Bifunctionally active and durable hierarchically porous transition metal-based hybrid electrocatalyst for rechargeable metal-air batteries

Seo, Min Ho,Park, Moon Gyu,Lee, Dong Un,Wang, Xiaolei,Ahn, Wook,Noh, Seung Hyo,Choi, Sung Mook,Cano, Zachary P.,Han, Byungchan,Chen, Zhongwei Elsevier 2018 Applied catalysis. B, Environmental Vol.239 No.-

<P><B>Abstract</B></P> <P>In this work, we show an effective strategy combining experimental and computational methods to explore and clarify rational design approaches utilizing transition metals for enhanced electrocatalysis of oxygen reactions. We report a bifunctional electrocatalyst synthesized by a chemical deposition of palladium (Pd) nanoparticles on three-dimensionally ordered mesoporous cobalt oxide (Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB>) demonstrating extreme stability and activity towards electrocatalytic oxygen reduction and evolution reactions (ORR and OER). Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> exhibits a significantly positive-shifted ORR half-wave potential of 0.88 V (vs. RHE) and a higher OER current density of 41.3 mA cm<SUP>−2</SUP> measured at 2.0 V (vs. RHE) relative to non-deposited 3DOM-Co<SUB>3</SUB>O<SUB>4</SUB>. Moreover, in terms of durability, Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> demonstrates a negligible half-wave potential loss with 99.5% retention during ORR and a high current density retention of 96.4% during OER after 1000 cycles of accelerated degradation testing (ADT). <I>Ab-initio</I> computational simulation of the oxygen reactions reveals that the modification of the electronic structure by combining Pd and Co<SUB>3</SUB>O<SUB>4</SUB> lowers the Pd d-band center and enhances the electron abundance at the Fermi level, resulting in improved kinetics and conductivity. Furthermore, it is elucidated that the enhanced electrochemical stability is attributed to an elevated carbon corrosion potential (<I>U<SUB>corr,C</SUB> </I>) for the Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> surface and an increased dissolution potential (U<SUB>diss</SUB>) of Pd nanoparticles. Meanwhile, synergistic improvements in the bifunctional activity resulting from the combination of Pd and 3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> were confirmed by both electrochemical and physical characterization methods, which highlights the practical viability of Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> as an efficient bifunctional catalyst for rechargeable metal-air batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Strategy for rational design of transition metal-based bifunctional electrocatalyst. </LI> <LI> Synergistic combination of Pd and 3DOM Co<SUB>3</SUB>O<SUB>4</SUB> for enhanced activity and durability. </LI> <LI> Doped-Pd on 3DOM Co<SUB>3</SUB>O<SUB>4</SUB> leads to electron abundance at the Fermi level. </LI> <LI> Low carbon corrosion and bulk–like dissolution tendency of doped-Pd on 3DOM Co<SUB>3</SUB>O<SUB>4</SUB>. </LI> <LI> 500 h of Zn-air battery operation with improved charge-discharge performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stc1: A Critical Link between RNAi and Chromatin Modification Required for Heterochromatin Integrity

Bayne, Elizabeth H.,White, Sharon A.,Kagansky, Alexander,Bijos, Dominika A.,Sanchez-Pulido, Luis,Hoe, Kwang-Lae,Kim, Dong-Uk,Park, Han-Oh,Ponting, Chris P.,Rappsilber, Juri,Allshire, Robin C. Cell Press 2010 Cell Vol.140 No.5

<P><B>Summary</B></P><P>In fission yeast, RNAi directs heterochromatin formation at centromeres, telomeres, and the mating type locus. Noncoding RNAs transcribed from repeat elements generate siRNAs that are incorporated into the Argonaute-containing RITS complex and direct it to nascent homologous transcripts. This leads to recruitment of the CLRC complex, including the histone methyltransferase Clr4, promoting H3K9 methylation and heterochromatin formation. A key question is what mediates the recruitment of Clr4/CLRC to transcript-bound RITS. We have identified a LIM domain protein, Stc1, that is required for centromeric heterochromatin integrity. Our analyses show that Stc1 is specifically required to establish H3K9 methylation via RNAi, and interacts both with the RNAi effector Ago1, and with the chromatin-modifying CLRC complex. Moreover, tethering Stc1 to a euchromatic locus is sufficient to induce silencing and heterochromatin formation independently of RNAi. We conclude that Stc1 associates with RITS on centromeric transcripts and recruits CLRC, thereby coupling RNAi to chromatin modification.</P>

