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761.
Visible quantum cutting has been observed in GdPO4:Tb3+ upon Tb3+ 4f8–4f75d1 excitation and host excitation, and in Sr3Gd(PO4)3:Tb3+ upon Tb3+ 4f8–4f75d1 excitation. In the quantum cutting process, Tb3+ acts as a quantum cutter, which converts one short wavelength ultraviolet photon or one vacuum ultraviolet photon into more than one visible photon. The quantum cutting involves a cross-relaxation process between two neighboring Tb3+ and direct energy transfer between Tb3+ and Tb3+ or Tb3+ and Gd3+, depending on the excitation wavelength. The quantum efficiency variation of GdPO4:xTb3+ and Sr3Gd(PO4)3:xTb3+ shows a growing trend with increasing of Tb3+ content from x=1.5% to 13%. 相似文献
762.
Yoshinori Yonesaki Takahiro Takei Nobuhiro Kumada Nobukazu Kinomura 《Journal of solid state chemistry》2009,182(3):547-554
Emission properties of Eu2+-doped M3MgSi2O8 (M: Ba, Sr, Ca) are discussed in terms of the crystal structure. When Ba2+ ions account for over one third of M2+ ions, M3MgSi2O8 crystallizes in glaserite-type trigonal structure, while Ba-free compounds crystallize in merwinite-type monoclinic structure. Under UV excitation, the Eu2+-doped glaserite-type compounds exhibit an intense blue emission assigned to 5d-4f electron transition at about 435 nm, regardless of the molar ratio of Ba2+, Sr2+ and Ca2+ ions. By contrast, the Eu2+-doped merwinite-type compounds show an emission color sensitive to the ratio. A detailed analysis of the emission spectra reveals that the emission chromaticity for the Eu2+-doped M3MgSi2O8 is composed of two emission peaks reflecting two different sites accommodating M2+ ion. 相似文献
763.
Masaaki Kobayashi Nobuhiro Sugihara Hirohiko Ise Takeshi Omasa Naoki Negishi 《先进技术聚合物》2004,15(5):232-243
Cytochrome P‐450s (CYPs) are important biopolymers for the maintenance of cellular function. If metabolic activity of the CYP in the cells can be estimated, so can the function of metabolism, which is closer to the organism. In this research, the method of measuring the drug metabolic activity inside the cell by making use of an electrochemical technique was examined. Human hepatoma GS‐3A4‐HepG2 cells of which the cytochrome P‐4503A4 (CYP3A4) drug metabolic activity is found to be the same as that of primary hepatocytes were used in the experiment. The GS‐3A4‐HepG2 cells were cultured on an indium‐tin oxide (ITO) electrode until they became confluent. Substrate testosterone and inhibitor ketoconazole of CYP3A4 were exposed to cells cultured on an ITO electrode, and the reaction was observed by noting the electrochemical impedance measurement. Impedance was decomposed into the resistance component and the reactance component, and each was examined in detail. As a result, according to testosterone concentration change, there was a remarkable time change in the reactance component. A similar impedance measurement was done by using human hepatoma HepG2 cells in which the drug metabolic activity had extremely decreased. Nevertheless, no time change in the reactance component that was noticed in GS‐3A4‐HepG2 cells was observed. Next, the amount of metabolite in the solution after impedance measurement was measured by means of liquid chromatography‐tandem mass spectroscopy (LC‐MS/MS). In the experiment with GS‐3A4‐HepG2 cells, a testosterone concentration‐dependent correlation was observed between the reactance component change and the amount of metabolite. But, in the impedance measurement by ketoconazole, the change in reactance components was not observed in either the GS‐3A4‐HepG2 cells or the HepG2 cells. Ketoconazole and the heme iron in CYP3A4 effect the coordination bond, but ketoconazole was not metabolized by CYP3A4. It was confirmed that the time change in the reactance component which was caused by the testosterone was detected neither in the cells that take up the substrate, nor in the coordination bond between the CYP enzyme and the drug. Therefore, the time change in the remarkable reactance component observed by this electrochemical impedance measurement is dependent on drug metabolic activity. An electrochemical drug metabolic activity measuring method with the human hepatoma GS‐3A4‐HepG2 cells was able to be established. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
764.
