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Search Results (298)

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Keywords = absorption decay

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17 pages, 3146 KiB  
Article
Ultraviolet Upconversion Emission of CaAl2SiO6 Polycrystals Doped with Pr3+ Ions
by Karol Lemański, Nadiia Rebrova, Patrycja Zdeb-Stańczykowska and Przemysław Jacek Dereń
Molecules 2025, 30(14), 2944; https://doi.org/10.3390/molecules30142944 - 11 Jul 2025
Viewed by 263
Abstract
The spectroscopic properties of Pr3+ ions in the aluminosilicate matrix were investigated for the first time. Synthesis of CaAl2SiO6 (CASO) polycrystals doped with Pr3+ ions was carried out using the sol–gel method. The crystalline structures have been confirmed [...] Read more.
The spectroscopic properties of Pr3+ ions in the aluminosilicate matrix were investigated for the first time. Synthesis of CaAl2SiO6 (CASO) polycrystals doped with Pr3+ ions was carried out using the sol–gel method. The crystalline structures have been confirmed with XRD measurement. The absorption, excitation, emission spectra, and time decay profiles of the praseodymium (III) ions were measured and analyzed. It was found that upon excitation with visible light, this material exhibits emission mainly in the UVC region, via an upconversion emission process. The Stokes emission in the visible range is observed mainly from the 3P0 and 1D2 energy levels. The 1D23H4 emission is very stable even at very high temperatures. The studied aluminosilicate phosphors possess characteristics that confirm their potential in upconversion emission applications. Full article
(This article belongs to the Section Physical Chemistry)
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16 pages, 4224 KiB  
Article
Optimizing Museum Acoustics: How Absorption Magnitude and Surface Location of Finishing Materials Influence Acoustic Performance
by Milena Jonas Bem and Jonas Braasch
Acoustics 2025, 7(3), 43; https://doi.org/10.3390/acoustics7030043 - 11 Jul 2025
Viewed by 307
Abstract
The architecture of contemporary museums often emphasizes visual aesthetics, such as large volumes, open-plan layouts, and highly reflective finishes, resulting in acoustic challenges, such as excessive reverberation, poor speech intelligibility, elevated background noise, and reduced privacy. This study quantified the impact of surface—specific [...] Read more.
The architecture of contemporary museums often emphasizes visual aesthetics, such as large volumes, open-plan layouts, and highly reflective finishes, resulting in acoustic challenges, such as excessive reverberation, poor speech intelligibility, elevated background noise, and reduced privacy. This study quantified the impact of surface—specific absorption treatments on acoustic metrics across eight gallery spaces. Room impulse responses calibrated virtual models, which simulated nine absorption scenarios (low, medium, and high on ceilings, floors, and walls) and evaluated reverberation time (T20), speech transmission index (STI), clarity (C50), distraction distance (rD), Spatial Decay Rate of Speech (D2,S), and Speech Level at 4 m (Lp,A,S,4m). The results indicate that going from concrete to a wooden floor yields the most rapid T20 reductions (up to −1.75 s), ceiling treatments deliver the greatest STI and C50 gains (e.g., STI increases of +0.16), and high-absorption walls maximize privacy metrics (D2,S and Lp,A,S,4m). A linear regression model further predicted the STI from T20, total absorption (Sabins), and room volume, with an 84.9% conditional R2, enabling ±0.03 accuracy without specialized testing. These findings provide empirically derived, surface-specific “first-move” guidelines for architects and acousticians, underscoring the necessity of integrating acoustics early in museum design to balance auditory and visual objectives and enhance the visitor experience. Full article
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24 pages, 7707 KiB  
Article
Improving Building Acoustics with Coir Fiber Composites: Towards Sustainable Construction Systems
by Luis Bravo-Moncayo, Virginia Puyana-Romero, Miguel Chávez and Giuseppe Ciaburro
Sustainability 2025, 17(14), 6306; https://doi.org/10.3390/su17146306 - 9 Jul 2025
Viewed by 441
Abstract
Studies underscore the significance of coir fibers as a sustainable building material. Based on these insights, this research aims to evaluate coir fiber composite panels of various thicknesses as eco-friendly sound absorbing alternatives to synthetic construction materials like rockwool and fiberglass, aligning its [...] Read more.
