- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Evaluation of soft‐tissue response around laser microgrooved titanium percutaneous devices
摘要： Percutaneous devices are prone to epidermal downgrowth and sinus tract formation, which can serve as a nidus for bacterial colonization and increase the risk of peri-prosthetic infection. A laser microgrooved topography has been shown to limit gingival epidermal downgrowth around dental implants. However, the efficacy of this laser microgrooved topography to limit epidermal downgrowth around nongingival percutaneous devices is yet to be investigated. In this study, devices with a porous-coated subdermal component and a percutaneous post were designed and manufactured. The proximal 2 mm section of the percutaneous post were left smooth, or were textured with either a porous coating, or with the laser microgrooved topography. The smooth and porous topographies served as controls. The devices were tested in a hairless guinea pig back model, where 18 animals were randomly assigned into three groups, with each group receiving one implant type (n = 6/group). Four weeks postimplantation, the devices with surrounding soft-tissues were harvested and processed for histological analyses. Results indicated that the laser microgrooved topography failed to prevent epidermal downgrowth (23 ± 4%) around percutaneous posts in this model. Furthermore, no significant differences (p = 0.70) in epidermal downgrowth were present between the three topographies, with all the groups exhibiting similar measures of downgrowth. Overall, these findings suggest that the laser microgrooved topography may not halt downgrowth around percutaneous devices for dermal applications.
关键词： laser microgrooved topography,percutaneous devices,peri-prosthetic tissue,surface topography,epidermal downgrowth
更新于2025-09-12 10:27:22
-
Femtosecond Laser Implantation of a 355-Degree Intrastromal Corneal Ring Segment in Keratoconus: A Three-Year Follow-Up
摘要： Purpose. To evaluate the outcomes of femtosecond laser-assisted implantation of a 355-degree intracorneal ring (ICR) (Keraring) in patients with keratoconus in the three-year follow-up. Setting. Future Femtolaser Center, Sohag, Egypt. Design. Prospective interventional case series. Patients and Methods. A prospective case series of 38 eyes of 26 patients with keratoconus had implantation of the 355-degree ICR keraring after tunnel creation with a femtosecond laser. The uncorrected visual acuities (UCVA) and best-corrected visual acuities (BCVA), sphere, cylinder, and manifest refraction spherical equivalent (SE), and mean keratometry (K), K max, and K min were evaluated preoperatively and 3, 6, 12, 24, and 36 months postoperatively, and all complications were reported. Results. 38 eyes of 26 patients with mean age 25.92 ± 5.44 years were enrolled in the study, 11 were males (42.3%). The mean UCVA improved from 0.93 ± 0.21 to 0.63 ± 0.21 logMAR (P ≤ 0.001) and the mean BCVA from 0.67 ± 0.22 to 0.43 ± 0.26 logMAR (P < 0.001). The mean sphere, cylinder, and spherical equivalent have been changed dramatically from preoperative to 3 month postoperative, which is statistically signi?cant (P ≤ 0.001), and the changes between 1 and 2 years and 2 and 3 years are also considerable and statistically signi?cant; the K max and K min and K mean improved and the changes were statistically signi?cant (P ≤ 0.001), and the changes between one, two, and three years were also statistically signi?cant. The safety and e?cacy indices were changed through the three-year follow-up. The complications were corneal neovascularization (36.84%), corneal melting (26.3%), and ring extrusion (31.5%) at the end of the study. Conclusions. Implantation of a 355-degree intracorneal keraring using femtosecond laser improved the visual, refractive, and topographic parameters in keratoconus patients, with a high rate of ICR extrusion and instability. The study has been registered for the Pan African Clinical Trial Registry (http://www.pactr.org) database within No: PACTR201810796878908 on 29 October 2018.
