8639 research outputs found
Sort by
Periodically Constricted Oscillatory Flow Reactor Design for Enzymatic Production of Emerging Prebiotics from Sunflower Meal
No full textWith the increase in production demands, lignocellulosic waste generated from
food industry has become a feedstock of interest for obtaining value-added
products through various upcycling methods. Emerging prebiotics represent a
class of food additives which can be derived from lignocellulose, with
xylooligosaccharides as one of the most promising representatives with various
positive effects on human health. However, traditional methods for prebiotic
production often rely on harmful chemicals and can suffer from poor product
quality due to toxic by-product formation. Moreover, specialized corrosion-resistant
equipment for high temperature processing is often required. Most commonly,
lignocellulosic biomass is treated in stirred tank bioreactors operating in batch
mode, while (semi)continuous processing and other reactor configurations remain
less prevalent. In this work, a periodically constricted oscillatory flow reactor was
designed for semi-continuous prebiotic production from sunflower residue. The
modular meso-scale reactor was manufactured via 3D printing and tested for
multiphase processing by adjusting the oscillatory flow parameters to achieve a
uniform distribution of biomass particles in the system. Subsequently, the reactor
was benchmarked against the traditional batch system for simultaneous
enzymatic hydrolysis and solid-liquid extraction of prebiotic oligosaccharides from
pretreated sunflower meal. The adopted pretreatment method aligns with the
biorefinery concept and consists of alcohol extraction of polyphenols, followed by
protein hydrolysis. The proposed reactor design has shown potential for bioprocess
intensification by enabling semi-continuous operation in multiple stages of the
green and sustainable enzymatic process for sunflower meal valorization
Application of Low-Cost Air Quality Monitoring System in Educational Facilities in Belgrade, Serbia
No full textIndoor and outdoor air quality in school environments varies significantly with respect to particulate matter (PM) concentrations, carbon dioxide (CO2) levels, and microclimatic conditions, all of which have a direct impact on the health, well-being, and performance of both students and staff. This study reports the findings of a monitoring campaign focused on PM10 and PM2.5 concentrations in two schools located in the urban area of Belgrade, Serbia. Measurements were carried out using low-cost sensor devices positioned in classrooms and in the surrounding outdoor environment. The PM concentration data were corrected through collocation with reference-grade automatic analyzers (Grimm EDM 180) from the National Air Quality Monitoring Network (NAQMN). During the winter season, the indoor-to-outdoor (I/O) concentration ratio for classrooms ranged between 0.7 and 0.8, indicating that indoor PM levels were generally lower than outdoor levels—likely a result of limited ventilation and reduced particle infiltration from outdoor sources. Conversely, in the summer season, the average I/O ratio typically exceeded 1.0 (ranging from 1.3 to 1.5), pointing to a more pronounced influence of indoor sources, such as occupant activities, resuspension of settled dust, and insufficient air exchange. Importantly, in over 60% of the measurements conducted during the summer period, indoor PM concentrations surpassed those outdoors, underscoring the critical need to address indoor emission sources and implement effective ventilation strategies, particularly during warmer months
Field Responsive Swelling of Poly(Methacrylic Acid) Hydrogel—Isothermal Kinetic Analysis
No full textExternally governed hydrogel swelling is a highly convenient yet inherently challenging process, as it requires both responsive materials and appropriately tuned external stimuli. In this work, for the first time, the influence of simultaneous action of external physical fields—ultrasound (US) and microwave heating (MW), combined with cooling—on the isothermal swelling kinetics of poly(methacrylic acid) (PMAA) hydrogel was investigated and compared with swelling under conventional thermal heating (TH) under isothermal conditions. Swelling kinetics were monitored over a temperature range of 248–318 K, under simultaneous cooling with either US, MW, or TH. The well-established Peppas model was used to determine swelling kinetics parameters, revealing a significant acceleration in the swelling process under MW (up to 48.8 times at 313 K), as well as different water penetrating mechanisms (non-Fickian diffusion) compared to TH and US (Super-case II). Additionally, it was demonstrated that the swelling conversion curves could be mathematically described using a “shrinking boundary surfaces” model. Isothermal swelling constants and the corresponding kinetic parameters (activation energy Ea and pre-exponential factor ln A) were calculated. The results confirmed that external physical fields significantly influence the thermal activation and swelling behavior of PMAA xerogels, offering insight into field-responsive transport processes in hydrogel networks
