silica channel at six different flow velocities using molecular dynamics. The dynamic contact angle values at different contact line velocities are obtained for the CO2-water-silica system. By calculating the rates of the adsorption-desorption process of CO2 and water molecules on the silica surface using molecular dynamics simulations, it has been found that the results of the dynamic contact angle can be explained by the molecular kinetic theory and predicted from the equilibrium molecular simulations. Moreover, the capillary pressure at different contact line velocities is predicted according to the Young-Laplace equation. The change in contact angles at different velocities is compared with empirical equations in terms of capillary number. The results of this study can help us better understand the dynamic process of the multiphase flow at the nanoscale under realistic reservoir conditions.

Coarse-grained modeling of multiphase interactions at microscale.

The objective of this study is to develop and test a coarse-grained molecular dynamics framework to model microscale multiphase systems with different inter-particle interactions and recover emerging thermodynamic and mechanical properties at the microscale. A water-vapor model and a fused silica model are developed to demonstrate the capability of our framework. The former can reproduce the water density and surface tension over a wide range of temperatures; the latter can reproduce experimental density, tensile strength, and Young's modulus of fused silica. Therefore, the deformable solid model is implemented in the proposed framework. Validations of spatial scaling methods for solid, liquid, and multiphase systems suggest that the proposed framework can be calibrated at an arbitrary microscale and used at a different length scale without recalibration. Different values of wettability for a solid-liquid-vapor system that is characterized by the contact angle can be achieved by changing the solid-liquid inter-particle potential. Thanks to these features, the proposed coarse-grained molecular dynamics framework can potentially find applications in modeling systems in which multiple phases coexist and have substantial interactions.

Health and ecological sustainability in the Arab world: a matter of survival.

Discussions leading to the Rio+20 UN conference have emphasised the importance of sustainable development and the protection of the environment for future generations. The Arab world faces large-scale threats to its sustainable development and, most of all, to the viability and existence of the ecological systems for its human settlements. The dynamics of population change, ecological degradation, and resource scarcity, and development policies and practices, all occurring in complex and highly unstable geopolitical and economic environments, are fostering the poor prospects. In this report, we discuss the most pertinent population-environment-development dynamics in the Arab world, and the two-way interactions between these dynamics and health, on the basis of current data. We draw attention to trends that are relevant to health professionals and researchers, but emphasise that the dynamics generating these trends have implications that go well beyond health. We argue that the current discourse on health, population, and development in the Arab world has largely failed to convey a sense of urgency, when the survival of whole communities is at stake. The dismal ecological and development records of Arab countries over the past two decades call for new directions. We suggest that regional ecological integration around exchange of water, energy, food, and labour, though politically difficult to achieve, offers the best hope to improve the adaptive capacity of individual Arab nations. The transformative political changes taking place in the Arab world offer promise, indeed an imperative, for such renewal. We call on policy makers, researchers, practitioners, and international agencies to emphasise the urgency and take action.

A review of rural and peri-urban sanitation infrastructure in South-East Asia and the Western Pacific: Highlighting regional inequalities and limited data.

Rural and peri-urban communities in developing countries rely on sanitation systems which are often unsafely managed. One of the major barriers to assess safely managed sanitation is a lack of data about the existing sanitation infrastructure and levels of containment safety. The aim was to review rural and peri-urban on-site sanitation studies in order to understand different infrastructure types, associated management practices and any impacts on human health. The scope was limited to South-East Asia and Western Pacific regions in order to better identify regional inequalities. Among the 155 reviewed articles, 73 studies (47%) linked sanitation infrastructure to poor human health. Nearly all articles reported latrine ownership (n = 149, 96%) while sanitation infrastructure types were covered less frequently (n = 104, 67%). In particular, there was a lack of published literature describing back-end characteristics (dimension and materials) (n = 12, 8%) and/or management practices (n = 4, 3%). This stems from a limited application of research methodologies that characterise sanitation infrastructure and faecal sludge management (containment, emptying and on-site treatment). Inequality between regions was prevalent with three quarters of the studies on latrine back-end infrastructure from Bangladesh and India in South-East Asia. A strategic research approach is needed to address the current knowledge gaps regarding sanitation infrastructure and safe faecal sludge management.

