Nucleation-Induced Self-Assembly of Multiferroic BiFeO₃–CoFe₂O₄ Nanocomposites

Large areas of perfectly ordered magnetic CoFe₂O₄ nanopillars embedded in a ferroelectric BiFeO₃ matrix were successfully fabricated via a novel nucleation-induced self-assembly process. The nucleation centers of the magnetic pillars are induced before the growth of the composite structure using anodic aluminum oxide (AAO) and lithography-defined gold membranes as hard mask. High structural quality and good functional properties were obtained. Magneto-capacitance data revealed extremely low losses and magneto-electric coupling of about 0.9 μC/cmOe. The present fabrication process might be relevant for inducing ordering in systems based on phase separation, as the nucleation and growth is a rather general feature of these systems

Yellow Luminescence of Polar and Nonpolar GaN Nanowires on <i>r</i>‑Plane Sapphire by Metal Organic Chemical Vapor Deposition

We have grown horizontal oriented, high growth rate, well-aligned polar (0001) single crystalline GaN nanowires and high-density and highly aligned GaN nonpolar (11–20) nanowires on <i>r</i>-plane substrates by metal organic chemical vapor deposition. It can be found that the polar nanowires showed a strong yellow luminescence (YL) intensity compared with the nonpolar nanowires. The different trends of the incorporation of carbon in the polar, nonpolar, and semipolar GaN associated with the atom bonding structure were discussed and proved by energy-dispersive X-ray spectroscopy, suggesting that C-involved defects are the origin responsible for the YL in GaN nanowires

Microcrystalline-Induced Physical-Cross-linking toward a High Performance Hyper-Branched Anion Exchange Membrane

An anion exchange membrane (AEM) is the core component of the low-cost anion exchange membrane fuel cell (AEMFC). To realize the commercial application of AEMFC, extremely low swelling of AEM is vital for the membrane electrode assembly preparation and cell integrity, except for high hydroxide conductivity, strength, and chemical stability. However, it is hard to achieve an extremely low swelling ratio while maintaining high conductivity, especially for a homogeneous membrane. Herein, a series of quaternized poly­(trans-1,2-diphenylethylene-co-terphenyl-N,N′-dimethyl piperidinium) with a sophisticated structure are synthesized for AEM to address such dilemma. The physical-cross-linking induced by microcrystalline effectively restricts the swelling of AEM (<6.2%@80 °C). Moreover, a hyper-branched structure is also introduced in order to increase the free volume in the polymer membrane, resulting in a high conductivity of up to 275.6 mS cm–1 at 80 °C. Accordingly, excellent fuel cell performance with a peak power density of 1.13 W cm–2 for H2–O2 at 80 °C is attained

Pharmacologic Approach to Defective Protein Trafficking in the E637K-hERG Mutant with PD-118057 and Thapsigargin

<div><p>Background</p><p>Treatment of LQT2 is inadequate. Many drugs which can pharmacologically rescue defective protein trafficking in LQT2 also result in potent blockade of HERG current, negating their therapeutic benefit. It is reported that PD-118057 and thapsigargin can rescue LQT2 without hERG channel blockade, but the precise mechanism of action is unknown. Furthermore, the effect of PD-118057 and thapsigargin on the dominant negative E637K-hERG mutant has not been previously investigated.</p><p>Objective</p><p>In this study, we investigated: (a) the effect of PD-118057 and thapsigargin on the current amplitudes of WT-hERG and WT/E637K-hERG channels; (b) the effect of PD-118057 and thapsigargin on the biophysical properties of WT-hERG and WT/E637K-hERG channels; (c) whether drug treatment can rescue channel processing and trafficking defects of the WT/E637K-hERG mutant.</p><p>Methods</p><p>The whole-cell Patch-clamp technique was used to assess the effect of PD-118057 and thapsigargin on the electrophysiological characteristics of the rapidly activating delayed rectifier K⁺ current (I_kr) of the hERG protein channel. Western blot was done to investigate pharmacological rescue on hERG protein channel function.</p><p>Results</p><p>In our study, PD-118057 was shown to significantly enhance both the maximum current amplitude and tail current amplitude, but did not alter the gating and kinetic properties of the WT-hERG channel, with the exception of accelerating steady-state inactivation. Additionally, thapsigargin shows a similar result as PD-118057 for the WT-hERG channel, but with the exception of attenuating steady-state inactivation. However, for the WT/E637K-hERG channel, PD-118057 had no effect on either the current or on the gating and kinetic properties. Furthermore, thapsigargin treatment did not alter the current or the gating and kinetic properties of the WT/E637K-hERG channel, with the exception of opening at more positive voltages.</p><p>Conclusion</p><p>Our findings illustrate that neither PD-118057 nor thapsigargin play a role in correcting the dominant-negative effect of the E637K-hERG mutant.</p></div

Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on deactivation of hERG channel.

<p>Insert shows the voltage clamp protocol. a-d: Representative deactivation traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG in the presence or absence of PD-118057 and thapsigargin (arrow marks the deactivation phase). e: Fast and slow components of deactivation time constants (tau, τ) are plotted as a function of test potentials for WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).</p

Analysis of hERG protein expression in HEK293 cells.

<p>a. Representative protein expression of untreated WT-hERG, WT/E637K-hERG, and E637K-hERG channels. b–d. Representative protein expression of WT-hERG, WT/E637K-hERG and E637K-hERG channels treated with 1 uM thapsigargin for 24 h to 48 h, respectively. Thapsigargin has no effect on the protein expression profile of either WT/E637K-hERG or E637K-hERG. e–f. Representative protein expression of WT-hERG, WT/E637K-hERG and E637K-hERG channels treated with 3 µM PD-118057 for 24 h to 48 h, respectively. As demonstrated, PD-118057 also has no effect on the protein expression profile of either WT/E637K-hERG or E637K-hERG channels.</p

Flexible Quasi-Two-Dimensional CoFe₂O₄ Epitaxial Thin Films for Continuous Strain Tuning of Magnetic Properties

Epitaxial thin films of CoFe₂O₄ (CFO) have successfully been transferred from a SrTiO₃ substrate onto a flexible polyimide substrate. By bending the flexible polyimide, different levels of uniaxial strain are continuously introduced into the CFO epitaxial thin films. Unlike traditional epitaxial strain induced by substrates, the strain from bending will not suffer from critical thickness limitation, crystalline quality variation, and substrate clamping, and more importantly, it provides a more intrinsic and reliable way to study strain-controlled behaviors in functional oxide systems. It is found that both the saturation magnetization and coercivity of the transferred films can be changed over the bending status and show a high accord with the movement of the curvature bending radius of the polyimide substrate. This reveals that the mechanical strain plays a critical role in tuning the magnetic properties of CFO thin films parallel and perpendicular to the film plane direction

Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on steady-state inactivation of hERG channel.

<p>Inset shows the voltage clamp protocol. a-d: Representative current traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of PD-118057 and thapsigargin. e: Normalized steady-state inactivation curves in cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).</p

Effect of PD-118057 (3 µM) on voltage-dependent activation of hERG channel.

<p>Inset shows the voltage clamp protocol. a-f: Representative current traces in HEK293 cells transfected with WT-hERG, WT/E637K-hERG, and E637K-hERG in the presence or absence of PD-118057. g, h: Current-voltage (I-V) relationships for peak and tail current amplitudes of WT-hERG and WT/E637K-hERG transfected cells in the presence and absence of PD-118057. i: Amplitudes of tail currents of WT-hERG and WT/E637K-hERG channels in the presence or absence of PD-119057 are plotted as a function of the test potential and fitted to a Boltzmann function (n = 6).</p

Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on recovery from inactivation of hERG channel.

<p>Insert shows the voltage clamp protocol. a-d: Representative recovery from inactivation traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of PD-118057 and thapsigargin. e: Time constants (tau, τ) for hERG channel recovery from inactivation are plotted as a function of test voltages for WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).</p