Search Results (95)

In this study, Lu_2.5Y_0.5(Al_2.5Ga_2.5)O₁₂ (LuYAGG) single-crystal scintillators doped with terbium ions (Tb³⁺) at concentrations of 0.5, 1, 5, and 10 mol% were successfully synthesized using the floating zone method. The structural, optical, photoluminescence (PL), and scintillation properties of the Tb³⁺-doped crystals were systematically investigated with a focus on their potential for high-performance scintillator applications. X-ray diffraction (XRD) confirmed the formation of a pure garnet phase without any secondary phases, indicating the successful incorporation of Tb³⁺ into the LuYAGG lattice. Optical transmittance spectra revealed high transparency in the visible range. Photoluminescence measurements showed characteristic Tb³⁺ emission peaks, with the strongest green emission observed from the ⁵D₄ → ⁷F₅ transition, particularly for the 5 mol% sample. The PL decay curves further confirmed that this concentration offers a favorable balance between radiative efficiency and minimal non-radiative losses. Under γ-ray excitation, the 5 mol% Tb³⁺-doped crystal exhibited the highest light yield, surpassing the performance of other concentrations and even outperforming Bi₄Ge₃O₁₂ (BGO) in relative comparison, with an estimated yield of approximately 60,000 photons/MeV. Scintillation decay time analysis revealed that the 5 mol% sample also possessed the fastest decay component, indicating its superior capability for radiation detection. Although 10 mol% Tb³⁺ still showed good performance, slight quenching effects were observed, while lower concentrations (0.5 and 1 mol%) suffered from longer decay and lower emission efficiency due to limited activator density. These findings clearly identify with 5 mol% Tb³⁺ as the optimal dopant level in LuYAGG single crystals, offering a synergistic combination of high light yield and excellent optical transparency. This work highlights the strong potential of LuYAGG:Tb³⁺ as a promising candidate for the next-generation scintillator materials used in medical imaging, security scanning, and high-energy physics applications. Full article

The persistent operational instability of all-inorganic cesium lead halide (CsPbX₃) perovskite nanocrystals (NCs) has hindered their integration into white-light-emitting diodes (WLEDs). This study introduces a transformative approach by engineering a phase transition from CsPbBr₃ NCs to zirconium bromide (ZrBr₄)-stabilized hexagonal nanocomposites (HNs) through a modified hot-injection synthesis. Structural analyses revealed that the ZrBr₄-mediated phase transformation induced a structurally ordered lattice with minimized defects, significantly enhancing charge carrier confinement and radiative recombination efficiency. The resulting HNs achieved an exceptional photoluminescence quantum yield (PLQY) of 92%, prolonged emission lifetimes, and suppressed nonradiative decay, attributed to effective surface passivation. The WLEDs with HNs enabled a breakthrough luminous efficiency of 158 lm/W and a record color rendering index (CRI) of 98, outperforming conventional CsPbX₃-based devices. The WLEDs exhibited robust thermal stability, retaining over 80% of initial emission intensity at 100 °C, and demonstrated exceptional operational stability with negligible PL degradation during 50 h of continuous operation at 100 mA. Commission Internationale de l’Éclairage (CIE) coordinates of (0.35, 0.32) validated pure white-light emission with high chromatic fidelity. This work establishes ZrBr₄-mediated HNs as a paradigm-shifting material platform, addressing critical stability and efficiency challenges in perovskite optoelectronics and paving the way for next-generation, high-performance lighting solutions. Full article

