岩溶石漠化山地不同退耕模式土壤抗蚀性及其与结构体分形关系研究

通过对岩溶石漠化山地中小尺度范围内的现有三种主要退耕模式及对照地土壤抗蚀性主成分分析及与各级结构体分形维数关系研究，结果表明：（1）研究区退耕地在3～6年内土壤抗蚀性均发生了比较明显的变化，但都介于传统耕地与马尾松次生灌丛之间，其中以具有复式结构的退耕樟树＋草被退耕模式的抗蚀效果较理想；（2）与传统旱耕地不同，各退耕模式土壤抗蚀性均是A层土壤强于B层土壤，表明退耕有利于A层土壤抗蚀性迅速提高，尤其是草本＋乔灌模式对A层土壤抗蚀性的提高更为显著；（3）〉O．25mm水稳性团聚体含量及破坏率、水稳性指数、有机质含量为评价土壤抗蚀性的最佳四指标；（4）微团聚体、风干团聚体分形维数表征土壤抗蚀性有一定的局限性，而机械组成、水稳定性团聚体分维数与抗蚀性综合分值相关性较高，尤其是水稳性团聚体分形维数可较好地反映出土壤的抗蚀特性。

用改进的分形结构法测量牛奶酪蛋白分子尺寸

分形结构法是一种测量蛋白质分子尺寸的新方法,但该方法在实际实践中有许多的不足,如:实验周期过长、计算方法太过复杂、对实验条件和设备要求过高等等;针对这些情况,对分型结构法进行了一些改进,如:简化计算方法、在保证精度的同时简化实验过程、缩短实验周期等等;实验结果表明:改进方法后的实验结果和原来高精度实验方法结果相近,误差较小,达到了预期的目的;这证明改进后的方法能够测量牛奶蛋白质分子尺寸。

Morphology effect of zirconia support on the catalytic performance of supported Ni catalysts for dry reforming of methane

An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.

Yarn Architecture Analysis of Two-step 3D Braided Composites

A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yarns and the intertwining between braider yams and axial yams are analyzed from experimentation. With the microstructure being defined, three levels of unit cell structure are identified, i.e. large unit cell, second unit cell and minimal unit cell. Secondly, based on the minimal unit cell in the interior and on the boundary of the entire cross-section, the deformations of axial yams squashed by braider yams contribute to the increase of the fiber packing factors of axial yams. Finally, the predicted fiber volume fraction of the composites decreases with the increase of linear density of the braider yam and the pitch length. Favorable correlations between the predicted and the experimental results arc found for six groups of the composites.

北川震裂带柳杉林地土壤功能特性试验分析

汶川地震形成了大面积的震裂带,震裂带内水土流失严重。本文重点从土壤结构体分形维数、有机质含量、土壤抗冲性三个方面探讨了北川震裂带柳杉林地土壤结构功能特性,分析了地震裂隙程度对土壤结构体分形维数、有机质含量、土壤抗冲性的影响及其与土壤深度的相关性。结果表明地震裂隙程度对土壤结构体分形维数影响不显著,而地震3 a后强度裂隙样地土壤有机质含量、抗冲性大于中度裂隙或弱度裂隙样地;各样地土壤有机质含量、抗冲性与土壤深度显著负相关,有机质含量与土壤抗冲性存在显著的正相关关系。