Search

In the process of high temperature service, the mechanical properties of cutting tools decrease sharply due to the peeling of the protective coating. However, the mechanism of such coating failure remains obscure due to the complicated interaction between atomic structure, temperature, and stress. This dynamic evolution nature demands both large system sizes and accurate description on the atomic scale, raising challenges for existing atomic scale calculation methods. Here, we developed a deep neural network (DNN) potential for Ti–N binary systems based on first-principles study datasets to achieve quantum-accurate large-scale atomic simulation. Compared with empirical interatomic potential based on the embedded-atom-method, the developed DNN-potential can accurately predict lattice constants, phonon properties, and mechanical properties under various thermodynamic conditions. Moreover, for the first time, we present the atomic evolution of the fracture behavior of large-scale rocksalt-structure (B1) TiN systems coupled with temperature and stress conditions. Our study validates that interatomic brittle fractures occur when TiN stretches beyond its tensile yield point. Such simulation of coating fracture and cutting behavior based on large-scale atoms can shed new light on understanding the microstructure and mechanical properties of coating tools under extreme operating conditions. [ABSTRACT FROM AUTHOR]

The magnetite oxidation process involves magnetite surface adsorption and O2 dissociation, and the presence of impurity elements such as silicon inevitably affects the magnetite surface adsorption process. To explore and analyze the surface adsorption and oxidation behaviors of silicon‐doped Fe3O4, thermogravimetric experiments and density functional theory methods are used to investigate the physicochemical properties of this material during magnetite oxidation. The results of experiments show that with the increase of SiO2 content, the peaks of the oxidation reaction gradually migrate to the high‐temperature region, the initial oxidation temperature of the mineral increases, and the average oxidation rate decreases. The results of calculations show that when the surface system is doped with Si atoms, the relaxation time of the adsorption and dissociation of oxygen on the surface is prolonged, and the presence of Si isomerization tends to stabilize the crystal lattice structure, reduce the migration of ions, and decrease the mineral's oxidizing properties. [ABSTRACT FROM AUTHOR]

This article discusses a novel artificial intelligence (AI)-enabled approach to the rapid screening and diagnosis of acute promyelocytic leukemia (APL) using bone marrow morphology. A convolutional neural network (CNN) with embedded attention mechanisms was developed to recognize APL in microscope images. The model was trained and evaluated using a large dataset of bone marrow smear images, achieving high accuracy and performance. The AI-assisted system, called CELLSEE, showed potential for improving the speed and accuracy of APL diagnosis, enabling early identification and treatment. The study highlights the importance of AI in medical diagnostics and its potential for reducing mortality rates in APL cases. [Extracted from the article]

Metallic uranium-based alloys, with d-transition metals such as Nb, Mo, and Zr, are promising candidates for actinide fuel. For this purpose, their behaviors under changing physical stimuli need to be understood. Here, we systematically investigate U–Nb intermetallic compounds and predict new compound formations under different pressures using the first-principles swarm-intelligence structure searching method. Two new compounds (U1Nb6 and U2Nb1) were identified to be thermodynamically stable at ambient and high pressures. U1Nb6 has a triclinic symmetry that is stable in the pressure range of 0–200 GPa, while U2Nb1 has a hexagonal closely packed structure at low pressure and transforms to a simple hexagonal lattice at 20 GPa. Other compounds, particularly U-rich ones (U3Nb1, U4Nb1, U5Nb1, and U6Nb1), are found metastable at ambient and high pressures, and all have orthorhombic structures. The structural, vibrational, electronic, and mechanical properties of predicted U-rich compounds were thoroughly studied using density-functional theory. The results of phonon spectra and elastic constant show that the predicted new structures are dynamically and mechanically stable in the corresponding pressure range. Also, these newly identified U-rich compounds exhibit strong composition dependence, and the pressure-induced enhancements of structural stability and mechanical performances are evident. These findings shall enrich the understanding of U-based alloys and serve as meaningful predictions for experimental research in the future. [ABSTRACT FROM AUTHOR]

