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Plasma electrolytic oxidation (PEO) is a surface-treatment process extensively used to protect the surfaces of light metals such as Mg, Al, and Ti. Here, we report an environmentally friendly PEO process that uses nitrogen-containing electrolytes and low voltages (120 V) to form ~ 12 micron thick, uniform, adherent and porous oxide coatings on T1 titanium alloy surfaces. We evaluated the influence of nitrogenation by comparing the coatings to alloys treated in PEO baths without nitrogen-containing compounds. Both sets of samples exhibited basalt-like morphologies with distinct variation in the pore structures. The composition analyses showed that the coatings were primarily composites of titanium oxides and silicates. The T1 Ti alloys treated with nitrogen-containing electrolytes also contained TiC and TiN. This is the first ever report of producing TixOy, Ti–Si–O, TiC, and TiN composite coatings using a single PEO bath without carbide/nitride nanoparticles. The bandgaps of the coatings suggested visible light functionality. The use of nitrogen-based compounds in the PEO baths improved the hardness of the oxide layers but introduced stress-induced cracking which are potentially responsible for the reduction in corrosion resistance of the nitride and carbide containing coatings. [ABSTRACT FROM AUTHOR]

Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance. [ABSTRACT FROM AUTHOR]

Black nickel coatings are widely used in industries due to their shiny black color and other unique properties. However these coatings are normally soft, which limits their applications. In order to increase the mechanical properties of black nickel coatings, sol-enhanced technology has been applied to the plating process. TiO2 sol-enhanced black nickel nanocomposite coatings were electroplated on nickel-coated brass. A systematic study on the microstructure and properties of the black coatings were conducted. The effects of TiO2 concentration (TiO2 sol concentration in 0-20 mL/L) on the surface morphology, nanohardness and wear resistance have been studied. The results indicated that the nanohardness of the sol-enhanced black nickel coating was increased by 20%. The mechanisms of improvement and surface morphology variation were also discussed. [ABSTRACT FROM AUTHOR]

Abstract: ZrO2 nanoparticles was uniformly co-deposited into a nickel matrix by electroplating of nickel from a Watts bath containing particles in suspension which were monodispersed with dispersant under DC electrodeposition condition. It was found that morphology, orientation and hardness of the nanocomposite coatings with monodispersed ZrO2 nanoparticles had lots of difference from the nanocomposite coatings with agglomerated ZrO2 nanoparticles and pure nickel coatings. Especially, the result of hardness showed that only a very low volume percent (less than 1wt.%) of monodispered ZrO2 nanoparticles in Ni–ZrO2 nanocomposite coatings would result in higher hardness of the coatings. The hardness of Ni–ZrO2 nanocomposite coatings with monodispersed and agglomerated ZrO2 nanoparticles were 529 and 393HV, respectively. The hardness value of the former composite coatings was over 1.3 times higher than that of the later. All these composite coatings were two–three times higher than that of pure nickel plating (207HV) prepared under the same condition. The strengthening mechanisms of the Ni–ZrO2 nanocomposite coatings based on a combination of grain refinement strengthening from nickel matrix grain refining and dispersion strengthening from dispersion state of ZrO2 nanoparticles in the coatings. [Copyright &y& Elsevier]

Macrophages are key responders of inflammation and are closely related with oxidative stress. Activated macrophages can enhance oxygen depletion, which causes an overproduction of reactive oxygen species (ROS) and leads to further excessive inflammatory response and tissue damage. Agmatine, an endogenous metabolite of L-arginine, has recently been shown to have neuroprotective effects based on its antioxidant properties. However, the antioxidant effects of agmatine in peripheral tissues and cells, especially macrophages, remain unclear. In this study we explored the role of agmatine in mediating antioxidant effects in RAW 264.7 cells and studied its antioxidant mechanism. Our data demonstrate that agmatine is an activator of Nrf2 signaling that markedly enhances Nrf2 nuclear translocation, increases nuclear Nrf2 protein level, up-regulates the expression of the Nrf2 downstream effector HO-1, and attenuates ROS generation induced by Lipopolysaccharide (LPS). We further demonstrated that the agmatine-induced activation of Nrf2 is likely through the PI3K/Akt pathway. LY294002, a specific PI3K/Akt inhibitor, abolished agmatine-induced HO-1 up-regulation and ROS suppression significantly. Inhibiting HO-1 pathway significantly attenuated the antioxidant effect of agmatine which the products of HO-1 enzymatic activity contributed to. Furthermore, the common membrane receptors of agmatine were evaluated, revealing that α2-adrenoceptor, I1-imidazoline receptor or I2-imidazoline receptor are not required by the antioxidant properties of agmatine. Taken together, our findings revealed that agmatine has antioxidant activity against LPS-induced ROS accumulation in RAW 264.7 cells involving HO-1 expression induced by Nrf2 via PI3K/Akt pathway activation. [ABSTRACT FROM AUTHOR]

