Two‐dimensional (2D) metal‐organic framework (MOF) nanosheets, as an emerging type of 2D materials, attract numerous attention due to their unique properties. First, the ultrathin thickness and ...nanoscale of the materials results in homogeneous dispersion in aqueous solution, giving the materials more opportunities to be utilized in solution chemistry, especially beneficial to the biomimetic catalysis and bio‐related analytical applications. Second, the large surface area and accessible active sites of the MOF nanosheets are favorable to the binding between materials and the substrate, leading to their superior performance in catalysis, sensing and enzyme inhibition. Third, the suitable sizes of nanopores on the 2D MOF nanosheets give them the abilities to act as membranes for highly selective and energy‐saving gas separation. This minireview covers the synthesis, characterization as well as bio‐related and separation applications of 2D MOF nanosheets.
Nanosheets: Two‐dimensional (2D) metal‐organic frameworks (MOFs) nanosheets, as an emerging type of 2D materials, are attracting increasing applications in catalysis, sensing, enzyme inhibition, MALDI‐TOF matrix and gas separation. This Minireview summarizes 2D MOF nanosheets and their diverse applications with the integration of the fundamental structures and their application mechanism.
Deep Transfer Bug Localization Huo, Xuan; Thung, Ferdian; Li, Ming ...
IEEE transactions on software engineering,
07/2021, Letnik:
47, Številka:
7
Journal Article
Recenzirano
Many projects often receive more bug reports than what they can handle. To help debug and close bug reports, a number of bug localization techniques have been proposed. These techniques analyze a bug ...report and return a ranked list of potentially buggy source code files. Recent development on bug localization has resulted in the construction of effective supervised approaches that use historical data of manually localized bugs to boost performance. Unfortunately, as highlighted by Zimmermann et al., sufficient bug data is often unavailable for many projects and companies. This raises the need for cross-project bug localization - the use of data from a project to help locate bugs in another project. To fill this need, we propose a deep transfer learning approach for cross-project bug localization. Our proposed approach named TRANP-CNN extracts transferable semantic features from source project and fully exploits labeled data from target project for effective cross-project bug localization. We have evaluated TRANP-CNN on curated high-quality bug datasets and our experimental results show that TRANP-CNN can locate buggy files correctly at top 1, top 5, and top 10 positions for 29.9, 51.7, 61.3 percent of the bugs respectively, which significantly outperform state-of-the-art bug localization solution based on deep learning and several other advanced alternative solutions considering various standard evaluation metrics.
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•Trace nanoparticles stimulated nuclei of α-Al and weakened the micro-segregation.•Nano-TiC-TiB2 was more effective stimulating nucleation of α-Al.•Nano-TiC-TiB2 was more effective in ...promoting and hindering recrystallization.•The nucleation rate of Al2Cu was increased by trace nanoparticles during aging.
In this paper, we took cold-rolled Al-Cu5.0-Mg0.5-Si0.5 alloy as the research object. The roles of 0.1 wt% in-situ nano-TiC and nano-TiC-TiB2 in solid–liquid and solid-state transformations (solution plus aging precipitation) were systematically investigated and compared. We found that trace in-situ nanoparticles can stimulate the nucleation of α-Al dendrites and hinder their growth, meanwhile serving as the heat storage and heat sustained-release carriers during solid–liquid transformation. In the process of solid-state transformation, recrystallization nucleation is promoted, and grain boundaries are pinned by nanoparticles. Meanwhile, the nucleation of Al2Cu is accelerated, and refined Al2Cu distributes more uniformly. Besides, similarities and differences in the manipulation mechanisms of nano-TiC and nano-TiC-TiB2 during solid–liquid and solid-state transformations were analyzed. The mechanical properties and the responsible strengthening mechanisms were discussed in detail.
