Effects of the Crystal Diameter on the Dislocation Density in KCl Crystals Grown by the Czochralski Method

The dependence of dislocation density on the crystal diameter of the Czochralski grown KCl crystals (both pure and Sr doped) was investigated by the method of the etch pit and X-ray topograph. (1) The dislocation density drastically decreased with the decrease in diameter (D) for small D (D < 2 mm, Fig. 2). (2) The dislocation density in the Sr doped crystal was lower than that of pure component in the diameter examined. (3) Many helical dislocations and dislocation loops were observed in the thin crystals (D ∼ 0.5 mm) of the pure KCl and Sr doped one, respectively, by X-ray projection topography. These results were discussed in connection with the dislocation generation mechanisms due to thermal stresses or supersaturated point defects.     

Evaluation of the Intracellular Signaling Activities of κ-Opioid Receptor Agonists,Nalfurafine Analogs; Focusing on the Selectivity of G-Protein- and β-Arrestin-Mediated Pathways

Opioid receptors (ORs) are classified into three types (μ, δ, and κ), and opioid analgesics are mainly mediated by μOR activation; however, their use is sometimes restricted by unfavorable effects. The selective κOR agonist nalfurafine was initially developed as an analgesic, but its indication was changed because of the narrow safety margin. The activation of ORs mainly induces two intracellular signaling pathways: a G-protein-mediated pathway and a β-arrestin-mediated pathway. Recently, the expectations for κOR analgesics that selectively activate these pathways have increased; however, the structural properties required for the selectivity of nalfurafine are still unknown. Therefore, we evaluated the partial structures of nalfurafine that are necessary for the selectivity of these two pathways. We assayed the properties of nalfurafine and six nalfurafine analogs (SYKs) using cells stably expressing κORs. The SYKs activated κORs in a concentration-dependent manner with higher EC₅₀ values than nalfurafine. Upon bias factor assessment, only SYK-309 (possessing the 3S-hydroxy group) showed higher selectivity of G-protein-mediated signaling activities than nalfurafine, suggesting the direction of the 3S-hydroxy group may affect the β-arrestin-mediated pathway. In conclusion, nalfurafine analogs having a 3S-hydroxy group, such as SYK-309, could be considered G-protein-biased κOR agonists.     

Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes

An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.     

Extrinsic two dimensional excitons and their high density effects in BiI3 single crystals

Sharp absorption lines near the fundamental edge caused by planar stacking faults in BiI₃ crystals have been investigated on absorption and luminescence spectra. Under high excitation-photon densities these lines show peak-shift and line broadening. The high density effects on the exciton bound at the defects shows a two-dimensional feature of the exciton motion.     

Performance of software-based solar adaptive optics system

This paper reports the performance of our modified adaptive optics system for solar observations. This system operates at a frame rate of about 400 Hz and has the closed-loop cutoff frequency at 105 Hz. The results of the laboratory experiments show that this system compensates for a temporal wavefront-variation of less than 99 Hz and improves the Strehl ratio by a factor of five.     

Use of naphthalene as a solvent for selective formation of the 1:1 diels-alder adduct of C60 with anthracene

A reaction of C₆₀ with an equimolar amount of anthracene in refluxing naphtlhalene gives the 1:1 Diels-Alder adduct in 67% yield based on consumed C₆₀: the adduct was fully characterized by IR, UV-vis, ¹H and ¹³C NMR, and MS spectroscopy, and exhibited reversible reduction waves at the potential 0.11 to 0.19 V more negative and an irreversible oxidation peak at the potential 0.11 V less positive than those of C₆₀ itself.     

Search for sleptons and squarks at the Z0 peak in e-e+ colliders

We investigate single scalar lepton and scalar quark production processes $\text{e}{}^{\mathrm{-}}\text{e}{}^{\mathrm{+}}\text{→ Z}{}^0\text{→}\text{?}{}^{\mathrm{\pm }}\text{γ}\text{?}{}^{\mathrm{\pm }}\text{,}\text{q}\text{γ}\text{q}\text{and}\text{q}\text{g}\text{q}$ at the Z⁰ peak. We find that a detectable number of these scalars should be produced at the SLC and LEP-I colliders even if their masses substantially exceed the beam energy E = m_Z/2?45 GeV.