RECOIL-ACTIVATED AND THERMAL EXCHANGE REACTIONS BETWEEN SULFUR-35 AND CARBON DISULFIDE

1948 ◽  
Vol 70 (4) ◽  
pp. 1670-1670 ◽  
Author(s):  
Raymond R. Edwards ◽  
Frances B. Nesbett ◽  
A. K. Solomon
Keyword(s):  
Carbon Disulfide ◽  
Exchange Reactions ◽  
Thermal Exchange

scholarly journals Exchange reactions between deuterium and hydrogen halides. I. Hydrogen chloride

1939 ◽  
Vol 173 (955) ◽  
pp. 503-530 ◽  
Keyword(s):  
Hydrogen Chloride ◽  
Theoretical Calculations ◽  
Bimolecular Reaction ◽  
Activation Energies ◽  
State Theory ◽  
Thermal Method ◽  
Exchange Reactions ◽  
Elementary Reactions ◽  
Thermal Exchange ◽  
Type D

In the majority of gaseous exchange reactions, deuterium atoms, produced photochemically or by an electric discharge, have been employed to initiate the reaction. Only the thermal method offers some prospect of detecting exchange reactions of the type D 2 + HA→DA + HD. At high temperatures in addition atomic reactions will occur initiated by thermally dissociated atoms which, although present in very low concentration, react with very much smaller activation energies. Thus thermal exchange reactions can be brought about by two different mechanisms, their relative velocities being mainly dependent on the activation energies of the elementary reactions involved. Using activation energies derived from band spectroscopic data, Eyring and his collaborators attempted to predict the mechanism for several reactions where such alternative mechanisms were possible (Eyring 1931). Thus in the case of the exchange reaction of hydrogen and deuterium the method was successful in eliminating the molecular and predicting the atomic reaction, in agreement with experiment. The reaction of deuterium and hydrogen chloride offers another possibility of testing such calculations. Previous work indicated the existence of a bimolecular reaction, and it seemed, probable that at higher temperatures the atomic mechanism would intrude (Gross and Steiner 1936). It seemed desirable to investigate whether this reaction really proceeded in both ways and whether the quantitative aspects of this more complicated behaviour could be determined. The reactions have an additional interest, in that the transition state theory can be applied to calculate their rate, since they are sufficiently simple to permit us to derive the necessary data (Wheeler, Topley and Eyring 1936). Experiments were performed with deuterium and hydrogen chloride mixtures, as well as with hydrogen and deuterium chloride. In addition the ortho-para-hydrogen conversion catalysed by hydrogen chloride has been studied. The bimolecular reaction was observed, but an additional atomic chain mechanism was found to take part. The results obtained lead to a consistent mechanism from which the rates of the elementary reactions can be derived. These are then compared with the theoretical calculations.

Catalysis of thermal exchange reactions between carboxyl groups and14CO2

1989 ◽  
Vol 135 (2) ◽  
pp. 125-129
Author(s):  
J. Szammer ◽  
E. Simon-Trompler ◽  
L. Ötvös
Keyword(s):  
Carboxyl Groups ◽  
Exchange Reactions ◽  
Thermal Exchange

Exchange reactions and electrolytic dissociation

1948 ◽  
Vol 45 ◽  
pp. 147-149 ◽  
Author(s):  
C. C. Evans ◽  
S. Sugden
Keyword(s):  
Exchange Reactions ◽  
Electrolytic Dissociation

Improvement in the Fock test for determining the reactivity of dissolving pulp

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 21-26 ◽  
Author(s):  
CHAO TIAN ◽  
LINQIANG ZHENG ◽  
QINGXIAN MIAO ◽  
CHRIS NASH ◽  
CHUNYU CAO ◽  
...  
Keyword(s):  
Moisture Content ◽  
Sodium Hydroxide ◽  
Constant Temperature ◽  
Carbon Disulfide ◽  
Testing Procedure ◽  
Dissolving Pulp ◽  
Water Bath ◽  
Testing Conditions ◽  
Pulp Sample ◽  
Fock Reactivity

The Fock test is widely used for assessing the reactivity of dissolving pulp. The objective of this study was to modify the method to improve the repeatability of the test. Various parameters that affect the repeatability of the Fock test were investigated. The results showed that Fock reactivity is dependent on testing conditions affecting the xanthation between cellulose and carbon disulfide, such as the moisture content of the pulp sample, sodium hydroxide (NaOH) concentration, xanthation temperature, carbon disulfide dosage, and xanthation time. The repeatability of the test was significantly improved using the following modified testing procedure: air dried sample in the constant temperature/humidity room, xanthation temperature of 66°F (19°C) in a water bath, xanthation time of 3 h, NaOH concentration of 9% (w/w), and 1.3 mL carbon disulfide.

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.

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