Abstract: Newly developed boriding process, which was performed by heating the metal using high-frequency induction furnace then melt the salt consisted of borax, carborundum and silicon carbide, was applied to several kinds of steels in order to find its feature. The study was carried out on the effect of chemical composition in steels and salts on the properties of the boride layer. Thick layer was obtained by using the salt containing carborundum. Increasing chromium content of the steels inhibited boriding and consequently needle-like boride layer changed into smooth one. Induction heating process offer thicker boride layer than the conventional immersion method.
Abstract: High-temperature brazing molybdenum using palladium and titanium foils have been investigated in the experiment. Successful brazed joints are achieved from using the palladium filler foil. Brazed joints are fully dense and free of any intermetallic phase. Three point bending strengths of 246 and 233 MPa are obtained from joints using 100 m thick palladium filler foil brazed at 1580 and 1610 oC for 600 s, respectively. The application of palladium filler foil shows potential in brazing molybdenum for high-temperature application.
Abstract: A hybrid surface treatment was performed to improve the surface properties and the durability improvement of turbo shaft material Inconel718. A micron sized (µ) WC-metal powder (86% WC 10% Co 4% Cr) was coated onto a substrate surface using HVOF thermal spraying, and the coating was heat treated by a CO2 laser. With the HVOF coating of the powder onto the substrate, the surface hardness of substrate increased approximately 300% from 399 Hv to 1260±30 Hv, and further increase of approximately 40% from1260±30 Hv to 1820±100 Hv by laser heating the coating for 0.6 s. Porosity of coating decreased more than five times from 2.2±0.3% to 0.4±0.1% by laser heating. According to the reciprocating sliding test, friction and wear behavior of coating improved by coating for both sliding surface temperature of 25°C and 450°C. Therefore, the HVOF coating and laser heat treatment of coating are recommended for the durability improvement of turbo shaft materials.
Abstract: The cis-1,4-polybutadiene rubber(BR)/organic montmorillonite(OMMT) /attpulgite(AT) nanocomposites were prepared by using solution method. The results of TEM showed that the OMMT and AT layers were dispersed in BR matrix on nano-scale. Compared with the pure BR, the tensile strength of BR/OMMT/AT nanocomposites increased by 600% when added 6% OMMT/AT. The results showed that the conversion of butadiene polymerization was higher than 90% by using recycled solvent. The nanocomposites had excellent thermal stability. The dynamic mechanical analysis showed that Tg of BR/OMMT/AT nanocomposites shifted to higher temperature, and the nanocomposites had a good rolling resistance. The composites displayed better dynamic mechanical properties.
Abstract: An enzymatic method for γ-aminobutyric acid (GABA) production was invested. With this method, rice bran was used as glutamate decarboxylase (GAD) source and exogenous monosodium glutamate(MSG) was used as substrate. We stimulated the rice bran GAD via regulating the temperature, pH, reaction time, buffer and adding PLP, Ca2+ and substrate. In the existence of PLP and Ca2+, the GABA content of rice bran had been improved by about 45 fold. The GABA production reached 2.3g/100g bran, and the Glu conversion reached 100%. As rice bran is a by-product in rice processing and a large quantity of rice bran is commercially available, our study illuminated a safe and efficient way to produce GABA and GABA enriched food.
Abstract: Three Vibrio parahaemolyticus isolates 17802(tdh﹣, trh﹢, tlh﹢), 33846(tdh﹢, trh﹣, tlh﹢) and 05432 (tdh﹣, trh﹣, tlh﹢) were exposed to chloramine-T and sodium hypochlorite to investigate their susceptibility and resistance to chlorine-containing disinfectants. Results showed that sublethal disinfectant condition contributed to the formation of resistant strains, which minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were 2 folds higher than original strains. Differences were observed in physiological and biochemical properties between the original and resistant strains including growth kinetics, cultural character and biochemical characterizations, the resistant strains demonstrated higher lag phase than the original strains in the growth of tryptic soy broth (TSB) with adding 2.5% NaCl. They lost the abilities to grow in thiosulfate citrate bile sucrose（TCBS）media and chromogenic (CHROM) agar and to produce certain proteases such as lysine decarboxylase, ornithine decarboxylase and urease. The most significant change in biochemical characters of the strains was that the resistant strains could grow in the media without containing salts while the original strains could not.
Abstract: This study is aimed to evaluate the tensile strength of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-cementitious ratio, dosage of silica fume, steel fiber length and dosage. Test results indicate that the compressive strength and direct tensile strength of specimens for fiber length of 25 mm are higher than that of 50 mm. The strength properties increase with increasing fiber content. Incorporation of fiber and silica fume in composites achieves significantly higher increase in compressive strength and direct tensile strength than only use of fiber or silica fume. In addition, the compressive strength, splitting tensile strength, direct tensile strength and impact resistance are fairly correlated. It contributes that the fiber content influences crack arresting ability and the silica fume influences interfacial bonding effectively.
Abstract: For the treatment of contaminated rainwater runoff, the synthesis of manganese dioxide and its coating onto buoyant polypropylene granule was done with accompanying adsorption experiments. Results showed 35-45 m oxide coating was stable under severe hydrodynamic conditions, had 37 mg of Mn attached per gram of granules, moreover, consisted of mixed birnessite and cryptomelane forms of manganese dioxide. Adsorption capacity of each gram of media was 4.9, 3.9, 0.98, 0.75 mg of Pb , Cu , Cd , and Zn , fitting well to the Freundlich adsorption model. Manganese-dioxide-coated polypropylene granules had favorable engineering advantages and excellent adsorptive properties, being challenging alternative to other practically-oriented in situ or centralized rainwater treatment media.
Abstract: The studying used different metakaolin replacement ratio of cement mortar exposed to different environments to investigate the quality of cement with metakaolin basic mechanical properties of materials and white efflorescence quantify the effect of microscopic properties. The specimens were analyzed with Compressive strength test and Matlab image analysis. The results presented that: (1) Comparing with between the appropriate amount of metakaolin replacement of cement and control group, the compressive strength of the appropriate amount of metakaolin replacement of cement is higher than control group’s. Especially, the compressive strength of 15% metakaolin replacement of cement is the highest; (2) Matlab image analysis the amount found in white efflorescence into freezers > carbon tube ≒ normal atmosphere.
Abstract: In the present study, the problem of functionally graded materials (FGMs) under a stress pulse is analyzed based on smoothed particle hydrodynamics (SPH) using the formulation for large deformation. First, the formulation of SPH for this problem is described, and a benchmark calculation is performed and compared to one-dimensional analytical solutions. The behavior of FGMs subjected to a stress pulse is then investigated for several cases, including various distributions of inhomogeneous materials and two-dimensional problems with different boundary conditions. It is found that in the two-dimensional case, if there is a free boundary not parallel to the direction of the external force, the influence from this boundary cannot be ignored.