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151.
Boligon AA Sagrillo MR Machado LF de Souza Filho O Machado MM da Cruz IB Athayde ML 《Molecules (Basel, Switzerland)》2012,17(5):5757-5769
Flavonoids are claimed to protect against cardiovascular disease, certain forms of cancer and ageing, possibly by preventing initial DNA damage. Therefore, we investigated the protective effects of crude extract, ethyl acetate fraction and flavonoids (quercetin, quercitrin, isoquercitrin and rutin) isolated from the leaves from Scutia buxifolia against chromosome damage induced by H?O? in human lymphocytes by analyzing cellular growth rate, cell viability, mitotic index and chromosomal instability. We found a differential response among the compounds tested, with the ethyl acetate fraction being more effective than the crude extract, a difference perhaps related to the presence of the antioxidants identified and quantified by HPLC/DAD. In general, quercetin, isoquercitrin and rutin recovered the mitotic index and chromosomal instability more than quercitrin after treatment with hydrogen peroxide. 相似文献
152.
Rodríguez-Cea A Linde Arias AR Fernández de la Campa MR Costa Moreira J Sanz-Medel A 《Talanta》2006,69(4):963-969
Metal speciation analysis in MTs was carried out in two tropical fish species of Brazil, the freshwater fish pearl cichlid (Geophagus brasiliensis) and the marine fish white sea catfish (Netuma barba), that are presently used to monitor the effects of heavy metal pollution in aquatic ecosystems in Brazil. In order to obtain the MT fraction, liver cytosols from both fish species where subjected to size exclusion fractionation, monitoring on-line the metal signal (Cd, Cu and Zn) by ICP-MS while protein elution was followed by on-line UV detection. That MT fraction was then separated by anion-exchange (AE)-FPLC, whose optimal chromatographic conditions were optimized for the separation of the different hepatic MT isoforms existing in both fish species. Specific detection of separated metalloforms was carried out again by the hyphenation of the AE chromatographic system with the ICP-MS instrument. The analytical results showed that MTs of these fish species, unknown so far, exhibited unique characteristics in comparison with standard MTs and other fish liver MTs. In fact, MT isoforms of N. barba turned out to be very anionic, as indicated by their high retention in the Mono Q column and the strong ionic strength required to separate them. As for G. brasiliensis, cadmium was exclusively present in only one of the peaks of the MT isoforms showing a unique metal-binding behavior for MT in this fish species. The differences between the MTs among these species and the different association of metals in particular MT isoforms display the importance of the metal speciation analysis in these proteins prior to its use as bioindicators. 相似文献
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154.
Sebastian van de Linde Sarah Aufmkolk Christian Franke Thorge Holm Teresa Klein Anna Löschberger Sven Proppert Steve Wolter Markus Sauer 《Chemistry & biology》2013,20(1):8-18
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155.
Tobias F. Pascher Dr. Milan Ončák Dr. Christian van der Linde Prof. Dr. Martin K. Beyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8286-8295
The electronic structure and photochemistry of copper formate clusters, CuI2(HCO2)3− and CuIIn(HCO2)2n+1−, n≤8, are investigated in the gas phase by using UV/Vis spectroscopy in combination with quantum chemical calculations. A clear difference in the spectra of clusters with CuI and CuII copper ions is observed. For the CuI species, transitions between copper d and s/p orbitals are recorded. For stoichiometric CuII formate clusters, the spectra are dominated by copper d–d transitions and charge-transfer excitations from formate to the vacant copper d orbital. Calculations reveal the existence of several energetically low-lying isomers, and the energetic position of the electronic transitions depends strongly on the specific isomer. The oxidation state of the copper centers governs the photochemistry. In CuII(HCO2)3−, fast internal conversion into the electronic ground state is observed, leading to statistical dissociation; for charge-transfer excitations, specific excited-state reaction channels are observed in addition, such as formyloxyl radical loss. In CuI2(HCO2)3−, the system relaxes to a local minimum on an excited-state potential-energy surface and might undergo fluorescence or reach a conical intersection to the ground state; in both cases, this provides substantial energy for statistical decomposition. Alternatively, a CuII(HCO2)3Cu0− biradical structure is formed in the excited state, which gives rise to the photochemical loss of a neutral copper atom. 相似文献
156.
U. Shymanovich M. Nicoul J. Blums K. Sokolowski-Tinten A. Tarasevitch T. Wietler M. Horn von Hoegen D. von der Linde 《Applied Physics A: Materials Science & Processing》2007,87(1):7-11
Following femtosecond laser excitation, large transient changes in the X-raydiffraction efficiency have been observed in thin
crystalline films of germanium. This behavior is explained in terms of the thermo-acoustic response of the impulsively heated
material, when an inhomogeneously strained surface layer is probed by divergent X-ray beams.
PACS 61.10.Nz; 41.50.+h 相似文献
157.
Auke Snijder Bert Klumperman Rob Van Der Linde 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2350-2359
The introduction of a functional group into a poly(butyl acrylate) polymer prepared by copper‐mediated atom transfer radical polymerization and the characterization of the prepared polymer by gradient polymer elution chromatography are reported. The bromo end group of the initial polymer can be transformed into a different functional group with several functionalization reactions, including nucleophilic substitution and atom transfer radical addition (ATRA), in combination with comonomers, addition–fragmentation transfer agents, or stable radicals. Several new functionalization agents are reported, including ATRA using 1‐(3‐hydroxymethyl‐phenyl)‐pyrrole‐2,5‐dione and trimethyl{1‐[4‐(2‐trimethylsiloxyethoxy)]phenylethenyloxy}silane and nucleophilic substitution using 2‐mercapto ethanol. The rate constant of the functionalization reaction and the final functionality are determined with gradient polymer elution chromatography, a technique by which qualitative and quantitative information about the conversion can be obtained. Polymers with a functionality greater than 95% are reported. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2350–2359, 2002 相似文献
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160.
Theoretical studies predict that [Al·nH(2)O](+) clusters are present as hydride-hydroxide species HAlOH(+)(H(2)O)(n-1) in gas-phase experiments, energetically favoured by 200 kJ mol(-1) over Al(+)(H(2)O)(n). After collisions with D(2)O, however, no H/D scrambling occurs between H(2)O and D(2)O in clusters with n > 38, indicating that large clusters are present as the higher-energy isomers Al(+)(H(2)O)(n). 相似文献