Structural alterations of fly ash-based geopolymers caused by cesium immobilization and leaching
No full textThis study investigates the effects of 2 and 5 wt% Cs additions on the setting time, compressive strength, and structure of fly ash-based geopolymers, along with the impact of Cs leaching in deionized water, following the ANSI/ANS-16.1–2003 standard over 90 days. Structural changes were analyzed using BET/BJH, XRD, ATR-FTIR, TGA/DTG, SEM/EDS, and 29Si MAS NMR. The addition of Cs prolonged the setting time, for 33 % for 2 wt% Cs and 61 % for 5 wt% Cs, indicating slower condensation reactions, and promoted the formation of an Al-rich aluminosilicate gel, suggesting a higher extent of the reaction. After five days leaching, the fraction of Al-rich units was reduced, with no significant effect on compressive strength. Diffusion was the initial leaching mechanism, which transitioned to depletion at a later stage. The implementation of 29Si MAS NMR in conjunction with other analytical methodologies has enabled the elucidation of the impact of Cs on the geopolymer structure and clarifies the mechanisms behind its immobilization and structural changes during leaching. High values of leachability index (∼10) and good mechanical performances of fly-ash geopolymers suggest that they are a cost-effective and sustainable solution for safely storing nuclear waste containing Cs
Hybrid 3D-printed scaffolds containing multi-doped mesoporous bioactive glass as drug-releasing components for bone regeneration
No full textOngoing efforts focus on optimizing the microemulsion-assisted sol–gel (ME-SG) process to
produce ion-doped bioactive glass particles with tunable structural, physicochemical, and
biological properties, offering excellent potential for drug loading, controlled release, and
integration into scaffolds for regenerative medicine. 3D-printing via mask-stereolithography
(mSLA) enables fabrication of scaffolds with precise geometry and internal architecture but
requires rapidly crosslinking resins. Incorporating ceramic particles affects resin viscosity and
photopolymerization behavior, making tailored composite formulations essential for
successful mSLA scaffold processing. In this study, multi-doped MBG particles (70SiO₂
20CaO–3MgO–5SrO–1CuO–1ZnO, mol.%) were synthesized via a modified ME-SG method
via ultrasound and successfully loaded with ciprofloxacin. Upon characterization, the particles
were incorporated into a photopolymerizable resin containing polyethylene glycol diacrylate,
methacrylic acid, and gelatin, and used to 3D print macroporous scaffolds via mSLA. The
scaffolds were further modified with chitosan/MBG/ciprofloxacin coatings to modulate
mechanical and antimicrobial properties. Spherical MBG particles (~300 nm) with confirmed
dopant incorporation and an amorphous, mesoporous structure with high specific surface area
were obtained. Biocompatibility tests showed high cell viability, low apoptosis, and minimal
necrosis, while ciprofloxacin-loaded MBGs exhibited sustained drug release, and complete
inhibition of Staphylococcus aureus growth. Incorporation of MBGs in the polymer resin
increased surface roughness of 3D-printed scaffolds. Furthermore, scaffold coatings
influenced porosity, mechanical and antibacterial properties, with chitosan/MBG and
chitosan/MBG/ciprofloxacin coatings demonstrating strong antimicrobial effects against
Staphylococcus aureus. Overall, these results demonstrate that multi-doped MBG particles can
be effectively integrated into 3D-printed scaffolds, providing tunable physicochemical,
biological, and antibacterial properties, making them promising candidates for bone tissue
engineering and drug delivery
Утицај електростатичких и дисперзионих интеракција на кристалну структуру и реактивност: пример фенитоина и његових деривата
No full textHydantoin derivatives represent a versatile class of heterocycles,
