Bipolar electrochemistry for enrichment, separations, and membraneless electrochemically mediated desalination

Developments in bipolar electrochemistry for the simultaneous separation and enrichment of charged species and membraneless electrochemically mediated desalination (EMD) are presented. Each of these techniques requires an electrochemically generated local electric field within a microchannel and control over bulk fluid flow. In addition to bipolar electrochemical studies, investigations of ion depletion zone formation and EMD in a two-electrode microelectrochemical cell are presented. The dual-channel bipolar electrode (BPE) configuration is employed for the simultaneous enrichment and separation of anions and cations within a single microchannel at an ion depletion zone generated by buffer neutralization. Moreover, this experimental design is also used to generate an ion depletion zone and associated electric field gradient by Cl⁻ oxidation, where we demonstrate partial seawater desalination without the need for a physical membrane. Expanding upon the fundamentals of BPE focusing, we demonstrate proof-of-concept biomolecule separation and enrichment. Moreover, without the need for a direct external electrical connection, one hundred BPEs are operated simultaneously in parallel to enrich multiple analyte bands. Metal deposition at a BPE is used to mediate BPE focusing. Ion depletion zones arising from Cl⁻ oxidation are investigated by making axial electric field measurements while varying key experimental parameters affecting ion depletion zone formation, location, and strength. We investigate the capabilities of EMD by modifying the electrode design to increase the local electric field strength in an effort to increase the percentage of salt rejection. We also examine the possibility to lower, or even eliminate the electrical energy requirements of EMD by driving Cl⁻ oxidation photoelectrochemically. Lastly, on-line capacitively coupled contactless conductivity measurements are presented to rapidly and reliably quantify ion separation for EMD.Chemistr

The Effects of Using iPads to Increase Basic Math Fact Automaticity

Our investigation was on the effects of using iPads to increase basic fact automaticity. We wanted to explore what strategy worked best to increase fact fluency: flashcards and paper/pencil practice or iPad practice. The project took place in one fourth-grade classroom and one fifth-grade classroom. The fourth-grade classroom had twenty-one students. The fifth-grade classroom had twenty-two students. We collected data with pretest and posttest instruments. We also collected data through weekly observations. Students using the iPads were also monitored using the Moby Max fact fluency program. The results indicated that daily flashcard and paper/pencil practice provided a higher rate of improvement of fact fluency on a two-minute test. We concluded that although the data does not indicate a higher rate of improvement by using iPads, other factors must also be included. One important factor was that the students who showed the greatest improvement also happened to be in the fifth-grade classroom. The implication for us is that we will use a combination of iPad practice along with the flashcard and paper/pencil review to increase student mathematics fluency