An exploration of fractal-based prognostic model and comparative analysis for second wave of COVID-19 diffusion

Nonlinear Dynamics - The coronavirus disease 2019 (COVID-19) pandemic has fatalized 216 countries across the world and has claimed the lives of millions of people globally. Researches are being...     

Autocatalytic oxidation of β‐alanine by peroxomonosulfate in the presence of copper(II) ion

Kinetics and mechanism of oxidation of β‐alanine by peroxomonosulfate (PMS) in the presence of Cu(II) ion at pH 4.2 (acetic acid/sodium acetate) has been studied. Autocatalysis was observed only in the presence of copper(II) ion, and this was explained due to the formation of hydroperoxide intermediate. The rate constant for the catalyzed (k) and uncatalyzed (k) reaction has been calculated. The kinetic data obtained reveal that both the reactions are first order with respect to [PMS]. k values initially increase with the increase in [β‐alanine] and reach a limiting value, but k values decrease with the increase in [β‐alanine]. k values increase linearly with the increase in [Cu(II)], whereas k values increase with [Cu(II)]². Furthermore, k values are independent of [acetate], but k values decrease with the increase in acetate. A suitable mechanism has been proposed to explain the experimental observation. The reaction has been studied at different temperatures, and the activation parameters are calculated. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 44–49, 2008     

Cobalt(III), nickel(II) and ruthenium(II) complexes of 1,10-phenanthroline family of ligands: DNA binding and photocleavage studies

DNA binding and photocleavage characteristics of a series of mixed-ligand complexes of the type [M(phen)₂LL]ⁿ⁺ (where M = Co(III), Ni(II) or Ru(II), LL = 1,10-phenanthroline (phen), phenanthroline-dione (phen-dione) or dipyridophenazine (dppz) andn = 3 or 2) have been investigated in detail. Various physico-chemical and biochemical techniques including UV/Visible, fluorescence and viscometric titration, thermal denaturation, and differential pulse voltammetry have been employed to probe the details of DNA binding by these complexes; intrinsic binding constants (K _b) have been estimated under a similar set of experimental conditions. Analysis of the results suggests that intercalative ability of the coordinated ligands varies as dppz>phen>phen-dione in this series of complexes. While the Co(II) and Ru(II) complexes investigated in this study effect photocleavage of the supercoiled pBR 322 DNA, the corresponding Ni(II) complexes are found to be inactive under similar experimental conditions. Results of detailed investigations carried out inquiring into the mechanistic aspects of DNA photocleavage by [Co(phen)₂(dppz)]³⁺ have also been reported.     

Mechanistic Investigation of the Oxidation of Lysine by Oxone

The kinetics and mechanism of oxidation of lysine, a basic α-amino acid, by oxone in an acetic acid/sodium acetate buffered medium (pH = 3.6–5.2) at 308 K has been investigated. The rate of disappearance of oxone at constant [lysine] and pH follows the equation:

Dimerization of phenols and naphthols using an aqueous sodium hypochlorite

The observation of an unusual dimerization of phenols and naphthols using a sodium hypochlorite (NaOCl) in an aqueous solution is reported. NaOCl is an environmentally friendly and less expensive reagent than previously used reagents for dimerization. The yield of the dimer is moderate to high at ambient temperature.     

E(2)-Elimination in the Decomposition of N-Bromoamino Acid Anions

The kinetics of oxidation of eight structurally different amino acids by hypobromite ion (BrO(-)) in the presence of hydroxide ion has been studied. The reactions proceed through the rapid formation of N-bromoamino acid anion which then decomposes in the rate-limiting step. The decomposition of N-bromoamino acid anions is found to proceed through an unimolecular and a base-catalyzed reaction. The large negative values of DeltaS() and the products formed suggest that the hydroxide ion-catalyzed reactions proceed through an E(2) mechanism. N-Bromoamino acid anion gives an absorption spectrum with lambda(max) at approximately 290 nm.