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Ultrathin Hexagonal PbO Nanosheets Induced by Laser Ablation in Water for Chemically Trapping Surface-Enhanced Raman Spectroscopy Chips and Detection of Trace Gaseous H <sub/>2</sub> S
摘要： Lead oxide (PbO) nanosheets are of significance in design of functional devices. However, facile, green and fast fabrication of ultrathin and homogenous PbO nanosheets with chemically clean surface is still desirable. Herein, a simple and chemically clean route is developed for fabricating such nanosheets via laser ablation of a lead target in water for a short time and then ambient ageing. The obtained PbO nanosheets are (002)-oriented with microsize in planar dimension and ca. 15 nm in thickness. They are mostly hexagonal in shape. Experimental observations of the morphological evolution have revealed that the formation of such PbO nanosheets can be attributed to two processes: (i) laser ablation-induced formation of ultrafine Pb and PbO nanoparticles (NPs); (ii) PbO NPs’ aggregation and their oriented connection growth. Importantly, a composite surface enhanced Raman spectroscopy (SERS) chip is designed and fabricated, by covering a PbO nanosheets’ monolayer on a Au NPs’ film. Such composite SERS chip can be used for the fast and trace detection of gaseous H2S, in which the PbO nanosheets can effectively chemically trap H2S molecules, demonstrating a new application of these PbO nanosheets. The response of this chip to H2S can be detected within 10s and the detection limit is below 1 ppb. Also, this PbO nanosheet-based chip is reusable by heating after use. This study not only deepens understanding the NPs-based formation mechanism of nanosheets, but also provides the renewable SERS-chips for the highly efficient detection of trace gaseous H2S.
关键词： Ultrathin hexagonal PbO nanosheets,Chemically trapping-SERS chip,Trace detection of gaseous H2S,Reusable performance,Laser ablation in water
更新于2025-09-23 15:19:57
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Laser-engineered heavy hydrocarbons: Old materials with new opportunities
摘要： Polycyclic heavy hydrocarbons (HHs) such as coal, tar, and pitch are a family of materials with extremely rich and complex chemistry, representing a massive opportunity for their use in a range of potential applications. The present work shows that optimal selection of initial HHs based on molecular constituents is essential in tuning the material for a particular and targeted electronic application. Combining the selection of feedstock chemistry (H:C and aromatic content) and controlling variable laser treatment parameters (laser power, speed, and focus) lead to full control over the H:C ratio, sp2 concentration, and degree of graphitic stacking order of the products. The broad intertunability of these factors results from a wide distribution of carbon material crystallinity from amorphous to highly graphitic and a broad distribution of electrical conductivity up to 103 S/m.
关键词： heavy hydrocarbons,graphitization,conductivity,electronic applications,laser ablation
更新于2025-09-23 15:19:57
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Dynamic characteristics of multi-charged ions emitted from nanosecond laser produced molybdenum plasmas
摘要： Diagnostics of plasma-wall interaction processes provide important information for nuclear fusion devices. Elucidation of the charge state distribution and temporal evolution of the multi-charged ions is essential to improve laser ablation-based diagnostics of the plasma-wall interaction processes. Molybdenum is a material of interest in fusion and has been used as the plasma-facing material of the first wall in the EAST tokamak. In this work, the dynamic characteristics of multi-charged ions emitted from a molybdenum plasma produced by a Q-switched Nd:YAG nanosecond laser (wavelength 1064 nm, pulse width 7 ns) were studied using time of flight mass spectroscopy under a pressure of 6×10-4 Pa. The charge state distribution and temporal evolution of the multi-charged ions at various laser power densities from 0.85 GW/cm2 to 7.9 GW/cm2 were systematically investigated. This power density range is commensurate to that used in LIBS and LIAS diagnostics of the plasma-wall interaction process in EAST tokamaks.The ion charge state was found to increase with laser power density and the observed maximum charge state was up to seven at the highest laser power density used in these experiments. The higher charged ions had greater velocities indicating that separation took place between the different charged ions during the plasma expansion process. The origin of multi-charged ions is attributed to step-wise ionization due to plasma shielding from strong laser absorption in the plasma and the reduction of the ablation rate with increase in laser power density. The velocities between these multi-charged ions were related to the acceleration of the transient plasma sheath during the laser interaction with the target and plasma.
