International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this study, the tribological behavior of new generation cast irons (SiNb and SiW) developed as an alternative to cast irons containing high silicon and molybdenum (SiMo) is investigated under dry friction conditions. All cast irons are produced by sand mold casting as Y blocks according to ASTM A536-84 standard and metallurgical characterization studies have revealed that they all have spheroidal graphite and dispersed carbides like Mo-rich M6C, Nb-rich MC and W-rich M6C type depending on the alloying element, within a ferritic matrix. Although no significant change is observed in the spherical morphology of graphite in cast iron matrices, a significant change is observed in the amount of graphite and image analysis studies reveal that the graphite content (area-%) in SiNb and SiW cast irons is 4,02 and 4,30, respectively, compared to SiMo cast iron (5,80). A significant change in the hardness of cast irons is also determined depending on the microstructural features; SiNb (228 ± 7 HV10) and SiW (218 ± 5 HV10) cast irons have higher hardness values compared to SiMo cast iron (192 ± 5 HV10). Cast irons and alumina ball as counterpart material are subjected to a tribological interaction for 150 m under dry friction conditions at a nominal load of 10 N and a ball sliding speed of 0.08 m/s and the findings indicate that (i) the coefficient of friction (CoF) decreases as the graphite content increases, with SiMo having the lowest CoF (0.023), followed by SiW (0.025), and SiNb showing the highest CoF (0.040), (ii) the specific wear rate increases as the hardness decreases, therefore, SiMo has the highest specific wear rate, whereas SiNb demonstrates the lowest specific wear rate and (iii) adhesive wear is the dominant wear mechanism for all ductile cast irons due to the presence of their ferritic matrix.

Lettuce is an important leafy vegetable for Albanians. It is mostly used as a fresh salad. There are several forms (species) of lettuce that are cultivated in Albania, but Albanian farmers cultivate and market mostly the farmer’s cultivars (landraces), which are cultivars adapted to the conditions of the country and to the farming practice of the farmer. The introduction of foreign lettuce species increases the risk of genetic erosion of the farmer’s cultivars. Through various projects, cultivars of the salad farmer have been collected and their seeds are stored in the country’s Genetic Bank. This study was undertaken to recognize the morphological characteristics, as well as to evaluate the genetic variation of these genotypes with the aim of increasing the effectiveness of their using in possible genetic improvement programs, as well as other studies. In the study, 10 accessions (farmer cultivars) collected in different areas of Albania and stored in the Genetic Bank were taken.

Albanian farmers have and continue to cultivate farmer’s bean cultivars because they are adapted to the country’s conditions and to the cultivation practice of the farmer who uses low levels of chemical fertilizers in beans. But, in the current conditions, the landraces are at risk of genetic erosion due to socio-economic changes. Therefore, our concern and obligation is to preserve the common bean farmer’s cultivars, not only to be cultivated but also to be used in genetic improvement programs. This was the aim of this study through which to know the genetic variation of the farmer’s cultivars in order to increase the effectiveness of the genetic improvement programs of this plant of great value to the people. In the study, 40 accessions (farmer’s cultivars) collected in the northeastern and eastern areas of Albania and stored in the Albanian Genetic Bank were taken.

In this paper, the results of the DTA-TGA, SEM-EDS, and FTIR analysis of the corn silk are presented. The DTA-TGA analysis shows that the decomposition of corn silk has several stages which are manifested with corresponding peaks on obtained DTA-TGA curves. SEM-EDS analysis was performed before and after the adsorption of copper ions. It has shown that untreated corn silk has a non-uniform structure, consisting of channels and cavities of irregular orientation, which facilitates the penetration of the water phase into the adsorbent structure, and incorporation of copper ions in the internal active sites. After the adsorption of Cu2+ ions, the structure becomes more compact, and uniform, as a result of the incorporation of copper ions into the molecular structure of the corn silk. FTIR analysis shows that ion exchange is not the dominant mechanism of binding copper ions to the active sites in the molecular structure of the corn silk, but also chemisorption and physical adsorption is present.