Strategies for the municipal waste management system to take advantage of carbon trading under competing policies: The role of energy from waste in Sydney.

Climate change is a driving force behind some recent environmental legislation around the world. Greenhouse gas emission reduction targets have been set in many industrialised countries. A change in current practices of almost all greenhouse-emitting industrial sectors is unavoidable, if the set targets is to be achieved. Although, waste disposal contributes around 3% of the total greenhouse gas emissions in Australia (mainly due to fugitive methane emissions from landfills), the carbon credit and trading scheme set to start in 2010 presents significant challenges and opportunities to municipal solid waste practitioners. Technological advances in waste management, if adopted properly, allow the municipal solid waste sector to act as carbon sink, hence earning tradable carbon credits. However, due to the complexity of the system and its inherent uncertainties, optimizing it for carbon credits may worsen its performance under other criteria. We use an integrated, stochastic multi-criteria decision-making tool that we developed earlier to analyse the carbon credit potential of Sydney municipal solid waste under eleven possible future strategies. We find that the changing legislative environment is likely to make current practices highly non-optimal and increase pressures for a change of waste management strategy.

Did a ban on diesel-fuel reduce emergency respiratory admissions for children?

This paper assesses whether a ban on diesel-powered motor vehicles in Lebanon has reduced emergency respiratory admissions for children less than 17 years of age in Beirut. Monthly admissions for total respiratory complaints, asthma, bronchitis, pneumonia, and upper respiratory tract infections, from October to February, were compared before and after the ban, using Poisson regression models and adjusting for rainfall, humidity and temperature. Analyses were repeated excluding the flu months of January and February. A test of significance of p < or = 0.05 was used. Air pollution is not systematically monitored in Lebanon and no ambient particulate concentration data were available. A significant drop in admissions for respiratory symptoms (p < or = 0.05) and upper respiratory tract infection (p < or = 0.001) from 1 year pre-ban to 1 year post-ban has been recorded. When flu months are excluded, a significant drop (p < or = 0.001) in admissions for all studied categories, except pneumonia, is observed. The effect of the ban however was negligible in the second year. When 2 year pre-ban versus 2 year post-ban are considered excluding flu months, statistically non-significant reductions are recorded for asthma and upper respiratory tract infection (p < or = 0.1). The study hence suggests an impact of the diesel ban on respiratory health only during the first year after the ban. This finding is weakened by the absence of supporting evidence from air quality monitoring and speciation of particulate matter, which are lacking in Lebanon and most developing countries.

On the association between high temperature and mortality in warm climates.

We conducted a time-series analysis of 1997-1999 data records of air temperature and all-cause mortality in Greater Beirut, using bi-linear Poisson auto-regressive models, and published our findings in the Science of the Total Environment [El-Zein, A., Tewtel-Salem, M., Nehme, G., 2004. A time-series analysis of mortality and air temperature in Greater Beirut. Sci. Total Environ. 330, 71-80]. We compared our results to those of Curriero et al. [Curriero, F.C., Heiner, K.S., Samet, J.M., Zeger, S.L., Strug, L., Patz, J.A., 2002. Temperature and mortality in 11 cities of the Eastern United States. Am. J. Epidemiol. 155(1) 80-87.], who subsequently reported that their original results were inaccurate and published new results [Curriero, F.C., Heiner, K.S., Samet, J.M., Zeger, S.L., Strug, L., Patz, J.A., 2002. Temperature and mortality in 11 cities of the Eastern United States. Am. J. Epidemiol. 155(1) 80-87; Curriero, F.C., Samet, J.M., Zeger, S.L., 2003. Letter to the Editor re. On the Use of Generalized Additive Models in Time-Series Studies of Air Pollution and Health" and "Temperature and Mortality in 11 Cities of the Eastern United States". Am. J. Epidemiol. 158(1) 93-94.]. In this letter, we report two changes in the interpretation of our findings as a result of the change in the results of Curriero et al. [Curriero, F.C., Heiner, K.S., Samet, J.M., Zeger, S.L., Strug, L., Patz, J.A., 2002. Temperature and mortality in 11 cities of the Eastern United States. Am. J. Epidemiol. 155(1) 80-87]. Their newly-reported results reinforce our conclusion that heat-related mortality can be a significant public health issue even in temperate to warm climates. However, our findings raise a question concerning the ability of socioeconomic indicators to explain differences in vulnerability to heat between high-income and low-income countries.

