LUMINESCENCE OF YAG:Ce DOPED WITH SILVER NANOPARTICLES

В работе впервые было исследовано влияние наночастиц серебра на люминесценцию иттрий-алюминиевого граната, легированного церием. С помощью метода химического восстановления был синтезирован золь с размером наночастиц серебра ≈100 нм. Керамический порошок люминофора иттрий-алюминиевого граната, легированного церием, был получен методом двухстадийного осаждения в уротропин. Золь наночастиц серебра в концентрациях от 0,125 до 0,1 мл вводили в порошок-прекурсор перед прокаливанием. Было показано, что при данном способе введения наночастиц серебра интенсивность фотолюминесценции возрастала по сравнению с эталоном. Оптимальной концентрацией в рамках исследования являлась концентрация 0,25 мл. При данной концентрации увеличение интенсивности фотолюминесценции на длине волны 540 нм составило порядка 10%. Проведенные исследования показали, что наночастицы серебра могут с успехом применяться для увеличения яркости люминофора иттрий-алюминиевого граната, легированного церием, без искажения и ухудшения спектральных характеристик. This work was the first to study the effect of silver nanoparticles on the luminescence of cerium doped yttrium-aluminum garnet. A sol with the size of silver nanoparticles of ≈100 nm was synthesized using the method of chemical reduction. Phosphor ceramic powder of the yttrium-aluminum garnet doped with cerium was obtained by the two-stage precipitation method. The silver nanoparticles sol was introduced into the precursor powder before calcination in concentrations from 0,125 to 0,1 ml. It was shown that the photoluminescence intensity increased in comparison with the reference when we used this method of introducing silver nanoparticles. The optimal concentration within the study was 0,25 ml. At this concentration, the increase in the photoluminescence intensity at a wavelength of 540 nm was about 10 %. Studies have shown that silver nanoparticles can be successfully used to increase the brightness of the phosphor of the yttrium-aluminum garnet doped with cerium without distortion and deterioration of spectral characteristics.

Luminescence efficiency of cerium-doped yttrium aluminum garnet ceramics formed by radiation assisted synthesis

The variety of applications of yttrium-aluminum garnet (YAG)-based luminescent materials and the morphology necessary for these purposes required the development of many technologies for their synthesis. All synthesis technologies used are complex. The structural phase of yttrium-aluminum garnet is formed with any technology, at temperatures exceeding 1,500 °C. The starting materials for the synthesis are metal oxides of aluminum, yttrium and other oxides for activation and modification. It seems possible to use hard radiation to form a new phase. Radiation synthesis of ceramics is realized in less than 1 s, without the use of any additives and influences. The synthesis was carried out at the electron accelerator of the Institute of Nuclear Physics (Novosibirsk). In this work, we studied the spectral-kinetic and quantitative characteristics of luminescence for the first time obtained by the method of radiation synthesis of ceramic samples of yttrium-aluminum garnet doped with cerium with statistical processing of their values. The dependences of the reproducibility of the spectral characteristics of the luminescence of the samples on the preliminary preparation of the charge for synthesis have been investigated. Several cycles of luminophore brightness studies have been performed. It is shown that the obtained ceramics based on yttrium-aluminum garnet doped with cerium possesses the required spectral-kinetic properties, and the efficiency of conversion of the chip radiation into luminescence is achieved, which is comparable to that available in commercial phosphors. The maximum measured values of the position of the bands are from 553.5 to 559.6 nm. Brightness values range from 4,720 to 1,960 cd/m2. It was found that the main reason for the scatter in the characteristics of the luminescent properties of ceramics of yttrium-aluminum garnet, activated by cerium obtained by radiation assisted synthesis is the high rate of synthesis and, especially, the high rate of cooling of the samples.

Dosimeter Based on YAG: Ce Phosphor via Sol-Gel Method for Online X-ray Radiation Monitoring

This paper focuses on the preparation of cerium-doped yttrium aluminum garnet (YAG: Ce) powder with several concentration gradients via the sol-gel method by detecting its structural characteristics via X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) to verify the generation of a complete crystal phase and evenly distributed nanopowder. On this basis, the luminescence characteristics of Ce3+ are explored, the mechanism and model are discussed based on the spectra, and the ideal doping concentration was obtained by comparing the luminescence intensity along with the fluorescence quenching theory and fluorescence decay spectra of samples with different doping concentrations. Several radiation dosimeters based on YAG: Ce phosphors were made; the online radiation monitoring function was realized under the exposure of a standard X-ray source; the repeatability, accuracy, and sensitivity of the system were verified by experiments; and the factors affecting dosimeter response are discussed. This paper verifies the possibility of adhibiting YAG: Ce fluorescent powder for online X-ray monitoring, and lays the foundation for further research.

