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Mathematical modeling of heat distribution on carbon fiber Poly(ether-ether-ketone) (PEEK) composite during laser ablation
摘要： Since large amounts of energy are transferred precisely to the material in a very short time, laser and material parameters strongly affect the laser process quality. Mathematical modeling of heat distribution during cavity formation on carbon fiber reinforced PEEK composite material was performed. The temperature distribution equation has been obtained by the Fourier method. At the first stage, 1 J energy laser beam was sent onto the material and the cavity on the composite material was obtained. The constants in the temperature distribution equation obtained by making measurements over the cavity were found. Then the cavities were created with 2, 3 and 4 J laser beams to prove its reliability of the model. The results obtained from the measurement on the cavities and calculated from the temperature distribution equation were compared. Since the unidirectional carbon fibers were used, the obtained cavities have an elliptical shape. Verification experiments were carried out using two different heat conduction constants for in direction along fibers and perpendicular to carbon fibers. Experimental results and the mathematical model are in good agreement.
关键词： Mathematical modeling,Fourier method,Laser ablation,Fiber reinforced composites,Poly(ether-ether-ketone) (PEEK)
更新于2025-09-23 15:21:01
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Stereotactic laser anterior corpus callosotomy for Lennoxa??Gastaut syndrome
摘要： Objective: Corpus callosotomy is an effective palliative treatment for drug-resistant Lennox-Gastaut syndrome (LGS). Laser interstitial thermal therapy has been increasingly used in the treatment of epilepsy. Here, we assess the safety and effectiveness of minimally invasive stereotactic laser anterior corpus callosotomy (SLACC) for drop attacks in LGS. Methods: We reviewed sequential cases of patients with medically intractable LGS who underwent SLACC using a two-cannula technique between November 2014 and July 2019. Pre- and postoperative magnetic resonance imaging was used to measure the anteroposterior length of callosal ablation (contrast-enhancing lesion) and estimated disconnection (gap in tract projections on diffusion tensor imaging). Patients were followed longitudinally to assess clinical outcomes. Results: Ten patients were included in this study. The median age was 33 (range = 11-52) years, median duration of epilepsy was 26 (range = 10-49) years, and median duration of postoperative follow-up was 19 (range = 6-40) months. In the anteroposterior direction, 53 ± 7% (mean ± SD) of the corpus callosum was ablated and 62 ± 19% of the corpus callosum was estimated to be disconnected. Six (60%) of 10 patients achieved >80% seizure reduction, two (20%) of whom became seizure-free. Eight (80%) patients had >80% reduction in drop attacks, five (50%) of whom became free of drop attacks. Three patients subsequently underwent laser posterior callosotomy with further improvement in drop attacks and/or overall seizure frequency. One patient had an asymptomatic intracerebral hemorrhage along the cannula tract. One patient developed significant aggression after becoming seizure-free. Significance: Seizure outcomes following SLACC were comparable to previously reported outcomes of open callosotomy, with reasonable safety profile. SLACC appears to be an effective alternative to open anterior corpus callosotomy with minimal postoperative discomfort and a short recovery period.
关键词： Lennox-Gastaut syndrome,corpus callosotomy,laser ablation,drop attacks,vagus nerve stimulation
更新于2025-09-23 15:21:01
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Nanosecond laser ablation assisted the enhancement of antibacterial activity of copper oxide nano particles embedded though Polyethylene Oxide/Polyvinyl pyrrolidone blend matrix
摘要： Via one-step Laser Ablation process, different contributions of copper oxide nanoparticles (CuONPs) were scattered through Polyethylene Oxide (PEO)/Polyvinyl pyrrolidone (PVP) blend matrix. The obtained films were characterized via XRD and FTIR. Their micro-structural features and morphological behaviors were investigated using TEM and FESEM. The CuONPs were formed in a spherical shapes with dimensions around 50 nm in case of processing time 5.0 min, while their size was deteriorated at t=25.0 min to be around 30 nm upon TEM micrographs. In addition, surface roughness average was enhanced from 26.0 nm at no contribution of CuONPs reaching to 37.0 nm at the highest content. The composite films displayed antibacterial activity against E. coli and S. aureus upon CuONPs contribution. The antibacterial activity jumped from no effect at no-contribution of CuONPs to be around 89– 4 % and 82– 3 % against E. coli and S. aureus respectively at their highest contribution. Therefore, it could be seen that these films were carried out using facile method and displayed a great effectiveness through biological environment which could encourage more investigations for these compositions to be suggested for wound healing applications.
