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We have studied the crystallization of blended poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT). The effect of transesterification in the blend on crystallization has been examined by thermal analysis and optical microscopy. At higher temperatures above 200 C, the crystallization of one of the component (PBT) was enhanced by the existence of the crystals of another component (PET) for the intermediate degree of transesterification. The results indicate the importance of the details of the transesterification at molecular scale. and ethylene-acrylic acid copolymer 7 have been examined as blending polymers to improve the mechanical properties or gas permeability of PET. Poly(butylene terephthalate) (PBT) has also been studied as a blend polymer because of its softer mechanical property and faster crystallization than PET. 8,9 PET and PBT are miscible with each other and reactive by transesterification between the components.10-12 The process of transesterification has been examined by Fakirov et al. 10Backson et al.11 and Matsuda et al. 12 also studied the reaction by using NMR.The aim of this study is to analyze the crystallization process of the blend of PET/PBT by thermal analysis and by optical microscopy. It is known that PET and PBT crystallize separately in the miscible blend of PET/PBT. 13 It has also been reported that the crystallization of PET component is enhanced in the blend. 13,14 We examine the enhancement of crystallization behaviors of PET and PBT in the blend under the influence of different degrees of the reactive transesterification. EXPERIMENTAL Sample PreparationPET and PBT used for extruded films have intrinsic viscosities of 0.62 and 1.20 dl/g. PET was melted by a single screw extruder (60 mm screw diameter) at 285 C. PBT and two kinds of PET/PBT blended film (1/1 weight ratio) were prepared by the extruder at temperatures of 260 C (PBT), 260 and 295 C (EB260, EB295), respectively, at the residence time of 4 min. The melted polymer was molded into sheets on metal drum at 30 C. The thickness are 100-150 mm. Blended film was also made by solution casting (EBsol). Solutions of PET and PBT were prepared in phenol/tetrachloroethane of 6/4 (w/w), such that the total concentration of polymer was 5% (w/v) at room temperature. EBsol film of approximately 80 mm in thickness was obtained after the evaporation of solution at 23 C. MeasurementThermal behavior was examined by differential scanning calorimetry (TA Instrument, DSC Q100). Measurements were done by constant cooling and under isothermal conditions. The cooling rate was 5, 20 and 40 C/min after holding 1 min at 280 C. The isothermal condition was achieved by the cooling rate of 60 C/min after holding 1 min at 280 C. The crystallization process was also observed on a hot stage (LINKAM; model TH-600PH) at a cooling rate of 10 C/min by optical microscopy. Figure 1 shows the DSC thermograms at the cooling rates of 20 C/min. It is seen that the exothermic peaks of crystallization appear at higher temperatures in the order ...

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This study was performed to investigate the influence of changes in posture during feeding on masticatory efficiency. [Subjects] Subjects were 23 healthy young adults. [Methods] The subjects were asked to adopt four postures in a random order. The activity of the masseter muscle was recorded by electromyography from the beginning of chewing to the end. The number of chewing strokes, total chewing time, chewing rhythm and coefficient of variation of chewing rhythm were compared among the postures. [Results] The number of chewing strokes was significantly greater in R30-HN30 than in R90-HN0. The total chewing time was significantly longer in R30-HN0 and R30-HN30 than in R90-HN0. Burst duration was longest in R30-HN0. Cycle time was significantly longer in R30-HN0 than in R90-HN0. The coefficient of variation of burst duration was significantly greater in R30-HN0 than in R90-HN0. [Conclusion] Masticatory efficiency is the best in R90-HN0.

SELEX is a conventional method to obtain high affinity nucleic acids to target molecules. In this study, high affinity RNA molecules against SRP19 protein were selected by using a randomized library. The primary and predicted secondary structures of the aptamers are different from those of S-domain RNA which is the natural target of SRP19 protein. Comparison of structural features between S-domain RNA and aptamers might enhance our understanding on RNA-protein interaction.

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