Partial Charge Transfer in the Shortest Possible Metallofullerene Peapod,La@C82⊂[11]Cycloparaphenylene 下载免费PDF全文
Takahiro Iwamoto Dr. Zdenek Slanina Dr. Naomi Mizorogi Dr. Jingdong Guo Prof. Dr. Takeshi Akasaka Shigeru Nagase Dr. Hikaru Takaya Dr. Nobuhiro Yasuda Prof. Dr. Tatsuhisa Kato Prof. Dr. Shigeru Yamago 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14403-14409
[11]Cycloparaphenylene ([11]CPP) selectively encapsulates La@C82 to form the shortest possible metallofullerene–carbon nanotube (CNT) peapod, La@C82?[11]CPP, in solution and in the solid state. Complexation in solution was affected by the polarity of the solvent and was 16 times stronger in the polar solvent nitrobenzene than in the nonpolar solvent 1,2‐dichlorobenzene. Electrochemical analysis revealed that the redox potentials of La@C82 were negatively shifted upon complexation from free La@C82. Furthermore, the shifts in the redox potentials increased with polarity of the solvent. These results are consistent with formation of a polar complex, (La@C82)δ??[11]CPPδ+, by partial electron transfer from [11]CPP to La@C82. This is the first observation of such an electronic interaction between a fullerene pea and CPP pod. Theoretical calculations also supported partial charge transfer (0.07) from [11]CPP to La@C82. The structure of the complex was unambiguously determined by X‐ray crystallographic analysis, which showed the La atom inside the C82 near the periphery of the [11]CPP. The dipole moment of La@C82 was projected toward the CPP pea, nearly perpendicular to the CPP axis. The position of the La atom and the direction of the dipole moment in La@C82?[11]CPP were significantly different from those observed in La@C82?CNT, thus indicating a difference in orientation of the fullerene peas between fullerene–CPP and fullerene–CNT peapods. These results highlight the importance of pea–pea interactions in determining the orientation of the metallofullerene in metallofullerene–CNT peapods. 相似文献
765.
Takahiro Hayasaka Naoko Goto-Inoue Nobuhiro Zaima Kamlesh Shrivas Yukiyasu Kashiwagi Mari Yamamoto Masami Nakamoto Mitsutoshi Setou 《Journal of the American Society for Mass Spectrometry》2010,21(8):1446-1454
A new approach to the visualization of fatty acids in mouse liver and retinal samples has been developed using silver nanoparticles
(AgNPs) in nanoparticle-assisted laser desorption/ ionization imaging mass spectrometry (nano-PALDI-IMS) in negative ion mode.
So far, IMS analysis has concentrated on main cell components, such as cell membrane phospholipids and cytoskeletal peptides.
AgNPs modified with alkylcarboxylate and alkylamine were used for nano-PALDI-IMS to identify fatty acids, such as stearic,
oleic, linoleic, arachidonic, and eicosapentaenoic acids, as well as palmitic acid, in mouse liver sections; these fatty acids
are not detected using 2,5-dihydroxybenzoic acid (DHB) as a matrix. The limit of detection for the determination of palmitic
acid was 50 pmol using nano-PALDI-IMS. The nano-PALDI-IMS method is successfully applied to the reconstruction of the ion
images of fatty acids in mouse liver sections. We verified the detection of fatty acids in liver tissue sections of mice by
analyzing standard lipid samples, which showed that fatty acids were from free fatty acids and dissociated fatty acids from
lipids when irradiated with a laser. Additionally, we applied the proposed method to the identification of fatty acids in
mouse retinal tissue sections, which enabled us to learn the six-zonal distribution of fatty acids in different layers of
the retina. We believe that the current approach using AgNPs in nano-PALDI-IMS could lead to a new strategy to analyze basic
biological mechanisms and several diseases through the distribution of fatty acids. 相似文献
766.
