Additive manufacturing最新文献

{"title":"Mechanism of grain boundary angle on solidification cracking in directed energy deposition Hastelloy X superalloys","authors":"","doi":"10.1016/j.addma.2024.104406","DOIUrl":"10.1016/j.addma.2024.104406","url":null,"abstract":"<div><p>Solidification cracking occurs only when the grain boundary (GB) angle (<span><math><mi>θ</mi></math></span>) exceeds a critical value. This value, known as the critical cracked GB angle (<span><math><msup><mrow><mi>θ</mi></mrow><mrow><mo>*</mo></mrow></msup></math></span>), can be predicted from the grain coalescence theory based on GB-angle-dependent GB energy. However, the calculated value (<span><math><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>*</mo></mrow></msubsup></math></span>) is always less than the measured value in experiments (<span><math><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>e</mi></mrow><mrow><mo>*</mo></mrow></msubsup></math></span>), which is also confirmed in our directed energy deposition Hastelloy X superalloys. In addition to GB energy, there are evidences showing that GB angle can affect cracking by changing dendrite spacings. We show by experiments and phase field simulations that, same as GB energy, the dendrite spacings at GBs increase with GB angle, but its effect on solidification cracking sensitivity (SCS) is opposite to GB energy. Depending on their relative contributions, three ranges can be identified. In the first range of <span><math><mrow><mi>θ</mi><mo>&lt;</mo><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>*</mo></mrow></msubsup></mrow></math></span>, both dendrite spacings and GB energy have negligible effects on dendrite coalescence, compared to the case inside a grain. In the second range of <span><math><mrow><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>*</mo></mrow></msubsup><mo>&lt;</mo><mi>θ</mi><mo>&lt;</mo><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>e</mi></mrow><mrow><mo>*</mo></mrow></msubsup></mrow></math></span>, dendrite spacings counteract the effect of high GB energy on SCS. It is exactly this effect that induces the gap in <span><math><msup><mrow><mi>θ</mi></mrow><mrow><mo>*</mo></mrow></msup></math></span> between theory and experiments. In the third range of <span><math><mrow><mi>θ</mi><mo>&gt;</mo><msubsup><mrow><mi>θ</mi></mrow><mrow><mi>e</mi></mrow><mrow><mo>*</mo></mrow></msubsup></mrow></math></span>, GB energy plays a dominant role and leads to severe solidification cracking. After including the effect of dendrite spacings on SCS, we predict <span><math><msup><mrow><mi>θ</mi></mrow><mrow><mo>*</mo></mrow></msup></math></span>=15° in directed energy deposition Hastelloy X superalloys, close to the experimental value of 18°. These new findings provide new insights for suppressing cracking by controlling the dendrite spacings near GBs.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142149601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel strengthening mechanism of laser powder bed fusion-manufactured Inconel 718: Effects of customized hierarchical interfaces","authors":"","doi":"10.1016/j.addma.2024.104412","DOIUrl":"10.1016/j.addma.2024.104412","url":null,"abstract":"<div><p>A novel strengthening mechanism involving hierarchical interfaces self-assembled and/or artificially introduced into Inconel 718 (IN718) via laser powder bed fusion (PBF-LB/M) additive manufacturing (AM) has been discovered for the first time. The structures processed by applying two different scanning directions depending on the region have customized hierarchical interfaces that are formed by self-organization of the microscale lamellar structure comprising distinctively different crystal orientations and artificial control of local texture for mesoscale building blocks. The underlying mechanism of strengthening of the structures is clarified using experimental and numerical approaches. Numerical crystal plasticity finite element analysis successfully reproduces the experimental deformation behavior, including the stress-strain curves and anisotropic changes in the shape of the structures, revealing improvements in the mechanical properties by mechanical interaction owing to plastic anisotropy of the lamellar structure. A systematic numerical analysis of the deformation behavior of structures with a higher density of mesoscale interfaces between regions with different local textures suggests possible improvements in the mechanical properties, showing a 13 % increase in 0.2 % proof stress in the optimum structure. Additionally, excellent peak mechanical properties are observed owing to the competition of mechanical interactions between regions with different local textures and a decrease in plastic anisotropy owing to the activation of additional slip modes of the lamellar structure.