Extending the operating range of fuel cells to higher current densities is limited by the ability of the cell to remove the water produced by the electrochemical reaction, avoiding flooding of the gas diffusion layers. It is therefore of great interest to understand the complex and dynamic mechanisms of water cluster formation in an operando fuel cell setting as this can elucidate necessary changes to the gas diffusion layer properties with the goal of minimizing the number, size, and instability of the water clusters formed. In this study, we investigate the cluster formation process using X-ray tomographic microscopy at 1 Hz frequency combined with interfacial curvature analysis and volume-of-fluid simulations to assess the pressure evolution in the water phase. This made it possible to observe the increase in capillary pressure when the advancing water front had to overcome a throat between two neighboring pores and the nuanced interactions of volume and pressure evolution during the droplet formation and its feeding path instability. A 2 kPa higher breakthrough pressure compared to static ex situ capillary pressure versus saturation evaluations was observed, which suggests a rethinking of the dynamic liquid water invasion process in polymer electrolyte fuel cell gas diffusion layers.
The emergence of multiple variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) highlights the importance of possible animal-to-human (zoonotic) and human-to-animal (zooanthroponotic) transmission and potential spread within animal species. A range of animal species have been verified for SARS-CoV-2 susceptibility, either in vitro or in vivo. However, the molecular bases of such a broad host spectrum for the SARS-CoV-2 remains elusive. Here, we structurally and genetically analysed the interaction between the spike protein, with a particular focus on receptor binding domains (RBDs), of SARS-CoV-2 and its receptor angiotensin-converting enzyme 2 (ACE2) for all conceivably susceptible groups of animals to gauge the structural bases of the SARS-CoV-2 host spectrum. We describe our findings in the context of existing animal infection-based models to provide a foundation on the possible virus persistence in animals and their implications in the future eradication of COVID-19.
The MOEMS for enviromnental applications have a complex structure architecture: a sensitive layer for environment interface, optical devices for radiation beam processing (waveguides on semiconductor) and photodiodes. The sensor includes an electronic module, used as transimpedance amplifier and phase shift detector and a radiation source coupled to the waveguide. Each of these sensor modules have specific parameters which must be optimized in order to obtain the best sensitivity for MOEMS, as well as to determine the appropriate coiicentration domain. The optimization process involves a great number of parameters and boundary conditions, so that a mathematical model is not sufficient In this paper a hardware simulator for MOEMS design and characterization is presented. The structure and dynamics of environmental signal, the beani radiation processing and the power transfer from the environmental signal to the photogenerated current are physically simulated. An application of this simulator for design and characterization of aimnoma measurement MOEMS is presented.
The ultrasonic flow-meter made by the authors, measures the frequency shifts caused by the liquid flow, using two pairs of transducers mounted in a case attached to both ends of the pipe. In the original configuration the sound waves travel between the devices that are in line with the direction of the liquid flow. The speed of the signal traveling between the transducers increases or decreases with the direction of transmission and the velocity of the liquid being measured. The phase shift of received signals, caused by frequency shift is proportional to the liquid's velocity. The signals are processed with a microcontroller included on the embedded electronics board, the results being displayed on a LCD.
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