2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 ...carbon‐conjugated porphyrin‐based covalent organic framework (Por‐sp2c‐COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light‐emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π‐conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 −C=C− double bonds linkage ensures the stability of Por‐sp2c‐COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por‐sp2c‐COF is pivotal for cooperative photocatalysis with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.
Red, Go! An effective protocol for the selective oxidation of amines into imines was unveiled by cooperative photocatalysis of Por‐sp2c‐COF and TEMPO illuminated by 623 nm red LEDs.
Compartmentation is essential for the localization of biological processes within a cell. In 2010, three groups independently reported that cytidine triphosphate synthase (CTPS), a metabolic enzyme ...for de novo synthesis of the nucleotide CTP, is compartmentalized in cytoophidia (Greek for "cellular snakes") in bacteria, yeast, and fruit flies. Subsequent studies demonstrate that CTPS can also form filaments in human cells. Thus, the cytoophidium represents a new type of intracellular compartment that is strikingly conserved across prokaryotes and eukaryotes. Multiple lines of evidence have recently suggested that polymerization of metabolic enzymes such as CTPS and inosine monophosphate dehydrogenase into filamentous cytoophidia modulates enzymatic activity. With many more metabolic enzymes found to form the cytoophidium and its kind, compartmentation via filamentation may serve as a general mechanism for the regulation of metabolism.
The construction of 2D and 3D covalent organic frameworks (COFs) from functional moieties for desired properties has gained much attention. However, the influence of COFs dimensionality on their ...functionalities, which can further assist in COF design, has never been explored. Now, by selecting designed precursors and topology diagrams, 2D and 3D porphyrinic COFs (2D‐PdPor‐COF and 3D‐PdPor‐COF) are synthesized. By model building and Rietveld refinement of powder X‐ray diffraction, 2D‐PdPor‐COF crystallizes as 2D sheets while 3D‐PdPor‐COF adopts a five‐fold interpenetrated pts topology. Interestingly, compared with 2D‐PdPor‐COF, 3D‐PdPor‐COF showed interesting properties, including 1) higher CO2 adsorption capacity; 2) better photocatalytic performance; and 3) size‐selective photocatalysis. Based on this study, we believe that with the incorporation of functional moieties, the dimensionality of COFs can definitely influence their functionalities.
2D vs. 3D COFs: To demonstrate the influence of dimensionality on COF functionality, 2D‐PdPor‐COF and 3D‐PdPor‐COF were synthesized. The results showed that, compared to 2D‐PdPor‐COF, 3D‐PdPor‐COF not only displays higher CO2 adsorption capacity but also exhibits better photocatalytic performance and size selectivity.
Abstract We present NICER observations of the accreting X-ray pulsar 1A 0535+262 during its faint state (≲6 × 10 36 erg s −1 ), observed in several type I and type II outbursts. We discovered a ...transition of temporal and spectral properties around the luminosity L t = 3.3 × 10 35 erg s −1 , below which spectra are relatively soft and the pulse profiles have only a narrow peak. The spectra are harder and a secondary hump gradually appears in the pulse profiles when L ≳ L t . We discuss possible physical mechanisms for this transition, including different Comptonization seed photons, the disappearance of gas shocks on the neutron star surface, and the combination of plasma and vacuum polarization effects.
Patients with hypertension, diabetes, coronary heart disease, cerebrovascular illness, chronic obstructive pulmonary disease, and kidney dysfunction have worse clinical outcomes when infected with ...SARS-CoV-2, for unknown reasons. The purpose of this review is to summarize the evidence for the existence of elevated plasmin(ogen) in COVID-19 patients with these comorbid conditions. Plasmin, and other proteases, may cleave a newly inserted furin site in the S protein of SARS-CoV-2, extracellularly, which increases its infectivity and virulence. Hyperfibrinolysis associated with plasmin leads to elevated D-dimer in severe patients. The plasmin(ogen) system may prove a promising therapeutic target for combating COVID-19.
Influenza A virus (IAV), a highly infectious respiratory pathogen, has continued to be a significant threat to global public health. To complete their life cycle, influenza viruses have evolved ...multiple strategies to interact with a host. A large number of studies have revealed that the evolution of influenza A virus is mainly mediated through the mutation of the virus itself and the re-assortment of viral genomes derived from various strains. The evolution of influenza A virus through these mechanisms causes worldwide annual epidemics and occasional pandemics. Importantly, influenza A virus can evolve from an animal infected pathogen to a human infected pathogen. The highly pathogenic influenza virus has resulted in stupendous economic losses due to its morbidity and mortality both in human and animals. Influenza viruses fall into a category of viruses that can cause zoonotic infection with stable adaptation to human, leading to sustained horizontal transmission. The rapid mutations of influenza A virus result in the loss of vaccine optimal efficacy, and challenge the complete eradication of the virus. In this review, we highlight the current understanding of influenza A virus evolution caused by the mutation and re-assortment of viral genomes. In addition, we discuss the specific mechanisms by which the virus evolves.
