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Face and neck rejuvenation using an improved non-ablative fractional high power 1064-nm Q-switched Nd:YAG Laser: clinical results in 16 women
摘要： Objective: To evaluate the safety and efficacy of a specific treatment protocol using a new and improved non-ablative fractional high-power 1064-nm Q-switched Nd:YAG laser for face and neck rejuvenation. Methods: Sixteen women, aged 30 to 60 years old, were selected to undergo three consecutive treatment sessions with this new laser at maximum energy (2,400 mJ/pulse, Clear Lift laser?-Harmony XL-Pro, Alma Lasers Ltd.). Face and neck were treated in eight patients, respectively. Each treatment used the same protocol. The efficacy was evaluated by the therapist (TS), the patient (PS), and two separate independent experts who were blind to the study (E1 and E2). Results: According to E1 and E2, the mean reduction in signs of skin aging on a Global Esthetic Improvement Scale was 30-40%. Using a 0–10 points scale, TS and PS mean (range) satisfaction rates were 9.0 (8–10); 9.2 (6–10) for the face and 8.7 (8–10); 8.0 (3–10), for the neck, respectively. The procedure was practically painless, no significant adverse effects were observed, and the patients returned to their daily and work activities without downtime. Conclusion: This laser was safe and effective for face and neck minimally invasive rejuvenation, with excellent results using our usual routine use conditions.
关键词： fractionated laser,resurfacing,Q-Switched Nd:YAG laser,Skin rejuvenation,non-ablative laser
更新于2025-09-23 15:19:57
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Characteristics of Bubble Oscillations During Lasera??Activated Irrigation of Root Canals and Method of Improvement
摘要： Background and Objectives: Laser‐activated irrigation of dental root canals is being increasingly used as its efficacy has been shown to be superior compared with conventional techniques. The method is based on laser‐initiated localized fluid evaporation and subsequent rapid bubble expansions and collapses, inducing microfluid flow throughout the entire volume of the cavity. The irrigation efficacy can be further improved if optimally delayed “SWEEPS” double laser pulses are delivered into the canal. This study aims to show that the irrigation efficacy, as measured by the induced pressure within the canal, is related to the double pulse delay, with the maximal pressure generated at an optimal delay. The second aim is to find a method of determining the optimal delay for different cavity dimensions and/or laser parameters. Study Design/Materials and Methods: Experiments were made in transparent models of root canals where Er:YAG laser (λ = 2.94 μm, pulse duration tp = 25 or 50 microseconds, and pulse energies up to EL = 40 mJ) was used with a combination of cylindrical and conical fiber‐tip geometries (diameters 400 and 600 μm). High‐speed photography (60,000 fps) and average pressure measurements inside the canal were used for process characterization. Results: The results show that a pressure amplification of more than 1.5 times occurs if the laser pulse delay approximately coincides with the bubble oscillation time. Correlations between normalized oscillation time and canal diameter for a wide range of laser pulse energies (R2 = 0.96) and between the average pressure within the canal and the bubble oscillation periods (R2 = 0.90) were found. A relationship between the bubble oscillation time and the diameter of the treated cavity was found depending on the bubble oscillation time in an infinite fluid reservoir. Conclusions: The bubble oscillation time within a constrained volume can be determined based on the known oscillation time in infinite space, which offers a fast and simple solution for optimization of the laser parameters. These findings enable determination of optimal conditions for shock wave generation, and improvement of root canal irrigation at the same dose of laser energy input, leading to improved treatment efficacy and safety.
关键词： constrained environments,cavitation bubble,irrigation,Er:YAG laser,root canals,laser‐activated,laser‐induced cavitation
更新于2025-09-23 15:19:57
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Experimental Study of the Technology Parameters Affect in the Laser Welded Joints
摘要： The laser welding technology is improving immediately rapidly nowadays. It has many advantages again the traditional welding technologies. The heat affected zone in case of the laser welding is very thin and the penetration of the joint is depth. This high energy technology work by a focused high energy laser light accompanied by protective gases. For welding process well known the different laser devices (gas laser, solid-state laser, disc laser). The effect of the gases and the technological parameters are not well known yet. In this work, we wanted to find some relationship between the welding parameters and the joint mechanical properties. To find this relationship it was welded the joint by different technologies parameters and the samples experimented the joint mechanical properties with different parameters and controlled by the experimental way.