known for their pharmacological properties. Because drug efficacy often depends on the fine-tuning of weak intermolecular (non-covalent) interactions, analysis of the crystal structure of a drug molecule is important, as it enables deciphering its interaction profile. In this study, the crystal packing of phenytoin and
its selected derivatives were examined through dimeric motifs with different recognition modes using force-field calculations and a density functional theory
(DFT) approach. The relatively polar ethoxyacetyl group at the N3 position of
the hydantoin ring, capable of forming hydrogen bonds, enhances the contribution of electrostatic and polar components to the total interaction energy. In
contrast, the long alkyl chain promotes hydrophobic contacts, leading to dispersion forces dominating over electrostatic interactions. The reactivity of phenytoin and its derivatives were further evaluated by examining the influence of
these substituents using conceptual density functional theory (CDFT) descriptors. These findings demonstrate that substituents significantly affect crystal
packing and the balance of non-covalent interactions, providing valuable insights
for optimizing molecular recognition and drug–target interactions in the design
of new therapeutic agents.Деривати хидантоина представљају разноврсну класу хетероцикличних једињења,
позната по својим фармаколошким својствима. Будући да ефикасност лека често зависи
од финог подешавања слабих међумолекулских (нековалентних) интеракција, проучавање његове кристалне структуре је значајно јер омогућава разумевање његовог интеракцијског профила. У овој студији испитано је кристално паковање фенитоина и одабраних
деривата анализом димера и различитих начина молекулског препознавања, коришћењем прорачуна заснованих на пољу сила (force-field) и теорији функционала густине
(DFT). Релативно поларна етоксикарбонилметил-група у положају N3 хидантоинског
прстена, са могућношћу успостављања водоничних веза, појачава допринос електростатичких и поларних компоненти укупној енергији интеракције. Супротно њој, дугачка
алкил група подстиче успостављање хидрофобних контакта, услед чега дисперзионе силе
постају доминантне у односу на електростатичке интеракције. Реактивност фенитоина и
његових деривата додатно је испитана коришћењем дескриптора концептуалне теорије
функционала густине (CDFT). Резултати показују да супституенти значајно утичу на
изградњу кристалног паковања и природу нековалентних интеракција, пружајући притом
значајан увид за разумевање молекулског препознавања и интеракција молекула лека са
циљним местима што даље доприноси дизајнирању нових терапијских агенаса
Denture base poly(methyl methacrylate) reinforced with SrTiO3/Y2O3: Structural, morphological and mechanical analysis
No full textThis study presented the use of SrTiO3/Y2O3 nanoparticles for the reinforcement of dental poly(methyl methacrylate) (PMMA) to enhance its mechanical properties important for everyday use of denture base materials. The average crystallite size of prepared nanoparticles was 19.9 nm. The influence of 0.5, 1.0, and 1.5 wt% SrTiO3/Y2O3 loading on absorbed impact energy, microhardness and tensile properties was investigated. Scanning electron microscopy of the composite fracture surface revealed multiple toughening mechanisms, with agglomerates directly included in the crack pinning, indicating improvement in mechanical performance. Dynamic mechanical analysis proved that agglomerates improved the elastic behavior of PMMA and confirmed the absence of a residual monomer. After the incorporation of SrTiO3/Y2O3, the mechanical properties of composites showed a high increase compared to neat PMMA. The optimal concentration of nanoparticles was 1 wt%, for which the microhardness, modulus of elasticity, and absorbed impact energy were higher by 218.4%, 65.8% and 135.6%, respectively. With such a high increase, this research showed that SrTiO3/Y2O3 represents an efficient filler which use does not have to be limited to dental materials. Highlights: SrTiO3/Y2O3 hybrid nanoparticles were prepared. PMMA-SrTiO3/Y2O3 composite showed increase in impact resistance up to 135.4%. Elastic behavior of PMMA was improved. With 1 wt% of SrTiO3/Y2O3, microhardness increased by 218.4%
Protein Stacking on the APTES-Functionalized Pyrochlore Bi2Ru2O7 Clusters for Ultrasensitive and Selective Immunosensing
