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Herein, the evolution of the microstructure of a newly developed oxide dispersion strengthened (ODS) Ni‐based superalloy with emphasis on γ′ morphology during different processing conditions is investigated. X‐ray analysis of severely deformed mechanically alloyed (MAed) powders shows that the as‐milled nano‐sized crystallite size increases with annealing associated with the sharp drop of dislocation density. At the same time, by annealing MAed powders γ′ precipitates above 300 °C, and depending on the aging treatment regime, Vickers microhardness changes mainly due to γ′ distribution and dislocation release. The thorough evaluation of γ′ morphology in the microscale shows that in contrast to the spherical shape of γ′, after heat treatment of solutionized MAed ODS superalloy, irregular‐shaped γ′ exist in the MAed ODS superalloy due to severe plastic deformation during mechanical alloying. However, a unique nanostructured lamellar morphology forms in the γ′ precipitates with different lamellae directions. This structure is stable in all subsequent processing steps with γ′ lamellae of (011¯) planes and intervals of 20–30 nm. The scanning transmission electron microscopy (STEM)–high‐angle annular dark‐field (HAADF) composition analysis clarifies that the nanostructured lamellar morphology shows no partitioning of alloying elements, and its origin may be attributed to the formation of antiphase domain boundaries. [ABSTRACT FROM AUTHOR]

Aim: This is a cross-sectional study of relation between metabolic syndrome and cognitive function in community-dwelling non-demented older adults in Japan. We examine the effect of metabolic syndrome and its components on global cognitive function. We also aim to clarify differences of specific cognitive domains between the subjects with and without metabolic syndrome. Methods: We studied 2150 subjects aged between 60 and 90 years whose scores on mini mental state examination (MMSE) were over 23 points. We analyzed difference in MMSE scores between the subjects with and without metabolic syndrome. Logistic regression analysis was performed with MMSE score as the dependent variable and metabolic syndrome components as the independent variable adjusted with age. We also examined differences in attention, logical memory, and verbal and category fluency between the subjects with and without metabolic syndrome. Results: MMSE scores were not significantly different between subjects with and without metabolic syndrome. In logistic regression analysis, the score of MMSE was significantly negatively associated with triglycerides in males and significantly negatively associated with abdominal circumference in females. Subjects with metabolic syndrome showed significantly lower performance of attention tasks compared to subjects without metabolic syndrome. Conclusions: Our results suggest that in community-dwelling non-demented Japanese older adults, attention but not global cognitive function may be impaired by metabolic syndrome. Inverted association between some components of metabolic syndrome and global cognitive function indicate necessity of further studies on the relation between undernutrition and cognitive function. [ABSTRACT FROM AUTHOR]

The reactive elements (Ti, Al and Zr) have been widely used for the improvement of the strength or the oxide resistance of ODS steels. In the present work, we studied the effect of the reactive elements on the precipitation of oxide particles, especially focusing upon the appropriate amount of the oxide composing elements, by addition of the large amounts of Y2O3 and reactive elements. The mechanically alloyed powders are annealed in a wide temperature range from 773 to 1423 K and then analysed by various analysis methods (small-angle X-ray scattering and X-ray diffraction by synchrotron radiation X-ray, scanning transmission electron microscope combined with energy dispersion X-ray spectroscopy, high-resolution transmission microscopy and 3D-atom probe). Ti, Al and Zr enhanced the growth of oxide particles, opposite to the many studies of Ti- and Zr-added ODS steels, as a result of the addition of Y2O3 and these elements ten times larger than those for usual use. The nucleation and growth of oxide particles are discussed by simulating the critical radius of nucleation and the growth based on the LSW theory. Y4Zr3O12 is stable and easy to precipitate even at lower annealing temperature. All reactive elements enhance the growth of oxide particles because of their big molar volume as compared to that of Y2O3. [ABSTRACT FROM AUTHOR]

9CrODS steel, a candidate fission and fusion structural material, was subjected to hot-rolling with varying parameters of surface temperature and cooling rate just after hot-rolling. The deformation-induced dynamic ferrite transformation was confirmed at the rolling temperature 805 °C above Ar3 (780 °C). This transformation exhibits three characteristic features: transformation for extremely short duration (0.044 second), retaining carbon content equal to the original without long-distance carbon diffusion, and elongated coarse ferrite grains (10 μm). The massive transformation was proposed for the dynamic ferrite transformation from the hot-rolled austenite. The driving force for massive transformation was quantitatively estimated considering dislocations accumulated by hot-rolling. It was also shown that the oxide particles in 9CrODS steel play a critical role for dynamic ferrite transformation by suppressing the dynamic recrystallization at hot-rolling. [ABSTRACT FROM AUTHOR]

