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oe1(光电查) - 科学论文

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出版时间
  • 2015
研究主题
  • YAG capsulotomy
  • Ultra-late capsular bag distension syndrome
  • Post- cataract complication
应用领域
  • Ophthalmology and Vision Science
机构单位
  • Post Graduate Institute of Medical
27 条数据
?? 中文（中国） ▾

  • Fibre Bragg grating sensor applications for structural health monitoring

    摘要： Purpose – Structural health monitoring (SHM) has become an attractive subject in aerospace engineering ?eld considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures. Design/methodology/approach – Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the ?nite element analyses conducted using ABAQUS? software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors. Findings – The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed. Practical implications – Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications. Originality/value – This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.

    关键词： Torsion test,Tension test,Structural health monitoring,Composite beams,Fibre Bragg grating sensors

    更新于2025-09-23 15:22:29

  • Patterns of Subsequent Progression of Localized Retinal Nerve Fiber Layer Defects on Red-free Fundus Photographs in Normal-tension Glaucoma

    摘要： Purpose: To investigate patterns of subsequent progression of localized retinal nerve fiber layer (RNFL) defects and to quantify the extent of progression in normal-tension glaucoma (NTG) patients. Methods: Thirty-three eyes of 33 consecutive NTG patients who had shown continuous progression of localized RNFL defect on serial red-free fundus photographs were selected for the study. Patterns of subsequent progression of localized RNFL defects were categorized, and extents of progression were quantified. Serial evaluations of disc stereophotographs and visual fields were also performed to detect progression. Results: The most common pattern was continuous widening of the defect towards the macula (n = 11, 33.3%) followed by sharpening of the defect border after widening of the defect towards the macula (n = 5, 15.2%), continuous widening of the defect away from the macula (n = 2, 6.1%), and deepening of the defect after appearance of a new defect (n = 2, 6.1%). Four eyes (12.1%) simultaneously showed two patterns of subsequent progression. In 13 eyes that showed continuous widening of the defect, subsequent angular widening towards the macula and away from the macula were 9.2 ± 6.0° (range, 1.1° to 24.4°; n = 11) and 5.2 ± 4.9° (range, 0.3° to 11.3°; n = 2), respectively. Thirty-two eyes showed no progression of optic disc cupping. Out of the 21 eyes in which Humphrey central 30-2 threshold visual field tests were performed after progression of RNFL defects, 15 eyes showed no deterioration in the visual field. Conclusions: There were nine patterns of subsequent progression of localized RNFL defects. Among them, continuous RNFL loss proceeding temporally was the most common one. Initial progression of the defect proceeded temporally, especially in the defect located at the inferior fundus, might be at a risk of further RNFL loss temporally.

    关键词： Nerve fibers,Low tension glaucoma,Progression

    更新于2025-09-23 15:22:29

  • Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat

    摘要： PURPOSE. Oxygen extraction fraction (OEF), defined by the ratio of oxygen metabolism (MO2) to delivery (DO2), determines the level of compensation of MO2 by DO2. In the current study, we tested the hypothesis that inner retinal OEF remains unchanged during light flicker under systemic normoxia and hypoxia in rats due to the matching of MO2 and DO2. METHODS. Retinal vascular oxygen tension (PO2) measurements were obtained in 10 rats by phosphorescence lifetime imaging. Inner retinal OEF was derived from vascular PO2 based on Fick's principle. Measurements were obtained before and during light flicker under systemic normoxia and hypoxia. The effects of light flicker and systemic oxygenation on retinal vascular PO2 and OEF were determined by ANOVA. RESULTS. During light flicker, retinal venous PO2 decreased (P < 0.01, N = 10), while inner retinal OEF increased (P = 0.02). Under hypoxia, retinal arterial and venous PO2 decreased (P < 0.01), while OEF increased (P < 0.01). The interaction effect was not significant on OEF (P = 0.52), indicating the responses of OEF to light flicker were similar under normoxia and hypoxia. During light flicker, OEF increased from 0.46 ± 0.13 to 0.50 ± 0.11 under normoxia, while under hypoxia, OEF increased from 0.67 ± 0.16 to 0.74 ± 0.14. CONCLUSIONS. Inner retinal OEF increased during light flicker, indicating the relative change in DO2 is less than that in MO2 in rats under systemic normoxia and hypoxia. Inner retinal OEF is a potentially useful parameter for assessment of the relative changes of MO2 and DO2 under physiologic and pathologic conditions.

