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- 2019
- Titanium Dioxide Nanaoparticles
- Hep-2 cell line
- Mitotic Index
- Q-switched pulsed Nd:YAG laser
- Chromosomal Aberration
- Blastogenic Index
- Applied Physics
- University of Technology (UOT)
- Al-Farahidi University
- Al-Nisour University Collage
- Al-Rafidain University Collage
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Pulse-diode-intermittent-pumped 2-μm acousto-optically Q-switched Tm:YAG laser
摘要： An innovative pulse-diode-intermittent-pumped 2-micron acousto-optically Q-switched Tm:YAG laser is presented for the first time, which can improve the output energy, while ensuring the operation repetition of laser. Maximum output energy of 6.83 mJ and minimum pulse width of 367.7 ns at Q-switched repetition rate of 200 Hz is obtained at pump energy of 86.2 mJ. The output wavelength is 2014.9 nm. The beam quality factor Mx2 is 1.59. The stability is larger than 98%.
关键词： Q-switch,Diode-pumped lasers,Tm:YAG
更新于2025-11-28 14:24:03
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Silica-coating of nano-$$\hbox {Y}_{3} \hbox {Al}_{5} \hbox {O}_{12}{:}\hbox {Ce}^{3+}$$Y3Al5O12:Ce3+ synthesized by self-combustion
摘要： Y2.91Ce0.09Al5O12 is obtained by self-combustion, grinding and sol–gel coating. X-ray diffraction, transmission electron microscopy, photoluminescence and absorption measurements were used to identify the structural and optical properties of each step of the process. The process is composed of a combination of chemical and physico-chemical processes including combustion and thermal steps, followed by grinding, powder dispersion by acidic passivation, stabilization of particle dispersions with citrate ligands and embedding of yttrium aluminium garnet (YAG) particles into SiO2 shells using a seeded growth process before drying. The initial state of the obtained powder is composed of 35 nm crystallites, sintered and agglomerated. The grinding step breaks the sintered bridge, while the passivation and citrate adsorption steps separate the particles by electrostatic repulsion before the silica coating. The optical characterizations are performed and compared separately for the powdered samples that represent the initial and ?nal states of our process, and the dispersion sample represents the intermediate state of our process. The optical measurement revealed an important amount of optical defects at the surface of the particles, compared with micrometric commercial particles. The grinding, nitric acid and citrate steps remove some of these defects. The ?nal state of the sample still possesses lower quantum ef?ciency than that of a micrometric sample, but the SiO2 coating allows for a perfect separation of the particle, suitable for implementation in small devices.
关键词： Self-combustion,YAG,core–shell,SiO2 coating
更新于2025-09-23 15:23:52
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Enhanced optical properties of YAG:Ce yellow phosphor by modification with gold nanoparticles
摘要： In this paper methods of synthesis and characterization of cerium doped yttrium aluminum garnet (YAG:Ce) and the improvement of properties by in situ modification using gold nanoparticles are presented. YAG:Ce phosphor was obtained by cations co-precipitation followed by thermal treatment at 1000 °C, while for the development of the Au-YAG:Ce nanocomposites, the Turkevich method was used. The quality of the phosphor particles and composite has been structurally, morphologically and optically studied. It has been emphasized the obtaining of high purity phosphor and maintenance of the YAG:Ce garnet structure after modifying the phosphor surface with gold nanoparticles. Also, the use of gold nanoparticles has led to improvements in optical and morphological properties as a result of lowering the agglomeration trend. Improvement of optical properties makes possible the use of Au-YAG:Ce composite thus developing low energy light sources and with high performance.
关键词： YAG:Ce,Au-YAG:Ce composite,Optical materials,Phosphor
更新于2025-09-23 15:22:29
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Residual porosity and optical properties of spark plasma sintered transparent polycrystalline cerium-doped YAG
摘要： Transparent cerium-doped yttrium aluminum garnet (Ce:YAG) phosphors are promising candidates for high-power white light emitting diode applications. In the present study, Ce:YAG powder was synthesized by a co-precipitation method and highly transparent ceramics were fabricated by spark plasma sintering. The effects of temperature and pressure, as well as post-sintering treatments (annealing or hot isostatic pressing), on residual porosity were studied by electron and confocal laser microscopy. Correlation between residual porosity characteristics (pore size and volume fraction) and optical properties (in-line transmittance and photoluminescence intensity) of the luminescent transparent ceramics was established.
