A numerical investigation on Glimm’s method as applied to water sloshing and impacting is carried out. Emphasis is given to the handling and predicting hydraulic jumps. The effects of the spatial and temporal discretizations are examined. Three shallow water problems, 1) dam-breaking problem, 2) water sloshing in a rolling tank, and 3) impact of breaking of a water reservoir, are studied. It is shown numerically that Glimm’s method is stable and converged solutions can be obtained. The characteristics of the hydraulic jumps are well captured by the numerical calculations. The numerical results are in good agreement with either analytical solutions or experimental data.
MicroRNAs (miRNAs) are important gene regulators that bind with target genes and repress target gene expression at the post-transcriptional level. The identification of target genes associated with miRNAs inside different cells is a major challenge in miRNA chemical biology due to the lack of functional miRNAs bearing appropriate tags. Here we report photoclickable miRNAs as appropriately pretagged miRNAs that keep the intracellular function of miRNAs and allow the addition of molecular handles through photoclick reaction. The photoclickable miRNAs upon transfection inside cells were able to form functional complexes with target genes and repress target gene expression. Target genes associated with the photoclickable miRNAs in the complexes were then tagged with the molecular handle through photoclick reaction for pull-down and identification. Using photoclickable miR-106a, miR-27, and miR-122, we first verified that their intracellular function was comparable to that of intact miRNAs, which showed obvious advantage over corresponding biotinylated miRNAs. After attaching the biotin handle to the associated complexes containing the photoclickable miRNAs through the tetrazole-ene photoclick reaction, target genes previously bound with these miRNAs inside cells were successfully pulled town and analyzed. The application of this strategy was demonstrated by the identification of several new target genes of miR-122, followed by revealing a novel regulatory pathway in HepG2 cells with regard to the role of PEG10 in miR-122-promoted cell apoptosis.
Using a short peptide precursor modified by the biaryltetrazole with intramolecular photo-click reactivity, we realized the photo-regulation of the pericellular nanofibers formed by the enzyme-instructed self-assembly on the cell membrane. Upon light irradiation, the fluorescence of nanofibers could be turned on to monitor both enzyme-instructed self-assembly and photo-induced disassembly processes. Moreover, the cell fate could be controlled through the photo-regulation.
Multi-functional supramolecular hydrogels have emerged as smart biomaterials for diverse biomedical applications. Here we report a multi-functional supramolecular hydrogel formed by the conjugate of the bioactive GRGDS peptide with biaryltetrazole that is the substrate of photo-click reaction. The hydrogel was used as a biocompatible matrix to encapsulate live cells for 3D culture. The presence of the RGD epitope in the hydrogelator enhanced the interaction of the nanofiber with integrin over-expressing cells, which resulted in the selective enhancement in the miRNA delivery into the encapsulated U87 cells. The intramolecular photo-click reaction of the biaryltetrazole moiety in the hydrogelator leads to a sensitive photo-response of the hydrogel, which allowed photo-degradation of the hydrogel for release of the encapsulated live cells for further bio-assay of the intracellular species.
An efficient and practical method has been developed for the diversity-oriented synthesis of polysubstituted 2-piperidinones via four-component reaction between substituted nitrostyrenes, aromatic aldehydes, ammonium acetate, and dialkyl malonates for the generation of a wide range of structurally interesting and pharmacologically significant compounds. It is worth mentioning that in the course of this reaction, the formation of products was highly stereoselective. Two differently stereochemical classes of polysubstituted 2-piperidinones depended on the substitutent position of aromatic aldehyde.
An efficient and direct synthesis of 2-arylideneamino-3-aryl-4H-furo[3,2-c]chromen-4-ones has been developed via four-component reaction from substituted nitrostyrenes, aromatic aldehydes, coumarins, and ammonium acetate under very mild conditions, which involves sequentially a Michael addition, an aza-nucleophilic addition, of the imine to the double bond, an intermolecular nucleophilic addition and a dehydration reaction. The resulting biologically intriguing structures could have broad applications in related biomedical-program structures.
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