Advanced Materials Research Vols. 535-537

Abstract: The specimens were machined from DD6 single crystal superalloy blades with low angle boundary. The misorientation of LAB was measured with EBSD technique in scanning electron microscope. The microstructures of specimens with LAB were examined in optical microscope and scanning electron microscope. The formation mechanism of low angle boundary of DD6 single crystal superalloy blades was investigated. The results showed that he formation of LAB which is caused by the deviating orientation from ideal [001] and the angle between the crystal orientation and shell is crystal selection process acted by dendrite competitive growth rule. Part of dendrites have changed their growth orientation a little to the decreasing [001] orientation departure angle because of solidification condition fluctuating during dendrites branching process. The LAB is the obvious interface between the deforming dendrites and their surrounding dendrites.

Abstract: Split Hopkinson pressure bar setup was used as experimental method for dynamic impacted testing at 573K at the strain rate of 7030s-1. The microstructure of Al-5.8Cu aluminum alloy impacted plate was characterized by transmission electron microscopy (TEM). The findings indicated that dislocation network of Al matrix was observed, which was attributed to isothermal and adiabatic process during impaction. The researched results indicated the dislocation network of Al matrix was inhabited by coarsened precipitate in Al-5.8Cu alloy impacted plate.

Abstract: By using a low frequency inverted torsion pendulum, the high temperature internal friction spectra of Al-0.02wt%Zr and Al-0.1wt%Zr alloys were investigated respectively. In Al-0.02wt%Zr alloy, the conventional grain boundary internal friction peak (Pg) is observed with some small unstable peaks. In Al-0.1wt%Zr alloy, the bamboo peak is observed to appear at the high temperature side of the conventional grain boundary internal friction peak. The conventional grain boundary internal friction peak decreased and moved to higher temperature. The bamboo peak owns an activation energy of 1.75eV. When average grain size exceeded the diameter of samples, Pb strength was reduced and its position was shifted to a lower temperature. Based on the grain boundary sliding model, Pg and Pb peaks were explained. Their dependence on annealing temperature and time was determined by considering the effects of contained Ce atoms and other impurities on the relaxation across grain boundary.

Abstract: Some samples of La2/3(Ca(1-x)Znx)1/3MnO3 （x = 0, 0.2, 0.4, 0.6, 0.8, 1.0） were prepared by solid-state reaction method at 1623K. The crystal structures of the compounds were studied by X-Ray Diffraction(XRD). All the samples are orthorhombic structure (Pnma), the symmetry has no obvious change with the increase of Zn atom content x. The crystal lattice constants, Mn-O bond length and Mn-O-Mn bond angle varied with the different Zn content, analyzed by the Rietveld method.

Abstract: The Dabie orogen of east-central China marks the boundary between the North China and Yangtze Cratons, and is characterized by juxtaposition of the ~400Ma Tongbai metamorphic belt and the ~220Ma South Qinling-Dabie metamorphic belt. The Triassic collision between the North China and Yangtze Cratons which generated numerous granitoid intrusions such as the Shangcheng, Xingxian and Lingshan intrusions, and other small stocks, such as Tangjiaping, Dayinjian, Mushan and so on. Those shallow-emplaced granite porphyries are closely related to porphyry-skarn Mo and Mo-W deposites, forming the Dabie molybdenum metallogenic belt. Molybdenum deposits occur in the endo- and exocontact zones of the porphyry, include with three major types of Mo mineral systems, i.e., porphyry, less porphyry-skarn and vein-type. The ore-forming ages of the molybdenum deposits in Dabie area are mainly cluster 127.8±0.9~113.1±7.9Ma. The pulse is the product of the transformation of the tectonic regime from NS- to nearly EW-directions in East China.

Abstract: This article presents the results of the synthesis of carbon nanomaterials: Nanoscale materials obtained by carbonization of waste agricultural products (apricot kernel, walnut, rice husk). The results of physico-chemical characteristics of the obtained nanomaterials.