The interaction between oxide particles and dislocations in a 9Cr-ODS ferritic steel is investigated by both static andin situTEM observation under dynamic straining conditions and room temperature. The measured obstacle strength () of the oxide particles was no greater than 0.80 and the average was 0.63. The dislocation loops around some coarsened particles were also observed. The calculated obstacle strength by a stress formula of the Orowan interaction is nearly equaled to the average experimental value. Not only cross-slip system but also the Orowan interaction should be considered as the main interaction mechanism between oxide particles and dislocation in 9CrODS ferritic steel. [ABSTRACT FROM AUTHOR]

We report the current status of the development of our new detectors for far-infrared (FIR) astronomy. We develop Blocked-Impurity-Band (BIB)-type Ge detectors to realize large-format compact arrays covering a wide FIR wavelength range up to 200 $$\upmu $$ m. We fabricated Ge junction devices of different physical parameters with a BIB-type structure, using the room temperature, surface-activated wafer bonding (SAB) method. We measured the absolute responsivity and the spectral response curve of each device at low temperatures, using an internal blackbody source in a cryostat and a Fourier transform spectrometer, respectively. The results show that the SAB Ge junction devices have significantly higher absolute responsivities and longer cut-off wavelengths of the spectral response than the conventional bulk Ge:Ga device. Based upon the results, we discuss the optimum parameters of SAB Ge junction devices for FIR detectors. We conclude that SAB Ge junction devices possess a promising applicability to next-generation FIR detectors covering wavelengths up to $$\sim $$ 200 $$\upmu $$ m with high responsivity. As a next step, we plan to fabricate a BIB-type Ge array device in combination with a low-power cryogenic readout integrated circuit. [ABSTRACT FROM AUTHOR]

We are developing far-infrared (FIR) imaging sensors for low-background and high-sensitivity applications such as infrared astronomy. Previous FIR monolithic imaging sensors, such as an extrinsic germanium photo-conductor (Ge PC) with a PMOS readout integrated circuit (ROIC) hybridized by indium pixel-to-pixel interconnection, had three difficulties: (1) short cut-off wavelength (120 $$\upmu $$ m), (2) large power consumption (10 $$\upmu $$ W/pixel), and (3) large mismatch in thermal expansion between the Ge PC and the Si ROIC. In order to overcome these difficulties, we developed (1) a blocked impurity band detector fabricated by a surface- activated bond technology, whose cut-off wavelength is longer than 160 $$\upmu $$ m, (2) a fully-depleted silicon-on-insulator CMOS ROIC which works below 4 K with 1 $$\upmu $$ W/pixel operating power, and (3) a new concept, Si-supported Ge detector, which shows tolerance to thermal cycling down to 3 K. With these new techniques, we are now developing a $$32 \times 32 $$ FIR imaging sensor. [ABSTRACT FROM AUTHOR]

In spent fuel nuclear reprocessing plant, nitric acid is the main medium used in PUREX method. The passive film compositions and corrosion resistance of 11 % Cr ferritic/martensitic and 9-15 % Cr oxide dispersion strengthened steels in different nitric acid concentrations were studied. The open circuit potential is shifted toward more noble potential as the concentrations increased from 1 M HNO to 9 M HNO in all the investigated alloy steels. The results of the potentiodynamic polarization plots also exhibited a shift in corrosion potential as the concentrations increased from 1 M to 9 M HNO This shift is undesirable because of risk of overshooting the potential beyond passive region and may result into transpassive corrosion. The X-ray photoelectron spectroscopy results of the passive film analysis are composed mostly of FeO, CrO, and YO, and the depth profile of Fe and Cr concentrations vary depending upon the nitric acid concentration. The surface morphology after the corrosion test does not show intergranular corrosion attack at the nitric acid concentrations studied. It is desirable that materials for use in nitric acid service are resistant to such corrosion induced degradation. [ABSTRACT FROM AUTHOR]