关键词： PVP,laser ablation,Antibacterial,CuONPs,PEO
更新于2025-09-23 15:21:01
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Handbook of Nanoparticles || Laser Fabrication of Nanoparticles
摘要： Lasers are widely used for material processing (cutting, drilling, cleaning, ?lm deposition, etc.). A recent application is for nanoparticle fabrication. Pulsed laser ablation is by far the fastest and clean method to fabricate nanoparticles directly from bulk targets. For this purpose, target ablation is performed in vacuum, in gas atmosphere, or in liquids with fast (nanosecond) and ultrafast (picosecond, femtosecond) laser pulses. Mostly metal but also semiconductor and ceramic nanoparticles were fabricated. In the early stage of this technique, the main problem was the large size distribution of the produced nanoparticles. But the possibility to independently handle laser pulse characteristics (wavelength, power density, pulse duration, etc.) and the accurate control and optimization of the ambient parameters is leading to an ef?cient tailoring of the nanoparticle size, due also to helpful theoretical and numerical models. A review is presented of the most important studies and of the obtained results.
关键词： laser ablation in liquids,ps-laser ablation,oxide nanoparticles,fs-laser ablation,metal nanoparticles,semiconductor nanoparticles,ns-laser ablation
更新于2025-09-23 15:19:57
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Laser ablation at high repetition rate coupled to laser-induced breakdown spectroscopy for analysis of non-matrix matched standards
摘要： Laser ablation at kilohertz repetition rate coupled to laser-induced breakdown spectroscopy (kHz LA-LIBS) was used for the analysis of non-matrix matched metallic standards. Kilohertz LA-LIBS exploited the demonstrated advantages of the analytical technique referred to as laser-ablation laser-induced breakdown spectroscopy (LA-LIBS), while at the same time increased the amount of ablated mass available for analysis. By separating the laser ablation process from the excitation and analysis stages, every configuration of LA-LIBS has demonstrated to produce better analytical results during the analysis of non-matrix matched samples. This research reports the analytical response of five analytes (Al, Cu, Fe, Mg and Mn) from eight standard reference materials. The standards included four aluminum alloys, a high temperature alloy, a cupro-nickel alloy, a stainless steel and a low alloy steel. The analytical performance of kHz LA-LIBS was evaluated through the estimation of the signal-to-noise ratio, relative standard deviation, linearity and y-intercept of calibration curves and limits of detection. Calibration plots relating the analyte concentration to the Fe-normalized (internal standard), peak-to-background and net intensities were constructed. The increased amount of ablated mass in kHz-LA-LIBS rendered superior figures compared with traditional LIBS and other LA-LIBS configurations. The limits of detection of kHz LA-LIBS were improved by 3 to 14 times as compared to those reported previously and were estimated in the range of 0.07 and 0.30% by mass.
关键词： matrix effects,non-matrix matched standards,laser ablation laser-induced breakdown spectroscopy,high repetition laser ablation
更新于2025-09-23 15:19:57
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Development of Method Enhanced Laser Ablation Efficiency According to Fine Curvature of the Polymer through the Preliminary Preparation Process Using UV Picosecond Laser
摘要： In processes using the ultrashort pulsed laser, the phenomenon that the ablation efficiency is reduced due to the increase of the shielding effect of the generated plume is increasingly caused by the use of the high power and high repetition rate. A new method is needed to prevent a decrease in ablation efficiency in processing using an ultrashort pulsed laser. In this study, the proposed a processing method that can improve the ablation efficiency by providing an efficient escape path of plume, and examine the feasibility of a new processing method. The new method we proposed is a method of laser processing after generating a fine curvature in the polymer as a preliminary preparation. The fine curvature of the polymer produced by the preliminary preparation induces an artificial chimney-like opening along the path of the incident beam during laser processing, thereby enabling the plume to be effectively removed. The experiment for examine the feasibility through a new method was conducted using a 10-picosecond laser of UV wavelength with two optical systems. As a new processing method, when processing with ultrashort pulse laser, it was observed that the ablation efficiency improved.
