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•Direct observation of H trapping at NbC precipitates was achieved via APT.•NbC increased the reversible/irreversible H trap density and hindered HEDE.•NbC pinned H-dislocation ...atmosphere, reduced Σ3 boundary fraction, and impeded HELP.•NbC weakened the beneficial {111}//ND texture and played a harmful role.•A quantitative model was established to evaluate the density of each type of trap.
The effect of dispersed nanosized spherical NbC precipitates (∼10 nm) on the hydrogen embrittlement (HE) of martensitic steel was investigated by slow strain rate tests, hydrogen permeation tests, atom probe tomography and microstructural examination. HE susceptibility decreases as the amount of NbC increases. NbC plays dual roles in HE. Primarily, NbC alleviates hydrogen accumulation in other areas via hydrogen traps which are induced by NbC directly and increased by the additional grain boundaries resulting from NbC, inhibiting the hydrogen-enhanced decohesion. Moreover, NbC impedes the hydrogen-enhanced localized plasticity by pinning hydrogen-dislocation atmospheres and reducing Σ3 boundary fraction. Secondarily, NbC weakens the beneficial {111}//ND texture, reduces the crack-propagation resistance, and plays a harmful role.
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•Nb micro-alloying significantly improved the HIC resistance of HSLA steel.•Few-nanometer-sized NbC precipitates played a larger role than larger precipitates.•NbC precipitates did ...not initiate cracks and instead reduced intergranular cracking.•Nb increased the reversible/irreversible H trap density and hindered H aggregation.•The effect of Nb is attributed to hydrogen trapping and microstructure optimization.
Hydrogen-induced cracking (HIC) susceptibility tests, hydrogen permeation tests and the electron backscatter diffraction (EBSD) measurements were used to study the effect of Nb on the HIC resistance of the high-strength low-alloy (HSLA) steel. The Nb microalloying significantly improved the HIC resistance and decreased the proportion of intergranular cracks through the hydrogen trapping effect and microstructure optimization. Dispersed nanometer-sized NbC precipitates effectively increased the number of irreversible traps, hindered hydrogen aggregation, and enhanced the resistance to crack initiation and propagation. Moreover, Nb optimized the microstructure by increasing the proportion of the low-angle grain boundaries (LAGBs), refining the prior austenite grain size, decreasing the dislocation density, and changing the distribution of Σ3 boundaries.
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•Nb markedly changed the HIB behavior and played different roles in different stages.•The critical NbC size for blister nucleation at the NbC/matrix interface was ˜226 nm•The adjacent ...medium-sized precipitates induced nucleation at their interspace.•Nb inhibited blister growth via microstructure optimization and providing H traps.•The effect of Nb on the formation of blister on blister was depended on NbC size.
The effect of Nb on hydrogen-induced blistering in pipeline steel was investigated experimentally and computationally. Nb does not change the nucleation mechanism, but influences the nucleation sites and amount: when the individual precipitate independently contributes to retarding or promoting blister nucleation, the critical size of NbC is ˜ 226 nm, which decreases even to 120 nm when two adjacent precipitates are involved. Nb inhibits the blister growth through optimizing microstructure and NbC-induced strong hydrogen traps, showing no strong correlation with NbC size. Few-nanometer-sized NbC inhibits the blister on blister, while the large NbC facilitates the blister on blister through directly nucleating small blister at NbC/matrix interface and promoting dislocation–stress trap nucleation.
The association between the total bilirubin/albumin (B/A) and the all-cause mortality of critically ill patients with acute kidney injury (AKI) remains unclear. This retrospective study aimed to ...investigate the relationship between B/A ratio and mortality in patients with AKI. The clinical data of AKI patients in the Medical Information Mart for Intensive Care III (MIMIC-III) database were retrospectively analyzed. Patients were divided into the low and high B/A groups (B/A less than or equal to 0.25 and B/A > 0.25, respectively). The primary outcome was 28-day all-cause mortality, and the secondary outcomes were 60-day, 1-year and 4-year all-cause mortality. Kaplan-Meier survival curves and Cox proportional risk models were constructed to evaluate the effect of B/A on survival outcomes. The 28-day mortality rates were 18.00% and 25.10% in the low and high B/A groups, respectively (P < 0.001). The Kaplan-Meier analysis showed that patients with higher B/A values had higher all-cause mortality risk (log-rank P < 0.0001). The multivariate Cox proportional risk analysis showed that B/A was an independent risk predictor for death at 28 days, 60 days, 1 year, and 4 years. B/A is an independent risk factor for increased mortality in patients with AKI and may be used as a predictor of clinical outcomes in AKI.
JavaScript has played a crucial role in web development, making it a primary tool for hackers to launch assaults. Although malicious JavaScript detection methods are becoming increasingly effective, ...the existing methods based on feature matching or static word embeddings are difficult to detect different versions and obfuscation of JavaScript code. To solve this problem, we present JSContana, a novel detection method that consists of adaptable context analysis and efficient key feature extraction. The key to our approach is context analysis based on dynamic word embeddings. We convert JavaScript code to syntax unit sequences with detailed information and get the real contextual representation of code by dynamic word embeddings. Furthermore, as a classification module in the method, TextCNN can effectively extract key features. To demonstrate the performance of the method, we have conducted extensive comparison experiments under five-fold cross-validation. Numerical results show that the method achieves 0.990 in AUC-score, and outperforms the state-of-the-art method by up to 3.5%.
