We report the results of theoretical studies on the self-assembled monolayers of benzenethiolate (BT) and benzyl mercaptide (BZM) on a Au(111) surface. A few relevant potential energy parameters were determined. We have performed annealing type molecular dynamics simulations where the minimized initial configurations are heated to 1000 K and then cooled to room temperature, assuming two types of unit cells:  √3 × √3R30° and 2 × 2. The results of the simulations showed that BZM formed a nearly perfect herringbone structure, while the apparent herringbone type structure of BT was somewhat disordered in the √3 × √3R30° unit cell. For the 2 × 2 unit cell with larger area per molecule, both monolayers did not form well-ordered structures, but the BZM showed some local ordering with herringbone structure. In both cases, the molecules of BZM are found to be nearly vertical to the surface, while those of BT are tilted from the surface normal. All these theoretical results are consistent with recent experimental findings. The role of a flexible methylene unit near the sulfur headgroup in discriminating stable packing structures of the self-assembled monolayers is discussed.

Electronic transport characteristics of electrolyte-gated conducting polyaniline nanowire field-effect transistors Appl. Phys. Lett. 95, 013113 (2009); 10.1063/1.3176444 Ambipolar field-effect transistor based on organic-inorganic hybrid structure

Mat and liquid-type electric insecticide vaporizers continuously emit insecticides into the surrounding air. Because both the target insects, mostly mosquitoes, and humans are exposed to those insecticides, it is crucial to understand and monitor their deposition and spatial distribution in treated areas. In the current study, we examined the evaporation of insecticides from seven commercial liquid and mat vaporizers and measured their knock-down and insecticidal activity against the adult females of the Asian tiger mosquito, Aedes albopictus (Skuse). Electric vaporizers from three manufactures had differences in their heaters and active ingredients. Most had continued evaporation during hourly and daily monitoring; however, some liquid vaporizers failed to continue emission to their designated end periods. Overall, mosquitoes located at the upper position in a Peet-Grady chamber and in a field-simulation room exhibited faster knock-down activity than did mosquitoes in other areas, indicating that the insecticides accumulated on the ceiling area. Although most of mat and liquid vaporizers had <60 min of average KT90 values when tested in the Peet-Grady chamber (1.8 × 1.8 × 1.8 m), they failed to have any knock-down in 2 h of observation in the field-simulation room (6.8 × 3.4 × 2.7 m) but showed 72. 8 ± 11.7% and 56. 7 ± 7.3% knock-down in the mat and liquid vaporizers, respectively, in 3 h of operation. Further study will be required to examine whether this relatively limited efficacy can be compensated by other physiological and behavioral effects, including disruption in host-seeking or blood-sucking activities.