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The emergence of superconductivity in two-dimensional (2D) materials has attracted tremendous research efforts because the origins and mechanisms behind the unexpected and fascinating superconducting phenomena remain unclear. In particular, the superconductivity can survive in 2D systems even with weakened disorder and broken spatial inversion symmetry. Here, structural and superconducting transitions of 2D van der Waals (vdW) hydrogenated germanene (GeH) are observed under compression and decompression processes. GeH possesses a superconducting transition with a critical temperature (Tc) of 5.41 K at 8.39 GPa. A crystalline to amorphous transition occurs at 16.80 GPa, while superconductivity remains. An abnormal increase of Tc up to 6.11 K was observed during the decompression process, while the GeH remained in the 2D amorphous phase. A combination study of in situ high-pressure synchrotron X-ray diffraction, in situ high-pressure Raman spectroscopy, transition electron microscopy, and density functional theory simulations suggests that the superconductivity in 2D vdW GeH is attributed to the increased density of states at the Fermi level as well as the enhanced electron-phonon coupling effect under high pressure even in the form of an amorphous phase. The unique pressure-induced phase transition of GeH from 2D crystalline to 2D amorphous metal hydride provides a promising platform to study the mechanisms of amorphous hydride superconductivity.
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Ancient Chinese sauce glaze porcelain has recently received growing attention for the discovery of epsilon iron oxide (ε-Fe2O3) crystals in glaze. In this work, we first confirm the presence of ε-Fe2O3 microcrystals, in large quantiteis, in sauce glaze porcelain fired at the Qilizhen kiln in Jiangxi province during the Southern Song dynasty. We then employed focused ion beam scanning electron microscopy (FIB-SEM) to investigate the three-dimensional microstructure of ε-Fe2O3 microcrystals, which revealed three well-separated layers (labeled, respectively, as LY1, LY2, and LY3 from the glaze surface to inside) under the glaze surface. Specifically, LY1 consists of well-defined dendritic fractal structure with high ordered branches at micrometers scale, LY2 has spherical or irregular-shaped particles at nanometers scale, while LY3 consists of dendrites with four, six, or eight primary branches ranging from several nanometers to around 1 µm. Given these findings, we proposed a process for the possible growth of ε-Fe2O3 microcrystals in ancient Chinese sauce glaze.
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Bioenergetic therapy is emerging as a promising therapeutic approach. However, its therapeutic effectiveness is restricted by metabolic plasticity, as tumor cells switch metabolic phenotypes between glycolysis and oxidative phosphorylation (OXPHOS) to compensate for energy. Herein, Metformin (MET) and BAY-876 (BAY) co-loaded CuFe2O4 (CF) nanoplatform (CFMB) is developed to boost energy deprivation by synchronous interventions of glycolysis and OXPHOS for bioenergetic therapy synergetic with chemodynamic/photothermal therapy (CDT/PTT). The MET can simultaneously restrain glycolysis and OXPHOS by inhibiting hexokinase 2 (HK2) activity and damaging mitochondrial function to deprive energy, respectively. Besides, BAY blocks glucose uptake by inhibiting glucose transporter 1 (GLUT1) expression, further potentiating the glycolysis repression and thus achieving much more depletion of tumorigenic energy sources. Interestingly, the upregulated antioxidant glutathione (GSH) in cancer cells triggers CFMB degradation to release Cu+/Fe2+ catalyzing tumor-overexpressed H2O2 to hydroxyl radical (âOH), both impairing OXPHOS and achieving GSH-depletion amplified CDT. Furthermore, upon near-infrared (NIR) light irradiation, CFMB has a photothermal conversion capacity to kill cancer cells for PTT and improve âOH production for enhanced CDT. In vivo experiments have manifested that CFMB remarkably suppressed tumor growth in mice without systemic toxicity. This study provides a new therapeutic modality paradigm to boost bioenergetic-related therapies.
