Sensitive detection of H2S based on Ce doped ZnCo2O4 hollow microspheres at low working temperature.

In order to develop a highly efficient H2S gas sensor at low working temperature, in this work, a kind of novel Ce-doped ZnCo2O4 hollow microspheres (Ce/ZnCo2O4 HMSs) were successfully synthesized using a template-free one-pot method, showing a sensitive response toward H2S. The microstructure and morphology of the material were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The gas-sensing performance of the composite was investigated, showing that the ZnCo2O4 doped with 6 mol% Ce had the highest response to 20 ppm H2S at a low operating temperature of 160 °C with a response value of 67.42, which was about 2 times higher than that of original ZnCo2O4. The prepared Ce/ZnCo2O4 HMS sensor in response to H2S exhibited a linear range of 0.1-200 ppm with a low detection limit of 0.1 ppm under the conditions of ambient humidity of 45% and ambient temperature of 20 °C. Meanwhile, it also possessed good selectivity, repeatability and reproducibility. The response value of the sensor decreased by 5.32% after 7 months of continuous monitoring of H2S in an atmospheric environment of a pig farm, indicating that the sensor had a long-term stability and continuous service life with important application prospects.

An Au/SnO-SnO2 nanosheet based composite used for rapid detection of hydrogen sulphide.

In this work, a new type of H2S sensor was fabricated by means of drop-coating of an Au/SnO-SnO2 nanosheet material, which was prepared by a one-pot hydrothermal reaction, onto a gold electrode in an alumina ceramic tube with the formation of a thin nanocomposite film. The microstructure and morphology of the nanosheet composites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A gas-sensitivity study presented good H2S-sensing performance of such Au/SnO-SnO2 nanosheet composites. At an optimal operating temperature of 240 °C and ambient temperature of 25 °C, the resulting sensor showed a good linear response to H2S in a range of 1.0 to 100 ppm with a low detection limit of 0.7 ppm, and a very fast response-recovery time of 22 s for response and 63 s for recovery, respectively. The sensor was also unaffected by ambient humidity and had good reproducibility and selectivity. When being applied to the monitoring of H2S in an atmospheric environment in a pig farm, the response signal to H2S was only attenuated by 4.69% within 90 days, proving that the sensor had a long and stable service lifetime for continuous running and showing its important practical application prospects.

The complete chloroplast genome of Scoparia dulcis (Plantaginaceae).

Here, we report the complete chloroplast genome of Scoparia dulcis L. The genome is 153,701 bp in size. Two inverted repeats (IRs) with a total of 50,546 bp were identified. The rest of the sequence was separated into two single-copy regions, including a large single-copy (LSC) region (85,029 bp) and a small single-copy (SSC) region (18,126 bp), respectively. The genome of S. dulcis comprised of 129 genes, including 85 protein-coding genes, 8 rRNA genes, and 36 tRNA genes. Phylogenetic analysis showed that S. dulcis was strongly allied with Bacopa monnieri.

In vitro Induction and Generation of Tetraploid Plants of Sophora tonkinensis Gapnep.

BACKGROUND: Sophora tonkinensis Gapnep. is an important medical plant in China. Early researches of S. tonkinensis were focused on rapid propagation and quality analysis of in vitro tissue culture plantlet, and still no research focuses on the plant breeding of and there were no excellent varieties for artificial cultivation of S. tonkinensis. OBJECTIVE: To set up a method to generate and select the best varieties of S. tonkinensis by polyploid breeding after induction by colchicine treatment. MATERIALS AND METHODS: The adventitious buds were submerged in different concentrations of aqueous colchicine solution for different lengths of time to induce polyploidy in the plants, and the induced buds were identified by root-tip chromosome determination and leaf characteristics comparison. The contents of matrine and oxymatrine of radix ex rhizoma in 13 selected tetraploid lines were collected after 90 days in vitro rooting culture and were evaluated to provide evidence of good qualities of tetraploid S. tonkinensis. RESULTS: The results showed that the highest percentage of tetraploid induction was 23.33% and occurred in the 0.2% (w/v) colchicine treatment for 30 h. Fifty lines of tetraploid plants were obtained and 12 of the 13 selected tetraploid lines exhibited higher productivity of total contents of matrine and oxymatrine when compared to controls. CONCLUSION: The data demonstrate that polyploidy induction can be beneficial for improving the medicinal value of S. tonkinensis. SUMMARY: Colchicine has a good in vitro induction effect on the tetraploid plants of Sophora tonkinensisThe leaf indices and stomatal apparatus of tetraploid plants were slightly larger than diploid plantsThe total content of matrine and oxymatrine of some tetraploid lines for 90-day-old in vitro rooting culture was higher than the diploid. Abbreviations used: MS medium: Murashige and Skoog medium; BAP: 6-benzylaminopurine; NAA: A-naphthaleneacetic acid; IAA: Indole-3-acetic acid; KT: Kinetin; IBA: Indole-3-butyric acid; ABT: Rooting power.

