Adsorption and oxidation of hydrocarbons on noble metal electrodes. VIII. Composition of adsorbed methane and rate-limiting step in the overall methane to carbon dioxide reaction

1969 ◽  
Vol 73 (7) ◽  
pp. 2397-2403 ◽  
Author(s):  
Alfred Henry Taylor ◽  
S. B. Brummer
Keyword(s):  
Carbon Dioxide ◽  
Noble Metal ◽  
Metal Electrodes ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Oxidation Of Hydrocarbons ◽  
Adsorbed Methane ◽  
Carbon Dioxide Reaction ◽  
Rate Limiting

Catalytic oxidation of n-propane and methyl alcohol over nickel(II) oxide

1981 ◽  
Vol 59 (5) ◽  
pp. 865-869 ◽  
Author(s):  
I. M. Hoodless ◽  
R. A. Ross ◽  
R. Swaminathan
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Oxidation ◽  
Water Vapour ◽  
Complete Oxidation ◽  
Oxygen Species ◽  
Fractional Rate ◽  
Rate Limiting Step ◽  
Adsorbed Oxygen Species ◽  
Limiting Step ◽  
Rate Limiting

The catalytic oxidation of propane over nickel(II) oxide has been studied in the temperature range 280 to 490 °C. Complete oxidation to carbon dioxide and water occurred. Fractional rate order dependencies were obtained for propane and oxygen and the reaction was inhibited by water vapour but not by carbon dioxide. It is suggested that the interaction of the adsorbed hydrocarbon with the adsorbed oxygen species, O−, is the rate-limiting step in the reaction at the lower temperature.Preliminary measurements of the oxidation of propane–methanol mixtures indicated that the alcohol supressed carbon dioxide formation. Conductivity studies have shown that, in these mixtures, methanol strongly interacts with the catalyst resulting in surface reduction.

scholarly journals Physiological and Transcriptomic Analyses Revealed the Implications of Abscisic Acid in Mediating the Rate-Limiting Step for Photosynthetic Carbon Dioxide Utilisation in Response to Vapour Pressure Deficit in Solanum Lycopersicum (Tomato)

2021 ◽  
Vol 12 ◽  
Author(s):  
Dalong Zhang ◽  
Qingjie Du ◽  
Po Sun ◽  
Jie Lou ◽  
Xiaotian Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Vapour Pressure Deficit ◽  
Plant Water ◽  
Mesophyll Conductance ◽  
Tomato Plants ◽  
Plant Water Stress ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Photosynthetic Carbon ◽  
Rate Limiting

The atmospheric vapour pressure deficit (VPD) has been demonstrated to be a significant environmental factor inducing plant water stress and affecting plant photosynthetic productivity. Despite this, the rate-limiting step for photosynthesis under varying VPD is still unclear. In the present study, tomato plants were cultivated under two contrasting VPD levels: high VPD (3–5 kPa) and low VPD (0.5–1.5 kPa). The effect of long-term acclimation on the short-term rapid VPD response was examined across VPD ranging from 0.5 to 4.5 kPa. Quantitative photosynthetic limitation analysis across the VPD range was performed by combining gas exchange and chlorophyll fluorescence. The potential role of abscisic acid (ABA) in mediating photosynthetic carbon dioxide (CO2) uptake across a series of VPD was evaluated by physiological and transcriptomic analyses. The rate-limiting step for photosynthetic CO2 utilisation varied with VPD elevation in tomato plants. Under low VPD conditions, stomatal and mesophyll conductance was sufficiently high for CO2 transport. With VPD elevation, plant water stress was gradually pronounced and triggered rapid ABA biosynthesis. The contribution of stomatal and mesophyll limitation to photosynthesis gradually increased with an increase in the VPD. Consequently, the low CO2 availability inside chloroplasts substantially constrained photosynthesis under high VPD conditions. The foliar ABA content was negatively correlated with stomatal and mesophyll conductance for CO2 diffusion. Transcriptomic and physiological analyses revealed that ABA was potentially involved in mediating water transport and photosynthetic CO2 uptake in response to VPD variation. The present study provided new insights into the underlying mechanism of photosynthetic depression under high VPD stress.

scholarly journals Double layer charging driven carbon dioxide adsorption limits the rate of electrochemical carbon dioxide reduction on Gold

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Stefan Ringe ◽  
Carlos G. Morales-Guio ◽  
Leanne D. Chen ◽  
Meredith Fields ◽  
Thomas F. Jaramillo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Mass Transport ◽  
Double Layer ◽  
Electrochemical Kinetics ◽  
Hydrogen Electrode ◽  
Multi Scale ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Fuels And Chemicals ◽  
Rate Limiting

AbstractElectrochemical CO$$_{2}$$2 reduction is a potential route to the sustainable production of valuable fuels and chemicals. Here, we perform CO$$_{2}$$2 reduction experiments on Gold at neutral to acidic pH values to elucidate the long-standing controversy surrounding the rate-limiting step. We find the CO production rate to be invariant with pH on a Standard Hydrogen Electrode scale and conclude that it is limited by the CO$$_{2}$$2 adsorption step. We present a new multi-scale modeling scheme that integrates ab initio reaction kinetics with mass transport simulations, explicitly considering the charged electric double layer. The model reproduces the experimental CO polarization curve and reveals the rate-limiting step to be *COOH to *CO at low overpotentials, CO$$_{2}$$2 adsorption at intermediate ones, and CO$$_{2}$$2 mass transport at high overpotentials. Finally, we show the Tafel slope to arise from the electrostatic interaction between the dipole of *CO$$_{2}$$2 and the interfacial field. This work highlights the importance of surface charging for electrochemical kinetics and mass transport.

Ornithine Decarboxylase Activity in Cultured Endothelial Cells Stimulated by Serum, Thrombin and Serotonin

1978 ◽  
Vol 39 (02) ◽  
pp. 496-503 ◽  
Author(s):  
P A D’Amore ◽  
H B Hechtman ◽  
D Shepro
Keyword(s):  
Endothelial Cells ◽  
Ornithine Decarboxylase ◽  
Decarboxylase Activity ◽  
Aortic Endothelial Cells ◽  
Ornithine Decarboxylase Activity ◽  
Rate Limiting Step ◽  
Bovine Aortic Endothelial Cells ◽  
Limiting Step ◽  
Rate Limiting ◽  
Serum Serotonin

SummaryOrnithine decarboxylase (ODC) activity, the rate-limiting step in the synthesis of polyamines, can be demonstrated in cultured, bovine, aortic endothelial cells (EC). Serum, serotonin and thrombin produce a rise in ODC activity. The serotonin-induced ODC activity is significantly blocked by imipramine (10-5 M) or Lilly 11 0140 (10-6M). Preincubation of EC with these blockers together almost completely depresses the 5-HT-stimulated ODC activity. These observations suggest a manner by which platelets may maintain EC structural and metabolic soundness.

Dynamics of hepatic and peripheral insulin effects suggest common rate-limiting step in vivo

Diabetes ◽  
1993 ◽  
Vol 42 (2) ◽  
pp. 296-306 ◽  
Author(s):  
D. C. Bradley ◽  
R. A. Poulin ◽  
R. N. Bergman
Keyword(s):  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting
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