Dose rate Research Papers - Academia.edu (original) (raw)

Presentiamo le tematiche scientifiche e tecnologiche affrontate durante l’irraggiamento di film poliimmide nano-ibridi con una dose di radiazione ultravioletta (UV) pari a 3.000 ore equivalenti di irraggiamento solare fuori dall’atmosfera... more

Presentiamo le tematiche scientifiche e tecnologiche affrontate durante l’irraggiamento di film poliimmide nano-ibridi con una dose di radiazione ultravioletta (UV) pari a 3.000 ore equivalenti di irraggiamento solare fuori dall’atmosfera terrestre, nell’ambito di un test per selezionare il materiale più adatto all’uso come substrato dei second surface mirrors nei telescopi spaziali. In particolare, discutiamo i dettagli relativi al calcolo della dose UV solare, alla taratura dei rivelatori, alla distribuzione spaziale dell’emissione UV della sorgente, all’effetto di ‘guida d’onda’ della camera da vuoto, alla dissipazione del calore in aria, in vuoto e in atmosfera controllata, al controllo remoto continuo (24 ore al giorno) sia della temperatura dei campioni, sia della radiazione della lampada.
In the frame of a Project aiming at selecting substrates for second surface mirrors of space-telescopes, we present the scientific and technological issues addressed during irradiations of nano-hybrid polyimide films deposited on quartz with a ultraviolet (UV) dose of 3,000 space-equivalent Sun hours. In particular, we detail the calculation of the UV dose delivered by Sun, the calibration of the detectors, the spatial distribution of the UV radiation on samples, the remote control 24/24, 7/7 of both samples’ temperature and lamp radiation, the 'equivalent waveguide' effect of the vacuum chamber, the heat dissipation in air, in vacuum and in a helium atmosphere.

The dimension stones sector in Brazil produces several varieties of granites, marbles, slates and basalts. More than half of this production corresponds to around 200 different commercial types of granites with specific names,... more

The dimension stones sector in Brazil produces several varieties of granites, marbles, slates and basalts. More than half of this production corresponds to around 200 different commercial types of granites with specific names, geographical and geological origins and mineral compositions. The well-known natural radioactivity present in rocks, where high radiation levels are associated with igneous rocks such as granite, can

Some pharmacokinetic parameters of selamectin were determined in male (n = 5) and female (n = 5) Beagle dogs following a topical application at a dose rate of 6 mg/kg. The plasma concentration versus time data for the drug were analysed... more

Some pharmacokinetic parameters of selamectin were determined in male (n = 5) and female (n = 5) Beagle dogs following a topical application at a dose rate of 6 mg/kg. The plasma concentration versus time data for the drug were analysed using a one-compartment model. The maximum plasma concentrations of 12.72±5.13 ng/ml for males and 22.65±11.95 ng/ml for females occurred around 5 days after administration. The area under the concentration–time curve (AUC) was 192.08±63.85 ng.day/ml for males and 370.97±146.87 ng.day/ml for females. The mean residence time was the same in males and females (12.55 days). This study reveals a sex-influence on the disposition of selamectin in the plasma of dogs, which implies that further information will be needed for correlation with efficacy studies in dogs.

Coagulation is the most important stage in drinking water treatment processes for the maintenance of acceptable treated water quality and economic plant operation, which involves many complex physical and chemical phenomena. Moreover,... more

