Ultra-Fine Bainite in Medium-Carbon High-Silicon Bainitic Steel.

The effects of austenitizing and austempering temperatures on the bainite transformation kinetics and the microstructural and mechanical properties of a medium-carbon high-silicon ultra-fine bainitic steel were investigated via dilatometric measurements, microstructural characterization and mechanical tests. It is demonstrated that the optimum austenitizing temperature exists for 0.3 wt.%C ultra-fine bainitic steel. Although the finer austenite grain at 950 °C provides more bainite nuclei site and form finer bainitic ferrite plates, the lower dislocation density in plates and the higher volume fraction of the retained austenite reduces the strength and impact toughness of ultra-fine steel. When the austenitizing temperature exceeds 1000 °C, the true thickness of bainitic ferrite plates and the volume fraction of blocky retained austenite in the bainite microstructure increase significantly with the increases in austenitizing temperature, which do harm to the plasticity and impact toughness. The effect of austempering temperature on the transformation behavior and microstructural morphology of ultra-fine bainite is greater than that of austenitizing temperature. The prior martensite, formed when the austempering temperature below Ms, can refine the bainitic ferrite plates and improve the strength and impact toughness. However, the presence of prior martensite divides the untransformed austenite and inhibits the growth of bainite sheaves, thus prolonging the finishing time of bainite transformation. In addition, prior martensite also strengthens the stability of untransformed austenite though carbon partition and enhances the volume fraction of blocky retained austenite, which reduces the plasticity of ultra-fine bainitic steel. According to the experimental results, the optimum austempering process for 0.3 wt. %C ultra-fine bainitic steel is through austenitization at 1000 °C and austempering at 340 °C.

Inactivated vaccines reduce the risk of liver function abnormality in NAFLD patients with COVID-19: a multi-center retrospective study.

BACKGROUND: Abnormal liver function was frequently observed in nonalcoholic fatty liver disease (NAFLD) patients infected with SARS-CoV-2. Our aim was to explore the effect of SARS-CoV-2 inactivated vaccines on liver function abnormality among NAFLD patients with COVID-19. METHODS: The multi-center retrospective cohort included 517 NAFLD patients with COVID-19 from 1 April to 30 June 2022. Participants who received 2 doses of the vaccine (n = 274) were propensity score matched (PSM) with 243 unvaccinated controls. The primary outcome was liver function abnormality and the secondary outcome was viral shedding duration. Logistic and Cox regression models were used to calculate the odds ratio (OR) and hazard ratio (HR) for the outcomes. Sensitivity analysis was conducted to assess robustness. FINDINGS: PSM identified 171 pairs of vaccinated and unvaccinated patients. Liver function abnormality was less frequent in the vaccinated group (adjusted OR, 0.556 [95% CI (confidence interval), 0.356-0.869], p = 0.010). Additionally, the vaccinated group demonstrated a lower incidence of abnormal bilirubin levels (total bilirubin: adjusted OR, 0.223 [95% CI, 0.072-0.690], p = 0.009; direct bilirubin: adjusted OR, 0.175 [95% CI, 0.080-0.384], p < 0.001) and shorter viral shedding duration (adjusted HR, 0.798 [95% CI, 0.641-0.994], p = 0.044) than the unvaccinated group. Further subgroup analysis revealed similar results, while the sensitivity analyses indicated consistent findings. INTERPRETATION: SARS-CoV-2 vaccination in patients with NAFLD may reduce the risk of liver dysfunction during COVID-19. Furthermore, vaccination demonstrated beneficial effects on viral shedding in the NAFLD population. FUNDING: 23XD1422700, Tszb2023-01, Zdzk2020-10, Zdxk2020-01, 2308085J27 and JLY20180124.

Achieving 2.2 GPa Ultra-High Strength in Low-Alloy Steel Using a Direct Quenching and Partitioning Process.

Advanced high-strength steels (AHSS) have a wide range of applications in equipment safety and lightweight design, and enhancing the strength of AHSS to the ultra-high level of 2 GPa is currently a key focus. In this study, a new process of thermo-mechanical control process followed by direct quenching and partitioning (TMCP-DQP) was developed based on Fe-0.4C-1Mn-0.6Si (wt.%) low-alloy steel, and the effects of microstructure evolution on mechanical properties under TMCP-DQP process and conventional hot rolled quenched and tempered process (HR-QT) were comparatively studied. The results show that the TMCP-DQP process not only shortened the processing steps but also achieved outstanding comprehensive mechanical properties. The TMCP-DQP steel exhibited a tensile strength of 2.23 GPa, accompanied by 11.9% elongation and a Brinell hardness of 624 HBW, with an impact toughness of 28.5 J at -20 °C. In contrast, the HR-QT steel exhibited tensile strengths ranging from 2.16 GPa to 1.7 GPa and elongations between 5.2% and 12.2%. The microstructure of TMCP-DQP steel primarily consisted of lath martensite, containing thin-film retained austenite (RA), nanoscale rod-shaped carbides, and a minor number of nanoscale twins. The volume fraction of RA reached 7.7%, with an average carbon content of 7.1 at.% measured by three-dimensional atom probe tomography (3DAP). Compared with the HR-QT process, the TMCP-DQP process resulted in a finer microstructure, with a prior austenite grain (PAG) size of 11.91 µm, forming packets and blocks with widths of 5.12 µm and 1.63 µm. The TMCP-DQP process achieved the ultra-high strength of low-alloy steel through the synergistic effects of grain refinement, dislocation strengthening, and precipitation strengthening. The dynamic partitioning stage stabilized the RA through carbon enrichment, while the relaxation stage reduced a small portion of the dislocations generated by thermal deformation, and the self-tempering stage eliminated internal stresses, all guaranteeing considerable ductility and toughness. The TMCP-DQP process may offer a means for industries to streamline their manufacturing processes and provide a technological reference for producing 2.2 GPa grade AHSS.

