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991.
Hui Xiong Jinping Fu Hanjing Sun Enfu Wang Yunhui Ding Guobin Ren Qiufang Jing Fuzheng Ren 《AAPS PharmSciTech》2017,18(8):2889-2897
Micro-particles of 17β-estradiol (ED) were prepared with polyvinylpyrrolidone (PVP) by in situ pH-dependent solubility technique. Products were characterized using multiple instruments, and molecular interactions between ED and PVP were explored. Powder X-ray diffraction and thermal analysis revealed crystalline ED in the micro-particles is hemihydrated. PVP was also present in the micro-particles. Laser particle size analysis and scanning electron microscopy revealed thin slice morphology, which might have resulted from the influence of PVP. Moreover, the results of contact angle, specific surface area, and dynamic vapor sorption showed that the surface properties of products were improved. These physicochemical properties of the micro-particles resulted in an obvious improvement in dissolution rate. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance revealed hydrogen bonding between ED and PVP. A method was established for the preparation of micro-particles through the addition of PVP during the reaction process. 相似文献
992.
Traditional neonicotinoid insecticides are used worldwide. Paichongding (IPP), as a novel neonicotinoid pesticide, has been widely used in China. However, the ecotoxicity of IPP to non-target invertebrates in soil ecosystem has not been reported yet. In this study, acute toxicity of IPP to earthworm Eisenia fetida, as well as the antioxidant response after IPP exposure, was evaluated. In the filter paper contact test, the LC50 at 24 hr and 48 hr for IPP were 14.98 μg/cm2 and 7.59 μg/cm2, respectively. In artificial soil test, the LC50 (lethal concentration) at 14 days and 28 days for IPP were 541.07 mg/kg and 238.51 mg/kg, respectively. The LC50 of IPP is much higher than that of traditional neonicotinoid insecticides. However, earthworm body weight assessment demonstrated that the growth of earthworm was inhibited by extended exposure to IPP at sublethal doses. The activities of antioxidative enzymes superoxide dismutase and catalase in earthworms were significantly induced after IPP exposure. Malondialdehyde, a biomarker of lipid peroxidation, was also increased after IPP exposure. Although the results indicated that IPP had potentially adverse effect on earthworms, its toxicity was much lower than traditional neonicotinoids. 相似文献
993.
一株产碱性蛋白酶菌株的筛选鉴定及酶学特性研究 总被引:4,自引:0,他引:4
【目的】从丝茅草中筛选得到产蛋白酶菌株并研究驯化过程中微生物群落结构,以及探究该菌株的生长特性和蛋白酶的酶学特性。【方法】通过高通量测序探究来源于丝茅草的菌株在不同培养条件下细菌种类及丰度,通过选择性培养基来筛选能够分解酪素并产生蛋白酶的菌株,通过单因素试验方法确定环境因子对菌株生长和蛋白酶活性的影响。【结果】微生物群落结构在基础培养基和牛肉膏蛋白胨培养基中不同。通过含酪素的选择性培养基里筛选到1株产蛋白酶菌株H-16,经生理生化试验和16S r DNA鉴定知该菌株属于Escherichia marmotae,菌株H-16能产生分子量为70 k Da左右的单亚基蛋白酶。胰蛋白胨、蔗糖、30°C或35°C、p H 7分别为菌株生长的最适氮源、碳源、温度和p H。菌株H-16分泌的蛋白酶最适p H为6–8,在50°C及6%盐度以下酶活性几乎不受影响。此外,Cu(II)和Ag(I)等金属离子能够抑制蛋白酶的活性。【结论】该菌株H-16为嗜中温菌株,能够产生碱性蛋白酶。 相似文献
994.