China has the largest afforested area in the world (∼62 million hectares in 2008), and these forests are carbon sinks. The climatic effect of these new forests depends on how radiant and turbulent ...energy fluxes over these plantations modify surface temperature. For instance, a lower albedo may cause warming, which negates the climatic benefits of carbon sequestration. Here, we used satellite measurements of land surface temperature (LST) from planted forests and adjacent grasslands or croplands in China to understand how afforestation affects LST. Afforestation is found to decrease daytime LST by about 1.1 ± 0.5 °C (mean ± 1 SD) and to increase nighttime LST by about 0.2 ± 0.5 °C, on average. The observed daytime cooling is a result of increased evapotranspiration. The nighttime warming is found to increase with latitude and decrease with average rainfall. Afforestation in dry regions therefore leads to net warming, as daytime cooling is offset by nighttime warming. Thus, it is necessary to carefully consider where to plant trees to realize potential climatic benefits in future afforestation projects.
As interfaces play a more important role in high-volume-fraction ceramic/metal composites because of containing more hetero-phase interfaces, it is a great challenge to control the interfaces in such ...composites to balance their strength and plasticity and to obtain high performances. In this work, 50–60 vol% (TiC + TiB2)/Al composites were fabricated in Al–Ti–B4C system via a one-step method of reaction and densification, and their interface bonding and mechanical properties were compared with those of in-situ TiC/Al composites. Apparently, the defects, such as interfacial discontinuity, macro-pores, coarsening and agglomeration of particles, caused by increased ceramic content in the TiC/Al composites, are eliminated in the (TiC + TiB2)/Al composites using Al–Ti–B4C system. The 60 vol% (TiC + TiB2)/Al composite exhibits significantly enhanced mechanical properties, i.e. 70.5%, 60.7% and 69.8% respectively higher yield strength, ultimate compressive strength and plastic strain than 60 vol% TiC/Al composite. Such enhanced mechanical properties are attributed to the improvement in interface bonding strength and therefore the increase in the energy dissipation of crack propagation. The formation of enhanced interface in the (TiC + TiB2)/Al composites results from the reduction in the reaction heat in the Al–Ti–B4C system, improved crystallographic match and improved adhesion work between ceramic particles and matrix. This work may provide a new idea for the design and control of interfaces in high-volume-fraction ceramic-metal composites.
•High-volume-fraction (TiC + TiB2)/Al composites with enhanced property were fabricated.•Interface between ceramic and matrix is designed by lattice match and adhesion work.•Al–Ti–B4C reaction system is used to control the interface formation in the composite.•(TiC + TiB2)/Al composite has significantly improved performance than TiC/Al composite.•A new idea is provided for design and control interfaces in ceramic/metal composite.
There is an increasingly urgent need of lightweight components in aerospace industry, among which aluminum (Al) alloys have been the optimal materials of choice for aircraft structural parts since ...being used in the Junkers F.13 aircraft in the 1920s. Compared to other metal materials, Al alloys have a lower density, and the use of Al alloys reduces the total weight of the aircraft and improves fuel efficiency and load capacity. Meanwhile, the strength and hardness of Al alloys with alloying and heat treatment can be significantly enhanced for uses in high loads and vibration environments. Furthermore, in the harsh aerospace environment, aircraft may receive various climatic conditions and chemical corrosion. Due to good corrosion and fatigue resistance, Al alloys demonstrate excellent performance under these conditions, ensuring the long–term service life of aircraft. In addition, Al alloys have good recyclability, and they can be recycled to reduce resource consumption and environmental load, in line with the principle of sustainable development. In recent years, although composites have been widely used in aerospace, high–strength Al alloys are still in an indispensable position. Therefore, this article reviews the progress and applications of Al alloys commonly used in aerospace. The common strengthening methods and advanced manufacturing and processing technologies of Al alloy are also discussed, which can provide references for the development of advanced high–performance aviation Al alloys in the future.
