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41.
Effect of Ultrasonication on the Microstructure and Tensile Elongation of Zirconia-Dispersed Alumina Ceramics Prepared by Colloidal Processing 总被引:1,自引:0,他引:1
Tohru S. Suzuki Yoshio Sakka Keishi Nakano Keijiro Hiraga 《Journal of the American Ceramic Society》2001,84(9):2132-2134
To obtain dense, fine-grained ceramics, fine particles and advanced powder processing, such as colloidal processing, are needed. Al2 O3 and ZrO2 particles are dispersed in colloidal suspensions by electrosteric repulsion because of polyelectrolyte absorbed on their surfaces. However, additional redispersion treatment such as ultrasonication is required to obtain dispersed suspensions because fine particles tend to agglomerate. The results demonstrate that ultrasonication is effective in improving particle dispersion in suspensions and producing a homogeneous fine microstructure of sintered materials. Superplastic tensile ductility is improved by ultrasonication in preparing suspensions because of the dense and homogeneous fine microstructure. 相似文献
42.
Tohru S. Suzuki Tetsuo Uchikoshi Yoshio Sakka 《Journal of the European Ceramic Society》2009,29(12):2627-2633
The preparation of oriented AlN bulk ceramics with and without additives was achieved by slip casting in a high magnetic field. The a and b axes of the AlN were aligned parallel to the direction of the magnetic field. The degree of crystallographic orientation was controlled by the viscosity of the slurry and the grain growth during sintering attributed to the sintering additives. The mechanical properties of the textured AlN depended on the direction of the crystallographic orientation. 相似文献
43.
Kenji Murao Tohru Kohda 《International Journal of Circuit Theory and Applications》1994,22(3):221-232
A simple switched capacitor (SC) circuit is given which realizes a one-dimensional discrete dynamical system Xn+1 = Xn + uxz generating intermittent chaos with a 1/f-shaped power spectrum. an integrated circuit with a pair of logarithmic and antilogarithmic amplifiters can easily realize the power-law term xz which plays a key role in generating l/fnoise. an inevitable small offset voltage ? in the SC circuit governs the cut-off frequency of 1/f noise, and when the dynamical system is modified by introducing an effective ?, the ‘indirect method’ enables us to get the precise power spectrum in the modified system. 相似文献
44.
Syoji Kobashi Yuji Fujiki Mieko Matsui Noriko Inoue Katsuya Kondo Yutaka Hata Tohru Sawada 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(1):74-86
Measurement of volume and surface area of the frontal, parietal, temporal and occipital lobes from magnetic resonance (MR) images shows promise as a method for use in diagnosis of dementia. This article presents a novel computer-aided system for automatically segmenting the cerebral lobes from 3T human brain MR images. Until now, the anatomical definition of cerebral lobes on the cerebral cortex is somewhat vague for use in automatic delineation of boundary lines, and there is no definition of cerebral lobes in the interior of the cerebrum. Therefore, we have developed a new method for defining cerebral lobes on the cerebral cortex and in the interior of the cerebrum. The proposed method determines the boundaries between the lobes by deforming initial surfaces. The initial surfaces are automatically determined based on user-given landmarks. They are smoothed and deformed so that the deforming boundaries run along the hourglass portion of the three-dimensional shape of the cerebrum with fuzzy rule-based active contour and surface models. The cerebrum is divided into the cerebral lobes according to the boundaries determined using this method. The reproducibility of our system with a given subject was assessed by examining the variability of volume and surface area in three healthy subjects, with measurements performed by three beginners and one expert user. The experimental results show that our system segments the cerebral lobes with high reproducibility. 相似文献
45.
Infectious mononucleosis due to Epstein-Barr virus (EBV) is almost always a self-limited disease, most commonly seen in young adults. Hepatitis is a well-recognized complication of EBV infection that usually resolves spontaneously. Jaundice occasionally results from the unusual complication of autoimmune haemolytic anaemia rather than hepatitis. We report a 60-year-old man with severe cholestatic jaundice whose history, liver histology and laboratory findings suggested EBV infection. He also developed significant jaundice related to his hepatitis, but not to autoimmune haemolysis, a situation that led to diagnostic delay. Costly diagnostic laboratory tests and invasive procedures were performed to rule out a malignant extrahepatic biliary obstruction. Physicians need to be aware of this complication and EBV infection should be included in the differential diagnosis of cholestatic jaundice in the elderly. 相似文献
46.
Following the presentation of the theory of powder formation in steady state electrocrystallization, some equations based on the linear instability theory in non-steady state deposition under diffusion control were derived; the galvanostatic case was then analysed using the theoretical equations obtained here.As a result, the dependences of powder growth and particle size on various physical parameters, such as current density, bulk concentration and temperature, were made quantitatively clear. Furthermore, a reliable basis was given to the induction time of powder formation which had formerly been liable to amibiguous discussion. 相似文献
47.
