gem-Difluoroalkene bearing a carbonyl group is a challenging target to synthesize by conventional methods. https://www.selleckchem.com/products/pik-iii.html Herein we report a mild and concise route to access the target compounds through the visible-light-mediated direct β-C-H gem-difluoroallylation of aliphatic aldehydes and cyclic ketones. Upon a synergistic combination of photoredox catalysis and organocatalysis, various α-CF3 alkenes were employed as the gem-difluoroallylation reagents via the C-F bond cleavage.Palladium-catalyzed decarbonylative alkylation reactions of acyl fluorides have been developed using alkylboranes having β-hydrogens. A wide range of functional groups were well tolerated, even at the high temperature required for decarbonylation. This protocol provides a diverse C(sp2)-C(sp3) bond formation via a highly efficient decarbonylative process. The hemilabile bidentate ligand DPPE plays a crucial role for retardation of the undesired β-hydride elimination.Grain boundaries (GBs) modulate the macroscopic properties in polycrystalline materials because they have different atomic and electronic structures from the bulk. Despite the progress on the understanding of GB atomic structures, knowledge of the localized electronic band structures is still lacking. Here, we experimentally characterized the atomic structures and the band gaps of four typical GBs in α-Al2O3 by scanning transmission electron microscopy and valence electron energy-loss spectroscopy (EELS). It was found that the band gaps of the GBs are narrowed by 0.5-2.1 eV compared with that of 8.8 eV in the bulk. By combing core-loss EELS with first-principles calculations, we elucidated that the band gap reductions directly correlate with the decrease of the coordination numbers of Al and O ions at the GBs. These results provide in-depth understanding between the local atomic and electronic band structures for GBs and demonstrate a novel electronic-structure analysis for crystalline defects.The electrical repulsion between two charged solid surfaces separated by an electrolyte is studied as a function of the permittivity ϵs of the solid in the limit in which potentials are small, and the gap between the plane solid surfaces is small compared to the Debye length κ-1 within the electrolyte. The solid surfaces are uniformly charged in a central region x0, ions spill out over much larger O(L) regions, thereby reducing still further both the electrical potential between the solid surfaces and the repulsive force between them. However, this reduction becomes smaller as κL becomes large.Exosomal microRNAs (miRNAs) are reliable and noninvasive biomarkers for the early diagnosis of cancer. Yet, accurate and feasible detection of exosomal miRNAs is often hampered by the low abundance of miRNAs in exosomes and the requirement for RNA extraction in large sample volumes. Here we show a thermophoretic sensor implemented with nanoflares for in situ detection of exosomal miRNAs, without resorting to either RNA extraction or target amplification. Thermophoretic accumulation of nanoflare-treated exosomes leads to an amplified fluorescence signal upon the binding of exosomal miRNAs to nanoflares, allowing for direct and quantitative measurement of exosomal miRNAs down to 0.36 fM in 0.5 μL serum samples. One of the best markers, exosomal miR-375, showed an accuracy of 85% for detection of estrogen receptor-positive breast cancer at early stages (stages I, II). This work provides a feasible tool to improve the diagnosis of cancer.Chagas disease is caused by the protozoan parasite Trypanosoma cruzi. It is endemic in South and Central America and recently has been found in other parts of the world, due to migration of chronically infected patients. The current treatment for Chagas disease is not satisfactory, and there is a need for new treatments. In this work, we describe the optimization of a hit compound resulting from the phenotypic screen of a library of compounds against T. cruzi. The compound series was optimized to the level where it had satisfactory pharmacokinetics to allow an efficacy study in a mouse model of Chagas disease. We were able to demonstrate efficacy in this model, although further work is required to improve the potency and selectivity of this series.Mass spectrometry and tandem MS (MS/MS) have been widely employed for the identification and quantification of damaged nucleosides in DNA, including those induced by alkylating agents. Upon collisional activation, protonated ions of alkylated nucleosides frequently undergo facile neutral loss of a 2-deoxyribose in MS/MS, and further cleavage of the resulting protonated nucleobases in MS3 can sometimes be employed for differentiating regioisomeric alkylated DNA lesions. Herein, we investigated systematically the collision-induced dissociation (CID) of the protonated ions of O4-alkylthymidine (O4-alkyldT), O2-alkyldT, O6-alkyl-2'-deoxyguanosine (O6-alkyldG), and N2-alkyldG through MS3 analysis. The MS3 of O2- and O4-MedT exhibit different fragmentation patterns from each other and from other O2- and O4-alkyldT adducts carrying larger alkyl groups. Meanwhile, elimination of alkene via a six-membered ring transition state is the dominant fragmentation pathway for O2-alkyldT, O4-alkyldT, and O6-alkyldG adducts carrying larger alkyl groups, whereas O6-MedG mainly undergoes elimination of ammonia. The breakdown of N2-alkyldG is substantially influenced by the structure of the alkyl group, where the relative ease in eliminating ammonia and alkene is modulated by the chain length and branching of the alkyl groups. We also rationalize our observations with density functional theory (DFT) calculations.We report the synthesis of two novel bridged morpholine-proline chimeras 4 and 5, which represent rigid conformationally locked three-dimensional structures wherein the lone pairs of electrons on oxygen and nitrogen are oriented in spatially different "east-west" and "north-west" directions, respectively. In combination with the presence of a carboxylic acid, the electronic features of these compounds may be useful in the context of peptidomimetic design of biologically relevant compounds. Quantitative estimates of the basicity of the nitrogen atoms were obtained using conceptual density functional theory analysis.


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Last-modified: 2025-01-23 (木) 07:02:53 (26d)