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Januário AH Lourenço MV Domézio LA Pietro RC Castilho MS Tomazela DM da Silva MF Vieira PC Fernandes JB França Sde C 《Chemical & pharmaceutical bulletin》2005,53(7):740-742
Crude extracts of callus and roots of Dipteryx odorata were analyzed by HPLC to detect and quantify isoflavone contents. Based on spectroscopic and X-ray crystallography data the structures of two isoflavones were elucidated as 7-hydroxy-4',6-dimethoxyisoflavone and 3',7-dihydroxy-4',6-dimethoxyisoflavone. The production of dry biomass of 7-hydroxy-4',6-dimethoxyisoflavone in cultured callus was 4.12 mg/g, approximately eleven fold higher than the amount accumulated in roots of D. odorata wild-growing plants. The 7-hydroxy-4',6-dimethoxyisoflavone was effective against glyceraldehyde-3-phosphate dehydrogenase from Trypanosoma cruzi. This is the first report on those bioactive isoflavones accumulated in callus of D. odorata. 相似文献
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Natália Goedtel Medeiros Vanessa Cezar Ribas Vladimir Lavayen Jacqueline Arguello Da Silva 《Journal of Solid State Electrochemistry》2016,20(9):2419-2426
Flower-like CuO hierarchical nanostructures were synthesized on copper foil substrate through a simple wet chemical route in alkaline media at room temperature. SEM images collected at different reaction times revealed the transformation of initially formed Cu(OH)2 nanowires to flower-like CuO nanostructures. The hierarchical structure of the as-prepared CuO showed high electrocatalytic activity towards the oxidation of glucose making it a promising electrode material for the development of non-enzymatic glucose sensor. The amperometric sensor exhibited a wide linear response to glucose ranging from 4.5 × 10?5 to 1.3 × 10?3 mol L?1 (R 2 = 0.99317) at fixed potential of 0.3 V. The detection limit was 6.9 × 10?6 mol L?1 (LOD = 3σ/s) with a sensitivity of 1.71 μA μmol?1 cm?2. Moreover, the developed sensor offers a fast amperometric response, good selectivity and stability. 相似文献
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Jan Kuliga Rodrigo Cezar de Campos Ferreirra Rajan Adhikari Stephen Massicot Dr. Michael Lepper Helen Hölzel Prof. Dr. Norbert Jux Dr. Hubertus Marbach Prof. Dr. Abner de Siervo Prof. Dr. Hans-Peter Steinrück 《Chemphyschem》2021,22(4):396-403
We study the interaction and metalation reaction of a free base 5,10,15,20-terakis(4-cyanophenyl)porphyrin (2HTCNPP) with post-deposited Zn atoms and the targeted reaction product Zn-5,10,15,20-terakis(4-cyanophenyl)porphyrin (ZnTCNPP) on a Ag(111) surface. The investigations are performed with scanning tunneling microscopy at room temperature after Zn deposition and subsequent heating. The goal is to obtain further insights in the metalation reaction and the influence of the cyanogroups on this reaction. The interaction of 2HTCNPP with post-deposited Zn leads to the formation of three different 2D ordered island types that coexist on the surface. All contain a new species with a bright appearance, which increases with the amount of post-deposited Zn. We attribute this to metastable SAT (“sitting atop”) complexes formed by Zn and the macrocycle, that is, an intermediate in the metalation reaction to ZnTCNPP, which occurs upon heating to 500 K. Interestingly, the activation barrier for the successive reaction of the SAT complex to the metalated ZnTCNPP species can also be overcome by a voltage pulse applied to the STM tip. 相似文献
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Salluzzo M Ghiringhelli G Cezar JC Brookes NB De Luca GM Fracassi F Vaglio R 《Physical review letters》2008,100(5):056810
The mechanism of field-effect doping in the 123 high critical temperature superconductors (HTS) has been investigated by x-ray absorption spectroscopy in the presence of an electric field. We demonstrate that holes are created at the CuO chains of the charge reservoir and that field-effect doping of the CuO(2) planes occurs by charge transfer, from the chains to the planes, of a fraction of the overall induced holes. The electronic properties of the charge reservoir and of the dielectric-HTS interface determine the electric field doping of the CuO(2) planes. 相似文献
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M. Opel K. -W. Nielsen S. Bauer S. T. B. Goennenwein J. C. Cezar D. Schmeisser J. Simon W. Mader R. Gross 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):437-444
The existence of semiconductors exhibiting long-range ferromagnetic ordering at room temperature still is controversial. One
particularly important issue is the presence of secondary magnetic phases such as clusters, segregations, etc. These are often
tedious to detect, leading to contradictory interpretations. We show that in our cobalt doped ZnO films grown homoepitaxially
on single crystalline ZnO substrates the magnetism unambiguously stems from metallic cobalt nano-inclusions. The magnetic
behavior was investigated by SQUID magnetometry, X-ray magnetic circular dichroism, and AC susceptibility measurements. The
results were correlated to a detailed microstructural analysis based on high resolution X-ray diffraction, transmission electron
microscopy, and electron-spectroscopic imaging. No evidence for carrier mediated ferromagnetic exchange between diluted cobalt
moments was found. In contrast, the combined data provide clear evidence that the observed room temperature ferromagnetic-like
behavior originates from nanometer sized superparamagnetic metallic cobalt precipitates. 相似文献