No full textWith their unique physicochemical properties, such as metallic-like conductivity, favorable (electro)catalytic properties, electrochemical stability, and ease of functionalization, pyrochlores have found applications in various fields such as solid oxide fuel cells, batteries, thick film resistors, and temperature sensors; however, there are no reports on their application in electrochemical immunosensing. In this study, we exploited the (electro)catalytic nature and stability of the pyrochlore Bi2Ru2O7 clusters silanized with (3-aminopropyl)triethoxysilane (APTES) to demonstrate their potential for the effective stacking of functional proteins. Characterization of the clusters by XPS disclosed a dual environment of Bi, also indicating the presence of Bi2O3 alongside APTES-Bi2Ru2O7 clusters and, importantly, the predominant involvement of pyrochlore moieties in subsequent protein stacking. After stacking protein A and antibodies, the immunosensor revealed a nearly interference-free operation, high sensitivity, a detection limit of 118 fM SARS-CoV-2 spike protein, and operation in a wide examined concentration range of 10−5−10−1 μg mL−1 with an r2 of 0.98. In combination with a short incubation time of 30 min, the pyrochlore-based immunosensor provides a solid platform for future point-of-need applications
Influencing factors of groundwater 238U, 232Th, 40K, and rare earth element contamination: Insights from the two-dimensional Monte Carlo simulation of radiological risks
No full textIonizing radiation from naturally occurring radioactive materials (NORM) can pose significant health risks to humans, particularly when contaminating groundwater. As a vital resource, groundwater is essential for drinking, irrigation, and industrial processes in many regions worldwide. Therefore, this study developed a comprehensive and innovative method for groundwater source-specific radiological risk assessment, integrating multivariate statistical analysis, the two-dimensional Monte Carlo simulation (2D MCS), and a geographic information system (GIS) for mapping. Groundwater samples from an agricultural region were analyzed for radionuclides, including 238U, 232Th, and 40K, alongside sixteen rare earth elements (REE). Using the positive matrix factorization model, three pollution sources were identified: geogenic processes, weathering of REE-rich rocks, and agricultural activities. The results of source-specific radiological risk assessment revealed that adults were more vulnerable to radiological risk than children, and agricultural activities as the dominant contributor to risks. It was concluded that exposure frequency (EF), ingestion rate (IR), and 40K concentration were the exposure parameters with the greatest impact on radiological risk. Modeling these parameters established their critical values as 190 days/year, 2 L/day, and 415 ng/L, respectively, to ensure that the radiological risk for adults remains within the safety limit. Additionally, the incorporation of the 2D MCS into the risk assessment process significantly enhanced the accuracy and precision of the results, in comparison with the deterministic and one-dimensional Monte Carlo simulation (1D MCS) models. This research provides practical guidance for the sustainable management of water resources and presents an innovative methodology that can be applied to similar regions globally
The method of preparation of bio-based unsaturated polyester resin reinforced with modified nanocellulose fibers
No full textPredmetni pronalazak se odnosi na metodu pripreme nezasićene poliesterske smole (NPS) na bazi sirovina dobijenih iz bioobnovljivih izvora, ojačane modifikovanim vlaknima nanoceluloze. Metoda pripreme obuhvata sledeće korake: (1) sinteza predpolimera reakcijom polikondenzacije upotrebom nezasićene i zasićene dikiseline kao i glikola, kao polaznih monomera; (2) priprema resuspenzije vlakana nanoceluloze u acetonu i njihova modifikacija dimetil itakonatom gde se dimetil itakonat koristi kao reagens i kao rastvarač; i (3) priprema NPS na bazi sirovina iz bioobnovljivih izvora sa modifikovanim vlaknima nanoceluloze dodavanjem modifikovanih vlakana nanoceluloze u predpolimer, zatim dodavanjem aktivatora i inicijatora i na kraju izvođenjem reakcije umrežavanja na povišenoj temperaturi tokom 24 h. Dobijena NPS na bazi sirovina iz bioobnovljivih izvora je ekološki prihvatljivog sastava i ima poboljšana mehanička svojstva u odnosu na NPS bez vlakana nanoceluloze. Dimetil itakonat, koji može da se dobije iz bioobnovljih sirovina, primenom predložene metode istovremeno se koristi i za modifikaciju vlakana nanoceluloze i kao reaktivni rastvarač za pripremu NPS. Na ovaj način se postiže jednostavna modifikacija vlakana nanoceluoze koja se hemijski vezuju za NPS matricu i bolje disperguju u njoj, a samim tim se postižu i bolja mehanička svojstva NPS na bazi sirovina iz bioobnovljivih izvora.Broj prijave: P-2025/006