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  • Author: Elena Diaconu x
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Abstract

Transport through liquid membranes of various chemical species is a viable method for different applications in analytical or technological domain. This paper presents the transport and separation results of two compounds of pharmaceutical importance: salicylic acid and aspirin, using bulk liquid membrane technique. We studied the effect of the feed source and receiving phase pH on the transport efficiency of the two compounds throught chloroform membrane. These results were correlated with speciation diagrams of salicylic acid and aspirin. The speciation diagrams shows that in these pH conditions, for aqueous phase of the membrane system, the two compounds are mostly undissociated form and therefore active for transport. In this system it can be achieve separation of the two compounds, salicylic acid and aspirin, using a suitable complexing agent in the feed source such as Fe3+. In this way salicylic acid forms an inactive complex structure for transport while aspirin crosses the membrane and it is recovered in a percentage of 80% in the receiving phase membrane system.

Abstract

Starting from the fact that the principles of agro-ecology become fundamental principles for the development of a green economy, especially in the context of current climate change, the effective capitalization of the ecological conditions of an agricultural area is one of the main objectives of agricultural science and practice. Identifying and formulating adaptive technological solutions can guide any producer to capitalize different climate and soil conditions. The sandy soils in Southern Oltenia offer less favourable ecological conditions, and the cultivation of watermelons is now profitable enough for such conditions. Growers are, however, interested in getting the most productive yields, early and profitable, even under the conditions of climate change. The current paper quantifies the grafting of watermelons in the conditions of the sandy soils of Dăbuleni, with poor soil supply, with meteorological drought phenomena and agricultural drought risk, in terms of quality and quantity of production under the climatic conditions in 2015-2017. The results, correlated with the climatic conditions, recommend the cultivation of grafted watermelons, offering the producers in the area a niche of ecological adaptation, ensuring the resistance of plants to abiotic, thermo-hydric stress factors, and improving the resistance to low temperatures, heat and drought.

Abstract

This paper aims to establish the interface conditions influence on the flexible pavement structures life. The methodology consists in using the interface constitutive model available in the Alizé calculation program to calculate the stresses and strains in the flexible pavement structures.

The design criteria related to limiting fatigue cracking of asphalt layers and permanent deformations at the subgrade level from the road bed are used to estimate the flexible pavement structures lifetime.

When calculating the critical stresses and strains, most mechanical design methods of the flexible pavement structures considers that the road layers at interfaces are perfect bonded or total unbonded.

Proper modeling of the interface binding condition is an important aspect in understanding the real behaviour of in-service flexible pavement structures.