关键词： molybdenum plasma,plasma-wall interaction,time of flight mass spectroscopy,multi-charged ions,laser ablation
更新于2025-09-23 15:19:57
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Laser Ablation of Abnormal Neurological Tissue Using Robotic NeuroBlate System (LAANTERN): 12-Month Outcomes and Quality of Life After Brain Tumor Ablation
摘要： Laser Ablation of Abnormal Neurological Tissue using Robotic NeuroBlate System (LAANTERN) is an ongoing multicenter prospective NeuroBlate (Monteris Medical) LITT (laser interstitial thermal therapy) registry collecting real-world outcomes and quality-of-life (QoL) data. To compare 12-mo outcomes from all subjects undergoing LITT for intracranial tumors/neoplasms. Demographics, intraprocedural data, adverse events, QoL, hospitalizations, health economics, and survival data are collected; standard data management and monitoring occur. A total of 14 centers enrolled 223 subjects; the median follow-up was 223 d. There were 119 (53.4%) females and 104 (46.6%) males. The median age was 54.3 yr (range 3-86) and 72.6% had at least 1 baseline comorbidity. The median baseline Karnofsky Performance Score (KPS) was 90. Of the ablated tumors, 131 were primary and 92 were metastatic. Most patients with primary tumors had high-grade gliomas (80.9%). Patients with metastatic cancer had recurrence (50.6%) or radiation necrosis (40%). The median postprocedure hospital stay was 33.4 h (12.7-733.4). The 1-yr estimated survival rate was 73%, and this was not impacted by disease etiology. Patient-reported QoL as assessed by the Functional Assessment of Cancer Therapy-Brain was stabilized postprocedure. KPS declined by an average of 5.7 to 10.5 points postprocedure; however, 50.5% had stabilized/improved KPS at 6 mo. There were no significant differences in KPS or QoL between patients with metastatic vs primary tumors. Results from the ongoing LAANTERN registry demonstrate that LITT stabilizes and improves QoL from baseline levels in a malignant brain tumor patient population with high rates of comorbidities. Overall survival was better than anticipated for a real-world registry and comparative to published literature.
关键词： Brain tumor,Laser ablation,Quality of life,LITT,Survival
更新于2025-09-23 15:19:57
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Numerical study on the laser ablative Rayleigha??Taylor instability
摘要： The laser ablative Rayleigh–Taylor instability plays an important role in the ignition of inertial re?nement fusion. An accurate simulation of this process is important to control the growth of ?ow instability during the implosion. In this paper, taking the simulations of the hydrodynamics, the laser energy deposition and the electronic thermal conductivity into consideration, a massively parallel laser ablative Rayleigh–Taylor instability code based on Euler method is developed. Some open source codes are used to improve the code development ef?ciency. The accuracy of the hydrodynamics simulation is tested by an analytical theory about the weakly nonlinear Rayleigh–Taylor instability with double interfaces. The benchmark of an one dimensional heat conductivity is used to test the accuracy of the thermal conductivity simulation. The laser ablative plane target and the laser ablative Rayleigh–Taylor instability are used to test the reliability of the code on the simulation of the whole laser ablative process. It is shown that the con?dence of our numerical simulation code is high and the code framework we designed is effective. It can be a basis on studying the problems about the laser ablative instability in inertial re?nement fusion.
