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A theoretical approach for predicting the attenuation of microwave propagation in sandstorms is presented, with electric charges generated on the sand grains taken into account. It is found that the effect of electric charges distributed partially on the sand surface is notable. The calculated attenuation is in good agreement with that measured in certain conditions. The distribution of electric charges on the surface of sand grains, which is not easy to measure, can be approximately determined by measuring the attenuation value of electromagnetic waves. Some effects of sand radius, dielectric permittivity, frequency of electromagnetic wave, and visibility of sandstorms on the attenuation are also discussed quantitatively. Finally, a new electric parameter is introduced to describe the roles of scattering, absorption and effect of charges in attenuation. [ABSTRACT FROM AUTHOR]

The anticancer activity of anti-bacterial cecropins makes them potentially useful as peptide anti-cancer drugs. We used the cell-attached patch to study the effect of cecropin B (CB; having one hydrophobic and one amphipathic α-helix) and its derivative, cecropin B3 (CB3; having two hydrophobic α-helices) on the membrane of Ags cancer cells. Application of 10–60 µM CB onto the membrane of the cancer cell produces short outward currents. Comparative study with CB3, which induces no outward currents, shows that the amphipathic group of CB is necessary for the pore formation. The results provide a rationale to study the cell-killing activity of antimicrobial peptides at the single cancer cell level. [ABSTRACT FROM PUBLISHER]

We report a phonon transport model for a bulk thermoelectric material to investigate the effect of the grain diameter and the grain-boundary thickness on its thermal conductivity. The analysis results display that the bulk thermal conductivity is significantly reduced by decreasing the grain sizes when the grain diameter is less than 500 nm, which provides us one feasible way to enhance the figure of merit ZT of the material, and the thermal conductivity is mainly attributed to the contribution of grains, while the grain-boundary thermal conductivity has to be considered when the grain diameter is less than 100 nm. [ABSTRACT FROM AUTHOR]