关键词： Transparency,Spark plasma sintering,Photoluminescence,Ce:YAG ceramic,Residual porosity
更新于2025-09-23 15:21:21
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Disinfection of Contaminated Metal Implants with an Er:YAG Laser
摘要： Infections related to orthopedic procedures are considered particularly severe when implantation materials are used, because effective treatments for biofilm removal are lacking. In this study, the relatively new approach for infection control by using an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser was tested. This laser vaporizes all water containing cells in a very effective, precise, and predictable manner and results in only minimal thermal damage. For preliminary testing, 42 steel plates and 42 pins were seeded with mixed cultures. First, the minimally necessary laser energy for biofilm removal was determined. Subsequently, the effectiveness of biofilm removal with the Er:YAG laser and the cleansing of the metal implants with octenidine‐soaked gauze was compared. Then, we compared the effectiveness of biofilm removal on 207 steel pins from 41 patients directly after explantation. Sonication and scanning electron microscopy were used for analysis. Laser fluences exceeding 2.8 J/cm2 caused a complete extinction of all living cells by a single‐laser impulse. Cleansing with octenidine‐soaked gauze and irradiation with the Er:YAG laser are both thoroughly effective when applied to seeded pins. In contrast, when explanted pins with fully developed biofilms were analyzed, we found a significant advantage of the laser procedure. The Er:YAG laser offers a secure, complete, and nontoxic eradication of all kinds of pathogens from metal implants without damaging the implant and without the possible development of resistance. The precise noncontact removal of adjacent tissue is a decisive advantage over conventional disinfectants. Therefore, laser irradiation could become a valuable method in every debridement, antibiotics, and implant retention procedure.
关键词： implant‐related infection,DAIR,Er:YAG laser,laser disinfection,pin‐tract infection,biofilm removal
更新于2025-09-23 15:21:01
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Treatment of psoriatic skin lesions with a new Er:Yag laser technology: A case series study
摘要： Erbium: YAG (Er:YAG) laser with RecoSMA technology. This laser emits thousands of microbeams of energy causing superficial epidermal ablation and a separation of dermal fibers due to a mechanical-acoustic and resonance effect. The aim of this study is to evaluate the clinical efficacy of Erbium: YAG (Er:YAG) laser with RecoSMA in the treatment of stable psoriasis vulgaris lesions. A questionnaire completed by 112 patients enrolled in the study. Photographs taken before each session, the analysis of the dynamics index PASI and histological studies were analyzed to visually monitor the clinical progress. The analyses were carried out with the help of computer software. The results after treatment of average number of sessions per course showed the complete clinical remission of the skin lesions in over 87% of the patients treated. The Er:YAG laser and RecoSMA have demonstrated the high effectiveness of the laser method of treating skin manifestations of the disease and improving the quality of life of patients.
关键词： Er:YAG,mechanical-acoustic effect,laser,PASI index,RecoSMA technology,psoriasis vulgaris,space-modulated ablation
更新于2025-09-23 15:21:01
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YAG:Ce <sup>3+</sup> Transparent Ceramic Phosphors Brighten the Next-Generation Laser-Driven Lighting
摘要： Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic phosphors (TCPs) are regarded as the most promising luminescent converter for laser-driven (LD) lighting. High-quality YAG:Ce3+ TCPs are still urgent for high efficiency LD lighting devices. YAG:Ce3+ TCPs in a vacuum ambience by using nano-sized raw materials are prepared. Controlling defects by adding nano-sized MgO and SiO2 simultaneously enables a high transmittance nearly 80%. After annealing in air furthermore, the luminous efficiency is enhanced greatly from 106 to 223 lm W?1, which is the best result reported now for LD lighting. These results demonstrate that the optimizing YAG:Ce3+ TCPs in a fitting strategy will brighten once again in the next-generation LD lighting. Based on scanning electron microscopy (SEM) coupled with a cathodoluminescence system, defects and Ce3+ distributions in grains are identified directly for the first time.
