Induced Defensive Response of Myrtle Oak to Foliar Insect Herbivory in Ambient and Elevated Co2

The rising level of atmospheric CO2 has stimulated several recent studies attempting to predict the effects of increased CO2 on ecological communities. However, most of these studies have been conducted in the benign conditions of the laboratory and in the absence of herbivores. In the current study, we utilized large octagonal chambers, which enclosed portions of an intact scrub-oak community to investigate the interactive effects of CO2 and insect herbivory on myrtle oak, Quercus myrtifolia. Specifically, we assessed the effects of ambient and elevated CO2 (2x current concentrations) on percent foliar nitrogen, C:N ratio, total relative foliar tannin content, and the presence of leaf damage caused by leaf mining and leaf chewing insects that feed on myrtle oak. Total foliar N declined and C:N ratios increased significantly in oaks in elevated CO2 chambers. The percentages of leaves damaged by either leafminers or leaf chewers tended to be lower in elevated compared to ambient chambers, but they co-occurred on leaves less than expected, regardless of CO2 treatment. Leaves that had been either mined or chewed exhibited a similar wounding or defensive response; they had an average of 25 and 21% higher protein binding ability, which is correlated with tannin concentration, compared to nondamaged control leaves, respectively. While the protein-binding ability (expressed as total percent tannin) of leaves from elevated CO2 was slightly higher than from leaves grown in ambient chambers, this difference was not significant.     

Metallo-Supramolecular Polymerization: A Route to Easy-To-Process Organic/Inorganic Hybrid Materials

The self-assembly polymerization of ditopic macromolecules via metal–ligand binding is a facile route for the preparation of metallo-supramolecular polymers (MSPs). We herein review our recent work focused on the synthesis and investigation of metallo-supramolecular polymers based on 2,6-bis(1′-methylbenzimidazolyl)pyridine endcapped poly(p-phenylene ethynylene) and poly(p-xylene) macromonomers. These materials are readily solution-processable and display appreciable mechanical properties as well as other attractive properties such as specific opto/electrical functions or high thermal stability. Our work illustrates that metallosupramolecular polymerization offers an attractive approach to assemble high-molecular-weight macromolecules from well-defined, easy to process precursors. Variation of the ditopic ligands and metal ions allows one to easily tailor the desired properties. This paper is dedicated to Professor Ian Manners and his scientific accomplishments.     

天然橡胶/顺丁橡胶并用硫化胶的力学破坏机理

用扫描电子显微镜对天然橡胶／顺丁橡胶并用硫化胶的力学破坏机理进行了研究，结果表明试验样拉伸疲劳破坏断面具有拉伸断裂和屈挠龟裂的双重特征。白炭黑和Ｓｉ６９的加入使硫化胶的屈挠疲劳初始裂口形式发生变化。热氧老化使试样的拉伸断裂由韧性向脆性转化。     

Pulsed Electric Current Sintering of Silicon Nitride

Pulsed electric current sintering (PECS) has been used to densify α-Si₃N₄ powder doped with oxide additives of Y₂O₃ and Al₂O₃. A full density (>99%) was achieved with virtually no transformation to β-phase, resulting in a microstructure with fine equiaxed grains. With further holding at the sintering temperature, the α-to-β phase transformation took place, concurrent with an exaggerated grain growth of a limited number of elongated β-grains in a fine-grained matrix, leading to a distinct bimodal grain size distribution. The average grain size was found to obey a cubic growth law, indicating that the growth is diffusion-controlled. In contrast, the densification by hot pressing was accompanied by a significant degree of the phase transformation, and the subsequent grain growth gave a broad normal size distribution. The apparent activation energy for the phase transformation was as high as 1000 kJ/mol for PECS, almost twice the value for hot pressing (∼500 kJ/mol), thereby causing the retention of α-phase during the densification by PECS.     

From surface science to catalysis: Surface “explosions” observed on Rh crystals and supported catalysts

Phenomena called surface explosions have been reported for decomposition reactions on single crystals, and have been identified by the use of desorption methods. In particular, in TPD, they are manifested by extremely narrow peaks (as little as 3 K in width) and a desorption rate which increases with time in isothermal experiments. In this paper we report such observations for acetate species on Rh single crystals, but extend this to show for the first time that such effects are not restricted to single crystal/UHV experiments, but can also be found on a Rh/Al₂O₃ catalyst under ambient pressure conditions. These reactions can be classified as second order autocatalytic surface processes, where free surface Rh sites are an essential component of the reaction. It is shown that coadsorbed adatoms are also essential for such explosions to be seen and their role is proposed to be that of a template layer acting to order the acetate in self-poisoning configurations.     

D-23.5/131-143氮氢气循环压缩机气阀改造

D-23．5／131-143氮氢气循环压缩机是四川美丰化工股份有限公司德阳分公司新建200kt／a合成氨及300kt／a尿素工程的关键设备之一。该压缩机装机试运行时，电机电流过大，严重影响整个系统的正常运行。通过分析发现，该压缩机气阀通流面积过小，为此，从气阀结构型式、气流通道等方面对该压缩机气阀进行改造。改造后的气阀装机投用后，压缩机电机电流得到较大幅度下降且具有良好的可靠性。     

观测几何对目标探测性能影响的仿真分析

在光电武器作战探测目标性能问题的研究中,不同大气/气溶胶模式、不同观测几何条件下的光电武器作战效能差异显著.针对上述问题,通过分析大气传输和观测几何对视在对比度的影响,建立了视在对比度传递模型,结合TIP准则提出了观测几何对目标探测性能的影响模型.利用Modtran软件离线计算的基础数据,提出了探测性能模型快速仿真计算方法,实现了典型地区、全天时、不同观测几何和观测距离条件下的成像系统探测性能的快速仿真计算.采用快速仿真计算方法,选取典型参数,计算并分析了不同大气/气溶胶模式、观测几何等因素对视在对比度、探测概率和探测距离等指标的影响.结果表明:观测几何对目标探测性能影响显著,50％探测概率条件下,顺光探测距离是逆光探测距离的1.38 ～1.7倍;不同大气/气溶胶模式条件下,观测几何对探测距离影响差异明显,海洋性气溶胶模式下影响较大,乡村型气溶胶模式下影响较小.文中提出了观测几何对目标探测性能的影响模型和快速仿真计算方法,为光电武器系统任务规划和作战效能评估提供了理论和技术支持.     

静态混合器对PP/MMT纳米复合材料微观形态的影响

以聚丙烯／蒙脱土纳米复合材料(PP／MMT)为原料，在单螺杆挤出装置上，通过连接Kenics静态混合器，研究了静态混合器对PP／MMT微观形态的影响，并用透射电子显微镜(TEM)研究了MMT在PP中分散的形态。结果表明：通过Kenics静态混合器混合后，MMT在基体PP中的分散更加均匀，并出现明显的片层剥离；混沌混合是获取剥离型PP／MMT的有效手段。     

丙烯酸乙酯合成反应产物的GC／MS分析

本文叙述了丙烯酸乙酯合成产物的ＧＣ／ＭＳ分析．从分析结果看出，本应在酯化反应前除去的ＣＨ３Ｃｌ３仍有较大的含量，这也许是导致丙烯酸乙酯被氯代的原因。     

多核程序交互理论及应用

多核处理器上共享缓存使用效率,即程序局部性是影响并行程序性能的关键因素之一。提出了以足迹为基础的局部性理论。介绍了缺失率、重用距离和足迹之间的转化关系,并利用足迹可组合性特征建立了并行程序局部性预测模型。