A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method

Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2) pores with a diameter of 70∼80 nm using this method. This thin film had a Pd/TiO2 nanoporous/SiO2/Si MIS layered structure with Pd-TiO2 as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO2 surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO2 interface work function, resulting in a change in the I–V characteristics

Efficacy of two different self-expanding nitinol stents for atherosclerotic femoropopliteal arterial disease (SENS-FP trial): study protocol for a randomized controlled trial

BACKGROUND: There have been few randomized control trials comparing the incidence of stent fracture and primary patency among different self-expanding nitinol stents to date. The SMART™ CONTROL stent (Cordis Corp, Miami Lakes, Florida, United States) has a peak-to-valley bridge and inline interconnection, whereas the COMPLETE™-SE stent (Medtronic Vascular, Santa Rosa, California, United States) crowns have been configured to minimize crown-to-crown interaction, increasing the stent's flexibility without compromising radial strength. Further, the 2011 ESC (European society of cardiology) guidelines recommend that dual antiplatelet therapy with aspirin and a thienopyridine such as clopidogrel should be administered for at least one month after infrainguinal bare metal stent implantation. Cilostazol has been reported to reduce intimal hyperplasia and subsequent repeat revascularization. To date, there has been no randomized study comparing the safety and efficacy of two different antiplatelet regimens, clopidogrel and cilostazol, following successful femoropopliteal stenting. METHODS/DESIGN: The primary purpose of our study is to examine the incidence of stent fracture and primary patency between two different major representative self-expanding nitinol stents (SMART™ CONTROL versus COMPLETE™-SE) in stenotic or occlusive femoropopliteal arterial lesion. The secondary purpose is to examine whether there is any difference in efficacy and safety between aspirin plus clopidogrel versus aspirin plus cilostazol for one month following stent implantation in femoropopliteal lesions. This is a prospective, randomized, multicenter trial to assess the efficacy of the COMPLETE™-SE versus SMART™ CONTROL stent for provisional stenting after balloon angioplasty in femoropopliteal arterial lesions. The study design is a 2x2 randomization design and a total of 346 patients will be enrolled. The primary endpoint of this study is the rate of binary restenosis in the treated segment at 12 months after intervention as determined by catheter angiography or duplex ultrasound. DISCUSSION: This trial will provide powerful insight into whether the design of the COMPLETE™-SE stent is more fracture-resistant or effective in preventing restenosis compared with the SMART™ CONTROL stent. Also, it will determine the efficacy and safety of aspirin plus clopidogrel versus aspirin plus cilostazol in patients undergoing stent implantation in femoropopliteal lesions. TRIAL REGISTRATION: Registered on 2 April 2012 with the National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov identifier# NCT01570803)

Composition-dependent phase separation of P3HT:PCBM composites for high performance organic solar cells

Phase separation of the poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) active layer was investigated by varying its relative ratio in the bulk heterojunction (BHJ) organic solar cells (OSCs). The UV/visible absorption spectra of P3HT and PCBM were proportional to their compositions in the active layer. However, the crystallinity of P3HT, characterized by X-ray diffraction (XRD), improved with increasing composition up to 50 wt.%, but then degraded upon any further increase in its composition above 50 wt.%. This unique phenomenon corresponded to the microstructure of the layer, which was analyzed using transmission electron microscopy (TEM). The fraction of the highly ordered fiber structure of P3HT increased as the P3HT composition increased up to 50 wt.% and decreased as the composition increased further, which was in accordance with the XRD results. The microstructure of the P3HT: PCBM active layer, determined by the composition-dependent phase separation, supported the optimized performance of the OSCs with the active layer composition of 50% P3HT and 50% PCBM. (c) 2010 Elsevier B.V. All rights reserved

Use of fluorine-doped tin oxide instead of indium tin oxide in highly efficient air-fabricated inverted polymer solar cells

The stability and efficiency of organic solar cells (OSCs) were improved using thermally stable fluorine-doped tin oxide (FTO) as the bottom electrode and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and TiO(2) as the buffer layers. The TiO(2) layer between FTO and the P3HT:PCBM active layer improved the interface characteristics for a better charge transfer. The PEDOT:PSS layer retarded the oxygen diffusion to the active layer. A maximum power conversion efficiency of 4.3% was obtained for the inverted structure of FTO/TiO(2)/P3HT:PCBM/PEDOT:PSS/Ag with a stable performance, and the cell retained over 65% of its initial efficiency after 500 h. Additionally, the OSCs were fabricated using all-solution based vacuum-free processes with screen printing for the Ag electrode and the results were comparable to the device that used an evaporated Ag electrode

Effect of P3HT:PCBM concentration in solvent on performances of organic solar cells

