Hydrogen atoms can provide high phonon frequencies and strong electron-phonon coupling in hydrogen-rich materials, which are believed to be potential high-temperature superconductors at lower ...pressure than metallic hydrogen. Especially, recently both of theoretical and experimental reports on sulfur hydrides under pressure exhibiting superconductivity at temperatures as high as 200 K have further stimulated an intense search for room-temperature superconductors in hydrides. This review focuses on crystal structures, stabilities, pressure-induced transformations, metallization, and superconductivity of hydrogen-rich materials at high pressures.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
Elucidating the synergistic catalytic mechanism between multiple active centers is of great significance for heterogeneous catalysis; however, finding the corresponding experimental evidence ...remains challenging owing to the complexity of catalyst structures and interface environment. Here we construct an asymmetric TeN
2
–CuN
3
double-atomic site catalyst, which is analyzed via full-range synchrotron pair distribution function. In electrochemical CO
2
reduction, the catalyst features a synergistic mechanism with the double-atomic site activating two key molecules: operando spectroscopy confirms that the Te center activates CO
2
, and the Cu center helps to dissociate H
2
O. The experimental and theoretical results reveal that the TeN
2
–CuN
3
could cooperatively lower the energy barriers for the rate-determining step, promoting proton transfer kinetics. Therefore, the TeN
2
–CuN
3
displays a broad potential range with high CO selectivity, improved kinetics and good stability. This work presents synthesis and characterization strategies for double-atomic site catalysts, and experimentally unveils the underpinning mechanism of synergistic catalysis.
Apelin receptor (APJR) is a key regulator of human cardiovascular function and is activated by two different endogenous peptide ligands, apelin and Elabela, each with different isoforms diversified ...by length and amino acid sequence. Here we report the 2.6-Å resolution crystal structure of human APJR in complex with a designed 17-amino-acid apelin mimetic peptide agonist. The structure reveals that the peptide agonist adopts a lactam constrained curved two-site ligand binding mode. Combined with mutation analysis and molecular dynamics simulations with apelin-13 binding to the wild-type APJR, this structure provides a mechanistic understanding of apelin recognition and binding specificity. Comparison of this structure with that of other peptide receptors suggests that endogenous peptide ligands with a high degree of conformational flexibility may bind and modulate the receptors via a similar two-site binding mechanism.
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•Designed peptide mimic AMG3054 with reduced conformational flexibility•Structure of apelin receptor in complex with AMG3054•Designed peptide AMG3054 adopts a lactam constrained curved structure•A two-site binding mode is observed for peptide GPCR recognition
Ma et al. present an atomic-resolution structure of the human apelin receptor (APJR, a class A G-protein-coupled receptor) in complex with a 17-residue apelin peptide mimic by X-ray crystallography. This structure reveals a two-site ligand binding mode that has not been seen in any other solved class A receptor structures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Lipid droplets are cellular organelles that consists of a neutral lipid core covered by a monolayer of phospholipids and many proteins. They are thought to function in the storage, transport, and ...metabolism of lipids, in signaling, and as a specialized microenvironment for metabolism in most types of cells from prokaryotic to eukaryotic organisms. Lipid droplets have received a lot of attention in the last 10 years as they are linked to the progression of many metabolic diseases and hold great potential for the development of neutral lipid-derived products, such as biofuels, food supplements, hormones, and medicines. Proteomic analysis of lipid droplets has yielded a comprehensive catalog of lipid droplet proteins, shedding light on the function of this organelle and providing evidence that its function is conserved from bacteria to man. This review summarizes many of the proteomic studies on lipid droplets from a wide range of organisms, providing an evolutionary perspective on this organelle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Dynamic recrystallization (DRX) associated with different second-phases in Mg94.5Y2Gd1Zn2Mn0.5 alloy during hot extrusion was investigated. Discontinuous DRX occurred along the interface of MgZn2(Y, ...Gd) particle and 18R LPSO phase while continuous DRX emerged in the kink bands of 14H LPSO phase. Moreover, two DRX processes enhanced the strength and ductility.
