[Fabrication of the Heterojunction Photocatalyst MoS2/BiOI and Its Investigation of Its Photocatalytic Reduction and Oxidation Activities].

Based on a two-step approach, a flower-like MoS2/BiOI composite with a heterojunction has been successfully fabricated. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared MoS2/BiOI. The formation mechanism of this heterostructure was investigated. The valence band (VB) and conduction band (CB) of the MoS2/BiOI heterojunction have been calculated based on electrochemical characterization, implying the formation of a type I band alignment. The photodegradation of Rhodamine B (RhB) and Cr6+ were used to assess photocatalytic reduction and oxidation activities. The results show that the MoS2/BiOI composite structures perform much better than pristine MoS2 and BiOI. Among the composites with various MoS2 contents, 2% MoS2/BiOI exhibits the best efficiency with respect to the degradation of RhB. After irradiation for 20 minutes, the degradation rate of RhB was 98.82%, which is 1.79 times higher than that using pure BiOI. After irradiation for 80 minutes, the removal of Cr6+ was 97.87%, which is 3.85 times higher than that using pure BiOI. Holes and·O2- are the main reactive species during the photocatalytic process of RhB degradation; holes play the leading role.

Occurrence and risk assessment of tetracycline antibiotics in soil from organic vegetable farms in a subtropical city, south China.

This study investigated the occurrence of tetracycline antibiotics in soils from different organic vegetable farms in Guangzhou, a subtropical city, South China and evaluated their ecological risk. Four tetracycline compounds (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) were extracted ultrasonically from soil samples (n = 69), with a solid-phase extraction cleanup, and were then measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results showed that four compounds were detected in all samples, with the concentrations of the individual compounds ranging from 0.04 to 184.8 µg/kg (dry weight). The concentrations of tetracycline compounds in the soils from different vegetable farms varied greatly, but their patterns of distribution were similar. Doxycycline was the predominant compound with a mean of 21.87 µg/kg, followed by chlortetracycline. The concentrations of doxycycline and chlortetracycline in 7.46 % of the samples were higher than the ecotoxic effect trigger value (100 µg/kg) set by the Steering Committee of Veterinary International Committee on Harmonization. Additionally, the concentrations of tetracyclines in greenhouse soils were significantly lower than those in open-field soils. Risk assessment based on single compound exposure showed that doxycycline could pose medium or high risks. Compared with other studies, the levels of tetracyclines in this study were relatively low. The hypothesis that antibiotic residues in the soil of organic farms fertilized with manure are higher than in the soils of conventional farms was not supported in the area studied due to the high levels of moisture, temperature, and microbial activity.

Distribution and risk assessment of quinolone antibiotics in the soils from organic vegetable farms of a subtropical city, Southern China.

Organic fertilizer or manure containing antibiotics has been widely used in organic farms, but the distribution and potential impacts of antibiotics to the local environment are not well understood. In this study, four quinolone antibiotics in soil samples (n=69) from five organic vegetable farms in a subtropical city, Southern China, were analyzed using high performance liquid chromatography-tandem mass spectrometry. Our results indicated that quinolone compounds were ubiquitous in soil samples (detection frequency>97% for all compounds), and their concentrations ranged from not detectable to 42.0 µg/kg. Among the targets, enrofloxacin (ENR) was the dominant compound, followed by ciprofloxacin (CIP) and norfloxacin (NOR). The average total concentrations of four compounds in the soils were affected by vegetable types and species cultivated, decreasing in the order of fruit>rhizome>leaf vegetables. Moreover, the average concentrations of quinolone compounds (except ENR) in open-field soils were higher than those in greenhouse soils. The concentrations of quinolone antibiotics in this study were lower than the ecotoxic effect trigger value (100 µg/kg) proposed by the Veterinary Medicine International Coordination commission. Risk assessment based on the calculated risk quotients indicated that NOR, CIP, and ENR posed mainly medium to low risks to bacteria.

