Abstract ：

Solar interfacial evaporation (SIE) as an emerging green desalination technology has been widely concerned in recent years. However, the interfacial salt fouling associated with evaporation has been limiting the development of this process. The effective separation of salt crystals from interface can avoid the salt fouling and realize resource recovery. Here, we developed a low-cost laser-printing evaporator and enabled salt crystals to drop from the interface autonomously by gravity. The water supply and evaporation capacity of evaporator would affect the location of the crystallization. Interestingly, we proposed a method to predict whether the salt crystals will drop from interface or not. To control the ratio of water supply to evaporation (Qs/Qe) is the critical factor to trigger the salt continuous drop process. This method is also applicable in highly concentrated salt solutions, mixed salt solutions, and salt solutions containing organic matters. This study provides new strategy for the design of salt crystallization recovery systems for solar interfacial evaporators. © 2025 Elsevier B.V.

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Fouling Desalination Salt deposits

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The high optical reflectivity and thermal conductivity of copper make it challenging to form fully dense, high-strength, and high-conductivity copper alloy parts through laser-based additive manufacturing. In this paper, a new method for manufacturing high strength and conductivity copper alloy components by using optical absorption GNSs-coated copper powder and LPBF technology is proposed. The densification behavior, microstructure evolution, mechanical properties, and electrical and thermal conductivity of GNSs/CuCrZr composites prepared by laser powder bed fusion under different process parameters were studied. The high density of 99.58 % was obtained by optimizing the process parameters. With the increase of Ea, the grain size of the cross section is fine and uniform. The columnar grains in the longitudinal section are slender and grow epitaxially along the deposition direction. The yield strength, ultimate tensile strength, and total elongation at break are 220 MPa, 285 MPa, and 30 %, respectively. This is due to the generation of uniformly dispersed and fine precipitates and high-density dislocations. In addition, the interface characteristics and formation mechanism of GNSs/CuCrZr composites were also discussed by first-principles calculations and experimental studies. The interface between GNSs and CuCrZr is well-bonded, and there is a good agreement between the calculated and experimental data. © 2025

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CuCrZr Laser powder bed fusion Microstructure and mechanical properties Graphene nanosheets

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Background: Advanced precision laser technologies for transseptal puncture are still under exploration. Femtosecond lasers, renowned for their high precision and minimal collateral damage, exhibit significant potential in transseptal puncture applications. Objective: This study investigated the feasibility, effectiveness and pathological effects of femtosecond, picosecond, and nanosecond lasers for transseptal puncture in vitro. Methods: Three different pulsed laser systems (femtosecond, picosecond, and nanosecond) were utilized for atrial septal puncture in fresh porcine hearts. The femtosecond laser operated at 1064 nm wavelength with 179 fs pulse width and 500 kHz repetition rate; the picosecond laser at 1962 nm with 52 ps pulse width and 60 MHz repetition rate; and the nanosecond laser at 1064 nm with 70 ns pulse width and 60 kHz repetition rate. With a focused spot size of approximately 100 μm, the power density ranged from 25.50 to 51.00 kW/cm2 (corresponding to energy densities of 0.05–0.10 J/cm2 for femtosecond, 424.40–848.80 μJ/cm2 for picosecond, and 0.42–0.85 J/cm2 for nanosecond lasers). Scanning diameters varied from 0.50 to 3.00 mm at a constant speed of 1 mm/s. Measurements of puncture diameter and thermal damage were taken using a digital optical microscope, with pathological examination evaluating tissue structure and injury extent. Multiple linear regression models were used to evaluate the effects of laser types, power, and scanning diameter on puncture outcomes. P < 0.05 was considered statistically significant. Results: Using a focused spot size of 100 μm at power densities of 25.50–51.00 kW/cm2 (2.0–4.0 W), the femtosecond laser (500 kHz, 0.05–0.10 J/cm2) and picosecond laser (60 MHz, 424.40–848.80 μJ/cm2) achieved complete penetration across 0.50–3.00 mm scanning diameters, with puncture diameters of 0.51–3.02 mm and 0.51–3.01 mm respectively. The nanosecond laser (60 kHz, 0.42–0.85 J/cm2) penetrated only at 0.50 mm scanning diameter and partially at 1.00 mm (3 W–4 W), with significantly smaller diameters (P < 0.001). Multiple regression showed scanning diameter primarily determined puncture size (β = 0.992, P < 0.001), while both power (β = 1.798, P = 0.002) and scanning diameter (β = 2.604, P < 0.001) affected thermal damage, with nanosecond (β = 6.515, P = 0.017) and picosecond lasers (β = 5.595, P = 0.039) showing greater thermal effects than femtosecond laser. Histologically, thermal damage progressed from minimal carbonization at 2 W to moderate-severe eosinophilic degeneration at 4 W… Conclusions: Transseptal puncture using laser systems demonstrated feasibility, particularly with femtosecond laser showing favorable outcomes in precision and thermal control under specified parameters, exhibit significant clinical potential. Further studies are needed to investigate the underlying mechanisms. Key messages: What is already known about this subject? Femtosecond lasers, characterized by their high peak power and minimal thermal damage, are expected to have potential clinical applications in transseptal puncture techniques. What does this study add? The effects of femtosecond, picosecond, and nanosecond lasers on ex vivo porcine atrial septum puncture were studied at varying power levels and puncture diameters. The results showed that femtosecond lasers had superior puncture capabilities compared to nanosecond lasers, with significantly higher thermal damage observed in the nanosecond laser. How might this impact on clinical practice? Ex vivo experiments with advanced lasers, particularly femtosecond lasers, have shown promising clinical feasibility. We will plan to pursue further research based on current findings. © 2024

