2008 NOV 24 - (VerticalNews.com) -- According to a study from Cambridge, the United Kingdom, "Polyelectrolyte brushes with electroactive counterions provide an effective platform for surfaces with electrochemically switchable wetting properties. Polycationic poly(2-(methacryloyloxy)-ethyl-trimethyl-ammonium chloride) (PMETAC) brushes with ferricyanide ions ([Fe(CN)(6)](3-)) were used as the electrochemically addressable surface."

  "After a negative potential of -0.5 V was applied to the [Fe(CN)(6)](3-)-coordinated PMETAC brushes, the [Fe(CN)(6)](3-) species were reduced to [Fe(CN)(6)](4-), and the surface became more hydrophilic. By application of alternating negative and positive potentials, PMETAC brushes were switched reversibly between the reduced state ([Fe(CN)6]4-) and oxidized state ([Fe(CN)(6)](3-)), resulting in reversible changes in water contact angles. The time required for a complete contact angle change can be tuned from 1 to 20 s, by changing the brush thickness and the concentration of supporting electrolyte. We present an electrochemical brush transport model that includes the electrochemical reaction at the charged electrode and describes ion transport through the brush phase covering the electrode. The model quantitatively describes the response of the contact angle (hydrophilicity) to the applied voltage as a function of background ionic strength and brush thickness, supporting the proposed mechanism of ion transport through the brush and electrochemical reaction at the electrode," wrote E. Spruijt and colleagues, University of Cambridge ...read more

  2008 NOV 24 - (VerticalNews.com) -- "A new experimental set-up was developed to evaluate the strain dependence of critical current (I-c(epsilon(a))) for YBa2Cu3O7-delta (YBCO)-coated conductors under a magnetic field in a variable temperature environment. In this paper, we report the first results on the effect of a magnetic field parallel to the c axis (B parallel to c) on I-c(epsilon(a)) up to 10 T at temperatures of 60-77 K. We found that the magnetic field affects I-c(epsilon(a)) in a different manner, depending on the field region," scientists writing in the journal Superconductor Science & Technology report ...read more

  2008 NOV 24 - (VerticalNews.com) -- "Embedded system technology can improve electrical performance and reduce assembly cost compared with those discrete component technologies. In this paper, simulation and characterization of embedded capacitors will be presented," researchers in Seoul, South Korea report.

  "The embedded capacitors were simulated and characterized employing eight layered printed circuit boards. Fabrication process of multilayer embedded capacitors will be presented. Theoretical Considerations regarding the embedded capacitors have been paid to understand the frequency dependent impedance behavior. Frequency dependent impedances, capacitances, and quality-factors of fabricated embedded capacitors were investigated. As a result, parasitic inductance was developed mainly through via holes and it has almost same value regardless of different capacitances. Frequency dependent capacitance values of fabricated embedded capacitors were well matched with those of simulated embedded capacitors," wrote H.W. You and colleagues, Kwangwoon University ...read more