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Exfoliation corrosion (EFC) has rarely been reported for wrought magnesium alloys. Enhanced EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained skins. The microstructure and corrosion products were investigated using optical microscopy, scanning electron microscopy, electron backscattered diffraction, X-ray diffraction, and Fourier transform infrared spectrometry. The corrosion behavior was analyzed using electrochemical polarization, electrochemical impedance spectroscopy, and scanning Kelvin probe techniques. The results indicated that the surface of Mg–1Li–1Ca, with the superficial layer removed, was more susceptible to EFC. A linear correlation between grain boundary density and corrosion resistance was established. Additionally, the influence of factors such as grain size, intermetallic compounds, different alloy surfaces, and corrosion products on EFC were discussed, and the corresponding EFC mechanism was clarified.

Biomimetic graphene−epoxy composite coating was fabricated with a “brick and mud” structure via a spin-coating strategy. Imidazolium-based ionic liquids modified graphene (GI) was synthesized to improve the interfacial compatibility between the graphene (G) layers and epoxy resin. The surface morphology and chemical structures were observed and analyzed through scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) as well as Fourier transform infrared spectroscopy (FTIR). The thermal imager was used to record the temperature change on the surface. The surface resistivity and thermal conductivity of the coating were determined via volumetric surface area resistivity tester and laser flash method, respectively. The corrosion resistance was investigated through electrochemical impedance spectroscopy (EIS) and salt spray testing. The GI layers in the composite coating exhibited a near-parallel orientation, which led to improved heat transfer and electrostatic dissipative efficiency. The through-plane thermal conductivity and surface resistivity were 0.77 W·m−1·K−1and 1.6×106Ω·cm, respectively. Electrochemical impedance spectroscopy tests revealed that the low-frequency modulus of the coating reached 6.76×1010Ω·cm2after 40 d of immersion, which was about two orders of the magnitude higher than that of the pure epoxy coating, showing a superior corrosion resistance.

The impact of the anodic second phase, Mg41Nd5in as-extruded Mg–4Li-3Nd-0.2Zn alloy was first reported as a candidate anode material for primary Mg-air batteries. Solid solution treatment of Mg–4Li-3Nd-0.2Zn was conducted at 400, 450, and 500 °C for 8 h. The electrochemical behaviour and discharge performance were investigated using microstructural characterization, electrochemical measurements, and discharge tests. The results indicated that solid solution treatment led to increased grain size and reduced volume fraction of the anodic second phase (Mg41Nd5) with a uniform distribution. In turn, the anode electrochemical activity was promoted, and the bulk effect was reduced. The anode efficiency and comparison capacity were significantly improved. At 5 mA cm−2, the average discharge voltage reached as high as 1.45 V with a utilization efficiency of 61.29%, and a discharge capacity of 1358.98 mAh·g−1for the solid solution-treated sample at 450 °C, making it the excellent candidate anode material for Mg-air batteries.

• A curcumin loaded coating with flake structure prepared on AZ31 alloy. • Coating displays anticorrosion and antibacterial ability with low cytotoxicity. • High photothermal conversion efficiency and photothermal antibacterial coating on AZ31 alloy surface. • A new double antibacterial coating preparation method for the Mg bone implants is provided. • β -CD and SA used to enhance bioavailability of curcumin and binding force. It is a challenging task to prepare a coating on Mg alloys for desirable corrosion resistance, good antibacterial ability and biocompatibility. In this research work, an in-situ Mg(OH) 2 coating incorporated with sodium alginate (SA) and β -cyclodextrin (β -CD)@curcumin (Cur) was formed on the surface of micro arc oxidation (MAO) coated AZ31 alloy via a low temperature hydrothermal method. Characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR) and scanning electron microscope (SEM) were employed to characterize the chemical composition and surface morphology of the coatings. The corrosion protection ability of the coatings was monitored via electrochemical polarization, hydrogen evolution and immersion tests. Photothermal antibacterial ability and cytocompatibility of the coatings were evaluated by plate counting method under the irradiation of 808 nm-near infrared light, in vitro cytotoxicity tests (MTT) and live/dead cell staining. The results indicate that a chelation of the organic molecules led to the formation of a MAO/(β -CD@Cur)-SA-Mg(OH) 2 coating with excellent corrosion protection, multi- antibacterial ability and almost no toxicity to the cells. Especially, the coating provided photothermal performance through the light absorption of Cur, which was encapsulated by β -CD to improve its bioavailability. SA enhanced the binding force between the drug and the substrate. This novel coating designated the potential application on bioabsorbable magnesium alloys. [ABSTRACT FROM AUTHOR]

