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This work investigates the recovery of a deep eutectic solvent (DES) used for pulping wood, by removing remnant hemicellulosic derivatives using reverse osmosis (RO). Xylose and its dehydration product furfural are considered representative hemicellulosic derivatives, and a lactic acid-choline chloride DES was used. Various diluting solvents were considered for the RO feed, namely pure water and binary water-organic solvent (ethanol, acetone, and methanol) mixtures. The results in this work show that the xylose rejection is high in water as well as in the presence of organic solvents such as acetone (with 97% rejection in aqueous acetone solvent and 95% in pure water using the RO membrane). On the other hand, furfural is rejected poorly by the RO membrane in all media (below 60% in all solvents). Finally, based on these results, a separation scheme was proposed to attain a complete mass recovery of each component of this mixture.

The preferential removal of sodium sulfate over sodium chloride (fractionation) by nanofiltration (NF) is studied. A fractionation metric, M, is defined, and a simple set of equations are derived to describe its variation due to operating parameters, such as temperature and pressure. The use of these equations to explain known behavior of NF systems and suggest improvements in system or membrane design is demonstrated. Furthermore, the derived framework is applicable to all membranes used in pressure-driven technologies, without detailed characterization of specific membrane properties, such as structural parameters (pore radius, active layer thickness, tortuosity, porosity) or charge-based parameters. Given that the principal applications of NF involve the selective removal of multivalent ions over monovalent ions, the introduced metric provides a direct measure of its efficacy in such applications, and is shown to be more accurate in some cases than comparing salt rejection ratios, as usually done. Finally, the concept of ‘breakthrough’, commonly observed as the point at which rejection ratio begins to decrease with increase in pressure, is mathematically described, and its implication on selectivity discussed.

The present work demonstrates that experimental salt passage data for reverse osmosis (RO) shows better agreement with models capturing solute-solvent transport coupling (convective coupling), especially as the applied pressure is increased. This conclusion is drawn based on five RO data sets using cellulose acetate and polyamide membranes that were modeled using the classical solution diffusion (SD) model, which does not include convection, as well as the convection-inclusive SD model introduced by Paul in 2004 and the pore-based model, which also includes convective coupling. The improved model-to-experimental data agreement with solute-solvent coupling is more easily noticed from salt passage variation with pressure than from the most commonly studied RO metric, salt rejection ratio. The importance of solute-solvent coupling in RO indicates that free volume in the membrane influences the description of membrane transport, and that these voids *open up as applied pressure is increased. The derivation of the pore-based and SD models from the Maxwell-Stefan equations is shown, and major differences in assumptions used in their derivation are discussed. A study of these differences should aid membrane researchers in selecting the most appropriate modeling approach for a given solute-solvent-membrane system.

Cilia are hair-like organelles projecting from a eukaryotic cell, used either for locomotion or as sensors. Cilia commonly occur in patches. To take this into consideration, we represent cilia in multiple patches, instead of the conventional 'dense mat' representation. We focus on the combined action and interplay of these patches. The effects of varying the frequency, spacing and phase lag of the beating of one cilia bunch with respect to the beating of adjacent patches are studied. We model the Airway Surface Liquid (ASL) as a three-layer structure. The possibility of an optimum frequency of beating is noted and the change of mucous flow under different spacing and phase differences are observed. � 2013 Elsevier Ltd.

Erratum to “Effect of bunching of cilia and their interplay on muco-ciliary transport” [Comput. Biol. Med. 43 (2013) 1758–1772] Yagnaseni Roy , Vivek Sivathanu , Sarit K. Das c,n a Department of Mechanical Engineering, SRM University, Chennai 603203, India b Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA c HTTP Lab, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 603203, India