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The fatigue life and cutting performance of conical pick is essential for the roadheader machine in the excavation engineering. In rock breaking process, the rock structural conditions has a certain influence on the rock breaking and rock damage with roadheader breaking rock. Established the simulation model of conical pick cutting jointed rock to investigate the influence of the rock joint, rock bedding and confining pressure on the cutting performance and fatigue life of conical pick and rock damage. And the MATLAB is applied to solve the difficulty of rock damage statistical analysis. The research results indicated that the cutting force decreases with the rock joint length increasing, the cutting force increases first and decreases with the rock bedding angle increasing, however, the cutting force decreases first and then increases with the confining pressure increasing. The rock damage has a great relationship with the rock joint, rock bedding and confining pressure. The rock damage increases first and decreases then with the rock joint increasing and the rock bedding angle increasing. However, the influence of confining pressure on rock damage is contrary. Meanwhile, the rock fracture volume is positively correlated with damage value. The research results indicated that the rock structural parameters have an obvious influence on conical pick cutting performance and rock damage. [ABSTRACT FROM AUTHOR]

In this study, the small-section profile hat-shaped roll bending part is used as the research object. Aiming at the issue of lacking scientific theory guidance for the bending angle distribution in roll forming, which leads to defects in the forming process and reduces the forming accuracy and quality of the product, a forming angle distribution function with five-boundary condition is proposed. Furthermore, an optimal forming angle distribution method is optimized and obtained on the basis of the distribution interval of forming angle under five-boundary condition determined by the previous research. Then, the generation mechanism of the warpage defect of the hat-shaped roll bending part is simulated and analyzed based on the optimized distribution method for the first time. Through the change of the maximum deviation of z-coordinates, z′, and fluctuation of the edge wave, ∆z, the influence of the forming angle, sheet thickness, and material yield strength on the warpage defect in the roll forming process is studied and verified by experiments. The results show that the stress, strain, fluctuation of the edge wave, and maximum deviation of z-coordinates based on the optimized distribution method are smaller than those of other distribution methods, showing its superiority in forming process. In addition, the peak longitudinal strain increases as the forming angle increases and the warpage decreases as the sheet thickness and yield strength increase. [ABSTRACT FROM AUTHOR]

Cationic iron (III) tetrakis-5, 10, 15, 20-( N-methyl-4-pyridyl) porphyrin (Fe IIITMPyP) was intercalated into layered semiconductor KNb 3O 8 by ion-exchange method. The target product was characterized by XRD, Fourier transform infrared, UV–vis, and TGA. Fe IIITMPyP forms an inclined monolayer between Nb 3O 8− nanosheets and endues the nanocomposite with excellent electrochemical catalytic activities. The target nanocomposite modified glass carbon electrode shows good electrocatalytic activities for the oxidation of ascorbic acid (AA); the catalytic mechanism was proposed. Differential pulse voltammetric technique was used for detection of AA in neutral aqueous solution; a detection limit of 4.2 × 10 −5 M was obtained, and the modified electrode showed good reproducibility in electrochemical detection. [ABSTRACT FROM AUTHOR]

In this paper, by a simple hydrothermal method vertically aligned ZnO nanorod arrays were grown on the carbon fiber paper (CFP) and then through a facile chemical bath deposition method CuO nanosheets were loaded on ZnO nanorod arrays, following by thermal spraying method, carboxylated carbon nanotubes (CCNTs) were successfully integrated with CuO/ZnO@CFP to form a binder-free CuO/ZnO-CCNT@CFP sensor. The sensor shows enhanced sensing activity for baicalein and luteolin determination due to the improved structural integration and synergism of different electrode material components. Remarkably, the CuO/ZnO-CCNT@CFP sensor showed good linear relationships over wide concentration ranges of 0.03–0.70 µM and 0.70–20 µM for baicalein and 0.03–0.45 µM and 0.45–8.5 µM for luteolin detection, with the detection limits of 1.7 nM for baicalein and 0.5 nM for luteolin, respectively. More importantly, the CuO/ZnO-CCNT@CFP sensor was utilized in the simultaneous determination of baicalein and luteolin, delivering linear ranges of 0.4–14 µM (baicalein) and 0.2–6 µM (luteolin) with the limit of detection of 0.05 µM and 0.03 µM, respectively. In addition, the developed CuO/ZnO-CCNT@CFP electrode was further investigated to detect baicalein and luteolin in traditional herbal medicine samples, showing satisfied results in comparison with analytic results from high performance liquid chromatography. [ABSTRACT FROM AUTHOR]

There is an urgent need for the rapid and simultaneous detection of multiple analytes present in a sample matrix. Here, a multiplex immunochromatographic test (multi-ICT) was developed that successfully allowed for the rapid and simultaneous detection of four major nitrofuran metabolites, i.e., 3-amino-2-oxazolidinone (AOZ), semicarbazide (SEM), 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD), in fish samples. Four different antigens were separately immobilized in four test lines on a nitrocellulose membrane. Goat anti-mouse immunoglobulin (IgG) was used as a control. Sensitive and specific monoclonal antibodies (mAbs) that recognize the corresponding antigens were selected for the assay, and no cross-reactivity between the antibodies in the detection assay was observed. The free analytes in samples or standards were pre-incubated with freeze-dried mAb-gold conjugates to improve the sensitivity of the detection assay. The multi-ICT detection was accomplished in less than 15 min by the naked eye. The cutoff values for the strip test were 0.5 ng/mL for AOZ and 0.75 ng/mL for AHD, SEM, and AMOZ, which were all below the maximum residue levels set by the European Union and China. A high degree of consistency was observed between the multi-ICT method and commercially available enzyme-linked immunosorbent assay (ELISA) kits using spiked, incurred, and 'blind' fish samples, indicating the accuracy, reproducibility, and reliability of the novel test strip. This newly developed multi-ICT strip assay is suitable for the rapid and high-throughput screening of four nitrofuran metabolites in fish samples on-site, with no treatment or devices required. [ABSTRACT FROM AUTHOR]

In this work, we report a novel nonenzymatic glucose detection base on the use of Au (111)-like/SiO2 indium tin oxide (ITO) electrode. First, the ordered SiO2-cavity array was fabricated on the ITO electrodes via the ordered polystyrene spheres (PS) templates. Secondly, the nucleation stage of Au NPs was generated by an electrochemical seeding growth method. As a matter of fact, A u C l 4 - could be electrodeposited on the as-prepared Au seeds in a subsequent cyclic voltammetry, the raspberry-like Au NPs were formed with major facet of (111). The size and density of raspberry-like Au NPs could be successfully controlled. The as-prepared electrode showed good electrochemical performance for glucose oxidation with the linear range from 50 μM to 1.5 mM (R = 0.9995), a low detection limit of 12 μM, and good selectivity of the interferences of AA and UA. The raspberry-like Au (111)-like/SiO2 ITO electrode might become an enzyme-free glucose sensor with long-term stability and good reproducibility. [ABSTRACT FROM AUTHOR]