Effect of herd shape in a diffusive predator-prey model with time delay

In this paper, we deal with the effect of the shape of herd behavior on the interaction between predator and prey. The model analysis was studied in three parts. The first, The analysis of the system in the absence of spatial diffusion and the time delay, where the local stability of the equilibrium states, the existence of Hopf bifurcation have been investigated. For the second part, the spatiotemporal dynamics introduce by self diffusion was determined, where the existence of Hopf bifurcation, Turing driven instability, Turing-Hopf bifurcation point have been proved. Further, the order of Hopf bifurcation points and regions of the stability of the non trivial equilibrium state was given. In the last part of the paper, we studied the delay effect on the stability of the non trivial equilibrium, where we proved that the delay can lead to the instability of interior equilibrium state, and also the existence of Hopf bifurcation. A numerical simulation was carried out to insure the theoretical results.     

Synthesis and pharmacological evaluation of 9(10H)-acridone bearing 1,3,4-oxadiazole derivatives as antimicrobial agents

In the present study a new acridone derivatives were synthesized. The newly synthesized compounds were characterized by IR, NMR and C, H, N, S analyses. All newly synthesized compounds were screened for their antibacterial (Staphylococcus aureus, Streptococcus viridans and Escherichia coil) and antifungal (Gibberela, Cercospora arachidicola, Physolospora piricola and Fusarium oxysporum) studies. The results revealed that all synthesized compounds have a significant biological activity against the tested microorganisms.     

Preparation, spectroscopic properties and thermal stabilities of organomercury compounds containing the bulky ligand (Me3Si)3C or (PhMe2Si)3C

Mercury compounds of the types HgR¹R (R¹ = C(SiMe₃)₃; R = Me, ⁱPr, Bu, ^tBu or Ph) and HgR²R(R² = C(SiMe₂Ph)₃; R = Me, Bu, CH₂Ph or Ph) have been prepared. Those containing R¹ were made by reactions of the bromides HgR¹Br with the Grignard reagents MgRX, and those containing R² by reaction of HgR²Cl with LiR or, for R = CH₂Ph, with Mg(CH₂Ph)Cl. Replacement of one R group in HgR₂ by the bulky R¹ or R² group leads to a large increase in thermal stability, a marked shift in the ¹⁹⁹Hg resonance to lower frequency and an increase in the coupling constant ¹J(¹³C---¹⁹⁹Hg) for the Hg---R bond. The compound HgR²Cl does not react further with LiR² in tetrahydrofuran, but with LiR¹ gives HgR¹R²; the arrangement of the SiMe₂Ph groups in the latter in solution in CH₂C12 at low temperature appears to be different from that in the solid.     

Upon the hydrogen-bonding ability of the H4 and H5 protons of the imidazolium cation

The crystal and molecular structures of [Me₂Etim]Cl, [Me₂Etim]₂[CoCl₄], and [Me₂Etim]₂[NiCl₄] ([Me₂Etim]⁺ = 1,2-dimethyl-3-ethylimidazolium cation) all contain evidence that the H4 and H5 protons of the imidazolium cation enter into hydrogen bonds; the implications of this observation for the interactions in room-temperature chloroaluminate(III) ionic liquids are considered.     

Some observations on an indirect atomic absorption spectrophotometric method for the microdetermination of chlorine or bromine in organic compounds

An atomic absorption spectrophotometric method for the microdetermination of chlorine or bromine in organic compounds is described; it is based on oxygen flask combustion to yield chloride or bromide, which is then reacted with an excess of solid silver chromate, followed by collection of the combined unreacted silver chromate and chloride or bromide preipitate and AAS determination of the free chromate (equivalent of the chloride or bromide originally present) at 358.2 nm. The method was applied satisfactorily to a wide range of chlorine or bromine containing organic compounds with an average absolute error of ± 0.23 and a coefficient of variation (seven determinations) of better than 2%.     

Synthesis and spectral characterization of macrocyclic Schiff base by reaction of 2,6-diaminopyridine and 1,4- bis (2-carboxyaldehydephenoxy)butane and its CuII, NiII, PbII, CoIII and LaIII complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:15,16-tribenzo-9,15-dioxacycloheptadeca-1,5-diene (L) was synthesized by reaction of 2,6-diaminopyridine with 1,4-bis(2-carboxyaldehydephenoxy)butane. Then, its Cu^II, Ni^II, Pb^II, Co^III and La^III complexes were synthesized by the template effect by reaction of 2,6-diaminopyridine and 1,4-bis (2-carboxyaldehydephenoxy)butane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La (NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes were characterized by elemental analysis, IR, ¹H- and ¹³C-n.m.r., UV-vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements and mass spectra. All complexes are diamagnetic and the Cu^II complex is binuclear. The Co^II complex was oxidised to Co^III.     

Evaluation of two-center overlap integrals using slater type orbitals in terms of bessel type orbitals

Using the definition of STOs in terms of BTOs, we have presented analytical formula for two-center overlap integrals. The obtained formula contains generalized binomial coefficients and Mulliken integrals A_k and B_k. Taking into account the recent advances on the efficient calculation of Mulliken integrals (Harris, Int. J. Quantum Chem., 100 (2004) 142), we have obtained many more satisfactory results for two-center overlap integrals, for arbitrary quantum numbers, scaling parameters, and location of atomic orbitals.PACS No: 31.15.+qAMS Subject Classification: 81V55, 81–08     

Spectroscopic and Electrochemical Studies of Transition Metal Complexes with N,N′-Bis(2-aminothiophenol)-1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and Structure Effects on Extractability of Ligand towards some Divalent Cations

Summary. La(III), Cu(II), Ni(II), and Zn(II) metal complexes with a novel quadridentate Schiff base derived from 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and 2-aminothiophenol were synthesized and characterized by microanalytical data, elemental analysis, magnetic measurements, ¹H NMR, ¹³C NMR, UV-Vis, IR, mass spectra, cyclic voltammetric and conductance measurements. The extractability of divalent cations was evaluated as a function of relationship between distribution ratio of the metal and pH or ligand concentration. The highest extraction percentage of Cu²⁺ and Ni²⁺ showed pH 7.0 and 6.4. It was concluded that the ligand can effectively be used in solvent extraction of copper(II) and nickel(II) from the aqueous phase to the organic phase.     

Synthesis and Characterization of New Macrocyclic Cu（Ⅱ） Complexes from Various Diamines, Copper（Ⅱ） Nitrate and 1,4-Bis（2-formylphenoxy）butane

Six new macrocyclic complexes were synthesized by a template reaction of 1,4-bis（2-formylphenoxy）butane with diamines and Cu（NO3）2·3H2O and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The metal to ligand molar ratios of the Cu（Ⅱ） complexes were found to be 1 ： 1. The Cu（Ⅱ） complexes are 1 ： 2 electrolytes as shown by their molar conductivities （∧m） in DMF at 10^-3 mol·L^-1. Due to the existence of free ions the Cu（Ⅱ） complexes are electrically conductive. Their configurations were proposed to be probably distorted octahedral.