Coagulation is the most important stage in drinking water treatment processes for the maintenance of acceptable treated water quality and economic plant operation, which involves many complex physical and chemical phenomena. Moreover, coagulant dosing rate is non-linearly correlated to raw water characteristics such as turbidity, conductivity, pH, temperature, etc. As such, coagulation reaction is hard or even impossible to control satisfactorily by conventional methods. Traditionally, jar tests are used to determine the optimum coagulant dosage. However, this is expensive and time-consuming and does not enable responses to changes in raw water quality in real time. Modelling can be used to overcome these limitations. In this study, an Adaptive Neuro-Fuzzy Inference System (ANFIS) was used for modelling of coagulant dosage in drinking water treatment plant of Boudouaou, Algeria. Six on-line variables of raw water quality including turbidity, conductivity, temperature, dissolved oxygen, ultraviolet absorbance, and the pH of water, and alum dosage were used to build the coagulant dosage model. Two ANFIS-based Neuro-fuzzy systems are presented. The two Neuro-fuzzy systems are: (1) grid partition-based fuzzy inference system (FIS), named ANFIS-GRID, and (2) subtractive clustering based (FIS), named ANFIS-SUB. The low root mean square error and high correlation coefficient values were obtained with ANFIS-SUB method of a first-order Sugeno type inference. This study demonstrates that ANFIS-SUB outperforms ANFIS-GRID due to its simplicity in parameter selection and its fitness in the target problem.

Les applications de l’énergie nucléaire sont diverses dans un grand nombre d’activités comme l’industrie, la médecine,... Parmi les rayonnements utilisés dans le traitement industriel, les rayons gamma trouvent des applications... more

Les applications de l’énergie nucléaire sont diverses dans un grand nombre d’activités comme l’industrie, la médecine,...
Parmi les rayonnements utilisés dans le traitement industriel, les rayons gamma trouvent des applications considérables dans différents domaines. L’étude qualitative de l’effet des rayonnements sur la matière se traduit par la mesure de la dose de rayonnement absorbé ou « dosimétrie » qui est le thème de ce travail. La dosimétrie joue un rôle important dans le contrôle de la qualité de l’irradiation lors de la modification des polymères et le traitement des denrées alimentaires. Cette mesure peut s’effectuer par plusieurs méthodes dosimétriques qu’on peut diviser en deux catégories : la dosimétrie physique et la dosimétrie chimique. Dans ce travail, nous proposons l’étude du dosimètre de Fricke (standard).

Single grain OSL has become a widely used approach in Quaternary geochronology. However, the origins of De distributions and the sources of variation in individual dose estimates are still poorly understood. The amount of scatter in these... more

Single grain OSL has become a widely used approach in Quaternary geochronology. However, the origins of De distributions and the sources of variation in individual dose estimates are still poorly understood. The amount of scatter in these distributions on top of the known uncertainties in measurement and analysis is defined by overdispersion and this quantity is generally used for weighting individual De values to calculate a central equivalent dose. In this study, we address the nature and amount of different sources of dispersion in quartz single grain De estimates, by (i) using appropriate statistical tools to characterize De populations and (ii) modelling, with a specifically designed GEANT4 code, dose rate distributions arising from the presence of potassium feldspar grains in well-sorted sands. The model uses Monte Carlo simulations of beta emissions and interactions in a random close packing of quartz and feldspar spheres representing a sand sample. Based on the simulation results, we explain the discrepancy between intrinsic and natural overdispersion values in a well-bleached sample, thus validating the model. The three parameters having the most influence on dispersion in dose rate distributions, and modelled in this study, appear to be grain size, potassium content and total dose rate.
Finally an analysis of measurement uncertainties and other sources of variations in equivalent dose estimates leads us to conclude that all age models (both logged and unlogged) which include an overdispersion value to weight individual De values rely mainly on unknown parameters; this ignorance may lead to an inadvertent bias in De estimates. Assuming counting statistics make a small contribution to dispersion (as is often the case), we suggest that in some cases it is most appropriate to use unweighted averages of equivalent doses when dividing by commonly measured average dose rates.

