Background
Keratosis pilaris is a common keratinization disorder of the extensor surfaces of the proximal extremities. Various treatment modalities reduce symptoms, but their efficacy is limited.
...Aims
The aim of this study is to compare the efficiency of Q‐Switched Nd: YAG laser and fractional Er: YAG laser.
Material/Method
The lesions in both arms were randomly divided into areas A and B. Fractional Er: YAG 2940 nm laser performed to area A 1.5 J/cm2, spot size 7 mm, frequency 3 Hz and three passes and Q‐Switched Nd: YAG 1064 nm laser performed to Area B, 4–6 J/cm2 spot size 4 mm, 8 Hz frequency, and as a single pass. Both lasers were performed in 4 sessions at 3‐week intervals. The global improvement scale evaluated treatment responses in dyspigmentation and skin texture.
Results
Twenty patients completed the study, and the mean age of a total of 20 patients was 22.9. There was no significant difference in dyspigmentation and skin texture with global improvement scale between Area A and Area B, respectively (p = 0.078, p = 0.638). In addition, there was no significant difference between patient satisfaction levels after treatment in Area A and Area B (p = 0.868).
Conclusion
The efficiency of the fractional Er: YAG 2940 nm laser was found equal to the Q‐switched Nd: YAG 1064 nm laser. Fractional Er: YAG 2940 nm laser may be a new treatment option in the treatment of keratosis pilaris.
Excessive ultraviolet B ray (UVB) exposure to sunlight results in skin photoageing. Our previous research showed that a Q‐switched 1064 nm Nd: YAG laser can alleviate skin barrier damage through ...miR‐24‐3p. However, the role of autophagy in the laser treatment of skin photoageing is still unclear. This study aims to investigate whether autophagy is involved in the mechanism of Q‐switched 1064 nm Nd: YAG in the treatment of skin ageing. In vitro, primary human dermal fibroblast (HDF) cells were irradiated with different doses of UVB to establish a cell model of skin photoageing. In vivo, SKH‐1 hairless mice were irradiated with UVB to establish a skin photoageing mouse model and irradiated with laser. The oxidative stress and autophagy levels were detected by western blot, immunofluorescence and flow cytometer. String was used to predict the interaction protein of TGF‐β1, and CO‐IP and GST‐pull down were used to detect the binding relationship between TGFβ1 and ITGB1. In vitro, UVB irradiation reduced HDF cell viability, arrested cell cycle, induced cell senescence and oxidative stress compared with the control group. Laser treatment reversed cell viability, senescence and oxidative stress induced by UVB irradiation and activated autophagy. Autophagy agonists or inhibitors can enhance or attenuate the changes induced by laser treatment, respectively. In vivo, UVB irradiation caused hyperkeratosis, dermis destruction, collagen fibres reduction, increased cellular senescence and activation of oxidative stress in hairless mice. Laser treatment thinned the stratum corneum of skin tissue, increased collagen synthesis and autophagy in the dermis, and decreased the level of oxidative stress. Autophagy agonist rapamycin and autophagy inhibitor 3‐methyladenine (3‐MA) can enhance or attenuate the effects of laser treatment on the skin, respectively. Also, we identified a direct interaction between TGFB1 and ITGB1 and participated in laser irradiation‐activated autophagy, thereby inhibiting UVB‐mediated oxidative stress further reducing skin ageing. Q‐switched 1064 nm Nd: YAG laser treatment inhibited UVB‐induced oxidative stress and restored skin photoageing by activating autophagy, and TGFβ1 and ITGB1 directly incorporated and participated in this process.
•Experimental studies based on Nd-YAG LBC have been reviewed.•Four different ways of LBC and different aspects of LBC have been discussed.•Process behaviour with conventional and unconventional sheet ...materials is explained.•Parametric influences on laser cutting performance index have been discussed.•Applications of experimental modeling and optimization approaches during LBC process have been analyzed.
