Austenitizing temperature is one decisive factor for the mechanical properties of medium carbon martensitic stainless steels (MCMSSs). In the present work, the effects of austenitizing temperature ...(1000, 1020, 1040 and 1060 °C) on the microstructure and mechanical properties of MCMSSs containing metastable retained austenite (RA) were investigated by means of electron microscopy, X-ray diffraction (XRD), as well as tensile and impact toughness tests. Results suggest that the microstructure including an area fraction of undissolved M
C
, carbon and chromium content in matrix, prior austenite grain size (PAGS), fraction and composition of RA in studied MCMSSs varies with employed austenitizing temperature. By optimizing austenitizing temperature (1060 °C for 40 min) and tempering (250 °C for 30 min) heat treatments, the MCMSS demonstrates excellent mechanical properties with the ultimate tensile strength of 1740 ± 8 MPa, a yield strength of 1237 ± 19 MPa, total elongation (ductility) of 10.3 ± 0.7% and impact toughness of 94.6 ± 8.0 Jcm
at room temperature. The increased ductility of alloys is mainly attributed to the RA with a suitable stability via a transformation-induced plasticity (TRIP) effect, and a matrix containing reduced carbon and chromium content. However, the impact toughness of MCMSSs largely depends on M
C
carbides.
An in‐house designed transmission X‐ray microscopy (TXM) instrument has been developed and commissioned at beamline BL18B of the Shanghai Synchrotron Radiation Facility (SSRF). BL18B is a hard (5–14 ...keV) X‐ray bending‐magnet beamline recently built with sub‐20 nm spatial resolution in TXM. There are two kinds of resolution mode: one based on using a high‐resolution‐based scintillator‐lens‐coupled camera, and the other on using a medium‐resolution‐based X‐ray sCMOS camera. Here, a demonstration of full‐field hard X‐ray nano‐tomography for high‐Z material samples (e.g. Au particles, battery particles) and low‐Z material samples (e.g. SiO2 powders) is presented for both resolution modes. Sub‐50 nm to 100 nm resolution in three dimensions (3D) has been achieved. These results represent the ability of 3D non‐destructive characterization with nano‐scale spatial resolution for scientific applications in many research fields.
A demonstration of full‐field hard X‐ray nano‐tomography for high‐ and low‐Z material samples is presented for the two TXM resolution modes developed at beamline BL18B at SSRF.
The structural and chemical evolution of battery electrodes at the nanoscale plays an important role in affecting the cell performance. Nano‐resolution X‐ray microscopy has been demonstrated as a ...powerful technique for characterizing the evolution of battery electrodes under operating conditions with sensitivity to their morphology, compositional distribution and redox heterogeneity. In real‐world batteries, the electrode could deform upon battery operation, causing challenges for the image registration which is necessary for several experimental modalities, e.g. XANES imaging. To address this challenge, this work develops a deep‐learning‐based method for automatic particle identification and tracking. This approach was not only able to facilitate image registration with good robustness but also allowed quantification of the degree of sample deformation. The effectiveness of the method was first demonstrated using synthetic datasets with known ground truth. The method was then applied to an experimental dataset collected on an operating lithium battery cell, revealing a high degree of intra‐ and interparticle chemical complexity in operating batteries.
A deep‐learning‐assisted image registration method is demonstrated for in situ X‐ray nano‐imaging of a composite battery cathode electrode with deformation. The method handles the challenges associated with electrode deformation by identifying and tracking isolated cathode particles separately. This approach could facilitate analysis of the correlation between intraparticle reaction heterogeneity and electrode deformation, which collectively affect the performance of real‐world batteries.
Serine/threonine/tyrosine kinase 1 (STYK1) is known to be involved in tumor progression. However, its molecular role and mechanism in hepatocellular carcinoma (HCC) remains unknown. We evaluated the ...effect of STYK1 expression in HCC tissues and investigated the underlying mechanisms associated with progression. HCC tissues expressed greater levels of STYK1 than paired non-tumor tissues. Patients with HCC expressing low levels of STYK1 showed both, greater disease-free (p < 0.0001) and overall (p = 0.0004) survival than those expressing high levels of STYK1. Decreased expression of STYK1 was significantly associated with decreased cell proliferation, reduced migratory capability, and reduced invasive capability. Overexpression of STYK1 was significantly associated with increased cell proliferation, migratory capability, and invasive capability in vitro, as well as increased volume of tumor, weight of tumor, and number of pulmonary metastases in vivo. Furthermore, STYK1's mechanism of promoting cancer cell mobility and epithelial-mesenchymal transition (EMT) was found to be via the MEK/ERK and PI3K/AKT pathways, resulting in increased expression of mesenchymal protein markers: snail, fibronectin, and vimentin, and decreased E-cadherin expression. Our results suggest that STYK1 acts as an oncogene by inducing cell invasion and EMT via the MEK/ERK and PI3K/AKT signaling pathways and it therefore may be a potential therapeutic target in HCC.
Fiber-based thermoelectric materials and devices have the characteristics of light-weight, stability, and flexibility, which can be used in wearable electronics, attracting the wide attention of ...researchers. In this work, we present a review of state-of-the-art fiber-based thermoelectric material fabrication, device assembling, and its potential applications in temperature sensing, thermoelectric generation, and temperature management. In this mini review, we also shine some light on the potential application in the next generation of wearable electronics, and discuss the challenges and opportunities.