Purpose—The reconstruction of worn-out urban fabrics poses a significant challenge in sustainable urban development, as such places, due to their decay and infrastructural inefficiencies, diminish residents’ quality of life and generate many environmental, social, and economic issues. Meanwhile, green building techniques have emerged as a novel option because they focus on environmental sustainability and resource efficiency. Nonetheless, effectively executing these strategies in worn-out urban fabrics necessitates a thorough feasibility evaluation to identify the associated obstacles and implementation prerequisites. The current study aimed to identify critical indicators for the feasibility of employing contemporary green building techniques in the repair of worn-out urban fabrics in Iran. The revitalization of worn-out urban fabrics is essential to enhancing the quality of life of urban inhabitants. Regarding this matter, the concept of green buildings, which emphasizes environmental sustainability, deserves significant attention. Meanwhile, feasibility assessments can help to successfully implement these changes in worn-out urban fabrics. Accordingly, the current study seeks to determine the essential indicators for the feasibility assessment of using initiative green building methods in the revitalization of worn-out urban fabric. Design/methodology/approach—In this vein, two rounds of the Delphi survey technique were carried out to identify and consolidate the indicators for the feasibility assessment of using initiative green building methods in the revitalization of the worn-out urban fabric in Iran. A research questionnaire was developed after reviewing the literature. It consists of four main dimensions (i.e., environmental, cultural–social, management–legal, and technical–technological) containing a total of 26 distinct indicators. The questionnaire was distributed among 123 experienced specialists. Eventually, the collected data were analyzed using the SPSS and Smart PLS programs. Findings—The results revealed that identified dimensions and indicators can be considered significant and essential indices in evaluating the use of initiative green building methods in the revitalization of worn-out urban fabric. Furthermore, the sequence of importance of the dimensions was environmental, followed by technical and technological, cultural and social, and managerial and legal. The environment, with an average rating of 3.33, ranked first; technical–technology, with an average rating of 2.45, ranked second; cultural–social, with an average rating of 2.15, ranked third; and management–legal, with an average rating of 2.07, ranked fourth. Furthermore, among the ranked indicators, the utilization of natural plants as a source of inspiration for living design in communal areas, aimed at toxin absorption and gas mitigation while achieving thermal equilibrium, received the highest average rating of 18.22, securing the first position. Conversely, the indicator assessing residents’ financial capacity, and the establishment of executive assurances and governmental support for the revitalization of the neighborhoods’ fabric garnered the lowest average rating of 10.98, placing it 26th and final. Originality/value—This research’s findings can significantly influence public policy and urban planning initiatives, aiding in the sustainable repair of worn-out urban fabrics in Iran by offering a systematic framework for evaluating the viability of innovative green building techniques. Full article

Guava fruit is susceptible to decay, leading to losses in storability and quality. ε-Poly-l-lysine (ε-PL) is a safe antimicrobial polypeptide that has proven to be effective in preserving produce’s quality. In the present research, ε-PL, at multiple concentrations (1, 2 and 4 g/L), was adopted to treat guavas, and the fruit were stored at 25 °C for 15 d. The results indicated that ε-PL retarded the guava storability decline and enhanced its quality. Treated guavas had a better appearance, as well as the lower disease index, relative electrolytic leakage, weight loss, respiration intensity, a* and b* values and reducing sugar content. They also showed higher firmness, commercially acceptable fruit rate, titratable acidity, L* value, total soluble sugar, vitamin C and sucrose levels. The optimal concentration of ε-PL was determined to be 2 g/L. Furthermore, compared to control guavas, fruit treated with 2 g/L ε-PL exhibited lower levels of superoxide anion, hydrogen peroxide and malondialdehyde but higher antioxidant enzyme activities in terms of ascorbate peroxidase, peroxidase, catalase and superoxide dismutase. These findings suggested that ε-PL raised the antioxidant enzyme activities to enhance the fruit’s antioxidant ability. This, in turn, reduced the reactive oxygen species levels and lipid peroxidation, ultimately improving the guava’s quality. Consequently, ε-PL is of practical significance for commercial application as it suppresses decay and stabilizes the quality of guavas, enhancing their postharvest marketability. Full article

Ce-doped Lu₂Si₂O₇ has a high density, high luminescence efficiency even at high temperatures, and a high effective atomic number, making it a promising candidate for use as a radiation detector in medical devices and resource exploration equipment. In this study, we grow and characterize Pr³⁺ and Ce³⁺-doped Lu₂Si₂O₇ single crystals by systematically varying the Ce³⁺ to Pr³⁺ ratio to further improve scintillation properties. The optical characterization results show a bidirectional energy transfer: from the Pr³⁺ 5d levels to the Ce³⁺ 5d levels and from the Ce³⁺ 5d levels to the Pr³⁺ 4f levels. Consistently with this result, the PL decay time of emission from the Pr³⁺ 5d–4f transition tends to become faster as the Ce³⁺/Pr³⁺ ratio increases, due to the energy transfer from the Pr³⁺ 5d levels to the Ce³⁺ 5d levels. Additionally, (Ce_0.0022 Pr_0.0016 Lu_0.9962)₂Si₂O₇ exhibits a high light yield comparable to Ce-doped Lu₂Si₂O₇ and a slightly faster decay time than Ce-doped Lu₂Si₂O₇. Full article

