physical mechanisms
Recently Published Documents

Safe and reliable fast charging of lithium-ion batteries is contingent upon the development of facile methods of detection and quantification of lithium plating. Among the leading candidates for online lithium plating detection is analysis of the voltage plateau observed during the rest or discharge phase ensuing a charge. In this work, an operando metric, ‘S-factor,’ is developed from electrochemical data to quantitatively analyze the severity of lithium plating over a range of charge rates and temperatures. An in-situ visualization method is employed to study the physical mechanisms and phase transitions occurring at the graphite electrode during the voltage plateau.

Abstract Time and frequency domain numerical models are developed to investigate the acoustic performance of metasurface coatings for marine applications. The coating designs are composed of periodic air-filled cavities embedded in a soft elastic medium, which is attached to a hard backing and submerged in water. Numerical results for a metamaterial coating with cylindrical cavities are favourably compared with analytical and experimental results from the literature. Frequencies associated with peak sound absorption as a function of the geometric parameters of the cavities and material properties of the host medium are predicted. Variation in the cavity dimensions that modifies the cylindrical-shaped cavities to flat disks or thin needles is modelled. Results reveal that high sound absorption occurs when either the diameter or length of the cavities is reduced. Physical mechanisms governing sound absorption for the various cavity designs are described.

The shaping of the human embryo begins with compaction, during which cells come into close contact and form a tighter structure. Assisted reproductive technology (ART) studies suggest that human embryos fail compaction primarily because of defective adhesion. Based on our current understanding of animal morphogenesis, other morphogenetic engines, such as cell contractility, could be involved in shaping the human embryo. However, the molecular, cellular and physical mechanisms driving human embryo morphogenesis remain uncharacterized. Using micropipette aspiration on human embryos donated to research, we have mapped cell surface tensions during compaction. This reveals a 4-fold increase of tension at the cell-medium interface while cell-cell contacts keep a steady tension. Comparison between human and mouse reveals qualitatively similar but quantitively different mechanical strategies, with human embryos being mechanically least efficient. Inhibition of cell contractility and cell-cell adhesion in human embryos reveal that only contractility controls the surface tension responsible for compaction. Interestingly, if both cellular processes are required for compaction, they exhibit distinct mechanical signatures when faulty. Analyzing the mechanical signature of naturally failing embryos, we find evidence that non-compacting embryos or partially compacting embryos with excluded cells have defective contractility. Together, our study reveals that an evolutionarily conserved increase in cell contractility is required to generate the forces driving the first morphogenetic movement shaping the human body.

Deep eutectic solvents (DESs) are one of the most rapidly evolving types of solvents, appearing in a broad range of applications, such as nanotechnology, electrochemistry, biomass transformation, pharmaceuticals, membrane technology, biocomposite development, modern 3D-printing, and many others. The range of their applicability continues to expand, which demands the development of new DESs with improved properties. To do so requires an understanding of the fundamental relationship between the structure and properties of DESs. Computer simulation and machine learning techniques provide a fruitful approach as they can predict and reveal physical mechanisms and readily be linked to experiments. This review is devoted to the computational research of DESs and describes technical features of DES simulations and the corresponding perspectives on various DES applications. The aim is to demonstrate the current frontiers of computational research of DESs and discuss future perspectives.

Living systems propagate by undergoing rounds of cell growth and division. Cell division is at heart a physical process that requires mechanical forces, usually exerted by assemblies of cytoskeletal polymers. Here we developed a physical model for the ESCRT-III–mediated division of archaeal cells, which despite their structural simplicity share machinery and evolutionary origins with eukaryotes. By comparing the dynamics of simulations with data collected from live cell imaging experiments, we propose that this branch of life uses a previously unidentified division mechanism. Active changes in the curvature of elastic cytoskeletal filaments can lead to filament perversions and supercoiling, to drive ring constriction and deform the overlying membrane. Abscission is then completed following filament disassembly. The model was also used to explore how different adenosine triphosphate (ATP)-driven processes that govern the way the structure of the filament is changed likely impact the robustness and symmetry of the resulting division. Comparisons between midcell constriction dynamics in simulations and experiments reveal a good agreement with the process when changes in curvature are implemented at random positions along the filament, supporting this as a possible mechanism of ESCRT-III–dependent division in this system. Beyond archaea, this study pinpoints a general mechanism of cytokinesis based on dynamic coupling between a coiling filament and the membrane.

A comparative analysis of the initial stages of degradation of ultraviolet and blue LED structures with InGaN / GaN quantum wells is carried out. In the mode of accelerated aging, the structures were subjected to short-term, sequential exposure to currents of 80–190 mA at forward bias. The exposure time did not exceed three hours. There was an increase (up to 20%) in the external quantum efficiency. The most probable physical mechanisms explaining the changes in InGaN / GaN LEDs are presented and possible ways to slow down the aging of UV LEDs are outlined.

Abstract Intrinsic roughness of solid surfaces causes a series of inevitable shortcomings in the use of mechanical electrical contacts, among which one of the most fatal is the repulsive electrodynamic force arising from high currents. A large contact force coming from a heavy holding mechanism helps to suppress the repulsive effect whereas the mechanism consumes energy and remains to be challenging for a compact switching device. Here, a liquid metal (LM) bridge is introduced to wet solid electrodes to eliminate contact issues. Four instability patterns induced by the electromagnetic pinch effect are identified to characterize LM bridge’s response to high currents. Simulation results reveal that an inner vortex caused by uneven distributions of current density and electrodynamic volume force leads to the rupture of a necked LM bridge. With a uniform structure, a cylindrical LM bridge is proved to be robust with respect to an impulse current higher than 10 kA, exceeding a commercial compact relay by a factor of more than 10 in terms of current withstand performance. Our research facilitates compact and energy-saving switch equipment and has a potential to realize arbitrary desired levels of high current withstand without the use of a holding mechanism. This paper also offers deep insights into the high current applications of LM from the perspective of fluid related physical mechanisms.