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This research utilizes both single crystal and polycrystalline models to probe the fatigue crack propagation mechanism in pure silver via molecular dynamics (MD) simulations. A comprehensive validation approach at both micro and macro scales, incorporating transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), and compact tension (CT) specimen fatigue testing, is developed to verify the reliability of simulation models and results. Simulation findings indicate that the initial crack orientation significantly influences crack propagation. As the crack advances within the crystal, two primary crack propagation mechanisms are discerned: (1) nano-voids appear at the crack tip, and the crack propagates by continuously aggregating with the nano-voids ahead; (2) the formation of Stair-rod dislocations and V-shape stacking faults due to dislocation reactions and slip band movements impedes crack propagation, accompanied by the dislocation reaction of Shockley partial dislocations ( 1 6 <112>) generating Hirth dislocations ( 1 6 <110>). The dislocation reaction is verified through the dislocation analysis of the crack tip area of the CT specimen after fatigue experiment by using TEM. In addition, the results of this study show that the angle between the direction of crack propagation and the grain boundary affects the fatigue crack propagation, e.g. when the angle is less than 60°, the crack rapidly propagates along the grain boundary. The orientation distribution function (ODF) results of EBSD can verify that the polycrystalline model containing 30 grains is a reliable model for the MD simulation of behavior of the crack tip of CT specimen. Lastly, the Paris law constants for pure silver are determined as m = 3.72 and lg C = − 10.77, providing a reference for the fatigue analysis and life prediction of silver components or silver soldering pots in engineering applications. [ABSTRACT FROM AUTHOR]

To reveal the effects of water vapor on the oxidation mechanism of Al–Zr-based materials, the Al2Zr alloy was oxidized in a wet atmosphere. Water vapor achieves the synchronous oxidation of Al and Zr to form amorphous (Al0.67Zr0.33)O1.66 oxide on the Al2Zr surface. The oxidation kinetics of the Al2Zr alloy is significantly retarded by the presence of water vapor. Compared with the oxygen molecules, water molecules are preferentially adsorbed on the surface, thereby providing fewer oxidizing species for wet oxidation than those for oxygen-involved oxidation. This work provides fundamental insights for surficial protection of structural alloys in humid environments. [ABSTRACT FROM AUTHOR]

Automated Breast Ultrasound is a highly advanced breast tumor detection modality that produces hundreds of 2D slices in each scan. However, this large number of slices poses a significant burden for physicians to review. This paper proposes a novel 2.5D tumor detection model, named "ABUSDet," to assist physicians in automatically reviewing ABUS images and predicting the locations of breast tumors in images. At the core of this approach, a sequence of data blocks partitioned from a pre-processed 3D volume are fed to a 2.5D tumor detection model, which outputs a sequence of 2D tumor candidates. An aggregation module then clusters the 2D tumor candidates to produce the ultimate 3D coordinates of the tumors. To further improve the accuracy of the model, a novel mechanism for training deep learning models, called "Deliberate Training," is proposed. The proposed model is trained and tested on a dataset of 87 patients with 235 ABUS volumes. It achieves sensitivities of 77.94%, 75.49%, and 65.19% at FPs/volume of 3, 2, and 1, respectively. Compared with the 2D and 3D object detection models, the proposed ABUSDet model achieves the highest sensitivity with relatively low false-positive rates. [ABSTRACT FROM AUTHOR]

BaTiO3/TiO2@polypyrrole (PPy) composites with hollow multishelled structure (HoMS) were constructed to enhance the electromagnetic wave absorbing properties of BaTiO3-based absorbing material. BaTiO3/TiO2 HoMSs were prepared by hydrothermal crystallization using TiO2 HoMSs as template. Then, FeCl3 was introduced to initiate the oxidative polymerization of pyrrole monomer, forming BaTiO3/TiO2@PPy HoMSs successfully. The electromagnetic wave absorbing properties of BaTiO3/TiO2 HoMSs and BaTiO3/TiO2@PPy HoMSs with different shell number were investigated using a vector network analyzer. The results indicate that BaTiO3/TiO2@PPy HoMSs exhibit improved microwave absorption compared with BaTiO3/TiO2 HoMSs. In particular, tripled-shelled BaTiO3/TiO2@PPy HoMS has the most excellent absorbing performance. The best reflection loss can reach up to −21.80 dB at 13.34 GHz with a corresponding absorber thickness of only 1.3 mm, and the qualified absorption bandwidth of tripled-shelled BaTiO3/TiO2@PPy HoMS is up to 4.2 GHz. This work paves a new way for the development of high-performance composite microwave absorbing materials. [ABSTRACT FROM AUTHOR]

