Lattice structures, which are also known as architected cellular structures, have been applied in various industrial sectors, owing to their fascinated performances, such as low elastic modulus, high ...stiffness-to-weight ratio, low thermal expansion coefficient, and large specific surface area. The lattice structures fabricated by conventional manufacturing technologies always involve complicated process control, additional assembly steps, or other uncontrollable factors. Furthermore, limited types of unit cells can be used to construct lattice structures when using conventional processes. Fortunately, additive manufacturing technology, based on a layer-by-layer process from computer-aided design models, demonstrates the unique capability and flexibility and provides an ideal platform in manufacturing complex components like lattice structures, resulting in an effective reduction in the processing time to actual application and minimum of material waste. Therefore, additive manufacturing relieves the constraint of structure design and provides accurate fabrication for lattice structures with good quality. This work systematically presents an overview of conventional manufacturing methods and novel additive manufacturing technologies for metallic lattice structures. Afterward, the design, optimization, a variety of properties, and applications of metallic lattice structures produced by additive manufacturing are elaborated. By summarizing state-of-the-art progress of the additively manufactured metallic lattice structures, limitations and future perspectives are also discussed.
Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. ...However, state‐of‐the‐art high‐performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their complicated processing methods are a major impediment to commercialization. Here, inspired by the high‐entropy alloy concept with its inherent multinary nature and using a glassy alloy design with its chemical homogeneity and tunability, we present a scalable strategy to alloy five equiatomic elements, PdPtCuNiP, into a high‐entropy metallic glass (HEMG) for HER in both alkaline and acidic conditions. Surface dealloying of the HEMG creates a nanosponge‐like architecture with nanopores and embedded nanocrystals that provides abundant active sites to achieve outstanding HER activity. The obtained overpotentials at a current density of 10 mA cm−2 are 32 and 62 mV in 1.0 m KOH and 0.5 m H2SO4 solutions, respectively, outperforming most currently available electrocatalysts. Density functional theory reveals that a lattice distortion and the chemical complexity of the nanocrystals lead to a strong synergistic effect on the electronic structure that further stabilizes hydrogen proton adsorption/desorption. This HEMG strategy establishes a new paradigm for designing compositionally complex alloys for electrochemical reactions.
A high‐entropy metallic glass with multinary nature and chemical homogeneity is developed by a scalable metallurgical technique. Dealloying creates a nanosponge‐like architecture with embedded nanocrystals that provides abundant active sites to achieve outstanding hydrogen evolution activity in both alkaline and acidic conditions. This work will provide a roadmap for designing alloy catalysts for many years to come.
Metallic glasses (MGs) with the metastable nature and random atomic packing structure have attracted large attention in the catalytic family due to their superior catalytic performance. In contrast, ...their crystalline counterparts are restricted by the highly ordered packing structure, fewer surface active sites, and crystallographic defects for catalytic activity. The uncertainty of the different catalytic mechanisms and the intrinsic characteristics correlated to MGs and their crystalline counterparts become a major impediment to promote their catalytic efficiencies and widespread applications. Herein, it is reported that the excellent catalytic behavior in Fe‐based MGs goes through a detrimental effect with the partial crystallization, but receives a compelling rejuvenation in the full crystallization. Further investigation reveals that multiphase intermetallics with electric potential differences in fully crystallized alloys facilitate the formation of galvanic cells. More importantly, extensively reduced grain boundaries due to grain growth greatly weaken electron trapping and promote inner electron transportation. The relatively homogenous grain‐boundary corrosion in the intermetallics contributes to well‐separated phases after reaction, leading to refreshment of the surface active sites, thereby quickly activating hydrogen peroxide and rapidly degrading organic pollutants. The exploration of catalytic mechanisms in the crystalline counterparts of MGs provides significant insights into revolutionize novel catalysts.
Fully crystallized alloys gained by annealing of metallic glasses show excellent rejuvenated catalytic capabilities for ultrafast activation of peroxide. As galvanic cells form in the fully crystallized alloys, a grain growth contributing to extensively reduced grain boundaries greatly weakens electron trapping and promotes inner electron transportation, providing a significant insight into exploit novel catalysts.
Metallic glass (MG), with the superiorities of unique disordered atomic structure and intrinsic chemical heterogeneity, is a new promising and competitive member in the family of environmental ...catalysts. However, what is at stake for MG catalysts is that their high catalytic efficiency is always accompanied by low stability and the disordered atomic configurations, as well as the structural evolution, related to catalytic performance, which raises a primary obstacle for their widespread applications. Herein, a non‐noble and multicomponent Fe83Si2B11P3C1 MG catalyst that presents a fascinating catalytic efficiency while maintaining remarkable stability for wastewater remediation is developed. Results indicate that the excellent efficiency of the MG catalysts is ascribed to a unique atomic coordination that causes an electronic delocalization with an enhanced electron transfer. More importantly, the in situ self‐reconstructed hierarchical gradient structure, which comprises a top porous sponge layer and a thin amorphous oxide interfacial layer encapsulating the MG surface, provides matrix protection together with high permeability and more active sites. This work uncovers a new strategy for designing high‐performance non‐noble metallic catalysts with respect to structural evolution and alteration of electronic properties, establishing a solid foundation in widespread catalytic applications.
