scholarly journals Identifying the dominant transport mechanism in single nanoscale pores and 3D nanoporous media

Author(s):  
Ying Yin ◽  
Zhiguo Qu ◽  
Maša Prodanović ◽  
Christopher J. Landry
Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.


Author(s):  
Shou-kong Fan

Transmission and analytical electron microscopic studies of scale microstructures and microscopic marker experiments have been carried out in order to determine the transport mechanism in the oxidation of Ni-Al alloy. According to the classical theory, the oxidation of nickel takes place by transport of Ni cations across the scale forming new oxide at the scale/gas interface. Any markers deposited on the Ni surface are expected to remain at the scale/metal interface after oxidation. This investigation using TEM transverse section techniques and deposited microscopic markers shows a different result,which indicates that a considerable amount of oxygen was transported inward. This is the first time that such fine-scale markers have been coupled with high resolution characterization instruments such as TEM/STEM to provide detailed information about evolution of oxide scale microstructure.


1998 ◽  
Vol 13 (11) ◽  
pp. 3282-3285 ◽  
Author(s):  
Z. Chen ◽  
F. Jiang ◽  
J.C.M. Li

Author(s):  
Balaji Selvam ◽  
Ya-Chi Yu ◽  
Liqing Chen ◽  
Diwakar Shukla

<p>The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.</p>


2018 ◽  
Vol 41 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Felipe Vázquez-Flota ◽  
Jorge Rubio-Piña ◽  
Jorge Xool-Tamayo ◽  
Mariela Vergara-Olivares ◽  
Yahaira Tamayo-Ordoñez ◽  
...  

The distribution of berberine and sanguinarine was analyzed in roots, stems and leaves of mature Argemone mexicana plants, along with that of transcripts corresponding to selected genes involved in both early biosynthetic reactions, which are common to both alkaloids, and in the late specific reactions conducting to the formation of each of them. Roots were the main sites of alkaloid accumulation, though they showed the lowest accumulation of the analyzed transcripts. Results are discussed in terms of the operation of a possible transport mechanism of alkaloids between the aerial tissues and the roots, or the occurrence of different biosynthetic alternative reactions in both parts, aerial and underground tissues, involving different gene products, yet with similar catalytic capacities.


2021 ◽  
Author(s):  
Hongyao Zhou ◽  
Haodong Liu ◽  
Xing Xing ◽  
Zijun Wang ◽  
Sicen Yu ◽  
...  

Protective Polymer Coatings (PPCs) protect lithium metal anodes in rechargeable batteries to stabilize the Li/electrolyte interface and to extend the cycle life by reducing parasitic reactions and improving the lithium deposition morphology.


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