Antifungal Activity of a Neodymium-Doped Yttrium Aluminum Garnet 1,064-Nanometer Laser against Sporothrix globosa by Inducing Apoptosis and Pyroptosis via the NLRP3/Caspase-1 Signaling Pathway: In Vitro and In Vivo Study

Nd:YAG 1,064-nm laser irradiation is a useful alternative for the treatment of sporotrichosis, especially in patients with liver dysfunction, pregnant women, and children, for whom the administration of antifungal drugs is not suitable. It may improve the overall treatment effect by shortening the duration of antifungal treatment and reducing tissue inflammation.

Hydroxyapatite Film Coating by Er:YAG Pulsed Laser Deposition Method for the Repair of Enamel Defects

There are treatments available for enamel demineralization or acid erosion, but they have limitations. We aimed to manufacture a device that could directly form a hydroxyapatite (HAp) film coating on the enamel with a chairside erbium-doped yttrium aluminum garnet (Er:YAG) laser using the pulsed laser deposition (PLD) method for repairing enamel defects. We used decalcified bovine enamel specimens and compacted α-tricalcium phosphate (α-TCP) as targets of Er:YAG-PLD. With irradiation, an α-TCP coating layer was immediately deposited on the specimen surface. The morphological, mechanical, and chemical characteristics of the coatings were evaluated using scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray diffractometry (XRD), and a micro-Vickers hardness tester. Wear resistance, cell attachment of the HAp coatings, and temperature changes during the Er:YAG-PLD procedure were also observed. SEM demonstrated that the α-TCP powder turned into microparticles by irradiation. XRD peaks revealed that the coatings were almost hydrolyzed into HAp within 2 days. Micro-Vickers hardness indicated that the hardness lost by decalcification was almost recovered by the coatings. The results suggest that the Er:YAG-PLD technique is useful for repairing enamel defects and has great potential for future clinical applications.

Aiming to the superior of phosphor pattern: Influence of SiO2 nanoparticles on photoluminescence intensification of YAG:Ce

<span lang="EN-US">Yttrium aluminum garnet (YAG: RE) rare-earth-doped phosphors have great photoluminescence (PL) characteristics and are commonly used in light-emitting rectifying tubes. The RE elements used in these phosphors, however, are precious and in shortage. The production of phosphorus containing a limited amount of RE content is therefore essential. One solution is to manufacture Nano composite phosphors that use an inexpensive and more easily available content as a matrix for RE oxide. In this research, we developed a YAG: Ce/SiO2 Nano composite using a sol-gel procedure; in order to impulse micelle formation and agglomeration, poly (ethylene glycol) and urea have been added, respectively. X-ray diffraction, scanning and transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy were used to characterize the Nano composites. In proposing an explanation for this enhancement, we defined the concentration of SiO2 that produced optimum PL enhancement and used geometric models as well as the characterization consequences. Our results demonstrated that a 10% SiO2 concentration produced a 120% PL intensity of pure YAG:Ce. TEM analysis revealed that SiO2 nanoparticles filled the voids between the YAG:Ce crystals' single grain borders, hence inhibiting light scattering, resulting in increased PL. This procedure would be beneficial for the synthesis of low-RE and high-PL phosphors on a wide scale.</span>

Surgical Technique of Supine Percutaneous Nephrolithotomy in Children

Percutaneous nephrolithotomy (PCNL) in children has become more widely used due to its high efficacy and safety and to the development of miniaturized instruments. A supine approach is promising due to advantages such as better ventilation, reproducibility, and ergonomics. The purpose of the present study is to describe our surgical technique with special considerations in the pediatric population. We used an oblique supine position supported by one silicone gel positioning pad under the hip and another under the ipsilateral flank. The anatomical landmarks used to guide the puncture were the 11th and 12th ribs, the posterior axillary line, and the iliac crest. Initially, a ureteral catheter was introduced endoscopically. A retrograde pyelography was performed to guide the puncture, which was performed using a biplanar technique. A hydrophilic guide wire was then advanced through the needle. Dilation was performed with Alken telescopic dilators until 14 Ch. Fragmentation was performed either with a 13 Ch semirigid cystoscope or a flexible ureteroscope using a holmium: yttrium aluminum garnet (Ho:Yag) laser. We left a double J catheter. Supine PCNL in the pediatric population has comparable efficacy in terms of stone free rate to that of the prone approach as well as less complications. Certain considerations in children are careful padding and placement of the patient close to the edge of the table. Puncture should be guided by ultrasound to reduce radiation exposure. Miniaturized equipment is not widely available, so adaptation of adult equipment for the pediatric population is sometimes necessary.