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51.
52.
Syntheses of Spinon Thermal Conductivity Materials in Sr–Cu–O System by Glass‐Ceramics Technique
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Nobuaki Terakado Yuudai Yokochi Kouki Watanabe Yoshihiro Takahashi Takumi Fujiwara 《Journal of the American Ceramic Society》2016,99(5):1565-1572
We have synthesized spinon thermal conductivity materials in Sr–Cu–O system by glass‐ceramics technique. The materials are promising for active control of thermal energy in microelectronic devices because of high and anisotropic thermal conduction, its controllability, and electric insulation. Nevertheless, research on these materials has been limited to that concerning theoretical perspectives and investigation of physical properties using large single crystals. In this study, we adopt glass‐ceramics technique to synthesize these materials: We prepared melt‐quenched multicomponent oxides including SrO and CuO, and checked its glass‐forming ability and crystallization behaviors by heating. As a result, we have found that SrCuO2 and Sr14Cu24O41, known as the spinon thermal conductivity materials, are synthesized using SrO–CuO–?Li2O–?Al2O3?–Ga2O3 system. This synthesis process for the system will provide practical application of the spinon thermal conductivity materials. 相似文献
53.
Kentaro Fujimoto Yoshiyasu Matsumoto Kohki Oikawa Jun-ichi Nomura Yasuyoshi Shimada Shunrou Fujiwara Kazunori Terasaki Masakazu Kobayashi Kenji Yoshida Kuniaki Ogasawara 《International journal of molecular sciences》2016,17(8)
The purpose of the present study was to determine whether cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during exposure of the carotid arteries in carotid endarterectomy (CEA). In patients undergoing CEA for internal carotid artery stenosis (≥70%), cerebral blood flow (CBF) was measured using single-photon emission computed tomography (SPECT) before and immediately after CEA. Microembolic signals (MES) were identified using transcranial Doppler during carotid exposure. Diffusion-weighted magnetic resonance imaging (DWI) was performed within 24 h after surgery. Of 32 patients with a combination of reduced cerebrovascular reactivity to acetazolamide on preoperative brain perfusion SPECT and MES during carotid exposure, 14 (44%) showed cerebral hyperperfusion (defined as postoperative CBF increase ≥100% compared with preoperative values), and 16 (50%) developed DWI-characterized postoperative cerebral ischemic lesions. Postoperative cerebral hyperperfusion was significantly associated with the absence of DWI-characterized postoperative cerebral ischemic lesions (95% confidence interval, 0.001–0.179; p = 0.0009). These data suggest that cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during carotid exposure in CEA, supporting the “impaired clearance of emboli” concept. Blood pressure elevation following carotid declamping would be effective when embolism not accompanied by cerebral hyperperfusion occurs during CEA. 相似文献
54.
Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) is an engineering plastic with high heat distortion temperature. Melt processing of neat PPE is usually accompanied with thermal degradation. The degradation problem is solved by blending with polystyrene to reduce the processing temperature. We propose an alternative using triallylisocyanurate (TAIC). TAIC is a low viscosity liquid that can be cured by peroxide, e.g. α,α′-bis(t-butylperoxy-m-isopropyl)benzene (PBP), to provide a thermoset. The PPE/TAIC mixture was shown to have the upper critical solution temperature (UCST) type phase behavior. At the single-phase regime above UCST and below the cure temperature (∼180°C for PBP), the mixture had a low viscosity, less viscous than a conventional thermoplastic such as PC and PP. That is, a nice window for injection molding was available, e.g., at 100°C to 160°C for a 50/50 blend. After injecting into a hot mold set at cure temperature, the blend cured in a short time (∼80% conversion in 5 min). Then the molded and partly cured material kept its shape and dimensions during post-cure in a hot chamber at higher temperature (e.g. 250°C). Using transmission electron microscopy and dynamic mechanical analyses, it was shown that the cured blend had a bicontinuous two-phase structure with periodic spacings of ∼30 nm, suggesting a structure formation via a spinodal decomposition driven by the increase in molecular weight of TAIC during cure. The cured material showed excellent flexural strength and high chemical resistance. 相似文献
55.
Flip chip technology with Au bumps on a substrace has been widely applied to electronic equipment such as smart phones. The purposes of this study are to examine the effect of Al pad thickness on the bondability of flip chip using ultrasonic bonding and to clarify interfacial structures between Au alloy bumps and Al pads by ultrasonic bonding compared before and after a thermal cycle test. Suitable Al thickness for excellent initial Au/Al bonding without chip cracking are 0.8 μm because a thin Al layer could not reduce stress to a chip under an Al pad during the ultrasonic bonding process. Intermetallic compounds between the Au alloy bump and chip after reflows consisted of five Au-Al layers, and a pure Al layer remained. On the other hand, after the temperature cycle test at 218/423 K, intermetallic compounds between the Au alloy bump and chip were changed into two kinds of Au-Al layers, so a pure Al layer did not exist. In addition, if thick intermetallic compound layers existed around the bonding region, bondability deteriorated easily by thermal stress due to a thermal cycle test, therefore the open failure rate was rising when the Au thickness was 1.2 μm. 相似文献
56.
