Pulsed Neodymium-doped Yttrium Aluminum Garnet Research Articles

The Influence of Neodymium-Doped Yttrium Aluminum Garnet Laser Pulse Repetition Rate on Cytokine Secretion from Peripheral Blood Mononuclear Cells in Vitro

Objective: Biological effects of infrared laser energy at various exposure parameters have been characterized in previous in vitro and animal studies. However, the impact of pulse repetition rate (PRR) has not been evaluated in this context. The purpose of this investigation was to assess the influence of PRR on cytokine secretion from peripheral blood mononuclear cells (PBMCs) subjected to pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser energy. Materials and Methods: Rat PBMCs were cultured in vitro then stimulated using a lipopolysaccharide concentration of 0 or 100 ng/ml. Cultures received Nd:YAG laser radiation (1064 nm, 5 W, 30 s) at PRR of 0 (untreated controls), 20, 30, 40, or 60 Hz. Concentrations of tumor necrosis factor-α (TNF-α), macrophage inflammatory protein (MIP)-1α, macrophage inflammatory protein (MIP)-2, monocyte chemoattractant protein-1 (MCP-1), interferon-gamma-induced protein (IP)-10, interleukin (IL)-6, and IL-10 were recorded using a magnetic microsphere immunoassay. The main effects of PRR and LPS stimulation on cytokine concentrations, and the interaction between PRR and LPS stimulation, were assessed using two-way analysis of variance. Bonferroni post hoc tests were used to identify pairwise differences between groups. Results: The main effect of PRR was statistically significant for MIP-1α (P = 0.018), TNF-α (P = 0.025), MCP-1 (P < 0.001), MIP-2 (P = 0.013), and IL-6 (P = 0.031). Five of six pro-inflammatory cytokines exhibited significantly lower mean concentrations in laser-exposed compared with control cultures at one or more PRR. However, no statistically significant differences were found between PRR groups. Conclusions: Under the described conditions, statistically significant differences in cytokine secretion were observed between laser-exposed and control cultures, consistent with prior reports. However, PRR appears to be an irrelevant factor in immunomodulation of PBMCs.

Hair removal prior to treating port-wine stain blebs with long pulsed neodymium-doped yttrium aluminum garnet laser

Hair removal prior to treating port-wine stain blebs with long pulsed neodymium-doped yttrium aluminum garnet laser

Increasing the Corrosion Resistance in the UNS S32750 Super Duplex Steel Welded Joints through Hybrid GTAW-Laser Welding and Nitrogen.

The development of techniques to improve the welding of super duplex steels is necessary in order to ensure that the phase balance and properties of the material are not affected during this process. Hybrid arc-laser welding is a perfect combination of the advantages of both processes, producing deeper weld beads with more balanced phases than the pulsed laser process. Here, the objective was to improve the corrosion resistance of UNS S32750 weld beads by increasing the volumetric austenite percentage in the fusion zone (FZ) with a hybrid process of GTAW (gas tungsten arc welding) and pulsed laser Nd-YAG (neodymium-doped yttrium aluminum garnet). Welds were performed in bead on plate conditions with fixed laser parameters and a varying heat input introduced through the GTAW process. Additionally, welds within a nitrogen atmosphere were performed. After base metal characterization, an analysis of the FZ and heat affected zone were performed with optical microscopy, scanning electron microscopy and critical pitting tests (CPT). The synergy between the thermal input provided by the hybrid process and austenite-promoting characteristic of nitrogen led to a balanced volumetric austenite/ferrite fraction. Consequently, the results obtained in CPT tests were better than conventional welding processes, such as laser or GTAW solely.

