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Wang, Xiangfu,Bu, Yanyan,Yan, Xiaohong,Cai, Peiqing,Wang, Jing,Qin, Lin,Vu, Thiquynh,Seo, Hyo Jin OPTICAL SOCIETY OF AMERICA 2016 Optics letters Vol.41 No.22
<P>Understanding site-selective fluorescence is one of valuable importance for spectrum modulation. In this Letter, we observed the existence of two non-equivalent Gd-activated crystallographic sites in an Er3+-doped hexagonal Na1.5Gd1.5F6 phosphor. It is proved that two green emissions from the S-4(3/2) level separately originate from the Gd1 (540 nm) and Na2/Gd2 (550-555 nm) crystallographic sites, and the 657 nm red emission from the F-4(9/2) level only originates from Na2/Gd2 site through using the time-resolved luminescence spectra. The 142.2% absolute enhancement of the red emission is realized through the synergistic effect of ultraviolet downconversion and infrared upconversion induced by the 370 nm and 1.54 mu m dual-mode excitation. (C) 2016 Optical Society of America</P>
Fabrication, photoluminescence and applications of quantum dots embedded glass ceramics
Xue, Junpeng,Wang, Xiangfu,Jeong, Jung Hyun,Yan, Xiaohong Elsevier 2020 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.383 No.-
<P><B>Abstract</B></P> <P>Quantum dots (QDs) embedded glass ceramics have been widely studied in laser crystals, LEDs, optical fiber amplifiers, optoelectronic devices, photocatalysts and sensors owing to the size dependent multicolor fluorescence emissions, crystal field controllability, high transparency and stability, and high temperature sensitivity. The rapid advancements of QDs embedded glass ceramics are reviewed in detail. The synthetic methods, crystallization theory, spectral modulation, nonlinear optical property, photoluminescence mechanism, and applications of QDs embedded glass ceramics are exhibited. The most important results obtained in each case are summarized, and the key challenges in market viability are also discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The preparation methods of quantum dots embedded glass ceramics are summarized. </LI> <LI> Crystallization behavior of quantum dots embedded glass ceramics is summarized. </LI> <LI> The luminescence mechanism of QDs embedded glass ceramics is summarized. </LI> <LI> Applications of quantum dots embedded glass ceramics are summarized. </LI> <LI> The future development of quantum dots embedded glass ceramics is predicted. </LI> </UL> </P>
Xue, Junpeng,Wang, Xiangfu,Jeong, Jung Hyun,Yan, Xiaohong The Royal Society of Chemistry 2018 Physical chemistry chemical physics Vol.20 No.17
<P>Bismuth with [Xe]4f<SUP>14</SUP>5d<SUP>10</SUP>6s<SUP>2</SUP>6p<SUP>3</SUP> electronic configuration is considered as ‘a wonder metal’ due to its diverse oxidation states and multi-type electronic structures. This review article summarizes the spectral properties of phosphors doped with Bi<SUP>3+</SUP> or co-doped with Bi<SUP>3+</SUP>-Re<SUP>n+</SUP> (<I>n</I> = 2, 3, 4), and highlights the critical role of Bi<SUP>3+</SUP> in spectral modification. The energy transfer processes are discussed in detail, including (1) Bi<SUP>3+</SUP> and metal-to-metal charge, (2) Bi<SUP>3+</SUP> and tetravalent cation, (3) Bi<SUP>3+</SUP> and trivalent cation, (4) Bi<SUP>3+</SUP> and divalent cation, and (5) Bi<SUP>3+</SUP> and two kinds of rare earth ions. The most important results obtained in each case are summarized, and the emerging challenges and future development of Bi<SUP>3+</SUP>-doped phosphors are discussed. We introduce a method for spectral modification based on the energy transfer between Bi<SUP>3+</SUP> and other cations, with the perspective of development and application in the fields of phosphors, telecommunication, optical temperature sensing, biomedicine, and lasers.</P>
Low velocity impact resistance of ceramic/polyurea composite plates: experimental study
Yihua Xiao,Ziqiang Tang,Xiangfu Hong 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.12
Laminated and segmented ceramic/polyurea composite plates were fabricated by coating bulk ceramic plate and bonding ceramic tablets with polyurea, respectively. Also, nacre-like ceramic/polyurea composite plates, which mimic the “brick-mortar” structure of nacre, were fabricated by layering segmented ceramic/polyurea composite plates in a staggered way and bonding them with polyurea. Drop-weight impact tests were performed for the composite plates and corresponding bulk ceramic plates of similar size. The failure mode and low velocity impact resistance of the composite plates and the bulk ceramic plates were compared. The effects of polyurea on low velocity impact resistance of ceramic were analyzed. It is found that the laminated composite plate has much higher failure energy than the bulk ceramic plate due to the buffering effect of polyurea coating. The segmented composite plate has better multiple-impact resistance than the bulk ceramic plate, due to the crack arrest effect of polyurea filler between ceramic tablets. The nacre-like composite plate has better multipleimpact resistance compared with the bulk ceramic plate of similar thickness, since it can stop cracks propagating in plane and along thickness.
