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141.
B Abramovitz M Berezina A Berman 《International Journal of Mathematical Education in Science & Technology》2013,44(3):465-475
This note is a possible contribution to the teaching of mathematics. We present a variety of examples of wrong proofs, misinterpreted definitions and the mistaken use of theory. The examples are based on our experience of teaching mathematics to engineering students. They include elementary examples and more advanced ones, and are taken from different subjects. In analysing the mistakes, we try to use them to improve the students' understanding. 相似文献
142.
Buma Abramovitz Miryam Berezina Abraham Berman 《International Journal of Mathematical Education in Science & Technology》2013,44(8):1233-1248
In this paper we describe a method for teaching students to prove some mathematical statements independently, by using specially designed auxiliary assignments. The assignments are designed as homework problems and can be adapted for online learning. We illustrate our method using examples from calculus and differential equations. 相似文献
143.
G. R. Berezina T. A. Rumyantseva V. P. Kulinich G. P. Shaposhnikov 《Russian Journal of Coordination Chemistry》2011,37(10):796-799
An analysis of the electronic optical properties and solubility in chloroform and DMF of the erbium and ytterbium complexes
with porphyrazine and its octaphenyl- and octa(p-alkylsulfamoylphenyl)-substituted derivatives and tetrapyrazinoporphyrazine and its octaethyl-, tetra(tert-butyl)-, and octaphenyl-substituted derivatives is presented. The dependence of the electronic optical properties and solubility
on the composition of the macrocycle of the studied complexes, namely, on the nature of the extraligand and peripheral environment
of the porphyrazine macrocycle, is shown. 相似文献
144.
145.
Falina Irina V. Berezina Ninel P. Sytcheva Anna A.-R. Pisarenko Ekaterina V. 《Journal of Solid State Electrochemistry》2012,16(5):1983-1991
Changes in the conducting and hydrophilic properties of composites MF-4SC/polyaniline (PAni) under conditions of prolonged
synthesis have been studied. A maximum of PAni content of about 0.20 by weight, which can be incorporated into the matrix
of MF-4SC under these conditions of synthesis, is determined. Percolation behavior of electrical conductivity of the composites
after drying was observed. The conductivity of PAni salt inside MF-4SC was estimated within the frames of the percolation
model. Using the fibrous cluster model of the membrane and the conductivity data on individual PAni, theoretical assessment
of the electrical conductivity of nanocomposite MF-4SC/PAni has been performed. Reasons for a significant reduction in the
conductivity of PAni during its integration into the structure of the initial matrix were discussed. A scale of membrane conductivity,
reflecting changes in the electrical conductivity of composites at various stages of synthesis, was drawn. 相似文献
146.
N. A. Kononenko S. V. Dolgopolov N. P. Berezina N. V. Loza S. G. Lakeev 《Russian Journal of Electrochemistry》2012,48(8):857-861
The effect of asymmetry of the voltammetric characteristics is studied on anisotropic composites obtained using the technique of polyaniline matrix synthesis in the surface layer of the MF-4SK membrane. On the basis of studies of the ohmic voltammetric curve section in a series of isomolar HCl-NaCl solutions, independence of the membrane conductivity on the fraction of protons in the solution is established in the case when the modified membrane side is turned towards the counterion flow. In the case of the reverse orientation, the membrane conductivity is changed symbatically at an increase in the proton content in the mixed solution. An explanation of this effect is suggested with account for the regularities of the concentration profile formed in the bilayer membrane under polarization, water decomposition on the inner bipolar boundary, and also a change in the energy state of water in the composite membrane. 相似文献
147.
N. P. Berezina N. P. Gnusin O. A. Demina L. A. Annikova 《Russian Journal of Electrochemistry》2009,45(11):1226-1233
Concentration dependences of the specific electrical conductivity of ion-exchange resin KU-2 and ion-exchange heterogeneous
membrane MK-40 made thereof are obtained and compared prior to and after the membrane modification with polyaniline. It is
shown that the introducing of the polyaniline to polymer matrices of ionites results in the change of the specific electrical
conductivity of both the resin KU-2 and the membrane MK-40, which correlates with the earlier data obtained for the MF-4SK/polyaniline
composites. The quantitative evaluation of the polyaniline effect on the mechanism of current passing through structural fragments
of initial and modified ionites is carried out. To this purpose, model parameters were used, which reflect the current paths
and the conducting phases’ volume fractions and spatial orientation. 相似文献
148.
N. M. Berezina M. I. Bazanov A. A. Maksimova A. S. Semeikin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(12):2377-2382
The effect meso-substitution in iron porphyrin complexes has on their redox behavior in alkaline aqueous solutions is studied via cyclic voltammetry. The voltammetric features of the reduction of iron pyridylporphyrins suggest that the sites of electron transfer lie at the ligand, the metal ion, and the pyridyl moieties. The electron transfer reactions between the different forms of these compounds, including the oxygen reduction reaction they mediate, are outlined to show the sequence and potential ranges in which they occur in alkaline aqueous media. Under our experimental conditions, the iron porphyrins exist as μ-oxo dimmers whose activity for the electrocatalytic reduction of oxygen displays a considerable dependence on the nature of the substitutents and nitrogen isomerization (for pyridylporphyrins) and grows in the order (Fe(ms-Ph)4P)2О, (Fe[ms-(Py-3)Ph3]P)2O, (Fe[ms-(Py-4)4]P)2O, and (Fe[ms-(Py-3)4]P)2O. 相似文献
149.
N. P. Berezina N. A. Kononenko N. V. Loza A. A. -R. Sycheva 《Russian Journal of Electrochemistry》2007,43(12):1340-1349
Membrane voltammetry was used to investigate composites consisting of perfluorinated MF-4SK membranes and polyaniline (PANI) and synthesized under various conditions. A theoretical analysis of the influence of transport-structure parameters of the ion-exchange membranes on their selectivity and limiting-current value is carried out. For MF-4SK/PANI composites, the increase in the exchange potential at the overlimiting state is found to be more than 2V compared to the original membrane. An analysis of how various factors influence the parameters of a current-voltage curve shows that the presence of anilinium and Fe3+ ions in the electromembrane system has no effect on the value of the potential at the onset of the overlimiting state. A phenomenological model is proposed to account for the increased plateau length at the limiting current through a change in the energetic state of water in the perfluorinated-membrane matrix resulting from the template synthesis of polyaniline. 相似文献
150.
G. R. Berezina Yu. G. Vorob’ev S. M. Vorob’eva I. A. Andreikina 《Russian Journal of General Chemistry》2004,74(8):1254-1258
Symmetrical macroheterocyclic compounds are synthesized by the reaction of 1H-phenalene-1,3(2H)-diimine with m-phenylenediamine, 2,6-diaminopyridine, and 2,5-diamino-1,3,4-thiadiazole. IR and UV spectral data are given.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1355–1359.Original Russian Text Copyright © 2004 by Berezina, Vorobev, Vorobeva, Andreikina.This revised version was published online in April 2005 with a corrected cover date. 相似文献