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151.
Novel pyridino-α-pyrone sesquiterpene type pileotin produced by a sea urchin-derived Aspergillus sp.
Mayumi KitanoTakeshi Yamada Taro AmagataKatsuhiko Minoura Reiko TanakaAtsushi Numata 《Tetrahedron letters》2012,53(32):4192-4194
A new metabolite, pileotin A, was isolated from a strain of Aspergillus fumigatus originally obtained from the sea urchin Toxopneustes pileolus together with the known compound oxalicine B. The relative stereostructure of pileotin A was elucidated based on spectroscopic analyses, including 1D and 2D NMR techniques. This unique pyridino-α-pyrone sesquiterpene type metabolite has spiro-δ-lactone at C-4. 相似文献
152.
Aki Hayashi Hirokazu Nakayama Taro Eguchi Nobuo Nakamura Mitsutomo Tsuhako 《Molecular Crystals and Liquid Crystals》2013,570(2):573-578
Abstract Two kinds of diethylenetriamine (2E3A) intercalation compounds of α-zirconium phosphate with different interlayer distances could be obtained by regulating the reaction time and temperature. Phase I (d = 10.2 Å) slowly transforms to Phase II(d = 15. 8 Å) with transformation enthalpy of 30 kJ-mol?1 in 2E3A aqueous solution. The conformation of 2E3A in Phase I and Phase II were confirmed to be bent and all trans (straight) forms by31P MAS NMR and XRD measurements. Two phases have different adsorption behavior for gaseous carboxylic acids. Phase II can adsorb considerable amount of carboxylic acids whereas Phase I adsorb a little. 相似文献
153.
The dual nature of geometry, in that it is a theoretical domain and an area of practical experience, presents mathematics teachers with opportunities and dilemmas. Opportunities exist to link theory with the everyday knowledge of pupils but the dilemmas are that learners very often find the dual nature of geometry a chasm that is very difficult to bridge. With research continuing to focus on understanding the nature of this problem, with a view to developing better pedagogical techniques, this paper examines the place of experimental tasks in the process of learning geometry. In particular, the paper provides some results from an analysis of innovative geometry textbooks designed in the early part of the 20th Century, a time when significant efforts were being made to improve the teaching and learning of geometry. The analysis suggests that experimental tasks have a vital role to play and that a potent tool for informing the design of such tasks, so that they build effectively on pupils' geometrical intuition, is the notion of the geometrical eye, a term coined by Charles Godfrey in 1910 as "the power of seeing geometrical properties detach themselves from a figure". 相似文献
154.
An expeditious route to furnish an isoquinoline skeleton via hydride shift mediated C-H bond functionalization was developed. In this process, an unusual [1,5]-H shift without the assistance of the adjacent heteroatom took place to produce tetrahydroisoquinoline derivatives in good to excellent chemical yields. The formal synthesis of (±)-tetrahydropalmatine was achieved by exploiting this new transformation. 相似文献
155.
Setsuo Mitsuda Taro Nakajima Motoyoshi Yamano Keiichirou Takahashi Hiroe Yamazaki Kazuya Masuda Yoshiaki Kaneko Noriki Terada Karel Prokes Klaus Kiefer 《Physica B: Condensed Matter》2009,404(17):2532-2534
Magnetic oxide CuFeO2 is a magnetoelectric multiferroic with new type of spin–polarization coupling different from that in the spin-current mechanism, where magnetic field-induced or nonmagnetic impurity-induced proper helical magnetic ordering generates a spontaneous electric polarization parallel to the helical axis. Using a CuFe1−xGaxO2 sample with x=0.035, in which the single ferroelectric phase is realized below TN8 K in zero magnetic field unlike CuFe1−xAlxO2, we have performed pyroelectric current, thermally stimulated current (TSC) and polarized neutron diffraction measurements to study a memory effect that the electric polarization is partially preserved even for 2nd-cooling from above TN without poling electric field. It was found that the charge trapped during 1st-cooling with poling electric field, which is released as TSC on heating, plays an important role in the memory effect. 相似文献
156.
