On the Analysis of Steady State Microwave Double Resonance Experiments: Level Degeneracies and M Dependence

1975 ◽  
Vol 53 (23) ◽  
pp. 2593-2605 ◽  
Author(s):  
R. M. Lees
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Double Resonance ◽  
Rotational Energy ◽  
Level System ◽  
First Order ◽  
Absolute Agreement ◽  
Transfer Signal ◽  
Collisional Rate ◽  
Dipolar Model

The analysis of data on collisional transfer of rotational energy obtained by the technique of steady state four-level microwave double resonance is reviewed, with emphasis on the roles of the spatial degeneracies of the levels and the M dependence of their populations. Exact expressions are given for the collisional transfer signal in a general four-level system, with the level degeneracies included rigorously, and with M dependent and M independent contributions formally separated. The possible effects of the M dependence are illustrated for several test systems of CH3OH, with the use of a simplified first-order dipolar model for the collisional rate constants. Collisional transfer signals calculated with this model for a number of CH3OH systems are in reasonable relative agreement with observed values, but in poor absolute agreement. It is suggested that the latter feature may be due to neglect of higher-order transitions in the simple dipolar model.

Investigation of Self-and Foreign Gas Collision-induced Transitions between M-resolved Rotational Levels of OCS

1982 ◽  
Vol 37 (4) ◽  
pp. 358-370 ◽  
Author(s):  
H. Mäder
Keyword(s):  
Energy Levels ◽  
Double Resonance ◽  
Rotational Energy ◽  
Level System ◽  
First Order

Abstract Four-level MW-MW double resonance experiments on rotational Stark levels j = 0, 1, 2 and 3 of OCS have been performed to investigate transfer of rotational energy by collisions of OCS with OCS, He, Ne, Ar, Kr, H2, N2, O2, and CH3F. Theoretical arguments are given for the interpretation of the experimentally determined η-values by considering Bloch-type equations of an "embedded" four-level system with ±M degeneracy of the energy levels. The results indicate significant deviations from first order dipole collisional interaction.

Collisional Transfer of Rotational Energy in Mixtures of Methanol with Ne, Ar, and D2

1975 ◽  
Vol 53 (23) ◽  
pp. 2617-2621
Author(s):  
S. S. Haque ◽  
R. M. Lees
Keyword(s):  
Steady State ◽  
Qualitative Analysis ◽  
Rate Constant ◽  
Double Resonance ◽  
Rotational Energy ◽  
Different Types ◽  
Transfer Signal

Steady state microwave double resonance experiments are reported for dilute mixtures of CH3OH in excess Ne, Ar, and D2. The results for Ne and Ar are, in general, similar to previous results for He, and those for D2 to H2, with both classes of collision partners displaying a decrease in collisional transfer signal with increasing mass of the partner. A simple qualitative analysis indicates that the ratios between the rates of different types of collision-induced transitions are quite similar for the members of a class. For He, Ne, and Ar, the rate constant for Δk = 0 transitions is of the order of 8 times that for a Δk = ±1 transition, while for H2 and D2 the ratio is about 4.

Graphical rules of steady-state reaction systems

1981 ◽  
Vol 59 (4) ◽  
pp. 737-755 ◽  
Author(s):  
Chou Kuo-Chen ◽  
Sture Forsen
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Mathematical Proof ◽  
Complex Reaction ◽  
Consecutive Reaction ◽  
Reaction Systems ◽  
First Order ◽  
Mathematical Proofs ◽  
Pseudo First Order ◽  
Manual Calculation

Four rules to deal with first-order or pseudo-first-order steady-state reaction systems are presented.By means of Rule 1, we can immediately write down the apparent rate constants of consecutive reaction systems. This rule is actually the same as the "Rule of Thumb" proposed by Gilbert, but here its mathematical proof is given.Rule 2 and Rule 3 may serve to derive the apparent rate constants of various complex reaction systems. In comparison with the general algebraic methods, these two rules can simplify laborious calculations that would otherwise be tedious and liable to errors.Rule 4 presents a new schematic method to calculate the concentrations of the reactants. The new method, in simplifying the calculation of complex problems, is extraordinarily efficacious in comparison with the existing schematic methods. For complex mechanisms which are too complicated to be treated with the general manual calculation method, the practical calculations show that we can easily write down the desired results by means of Rule 4.In addition, Rules 2, 3, and 4 include corresponding check formulae, by use of which we can avoid missing subgraphs to be counted. Their advantages will be manifested particularly in dealing with complex mechanisms.The mathematical proofs of these rules are given in the Appendices.

