Production of new superheavy Z=108-114 nuclei with U-238, Pu-244, and Cm-248,Cm-250 targets

Within the framework of the dinuclear system (DNS) model, production cross sections of new superheavy nuclei with charged numbers Z=108-114 are analyzed systematically. Possible combinations based on the actinide nuclides U-238, Pu-244, and Cm-248,Cm-250 with the optimal excitation energies and evaporation channels are pointed out to synthesize new isotopes that lie between the nuclides produced in the cold fusion reactions and the Ca-48-induced fusion reactions experimentally, which are feasible to be constructed experimentally. It is found that the production cross sections of superheavy nuclei decrease drastically with the charged numbers of compound nuclei. Larger mass asymmetries of the entrance channels enhance the cross sections in 2n-5n channels.

PU软段结构对PU／PMMA IPN中两组分相容性的影响

用同步法合成了４种聚氨酯／聚甲基两烯酸甲酯互穿聚合物网络（ＰＵ／ＰＭＭＡＩＰＮ），利用ＤＤＣ、ＴＥＭ和动态力学谱（ＤＭＳ）等手段综合研究了ＩＰＮ中两组分的相容性和相态结构，用基团贡献加和方法计算了各种ＰＵ和ＰＭＭＡ的溶度参数δ，结合ＰＵ软段链结构讨论了各种ＩＰＮ呈现不同相容性和相态结构的原因。

Two bifurcation transitions of the floating half zone convection in a fat liquid bridge of larger Pr

The transient process of the thermocapillary convection was obtained for the large Pu floating half zone by using the method of three-dimensional and unsteady numerical simulation. The convection transits directly from steady and axisymmetric state to oscillatory flow for slender liquid bridge, and transits first from steady and axisymmetric convection to the steady and non-axisymmetric convection, then, secondly to the oscillatory convection for the fatter liquid bridge. This result implies that the volume of liquid bridge is not only a sensitive critical parameter for the onset of oscillation, but also relates to the new mechanism for the onset of instability in the floating half zone convection even in case of large Prandtl number fluid.

Oscillatory Flow Induced Hydrodynamic Forces upon a Pipeline near Erosive Sandy Seabed

An experimental study of the properties of hydrodynamic forces upon a marine pipeline is presented in this paper, in the equilibrium scour conditions for various Keulegan-Carpenter numbers and various initial relative gaps between pipeline and the erosive sandy seabed. The tests are conducted in a U-shaped oscillatory water tunnel with a sand box located at the bottom of the test section. According to the experimental results, the maximum horizontal forces on the pipelines with an initial gap to seabed will decrease to some extent due to scouring process. For engineering appliances, it seems safer to estimate wave induced forces on pipelines under the assumption that seabed is plane. However, it should be noticed that great changes would be brought to the frequency properties of lift forces because of the sandy scour beneath the pipeline, which occurs for certain KC numbers.

Numerical simulation of condensation of bubbles under microgravity conditions by moving mesh method in the double-staggered grid

A numerical 2D method for simulation of two-phase flows including phase change under microgravity conditions is presented in this paper, with a level set method being coupled with the moving mesh method in the double-staggered grid systems. When the grid lines bend very much in a curvilinear grid, great errors may be generated by using the collocated grid or the staggered grid. So the double-staggered grid was adopted in this paper. The level set method is used to track the liquid-vapor interface. The numerical analysis is fulfilled by solving the Navier-Stokes equations using the SIMPLER method, and the surface tension force is modeled by a continuum surface force approximation. A comparison of the numerical results obtained with different numerical strategies shows that the double-staggered grid moving-mesh method presented in this paper is more accurate than that used previously in the collocated grid system. Based on the method presented in this paper, the condensation of a single bubble in the cold water under different level of gravity is simulated. The results show that the condensation process under the normal gravity condition is different from the condensation process under microgravity conditions. The whole condensation time is much longer under the normal gravity than under the microgravity conditions.

