Mitral Loop Cerclage Annuloplasty for Secondary Mitral Regurgitation

Park, Y.H.,Chon, M.K.,Lederman, R.J.,Sung, S.C.,Je, H.G.,Choo, K.S.,Lee, S.H.,Shin, E.S.,Kim, J.S.,Hwang, K.W.,Lee, S.Y.,Chun, K.J.,Kim, C.M.,Kim, J.H. Elsevier 2017 JACC. Cardiovascular interventions Vol.10 No.6

<P>OBJECTIVES This is an early feasibility clinical test of mitral loop cerclage annuloplasty to treat secondary mitral valve regurgitation. BACKGROUND Secondary mitral regurgitation is characterized by cardiomyopathy, mitral annular enlargement, and leaflet traction contributing to malcoaptation. Transcatheter mitral loop cerclage applies circumferential compression to the mitral annulus by creating a loop through the coronary sinus across the interventricular septum, protecting entrapped coronary arteries from compression, and interactive annular reduction under echocardiographic guidance. This is the first human test of mitral loop annuloplasty. METHODS Five subjects with severe symptomatic secondary mitral regurgitation underwent mitral loop cerclage, with echocardiographic and computed tomography follow-up over 6 months. RESULTS Mitral loop cerclage was successful in 4 of 5 subjects and aborted in 1 of the 5 because of unsuitable septal coronary vein anatomy. Immediately and over 6 months, measures of both mitral valve regurgitation (effective orifice area and regurgitation fraction) and chamber dimensions (left atrial and left ventricular volumes) were reduced progressively and ejection fractions increased. Two with persistent and permanent atrial fibrillation spontaneously reverted to sinus rhythm during follow-up. One subject experienced a small myocardial infarction from an unrecognized small branch coronary occlusion. Another, experiencing cardiogenic shock at baseline, died of intractable heart failure after 6 weeks. CONCLUSIONS In this first human test, mitral loop cerclage annuloplasty was successful in 4 of 5 attempts, caused reverse remodeling (reduction in secondary mitral regurgitation and heart chamber volumes), and suggested electrical remodeling (reversion of atrial fibrillation). Further evaluation is warranted. (C) 2017 by the American College of Cardiology Foundation. Published by Elsevier. All rights reserved.</P>

Orbital hybridization mechanism for the enhanced photoluminescence in edge-functionalized sp² carbon clusters

Kang, B.,Choi, Y.,Kim, B.S.,Youn, I.S.,Lee, G. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.109 No.-

<P>Using the first principles methods, we performed systematic study on the effect of edge-functional groups on the electronic energy levels and the optical properties of sp(2) carbon clusters. It is found that the intrinsic pi and pi* orbitals are weakly altered by oxygen-bearing functional groups, but it is significantly disrupted by pyrrolic groups. Thereby the oscillator strength of the lowest-energy transition is found to be much stronger for the pyrrolic group functionalized cluster than for the carboxyl group. From our results being consistent with the experimental reports, we suggest that the photoluminescence enhancement is caused by a perturbation of the intrinsic, frontier molecular orbitals by edge groups. (C) 2016 Elsevier. Ltd. All rights reserved.</P>

Fabrication and device characterization of potassium fluoride solution treated CZTSSe solar cell

Rana, T.R.,Kim, J.,Sim, J.H.,Yang, K.J.,Kim, D.H.,Kang, J.K. Elsevier 2017 Current Applied Physics Vol.17 No.10