关键词： technology parameters,Nd:YAG laser,laser welding,joint mechanical properties,CO2 laser
更新于2025-09-23 15:19:57
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Temperature changes during laser lithotripsy with Ho:YAG laser and novel Tm-fiber laser: a comparative in-vitro study
摘要： Aim The aim of this study was to compare the thermal effects of Ho:YAG and Tm-fiber lasers during lithotripsy in an in-vitro model via real-time temperature measurement. Methods We compared a Ho:YAG laser (pav up to 100 W, Lumenis, Yokneam, Israel) and a superpulse Tm-fiber laser (SP TFL, pav up to 40 W, NTO IRE-Polus, Fryazino, Russia), both equipped with 200 μm bare-ended fibers. The following settings were used: 0.2 J, 40 Hz (nominal pav 8 W). Power meter FieldMaxII-TO (Coherent, Santa Clara, CA, USA) was used to verify output laser power (pav). Each laser was fired for 60 s in two setups: (1) thermos-insulated (quasi-adiabatic) cuvette; (2) actively irrigated setup with precise flow control (irrigation rates 0, 10, 35 mL/min). Results Power measurements performed before the test revealed a 10% power drop in Ho:YAG (up to 7.2 ± 0.1 W) and 6.25% power drop in SP TFL (up to 7.5 ± 0.1). At the second step of our experiment, irrigation reduced the respective temperatures in the same manner for both lasers (e.g., at 35 mL/s SP TFL ? 1.9 °C; for Ho:YAG laser ? 2.8 °C at 60 s). Conclusion SP TFL and Ho:YAG lasers are not different in terms of volume-averaged temperature increase when the same settings are used in both lasers. Local temperature rises may fluctuate to some degree and differ for the two lasers due to varying jet streaming caused by non-uniform heating of the aqueous medium by laser light.
关键词： Ho:YAG laser,Laser lithotripsy,Thermal effect,Thulium fiber laser,In-vitro
更新于2025-09-23 15:19:57
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Evaluation of Fractional CO <sub/>2</sub> Versus Long Pulsed Nd:YAG Lasers in Treatment of Hypertrophic Scars and Keloids: A Randomized Clinical Trial
摘要： Background: Keloids and hypertrophic scars are challenging to both patients and physicians. They can be aesthetically disfiguring, functionally debilitating, and emotionally distressing. Lasers have introduced new mechanisms to improve scars both on aesthetic and symptomatic levels. Aim of Work: Comparing the efficacy of fractional CO2 laser, long‐pulsed Nd:YAG laser and their combination in the treatment of hypertrophic scars and keloids on clinical, histopathological, and biochemical basis. Patients and Methods: Thirty patients with hypertrophic scars and keloids were enrolled in the study. Three scars in each patient were randomly assigned to treatment modalities (i) Fractional CO2, (ii) Nd:YAG laser, (iii) Combined CO2 and Nd:YAG lasers. For each treatment area four sessions, 4–6 weeks apart were performed. Clinical evaluation was done before and 1 month following last session using the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS). Routine hematoxylin and eosin, Masson's trichrome, and Orcein stains were used to evaluate the appearance and pattern of dermal collagen and elastic fibers. Image analysis was used to quantitatively assess the density of collagen and elastic fibers. Biochemical evaluation of tissue level of transforming growth factor‐β I (TGF‐β I) and TGF‐β III was performed using enzyme‐linked immunosorbent assay studies. Results: Both VSS and POSAS showed significant improvement following treatment with the three used modalities. Collagen fibers showed significant improvement as regards appearance and pattern while it was insignificant as regards density. Elastic fibers density improvement was only significant in fractional CO2 (treatment area A). Hypertrophic scars showed more significant improvement with fractional CO2 laser, while in keloids there was no significant difference between the three modalities regarding improvement. Level of TGF‐β I showed significant reduction after treatment in all treatment modalities, while TGF‐β III levels showed insignificant elevation in all treatment modalities. Side effects were significantly higher in treatment area C (combined treatment). Conclusion: Long pulsed Nd:YAG laser is effective and safe treatment of hypertrophic scars and keloids. Fractional CO2 laser yields better improvement in hypertrophic scars, while in keloids both fractional CO2 and Nd:YAG lasers achieve comparable improvement. Combination in the same session did not add significant additional benefit and the side effects profile was higher. Limitations: small sample size and short follow‐up period.
