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Efficacy of fractional carbon dioxide laser therapy for burn scars: a meta-analysis
摘要： Background: The present study evaluates the effectiveness of fractional carbon dioxide (CO2) laser for the treatment of burn scars. Method: Literature search was conducted in electronic databases and studies were selected by following pre-determined eligibility criteria. Random effect meta-analyses were performed to achieve the effect size of the changes (mean difference (MD) between post-treatment and pretreatment values) in selected scar assessment scale scores and other important outcome measures. Results: 14 studies were included. Treatment of burn scars with fractional CO2 laser significantly improved Vancouver Scar Scale (MD (cid:1)3.01 [95% confidence interval (CI) (cid:1)3.79, (cid:1)2.22]; p ? .00001), Patient and Observer Scar Assessment Scale (POSAS)– Patient (MD (cid:1)14.38 [95% CI (cid:1)17.62, (cid:1)11.13]; p ? .00001, POSAS – Observer (MD (cid:1)8.81 [9% CI (cid:1)11.60, (cid:1)6.02]; p ? .00001 and Scar Assessment Scale (MD 1.64 [95% CI 0.49, 2.78]; p ? .005) scores especially with regards to pigmentation, vascularity, pliability, and height of scar. Pain and pruritis also improved with this treatment. Scar thickness measured with ultrasonography decreased non-significantly (MD (cid:1)0.48 [95% CI (cid:1)1.04, 0.09]; p ? .1) whereas cutometer measures, R0 (scar firmness) and R2 (scar elasticity) did not change meaningfully. Conclusion: Fractional CO2 laser therapy is a valuable tool for the treatment of burn scars which has potential for reducing scar severity.
关键词： keloidal,hypertrophic,Burn scars,fractional carbon dioxide laser
更新于2025-09-12 10:27:22
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Utility of High Intensity Laser Therapy Combined with Photobiomodulation Therapy for Socket Preservation After Tooth Extraction
摘要： Objective: High intensity laser therapy (HILT) combined with photobiomodulation therapy (PBMT) using a diode or CO2 laser was administered after extraction of the left ?rst molar in rats. Effects on socket preservation (preservation of the alveolar bone and healing time after extraction) were evaluated histopathologically. Background: Irradiation using a diode or CO2 laser has been shown to hasten wound healing, but the effects remain controversial. Methods: Five-week-old male Wistar rats that underwent extraction of the left maxillary ?rst molar were divided into three groups: diode laser irradiation (diode group), CO2 laser irradiation (CO2 group), and no laser irradiation (control group). HILT (27 J) was performed immediately after tooth extraction to enhance blood coagulation, followed by PBMT (0.7 J) 1 day later to enhance healing. Tissues, including the extraction socket, were removed en bloc 3, 5, 7, 10, and 21 days postextraction to determine the morphological characteristics of wound healing and the distribution of myo?broblasts involved in scar formation. Results: In the diode and CO2 groups, new bone formation and cancellous bone maturation were observed at an early stage of wound healing. The number of myo?broblasts was signi?cantly lower in the laser treatment groups than the control ( p < 0.001), and both treatment groups had a signi?cantly higher alveolar crest height ( p < 0.01), with almost no concavity in the mucosa of the extraction wound. Conclusions: Combined HILT and PBMT following tooth extraction hastened wound healing and preserved alveolar crest height, suggesting a role in socket preservation.
关键词： myo?broblast,carbon dioxide laser,diode laser,socket preservation,tooth extraction,scar tissue,enhanced healing process
更新于2025-09-12 10:27:22
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Treatment of Congenital Melanocytic Nevi in the Eyelid and Periorbital Region With Ablative Lasers
摘要： Background: Congenital melanocytic nevi (CMN) that occur on the eyelid and periorbital region cause cosmetic disfiguring. Laser treatment has aroused interest as an alternative treatment method, and resurfacing lasers have shown promising results. Objective: This study aimed to evaluate the efficacy and safety of carbon dioxide laser and erbium:yttrium aluminum garnet laser to treat CMN of the eyelid and periorbital region. Methods and Materials: Twenty patients with CMN were included in this study and were treated with either the CO2 or erbium:yttrium aluminum garnet laser. Clinical efficacy outcomes were evaluated by visual assessment and L*a*b* color space evaluation at least 6 months after treatment. Results: The average (SD) visual evaluation improvement, assessed on a 5-point scale, was 2.8 (1.27). The mean (SD) values of the relative L* improvement rate and blanching rate of the CMN lesion were 32.0% (47.9%) and 34.1% (36.2%), respectively. Spearman rank correlation coefficient between the objective and subjective evaluations was significant (P < 0.001). Three cases developed partial hypopigmentation. No patient developed hypertrophic scars. Conclusion: The outcomes after laser treatment were variable, although half of the patients achieved greater than 50% clearance. It provides an alternative to surgical excision for the removal of CMN in the difficult regions. Surgery excision is inevitable for some patients.
