Evaluation of dipolar shifts and paramagnetic anisotropy in penta coordinated cobalt(II) complexes

The isotropic proton shifts for the pyridine N-oxide and γ-picoline N-oxide protons have been observed in the penta coordinated adducts of these bases with bis[di(p-tolyl)dithiophosphinato] cobalt(II). The contribution to the observed shifts due to dipolar interaction has been calculated. From the dipolar shifts, it was ascertained that the pyridine N-oxide complexes have a bent structure in solution with a Co-O-N angle of 125°. An estimate of the paramagnetic anisotropy of the cobalt complex yields K_?-K_⊥ = 4244 × 10^?6 cm³/mole.     

Enhanced podophyllotoxin production from Agrobacterium rhizogenes transformed cultures of Podophyllum hexandrum

Podophyllotoxin, a potent chemotherapeutic agent is obtained from Podophyllum hexandrum Royle. Embryos of P. hexandrum were transformed using different strains of Agrobacterium rhizogenes viz. A4, 15834, K599. Transformed nature of the calli was ascertained and the cultures were further maintained as individual clones. HPLG analysis of transformed cultures depicted a three-fold increase in podophyllotoxin content in comparison to controls.     

Approximate solutions and scalarization in set-valued optimization

Abstract

Certain notions of approximate weak efficient solutions are considered for a set-valued optimization problem based on vector and set criteria approaches. For approximate solutions based on the vector approach, a characterization is provided in terms of an extended Gerstewitz’s function. For the set approach case, two notions of approximate weak efficient solutions are introduced using a lower and an upper quasi order relations for sets and further compactness and stability aspects are discussed for these approximate solutions. Existence and scalarization using a generalized Gerstewitz’s function are also established for approximate solutions, based on the lower set order relation.     

Well-setness and scalarization in set optimization

In this paper, we consider a notion of global well-setness for a set optimization problem using the excess function. We give sufficient conditions for well-setness and establish Dontchev–Zolezzi type measure for well-setness. Moreover, we relate this notion with well-setness notion for a scalar problem obtained by using generalized Gerstewitz’s function.     

Optimization reformulations of the generalized Nash equilibrium problem using regularized indicator Nikaidô–Isoda function

In this paper, we extend the literature by adapting the Nikaidô–Isoda function as an indicator function termed as regularized indicator Nikaidô–Isoda function, and this is demonstrated to guarantee existence of a solution. Using this function, we present two constrained optimization reformulations of the generalized Nash equilibrium problem (GNEP for short). The first reformulation characterizes all the solutions of GNEP as global minima of the optimization problem. Later this approach is modified to obtain the second optimization reformulation whose global minima characterize the normalized Nash equilibria. Some numerical results are also included to illustrate the behaviour of the optimization reformulations.     

Proton magnetic resonance studies of the association of amino methyl pyridines

Proton magnetic resonance studies of the solutions of (a) 2-amino, 3-methyl pyridine and (b) 2-amino, 6-methyl pyridine in carbontetrachloride show that in these molecules there is an equilibrium between monomers and hydrogen-bonded dimers. The equilibrium constants for the two cases have been obtained. Evidence has also been obtained to show that chloroform forms hydrogen bond with the ring nitrogen of these compounds. These NMR results have been compared with those obtained earlier from infra-red studies.     

Crystal structure of zeolite MCM-68: a new three-dimensional framework with large pores

The crystal structure of the aluminosilicate MCM-68 was solved from synchrotron powder diffraction data by the program FOCUS. The unit cell framework contains Si100.6Al11.4O224. This material crystallizes in space group P42/mnm, where, after Rietveld refinement, a=18.286(1) A and c=20.208(2) A. A three-dimensional framework is found that contains continuous 12-ring channels and two orthogonal, intersecting, undulating 10-ring channels. Rietveld refinement of the model coordinates optimizes the framework geometry, to match the observed intensity profile by Rwp=0.1371, R(F2)=0.1411. It is not possible to determine the location of approximately 0.84 K+ cations remaining in the unit cell after the material is steamed and then dehydrated. The framework model also successfully predicts observed electron diffraction data in two projections, and the tetragonal projection can be determined independently from these data by direct methods. The calculated density of the framework structure is 1.66 g/cm3, and the T-site framework density is 16.6 T/1000 A3.     

A higher-order hybrid spline difference method on adaptive mesh for solving singularly perturbed parabolic reaction–diffusion problems with robin-boundary conditions

We propose a hybrid numerical scheme to discretize a class of singularly perturbed parabolic reaction–diffusion problems with robin-boundary conditions on an equidistributed grid. The hybrid difference scheme is developed by using a modified backward difference scheme in time, a combination of the cubic spline and exponential spline difference scheme in space. The proposed scheme uses a cubic spline difference scheme for the discretization of robin-boundary conditions. For the time discretization of the problem, we use the standard uniform mesh while a layer adapted equidistributed grid is generated for the spatial discretization. By equidistributing a curvature-based monitor function, the spatial adaptive grid is able to capture the presence of parabolic boundary layers without using any prior information about the solution. Parameter uniform error estimates are derived to illustrate an optimal convergence of first-order in time and second-order in space for the proposed discretization. The accuracy of the proposed scheme is confirmed by the numerical experiments that underpin the theoretical analysis.     

NMR and IR studies of the interactions of compounds containing OH group with some ethylenes

Interactions of compounds containing OH group with acrylonitrile, 2 : 3 dichloropropene, allyl cyanide and allyl halides have been studied using NMR and IR techniques. Hydrogen bonds of the type O-H ··· N have been detected. With allyl halides bonds of the type O-H ··· Cl have been detected for allyl chloride only. The value of the equilibrium constant has been calculated for O-H ··· N bonds using IR studies.