The most sustainable and cost-effective approach to enhance river water quality is by actively managing its self-purification. This study's aim is to explore potential management scenarios for enhancing the river's self-purification capacity. The QUAL2Kw model was used to simulate the water quality and self-purification capacity in Dez River in Iran. The model was calibrated and validated using recorded data of three monitoring stations along the river. Five parameters, namely DO, BOD, COD, NO3-N, and NH4-N were calculated and compared with field data. The Margin of Safety was presented and added to the value of each parameter for better water management and protection. Sensitivity analysis was conducted to identify the most influential parameters in water quality simulation for Dez River. The study presented and compared the self-purification capacity across six proposed scenarios for managing water quality. The results showed that the oxidation rate, nitrification rate, and denitrification rate were the most influential parameters in simulating water quality using QUAL2Kw. Among the scenarios considered, the fourth scenario, which included urban and industrial sewage point sources as diffuse sources, exhibited the highest level of self-purification, estimated at 2,246,170.01 kg/day. In all scenarios, the self-purification capacity for COD exceeded that of other parameters along the river, with the highest COD self-purification reaching approximately 167,034.9 kg/day.

Objective: The present study was conducted with the aim of effective school-based self-control skill training on increasing psychological hardiness and self-efficacy of male students of the first secondary level.Method: This research is a semi-experimental study with a pre-test-post-test design with a control group. The statistical population of the present study included male students of the first secondary school in Qom city, 30 students were selected using the available sampling method and divided into two groups of 15 people completely randomly. Students in the experimental group participated in 8 sessions of the school-based self-control training program, and the control group did not receive training. Before and after the implementation of the intervention, both groups were evaluated using the psychological hardiness scale of Lang and Goulet (2003) and the self-efficacy scale of children and adolescents (SEQ-C). The data was analyzed using spss-22 software and through repeated measures analysis of variance test.Findings: The results showed that school-based self-control skill training has a significant effect on increasing students' psychological hardiness and self-efficacy (P<0.01). Conclusion: The findings of the present study indicated that school-based self-control skill training can be an effective intervention in increasing psychological hardiness and self-efficacy in students.

Background and aim: Inadequate bond strength of resin cements to dentin appears to be a typical cause of failure in retention of fiber posts. In restoring endodontically treated teeth with fiber posts the cement-dentin interface is the weakest link. This study aims to compare the effect of self-etch and self-adhesive resin cements on shear bond strength of fiber posts to dentin.Materials and methods: This in vitro experimental study included 40 mandibular premolars with a single canal. All samples received standardized endodontic treatment after meeting the inclusion criteria. They were randomly divided into four groups and a post space was prepared in each sample. A size two Match post RTD fiber post was cemented into each sample using CoreCem (RTD) in group A, Panavia F2 (Kuraray) in group B, Bis Cem (Bisco) in group C and Maxcem Elite (Kerr) in group D as cementing agents. All samples were then cut into two pieces. Each specimen was loaded with equal force using a Universal Testing Machine. The load was applied from the apical to the coronal portion of each sample until fracture occurred. The mean shear bond strength for two each group was recorded and statistically analyzed with ANOVA (one way) and Dunnett’s tests using SPSS.Results: The mean shear bond strength was found to be as follows: Group A: (12.66 ±3.77) MPa Group B: (14.61±4.18) MPa Group C: (7.26±2.49) MPa Group D: (6.68±3.17) Mpa, Significant difference was demonstrated between shear bond strength of four groups (P=0.001). Mean bond strengths of resin cements in group A and B were not statistically different. Same results were shown when comparing cements in group C and D. However, cements in group A and B (self-etch) provided stronger bonds to dentin compared to group C and D (self-adhesive), the difference being statistically significant (P<0.05).Conclusion: The use of self-etch resin cements results in higher shear bond strength to dentin compared to self-adhesive resin cements.

Background and Objective: Knowledge of the process of change and the prediction of water quality parameters of the rivers provide the quantitative information needed to calculate the tolerable pollution load in the natural environment of the river, as well as a fuller understanding of the biological processes an environment. The main objective of this paper is to use the QUAL2Kw qualitative simulator model to model water quality in the Dyvandareh River and reduce river pollution by more adapting the amount of inputs of pollutants in different areas of the river with its ability to self-pollute. Methods: In this study, the process of changing the important parameters of the water quality of the Diwandreh River, such as dissolved oxygen (D0), biological oxygenation (CBOD), chemical oxygen demand (COD), acidity (pH), electrical conductivity (EC) and temperature, and Calculating the percentage of self-pollination of the river from the beginning of the branch before the connection of the tallar river to the decaying parameters of BOD and COD, and to predict their changes, the QUAL2Kw qualitative simulation model has been used. In order to calibrate the model, data from December 2008 were used. Due to the ability of the model for automatic calibration in this study, calibration was done both manually and effortlessly. In order to evaluate and validate the model results, AME and root mean square error (RMSE) were used.