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IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SBCE, SBJE, UPUK
Invigorated by the high temperature superconductivity in some binary hydrogen-dominated compounds, we systematically explored high-pressure phase diagrams and superconductivity of a ternary Mg-Ge-H ...system using ab initio methods. Stoichiometric MgGeH6 with high hydrogen content exhibiting Pm3combining macron symmetry was predicted from a series of high-pressure synthesis paths. We performed an in-depth study on three distinct formation routes to MgGeH6, i.e., Mg + Ge + 3H2 → MgGeH6, MgGe + 3H2 → MgGeH6 and MgH2 + GeH4 → MgGeH6 at high pressures. By directly squeezing three elemental solids Mg + Ge + 3H2, we obtained ternary MgGeH6 at 200 GPa. By adding a little bit of the MgGe alloy into hydrogen, we found that MgGeH6 can form and stabilize at about 200 GPa. More intriguingly, upon compressing MgH2 and GeH4 to 250 GPa, we also predicted the same MgGeH6. Electron structure calculations reveal that the cubic MgGeH6 is a good metal and takes on ionic character. Electron-phonon coupling calculation reveals a large λ = 1.16 for MgGeH6 at 200 GPa. In particular, we found that ternary MgGeH6 could be a potential high temperature superconductor with a superconducting transition temperature Tc of ∼67 K at 200 GPa.
Stretchable conductive composites play a pivotal role in the development of personalized electronic devices, electronic skins, and artificial implant devices. This article explores the fabrication ...and characterization of stretchable composites based on natural rubber (NR) filled with molybdenum disilicide (MoSi2) nanoparticles and multi-walled carbon nanotubes (MWCNTs). Experimental characterization and molecular dynamics (MD) simulations are employed to investigate the static and dynamic properties of the composites, including morphology, glass transition temperature (Tg), electrical conductivity, and mechanical behavior. Results show that the addition of MoSi2 nanoparticles enhances the dispersion of MWCNTs within the NR matrix, optimizing the formation of a conductive network. Dynamic mechanical analysis (DMA) confirms the Tg reduction with the addition of MWCNTs and the influence of MoSi2 content on Tg. Mechanical testing reveals that the tensile strength increases with MoSi2 content, with an optimal ratio of 4:1 MoSi2:MWCNTs. Electrical conductivity measurements demonstrate that the MoSi2/MWCNTs/NR composites exhibit enhanced conductivity, reaching optimal values at specific filler ratios. MD simulations further support experimental findings, highlighting the role of MoSi2 in improving dispersion and mechanical properties. Overall, the study elucidates the synergistic effects of nanoparticles and nanotubes in enhancing the properties of stretchable conductive composites.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Superconducting flywheels have potential application value in aerospace field, and its suspension time is a key factor. Alternating Current (AC) loss associated with rotation is an important ...parameter that affects the suspension time, so it is very important to study how to reduce the AC loss. Recently, a method of preparing YBa2Cu3O7−x (YBCO) high-temperature superconducting flywheels by Direct-Ink-Writing (DIW) 3D printing was developed. In this paper, the circular hole superconducting flywheel prepared by this method is optimized by the idea of structural optimization. Based on the finite element method, the AC loss before and after optimization is calculated and analyzed. It is found that the elliptical holes make the superconducting flywheel have lower AC loss than circular holes, with a reduction of 58.49%. Then, the YBCO superconducting flywheel with an optimized elliptical structure was prepared by the DIW 3D printing method. The magnetic levitation experiment found that the levitation time of the optimized superconducting flywheel was increased to 162 s compared with the previous 120 s under the same conditions, and the optimized structure had a higher levitation mass ratio. It provides theoretical and experimental support for reducing the AC loss of superconductors by applying the idea of structural optimization design in engineering practice.
Much effort has been invested in the investigation of the structural basis of G protein-coupled receptors (GPCRs) activation. Inverse agonists, which can inhibit GPCRs with constitutive activity, are ...considered useful therapeutic agents, but the molecular mechanism of such ligands remains insufficiently understood. Here, we report a crystal structure of the ghrelin receptor bound to the inverse agonist PF-05190457 and a cryo-electron microscopy structure of the active ghrelin receptor-Go complex bound to the endogenous agonist ghrelin. Our structures reveal a distinct binding mode of the inverse agonist PF-05190457 in the ghrelin receptor, different from the binding mode of agonists and neutral antagonists. Combining the structural comparisons and cellular function assays, we find that a polar network and a notable hydrophobic cluster are required for receptor activation and constitutive activity. Together, our study provides insights into the detailed mechanism of ghrelin receptor binding to agonists and inverse agonists, and paves the way to design specific ligands targeting ghrelin receptors.
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