Kinetics and mechanism of oxidation of iodide with a (μ‐oxo)diiron(III,III) complex in weakly acidic media

The complex ion [Fe^III₂(μ‐O)(phen)₄(H₂O)₂]⁴⁺ ( 1 ) (phen = 1,10‐phenanthroline) and its hydrolytic derivatives [Fe^III₂(μ‐O)(phen)₄(H₂O)(OH)]³⁺ ( 1a ) and [Fe^III₂(μ‐O)(phen)₄‐ (OH)₂]²⁺ ( 2a ) coexist in rapid equilibria in the range pH 4.23–5.35 in the presence of excess phenanthroline (pK_a1 = 3.71±0.03, pK_a2 = 5.28± 0.07). The solution reacts quantitatively with I⁻ to produce [Fe(phen)₃]²⁺ and I₂. Only 1 but none of its hydrolytic derivatives is kinetically active. Both inner and outer sphere pathways operate. The observed rate constants show second‐order dependence on the concentration of iodide, while the dependence on [H⁺] is complex in nature. Added Cl⁻ inhibits the formation of adduct with I⁻ and thus retards the rate of inner sphere path, leading to a rate saturation at high [Cl⁻], where only the outer sphere mechanism is active. Kinetic data indicate that simultaneous presence of two I⁻ in the vicinity of diiron core is necessary for the reduction of 1 . © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 737–743, 2005     

Inverse Scattering and Soliton Solutions for a New Integrable System

A new integrable system describing the process of self-induced transparency with spatial dispersion is analyzed from the viewpoint of inverse scattering transform. The coupled set of Gelfand–Levitan equation is established and solved for one soliton solutions. The explicit structure of the solutions are exhibited graphically.     

Do anticommutators give additional conditions on adiabatic time-dependent Hartree-Fock path?

Utilizing one-particle one-hole variations of ATDHF states by invoking commutators obtained from generators of complete set of coordinates and of momenta, the ATDHF equations were shown in an earlier work to yield the valley condition. In principle, variations of ATDHF states should also be exploited by using anticommutators involving the said generators. It is demonstrated here that owing to the canonicity condition relating the generators of coordinates and of momenta, use of anticommutators gives rise to exactly the same valley condition on the ATDHF path.     

Mathematical analysis of isobaric decay chain in alpha particle induced reactions

A detailed mathematical formalism is developed from the first principles, to separate out the fractional contributions of the cross-sectionσ _g andσ _p for the production of the two isobaric precursor nuclei- grand parent and parent, respectively, to the cross-sectionσ _d for the formulation of the residual nucleus of interest. The analytical work of separating out such contributions gives a meaningful picture to the comparison with the theoretical predictions of hybrid model, using the initial excition numbern ₀ = 4(4p0h).     

The photonic ring: Algorithms for optimized node arrangements

New applications such as the future university and research environment, medical imaging, and supercomputer interconnects indicate that the future end-user will need to operate at close to peak electronic processing speed, viz. a few Gigabits per second. By exploiting the unique properties of emerging lightwave technology, it is now possible to embed different logical structures over a given physical network topology. Regular multihop structures, for example, bus, ring, toroid, are attractive candidates for logical topologies since they use simple routing schemes, that require less processing time.     

Quasi-exact solvability of Dirac-Pauli equation and generalized Dirac oscillators

In this paper we demonstrate that neutral Dirac particles in external electric fields, which are equivalent to generalized Dirac oscillators, are physical examples of quasi-exactly solvable systems. Electric field configurations permitting quasi-exact solvability of the system based on the sl(2) symmetry are discussed separately in the spherical, cylindrical, and Cartesian coordinates. Some exactly solvable field configurations are also exhibited.     

A Heuristic Algorithm for P-Cycles Configuration in WDM Optical Networks

Aiming at minimizing spare capacity for optical WDM networks, we propose a new heuristic algorithm for preconfigured protection cycle (p-cycle) design. Numerical results show that the spare capacity obtained by our new algorithm is very close to the optimal solution.     

A note on equivariant Euler characteristic

We give a new equivariant cohomological characterization of the equivariant Euler characteristic of aG-simplicial set as defined by Brown. This implies in particular that the equivariant Euler characteristic is aG-homotopy invariant.     

Role of polyester resin on the epoxy matrix system

Interpenetrating polymer network (IPN) as a polymer blend matrix was prepared using different ratios of polyester (PE) to epoxy (E) resins. It was observed that 11.33 wt % PE in the blend provides maximum mechanical properties, particularly the modulus for the casting, and such a blend is referred to as “optimum casting” (OC). The density of the blends containing up to 11.33% PE, especially of OC, was found to have increased by the presence of PE in the E network significantly more than would have been estimated from the calculation based on the rule of additivity. The thermal expansion coefficient parameter (Δα_i) of the OC was found to be 2.68 × 10^?4K^?1. The scanning electron micrograph (SEM) of the fracture surface of OC only showed a glass-like smooth surface. The change in the mechanical properties due to the varying proportions of PE in the blend was studied critically on the basis of failure mechanisms and morphological features. The differential thermogravimetric analysis (DTGA) of OC indicated only one peak in spite of the presence of two resin constituents, whereas castings with an excess of PE in the blend showed multiple peaks. Interestingly, as far as the DTGA is concerned, a domain of seemingly OC origin was found to remain, even in the blends containing PE resin above its optimum level (> 11.33 wt %). ©1995 John Wiley & Sons, Inc.