<P>Post deposition treatment (PDT) for Cu2ZnSn(S,Se)(4) (CZTSSe) was carried out by simply dipping the absorber into the KF solution at 80 degrees C. The dipping time of absorber in KF solution was found to be crucial to device parameters of CZTSSe solar cell. The K-doping improved the solar cell efficiency from 4.4% to 7.6% by 1 min dipping whereas the longer than 5 min dipping solar cells showed distorted kink J-V curves. The activation energy of CZTSSe solar cell was increased upto 1 min KF treatment from 0.83 eV to 0.92 eV which indicates interface recombination is reduced significantly. However, the activation energies of 5 min and 10 min dipping solar cells were found to be 0.81 eV and 0.63 eV where dominant recombination was interface recombination. Furthermore, trap energies of 49 meV and 298 meV of pristine CZTSSe solar cell were modified to 33 meV and 117 meV for 1 min treated CZTSSe solar cell. Trap energies of 5 min were calculated to be 112 meV and 147 meV. The proper KF doping passivated the shallow as well as deep defects of CZTSSe solar cell which is reflected in photovoltaic performances directly. (C) 2017 Elsevier B.V. All rights reserved.</P>

Facile hydrothermal synthesis of Eu³⁺-activated NaYF₄ nanocrystals and their Judd-Ofelt analysis, photoluminescence and cathodoluminescence properties

Du, P.,Yu, J.S. Elsevier 2017 Current Applied Physics Vol.17 No.12

<P>The Eu3+-activated NaYF4 nanocrystals were synthesized via a facile hydrothermal technique. The resultant compounds were characterized by X-ray diffraction pattern, transmission electron microscope images and photoluminescence (PL)/cathodoluminescence (CL) spectra. Under near-ultraviolet light excitation, the characteristic emissions of Eu3+ ions were detected in the prepared nanocrystals and the red emission at 615 nm originating from the D-5(0) -> F-7(2) transition dominated in the emission spectrum. The luminescent spectrum revealed that the Eu3+ ions populated the low symmetry sites in NaYF4 lattices. Furthermore, a theoretical calculation based on the Judd-Ofelt theory was performed to evaluate the intensity parameters to further explore the local structure environment surrounding Eu3+ ions in NaYF4 lattices. The temperature-dependent PL emission spectra were recorded to study the thermal stability of the resultant nanocrystals and the activation energy was determined to be 0.149 eV. Ultimately, the CL properties of the final products as a function of accelerating voltage and filament current were investigated. These results revealed that the synthesized nanocrystals are a promising candidate for white light-emitting diodes and field emission displays as red-emitting phosphors. (C) 2017 Elsevier B.V. All rights reserved.</P>

Fe-based multifunctional nanoparticles with various physicochemical properties

Kwon, J.,Mao, X.,Lee, J. Elsevier 2017 Current Applied Physics Vol.17 No.8

<P>Over the past few decades, many studies have assessed Fe-based nanoparticles because of their high earth abundance, inexpensive precursors, unique optical properties, electromagnetic nature, biocompatibility, and interactivity with cells. By controlling the composition of a composite, the morphology, size, physical properties, and related functionalities, the synthesized nanomaterials can be altered for specific applications. This review introduces several methods for synthesizing iron-based binary/ternary chalcogenides, iron-based bimetallic materials, and iron-based magnetoplasmonic materials with a range of properties. Furthermore, assembled nanostructures make it possible for us to use these building blocks for broader and customized applications depending on their controlled arrangement. This will facilitate the potential application of iron-based functional materials in spintronics, biomedicine, electronics, and catalysis. (C) 2017 Published by Elsevier B.V.</P>

Effect of device structure on the resistive switching characteristics of organic polymers fabricated through all printed technology

Rehman, M.M.,Yang, B.S.,Yang, Y.J.,Karimov, K.S.,Choi, K.H. Elsevier 2017 Current Applied Physics Vol.17 No.4

