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Votle betonske plošče – izzivi trajnosti
No full textPervious pavements are often considered as one of the solutions for urban areas due to their possibility to improve stormwater infiltration and reduce Urban Heat Island effect. Pervious concrete flags, as one type of pervious pavements, and the possibility of their application in cold climate were investigated within the presented research. Three types of mixtures (one reference mixture and two concrete mixtures containing fly ash as partial cement replacement), were tested on frost resistance with and without the presence of deicing salts. Samples were divided in two groups for each test, where for one group the drainage of flags was allowed and for the other group it was restrained. Mass of the samples and ultrasonic pulse velocity were measured during the cycles of freezing and thawing, while flexural and compressive strength of the samples were measured after the finalization of the tests. The results show that the tested pervious concrete flags show good frost resistance. When testing included saturating samples in salt solution, results show that the flags cannot endure more than 7 cycles of freezing and thawing if drainage is restrained. Samples that were allowed to drain showed decrease in flexural strength when compared to the reference samples, but showed similar or higher values of compressive strength.Prepustne prometne površine se pogosto obravnavajo kot ena od rešitev za urbana območja, saj lahko izboljšajo infiltracijo padavinske vode in zmanjšajo učinek mestnega toplotnega otoka. V okviru predstavljene raziskave so bile preiskane votle betonske plošče kot ena od vrst prepustnih prometnih površin in možnost njihove uporabe v hladnem podnebju. Tri vrste mešanic (ena referenčna mešanica in dve betonski mešanici, ki vsebujeta elektrofiltrski pepel kot delni nadomestek cementa) so bile preiskane glede odpornosti proti zmrzovanju z in brez prisotnosti soli za tajanje. Vzorci so bili za vsak preskus razdeljeni v dve skupini, pri čemer je bilo v eni skupini dreniranje plošč dovoljeno, v drugi pa omejeno. Masa vzorcev in hitrost ultrazvočnih impulzov sta bili izmerjeni med cikli zamrzovanja in tajanja, upogibna in tlačna trdnost vzorcev pa sta bili izmerjeni po končanih preskusih. Rezultati so pokazali, da imajo preskušene votle betonske plošče dobro zmrzlinsko odpornost. Pri testiranju, ki je vključevalo nasičenje vzorcev s solno raztopino, so rezultati pokazali, da plošče ne prenesejo več kot 7 ciklov zamrzovanja in tajanja, če je drenaža omejena. Pri vzorcih, ki so se drenirali, se je upogibna trdnost v primerjavi z referenčnimi vzorci zmanjšala, vendar so bile vrednosti tlačne trdnosti podobne ali višje
Computational Fluid Dynamics Analysis of Two-Phase Bioreactors with Smooth Periodic Constrictions
No full textIntroduction: In biochemical production, one of the key aspects of process
intensification is the transition from batch to continuous processing. In
multiphase reactor systems, for optimal performance, it is essential to ensure
proper fluidization and uniform distribution of solid particles. This is
particularly challenging as biochemical reaction rates are inherently slow,
requiring long residence times and efficient mixing. Achieving these
conditions simultaneously remains a key obstacle, limiting the widespread
adoption of continuous processes in the industry. To address these
limitations, innovative reactor designs with enhanced mixing at low flow
rates are currently researched, including oscillatory flow reactors. The
application of advanced computational tools, particularly Computational
Fluid Dynamics (CFD), has proven to be a strong asset in optimizing reactor
designs and process parameters..
Modeling and Optimization of Membrane Reactors for Production of Prebiotics
No full textIntroduction: Fructooligosaharides (FOS) are an established type of
prebiotics used in the supplement industry to improve the composition of
human gut microbiota. They can be produced using enzymatic
transfructosylation reaction of sucrose, which is conventionally done in batch
reactors. A major drawback of these conventional reactors is that FOS yields
and purity are low. This study analyses the improvement in FOS production
by using a membrane reactor under optimized process conditions. ..
