3828 research outputs found
Sort by
The dynamics of phase transitions and symmetry changes with laser heating in ZnO(Co) nanoparticles
No full textIn this study, we investigated the effects of laser-induced heating on ZnO samples with varying CoO dopant
concentrations, prepared using the traditional calcination method at 600 ◦C. The relationship between peak
intensity, phase, and symmetry changes during laser heating and its relation to dopant concentration was
explored. Our results revealed phase transitions during the additional heating process, highlighting that such
transitions can occur even when symmetry remains unchanged. The key dopant concentrations at which phase
transitions are most evident were found to be 30 % CoO and 70 % CoO. This study provides insights into the
complex behavior of CoO doped ZnO under laser-induced heating and contributes to understanding phase
transition mechanisms in these materials
Modified Z-scheme heterojunction of TiO2/polypyrrole recyclable photocatalyst
No full textA straightforward physical mixing method was used to prepare the highly efficient TiO2/polypyrrole (PPy) photocatalysts of hydrothermally prepared TiO2 and PPy, obtained by the chemical oxidative polymerization, with different amounts of PPy (0, 0.5, 1, 1.5, 3, and 5 wt.%). Synthesized composites were characterized by XRPD, FTIR, FESEM, EDS, BET, and UV–Vis methods, while their photocatalytic activity was estimated towards the degradation of toxic dye Reactive Orange 16 (RO16) based on UV–Vis and TOC. XRPD showed that the TiO2 was obtained as nanoanatase with crystallites of 26 nm. Band gap energies of the nanocomposites decreased with the PPy content increase from 3.11(3) to 2.94(3) eV. The TiO2/1%PPy demonstrated the highest photocatalytic activity by completely degrading RO16 for 120 min under simulated solar light with degradation described by the pseudo-first reaction order with the rate constant of 0.056(5) min−1. It was established that 73% of the total reactive oxidative species were h+ and that the photodegradation mechanism followed a slightly modified direct Z-scheme in which PPy played an active and irreplaceable role by opening a new reaction path. Besides extremely high photocatalytic efficiency, the recyclability of TiO2/1%PPy was confirmed since no decrease in efficiency was found after several runs of photocatalysis
Artificial Intelligence for Cultural Heritage
No full textRecent technological advances have opened a growing spectrum of research focused on developing artificial intelligence (AI) tools tailored to the needs of cultural heritage preservation. AI is now actively applied for inpainting techniques for restoration of aged oil paintings and manuscripts, as well as for 3D reconstruction of archeological artifacts and historical sites, and enhancement of accessibility through virtual and augmented reality experiences. Deep-learning models also contribute to the attribution of authorship, stylistic analysis, and even the deciphering of ancient or damaged scripts. Additionally, AI-driven monitoring systems are being used to safeguard cultural heritage and detect risks from environmental threats such as natural disasters and conflicts in real time, using satellite imagery and real-time analytics. Despite the promising developments, challenges remain regarding ethical issues, standardization, cross-disciplinary coordination, and more. Initiatives such as AI4Culture and HeritageWatch.AI indicate a strategic shift toward embedding AI into cultural policy and practice. This abstract outlines the expanding role of AI as a structural component in the future of heritage restoration, conservation, research, and engagement
POLYCRYSTALLINE AND EPITAXIAL THIN FILMS OF La1-xNaxMnO3
No full textThe renewed interest on doped-manganites came from the observation of a high magnetoresistive effect, designed as “colossal” (CMR), which triggered the attention of the scientific community both for fundamental research and for applicative possibilities [1]. The research efforts during last 10 years have pointed out the role played in the manganites by the different oxidation states, 3+ and 4+, of the manganese ions [2]. The so-called double exchange transfer via oxygen anions, is responsible for the appearance of ferromagnetism, metallic conductivity, and colossal magnetoresistance.
