The precipitation of three Ca-P phase whiskers from an acid solution through hydrolysis of urea

Yunqing Kang,Yunshan Liu,Zhongbing Huang,Yadong Yao,Xiaoming Liao,Li Liao,Guangfu Yin 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.2

Hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP) and dicalcium phosphate (DCP) whiskers with high aspect ratio and good crystallinity were successfully prepared by hydrolysis of urea in acid solutions at 90oC for 96 h. The precipitated whiskers were characterized by XRD, SEM and TEM. The lengths and aspect ratios of whiskers could be controlled by the precipitation agent, urea, with a proper incubation time. Results revealed good morphology and crystallinity of the precipitated whiskers without any impurities. TEM indicated single crystal diffraction patterns of HA and β-TCP were clearly identified. The high aspect ratio of whiskers could be potentially used as the scaffold in tissue engineering or filler in composite biomaterials to enhance mechanical properties. Hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP) and dicalcium phosphate (DCP) whiskers with high aspect ratio and good crystallinity were successfully prepared by hydrolysis of urea in acid solutions at 90oC for 96 h. The precipitated whiskers were characterized by XRD, SEM and TEM. The lengths and aspect ratios of whiskers could be controlled by the precipitation agent, urea, with a proper incubation time. Results revealed good morphology and crystallinity of the precipitated whiskers without any impurities. TEM indicated single crystal diffraction patterns of HA and β-TCP were clearly identified. The high aspect ratio of whiskers could be potentially used as the scaffold in tissue engineering or filler in composite biomaterials to enhance mechanical properties.

蒙古族的敖包

趙允卿(Zhao Yunqing) 가천대학교 아시아문화연구소 2006 아시아문화연구 Vol.10 No.-

Aobao is a traditional figure in Mongolian folk religion. The historical remains of Aobao are disappearing at an increasing rate. Modern progress has caused people reject folk religion. This has caused less people to make sacrifices or worship. However, throughout the ethnic Mongolian minority of China, Aobao has always been worshiped and adored. In comparison to other folk religions. Aobao's heritage has been preserved. Therefore, Aobao is an important component of ethnic Mongolian Chinese folk tradition. Usually, Aobao is represented by conical stone heaps built beside high mountains, hills, or lakes. Willow tree branches or 'Kaludi(bird-like images) are commonly placed on top of these stone heaps. Aobao is widely used as a symbol of Mongolian nationality's faiths. Other than Mongolian China Aobao can be found in the Ewenke, Elunchun, Dawoer or Xibo areas. Aobao idols are places where people offer sacrifices to Aobao for peace in the community or a bountiful harvest. It is also used as a place for individuals to pray for prosperity in their family. This may include prayers for good heath, healing, or more children. People pray to Aobao regardless of whether good things or bad things have happened. Comfort is found in Aobao during hardship. During happy times people pray prayers of thanks giving and ask for protection in the future. In modern times Aobao is not thought to be an absolutely powerful god, which is the traditional view. Sacrifices are not as central to Aobao worship as it has been in the past. However, traditional Mongolian villages in China still practice traditional faith Aobao. Many see Aobao as a patron saint that is a guide for them. This view has positively affected the community and individuals alike. Aobao is an ambassador of folk religions culture. At the same time Aobao is a historical figure that bear witness to folk religious tradition. Therefore, Aobao is still worthy of preservation and research.

Modeling of Assembly Deviation with Considering the Actual Working Condition

Wenhui Zeng,Yunqing Rao 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.5

Generally, it would be more realistic to consider that the components of an assembly are flexible typically undergo some deformations. In addition, with the mobility of the parts, there is normally a wear between the contact surfaces. Ignoring the dynamic working conditions with these deformations and wear could lead to an inaccurate assembly deviation and further affect the performance, reliability and service life of products. This paper proposes modeling of assembly deviation by considering the actual working conditions to obtain the time-variant assembly gap during the service time. First, the dimensional and geometric tolerances of the parts are simulated by Monte Carlo simulation, and the assembly deviation caused by the tolerances is obtained based on modified Unified Jacobian–Torsor model. Second, the deformation of the surfaces of the parts induced by mechanical and thermal loads are calculated by finite element analysis. Third, the wear depth between the contact surfaces is derived by conducting wear tests under the simulating working condition. By integrating the deformations and wear into tolerance analysis model, the final assembly deviation is constructed by considering the actual working conditions. Finally, the proposed model is applied to the blade bearing of controllable pitch propeller (CPP) for determining the effect of the actual working conditions on its service life.