The self-activated halotungstate Ba₃WO₅Cl₂ was successfully synthesized using a high-temperature solid-state method. X-ray diffraction analysis (XRD) confirmed the formation of a single-phase compound with a monoclinic crystal structure, ensuring the material’s purity and structural integrity. The luminescence properties of Ba₃WO₅Cl₂ were thoroughly investigated using both optical and laser-excitation spectroscopy. The photoluminescent excitation (PLE) and emission (PL) spectra, together with the corresponding decay curves, were recorded across a broad temperature range, from 10 K to 480 K. The charge transfer band (CTB) of the [WO₅Cl] octahedron was clearly identified in both the PL and the PLE spectra under ultraviolet light excitation, indicating efficient energy transfer within the material’s structure. A strong blue emission could be detected around 450 nm, which is characteristic of the material’s luminescent properties. However, this emission exhibited thermal quenching as the temperature increased, a common phenomenon where the luminescence intensity diminishes due to thermal effects. To better understand the thermal quenching behavior, variations in luminescence intensity and decay time were analyzed using a straightforward thermal quenching model. This comprehensive study of Ba₃WO₅Cl₂ luminescent properties not only deepens the understanding of its photophysical behavior but also contributes to the development of novel materials with tailored optical properties for specific technological applications. Full article

We elaborate a method for determining the 0D–1D nanostructure size by photoluminescence (PL) emission spectrum dependence on the nanostructure dimensions. As observed, the high number of diamond-like carbon nanocones shows a strongly blue-shifted PL spectrum compared to the bulk material, allowing for the calculation of their top dimensions of 2.0 nm. For the second structure model, we used a sharp atomic force microscope (AFM) tip, which showed green emission localized on its top, as determined by confocal microscopy. Using the PL spectrum, the calculation allowed us to determine the tip size of 1.5 nm, which correlated well with the SEM measurements. The time-resolved PL measurements shed light on the recombination process, providing stretched-exponent decay with a τ₀ = 1 ns lifetime, indicating a gradual decrease in exciton lifetime along the height of the cone from the base to the top due to surface and radiative recombination. Therefore, the proposed method provides a simple optical procedure for determining an AFM tip or other nanocone structure sharpness without the need for sample preparation and special expensive equipment. Full article

The global demand for blueberries has increased due to their health benefits, but postharvest losses, particularly firmness loss and decay, present significant challenges. This study evaluated the effects of high CO₂ concentrations (15% and 20%) applied for 3 d at 1.0 °C on highbush (cv. ‘Duke’) and rabbiteye (cv. ‘Ochlockonee’) blueberries, with a focus on quality maintenance during cold storage. The quality parameters evaluated included titratable acidity, pH, total soluble solids, weight loss, and decay. The effect of gaseous treatments on firmness was analyzed using mechanical parameters and the expression of genes related to cell wall integrity (XTH23, PL8, PG, PM3, EXP4, and VcGH5). Treatment efficacy varied between species. High CO₂ levels reduced decay in both cultivars, but only the highbush cultivar (‘Duke’) showed improvements in firmness. In ‘Duke’, CO₂ treatments affected the expression of XTH23, PL8, and GH5, while the role of PG and PME in maintaining firmness was minimal, with no significant differences between treatments. In ‘Ochlockonee’, CO₂ effectively reduced weight loss but did not improve firmness. In conclusion, these results highlight the need for tailored postharvest strategies for different blueberry cultivars and suggest that short-term high CO₂ treatments may effectively prolong the postharvest life of highbush blueberries. Full article