Humane pluripotentne NT2/D1 ćelije imobilizovane u alginatnim mikrovlaknima: 3D sistem za testiranje uticaja bioaktivnih jedinjenja
No full textExtensive consumption of energy drinks (ED) and alcohol mixed with energy drinks (AmED) has become a prevalent practice among young people. Marked as enhancers of physical and mental performance due to their high levels of stimulant ingredients, such as caffeine and taurine, ED and AmED consumption can potentially cause adverse effects on the central nervous system (CNS) and cardiovascular system. Despite the role of stem cells in development and tissue renewal, studies examining the potential effects of consumption on these cells are lacking. In this study, we established a 3D system based on alginate microfibers to test the effects of bioactive compounds on human NT2/D1 embryonal carcinoma cells, a widely used malignant counterpart of human stem cells. We also assessed the effects of simulated acute ED and AmED consumption on the viability of pluripotent cells and evaluated the efficiency of mass transport to the cells using mathematical modeling. The obtained results show that the 3D system enables undisturbed growth and proliferation of NT2/D1 cells and uniform distribution of the tested compounds to all cells within the microfiber. Simulated acute ED and AmED consumption in the 3D culture did not affect the viability of NT2/D1 cells, compared to a 2D culture, where caffeine induced a significant, yet small, decrease in cell viability.Učestala konzumacija energetskih pića (engl. energy drinks-ED) i njihova kombinacija sa
alkoholom (engl. energy drinks mixed with alcohol-AmED) postala je rastući trend među
mladim ljudima. Proklamovano povećanje psihičkih i fizičkih performansi usled konzumiranja
ED, koji u svom sastavu sadrže visoke doze stimulativnih sastojka - kofeina i taurina, može
dovesti do neželjenih posledica, prvenstveno na funkcije centralnog nervnog sistema (CNS) i
kardiovaskularnog sistema. Uprkos ključnoj ulozi u razviću i adultnoj homeostazi, istraživanja
o potencijalnom efektu konzumacije ED i AmED na matične i progenitorske ćelije su
malobrojne. U radu je predstavljena optimizacija 3D model sistema na bazi alginatnih
mikrovlakana za testiranje uticaja bioaktivnih jedinjenja na humane NT2/D1 embrionalne
karcinomske ćelije, široko korišćeni model sistem kao pandan humanim matičnim ćelijama.
Ispitan je uticaj akutne konzumacije ED i AmED na vijabilnost ovih ćelija i uz pomoć
matematičkog modelovanja evaluirana je efikasnost prenosa mase ispitivanih komponenti
do imobilisanih ćelija. Dobijeni rezultati pokazuju da ovaj model sistem omogućava
optimalan rast i proliferaciju NT2/D1 pluripotentnih ćelija i uniformnu distribuciju ispitivanih
komponenti kroz alginatna mikrovlakna. Simulirana akutna konzumacija ED i AmED nije
uticala na vijabilnost NT2/D1 ćelija u 3D sistemu, za razliku od 2D modela gde je kofein doveo
do malog ali statistički značajnog pada vijabilnosti
Analytical techniques and source apportionment for heavy metal(loid)s in groundwater: A comprehensive review
No full textGroundwater contamination by heavy metal(loid)(HM) is a pervasive global issue threatening drinking water quality and public health. Effective mitigation requires robust analytical methodologies and predictive modeling frameworks. This review critically assesses cutting-edge instrumental techniques and source apportionment methods for detecting and understanding HM pollution in groundwater. Advanced laboratory techniques, exemplified by inductively coupled plasma mass spectrometry (ICP-MS), now achieve extraordinary sensitivity with detection limits in the sub-μg/L range and exhibit high precision (relative standard deviations between 2–3 %). Furthermore, hyphenated chromatography-spectrometry techniques, such as ion chromatography coupled to ICP-MS, facilitate detailed chemical speciation, effectively resolving redox-sensitive pairs such as Cr(III)/Cr(VI) and As(III)/As(V) at environmental concentrations (1–50 µg/L). Meanwhile, emerging electrochemical portable sensors enable on-site, real-time monitoring of groundwater quality. For source apportionment, multivariate statistical methods (including receptor models), isotopic fingerprinting, and machine learning algorithms have been increasingly integrated to disentangle complex mixtures of natural versus anthropogenic metal sources. By combining improved detection limits, enhanced speciation insights, and powerful data analytics and modeling tools, modern approaches support groundwater monitoring and pollution source tracking. Nevertheless, challenges such as matrix interferences, instability of metal species during sampling, and overlapping source signatures continue to complicate analysis, underscoring the need for integrated approaches that merge analytical innovation with data-driven tools to refine source attribution and ultimately ensure groundwater safety. Critical knowledge gaps are identified, including the need for more consistent monitoring approaches, closer integration of new analytical tools with field practice, and stronger policies to make sure scientific progress actually leads to better groundwater protection