Genomic Analysis of the Xanthoria elegans and Polyketide Synthase Gene Mining Based on the Whole Genome

Xiaolong Yuan,Yunqing L,Ting Luo,Wei Bi,Jiaojun Yu,Yi Wang 한국균학회 2023 Mycobiology Vol.51 No.1

Xanthoria elegans is a lichen symbiosis, that inhabits extreme environments and can absorb UV-B. We reported the de novo sequencing and assembly of X. elegans genome. The whole genome was approximately 44.63 Mb, with a GC content of 40.69%. Genome assembly gen- erated 207 scaffolds with an N50 length of 563,100 bp, N90 length of 122,672 bp. The gen- ome comprised 9,581 genes, some encoded enzymes involved in the secondary metabolism such as terpene, polyketides. To further understand the UV-B absorbing and adaptability to extreme environments mechanisms of X. elegans, we searched the secondary metabolites genes and gene-cluster from the genome using genome-mining and bioinformatics analysis. The results revealed that 7 NR-PKSs, 12 HR-PKSs and 2 hybrid PKS-PKSs from X. elegans were isolated, they belong to Type I PKS (T1PKS) according to the domain architecture; phylogen- etic analysis and BGCs comparison linked the putative products to two NR-PKSs and three HR-PKSs, the putative products of two NR-PKSs were emodin xanthrone (most likely parietin) and mycophelonic acid, the putative products of three HR-PKSs were soppilines, (þ)-asperlin and macrolactone brefeldin A, respectively. 5 PKSs from X. elegans build a correlation between the SMs carbon skeleton and PKS genes based on the domain architecture, phylo- genetic and BGC comparison. Although the function of 16 PKSs remains unclear, the findings emphasize that the genes from X. elegans represent an unexploited source of novel polyke- tide and utilization of lichen gene resources.

Richardson extrapolation and defect correction of mixed finite element methods for elliptic optimal control problems

Yanping Chen,Yunqing Huang,Tianliang Hou 대한수학회 2012 대한수학회지 Vol.49 No.3

In this paper asymptotic error expansions for mixed finite element approximations to a class of second order elliptic optimal control problems are derived under rectangular meshes, and the Richardson extrapolation of two different schemes and interpolation defect correction can be applied to increase the accuracy of the approximations. As a by-product, we illustrate that all the approximations of higher accuracy can be used to form a class of a posteriori error estimators of the mixed finite element method for optimal control problems.

RICHARDSON EXTRAPOLATION AND DEFECT CORRECTION OF MIXED FINITE ELEMENT METHODS FOR ELLIPTIC OPTIMAL CONTROL PROBLEMS

Chen, Yanping,Huang, Yunqing,Hou, Tianliang Korean Mathematical Society 2012 대한수학회지 Vol.49 No.3

In this paper asymptotic error expansions for mixed finite element approximations to a class of second order elliptic optimal control problems are derived under rectangular meshes, and the Richardson extrapolation of two different schemes and interpolation defect correction can be applied to increase the accuracy of the approximations. As a by-product, we illustrate that all the approximations of higher accuracy can be used to form a class of a posteriori error estimators of the mixed finite element method for optimal control problems.

SPECTRAL-COLLOCATION METHOD FOR FRACTIONAL FREDHOLM INTEGRO-DIFFERENTIAL EQUATIONS

Yin Yang,Yanping Chen,Yunqing Huang 대한수학회 2014 대한수학회지 Vol.51 No.1

We propose and analyze a spectral Jacobi-collocation approx- imation for fractional order integro-differential equations of Fredholm- Volterra type. The fractional derivative is described in the Caputo sense. We provide a rigorous error analysis for the collection method, which shows that the errors of the approximate solution decay exponentially in L ∞ norm and weighted L²-norm. The numerical examples are given to illustrate the theoretical results.

