The mechanical strength of oxide dispersion strengthened (ODS) ferritic steels depends on the dispersion and microstructural stability of the oxide particles. Yttria is normally selected as ...dispersion particles to strengthen ODS ferritic steels, and other additional elements such as titanium and aluminum are added to obtain finer dispersion particles for the improvement of the mechanical properties of the ODS steels. Kyoto University is involved with the development of new ODS ferritic steels. 16Cr–0.1Ti–0.35Y
2O
3 ODS steel is a fusion structural material. In this research, the irradiation resistance of 16Cr–0.1Ti–0.35Y
2O
3 (16Cr0.1Ti) ODS steel was investigated by high-resolution TEM and by performing an ion irradiation experiment. The ODS steel was consolidated by hot extrusion at 1150
°C and annealed at 1050
°C for 1
h for recrystallization. Oxides in 16Cr0.1Ti ODS steel were characterized by HRTEM and STEM-EDX and specified as (Y, Ti) complex oxides with an atomic ratio of Y:Ti
=
2:1. A 1.7
MeV tandem accelerator for heavy-ion irradiation at the dual-beam material irradiation facility for energy technology (DuET), Kyoto University, was used to introduce irradiation damages in materials. The comparison of the dispersion, shape, and chemical composition of the oxides between the pre- and post-irradiated materials revealed that (Y, Ti) complex oxides were stable under the ion irradiation up to 60
dpa at 650
°C.
Recent research results obtained in Europe, Japan, China and the USA on reduced activation ferritic/martensitic (RAFM) steels are reviewed. The present status of different RAFM steel products (plate, ...powder HIPped steel, many types of fusion and diffusion welds, unirradiated and irradiated states) is sufficient to present a strong case for the use of the steels in ITER test blanket modules. For application in DEMO, more research is needed, including the use of the International Fusion Materials Irradiation Facility (IFMIF) in order to quantify the effects of large amounts of transmutation products, such as helium and hydrogen.
Glaucoma is one of the leading causes of irreversible blindness that is characterized by progressive degeneration of optic nerves and retinal ganglion cells (RGCs). In the mammalian retina, ...excitatory amino-acid carrier 1 (EAAC1) is expressed in neural cells, including RGCs, and the loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP). Brimonidine (BMD) is an α2-adrenergic receptor agonist and it is commonly used in a form of eye drops to lower IOP in glaucoma patients. Recent studies have suggested that BMD has direct protective effects on RGCs involving IOP-independent mechanisms, but it is still controversial. In the present study, we examined the effects of BMD in EAAC1-deficient (KO) mice, an animal model of normal tension glaucoma. BMD caused a small decrease in IOP, but sequential in vivo retinal imaging and electrophysiological analysis revealed that treatment with BMD was highly effective for RGC protection in EAAC1 KO mice. BMD suppressed the phosphorylation of the N-methyl-D-aspartate receptor 2B (NR2B) subunit in RGCs in EAAC1 KO mice. Furthermore, in cultured Müller glia, BMD stimulated the production of several neurotrophic factors that enhance RGC survival. These results suggest that, in addition to lowering IOP, BMD prevents glaucomatous retinal degeneration by stimulating multiple pathways including glia-neuron interactions.
The comet assay has been widely used as a genotoxicity test for detecting primary DNA damage in individual cells. The micronucleus (MN) test is also a well-established assay for detecting ...clastogenicity and aneugenicity. A combination of the comet assay (COM) and MN test is capable of detecting a variety of genotoxic potentials as an in vitro screening system. Although the in vitro MN test has a robust protocol and Organisation for Economic Co-operation and Development (OECD) test guideline, the in vitro COM does not. To establish a robust protocol for the COM and to compare its sensitivity with that of the MN, we conducted COM and MN concurrently for five genotoxic agents (ethyl methanesulfonate, methyl methanesulfonate, hydrogen peroxide, gamma-rays and mitomycin C) and one non-genotoxic agent (triton X-100), using human lymphoblastoid TK6 cells. Relative cell count (RCC), relative population doubling (RPD), relative increase in cell count (RICC) and relative cell viability determined by trypan blue dye-exclusion assay (TBDE) were employed as cytotoxic measurements. However, the relative cell viability determined by TBDE just after the treatment was not an appropriate parameter of cytotoxicity for the genotoxic agents because it remained constant even at the highest doses, which showed severe cytotoxicity by RCC, RPD and RICC. The results of the COM showed qualitative agreement (positive or negative) with those of the MN except for mitomycin C, which is an interstrand cross-linker. The COM always required higher doses than the MN to detect the genotoxic potential of the genotoxic agents under the test conditions applied here. The doses that induced a comet tail always yielded <50% RICC, and do not accord to the OECD test guideline for MN because of their high cytotoxicity. These results are helpful for interpreting the results of the COM and MN in in vitro genotoxic hazard assessments. Further investigation is required to standardise the COM.
Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr–4.5Al–0.3Ti–2W–0.37 Y
2O
3 ODS ferritic steel have been examined using high-resolution transmission electron ...microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y
4Al
2O
9 (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (>20
nm) tend to be incoherent and have a spherical shape, whereas small particles (<10
nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe
8+
+
He
+) dual-beam irradiation are briefly addressed.
Two kinds of ODS high-Cr ferritic steels (commercial MA956 and an Al-free 16Cr-0.1Ti ODS ferritic steel) and one conventional ferritic/martensitic steel (T122) were irradiated at about 440 degreesC ...with high-energy super(20)Ne-ions in HIRFL. Successively increasing doses from 350 to 900 appm of Ne concentration, corresponding to atomic displacement levels from 0.7 to 1.8 dpa, were approached. A nearly uniform distribution of Ne concentration and atomic displacement damage was produced through the thickness of 60 mu m of the specimens by using an energy degrader. Mechanical properties of the specimens were tested with the small-ball punch technique. The test at room temperature shows a less significant ductility loss in the ODS ferritic steel MA956 than in the T122 irradiated to the same dose of 350 appm Ne/0.7 dpa. The test at 500 degreesC shows that the Al-free 16Cr-0.1Ti ODS ferritic steel does not exhibit observable loss of ductility even to the highest dose level (900 appm Ne/1.8dpa). An investigation with transmission electron microscopy (TEM) shows that voids with a diameter up to 70 nm were formed at grain boundaries in the conventional ferritic/martensitic steel T122 while only smaller bubbles were formed at the oxides/substrate interfaces in the ODS ferritic steel MA956. Mechanisms underlying the difference of irradiation response of the steels are discussed.
A planar scale grating with a pitch of 1
μm used in an interferential scanning-type planar encoder, which produces multi-axis position signals based on interference between first-order diffracted ...beams from the grating, is evaluated by a 100
mm-aperture Fizeau interferometer. The out-of-flatness of the grating is first evaluated from the wavefront of the zero-order diffracted beam from the grating. The grating is then tilted to align the axes of the first-order diffracted beams with that of the interferometer so that the
X- and
Y-directional pitch deviations of the grating can be evaluated from the wavefronts of the first-order diffracted beams.
Antimalarial activity of the terpene nerolidol Saito, Alexandre Y; Marin Rodriguez, Adriana A; Menchaca Vega, Danielle S ...
International journal of antimicrobial agents,
12/2016, Letnik:
48, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Highlights • Nerolidol had an antimalarial effect in a murine malaria model. • Nerolidol was non-toxic and non-genotoxic up to doses of 6.5 µM. • AUC0–12 values were 0.46 µM⋅h and 11.19 µM⋅h by ...inhalation and oral routes, respectively. • Parasitaemia was almost abolished by Day 15 of oral nerolidol treatment.
The phase and metal/oxide interface structure of the nanometer-scale particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel extruded at 1150
°C and 1050
°C were characterized ...by high-resolution transmission electron microscopy and diffraction contrast techniques, including weak beam electron microscopy. After extrusion at 1150
°C, yttrium–aluminum–hexagonal (YAH, YAlO
3) and yttrium–aluminum–perovskite (YAP, YAlO
3) oxides (diameter ⩽10
nm) constitute ∼55% and 38% of the particles, respectively; ∼78% of the particles (4.5–10
nm in diameter), which include 40% YAH oxide and 38% YAP phase with misfit (translational) moiré fringe spacing of 2.15
nm and 1.65
nm, respectively, are semi-coherent with the matrix. After extrusion at 1050
°C, almost all the particles are YAH phase, and ∼86.5% (diameter <4.5
nm) are coherent with the matrix. The coherency of the oxides is size dependent. The crystallographic orientation correlations of the oxides and matrix were found.
The surface of W(110) exhibits a Dirac-cone-like state with d character within a spin-orbit-induced symmetry gap. As a function of the wave vector parallel to the surface, it shows a nearly massless ...energy dispersion and a pronounced spin polarization, which is antisymmetric with respect to the Brillouin zone center. In addition, the observed constant energy contours are strongly anisotropic for all energies. This discovery opens new pathways to the study of surface spin-density waves arising from a strong Fermi surface nesting as well as d-electron-based topological properties.
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