scholarly journals Electron-transfer steps involved in the reactivity of Hansenula anomala flavocytochrome b2 as deduced from deuterium isotope effects and simulation studies

1991 ◽  
Vol 274 (1) ◽  
pp. 207-217 ◽  
Author(s):  
C Capeillère-Blandin
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Phase I ◽  
Rate Constants ◽  
Intramolecular Electron Transfer ◽  
Simulation Studies ◽  
First Order ◽  
Flavocytochrome B2 ◽  
Hansenula Anomala ◽  
Phase Phase

The L-lactate-flavocytochrome b2-ferricyanide electron-transfer system from the yeast Hansenula anomala was investigated by rapid-reaction techniques. The kinetics of reduction of oxidized flavocytochrome b2 by L-lactate and L-[2H]lactate were biphasic both for flavin and haem prosthetic groups and at all concentrations tested. The first-order rate constants of the rapid and slow phases depended upon substrate concentrations, a saturation behaviour being exhibited. Substitution of the C alpha-H atom by 2H was found to cause appreciable changes in the rate constants for the initial reduction of flavin and haem (phase I), which were respectively about 3-fold and 2-fold less than with L-lactate. In contrast, no significant isotope effect was noted on the apparent reduction rate constants of the slow phase, phase II. Under steady-state conditions an isotope effect of 2.0 was found on the overall electron transfer from L-lactate to ferricyanide. These transient reduction results were discussed in terms of a kinetic model implying intra- and inter-protomer electron exchanges between flavin and haem b2, all of which have been experimentally described. Computer simulations indicate that the reaction scheme provides a reasonable explanation of the fast-reduction phase, phase I (in absence of acceptor). The pseudo-first-order rate constant for oxidation of reduced haem b2 in flavocytochrome b2 increased with increasing ferricyanide concentration in a hyperbolic fashion. The limiting value at infinite ferricyanide concentration, which was attributed to the intramolecular electron-transfer rate from ferroflavocytochrome b2 to the iron of ferricyanide within a complex, was 920 +/- 50 s-1 at pH 7.0 and 5 degrees C. Stopped-flow and rapid-freezing measurements showed haem b2 and flavin to be 90 and 44% oxidized respectively under steady-state conditions in presence of ferricyanide. Simulation studies were carried out to check the participation of the proposed reduction sequence in the overall catalytic reaction together with the role of reduced haem b2 (Hr) and flavin semiquinone (Fsq) as electron donors to ferricyanide. When the rate of the intramolecular electron-transfer exchange between Fsq and ferricyanide was adjusted to 200 s-1, simulated data accounted for molar activities defined under various conditions of L-lactate, [2H]lactate and ferricyanide concentrations. Simulation studies were extended to data obtained using cytochrome c as acceptor and reaction catalysed by Saccharomyces cerevisiae flavocytochrome b2. The differences in reactivity observed for Hr and Fsq with ferricyanide and cytochrome c were discussed in terms of redox potentials, electrostatic interactions, distances and accessibility of the participating groups.

scholarly journals Quantitative ER ↔ Golgi Transport Kinetics and Protein Separation upon Golgi Exit Revealed by Vesicular Integral Membrane Protein 36 Dynamics in Live Cells

2001 ◽  
Vol 12 (5) ◽  
pp. 1481-1498 ◽  
Author(s):  
Thorsten Dahm ◽  
Jamie White ◽  
Stephan Grill ◽  
Joachim Füllekrug ◽  
Ernst H.K. Stelzer
Keyword(s):  
Endoplasmic Reticulum ◽  
Steady State ◽  
Rate Constants ◽  
Protein Separation ◽  
Secretory Pathway ◽  
Fluorescent Protein ◽  
Temperature Shift ◽  
Live Cells ◽  
First Order ◽  
Order Rate

