78 research outputs found

    A new chromone and a new aliphatic ester isolated from <i>Daldinia eschscholtzii</i>

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    <p>A new chromone and a new aliphatic ester were isolated from the EtOAc extract of myceliums of <i>Daldinia eschscholtzii</i>. Their structures were elucidated as (<i>R</i>)-5-hydroxy-8-methoxy-2-methylchroman-4-one (<b>1</b>) and (<i>E</i>)-6-(non-3-en-1-yl) -2<i>H</i>-pyran-2-one (<b>2</b>) by interpretation of the spectroscopic evidence.</p

    The Role of Stream Water Carbon Dynamics and Export in the Carbon Balance of a Tropical Seasonal Rainforest, Southwest China

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    <div><p>A two-year study (2009 ∼ 2010) was carried out to investigate the dynamics of different carbon (C) forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN), southwest China. The seasonal volumetric weighted mean (VWM) concentrations of total inorganic C (TIC) and dissolved inorganic C (DIC) were higher, and particulate inorganic C (PIC) and organic C (POC) were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC) and dissolved organic C (DOC) were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT), only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC) export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha<sup>−1</sup> yr<sup>−1</sup>, about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest.</p> </div

    Annual dynamics of ratio of stream carbon export to net ecosystem CO<sub>2</sub> exchange (NEE).

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    <p>(a) Annual dynamics of NEE <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056646#pone.0056646-Zhang1" target="_blank">[19]</a> and the sum of NEE and TC exported by headwater stream. (b) Annual dynamics of ratios of annual flux of DIC (DIC: NEE), DOC (DOC: NEE), PIC (PIC: NEE), and POC (POC: NEE) to NEE.</p

    Study site description in Xishuangbanna tropical seasonal rainforest, Southwest China.

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    <p>(a) Location of the study area (indicated by the black star). (b)The catchment site description was from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) that is a product of METI and NASA.</p

    Aryl-tetralin-type lignan isolated from <i>Sanguisorba officinalis</i>

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    <p>Three aryl-tetralin-type lignans, including 2 previously undescribed compounds, were isolated from the root of <i>Sanguisorba officinalis</i>. The structures of the new compounds were elucidated by 1D- and 2D-NMR spectroscopic analyses and mass spectrometry. Experimental and calculated ECD were used to determine the absolute configurations. The isolated compounds were evaluated for cytotoxicity against two cell lines (MV4-11 and MDA-MB-231) and compound <b>1</b> exhibited moderate growth inhibition against MDA-MB-231 cell line with IC<sub>50</sub> value of 15.76 μM.</p
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