We report fabrication as well as proof-of-concept experiments of a noninvasive sensor of weak nanoscale electric fields. The sensor is a single electron transistor (SET) placed at the tip of a noncontact atomic force microscope (AFM). This is a general technology to make any nanometer-sized lithography pattern at edges or tips of a cantilever. The height control of the AFM allows the SET to hover a few nanometers above the substrate, improving both the electric field sensitivity and lateral resolution of the electrometer. Our AFM-SET sensor is prepared by a scalable technology. It means that the probe can be routinely fabricated and replaced, if broken.
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http://dx.doi.org/10.1021/nl052526t | DOI Listing |
Nat Commun
December 2024
Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Paris, France.
Replication Protein A (RPA) plays a pivotal role in DNA replication by coating and protecting exposed single-stranded DNA, and acting as a molecular hub that recruits additional replication factors. We demonstrate that archaeal RPA hosts a winged-helix domain (WH) that interacts with two key actors of the replisome: the DNA primase (PriSL) and the replicative DNA polymerase (PolD). Using an integrative structural biology approach, combining nuclear magnetic resonance, X-ray crystallography and cryo-electron microscopy, we unveil how RPA interacts with PriSL and PolD through two distinct surfaces of the WH domain: an evolutionarily conserved interface and a novel binding site.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
The CRISPR-associated endonuclease Cas9 derived from prokaryotes is used as a genome editing, which targets specific genomic loci by single guide RNAs (sgRNAs). The eukaryotes, the target of genome editing, store their genome DNA in chromatin, in which the nucleosome is a basic unit. Despite previous structural analyses focusing on Cas9 cleaving free DNA, structural insights into Cas9 targeting of DNA within nucleosomes are limited, leading to uncertainties in understanding how Cas9 operates in the eukaryotic genome.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
School of Chemistry, Xi'an Jiaotong University, Engineering Research Center of Energy Storage Materials and Devices, Ministry of Education, Xi'an 710049, China.
Herein, SUMO-LUMO inversion (SLI) radicals - were designed by the combination of the tris(2,4,6-trichlorophenyl)methyl (TTM) radical and pyridinium derivatives (electron-withdrawing groups) for the first time. The energy of the LUMO lies below that of the SUMO, which deviated from the Aufbau principle as an alternative electronic configuration beyond the well-established SOMO-HOMO inversed system. Thus, for SLI radicals, the injection of one extra electron preferred to occupy the LUMO rather than the SUMO, giving diradicals, one of which had been fully confirmed by single crystal analysis, VT-NMR and VT-EPR experiments, as well as DFT calculations.
View Article and Find Full Text PDFRev Sci Instrum
December 2024
X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
This paper presents progress made toward the overarching goal to adapt single-photon-counting microcalorimeters to magnetic fusion energy research and demonstrate the value of such measurements for fusion. Microcalorimeter spectrometers combine the best characteristics of x-ray instrumentation currently available on fusion devices: high spectral resolution similar to an x-ray crystal spectrometer and broad spectral coverage sufficient to measure impurity species from Be to W. As a proof-of-principle experiment, a NASA-built x-ray microcalorimeter spectrometer has been installed on the Madison Symmetric Torus (MST) at the Wisconsin Plasma Physics Laboratory.
View Article and Find Full Text PDFJACS Au
December 2024
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States.
Red-light absorbing photoredox catalysts offer potential advantages for large-scale reactions, expanding the range of usable substrates and facilitating bio-orthogonal applications. While many red-light absorbing/emitting fluorophores have been developed recently, functional red-light absorbing photoredox catalysts are scarce. Many photoredox catalysts rely on long-lived triplet excited states (triplets), which can efficiently engage in single electron transfer (SET) reactions with substrates.
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