Nanoporous Polyether Sulfone Membrane, Preparation and Characterization: Effect of Porosity and Mean Pore Size on Performance

Flat sheet membranes were prepared by phase inversion technique using polyether sulfone (PES) dissolved in dimethylacetamide (DMAc) with and without adding polyvinylpyrrolidone (PVP) or polyethyleneglycol (PEG). The characteristics of the prepared membranes were evaluated using Scanning Electron Microscope (SEM) images, Atomic Force Microscopy (AFM), and Optical Contact Angle (OCA) measurements, and porosity tests. The porosity test and SEM images show that increasing additives to a certain value increases the porosity of the membrane. Also, as the coagulation bath temperature is increased, the porosity of the membrane is increased. The roughness of the membrane is increased by increasing the additive concentration. The analysis of AFM images confirms the nanoporous structure of the prepared membranes, and that the membranes with appropriate pore size distribution can be prepared by the applied method. Permeability tests using single-layer membranes show that the direct relationship between porosity and the flux of pure water or salt solution is dominated by the effect of applied additive while the salt rejection shows an inverse relationship with the mean pore size regardless of the applied additive. The salt permeation flux is a function of total porosity while the salt rejection is a function of surface porosity. Pervaporation tests show that both permeation flux and enrichment factor depend on the total porosity of the support membrane

Developing a checklist for dental students\' clinical skills assessment in practical pediatric course compared with global rating method

Background and Aims: Selecting the appropriate education evaluation method and the effects of this choice according to different fields of medical sciences, is one of the current priorities of medical education. Therefore, the aim of this study was to design a checklist for evaluating the practical skills of dental students and to get compared with the global ranking method. Materials and Methods: A checklist was developed for the assessment of clinical skills of the practical pediatric course according to an action research method. 32 students were evaluated by the checklist method and 32 students were evaluated by the conventional global rating method (sampling was based on available sample).  Faculty staff and students’ satisfaction regarding the two methods were reported by a 6-scaled measure and statistically analyzed by Wilcoxon Signed Ranks test. The students' scores by the two methods were subjected to paired t test for comparison. Results: The students were more satisfied with the checklist method (P=0.003). The faculty staff considered a greater ability of the checklist method to differentiate between the students (P=0.03). However, in terms of ease of use and suitability, most faculty staff preferred the traditional method (P=0.02). In other cases, there were no significant differences in the views of students and faculty staff towards the two methods. Conclusion: In the present study, both Checklist and global rating methods were valuable for evaluation, although due to the greater satisfaction of students and faculty staff with the developed checklist method, the possibility of identifying the weak points leading to decreased scores and better assessment of capabilities, this checklist can be used for evaluation instead