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>

Structural, optical, and improved photocatalytic properties of CdS/SnO₂ hybrid photocatalyst nanostructure

Venkata Reddy, Ch.,Ravikumar, R.V.S.S.N.,Srinivas, G.,Shim, J.,Cho, M. Elsevier 2017 Materials science and engineering B. Advanced Func Vol.221 No.-

<P>CdS, SnO2 and CdS/SnO2 hybrid photocatalyst nanostructure were synthesized using a two-step (co-pre cipitation/hydrothermal) method. The as-prepared materials were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), surface analysis (BET), photoluminescence spectra (PL), UV-Vis diffusion reflectance spectroscopy (DRS), fourier transform infrared spectroscopy (FT-IR), and photocatalytic activity. The band gap energies calculated from the DRS results are 3.30, 2.15, and 2.99 eV for pristine SnO2, CdS, and the CdS/SnO2 hybrid photocatalyst, respectively. The CdS/SnO2 hybrid photocatalyst showed more efficient charge carrier separation and improved photocatalytic degradation of methyl orange (MO). The highest degradation rate constant was achieved for the CdS/SnO2 hybrid photocatalyst (0.02434 min(-1)) compared to CdS (0.01381 min(-1)) and SnO2 (0.00878 min(-1)). The present study provides insights for improving the photocatalytic activity and photo-stability of CdS/SnO2 hybrid photocatalyst. (C) 2017 Elsevier B.V. All rights reserved.</P>

CNT branching of three-dimensional steam-activated graphene hybrid frameworks for excellent rate and cyclic capabilities to store lithium ions

Park, Sul Ki,Choi, Kwangrok,Lee, Si-Hwa,Oh, Il-Kwon,Park, Sungjin,Park, Ho Seok Elsevier 2017 Carbon Vol.116 No.-

<P>The hierarchically architectured graphene-based materials are considered as a promising active or supporting material for the lithium ion batteries (LIBs). However, it faces critical challenges of the limited stored capacity, the mechanical brittleness, and the contact resistance. Herein, we demonstrate the unique hierarchical structures, where carbon nanotubes (CNTs) are branched onto the modified surfaces of three-dimensional (3D), steam-activated reduced graphene oxide (sRG-O) frameworks, prepared by self-assembly, steam activation, and microwave methods. The surface sites of 3D sRG-O are critical for controlling crystalline structure and deposition density of Fe3O4 nanoparticles through a microwave induced synthesis, as well as for providing a large surface area and conducting pathway. Simultaneously, the bamboo-like CNT branches are grown on the Fe3O4 nanoparticles acting as catalysts to stabilize and conductively connect 3D sRG-O/Fe interparticles for the enhanced rate and cyclic performances of LIB. Such a unique structure consisting of 1D nanostructure branched on the activated surface of 3D macroporous structure with decoration of OD nanoparticles provides high specific capacity of 1757 mAh g(-1) at 50 mA g(-1), good rate capability of 73.31% at 1000 mA g(-1), and gradual increase from 1490 to 2890 mAh g(-1) after 100 cycles. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Laser ignition and controlled explosion of nanoenergetic materials: The role of multi-walled carbon nanotubes

Kim, Ji Hoon,Cho, Myung Hoon,Kim, Kyung Ju,Kim, Soo Hyung Elsevier 2017 Carbon Vol.118 No.-

<P>Laser irradiation permits the remote ignition of nanoenergetic materials (nEMs). To reliably ignite nEMs with lower-power laser irradiation, light-sensitive materials could be added to the nEMs matrix. In this study, we investigated the effects of multi-walled carbon nanotubes (MWCNTs) on the combustion and explosion characteristics of laser irradiation-ignited nEMs. The threshold power and delay time of ignition gradually decreased with increases in the MWCNT contents of Al nanoparticle (NP)/CuO NP-based nEMs. The threshold power and delay time of MWCNT (10 wt%)/Al NP/CuO NP ignition were reduced to similar to 40% and similar to 50%, respectively, of those of MWCNT (10 wt%)/Al NP/CuO NP. This suggests that the MWCNTs act as effective optical igniters by absorbing irradiated laser beams and subsequently generating heat by the photo-thermal effect, promoting nEMs ignition. The optimal addition of <= 2 wt% MWCNTs in the nEMs matrix enhanced the pressurization rate, flame propagation speed, and pressure wave speed of nEMs because the MWCNTs rapidly transferred heat energy from nEMs combustion. However, adding excess MWCNTs suppressed the combustion and explosion characteristics of the Al NP/CuO NP-based nEMs matrix by heat dissipation and thermochemical interventions. This suggests that MWCNTs can potentially control the combustion and explosion characteristics of Al NP/CuO NP-based nEMs. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Annealing effect on plastic flow in nanocrystalline CoCrFeMnNi high-entropy alloy: A nanomechanical analysis

