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Cellulose paper support with dual-layered nanoa??microstructures for enhanced plasmonic photothermal heating and solar vapor generation
摘要： Plasmonic nanoparticles, such as gold nanoparticles (AuNPs), have been actively applied in solar vapor generation for seawater desalination and water purification, owing to their photothermal heating performances. Such nanoparticles have been frequently anchored within porous supporting materials to ensure easy handling and water absorption. However, there has been limited progress in improving the transport efficiency of light to nanoparticles within porous supports to achieve more effective photothermal heating. Here, we show an enhanced light absorption of AuNPs by supporting on a cellulose paper with tailored porous structures for efficient photothermal heating. The paper consists of AuNP-anchored cellulose nanofibers and cellulose pulp as the top and bottom layers, respectively, which provides dual-layered porous nano-microstructures in the perpendicular direction. Then, the bottom layer with pulp-derived microstructures reflects the transmitted light back to AuNPs within the top layer, which improves their light absorptivity. Thus, under 1 sun illumination, the dual-layered paper demonstrates superior performance in photothermal heating (increases from 28 °C to 46 °C) and solar vapor generation (1.72 kg m?2 h?1) compared with the single-layered AuNP-anchored cellulose nanofiber paper even at the same AuNP content. Furthermore, the water evaporation rate per AuNP content of the dual-layered paper is more than 2 times higher than those of the state-of-the-art AuNP-anchored porous materials under the same light irradiation. This strategy enables the efficient use of precious plasmonic nanoparticles for further development of solar vapor generation.
关键词： gold nanoparticles,Plasmonic nanoparticles,cellulose paper,nano-microstructures,photothermal heating,solar vapor generation
更新于2025-09-23 15:19:57
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Synthesis, characterization and nanoaggregates of alkyl and triethylene glycol substituted 3,6-carbazolevinylenes homopolymers and block copolymers
摘要： Ring strained carbazolephanedienes containing octyl and triethylene glycol chains have been prepared by the McMurry coupling reaction of their corresponding dialdehydes. A series of well-defined carbazolevinylene homopolymers and block polymers containing octyl and triethylene glycol chains have been synthesized through ring-opening metathesis polymerization of the corresponding carbazolephanedienes using the third generation Grubbs initiator. The optical and electrochemical properties and morphologies of the homopolymers and block copolymers with different block ratios such as 1:1, 3:1 and 1:3 have been investigated. The bandgap of the polymers is relatively low (2.64–2.79 eV) and is strongly dependent on the side chains. The carbazolevinylene block copolymers with higher composition of the triethylene glycol substituted carbazolevinylene block showed sphere-like nanoaggregates due to the highly disorder and flexibility of the triethylene glycol chains. This work demonstrated well control of the polymer microstructures with specific nanoaggregates in solid state.
关键词： Sphere-like nanoaggregates,Carbazolephanedienes,Polymer microstructures,Ring-opening metathesis polymerization,Carbazolevinylene polymers
更新于2025-09-19 17:15:36
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Investigation of Production Limits in Manufacturing Microstructured Surfaces Using Micro Coining
摘要： The application of microstructured surfaces is one possible method to reduce friction in lubricated contacts between components with relative movement. Due to this, the energy efficiency and the occurring wear during the operating time of the final products could be decreased. To manufacture structured surfaces economically, a micro coining process was analyzed within this study. This process offers the potential for integration into the established manufacturing processes of different final products, such as tappets used in a valve train. Thus, large-scale production is enabled. To detect the manufacturing limits of the micro coining process, the manufacturing of the coining tools as well as the coining process needs to be investigated. Within this study, the achievable accuracy and the failure of cuboid and cylindrical microstructure elements with selected dimensions were analyzed. For both types of microstructures, the minimal lateral dimensions were detected. Besides the achievable accuracy, correlations between different geometrical dimensions of the micro elements are presented. Additionally, the aspect ratio is detected as the main cause of failure for the micro coining process. In general, the suitability of a coining process for manufacturing microstructured surfaces is proven.
