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    Synthesis of Conformationally Constrained Esters and Amines by Pd-Catalyzed α-Arylation of Hindered Substrates

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    The α-arylation of sterically hindered silyl ketene acetals (SKAs) with sterically hindered aryl bromides occurs efficiently using Pd[P(t-Bu)3]2 as the optimal catalyst and ZnF2 as a promoter. Less sensitive P(t-Bu)3-based catalysts could be also employed but showed a lower activity. The reaction showed a broad scope with regard to both coupling partners, including heteroaryl bromides and cyclic SKAs. It also proved to be scalable to multigram quantities, which allowed us to further transform the ester group and to access conformationally constrained benzyl- and phenethylamines, highly sought-after building blocks for the synthesis of new agrochemicals

    Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy

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    Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19 nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32–56 nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general

    Effects of seed fermentation method on seed germination and vigor in the oleaginous gourd Lagenaria siceraria (Molina) Standl.

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    Supplying high quality seed to rural farmers is the basic requirement for the sustainable development of agriculture in developing countries. The present study was conducted to examine the influence of Lagenaria siceraria seed fermentation method on seed germination and vigor. Three seed fermentation methods (fermented in ambient air, plastic bag stored in ambient or in plastic bag buried) were tested on two cultivars during two years. Seed germination and vigor were better when fermentation was conducted in anaerobic, darkness, and at low temperature. Low seed quality was observed in unfermented seed, suggesting the occurrence of postharvest maturity in L. siceraria. Seed quality did not vary between cultivars. Regardless of the fermentation process and cultivars used, the best seed and seedling qualities were observed when the amount of rainfall during the experiment period was high, suggesting that wet soil is necessary for an on farm reliable evaluation of seed fermentation method in the bottle gourd L. siceraria.Keywords: Cucurbit, egussi, maturity, minor crops, oilseed, seedling, viability
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