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>

Effects of temperature-induced stress on the structural, electrical, and optical properties of ZnO:Ga thin films grown on Si substrates

Hwang, Younghun,Park, Seungmin,Kang, Manil,Um, Youngho Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.1

Crystalline ZnO:Ga thin films with highly preferential c-axis oriented crystals were prepared on Si(001) substrates at different temperatures using the reactive magnetron sputtering technique. Effects of temperature-induced stress in ZnO:Ga films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), electrical transport, and spectroscopic ellipsometry measurements. XRD results showed that the films were highly c-axis (out-of-plane) oriented and crystallinity improved with growth temperature. The residual compressive stress in films grown at low temperature relaxes with substrate temperature and becomes tensile stress with further increases in growth temperature. Resistivity of the films decreases with increasing stress, while the carrier concentration and mobility increase as the stress increases. The mechanism of the stress-dependent bandgap of ZnO:Ga films grown at different temperatures is suggested in the present work. (C) 2013 Elsevier B.V. All rights reserved.

Constitutive equations optimized for determining strengths of metallic alloys

Kang, Seung-Kyun,Kim, Young-Cheon,Kim, Kug-Hwan,Kwon, Dongil,Kim, Ju-Young Elsevier 2014 Mechanics of materials Vol.73 No.-

We investigate compatibilities of three constitutive equations, the Hollomon, the Swift, and the Voce equations for determination of yield and ultimate tensile strengths based on tensile true stress-strain curves of 27 metal alloys including those with power-law type and linear-type strain-hardening. We analyze each constitutive equation in terms of yield strength determined by the intercept of the linear elastic loading curve and plastic flow curve and ultimate tensile strength evaluated by the concept of instability in tension. We found that the describing plastic flow is very sensitive in determination of the yield strength and tensile strength from parameters of constitutive equation. Voce equation gives estimate yield strength and tensile strength better than Hollomon and Swift equations. (C) 2014 Elsevier Ltd. All rights reserved.

Preferential oxidation of CO in a hydrogen-rich stream over Au/MO_x/Al₂O₃ (M=La, Ce, and Mg) catalysts

Lakshmanan, P.,Park, J.E.,Kim, B.,Park, E.D. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-

<P>The preferential oxidation of CO (CO-PROX) under excess hydrogen over Au/MOx/Al2O3 (M = La, Ce, and Mg) catalysts was investigated. All catalysts were prepared by a deposition-precipitation method with urea and characterized with inductively coupled plasma-atomic emission spectroscopy, N-2 physisorption, temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy. The catalytic activity of the supported gold catalysts was found to be dependent on the promoter, and decreased in the order: Au/La2O3/Al2O3 > Au/CeO2/Al2O3 > Au/MgO/Al2O3 > Au/Al2O3. The catalytic activity of the Au/La2O3/Al2O3 catalyst depended on the pretreatment conditions, i.e., reduction with aqueous NaBH4, thermal reduction with H-2, and calcination with O-2. This indicates that the oxidation state of gold is an important factor in the activity of the catalyst, and that metallic gold is more suitable than its oxidized form for this reaction. XPS results revealed that the treatment with aqueous NaBH4 resulted in more negative charge in gold particles than that of conventional thermal reduction under H-2. Smaller gold particles appeared to be favorable for the low-temperature CO-PROX activity of the Au/La2O3/Al2O3 catalysts, which showed stable CO-PROX performance, even in the presence of CO2. (C) 2015 Elsevier B.V. All rights reserved.</P>

Designs and CFD analyses of H₂SO₄ and HI thermal decomposers for a semi-pilot scale SI hydrogen production test facility

Shin, Youngjoon,Lim, Jihong,Lee, Taehoon,Lee, Kiyoung,Jo, Changkeun,Kim, Minhwan ELSEVIER 2017 APPLIED ENERGY -BARKING THEN OXFORD- Vol.204 No.-

<P>Based on our previous study on the experimental performance tests of the catalyst-packed type HI thermal decomposer and bayonet type H2SO4 thermal decomposer for a 50 NL-H-2/h SI test facility, which were directly heated using electrical heating chambers, semi-pilot scale H2SO4 and HI decomposers for the 1 N m(3)-H-2/h SI test facility coupled to an out-of-pile helium loop have been designed, and it was theoretically confirmed that the design specifications satisfy the hydrogen production capacity based on a Computational Fluid Dynamics (CFD) analysis. The effects of the overall heat transfer coefficient on the helium outlet temperatures and decomposition percentages of the decomposers were identified. The H2SO4 and HI decomposers proposed are capable of outlet helium temperatures of 734 degrees C and 383 degrees C for an overall heat transfer coefficient of 5 W/m(2) K, respectively, which satisfy the operating temperature conditions of the out-of-pile helium loop. The average thermal decomposition percentages of the proposed decomposers are 60.4% for sulfuric acid and 22.4% for hydrogen iodide. These decomposition percentages obtained from the numerical results are acceptable with a hydrogen production rate of 1 N m(3)-H-2/h. Modification points of the decomposers to increase the decomposition percentages are suggested, such as a minimization of heat loss into the atmosphere and optimization of component designs. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Application of Ca-doped mesoporous silica to well-grouting cement for enhancement of self-healing capacity

