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Transcription-coupled nucleotide excision repair is coordinated by ubiquitin and SUMO in response to ultraviolet irradiation
摘要： Cockayne Syndrome (CS) is a severe neurodegenerative and premature aging autosomal-recessive disease, caused by inherited defects in the CSA and CSB genes, leading to defects in transcription-coupled nucleotide excision repair (TC-NER) and consequently hypersensitivity to ultraviolet (UV) irradiation. TC-NER is initiated by lesion-stalled RNA polymerase II, which stabilizes the interaction with the SNF2/SWI2 ATPase CSB to facilitate recruitment of the CSA E3 Cullin ubiquitin ligase complex. However, the precise biochemical connections between CSA and CSB are unknown. The small ubiquitin-like modifier SUMO is important in the DNA damage response. We found that CSB, among an extensive set of other target proteins, is the most dynamically SUMOylated substrate in response to UV irradiation. Inhibiting SUMOylation reduced the accumulation of CSB at local sites of UV irradiation and reduced recovery of RNA synthesis. Interestingly, CSA is required for the efficient clearance of SUMOylated CSB. However, subsequent proteomic analysis of CSA-dependent ubiquitinated substrates revealed that CSA does not ubiquitinate CSB in a UV-dependent manner. Surprisingly, we found that CSA is required for the ubiquitination of the largest subunit of RNA polymerase II, RPB1. Combined, our results indicate that the CSA, CSB, RNA polymerase II triad is coordinated by ubiquitin and SUMO in response to UV irradiation. Furthermore, our work provides a resource of SUMO targets regulated in response to UV or ionizing radiation.
关键词： SUMOylation,DNA damage response,transcription-coupled nucleotide excision repair,Cockayne Syndrome,UV irradiation,ubiquitination
更新于2025-09-12 10:27:22
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A powerful tool for comparing different test procedures to measure the probability and density of laser induced damage on optical materials
摘要： The determination of the laser damage resistance of optics in the nanosecond regime is based on statistical tests and approaches because the response of the components is mainly related to the presence of defects randomly distributed in the optics and is therefore probabilistic in nature. For practical reasons, the tests are mostly carried out with beams of small dimensions (several tens of micrometer), that make it possible to determine a damage probability from which a laser damage threshold is extracted. This threshold is, however, highly correlated with the size of the test beam and the sampling of the test procedure. Some measurements are also made with beams of large dimensions (several millimeters) from which a damage density is determined. However, the relationship between the damage probability and the damage density is not trivial. It is based on assumptions that are difficult to verify because the experimental validations are carried out on different laser installations. In order to study accurately the coherence between these tests with small and large beams, as well as the link between damage probability and damage density, it is necessary to perform measurements on the same laser installation. We propose here, to compare for the first time, the results obtained with the same laser source with a large beam and also with small beams. The small beams are shaped from phase objects specifically implemented to obtain several small beams from a single larger beam. The consistency of the laser damage that results from both sets of measurements is demonstrated here. It validates the assumptions made and the specific mathematical treatment implemented to establish the link between the two approaches. In fine, it also validates and strengthens the approach previously developed from the rasterscan procedure [Lamaignère et al., Rev. Sci. Instrum. 78, 103105 (2007)] used to measure damage densities from the scanning of optics with beams of small dimensions. The reported original work based on phase objects thus makes it possible to replicate small beam tests with a large beam facility. The comparison between the results from the small beams and the results from the large beam experiments definitively makes the link between damage probabilities and damage densities. This also shows that small beam tests are reasonable representative of tests carried out with large beams.
关键词： rasterscan procedure,optics,nanosecond regime,phase objects,statistical tests,laser damage resistance,damage density,damage probability
更新于2025-09-11 14:15:04
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Effects of laser-assisted grinding on surface integrity of zirconia ceramic
摘要： Zirconia ceramics has an important position in the field of biomaterials because of excellent mechanical properties. Because of abrasive resistance and hardness, conventional machining of zirconia ceramic is difficult and time-consuming. A nontraditional hybrid laser-assisted grinding (LAG) system combining laser and cubic boron nitride (CBN) grinding wheel was developed for machining zirconia ceramic. This hybrid system utilizes the outstanding thermostability of zirconia ceramic: The material present on the cutting path is rapidly removed by local laser heating and grinding wheel. A combined theoretical and experimental study was performed to evaluate different modes of machining of zirconia ceramic. The machining parameters were predicted by numerical analysis. The surface quality, surface morphology, and subsurface damage of zirconia ceramic specimens were analyzed and compared. The results show that LAG can easily achieve ductile regime grinding in the same machine tool. Compared with conventional grinding, the surface integrity of zirconia ceramic was significantly improved by the LAG process. LAG could achieve ductile regime grinding with a large depth-of-cut. It changes the machinability of zirconia ceramic.
