Advanced Materials Research Vols. 726-731

Abstract: Salt lake environments are economically and ecologically important issues. Like any other ecosystems in the world, salt lake ecosystems are facing various kinds of pollutions. However, little information is available on the biodegradation of organic pollutants by halophilic microorganisms in such environments. In the present work we isolated a strain of phenol-degradating bacteria from a salt lake in Inner Mongolia. Sequence of 16S rRNA suggested that the strain belong to Propionibacterium genus. The strain can grow with phenol as a sole carbon source under 10% (w/v) salt concentration. PCR amplifications with the primers for multicomponent phenol hydroxylase or catechol 1, 2 dioxygenase gene were applied to genome DNA of the strain, suggesting that phenol might be transformed to catechol by multicomponent phenol hydroxylase and further degradated through ortho-ring cleavage pathway. When the primers for catechol 1, 2 dioxygenase were applied to the DNA obtained from the lake water, at least two types of catechol 1, 2 dioxygenase genes sequences were obtained, suggesting the presence of the bacteria with diverse aromatic compound-degradating genes.

Abstract: Fungus has been valued as one of edible and medicinal resources, and bioactive substances have been identified in many fungus species. In all of them, polysaccharides are the most famous and potent fungus-derived substances with antioxidant, antitumor, immunoregulation and so on. Although the isolation process and bioactive activity of fungal mycelium polysaccharides have been investigated in the past decade, the new bioactive activity and the mechanism of fungal mycelium polysaccharides are not systematic studied. These studies are still in progress and the role of polysaccharides as bioactive activity is especially under intense debate. The purpose of the present review is to summarize the available information of isolation process and bioactive activity, and to reflect the current status of these research areas with a view for future direction.

Abstract: For reducing ammonium concentration and guaranteeing safe drinking water, three heterotrophic bacteria were isolated from the Songhua River, which were SFA6, SFA7 and SFA11. When the initial ammonium concentration was about 130 mg/L, the ammonium removal rate of the strains SFA7, SFA6 and SFA 11 were 1.54 mg NH₄⁺/L/h, 1.20 mg NH₄⁺/L/h and 1.27 mg NH₄⁺/L/h respectively at 8 °C. The 16S rDNA sequence results revealed that the strain SFA6 was Bacillus subtilis, SFA7 was Pseudomonas putida, and SFA11 showed similarity to Pseudomonas nitroreducens. The biochemical characteristics of SFA6 were quite different from that of SFA7 and SFA11. After 48 h degradation, the NH₄⁺-N (about 5 mg/L) was consumed to 0.23±0.15 mg/L, 0.37±0.20 mg/Land 0.58±0.17 mg/L by the strains SFA6, SFA7 and SFA11, with little NO₃^--N and NO₂^--N accumulation. Above all, the strains SFA6, SFA7 and SFA11 could be used in drinking water treatment at 8 °C. The strain SFA6 showed the highest ammonium removal efficiency.

Abstract: The litter accumulation and decomposing biomass characteristics under meadow, typical steppe and desert steppe were comparatively studied. Results showed that accumulation and decomposition of litter was the biggest under meadow than typical steppe and desert steppe. Variance analysis indicated that accumulation mass and decomposition rate among the three steppe types were significantly different. Therefore, litters accumulation of different steppe types was greatly affected by precipitation and temperature.

Abstract: To investigate the headspace volatiles in shrimp head P. borealis, optimized conditions were evaluated for solid-phase microextraction coupled to gas chromatography-mass spectrometry method. SPME fibers of 100-μm polydimetylsiloxane, 65-μm polydimetylsiloxane-divinylbenzene, 75-μm carboxen-polydimetylsiloxane, and 50/30-μm divinylbenzene-carboxen-polydimetylsiloxane (DVB/CAR/PDMS) were compared. The influence of several parameters such as type of fibers, volume of sample, extraction time, extraction temperature, and state of samples was systematically investigated. Suitable reproducibility and sensitivity were achieved by combining DVB/CAR/PDMS of 50/30-μm thickness as the liquid phase of SPME, 1.5 g of shrimp head lyophilized powder, 40 ^OC of isolation temperature and 40 min of isolation time. A total of 62 volatile compounds have been confirm, including hydrocarbons, ketones, alcohols, aldehydes, esters, nitrogen-containing compounds and sulfur-containing compounds. 3,5-octadien-2-one (E,Z), 3,5-octadien-2-one (E,E), 1-penten-3-one, 6-octen-2-one, ethyl acetate and alcohols such as 1-penten-3-ol, 2-penten-1-ol and 1-octen-3-ol were predicted as key compounds for SH flavor.

