Two-dimensional (2D) conductive metal-organic frameworks (MOFs), whose advanced electrical properties accompany their intrinsic structural characteristics, represent an exciting new class of 2D atomic crystals for the van der Waals integration of novel heterostructures and the development of novel nano/ quantum devices. Guided by topology, we report two 2D MOFs (1 and 2) constructed via combination of [In(COO) 4 ] À metal nodes and tetratopic tetrathiafulvalene (TTF)-based linkers, with ultrahigh proton conductivity (6.66 3 10 À4 and 1.30 3 10 À2 S cm À1 for 1 and 2, respectively). Additionally, high electrical conductivity was simultaneously achieved with the pure protonic nature of the 2D MOF 2. The electrical conduction at the MOF-metal interface is enabled by the redox-switchable behavior of the TTF-based ligands. This unique charge-transport mechanism, protonic/pseudo-capacitance coupling, offers a new strategy for utilizing the ionic conductivity from MOFs to construct functional electronic devices.

The development of cell therapy for repairing damaged or diseased skeletal muscle has been hindered by the inability to significantly expand immature, transplantable myogenic stem cells (MuSCs) in culture. To overcome this limitation, a deeper understanding of the mechanisms regulating the transition between activated, proliferating MuSCs and differentiation-primed, poorly engrafting progenitors is needed. Here, we show that methyltransferase Setd7 facilitates such transition by regulating the nuclear accumulation of β-catenin in proliferating MuSCs. Genetic or pharmacological inhibition of Setd7 promotes in vitro expansion of MuSCs and increases the yield of primary myogenic cell cultures. Upon transplantation, both mouse and human MuSCs expanded with a Setd7 small-molecule inhibitor are better able to repopulate the satellite cell niche, and treated mouse MuSCs show enhanced therapeutic potential in preclinical models of muscular dystrophy. Thus, Setd7 inhibition may help bypass a key obstacle in the translation of cell therapy for muscle disease.

Two new antimony sulfate chlorides named (NH4)2SbCl­(SO4)2 and (NH4)­SbCl2(SO4) were successfully synthesized through solvent-free synthesis method. (NH4)2SbCl­(SO4)2 exhibits a three-dimensional framework constructed of [SbCl­(SO4)2]2– chains and NH4 + ions. And the NH4 + cations play the role of charge balance and provide the hydrogen bond constructed with oxygen atoms. (NH4)­SbCl2(SO4) shows a two-dimensional layer structure that is composed of the regularly stacked [SbCl2(SO4)]− chains via hydrogen-bonding interactions. Both of the titled compounds possess the same chemical composition and the similar Sb–Cl–SO4 chains, while hydrogen-bonding interactions and lone-pair cations play the synergistic effect on the framework structures and macroscopic centricities resulting in that the (NH4)2SbCl­(SO4)2 is centrosymmetric and the (NH4)­SbCl2(SO4) is non-centrosymmetric (NCS). Powder second harmonic generation (SHG) measurements indicated that the NCS compound (NH4)­SbCl2(SO4) is type I phase-matchable and exhibits SHG responses of ∼1.7 times that of KH2PO4.

On the edge of the bandgap in a fiber Bragg grating (FBG) narrow peaks of high transmission exist at frequencies where light interferes constructively in the forward direction. In the vicinity of these transmission peaks, light reflects back and forth numerous times across the periodic structure and experiences a large group delay. Since the sensitivity of a phase sensor to most external perturbations is proportional to the reciprocal of group velocity, in these slow-light regions the sensitivity of an FBG is expected to be significantly enhanced over traditional FBG sensors operated around the Bragg wavelength. In this paper, we describe means of producing and operating FBGs that support structural slow light with a group index that can be in principle as high as several thousand. We present simulations elucidating how to select the FBG parameters, in particular index modulation, length, and apodization, to generate such low group velocities, and quantify the very large improvement in strain and temperature sensitivities resulting from these new slow-light configurations. As a proof of concept, we report an FBG with a group index of 127, or a group velocity of 2 360 km s. This is by far the lowest group velocity reported to date in an FBG. Used as a strain sensor, this slow-light FBG is shown to be able to detect a strain as small as 880 f Hz, the lowest value reported for a passive FBG sensor.

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We report the extraordinary enhanced transmission of microwaves through a subwavelength metallic mesh sandwiched between two identical split-ring arrays. Such split-rings/metallic mesh/ split-rings structure demonstrates some unique electromagnetic ͑EM͒ characteristics. It is found that the transmittances of EM wave are significantly enhanced at some frequencies near the stop bands of the split rings. The theoretical simulation indicates that two different physical mechanisms dominate those transmissions: negative refractive index effect and electromagnetic wave tunneling when EM wave penetrates through negative permittivity media sandwiched between two high permittivity slabs.

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