Focused on phase separation and morphologies of poly(3-hexylthiophene):[6,6]-phenyl C-61 butyric acid methyl ester (P3HT:PCBM) active layers, we studied the effect of preparation conditions of the active layer on photovoltaic performance by changing concentration of P3HT:PCBM in the solvent. The performances of the cells varied depending on concentration of P3HT:PCBM (1:1 ratio by weight) in solvent even with the same thickness. The P3HT:PCBM active layer is prepared in cell structure of ITO/PEDOT/P3HT:PCBM/Al by changing spin-coating speed with different concentrations (1, 2 and 3 wt%) in chlorobenzene. Here, it was found that both the P3HT:PCBM concentrations and spin-coating conditions affected the crystalline structure formation, interchain interaction, morphology and phase separation during drying process of solvent and subsequent annealing. (C) 2009 Elsevier B.V. All rights reserved

Hybrid inverted bulk heterojunction solar cells with nanoimprinted TiO2 nanopores

Photovoltaic devices with highly ordered nanoporous titanium dioxide (titania; TiO2) were fabricated to improve the photovoltaic performances by increasing TiO2 interface area. The nanoimprinting lithography technique with polymethyl methacrylate (PMMA) mold was used to form titania nanopores. The solar cell with poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C-61 butyric acid methyl ester (PCBM) active layer on nanoporous titania showed higher power conversion efficiency (PCE) of 1.49% than on flat titania of 1.18%. The improved efficiency using nanoporous titania is interpreted with the enhanced-charge separation and collection by increasing the interface area between TiO2. and active layer. (C) 2009 Elsevier B.V. All rights reserved

Enhanced Mechanical Properties and Anti–Inflammation of Poly(L–Lactic Acid) by Stereocomplexes of PLLA/PDLA and Surface–Modified Magnesium Hydroxide Nanoparticles

Poly(L–lactic acid) (PLLA), as a biodegradable polymer, has attracted attention for use as a biomaterial. In order to apply PLLA as a cardiovascular stent, stronger mechanical properties and anti–inflammatory effects against acidic by–products are required. In this study, PLLA/PDLA stereocomplex microparticles (SC) were developed and surface–modified magnesium hydroxide (MH) nanoparticles with oligolactide were combined with these PLLA composites. The SC improved the mechanical properties of the PLLA composites through the formation of stereocomplex structures. The surface–modified MH nanoparticles showed enhanced mechanical properties due to the stereocomplex structures formed by PLLA chains and inhibited inflammatory responses by pH neutralization as a result of MH. Additionally, the MH nanoparticles containing PLLA composites had antibacterial effects and increased the viability of human vascular endothelial cells. This technology is expected to have great potential in the development of PLLA composite materials for the production of various medical devices, such as cardiovascular stents

Optimizing low impact development (LID) for stormwater runoff treatment in urban area, Korea: Experimental and modeling approach

Currently, continued urbanization and development result in an increase of impervious areas and surface runoff including pollutants. Also one of the greatest issues in pollutant emissions is the first flush effect (FFE), which implies a greater discharge rate of pollutant mass in the early part in the storm. Low impact development (LID) practices have been mentioned as a promising strategy to control urban stormwater runoff and pollution in the urban ecosystem. However, this requires many experimental and modeling efforts to test LID characteristics and propose an adequate guideline for optimizing LID management. In this study, we propose a novel methodology to optimize the sizes of different types of LID by conducting intensive stormwater monitoring and numerical modeling in a commercial site in Korea. The methodology proposed optimizes LID size in an attempt to moderate FFE on a receiving waterbody. Thereby, the main objective of the optimization is to minimize mass first flush (MFF), which is an indicator for quantifying FFE. The optimal sizes of 6 different LIDs ranged from 1.2 mm to 3.0 mm in terms of runoff depths, which significantly moderate the FFE. We hope that the new proposed methodology can be instructive for establishing LID strategies to mitigate FFE.close

Advanced α-CSH/β-TCP-based injectable paste with magnesium hydroxide and vitamin D-incorporated PLGA microspheres for bone repair

With the development of minimally invasive approaches, calcium-based injectable bone paste has attracted attention as a synthetic alternative due to its biodegradability and analogous composition with native bone. However, this approach is associated with the problem of the materials being absorbed before new bone formation has occurred, with a high resorption, and degradation rate. Here, a poly(lactic-co-glycolic acid) (PLGA)/magnesium hydroxide (MH)/vitamin D (Vit D) microsphere-incorporated α-calcium sulfate hemihydrate (α-CSH)/beta-tricalcium phosphate (β-TCP) injectable paste was designed for the regeneration of bone tissue. The combination of the bioceramic particles with α-CSH demonstrated an appropriate setting time for ease of use in clinical practice and enhanced mechanical properties. Additionally, the introduction of a bone paste with the MH and Vit D-incorporated PLGA microsphere induced osteogenic differentiation and alleviated the inflammatory response, which may occur after massive bone surgery. Based on these findings, this paper presents a versatile bone paste that promotes osteogenesis and modulates the osteoimmune microenvironment for effective bone regeneration