Intrinsic Electronic Structure and Nodeless Superconducting Gap of YBa2Cu3O7−δ\mathrm{YBa_{2} Cu_{3} O_{7-\delta} } Observed by Spatially-Resolved Laser-Based Angle Resolved Photoemission Spectroscopy

The spatially-resolved laser-based high resolution ARPES measurements have been performed on the optimally-doped $\mathrm{YBa_{2} Cu_{3} O_{7-\delta} }$ (Y123) superconductor. For the first time, we found the region from the cleaved surface that reveals clear bulk electronic properties. The intrinsic Fermi surface and band structures of Y123 are observed. The Fermi surface-dependent and momentum-dependent superconducting gap is determined which is nodeless and consistent with the d+is gap form

Orbital-Dependent Electron Correlation in Double-Layer Nickelate La3Ni2O7

The latest discovery of high temperature superconductivity near 80K in La3Ni2O7 under high pressure has attracted much attention. Many proposals are put forth to understand the origin of superconductivity. The determination of electronic structures is a prerequisite to establish theories to understand superconductivity in nickelates but is still lacking. Here we report our direct measurement of the electronic structures of La3Ni2O7 by high-resolution angle-resolved photoemmission spectroscopy. The Fermi surface and band structures of La3Ni2O7 are observed and compared with the band structure calculations. A flat band is formed from the Ni-3dz2 orbitals around the zone corner which is 50meV below the Fermi level. Strong electron correlations are revealed which are orbital- and momentum-dependent. Our observations will provide key information to understand the origin of high temperature superconductivity in La3Ni2O7.Comment: 18 pages, 4 figure

Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α

The conversion of skeletal muscle fiber from fast-twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Dietary garcinol significantly downregulated (p p p p p p p p p p < 0.05). Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes

Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α

The conversion of skeletal muscle fiber from fast-twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Dietary garcinol significantly downregulated (p &lt; 0.05) fast myosin heavy chain (MyHC) expression and upregulated (p &lt; 0.05) slow MyHC expression in the TA and soleus muscles. Garcinol significantly increased (p &lt; 0.05) the activity of peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) and markedly decreased (p &lt; 0.05) the acetylation of PGC-1α. In vitro and in vivo experiments showed that garcinol decreased (p &lt; 0.05) lactate dehydrogenase activity and increased (p &lt; 0.05) the activities of malate dehydrogenase and succinic dehydrogenase. In addition, the results of C2C12 myotubes showed that garcinol treatment increased (p &lt; 0.05) the transformation of glycolytic muscle fiber to oxidative muscle fiber by 45.9%. Garcinol treatment and p300 interference reduced (p &lt; 0.05) the expression of fast MyHC but increased (p &lt; 0.05) the expression of slow MyHC in vitro. Moreover, the acetylation of PGC-1α was significantly decreased (p &lt; 0.05). Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes

Synthesis, growth mechanism and thermal stability of copper nanoparticles encapsulated by multi-layer graphene

Copper nanoparticles encapsulated by multi-layer graphene have been produced in large quantity (in grams) by metal-organic chemical vapor deposition at 600 °C with copper(II) acetylacetonate powders as precursor. The obtained graphene/copper shell/core nanoparticles were found to be formed by a novel coalescence mechanism that is quite different from the well-known dissolution-precipitation mechanism for some other graphene/metal (such as nickel, iron or cobalt) shell/core nanoparticles. Differential scanning calorimetry and thermogravimetric analyses showed that the copper nanoparticles encapsulated by multi-layer graphene with a thickness of 1-2 nm were thermally stable up to 165 °C in air atmosphere. Moreover, high-resolution transmission electron microscopy showed that the single-crystal copper nanoparticles, after exposure to air for 60 days, did not exhibit any sign of oxidation

On the Completeness of Three-Dimensional Electron Diffraction Data for Structural Analysis of Metal-Organic Frameworks

Three-dimensional electron diffraction (3DED) has been proven as an effective and accurate method for structure determination of nano-sized crystals. In the past decade, the crystal structures of various new complex metal-organic frameworks (MOFs) have been revealed by 3DED, which has been the key to understand their properties. However, due to the design of transmission electron microscopes (TEMs), one drawback of 3DED experiments is the limited tilt range of goniometer, which often leads to incomplete 3DED data, particularly when the crystal symmetry is low. This drawback can be overcome by high throughput data collection using continuous rotation electron diffraction (cRED), where data from a large number of crystals can be collected and merged. Here, we investigate the effects of improving completeness on structural analysis of MOFs. We use ZIF-EC1, a zeolitic imidazolate framework (ZIF), as an example. ZIF-EC1 crystallizes in a monoclinic system with a plate-like morphology. cRED data of ZIF-EC1 with different completeness and resolution were analyzed. The data completeness increased to 92.0% by merging ten datasets. Although the structures could be solved from individual datasets with a completeness as low as 44.5% and refined to a high precession (better than 0.04 Å), we demonstrate that a high data completeness could improve the structural model, especially on the electrostatic potential map. We further discuss the strategy adopted during data merging. We also show that ZIF-EC1 doped with cobalt can act as an efficient electrocatalyst for oxygen reduction reaction. </p

A Chemoselective N‑Arylation Reaction of 2‑Aminopyridine Derivatives with Arynes

A chemoselective N-arylation reaction of 2-aminopyridine derivatives with arynes in good to excellent yields has been described. The N-arylation products could be further applied to the facile construction of benzoisoquinuclidines and isoquinuclidines as well as pyrido­[1,2-<i>a</i>]­benzimidazoles

Asymmetric Total Synthesis of (−)-Aspidophylline A

An asymmetric total synthesis of (−)-aspidophylline A has been accomplished. The key transformations include an asymmetric hydride transfer hydrogenation of an α,β-acetylenic ketone and a cationic gold­(I)-catalyzed 6-<i>exo-dig</i> cyclization involving an alkynylindole/aminal formation cascade, which enables stereoselective establishment of the requisite quaternary carbon center