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31.
Astulla A Hirasawa Y Rahman A Kusumawati I Ekasari W Widyawaruyanti A Zaini NC Morita H 《Natural product communications》2011,6(3):323-326
Two new acyclic diterpenes, melidianolic acids A (1) and B (2), have been isolated from the bark of Aphanamixis grandifolia. Their structures were elucidated on the basis of spectroscopic and chemical methods. Melidianolic acids A (1) and B (2) showed antimalarial activity against Plasmodium falciparum 3D7 with IC50 of 6.1 and 7.3 microg/mL, respectively. 相似文献
32.
Takafumi Seto Kenji Koga Hiroyuki Akinaga Fumiyoshi Takano Takaaki Orii Makoto Hirasawa 《Journal of nanoparticle research》2006,8(3-4):371-378
Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co–Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism. 相似文献
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Takahide Y Konoike T Enomoto K Nishimura M Terashima T Uji S Yamamoto HM 《Physical review letters》2006,96(13):136602
The current-voltage characteristics of layered organic crystals theta-(BEDT-TTF)2MZn(SCN)4 (M = Cs, Rb) follow the power law with a large exponent (e.g., 8.4 at 0.29 K for M = Cs) over a wide range of currents in the low-temperature insulating state. The power-law characteristics are attributed to electric field-induced unbinding of electron-hole pairs that are thermally excited in the background of the two-dimensional charge order. The magnitude of crossover electric fields from Ohmic to the power-law characteristics indicates that the electron-electron Coulomb interaction is significantly long-ranged: The screening length is greater than 10 molecule sites. 相似文献
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37.
Kazuaki Kuwata Masashi SuzukiYoshikazu Inami Kengo HanayaTakeshi Sugai Mitsuru Shoji 《Tetrahedron letters》2014
A stereoselective synthesis of scyphostatin hydrophilic moiety was accomplished. Substrate- and reagent-controlled dihydroxylation of tri- and monosubstituted alkenes afforded desired diols, respectively. Chemo- and stereoselective allylation of α-(methoxycarbonyl)cyclohexanone provided allylcyclohexanol. Oxidative cleavage of glycol and subsequent β-elimination of siloxycyclohexanone furnished the desired epoxycyclohexenone. 相似文献
38.
Optical Review - This paper proposes a novel steganography method to show an aerial image that is formed with aerial imaging by retro-reflection by use of dual transparent balls made of acrylic... 相似文献
39.
Shinpei Okawa Takeshi Hirasawa Ryota Sato Toshihiro Kushibiki Miya Ishihara Toshiharu Teranishi 《Optical Review》2018,25(3):365-374
Gold nanoparticles (AuNPs) are used as a contrast agent of the photoacoustic (PA) imaging. The efficiency of AuNPs has been discussed with the absorption cross section. However, the effects of the scattering of the light by AuNPs and surrounding medium on the PA signal from AuNPs have not been discussed. The PA signals from the aqueous solution of AuNPs were examined in the numerical simulation and the experiment. In the numerical simulation, the absorption and scattering cross sections of spherical and polyhedral AuNPs were calculated by Mie theory and discrete dipole approximation. Monte Carlo simulation calculated the absorbed light energy in the aqueous solution of AuNPs. Based on the PA wave equation, the PA signals were simulated. In the experiment, the PA signal from the aqueous solution of AuNP was measured by use of a piezoelectric film and a Q-switched Nd:YAG laser operated at 532 nm. The results of the numerical simulation and the experiment agreed well. In the numerical simulation and the experiment, a single Au nanocube with 50-nm edge generated the peak value of the PA signal significantly. It was approximately 350 times and twice as large as the peak values of the spherical AuNPs with 10- and 50-nm diameters, respectively. The peak value of the PA signal depended on both the absorption and scattering coefficients of the AuNPs and the surrounding medium. The peak value increased with the scattering coefficient in a quadratic manner. The character of the temporal profile of the PA signal such as full width at half maximum depended on the scattering coefficient of the AuNPs. 相似文献
40.
Utilization of biocatalysts with high accessibility and availability, which have recently been applied in the preparation of enantiomerically enriched starting materials and synthetic intermediates for natural product syntheses (mainly 2013–2017) are summarized in this review. The main contents are as follows: 1) recruitment of biocatalysts for the transformation of organic compounds; 2) special precautions for preparative-scale biocatalytic synthetic experiments; 3) asymmetric reduction of carbonyl substrates; 4) kinetic resolution of alcohol and carboxylate enantiomers; 5) desymmetrization of multifunctional alcohol and carboxylate substrates; and 6) recognition of remote and non-central chirality. 相似文献