关键词： cathodoluminescence,laser-driven lighting,transparent ceramic phosphors,Mg2+–Si4+,YAG:Ce3+
更新于2025-09-23 15:21:01
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Efficacy of microneedling versus fractional Er:YAG laser in facial rejuvenation
摘要： Background: Microneedling and fractional lasers have been used in facial rejuvenation with acceptable results and low adverse effects. Aims: To compare the efficacy of microneedling with fractional Er:YAG in facial skin rejuvenation. Patients/Methods: This study was planned as a split-face clinical trial. Volunteers were randomly allocated to receive three monthly treatments on each side of the face, one with fractional Er:YAG laser and one with microneedling. The assessments included investigating clinical outcomes by two blinded dermatologists accompanied by measuring skin biophysical characteristics including cutaneous resonance running time (CRRT) and transepidermal water loss (TEWL). Moreover, possible adverse effects, downtime, and patients' satisfaction were recorded at baseline, 1 month after each treatment, and 3 months after the last treatment session. The protocol was approved by the Iranian Registry of Clinical Trials (IRCT20160820029436N3). Results: Of the 32 selected volunteers, 24 subjects completed the study. The clinical assessment showed a significant improvement of the face appearance along with a significant reduction in dyschromia, and periorbital wrinkling (P-value < .05), with both procedures without any considerable difference between two methods. Moreover, the patients showed substantial satisfaction with both modalities with no statistically significant difference. Mean TEWL and CRRT values also decreased significantly in both groups with no considerable difference. The downtime was significantly shorter in the microneedling-treated side. There were no long-lasting or severe adverse effects after treatment with both methods. Conclusion: Microneedling and fractional Er:YAG laser have comparable efficacy in facial rejuvenation, but little downtime of the former makes it preferable for many patients.
关键词： facial rejuvenation,fractional Er:YAG laser,wrinkle,microneedling
更新于2025-09-23 15:21:01
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High-peak-power and narrow-linewidth Q-switched Ho:YAG laser in-band pumped at 1931 nm
摘要： We describe a high-peak-power, narrow-linewidth Q-switched Ho:YAG laser at 2097 nm wing-pumped by a high power and high brightness Tm:fiber source at 1931.5 nm. The laser was wavelength locked and spectrum narrowed utilizing a volume Bragg grating as the input coupler, resulting a linewidth (FWHM) of less than 0.1 nm. At 22.7 W of incident pump power, stable pulses of 5.5 mJ pulse energy and 17.5 ns of pulse duration have been generated at repetition frequency of 1 kHz, corresponding to peak power of 314.3 kW.
关键词： narrow-linewidth,Q-switched Ho:YAG laser,volume Bragg grating,1931.5 nm,high-peak-power
更新于2025-09-23 15:21:01
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Effect of the Ce3+ concentration on laser-sintered YAG ceramics for white LEDs applications
摘要： This paper describes the laser sintering and luminescence properties of Y3Al5O12 (YAG) phosphors doped with different concentrations of Ce3+ and synthesized using the polymeric precursor method. The ceramics were sintered by a new laser sintering technique in which a CO2 laser is employed as the heating source. The resultant ceramics exhibited a homogeneous microstructure with narrow grain size distribution and high relative density. The introduction of Ce3+ ions led to luminescence quenching at a concentration above 0.5 mol% and a redshift of the emission spectrum band with increasing cerium concentration. The excitation spectrum showed two characteristic bands centered at 340 nm and 460 nm and a relative change in their intensity by change the Ce3+ concentration. The presence of a single valence (Ce3+) of cerium was determined by X-ray absorption near edge structure measurements.
关键词： laser sintering,ceramics,photoluminescence,LED,YAG
更新于2025-09-23 15:21:01