Advanced Materials Research Vols. 726-731

Abstract: Batch experiments of OECD Guide were conducted to the adsorption and desorption of tetracycline in soils. The adsorption and desorption isotherms of tetracycline in cinnamon soil and red soil were expressed well by the Freundlich equation at 20, 25 and 35°C. According to lg K_f and 1/n values of fitting parameters, tetracycline was strongly adsorbed by two soils with adsorption capacity (lg K_f) values from 3.06 to 3.59. Temperature from 20 to 30°C had little effects on the tetracycline adsorption in two soils. Thermodynamic parameters depict the exothermic nature of adsorption, and the process was favorable and spontaneous. Hysteresis effect was observed. The maximum adsorption capacity and hysteresis index of tetracycline were found at 20°C for cinnamon soil and 30°C for red soil, so there was little risk of tetracycline remobilization with temperature lower than 25°C in cinnamon soil or higher than 25°C in red soil.

Abstract: This study assesses enantioselectivity on the degradation of tebuconazole in wheat grain, straw, and soil in Beijing and Zhejiang under open field conditions. After agricultural application, the analytes were extracted from soil and grain with acetonitrile, and from straw with acetonitrile containing 1% acetic acid through ultrasonic extraction. The extracts were cleaned by dispersive-solid phase extraction, and determined by chiral liquid chromatography-tandem mass spectrometry with a Lux amylose-2 column. The results of field trials indicated that the degradation of tebuconazole enantiomers followed first-order kinetics in straw and soil at the two sites. Their half-lives in straw ranged from 3.88 to 4.93 days, which were shorter than those in soil ranging from 40.76 to 43.86 days. The (-)-tebuconazole showed faster degradation in straw from Beijing and Zhejiang. In Zhejiang soil, preferential degradation of (+)-tebuconazole was observed, whereas (-)-tebuconazole was preferential in Beijing soil. The terminal residues of (-)-tebuconazole in most grains were higher than those of its antipode, indicating significant enantioselective residues.

Abstract: In order to observe the attraction effects of the artificial reef models on Alepocephalus, the behavior and distribution of Alepocephalus in the experimental flume under the presence of five reef models with different shapes and structures were studied using experimental ethology method, and the attraction effects of different reef models were compared. The results indicate that the distribution of Alepocephalus is rather dispersed when no reef model is put into the marked area of the flume, and they prefer to stay in relatively dark area. In this case, the Alepocephalus distribution ratio of the reef marked area is 7%. When reef models are put into the marked area, Alepocephalus shows obvious positive taxis to them. And the Alepocephalus distribution ratio of the reef marked area increased to a level between 16 % and 29 %. In addition, the apertured cubical reef model shows the best attraction effect with a distribution ratio of 29 %.

Abstract: Oxygen supply is the primary factor in ensuring human survival in confined spaces. Compared with high pressure oxygen bottles, potassium superoxide oxygen board has advantages such as small size, large oxygen storage per unit volume, absorbing carbon dioxide while providing oxygen. However, the release rate of chemical oxygen in a confined space relates to the concentration of carbon dioxide, temperature, humidity and other environmental parameters. To meet human survival needs within the refuge chamber, this paper made experiments on potassium superoxide oxygen production performance factors, including humidity test, carbon dioxide concentrations test, surface spray wet test and so on. Through tests the amount and the rate of oxygen production, and the removal efficiency of carbon dioxide of potassium superoxide in different situations are obtained. And through a human survival experiment, the potassium superoxide oxygen board can satisfy the human body needs is validated. These all provide basis for the establishment of auxiliary oxygen supply facility in the refuge chamber.

Abstract: γ-polyglutamic acid (PGA) was firstly used for recovery and immobilization of Pseudomonas delafieldii R-8 cells in biodesulfurization process. The PGA mediated flocculation was combined with celite adsorption to immobilize R-8 cells and the as-prepared immobilized cells showed a high initial specific desulfurization rate at 0.243 mmol l^-1 h^-1 and a good desulfurization stability with 95% desulfurization activity remained after 6 batches of desulfurization processes.

