Radiation Damage and Its Annealing in Sodium Silica Glass

1986 ◽  
Vol 84 ◽  
Author(s):  
T.D. Mark ◽  
W. Ritter
Keyword(s):  
Temperature Dependence ◽  
Radiation Damage ◽  
Absorption Spectroscopy ◽  
Exponential Function ◽  
Annealing Time ◽  
Silica Glass ◽  
Fission Fragments ◽  
Radiation Sources ◽  
Single Exponential Function ◽  
Single Exponential

AbstractAnnealing of radiation damage in artificial sodium silica glass has been studied by absorption spectroscopy for different radiation sources (fission fragments produced by n,f reactions, alpha decays produced by n, α reactions, and 2 MeV electrons) as a function of annealing time and temperature. The annealing observed can be described best by a single exponential functionA(t) = a exp (− αt)with an Arrhenius type temperature dependence of the annealing coefficient αα(T) = α0 exp (− EA/kT)For the three different radiation sources similar activitation energies EA were deduced from the data. Possible annealing processes are discussed.

Myocardial blood flow determined with krypton 85 in unanesthetized dogs

1962 ◽  
Vol 203 (1) ◽  
pp. 122-124 ◽  
Author(s):  
J. A. Herd ◽  
M. Hollenberg ◽  
G. D. Thorburn ◽  
H. H. Kopald ◽  
A. C. Barger
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Myocardial Blood Flow ◽  
Exponential Function ◽  
Scintillation Detector ◽  
Left Ventricular ◽  
Blood Flows ◽  
Single Exponential Function ◽  
Single Exponential ◽  
Rapid Measurements

Serial, rapid measurements of left ventricular myocardial blood flow in trained, unanesthetized dogs have been made by injecting krypton 85 through chronically implanted coronary artery catheters and counting with an external scintillation detector. Precordial radioactivity declined as a single exponential function during the first 2 min after injection, suggesting a single rate of myocardial blood flow. Simultaneous estimations with Kr85 and blood flowmeters in acute experiments established the accuracy and reproducibility of the technique. Myocardial blood flows between 40 and 55 ml/100 g/min were observed repeatedly in three well-trained, unanesthetized dogs in the basal state.

Annealing and Leaching Studies With Natural and Artificial Obsidian Glass

1987 ◽  
Vol 112 ◽  
Author(s):  
T. D. MÄrk ◽  
G. Walder
Keyword(s):  
Temperature Dependence ◽  
Exponential Function ◽  
Annealing Time ◽  
Radiation Doses ◽  
Leaching Rate ◽  
Fission Tracks ◽  
Leaching Experiments ◽  
Induced Fission ◽  
Obsidian Glass ◽  
Kinetics Of

AbstractAnnealing kinetics of fission tracks (produced by induced fission of U235 in natural and artificial (doped) obsidian glass has been studied by etching microscopy as a function of annealing time and temperature. The observed annealing characteristics can be best decribed by a two term exponential function with an Arrhenius type temperature dependence of the annealing coefficients. The activation energies deduced are (0.94 ± 0.16)eV and (1.04 ± 0.15)eV for artificial obsidian and (0.83 ± O.13)eV and (0.60 ± 0.16)eV for natural (fossil) obsidian, respectively. In addition, leaching experiments of obsidian samples exposed to different radiation, doses and rates have been made at two different leachate temperatures. At a temperature of 60°C the leaching rate of irradiated samples is much larger than that of unirradiated samples, whereas at a temperature of 90°C observed leaching rates are similar.

Whole-cell and single-channel recordings of GABA-gated currents in cultured chick cerebral neurons

1988 ◽  
Vol 59 (2) ◽  
pp. 495-513 ◽  
Author(s):  
D. S. Weiss ◽  
E. M. Barnes ◽  
J. J. Hablitz
Keyword(s):  
Membrane Potential ◽  
Time Constant ◽  
Exponential Function ◽  
Single Channel ◽  
Synaptic Currents ◽  
Whole Cell ◽  
Cerebral Neurons ◽  
Single Exponential Function ◽  
Single Exponential ◽  
Conductance State

1. gamma-Aminobutyric acid (GABA) (10-500 microM) was applied to cultured chick cerebral neurons by pressure ejection, and the resulting currents (IGABA) were recorded using standard whole-cell voltage-clamp techniques. Plots of the peak IGABA as a function of membrane potential were nonlinear with an outwardly rectifying appearance. 2. IGABA decayed during a prolonged application of GABA. This decay was associated with a decline in the conductance of the cell, suggesting that the decline in IGABA was principally due to receptor desensitization. 3. After 5-7 days in culture, whole-cell recordings revealed the presence of spontaneous synaptic currents. These currents were presumed to be GABA-gated inhibitory postsynaptic currents (IPSCs) because they reversed at the Cl- equilibrium potential (ECl-), were blocked by picrotoxin (25 microM), and were prolonged by pentobarbital (50 microM). 4. Synaptic currents were analyzed by fitting exponential functions to their decay. In normal recording saline, 68% of the decays analyzed could be adequately described by a single exponential function. Two exponentials were necessary to describe the decay of the other 32%. The time constant of the decay (for those adequately fitted by a single exponential) increased with depolarization, from an average value of 15 ms at -80 mV to 60 ms at +40 mV. 5. A relationship was noted between IPSC amplitude and decay time constant; IPSCs with larger peak amplitudes had a slower decay. One possible explanation considered for this finding was that transmitter persists in the synaptic cleft and rebinds to the receptors, thus prolonging the decay of the IPSC. 6. Consistent with the above hypothesis was the observation that the decays of miniature IPCSs (examined under conditions of reduced transmitter release) were faster, showed less variability, and were all adequately described by a single exponential function. Furthermore, the decay times were independent of the membrane potential, suggesting that the kinetic parameters of the GABA channel which shape the decay of these miniature IPSCs are independent of voltage. 7. Single-channel activity underlying whole-cell GABA responses could be recorded in isolated outside-out and inside-out patches of membrane. In isotonic choline chloride, single-channel amplitudes were linearly related to voltage and reversed at -1.8 +/- 11.0 mV (n = 12). Under these conditions, the channel had a main conductance state of 20.8 +/- 3.4 pS (n = 12). Transitions were observed from this main conductance state to other conductance states, e.g., two subconductance states of 6 and 12 pS and one supraconductance state of 30 pS.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A harmonic analysis of exponential decay

