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101.
102.
Yanfeng Meng Feng Zhang Huidong Gu Jinnan Wang Chun Yuan Zhaoqi Zhang Bensheng Qiu Xiaoming Yang 《Applied magnetic resonance》2011,40(1):105-112
This study was to validate the feasibility of using a magnetic resonance imaging-guidewire (MRIG) for intravascular 3.0 T
MR imaging of deep-seated arterial walls of large animals. The functionality of a 0.032-in. MRIG was evaluated and the signal-to-noise
ratio (SNR) was calculated. Then, MRI of ten iliofemoral arteries of six pigs was acquired by MRIG and surface coil. The difference
in the SNRs of the arterial walls between different coils was compared. Histology examined the potential thermal injuries
of the imaged vessels. The MRIG functioned with the 3.0 T MR scanner. The average SNR of the arterial walls was significantly
higher with the MRIG than with the surface coils (76.22 ± 34.76 vs. 12.63 ± 4.25, P < 0.01). Histology showed no evidence of thermal injuries at the vessel walls. This study validated the feasibility of generating
intravascular 3.0 T MRI of deep-seated arterial walls in large animals, which should facilitate the translation of this technique
from 1.5 to 3.0 T MR scanner. 相似文献
103.
Z. Shi X. P. Qiu J. T. Zhu R. W. Chantrell S. Mangin S. M. Zhou 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(2):173-176
For FeCr/IrMn bilayers, the exchange bias training effect and the magnetization reversal mechanism are correlated to each other and depend on the composition of the ferromagnetic layer. For high Fe contents, the asymmetric magnetization reversal is observed. During the training effect, both exchange field and coercivity decrease monotonically, suggesting a type I training effect. For low Fe contents, the domain wall depinning takes place for the two hysteresis loop branches. Only exchange field diminution happens in the training effect. The coercivity almost does not change in the process, corresponding to a type II training effect. It is suggested that the motion of antiferromagnetic spins is modified by the magnetization reversal mechanism in the ferromagnetic layer. 相似文献
104.
The solute-solvent interactions of hydrogen-bonded phenol-(H2O)n (n=3-5) clusters in electronic excited states were investigated by means of the time-dependent density functional theory (TDDFT) method. The geometric structures and IR spectra in ground state, S1 state, and T1 state of the clusters, were calculated using the density functional theory (DFT) and TDDFT methods. Only the ring form isomer, the most stable one of the cluster, was considered in this study. Four, five and six intermolecular hydrogen bonds were formed in phenol-(H2O)3, phenol-(H2O)4, and phenol-(H2O)5 clusters, respectively. Based on the analysis of IR spectra, it is revealed that the “window region” between unshifted and shifted absorption bands in both S1 and T1 state becomes broader compared with that in ground state for the corresponding clusters. Furthermore, two interesting phenomenon were observed: (1) with the anticlockwise order of the ring formed by the intermolecular hydrogen bonds in the H-bonded phenol-(H2O)n (n=3-5) clusters, the strengths of the intermolecular hydrogen bonds decrease in all the S0, S1 and T1 states; (2) upon electronic excitation, the smaller the distance between phenol and water is, the larger the change of intermolecular hydrogen bonds strength is. Moreover, the intermolecular hydrogen bond (phenolic OH is the H donor) is strengthened in excited state compared with that in ground state. But the intermolecular hydrogen bond (phenolic OH is the H acceptor) is weakened in excited state. 相似文献
105.
Based on the phenomenological Landau-Devonshire theory, we investigate the film thickness dependence of ferroelectric and electro-optic properties of epitaxial BaTiO3 thin films grown on SrTiO3 and MgO substrates. By using the effective substrate lattice parameter concept, the film thickness dependence of misfit strain is incorporated into the theory. Therefore, the film thickness dependence of ferroelectric and electro-optic properties in epitaxial BaTiO3 thin films can be explained. Moreover, a large quadratic electro-optic effect was obtained in the BaTiO3 thin films, which is in good agreement with the experimental result of BaTiO3 thin films on the MgO substrate. 相似文献
106.
通过透射光谱、x射线激发发射光谱(XSL)的测试,研究了Bridgman法生长的几种不同+3价离子掺杂钨酸铅晶体的发光性能,并利用正电子湮没寿命谱(PAT)和x光电子能谱(XPS)的实验手段,对不同钨酸铅晶体的微观缺陷进行研究.实验表明,不同的+3价离子掺杂,对钨酸铅晶体发光性能的改善不同,并使得晶体中正电子俘获中心和低价氧的浓度发生不同变化.其中掺镧晶体的正电子俘获中心和低价氧浓度均上升,而掺钇和掺铋晶体的正电子俘获中心和低价氧浓度均下降,掺锑晶体则出现了正电子俘获中心浓度上升、低价氧浓度下降的情况.提
关键词:
钨酸铅晶体
+3价离子掺杂
正电子湮没寿命谱
x光电子能谱 相似文献
107.
在C60分子中,未被填充的最低电子态具有T1u对称性,因此,对中性的C60而言,不论是通过分子内部激发,或是外部掺杂,都易被一个电子占据而形成Jahn-Teller(JT)活跃电子态.此态与五重简并的hg声子态耦合,构成所谓的T1u-hg -JT系统.在这一JT系统中,当只考虑电声的线性耦合时,其绝热势能面是一个槽形.但在实际的系统中,二阶电声耦合是存在的,理论研究表明,原来的势槽将被这二阶非线性耦合弯曲成D3d或D5d对称性的势阱.声子振动态在阱中将显示各向异性效应,使得声子沿不同的方向有不同的振动频率,进而影响势阱中的能级分布、势阱间的重叠积分,以及整个系统的隧道能级分裂等.对D3d势阱中各向异性效应进行了研究,利用幺正平移、?pik Pryce和标度变换等方法计算了系统势阱中的能级,以及阱中的振动频率,研究了势阱中的能级间隔以及微绕修正能量的变化,并由此导出了这些物理量在仅有线性耦合的势槽中变化的情形.
关键词:
C60
Jahn-Teller效应
各向异性
电声耦合 相似文献
108.
109.
The enhancement of teleportation fidelity by weak measurement or quantum measurement reversal is investigated. One qubit of a maximally entangled state undergoes the amplitude damping, and the subsequent application of weak measurement or quantum measurement reversal could improve the teleportation fidelity beyond the classical region. The improvement could not be attributed to the increasing of entanglement, quantum discord, classical correlation or total correlation. We declare that it should be owed to the probabilistic nature of the method. 相似文献
110.