Microstructured porous ZnO thin film for increased light scattering and improved efficiency in inverted organic photovoltaics

Cataloged from PDF version of article.Microstructured porous zinc oxide (ZnO) thin film was developed and demonstrated as an electron selective layer for enhancing light scattering and efficiency in inverted organic photovoltaics. High degree of porosity was induced and controlled in the ZnO layer by incorporation of polyethylene glycol (PEG) organic template. Scanning electron microscopy, contact angle and absorption measurements prove that the ZnO: PEG ratio of 4:1 is optimal for the best performance of porous ZnO. Ensuring sufficient pore-filling, the use of porous ZnO leads to a marked improvement in device performance compared to non-porous ZnO, with 35% increase in current density and 30% increase in efficiency. Haze factor studies indicate that the performance improvement can be primarily attributed to the improved light scattering enabled by such a highly porous structure. (C) 2014 Optical Society of Americ

Efficacy and effectiveness of dihydroartemisinin-piperaquine versus artesunate-mefloquine in falciparum malaria: an open-label randomised comparison.

BACKGROUND: Artemisinin-based combinations are judged the best treatments for multidrug-resistant Plasmodium falciparum malaria. Artesunate-mefloquine is widely recommended in southeast Asia, but its high cost and tolerability profile remain obstacles to widespread deployment. To assess whether dihydroartemisinin-piperaquine is a suitable alternative to artesunate-mefloquine, we compared the safety, tolerability, efficacy, and effectiveness of the two regimens for the treatment of uncomplicated falciparum in western Myanmar (Burma). METHODS: We did an open randomised comparison of 3-day regimens of artesunate-mefloquine (12/25 mg/kg) versus dihydroartemisinin-piperaquine (6.3/50 mg/kg) for the treatment of children aged 1 year or older and in adults with uncomplicated falciparum malaria in Rakhine State, western Myanmar. Within each group, patients were randomly assigned supervised or non-supervised treatment. The primary endpoint was the PCR-confirmed parasitological failure rate by day 42. Failure rates at day 42 were estimated by Kaplan-Meier survival analysis. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN27914471. FINDINGS: Of 652 patients enrolled, 327 were assigned dihydroartemisinin-piperaquine (156 supervised and 171 not supervised), and 325 artesunate-mefloquine (162 and 163, respectively). 16 patients were lost to follow-up, and one patient died 22 days after receiving dihydroartemisinin-piperaquine. Recrudescent parasitaemias were confirmed in only two patients; the day 42 failure rate was 0.6% (95% CI 0.2-2.5) for dihydroartemisinin-piperaquine and 0 (0-1.2) for artesunate-mefloquine. Whole-blood piperaquine concentrations at day 7 were similar for patients with observed and non-observed dihydroartemisinin-piperaquine treatment. Gametocytaemia developed more frequently in patients who had received dihydroartemisinin-piperaquine than in those on artesunate-mefloquine: day 7, 18 (10%) of 188 versus five (2%) of 218; relative risk 4.2 (1.6-11.0) p=0.011. INTERPRETATION: Dihydroartemisinin-piperaquine is a highly efficacious and inexpensive treatment of multidrug-resistant falciparum malaria and is well tolerated by all age groups. The effectiveness of the unsupervised treatment, as in the usual context of use, equalled its supervised efficacy, indicating good adherence without supervision. Dihydroartemisinin-piperaquine is a good alternative to artesunate-mefloquine

Bariatric surgery and its impact on cardiovascular disease and mortality : A systematic review and meta-analysis

Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.Peer reviewedPostprin

Fast-Processing DEM-Based Urban and Rural Inundation Scenarios from Point-Source Flood Volumes

Flooding has always been a huge threat to human society. Global climate change coupled with unsustainable regional planning and urban development may cause more frequent inundations and, consequently, higher societal and economic losses. In order to characterize floods and reduce flood risk, flood simulation tools have been developed and widely applied. Hydrodynamic models for inundation simulation are generally sophisticated, yet they normally require massive setup and computational costs. In contrast, simplified conceptual models may be more easily applied and efficient. Based on the Hierarchical Filling-and-Spilling or Puddle-to-Puddle Dynamic Filling-and-Spilling Algorithms (i.e., HFSAs), Safer_RAIN has been developed as a fast-processing DEM-based model for modelling pluvial flooding over large areas. This study assesses Safer_RAIN applicability outside the context for which it was originally developed by looking at two different inundation problems with point-source flooding volumes: (1) rural inundation modelling associated with levee breaching/overtopping; (2) urban flooding caused by drainage systems outflow volumes

Effect of shell thickness on small-molecule solar cells enhanced by dual plasmonic gold-silica nanorods

