Museo Shah-Dany: Packaging the Past to Promote the Future

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Novel nanomaterials for water desalination technology

Water desalination has a central role to play in the global challenge for sustainable water supply in the 21st century. But while the membranes employed in reverse osmosis (RO) have benefited from substantial improvements over the past 25 years, several recent advances in materials suggest that new membranes with dramatically higher water permeability will become available in the future. After providing an overview of the importance of membranes for sustainable water production, we describe some of the most exciting novel approaches for water desalination based on nanomaterials. In particular, graphene, a single-layer sheet of carbon with remarkable mechanical and electronic properties, can be patterned with nanometer-sized pores, to act as an ultra-thin filtration membrane. Drawing from our group's research at MIT, we will share some of our key findings about the potential impact of nanomaterials as membranes for water desalination in the 21st century.MIT Energy InitiativeNational Science Foundation (U.S.)MIT Energy Initiative. Seed Fund ProgramJohn S. Hennessy Fellowshi

Quantifying the potential of ultra-permeable membranes for water desalination

In the face of growing water scarcity, it is critical to understand the potential of saltwater desalination as a long-term water supply option. Recent studies have highlighted the promise of new membrane materials that could desalinate water while exhibiting far greater permeability than conventional reverse osmosis (RO) membranes, but the question remains whether higher permeability can translate into significant reductions in the cost of desalinating water. Here, we address a critical question by evaluating the potential of such ultra-permeable membranes (UPMs) to improve the performance and cost of RO. By modeling the mass transport inside RO pressure vessels, we quantify how much a tripling in the water permeability of a membrane would reduce the energy consumption or the number of required pressure vessels for a given RO plant. We find that a tripling in permeability would allow for 44% fewer pressure vessels or 15% less energy for a seawater RO plant with a given capacity and recovery ratio. Moreover, a tripling in permeability would result in 63% fewer pressure vessels or 46% less energy for brackish water RO. However, we also find that the energy savings of UPMs exhibit a law of diminishing returns due to thermodynamics and concentration polarization at the membrane surface.National Science Foundation (U.S.). Graduate Research FellowshipMIT Energy Initiative (Seed Grant Program)Fulbright Program (International Science and Technology Award Program)International Desalination Association (Channabasappa Memorial Scholarship)Martin Family Fellowship for Sustainabilit

Age and Body Satisfaction Predict Diet Adherence in Adolescents with Inflammatory Bowel Disease

The aim of the current study was to determine whether age and body satisfaction predict dietary adherence in adolescents with Inflammatory Bowel Disease (IBD), and whether older females are less adherent than younger males and females. Forty-four participants aged 10-21 with IBD were recruited. Participants provided informed consent and demographics. Body satisfaction was measured by a questionnaire and a task in which participants selected their current and ideal body image out of silhouettes depicting bodies ranging from underweight to obese. Adherence was measured by marking a 100mm visual analog scale, the 1-week completion of a dietary log, and a questionnaire evaluating coping strategies used for overcoming obstacles to dietary adherence. Age was related to dietary adherence, with younger children being more likely to adhere. Participants more satisfied with their body reported better dietary adherence. Findings remained consistent across multiple measures of body satisfaction and adherence. Healthcare providers and parents should be informed of these findings in order to improve adherence

Flat branches and pressure amorphization

After summarizing the phenomenology of pressure amorphization (PA), we present a theory of PA based on the notion that one or more branches of the phonon spectrum soften and flatten with increasing pressure. The theory expresses the anharmonic dynamics of the flat branches in terms of local modes, represented by lattice Wannier functions, which are in turn used to construct an effective Hamiltonian. When the low-pressure structure becomes metastable with respect to the high-pressure equilibrium phase and the relevant branches are sufficiently flat, transformation into an amorphous phase is shown to be kinetically favored because of the exponentially large number of both amorphous phases and reaction pathways. In effect, the critical-size nucleus for the first-order phase transition is found to be reduced to a single unit cell, or nearly so. Random nucleation into symmetrically equivalent local configurations characteristic of the high-pressure structure is then shown to overwhelm any possible domain growth, and an ``amorphous'' structure results.Comment: 8 pages with 3 postscript figures embedded; Proceedings of the 4th International Discussion Meeting on Relaxations in Complex Systems, Hersonissos, Heraklion, Crete, June 16-23, ed. K. L. Ngai, Special Issues of the Journal of Non-Crystalline Solids, 200