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Comparing with the metal-oxide-semiconductor field-effect transistor (MOSFET), the switching frequency of the gallium nitride enhancement mode high electron mobility transistor (GaN E-HEMT) can be significantly increased. However, the impacts of parasitic inductance and capacitance to the circuit performance should be taken into account for design considerations. In this paper, the gate drive circuit design for GaN E-HEMT is described in detail. The effectiveness of the design considerations is fully examined by the simulation software, LTSPICE with GaN E-HEMT model introduced by Efficient Power Conversion (EPC). From the simulation results, the parasitic effects caused by the parasitic components can be clearly observed. Thus, the simulation results can provide the insight of practical design. Finally, a buck converter with 1 MHz switching frequency is built according to these design considerations.

Carbohydrates are the largest natural carbon source when compared to lignin, fatty acids, proteins and other biomass resources. One carbohydrate dehydration product, 5-hydroxymethylfurfural (HMF), is a versatile platform chemical used to derive a number of important C6 compounds, including 2,5-furandicarboxylic acid (FDCA), 2,5-dimethylfuran (DMF), 2,5-diformylfuran (DFF), adipic acid, caprolactone and levulinic acid. Due to structural similarity, FDCA could replace petrochemical-purified terephthalic acid (PTA) for the synthesis of bio-based polyesters to be used for the fabrication of plastic bottles, fibres and films. The oxidation product of HMF, FDCA, is among the original United States Department of Energy's top twelve value-added building blocks. HMF was not on the list because of its lack of high synthetic selectivity and yield. HMF is reactive and can undergo conversion to levulinic acid, humin and other by-products during the dehydration process. Dehydration technology of carbohydrates into HMF has improved since then; in particular, higher yields were realized in ionic liquid media. It is on the ‘Top10 + 4’ revised list of bio-based product opportunities from carbohydrates. This chapter describes the current progress on HMF formation by dehydration of carbohydrates and sugars as well as one-pot direct synthesis of HMF form lignocellulose in ionic liquids.

A low-temperature solution approach (90-95 degrees C) using FeCl(3) and urea was carried out to synthesize beta-FeOOH nanorods in aqueous solution. The as-synthesized beta-FeOOH nanorods were further calcined at 300 degrees C to form porous nanorods with compositions including both beta-FeOOH and alpha-Fe(2)O(3). The derived porous nanorods were engineered to assemble with four layers of polyelectrolytes (polyacrylic acid (PAA)/polyethylenimine(PEI)/PAA/PEI) on their surfaces as polyelectrolyte multilayer nanocapsules. Fluorescein isothiocyanate (FITC) molecules were loaded into the polyelectrolyte multilayer nanocapsules in order to investigate drug release and intracellular delivery in Hela cells. The as-prepared nanocapsules showed ionic strength-dependent control of the permeability of the polyelectrolyte shells. The release behavior of the entrapped FITC from the FITC-loaded nanocapsules exhibited either controlled- or sustained-release trends, depending on the compactness of the polyelectrolyte shells on the nanorod surfaces. Cytotoxicity measurements demonstrate that the native nanorods and the polymer-coated nanorods have excellent biocompatibility in all dosages between 0.1 ng mL(-1) and 100 microgm L(-1). The time dependence of uptake of FITC-loaded nanocapsules by Hela cancer cells observed by laser confocal microscopy indicates that the nanocapsules can readily be taken up by cancer cells in 15 min, a relatively short period of time, while the slow release of the FITC from the initial perimembrane space into the cytoplasm was followed by release into the nucleus after 24 h.