Brain vasculature forms the blood-brain barrier ( BBB) that restricts the movement of molecules between the brain and blood, but the capillary of the median eminence ( ME) lacks the BBB for secretion of adenohypophysial hormone-releasing peptides. In the present study, we aimed to elucidate whether continuous angiogenesis occurs in the ME of adult mice. By using a mitotic marker, bromodeoxyuridine ( Br dU), we demonstrated that new endothelial cells were born continuously in the ME of adults. Prominent expression of NG2, platelet-derived growth factor receptor B ( PDGFRB), and delta-like ligand 4 was observed at pericytes of adults, although the expression of these angiogenesis-associated proteins has been shown to be at low or trace levels in adult mature capillary. In addition, vascular endothelial growth factor ( VEGF), a key regulator of angiogenesis, was expressed highly in the nervous parenchyma of the ME. Expression of VEGF receptor 2 ( VEGFR2) was observed at endothelial cells in the external zone and at somatodendrites in the internal zone. Finally, a VEGFR- and PDGFR-associated tyrosine kinase inhibitor, SU11248, significantly decreased the number of Br dU-positive proliferating endothelial cells and parenchyma cells. In conclusion, the present study demonstrates VEGF-dependent continuous angiogenesis in the ME of adult mouse brains under normal conditions, which provides new insight into our understanding of neurosecretion in the ME. [ABSTRACT FROM AUTHOR]

The high-temperature oxidation behavior of pure Ni in air and Ar with and without 30 vol%HO at 1,000 °C was investigated to understand the effects of water-vapor on the resulting oxidation kinetics and scale structures. It was found that water-vapor significantly affected the morphology and scale structure of NiO. A duplex NiO scale with a powder-like outer and dense inner NiO layer developed when the Ni was oxidized in atmospheres containing water-vapor. The grain size of the dense inner NiO layer was much smaller than that formed in dry atmospheres. The growth of the powder-like NiO required outward diffusion of Ni and its continued formation occurred at the interface between the powder and dense NiO layers. The dense inner NiO layer grew outward and incorporated the powder-like NiO particles and the resulting grain size of the inner layer was smaller in the presence of water-vapor. The water-vapor is speculated to have prevented sintering of NiO particles during growth of the NiO scale. [ABSTRACT FROM AUTHOR]

The single- and multi-mode Richtmyer-Meshkov instabilities (RMI) with reshock are numerically analyzed in two- and three-dimensional domains. Four different types of air/ SF interface shapes are investigated in a shock tube configuration, and the predicted post-reshock growth rates are compared with available empirical models of Mikaelian's (Physica D 36(3):343-347, ) and Charakhch'an's (J Appl Mech Tech Phys 41(1):23-31, ). The simulation of 3D multi-mode RMI shows good agreement with a past experimental study, but other interface types (2D single-mode, 2D multi-mode and 3D single-mode) result in different growth rates after reshock. Parametric studies are therefore performed to investigate the sensitivities of the post-reshock growth rates to model the empirical parameters. For single-mode RMI configurations, the interface shape is found to be only a weak function of the post-reshock growth rate, as also predicted by previous reshock models. The post-reshock growth rate shows a linear correlation to the velocity jump due to reshock; however, it is only about a half of the prediction of Charakhch'an's model even though the growth before reshock compares well with pre-reshock models. The 3D single-mode post-reshock RMI growth rate is nearly 1.6 times larger than the 2D single-mode RMI. The parametric studies of multi-mode RMI show two distinctly different growth rates depending on the mixing conditions at reshock. If the interface remains sharp at the time of reshock, the post-reshock growth rate is as large as the single-mode cases. However, if the interface is mixed due to non-linear interactions of bubbles and spikes, the growth rates becomes slow and independent of the interface shapes. Overall, this study provides new insights into the flow features of reshocked RMI for different initial perturbation types. [ABSTRACT FROM AUTHOR]

This is a continuation of our series of works for the inhomogeneous Boltzmann equation. We study qualitative properties of classical solutions; the full regularization in all variables, uniqueness, non-negativity and convergence rate to the equilibrium, to be precise. Together with the results of Parts I and II about the well-posedness of the Cauchy problem around the Maxwellian, we conclude this series with a satisfactory mathematical theory for the Boltzmann equation without angular cutoff. [ABSTRACT FROM AUTHOR]

