scholarly journals Multi-functionalization of nanoporous catalytic materials to enhance reaction yield: Statistical mechanical modeling for conversion reactions with restricted diffusive transport

2014 ◽  
Vol 1641 ◽  
Author(s):  
Jing Wang ◽  
Andrés Garcia ◽  
David M. Ackerman ◽  
Mark S. Gordon ◽  
Igor I. Slowing ◽  
...  
Keyword(s):  
Reaction Diffusion ◽  
Coarse Grained ◽  
Reaction Yield ◽  
Diffusion Kinetics ◽  
Reaction Products ◽  
Dehydration Reactions ◽  
Catalytically Active ◽  
Statistical Mechanical ◽  
And Diffusion ◽  
Reaction Equilibrium

ABSTRACTMulti-functionalization of catalytically-active nanomaterials provides a valuable tool for enhancing reaction yield by shifting reaction equilibrium, and potentially also by adjusting reaction-diffusion kinetics. For example, multi-functionalization of mesoporous silica to make the interior pore surface hydrophobic can enhance yield in dehydration reactions. Detailed molecular-level modeling to describe the pore environment, as well as the reaction and diffusion kinetics is challenging, although we briefly discuss current strategies. Our focus, however, is on coarse-grained stochastic modeling of the overall catalytic process for highly restricted transport within narrow pores (with single-file diffusion), while accounting for a tunable interaction of the pore interior with reaction products. We show that making the pore interior unfavorable to products can significantly enhance yield due to both thermodynamic and kinetics factors.

scholarly journals Reaction-Diffusion Systems: Self-Balancing Diffusion and the Use of the Extent of Reaction as a Descriptor of Reaction Kinetics

2019 ◽  
Author(s):  
Miloslav Pekař
Keyword(s):  
Reaction Kinetics ◽  
Reaction Diffusion ◽  
Reaction Diffusion Systems ◽  
Diffusion Systems ◽  
And Diffusion ◽  
Reaction And Diffusion

Self-balancing diffusion is a concept which restricts the introduction of extents of reactions. This concept is analyzed in detail for mass- and molar-based balances of reaction-diffusion mixtures, in relation to non-self-balancing cases, and with respect to its practical consequences. A note on a recent generalization of the concept of reaction and diffusion extents is also included.<br>

Sulfidation of iron at high temperatures and diffusion kinetics in ferrous sulfide

1982 ◽  
Vol 17 (1-2) ◽  
pp. 77-97 ◽  
Author(s):  
M. Danielewski ◽  
S. Mrowec ◽  
A. Stołosa
Keyword(s):  
High Temperatures ◽  
Diffusion Kinetics ◽  
Ferrous Sulfide ◽  
And Diffusion

Revisiting graphene–polymer nanocomposite for enhancing anticorrosion performance: a new insight into interface chemistry and diffusion model

Nanoscale ◽  
2018 ◽  
Vol 10 (26) ◽  
pp. 12612-12624 ◽  
Author(s):  
Dipak Dutta ◽  
Andita Nataria Fitri Ganda ◽  
Jui-Kung Chih ◽  
Cheng-Chun Huang ◽  
Chung-Jen Tseng ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Polymer Nanocomposite ◽  
Diffusion Kinetics ◽  
Interfacial Chemistry ◽  
Interface Chemistry ◽  
Graphene Nanocomposite ◽  
Kinetics Of ◽  
And Diffusion ◽  
Insight Into ◽  
Percolation Network

The interfacial chemistry and diffusion kinetics of a polymer–graphene nanocomposite anticorrosion coating were studied to minimize galvanic corrosion facilitated by the formation of an interconnected graphene percolation network.

The Chemical Basis of Morphogenesis (1952)

2004 ◽  
Author(s):  
Alan Turing
Keyword(s):  
Reaction System ◽  
Reaction Diffusion ◽  
Two Dimensions ◽  
Stationary Waves ◽  
Chemical Substances ◽  
Reaction Diffusion Systems ◽  
Diffusion Systems ◽  
Random Disturbances ◽  
Physical Laws ◽  
And Diffusion

