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Laser printing of micro-electronic communication systems for smart implants applications
摘要： Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium alloy for implant’s fabrication. In this sense, this work presents a promising approach to print communication systems by using laser technology, aiming integrate the smart components on titanium implants. Laser has been employed as a versatile tool to modify the surface in different ways, such as texturing, oxidizing and sintering. Silver wires have been printed on Ti6Al4V surface in order to conduct electrical current. To minimize current loss for the substrate, titanium oxide layer has been produced by different methods (laser and anodization). Laser sintering (LS) has been also compared to a conventional method (Hot-pressing- HP) to consolidate the silver powder into the cavities. In comparison to the conventional techniques, laser demonstrated to be a competitive approach to oxidizing the surface and also for consolidating the micro-wires on Ti6Al4V surface. Consequently, the micro-wires printed by laser approach presented satisfactory results in terms of electrical resistance, actuating as the conductor path for electrical current, with values of 0.0131 Ω, which is similar to the resistance of the wire printed in an insulator substrate.
关键词： Ti6Al4V titanium alloy,Laser oxidation,Implants,Laser surface modification,Nd:YAG laser,Laser sintering
更新于2025-09-23 15:21:01
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Experimental and clinical study of simultaneous dual-wavelength laser action in energetic cataract surgery
摘要： A new technique of energy cataract surgery with the simultaneous use of two wave-length of laser emission acting as high-intensity laser—endodissector (Nd:YAG, wave-length λ = 1.44? μm) and a low-intensity laser—endobiostimulator (He–Ne, wavelength λ = 0.632? μm) is represented. The surgical technique is bimanual. The radiation of high-intensity laser ensures the destruction of cataract lens of any density level without addi-tional assistance of ultrasound and without manual fragmentation. The laser tip, which contacts the eye tissues, does not heat up. In the process of high-intensity laser action split-ting and spalling of the eye lens core occurs. Laser energy does not go beyond the lens capsule as it is almost completely absorbed by the liquid of the anterior chamber (water) at less than 1?mm from the distal end of the laser tip. Simultaneous exposure to radiation of high-intensity and low-intensity lasers delivered to the eye lens via one laser tip provide to prevent the progression of posttraumatic inflammatory process in the eye at the initial stage of the start of pathophysiological intracellular changes. This ensures high efficiency and safety of simultaneous dual-wavelength laser cataract extraction (DW LCE).
关键词： 0.632?μm He–Ne laser,Phacoemulsification,1.44?μm Nd:YAG laser,Dual-wavelength laser cataract extraction,Intraoperative endoocular bio-stimulation
更新于2025-09-23 15:21:01
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Disinfection of Contaminated Metal Implants with an Er:YAG Laser
摘要： Infections related to orthopedic procedures are considered particularly severe when implantation materials are used, because effective treatments for biofilm removal are lacking. In this study, the relatively new approach for infection control by using an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser was tested. This laser vaporizes all water containing cells in a very effective, precise, and predictable manner and results in only minimal thermal damage. For preliminary testing, 42 steel plates and 42 pins were seeded with mixed cultures. First, the minimally necessary laser energy for biofilm removal was determined. Subsequently, the effectiveness of biofilm removal with the Er:YAG laser and the cleansing of the metal implants with octenidine‐soaked gauze was compared. Then, we compared the effectiveness of biofilm removal on 207 steel pins from 41 patients directly after explantation. Sonication and scanning electron microscopy were used for analysis. Laser fluences exceeding 2.8 J/cm2 caused a complete extinction of all living cells by a single‐laser impulse. Cleansing with octenidine‐soaked gauze and irradiation with the Er:YAG laser are both thoroughly effective when applied to seeded pins. In contrast, when explanted pins with fully developed biofilms were analyzed, we found a significant advantage of the laser procedure. The Er:YAG laser offers a secure, complete, and nontoxic eradication of all kinds of pathogens from metal implants without damaging the implant and without the possible development of resistance. The precise noncontact removal of adjacent tissue is a decisive advantage over conventional disinfectants. Therefore, laser irradiation could become a valuable method in every debridement, antibiotics, and implant retention procedure.