Polycrystalline and epitaxial thin films of La1-xNaxMnO3 (x = 0; 0.05; 0.10; 0.15; 0.30) were prepared by spin coating technique on various substrates (Si, Si/Pt and SrTiO3 (100)) from acetate solution. XRD analysis showed a slight shift in the peaks` positions towards high 2θ, revealing the incorporation of Na ions (x ≤ 0.10) in the structure of LaMnO3. FE-SEM, AFM, and Raman spectroscopy analyzed the films’ structure. The structure and morphology of the films were examined and correlated with sheet resistance and magnetic properties, considering the type and thickness of the films
Silicon-solubilizing potential of bacteria isolated from the rhizosphere of field-grown wheat in Chernozem soil
No full textAlthough silicon (Si) is one of the most abundant mineral elements in agricultural soils, its availability
to crops is often limited. After the decomposition of crop residues, amorphous silica structures known
as phytoliths can persist in the soil for extended periods due to their low solubility, serving as a potential
source of bioavailable Si. To overcome nutrient deficiencies, particularly phosphorus (P), the
rhizosphere microbiota, along with crop root activity, plays a key role in enhancing soil nutrient
availability. To explore the Si-solubilizing potential of bacteria from the rhizosphere of field-grown
wheat cultivated in Chernozem soil (Vojvodina region, Serbia), a total of 350 bacterial strains were
isolated. An initial screening was performed to identify strains with the greatest capacity to solubilize
phytoliths, using their ability to mobilize P from poorly soluble calcium hydroxyapatite as a proxy.
Based on this, one strain with the highest P-solubilizing potential from each of the
putative Bacillus and Pseudomonas genera was selected for further analysis. These selected isolates
were subsequently tested in vitro for their ability to solubilize phytoliths previously extracted from
wheat plants grown in the same field. The results showed that bacterial strains from the wheat
rhizosphere can significantly mobilize Si from phytoliths, with the extent of mobilization depending on
the substrate pH. Our findings suggest that rhizosphere bacterial activity plays a role in mobilizing Si
from amorphous phytogenic Si pools. They also indicate that the targeted selection and application of
efficient bacterial strains, combined with proper rhizosphere management, could be a promising
strategy to enhance Si availability in agricultural soils
Classification and forecasting in students’ progress using Multiple-Criteria Decision Making, K-Nearest Neighbors, and Multilayer Perceptron methods
No full textThe research paper addresses students’ performance in higher education.
It proposes using the MCDM method - Promethee II to assess students’ knowledge
and the K-Nearest Neighbors (KNN) and Multilayer Perceptron (MLP) methods for
grade classification. The main goals are tracking and diagnosing students’ knowledge
levels, predicting their outcomes, and providing tailored recommendations.
It helps to identify students at risk of not passing the course and evaluates teaching
methods. This encourages student engagement and progress during the course.
