Abstract: By patterning a catalyst layer in a micrometer scale and growing nanotubes on it, the emission area is formed by many small emitter islands. Each emitter island comprises finite randomly aligned nanotubes in a nominal density. Due to the vast number of gaps between emitter islands, relatively more nanotubes are exposed to the edge region of the emitter, which effectively increases the average inter-spacing of nanotubes. The field shielding effect is significantly reduced this way.

Abstract: A method for synthesizing extended poly(amino acids) conjugated to imaging agents, such as DTPA, is disclosed. The amino acid is initially conjugated to the imaging agent at the monomer stage, followed by formation of the corresponding N-carboxyanhydride. The method utilizes catalyzed ring opening polymerization of the N-carboxyanhydride of the amino acid-imaging agent monomer allowing the formation of a poly(amino acid) backbone having 100% imaging agent conjugation if desired. However, the present method also permits the degree of conjugation to be controlled by copolymerizing the N-carboxyanhydride of the amino acid-imaging agent monomer with one or more unconjugated monomers, i.e. N-carboxyanhydrides of the same or of other amino acids. Various imaging agents may be employed, and new hybrid random, block, and mixed copolymers may be prepared.

Abstract: Mixed alkali metal salts of phosphoric acid in combination with a co-catalyst such as tetramethylammonium hydroxide (TMAH) are excellent transesterification catalysts for use in the preparation of polycarbonate from bisphenol A and diphenyl carbonate. The mixed alkali metal phosphate salts were shown by kinetic measurements made on a model system composed of p-tert-octylphenol and bis(p-cumylphenyl) carbonate to be inherently more potent catalysts than salts of phosphoric acid comprising a single alkali metal ion. In addition to providing higher rates of polymerization, the new catalysts were shown to provide polycarbonates containing reduced levels of Fries rearrangement product relative to polymerization reactions catalyzed by conventional catalyst systems such as sodium hydroxide together with TMAH co-catalyst.

Abstract: Mixed alkali metal salts of phosphoric acid in combination with a co-catalyst such as tetramethylammonium hydroxide (TMAH) are excellent transesterification catalysts for use in the preparation of polycarbonate from bisphenol A and diphenyl carbonate. The mixed alkali metal phosphate salts were shown by kinetic measurements made on a model system composed of p-tert-octylphenol and bis(p-cumylphenyl) carbonate to be inherently more potent catalysts than salts of phosphoric acid comprising a single alkali metal ion. In addition to providing higher rates of polymerization, the new catalysts were shown to provide polycarbonates containing reduced levels of Fries rearrangement product relative to polymerization reactions catalyzed by conventional catalyst systems such as sodium hydroxide together with TMAH co-catalyst.