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We report the performance of a quinone-bromide redox flow battery and its dependence on electrolyte composition, flow rate, operating temperature, electrode and membrane materials and pre-treatment. The results of this study are used to develop a cell with a peak galvanic power density reaching 1.0 W/cm 2 .Redox flow batteries (RFBs) are promising candidates for the integration of intermittent renewable power sources with the power grid due to their potential for high safety and long discharge duration at low cost. 1-5 The most technologically mature system -the vanadium RFB -has now reached a peak power density of 1.34 W/cm 2,6 but the high price of vanadium sets a high floor on the system cost per kWh. Redox-active organics in aqueous solution have received recent attention due to their high performance and low cost, 7-9 with initial reports of peak galvanic power densities reaching 0.6 W/cm 2 in nonoptimized cells. 7 Here we study the performance of a quinone-bromide flow battery (QBFB) and its dependence on electrolyte composition, flow rate, operating temperature, electrode and membrane materials and pre-treatment of these materials. The results of this study are used to raise the peak galvanic power density to 1.0 W/cm 2 . ExperimentalThe cell design ( Fig. 1) is based on that in Ref. 7. On each side, a commercial graphite plate with interdigitated flow channels 10 (Fuel Cell Tech, Albuquerque, NM) was used to feed electrolyte to a porous carbon paper electrode at a rate controlled by a MasterFlex (Cole Parmer) diaphragm pump. The temperature of the cell was controlled by heating tapes from 20 to 45 • C, a range anticipated to be encountered in normal operation. The electrode comprised a stack of 6 sheets of Toray 060 (each nominally 200 μm thick), or 3 sheets of SGL 10AA (each nominally 400 μm thick) carbon paper, compressed to ∼75% of the original thickness, defined by Teflon gaskets. The geometric area of the electrodes was 2 cm 2 . No electrocatalyst was added to the carbon papers. The Toray paper was pre-treated, first by sonication in isopropanol, and then by etching in a 1:3 (v/v) mixture of concentrated nitric and sulfuric acids at 50 • C for 5 hours. The SGL paper was pretreated by baking at 400 • C in air for 24 hours. The two papers were pre-treated differently because we noticed that the same etching protocol caused significant damage to the SGL paper which subsequently fractured upon handling. A Nafion membrane of variable thickness served as the ion-selective membrane. Its pre-treatment consisted of heating in DI water at 85 • C for 15 min., followed by soaking in 5% hydrogen peroxide for 30 min., and then by soaking in 0.05 M H 2 SO 4 for 1 hour. Assembled fully discharged, the negative electrolyte ("negolyte") (20 mL) contained 1 M 9,10-anthraquinone-2,7-disulfonic acid (AQDS), ion exchanged from its sodium salt (TCI) and 1 M H 2 SO 4 , and the positive electrolyte ("posolyte") (24 mL) contained 3 or 3.5 M hydrobromic acid and 0.5 or 2 M Br 2 . The nominal reactions during the charging proce...

RNA interference (RNAi) for anti-angiogenic or pro-apoptotic factors in endothelial cells (ECs) has great potential for the treatment of ischemic diseases by promoting angiogenesis or inhibiting apoptosis. Here, we report the utility of small interfering RNA (siRNA) in inhibiting EC apoptosis induced by tumor necrosis factor-α (TNF-α). siRNA was designed and synthesized targeting tumor necrosis factor-α receptor-1 (TNFR-1) and Src homology 2 domain-containing protein tyrosine phosphatase-1 (SHP-1). Human umbilical vein endothelial cells (HUVECs) were cultured under in vitro hypoxic and serum-deprived conditions to simulate in vivo ischemic conditions. Two days after liposomal delivery of siRNA targeting TNFR-1 and SHP-1, significant silencing of each target (TNFR-1; 76.5 % and SHP-1; 97.2 %) was detected. Under serum-deprived hypoxic (1% oxygen) conditions, TNF-α expression in HUVECs increased relative to normoxic (20% oxygen) and serum-containing conditions. Despite enhanced TNF-α expression, suppression of TNFR-1 or SHP-1 by siRNA delivery not only enhanced expression of angiogenic factors (KDR/Flk-1 and eNOS) and anti-apoptotic factor (Bcl-xL) but also reduced expression of a pro-apoptotic factor (Bax). Transfection of TNFR-1 or SHP-1 siRNA significantly decreased the HUVEC apoptosis while significantly enhancing HUVEC proliferation and capillary formation. The present study demonstrates that TNFR-1 and SHP-1 may be useful targets for the treatment of myocardial or hindlimb ischemia.

Zinc oxysulfide, Zn(O,S), films grown by atomic layer deposition (ALD) were incorporated with aluminum to adjust the carrier concentration. The electron carrier concentration increased up to one order of magnitude from 10 19 to 10 20 cm -3 with aluminum incorporation and sulfur content in the range of 0 ≤ S/(Zn+Al) ≤ 0.16. However, the carrier concentration decreased by five orders of magnitude from 10 19 to 10 14 cm -3 for S/(Zn+Al) = 0.34, and decreased even further when S/(Zn+Al) > 0.34. Such tunable electrical properties are potentially useful for graded buffer layers in thin-film photovoltaic applications. Cu 2 ZnSn(Se,S) 4 (CZTS), [3][4][5] Compared to the conventional toxic CdS buffer material for CIGS and CZTS solar cells, Zn(O,S) is composed of earth-abundant and non-toxic elements. KeywordsThis ternary n-type buffer material also has the advantage of having the ability to adjust the band alignment through fine tuning of the stoichiometry, which is easily achieved by atomic layer deposition (ALD) through varying the precursor pulse ratios. [10][11][12] Increasing the sulfur content in Zn(O,S) raises the conduction band energy, which is critical in adjusting the conduction band offset (CBO) at the buffer/absorber interface to optimize the solar cell device performance, 13 as illustrated for SnS/Zn(O,S) heterojunctions in Fig. S1 (see Ref. 14). If the conduction band energy of the buffer layer is too low compared to that of the absorber layer, the negative CBO will induce recombination at the buffer/absorber interface via defects (Fig. S1a). 15 If the conduction band energy of the buffer layer is too high compared to that of the absorber layer, the positive CBO at the buffer/absorber interface creates a barrier that prevents electrons from flowing across the junction towards the transparent conducting oxide (TCO) layer ( Although it has been demonstrated that low electron carrier concentration of Zn(O,S) can improve SnS-based solar cells, this can increase contact resistance with the TCO layer by adding series resistance to the solar cell, which reduces the short-circuit current density (J SC ). While a low carrier concentration of Zn(O,S) can be beneficial for the portion of the buffer layer closer to the absorber layer to reduce possible recombination occurring at the absorber/buffer interface, a high carrier concentration of Zn(O,S) can be beneficial for the portion of the buffer layer closer to the TCO layer to reduce contact resistance. Aluminum is a well known dopant for increasing the electron carrier concentration of ZnO for TCO applications. 18,19 In this study, we report that the electron carrier concentration of ALD Zn(O,S) can be either increased or decreased by modifying the stoichiometry of the film with aluminum incorporation, which is potentially useful for graded buffer layers in thin-film solar cell applications.A custom-built hot-wall ALD reactor was used to grow Zn(O,S) and Al-incorporated Zn(O,S) films. Films were grown at a deposition temperature of 120°C in closed valve mode...

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