281 research outputs found
Performance Metrics for the Objective Assessment of Capacitive Deionization Systems
In the growing field of capacitive deionization (CDI), a number of
performance metrics have emerged to describe the desalination process.
Unfortunately, the separation conditions under which these metrics are measured
are often not specified, resulting in optimal performance at minimal removal.
Here we outline a system of performance metrics and reporting conditions that
resolves this issue. Our proposed system is based on volumetric energy
consumption (Wh/m) and throughput productivity (L/h/m) reported for a
specific average concentration reduction, water recovery, and feed salinity. To
facilitate and rationalize comparisons between devices, materials, and
operation modes, we propose a nominal standard testing condition of removing 5
mM from a 20 mM NaCl feed solution at 50% water recovery for CDI research.
Using this separation, we compare the desalination performance of a
flow-through electrode (fte-CDI) cell and a flow between membrane (fb-MCDI)
device, showing how significantly different systems can be compared in terms of
generally desirable desalination characteristics. In general, we find that
performance analysis must be considered carefully so to not allow for ambiguous
separation conditions or the maximization of one metric at the expense of
another. Additionally, for context we discuss a number of important underlying
performance indicators and cell characteristics that are not performance
measures in and of themselves but can be examined to better understand
differences in performance
Evaluating Interaction of Cord Blood Hematopoietic Stem/Progenitor Cells with Functionally Integrated Three-Dimensional Microenvironments
Despite advances in ex vivo expansion of cord blood-derived hematopoietic stem/progenitor cells (CB-HSPC), challenges still remain regarding the ability to obtain, from a single unit, sufficient numbers of cells to treat an adolescent or adult patient. We and others have shown that CB-HSPC can be expanded ex vivo in two-dimensional (2D) cultures, but the absolute percentage of the more primitive stem cells decreases with time. During development, the fetal liver is the main site of HSPC expansion. Therefore, here we investigated, in vitro, the outcome of interactions of primitive HSPC with surrogate fetal liver environments. We compared bioengineered liver constructs made from a natural three-dimensional-liver-extracellular-matrix (3D-ECM) seeded with hepatoblasts, fetal liver-derived (LvSt), or bone marrow-derived stromal cells, to their respective 2D culture counterparts. We showed that the inclusion of cellular components within the 3D-ECM scaffolds was necessary for maintenance of HSPC viability in culture, and that irrespective of the microenvironment used, the 3D-ECM structures led to the maintenance of a more primitive subpopulation of HSPC, as determined by flow cytometry and colony forming assays. In addition, we showed that the timing and extent of expansion depends upon the biological component used, with LvSt providing the optimal balance between preservation of primitive CB HSPC and cellular differentiation. Stem Cells Translational Medicine 2018;7:271–282
Exceptional Water Desalination Performance with Anion-Selective Electrodes
Capacitive deionization (CDI) typically uses one porous carbon electrode that is cation adsorbing and one that is anion adsorbing. In 2016, Smith and Dmello proposed an innovative CDI cell design based on two cation-selective electrodes and a single anion-selective membrane, and thereafter this design was experimentally validated by various authors. In this design, anions pass through the membrane once, and desalinated water is continuously produced. In the present work, this idea is extended, and it is experimentally shown that also a choice for anion-selective electrodes, in combination with a cation-selective membrane, leads to a functional cell design that continuously desalinates water. Anion-selective electrodes are obtained by chemical modification of the carbon electrode with (3-aminopropyl)triethoxysilane. After chemical modification, the activated carbon electrode shows a substantial reduction of the total pore volume and Brunauer–Emmett–Teller (BET) surface area, but nevertheless maintains excellent CDI performance, which is for the first time that a low-porosity carbon electrode is demonstrated as a promising material for CDI.</p
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