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1

Combined Influence of Silicon Content and Oxygen Concentration on the Oxidation Process of Silicon-Containing Steels

Yuan Q., Xu G., Zhou M., He B., Hu H.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

445--450

EN

The combined influence of silicon content and oxygen concentration on silicon-containing steels was investigated, via a heating route similar to that applied in the industrial reheating process, using a Simultaneous Thermal Analyzer (STA). Four different oxygen concentrations and three different isothermal holding times were designed. The results show that the effect of silicon on the mass gain depends on the oxygen concentration and the oxidation time. The mass gain of low-silicon steel is greater than that of high-silicon steel at 1260°C in the oxygen concentrations of 1.0 vol.% and 2.0 vol.%, even when the isothermal holding time is 90 minutes. However, there is a critical time point for mass gain in oxygen concentrations ≥3.0 vol.%. The mass gain of lowsilicon steel is greater before and smaller after this critical point. The critical time is deferred with decreasing oxygen concentration.

2

Palaeo-earthquake events during the late Early Palaeozoic in the central Tarim Basin (NW China): evidence from deep drilling cores

He B., Qiao X., Jiao C., Xu Z., Cai Z., Guo X., Zhang Y.

Geologos

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2014

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Vol. 20, No. 2

105--123

EN

Various millimetre-, centimetre- and metre-scale soft-sediment deformation structures (SSDS) have been identified in the Upper Ordovician and Lower-Middle Silurian from deep drilling cores in the Tarim Basin (NW China). These structures include liquefied-sand veins, liquefaction-induced breccias, boudinage-like structures, load and diapir- or flame-like structures, dish and mixed-layer structures, hydroplastic convolutions and seismic unconformities. The deformed layers are intercalated by undeformed layers of varying thicknesses that are petrologically and sedimentologically similar to the deformed layers. The SSDS developed in a shelf environment during the early Late Ordovician and formed initially under shear tensile stress conditions, as indicated by boudinage-like structures; during the latest Ordovician, SSDS formed under a compressional regime. The SSDS in the Lower-Middle Silurian consist mainly of mixed layers and sand veins; they formed in shoreline and tidal-flat settings with liquefaction features indicating an origin under a compressional stress regime. By Silurian times, the centre of tectonic activity had shifted to the south-eastern part of the basin. The SSDS occur at different depths in wells that are close to the syn-sedimentary Tazhong 1 Fault (TZ1F) and associated reversed-thrust secondary faults. Based on their characteristics, the inferred formation mechanism and the spatial association with faults, the SSDS are interpreted as seismites. The Tazhong 1 fault was a seismogenic fault during the later Ordovician, whereas the reversed-direction secondary faults became active in the Early-Middle Silurian. Multiple palaeo-earthquake records reflect pulses and cyclicity, which supports secondary tectonic activity within the main tectonic movement. The range of SSDS structures reflects different developments of tectonic activity with time for the various tectonic units of the centralbasin. The effects of the strong palaeo-earthquake activity coincide with uplift, fault activity and syn-tectonic sedimentation in the study area during the Late Ordovician to Middle Silurian.

3

The study on pH gradient control in solution for driving bacteria

He B., Wang Z., Xu C., Shen R., Hu S.

Biocybernetics and Biomedical Engineering

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2013

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Vol. 33, no. 2

88--95

EN

Medical applications are the most impactful areas of microrobotics, such as targeting tumoral lesions for therapeutic purposes, minimally invasive surgery (MIS) and highly localized drug delivery. However, miniaturization of the power source with an effective on board controllable propulsion system has prevented the implementation of such mobile robots. Flagellated chemotactic bacteria can be used as an effective integrated propulsion system for microrobots. In this paper, we study the pH gradients control in solution for driving bacteria. The swimming property of flagellar bacteria and mechanism of forming the pH gradient field in solution are discussed. By experiments, we found that the pH gradient field distribution in solution is mainly related to the electrode shape. And the input voltage value can control the stable time of the pH gradient field, while it has no effect on the distribution of the field. The electric potential distribution is analyzed by simulation with COMSOL Multiphysics. The simulation results are consistent with the experiment results, which indicate that the bacteria movement can be controlled by the electrodes' shape and the input voltage.

4

Dielectric properties of Y-doped Ba1-xSrxTiO3 ceramics

Xu J., Liu H. X., He B., Hao H., Li Y. Q., Cao M. H., Yu Z. Y.

Optica Applicata

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2010

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Vol. 40, nr 1

255--264

EN

Y-doped Ba1-xSrxTiO3 (Y-BST) ceramics (x = 0.1, 0.2, 0.4, 0.7) were prepared by solid-state reaction and sintered at 1250, 1300, 1350, and 1400 °C for 1 h. The effect of strontium solution and sintering temperature on the structure, microstructure and dielectric properties of Y-BST was investigated. SEM investigations revealed a grain size decreasing with the Sr content increase. The temperature dependence of permittivity showed decrease in phase transition temperature with higher Sr content. Enhancing sintering temperature is effective to increase the grain size and improve the microstructure porosity. The XRD patterns of all Y-doped Ba0.3Sr0.7TiO3ceramics indicated that the crystal cell parameters increase when temperature increased. However, the (002) and (200) peaks of Y-doped Ba0.3Sr0.7TiO3 split when sintering temperature was increased to 1400 °C, which makes the structure of the specimen transit to tetragonal (a = 3.9857 A and c = 4.018 A) from cubic. It may be attributed to the fact that Y3+ ion can occupy both A site and B site of Ba0.3Sr0.7TiO3 sintered at 1400 °C, which leads to the large different internal stress in individual grains, and then induces the structure change. The temperature coefficient of capacitance (TCC) value of the Y-doped Ba0.3Sr0.7TiO3 sintered at 1400 °C changed little within š6% over a temperature range from 10 to130 °C.