Advanced Materials Research Vols. 450-451

Abstract: A poly silk peptide film pH sensor has been developed using zero current potentiometry system. A poly silk peptide film coated pencil graphite electrode is connected in series between the working and counter electrodes of a potentiostat, and immersed in solution together with a reference electrode. When the solution pH varies, the resulting zero current potentiometry is linear with the values of the solution pH in the range of 1.81 to 11.58. This pH sensor shows high stability, accuracy, selectivity and reproduction.

Abstract: Cascade grinding mode is often applied to prepare Slag-Fly Ash Based cementitious materials with high volume of fly ash and slag and less cement clinker. This process has low water requirement and well fluidity, which is suitable to prepare HPC．When the W/C is 0.36, the 28d compressive strength is 58.93 Mpa, 28d flexural strength is 14.26 Mpa. By X-Ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM) analysis the results show that main materials in grinded sample are well activated by mechanical force and chemical action; more Aft are produced and observed in 3 days hydration products and the great amount of C-S-H gel has continuously generated with the growth of hydration time. By Infrared(IR) analysis, the results show that in the hydration products, the network of Silicon Oxygen Tetrahedron and Aluminum Oxygen Tetrahedra have depolymerized significantly; in the hydration process and various raw materials mutually promoted each other to accelerate the hydration reaction. The hydrates and paste structure of slag-fly ash based cementitious materials were explained．

Abstract: High-velocity impact behaviour of hybrid-fibre engineered cementitious composite (ECC) panels subjected to an impact from a hardened steel, ogive-nosed projectile at velocities between 300-700 m/s is investigated and reported in this paper. The new ECC mix contains a proportion of 0.75% volume high-modulus steel fibres and 1.25% volume low modulus polyvinyl-alcohol (PVA) fibres. The mix is designed to achieve a desired balance between the strain hardening behaviour and impact resistance of material required for impact and blast resistant structures. The new hybrid-fibre ECC demonstrates its excellent capability for impact resistance and strong potential as a protective material with reduced impact damage and distributed micro cracking.

Abstract: Spherical sponge iron (SSI) with high activity and intension possesses potential characteristics to be utilized as wastewater treatment material. Influence of reductive temperature on specific surface area and distribution of holes with different diameter were investigated. It was suggested that reductive temperature has significant influence on the specific surface area of SSI. When the temperature was controlled at T1 to T5, the porosity was 42.57% to 51.91%. When the temperature was lower than T4, the specific surface area was belonged to the range from 1.867 m2/g and 3.089 m2/g, while which declined sharply to 0.616 m2/g as the temperature increased to T5. When the reductive temperature was lower than T4, mean pore size varied from 275.7 nm to 449.6 nm, while which increased abruptly to 1270 nm as temperature increased T5. To utilize the SSI in wastewater treatment to remove pollutants, T4 was the optimized temperature.

Abstract: Three bacterial strains were isolated from oil contaminated soil samples in Yumen oilfield of China and selected due to their capacity of growing under extreme conditions and production of bioemulsifier. The isolates were identified as Brevibacillus sp. XS1, Geobacillus sp. XS2 and Geobacillus sp. XS3 according to 16S rDNA sequence and physiological methods, respectively. The isolates XS1, XS2 and XS3 were thermotolerant with the optimum growth temperature of 50 °C, 60 °C and 55 °C, respectively. All the three isolates were able to produce bioemulsifiers which had little effect on surface tension reduction. The bioemusifiers produced by the three isolates were purified with a production yield of 2.98g/L, 4.24g/L and 3.82 g/L, respectively. The bioemulsifiers were identified as anionic heteropolysaccharides by FTIR analysis and their average molecular weight and polydispersity were investigated by GPC method. The bioemulsifiers produced by Geobacillus sp. XS2 and XS3 exhibited a perfect stability over various temperature (up to 100 °C), pH (range from 2.0 to 12.0) and salinity (up to 30.0% of NaCl concentration) and were considered to be ideal candidates in MEOR process.

Abstract: In recent years， as the load increasing gradually，problems in voltage stability of regional power network which is the terminal of power grid is serious. From the voltage stability machine rational analysis to roll out small interfering voltage stability criterion of new, and the modal method is used to determine the key nodes and areas of the system theory basis.

Abstract: Soybean concentration proteins were extracted from defatted soybean meals with ethanol agent method. Crude soybean oligosaccharides were gained after recovery the alcohol by concentration with the soybean whey water as row material. Then a series of purification process such as precipitating proteins, desalting with ion exchange and decolorizing carbon were used to obtain soybean oligosaccharides end product. The soybean oligosaccharides refining process technique and parameters were presented in this paper and could be applied to large-scale industrial production. Physical chemical quality index of soybean oligosaccharides after refining was that concentration was 70%, total sugar purity was no less than 85%, protein content was 1.3% (dry base content), ash content was 0.73% (dry base content).

Abstract: Failure process of laminated composites is performed by progressive failure analysis method. A modified form of Hashin’s failure criterion by Shokrieh is used to investigate the failure, where a sudden degradation model is proposed to reduce engineering material constants. The numerical study of laminated composites is implemented in ANSYS Parametric Design Language (APDL). The initiation and propagation of local damage and response of laminated composite structures from initial loading and ultimate failure are predicted. The model has been validated by comparing numerical results with existing experimental results. And then failure analysis of specimen fabricated from M40J/Ag80 on influence of the hole has been performed by the proposed model.

Abstract: Advancement in the study of carbon nanotube has enabled its application in civil engineering as constitutive materials or additives. In this study, the availability of applying multi-walled carbon nanotube to improve the characteristics of cement composites was investigated with experiments on more than 30 specimens. The multi-walled carbon nanotubes (MWCNTs) were effectively dispersed in the water with surfactant, which can keep stable for over 3 months. Specimens with MWCNTs of 0.025%, 0.05% and 0.1% of cement (by weight) were tested with a loading machine and then analyzed with a SEM. It was found that the compressive strength of the samples increased with the increasing MWCNTs, it can improve the 7-day compressive strength by 22% . Microscopic analysis (SEM) revealed that carbon nanotubes were surrounded with hydration products. The bridging and debonding of carbon nanotubes in cement pastes was observed as well.

Abstract: Using metallographic test, physicochemical phase analysis, X-ray diffraction and transmission electron microscope, the microstructure of seismic rebars with yield strength of 500MPa, which were fabricated by vanadium and nitrogen microalloying and controlled rolling and controlled cooling, were investigated. The results of metallographic test show that the microstructure in centre and interlayer of tested rebar samples are made up of ferrite, pearlite and a small amount of bainite, but tempered sorbite with thickness of 0.9mm on the edge of the rebars. Physicochemical phase analysis indicates that vanadium in the rebars had precipitated by VN mainly, and the precipitation rates of V and N are 60% and 70%, respectively. The result of strengthening mechanisms analysis shows that fine grain strengthening and transformation strengthening are the dominated contributions to strength and strengthening increments of them are 184.4 MPa and 111.6 MPa, respectively.