The effect of heat treatment on the thermoluminescence of naturally-occurring calcites and their use as a gamma-ray dosimeter

2000 ◽  
Vol 32 (3) ◽  
pp. 253-272 ◽  
Author(s):  
Birol Engin ◽  
Olgun Güven
Keyword(s):  
Heat Treatment ◽  
Gamma Ray ◽  
Naturally Occurring

ASSESSMENT OF NATURAL RADIOACTIVITY IN MAIZE AND ESTIMATION OF CONCOMITANT DOSE TO NIGERIAN VIA INGESTION PATHWAY

2019 ◽  
Vol 184 (3-4) ◽  
pp. 359-362
Author(s):  
Mudassir H Yarima ◽  
M U Khandaker ◽  
A Nadhiya ◽  
M A Olatunji
Keyword(s):  
Cancer Risk ◽  
Natural Radioactivity ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry ◽  
Detailed Knowledge ◽  
Dose Limit ◽  
Annual Dose ◽  
Lifetime Cancer Risk ◽  
Environmental Media ◽  
Naturally Occurring

Abstract Uranium, thorium and potassium are the most abundant naturally occurring radioactive materials (NORMs) found in soils and other environmental media including foodstuffs. Since the human exposures to NORMs is an unavoidable phenomenon, in such a way that they can easily find their way to human being via food chain, detailed knowledge on their presence in foodstuffs is necessary to assess the radiation dose to the population. Thus, the present study concerns the assessment of natural radioactivity in maize, a staple foodstuff for Nigerian, via HPGe gamma-ray spectrometry. Activity concentrations (Bq/kg) in the maize samples were found to be in the range of 6.1 ± 0.6–8.2 ± 1.3, 2.2 ± 0.4–5.1 ± 0.7 and 288 ± 16–401 ± 24 for 226Ra, 232Th and 40K, respectively. Measured data for 226Ra and 232Th show below the world average values of 67 Bq/kg and 82 Bq/kg, respectively, while the activity of 40K exceeds the global average of 310 Bq/kg. The annual effective dose via the maize consumption was found to be far below the UNSCEAR recommended ingestion dose limit of 290 μSv/y, and the estimated lifetime cancer risk show lower than the ICRP (1991) cancer risk factor of 2.5 × 10−3 based on the additional annual dose limit of 1 mSv for general public, thus pose no adverse health risk to the Nigerian populace.

scholarly journals Naturally Occurring Radioactive Materials in Bracelets and Necklaces: Radiological Risk Evaluation

2021 ◽  
Vol 18 (21) ◽  
pp. 11170
Author(s):  
Halmat Jalal Hassan ◽  
Suhairul Hashim ◽  
Noor Zati Hani Abu Hanifah ◽  
Sib Krishna Ghoshal ◽  
Mohamad Syazwan Mohd Sanusi ◽  
...  
Keyword(s):  
Effective Dose ◽  
Gamma Ray ◽  
Annual Effective Dose ◽  
Threshold Model ◽  
Negative Ions ◽  
Radioactive Material ◽  
Gamma Ray Spectrometry ◽  
Radiological Risk ◽  
Naturally Occurring ◽  
Dose Conversion Coefficient

A particular category of jewelry is one involving bracelets and necklaces that are deliberately made to contain naturally occurring radioactive material (NORM)—purveyors making unsubstantiated claims for health benefits from the release of negative ions. Conversely, within the bounds of the linear no-threshold model, long-term use presents a radiological risk to wearers. Evaluation is conducted herein of the radiological risk arising from wearing these products and gamma-ray spectrometry is used to determine the radioactivity levels and annual effective dose of 15 commercially available bracelets (samples B1 to B15) and five necklaces (samples N16 to N20). Various use scenarios are considered; a Geant4 Monte Carlo (Geant4 MC) simulation is also performed to validate the experimental results. The dose conversion coefficient for external radiation and skin equivalent doses were also evaluated. Among the necklaces, sample N16 showed the greatest levels of radioactivity, at 246 ± 35, 1682 ± 118, and 221 ± 40 Bq, for 238U, 232Th, and 40K, respectively. For the bracelets, for 238U and 232Th, sample B15 displayed the greatest level of radioactivity, at 146 ± 21 and 980 ± 71 Bq, respectively. N16 offered the greatest percentage concentrations of U and Th, with means of 0.073 ± 0.0002% and 1.51 ± 0.0015%, respectively, giving rise to an estimated annual effective dose exposure of 1.22 mSv, substantially in excess of the ICRP recommended limit of 1 mSv/year.

scholarly journals Comparative Survival of Free Shiga Toxin 2-Encoding Phages and Escherichia coli Strains outside the Gut

