Applied Mechanics and Materials Vols. 80-81

Abstract: The pipe vibration’s mathematical model is established with help of the finite element impedance method, through the beam element simulating the pipeline structure, a finite element model of pipe system is constructed by means of CAESAR Ⅱ software, the vibration simulation and field testing is carried on in the abnormal vibration pipe joints, hangers and other parts, the simulation results and the field test results are compared, and then putting forward the damping project of the hydrogenation piping, the project is used in damping improving of the original hydrogenation piping, vibration test results indicate that the damping effect is obvious in the improved pipe joints, hangers supporting structure.

Abstract: A novel and sensitive electrochemical enzyme-linked immunosorbent assay (ELISA) system of Hydroquinones (HQ)- peroxide hydantoin (CP) -horseradish-peroxidase (HRP) by using magnetic DNA linked core-shell Fe₃O₄@ZrO₂（ZMPs）nanoparticles as labels and signal amplification was established. In the presence of carcinoembryonic antigen (CEA) analyte, the sandwich-type immunocomplex could be formed between HRP labeled CEA second antibody（CEA Ab2） modified DNA-ZMPs probes (DNA / (ZMPs-HRP-CEA Ab2) n) and nano-gold CEA modified glassy carbon electrode (GCE | CEA Ab1) as an immune electrode.The concentration of CEA was determined based on the current signal, which was generated in the reaction between HQ and CP catalyzed by HRP on the sandwich-type immunocomplex. ZMPs nanoparticles as label material can not only perform the rapid separation and purification of signal antibody on magnetic field, but also immensely enhance the labeled capacity of HRP-anti-CEA which can amplify the catalytic current signal. Furthermore, the electrode modification process was not required. The method provided a linear response range between 0.01 and 200 ng·mL^-1 with a detection limit of 4 pg·mL^-1_. Moreover, the proposed electrochemical ELISA method exhibited good precision, high sensitivity and acceptable reproducibility, and could be further developed for clinical detections of CEA and other biomarkers.

Abstract: The different age pleioblastus amarus particle were taken as the raw materials, and the wet-process bamboo powder-boards were made from the laccase-treated powder by hot pressing. The raw material chemical constituents were analyzed. The reactive oxygen species free radicals produced from the laccase-treated bamboo were detected by electron spin resonance. The physical and mechanical properties of the bamboo particleboards were measured. In order to provide some theoretical basis for producing bamboo particleboard by laccase activation, the relations between physical and mechanical properties of bamboo particle boards and chemical constituents, the reactive oxygen species free radicals were researched.

Abstract: Concrete demolition waste has been proved to be an excellent source of aggregates for new concrete production. Four types of recycled concrete specimens were made for cyclic loading tests in laboratory, in order to research the acoustics parameters and deformation feature of recycled concrete under cyclic loading. Acoustics parameters such as ultrasonic wave time, ultrasonic velocity and ultrasonic amplitude of recycled concrete were tested synchronously while recycled concrete were loaded. Test results show the evolution of fatigue total strain of recycled concrete undergoes three stages. The cycle times in the three stages accounted for 10%, 80% and 10% of the fatigue life respectively. These stages can be simulated by power function equations, first-order linear equations and exponential functions accordingly. Tests results show that wave time increased with the rise of cyclic times, while wave amplitude decreased in the same time.

Abstract: Graphite encapsulated nickel nanoparticles were prepared by ball milling andsubsequently annealing a mixture of expanded graphite with nickel powders. The products were characterized by transmission electron microscope and X-ray diffraction. The formation mechanism of the products was discussed. Results show that the products have a size range of 20-150 nm. The graphite and nickel in the products all exhibit a high crystallinity.

Abstract: In order to investigate the structural evolution of natural flake graphite with different particle sizes during the intercalation and exfoliation process, we used three natural graphites, 35, 50 and 80 mesh, as the raw material and investigated the characteristics of the three chemically prepared graphite intercalation compounds (GICs) of H₂SO₄ and the three corresponding residue GICs (RGICs). Expanded graphites (EGs) were prepared by rapidly heating the RGICs to 1000 °C in a muffle. The Results show that with decreasing the raw graphite particle size, the oxidizing reaction degree of GIC increases, but the intercalating reaction degree decreases. For RGICs, the relative ratio of RGIC phase in a sample decreases with decreasing the raw material particle size. In addition, decreasing the raw graphite particle size decreases the expanded volume of EG.

Abstract: Three graphite nanosheets were prepared by sonicating three expanded graphites that were formed by rapidly heating expandable graphite at 600, 800 and 1000 °C, respectively. The graphite nanosheets were characterized by scanning electron microscope. The anti-friction effects of the graphite nanosheets used as lubricating additives were investigated. The results show that the size of the graphite nanosheets decreases with increasing the temperature of expandable graphite. The graphite nanosheets have an obvious anti-friction effect, and the effect is related to the heating temperature.

Abstract: Expanded graphite (EG) was ball-milled in a high-energy planetary-type mill under an air atmosphere. The X-ray diffraction patterns of the products show that during the milling process (up to 100 h), the out-of-plane (L_c) and in-plane (L_a) crystallite sizes decrease gradually from 15.4 to 11.3 nm and 24.1 to 15.5 nm, respectively. The value of L_c/L_a, which is used to estimate the shape of the crystallites, increases gradually from 0.64 to 0.73. Compared with most of natural graphite, this L_c decrease degree of EG is far lower. This increased value of L_c/L_a indicates that the crystallites of the milled EG become thicker and steeper, which is contrary to the case for natural graphite.

Abstract: Two expanded graphites, EG1 and EG2 that were prepared by rapid heating expandable graphite to 600 and 1000 °C, respectively, were ball milled in a high-energy mill under an air atmosphere with 16.7% nickel addition. The X-ray diffraction patterns of the products show that that increasing the heating temperature of expandable graphite accelerates the amorphous process of the EG-Ni systems during the milling process. Ball milling the EG2-Ni mixture results in the formation of an amorphous EG-Ni system and Ni3C phase. Comparing with the amorphous process of the milled EGs without nickel addition, it is concluded that the presence of nickel restrains the process of EG1 in rate, but it promotes this process of EG2.

Abstract: A mixture of expanded graphite (EG) and nickel was ball-milled in a high-energy mill. The ball-milled EG-Ni mixtures were characterized by X-ray diffraction and their anti-friction effects used as lubricating additive were investigated. The results show that the mixtures have an obvious anti-friction effect. The effect is related with the crystallization degree of the milled EG depending on the milling time, the higher the crystallization degree, the higher the anti-friction effect.