Large scale production of carbon nanotube arrays on the sphere surface from liquefied petroleum gas at low cost

Liquefied petroleum gas (LPG), a cheap industrial material, is used as carbon source to produce carbon nanotube (CNT) arrays on ceramic spherical surface on a large scale in the floating catalyst process. The ceramic spheres provide huge surface area and good mobility, leading to the mass production of CNT arrays continuously. The arrays obtained from the surface are of good alignment, and the purity is as high as 97.5%. With the decrease of the growth temperature, CNTs in the array form with small-diameter of about 13 nm can be obtained. Therefore, with the industrial fuel as carbon source and the ceramic sphere as substrate, CNT arrays can easily be produced on large scale at low cost.     

Asymmetric energy flow in coupled nonlinear LC transmission line

We constructed a coupled LC transmission line and studied the propagation of waves in it. We found asymmetric energy flow when we changed the driving conditions at the boundary. We analyzed this change and believe that it occurs because of the bandpass characteristics of the LC transmission line and high-order harmonic waves induced by nonlinearities. The LC transmission line could be used to simulate a microscopic crystal lattice. Therefore, we hope to observe thermal rectification in the system. We investigated the dependence of the system on different parameters, and then discussed the multi-frequency condition to aid in experimental verification.     

不同声压下酒精水溶液中的单泡声致发光

测量了不同浓度酒精水溶液中单泡声致发光随驱动超声声压大小变化关系曲线. 结果表明, 根据光强-声压(I-P_a)曲线的变化关系, 可以把酒精浓度分为3个区域. (1) 在较低浓度时, 随着酒精浓度的增加, 曲线往低声压方向移动, 驱动声压变化较大; 相同声压下, 单泡声致发光的发光强度随酒精浓度增加而增加. (2) 当酒精浓度稍高时, 驱动声压变化较小; 相同声压下, 单泡声致发光光强随酒精浓度的增加而降低. (3) 进一步增加酒精浓度, 光强随酒精浓度变化关系趋势在不同声压下的关系不同, 但I-P_a曲线的斜率随酒精浓度的增加而降低. 可以通过气泡动力学以及酒精的物理化学性质解释这些结果, 同时这些结果也有助于进一步了解单泡声致发光的发光机制.     

A phenomenological model of mass-exchange between the inside and outside of a cavitation bubble

The mass-exchange between the inside and outside of a cavitation bubble is a complicated process with several kinds of exchange forms acting together, such as gas diffusion, gas-liquid phase transition, chemical reactions and so on. A phenomenological model of mass-exchange was proposed, in which the pressure difference is considered as the drive. Compared with the previous physical models, it has a simpler form and less computational cost. Combining it with Rayleigh-Plesset equation, the equilibrium radius is calculated when the mass-exchange achieves the dynamic balance. The result shows that the equilibrium radius has multiple values. The relationships between the equilibrium radius and the driving ultrasound (pressure amplitude and frequency) are evaluated. We also investigated how these relationships were affected by the model parameters. Finally, the bubble radius evolution in the sulfuric acid driven by different pressures was measured. The experimental result that the equilibrium radius changes with the pressure agrees with the numerical results well. Supported by the National Natural Science Foundation of China (Grant Nos. 10434070, 10704037), the Key Project of Chinese Ministry of Education (Grant No. 103078) and the Young Scholar Technological Innovation Projects of Jiangsu Province (Grant No. BK2007569)     

二阶微分方程的可积性判据

研究二阶微分方程的可积性,通过引进起中介传媒作用的函数f（x）,φ（x）等,经函数变换,有效地将二阶线性微分方程降至一阶求解．文中还找到该类方程可积的若干个充分判据,给出用中介函数f（x）,φ（x）等表示的二阶微分方程通解的积分表达式．     

Asymmetric energy flow in coupled nonlinear LC transmission line

We constructed a coupled LC transmission line and studied the propagation of waves in it. We found asymmetric energy flow when we changed the driving conditions at the boundary. We analyzed this change and believe that it occurs because of the bandpass characteristics of the LC transmission line and high-order harmonic waves induced by nonlinearities. The LC transmission line could be used to simulate a microscopic crystal lattice. Therefore, we hope to observe thermal rectification in the system. We investigated the dependence of the system on different parameters, and then discussed the multi-frequency condition to aid in experimental verification.     

Cylindrical PCL brushes on the surface of lanthanum hydroxide nanowires by ring-opening polymerization

A core-shell hybrid nanostructure,a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of brushes of poly (ε-caprolactone) (PCL), has been successfully prepared by ring-opening polymerization (ROP) on the surface of nanowires. Such special structures were proved by TEM images. Meanwhile, the thickness of polymer layers was measured. The chemical component and the grafted PCL quantity of the sample were characterized by FTIR and TGA, which provides a simple and universal method to...     

Transfer of a eubacteria-type cell division site-determining factor CrldfnD 8ene to the nucleus from the chloroplast genome in Chlamydomonas reinhardtii

MinD is a ubiquitous ATPase that plays a crucial role in selection of the division site in eubacteria, chloroplasts, and probably Archaea. In four green algae, MesosUgma viride, Nephroselmis olivacea, Chlorella vulgaris and Prototheca wickerhamii, MinD homologues are encoded in the plastid genome. However, in Arabidopsis, MinD is a nucleus-encoded, chloroplast-targeted protein involved in chloroplast division, which suggests that MinD has been transferred to the nucleus in higher land plants. Yet the lateral gene transfer （LGT） of MinD from plastid to nucleus during plastid evolution remains poorly understood. Here, we identified a nucleus-encoded MinD homologue from unicellular green alga Chlamydomonas reinhardtii, a basal species in the green plant lineage. Overexpression of CrMinD in wild type E. coil inhibited cell division and resulted in the filamentous cell formation, clearly demonstrated the conservation of the MinD protein during the evolution of photosynthetic eukaryotes. The transient expression of CrMinD-egfp confirmed the role of CrMinD protein in the regulation of plastid division. Searching all the published plastid genomic sequences of land plants, no MinD homologues were found, which suggests that the transfer of MinD from plastid to nucleus might have occurred before the evolution of land plants.