    关键词： vascular oxygen tension,retina,oxygen extraction fraction,hypoxia,light flicker

    更新于2025-09-23 15:22:29

  • Continuous 24-hour ocular dimensional profile recording in medically treated normal-tension glaucoma

    摘要： Purpose: To analyze the 24-hour ocular dimensional profile in normal-tension glaucoma (NTG) patients on medical treatment. Methods: Consecutive, medically treated NTG subjects were recruited from a university eye center. Subjects were on a mean of 1.7±0.7 types of antiglaucoma medications and 56.6% were on a prostaglandin analog. A contact lens-based sensor device was worn in one eye of NTG patients to record the intraocular pressure (IOP)-related profile for 24 hours, recording the following: variability from mean over 24 hours, nocturnally and diurnally, as well as the number of peaks and troughs diurnally and nocturnally. Results: In 18 NTG subjects, the nocturnal variability around the mean contact lens-based sensor device signal was 48.9% less than the diurnal variability around the mean. The number of peaks was 54.7% less during the nocturnal period than during the diurnal period. The rate of increase in the ocular dimensional profile when going to sleep was significantly greater than the rate of decrease upon waking (P<0.001). Conclusion: In medically treated NTG subjects, there was more variability in the IOP-related pattern during the daytime and there were fewer peaks during sleep.

    关键词： intraocular pressure,24-hour,normal tension glaucoma

    更新于2025-09-23 15:22:29

  • Interfacial Tensions and Viscosities in Multiphase Systems by Surface Light Scattering (SLS)

    摘要： Hypothesis Multiphase systems are relevant in many fields of process engineering. For process and product design in connection with multiphase systems, knowledge on the thermophysical properties of the individual phases such as viscosity and on the interfacial tension between these is required but often lacking in literature. Experiments In the present study, the applicability of surface light scattering (SLS) for the simultaneous measurement of interfacial tensions and viscosities in multiphase systems in macroscopic thermodynamic equilibrium is demonstrated. For two model systems consisting of n-decane and methanol as well as n-dodecane and methanol forming a vapor-liquid-liquid equilibrium at atmospheric pressure, surface fluctuations which show an oscillatory behavior at the vapor-liquid and liquid-liquid interface could be associated with hydrodynamic modes. Findings From an exact theoretical description of the dynamics of the surface fluctuations, absolute data for the dynamic viscosities of the two liquid phases as well as the vapor-liquid and liquid-liquid interfacial tensions could be determined at temperatures between (333 and 358) K with total measurement uncertainties (k = 2) down to about 2%. For both systems studied at temperatures close to the upper critical solution temperature, the viscosities of the two liquid phases approach each other and the liquid-liquid interfacial tension tends to zero.

    关键词： liquid-liquid systems,interfacial tension,multiphase systems,interfaces,upper critical solution temperature,vapor-liquid systems,viscosity,surface light scattering

    更新于2025-09-23 15:21:21

  • Self-propelled water droplet movement on a laser-etched radial gradient copper surface

    摘要： This paper reports the behavior of water droplets on a topography-based, radial gradient on a metallic surface. The radial gradient was designed to concentrate water in the center region through the spontaneous motion and coalescence of individual droplets on the gradient pattern. In this work, parallel microchannels having a fixed width (~25 μm) and depth (100 μm) but variable spacing were used to impart a net surface tension force to the droplet for actuation. The diameter of the radial gradient (i.e. circular test region) was approximately 18.9 mm (or, ~0.75 in.). The surfaces were fabricated using a 355 nm YVO4 laser system and then characterized using droplet injection (5–38 μL) and spray testing techniques. Injected droplets were observed to move spontaneously away from the hydrophobic outer ring region of the circle towards the hydrophilic center as designed by the gradient. Droplet travel distances as large as 4 mm were measured depending on the droplet volume and injection site location. In application, such a design could be useful for promoting droplet coalescence on a surface and subsequently removal by gravity through the formation of sufficiently large droplets from two or more otherwise small droplets.

    关键词： Surface tension gradient,Microchannels,Condensation,Heat exchangers,Radial pattern,Laser etching,Water droplet

    更新于2025-09-23 15:21:01

  • Grain size dependence of tensile properties in nanocrystalline diamond

    摘要： Nanocrystalline diamond (NCD) is a promising material due to its extraordinary mechanical properties, however, the research on the dependence of mechanical properties on the grain size (d) of NCD is still limited. In this paper, the mechanical behavior of 3D NCD with various d is investigated using molecular dynamics (MD) simulations. It was found that the mechanical properties of NCD are sensitive to d. The Young's modulus (E) increases with the increase of d due to the increasing fraction of grain interiors (GIs), while the failure strain (εf) decreases with the increase of d due to the decreasing fraction of grain boundaries (GBs). It was also found that the failure strength (σf) decreases with the increase of d, which could be attributed to that for larger d the stress concentration in the GBs is severer, which may make cracks initiate more easily. Similar to εf and σf, the deformation work density was found to increase with the decrease of d, indicating the enhancement of toughness of NCD when d is small. For the samples of different d, the nucleation and propagation of both transgranular and intergranular cracks are the main failure mechanisms, which is consistent with experimental observations.

