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Temperature-dependent luminescence of europium-doped Ga₂O₃ ceramics
No full textThis study explores the synthesis and luminescent properties of europium-doped gallium oxide (Ga₂O₃:Eu) ceramics fabricated via electron beam-assisted synthesis (EBAS) at 1.4 MeV. The resulting Ga₂O₃:Eu ceramics exhibit a nanocrystalline structure with an average crystallite size of ∼30 nm, high crystallinity, and minimal lattice strain (<0.5 %). Luminescence analysis from 4 K to 300 K reveals both intrinsic and europium-induced emissions. While intrinsic Ga₂O₃ emission exhibits thermal quenching above 100 K, Eu³⁺-related emissions, notably the 611 nm red emission, show thermal stability, retaining ∼90 % of their intensity at 300 K. Additionally, a novel low-temperature emission peak at 1.74 eV, potentially associated with electron beam-induced defects, was detected, meriting further exploration. These findings indicate that Ga₂O₃:Eu ceramics synthesized via EBAS hold promise for optoelectronic, radiation detection, and high-temperature applications, given their rapid production and enhanced thermal stability
Dental composite materials based on Zn/Al-layered double hydroxide and their physical mechanical properties
No full textDental materials' demands can be answered using composite materials, as composite properties are suitable for tailoring the material's behavior. Poly (methyl methacrylate) (PMMA) is usually a material of choice in dental applications, and its mechanical properties can be improved in terms of modulus, strength, and hardness. The chosen reinforcement in this publication was Zn/Al-layered double hydroxide (LDH), as this material has functional property modification possibilities. The reinforcement was synthesized using the coprecipitation process on a laboratory scale. The dispersion of the reinforcement was done with ultrasonication, and the composites prepared contained 1, 3, and 5 wt% of reinforcement, and the so-prepared composites were compared to the matrix. Improvements were observed in terms of the elastic modulus and tensile strength, and the best performance was observed in the composite with 3 wt% of particles. Hardness increased with the addition of particles and the higher the particle content, the better the hardness. Materials were tested using dynamic mechanical techniques, and it was proven that the addition of particles lowers the Tg of the composite compared to the pure matrix. The addition of particles diminished the affinity of the material for polar liquids such as water
Correlation of microRNAs-10b/21/34a expression levels with IDH1-mutation status in patients with glioblastoma
No full textIsocitrate dehydrogenase mutations play a significant role in gliomagenesis. Specific microRNAs such as miR-10b/21 act as oncogenic microRNAs, while miR-34a acts as tumor suppressors in glioblastoma. Our study aimed to investigate the mutation status of IDH correlate with microRNAs-10b/21/34a expression levels in patients with glioblastoma. Methods. The study included 43 patients diagnosed with glioblastoma. We examined microRNA-10b, microRNA-21 and microRNA-34a expression levels in peripheral blood mononuclear cells after surgery and prior to concurrent radiotherapy with temozolomide, at the 15th and 30th fractions of radiotherapy with temozolomide. The data on IDH1 mutation status were gathered from medical history and histopathology. Results. Two groups were created to assess the association of microRNAs-10b/21/34a expression levels: glio-blastoma IDH1-wild type and glioblastoma IDH1-mutant + Not Other Specified (NOS). The median microRNA-10b expression level before the initiation of concurrent radiotherapy with temozolomide was 130.44 (52.20 - 622.53) in the IDH1-wildtype glioblastoma group and 94.61 (2.13 - 816.89) in the IDH1-mutant + glioblastoma NOS group. The median microRNA-21 expression level was 57.16 (2.68 - 278.98) in the IDH1-wildtype glioblastoma group and 69.74 (4.60 - 825.43) in the IDH1-mutant + glioblastoma NOS group. The median microRNA-34a expression level was 13.52 (3.16 - 105.20) in the IDH1-wildtype glioblastoma group and 10.11 (1.00 - 210.55) in the IDH1-mutant + glioblastoma NOS group. The results showed no statistically significant difference in the expression levels of miR-10b/21/34a between the two groups (p > 0.05). Conclusion. Our results suggest that the IDH1 mutation status may not be a critical factor for altered expression of microRNAs-10b/21/34a in glioblastoma patients
From RTA to conventional annealing: Impact on optical losses and metallic character of TiN films
No full textThis study investigates the effects of rapid thermal annealing (RTA) and conventional annealing on the optical and metallic properties of TiN thin films. TiN films were subjected to Au ion implantation, followed by RTA and conventional annealing at 400°C and 500°C for 1 h. Ion implantation led to a decrease in metallicity and optical losses compared to the as-deposited film, with plasma frequency increasing from 6.44 eV to 8.85 eV and Drude broadening from 0.82 eV to 2.43 eV. After RTA, both plasma frequency and Drude broadening were lowered to 4.95 eV and 0.73 eV, respectively, enhancing the metallic character and further minimizing optical losses. Conventional annealing at 400 °C and 500 °C also decreased metallicity but resulted in comparable losses to RTA. However, losses slightly increased at 500 °C due to the growth of Au nanoparticles, which introduced additional scattering mechanisms. These findings demonstrate the importance of thermal treatments in tuning TiN films’ optical and electronic properties, with RTA offering similar results to conventional annealing but with shorter processing times, making it ideal for applications requiring low optical losses and metallic characteristics. © 2025 Elsevier B.V
Long-term analysis of the semiconductor HPGe detector system through internal quality control program-A Thirteen years Follow-up