Cutting of sheet material is considered as an important process due to its relevance among products of everyday life such asaircrafts, ships, cars, furniture etc. Among various sheet cutting processes (ASCPs), laser beam cutting is one of the most capable ASCP to create complex geometries with stringent design requirements in difficult-to-cut sheet materials. Based on the recent research work in the area of sheet cutting, it is found that the Nd-YAG laser is used for cutting of sheet material in general and reflective sheet material in particular. This paper reviews the experimental analysis of Nd-YAG laser cutting process, carried out to study the influence of laser cutting parameters on the process performance index. The significance of experimental modeling and different optimization approaches employed by various researchers has also been discussed in this study.
A large amount of Li‐containing ceramic breeder pebbles is packed in the solid breeding blanket of a nuclear fusion reactor. Several pebble fabrication technologies have been proposed in previous ...studies, including wet process, emulsion method, extrusion spheronization, additive manufacturing, and melt process. However, a simple, energy‐effective, and scalable fabrication technology remains to be developed for the automated mass production and reprocessing of used radioactive pebbles post‐operation. Selective laser melting potentially enables the quick and automated fabrication of breeder pebbles. Herein, we employ a high‐power density pulse laser to produce ceramic breeder pebbles. A pulsed YAG laser was irradiated over a lithium metatitanate (Li2TiO3) powder bed in air, and the corresponding temperature was monitored using fiber‐type infrared pyrometers. Spherical Li2TiO3 pebbles were successfully fabricated in a single step with an average diameter of 0.78 ± 0.13 μm and the sintering density of 87.4% ± 5.6% (input power: 7.9 J/pulse). The irradiated Li2TiO3 powder melted and turned spherical under surface tension and rapidly solidified, resulting in uniaxial fine grains and a decrease in the degree of long‐range cation ordering.
One‐step fabrication of Li2TiO3 pebble using pulsed YAG laser
Background: Melasma is a common dermatosis in both men and women showing varying degrees of success with treatment. Relapse of pigmentation in melasma after treatment is a common problem in dark skin ...types that necessitates treatment with novel alternative modalities with better efficacy. Aim: To compare the effectiveness of intradermal platelet-rich plasma vs. 1064 nm Qs Nd-YAG in patients of melasma in a split face comparative study conducted in a Dermatology center over a period of 6 months. Methods: A comparative split face prospective study of 20 female patients of Fitzpatrick skin type IV-V with mixed resistant type of melasma and bilateral involvement of the face were enrolled for the study. Platelet-rich plasma (PRP) was injected intradermally at 2 weeks interval for seven sittings in one half of the face and Qs Nd-YAG was done every week for 12 weeks on the other half of the face. The results were assessed clinically by Hemi-modified MASI score at the end of every 2 weeks. Patients were counselled to continue strict sun protection measures. Patient satisfaction was noted at baseline, 4 weeks, 8 weeks, and 12 weeks. Patients were followed up for 3 months to see for any relapse of the pigmentation and the follow-up results were compared for both modalities of treatment. Results: Comparison of Hemi-mMASI score in both groups showed statistically significant improvement of pigmentation on completion (i.e., at the end of 12 weeks) and not in successive follow-up results every 2 weeks. The subjective assessment was made by PGAIS (Physician global aesthetic improvement scale). Patient satisfaction levels (assessed by SGAIS-Subject global aesthetic improvement scale) also showed significant improvement in successive weeks of treatment in both the groups. Few patients had mild redness and burning post procedure which resolved spontaneously after few hours. Patients were followed up for 3 months to see for reappearance of melasma. The split side treated with PRP showed less reappearance of pigmentation than the side treated with Qs Nd-YAG laser. Conclusion: From this study we concluded that PRP shows a significant improvement in pigmentation in mixed resistant melasma in 12 weeks of treatment with less chances of relapse after 3 months of treatment as compared with Qs Nd-YAG laser. PRP may be used as a first-line treatment in mixed, resistant melasma cases and also as an excellent maintenance therapy in these cases. Limitations: Desired sample size could not be achieved and a longer follow-up period of 6 months could not be materialized.
Background
Fractional CO2 laser and Nd‐YAG laser have been reported to have promising results in the management of keloids. So far, there have been no comparative studies between these laser ...modalities.
Aims
The study aimed to compare the efficacy of fractional CO2, Nd‐YAG, and a combination of both in the management of keloids.
