科研成果 by Year: 2008

An oligo(o-phenyleneethynylene-alt-p-phenyleneethynylene) was synthesized to create a conjugated molecule capable of adopting a helical secondary structure. A special feature of such a folded molecule is that the effective directions of energy/charge transport via covalent conjugation and through pi-pi stacking are converged to be along the helix axis. The transition from random conformations to the helix, driven by solvophobic and aromatic stacking interactions, was controlled by solvent properties. UV-vis and fluorescence spectroscopies gave supportive evidence for the folding process.

In an infinite-horizon model with Marshallian time preferences, foreign aid, foreign borrowing, and domestic capital accumulation, this paper reexamines the effects of foreign aid on domestic capital accumulation and foreign borrowing. Comparative static analysis shows that a permanent increase in foreign aid leads to an increase in both long-run capital accumulation and domestic consumption, but a decrease in foreign borrowing. Short-run analysis shows that both a permanent and a temporary increase in foreign aid makes people more patient, which leads to a rise in investment and a reduction in foreign borrowing initially.

Single-walled carbon nanotube field-effect transistors (SWCNT FETs) with multi-walled carbon nanotubes (MWCNTs) as interconnects were fabricated, and their field effect properties were measured and compared with those of the case with metal leads as interconnects. Both cases showed almost the same direct current (DC) response, while the MWCNTs interconnected case showed a little better alternating current (AC) properties. AC measurement showed that the MWCNTs interconnected SWCNT FETs worked well at frequency up to 20 MHz.