We prove the global existence and uniqueness of classical solutions around an equilibrium to the Boltzmann equation without angular cutoff in some Sobolev spaces. In addition, the solutions thus obtained are shown to be non-negative and C in all variables for any positive time. In this paper, we study the Maxwellian molecule type collision operator with mild singularity. One of the key observations is the introduction of a new important norm related to the singular behavior of the cross section in the collision operator. This norm captures the essential properties of the singularity and yields precisely the dissipation of the linearized collision operator through the celebrated H-theorem. [ABSTRACT FROM AUTHOR]

As a continuation of our series works on the Boltzmann equation without angular cutoff assumption, in this part, the global existence of solution to the Cauchy problem in the whole space is proved in some suitable weighted Sobolev spaces for hard potential when the solution is a small perturbation of a global equilibrium. [ABSTRACT FROM AUTHOR]

This paper is about the propagation of the singularities in the solutions to the Cauchy problem of the spatially inhomogeneous Boltzmann equation with angular cutoff assumption. It is motivated by the work of Boudin–Desvillettes on the propagation of singularities in solutions near vacuum. It shows that for the solution near a global Maxwellian, singularities in the initial data propagate like the free transportation. Precisely, the solution is the sum of two parts in which one keeps the singularities of the initial data and the other one is regular with locally bounded derivatives of fractional order in some Sobolev space. In addition, the dependence of the regularity on the cross-section is also given. [ABSTRACT FROM AUTHOR]

We consider a body moving along the x-axis under the action of an external force E and immersed in an infinitely extended perfect gas. We assume the gas to be described by the mean-field approximation and interacting elastically with the body. In this setup, we discuss the following statement: "Let V0 be the initial velocity of the body and V∞ its asymptotic velocity, then for |V0 - V∞| small enough it results |V(t) - V∞| ≈ C t-d-2 for t large, where V(t) is the velocity of the body at time t, d the dimension of the space and C is a positive constant depending on the medium and on the shape of the body". The reason for the power law approach to the stationary state instead of the exponential one (usually assumed in viscous friction problems), is due to the long memory of the dynamical system. In a recent paper by Caprino, Marchioro and Pulvirenti,3 the case of E constant and positive, with 0 < V0 < V∞, for a disk orthogonal to the x-axis has been discussed. Here we complete the analysis in the cases E > 0 with V0 > V∞ and E = 0. We also approach the problem of an x-dependent external force, by choosing E of harmonic type. In this case we obtain the power-like asymptotic time behavior for the body position X(t). The investigation is done in detail for a disk orthogonal to the x-axis and then, by a sketched proof, extended to a body with a general convex shape. [ABSTRACT FROM AUTHOR]

Based on the global existence theory of the Vlasov–Poisson–Boltzmann system around vacuum in the N-dimensional phase space, in this paper, we prove the uniform L1 stability of classical solutions for small initial data when N ≥ 4. In particular, we show that the stability can be established directly for the soft potentials, while for the hard potentials and hard sphere model it is obtained through the construction of some nonlinear functionals. These functionals thus generalize those constructed by Ha for the case without force to capture the effect of the force term on the time evolution of solutions. In addition, the local-in-time L1 stability is also obtained for the case of N = 3. [ABSTRACT FROM AUTHOR]

Wavelet-crosscorrelation analysis is a new application of wavelet analysis used to show the propagation of epileptiform discharges and to localize the corresponding lesions. We have shown previously that this analysis can help predict brain conditions statistically (Mizuno-Matsumoto et al. 2002). Our objective was to assess whether wavelet-crosscorrelation analysis reveals the initiation and propagation of epileptiform activity in human patients. The data obtained from three patients with simple partial seizures (SPS) using whole-head magnetoencephalography (MEG) were analyzed by the wavelet-crosscorrelation method. Wavelet-crosscorrelation coefficients (WCC), the coherent structure of each possible pair of signals from 64 MEG channels for various periods, and the time lag (TL) in two related signals, were ascertained. We clearly demonstrated both localization of the irritative zone and propagation of the epileptiform discharges. Wavelet-crosscorrelation analysis can help reveal and visualize the dynamic changes of brain conditions. The method of this analysis can compensate for other existing methods for the analysis of MEG, electroencephalography (EEG) or Elecotrocorticography (ECoG). Our proposed method suggests that revealing and visualizing the dynamic changes of brain conditions can help clinicians and even patients themselves better understand such conditions. [ABSTRACT FROM AUTHOR]

