Electrokinetic transport within a buffer-filled microchannel incorporating a flat bipolar electrode is investigated. The key finding is that the presence of the electrode disrupts the passage of electrical current through the microchannel and thereby alters the uniformity of the local electric field. Electroosmotic flow further modulates the local field gradient. These dynamics are demonstrated experimentally by utilizing the field gradient for concentration enrichment of negatively charged tracer molecules, and a set of computer simulations is presented to interpret the underlying electrokinetics.
The development of a new class of surfactants for high temperature steam foam applications has been investigated using both a new bulk foam screening test and core testing in the presence and absence of bitumen. A new screening methodology utilizing a high pressure cell fitted with viewing windows is described. Data is presented for the initiation and degradation rate of bulk foams for a number of surfactants at 190°C and 250°C.
Two surfactants Agent X and Agent Z were examined in core flood in the presence and absence of bitumen. At both 190°C and 250°C, the foaming agents were capable of creating stable foam. Core flood results in ~15 D sand pack at 250°C show that in the absence of bitumen, Agent X and Agent Z were capable of creating apparent foam viscosities of 3.9 and 17.7 cP, respectively. In the presence of bitumen the foaming ability was decreased, but foams created by both surfactants still maintained apparent viscosities of >1 cP. Both surfactants produced foams that have shown shear thinning behavior under the conditions tested. Potential applications for high temperature foams are discussed in light of the results.
We report on a novel low-cost approach for producing large format flexible RGB phosphor sheets with applications in both lighting and displays. The process can utilize any conventional down-conversion/up-conversion phosphor or non-phosphor optical powder materials regardless of particle size, shape, and composition. Both monochrome and patterned phosphor sheets can be produced in widths larger than 50 inch and lengths over 50 meters by roll-to-roll. Substrate thickness can vary from 50 microns (2 mils) to over 500 microns (20 mils) with monolayer control over phosphor coating thickness and better than 5% color uniformity. This technology is currently being used to produce high performance remote phosphor sheets for phosphorconverted white LEDs with ultra-high color rendering index (CRI>96) and correlated color temperature (CCT) from 2700K to over 8000K. A customized red/green phosphor film has also been shown to deliver 100% of NTSC color gamut for LCD display applications when combined with a blue LED.
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