Abstract: The methods of culture-dependent and denaturing gradient gel electrophoresis (DGGE) based on the sequence of 16S rRNA V3 region gene were described to comparatively characterize the microbial population and community structure of cutlassfish (Trichiurus haumela) under the cold storage. The results showed that 13 kinds of bacteria were identified by the traditional culture-dependent methods, the dominant bacteria belonged to Shewanella putrefaciens and Pseudomonas fluorescens. To determine the community profiles of the samples on variable V3 region, the bacteria of 16S rRNA gene were amplified by PCR and 11 distinct PCR products were separated by DGGE fingerprinting technology. From the sequence analysis, Psychrobacter sp. was found to be the predominant bacteria in the initial stage of the storage. The proportion of Shewanella sp., Pseudomonas sp. increased gradually with the extension of storage time, and they took the place of Psychrobacter sp. to be the dominant bacteria. Thereinto, both Pseudomonas fluorescens and Vibrio sp. took high proportions in the process of storage due to the deterioration of cutlassfish (Trichiurus haumela).

Abstract: The purpose of this study was to evaluate the effect of modified atmosphere packaging (MAP) with varying O₂ concentrations on the quality changes of Pacific white shrimp during cold storage at (4±1)°C by using the quality indices such as Total viable counts (TVC), TVB-N, pH, firmness, whiteness and sensory evaluation. Results showed that MAP inhibited the microbial growth and the spoilage which was confirmed by the lowered TVC and TVB-N. Among the four MAP groups, shrimp packaged in bags 40%CO₂\55%O₂\5%N₂ showed the lowest level of TVC and TVB-N, and shrimp in 40%CO₂\5%O₂\55%N₂ had the best appearance with lighter blackspots during storage. Low O₂ concentration packaging exhibited the ability to retard melanosis, but weakening the ability to impede the spoilage. Extremely high O₂ concentration with low CO₂ concentration packaging inhibit the microbial growth compared to the CK, but improved the melonasis of shrimp and reduced its sensory quality rapidly.

Abstract: High water absorption material was prepared by graft copolymerization of calcium lignin sulphonate with acrylic acid and acrylamide. Effect of process parameters on graft copolymerization and sample properties was investigated by means of the single-factor method, and the microstructure of fracture surface of the water absorbent resin was analyzed by SEM. The result shows that: when mass percents of acrylic, acrylamide, calcium lignin sulphonate, initiator and crosslinking agent are 65.5%, 19.5%, 15%, 0.09%, and 0.05%, respectively, and neutralization degree is 60% with 2h of initiation reaction time and 1.5h of crosslinking reaction time. The water absorption rate of material is up to 1010g/g, and 0.9wt% NaCl solution absorption rate is up to 110g/g.

Abstract: The Wiesenberger number is a common dimensionless quantity to reflect the elastic effect of fluids. It’s usually applied in mechanical calculation of viscoelastic fluid and calculated by the first normal stress difference. So the first normal stress difference and Wiesenberger number are applied to describe the viscoelasticity of polymer solutions. Though many literature reviews on the viscoelasticity of polymer solutions have been reported, only a few studied the Wiesenberger number and the first normal stress difference of viscoelastic fluid. Since the corresponding relation between Wiesenberger number and mass concentration and salinity of polymer solution is not clear, HAAKE RS150 rheometer was used during all steady and dynamic shear experiments, effects of mass concentration and salinity on the visco-elasticity of polymer solution in low shear rate were discussed, first normal-stress difference and Wiesenberger number were calculated. Results show that: with the increase of mass concentration of polymer solution and the decrease of salinity, both first normal-stress difference and Wiesenberger number increase, the visco-elasticity of polymer solution increases; At the same shear rate, the higher the salinity is, the smaller the first normal stress difference is, the smaller the Wiesenberger number is and the less obvious the viscoelasticity is. The Wiesenberger number of ordinary polymer solution used in the oilfield is about 1 when the shear rate is 10s-1and salinity is 508mg/L.