Electrical properties of breast cancer cells from impedance measurement of cell suspensions

Impedance spectroscopy of biological cells has been used to monitor cell status, e.g. cell proliferation, viability, etc. It is also a fundamental method for the study of the electrical properties of cells which has been utilised for cell identification in investigations of cell behaviour in the presence of an applied electric field, e.g. electroporation. There are two standard methods for impedance measurement on cells. The use of microelectrodes for single cell impedance measurement is one method to realise the measurement, but the variations between individual cells introduce significant measurement errors. Another method to measure electrical properties is by the measurement of cell suspensions, i.e. a group of cells within a culture medium or buffer. This paper presents an investigation of the impedance of normal and cancerous breast cells in suspension using the Maxwell-Wagner mixture theory to analyse the results and extract the electrical parameters of a single cell. The results show that normal and different stages of cancer breast cells can be distinguished by the conductivity presented by each cell. © 2010 IOP Publishing Ltd

Transition behavior of k-surface from hyperbola to ellipse

The transition behavior of the k-surface of a lossy anisotropic indefinite slab is investigated. It is found that, if the material loss is taken into account, the k-surface does not show a sudden change from hyperbola to the ellipse when one principle element of the permittivity tensor changes from negative to positive. In fact, after introducing a small material loss, the shape of the k-surface can be a combination of a hyperbola and an ellipse, and a selective high directional transmission can be obtained in such a slab

The Valuation of Service of Recreation Function of Dalinor National Natural Reserve

Dalinor National Natural Reserve is located in the west of Keshketeng Banner of Chifeng City, Inner Mongolia Autonomous Region (IMAR). It covers a total area of 119,413.35 ha, and is in drought or semi-drought continental climatic zone. DNNR is a comprehensive natural reserve made up of different ecosystems including lakes, prairies, wetlands, and forests. Dalinor Lake in DNNR is regarded as the paradise of birds, covering an area of 238 km2 between sandy lands and grasslands. DNNR was established in 1987 as a provincial natural reserve and was upgraded to a National Natural Reserve by the State Council of China in 1997. DNNR not only serves as an ideal resort for eco-tourism but also serves as an important scientific research base. The value of service of recreation function of DNNR depends heavily on the environmental quality that offers tourists various ecosystem amenities and opportunities for viewing wild plants and animals. So it is meaningful to value the recreation function of DNN

Valley-Hall Kink and Edge States in Multilayer Graphene

We report on a theoretical study of one-dimensional (1D) states localized at few-layer graphene system ribbon edges, and at interfaces between few-layer graphene systems with different valley Hall conductivities. These 1D states are topologically protected when valley mixing is neglected. We address the influence on their properties of stacking arrangement, interface structure, and external electric field perpendicular to the layers. We find that 1D states are generally absent at multilayer ribbon armchair direction edges, but present irrespective of crystallographic orientation at any internal valley-Hall interface of an ABC stacked multilayer.Comment: 5 pages, 3 figure

A note on the discovery of absorption features in 1E 1207.4-5209

In a paper by Sanwal et al. (2002), it is supposed to be very difficult to interpret the absorption features in term of cyclotron lines. However, we would like to address here that the possibility of the absorption being cyclotron resonance can not be ruled out.We propose that the isolate neutron star, 1E 1207.4-5209 in the center of supernova remnant PKS 1209-51/52, has a debris disk and is in a propeller phase, with an accretion rate 6x10^{-11} M_solar/year.Comment: 4 page and 1 figure, revised substantially, or at http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.ht

Momentum-space electronic structures and charge orders of high-temperature superconductors Ca2-xNaxCuO2Cl2 and Bi2Sr2CaCu2O8+delta

We study the electronic structure of Ca2-xNaxCuO2Cl2 and Bi2Sr2CaCu2O8+d samples in a wide range of doping, using angle-resolved photoemission spectroscopy, with emphasis on on the Fermi surface (FS) in the near anti-nodal region. The "nesting wave vector", i.e., the wave vector that connects two nearly flat pieces of the Fermi surface in the anti-nodal region, reveals a universal monotonic decrease in magnitude as a function of doping. Comparing our results to the charge order recently observed by scanning tunneling spectroscopy (STS), we conclude that the FS nesting and the charge order pattern seen in STS do not have a direct relationship. Therefore,the charge order likely arises due to strong correlation physics rather than FS nesting physics.Comment: 6 pages, 4 figure