Fe‐based metallic glass catalysts with a disordered atomic structure are prepared by a melt‐spinning technique. The metallic glass catalysts present excellent catalytic performance in both efficiency and stability when compared to the state of the art. The high catalytic efficiency is due to their intrinsic formation of metallic bonds and electronic delocalization, while the superior catalytic stability is owing to their self‐reconstruction ability.
Metallic glasses (MGs), with their unique disordered atomic packing structure and superior catalytic capabilities, have gradually been realized with their significance in the field of catalysis. As a ...new type of promising catalyst, recent reports have demonstrated that MGs exhibit many excellent catalytic properties in wastewater treatment, such as ultrafast catalytic efficiency and reliable stability with a reduced metal leaching effect, etc. This review introduces, for the first time, recent developments in using MGs with various atomic components and excellent catalytic performance as environmental catalysts. In terms of the unique properties of MGs, this article provides a full discussion of several effects of their physical characteristics on catalytic reactivity, such as structural relaxation, crystallization, and rejuvenation, electronic structure, atomic configuration, thermophysical property, atomic composition, surface roughness, residual stress, and porosity by dealloying. The catalytic performance, including decolorization, mineralization, metal leaching, sustainability and reusability, as well as the effects of different chemical parameters, is systematically reviewed. This review also delivers several important prospects in further developing MG catalysts, offering new research opportunities into the study of their novel functional applications and providing new insights into the synthesis of novel catalysts.
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•Corrosion behavior of laser powder bed fusion produced Ti–6Al–4V samples was investigated.•Static and dynamic Hank’s solutions were selected as the corrosion environments.•Flow ...solution degrades passive film of sample and thereby the corrosion resistance.•Flow solution promotes the deposition of calcium phosphate and hydroxyapatite.
The corrosion behavior of laser powder bed fusion produced (L-PBF-produced) titanium alloys involving flowing body fluid is still unclear. Therefore, this work investigates in vitro corrosion behavior and the characteristics of passive films formed on L-PBF-produced Ti–6Al–4V in both static and dynamic Hank’s solutions. Electrochemical measurements, immersion tests, X-ray photoelectron spectroscopy and scanning electron microscopy were conducted. In comparison to the L-PBF-produced Ti–6Al–4V in static Hank’s solution, the samples showed lower charge transfer resistance and higher passivation current density (anodic current density as well) in dynamic Hank’s solution. Meanwhile, a more apparent deposition of apatite and hydroxyapatite is found on the L-PBF-produced Ti–6Al–4V in dynamic Hank’s solution. Such outcomes mainly result from the enhancement of film/solution interfacial transportation in dynamic Hank’s solution. The dynamic Hank’s solution provides more calcium and phosphate ions to the surface of the passive film and also takes away the dissolved metal ions. Therefore, more salt deposition and a lower-quality passive film are found.
Amorphous metal nanoparticles (A-NPs) have aroused great interest in their structural disordering nature and combined downsizing strategies (
e.g.
nanoscaling), both of which are beneficial for ...highly strengthened properties compared to their crystalline counterparts. Conventional synthesis strategies easily induce product contamination and/or size limitations, which largely narrow their applications. In recent years, laser ablation in liquid (LAL) and laser fragmentation in liquid (LFL) as "green" and scalable colloid synthesis methodologies have attracted extensive enthusiasm in the production of ultrapure crystalline NPs, while they also show promising potential for the production of A-NPs. Yet, the amorphization in such methods still lacks sufficient rules to follow regarding the formation mechanism and criteria. To that end, this article reviews amorphous metal oxide and carbide NPs from LAL and LFL in terms of NP types, liquid selection, target elements, laser parameters, and possible formation mechanism, all of which play a significant role in the competitive relationship between amorphization and crystallization. Furthermore, we provide the prospect of laser-generated metallic glass nanoparticles (MG-NPs) from MG targets. The current and potential applications of A-NPs are also discussed, categorized by the attractive application fields
e.g.
in catalysis and magnetism. The present work aims to give possible selection rules and perspective on the design of colloidal A-NPs as well as the synthesis criteria of MG-NPs from laser-based strategies.
Pulsed laser strategies (
i.e.
pulsed laser ablation and fragmentation in liquid) have been reviewed with a focus on the synthesis and processing of amorphous metal nanoparticles. The possible formation criteria and mechanism have been discussed.
