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Laser and Anti–Vascular Endothelial Growth Factor Agent Treatments for Retinal Arterial Macroaneurysm
摘要： Purpose: to describe the efficacy of laser and intravitreal injection of anti?vascular endothelial growth factor (anti-VEGF) agents for patients with symptomatic retinal arterial macroaneurysm (RAM). Design: From 2009 to 2016, we collected patients with exudative or hemorrhagic RAM all treated by focal laser photocoagulation. Methods: Nd:YAG laser was performed in patients with subinternal limiting membrane (sub-ILM) hemorrhage. Intravitreal anti-VEGF agents were given in eyes with macular exudation as adjuncts. Changes of visual acuity and central foveal thickness before and after treatment were recorded and compared with Wilcoxon signed-rank test. Results: Thirty-five eyes that underwent a single session of laser photocoagulation for RAM resulted in macroaneurysm regression. The hemorrhagic group included 24 eyes having ruptured macroaneurysms without macular exudation. Five eyes with simultaneous sub-ILM hemorrhage receiving Nd:YAG laser membranotomy had resolution of preretinal hemorrhage. Exudative RAM having cystoid macular edema or submacular fluid with or without ruptured macroaneurysms was treated by focal laser photocoagulation alone in 3, or combined with single intravitreal anti-VEGF agent in 8 eyes. All patients had significantly improved vision when comparing visual acuity at baseline and final follow-up (P = 0.00016). Significant reduction of macular thickness was also observed after laser monotherapy or combined treatment in exudative RAM (P = 0.018). Conclusions: Focal laser photocoagulation was helpful for the management of ruptured or leaky RAM. Combined focal laser and intravitreal anti-VEGF agents could better reduce macular exudation caused by RAM. Additionally, Nd:YAG laser was a safe and effective method to remove the sub-ILM hemorrhage caused by RAM.
关键词： retinal arterial macroaneurysm,argon laser,bevacizumab,aflibercept
更新于2025-09-11 14:15:04
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Precise sputtering of silicon dioxide by argon cluster ion beams
摘要： In this work, the sputtering yields of SiO2 by the argon cluster ion beam with incident angles 0° and 45° have been studied experimentally. The kinetic energy of the primary cluster ions was in the range of E = 5–23.5?keV, and the mean cluster size was Nmean = 100–1000 atom/cluster. It is found that, when the energy per cluster atom quantity E/N is comparable to the binding energy of the solid (of the order of several eV), the yields of atoms sputtered per primary atom Y/N, at the incident angle 45°, is 4 times greater than at normal incidence. Conversely, when energy E/N is significantly above the binding energy of the solid (~ 100?eV), the sputtering yields for the incident angles 0° and 45° have the same values.
关键词： kinetic energy,incident angles,argon cluster ion beam,sputtering yields,cluster size,silicon dioxide
更新于2025-09-10 09:29:36
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Measurement of Argon emission spectral of ICP plasma using a diagnostic system based on photomultiplier tubes array
摘要： Optical emission spectroscopy (OES) is one of the most important diagnostic tools in plasma physics. A self-built spectroscopic diagnostic system, owning temporal and spatial resolution, has been constructed using photo multiplier tubes (PMTs) array, spectrometer and other parts. The problem of superposition between inlet plane of bundle fiber and the focal plane of the spectrometer is analyzed and solved. In addition, the synchronization regulation of output of PMTs has been completed. This system is installed on an inductively coupled (ICP) plasma chamber in order to study the Argon (Ar) emission spectrum generated from typical radio frequency (RF) and pulse discharges. The test results show that the intensity of Ar emission spectrum increases with the power and pressure, but increase less with the flow and current ratio. Under pulse discharge condition, the intensity of spectrum does not change with the frequency, neither does the broadening of spectrum with time.
关键词： PMTs array,ICP plasma,Argon emission spectrum,Optical emission spectroscopy,RF and pulse discharges
更新于2025-09-10 09:29:36
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Emittance Preservation in an Aberration-Free Active Plasma Lens
摘要： Active plasma lensing is a compact technology for strong focusing of charged particle beams, which has gained considerable interest for use in novel accelerator schemes. While providing kT=m focusing gradients, active plasma lenses can have aberrations caused by a radially nonuniform plasma temperature profile, leading to degradation of the beam quality. We present the first direct measurement of this aberration, consistent with theory, and show that it can be fully suppressed by changing from a light gas species (helium) to a heavier gas species (argon). Based on this result, we demonstrate emittance preservation for an electron beam focused by an argon-filled active plasma lens.