关键词： implant‐related infection,DAIR,Er:YAG laser,laser disinfection,pin‐tract infection,biofilm removal
更新于2025-09-23 15:21:01
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Effect of Pulse Energy, Pulse Frequency, and Tip Diameter on Intracanal Vaporized Bubble Kinetics and Apical Pressure During Laser-Activated Irrigation Using Er:YAG Laser
摘要： Objective: Er:YAG laser-activated irrigation (LAI) is an effective method of root canal cleaning, but irrigant extrusion from the apical foramen has been a concern. We aimed to analyze the effects of pulse energy, pulse frequency, and laser tip diameter on intracanal vapor bubble kinetics and periapical pressure generation during LAI with Er:YAG laser. Background: Irrigant vapor bubble kinetics are one of indices of root canal cleaning ef?cacy. However, few studies have compared laser pulse conditions to vapor bubble kinetics, in relation to periapical pressure. Methods: A plastic root canal model (apical diameter 0.50 mm, 6% taper, 20 mm long) was ?lled with distilled water, and LAI with Er:YAG laser (Erwin AdvErl Unit; 30, 50, or 70 mJ; 10, or 20 pulses per second; laser tip R200T or R600T) was performed with the end of the tip ?xed at 15 mm from the root apex. The number, maximum diameter, and velocity of vapor bubbles were analyzed by high-speed video imaging. Pressure generated outside the apical foramen was measured with a pressure sensor. Results: Vapor bubble count and maximum diameter increased signi?cantly with pulse energy, pulse frequency, and tip diameter. Vapor bubble velocity increased signi?cantly with pulse frequency, but not with pulse energy or tip diameter. Periapical pressure increased signi?cantly with pulse energy, pulse frequency, and tip diameter. Conclusions: The pulse frequency was the single factor that signi?cantly affected all the examined parameters (the number, diameter, and velocity) of vapor bubble kinetics together with the periapical pressure.
关键词： Er:YAG laser,vapor bubble maximum diameter,vapor bubble velocity,laser-activated irrigation,vapor bubble count
更新于2025-09-23 15:21:01
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Effect of Laser Beam Conditioning on Fabrication of Micro-Channels in Al <sub/>2</sub> O <sub/>3</sub> Bio-ceramics Using Nd:YAG Laser
摘要： In the present study, laser micro-milling tests were carried out to fabricate micro-channels on Alumina bio-ceramics (Al2O3), using a Q-Switched 30W Nd:YAG pulsed laser. A systematic approach based on a full factorial Design of Experiment (DoE) has been successfully applied with the aim to detect which and how the key input laser process parameters affect the channel dimensional accuracy. The examined process parameters were the laser beam scanning speed, the pulse frequency and the pulse intensity. Optical microscope was used to analyze the channel geometries responses (i.e. channel's top width, bottom width, depth, and taper wall angle). Moreover, mathematical models for predicting the micro-channel geometries are successfully proposed for controlled micro-milling of micro-channels in Al2O3. Results reveal that, the change of scanning speed and laser intensity significantly affected the ablated channel’s geometries. Further it is observed that the channel depth and width increase linearly with increasing of laser intensity and decreasing of scanning speed and not much affected by changing of pulse frequency. Finally, the experimental results bear a good agreement with the proposed prediction models.
关键词： micro-channels,Nd:YAG laser,Al2O3 bio-ceramics,Design of Experiment,Laser micro-milling
更新于2025-09-23 15:21:01
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Efficacy of microneedling versus fractional Er:YAG laser in facial rejuvenation
摘要： Background: Microneedling and fractional lasers have been used in facial rejuvenation with acceptable results and low adverse effects. Aims: To compare the efficacy of microneedling with fractional Er:YAG in facial skin rejuvenation. Patients/Methods: This study was planned as a split-face clinical trial. Volunteers were randomly allocated to receive three monthly treatments on each side of the face, one with fractional Er:YAG laser and one with microneedling. The assessments included investigating clinical outcomes by two blinded dermatologists accompanied by measuring skin biophysical characteristics including cutaneous resonance running time (CRRT) and transepidermal water loss (TEWL). Moreover, possible adverse effects, downtime, and patients' satisfaction were recorded at baseline, 1 month after each treatment, and 3 months after the last treatment session. The protocol was approved by the Iranian Registry of Clinical Trials (IRCT20160820029436N3). Results: Of the 32 selected volunteers, 24 subjects completed the study. The clinical assessment showed a significant improvement of the face appearance along with a significant reduction in dyschromia, and periorbital wrinkling (P-value < .05), with both procedures without any considerable difference between two methods. Moreover, the patients showed substantial satisfaction with both modalities with no statistically significant difference. Mean TEWL and CRRT values also decreased significantly in both groups with no considerable difference. The downtime was significantly shorter in the microneedling-treated side. There were no long-lasting or severe adverse effects after treatment with both methods. Conclusion: Microneedling and fractional Er:YAG laser have comparable efficacy in facial rejuvenation, but little downtime of the former makes it preferable for many patients.
关键词： facial rejuvenation,fractional Er:YAG laser,wrinkle,microneedling
更新于2025-09-23 15:21:01
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High-peak-power and narrow-linewidth Q-switched Ho:YAG laser in-band pumped at 1931 nm
摘要： We describe a high-peak-power, narrow-linewidth Q-switched Ho:YAG laser at 2097 nm wing-pumped by a high power and high brightness Tm:fiber source at 1931.5 nm. The laser was wavelength locked and spectrum narrowed utilizing a volume Bragg grating as the input coupler, resulting a linewidth (FWHM) of less than 0.1 nm. At 22.7 W of incident pump power, stable pulses of 5.5 mJ pulse energy and 17.5 ns of pulse duration have been generated at repetition frequency of 1 kHz, corresponding to peak power of 314.3 kW.