Studies underscore the significance of coir fibers as a sustainable building material. Based on these insights, this research aims to evaluate coir fiber composite panels of various thicknesses as eco-friendly sound absorbing alternatives to synthetic construction materials like rockwool and fiberglass, aligning its use with the United Nations Sustainable Development Goals. Acoustic absorption was quantified with an impedance tube, and subsequent simulations compared the performance of coir composite panels with that of conventional materials, which constitutes an underexplored evaluation. Using 10 receiver points, the simulations reproduced the acoustic conditions of a multipurpose auditorium before and after the coir covering of parts of the rear and posterior walls. The results indicate that when coir coverings account for approximately 10% of the auditorium surface, reverberation times at 250, 500, 2000, and 4000 Hz are reduced by roughly 1 s. Furthermore, the outcomes reveal that early reflections occur more rapidly in the coir-enhanced model, while the values of the early decay time parameter decrease across all receiver points. Although the original configuration had poor speech clarity, the modified model achieved optimal values at all the measurement locations. These findings underscore the potential of coir fiber panels in enhancing acoustic performance while fostering sustainable construction practices. Full article
(This article belongs to the Special Issue Sustainable Architecture: Energy Efficiency in Buildings)
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15 pages, 3748 KiB  
Article
Constructing 1 + 1 > 2 Photosensitizers Based on NIR Cyanine–Iridium(III) Complexes for Enhanced Photodynamic Cancer Therapy
by Ziwei Wang, Weijin Wang, Qi Wu and Dongxia Zhu
Molecules 2025, 30(12), 2662; https://doi.org/10.3390/molecules30122662 - 19 Jun 2025
Viewed by 453
Abstract
Photosensitizers with high singlet oxygen (1O2) generation capacity under near-infrared (NIR) irradiation are essential and challenging for photodynamic therapy (PDT). A simple yet effective molecular design strategy is realized to construct 1 + 1 > 2 photosensitizers with synergistic [...] Read more.
Photosensitizers with high singlet oxygen (1O2) generation capacity under near-infrared (NIR) irradiation are essential and challenging for photodynamic therapy (PDT). A simple yet effective molecular design strategy is realized to construct 1 + 1 > 2 photosensitizers with synergistic effects by covalently integrating iridium complexes with cyanine via ether linkages, as well as introducing aldehyde groups to suppress non-radiative decay, named CHO−Ir−Cy. It is demonstrated that CHO−Ir−Cy successfully maintains the NIR absorption and emission originated from cyanine units and high 1O2 generation efficiency from the iridium complex part, which gives full play to their respective advantages while compensating for shortcomings. Density functional theory (DFT) calculations reveal that CHO−Ir−Cy exhibits a stronger spin–orbit coupling constant (ξ (S1, T1) = 9.176 cm−1) and a reduced energy gap (ΔE = −1.97 eV) between triplet excited states (T1) and first singlet excited states (S1) compared to parent Ir−Cy or Cy alone, directly correlating with its enhanced 1O2 production. Remarkably, CHO−Ir−Cy demonstrates superior cellular internalization in 4T1 murine breast cancer cells, generating substantially elevated 1O2 yields compared to individual Ir−Cy/Cy under 808 nm laser irradiation. Such enhanced reactive oxygen species production translates into effective cancer cell ablation while maintaining favorable biocompatibility, significant phototoxicity and negligible dark toxicity. This molecular engineering strategy overcomes the inherent NIR absorption limitation of traditional iridium complexes and ensures their own high 1O2 generation ability through dye–metal synergy, establishing a paradigm for designing metal–organic photosensitizers with tailored photophysical properties for precision oncology. Full article
(This article belongs to the Special Issue Advances in Coordination Chemistry, 3rd Edition)
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15 pages, 2389 KiB  
Article
Tracking Photoinduced Charge Redistribution in a Cu(I) Diimine Donor–Bridge–Acceptor System with Time-Resolved Infrared Spectroscopy
by Sean A. Roget, Wade C. Henke, Maxwell Taub, Pyosang Kim, Jonathan T. Yarranton, Xiaosong Li, Karen L. Mulfort and Lin X. Chen
Photochem 2025, 5(2), 16; https://doi.org/10.3390/photochem5020016 - 19 Jun 2025
Viewed by 406
Abstract
Understanding electron density migration along excited-state pathways in photochemical systems is critical for optimizing solar energy conversion processes. In this study, we investigate photoinduced electron transfer (PET) in a covalently linked donor–bridge–acceptor (D-B-A) system, where [Cu(I)-bis(1,10-phenanthroline)]+ acts as an electron donor, and [...] Read more.