Titanium carbide (TiC) nanoparticles with well‐designed exposed crystal planes perform intriguing prospects for functional and engineering applications. In this study, a simple and controllable in ...situ synthesis strategy was proposed for the synthesis of TiC nanoparticles with specific morphology. Reaction behaviors suggested that most of TiC nanoparticles were formed by an instantaneous reaction between Al3Ti and Al4C3 in the Al‐rich melt and the resultant morphology was controlled by the discrepant growing rates of (100) and (111) crystal planes. In addition, a growth morphology control model was presented for the prediction and manipulation of the morphology of TiC nanoparticles by the doping of different alloying elements Me (Me = Cu, Mg, Mn, Zn, and Si). According to the morphological observations and density functional theory analyses including the interface energy, charge density differences, and orbital hybridization: Cu, Mg, and Zn atoms could stabilize the Al/TiC(111) interface, whereas Mn and Si atoms promoted the rapid growing and disappearance of the TiC(111) planes in the Al melt. This work provides a feasible way to intelligently design and manipulate TiC nanoparticles with desirable exposed crystal planes, and exhibits a promising prospect for personalized applications.
The rational design of artificial solid‐state nanopores is of great importance in the discovery of intriguing ion transport phenomena. 2D metal–organicframework (2D MOF) nanosheets with single ...crystallinity, aligned nanochannels, ultrathin thickness, and diverse functionalities are highly potential solid‐state nanopores. An electrophoretic method is developed to successfully fabricate MOF nanopores supported by SiNx substrate, which is confirmed by high‐resolution transmission electron microscopy. A giant gap around 4 V together with ionic current rectification is discovered in nonlinear voltage‐activated current‐voltage curves, revealing the synergy of the hydrophobic effect and charge effect in MOF nanopores. The charge effect embodies the different contribution current which results from the enrichment and depletion of ions in MOF nanopores by COMSOL simulation. Moreover, 2D MOF nanosheets with different surface charges, hydrophobicity, and pore sizes demonstrate the universality of nanopore fabrication and further confirm the synergistic mechanism. The nonlinear ion transport in the ultrathin MOF nanosheets will provide an opportunity to explore further applications in solid‐state nanopores.
Nonlinear ion transport through the single crystalline two‐dimensional ultrathin metal–organic framework nanosheets is discovered along with a giant gap of low conductance state as well as the rectification inversion. The synergetic mechanism is revealed by the combination of the regulation of physical and chemical parameters and simulations.
The increase in strength usually accompanies by the sacrifice of ductility in the composites. This work proposed a strategy of design and synthesis of in-situ TiB2 particles to effectively tailor the ...microstructures and to enhance the mechanical performance of Al–Si-based composites. The tuning mechanisms for size and morphology of TiB2 particles were investigated by combustion synthesis in the Al–Ti–B reaction system. The nano/submicron-sized TiB2 particles with desirable morphology were then specially selected to construct high-performance Al–Si-based composites. Thanks to the strong interface bonding with a low crystallographic mismatch, TiB2 particles significantly refined the primary α-Al dendrites, eutectic Si and θ’ precipitates in the composites, which were 79.2%, 51.9% and 37.6% respectively smaller than those of the matrix. Numerical modeling results suggested that submicron-sized TiB2 particles were more likely to be engulfed or serve as heterogeneous sites while nano-sized TiB2 particles would be repulsed to the solid/liquid interface to physically restrict the growth of α-Al dendrites. The strength-ductility trade-off dilemma was broken therefore superior mechanical properties were obtained in the composites. This work provides a novel perspective for manipulating Al–Si-based alloys in terms of avoiding poisoning and achieving microstructural refinement and outstanding strength-ductility synergy.
•Novel TiB2 particles were designed and synthesized to enhance the performance of Al–Si-based composites.•The size and morphology tuning mechanisms of in-situ TiB2 particles are revealed in the Al–Ti–B reaction system.•Nano/submicron-sized TiB2 particles exert strong interface bonding and low crystallographic mismatch with Al–Si matrix.•By optimizing the spatial distribution of TiB2 particles, composites outstanding strength-ductility synergy are achieved.
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