- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Synthesis of Porous ZnO Nanosheets and Carbon Nanotube Hybrids as Efficient Photocatalysts via Pulsed Laser Ablation
摘要： Zinc oxide (ZnO) has attractive photocatalytic properties. However, the high recombination rate of the photo-excited charge carriers on this material often restricts application. Here, we report that hybridization of one dimensional (1D) carbon nanotubes (CNT) on two dimensional (2D) porous ZnO nanosheets (NS) can be a promising strategy to overcome some of the challenges of ZnO. Specifically, a pulsed laser ablation technique was utilized to hybridize 1D CNT with 2D porous ZnO NS in environmentally friendly as well as super-economic (short time, less than 10 min) conditions. The synthesized ZnO NS-CNT hybrids show a significantly enhanced photocatalytic activity for water splitting relative to their counterpart ZnO NS.
关键词： pulsed laser ablation,water splitting,carbon nanotube,photocatalyst,zinc oxide,nanocomposites
更新于2025-09-16 10:30:52
-
Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite
摘要： Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10?5 m2/s to 0.1223 × 10?5 m2/s and 0.163 W s1/2 cm?2 K?1 to 0.3192 W s1/2 cm?2 K?1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
关键词： graphene oxide,z-scan,spatial self-phase modulation,Pt-NPs,platinum nanoparticles/graphene oxide composite,laser ablation,photoacoustic,thermal lens
更新于2025-09-16 10:30:52
-
CARS-imaging guidance for fs-laser ablation precision surgery
摘要： Due to ageing populations the number of tumors is increasing worldwide. Successful surgical treatment requires complete resection of tumors to reduce recurrence rates. To reach this goal, novel methods combining in vivo tumor and tumor margin detection with low invasive precision surgical tools are needed. Coherent anti-Stokes Raman scattering (CARS) imaging is a highly promising optical tool for visualizing tumors based on characteristic changes in tissue morphology and molecular composition, while fs-laser ablation is to date the most precise surgical tool established in ophthalmology. In this contribution, CARS imaging has been combined with fs-laser ablation as a new approach for image-guided precision surgery for the first time. CARS guided fs-ablation has been applied to ablate brain, liver, skin, muscular and vascular tissues with μm-precision using sub-100 fs pulses of μJ level. We demonstrate superior imaging performance and contrast as well as detection of tissue margins by coherent Raman microscopy in comparison to laser reflectance imaging. The combination of CARS-image-guided tissue ablation is a promising tool for minimally invasive surgeries particularly in the vicinity of functional structures in the future.
关键词： minimally invasive surgeries,CARS imaging,precision surgery,tumor margin detection,fs-laser ablation
更新于2025-09-16 10:30:52
-
Time-resolved imaging of atoms and molecules in laser-produced uranium plasmas
摘要： Gas-phase oxidation of uranium (U), plume chemistry, and the corresponding impact on optical emission features of the U plasma are investigated. Plasmas were produced via nanosecond laser ablation of a natural U target in a chamber where U oxidation was controlled by varying the oxygen partial pressure in an argon cover gas. Monochromatic imaging of U atoms and monoxide (UO) molecules was performed using narrow bandpass optical filters. Results reveal the spatio-temporal evolution of atomic and molecular species in the plasma. U oxides are found to be formed further from the target (in comparison to U atoms), where lower temperatures favor molecular recombination. Segregation between the distribution of U atoms and UO species is observed at later times of plasma evolution, and is more apparent at lower oxygen partial pressures. At higher oxygen partial pressures, significant variation in plume morphology is noticed for UO species, which can be attributed to the higher oxide (UxOy) formation further from the target. The monochromatic images of U atoms and UO molecules and corresponding spectral features at various oxygen partial pressures presented here provide unique insight into gas-phase, high-temperature U oxidation and chemistry, with implications for a wide range of nuclear applications, from stand-off detection of radioisotopes to forensics and safeguards.