    关键词： Molecular dynamics simulation,Mechanical property,Nanocrystalline diamond,Tension,Grain size

    更新于2025-09-23 15:21:01

  • Data on eosin Y solutions for laser-induced fluorescence in water flows

    摘要： Dye tracing techniques involve the tagging of a sample of water with dye, providing important qualitative and quantitative information. This article presents physical and fluorescence properties of dye solutions obtained by diluting a pharmaceutical aqueous solution of eosin Y with distilled water. Sample solutions with eosin concentrations ranging from 0 to 20 g/L were examined under various temperatures and laser powers. The data include measurements of dynamic viscosity, surface tension and pH. Fluorescence emission spectra as well as laser beam attenuation and photobleaching measurements are also reported. The datasets provide guidelines for obtaining optimal dye mixtures and suitable optical configurations to implement eosin fluorescence techniques.

    关键词： Dye-water solution,Surface tension,Viscosity,Laser-induced fluorescence,pH

    更新于2025-09-23 15:19:57

  • Laser-Profiled Continuum Robot with Integrated Tension Sensing for Simultaneous Shape and Tip Force Estimation

    摘要： The development of miniaturized continuum robots has a wide range of applications in minimally invasive endoluminal interventions. To navigate inside tortuous lumens without impinging on the vessel wall and causing tissue damage or the risk of perforation, it is necessary to have simultaneous shape sensing of the continuum robot and its tip contact force sensing with the surrounding environment. Miniaturization and size constraint of the device have precluded the use of conventional sensing hardware and embodiment schemes. In this study, we propose the use of optical fibers for both actuation and tension/shape/force sensing. It uses a model-based method with structural compensation, allowing direct measurement of the cable tension near the base of the manipulator without increasing the dimensions. It further structurally filters out disturbances from the flexible shaft. In addition, a model is built by considering segment differences, cable interactions/cross talks, and external forces. The proposed model-based method can simultaneously estimate the shape of the manipulator and external force applied onto the robot tip. Detailed modeling and validation results demonstrate the accuracy and reliability of the proposed method for the miniaturized continuum robot for endoluminal intervention.

    关键词： modeling,continuum robot,endoluminal intervention,tension-sensing cable,shape and force sensing

    更新于2025-09-23 15:19:57

  • Microhole Formation Behavior of Polypropylene Film Using CO<sub>2 </sub>Laser Irradiation

    摘要： Biaxially oriented polypropylene films produced by simultaneous equi-biaxial stretching to the draw ratio of 4 (cid:186) 4 were perforated by the carbon dioxide laser under various laser fluences up to 426.3 J/cm2. After applying various laser fluences, the irradiated area was observed using a laser scanning confocal microscope. With the increase of fluence, the surface deformation with the formation of a crater surrounded by a doughnut-like rim was firstly observed at the laser fluence of 49.7 J/cm2, followed by the starting of the formation of a microhole surrounded by the rim at 113.7 J/cm2. The diameter of the microhole and the size of the rim increased rapidly with the increase of laser fluence. Mechanisms for the formation of a crater, the opening of a microhole, and the formation of surrounding rim were considered to be related to the surface tension and the shrinkage caused by molecular orientation relaxation. On the other hand, volume loss from the laser irradiated area was negligibly small at the moment of microhole opening, and started to increase rapidly when the fluence reached around 150 J/cm2. The microhole formation behavior was also observed by a high-speed camera. The velocity of microhole opening increased rapidly at first, presumably during the laser irradiation, and then slowed down after the cessation of laser irradiation. Theoretically estimated temperature distribution along the film thickness was compared with the laser perforation behavior. Starting of the deformation of film matched well with the starting of melting of the film surface. Film temperature was lower than the thermal decomposition temperature at the moment of the opening of a microhole, whereas at the moment of the starting of volume loss, film temperature was lower than the decomposition temperature estimated based on the heating rate of laser irradiated area, indicating that the decomposition and vaporization continues for a while after the cessation of laser irradiation.

    关键词： microhole formation,molecular orientation relaxation,Polypropylene,laser fluence,CO2 laser,surface tension

    更新于2025-09-19 17:13:59