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Radiation Effects in Materials || Effects of Electron Irradiation Upon Absorptive and Fluorescent Properties of Some Doped Optical Fibers
摘要： A review of the recent studies of the effect of irradiating silica-based fibers doped with rare earths and metals by a beam of high-energy (β) electrons is presented. Of the review’s main scope are the attenuation spectra’ transformations occurring in optical fiber of such types under electron irradiation, allowing, from one side, to recover some general essence of the phenomena involved and, from the other side, to draw the features that would make such fibers useful for applications, for example, in dosimetry and space technologies. Among the fibers of the current review’s choice, exemplifying the effect of electron irradiation most brightly, are ytterbium (Yb) and cerium (Ce) (the rare earths’ representatives) and bismuth (Bi) (the post-transitional metals representative) doped fibers, where a diversity of the electron-irradiation-related effects is encouraged.
关键词： optical bleaching,photodarkening,cerium- and bismuth-doped silica fibers,electron irradiation,ytterbium-
更新于2025-09-16 10:30:52
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The use of surfactant-filled mesoporous silica as an immobilising medium for a fluorescence lifetime pH indicator, providing long-term calibration stability
摘要： Surfactant filled mesoporous silica is applied as a matrix for immobilizing the fluorescence lifetime pH-indicator acridine. We demonstrate that this type of encapsulation provides a stable and uniform chemical environment for the indicator and has good proton transport properties leading to rapid pH response times. Furthermore, the immobilising medium effectively prevents leaching of the indicator, facilitates high long-term stability and does not influence the pH sensing-range of the indicator.
关键词： acridine,surfactant-filled mesoporous silica,fluorescence lifetime pH indicator,proton transport properties,long-term calibration stability
更新于2025-09-16 10:30:52
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AuNP and ssDNA capped mesoporous silica nanoparticles for laser controlled drug release
摘要： In order to improve drug e?cacy, and reduce drug toxicity and side e?ects, a novel drug controlled release system was developed based on mesoporous silica nanoparticles (MSNs) with gold nanoparticles (AuNPs) acting as pore caps and short single-stranded DNA (ssDNA) oligomers as the linker. The synthesised composites were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray di?raction (XRD), thermogravimetric analysis (TGA), zeta potential measurement, transmission electron microscopy (TEM) and UV-vis spectroscopy. The anticancer drug doxorubicin (Dox) was applied as a model drug to investigate the 808 nm near infrared (NIR) laser-controlled drug release behavior at di?erent pH by ?uorescence measurements. The investigation results demonstrate that this nanocarrier could achieve drug controlled release by external near-infrared (NIR) laser stimulation, which is expected to be applied in cancer therapy.
关键词： doxorubicin,near-infrared laser,single-stranded DNA,mesoporous silica nanoparticles,drug controlled release,gold nanoparticles
更新于2025-09-16 10:30:52
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Bright emission and high photoluminescence CsPb <sub/>2</sub> Br <sub/>5</sub> NCs encapsulated in mesoporous silica with ultrahigh stability and excellent optical properties for white light-emitting diodes
摘要： All-inorganic cesium lead halide perovskite CsPb2Br5 nanocrystals (NCs) have attracted tremendous attention owing to their unique optoelectronic properties. However, their tolerance to atmospheric moisture is limited by their corresponding poor stability, which has drastically prevented the broad application of the materials in lasers, light-emitting diodes (LED) and, most recently, photocatalysis. To address this issue, we have successfully demonstrated the design and synthesis of a nanocomposite material, CsPb2Br5 NCs coated in mesoporous silica (NCs-MS), with high photoluminescence (PL) intensity, bright emission and enhanced water stability, thermal stability and photostability versus naked CsPb2Br5 NCs. The components and structure of the prepared CsPb2Br5 NCs-MS nanocomposite were investigated in detail by PL, XRD, TEM and HAADF-STEM studies. Furthermore, the mechanism behind the outstanding stability and optical properties of the prepared NCs-MS nanocomposite is discussed. Owing to the ultrahigh stability of the NCs-MS nanocomposite, the white LED (WLED) assembled by coating the CsPb2Br5 NCs-MS nanocomposite and commercial red CaAlSiN3:Eu2+ phosphor powder on an InGaN blue chip showed CIE chromaticity coordinates of (0.3377, 0.3309) and presented excellent optical parameters with a CRI of 82.9, a CCT of 5035 K and an LE of 64.9 lm W?1. This work provides a new pathway for the synthesis and application of all-inorganic cesium lead halide perovskite materials in WLEDs and display devices.
