In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed.

Polymeric materials, due to their excellent physicochemical properties and versatility found applicability in multiples areas, including biomaterials used in tissue regeneration, prosthetics (hip, artificial valves), medical devices, controlled drug delivery systems, etc. Medical devices and their applications are very important in modern medicine and the need to develop new materials with improved properties or to improve the existent materials is increasing every day. Numerous reasearches are activated in this domain in order to obtain materials/surfaces that does not have drawbacks such as structural failure, calcifications, infections or thrombosis. One of the most used material is poly(vinylchloride) (PVC) due to its unique properties, availability and low cost. The most common method used for obtaining tubular devices that meet the requirements of medical use is the surface modification of polymers without changing their physical and mechanical properties, in bulk. PVC is a hydrophobic polymer and therefore many research studies were conducted in order to increase the hydrophilicity of the surface by chemical modification in order to improve biocompatibility, to enhance wettability, reduce friction or to make lubricious or antimicrobial coatings. Surface modification of PVC can be achieved by several strategies, in only one step or, in some cases, in two or more steps by applying several techniques consecutively to obtain the desired modification / performances. The most common processes used for modifying the surface of PVC devices are: plasma treatment, corona discharge, chemical grafting, electric discharge, vapour deposition of metals, flame treatment, direct chemical modification (oxidation, hydrolysis, etc.) or even some physical modification of the roughness of the surface.

For many years, surface has quality received a serious attention due to its influence on various mechanical properties. The main contribution made in this scientific paper is the performance of actual experiments, as well as the experimental processing obtained in order to develop a model for predicting the surface roughness based on the optimization of cutting parameters. The novelty of this paper is brought by the method of obtaining the regression equation of the surface roughness, resulted from a standard end-milling process (standard milling tools, standard milling parameters, recommended by the tool manufacturer, 3 axis CNC machine and standard vice), on aluminum alloy 7136 in temper T76511, through two statistical methods of data analysis. This material is used for the production of extruded parts and is poorly understood for the proposed line of research. This study’s aim is to determine the surface roughness equation obtained by the milling of aluminum alloy 7136 in two ways: using Taguchi′s experimental design once and the other, using the central composite design. The Taguchi method and the central composite design are used to develop an efficient mathematical model to predict the optimal level of certain processing parameters. Using ANOVA analysis, a comparative study of calculated and experimental surface roughness values is carried out. The initial characteristics (surface roughness) and the controlled factors (cutting speed, depth of cut and feed) are analyzed with the Minitab program. Finally, an analysis of the advantages and disadvantages of the two methods used is presented. This study has a great industrial application, since the main task of every manufacturer is to achieve a better quality of the final product with minimal processing time.