Nuclear medicine is a medical specialization that uses radioactive materials injected into the body to diagnose and treat human diseases. The use of different radionuclides and high amounts of radioactive materials makes it necessary for... more

Nuclear medicine is a medical specialization that uses radioactive materials injected into the body to diagnose and treat human diseases. The use of different radionuclides and high amounts of radioactive materials makes it necessary for the facilities where these procedures are conducted to evaluate the corresponding shielding to comply with the design dose limits of a facility and avoid radiological accidents as recommended and accepted in international publications, like the International Commission on Radiological Protection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP). This work compares two methods to calculate the shielding necessary to guarantee que las medicine service zones be safe from ionizing radiations. The first method consists in calculating the transmission factor B to find the thickness of the material necessary to protect the zone of interest, this factor is calculated by bearing in mind the occupancy factors, workloads, use factor, and the design objective dose limit. Upon obtaining the transmission factor B, half value layer (HVL) or tenth value layer (TVL) tables are used for each construction material, obtaining the thickness of the material. The other method is the calculation of is the calculation of rates of exposure through the air Kerma rate constant, then the XCOM databases are used, which were developed by the National Institute of Standards and Technology (NITS) to obtain the attenuation coefficient, used in the law of exponential attenuation; finally, the necessary thickness of the material is obtained to reach the design objective. Finally, the principal differences between both methods are shown and an analysis is performed of the shielding optimization, seeking to set criteria to make recommendations to nuclear medicine services on optimal shielding.. Resumen La medicina nuclear es una especialidad médica que utiliza materiales radioactivos inyectados en el cuerpo para diagnóstico y tratamiento de enfermedades humanas. El uso de diferentes radionúclidos y altas cantidades de materiales radiactivos hace necesario que las instalaciones donde se realicen estos procedimientos evalúen los blindajes correspondientes para cumplir los límites de dosis de diseño de una instalación evitando así accidentes radiológicos recomendados y aceptados en las publicaciones internacionales como el ICRP (International Commision on Radiological Protection) y el NCRP (National Council on Radiation Protection and Measurments). En este trabajo se comparan dos métodos para el cálculo de los blindajes necesarios para garantizar que las zonas del servicio de medicina sean seguras a las radiaciones ionizantes. El primer método consiste en calcular el factor de transmisión B para hallar el espesor del material necesario para proteger la zona de interés, este factor se calcula teniendo en cuenta los factores de ocupación, cargas de trabajo, factor de uso y el límite de dosis objetivo de diseño. Una vez obtenido el factor de transmisión B se usan las tablas de HVL (Half Value Layer) o TVL (Tenth Value Layer) para cada material de construcción obteniéndose el espesor del material. El otro método es el cálculo de las tasas de exposición por medio de la constante de la tasa de Kerma en Aire, luego se usan las bases de datos (XCOM) desarrolladas por NITS (National Institute of Standards and Technology) para obtener el coeficiente de atenuación que son utilizados en la ley exponencial de atenuación; finalmente, se obtiene el espesor de material necesario para alcanzar el objetivo de diseño. Finalmente, se muestran las principales diferencias entre los dos métodos y se hace un análisis de la optimización de los blindajes buscando tener criterios para hacer recomendaciones a los servicios de medicina nuclear sobre blindajes óptimos.

Books and documents attacked by fungi and insects have already been treated by radiation for disinfestations purposes. However, there is still need to investigate the influence of radiation on the cellulose paper structure. The aim of... more

Books and documents attacked by fungi and insects have already been treated by radiation for disinfestations purposes. However, there is still need to investigate the influence of radiation on the cellulose paper structure. The aim of this research was to study the effects of radiation on paper properties, especially those related to strength and appearance. Paper sheets for this study were prepared in the laboratory, using bleached eucalyptus pulp as raw material. No additives were used to concentrate the attention only on the effects of irradiation on the pure cellulose matrix. The samples were irradiated at IPEN's 60Co Gammacell irradiator with six radiation doses, from 3 to 15 kGy at the dose rate 0.817 Gy/s. The properties of paper sheets were tested after irradiation and compared with unirradiated samples according to ISO methods. No significant changes were detected in paper samples irradiated up to 15 kGy.