The research demonstrates the suitability of Promethee II, MLP, and KNN methods
for effectively monitoring, classifying, and predicting students’ progress during the
semester, enhancing the objectivity of the assessment process
Comparative lipopeptide analysis of Bacillus velezensis strains with antagonistic activity
No full textMembers of the genus Bacillus are widely recognized as microbial factories, capable of producing diverse biologically active compounds with strong inhibitory effects against plant pathogens. Among antimicrobial compounds, cyclic lipopeptides of the surfactin, iturin, and fengycin families have gained significant recognition for their potential applications in biotechnology. This study aimed to analyze lipopeptide profile of four Bacillus velezensis strains (P-FC 55, RD-FC 88, R-FC 102, and R-FC 114) with proven in vitro and in vivo antagonistic activity against plant pathogenic bacterium Xanthomonas campestris pv. campestris on cabbage cv. Futoški in order to identify key metabolites potentially responsible for their antimicrobial effect. Ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC Q-ToF MS) was used to analyze lipopeptides present in ethyl acetate extracts of B. velezensis. UHPLC Q-ToF MS revealed the presence of different isoforms of surfactin (C12–C17) in all four strains, while differences between strains were only observed in terms of the abundance of detected metabolites. Molecular screening of strains for the presence of genes encoding lipopeptides with known antimicrobial properties (bacillomycin D, iturin operon, fengycin, surfactin, and kurstakin synthetase) highlighted the genetic potential of all strains to produce surfactins, bacillomycin D, and iturins (except R-FC 114) under certain growing conditions. Identification of strains as B. velezensis was confirmed after sequencing of their amplified DNA with the same primers. The obtained results indicate the potential role of lipopeptides, especially surfactins, in antimicrobial potential of four tested B. velezensis strains isolated from Serbian autochthonous cabbage cv. Futoški
Bacillus velezensis: a natural shield against black rot disease on Serbian autochthonous cabbage cv. Futoški
No full textSerbian autochthonous cabbage cv. Futoški is highly susceptible to the plant pathogenic bacterium Xanthomonas
campestris pv. campestris, the causal agent of black rot, leading to significant economic losses. This study aimed to isolate
indigenous Bacillus spp. and Pseudomonas spp. strains with beneficial traits for biocontrol of black rot. From a total
of 115 potential antagonistic strains, four (coded as P-FC 55, RD-FC 88, R-FC 102, And R-FC 114) identified as species
Bacillus velezensis were selected as candidates based on strong in vitro antagonistic activity, both as whole cultures
and cell-free supernatants, against the most virulent X. campestris pv. campestris strain (XcFC 231) identified in this
study. No statistically significant differences were observed between the efficacy of whole cultures and supernatants
of biocontrol candidates. Preventive inoculation approaches (seed and foliar) of biocontrol candidates consistently
outperformed curative treatments across all strains, highlighting their potential as preferred application strategies. The
most effective B. velezensis strain was RD-FC 88, applied in the form of a whole culture during preventive foliar application,
achieving 93.86% disease suppression, surpassing copper oxychloride (89.26%) under the same conditions.
Chemical profiling (GC/MS and UHPLC–QToF MS) of ethyl acetate extracts revealed the presence of a wide range
of antimicrobial organic compounds (e.g., 2,3-butanediol, urea, succinic acid, thymine, phenylalanine, 9H-purin-6-ol)
and lipopeptides (surfactins C12–
C17), which may be contributing factors to the biocontrol activity of the strains. Next
to the surfactins, molecular screening for the presence of genes encoding the production of lipopeptides with antimicrobial
activity indicated the potential of strains to produce bacillomycin D and iturins (except R-FC 114) under certain
growing conditions. Preventive application (seed and foliar) of biocontrol candidate strains led to an increase
in epidermal flavonoid and chlorophyll content, while the opposite trend was observed in curative treatments. The
results of this study highlight the strong potential of the B. velezensis strains P-FC 55, RD-FC 88, R-FC 102, And R-FC
114 for controlling black rot disease on the cabbage cv. Futoški, with possible broader applicability to other cabbage
cultivars and Brassicaceae crops
Zn-Co co-doped spinel ferrite and strontium hexaferrite nanocomposites obtained by “one-pot” green sol-gel synthesis: A study of the ferroelectric, magnetic and electrical properties
