47 research outputs found

    Phase Behavior of Biocompatible Microemulsions Formed by Sucrose Stearate in the Presence of Sodium Deoxycholate

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    Biocompatible microemulsion has received increased interest among other self-assembly systems. On the basis of the phase behavior of sucrose stearate (S1570)/isopropyl alcohol/isoamyl acetate/water with α = 0.5 was investigated at 313 K, and found that emulsification occurs in this system. When the aqueous phase is changed to NaCl solution, the three-phase body appears after the addition of sodium deoxycholate (NaDC) to the S1570 system, And with a less amount of NaDC, the solubilization capacity of the mixed surfactant system is higher. On the other hand, the phase behavior of S1570/NaDC/isopropyl alcohol/isoamyl acetate/NaCl was studied at different temperatures and found that the addition of NaDC changes the temperature sensitivity of the microemulsion system formed using sucrose ester, and with increasing temperature the solubilization capacity of the system increases. The influence of the concentration of NaCl, chain lengh of the oil phase, and oil–water ratio on the phase behaviors was also discussed. Increasing the concentration of NaCl increases the solubilization capacity of the mixed system. With the chain length of oil phase increasing, the monomeric solubility in oil (<i>S</i><sub>1</sub>) and the interfacial concentration (<i>S</i><sub>1</sub><sup>S</sup>) of isopropyl alcohol are all increased, which in turn decreases the solubilization capacity of these systems

    Growth of a cohort of 100 <i>Celtis zenkeri</i> trees with a uniform initial diameter distribution.

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    <p>Projection time is yr. The time step of the matrix model is yr and the class width is column-wise (A) cm, (B) 0.9994 cm, and (C) 2.4985 cm. The top panel shows images of the transitions matrices between the initial and final times (i.e. the annual transition matrices raised to the power of ), where the starting class is column-wise, the ending class is row-wise, and the transition rates between classes are shown using heat colors (from white = zero to red = the highest values). The bottom panel shows the predicted dbh distributions: dotted line = initial dbh distribution (uniform across 10–14.997 cm); solid line = final dbh distribution according to the McKendrick continuous model; shaded bins = final dbh distribution according to the Usher matrix model.</p

    Variance of the dbh growth rate versus one-year dbh increment for 53 tree species.

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    <p>Notice that axes are in logarithmic scale. The line is the regression line on log-transformed data.</p

    Distribution across 53 species of the amplitude of variations of the population growth rate .

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    <p>Left boxplot: variations of when the class width varies from 1 to 10 cm, where . Right boxplot: amplitude of the 95% confidence interval of the estimate of for cm.</p

    Total Synthesis of Dictyodendrins B and E

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    The concise synthesis of the novel telomerase inhibitors dictyodendrins B and E was completed in only 9 and 11 steps (longest linear sequence). The highly convergent strategy employed a palladium-catalyzed Larock indole synthesis and a palladium-mediated one-pot consecutive Buchwald–Hartwig amination/C–H activation reaction as key steps. The present synthesis exhibits respectable levels of atom-, redox-, and step-economy

    Potential feedback of recent vegetation changes on summer rainfall in the Sahel

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    <p>The Sahel region of Northern Africa is home to more than 50 million people for whom summer rainfall is a crucial water resource in terms of food security and societal stability. Using satellite-based Normalized Difference Vegetation Index (NDVI) and gridded observational precipitation records during 1982–2012, we detected a significant increase (<i>p</i>-value < 0.01) in both vegetation greenness and monsoon rainfall over the Sahel since the early 1980s. A significant positive association between NDVI and precipitation was observed for most of the Sahel during the boreal summer. In further efforts to examine the potential causal association behind the positive correlation, we found that summer vegetation greenness Granger-causes summer rainfall in the Sahel. Regarding the physical process behind this identified Granger causality, we inferred that significantly increasing latent heat flux and specific humidity resulted in increasing summer rainfall during the years of high NDVI in the Sahel. A significant increase in the percentage of land used for crops and pastures was a potential cause of the recent vegetation change. Our findings indicated that the positive effect of vegetation cover through agricultural activities on regional precipitation could lead to a positive feedback between the vegetation and climate in the water-limited Sahel region.</p

    Total Synthesis of Dictyodendrins B and E

    No full text
    The concise synthesis of the novel telomerase inhibitors dictyodendrins B and E was completed in only 9 and 11 steps (longest linear sequence). The highly convergent strategy employed a palladium-catalyzed Larock indole synthesis and a palladium-mediated one-pot consecutive Buchwald–Hartwig amination/C–H activation reaction as key steps. The present synthesis exhibits respectable levels of atom-, redox-, and step-economy

    Total Synthesis of Dictyodendrins B and E

    No full text
    The concise synthesis of the novel telomerase inhibitors dictyodendrins B and E was completed in only 9 and 11 steps (longest linear sequence). The highly convergent strategy employed a palladium-catalyzed Larock indole synthesis and a palladium-mediated one-pot consecutive Buchwald–Hartwig amination/C–H activation reaction as key steps. The present synthesis exhibits respectable levels of atom-, redox-, and step-economy

    Data_Sheet_1_Spatiotemporal trends of black walnut forest stocking under climate change.docx

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    Basal area is a key measure of forest stocking and an important proxy of forest productivity in the face of climate change. Black walnut (Juglans nigra) is one of the most valuable timber species in North America. However, little is known about how the stocking of black walnut would change with differed bioclimatic conditions under climate change. In this study, we projected the current and future basal area of black walnut. We trained different machine learning models using more than 1.4 million tree records from 10,162 Forest Inventory and Analysis (FIA) sample plots and 42 spatially explicit bioclimate and other environmental attributes. We selected random forests (RF) as the final model to estimate the basal area of black walnut under climate change because RF had a higher coefficient of determination (R2), lower root mean square error (RMSE), and lower mean absolute error (MAE) than the other two models (XGBoost and linear regression). The most important variables to predict basal area were the mean annual temperature and precipitation, potential evapotranspiration, topology, and human footprint. Under two emission scenarios (Representative Concentration Pathway 4.5 and 8.5), the RF model projected that black walnut stocking would increase in the northern part of the current range in the USA by 2080, with a potential shift of species distribution range although uncertainty still exists due to unpredictable events, including extreme abiotic (heat, drought) and biotic (pests, disease) occurrences. Our models can be adapted to other hardwood tree species to predict tree changes in basal area based on future climate scenarios.</p

    Diarylheptanoids from the fresh pericarps of <i>Juglans sigillata</i>

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    <p>One new diarylheptanoid (3<i>S</i>)-3′, 4″-epoxy-1-(4′-hydroxylphenyl)-7-(3″-hydroxylphenyl) heptane-3-hydroxy (<b>1</b>), together with eleven known ones (<b>2</b>–<b>12</b>), was isolated from the fresh pericarps of <i>Juglans sigillata</i>. Their structures were elucidated on the basis of extensive spectroscopic methods, including HR-ESI-MS, 1D and 2D-NMR. All isolates were evaluated for their cytotoxic activities <i>in vitro</i> against the growth of human cancer cells lines HT-29 and MCF-7 by MTT assay.</p
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