16 research outputs found

    Composite fiber structures for catalysts and electrodes

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    We have recently envisioned a process wherein fibers of various metals in the 0.5 to 15 micron diameter range are slurried in concert with cellulose fibers and various other materials in the form of particulates and/or fibers. The resulting slurry is cast via a wet-lay process into a sheet and dried to produce a free-standing sheet of 'composite paper.' When the 'preform' sheet is sintered in hydrogen, the bulk of the cellulose is removed with the secondary fibers and/or particulates being entrapped by the sinter-locked network provided by the metal fibers. The resulting material is unique, in that it allows the intimate contacting and combination of heretofore mutually exclusive materials and properties. Moreover, due to the ease of paper manufacture and processing, the resulting materials are relatively inexpensive and can be fabricated into a wide range of three-dimensional structures. Also, because cellulose is both a binder and a pore-former, structures combining high levels of active surface area and high void volume (i.e., low pressure drop) can be prepared as freestanding flow through monoliths

    Expansion of cytotoxic natural killer cells in multiple myeloma patients using K562 cells expressing OX40 ligand and membrane-bound IL-18 and IL-21.

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    BACKGROUND: Natural killer (NK) cell-based immunotherapy is a promising treatment approach for multiple myeloma (MM), but obtaining a sufficient number of activated NK cells remains challenging. Here, we report an improved method to generate ex vivo expanded NK (eNK) cells from MM patients based on genetic engineering of K562 cells to express OX40 ligand and membrane-bound (mb) IL-18 and IL-21. METHODS: K562-OX40L-mbIL-18/-21 cells were generated by transducing K562-OX40L cells with a lentiviral vector encoding mbIL-18 and mbIL-21, and these were used as feeder cells to expand NK cells from peripheral blood mononuclear cells of healthy donors (HDs) and MM patients in the presence of IL-2/IL-15. Purity, expansion rate, receptor expression, and functions of eNK cells were determined over four weeks of culture. RESULTS: NK cell expansion was enhanced by short exposure of soluble IL-18 and IL-21 with K562-OX40L cells. Co-culture of NK cells with K562-OX40L-mbIL-18/-21 cells resulted in remarkable expansion of NK cells from HDs (9,860-fold) and MM patients (4,929-fold) over the 28-day culture period. Moreover, eNK cells showed increased expression of major activation markers and enhanced cytotoxicity towards target K562, U266, and RPMI8226 cells. CONCLUSIONS: Our data suggest that genetically engineered K562 cells expressing OX40L, mbIL-18, and mbIL-21 improve the expansion of NK cells, increase activation signals, and enhance their cytolytic activity towards MM cells

    Performances and thermal stability of LiCoO2 cathodes encapsulated by a new gel polymer electrolyte

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    A unique approach for improving the thermal stability of delithiated LiCoO2 cathodes has been presented, which is based on the encapsulation of LiCoO2 by a new cyano-substituted polyvinylalcohol (cPVA)-based gel polymer electrolyte. In a bid to maximize the effect of encapsulation, the cPVA-based gel polymer electrolyte was applied to the LiCoO2 cathode with a predetermined degree of porosity. Through this new process, the gel polymer electrolyte is expected to locate preferentially onto the LiCoO2 at well-controlled thickness, with the overall porous structure of the modified cathode being little influenced. Due to the presence of cyano ({single bond}CN) groups, the cPVA shows high dielectric constant (?? = 15 at 1 kHz at 20 ??C), which is thus expected to enhance the Li-salt dissociation, leading to the excellent ionic conductivity (around 7 mS cm at 25 ??C). Under the assumption that the LiCoO2 could be fully covered with the cPVA, the encapsulated thickness is calculated around 10 nm, which was further evidenced by the FE-SEM results. Meanwhile, compared to the pristine LiCoO2 cathode (??H = 413 J g-1), the modified LiCoO2 cathode exhibited the superior thermal stability (??H = 31 Jg-1) and also presented the satisfactory C-rate performances and cyclability. Such a remarkable enhancement in the thermal stability and the electrochemical performances has been discussed on the basis of the morphology of the modified LiCoO2 cathode and the electrochemical properties of the cPVA-based gel polymer electrolytes.close3

    Nano-encapsulation of LiCoO2 cathodes by a novel polymer electrolyte and its influence on thermal safeties of Li-ion batteries

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    A new approach enabling the target control of exothermic reaction between delithiated LiCoO2 and liquid electrolytes has been presented, which is based on the nano-encapsulation of LiCoO2 by cPVA (cyanoethyl polyvinylalcohol)-based gel polymer electrolytes. This novel morphology and the possible formation of coordinated complexes between the cyano (-CN) groups of cPVA and the cobalt cations of LiCoO2 are considered as key factors to significantly suppress the exothermic reaction in the delithiated LiCoO2. Such an improved thermal stability of the cPVA-modified LiCoO2 has led to a noticeable achievement in the hot-oven safety behavior of cells. Meanwhile, it was observed that both the excellent ionic conductivity of cPVA-based gel polymer electrolytes and the well-preserved porous structure of modified cathodes contribute to the satisfactory C-rate capability and the cyclability of cells.close10

    A study of nucleate boiling heat transfer on hydrophilic, hydrophobic and heterogeneous wetting surfaces

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    The effect of characteristic of heating surface on nucleate boiling heat transfer is well reported via many previous results. However, until recently, the study of surface influences on nucleate boiling was complicated by coupled surface factors; wettability and surface roughness. This study focuses on nucleate pool boiling under different wetting conditions, in the absence of microscale roughness, which is coupled with wetting phenomena. Heterogeneous boiling occurs on hydrophilic (54ยฐ) and hydrophobic (123ยฐ) surfaces, even without microstructures that can trap water vapor. In the very low heat flux regime, hydrophobic surfaces offer better nucleate boiling heat transfer than hydrophilic surfaces. Moreover, a heterogeneous wettability surface composed of hydrophobic dots on a hydrophilic surface provides better nucleate boiling heat transfer than a homogeneous wettability surface (hydrophilic or hydrophobic). Analysis of bubble generation and departure was carried out via a high-speed visualization technique in order to understand these experimental results. Based on the bubble analysis, it was inferred that changes in wettability could lead to totally different boiling performance when microstructures are absent. Also, the number of hydrophobic dots and the pitch distance between dots were key parameters for explaining boiling performance under heterogeneous wetting conditions. ยฉ 2011 Elsevier Ltd. All rights reserved.X11133116Nscopu

    Nano-encapsulation of graphite-based anodes by a novel polymer electrolyte and its influence on C-rate performances of Li-ion batteries

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    A unique approach for improving the C-rate (charge/discharge) performances of lithium-ion batteries has been presented, which is based on the nano-encapsulation of graphite (MCMB, mesophase microbead) anodes by the cPVA (cyanoethyl polyvinylalcohol)-gel polymer electrolyte. Through this new process, the gel polymer electrolyte can effectively cover the MCMB surface at nanometer-scaled thickness. The novel morphology of the cPVA coating layer and its high polar -CN groups are considered as key factors to modify the MCMB surface to be electrolyte-philic. This increased polarity of MCMB is expected to allow the favorable impregnation of liquid electrolytes into the pores of the anode and finally contribute to the superior ionic conduction at the faster charge/discharge rates. In addition, it has been demonstrated that the nano-encapsulation of MCMB effectively suppressed the lithium-metal dendrite growth on the charged anode.close3
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