Choline Chloride-Urea Deep Eutectic Solvent/Cu-Mn Iminodiacetate Coordination Polymer as an Efficient Catalytic System for Synthesis of Morita-Baylis-Hillman Adducts with Antimicrobial Activity.

This work shows the synthesis of a series of Morita-Baylis-Hillman adducts from isatin derivatives via an efficient green approach involving the use of a new catalyst system, a mixture of copper-manganese iminodiacetate 1D coordination polymer (Cu/Mn-IDA) and choline chloride-urea deep eutectic solvent (ChCl/urea 1:2). The adducts were obtained in good to excellent yields (59-97%) with shorter reaction times. The results demonstrate for the first time the synergistic catalytic effect of the combination of deep eutectic solvent and coordination polymer on the Morita-Baylis-Hillman reactions.

Delayed Fluorescence by Triplet-Triplet Annihilation from Columnar Liquid Crystal Films.

Delayed fluorescence (DF) by triplet-triplet annihilation (TTA) is observed in solutions of a benzoperylene-imidoester mesogen that shows a hexagonal columnar mesophase at room temperature in the neat state. A similar benzoperylene-imide with a slightly smaller HOMO-LUMO gap, that also is hexagonal columnar liquid crystalline at room temperature, does not show DF in solution, and mixtures of the two mesogens show no DF in solution either, because of collisional quenching of the excited triplet states on the imidoester by the imide. In contrast, DF by TTA from the imide but not from the imidoester is observed in condensed films of such mixtures, even though neat films of either single material are not displaying DF.

Global Analysis of a piecewise smooth epidemiological model of COVID-19.

Despite the huge relevance of vaccines for preventing COVID-19, physical isolation and quarantine of infected individuals are still the key strategies to fight against the COVID-19 pandemic. Based on a COVID-19 transmission epidemiological model governed by ordinary differential equations, here we propose an intermittent non-pharmacological protocol to control the fraction of infected individuals. In our approach, unlike what generically happens for numerical simulation models, we provide a global analysis of the model, giving qualitative information about every initial condition.

Author Correction: Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips.

We report on measurements of the switching current distributions on two-dimensional superconducting NbTiN strips that are 5 nm thick and 80 nm wide. We observe that the width of the switching current distributions has a non-monotonous temperature dependence, where it is constant at the lowest temperatures up to about 1.5 K, after which it increases with temperature until 2.