Tadpole deposition behaviour in male stream frogs Mannophryne trinitatis (Anura: Dendrobatidae)

Male Mannophryne trinitatis transport their larvae on their backs to predator‐free pools and deposit them there. The experiments reported here investigated M. trinitatis male deposition behaviour in containers placed near a heavily fish‐populated stream at Mount Saint Benedict, northern Trinidad. Choice of deposition site was not related to height above or distance from the stream. The low mean number of tadpoles deposited in each container in the field and in a laboratory experiment indicated that most males tended not to deposit complete clutches in single pools. Deposition experiments in the laboratory with a choice of different‐sized containers showed that deposition was pool size dependent, with more tadpoles deposited in larger containers. Deposition behaviour when given a choice of containers with leaf litter (a source of food and shelter) and with no leaf litter showed no significant preference. Tadpoles grown in different water volumes with different food sources revealed that tadpole growth was best in larger water volumes containing leaf litter. Regular tadpole inspections at a pool in the field established that most tadpoles present were the result of downstream movement.     

Investigation on the synthesis mechanism of β-FeSi2 prepared by pulsed laser deposition

The FeSi2 target alloy was fabricated by conventional powder metallurgy technology, and then, β-FeSi2 thin films was successfully prepared by pulsed laser deposition (PLD). X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the structure, composition, and their changes in the process of β-FeSi2 preparation. In addition, a laser sintering process was also employed to prepare FeSi2 alloy. The analysis of radiation heat transfers in different-sized FeSi2 melt indicates that the cooling rate of the melt depends on the size, i.e., the cooling rate of the micron sized melt is 103 times greater than that of the millimeter-sized melt. The product α-FeSi2 by laser sintering and β-FeSi2 by PLD reveals the different phase transition process in crystallization of milli-meter-sized and micron-sized (or submicron-sized) FeSi2 melt. The results of PLD preparation process shows that β-FeSi2 could be pre-pared through a liquid-phase sintering, followed by a rapid cooling.     

聚-氯对二甲基苯膜的制备与光学特性

以一氯对二甲基苯二聚体为原料，通过真空化学气相沉积法制备聚-氯对二甲基苯（Parylene C）膜，对该高分子膜材料的光学性能进行了研究。     

Magnetoresistance of the thin film ferromagnetic nanoconstrictions

The magnetoresistance and I-V characteristics at different temperatures of the thin film ferromagnetic nanoconstrictions of variable width (from 20 to 250 nm) and 10 nm thicknesses, fabricated by electron beam lithography and vacuum thin film deposition are compared. The magnetoresistance and resistance of the thin film ferromagnetic nanoconstrictions are not related to the width of the nanoconstrictions. Instead the resistance of the local nano-region in the middle of the thin film ferromagnetic nanoconstriction has only a minor role compared to that of the two microscale thin film ferromagnetic electrodes, which contribute the majority of the measured resistance. The magnetoresistances of the thin film ferromagnetic nanoconstrictions and a 0.2 cm × 0.8 cm thin ferromagnetic film deposited under the same conditions were also compared; the thin film ferromagnetic nanoconstrictions have higher magnetoresistances than the thin ferromagnetic film, which implies that the measured magnetoresistance of the thin film ferromagnetic nanoconstrictions comes mainly from the local nano-region in their centers. In conclusion, the measured magnetoresistance of the whole sample is similar to the anisotropic magnetoresistance, because the resistance of the two microscale thin film ferromagnetic electrodes is much higher than that of the local nano-region in the middle of the samples. Comparing the experimental results for the thin film ferromagnetic nanoconstrictions and the thin ferromagnetic film reveals that the magnetoresistance of the local nano-region in the middle of the sample is much higher than that of the two microscale thin film ferromagnetic electrodes attached to it.     

雾化沉积Cu-13．5％Sn合金的显微组织和力学性能研究

本文采用雾化沉积工艺制备了Cu-13．5wt％Sn合金；研究其轧制性能；分析其轧制机理。结果表明：与传统铸造Cu—Sn合金相比，该合金晶粒细小，组织均匀，无宏观偏析，基体为单相α—Cu组织；Sn含量从8wt．％上升到13．5wt．％；轧制后表现出良好的综合力学性能，强度和塑性随着形变量的不同在一个较宽的范围内变化，可以满足不同使用需求；具有高强度（〉800MPa）低弹性模量（～88GPa）的特点。这在晶体金属材料领域是独一无二的，可以预测该合金将会在弹性元件领域具有广泛的应用前景。     

氧离子束辅助激光淀积生长ZnO/Si的XPS研究

利用X射线光电子能谱深度剖析方法对ZnO/Si异质结构进行了分析，用该法可生长出正化学比的ZnO，不过生长的ZnO薄膜存在孔隙，工艺还有待进一步改进。     

油藏原油中石蜡沉淀的模型化研究

考核了正规溶液理论、聚合物溶液理论和状态方程法计算石蜡沉淀的热力学模型 ,并进行了实例计算。计算结果表明 ,对于高压下的油藏流体及油罐油 ,采用状态方程法较适合。在所选用的 4个状态方程中 ,PT和DG状态方程计算精度较高 ,PT方程的稳定性最佳。     

低温下超薄膜分形生长的Monte-Carlo模拟

用 Monte-Carlo方法模拟了不同沉积速率下超薄膜中多粒子扩散、多中心生长的动力学过程。成核率随沉积速率的增大呈指数上升 ,成核率随时间的增大而迅速下降 ;对于确定的沉积速率 ,各个粒子在衬底上的扩散步数相差非常大 ;粒子按扩散步数的分步具有多重分形的特性。     

Pt/Co_3O_4纳米复合材料的合成及其电催化性质

在乙二醇体系中,制备出了具有两种孔径结构的Co3O4空心球,然后以Co3O4空心球作为载体,以葡萄糖作为还原剂,还原H2PtC l6.6H2O可以将Pt颗粒沉积在空心球表面。利用X射线粉末衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM)和能谱分析(EDS)等手段对产物进行了表征。在常温条件下,用CV曲线(Cyclic voltam-m etry)在H2SO4/CH3OH溶液中测试Pt/Co3O4的电化学性质。结果显示:Pt/Co3O4修饰电极能提高Pt的利用率因而具有增强甲醇氧化作用的效果。