Surgical failures, caused by postoperative infections of bone implants, are commonly met, which cannot be treated precisely with intravenous antibiotics. Photothermal therapy (PTT) and photodynamic therapy (PDT) have attracted widespread attention due to their non-invasive antibacterial effects on tissues and no bacterial resistance, which may be an excellent approach to solve infections related to bone implants for biodegradable magnesium alloys. Herein, a sodium copper chlorophyllin (SCC) with a porphyrin ring induced Ca–P coating was prepared on AZ31 magnesium alloy via layer-by-layer (LbL) assembly. The morphology and composition of the samples were characterized through field emission scanning electron microscope (FE-SEM) with affiliated energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and Fourier infrared spectrometer (FTIR) and X-ray photoelectron spectrometer (XPS) as well. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and hydrogen evolution experiments were employed to evaluate the corrosion behavior of the samples. Atomic absorption spectrophotometer was used to measure Cu elemental content of different immersion periods. Cytocompatibility and antibacterial performance of the coatings were probed using in vitrocytotoxicity tests (MTT assay), live/dead cell staining and plate counting method. The results showed that the obtained (Ca–P/SCC)10coating exhibited good corrosion resistance, antimicrobial activity (especially under 808 nm irradiation) and biocompatibility. The antibacterial rates for E. coliand S. aureuswere 99.9% and 99.8%, respectively; and the photothermal conversion efficiency was as high as 42.1%. Triple antibacterial mechanisms including photodynamic, photothermal reactions and copper-ions release were proposed. This coating exhibited a promising application for biodegradable magnesium alloys.

The influence of intermetallic Al-Mn particles on the corrosion behavior of in-situ formed Mg-Al layered double hydroxide (Mg-Al-CO32--LDH) steam coating on AZ31 Mg alloy was investigated. The alloy was pretreated with H3PO4, HCl, HNO3or citric acid (CA), followed by hydrothermal treatment, for the fabrication of Mg-Al-LDH coating. The microstructure, composition and corrosion resistance of the coated samples were investigated. The results showed that the surface area fraction of Al-Mn phase exposed on the surface of the alloy was significantly increased after CA pretreatment, which promotes the growth of the Mg-Al-LDH steam coating. Further, the LDH-coated alloy pretreated with CA possessed the most compact surface and the maximum coating thickness among all the coatings. The corrosion current density of the coated alloy was decreased by three orders of magnitude as compared to that of the bare alloy.

In situ formation mechanism of steam Mg–Al layered double hydroxide (Mg–Al–CO3-LDH) coatings on AZ31 and AM30 alloys was compared in presence of NaOH aqueous solution. The microstructure and elemental composition of the obtained coatings were analyzed using SEM, EDS, XRD and FTIR. The corrosion resistance of the coated samples was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and salt spray test. The results indicated that the addition of NaOH significantly influenced the morphology as well as the thickness of the prepared LDH coating. The effect of different Al–Mn phase contents of AZ31 and AM30 alloy on the growth mechanism of the LDH coatings was discussed. The addition of 0.01 M NaOH promoted the growth of the LDH coating on AZ31 and AM30 alloys. The AM30-NaOH-0.01 sample possessed the most compact and uniform surfaces as well as the maximum thickness. The corrosion current density of the samples was reduced by three orders of magnitude compared to their substrates. It was revealed that the addition of a moderate amount of NaOH in the steam would raise the pH level, which would benefit the dissolution of the aluminum phase and promote the growth of LDH coating.

Zinc ferrite loaded with reduced graphene oxide (ZnFe2O4/rGO) and zinc ferrite (ZnFe2O4) catalysts were synthesized viaa one-spot method. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy, surface photovoltage spectroscopy and X-ray photoelectron spectroscopy. Results revealed that the as-synthesized ZnFe2O4/rGO and ZnFe2O4particles were cubic spinel-type ZnFe2O4with space group number of Fd3m, and that their average diameters were 7.4 and 7.0 nm, respectively. The photocatalytic results indicated that the ZnFe2O4/rGO hybrid catalyst possesses higher activity than that of the single ZnFe2O4component under visible-light irradiation. More importantly, the ZnFe2O4/rGO catalyst could recognize ammonia from an organic pollutant-ammonia mixed solution and selectively degrade ammonia and nitrogen gas based on the coordination recognition between Zn cations on ZnFe2O4and ammonia in solution. Fourier-transform infrared, Raman and X-ray photoelectron spectra confirmed that ammonia was selectively adsorbed on ZnFe2O4particles. The shifts of Zn 2p3/2 and Zn 2p1/2 binding energies confirmed the coordination between Zn cations and ammonia. The surface photovoltage spectra revealed that the photo-generated holes moved to the surface of ZnFe2O4particles upon incident visible-light irradiation, and degraded ammonia adsorbed on the catalyst surface. These findings will encourage more investigations of photocatalysis based on coordination recognition.