No full textThe one-pot green sol-gel synthesis procedure using mandarin peel extract as the reducing agent and nitrate metal precursors with calcination at 950 ◦C was applied to obtain Zn-Co spinel ferrite (magnetically soft) and strontium hexaferrite (magnetically hard) nanocomposites with spinel ferrite/hexaferrite content ratios of 50:50 (SH55), 60:40 (SH64) and 70:30 (SH73). Analysis of the measured X-ray diffraction patterns showed magnetoplumbite (M-type) strontium hexaferrite with zinc and cobalt incorporated into this phase forming SrCo0.2Zn0.2Fe11.6O18.8 with a c/a lattice ratio of ~3.92 and cubic spinel zinc-cobalt ferrite phase with lattice parameter a ~8.42 Å. The crystallite size of the hexaferrite phase decreased as the content of spinel ferrite phase increased. Specifically, the hexaferrite phase platelets were 46 nm wide and 27 nm thick for SH55, and 36 nm wide and 22 nm thick for SH73. Meanwhile, the spinel ferrite phase had a consistent crystallite size of 24–25 nm. X-ray photoelectron spectroscopy confirmed successful incorporation of Fe, Sr, Zn, Co, and O into the produced nanocomposites. Room-temperature ferromagnetic hysteresis loops showed a spring coupling behavior with coercivity decreasing from 115.8 (SH55) to 41.9 Oe (SH73) and saturation magnetization increasing from 18.2
(SH55) to 38.2 emu/g (SH73) with the increase in the spinel phase content. Room-temperature ferroelectric loops recorded at a frequency of 100 Hz and showed maximal polarization of 147.6–161.3 nC/cm2 and remanent polarization from 40.2 to 35.8 nC/cm2. The Arrhenius dependence of the DC conductivity on temperature was in line with the Mott model for phonon-assisted hopping of small polarons. The conductivity changed with frequency in accordance with the Jonscher’s power law. The correlated barrier model described the conduction mechanism, while the Kohlrausch, Williams and Watts function explained the transition from long-range to
short-range hopping and non-Debye relaxation mechanism for the analyzed spinel ferrite/hexaferrite nanocomposites
Comparative Analysis of Lettuce Morphological and Physiological Traits: Effects of Cultivar, Biofertiliser, and Seasonal Variations in Different Soil Types
No full textA multi-factor analysis of cultivar, biofertiliser, and growing season was conducted to optimise lettuce agronomic and quality traits in diverse soil conditions. The goal was to identify soil differences and offer practical recommendations to improve lettuce traits and quality for farmers and the processing industry. The study employed a complete block design with four treatments, three involving biofertilisers, applied to six lettuce cultivars grown in two contrasting soil types- Mollic Gleysol (Calcaric)-GL and Hortic Anthrosol (Terric, Transportic)-AT, across three consecutive greenhouse seasons (autumn, winter, and spring). Biofertilisers were applied to the soil before transplanting and foliarly during the growing cycle, with four of the following treatments: control (no fertilisation), a fertiliser containing beneficial microorganisms, a Trichoderma-based fertiliser, and a combination of both. In GL soil, all biofertiliser treatments increased rosette height, leaf number, and stem length, whereas in AT soil, all morphological parameters declined significantly. The green cultivars ‘Aquino’ and ‘Kiribati’ showed superior morphological performance, particularly in spring and winter. Rosette fresh weight, a key indicator of plant biomass, reached 236.4 g in ‘Aquino’ grown in GL soil, and 208.6 g in ‘Kiribati’ grown in AT soil. Dualex™ leaf sensor measurement indicated that ‘Aquino’ exhibited the highest nitrogen balance index (NBI), while the red cultivar ‘Gaugin’ recorded the highest chlorophyll, flavonoid, and anthocyanin contents. Combined fertilisers increased NBI by 6.3% and chlorophyll by 6.8% in GL soil. Trichoderma fertiliser alone raised NBI by 6.8% in GL soil, whereas in AT soil, plants accumulated more flavonoids and anthocyanins (by 9.2% and 8.5%). Optical parameters were highest in autumn. The three-factor experiment demonstrated that cultivar, biofertiliser, and growing season significantly influenced the majority of measured traits. Correlation analysis revealed that rosette fresh weight was positively associated with NBI but negatively correlated with quality-related traits. Based on these findings, cultivars ‘Aquino’, ‘Kiribati’, and ‘Gaugin’ are recommended for both farmers and the processing industry to improve lettuce production quantity and quality. Overall, cultivar, biofertiliser, and season strongly influenced the measured parameters, underscoring the importance of tailoring biofertiliser application to soil type and season to achieve optimal production outcomes