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US-guided laser treatment of parathyroid adenomas
摘要： Objective: To determine the clinical efficacy of laser ablation for the treatment of primary hyperparathyroidism (pHPT). Materials and methods: Twelve patients with pHPT were treated with laser ablation. Energy was administered by means of 1.5 m optical fibers percutaneously placed into the target via 21 G needles. A laser ablation unit (EchoLaser X4, Esaote) applied 3 W power for 400–600 s/fiber/insertion to a total 3600–9000 Joules of energy. Patient serum parathyroid hormone (PTH) and calcium levels were checked at baseline and thereafter every 6 months. Patients were followed-up for 2 years with serologic and contrast-enhanced ultrasound. Therapeutic success was defined as normal PTH and calcium levels together with disappearance of nodule-related symptoms. Results: All procedures were performed in single session. Immediately following ablation, contrast enhanced ultrasound confirmed that all but one target had become avascular (technical success rate 11/12; 92%), remaining avascular at all follow-up ultrasound examinations, thereafter. The mean volume of parathyroid nodules decreased from 0.54 cc to 0.36 cc (72.0%). Serum PTH and calcium levels were significantly lower at 1, 12 and 24 m compared to baseline (p < 0.01). By 6 m, PTH and calcium returned to normal and were stable until 24 m in all successfully treated patients. All cases of hyperparathyroid-related symptoms resolved by 6 m (ostealgia [n ? 5], repeated renal colic [n ? 5], vomiting [n ? 3]). Only one patient (8%) reported transient dysphonia as a minor complication. Conclusion: Laser ablation of enlarged, symptomatic parathyroid glands is safe and well-tolerated and can produce long-term, sustained reduction of serum PTH and calcium levels.
关键词： primary hyperparathyroidism,parathyroid adenoma,parathyroid ablation,Laser ablation
更新于2025-09-23 15:19:57
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Hyperfine structures and isotopic shifts of uranium transitions using tunable laser spectroscopy of laser ablation plumes
摘要： We report isotopic shifts and hyperfine structures of selected U transitions employing tunable spectroscopy viz: laser-induced fluorescence and laser absorption spectroscopy of laser ablation plumes. The plasmas were produced during ns laser ablation on a natural U metal target which contains 0.73% 235U. Our results show that isotopic shifts between 238U and 235U are entangled with hyperfine structures of 235U. Measurements obtained using laser-induced fluorescence are affected by the high absorbance of 238U. Time-resolved laser absorption spectroscopy is carried out for evaluating the optical absorption and estimating the hyperfine constants.
关键词： LIBS,Hyperfine structure,Laser absorption spectroscopy,Isotopic analysis,Uranium,Laser-induced fluorescence,Laser ablation,Tunable laser spectroscopy
更新于2025-09-23 15:19:57
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Laser-generated plasmas in length scales relevant for thin film growth and processing: simulation and experiment
摘要： In pulsed laser deposition, thin film growth is mediated by a laser-generated plasma, whose properties are critical for controlling the film microstructure. The advent of 2D materials has renewed the interest in how this ablation plasma can be used to manipulate the growth and processing of atomically thin systems. For such purpose, a quantitative understanding of the density, charge state, and kinetic energy of plasma constituents is needed at the location where they contribute to materials processes. Here, we study laser-induced plasmas over expansion distances of several centimeters from the ablation target, which is the relevant length scale for materials growth and modification. The study is enabled by a fast implementation of a laser ablation/plasma expansion model using an adaptive Cartesian mesh solver. Simulation outcomes for KrF excimer laser ablation of Cu are compared with Langmuir probe and optical emission spectroscopy measurements. Simulation predictions for the plasma-shielding threshold, the ionization state of species in the plasma, and the kinetic energy of ions, are in good correspondence with experimental data. For laser fluences of 1–4 J cm?2, the plume is dominated by Cu0, with small concentrations of Cu+ and electrons at the expansion front. Higher laser fluences (e.g. 7 J cm?2) lead to a Cu+ -rich plasma, with a fully ionized leading edge where Cu2+ is the dominant species. In both regimes, simulations indicate the presence of a low-density, high-temperature plasma expansion front with a high degree of ionization that may play a significant role in doping, annealing, and kinetically-driven phase transformations in 2D materials.