关键词： active plasma lensing,argon,helium,aberration-free,emittance preservation
更新于2025-09-10 09:29:36
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Particle-in-cell/Monte Carlo collisional simulation of negative streamer formation and branching between planar electrodes
摘要： In this paper, the mechanism of negative streamer formation and branching between planar electrodes is studied using a two dimensional particle-in-cell/Monte Carlo collisional model. Super-particles, each one of which represents many physical particles, are used in our model to reduce the calculation and memory usage. The electric field applied to the gap between electrodes is constant and is above the breakdown value already before the streamer formation. For nitrogen at standard temperature and pressure, the simulation is first performed in the background field of 10 MV/m. The results show that prior to branching, the streamer head is flattened, and the non-uniform distribution of electrons accelerated to energies above 50 eV is obtained at the flat streamer head, which then leads to streamer branching. Then, additional simulations in the background fields of 9 MV/m, 11 MV/m, and 12 MV/m are performed to investigate the effects of background field. The results show that the streamer propagates faster, has larger plasma density, and branches more rapidly in a stronger field. The simulation results of argon are also given at a standard temperature and pressure in the background field of 10 MV/m. The results show that more branches can be obtained in argon compared with nitrogen, which agrees well with the experimental results.
关键词： particle-in-cell,nitrogen,argon,Monte Carlo collisional model,negative streamer,branching
更新于2025-09-10 09:29:36
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Gastric Hemangioma Treated with Argon Plasma Coagulation in a Newborn Infant
摘要： Gastric hemangioma in the neonatal period is a very rare cause of upper gastrointestinal bleeding. We present a case of hemangioma limited to the gastric cavity in a 10-day-old infant. A huge, erythematous mass with bleeding was observed on the lesser curvature side of the upper part of the stomach. Surgical resection was ruled out because the location of the lesion was too close to the gastroesophageal junction. Medical treatment with intravenous H2 blockers, octreotide, packed red blood cell infusions, local epinephrine injection at the lesion site, application of hemoclip, and gel-form embolization of the left gastric artery did not significantly alter the transfusion requirement. Hemostasis was achieved with endoscopic argon plasma coagulation (APC). After two sessions of APC, complete removal of the lesion was achieved. APC was a simple, safe and effective tool for hemostasis and the ablation of gastric hemangioma without significant complications.
关键词： Neonate,Hemangioma,Stomach,Argon plasma coagulation
更新于2025-09-04 15:30:14
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Internal Energy Distribution of Secondary Ions Under Argon and Bismuth Cluster Bombardments: “Soft” Versus “Hard” Desorption–Ionization Process
摘要： The emission/ionization process under massive argon cluster bombardment was investigated by measuring the internal energy distributions of a series of benzylpyridinium ions. Argon clusters with kinetic energies between 10 and 20 keV and cluster sizes ranging from 500 to 10,000 were used to establish the influence of their size, energy, and velocity on the internal energy distribution of the secondary ions. It is shown that the internal energy distribution of secondary ions principally depends on the energy per atom or the velocity of the cluster ion beam (E/n ∝ v2). Under low energy per atom (E/n ? 10 eV), the mean internal energy and fragmentation yield increase rapidly with the incident energy of individual constituents. Beyond 10 eV/atom impact (up to 40 eV/atom), the internal energy reaches a plateau and remains constant. Results were compared with those generated from bismuth cluster impacts for which the mean internal energies correspond well to the plateau values for argon clusters. However, a significant difference was found between argon and bismuth clusters concerning the damage or disappearance + impact cross section. A 20 times smaller disappearance cross section was measured under 20 keV Ar2000 + bombardment, thus quantitatively showing the low damage effect of large argon clusters compared to 25 keV Bi5 for almost the same molecular ion yield.
关键词： Bismuth cluster,Argon cluster,Internal energy,TOF-SIMS,Benzylpyridinium ion
更新于2025-09-04 15:30:14
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A new approach to studying the luminescence spectra of free icosahedral and crystalline argon nanoclusters
摘要： We propose a new approach to analyzing the cathodoluminescence spectra of free argon nanoclusters, forming in a supersonic jet flowing into vacuum. Based on this approach, we conduct an analysis of the intensities of the luminescence bands of neutral and charged excimer complexes (Ar2)* and (Ar+4)*, measured for clusters with an average size ranging from 500 to 8900 atoms per cluster, and a diameter of 32–87 A? . It is shown that the concentration of the substance condensed into clusters, which determines the integrated intensity of the bands, is proportional to the logarithm of the average size of the clusters in the jet. An analysis of the normalized intensities of the (Ar2)* and (Ar+4)* bands for crystalline clusters with an fcc structure allowed us to establish that the luminescence of neutral (Ar2)* molecules comes from within the volume of the cluster, while the charged complexes (Ar+4)* emit from the subsurface layer. We highlighted an area of cluster dimensions at which the jet is dominated by quasi-crystalline clusters with an icosahedral structure, and it is shown that the transition from icosahedral clusters to fcc structures occurs when the average size of the cluster in the jet is (cid:2)N = (1000–1800) atoms/cluster.
关键词： cathodoluminescence,argon nanoclusters,luminescence spectra,excimer complexes,supersonic jet
更新于2025-09-04 15:30:14