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>

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>

Optimization of low frequency sound absorption by cell size control and multiscale poroacoustics modeling

Park, J.H.,Yang, S.H.,Lee, H.R.,Yu, C.B.,Pak, S.Y.,Oh, C.S.,Kang, Y.J.,Youn, J.R. Elsevier [etc.] 2017 Journal of Sound and Vibration Vol.397 No.-

<P>Sound absorption of a polyurethane (PU) foam was predicted for various geometries to fabricate the optimum microstructure of a sound absorbing foam. Multiscale numerical analysis for sound absorption was carried out by solving flow problems in representative unit cell (RUC) and the pressure acoustics equation using Johnson-Champoux-Allard (JCA) model. From the numerical analysis, theoretical optimum cell diameter for low frequency sound absorption was evaluated in the vicinity of 400 mu m under the condition of 2 cm 80 K (thickness of 2 cm and density of 80 kg/m(3)) foam. An ultrasonic foaming method was employed to modulate microcellular structure of PU foam. Mechanical activation was only employed to manipulate the internal structure of PU foam without any other treatment. A mean cell diameter of PU foam was gradually decreased with increase in the amplitude of ultrasonic waves. It was empirically found that the reduction of mean cell diameter induced by the ultrasonic wave enhances acoustic damping efficiency in low frequency ranges. Moreover, further analyses were performed with several acoustic evaluation factors; root mean square (RMS) values, noise reduction coefficients (NRC), and 1/3 octave band spectrograms. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Organic nonvolatile memory devices utilizing intrinsic charge-trapping phenomena in an n-type polymer semiconductor

Murari, N.M.,Hwang, Y.J.,Kim, F.S.,Jenekhe, S.A. Elsevier Science 2016 ORGANIC ELECTRONICS Vol.31 No.-

<P>Charge trapping is an undesirable phenomenon and a common challenge in the operation of n-channel organic field-effect transistors. Herein, we exploit charge trapping in an n-type semiconducting poly (naphthalene diimide-alt-biselenophene) (PNDIBS) as the key operational mechanism to develop high performance, nonvolatile, electronic memory devices. The PNDIBS-based field-effect transistor memory devices were programmed at 60 V and they showed excellent charge-trapping and de-trapping characteristics, which could be cycled more than 200 times with a current ratio of 10(3) between the two binary states. Programmed data could be retained for 10(3) s with a memory window of 28 V. This is a record performance for n-channel organic transistor with inherent charge-trapping capability without using external charge trapping agents. However, the memory device performance was greatly reduced, as expected, when the n-type polymer semiconductor was end-capped with phenyl groups to reduce the trap density. These results show that the trap density of n-type semiconducting polymers could be engineered to control the inherent charge-trapping capability and device performance for developing high-performance low-cost memory devices. (c) 2016 Elsevier B.V. All rights reserved.</P>

Superior pore network retention of carbon derived from naturally dried ginkgo leaves and its enhanced oxygen reduction performance

Razmjooei, F.,Singh, K.P.,Yu, J.S. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.260 No.-

<P>Obtaining a highly porous carbon has always been considered as an essential issue in many electrochemical applications. Ginkgo leaves have not only unique shape and color, but also interesting chemical and medical properties, which have inspired us to investigate them. In present approach, the naturally dried yellow ginkgo leaves, collected in autumn season, are directly used to prepare the porous carbon with simple two-step template-free procedure of pyrolysis at different temperatures followed by acid treatment for removal of inherent mineral salts. Interestingly, it is found that inherent salts present in the resulting carbon backbone can play as porogen to create high amount of pores in the carbon framework when the salts are removed by acid treatment. Effect of alternations in ginkgo leaves structure during the climate change, from spring to autumn, on ORR activity is examined for the first time on the carbons obtained by carbonizing different color, greenish and yellowish, ginkgo leaves at 1000 degrees C. Yellow leaves can maintain their original tissue structure during the gradual drying in cold weather of late fall, which results in formation of more stable structure, leading to development of much more pores and larger surface area in the resulting carbon. The unforeseen results exhibit surprisingly higher ORR activity for carbon catalyst obtained from yellow leaves (LY-1000) compared with one prepared from green leaves collected in summer, (LG-1000). Higher surface area of LY-1000 is found to be the most important key factor for its enhanced ORR activity. Furthermore, electrocatalytic property of the carbon greatly depends on the carbonization temperature, which is a crucial factor to make a balance between electrical conductivity, heteroatom doping and surface area. As the temperature increases, the heteroatom doping decreases, which is not favorable for ORR, but at the same time, the conductivity and surface area increase, which is beneficial for ORR, indicating intriguing trade-off between them as a function of temperature, which needs to be optimized for best ORR performance. Moreover, present work enables a large-scale production of efficient heteroatom-doped porous carbon from ginkgo leaf waste without using any activation and templating agents. (C) 2015 Elsevier B.V. All rights reserved.</P>

Fabrication and evaluation of capacitive silicon resonators with piezoresistive heat engines

Van Toan, N.,Van Nha, N.,Song, Y.,Ono, T. Elsevier Sequoia 2017 Sensors and actuators. A, Physical Vol.262 No.-

