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Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process
摘要： Recently developed concentric laser metal wire deposition (LMWD) heads allow metal addition processes which are independent of the deposition direction, thus enabling complex paths to be generated. The sensitivity of the process to height deviations has experimentally been observed to be greater with this type of head than with powder ones, therefore requiring more precise and local process control algorithms to be implemented. This work developed a methodology for measuring the part, layer by layer, using a 3D scanner based on structured laser light. Height corrections were applied to the mean and intra-layer height deviations by recalculating the deposition trajectories of the next layer to be deposited. Local height deviations were adjusted by varying the scanning speed, thus increasing the feed rate in the lower areas and decreasing it in the higher ones. Defects generated in the purpose, with height differences within the layer, were successfully corrected. A flat layer was re-established through the application of the control strategy. The internal integrity of the parts due to the scanning speed variation was analyzed, resulting in fully dense parts. The structured light measurement and height correction systems are found to be an affordable and time-efficient solution that can be integrated into an LMWD environment, thereby improving the process robustness.
关键词： cladding,coaxial wire feed,metal wire,additive manufacturing,monitoring,laser deposition,structured light scanning,height control
更新于2025-11-28 14:24:20
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Research on the “∞”-shaped laser scanning welding process for aluminum alloy
摘要： To solve the problems of poor quality and insu?cient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 mm and 3 mm thick specimens as the research objects, the study of a “∞”-shaped laser scanning welding process was conducted, and the similarities and di?erences between the welding process and that of single pass laser welding were compared. The in?uence of “∞”-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the “∞”-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased signi?cantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense ?sh scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was ?ne and distributed with equiaxed dendrites.
关键词： Weld appearance,Weld performance,Laser technique,“∞”-shaped laser scanning welding,Molten pool characteristics
更新于2025-11-28 14:24:20
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High tension electrocution death: New histopathological cardiac tools by Confocal Laser Scanning Microscope
摘要： In deaths due to electrocution intraepidermal separation, vacuolation of epidermal cells, “swiss cheese” aspect of the superficial part of epidermis (swollen and with multiple vescicles), metallization, necrosis of collagenous fibers, cardiomyocytes alterations are microscopically described. No cardiac nerve damage due to electricity is actually reported in literature. In this work we tried to find new morphological signs in the hearts of deaths due to electrocution. In three cases of deaths due to electrocution, in which forensic autopsies were performed within 36 h of the death, heart specimens were taken at the level of common trunk of the left coronary artery. The myocardium histological examination at optical microscope and Confocal Laser Scanning Microscope (CLSM) revealed fragmentation of cardiomyocytes, nerve trunks damage with hydropic swelling of the nerve fibers, interstitial and sub-nerve-sheath edema, very dishomogenous distribution of the natural fluorescence of the neurofilaments, coarctation of epicardial gangliar cells with cytoplasmic cleft and irregular fluorescence pattern. Identification of S-100 protein by immunohistochemistry can help to better observe the hydropic swelling of the nerve fibers and the central cytoplasmic clefts. These alterations could be used in future as specific signs of the passage of the electrical current through the heart. We recommend heart specimens at the level of common trunk of the left coronary artery in all the cases of suspected electrocution, to better evaluate cardiac nerve trunks damages and alterations.
关键词： Confocal laser scanning microscope (CLSM),Histology,Cardiac nerves,Electrocution,Fluorescence,Heart
更新于2025-11-21 11:20:42
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Development of a high strength Al–Zn–Si–Mg–Cu alloy for selective laser melting
摘要： Despite additive manufacturing processes are already widely used in several industrial applications, there are few materials that are specifically designed and optimized for these technologies. Currently, only few Al alloys are available on the market and employed for 3D printing of structural parts. In particular, SieMg bearing alloys are the most common Al alloys for additive manufacturing, featuring high processability but moderate mechanical properties. By this work, we studied the effect of Si addition on the hot cracking susceptibility of a high strength AleZneMgeCu alloy. A preliminary activity has been carried out by blending AleZneMgeCu and AleSieMg powders and analysing their microstructure and properties achieved after selective laser melting. Eventually a new AleZneSieMgeCu alloy has been designed, produced as powder alloy by gas atomization and tested. The microstructure and phase transformations of the new alloy has been investigated by synchrotron X-ray diffraction, differential scanning calorimetry and microscope analysis. The AleZneSieMgeCu alloy processed by selective laser melting featured a relative density of 99.8%, no hot cracks were noticed within the investigated microstructures. The ability of the new alloy to respond to aging starting from both as built and solution annealed conditions has been also evaluated. A good response to direct aging (directly from as built condition) was demonstrated, featuring yield strength and ultimate tensile strength of 402 and 449 MPa, respectively, and hardness of 174 HV after optimized aging at 165 (cid:1)C for 2 h.
