Generation of potential energy curves for the X1Sigma(+)g, B1Delta(+)g, and B'1Sigma(+)g states of C2 using the effective valence shell Hamiltonian method

Calculations of the ground and excited state potential energy curves of C2 using the third-order effective valence Hamiltonian (Hv3rd) method are benchmarked against full configuration interaction and other correlated single-reference perturbative and nonperturbative theories. The large nonparallelity errors (NPEs) exhibited even by state-of-art coupled cluster calculations through perturbative triples indicate a serious deficiency of these single-reference theories. The Hv method, on the other hand, produces a much reduced NPE, rendering it a viable approximate many-body method for accurately determining global ground and excited state potential energy curvessurfaces.     

Thermally induced isomeric transformations ofbis-(diamine) complexes of nickel(II) nitrate in the solid phase

Summary Thermal reactions of [Ni(diamine)₂(H₂O)₂](NO₃)₂ and [Ni(diamine)₂(NO₃)₂] (where diamine=1,2-ethanediamine,N-methyl-1,2-ethanediamine,N-ethyl-1,2-ethanediamine, 1,3-propanediamine andN-methyl-1,3-propanediamine) have been investigated in the solid phase. The 1,2-ethanediamine andN-methyl-1,2-ethanediamine complexes undergo thermally induced endothermic irreversible isomeric transformations. In the 1,2-ethanediamine complex the transformation is thermochromic, whereas it is not for theN-methyl-1,2-ethanediamine complex. The transformations are explained in terms of the axial interaction of NO₃ ions with nickel as well as to ligand field weakening resulting from conformational changes of the individual diamine chelate rings.Supplememtary data available: X-ray powder diffraction data (Table3).     

Massenspektrometrische-, dta- und tg-untersuchungen an eisencarbonylchalkogeniden Fe2(CO)6X2 (X  S,Se) und Fe3(CO)9X′2 (X′  S,Se, Te)

Mass spectra of Fe₃(CO)₉X₂ (X  S, Se, Te) and Fe₂(CO)₆X′₂ (X′  S, Se) are recorded and their fragmentation pattern given. The thermal decarbonylation has been studied using DTA/TG methods in the temperature range 25–600°C. The results are compared with those obtained from mass-spectroscopic studies. X-ray and magnetic measurements have been carried out on the residues obtained in the decarbonylation process.     

Effect of amines on the ceric ion-initiated polymerization of vinyl monomers. II. Polymerization of acrylonitrile by ceric ion in presence of various substituted amines

The effect of various substituted amines on the polymerization of acrylonitrile initiated by ceric ammonium sulfate has been studied in aqueous solution at 30°C. It was found that the secondary and tertiary amines considerably increased the rate of polymerization, whereas the primary amines seemed to have no effect at all. From the kinetic studies it was found that the overall polymerization rate R_p is independent of ceric ion concentration and can be expressed by the equation: R_p = k₁ [amine] [monomer] + k₂[monomer]², where k₁ and k₂ are constants (involving different rate constants). The accelerating effect of the amines was attributed to a redox reaction between the ceric ion and the amine involving a single electron transfer, the relative activity of the different amines being thus dependent on the relative electron-donating tendency of the substituents present in the amine. The mechanism of the polymerization is discussed on the basis of these results, and various kinetic constants are evaluated.     

Supply-chain coordination model with insufficient production capacity and option for outsourcing

In this paper, a mathematical model is developed to analyze the situation of lost sales from the supply-chain coordination perspective. In a two-stage supply chain, the supplier’s production capacity is less than the annual demand of the retailer. The supplier may recover the deficit by procuring the same from an external source at a certain price and then supplying it back to the retailer. Here, the conditions have been derived when the practice of external procurement may be a viable solution to enhance the profits of both the supplier and retailer in a coordinated approach. A numerical example is carried out to illustrate the efficacy of the developed model and the procedure developed for solving the problem.     

Bioeconomic harvesting of a schooling fish species: A dynamic reaction model

This paper develops a mathematical model for growth and exploitation of a schooling fish species, using a realistic catchrate function and imposing a tax on the catch to control harvesting. Fishing effort is assumed to depend on the net revenue. The steady states of the system are determined and their local and global stability are discussed. Taking the tax as a control variable; the optimal harvest policy is formulated and solved as a control problem. The results are illustrated with the help of a numerical example.