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Preparation of antibacterial electrospun scaffold for skin cells culture.
Bajsić, E.G. ; Veceric, M. ; Zdraveva, E. ; Mijović, B. ; Grgurić, T.H. ; Ujčić, Massimo ; Trcin, M.T. ; Slivac, I.
In this work the function and application of titanium dioxide as a filler in a composite system polycaprolactone/titanium dioxide (PCL/TiO2) was examined. Titanium dioxide was applied by ultrasonic bath on already electrospun PCL fibrous scaffold treated and non-treated with NaOH. A procedure of surface modification of the electrospun PCL fibrous scaffold was made to enhance the interaction of the surface with the TiO2 particles. The surface modification was performed using NaOH for the formation of carboxyl groups on the fibers' surfaces. The water contact angle was measured by goniometer to prove the change from hydrophobic to hydrophilic polymer surface. SEM was used to study the morphology structure of the electrospun PCL fibrous scaffold before and after NaOH treatment and introduction of TiO2. The content of TiO2 on the electrospun PCL fibrous scaffold was determined by TGA. After NaOH treatment the surface of the electrospun PCL fibrous scaffolds changed from hydrophobic to hydrophilic. SEM micrographs show that with the sonification of 30 min homogeneous TiO2 particles distribution was obtained, while after sonification of 60 min, the TiO2 particles tend to agglomerate. The modification of the scaffold surface with NaOH enhances the adhesion of the TiO2 filler. TG analysis show that longer treatment of the electrospun PCL fibrous scaffolds in the ultrasonic bath gives lower thermal stability. The time of 30 minutes in the ultrasonic bath is optimal to provide sufficient amount of the TiO2 particles on the electrospun PCL fibrous scaffold.
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Kinetic Modeling of the Catalytic Hydrogenation of Nitrile Esters to Amino Esters.
Lali, Farzad ; Stavárek, Petr ; Ujčić, Massimo ; Laube, Marek ; Devaux, J.-F. D. ; Dubois, J.-L. D.
The catalytic hydrogenation of nitrile esters to amino esters was studied.Amino-esters are alternative monomers to produce these polymers. The hydrogenation of nitrile ester was performed in a stirred tank reactor. The mixing of the fluids was carried out using a gas induction stirrer with a hollow shaft. An appropriate amount of ammonia has to be dissolved into the reaction mixture in order to avoid side or consecutive reactions, whereas the starting material nitrile ester was diluted by applying methyl-cyclohexane as solvent.The influence of the amount of dissolved ammonia and the hydrogen solubility in the reactants and in the chosen solvent were considered in this study. A reaction mechanism is proposed a mathematical model, which describes the proposed reaction mechanism of intermediate species and products was proposed for this hydrogenation reaction. The data were fitted using the least square method and the relevant kinetic rate constants were determined.
Plný tet: SKMBT_C22018100509340 - PDF
Plný text: content.csg - PDF
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