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In vitro study Transseptal puncture Thermal damage Femtosecond laser

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Laser-induced plasma during the laser lift-off (LLO) process has complex dynamic driving evolution behaviour, presenting a challenge in achieving non-destructive μ-LED transfer. This study systematically explores the mechanism of homogeneous mechanical effect by confined plasma superfluid reflection for lossless μ-LEDs transfer. The stress field distribution of μ-LEDs subjected to the transfer process is simulated from the transferred μ-LED crack morphology, confirming that the non-uniform stress concentration points caused by the plasma evolution process are the main cause of μ-LED breakage. The confined plasma is modelled using the Fock-Plank electron density theory combined with the electrostatic sphere shell model and real-time ICCD imaging, resulting in the characteristic law of the plasma in a confined region over time. The results show that the plasma expansion velocity and the geometry of the interface cavity can be synchronously adjusted by modulating the laser irradiation behaviour, thus realizing its critical Mach number to achieve the plasma conversion from regular reflection to Mach reflection. Based on modulating of superfluid reflection effect, the plasma stress field is effectively homogenized, inducing a damage-free transfer of μ-LEDs. This study provides a novel understanding of plasma dynamics in the picosecond laser transfer process and lays the groundwork for achieving high-quality, non-destructive μ-LED transfers. © 2025 Elsevier B.V.

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Plasma Micro-LED Laser transfer Picosecond laser

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This study investigates the corrosion resistance and protective mechanisms of laser-clad Al2O3-doped Inconel 625 coatings under high-temperature acidic conditions. Inconel 625-xAl2O3 coatings were fabricated via laser cladding and tested in high-temperature acidic environments simulating pipeline conditions. Corrosion media included HCl, H2SO4, HF, HBr (pH=3), and their 1:1:1:1 mixed acid. High-temperature cyclic titration was employed for corrosion testing, while XRD, SEM, EDS, and laser confocal microscopy were used to analyze microstructure, composition, and corrosion products. Results show that increasing Al2O3 content significantly enhances corrosion resistance, reducing rates by 57.9 % in HCl and 46.4 % in HF. Al2O3 forms a stable protective layer, acting as a physical barrier and inhibiting grain growth. A dual-layer oxide film (Al2O3 and Cr2O3) effectively blocks corrosive substance diffusion, further enhancing protection. This study elucidates the pivotal role of Al2O3 in improving the corrosion resistance of Inconel 625 coatings and offers novel insights for the development of high-performance protective coatings tailored for extreme environments.

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Laser cladding Inconel 625 coating High-temperature acidic corrosion

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This study employed the laser in-situ post-weld heat treatment process to achieve in-situ precipitation of carbides (IPC) in the hydrogen embrittlement (HE) sensitive zone of QP980 steels laser welded joints. In the original joint with hydrogen pre-charging, cleavage fracture occurred at the inter-critical heat affected zone (ICHAZ). The IPC process only caused carbides to precipitate in martensite of the ICHAZ. The IPC joint with hydrogen pre-charging (5 min) exhibited ductile fracture at the base material during the slow strain rate tensile test, and the total elongation HE sensitivity of the joint was reduced from 84.6 % to 13.7 %. © 2025 Elsevier Ltd

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Laser beam welding Tensile testing Heat affected zone Hydrogen embrittlement Zone melting Laser heating Textures Ductile fracture

