Satoru Ishihara

Hot pressing of Fe-Co-Nd-Dy-B glassy powders in supercooled liquid state and hard magnetic properties of the consolidated alloys

Fe67Co9.5Nd3Dy0.5B20 glassy powders have been consolidated by uniaxial hot pressing in the supercooled liquid state. The compact obtained by hot pressing at 833 K has high relative densities of over 99.0% and keeps a glassy single phase. The bulk compact exhibits good hard magnetic properties after annealing for 600 s at 913 K.

Identification of Dynamin-2-mediated Endocytosis as a New Target of Osteoporosis Drugs, Bisphosphonates

Nitrogen-containing bisphosphonates are pyrophosphate analogs that have long been the preferred prescription for treating osteoporosis. Although these drugs are considered inhibitors of prenylation and are believed to exert their effects on bone resorption by disrupting the signaling pathways downstream of prenylated small GTPases, this explanation seems to be insufficient. Because other classes of prenylation inhibitors have recently emerged as potential antiviral therapeutic agents, we first investigated here the effects of bisphosphonates on simian virus 40 and adenovirus infections and, to our surprise, found that viral infections are suppressed by bisphosphonates through a prenylation-independent pathway. By in-house affinity-capture techniques, dynamin-2 was identified as a new molecular target of bisphosphonates. We present evidence that certain bisphosphonates block endocytosis of adenovirus and a model substrate by inhibiting GTPase activity of dynamin-2. Hence, this study has uncovered a previously unknown mechanism of action of bisphosphonates and offers potential novel use for these drugs.

Bulk consolidation of non-oxide ceramic powders derived from polymer precursors

Consolidation of pyrolyzed powders has been tried by hot isostatic pressing (HIP) without sintering additives, in order to obtain dense non-oxide ceramic bulk materials derived from polymer precursors. Si1.0C1.6N1.3 ceramic powders were derived from a polyvinylsilazane polymer. The polymer was thermally crosslinked at 250oC and pyrolyzed at 1050oC under Ar atmosphere. The pyrolyzed powders were die-pressed into rectangular bars at room temperature and densified by HIP at 1400oC-900 MPa and 1500oC-950 MPa. Dense ceramic monolith, in which pores were not observed by optical microscopy, was obtained by the HIP consolidation at 1500oC-950 MPa. The microstructure of the ceramic monolith was a nano-composite structure consisted of α-Si3N4 and graphite phases. In the compression tests of the HIP-treated sample, slight plastic deformation was observed at 1400 and 1500oC in spite of high compressive stress over 1000 MPa. On the other hand, the sample showed a compressive strain of about 7% at 1000 MPa at 1600oC. The compressive strain of about 11% was achieved at 1700oC.