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Brain Dynamics: Neural Systems in Space and Time
Published in Ranjit Kumar Upadhyay, Satteluri R. K. Iyengar, Spatial Dynamics and Pattern Formation in Biological Populations, 2021
Ranjit Kumar Upadhyay, Satteluri R. K. Iyengar
The electric potential and concentration gradients drive the ions across the membrane channel. Potassium ions diffuse outside the cell as the external concentration of the ions is lower than the internal concentration. If we excite the cell, potassium ions carry a positive charge and flow outside the cell and leave a negative charge inside the cell. It generates outside current flow across the membrane. The positive and negative charges separate on both sides of the cell membrane which produce an electrical potential difference across the cell membrane. It is called the membrane voltage or transmembrane potential. The potential slows down the diffusion process of potassium ions as the ions are attracted to the negatively charged molecules inside the cell and they are repelled from the positively charged ions outside the cell. The concentration and electrical potential gradients apply equal and opposite forces which balance the two forces, and equilibrium is formed where the cross-membrane current becomes zero. It is denoted by the Nernst equation (see [64]): E=(RTFz)ln[[ion]outside[ion]inside],
Response and tolerance ability of Chlorella vulgaris to cadmium pollution stress
Published in Environmental Technology, 2022
Weiwei Geng, Xinfeng Xiao, Linlin Zhang, Weiming Ni, Na Li, Yanjun Li
The combination of heavy metals that enter the cell via some migration method and macromolecular compounds in the cell may be a useful detoxification method [6]. MOE is a useful method to study the optimal binding sites of Cd with intracellular macromolecules. In this study, MOE software was used to find out the preferred binding mode and site between Cd and macromolecular compounds in cells. The selected macromolecular compounds were LCI1 membrane channel protein and plant chelatin intermediate Alr0975 protein. As shown in Figure 7, Cd can form an ionic bond with GluA58 in LCI1 membrane channel protein (Figure 7(a), and Cd can form an ionic bond with LeuB46 in Alr0975 protein (Figure 7(b)). As a kind of chemical bond, the ionic bond has strong intermolecular force. It could be seen that the large pockets of membrane channel protein and Alr0975 protein provided the entrance for Cd to enter the active site. The most reasonable complex conformations were shown in Figure 7(c,d), respectively. Therefore, the stable chemical bond between Cd and macromolecular protein may be an effective detoxification mechanism.
Optimization of module length and number of stages in a multistage membrane distillation configuration
Published in Experimental Heat Transfer, 2020
Figure 10 represents variability in the operating cost per volume of water produced with respect to variations in the membrane channel depth. The latter affects fluid velocity inside membrane channels without changing the feed flow rate. It is expected that increasing the fluid velocity will affect hydrodynamics inside the membrane and hence enhance permeate flux. It turns out that for given membrane fiber properties, the tested fluid velocity range has a marginal impact on the process performance.