The spontaneous oxidation of crystallized ZrAu at room temperature leads to the formation
of ultrafine monoclinic zirconia (MZ) particles (about 3.6 nm in diameter). The presence of
tetragonal phase (TZ), generally observed in very small zirconia particles, was investigated
by X-ray diffraction and Raman experiments but was not observed. Thermodynamical
calculations considering the finite size effects in zirconia were introduced to explain the
formation of pure MZ considering experimental and theoretical surface energies. The results
of these calculations associated with the near equilibrium conditions used for synthesis
demonstrate that the monoclinic structure is the stable crystallographic structure of zirconia
nanocrystals at room temperature.
In this study we first report the elaboration of gold and zirconia clusters (ranging from 3.5 to 7 nm in size) obtained by air oxidation of crystallized ZrAu at 25 °C within a few hours. This transformation was observed using X-ray diffraction, infrared spectroscopy (transmission and DRIFTS), and electron microscopy (SEM and HREM) techniques. This solid-state nanostructuration is interpreted as a consequence of combined mechanisms: adsorption and diffusion of oxygen, segregation of gold atoms from ZrAu alloy onto Au clusters, and acceleration of the process by internal residual stress and percolation of the electronic current via gold-cluster chains. The gaseous species adsorption by very small gold clusters supported by zirconia formed at the initial step of this oxidation could induce "catalytically assisted nanostructuring oxidation". Large amounts of gold and zirconia nanoparticles are obtained at the end of this process.
Abstract. Bamboo charcoal was produced by pyrolysis or carbonization process with extraordinary properties such as high conductivity, large surface area and adsorption property. These properties can be improved by activation process that can be done thermally or chemically. In this paper, carbonization and activation process of bamboo, its structural and adsorption properties will be presented. Herein, the adsorption properties of bamboo charcoal that has fully utilized in solar cell as the electrode, adsorbent for water purification and electromagnetic wave absorber are reviewed.
A virtual private network (VPN) connects a private network to the internet, primarily the public network, through a secure tunnel. Using a local area network (LAN) segment, users can send and receive data from their colleagues in different locations on the network. The development of VPN allows users to gain access to company applications and databases. Therefore, data can be transmitted through a secure tunnel without the need to configure port forwarding for the internet of things (IoT) gateway, allowing users to access it from any location in the world. A method such as dataplicity and pitunnel was examined to compare with the conventional setting. This research paper examines the current deployment of VPN connections in IoT gateways, discussing their characteristics, benefits, and drawbacks, as well as comparing them. The advantage of this method is that the IoT gateway is always accessible and has internet connectivity, w
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