Effect of pulsed electric current on dissolution of Mg₁₇Al₁₂ phases in as-extruded AZ91 magnesium alloy

Jeong, Hye-Jin,Kim, Moon-Jo,Park, Ju-Won,Yim, Chang Dong,Kim, Jae Joong,Kwon, Oh Duck,Madakashira, Phaniraj P.,Han, Heung Nam Elsevier 2017 Materials science & engineering. properties, micro Vol.684 No.-

<P><B>Abstract</B></P> <P>In this study, the tensile deformation behavior of as-extruded AZ91 magnesium alloy under pulsed electric current has been investigated based on microstructural observations. The flow stress decreased and the elongation increased remarkably on applying electric current in comparison with non-pulsed tensile test at both room temperature and at 70°C. The results of EBSD and EDS analysis showed that dissolution of the Mg<SUB>17</SUB>Al<SUB>12</SUB> phase obviously occurs during pulsed tensile test due to thermal effect caused by Joule heating and athermal effect of electric current. To distinguish the athermal and thermal effects of electric current, the induction heat treatment (IHT) that follows the temperature cycle measured during pulsed tensile test was carried out using a dilatometer, which could control the temperature of specimen by an induction heater in a vacuum. Additionally, electropulsing treatment (EPT) was conducted and compared with the conventional heat treatment (CHT) under the same condition. The fraction of Mg<SUB>17</SUB>Al<SUB>12</SUB> phase after pulsed tensile test and EPT was obviously lower in comparison with IHT and CHT, respectively. The results prove that applying electric current accelerates dissolution of Mg<SUB>17</SUB>Al<SUB>12</SUB> phase in as-extruded AZ91 alloy with a distinct effect from Joule heating during deformation. It is proposed that electrically-assisted manufacturing (EAM) technique can improve the efficiency of forming process for as-extruded AZ91 alloy.</P>

OGLE-2005-BLG-018: CHARACTERIZATION OF FULL PHYSICAL AND ORBITAL PARAMETERS OF A GRAVITATIONAL BINARY LENS

Shin, I.-G.,Udalski, A.,Han, C.,Gould, A.,Dominik, M.,Fouqué,, P.,Kubiak, M.,Szymań,ski, M. K.,Pietrzyń,ki, G.,Soszyń,ski, I.,Ulaczyk, K.,Wyrzykowski, Ł.,DePoy, D. L.,Dong, S.,Gau IOP Publishing 2011 The Astrophysical journal Vol.735 No.2

<P>We present the result of the analysis of the gravitational binary-lensing event OGLE-2005-BLG-018. The light curve of the event is characterized by two adjacent strong features and a single weak feature separated from the strong features. The light curve exhibits noticeable deviations from the best-fit model based on standard binary parameters. To explain the deviation, we test models including various higher-order effects of the motions of the observer, source, and lens. From this, we find that it is necessary to account for the orbital motion of the lens in describing the light curve. From modeling the light curve considering the parallax effect and Keplerian orbital motion, we are able to not only measure the physical parameters but also to find a complete orbital solution of the lens system. It is found that the event was produced by a binary lens located in the Galactic bulge with a distance of 6.7 +/- 0.3 kpc from the Earth. The individual lens components with masses 0.9 +/- 0.3 M-circle dot and 0.5 +/- 0.1 M-circle dot are separated with a semi-major axis of a = 2.5 +/- 1.0 AU and orbiting each other with a period P = 3.1 +/- 1.3 yr. This event demonstrates that it is possible to extract detailed information about binary lens systems from well-resolved lensing light curves.</P>

The effect of barrier layer-mediated catalytic deactivation in vertically aligned carbon nanotube growth

