Search

• After ball milling, the average size of HEA powder composed of large particles and small particles is about 7.1 µm and 1 µm, respectively, and the average size of WC particles is about 368.5 nm. The microstructure consists of FCC phase, HCP-WC phase, Cr 2 O 3 and η(Fe,Co) 3 W 3 C phase. • The interface characteristics of the WC/HEA system include the FCC(111)//HCP (10 1 ‾ 1) interface with stable ionic bond and the interface that reacts due to the formation of (Fe, Co) 3 W 3 C phase. • The density, hardness and fracture toughness values of WC-10 wt% HEA cemented carbide are 14.38 g/cm3, 1988.60 HV, 10.98 MPa m1/2, and the compressive strength values at room temperature and 800 ℃ are 3307 MPa and 1747 MPa, respectively. The thermal conductivities at 50 °C and 650 °C were 38 W(m K)−1 and 30.4 W(m K)−1, respectively. The metal oxides generated by friction behavior at 500 °C have a good effect of reducing friction and antiwear, with an average friction coefficient of 0.365. A new ultra-fine tungsten carbide (WC) cemented carbide was fabricated by spark plasma sintering (SPS), in which the CoCrNiCuFe high entropy alloy (HEA) was used as the binder and was mixed with WC carbide through the mechanical ball milling method. The microstructure of WC-10 wt% HEA composites was investigated through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and differential scanning calorimetry-thermogravimetric analysis (DSC-TG). The results show that the interface characteristics of the WC/HEA system include the FCC(111)//HCP (10 1 ¯ 1) interface with stable ionic bonds and the interface that reacts due to the formation of the (Fe, Co) 3 W 3 C phase. The mechanical properties of WC-10 wt% HEA composites were investigated through the Vickers hardness test, friction and wear tests, and compression test. The WC-10 wt% HEA composites exhibit good fracture toughness and hardness of 10.98 MPa m1/2 and 1988.60 HV 30 , respectively. The compressive strength at room temperature and 800 °C is up to 3307 and 1747 MPa, respectively. The composites exhibited excellent properties attributed to the good wettability of HEA on WC grains and the consequent strengthening effect on the WC/WC interfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous flower-like SnO2/CdSnO3microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination, and the sensing performance was measured when a gas sensor, based on such microstructures, was exposed to various volatile organic compound (VOC) gases. The response value was found to reach as high as 100.1 when the SnO2/CdSnO3sensor was used to detect 100 ppm formaldehyde gas, much larger than those of other tested VOC gases, indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde gas. Meanwhile, the response/recovery process was fast with the response time and recovery time of only 13 and 21 s, respectively. The excellent gas sensing performance derive from the advantages of SnO2/CdSnO3, such as abundant n–n heterojunctions built at the interface, high available specific surface area, abundant porosity, large pore size, and rich reactive oxygen species, as well as joint effects arising from SnO2and CdSnO3, suggesting that such porous flower-like SnO2/CdSnO3microstructures composed of nanosheets have a high potential for developing gas sensors.

Objective Dilated cardiomyopathy (DCM) can cause structural and functional changes in the left ventricle (LV). In this study, we evaluated whether cardiac magnetic resonance tissue-tracking (MR-TT) can be applied to the detection of LV abnormalities in patients with DCM.Methods We used MR-TT to analyze the global peak radial strain (GPRS), global peak circumferential strain (GPCS), and global peak longitudinal strain (GPLS) in every segment of the LV in 23 patients with DCM and 25 controls. The LV ejection fraction was also measured as a function indicator.Results Compared with the controls, the GPRS, GPCS, and GPLS were significantly reduced in patients with DCM, indicating global LV function impairment in all directions. We also identified a significant linear correlation between the GPRS, GPCS, and GPLS and the LV ejection fraction, indicating that LV function relies on coordinated wall motion from all directions. Moreover, we found that patients with DCM had a significantly reduced magnitude of the PRS, PCS, and PLS in most segments at different levels, indicating impaired myocardial function in most LV regions.Conclusions Our results demonstrate that LV myocardial strain in patients with DCM can be sensitively detected by MR-TT (not only the global LV function changes but also the segmental strain), which can help to identify the injured segment at an early stage and guide clinical treatment.

