Key Engineering Materials Vol. 904

Abstract: In the present study, nanofibers of oxidized cellulose (OC) were prepared from dried bacterial cellulose using a mixture of nitric acid/phosphoric acid and sodium nitrite. Three types of dried bacterial cellulose were used as raw materials. The results revealed that dried sheet bacterial cellulose (DSBC) yielded 86.8% oxidized cellulose with 19.4% carboxyl content, whereas squeeze-dried bacterial cellulose (SDBC) yielded 53.3% OC with 28.6% carboxyl content, and freeze-dried bacterial cellulose (FDBC) yielded 55.6% of OC with 27.6% carboxyl content. The results revealed that OC neutralized with sodium hydroxide from SDBC showed the best swelling property among all types of OC. SDBC indicated the reduction of CFU exceeds 99.99% for gram-negative bacterium Escherichia coli ATCC 25922 and gram-positive bacterium Staphylococcus aureus ATCC 6538.

Abstract: This study presents the possibility of control of nanofluidics in the bio-inspired nanosized ion channel using a field effect transistor (FET) structure. We analyzed effects from main dominant factors to control the ion flow in nanosized channel such as electro-osmosis, diffusion effect, Coulomb force between ions and pressure force. Additionally, we suggest a strategy to control the ion flow accurately at the specific position in the nanochannel by handling the viscosity, ion molecular density, pressure, gate and trans-cis voltages of FET structure.

Abstract: Gold nanoclusters (AuNCs) have gained popular attention in recent years because of their efficient tumor accumulation through EPR effect and renal clearance. In this work, we put forward a new approach to prepare glutathione-coated, ⁶⁸Ga-labeled AuNCs (⁶⁸Ga-GHS@AuNCs) with ultrasmall sizes (< 2 nm) for PET/CT imaging of tumors. GHS@AuNCs has low cytotoxicity in vitro. PET/CT imaging revealed that the ⁶⁸Ga-GHS@AuNCs could target tumor and be cleared by kidney efficiently. Our study demonstrates that ⁶⁸Ga-GHS@AuNCs has great potential for detection of tumors.

Abstract: M₂SiO₄: Tb³⁺, Mn²⁺, Nd³⁺ (M = Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺) phosphors suitable for near-ultraviolet-violet radiation excitation were successfully prepared at 1400 °C in N₂ atmosphere by a high-temperature solid-state reaction, and their phase compositions and luminescent performance were also studied by X-ray diffraction (XRD), photoluminescence spectra. Results show that their emission intensity increases in the order of Ca₂SiO₄ > Mg₂SiO₄ > Sr₂SiO₄ > Ba₂SiO₄ matrix phosphor. Ca_1.94SiO₄: 0.02Tb^{3 +}, 0.02Mn²⁺, 0.02Nd²⁺ phosphor exhibits the best luminescence performance.

Abstract: The Mo₆ cluster which has the great optical properties and chemical activity because of their unique electronic structure have been attracted attention in many fields such as phosphor and photocatalyst. However, the Mo₆ cluster it’s hard to recycling which limited its industry application because of its such small nanoscale. Immobilizing the Mo₆ cluster on 2-D material has a great value to challenge it. In this research, we study on the sulfurization process of Mo₆Br₁₂ cluster to investigate the more possibility of the immobilization of Mo₆ cluster.

Abstract: Dual-phase membrane composed of oxide ion conductor and electron conductor was fabricated for application to oxygen separation membranes. 8 mol% yttria-stabilized zirconia (8YSZ) and carbon felt were used for the oxide ion conducting phase and the electron conductiing phase, respectively. Carbon felt was impregnated with YSZ aqueous suspension (40 wt%), dried, then sintered by a spark plasma sintering (SPS) process under the applied pressure of 80 MPa at 1200, 1400 and 1600 ° C for 10 min. When sintered at 1600 ° C, the XRD pattern showed small peaks indicating the formation of the zirconium carbide phase, but the microstructure observed by SEM showed that the YSZ was well densified and tightly bonded with carbon felt. This method has been demonstrated to be an effective process for the fabrication of YSZ-Carbon composites with both phases percolation structure.

