The University of Niš (Serbian: Универзитет у Нишу, romanized: Univerzitet u Nišu) is a public university in Serbia. It was founded in 1965 and consists of 13 faculties with 1,492 academic staff and around 20,500 students (as of 2018–19 school year). Since its founding, the university diploma has been acquired by more than 50,000 students, including 1,300 foreigners.It has a university library "Nikola Tesla"; the Faculty of Technology is located in Leskovac, Pedagogy Faculty in Vranje and Agriculture Faculty in Kruševac.
This study investigates a sustainable route for biodiesel production from waste plum kernel oil (PKO) using a heterogeneous, waste-derived catalyst (35% CaO supported on coal fly ash-derived zeolite), in the presence of a green deep eutectic solvent (DES), triethanolamine:menthol (TEA:M, 1:2 mol/mol), as a cosolvent. The catalyst exhibited a high specific surface area, developed porosity, and abundant strong basic sites, ensuring effective transesterification activity. PKO, characterized by low acid value (1.95 +/- 0.03 mg KOH/g) and high oleic acid content (73.8 +/- 2.5%), proved to be a suitable feedstock for biodiesel production. The incorporation of TEA:M DES into the reaction system significantly enhanced fatty acid methyl ester (FAME) formation by improving mass transfer during the initial reaction period. Transesterification was conducted at 60 degrees C under atmospheric pressure by varying the catalyst amount (2-10% based on oil mass), DES amount (1-9% based on oil mass), and methanolto-oil molar ratio (6:1-12:1 mol/mol). A maximum FAME content of 96.7% was achieved under optimized reaction conditions (8% catalyst, 5% DES, 6:1 methanol-to-oil ratio). Transesterification followed a pseudo-firstorder kinetics with rate constants of 0.032-0.152 min(-1) and an activation energy of 42.67 kJ/mol. The catalyst maintained high activity over five reuse cycles, with only a slight decrease in FAME content from 96.7 +/- 1.0% to 94.5 +/- 0.5%. Cost analysis confirmed process feasibility ((sic)1.24/kg), demonstrating the potential of integrating waste-derived catalysts with green cosolvents for sustainable biodiesel production and providing a promising pathway toward a circular economy.
This paper establishes exact expressions for the Drazin inverse of the modified tensor A−C*NDD*NB via the Einstein product, formulated using the Drazin inverse of A and the generalized Schur complement D−B*NAD*NC, providing a comprehensive generalization and unification of existing results in the literature for the case when the tensors are of order two. Furthermore, the findings reduce to the classical Sherman-Morrison-Woodbury formula in the special case of second-order tensors. Finally, we provide two examples to illustrate our new explicit expressions.
Industrial hemp (Cannabis sativa L.) production and the hemp-based industry are set for expansion. Hemp is cultivated for valuable fibers from stems and oil from seeds, used in various industrial applications. Recently, hemp has been grown for energy production due to its high biomass and seed yields. Hemp oil is suitable for biodiesel production through transesterification, while hemp biomass serves as a solid fuel or raw material for bioethanol, biohydrogen, and biogas production. This paper provides a comprehensive review of hemp seed and biomass pretreatment, oil extraction, and biofuel production methods. Pretreatment methods for hemp seed and biomass are largely unexplored, and innovative methods require detailed economic analysis before commercialization. Research on hemp oil extraction is sparse and lacks comparative analyses of different techniques regarding yield and quality. Advanced methods yield more oil in shorter times than conventional techniques. Advanced solvent extraction yields more oil than screw pressing and maceration but less than Soxhlet extraction. Transesterification of hemp oil for biodiesel typically uses base catalysts, either homogeneous or heterogeneous, but novel methods have yet to be applied. Other biofuels are produced by thermochemical (torrefaction, pyrolysis, gasification) and biological (fermentation, anaerobic digestion) processes. A comparative analysis of biofuel yields and primary energy recovery potentials of different hemp components is needed to optimize biomass utilization in bioenergy production. Despite the substantial benefits of hemp biofuel production, challenges such as legal and regulatory barriers, economic competition with high-value products, production costs, environmental trade-offs, technological advancement, and public perception need to be addressed.
Myasthenia gravis (MG) is a heterogeneous autoimmune neuromuscular disorder with distinct serological subtypes, including antibodies against acetylcholine receptors (AChRs), MuSK, and LRP4. Despite increasing recognition of these subtypes, clinical practice still lacks a standardized, subtype-specific approach to diagnosis, characterization, and management. Current treatment strategies are often applied uniformly, without fully accounting for differences in disease phenotype, prognosis, and therapeutic response among antibody-defined groups. This review provides a comprehensive overview of adult MG, focusing on the various autoantibody subtypes and their implications for pathogenesis, clinical features, diagnosis, and management. We highlight how combining serological findings with clinical subtyping can inform a more personalized approach to therapy and better align treatment decisions with disease biology. By emphasizing the clinical relevance of serological classification, this review aims to bridge the gap between immunopathological understanding and individualized patient care in MG.
This study analyzes trends in three temperature variables (average annual air temperature, maximum air temperature, and minimum air temperature) for 72 time series from 24 meteorological stations in Central Serbia, spanning from 1949 to 2018. Data was sourced from meteorological yearbooks on the website of the Republic Hydrometeorological Institute of Serbia. Three statistical approaches were used: trend equation, trend magnitude, and the non-parametric Mann-Kendall (MK) trend test. GIS was applied to visualize geospatial data distribution. The results indicate a temperature increase in 66 of the 72 time series, with the largest increase of 4.3 degrees C and the smallest of 0.2 degrees C. Temperature decreases were recorded in 6 time series, with the largest decrease of-0.5 degrees C. The MK trend test revealed a statistically significant positive trend in 53 time series. Geospatial analysis showed varying temperatures across the region, with average annual air temperatures ranging from 10.6 degrees C in Dimitrovgrad to 18.1 degrees C in Belgrade. These findings offer insights into climate change in Central Serbia, highlighting areas of temperature increase and decrease, and provide a foundation for future climate research and strategy development.
