Acoustic Control of an Impinging Planar Jet upon a Wedge

Active control of an impinging jet upon a wedge has been attempted using a sinusoidal excitation of blowing and sucking at the jet exit. The excitation sufficiently enables 'phase-lock', which is synchronization between self-oscillating flow and the excitation, so that hot-wire measurements directly provide phase averaged flow fields and they illustrate appearance of the jet swing in front of the wedge and collision of the jet on one of side of the wedge. It was demonstrated that this control set up is practical not only for illustration of the phase averaged flow field but also for reduction of the edge tone due to the flow oscillation with inverse phase excitation in half of the jet.ArticleJournal of Fluid Science and Technology. 3(2):274-281 (2008)journal articl

Analyzing the effects of surface distribution of pores in cell electroporation for a cell membrane containing cholesterol

This paper presents a model and numerical analysis (simulations) of transmembrane potential induced in biological cell membrane under the influence of externally applied electric field (i.e., electroporation). This model differs from the established models of electroporation in two distinct ways. Firstly, it incorporates the presence of cholesterol (~20% mole-fraction) in biological membrane. Secondly, it considers the distribution of pores as a function of the variation of transmembrane potential from one region of the cell to another. Formulation is based on the role of membrane tension and electrical forces in the formation of pores in a cell membrane, which is considered as an infinitesimally thin insulator. The model has been used to explore the process of creation and evolution of pores and to determine the number and size of pores as a function of applied electric field (magnitude and duration). Results show that the presence of cholesterol enhances poration by changing the membrane tension. Analyses indicate that the number of pores and average pore radii differ significantly from one part of the cell to the other. While some regions of the cell membrane undergo rapid and dense poration, others remain unaffected. The method can be a useful tool for a more realistic prediction of pore formation in cells subjected to electroporation.Comment: 11 pages, 3 figures. v2: added new references, grammatical changes, corrected typo

Morphology of graphene thin film growth on SiC(0001)

Epitaxial films of graphene on SiC(0001) are interesting from a basic physics as well as applications-oriented point of view. Here we study the emerging morphology of in-vacuo prepared graphene films using low energy electron microscopy (LEEM) and angle-resolved photoemission (ARPES). We obtain an identification of single and bilayer of graphene film by comparing the characteristic features in electron reflectivity spectra in LEEM to the PI-band structure as revealed by ARPES. We demonstrate that LEEM serves as a tool to accurately determine the local extent of graphene layers as well as the layer thickness

Energetics and structure of the lower E region associated with sporadic E layer

The electron temperature (<I>T<sub>e</sub></I>), electron density (<I>N<sub>e</sub></I>), and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (<I>E<sub>s</sub></I>) at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from <I>N<sub>e</sub></I> and <I>T<sub>e</sub></I> shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of <I>E<sub>s</sub></I>, that was drawn by using <I>T<sub>e</sub></I>, <I>N<sub>e</sub></I>, and the electric field data, corresponded to the computer simulation; the main structure of <I>E<sub>s</sub></I> is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of <I>T<sub>e</sub></I>, <I>N<sub>e</sub></I> and electric field in higher altitude