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TA15 alloy, widely utilized in the aerospace industry for its exceptional mechanical properties, was examined in this study for its anisotropic microstructure evolution and deformation behavior in laser melting deposition (LMD)-fabricated samples at room temperature. Specimens were extracted from build (Z-) and scanning (X-) directions and their microstructures and mechanical properties were compared. A method based on in-situ electron back scattered diffraction (EBSD) tensile testing, was used by inserting a tensile stage into scanning electron microscopy (SEM) to observe the real-time microstructure evolution with the change of dynamic tensile force. The evolution of slip bands, grain rotation, grain-to-grain misorientation, and the dynamic change of mechanical properties were also systematically investigated. The results demonstrated that the anisotropic mechanical properties along the Z-and X-directions in LMD-fabricated TA15 alloy stemmed from variations in microstructural anisotropy. Z-direction specimen exhibits high elongation and reduction of cross section, whereas, high tensile strength and yield strength were identified in X-direction. Furthermore, the texture behavior, crack propagation and fracture mechanism are discussed for each specimen orientation.

Keyword ：

TA15 alloy In-situ tensile Laser melting deposition Anisotropic mechanical behavior Texture evolution

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Traditional top-emitting vertical-cavity surface-emitting lasers (VCSELs) exhibit a long distance between the source region and heat sink, and internal heat conduction of the device is difficult, resulting in limited output power of both single-tube and array devices. To address these limitations, this study proposes a top-emitting VCSEL with a heat dissipation hole on the substrate. This hole is located directly below the countertop and is filled with high-thermal-conductivity materials, enabling rapid heat transfer from within the device. This design ensures mechanical support for the entire structure while improving the heat dissipation capacity. Simulation results indicate that the thermal flip power of the VCSEL device with a heat dissipation hole is 9. 54 mW, representing a 36. 4% increase compared to VCSEL devices without a heat dissipation hole. VCSEL devices with an oxidation aperture of 12 μm are prepared and tested under a duty cycle of 0. 6%. The peak power of the VCSEL with a heat dissipation hole reaches 9. 59 mW, which is 31% higher than that of the VCSEL without a heat dissipation hole. © 2025 Universitat zu Koln. All rights reserved.

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high temperature vertical cavity surface emitting laser substrate heat dissipation top emitting

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The preparation of high density Al7000 series Al alloys by laser powder bed fusion (LPBF) is challenging. In this work, a completely crack-free Al–Zn–Mg–Cu–Er–Zr alloy was successfully processed by LPBF. The effect of different laser power and scanning speed on the printability of the alloy was investigated, and the processing window was optimized. By characterizing the microstructure and mechanical properties of the alloy with a density of 99.8 %, it is found that microstructure structure consisting of equiaxed grains at the boundary of the melt pool and columnar grains inside the melt pool. Er and Zr elements participate in the formation of equiaxial grains in the form of Al3Er, Al3Zr and Al3(Er,Zr) phases, which play an important role in inhibiting the epitaxial growth of columnar grains. The as-built alloy achieved an elongation of 17%, with yield strength and ultimate tensile strength of 310 MPa and 368 MPa, respectively. © 2025 The Authors

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Al–Zn–Mg–Cu–Er–Zr alloy Hot cracking Mechanical properties Microstructure Laser powder bed fusion

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Silicon is considered to be the most promising next-generation negative electrode material for LIBs due to its high energy density. However, volume changes of silicon have been a bottleneck limiting their application. A 'sandwich' structured silicon-carbon composite electrode is designed and fabricated to investigate the impact of this design and surface treatment on battery performance. After 300 cycles, the remaining reversible specific capacity of the 'sandwich' structured electrode stabilized at 1350 mAh g−1. Compared to the original nano‑silicon electrode cycled under the same conditions (959 mAh g−1), the capacity increase is 40.7 %, demonstrating the potential of the 'sandwich' silicon anode to enhance battery capacity. Furthermore, different femtosecond laser surface treatments are applied to the 'sandwich' silicon anode. The electrode treated with a linear femtosecond laser exhibits improved rate performance, achieving a higher remaining reversible specific capacity (up to 2050 mAh g−1, with a capacity increase of 113.7 %). The excellent electrochemical performance of the linear laser-treated 'sandwich' silicon anode can be attributed to a more stable mechanical structure (no apparent cracks on the electrode surface after 300 cycles) and higher efficiency in ion/electron conductivity (lower charge transfer impedance Rct and SEI film impedance Rsei values). The proposed design and treatment methods for the anode of lithium-ion batteries provide a pathway and approach for the development of high-capacity lithium-ion battery. © 2025

Keyword ：

Carbon silicon carbide composites Carbon electrodes Femtosecond lasers Carbon carbon composites Lithium-ion batteries Electrochemical electrodes Anodes

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