Lee, Dong-Hyun,Lee, Jung-A,Zhao, Yakai,Lu, Zhaoping,Suh, Jin-Yoo,Kim, Ju-Young,Ramamurty, Upadrasta,Kawasaki, Megumi,Langdon, Terence G.,Jang, Jae-il Elsevier 2017 ACTA MATERIALIA Vol.140 No.-

<P>The influence of annealing on the constitutive stress-strain response of nanocrystalline (nc) CoCrFeMnNi high-entropy alloy (HEA) was investigated through a series of nanoindentation experiments using five different three-sided pyramidal indenters. The nc HEA, produced by high-pressure torsion (HPT), was subjected to annealing at 450 degrees C for 1 and 10 h. Microstructural analysis using transmission electron microscopy (TEM) showed that three different nano-scale precipitates (NiMn-, FeCo-, and Co-rich phases) form in the primary single-phase matrix of nc HEA after annealing. The strain-dependent plastic flow response of nc HEA pre- and post-annealing was estimated using the indentation strain and constraint factor, revealing a significant strain softening in nc HEA, which becomes pronounced after annealing. TEM analysis of the deformed material underneath the indenter suggests that the plastic deformation aids in the dissolution of the annealing-induced intermetallic precipitates, which could be the mechanism for the pronounced softening. The dissolution mechanism was rationalized by the destabilization of precipitates during plastic deformation due to the increase in interface energy. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</P>

Iceberg Clique queries in large graphs

Hao, F.,Pei, Z.,Park, D.S.,Yang, L.T.,Jeong, Y.S.,Park, J.H. Elsevier Science Publishers 2017 Neurocomputing Vol.256 No.-

<P>This paper investigates the Iceberg Clique (IC) queries in a large graph, specially, given a user-specified threshold theta, an IC query reports the cliques where the number of vertices exceeds left perpendicular theta|V| right perpendicular. Toward this end, a practical IC query theorem is formally proposed and proved. With this proposed query theorem, a formal context and its corresponding iceberg concept lattice are first constructed from an input graph topology by Modified Adjacency Matrix; then, we prove that the IC queries problem is equivalent to finding the iceberg equiconcepts whose number of elements exceeds left perpendicular theta|V| right perpendicular. Theoretical analysis and experimental results demonstrate that the proposed query algorithm is feasible and efficient for finding the iceberg cliques from large graphs. (C) 2017 Published by Elsevier B.V.</P>

Evaluation of CO₂ injection in shale gas reservoirs with multi-component transport and geomechanical effects

Kim, Tae Hong,Cho, Jinhyung,Lee, Kun Sang ELSEVIER 2017 APPLIED ENERGY -BARKING THEN OXFORD- Vol.190 No.-

<P>Although research on CO2 injection in shale gas reservoirs has been focused for enhanced gas recovery (EGR) and CO2 storage, previous studies have not examined both multi-component transport and geomechanical effects. Therefore, this study presents new shale gas models for CO2 injection considering multi component adsorption, dissolution, molecular diffusion, and stress-dependerit compaction. Based on these mechanisms and data for Barnett shale field, a simulation model was constructed for CO2 flooding and huff and puff. The proposed model was used to examine the effects of CO2 injection to EGR and CO2 storage and various mechanisms. The results presented that CO2 flooding and huff and puff improve CH4 production by 24% and 6% respectively compared with rio injection scenario. At the end of simulated time, the injected CO2 is stored as free, adsorbed, and dissolved states in proportions of 42%, 55%, and 3% respectively. To confirm these results, Marcellus and New Albany shale models, which have different reservoir properties, are generated and compared with Barnett shale model. However, in Marcellus and New Albany shale models, effects of CO2 injection are lower than that of Barnett shale model. Therefore, to investigate factors affecting to the efficiency of CO2 injection in shale gas reServoirs, extensive simulations were performed. Results of the simulation analyses show that natural fracture permeability, hydraulic fracture half-length, well spacing, and Langmuir constants are significant factors for EGR and CO2 storage. For the real applications, these parameters should be mainly considered. The investigations performed in this study present better understanding of CO2 injection processes to EGR and CO2 storage and they are important for optimizing the designs of CO2 injection in field applications. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Population pharmacokinetics of moxifloxacin, cycloserine, p-aminosalicylic acid and kanamycin for the treatment of multi-drug-resistant tuberculosis