Background
In pancreatic cancer, methods to predict early recurrence (ER) and identify patients at increased risk of relapse are urgently required.
Purpose
To develop a radiomic nomogram based on MR ...radiomics to stratify patients preoperatively and potentially improve clinical practice.
Study Type
Retrospective.
Population
We enrolled 303 patients from two medical centers. Patients with a disease‐free survival ≤12 months were assigned as the ER group (n = 130). Patients from the first medical center were divided into a training cohort (n = 123) and an internal validation cohort (n = 54). Patients from the second medical center were used as the external independent validation cohort (n = 126).
Field Strength/Sequence
3.0T axial T1‐weighted (T1‐w), T2‐weighted (T2‐w), contrast‐enhanced T1‐weighted (CET1‐w).
Assessment
ER was confirmed via imaging studies as MRI or CT. Risk factors, including clinical stage, CA19‐9, and radiomic‐related features of ER were assessed. In addition, to determine the intra‐ and interobserver reproducibility of radiomic features extraction, the intra‐ and interclass correlation coefficients (ICC) were calculated.
Statistical Tests
The area under the receiver‐operator characteristic (ROC) curve (AUC) was used to evaluate the predictive accuracy of the radiomic signature in both the training and test groups. The results of decision curve analysis (DCA) indicated that the radiomic nomogram achieved the most net benefit.
Results
The AUC values of ER evaluation for the radiomics signature were 0.80 (training cohort), 0.81 (internal validation cohort), and 0.78 (external validation cohort). Multivariate logistic analysis identified the radiomic signature, CA19‐9 level, and clinical stage as independent parameters of ER. A radiomic nomogram was then developed incorporating the CA19‐9 level and clinical stage. The AUC values for ER risk evaluation using the radiomic nomogram were 0.87 (training cohort), 0.88 (internal validation cohort), and 0.85 (external validation cohort).
Data Conclusion
The radiomic nomogram can effectively evaluate ER risks in patients with resectable pancreatic cancer preoperatively, which could potentially improve treatment strategies and facilitate personalized therapy in pancreatic cancer.
Level of Evidence: 4
Technical Efficacy: Stage 4
J. Magn. Reson. Imaging 2020;52:231–245.
Heat and mass transports through a rough surface are among the most fundamental and important phenomena in either natural or engineering problems. In this paper, theoretical modelling and direct ...simulation Monte Carlo method are employed to study the heterogeneous reaction–diffusion features induced by microscale roughness which is comparable to the molecular mean free path of the ambient gas. A quasi-one-dimensional homogeneous model is proposed, and it consists of an external diffusion region outside the roughness elements and an internal reaction–diffusion region which could be equivalent to a smooth surface with an effective chemical property. The external macroscopic diffusion can be characterized by a non-equilibrium criterion – the Damköhler number. The internal diffusion in micro-cavities must be analysed by considering the rarefied gas effects on the diffusivity, and another non-equilibrium criterion, the Thiele number, is introduced to evaluate the effective boundary condition imposed on the external region. Analytical formulae based on these criteria are derived to predict the equivalent surface reaction–diffusion performance, and the predictions compare well with the numerical results of different types of surface reaction, even on the three-dimensional roughness. This reveals that the roughness could either enhance or weaken the apparent reaction rate depending on the non-equilibrium degree. This study could enrich our understanding of the gas–surface interactions on a rough wall, such as the oxidation, catalysis and energy accommodation, and also preliminarily provides a practical method for evaluation of the aerothermochemical performance of coating materials of hypersonic vehicles.
Designing the kinetic pathways of assembling macromolecules such as block copolymers and DNA strands is crucial not only for an achievement of thermodynamically equilibrium nanostructures over ...macroscopic areas, but also for a better understanding of formation process of higher-level superstructures where well-tailored assemblies act as mesoscopic building units. Theoretical analysis and computer simulations provide excellent opportunities to microscopically reveal the kinetics and mechanism of structural evolution as well as the collective behaviors of building units. In this perspective, we summarize our efforts of theoretical and computational modelling to understand the long-range ordering mechanisms and the organization kinetics of assembling macromolecules along designable pathways. First, we present the computational modelling and recent strategies of designable pathways for the achievement of long-range ordering. Then, from the computational views, we give the applications of pathway-designed strategies to explore the ordering mechanism and kinetics in the course of structural evolution, covering the block copolymers and their nanocomposites under zone annealing as well as the hierarchical self-assembly of mesoscopic building units (e.g., patchy micelles and DNA-functionalized nanoparticles). Finally, we outlook future directions in the field of designable pathways for the achievement of long-range ordered nanostructures. This perspective could promote further efforts towards the wide applications of theoretical and computational modelling in the construction of soft hybrid metamaterials.
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