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111.
Utilizing a nano‐sorbent for the selective solid‐phase extraction of vanillic acid prior to its determination by photoluminescence spectroscopy 下载免费PDF全文
Hossein Abdolmohammad‐Zadeh Fatemeh Mahmoudi‐kordi Manoochehr Rahmati 《Luminescence》2014,29(8):1162-1168
Vanillic acid (VA) is a phenolic acid, and acts as a natural antioxidant in fruits, vegetables and plants. The extraction and determination of trace levels of VA in plants is important, because stimulation of protein synthesis and activation of antioxidant enzymes occur in the presence of phenolic acids at trace levels. In this research, a photoluminescence spectroscopic method was developed for the quantification of VA in plant samples after separation and pre‐concentration. Selective extraction of VA from aqueous solution was performed using a solid‐phase extraction column packed with nickel–aluminum layered double hydroxide as a nano‐sorbent. After elution of extracted analyte from the column using 3 mL of a 3 mol/L NaOH solution, its concentration was determined spectrofluorometrically at λem = 357 nm with excitation at λex = 280 nm. The spectrofluorometry method gave a linear response for VA within the range 20.0–900.0 µg/L, with a correlation coefficient of 0.9982. The limit of detection and sorption capacity were 7.6 µg/L and 66.2 mg/g, respectively. The method was validated by comparing the obtained results with gas chromatographic data. This method was used to determine VA in Chenopodium album and Prangos asperula plants. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
112.
Echegaray Eleonora Rabi Sandra Cárdenas Carlos Zadeh Farnaz Heidar Rabi Nataly Lee Sungmin Anderson James S. M. Toro-Labbe Alejandro Ayers Paul W. 《Journal of molecular modeling》2014,20(3):1-7
Journal of Molecular Modeling - A new 3D graphical representation of DNA sequences is introduced. This representation is called 3D-dynamic representation. It is a generalization of the 2D-dynamic... 相似文献
113.
Omid Sayar Hamid Reza Lotfi Zadeh Zhad Omid Sadeghi Vahid Amani Ezzatolla Najafi Najmeh Tavassoli 《Biological trace element research》2012,150(1-3):403-410
We have developed a facile and highly sensitive sorbent for cadmium and lead ions. It is based on Fe3O4 nanoparticles functionalized with a derivative of picoline and was characterized by scanning electron microscopy, differential thermographic analysis, and elemental analysis. The material can be applied to the preconcentration of lead and cadmium ions. Factors such as the type, concentration and volume of eluent, the pH of the sample solution, the time for extraction, and the volume of the sample were studied. The effects of a variety of ions on preconcentration and recovery of these ions were also investigated. The ions were determined by FAAS, and the limits of detection are <0.8 and <0.061???g?L?1 for lead and cadmium, respectively. Recoveries and precisions are >98.0?% and <1.3?%, respectively. The method was validated by analyzing several certified leaf reference materials. 相似文献
114.
J. Rostam Zadeh L. I. Penkov E. A. Klimov E. S. Platonov G. E. Sulimova 《Russian Journal of Genetics》2005,41(10):1139-1143
Imprinted genes play important roles in the mammalian development. In the parthenogenetic embryos (PE), there is only expression of maternally expressed genes. Therefore, PEs are appropriate experimental models to study genomic imprinting controlling mechanisms. The maternally expressed H19 and paternally expressed Igf2 are reciprocally imprinted genes in normal embryos. Here, we studied effect of transforming growth factor alpha (TGFα) treatment in vitro (10 ng/ml at the morula stage) on the expression of Igf2/H19 locus in mice PE (9.5 days of gestation, 25 somites) and their placentas (PP). Using RT-PCR, we showed that TGFα reactivated maternally imprinted Igf2 gene in parthenogenetic embryos and placentas. In spite of similar Tgfα expression in the preimplantation stages, its expression in the 9.5-day parthenogenetic embryos is significantly less than in normal embryos (NE). In our experiments, it was shown that reactivation of Igf2 gene occurred independently of H19 gene. In vitro TGFα treatment of mouse PE reactivated paternally expressed Igf2 gene in the PE and PP. In the PE and PP, both Igf2 and H19 were expressed. It seems that TGFα can play an important role as modulator of the Igf2/H19 locus. 相似文献
115.
F. Rakhshandehroo R. Pourrahim H. Zamani Zadeh S. Rezaee M. Mohammadi 《Journal of Phytopathology》2005,153(7-8):480-484