Features of transition metal complexation with hydrogels

The sorption of cobalt(II), copper(II), nickel(II), iron(III), chromium(VI), and manganese(II) by polymeric strongly swelled hydrogels separately and in combination was studied by ESR and inductively coupled plasma atomic emission spectrometry (ICP-AES). The use of such hydrogels as sorbents is the novel area of their application. The features of metal ion complexation and preconcentration depending on sorption conditions are noted.     

Differentiation of neurons from neural precursors generated in floating spheres from embryonic stem cells

Background  

Neural differentiation of embryonic stem (ES) cells is usually achieved by induction of ectoderm in embryoid bodies followed by the enrichment of neuronal progenitors using a variety of factors. Obtaining reproducible percentages of neural cells is difficult and the methods are time consuming.     

Arsenazo III and its analogues-IV The electronic structure of arsenzo III in media of different acidity

By means of a single method, MOLCAO, the states of arsenazo III in strongly acidic, neutral and alkaline media has been studied. In the range from 1N sulphuric acid to pH 8, when the conjugated groups are not ionized the reagent is found in the azo form. Single stage ionization of the acidic (-OH, -NH-N) or basic (-N(2)-, CO) groups leads to a disruption of the symmetry of the system and to the appearance of the quinone-hydrazone form together with the azoide. The azoide and quinone hydrazone tautomers occur in the ratio 4:1 in concentrated sulphuric acid medium in and 22:3 alkaline medium.     

The mechanism of the distant substituent effect on molecule reactivity

The effect of distant polar substituents on the reaction mechanism of some chemical reactions is considered. It has been shown that the traditional approach, based on transferring the substituent action to the reaction centre along the chain of bonds connecting them and leading to a significant change in electronic density at the reaction centre, is wrong. The role of a polar substituent consists of changing, sometimes dramatically, the electrostatic potential character around the molecule, particularly in the space near the reaction centre.