A time-series analysis of mortality and air temperature in Greater Beirut.

The literature on the association between health and weather in the temperate to semi-arid cities of the Eastern Mediterranean is scarce. The quantification of the relationship between temperature and daily mortality can be useful for developing policy interventions such as heat-warning systems. A time-series analysis of total daily mortality and weather data for the city of Beirut was carried out. The study covered the period between 1997 and 1999. Poisson auto-regressive models were constructed, with mean daily temperature and mean daily humidity as explanatory variables. Delayed effects, up to 2 weeks, were accounted for. The regression models were used next to assess the effect of an average increase in temperature on yearly mortality. The association between temperature and mortality was found to be significant. A relatively high minimum-mortality temperature (TMM) of 27.5 degrees C was calculated. A 1 degrees C rise in temperature yielded a 12.3% increase (95% confidence interval: 5.7-19.4%) and 2.9% decrease (95% confidence interval: 2-3.7%) in mortality, above and below TMM, respectively. Lag temperature variables were found to be significant below TMM but not above it. Where the temperature change was less than 0.5 degrees C, annual above-TMM losses were offset by below-TMM gains, within a 95% confidence interval. TMM for Beirut fell within the range usually associated with warm climates. However, the mild below-TMM and steep above-TMM slopes were more typical of cities with temperate to cold climates. Our findings suggest that heat-related mortality at moderately high temperatures can be a significant public health issue in countries with warm climates. Moreover, at the projected climate change over the next 50 years, heat-related losses are unlikely to be offset by cold-related gains.

Life-cycle assessment of municipal solid waste management alternatives with consideration of uncertainty: SIWMS development and application.

This paper describes the development and application of the Stochastic Integrated Waste Management Simulator (SIWMS) model. SIWMS provides a detailed view of the environmental impacts and associated costs of municipal solid waste (MSW) management alternatives under conditions of uncertainty. The model follows a life-cycle inventory approach extended with compensatory systems to provide more equitable bases for comparing different alternatives. Economic performance is measured by the net present value. The model is verified against four publicly available models under deterministic conditions and then used to study the impact of uncertainty on Sydney's MSW management 'best practices'. Uncertainty has a significant effect on all impact categories. The greatest effect is observed in the global warming category where a reversal of impact direction is predicted. The reliability of the system is most sensitive to uncertainties in the waste processing and disposal. The results highlight the importance of incorporating uncertainty at all stages to better understand the behaviour of the MSW system.

The development and application of multi-criteria decision-making tool with consideration of uncertainty: the selection of a management strategy for the bio-degradable fraction in the municipal solid waste.

A modified version of the multi-criteria decision aid, ELECTRE III has been developed to account for uncertainty in criteria weightings and threshold values. The new procedure, called ELECTRE-SS, modifies the exploitation phase in ELECTRE III, through a new definition of the pre-order and the introduction of a ranking index (RI). The new approach accommodates cases where incomplete or uncertain preference data are present. The method is applied to a case of selecting a management strategy for the bio-degradable fraction in the municipal solid waste of Sydney. Ten alternatives are compared against 11 criteria. The results show that anaerobic digestion (AD) and composting of paper are less environmentally sound options than recycling. AD is likely to out-perform incineration where a market for heating does not exist. Moreover, landfilling can be a sound alternative, when considering overall performance and conditions of uncertainty.

Determinants of the willingness-to-participate in an environmental intervention in a beirut neighborhood.