关键词： fine curvature of polymer,picosecond pulse laser,artificial chimney,laser ablation,enhanced laser ablation efficiency
更新于2025-09-23 15:19:57
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Plasma charging effect on the nanoparticles releasing from the cavitation bubble to the solution during nanosecond Pulsed Laser Ablation in Liquid
摘要： The laser induced plasma during the nanosecond Pulsed Laser Ablation in Liquid (PLAL) plays a crucial role in the nanoparticles (NPs) formation and charging. It was demonstrated that during the plasma phase evolution, once the NPs are formed, they are charged with the excess of plasma electrons. Immediately after the plasma phase extinguishes, the NPs will be released in the induced vapor bubble, generated by the fast energy exchanges between the plasma and the liquid. The excess of charge in the NPs preserves them from the agglomeration during the bubble evolution and can induces an electrostatic pressure able to eject the particles outside the cavitation bubble. In this work, the plasma charging effect on the particle releasing in solution, during the bubble evolution, has been investigated. Temporal evolution of laser induced bubble on silver target immersed in water has been measured with the shadowgraph technique. Then, starting from the experimental bubble radius evolution, the releasing of the NPs from the cavitation bubble to the liquid has been modeled by comparing the electrostatic pressure of the charged NPs cloud and the pressure of the cavitation bubble. The following discussion proposes a new insight of the mechanism of NPs releasing in solution.
关键词： Laser Ablation Synthesis in Solution (LASIS),Cavitation bubble,NPs releasing,Pulsed Laser Ablation in Liquid (PLAL),NP formation
更新于2025-09-23 15:19:57
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Feasibility and safety of flush endovenous laser ablation of the great saphenous vein up to the saphenofemoral junction
摘要： Objective: The optimal ablation distance from the catheter tip to the common femoral vein during endovenous laser ablation (EVLA) of the great saphenous vein (GSV) is a matter of debate. In this study, we evaluated the feasibility and safety of ?ush ablation (fEVLA) of the GSV. Methods: This single-center, retrospective analysis of prospectively collected data included all consecutive fEVLA interventions of the GSV between September 2017 and October 2018. Interventions were performed with a 1470-nm radially emitting ?ber. Primary end points were technical feasibility of fEVLA and endovenous heat-induced thrombosis (EHIT) class 2 to class 4. Secondary end points were procedure-related complications; anatomic success at week 6; and ?ush occlusion at day 1, day 10, and week 6. Results: A total of 135 consecutive intended fEVLA procedures were performed in 113 patients (86 female, 27 male). The average body mass index was 24.9 6 4.3 kg/m2. The Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class for these patients was C2 in 78 (57.8%), C3 in 48 (35.6%), C4 in 8 (5.9%), and C5 in 1 (0.7%). The GSV diameter at the saphenofemoral junction was 9.4 6 2.7 mm with a maximum of 16 mm. In 126 cases (93.3%), concomitant treatment of tributaries with phlebectomy or foam sclerotherapy was performed. In 127 cases (94.1%), fEVLA was technically feasible; in 8 cases (5.9%), appropriate catheter tip placement was not possible. In these cases, “standard” GSV ablation 10 to 20 mm distal to the saphenofemoral junction was performed. In the remaining 127 cases, one (0.8%) EHIT class 2 and one (0.8%) EHIT class 3 developed at day 10. After a 2- to 3-week course of anticoagulation with rivaroxaban, these EHIT cases resolved without sequelae. Furthermore, one (0.8%) super?cial vein thrombosis and one (0.8%) calf vein thrombosis at the site of phlebectomy were observed. No local groin complication occurred. Flush occlusion was observed in 94.5%, 95.3%, and 88.2% of the cases at day 1, day 10, and week 6, respectively. Multivariate regression analysis revealed no signi?cant association between ?ush ablation at day 1 and age, body mass index, CEAP class, ?ber type, maximum vein diameter, or applied joules per centimeter. Conclusions: The results of this study suggest that fEVLA of the GSV using a radial emitting laser is feasible and seems to be safe.
