Applied Mechanics and Materials Vols. 687-691

Abstract: Alkali metal (Cs/Li/Na) adsorption on (5, 5) and (9, 0) single-walled carbon nanotubes (CNTs) with a capped edge had been investigated by first-principles calculations. Our calculations are performed within density functional theory (DFT) under the generalized gradient approximation (GGA) of Perdew, Burke, and Ernzerhof (PBE).For the indefective (5, 5)/(9, 0) CNT, adsorption energy ordering of the alkali-metal adatoms is Cs>Li>Na so that the Cs adsorption was energetically favored with respect to the Li/Na adatom. However, the adsorption energy ordering of the alkali-metal adatoms for the defective (5, 5) CNT was Li>Cs>Na. Therefore, separation selectivity for alkali metals could be actualized using the capped single-walled carbon nanotubes. The (5, 5)/(9, 0) P-CNT adsorbed Cs atoms preferentially, while the (5, 5)/(9, 0) defective CNT (D-CNT) adsorbed Li atoms advantageously.

Abstract: In this paper, we have employed first-principles calculations to investigate the adsorption mechanisms of one lithium atom on the sidewalls of 1/2/3 H-adsorbed indefective/defective (3, 3) single-wall carbon nanotubes (CNTs) which have vacancy defects. Our calculations are performed within density functional theory (DFT) under the generalized gradient approximation (GGA) of Perdew, Burke, and Ernzerhof (PBE).Our results show that the lithium atoms strongly binds to the H-adsorbed (3, 3) nanotube. Lithium atoms can chemically adsorb on (3, 3) nanotube with the vacancy defect (MVD) without any energy barrier. The lithium adsorption will enhance the electrical conductivity of the nanotube. Further more, the structure of the (3, 3) nanotube with the MVD and hydrogen atoms will become more stable after the three kinds of lithium adsorption.

Abstract: In this paper, we have employed density functional theory (DFT) to investigate the adsorption mechanisms of atomic hydrogens on the sidewalls of (3, 3) single-wall carbon nanotubes (CNTs) which have vacancy defects. All the calculations were performed using the generalized gradient approximation (GGA) with the Perdew, Burke and Ernzerhof (PBE) correlation functional.Our results show that hydrogen atoms can chemically adsorb on the defective nanotube. Bonding energy of per hydrogen atom decreases with the number of adsorbed hydrogen atoms. The hydrogen atoms will enhance the electrical conductivity of the (3, 3) nanotube. Besides one hydrogen atom adsorbing on the nanotube with a vacancy defect (MVD), hydrogen atoms move towards the MVD of the nanotube.

Abstract: Using the methyl trimethoxy silane (MTMS) and methyl triethoxy siliance (MTES) each modified the surface of nanosilica sol.Through measuring the percent conversion of silance coupling agent and the water absorption of the cement paste.the optimal technical processes of the modified silica sol were obtained:: M_{coupling agent} = 3:1,pH = 2,the synthesis temperature of 40 °C,the Synthetic time for 40 min. MTMS hydrophobic effect of modified silica sol significantly better than MTES, the higher the stability of the solution and the infrared spectrum analysis of the grafting mechanism of silane coupling agent.

Abstract: CrSiN coatings of different silicon content were deposited on 1Cr18Ni9Ti austenitic stainless by d.c. reactive magnetron sputtering in a closed field unbalanced system. Comparative studies on microstructure and mechanical properties between CrN and CrSiN coatings with various Si contents were carried out. The structure of the CrSiN coatings was found to change from crystalline to amorphous structure as the Si contents increased. Amorphous phase of Si₃N₄ compound was suggested to exist in the CrSiN coatings. The crystalline grain became smaller in CrSiN coatings. With the increasing Si content, the coating deposition rate slew down, while the hardness of coatings improved obviously and the best hardness was about 4200 HV_0.01 when the Si content was 1.13%.

Abstract: Li_0.97K_0.03FePO₄ and Li_0.97K_0.03FePO₄/graphene composites were synthesized by carbothermal reduction method using acetylene black as carbon source. The structure and electrochemical properties of the prepared materials were investigated with X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, galvanostatic charge and discharge and electrochemical impedance spectra tests. The results indicated that K doping improves the cyclic stability of samples, the addition of small amounts of graphene results in better electronic properties on sample. Li_0.97K_0.03FePO₄/graphene showed discharge capacity of 158.06 and 90.55 mAh g^-1 at 0.1 C and 10 C, respectively. After the 50 cycle test at different rates, the reversible discharge capacity at 0.1 C was 158.58 mAh g^-1, indicating the capacity retention ratio of 100.32%.

Abstract: nanoMn₃O₄ was prepared by a simple solvothermal method. The structure, morphology and electrochemical properties of the products were investigated by XRD, SEM and constant current discharge-charge test. The results of XRD and SEM shows that nanoMn₃O₄ is high-purity, and it’s diameter is about 30 nm. It could deliver an initial discharge capacity of 1324.4 mAh g^-1 at the current density of 25.5 mA g^-1, and the specific discharge capacity is 586.9 mAh g^-1 after 30 cycles at the current density of 30.4 mA g^-1.

Abstract: We report on the preparation and hydrogen desorption/absorption kinetics of nanocrystalline magnesium hydride (MgH₂) added commercial Ti by high-energy ball milling. The phase and composition of the as-milled powders are characterized by X-ray diffraction (XRD). The results show that the milled sample contained MgH₂ phase, Ti phase and small amount of MgO phase. When the milling time is 30 h, the hydrogen desorption property of MgH₂ has been investigated and found that the sample releases 0.43, 0.86 and 0.90 wt% H₂ in 200 minutes at 280, 290 and 300 ^oC , respectively. Moreover, the sample absorbs 0.48, 0.0.58 and 0.61 wt% H₂ in 15 minutes at 280, 290 and 300 ^oC , respectively. It can be seen that the kinetics of hydrogen desorption/absorption of MgH₂-Ti composite has been greatly enhanced compared to the pure MgH₂.

Abstract: Fe²⁺ is widely used as a coagulant to enhance the primary SBR sewage treatment process. Based on SBR system, this paper studies the change trend of phosphate content in various stages by simulating the interaction between sewage and the precipitates produced with Fe²⁺ in the sediment as a coagulant. The results indicate that excluding the impact of activated sludge, the concentration of PO₄³⁺ increases in the end of the anaerobic stage with the increase of FePO₄ cumulant in the sediment and there is an equimultiple relationship between the increase of the concentration of PO₄³⁺ in the effluent and the FePO₄ dosage and that the accumulation of Fe (OH)₃ can contribute to the subsequent sustainable phosphorus removal, but the cumulant increase of Fe (OH)₃ has no significant influence on the effects of phosphorus removal.

Abstract: Magnesium sulfate monohydrate is described as a dual element quality fertilizer. The preparation and application prospect of magnesium sulfate monohydrate was introduced in this paper, and the use of magnesium-rich brine resources in the preparation of magnesium sulfate monohydrate was prospected.