关键词： Surface quality,Surface morphology,Laser-assisted grinding,Zirconia ceramic,Subsurface damage
更新于2025-09-11 14:15:04
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Analytical estimations of temperature in a living tissue generated by laser irradiation using experimental data
摘要： This paper presents an analytical approach associated with Laplace transformation, experimental temperature data, and a sequential concept over time to obtain the thermal damage and the temperature in a living tissue due to laser irradiation. The analytical solutions in the Laplace domain are appreciably obtainable. The thermal damage to the tissue is completely assessed by the denatured protein range using the formulation of Arrhenius. Numerical outcomes for temperatures and the thermal damages are graphically introduced. Besides, the comparison between the numerical computations and the existing experimental study shows that a current mathematical model is an e?ective tool for evaluating the biological heat transfer in biological tissues.
关键词： Living tissue,Thermal damage,Bioheat transfer,Laplace transform
更新于2025-09-11 14:15:04
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Iatrogenic Damage to the Periodontium Caused by Laser: An Overview
摘要： Lasers have been used in dentistry since 1994 to treat a number of dental problems. A variety of lasers are now available for use in dentistry. Once stated as an intricate technology with restricted usage in clinical dentistry, there is a growing awareness of the usefulness of lasers in the armamentarium of the modern dental practice, where they can be used as an adjunct or alternative to various long-standing approaches.
关键词： Electrosurgery,modern dentistry,iatrogenic damage,laser,types of laser
更新于2025-09-11 14:15:04
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Thermal/Mechanical Interaction in Laser Perforation Process: Numerical-Model Buildup and Parametric Study
摘要： In this paper, a generic thermal/mechanical interaction model was developed to predict the penetration rate and mechanical damage around perforation tunnels that resulted from the laser perforation of rock samples. The perforating process is driven by heat emitted by a laser beam directed at the surface of a sample. The temperature propagation, thermal expansion, and thermal/mechanical interaction were modeled by coupling heat conduction in solid media with the elastic/plastic constitutive mechanical response of rocks. The phase changes that occur during the melting and evaporating process were accounted for in the latent heat of fusion and of vaporization. The heating boundary was updated dynamically along with the evolution of perforation channels. The model was used to parametrically investigate the effects of material properties, stress ratio, and laser-beam characteristics on the penetration rate and mechanical damage.
关键词： mechanical damage,numerical model,laser perforation,rock samples,thermal/mechanical interaction,penetration rate
更新于2025-09-11 14:15:04
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Modelling of Optical Damage in Nanorippled ZnO Produced by Ion Irradiation
摘要： Here, we report on the production of nanoripples on the surface of ZnO bulk substrates by ion beam erosion with 20 keV Ar+ ions at an oblique incidence (60°). The ripple patterns, analyzed by atomic force microscopy, follow a power law dependence for both the roughness and the wavelength. At high fluences these ripples show coarsening and asymmetric shapes, which become independent of the beam direction and evidence additional mechanisms for the pattern development. The shallow damaged layer is not fully amorphized by this process, as confirmed by medium energy ion scattering. A detailed study of the damage-induced changes on the optical properties was carried out by means of spectroscopic ellipsometry. Using a 3-layer model based on Tauc-Lorenz and critical point parameter band oscillators, the optical constants of the damaged layer were determined. The results showed a progressive reduction in the refractive index and enhanced absorption below the bandgap with the fluence.
