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921.
Lisman?SuryanegaraEmail author Hiroaki?Okumura Antonio?Norio?Nakagaito Hiroyuki?Yano 《Cellulose (London, England)》2011,18(3):689-698
This study evaluates the effects of nucleants phenylphosphonic acid zinc (PPA-Zn) and talc, mold temperature, and microfibrillated
cellulose (MFC) reinforcement in the acceleration of injection molding cycle of polylactic acid (PLA). PLA was dissolved in
an organic solvent, mixed with nucleant and MFC, and dried compounds were injection molded into molds at temperatures ranging
from 40 °C to 95 °C and holding times from 10 s to 120 s. Our results showed that PPA-Zn is more effective nucleating agent
compared to talc. The addition of 1 wt% PPA-Zn and the mold temperature of 95 °C exhibited the fastest crystallization rates
for the molded PLA, however, at this temperature the parts could not be quickly ejected without distortion. Addition of 10 wt%
MFC increased the stiffness of PLA at high temperatures and allowed ejection of parts without distortion at a holding time
of just 10 s. At this holding time, the crystallinity of the PLA composite was 15.3% but the storage modulus above T
g
was superior to that of fully crystallized neat PLA due to MFC reinforcement, retaining the shape of the molded part during
demolding. The mechanical properties of the composite at room temperature were also higher than those of fully crystallized
neat PLA. 相似文献
922.
This review describes the results from X-ray Absorption Spectroscopy studies that have contributed to an understanding of the role of Ca in the photosynthetic water-oxidation reaction. The results include the first Mn, Ca and Sr X-ray spectroscopy studies using Ca or Sr-substituted PS II samples that established the presence of a MnCa heteronuclear structure and its orientation, and the most recent Sr X-ray spectroscopy study using biosynthetically prepared Sr-containing PS II in the various S-states that provide important insights into the requirement for Ca in the mechanism of the Mn(4)Ca catalytic center. 相似文献
923.
Wuttikul C Taoka T Akashi T Nakagawa H Miyasaka T Sakamoto M Takayama K Wada T Kitano S Takahama J Marugami N Kichikawa K 《Magnetic resonance imaging》2008,26(10):1374-1380
Purpose
This study discusses prominent signal intensity of T1/T2 prolongation of subcortical white matter within the anterior temporal region in premature infant brains that radiologists may encounter when interpreting conventional screening MRIs.Materials and Methods
T1- and T2-weighted images of 69 preterm and term infants with no neurological abnormalities or developmental delays were evaluated retrospectively for areas of prominent signal intensity of T1/T2 prolongation in white matter. We measured signal intensities of anterior temporal white matter, deep temporal white matter, frontopolar white matter and subcortical white matter of the precentral gyrus. We accessed chronological changes in signal intensity in the anterior and deep temporal white matter. We also analyzed variance tests among the signal intensity ratios to the ipsilateral thalamus of white matter areas by gestational age.Results
There was high frequency of prominent signal intensity of T1/T2 prolongation in the temporal tip, particularly at a gestational age of 36–38 weeks. Signal intensity ratio of the anterior temporal white matter was lower on T1-weighted images and higher on T2-weighted images, and the finding became less prominent with increasing gestational age. The signal intensity ratios of anterior temporal white matter at a gestational age of 36–37 weeks and 38–39 weeks were significantly different from other regions.Conclusion
Prominent signal intensity of T1/T2 prolongation of subcortical white matter of the anterior temporal region is seen in normal premature infants, especially those at 36–39 gestational weeks. Although it is a prominent finding, radiologists should understand that these findings do not represent a pathological condition. 相似文献924.
Yano K Sakakibara T Tayama T Yokoyama M Amitsuka H Homma Y Miranović P Ichioka M Tsutsumi Y Machida K 《Physical review letters》2008,100(1):017004
To identify the superconducting gap structure in URu2Si2, we perform field-angle-dependent specific heat measurements for the two principal orientations in addition to field rotations, and a theoretical analysis based on microscopic calculations. The Sommerfeld coefficient gamma(H)'s in the mixed state exhibit a distinctly different field dependence. This comes from point nodes and the substantial Pauli paramagnetic effect of URu2Si2. These two features combined give rise to a consistent picture of superconducting properties, including a possible first order transition of Hc2 at low temperatures. 相似文献
925.
Poly(vinylidene fluoride) (PVDF) was incorporated in situ with silica by a sol-gel process involving tetraethoxysilane. The mechanical properties of these in situ hybrids were compared with those of PVDF composites mechanically blended with 14-nm diameter fumed silica particles. The ultimate strength of the in situ hybrids was higher than that of the blend composites, since fumed silica particles aggregate and act as mechanically weak points. The thermal analysis, dynamic viscoelastic properties, and dielectric properties were compared. The β-relaxation of PVDF caused by the glass transition was observed at around −40°C in the differential scanning calorimetry (DSC) and the mechanical tan δ curves and at −30°C in the dielectric loss factor (ϵ”) curve. The αc-relaxation due to the molecular motion in the crystalline phase occurred at 61°C in DSC curve, at 100°C in the tan δ curve, and at 80°C in the ϵ” curve. The peak positions of these relaxations did not change, but the peak intensities were decreased with the increase in silica content for both the in situ hybrids and blend composites. The activation energies for PVDF were calculated as 136 kJ/mol for the β-relaxation and 96 kJ/mol for the αc-relaxation. The result that these activation energies did not depend on silica content may indicate the weak interaction between PVDF and silica. 相似文献
926.
927.
Okiko Miyata Kanami Muroya Tomoko Kobayashi Rina Yamanaka Seiko Kajisa Junko Koide Takeaki Naito 《ChemInform》2002,33(42):211-211
928.