Modulating the oxygen evolution reaction activity of SrIrO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 catalysts using electric-field polarization.

The physical properties of epitaxially grown SrIrO3 thin films are sensitive to external influences. This provides a rare opportunity to study their physical properties as regulated by electric-field polarization of their substrates, thus affecting their oxygen evolution reaction activity. In this work, SrIrO3 films were epitaxially grown on (001)-oriented Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMNPT) single-crystal substrates by pulsed laser deposition. After applying an electric field to the PMNPT along the [001] direction, a lattice strain is induced by rotation of its ferroelectric domains, and this lattice strain is transferred to the interior of the SrIrO3 film through the epitaxial interface. This changes the surface resistivity of the SrIrO3 film and affects its electrocatalytic activity. Our findings suggest that substrate polarization is a feasible method for regulating the electrocatalytic performance of SrIrO3 thin films, and this provides new inspiration for the structural design of other composite catalysts.

Vacancy cluster in ZnO films grown by pulsed laser deposition.

Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-related defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-related defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed.

Enhanced giant magnetoimpedance in heterogeneous nanobrush.

A highly sensitive and large working range giant magnetoimpedance (GMI) effect is found in the novel nanostructure: nanobrush. The nanostructure is composed of a soft magnetic nanofilm and a nanowire array, respectively fabricated by RF magnetron sputtering and electrochemical deposition. The optimal GMI ratio of nanobrush is promoted to more than 250%, higher than the pure FeNi film and some sandwich structures at low frequency. The design of this structure is based on the vortex distribution of magnetic moments in thin film, and it can be induced by the exchange coupling effect between the interfaces of nanobrush.

[Folic acid prevents Bcl-2 hypomethylation in rats with hyperhomocysteinemia].

OBJECTIVE: To investigate the effects of folic acid on Bcl-2 gene methylation status in rats with hyperhomocystinemia induced by ingestion of excess methionine. METHODS: 36 healthy 6-week-old wistar male rats, weighing (160 +/- 10) g, after being fed adaptable for one week, were randomly divided into control group (n = 12), hyperhomocysteinemia group (n = 12), folic acid treatment group (n = 12). The control group was fed with AIN-93G diet. The hyperhomocysteinemia group was fed with high-methionion diet, consisting of AIN-93G diet plus 1.7% methionion. The folic acid treatment group was fed with high-methionion plus folic acid-rich diet, consisting of AIN-93G diet plus 1.7% methionion and 0.008% folic acid. After be maintained for 18 weeks on the previously described diets, the concentrations in the plasma Hcy and folic acid and Vit B12 were measured with the IMX assays. The thoracic aorta was harvested for immunohist Chemical analysis. The methylation status of Bcl-2 gene was determined by nest touch-down PCR combined MSP(methylation specific PCR). Real-time RT PCR was used to detect mRNA expression of arotic Bcl-2. RESULTS: The study showed the following: (a) A high methionine diet for 18 weeks is sufficient to induce hyperhom degree Cystinemia; Folic acid supplementation to the rats fed the high-methionine diet prevented an elevation homocysteine (Hcy) levels in the plasma (P < 0.01 ). (b) Compared with the control group, the Hhcy group had a elevating Bcl-2 expression by immunohistochemical analysis in aorta, along with Bcl-2 hypomethylation (P < 0.05) and increased Bcl-2 mRNA expression (P < 0.05 ). (c) Most important, after folic acid supplementation, the lowering of Hcy levels was accompanied by a marked decreased Bcl-2 expression by immunohistochemical analysis and Bcl-2 hypermethylation (P < 0.05) and reduced Bcl-2 mRNA expression (P < 0.05). CONCLUSIONS: Folic acid supplementation can prevents Bcl-2 hypomethylation in rats with hyperhomocysteinemia, resulting in a decreased Bcl-2 expression.

Nanoscale characterization and magnetic reversal mechanism investigation of electrospun NiFe2O4 multi-particle-chain nanofibres.

NiFe(2)O(4) multi-particle-chain nanofibres have been successfully fabricated using electrospinning followed by calcination, and their morphology, chemistry and crystal structure were characterized at the nanoscale. Individual NiFe(2)O(4) nanofibres were found to consist of many nanocrystallites stacked along the nanofibre axis. Chemical analysis shows that the atomic ratio of Ni : Fe is 1 : 2, indicating that the composition was NiFe(2)O(4). The crystal structure of individual NiFe(2)O(4) multi-particle-chain nanofibres proved to be polycrystalline with a face centered cubic (fcc) structure. The nanocrystallites in the nanofibres were revealed to have a single-crystal structure with random crystallographic orientations. The magnetic measurements reveal that the NiFe(2)O(4) multi-particle-chain nanofibres have a coercivity force of 166 Oe. A "chain of sheets" micromagentism model was proposed to interpret the observed magnetic behaviour of the NiFe(2)O(4) multi-particle-chain nanofibres. Simulation studies of the coercivity are in good agreement with the experimental results at room temperature. It is believed that this work will significantly expand the use and application of these compounds in the field of biomagnetic nano-devices and improve understanding of the magnetic origin of spinel ferrites.

Synthesis and luminescent properties of a novel bluish-white afterglow phosphor, b-Zn3(PO4)2:Hf4+.

A new bluish-white long-lasting phosphorescent material, Hf4+-doped b-Zn3(PO4)2, was prepared by the conventional high-temperature solid-state method. The photoluminescence (PL) spectrum reveals that it exhibits a strong blue emission band centred at 470 nm, with asymmetry on the long wavelength side; this material emits bluish-white light and shows strong afterglow phosphorescence after it is excited with a 254 nm UV lamp. The phosphorescence lasts nearly 40 min in the light perception of the dark-adapted human eye (0.32 mcd/m(2)). The possible phosphorescence mechanism is also analysed.