[Relationship between vegetation C, N, P stoichiometry and species diversity in sand land.] / æ²™åœ°æ¤è¢«ç¢³æ°®ç£·åŒ–å­¦è®¡é‡ç‰¹å¾ä¸Žç‰©ç§å¤šæ ·æ€§çš„å ³ç³».

Vegetation stoichiometry represents plant nutrition limitation status. Whether it can affect the species diversity of plant community remains to be explored. In this study, we examined plant carbon (C), nitrogen (N), phosphorus (P) concentrations and stoichiometry, and further analyzed the relationship between stoichiometry and species diversity in Artemisia ordosica community and Salix psammophila community in sand land of the Ningxia Habahu National Nature Reserve. The results showed that, for the S. psammophila community growing in mobile and semi-fixed sand dunes, there was a significant negative correlation between Simpson index and vegetation C/N ratio, but no significant correlation between Simpson index and vegetation N/P ratio. For A. ordosica community distributed in semi-fixed and fixed dunes, the Shannon index had a significant positive correlation with vegetation N/P ratio and a significant negative correlation with vegetation C/N ratio. Combined the vegetation stoichiometry with the results of regression analysis (RDA), P concentration and thus N/P ratio had different influences on the species diversity for A. ordosica community and S. psammophila community. Our results showed that vegetation stoichiometry has an important influence on species diversity of plant community in sand land.

[Adaptability of Helianthus annuus seedlings to crude oil pollution in soil and its improvement measures under salinization stress].

To explore the adaptability of plant under salt stress to crude oil pollution of soil and improvement measures, a pot experiment of Helianthus annuus seedlings was conducted using orthogonal experiment method with crude oil-sodium chloride-desulfurization gypsum and cinder-zeolite-desulfurization gypsum-sawdust. The results showed that, with the increase of soil crude oil concentration, the relative growth rate (RGR) of plant height, RGR of aboveground biomass and root N: P ratios of H. annuus seedlings decreased significantly, while the activity of SOD and CAT increased at first and then decreased significantly. The RGR of plant height and aboveground biomass significantly increased (P < 0.05), while the activity of SOD decreased gradually with the increase of the volume fraction of sawdust, indicating that sawdust had the most significant effect in comparison with cinder, zeolite, desulfurization gypsum under salinization condition. The crude oil pollution of soil could decrease the relative growth rate of H. annuus seedling, and sawdust could reduce the influence of crude oil pollution on plant growth under salt stress.

[Analysis on preparation and characterization of asiaticoside-loaded flexible nanoliposomes].

Asiaticoside is a compound extracted from traditional Chinese medicine Centella asiatica, and mainly used in wound healing and scar repair in clinical, with notable efficacy. However, its poor transdermal absorption and short action time restrict its wide application. In this experiment, the reserve-phase-extrusion-lyophilization method was conducted to prepare the lyophilized asiaticoside-loaded flexible nanoliposomes (LAFL). Its characteristics including electron microscope structure, particle size, Zeta potential, entrapment rate, drug-loading rate, stability and drug release were determined with the intelligent transdermal absorption instrument. LAFL were white spheroids, with pH, particle size and zeta potential of 7. 03, 70. 14 nm and - 36. 5 mV, respectively. The average entrapment rate of the 3 batch samples were 31. 43% , and the average asiaticoside content in 1 mg lyophilized simple was 0. 134 mg. The results indicated that LAFL have good physicochemical properties and pharmaceutical characteristics, with an improved transdermal performance.

[Features of calcium crystals and calcium components in 54 plant species in salinized habitats of Tianjin].

Plant calcium (Ca) is composed of dissociated Ca2+ and easily soluble, slightly soluble, and hard soluble combined Ca salts. The hard soluble Ca salts can often engender Ca crystals. To understand the Ca status in different growth form plants in salinized habitats, 54 plant species were sampled from the salinized habitats in Tianjin, with the Ca crystals examined by microscope and the Ca components determined by sequential fractionation procedure. More Ca crystals were found in 38 of the 54 plant species. In 37 of the 38 plant species, drusy and prismatic Ca oxalate crystals dominated, whereas the cystolith of Ca carbonate crystal only appeared in the leaves of Ficus carica of Moraceae. The statistics according to growth form suggested that deciduous arbors and shrubs had more Ca oxalate crystal, liana had lesser Ca oxalate crystal, and herbs and evergreen arbors had no Ca oxalate crystal. From arbor, shrub, liana to herb, the concentration of HCl-soluble Ca decreased gradually, while that of water soluble Ca was in adverse. The concentration of water soluble Ca in herbs was significantly higher than that in arbors and shrubs. This study showed that in salinized habitats, plant Ca crystals and Ca components differed with plant growth form, and the Ca oxalate in deciduous arbors and shrubs played an important role in withstanding salt stress.