Understanding electron density migration along excited-state pathways in photochemical systems is critical for optimizing solar energy conversion processes. In this study, we investigate photoinduced electron transfer (PET) in a covalently linked donor–bridge–acceptor (D-B-A) system, where [Cu(I)-bis(1,10-phenanthroline)]+ acts as an electron donor, and anthraquinone, tethered to one of the phenanthroline ligands via a vibrationally active ethyne bridge, behaves as an electron acceptor. Visible transient absorption spectroscopy revealed the dynamic processes occurring in the excited state, including PET to the acceptor species. This was indicated by the spectral features of the anthraquinone radical anion that appeared on a timescale of 30 ps in polar solvents. Time-resolved infrared (TRIR) spectroscopy of the alkyne vibration (CC stretch) of the ethyne bridge provided insight into electronic structural changes in the metal-to-ligand charge transfer (MLCT) state and along the PET reaction coordinate. The observed spectral shift and enhanced transition dipole moment of the CC stretch demonstrated that there was already partial delocalization to the anthraquinone acceptor following MLCT excitation, verified by DFT calculations. An additional excited-state TRIR signal unrelated to the vibrational mode highlighted delocalization between the phenanthroline ligands in the MLCT state. This signal decayed and the CC stretch narrowed and shifted towards the ground-state frequency following PET, indicating a degree of localization onto the acceptor species. This study experimentally elucidates charge redistribution during PET in a Cu(I) diimine D-B-A system, yielding important information on the ligand design for optimizing PET reactions. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry, 3rd Edition)
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12 pages, 4893 KiB  
Article
Wideband Near-Infrared Hot-Electron Photodetector Based on Metal Grating Structure
by Hao Huang, Fei Liu, Zidong Chen, Bowen Zhang and Ailing Zhang
Photonics 2025, 12(5), 518; https://doi.org/10.3390/photonics12050518 - 21 May 2025
Viewed by 365
Abstract
The generation of hot electrons through non-radiative decay processes of surface plasmons (SPs) has been extensively demonstrated, enabling the preparation of high-performance hot-electron photodetectors without limitations imposed by material band gap widths. In this paper, a near-infrared wideband hot-electron metal semiconductor photodetector (WHEMSPD) [...] Read more.
The generation of hot electrons through non-radiative decay processes of surface plasmons (SPs) has been extensively demonstrated, enabling the preparation of high-performance hot-electron photodetectors without limitations imposed by material band gap widths. In this paper, a near-infrared wideband hot-electron metal semiconductor photodetector (WHEMSPD) is proposed based on a metal grating plasmonic structure, and its optical and electrical properties are numerically verified. This structure exhibits excellent broadband characteristics within the long-wave near-infrared range (LW-NIR) of 1200–1800 nm, achieving an absorption of approximately 0.7 between 1200 and 1700 nm, with a peak of 0.98 at 1400 nm. The metal grating structure can effectively enhance the excitation of plasmons on the surface and thus increase the absorption within a larger bandwidth. In terms of electrical performance, the responsivity of the WHEMSPD reaches over 20 mA/W within the wavelength range of 1200–1500 nm, with the peak responsivity reaching 28.3 mA/W around 1320 nm. WHEMSPDs in the LW-NIR can be widely used in military, remote sensing, communication, and other related fields. Full article
(This article belongs to the Special Issue Thermal Radiation and Micro-/Nanophotonics)
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15 pages, 3619 KiB  
Article
Effects of Stumping on Ecological Stoichiometry and Allometric Growth in Leaf, Absorptive Root, and Rhizosphere Soil of Hippophae rhamnoides
by Lu Liu, Yuefeng Guo, Wangsuo Liu, Darifu Ba and Fei Feng
Plants 2025, 14(10), 1513; https://doi.org/10.3390/plants14101513 - 19 May 2025
Viewed by 360
Abstract
To clarify the effects of stumping on the C, N, and P allocation strategy of Hippophae rhamnoides L. artificial forests at the decaying stage in feldspathic sandstone areas, we tested stumping heights of 0, 10, 15, and 20 cm from the ground (denoted [...] Read more.