[Concentrations of antibiotics in vegetables from manure-mended farm].

Sixteen typical antibiotics including four tetracyclines, four quinolones, and eight sulfonamides in vegetables from manure-amended farm were determined using the ultra high performance liquid chromatography-tandem mass spectrometry and their health risks to human via the diet pathway was assessed. Most antibiotics were frequently detected in vegetable samples, with the detection rate from 11% to 90%. Concentrations of a single compound were mainly less than 5 microg x kg(-1) (D. W.), with the maximum of 23.88 microg x kg(-1) and the average of 0.91 microg x kg(-1), respectively. Norfloxacin, ciprofloxacin, sulfamehtaoid and sulfadiazine were the dominant compounds. At least one antibiotic was detected in a single vegetable samples, and even up to ten antibiotics. The concentration of quinolones in underground parts was higher than those in aboveground parts. Intake dose of antibiotics via the consumption of the detected vegetables was lower than ADI, suggesting a lower health risk. But combination toxicity and resistance of antibiotics should not be ignored.

[Fabrication of Co3O4 nanorods and its catalytic oxidation of gaseous toluene].

Co3O4 nanorods were fabricated by the low-temperature hydrothermal method. The Co3O4 nanorods were formed through adding a small amount of surfactants (Polyvinylpyrrolidone, referred to as PVP) and reacting at 95 degrees C. Controlling the reaction time of preparation and pH of the solution can affect the properties of Co3O4 nanorods. X-ray diffraction (XRD), transmission electron microscopy (TEM) proved the as-prepared samples were Co3O4 nanorods in cubic phase. Hydrogen temperature programmed reduction (H2-TPR) and nitrogen adsorption-desorption experiment results showed that the size and pore structure of Co3O4 nanorods could be affected by different reaction time and pH, and led to the difference in specific surface area. The catalytic properties of Co3O4 nanorods were examined by degradation of gaseous toluene. The results showed that conversion of toluene was affected under low temperature by Co3O4 nanorods, which were prepared by different reaction time and pH. When the temperature was below 260 degrees C, the catalyst prepared in alkaline condition had the highest activity. However, when the temperature was higher than 260 degrees C, the conversion of toluene was hot significantly different.

Synthesis, structures and electrochemistry studies of 2Fe2S-Fe(ii)(S-2N)(2) models for H-cluster of [FeFe]-hydrogenase.

A series of model complexes [(µ-pdt)Fe(2)(CO)(5)](2)M(sip)(2) (M = Fe, Ni) were synthesized as H-cluster analogues of [FeFe]-hydrogenase. Their electrochemical behaviours were investigated and it is proposed that the bridging metal bis(tris-chelate) groups act as electron transfer sites in theses mimics.

[DNA fingerprinting structure of plankton community and its relations to environmental physical-chemical factors in Donghu Lake].

By the method of RAPD fingerprinting, this paper studied the DNA fingerprinting structure of plankton community and its relations to the main environmental physical-chemical factors at five sites in Donghu Lake. From the screened 9 random primers, a total of 210 observable bands with a length of 150-2 000 bp were amplified, 93.3% of which were polymorphic. At the five sites, the average number of amplified bands was 42, with the maximum (53) at site IV and the minimum (35) at site V. The PO4(3-)-P and TP contents were the highest at site I, NH4(+)-N, TN and NO2(-)-N contents were the highest at site V, while the values of all test physical-chemical parameters were the lowest at site IV. No obvious differences in COD, alkalinity, rigidity, and calcium content were observed among the study sites. Similarity clustering analysis showed that the DNA fingerprinting of plankton community based on RAPD marker could cluster the five sites into two groups, i. e., sites I, II and III could be clustered into one group, while sites IV and V could be clustered into another group, which was consistent with the clustering analysis based on the main environmental physical-chemical factors. In conclusion, there was a close relation between the DNA fingerprinting structure of plankton community and the main environmental physical-chemical factors in Donghu Lake.