The kinetics of Fe subsurface dissolution and surface segregation upon annealing Fe/Pd(111) in vacuum/oxygen environment are simulated by the modified Darken model incorporation of oxygen absorption. The simulation results indicate that (1) Fe dissolution takes place only in the subsurface layer upon annealing Fe/Pd(111) in vacuum, and (2) Fe surface segregation takes place by consuming Fe atoms from the FePd3 phase formed in the subsurface layer due to Fe dissolution upon annealing Pd/FePd3/Pd(111) in oxygen environment. These results agree very well with the experimental observations published recently. Meanwhile, a new method for determining the local diffusion coefficient based on the experimental STM observation is proposed by modeling the Fe dissolution kinetics at different annealing temperatures. [ABSTRACT FROM AUTHOR]

Hollow multishelled structure (HoMS) is one of the most promising multifunctional structures. The high complexity of its structure makes the general and controllable synthesis of HoMS rather challenging. By integration of multidisciplinary knowledge, a great achievement in HoMSs has been obtained in the past decade. Especially, the developed sequential templating approach has significantly boomed the progress of HoMS in composition and structure diversity and application area. The implementation of the temporal-spatial ordering in HoMS makes it indispensable in solving the key scientific problems in energy conversion, catalysis and drug delivery areas. Further development in HoMSs with novel intricate structures will bring new understandings. In this review, we systematically introduce the development history of HoMSs, summarize the inspiration inherited from the previous research on hollow structures, and discuss the milestones in the development of HoMSs, with a focus on the sequential templating approach for HoMS fabrication, attractive temporal-spatial ordering property and dynamic smart behavior for advanced applications. We hope to reveal the inherent relationship between the precise synthesis of HoMS and its highly tunable compositional and structural characteristics, and point out its future direction to boost HoMS area further. [ABSTRACT FROM AUTHOR]

The high-temperature oxidation of ZrAl2 upon exposure to pure O2 at 800–950 °C was studied in terms of the oxidation kinetics and the formation mechanism of the oxide layer. The alloy followed parabolic oxidation kinetics, and the activation energy of oxidation was 239 ± 14 kJ/mol. During the early stages of oxidation below 850 °C, a single-layer oxide formed due to the crystallization of the initially formed amorphous oxide layer. A multilayer oxide structure developed at higher temperatures, due to the slightly higher affinity of oxygen for Zr than for Al and the oxidation-induced compositional changes. [ABSTRACT FROM AUTHOR]

TiAlNb-based alloys synthesized at 1223 K (950 °C) by spark plasma sintering were aged at 973 K, 1023 K, 1073 K, and 1123 K (700 °C, 750 °C, 800 °C, and 850 °C), respectively. Phase composition, microstructure, and microhardness of the aged alloys were investigated in this study. Equiaxed O grains and Widmanstätten B2/ β + O laths were formed in the aged alloys, and the microhardness was improved in contrast with the spark plasma-sintered alloy without aging. The microhardness relies largely on the O-phase content, as well as the length and width of the O laths. In particular, complete Widmanstätten B2/ β + O laths, with locally finely dispersed β precipitates, were obtained in the alloy aged at 1073 K (800 °C), and the alloy exhibited the best microhardness performance. Such fine structure is due to the temperature-dependent transformations O→O + B2/ β , O→O + B2/ β , and B2/ β →O. [ABSTRACT FROM AUTHOR]

Data segmentation plays a critical role in performing human activity recognition in the ambient assistant living systems. It is particularly important for complex activity recognition when the events occur in short bursts with attributes of multiple sub-tasks. Although substantial efforts have been made in segmenting the real-time sensor data stream such as static/dynamic window sizing approaches, little has been explored to exploit object semantic for discerning sensor data into multiple threads of activity of daily living. This paper proposes a semantic-based approach for segmenting sensor data series using ontologies to perform terminology box and assertion box reasoning, along with logical rules to infer whether the incoming sensor event is related to a given sequences of the activity. The proposed approach is illustrated using a use-case scenario which conducts semantic segmentation of a real-time sensor data stream to recognise an elderly persons complex activities. [ABSTRACT FROM AUTHOR]