First-principles study on doping effect of Sn in BiF3 as cathode materials for Li-ion battery

Zhenhua Yang,Shuncheng Tan,Yunqing Huang 한국물리학회 2016 Current Applied Physics Vol.16 No.1

First-principles calculations were carried out to investigate the structural relaxation, formation energy, electronic structure and electrochemical properties of Sn-doped BiF3. When Sn was doped into BiF3, two common oxidation states of Sn, þ2 and þ4, were considered. In addition, some typical neutral and charge defects (Sn0 Bi,Sn1 Bi ,Sn1þ Bi ,V2 Bi1 V2 Bi2 and V0 F ) were discussed in detail. Calculated formation energies indicate that Sn4þ ion is much easier to dope into BiF3 than Sn2þ ion. When Fermi level lies at the bottom of conduction band, Sn1/32Bi30/32F3 with V2 Bi1 (Bi vacancy defect) induced by Sn4þ ion doping has the most stable structure under the rich-F growth condition. Here, DmSn, DmBi and DmF are 13.18 eV,9.71 eV and 0, respectively. What's more, the crystal structure, electronic structure and electrochemical properties of Sn1/32Bi30/32F3 with V2 Bi1 were further investigated. It is found that the crystal volume of Sn1/32Bi30/32F3 with V2 Bi1 is larger than that of pure BiF3 because the length of BieF bond around V2 Bi1 in the Sn1/32Bi30/ 32F3 becomes much longer relative to the length of BieF bond in the pure BiF3. Besides, the calculated band gap of Sn1/32Bi30/32F3 with V2 Bi1 is 2.70 eV, which is smaller than that of pure BiF3. Furthermore, Sn1/ 32Bi30/32F3 with V2 Bi1 has better theoretical voltage and theoretical capacity than pure BiF3.

First-principles study on the doping effects of Al in a-MnO2

Zhenhua Yang,Xianyou Wang,Yunqing Huang 한국물리학회 2015 Current Applied Physics Vol.15 No.11

In this paper, first-principles calculations have been implemented to study the structural relaxation, formation energies and electronic structure of Al doped a-MnO2. Both Al insertion and Al substitution reactions in the a-MnO2 were considered. Calculated formation energies indicate that Mn atom is easier to be displaced by Al atom under the O-rich growth condition compared with Al insertion reaction. Besides, it can be found that Al doping can afford acceptor impurity level which can accommodate electrons, thus contributing to the improvement of conductivity of a-MnO2. The conductivity of a-MnO2 is gradually improved with the increasing doping concentration of Al, and Al0.0417Mn0.9583O2 exhibits the best conductivity. Lastly, the electronic structure of Al0.0417Mn0.9583O2 was further investigated by analysis of total charge density and Bader charge. It is clear that Al doping can afford more electrons for a-MnO2, which also contributes to improvement of its conductivity.

An Optimization Algorithm for Solving High-Dimensional Complex Functions Based on a Multipopulation Cooperative Bare-Bones Particle Swarm

Liu Cong,Liu Yunqing,Wu Tong,Yan Fei,Zhang Qiong 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

The particle swarm optimization (PSO) algorithm can easily become trapped in a local optimum when the objective function to be optimized is high-dimensional and complex. A multipopulation, cooperative, bare-bones particle swarm optimization (MCBBPSO) algorithm is proposed to solve this problem. In MCBBPSO, three types of parallel cooperative learning populations are used to optimize the objective function. By adding disturbance factors and adopting an elite reverse learning strategy, the optimization ability of the algorithm is increased. Through the “mirror wall” method, the cross-boundary particles are processed to reduce the loss of particle resources. Experiments using the CEC2013 standard test functions demonstrate the convergence accuracy and speed of the algorithm on high-dimensional and complex objective functions. Finally, MCBBPSO is applied to perform parameter optimization in support vector regression (SVR), and short-term wind speeds are then predicted using the optimized SVR approach to reduce resource consumption in a power grid.