关键词： geometrical accuracy,microstructures,tribology
更新于2025-09-19 17:15:36
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A strongly hydrophobic and serum-repelling surface composed of CrN films deposited on laser-patterned microstructures that was optimized with an orthogonal experiment
摘要： Owing to frequent contact with blood, the external working medium easily adheres to medical devices such as scalpels and stents, which possibly reduces their performance. To solve this problem and with inspiration from the superhydrophobic and self-cleaning properties of natural lotus leaves, a novel surface composed of laser-patterned (LP) microstructures, with chromium nitride (CrN) films deposited on top, was fabricated on 316 L stainless steel by combining laser patterning and magnetron sputtering. A self-designed circular pattern array was used to generate the LP microstructures. Then, the effects of five key processing parameters, such as the diameter of the circular pattern, spacing of the circular pattern, laser fluence, laser scanning velocity and number of scans, on the wettability of the LP/CrN surface were evaluated using an L16 (45) orthogonal experiment, after which the surface was optimized to further enhance hydrophobicity and serum repellence. The optimized surface strongly corresponded with the Cassie-Baxter model and demonstrated a water (serum) contact angle of 147.7 ± 1.1° (144.2 ± 0.8°) and roll-off angle of 10.8 ± 1.7° (17.1 ± 3.1°), thus showing strongly hydrophobic and serum-repelling characteristics. Moreover, the optimized surface had a weak coffee-stain effect after 60 min of evaporation and exhibited remarkable corrosion resistance in a 3.5 wt% NaCl solution via a potentiodynamic polarization method. This study provides useful insight into the fabrication of a hydrophobic and serum-repelling surface, which can be used to address the problem of blood-adhesion on medical devices.
关键词： Serum repellence,Laser-patterned microstructures,CrN films,Orthogonal experiment,Hydrophobicity
更新于2025-09-19 17:13:59
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Dissipative structure of interaction of laser radiation with construction steel 45
摘要： The article presents the results of a quantitative description of the structure of dissipative structures formed during the interaction of carbon steel 45 with laser radiation, revealing the mechanism of their functioning in a no equilibrium process of interaction of a material with concentrated energy ?ow.
关键词： Heat-affected zone (HAZ),Molten phase zone (MPZ),Solid-phase hardening zone (SPHZ),Microstructures,Tempering zone (TZ)
更新于2025-09-16 10:30:52
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Functional Metallic Microcomponents via Liquid-Phase Multiphoton Direct Laser Writing: A Review
摘要： We present an overview of functional metallic microstructures fabricated via direct laser writing out of the liquid phase. Metallic microstructures often are key components in diverse applications such as, e.g., microelectromechanical systems (MEMS). Since the metallic component’s functionality mostly depends on other components, a technology that enables on-chip fabrication of these metal structures is highly desirable. Direct laser writing via multiphoton absorption is such a fabrication method. In the past, it has mostly been used to fabricate multidimensional polymeric structures. However, during the last few years different groups have put effort into the development of novel photosensitive materials that enable fabrication of metallic—especially gold and silver—microstructures. The results of these efforts are summarized in this review and show that direct laser fabrication of metallic microstructures has reached the level of applicability.
关键词： additive manufacturing,metallic microstructures,direct laser writing
更新于2025-09-12 10:27:22
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A Study of Laser Beam Welding, Gas Tungsten Arc Welding and High Temperature Brazing Processes on Micro hardness and Tensile Strength of AISI Type 316 Stainless Steel
摘要： Thin wall joints for elevated temperature (~550 °C) applications can be prepared by Laser Beam Welding (LBW), Gas Tungsten Arc Welding (GTAW) and High Temperature Brazing (HTB) methods. The joints have been made and tests such as helium leak test (HLT), micro hardness test and tensile test were carried out. A study has been performed on these joining techniques to recognize the suitable method for high temperature applications. No observable leak was identified during HLT. Microstructures shows dissimilarity in solidification morphology due to disparity in heat sources. It has been identified that the joint made by brazing process having higher micro hardness value. Further, it has been observed that LBW joints have better mechanical properties than GTAW joints and HTB joints.