关键词： carbon dioxide laser,eyelid and periorbital region,congenital melanocytic nevi,ablative laser,Erbium:YAG laser
更新于2025-09-12 10:27:22
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Fields of application for laser beam polishing of optical glasses
摘要： Conventional manufacturing of freeform optics is expensive and elaborate. The laser beam as a polishing tool offers the possibility to produce optical surfaces fast and effective. The aim of new research on laser beam polishing of optical glasses is to achieve a polished surface finish irrespective of the surface geometrics. The carbon dioxide laser is applied to process pre-machined specimen with different roughness’s. During the polishing process an infrared camera is necessary to monitor the temperature on the surface. An annealing process reduces the process-related tensions. In addition, the cleaning process is investigated to minimize the surface damages. To characterize the surface topographic a white-light interferometer and a stylus instrument are applied. Laser beam polishing of minerals glasses such as N-BK7?, BF33? and fused silica enables surface roughness of less than Ra < 5 nm by form maintenance. By means of self-design setup, the adaption of laser beam polishing on glass cylinders, lenses or freeform is possible. As a result a parallel laser beam with a diameter of 12.65 mm is applied to process tilted surfaces up to 45°. With a laser parameter modulation, the angle-dependent absorption depending on the intensity of the laser radiation is considered.
关键词： white-light interferometer,surface finish,optical glasses,annealing process,cleaning process,infrared camera,carbon dioxide laser,laser beam polishing,stylus instrument
更新于2025-09-11 14:15:04
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Infrared photodissociation spectroscopic and theoretical study of [Co(CO <sub/>2</sub> ) <sub/><i>n</i> </sub> ] <sup>+</sup> clusters
摘要： The mass-selected infrared photodissociation (IRPD) spectroscopy was utilized to investigate the interactions of cationic cobalt with carbon dioxide molecules. Quantum chemical calculations were performed on the [Co(CO2)n]+ clusters to identify the structures of the low-lying isomers and to assign the observed spectral features. All the [Co(CO2)n]+ (n=2?6) clusters studied here show resonances near the CO2 asymmetric stretch of free CO2 molecule. Experimental and calculated results indicate that the CO2 molecules are weakly bound to the Co+ cations in an end-on configuration via a charge-quadrupole electrostatic interaction. The present IRPD spectra of [Co(CO2)n]+ clusters have been compared to those of Ar-tagged species ([Co(CO2)n]+-Ar), which would provide insights into the tagging effect of rare gas on the weakly-bounded clusters.
关键词： Structure,Cationic cobalt,Quantum chemical calculation,Infrared photodissociation spectroscopy,Carbon dioxide
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) - Gas Detection using a MEMS-Based Swept Laser Source
摘要： Swept Laser Sources (SLS) provide wide wavelength tuning range and high tuning speed making them attractive sources for sensing, biomedical and industrial imaging applications. MEMS based swept lasers have recently gained more attention with their potential low cost, high tuning speeds, high output power and possibility of integration with other devices. The adaptation of MEMS based swept lasers in gas sensing would allow the detection of multiple gases at high speed and sensitivity with a single device which is a major benefit over many of the available commercial devices. In this work, we present practical sensing of carbon dioxide gas using a MEMS based swept laser. The SLS under study consists of a ring fiber cavity of length 20 m, a semiconductor optical amplifier (SOA) as a gain medium, an isolator to allow a uni-directional laser operation, a fiber polarization controller, an intracavity in-plane MEMS optical tunable filter and a tapping fiber-coupler to couple some power out of the loop. The MEMS filter is a Fabry-Perot filter, based on deeply etched 80-μm height silicon/air Bragg mirrors. One of the mirrors is movable using an electrostatic comb-drive actuator. By applying a voltage across the comb-drive, an attractive force is developed which pulls the movable mirror towards the fixed one, thus the resonant wavelength of the filter is tuned, and the lasing wavelength as well.