关键词： keratoconus,Keraring,refractive error,femtosecond laser,visual acuity,corneal topography,intracorneal ring
更新于2025-09-12 10:27:22
-
Influence of surface topography on fatigue behavior of Ti6Al4V alloy by laser powder bed fusion
摘要： This article deals with the understanding of the influence of surface topography on fatigue behavior of Ti6Al4V alloy specimens produced by laser powder bed fusion (LPBF). The same laser parameters and scan strategy were used for all specimens, giving a sample density higher than 99.5 %. Two different surface topographies were obtained by using the top and side surfaces of the specimens. The surface topography and morphology were investigated by optical surface profilometry and focus variation microscopy. Four-point bending fatigue test was performed on specimens with top and side surfaces as the highest stressed surface respectively. Machined specimens were used as reference. The features of the fracture surface, such as crack initiation and propagation, were analyzed by focus variation and scanning electron microscopy (SEM). Both, fatigue results and fracture surface investigations, were correlated and discussed in relation to surface topography and microstructure, as well as manufacturing parameters.
关键词： laser powder bed fusion,surface topography,Ti6Al4V alloy,fatigue test,fracture mechanisms
更新于2025-09-12 10:27:22
-
Effect of initial surface topography during laser polishing process: Statistical analysis
摘要： Surface finish is one of the most important quality characteristics of fabricated components. Laser polishing (LP) is one of the advanced manufacturing surface finishing techniques that has been recently developed and successfully employed for improving surface quality without deteriorating the overall structural form through surface smoothing by melting and redistributing a thin layer of molten material. This paper advances the statistical analysis of the LP process emphasizing aspects of the effect of the initial surface topography. Flat and ground initial surfaces are used for comparative statistical analysis of initial and polished profiles obtained experimentally. Their profile geometries and surface quality characteristics, such as, roughness, were compared and analyzed. In addition, LP process was experimentally investigated as a thermodynamic operator represented by a transfer function and it was examined by means of a coherence function.
关键词： statistical analysis,initial topography,Laser polishing,travel speed,laser power,surface quality,roughness
更新于2025-09-12 10:27:22
-
Topography-guided transepithelial phototherapeutic keratectomy to treat a partial laser in?situ keratomileusis flap amputation over the visual axis
摘要： We describe the use of topography-guided transepithelial phototherapeutic keratectomy (PTK) to restore excellent uncorrected distance visual acuity (UDVA) in an eye with extremely irregular topography as a result of a severe complication during laser in situ keratomileusis (LASIK) flap creation. Three months before the patient presented to our clinic, the microkeratome cut outward during LASIK flap creation, amputating the partially cut flap across the visual axis. Without a flap cut into the preserved one half of the cornea, complete flap amputation was not considered a safe option. Topography-guided transepithelial PTK was used to regularize the cornea and treat the resulting irregular astigmatism. Six months postoperatively, the cornea remained stable and the UDVA was 6/6C2.
关键词： flap amputation,PTK,LASIK,irregular astigmatism,topography-guided transepithelial phototherapeutic keratectomy
更新于2025-09-12 10:27:22
-
Process optimization for improving topography quality and manufacturing accuracy of thin-walled cylinder direct laser fabrication
摘要： Direct laser fabrication (DLF) known as the additive manufacturing technology was employed in this paper; the optimal methods of generating thin-walled cylinders were researched. The building accuracy was analyzed via employing three main optimal strategies, scanning strategy (S), laser power adjustment (L) and Helical scanning optimization (H), and their interaction effects (SL, LH, HS, SHL). In addition, synclastic scanning strategy (method 1), reversed scanning strategy (method 2), and new collative variable of Z-axis increment (method 3) combining with those optimal tactics were verified by fewer defections and greater performance. As a result, method 1SHL and method 2SL are proven to be the best method to optimize the process to fabricate thin-walled cylinders.
关键词： Optimal strategy,Topography precision,Thin-walled cylinder,Direct laser fabrication
更新于2025-09-12 10:27:22
-
Variation of Surface Topography in Laser Powder Bed Fusion Additive Manufacturing of Nickel Super Alloy 625
摘要： This document provides details on the files available for download in the dataset “Variation of Surface Topography in Laser Powder Bed Fusion of Nickel Super Alloy 625.” The following sections provide details on the experiments, methods, and data files. The experiment detailed in this document methodically varies part position and surface orientation relative to the build plate and relative to the recoater blade. This dataset provides surface height data for analysis and development of correlations by the greater research community.
