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111.
Yoshihisa Kosugi Masato Goto Zhenhong Tan Asaya Fujita Takashi Saito Takashi Kamiyama Wei-Tin Chen Yu-Chun Chuang Hwo-Shuenn Sheu Daisuke Kan Yuichi Shimakawa 《Advanced functional materials》2021,31(25):2009476
Materials which show novel thermal properties can be used to make highly efficient and environmentally friendly energy systems for thermal energy storage and refrigeration through caloric effects. An A-site-ordered quadruple perovskite-structure oxide, NdCu3Fe4O12, is found to release significant latent heat, 25.5 kJ kg−1 (157 J cc−1), at the intersite-charge-transfer transition temperature near room temperature. The transition is first-order and accompanied by an unusual magnetic ordering and a large negative-thermal-expansion-like volume change, and thus, it causes a large entropy change (84.2 J K−1 kg−1). The observed entropy change is comparable to the largest changes reported in inorganic solid materials, and more importantly, it is utilized through a colossal barocaloric effect. The adiabatic temperature change by applying 5.1 kbar pressure is estimated to reach 13.7 K, which means efficient refrigeration can be realized through this effect. 相似文献
112.
113.
Joshua Hoemke Eita Tochigi Tetsuya Tohei Hidehiro Yoshida Naoya Shibata Yuichi Ikuhara Yoshio Sakka 《Journal of the American Ceramic Society》2018,101(6):2616-2626
The development of inversion domain networks consisting of basal‐plane and pyramidal‐plane inversion domain boundary (b‐IDB and p‐IDB) interfaces within grains in Sn‐Al dual‐doped ZnO (Zn0.98Sn0.01Al0.01O) polycrystalline ceramics has been confirmed using transmission electron microscopy. The atomic structure of the b‐IDB and p‐IDB interfaces has been analyzed using atomic‐resolution scanning transmission electron microscopy. The localization of Sn and Al at the respective sites of the b‐IDBs and p‐IDBs was confirmed by energy‐dispersive X‐ray spectroscopy. In contrast to Sn or Al single‐dopant addition to ZnO, which results in the formation of spinel phase precipitates without the development of inversion domain networks, Sn‐Al dual‐doping caused the suppression of spinel phase formation and the formation of monophasic inversion domain networks composed of RMO3(ZnO)n homologous phase compound members, where R and M represent dopants substituting at the b‐IDB and p‐IDB sites, with a general formula of SnAlO3(ZnO)n. The results of this study demonstrate that the formation of inversion domain networks in ZnO‐based ceramics can be stabilized via multiple‐dopant addition. This finding has potential implications for the modification of the bulk or nanoscale properties based on the choice of the specific dopants, R and M, the control of the ratio R:M and the value of n in the RMO3(ZnO)n homologous phase compound members constituting the inversion domain networks. 相似文献
114.
Inversion domain boundaries in Mn and Al dual‐doped ZnO: Atomic structure and electronic properties 下载免费PDF全文
Joshua Hoemke Eita Tochigi Tetsuya Tohei Hidehiro Yoshida Naoya Shibata Yuichi Ikuhara Yoshio Sakka 《Journal of the American Ceramic Society》2017,100(9):4252-4262
The atomic and electronic structures of inversion domain boundaries in Mn‐Al dual‐doped ZnO (Zn0.89Mn0.1Al0.01O) have been investigated. Using atomic‐resolution scanning transmission electron microscopy, a head‐to‐head c‐axis configuration and cation stacking sequence of αβαβ|γ|αβαβ along the c‐axis were observed at the basal‐plane inversion domain boundary. Energy‐dispersive X‐ray spectroscopy and electron energy‐loss spectroscopy revealed significant localization of Mn and minor localization of Al at the basal‐plane inversion domain boundary. Based on experimental findings, a Mn‐doped basal‐plane inversion domain boundary slab model was constructed and refined by first principles calculations. The model is in agreement with atomic‐resolution images. The local electronic density of states of the slab model basal‐plane inversion domain boundary shows a hybridization of the Mn d and O p states within the valence band and localized Mn d states in the conduction band. The thermoelectric properties of Zn0.99?xMnxAl0.01O ceramics have been reported in a previous work. In this work, the effects of inversion domain boundaries on the thermoelectric properties are discussed. In comparison to Zn0.99?xMnxAl0.01O ceramics with x≤0.05, inversion domain boundaries in Zn0.89Mn0.1Al0.01O caused thermal and electrical conductivity reduction due to interface scattering of phonons and electrons. The Seebeck coefficient increased, suggesting electron filtering at inversion domain boundaries. 相似文献
115.