Mn-based cathode material Li1.20Mn0.52Ni0.20Co0.08O2was proposed and ameliorated by surface-coating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and doping Ga3+. X-ray diffraction and high-resolution transmission electron microscopy studies revealed that part of Ga3+replacing the Ni site could reduce the Li+/Ni2+mixing by forming a well-ordered layered structure and a homogeneous coating layer of PEDOT:PSS is covered on the surface of Li1.20Mn0.52Ni0.19Co0.08Ga0.01O2. The results of the electrochemical studies demonstrated the higher initial charging–discharging Coulombic efficiency, and outstanding rate capabilities and cyclic performance were obtained for the PEDOT:PSS-covered and Ga3+-doped samples. Especially, 2 wt % PEDOT:PSS-coated Li1.20Mn0.52Ni0.19Co0.08Ga0.01O2delivered 38.3 mAh g–1, which is larger than the pristine cathode at a 5C high rate. Meanwhile, it could retain 189.6 mAh g–1(90.3% of its initial discharge capacity at 45 °C) after 300 cycles with a 1C rate, while the pristine cathode only delivered 149.7 mAh g–1with 80.7% cycling retention left. The results strongly suggested that such PEDOT:PSS-coated and Ga3+-doped Mn-based layered structure materials demonstrated high potential as a cathode candidate especially for high-energy applications.

The physiological environment of the human body is an extremely complex system, containing not only inorganic ions but also organic molecules; thus it is necessary to understand the influences of the different functional groups of three six-carbon small organic molecules (glucose (Glu), vitamin C (Vc), and citric acid (CA)) on the degradation mechanisms of pure magnesium (Mg). Electrochemical polarization and impedance spectroscopy, hydrogen evolution rates, and pH monitoring tests were used to characterize the degradation behaviors of pure Mg in 0.9 ​wt% NaCl and phosphate-buffered saline (PBS) solutions. Using scanning electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, the compositions, phase structures, and morphologies of the degradation products were investigated. Results indicated that Glu enhanced the biodegradation rate of pure Mg in 0.9 ​wt% NaCl solution, whereas Vc and CA slowed down their biodegradation rate. In the PBS solution, both Glu and Vc reduced the biodegradation rate of pure Mg, while CA accelerated its initial biodegradation and retarded its long-term biodegradation. In addition, Raman spectroscopy demonstrated the formation of Mg-(gluconate, l-threonic acid, oxalate, and citrate) on the pure Mg. Plausible biodegradation mechanisms of pure Mg are proposed regarding the influences of Glu, Vc, and CA.

Biomophic titanium oxide with nanocrystalline was successfully synthesized using napkin template, which everybody uses. Unique biomorphic microstructures were characterized by field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption techniques. TiO2 material was characterized by repetitious networks consisting of the fibers with diameter of 1-6μm. The results showed that the products were composed by polycrystalline TiO2 nanoparticles with diameter of ca. 5-8 nm and the high specific surface area (81.0 m2·g-1) of sample,which were believed to result from the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and the Brunauer-Emmett-Teller (BET) method. While the concentration of acid black solution was 20 mg/L, catalyst amount 0.1 g/L, the reaction had a higher photocatalytic performance following irradiation with a visible light by xenon lamp, the decoloring rate can reach over 100% after 250 min.

Negative-charged PS microspheres were prepared through emulsifier-free emulsion polymerization method. High-quality PS colloidal crystals were obtained via the horizontal deposition method. Hierarchically ordered macroporous CeO2 sheets were fabricated on fluorine-doped tin oxide (FTO) substrates using PS colloidal crystals as template by a continuous infiltration process. The structure and morphology of the products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption-desorption. The characterized results showed that macroporous CeO2 sheets replicated well three-dimensionally (3D) ordered structure derived from PS colloidal crystals template and possessed a relatively large specific surface area. Moreover, the synthesized hierarchical CeO2 sheets showed the highest photocatalytic activity under solar irradiation and also exhibited remarkable ability to remove methylene blue, suggesting they are promising catalyst for wastewater treatment.

Biomophic ceria with nanocrystalline was successfully synthesized using crucian fish scales as template. Unique biomorphic microstructures were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption technique. The obtained ceria material shows the repetitious biomimetic structure consisting of sheet with thickness of ca. 80-100 nm and nanopores which had 2-10 nm apertures. The surface oxygen activity of fish scale-templated CeO2 was enhanced revealed by hydrogen temperature-programmed reduction (H2-TPR) mesurements, because of the higher surface area (113.5 m2/g) and smaller particle size (average of 8.2 nm). Those detailed investigation could infer that the biotemplate product exhibit better catalytic activity in CO oxidation reaction.