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214860424004585/pdfft?md5=7226b1c38a2ca82c37bf6340e7d68974&pid=1-s2.0-S2214860424004585-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plant oil body as an effective improver for surimi-based 3D printing","authors":"","doi":"10.1016/j.addma.2024.104422","DOIUrl":"10.1016/j.addma.2024.104422","url":null,"abstract":"<div><p>Plant oil body (POB) is a natural oil droplet in micron- or submicron-scale covered by a specific shell composed of proteins and phospholipids, it has arisen numerous research interests in food industry due to its excellent emulsifying ability and great safety as natural product. In this study, POB has been exploited as an effective textural enhancer in surimi-based 3D food printing, and the underpinned mechanisms were investigated. First, POB with great rheological and emulsifying properties was prepared from peanuts, which behaved as a high internal phase emulsion. Second, for the first time, POB was introduced into surimi-based inks, which was able to facilitate the rearrangement of myofibrillar proteins through emulsification, thus ensuring fidelity and stability of 3D-printed surimi structures. The best printing performance was achieved at 2 % POB addition without compromising the surimi gel properties. However, excessive POB addition resulted in decreased viscosity, printing failure, and deteriorated gel characteristics. Third, a new mechanism was proposed to elucidate the interaction between POB and surimi proteins. On the one hand, POB physically filled in the gaps between proteins to increase the continuity and integrity of the surimi inks, thus improving the printability. On the other hand, POB with active surface altered the surimi protein molecular structure to boost the formation of hydrophobic interactions and disulfide bonds, leading to improved gel properties. Overall, this study demonstrated that POB was an effective improver for surimi-based 3D printing, providing new insights on developing new application of POB in food industry.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142242546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypereutectic Al-Ce-X (X=Mn, Cr, V, Mo, W) alloys fabricated by laser powder-bed fusion","authors":"","doi":"10.1016/j.addma.2024.104442","DOIUrl":"10.1016/j.addma.2024.104442","url":null,"abstract":"<div><div>We characterize the microstructures and high-temperature mechanical properties of Al-2Ce and ternary Al-2Ce-1X (at.%) alloys fabricated by laser powder-bed fusion (LPBF), where X = Mn, Cr, V, Mo, and W are slow-diffusing transition metals. All ternary alloys show a hypereutectic microstructure in the as-LPBF state, containing an interconnected network of eutectic Al₁₁Ce₃ phases (∼10 vol.%) and an additional population of submicron, equiaxed Al₂₀CeX₂ primary precipitates (∼10 vol.%) which are isomorphous among these five alloys. Similar microstructures are present in arc-melted rods and atomized powders but are coarser due to the slower cooling rates in these processes. The hardness of the as-LPBF ternary Al-Ce-X alloys (1300–1400 MPa) is higher than that of the binary Al-Ce alloy (∼1100 MPa) due to the higher volume fraction of strengthening phases. Furthermore, during exposure at 400 °C for up to three months, greater hardness retention is achieved in the ternary Al-Ce-X alloys (65–75%) than in the binary Al-Ce alloy (∼55%), which is attributed to the extreme coarsening resistance of the Al₂₀CeX₂ precipitates imparted by the very slow-diffusing ternary solute. These coarsening-resistant Al₂₀CeX₂ precipitates also substantially improve alloy creep resistance, increasing the threshold stress for dislocation creep at 300°C from ∼32 MPa for the binary Al-Ce alloy to ∼77–100 MPa for the ternary Al-Ce-X alloys, and at 400°C from &lt;10 MPa for the binary Al-Ce alloy to &gt;40 MPa for the ternary Al-Ce-V alloy.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure-reinforced periodic porous piezoceramics for ultrahigh electromechanical response manufactured by vat photopolymerization","authors":"","doi":"10.1016/j.addma.2024.104446","DOIUrl":"10.1016/j.addma.2024.104446","url":null,"abstract":"<div><div>Traditionally, it is accepted that the lower permittivity of porous piezoceramics contributes to a high <strong>piezoelectric voltage coefficient</strong>(g₃₃). However, this enhancement is not evident due to the insufficient polarization and inefficient stress transfer in porous piezoceramics with random and irregular pores. Herein, Gyroid structures with triply periodic minimum surface lattices are introduced into the fabrication of porous piezoceramics by vat photopolymerization technology. Based on experimental and simulation data, porous piezoceramics need to be subjected to higher electric fields (5 kV/mm) to achieve a fuller polarization, whereas the Gyroid structure has stable and excellent resistance to electrical breakdowns. Meanwhile, the increase in the average stress and the effective stress transfer in the Gyroid structure offset the negative effect of the decrease in the piezo-phase on the piezoelectric properties. Ultimately, d₃₃ remained unexpectedly stable and are essentially the same value as in the bulk ceramics during the increase in porosity from 55 <em>vol.</em>% to 75 <em>vol.</em>%. Expectedly, due to the significant reduction of the dielectric constant, an ultrahigh g₃₃ value up to 89 mV∙m/N is achieving in 75 <em>vol.