Abstract: NiFe₂O₄ prepared by a coprecipitation method was reduced by NH₃ to form appropriate amounts of oxygen deficiency, and then the resulting ferrite samples were subjected to the CO₂ flow at 80°C under UV light irradiation. The experimental results showed that the decomposition of carbon dioxide did not take place in dark, but CO₂ could convert to carbon under photo-assistance at 80°C. TEM results suggested that CO₂ decomposed to various forms of carbon, including carbon nanotubes, carbon microspheres, etc. Further, ferrites reduction time is a very important factor for influence the conversion of CO₂.

Abstract: Physiological response abilities of Leymus chinensis with different leaf colors were determinated under drought stress. Soluble sugar content, activity of APX of L. chinensis in five leaf colors all increased along drought stress gradients while MDA content decreased along drought stress gradients. Regression model analysis showed that the relationships between soluble sugar content, MDA content, activity of APX of L. chinensis in five leaf colors and drought stress concentration were significant y=a+bx linear function. Soluble sugar content, the activity of APX increased along leaf color gradients, but MDA content decreased along leaf color gradients. Regression model analysis suggested that the activity of APX, soluble sugar and MDA content and chlorophyll a, chlorophyll b and total chlorophyll contents were significant positive y=ae^bx or y=ax^b functions. Therefore, the results suggested that: drought-tolerant ability of L. chinensis was strongly enhanced with the increase of leaf color. There was significant divergent adaptability to drought among different leaf colors L. chinensis.

Abstract: Anatase TiO₂ nanosheets with different percentage of exposed high-reactive {001} facets were synthesized successfully. Besides the FESEM and TEM anslysis, XRD, Raman, and PL analysis were also conducted systematically to give a new insight on analyzing the as-prepared {001} facets dominated TiO₂ photocatalysts. Photocatalytic activities of the photocatalysts were tested by the degradation of methylene blue (MB) aqueous solution under UV irradiation. The results indicated that there was an optimal percentage of the exposed {001} facets existed to give the highest photocatalytic activity of as-prepared TiO₂ nanosheets. A possible mechanism for the enhanced photocatalytic activity of the {001} facets dominated anatase TiO₂ was also proposed.

Abstract: A type of cross-linking starch microspheres (CSMs) has been synthesized by reversed phase suspension method using soluble starch as raw material. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The static adsorption behaviors of Co²⁺ on the cross-linked starch microspheresand were investigated. The CSMs and its adsorption product were comparatively characterized by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption behaviour of CSMs in different temperatures is in agreement with the Freundlich isothermal equation and isothermal equation of Langmiur. The thermodynamic parameters of adsorption process indicate that entropy is the main adsorption driving force, and physical adsorption is main about the adsorption behaviors of CSMs on Co²⁺.These data are helpful for the adsorption separation of metal ions and the treatment of the wastewater containing Co²⁺. Keywords: cross-linked starch microspheres;cobalt ions;adsorption mechanism;thermodynamics adsorption

Abstract: Based on quantitative structureproperty relationship (QSPR) of organic compounds, geometrical optimization and quantum chemical parameter calculations have been performed at the B3LYP/6-31G* level of theory for 75 polychlorinated naphthalenes (PCNs). A number of statistically-based parameters have been obtained. Relationship between the physicochemical properties of polychlorinated naphthalene compounds (n-octanol/air partition coefficient, sub-cooled liquid vapor pressure, water solubility) and the structural descriptors have been established by multiple linear regression (MLR) method. The results show that the molecular volume (V_mc), dipolar moment (μ), and the energy of lowest unoccupied molecular orbital (E_LUMO), together with the quantity derived from electrostatic potential () can be well used to express the quantitative structure-property relationships of polychlorinated naphthalene compounds. The models constructed have good robustness and high predictive capability.