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The influence of morphological distribution of melanin on parameter selection in laser thermotherapy for vascular skin diseases
摘要： Port wine stains (PWSs) are congenital vascular malformations that progressively darken and thicken with age. Currently, laser therapy is the most effective way in clinical management of PWS. It is known that skin pigmentation (melanin content) affects the radiant exposure that can be safely applied to treat PWS. However, the effect of melanin distribution in the epidermis on the maximum safe radiant exposure has not been studied previously. In this study, 10 different morphological distributions of melanin were proposed according to the formation and migration characteristics of melanin, and the two-scale heat transfer model was employed to investigate the influence of melanin distribution on the threshold radiant exposure of epidermis and blood vessels. The results show that melanin distributions do have a strong effect on laser parameter selection. When uniform melanin distribution is assumed, the threshold radiant exposure to damage a typical PWS blood vessel (50 μm diameter) is 8.62 J/cm2 lower than that to injure epidermis. The optimal pulse duration is 1–5 ms for a typical PWS blood vessel of 50 μm when melanin distribution is taken into consideration. PWS blood vessels covered by non-uniformly distributed melanin are more likely to have poor response to laser treatment.
关键词： Port wine stains,Melanin distribution,Two-scale model,Cryogen spray cooling,Laser treatment
更新于2025-09-12 10:27:22
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Efficacy of 577‐nm Pro‐Yellow laser in port wine stain treatment
摘要： A port-wine stain (PWS) is a congenital capillary malformation that is seen in 0.3–0.5% of newborns. Although many types of lasers have been used to treat PWSs, few studies have investigated the efficacy of 577-nm Pro-Yellow lasers. The aim of this study was to establish the efficacy of Pro-Yellow lasers in PWS treatment. In total, 26 patients, comprising 15 females (57.7%) and 11 males (42.3%) with a mean age of 24.7 ± 11.8 (range 1–50) years were included in the study. All were treated with a 577-nm Pro-Yellow laser at 4-week intervals, 3–10 times. The sessions initially used scan mode and a fluence dose of 24 J/cm2 per session, on average. The mean dose was increased by 4 J/cm each session and the maximum dose administered was 44 J/cm2. A mean regression of 68.8 ± 13.9% in the size of the lesions over 5.23 ± 2.7 sessions was observed. There was no statistically significant difference between the female and male patients when they were compared in terms of the number of treatment sessions (p = .789) and treatment success (p = .39). These case series demonstrate that the Pro-Yellow laser is a safe and well-tolerated treatment for PWSs. However, deep-seated lesions required more treatment sessions and it was observed that clinically the lesions did not completely disappear.
关键词： Pro Yellow laser,577 nm laser,laser treatment,port-wine stain
更新于2025-09-11 14:15:04
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Advances in Contact Angle, Wettability and Adhesion || Laser Surface Engineering of Polymeric Materials for Enhanced Mesenchymal Stem Cell Adhesion and Growth
摘要： Owing to them being relatively inexpensive and easy to manipulate, polymers are becoming more widely used within the biomedical industry for several different applications. As an example, because of its high wear resistance, low moisture absorption and high chemical resistance, poly(ether ether ketone) is commonly used as a biomaterial in the healthcare and biomedical industries. However, poly(ether ether ketone) surface properties are not optimum for efficient or enhanced bio-functionality, leading it to have somewhat inferior wettability and adhesion characteristics. On account of this, many researchers are now looking to employ surface engineering techniques to improve and enhance the surface properties of poly(ether ether ketone), enhancing its biomimetic nature and improving the bio-adhesion properties. This chapter discusses the importance of Mesenchymal Stem Cells (MSCs), the biological applications of poly(ether ether ketone) and the application of lasers for surface engineering of poly(ether ether ketone) for modifying mesenchymal stem cell response. Through the application of CO2 laser surface engineering it has been shown that laser surface engineering can have a positive effect on the rate of human mesenchymal cell growth, highlighting the opportunities for the healthcare and biomedical industries to adopt such technique. In addition, discussion of including poly(ether ether ketone) and other polymer materials as bio-composite materials for future research is introduced for enhancing material properties.
