Search

The synthesis of an ionic quaterrylenebis(dicarboximide) 1a, a long-wavelength absorbing mesogen, is described. When compared with its analogue 2a, an ionic perylenebis(dicarboximide), the aromatic protons of la exchange with deuterium of concentrated D2SO4 at a dramatically faster rate. In addition, stronger aggregation in aqueous media was observed for 1a. [ABSTRACT FROM AUTHOR]

We investigated the usefulness of hydrocarbons and 2-alkylcyclobutanones as markers for irradiated, dried shrimps. A method was developed to detect the irradiation of dried shrimps (Penaeus aztecus) by identifying radiation-induced hydrocarbons and 2-alkylcyclobutanones extracted from dried shrimps, which were separated by Florisil column chromatography and identified by a method using gas chromatography/mass spectrometry. Radiation-induced hydrocarbons and 2-alkylcyclobutanones are formed from the fatty acids of the irradiated fats. The quantity of the hydrocarbons and 2-alkylcyclobutanones formed from some fatty acids is related to the composition of fatty acids in a sample. The concentrations of hydrocarbons and 2-alkylcyclobutanones increased with radiation dose. The major hydrocarbons in the irradiated, dried shrimps were 1tetradecene and pentadecane from palmitic acid; small amounts of heptadecane and 1-hexadecene from stearic acid; and 8heptadecene and 1,7-hexadecadiene from oleic acid. 2-(5'-Tetradecenyl)cyclobutanone, one of the 2-alkylcyclobutanones, was present at the highest concentration. The radiation-induced hydrocarbons and 2-alkylcyclobutanones were detected at radiation doses of 0.5 kGy and greater. These compounds were not detected in nonirradiated, dried shrimps. [ABSTRACT FROM AUTHOR]

Application of carbon nanotubes to various electronic devices such as field emission displays, gas sensors, and nanotransistors have been hampered by difficulties in control of electronic properties that are determined by the chirality and diameter of carbon nanotubes. A selective etching process may become an alternative to select nanotubes that have appropriate electronic properties. This article demonstrates that selective etching with carbon dioxide (CO[sub2]) provides a route to single-wall carbon nanotube (SWNT) of specific chirality. Investigations on adsorption of CO[sub2] molecules were carried out at various sites in armchair and zigzag tube edges. The study concludes that high selectivity in adsorption of CO[sub2] molecule on tube edges of different structures can be used to control electronic properties of SWNT. The result from density functional calculations provides a clue to the control of the electronic properties of SWNT. CO[sub2] molecule physisorbs on an armchair tube edge, whereas strongly chemisorbs on a zigzag tube edge with large adsorption of energy.