To quantitatively investigate the trafficking of the transmembrane lectin VIP36 and its relation to cargo-containing transport carriers (TCs), we analyzed a C-terminal fluorescent-protein (FP) fusion, VIP36-SP-FP. When expressed at moderate levels, VIP36-SP-FP localized to the endoplasmic reticulum, Golgi apparatus, and intermediate transport structures, and colocalized with epitope-tagged VIP36. Temperature shift and pharmacological experiments indicated VIP36-SP-FP recycled in the early secretory pathway, exhibiting trafficking representative of a class of transmembrane cargo receptors, including the closely related lectin ERGIC53. VIP36-SP-FP trafficking structures comprised tubules and globular elements, which translocated in a saltatory manner. Simultaneous visualization of anterograde secretory cargo and VIP36-SP-FP indicated that the globular structures were pre-Golgi carriers, and that VIP36-SP-FP segregated from cargo within the Golgi and was not included in post-Golgi TCs. Organelle-specific bleach experiments directly measured the exchange of VIP36-SP-FP between the Golgi and endoplasmic reticulum (ER). Fitting a two-compartment model to the recovery data predicted first order rate constants of 1.22 ± 0.44%/min for ER → Golgi, and 7.68 ± 1.94%/min for Golgi → ER transport, revealing a half-time of 113 ± 70 min for leaving the ER and 1.67 ± 0.45 min for leaving the Golgi, and accounting for the measured steady-state distribution of VIP36-SP-FP (13% Golgi/87% ER). Perturbing transport with AlF4−treatment altered VIP36-SP-GFP distribution and changed the rate constants. The parameters of the model suggest that relatively small differences in the first order rate constants, perhaps manifested in subtle differences in the tendency to enter distinct TCs, result in large differences in the steady-state localization of secretory components.

M-dependence of collisional transfer of rotational energy in methyl alcohol: the (4−1 ← 30)p – (40 ← 31)s system

1978 ◽  
Vol 56 (11) ◽  
pp. 1417-1421 ◽  
Author(s):  
R. M. Lees
Keyword(s):  
Energy Transfer ◽  
Matrix Element ◽  
Simple Model ◽  
Transition Rate ◽  
Double Resonance ◽  
Rotational Energy ◽  
Dipole Matrix Element ◽  
Level System ◽  
Rotational Energy Transfer ◽  
Good Agreement

An M-resolved microwave double resonance study of collision-induced rotational energy transfer has been carried out for the (4−1 ← 30)p – (40 ← 31)s four-level system of CH3OH. Spectra are reported for each distinct combination of pump and signal M-components. The observed M-dependence of the double resonance signals is in good agreement with a very simple model of the collisional transfer in which a transition rate constant is taken to depend only on the square of the dipole matrix element for the transition.

Performance and Modelling of a Highway Wet Detention Pond Designed for Cold Climate

2009 ◽  
Vol 44 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Jes Vollertsen ◽  
Svein Ole Åstebøl ◽  
Jan Emil Coward ◽  
Tor Fageraas ◽  
Asbjørn Haaning Nielsen ◽  
...  
Keyword(s):  
Rate Constants ◽  
Pond Water ◽  
Pollutant Removal ◽  
Cold Climate ◽  
Traffic Load ◽  
Substantial Part ◽  
First Order ◽  
Detention Pond ◽  
Time Of Year ◽  
Wet Detention Pond

Abstract A wet detention pond in Norway has been monitored for 12 months. The pond receives runoff from a highway with a traffic load of 42,000 average daily traffic. Hydraulic conditions in terms of inflow, outflow, and pond water level were recorded every minute. Water quality was monitored by volume proportional inlet and outlet samples. During most of the year, excellent pollutant removal was achieved; however, during two snowmelt events the pollutant removal was poor or even negative. The two snowmelt events accounted for one third of the annual water load and for a substantial part of the annual pollutant discharge. The performance of the pond was analyzed using a dynamic model and pollutant removal was simulated by first-order kinetics. Good agreement between measurement and simulation could be achieved only when choosing different first-order rate constants for different parts of the year. However, no relation between the rate constants obtained and the time of year could be identified, and neither did the rate constants for different pollutants correlate. The study indicates that even detailed measurements of pollutant input and output allow only average performance to be simulated and are insufficient for simulating event-based variability in pond performance.

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

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