关键词： fractional CO2 laser,Nd:YAG laser,keloids,hypertrophic scars,RCT
更新于2025-09-23 15:19:57
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Thermal coagulum formation and hemostasis during repeated multipulse Nd:YAG laser treatment of cutaneous vascular lesions: animal experiment study
摘要： Laser therapy has been widely used to treat port-wine stain (PWS) and other cutaneous vascular lesions via selective photothermolysis. High incident laser fluence is always prohibited in clinic to prevent the thermal damage in normal skin tissue, leading to insufficient energy deposition on the target blood vessel and incomplete clearance of PWS lesion. In this study, repeated multipulse laser (RMPL) irradiation was proposed to induce acute thermal damage to target blood vessels with low incident fluence (40 J/cm2 for 1064-nm Nd:YAG laser). The feasibility of the method was investigated using animal models. Repeated multipulse irradiation cycles with 10-min intervals were performed in RMPL. A hamster dorsal skin chamber model with a visualization system was constructed to investigate the instant generation of thermal coagulum and relevant hemostasis by thrombus formation during and after irradiation under 1064 nm Nd:YAG single multipulse laser (SMPL) and RMPL irradiation. The diameter of the target blood vessel and the size of thermal coagula were measured before and after laser irradiation. The reflectance spectra of the dorsal skin were measured by a reflectance spectrometer during RMPL. Stasis thermal coagula that clogged the vessel lumen were generated during SMPL irradiation with low incident fluence. However, there was no acute thermal damage of blood vessels. Reflectance spectra measurement showed that the generation of thermal coagula and subsequent thrombus formation increases blood absorption by more than 10% within the first 10 min after laser irradiation. Acute vessel thermal damage could be induced in the target blood vessel by RMPL with low incident fluence of 40 J/cm2. Compared with our previous SMPL study, nearly 30% reduction in incident laser fluence was achieved by RMPL. Low fluence RMPL may be a promising approach to improve the therapeutic outcome for patients with cutaneous vascular lesions by improving energy deposition on the target blood vessel.
关键词： Thermal coagula,1064-nm Nd:YAG laser,Port-wine stain,Repeated multiple pulse laser irradiation,Thrombus formation
更新于2025-09-23 15:19:57
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Tattoo??removal a??the artistic state of the art.a?? Tattoo on forehead, nose, and chin: Successful removal with modified R20 technique using low-fluence Q-switched Nd YAG laser: A case report
摘要： Background: Tattooing is an ancient practice that has been performed all over the world which is used to beautify the skin and augment beauty. Regrettable tattoos are treated with Q switch lasers, in many sessions, and the effectiveness is doubtful. Objectives: The aim of this paper is to demonstrate how a unique protocol of R20 Q switch Nd YAG laser, can be employed successfully in removing long standing facial tattoos, in skin type IV, in an effective disciplined timing and cost wise modalities. The adopted method was a-4 single passes, with 20 minutes gap respectively. Methods and Results: A lady received the conventional Q switch laser at one session, with no noticeable results. On the other session, she received the R20 method, and an immediate whitening reaction was observed. No adverse reactions were noted. Conclusion: The R20 Q technique is very effective tool in a single treatment session than the conventional multiple laser sessions, in tattoo removal, and I would invite other dermatologists utilize it in their clinical setting. This method does not need any newer laser technology, clears the tattoo fast, and cuts down unnecessary treatment duration and cost.
关键词： Q switched Nd YAG laser,R20,laser tattoo removal
更新于2025-09-23 15:19:57
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Investigation on the effect of power and velocity of laser beam welding on the butt weld joint on TRIP steel
摘要： In this study, the characterization of laser weld joint on transformation-induced plasticity (TRIP) steel sheets coupled with Nd:YAG laser welding was investigated, and the influence of welding conditions like angle of weld, power of laser, and welding speed on the strength of the joint was measured. The microstructure, tensile behavior, and microhardness of TRIP laser-welded sheets were examined in detail. The power was maintained constant, i.e., 1800 W, and by relatively varying the velocity from 25 to 30 mm/s, the strength of the joint increased drastically to 11%. In contrast, by varying the power, the effect of velocity was reduced; however, the point performance was enormously stable. Finally, the microhardness behavior of the heat-affected zone and fusion zone was investigated and discussed.