AlGaN is attractive for fabricating deep ultraviolet (DUV) optoelectronic and electronic devices of light-emitting diodes (LEDs), photodetectors, high-electron-mobility field-effect transistors (HEMTs), etc. We investigated the quality and optical properties of Al_xGa_1−xN films with high Al fractions (60–87%) grown on sapphire substrates, including AlN nucleation and buffer layers, by metal–organic chemical vapor deposition (MOCVD). They were initially investigated by high-resolution X-ray diffraction (HR-XRD) and Raman scattering (RS). A set of formulas was deduced to precisely determine x(Al) from HR-XRD data. Screw dislocation densities in AlGaN and AlN layers were deduced. DUV (266 nm) excitation RS clearly exhibits AlGaN Raman features far superior to visible RS. The simulation on the AlGaN longitudinal optical (LO) phonon modes determined the carrier concentrations in the AlGaN layers. The spatial correlation model (SCM) analyses on E₂(high) modes examined the AlGaN and AlN layer properties. These high-x(Al) Al_xGa_1−xN films possess large energy gaps E_g in the range of 5.0–5.6 eV and are excited by a DUV 213 nm (5.8 eV) laser for room temperature (RT) photoluminescence (PL) and temperature-dependent photoluminescence (TDPL) studies. The obtained RTPL bands were deconvoluted with two Gaussian bands, indicating cross-bandgap emission, phonon replicas, and variation with x(Al). TDPL spectra at 20–300 K of Al_0.87Ga_0.13N exhibit the T-dependences of the band-edge luminescence near 5.6 eV and the phonon replicas. According to the Arrhenius fitting diagram of the TDPL spectra, the activation energy (19.6 meV) associated with the luminescence process is acquired. In addition, the combined PL and time-resolved photoluminescence (TRPL) spectroscopic system with DUV 213 nm pulse excitation was applied to measure a typical AlGaN multiple-quantum well (MQW). The RT TRPL decay spectra were obtained at four wavelengths and fitted by two exponentials with fast and slow decay times of ~0.2 ns and 1–2 ns, respectively. Comprehensive studies on these Al-rich AlGaN epi-films and a typical AlGaN MQW are achieved with unique and significant results, which are useful to researchers in the field. Full article

Diaporthe longicolla (syn. Phomopsis longicolla) is an important seed-borne fungal pathogen and the primary cause of Phomopsis seed decay (PSD) in soybean. PSD is one of the most devastating seed diseases, reducing soybean seed quality and yield worldwide. As part of a genome sequencing project on the fungal Diaporthe–Phomopsis complex, draft genomes of eight D. longicolla isolates were sequenced and assembled. Sequences of mitochondrial genomes were extracted and analyzed. The circular mitochondrial genomes ranged from 52,534 bp to 58,280 bp long, with a mean GC content of 34%. A total of 14 core protein-coding genes, 23 tRNA, and 2 rRNA genes were identified. Introns were detected in the genes of atp6, cob, cox1, cox2, cox3, nad1, nad2, nad5, and rnl. Three isolates (PL7, PL10, and PL185E) had more introns than other isolates. Approximately 6.4% of the mitochondrial genomes consist of repetitive elements. Moreover, 48 single-nucleotide polymorphisms (SNPs) and were identified. The mitochondrial genome sequences of D. longicolla will be useful to further study the molecular basis of seed-borne pathogens causing seed diseases, investigate genetic variation among isolates, and develop improved control strategies for Phomopsis seed decay of soybean. Full article

Pleurotheciaceae is a genera-rich and highly diverse family of fungi with a worldwide distribution in aquatic and terrestrial habitats. During the investigation of lignicolous freshwater fungi from karst landscapes in Yunnan Province, China, 15 fresh strains were obtained from submerged decaying wood. Based on the morphology and phylogenetic analysis of a combined LSU, ITS, SSU, and rpb2 sequence dataset, Obliquifusoideum triseptatum, Phaeoisaria obovata, Pleurotheciella brachyspora, Pl. longidenticulata, and Pl. obliqua were introduced as new species, P. synnematica and Rhexoacrodictys melanospora were reported as new habitat records, and P. sedimenticola and Pl. hyalospora were reported as new collections. In addition, based on morphological comparisons and phylogenetic analysis, we accepted Obliquifusoideum into in the family Pleurotheciaceae (Pleurotheciales, Savoryellomycetidae). Freshwater habitats are the primary habitats of Pleurotheciaceae species, and Yunnan Province has the highest concentration and species diversity of Pleurotheciaceae in China. Full article