Sustainable Poly (Methacrylic Acid)/Nanocellulose Hydrogel for Controlled Simultaneous Release of Active Substances for Skin Protection
No full textHydrogels based on poly (methacrylic acid), carboxymethyl cellulose, and nanocellulose fibers were successfully synthesized, characterized, and tested as topical carriers for the controlled release of hydrophobic resveratrol and hydrophilic acetyl glucosamine, active substances used in skin protection. Carrier composition was confirmed by Fourier-transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) revealed the pore size variations with alterations in the neutralization degree of methacrylic acid and changes in the pore-wall roughness caused by different mass fractions of nanocellulose. The neutralization degree of methacrylic acid had a substantial impact on the swelling behaviour, while only a slight change in swelling was caused by various contents of nanocellulose in hydrogels. Mechanical properties of the hydrogels accessed by compressive strength measurement at various percentages of strain were improved by the addition of nanocellulose. Hydrogels containing 0.5% nanocellulose achieved the highest compressive strength. The neutralization of methacrylic acid reduced the mechanical properties. Hydrogels with optimal properties showed outstanding potential in encapsulation, and controlled the simultaneous release of resveratrol and N-acetyl glucosamine. The different nature of the active compounds, however, affected the release kinetics and mechanism, as confirmed by the Korsmeyer–Peppas model
Analysis of Accredited Conformity Assessment Bodies in European Countries with Respect to Socio-Economic Indicators: A Multivariate Approach
No full textAkreditacija predstavlja jedan od četiri osnovna elementa infrastrukture kvaliteta. Tela koja podležu procesu akreditacije su laboratorije za ispitivanje, laboratorije za etaloniranje, medicinske laboratorije, kontrolna tela i tela za sertifikaciju proizvoda, sistema menadžmenta i osoba. Osnovni cilj ovog rada je ispitivanje korelacije između društveno-ekonomskih parametara i broja akreditovanih tela za ocenjivanje usaglašenosti u preko 30 država Evrope. Za ispitivanje korelacije korišćene su multivaricione statističke metode: Pirsonova korelaciona analiza, analiza glavnih komponenti i klasterska analiza. Dobijeni rezultati ukazali su da je najjača korelacija između bruto društvenih proizvoda i broja stanovnika sa brojem akreditovanih laboratorija za ispitivanje i etaloniranje, kao i tela za sertifikaciju proizvoda. Analizom glavnih komponenti dobijene su dve glavne komponente, dok je klasterska analiza izvršila grupisanje tela za ocenjivanje usaglašenosti u tri klastera i zemlje Evrope u pet klastera. Ova studija pokazala je da postoje velike sličnosti u sistemu akreditacija u Evropi.Accreditation represents one of the four fundamental elements of quality infrastructure. The bodies subject to the accreditation process include testing laboratories, calibration laboratories, medical laboratories, inspection bodies, and certification bodies for products, management systems, and persons. The main objective of this paper is to examine the correlation between socio-economic parameters and the number of accredited conformity assessment bodies in more than 30 European countries. To investigate the correlation, multivariate statistical methods were applied: Pearson correlation analysis, principal component analysis, and cluster analysis. The results indicated that the strongest correlation exists between gross domestic product and population size on the one hand, and the number of accredited testing and calibration laboratories as well as product certification bodies on the other. Principal component analysis yielded two main components, while cluster analysis grouped conformity assessment bodies into three clusters and European countries into five clusters. This study demonstrated that there are significant similarities in the accreditation system across Europe
Contribution to the understanding of the yellow tides phenomenon in the coastal waters of the southern Adriatic – Bay of Boka Kotorska
No full textAim: Research on the composition and abundance of zooplankton and phytoplankton was conducted during the yellow tide caused by dinoflagellate bloom in the Bay of Kotor.
