Synthesis,crystal structure,and antimicrobial studies of <Emphasis Type="Italic">trans</Emphasis>-[Pd(PPh<Subscript>3</Subscript>)<Subscript>2</Subscript>(imidazolidine-2-thione)<Subscript>2</Subscript>]Cl<Subscript>2</Subscript> · 3.5H<Subscript>2</Subscript>O

The palladium(II) complex, [Pd(PPh₃)₂(Imt)₂]Cl₂ · 3.5H₂O (I) (Imt = imidazolidine-2-thione), has been synthesized and characterized by IR, NMR, and X-ray crystallography. An upfield shift in the >C=S resonance of Imt in the ¹³C NMR spectrum and a downfield shift in the N-H resonance in ¹H NMR are consistent with the sulfur coordination of Imt to palladium(II). In the crystal structure of I, the central palladium atom is coordinated to two thione sulfur atoms of Imt and to two phosphorus atoms possessing a square-planar environment with the average cis and trans bond angles of 89.60° and 167.31°, respectively. The title complex was screened for antimicrobial effects, and the results showed that it exhibits moderate activities against gram-negative bacteria (E. coli, P. aeruginosa). The complexes also exhibited significant activities against yeast (C. albicans, S. serevisaiae).     

Adsorption of acid yellow dye on flakes of chitosan prepared from fishery wastes

Chitosan flakes, extracted from prawns and labeo rohita scales, with high adsorption capacity were prepared after chemical treatment and were used to remove acid yellow dye from water. The results showed that adsorption capacity is dependent on pH, initial concentration of dye, BET, Langmuir surface area and pore volume of the adsorbent. In acidic conditions, the polymer amino groups were protonated (positively charged polymer chain), which showed attraction with negative ions of anionic dye. Chitosan from prawns scales showed higher dye adsorption under the same experimental conditions. Adsorption isotherms were developed and equilibrium data fitted well to Langmuir and Freundlich isotherm models.     

Dendritic growth with interfacial energy anisotropy

A theory for dendritic growth of needle shaped crystals growing in supercooled pure melts and dilute alloys is proposed. This theory predicts the growth velocity and tip radii as functions of supercooling and alloy concentrations without introduction of additional conditions such as marginal stability. A key ingredient of the theory is introducing the effect of the interfacial energy anisotropy. Deviation of the shape of the dendrite from a paraboloid of revolution is permitted, consistent with a small interfacial energy anisotropy. The radius of curvature and the growth rate as functions of melt supercooling and alloy concentrations are determined in terms of the anisotropy, and are compared with experimental results. The predictions are in agreement with the experimental results, especially at large supercoolings. The deviation at lower supercoolings can be attributed to the neglect of natural convection in the present theory.     

A fourth-order accurate method for fourth-order two-point nonlinear boundary value problems

A fourth-order accurate finite difference method is developed for a class of fourth order nonlinear two-point boundary value problems. The method leads to a pentadiagonal scheme in the linear cases, which often arise in the beam deflection theory. The convergence of the method is tested numerically on examples from the literature.     

Synthesis,characterization and antibacterial activity of palladium(II) bromide complexes of thioamides; X-ray structure of [Pd(tetramethylthiourea)<Subscript>4</Subscript>]Br<Subscript>2</Subscript>

Palladium(II) bromide complexes of thioamides having the general formulae [PdL₂Br₂] and [PdL₄]Br₂ where L = Thiourea (Tu), Methylthiourea (Metu), Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), Imidazolidine-2-thione (Imt), Mercaptopyridine (Mpy), Mercaptopyrimidine (Mpm) and Thionicotinamide (Tna) were prepared by reacting K₂[PdCl₄] with KBr and the corresponding thioamides. The complexes were characterized by elemental analysis, IR and NMR spectroscopy, and one of them, [Pd(Tmtu)₄]Br₂ (1) by X-ray crystallography. The crystal structure of 1 shows a square-planar coordination environment around the Pd(II) atoms with the average cis and trans S–Pd–S bond angles of 90.0° and 180.0°, respectively. The synthesized complexes were screened for antibacterial effects, and the results showed that the complexes exhibit significant activities against both gram positive and gram negative bacteria.     

Numerical techniques for a class of unilateral problems

In this paper, we use the variational inequality theory coupled with Pade approximants to obtain an approximate solution for a class of unilateral problems in elasticity. The results obtained are more efficient than the previously known methods of the same order. The variational inequality formulation is used to discuss the problem of uniqueness and existence of the solution of these unilateral problems.     

Synthesis of New Naphthyl Aceto Hydrazone-Based Metal Complexes: Micellar Interactions,DNA Binding,Antimicrobial, and Cancer Inhibition Studies

In the present study, naphthyl acetohydrazide (HL) ligand was prepared and used for the synthesis of new six amorphous transition metal (Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II)) complexes. All the compounds were characterized by elemental analysis, UV-vis, FT-IR, ¹H- and ¹³C-NMR, and Matrix-Assisted Laser Desorption Ionization (MALDI). The solubilization study was carried out by estimating the interaction between the metal complexes with surfactants viz. sodium stearate (SS) and Cetyltrimethylammonium bromide (CTAB). UV-Visible spectroscopy was employed to determine partitioning and binding parameters, whereas electrical conductivity measurements were employed to estimate critical micellar concentration (CMC), the extent of dissociation, and free energy of micellization. The CT-DNA interaction of synthesized compounds with DNA represents the major groove binding. The synthesized ligand and metal complexes were also tested against bacterial and fungal strains and it has been observed that Cu(II) complex is active against all the strains except Candida albicans, while Cd(II) complex is active against all bacterial and fungal strains except Pseudomonas. Among all compounds, only the Pd(II) complex shows reasonable activity against cervical cancer HeLa cell lines, representing 97% inhibition.     

Selective Complexation of Hydrazone Based Ketimine with 3d, 4d,and 5d Metals: Synthesis,Characterization, and Biological Activity

Russian Journal of General Chemistry - The hydrazone derived ketimine of dehydroacetic acid and its metal {Cu(II), Ni(II), Zn(II), Fe(III), Cd(II), Pd(II), La(III), Nd(III), Ce(III)} complexes are...     

Meshless method of lines for the numerical solution of generalized Kuramoto-Sivashinsky equation

In this paper, the numerical solution of the generalized Kuramoto-Sivashinsky equation is presented by meshless method of lines (MOL). In this method the spatial derivatives are approximated by radial basis functions (RBFs) giving an edge over finite difference method (FDM) and finite element method (FEM) because no mesh is required for discretization of the problem domain. Only a set of scattered nodes is required to approximate the solution. The numerical results in comparison with exact solution using different radial basis functions (RBFs) prove the efficiency and accuracy of the method.