Use of semigrand ensembles in chemical equilibrium calculations on complex organic systems

1989 ◽  
Vol 91 (3) ◽  
pp. 1824-1828 ◽  
Author(s):  
Robert A. Alberty ◽  
Irwin Oppenheim
Keyword(s):  
Chemical Equilibrium ◽  
Organic Systems ◽  
Complex Organic ◽  
Equilibrium Calculations

Functional Analysis and the Species Design

2017 ◽  
Author(s):  
Karen Neander
Keyword(s):  
Mental Content ◽  
Functional Explanation ◽  
Organic System ◽  
Organic Systems ◽  
Etiological Theory ◽  
Normal Human ◽  
Human Immune ◽  
Proper Functions ◽  
Complex Organic

Chapter 3 is about functional explanation in biology, rather than directly about mental content, but in this chapter the author defends a controversial premise of the methodological argument for teleosemantics (given in chapter 4). The premise is that physiologists and neurophysiologists ascribe normal-proper functions in explaining how bodies and brains operate for significant scientific reasons. How an organic system operates in the here and now depends on the actual causal contributions its components make in the here and now, and yet biologists also describe the normal-proper functions of components when explaining how (and not just why) complex organic systems operate or function the way they do. Central to the biologists’ task is describing systems that are functioning normally or properly (e.g., normal human visual systems, or normal human immune systems). The author explains how this role of a malfunction-permitting notion of function (sometimes called a “normative” notion) is consistent with the etiological theory of functions, but the aim here is not to establish the truth of the etiological theory of functions (which is defended in other works).

scholarly journals Laboratory and Modeling Studies of Chemistry in Dense Molecular Clouds

1980 ◽  
Vol 87 ◽  
pp. 331-336
Author(s):  
W.T. Huntress ◽  
S. S. Prasad ◽  
G. F. Mitchell
Keyword(s):  
Chemical Equilibrium ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Chemical Processes ◽  
Chemical Library ◽  
Interstellar Clouds ◽  
Organic Species ◽  
Radiative Association ◽  
Simple Chemical ◽  
Complex Organic

A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

scholarly journals An overview of computational methods for chemical equilibrium and kinetic calculations for geochemical and reactive transport modeling

2017 ◽  
Vol 89 (5) ◽  
pp. 597-643 ◽  
Author(s):  
Allan M. M. Leal ◽  
Dmitrii A. Kulik ◽  
William R. Smith ◽  
Martin O. Saar
Keyword(s):  
Numerical Methods ◽  
Chemical Equilibrium ◽  
Reactive Transport ◽  
Mass Action ◽  
Transport Modeling ◽  
Partial Equilibrium ◽  
Integration Scheme ◽  
Reactive Transport Modeling ◽  
Kinetic Calculations ◽  
Equilibrium Calculations

AbstractWe present an overview of novel numerical methods for chemical equilibrium and kinetic calculations for complex non-ideal multiphase systems. The methods we present for equilibrium calculations are based either on Gibbs energy minimization (GEM) calculations or on solving the system of extended law of mass-action (xLMA) equations. In both methods, no a posteriori phase stability tests, and thus no tentative addition or removal of phases during or at the end of the calculations, are necessary. All potentially stable phases are considered from the beginning of the calculation, and stability indices are immediately available at the end of the computation to determine which phases are actually stable at equilibrium. Both GEM and xLMA equilibrium methods are tailored for computationally demanding applications that require many rapid local equilibrium calculations, such as reactive transport modeling. The numerical method for chemical kinetic calculations we present supports both closed and open systems, and it considers a partial equilibrium simplification for fast reactions. The method employs an implicit integration scheme that improves stability and speed when solving the often stiff differential equations in kinetic calculations. As such, it requires compositional derivatives of the reaction rates to assemble the Jacobian matrix of the resultant implicit algebraic equations that are solved at every time step. We present a detailed procedure to calculate these derivatives, and we show how the partial equilibrium assumption affects their computation. These numerical methods have been implemented in Reaktoro (reaktoro.org), an open-source software for modeling chemically reactive systems. We finish with a discussion on the comparison of these methods with others in the literature.

Molecular mobility and transitions in complex organic systems studied by shear force microscopy

2006 ◽  
Vol 18 (4) ◽  
pp. 044009 ◽  
Author(s):  
Tomoko Gray ◽  
Jason Killgore ◽  
Jingdong Luo ◽  
Alex K Y Jen ◽  
René M Overney
Keyword(s):  
Molecular Mobility ◽  
Shear Force ◽  
Force Microscopy ◽  
Organic Systems ◽  
Shear Force Microscopy ◽  
Complex Organic

Enzymes in preparative organic synthesis. Chemical equilibrium in countercurrent biphasic water-organic systems

1989 ◽  
Vol 11 (12) ◽  
pp. 875-880 ◽  
Author(s):  
A. N. Semenov ◽  
A. P. Gachok ◽  
M. I. Titov ◽  
K. Martinek
Keyword(s):  
Organic Synthesis ◽  
Chemical Equilibrium ◽  
Organic Systems

scholarly journals Optimization of Ethanol Autothermal Reforming Process with Chemical Equilibrium Calculations

2009 ◽  
Vol 3 (3) ◽  
pp. 79-85
Author(s):  
D. Markova ◽  
K. Valters ◽  
G. Bažbauers
Keyword(s):  
Chemical Equilibrium ◽  
Autothermal Reforming ◽  
Process Efficiency ◽  
Maximum Efficiency ◽  
Hydrogen Energy ◽  
Hydrogen Yield ◽  
Process Factors ◽  
Reforming Gas ◽  
Critical Process ◽  
Equilibrium Calculations

Optimization of Ethanol Autothermal Reforming Process with Chemical Equilibrium Calculations The dependence of carbon formation, hydrogen yield and efficiency of the ethanol autothermal reforming process on critical process factors is studied in the work by using chemical equilibrium calculations with a process simulation model made in the ChemCAD environment. The studied process factors are carbon-to-steam ratio S/C, air-to-fuel ratio λ and temperature in the reactor TATR. Since the goal of the reforming process is to achieve possibly higher values of H2 concentration in the reforming gas, by operating reformer at the maximum efficiency at the same time, the optimization of the reforming process was done by using objective functions which include hydrogen yield and the amount of heat supplied to the process. As a result it was found that the maximum process efficiency, which is defined as the ratio of obtained hydrogen energy to the energy supplied to the process in the studied range of process factors is 0,61, and this value can be achieved at λ value of 0,1, S/C values of 2,5-3 and temperatures in the reactor TATR 680 - 695°C. Hydrogen yield under these conditions is 4,41-4,55 mol/molC2H5OH.

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