• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.417-417
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• 2016

Global environmental deterioration has become more serious year by year and thus scientific interests in the renewable energy as environmental technology and replacement of fossil fuels have grown exponentially. Photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly to split water, also known as photoelectrolysis or solar water splitting, is a promising renewable energy technology to produce hydrogen for uses in the future hydrogen economy. A major advantage of PEC systems is that they involve relatively simple processes steps as compared to many other H2 production systems. Until now, a number of materials including TiO2, WO3, Fe2O3, and BiVO4 were exploited as the photoelectrode. However, the PEC performance of these single absorber materials is limited due to their large charge recombinations in bulk, interface and surface, leading low charge separation/transport efficiencies. Recently, coupling of two materials, e.g., BiVO4/WO3, Fe2O3/WO3 and CuWO4/WO3, to form a type II heterojunction has been demonstrated to be a viable means to improve the PEC performance by enhancing the charge separation and transport efficiencies. In this study, we have prepared a triple-layer heterojunction BiVO4/WO3/SnO2 photoelectrode that shows a comparable PEC performance with previously reported best-performing nanostructured BiVO4/WO3 heterojunction photoelectrode via a facile solution method. Interestingly, we found that the incorporation of SnO2 nanoparticles layer in between WO3 and FTO largely promotes electron transport and thus minimizes interfacial recombination. The impact of the SnO2 interfacial layer was investigated in detail by TEM, hall measurement and electrochemical impedance spectroscopy (EIS) techniques. In addition, our planar-structured triple-layer photoelectrode shows a relatively high transmittance due to its low thickness (~300 nm), which benefits to couple with a solar cell to form a tandem PEC device. The overall PEC performance, especially the photocurrent onset potential (Vonset), were further improved by a reactive-ion etching (RIE) surface etching and electrocatalyst (CoOx) deposition.

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.167-172
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• 2010

Purpose : With improved survival of extremely low birth weight infants (ELBWI), there is an increase in the incidence of necrotizing enterocolitis (NEC) requiring laparotomy, and the risk of morbidity and mortality in these ELBWI is increased. Thus, we determined the prognostic factors in ELBWI who underwent laparotomy for NEC. Methods : We retrospectively reviewed the medical records of 35 ELBWI who underwent laparotomy for NEC from January 2001 to December 2008 at Samsung Medical Center. Results : Of 480 ELBWI, 35 required laparotomy for NEC; the mortality rate was 20% (Alive group n=28, Dead group n=7). The values of preoperative score for neonatal acute physiology-II (P =0.022) and fraction of inspired oxygen (P <0.001) were significantly higher in the dead group and values of base excess (P =0.004) were significantly lower in the dead group. Values of preoperative heart rate, respiration rate, mean blood pressure, pH, $CO_2$, and potassium ion were not significantly different between the study groups. Intraoperative fluid volume was significantly higher in the alive group than in the dead group (P =0.045). Postoperative infusion rate was significantly lower in the alive group than in the dead group (P =0.022). Conclusion : Good preoperative condition, more intraoperative fluid infusion, and stable postoperative hemodynamic condition were factors associated with favorable prognosis of laparotomy for NEC in ELBWI.