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411.
Electrical and optical properties of an argon plasma jet were characterized. In particular, effects of an additive gas, namely nitrogen or oxygen, on these prop... 相似文献
412.
Gujar TP Anand C Shinde VR Ye J Ariga K Vinu A 《Journal of nanoscience and nanotechnology》2010,10(12):8124-8129
Mesoporous TiO2 powder materials with a high crystallinity have been prepared by evaporation induced self assembly (EISA) process using titanium tetraisopropoxide (TTIP) and pluronic P123 surfactant (EO20PO70EO20) as titanium source and structure-directing reagent, respectively. The prepared materials were characterized by low and wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical absorption, and N2 adsorption-desorption experiments. The crystallinity of the materials was controlled by varying the calcination temperature. The resulting TiO2 materials showed highly crystalline structure with uniform particle size which increases from 11.8 to 23.8 nm with increasing the calcination temperature from 400 to 600 degrees C, respectively, whereas the specific surface area decreases from 125 to 40 m2/g. TEM and XRD results revealed that the calcination temperature of 600 degrees C is the best condition to obtain highly crystalline mesoporous TiO2. The photocatalytic activity of the TiO2 mesoporous materials with different crystallinity and textural parameters has been studied in the decomposition of methylene blue (MB) dye molecules under visible light irradiation. Among the mesoporous TiO2 materials studied, the material with the highest crystallinity, prepared at 600 degrees C, showed the best photocatalytic performance in the decomposition of MB under visible light in a short time. 相似文献
413.
Jun’ichi Hayashi Mikihito UchibayashiToshihide Horikawa Katsuhiko MuroyamaVincent G Gomes 《Carbon》2002,40(15):2747-2752
We prepared activated carbons from phenol-formaldehyde (PF) and urea-formaldehyde (UF) resins by chemical activation with K2CO3 with impregnation during the synthesis of the resins. The influence of carbonization temperature (773-1173 K) on the pore structure (specific surface area and pore volume) and the temperature range at which K2CO3 worked effectively as an activation reagent, were investigated. The specific surface area and micropore volume of PF-AC and UF-AC increased with an increase of carbonization temperature in the range of 773-1173 K. We prepared activated carbon with well-developed micropores from PF, and activated carbon with high specific surface area (>3000 m2/g) and large meso-pore volume from UF. We deduced the activation mechanism with thermogravimetry and X-ray diffraction. In preparing activated carbon from PF, K2CO3 was reduced by carbon in the PF char. The carbon was removed as CO gas resulting in increased specific surface area and pore volume above 1000 K. In preparing AC from UF, above 900 K the carbon in UF char was consumed during the K2CO3 reduction step. 相似文献
414.
Junichiro Mizusaki† Hiroaki Tagawa Kei Hayakawa Katsuhiko Hirano 《Journal of the American Ceramic Society》1995,78(7):1781-1786
The high-temperature phase relationship and thermal expansion coefficient of YBa2 Cu3 O7-x under constant oxygen nonstoichiometry, x, were determined by high-temperature powder X-ray diffraction analysis under controlled oxygen partial pressure at temperatures up to 800deg; C. The results are discussed based on reported nonstoichiometry data. The present study showed an orthorhombic-to-tetragonal transition near the composition x = 0.5. The lattice parameter c, perpendicular to the Cu-O plane, showed a maximum at around x = 0.7 to 0.8. In the ortho-rhombic phase, the lattice parameters a and b along the Cu-O plane were essentially constant for x < 0.2. For 0.2 < x < ∼ 0.5, a increased and b decreased with x. In the tetragonal phase, with x < ∼ 0.5, the lattice parameter a decreased with x. The thermal expansion coefficient, α, along the c-axis ranged from 19 × 10-6 to 25 × 10-6 -K-1 , whereas a along the a- and b-axes ranged from 12 × 10-6 to 22 × 10-6 -K-1 at 400° to 800deg; C, and these values were very small below 400deg; C. It was found that a, b, and α along the a- and b-axes are smaller when the oxygen content along the respective axes is less, while the area of the ab plane and its thermal expansion coefficient are larger when the deviation of the oxygen content from the stoichiometric compositions of YBa2 Cu3 O7 or YBa2 Cu3 O6 is larger. Changes of x and temperature affected c more strongly than a and b. 相似文献
415.