Rodents are used extensively as animal models for the preclinical investigation of microvascular‐related diseases. However, motion artifacts in currently available imaging methods preclude real‐time ...observation of microvessels in vivo. In this paper, a pixel temporal averaging (PTA) method that enables real‐time imaging of microvessels in the mouse brain in vivo is described. Experiments using live mice demonstrated that PTA efficiently eliminated motion artifacts and random noise, resulting in significant improvements in contrast‐to‐noise ratio. The time needed for image reconstruction using PTA with a normal computer was 250 ms, highlighting the capability of the PTA method for real‐time angiography. In addition, experiments with less than one‐quarter of photon flux in conventional angiography verified that motion artifacts and random noise were suppressed and microvessels were successfully identified using PTA, whereas conventional temporal subtraction and averaging methods were ineffective. Experiments performed with an X‐ray tube verified that the PTA method could also be successfully applied to microvessel imaging of the mouse brain using a laboratory X‐ray source. In conclusion, the proposed PTA method may facilitate the real‐time investigation of cerebral microvascular‐related diseases using small animal models.
A pixel temporal averaging method is developed to eliminate motion artifacts and random noises aiming at real‐time and in vivo radiology of mouse cerebral microvessels.
BackgroundFull-field transmission X-ray microscopy (TXM)–X-ray absorption near-edge structural (XANES) (TXM-XANES) is an imaging method that combines TXM and XANES. By measuring the TXM images of ...multiple energy points before and after the K-edge of the element of interest, the distribution of elemental chemical states in the sample can be determined. Conventional TXM-XANES data requires the acquisition of images and background images at each energy point, which results in a large data volume and extended acquisition time. At the nanoscale, the instability of the mechanical structure and the movement of the sample may impact the TXM-XANES data analysis.PurposeThis study aims to use machine learning methods to achieve background-image sequence prediction modeling using only two spectral background images to reduce the data volume and shorten the acquisition time.MethodsMachine learning, polynomial regression, and linear interpolation were used to generate background image sequences. A prediction model of the c
We report the observation of persistent chemical gradient on rock-salt Li1.3Nb0.3Mn0.4O2 single crystals transforming through a second-order reaction and reveal the dominating effect of local ...chemistry on Li diffusion within the percolated network. By using advanced 2D and 3D nanoscale X-ray spectro-microscopy on well-formed crystal samples, our study visualizes the mesoscale chemical distribution as a function of the state of charge at the subparticle level. We further reveal the presence of thermodynamically favorable short-range ordering of Nb-cation-only (Nb6) and Nb-cation-enriched (MnNb5) configurations, which promote non-equilibrium diffusion pathways and the expansive chemical heterogeneity observed on LixNb0.3Mn0.4O2 particles. The present study utilizes large single crystals to eliminate the influence of kinetic factors such as particle-size distribution, crystal facet, grain boundary, and strain, allowing us to clearly demonstrate the strong correlation between a material's structural defects and chemical propagation and its crucial impact on electrode performance and stability.
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•Subparticle-level chemical heterogeneity exists in delithiated oxide•Short-range ordering is thermodynamically favorable in rock salts•Strong correlation between structural defects and chemical propagation is demonstrated
A new class of disordered rock-salt oxides is capable of delivering energy density much higher than those of current lithium (Li)-ion battery cathodes. Theoretical calculation predicted facile Li diffusion enabled by the formation of percolating network in the Li-excess oxides; however, fundamental knowledge regarding how Li diffuses within the network and what affects this process is lacking. Here, we provide experimental evidence of Li-diffusion pathways at multiple length scales and report the dominating effect of local chemistry on Li mobility. We reveal that the existence of local cation ordering redirects Li movement through non-equilibrium pathways and leads to the unusual persistent chemical heterogeneity observed at the subparticle level. The strong correlation between structural defects and the propagation of chemical reaction is clearly demonstrated, providing essential insights needed for further design and development of these cathode materials.
Cathode performance is generally considered the bottleneck of further increasing energy in Li-ion battery technology. Novel Li-rich disordered rock salts have a lithium storage capacity much higher than those of the current cathodes, making them attractive as next-generation materials. The path to commercialization, however, is hindered by the lack of fundamental understanding in a material's properties and behavior. Here, we show how structural defects can be used to influence Li diffusion and kinetic properties, providing critical insights needed for the design and optimization of these new materials.
BackgroundDynamic micro-computed tomography (micro-CT) using monochromatic X-ray offers higher density resolution and lower radiation damage compared to that using white X-ray, however balancing its ...imaging spatial and temporal resolution is challenging. Currently, the reported highest temporal resolution of monochromatic X-ray dynamic micro-CT is 13.3 Hz with a detector effective pixel size of 5 μm.PurposeThis study aims to develop a monochromatic X-ray dynamic micro-CT system with a higher spatial and temporal resolution to meet the experimental needs of the fast X-ray imaging beamline (BL16U2) users at Shanghai Synchrotron Radiation Facility (SSRF).MethodsFirstly, an experimental system of dynamic micro-CT with the high flux density monochromatic X-ray from an undulator source was established by combination of a high-speed rotary stage and a large numerical aperture triple-lens fast X-ray imaging detection system on the BL16U2 beamline at SSRF. Then, a demonstration experiment with a fast-foaming polyureth
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