Портативный нейтронный генератор на лазерно-плазменном ионном диоде с магнитной изоляцией

The article presents a new experimental portable pulsed neutron generator based on a laser-plasma ion diode with magnetic insulation and the results of the first experiments. The laser-plasma diode makes it possible to obtain large ion current pulses that generate high-intensity neutron radiation. The source of optical radiation was a pulsed neodymium-doped yttrium aluminum garnet laser with a wavelength of 1064 nm, a pulse energy of up to 0.7 J, and a duration of ~10 ns. The ion beam is accelerated by an Arkadiev-Marx pulsed voltage generator with a voltage amplitude of up to 250 kV, a duration of up to 1.5 µs, and an energy of up to 160 J. Neutrons were generated using the reaction d(d,n)3He. A neutron yield of 2·107 neutron/pulse was obtained.

Quantitative analysis of uranium in electro-recovery salt of pyroprocessing using laser-induced breakdown spectroscopy

The amounts of nuclear materials in the LiCl-KCl salt in pyroprocessing have to be analyzed to prevent the diversion of the nuclear material. An alternative method to the chemical analysis has been pursued, and laser-induced breakdown spectroscopy (LIBS) is one candidate. In the present work, an in situ and quantitative analysis method of electro-recovery (ER) salt was proposed and demonstrated by using LIBS combined with dipstick sampling. Two types of simulated salt samples were prepared: ER salt sample and salt obtained from the dipstick sampling, and pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with a wavelength of 532 nm was focused on the salt to generate plasma. The plasma emission was measured by using an Echelle spectrometer with a resolution of 0.01 nm in conjunction with an Intensified Charge-Coupled Detector camera. The U and other rare earth peaks in the spectra were identified. The best Limit of Detection and Root Mean Square Error of Calibration of U were 38 ppm and 0.0203 wt%, respectively. Our work shows that the U in the pyroprocessing ER salt can be monitored with LIBS.

Immediate effect of pulsed high-intensity neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on staphylococcus aureus and pseudomonas aeruginosa growth: an experimental study

[Purpose] The aim of this study was to evaluate the effect of pulsed high intensity neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on staphylococcus aureus (S. aureus) and pseudomonas aeruginosa (P. aeruginosa) bacterial growth, which cause many health problems and establish which doses are effective in bacterial inhibition. [Materials and Methods] Five samples of S. aureus and five samples of P. aeruginosa were prepared in the microbiology lab, one used as control sample and the other 4 samples acted as experimental samples. The experimental samples received pulsed high intensity Nd: YAG laser with a total dose of 500, 600, 700 and 800 joules. The primary measures are colony count and the percentage decrease in colony count, the colony count was assessed at baseline and after 24 h of laser application. [Result] There was significant decrease in colony count and the percentage decrease in colony count after pulsed high intensity Nd: YAG laser application in all experimental samples of S. aureus and P. aeruginosa after 24 h of application for all doses (500, 600, 700 and 800 j) as compared with the control sample, with the most effect in higher doses of pulsed high intensity Nd: YAG laser than lower doses in both types of bacteria. [Conclusion] pulsed high intensity Nd: YAG laser was found to be an effective modality for inhibition of S. aureus and P. aeruginosa growth after a single application.

A comparative study on thermally and laser annealed copper and silver doped CdTe thin film solar cells

Copper (Cu) and silver (Ag) are the potential dopants that could enhance p-type doping of polycrystalline cadmium telluride (CdTe) thin films to be used in CdTe based solar cells. In this work, the effect of doping concentration of Ag and Cu in both thermal and laser anneal process of doping to CdTe thin film solar cells’ electrical performance were investigated. CdTe thin films of 3 µm thickness were deposited using the close-spaced sublimation (CSS) process and subjected to Cu and Ag doping process through dip coating in copper (II) chloride (CuCl2) and silver nitrate (AgNO3) solution, respectively at different concentration range followed by either thermal or laser annealing. Thermally annealed CdTe thin films were treated in convection oven, whereas laser annealing was carried out by illuminating the samples with pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser at wavelength of 532 nm. Fabricated solar cells were electrically characterized by light current-voltage (J-V) and capacitance-voltage (C-V) measurements. J-V measurement demonstrates that Cu doped CdTe solar cells are having better electrical performance as compared to Ag doped ones. The effect of increasing dopant solution concentrations seems to have consistent trend with the increase of J-V parameters as identified in this work. C-V measurement shows that Cu doped CdTe films has higher doping capability with the highest acceptor concentration of 1.5 × 1014 cm−3 compared to Ag doped CdTe films of 8.1 × 1013 cm−3. In addition, laser annealing finds lower J-V performance and acceptor concentration of Cu and Ag doped CdTe solar cells with limitations in smaller process space for surface annealing as well as optimization.

