タングステン単結晶におけるイオン照射硬化および微細組織発達の方位依存性

京都大学0048新制・課程博士博士(エネルギー科学)甲第20484号エネ博第353号新制||エネ||70(附属図書館)京都大学大学院エネルギー科学研究科エネルギー変換科学専攻(主査)教授 木村 晃彦, 教授 星出 敏彦, 教授 今谷 勝次学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Evaluation of helium effect on ion-irradiation hardening in pure tungsten by nano-indentation method

As-received and recrystallized pure tungsten (W) were irradiated with 6.4MeV Fe3+ up to 2dpa with or without He+ at 300°C, 500°C, 700°C and 1000°C respectively. Irradiation hardening was measured by the nano-indentation method. An equation to evaluate the bulk equivalent hardness was derived on the assumption that the geometrically necessary dislocation (GND) densities at an indentation depth were the same before and after irradiation. Ion-irradiation always induces hardening in both as-received and recrystallized W at all the experiment temperatures. In the case of single-beam irradiation, the recrystallized W exhibited higher hardening than as-received one. The effect of helium on the irradiation hardening is dependent on the material condition: as-received W showed an additional hardening by helium at all the irradiation temperatures, while in recrystallized W the hardening was not affected by helium below 700°C

Molecular Pharmacology / Functional Selectivity and Partial Efficacy at the Monoamine Transporters: A Unified Model of Allosteric Modulation and Amphetamine-Induced Substrate Release

All clinically approved drugs targeting the plasmalemmal transporters for dopamine, norepinephrine, and serotonin act either as competitive uptake inhibitors or as amphetamine-like releasers. Monoamine transporter (MAT) ligands that allosterically affect MAT-mediated substrate uptake, release, or both were recently discovered. Their modes of action have not yet been explained in a unified framework. Here, we go beyond competitive inhibitors and classic amphetamines and introduce concepts for partial efficacy at and allosteric modulation of MATs. After we elaborate on a kinetic account for amphetamine action, we provide an explanation for partial release (i.e., the observation that some amphetamines are less efficacious than others in inducing monoamine efflux). We then elucidate mechanisms of allosteric inhibition and stimulation of MATs, which can be functionally selective for either substrate uptake or amphetamine-induced release. These concepts are integrated into a parsimonious kinetic framework, which relies exclusively on physiologic transport modes (without any deviation from an alternating access mechanism). The model posits cooperative substrate and Na binding and functional selectivity by conformational selection (i.e., preference of the allosteric modulators for the substrate-loaded or substrate-free states of the transporter). Thus, current knowledge about the kinetics of monoamine transport is sufficiently detailed to provide a quantitative description of the releasing action of amphetamines, of substrate uptake, and of selective modulation thereof by allosteric modulators.(VLID)489184