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>

Dip-coating synthesis of high-surface area nanostructured FeB for direct usage as anode in metal/metalloid-air battery

Abrenica, Graniel Harne A.,Ocon, Joey D.,Lee, Jaeyoung Elsevier 2016 Current Applied Physics Vol.16 No.9

<P>Multi-electron reaction anodes have been exciting battery materials due to their exceptionally high energy densities. Herein, nanostructured iron borides (nanoFeB) have been synthesized via dip-coating chemical reduction in conjunction with a heat treatment procedure and were directly used as anodes in a metal/metalloid-air battery. The crystal structure, particle size, BET surface area, and electrochemical properties of iron boride samples treated at four different temperature conditions (200 degrees C, 300 degrees C, 400 degrees C, and 500 degrees C) were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption isotherms, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The nanoFeB heat-treated at 300 degrees C (nanoFeB(300)) exhibits the highest surface area among reported values in literature and demonstrates excellent anode discharge performance in a metal/metalloid-air battery. (C) 2016 Elsevier B.V. All rights reserved.</P>

N-H and S-H insertions over Cu(I)-zeolites as heterogeneous catalysts

Saha, P.,Jeon, H.,Mishra, P.K.,Rhee, H.W.,Kwak, J.H. Elsevier 2016 Molecular Catalysis Vol.417 No.-

<P>N-H and S-H insertion reactions of a-diazoesters into amines and thiols were conducted using various Cu(I)-zeolites, such as zeolite Y, Y USY, ZSM-5, and beta. All the Cu(I)-zeolites successfully catalyzed N-H insertion reactions with high product yields (70-82%) in aqueous solution at room temperature. Interestingly, Cu(l)-USY (Si/Al = 30) showed better activity for both N-H and S-H insertion reactions than Cu(I)-Y (Si/Al= 2.6), even though they have the same structure and the same +1 oxidation state for Cu. X-ray diffraction, transmission electron microscopy, and X-ray photoemission spectroscopy analysis of the fresh and used catalysts revealed that no noticeable change in the zeolite structure, oxidation state of Cu, or sintering of Cu occurred during the reactions. Furthermore, after being recycled four times, the catalysts showed only minor activity decreases, exhibiting conversion rates 70-80% of those of the fresh catalysts, demonstrating their stability under the current reaction conditions. Temperature programmed reduction experiments showed that reduction of Cu+ to Cu degrees occurred at ca. 300 degrees C over Cu(l)-USY, while it occurred at ca. 800 degrees C over Cu(I)-Y. The significantly higher activity of Cu(I)-USY than Cu(l)-Y may be due to the more electrophilic Cu centers on Cu(l)-USY, which is highly favorable for ylide formation, and therefore facilitates N-H and S-H insertions. (C) 2016 Elsevier B.V. All rights reserved.</P>

Synthesis of silver nanoparticles using analogous reducibility of phytochemicals

Oh, S.,Jang, M.,Kim, J.,Lee, J.,Zhou, H.,Lee, J. Elsevier 2016 Current Applied Physics Vol.16 No.7

<P>We demonstrate the synthesis of Ag nanoparticles (NPs) with diameters in the range 10-20 nm using two phytochemicals, gallic acid and protocatechuic acid, which have similar chemical structures but subtle differences in their chemical potentials. This subtlety in their potential difference improves the control over the reduction of Ag precursors such that their composition and concentration are optimized for both the nucleation and growth steps of NP synthesis. Both steps were carefully monitored using UV -vis spectrophotometry and electron microscopy. The surface interaction energy of the phytochemicals on the NPs was characterized using computational simulation, and electrochemical analysis was performed to calculate the chemical reducibility of the phytochemicals to Ag+ ions by cyclic voltammetry. A plausible mechanism of size control was suggested. This novel and valuable method to control the size and the size distribution of Ag NPs enables new applications in materials science, biomedical science, and chemical sensor development. (C) 2016 Elsevier B.V. All rights reserved.</P>

Pore size-controlled carbon aerogels for EDLC electrodes in organic electrolytes

Yang, I.,Kim, S.G.,Kwon, S.H.,Lee, J.H.,Kim, M.S.,Jung, J.C. Elsevier 2016 Current Applied Physics Vol.16 No.6

<P>Pore size-controlled carbon aerogels (CA_X) are prepared from two starting materials: resorcinol and formaldehyde. Carbon aerogels with different pore sizes are successfully obtained by simply varying the polymerization time (X) in the polycondensation of resorcinol and formaldehyde. Pore sizes of the carbon aerogels monotonically increase with increasing polymerization time. The pore size of the carbon aerogel plays an important role in determining its electrochemical behavior (i.e., specific capacitance in EDLC) especially at high current density. A sufficiently large pore size in a carbon aerogel is required for easy transport of electrolyte ions, and these types of carbon aerogels provide excellent electrochemical performance as an EDLC electrode. CA_20, which was polymerized for the longest time, have the largest pore size and the largest pore volume. CA_20 exhibit the highest specific capacitance due to facile electrolyte ion transport. As a result, design of carbon aerogels with a sufficiently large pore size while maintaining a high specific surface area is very important for developing carbon aerogels for use in EDLC electrodes. In addition, we propose a schematic reaction pathway for the preparation of carbon aerogels in ambient conditions from resorcinol and formaldehyde using a base catalyst based on the characterization results. (C) 2016 Elsevier B.V. All rights reserved.</P>

