No abstract

A robust two-dimensional covalent organic framework (COF-JLU5), which exhibits excellent heterogeneous photocatalytic performances for oxidative C–H functionalizations under visible-light irradiation using O2as a green oxygen source, is reported.

Two‐dimensional covalent organic frameworks (2D‐COFs) have emerged as attractive platforms for solar‐to‐chemical energy conversion. In this study, we have implemented a gradient heating strategy to synthesize a sp2‐carbon‐linked triazine‐based COF, COF‐JLU100, exhibiting high crystallinity, large surface area, good durability and carrier mobility for solar‐driven photocatalytic hydrogen evolution. The Pt‐doped COF‐JLU100 demonstrated a high hydrogen evolution rate of over 100 000 μmol g−1 h−1 for water splitting under visible‐light illumination (λ>420 nm). Experimental and theoretical studies corroborate that the cyano‐vinylene segments in COF‐JLU100 extend the π‐delocalization and enable fast charge transfer and separation rates as well as good dispersion in water. Moreover, COF‐JLU100 can be prepared by low‐cost and easily available monomers and has excellent stability, which is desirable for practical solar‐driven hydrogen production.

Two-dimensional covalent−organic frameworks (2D COFs) have recently emerged as great prospects for their applications as new photocatalytic platforms in solarto-hydrogen conversion; nevertheless, their inefficient solar energy capture and fast charge recombination hinder the improvement of photocatalytic hydrogen production performance. Herein, two photoactive three-component donor−π−acceptor (TCDA) materials were constructed using a multicomponent synthesis strategy by introducing electrondeficient triazine and electron-rich benzotrithiophene moieties into frameworks through sp 2 carbon and imine linkages, respectively. Compared with two-component COFs, the novel TCDA-COFs are more convenient in regulating the inherent photophysical properties, thereby realizing outstanding photocatalytic activity for hydrogen evolution from water. Remarkably, the first sp 2 carbon-linked TCDA-COF displays an impressive hydrogen evolution rate of 70.8 ± 1.9 mmol g −1 h −1 with excellent reusability in the presence of 1 wt % Pt under visible-light illumination (420−780 nm). Utilizing the combination of diversified spectroscopy and theoretical prediction, we show that the full π-conjugated linkage not only effectively broadens the visible-light harvesting of COFs but also enhances charge transfer and separation efficiency.

Coronavirus disease 2019 (COVID-19) can affect the haematopoietic system. Thrombocytopenia at admission was prevalent, while late-phase or delayed-phase thrombocytopenia (occurred 14 days after symptom onset) is rare. This retrospective, single-centre study screened 450 COVID-19 patients and enrolled 271 patients at the Union Hospital, Wuhan, China, from January 25 to March 9, 2020. COVID-19-associated delayed-phase thrombocytopenia occurred in 11Á8% of enrolling patients. The delayed-phase thrombocytopenia in COVID-19 is prone to develop in elderly patients or patients with low lymphocyte count on admission. The delayedphase thrombocytopenia is significantly associated with increased length of hospital stay and higher mortality rate. Delayed-phase nadir platelet counts demonstrated a significantly negative correlation with B cell percentages. We also provided and described bone marrow aspiration pathology of three patients with delayed-phase thrombocytopenia, showing impaired maturation of megakaryocytes. We speculated that immune-mediated platelet destruction might account for the delayed-phase thrombocytopenia in a group of patients. In addition, clinicians need to pay attention to the delayed-phase thrombocytopenia especially at 3-4 weeks after symptom onset.

A metal-free photocatalyst was screened from the same series of CMP materials through the bandgap engineering strategy. It exhibited excellent photocatalytic performances for the synthesis of benzimidazoles with high activity and recyclability.

Due to its fast and high resolution characteristics, dual-comb spectroscopy has attracted an increasing amount of interest since its first demonstration. In the terahertz frequency range where abundant absorption lines (finger prints) of molecules are located, multiheterodyne spectroscopy that employs the dual-comb technique shows an advantage in real-time spectral detection over the traditional Fourier transform infrared or time domain spectroscopies. Here, we demonstrate compact terahertz dual-comb spectroscopy based on quantum cascade lasers (QCLs). In our experiment, two free-running QCLs generate approximately 120 GHz wide combs centered at 4.2 THz, with slightly different repetition frequencies. We observe that ∼490 nW terahertz power coupling of one laser into the other suffices for laser-self-detecting the dual-comb spectrum that is registered by a microwave spectrum analyzer. Furthermore, we demonstrate practical terahertz transmission dual-comb spectroscopy with our device, by implementing a short air path at room temperature. Spectra are shown of semiconductor samples and of moist air, the latter allowing rapid monitoring of the relative humidity. Our devices should be readily extendable to perform imaging, microscopy and near-field microscopy in the terahertz regime. arXiv:1904.03330v5 [physics.optics]

A methoxy‐poly(ethylene glycol)‐block‐poly(acrylamide‐co‐acrylonitrile) (mPEG‐b‐P(AAm‐co‐AN)) amphiphilic copolymer exhibiting upper critical solution temperature (UCST) behavior is synthesized, and micelles from this copolymer are fabricated. It is found that the thermal responses of these micelles are tunable through balancing the hydrophobic/hydrophilic blocks in the copolymer. The size of the doxorubicin (DOX)‐loaded micelles is dependent on the hydrophobic interaction as well as hydrogen bonding between polymer and drug molecules. As a proof of concept, the drug release behavior is studied in vitro, and the cumulative release of DOX increases at temperature above the UCST of blank micelles. 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assays indicate that these polymers are non‐toxic towards human hepatic carcinoma cells (Bel 7402 cells) as well as human embryonic hepatocytes (L02 cells). DOX‐loaded micelles could effectively enter Bel 7402 cells in 2 h, and display much lower half inhibitory concentration compared with free DOX. These micelles may be exploited as a promising drug carrier for cancer therapeutics.