Improving the performance of mechanical stirring in biogas plant by computational fluid dynamics (CFD)

Stirring of material in biogas plant needs to be done to provide desirable contact between microorganisms and substrate which can improve digestion process. In the present study, computational fluid dynamics (CFD) was used to determine a suitable mechanical stirrer for biogas plant and simulate the flow pattern. In order to select optimum design of impeller, three types of impeller including six-blade turbine, four-blade turbine and six-flat-blade disc turbine were evaluated. Simulations were undertaken utilizing Fluent 15.0 software with a multiple reference frame approach via standard k-ε turbulence model under steady-state conditions. According to the simulation results, six-blade turbine impeller is more appropriate than the two other impellers. The results further indicated that, this type of stirrer offers suitable mixing both at the center and on the lateral walls of the reactor, reducing dead spaces and improving mass and heat transfers inside the reactor

Predictors of Exam Cheating Among the High School Students: Role of Personality Characteristics, Sensation-Seeking, Locus of Control and Exam Anxiety

The research purpose is to evaluate the personality characteristics, sensation-seeking, a locus of control and exam anxiety as the predictors of exam cheating among the high school students in Ahvaz City. Hence, the research employed a correlation and predictive method. The sample comprised 79 students with cheating background and 78 students without cheating background in the high schools of Ahvaz City. The selection of the cheating group was done with the confirmation and agreement of at least three teachers in each class and the non-cheating students were also randomly selected from the same class. The employed tools included Zukerman scale of sensation-seeking, Nowicki-Strickland Scale of locus of control and Friedman test anxiety scale. The data were analyzed using the discriminant analysis method. The obtained results indicated that the linear combination of the research variables can predict students’ cheating in the exams in the high schools located in Ahvaz City. Moreover, findings indicated that sensation-seeking and consciousness are the predictors of high school student’s cheating

The effectiveness of Mindfulness Based on Cognitive Therapy (MBCT) on quality of life and optimism of adolescent pregnant women

Background: Pregnancy during adolescence causes a person to face many challenges, so that its contradiction with the adolescent's identity structure can have negative effects on her psychological dimension, especially on optimism and quality of life. Since the health of the pregnant mother is one of the health priorities of any country, the present study aimed to investigate the effectiveness of mindfulness (MBCT) on the quality of life and the optimism of adolescent pregnant mothers. Methods: The present study was performed as an interventional study with a pre-test-post-test design on 88 adolescent pregnant women referring to health centers in Ahvaz. Participants were divided into 44 groups of intervention and control. For the intervention group, 8 sessions of 90-minute mindfulness counseling were held weekly. The control group also received routine pregnancy care. Participants completed the LOT-R and SF-36 quality of life questionnaires before and after the intervention. Data were analyzed by SPSS26 software. Findings: There was a significant difference in the overall quality of life between the control and experimental groups before and after the intervention (p <0.001).&nbsp

The Effect of Mindfulness Training on Cognitive Flexibility in Sixth-grade Female Students

The study was conducted to determine the effect of mindfulness training on cognitive flexibility in sixth-grade female students. This research used a pretest-posttest study with control group. A multi-stage random sampling was used in 4 schools, among which 37 sixth-grade female students were randomly selected and assigned to two experimental (17 students) and control groups (20 students). Students in the experimental group participated in a mindfulness training course for 12 (120-minute) sessions for a month and a half. The study used Dennis and Vander Wal's Cognitive Flexibility Inventory (2010). The results of covariance analysis showed that there was a significant difference between the two groups in the scores of cognitive flexibility and due to the higher mean scores of the cognitive flexibility of the experimental group in the posttest (p> 0.05, p = 10.25), it can be stated that mindfulness training was effective in increasing students' cognitive flexibility