To investigate geometric and electrochemical characteristics of Li ion battery electrode with different packing densities, lithium cobalt oxide (LiCoO 2 ) cathode electrodes were fabricated from a 94:3:3 (wt%) mixture of LiCoO 2 , polymeric binder, and super-P carbon black and calendered to different densities. A synchrotron X-ray nano-computed tomography system with a spatial resolution of 58.2 nm at the Advanced Photon Source of the Argonne National Laboratory was employed to obtain three dimensional morphology data of the electrodes. The morphology data were quantitatively analyzed to characterize their geometric properties, such as porosity, tortuosity, specific surface area, and pore size distribution. The geometric and electrochemical analysis reveal that high packing density electrodes have smaller average pore size and narrower pore size distribution, which improves the electrical contact between carbon-binder matrix and LiCoO 2 particles. The better contact improves the capacity and rate capability by reducing the possibility of electrically isolated LiCoO 2 particles and increasing the electrochemically active area. The results show that increase of packing density results in higher tortuosity, but electrochemically active area is more crucial to cell performance than tortuosity at up to 3.6 g/cm 3 packing density and 4 C rate.
A family of thermally regulated molybdate-based ionic liquids has been developed for highly efficient synthesis of various flavones, imines, and benzyl benzoates through one-pot oxidative cascade catalysis.
Fluorogenic
organic materials have gained tremendous attention
due to their unique properties. However, only a few of them are suitable
for bioimaging. Their different behaviors in organic and cellular
environments hinder their application in bioimaging. Thus understanding
the photoluminescent behaviors of organic materials in a cellular
context is particularly important for their rational design. Herein,
we describe two coumarin-quinazolinone conjugates: CQ and MeCQ. The high structure similarity makes them
possess similar physical and photophysical properties, including bright
fluorescence ascribed to the monomer forms in organic solvents and
aggregation-caused quenching (ACQ) effect due to self-assembly aggregation
in aqueous solution. However, they behave quite differently in cellular
context: that is, CQ exhibits bright fluorescence in
living cells, while the fluorescence of MeCQ is almost
undetectable. The different performance between CQ and MeCQ in living cells is attributed to their different scenario
in G-quadruplex (G4) DNA interaction. CQ selectively
binds with G4 DNA to recover its fluorescence via aggregation–disaggregation switching in living cells, while MeCQ remained in the aggregate form due to its poor interplay
with G4 DNA. Furthermore, CQ is applied as a two-photon
fluorescent dye, and its photoswitchable fluorescence capability is
exploited for super-resolution imaging of the specific mitochondrial
structure in living cells via the STORM technique.
A series of bis(catechol) quaternary ammonium derivatives were designed and synthesized. We investigated their ability to cross-link DNA induced by tyrosinase and found that the o-quinone is key intermediate in the process by using the nucleophile 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the tyrosinase assay. Their cytotoxicities to B16F1, Hela, and CHO cells were tested by MTT assays. The specific and potent abilities to kill the tyrosinase-efficient melanoma cells kindled our interest in exploring the relationship between their abilities of cross-linking DNA and their selective cytotoxicities to cells. Through an integrated approach including intracellular imaging for detection of the dihydroxyphenyl groups, alkaline comet assays, and γ-H2AX immunofluorescence assays, the speculation was confirmed. The bis(catechol) quaternary ammonium derivatives showed notable cell selectivity because they displayed cytotoxicities after being oxidized by tyrosinase, and they were able to target the DNA efficiently in the tyrosinase-efficient melanoma cells, forming both alkylated and cross-linked species.
Visible light mediated aerobic alternate transformations of N-alkyl isoquinolinium/quinolinium salts in the absence of extra-added photocatalysts are reported, which provides a highly concise, sustainable and low-cost protocol to unsaturated lactams...
A bisbenzimidazole was discovered to bind helix DNA, while related benzobisimidazole derivatives were found to bind and induce different G-quadruplex isomers.
A Rh-catalyzed
direct C–H amidation of 2-arylbenzo[d]thiazoles
has been developed. The transformation is characterized
by its efficiency, external oxidant-free conditions, and the avoidance
of a traditional three-step process consisting of nitration, ammoniation,
and amidation. Furthermore, several of the prepared molecules exhibit
bright white-light emission in the solid state.
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