• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 58
  • 56
  • 9
  • 8
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 500
  • 500
  • 120
  • 118
  • 103
  • 94
  • 89
  • 88
  • 58
  • 52
  • 48
  • 45
  • 44
  • 44
  • 41
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Inactivation synergy between high energy neutrons and ⁶⁰Co gamma rays

Slabbert, Jacobus Petrus January 1993 (has links)
The interaction between sublesions produced by neutrons [p(66)/Be and d(16)/Be] and ⁶⁰Co γ-rays was investigated using mammalian cells, meristematic cells and human lymphocytes. The quality of each radiation source was quantified in terms of molecular yield per unit dose absorbed in a ferrous sulphate xylenol orange solution and was found to vary inversely with the mean LET of the radiation field. Inactivation parameters determined for mammalian and meristematic cells were not significantly different following simultaneous or sequential exposures to d(16)/Be neutrons and ⁶⁰Co γ-rays. Synergistic interaction was observed to be most pronounced in a radiation mixture consisting of about one part neutrons and three parts photons and appeared to be optimal at approximately 5 Gy. This phenomenon led to dose enhancement ratios that increase with radioresistance. Multi-target parameters indicated that on a per gray basis, priming doses of p(66)/Be neutrons and ⁶⁰Co γ-rays induce comparative levels of sublethal damage. However, non-parametric analysis of the survival data showed that mammalian cells regard a priming dose of neutrons as somewhat less effective than an iso-effective photon dose. A greater measure of synergy was observed between photons and priming doses of neutrons with less build-up. This is however mainly due to higher levels of biological damage induced with a more potent configuration of secondary charged particles. Interaction factors compared at levels of iso-effect tend to be smaller when the LET of the priming dose was increased. Split-doses of neutrons in the absence of build-up resulted in "negative" repair. The validity of proposed biophysical models was tested using meristematic cells, as the response of these cells show an apparent absence of intertrack damage. Contrary to expectations, synergistic interaction was observed for both growth delay measurements and micronuclear formations. Chromosome aberrations showed synergy between neutron and photon damage in human lymphocytes, as predicted by interaction functi ons. However, the synergistic interaction noted with micronuclear formation in binucleate cells was at variance with predictions based on biophysical models.
12

The track structure of ionising particles and their application to radiation biophysics

Briden, P. E. January 1988 (has links)
No description available.
13

Oxidative and nonoxidative effects of ionising radiation on palm olein

Endinkeau, K. January 1988 (has links)
No description available.
14

A study of biophysical mechanisms of damage by ionizing radiation to mammalian cells in vitro

Chen, C-Z. January 1987 (has links)
No description available.
15

Radiation exposure to the surgeon during axillary sentinel lymph node biopsy

Harran, Nadine 25 April 2014 (has links)
Introduction To measure the radiation exposure to the surgeon during axillary sentinel lymph node biopsy using the radioactive isotope technetium-99m. Method A prospective analysis of 36 patients undergoing axillary sentinel lymph node biopsy using technetium-99m, between 15th January 2013 to the 20th February 2013.. Results The exposure to the surgeon during axillary sentinel lymph node dissection was measured in 36 patients by placing a thermoluminescent dosimeter (TLD) on the surgeon’s finger. The TLDs recorded the total radiation exposure to the surgeon. The recommended occupational dose limit for non radiation workers extremity exposure is less than 500 μSv. The analysed and extrapolated data showed an average exposure dose to the surgeon per patient of 2.7 μSv. Conclusion One surgeon would need to perform more than 85 such procedures per year in order to exceed the advised annual extremity dose limit. The data also suggests that regular measurements of radiation exposure and radiation protective measures need not be undertaken in theatres where surgeons are working with radioactive isotope for axillary sentinel lymph node biopsies.
16

Effects of solar ultraviolet radiation on fish with particular respect to the culture of turbot and gilthead bream

Lake, Nicholas Charles Hermon January 1990 (has links)
No description available.
17

Estudo de danos de irradiacao com neutrons rapidos por meio de ultra-som em cimento Portland

ROSA, ALEXANDRE A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:36:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:12Z (GMT). No. of bitstreams: 1 11270.pdf: 1708298 bytes, checksum: b3e40379add2b8c1fdf91872d512f53f (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
18

Estudo de danos de irradiacao com neutrons rapidos por meio de ultra-som em cimento Portland

ROSA, ALEXANDRE A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:36:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:12Z (GMT). No. of bitstreams: 1 11270.pdf: 1708298 bytes, checksum: b3e40379add2b8c1fdf91872d512f53f (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
19

Radiation Effects on Low-dimensional Carbon System

Wang, Jing 16 December 2013 (has links)
Ion irradiation has been known to be an effective tool for structure modification with micro/nano-scale precision. Recently, demonstrations have been made for nano-machining, such as the cutting and welding of carbon nanotubes. Understanding the fundamental effects of ion irradiation on carbon nanotubes is critical for advancing this technique as well as for scientific curiosity. Molecular dynamics modeling was performed to study irradiation stability, structural changes, and corresponding thermal properties. In our study, Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used to perform atomic scale simulation. In order to understand size and geometry effects on carbon damage creation, the threshold energy of displacement was calculated as a function of recoiling angles for both single-walled and multi-walled nanotubes. A strong directional dependence was found to exist in different shells of multi-walled carbon nanotubes. We found that carbon atoms on the innermost tube were more susceptible to be displaced toward the center of axis. The calculation matrix was further extended to nanotubes having different diameters for a full-scale understanding of the creation of defects. Besides studies on defects creation, thermal properties of carbon nanotubes were studied via a simplified model of the carbon nanotube network. Thermal conductivity, were found to be increased nearly one order of magnitude in carbon nanotube networks after irradiation and subsequent annealing. All the modeling results were compared with experimental observations either obtained from this project as a parallel study or from previous works, for the purpose of verification and validation. For experimental works, atomic scale characterization was performed by using transmission electron microscopy and the thermal conductivity measurement was characterized by using laser flash technique. Through a combination of modeling and experimentation, we proved that ion beam techniques can be used to enhance thermal conductivity in carbon nanotube bundles by inter-tube defects mediated phonon transport.
20

Estudo das medidas terapeuticas para reducao da contaminacao interna por radionuclideos

DUARTE, CELINA L. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:36:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:25Z (GMT). No. of bitstreams: 1 04450.pdf: 6009089 bytes, checksum: 03cdf0d32f27be5d40a52b81da343b93 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Page generated in 0.1312 seconds