Improvement of the Thermoelectric Properties of p-Type Mg3Sb2 by Mg-Site Double Substitution.

A P-type Mg3Sb2-based Zintl phase compound has been considered a promising candidate for thermoelectric applications. Alloying, which introduces a high concentration of point defects, is particularly effective in scattering phonons and reducing lattice thermal conductivity. Herein, alloying in p-type Mg2.995Na0.005Sb2 via the introduction of elements like Yb, Eu, Ca, and Ba was realized, and the room-temperature lattice thermal conductivity has been effectively reduced to ∼1.1 W m-1 K-1. To further intensify the phonon scattering, two groups of elements (Eu and Cd, and Yb and Cd) were chosen for heavy alloying at the Mg site, and the lattice thermal conductivity of Mg1.49Eu0.5Cd1Na0.01Sb2 was further reduced to ∼0.45 W m-1 K-1. Eventually, a peak zT as high as ∼1.0 was achieved at 773 K, and the compound outperforms the previously reported p-type Mg3Sb2 compounds.

Dynamic PET images denoising using spectral graph wavelet transform.

Positron emission tomography (PET) is a non-invasive molecular imaging method for quantitative observation of physiological and biochemical changes in living organisms. The quality of the reconstructed PET image is limited by many different physical degradation factors. Various denoising methods including Gaussian filtering (GF) and non-local mean (NLM) filtering have been proposed to improve the image quality. However, image denoising usually blurs edges, of which high frequency components are filtered as noises. On the other hand, it is well-known that edges in a PET image are important to detection and recognition of a lesion. Denoising while preserving the edges of PET images remains an important yet challenging problem in PET image processing. In this paper, we propose a novel denoising method with good edge-preserving performance based on spectral graph wavelet transform (SGWT) for dynamic PET images denoising. We firstly generate a composite image from the entire time series, then perform SGWT on the PET images, and finally reconstruct the low graph frequency content to get the denoised dynamic PET images. Experimental results on simulation and in vivo data show that the proposed approach significantly outperforms the GF, NLM and graph filtering methods. Compared with deep learning-based method, the proposed method has the similar denoising performance, but it does not need lots of training data and has low computational complexity.

Influence of glaucoma surgery on the ocular surface using oculus keratograph.

PURPOSE: To investigate the influence of trabeculectomy and phacotrabeculectomy on the ocular surface. DESIGN: Retrospective, case-control study. METHODS: Eighty-one samples without dry eyes were recruited and divided into three groups, including phacoemulsification group (N = 30) as control group, trabeculectomy group (N = 27) and phacotrabeculectomy group (N = 24) as study groups. Ocular surface parameters, including noninvasive keratograph first (NifBUT) and average (NiaBUT) tear film breakup time, tear meniscus height (TMH) and corneal fluorescein stain (CFS), were estimated preoperatively, at 3 days, 1 month and 3 months postoperatively using oculus keratograph. RESULTS: No significant difference was observed in ocular surface parameters at baseline among three groups (p > 0.05). The magnitude of NifBUT and NiaBUT was reduced at 3 days and 1 month postoperatively in phacotrabeculectomy group, but greater than that in the other two groups (All p < 0.001). In all the groups, both the NifBUT and NiaBUT tended to recover at 1 and 3 months postoperatively, whereas both of them did not recover to baseline at 3 months postoperatively in trabeculectomy (NifBUT, p = 0.001; NiaBUT, p < 0.001) and phacotrabeculectomy group (NifBUT, p < 0.001; NiaBUT, p = 0.020). TMH was raised at 3 days postoperatively and restored to the baseline level at 1 and 3 months postoperatively for three groups (p > 0.05). CFS was elevated at 3 days postoperatively and different in recovery at 1 and 3 months postoperatively for three groups. CONCLUSIONS: The influence of phacotrabeculectomy on ocular surface is worse than that of trabeculectomy for the short run and is not distinct different for a long time.