Modeling the effect of mutual interference in a delay-induced predator-prey system

In this paper, we investigate the effect of mutual interference on the dynamics of a predator-prey system with gestation delay. It has been observed that there is stability switches and system becomes unstable due to the combine effect of mutual interference and time delay. We determine the conditions under which the model system becomes globally asymptotically stable around the non-zero equilibria. By applying the normal form theory and the center manifold theorem, the explicit formulae which determine the stability and direction of the bifurcating periodic solutions are determined. Computer simulations have been carried out to illustrate different analytical findings.     

Untersuchungen über die Chelate einiger seltenerer Übergangsmetalle,I. Mitt: Ir(III), Pt(IV) und Au(III)

Chelates of bidentate ligands, p-dimethylamino and p-diethylaminoanils of 3-benzoylmethylglyoxal with Ir(III), Pt(IV) and Au(III) ions have been studied for their stoichiometry, electrolytic nature, infrared, magnetic, and electronic spectra. In addition to the elucidation of stereochemistry and structures various ligand field parameters have been calculated and unusual paramagnetic behaviour has been accounted for.     

Improved and rapid synthesis of new coumarinyl chalcone derivatives and their antiviral activity

Two closely structurally related coumarins, 4-hydroxy-8-isopropyl-5-methylcoumarin and 4-hydroxy-6-chloro-7-methylcoumarin were acylated at C-3 and further converted to the respective chalcones and two series of eighteen new compounds, which were evaluated for possible antiviral activity.     

Insertion of a small peptide of six amino acids into the β7–β8 loop of the p51 subunit of HIV-1 reverse transcriptase perturbs the heterodimer and affects its activities

Background  

HIV-1 RT is a heterodimeric enzyme, comprising of the p66 and p51 subunits. Earlier, we have shown that the β7-β8 loop of p51 is a key structural element for RT dimerization (Pandey et al., Biochemistry 40: 9505, 2001). Deletion or alanine substitution of four amino acid residues of this loop in the p51 subunit severely impaired DNA binding and catalytic activities of the enzyme. To further examine the role of this loop in HIV-1 RT, we have increased its size such that the six amino acids loop sequences are repeated in tandem and examined its impact on the dimerization process and catalytic function of the enzyme.     

Platinum(IV) complexes of reducing sugars in an alkaline medium and their resistance to reaction with N-bromosuccinimide. A kinetic study

Spectrophotometric studies support the formation of { Pt^IV–S} (where S = glucose, galactose and fructose) complexes in an alkaline medium. The resistance of these complexes to reaction with N-bromosuccinimide (NBS) has been observed. The kinetic data also support the formation of { Pt^IV –S} complexes.     

Asymmetric dihydroxylation route to (R)-isoprenaline, (R)-norfluoxetine and (R)-fluoxetine

An efficient asymmetric synthesis of enantiomerically pure (R)-isoprenaline, (R)-norfluoxetine and (R)-fluoxetine is described using Sharpless asymmetric dihydroxylation as the key step.     

Kinetics and mechanism of the ruthenium(III)-catalysed oxidation of aminoalcohols by alkaline hexacyanoferrate(III)

Summary The kinetics of the ruthenium(III)-catalysed oxidation of aminoalcoholsviz. 2-aminoethanol and 3-aminopropanol by alkaline hexacyanoferrate(III) has been studied spectrophotometrically. The reactions are rapid initially, then follow a second order rate dependence with respect to each of the catalyst and the oxidant. The second order rate dependence with respect to ruthenium(III) was observed for the first time. The order in [Aminoalcohol] and [OH^–] is unity in each case. A suitable mechanism, consistent with the observed kinetic data is postulated.     

The Benson - Symonds Invariant for Permutation Modules

In a recent paper, Dave Benson and Peter Symonds defined a new invariant γ_G(M) for a finite dimensional module M of a finite group G which attempts to quantify how close a module is to being projective. In this paper, we determine this invariant for permutation modules of the symmetric group corresponding to two-part partitions using tools from representation theory and combinatorics.

     

Age-group-targeted testing for COVID-19 as a new prevention strategy

Nonlinear Dynamics - Robust testing and tracing are key to fighting the menace of coronavirus disease 2019 (COVID-19). This outbreak has progressed with tremendous impact on human life, society and...