关键词： butt weld joint,heat treatment,TRIP steel,Nd:YAG laser,laser welding
更新于2025-09-23 15:19:57
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Modelling and optimization of process parameters to obtain maximum tensile strength for laser butt welding of 316L austenitic stainless steel sheets
摘要： The attribute of high power density but low energy-input in Laser welding offers exciting solutions to the commonly encountered disadvantages with conventional joining techniques. In this paper, 316L Austenitic Stainless Steel metal sheets were butt welded using Nd:YAG Laser welding system. Owing to its low cost and specific properties such as excellent toughness, higher creep, stress to rupture at elevated temperatures, 316L A.S.S finds wide range of applications in the industrial arena especially in the automobile and marine sectors. Hence, it becomes imperative to examine its post weld properties after performing laser welding and find optimized values of the parameters. The prominent process parameters like Laser Power, Travel speed and Focal length were analysed and optimised. Design of experiment statistical tool was embraced for the systematic conduct of the tests. Response Surface Methodology (RSM) and analysis of variance (ANOVA) techniques were employed to identify the significant process parameters affecting the weld. An empherical relationship involving the parameters was developed to predict the ultimate tensile strength. The 3D response surface plot and contour plots were generated for this model to elucidate the interaction effect of Laser parameters (Travel speed and Focal length), (Laser Power and Focal Length) & (Laser Power and Travel Speed) on Ultimate Tensile Strength. The welded specimens cut by electric discharge machining were prepared for tensile testing as per the ASTM standard. The Universal Testing Machine was used to test the welded specimen. Microhardness Testing was also carried out on the base material and the Heat Affected Zone (HAZ) using Vickers Hardness Testing machine. The tensile tested specimens were used for metallurgical analysis using Scanning Electron Microscope (S.E.M.). Specimen prepared for metallurgical analysis were sectioned, mounted, ground and polished in accordance with recommended procedures in ASTM practice E 3-11. The metallurgical observations showed the existence of undulating topography of ductile fracture surfaces. The investigations reveals that the actual values of the Ultimate tensile strength of the weld were falling close with the predicted strength obtained through the proposed model. It can be concluded that the proposed model in this work can be utilised to predict tensile strength of the weld with more precision.
关键词： Design of Experiments,Ultimate tensile strength,316 L A.S.S,Response Surface Methodology (RSM),Nd:YAG Laser welding
更新于2025-09-23 15:19:57
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Effect of a topical antioxidant serum containing vitamin C, vitamin E, and ferulic acid after Qa??switched 1064a??nm Nd:YAG laser for treatment of environmenta??induced skin pigmentation
摘要： Background: Extrinsic skin aging caused by atmospheric pollutants is associated with a sustained inflammatory response which is a significant risk factor for lentigines and melasma. Aims: The aim of this study was to evaluate the efficacy of topical application of combination formulation of vitamin C, vitamin E, and ferulic acid as an adjuvant to Q-switched Nd:YAG (QSNY) lasers treatment in individuals with lentigines and melasma. Methods: A single blinded, prospective, randomized split-face trial was conducted. Eighteen men and women between 26 and 53 years old were treated with a combination antioxidant serum on one randomized side of their face immediately after QSNY laser and twice daily for 2 weeks. Patients were evaluated using digital photography and spectrometry to assess the melanin index and erythema index. Melasma severity score and global improvement scores also were assessed. Results: The treated side of the face exhibited a significantly greater reduction in the melanin index. There was no significant difference in post-treatment erythema. More clinical improvement was observed on the treated side compared with the untreated side. Conclusions: Our study suggests that topical application of a combination vitamins C, E, and ferulic acid antioxidant formula may be effective as an adjuvant option in QSNY lasers.
关键词： air pollution,lentigo,QS Nd:YAG laser,vitamin C,antioxidant
更新于2025-09-23 15:19:57