Patients and methods
Forty‐five keloid patients were divided into 3 equal groups: the first received fractional CO2 only, the second received Nd‐YAG only, and the third received a combination of both lasers. Each group received its designated treatment every 4 weeks for 4 sessions. The improvement was evaluated by the “Patient and Observer Scar Assessment Scale” (POSAS). Detection of procollagen I mRNA by RT‐PCR analysis was done.
Results
The assessment by POSAS showed the most significant clinical improvement in the combination group and a less significant improvement in the fractional CO2 group, while the least improvement was seen in the Nd‐YAG group. Molecular assessment via procollagen I yielded matching results.
Conclusion
The study showed that the combination of fractional CO2 and Nd‐YAG lasers has a synergistic effect being the most effective in the management of keloids, fractional CO2 being more effective than ND‐YAG and Nd‐YAG being the least effective.
Macular amyloidosis (MA) is one of the most common types of primary localized cutaneous amyloidosis (PLCA), distributed predominantly over the trunk and extremities. Due to the vast therapeutic ...options, this study aims to compare the effectiveness of Q-switched Nd: YAG laser 1064 nm and Er: YAG laser 2940 nm in treating MA. This clinical trial was performed in 2020–2021 on 33 women with MA. In each patient, the lesion was randomly divided into two areas, A and B. Area A underwent four treatment sessions with 4-week intervals of Q-switched Nd: YAG laser 1064 nm. Area B underwent four treatment sessions with an Er: YAG laser 2940 nm at 4-week intervals. Degree of basal pigmentation and degree of pigmentation after treatment, pruritus intensity, before and after the treatment, and patient and physicians’ satisfaction were measured and compared. The pruritus in patients improved significantly after the study (
P
< 0.001), but no significant differences could be observed between the two groups regarding the improvements (
P
> 0.05). We also found no significant differences between the two groups of patients regarding patient and physicians’ satisfaction rates (
P
> 0.05). The use of both Q-switched Nd: YAG laser and Er: YAG laser resulted in improvements in terms of pruritus, patient and physicians’ satisfaction, and total improvement in pigmentation of the lesions.
The paper investigates the characteristics of sensitization processes of Nd3+ emission in YAG ceramics under broad band pumping by co-doping with Cr3+ and the prospect of using Nd3+ and Cr3+ for ...sensitization of emission of Yb3+. It is evidenced that the energy transfer from Cr3+ to Nd3+ involves both direct and weak migration-assisted processes and is thus dependent on the concentrations of both species. It is also found that the ion–ion interaction responsible for the direct transfer contains besides the dipole–dipole coupling strong superexchange contribution that dominates the transfer to the Nd3+ ions up to the third coordination sphere and has major implication in sensitization. Investigation of (Cr, Nd, Yb)-doped YAG ceramics shows that Cr3+ can sensitize the emission of Yb3+ both via the chain Cr–Nd–Yb or by direct Cr–Yb energy transfer. The prospect of utilization of these processes in the solar-pumped laser is discussed.
•The efficiency of sensitization increases at high Cr and Nd doping concentrations.•The Cr-to-Nd energy transfer involves both direct and migration-assisted processes.•The direct transfer implies both dipole–dipole and superexchange interactions.•The superexchange interaction has major influence on sensitization.•Sensitized emission of Yb3+ in (Cr,Nd,Yb):YAG by Cr–Nd–Yb and Cr–Yb transfers.
•Titanium and its alloys are destroyed by the conventional welding process.•Control of welding parameters and heat input can prevent destruction of Ti alloys.•Pulsed laser welding is precise and ...enables rapid processing with less heat input.•However, rapid cooling rates increase the cracking risk of pulsed laser welding.•Carefully selected laser welding parameters and filler material can prevent cracks.
The excellent properties of titanium and titanium alloys, including corrosion resistance, high strength to weight ratio and high operating temperature, have led to their successful application in various fields. However, titanium and its alloys are destroyed by the conventional welding process if welding parameters are not controlled. Laser welding is one of the most reliable methods for use with titanium alloys because of its precision and rapid processing capability. In addition, it enables control of the welding parameters and their effects. In this study, Ti-6Al-4V alloy sheets were welded by Nd: YAG pulsed laser and the potential crack risk on the weld joints was investigated. The optimum results obtained in 3.9kW peak power, better ductility was obtained from the Grade 1 titanium alloy filling material.
