The structure and diversity of epipelic diatoms and some physico-chemical features of the Akarc¸ay streams were studied in samples collected monthly from four sampling sites between March and December 2008. A total of 107 taxa of epipelic diatoms were identified. While Amphora veneta, A. pediculus, Cocconeis placentula, Cymatopleura solea, Cyclotella meneghiniana, Encyonema minutum, Nitzschia tubicola, Ulnaria ulna, and Sellaphora pupula were dominant upstream, N. palea was dominant with over 65% of total abundance downstream. According to canonical correspondence analysis analysis, BOD 5 , COD, TDS, pH, nutrients, and conductivity had the most significant effects on diatom community structure. N. palea was strongly and positively correlated with BOD 5 , COD, TDS, and nutrients. A. pediculus, Navicula cryptocephala, and S. pupula were positively correlated with pH , EC, TDS, and NO 3-N. We show that the species diversity values gradually decreased with increasing pollution downstream.

Background and Aim: The aim of this study is to evaluate the apical debris extrusion amounts and preparation times of four different nickel-titanium systems with a similar cross-section design—Mtwo, RECIPROC, RECIPROC blue, and VDW.ROTATE. Materials and Methods: Eighty human mandibular central incisors were divided into four equal groups (n = 20). The test apparatus was inserted into an assembly that provided root canal temperature. Preparation times were recorded using a stopwatch, and the amount of extruded debris was collected in pre-weighed Eppendorf tubes. After drying, the net amount was determined by subtracting the previously measured Eppendorf tube weights from the total weight. Results: The Mtwo had the largest amount of debris, but there was no significant difference among the other groups. The VDW.ROTATE completed the preparation in a significantly shorter time than the RECIPROC blue and Mtwo. Conclusion: Compared to other files, the Mtwo sequence produced significantly more debris and required significantly more time to complete the whole root canal preparation.