The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like (238)U, (232)Th, (40)K, and (226)Ra on the territory of Bela Crkva, Serbia.... more

The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like (238)U, (232)Th, (40)K, and (226)Ra on the territory of Bela Crkva, Serbia. Although receiving doses are low from sources like natural radionuclides in soil, because of stochastic effects of ionizing radiation, risk for developing cancer exists and can be quantified. Concentrations of radionuclides from 80 soil samples are measured using HPGe detector. Fatal cancer risk is assessed from calculated ambient dose rate in the target organs of body due to external and internal exposure. Monte Carlo simulations are used to obtain conversion factors which are required to calculate absorbed dose rate in target organs. Assessed cancer risk for (238)U in the case of both inhalation and ingestion exposure is from 1.11 × 10(-6) to 24 × 10(-6) for minimal and maximal activity in soil samples, from 1.02 × 10(-6) to 23.3 × 10(-6) for exposure to (226)Ra, from 1.89 × 10(-6) to 50.3 × 10(-6) for exposure to (232)Th, and from 0.265 × 10(-6) to 9.83 × 10(-6) for exposure to (40)K. Overall risk from (40)K as external and internal source is from 0.8 × 10(-6) to 31.9 × 10(-6). Calculated cancer risks from both inhalation and ingestion exposure could be related to all tissues that are on the way of distribution of particles within the body but especially to deposition sites in the body. Assessed risks for fatal cancer development from inhaled and ingested natural radionuclides originating in soil are not increased.

Urban air quality of industrial cities of Pakistan, namely Gujranwala and Faisalabad was assessed in terms of pollution level indicators such as pollution load index (PLI), geoaccumulation index (Igeo), pollution index (PI) and integrated... more

Urban air quality of industrial cities of Pakistan, namely Gujranwala and Faisalabad was assessed in terms of pollution level indicators such as pollution load index (PLI), geoaccumulation index (Igeo), pollution index (PI) and integrated pollution index (IPI). It was found that both cities have elevated metal concentrations indicating heavy to extreme contamination for most of the sites. Local anthropogenic activities and elevated geoaccumulation indices for different suite of elements were used to indicate possible pollutant sources in these two industrial cities to be traffic derived emissions, suspended soil, road dust, construction materials, fossil fuel and industrial emissions, tanneries, chrome plating units and metal smelters. Comparison of the pollution indices shows that Ba, Br, Ca, Cd, Na, Pb, Sb and Zn have mean PLI, Igeo, PI and IPI for both cities which are in the highly polluted category. Cu, La, Sc, V and Zr have pollution indices corresponding to high or extreme levels in Faisalabad only while Cr and Ti are highly polluting only in Gujranwala. In Faisalabad and Gujranwala it was found that 91.43 % and 85.29 % respectively of the PI data occurs in high level of pollution implying that to some extent Faisalabad is more polluted as compared to Gujranwala.

The uranium mines at Jaduguda and nearby areas of the Singhbhum thrust belt of Jharkhand State are the only operating mines in India, which supply fuel to nuclear power plants. The gamma radiation dose rates observed at different... more

The uranium mines at Jaduguda and nearby areas of the Singhbhum thrust belt of Jharkhand State are the only operating mines in India, which supply fuel to nuclear power plants. The gamma radiation dose rates observed at different locations 1 m above the tailings surface vary from 0.8 to 3.3 μGy h−1. The geometric mean activity concentration of 222Rn in air over the tailings ponds I and II were found to be 30 and 23 Bq m−3, respectively, but reduces to the local background level at the boundaries of the tailings ponds. The uranium and 226Ra levels in the ground water sources in the vicinity of the tailings pond are very similar to the regional average of 3.6 μg L–1 and 23 mBq L−1, respectively, indicating that there is no ground water migration of radioactive material from the tailings pond. This paper gives a brief account of the environmental radioactivity monitoring during uranium mining, ore processing and waste management operations.