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The agglomeration of polyaniline (PANI) nanofillers in waterborne resins substantially reduces the long-term corrosion resistance of the resins. In this study, we use gum arabic (GA), a biological macromolecule, as a green stabilizer to prepare aqueous dispersions of GA–PANI nanofillers via chemical oxidative polymerization. The highly dispersed GA–PANI nanofillers are incorporated into waterborne epoxy (WEP) matrix and sprayed onto Q235 steel surface. The results show that the GA–PANI nanofillers exhibit excellent dispersion, stability, and compatibility in WEP, as evidenced through transmission electron microscopy and scanning electron microscopy of the cross-sectional morphology, water-absorption tests, and coating adhesion tests. An electrochemical test indicates that the 3.0 wt % GA–PANI/WEP coating displays remarkable corrosion resistance, with the value of impedance modulus in the low-frequency region (|Z|0.01Hz) remaining at 3.372 × 107 Ω cm2 after 60 days of immersion in a 3.5 wt % NaCl solution. This value is almost 1 order of magnitude higher than that of WEP. An X-ray photoelectron spectroscopy test confirms the presence of a corrosion product component on the coating/steel interface. Moreover, the GA–PANI nanofillers extend the penetration route of corrosive species and provide favorable adhesion and anodic protection. [ABSTRACT FROM AUTHOR]

A convenient and ultrasensitive self-powered aptasensing device based on an enzymatic biofuel cell (EBFC) was developed for myoglobin (Mb) detection. The self-powered aptasensor was composed of a functionalized biocathode with carbon nanotube-gold nanoparticle-aptamer (CNT-AuNP-aptamer) and a bioanode with carbon nanotube-gold nanoparticle-glucose oxidase (CNT-AuNP-GOx). To ensure the performance of the self-powered aptasensor, the CNT-AuNP hybrid was selected as the electrode material because of its excellent biocompatibility, superior electrical conductivity, and chemical stability. Meanwhile, aptamer was assembled onto the CNT-AuNP functionalized biocathode through the Au–S bond. When the Mb was present, the aptamer could capture it on the biocathode via specific recognition, and the significant steric hindrance efficiently blocked the electronic transport for the redox probe [Fe-(CN)6]3– at the biocathode, which caused a dramatic decrease of the open-circuit voltage (EOCV). Promisingly, this self-powered aptasensor has particularly high sensitivity for Mb detection over a wide concentration spectrum of 0.1–1 × 104 ng mL–1; the detection limit is as low as 0.011 ng mL–1 (S/N = 3), and the sensor has excellent selectivity, reproducibility, and stability. In addition, the results of the relative standard deviation (RSD) (3.19–5.34%) and recovery (99.27–101.34%) indicated that the aptasensor can be applied to accurately assay Mb within complex biological matrices. As in situ Mb monitoring is of crucial clinical diagnostic significance, this work not only provides an intelligent method for ultrasensitive biosensing of Mb but also is a prospective prototype for a portable and in situ biomedical sensor. [ABSTRACT FROM AUTHOR]

Magnetic core–shell nanomaterial Fe3O4–SiO2–Cu2O/Cu was first successfully synthesized using an economical strategy. Using Fe3O4 as a magnetic center for easy recycling and SiO2 as the connecting layer, Cu elements were evenly and steadily distributed on the surface of the Fe3O4–SiO2–Cu2O/Cu core–shell nanostructure. The magnetic catalyst performed outstanding catalytic reduction activity for 4-nitrophenol (4-NP), and the complete catalytic reduction of 4-NP was achieved within only 5 min. What's more, the catalyst could be well recycled, and the catalytic efficiency remained more than 90% after being reused 24 times. [ABSTRACT FROM AUTHOR]

The influence of sintering pressure on the mechanical properties of bulk titanium carbide (TiC) fabricated through work hardening at high pressure and high temperature is investigated systematically. A series of pure polycrystalline TiC samples are prepared by sintering micrometer-sized TiC powders at a pressure of 9.0–14.0 GPa and a temperature of 1500 °C. These samples are then characterized by various techniques for determining their residual stress, grain size, density, microstructural defects, hardness, and fracture toughness. The results demonstrate that the Vickers hardness HV and the fracture toughness KIC depend strongly on the sintering pressure. It is found that the mechanical properties of the sintered samples improve with increasing sintering pressure. The relative density increases with increasing sintering pressure, reaching near full density at 14.0 GPa. The hardness and fracture toughness of the sample sintered at 1500 °C at 14.0 GPa pressure are 31.2 GPa and 4.2 MPa m1/2, respectively. The high-pressure and high-temperature environment causes severe plastic deformation of the grains, as well as a high density of dislocations, resulting in a dislocation pileup. The latter, together with the production of defects such as sub-boundaries and stacking faults, provides strengthening and stabilizing effects and improves the material hardness. [ABSTRACT FROM AUTHOR]

A novel photocatalytic water splitting device was constructed using economic graphene quantum dots as a photocatalyst and a Ni-based complex [(tpy-CH＝N)2Ni]Cl2 (tpy = terpyridine) as a co-catalyst. Under visible light irradiation and with a bias of −0.1 V vs. NHE, it produced an extremely stable photocurrent density of −9 μA cm−2 for 3 h. [ABSTRACT FROM AUTHOR]

Fluorinated hydroxyapatite-titanium dioxide coating (F-doped HA-TiO2) was deposited in situ onto AZ31 Mg alloy using electrodeposition method. XRD and EDS confirmed the crystal structure and composition of the coating. SEM images showed that the F-doped HA-TiO2 coating on the surface of AZ31 Mg alloy was extremely uniform and the thickness of coating was reflected by the cross-sectional image. Corrosion behavior of the coating modified Mg alloy was tested by electrochemical and immersion experiments. Compared to the corrosion current density (Icorr) of the uncoated AZ31 Mg alloy in Hank's solution, the Icorr of F-doped HA-TiO2 coating was decreased almost 4 orders. The coated AZ31 Mg alloy showed superior biocompatibility, which was strongly demonstrated by the amounts of cells increased in cell culture. The results of hemolysis tests also illustrated that the F-doped HA-TiO2 coating met the requirements of biomedical materials. [ABSTRACT FROM AUTHOR]

The compression behavior and high-pressure strength of alpha silicon nitride (α-Si3N4) at pressures of up to 60 GPa are studied using synchrotron radiation powder diffraction, complemented with first-principles calculations. Compression experiments reveal that a-Si3N4 remains stable under the highest pressure and ambient temperature and has a bulk modulus of K0 = 256.3(±4) GPa, with a pressure derivative of K′0 = 5.6. However, the bulk modulus of experiment is higher than that of calculation (232.5 GPa). The correlation between strength and pressure is confirmed by diffraction peak broadening data. A transition from elastic deformation to plastic deformation of α-Si3N4 at 20 GPa is observed, indicating that α-Si3N4 begins to yield, with yield strength reaching 21 GPa at pressures of up to 20 GPa. A similar phenomenon is observed for MgO, WB3, and c-BC2N. Additionally, theoretical calculations are basically consistent with diffraction experimental results regarding structural stability and mechanical properties. [ABSTRACT FROM AUTHOR]