关键词： narrow-linewidth,Q-switched Ho:YAG laser,volume Bragg grating,1931.5 nm,high-peak-power
更新于2025-09-23 15:21:01
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Novel report on structural, optical and electrical investigation into brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate single crystal: a promising material for high-power laser, ultrahigh cooling, sensor and detector applications
摘要： A new brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate (B4M3NB0.5H) NLO single crystal was harvested from saturated solution by solvent evaporation method. Crystal system and symmetric type of B4M3NB0.5H compound were analyzed by structure analysis. Linear optical parameters of title compound were discussed in detail by UV–visible analysis. Lifetime values of the molecule were quanti?ed by ?uorescence study, and it con?rms the good crystalline perfection of the grown crystal. The SHG ef?ciency is 5.11 times superior to the KDP material. By utilizing Nd:YAG laser as an input, SLDT measurement of the crystal was done. The grown crystal has good crystalline nature which is analyzed by HRXRD study. Dielectric behavior of B4M3NB0.5H crystal was discussed in detail. With the help of theoretical approach, few of the solid-state parameters were calculated and listed. Piezoelectric charge coef?cient and piezovoltage were calculated to be 4.5 p C/N and 0.0417 p V m/N, respectively. The TGA and DTA spectrum con?rms that the title compound is thermally stable up to 101 °C.
关键词： piezoelectric charge coefficient,brucinium 4-methyl-3-nitrobenzoate,fluorescence study,solvent evaporation method,SHG efficiency,HRXRD study,NLO single crystal,Nd:YAG laser,dielectric behavior,UV–visible analysis,TGA and DTA spectrum
更新于2025-09-23 15:21:01
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Transurethral en bloc resection of non-muscle invasive bladder cancer with holmium:YAG laser in pediatric patients: cases series and review of literatures
摘要： Introduction Urothelial bladder carcinoma frequently occurs in adults over 60?years of age; yet it affects only 0.1–0.4% of patients before the first 2?decades of life. We present two cases of transitional cell carcinoma in two young patients treated with holmium:YAG laser to demonstrate the effectiveness of this technique in pediatrics. Cases and methods Case study 1 During a routine abdomen ultrasound, a 14-year-old female showed a endoluminal formation about 10 × 6 × 10?mm of size, in the left paramedian site. There was an absence of meaningful vascular signs during color-Doppler. Physical examination and laboratory exams were all normal. Case study 2 A 12-year-old female presented with acute macroscopic haematuria. No other symptoms were associated. Bladder ultrasound revealed an irregular 15?mm intravesical endophytic lesion in the posterior-superior area. In both cases, treatment commenced with an en bloc enucleation. For the resections, a 272?μm holmium:YAG fiber laser was used through the 12 Ch cystoscopy working channel with an energy of 0.8–1?J/pulse and a frequency of 8–10?Hz. Results There was no haematuria after the procedure and the transurethral catheter remained for 12?h. The histological diagnosis was papillary urothelial neoplasm of low malignant potential. Cystoscopy was performed 3 and 9?months after the surgery and an ultrasound every 6?months, which all came back normal. The follow-up continued for each patient with a cystoscopy once a year, according to EAU guidelines. Conclusion Based on the findings, holmium:YAG laser is a good alternative to treat superficial transitional cell carcinoma in pediatric patients.
关键词： Transurethral en bloc resection,Transitional cell carcinoma,PUNLMP,Holmium:YAG laser,Pediatric bladder cancer
更新于2025-09-23 15:21:01
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An experimental study on joining of AISI 304 SS to Cu by Nd-YAG laser welding process
摘要： In this current study, a challenging dissimilar metal combination AISI 304 stainless steel and copper is welded by pulsed wave Nd-YAG laser welding process without use of any filler material, followed by its mechanical as well as metallurgical investigation. Macroscopic as well as microscopic examination of the weld surface and weld bead has been carried out to observe the weld penetration depth and metallurgical behavior inside the weld zone. Weld pool geometry confirms about attainment of full penetration depth in pulsed wave Nd-YAG laser and also describes that the penetration depth is directly proportional pulse energy as (penetration depth7 J = 69%) < (penetration depth14 J = 82%) < (penetration depth21 J = 100%). The formed copper micro-channels suggest that the copper solidifies last and flows inside the weld zone matrix during the solidification. The average width of the heat affected zone (HAZ) and partially melting zone (PMZ) have been found to be 23.0 mm and 6.0 mm on the stainless steel (SS) side respectively. The microhardness (MH) study shows that (MHCopper = 75 HV0.1) < (MHWeld zone = 90–200 HV0.1) < (MHSS = 210 HV0.1).
关键词： PMZ,Copper micro-channels,HAZ,Dissimilar metal,Nd-YAG laser
更新于2025-09-23 15:21:01