The effects of particle size distribution on the settleability of CSOs pollutants

Over the past decades, flocculation and/or sedimentation processes have been adopted to remove pollutants from CSOs. It has been learned that major factors affecting settlement of pollutants are the particle size distribution, their settling velocities and their specific gravity. It is, therefore, a good idea to analyze the particle size distribution and settleability of CSOs pollutants in order to develop details in designing a process. Discussed in this study are pollutant characteristics of CSOs such as particle size distribution and settleability of pollutants. The power law function is applied and is found to be an effective and reliable index for expressing the particle size distribution of pollutants in CSOs. Based on the particle size spectrum analysis, the tendency toward settling and simultaneous flocculation-settling phenomenon of CSOs pollutants is described. Based on the regression analysis it is observed that the derived constants of curves representing settling velocity profile are proportional to the initial concentration of particles and to the beta-values of power law distributions. It is also revealed that the simultaneous flocculation-settling processes are effectively described by the changes of the average particle diameter and of the beta-values of power law distributions.

Cephalometric variables as predictors of Class II treatment outcome

Cephalometric analysis of skeletodental features is accepted as an integral part of orthodontic diagnosis and treatment planning. This assumes that diagnostic cephalometric variables affect prognosis and thus help reduce malocclusion severity, which is the aim of orthodontic treatment. The aim of this study was to assess the predictive value of 41 commonly used cephalometric parameters with regard to pretreatment severity and treatment outcomes. Pretreatment severity was assessed by using the Peer Assessment Rating (PAR) occlusal index, an instrument that has been shown to be valid and reliable. Treatment outcomes consisted of (1) posttreatment malocclusion severity (post-PAR), (2) relative improvement (percent PAR reduction), and (3) treatment duration. Complete records, including cephalograms, of 223 treated Class II cases were analyzed by means of separate multiple linear regression models. Each of the outcome variables and the pretreatment severity served as the respective dependent variables, and the cephalometric parameters served as the independent or predictor variables. The cephalometric parameters explained 39.2% of the pretreatment severity variance, 17. 9% of posttreatment severity variance, 15.7% of relative treatment improvement variance, and 20.0% of treatment duration variance.