Material and methods: This study analyses zooplankton and phytoplankton samples collected from three stations in the Bay of Kotor over two months during the summer of 2016/17. Zooplankton was collected with Nansen nets (100 and 150 µm), and phytoplankton with 5 litre Niskin bottles. Salinity and temperature were measured simultaneously with a CTD multisonde (Sea-Bird Electronics Inc., USA).
Main results: The Bay of Kotor is characterised by increased phytoplankton production compared to other bays within Boka Kotorska Bay complex, but the maximum values did not exceed 600,000 cells/L. During the study, elevated temperatures and eutrophication caused an explosive phytoplankton bloom, which turned the water yellow-red. Two species of dinoflagellates dominated: Prorocentrum scutellum and Prorocentrum micans. In the zooplankton, Penilia avirostris, Paracalanus parvus, Centropages kröyeri, Oithona nana, and Monotula subtilis were dominant. In the surface layer, affected by the bloom, C. kröyeri dominated with over 90%. O. nana dominated throughout the rest of the water column, all the way down to the bottom.
Conclusion: Intense warming of the Bay of Kotor, prior to heavy rains, led to high surface water temperatures reaching 29 ºC. After the rains and runoff from the land, large quantities of soil with mineralised faecal matter were introduced into the Bay, causing a sudden increase in organic salt deposits, followed by a phytoplankton bloom and disruption of the ecological balance. In the shallow part of the Bay, the entire plankton community degraded due to the abrupt development of Prorocentrum sp
Lignin in Water Purification: Enzymatic and Adsorption-Maintained Processes
No full textThe utilization of biocatalytic systems based on lignin in wastewater treatment and
bioremediation has emerged as a promising approach to address challenges associated with pollutant removal and water purification. Immobilization of biocatalysts
generally offers enhanced stability, reusability, and efficiency compared to freeenzymes. Due to that immobilized biocatalysts represent a viable option for various
treatment processes. The choice of support material is pivotal. It significantly
in uences the properties of the resulting biocatalytic system. Awide array of support
materials, including inorganic, organic, hybrid, and composite materials, can be
utilized to create stable and efficient platforms for biocatalysts. This book chapter
provides an overview of the application of enzymes, such as laccases and peroxidases, immobilized on lignin-based matrices in wastewater treatment. It focuses on
their role in degrading organic pollutants, such as dyes, phenols, and pharmaceuticals, and explores the design and usage of lignin-based matrices in adsorptionmaintained processes for removing heavy metals and organic pollutants from water
bodies. Various approaches in the design of lignin materials are discussed, highlighting their impact on enzyme performance and system effectiveness. Furthermore,
recent advancements and challenges in the field of development of functional
polymers from biorenewable sources, such as lignin and lignocellulosic biomass,
are addressed, along with potential future directions for research and application.
Overall, the use of biorenewable polymers holds a great promise for advancing
wastewater treatment technologies, offering environmentally friendly and sustainable solutions for water remediation
Radiotoxic and chemotoxic probabilistic risks from uranium, thorium, and potentially toxic elements in groundwater near coal-fired power plants
No full textGroundwater contamination near coal-fired power plants (CFPPs) poses a potential risk to human health. This study assessed groundwater uranium, thorium, and potentially toxic elements in the three CFPP areas in Serbia. While most elements complied with the World Health Organization (WHO) drinking water guidelines, exceedances were observed for As (18.2 %), Pb (36.4 %), Fe (51.5 %), and Mn (48.5 %), especially near ash ponds and waste storage sites, indicating significant anthropogenic influence. Human health risk was assessed using both deterministic and probabilistic approaches, including two-dimensional Monte Carlo simulation (2D MCS), which allowed for a more precise and more realistic estimation by accounting for both variability and uncertainty. According to the 2D MCS results, children near the Kolubara CFPP had the highest non-carcinogenic risk, with hazard index values ranging from 1.26 to 1.70. In contrast, adults in the same area faced the highest carcinogenic risk, with chemical incremental lifetime cancer risk between 1.59 × 10−4 and 2.08 × 10−4, and radiological excess lifetime cancer risk between 5.51 × 10−5 and 8.07 × 10−5. Multiple linear regression modeling determined population-related (exposure frequency, ingestion rate, and body weight) and environmental (As and Cr concentrations) criteria that could maintain health risks within acceptable ranges. These findings may support the development of targeted groundwater protection strategies