Gadolinium pyrosilicate (GPS, Gd₂Si₂O₇) single crystals with different doping concentrations of Tb (0.1–2.0 mol%) are successfully fabricated using the floating-zone technique. In this work, the dependence of Tb-doping concentration on the photoluminescence (PL) and scintillation properties of Tb-doped GPS (Tb:GPS) has been investigated. The PL emission contour graph shows multiple emissions, with the strongest emissions at 378 nm for 0.1% and 0.5% Tb-doping and 544 nm for 1.0% and 2.0% Tb-doping, corresponding to Tb³⁺ 4f-4f transitions. The PL lifetimes of the specimens range from 4.89 to 5.22 ms. The scintillation spectra exhibit comparable wavelength and intensity trends to the PL emission. The scintillation lifetimes of the specimens range from 2.41 to 3.88 ms. The Tb:GPS specimens demonstrate a relatively excessive afterglow level, with Af₂₀ values ranging from 1640 to 7250 ppm and Af₄₀ values ranging from 136 to 362 ppm. Using recently developed pulse height measurement for millisecond decay scintillators, under excitation at 662 keV γ-rays, the 1.0% Tb:GPS specimen exhibits the highest scintillation light yield among all other specimens at 95,600 ph/MeV, making Tb:GPS one of the highest light yield oxide scintillators. Full article

Recycled soda-lime glass powder is a sustainable material that is also often considered a filler in cement-based composites. The changes in the surface properties of the glass particles due to the treatments were analyzed by X-ray photoelectron spectroscopy (XPS) and optical spectroscopy. We have found that there is a relatively high level of carbon contamination on the surface of the glass particles (around 30 at.%), so plasma technology and thermal annealing were tested for surface cleaning. Room temperature plasma treatment was not sufficient to remove the carbon contamination from the surface of the recycled glass particles. Instead, the room temperature plasma treatment of recycled soda-lime glass particles leads to a significant enhancement in their room temperature photoluminescence (PL) by increasing the intensity and accelerating the decay of the photoluminescence. The enhanced blue PL after room-temperature plasma treatment was attributed to the presence of carbon contamination on the glass surface and associated charge surface and interfacial defects and interfacial states. Therefore, we propose blue photoluminescence under UV LED as a fast and inexpensive method to indicate carbon contamination on the surface of glass particles. Full article

This study aims to enhance the optical and thermal properties of cesium-based perovskite nanocrystals (NCs) through surface passivation with organic sulfonate (or sulfonic acid) ligands. Four different phenylated ligands, including sodium β-styrenesulfonate (SbSS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (SPTS), and 4-dodecylbenzenesulfonic acid (DBSA), were employed to modify blue-emitting CsPbBr_1.5Cl_1.5 perovskite NCs, resulting in improved size uniformity and surface functionalization. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the successful anchoring of sulfonate or sulfonic acid ligands on the surface of perovskite NCs. Moreover, the photoluminescence quantum yield increased from 32% of the original perovskite NCs to 63% of the SPTS-modified ones due to effective surface passivation. Time-resolved photoluminescence decay measurements revealed extended PL lifetimes for ligand-modified NCs, indicative of reduced nonradiative recombination. Thermal stability studies demonstrated that the SPTS-modified NCs retained nearly 80% of the initial PL intensity when heated at 60 °C for 10 min, surpassing the performance of the original NCs. These findings emphasize the optical and thermal stability enhancement of cesium-based perovskite NCs through surface passivation with suitable sulfonate ligands. Full article

Freshly harvested Tremella fuciformis contains high water content with an unprotected outer surface and exhibits high respiration rates, which renders it prone to moisture and nutrient loss, leading to decay during storage. Our research utilized ε-poly-L-lysine (ε-PL) and chitosan as a composite coating preservative on fresh T. fuciformis. The findings revealed that the ε-PL + chitosan composite coating preservative effectively delayed the development of diseases and reduced weight loss during storage compared to the control group. Furthermore, this treatment significantly decreased the respiration rate of T. fuciformis and the activity of respiratory metabolism-related enzymes, such as alternative oxidase (AOX), cytochrome c oxidase (CCO), succinic dehydrogenase (SDH), 6-phosphogluconate dehydrogenase, and glucose-6-phosphate dehydrogenase (6-PGDH and G-6-PDH). Additionally, the composite coating preservative also delayed the depletion of ATP and ADP and maintained higher levels of the energy charge while preserving low levels of AMP. It also sustained heightened activities of Mg²⁺-ATPase, Ca²⁺-ATPase, and H⁺-ATPase enzymes. These results demonstrate that utilizing the ε-PL + chitosan composite coating preservative can serve as a sufficiently safe and efficient method for prolonging the shelf life of post-harvest fresh T. fuciformis. Full article