In order to solve the problems of poor hole-filling performance and the high seed-breakage rate of conventional rice bud seed precision hole direct seed-metering devices, a side-filled rice precision hole direct seed-metering device was developed, and the mechanism and force analyses for seeding operations were carried out. The key factors affecting seeding quality were determined: rotation speed, seeding angle and seeding height. By coupling the discrete element method (DEM) and multi-rigid body dynamics (MBD), the seed breakage rate and seeding performance at different rotation speeds were analyzed. Single-factor bench testing was used to analyze the effect of a duckbill unit on seeding performance under different factor levels. The three-factor and five-level quadratic regression orthogonal rotation center combination test methods were used to obtain the optimal working parameter combination. The test results showed that when the rotation speed was 47 r/min, the seeding angle was 19°, and the seeding height was 180 mm, the qualified index of seeding was 92.03%, the hole diameter qualified index was 91.62%, and the hole distance variation index was 7.17%. This study provides a reference for the research of mechanical rice sprouting seed-metering devices. [ABSTRACT FROM AUTHOR]

Preharvest threshing is a harvesting method that focuses on collecting rice grains while leaving the rice straw unharvested. Investigating the interaction mechanism between the machine and rice during the operation process and its correlation with harvest losses is crucial for enhancing harvest quality. In this study, structural design and operational mechanism analysis of the combs was conducted through theoretical analysis. By extracting the relevant parameters of rice plants, a model of entire-plant rice during the harvesting period was established based on the discrete element method (DEM). Numerical simulation studies were conducted to clarify the interaction mechanism between the machinery and rice at different operating stages and under various operating parameters, as well as the impact of this interaction on operational quality. The simulation results revealed that various operating parameters had a significant impact on the sliding-cut effect between the combs and rice. A higher cylinder rotation speed enhanced the effect, whereas increased forward velocity hampered it. Additionally, the effect initially improved and then decreased with a higher threshing height. In the bench test, high-speed cameras were used to verify and further analyze the comb–rice interaction mechanism and explore the optimal working parameter combination. The results showed that at a rotation speed of 616 r/min, a forward velocity of 0.91 m/s, and a threshing height of 792 mm, the grain loss rate was 1.997%, and the impurity rate was 4.073%. The harvesting losses were effectively reduced, validating the effectiveness of the study on the interaction between the machinery and rice. [ABSTRACT FROM AUTHOR]

Highlights: Strain induces coupling in Bi12O17Br2 and Cu porphyrin-based monoatomic layer (PML-Cu), constructing Bi–O bonding interface in PML-Cu/BOB (PBOB). Surface interface dual polarization boosts internal electric field, promoting electron transfer. PML-Cu provides high density of dispersed active Cu sites in PBOB, enhancing CO2 photoreduction. The insufficient active sites and slow interfacial charge transfer of photocatalysts restrict the efficiency of CO2 photoreduction. The synchronized modulation of the above key issues is demanding and challenging. Herein, strain-induced strategy is developed to construct the Bi–O-bonded interface in Cu porphyrin-based monoatomic layer (PML-Cu) and Bi12O17Br2 (BOB), which triggers the surface interface dual polarization of PML-Cu/BOB (PBOB). In this multi-step polarization, the built-in electric field formed between the interfaces induces the electron transfer from conduction band (CB) of BOB to CB of PML-Cu and suppresses its reverse migration. Moreover, the surface polarization of PML-Cu further promotes the electron converge in Cu atoms. The introduction of PML-Cu endows a high density of dispersed Cu active sites on the surface of PBOB, significantly promoting the adsorption and activation of CO2 and CO desorption. The conversion rate of CO2 photoreduction to CO for PBOB can reach 584.3 μmol g−1, which is 7.83 times higher than BOB and 20.01 times than PML-Cu. This work offers valuable insights into multi-step polarization regulation and active site design for catalysts. [ABSTRACT FROM AUTHOR]

Mycosporine-like amino acids (MAAs) are a class of water-soluble active substances produced by various aquatic organisms. However, due to the limitations of low accumulation of MAAs in organisms, the cumbersome extraction process, difficult identification, and high cost, MAAs have not yet been widely used in human life. Recently, there has been an emergence of heterologous synthesis for MAAs, making increasing yield the key to the quantification and application of MAAs. This review summarizes the latest research progress of MAAs, including: (1) introducing the biodistribution of MAAs and the content differences among different species to provide a reference for the selection of research subjects; (2) elaborating the species and molecular information of MAAs; (3) dissecting the synthesis mechanism and sorting out the synthesis pathways of various MAAs; (4) summarizing the methods of extraction and identification, summarizing the advantages and disadvantages, and providing a reference for the optimization of extraction protocols; (5) examining the heterologous synthesis method; and (6) summarizing the physiological functions of MAAs. This paper comprehensively updates the latest research status of MAAs and the various problems that need to be addressed, especially emphasizing the potential advantages of heterologous synthesis in the future production of MAAs. [ABSTRACT FROM AUTHOR]