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241.
Yoji Koike Sei-ichi Tanuma Hiroyoshi Suematsu Kohei Higuchi 《Journal of Physics and Chemistry of Solids》1980,41(10):1111-1118
Superconducting properties of pseudo-single crystals of C8K were investigated by low frequency a.c. magnetic susceptibility and electrical resistivity measurements. The measured values of Tc were between 128 and 198 mK for 13 samples. Measurements of the superconducting transition in a magnetic field revealed a remarkable anisotropy, such that if θ is defined as the angle between the applied magnetic field and the layer plane, type II superconductivity was observed for 0° ≦ ∣ θ ∣ ? 25° and type I superconductivity for 25° ? ∣ θ ∣≦ 90°. The angular dependences of Hc2 and Hc3 were fairly well-explained by the effective mass model. 相似文献
242.
Mössbauer spectra were observed for amorphous Fe-Ti alloys produced by vapor quenching. The average values of the hyperfine field, the quadrupole splitting and the isomer shift vary gradually with increase in Ti concentration. After being annealed at 400°C for few hours, the amorphous phase is maintained around 33 at % Ti, while an intermediate phase, Ti2Fe, appears around 67 at % Ti. 相似文献
243.
This paper presents a theorem concerning a matroid with the parity condition. The theorem provides matroid generalizations of graph-theoretic results of Lewin and Gallai. 相似文献
244.
Yoji Maeda Hisaaki Kanetsuna Katsuharu Tagashira Tetuo Takemura 《Journal of Polymer Science.Polymer Physics》1981,19(9):1325-1331
The relation between the thermal behavior of extended-chain crystals (ECCs) of polyethylene and the phase transitions, i.e., orthorhombic ? hexagonal ? melt, of polyethylene at high pressures above about 400 MPa has been studied by high-pressure differential thermal analysis (DTA), and with a high-pressure and high-temperature x-ray diffraction apparatus equipped with a position-sensitive proportional counter measuring system. The original sample used in this study consists mainly of two kinds of ECC, which we designate as “ordinary extended-chain” crystals (OECCs) and “highly-extended-chain” crystals (HECCs). Experimental results at pressures below 300 MPa substantiate the results previously reported: i.e., the phase diagram indicating the relation between the melting temperatures and pressure for the OECCs and HECCs can be determined for pressures up to 500 MPa. In heating at pressures above about 500 MPa, the peak intensity of the (100) reflection of the hexagonal structure decreases in two stages with increasing temperature. The phenomenon corresponds to the thermal behavior determined by high-pressure DTA in which two small endothermic peaks can be observed at temperatures above that of the crystal transition evidenced by the strong peak. This phenomenon suggests melting in two stages of hexagonal structures with different thermal stabilities, and that the change at higher temperature may be due to fusion of the hexagonal phase annealed either below or above the transition temperature. 相似文献
245.
We explore the optimality of balanced Feistel ciphers with SP-type F-functions with respect to their resistance against differential and linear cryptanalysis. Instantiations of Feistel ciphers with the wide class of (SP) \(^u\) and (SP) \(^u\) S F-functions are considered: one F-function can contain an arbitrary number of S-box layers interleaved with linear diffusion. For the matrices with maximum diffusion, it is proven that SPS and SPSP F-functions are optimal in terms of the proportion of active S-boxes in all S-boxes—a common efficiency metric for substitution-permutation ciphers. Interestingly, one SP-layer in the F-function is not enough to attain optimality whereas taking more than two S-box layers does not increase the efficiency either. 相似文献
246.