Long-Term Effect of Pulsed Nd:YAG Laser in the Treatment of Children with Juvenile Rheumatoid Arthritis: A Randomized Controlled Trial.

The aim of this study was to evaluate the long-term impact of a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser [high-intensity laser therapy (HILT)] in the treatment of juvenile rheumatoid arthritis (JRA). A sample of 30 children participated in this study (15 in the laser group and 15 in the placebo group), with a mean age of 10.53 ± 1.25 years. Children who were randomly assigned to the laser group received HILT thrice per week for 4 weeks, plus the exercise program. HILT scanned each knee with 600 J in two phases and 15 J to 10 points for a total of 750 J for each knee. The placebo laser group received placebo HILT plus the same exercise program. The outcomes measured in this study were the pain level by the visual analog scale (VAS) and gait parameters by the GAITRite® system. Statistical analysis was performed by ANOVA with repeated measures to compare the differences between the baseline, post-treatment, and 12-week follow-up measurements for both groups. The level of significance was set at p < 0.05. The VAS results significantly decreased post-treatment in the laser group relative to the placebo group and were still improved at the 12-week follow-up. Gait parameters significantly increased in the laser group after 4 weeks of treatment and after 12 weeks compared to the placebo group. HILT, when combined with an exercise program, appears to be more effective in children with JRA than a placebo laser procedure with exercises.

Optimizing laser crater enhanced Raman spectroscopy.

Raman signal enhancement by laser crater production was systematically studied for 785nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532nm, 8ns, 1mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Double Q-switched 946 nm laser with MgO:LN electro-optic crystal and MoSe2 saturable absorber

We report a double Q-switched 946 nm laser with a magnesium-oxide-doped LiNbO3 (MgO:LN) electro-optic (EO) crystal and a monolayer molybdenum diselenide (MoSe2) saturable absorber (SA). A pulsed laser diode side-pumped long neodymium-doped yttrium aluminum garnet rod (φ3×65 mm) is used as the gain medium. Large pulse energy up to 3.15 mJ and peak power up to 346 kW are generated at the repetition rate of 550 Hz, corresponding to the beam quality factors of Mx2=3.849, My2=3.868. Monolayer MoSe2 nanosheets applied in the experiment would be a promising SA for a passive Q-switching operation.

Laser Irradiation Responses of a Single-Crystal Diamond Produced by Different Crystal Growth Methods

Responses of two types of single-crystal diamonds, prepared by chemical vapour deposition (CVD) and high pressure high temperature synthesis (HPHT) methods, respectively, to a nanosecond pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser were investigated and compared. It was found that due to the difference in the transmission rate and refractive index, the laser-induced surface/subsurface features of the two types of samples were distinctly different. For the CVD sample, destructive interference takes place on the upper surface, leading to direct ablation of smooth grooves with deposition of graphite. For the HPHT sample, however, laser-induced grooves were formed on the reverse side of the irradiation surface (namely, the lower surface) at certain laser fluences due to the constructive interference phenomenon of the laser and the high refractive index of the material. The reverse-side irradiation resulted in the formation of deep and sharp grooves with rough bottoms and insignificant deposition of graphite on the area surrounding the groove. The machining thresholds for the upper and lower surfaces of both types of diamonds were experimentally obtained and theoretically verified. The findings of this study provide important process criteria for laser machining of different kinds of diamonds. The reverse-side irradiation method enables efficient machining of deep grooves in diamonds using a lower power laser.

