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Yuze Li,Huijun Chen 대한자기공명의과학회 2020 Investigative Magnetic Resonance Imaging Vol.24 No.4
Purpose: To generate the under-sampling pattern using a self-supervised learning framework based on a graph convolutional network. Materials and Methods: We first decoded the k-space data into the graph and put it into the network. After the processing of graph convolution layers and graph pooling layers, the network generated the under-sampling pattern for MR reconstruction. We trained the network on the simulated brain dataset enabled by the selfsupervised learning strategy. We did simulation along with the in vivo brain and liver experiments under different noise levels and accelerating factors to compare the performance between the proposed method and traditional methods using the PSNR and SSIM index. Results: The simulation experiments showed that the proposed method can achieve the best performance with low accelerating factors (2 and 3) at all noise levels and in high accelerating factors (4 and 5) at high noise levels (50 and 70 dB). In in vivo experiments, the proposed method attained the highest PSNR and SSIM in the brain dataset as well as in the liver dataset after fine tuning on a small liver dataset. Conclusion: The self-supervised learning framework based on a graph convolutional network was able to design the under-sampling mask for MR reconstruction. The superior performance in the simulation and in vivo experiments demonstrated the feasibility and flexibility of the proposed method and its potential in clinical use.
Lu, Yuting,Chen, Luyang,Li, Yuze,Xie, Hongde,Cheng, Han,Jin Seo, Hyo Elsevier 2016 Materials letters Vol.164 No.-
<P><B>Abstract</B></P> <P>The work reports the large-scale synthesis and photocatalytic activity of Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> nanoplates. The structural refinement was conducted in the layered δ-Bi<SUB>2</SUB>O<SUB>3</SUB> based superstructuLre. The detailed surface properties were characterized. Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> shows efficient absorption in visible region with a band-gap of 2.384eV from the hybridization of Bi-6s and O-2p orbitals. Particularly, Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> shows an efficient photodegradation for methylene blue (MB). The photocatalysis benefits from the layered B–O structure characteristic and the codoped defects of V<SUP>4+</SUP>/V<SUP>5+</SUP> ions in the lattices. Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> nanoplates could be a potential photocatalyst.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> nanoplates were prepared by the Pechini method. </LI> <LI> It has a narrow band-gap of 2.384eV from hybridization of Bi-6s and O-2p. </LI> <LI> Bi<SUB>23</SUB>V<SUB>4</SUB>O<SUB>44.5</SUB> has photocatalysis report visible-light-irradiation. </LI> <LI> Photocatalysis is due to layered δ-Bi<SUB>2</SUB>O<SUB>3</SUB>-like structure and codoped V<SUP>4+</SUP>/V<SUP>5+</SUP> ions. </LI> </UL> </P>
Yang, Li,Wan, Yingpeng,Li, Yuze,Pu, Yinfu,Huang, Yanlin,Chen, Cuili,Seo, Hyo Jin Springer-Verlag 2016 JOURNAL OF NANOPARTICLE RESEARCH Vol.18 No.4
<P>Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was conducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photoluminescence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca2B2O5:Eu3+ nanofibers show the red luminescence with CIE coordinates of (x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca2B2O5:Tb3+ nanofibers is green color (x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy3+-doped Ca2B2O5 nanofibers present a singlephase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu3+-, Tb3+-, Dy3+-doped Ca2B2O5 nanofibers, respectively. It is suggested that Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers could be an efficient phosphor for lighting and display.</P>