RESUMO
The unique catalytic activities of high-entropy alloys (HEAs) emerge from the complex interaction among different elements in a single-phase solid solution. As a "green" nanofabrication technique, inert gas condensation (IGC) combined with laser source opens up a highly efficient avenue to develop HEA nanoparticles (NPs) for catalysis and energy storage. In this work, the novel N-doped non-noble HEA NPs are designed and successfully prepared by IGC. The N-doping effects of HEA NPs on oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are systematically investigated. The results show that N-doping is conducive to improving the OER, but unfavorable for HER activity. The FeCoNiCrN NPs achieve an overpotential of 269.7 mV for OER at a current density of 10 mA cm-2 in 1.0 M KOH solution, which is among the best reported values for non-noble HEA catalysts. The effects of the differences in electronegativity, ionization energy and electron affinity energy among mixed elements in N-doped HEAs are discussed as inducing electron transfer efficiency. Combined with X-ray photoelectron spectroscopy and the extended X-ray absorption fine structure analysis, an element-design strategy in N-doped HEAs electrocatalysts is proposed to improve the intrinsic activity and ameliorate water splitting performance.
RESUMO
Topologically disordered metallic glass nanoparticles (MGNPs) with highly active and tailorable surface chemistries have immense potential for functional uses. The synthesis of free-standing MGNPs is crucial and intensively pursued because their activity strongly depends on their exposed surfaces. Herein, a novel laser-evaporated inert-gas condensation method is designed and successfully developed for synthesizing free-standing MGNPs without substrates or capping agents, which is implemented via pulse laser-induced atomic vapor deposition under an inert helium atmosphere. In this way, the metallic atoms vaporized from the targets collide with helium atoms and then condense into short-range-order (SRO) clusters, which mutually assemble to form the MGNPs. Using this method, free-standing Pd40 Ni40 P20 MGNPs with a spherical morphology are synthesized, which demonstrates satisfactory electrocatalytic activity and durability in oxygen reduction reactions. Moreover, local structure investigations using synchrotron pair distribution function techniques reveal the transformation of SRO cluster connection motifs of the MGNPs from face-sharing to edge-sharing modes during cyclic voltammetry cycles, which enhances the electrochemical stability by blocking crystallization. This approach provides a general strategy for preparing free-standing MGNPs with high surface activities, which may have widespread functional applications.
RESUMO
Diabetic retinopathy (DR), the most common ocular complication resulting from diabetes in working-age adults, causes vision impairment and even blindness because of microvascular damage to the retina. Melatonin is an endogenous neurohormone possessing various biological properties, including the regulation of oxidative stress, inflammation, autophagy, and angiogenesis functions. To evaluate the effects of melatonin on DR, we first investigated the role of melatonin in retinal angiogenesis and inner blood-retina barrier (iBRB) under high glucose conditions in vitro and in vivo. Melatonin administration ameliorated high glucose-induced iBRB disruption, cell proliferation, cell migration, invasion and tube formation, and decreased the expression levels of VEGF, MMP-2, and MMP-9. Furthermore, melatonin treatment increased the level of autophagy but decreased the expression levels of inflammation-related factors under high glucose conditions. To further explore the underlying mechanism, we evaluated human retinal microvascular endothelial cells (HRMECs) via tandem mass tags (TMT)-labeled quantitative proteomics under high-glucose conditions with or without melatonin. Bioinformatics analysis results revealed that the main enrichment pathway of differentially expressed proteins (DEPs) was the Wnt pathway. We found that melatonin inhibited the activation of Wnt/ß-catenin pathway following DR. These abovementioned protective effects of melatonin under hyperglycemia were blocked by lithium chloride (LiCl; activator of the Wnt/ß-catenin signaling pathway). In summary, melatonin exerts protective effects on experimental DR via inhibiting Wnt/ß-catenin pathway by, at least partially, alleviating autophagic dysfunction and inflammatory activation.
Assuntos
Antioxidantes/uso terapêutico , Barreira Hematorretiniana/efeitos dos fármacos , Retinopatia Diabética/prevenção & controle , Melatonina/uso terapêutico , Via de Sinalização Wnt/efeitos dos fármacos , Animais , Western Blotting , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Retinopatia Diabética/metabolismo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Proteínas do Olho/metabolismo , Masculino , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Proteômica , Ratos , Ratos Sprague-Dawley , Neovascularização Retiniana/tratamento farmacológico , Neovascularização Retiniana/metabolismo , Vasos Retinianos , Espectrometria de Massas em Tandem , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Metallic glasses (MGs) are promising candidates for catalysts with high efficiency for dyeing wastewater remediation, due to their metastable nature, disordered structure, and large residual stresses. However, dyeing wastewater usually contains a high concentration of inorganic ions which may have adverse effects on the degradation process, while the impacts of these ions on MGs' degradation capability have often been overlooked and still remain unknown. Thus, the roles of inorganic ions (Cl-, NO3-, SO42-, and H2PO4-) on the degradation of azo dye by Fe-based MG with nominal composition of Fe81Si4B14Cu1 were systematically investigated. The results showed that the inorganic ions have significant influence on MG's surface morphology, degradation capability, mineralization and durability. All these aspects need to be considered prior to application of MGs for azo dyes degradation in real natural contaminated water or saline wastewater.
Assuntos
Corantes , Águas Residuárias , Compostos Azo , Vidro , ÍonsRESUMO
BACKGROUND: The purpose of this study is to report on reconstruction of complex soft-tissue defects around the metacarpophalangeal joint of the thumb using a bilobed second dorsal metacarpal artery-based island flap taken from the dorsum of the proximal phalanges of the index and long fingers. METHODS: From March of 2007 to October of 2009, the bilobed second dorsal metacarpal artery-based island flap was transferred in 13 patients. There were two defects on the metacarpophalangeal joint of the thumb. The mean size of the dorsal defects was 2.4 × 3.2 cm; the mean size of the volar defects was 2.6 × 4.0 cm. The mean size of the flaps taken from the index and long fingers was 2.6 × 3.4 cm and 2.8 × 3.2 cm, respectively. The mean pedicle length was 4.9 cm. RESULTS: All flaps survived completely. At a mean follow-up of 14 months, the mean active motion arc of the thumb metacarpophalangeal joints was 42 degrees. The motion of the donor fingers was similar to that on the opposite side. The mean values of static two-point discrimination of the donor sites of the index and long fingers were 6 and 7 mm, respectively. CONCLUSION: Transferring the bilobed second dorsal metacarpal artery-based island flap is a useful and reliable technique for reconstructing complex defects around the metacarpophalangeal joint of the thumb. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic IV.