Chemical bond properties and charge transfer bands of O²⁻–Eu³⁺, O²⁻–Mo⁶⁺ and O²⁻–W⁶⁺ in Eu³⁺-doped garnet hosts Ln₃M<sub>5</

Liu, Xiaoguang,Li, Ling,Noh, Hyeon Mi,Moon, Byung Kee,Choi, Byung Chun,Jeong, Jung Hyun The Royal Society of Chemistry 2014 Dalton Transactions Vol.43 No.23

<P>Charge transfer (CT) energy from the ligand to the central ions is an important factor in luminescence properties for rare earth doped inorganic phosphors. The dielectric theory of complex crystals was used to calculate chemical bond properties. Combining the photoluminescence and the dielectric theory of complex crystals, the CT bands of O<SUP>2−</SUP>–Eu<SUP>3+</SUP>, O<SUP>2−</SUP>–Mo<SUP>6+</SUP> and O<SUP>2−</SUP>–W<SUP>6+</SUP> for Eu<SUP>3+</SUP>-doped inorganic phosphors have been investigated experimentally and theoretically. Taking Eu<SUP>3+</SUP>-doped Ln<SUB>3</SUB>M<SUB>5</SUB>O<SUB>12</SUB> (Ln = Y, Lu and M = Al, Ga), Gd<SUB>3</SUB>Ga<SUB>5</SUB>O<SUB>12</SUB>, MMoO<SUB>4</SUB> (M = Ca, Sr, Ba) and MWO<SUB>4</SUB> (M = Ca, Sr, Ba) as typical phosphors, we investigated the effects of the cation size on the CT bands and chemical bond properties including the bond length (<I>d</I>), the covalency (<I>f</I><SUB>c</SUB>), the bond polarizability (<I>α</I><SUB>b</SUB>) and the environmental factor (<I>h</I><SUB>e</SUB>) of O<SUP>2−</SUP>–Eu<SUP>3+</SUP>, O<SUP>2−</SUP>–Mo<SUP>6+</SUP> and O<SUP>2−</SUP>–W<SUP>6+</SUP>, respectively. For systematic isostructural Ln<SUB>3</SUB>M<SUB>5</SUB>O<SUB>12</SUB> (Ln = Y, Lu and M = Al, Ga) phosphors, with the increasing M ion radius, the bond length of Ln–O decreases, but <I>f</I><SUB>c</SUB> and <I>α</I><SUB>b</SUB> increase, which is the main reason that the environmental factor increased. For the isostructural MMoO<SUB>4</SUB>:Eu, with the increasing M ion radius, the Mo–O bond length increases, but <I>f</I><SUB>c</SUB> and <I>α</I><SUB>b</SUB> decrease, and thus <I>h</I><SUB>e</SUB> decreases. However, in the compound system MWO<SUB>4</SUB>:Eu (M = Ca, Ba) with the increasing M ion radius, the O–W bond length increases, but <I>f</I><SUB>c</SUB> and <I>α</I><SUB>b</SUB> increase, and thus <I>h</I><SUB>e</SUB> increases and the O–W CT energy decreases. Their O<SUP>2−</SUP>–Eu<SUP>3+</SUP>, O<SUP>2−</SUP>–Mo<SUP>6+</SUP> and O<SUP>2−</SUP>–W<SUP>6+</SUP> CT bands as well as their full width at half maximum (FWHM) were directly influenced by <I>h</I><SUB>e</SUB>. And with the increasing <I>h</I><SUB>e</SUB>, CT bands of O–Eu or O–Mo or O–W decrease and their FWHM increases. These results indicate a promising approach for changing the material properties, searching for new Eu<SUP>3+</SUP> doped molybdate, tungstate or other oxide phosphors and analyzing the experimental result.</P> <P>Graphic Abstract</P><P>With the increasing environmental factor <I>h</I><SUB>e</SUB>, their O–Mo or O–W or O–Eu CT energy decreases and FWHM increases. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4dt00674g'> </P>

Leakage Flux Adjustment and Flux Field Optimization for Coreless Axial Flux Permanent Magnet Synchronous Machine Based on U-shaped Iron

Wang Xiaoguang,Yin Hao,Liu Cheng,Li Xiaofeng,Zhang Guoguang,Liu Yi,Xu Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

The rotor leakage flux will cause a lot of eddy current losses in the windings of coreless axial flux permanent magnet synchronous machine (CAFPMSM). This article presents a rotor leakage flux adjustment method for the CAFPMSM based on U-shaped iron, which can also achieve the optimization of the rotor flux field. The U-shaped iron can reduce the leakage flux crosses the winding and improve the spatial harmonic distribution of the air gap field at the same time. Firstly, the basic topology and its operating principle are investigated by using an equivalent magnetic circuit model. And then, the characteristics of the flux field distribution in the winding area are analyzed, and the parameters of the U-shaped iron on the leakage flux path regulation are elaborated and optimized by the three-dimensional finite-element method (3D FEM) analysis. Finally, the comprehensive experimental results show that the leakage flux path of the rotor passes through the U-shaped magnetically conductive block rather than through the windings, the total harmonic distortion (THD) of the air gap flux density waveform can be significantly decreased, and the THD of the back EMF and the eddy current losses are lower than before.

