Performance of two Magnesium borate compounds, with thermoluminescent properties, to γ-rays and neutrons

The heart is generally considered a radioresistant organ, and has received relatively little study after total-body irradiation with doses below the acutely lethal range. Some late damage in the irradiated heart has been described at the light microscopic level. However, since the dimensions of many important structures of the blood vessel wall are submicroscopic, investigators have turned to the electron microscope for adequate visualization of histopathological changes. Our studies are designed to evaluate ultrastructural changes in the mouse heart, particularly in the capillaries and muscle fibers, for 18 months after total-body exposure, and to compare the effects of 240 rad fission neutrons and 788 rad 60Co γ-rays.Three animals from each irradiated group and three control mice were sacrificed by ether inhalation at 4 days, and at 1, 3, 6, 12, and 18 months after irradiation. The thorax was opened and the heart was fixed briefly in situwith Karnofsky's fixative.

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CONTRIBUTIONS OF A2-, p'A-, AND RESONANT TERMS IN INELASTIC SCATTERING OF γ-RAYS BY DEEPLY BOUND ELECTRONS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19879143 ◽

1987 ◽

Vol 48 (C9) ◽

pp. C9-815-C9-818

Author(s):

Y. OHMURA ◽

S. SATO

Keyword(s):

Inelastic Scattering ◽

Γ Rays ◽

Bound Electrons

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Study of nickel-molybdenum catalysts for methanation of carbon monoxide

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19800783 ◽

1980 ◽

Vol 45 (3) ◽

pp. 783-790 ◽

Cited By ~ 1

Author(s):

Petr Taras ◽

Milan Pospíšil

Keyword(s):

Carbon Monoxide ◽

Catalytic Activity ◽

Mixed Oxides ◽

Minor Component ◽

Fast Neutrons ◽

Scanning Calorimetry ◽

Low Concentrations ◽

Γ Rays ◽

Molybdenum Catalysts ◽

Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

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Gravitational Collapse versus Thermonuclear Explosion of Degenerate Stellar Cores

International Astronomical Union Colloquium ◽

10.1017/s0252921100026373 ◽

1994 ◽

Vol 147 ◽

pp. 186-213

Author(s):

J. Isern ◽

R. Canal

Keyword(s):

Neutron Star ◽

White Dwarfs ◽

Light Curves ◽

Type Ia Supernovae ◽

Radioactive Elements ◽

Border Line ◽

Thermonuclear Explosion ◽

Type Ia ◽

Γ Rays ◽

Ia Supernovae

AbstractIn this paper we review the behavior of growing stellar degenerate cores. It is shown that ONeMg white dwarfs and cold CO white dwarfs can collapse to form a neutron star. This collapse is completely silent since the total amount of radioactive elements that are expelled is very small and a burst of γ-rays is never produced. In the case of an explosion (always carbonoxygen cores), the outcome fits quite well the observed properties of Type Ia supernovae. Nevertheless, the light curves and the velocities measured at maximum are very homogeneous and the diversity introduced by igniting at different densities is not enough to account for the most extreme cases observed. It is also shown that a promising way out of this problem could be the He-induced detonation of white dwarfs with different masses. Finally, we outline that the location of the border line which separetes explosion from collapse strongly depends on the input physics adopted.

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The internal conversion of gamma-rays.—Part II

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1928.0208 ◽

1928 ◽

Vol 121 (787) ◽

pp. 447-456

Keyword(s):

Magnetic Field ◽

Quantum Mechanics ◽

Wave Equation ◽

Gamma Rays ◽

Internal Conversion ◽

Scalar Potential ◽

X Ray ◽

Electro Magnetic Field ◽

Γ Rays ◽

Electro Magnetic

In a previous paper the absorption of γ-rays in the K-X-ray levels of the atom in which they are emitted was calculated according to the Quantum Mechanics, supposing the γ-rays to be emitted from a doublet of moment f ( t ) at the centre of the atom. The non-relativity wave equation derived from the relativity wave equation for an electron of charge — ε moving in an electro-magnetic field of vector potential K and scalar potential V is h 2 ∇ 2 ϕ + 2μ ( ih ∂/∂ t + εV + ih ε/μ c (K. grad)) ϕ = 0. (1) Suppose, however, that K involves the space co-ordinates. Then, (K. grad) ϕ ≠ (grad . K) ϕ , and the expression (K . grad) ϕ is not Hermitic. Equation (1) cannot therefore be the correct non-relativity wave equation for a single electron in an electron agnetic field, and we must substitute h 2 ∇ 2 ϕ + 2μ ( ih ∂/∂ t + εV) ϕ + ih ε/ c ((K. grad) ϕ + (grad. K) ϕ ) = 0. (2)

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