scholarly journals From the Editor

Radiocarbon ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. ii-ii
Author(s):  
Austin Long
Keyword(s):  
Neutron Activation ◽  
Global Scale ◽  
Airport Security ◽  
Thermal Neutron Activation ◽  
X Rays ◽  
Security Technology ◽  
New Device ◽  
The Wall Street Journal ◽  
High Concentrations ◽  
Security Device

A few of our colleagues, upon receiving a radiocarbon date younger than they expected, have wondered if X-rays in airport security devices might have increased their 14C content. Unfortunately for them, our colleagues have been forced to find alternate explanations for the uncooperative dates. Airport X-rays simply cannot produce 14C. However, a new security technology is almost ready for installation at Kennedy Airport for some international flights, and, according to the Wall Street Journal, 100 additional units are planned for other high-risk airports. The new device will detect high concentrations of nitrogen (a component in explosives) by thermal neutron activation (TNA). Since TNA on a global scale is the process by which nature produces virtually all 14C in the atmosphere, some 14C must be produced in high-nitrogen materials, such as bones, as they pass through a neutron activation airport security device. The question important to the radiocarbon dating community is how much effect can the 14C thus produced have on the 14C date?

Characterization of Industrial Wastes, Glass and Ceramic Wool

2012 ◽  
Vol 727-728 ◽  
pp. 1585-1590
Author(s):  
Neuza Evangelista ◽  
Jorge Alberto Soares Tenório ◽  
José Roberto Oliveira ◽  
Paulo R. Borges ◽  
Taiany Coura M. Ferreira
Keyword(s):  
Average Particle Size ◽  
Amorphous Structure ◽  
Glass Wool ◽  
Industrial Wastes ◽  
Average Particle ◽  
X Rays ◽  
Ceramic Fibers ◽  
High Concentrations ◽  
Reduction Of Energy Consumption ◽  
Superior Corrosion Resistance

Ceramic fibers are characterized by their light weight, high degree of purity, low heat storage, low thermal conductivity, thermal shock resistance and superior corrosion resistance in high-temperature environments. In addition, they can be produced extensively in substitution to all materials used in the coating of almost all heating equipment as well as contributing to the reduction of energy consumption. Such characteristics make them ideal in the coating of distributors, mufflers, heating ovens, among others, as highly demanded by the mining and metallurgical industries, among others. After use in the process of industrial production, generated waste will lose their insulation capacity and thus require safe disposal. The present work focuses specifically on ceramic and glass wools aiming at an evaluation of their recycling prospect of incorporation into cement mortars and concrete. This residues were pulverized and displayed ~30µm average particle size. The scan electronic microscopy (SEM) presented elongated, thin and straight particles, which is very different than flocular structure of cement. The X-rays diffraction revealed amorphous structure for glass wool and crystalline structure for ceramics wool. The chemical analysis showed high concentrations of Al2O3 and silica in both residues, with higher percentage of calcium oxide in glass wool.

scholarly journals A hydroxyapatite phantom material for the calibration of in vivo x-ray fluorescence systems of bone strontium and lead quantification

2021 ◽  
Author(s):  
Eric Da Silva
Keyword(s):  
Monte Carlo ◽  
Soft Tissue ◽  
Monte Carlo Simulations ◽  
Calibration Procedure ◽  
X Rays ◽  
X Ray ◽  
Total Phosphate Concentration ◽  
High Concentrations ◽  
Phantom Material