In this paper, laser interference induced dielectrophoresis (LIIDEP) was presented for cell manipulation and three-dimensional array assembly. Two-beam and three-beam interference systems were built to manipulate yeast cells in deionized water. When the laser power was 60 μW and the sinusoidal AC signal was 6 V at 10 kHz, the two-beam interference pattern manipulated the cells into a single-row array distribution. For three-beam interference, when the laser power was 70 μW and the frequency was 4.5 kHz, the voltage of 2.5 V enabled each spot to control one cell, and 7.5 V enabled many spots to control multiple cells. When the cell concentration was 2 × 107 cells/mL and the electrical signal was 8 V and 4.5 kHz, the cells were assembled into a three-dimensional columnar array. The feature size of laser interference pattern was adjusted to microscale and maintained sharp boundaries, which effectively improved the manipulation accuracy. Compared to the projector or laser as the ODEP light source, LIIDEP has the advantages of high manipulation resolution, good contrast and large dielectrophoretic force. This work provides an effective way for high resolution three-dimensional array manipulation and assembly of a large number of living cells on the microscale in liquid environments. • The interference pattern effectively improves the precision of cells operation. • Two-beam interference pattern manipulated cells into a single-row array distribution. • Each spot of the three-beam interference pattern controls single or multiple cells. • The cells can be quickly assembled into a 3D columnar array. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor-binding protein 7 (IGFBP7) has been identified as a secreted protein associated with a number of cellular processes. However, the specific regulatory mechanisms of IGFBP7 on podocytes of diabetic nephropathy (DN) are yet to be elucidated. In the present study, podocytes were identified initially via an immunofluorescence assay using an anti-synaptopodin antibody. It was subsequently demonstrated that glucose promoted podocyte proliferation in a time- and dose-dependent manner via MTT assay. In addition, IGFBP7 expression was silenced in podocytes via siRNA, the effects of which were evaluated using western blotting and reverse transcription-quantitative polymerase chain reaction. It was demonstrated that silencing IGFBP7 inhibited apoptosis and epithelial mesenchymal transformation (EMT) of podocytes mediated by high glucose (HG). Transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog (Smad) signaling was associated with proliferation, apoptotic activities and EMT. Therefore, the expression levels of TGF-β1/Smad pathway were detected, and it was observed that silencing IGFBP7 suppressed the TGF-β1/Smad pathway in podocytes induced by HG. These findings suggested that IGFBP7 may serve as a potential therapeutic target for DN. [ABSTRACT FROM AUTHOR]

Gold (Au) coatings are widely used for electrical contacts in devices, decoration and jewelry. However, the relatively low hardness and poor wear resistance of pure Au coatings lead to a short service life and limit their application. Ni is frequently used as an alloying element to enhance the hardness but it lowers the conductivity of Au coatings. In this research, Co was co-deposited as an alloying element with Au to improve its mechanical properties while maintaining conductivity. TiO2 sol in different concentrations was added to the Au-Co plating bath to further enhance the coating strength. Systematic studies including surface morphology, hardness, wear resistance and electrical conductivity have been carried out. Key results from nanoindentation tests demonstrated that the hardness of Au-Co-TiO2 composite coating was increased by 30% when compared to a pure Au-Co coating, while the electrical conductivity has been kept at the same level. [ABSTRACT FROM AUTHOR]

Sn coatings were widely used in electronic and device industries due to their unique properties. Sn-TiO2 sol-enhanced nanocomposite coatings were prepared in order to improve the mechanical properties of Sn coatings. The microstructure, mechanical properties and conductivity of sol-enhanced Sn-TiO2 nanocomposite coatings were systematically investigated. The results show that after adding an optimum quantity of TiO2 nanoparticles, the nanohardness of Sn-TiO2 coatings was increased by 75% while the conductivity remained unaltered when compared with a pure Sn coating. The effect of TiO2 sol addition on the properties of coatings was discussed. [ABSTRACT FROM AUTHOR]

Ni-Co-ZrO2 nanocomposite coatings have been electroplated on mild steel by adding ZrO2 nanoparticles into an Ni-Co plating solution. The microstructure and mechanical properties of nanocomposite coatings were systematically investigated. The results show that the microhardness of Ni-Co-ZrO2 nanocomposite coatings varied significantly with the quantity of ZrO2 nanoparticles. Ni-Co-10 g/L ZrO2 nanocomposite coating exhibited the optimum mechanical properties due to the dispersion strengthening effect. Addition of ZrO2 nanoparticles beyond 10 g/L led to particle agglomeration and caused a porous coating structure, resulting in a deterioration of coating mechanical properties. [ABSTRACT FROM AUTHOR]