We have previously demonstrated that polymer plugs with sub-micron pores can suppress unwanted pressuredriven flow and enhance electro-osmotic flow in a microchannel. This paper presents two separate concepts related to electrode placement and biasing strategy that further abate generation of bubbles in the main flow. In the first concept the drive signal is applied to a main EOF porous plug through high flow resistance porous bridges present outside the main flow. In the second approach, metal electrodes are located within the main channel across a series of dielechically isolated narrow channels. Bubble generation is suppressed with a high-frequency square wave drive, and net unidirectional flow is achieved by modulation of the zeta potential on the narrow channel surfaces. Flow velocities of 10-66 p d s e c in 20-pm high channels have been achieved by these !NO methods.
Pervaporation, which is a non-pressure driven membrane process, was evaluated to determine its viability for desalinating high-salinity source waters like those originating from oil and natural gas development (produced water). Two types of membrane material chemistries were studied in order to identify the optimal properties for maximizing the permeate flux under a given set of operating conditions. Permeate flux was determined to be a significant function of membrane thickness and the diffusion coefficient of water through the membrane. The diffusion coefficient is in turn a function of the membrane's affinity for water (hydrophilicity) and its fractional free volume space. however, co-ions were able to penetrate into the membrane material matrix over time.
Effects of finite spatial size of boson assemblies in traps are studied in a self-consistent lattice theory by modeling the trap as a bounded harmonic potential of size R0. The thermodynamic quantities exhibit scaling and crossover from ideal gas behaviour at small (R0/a0) to that appropriate to an unbounded harmonic potential at large (R0/a0) with a crossover parameter [Formula: see text], a0 being the harmonic oscillator length, and τ denoting the dimensionless thermal energy. The numerical results obtained earlier by computing the energy levels of the bounded harmonic oscillator fit the general structure predicted by the theory very well. For a1>10, the spatial size effects are negligible but for a1<10 they become appreciable and experimentally measurable in suitably designed traps. At low temperatures the self consistent cell size is found to be about 2.5a0 implying that the condensate is essentially a single coherent state contained in the central cell.
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