Patole, S P,Yu, Seong-Man,Shin, Dong-Wook,Kim, Ha-Jin,Han, In-Taek,Kwon, Kee-Won,Yoo, Ji-Beom Institute of Physics [etc.] 2010 Journal of Physics. D, Applied Physics Vol.43 No.9

<P>The effect of Al-barrier layer-mediated Fe-catalytic deactivation in vertically aligned carbon nanotube (CNT) growth was studied. The substrate surface morphology, catalytic diffusion and barrier layer oxidation were found to be dependent on the annealing temperature of the barrier layer, which ultimately affects CNT growth. The annealed barrier layer without complete oxidation was found to be suitable for top to bottom super aligned CNT arrays. The highest average CNT growth rate of up to 3.88 µm s<SUP>−1</SUP> was observed using this simple approach. Details of the analysis are also presented.</P>

A SUB-SATURN MASS PLANET, MOA-2009-BLG-319Lb

Miyake, N.,Sumi, T.,Dong, Subo,Street, R.,Mancini, L.,Gould, A.,Bennett, D. P.,Tsapras, Y.,Yee, J. C.,Albrow, M. D.,Bond, I. A.,Fouqué,, P.,Browne, P.,Han, C.,Snodgrass, C.,Finet, F.,Furusawa, K IOP Publishing 2011 The Astrophysical journal Vol.728 No.2

<P>We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K-or M-dwarf star in the inner Galactic disk or Galactic bulge. The high-cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high-magnification event approximately 24 hr prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 +/- 0.02) x 10(-4) and a separation of d = 0.97537 +/- 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t(E), and angular Einstein radius,theta(E), along with a standard Galactic model indicates a host star mass of M-L = 0.38(-0.18)(+0.34) M-circle dot and a planet mass of M-p = 50(-24)(+44)M(circle plus), which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4(-0.6)(+1.2) AU and a distance to the planetary system of D-L = 6.1(-1.2)(+1.1) kpc. This separation is similar to 2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing.</P>

MOA 2010-BLG-477Lb: CONSTRAINING THE MASS OF A MICROLENSING PLANET FROM MICROLENSING PARALLAX, ORBITAL MOTION, AND DETECTION OF BLENDED LIGHT

Bachelet, E.,Shin, I.-G.,Han, C.,Fouqué,, P.,Gould, A.,Menzies, J. W.,Beaulieu, J.-P.,Bennett, D. P.,Bond, I. A.,Dong, Subo,Heyrovský,, D.,Marquette, J.-B.,Marshall, J.,Skowron, J.,Street, IOP Publishing 2012 The Astrophysical journal Vol.754 No.1

<P>Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA 2010-BLG-477. The measured planet-star mass ratio is q = (2.181 +/- 0.004) x 10(-3) and the projected separation is s = 1.1228 +/- 0.0006 in units of the Einstein radius. The angular Einstein radius is unusually large theta(E) = 1.38 +/- 0.11 mas. Combining this measurement with constraints on the 'microlens parallax' and the lens flux, we can only limit the host mass to the range 0.13 < M/M-circle dot < 1.0. In this particular case, the strong degeneracy between microlensing parallax and planet orbital motion prevents us from measuring more accurate host and planet masses. However, we find that adding Bayesian priors from two effects (Galactic model and Keplerian orbit) each independently favors the upper end of this mass range, yielding star and planet masses of M-* = 0.67(-0.13)(+0.33) M-circle dot and m(p) = 1.5(-0.3)(+0.8) M-JUP at a distance of D = 2.3 +/- 0.6 kpc, and with a semi-major axis of a = 2(-1)(+3) AU. Finally, we show that the lens mass can be determined from future high-resolution near-IR adaptive optics observations independently from two effects, photometric and astrometric.</P>

Plasma Diffusion Along a Fine Tube Positive Column

Guangsup Cho,Jung-Hyun Kim,Jong-Mun Jeong,Ha-Chung Hwang,Dong-Jun Jin,Je-Huan Koo,Eun-Ha Choi,Verboncoeur, J.P.,Han-Sup Uhm IEEE 2009 IEEE transactions on plasma science Vol.37 No.3