Introduction There are two approaches for water quality standardization and monitoring the pollution loads discharged into the water bodies, like rivers and estuaries. In the conventional system of command and control, the monitoring organization focuses on limiting the concentrations of physicochemical parameters of water, such as dissolved oxygen (DO), biochemical oxidation demand (BOD), chemical oxidation demand (COD), total nitrogen (TN), total phosphorous (TP), total kjeldahl nitrogen (TKN), and etc in the effluents of point-sources. This framework is easy for monitoring and penalizing, particularly for industrial and domestic polluters with continuous annual discharge flow. However, it has several shortcomings. The main weakness is the inflexibility of water quality standards regarding the environmental conditions of rivers, their self purification and vulnerability potential, and the seasonal variations of water quality and quantity of rivers. Besides, the conventional approach neglects controlling the discharges of non-point sources (NPS), including agricultural activities, as they may not be continuous or precise in location for sampling. These faults are introduced as a reason of pollution accumulation and Eutrophication in surface waters. In the second approach termed as controlling ambient discharges, the water quality standards are determined in local scales regarding the environmental potential and conditions of rivers. Here, water quality monitoring is focused on the critical points in the river itself and limiting the pollution loads rather than concentrations in these stations. This approach in monitoring considers other issues like the self-purification potential of river, and the total pollution loads (TPL) discharged by both point and non-point sources upstream. However, there are some challenges that make this framework more complicated. 1) Finding a proper standardization and TPL in a multi-parameter framework, 2) waste load allocation (WLA) and fair sharing of penalties among polluters, and 3) uncertainties regarding the seasonal variations of emissions and the fluctuations in river water quality and quantity. In this research, a methodology is introduced regarding the ambient discharge framework to calculate an optimal multi-parameter WLA among emission sources. This intends to determine an allowable TPL in a river with high seasonal variations and challenges in the aquatic life. For this purpose, we chose Tajan River in northern Iran as the study area. This river has 51 km length with annual average water volume of 15 million m3. It ends to the Caspian Sea where the estuary currently encounters DO deficiency in some seasons and endangers the aquatic life. This may be due to the pollutions discharged from point and non-point sources, including paddy fields, pulp and paper industry and municipal effluents of Sari city with the rural areas upstream. Methodology In order to find a proper WLA and TPL, a simulation is carried out on Tajan River with 18 reaches by Qual2kw software with 100 times iteration for calibration. This simulation includes two steps. In the farming season (FS) of the study area, more than 5 m3/s of water is allocated for paddy fields that reduces one third of river overall flow at headwater. This lessens the remediation potential of river for diluting pollutions discharged particularly the nutrients concentrations exist in the drainage of NPS. Conversely, in non-farming seasons (NFS), DO profile and base-flow of river increases and environmental pollution limits to the point sources. Therefore, simulation is calibrated with respect to the sampling results in the first scenario of FS and later validated by other data in NFS. Regarding the fitness function and auto-calibration based on the genetic algorithm, the simulated model with 100 iterations presented 71% accuracy. For that, the water quality data sampled from three stations between 2014 and 2015 in the upper, middle and lower lands of river are used. Results Figure 1 illustrates DO deficiency of river in two periods. It is obvious that in FS, DO deficiency exceeds 2. 5 mg/L (for a DO saturation of 8. 5 mg/L) that endangers aquatic life in the last 15 km of river to the terminus point but this is rather normal in NFS. Besides, in FS the concentrations of nutrients like TN and TP respectively increases more than 5 and 1. 5 folds in comparison with NFS. It should be noted that about 40% of TN is made of TKN in FS that shows two points. First, chemical fertilizers are the main pollution origins of NPS discharges, and second, it may devour considerable amount of DO in the nitrification process. Therefore, NPS like agricultural activities are introduced as the main reason of seasonal pollutions. In addition, both nutrients and carbonaceous compounds are highlighted as influential parameters on DO reduction. Therefore, DO is assumed as the key factor in multi-parameter WLA and decision-making. Here, it is assumed that 5 mg/L should be met as the minimum limit of DO throughout a year even in the most polluted periods FS, while 6 mg/L must be met annually in average. The sensitivity analysis on the origins of pollutions showed that the self purification potential of river for nutrients reduction will not exceed 10%, but it easily reaches 50% for carbonaceous organic loads. This result adds up the significance of NPS pollution control in decision-making for WLA in river. Therefore, regarding the simulated pollution loads of the terminus point in FS and NFS, the annual TPL in WLA is determined in a way that DO profile responds to the assumed limits. As shown in Table 1, the maximum allowable loads of TN and COD are respectively considered 2500 tons/yr and 4500 tons/yr. TPL for other parameters like TKN, nitrate, and TP are respectively 500, 2000, and 250 tons/yr. By these limits, the local concentrations of pollutants can be set as the standard level for better monitoring. For TN, TP and COD the recommended monitoring concentrations are 5, 0. 5 and 9 mg/L, respectively. By these conditions, it is expected that DO remains on the assumed standard level as shown in Figure 2. Here, WLA is set on 45% removal of pollutions discharged by NPS. This value may reduce 34% of TN, 46% of TP and 14% of COD at the terminus point. Conclusion In this research a method in introduced with respect to the ambient-based framework for water quality monitoring to find TPL and consequently the annual average concentrations of main water quality parameters. In the case of Tajan River, it is realized that the estuary is highly sensitive to the seasonal variations of water quality and quantity. The main source of these variations is marked as the agricultural activities of paddy fields that recommended to be mainly focused for multi-parameter WLA and decision-making. For this purpose, it is also recommended that DO is selected as the key controlling index because it reflects the effects of both carbonaceous and nitrogenous compounds and is crucial for the aquatic life. Finally, with respect to the self purification potential of river, TPL and WLA are determined. This approach can be similarly used in other cases to find local standards for water quality monitoring.

