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- 2015
- YAG capsulotomy
- Ultra-late capsular bag distension syndrome
- Post- cataract complication
- Ophthalmology and Vision Science
- Post Graduate Institute of Medical
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Comparison of Neurovascular Coupling between Normal Tension Glaucoma Patients and Healthy Individuals with Laser Speckle Flowgraphy
摘要： Background The purpose of this pilot study was to investigate the differences in neurovascular coupling between Caucasian patients with normal tension glaucoma (NTG) and healthy subjects (HS) with Laser Speckle Flowgraphy (LSFG). Methods Measurement of optic nerve head blood flow was performed with LSFG. Mean blur rate of the whole optic nerve head (MA), of the big retinal vessels (MV) and of the microvasculature (MT) was analysed during continuous flicker light stimulation for four minutes. Results We included 12 eyes from 12 Caucasian patients with diagnosis of normal tension glaucoma and 12 eyes from 12 age- and sex-matched healthy individuals. MA, MV and MT all increased significantly in both groups during the observation period with no difference between the groups. Conclusion Neurovascular coupling is detectable in NTG patients. Flicker light stimulation leads to a comparable increase in ocular blood flow in glaucoma patients and healthy individuals.
关键词： flicker,laser speckle flowgraphy,ocular perfusion,normal tension glaucoma,neurovascular coupling
更新于2025-09-19 17:13:59
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Influence of surface tension on the molten pool morphology in laser melting
摘要： The surface tension plays an important role in the distribution and evolution of molten pool morphology during laser melting. In this paper, based on the theory of Smoothed Particles Hydrodynamics (SPH), a mathematical model of surface tension on the molten pool morphology is established with the temperature change of molten pool being taken into account. The longitudinal morphology of molten pool and its formation process are simulated by using the SPH method under certain processing parameters, and the distributions of length and depth of molten pool are thoroughly analyzed at various processing parameters. The result shows that the longitudinal morphology of molten pool varying along the longitudinal section of solidified track presents a curve due to the influence of surface tension. A strong influence of Marangoni force on the flow of liquid metal and transformation of heat is also found. Moreover, the longitudinal morphology of a molten pool looks like that of a wave in the simulation; the deformation distributions of the longitudinal morphology of molten pool will increase with increasing laser power or decreasing scanning speed. The longitudinal morphologies of solidified molten pool are observed in the current experiments, and the experimental results are found to be agreed well with the calculated ones.
关键词： Processing parameters,Laser melting,Smoothed particles hydrodynamics (SPH),Molten pool morphology,Surface tension
更新于2025-09-16 10:30:52
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Differences in Optic Nerve Head Blood Flow Regulation in Normal Tension Glaucoma Patients and Healthy Controls as Assessed With Laser Speckle Flowgraphy During the Water Drinking Test
摘要： Précis: Optic nerve head (ONH) perfusion was not signi?cantly altered in subjects with normal tension glaucoma (NTG) nor in healthy individuals after performing the water drinking test (WDT), because of its limited effect on ocular perfusion pressure (OPP). Purpose: ONH blood ?ow can be maintained stable in healthy individuals because of a physiological phenomenon called autoregulation. Impairment of autoregulation has been shown especially under condition of NTG. The purpose of this study was to investigate the ONH blood ?ow autoregulation in patients with NTG by in?uencing the OPP with the WDT. Methods: The study included 9 eyes from 9 white patients with a diagnosis of NTG and 9 eyes from age-matched and sex-matched healthy individuals. In the glaucoma group, the antiglaucomatous therapy was paused 3 weeks before the investigations. Measurements of ONH blood ?ow were performed with laser speckle ?owgraphy. After baseline measurements, individuals ingested 800 mL of water in <5 minutes. Measurements were repeated after 15, 30, and 45 minutes. Results: The water ingestion led to a signi?cant rise in intraocular pressure (P < 0.001) but also mean arterial pressure (P < 0.001) in both groups. This resulted in stable OPP (P = 0.051) with no signi?cant difference between the groups (P = 0.43). ONH blood ?ow remained stable over time in both groups (P = 0.719). No signi?cant interaction of time and group was shown for all parameters. Conclusions: Our ?ndings show that the WDT does not signi?cantly in?uence the OPP and therefore has to be considered inferior to other methods used to assess blood ?ow autoregulation.
