ABSTRACT. Our aim was to explore the use of practice theory as an approach to studying urban environmental stewardship. Urban environmental stewardship, or civic ecology practice, contributes to ecosystem services and community well-being and has been studied using social-ecological systems resilience, property rights, communities of practice, and governance frameworks. Practice theory, which previously has been applied in studies of consumer behaviors, adds a new perspective to urban stewardship research, focusing on how elements of a practice, such as competencies, meanings, and physical resource, together define the practice. We applied practice theory to eight different civic ecology practices, including oyster gardening in New York City, a civil society group engaged in litter cleanup in Iran, and village grove restoration in South Korea. Our analysis suggests that in applying practice theory to the civic ecology context, consideration should be given to social and communication competencies, how meanings can motivate volunteers and sustain practice, and the nature of the resource that is being stewarded. Future studies may want to focus on how practice elements interact within and vary across practices and may be used to more systematically analyze and share ideas among diverse civic ecology practices.

Social support and face-to-face learning may enhance outcomes for students who face barriers in accessing Massive Open Online Courses (MOOCs). In this study, we investigated how self-identified volunteer leaders guide and foster interactions among small groups of students who face technical and conceptual barriers in accessing MOOC content. Several months prior to the start of the MOOC (Environmental Education: Trans-disciplinary Approaches to Addressing Wicked Problems), we asked for volunteers among the registered students to lead groups for participants whose primary language was other than English and where limited Internet access, culture, or other barriers curtailed access to and understanding of course materials and pedagogy. Based on a survey and open-ended interviews (n=10), we found that group leaders were instrumental in overcoming barriers related to language, content, cultural ways of learning, access, and time. They also fostered cooperative learning strategies, which helped students acquire course content, and encouraged collaborative group projects leading to their groups adopting some features of online knowledge communities. We propose the term social learning MOOC (slMOOC) to capture a growing trend of incorporating collaborative learning strategies in xMOOCs.

In this article, metoclopramide tablet was thoroughly evaluated as an effective inhibitor for mild steel in 0.5 M sulfuric acid and 1 M hydrochloric acid solutions by different techniques (potentiodynamic polarization and electrochemical impedance spectroscopy [EIS]) and scanning electronic microscopy (SEM). The results revealed that the compound has a proper inhibiting effect at concentrations of 600 ppm for sulfuric acid and 300 ppm for hydrochloric acid solutions. The effect of temperature on the corrosion rate of alloy in the absence and presence of this drug was also studied. The EIS measurements revealed that by the addition of the inhibitor up to a certain concentration, the charge transfer resistance increases and the double layer capacitance decreases. The probe showed that the adsorption of the inhibitor on the alloy surface in both solutions follows Langmuir adsorption isotherm. This process is spontaneous and exothermic. The information obtained from SEM confirmed the formation of the protective layer on the surface of the sample after immersion in solutions containing the compound. K E Y W O R D Scorrosion inhibitor, electrochemical impedance spectroscopy, metoclopramide, mild steel

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Natural extracts have been widely used to protect metal materials from corrosion. Mild steel (MS) corrosion inhibition in 0.5 M sulfuric acid was investigated in the absence and presence of Thyme leaf extracts as an economical corrosion inhibitor. The effects of various concentrations and different temperatures on inhibitor efficacy were investigated. Using electrochemical impedance spectroscopy and polarization curves, the corrosion resistance of the alloy was also estimated. The polarization technique indicated that the Thyme extract is a mixed‐type inhibitor for MS in 0.5 M H2SO4. The obtained results revealed an excellent inhibition efficiency of 98% at 200 ppm of Thyme concentration. The thermodynamic parameters calculated, the effects of temperature, and the adsorption mechanism were also investigated, that suggested formation of monolayer inhibitor molecules (i.e. the Langmuir adsorption isotherm) on the metal surface. The ∆Gadso value calculated from the Langmuir adsorption isotherm plots for inhibitor indicated that it was adsorbed on the alloy surface via a physisorption mechanism. Additional studies on plant extracts as corrosion inhibitors on metals are needed to produce solutions for industrial purposes.

The inhibition behavior of metoprolol tablet on steel alloy (st37) in 1 M hydrochloric acid and 0.5 M sulfuric acid solutions were studied by three methods (potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electronic microscopy, SEM). The obtained parameters revealed that different amounts of metoprolol drug inhibited the corrosion of mild steel in the acid solutions of HCl and H 2 SO 4. The corrosion resistance of the alloy increased with the increase in the concentration of metoprolol up to 300 ppm but was reduced by increasing the temperature. The derived parameters from polarization curves indicated that the drug is a mixed type inhibitor. The results obtained from the different methods are consistent with each other. The adsorption of metoprolol was found to be physical, exothermic, and spontaneous, and also fitted the Langmuir adsorption model. SEM micrographs are in accordance with the adsorption performance of the tablet.

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