Dramatically enhanced performances and ideally controlled nano-morphology via co-solvent processing in low bandgap polymer solar cells

Kim, Y.J.,Jang, W.,Ahn, S.,Park, C.E.,Wang, D.H. Elsevier Science 2016 ORGANIC ELECTRONICS Vol.34 No.-

<P>The device performance of photovoltaics with a polymer: fullerene bulk heterojunction (BHJ) structure, consisting of DT-PDPP2T-TT donor polymer and poly(3-hexylthiophene):[6,6] phenyl-C-61-butyric acid methyl ester (PC61BM) acceptor compound, was investigated as a function of co-solvent composition. An enhancement of the photocurrent density and fill factor is observed in diodes made by spin-coating with chloroform mixed with ortho-dichlorobenzene, which allows a significantly higher device efficiency of 5.55% compared to diodes made from neat chloroform (efficiency = 3.61%). To clarify the role of the co-solvent, we investigated the nanoscale morphology with AFM, TEM and 2D-GIWAXS techniques and also the free-charge carrier mobility via space-charge limited current theory. We obtained the result that, under such supersaturated conditions, co-solvents induce increased polymer crystalline aggregation into a 3D phase structure and boost charge-carrier transport characteristics. This provides a rational basis for the development of ideally-controlled BHJ films that yield efficient DT-PDPP2T-TT:PCBM solar cells. Therefore, carefully selecting solvent mixtures provides an approach toward efficient low bandgap polymer solar cells. (C) 2016 Elsevier B.V. All rights reserved.</P>

Self-correcting ensemble using a latent consensus model

Kim, N.,Son, Y.,Lee, Y.,Lee, J. Elsevier Science, B.V 2016 Applied soft computing Vol.47 No.-

<P>Ensemble is a widely used technique to improve the predictive performance of a learning method by using several competing expert systems. In this study, we propose a new ensemble combination scheme using a latent consensus function that relates each predictor to the other. The proposed method is designed to adapt and self-correct weights even when a number of expert systems malfunction and become corrupted. To compare the performance of the proposed method with existing methods, experiments are performed on simulated data with corrupted outputs as well as on real-world data sets. Results show that the proposed method is effective and it improves the predictive performance even when a number of individual classifiers are malfunctioning. (C) 2016 Elsevier B.V. All rights reserved.</P>

Effect of Cu content on the photovoltaic properties of wide bandgap CIGS thin-film solar cells prepared by single-stage process

Saifullah, M.,Moon, J.H.,Ahn, S.,Gwak, J.,Ahn, S.,Kim, K.,Eo, Y.J.,Yun, J.H. Elsevier 2016 Current Applied Physics Vol.16 No.11

<P>A solar cell based on Cu(In1-x,Ga-x)Se-2 (CIGS) with bandgap (E-g) of 1.5 eV is superior because of the low coefficient of power loss and resistive losses. CIGS thin-films with the E-g = 1.5 eV and Cu/(Ga + In) (CGI) ratios of 0.92, 0.84, and 0.78 were deposited in this study using single-stage process. Photovoltaic (PV) parameters of the solar cell ameliorated on raising CGI values from 0.78 to 0.84, but abruptly deteriorated on further increasing the CGI value to 0.92. The PV properties of CIGS solar cell with CGI = 0.92 were poor due to the high defect density and low shunt resistance. The optimal CGI range for making efficient wide gap CIGS solar cells through the single-stage process was found to be from -0.80 to 0.84. The best CIGS solar cell with CGI value of 0.84 exhibited the conversion efficiency of 11.00%. (C) 2016 Elsevier B.V. All rights reserved.</P>

Detection of drugs in 275 alcohol-positive blood samples of Korean drivers

Kim, E.,Choe, S.,Lee, J.,Jang, M.,Choi, H.,Chung, H. Elsevier Sequoia 2016 Forensic Science International Vol.265 No.-

<P>Since driving under the influence of drugs (DUID) is as dangerous as drink-driving, many countries regulate DUID by law. However, laws against the use of drugs while driving are not yet established in Korea. In order to investigate the type and frequency of drugs used by drivers in Korea, we analyzed controlled and non-controlled drugs in alcohol-positive blood samples. Total 275 blood samples were taken from Korean drivers, which were positive in roadside alcohol testing. The following analyses were performed: blood alcohol concentrations by GC; screening for controlled drugs by immunoassay and confirmation for positive samples by GC-MS. For the detection of DUID related drugs in blood samples, a total of 49 drugs were selected and were examined by GC-MS. For a rapid detection of these drugs, an automated identification software called 'DrugMan'' was used. Concentrations of alcohol in 275 blood samples ranged from 0.011 to 0.249% (average 0.119%). Six specimens showed positive results by immunoassay: one methamphetamine and five benzodiazepines I. By GC-MS confirmation, only benzodiazepines in four cases were identified, while methamphetamine and benzodiazepine in two cases were not detected from the presumptive positive blood samples. Using DrugMan, four drugs were detected; chlorpheniramine (5)*, diazepam (4), dextromethorphan (1) and doxylamine (1). In addition, ibuprofen (1), lidocaine (1) and topiramate (1) were also detected as general drugs in blood samples ('*' indicates frequency). The frequency of drug abuse by Korean drivers was relatively low and a total 14 cases were positive in 275 blood samples with a ratio of 5%. However it is necessary to analyze more samples including alcohol negative blood, and to expand the range of drug lists to get the detailed information. (C) 2016 Elsevier Ireland Ltd. All rights reserved.</P>