The effect of a generalized nonlinear incidence rate on the stochastic SIS epidemic model

In this paper, we aim to analyze the classical SIS epidemic model with a generalized force of infection (including nonmonotonic cases), where the transmission rate is perturbed by white noise. Using Feller's test for explosions, we prove that the disease dies out with probability one without any restriction on the model parameters.     

Study of various parameters influencing the fixation of metallic ions Cu2+, Zn2+, and Ni2+ at the catalytic Amberlyst-15 resin in the presence of alcohols

The ionic exchange behavior of Zn²⁺, Ni²⁺, and Cu²⁺ metallic ions on Amberlyst-15 commercial resin was studied as a function of resin solution contact time, initial concentration of metallic ions, nature of the solvent, and the amount of resin. The metallic ions were studied in ternary mixtures using both column and batch experiments. In addition, water, methanol, ethanol, and propan-2-ol were used as solvents for dissolving metallic ions. It was found that the resin behavior depends on the solvent nature and the metallic ion concentration. The analysis of solutions by atomic absorption spectrometry revealed that the affinity of the resin for the studied metallic ions followed the sequence Cu²⁺ > Ni²⁺ > Zn²⁺ in the case of an aqueous medium. Furthermore, uptake increased with increasing amount of resin. A better uptake was observed in the case of the 75:25 % water/methanol compositions when the column technique was used. For the batch technique, we noted a better uptake using 100 % water. The uptake rate decreased with an increase in the number of carbons for the 50 % water–50 % alcohol solvents. The acid–base properties of Amberlyst-15 commercial resin were studied by 2-propanol decomposition test. Propene and acetone are the main expected products and it is believed that they are formed through dehydration or dehydrogenation reaction on acid and base sites, respectively.     

Polymer complexes. Part XVI. Structural chemistry of poly-(5-vinylsalicylidene)aniline complexes

Transition Metal Chemistry - Poly(5-vinylsalicylidene)aniline homopolymer and polymer complexes of 5-vinylsalicylideneaniline with CuII, CoII, NiII, CdII and $? UO_{2}^{2+}$ have been...     

Improving sample preparation of gold-containing ores of the second and third groups for assay analysis

A procedure is proposed for the sample preparation of gold-containing ores of the second and third groups for assay analysis; it allows for an improvement in the accuracy of the results of analysis.     

Vibrational relaxation of CO2(00°1) and N2O(00°1) by NO

The far-from-resonance transfers and the de-excitation processes in CO₂-NO and N₂O-NO systems have been studied by measuring fluorescence decay rate constants of CO₂ or N₂O excited to the (00°1) level by laser radiation. The diagrams giving the variations of these rate constants versus the molar fraction of CO₂ or N₂O have been set out. From these diagrams, the relative importance of the V-V transfer and V-T de-excitation rate constants is discussed. The transfer rate constants have been calculated from a semiclassical theory in which the interaction potential is a sum of four atom-atom Morse potentials. The disagreement observed between calculated and experimental values probably results from the attractive multipolar forces which the theory does not take into account.     

Generalized Weber Problem with Rectangular Regions

The problem of locating one or more new facilities relative to a number of existing rectangular regions is treated for the case where the rectilinear norm is used. The new facilities are to be located such that the total weighted distance is minimized. If there is interfacility interaction among the new facilities, a gradient-free nonlinear search algorithm is utilized. Computational experience suggests that this algorithm is expedient even in the solution of large problems.     

Steiner's problem and fagnano's result on the sphere

This note describes the nature of optimal solutions for the spherical Steiner-Weber location problem for the case of unit weights and either 3 or 4 demand points (requireing 4 demand points to lie in an open hemisphere). Geometrically appealing results which are necessary conditions for optimum solutions and spherical analogs of known planar results are obtained.     

Reliable electron affinities of perfluorocyclopropane and perfluorocyclobutane from convergent ab initio computations

To resolve discrepancies concerning the magnitude of the electron affinities of perfluorocyclopropane and perfluorocyclobutane, quantum chemical calculations have been carried out with the MP2 and CCSD(T) methods in conjunction with augmented correlation consistent basis sets (aug-cc-pVX Z, X = D, T, Q). Though no experimental values have been found for perfluorocyclopropane, we estimate its electron affinity to be 0.17 eV (0.00 eV without zero-point vibrational energy corrections). In addition, determination of the electron affinity of perfluorocyclobutane (0.61 and 0.44 eV with and without zero-point vibrational energy corrections, respectively) is in good agreement with experimental values reported by Miller and co-workers (0.63 +/- 0.05 eV). This study also demonstrates that the widely prescribed B3LYP/DZP++ model chemistry for computing electron affinities does not correctly describe these systems.