关键词： ripples,ZnO,patterning,sputtering,damage,spectroscopic ellipsometry
更新于2025-09-11 14:15:04
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Infrared Low-Level Laser Therapy (Photobiomodulation Therapy) before Intense Progressive Running Test of High-Level Soccer Players: Effects on Functional, Muscle Damage, Inflammatory, and Oxidative Stress Markers—A Randomized Controlled Trial
摘要： The effects of preexercise photobiomodulation therapy (PBMT) to enhance performance, accelerate recovery, and attenuate exercise-induced oxidative stress were still not fully investigated, especially in high-level athletes. The aim of this study was to evaluate the effects of PBMT (using infrared low-level laser therapy) applied before a progressive running test on functional aspects, muscle damage, and inflammatory and oxidative stress markers in high-level soccer players. A randomized, triple-blind, placebo-controlled crossover trial was performed. Twenty-two high-level male soccer players from the same team were recruited and treated with active PBMT and placebo. The order of interventions was randomized. Immediately after the application of active PBMT or placebo, the volunteers performed a standardized high-intensity progressive running test (ergospirometry test) until exhaustion. We analyzed rates of oxygen uptake (VO2 max), time until exhaustion, and aerobic and anaerobic threshold during the intense progressive running test. Creatine kinase (CK) and lactate dehydrogenase (LDH) activities, levels of interleukin-1β (IL-1-β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), levels of thiobarbituric acid (TBARS) and carbonylated proteins, and catalase (CAT) and superoxide dismutase (SOD) activities were measured before and five minutes after the end of the test. PBMT increased the VO2 max (both relative and absolute values—p < 0:0467 and p < 0:0013, respectively), time until exhaustion (p < 0:0043), time (p < 0:0007) and volume (p < 0:0355) in which anaerobic threshold happened, and volume in which aerobic threshold happened (p < 0:0068). Moreover, PBMT decreased CK (p < 0:0001) and LDH (p < 0:0001) activities. Regarding the cytokines, PBMT decreased only IL-6 (p < 0:0001). Finally, PBMT decreased TBARS (p < 0:0001) and carbonylated protein levels (p < 0:01) and increased SOD (p < 0:0001)and CAT (p < 0:0001) activities. The findings of this study demonstrate that preexercise PBMT acts on different functional aspects and biochemical markers. Moreover, preexercise PBMT seems to play an important antioxidant effect, decreasing exercise-induced oxidative stress and consequently enhancing athletic performance and improving postexercise recovery. This trial is registered with Clinicaltrials.gov NCT03803956.
关键词： PBMT,inflammatory markers,oxidative stress,Photobiomodulation therapy,infrared low-level laser therapy,exercise performance,muscle damage,soccer players
更新于2025-09-11 14:15:04
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Low-Damage Reactive Ion Etching of Nanoplasmonic Waveguides with Ultrathin Noble Metal Films
摘要： Nanoplasmonic waveguides utilizing surface plasmon polaritons (SPPs) propagation have been investigated for more than 15 years and are now well understood. Many researchers make their efforts to find the best ways of using light and overcoming the speed limit of integrated circuits by means of SPPs. Here, we introduce the simulation results and fabrication technology of dielectric-metal-dielectric long-range nanoplasmonic waveguides, which consists of a multilayer stack based on ultrathin noble metals in between alumina thin films. Various waveguide topologies are simulated to optimize all the geometric and multilayer stack parameters. We demonstrate the calculated propagation length of Lprop = 0.27 mm at the 785 nm wavelength for the Al2O3/Ag/Al2O3 waveguides. In addition, we numerically show the possibility to eliminate signal cross-talks (less than 0.01%) between two crossed waveguides. One of the key technology issues of such waveguides’ nanofabrication is a dry, low-damage-etching of a multilayer stack with extremely sensitive ultrathin metals. In this paper, we propose the fabrication process flow, which provides both dry etching of Al2O3/Au(Ag)/Al2O3 waveguides nanostructures with high aspect ratios and non-damage ultrathin metal films patterning. We believe that the proposed design and fabrication process flow provides new opportunities in next-generation photonic interconnects, plasmonic nanocircuitry, quantum optics and biosensors.
关键词： plasmonic nanocircuitry,multilayer waveguide,nanoplasmonic waveguide,low-damage alumina etch,noble metals etching,multilayer stack etching
更新于2025-09-11 14:15:04
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Reflections on the Er:YAG Laser Used in “Nonthermal Mode” to Rejuvenate Skin
摘要： CO2 and Er:YAG lasers are both actively used for laser skin rejuvenation, both ablative and microablative. Despite seeming similarities in efficiency of their radiation’s absorption by soft tissues, these lasers may have completely different effects on skin: tissue vaporization with CO2 laser radiation always assumes existence of areas with irreversible thermal effects such as coagulation, dehydration, carbonization, and vaporization. If Er:YAG and vaporization is used for the same purpose, same thermal damage areas may be obtained but smaller in size. However, in case of sufficiently high energy density and short duration of pulses, an ablation mode may be implemented, in the case in which areas of irreversible thermal changes are contained within vaporization zone. Thus, underlying layers of irradiated tissue are not thermally damaged.
关键词： ablation mode,cavitation,Er:YAG laser,microablation,CO2 laser,skin rejuvenation,thermal damage
更新于2025-09-11 14:15:04