Lilin Zhu Zhicheng Xiong Wei Yu Xiaolin Tian Yan Kong Cheng Liu Shouyu Wang 《Plasmonics (Norwell, Mass.)》2017,12(1):33-38
A polarization-controlled tunable plasmonic lens which can generate different multi-focal combinations with exciting sources of left and right circular polarizations is proposed in this paper. Both position and intensity of each focal point can be adjusted by modulating the structure of the plasmonic lens. It is believed that the polarization-controlled tunable plasmonic multi-focal lens can be potentially used for optical switches and multi-channel couplers in future logic photonic and plasmonic systems. 相似文献
995.
Shiwen Luo Bin Li Dongsheng Xiong Duluo Zuo Xinbing Wang 《Plasmonics (Norwell, Mass.)》2017,12(2):223-227
A high performance plasmonic sensor based on a metal-insulator-metal (MIM) waveguide coupled with a double-cavity structure consisting of a side-coupled rectangular cavity and a disk cavity is proposed. The transmission characteristics of the rectangular cavity and disk cavity are analyzed theoretically and the improvements of performance for the double-cavity structure compared with a single cavity are studied. The influence of structural parameters on the transmission spectra and sensing performance are investigated in detail. A sensitivity of 1136 nm/RIU with a high figure of merit of 51,275 can be achieved at the resonant wavelength of 1148.5 nm. Due to the high performance and easy fabrication, the proposed structure may be applied in integrated optical circuits and on-chip nanosensors. 相似文献
996.
Hao-qin Xiong 《Journal of Plant Ecology》2010,3(2):131
Aims Most plants are clonal in nature. Clonal ramets can share water, nutrients and photosynthate, especially when they experience patchy resources. Patch contrast (i.e. a difference in resources among patches) and patch direction (i.e. source–sink relations) are among the basic attributes of spatial patchiness. Here, I hypothesize that young established ramets in nutrient-rich patches support old ramets in nutrient-poor patches when ramets are subjected to different patch contrasts and patch directions.Methods In a greenhouse experiment, old and young ramets of Glechoma longituba were grown in four combinations consisting of patch contrast and patch direction. Minus patch direction refers to a patch combination in which parent ramets grow in nutrient-rich patches while connected daughter ramets grow in nutrient-poor ones and plus patch direction is the opposite direction. I measured photosynthesis and fluorescence traits, harvested all ramets, took morphological measures, weighed their dry mass and determined their nutrient uptake and use.Important findings For parental ramets of G. longituba, patch contrast and patch direction and their interactions had no significant effects on net photosynthetic rate, maximal fluorescence yield, photochemical quenching (quenching refers to any process which decreases the fluorescence intensity of a given substance), non-photochemical quenching, nutrient uptake, biomass and stolon weight ratio. Patch direction alone significantly affected root weight ratio. Large patch contrast enhanced N use efficiency (NUE) and P use efficiency (PUE); plus patch direction decreased NUE, but increased PUE; the patch contrast by patch direction interaction affected PUE and K use efficiency (KUE). There were significant interactions between patch direction and patch contrast on PUE and KUE. It is concluded that soil nutrient patchiness may influence nutrient use strategies, but not nutrient uptake, photosynthesis and growth of parent ramets of G. longituba connected to daughter ramets, and that patch contrast and patch direction jointly affect PUE and KUE. 相似文献
997.
在室内人工模拟潮汐, 研究了4种盐度(0、10‰、25‰和35‰, 分别代表淡水、低盐、中盐和高盐)下秋茄(Kandelia candel)凋落叶分解过程中物质与能量动态的差异。结果表明, 高盐处理下的失重率和平均分解速率显著低于淡水和低盐处理, 而高盐下的半分解理论值则高于其他处理; 盐度对分解过程中的残叶氮磷变化动态有显著影响, 其中, 残叶氮的释放速率在实验后期会随着盐度的升高而上升, 高盐度下残叶总氮含量显著低于低盐或淡水处理; 而在分解第1周, 淡水或低盐处理能加速磷的释放, 但中高盐度残叶中总磷含量最终会低于淡水和低盐处理; 盐度同样能对残叶热值产生显著影响, 淡水和低盐处理下的碎屑热值要显著高于高盐处理下的残叶热值, 但不同盐度下分解的能量损失差异不显著。 相似文献
998.