关键词： additive manufacturing,focus variation,IN625,surface texture,surface topography,nickel super alloy 625,laser powder bed fusion
更新于2025-09-11 14:15:04
-
Three‐dimensional reconstruction of fluvial surface sedimentology and topography using personal mobile laser scanning
摘要： This investigation compares a personal mobile laser scanning (MLS) survey using a Leica Pegasus Backpack that integrates Velodyne Puck VLP-16 sensors, and a multi-station Terrestrial Laser Scanning (TLS) survey. Independent check points and a cloud-to-cloud comparison indicated that personal MLS had similar vertical errors to static TLS. Analysis of wearable laser scanning point cloud variability enabled the mapping of surface sedimentology. Where terrain is navigable by foot, wearable laser scanning enables rapid acquisition of point cloud data.
关键词： sedimentology,morphodynamics,topography,Personal mobile laser scanning,terrestrial laser scanning
更新于2025-09-11 14:15:04
-
MICRO WAVE PATTERNS BY VIBRATING-LENS ASSISTED LASER MACHINING
摘要： Surfaces with superimposed patterns offer, in many applications, numerous advantages over traditional smooth surfaces since they profoundly affect functional behavior, e.g., friction, wettability, etc. Different shapes and sizes of surface patterns were fabricated by traditional laser machining, however, micro wave patterns are difficult to generate by this process. In this paper, vibrating-lens assisted laser machining is proposed to generate such patterns and to extend its capabilities. A model, based on the traditional heat-flow principle, was built to ascertain the energy distribution in the process and predict the shape of the wavy patterns generated. A specially developed experimental setup was used for model validation. Sinusoidal wave patterns were analyzed as an example to demonstrate geometrical feature under different parameters and the feasibility of the process. The feasibility of the proposed theoretical and experimental methodologies was illustrated through a comparative analysis of experimental and simulation scenarios.
关键词： Pattern simulation,Surface topography,Vibrating-lens,Laser machining,Traditional heat-flow principle
更新于2025-09-11 14:15:04
-
Stability of corneal topography and aberrometry after hyperopic laser in situ keratomileusis with a 500-Hz excimer laser platform: A 3-year follow-up study
摘要： The aim of this study is to analyze the long-term stability of the corneal topography, the functional optical zone, and the refractive stability throughout 3 years following laser in situ keratomileusis surgery for hyperopia using a 500-Hz excimer laser system. This retrospective consecutive observational case series study comprised 66 eyes that underwent laser in situ keratomileusis to correct hyperopia with a postoperative follow-up of 3 years. Laser in situ keratomileusis procedures were performed using the SCHWIND Amaris 500-Hz excimer laser. Main outcomes measured were stability of the functional optical zone at corneal topography and corneal aberrometry. Statistically significant differences were found in simulated keratometry (K2 (steep meridian) and Km (mean keratometry)) between 3 and 36 months postoperatively (p ? 0.01); these differences disappeared at 12 and 36 months (p ? 0.18). No statistically significant changes were observed in the horizontal and vertical diameter of the functional optical zone throughout the whole follow-up (p ? 0.07). A statistically significant difference was found in the spherical aberration between 3 and 36 months (p = 0.02); this difference disappeared when compared between 12 and 36 months (p = 0.72). Statistically significant correlations were detected between the vertical functional optical zone and coma root mean square (r = –0.510, p < 0.01) and between the vertical functional optical zone and spherical aberration (r = 0.441, p = 0.02) 36 months after surgery. Following 3 years of hyperopic laser in situ keratomileusis with a 500-Hz Amaris excimer laser, keratometry, functional optical zone, and corneal aberrations remain stable from 1 year after surgery. Topographical regression is not observed in hyperopic laser in situ keratomileusis with this excimer laser technology from 1 year after surgery.
关键词： corneal topography,refractive surgery,hyperopic laser in situ keratomileusis,hyperopia,Functional optical zone,corneal aberrations,hyperopic regression
更新于2025-09-11 14:15:04