T. Komatsu R. Ihara T. Honma Y. Benino R. Sato H.G. Kim T. Fujiwara 《Journal of the American Ceramic Society》2007,90(3):699-705
This paper reports recent progress in the patterning of non-linear optical crystals on the glass surface by laser irradiation. Two techniques for the writing of crystal lines have been developed, i.e., rare-earth (samarium) atom heat processing and transition metal atom heat processing, in which a continuous wave Nd:YAG laser (wavelength: λ=1064 nm) is irradiated to the glasses containing rare-earth (RE: Sm3+ , Dy3+ ) ions or transition metal (TM: Ni2+ , Fe2+ , V4+ ) ions. The writing of crystal lines such as β-BaB2 O4 , Sm x Bi1− x BO3 , and Ba2 TiGe2 O8 showing second harmonic generations has been successful. It is clarified from the azimuthal dependence of second harmonic intensity and polarized micro-Raman scattering spectra that crystal lines consist of highly oriented crystals along the crystal line growth direction. It is also possible to write two-dimensional crystal bending or curved lines by just changing the laser scanning direction. The mechanism of the laser-induced crystallization has been proposed. 相似文献
57.
Kotaro Hama Yuko Fujiwara Masashi Morita Fumiyoshi Yamazaki Yuko Nakashima Shiro Takei Shigeo Takashima Mitsutoshi Setou Nobuyuki Shimozawa Tsuneo Imanaka Kazuaki Yokoyama 《Lipids》2018,53(1):85-102
ABCD1 is a gene responsible for X‐linked adrenoleukodystrophy (X‐ALD), and is critical for the transport of very long‐chain fatty acids (VLCFA) into peroxisomes and subsequent β‐oxidation. VLCFA‐containing lipids accumulate in X‐ALD patients, although the effect of ABCD1‐deficiency on each lipid species in the central nervous system has not been fully characterized. In this study, each phospholipid and lysophospholipid species in Abcd1‐deficient mice brains were profiled by liquid chromatography‐mass spectrometry. Among the phospholipid and lysophospholipid species that are significantly more enriched in Abcd1‐deficient mice brains, VLCFA were present in 75, 15, 5, 4, and 1 species of phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, lysophosphatidylcholine, and lysophosphatidylethanolamine, respectively. Most VLCFA were incorporated at the sn‐1 position of phosphatidylcholine and phosphatidylethanolamine. Among the phospholipid species that are significantly less enriched in Abcd1‐deficient mice brains, odd‐numbered saturated or mono‐unsaturated fatty acyl moieties are contained in all phosphatidylcholine species. In addition, a number of phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine species contained highly unsaturated fatty acyl moieties. Intriguingly, 44:1 phosphatidylcholine with VLCFA was mainly distributed in the gray matter, such as the cortex, but not in the white matter in the cerebrum and cerebellum. These results show that ABCD1‐deficiency causes metabolic alternation of long‐chain fatty acids and VLCFA. Moreover, our results imply a molecular mechanism for the incorporation of saturated or monounsaturated VLCFA into the sn‐1 position of phospholipids, and also indicate that the distribution of phospholipids with VLCFA may correlate with the development of X‐ALD. 相似文献
58.
A method is presented for configuration optimization of frames that have specified properties on nodal displacements, stresses, and reaction forces against static loads. The conventional ground structure approach is first used for topology optimization. A feasible solution with a small number of members satisfying all the design requirements except the stress constraints is obtained by assigning artificially small upper-bound displacement, or by penalizing the stiffness of a thin member. This way, the well-known difficulty in topology optimization under stress constraints is successfully avoided. The nodal locations and cross-sectional areas of the feasible solution are next optimized to obtain an approximate optimal configuration under stress constraints. The proposed method is applied to the design of self-fastening clamping members for membrane structures modeled using frame elements. An optimization result is also presented for a clamping member that adjusts deformation of membrane by applying a clamping force with a vertically attached bolt. 相似文献
59.
K.Fujiyama T.Fujiwara Y.Nakatani K.Saito A.Sakuma Y.Akikuni S.Hayashi S.Matsumoto 《金属学报(英文版)》2004,17(4):338-344
Statistical manipulation of material data was conducted for probabilistic life assessment or risk-based design and maintenance for high temperature components of power plants. To obtain the statistical distribution of material properties, dominant parameters affecting material properties are introduced into normalization of statistical variables. Those parameters are hardness, chemical composition, characteristic microstructural features and so on. Creep and fatigue properties are expressed by normalized parameters and the unified statistical distributions are obtained. These probability distribution functions show good coincidence statistically with the field database of steam turbine components. It was concluded that the unified statistical baseline approach is useful for the risk management of components in power plants. 相似文献
60.
Ryosuke Iwai Yoko Kumagai Masashi Fujiwara Shigeyuki Wakitani Mutsumi Takagi 《Journal of Bioscience and Bioengineering》2010,110(5):593-596
High-expression plasmid vectors for human mesenchymal stem cells (MSCs) were constructed by combination of cytomegalovirus immediate-early enhancer with cellular promoters. MSCs transfected with the vector showed higher transgene production of a cytokine, which increased the differentiation level to chondrocytes. 相似文献