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81.
Gravity driven instabilities in model porous packings of 1 mm diameter spheres are studied by comparing the broadening of the displacement front between fluids of slightly different densities in stable and unstable configurations. Water, water–glycerol and water–polymer solutions are used to vary independently viscosity and molecular diffusion and study the influence of shear-thinning properties. Both injected and displaced solutions are identical but for a different concentration of NaNO3 salt used as an ionic tracer and to introduce the density contrast. Dispersivity in stable configuration increases with polymer concentration – as already reported for double porosity packings of porous grains. Gravity-induced instabilities are shown to develop below a same threshold Péclet number Pe for water and water–glycerol solutions of different viscosities and result in considerable increases of the dispersivity. Measured threshold Pe values decrease markedly on the contrary with polymer concentration. The quantitative analysis demonstrates that the development of the instabilities is controlled by viscosity through a characteristic gravity number G (ratio between hydrostatic and viscous pressure gradients). A single threshold value of G accounts for results obtained on Newtonian and non-Newtonian solutions. 相似文献
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Francesca Bonvicini Alessandra Locatelli Rita Morigi Alberto Leoni Giovanna Angela Gentilomi 《Molecules (Basel, Switzerland)》2022,27(18)
Isatin and its derivatives are important heterocycles found in nature and present in numerous bioactive compounds which possess various biological activities. Moreover, it is an essential building block in organic synthesis. The discovery of novel compounds active against human pathogenic bacteria and fungi is an urgent need, and the isatin may represent the suitable scaffold in the design of biologically relevant antimicrobials. A small library of 18 isatin hybrids was synthetized and evaluated for their antimicrobial potential on three reference strains: S. aureus, E. coli, both important human pathogens infamous for causing community- and hospital-acquired severe systemic infections; and C. albicans, responsible for devastating invasive infections, mainly in immunocompromised individuals. The study highlighted two lead compounds, 6k and 6m, endowed with inhibitory activity against S. aureus at very low concentrations (39.12 and 24.83 µg/mL, respectively). 相似文献
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Decacationic metallostars have been prepared by the reaction of permercurated ferrocene FeC10(HgO2CCF3)10 with superacidic (C5F5NH)(SbF6) (pKa = −11 estimated in H2O) in multigram scale. In the resulting compound, [FeC10Hg10(NC5F5)n][SbF6]10, the labile pentafluoropyridine ligands are readily displaced by acetonitrile (MeCN) or tetrahydrothiophene (THT). In the X-ray structure of [FeC10Hg10(THT)10][SbF6]10·24 MeCN no cation–anion contacts between mercury and fluorine were observed. Moreover, cyclic voltammetry measurements of [FeC10(Hg(MeCN))10]10+ and [FeC10(Hg(THT))10]10+ revealed a (quasi)reversible one-electron oxidation of Fe(ii) to Fe(iii). From the reaction of [FeC10(Hg(MeCN))10]10+ with MoF6 as oxidant the ferrocenium cation [FeC10(Hg(MeCN))10]11+ was obtained and characterized via single crystal XRD. These electrophilic metallostars are promising potential building blocks for the synthesis of dendritic architectures containing a robust, tenfold functionalized ferrocene core.We present the structures of unprecedented decacationic derivatives of permercurated ferrocene that can chemically be oxidized to undecacationic ferrocenium species. 相似文献
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Rita Morigi Elena Catanzaro Alessandra Locatelli Cinzia Calcabrini Valentina Pellicioni Alberto Leoni Carmela Fimognari 《Molecules (Basel, Switzerland)》2021,26(20)
A series of new Knoevenagel adducts, bearing two indolinone systems, has been synthesized and evaluated on 60 human cancer cell lines according to protocols available at the National Cancer Institute (Bethesda, MD, USA). Some derivatives proved to be potent antiproliferative agents, showing GI50 values in the submicromolar range. Compound 5b emerged as the most active and was further studied in Jurkat cells in order to determine the effects on cell-cycle phases and the kind of cell death induced. Finally, oxidative stress and DNA damage induced by compound 5b were also analyzed. 相似文献
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Luca Leoni Dr. Rakesh Puttreddy Dr. Ondřej Jurček Andrea Mele Dr. Ilaria Giannicchi Dr. Francesco Yafteh Mihan Prof. Kari Rissanen Prof. Antonella Dalla Cort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18714-18717
The enhancement of the binding between halide anions and a Lewis acidic uranyl–salophen receptor has been achieved by the introduction of pendant electron‐deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion–π interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding. 相似文献