2020 ◽  
Author(s):  
David Lawunmi ◽  
Soodamani Ramalingam
Keyword(s):  
Harmonic Analysis ◽  
Exponential Function ◽  
Exponential Decay ◽  
Harmonic Functions ◽  
Exponential Functions ◽  
Single Exponential Function ◽  
Single Exponential

We analyse the decay of a single exponential function and develop an algorithm to determine the exponent and the constant, C, (C exp(-kt)) associated with this function . In essence this approach involves `transforming' exponential functions into harmonic functions. This manoeuvre allows techniques that are used to analyse harmonic functions to be used to characterise decaying exponential functions.

Study on Wear of Grinding Wheels: 1—Bond Fracture in Grinding Wheels

1963 ◽  
Vol 85 (1) ◽  
pp. 39-42 ◽  
Author(s):  
Hiroyuki Yoshikawa ◽  
Toshio Sata
Keyword(s):  
Brittle Fracture ◽  
Wear Rate ◽  
Exponential Function ◽  
Grinding Force ◽  
Theoretical Interpretation ◽  
Grinding Wheels ◽  
Double Exponential ◽  
Double Exponential Function ◽  
Single Exponential Function ◽  
Single Exponential

Fracturing of bond bridges in grinding wheels is explained from the standpoint of brittle-fracture. It is shown that the wear rate of grinding wheels can be expressed as the single exponential function of the grinding speed and as the double exponential function of the grinding force. Experimental results are shown to confirm the theoretical interpretation.

Fast approximate solutions of transient EM response to a target buried beneath a conductive overburden

Geophysics ◽  
1993 ◽  
Vol 58 (6) ◽  
pp. 810-817 ◽  
Author(s):  
Guimin Liu ◽  
Michael W. Asten
Keyword(s):  
Exponential Function ◽  
Free Space ◽  
Approximate Solutions ◽  
Scale Model ◽  
Target Response ◽  
Delay Effect ◽  
Wire Loop ◽  
Transient Electromagnetic ◽  
Single Exponential Function ◽  
Single Exponential

We derive fast transient electromagnetic (TEM) solutions for a thin‐plate conductive target buried in a resistive host rock overlain by thin conductive overburden. For this model, the total TEM field is composed of the overburden response, which is known analytically, and the target response that is approximated by a wire loop. Thus the transient response of the target in free space is approximated with a single exponential function. The interaction between the target and the overburden is approximated by convolving the overburden‐delayed driving field with the exponential function. The target response is then computed from the wire loop by the Biot‐Savart law in free space, thus neglecting the second overburden‐delay effect. Including the second overburden‐delay effect does not yield significantly improved results. The approximate solutions agree reasonably well with scale model and numerical results, but their computation is more than 100 times faster than conventional methods and can be easily done on a small personal computer.

scholarly journals Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra Determination

2016 ◽  
Vol 47 (3) ◽  
pp. 755 ◽  
Author(s):  
J.A. Briz ◽  
A.-A. Zakari-Issoufou ◽  
M. Fallot ◽  
A. Porta ◽  
A. Algora ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Total Absorption ◽  
Fission Fragments ◽  
Reactor Antineutrino

Characterization of Radiation Damage at the Nb Site in Natural Pyrochlores and Samarskites by X-Ray Absorption Spectroscopy

1988 ◽  
Vol 127 ◽  
Author(s):  
R. B. Greegor ◽  
F. W. Lytle ◽  
B. C. Chakoumakos ◽  
G. R. Lumpkin ◽  
J. K. Warner ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Long Range ◽  
Absorption Spectroscopy ◽  
Alpha Decay ◽  
Long Range Order ◽  
Static Disorder ◽  
Annealed Condition ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTX-ray absorption spectroscopy has been used to investigate the Nb B-site in pyrochlores (A1.2B2O6Y0–1, Fd3m, Z=8) and samarskites (A3B5O16) in both metamict and annealed condition. The XANES and EXAFS measurements indicate significant changes in pyrochlore and smaller changes in samarskite as a result of radiation damage. In the metamict state the Nb site in both pyrochlores and samarskites is similar to Nb in Nb2O5. Short Nb-O (1.65Å) bonds are not disrupted by alpha-decay/recoil-nuclei events as much as longer bonds (2.00Å). This increases the asymmetry and static disorder at the local Nb site while long range order is greatly diminished resulting in considerable distribution in Nb-M distances and bond angles.

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