Hiroshi Nagai Yoshiki Takebayashi Hiroyasu Mitani 《Metallurgical and Materials Transactions A》1981,12(3):435-442
The isothermal oxidation resistance in air at 1273, 1323, and 1373 K of Fe-20Cr alloys with 1 wt pct dispersoid of Y203, La2O3, A12O3, TiO2, SiO2, Cr2O3 and without dispersoid prepared by a conventional sintering and rolling procedures was examined. It was found that SiO2 dispersoid reduced, while A12O3 dispersoid slightly increased the oxidation resistance. The dispersoids of TiO2 and Cr2O3 showed no beneficial effect on the oxidation resistance except for the oxidation after 10 h at 1373 K. The oxidation behavior
after 10 h at 1373 K was rather complex including accelerated oxidation. The beneficial effect of La2O3 and Y2O3 dispersoids was excellent at all temperatures. The oxidation rates during the early stage of oxidation for the alloys with
dispersoid were apparently dependent on the type of the dispersoid. There was no evidence that dispersoid accumulated at the
scale-alloy interface. Comparison of results obtained for the oxidation of the alloys prepared by a powder metallurgical procedure
with results for the alloys by arc-melting procedure indicated that the grain size of the alloy is an important factor for
reduction of oxidation rate but does not seem to be critical, because the grain size of the alloys with dispersoid was not
dependent on the type of the dispersoid. Ion Microanalyses of the Cr2O3 scale formed after 1 h oxidation at 1373 K showed an interesting feature in that all the dispersed elements were incorporated
in the scale and the iron content of the scale was lower on the alloys which exhibited better oxidation resistance. 相似文献
48.
Pertiwiningrum A Ino Y Suzuki T Iwama T Kawai K 《Journal of Bioscience and Bioengineering》2004,98(3):214-216
The cells of Streptomyces sp. YB-1 adsorbed 4-6 mg ytterbium (Yb) per g dry weight. The Yb contents of the cell wall fraction, cell-free extract, and cell membrane fraction were 11%, 2%, and 87%, respectively. The Yb content in the cell membrane fraction was 20-25 mg per g dry weight. The adsorbed Yb could be quantitatively desorbed by treating the cell membrane fraction with 1 mM EDTA and 1 M HCl at 37 degrees C for 4 h. Treatment with 1 M NaOH caused Yb desorption to some extent. Treatments with proteinase K, lysozyme, 0.5% Triton X-100, 0.4% sodium dodecyl sulfate, and 1 M NaCl did not cause Yb desorption. Elemental analysis of Yb-adsorbed materials after removal of proteins and then extraction of lipids from the membrane fraction revealed that the molar ratio of Yb and P in the materials was about 1:1. The cells and the membrane fraction could be used repeatedly as a bioadsorbent for Yb. 相似文献
49.
Kamino T Yaguchi T Kuroda Y Ohnishi T Ishitani T Miyahara Y Horita Z 《Journal of electron microscopy》2004,53(5):459-463
Transmission electron microscopy (TEM) samples of an Mg-Al alloy has been prepared using a Ga-focused ion beam (FIB) milling at two different operating voltages of 10 kV and 40 kV to investigate the influence of the FIB energy on the sample quality. The fine structures of the samples have been studied using a high resolution TEM, and the concentration of the implanted Ga was analysed using an energy dispersive X-ray (EDX) analysis. The result of the TEM observation revealed that point defects were introduced to the sample finally milled at 40 kV but not at 10 kV. However, crystal lattice images and electron diffraction patterns were clearly observed on both the samples. The typical influence of the FIB energy was indicated in the elemental analysis. The relative Ga concentration in the thin sample finally milled at 10 kV was 1.0-2.0 at% that is less than half of 4.0-6.0 at% of the Ga concentration in the sample finally milled at 40 kV. A comparison between the experimental results of the Ga concentration measurement with simulation was also discussed. 相似文献
50.
Tanaka N Kimura H Tokuda D Hosoya K Ikegami T Ishizuka N Minakuchi H Nakanishi K Shintani Y Furuno M Cabrera K 《Analytical chemistry》2004,76(5):1273-1281
Simple and comprehensive two-dimensional (2D)-HPLC was studied in a reversed-phase mode using monolithic silica columns for second-dimension (2nd-D) separation. Every fraction from the first column, 15 cm long (4.6-mm i.d.), packed with fluoroalkylsilyl-bonded (FR) silica particles, was subjected to the separation in the 2nd-D using one or two octadecylsilylated (C(18)) monolithic silica columns (4.6-mm i.d., 3 cm). Monolithic silica columns in the 2nd-D were eluted at a flow rate of up to 10 mL/min with separation time of 30 s that meets the fractionation every 15-30 s at the first dimension (1st-D) operated at a flow rate of 0.4-0.8 mL/min. Three cases were studied. (1) In the simplest scheme of 2D-HPLC, effluent of the 1st-D was directly loaded into an injector loop of 2nd-D HPLC for 28 s, and 2 s was allowed for injection. (2) Two six-port valves each having a sample loop were used to hold the effluent of the 1st-D alternately for 30 s for one 2nd-D column to effect comprehensive 2D-HPLC without the loss of 1st-D effluent. (3) Two monolithic silica columns were used for 2nd-D by using a switching valve and two sets of 2nd-D chromatographs separating each fraction of the 1st-D effluent with the two 2nd-D columns alternately. In this case, two columns of the same stationary phase (C(18)) or different phases, C(18) and (pentabromobenzyloxy)propylsilyl-bonded (PBB), could be employed at the 2nd-D, although the latter needed two complementary runs. The systems produced peak capacity of approximately 1000 in approximately 60 min in cases 1 and 2 and in approximately 30 min in case 3. The three stationary phases, FR, C(18), and PBB, showed widely different selectivity from each other, making 2D separations possible. The simple and comprehensive 2D-HPLC utilizes the stability and high efficiency at high linear velocities of monolithic silica columns. 相似文献