Theoretical treatment of radiation trapping: Steady-state conditions and quenching experiment

1994 ◽  
Vol 49 (2) ◽  
pp. 787-793 ◽  
Author(s):  
Xingxiao Ma ◽  
Re Lai
Keyword(s):  
Steady State ◽  
Theoretical Treatment ◽  
Radiation Trapping

FURTHER CONSIDERATIONS ON THE CALCULATIONS OF SECRETION RATES. A CORRECTION

1961 ◽  
Vol 38 (3) ◽  
pp. 469-472 ◽  
Author(s):  
K. R. Laumas ◽  
J. F. Tait ◽  
S. A. S. Tait
Keyword(s):  
Steady State ◽  
Compartmental Model ◽  
Single Injection ◽  
Previous Treatment ◽  
Urinary Metabolite ◽  
Theoretical Treatment ◽  
Basic Equations ◽  
Special Circumstances ◽  
Secretion Rates

ABSTRACT Reconsideration of the question of the validity of the calculations of the secretion rates from the specificity activity of a urinary metabolite after the single injection of a radioactive hormone has led us to conclude that the basic equations used in a previous theoretical treatment are not generally applicable to the nonisotopic steady state if the radioactive steroid and hormone are introduced into the same compartment. If this is so, in a two compartmental model with metabolism occurring in both pools, it is now shown that the calculation (S = R — τ) is rigorously valid if certain precautions are taken. This is in contrast to the previous treatment which concluded (in certain special circumstances) that the calculation might not be correct. However, if the hormone is secreted in both compartments and the radioactive steroid is injected into only one, then the calculation (S = R — τ) may not be correct in certain circumstances as was previously concluded (Laumas et al. 1961).

THEORY OF THE TRANSIENT PHASE IN AN ENZYME SYSTEM INVOLVING TWO ENZYME-SUBSTRATE COMPLEXES: THE CASE OF THE FORMATION OF PRODUCTS FROM THE FIRST COMPLEX

1959 ◽  
Vol 37 (4) ◽  
pp. 737-743 ◽  
Author(s):  
Ludovic Ouellet ◽  
James A. Stewart
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Active Site ◽  
Substrate Concentration ◽  
Enzyme System ◽  
Kinetic Scheme ◽  
Enzyme Concentration ◽  
Theoretical Treatment ◽  
Transient Phase ◽  
Enzyme Substrate

A theoretical treatment is worked out for the kinetic scheme[Formula: see text]in which the concentration of P1 is followed. The steady-state and transient phase equations are obtained subject to the condition that the substrate concentration is greatly in excess of the enzyme concentration. The conditions under which evidence in favor of this mechanism can be obtained from experimental data are discussed. Under certain conditions, the weight of the enzyme corresponding to one active site can be determined. Methods for the evaluation of the different constants are described.

Effects of Diffusion in the Oxidative Degradation of Vulcanized Rubbers. I. Rate of Chain Scission in the Steady State

1977 ◽  
Vol 50 (1) ◽  
pp. 43-48 ◽  
Author(s):  
K. Ono ◽  
A. Kaeriyama ◽  
K. Murakami
Keyword(s):  
Oxygen Consumption ◽  
Steady State ◽  
Diffusion Constant ◽  
Oxidative Degradation ◽  
Relaxation Method ◽  
Chain Scission ◽  
Simple Relation ◽  
Theoretical Treatment ◽  
Steady State Condition ◽  
True Activation Energy

Abstract The effects of diffusion in the oxidation of cis-1,4-polyisoprene vulcanizates were investigated by means of the stress relaxation method. It was assumed that the diffusion of oxygen is coupled with first-order oxygen consumption and that the rate of chain scission is proportional to the rate of oxygen consumption. The diffusion equation of this process was solved under the steady-state condition to give a simple relation between the rate of chain scission and the film thickness. The experimental results were in good agreement with the theoretical treatment. The true activation energy as well as the ratio of the rate of oxidation k to the diffusion constant D could be estimated.

scholarly journals Resonance scattering by auroral N<sub>2</sub><sup>+</sup>: steady state theory and observations from Svalbard

2009 ◽  
Vol 27 (9) ◽  
pp. 3465-3478 ◽  
Author(s):  
O. Jokiaho ◽  
B. S. Lanchester ◽  
N. Ivchenko
Keyword(s):  
Steady State ◽  
Resonance Scattering ◽  
State Theory ◽  
Theoretical Treatment ◽  
Ion Chemistry ◽  
Echelle Spectrograph ◽  
Negative Band ◽  
Auroral Electron ◽  
High Throughput Imaging ◽  
Relationship Of