</em>% porosity porous ceramics, more than 3 times that of bulk ceramics. Moreover, the Gyroid structure also has excellent compressive strength. Therefore, this work highlights the great potential of 3D printing technology in developing microarchitecture piezoceramics with ultrahigh electromechanical response.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring spatial beam shaping in laser powder bed fusion: High-fidelity simulation and in-situ monitoring","authors":"","doi":"10.1016/j.addma.2024.104420","DOIUrl":"10.1016/j.addma.2024.104420","url":null,"abstract":"<div><div>Laser beam shaping is a novel and relatively unexplored method for controlling the melt pool conditions during metal additive manufacturing (MAM) processes, but even so it still holds good promise for achieving site-specific tailored properties. In this work, a comprehensive numerical and experimental campaign is carried out to explore this subject within metal laser powder bed fusion (LPBF). More specifically, a multiphysics numerical model is implemented for simulating the heat and fluid flow conditions during LPBF of Ti6Al4V using arbitrary circular beam shapes with various power distributions spanning from a pure Gaussian beam to a pure ring beam profile. The model is subsequently coupled with cellular automata to describe the beam shape effects on the microstructure evolution. Model validation is carried out in a two-fold manner. First, we compare the predicted melt pool cross-section with the one from ex-situ single track experiments, and we find a deviation of less than 9 % in melt pool dimensions. Secondly, advanced <em>in-situ</em> X-ray monitoring is carried out to unravel the melt pool dynamics and we find that the predicted morphology closely matches the <em>in-situ</em> X-ray results. Moreover, it is shown that at lower laser power, a bulge of liquid metal forms at the center of the melt pool when employing ring profiles, and this is ascribed to the absence of recoil pressure at the center of the ring beam. Furthermore, increasing the laser power seems to destabilize the melt pool regime, as the central bulge transforms into a liquid metal jet that periodically collapses and breaks up into hot spatter. Based on the results, we believe that our multiphysics modelling methodology, opens up new pathways for predicting how laser beam shaping influences porosity, surface roughness as well as microstructure formation in LPBF processes.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214860424004664/pdfft?md5=217af1ed146303b409679212221cc4ca&pid=1-s2.0-S2214860424004664-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel solid-state metal additive manufacturing process – Laser-induced Supersonic Impact Printing (LISIP): Exploration of process capability","authors":"","doi":"10.1016/j.addma.2024.104356","DOIUrl":"10.1016/j.addma.2024.104356","url":null,"abstract":"<div><p>Solid-state metal additive manufacturing (AM) techniques offer unique capabilities for direct printing of metallic materials towards a variety of applications. In this work, we developed a novel solid-state metal AM process, named laser-induced supersonic impact printing (LISIP), in which the laser shock-induced impact loading was utilized to trigger the adiabatic shearing phenomenon at metal-metal interfaces towards solid-state three-dimensional (3D) printing of metallic materials. The design of LISIP was inspired by cold spray, explosive welding, and laser impact welding. An experimental investigation was conducted to explore the process capability of LISIP, with a focus on 3D micro-lamination of metallic structure, AM of dissimilar materials, and printing-on-demand direct writing at various length scales from micrometer to centimeter. Steel, copper, aluminum, titanium, and magnesium alloys were used as foil and/or substate for experimentation. Moreover, the microstructure at bonding interfaces were characterized to understand the microstructure evolution as induced by adiabatic shearing. The bonding quality was evaluated using the lap shear test. The mechanisms involved in LISIP including the laser-matter interaction and adiabatic shearing bonding were investigated using first-principles modeling and finite element method simulation. In addition, the technical challenges, scientific knowledge gaps, future research directions, and potential applications of LISIP were deliberated. We envision that the findings and knowledge gained in this work will serve as the first milestone towards the establishment of LISIP for broader impacts.