Hongyun?Shen Hongchun?Xiong Xiaotong?Guo Pengfei?Wang Penggen?Duan Lixia?Zhang Fusuo?Zhang Yuanmei?ZuoEmail author 《Planta》2014,239(5):1065-1077
Peanut (Arachis hypogaea L.) is an important legume providing edible proteins and N2 fixation. However, iron deficiency severely reduces peanut growth in calcareous soils. The maize/peanut intercropping effectively improves iron nutrition and N2 fixation of peanut under pot and field conditions on calcareous soils. However, little was known of how intercropping regulates iron transporters in peanut. We identified AhDMT1 as a Fe2+ transporter which was highly expressed in mature nodules with stronger N2 fixation capacity. Promoter expression analysis indicated that AhDMT1 was localized in the vascular tissues of both roots and nodules in peanut. Short-term Fe-deficiency temporarily induced an AhDmt1 expression in mature nodules in contrast to roots. However, analysis of the correlation between the complex regulation pattern of AhDmt1 expression and iron nutrition status indicated that sufficient iron supply for long term was a prerequisite for keeping AhDmt1 at a high expression level in both, peanut roots and mature nodules. The AhDmt1 expression in peanut intercropped with maize under 3 years greenhouse experiments was similar to that of peanut supplied with sufficient iron in laboratory experiments. Thus, the positive interspecific effect of intercropping may supply sufficient iron to enhance the expression of AhDmt1 in peanut roots and mature nodules to improve the iron nutrition and N2 fixation in nodules. This study may also serve as a paradigm in which functionally important genes and their ecological significance in intercropping were characterized using a candidate gene approach. 相似文献
999.
Soil fungi fill pivotal ecological roles in biogeochemical processes, particularly dominating decomposition of lignin. Little is known, however, about the responses of different fungal groups to climate warming with respect to bacteria. In this study, using barcode pyrosequencing, we showed that short-term (15 months) of field exposure of an alpine meadow to warming (elevated 1 and 2 °C) did not markedly alter the overall soil fungal community structures and α-diversity on Tibetan Plateau, but the average β-diversity dramatically decreased in response to warming. However, soil respiration rates were stimulated in the growing season, which significantly (P?0.001) correlated with soil temperature. Particularly, warming triggered dramatic shifts in the community structure of dominate Ascomycota and rare taxa (relative abundance?0.1 %). In addition, the abundances of specific Basidiomycota-affiliated members significantly increased, while Ascomycota showed a range of responses to warming. Collectively, we conclude that the fungal communities are resistant to short-term warming, though variations are observed in certain species and rare taxa. This report indicates that changes in a relatively small subset of the soil fungal community are sufficient to produce substantial changes in function, such as CO2 efflux rates. 相似文献
1000.
Shi P Li D Chen H Xiong Y Tian C 《Biochemical and biophysical research communications》2011,414(2):379-383
Membrane proteins play an essential role in cellular metabolism, transportation and signal transduction across cell membranes. The scarcity of membrane protein structures has thus far prevented a full understanding of their molecular mechanisms. Preliminary topology studies and residue solvent exposure analysis have the potential to provide valuable information on membrane proteins of unknown structure. Here, a (19)F-containing unnatural amino acid (trimethylfluoro-phenylalanine, tfmF) was applied to accomplish site-specific (19)F spin incorporation at different sites in diacylglycerol kinase (DAGK, an Escherichia coli membrane protein) for site-specific solvent exposure analysis. Due to isotope effect on (19)F spins, a standard curve for (19)F-tfmF chemical shifts was drawn for varying solvent H(2)O/D(2)O ratios. Further site-specific (19)F solvent isotope shift analysis was conducted for DAGK to distinguish residues in water-soluble loops, interfacial areas or hydrophobic membrane regions. This site-specific solvent exposure analysis method could be applied for further topological analysis of other membrane proteins. 相似文献