Oxide-dispersion-strengthened (ODS) ferritic steel incorporating nanoscale oxide particles was produced by mechanical alloying, and the complex oxide particles, comprised of titanium and yttrium, characterized by high-resolution transmission electron microscopy (HRTEM) and characteristic X-ray nanoanalyses. The interface between the ferritic matrix and the major Ti-Y complex oxide was incoherent. From HRTEM and characteristic X-ray nano-analyses, plus the extremely limited literature data on ODS ferritic steels, it was determined that the most stable complex oxide was cubic Y2Ti2O7. which formed by a spontaneous reaction between nano-sized ceramics with a low solubility limit in the metal. [ABSTRACT FROM AUTHOR]

We prove that a free boundary problem for an incompressible Euler equation with surface tension is uniquely solvable, locally in time, in a class of functions of finite smoothness. Moreover, it is shown that the solution of this problem converges to the solution of the problem without surface tension as the coefficient of the surface tension tends to zero. [ABSTRACT FROM AUTHOR]

In this paper we study the two-phase Stefan problem for a viscous incompressible fluid which is a model of melting a solid to a liquid or of soldificating a liquid to a solid with a liquid flowing. The unique solvability is established in Hölder spaces locally in time. The method of the proof is rather standard, however the result obtained is completely new: the existence in the Hölder spaces with the same Hölder exponents as the data and the uniqueness also in the same Hölder spaces. [ABSTRACT FROM AUTHOR]

We present a simple example of the infinite-dimensional map which has a scrambled set. It is the “logistic map with diffusion” which is a natural extension of the well known one-dimensional logistic map and derived by a semi-implicit discretization in t of a semilinear parabolic equation obtained by adding the diffusion term to the logistic equation. This map is neither expansive nor invertible even locally and hence outside of existing theories of scrambled and hyperbolic invariant sets. We will establish a sufficient condition for it to become a contractive perturbation of the logistic map and construct a scrambled set with several modifications of the method developed in Refs. 7 and 8. [ABSTRACT FROM AUTHOR]

An understanding of the effects of long-term, low-dose-rate radiation on core components is critical to light-water reactor plant life extension. Following reactor shutdown, materials that had experienced long exposures to low-dose-rate irradiation were retrieved from the EBR-II research reactor for analysis. These components are being analyzed to provide insight into pressurized water reactor life extension. In this work, three examples of EBR-II materials analyses are highlighted: radiation-induced segregation in 304 stainless steel, stress relaxation in Inconel X750, and swelling in 316 stainless steel. [ABSTRACT FROM AUTHOR]

We consider the problem of blow-up of smooth solutions for the 3-D Boussinesq equations. Owing to the viscosity, we prove that the maximum norm of the gradient of vorticity controls the breakdown of the solutions; the scalar temperature function is shown to be irrelevant to the breakdown. [ABSTRACT FROM AUTHOR]

Considerable attention has been paid to the research of the electron tomography due to determine the three-dimensional (3D) structure of materials [1]. One of the electron tomography techniques, focused ion beam/scanning electron microscopy (FIB-SEM) imaging has advantages of high resolutions (10 nm), large area observation (μm order) and simultaneous energy dispersive x- ray microanalysis (EDS)/ electron backscatter diffraction (EBSD) analysis. The purpose of this study, three-dimensional EBSD analysis of ODS ferritic steel which carried out cold work using FIB-SEM equipment was conducted, and it aimed at analyzing the microstructure obtained there. The zone annealing tests were conducted for ferritic steel [2,3], whichwere produced through mechanical alloying and hot-extrusion. After zone annealing, specimens were mechanically polished with #400∼4000 emery paper, 1 µm diamond paste and alumina colloidal silica. The serial sectioning and the 3D-electron backscattering diffraction (3D-EBSD) analysis were carried out. We made the micro pillar (30 x 30 x 15 µm). The EBSD measurements were carried out in each layer after serial sectioning at a step size and milling depth was 80 nm with 30 slices. After EBSD analysis, the series of cross-sectional images were aligned according to arbitrarily specified areas and then stacked up to form a volume. Consequently, we obtained the 3D-IPF maps for ODS ferritic steel. In this specimen, the {111} and {001} grains are layered by turns. In addition, the volume fraction value of both plane are similar. The aspect ratio increases with specimen depth. The 3D-EBSD mapping is useful to analysis of the bulk material since this method obtain many microstructure information, such a shape, volume and orientation of the crystal, grain boundary. [ABSTRACT FROM PUBLISHER]