区域地下水持续开发利用的风险分析研究

根据区域水源情况由于各地区的地形、地质、水文地质等条件存在差异，以及区域地下水资源开发利用规划管理特点不同，决定了它存在一定程度的不确定性和不准确因素的情况，探讨了区域地下水开发利用的可持续性理念，以及造成不可持续的原因及其后果，并提出了进行地下水不可持续的风险定量分析的可行方案．     

Optical nano-imaging of gate-tunable graphene plasmons

The ability to manipulate optical fields and the energy flow of light is central to modern information and communication technologies, as well as quantum information processing schemes. However, because photons do not possess charge, a way of controlling them efficiently by electrical means has so far proved elusive. A promising way to achieve electric control of light could be through plasmon polaritons—coupled excitations of photons and charge carriers—in graphene. In this two-dimensional sheet of carbon atoms, it is expected that plasmon polaritons and their associated optical fields can readily be tuned electrically by varying the graphene carrier density. Although evidence of optical graphene plasmon resonances has recently been obtained spectroscopically, no experiments so far have directly resolved propagating plasmons in real space. Here we launch and detect propagating optical plasmons in tapered graphene nanostructures using near-field scattering microscopy with infrared excitation light. We provide real-space images of plasmon fields, and find that the extracted plasmon wavelength is very short—more than 40 times smaller than the wavelength of illumination. We exploit this strong optical field confinement to turn a graphene nanostructure into a tunable resonant plasmonic cavity with extremely small mode volume. The cavity resonance is controlled in situ by gating the graphene, and in particular, complete switching on and off of the plasmon modes is demonstrated, thus paving the way towards graphene-based optical transistors. This successful alliance between nanoelectronics and nano-optics enables the development of active subwavelength-scale optics and a plethora of nano-optoelectronic devices and functionalities, such as tunable metamaterials, nanoscale optical processing, and strongly enhanced light–matter interactions for quantum devices and biosensing applications.     

Tubuloreticular structures in chicken bursa Fabricii lymphocytes

Summary Tubuloreticular structures were observed in bursal lymphocytes of a 12-day-old male chicken. These structures are often observed in mammalian lymphocytes and endothelial cells. Their presence in bursal lymphocytes confirm their association with B-lymphocytes.We are grateful to Dr. J.L.F. Cristina Afonso for material support, to Mrs M. Lapão and J.P. Cristina Afonso for thier technical help, and to the Freixial Poultry Industry for providing the chickens.     

ASMWIN在镇江市地下水渗流模拟中的应用

随着人口的增长、工农业生产的发展和人们生活水平的提高,对地下水资源的需求量不断增加.地下水的运动方式是地下水在岩土空隙中的渗透流动,简称渗流.加强对地下水渗流的分析和研究,进行地下水资源评价和地下水变化趋势的预测,对指导地下水的合理开发利用及确保地下水供水工程安全等是非常重要的.目前,地下水水流模拟的研究方法很多,分别适用于不同的水文地质条件.作者采用的是德国的ASMWIN软件,它对二维地下水水流和污染质运移过程的模拟具有较高的可靠性,而镇江市孔隙潜水的水流为二维流动问题.故将该方法应用于镇江市地下水水流模拟,研究结果表明,该软件操作方便,求解结果与实际的水文地质条件高度一致,具有广泛的应用前景.