Calix[4]trap: A Bioinspired Host Equipped with Dual Selection Mechanisms.

Regulation of recognition events evolving in time and space is vital for living organisms. During evolution, organisms have developed distinct and orthogonal mechanisms to achieve selective recognition, avoiding mutual interference. Although the merging of multiple selection mechanisms into a single artificial host may lead to a more adaptable recognition system with unparalleled selectivity, successful implementation of this strategy is rare. Inspired by the intriguing structures and recognition properties of two well-known biological ion binders-valinomycin and K+ channels-we herein report a series of hosts equipped with dual guest selection mechanisms. These hosts simultaneously possess a preorganized binding cavity and a confined ion translocation tunnel, which are crucial to the record-setting K+/Na+ selectivity and versatile capabilities to discriminate against a wide range of ion pairs, such as K+/Rb+, K+/Ba2+, and Rb+/Cs+. Mechanistic studies verify that the host's portal is capable of discriminating cations by their size, enabling varied ion uptake rates. The confined tunnel bearing consecutive binding sites promotes complete desolvation of ions during their inclusion into the buried cavity, mimicking the ion translocation within ion channels. Our results demonstrate that the capability to manipulate guest recognition both in equilibrium and out-of-equilibrium states allows the host to effectively discriminate diverse guests via distinct mechanisms. The strategy to merge orthogonal selection mechanisms paves a new avenue to creating more robust hosts that may function in complex biological environments where many recognition events occur concurrently.

Dispersive 2D Triptycene-Based Crystalline Polymers: Influence of Regioisomerism on Crystallinity and Morphology.

The merging of good crystallinity and high dispersibility into two-dimensional (2D) layered crystalline polymers (CPs) still represents a challenge because a high crystallinity is often accompanied by intimate interlayer interactions that are detrimental to the material processibility. We herein report a strategy to address this dilemma using rationally designed three-dimensional (3D) monomers and regioisomerism-based morphology control. The as-synthesized CPs possess layered 2D structures, where the assembly of layers is stabilized by relatively weak van der Waals interactions between C-H bonds other than the usual π-π stackings. The morphology and dispersibility of the CPs are finely tuned via regioisomerism. These findings shed light on how to modulate the crystallinity, morphology, and ultimate function of crystalline polymers using the spatial arrangements of linking groups.

Chinese Expert Consensus on Protection for Ultrasound Healthcare Workers against COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused a worldwide pandemic and poses a serious public health risk. It has been proven that lung ultrasound can be extremely valuable in the diagnosis and treatment of the disease, which could also minimize the number of exposed healthcare workers and equipment. Because healthcare workers in ultrasound departments are in close contact with patients who might be infected or virus carriers, it is extremely important that they be provided sufficient protection. Extremely aggressive protection should be avoided because it might lead to a lack of protection equipment for the hospital. Guidance on proper protection management should be provided in detail, for example, how to choose personal protective equipment, how to disinfect the environment. To address these problems, on behalf of the Chinese Ultrasound Doctors Association, Chinese PLA Professional Committee of Ultrasound in Medicine, Beijing Institute of Ultrasound in Medicine and Chinese Research Hospital Association Ultrasound Professional Committee, the authors have summarized the recommendations for effective protection according to existing hygienic standards, their experience and available literature. After the recommendations were completed, two online conferences were held on January 31, 2020 and February 7, 2020, at which the recommendations were discussed in detail. A modified version of the work was circulated and finally approved by all authors, and is the present Chinese Expert Consensus on Protection for Ultrasound Healthcare Workers against COVID-19.