Advanced Materials Research Vols. 183-185

Abstract: The α-galactosidase from rice cleaved not only α-D-galactosyl residues from the non-reducing end of substrates such as melibiose, raffinose and stachyose, but also liberated the terminal galactosyl residues attached O-6 position of the reducing-end mannosyl residue in mannobiose and mannotriose. In addition, the enzyme tore off the stubbed galactosyl residues attached inner-mannosyl residues in mannopentaose. It also could catalyze efficient degalactosylation of galactomannans, such as guar gum and locust bean gum.

Abstract: 50% (V/V) ethanol extract from laoying tea (Litsea coreana Level.) was fractionated by liquid-liquid partition using ethyl acetate, n-butanol and water, respectively. The activities of nitrite scavenging (NS) and nitrosamine formation inhibiting (NFI) of three different fractions have been investigated in vitro systems. In the above assays, all the fractions showed NS and NFI potentials to varying degrees. With regard to NS activity, fractions were effective in the order: ethyl acetate > n-butanol > water fraction. EC₅₀ values for inhibiting ability on nitrosamine formation for ethyl acetate, n-butanol and water fraction were 0.170, 0.554 and 0.725 mg/mL, respectively. Total flavonoids could be the major NS and NFI components and were in the order: ethyl acetate > n-butanol > water fraction. Based on EC₅₀ values, laoying tea especially ethyl acetate-soluble fraction may have a preventive effect against carcinogenesis induced by nitrosamines.

Abstract: Continuous dark fermentative hydrogen production technology is suitable for commercial application. This review summarized several main basic factors influencing the operation of the reactor, followed by some suggestions and outlooks. The factors included temperature, pH, HRT and COD were briefly introduced and discussed. This review demonstrated that the optimal value of a given factor under different conditions was great different. This indicates that reactor operation is affected by many factors and sensitive to environmental change. To make the technology more feasible into practice, deeply understanding about the characteristics and rules of the operation is necessary. Thus more researches in this respect are recommended.

Abstract: Thiacalix[4]arenetetrasulfonate (TCAS) was investigated as an extractant for decontaminating copper-polluted soils with elevated total copper (2000mg/kg) from the national field research station of Shenyang agroecosystems. Batch experiments were performed to test the factors influencing remediation of copper-polluted soil. The effects of solid-liquid ratio, the ionic strength and temperature on the removal capacities of copper by TCAS reagent had been studied. The results showed that the TCAS reagent was effective for removal of copper from the contaminated soil, the optimum solid-liquid ratio was 1:10 for soil treatment. Adding Ca(NO₃)₂ was of no advantage for copper removal, and the effect of Ca(NO₃)₂ on the removl rate was less when its molarity was less than 0.1mol/L. The optimum temperature of TCAS for soil treatment was 5°C-25°C.

Abstract: Constructed wetlands are widely used throughout the world to treat a wide variety of wastewater. Numerous researches on phosphorus removal have been reported, however, in practice, phosphorus removal efficiency through the constructed wetland is still relatively lower due to various reasons. In this paper, the phosphorus adsorption capacity of aerated concrete (a building material) was investigated by using Freundlich and Langmuir adsorption isotherm equations, and then the possibility, using aerated concrete waste residues for the treatment of effluent with relatively higher concentration phosphorus at the outfall of constructed wetland end through certain engineering measures, was explored. The results showed that aerated concrete not only had a higher phosphorus adsorption capacity (6.064mg/g), but also had a higher adsorption rate, compared with some other substrate materials commonly used for constructed wetlands. Coupled with the lightweight characteristic of aerated concrete, the imagination of the secondary purification pond was likely to be formed. If the imagination turns into a reality, it will not only effectively purify sewage emissions from the constructed wetland forever, but also realize the resource utilization of large quantities of aerated concrete waste residues resulting from the construction process.

Abstract: Based on an analysis of the status of urban heritage in urban ecosystem and its relationship with urban tourism development on the theory of ecological niche, this paper argues that urban heritage is a kind of nature-based human ecology, merging with natural ecology through the interaction of humans with nature, and urban heritage tourism is a kind of high-level cultural tourism, which is in essence the same with natural ecotourism while the existing problems such as non-ecological hotspots and ecological diseconomy in the urban heritage tourism are believed to take root in the narrowing and lowering of the heritage niche both in human ecology and in tourism exploitation and management. Thus the paper poses the concept of ecotype urban heritage tourism, introducing ecotourism into urban heritage tourism, and discusses the contents and requirements of ecotype urban tourism from three aspects--that is, urban space, development and management, contents and means--so as to construct a healthy urban ecosystem.

Abstract: Pesticides and heavy metals pollution in soil environment has become a serious problem in many countries including China. Two different types of soils were used in this study to assess whether high soil Cu concentrations may affect the degradation of Pys. The degradation rate of CPM and -CHT decreased with the addition of Cu to soils, indicating that Cu inhibited the degradation of CPM in soils. The results will provide more information about the potential ecological risk of chemicals on surface and groundwaters.

Abstract: It was found that there were some kinds of sulfur-oxidizing bacteria in the acidic mine water, and these bacteria could promote the dissolution behavior of heavy metals in the mining smelting waste slags. In this paper we collected a bacterium sample form a mining-water of an abandoned pyrite mine in the southwest of China and named it as FJ strain. We isolated and purified the FJ strain by 9K medium, and then made a primary identification of the purified strain. The FJ strain was gram-negative and in the shape of short rod. The strain was chemoautotrophic and aerobic bacterium, and it could oxidize the ferrous ion or the reduced sulfur as energy source to main the metabolism. The optimum growth temperature and pH is 30 °C and 2.0 separately. And we also found the strain had a considerable acid-producing ability and was eosinophilic. After a comparison and analysis, we confirmed that the physiological and biochemical characteristics of the isolated FJ strains were consistent with that of thiobacillus ferrooxidans, T ferroxidans for short. Therefore we drew a conclusion that the FJ strain we purified was just the target strains T ferrooxidans, the isolation-purification of the bacterium sample was successive.

Abstract: According to the design concept of UASB reactor with three-phase separator, a suite of self-made TUSB reactor was produced. The operational characteristics of the reactor were tested after the reactor completed start-up, and analyzed the factors that affected the COD removal rate. The results show that, as the load changes rapidly, although there was a short decline on removal efficiency; the system still can adapt to the changes quickly, and return to its original level; the load continually increases, then the removal rate tends to be constant; the same time as the volumetric loading rate increases, the gas yield is on the rise. It is proved that the reactor technology has the resistance to flow and anti-impact load capability; meantime it also shows that the high volumetric loading rate within the two-phase separation can retain the sludge, avoiding UASB sludge wastage washout under high-load operation.

Abstract: The 2-D numerical wave flume, based on the Reynolds Averaged Navier-Stokes equations and the standard turbulence model, was developed to simulate the turbulent flows with the free surface, in which the volume of fluid (VOF) method was used to handle the large deformation of the free surface and the relaxation approach of combined wave generation and absorbing was implemented, utilizing the commercial CFD software-FLUENT. The relationship of the wave parameters, initial failure velocity and the deflection angle was investigated.