Dinuclear gold catalysis Wang, Wenliang; Ji, Cheng-Long; Liu, Kai ...
Chemical Society reviews,
02/2021, Letnik:
5, Številka:
3
Journal Article
Recenzirano
Gold chemistry has developed extensively in the past decade, and a dozen good reviews have been presented discussing this progress. Few however have paid close attention to the progress in organic ...synthesis of dinuclear gold-catalysis. A dinuclear gold catalyst is defined here as a gold complex with two gold centers linked by a bidentate ligand. With theoretical analysis and some representative studies in recent years, this comprehensive review highlights the particular properties of dinuclear gold-complexes, especially aurophilic interactions, and systematically summarizes the recent achievements of dinuclear gold-catalyzed coupling reactions, asymmetric catalysis, and photocatalysis, where dinuclear gold catalysts tend to show a greater advantage than the mononuclear gold catalysts.
This review summarizes the recent achievements of dinuclear gold-catalyzed redox coupling, asymmetric catalysis and photocatalysis. The dinuclear gold catalysts show a better catalytic performance than the mononuclear gold catalysts in certain cases.
Radiation‐induced lung injury (RILI) is a common complication in radiotherapy of thoracic tumors and limits the therapeutic dose of radiation that can be given to effectively control tumors. RILI ...develops through a complex pathological process, resulting in induction and activation of various cytokines, infiltration by inflammatory cells, cytokine‐induced activation of fibroblasts, and subsequent tissue remodeling by activated fibroblasts, ultimately leading to impaired lung function and respiratory failure. Increasing evidence shows that mesenchymal stem cells (MSCs) may play a main role in modulating inflammation and immune responses, promoting survival and repair of damaged resident cells and enhancing regeneration of damaged tissue through soluble paracrine factors and therapeutic extracellular vesicles. Therefore, the use of the MSC‐derived secretome and exosomes holds promising potential for RILI therapy. Here, we review recent progress on the potential mechanisms of MSC therapy for RILI, with an emphasis on soluble paracrine factors of MSCs. Hypotheses on how MSC derived exosomes or MSC‐released exosomal miRNAs could attenuate RILI are also proposed. Problems and translational challenges of the therapies based on the MSC‐derived secretome and exosomes are further summarized and underline the need for caution on rapid clinical translation. Stem Cells Translational Medicine 2019;8:344–354
Mesenchymal stem cells regulate inflammatory signaling, fibrotic response, and immune cells to attenuate RILI in injured lung tissue environment via secreting an array of soluble factors.
Cancer stem cells （CSCs） have been identified as rare cell populations in many cancers, including leukemia and solid tumors. Accumulating evidence has suggested that CSCs are capable of self-renewal ...and differentiation into various types of cancer cells. Aberrant regulation of gene expression and some signaling pathways has been observed in CSCs compared to other tumor cells. CSCs are thought to be responsible for cancer initiation, progression, metastasis, recurrence and drug resistance. The CSC hypothesis has recently attracted much attention due to the potential for discovery and development of CSC-related therapies and the identification of key molecules involved in controlling the unique properties of CSC populations. Over the past several years, a tremendous amount of effort has been invested in the development of new drugs, such as nanomedicines, that can take advantage of the ＂Achilles＇ heel＂ of CSCs by targeting cell-surface molecular markers or various signaling pathways. Novel compounds and therapeutic strategies that selectively target CSCs have been identified, some of which have been evaluated in preclinical and clinical studies. In this article, we review new findings related to the investigation of the CSC hypothesis, and discuss the crucial pathways involved in regulating the development of CSC populations and the advances in studies of drug resistance. In addition, we review new CSC-targeted therapeutic strategies aiming to eradicate malignancies.
With the extensive use of two‐photon fluorescence microscopy in the biology field, the need for developing fluorescent probes with preferred two‐photon absorption (TPA) properties has attracted great ...interest. Nitric oxide (NO) is a ubiquitous signaling molecule in a variety of physiological and pathological process in living organisms. A two‐photon (TP) probe, that is, 2‐acetyl‐6‐dialkylaminonaphthalene as the reporter and an o‐diaminobenzene as the reaction site for NO, linked by prolinamide (ANO1) has been synthesized. Based on the experimental study, five other TP probes have been theoretically designed by substituting the naphthalene fluorophore with luciferin, pyrene (substitution at 1,6‐position and 2,7‐position), fluorene, and boron‐dipyrromethene units. DFT/TDDFT studies have been conducted one‐photon absorption and emission properties as well as TPA. Our results indicated that both absorption and emission spectra of designed probes show red shifts compared with ANO1. Moreover, the fluorescence intensities are enhanced after reaction with NO. Furthermore, molecular orbitals are analyzed to interpret the photoinduced electron transfer mechanism. Notably, introducing the fluorene moiety can induce the enhancement of μ0n and Δμ0n and thus modulate TPA. Accordingly, ANO4 is thought to be a promising candidate for novel TPA NO probe.
Novel TP probes for NO detection based on photoinduced electron transfer mechanism were theoretically investigated.
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