Higher College of Technology

About: Higher College of Technology is a based out in . It is known for research contribution in the topics: Higher education & Tourism. The organization has 369 authors who have published 379 publications receiving 729 citations.

DFT investigation of solvent, substituent, and catalysis effects on the intramolecular Diels-Alder reaction

Abstract: In this study, we report on a DFT investigation of two intramolecular Diels-Alder furan reactions. Optimizations of the studied structures, TS and IRC calculations, were carried out at B3LYP/6-31G(d) level. We have studied the effect of substituent, solvent and Lewis acid catalyst on cyclization-retrocyclization equilibria, activation energies, and stability of the desired products. The analysis of orbital coefficients, IRC curves, and Wiberg indices have proved that both reactions are under orbital control. We have found that for the reaction I (2↔4 + 5), where R = H, the exo attack is favored by hydrogen bond interaction, while for R = t-Bu, the steric hindrance leads to the endo attack. For the reaction II (3 → 6 + 7), the t-Bu-substituted products are the most stable ones. At another level, we have found that it is recommended to use polar organic solvents as DMSO with Lewis acid catalyst BF3. The latest leads to accelerate the reaction II with stabilization of the desired products.

Exponential stability of the quasigeostrophic equation under random perturbations

Abstract: The quasigeostrophic model describes large scale and relatively slow fluid motion in geophysical flows. We investigate the quasigeostrophic model under random forcing and random boundary conditions. We first transform the model into a partial differential equation with random coefficients. Then we show that, under suitable conditions on the random forcing, random boundary conditions, viscosity, Ekman constant and Coriolis parameter, all quasigeostrophic motion approach a unique stationary state exponentially fast. This stationary state corresponds to a unique invariant Dirac measure.

W-shaped and other solitons in optical nanofibers

Abstract: The main objective of this study is to investigate W-shaped and other types of optical solitons in nano optical fibers. The medium is described by perturbed nonlinear Schrodinger equation with Kerr law nonlinearity. The study is carried out by means of three exotic soliton ansatzes. Consequently, different forms of W-shaped solitons are derived under specific conditions. It is found that the formation of W-shaped solitons depends on the balance between the self-steepening effect and the nonlinear dispersion. Due to some restrictions, W-shaped solitons experience a decay into bright or dark solitons. Besides, numerous types of soliton solutions that describe different structures of optical solitons are extracted. These structures include bright, dark, kink-dark, kink and anti-kink solitons. The existence conditions of all optical solitons are presented. The behaviours of optical solitons are illustrated graphically by selecting suitable values for the physical parameters.

An Ebola model with hyper-susceptibility

Abstract: The Ebola Virus Disease is a zoonosis whose reservoir is fruit bats among other primates. Once the virus enters a human population from its supposed zoonotic reservoir, it can then spread through contact with infected persons or their body fluids. The people that are most susceptible to infection are close relatives of infected persons, healthcare givers and those dealing with deceased persons. We classify these people as being hyper-Susceptible and develop a mathematical model to study the impact of hyper-Susceptibility on the dynamics of Ebola virus disease outbreak. The model is shown to have a globally stable disease-free equilibrium point whenever the basic reproduction number R 0 is less than unity. The model is also shown to exhibit forward bifurcation, which suggests the possibility of eradication through keeping R 0 below unity. Disease spread is also shown to be highly sensitive to contact rate, transmission probability, death rate and hyper-Susceptibility. Numerical simulation of the model is also done to confirm the analytical results established.