关键词： laser speckle ?owgraphy,normal tension glaucoma,water drinking test,blood ?ow regulation
更新于2025-09-12 10:27:22
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Analysis of surface tension driven flow and solidification behavior in laser linear welding of stainless steel
摘要： A transient three-dimensional thermal-?uid-metallurgy model was proposed to study the surface tension driven ?ow and welding metallurgical behavior during laser linear welding of 304 stainless steel. Numerical simulation and experimental method were both used to investigate the thermal behavior, surface tension driven ?ow, driving mechanism and solidi?cation characteristics. The temperature related driving force was qualitatively analyzed, and surface tension and surface shear stress were quantitatively studied. Numerical method and dimensional analysis were also carried out to understand the importance of di?erent driving forces, respectively. The metallurgical model was sequentially coupled to the thermal-?uid model to calculate four solidi?cation parameters. Temperature gradient was observed to be much larger at the front of the melt pool due to the e?ect of thermal conductivity, and decreased from center to the periphery. Both the surface tension and surface tension driven ?ow were found smaller in the central area. The maximum shear stress may reach 2500 N/m2 and pushed an intense outward convection. The solidi?cation parameters were used to predict the solidi?ed morphology, and the prediction was well validated by experimental results. The obtained basic conclusions in this work demonstrated that this study of thermal-?uid-metallurgical behavior could provide an improved understanding of the surface tension driven ?ow and solidi?cation behavior inside the melt pool of welding and additive manufacturing process.
关键词： Solidi?cation behavior,Surface tension,Driving force,Additive manufacturing,Fluid ?ow
更新于2025-09-12 10:27:22
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Size-controlled Patterning of Single-crystalline Perovskites Arrays toward Tunable High-performance Microlaser
摘要： Single-crystalline halide perovskites with regular morphology are of great significance for laser applications because they can be used to fabricate a natural whispering-gallery-mode resonator. Although enormous efforts have been put to synthesize single-crystalline perovskites, controlling the lateral size and thickness of the crystal, particularly at the nanoscale, is still challenging. Here, we report a facile and high-throughput strategy to selectively one-step create micro/nanoscale size-controlled all-inorganic perovskite single-crystal arrays by surface-tension-confined evaporative assembly. Our method can be used to easily tune the single crystal size and selectively position the single crystal, with versatility in fabricating perovskite single-crystal arrays in wafer scale. When the patterned size increases from 2 to 25 μm, the width of the CsPbClBr2 perovskite microplates increased from 150 nm to 4.2 μm. Fixing the width of the microplates at 1.6 μm, with the increase of the sliding speed from 50 to 250 mm/min, we could significantly control the thicknesses from 270 nm to 430 nm. Additionally, our present study provides a characterization of lasers based on different three-dimensional structures, confirming their width-dependence lasing mode and thickness-dependence lasing threshold characteristic, which is beneficial for the tunability of high-performance microlaser.
关键词： microlaser,surface-tension-confined,single crystal,halide-perovskite,evaporative assembly
更新于2025-09-12 10:27:22
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Tunable Spreading and Shrinking on Photocontrolled Liquid Substrate
摘要： Droplets of n-hexadecane were observed to shrink under ultraviolet (365 nm) and spread under blue light (475 nm) irradiation on an aqueous solution of photosensitive surfactant AzoTAB. We demonstrate that the change of wettability of n-hexadecane droplet on the solution depends on the change of oil?water interface tension. According to the addition of ethanol into the substrate, the change of relative diameter ΔD/D exceeds 20%, much larger than the system without ethanol. With light-emitting diode (LED) light as a sole power source, without any other triggers, we provide a contactless and isothermal method to realize photocontrolled alternative spreading and shrinking of a droplet on a liquid surface, which provides a basis for a chromocapillary-based optical zoom liquid lens.
