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Structure and Stacking Faults in Sr₂Be₂B₂O7 Crystal
X. Y. Meng,X. H. Wen,G. L. Liu 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4
Inspired by the successful study on the structure instability of Na₂Al₂B₂O7 (NABO), we extend our interest to a theoretical study, by using density functional theory, on the crystal structures of Sr₂Be₂B₂O7 (SBBO), which possess pretty much the same [M₂B₂O7]∞ (M = Be, Al) double layers as those of the NABO crystal. The energy differences of the SBBO structural variants are found to be so slight that stacking faults could readily occur in the crystal. We propose that different phases may coexist in the same SBBO crystallite, forming domain structure similar to those of NABO which were found by using single-crystal X-ray diffraction. The structural stability of SBBO is closely related to the cohesion forces between [Be₂B₂O7 ∞ layers. A similar structure analysis can be extended to the SBBO isomorphism. Inspired by the successful study on the structure instability of Na₂Al₂B₂O7 (NABO), we extend our interest to a theoretical study, by using density functional theory, on the crystal structures of Sr₂Be₂B₂O7 (SBBO), which possess pretty much the same [M₂B₂O7]∞ (M = Be, Al) double layers as those of the NABO crystal. The energy differences of the SBBO structural variants are found to be so slight that stacking faults could readily occur in the crystal. We propose that different phases may coexist in the same SBBO crystallite, forming domain structure similar to those of NABO which were found by using single-crystal X-ray diffraction. The structural stability of SBBO is closely related to the cohesion forces between [Be₂B₂O7 ∞ layers. A similar structure analysis can be extended to the SBBO isomorphism.
R&D Status of High-current Accelerators at IFP
J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.
Neuregulin 1 regulates pyramidal neuron activity via ErbB4 in parvalbumin-positive interneurons
Wen, L.,Lu, Y.-S.,Zhu, X.-H.,Li, X.-M.,Woo, R.-S.,Chen, Y.-J.,Yin, D.-M.,Lai, C.,Terry, A.V.,Vazdarjanova, A. National Academy of Sciences 2010 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.107 No.3
X.Z. Yang,L. Wen 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4
In this paper, we employ a novel method of field activated and pressure assisted synthesis to prepare ultra-hard, superabrasives from the elemental constituents (aluminum, magnesium and boron). Under the conditions in the present work, the simultaneous synthesis and consolidation of such intermetallic compounds can be achieved at 1500 o C with a pressure of 60 MPa. The prepared compounds show a hardness of 32.5 GPa, which is consistent with the hardness of AlMgB14 prepared by hot uniaxial pressing, and the average density was 2.62 g/cm3 . Furthermore, it is found that such compounds are not produced from the elemental constituents in the present condition.
Growth Performance, Carcass Composition and Meat Quality of Jiulong-yak (Bos grunniens)
Zi, X.D.,Zhong, G.H.,Wen, Y.L.,Zhong, J.C.,Liu, C.L.,Ni, Y.A.,Yezi, Y.H.,Ashi, M.G. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.3
Estimated liveweights, carcass characteristics, the proximate composition and amino-acid composition of the whole rib cut of the 10th/12th thoracic vertebrae have been determined for Jiulong-yak. The animal grows rapidly up to puberty at 2-3 years of age. At those ages, females reached 143.0$\pm$34.7 kg and 184.0$\pm$30.8 kg (SD) respectively, which was 60 to 80% of their mature weight at 6 to 7 yr old, then the rate of growth significantly slowed down. Males continued to rapidly increase body weight until an older age possibly due to the selection procedures. Animals included 20 males aged from 2.5 to 6.5 yr, seven females aged of 4.5 yr and 11 steers aged of 4.5-5.5 yr were slaughtered for carcass determination and chemical analysis of meat samples. Dressing-out percentage and ribeye area ranged from 48.53-55.04% and 48.02-68.56 $cm^2$ respectively, both of which differed by age and sex. Yak meat is scarlet in color and intramuscular marbling is poor. The 10th/12th rib-cut contained 24.99-31.93% dry matter; 19.98-22.58% protein; 2.52-10.86% fat and 0.93-1.00% ash. Meat from females and steers contained a higher percentage of fat than those from bulls. The pH of M. Longissimus dorsi measured at 24 h post-mortem ranged from 5.84-6.11. Amino acid composition was similar to that for other red meat, except for a lower content of methionine (1.26 g/100 g meat). The results indicated that yak meat can make a valuable contribution to the diets for the highlanders.
EFFECTS OF HEAT TREATMENT ON COEFFINIENT OF THERMAL EXPANSION OF SQUEEZE CAST SiCw/AL COMPOSITE
Geng, L.,Wen, B.X.,Yao, C.K. 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.2
The SiCw/6061Al Composite was fabricated by using ${\beta}-SiC$ whisker as the reinforcement and the commercial 6061 aluminum alloy as the matrix. Squeeze casting technique was for fabricating the composite with the whisker volume fraction of 31%. The SiCw/6061Al compsites were divided into three groups : the first is in as cast state ; the second is in T6 state ; and the third is in deep cooled state. The coefficient of thermal expansion (CTE) of the 6061Al and SiCw/6061Al composites in different states were measured at temperatures rom $100^{\circ}C$ to $500^{\circ}C$. The experimental results showed that the coefficient of thermal expansion of both 6061Al and SiCw/6061Al composites increases with increasing temperature. In the lower temperature range, the coefficient of thermal expansion of the SiCw/6061Al composite is obviously lower than that of the 6061Al. but because of the higher rate of the increment of CTE of the composite, the value of CTE of the composite, the value CTE of the compostie becomes almost equal to that of the 6061Al after the temperature is higher than $400^{\circ}C$. The results also indicated that, at th lower temperature range, the CTE of the T6 state composite is lower than that of the as-cast composite, and the deep cooled composite showed the lowes CTE.
Experimental study on fabrication and evaluation of a micro-scale shaft grinding tool
Y. D. Gong,X. L. Wen,J. Cheng,G. Q. Yin,C. Wang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.3
This paper presents a micro-grinding experiment on AISI 1020 steel and Ti-6Al-4V to study micro-grinding principle and the changerule of the force and surface with different grinding parameters. A novel micro shaft grinding tool is fabricated by cold sprayed withCBN grains, the manufacturing is carried out on a desktop micro machine developed by NEU. Influences caused by particle size on surfacequality has been discussed, it has been tested that low surface roughness could be achieved on 3000 particle size of micro shaftgrinding tool, the roughness of AISI 1020 steel accomplished in the experiment is about 0.086 μm. Measured micro-grinding force of Ti-6Al-4V decreases with the increasing spindle speed and the decreasing cutting depth. The surface roughness decreases with the increasingspindle speed and the decreasing feed rate. The minimum surface roughness is 325 nm with the spindle speed of 48000 r/min and thefeed rate of 20 μm/s.