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X. J. Chen,J. C. Xu,H. X. Jin,D. F. Jin,B. Hong,H. L. Ge,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5
In this paper, ordered mesoporous SBA-15 silica was synthesized by the hydrothermal method, and then a series of CoFe2O4/SBA-15 nanocomposites were synthesized by a facile impregnation method. X-ray diffraction and N2 adsorption–desorption isotherms were used to characterize the microstructure and morphology of SBA-15 and CoFe2O4/SBA-15 nanocomposites. CoFe2O4 nanoparticles presented spinel phase structure and existed in the mesopores of SBA-15. The magnetic response of CoFe2O4/SBA-15 nanocomposites was characterized with vibrating sample magnetometer (VSM). The adsorption efficiency of CoFe2O4/SBA-15 nanocomposites for methylene blue increased firstly with the increasing CoFe2O4 content, and then decreased. Sample-2 (SBA-15: CoFe2O4 = 1: 0.1 in the precursor) not only presented the best adsorptive performance, but also could be separated and retrieved effectively by magnetic separation technique.
Microwave Absorption and Magnetic Properties of Cobalt Ferrites/Carbon Nanotubes Nanocomposites
B. B. Zhang,P. F. Wang,J. C. Xu,Y. B. Han,H. X. Jin,D. F. Jin,X. L. Peng,B. Hong,J. Li,J. Gong,H. L. Ge,Z. W. Zhu,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5
Owing to the unique microstructure and the excellent dielectric properties, carbon nanotubes(CNTs) were decorated with CoFe2O4 nanoparticles to synthesize the CoFe2O4/CNTs nanocomposites by the solvothermal method. The phase structure, morphology, magnetic properties and microwave absorption performance of the as-prepared CoFe2O4/CNTs were characterized and discussed by X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). All results indicated that the diameter of CoFe2O4 nanoparticles decorating on the surface of CNTs increased with the solvothermal temperature. CoFe2O4/CNTs prepared at 180℃, 200℃ and 220℃ exhibited superparamagnetism, while the other samples presented ferromagnetism at room temperature. And with the increasing solvothermal temperature, the saturation magnetization and coercivity increased up to 72 emu/g and 2000 Oe for the sample prepared at 260℃ (S-26). And the reflection loss of CoFe2O4/CNTs nanocomposites increased with the solvothermal temperature up to -15.7 dB for S-26 with the bandwidth of 2.5 GHz.
C. C. Li,K. Li,J. Li,D. L. Mo,R. F. Xu,G. H. Chen,Y. Z. Qiangba,S. L. Ji,X. H. Tang,B. Fan,M. J. Zhu,T. A. Xiong,X. Guan,B. Liu 아세아·태평양축산학회 2006 Animal Bioscience Vol.19 No.2
A 2,656 bp fragment of chicken ghrelin gene was cloned and SNPs were detected by PCR-RFLP and Allele Specific PCR (ASP) in 12 Chinese indigenous chicken breeds and a commercial chicken population. The results showed that there were 23 base variations and an amino acid change (Gln->Arg) in cloned chicken ghrelin gene. Three SNPs were confirmed in 13 populations and associations between this gene and growth traits of Tibetan chicken (TC) and Recessive White chicken (RW) were investigated. The results of haplotype analysis revealed that 26 haplotype genotypes were composed of eight haplotypes. The results of x2 tests indicated that there were significant differences between genotypes or haplotype genotype frequencies in some of the breeds or sexes at 0.05 or 0.01 levels. The results of ANOVA revealed that there were significant differences between genotypes or haplotype genotypes on some growth traits of TC and RW chicken breeds at 0.05 or 0.01 levels. Multiple comparisons showed that there were significant associations between genotype CT at site 71 and some growth traits of two chicken breeds and between genotype AG at site 1,215 and body weight at 16 wk of two chicken breeds, and there was a significant association between haplotype genotype CAA/CAG and body weight and shank girth at 16 wk of two chicken breeds.
Studies on the Genetic Relationships of Sheep Populations from East and South of Central Asia
Sun, W.,Chang, H.,Yang, Z.P.,Geng, R.Q.,Lu, S.X.,Chang, G.B.,Xu, W.,Wang, H.Y.,Ren, Z.J.,Tsunoda, K. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.10
Hu sheep was sampled randomly from Huzhou city, Zhejiang province, China. Of the 11 genetic markers from the blood examined by starch-gel and cellulose acetate electrophoresis, polymorphisms in Hu sheep were found for 10 loci, i.e. post-albumin (Po), transferring (Tf), alkaline phosphatase (Alp), leucine aminopeptidase (Lap), arylesterase (Ary-Es), hemoglobin-$\beta$ (Hb-$\beta$)、Xprotein(X-p), carbonic anhydrase (CA), catalase (Cat) and lysine (Ly). The same data except for Po locus were collected from another 14 sheep breeds from China and other countries, in order to ascertain their genetic relationships with one another and with the Hu sheep. The sheep populations from the east and south of Central Asia can be classified into three genetic groups: 'Mongolian sheep', 'South Asian sheep' and 'European sheep'. The Hu sheep belong to the 'Mongolian sheep' group.
