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Spherical Mirror and Surface Patterning on Silicon Carbide (SiC) by Material Removal Rate Enhancement Using CO2 Laser Assisted Polishing
摘要： Silicon carbide (SiC) is well known as an excellent material for high performance optical applications because it offers many advantages over other commonly used glasses and metals. The excellent attributes of SiC include high strength, high hardness, low density, high thermal resistance, and low coefficient of thermal expansion. The effect of CO2 laser and its tool path on SiCwere investigated. The process started by creating laser pre-cracks on the desired pattern. Subsequently, laser assisted polishing was conducted on the same tool path. The surface showed a sharp increase in material removal in the areas with laser pre-cracks. This high difference in material removal was used not only to fabricate a ? 1100?mm concave mirror with 127?μm in depth but also to generate macro and micro patterns. Grooves from 2?mm to 200?μm in width and 5?μm to 20?μm depth were successfully generated.
关键词： Material removal rate,CO2 laser,Patterning,Polishing,Hybrid
更新于2025-09-23 15:21:01
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The use of Carboxytherapy alone or in combination with fractional CO2 laser for facial rejuvenation: A splita??face comparative study
摘要： Background A wide variety of minimally invasive treatments are available for skin aging. Recently carbon dioxide therapy (CDT) or carboxytherapy was used in many cosmetic indications including facial rejuvenation. Objective To compare the efficacy of CDT alone versus combined CDT and fractional CO2 laser in management of facial aging. Methods Twenty-Five female patients with bilateral and symmetrical facial aging were included in the study. The right (Rt) hemiface received 8 sessions of CDT whereas the left (Lt) side was treated with combined technique (6 sessions of CDT and 2 sessions of fractional CO2 in between. Clinical and objective evaluation using 3D skin analysis, histological and morphometric analysis were performed. Results Clinical evaluation demonstrated that all patients (100%) were satisfied with no significant difference between both sides of the face (p>0.05). Regarding texture and pigmentation improvement, the Lt side (combined) showed significant improvement compared to the Rt side (p<0.05). Using Antera 3D camera, there was a significant difference (p<0.05) in 3D improvement percent in textural changes while there was no significant difference (p>0.05) in the 3D percent of wrinkles improvement between both sides. The Lt. side showed more significant increase in epidermal thickness after treatment when compared to the Rt. side (p<0.05) with evident neocollagen formation. Conclusion Carboxytherapy is an easy, safe, simple and a relatively effective method for facial rejuvenation with minimal downtime. Better results were achieved when used in combination with fractional CO2 laser.
关键词： skin aging,minimally invasive treatments,fractional CO2 laser,facial rejuvenation,Carboxytherapy
更新于2025-09-23 15:21:01
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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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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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Human Clinical and Histologic Evaluations of Laser-Assisted Periodontal Therapy with a 9.3-??m CO2 Laser System
摘要： This investigation was designed to evaluate the healing response of 9.3-μm CO2 laser–assisted periodontal therapy. Five patients presenting with moderate to severe periodontitis, with an initial pocket depth (PD) ≥ 5 mm and with teeth predetermined to be surgically extracted, were enrolled and consented to treatment with full-mouth CO2 laser–assisted therapy. The laser treatment was carried out in the Ultraguide Mode at a setting of 0.25-mm spot size, with an average power of 0.65 to 1.15 watts and 20% mist. The laser tip was passed from the gingival margin and down apically to the base of the pocket with a sweeping L motion. The teeth were intensely scaled with piezoultrasonic instrumentation afterwards. A second pass of the laser tip was performed for the study teeth. At 9 months, all patients were clinically reevaluated. For sites with an initial pocket depth of ≥ 7 mm, a mean PD reduction of 3.97 ± 1.36 mm and a mean clinical attachment level gain of 3.54 ± 1.54 mm were achieved, resulting in a mean PD of 3.91 ± 0.77 mm. En bloc biopsy samples of four teeth were obtained and analyzed; two demonstrated histologic evidence of new bone formation while the other two healed with a long junctional epithelium with minimal inflammatory infiltrate. Further long-term clinical studies are needed to investigate the treatment stability obtained with a 9.3-μm CO2 laser compared to conventional surgical therapy. Nevertheless, the encouraging clinical results indicated that adjunctive use of the 9.3-μm CO2 laser–assisted periodontal therapy can be beneficial for treatment of periodontally compromised patients.
关键词： histologic evaluation,periodontal therapy,periodontitis,laser-assisted therapy,CO2 laser
更新于2025-09-23 15:19:57
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Comparative Study of Traditional Ablative CO2 Laser-Assisted Topical Antifungal with only Topical Antifungal for Treating Onychomycosis: A Multicenter Study
摘要： Background The predominance of onychomycosis has been increasing recently. New medications and treatment modalities are being researched for better saturation of the antifungal agents through the nail plate topically because of the low resilience of some patients for the oral antifungal agents. Treatment of onychomycosis, mainly moderate to severe, can be very challenging, expensive, and time consuming. Objective The objective of this clinical trial is to compare the efficacy and safety of a manually operated ablative CO2 laser combined with a topical antifungal agent in patients with onychomycosis. Study Design We conducted an open-label controlled prospective study of 160 eligible patients randomized into control and treatment groups with a 1:1 allocation in the department of dermatology in five different hospitals in Shanghai. It was a 6-month study where both groups were treated with a topical antifungal agent, with the treatment group also receiving ablation by the traditional CO2 laser once a month for the first 3 months. Results The clinical efficacy and mycological cure rate were significantly higher (p < 0.001) for the treatment group. Three (3.75%) patients from the control group and 18 (25%) patients from the treatment group achieved complete nail clearance along with negative potassium hydroxide and negative culture (primary endpoint) results at 24 weeks. Mycological clearance with at least moderate nail clearance (secondary endpoint) for the treatment group was also significantly higher (p < 0.001) for the laser treatment group. The laser treatment was mildly painful but tolerable by the patients. No drug interactions for both groups were encountered. Conclusions The ablative CO2 laser is a primitive yet effective modality to be considered for the delivery of topical antifungal agents for the management of mild-to-severe onychomycosis. The laser has good tolerance in patients and is a common equipment found in most dermatology units even those without the latest medical technology.