关键词： GTAW,Micro hardness,AISI 316 stainless steels,Tensile properties,High temperature brazing,Microstructures,Nd:YAG Laser
更新于2025-09-12 10:27:22
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Nanosecond laser ablation of the trapezoidal structures for turbomachinery applications
摘要： Correctly designed nature inspired micrometer size grooves i.e. riblets can be used to reduce drag. There exist several methods to manufacture these structures but all of them have their own problems and disadvantages, wherefore they are not perfectly suitable for all real industrial applications. Aim of this paper is to show how a short nanosecond pulse laser ablation can be applied in a micrometer size trapezoidal shape structures i.e. riblets manufacturing for a turbomachinery applications. It is shown that although the quality of the riblets, fabricated with this method, is not as good as with the best possible manufacturing methods, it is still enhancing the properties. Added to this, the processing speed is fast enough and acquisition costs of the system are economic so that method is suitable for the real industrial application. The wind tunnel studies indicate that the fabricated riblets on an airfoil reduce wall shear stress compared to a smooth airfoil without structuring.
关键词： micromachining,nanosecond laser,airfoil,riblet,microstructures,Laser ablation
更新于2025-09-12 10:27:22
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Fabrication of surfaces with reduced friction using nanosecond laser
摘要： In this paper a short i.e. nanosecond pulse laser ablation is utilized to fabricate trapezoidal shaped microstructures i.e. riblets that are known to reduce friction. They can be applied for example in turbomachinery applications to make system more economical by reducing the wall shear stress on flow surfaces. Previously, these structures have been manufactured using different methods like grinding and ultrashort pulse lasers. The methods used before have their disadvantages and therefore they cannot be utilized in all applications. By using the nanosecond pulse laser instead of the shorter pulses, it is possible to manufacture riblets with a high fabrication speed and economically. Although a quality of the nanosecond pulse laser manufactured riblets is not as good as ones fabricated with the ultrashort pulse lasers, they are still able to reduce friction in the turbomachinery application.
关键词： micromachining,tubomachinery,nanosecond laser,airfoil,riblet,laser ablation,microstructures
更新于2025-09-12 10:27:22
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A compact LED-based projection microstereolithography for producing 3D microstructures
摘要： projection microstereolithography (pμSL) is a promising additive manufacturing technique due to its low cost, accuracy, speed, and also the diversity of the materials that it can use. Recently it has shown great potentials in various applications such as microfluidics, tissue engineering, micro-optics, biomedical microdevices, and so on. However, studies on pμSL are still ongoing in terms of the quality and accuracy of the construction process, which particularly affect the fabrication of complex 3D microstructures and make it attractive enough to be considered for commercial applications. in this paper, a compact LeD-based pμSL 3D printer for the fabrication of 3D microstructures was developed, and the effective parameters that influence the quality of construction were thoroughly investigated and optimized. Accordingly, a customized optical system, including illumination optics and projection optics, was designed using optical engineering principles. This custom 3D printer was proposed for the pμSL process, which besides improving the quality of construction, led to the reduction of the size of the device, its cost-effectiveness, and the repeatability of its performance. To demonstrate the performance of the fabricated device, a variety of complex 3D microstructures such as porous, hollow, helical, and self-support microstructures were constructed. in addition, the repeatability of the device was assessed by fabricating microstructure arrays. the device performance showed that the lateral accuracy of printing was better than 5 μm, and the smallest thickness of the printed layer was 1 μm. Moreover, the maximum printable size of the device was 6.4 mm × 4 mm × 40 mm.
关键词： additive manufacturing,projection microstereolithography,optical engineering,microstructures,3D printing
更新于2025-09-12 10:27:22