Crystallization behavior of blends of high-density polyethylene with novel linear low-density polyethylene

Blends of high-density polyethylene (HDPE) with novel linear low-density polyethylene (LLDPE) samples in the whole range of compositions were investigated by means of differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). The LLDPEs are ethylene/octene-1 copolymers prepared with a single-site catalyst, with a narrower distribution of branches compared to Ziegler-Natta type polymers. It was found that cocrystallization or separate crystallization in the blends profoundly depends on the content of branches in the LLDPE, while the critical branch content of the novel LLDPE for separate crystallization is much lower than that of commercial LLDPE (prepared with Ziegler-Natta catalysts). This implies that the miscibility of linear and branched polyethylene is also affected by the distribution of branches. The marked expansion of the unit cell in cocrystals, which are formed by HDPE with the novel LLDPE, indicates that the branches are included in the crystal lattice during the cocrystallization process. The result is very helpful to understand the phenomenon that the unit cell dimensions of commercial branched polyethylene are larger than those of linear polyethylene.

定量分析丙烯酰胺水溶液中微量有机杂质

本文采用XE-60毛细管单柱色谱法,快速、准确测定了丙烯酰胺水溶液中的有机杂质,定量测定结果的重现性良好.

台湾东北部及吕宋海峡黑潮的水文动力学分析

本论文应用一种流函数投影方法对台湾东北部黑潮近二十年的历史水文数据进行了诊断分析。 结果表明，苏澳海脊北部位于冲绳海槽西南角的黑潮中层水的盐度明显高于周围海区；而位于1000m以下的冲绳海槽黑潮深层水相对于苏澳海脊以南的黑潮深层水具有高温低盐的特征，反映了苏澳海脊对黑潮水团的阻挡作用；位于300m 以浅的冲绳海槽黑潮热带水相对于苏澳海脊以南的黑潮热带水具有低温低盐的特征。针对冲绳海槽西南角黑潮中层水高盐中心的成因，分析表明除了苏澳海脊的阻挡作用外，台湾东北部的气旋式冷涡与黑潮主体在陆架坡折交汇区的垂直混合过程是需要考虑的关键因素。另外，针对吕宋海峡黑潮表层水入侵南海的现象，本文结合卫星高度计数据对Argos漂流浮标轨迹进行了初步分析，结果显示除了风生Ekman流之外黑潮地转流也起着重要的平流作用。

Two new species of Leymus (Poaceae : Triticeae) from Qinghai, China

Two new species of Leymus, L. pendulus and L. obvipodus, are described and illustrated. These two species are endemic to Qinghai province, China, occurring at the margins of woodlands, wastelands, mountain valleys, and the bases of walls, at 2280-2400 m elevation. Leymus pendulus is unusual in its lax, long, pendent spikes. It is closely related to L. flexus, but differs from that species by pendent spikes, longer rachis internodes, and shorter glumes and lemmas. Leymus obvipodus is unique in the genus in having all spikelets pedicellate. It resembles both L. divaricatus (Drobow) Tzvelev and L. aristiglumus L. B. Cai but differs from the former by lanceolate glumes with 1 to 3 nerves, longer spike-like panicles, taller culms, and lanceolate lemmas with 5 obscure nerves and pubescent margins, and from the latter by lax, longer spike-like panicles, pedicellate spikelets with 4 to 8 florets, narrower glumes, and longer, lustrous lemmas.

青藏高原东部电性结构特征及其构造意义

Eastern Himalayan Syntaxis (EHS) and its surroundings (eastern margin of Tibet) is one of the most complicated tectonic areas in the world. As the exhaust opening of the balanced materials of the Tibetan Plateau during the collision of Indan and Eurasian plates, the deep structure beneath EHS surrounding region is referred to as the key to the study of the dynamics of the plateau. EHS3D project, sponsored by NSFC, has been proposed to explore the deep electric features of the area. During the first stage of EHS3D(2006-2008), MT+LMT measurements have been conducted along two lines from Chayu to Qingshuihe (EHS3D-3) and Chayu to Ruoergai (EHS3D-2). This paper will discuss the MT models of EHS3D-3 line. By the data procrssing, including distortion analysis, Robust estimation and strike decomposition, rotated apparent resitivities and phases have been obtained for each station. Then conventional 2-D inversion algorithms (NLCG and RRI) were employed to produce 2-D models. The final preferred 2-D model suggests that the upper crust consists of resistive blocks while in mid-lower crust there are two extensive conductive bodies beneath Lhasa block and Qiangtang terrain respectively. Jinshajiang suture is a gradient belt and Bangong-Nujiang suture appear a conductive belt dipping to the north. . We concluded that the formation of the two conductive bodies attributed to the partial melt and fluids in the lower crust. The regional electric strike derived from decomposition analysis indicates that the crust and upper mantle move in different manners. The upper crust moves like slips of rigid blocks along major slip faults while the lower crust creeps as a flow in the conductive channels.