Fuminori Arai Hiroki Takeshita Masako Dobashi Katsuhiko Takenaka Masamitsu Miya Tomoo Shiomi 《Polymer》2012,53(3):851-856
To analyze the interplay between crystallization and liquid–liquid phase separation (LLPS), isothermal crystallization behavior of poly(ethylene glycol) (PEG) in blends with isotactic poly(methyl methacrylate) (i-PMMA) was investigated by differential scanning calorimetry (DSC). The blend system had an upper critical solution temperature (UCST) type phase diagram. When the crystallization occurred simultaneously with LLPS, the overall crystallization rate was enhanced at high crystallization temperatures Tc, relatively compared with that of neat PEG. This behavior was interpreted by the combination of the effects of spinodal quench depth ?Ts and usual supercooling degree ?Tc, according to the theory of Mitra and Muthukumar, namely, the crystallization rate is enhanced by the concentration fluctuation-assisted nucleation at high Tc. In the crystallization after LLPS proceeded, on the other hand, the overall crystallization rate was slow and less dependent on the blend composition. In addition, it was revealed by small-angle X-ray scattering measurements that amorphous i-PMMA was excluded from the interlamellar region of PEG crystals in SQ as well as WQ. 相似文献
416.
Masaki Mitsunaga Yasuhito Ito Suprakas Sinha Ray Masami Okamoto Katsuhiko Hironaka 《大分子材料与工程》2003,288(7):543-548
Intercalated polycarbonate (PC)/clay nanocomposites (PCCN)s have been prepared successfully through the melt intercalation method in the presence of a compatibilizer. The internal structure and morphology of the PCCNs has been established by using wide‐angle X‐ray diffraction (WAXD) analyses and transmission electron microscopic (TEM) observations. The morphology of these nanocomposites and degradation of the PC matrix after nanocomposites preparation can be controlled by varying surfactants used for the modification of clay and compatibilizer. The intercalated PCCNs exhibited remarkable improvements of mechanical properties when compared with PC without clay. We also discuss foam processing of one representative PCCN using supercritical CO2 as a foaming agent.
417.
Sudaryanto Takashi Nishino Masaki Ueno Seiji Asaoka Katsuhiko Nakamae 《应用聚合物科学杂志》2001,82(12):3022-3029
Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X‐ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard‐segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard‐segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3022–3029, 2001 相似文献
418.
Masahito Yamamoto Koji Sakiyama Kei Kitamura Yutaro Yamamoto Takahiro Takagi Sayo Sekiya Genji Watanabe Shuichiro Taniguchi Yudai Ogawa Satoshi Ishizuka Yuki Sugiyama Takeshi Takayama Katsuhiko Hayashi Wei-Jen Chang Shinichi Abe 《International journal of molecular sciences》2022,23(6)
Owing to a rapid increase in aging population in recent years, the deterioration of motor function in older adults has become an important social problem, and several studies have aimed to investigate the mechanisms underlying muscle function decline. Furthermore, structural maintenance of the muscle–tendon–bone complexes in the muscle attachment sites is important for motor function, particularly for joints; however, the development and regeneration of these complexes have not been studied thoroughly and require further elucidation. Recent studies have provided insights into the roles of mesenchymal progenitors in the development and regeneration of muscles and myotendinous junctions. In particular, studies on muscles and myotendinous junctions have—through the use of the recently developed scRNA-seq—reported the presence of syncytia, thereby suggesting that fibroblasts may be transformed into myoblasts in a BMP-dependent manner. In addition, the high mobility group box 1—a DNA-binding protein found in nuclei—is reportedly involved in muscle regeneration. Furthermore, studies have identified several factors required for the formation of locomotor apparatuses, e.g., tenomodulin (Tnmd) and mohawk (Mkx), which are essential for tendon maturation. 相似文献
419.
Artenis Bendo Kenji Matsuda Katsuhiko Nishimura Norio Nunomura Taiki Tsuchiya Seungwon Lee 《Materials Science & Technology》2020,36(15):1621-1627
Metastable phases in aluminium alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminium alloys is associated with the phase transformation from clusters or GP-zones to the metastable η′ phase. The high-resolution electron imaging is used to observe the precipitates and reconstruct a kinetic model that might explain the transformation. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of the η′ phase. 相似文献
420.
In situations of power outage or shortage, such as periods just following a seismic disaster, the only reliable power source available is the most fundamental of forces i.e., manual mechanical stimuli. Although there are many macroscopic mechanical tools, mechanical control of nanomaterials and nanosystems has not been an easy subject to develop even by using advanced nanotechnological concepts. However, this challenge has now become a hot topic and many new ideas and strategies have been proposed recently. This report summarizes recent research examples of mechanical control of nanomaterials and nanosystems. Creation of macroscopic mechanical outputs by efficient accumulation of molecular-level phenomena is first briefly introduced. We will then introduce the main subject: control of molecular systems by macroscopic mechanical stimuli. The research described is categorized according to the respective areas of mechanical control of molecular structure, molecular orientation, molecular interaction including cleavage and healing, and biological and micron-level phenomena. Finally, we will introduce two more advanced approaches, namely, mechanical strategies for microdevice fabrication and mechanical control of molecular machines. As mechanical forces are much more reliable and widely applicable than other stimuli, we believe that development of mechanically responsive nanomaterials and nanosystems will make a significant contribution to fundamental improvements in our lifestyles and help to maintain and stabilize our society. 相似文献