No abstract

Limited availability of natural resources and rising raw material cost, accompanied by growing societal and environmental concerns, urge the engineers to incorporate sustainability issues into the design of new chemical process and the retrofit of traditional process. Yet due to the multidimensional nature of sustainability, as economic, societal, and environmental issues need to be considered together, a structured sustainability assessment tool is needed to serve as the basis for any process design, analysis, improvement, and decision making. This paper presents a methodology to assist reaction pathway selection in light of sustainability. At this conceptual design stage, the sustainability performance of different potential reaction pathways is evaluated, which can not only help the designers improve the screening efficiency by eliminating inferior reaction alternatives systematically, but also identify the key areas for further improvement in future design, thus reducing the complexity and labor in the following basic engineering design stage. The sustainability of each reaction pathway is assessed in terms of profit potential, driving force of the pathway (Gibbs free energy), inherent safety index, potential environmental index, and atom economy. The efficacy of this approach is demonstrated by several case studies of reaction routes selection, including the propylene oxide (PO) production process, carbon dioxide reduction technology, and cellulosic ethanol production technology.

ObjectivesTo evaluate whether four types of low-cost interventions in the working environment can promote the small everyday lifestyle adaptations that can halt the epidemics of obesity and hypertension when maintained long term.DesignA single-blind uninterrupted time-series intervention study consisting of four study periods: run-in (2 weeks), baseline (2 weeks), intervention (2 weeks), and after intervention 2 weeks).SettingUniversity Medical Centre with over 11 000 employees, over 1000 hospital beds and over 2000 customers visiting the hospital restaurant each day.ParticipantsHospital staff and visitors.Interventions(1) Point-of-decision prompts on hospital elevator doors promoting stair use. (2) Point-of-purchase prompts in the hospital restaurant promoting reduced-salt soup. (3) Point-of-purchase prompts in the hospital restaurant promoting lean croissants. (4) Reversal of the accessibility and availability of diet margarine and butter in the hospital restaurant.Main outcome measures(1) Number of passages through 15 different parts of the hospital staircases. (2) Number and ratio of normal-salt and reduced-salt soup purchased. (3) Number and ratio of butter croissants and lean croissants purchased. (4) Number and ratio of diet margarine and butter purchased.ResultsElevator signs increased the mean 24-h number of stair passages per measurement site (baseline: 992 ± 479 on week days and 208 ± 116 on weekend days) by 11.2% (95% CI 8.7% to 13.7%). This effect was maintained at least 2 weeks after the point-of-decision prompts were removed. Point-of-purchase prompts promoting low-salt soup and lean croissants did not result in altered purchase behaviour. The ratio between the purchase of margarine and butter was changed sevenfold (p<0.01) by reversing the positions of these products in the hospital restaurant.ConclusionsHealthy lifestyle adaptations in the working environment can be effectively promoted by making healthy choices easier than unhealthy ones. Educational prompts at points-of-decision moderately increase stair climbing, but do not affect healthy food choices.Protocol registrationClinicaltrials.gov identifier number: NCT01574040.

No abstract

Most investigations on heat exchanger network (HEN) synthesis which plays an important role in improving the efficiency of industrial plants, focus on deterministic conditions whereas operational flexibility and feasibility are less concerned. In the real industrial world, each system experiences various disturbances due to changes in stream temperature, flow rate, and other uncertain factors. An approach for flexible HEN synthesis under severe operation uncertainty is proposed, which is represented by the Probability bounds analysis (PBA) theory and is sampled by a double-loop sampling method. A case study, which generates a better solution with less total annual cost and good flexibility under severe uncertainty, demonstrates the capability of this simplified approach.