Demonstration of an iron fluorescence lidar operating at 372 nm wavelength using a newly-developed Nd:YAG laser.

We report on the development of a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at a 1116nm wavelength. Because the third harmonic is within a few gigahertz of the 372nm absorption line of iron, this laser system represents an alternative to alexandrite lasers commonly used in iron fluorescence lidars. With our prototype, we achieved a 0.5W at 372nm wavelength and a 100Hz pulse repetition frequency. As a proof of concept, we show iron density measurements, which have been acquired using the novel lidar transmitter.

Rapid Detection of Oil Pollution in Soil by Using Laser-Induced Breakdown Spectroscopy

Detection of oil pollution in soil has been carried out using laser-induced breakdown spectroscopy (LIBS). A pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1,064 nm, 8 ns, 200 mJ) was focused onto pelletized soil samples. Emission spectra were obtained from oil-contaminated soil and clean soil. The contaminated soil had almost the same spectrum profile as the clean soil and contained the same major and minor elements. However, a C–H molecular band was clearly detected in the oil-contaminated soil, while no C–H band was detected in the clean soil. Linear calibration curve of the C–H molecular band was successfully made by using a soil sample containing various concentrations of oil. The limit of detection of the C–H band in the soil sample was 0.001 mL/g. Furthermore, the emission spectrum of the contaminated soil clearly displayed titanium (Ti) lines, which were not detected in the clean soil. The existence of the C–H band and Ti lines in oil-contaminated soil can be used to clearly distinguish contaminated soil from clean soil. For comparison, the emission spectra of contaminated and clean soil were also obtained using scanning electron microscope-energy dispersive X-ray (SEM/EDX) spectroscopy, showing that the spectra obtained using LIBS are much better than using SEM/EDX, as indicated by the signal to noise ratio (S/N ratio).

Effect of the filler amount on the optical absorption properties and the surface features of polymeric joints based on biomedical UHMWPE welded by a Nd:YAG laser

Polymeric materials can be welded by the laser transmission welding technique in order to join two or more sheets. At the interface of the polymer sheets, the released energy induces melting that is assisted by pressure, producing a fast and resistant welding. In this research, single-lap polymeric joints of biomedical ultra-high molecular weight polyethylene sheets were realized; one of the two polymer sheets was doped, at different concentrations, with carbon nanomaterials as a laser absorbent filler. A pulsed neodymium-doped yttrium aluminium garnet laser operating in the wavelength of 532 nm and of 1064 nm with an intensity of the order of 109 W/cm2 was employed to obtain a joint at the interface between the transparent polymer and the absorbent one. The mechanical shear resistance of the prepared joints was related to the optical absorption feature of the polymeric materials. Besides, surface analyses such as hardness, roughness and wettability in different inorganic and organic fluids were presented and discussed. The result of characterization analyses indicated the best filler amount in order to have a mechanically resistant joint with surface properties also suitable for the biomedical employment.

Gain-switched Ti:sapphire laser-based photoacoustic imaging.

We demonstrate photoacoustic (PA) imaging using a compact gain-switched Ti:sapphire laser. Additionally, a simple laser configuration is provided. The Ti:sapphire laser is pumped using a frequency-doubled pulsed neodymium-doped yttrium aluminum garnet pulse laser operating at a repetition rate of 10Hz, with a pump energy of 37mJ. No water cooling is required for the Ti:sapphire crystal. The output pulse energy and pulse duration of the laser are 13.6mJ and 11ns, respectively. Thus, the power conversion efficiency is 36.7%. As the end mirror in a laser cavity is adjusted in a horizontal direction, the output wavelength can be tuned within a range of 725-880nm with a spectral bandwidth of approximately 1nm. The laser has a small footprint size of 50 cm×35 cm including even laser pumping. Because the near-infrared region has significant advantages in the context of absorption and scattering in biological tissues, our laser can be used for PA imaging. Apart from obtaining PA images of a tube filled with indocyanine green immersed in water and placed under chicken breast tissue, our laser system could also be used for the simultaneous PA and ultrasound (US) dual-modality imaging of blood vessels lying beneath the skin of a human middle finger. We used a commercially available US machine for the PA and US dual-modality imaging.

