Prediction of the Rate Coefficient for the F+SOF3 Recombination Reaction

1990 ◽  
Vol 43 (1) ◽  
pp. 169 ◽  
Author(s):  
IG Pitt ◽  
RG Gilbert ◽  
KR Ryan
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Pressure Dependence ◽  
Variational Approach ◽  
Potential Surface ◽  
Rate Coefficient ◽  
Recombination Reaction ◽  
Pressure Limit ◽  
Association Reaction ◽  
Recombination Rate Coefficient

The pressure dependence of the rate coefficient for the recombination reaction SOF3+F → SOF4 has been calculated by utilizing an RRKM canonical variational approach with a hindered-rotor Gorin potential surface. With no adjustable parameters, the high-pressure recombination rate coefficient is predicted to be c. 1×10-10cm3s-1. It was further established that this rate coefficient is close to its high-pressure limit above c. 100 Pa. These results support the conclusions of an experimental study in which this rate coefficient was measured relative to that of the association reaction between SOF3 and O.

Pressure Effects on the Ligand-Binding Kinetics for Hemoproteins and Their Site-Directed Mutants

1996 ◽  
Author(s):  
Isao Morishima
Keyword(s):  
High Pressure ◽  
Amino Acid ◽  
Ligand Binding ◽  
Pressure Dependence ◽  
Activation Volume ◽  
Bond Formation ◽  
Binding Kinetics ◽  
Amino Acid Residues ◽  
Association Reaction ◽  
Human Myoglobin

The effects of high pressure up to 1500 bar on the recombination kinetics of oxygen and carbon monoxide (CO) binding to human hemoglobin (intact and isolated chain forms), human myoglobin (and its mutants), and cytochrome P-450 were studied by the use of millisecond and nanosecond laser photolysis. The activation volumes for the binding of CO to the R- and T-quaternary states of hemoglobin (Hbs) were determined to be –9.0 and –31.7 ml, respectively. The characteristic pressure dependence of the activation volume was observed for the R-state Hb but not for the T-state Hb. More detailed studies were made with isolated α- and β-chains of human Hb. The kinetic data were analyzed on the basis of a simple three-species model, which assumes two elementary reaction processes of bond formation and steps of ligand migration. A pressure-dependent activation volume change from negative lo positive values in the bimolecular CO association reaction was observed for both chains. This is attributed to a change of the rate-limiting step from the bond-formation step to the ligandmigration step. High-pressure ligand-binding kinetics were also examined for site-specific mutants of human myoglobin in which some amino acid residues at the heme distal sites, such as Leu 29, Lys 45, Ala 66, and Thr 67, are substituted by others. The pressure dependence of the CO binding rate for the L29 mutants was unusual: a positive value was obtained unexpectedly for overall CO binding. Corresponding to this anomaly was an unusual geometry of the iron-bound CO, which was determined by IR and NMR spectroscopies. The effects of camphor and camphor analogues as substrates on the CO-binding kinetics for P-450cam were also studied under pressure. The positive activation volumes for CO binding were obtained for substrate-free and norcamphor- and adamantane-bound P-450, whereas other substrate analogue-bound P-450 complexes exhibited the negative activation volumes. All of the present high-pressure results are discussed in relation to (1) the dynamic aspects of the protein conformation, and (2) the specific participation of amino acid residues in the heme distal site in each elementary step of the ligand-binding reaction process.

scholarly journals Calculation of the ion–ion recombination rate coefficient via a hybrid continuum-molecular dynamics approach

2020 ◽  
Vol 152 (9) ◽  
pp. 094306 ◽  
Author(s):  
Tomoya Tamadate ◽  
Hidenori Higashi ◽  
Takafumi Seto ◽  
Christopher J. Hogan
Keyword(s):  
Molecular Dynamics ◽  
Recombination Rate ◽  
Rate Coefficient ◽  
Ion Recombination ◽  
Recombination Rate Coefficient

An experimental study on the flow characteristics during the leakage of high pressure CO2 pipelines

2019 ◽  
Vol 125 ◽  
pp. 92-101 ◽  
Author(s):  
Shuaiwei Gu ◽  
Yuxing Li ◽  
Lin Teng ◽  
Cailin Wang ◽  
Qihui Hu ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Flow Characteristics ◽  
High Pressure Co2

scholarly journals An ICR Study of an Association Reaction at Low Pressure

1980 ◽  
Vol 87 ◽  
pp. 305-306
Author(s):  
M.J. Mcewan ◽  
V. G. Anicich ◽  
W.T. Huntress ◽  
P. R. Kemperer ◽  
M. T. Bowers
Keyword(s):  
Pressure Range ◽  
Rate Coefficient ◽  
Low Pressure ◽  
Second Order ◽  
Radiative Association ◽  
Association Reaction

An ICR investigation of the association reactionCH3+ + HCN CH3.HCN+has shown the reaction follows second order kinetics over the pressure range 1 × 10-6 to 3 × 10-4 Torr with a rate coefficient of 2 × 10-10 cm3s-1. These results can be interpreted in terms of a saturated 3-body or radiative association mechanism.

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

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