Photoindentation: A New Route to Understanding Dislocation Behavior in Light.

It was recently found that extremely large plasticity is exhibited in bulk compression of single-crystal ZnS in complete darkness. Such effects are believed to be caused by the interactions between dislocations and photoexcited electrons and/or holes. However, methods for evaluating dislocation behavior in such semiconductors with small dimensions under a particular light condition had not been well established. Here, we propose the "photoindentation" technique to solve this issue by combining nanoscale indentation tests with a fully controlled lighting system. The quantitative data analyses based on this photoindentation approach successfully demonstrate that the first pop-in stress indicating dislocation nucleation near the surface of ZnS clearly increases by light irradiation. Additionally, the room-temperature indentation creep tests show a drastic reduction of the dislocation mobility under light. Our approach demonstrates great potential in understanding the light effects on dislocation nucleation and mobility at the nanoscale, as most advanced technology-related semiconductors are limited in dimensions.

Synthesis of quinolinomorphinan derivatives as highly selective δ opioid receptor ligands.

We have reported previously the novel δ opioid agonist KNT-127 which showed high affinity and selectivity for the δ receptor. Moreover, the analgesic effect of subcutaneously administered KNT-127 was more potent than that of a prototypical δ agonist (-)-TAN-67 in the acetic acid writhing test. This study of the structure-activity relationship of KNT-127 derivatives focused on the introduction of substituents onto the 5'-, 6'-, 7'- or 8'-position of the quinoline ring and revealed that many derivatives with 5'- or 8'-substituents showed high affinities and selectivities for the δ receptor. Especially, SYK-153 with an 8'-OH group showed the highest affinity and the most balanced and highest selectivity for the δ receptor among the synthesized compounds.

Design and synthesis of KNT-127, a δ-opioid receptor agonist effective by systemic administration.

We have reported previously the novel δ-opioid agonist, SN-28, which was more potent in in vitro assays than the prototype δ-agonists, TAN-67 and SNC-80. However, when administered by subcutaneous injection, this compound showed no analgesic effect at dosages greater than 30mg/kg in the acetic acid writhing test. We speculated that SN-28 was not effective in the test because the presence of the charged ammonium groups prevented its penetration through the blood-brain barrier. On the basis of our proposal, we designed the novel δ-agonist, KNT-127, which was effective with systemic administration.