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1.
A new Schiff base, N,N′-bis-(2-hydroxy-5-bromobenzyl)-2-hydroxy-1,3-diiminopropane, has been synthesized for the very sensitive
determination of iron(III) and iron(II) in natural water samples. It enabled a very selective and rapid method for iron determination
to be developed. The method has also been applied to total iron determination in sediment samples. In the preconcentration
system, the Schiff base reagent is mixed with the samples and chelates containing iron(III). The complexes are then adsorbed
on silica gel within a column system. Elution of the adsorbed chelate from the silica gel was performed with a small volume
of acetone containing 2.5% nitric acid. The iron is measured off-line by flame atomic absorption spectrometry. The method
can be applied to the preconcentration, separation and speciation of iron. The effects of parameters such as pH, sample flow
rate, eluent flow rate, foreign ions and ligand concentration have been investigated. The effect of humic acid that can produce
complexes with metal ions in natural systems has also been investigated. The results obtained indicate that the method is
not affected by the presence of up to 10 ppm humic acid, which would be a very high concentration to be present in natural
systems. The solid phase extraction method developed has been applied to the determination of iron in both natural water samples
and sediment samples. The LOD was found to be 0.17 mg L−1 when no preconcentration was used, although preconcentration factors of 100 could be achieved. The recovery values for spiked
samples were between 100 and 104%. The results were compared statistically with those from the standard 1,10 phenanthroline
method used for iron speciation in water systems. A Student’s t-test indicated no significant difference between the two methods. In addition, this method was applied to the analysis of
a certified sediment sample, LGC 6156. Generally, a 10-fold preconcentration factor was required for the analysis of natural
water samples. 相似文献
2.
Stéphane Laval Wissam Dayoub Leyla Pehlivan Estelle Métay Dominique Delbrayelle Gérard Mignani Marc Lemaire 《Tetrahedron letters》2014
A simple and convenient method for the chemoselective reduction of nitriles into aldehydes using a 1,1,3,3-tetramethyldisiloxane (TMDS)/triisopropoxyvanadium(V) oxide reducing system is described. Aromatic as well as aliphatic nitriles are reduced into the corresponding aldehydes in moderate to good yields. 相似文献
3.
Nonlinear Dynamics - Substitution Box (S-Box) is one of the most significant structures used to create an encryption which is strong and resistant against attacks in block encryption algorithms.... 相似文献
4.
Leyla Pehlivan Stéphane Laval Patrice Demonchaux Marc Lemaire 《Tetrahedron letters》2010,51(15):1939-10974
An efficient reduction of the nitro group with a catalytic amount of Fe(acac)3 and TMDS in THF at 60 °C affording the corresponding amine is described. 相似文献
5.
We evaluate the probabilities of various events under the uniform distribution on the set of 312‐avoiding permutations of . We derive exact formulas for the probability that the ith element of a random permutation is a specific value less than i, and for joint probabilities of two such events. In addition, we obtain asymptotic approximations to these probabilities for large N when the elements are not close to the boundaries or to each other. We also evaluate the probability that the graph of a random 312‐avoiding permutation has k specified decreasing points, and we show that for large N the points below the diagonal look like trajectories of a random walk. © 2015 Wiley Periodicals, Inc. Random Struct. Alg., 49, 599–631, 2016 相似文献
6.
In the present paper we introduce the concepts of strongly ideal convergent sequence and strong ideal Cauchy sequence in a
probabilistic metric (PM) space endowed with the strong topology, and establish some basic facts. Next, we define the strong
ideal limit points and the strong ideal cluster points of a sequence in this space and investigate some properties of these
concepts. 相似文献
7.
This research paper introduces a novel three-dimensional autonomous system, whose dynamics support periodic and chaotic butterfly attractors as certain parameters vary. A special case of this system, exhibiting reflectional symmetry, is amenable to analytical and numerical analysis. Qualitative properties of the new chaotic system are discussed in detail. Adaptive control laws are derived to achieve global chaotic synchronization of the new chaotic system with unknown parameters. Furthermore, a novel electronic circuit realization of the new chaotic system is presented, examined and realized using Orcad-PSpice program and physical components. The proposed novel butterfly chaotic attractor is very useful for the deliberate generation of chaos in applications. 相似文献
8.
This study applies fuzzy sets to integrate the supply chain network of an edible vegetable oils manufacturer. The proposed fuzzy multi-objective linear programming model attempts to simultaneously minimize the total transportation costs. The first part of the total transportation costs is between suppliers and silos; and rest one is between manufacturer and warehouses. The approach incorporates all operating realities and actual flow patterns at production/distribution network with reference to demands of warehouses, capacities of tin and pet packaging lines. The model has been formulated as a multi objective linear programming model where data are modeled by triangular fuzzy numbers. Finally, the developed fuzzy model is applied for the case study, compiled the results and discussed. 相似文献
9.
Niftaliyeva Aysel Karaduman Ali Kalwar Nazar Hussain Avci Ahmet Pehlivan Erol 《Research on Chemical Intermediates》2022,48(1):145-165
Research on Chemical Intermediates - Synthesis of Ag, Ni, Cu metallic and Ag/Ni, Ag/Cu bimetallic nanoparticles (NPs) was carried out by using metal nitrate salts as precursors via an easy and... 相似文献
10.
In this study, we investigate the statistical continuity in a probabilistic normed space. In this context, the statistical continuity properties of the probabilistic norm, the vector addition and the scalar multiplication are examined. 相似文献