<P>The propagation velocity of light emission is observed to be u<SUB>p</SUB> ~0.92 times10<SUP>+5</SUP> m/s along a tube of an inner diameter r<SUB>o</SUB> ~1.5 times10<SUP>-3</SUP> m with an external electrode fluorescent lamp filled with 97% Ne and 3% Ar at a total pressure of 30 torr, a mercury-free lamp without phosphor coating the inside glass wall. The origin of this propagation is shown to be ambipolar diffusion with a plasma diffusion speed of u<SUB>p</SUB> ~ (4.8/r<SUB>o</SUB>)D<SUB>a</SUB> for diffusion coefficient D<SUB>a</SUB> along the positive column. When a high voltage magnitude is applied at the external electrode, a high-density plasma is generated inside the hollow electrode, and the plasma diffuses along the positive column toward the ground electrode.</P>

CHARACTERIZING LENSES AND LENSED STARS OF HIGH-MAGNIFICATION SINGLE-LENS GRAVITATIONAL MICROLENSING EVENTS WITH LENSES PASSING OVER SOURCE STARS

Choi, J.-Y.,Shin, I.-G.,Park, S.-Y.,Han, C.,Gould, A.,Sumi, T.,Udalski, A.,Beaulieu, J.-P.,Street, R.,Dominik, M.,Allen, W.,Almeida, L. A.,Bos, M.,Christie, G. W.,Depoy, D. L.,Dong, S.,Drummond, J.,Ga IOP Publishing 2012 The Astrophysical journal Vol.751 No.1

<P>We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of theta(E) similar to 0.08 mas combined with the short timescale of t(E) similar to 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of similar to 0.84M(circle dot) is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.</P>

Adiponectin Regulates Bone Marrow Mesenchymal Stem Cell Niche Through a Unique Signal Transduction Pathway: An Approach for Treating Bone Disease in Diabetes : Adiponectin Regulates BMSC Niche

Yu, Liming,Tu, Qisheng,Han, Qianqian,Zhang, Lan,Sui, Lei,Zheng, Leilei,Meng, Shu,Tang, Yin,Xuan, Dongying,Zhang, Jin,Murray, Dana,Shen, Qingping,Cheng, Jessica,Kim, Sung-Hoon,Dong, Lily Q.,Valverde, P Wiley (John WileySons) 2015 Stem Cells Vol.33 No.1

<P>Adiponectin (APN) is an adipocyte-secreted adipokine that exerts well-characterized antidiabetic properties. Patients with type 2 diabetes (T2D) are characterized by reduced APN levels in circulation and impaired stem cell and progenitor cell mobilization from the bone marrow for tissue repair and remodeling. In this study, we found that APN regulates the mobilization and recruitment of bone marrow-derived mesenchymal stem cells (BMSCs) to participate in tissue repair and regeneration. APN facilitated BMSCs migrating from the bone marrow into the circulation to regenerate bone by regulating stromal cell-derived factor (SDF)-1 in a mouse bone defect model. More importantly, we found that systemic APN infusion ameliorated diabetic mobilopathy of BMSCs, lowered glucose concentration, and promoted bone regeneration in diet-induced obesity mice. In vitro studies allowed us to identify Smad1/5/8 as a novel signaling mediator of APN receptor (AdipoR)-1 in BMSCs and osteoblasts. APN stimulation of MC3T3-E1 osteoblastic cells led to Smad1/5/8 phosphorylation and nuclear localization and increased SDF1 mRNA expression. Although APN-mediated phosphorylation of Smad1/5/8 occurred independently from adaptor protein, phosphotyrosine interaction, pleckstrin homology domain, and leucine zipper containing 1, it correlated with the disassembly of protein kinase casein kinase 2 and AdipoR1 in immunoprecipitation experiments. Taken together, this study identified APN as a regulator of BMSCs migration in response to bone injury. Therefore, our findings suggest APN signaling could be a potential therapeutic target to improve bone regeneration and homeostasis, especially in obese and T2D patients.</P>