关键词： pulsed laser deposition,plasma diagnostics,plasma processing of 2D materials,laser plasma simulation,2D materials,laser ablation,plasma assisted processing
更新于2025-09-23 15:19:57
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Laser ablation and structuring of CdZnTe with femtosecond laser pulses
摘要： We report an experimental investigation on laser ablation and associated surface structuring of CdZnTe by femtosecond Ti:Sa laser pulses (laser wavelength λ～800 nm, ～35 fs, 10 Hz), in air. By exploiting different static irradiation conditions, the fluence threshold and the incubation effect in CdZnTe are estimated. Interestingly, surface treatment with a low laser fluence (laser pulse energy E～5-10 μJ) and number of shots (5≤ N ≤50) show the formation of well-defined cracks in the central part of the shallow crater, which is likely associated to a different thermal expansion coefficients of Te inclusions and matrix during the sample heating and cooling processes ensuing femtosecond laser irradiation. Irradiation with a larger number of pulses (N～500, 1000) with higher pulse energies (E～30-50 μJ) results in the formation of well-defined laser-induced periodic surface structures (LIPSS) in the outskirts of the main crater, where the local fluence is well below the material ablation threshold. Both low spatial frequency and high spatial frequency LIPSS perpendicular to the laser polarization are found together and separately depending on the irradiation condition. These are ascribed to a process of progressive aggregation of randomly distributed nanoparticles produced during laser ablation of the deep crater in the region of the target irradiated by a fluence below the ablation threshold with many laser pulses.
关键词： Laser ablation,CdZnTe,Femtosecond laser surface processing,Laser induced periodic surface structures
更新于2025-09-23 15:19:57
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Optimization of Measuring Parameters for Two-dimensional Elemental Mapping in Laser-induced Breakdown Optical Emission Spectrometry Using 1-kHz Q-switched Nd:YAG Laser
摘要： This paper described how the lateral resolution of an elemental mapping was estimated in laser-induced breakdown optical emission spectrometry (LIBS), when the focus point of a high-frequency Q-switched Nd:YAG laser was moved on a sample surface, along with measuring the emission signal from the resultant plasma. Several measuring parameters were optimized to improve the lateral resolution; namely, they were an averaged laser power of 1 mJ/pulse, a laser repetition frequency of 1 kHz, a scanning rate of the laser beam of 0.5 mm/s, and an atmospheric gas pressure of He 1 000 Pa. Using these optimal parameters, a lateral resolution was obtained to be ca. 20 μm in the one-dimensional direction of laser scan. Furthermore, two model samples, in which regularly-aligned copper circles were deposited on a nickel plate, were irradiated by a scanning laser beam to determine actual resolving abilities both in a line direction along travelling the laser and in a two-dimensional direction over a certain sample area. The sample having an interval of 85 μm between the copper circles could give an emission image which was appropriately resolved in the two-dimensional as well as the one-dimensional direction; however, in the other sample having the 25-μm interval, the two-dimensional resolution became degraded compared to the resolution of the line scan, probably because the ablation grooves, which were left on the sample surface, had a width of more than 100 μm and were overlapped with each other in the observed area.
关键词： lateral resolution,copper,scanning laser beam,laser-induced breakdown plasma spectrometry,laser ablation
更新于2025-09-23 15:19:57
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The Influence of Laser Ablation Parameters on the Holes Structure of Laser Manufactured Graphene Paper Microsieves
摘要： The graphene paper microsieves can be applied in the ?ltration of biological ?uids or separation of solid particles from exploitation ?uids. To produce graphene paper microsieves for speci?c applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 μJ, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (≥10 μm), optimum parameters of graphene paper laser ablation were de?ned using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre–Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of di?raction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed.
关键词： laser manufacturing,graphene paper,picosecond laser,graphene paper microsieves,laser ablation
更新于2025-09-23 15:19:57
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Manipulation of the Size and Phase Composition of Yttrium Iron Garnet Nanoparticles by Pulsed Laser Post-Processing in Liquid
摘要： Modi?cation of the size and phase composition of magnetic oxide nanomaterials dispersed in liquids by laser synthesis and processing of colloids has high implications for applications in biomedicine, catalysis and for nanoparticle-polymer composites. Controlling these properties for ternary oxides, however, is challenging with typical additives like salts and ligands and can lead to unwanted byproducts and various phases. In our study, we demonstrate how additive-free pulsed laser post-processing (LPP) of colloidal yttrium iron oxide nanoparticles using high repetition rates and power at 355 nm laser wavelength can be used for phase transformation and phase puri?cation of the garnet structure by variation of the laser ?uence as well as the applied energy dose. Furthermore, LPP allows particle size modi?cation between 5 nm (ps laser) and 20 nm (ns laser) and signi?cant increase of the monodispersity. Resulting colloidal nanoparticles are investigated regarding their size, structure and temperature-dependent magnetic properties.