关键词： Rayleigh–Taylor instability,Numerical simulation,Inertial con?nement fusion,Laser ablation
更新于2025-09-23 15:19:57
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Laser ablation of Ni in the presence of external magnetic field: Selection of microsized particles
摘要： The study presents results of nanosecond laser ablation of a Ni target in a liquid as a method of producing contamination-free micro- and nanosized colloidal structures. The ablation was performed in two liquids – double distilled water and ethanol, as their role on the characteristics of the ablated material is clarified. The laser ablation method in liquid was extended by applying an external magnetic field during the ablation process. A separation of micron and submicron particles from the nanoparticles in the colloidal solution is achieved by placing a substrate in the liquid, where the micron size structures are deposited under the action of the external magnetic field. At certain experimental conditions, the deposition of ordered one-dimensional microstructures on the substrate can be realized. The influence of different laser wavelengths on the features of the nanostructures dispersed in the liquid and microstructures deposited on the substrate was also investigated. On the basis of detailed analyses using Optical Microscopy, Scanning Electron Microscopy, Selected area electron diffraction, and Transmission Electron Microscopy the morphology, composition, and size distribution of the fabricated structures were studied. The presented method allows the fabrication of contamination-free micro- and nanostructures with potential applications in biotechnology, catalysis, and magneto-optics devices.
关键词： Laser ablation in liquid,Metal nanoparticles,Microstructures,Colloidal solution,External magnetic field
更新于2025-09-23 15:19:57
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Formation of titanium carbide on the titanium surface using laser ablation in n-heptane and investigating its corrosion resistance
摘要： Laser ablation of titanium in liquid (LAL) using a fiber laser was studied. Firstly, LAL was carried out in toluene, n-hexane, n-heptane, and acetone as liquid media at the same irradiation conditions. Samples were characterized by different diagnostic techniques X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). It was found that titanium carbide (TiC) structure has been generated on the surface of laser ablated samples in toluene, n-hexane, and n-heptane. Also, titanium dioxide was formed on the surface of laser ablated sample in acetone along with TiC. After that, n-heptane was chosen as the adequate liquid medium. LAL process was repeated in n-heptane for different ablation process times at the same irradiation conditions. Samples were investigated by XRD, Raman spectroscopy, EDS, nuclear reaction analysis (NRA), and cross sectional FESEM. It was concluded that the ablation process time of about 30 s is threshold time to form detectable TiC structure by XRD. Additionally, it was deduced that the amount of the carbon (in two forms of amorphous and carbidic) on the surface of the irradiated titanium for about 2 min (S8 sample) is more than other samples. The corrosion behavior of samples was studied by electrochemical impedance spectrometry (EIS) tests. The EIS plots obtained after 24, 48, 72, and 96 h immersion time showed the corrosion resistance of S8 sample enhancement in Ringer's solution compared with the other samples, and the corrosion resistance of this sample increased by rising the immersion time up to 96 h.
关键词： EIS.,titanium carbide,Ringer's solution,n-heptane,laser ablation,titanium
更新于2025-09-19 17:15:36
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A pilot study of the shapes of ablation lesions in the canine prostate by laser, radiofrequency and microwave and their clinical significance
摘要： To explore the shape characteristics of ablation lesions created via laser ablation (LA), radiofrequency ablation (RFA) and microwave ablation (MWA) in canine prostates and the clinical significance of these characteristics, six adult male beagles were randomly assigned to the LA, RFA, and MWA groups. These ablations were performed with common parameters applied in clinical practice (LA, 3 W/1200 J; RFA and MWA, 30 W/120 s). One ablation lesion was created in each lobe of the prostate via the ablation technique, resulting in a total of twelve ablation lesions. Transrectal ultrasound (TRUS) was used as guidance during puncture and to monitor changes in the ablation lesions. Finally, the ablation efficacy was assessed using transrectal contrast-enhanced ultrasonography (CEUS), and the transverse diameter (TRD), anteroposterior diameter (APD) and longitudinal diameter (LD) of each ablation lesion were measured. The volume (V) and the ratio (R) value were calculated. R reflects the shape characteristic of the ablation lesion (the R value close to 1.0 indicates a more spherical shape). The R values of the ablation lesions were 0.89 ± 0.02, 0.72 ± 0.01, and 0.65 ± 0.03 for RFA, MWA and LA, respectively, and they were significantly different (P = 0.027). The volumes of the ablation lesions were 2.17 ± 0.10 ml, 1.51 ± 0.20 ml, and 0.79 ± 0.07 ml for MWA, LA and RFA, respectively, and they were also significantly different (P = 0.001). The three abovementioned thermal ablation techniques with common parameters in clinical practice can be used for ablation in the prostate. The shapes and volumes of the ablation lesions of the three techniques were varied: The RFA-created lesions had the lowest volumes and were more spherical in shape, demonstrating that RFA could be used for the treatment of relatively small lesions or tumours adjacent to vital organs. The MWA lesions had the largest size with a spherical shape, which could be advantageous for the ablation of tumours with relatively large sizes. The sizes of the ablation lesions created via LA were between those of RFA and MWA but presented more oval in shape, suggesting that this method is highly appropriate for the ablation of benign prostatic hyperplasia (BPH).