关键词： stability,white light-emitting diodes,mesoporous silica,photoluminescence,CsPb2Br5 NCs
更新于2025-09-16 10:30:52
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Radiation-Induced Absorption of Light in Undoped-Silica-Core Optical Fibers in the Near-Infrared Range: Effect of Drawing Conditions
摘要： Eight identical undoped-silica-core, fluorosilicate-cladding preforms have been drawn into optical fibers under different drawing regimes (temperature T, tension, and speed). Next, the fibers have been γ-irradiated, with radiation-induced absorption (RIA) of light measured at the wavelength λ = 1.55 μm and at the dose of 2.5 kGy (7.4–7.6 Gy/s). RIA is found to strongly increase with an increase in T, which proves to be the main drawing parameter determining the fiber radiation resistance. It is established that the RIA dependence on T?1 is exponential.
关键词： fiber drawing temperature,radiation-induced light absorption,undoped-silica-core optical fiber
更新于2025-09-16 10:30:52
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4-Mercaptobenzoic Acid Labeled Gold-Silver-Alloy-Embedded Silica Nanoparticles as an Internal Standard Containing Nanostructures for Sensitive Quantitative Thiram Detection
摘要： In this study, (4-mercaptobenzoic acid labeled SiO2@Au@4-MBA@Ag gold-silver-alloy-embedded silica nanoparticles) nanomaterials were investigated for the detection of thiram, a pesticide. First, the presence of Au@4-MBA@Ag alloys on the surface of SiO2 was confirmed by the broad bands of ultraviolet-visible spectra in the range of 320–800 nm. The effect of the 4-MBA (4-mercaptobenzoic acid) concentration on the Ag shell deposition and its intrinsic SERS (surface-enhanced Raman scattering) signal was also studied. Ag shells were well coated on SiO2@Au@4-MBA in the range of 1–1000 μM. The SERS intensity of thiram-incubated SiO2@Au@4-MBA@Ag achieved the highest value by incubation with 500 μL thiram for 30 min, and SERS was measured at 200 μg/mL SiO2@Au@4-MBA@Ag. Finally, the SERS intensity of thiram at 560 cm?1 increased proportionally with the increase in thiram concentration in the range of 240–2400 ppb, with a limit of detection (LOD) of 72 ppb.
关键词： gold–silver-alloy-embedded silica nanoparticles,internal standard,thiram,ultrasensitive detection
更新于2025-09-16 10:30:52
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A Study of the Optical Properties of a Multimode Silica Optical Fiber with a Reflective Shell from a Fluorinated Thermoplastic Polymer
摘要： The optical properties of a silica–polymer optical fiber with a light-guide core with a diameter of 430 μ m and a reflecting shell with a thickness of 70 μ m from a thermoplastic copolymer of tetrafluoroethylene with ethylene of Tefzel brand have been experimentally studied. The polymer coating is applied to a silica fiber directly in the fiber draw apparatus by the die method from a thermoplastic melt. The optical losses of the drawn fiber and the numerical aperture and its dependence on the fiber length are measured. It is established that a light propagating through the fiber is noticeably scattered by the reflecting shell, which is associated with the crystallinity of the polymer. The distribution of the scattered radiation intensity along the fiber axis and the indicatrix of radiation scattering by the shell are measured. The relative contributions of scattering and absorption of light in the shell to the total optical losses of the fiber are estimated. The possible use of optical fibers of this structure in laser medicine is considered.