Abstract: In this paper, the YAG powder is prepared by the co-precipitation method. In addition, the sintering aid to aid sintering and the high temperature foaming agent that becomes gas released during the heating process so that the sample has pores, the ball mill mixes the material, and the sample press is extruded. Box-type resistance furnace sintering. Through this process, porous ceramics can be made. Study the effect of sintering aid content, foaming agent type, sintering temperature on the properties of YAG porous materials. The analysis and discussion can lead to the following conclusions: as the content of sintering aid silica in the sample increases, the sintering temperature of the sample decreases. It is best when the ratio of sintering aid alumina to silica is 3:1. The moldability of the sample whose foaming agent is wood chips is worse than that of the sample whose foaming agent is fiber and carbon powder. The ratio of sintering aid alumina to silica is 3:1, and the sintering temperature of the sample with carbon powder as the blowing agent is best when the sintering temperature is 1400 °C.

Abstract: A hydrothermal process was proposed to prepare BiVO₄/ diatomite composite photocatalysts, where BiVO₄ was grown from a precursor solution containing diatomite, and EDTA used as a chelating agent to prevent the precipitation of precursor solution compositions on diatomite before hydrothermal treatment. The effect of some processing parameters like diatomite percentage and Ag-loaded amount on their photocatalytic performance were also investigated in detail by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET, and UV‐Vis spectroscopy. The results show that BiVO₄/ diatomite composite photocatalysts can be successfully prepared at 160 °C for the duration of 3h by the hydrothermal process. The diatomite has two significant impacts on their photocatalytic performance: (1) enhancing the dispersion of BiVO₄ crystallites due to its high porosity and specific surface area to favor their photocatalytic performance, and (2) having a light screening effect to incident visible light to decrease their photocatalytic activity. Appropriately incorporating diatomite could improve their photocatalytic performance, but the overuse of diatomite would reduce that. Similarly, depositing Ag could effectively improve their photocatalytic activity because of its good light absorption and photosensitive characteristics, but excessive addition would result in their decrease since the overuse of Ag would also promote the electron-hole recombination.

Abstract: This study's goals are to fabricate and analyze the microstructure and optical properties of BT and Li-doped BT as the dependence of the Li concentrations (x) of 0.05, 0.1, and 0.15. The thin films of the BT and Li-doped BT have been successfully deposited on the quartz substrates by the sol-gel method. The microstructure and optical features were characterized via XRD and UV-Vis Spectrophotometer, respectively. The XRD patterns exhibit that the lattice parameter and cell volume of the Li-doped films are bigger than that of the BT due to the existence of Li doping in the BT host structure. Additionally, the tetragonality and crystallite size of all films decrease as the more Li number with the BLTO5 has the biggest lattice strain as compared to the others. Meanwhile, the optical characterization reveals that the transmittance spectra increase and the absorption edges shift to the shorter wavelengths as the addition of Li dopant indicating the bandgap values change. In contrast, the refractive index values of the films reduce by the more Li number.

Abstract: The 3 at% Al doped ZnO thin films were deposited on p-Si substrate with a native SiO₂ layer by spray pyrolysis method. Low temperature conduction behaviors were studied by analysis of impedance spectroscopy and low temperature ac conductivity. The results of impedance spectroscopy showed that the grain boundaries contributed to the resistivity of Al doped ZnO/SiO₂/p-Si heterojunction. The calculated activation energy was 0.073 eV for grain boundaries. The equivalent circuit to demonstrate the electrical properties of Al doped ZnO/SiO₂/p-Si heterojunction was a series connection of two parallel combination circuits of a resistor and a universal capacitor. Low temperature ac conductivity measurements indicated that the conductivity increased with temperature. Low temperature conductivity mechanism was electron conductivity, and the activation energy was 0.086 eV.