The behaviour of Cotinis nitida Linnaeus,the green June beetle (Coleoptera: Scarabaeidae), on mowed lawns makes them especially vulnerable to bird predators

ABSTRACT

Males of the green June beetle Cotinis nitida are regularly attacked by birds as they search for females on lawns but which bird species feeds on the beetle changes from year to year. In 2018 for the first time on a farm in northern Virginia, brown thrashers (Toxostomum rufum) joined blue jays (Cyanocitta cristata) as major predators of the beetles. The two species employed very different tactics when hunting for June beetles, with the thrashers searching while walking forward on the mowed lawn while the jays scanned for beetles when perched in trees about the lawn. The beetles became very scarce at the lawn in early July in 2017 and 2018 and their predators apparently moved elsewhere. Subsequently, male beetles were occasionally observed patrolling a nearby hayfield in search of mates with rare copulations recorded after July 15. Because predatory birds could not exploit the beetles in the tall grass of the hayfield it seems likely that the mowed lawn constituted an evolutionarily novel ecological trap which made searching beetles conspicuous and easily captured by beetle-hunting birds.     

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.     

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．     

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.     

吹扫捕集气质联用法检测供水管网中消毒副产物——三氯乙醛

建立了供水管网中三氯乙醛的吹扫捕集/GC-MS检测方法.吹扫捕集与碱化反应同时进行,三氯乙醛完全快速转化为三氯甲烷,通过检测加碱前后管网水中三氯甲烷的含量,间接计算出管网水中三氯乙醛的含量.方法的线性范围为0～20μg/L,检出限为0.16μg/L,相对标准偏差<5%,平均回收率为90%～100%.     

Effect of Si on austenite stabilization,martensite morphology,and magnetic properties in Fe-26%Ni-x%Si alloys

The effect of Si on the austenite stabilization, martensite morphology, and magnetic properties in Fe-26%Ni-x%Si (x=3.5, 5, and 6) alloys have been studied by means of transmission electron microscopy (TEM) and M?ssbauer spectroscopy techniques. TEM observations reveal that the martensite morphology is closely dependent on the Si content. The volume fraction changes of martensite and austenite phases, the hyperfine magnetic field, and isomer shift values have been determined by Mssbauer spectroscopy. The M?ssbauer study reveals that the hyperfine magnetic field, the isomer shift values and the volume fraction of martensite decrease with increasing Si content.     

半透明多碱阴极浅氧敏化研究

根据多碱阴极理想模型:Na_3KSb+K_2CsSb+sb·Cs 偶极层,提出用 Cs_2O 取代 K_2CsSb+Sb·Cs 偶极层,很可能形成 p—n Na_2KSb—Cs_2O异质结光电阴极。用研制的氧发生器,以常规的碱金属源在超高真空系统中制备了 Na_2KSb,然后采用 NEA 光电阴极的激活工艺,用铯、氧交替激活 Na_2KSb,获得 p—n Na_2KSb—Cs_2O 光电阴极。结果表明,这种光电阴极在紫外—红外范围内具有较高的量子产额,其长波截止超过1.06um,达到1.1μm。     

微通道板的寿命试验

微通道板寿命时间是微通道板在应用中的一个重要质量指标。本文论述Ⅱ代象增强器的微通道板寿命试验的方法,在研制的试验装置上进行了试验研究,得到了微通道板的增盖—板压、增盖—输出电荷的变化规律,提出了进行寿命试验的规范和估算微通道板可能的工作寿命的方法。