298 research outputs found

    Controllable Self-Assembly of Amphiphilic Dendrimers on a Silica Surface: The Effect of Molecular Topological Structure and Salinity

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    The adsorption kinetics and equilibrium of amphiphilic dendrimers based on poly­(amidoamine) modified with a dodecyl chain, G<i><sub>n</sub></i>QPAMC<sub>12</sub> (<i>n</i> represents the generation number), with different generation numbers at a silica–water interface have been investigated. The effect of molecular shape with different charge characteristics on the adsorption kinetics, adsorption isotherms, and the conformation of a self-assembled layer has been elucidated. For the adsorption kinetics, two steps were observed including the adsorption of individual molecules at concentrations below the critical micelle concentration (cmc) and the predominant adsorption of aggregates above the cmc. However, the adsorption isotherm, as a function of the generation number, presented an exceptional characteristic, in which a decrease in adsorption mass with different levels occurred in a high generation of amphiphilic dendrimers, depending on the balance of hydrophobic interaction and electrostatic repulsion. Atomic force microscopy imaging showed that flattened films with pores (spacing) of various shapes and roughness of 3–4 nm were formed, of which the pores (spacing) decreased obviously as the generation number increased. The addition of electrolyte (NaBr) has a great effect on the film morphology formed by the G<sub>3</sub>QPAMC<sub>12</sub> dendrimer adsorbed at the silica–water interface, showing that the film became closer with smaller pores with increased NaBr concentration

    Effects of Catalyst Type and Reaction Parameters on One-Step Acrylation of Soybean Oil

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    Unlike the conventional synthesis of acrylated soybean oil (ASO) that usually involved several steps, a novel one-step reaction synthesis of ASO was introduced in this study. ASO was prepared directly from the addition reaction of soybean oil (SO) and acrylic acid (AA). Effects of catalyst type, reaction stoichiometry, and conditions of the one-step synthesis of ASO were investigated in detail. The products were characterized using <sup>1</sup>H NMR, <sup>13</sup>C NMR, and FTIR. BF<sub>3</sub>·Et<sub>2</sub>O was found to be the most effective catalyst for this addition reaction. The results indicated that high catalyst and AA concentrations greatly increased the conversion to ASO and accelerated the reaction. Side reactions, such as polymerization of AA and transesterification between triglycerides and AA, were also noted during the reaction and were examined using <sup>1</sup>H NMR. The feasibility of recovering and reusing the catalyst and excess AA was evaluated

    Demise of mcr-1 and mcr-3.19 mediated by plasmid elimination and ISApl1

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    The sequences in the three files were assembled sequenes of plasmids found in three danghter clones with flye tool based on Nanopore MinION long-read data

    Mechanochemical Synthesis of Ketones via Chemoselective Suzuki–Miyaura Cross-Coupling of Acyl Chlorides

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    The direct synthesis of ketones via acyl Suzuki–Miyaura cross-coupling of widely available acyl chlorides is a central transformation in organic synthesis. Herein, we report the first mechanochemical solvent-free method for highly chemoselective synthesis of ketones from acyl chlorides and boronic acids. This acylation reaction is conducted in the solid state, in the absence of potentially harmful solvents, for a short reaction time and shows excellent selectivity for C­(acyl)–Cl bond cleavage

    Polymerization Induced Phase Separation in Composite Latex Particles during Seeded Emulsion Polymerization

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    Multiphase structured latex particles have been studied and produced for decades; however, the mechanism governing the polymerization induced phase separation process in such particles remains incomplete. These particles are typically produced by starting with a first, single phase polymer particle dispersion, and then a second polymer, nearly always thermodynamically phase incompatible with the first, is polymerized within those seed particles. The Gibbs free energy change upon demixing is the driving force inducing polymer–polymer phase separation during polymerization (PIPS). However, the ultimate extent of phase separation is dictated by resistances to mutual polymer chain diffusion within the latex particles. Here, we have elucidated and quantified the contributions of thermodynamic driving force and kinetic diffusive limitations to polymer–polymer phase separation within composite nanoparticles. We present a means to evaluate both the influence of chemistry and process conditions on a master plot profile predictive of a wide range of systems

    Comprehensive understanding of co-evolution and fitness cost of mcr-1 and mcr-3 in E. coli strains via long-read sequencing

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    The complete genome sequences of five E. coli strains coharboring mcr-1 and mcr-3 variants were submitted here for reference.</div

    The main interface of the virtual prediction software platform.

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    The main interface of the virtual prediction software platform.</p
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