关键词： Endovenous crossectomy,Endovenous laser ablation,Varicose veins,Great saphenous vein,Flush endovenous laser ablation
更新于2025-09-23 15:19:57
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Nanoparticle enhanced laser ablation and consequent effects on laser induced plasma optical emission
摘要： In this paper the plasmon enhanced ablation for elemental analysis is investigated with several experiments in order to point out the crucial questions concerning the laser matter interaction under the effect of plasmonic coupling between the nanoparticle (NP) system and the laser ablation pulse. The correlation between the electromagnetic field enhancement and the signal enhancement during NP enhanced laser induced breakdown spectroscopy (NELIBS), as well as the laser matter interaction at the nanoscale, is discussed in the case of noble metal NPs deposited on metal samples. The results suggest that, while laser pulse energy is concentrated in the space between the NPs, the NP system is shielded by the field enhancement distribution after the laser pulse interacts with the plasmons of the NP system. Finally the comparison of the laser energy transfer to the sample between NELIBS and conventional LIBS is discussed.
关键词： LIBS,Nanoparticle enhanced laser induced breakdown spectroscopy (NELIBS),laser ablation,plasmonic enhanced ablation,LA-ICP-MS
更新于2025-09-23 15:19:57
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Laser Ablation versus Radiofrequency Ablation for benign non-functioning thyroid nodules: Six-month results of a randomised, parallel, open-label, trial (LARA trial)
摘要： Background: No direct prospective studies comparing laser ablation (LA) and radiofrequency ablation (RFA) for debulking benign non‐functioning thyroid nodules (BNTNs) exist. We aimed to compare the efficacy and safety of both techniques in patients with solid or predominantly solid BNTN. Methods. This six‐month, single‐use, randomized open label parallel trial compared the following primary endpoints between the RFA and LA groups six months after treatment: (1) nodule volume reduction expressed as a percentage of nodule volume at baseline; (2) proportion of nodules with more than 50 % reduction (successful rate). We enrolled subjects with a solitary BNTN or dominant nodule characterized by pressure symptoms/cosmetic problems or patients without symptoms who experienced a volume increase >20% in one year. Nodules underwent core needle biopsy (CNB) for diagnosis. Patients were randomly assigned (1:1) to receive LA or RFA. Safety was assessed in all randomly assigned participants. Results: Sixty patients were randomly assigned to receive either RFA or LA (1:1) between January 2016 and November 2018. Both groups were similar in basal nodule volume, thyroid function, histology, symptoms/cosmetic score, and procedure time. At six months, the nodule volume reduction was 64.3% (95% confidence interval 57.5 ‐ 71.2%) in the RFA group and 53.2% (47.2 – 95.2%; p = 0.02) in the LA group. This effect was also confirmed in the linear regression model adjusted for age, baseline volume, and proportion of cellular component (LA vs RFA percent change Delta= ‐12?8, p=0?02). No significant difference was observed in success rate 6‐month after treatment (RFA vs LA: 86?7% vs 66?7%, p=0?13) or in thyrotropin level between the groups. Although improved, no significant difference was observed between RFA and LA for compressive symptoms (RFA: 2.13 vs 3.9, p<0?001; LA: 2.4 vs 3.87, p<0?001) and cosmetic score (RFA: 1?65 vs 2?2, p<0?001; LA: 1?85 vs 2?2, p<0?001). The adverse event rates (local pain, dysphonia, thyrotoxicosis, fever, hematoma) were 37% (n=11) and 43% (n=13) for RFA and LA, respectively, with no requirement for hospitalization. Conclusion: While the success rate was similar in the RFA and LA groups, RFA achieved a significantly larger nodule volume reduction at six months.
关键词： Radiofrequency ablation,Laser ablation,Benign non‐functioning thyroid nodules,Thyroid nodules,Volume reduction
更新于2025-09-23 15:19:57