Discussion of the Segregation and Low Hardness of Large-Diameter M3 High-Speed Steel Produced by Spray Forming.

As an advanced near-net-shape processing method in which directly preformed, semi-finished products are created from liquid metals, spray forming has become popular in the development and application of new materials and is supporting industrialization. However, as investigated in this work, the problems of segregation and low hardness exist in the actual industrialization process, particularly for large-diameter M3 high-speed steel. It was here found that the annual ring segregation morphologies were mostly distributed from the edge to 1/2R, with a large number of stripes primarily enriched in C, Mo, and Cr elements, and the degree of segregation was mild. The ring segregation was located at the 1/2R position, where the main elemental enrichments were C, W, Mo, Cr, and V, and the segregation degree was severe. The formation of segregation during deposition is described based on an equilibrium solidification model. A slow cooling rate and heat dissipation from the surface to the inside were judged to be the main factors causing segregation and changes in the carbide morphology. In terms of hardness, with the increase in the quenching temperature to 1230 °C, the tempering hardness increased significantly. The analysis shows that a faster cooling rate in the atomization stage caused the solidified droplets to exhibit rapid solidification characteristics, and there was a higher proportion of MC carbide in the deposited billet. MC carbides cannot be fully dissolved using the conventional heat treatment process, which decreases the C, Cr, Mo, and V contents in the solution and, thus, reduces the secondary hardening capability. The findings show that, when the spray forming process is used to prepare large-diameter materials, it should not be considered a rapid solidification technology simply because of its atomization stage. Moreover, more attention should be paid to the influence of microstructure transformation during atomization and deposition.

CDX2 as a Predictive Biomarker Involved in Immunotherapy Response Suppresses Metastasis through EMT in Colorectal Cancer.

Background: Studies have confirmed that Caudal Type Homeobox 2 (CDX2) plays a tumor suppressor role in colorectal cancer (CRC) and as a prognostic and predictive marker for colorectal cancer. The epithelial to mesenchymal transition (EMT) is a transdifferentiation process, providing migratory and invasive properties to cancer cells during tumor progression. However, the role of CDX2 during the activation of EMT in CRC maintains controversial. Aim: To investigate whether CDX2 is associated with EMT in CRC. Methods: Forty-six CRC patients were included in the study. Expressions of CDX2, E-cadherin, and N-cadherin in all CRC patients were detected by IHC. ROC assays were applied to detect cut-off points for IHC scores to distinguish high and low expressions of CDX2 in 46 CRC samples. The prognostic value of CDX2 was statistically analyzed. MTT, Western blot, invasion, and migration assays in vitro were employed to explore the function of CDX2. Results: We observed that high expressions of CDX2 and E-cadherin as well as low expressions of N-cadherin were significantly correlated with favorable prognosis. The levels of CDX2 protein exhibited a positive associated with E-cadherin while negative correlation with N-cadherin. Then, the low expression of CDX2 and high expression of CA199 in combination are positively related with poor prognosis. Overexpression of CDX2 reduced expression of MMP-2 and diminished cell proliferation, invasion, and migration, while knockdown CDX2 enhanced MMP-2 expression and increased cell proliferation, invasion, and migration in HCT-116 cells. CDX2 was correlated with expression of EMT markers. Overexpression of CDX2 suppressed the EMT markers indicating that CDX2 suppresses CRC cell viability, invasion, and metastasis through inhibiting EMT. Finally, we found that the expression of CDX2 was negatively associated with Th1 cells, macrophages, Th2 cells, cytotoxic cells, T cells, and T helper cells. Conclusions: These results indicated CDX2 as prognostic biomarkers involved in immunotherapy response for CRC. CDX2 loss promotes metastasis in CRC through a CDX2-dependent mechanism.

Encapsulation of atomically dispersed Pt clusters in porous TiO2 for semi-hydrogenation of phenylacetylene.

The synthesis of atomically dispersed metal clusters with strong interaction with the support is attractive for the design of high-efficiency catalysts. Here, we report a multilayered catalyst (1.91%Pt@TiO2), in which atomically dispersed Pt clusters are encapsulated in the porous TiO2. As a result, 1.91%Pt@TiO2 exhibited high activity, selectivity (92.9%), and excellent stability in the semi-hydrogenation of phenylacetylene.