关键词： Differential scanning calorimetry,Metal additive manufacturing,Mechanical properties,Synchrotron X-ray diffraction,High strength Al alloy
更新于2025-11-21 11:18:25
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Color Reproduction Accuracy Promotion of 3D-Printed Surfaces Based on Microscopic Image Analysis
摘要： Full-color 3D printing technology is a powerful process to manufacture intelligent customized colorful objects with improved surface qualities; however, poor surface color optimization methods are the main impeding factors for its commercialization. As such, the paper explored the correlation between microstructure and color reproduction, then an assessment and prediction method of color optimization based on microscopic image analysis was proposed. The experimental models were divided into 24-color plates and 4-color cubes printed by ProJet 860 3D printer, then impregnated according to preset parameters, at last measured by a spectrophotometer and observed using both a digital microscope and a scanning electron microscope. The results revealed that the samples manifested higher saturation and smaller chromatic aberration (ΔE) after post-processing. Moreover, the brightness of the same color surface increased with the increasing soaked surface roughness. Further, reduction in surface roughness, impregnation into surface pores, and enhancement of coating transparency effectively improved the accuracy of color reproduction, which could be verified by the measured values. Finally, the chromatic aberration caused by positioning errors on different faces of the samples was optimized, and the value of ΔE for a black cube was reduced from 8.12 to 0.82, which is undetectable to human eyes.
关键词： Structural characterisation,Impregnating process,Scanning electron microscope,Image analysis,Color optimization,Full-color printing
更新于2025-11-21 11:18:25
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[Methods in Molecular Biology] BCL-2 Family Proteins Volume 1877 (Methods and Protocols) || Quantification of the Interactions Between BCL-2 Proteins by Fluorescence Correlation Spectroscopy
摘要： The proteins of the Bcl-2 family regulate apoptosis by forming a complex interaction network whose output determines whether mitochondrial outer membrane permeabilization is executed. Quanti?cation of complex formation between Bcl-2 proteins in solution and in membranes is therefore key to understand how the hierarchy of interactions controls cell death induction. Fluorescence correlation spectroscopy (FCS) is a noninvasive, nondestructive method to investigate the mobility and the association of ?uorescently labeled biomolecules that has provided useful insight into the binding af?nity of the Bcl-2 interactome. FCS is based on the detection of ?uorescence ?uctuations caused by the diffusion of individual molecules through a very tiny observation volume of the detection system. Scanning FCS (SFCS) solves some of the practical challenges of acquiring FCS in membranes and expands the application scope of the method. In this chapter, we explain the principle of FCS and describe protocols how it can be used to quantify interactions between Bcl-2 proteins in solution and in model membrane systems.
关键词： FCCS,Scanning FCCS,Bcl-xL,cBid,Bcl-2,Fluorescence correlation spectroscopy,FCS,Bax
更新于2025-11-21 11:08:18
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Evaluation of various tissue-clearing techniques for the three-dimensional visualization of liposome distribution in mouse lungs at the alveolar scale
摘要： Purpose: To develop a three-dimensional visualization method for evaluating the distribution of pulmonary drug delivery systems and compare four tissue-clearing techniques (ClearT2, CUBIC, ScaleS, and SeeDB2) using intrapulmonary liposomes as drug carriers. Methods: Rhodamine B-labeled liposomes were administered intrapulmonarily to mice using a MicroSprayer, and then fluorescent-labeled tomato lectin was administered intravenously to visualize the general lung structure. Tissue-clearing treatment of the mouse lungs was performed using the standard protocols of the ClearT2, CUBIC, ScaleS, and SeeDB2 techniques. Lung clearing was clarified using laser-scanning confocal microscopy, and three-dimensional images were reconstructed. Results: Fluorescent-labeled tomato lectin was preserved using ClearT2 and SeeDB2 but not using CUBIC and ScaleS. In addition, the liposomes were stable in ClearT2 reagent, but they were mostly degraded in other reagents by surface-active agents. ClearT2 treatment enabled the three-dimensional visualization of intrapulmonary rhodamine B-labeled liposomes at the alveolar scale. Conclusions: These results suggest that the ClearT2 tissue-clearing technique was appropriate for the three-dimensional visualization of intrapulmonary liposomes at the alveolar scale. This study provides important information for selecting and optimizing suitable optical tissue-clearing techniques in lungs for evaluating the distribution of pulmonary drug delivery systems.
