Graphene-coated polymer particles have attracted research interests due to their emerging applications derived from their controlled structure and morphology. To control the properties of graphene oxide (GO)-polystyrene (PS) composite particles, the adsorption time and instantaneous adsorption conditions were investigated by varying their mixing method. Polystyrene particles prepared by emulsion polymerization were modified to have positive surface charge by adsorption of polyethylene imine (PEI) on the surface of PS particles. GO prepared by the chemical exfoliation method had negative surface charge from the oxygenated groups. The adsorption of the negatively charged GOs onto the positively charged PS particles was successfully completed, and it was found that a longer adsorption time and a greater difference in the instantaneous relative concentration led PS-GO particles to have more homogeneously coated surfaces without aggregation.
The purpose of this study was to explore teachers' workload and its sources from teachers' perspective. Toward the purpose, interviews with and essays written by teachers were analyzed to interpret the meaning of teachers' workload and examine the relationship between their workload and social forces. The results indicated that teachers' workload could be fully understood when amount, intensity and nature of teachers' work were considered together. Among them the nature of work centered on non-educational affairs was perceived most serious problem by the teachers. However, most of the teachers felt helpless at their situation largely made by socio-structural factors including neoliberalism, bureaucracy and authoritarianism. Such a submissive reaction of teachers interacted with the forces to contribute to sustain their predicament.
The environmental problem is serious due to global warming In a concrete industry, the effort to reduce the problem of the destruction of environment arising from the indiscriminate use of limestone that is the raw material of cement and aggregate and the exhaustion of resources are continually emphasized In this research, the waste porcelain and waste glass that are the natural aggregate substitute materials were mixed and were applied. In addition, the magnesia phosphate composite and fly ash are mixed with a cement substitute material and the properties of the artificial stone was examined. Density, water absorption, rate of aggregate on the surface, compressive strength, and flexural strength were performed. As a result of the test, it is that waste glass with 60% and waste porcelain with 70% are the most excellent mix to produce the artificial stone.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.