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The Influence of Precipitated Phase in Al-4%Cu Alloy under High Magnetic Field
Jiang Jun,HyunJun Lee,Qi Min,WonJo Park 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Nonferrous metals have a very important position in industry. At present, parts of shipbuilding, automobile, and aircraft etc. are designed and manufactured accurately, simultaneity need light-weight and high-strength. Aluminum copper alloys are one kind of typical precipitation hardening alloy which has been widely used. It is interesting to investigate transformation behavior of precipitated phase in such kind of alloys under high magnetic field. Transformation of materials under high magnetic field is many different compared with conventional condition. The author prepared the Al-4%Cu alloy.
Jiang Jun,Qi Min,Won-Jo Park 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Transformation of materials under high magnetic field is much different compared with conventional condition. There is big significant in materials science investigating transformation behavior of materials under high magnetic field. Aluminium copper alloys are one kind of typical precipitation hardening alloy which has been widely used in industry. It is interesting to investigate transformation behavior of such kind of alloys under high magnetic field. The author prepared the Al-4%Cu alloy using crucible electrical resistance furnace in order to further the research of the Al-Cu binary alloy. The analysis techniques such as optical microscopy (OM), Vickers micro-hardness, and X-ray diffraction and transmission electron microscopy (TEM) were employed in this dissertation. Firstly the Al-4%Cu alloys which annealed at 180 ℃ are briefly studies. Then the precipitating behavior of second phases in specimens that aged with and without high magnetic field and through cryogenic treatment were analyzed and discussed mainly based on the comparison of experimental results of Vickers micro-hardness testing and XRD analysis respectively.
A study on the new high strength casting Al-Cn alloy by heat treatment and structure property
Jiang Jun,HyunJun Lee,SunChul Huh,WonJo Park 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
Aging and solid-solution are main methods to strengthen metal, and their optimal strengthening temperature and time are more and more drew attention to study. Al-Cu alloys are one kind of typical precipitation hardening alloy, and high strength casting Al-Cu alloy has been widely used in industry. In this study the authors use heat treatment and aging to strengthen the alloy, and then the analysis techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical metallographic examination(OM), metallographic analysis, fracture analysis and electron diffraction were employed in this dissertation.
Jun Peng,Qian Wang,Jin Wang,Jun Yang,Taijun Jiang,Guangsheng Zeng 한국고분자학회 2022 Macromolecular Research Vol.30 No.11
Cardo containing phenoxy and -CF3 derivate diamine was synthesized, and further it was polymerized with 3,3',4,4'-biphenyl tetracarboxylic dianhydride to prepare polyetherimide containing Cardo group. The transmittance of the prepared polymer increased from 82% to 88% and the dielectric constant decreased from 2.91 to 2.83 with a slight decline in thermal and mechanical performance when -CF3 was introduced. The molecular simulation in terms of charge distribution, electric potential energy, chain stiffness and aggregation state revealed that -CF3 could restrain charge transfer and decrease the unit dipole moment and polarization for its larger volume. The optical and dielectric performance was significantly enhanced, but the thermal and mechanical performance decreased slightly when the -CF3 group was introduced. The glass transition temperature of the polymer declined from 329℃ to 311℃. The investigation conducted in this paper can offer valuable reference to the optimization and development of synthesis and comprehensive performance of polyimide.
A New ent-Kaurane type Diterpenoid Glycoside from Inula japonica Thunb
Jiang Jiang Qin,Jia Xian Zhu,Wei Dong Zhang1,2,Yan Zhu,Jian Jun Fu,Xiao Hua Liu,Hui Zi Jin 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.10
A new ent-kaurane type diterpenoid glycoside, 17-O-β-D-glucopyranosyl-16α-ent-kauran-19-oic acid (1), together with 17-hydroxy-16α-ent-kauran-19-oic acid (2), 16α,17-dihydroxyl-ent-kauran-19-oic acid (3), and 16α-hydroxy-17-acetoxy-ent- kauran-19-oic acid (4) were isolated from the aerial parts of Inula japonica Thunb. The structure of 1 was determined mainly by use of 1D and 2D NMR spectroscopic techniques including HSQC, 1H-1H COSY, HMBC, and NOESY. In addition, 4 exhibited significant inhibitory activity on NO production in LPS-stimulated RAW264.7 cells with IC50 value of 14.3 μg/mL.
Jun Jiang,Qing-Ming Chen,Xiang Liu 한국물리학회 2018 Current Applied Physics Vol.18 No.2
The electronic structure and optical properties of La0.75Sr0.25MnO3-σ (LSMO3-σ) materials with 1 × 1 × 4 orthorhombic perovskite structure were performed by first-principles calculation. The structural changing of LSMO3 (ideal structure, σ = 0) was not obvious under generalized gradient approximation (GGA) and GGA + U arithmetic. On the contrary, the structural changing of LSMO3-σ (σ = 0.25, with oxygen vacancies defects in the z = 0, c/8, c/6, c/4, and c/2) with GGA + U were more obvious than the result of ideal. This structural distortion induced distinct changing in density of states (DOS) for LSMO3-σ materials. Oxygen vacancy defects caused a shift of the total density of states (TDOS) features toward low binding energies and LSMO3-σ keep half-metal properties as well as LSMO3 ideal structure. In addition, the hybridization between the Mn-eg and O-2p orbital was weakened and the partial density of states (PDOS) of Mn indicated a strong d-d orbital interaction. By the result of oxygen vacancy formation energy, oxygen vacancy defects can be more easily formed in La-O layers (z = 0 and c/6) to compare with other layers (z = c/8, c/4 and c/2). The calculation result of optical properties suggested that the ideal LSMO could be produced strong absorption in the range of ultraviolet and visible light, while the LSMO3-σ with oxygen vacancies defects were presented weak absorption in the range of visible light.
Organization process of the hierarchical structures in microbially synthesized polyhydroxyalkanoates
Jun Xu,Bao-Hua Guo,Qiong Wu,Jin-Chun Chen,Guo-Qiang Chen,Jian-Jun Zhou,Yong Jiang,Lin Li 한국물리학회 2007 Current Applied Physics Vol.7 No.s1
cess of the high-order structures in biomaterials. Real-time Fourier transform infrared spectroscopy and optical microscopy demon-strated that helical segments formed along with the spherulite growth. Atomic force microscopy revealed the details of growth,twisting and branching of lamellar crystals. Cooperative packing of these twisting lamellae led to regular banded spherulites observedunder polarized light microscopy. Real-time observation on the crystallization process provided richer information than the characterization of the final structures; consequently, it provides deeper insight into the organization mechanism of the hierarchical structures.
A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts
Jiang, Jun,Xu, Tianhao,Li, Yaping,Lei, Xiaodong,Zhang, Hui,Evans, D.G.,Sun, Xiaoming,Duan, Xue Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about $100^{\circ}C$ and activation process is essentially complete below $145^{\circ}C$. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature ($170^{\circ}C$) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.