Interpretation of Activation Volumes for Water Exchange Reactions Revisited: AbInitioCalculations for Al3+, Ga3+, and In3+, and New Experimental Data

1998 ◽  
Vol 120 (26) ◽  
pp. 6569-6577 ◽  
Author(s):  
Th. Kowall ◽  
P. Caravan ◽  
H. Bourgeois ◽  
L. Helm ◽  
F. P. Rotzinger ◽  
...  
Keyword(s):  
Experimental Data ◽  
Water Exchange ◽  
Exchange Reactions

Modeling of photosynthesis light curves by linear splines

2019 ◽  
pp. 20-29
Author(s):  
Alexander S. Lelekov ◽  
Rudolf P. Trenkenshu
Keyword(s):  
Experimental Data ◽  
Chlorophyll A ◽  
Skeletonema Costatum ◽  
Light Flux ◽  
Photosynthesis Rate ◽  
Light Curves ◽  
External Irradiation ◽  
Exchange Reactions ◽  
Cell Adaptation ◽  
Linear Splines

The paper presents an example of the linear splines use to describe the photosynthesis light curves for microalgae culture. The main mathematical models of the relationship between photosynthesis rate and light are listed. Based on the previously formulated basic principles of modeling microalgae photobiosynthesis, a mathematical model is proposed that describes the dependence of the assimilation number of chlorophyll a on the value of the light flux by linear splines. The advantage of the proposed approach is a clear definition of the point of change of the limiting factor. It is shown that light-limited photosynthesis rate is determined not only by external irradiation, but also by the concentration of chlorophyll a. The light-saturated rate depends on the amount of a key enzyme complex, which limits the rate of energy exchange reactions in the cell. Verification of the proposed model on the example of the diatom microalgae Skeletonema costatum was carried out. It is shown that the higher the degree of cell adaptation to high irradiation, the better the photosynthesis curve is described by linear splines. If S. costatum cells are adapted to low irradiation, deviations of experimental data from the idealized broken line are observed, which are caused by changes in the pigment composition. When the experimental data are normalized, the cell adaptation factor is reduced, all points are described by a single broken line, which indicates the universality of the proposed approach.

Simulating Radio Element Release and Water-Rock Interactions During Dissolution of Borosilicate Glass

1997 ◽  
Vol 506 ◽  
Author(s):  
A V Chambers ◽  
T G Heath ◽  
C M Linklater ◽  
A M Thompson ◽  
R M Wiggin
Keyword(s):  
Experimental Data ◽  
Borosilicate Glass ◽  
Glass Surface ◽  
Major Elements ◽  
Reaction Products ◽  
Exchange Reactions ◽  
Model Calculations ◽  
Dissolution Behaviour ◽  
Uranium Plutonium ◽  
Good Agreement

ABSTRACTA model has been developed that can simulate in some detail the chemistry of the glass dissolution process. To test the performance of the model, calculations were carried out to predict the dissolution behaviour of a commercial borosilicate glass. The model could reproduce accurately the behaviour of major elements released from the glass, although in the case of silica, ‘sorption’ at the glass surface was required in order to achieve good agreement with experimental data. Secondary reaction products sepiolite, montmorillonite, analcime and goethite were predicted to form. Further calculations were carried out to simulate the release of radioelements (caesium, strontium, uranium, plutonium) from within the dissolving glass. The precipitation of insoluble solids was the only mechanism included in the model to retain the radioelements at the glass surface. For plutonium, there was good agreement between model predictions and available experimental data. For caesium and strontium, the model underestimated the amount of retention at the glass surface and additional retention mechanisms, such as coprecipitation or ion exchange reactions involving newly-formed clay-type minerals at the glass surface must be invoked to explain experimental observation.

Enantiomer-Specific Oxygen Exchange Reactions. 2. Acid-Catalyzed Water Exchange with 1-Phenyl-1-alkanols

1994 ◽  
Vol 116 (13) ◽  
pp. 5551-5559 ◽  
Author(s):  
Margaret V. Merritt ◽  
Dina B. Anderson ◽  
Kim A. Basu ◽  
I.-Wen Chang ◽  
Hee-Joo Cheon ◽  
...  
Keyword(s):  
Water Exchange ◽  
Oxygen Exchange ◽  
Exchange Reactions ◽  
Acid Catalyzed

Theoretical study of water-exchange reactions for the divalent ions of the first transition period

1993 ◽  
Vol 97 (15) ◽  
pp. 3765-3774 ◽  
Author(s):  
Ralf Akesson ◽  
Lars G. M. Pettersson ◽  
Magnus Sandstroem ◽  
Per E. M. Siegbahn ◽  
Ulf Wahlgren
Keyword(s):  
Water Exchange ◽  
Theoretical Study ◽  
Transition Period ◽  
Exchange Reactions ◽  
Divalent Ions
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