14 research outputs found

    High Color Purity CsPbBr<sub>3</sub> Nanocrystals Prepared by a Heterogeneous Reaction System

    No full text
    All inorganic perovskite CsPbX3 (X = Cl, Br, and I) nanocrystals (NCs) have emerged as new semiconductor materials for light-emitting applications due to their high light absorption coefficient, tunable spectrum, and high photoluminescence quantum yields (PLQYs). However, owing to their burst nucleation and growth, the size distribution of CsPbX3 NCs prepared by the conventional homogeneous reaction system is wide, which affects their high color purity. Here, a heterogeneous reaction system was designed to prepare CsPbBr3 NCs with a narrow size distribution by controlling the nucleation and growth kinetics of CsPbBr3 NCs and eliminating the undesired Ostwald ripening effect. The synthesized CsPbBr3 NCs exhibit nearly a unit PLQY and a narrow size distribution. Benefiting from the tight ligands on the surface of NCs that can both stabilize the inorganic nuclei of CsPbBr3 NCs and passivate the Br vacancy defects of the NC surface, the obtained CsPbBr3 NCs have excellent optical stability. In particular, the PLQY of the CsPbBr3 NC colloidal dispersion can be as high as 86% even after 13 cycles of purification with methyl acetate

    Patchiness of phytoplankton and primary production in Liaodong Bay, China

    No full text
    <div><p>A comprehensive study of water quality, phytoplankton biomass, and photosynthetic rates in Liaodong Bay, China, during June and July of 2013 revealed two large patches of high biomass and production with dimensions on the order of 10 km. Nutrient concentrations were above growth-rate-saturating concentrations throughout the bay, with the possible exception of phosphate at some stations. The presence of the patches therefore appeared to reflect the distribution of water temperature and variation of light penetration restricted by water turbidity. There was no patch of high phytoplankton biomass or production in a third, linear patch of water with characteristics suitable for rapid phytoplankton growth; the absence of a bloom in that patch likely reflected the fact that the width of the patch was less than the critical size required to overcome losses of phytoplankton to turbulent diffusion. The bottom waters of virtually all of the eastern half of the bay were below the depth of the mixed layer, and the lowest bottom water oxygen concentrations, 3–5 mg L<sup>–1</sup>, were found in that part of the bay. The water column in much of the remainder of the bay was within the mixed layer, and oxygen concentrations in both surface and bottom waters exceeded 5 mg L<sup>–1</sup>.</p></div

    Contour maps and/or corresponding location maps of temperature (Panels A and B, in °C), Secchi-disk depth (Panels C and D, in meters), Secchi-disk depth associated with temperature (Panel E), and dissolved oxygen (DO, Panel F, in mg L<sup>–1</sup>).

    No full text
    <p>Contour maps and/or corresponding location maps of temperature (Panels A and B, in °C), Secchi-disk depth (Panels C and D, in meters), Secchi-disk depth associated with temperature (Panel E), and dissolved oxygen (DO, Panel F, in mg L<sup>–1</sup>).</p

    Relationship between DO concentrations and salinity (Panel A) and location of stations in three groups with different DO concentrations (Panel B).

    No full text
    <p>In Panels A and B, circle dots denote stations with high DO of more than 13 mg L<sup>–1</sup> at a salinity of 1 to low DO concentrations of 3–5 mg L<sup>–1</sup> at salinities of 16–26; Triangles and plus signs denote stations with DO concentrations of roughly 7–9 mg L<sup>–1</sup> and 9–11 mg L<sup>–1</sup>, respectively, in both cases at salinities of 20–28.</p

    Inter-Annual Variability of Area-Scaled Gaseous Carbon Emissions from Wetland Soils in the Liaohe Delta, China

    No full text
    <div><p>Global management of wetlands to suppress greenhouse gas (GHG) emissions, facilitate carbon (C) sequestration, and reduce atmospheric CO<sub>2</sub> concentrations while simultaneously promoting agricultural gains is paramount. However, studies that relate variability in CO<sub>2</sub> and CH<sub>4</sub> emissions at large spatial scales are limited. We investigated three-year emissions of soil CO<sub>2</sub> and CH<sub>4</sub> from the primary wetland types of the Liaohe Delta, China, by focusing on a total wetland area of 3287 km<sup>2</sup>. One percent is <i>Suaeda salsa</i>, 24% is <i>Phragmites australis</i>, and 75% is rice. While <i>S</i>. <i>salsa</i> wetlands are under somewhat natural tidal influence, <i>P</i>. <i>australis</i> and rice are managed hydrologically for paper and food, respectively. Total C emissions from CO<sub>2</sub> and CH<sub>4</sub> from these wetland soils were 2.9 Tg C/year, ranging from 2.5 to 3.3 Tg C/year depending on the year assessed. Primary emissions were from CO<sub>2</sub> (~98%). Photosynthetic uptake of CO<sub>2</sub> would mitigate most of the soil CO<sub>2</sub> emissions, but CH<sub>4</sub> emissions would persist. Overall, CH<sub>4</sub> fluxes were high when soil temperatures were >18°C and pore water salinity <18 PSU. CH<sub>4</sub> emissions from rice habitat alone in the Liaohe Delta represent 0.2% of CH<sub>4</sub> carbon emissions globally from rice. With such a large area and interannual sensitivity in soil GHG fluxes, management practices in the Delta and similar wetlands around the world have the potential not only to influence local C budgeting, but also to influence global biogeochemical cycling.</p></div

    Location of study sites and aerial distribution of habitat types sampled in the Liaohe Delta, China.

    No full text
    <p>Map highlights 31.6 km<sup>2</sup> of <i>Suaeda salsa</i> wetlands, 786 km<sup>2</sup> of <i>Phragmites australis</i> wetlands, and 2464.6 km<sup>2</sup> of rice paddy wetlands, as well as the location of our five wetland sites, including two in <i>Phragmites australis</i> (Phrag1, Phrag2), two in <i>Suaeda salsa</i> (Suaeda1, Suaeda2), and one in rice paddy (Rice). Aerial distribution data are from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160612#pone.0160612.ref030" target="_blank">30</a>], and the shape file represents 2011 classifications (China Geological Survey).</p

    Hydrographs for wetland study sites in the Liaohe Delta.

    No full text
    <p>a) Water level patterns for 2012, b) water level patterns for 2013, and c) water level patterns for 2014 from our five wetland sites, including two <i>Phragmites australis</i> sites (Phrag1, Phrag2), two <i>Suaeda salsa</i> sites (Suaeda1, Suaeda2), and one rice paddy site (Rice) in the Liaohe Delta, China. Missing data from Suaeda1 and Suaeda2 at the beginning of 2013, and for Suaeda2 beginning in August of 2014, represent datalogger failure. Consistent water levels <-30 cm for Phrag1 and Rice indicate times when water levels were below pressure transducers embedded in the soils.</p
    corecore