Lee, S.W.,Jo, M.,Kim, J.W.,Kim, T. Elsevier Ltd 2016 Materials & Design Vol.89 No.-

<P>Carbonation has been considered as an alternative to prevent CO2 leakage. In this study, calcium-doped mesoporous silica (CDMS) was introduced into Portland cement as a promoter of carbonation. An admixture of CDMS and American Petroleum Institute (API) Class G Portland cement exposed to CO2-saturated water was analyzed under geologic sequestration conditions (40 degrees C and 80 MPa) to assess the carbonation properties and self-healing effect of CDMS for CO2 storage. The capacity of CDMS to synthesize CaCO3 from CO2 via carbonation was identified in an in vitro crystallization test. Analysis of the cut surface of a cement core showed the rapid synthesis of CaCO3 including calcite and aragonite. Rietveld analysis was employed for quantitative phase analysis. The quantitative analysis of the cement carbonation showed that tricalcium silicate (C3S) and dicalcium silicate (C2S) play important roles in cement carbonation. Several crystal phases of CaCO3 were identified in this study including calcite, aragonite and amorphous CaCO3. X-ray diffractometry (XRD), a field emission-scanning electron microscope (FE-SEM) equipped with an energy dispersive X-ray spectrometer (EDS), Si-29 MAS-NMR (magic angle spinning-nuclear magnetic resonance) spectrometry, thermogravimetiy-differential thermal analysis (TG-DTA) and FT-IR (Fourier transform infrared spectroscopy) were applied to characterize the admixture. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Selective cation depletion from an ionic liquid droplet under an electric field

Ahn, Myung Mo,Yang, Yu Dong,Im, Do Jin,Oh, Jung Min,Kang, In Seok Elsevier 2017 Journal of molecular liquids Vol.244 No.-

<P>We conducted MD simulation to investigate the general electrohydrodynamic behavior of droplets of imidazolium-based ionic liquids composed of 1-ethyl-3-methylimidazolium (EMIM) anion and either his(trifluoromethylsulfonyl)imide (NTf2) or ethylsulfate (ES) cation. The cation depletion phenomena observed in the previous work [J.Phys. Chem. Lett. 5 3021 (2014)] is analyzed in detail to clarify its mechanism. Shape deformation due to electric stress and the ion distributions inside the droplet are calculated with 200 ion pairs and the intermolecular interactions between ions are directly analyzed. Together with an analytical interpretation of the conducting droplet in an electric field, we show that the MD simulation successfully explains the mechanism of selective ion depletion of an ionic liquid droplet in an electric field, and the retreating motion of the droplet observed by experiments. (C) 2017 Elsevier B.V. All rights reserved.</P>

Associations between building characteristics and children's allergic symptoms - A cross-sectional study on child's health and home in Seoul, South Korea

Choi, Jieun,Chun, Chungyoon,Sun, Yuexia,Choi, Yoorim,Kwon, Suhyun,Bornehag, C.G.,Sundell, Jan Elsevier 2014 Building and environment Vol.75 No.-

A cross-sectional study on the home environment and asthma and allergy in children was carried out among children 1-8 years old in Seoul, South Korea from 2009 to 2010. Questionnaires were distributed to 5107 parents through daycare centers and kindergartens; 2755 parents responded, a response rate of 54%. Seven percent and 23% of children were reported to have doctor-diagnosed asthma and hay fever, respectively. A majority (57%) of the families reported having PVC flooring in child's or parents' bedroom. More than 96% of homes used a floor heating system. PVC was used more often as a floor covering in single family houses than in apartments (67% vs. 49%, p < 0.001). PVC flooring was significantly associated with eczema in the previous 6 months (AOR 1.54,95% Cl 1.13-2.09) when adjusted for gender, age, family allergy, socioeconomic status and environmental tobacco smoke. Older buildings tended to have dampness problems, and, consequently, were positively correlated with the prevalence of wheeze. Floor moisture significantly increased the association between PVC and symptoms of wheezing (AOR 2.57, 95% Cl 1.36-4.82) and eczema (AOR 1.97, 95% Cl 1.18-3.28). Apartments without mechanical ventilation in bedrooms were associated with a slight increase in asthma and allergy among children. This study suggests that building characteristics and home exposure can partly explain recent increases in asthma and allergy among children in Seoul. (c) 2014 Elsevier Ltd. All rights reserved.

Formation mechanism of typical onion ring structures and void defects in friction stir lap welded dissimilar aluminum alloys

Yoon, T.J.,Yun, J.G.,Kang, C.Y. Elsevier Ltd 2016 Materials & Design Vol.90 No.-

<P>The formation mechanism for typical onion ring structure and void defect with heat input during FSLW was continuously visualized by an exit-hole continuous observation technique. Based on this result, the compatibility between microstructure, microtexture, element maps and strain maps using electron backscattered diffraction (EBSD) with the chemical indexing assisted by EDS analysis was simultaneously investigated. The results revealed that the threaded probe was significantly correlated to typical onion ring structure and the onion structure formed as soon as it touched the probe. This result is different from the results so far. On the other hand, the remnant of original interface between top and bottom plates after FSLW and asymmetrical flow around rotating tool were significantly correlated to the formation of void defect in low heat input condition. (C) 2015 Elsevier Ltd. All rights reserved.</P>