关键词： optical emission spectroscopy,plasma,uranium,laser ablation,monochromatic imaging
更新于2025-09-16 10:30:52
-
In situ sequential U-Pb age and Sm-Nd systematics measurement of natural LREE-enriched minerals using single laser ablation multi-collector inductively coupled plasma mass spectrometry
摘要： In the present work, we describe a sequential U-Pb and Sm-Nd systematics measurement from natural LREE-enriched minerals by using a Neptune Plus MC-ICP-MS coupled with a 193nm excimer laser in a single shot. The MC-ICP-MS is equipped with zoom optics lens to bring ion beams into the collector coincidently. The key features allow rapid switching between U-Pb and Sm-Nd collector configuration, which is applied to simultaneously measure the U-Pb age and Sm-Nd isotope of common natural LREE-enriched minerals. The robustness and usefulness of the present protocol is investigated by using a series of well-characterized mineral reference materials (monazite, titanite, perovskite) with known U-Pb and Sm-Nd isotopic values, which demonstrate its potential and versatility in geochemistry and microanalysis for cosmochemistry.
关键词： U-Pb age,LREE-enriched minerals,Sm-Nd isotope,laser ablation,MC-ICP-MS
更新于2025-09-16 10:30:52
-
Calibration-free elemental analysis combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy
摘要： Calibration-free (CF) method combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) was ?rst utilized to realize elemental analysis of alloy samples. A compact ?ber laser operated at 30 kHz pulse repetition rate was used to ablate the sample and the spectra were recorded with a compact ?ber spectrometer in non-gated signal recording mode. Three standard aluminum alloy samples were analyzed to evaluate the performance of this technique. Median ?ltering method was applied to reduce the contribution of the continuum background to the intensity of the atomic lines. The averaged electron density was determined to be (2.36–2.49) × 1017 cm?3 according to the Stark broadening of four ionic lines. 11,800 K averaged plasma temperature was estimated from the Saha-Boltzmann plots. The plasma could be veri?ed to be in a state close to local thermodynamic equilibrium. The analytical error was < 0.5% for the major element and < 35% for minor elements with > 0.1% concentrations. It was demonstrated that CF method combined with HRR LA-SIBS was possible to realize reliable quantitative elemental analysis for aluminum alloy samples.
关键词： Calibration-free,Laser-ablation spark-induced breakdown spectroscopy,Elemental analysis,Aluminum alloy,High repetition rate
更新于2025-09-16 10:30:52
-
Pulsed laser synthesis of highly active Ag–Rh and Ag–Pt antenna–reactor-type plasmonic catalysts
摘要： Ag, Pt, and Rh monometallic colloids were produced via laser ablation. Separate Ag–Rh and Ag–Pt heterostructures were formed by mixing and resulted in groupings of Rh/Pt nanoparticles adsorbing to the concavities of the larger Ag nanostructures. The 400 nm Ag plasmonic absorption peak was slightly blue-shifted for Ag–Pt and red-shifted for Ag–Rh heterostructures. Catalytic activity for the reduction of 4-nitrophenol increased significantly for Ag–Pt and Ag–Rh compared to the monometallic constituents, and persisted at lower loading ratios and consecutive reduction cycles. The enhancement is attributed to the Rh and Pt nanoparticles forming antenna–reactor-type plasmonic catalysts with the Ag nanostructures.