A hydroxyaptite [HAp; Ca5(PO4)3OH] phantom material was developed with the goal of improving the calibration protocol of the 125I-induced in vivo X-ray fluorescence (IVXRF) system of bone strontium quantification with further application to other IVXRF bone metal quantification systems, particulary those associated with bone lead quantification. It was found that calcium can be prepared pure of inherent contamination from strontium (and other elements) through a hydroxide precipitation producing pure Ca(OH)2, thereby, allowing for the production of a blank phantom which has not been available previously. The pure Ca(OH)2 can then be used for the preparation of pure CaHPO4 ⋅ 2H2O. A solid state pure HAp phantom can then be prepared by reaction of Ca(OH)2 and CaHPO4 ⋅ 2H2O mixed as to produce a Ca/P mole ratio of 1.67, that in HAp and the mineral phase of bone, in the presence of a setting solution prepared as to raise the total phosphate concentration of the solution by increasing the solubility CaHPO4 ⋅ 2H2O and thereby precipitating HAp. The procedure can only be used to prepare phantoms in which doping with the analyte does not disturb the Ca/P ratio substantially. In cases in which phantoms are to be prepared with high concentrations of strontium, the cement mixture can be modified as to introduce strontium in the form of Sr(OH)2 ⋅ 8H2O as to maintain a (Ca + Sr)/P ratio of 1.67. It was found by both X-ray diffraction spectrometry and Raman spectroscopy studies that strontium substitutes for calcium as in bone when preparing phantoms by this route. The necessity for the blank bone phantoms was assessed through the first blank bone phantom measurement and Monte Carlo simulations. It was found that for the 125I-induced IVXRF system of bone strontium quantification, the source, 125I brachytherapy seeds may be contributing coherently and incoherently scattered zirconium X-rays to the measured spectra, thereby requiring the use of the blank bone phantom as a means of improving the overall quantification methodology. Monte Carlo simulations were employed to evaluate any improvement by the introduction of HAp phantoms into the coherent normalization-based calibration procedure. It was found that HAp phantoms remove the need for a coherent conversion factor (CCF) thereby potentially increasing accuracy of the quantification. Further, it was found that in order for soft tissue attenuation corrections to be possible using spectroscopic information alone, HAp along with a suitable soft tissue surrogate material need to be employed. The HAp phantom material was used for the evaluations of portable X-ray analyzer systems for their potential for IVXRF quantification of lead and strontium with a focus on a comparison between tungsten, silver and rhodium target systems. Silver and rhodium target X-ray tube systems were found to be comparable for this quantification.

scholarly journals Analiza tkiva okrog omajanih umetnih kolčnih debel iz poliacetala z uporabo nuklearnih metod

2015 ◽  
Vol 84 (3) ◽  
Author(s):  
Klemen Stražar ◽  
Matjaž Kavčič ◽  
Žiga Šmit ◽  
Jure Simčič ◽  
Radojko Jaćimović ◽  
...  
Keyword(s):  
Neutron Activation ◽  
Thermal Neutron ◽  
Indirect Detection ◽  
Thermal Neutron Activation ◽  
Wear Particles ◽  
Hip Prostheses ◽  
Nuclear Methods ◽  
Femoral Stems ◽  
The One ◽  
Pixe Method

IntroductionThe influence of polyacetal wear particles on aseptic loosening of non-cemented isoelastic femoral stems with polyacetal coating remains unclear. The aim of our study was to use nuclear methods to prove the presence of polyacetal wear particles, to determine their morphology and to check their distribution in the tissues around loosend hip prosthetic components.MethodsTissue samples obtained during retrieval of 4 aseptic loosened primary hip prostheses with isoelastic stems made of polyacetal were subjected to nuclear analyses. Proton microbrobe method (mikro-PIXE) was used to prove the presence of polyacetal wear particles and to check for their morphology by detection of barium, which is molecularly in BaSO4 embedded in polyacetal. Thermal neutron activation was used to determine distribution pattern of polyacetal wear in the peri-prosthetic tissues.ResultsAgainst expectations, polyacetal wear particles were found rather rare, larger than 100 µm and present in pseudo-membrane samples around the loosened stem, but virtually absent in tissues away from their origin. Concentration of BaSO4 in polyacetal wear particles in pseudo-membrane samples was similar to the one in polyacetal coating (conc. Ba = 14217 µg/g and 14800 µg/g, respectively).ConclusionAccording to the results, the primary cause of the loosening of the isoelastic stems with polyacetal coating is most probably mechanical restlessness, which is responsible for local production of the large polyacetal wear particles responsible to accelerate the process of loosening. PIXE method and thermal neutron activation are sensitive quantitative nuclear methods suitable for direct or indirect detection of wear particles in the tissue around loosened prostheses and to determine morphology of wear particles and their distribution in the tissues.

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