Expanded graphite-based carbon/carbon composite (EGC) electrode was prepared by compressed expanded graphite impregnated in sucrose-phosphoric acid solution. The porous texture and microstructure of the composite were analyzed by physical adsorption measurements of N2 adsorption at 77K and SEM. The influence of electrolytic conditions on the phenol degradation was investigated. The results indicated that the EGC electrode was comprised of a graphite framework coated by a thin layer of activated carbon. It could be used as an anode to degrade phenol effectively in the solution by electrochemical oxidation. The data in the experiment showed that the removal efficiency of phenol increased with lowering the initial phenol concentration, increasing the current density and electrolyte concentration.

Hierarchical porous ceria with nanocrystalline was successfully synthesized using filter paper as biotemplate. Unique biomorphic microstructures were characterized by Field Emission Scanning Electron Microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption technique. The obtained ceria material showed the repetitious biomimetic structure consisting of fibre with diameter of ca. 1-3 μm and nanopores which had 2-4 nm apertures. The small crystallite diameter (6-8 nm) and the high specific surface area (71.3 m2·g-1) of porous CeO2 were measured by wide-angle X-ray Diffraction (XRD), high resolution TEM (HRTEM) and the BET method. While the concentration of acid fuchsine was 20 mg/L, the porous sample had a higher decoloring rate in a shorter time than others. The decoloring rate can reach 100% after 200 min.

Hierarchical porous TiO2 fibre was successfully synthesized using cotton as template. Microstructures of product were characterized by Field Emission Scanning Electron Microscope (FESEM), nitrogen absorption-desorption technique and transmission electron microscopy (TEM). Titanium oxide material was characterized by repetitious networks consisting of the fibres with diameter of ca. 3-8 μm. The results showed that the products were composed 2-5 nm piled pores stacked by polycrystalline TiO2 nanoparticles. The small crystallite diameter (6-10 nm) and the high specific surface area (83.7 m2·g-1) of sample was believed to be resulted from wide-angle X-ray Diffraction (XRD), high resolution TEM (HRTEM) and the BET method. While the concentration of methylthionine chloride solution was 20 mg/L, catalyst amount 0.1 g/L, the reaction had a higher decoloring rate following irradiation with a UV light source, the decoloring rate can reach over 100% after 250 min.

The bionic structure nanoporous TiO2 materials were prepared using aquatic plants as biological templates. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), nitrogen adsorption method and ultraviolet-visible light spectrometer were employed to characterize the structure of samples and the degradation performance of methylene blue solution under the visible light. The results showed that TiO2 sample inherited the porous structure of original template. Such bionic material was composed of ultra-thin piece layers which were full of TiO2 nanoparticles with size of about 10 nm. The product was studded with piled pores which had a few to dozens of nanoaperture. The material was doped with a small number of bionic legacy elements which can enhance the absorption of 400-800 nm range of the visible light, thus the bionic nanoporous TiO2 materials had better photocatalytic degradation effects of methylene blue solution in the sun.

Physics-informed neural network (PINN) has been evolved into one of the most effective methods to solve the forward and inverse problems of partial differential equations (PDEs), but the limited accuracy of algorithm and the shortage of inserted inherent physical laws of PDEs are two main weaknesses of PINN. In this paper, we enforce the generalized conditional symmetry of PDEs into PINN, i.e. the generalized conditional symmetry enhanced PINN (gsPINN), to improve the accuracy of PINN. The gsPINN incorporates the inherent physical laws of PDEs and thus exerts high-efficiencies in solving the forward and inverse problems of PDEs, where the numerical experiments for the nonlinear diffusion equations with convection and source terms show that gsPINN performs better than PINN with fewer training points and simpler architecture. We discuss the computational overhead of gsPINN in terms of the relative computational cost to PINN and show that the training time of gsPINN has no obvious increases, even less than PINN for certain cases. Moreover, we perform three methods, PINN, gradient-enhanced PINN (gPINN) and the proposed gsPINN, for analyzing a non-integrable PDE and show that gsPINN has remarkable superiorities than the other two methods in terms of accuracy, robustness and training time. • The generalized conditional symmetry is the first time incorporated into PINN. • The gsPINN can give more higher accuracy numerical solution of PDEs than PINN. • The gsPINN outperforms than PINN and gradient-enhanced PINN for a non-integrable PDE. • The training time of gsPINN has no obvious increases, even less than the one of PINN. [ABSTRACT FROM AUTHOR]