As the Kor river water is applied for agricultural uses in Fars province and also urban, agricultural and industrial wastewater are poured to it, a study was carried out on variation of dissolved oxygen concentration and water quality parameters along the Kor river, from Band-e Amir to the Bakhtegan lake (specially in critical time) . Industrial pollution sources are located up the Band-e Air and also urban and agricultural pollutants are poured to the river through the Ahoochar drain. Therefore, 11 sampling stations were selected down the band-e Amir. Most of the selected stations are located in diversion barrages established for agricultural uses. In each station, two samples were taken for determination of dissolved oxygen, one sample for measurement of biochemical oxygen demand for seven days (BOD7) and the other for some parameters such as TDS, PH,… Then, dissolved oxygen content and its variation along the distance were studied and also effective factors in decrease and in create of it were calculated by means of Qualkor model which was compiled in visual basic. Results of such experiments are the presentation of oxygen sag curve which is applied for the Kor river in two separate situations (critical condition and under study condition). In this study, dissolved oxygen content along the distance was not decreased from 4 mg/L (standard Limit for aquatics), but in critical conditions, this amount was less than standard limit in all the stations except in the first station. Dissolved oxygen content reached zero between the stations 2 and 4, so aquatic life is confronted in danger.

Purpose: The present research was conducted to explain creativity, based on self-management and creative self-efficacy by mediating of educational engagement in elementary school students with learning Difficult. Method: The research method was a descriptive-correlation method with a path analysis design in the form of structural equations. The statistics society was included of students in 4th to 6th grads with learning problems that were engaged to educate in primary schools of Arak city in the academic year of 1400-1401, which were selected 200 boys’ and girls’ students (100 each gender) with learning problems as the research sample by using the purposeful sampling method. Data gathering tools were include Colorado Questionnaire, Shaffer's creativity questionnaire, Karwowski creative self-efficacy, Houghton and Neck's self-management, and Wilborn's educational engagement, which were completed by teachers and parents of students with learning Difficult. The collected data were analyzed by using Pearson's correlation coefficients and path way analysis in SPSS and AMOS software. From structural equations modeling method was used to investigate the research model fitness.  Results: The findings showed that the research model have an agreeable fitness. Also acquired coefficients between variables parameters showed that meaningful direct effect of self-management dimensions and creative self-efficacy on educational engagement and creativity. In this means, by increasing the self -management and creative self-efficacy, there is a positive change in the degree of educational engagement and creativity in students with learning problems. So, the relationships between the variables of the model drawn in this research were confirmed.

Background & Aim: The aims of this study were to assess the impact of dentofacial relationships and sex on: Self evaluation and self satisfaction in 12-15 years old students in Qazvin in 2003, and to determine the correlation between type of school and variables determining malocclusion with self evaluation and self satisfaction.Method &Materials: A cross - sectional study two stage - cluster sampling was carried out among 120 students (58 girls, 62 boys) aged 12 - 15 years who attended 4 guidance - schools (2 public, 2 private) in Qazvin in 2003. All samples were examined clinically and a questionnaire was used to assess their self evaluation and self satisfaction. Data were analyzed by the means on Chi - square and Fisher exact test.Results: Overjet, crowding and severe maxillary irregularity were significantly related to self evaluation. Overjet and severe mandibular irregularity were related to self satisfaction. No sex difference was found. Type of school was not a significant factor affecting self evaluation and self satisfaction. High level of self satisfaction has been found in the students. However, the majority of student had mid level of self evaluation.Conclusion: Overjet is the only variable significant in 12-15 year old students affecting both self evaluation and self satisfaction. Subjective esthetic measure should be incorporated to clinical esthetic criteria. Good communication between dentist and patient is important in analyzing and planning esthetic treatment according to individual needs and desires.