关键词： photosensitive surfactant AzoTAB,oil?water interface tension,optical zoom liquid lens,n-hexadecane,UV/blue light irradiation,chromocapillary effect
更新于2025-09-12 10:27:22
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31.2: <i>Invited Paper:</i> Advanced Materials Development for Ink‐Jet Printed OLEDs
摘要： High-performance, ink-jet printable OLED materials have been successfully developed. Our wide libraries of platforms and small molecule hosts were effective for improving efficiency and lifetime of OLEDs. For wide color gamut, new emitters with deep in color and narrow full-width at half maximum were developed. Further, solvent systems having physical properties suitable for improving film uniformity in pixels were found.
关键词： Small molecule,FWHM,Viscosity,Red emitter,Surface tension,Platform,Film-uniformity,PLQY,Ink-jet,OLED
更新于2025-09-12 10:27:22
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Stress-induced refractive index changes in laser fibers and preforms
摘要： Refractive index profile of the core is a key design parameter in fiber lasers and amplifiers. During manufacturing, the initial information of the index profile is obtained from the preform, while ultimately the performance is defined by the index profile of the fiber. Depending on stresses and diffusion, the two profiles may be different. It is possible to predict more accurately the laser fiber refractive index when we apply a stress-induced index change model to the measured preform index profile data. The improved capability to predict the fiber index from preform increases the confidence in achieving the designed index profile in fiber, which enables faster process feedback and higher fiber yields.
关键词： laser fiber,tension,optical fiber,modelling,thermal stress,preform,Refractive index change,DND,stress
更新于2025-09-11 14:15:04
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[IEEE 2018 Iranian Conference on Electrical Engineering (ICEE) - Mashhad (2018.5.8-2018.5.10)] Electrical Engineering (ICEE), Iranian Conference on - Theoretical and Simulational Study of Electrowetting on Dielectric (EWOD) Effect
摘要： Electrowetting mechanism has been recently employed to enhance the manipulation process in biomedical engineering. In this research, we have described the Electrowetting on thermodynamic Dielectric phenomenon by using classical approach. The droplet motion has been numerically studied by finite element method. The electrowetting mechanism has been investigated by solving the coupled electrostatic and droplet physics. Simulation results revealed 50 V threshold voltage for the system. The droplet velocity increases linearly by increasing the applied electric field and the maximum velocity of 0.04 mm/s has been achieved for 250 V excitation voltage. Based on the results, for the above 250 V there is no velocity increases.
关键词： Digital microfluidics,Electrowetting,Contact angle,Electrowetting on dielectric (EWOD),Surface tension,hydrophobic layer
更新于2025-09-11 14:15:04
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Numerical Demonstration of In-Tube Liquid-Column Migration Driven by Photoisomerization
摘要： Droplet manipulation by light-induced isomerization was numerically demonstrated and investigated regarding the driving mechanism. Such a non-invasive manipulation of a droplet in a microchannel can be realized, for example, by the use of watery solution of photoresponsive surfactant that exhibits the isomerization. Due to variable fluid properties between the cis and trans isomers, one-side light irradiation on a liquid column in a tube would lead to some kind of imbalance between the two ends of the liquid column and then drive droplet migration. The present numerical simulations of air–liquid two-phase flow and its scalar transport of the isomer, considering the variable static contact angle, agreed quantitatively with the experimental results in terms of the migration speed. This fact supports the contention that the droplet migration is more likely to be driven by an imbalance in the wettability, or the contact angle. The migration speed was found to be less dependent on the liquid-column length, but proportional to the tube diameter.
关键词： photochemical reaction,non-invasive control,wettability,surface tension,microfluidics,computational fluid dynamics,lab-on-a-chip,droplet manipulation,two-phase flow,photoresponsible surfactant
更新于2025-09-09 09:28:46