<P>Developments in organic bi-stable non-volatile memory devices have shown that organic materials are essential for the next generation of electrical memory unit owing to their low cost, high flexibility and large scalability. This study depicts an important aspect of organic memory devices by observing the effect of changing device structure on its switching characteristics. Memory devices with a bilayer and bulk-heterojunction structure were fabricated through an all printed technology by utilizing two organic polymers such as MEH: PPV and PMMA. Silver (Ag) was selected as the top and bottom electrode due to its high conductivity and easy processing. Though identical polymers were used in both device structures, but interestingly change in structure caused change in properties. It was observed that bilayer structure had much higher switching ratio and stability against various biasing cycles as compared to its bulk-heterojunction counterpart. Superior switching characteristics of bilayer structure were due to the presence of a well-defined interface between both polymers. Bulk-heterojunction device suffers the drawback of phase separation in a single organic layer between the two polymers. (C) 2017 Elsevier B.V. All rights reserved.</P>

Highly stretchable polymer composite microtube chemical sensors produced by the meniscus-guided approach

Won, K.H.,Weon, B.M.,Je, J.H. Elsevier 2017 Current Applied Physics Vol.17 No.3

<P>Highly stretchable polymer composite microtubes of poly(methyl methacrylate)/polypyrrole (PMMA/ PPy) were produced as a microarch shape by a meniscus -guided approach using colloidal solutions of the composite polymers. The polymer composite (PMMA/PPy) microarches show high stretchability up to 80% maintaining the electrical properties. Moreover, the microarches endure repeated stretching over 104 (9 x 102) cycles at 20% (80%) stretching without degradation of the electrical properties. The stretchable PMMA/PPy microtube arches are demonstrated as gas sensors with persistent sensitivities and response (recovery) times up to 80% stretching for various NH3 concentrations. These robust properties of the stretchable PMMA/PPy microtube arch sensors can be suitable for portable sensing devices operating under extreme stretching conductions to be used in research laboratories and chemical processing industries for chemical leak detection and environmental monitoring. (C) 2016 Elsevier B.V. All rights reserved.</P>

Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

Mohan Kumar, G.,Ilanchezhiyan, P.,Madhan Kumar, A.,Yuldashev, Sh.U.,Kang, T.W. Elsevier 2016 Chemical physics letters Vol.649 No.-

<P>A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current-voltage characteristics on the fabricated PPy/A1 doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications. (C) 2016 Elsevier B.V. All rights reserved.</P>

Magnetoelectricity in Fe/PbTiO₃/Fe superlattices

Elsevier 2017 Current Applied Physics Vol.17 No.5

<P>Using the first-principles density functional calculations, we have investigated the magnetoelectric coupling at the Fe/PbTiO3/Fe superlattices by varying the number of ferroelectric PbTiO3 layers. We find that the change of Fe magnetization is electrically tunable, almost linear in the depolarizing field, and occurs very near the superlattice interface region. The maximal magnetoelectric coupling constant in the. Fe/PbTiO3/Fe superlattices is estimated to be about 4 x 10(-10) G cm(2)/V, which is quite similar order of magnitude as that recently experimentally achieved in Co (7 nm)/Pb(Zr,Ti)O-3. (C) 2017 Elsevier B.V. All rights reserved.</P>

Simple active-layer patterning of solution-processed a-IGZO thin-film transistors using selective wetting method

Lee, S.,Jeong, J. Elsevier 2017 Current Applied Physics Vol.17 No.12

<P>In this paper, we report a selective-patterning method of active layers for the fabrication of solution-based amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs). Using simple stamping of a reusable poly(dimethylsiloxane) (PDMS) substrate onto a SiOX/Si substrate, the surface of SiOx/Si was easily changed to the hydrophobic state because the PDMS substrate contains a large amount of methyl ligands. By combining oxygen plasma treatments through a shadow mask, the active layer was self-defined through selective coating of the a-IGZO solution owing to the difference of the wetting properties. The electrical performance of the resulting TFTs was comparable with that of TFTs fabricated with the conventional method. Because the proposed method is very simple and the PDMS substrate is reusable compared to other selective-wetting methods that use self-aligned monolayers, it is expected to be applicable to the fabrication of low-cost and large-area electronic applications. (C) 2017 Elsevier B.V. All rights reserved.</P>