Probability densities of disorientation angles among randomly oriented grains in tricrystals

Journal of Materials Science - Orientation relationships of grains in tricrystals are discussed. Disorientation angles among grains are evaluated and a constrained condition of these around a...     

Dielectric properties of cellulose acylates

Thirteen kinds of cellulose acylates from the acetate to stearate were prepared by trifluoro acetic anhydride–fatty acid esterification, and their dielectric constant and loss were measured over wide temperature and frequency ranges. Two types of relaxation process (α_d and β_d) were recognized for all the acylates and an additional relaxation process (γ_d) was detected for the acylates with side chain length longer than that of the butyrate. These α_d to γ_d processes were attributed to the micro-Brownian motion of the main chain (α_d), the motion of oxycarbonyl group of the side chain (β_d) and the motion initiated by minimum three methylene groups in addition to the oxycarbonyl group (γ_d), respectively. In the transition map for the β_d process, inflection points were observed, and the temperature at the inflection point could be regarded as a freezing point of the micro-Brownian motion of the acyl side chain. In the temperature region above the inflection point, plots in transition map for all the acylates were found to be on the same straight line.     

Ion exchange resins and ethyleneimine polymer as antioxidants: I. Activity and mechanism

The antioxidant activity of ion exchange resins and ethyleneimine polymer was determined in methyl linoleate free from natural antioxidants and metals. Superior antioxidant activities were recognized in an ion exchange resin with NH groups and in the ethyleneimine polymer. The antioxidant activities in these heterogeneous reaction systems increased in linear proportion to the amount present. These antioxidant activities in the heterogeneous reaction system were mainly owing to their ability to donate hydrogen to the peroxy radicals produced in the autoxidation of methyl linoleate. The antioxidant radicals produced in these cases were very stable and generally couldn’t participate in the increase of the induction periods in the autoxidation of methyl linoleate by terminating the peroxy radicals. These results have never been obtained in the homogeneous reaction system but are characteristic in the heterogeneous one.     

Development for 4th generation mobile communications

The great success of the i‐mode service shows that data communication services are becoming accepted in the mobile communication world. Multimedia mobile communication services will be provided by 3rd generation IMT‐2000 systems next year in Japan. Thus, the time has come to begin the research and development for 4th generation (4G) mobile communication systems. There exist many difficult issues for 4G systems, such as frequency resources, additional investment, higher speed wireless transmission technology and so on. Furthermore, a new concept must be discussed for 4G before solving these issues. This paper briefly presents current conditions of cellular systems and the development of IMT‐2000 in Japan. The concept and problems of the 4G system are then described along with new technologies that will be useful in solving technical problems. Copyright © 2001 John Wiley & Sons, Ltd.