Faculty of Technology and Metallurgy

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    Electrochemical passivation of niobium in KOH solutions
    (CROATIAN CHEMICAL SOC, 2006-12)
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    Prusi, Abdurauf
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    Grcev, Toma
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    Arsov, Ljubomir
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    Photoelectrochemical Study of Anodically Formed Oxide Films on Niobium Surfaces
    (CROATIAN CHEMICAL SOC, 2010-07)
    The semi-conducting properties of electrochemically formed oxide films onto Nb surface in 1 M H(2)SO(4) have been studied by photo-electrochemical measurements. By cyclic voltammetry the I vs. E profile of active/passive transition of Nb electrode has been recorded in the potential region from -0.5 to 8 V (SCE). The photocurrent maximums, band gap energies and flat potentials of anodic oxide films formed by stepwise rising of anodic voltage from 10 to 100 V on Nb electrode have been determined. Using Raman spectroscopy the development of crystalline structure in the films with different resultant thickness has been analysed. The semi-conducting properties of niobium oxides with development of crystalline structure have been discussed in term of breakdown processes in the films. The thresholds of transition from amorphous to crystalline form of anodic oxide films depending of applied voltages and time of polarization have been determined.
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    TOWARDS SUSTAINABLE EXTRACTION OF OIL FROM APRICOT KERNELS
    (2026-02-12)
    Amiti, Belinda
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    Deep eutectic solvents (DES) are gaining attention as green alternatives to conventional volatile organic solvents for the extraction of natural products. Their ease of preparation from inexpensive, biodegradable components, along with low toxicity and tunable physicochemical properties, makes them promising candidates for designing eco-efficient extraction processes. In this work, four DES systems based on choline chloride (ChCl) as hydrogen bond acceptor and different hydrogen bond donors glycerol, lactic acid, acetic acid, and glucose were synthesized and evaluated as co-solvents with n-hexane for the ultrasonic-assisted extraction of oil from apricot kernels. The DESs were characterized in terms of pH, density (δ), viscosity (μ), and electrical conductivity (σ) to better understand how their physical properties influence extraction performance. Oil extraction experiments demonstrated that the DES composition and its physical properties have a marked impact on extraction efficiency. Under optimized ultrasonic conditions, the use of ChCl:AA (1:2) as a co-solvent with n-hexane yielded the highest oil recovery of 26.62%, surpassing pure n-hexane, which afforded only 24.10% under the same conditions. In contrast, ChCl:GLY (1:2), ChCl:LA (1:2), and ChCl:GLU (2:1) resulted in lower oil yields of 18.95%, 22.23%, and 13.26%, respectively. The superior performance of ChCl:AA is attributed to its combination of relatively low viscosity, and high conductivity, which collectively promote enhanced mass transfer, more efficient cell disruption, and improved solubilization of lipophilic components when assisted by ultrasonic cavitation. Overall, this study highlights the importance of tailoring the physicochemical properties of DES to maximize performance and demonstrates the potential of DES n-hexane systems as green, efficient, and scalable alternatives to conventional solvent based processes for the valorization of apricot kernel oil and other plant derived lipids.
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    Preformulation Characterization of Hydroxypropyl Cellulose Microparticles for Drug Delivery Applications:A Basis for Rational Design and Process Optimization
    (HDKI, 2025)
    Georgievska, Tamara
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    Trajkovic, Stefan
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    Stojanov, Darko
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    Pecova, Monika Stojanovska
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