A series of Ce(1-x)M(x)O(2-δ) (M = Gd, Zr, La, Sm, Y, Lu, and Pr) samples were characterized by Raman spectroscopy to investigate the evolution of defect sites (oxygen vacancies and MO(8)-type complex) and their distributions in the samples. It was found that the evolution of oxygen vacancies was due to the different ionic valence state of dopant from that of Ce(4+), while the evolution of the MO(8)-type complex was due to the different ionic radius of dopant from that of Ce(4+). The distributions of defect sites were investigated using 325 and 514 nm excitation laser lines, indicating that the defect sites were surface enriched. Moreover, the increasing ordering level of the sample led to a decline in the concentration of the MO(8)-type complex in the sample but the constant concentration of oxygen vacancies, implying that the metastable MO(8)-type complex species were more disordered compared to the oxygen vacancies.
Monodisperse colloidal quantum dots with size dispersions o10% are of great importance in realizing functionality manipulation, as well as building advanced devices, and have been normally synthesized via 'bottom-up' colloidal chemistry. Here we report a facile and environmentally friendly 'top-down' strategy towards highly crystalline monodisperse colloidal PbS quantum dots with controllable sizes and narrow dispersions 5.5%oso9.1%, based on laser irradiation of a suspension of polydisperse PbS nanocrystals with larger sizes.The colloidal quantum dots demonstrate size-tunable near-infrared photoluminescence, and self-assemble into well-ordered two-dimensional or three-dimensional superlattices due to the small degree of polydispersity and surface capping of 1-dodecanethiol, not only serving as a surfactant but also a sulphur source. The acquisition of monodisperse colloidal PbS quantum dots is ascribed to both the quantum-confinement effect of quantum dots and the size-selective-vaporization effect of the millisecond pulse laser with monochromaticity and low intensity.
BackgroundIschemia/reperfusion (I/R) injury is associated with systemic inflammatory response. Macrophage migration inhibitory factor (MIF) has been implicated in many inflammatory processes. Tanshinone IIA (TSA) is one of the active ingredients in danshen, which derived from the dried root or rhizome of Salviae miltiorrhizae Bge. Recent studies have demonstrated that TSA has protective effects against focal cerebral I/R injury. However, little is known about the underlying mechanisms. Here we put forward the hypothesis that TSA acts through inhibition of MIF expression during focal cerebral I/R injury in rats.Methodology/Principal FindingsRats were subjected to middle cerebral artery occlusion (MCAO) for 2 hours. This was followed by reperfusion. We measured neurological deficits, brain water content, and infarct volume, and found that neurological dysfunction, brain edema, and brain infarction were significantly attenuated by TSA 6 hours after reperfusion. We also measured myeloperoxidase (MPO) activity at 6 and 24 hours, and found that neutrophil infiltration was significantly higher in the vehicle+I/R group than in the TSA+I/R group. ELISA demonstrated that TSA could inhibit MIF expression and the release of TNF-α and IL-6 induced by I/R injury. Western blot analysis and immunofluorescence staining showed that MIF expression was significantly lower in the TSA+I/R group than in the vehicle+I/R group. MIF was found almost all located in neurons and hardly any located in astrocytes in the cerebral cortex. Western blot analysis and EMSA demonstrated that NF-κB expression and activity were significantly increased in the vehicle+I/R group. However, these changes were attenuated by TSA.Conclusion/SignificanceOur results suggest that TSA helps alleviate the proinflammatory responses associated with I/R-induced injury and that this neuroprotective effect may occur through down-regulation of MIF expression in neurons.
With the development of novel optoelectronic materials and nanofabrication technologies, integrated photonics is a rapidly developing field that will promote the development and application of next‐generation photonic devices. In recent years, emerging two‐dimensional materials (2DMs) including graphene, transition metal dichalcogenides (TMDCs), black phosphorus (BP), and ternary compounds show many complementarities and unique characteristics over those of traditional optoelectronic materials including broadband absorption, ultrafast carrier mobility, strong nonlinear effects, and compatibility for monolithic integration. Herein, the recent progress on waveguide‐integrated active devices for a full photonic circuit based on 2DMs is reviewed. Both the development of nanofabrication techniques and the working mechanism of active photonic components based on 2DMs containing integrated light sources, waveguide‐integrated modulators, photodetectors, as well as some advanced 2DMs‐based optoelectronic devices are illustrated in detail. In the end, the existing challenges and perspectives on novel 2DMs‐integrated photonics are summarized and discussed.
Danshen, derived from the dried root or rhizome of Salviae miltiorrhizae BGE., has Tanshinone IIA (TSA) as one of its active ingredients. Recent reports have shown that TSA can inhibit the apoptosis induced by serum withdrawal or ethanol in cultured PC12 cells. However, whether TSA has any neuroprotective effect remains unknown. In this study, we investigated the effects of TSA on cerebral apoptosis induced by middle cerebral artery occlusion (MCAO) in which cerebral ischemia had been induced 2 h earlier. Twenty-four hours after reperfusion, the rats were assessed for infarct volume etc. Intraperitoneal administration of 25 and 40 mg/kg TSA 10 min after MCAO significantly diminished infarct volume and brain water content and improved neurological deficits in a dose-dependent manner. The 25 mg/kg dosage was more effective. Treatment with 25 mg/kg TSA significantly improved symptoms and reduce infarct volume at different points in time, of which 10 min after MCAO was the most significant. Nissl-staining and HE-staining of the 25 mg/kg TSA group were more appreciable in terms of improvement relative to the vehicle group in the infarct core. TSA of dosage 25 mg/kg significantly decreased the expression of cleaved caspase-3 protein and increased the expression of B-cell lymphoma 2 (bcl-2) protein in the ischemic cortex. Fewer terminal deoxyribonucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling (TUNEL)-positive cells were found in the penumbra of the treated group, but they were significantly more common in the vehicle group. We here conclude that the neuroprotective effects of TSA against focal cerebral ischemic/reperfusion injury are likely to be related to the attenuation of apoptosis.
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