Chingunpitak J Puttipipatkhachorn S Chavalitshewinkoon-Petmitr P Tozuka Y Moribe K Yamamoto K 《Drug development and industrial pharmacy》2008,34(3):314-322
The purpose of this study was to investigate the formation of drug nanoparticles from binary and ternary mixtures, consisting of dihydroartemisinin (DHA), a poorly water-soluble antimalarial drug, with water-soluble polymer and/or surfactant. Binary mixtures of drug/polyvinyl pyrrolidone K30 (PVP K30), binary mixtures of drug/sodium deoxycholate (NaDC), and ternary mixtures of drug/PVP K30/NaDC were prepared at different weight ratios and then ground by vibrating rod mill to obtain ground mixtures. Nanosuspension was successfully formed after dispersing ternary ground mixtures or DHA/NaDC ground mixtures in water. The ternary ground mixtures did not give superior nanosuspension in terms of particle size reduction and recovery of drug nanoparticles, but they provided more physically stable nanosuspensions than DHA/NaDC ground mixtures. The size of drug nanoparticles was decreased with increasing grinding time and lowering amount of PVP K30 and NaDC. About 95% of drug nanoparticles were found in the nanosuspension from ternary ground mixtures. Zeta potential measurement suggested that stable nanosuspension was attributable to adsorption of NaDC and PVP K30 onto surface of drug particles. Atomic force microscopy and transmission electron microscopy with selected area diffraction indicated that DHA in nanosuspension was existed as nanocrystals. The obtained nanosuspensions had higher in vitro antimalarial acitivity against Plasmodium falciparum than microsuspensions. The results suggest that co-grinding of DHA with PVP K30 and NaDC seems to be a promising method to prepare DHA nanosuspension. 相似文献
116.
Kokubo T Ueda T Kawashita M Ikuhara Y Takaoka GH Nakamura T 《Journal of materials science. Materials in medicine》2008,19(2):695-702
A rectangular specimen of polyethylene terephthalate (PET) was soaked in a titania solution composed of titanium isopropoxide,
water, ethanol and nitric acid at 25 °C for 1 h. An amorphous titanium oxide was formed uniformly on the surface of PET specimen,
but did not form an apatite on its surface in a simulated body fluid (SBF) within 3 d. The PET plate formed with the amorphous
titanium oxide was subsequently soaked in water or HCl solutions with different concentrations at 80 °C for different periods
of time. The titanium oxide on PET was transformed into nano-sized anatase by the water treatment and into nano-sized brookite
by 0.10 M HCl treatment at 80 °C for 8 d. The former did not form the apatite on its surface in SBF within 3 d, whereas the
latter formed the apatite uniformly on its surface. Adhesive strength of the titanium oxide and apatite layers to PET plate
was increased by pre-treatment of PET with 2 wt% NaOH solution at 40 °C for 2 h. A two-dimensional fabric of PET fibers 24 μm
in diameter was subjected to the NaOH pre-treatment at 40 °C, titania solution treatment at 25 °C and subsequent 0.10 M HCl
treatment at 80 °C. Thus treated PET fabric formed the apatite uniformly on surfaces of individual fibers constituting the
fabric in SBF within 3 d. Two or three dimensional PET fabrics modified with the nano-sized brookite on surfaces of the individual
fibers constituting the fabric by the present method are believed to be useful as flexible bone substitutes, since they could
be integrated with living bone through the apatite formed on their constituent fibers. 相似文献
117.