Porous titanium dioxide (TiO2) nanowires were synthesized via a surfactant-free hydrothermal method followed by acid-washing process and calcination. The structures and morphologies of products were characterized by field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) N2adsorption-desorption analyses. The analysis of FESEM suggested the precursor was composed of a vast of uniform nanostructures like wires. The nanowire-like precursor was transformed into the porous nanowire after acid-treatment and calcination at 500°C for 2 h in air. The surface area of as-synthesized TiO2nanowires calculated by BET is 86.4 m2/g. Furthermore, the photocatalytic properties of synthesized porous TiO2nanowires were evaluated through the degradation of methylene blue (MB) and Rhodamine B (RhB). The results clearly suggested that the as-prepared porous TiO2nanowires showed remarkable photocatalytic performance on the degradation of RhB and MB due to their small size of nanocrystallites and the porous naonstructure.

The molecular dynamics (MD) calculation and experimental research methods were used to study the phase transition from onion-like carbon (OLC) with and without a diamond crystal core to nano-polycrystalline diamond (nPCD) under high temperature and high pressure (HTHP) conditions. The results showed that the transformation from OLC to nPCD was mainly a diffusionless transformation at the heating stage and a diffusional transformation at the cooling stage. There were two main paths for diffusionless transformation from the OLC phase to nPCD. The path (PATH1) was that the diamond grew along the graphite crystal direction [002] with the coherent interface formed by the cubic diamond crystal plane (111) parallel to the graphite crystal plane (002). Another path (PATH2) was that the diamond grew along the graphite crystal direction [120] with the coherent interface formed by the cubic diamond crystal plane (11–1) intersecting the graphite crystal plane (002). The initial path of diffusionless transformation of OLC with and without a diamond core was PATH1 and PATH2, respectively. Increasing the PATH1 phase variable can reduce the sintering conditions of the OLC phase to nPCD. The twin boundary content of nPCD can be improved by increasing the grain size consistency of the OLC and the stacking faults density of the OLC structure.

A sea-urchin-like CuO/ZnO porous nanostructure is obtained via a simple solution method followed by a calcination process. There are abundant pores among the resulting nanowires due to the thermal decomposition of copper—zinc hydroxide carbonate. The specific surface area of the as-prepared CuO/ZnO sample is determined as 31.3 m2·g−1. The gas-sensing performance of the sea-urchin-like CuO/ZnO sensor is studied by exposure to volatile organic compound (VOC) vapors. With contrast to a pure porous sea-urchin-like ZnO sensor, the sea-urchin-like CuO/ZnO sensor shows superior gas-sensing behavior for acetone, formaldehyde, methanol, toluene, isopropanol and ethanol. It exhibits a high response of 52.6–100 ppm acetone vapor, with short response/recovery time. This superior sensing behavior is mainly ascribed to the porous nanowire-assembled structure with abundant p—n heterojunctions.

Salinity is a universal environmental stress that causes yield reduction in plants. WRKY33, which has been extensively studied in plant defense against necrotrophic pathogens, has recently been found to be important in salt-responsive pathways. However, the underlying molecular mechanisms controlling the involvement of WRKY33in salt tolerance have not been fully characterized. Here, we explored the function of BcWRKY33A in non-heading Chinese cabbage (NHCC). Under salt stress, BcWRKY33Aexpression is significantly induced in roots. As a nuclear protein, BcWRKY33A has strong transcriptional activation activity. Overexpression of BcWRKY33Aconfers salt tolerance in Arabidopsis, whereas silencing of BcWRKY33Acauses salt sensitivity in NHCC. Furthermore, BcHSFA4A, a protein that interacts with BcWRKY33A, could directly bind to the HSE motif within the promoters of BcZAT12and BcHSP17.6A, which are involved in the plant response to salt stress. Finally, we found that BcWRKY33A could enhance the transcriptional activity of BcHSFA4A and affect its downstream genes (e.g. BcZAT12and BcHSP17.6A), and co-overexpression of BcWRKY33Aand BcHSFA4Acould promote the expression of salt-related genes, suggesting that the regulatory interaction between BcWRKY33A and BcHSFA4A improves salt tolerance in plants. Overall, our results provide insight into the molecular framework of the BcWRKY33A-BcHSFA4A signaling pathway, which also aids in our understanding of the molecular mechanism of salt tolerance in plants.