关键词： onychomycosis,terbinafine,dermatophytes,topical antifungal,CO2 laser
更新于2025-09-23 15:19:57
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Curative effect of cold micro forceps and CO <sub/>2</sub> laser in the treatment of laryngeal amyloidosis
摘要： Background: Amyloidosis is a benign, slowly progressive disease. However, the treatment of laryngeal amyloidosis (LA) has not been studied systematically. Objectives: To investigate the treatment results of cold micro forceps or carbon dioxide laser under microlaryngoscope in the treatment of LA. Methods: A retrospective review was conducted for the cases collected from January 1990 to March 2016 at our department. Results: One hundred and eighteen patients (44 males and 74 females, with an average age of 51.7 years) with LA were identified. The amyloidosis was not found in organs other than the larynges and tracheas. The patients most commonly presented with hoarseness and dyspnea. All patients underwent surgical removal of the amyloid deposits (via micro forceps or CO2 laser). Twenty-nine patients developed recurrences requiring further treatments. The mean interval from treatments to recurrences in these patients was 16.5 months. Five patients were treated more than once. No significant difference was found between cold micro forceps and CO2 laser methods in recurrences. Conclusions: LA generally behaves as a benign disease. Resection of LA either via cold micro forceps or CO2 laser under microlaryngoscope is both safe and effective methods. Regular follow-up with laryngoscopy is indicated for early diagnosis of recurrence.
关键词： Laryngeal amyloidosis,tracheotomy,cold micro forceps,CO2 laser,dyspnea,hoarseness
更新于2025-09-23 15:19:57
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Deep lamellar keratectomy and penetrating scleroplasty using CO <sub/>2</sub> laser photoablation and bimodal grafting for the treatment of a limbal melanoma in a dog
摘要： A novel approach for en bloc resection of a limbal melanoma using a CO2 laser in a dog. Benefits of this advanced technique include excellent surgical precision, improved hemostasis, and the induction of coagulative necrosis of neoplastic cells.
关键词： limbal,canine,melanoma,CO2 laser
更新于2025-09-23 15:19:57
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A novel technique for treating atrophic facial scars in Asians using ultraa??pulse CO <sub/>2</sub> laser
摘要： Background and Aims: Fractional lasers have become increasingly popular for treating atrophic scars, but their effectiveness is limited for deeper scars. We developed a novel technique (manual fractional thermal contraction technology, MFTCT) using an ultra-pulse CO2 laser and evaluated its efficacy and safety for treating atrophic facial scars. Methods: A total of 44 patients with atrophic facial scars were treated with MFTCT every 8 weeks for 1-4 times. Overall scar improvement was assessed by photographs taken at baseline and 3 months after the last treatment according to the 4-point global assessment scale (GAS) and ECCA grading scale. Improvements in color, distortion, and texture were assessed by the modified Manchester Scar Scale and scored individually from 1 to 4. Pain degrees and adverse reactions during and after treatment were recorded. Results: A total of 44 patients completed the treatment and follow-ups; of them, 89% reported at least 50% overall improvement after the last treatment. The mean ECCA scores fell from 67.50 ± 23.98 to 45.68 ± 18.57 (a 32% improvement), and the change was significant (P = .000). The average score for overall improvement was 3.48. The average scores for color, distortion, and texture were 3.07 ± 0.62, 3.27 ± 0.50, and 3.52 ± 0.51, respectively. Mean pain degree score was 4.27 ± 1.04, and mean erythema duration was 28.43 ± 6.58 days. Some patients developed pigmentation for a few months that resolved with topical treatment. Conclusion: Manual fractional thermal contraction technology has definite clinical efficacy in the treatment of atrophic facial scars with fewer adverse reactions and is worth using in the clinical setting.
关键词： thermal contraction,atrophic scars,manual fractional technology,ultra-pulse CO2 laser
更新于2025-09-23 15:19:57
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The laser power effect on the performance of gas leak detector based on laser photo-acoustic spectroscopy
摘要： The use of a homemade gas leak detector based on laser photo-acoustic spectroscopy for fast and sensitive trace gas detection is reported. To obtain optimal acoustic resonator dimensions, resonant frequency variations in terms of resonator's length and radius were simulated, and then a gas leak detector based on photo-acoustic theory was designed and fabricated. The system limit of detection to trace NO2, SO2 and SF6 was 92, 270 and 8 ppb respectively. Therefore, this system can be used as a sensitive gas sensor for detecting partial leakage of some environmental and industrial pollutants. Variations of the resonant frequency versus various concentrations of NO2, SO2 and SF6 in the presence different buffer gases were studied, and results showed that the lighter buffer gas gives a higher resonance frequency. Also, variations of the photo-acoustic signal and SNR of these gas samples in terms of various CO2 laser power at the presence different buffer gases were investigated, and the saturation laser power for each experiment was obtained. Finally, it was shown that experimental results are in good agreement with photo-acoustic theory.
关键词： Photo-acoustic signal,CO2 laser power,gas leak detector,resonant frequency,Infrared spectroscopy
更新于2025-09-23 15:19:57