http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Hiroaki Wakayama,Hirotaka Yonekura 한국고분자학회 2017 Macromolecular Research Vol.25 No.3
Structural control of polymer nanocomposites is important for their applications in organic semiconductors, lithographic nanopatterning, separation membranes, and nanofabrication templates. However, manufacturing nanocomposite materials with novel structures in a highly efficient yet precise manner remains a great challenge. To create nanocomposite structures, we combined self-assembly processing of block copolymer (BCP)-metal complex nanocomposites with an applied magnetic field. Here, we describe in detail the mechanism of magnetic alignment of block copolymers doped with metal complexes; specifically, we investigated the effect of the applied magnetic field on the phase behavior of the assembled block copolymer-metal complex nanocomposites with various molecular weights and with different molecular structures. We show that our combination of self-assembly processing and application of a magnetic field yielded lamellar structures of alternating multilayers with different layer thicknesses. This self-assembled structure is not included in phase diagrams of BCPs. The influence of the block copolymers’ molecular structures on the nanocomposites’ phase transformation behavior is also discussed. Our results provide a route to manufacturing nanocomposite materials in a highly efficient yet precise manner, which could lead to improvement in the material properties of nanocomposites.
Bui, Hong-Thuy,Wakayama, Sayaka,Kishigami, Satoshi,Park, Keun-Kyu,Kim, Jin-Hoi,Thuan, Nguyen Van,Wakayama, Teruhiko Society for the Study of Reproduction [etc.] 2010 BIOLOGY OF REPRODUCTION Vol.83 No.3
<P>Our group and others have found that the treatment of embryos with trichostatin A (TSA) after cloning by somatic cell nuclear transfer (SCNT) results in a significant improvement in efficiency. We believe that TSA treatment improves nuclear remodeling via histone modifications, which are important in the epigenetic regulation of gene silencing and expression. Some studies found that treatment of SCNT-generated embryos with TSA improved lysine acetylation of core histones in a manner similar to that seen in normally fertilized embryos. However, how histone methylation is modified in TSA-treated cloned embryos is not completely understood. In the present study, we found that TSA treatment caused an increase in chromosome decondensation and nuclear volume in SCNT-generated embryos similar to that in embryos produced by intracytoplasmic sperm injection. Histone acetylation increased in parallel with chromosome decondensation. This was associated with a more effective formation of DNA replication complexes in treated embryos. We also found a differential effect of TSA on the methylation of histone H3 at positions K4 and K9 in SCNT-generated embryos that could contribute to genomic reprogramming of the somatic cell nuclei. In addition, using 5-bromouridine 5'-triphosphate-labeled RNA, we showed that TSA enhanced the levels of newly synthesized RNA in 2-cell embryos. Interestingly, the amount of SCNT-generated embryos showing asymmetric expression of nascent RNA was reduced significantly in the TSA-treated group compared with the nontreated group at the 2-cell stage. We conclude that the incomplete and inaccurate genomic reprogramming of SCNT-generated embryos was improved by TSA treatment. This could enhance the reprogramming of somatic nuclei in terms of chromatin remodeling, histone modifications, DNA replication, and transcriptional activity.</P>
Van Thuan, Nguyen,Bui, Hong-Thuy,Kim, Jin-Hoi,Hikichi, Takafusa,Wakayama, Sayaka,Kishigami, Satoshi,Mizutani, Eiji,Wakayama, Teruhiko Journals of Reproduction and Fertility 2009 Reproduction Vol.138 No.2
<P>Since the birth of Cumulina, the first mouse clone produced by somatic cell nuclear transfer (SCNT), the success rate of cloning in mice has been extremely low compared with other species and most of the inbred mouse strains have never been cloned. Recently, our laboratory has found that treatment of SCNT mouse embryos with trichostatin A, a histone deacetylase inhibitor (HDACi), improved the full-term development of B6D2F1 mouse clones significantly. However, this was not effective for the inbred strains. Here, we show for the first time that by treating SCNT embryos with another HDACi, scriptaid, all the important inbred mouse strains can be cloned, such as C57BL/6, C3H/He, DBA/2, and 129/Sv. Moreover, the success of somatic nuclear reprogramming and cloning efficiency via nuclear transfer technique is clearly linked to the competent de novo synthesis of nascent mRNA in cloned mouse embryos.</P>
Hayashi, Toshimitsu,Wakayama, Shuichi The Korean Society for Composite Materials 2009 Advanced composite materials Vol.18 No.1
The effect of porous matrix on thermal fatigue behavior of 3D-orthogonally woven SiC/SiC composite was evaluated in comparison with that having relatively dense matrix. The porous matrix yields open air passages through its thickness which can be utilized for transpiration cooling. On the other hand, the latter matrix is so dense that the air passages are sealed. A quantity of the matrix was varied by changing the number of repetition cycles of the polymer impregnation pyrolysis (PIP). Strength degradation of composites under thermal cycling conditions was evaluated by the $1200^{\circ}C$/RT thermal cycles with a combination of burner heating and air cooling for 200 cycles. It was found that the SiC/SiC composite with the porous matrix revealed little degradation in strength during the thermal cycles, while the other sample showed a 25% decrease in strength. Finally it was demonstrated that the porous structure in 3D-SiC/SiC composite improved the thermal fatigue durability.