We investigate the excitation behavior of a repulsive Impurity-doped quantum dot induced by the simultaneous oscillations of the Impurity coordinate and spatial stretch of the Impurity domain. We have considered repulsive Gaussian Impurity centers. The ratio of two oscillations ( h) has been exploited to understand the nature of the excitation rate. Indeed, it has been found that the said ratio could orchestrate the excitation in a most elegant way. In conjunction with the ratio, the dopant location also plays some important role towards modulating the excitation rate. The present study also indicates attainment of stabilization in the excitation rate as soon as h exceeds a threshold value irrespective of the dopant location. Moreover, prior to the onset of stabilization, we also envisage maximization/minimization in the excitation rate at some typical h values depending on the dopant location. The critical dissection of the characteristics of various Impurity parameters provides important insight into the physics underlying the excitation process.

We have studied the effect of Impurity on electronic properties of single-walled carbon nanotubes using Density Functional Theory. Electronic band structures and density of states of (4, 4) and (7, 0) carbon nanotubes in the presence of different amount of B and N impurities were calculated. It was found that these impurities have significant effect on the conductivity of carbon nanotubes. The metallic (4, 4) nanotube remains to be metallic after doping with B and N. The electronic properties of small gap semiconducting (7, 0) tube can extensively change in the presence of Impurity. Our results indicate that B-doped and N-doped (7, 0) carbon nanotubes can be p-type and n-type semiconductors, respectively.

Trinitrotoluene (TNT) is one of the most widely used compounds in civilian industries like mining, dyes, and photographic chemicals, etc. During the TNT production, some undesired nitrotoluenes are present. The use of vacuum technology has been effective in separating and purifying nitrotoluene impurities. One of the effective methods in purifying TNT compounds is the use of an ejector, which, by creating a vacuum as well as ultrasonic conditions, makes it possible to separate the impurities. Thus, the objective of the present research is to use a special design obtained from coding and optimization of the device geometry to remove and purify nitrotoluene compounds. The effect of different parameters (primary pressure on mass flow rate of primary and secondary flows, isentropic efficiency coefficients on mass flow rate of fluids, constant area section to throat cross section, exit diameter of primary nozzle to throat diameter, and primary fluid temperature) on ejector  performance was investigated. The CFD tool and COMSOL Multiphysics software 5.6 were used to simulate the ejector and to validate the data. In the second part of the simulation, DWSIM software was used to ensure that the use of these operating conditions is applied to purify nitrotoluene compounds. The results showed that the ejector at very low pressures and high temperatures could concentrate TNT in crude TNT (84 wt%) to 98.45 wt% in the final product.