Junko Fujimoto Sari Hayashi Hideyuki Kainuma Kazuhiro Manseki Taro Udagawa Hidekazu Miyaji 《化学:亚洲杂志》2019,14(15):2567-2572
Artificial antenna complexes of metal‐coordinated bis(8‐hydroxyquinoline)‐substituted porphyrin networks that mimic antenna chromophores in plants were organized on titanium dioxide electrodes in photoelectrochemical cells. The generated photocurrents can be optimized according to the two ways of porphyrin self‐assembly due to the “antenna effect”: changing the number of assembled porphyrin monolayers and the number of generations of the metal‐coordinated porphyrin networks. 相似文献
157.
We report the reduction of sidelobes in tight focusing patterns of radially higher-order Laguerre-Gaussian (LG) beams with nonhelical phase structures. Numerical calculations based on the vectorial Debye theory reveal that a class of annular masks reduces sidelobes in the tight focusing patterns only for radially even-order LG beams. The present scheme produces small focal spots beyond the diffraction limit suitable for application to scanning microscopy, laser fine processing, etc. 相似文献
158.
Kunio Atsumi Kiyoaki Katano Ken Nishihata Fumio Kai Eiichi Akita Taro Niida 《Tetrahedron letters》1982,23(29):2977-2980
Treatment of 7β-(2,2,3-trihaloalkylideneamino) cephalosporins with excess methanol in the presence of acid scavenger gave 7β-(2-haloalk-2-enylideneamino)-7α-methoxycephalosporins. 相似文献
159.
Norio Niiya Taro Arakawa Kunio Tada Fumiyuki Tadano Tatsuya Suzuki Joo-Hyong Noh Nobuo Haneji 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):507-513
We have analyzed the electrorefractive properties of a GaAs/AlGaAs modified five-layer asymmetric coupled quantum well (M-FACQW). The theoretical analyses show that the M-FACQW is expected to exhibit a giant negative electrorefractive index change Δn in the transparent-wavelength region away from the absorption edge. The influence of fluctuations in layer thickness on the electrorefractive properties of the M-FACQW was also investigated. Although the fluctuation in layer thickness deteriorates the characteristics of Δn in the M-FACQW, the M-FACQW still maintains a very giant Δn compared with that of a conventional rectangular quantum well without thickness fluctuation. In addition, we have fabricated the M-FACQW with monolayer accuracy by solid-source molecular beam epitaxy, and measured its photoabsorption current. The experimental results are in good agreement with the calculated properties. This indicates that the M-FACQW has great potential for use in ultra-wideband and low-voltage optical modulators and switches. 相似文献
160.
Feng Liu Junke Jiang Yaohong Zhang Chao Ding Taro Toyoda Shuzi Hayase Ruixiang Wang Shuxia Tao Qing Shen 《Angewandte Chemie (International ed. in English)》2020,59(22):8421-8424
Phase‐stable CsSnxPb1?xI3 perovskite quantum dots (QDs) hold great promise for optoelectronic applications owing to their strong response in the near‐infrared region. Unfortunately, optimal utilization of their potential is limited by the severe photoluminescence (PL) quenching, leading to extremely low quantum yields (QYs) of approximately 0.3 %. The ultra‐low sodium (Na) doping presented herein is found to be effective in improving PL QYs of these alloyed QDs without alerting their favourable electronic structure. X‐ray photoelectron spectroscopy (XPS) studies suggest the formation of a stronger chemical interaction between I? and Sn2+ ions upon Na doping, which potentially helps to stabilize Sn2+ and suppresses the formation of I vacancy defects. The optimized PL QY of the Na‐doped QDs reaches up to around 28 %, almost two orders of magnitude enhancement compared with the pristine one. 相似文献