[Effect of Nutrient Solution in Soilless Cultivation on Growth, Antioxidase Activities and Amino Acid Contents of Nervilia fordii].

OBJECTIVE: To select the best formula for soilless cultivation of Nervilia fordii. METHODS: Four different formulas of nutrient solution on growth,antioxidase activities and amino acid contents were investigated. RESULTS: The concentration of 1/2 lettuce nutrient solution formula was the most propitious for the growth of Nervilia fordii, the antioxidase activities and amino acid contents were increased in the treatment of nutrient solution,and the highest amino acid content was observed in 1/2 dose of green leafy vegetables nutrient solution formula. CONCLUSION: The concentration of 1/2 lettuce nutrient solution formula is the optimal solution for growth of Nervilia fordii, the results of this study provides academic and technological basis for soilless cultivation of Nervilia fordii.

[Screening, identification and phosphate-solubilizing characteristics of Rahnella sp. phosphate-solubilizing bacteria in calcareous soil].

Several strains of phosphate-solubilizing bacteria were isolated and screened from the crop rhizosphere of calcareous soil in Shanxi Province of China. After repeated isolation and purification, the strain W25 with strong phosphate-solubilizing activity was obtained, and identified as Rahnella sp., based on the morphological, physiological and biochemical properties and the analysis of 16S rRNA gene sequence. Further studies on the W25 showed that the maximum phosphate-solubilizing capability of the W25 on tricalium phosphate, aluminum phosphate and ferric phosphate reached 385.5, 110.4 and 216.6 mg x L(-1), respectively. In the liquid culture with aluminum phosphate and ferric phosphate, the solubilized phosphorous by the W25 was significantly negatively correlated with the liquid pH, with the correlation coefficient being 0.56 and 0.81, respectively. Among the carbon and nitrogen sources, glucose and ammonium nitrate were the optimum for the solubilization of tricalium phosphate by W25. The utilization of carbon source was in the order of glucose > lactose > sucrose > mannitose > starch, and that of nitrogen source was in the order of ammonium nitrate > ammonium chloride > ammonium sulfate > potassium nitrate > sodium nitrate. Different nitrogen sources had greater effects on the production of organic acids by W25. Formic acid and acetic acid would be produced when the nitrogen source was NH4+, oxalic acid and succinic acid would be produced when the nitrogen source was NO3(-), and citric acid would be extra produced when the ammonium nitrate was used as the nitrogen source.

[Antagonism of Trichoderma spp. to fungi caused root rot of Sophora tonkinensis].

OBJECTIVE: To study the antagonism of Trichoderma spp. to fungi S9(Fusarium solani)which caused root rot of Sophora tonkinensis and discuss the further develop prospects of microbial biological control in soil-borne diseases on Chinese herbal medicines. METHODS: Antagonism of H2 (Trichoderma harsianum), M6 (Trichoderma viride) and K1 (Trichoderma koningii) to Fusarium solani were researched by growth rate and confront culture. And their mechanisms were discussed. RESULTS: H2 and M6 had obvious competitive advantage, the growth rate of which were 1.43-2.72 times and 1.43-1.95 times as S9 respectively. The space competitive advantage of K1 was relatively weak; the growth rate was slower than S9. The antagonism of three species of Trichoderma spp. to S9 was in varying degrees. The antagonism to S9 of M6 and H2 was better,the inhibition rate were 100% and 82.35% respectively, even cultivated S9 for three days in advance. And their inhibition indexes were both reached class I. The inhibition index and inhibition rate of K1 was respectively 46.36% and class IV. The Trichoderma spp. could cause S9 mycelium to appear some phenomenon just like fracture, constriction reduced, digestion, etc. which were observed under the microscope. CONCLUSION: Trichoderma harsianum and Trichoderma viride showed the further develop prospects in the fight against soil-borne disease on Chinese herbal medicines.

[Identification of pathogens causing root rot of Sophora tonkinensis].

OBJECTIVE: To identify the pathogens what caused of root rot, it can provide method of theoretical gist of integrated pest management of these kinds of diseases in the future. METHODS: Pathogens from rotten root of Sophora tonkinensis were isolated by tissue isolation. Their morphological characteristics were observed and rDNA-ITS sequence were sequenced, then analyzed by Blast in GenBank. RESULTS: Round colony in PDA medium. The aerial mycelium was thin, white, light gray and yellowish brown eustroma was on the surface of material. The surface of base material was flesh. Large number of small conidia ware oval, kidney-shaped, 8-16 microm x 2.5 -4 microm. And the large conidia just like Matt spore type, which had 3 to 5 septums. The length of rDNA-ITS of the fungi was 553 bp, which the ITS region sequences compared with the sequence of Fusarium solani (accession number: AB518683.1, AB470903.1, AB369488.1, AJ608989.1, GQ365154.1, EF152426.1), and Fusarium oxysporum (accession number: GQ922558.1, GQ922559.1, DQ452447.1) homology reached 99%. CONCLUSION: Combination of two identification methods,it arrived at the cause of root rot pathogen fungi was Fusarium solani.