Comparison of Anatomical Parameters of the Parotid Gland Between Two Groups.

<p>Comparison of Anatomical Parameters of the Parotid Gland Between Two Groups.</p

Unidirectional Thermal Diffusion in Bimetallic Cu@Au Nanoparticles

Understanding the atomic diffusions at the nanoscale is important for controlling the synthesis and utilization of nanomaterials. Here, using <i>in situ</i> X-ray absorption spectroscopy coupled with theoretical calculations, we demonstrate a so far unexplored unidirectional diffusion from the Au shell to the Cu core in thermally alloying Cu@Au core@shell architecture of <i>ca.</i> 7.1 nm. The initial diffusion step at 423 K is found to be characterized by the formation of a diffusion layer composed of a Au-dilute substitutional CuAu-like intermetallic compound with short Cu–Au bond length (2.61 Å). The diffusion further happens by the migration of the Au atoms with large disorder into the interior Cu matrix at higher temperatures (453 and 553 K). These results suggest that the structural preference of a CuAu-like compound, along with the nanosized effect, plays a critical role in determining the atomic diffusion dynamics

Vacancy-Induced Ferromagnetism of MoS₂ Nanosheets

Outstanding magnetic properties are highly desired for two-dimensional ultrathin semiconductor nanosheets. Here, we propose a phase incorporation strategy to induce robust room-temperature ferromagnetism in a nonmagnetic MoS₂ semiconductor. A two-step hydrothermal method was used to intentionally introduce sulfur vacancies in a 2H-MoS₂ ultrathin nanosheet host, which prompts the transformation of the surrounding 2H-MoS₂ local lattice into a trigonal (1T-MoS₂) phase. 25% 1T-MoS₂ phase incorporation in 2H-MoS₂ nanosheets can enhance the electron carrier concentration by an order, introduce a Mo⁴⁺ 4d energy state within the bandgap, and create a robust intrinsic ferromagnetic response of 0.25 μ_B/Mo by the exchange interactions between sulfur vacancy and the Mo⁴⁺ 4d bandgap state at room temperature. This design opens up new possibility for effective manipulation of exchange interactions in two-dimensional nanostructures

Strong Surface Hydrophilicity in Co-Based Electrocatalysts for Water Oxidation

Developing efficient and durable oxygen evolution electrocatalyst is of paramount importance for the large-scale supply of renewable energy sources. Herein, we report the design of significant surface hydrophilicity based on cobalt oxyhydroxide (CoOOH) nanosheets to greatly improve the surface hydroxyl species adsorption and reaction kinetics at the Helmholtz double layer for high-efficiency water oxidation activity. The as-designed CoOOH-graphene nanosheets achieve a small surface water contact angle of ∼23° and a large double-layer capacitance (<i>C</i>_dl) of 8.44 mF/cm² and thus could evidently strengthen surface species adsorption and trigger electrochemical oxygen evolution reaction (OER) under a quite low onset potential of 200 mV with an excellent Tafel slope of 32 mV/dec. X-ray absorption spectroscopy and first-principles calculations demonstrate that the strong interface electron coupling between CoOOH and graphene extracts partial electrons from the active sties and increases the electron state density around the Fermi level and effectively promotes the surface intermediates formation for efficient OER

Graphene Activating Room-Temperature Ferromagnetic Exchange in Cobalt-Doped ZnO Dilute Magnetic Semiconductor Quantum Dots

Control over the magnetic interactions in dilute magnetic semiconductor quantum dots (DMSQDs) is a key issue to future development of nanometer-sized integrated “spintronic” devices. However, manipulating the magnetic coupling between impurity ions in DMSQDs remains a great challenge because of the intrinsic quantum confinement effects and self-purification of the quantum dots. Here, we propose a hybrid structure to achieve room-temperature ferromagnetic interactions in DMSQDs, <i>via</i> engineering the density and nature of the energy states at the Fermi level. This idea has been applied to Co-doped ZnO DMSQDs where the growth of a reduced graphene oxide shell around the Zn_0.98Co_0.02O core turns the magnetic interactions from paramagnetic to ferromagnetic at room temperature, due to the hybridization of 2p_<i>z</i> orbitals of graphene and 3d obitals of Co²⁺–oxygen-vacancy complexes. This design may open up a kind of possibility for manipulating the magnetism of doped oxide nanostructures

Half-Unit-Cell α‑Fe₂O₃ Semiconductor Nanosheets with Intrinsic and Robust Ferromagnetism

The synthesis of atomically thin transition-metal oxide nanosheets as a conceptually new class of materials is significant for the development of next-generation electronic and magnetic nanodevices but remains a fundamental chemical and physical challenge. Here, based on a “template-assisted oriented growth” strategy, we successfully synthesized half-unit-cell nanosheets of a typical transition-metal oxide α-Fe₂O₃ that show robust intrinsic ferro­magnetism of 0.6 μ_B/atom at 100 K and remain ferromagnetic at room temperature. A unique surface structure distortion, as revealed by X-ray absorption spectroscopy, produces nonidentical Fe ion environments and induces distance fluctuation of Fe ion chains. First-principles calculations reveal that the efficient breaking of the quantum degeneracy of Fe 3d energy states activates ferro­magnetic exchange interaction in these Fe_5‑co–O–Fe_6‑co ion chains. These results provide a solid design principle for tailoring the spin-exchange interactions and offer promise for future semi­conductor spin­tronics

Fast Photoelectron Transfer in (C_ring)–C₃N₄ Plane Heterostructural Nanosheets for Overall Water Splitting

Direct and efficient photocatalytic water splitting is critical for sustainable conversion and storage of renewable solar energy. Here, we propose a conceptual design of two-dimensional C₃N₄-based in-plane heterostructure to achieve fast spatial transfer of photoexcited electrons for realizing highly efficient and spontaneous overall water splitting. This unique plane heterostructural carbon ring (C_ring)–C₃N₄ nanosheet can synchronously expedite electron–hole pair separation and promote photoelectron transport through the local in-plane π-conjugated electric field, synergistically elongating the photocarrier diffusion length and lifetime by 10 times relative to those achieved with pristine g-C₃N₄. As a result, the in-plane (C_ring)–C₃N₄ heterostructure could efficiently split pure water under light irradiation with prominent H₂ production rate up to 371 μmol g^–1 h^–1 and a notable quantum yield of 5% at 420 nm