Prof. Dr. Masayuki Endo Seigi Yamamoto Tomoko Emura Kumi Hidaka Dr. Nobuhiro Morone Prof. Dr. John E. Heuser Prof. Dr. Hiroshi Sugiyama 《Angewandte Chemie (International ed. in English)》2014,53(29):7484-7490
We developed a novel method to design various helical tubular structures using the DNA origami method. The size‐controlled tubular structures which have 192, 256, and 320 base pairs for one turn of the tube were designed and prepared. We observed the formation of the expected short tubes and unexpected long ones. Detailed analyses of the surface patterns of the tubes showed that the short tubes had mainly a left‐handed helical structure. The long tubes mainly formed a right‐handed helical structure and extended to the directions of the double helical axes as structural isomers of the short tubes. The folding pathways of the tubes were estimated by analyzing the proportions of short and long tubes obtained at different annealing conditions. Depending on the number of base pairs involved in one turn of the tube, the population of left‐/right‐handed and short/long tubes changed. The bending stress caused by the stiffness of the bundled double helices and the non‐natural helical pitch determine the structural variety of the tubes. 相似文献
767.
Miyoko Kamigauchi Yuko Miyamoto Kinuko Iwasa Makiko Sugiura Zjujiro Nishijo Narao Takao Toshimasa Ishida Yasuko In Masatoshi Inoue 《Helvetica chimica acta》1990,73(8):2171-2178
The solid-state and solution conformations of (+)-chelidonine ( 1 ), a biologically active alkaloid, were determined by X-ray diffraction and 1H-NMR spectroscopy, X-Ray diffraction analysis revealed a conformer with B/C ‘anti-type’ cis conjunction, a half-chair of ring B , and a twist half-chair of ring C. One H2O molecule per one alkaloid molecule was cocrystallized and stabilized by H-bonding with OH? C(11). Analysis of the thermal behavior of the crystal showed more thermal stability in the monohydrate than the anhydrate. The NMR measurement of concentration and temperature dependences in CDCl3 and in (CD3)2SO suggested that the OH group of 1 was intramolecularly H -bonded to N(5) in (CD3)2SO and intermolecularly H-bonded to the solvent in CDCl3. Conformational-energy calculations by the MNDO method showed that the intramolecular H -bond was little affected by the conformational stabilization of 1 . 相似文献
768.
Katsumata K Ohno Y Tomita K Sakai M Nakajima A Kakihana M Fujishima A Matsushita N Okada K 《Photochemistry and photobiology》2011,87(5):988-994
Titanium dioxide thin films were prepared by using four water-soluble titanium complexes of titanium-lactate, tartalate, malate and salicylate complex solutions. The crystalline phases detected in the films were anatase. The surface microstructures of the four film samples were different in their grain sizes. Photocatalytic decomposition activity of the four films was almost the same, but their photoinduced hydrophilicities were different. The film prepared using titanium-salicylate complex exhibited lower hydrophilic conversion rate than the other films. Grain size and stress yielded to the film are considered to be important factors on the photoinduced hydrophilicity. 相似文献
769.
Prof. Nobuhiro Yanai Prof. Nobuo Kimizuka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10336-10348
The addition of stimuli-responsiveness to anti-Stokes emission provides a unique platform for biosensing and chemosensing. Particularly, stimuli-responsive photon upconversion based on triplet–triplet annihilation (TTA-UC) is promising due to its occurrence at low excitation intensity with high efficiency. This Minireview summarizes the recent developments of TTA-UC switching by external stimuli such as temperature, oxygen, chemicals, light, electric field, and mechanical force. For the systematic understanding of the underlying general mechanisms, the switching mechanisms are categorized into four types: 1) aggregation-induced UC; 2) assembly-induced air-stable UC; 3) diffusion-controlled UC; and 4) energy-transfer-controlled UC. The development of stimuli-responsive smart TTA-UC systems would enable sensing with unprecedented sensitivity and selectivity, and expand the scope of TTA-UC photochemistry by combination with supramolecular chemistry, materials chemistry, mechanochemistry, and biochemistry. 相似文献
770.
Hajime Kobori Atsushi Sekiya Nobuhiro Yasuda Keiichi Noguchi Tomohiro Suzuki Jae-Hoon Choi Hirofumi Hirai Hirokazu Kawagishi 《Tetrahedron letters》2013
Three novel compounds were isolated from the culture broth of Armillaria sp. Their structures were elucidated mainly by spectroscopic data analyses. All the compounds regulated hypocotyl and root growth of lettuce. 相似文献