Observations of water-flea Daphnia magna and avian fecalia in rock pools: is traditional natural history reporting still relevant for science?

Unexpected observation of freshwater invertebrate Daphnia magna in temporary rock pools on a small island off the Norwegian Atlantic coast confirms colonising ability, mediated through avian dispersal. Robust diapausal eggs of D. magna pass the gut of migrating geese and subsequently hatch in environments where such waterfowl forage and rest along migrating routes. The incubation experiment demonstrates that decomposing fecalia of geese constitute sufficient feed to support developing populations of D. magna in experimental oligotrophic conditions. The findings also show that D. magna is highly adapted for colonisation of temporary pools north of the Arctic Polar Circle, with excellent tolerance to low temperatures. Discussion part I relates the findings to published evidence on avian transport of invertebrate propagules, such as correlations between migration patterns of waterfowl and geographical patterns of aquatic invertebrate diversity. Discussion part II reflects on academic cultures, epistemological aspects of natural history reporting, the presence of a whale cadaver as an ecological indicator and the relevance of simple observation as a starting point for further discourse.     

石墨烯在锂离子电池材料中大有可为

锂离子电池是一种典型的可充电电池,在储能技术领域占主导地位,应用极为广泛。近年来,科技发展对锂离子电池提出了更高要求,包括高能量密度、高安全稳定性等,驱动着电池材料与结构不断创新发展。研制石墨烯基复合正极负极材料,是极为活跃的方向。在此,对锂离子电池的结构、面临的突出挑战以及石墨烯基正极和负极材料研究前沿进行了介绍,重点围绕石墨烯增强电极材料电学特性的基本原理和复合材料制备技术作了阐述,也提出了未来发展动向。     

耗散介观电子谐振腔的量子kirchhoff方程与量子能谱

基于电荷离散化的事实,实现对耗散介观电子谐振腔的量子化.运用Heisenberg运动方程给出体系的量子kirchhoff方程;通过求解体系Hamilton算符的本征值方程分析和研究体系的量子能谱性质.结果表明,量子回路方程、量子能谱均与电荷的量子性质有关.     

对气体输运分子数的讨论

说明担任气体输运任务的分子数是1/6nv和1/4nv的理论依据,并指出这两种分子数担任输运量得到的宏观规律相同的原因。     

Huntington’s disease: from huntingtin function and dysfunction to therapeutic strategies

Huntington’s disease (HD) is a neurodegenerative disorder that usually starts in middle age and is characterized by involuntary movements (chorea), personality changes and dementia, leading to death within 10–20 years. The defective gene in HD contains a trinucleotide CAG repeat expansion within its coding region that expresses a polyglutamine repeat in the protein huntingtin. Together with the characteristic formation of aggregates in HD, aberrant protein interactions and several post-translational modifications affect huntingtin during disease progression and lead to the dysfunction and death of selective neurons in the brains of patients. The exact molecular mechanisms by which mutant huntingtin induces cell death are not completely understood but may involve the gain of new toxic functions and the loss of the beneficial properties of huntingtin. This review focuses on the cellular functions in which huntingtin is involved and how a better understanding of pathogenic pathways can lead to new therapeutic approaches. Received 24 May 2006; received after revision 5 July 2006; accepted 23 August 2006     

弹性需求用户平衡分配模型及其应用

对具有弹性需求的交通网络随机用户平衡分配问题进行了分析研究,将其描述为一个等价的变分不等式。最后将模型应用于拥护公交网络系统的平衡分配问题,并针对公交网络系统的特殊性,提出相应的求解算法 法。实例表明了模型的合理性和算法的有效性。     

利用扫描电镜分析砍创性骨外伤的研究

在大型显微镜下,对锐器（单刃刀）和钝器（短柄斧）形成的骨外伤的微观形态进行了分析研究．结果表明：通过特征识别骨外伤的砍切痕迹,往往误差较大,某些肉眼看不见的三维特征通过微观分析可以清晰地识别．着重强调扫描电镜（SEM）在骨外伤鉴定中,具有重要的使用价值．     

发展武警部队集装化运输保障探讨

武警部队后勤物资运输保障多采用散装的形式,保障效率低。通过分析外军与解放军后勤物资集装化运输现状,结合执行多样化任务的实际,阐述武警部队后勤物资集装化运输的意义,最后提出发展集装化运输的构想。     

超纯铁素体不锈钢热变形过程中的析出行为

利用热力模拟实验机及试验轧机研究了添加Ti,V的超纯中铬铁素体不锈钢热变形过程中的析出行为变化特点,并采用热动力学计算及透射电子显微镜观察来表征析出相特征.结果表明:热变形过程中形成的析出相主要为TiC,这与热动力学分析一致.这些析出相的特征与变形温度密切相关,随着变形温度的降低,析出相TiC尺寸更加细小且分布更加弥散.这主要是由于变形温度降低时扩散速率相对较低,不利于析出相长大,而晶体缺陷增加,形变诱导析出的有效形核位置增加.这一热变形过程中的析出行为变化规律在中试试验条件下得到了验证.     

电子贴附解离过程中的物理和化学

电子贴附解离是低能量电子与分子碰撞的重要过程,涉及电子与靶分子的相互作用、电子-分子共振态、瞬态负离子分子的解离动力学等基础物理和化学问题.本文对近年来该领域的重要进展,特别是基于负离子速度成像方法的实验研究,进行了阶段性总结,并对其未来发展方向和潜在应用进行了讨论.