757 research outputs found

    High Capacity of Nutrient Accumulation by Invasive Solidago canadensis in a Coastal Grassland

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    BackgroundSolidago canadensis is a notorious invasive species from North America that is spreading across East China. It is invading some coastal grasslands and replacing native grass species. The effects of the S. canadensis invasion on soil nutrient cycling in the grasslands remain unclear. This study examined the effects of the invasion of S. canadensis on macronutrient accumulation in species aboveground part and soil.MethodsAboveground biomass, macronutrient (N, P, and K) pools in biomass, litter mass and decomposition rates, soil macronutrient availability and soil microbial biomass and enzyme activity that were related to nutrient transformation were compared between plots invaded by S. canadensis and uninvaded plots dominated by three different native grass species: Phacelurus latifolius, Phragmites australis, and Imperata cylindrica.ResultsS. canadensis had higher aboveground biomass, higher leaf N, P, and K concentrations, and consequently, a larger macronutrient pool size in the standing biomass. S. canadensis also produced more litter with higher N, P, and K concentrations and faster decomposition rates. The S. canadensis invasion did not change the total N, P, and K concentration in the topsoil (0–10 cm), but the invasion did increase their availability. The S. canadensis invasion did not increase the total soil organic matter (TSOM) content but did increase the soil microbial biomass and the activities of urease, alkaline phosphatase, invertase, amylase, and glucosidase in the topsoil.ConclusionThe invasion of S. canadensis accelerates the macronutrient cycling rate via increases in aboveground productivity and nutrient accumulation in standing biomass, faster nutrient release from litter and higher soil microbial activity. An enhanced nutrient cycling rate may further enhance its invasiveness through a positive feedback on soil processes

    Characterization of A- and B-type starch granules in Chinese wheat cultivars

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    AbstractStarch is the major component of wheat flour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultivars, and to compare structure and functionality of starches in four leading cultivars Zhongmai 175, CA12092, Lunxuan 987, and Zhongyou 206. A wide variation in volume percentages of A- and B-type starch granules among genotypes was observed. Volume percentages of A- and B-type granules had ranges of 68.4–88.9% and 9.7–27.9% in the first cropping seasons, 74.1–90.1% and 7.2–25.3% in the second. Wheat cultivars with higher volume percentages of A- and B-type granules could serve as parents in breeding program for selecting high and low amylose wheat cultivars, respectively. In comparison with the B-type starch granules, the A-type granules starch showed difference in three aspects: (1) higher amount of ordered short-range structure and a lower relative crystallinity, (2) higher gelatinization onset (To) temperatures and enthalpies (ΔH), and lower gelatinization conclusion temperatures (Tc), (3) greater peak, though, and final viscosity, and lower breakdown viscosity and pasting temperature. It provides important information for breeders to develop potentially useful cultivars with particular functional properties of their starches suited to specific applications

    Tris[2-(2-pyridylimino­meth­yl)phenol­ato(0.67−)]europium(III) nitrate

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    The title compound, [Eu(C12H9.33N2O)3]NO3, was obtained by the reaction of Eu(NO3)·3H2O and the Schiff base ligand 2-(2-pyridylimino­meth­yl)phenol. The Eu atom is located on a threefold rotation axis and is nine-coordinated by three tridentate Schiff base ligands in a distorted tricapped trigonal-prismatic geometry. The O atom at the phenol hydr­oxy group is partially deprotonated and the H atoms are modelled with one-third occupancy according to the space group R . Offset face-to-face π–π [centroid–centroid distance = 3.886 (3) Å] and edge-to-face C—H⋯π inter­actions are found between adjacent mol­ecules. An intra­molecular O—H⋯N hydrogen bond is also present

    Effects of meteorological factors on the incidence of meningococcal meningitis

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    Background and Objectives: Substantial climate changes have led to the emergence and re-emergence of various infectious diseases worldwide, presenting an imperative need to explore the effects of meteorological factors on serious contagious disease incidences such as that of meningococcal meningitis (MCM).Methods: The incidences of MCM and meteorology data between 1981 and 2010 were obtained from Chaoyang city. Structure Equation Modeling was used to analyze the relationships between meteorological factors and the incidence of MCM, using the LISREL software.Results: The SEM results showed that Adjusted Goodness of Fit Index (AGFI) = 0.30, Goodness of Fit Index (GFI) = 0.63, and Root Mean Square Error of Approximation (RMSEA) = 0.31. Humidity and temperature both had negative correlations with MCM incidence, with factor loads of -0.32 and -0.43, while sunshine was positively correlated with a factor load of 0.42. For specific observable variables, average air pressure, average evaporation, average air temperature, and average ground temperature exerted stronger influence, with item loads between observable variables and MCM incidence being -0.42, 0.34, -0.32, and -0.32 respectively.Conclusion: Public health institutions should pay more attention to the meteorological variables of humidity, sunshine, and temperature in prospective MCM control and prevention.Keywords: Meningococcal meningitis, Neisseria meningitidis, epidemiology, humidity, temperature, sunshine, meteorological variables, structure equation mode

    Bis[4-(2-hydroxy­benzyl­amino)phen­yl] ether

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    The title compound, C26H24N2O3, was synthesized by reduction of the corresponding Schiff base. The mol­ecule does not possess crystallographic or non-crystallographic symmetry. The dihedral angle between the oxygen-bridged benzene rings is 67.98 (8)°. Both hydroxyl groups are involved in O—H⋯O intra­molecular hydrogen bonding. The mol­ecules are linked into a two-dimensional network parallel to the (010) plane by N—H⋯O hydrogen bonds

    Stromal Derived Factor-1/CXCR4 Axis Involved in Bone Marrow Mesenchymal Stem Cells Recruitment to Injured Liver

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    The molecular mechanism of bone marrow mesenchymal stromal stem cells (BMSCs) mobilization and migration to the liver was poorly understood. Stromal cell-derived factor-1 (SDF-1) participates in BMSCs homing and migration into injury organs. We try to investigate the role of SDF-1 signaling in BMSCs migration towards injured liver. The expression of CXCR4 in BMSCs at mRNA level and protein level was confirmed by RT-PCR, flow cytometry, and immunocytochemistry. The SDF-1 or liver lysates induced BMSCs migration was detected by transwell inserts. CXCR4 antagonist, AMD3100, and anti-CXCR4 antibody were used to inhibit the migration. The Sprague-Dawley rat liver injury model was established by intraperitoneal injection of thioacetamide. The concentration of SDF-1 increased as modeling time extended, which was determined by ELISA method. The Dir-labeled BMSCs were injected into the liver of the rats through portal vein. The cell migration in the liver was tracked by in vivo imaging system and the fluorescent intensity was measured. In vivo, BMSCs migrated into injured liver which was partially blocked by AMD3100 or anti-CXCR4 antibody. Taken together, the results demonstrated that the migration of BMSCs was regulated by SDF-1/CXCR4 signaling which involved in BMSCs recruitment to injured liver
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