关键词： canine prostate,ablation lesions,clinical significance,microwave ablation,laser ablation,radiofrequency ablation
更新于2025-09-19 17:13:59
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Study of the physicochemical surface alterations and incubation phenomena induced on iron targets by nanosecond pulsed laser ablation in liquids: Effect on productivity and characteristics of the synthesized nanoscale zero-valent iron (nZVI) particles
摘要： This work presents a systematic study of the significant role of the surface physicochemical alterations produced during the laser ablation of massive iron disks submerged in different solvents on the generation of colloidal iron nanoparticles. For that purpose, the laser ablation thresholds and the incubation coefficients for various pulse numbers per site and pulse energies have been measured under distilled water (DW) and ethanol (EtOH). After that, a complete physicochemical characterization of these targets indicated higher threshold fluence values for the ablation experiments conducted in EtOH than those performed in DW. The threshold fluence values decreased also with the decrease of the pulse overlap for both solvents, being it much more pronounced in EtOH. In addition, the related incubation coefficient showed that the incubation effect is lower for experiments conducted in DW. The characteristics of the synthesized nZVI particles were also a function of the solvent nature and the pulse overlap: laser ablation in DW leaded to iron oxide nanoparticles, whereas core-shell iron nanoparticles were obtained in EtOH. Moreover, high pulse overlap values lead to chemical alterations, resulting in a decrease of the composition homogeneity and a strong increase of the nanoparticle polydispersity.
关键词： Incubation effect,Nanosecond pulsed laser ablation in liquids,Raman spectroscopy,Colloidal nanoscale zero-valent iron particles,Laser ablation threshold,Laser induced-chemical surface alteration
更新于2025-09-19 17:13:59
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Non-Contact Damage Detection under Operational Conditions with Multipoint Laservibrometry
摘要： Scanning laser–Doppler vibrometry (SLDV) can localize and visualize damages in mechanical structures. In order to enable scanning, it is necessary to repeat the vibration. Therefore, this technique is not suited to detect emerging hazards in working machinery that change the vibration behavior. A common technique for such cases is monitoring the vibration excited by machine operation with accelerometers. This technique requires mechanical coupling between sensors and the measurement object, which in?uences the high-frequency vibration responses. However, in the low-frequency range, local damages do not shift resonances or distort operational de?ection shapes (ODS) signi?cantly. These alterations in the vibration behavior are tiny and hard to detect. This paper shows that multipoint laservibrometry (MPV) with laser excitation can measure these e?ects e?ciently, and it further demonstrates that damages in?uence ODSs at frequencies above 20 kHz much stronger than at frequencies below 20 kHz. In addition, ODS-based damage indices are discussed; these are highly sensitive to minute visible changes of the ODSs. In order to enhance the sensitivity of hazard detection, the response vector assurance criterion value is computed and evaluated during operation. The capabilities and limitations of the methodology on the example of a cantilever with manually emerging damage are demonstrated.
关键词： structural health monitoring,multipoint laser-Doppler vibrometer,operational de?ection shape,operational condition,damage detection,laser–Doppler vibrometry,non-destructive testing,laser ablation
更新于2025-09-19 17:13:59