Cataloged from PDF version of article.Chemically synthesized gold (Au)-silica nanorods with shell thickness of 0 nm-10 nm were incorporated into the bulk heterojunction of a small-molecule organic solar cell. At optimal (1 wt. %) concentration, Au-silica nanorods with 5 nm shell thickness resulted in the highest power conversion efficiency of 8.29% with 27% relative enhancement. Finite-difference time-domain simulation shows that the localized electric field intensity at the silica shell-organic layer interface decreases with the increase of shell thickness for both 520 nm and 680 nm resonance peaks. The enhanced haze factor for transmission/reflection of the organic layer is not strongly dependent on the shell thickness. Bare Au nanorods yielded the lowest efficiency of 5.4%. Light intensity dependence measurement of the short-circuit current density shows that the silica shell reduces bimolecular recombination at the Au surface. As a result, both localized field intensity and light scattering are involved in efficiency enhancement for an optimized shell thickness of 5 nm. (C) 2014 AIP Publishing LLC

Dye-sensitized solar cell with a pairof carbon-based electrodes

Cataloged from PDF version of article.We have fabricated a dye-sensitized solar cell (DSSC) with a pair of carbon-based electrodes using a transparent, conductive carbon nanotubes (CNTs) film modified with ultra-thin titanium-sub-oxide (TiOx) as the working electrode and a bilayer of conductive CNTs and carbon black as the counter electrode. Without TiOx modification, the DSSC is almost nonfunctional whereas the power conversion efficiency (PCE) increases significantly when the working electrode is modified with TiOx. The performance of the cell could be further improved when the carbon black film was added on the counter electrode. The improved efficiency can be attributed to the inhibition of the mass recombination at the working electrode/electrolyte interface by TiOx and the acceleration of the electron transfer kinetics at the counter electrode by carbon black. The DSSC with a pair of carbon-based electrodes gives the PCE of 1.37%

Free-standing ZnO-CuO composite nanowire array films and their gas sensing properties

Cataloged from PDF version of article.A modified hydrothermal method was developed to synthesize ZnO-CuO composite nanostructures. A free-standing film made of ZnO-CuO nanostructures was assembled on the surface of the hydrothermal solution with a smooth surface on one side and a spherical surface on the other side. The structure, growth mechanism and the optical properties of the composite nanostructures were studied. Structural characterizations indicate that the composite nanostructure mainly consisted of two single-crystal phases of CuO and ZnO. The sensitivity for CO gas detection was significantly improved for the composite CuO-ZnO nanostructure film. This method offers a possible route for the fabrication of free-standing nanostructure films of different functional composite oxides

Dye-sensitized solar cell with a titanium-oxide-modified carbon nanotube transparent electrode

Cataloged from PDF version of article.Transparent and conductive carbon-based materials are promising for window electrodes in solid-state optoelectronic devices. However, the catalytic activity to redox reaction limits their application as a working electrode in a liquid-type dye-sensitized solar cell (DSSC). In this letter, we propose and demonstrate a transparent carbon nanotubes (CNTs) film as the working electrode in a DSSC containing iodide/triiodide redox couples. This implementation is realized by inhibiting the charge-transfer kinetics at CNT/redox solution interface with an aid of thin titanium oxide film that facilitates the unidirectional flow of electrons in the cell without sacrificing the electrical and optical properties of CNT. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3610488

Top-illuminated dye-sensitized solar cells with a room-temperature-processed ZnO photoanode on metal substrates and a Pt-coated Ga-doped ZnO counter electrode

Cataloged from PDF version of article.We report on top-illuminated, fluorine tin oxide/indium tin oxide-free (FTO/ITO-free), dye-sensitized solar cells (DSCs) using room-temperature-processed ZnO layers on metal substrates as the working electrodes and Pt-coated Ga-doped ZnO layers (GZO) as the counter electrodes. These top-illuminated DSCs with GZO render comparable efficiency to those employing commercial FTO counter electrodes. Despite a lower current density, the top-illuminated DSCs result in a higher fill factor than conventional DSCs due to a low ohmic loss at the electrode/semiconductor interface. The effect of metal substrate on the performance of the resulting top-illuminated DSCs is also studied by employing various metals with different work functions. Ti is shown to be a suitable metal to be used as the working electrode in the top-illuminated device architecture owing to its low ohmic loss at the electrode/semiconductor interface, minimum catalytic activity on redox reactions and high resistance to corrosion by liquid electrolytes

Light Trapping in Inverted Organic Photovoltaics with Nanoimprinted ZnO Photonic Crystals

Zinc oxide photonic crystal (ZnO PC) formed via facile nanoimprinting was employed on the ZnO electron selective layer of inverted organic photovoltaics (OPV). Optimized inverted OPV fabricated with these highly ordered periodic structures provided effective light trapping, which resulted in increased incident light absorption in the active layer. Consequently, OPVs with the ZnO PC layers show a 23% current density improvement compared with OPVs with planar ZnO layer. Finite-difference time-domain simulation studies show that the electric field intensity is significantly higher in the active layer for devices with ZnO PC structures in comparison with reference devices with planar ZnO electron selective layer. Nanoimprinted ZnO PC is, thus, a viable method for light absorption and efficiency enhancement in OPVs. � 2011-2012 IEEE