Deep sequencing identifies conserved and novel microRNAs from antlers cartilage of Chinese red deer (Cervus elaphus)

Yanxia Chen,Xuedong Liu,Xiaoguang Yang,Yuhui Liu,Xiaomeng Pi,Qingzhen Liu,Dong Zheng 한국유전학회 2015 Genes & Genomics Vol.37 No.5

Deer antlers are the only mammalian appendages subject to an annual cycle of epimorphic regeneration. Within the rapid-growth stage, they display the fastest cartilage development in the animal kingdom. To identify microRNA (miRNA) profiling in red deer (Cervus elaphus) antler cartilage, we applied deep sequencing technology to a small RNA library constructed from pooled cartilage (three antlers from three individuals). We generated 9,520,645 mappable reads with a size distribution of between 15 and 30 nucleotides (miRNAs of 18 nucleotides were the most abundant group: 31 %). Bioinformatics data mining revealed 399 miRNAs in antler cartilage, of which 345 were highly conserved and expressed in 25 other mammals, including the cattle (Bos taurus) and in humans (Homo sapiens). The remaining 54 miRNAs we identified were novel and likely to be antler-cartilage specific, but were expressed at low levels. The identification of these known and newly identified miRNAs in antler cartilage significantly enhances our understanding of the miRNA profiling of regenerating antler cartilage. Further studies are necessary to better understand miRNAs-regulated antlerogenesis.

A nearly precise definition of fairness and a novel method for curve fairing

Xiaoguang Han,Ligang Liu,Guangchang Dong (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

Seismic Rotational Stability Analysis of Gravity Retaining Wall under Heavy Rainfall

Xiaoguang Li,Jie Liu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

A new methodology for the rotational stability analysis of a gravity retaining wall supporting inclined backfill under earthquake and heavy rainfall conditions has been presented.According to the movement mode of retaining wall and the characteristics of backfill sliding and rainwater infiltration, a sliding model of the infinite soil strip and rainwater infiltration model were established respectively. By calculating the internal energy dissipation rate and external loads power of the wall-soil system mechanism, a formula to calculate seismic yield acceleration coefficient under coupling conditions of earthquakes and rainfall was deduced.The results revealed a large effect size of infiltration depth of rainwater and the backfill inclination on the seismic yield acceleration coefficient. When the rainwater reaches 1/5 the height of the retaining wall and the backfill inclination exceeds 15°, the seismic yield acceleration coefficient will decrease rapidly. Moreover, the results obtained in this paper showed good consistency with those obtained by numerical simulation.

Value sharing results of a meromorphic function f(z) and f(qz)

Xiaoguang Qi,Kai Liu,Lianzhong Yang 대한수학회 2011 대한수학회보 Vol.48 No.6

In this paper, we investigate sharing value problems related to a meromorphic function f(z) and f(qz), where q is a non-zero constant. It is shown, for instance, that if f(z) is zero-order and shares two valves CM and one value IM with f(qz), then f(z)=f(qz).

Level Set Based Path Planning Using a Novel Path Optimization Algorithm for Robots

Xiaoguang Zhang,Wei Zhang,Hui Li,Mingqin Liu,류성기 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.9

In order to decrease the path length and control the minimum distance between the path and the obstacles when the level set based path planning algorithm is adopted , a new path optimization algorithm named elastic particle is proposed in this paper. Firstly, the iteration expression of optimization algorithm is deduced by active contour theory. Secondly, to ensure the convergence of algorithm, the relation among each item in the algorithm expression is analyzed and its convergence condition is determined. At last, level set algorithm is improved so that the smoothness of the initial path and the convergence speed of the algorithm are improved. In addition, a method named the nearest boundary distance is put forward to accelerate the operation speed of the algorithm. What’s more, memory pool and binary sort tree are adopted in the code to further reduce the running time of this algorithm. The optimal values of the algorithm parameters are analyzed via the simulation experiment,and its result demonstrates that the new algorithm has greatly optimized the path of algorithm-level set and guaranteed fast running speed and high reliability.

