Dampening Effects of Perceived Teacher Enthusiasm on Class-Related Boredom in College Students: Longitudinal Mediation Effects of Perceived Task Value.

This study aims to explore the longitudinal mediation effects of college students' perceived task value (PTV) between perceived teacher enthusiasm (PTE) and class-related boredom (CB). We conducted a longitudinal survey among college students from five colleges at the second (T1), sixth (T2), tenth (T3), and fourteenth week (T4) in a semester, and overall 1,371 students completed all the measurements. In the survey, a battery of questionnaires was used to measure the students' PTE, perception of task difficulty, perception of task value, and CB. At T1, boredom proneness was measured as a control variable. Analysis of the longitudinal data showed that after controlling for the effects of boredom proneness and perceived task difficulty, students' PTE was a significant predictor of CB, and students' PTV played a significant mediating role in this causation relationship. The study supported the importance of the control-value theory in explaining the mitigating effect of students' PTE on CB, especially highlighting the role of PTV.

[Research on low-level Hg(II) removal from water by the heavy metal capturing agent].

Treatment of mercury containing wastewater using conventional approach is considered to be difficult to bring down its concentration to meet the discharge standard. In this study, we utilized dithiocarbamate (DTCR-2), 2,4,6-trimercaptotriazine(TMT-18B), Na2S and Ca(OH)2+ as the advanced treatment agents to remove low-level Hg2+ from water. Due to its better treatment effect, DTCR-2 was finally chosen as the most ideal option. The influence of pH value, dosage of DTCR-2, reaction time, initial Hg2+ concentration as well as other heavy metal ions on the Hg2+ removal were studied. The results showed that DTCR-2 had high removal efficiency under the following conditions: 100 microg x L(-1) of initial Hg2+ concentration, pH 8.0, 1.0 times stoichiometric ratio of DTCR-2 dosage and 10 min of reaction time, leading to 41.36 microg x L(-1) of residual Hg2+ concentration which was below the national discharge standard (50 microg x L(-1)). Moreover, three heavy metal ions including Cd2+, Pb2+ and Cu2+, inhibited the DTCR-2 capturing capacity towards Hg2+ and the inhibition effects followed this order: Cu2+ > Pb2+ > Cd2+, while Zn2+ promoted the Hg2+ removal. From this study, we could provide theoretical support for process design to deal with wastewater containing low mercury concentration using DTCR-2.