Chang, M.J.,Jin, B.,Chae, J.w.,Yun, H.y.,Kim, E.S.,Lee, Y.J.,Cho, Y.J.,Yoon, H.I.,Lee, C.T.,Park, K.U.,Song, J.,Lee, J.H.,Park, J.S. Elsevier Science Publishers ; Elsevier Science Pub 2017 INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS Vol.49 No.6

Control of multi-drug-resistant tuberculosis (MDR-TB) requires extensive, supervised chemotherapy because second-line anti-TB drugs have a narrower therapeutic range than first-line drugs. This study aimed to develop population pharmacokinetic (PK) models for second-line drugs in patients with MDR-TB, evaluate the recommended dosage regimens and, if necessary, suggest new dosage regimens. A prospective, single-centre PK study was performed on second-line anti-TB drugs in patients with MDR-TB. Moxifloxacin, cycloserine, p-aminosalicylic acid (PAS), kanamycin and other second-line drugs were administered to the patients. Plasma concentrations were analysed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Population PK models were developed using non-linear mixed effect modelling (NONMEM, Version 7.30; ICON Development Solutions, Ellicott City, MD, USA). Simulations were performed using the calculated PK parameters. The respective absorption rate constant, apparent clearance and apparent volume of distribution values were as follows: 0.305/h, 9.37@?L/h and 56.7@?L for moxifloxacin; 0.135/h, 1.38@?L/h and 10.5@?L for cycloserine; 0.510/h, 30.8@?L/h and 79.4@?L for PAS; and 1.67/h, 3.75@?L/h and 15.2@?L for kanamycin. The simulations showed that the following dosage regimens were more likely to be within the recommended concentration ranges than the raw data in this study: 200@?mg of moxifloxacin once daily (QD) (patient weight <50@?kg) and 400@?mg of moxifloxacin QD (patient weight ≥50@?kg), 500-750@?mg of cycloserine QD, 4.95-6.6@?g of PAS twice daily and 750-1000@?mg of intramuscular kanamycin QD. These findings indicate that the recommended doses should be revised to improve the clinical outcomes of MDR-TB treatment.

Effect of cryomilling on the high temperature creep properties of oxide dispersion strengthened steels

Gwon, J.H.,Kim, J.H.,Lee, K.A. Elsevier Sequoia 2016 Materials science & engineering. properties, micro Vol.676 No.-

<P>This study investigated the effect of cryomilling on the creep properties of oxide dispersion strengthened steels. Milling temperatures during mechanical alloying (MA) were set as room temperature and -150 degrees C to manufacture ODS ferritic steels, K1 (room temperature) and K4 (-150 degrees C) with Fe-14Cr-3W-0.4Ti-0.3Y(2)O(3) (wt%) composition. Microstructural observation identified large, inhomogeneous grains in 1<1 (700 nm), and a relatively fine, homogeneous grains in K4 (303 nm). Some grain boundaries featured secondary phases. The dispersion strengthened phase, fine oxide particles, was finer and more homogeneously distributed in K4 (7 nm) than in K1 (22 nm). A compressive creep test was performed at 650 degrees C. The steady-state creep rate in an identical stress range was lower in K4 than in K1. The stress exponent (n) was similar in the two alloys (n < 1) at low stress range, but at a higher stress range, K1 had a slightly higher stress exponent (n=3-4). Microstructural observation identified that dislocation creep is relatively well controlled in K4, and this is assumed to be due to the homogeneous, fine grain size, narrow inter-spacing among oxide particles and appropriate particle site. (C) 2016 Elsevier B.V. All rights reserved.</P>