To clarify the effects of stumping on the C, N, and P allocation strategy of Hippophae rhamnoides L. artificial forests at the decaying stage in feldspathic sandstone areas, we tested stumping heights of 0, 10, 15, and 20 cm from the ground (denoted H1, H2, H3, and H4, respectively) with non-stumped trees as a control (CK). The N (LN, RN), P (LP, RP), and N:P (LN:LP, RN:RP) in the leaves and absorptive roots and the C, N, C:N, C:P, and N:P in rhizosphere soils after different treatments all manifested in the order H3 > H2 > H1 > H4 > CK. Among them, the LN and RN of H3 presented the largest amplitudes of increase (31% and 263%, respectively) compared with those of CK. There were very significant allometric relationships between LC and RC (−0.57, trade-off relationship), between LN and RN, and between LP and RP (0.32, 2.01; synergistic relationship) in stumped H. rhamnoides, and the accumulation rates of LC and LN were slower than those of RC and RN. After the stumping, certain correlations were present between the characteristics, except that neither LC nor RC significantly differed across the different treatments. The growth of H. rhamnoides after the different treatments was mainly regulated by P. The stumped H. rhamnoides grew at a faster rate, and the optimal stumping height was 15 cm. These findings are valuable for revegetation and for the prevention and control of soil erosion in feldspathic sandstone areas. Full article
(This article belongs to the Section Plant Ecology)
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8 pages, 3821 KiB  
Communication
Ultraviolet Background Radiation from Not-So-Dark Matter in the Galactic Halo
by Richard Conn Henry, Jayant Murthy and James Overduin
Universe 2025, 11(5), 148; https://doi.org/10.3390/universe11050148 - 3 May 2025
Viewed by 368
Abstract
Murthy et al. (2025) (hereafter Paper I) have recently reported the discovery of unexpectedly bright diffuse extreme-ultraviolet radiation at high latitudes in both the Northern and Southern Galactic Hemispheres. After correction for extinction by the total interstellar dust in the direction of each [...] Read more.
Murthy et al. (2025) (hereafter Paper I) have recently reported the discovery of unexpectedly bright diffuse extreme-ultraviolet radiation at high latitudes in both the Northern and Southern Galactic Hemispheres. After correction for extinction by the total interstellar dust in the direction of each observation, the spectra are nearly identical, suggesting that the radiation has a unique source and likely originates in the halo of our galaxy. The observed spectrum extends down to 912 Å, the interstellar hydrogen absorption edge. Radiation even slightly short of that edge would, if ubiquitous, be sufficient to explain the high degree of ionization in our galaxy and throughout the universe. We hypothesize that this newly discovered radiation originates in the slow decay of dark matter. The intensity of the radiation implies that the decay cannot be via the weak interaction, suggesting the existence of a new, even weaker fundamental interaction, consistent with the exceedingly long decay lifetime required. Full article
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17 pages, 14218 KiB  
Article
Structural Investigation and Energy Transfer of Eu3+/Mn4+ Co-Doped Mg3Ga2SnO8 Phosphors for Multifunctional Applications
by Zaifa Yang
Molecules 2025, 30(9), 1945; https://doi.org/10.3390/molecules30091945 - 27 Apr 2025
Viewed by 448
Abstract
In recent years, rare earth ion and transition metal ion co-doped fluorescent materials have attracted a lot of attention in the fields of WLEDs and optical temperature sensing. In this study, I successfully prepared the dual-emission Mg3Ga2SnO8:Eu [...] Read more.
