Key Engineering Materials Vol. 807

Abstract: Based on the first principles and quantum mechanics, a new approach is put forward to calculate the cohesive energy of face-centered cubic solid neon, in which both the two-body and the total many-body interaction potentials are reasonably emphasized by a new combination formula. It shows that the new scheme is a simple and accurate tool to understand the high-pressure behaviors of solid neon, and it will be applied to calculate the compression curves of dense Helium, Argon, Krypton and Xenon at very high pressures. It is expected that this method can be applicable to all rare gas, including the gas, solid, and liquid phase regions, even of molecular systems, ionic systems.

Abstract: Based on the first-principles, using CCSD(T) ab initio calculation method, many-body potential energy of solid argon are accurately calculated with the atomic distance R from 2.0Å to 3.6Å at T=300K, and firstly establish and discuss the face-centered cubic (fcc) atomic crystal configurations of two-, three-, and four-body terms by geometry optimization. The results shows that the total number of (Ar)₂ clusters is 903, which belongs to 12 different geometric configurations, the total number of (Ar)₃ clusters is 861, which belongs to 25 different geometric configurations, and the total number of (Ar)₄ clusters of is 816 which belongs to 27 different geometric configurations. We find that the CCSD(T) with the aug-cc-pVQZ basis set is most accurate and practical by comprehensive consideration. The total potential energy U_n reachs saturation at R>2.0Å when the only two-and three-body interaction energy are considered. When R≤2.0Å, the total potential energy U_n must consider four-and higher-body interaction energy to achieve saturation. Many-body expansion potential of fcc solid argon is an exchange convergent series.

Abstract: Zeolite powders were first treated with hydrochloric acid, then reacted with sodium chloride, and sodium zeolite (Na-Zeolite) powders were obtained. Further Antibacterial zeolite powders were prepared by loading metal ions such as, Ag⁺ and Zn²⁺, Ag⁺ and Cu²⁺, Zn²⁺and Cu²⁺, Ag⁺ and Cu²⁺and Zn²⁺, through ion exchange. The powders were characterized by minimum Inhibitory concentration (MIC), SEM/EDXA and XRD. Antibacterial paper with antibacterial zeolite powders as filler was fabricated. The results demonstrated that MIC of loading (Ag⁺+Zn²⁺) zeolite was 125ppm against Staphylococcus aureus and Escherichia coli . MIC of loading (Ag⁺+Cu²⁺+Zn²⁺) zeolite was 62.5ppm against Candida albicans and Aspergillus Niger. By adding 6% of (Ag⁺+Zn²⁺), (Ag⁺+Cu²⁺), and (Ag⁺+Cu²⁺+Zn²⁺) antibacterial zeolite powders, respectively, antibacterial paper were prepared; and the antibacterial rate of these papers against Staphylococcus aureus, Escherichia coli, Candida albicans and Aspergillus Niger for 4h is close to 100%.

Abstract: Escherichia coli O157: H7 (E. coli O157: H7) is a foodborne pathogenic bacterium which can cause fever, diarrhoea and vomiting in humans. Thus, a rapid, simple, and specific bioprobe for pathogen detection in contaminated foods has been attracted more and more attention. In this work, the strong fluorescent amino-functionalized graphene quantum dots (af-GQDs) were prepared by hydrothermal method. The microtopographic height, surface morphology and spectroscopic properties of af-GQDs are characterized by the high resolution transmission electron microscope (HRTEM), atomic force microscope (AFM), UV-vis, fluorescence, Raman spectroscopic techniques. All the results showed that the af-GQDs can be effectively applied in the preparation of biocompatible immunofluorescence probe and in the detection of E. coli O157: H7. The minimum detection limit is 100 cfu/mL. It is a simple, rapid, sensitive, low-cost and easy to be popularized method, which provides a feasible way to monitor E. coli O157: H7 in food safety.

Abstract: Due to the developed pore structure ,high specific surface area, low cost, accessible raw materials and stable physical and chemical properties, activated carbon has caused high attention of society. Nowadays activated carbon has been widely used in capacitor electrode production, water pollution treatment, medicine and other fields. We review the various preparation methods of activated carbon and analyze the advantages and disadvantages of them in this paper. The characteristics of activated carbon regeneration technology are also discussed from the perspective of improving the utilization rate of activated carbon. With the development of China's green economy and the increasing awareness of people's environmental protection, the research on the preparation and regeneration of activated carbon will surely have a broader development prospect.

Abstract: Silver nanoparticles (AgNPs) were synthesizd by a light-assisted liquid phase reduction method with sodium hypophosphite as a reducing agent. DTAB was used to perform as the surfactant. AgNPs were characterized with powder X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the nanoparticles are spherical and cube. The effect of temperature on the morphology and properties of silver nanoparticles was investigated. The ultraviolet-visible (UV-vis) absorption and the fluorescent properties of the as-prepared AgNPs were explored.

Abstract: Graphene oxide (GO) coated fiber via deposition of GO sheets on polyvinyl alcohol (PVA) fiber containing silver nanowires (AgNWs) was fabricated, and chemical reduction for GO on the fiber surface was carried out to obtain reduced GO (rGO) coated PVA-AgNWs (rGO/PVA-AgNWs) fiber. The results showed that the rGO sheets were closely adhered on the surface of fiber, the electrical conductivity of the fiber increased with coating times of GO, and the conductivity was high up to 2.05×10^-3 S/m when GO was coated 3 times on the fiber and reduced. The synergistic effect of rGO and AgNWs for the conductivity was also clearly indicated.

Abstract: This investigation promotes the design of emulsion explosives and the development of detonation theory on a microscale. As the total composition of oxidizing and reducing elements of the reactants leave related to the thermochemistry of the system, the computational details of predicting the temperatures of detonation were introduced. It was found that a significant improvement was achieved in the emulsion explosives with an aquiferous system. An improvement in the detonation synthesis of nanolithium and zinc oxides is due to the formation of an activated matrix of the metal nitrates’ oxidizer with the corresponding fuel. Temperatures of detonation of emulsion explosives and explosive formulations are predicted using thermochemistry information. The methodology assumes that the heat of detonation of an explosive compound of composition C_aH_bN_cO_dLi_eZn_f can be approximated as the difference between the heats of formation of the detonation products and that of the explosive, divided by the formula weight of the explosive. For the calculations in which the first set of decomposition products is assumed, predicted temperatures of detonation of emulsion explosives with the product H₂O in the gas phase have a deviation of 413.66 K from results with the product H₂O in the liquid state. Fine-particle lithium and zinc oxides have been prepared by the detonation of emulsion explosives of the metal nitrates, M (NO₃) _x (M = Li, Zn) as oxidizers and paraffine as fuels, at high temperature and short reaction time. The detonation products were identified from X-ray powder diffraction (XRD) patterns, and transmission electron microscopy (TEM) measurements. XRD analysis shows that nanoparticles of lithium and zinc oxides can be produced from detonation of emulsion explosives due to fast quenching as well as appropriate detonation velocity and temperature.