关键词： MEMS,swept laser source,carbon dioxide,Fabry-Perot filter,gas detection
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - P-type SiOx front emitters for Si heterojunction solar cells
摘要： We have applied p-type nanocrystalline silicon-oxide (p-SiOx) as front emitter in silicon heterojunction solar cells. The evolution of structural, optical, and electrical properties of p-SiOx as a function of the carbon-dioxide/silane flow rate ratio used in the gas mixture has been investigated, comparing also the film characteristics with those of p-type amorphous and nanocrystalline silicon thin films often used in the cells. Selected p-SiOx films with suitable electrical properties have been inserted in silicon heterojunction solar cells based on n-type FZ c-Si <100> wafers, passivated with ultrathin intrinsic a-Si:H buffers. Improvement of all the photovoltaic parameters has been observed with the emitter with higher oxygen content. The results have been correlated with the increased transparency and enhanced field-effect passivation obtained thanks to the presence of sufficient carbon dioxide in the gas mixture for the p-SiOx layer growth.
关键词： field-effect passivation,silicon heterojunction solar cells,p-type nanocrystalline silicon-oxide,optical and electrical properties,carbon-dioxide/silane flow rate ratio
更新于2025-09-11 14:15:04
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Influence of Light Coupling Configuration and Alignment on the Stability of HWG-Based Gas Sensor System for Real-Time Detection of Exhaled Carbon Dioxide
摘要： A mid-infrared tunable diode laser absorption spectroscopy (TDLAS) gas sensor based on hollow waveguide (HWG) gas cell for real-time exhaled carbon dioxide (eCO2) detection is reported. A 2.73 μm distributed feedback (DFB) laser was used to target a strong CO2 absorption line, and wavelength modulation spectroscopy (WMS) with the second harmonic (WMS-2 f ) was used to retrieve the CO2 concentration with high sensitivity. The influence of different parameters, including coupling configuration of HWG, laser-to-HWG and HWG-to-detector coupling alignment on the stability of the HWG sensor is systematically studied. The HWG eCO2 sensor showed a fast response time of 2.7s, detection limit of 17 ppmv, and measurement precision of 20.9 ppmv with a 0.54 s temporal resolution. The eCO2 concentrations changed in breath cycles were measured in real time. The Allan variance indicated that the detection limit can reach 1.7 ppmv, corresponding to a detection sensitivity of 1.3×10?8 cm?1 Hz?1/2, as the integration time increases to 26 s. This work demonstrates the performance characteristics and merits of HWG eCO2 sensor for exhaled breath analysis and potential detection for other exhaled gases.
关键词： hollow waveguide,distributed feedback laser,carbon dioxide,Tunable diode laser absorption spectroscopy
更新于2025-09-11 14:15:04
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Carbon Dioxide Precipitation Method to Prepare Zinc Oxide
摘要： Carbon dioxide (CO2) was firstly used to precipitate Zn ions with urea to prepare zinc oxide (ZnO). The advantages of this method were small particle size, high yield and low sensitivity to conditions, such as temperature and time, and the decrease of solvent consumption. Further, the influence of carbon dioxide pressure, reaction time and temperature were studied and optimized.
关键词： Particle Size,Nanoparticles,Solvent Effects,Carbon Dioxide Utilization,Precipitation Method
更新于2025-09-10 09:29:36
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Water Vapour and Methane Coupling in the Stratosphere observed with SCIAMACHY Solar Occultation Measurements
摘要： An improved stratospheric water vapour dataset has been derived from SCIAMACHY/ENVISAT solar occultation measurements. It is based on the same algorithm which has already been successfully applied to methane and carbon dioxide retrievals, thus resulting in a consistent dataset for these three constituents covering the altitudes 17–45 km, the latitude range between about 50 and 70?N, and the time interval August 2002 to April 2012. The new water vapour data agree with collocated results from ACE-FTS and MLS/Aura within about 5%. A significant positive water vapour trend for the time 2003–2011 is observed at lower stratospheric altitudes of about 0.015 ppmv year?1 around 17 km. Between 30 and 37 km the trend becomes significantly negative (about -0.01 ppmv year?1). The combined analysis of the SCIAMACHY methane and water vapour time series reveals that stratospheric methane and water vapour are strongly correlated and show a clear temporal variation related to the Quasi-Biannual-Oscillation (QBO). Above about 20 km most of the water vapour seems to be produced by methane, but short-term fluctuations and a temporal variation on a scale of 5–6 years are observed. At lower altitudes the balance between water vapour and methane is affected by stratospheric transport of water vapour and methane from the tropics to higher latitudes via the shallow branch of the Brewer-Dobson circulation and by the increasing methane input into the stratosphere due to the rise of tropospheric methane after 2007.
关键词： stratospheric water vapour,Quasi-Biannual-Oscillation,solar occultation,Brewer-Dobson circulation,methane,SCIAMACHY,carbon dioxide
更新于2025-09-09 09:28:46