In recent years, rare earth ion and transition metal ion co-doped fluorescent materials have attracted a lot of attention in the fields of WLEDs and optical temperature sensing. In this study, I successfully prepared the dual-emission Mg3Ga2SnO8:Eu3+,Mn4+ red phosphors and the XRD patterns and refinement results show that the prepared phosphors belong to the Fd-3m space group. The energy transfer process between Eu3+ and Mn4+ was systematically investigated by emission spectra and decay curves of Mg3Ga2SnO8:0.12Eu3+,yMn4+ (0.002 ≤ y ≤ 0.012) phosphors and the maximum value of transfer efficiency can reach 71.2%. Due to the weak thermal quenching effect of Eu3+, its emission provides a stable reference for the rapid thermal quenching of the Mn4+ emission peak, thereby achieving good temperature measurement performance. The relative thermometric sensitivities of the fluorescence intensity ratio and fluorescence lifetime methods reached a maximum value of 2.53% K−1 at 448 K and a maximum value of 3.38% K−1 at 473 K. In addition, the prepared WLEDs utilizing Mg3Ga2SnO8:0.12Eu3+ phosphor have a high color rendering index of 82.5 and correlated color temperature of 6170 K. The electroluminescence spectrum of the synthesized red LED device by Mg3Ga2SnO8:0.009Mn4+ phosphor highly overlaps with the absorption range of the phytochrome PFR and thus can effectively promote plant growth. Therefore, the Mg3Ga2SnO8:Eu3+,Mn4+ phosphors have good application prospects in WLEDs, temperature sensing, and plant growth illumination. Full article
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16 pages, 3466 KiB  
Article
High-Performance Self-Powered Photodetector Enabled by Te-Doped GeH Nanostructures Engineering
by Junting Zhang, Jiexin Chen, Shuojia Zheng, Da Zhang, Shaojuan Luo and Huixia Luo
Sensors 2025, 25(8), 2530; https://doi.org/10.3390/s25082530 - 17 Apr 2025
Viewed by 515
Abstract
Two-dimensional (2D) Xenes, including graphene where X represents C, Si, Ge, and Te, represent a groundbreaking class of materials renowned for their extraordinary electrical transport properties, robust photoresponse, and Quantum Spin Hall effects. With the growing interest in 2D materials, research on germanene-based [...] Read more.
Two-dimensional (2D) Xenes, including graphene where X represents C, Si, Ge, and Te, represent a groundbreaking class of materials renowned for their extraordinary electrical transport properties, robust photoresponse, and Quantum Spin Hall effects. With the growing interest in 2D materials, research on germanene-based systems remains relatively underexplored despite their potential for tailored optoelectronic functionalities. Herein, we demonstrate a facile and rapid chemical synthesis of tellurium-doped germanene hydride (Te-GeH) nanostructures (NSs), achieving precise atomic-scale control. The 2D Te-GeH NSs exhibit a broadband optical absorption spanning ultraviolet (UV) to visible light (VIS), which is a critical feature for multifunctional photodetection. Leveraging this property, we engineer photoelectrochemical (PEC) photodetectors via a simple drop-casting technique. The devices deliver excellent performance, including a high responsivity of 708.5 µA/W, ultrafast response speeds (92 ms rise, 526 ms decay), and a wide operational bandwidth. Remarkably, the detectors operate efficiently at zero-bias voltage, outperforming most existing 2D-material-based PEC systems, and function as self-powered broadband photodetectors. This work not only advances the understanding of germanene derivatives but also unlocks their potential for next-generation optoelectronics, such as energy-efficient sensors and adaptive optical networks. Full article
(This article belongs to the Special Issue Recent Advances in Photoelectrochemical Sensors)
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22 pages, 697 KiB  
Article
Determining Essential Indicators for Feasibility Assessment of Using Initiative Green Building Methods in Revitalization of Worn-Out Urban Fabrics
by Negar Ramezani, Jolanta Tamošaitienė, Hadi Sarvari and Mahboobeh Golestanizadeh
Sustainability 2025, 17(8), 3389; https://doi.org/10.3390/su17083389 - 10 Apr 2025
Viewed by 709
Abstract
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 [...] Read more.
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
(This article belongs to the Section Sustainable Engineering and Science)
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17 pages, 3949 KiB  
Article
Enhanced Long-Term In-Sensing Memory in ZnO Nanoparticle-Based Optoelectronic Synaptic Devices Through Thermal Treatment
by Dabin Jeon, Seung Hun Lee and Sung-Nam Lee
Materials 2025, 18(6), 1321; https://doi.org/10.3390/ma18061321 - 17 Mar 2025
Cited by 2 | Viewed by 651
Abstract
Two-terminal optoelectronic synaptic devices based on ZnO nanoparticles (NPs) were fabricated to investigate the effects of thermal annealing control (200 °C–500 °C) in nitrogen and oxygen atmospheres on surface morphology, optical response, and synaptic functionality. Atomic force microscopy (AFM) analysis revealed improved grain [...] Read more.