关键词： Pt,catalysis,multicomponent,Rh,nanoparticles,antenna–reactor,4-nitrophenol,heterostructures,Ag,laser ablation,plasmonic
更新于2025-09-16 10:30:52
-
Synthesis of bilayer graphene nanosheets by pulsed laser ablation in liquid and observation of its tunable nonlinearity
摘要： Bilayer graphene nanosheets (B-GNSs) have been synthesized from dry-cell graphite electrode by using facile laser ablation in liquid technique in ambient condition. The plasma plume generated on incidence of ns pulsed Nd:YAG laser fundamental radiation of 1064 nm has facilitated the transformation of bulk graphite (BG) into B-GNSs via liquid carbon phase within 30 min of laser irradiation, and the layer number is are found to be increased with further increase in laser ablation time. The thickness dependent coherent nonlinear optical (NLO) response of the synthesized materials in aqueous dispersion has been determined by spatial self-phase modulation technique. The oxygen-containing surface defects in multilayer GNSs (M-GNSs) have led to scarcity in amount of e-h pairs in compared to that in B-GNSs. Therefore, a better NLO polarization has been observed in B-GNSs in compared to that of M-GNSs. Moreover, the thickness dependent thermal conductivity and hydrodynamic performance of GNSs-water dispersion has led to the observation of tunable NLO response with change in temperature as well as with the intensity of pump laser. The experimental findings obtained in this work may be considered as a key step towards fabrication of graphene from graphitic waste materials for development of future nonlinear photonics devices.
关键词： Waste material,Nonlinear optical properties,Optical properties,Spatial self-phase modulation,Laser ablation,Graphene nanosheets
更新于2025-09-16 10:30:52
-
Simple preparation of graphene quantum dots with controllable surface states from graphite
摘要： Graphite is economic and earth-abundant carbon precursor for preparing graphene quantum dots (GQDs). Here, we report a facile and green approach to produce GQDs from graphite flakes via a pulsed laser ablation (PLA) method assisted by high-power sonication. A homogeneous dispersion of graphite flakes, caused by high-power sonication during PLA, leads to the formation of GQDs following a laser fragmentation in liquid (LFL) rather than laser ablation in liquid (LAL) mechanism. The final product of GQDs exhibits the distinct structural, chemical, and optical properties of pristine graphene itself. However, graphene oxide quantum dots (GOQDs) with abundant surface oxygen-rich functional groups are readily formed from graphite flakes when high-power sonication is not employed during the PLA process. GQDs and GOQDs show a significantly different luminescence nature. Hence, selective production of either functional GQDs or GOQDs can be achieved by simply turning the high-power sonication during the PLA process on and off. We believe that our modified PLA process proposed in this work will further open up facile and simple routes for designing functional carbon materials.
关键词： high-power sonication,graphene quantum dots,luminescence,pulsed laser ablation,graphite flakes
更新于2025-09-16 10:30:52
-
Comparison of combined compression and surgery with high ligation-endovenous laser ablation-foam sclerotherapy with compression alone for active venous leg ulcers
摘要： We aimed to assess the ulcer healing time and recurrence rates after treatment with compression therapy (ct) with or without high ligation-endovenous laser ablation-foam sclerotherapy (HL-eVLA-fS) in people with active venous leg ulcers (VLUs). A retrospective cohort study was conducted with 350 patients with active VLUs treated by compression with or without HL-eVLA-fS in our hospital from 2013 to 2017. The primary outcome was the ulcer healing time; secondary outcomes were the 12-month recurrence rates, the relationship between recurrence and venous reflux, and the complications of the two treatments. In total, 193 patients (200 limbs) underwent compression plus HL-EVLA-FS, and 157 patients (177 limbs) underwent CT alone. The ulcer healing time was shorter in the compression plus HL-EVLA-FS group than in the CT alone group (Hazard Ratio [HR] for ulcer healing, 1.845 [95% CI, 1.474–2.309], P = 0.0001). The 12-month ulcer recurrence rates were significantly reduced in the compression plus HL-EVLA-FS group (HR for ulcer recurrence, 0.418 [95% CI, 0.258–0.677], P = 0.0001). Calf perforator vein reflux (CPVR) and isolated superficial venous reflux (ISVR) were risk factors for ulcer recurrence. the combined operation with ct resulted in faster healing of VLUs, a lower ulcer recurrence rate and lower VcSS values after intervention than ct alone.
关键词： venous leg ulcers,ulcer healing time,high ligation-endovenous laser ablation-foam sclerotherapy,compression therapy,recurrence rates
更新于2025-09-16 10:30:52