A Wide Band Strong Acoustic Absorption in a Locally Network Anechoic Coating

Composite materials with interpenetrating network structures usually exhibit unexpected merit due to the cooperative interaction. Locally resonant phononic crystals (LRPC) exhibit excellent sound attenuation performance based on a periodical arrangement of sound wave scatters. Inspired by the interpenetrating network structure and the LRPC concept, we develop a locally network anechoic coating (LNAC) that can achieve a wide band of underwater strong acoustic absorption. The experimental results show that the LNAC possesses an excellent underwater acoustic absorbing capacity in a wide frequency range. Moreover, in order to investigate the impact of the interpenetrating network structure, we fabricate a faultage structure sample and the network is disconnected by hard polyurethane (PU). The experimental comparison between the LNAC and the faultage structure sample shows that the interpenetrating network structure of the LNAC plays an important role in achieving a wide band strong acoustic absorption.

Optical bistability via amplitude and phase control of a microwave field

We investigate the steady-state optical bistability behavior in a three-level A-type atomic system closed by a microwave field under the condition that the applied fields are in resonance with corresponding atomic transitions. It is shown that the bistable hysteresis cycles can be controlled by both the amplitude and the phase of the microwave field. (c) 2006 Elsevier B.V. All rights reserved.

青藏高原几种植物的光合特性研究

通过气体交换、荧光猝灭动力学以及反射光谱等技术研究了两个青稞（Hordeum vulgare L.）品种的光合特性及激发能分配。结果表明，青稞的光饱和点1000 μmol m-2 s-1左右。在0～500 μmol m-2 s-1的光强范围里，青稞叶片的光呼吸(Pr)随着光强升高而增加;光强超过500 μmol m-2 s-1以后，光呼吸变化不明显。光呼吸占总光合的比例(Pr/Pm)随光强增强下降。随着光强增强，PSⅡ有效光化学量子效率（Fv′/Fm′），PSⅡ反应中心的实际光化学量子效率（ΦPSⅡ），光化学猝灭系数（qP）不断降低而青稞叶片的非光化学猝灭(NPQ)不断升高，说明越来越多的光能以热耗散的形式耗散掉。光谱分析表明△PRI 随着青稞叶片暴露于光下的时间迅速增大。因此，我们认为光呼吸不是青稞主要的光破坏防御机制，依赖叶黄素循环的热耗散可能是田间青稞耗散过剩光能的主要途径。 通过气体交换、荧光猝灭动力学等技术研究了四种乔木在拉萨和那曲的光合特性及激发能分配。结果表明，四种乔木藏川杨（Populus szechuanica var. tibetica schneid.），银白杨（Populus alba L.），左旋柳(Salix paraplesia var. subintegra C. Wang et P. Y. Pu)，墨竹柳(Salix maizhokunggarensis N. Chao)在拉萨市的光合速率（Pn），叶片气孔导度（Gs），蒸腾速率（Tr）均显著高于那曲。藏川杨和墨竹柳的光下实际光化学效率（ΦPSⅡ）在拉萨显著高于那曲，银白杨和左旋柳的光下实际光化学效率在拉萨和那曲没有显著差异。四种乔木开放反应中心激发能捕获效率（Fv′/Fm′）和天线热耗散（1－Fv′/Fm′）在拉萨和那曲的差异不显著。测量光合时的气温（Tair）拉萨显著高于那曲，除墨竹柳外叶温（Tleaf）也显著高于那曲，墨竹柳的上述两参数在两地间无显著差异。除藏川杨外其余三种乔木在拉萨的胞间二氧化碳浓度（Ci）显著高于那曲，气孔限制值(Ls)显著低于那曲，藏川杨的上述两指标在两地间无显著差异。除墨竹柳外，其余三种乔木在两地的光合（Pn）与叶温（Tleaf）成显著正相关。对银白杨和左旋柳来说，低叶温通过降低气孔导度（Gs）从而降低胞间二氧化碳浓度（Ci）是造成那曲光合低的主要因素之一。对于墨竹柳来说，可能有其他非温度的环境条件影响其气孔导度进而造成气孔限制。此外，叶温可能主要通过非气孔限制来影响藏川杨的光合速率。因此，我们认为在西藏地区不同乔木对海拔高度的响应机制可能不同，但具体机制还需要进一步研究。

Sequence variation and genetic diversity in the giant panda

About 336-444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene, and unfortunately, might have suffered bottle-neck attacks. Afterwards, its genetic diversity seemed to recover to same extent.