关键词： laser melting,yttrium iron oxide,monodisperse,laser fragmentation,phase transformation,garnet,perovskite,laser ablation,ferrimagnetic nanoparticles
更新于2025-09-23 15:19:57
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Preparation and characterization of carbon nanotubes by pulsed laser ablation in water for optoelectronic application
摘要： In the present work, preparation of multi-walled carbon nanotubes (MWCNTs) and carbon nanoparticles (CNPs) by using pulsed laser ablation of a graphite target in water without using catalyst was demonstrated. The effect of laser wavelength on the optical absorption and structural properties has been studied. X-ray diffraction (XRD) data shows the synthesized CNTs were polycrystalline and a peak related to the diamond structure was observed. Scanning electron microscope (SEM) investigation displays that the average diameter of CNTs synthesized with 532 nm was 20 nm and few micrometers in length, while the CNTs synthesized with 1064 nm have an average diameter of 75 nm and lengths of few sub-micrometers. Some of CNPs were noticed to deposit on the CNTs. Transmission electron microscope (TEM) was used to study the morphology of MWCNTs. Raman spectra confirm formation of MWCNTs during the presence of three peaks belonged to D-band, G-band and 2D-band. The intensity ratio of IG/ID is larger than unity for MWCTs prepared by two laser wavelengths. The colloidal MWCNTs prepared by 532 nm laser pulses showed higher absorption than that of MWCNTs prepared with 1064 nm. The current-voltage characteristics and responsivity of hybrid In/p-MWCNTs/n-Si heterojunction photodetectors prepared at different CNTs film thicknesses were investigated at room temperature. The responsivity of hybrid MWCNTs/n-Si photodetector has two peaks of response, the first peak was found at 650 nm and the second peak located at 850 nm. The maximum responsivity was 0.53 A/W at 532 nm was found for the photodetector fabricated with 532 nm laser. The energy band diagram of MWCNTs/Si heterojunction was constructed under illumination condition.
关键词： Hybrid photodetector,CNTs,Laser ablation,CNTs thickness,Laser wavelength
更新于2025-09-23 15:19:57
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Optical control of layered nanomaterial generation by pulsed-laser ablation in liquids
摘要： Pulsed-laser ablation in liquids capitalizes on combining chemical and optical control to rapidly generate size, composition, and phase-controlled nanostructures, without the need for surfactants. Very high temperatures, which we determined to be ca. (8,400 ± 1,300) K, pressures, and ion densities exist in the laser-induced liquid-confined plasma. These unique conditions, coupled with the rapid cooling during which nanoparticles are formed, permitted access to new extreme regions of materials’ phase diagrams. This way, we produced metastable layered copper and zinc hydroxide-based nanocrystals with interesting physical properties that can serve as precursors for two-dimensional inorganic semiconductor nanomaterials.
关键词： LTE spectra,optical control,electron temperature,layered nanocrystals,Pulsed-laser ablation in liquids,laser-induced plasma
更新于2025-09-23 15:19:57
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Detecting Laser-Volatilized Salts with a Miniature 100-GHz Spectrometer
摘要： Rotational transitions are unique identi?ers of molecular species, including isotopologues. This article describes the rotational detections of two laser-volatilized salts, NaCl and KCl, made with a miniature Fourier transform millimeter-wave (FTmmW) cavity spectrometer that could one day be used to measure solid composition in the ?eld or in space. The two salts are relevant targets for icy moons in the outer solar system, and in principle, other molecular solids could be analyzed with the FTmmW instrument. By coupling the spectrometer to a collisionally cooling laser ablation source, (a) we demonstrate that the FTmmW instrument is sensitive enough to detect ablation products, and (b) we use the small size of the FTmmW cavity to measure ablation product signal along the carrier gas beam. We ?nd that for 532 nm nanosecond pulses, ablated molecules are widely dispersed in the carrier-gas jet. In addition to the miniature spectrometer results, we present several complementary measurements intended to characterize the laser ablation process. For pulse energies between 10 and 30 mJ, the ablation product yield increases linearly, reaching approximately 1012 salt molecules per 30 mJ pulse. Using mass spectrometry, we observe Li+, Na+, and K+ in the plumes of ablated NaCl, KCl, and LiCl, which implies dissociation of the volatilized material. We do not observe salt ions (e.g., NaCl+). However, with 800 nm femtosecond laser pulses, the triatomic ion clusters Li2Cl+, Na2Cl+, and K2Cl+ are produced. Finally, we observe incomplete volatilization with the nanosecond pulses: some of the ejecta are liquid droplets. The insights about ablation plume physics gleaned from these experiments should guide future implementations of the laser-volatilization technique.
关键词： KCl,Fourier transform millimeter-wave,FTmmW,rotational transitions,NaCl,mass spectrometry,outer solar system,icy moons,laser-volatilized salts,laser ablation
更新于2025-09-23 15:19:57