1,873 research outputs found

    Electroneutrality Breakdown and Specific Ion Effects in Nanoconfined Aqueous Electrolytes Observed by NMR

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    Ion distribution in aqueous electrolytes near the interface plays critical roles in electrochemical, biological and colloidal systems and is expected to be particularly significant inside nanoconfined regions. Electroneutrality of the total charge inside nanoconfined regions is commonly assumed a priori in solving ion distribution of aqueous electrolytes nanoconfined by uncharged hydrophobic surfaces with no direct experimental validation. Here, we use a quantitative nuclear magnetic resonance approach to investigate the properties of aqueous electrolytes nanoconfined in graphitic-like nanoporous carbon. Substantial electroneutrality breakdown in nanoconfined regions and very asymmetric responses of cations and anions to the charging of nanoconfining surfaces are observed. The electroneutrality breakdown is shown to depend strongly on the propensity of anions toward the water-carbon interface and such ion-specific response follows generally the anion ranking of the Hofmeister series. The experimental observations are further supported by numerical evaluation using the generalized Poisson-Boltzmann equationComment: 26 pages, 3 figure

    A study on the correlation between poles and cuts in ππ\pi\pi scattering

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    In this paper we propose a dispersive method to describe two-body scattering with unitarity imposed. This approach is applied to elastic ππ\pi\pi scattering. The amplitudes keep single-channel unitarity and describe the experimental data well, and the low-energy amplitudes are consistent with that of chiral perturbation theory. The pole locations of the σ\sigma, f0(980)f_0(980), ρ(770)\rho(770) and f2(1270)f_2(1270) and their couplings to ππ\pi\pi are obtained. A virtual state appearing in the isospin-two S-wave is confirmed. The correlations between the left (and right) hand cut and the poles are discussed. Our results show that the poles are more sensitive to the right hand cut rather than the left hand cut. The proposed method could be used to study other two-body scattering processes.Comment: 10 pages, 4 figure

    Semileptonic BB and BsB_s decays involving scalar and axial-vector mesons

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    We report our theoretical calculations on the branching fractions for the semileptonic BB and BsB_s decays, i.e., B(Bs)(P,V,S,A)νB (B_s) \to (P,\, V,\, S,\,A) \ell \nu_\ell, where PP and VV denote the pseudoscalar and vector mesons, respectively, while SS denotes the scalar meson with mass above 1 GeV and AA the axial-vector meson. The branching fractions for the semileptonic BPB\to P and VV modes have been measured very well in experiment and our theoretical values are in good agreement with them. The ones for BSB\to S and AA modes are our theoretical predictions. There is little experimental information on the semileptonic BsB_s decays although much theoretical effort has been done. In addition, we predict the branching fractions of BD0(2400)νˉB\to D^*_0(2400) \ell \bar\nu_\ell and BsDs0(2317)νˉB_s\to D^{*-}_{s0}(2317) \ell \bar\nu_\ell as (2.31±0.25)×103(2.31\pm 0.25)\times 10^{-3} and (3.07±0.34)×103(3.07\pm0.34)\times 10^{-3}, in order, assuming them as the conventional mesons with quark-antiquark configuration. The high luminosity e+ee^+e^- collider SuperKEKB/Belle-II is running, with the data sample enhanced by a factor of 40 compared to Belle, which will provide huge opportunity for the test of the theoretical predictions and further help understand the inner structure of these scalar and axial vector mesons, e.g., the glueball content of f0(1710)f_0(1710) and the mixing angles for the axial-vector mesons. These decay channels can also be accessed by the LHCb experiment.Comment: final version, will appear in EPJC, one more reference adde

    Combined analysis of endometrial thickness and pattern in predicting outcome of in vitro fertilization and embryo transfer: a retrospective cohort study