1999 ◽  
Vol 65 (12) ◽  
pp. 5615-5618 ◽  
Author(s):  
Maite Muniesa ◽  
Francisco Lucena ◽  
Juan Jofre
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
River Water ◽  
Shiga Toxin ◽  
Water Environment ◽  
Somatic Coliphages ◽  
E Coli ◽  
Naturally Occurring ◽  
Shiga Toxin 2

ABSTRACT The behavior outside the gut of seeded Escherichia coliO157:H7, naturally occurring E. coli, somatic coliphages, bacteriophages infecting O157:H7, and Shiga toxin 2 (Stx2)-encoding bacteriophages was studied to determine whether the last persist in the environment more successfully than their host bacteria. The ratios between the numbers of E. coli and those of the different bacteriophages were clearly lower in river water than in sewage of the area, whereas the ratios between the numbers of the different phages were similar. In addition, the numbers of bacteria decreased between 2 and 3 log units in in situ survival experiments performed in river water, whereas the numbers of phages decreased between 1 and 2 log units. Chlorination and pasteurization treatments that reduced by approximately 4 log units the numbers of bacteria reduced by less than 1 log unit the numbers of bacteriophages. Thus, it can be concluded that Stx2-encoding phages persist longer than their host bacteria in the water environment and are more resistant than their host bacteria to chlorination and heat treatment.

Cold Storage and Mild Heat Treatment as Processing Aids to Reduce the Numbers of Vibrio vulnificus in Raw Oysters

1992 ◽  
Vol 55 (12) ◽  
pp. 985-989 ◽  
Author(s):  
DAVID W. COOK ◽  
ANGELA D. RUPLE
Keyword(s):  
Heat Treatment ◽  
Cold Storage ◽  
Similar Pattern ◽  
Vibrio Vulnificus ◽  
Time Dependent ◽  
Naturally Occurring ◽  
Pure Cultures ◽  
Time Required ◽  
And Storage ◽  
Processing Aids

Pure cultures of Vibrio vulnificus held at temperatures of 4 and 0°C underwent a time-dependent decrease in number of recoverable cells. A similar pattern of decreasing numbers was observed with naturally occurring V. vulnificus in cold stored shellstock oysters and shucked oyster meats. The time required for the bacterium to reach undetectable levels (MPN <3/g) may exceed the usual storage life of 14 d for shucked oyster meats and 21 d for shellstock oysters. Freezing and storage of pure cultures of V. vulnificus at −20°C reduced the number of culturable cells more quickly than did holding the cultures at 0°C. However, the organism was cultured from oysters frozen at −20°C for 12 weeks. While cold storage reduced the numbers of V. vulnificus in oysters, such treatment cannot be relied upon to eliminate the organism. Exposure to temperatures above 45°C causes death of V. vulnificus. Decimal reduction times at 47°C for 52 strains averaged 78 s (SD ± 30 s), and D50 values for 18 of the hardiest strains averaged 39.8 s (SD ± 12.2 s). Heating oysters for 10 min in water at 50°C proved adequate to reduce V. vulnificus to a nondetectable level. This treatment does not impart a noticeable cooked appearance or taste to the oysters and may be employed as a strategy to improve the safety of raw oysters.

Effect of the protein, citrate and phosphate content of milk on formation of lactulose during heat treatment

1987 ◽  
Vol 54 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Geoffrey R. Andrews ◽  
S. Krishna Prasad
Keyword(s):  
Heat Treatment ◽  
Milk Protein ◽  
Buffering Capacity ◽  
Phosphate Content ◽  
Mechanism Of Formation ◽  
Amino Groups ◽  
Base Catalysts ◽  
Naturally Occurring ◽  
Heated Milk ◽  
Skimmed Milk

SummaryMilk ultrafiltrate and milks of varying protein, citrate and phosphate concentrations were heated in sealed containers. Protein was found not to be involved in the mechanism of formation of lactulose, but increasing the protein content of milk reduced the concentration of lactulose after heating. This was considered to be due to increased condensation of lactose and lactulose with amino groups of the protein, Less lactulose was formed in milk ultrafiltrate than in skimmed milk accorded the same heat treatment, which was attributed to the buffering capacity of the milk protein in skimmed milk. Activation energies for lactulose formation in skimmed milk and in ultrafiltrate were 128 and 131 kJ/mol respectively. Citrate and phosphate catalysed the formation of lactulose. It is proposed that the formation of free lactulose in heated milk and ultrafiltrate proceeds exclusively by the Lobry de Bruyn-Alberda van Ekenstein transformation with the naturally occurring phosphate and citrate acting as base catalysts.

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