Hollow microspheres of two bismuth oxychlorides, BiOCl and BiOCl, were successfully synthesized using carbonaceous microsphere sacrificial templates. The phase evolution from BiOCl to BiOCl was easily realized by heating the former at 600 °C. With a uniform diameter of about 200 nm, an average shell thickness of 40 nm, and basic nanosheets of <20 nm, the hollow microspheres of both BiOCl and BiOCl showed high visible light photocatalytic activity towards the degradation of Rhodamine B (RhB). Besides the effective photosensitization process and efficient photointroduced carrier separation, the high photocatalytic activity was believed to result from their hollow-structure-dependent large visible light absorption. Moreover, as a chlorine-deficient analogue, the BiOCl hollow spheres possessed a narrower band gap, more dispersive band structure, and higher photocarrier conversion efficiency, which further helped them to exhibit better photocatalytic activity. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Al-induced crystallization (AIC) of amorphous SixGe1–x (a-SixGe1–x) alloys with compositions over the entire range of the isomorphous Si–Ge system has been investigated. The crystallization progress was monitored by dedicated in situ x-ray diffraction analysis while gradually increasing the annealing temperature. Auger sputter-depth profiling was applied to investigate the occurrence of Al-induced layer exchange of the Al and a-SixGe1–x sublayers after complete crystallization. A-SixGe1–x alloys with x < 0.13 and x > 0.41 show largely different AIC behaviors with respect to crystallization rate and possible layer exchange of the Al and a-SixGe1–x sublayers upon crystallization. A thermodynamic model for AIC of a-SixGe1–x alloys is presented, which well explains these experimental observations and thereby demonstrates the dominant role of interface thermodynamics in the AIC process of amorphous semiconductors. The model can be used to predict the AIC behaviors of a-SixGe1–x alloys over the entire composition range at specified annealing temperatures. [ABSTRACT FROM PUBLISHER]

YO nanoplates composed of nanoparticles with both low-energy and high-energy facets exposed have been synthesized via a facile hydrothermal approach and subsequent calcination treatment. The pH value of the reaction solution was observed to play a key role for the formation and even the size- and thickness-control of the nanoplate-like precursor. On calcination at 900 °C for 4 h, the precursors were decomposed into YO with well-maintained flake-like morphology. These YO nanoplates showed obviously improved catalytic CO oxidation activities than commercial and synthesized nanorod YO. Under the UV excitation, flake-like YO:Eu phosphors exhibit strong red photoluminescence emissions, and nanoplates with the reaction temperature of 180 °C, reaction time of 36 h, as well as pH value of 7.4 showed the strongest photoluminescence intensity. This precursor-induced path provided not only a meaningful reference for dimension and size controlled synthesis, but also a potential way to achieve high-active facet exposed materials. [ABSTRACT FROM AUTHOR]

The process of ultrathin Al-induced crystallization of amorphous Si (a-Si) has been investigated by using high-resolution transmission electron microscopy and Auger electron spectroscopic depth profiling. Ultrathin Al overlayers, with thicknesses of 2.0 and 4.5 nm, have been shown to be capable of inducing full crystallization of an a-Si bottom layer as thick as 40 nm at temperatures as low as 320 °C. After full crystallization of a-Si, the Al of the original 2.0-nm Al overlayer completely moved through the Si layer, leaving a high-purity, large-grained crystalline Si layer above it. Such movement of Al also occurs for the originally 4.5-nm Al overlayer, but in this case the crystallized Si layer is relatively fine-grained and contains ~5.0 at.% of residual Al nanocrystals distributed throughout the layer. The observations have been interpreted on the basis of sites available for nucleation of crystalline Si in the microstructure of the Al/Si layer system upon annealing. [ABSTRACT FROM AUTHOR]

Objective: We worked to devise a new way to prevent postoperative persistent air leaks in high-risk pulmonary surgery patients. Methods: From November 1993 to June 2002, 60 patients with difficult to control intraoperative pulmonary air leakage were treated using bioabsorbable polyglycolide felt patches soaked in fibrin glue to cover the leakage site. Results: After application, the felt patch adhered tightly to the lung surface without peeling off, enabling good leakage closure with only 2 ml of fibrin glue used. Air leakage was controlled successfully in 52 (86.7%) of the 60. Four of the 8 patients in whom this method failed to stop air leakage also developed mild pyothorax, with 2 requiring a second operation by video-assisted thoracic surgery. Leakage was eventually controlled in all patients, with no postoperative deaths relating to air leakage. Conclusions: Fibrin-glue-soaked bioabsorbable felt patches effectively seal intraoperative intractable air leaks. Felt patch use may increase the risk of postoperative infection. It should be considered for use on patients with fistulas that cannot be controlled by direct closure or otherwise intraoperatively and who may potentially develop uncontrollable air leakage postoperatively. [ABSTRACT FROM AUTHOR]

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm2-μm with a CE of ~99% at 0.1 C after long-term 400 cycles). [ABSTRACT FROM AUTHOR]

The high-temperature oxidation of ZrAl2 upon exposure to pure O2 at 800–950 °C was studied in terms of the oxidation kinetics and the formation mechanism of the oxide layer. The alloy followed parabolic oxidation kinetics, and the activation energy of oxidation was 239 ± 14 kJ/mol. During the early stages of oxidation below 850 °C, a single-layer oxide formed due to the crystallization of the initially formed amorphous oxide layer. A multilayer oxide structure developed at higher temperatures, due to the slightly higher affinity of oxygen for Zr than for Al and the oxidation-induced compositional changes. [ABSTRACT FROM AUTHOR]