Songbai Cheng Daisuke HiraharaYouhei Tanaka Yoji GondaiBin Zhang Tatsuya MatsumotoKoji Morita Kenji FukudaHidemasa Yamano Tohru SuzukiYoshiharu Tobita 《Experimental Thermal and Fluid Science》2011,35(2):405-415
A series of experiments on bubbling behavior in particle beds was performed to clarify three-phase flow dynamics in debris beds formed after core-disruptive accident (CDA) in sodium-cooled fast breeder reactors (FBRs). Although in the past, several experiments have been performed in packed beds to investigate flow patterns, most of these were under comparatively higher gas flow rate, which may be not expected during an early sodium boiling period in debris beds. The current experiments were conducted under two dimensional (2D) and three dimensional (3D) conditions separately, in which water was used as liquid phase, and bubbles were generated by injecting nitrogen gas from the bottom of the viewing tank. Various particle-bed parameters were varied, including particle-bed height (from 30 mm to 200 mm), particle diameter (from 0.4 mm to 6 mm) and particle type (beads made of acrylic, glass, alumina and zirconia). Under these experimental conditions, three kinds of bubbling behavior were observed for the first time using digital image analysis methods that were further verified by quantitative detailed analysis of bubbling properties including surface bubbling frequency and surface bubble size under both 2D and 3D conditions. This investigation, which hopefully provides fundamental data for a better understanding and an improved estimation of CDAs in FBRs, is expected to benefit future analysis and verification of computer models developed in advanced fast reactor safety analysis codes. 相似文献
247.
Takai A Ataee-Esfahani H Doi Y Fuziwara M Yamauchi Y Kuroda K 《Chemical communications (Cambridge, England)》2011,47(27):7701-7703
A new type of platinum nanowire with a bumpy surface "Pt nanoworm" is electrochemically synthesized in mesochannels of mesoporous silica films with the assistance of a nonionic surfactant (C(16)EO(8)). 相似文献
248.
The phase behaviour of the thermotropic cubic mesogen 1,2-bis(4′-n-hexyloxybenzoyl)hydrazine [BABH(6)] was investigated under pressure up to about 55 MPa using a polarising optical microscope equipped with a high-pressure optical cell. BABH(6) shows the crystal (Cr)–cubic (Cub)–isotropic liquid (I) phase transition at ambient pressure on heating. The smectic C (SmC) phase was induced above 32 MPa, showing the unusual phase sequence of Cr–Cub–SmC–I, similar to those in BABH(n) (n = 8–10). The boundary between the Cub and SmC phases exhibited a negative slope dT/dP of about –1.0 ºC MPa?1. 相似文献
249.
The phase transition behaviour of three homologous discotic mesogens, the hexa‐n‐alkoxyanthraquinones HOAQ(n), n indicating the number of carbon atoms in the alkoxy group, was investigated under hydrostatic pressures up to 500?MPa using a high pressure differential thermal analyser. The T vs. P phase diagrams of HOAQ(6), HOAQ(8) and HOAQ(9) were constructed for solution‐ (Cr0) and melt‐crystallized (Cr1) samples of the compounds. HOAQ(6) shows the reversible Cr0–rectangular columnar phase (Colr)–hexagonal columnar phase (Colh)–isotropic liquid (I) phase sequence at atmospheric pressure. The stable Colr phase of HOAQ(6) has a decreased temperature range with increasing pressure and then the Colr phase disappears under pressures above about 350?MPa; instead the Cr0–Colh–I phase sequence is exhibited. For HOAQ(8), the solution‐grown sample exhibits the stable Cr0–Colh–I phase sequence at atmospheric pressure. Applying pressure to the solution‐grown sample induces the formation of the stable Colr phase in the pressure region between 10 and 350?MPa, leading to the Cr0–Colr–Colh–I phase sequence. The pressure‐induced Colr phase disappears under higher pressures. The melt‐cooled sample of HOAQ(8) shows the formation of the metastable crystal (Cr1), unknown mesophase (X) and Colr phases at lower temperatures under atmospheric pressure, and exhibits the reversible Cr1–X–Colr–Colh–I phase sequence on subsequent thermal cycles. The metastable phase sequence was observed under pressures up to 100?MPa, but the phase transitions were too small to be detected under higher pressures. In HOAQ(9) the stable Cr0–Colh–I phase sequence is observed at all pressures, while the melt‐cooled sample shows the metastable Cr1–Colr–Colh–I phase sequence under pressures up to 300?MPa. The metastable Colr phase disappears under higher pressures. 相似文献
250.