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Controlling ion transport in nanofluidics is fundamental to water purification, bio-sensing, energy storage, energy conversion, and numerous other applications. For any of these, it is essential to design nanofluidic channels that are stable in the liquid phase and enable specific ions to pass. A human neuron is one such system, where electrical signals are transmitted by cation transport for high-speed communication related to neuromorphic computing. Here, we present a concept of neuro-inspired energy harvesting that uses confined van der Waals crystal and demonstrate a method to maximise the ion diffusion flux to generate an electromotive force. The confined nanochannel is robust in liquids as in neuron cells, enabling steady-state ion diffusion for hundred of hours and exhibiting ion selectivity of 95.8%, energy conversion efficiency of 41.4%, and power density of 5.26 W/m2. This fundamental understanding and rational design strategy can enable previously unrealisable applications of passive-type large-scale power generation., Controlling ion transport in nanofluidics is fundamental to numerous material applications but designing a material for ion selection is challenging. Here the authors report a confined van der Waals graphene oxide membrane as cation selective channel for energy generation inspired by neuron electromotive force.

Understanding the frictional properties of phosphorene is essential for reliable fabrication and sustainable operation of phosphorene-based nanotechnology devices. Although recent studies have revealed that phosphorene exhibits anisotropic frictional characteristics, the detailed mechanisms are not well analyzed, and the influence of some experimental parameters (e.g., spring stiffness, tip load force, and tip size), which are very sensitive to atomic frictional forces, were not considered. This study was carried out to address the above shortcomings. The anisotropic frictional behavior of phosphorene and its detailed mechanism were analyzed using potential energy profiles. Also, the effects of spring stiffness and tip load force on the stick-slip behaviors were investigated. Furthermore, we studied the sub-nanoscale stick-slip behavior during the nanoscale slip motion. The nanoscale and sub-nanoscale stick-slip phenomena were originated from the tip's behavior of passing over the bond between the phosphorus atoms and over the puckered honeycomb structure along the zigzag and armchair directions. We utilized a simple one-dimensional model to explain the energy profiles. The influence of tip size on the stick-slip behavior was also examined and found related to the initial nanoscale slip velocity. As the tip diameter decreased, a high-frequency sub-nanoscale stick-slip phenomenon and shorter nanoscale slip duration were identified.

Graphical abstract, Highlights: • Different binding strength and unbinding mechanism for each complex are identified. • The spA ligand is found to be tightly bound with IgG Fc portion than spG ligand. • Peculiar unbinding mechanisms are correlated to their protein secondary structures. • Various non-covalent interactions are analyzed to understand the phenomena. • The presence and role of key amino acids on each ligand are identified., In the wide array of physiological processes, protein–protein interactions and their binding are the most basal activities for achieving adequate biological metabolism. Among the studies on binding proteins, the examination of interactions between immunoglobulin G (IgG) and natural immunoglobulin-binding ligands, such as staphylococcal protein A (spA) and streptococcal protein G (spG), is essential in the development of pharmaceutical science, biotechnology, and affinity chromatography. The widespread utilization of IgG-spA/spG binding characteristics has allowed researchers to investigate these molecular interactions. However, the detailed binding strength of each ligand and the corresponding binding mechanisms have yet to be fully investigated. In this study, the authors analyzed the binding strengths of IgG–spA and IgG–spG complexes and identified the mechanisms enabling these bindings using molecular dynamics simulation, steered molecular dynamics, and advanced Poisson–Boltzmann Solver simulations. Based on the presented data, the binding strength of the spA ligand was found to significantly exceed that of the spG ligand. To find out which non-covalent interactions or amino acid sites have a dominant role in the tight binding of these ligands, further detailed analyses of electrostatic interactions, hydrophobic bonding, and binding free energies have been performed. In investigating their binding affinity, a relatively independent and different unbinding mechanism was found in each ligand. These distinctly different mechanisms were observed to be highly correlated to the protein secondary and tertiary structures of spA and spG ligands, as explicated from the perspective of hydrogen bonding.

Wetting Na metal on the solid electrolyte of a liquid Na battery determines the operating temperature and performance of the battery. At low temperatures below 200 °C, liquid Na wets poorly on a solid electrolyte near its melting temperature (Tm = 98 °C), limiting its suitability for use in low-temperature batteries used for large-scale energy-storage systems. Herein, we propose the use of sparked reduced graphene oxide (rGO) that can improve the Na wetting in sodium-beta alumina batteries (NBBs), allowing operation at lower temperatures. Experimental and computational studies indicated rGO layers with nanogaps exhibited complete liquid Na wetting regardless of the surface energy between the liquid Na and the graphene oxide, which originated from the capillary force in the gap. Employing sparked rGO significantly enhanced the cell performance at 175 °C; the cell retained almost 100% Coulombic efficiency after the initial cycle, which is a substantial improvement over cells without sparked rGO. These resul...

Stacked graphene-oxide (GO) membranes have been reported to have promising potential for desalination. One key issue in the development of such membranes is understanding the atomistic water-permeation mechanism determined by the highly variable nature of GO (including membrane morphology, surface chemistry, osmotic pressure, and surface area). To clearly understand this variability, not only individual but also synergistic effects, i.e., the nonlinear cumulative effects of membrane properties, should be investigated. Hence, this paper explores how lateral and vertical permeation mechanisms differ with changes in the morphology and surface chemistry, either discretely or simultaneously, using both experiments and simulations. Experiments reveal that the GO water-permeation performance is dominated by the heterogeneous structural and chemical nature of GO. To investigate individual and synergistic effects on water dynamics, we performed molecular-dynamics simulations. The synergistic effects were more marked on the lateral permeation mechanisms than on the vertical mechanism in GO membranes. When the membrane nanochannels had a narrow intersheet distance or no gap overlap, the lateral permeation mechanism was found to be completely different owing to the interplay between these properties.

In order to obtain uniform thickness of a blu-ray disc cover layer, a CFD analysis and an experimental comparison of the cover layer thickness distribution during the spin-coating process were conducted. The blu-ray disc, a next generation optical disc format having 25GB capacity over, consists of a thermoplastic polymer substrate layer which has a thickness of 1.1mm, a sputtered reflective metal layer and UV polymer cover layer which has a thickness of 100μm. Especially, the cover layer, which primarily governs the optical quality of the disc, is made by a precise spin coating process. However, it is still hard to get a satisfactory coating uniformity, typically, the thickness variation of the cover layer should be maintained under ±3μm, because of the unavoidable bump formed around the rim of the disc. In order to improve the dimensional accuracy of the cover layer, first, through the CFD analyses of spin coating process, the optimal spin coating conditions were obtained; and second, the edge of the disc substrate was modified into various shapes, such as chamfer, round, step, the height of the bump can be kept under the desired accuracy.