Exosomal microRNAs (miRs/miRNAs) have been reported to be associated with cervical cancer. The aim of the present study was to investigate circulating exosomal miRNA as a biomarker for cervical ...cancer diagnosis. In the present study, samples from 6 patients with cervical cancer and 6 healthy control subjects were retrieved for exosomal RNA-sequencing. The results revealed that a total of 39 miRNAs were differentially expressed between patients with cervical cancer and healthy controls (P<0.001; fold-change >2.0). Exosomal miR-125a-5p was further quantified in plasma from 60 subjects, which included 22 healthy individuals and 38 patients with cervical cancer. miR-16a-5p served as the reference miRNA for quantitative PCR analysis of exosomal miR-125a-5p in patients with cervical cancer and healthy individuals. The results revealed that exosomal miR-125a-5p expression levels in the patients with cervical cancer were significantly lower than those in the healthy controls (P<0.001). Receiver operating characteristic (ROC) curve analyses were performed and the results revealed that the level of plasma exosomal miR-125a-5p was a potential marker for differentiating between non-cervical cancer and cervical cancer, with an ROC area under the curve of 0.7129. At the cut-off value of 2.537 for miR-125a-5p, cervical cancer diagnostic sensitivities and specificities were 59.1 and 84.2%, respectively. The present study provides confirmation that exosomal miR-125a-5p could potentially serve as a biomarker for cervical cancer diagnosis. The present study involved only a small number of clinical samples; more samples are required to support the conclusions of the present study. Key words: exosomes, microRNA-125a-5p, cervical cancer, diagnostic marker
The atmospheric corrosion behavior and mechanism of the 7A85 aluminum alloy exposed to the Qingdao industrial-marine atmospheric environment for five years was investigated using the weight-loss ...method, mechanical property analysis, morphology observations, scanning Kelvin probe force microscopy, and corrosion product analysis. The results showed that the mechanical properties of the exposed 7A85 Al alloy deteriorated considerably, which was mainly induced by pitting corrosion and intergranular corrosion. Al2CuMg and Al7Cu2Fe intermetallic particles were the main precipitates in the 7A85 Al alloy, and the particles not only induced a defective film but also acted as cathode phases in the precipitate–matrix galvanic corrosion couple, which led to pitting corrosion initiation during atmospheric corrosion in Qingdao. Moreover, intergranular corrosion initiated and then propagated owing to micro-galvanic corrosion along the grain boundaries.
The mechanism of step-like corrosion pit induced by TiN inclusion in Ti-stabilized interstitial free steel was systematically investigated. There was neither micro-crevice nor local stress in the ...steel matrix adjacent to the TiN inclusion, but a significant Volta potential difference was detected between the conductive TiN and steel matrix. The corrosion pits induced by the TiN inclusion had a step-like structure, composed of an inner pit and a shallow ring-like corroded region (RCR). Three stages, initiation, transition, and propagation stages, involved in the formation of the step-like corrosion pits were observed. The three stages were manifested with the initiation of inner pit, the deepening of inner pit, and RCR formation, respectively. The inner pit was triggered by the Volta potential difference in the initiation stage. In the transition stage, the extreme gradients of H+ and Cl− occurred through the hydrolysis of Fe2+ and electromigration of Cl− in the deepening inner pit. Finally, the extreme gradients of aggressive ions between the inner pit and NaCl bulk solution resulted in the formation of RCR surrounding the inner pit in the propagation stage.
The initial corrosion process of dual phase (DP) steel produced by the continuous annealing process (CAP) in NaCl solution was systematically studied in this paper. The microstructure, nobility of ...the phases, and micro-galvanic corrosion behavior were characterized by scanning electron microscope (SEM), electron backscattered diffraction (EBSD) technique, scanning Kelvin probe force (SKPFM), and electrochemical impedance spectroscopy (EIS). Results indicate that there are two types of martensite, namely fresh martensite (FM) and tempered martensite (TM), embedded in the ferrite matrix. The two types of martensite are surrounded by dislocations and connect to each other as in a chain-like network at the ferrite grain boundary. Both FM and TM can act as a micro-cathode to promote the anodic dissolution of adjacent ferrite matrix since FM is up to 15 mV noble to the ferrite matrix and TM is to 30 mV noble. The initial corrosion process of DP steel can be divided into two stages. The first stage involves an increasing corrosion rate of the steel due to the successive emergence of cathodic TM and FM, while the corrosion rate decreases in the second stage because of the separation of martensite.
•Microwave absorbers are prepared by carbon black and tetrapod-like ZnO whiskers.•Microwave absorption properties depend on concentration and thickness.•Microwave absorption properties are improved ...by addition of T-ZnO whiskers.•The mechanism explains the effects of tetrapod-like ZnO whiskers.
CB/T-ZnO/EP composites were prepared using carbon black (CB) and tetrapod-like ZnO whiskers (T-ZnO) as absorbents and epoxy resin (EP) as binder. The electromagnetic parameters and microwave absorption properties of the composites were measured in the frequency range of 2–18GHz. The influences of absorbents concentration and composites thickness on microwave absorption properties were studied. Results show that the minimum reflection loss for CB/T-ZnO/EP composites is −19.31dB at 10.4GHz and the bandwidth corresponding to reflection loss blow −5dB is 9.68GHz, when the content of CB and T-ZnO whiskers are 7wt% and 13wt%, respectively, and the composites thickness is 3mm. The mechanisms of microwave absorption performance for CB/T-ZnO/EP composites were briefly discussed. It is supposed that CB/T-ZnO/EP composites have the potential to be applied as microwave absorber with high microwave-absorption and light weight.
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