VALUE SHARING RESULTS OF A MEROMORPHIC FUNCTION f(z) AND f(qz)

Qi, Xiaoguang,Liu, Kai,Yang, Lianzhong Korean Mathematical Society 2011 대한수학회보 Vol.48 No.6

In this paper, we investigate sharing value problems related to a meromorphic function f(z) and f(qz), where q is a non-zero constant. It is shown, for instance, that if f(z) is zero-order and shares two valves CM and one value IM with f(qz), then f(z) = f(qz).

Fabrication of the Pesticide-Attapulgite composites regulated by mixed-surfactants

Jiexiang Liu,Ruili Bai,Xiaoguang Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

The SB (DTAB, TTAB, CTAB, OTAB)-AP complex was obtained by modifying attapulgite (AP) with surfactantof SB (DTAB, TTAB, CTAB, OTAB). The structures were characterized by XRD, FT-IR, TGA/DTA and SEM. A new lamellar structure is formed by introducing surfactant. The basal spacing increases with theincrease of alkyl chain length of cationic surfactants. Then, the beta-cypermethrin (BCT) composites ofBCT/SB-AP, BCT/DTAB (TTAB, CTAB, OTAB)-SB-AP were prepared and investigated. The basal spacingsof BCT composites were larger than those of SB-AP and the corresponding DTAB (TTAB, CTAB, OTAB)-AP. The existence of BCT and surfactants molecules into BCT composites was further confirmed. TheBCT/DTAB (TTAB, CTAB, OTAB)-SB-AP have the smaller specific surface areas than DTAB (TTAB, CTAB,OTAB)-AP due to the increase of AP exfoliation in the presence of SB. Fabrication mechanism of BCT compositeswas put forward. Release behaviors of BCT were investigated and analyzed in different buffersolutions. The existence of mixed-surfactants influenced distinctly the release rates. BCT compositeshad the slow release property. The release behaviors were well fitted by pseudo second-order and parabolicdiffusion models. This study provided a new approach to improve the utilization efficiency of pesticideand could be applied as a pesticide delivery system.

Photoluminescence of rare earth ions coactivated Ca₉Y(VO₄)₇ with cold, natural and warm white emission

Li, Ling,Liu, Xiaoguang,Noh, Hyeon Mi,Moon, Byung Kee,Choi, Byung Chun,Jeong, Jung Hyun Elsevier 2015 Materials chemistry and physics Vol.158 No.-

<P><B>Abstract</B></P> <P>It has been still a challenge to obtain a new single-component white-light phosphor with the vanadates as host lattices and with two types of ions as activators. A systematic Ln<SUB>1</SUB> <SUP>3+</SUP>/Ln<SUB>2</SUB> <SUP>3+</SUP> (Ln<SUB>1</SUB> <SUP>3+</SUP>/Ln<SUB>2</SUB> <SUP>3+</SUP> = Dy<SUP>3+</SUP>/Tm<SUP>3+</SUP> or Dy<SUP>3+</SUP>/Sm<SUP>3+</SUP> or Dy<SUP>3+</SUP>/Eu<SUP>3+</SUP> or Tm<SUP>3+</SUP>/Eu<SUP>3+</SUP> or Tm<SUP>3+</SUP>/Sm<SUP>3+</SUP>) coactivated Ca<SUB>9</SUB>Y(VO<SUB>4</SUB>)<SUB>7</SUB> (CYV)samples as well as their singly doped CYV phosphors have been synthesized by the traditional solid state reaction and their photoluminescence properties have been investigated. The photoluminescence properties as a function of the concentration of rare earth ions have been discussed and the tunable luminescent color was found. The warm (CYV: 1%Dy<SUP>3+</SUP>, 1%Sm<SUP>3+</SUP>), natural (CYV: 7% Tm<SUP>3+</SUP>,0.5% Eu<SUP>3+</SUP>; CYV: 1.0% Tm<SUP>3+</SUP>, 0.5% Sm<SUP>3+</SUP>), and cold (CYV: 3% Tm<SUP>3+</SUP>,0.5% Eu<SUP>3+</SUP>; CYV: 0.5% Dy<SUP>3+</SUP>,0.5% Tm<SUP>3+</SUP>; CYV: 0.5% Dy<SUP>3+</SUP>,0.7% Tm<SUP>3+</SUP>; CYV: 0.3%Dy<SUP>3+</SUP>, 0.5% Tm<SUP>3+</SUP>) white lights can be obtained. Generally, the emission intensity or lifetime of one rare earth ions decreases with increasing of the concentration of another rare earth ions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photoluminescence properties of rare earth ions coactivated Ca<SUB>9</SUB>Y(VO<SUB>4</SUB>)<SUB>7</SUB> were investigated. </LI> <LI> The effects of rare earth ions concentration on photoluminescence have been discussed. </LI> <LI> The tunable luminescent color was found. </LI> <LI> Cold, natural and warm white emissions were obtained. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>