关键词： surface modification,surface engineering,poly(ether ether ketone),Mesenchymal stem cells,polymeric biomaterials,bio-engineering,laser treatment
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Laser Engineered Surface Structures for Custom Design of Secondary Electron Yield
摘要： Secondary Electron Yield (SEY) occurs in a system when a primary electron impinges a material’s surface and induces the emission of a 1st and potentially 2nd generation secondary electrons. The total number of secondary electrons per primary electron is the SEY. This phenomenon forms a highly challenging problem in many systems, for example in particle accelerators, where significant levels of SEY form as an electron cloud and can perturbate the circulating beams and generate a high level of heat load to be absorbed by cooling and cryogenics. The Large Hadron Collider (LHC) has a 54-km beam pipe in which copper-laminated steel beam-screens are placed in order to shield the beam pipes from heat loads, but inherently result in unwanted SEY. As such, the development of methods which mitigate the SEY are increasingly appealing, including surface texturing, shaping the geometry and orientation of patterns etched into the surfaces, and carbon-coating of the interior of the beam pipes in the Super Proton Synchrotron (SPS). Previously we have shown that nanosecond pulsed laser treatment of copper surfaces at 532 nm could significantly increase the optical absorbance of the surface, and furthermore reduce the SEY to close to 1. More recently we demonstrated that surface structures produced by a picosecond pulsed laser at 532nm exhibited SEY values below 1 and were successfully tested in a dipole magnet in the Super Proton Synchrotron (SPS) accelerator at CERN.
关键词： laser treatment,Secondary Electron Yield,copper surfaces,SEY,particle accelerators
更新于2025-09-11 14:15:04
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Experimental Study of Laser Texturing Processes on the Lubricant Retention of Carbide (WC-Co) Surfaces
摘要： Machining processes usually involve relevant wear effects on the cutting tool, producing undesirable surface features on the work-pieces. Lubricants and cooling fluids are used with the aim to minimize the wear phenomena as well as high temperatures produced during the cutting process. However, the use of these type of fluids may have an adverse environmental impact. For this reason, the reduction of quantity of cutting fluids used in the machining process is a requirement to improve the performance and sustainability of the process. For this purpose, this work proposes the increase of the lubricant retention ability for cutting tools based on surface modification. In this research, micro-geometrical features of Carbide (WC-Co) surfaces have been modified by laser texturing techniques. A wide range of roughness topographies were developed by changing the laser irradiation parameters of energy density of pulse (Ed) and scanning speed of the beam (Vs). Different geometries of the textured tracks (single spots, linear tracks, circular tracks) also were studied. Moreover, through specific roughness features conducted by texturing process, the retention ability for cutting fluids was modified. This feature was evaluated by the contact angle between liquid and solid phases. Performed modification allowed to increase the self-lubricant effect of the WC-Co surface. Proposed methodology has been validated on carbide tools under lubricated machining processes. Wear effects on the cutting tool were reduced and the surface finish of the machined parts was remained at least in the same ranges as non-modified tools.
关键词： surface modification,cutting tool texturing,lubricant retention,laser treatment,carbide
更新于2025-09-11 14:15:04
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Criteria of pressure and thermal damage during laser irradiation of port wine stains: Which is dominant to vascular lesions?