关键词： silica–polymer optical fiber,laser medicine,scattering indicatrix
更新于2025-09-16 10:30:52
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Steady State X-Ray Radiation Induced Attenuation in Canonical Optical Fibers
摘要： So-called canonical optical fibers are samples especially designed to highlight the impact of some manufacturing process parameters on the radiation responses. Thanks to the results obtained on these samples, it is thus possible to define new procedures to better control the behaviors of optical fibers in radiation environments. In the present work, we characterized the responses, under steady state X-rays, of canonical samples representative of the most common fiber types differing by their core-dopants: pure silica, Ge, Al and P. Their radiation induced attenuation (RIA) spectra were measured online at both room temperature (RT) and liquid nitrogen temperature (LNT), in the energy range [~0.6 - ~3.0] eV (~2100 nm - ~410 nm), highlighting the RIA growth kinetics during the fiber exposure up to an accumulated dose of ~200 Gy(SiO2) at a constant dose rate of 100 mGy/s at RT. At LNT, the deposited doses varied between 100 and 180 Gy, with a time dependent dose rate. In order to understand the origin of the excess losses and the difference between the RIA spectral shapes observed at the two temperatures, a spectral decomposition of the optical losses has been performed using a set of Gaussian absorption bands related to the already known point defects. As a result, if the RIA in the visible domain is quite well understood, the knowledge on RIA origin in the near-IR remains incomplete, justifying new and deeper studies to clarify the fibers response under steady state irradiation.
关键词： point defects,radiation effects,attenuation,pure silica core and doped optical fibers,canonical samples
更新于2025-09-16 10:30:52
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High-efficient, spherical and thermal-stable carbon dots@silica fluorescent composite as rare earth-free phosphors for white LED
摘要： This paper reported a facile synthesis path to realize high-luminescent rare-earth-free composite powder, by embedding blue/green-emitting N-doped carbon dots into silica nano-spheres (CD@SiO2). Carbon dots were evenly dispersed in CD@SiO2 composites and eventually the aggregation-induced luminescence quenching is eliminated. Compared to the naked CDs, CD@SiO2 composites exhibit perfectly spherical morphology with average size of ~200 nm, signi?cantly enhanced emission intensity (> 4 times) and better thermal stability (T50 > 150 °C). As-synthesized CD@SiO2 own strong blue/green emission with high quantum e?ciency (QE) over 60%. White LEDs prototypes with promising properties, i.e. CRI = 89.1, CCT = 4850 K and CIE coordinates = (0.3514, 0.3715), were fabricated by combining blue/green CD@SiO2 and red CdTe@CaCO3 composites with NUV chip. All results indicate that these rare-earth-free, mono-dispersed spherical, and thermal-stable composite materials with e?cient blue/green emission could be an exceptional choice as phosphors for LED application.
关键词： Composite phosphors,Silica nano-sphere,Carbon dots,Luminescence,Light-emitting diodes
更新于2025-09-16 10:30:52
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Synthesis and application of a surface ionic imprinting polymer on silica-coated Mn-doped ZnS quantum dots as a chemosensor for the selective quantification of inorganic arsenic in fish
摘要： A novel room temperature phosphorescence chemosensor probe has been successfully developed and applied to the selective detection and quantification of inorganic arsenic (As(III) plus As(V)) in fish samples. The prepared material (IIP@ZnS:Mn QDs) was based on Mn-doped ZnS quantum dots coated with (3-aminopropyl) triethoxysilane and an As(III) ionic imprinted polymer. The novel use of vinyl imidazole as a complexing reagent when synthesizing the ionic imprinted polymer guarantees that both inorganic arsenic species (As(III) and As(V)) can interact with the recognition cavities in the ionic imprinted polymer. After characterization, several studies were performed to enhance the interaction between the targets (As(III) and As(V) ions) and the IIP@ZnS:Mn QDs nanoparticles. The optimization and validation process showed that the composite material offers high selectivity (high imprinting factor) for inorganic arsenic species. The limit of quantification for total inorganic As was 29.6 μg kg?1, value lower than the EU/EC regulation limits proposed for other foodstuffs than fish, such as rice. The proposed method is therefore simple, requires short analysis times and offers good sensitivity, precision (inter-day relative standard deviations lower than 10%), and quantitative analytical recoveries. The method has been successfully applied to assess total inorganic arsenic in several fishery products, showing good agreement with the total inorganic arsenic concentration (As(III) plus As(V)) found after applying other advanced and expensive methods such those based on high-performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry.
关键词： Ionic imprinted polymer,Silica-coated Mn-doped ZnS quantum dots,Fish,Room temperature phosphorescence,Chemosensor probe,Inorganic arsenic
更新于2025-09-16 10:30:52