4,218 publications from this institution
Core-shelled multimetallic nanoparticles have unique catalytic properties compared to their single-element counterparts. Due to the different lattice parameters of the core and shell, the strain field is built up at the interface between the two phases. As for thin films, a formation of misfit and threading dislocations is an approach to release interface strain. However, for two-phase nanoparticles especially when their sizes are at nanometer scale, their dislocation formation in the volume remains to be investigated owing to the large surface-to-volume ratio. Here, we confirmed the existence of dislocations in the Au-FePt core-shelled nanoparticles of sizes less than 10 nm. It is suggested that the different atom sizes of the core and the shell materials are likely to be a key factor to generate and lock dislocations inside the nanoparticles.
Structural transformation of gold nanorods are investigated by high-resolution transmission electron microscopy after they have been exposed to low-energy femtosecond and nanosecond laser pulses in colloidal solution. The pulse energies were below the gold nanorod melting threshold, but allowed early stage shape transformation processes. It is found that while the as-prepared nanorods are defect-free, laser-irradiation induces point and line defects. The defects are dominated by (multiple) twins and stacking faults (planar defects), which are the precursor that drives the nanorods to convert their {110} facets into the more stable {100} and {111} facets and hence minimize their surface energy. These observations suggest that short-laser pulsed photothermal melting begins with the creation of defects inside the nanorods followed by surface reconstruction and diffusion, in contrast with the thermal melting of the rods or the bulk material, where the melting starts at the surface.
We tested the hypothesis that the regular inhalation of a beta 2-adrenergic receptor (beta 2AR) agonist increases airway responsiveness in guinea pigs. A potent beta 2AR agonist, fenoterol hydrobromide, in sublaryngeal doses equivalent to maximal doses used in the treatment of asthma on a weight basis (5.28 micrograms/kg), was administered by nebulizer three times a day for 6 weeks to normal adolescent guinea pigs (FEN, n = 10) and to ovalbuminsensitized guinea pigs challenged twice weekly with ovalbumin (OA + FEN, n = 20), although not in the 12 h prior to or 4 h after antigen challenge. Controls included saline-treated normal animals (CON, n = 10) and ovalbumin-sensitized animals treated with repeated antigen challenge and saline (OA, n = 20). At 72 h after the last administration of saline, fenoterol, and ovalbumin, the dose-response relationship between pulmonary resistance (RL) and nebulized acetylcholine (ACh) was measured. RLmax increased 2-fold and the ACh concentration causing a 10-fold increase in RL (PC10) decreased 4-fold in the FEN, OA, and OA + FEN groups as compared to the CON group. In the FEN, OA, and OA + FEN groups, in vitro tracheal smooth-muscle contractile responses to maximal concentrations of acetylcholine increased 2-fold, and this increase was not due to increased smooth-muscle mass. There was no evidence for beta 2AR desensitization as judged by in vitro tracheal smooth-muscle relaxant responses to fenoterol. These results suggest that chronic beta 2AR stimulation increases airway smooth-muscle contractility and in vivo airways responsiveness to a degree similar to that induced by chronic antigen exposure. A similar effect in human asthmatics may explain the adverse effects observed during prolonged treatment with these drugs.
A novel approved algorithm based on template matching is proposed, which could be applied to the real-time tracking system. It composes of correlation matching algorithm, TD filter and ESO filter. This algorithm is used to predict the movement and to track the target. The position of target in the first image is supposed to be known. The problem is then to estimate the position of this template in subsequent images. By TD filter and ESO filter, it is possible to obtain the estimate position of the target in the current image. Then the correlation template matching algorithm is used to search target in the estimation position's neighbor in order to get target's accurate position. The simulation results of the algorithm are presented. The comparative analysis has revealed better performance characteristics of the proposed algorithm in comparison with the traditional template matching algorithm. Experimental results demonstrate the effectiveness of this method.