Sound Absorption Performance of Highly Porous Stainless Steel Foam with Reticular Structure
X. B. Xu,P. S. Liu,G. F. Chen,C. P. Li 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
There have been some previous studies on the acoustic properties of metal foams, with the main relevant works focusedon the aluminum foam, but quite fewer on the metal foams of non-aluminum species. Such research, especially, has not yetbeen found on the stainless steel foam, of which the pore-structure related parameters and the morphology are quite differentfrom the aluminum foam. The present work provides the investigations on the sound absorption performance of the 304stainless steel foam and its composite structure. A sort of three-dimensional reticular stainless steel foam was successfullyprepared, with the average pore size of about 1.8 mm and the porosity of about 93.7%. The sound absorption performancewas investigated at 200–6300 Hz for this foam and at 2500–4000 Hz for its composite structures. The results show the wholeabsorption performance of the sample can be significantly improved by introducing an air gap, and further improved withintroduction of both the gap and a perforated plate. It was found that when the thickness of the gap increased (from 3.5 to17.5 mm), the resultant change of the resonance frequency of the sample could lead to a decrease of the absorption coefficientat a certain frequency range, and the total absorption efficiency could be significantly increased.
Low-temperature catalytic combustion of benzene over Ni–Mn/CeO2/cordierite catalysts
B. Li,Q. Huang,X.K. Yan,X.L. Xu,Y. Qiu,B. Yang,Y.W. Chen,S.M. Zhu,S.B. Shen 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
The catalytic combustion of benzene over a Ni–Mn mixed oxide supported on cordierite coated with CeO2 was investigated. The catalysts were prepared using a sol–gel method and characterized using BET, H2-TPR, XRD, SEM and TEM. The catalysts calcined at 500 ℃ for 7 h with a Ni/Mn molar ratio of 1 exhibited the highest catalytic activity. When the concentration of benzene was 4.8 g/m3 and the GHSV was 15,000 h-1, the conversion was 94.3% at 300 ℃. These results were primarily attributed to the catalyst structure and the synergistic activity of the NiMnO3 perovskite and crystalline CeO2.
NUMERICAL ANALYSIS OF HOMOGENEOUS MIXTURE FORMATION FOR A DIRECT INJECTION LIQUID LPG ENGINE
B. Y. XU,X. C. ZHANG,J. XU,Y. L. QI,S. L. CAI 한국자동차공학회 2013 International journal of automotive technology Vol.14 No.6
A method to form a homogeneous mixture using low pressure direct injection of liquid phase LPG, pent-roof combustion chamber, flat-top piston and center-located injector layout is presented. To validate the method, the mixture formation processes in the cylinder were investigated using the CFD code. The effect of different injection timing and engine loads on the mixture formation processes were researched. The simulated results showed that, the intake tumble for high load conditions or the inclined intake swirl for part load conditions would break into small-scale vortex (turbulence) near the end of compression stroke, which enhanced the homogeneous mixture formation. The results also showed that if the liquid phase LPG was injected at 60-80oCA ATDC in intake stroke even at different loads, the homogeneous mixture would be formed under any engine load conditions.
Li, X.B.,Rahman, Md.M.,Xu, G.R.,Lee, J.J. Pergamon Press 2015 ELECTROCHIMICA ACTA Vol.173 No.-
A highly sensitive and selective electrochemical method based on a poly(chromotrope 2B)-modified anodized glassy carbon electrode (PCHAGCE) was developed for the determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA). The PCHAGCE sensor exhibited excellent electron-mediating behavior towards the oxidation of DA in 0.1M phosphate buffer solution (PBS) (pH7.0). It was found that the electrocatalytic activity was significantly dependent on the charge status and molecular structure of the target molecules. Differential pulse voltammetry (DPV) measurements revealed oxidation signals for DA, UA, and AA that were well-resolved into three distinct peaks with AA-DA, DA-UA, and AA-UA peak potential separations (ΔE<SUB>p</SUB>) of 172, 132, and 304mV, respectively. A detection limit of 0.04+/-0.001μM (S/N=3) and a quantification limit (S/N=10) of 0.149+/-0.03μM were obtained for DA sensing in a linear range of 1 to 40μM in PBS (pH7.0) with a very high sensitivity of 1.522+/-0.032μA.μM<SUP>-1</SUP>. The DA concentrations in human urine samples were also successfully determined with recoveries of 94.0-98.0%. This approach provides a simple, easy, sensitive, and selective method to detect DA in the presence of AA and UA.
Steady-state Operational Strategies of UPFC in the KEPCO Transmission System
Chang, B.H.,Choo, J.B.,Xu, X.K.,Lam, B.P. The Korean Institute of Electrical Engineers 2003 KIEE International Transactions on Power Engineeri Vol.a3 No.3
This paper presents a study performed to investigate the steady-state operational strategies of UPFCs in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points under normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFCs in the system, assessing the effectiveness of UPFCs by contingency analysis, and introducing optimal corrective actions for removing voltage problems caused by contingencies. The paper describes analytical tools, models and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.