摘要： Port wine stains (PWSs) are congenital dermal vessel proliferations mainly treated with laser therapy. The complete removal of the vessel lesions is rarely achieved because of a lack of discriminatory analysis of the two competitive laser damages to blood vessels, namely, pressure damage and thermal damage. Unlike complete vessel constriction, which is caused by thermal damage that can be measured by temperature-related integral X, vessel rupture results from pressure damage, which has been seldom studied. In this study, the rupture potential index based on wall pressure (RPIP) was calculated as the ratio of locally acting pressure to the pressure threshold. RPIP > 1 and X > 103 were adopted as benchmarks to judge pressure damage (vessel rupture) and thermal damage (complete vessel constriction), respectively. A computational fluid dynamics simulation was carried out to provide the temperature and pressure field in the PWS vessel model during irradiation by 595 nm pulsed dye laser (PDL) or 1064 nm Nd:YAG laser. Numerical results showed that for the 595 nm laser, vessels constantly underwent rupture. The area of high RPIP determined the degree of rupture by predicting the large and multiple rupture locations of the vessel. By contrast, for the 1064 nm laser, complete constriction was the main damage type. To a single vessel of 100 lm diameter, the optimized laser parameters were E = 10 J/cm2 with tp = 6 ms for 595 nm PDL and E = 180 J/cm2 with tp = 6 ms 1064 nm for Nd:YAG laser.
关键词： Port wine stains,Vessel rupture,Vessel constriction,Computational fluid dynamics,Laser treatment
更新于2025-09-11 14:15:04
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Long-term outcomes of laser treatment for congenital melanocytic nevi
摘要： Background: Although various laser treatments have been tried for congenital melanocytic nevi (CMNs), only small retrospective studies with short-term follow-up had been done to assess outcomes. Objective: We analyzed the long-term outcomes of laser treatment for CMN and compared these outcomes with those of a combination treatment including partial excision and lasers. Methods: Patients with CMN treated with lasers were retrospectively reviewed, and patients with [3 years of follow-up were grouped as the long-term follow-up group. Results: A total of 67 cases of CMN were reviewed. Among 20 patients (20/52, 38.5%) with near total clearance during laser-only treatment, 11 patients were in the long-term follow-up group, and 5 of 11 showed repigmentation. In total, 15 patients showed repigmentation regardless of clearance, and the mean period until repigmentation was 3.93 years from the initial treatment. Patients with partial excision and laser combination treatment showed higher Investigator’s Global Assessment scores, fewer laser treatments, and shorter treatment periods compared with patients with laser-only treatment. Limitations: This is a retrospective study, and various laser devices were used. Conclusion: More than 4 years of follow-up is required to evaluate the efficacy of lasers in CMN, and partial excision and laser combination treatment might be an effective treatment option.
关键词： repigmentation,partial excision,laser treatment,congenital melanocytic nevi
更新于2025-09-11 14:15:04
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Selective surface treatment by means of IR-laser – a new approach to enhance the rate capability of cathodes electrodes for Li-ion batteries
摘要： To meet today's demands on lithium-ion batteries for battery electrical vehicles in terms of energy density, electrodes with a high active mass loading as well as a low porosity are strived for. However, such high energy electrodes exhibit a poor rate capability, mainly due to limited lithium-ion diffusion. In this work, we present a laser-based surface treatment of calendered cathodes to partially overcome this conflict of objectives. NCM-based electrodes with different porosities were superficially modified by using IR-laser radiation with pulse duration in the nanosecond-regime. By detailed microscopic analysis, we show that it is possible to selectively ablate the binder/additive-compound without impairing the active material particles. Thus, it is possible to open surface pores which were closed during calendering by the binder/additive-compound. As a result, laser treated highly densified cathodes show a significantly improved rate capability at C-rates > 2C compared to untreated reference samples. The most significant improvement of > 20 % of the rate capability is found at 5C for electrodes with lowest porosity of 20 %. The experimental findings suggest that an enhanced electrolyte access to the active mass and thus, a reduced lithium-ion transport resistance lead to the improved electrochemical characteristics. In addition to the short-term rate capability tests, preliminary investigations of the cyclic stability of electrodes modified in such a way were performed. The state-of-health after one hundred 1C charge/discharge-cycles was about 95 % for both, the laser treated and the pristine electrodes.
关键词： surface modification,NCM cathode,Li-ion batteries,laser treatment,rate capability
更新于2025-09-11 14:15:04