<P>This work reports the design, fabrication and evaluation of capacitive silicon resonators with piezoresistive heat engines. A combination of capacitive transduction and piezoresistive actuation based on a piezoresistive heat engine in the single micromechanical resonator is proposed to achieve a low insertion loss and small motional resistance. Capacitive silicon resonators with single and multiple piezoresistive beams have been demonstrated. In these structures, resonant bodies are divided into many parts that are connected to each other by using small piezoresistive beams to enhance electromechanical transductions by the piezoresistive heat engines. When a bias voltage V-b = 7 V is applied to the piezoresistive beams, the insertion loss and motional resistance of the capacitive silicon resonator with multiple piezoresistive beams are improved by 20 dB (enhanced from -68 dB to -48 dB) and 90% (reduced from 125.5 k Omega to 12.5 k Omega), respectively, in comparison to the case without a bias voltage. In addition, the tuning frequency characteristic with the piezoresistive effect is increased by 165 times over that of the structure with only the capacitive effect. (C) 2017 Elsevier B.V. All rights reserved.</P>

Label-free quantitative detection of nucleic acids based on surface-immobilized DNA intercalators

Lee, H.J.,Lee, S.S. Elsevier Sequoia 2017 Sensors and actuators. B, Chemical Vol.241 No.-

<P>We present a label-free biosensor for the detection of nucleic acids from PCR amplicons based on the surface plasmon resonance (SPR) with novel DNA intercalators. These intercalators can specifically bind to double-stranded DNA (ds-DNA), allowing ds-DNA to be quantitatively monitored by angle shifts of SPR following mass changes on the SPR sensor surface. Pyrenyl intercalator compounds that were synthesized consisted of pyrenyl groups as intercalating moieties, ethylene glycol hexamer linkers that resist non-specific binding events and thiol groups that formed self-assembled monolayers (SAMs) on a gold substrate. Also, hydroxyl group terminated compound instead of pyrenyl group was synthesized to ensure adequate separation between adjacent pyrene groups. The molar concentration ratio of mixed SAMs on SPR sensor surface was selected for maximum mass sensitivity on the basis of experimental results from various mixed ratios. Finally, we investigated the sensor responses due to intercalations on various concentrations of applied pure ds-DNA and demonstrated the capability for the analysis of PCR amplicons in the reaction product mixtures without any purification process. These results show that the proposed label-free biosensor devised based on strong binding interactions between DNA intercalators and base pairs of any ds-DNA can quantitatively analyze ds-DNA in accordance. (C) 2016 Elsevier B.V. All rights reserved.</P>

Cysteine ameliorates allergic inflammatory reactions by suppressing thymic stromal lymphopoietin production in activated human mast cells

Nam, Sun-Young,Kim, Hyung-Min,Jeong, Hyun-Ja Elsevier 2018 Nutrition research Vol.49 No.-

<P>Thymic stromal lymphopoietin (TSLP) derived by mast cells is recognized as a critical factor in many allergic inflammatory disorders. Cysteine is a well-known amino acid which exhibits anti-inflammatory activities. However, the effect and mechanism of cysteine on TSLP production have not been investigated. Thus, we hypothesized that cysteine may regulate TSLP production from mast cells. To test this hypothesis, the anti-inflammatory effects and signaling pathways of cysteine were investigated in phorbol 12-myristate 13-acetate 4 and calcium ionophore A23187 (PMACI)-stimulated human mast cell line HMC-1. Cysteine dramatically attenuated the levels of TSLP of both mRNA and protein without cytotoxicity. Moreover, cysteine suppressed caspase-1 activation and nuclear factor-kappa B translocation. The phosphorylation of p38 and c-Jun N-terminal kinase was downregulated in all cases in PMACI-stimulated HMC-1 cells treated with cysteine. In addition, cysteine decreased PMACI-induced proinflammatory cytokines in terms of both protein and mRNA levels. In conclusion, cysteine regulates TSLP production by blocking caspase-1, nuclear factor-kappa B, p38, and c-Jun N-terminal kinase-dependent pathways in activated HMC-1 cells, suggesting its potential as a regulator of allergic inflammatory diseases. (C) 2017 Elsevier Inc. All rights reserved.</P>

Comparison of IRI-2012 with JASON-1 TEC and incoherent scatter radar observations during the 2008-2009 solar minimum period

Ji, E.Y.,Jee, G.,Lee, C. Elsevier Science Ltd ; Pergamon 2016 Journal of Atmospheric and Solar-Terrestrial Physi Vol.146 No.-

<P>The 2008-2009 solar minimum period was unprecedentedly deep and extended. We compare the IRI-2012 with global TEC data from JASON-1 satellite and with electron density profiles observed from incoherent scatter radars (ISRs) at middle and high latitudes for this solar minimum period. Global daily mean TECs are calculated from JASON-1 TECs to compare with the corresponding IRI TECs during the 2008-2009 period. It is found that IRI underestimates the global daily mean TEC by about 20-50%. The comparison of global TEC maps further reveals that IRI overall underestimates TEC for the whole globe except for the low-latitude region around the equatorial anomaly, regardless of season. The underestimation is particularly strong in the nighttime winter hemisphere where the ionosphere seems to almost disappear in IRI. In the daytime equatorial region, however, the overestimation of IRI is mainly due to the misrepresentation of the equatorial anomaly in IRI. Further comparison with ISR electron density profiles confirms the significant underestimation of IRI at night in the winter hemisphere. (C) 2016 Elsevier Ltd. All rights reserved.</P>