Participatory environmental management can empower communities and enhance the sustainability of environmental interventions. However, existing power structures and inequalities along class, gender, or ethnic lines could prevent part of the community from accessing the full benefits of the intervention. An analysis of determinants of the willingness-to-participate in an environmental intervention in a Beirut neighborhood is conducted. Socioeconomic, health-risk distribution, and perception of community efficacy are used as predictors. A randomly selected sample of residents was surveyed. Respondents were asked to specify the frequency with which they were willing to be involved in an intervention to address priority environmental problems in the neighborhood. Bivariate and multivariate ordinal regression analyses were conducted. Tests of significance were based on the 95% confidence intervals (CI) of the odds ratio (OR). Males versus females (OR = 4.89, P < 0.001), respiratory patients versus nonsufferers (OR = 5.65, P < 0.001), tenants versus house owners (OR = 2.98, P < 0.01), and the less educated versus the more educated (OR = 2.42, P < 0.05) were significantly more likely to be willing to participate. The reluctance of female community members to participate might be a major hindrance to community-based environmental protection and special strategies must be devised to overcome it. On the other hand, respondents suffering from an illness perceived to be related to environmental toxins are likely to be strong participants in environmental conservation efforts. Finally, the study yielded no evidence that belief or lack of it in the efficacy of community action is a good predictor of the willingness-to-participate in such action.

Why do neighbors have different environmental priorities? Analysis of environmental risk perception in a Beirut neighborhood.

Differences in environmental priorities within an urban neighborhood of Beirut are analyzed. The explanatory capabilities of five categories of contextual variables are compared: socioeconomic status, locality, health, behavior, and environmental beliefs. Semi-structured interviews with key individuals in the community and residents were first conducted. Four environmental issues of concern were identified. A survey was carried out to identify the relative priority accorded by respondents to these four issues, and to measure variables likely to explain differences of opinion. Bivariate and multivariate logistic regression analyses were conducted for each of the four problems. The 99% confidence interval (CI) of the odds ratio (OR) was used as a test of significance. Respondents suffering from a respiratory disease (OR = 6.94, 99%CI = 1.54-31.25), those living in less crowded houses (OR = 4.88, 99%CI = 1.38-17.24), and those not living close to the neighborhood's industrial street (OR=5.26, 99%CI = 1.01-27.78) are significantly more likely to rank poor air quality first. Significant associations are found between poor water quality as first priority and nonpresence of a smoker in the household (OR = 6.12, 99%CI = 1.84-20.32) and perception of water salinity as a problem (OR = 7.46, 99%CI = 1.50-37.03). Males (OR = 6.94, 99%CI = 1.02-47.62) and tenants versus owners (OR = 10.49, 99%CI = 1.36-80.61) are significantly more likely to rank the residential-industrial mix first. Socioeconomic variables retain their explanatory capability in the studied neighborhood, despite relatively small income disparities. Behavioral variables, such as smoking, may be causative factors of priorities. Analyzing relative priorities, rather than "concern" or lack of it, reveals more complex patterns of association. Identifying environmental-perception divide lines can help develop a more inclusive and effective participatory environmental management.

Exposure of pre-school children to passive cigarette and narghile smoke in Beirut.

BACKGROUND: Narghile is a resurging smoking device. However, little research has been done to assess passive smoking exposure. The objective of the present study is to evaluate the exposure of pre-school age children in Beirut to parental passive smoking from cigarette and/or narghile. METHODS: Data were collected from 1057 pre-school age children attending 16 day cares and 7 nursery schools in the city of Beirut. RESULTS: The overall prevalence of parental smoking (cigarette and/or narghile) was 53.3%. Ten per cent of respondents reported smoking only narghile. Fathers were significantly more likely than mothers to smoke cigarettes. However, there was no significant difference between fathers and mothers with respect to smoking narghile only. Education was a significant predictor for smoking cigarettes but not for smoking narghile. CONCLUSION: Narghile smoking appears to follow different gender and social patterns than cigarette smoking. Further research is needed to establish the determinants of narghile smoking, in order to develop adequate prevention policies.