Dominating electron-electron scattering enables viscous electron flow exhibiting hydrodynamic current density patterns, such as Poiseuille profiles or vortices. The viscous regime has recently been observed in graphene by nonlocal transport experiments and mapping of the Poiseuille profile. Herein, we probe the current-induced surface potential maps of graphene field-effect transistors with moderate mobility using scanning probe microscopy at room temperature. We discover micrometer-sized large areas appearing close to charge neutrality that show current-induced electric fields opposing the externally applied field. By estimating the local scattering lengths from the gate dependence of local in-plane electric fields, we find that electron-electron scattering dominates in these areas as expected for viscous flow. Moreover, we suppress the inverted fields by artificially decreasing the electron-disorder scattering length via mild ion bombardment. These results imply that viscous electron flow is omnipresent in graphene devices, even at moderate mobility.
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http://dx.doi.org/10.1021/acs.nanolett.1c01145 | DOI Listing |
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January 2025
Leicester Institute for Pharmaceutical Innovation, Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester, LE1 9BH, UK.
Guiding molecular assembly of peptides into rationally engineered nanostructures remains a major hurdle against the development of functional peptide-based nanomaterials. Various non-covalent interactions come into play to drive the formation and stabilization of these assemblies, of which electrostatic interactions are key. Here, the atomistic mechanisms by which electrostatic interactions contribute toward controlling self-assembly and lateral association of ultrashort β-sheet forming peptides are deciphered.
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December 2024
RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
Hydrodynamics is known to emerge in electron flow when the electron-electron interaction dominates over the other momentum-nonconserving scatterings. The hydrodynamic equation that describes the electric current includes viscosity, extending beyond the Ohmic flow. The laminar flow of such a viscous electron fluid in a sample with finite width is referred to as the Poiseuille flow, where the flow velocity is maximum at the center and decreases towards the edges of the sample.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
March 2025
Tianjin Key Laboratory for Photoelectric Materials and Devices, and Key Laboratory of Display Materials & Photoelectric Devices, Ministry of Education, School of Materials Science & Engineering, Tianjin University of Technology, Tianjin 300384, China. Electronic address:
Ferroptosis, an iron-dependent programmed cell death mechanism, is mediated by distinct molecular pathways of lipid peroxidation caused by intracellular iron supplementation and glutathione synthesis inhibition that cause oxidative damage to the cell membrane. Monitoring viscosity changes of mitochondria is essential for a deeper understanding of ferroptosis, as mitochondria will be shrunk with increased membrane density and leading to drastic mitochondrial viscous changes during ferroptosis process. Thus, it is essential to explore novel and efficient fluorescent probes for monitoring viscosity in organisms.
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January 2025
Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan.
Methods Enzymol
November 2024
European XFEL, Schenefeld, Germany.
Serial femtosecond crystallography (SFX) at X-ray free electron lasers (XFELs) is a valuable technique for time-resolved structural studies on enzymes. This method allows for the collection of high-resolution datasets of protein structures at various time points during a reaction initiated by light or mixing. Experiments are performed under non-cryogenic conditions and allow the collection of radiation damage free structures.
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