Abstract: A bacterial strain NAPZ, which utilized polycyclic aromatic hydrocarbons (PAHs) as the sole carbon and energy source for growth, was studied on its apparent characteristics, key gene structure and functions. It was preliminarily identified as a Bacillus sp. according to its physiological characteristics and the phylogenetic property of its 16S rRNA gene sequence. Based on the reported RHD gene sequences, a pair of primers was designed to amplify the RHD gene from the genomic DNA of strain NAPZ by PCR. Then, the RHD gene was cloned and sequenced. Based on this sequence and its related sequences in the GenBank database, a multiple alignment was conducted then a phylogenetic tree was constructed with DNAMAN and MEGA software. The analysis revealed that strain NAPZ oxidized PAHs via ring hydroxylating dioxygenase (RHD) pathway. The study provided experimental and theoretical support for revealing the structure and function of key genes as well as the PAHs-degrading pathways in strain NAPZ.

Abstract: Erigeron breviscapus (Vant.) Hand-Mazz is the raw materials to product Health drugs and injectable formulations. Study the genetic diversity of Erigeron breviscapus under harmful substances stress provides insight into their genetic variation characteristics under stress. In this research, genetic diversity of Erigeron breviscapus under heavy metals (Cr, Cd, Hg, Cu, Pb) stress with different concentrations were analyzed by using 8 inter-simple sequence repeat markers (ISSR). The results showed that Erigeron breviscapus had rich genetic variation under five different kinds heavy metals stress. A total of 96 bands were amplified, of which 80 polymorphic bands were discovered and the percentage of polymorphic bands (PPB) was 83.33%. Their indexes of Na, Ne, H, I and PPB were calculated. Richer genetic diversity was discovered under Cu stress, followed by Cd, Cr, Pb and Hg stress in order. This study will be provide a scientific basis to improve the quality Erigeron breviscapus and optimize its growing conditions.

Abstract: In this study, columns packed of a greenhouse soil with various soil fertile levels (low, medium and high) were carried out under greenhouse condition. The leaching experiment lasted 51 days. There were four fertilization treatments including no fertilizer [CK], chemical fertilizer [NPK], organic manure [M], organic manure and chemical fertilizer [M+NPK]. Microbial biomass C and N were measured. The results were as follows: organic or inorganic fertilizer increased the contents of soil microbial biomass C and N, and combination of chemical fertilizer and organic fertilizer significantly elevated the amount of soil microbial biomass C and N compared to organic or inorganic fertilizer treatment. There were significant differences in the amount of microbial biomass C and N among different fertile level soil under different fertilization practices in 0-20 and 20-40cm soil layers. Our study showed that application of manure and chemical fertilizer at proper rates according to soil fertile status is beneficial to increase the amount of microbial biomass C and N.

Abstract: In this paper, two kinds of different pollution degree soils denoted as L1 and L2 were used as test soils. Desorption experiment was carried out to study the impacts of pH and electrolyte on desorption characteristics of cadmium (Cd) in soils. The results showed that the variation trends of Cd desorption rates with increase in pH were similar. In other words, it decreased as pH increased. In acidic region, desorption rate of heavy metal Cd decreased rapidly as pH increased. When pH = 4, Cd desorption rate was largest; in neutral and alkaline regions (pH = 7-10), desorption rate of heavy metal Cd decreased slowly as pH increases. Cd desorption behavior was closely related to type and concentration of electrolyte. Under the same concentration, Cd desorption capabilities of three electrolytes in soils L1 and L2 could be expressed in following order: CaCl₂> Ca (NO₃)₂> NaCl.

Abstract: In order to study the effect of chlorine (Cl₂) inactivating Cryptosporidium and Giardia in water, different factors as Cl₂ concentration, contact time, pH, temperature, turbidity and organic content which might influence the inactivation were studied by using fluorescence staining method. With the Cryptosporidium and Giardia was 1×10⁶ cysts/mL, turbidity 1.0NTU, temperature 22°C, pH 7.0, and after 280 min reaction, under the condition that the Cl₂ concentrations was 8.0mg/L, the inactivation ratio could be more than 99%. With increases in turbidity, the inactivating effect decreased. If the inactivating time achieved 360 min, it could meet the presetting inactivation ratio with turbidity 0.1~10.0 NTU. The inactivating capability of Cl₂ was found to be stronger under acidic than that under alkalic conditions. Inactivation rate improves with a temperature increase from 5 to 25°C, but decreases beyond this.