Takahiro Wada Yuichiro Manabe Issei Nakamura Yuichi Tsunoyama Hiroo Nakajima Masako Bando 《Journal of Nuclear Science and Technology》2016,53(11):1824-1830
We have investigated the dependence of the mutation frequency on the dose and dose rate of artificial radiation using the Whack-A-Mole (WAM) model that we recently proposed. In particular, we pay special attention to the case of long-term and low-dose-rate exposure. Our results indicate that the WAM model successfully describes the dose-rate dependence, and it can replace the so-called dose and dose-rate effectiveness factor (DDREF), which has been used for long, to account for the differences between high-dose-rate and low-dose-rate data. The basic properties of the WAM model are discussed with special emphasis on the dose-rate dependence in order to demonstrate how the dose-rate dependence, which is built into the model explicitly, plays a key role. Biological effects of long-term exposure to extremely low-dose-rate radiation are discussed in light of analysis of mega-mouse experiments using the WAM model. In the WAM model, the effects of long-term exposure show a saturation property, thus making it distinctly different from the ‘linear no threshold (LNT)’ hypothesis that predicts a linear increase of the effects with time. 相似文献
118.
Hiranaga Y Uda T Kurihashi Y Tanaka K Cho Y 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(12):2523-2528
In this study, several read/write tests were conducted using a novel ferroelectric data storage test system equipped with a spindle motor, targeted at high-speed data transfer using a single probe head. A periodically inverted signal can be read out correctly with a bit rate of 100 kbps using this test system, and 10 Mbps data transfer is also possible during writing operations. The effect of a dc-offset voltage applied to the writing waveform with high-speed probe scanning is discussed. In addition, a novel noncontact probe height control technique was adopted to solve the problem of tip abrasion. 相似文献
119.
Murakami K Hara H Masuda Y Ohigashi H Irie K 《Chembiochem : a European journal of chemical biology》2007,8(18):2308-2314
The neurotoxicity of the 42-mer and 40-mer amyloid beta peptides (Abeta42 and Abeta40) is closely related to the radicalization at both Tyr10 and Met35. Abeta42 is more neurotoxic than Abeta40. Our previous structural analyses of Abeta42 suggested that Tyr10 and Met35 are brought closer together by the turn at positions 22 and 23, and the S-oxidized radical cation at position 35, which is the ultimate toxic radical species, can be produced effectively through oxidation by the phenoxy radical at position 10. To verify this idea, their separation was measured by site-directed spin labeling (MTSSL) by using ESR spectroscopy. Among the three kinds of Abeta42 derivatives, which are doubly or singly spin-labeled at position 10 and 35, only 10,35-MTSSL-Abeta42 showed a clear dipole coupling in continuous-wave ESR; this suggests that the intramolecular spin labels at position 10 and 35 in Abeta42 are located within approximately 15 A. In contrast, 10,35-MTSSL-Abeta40 did not give such signals. The distance between Tyr10 and Met35 in 10,35-MTSSL-Abeta40, which was successfully measured by pulsed ESR spectroscopy was 30 A long. The difference in the distance between Abeta42 and Abeta40 could explain in part the stronger neurotoxicity of Abeta42 compared to Abeta40. 相似文献
120.
Yuichi Miura Toru Ando Naoki Matsushima Takayoshi Mamiya 《Journal of Low Temperature Physics》1999,115(5-6):219-227
Pressure measurements have been made in a hcp solid
3
He at molar volumes from 18.90 to 19.45 cm
3
/mol, at temperatures down to 1 mK and in magnetic fields up to 0.16 Tesla. The results are analyzed by a high-temperature series expansion with multiple-exchange processes. The molar volume dependence of the multiple-exchange interactions has been determined by pressure measurements in magnetic fields. The results indicate that the exchange frequencies determined by the pressure measurements in a hcp solid
3
He are consistent with those obtained by magnetization measurements. 相似文献