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Glicólise , Metformina , Fosforilação Oxidativa , Terapia Fototérmica , Fosforilação Oxidativa/efeitos dos fármacos , Animais , Camundongos , Terapia Fototérmica/métodos , Glicólise/efeitos dos fármacos , Humanos , Metformina/farmacologia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Metabolismo Energético/efeitos dos fármacos , Neoplasias/terapia , Neoplasias/metabolismoRESUMO
Chemodynamic therapy (CDT), which suppresses tumors via the conversion of endogenous hydrogen peroxide (H2O2) to highly toxic hydroxyl radicals (â¢OH), is deemed as a cutting-edge antitumor strategy. However, the insufficient endogenous H2O2 and up-regulated antioxidant glutathione (GSH) in the tumor microenvironment (TME) greatly impede the therapeutic effect of CDT. Herein, a versatile nanoplatform MgO2@SnFe2O4@PEG (MSnFeP) is elaborately fabricated for boosting CDT synergetic phototherapy. In the TME, the activation of MSnFeP contributes to in situ supply of H2O2, generation of â¢OH and consumption of GSH for boosted CDT. Furthermore, photothermal therapy (PTT) and photodynamic therapy (PDT) are simultaneously stimulated by near-infrared (NIR) light exposure on MSnFeP to increase the toxic free radical yield. This strategy not only amplifies the CDT efficacy hindered by H2O2 deficiency and GSH overexpression, but also further enhances the therapeutic effect with the combination of phototherapy.
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Peróxido de Hidrogênio , Neoplasias , Humanos , Antioxidantes , Óxido de Magnésio/uso terapêutico , Linhagem Celular Tumoral , Fototerapia , Glutationa , Neoplasias/tratamento farmacológico , Microambiente TumoralRESUMO
Chemodynamic therapy (CDT), which employs Fenton/Fenton-like agents to decompose hydrogen peroxide (H2O2) into toxic hydroxyl radical (â¢OH) to induce cancer cell apoptosis and necrosis, holds great promise in tumor therapy due to its high selectivity. Nevertheless, its efficiency is impaired by the insufficient intracellular H2O2 concentration and/or the insensitive response of Fenton/Fenton-like agents to the slightly acid tumor microenvironment (pHâ¼7.0-6.5). Herein, we develop a novel CDT reagent based on CeO2 quantum dot (QD) decorated MgO2 nanosheets engineered with cascade reactions to boost the intracellular H2O2 level and high pH-activated (pH = 6.5) characteristic for an enhanced CDT. Under the tumor microenvironment (pH = 6.5), MgO2 nanosheets that are highly reactive can react with H2O to produce nontoxic Mg2+ and abundant H2O2, boosting the intracellular H2O2 level. The self-generated H2O2 is subsequently converted into â¢OH by CeO2 QD, which is served as a relatively high pH-activated (pH = 6.5) Fenton-like agent. The sufficient intracellular H2O2 supply and sensitive response to the slightly acid tumor sites significantly improve the Fenton reaction, leading to the excellent in vivo CDT results with tumor growth inhibition effect. Our work presents a distinctive paradigm for self-boosting CDT efficacy.
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Peróxido de Hidrogênio , Neoplasias , Humanos , Peróxido de Hidrogênio/farmacologia , Óxido de Magnésio/farmacologia , Microambiente Tumoral , Radical Hidroxila , Neoplasias/patologia , Linhagem Celular TumoralRESUMO
Selective hydrogenation of carbon monoxide (CO) to higher alcohols (C2+OH) is a promising non-petroleum route for producing high-value chemicals, in which precise regulations of both C-O cleavage and C-C coupling are highly essential but remain great challenges. Herein, we report that highly selective CO hydrogenation to C2-4OH is achieved over a potassium-modified edge-rich molybdenum disulfide (MoS2) catalyst, which delivers a high CO conversion of 17% with a superior C2-4OH selectivity of 45.2% in hydrogenated products at 240 °C and 50 bar, outperforming previously reported non-noble metal-based catalysts under similar conditions. By regulating the relative abundance of edge to basal plane, C2-4OH to methanol selectivity ratio can be overturned from 0.4 to 2.2. Mechanistic studies reveal that sulfur vacancies at MoS2 edges boost carbon-chain growth by facilitating not only C-O cleavage but also C-C coupling, while potassium promotes the desorption of alcohols via electrostatic interaction with hydroxyls, thereby enabling preferential formation of C2-4OH.
