Among the available methods of enamel strengthening, fluoride varnish (FV) treatment has relatively better results. On the other hand, cold plasma technology has shown promising capacities in sterilizing the environment, surface modification, and improving adhesion. Accordingly, this study aimed to increase the adhesion of FV to the enamel surface to prolong the enamel interaction with FV with subsequently increased fluoride uptake by enamel. Emphasizing that the change in adhesion is evidence-based and has not been explicitly measured. For this purpose, we randomly divided twenty bovine teeth into two groups A (consisting of four teeth) and B (composed of four subgroups, each containing four teeth). Samples of group A and one specimen of each subset B investigated the effect of using Helium-DBD (He-DBDJ), Argon (ArJ), and Air-DBD jet on the enamel surface. Other B specimens are devoted to studying the release of FV fluoride ions from processed enamel. Two diagnostic techniques, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), have been utilized to examine the samples' surface morphology and chemical analysis, respectively. Finally, the release of fluoride ions into distilled water was measured by an ion-selective electrode (ISE). SEM images showed that ArJ and Air-DBD significantly damaged enamel hexagonal structures, whereas, in the case of He-DBDJ, the hexagonal structures have only altered from convex to concave. EDX indicated an increase in calcium to phosphorus ratio and the amount of fluoride and sodium uptake on the enamel surface layer in the group processed with He-DBDJ plasma. The latter helps restore the damaged parts of the enamel. Analysis of fluoride released from the FV did not show a significant change owing to plasma processing (P ≤ 0.112). The combination of cold plasma and fluoride varnish treatment on the enamel surface might be considered as a more promising approach to increasing enamel resistance to tooth decay.

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Corn starch has limited applications due to its paste intolerance during heating, high shear processing, and low pH of foods. In this study, native corn (NC) starch is treated by both cold plasma and chemical cross‐linking to produce modified starch. The cross‐link ratio (CR), granule morphology, as well as other physicochemical properties of the modified starch are evaluated. The CR is 5.2% by plasma treatment, and it could be further increased up to 23.7% by the subsequent cross‐linking using adipic acid and acetic acid anhydride mixture. Modified granules have more cracks, pits, holes, and damages than NC ones. FTIR spectra's shows some new peaks after dual modification (1563 cm−1) and plasma treatment (1730 cm−1). The plasma and cross‐linking treatments cause a significant increase of swelling power for all the modified starches. Results of the present study indicate the possibilities of exploring cold plasma and cross‐linking treatments for starch modifications.

A nonlinear simulation of the E × B drifting electron laser (DEL) and the free-electron laser (FEL), in three dimensions, is presented for a prebunched electron beam to study efficiency enhancement. For the planar wiggler with flat pole faces, prebunching considerably shortens the saturation length, which favors the DEL compared to the FEL. Operation of the DEL with the planar wiggler with parabolic pole faces was not found to be possible due to the modulation of the E × B drift by the wiggler. However, simulation results of the FEL with this type of wiggler are reported.

A method of phase point trajectory (PPT) is presented to solve the Boltzmann transport equation (BTE), which makes it possible to study the time-dependent behaviors of the electron velocity distribution function (EVDF) of ionized gases. The important features of the PPT method are: (a) It is recurrence-free. (b) The governing equations on the phase point trajectories are quite similar to those governing particle dynamics in the particle in cell (PIC) simulation and therefore, the technique is easy to use. (c) It has a unique and cost-effective second-order interpolation scheme. (d) In the PPT method, the full EVDF is calculated (i.e., it is not expanded). In order to illustrate how the PPT method works, the BTE is simulated for argon gas under the influence of an external uniform electric field, and the following are examined as benchmark: (i) Collisionless behaviors of EVDF and (ii) the time-dependent behavior of swarm parameters and their equilibrium values in the presence of elastic and inelastic collisions. (iii) The role of each of the collision terms in the behavior of EVDF and electron density. Finally, it is shown that the results of the PPT simulation are in good agreement with the results of the known relevant simulation methods.