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The aim of the study was to investigate how Serbian native speaking preschool children comprehend perfective and imperfective aspect in comparison to adults. After watching animated movies with complete, incomplete and unstarted actions, the participants were asked questions with a perfective or imperfective verb form and responded by pointing to the event(s) that corresponded to each question. The results converged to a clear developmental trend in understanding of aspectual forms. The data indicate that the acquisition of perfective precedes the acquisition of imperfective: 3-year-olds typically understand only the meaning of perfective; most 5-year-olds have almost adult-like understanding of both aspectual forms, while 4-year-olds are a transitional group. Our results support the viewpoint that children’s and adults’ representations of this language category differ qualitatively, and we argue that mastering of aspect semantics is a longterm process that presupposes a certain level of cognitive and pragmatic development, and lasts throughout the preschool period. [ABSTRACT FROM AUTHOR]

Abstract: Sulfur concrete was prepared by using the following initial components: sand as an aggregate, modified sulfur binder, and alumina as a filler. Portland cement concrete was made of the same aggregate, cement and water. The durability of prepared concrete samples was tested in 10% solution of HCl as a function of immersion time. The changes in mechanical strength and mass of the samples were periodically measured. Sulfur concrete exhibited limited mechanical strength and mass loss, while physico-mechanical properties of Portland cement concrete regressed rapidly. The image analysis used for surface destruction monitoring, performed by Image Pro Plus Program for determination of damaged surface area and original surface area before acid resistance testing, showed the similar results. Based on the image analysis results, model for predicting the mechanical strength degradation during durability testing was presented. The fact that calculated and experimental strength values were not far apart proved the validity of the proposed model. [Copyright &y& Elsevier]