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The quick-scanning XAFS (QXAFS) method is achieved at the BL14W1 XAFS beamline at the Shanghai Synchrotron Radiation Facility based on the EPICS and LabVIEW systems. This is realised by the unprecedented use of LabVIEW's data logging and supervisory control module for communication with EPICS in synchrotron radiation facilities. A fine QXAFS spectrum with an energy range of 1.2 keV at the Cu K-edge has been collected in 2 s with stable beam position and the data quality is comparable with that of the step-mode XAFS spectrum. Analog-to-digital converter and double-crystal monochromator set-ups have been optimized in order to acquire optimal parameters for the QXAFS experiments. Signal-to-noise ratios of these spectra have been calculated in order to estimate the importance of these parameters.
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The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.
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The novel bifunctional NH2-MIL-125/Co(dmgH)2 composite catalysts with several different Co(dmgH)2 contents that can simultaneously achieve photocatalytic NO removal and hydrogen production were first prepared by a simple and convenient method. The corresponding physical and chemical properties of the composite catalysts were characterized by SEM, XRD, ESR, in situ DRIFTS, etc. The characterization results indicated that the noble-metal-free Co(dmgH)2, which was much cheaper and more available than most noble-metals such as Pt, could be an effective co-catalyst to accelerate the separation of photogenerated electron-hole pairs, further eventually enhancing the photocatalytic efficiency. Under visible-light irradiation for half an hour, the NO removal ratio of NH2-MIL-125/Co(dmgH)2 (3 wt%) increased by 22.7 % compared with the pristine NH2-MIL-125 without Co(dmgH)2 loading. In addition, it was found that Eosin Y dye-sensitized NH2-MIL-125/Co(dmgH)2 (3 wt%) was capable of promoting a hydrogen generation rate of 2195 µmol g-1 h-1 under visible light, which was 12.6 times greater than the original NH2-MIL-125. This strategy was expected as an available way to fabricate noble-metal-free molecular complexes with metal-organic frameworks (MOFs) to enhance the photocatalytic NO removal and hydrogen production performance simultaneously.
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The components and structures of ionic liquid ChCl-ZnCl(2) in different ChCl:ZnCl(2) ratios were investigated using XAFS (X-ray absorption fine structure) technique. The average coordination number and distance of Zn species at different x(ZnCl(2)) (mole fraction of ZnCl(2) when synthesizing) were calculated. It is shown that x(ZnCl(2)) has a regular influence on the coordination number of Zn species, due to the change of anion forms and structures in the ChCl-ZnCl(2) ionic liquid. The possible forms and structures of Zn species in the ionic liquids were analyzed according to the coordination number. XAFS and DSC (differential scanning calorimetry) analysis imply that besides ZnCl(3)(-) and Zn(2)Cl(5)(-) anions, the Cl-Zn-Cl ion pair is a main species in the ionic liquid at higher x(ZnCl(2)). This newly discovered Zn species has substantial influence on the properties of the ionic liquid. From the analysis of the coordination numbers and coordination distance, a new mechanism of interactions between Ch(+) cation and Cl-Zn-Cl ion pairs or Cl(-) is proposed.
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Cloretos/química , Etanolaminas/química , Líquidos Iônicos/química , Compostos de Zinco/química , Varredura Diferencial de Calorimetria , Estrutura Molecular , Análise Espectral/métodos , Temperatura , Raios XRESUMO
SmB6 has been a well-known Kondo insulator for decades, but recently attracts extensive new attention as a candidate topological system. Studying SmB6 under pressure provides an opportunity to acquire the much-needed understanding about the effect of electron correlations on both the metallic surface state and bulk insulating state. Here we do so by studying the evolution of two transport gaps (low temperature gap El and high temperature gap Eh) associated with the Kondo effect by measuring the electrical resistivity under high pressure and low temperature (0.3â¯K) conditions. We associate the gaps with the bulk Kondo hybridization, and from their evolution with pressure we demonstrate an insulator-to-metal transition at â¼4â¯GPa. At the transition pressure, a large change in the Hall number and a divergence tendency of the electron-electron scattering coefficient provide evidence for a destruction of the Kondo entanglement in the ground state. Our results raise the new prospect for studying topological electronic states in quantum critical materials settings.
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Substitutional heterovalent doping represents an effective method to control the optical and electronic properties of nanocrystals (NCs). Highly monodisperse II-VI NCs with deep substitutional dopants are presented. The NCs exhibit stable, dominant, and strong dopant fluorescence, and control over n- and p-type electronic impurities is achieved. Large-scale, bottom-up superlattices of the NCs will speed up their application in electronic devices.