Structural and magnetic properties of pulsed laser deposited SrRuO3/CoFe2O4/La2/3Sr1/3MnO3 magnetic oxide heterostructures on SrTiO3(001) and MgO(001)

We report on the growth of all-oxide SrRuO₃/CoFe₂O₄/La_2/3Sr_1/3MnO₃ and La_2/3Sr_1/3MnO₃/CoFe₂O₄/SrRuO₃ heterostuctures on SrTiO₃(001) and MgO(001) substrates by pulsed laser deposition. Structural analyses by X-ray diffraction and transmission electron microscopy clearly indicate the preservation of epitaxial relations when the La_2/3Sr_1/3MnO₃ layer is grown first, whereas trilayers with SrRuO₃ at the bottom are more disordered. Both the substrate material and the deposition sequence strongly influence the formation of various structural defects such as interfacial dislocations and sub-grain structures, and this is clearly reflected by a reduction of the saturation magnetization in the top electrode. When the substrate material and the deposition sequence are correctly chosen, however, the magnetic moments of the La_2/3Sr_1/3MnO₃ and SrRuO₃ layers reverse independently, and the La_2/3Sr_1/3MnO₃ layer retains bulk-like magnetic properties.     

Optical bistability based on surface plasmon coupled between two noble metal films involving Kerr materials

We successfully investigate an optical bistability phenomenon in a layered structure consisting of Kretschmann configuration involving the Kerr-type nonlinear and the silver film. Pure theoretical approaches are employed to investigate that the surface plasmon could easily be coupled and both the reflection and transmission curves versus the incident intensity forms optical bistability. The transmission curves are greatly influenced by the thickness of the second silver film. These results may be useful for designing novel surface plasmon-based optical devices and will be essential for future classical and quantum information processes.     

A study on the interior microstructures of working Sn particle electrode of Li-ion batteries by in situ X-ray transmission microscopy

The interior microstructures of Sn particles developed during electrochemical lithiation/de-lithiation have been revealed by in situ X-ray transmission microscopy (TXM). The Li-alloying particles exhibited the formation of core–shell internal structure along with crack formation within the lithiated zone during the first lithiation. The extent and speed of the expansion process was shown to be a strong function of particle size. Upon completion of the first de-lithiaiton, the particles only partially (～10%) contracted, while re-crystallization of Sn continued to take place within the interior of the particles during a following idle period. The re-crystallization process alleviated the pulverization problem and led to the formation of porous Sn particles, which exhibited remarkably attenuated dimensional variations during subsequent cycles.     

Synthesis and fungicidal activity of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines

A number of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines were synthesized.The structures of these new compounds were confirmed by ~1H NMR,IR and elemental analysis.Biological evaluation in the greenhouse showed several compounds have good fungicidal activities at 25 mg/L.     

A volume-amending method to improve mass conservation of level set approach for incompressible two-phase flows

A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three- dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.     

Giant Nonlinear Absorption by an Ensemble of Metallic Grains

We have investigated the nonlinear low-frequency microwave absorption of an ensemble of small metallic grains. Earlier Zhou et al. [Phys. Rev. Lett. 77, 1958 (1996)] have proved that linear absorption by such a system is due to a mesoscopic relaxation mechanism for which important contribution is from the grains with small level spacings between the ground state and the first excited state. Here we have shown further that such grains are anomalously sensitive to the field amplitude and the distribution of level spacings. Since such a behavior depends on external magnetic field, we expect the appearance of a giant nonlinear magnetoresistance, as well as a very strong temperature dependence of the nonlinear microwave conductivity.     

A reapproach to the generation and reaction mechanism of cyclopropylidenes

By the comparison of the reaction products of gem-dihalocyclopropanes under various conditions, it is suggested that similar to the reactions with metals, the reactive radical intermediates which make the reaction results complicated are formed in the reactions of gem-dihalocyclopropanes with alkyl lithium. Studies on the competitions between ring opening and intramolecular C—H insertions of cyclopropylidenes generated by the reactions of gem-dihalocyclopropanes with metals and discussions on the reaction mechanism are also given in this paper.     

Non‐Alkaloidal Constituents from the Stem of Ficus Septica

Seven triterpenes, two lignans, and twelve other known compounds were isolated from the non‐alkaloidal fractions of the stem of Ficus septica Among these triterpenoids, a rare triterpene skeleton derivative, 13,27‐cycloursan‐3β‐ylacetate was isolated from natural sources for the first time. All the structures of these compounds were elucidated by spectroscopic methods.     

正电子放射层析成象系统设计的计算机模拟

在一个简单实用的数学模型基础上,利用现代计算机技术对正电子放射层析成象系统(PET)进行了模拟,并详细讨论了闪烁晶体材料的物理、几何特性以及探测器环直径的大小对于PET系统的空间分辨率的影响.本文所得的结论对于开发和设计PET系统来说,是非常有用的.