Inelastic behaviour of polycrystalline metals under complex loading condition

In this paper, a simple mechanical model of polycrystal is suggested on the basis of the crystal plasticity. This model incorporates interactions among grains in polycrystal and interactions among slip systems in a crystal grain component. Especially, an equation for a slip strain of slip system is based on a theory of thermo-activation motion of dislocation. In this way, the model can take into account rate (creep) properties and temperature effects as well as an induced plastic anisotropy depending on deformation path, under multi-axial condition.Some computations are done by using the model for typical sets of strain paths and compared with corresponding experimental results of aluminum alloy at 200°C. The computational results reproduce accurately typical features observed in the experiments.     

Preparation and solution behavior of a thermoresponsive diblock copolymer of poly(ethyl glycidyl ether) and poly(ethylene oxide)

A thermoresponsive diblock copolymer, poly(ethyl glycidyl ether)-block-poly(ethylene oxide) (PEGE-b-PEO), is synthesized by successive anionic ring-opening polymerization of ethyl glycidyl ether and ethylene oxide using 2-phenoxyethanol as a starting material, and its solution behavior is elucidated in water. In a dilute 1 wt % solution, the temperature-dependent alteration in the polymer hydrodynamic radius (RH) is measured in the temperature range between 5 and 45 degrees C by pulse-gradient spin-echo NMR and dynamic light scattering. The RH value increased with temperature in two steps, where the first step at 15 degrees C corresponds to the core-shell micelle formation and the second step at 40 degrees C corresponds to the aggregation of the core-shell micelles. The formation of the core-shell micelles is supported by the solubilization of a dye (1,6-diphenyl-1,3,5-hexatriene) in the hydrophobic core, which is recognized for a copolymer solution in the temperature range between 20 and 40 degrees C. In this temperature range, the core-shell micelles and the unimers coexist and the fraction of the former gradually increases with increasing temperature, suggesting equilibrium between the micelles and the unimers. In the concentrated regime (40 wt % solution), the solution forms a gel and the small-angle X-ray scattering measurements reveal the successive formation of hexagonal and lamellar liquid crystal phases with increasing temperature.     

Synthesis of 8‐Oxoberbines and Related Benzolactams by Pd(OAc)2‐Catalyzed Direct Aromatic Carbonylation

A variety of alkoxy‐substituted benzolactams with a berbine or yohimbane skeleton were prepared from 1‐benzyl‐1,2,3,4‐tetrahydroisoquinolines or 1‐benzyl‐1,2,3,4‐tetrahydro‐β‐carbolines by a phosphine‐free Pd(II)‐catalyzed direct aromatic carbonylation in a Pd(OAc)₂‐Cu(OAc)₂ catalytic system. The site selectivity was compared with that of the carbonylation with Pd(OAc)₂ or Pd(OAc)₂·2 PPh₃, respectively.     

Total synthesis of plagiochin G and derivatives as potential cancer chemopreventive agents

A new and efficient total synthesis has been developed to obtain plagiochin G (22), a macrocyclic bisbibenzyl, and four derivatives. The key 16-membered ring containing biphenyl ether and biaryl units was closed via an intramolecular S_NAr reaction. All synthesized macrocyclic bisbibenzyls inhibited Epstein–Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells and, thus, are potential cancer chemopreventive agents.