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91.
运用基于壳模型的分子动力学方法研究了BaTiO3铁电体中的辐射位移效应.采用O原子作为初级击出原子,模拟了当初级击出原子能量为1 keV时体系内缺陷的产生和演化.模拟结果表明,当入射方向为[001]时,体系内产生的缺陷最多.在所有缺陷中,以O缺陷的含量为最高,达80%以上.同时,这些缺陷的产生并不显著改变体系的自发极化强度,对体系的极化翻转过程也基本没有影响.在外电场作用下,观察到了显著的缺陷迁移.
关键词:
分子动力学
3铁电体')" href="#">BaTiO3铁电体
辐射位移效应 相似文献
92.
Jeng-Jong Hwang Tzu-Chen Yen Bor-Tsung Hsieh Gann Ting 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(3):581-587
The evaluation of the pharmacokinetics of pure, beta radiopharmaceuticals is not possible with scintigraphy. Both whole-body
autoradiography (WBAR) and Packard Instantimager, a device for rapid imaging, were used to study the whole body distribution
of γ- and β-emitting radionuclides (99mTc-MDP,99mTc-sulfur colloid, or188Re-HEDP), and results obtained from both methods were compared. The biodistribution of99mTc-MDP and188Re-HEDP were seen mainly in bones including skull, spine, and vertebrae of spine and cardiac and skeletal muscles. The99mTc-sulfur colloid localized in liver, bone marrow, and spleen. The resolution of WBAR is superior than that of Packard Instantimager.
However, the advantage of Packard Instantimager is that rapid imaging within few minutes is possible with it, while WBAR imaging
requires several hours to days. 相似文献
93.
Y Hsieh M Chintala H Mei J Agans J M Brisson K Ng W A Korfmacher 《Rapid communications in mass spectrometry : RCM》2001,15(24):2481-2487
A higher-throughput bioanalytical method based on fast-gradient (1 min run time) high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS) was developed for screen-type analyses of plasma samples from early drug discovery studies in support of exploratory pharmacodynamic studies. The HPLC system equipped with minibore column was interfaced with either atmospheric pressure chemical ionization (APCI) or electrospray (ESI) ionization techniques. The matrix ion suppression effect of both quantitative HPLC/MS/MS analyses was compared using the post-column infusion system. The use of the described methods provided advantages such as a shorter chromatographic region of ion suppression, less solvent consumption and shorter run times in comparison with standard analytical column HPLC/MS/MS methods. The analytical results obtained by both HPLC/MS/MS methods were in good agreement (within 15% of error) and displayed a good correlation with the pharmacodynamic outcome. 相似文献
94.
(WO3)0.15(BiO1.5)0.85 exhibits a tetragonal structure derived from the fluorite subcell. The electrical conductivity of (WO3)0.15(BiO1.5)0.85 is lower than that of Y2O3-doped Bi2O3. The structure and electrical conductivity of samples formulated as (YO1.5)
x
(WO3)0.15(BiO1.5)0.85-
x
(x = 0.1, 0.2, 0.3, and 0.4) were investigated. The as-sintered (YO1.5)0.1(WO3)0.15(BiO1.5)0.75 exhibited a single cubic structure that is isostructural with δ-Bi2O3. For x = 0.2, 0.3, and 0.4, the as-sintered samples consisted of a cubic fluorite structure and rhombohedral Y6WO12. After heat treatment at 600 °C for 200 h, the cubic structures are stable for x = 0.1, 0.3, and 0.4. A transformation from cubic to rhombohedral phase after heat treatment at 600 °C for 200 h was observed
in the sample originally formulated as (YO1.5)0.2(WO3)0.15(BiO1.5)0.65. 相似文献
95.
The methanolysis of 2‐(2‐aryl ethynyl)benzonitriles is accelerated when the polar aprotic solvents are added, which could enhance the 6‐endo pathway and give isoquinolones, though the 5‐exo pathway is occupied mostly. The yields of products would also be in creased. 相似文献
96.
Polyurethanes (PU) based on poly(butylene adipate) [PU(PBA)] and poly(oxypropylene) [PU(PPG)] polyols have bean introduced into the diglycidyl ether of bisphenol A (epoxy) to form interpenetrating polymer networks (IPNs) with a PU-grafted epoxy structure (graft-IPNs). The tensile strength in both PU(PPG)/epoxy and PU(PBA)/epoxy systems increases with increasing PU content. Maximum values emerge at PU/epoxy ratios between 19/81 and 27/73. This is explained as a result of the presence of the graft structure, which leads to more intimate interpenetration between the PU and epoxy in the graft-IPNs. Dynamic mechanical analysis (DMA) indicates that the PU introduced can be incorporated in either the α or β transition domain of the epoxy. The tensile strength of the resulting graft-IPNs shows a significant improvement as the PU is incorporated in the α transition domain of the epoxy. It is also noted that suitable amounts of PU incorporated in both the α and β transition domains of epoxy can increase the tensile strength of the IPNs, while excessive amounts of PU introduced into both α or β transition domains tend to decrease the tensile strength of the graft-IPNs. 相似文献
97.
