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  • Author: Domokos Biró x
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Abstract

The aim of the research was to examine the effect of different fertilizers on the floristic composition and biomass yield of the semi-natural grassland used as hayfield near Vlăhița locality (Harghita County, Romania) in order to improve its management. In the same time the qualitative structure of the studied grassland was evaluated after the first application of the fertilizers. The vegetation survey was made before mowing, and a total of 84 plant taxa were identified. The studied plant community belongs to the association Festuco-Agrostetum capillaris Horv. 1951. From the 31 fodder species, 13 had very good or good nutritional value. The qualitative structure analysis indicates that the vegetation has developed under moderate anthropogenic pressure. Beside the Euro-Asian elements the Circumpolar and the Cosmopolite elements were well represented. Many species with high tolerance for temperature, soil pH, and soil mineral nitrogen content were registered. After the first application of fertilizers in all treated plots the biodiversity increased compared to the control plot. Fertilized plots also had a significantly higher biomass yield than the control plot. All fertilizers reduced the proportion of the species with good nutritional value from the Poaceae family. Organic fertilizer affected positively the proportion of other plant families than Poaceae and Fabaceae. Long-term experiments are necessary to evaluate the response of the vegetation on treatment with organic fertilizer in order to optimize productivity of the hayfield and sustain species richness.

Abstract

The effective recycling of polymer materials remains unresolved to this day, and this has had a devastating effect on the environment. This study examines an alternative method to PET recycling that is the generation of polymer fibers and fiber mats for filtration applications. The electrospinning instrumentation used in this study had to be designed and built in order to carry out the research. We have managed to produce PET fibers with 200-600 nm diameter, and free-standing fiber mats that could potentially be used in filtration applications.

Abstract

The presence of a second reactive gas in the magnetron sputtering chamber makes the process much more complicated, and the process control much more difficult than in the case of a single reactive gas. Macroscopic models have been developed in order to explain the complex phenomena and to provide support for the process control. These models are able to explain the nonlinearities of the process and the strong coupling between the control channels.

This paper introduces a model created with the intention to of gaining a good grasp of the process, especially regarding the conditions necessary to obtain the required stoichiometry of the film deposited on the substrate. For this purpose, we modelled the formation of the desired ternary compound both directly from the available particle fluxes and from intermediary compounds. The surface of the substrate is divided into eight dynamically variable regions, covered by different compounds, each exposed to the streams of five types of particles.

We present the analytical model and provide simulation results in order to demonstrate its capability toof describeing the nonlinear phenomena, which that characterisze the two-gas sputtering process.