Laser Therapy for an Acquired Glomuvenous Malformation (Glomus Tumour): A Nonsurgical Approach.

Glomuvenous malformations (GVMs) (previously known as glomus tumours) are uncommon, benign, vascular neoplasms. Current treatments include surgical excision and sclerotherapy, often with high recurrence rates and poor cosmetic results. We sought to use a nonsurgical approach for treatment of a GVM. We present a patient with an acquired, biopsy-proven GVM of the heel unamenable to surgical excision, treated with a long pulsed 1064-nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Excellent cosmesis and long-term remission were achieved after several treatment sessions. Our experience provides further evidence to support the safety and effectiveness of the 1064-nm Nd:YAG laser in the management of large and surgically challenging GVMs.

Laser lift-off technique for freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN and its application to light-emitting diodes

We developed a laser lift-off technique for a freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN. A combination of an In droplet formed by thermal decomposition of GaInN during growth and a pulsed second-harmonic neodymium-doped yttrium aluminum garnet laser (λ = 532 nm) realized the lift-off GaN substrate. After laser lift-off of the GaN substrate, it was used to achieve 380 nm ultraviolet light-emitting diodes with light output enhanced 1.7-fold. In this way, the light extraction can be improved by removing the GaN substrate.

Temporal pulse shaping: a key parameter for the laser welding of dental alloys.

This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80% overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity.

The Use of Long Pulsed Neodymium-Doped Yttrium Aluminum Garnet for the Treatment of Paediatric Venous Malformations

BackgroundVenous malformation in the pediatric population can present with pain, bleeding, or a debilitating deformity that can be difficult to manage. Sclerotherapy, surgery, and more recently, long pulsed neodymium-doped yttrium aluminum garnet (Nd : YAG) laser have been used with variable success rates.ObjectiveOur aims and objectives, were to identify the specific group of patients that would benefit from this treatment.MethodsA prospective clinical trial was carried out with 59 consecutive patients. The treatment criteria included a large facial deformity and painful or bleeding lesions. One to three treatments were administered at 6~8-week intervals.ResultsA total of 59 patients were treated. The average follow-up was 24 months. All patients achieved good to excellent results in pain and bleeding control as well as in the reduction of the size of lesions in the lip and oral mucosa. The treatment however, is not effective in reducing the size of large, relatively high-flow lesions in the limbs. Complications from treatment include skin blistering (n=4), ulceration (n=4), and subsequent hypertrophic scarring (n=3). Three patients had partial recurrence after a 3-year follow-up.ConclusionComplex venous malformations cannot be cured but can be symptomatically controlled with the long-pulsed Nd : YAG laser treatment. The treatment satisfaction is high, and there is a small but definite risk of scarring from treatment.

Significance of scaling and root planing with and without adjunctive use of a water-cooled pulsed Nd:YAG laser for the treatment of periodontal inflammation

The aim was to assess the significance of scaling and root planing (SRP) with adjunctive use of a water-cooled pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the treatment of periodontal inflammation. Thirty-nine patients were equally divided into three groups. In group 1, the upper jaw was treated with Nd:YAG laser application; whereas in groups 2 and 3, the upper jaw was treated with SRP alone and Nd:YAG laser application immediately after SRP, respectively. In each group, probing pocket depth (PPD), plaque index (PI), and gingival index (GI) were measured and gingival crevicular fluid (GCF) volume was determined after using at 1week and after 3months. Three-month follow-up results showed that PPD, PI, GI, and GCF volume were significantly reduced in group 3 compared to groups 1 and 2. In short term, SRP with a single application of a water-cooled pulsed Nd:YAG laser reduced PI, GI, PPD, and GCF volume more significantly compared to when Nd:YAG laser and SRP are used alone to treat periodontal inflammation.