Chiung‐Feng Liao Bar‐Yuan Hsieh Yun Chen 《Journal of polymer science. Part A, Polymer chemistry》2009,47(1):149-160
Copolyfluorenes PFG1~PFG4 slightly doped with 0.006–0.5 mol % of 2,5‐dihexyloxy‐1,4‐bis(2‐phenyl‐2‐cyanovinyl)benzene (green chromophore) were synthesized by the Suzuki coupling reaction to be evaluated as hosts for white‐light electroluminescent (EL) devices. Their optical, thermal and electrochemical properties were almost identical to those of polyfluorene ( PF ) due to minimal chromophore content. However, the electroluminescent (EL) spectra of the PFGn were very different from photoluminescence spectra in film state. Relative intensity of green emission (ca. 521 nm) in EL spectra are much stronger than those in PL spectra, which can be attributed to charges trapping in the chromophores due to its narrow band gap (Eg ≈ 2.56 eV). The performance of EL devices [ITO/PEDOT:PSS/polymer/Ca (50 nm)/Al (100 nm)] were improved with an increase in chromophore content. The PFG4 device revealed the best performance (6790 cd/m2, 1.69 cd/A), and the PFG1 and PFG2 devices exhibited comparable intensity in blue and green emissions. Blend EL devices were fabricated by using the PFGn as the hosts and a red iridium complex [Ir(piq)2(acac)] as dopant. By controlling the amount of the iridium complex, the white‐light emitting device was achieved with PFG2 , with maximum brightness and CIE coordinate being 4120 cd/m2 and (0.31, 0.28), respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 149–160, 2009 相似文献
98.
Sigrid Blömeke Lynn Paine Richard T. Houang Feng-Jui Hsieh William H. Schmidt M. Teresa Tatto Kiril Bankov Tenoch Cedilllo Leland Cogan Shin Il Han Marcella Santillan John Schwille 《ZDM》2008,40(5):749-762
The study "Mathematics Teaching in the 21st Century (MT21)" focuses beyond others on the measurement of teachers’ general pedagogical knowledge (GPK). GPK is regarded as a latent construct embedded in a larger theory of teachers’ professional competence. It is laid out how GPK was defined and operationalized. As part of an international comparison GPK was measured with several complex vignettes. In the present paper, the results of future mathematics teachers’ knowledge from four countries (Germany, South Korea, Taiwan, and the US) with very different teacher-education systems are presented. Significant and relevant differences between the four countries as well as between future teachers at the beginning and at the end of teacher education were found. The results are discussed with reference to cultural discourses about teacher education. 相似文献
99.
Bor-Tsung Hsieh Wan-Yu Lin Tsai-Yueh Luo Kai-Yuan Cheng 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(3):569-573
Twenty clinical scale alumina-based 188W/188Re generators and carrier-free 188Re has been produced at the Institute of Nuclear Energy Research (INER-Taiwan) for over ten years. 2845.6 GBq (76.9 Ci) of
188Re-perrhenate solution has been eluted from generators during the past ten years. We have used the harvesting 188Re solution for labeling radiopharmaceuticals, such as 188Re-HEDP, 188Re-MDP, 188Re-microsphere, 188Re-lipiodol, and 188Re-sulfur colloid, etc. The average eluting yield of 188Re is 78.6±5.8% that was investigated at 1115 harvesting times from 20 generators. Each generator can be used more than six
months but the Millipore needs to be changed every two months for smooth harvesting and high yield of 188Re solution. 相似文献
100.
Bar‐Yuan Hsieh Kun‐Ming Yeh Yun Chen 《Journal of polymer science. Part A, Polymer chemistry》2005,43(21):5009-5022
New copoly(aryl ether)s ( P1 – P3 ) containing alternate 2,5‐dihexyloxy‐1,4‐di(m‐ethoxystyryl)benzene ( P1 , P2 ) or 2,5‐dihexyloxy‐1,4‐distyrylbenzene ( P3 ) chromophores and aromatic 1,3,4‐oxadiazole ( P1 ) or 3,3″‐terphenyldicarbonitrile ( P2 , P3 ) segments were prepared by Horner reaction ( P1 and P2 ) or nucleophilic displacement reaction ( P3 ). They are basically amorphous materials with 5% weight‐loss temperature above 410 °C. Their absorption, photoluminescence spectra, and quantum yields are dependent on the composition of the isolated fluorophores. The emissions are exclusively dominated by 1,4‐distyrylbenzene segments via excitation energy transfer from electron‐transporting 1,3,4‐oxadiazole ( P1 ) or 3,3″‐terphenyldicarbonitrile ( P2 , P3 ) chromophores. The HOMO and LUMO energy levels have been estimated from their cyclic voltammograms, and the observations confirm that oxidation and reduction start from the emitting 1,4‐distyrylbenzene and electron‐transporting segments, respectively, indicating that both carriers affinity can be enhanced simultaneously. Among the two‐layer PLED devices (ITO/PEDOT/ P1 – P3 /Al), P1 exhibits the best performance with a turn‐on field of 4 × 105 V/cm and a maximum luminance of 225 cd/m2. However, P2 emits green–yellow light (555 nm), owing to the excimer emission. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5009–5022, 2005 相似文献