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    <p>Abstract</p> <p>Objective</p> <p>To evaluate the combined effect of endometrial thickness and pattern on clinical outcome in patients undergoing in vitro fertilization/intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET).</p> <p>Methods</p> <p>Cycles of IVF/ICSI-ET conducted between January 2003 and December 2008 at a university-based reproductive center were reviewed retrospectively. Endometrial ultrasonographic characteristics were recorded on the day of hCG administration. In the combined analysis, endometrial thickness groups (group 1: equal or <7 mm; group 2: 7-14 mm; group 3: >14 mm) were subdivided into two endometrial patterns (pattern A: triple-line; pattern B: no-triple line). Clinical pregnancy rate (CPR) and early miscarriage rate in different groups were analyzed.</p> <p>Results</p> <p>A total of 2896 cycles were reviewed. Clinical pregnancy rate (CPR) was 24.4% in group1-A. There were no second trimester pregnancies in group 1-B. Miscarriage rate in group 2-A was significantly lower compared to group 2-B (P < 0.01), although CPR did not show any significant differences between the groups. A no-triple line endometrial pattern with moderate endometrial thickness (7-14 mm) had a detrimental effect on pregnancy outcome, but not the occurrence of pregnancy. In group 3, there was no difference in CPR and miscarriage rates between the two patterns; adequate endometrial thickness (>14 mm) seemed to mitigate the detrimental impact (high miscarriage rate) of pattern B.</p> <p>Conclusion</p> <p>Combined analysis of endometrial thickness and pattern on the day of hCG administration was a better predictor of the outcome of IVF/ICSI-ET and may be more helpful for patient counseling than the separate analyses.</p

    Cardiac resynchronization therapy (CRT) with right ventricular sense triggered left ventricular pacing benefits for the hemodynamics compared with standard CRT for chronic congestive heart failure: A cross-over study

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    Background: The aim of this study was to investigate the effect of cardiac resynchronization therapy (CRT) with right ventricular (RV) sense triggered left ventricular (LV) pacing for chronic heart failure (CHF). Methods: Thirty patients who were eligible for the Class I indication of CRT were enrolled and the informed consents were signed. Left ventricular ejection fraction (LVEF), diastolic mitral flow velocity time integral (VTI), mitral regurgitation flow VTI, and aortic valve flow VTI were measured with GE Vivid 7 (GE Medical, Milwaukee, WI, USA) before and after CRT. The echocardiographic measurements and the average annual costs of the device use were compared. Results: The duration of QRS complex, the length of time used for optimization, and the average annual cost of the device use under RV sense triggered LV pacing were significantly less than that under standard biventricular (BiV) pacing (p &lt; 0.01), while the average battery lifetime was longer. Subgroup analysis showed that LVEF, diastolic mitral flow VTI, and aortic valve flow VTI under RV sense triggered LV pacing were greater than that under standard BiV pacing with right or LV pre-activation. The average battery lifetime was significantly longer and the average annual cost of the device use was less. The mitral regurgitation flow VTI under RV sense triggered LV pacing was less than that under standard BiV pacing with RV pre-activation. Conclusions: RV sense triggered LV provides benefits for CHF patients over standard CRT in terms of maintaining the physiological atrio-ventricular delay of atrio-ventricular node and improving the acute hemodynamic effects

    Structure and Magnetotransport Properties of Epitaxial Nanocomposite La0.67Ca0.33MnO3:SrTiO3 Thin Films Grown by a Chemical Solution Approach

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    Epitaxial La0.67Ca0.33MnO3:SrTiO3 (LCMO:STO) composite thin films have been grown on single crystal LaAlO3(001) substrates by a cost effective polymer-assisted deposition method. Both x-ray diffraction and high-resolution transmission electron microscopy confirm the growth of epitaxial films with an epitaxial relationship between the films and the substrates as (002)film||(002)sub and [202]film||[202]sub. The transport property measurement shows that the STO phase significantly increases the resistivity and enhances the magnetoresistance (MR) effect of LCMO and moves the metal-insulator transition to lower temperatures. For example, the MR values measured at magnetic fields of 0 and 3 T are −44.6% at 255 K for LCMO, −94.2% at 125 K for LCMO:3% STO, and −99.4% at 100 K for LCMO:5% STO, respectively

    Structure and Magnetotransport Properties of Epitaxial Nanocomposite La0.67Ca0.33MnO3:SrTiO3 Thin Films Grown by a Chemical Solution Approach

    Get PDF
    Epitaxial La0.67Ca0.33MnO3:SrTiO3 (LCMO:STO) composite thin films have been grown on single crystal LaAlO3(001) substrates by a cost effective polymer-assisted deposition method. Both x-ray diffraction and high-resolution transmission electron microscopy confirm the growth of epitaxial films with an epitaxial relationship between the films and the substrates as (002)film||(002)sub and [202]film||[202]sub. The transport property measurement shows that the STO phase significantly increases the resistivity and enhances the magnetoresistance (MR) effect of LCMO and moves the metal-insulator transition to lower temperatures. For example, the MR values measured at magnetic fields of 0 and 3 T are −44.6% at 255 K for LCMO, −94.2% at 125 K for LCMO:3% STO, and −99.4% at 100 K for LCMO:5% STO, respectively
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