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Abstract: BACKGROUND: This study aims to reveal the potential of using heterogeneous catalytic ozonation processes (HCOP) in water disinfection and provide a direction to tailor the catalytic activity by crystal facet engineering. Four kinds of MgO nanocrystals individually with exposure of (111), (200), (110) and (100) facets were prepared and used. RESULTS: It is found that MgO functions as a bactericide as well as a catalyst for ozonation. The catalytic activity of MgO nanocrystals decreases in the order MgO(111) > MgO(200) > MgO(110) > MgO(100). The apparent first‐order inactivation rate (kap) fitted by the Hom model of MgO(111)/O3 is 2.56 min‐1, which is 32.0 and 3.5 times that of single ozonation and classic MgO(100)/O3. It is confirmed by scavenger studies that •OH mainly works in MgO(111)/O3 while more direct ozonation occurs in other cases. Some O2•− are also detected in the presence of MgO. With the attack of these reactive oxidation species, cell membranes were damaged and intracellular components were released, leading to the death of Escherichia coli. CONCLUSION: These results indicate that HCOP is a promising technology for water disinfection, and crystal facet engineering is an effective strategy to enhance the catalytic performance. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJs) based on MgO barrier have been fabricated by sputtering single crystal MgO target and metal Mg target, respectively, using magnetic sputtering system Nordiko 2000. MgO barriers have been formed by a multi-step deposition and natural oxidization of Mg layer. Mg layer thickness, oxygen flow rate and oxidization time were adjusted and the tunnel magnetoresistance (TMR) ratio of optimal MTJs is over 60% at annealing temperature 385°C. The (001) MgO crystal structure was obtained when the separation distance between MgO target and substrate is less than 6 cm. The TMR ratio of most MgO based MTJs are over 100% at the separation distance of 5 cm and annealing temperature 340°C. The TMR ratios of MTJs are almost zero when the separation distance ranges from 6 to 10 cm, due to the amorphous nature of the MgO film. [ABSTRACT FROM AUTHOR]

Abstract: A formula is given which, for neutron energies in the range 10−4 < E <10eV, permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of magnesium oxide (MgO) temperature and crystal parameters. Computer program has been developed to calculate the total neutron cross-section and transmission through mono-crystalline MgO. The calculated neutron transmission and effective attenuation coefficient values for MgO-single crystal at different temperatures are compared with measured ones. An overall agreement is indicated between the formula fits and experimental data. A feasibility study for the use of MgO-single crystal is discussed in terms of the optimum MgO-single crystal thickness, mosaic spread, temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of the accompanying fast neutrons and gamma rays. Calculation shows that 10cm thick MgO-single crystal cut along its (100) plane, with 0.5° FWHM on mosaic spread and cooled at 77K, is a good thermal neutron filter, with high effect-to-noise ratio. [Copyright &y& Elsevier]

The article discusses measurement of the exo-electron currents from alternating current power distribution panel (ACPDP) test panel with or without magnesium oxide (MgO) crystals sprayed on MgO film. An inverse relationship was established between the statistical delay time and exo-electron current from the MgO cathode film. The change of the inverse curve may reportedly be due to an increased discharge success probability by the MgO crystals sprayed.

Abstract: The identification of reaction surface intermediates in the high-temperature water-gas shift reaction on iron oxide unpromoted and promoted MgO, SiO2 and TiO2 has been studied via diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The dosing of the gas mixture CO+H2O onto reduced Fe2O3/MgO as a function of reaction temperature produced formate species (1720, 1630 and 1370cm−1) as a surface intermediate. On reduced Fe2O3/TiO2 only bands characteristic of carbonate species (1630 and 1550cm−1) are observed. A direct correlation between catalytic activity and acid/base properties of our catalysts is established. The Fe2O3/MgO basic catalyst is 100 times more active than the acidic catalyst Fe2O3/SiO2. [Copyright &y& Elsevier]

Abstract: MgO nanobelts were obtained by the decomposition of magnesium nitrate in a direct current arc plasma jet chemical vapor deposition process, with a Mo substrate at 950°C for different durations. The products formed in the first 0.5min were nanobelts, some of which possessed spherical particles on tips of nanobelts, forming “tadpole-like” nanostructures. When the reaction time was extended to 1min, nanobelts become longer although spherical particles were still observed. When the reaction time was 3min, nanobelts became even longer, and no spherical particles were observed. Extending the reaction time to 5min significantly widened the nanobelts, with widths ranging from 10 to 100nm. The MgO nanobelt growth occurred along the 〈100〉 and the 〈111〉 axes. The growth mechanism of the MgO nanobelts was a combination of axial VLS and side VS growth. Nanobelts exhibited strong ultraviolet–blue photoluminescence emission under excitation at 350nm. [Copyright &y& Elsevier]