Two-terminal optoelectronic synaptic devices based on ZnO nanoparticles (NPs) were fabricated to investigate the effects of thermal annealing control (200 °C–500 °C) in nitrogen and oxygen atmospheres on surface morphology, optical response, and synaptic functionality. Atomic force microscopy (AFM) analysis revealed improved grain growth and reduced surface roughness. At the same time, UV–visible spectroscopy and photoluminescence confirmed a blue shift in the absorption edge and enhanced near-band-edge emission, particularly in nitrogen-annealed devices due to increased oxygen vacancies. X-ray photoelectron spectroscopy (XPS) analysis of the O 1s spectra confirmed that oxygen vacancies were more pronounced in nitrogen-annealed devices than in oxygen-annealed ones at 500 °C. Optical resistive switching was observed, where 365 nm ultraviolet (UV) irradiation induced a transition from a high-resistance state (HRS) to a low-resistance state (LRS), attributed to electron–hole pair generation and oxygen desorption. The electrical reset process, achieved by applying −1.0 V to −5.0 V, restored the initial HRS, demonstrating stable switching behavior. Nitrogen-annealed devices with higher oxygen vacancies exhibited superior synaptic performance, including higher excitatory postsynaptic currents, stronger paired-pulse facilitation, and extended persistent photoconductivity (PPC) duration, enabling long-term memory retention. By systematically varying UV exposure time, intensity, pulse number, and frequency, ZnO NPs-based devices demonstrated the transition from short-term to long-term memory, mimicking biological synaptic behavior. Learning and forgetting simulations showed faster learning and slower decay in nitrogen-annealed devices, emphasizing their potential for next-generation neuromorphic computing and energy-efficient artificial synapses. Full article
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16 pages, 6407 KiB  
Article
Enhancing Pinus pinaster Wood Durability Through Citric Acid Impregnation
by Luísa Cruz-Lopes, Mariana Sell, Rogério Lopes and Bruno Esteves
Sustainability 2025, 17(5), 1979; https://doi.org/10.3390/su17051979 - 25 Feb 2025
Cited by 1 | Viewed by 733
Abstract
Citric acid (CA), a naturally occurring compound in fruits, mainly citrus, has gained attention for its eco-friendly potential in wood modification. Through esterification, citric acid reacts with wood polymers to form bonds that improve adhesion, dimensional stability, and durability while reducing moisture absorption [...] Read more.
Citric acid (CA), a naturally occurring compound in fruits, mainly citrus, has gained attention for its eco-friendly potential in wood modification. Through esterification, citric acid reacts with wood polymers to form bonds that improve adhesion, dimensional stability, and durability while reducing moisture absorption and susceptibility to decay. This study evaluated the efficacy of CA as an eco-friendly wood treatment. Wood samples were treated with solutions at varying concentrations (5%, 10%, and 15%) and assessed for dimensional stability, mechanical properties, biological resistance, and ecotoxicity. CA treatments significantly improved dimensional stability, with higher concentrations yielding greater weight percent gain (WPG) and anti-swelling efficiency (ASE). Biological tests demonstrated exceptional termite resistance, with no survival and minimal mass loss in treated samples at higher concentrations. Similarly, fungal resistance improved, as citric acid inhibited fungal growth. Ecotoxicity tests showed relatively low phytotoxicity, with some decrease in germination indices (GI) at higher CA concentrations. These findings highlight CA as a sustainable wood treatment for enhanced durability and biodegradation resistance in construction and outdoor applications. Full article
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13 pages, 4412 KiB  
Article
Acoustic Emission During Rubber-like Deformation in Ni51Fe18Ga27Co4 Single Crystalline Shape Memory Alloys
by Lajos Daróczi, Sarah M. Kamel, László Z. Tóth, Elena Yu. Panchenko, Yuri I. Chumljakov and Dezső L. Beke
Metals 2025, 15(2), 131; https://doi.org/10.3390/met15020131 - 28 Jan 2025
Viewed by 747
Abstract
Acoustic emission, AE, belonging to a rubber-like deformation in a martensitic state after the stabilization aging of the stress-induced martensite (SIM aging) of Ni51Fe18Ga27Co4 single crystals in compression, were investigated. AE activity in the plateau regions [...] Read more.
