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Abstract: The impact of different mixing methods on flow instability in capillary extrusion was examined using binary mixtures of linear low‐density polyethylene with different molecular weights. The polymers were blended using a single‐screw extruder, a twin‐screw extruder, and a twin‐screw mixer. The onset of flow instability changed depending on the mixing method used, even though their linear viscoelastic properties were almost identical. The mixtures that were subjected to mixing methods with weak mixing capability exhibit sharkskin failure even at low shear stress and low values of the maximum draw ratio without rupture in the molten state. The results suggested that mechanically weak points were present, which led to cohesive failure at the strand surface following abrupt stretching at the die exit (i.e., sharkskin failure). In contrast, the mixture that was subjected to thorough mixing exhibited smooth surface at high shear stress and a large maximum draw ratio. [ABSTRACT FROM AUTHOR]

Ellipticine, olivacine, and their five reduced natural variants were synthesized via a palladium-catalyzed tandem cyclization/cross-coupling reaction as the key step. In addition, a previously unknown conformer of janetine was obtained through conformational inversion of the D ring in janetine. Because there are few synthetic approaches for reduced natural variants, little is known about the biological activities of these compounds. Six synthetic natural alkaloids and five of their derivatives were evaluated for their antiproliferative activity against HCT-116 and HL-60 cells. The activities of variants with the D-reduced ring or without the C(11)-Me group were lower than those of ellipticine. The conformer of guatambuine showed higher activities than guatambuine. [ABSTRACT FROM AUTHOR]

The regioselective synthesis of pyrano[3,2- e ]indole alkaloid fontanesine B by two different cyclizations is described. The complete regioselectivity is controlled by the C4 Pictet-Spengler cyclization, in which an iminium ion acts as a transient directing (TDG) group. Furthermore, carbolines were constructed by a new Bischler-Napieralski-type cyclization, in which an unprecedented trichloromethyl carbamate serves as a reactive group., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)