It is suggested that a system of chemical substances, called morphogens, reacting together and diffusing through a tissue, is adequate to account for the main phenomena of morphogenesis. Such a system, although it may originally be quite homogenous, may later develop a pattern or structure due to an instability of the homogeneous equilibrium, which is triggered off by random disturbances. Such reaction-diffusion systems are considered in some detail in the case of an isolated ring of cells, a mathematically convenient, though biologically unusual system. The investigation is chiefly concerned with the onset of instability. It is found that there are six essentially different forms which this may take. In the most interesting form stationary waves appear on the ring. It is suggested that this might account, for instance, for the tentacle patterns on Hydra and for whorled leaves. A system of reactions and diffusion on a sphere is also considered. Such a system appears to account for gastrulation. Another reaction system in two dimensions gives rise to patterns reminiscent of dappling. It is also suggested that stationary waves in two dimensions could account for the phenomena of phyllotaxis. The purpose of this paper is to discuss a possible mechanism by which the genes of a zygote may determine the anatomical structure of the resulting organism. The theory does not make any new hypotheses; it merely suggests that certain well-known physical laws are sufficient to account for many of the facts. The full understanding of the paper requires a good knowledge of mathematics, some biology, and some elementary chemistry. Since readers cannot be expected to be experts in all of these subjects, a number of elementary facts are explained, which can be found in text-books, but whose omission would make the paper difficult reading. In this section a mathematical model of the growing embryo will be described. This model will be a simplification and an idealization, and consequently a falsification. It is to be hoped that the features retained for discussion are those of greatest importance in the present state of knowledge. The model takes two slightly different forms. In one of them the cell theory is recognized but the cells are idealized into geometrical points.

Role of facilitated diffusion of calcium by calbindin in intestinal calcium absorption

1992 ◽  
Vol 262 (2) ◽  
pp. C517-C526 ◽  
Author(s):  
J. J. Feher ◽  
C. S. Fullmer ◽  
R. H. Wasserman
Keyword(s):  
Negative Feedback ◽  
Calcium Absorption ◽  
Feedback Inhibition ◽  
Basolateral Membrane ◽  
Reaction Diffusion ◽  
Diffusion Problem ◽  
Facilitated Diffusion ◽  
Calbindin D9k ◽  
And Diffusion

Computer simulations of transcellular Ca2+ transport in enterocytes were carried out using the simulation program SPICE. The program incorporated a negative-feedback entry of Ca2+ at the brush-border membrane that was characterized by an inhibitor constant of 0.5 microM cytosolic Ca2+ concentration ([Ca2+]). The basolateral Ca(2+)-ATPase was simulated by a four-step mechanism that resulted in Michaelis-Menten kinetics with a Michaelis constant of 0.24 microM [Ca2+]. The cytosolic diffusion of Ca2+ was simulated by dividing the cytosol into 10 slabs of equal width. Ca2+ binding to calbindin-D9K was simulated in each slab, and diffusion of free Ca2+, free calbindin, and Ca(2+)-laden calbindin was simulated between each slab. The cytosolic [Ca2+] of the simulated cells was regulated within the physiological range. Calbindin-D9K reduced the cytosolic [Ca2+] gradient, increased Ca2+ entry into the cell by removing the negative-feedback inhibition of Ca2+ entry, increased cytosolic Ca2+ flow, and increased the efflux of Ca2+ across the basolateral membrane by increasing the free [Ca2+] immediately adjacent to the pump. The enhancement of transcellular Ca2+ transport was nearly linearly dependent on calbindin-D9K concentration. The values of the dissociation constant (Kd) for calbindin-D9K were previously obtained experimentally in the presence and absence of KCl. Calbindin with the Kd obtained in the presence of KCl enhanced the simulated Ca2+ transport more than with the Kd obtained in the absence of KCl. This result suggests that the physiological Kd of calbindin is optimal for the enhancement of transcellular Ca2+ transport. The simulated Ca2+ flow was less than that predicted from the "near-equilibrium" analytic solution of the reaction-diffusion problem.

scholarly journals Non-Arrhenius Reaction-Diffusion Kinetics for Protein Inactivation over a Large Temperature Range

ACS Nano ◽  
2019 ◽  
Vol 13 (8) ◽  
pp. 8669-8679 ◽  
Author(s):  
Daipayan Sarkar ◽  
Peiyuan Kang ◽  
Steven O. Nielsen ◽  
Zhenpeng Qin
Keyword(s):  
Reaction Diffusion ◽  
Large Temperature ◽  
Diffusion Kinetics ◽  
Temperature Range ◽  
Protein Inactivation
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