Analysis is made of reported results on the kinetics and mechanism of ascorbic acid oxidation with oxygen in the presence of cupric ions. The diversities due to methodological reasons are cleared up. A kinetic study of the mechanism of Cu2+ anaerobic reaction with ascorbic acid (DH2) is carried out. The true kinetic regularities of catalytic ascorbic acid oxidation with oxygen are established at 2.7 6 pH < 4,5 X 6 [Cu2+] d 10-3M, and Wo = K~[CU~+][DH~][O~]~.~/[H+]where ~1 (25OC) = 0.13 f 0.01 M-o.5.sec-1. The activation energy for this reaction is E1 = 22 f 1 kcal/mol. It is found by means of adding Cu+ acceptors (acetonitrile and ally1 alcohol) that the catalytic process is of a chain nature. The Cu+ ion generation at the interaction of the Cu2+ ion with ascorbic acid is the initiation step. The rate of the chain initiation at where K~J (25OC) = (1.8 f 0.3)M-1-sec-1, Ei,l = 31 f 2 kcal/mol. The reaction of the Cu+ ion with 0 2 is involved in a chain propagation, so that the rate of catalytic ascorbic acid oxidation for the system Cu2+-DHz-02 is

PACS. 75.10.Jm -Quantized spin models. PACS. 75.40.Cx -Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.). PACS. 75.45.+j -Macroscopic quantum phenomena in magnetic systems.Abstract. -We study a system with spin-Peierls dimerization in next-nearest-neighbor (NNN) interaction and also the presence of nearest-neighbor (NN) interaction under a magnetic field. We predict the existence of different fractionally quantized magnetization plateaus with many interesting physical properties. The effect of the frustrating NNN interaction and the role of quantum fluctuations are also explored for different magnetization plateaus. We explain more physically the gapless state of spin spectrum for small values of the frustrating NNN interaction. The transition from commensurate gapped phase to incommensurate Luttinger liquid phase is of Mott-δ type.c EDP Sciences Article published by EDP Sciences and available at http://www.edpsciences.org/epl or http://dx.doi.org/10.1209/epl/i2005-10183-2 c with ∆. B) We present the curves for different magnetization plateaus. m = 1/2 is independent of ∆ and J 2 J 1 in contrast with m = 1/4, 0. The curves for m = 1/4, 0 plateaus are for ∆ = 0.5, 0.4, 0.3, respectively, from top to bottom.

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