Fan Linfeng,Zeng Xiangfu,Xu Guofeng 한국미생물학회 2023 The journal of microbiology Vol.61 No.1
The correlation of imbalanced gut microbiota with the onset and progression of colorectal cancer (CRC) has become clear. This work investigates the effect of metformin on gut microbiota and genesis of CRC in mice. Human fecal samples were collected from healthy control (HC) donors and CRC patients. Compared to HC donors, CRC patients had reduced abundance of gut microbiota; however, they had increased abundance of detrimental Bacteroidetes. Mice were injected with azomethane (AOM) to induce colorectal tumorigenesis models. Treatment of CRC patients-sourced fecal microbiota promoted tumorigenesis, and it increased the expression of Ki67, β-catenin, COX-2, and Cyclin D1 in mouse colon tissues. Further treatment of metformin blocked the colorectal tumorigenesis in mice. Fecal microbiota from the metformin-treated mice was collected, which showed decreased Bacteroidetes abundance and suppressed AOM-induced colorectal tumorigenesis in mice as well. Moreover, the metformin- modified microbiota promoted the M1 macrophage-related markers IL-6 and iNOS but suppressed the M2 macrophage-related markers IL-4R and Arg1 in mouse colon tissues. In conclusion, this study suggests that metformin-mediated gut microbiota alteration suppresses macrophage M2 polarization to block colorectal tumorigenesis.
NEW RESULTS TO BDD TRUNCATION METHOD FOR EFFICIENT TOP EVENT PROBABILITY CALCULATION
Mo, Yuchang,Zhong, Farong,Zhao, Xiangfu,Yang, Quansheng,Cui, Gang Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.7
A Binary Decision Diagram (BDD) is a graph-based data structure that calculates an exact top event probability (TEP). It has been a very difficult task to develop an efficient BDD algorithm that can solve a large problem since its memory consumption is very high. Recently, in order to solve a large reliability problem within limited computational resources, Jung presented an efficient method to maintain a small BDD size by a BDD truncation during a BDD calculation. In this paper, it is first identified that Jung's BDD truncation algorithm can be improved for a more practical use. Then, a more efficient truncation algorithm is proposed in this paper, which can generate truncated BDD with smaller size and approximate TEP with smaller truncation error. Empirical results showed this new algorithm uses slightly less running time and slightly more storage usage than Jung's algorithm. It was also found, that designing a truncation algorithm with ideal features for every possible fault tree is very difficult, if not impossible. The so-called ideal features of this paper would be that with the decrease of truncation limits, the size of truncated BDD converges to the size of exact BDD, but should never be larger than exact BDD.
Wang, Jing,Bu, Yanyan,Wang, Xiangfu,Seo, Hyo Jin Elsevier 2018 Optical materials Vol.84 No.-
<P><B>Abstract</B></P> <P>Optical thermometry based on the adjacent thermally coupled levels of rare earth ions has been widely studied in the high temperature range, and shows unobvious effect at low temperature range. In this work, we propose a new method to achieve optical thermometry in 10˜300 K range through manipulating the energy transfer from WO<SUB>6</SUB> <SUP>6−</SUP> to Ho<SUP>3+</SUP>. A comprehensive five-level rate-equation model is developed to establish the relation between lifetime ratios and temperature. It is found that the lifetime ratios of 540 nm (Ho<SUP>3+</SUP>) and 471 nm (WO<SUB>6</SUB> <SUP>6−</SUP>) emissions are dependent on the phonon energy of Y<SUB>2</SUB>WO<SUB>6</SUB> host and temperature. The values of sensor sensitivity reach the maximum 2.1% K<SUP>−1</SUP> at 211 K in 30%Ho<SUP>3+</SUP> doped Y<SUB>2</SUB>WO<SUB>6</SUB>, which is higher than the maximum of the reported phosphors at low temperature. It overcomes the shortcoming of unobvious thermal population of thermally coupled levels in low temperature range through traditional Boltzmann distributing method.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Energy transfer process between host and Ho<SUP>3+</SUP> was analyzed. </LI> <LI> Temperature dependent emission spectra of Ho<SUP>3+</SUP> doped Y<SUB>2</SUB>WO<SUB>6</SUB> were studied. </LI> <LI> A new method to achieve optical thermometry through manipulating the energy transfer from WO<SUB>6</SUB> <SUP>6−</SUP> to Ho<SUP>3+</SUP> is proposed. </LI> </UL> </P>