Abstract. Studies of auroral energy input at high latitudes often depend on observations of emissions from the first negative band of ionised nitrogen. However, these emissions are affected by solar resonance scattering, which makes photometric and spectrographic measurements difficult to interpret. This work is a statistical study from Longyearbyen, Svalbard, Norway, during the solar minimum between January and March 2007, providing a good coverage in shadow height position and precipitation conditions. The High Throughput Imaging Echelle Spectrograph (HiTIES) measured three bands of N2+ 1N (0,1), (1,2) and (2,3), and one N2 2P band (0,3) in the magnetic zenith. The brightness ratios of the N2+ bands are compared with a theoretical treatment with excellent results. Balance equations for all important vibrational levels of the three lowest electronic states of the N2+ molecule are solved for steady-state, and the results combined with ion chemistry modelling. Brightnesses of the (0,1), (1,2) and (2,3) bands of N2+ 1N are calculated for a range of auroral electron energies, and different values of shadow heights. It is shown that in sunlit aurora, the brightness of the (0,1) band is enhanced, with the scattered contribution increasing with decreasing energy of precipitation (10-fold enhancements for energies of 100 eV). The higher vibrational bands are enhanced even more significantly. In sunlit aurora the observed 1N (1,2)/(0,1) and (2,3)/(0,1) ratios increase as a function of decreasing precipitation energy, as predicted by theory. In non-sunlit aurora the N2+ species have a constant proportionality to neutral N2. The ratio of 2P(0,3)/1N(0,1) in the morning hours shows a pronounced decrease, indicating enhancement of N2+ 1N emission. Finally we study the relationship of all emissions and their ratios to rotational temperatures. A clear effect is observed on rotational development of the bands. It is possible that greatly enhanced rotational temperatures may be a signature of ion upflows.

scholarly journals THEORETICAL TREATMENT OF RADIATION TRAPPING IN A MULTIPLE LINES COUPLED SYSTEM

1997 ◽  
Vol 46 (1) ◽  
pp. 42
Author(s):  
LAI RE ◽  
WANG JIAN ◽  
WANG CHU-JI ◽  
MA XING-XIAO
Keyword(s):  
Coupled System ◽  
Theoretical Treatment ◽  
Radiation Trapping

THEORY OF THE TRANSIENT PHASE IN KINETICS, WITH SPECIAL REFERENCE TO ENZYME SYSTEMS: II. THE CASE OF TWO ENZYME–SUBSTRATE COMPLEXES

1956 ◽  
Vol 34 (2) ◽  
pp. 146-150 ◽  
Author(s):  
Ludovic Ouellet ◽  
Keith J. Laidler
Keyword(s):  
Steady State ◽  
Substrate Concentration ◽  
Kinetic Scheme ◽  
Rate Equations ◽  
Theoretical Treatment ◽  
Transient Phase ◽  
Enzyme Substrate ◽  
Enzyme Systems ◽  
Steady State Rate ◽  
State Rate

A theoretical treatment is worked out for the kinetic scheme[Formula: see text]in which two enzyme–substrate complexes are formed consecutively. The steady-state rate equations are obtained, and equations are given for the transient phase subject to the condition that the substrate concentration is greatly in excess of that of the enzyme. Some kinetic consequences of the resulting equations are discussed.

scholarly journals Steady State Flow in the Cigarette and its Influence on Pressure Drop - Die stationäreStrömung in der Cigarette und derenEinfluß auf den Zugwiderstand

1992 ◽  
Vol 15 (3) ◽  
pp. 93-122
Author(s):  
H Gaißer
Keyword(s):  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Flow Rate ◽  
Unit Length ◽  
Parameter Study ◽  
Model Parameters ◽  
Theoretical Treatment ◽  
Flow Process ◽  
Wide Range

AbstractA theoretical treatment of steady state fluid mechanics of filtered cigarettes has been developed. By assuming laminar fluid flow, the well knownKozeny-Carman equation has been used to evaluate the flow resistance of the tobacco rod and the linear relationship of cigarette pressure drop to flow rate. Based on this relationship, models with distributed parameters (using impedances per unit length and differential equations) and lumped parameters (using a four terminal network of flow impedances and difference equations) have been established. These were used to calculate spatial flow variables such as pressure drop, volumetric flow rate and degree of ventilation. The effects of changes in coal resistance and reduction in rod length during smoking are demonstrated in a parameter study. A great advantage of mathematical modeling based on physical principles is the wide range of validity which allows a deeper insight into the behaviour of the fluid flow process. This is illustrated using a canonical example. Invariant model parameters such as the characteristic wave impedance and the propagation coefficient have been calculated and are presented as measurable. In order to calculate the dynamic fluid flow pattern of filtered cigarettes smoked on a conventional smoking machine, the model must be extend to include kinetic terms according to the Bernouilli equation. This will be presented in a later paper.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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