Acoustic emission, AE, belonging to a rubber-like deformation in a martensitic state after the stabilization aging of the stress-induced martensite (SIM aging) of Ni51Fe18Ga27Co4 single crystals in compression, were investigated. AE activity in the plateau regions of the stress–strain loop is due to a massive reorientation from the variants produced by SIM aging to the variants preferred by the compressive stress (perpendicular to the stress used in SIM aging) and vice versa. For unloading, the large AE activity just at the knee point of the stress–stain curve is attributed to the difficulty of the re-nucleation of the SIM aging-stabilized martensite variant. The amplitude, peak energy, and area of signals can be described by power-like distributions and the characteristic exponents are in good agreement with data obtained in other alloys. Power law cross-correlations between the energy, E, and amplitude, A, as well as between the area, S, and the amplitude, A, were also analyzed. It was found that the exponents are given by 3φ as well as 2φ, respectively, with φ0.7. Normalized universal temporal shapes of avalanches (i.e., the UA  versus tA1φ plots, where U is the detected voltage) for a fixed area scale very well together. The tail of the normalized temporal shape decays more slowly than the theoretical prediction, which can be attributed to an intrinsic absorption of AE signals and/or to the overlap of sub-avalanches. Full article
(This article belongs to the Special Issue Metallic Functional Materials: Development and Applications)
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14 pages, 3200 KiB  
Article
Iodinated Copper–Cysteamine Nanoparticles as Radiosensitizers for Tumor Radiotherapy
by Miaomiao Zhang, Yu Yang, Ying Xu, Jie Wang and Shihong Li
Pharmaceutics 2025, 17(2), 149; https://doi.org/10.3390/pharmaceutics17020149 - 22 Jan 2025
Cited by 2 | Viewed by 1304
Abstract
Background/Objectives: Radiotherapy is a widely applied first-line clinical treatment modality of cancer. Copper–cysteamine (Cu-Cy) nanoparticles represent a new type of photosensitizer that demonstrates significant anti-tumor potential by X-ray-induced photodynamic therapy. Iodide is a high-Z element with superior X-ray absorption ability and has the [...] Read more.
Background/Objectives: Radiotherapy is a widely applied first-line clinical treatment modality of cancer. Copper–cysteamine (Cu-Cy) nanoparticles represent a new type of photosensitizer that demonstrates significant anti-tumor potential by X-ray-induced photodynamic therapy. Iodide is a high-Z element with superior X-ray absorption ability and has the β-decay radiotherapeutic nuclide, 131I, which emits Cherenkov light. In this study we aimed to investigate the X-ray-induced photodynamic therapy potential of iodinated Cu-Cy (Cu-Cy-I) nanoparticles and also explore the local treatment efficacy of 131I-labeled Cu-Cy-I ([131I]Cu-Cy-I) nanoparticles. Methods: The synthesis of [131I]Cu-Cy-I nanoparticles was performed with [131I]I anions. The in vitro radiobiological effects on tumor cells incubated with Cu-Cy-I nanoparticles by X-ray irradiation were investigated. The in vivo tumor growth-inhibitory effects of the combination of Cu-Cy-I nanoparticles with X-ray radiotherapy and [131I]Cu-Cy-I nanoparticles were evaluated with 4T1 tumor-xenografted mice. Results: The in vitro experiment results indicated that the X-ray irradiation with the presence of Cu-Cy-I nanoparticles produced a higher intracellular reactive oxygen species (ROS) level and more DNA damage of 4T1 cells and showed a stronger tumor cell killing ability compared to X-ray irradiation alone. The in vivo experimental results with 4T1 breast carcinoma-bearing mice showed that the combination of an intratumoral injection of Cu-Cy-I nanoparticles and X-ray radiotherapy enhanced the tumor growth-inhibitory effect and prolonged the mice’s lives. Conclusions: Cu-Cy-I nanoparticles have good potential as new radiosensitizers to enhance the efficacy of external X-ray radiotherapy. However, the efficacy of local treatment with [131I]Cu-Cy-I nanoparticles at a low 131I dose was not verified. The effective synthesis of smaller sizes of nanoparticles is necessary for further investigation of the radiotherapy potential of [131I]Cu-Cy-I nanoparticles. Full article
(This article belongs to the Section Nanomedicine and Nanotechnology)
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