No full textQuality control of a laboratory process has become a reliable tool for monitoring and obtaining results that provide evidence of the stability of a measuring system. Gamma spectrometry is no exception. Moreover, establishing an internal quality control program ensures valid results regarding the long-term stability of the semiconductor measuring system. In this paper, we present the results of internal quality control performed on the HPGe detector over the period from 2010 to 2022. During this time, net peak area, Full Width at Half Maximum (FWHMs), Full Width at Tenth Maximum (FWTMs), and FWTM/FWHM ratio, as well as the total number of counts in the background were monitored and analysed. For this purpose, two point sources (60Co and 137Cs) were used. The obtained results demonstrate that adhering to good laboratory practice and implementing a properly established internal quality control program enables the identification of irregularities in the operation of the detector system and facilitates timely corrections, thereby ensuring the reliability of the HPGe detector system. © 2025 Elsevier Lt
Impact of Melatonin Application in Winemaking on Phenolic Content, Tryptophan Metabolites, and Bioactivity of Red Wine
No full textGlobal wine consumption drives the interest for high-quality wine with enhanced health benefits. Yeast-produced tryptophan metabolites, including melatonin, a potent antioxidant, emerged as promising agents for enhancing functional properties of food and beverages. This study represents the pioneering work addressing whether melatonin supplementation during vinification affects Moldova red wine quality. Total phenolic/flavonoid contents, DPPH, and FRAP assays were measured via spectrophotometry, anthocyanins, and tryptophan metabolites using UPLC-MS/MS and UPLC-FLD, as well as cytotoxicity with the MTT assay. Results showed that addition of melatonin during the winemaking process increased total phenolic/flavonoid content, as well as the antioxidant capacity evidenced by increased anti-DPPH radical activity. These effects might be due to the stimulation of phenolic compound biosynthesis, particularly anthocyanins malvidin-3-O-glucoside, peonidin-3-O-glucoside, and delphinidin 3-O-glucoside, which were found to be increased in the treated wine. Additionally, the study revealed that melatonin-enriched wine exhibited increased cytotoxicity against two cancer cell lines, HCT116 and PANC-1. Finally, melatonin supplementation enhanced the concentration of kynurenic acid, which, due to its cytoprotective and antioxidant properties, could further increase the health benefits of the resulting wine. These findings offer promising avenue for future research of melatonin-driven functional properties of wine and provide step forward to a natural product with added value
Estabilidad e impacto neurotóxico de pesticidas organofosforados en ambientes acuosos
No full textIntroduction/purpose: Organophosphates are widely used nowadays. They have applications as pesticides, drugs, plasticizers, flame retardants, or chemical warfare agents. Their acute toxicity is ascribed to inhibiting acetylcholinesterase (AChE), a key enzyme in the transmission of nerve impulses in animals. Their toxic effects manifest by acetylcholine accumulation in the nerve synapses and can lead to paralysis or death. Organo-thiophosphate pesticides (OPs) are used in large quantities. Their oxo-analogs can also be found in the environment due to oxidation. Once accumulated in the environment, they exhibit toxic effects on non-target organisms. Methods: The hydrolysis of OPs in different pH was systematically analyzed, and their neurotoxic effects were evaluated. The concentration of the investigated pesticides during decomposition was monitored by ultra-performance liquid chromatography (UPLC). At the same time, a decrease in the toxicity of the treated samples was observed by measuring the activity of the enzyme AChE. Results: OPs decompose rapidly in alkaline aqueous solutions but are highly stable in acidic solutions. Chlorpyrifos hydrolyzes the fastest and dimethoate the slowest. The toxicity of these OP solutions decreases over time, indicating that more toxic products were not formed. Conclusion: The presented results can provide a sound basis for further efforts to find simple and efficient decomposition methods of OPs. © 2025 The Authors
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. © 2025 The American Ceramic Society
Exploring the luminescence mechanism and enabling tunable emission in Sr3YGa2O7.5: Bi3+, Eu3+ phosphors for advanced UV-converted white LEDs
No full textInorganic phosphors with tunable broadband emission hold significant applications in solid-state lighting. Herein, a series of novel Sr3YGa2O7.5: Bi3+, Eu3+ (abbreviated as SYGO: Bi3+, Eu3+) phosphors with tunable optical properties were synthesized by high-temperature solid-state reaction process. The photoluminescence excitation (PLE) spectrum of Sr3YGa2O7.5: Bi3+ ranges from 200 to 400 nm with two peaks at 280 and 331 nm, matching well with the n-UV chip based white light-emitting diodes (WLED). Under ultraviolet light excitation, a single Bi3+-doped Sr3YGa2O7.5 phosphor exhibited five distinct luminescence peaks at 410, 510, 560, 605, and 700 nm at 10 K, which are attributed to the 3P1→1S0 transition emissions of Bi3+ ions occupying the four Sr sites and one Y site within the Sr3YGa2O7.5 host lattice. The optical tuning of the Sr3YGa2O7.5: Bi3+ phosphor is achieved by designing the Bi3+→Eu3+ energy transfer and changing the excitation wavelength based on the selected site occupation. The Commission Internationale de l'Eclairage (CIE) coordinates and emission color of the Sr3YGa2O7.5: Bi3+, Eu3+ phosphors were successfully tuned from blue via white to red. The energy transfer efficiency from Bi3+ to Eu3+ can reach as high as 89.54 %, and this energy transfer process is predominantly governed by the dipole-quadrupole interaction. In addition, the white LED device prepared by combination of SYGO: 0.02Bi3+, 0.03Eu3+ phosphors with 365 nm chip has high color rendering index (CRI) of 85.5 and low correlated color temperature of 3537 K. As the driving current increases, the white light emitting diodes (WLED) device demonstrates good color stability. Based on these findings, the synthesized SYGO: Bi3+, Eu3+ phosphors can serve as color-tunable and single-phase white phosphors with potential applications in UV-excited white LEDs. © 202