Distance Effect of Ni-Pt Dual Sites for Active Hydrogen Transfer in Tandem Reaction.

Unveiling the distance effect between different sites in multifunctional catalysts remains a major challenge. Herein, we investigate the distance effect by constructing a dual-site distance-controlled tandem catalyst with a five-layered TiO2/Pt/TiO2/Ni/TiO2 tubular nanostructure by template-assisted atomic layer deposition. In this catalyst, the Ni and Pt sites are separated by a porous TiO2 interlayer, and the distance between them can be precisely controlled on the subnanometer scale by altering the thickness of the interlayer, while the inner and outer porous TiO2 layers are designed for structural stability. The catalyst exhibits superior performance for the tandem hydrazine hydrate decomposition to hydrogen and subsequent nitrobenzene hydrogenation when the Ni and Pt site distance is on the subnanometer level. The performance increases with the decrease of the distance and is better than the catalyst without the TiO2 interlayer. Isotopic and kinetic experiments reveal that the distance effect controls the transfer of active hydrogen, which is the rate-determining step of the tandem reaction in a water solvent. Reduced Ti species with oxygen vacancies on the TiO2 interlayer provide the active sites for hydrogen transfer with -Ti-OH surface intermediates via the continuous chemisorption/desorption of water. A smaller distance induces the generation of more active sites for hydrogen transfer and thus higher efficiency in the synergy of Ni and Pt sites. Our work provides new insight for the distance effect of different active sites and the mechanism of intermediate transfer in tandem reactions.

Increasing CO2 differentially affects essential and non-essential amino acid concentration of rice grains grown in cadmium-contaminated soils.

Environmental pollution by both ambient CO2 and heavy metals has been steadily increasing, but we do not know how fluctuating CO2 concentrations influence plant nutrients under high Cd pollution, especially in crops. Here, we studied the effects of elevated CO2 and Cd accumulation on proteins and amino acids in rice under Cd stress. In this pot experiment, we analyzed the amino-acid profile of 20 rice cultivars that accumulate Cd differently; the plants were grown in Cd-containing soils under ambient conditions and elevated CO2 levels. We found that although Cd concentrations appeared to be higher in most cultivars under elevated CO2 than under ambient CO2, the effect was significant only in seven cultivars. Combined exposure to Cd and elevated CO2 strongly decreased rice protein and amino acid profiles, including essential and non-essential amino acids. Under elevated CO2, the ratios of specific amino acids were either higher or lower than the optimal ratios provided by FAO/WHO, suggesting that CO2 may flatten the overall amino-acid profile, leading to an excess in some amino acids and deficiencies in others when the rice is consumed. Thus, Cd-tainted rice limits the concentration of essential amino acids in rice-based diets, and the combination with elevated CO2 further exacerbates the problem.

[Comparison of in vitro release behavior of proanthocyanidins flexible nanoliposomes and general nanoliposomes].

OBJECTIVE: To prepare flexible proanthocyanidins nanoliposomes, and explore the in vitro release behavior of proanthocyanidins flexible nanoliposomes and general nanoliposomes. METHOD: Flexible proanthoeyanidins nanoliposomes were prepared proanthocyanidins using a film dispersion method, characterized by transmission electron microscope, and the in vitro release action was studied in different dissolution mediums using dynamic dialyse method with the content of total phenol as index. RESULT: The in vitro release of both proanthocyanidins flexible nanoliposomes and general nanoliposomes were in accordance with Weibull distribution. CONCLUSION: Proanthocyanidins flexible nanoliposomes without pressure had similar in vitro release behavior with general nanoliposomes.

Using elevated CO2 to increase the biomass of a Sorghum vulgare x Sorghum vulgare var. sudanense hybrid and Trifolium pratense L. and to trigger hyperaccumulation of cesium.

The most important challenge to use phytoremediation is how to improve its efficiency by increasing the accumulation of metals in plants, or by improving key plant biological traits that should enhance metal uptake. In this paper, we used open-top chambers to investigate the effects of elevated CO2 (860 microL L(-1)) on biomass and Cs uptake by a Sorghum vulgare x Sorghum vulgare var. sudanense hybrid and Trifolium pratense L. growing on soils spiked with various levels of cesium (0, 300, 1500 and 3000 mg Cs kg(-1)). The results showed that elevated CO2 not only increased aboveground biomass of the Sorghum and Trifolium species by 32-111%, and by 8-11%, respectively, compared to the ambient CO2 treatment, but also caused more accumulation of Cs by Sorghum species (up to 73%) than Trifolium species (up to 43%). It was speculated that the increase in biomass and the improvement in Cs accumulation ability at elevated CO2 could be related to lowered soil pH values, and changes in number and kind of microorganisms in the rhizospheres of the two tested species. This is the first report of a link among elevated CO2, increased biomass and hyperaccumulation of Cs by Sorghum and Trifolium species.