Bio-composite coatings, consisting of an organic matrix embedding a bioactive molecule, have been deposited by means of atomizer-assisted atmospheric pressure plasma. Ethylene was chosen as the precursor of the matrix, while the atomizer was fed with a water solution of lysozyme. Coatings chemical composition was investigated by XPS, FTIR and MALDI-TOF spectroscopies, and it has been proved that the one-step inclusion of protein domains in the composite coatings is successful and lysozyme chemical structure is only slightly altered. The amount of embedded lysozyme is as high as 14 mg/cm 2 as evaluated from water release test. Finally, the activity of the plasma-embedded protein is close to that of pure lysozyme as verified against Micrococcus lysodeikticus ATCC 4698 through an agar plate diffusion test.

Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and is superior to noble metals in natural abundance, cost, and compatibility with modern semiconductor fabrication processes. Ultrasmooth single-crystalline metallic films are beneficial for the fabrication of high-definition plasmonic nanostructures, especially complex integrated nanocircuits. The absence of surface corrugation and crystal boundaries also guarantees superior optical properties and applications in nanolasers. Here, we present UV to near-infrared plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam milling into an ultrasmooth single-crystalline aluminum film grown on a semiconducting GaAs substrate with a molecular beam epitaxy method. The single-crystalline aluminum film shows improved reflectivity and reduced two-photon photoluminescence (TPPL) due to the ultrasmooth surface. Both linear scattering and nonlinear TPPL are studied in detail. The nanoslit arrays show clear Fano-like resonance, and the nanoholes are found to support both photonic modes and localized surface plasmon resonance. We also found that TPPL generation is more efficient when the excitation polarization is parallel rather than perpendicular to the edge of the aluminum film. Such a counterintuitive phenomenon is attributed to the high refractive index of the GaAs substrate. We show that the polarization of TPPL from aluminum preserves the excitation polarization and is independent of the crystal orientation of the film or substrate. Our study gains insight into the optical property of aluminum nanostructures on a high-index semiconducting GaAs substrate and illustrates a practical route to implement plasmonic devices onto semiconductors for future hybrid nanodevices.

A monolithic current-mode pulse width modulation (PWM) step-down dc-dc converter with 96.7% peak efficiency and advanced control and protection circuits is presented in this paper. The high efficiency is achieved by "dynamic partial shutdown strategy" which enhances circuit speed with less power consumption. Automatic PWM and "pulse frequency modulation" switching boosts conversion efficiency during light load operation. The modified current sensing circuit and slope compensation circuit simplify the current-mode control circuit and enhance the response speed. A simple high-speed over-current protection circuit is proposed with the modified current sensing circuit. The new on-chip soft-start circuit prevents the power on inrush current without additional off-chip components. The dc-dc converter has been fabricated with a 0.6 m CMOS process and measured 1.35 mm 2 with the controller measured 0.27 mm 2 . Experimental results show that the novel on-chip soft-start circuit with longer than 1.5 ms soft-start time suppresses the power-on inrush current. This converter can operate at 1.1 MHz with supply voltage from 2.2 to 6.0 V. Measured power efficiency is 88.5-96.7% for 0.9 to 800 mA output current and over 85.5% for 1000 mA output current.

No abstract