[en] In recent developments in nuclear fusion research, certain design concepts for liquid breeder blankets for nuclear fusion reactors use molten salts, such as FLiBe, as coolant material. The mean velocity of liquid coolant material in a reactor is strongly influenced by magnetic field, and hence it is important to study the turbulent magnetohydrodynamic (MHD) flow behavior for an applied magnetic field perpendicular to the main flow. Furthermore, because the flow characteristics of coolant at high Reynolds number are assumed to be different from the usual turbulent MHD flow, it is important to investigate the flow under a magnetic field where the Reynolds number is high. A direct numerical simulation (DNS) of turbulent heat transfer with high Reynolds number has been carried out to show the effects of magnetic field. In this study, the Reynolds number for channel flow based on bulk velocity, viscosity, and channel width was set to be constant; Re_b=45818. A uniform magnetic field was applied in the direction of the wall normal. The values of Hartmann number Ha were 32.5 and 65. A constant temperature was applied to the wall as a thermal boundary condition. Prandtl number of the working fluid was assumed to be 0.06. The number of computational grids used in this study was 1024 x 1024 x 768 in the x-, y- and z- directions, respectively. The turbulent quantities such as the mean flow, mean temperature, turbulent stress, and turbulent statistics were obtained by DNS. Moreover, the large-scale turbulent structure about temperature field will be presented at final paper. (orig.)

[en] Chronic kidney disease (CKD) is an important risk factor for cardiovascular disease in patients with diabetes. The relationship between renal manifestations of CKD (albuminuria and decreased glomerular filtration rate) and silent cerebral infarction (SCI) has attracted attention; however, most studies examined the effects of components of CKD on prevalence of SCI. We sought to assess the relationship between SCI and the development and progression of nephropathy in type 2 diabetic patients. We studied 366 type 2 diabetic patients with normoalbuminuria (urinary albumin-to-creatinine ratio [ACR] <30 mg g^-1, N=246) or microalbuminuria (ACR=30-299 mg g^-1, N=120). SCI was defined by cranial MRI. The primary end point was progression from normo- to microalbuminuria or from micro- to macroalbuminuria. The cumulative incidence of the primary end point was estimated using the Kaplan-Meier method. Risk estimates for reaching the end point were calculated using Cox proportional hazard model analyses. During a median follow-up period of 3.9 years, 23 normoalbuminuric and 24 microalbuminuric patients reached the primary end point. Patients with SCI (N=171) had a greater incidence of reaching the end point than those without SCI (N=195, P=0.020 by the log-rank test), with a hazard ratio of 2.02 (95% confidence interval=1.09-3.72, P=0.025) in the multivariate Cox regression model. Although the common pathogenesis of SCI and albuminuria in diabetic patients is still unclear, SCI may be a predictor of progression of nephropathy in type 2 diabetic patients. (author)

[en] Based on the studies of electrochemical stability of precipitates in 9Cr-1Mo steels, a method for selective separation and state analysis of Laves phase was established. By use of this method, precipitation behavior of Laves phase and carbides was examined and the effect of Laves phase on the mechanical properties of this steel after long-time aging was studied. The results are summerized as follows. (1) Laves phase extracted from 9Cr-1Mo steel was electrochemically less stable than carbides (M₂₃C₆), and was selectively decomposed and separated from carbides by controlled-potential electrolysis at +0.8 V vs. SCE in 10%acetylacetone-5%LiCl-methanol (secondary electrolysis). (2) The amount of Laves phase can be calculated from the total dissolved amount of Fe, Cr, Mo and Si after the secondary electrolysis. The amount of carbides (M as M₂₃C₆) can be analyzed from the total amount of Fe, Cr, and Mo in insoluble residues after the secondary electrolysis. (3) In the steels aged for 1000 h, Laves phase was found at temperatures between 550 and 625degC, the amount was maximum at 600degC, and increased with aging. (4) Precipitation of Laves phase decreased the Charpy absorbed energy of 9Cr-1Mo steel; when precipitated 0.5 mass% of Laves phase, about 120 J of Charpy absorbed energy decreased. (author)

[en] A low Pr number fluid flow, such as liquid-metals, has relatively less than turbulent heat transport capability because of the liquid-metals' high thermal conductivity and its very large thermal boundary layer. Liquid-metals as coolant material in fusion reactor have a significant role in the design of advanced reactors. This is true since the investigation of thermal behavior in the actual facility environment such as in the case of low Pr number fluid flow, is needed at high Reynolds number under a magnetic field. In the present study, a direct numerical simulation (DNS) for the low Pr number fluid flow of turbulent heat transfer with high Reynolds number has been carried out to show the effects of magnetic field. The Reynolds number for channel flow based on bulk velocity U_b, viscosity ν, and channel width 2δ was set to be constant as Re_b = 2δU_b/ν = 45,818. A uniform magnetic field was applied in a direction perpendicular to the wall of the channel. The values of Hartmann number Ha were 0 and 65 (where Ha=2δB₀√(σ/ρν)), and Prandtl number was 0.06. The turbulent quantities such as the mean temperature, turbulent heat flux, and temperature variant were obtained by DNS. Although large-scale turbulent structures of both velocity and temperature fields are found at the central region of the channel, the mean temperature profiles near wall region show up as laminar profile, that is, the thermal efficiency of the transport is less than that of turbulent flow. This means that it is necessary to consider the fusion reactor design of thermal mixing argumentation for low Pr number fluid flow because the heat transfer enhancement at turbulent flow cannot be acceptable even where the flow state happens to be a turbulent flow at high Reynolds number