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mesoscale multilayer multitrack modeling of melt pool physics in laser powder bed fusion of lattice metal features","authors":"","doi":"10.1016/j.addma.2024.104365","DOIUrl":"10.1016/j.addma.2024.104365","url":null,"abstract":"<div><p>This paper reports on the development of a mesoscale multiphysics numerical model for predicting the dimensions of melt pool zones in Laser Powder Bed Fusion process, in a multilayer and multitrack application dedicated to the manufacturing of lattice metal features. In such context, a clear need emerges to study laser-matter interaction regarding the persisting questions surrounding the comprehension of melt pool. An experimental campaign involving thin pillars made of the nickel-based superalloy IN718 is presented, highlighting the complexity introduced by the thin tracks superposition. Then, a continuous mesoscale numerical model, considering heat transfer, melt pool flow, and vaporization phenomena, and its extension to multilayer-multitrack simulation is detailed. Some discussions about the numerical approach and its ability to predict the global morphology and dimensions of melt pool zones and resulting tracks after solidification are proposed. Finally, comparisons between the experiments and the numerical model show good agreement, with a maximum relative error of 8 % observed for remelted zone depth. This study demonstrates the capability of the present approach to help in understanding the influence of process parameters on melt pool shape and, thereafter, to determine process parameters to optimize for lattice features building.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding coaxial photodiode-based multispectral pyrometer measurements at the overhang regions in laser powder bed fusion for part qualification","authors":"","doi":"10.1016/j.addma.2024.104398","DOIUrl":"10.1016/j.addma.2024.104398","url":null,"abstract":"<div><p>Coaxial photodiode monitoring sensors provide a digital signature at the melt pool level in laser powder bed fusion (L-PBF), facilitating faster part qualification. However, current signatures are plagued by significant noise and signal variation and show counterintuitive trends such as a decrease in measured temperature near overhang surfaces. This paper investigates the behavior of coaxial photodiode-based melt pool monitoring (PD-MPM) thermal measurements at overhang regions by conducting a combination of experiments and multiphysics simulations. High-speed <em>in situ</em> synchrotron X-ray imaging is coupled with a coaxial photodiode system to enable comparison of the observed melt pool phenomena and monitoring signals during double-track AlSi10Mg experiments. A multiphysics model is developed to simulate the melt pool dynamics and concurrent sensor signals throughout the process. We propose a surrogate model that clarifies the correlation between sensor signals and melt pool temperature. Both experimental and simulation results emphasize the significant impacts of laser energy and keyhole formation on solid-liquid interface discontinuities and PD-MPM signals. Results reveal that a boiling region with a relatively smaller projected area, as near an overhang, can lead to a decrease in the measured melt pool temperature, even when the true peak temperature remains constant, meaning that PD-MPM temperature measurements cannot be used to estimate absolute melt pool temperature. Consequently, in overhang regions, interaction between the melt pool and underlying powder results in an abruptly deforming melt pool and a pronounced decrease in both individual photodiode intensities and overall measured melt pool temperature. This work illustrates how to correctly interpret the coaxial photodiode monitoring signals in L-PBF by uncovering the intricate dynamics within the melt pool, particularly in challenging overhang regions, and pave the foundation for data-driven part qualification.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142157973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the impact of short fibre reinforcement and extrusion properties on microstructure of 3D printed polycarbonate composites","authors":"","doi":"10.1016/j.addma.2024.104423","DOIUrl":"10.1016/j.addma.2024.104423","url":null,"abstract":"<div><p>In the evolving realm of additive manufacturing, this study investigates the microstructural and mechanical implications of short fibre reinforcement within Polycarbonate (PC) composites fabricated via material extrusion (MEX). The research specifically examines the roles of extrusion temperature, extrusion multiplier and fibre content on void content and fibre alignment, with a focus on their influence on inter-bead strength and overall print quality. Through a combination of high-resolution micro-CT scanning and mechanical testing, the study reveals that an increase in the extrusion multiplier significantly enhances fibre-bridging up to 47 % and inter-bead adhesion up to 237 % depending on the fibre content. It also traces an optimal fibre content threshold that maximizes benefits of fibre bridging, thereby bolstering the mechanical properties of the material. The comprehensive analysis demonstrates that precise control over the extrusion parameters as well as filament quality are crucial for exploiting the full potential of fibre reinforcement in 3D printed structures. This research advances our understanding of MEX in fabricating short fibre-reinforced composites, offering novel insights for tailoring material properties to meet the demands of high-performance applications.</p></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":null,"pages":null},"PeriodicalIF":10.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S221486042400469X/pdfft?md5=95feb9d54b1235b5a02dbb35337990f7&pid=1-s2.0-S221486042400469X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}