关键词： fluorescence preservation,Intrapulmonary distribution,inhalation,liposomes,drug delivery systems,laser-scanning confocal microscopy
更新于2025-11-21 11:08:12
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3D laser scanning and digital restoration of an archaeological find
摘要： The current paper demonstrates the digital recreation and 3D printing of a missing fragment of an ancient ceramic pottery following digitization using a three dimensional laser scanning. The resulting point-cloud of the laser scans was treated with a series of advanced software for the creation of surfaces and ultimately for a digital model. An analytical methodology is presented revealing the step by step approach, which is an innovative way of recreating a missing fragment. Such approach aims to demonstrate the level of contribution that the ever evolving computer based technologies and 3D printing could bring to cultural heritage. The reverse engineering method presented for the reconstruction of a ceramic pottery, which is a part of the larger field of digital archaeology, is believed to benefit a variety of interested parties including 3D CAD users and designers, archaeologists and museum curators.
关键词： 3D printing,archaeological find,reverse engineering,digital restoration,3D laser scanning
更新于2025-11-21 11:01:37
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Alignment of liquid crystals using Langmuir?Blodgett films of unsymmetrical bent-core liquid crystals
摘要： The properties of the thin films of liquid crystal (LC) molecules can be governed easily by external fields. The anisotropic structure of the LC molecules has a large impact on the electrical and optical properties of the film. The Langmuir monolayer (LM) of LC molecules at the air–water interface is known to exhibit a variety of surface phases which can be transferred onto a solid substrate using the Langmuir?Blodgett (LB) technique. Here, we have studied the LM and LB films of asymmetrically substituted bent-core LC molecules. The morphology of LB film of the molecules is found to be a controlling parameter for aligning bulk LC in the nematic phase. It was found that the LB films of the bent-core molecules possessing defects favour the planar orientation of nematic LC, whereas the LB films with fewer defects show homeotropic alignment. The defect in LB films may introduce splay or bend distortions in the nematic near the alignment layer which can govern the planar alignment of the bulk LC. The uniform layer of LB film facilitates the molecules of nematic to anchor vertically due to a strong van der Waals interaction between the aliphatic chains leading to a homeotropic alignment.
关键词： field emission scanning electron microscope,atomic force microscope,Langmuir?Blodgett film,liquid crystals,Brewster angle microscopy,Langmuir monolayer
更新于2025-11-21 11:01:37
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Building Intermixed Donor-Acceptor Architectures for Water-Processable Organic Photovoltaics
摘要： A modified synthesis method for aqueous nanoparticle printing inks, based upon vacuum-assisted solvent removal, is reported. Poly(3-hexylthiophene) : phenyl C61 butyric acid methyl ester nanoparticle inks were prepared via this modified miniemulsion method; leading to both an improvement in photoactive layer morphology and a substantial reduction in the ink fabrication time. A combination of UV-visible spectroscopy, photoluminescence spectroscopy and scanning transmission X-ray microscopy measurements revealed a nanoparticle morphology comprised of highly intermixed donor-acceptor domains. Consistent with these measurements, dynamic mechanical thermal analysis of the nanoparticles showed a glass transition temperature (Tg) of 104 °C, rather than a pure polymer phase or pure fullerene phase Tg. Together the spectroscopy, microscopy and thermomechanical data indicate that rapid solvent removal generates a more blended nanoparticle morphology. As such, this study highlights a new experimental lever for optimising nanostructure in the photoactive layer of nanoparticulate organic photovoltaic devices by enabling highly intermixed donor-acceptor architectures to be built from customised nanoparticulate inks.
关键词： organic photovoltaic,scanning transmission X-ray microscopy,morphology,colloidal inks,exciton dissociation,Nanostructure,eco-friendly processing
更新于2025-11-19 16:46:39