Assessment of Exposure Due to Technologically Enhanced Natural Radioactivity in Various Samples of Moroccan Building Materials

The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used in Morocco in order to evaluate the radiological risk caused by natural radioactivity. To this end, the analyses were carried out, using two nuclear techniques, namely high resolution gamma spectrometry and alpha dosimetry based on the use of LR115, on 50 samples collected from large commercial suppliers in Morocco. The results of these analyses show that the average specific activities of 226Ra, 232Th and 40K in these materials vary from 9 to 52 Bq/kg, 3 to 63 Bq/kg and 68 to 705 Bq/kg respectively. These activities remain within the permissible limits of 35 Bq/kg, 30 Bq/kg and 370 Bq/kg respectively, with the exception of a few samples of red brick, gray cement, ceramic and granite. The activity of the radium equivalent (Raeq), the internal (Hin) and external (Hex) hazard indices, the absorbed dose rate, the total annual effective dose , the excess lifetime cancer risk (ELCR) as well as volumic activities, exhalation rates in terms of area (ES) and mass (EM) are calculated for the samples analyzed in this work in order to assess the radiological risks resulting from the use of these materials in various construction activities. It seems that the values of these indices vary from 19 to 196 Bq/kg, 0.08 to 0.67, 0.05 to 0.53, 9 to 91 nGy/h, 0.05 to 0.56 mSv/y, 0.19 × 10−3 to 1.96 × 10−3, 72 to 350 Bq/m3, 56 to 273 mBq⋅m−2⋅h−1 and 3 to 15 mBq⋅kg−1⋅h−1 respectively. The lowest values are identified for gypsum, while the highest are attributed to granite. All of the obtained results of these indices respect the permissible limits except for the Raeq in some granite samples, the ELCR index in all samples except gypsum and the radon volumic activity in some gray cement samples, ceramic and granite. As a result, the different types of building materials analyzed in our work do not present a health risk to the public and can be used in various construction activities, with the exception of a few samples of red brick, gray cement, ceramic and granite. The choice of the use of red brick, gray cement and ceramic should be monitored and adapted according to the criteria of the limitation of the doses whereas the use of the granite must be moderate in order to limit over time the health risk which increases with the duration of exposure of humans to these building materials.

Measurement of Natural Radioactivity and Radon Exhalation Rate in Coal Ash Samples from a Thermal Power Plant

Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that 226Ra activities and 232Th in both ash samples are well above the permissible activity. The values of the external risk index (Hex) and internal one (Hin) for these ashes are below unity, with the exception of 1.28 in fly ash for Hin. The obtained values for the equivalent radium Raeq and annual effective doses Ėin fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq⋅m-2⋅h-1 and 381 mBq⋅m-2⋅h-1, respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn’t have, in any case, a health risk to the public so it can be effectively used in various construction activities.

Experimental and Simulated Effective Dose for Some Building Materials in France

The specific radioactivity of several building materials used in France, which is considered a direct exposure to radiation, has been assessed by γ-ray spectrometry. Corrected for coincidence summing and self-absorption effects, the values for 226Ra, 232Th and 40K were in the ranges 4 - 56, 3 - 72 and 9 - 1136 Bq·kg-1, respectively. The samples were found to have radium-equivalent activities between 5 and 245 Bq·kg-1. Values of 0.02 - 0.67 for the external and 0.03 - 0.82 for the internal hazard indexes were estimated. The calculated absorbed dose in air agrees closely with MCNPX simulations. The conversion of absorbed dose to annual effective dose gave values between 0.03 - 1.09 mSv·y-1. All these values are below action limits recommended by the International Commission on Radiological Protection. The materials examined would not contribute a significant radiation exposure for an occupant and thus are acceptable for construction.

Natural Radioactivity Measurement and Dose Assessment in Soil Samples from Some Selected Areas of Mali

This is the first time that a study applies the gamma ray spectroscopy using a high purity germanium to evaluate the terrestrial gamma radiation level by detector in selected regions of Mali. The results reveal that the activity concentrations of naturally occurring 226Ra, 232Th and 40K radionuclides ranges between respectively 17.26 ±1.81 and 105.43 ±10.36;20.41 ±2.52 and 180.85 ±19.69;41.33 ±8.26 and 627.63 ±85.62 Bq⋅kg−1. The measures of radium equivalent activity (Raeq), absorbed dose rates (ADR), annual effective dose rate (AEDR), external hazard index (Hex), internal hazard index (Hin) and excess lifetime cancer risk (ELCR) were evaluated. Some of the obtained values exceed the recommended safe levels. Further studies are necessary to constitute a baseline reference data about the terrestrial radiation in Mali.

Colloid Thin-Layer Chromatography: A Tool for Gold Sols Validation before Used in Application

Gold nanoparticles have been increasingly used in catalysis, biomedical imaging, biological and chemical sensing, drug delivery, etc. In this study, a straightforward method that allows one to monitor the synthesis of gold sols and their aging, before their fine characterization by sophisticated techniques and before their use is described. Indeed, the “Colloid Thin-Layer Chromatography” method allows one to check the quality of gold colloidal sols during the synthesis. It is also well adapted for monitoring the aging of the sol before the visual observation of its degradation.

Iterative Reconstruction for Transmission Tomography on GPU Using Nvidia CUDA

The iterative reconstruction algorithms for X-ray CT image reconstruction suffer from their high computational cost. Recently Nvidia releases common unified device architecture （CUDA）, allowing developers to access to the processing power of Nvidia graphical processing units （GPUs）, in order to perform general purpose computations. The use of the GPU, as an alternative computation platform, allows decreasing processing times, for parallel algorithms. This paper aims to demonstrate the feasibility of such an implementation for the iterative image reconstruction. The ordered subsets convex （OSC） algorithm, an iterative reconstruction algorithm for transmission tomography, has been developed with CUDA. The performances have been evaluated and compared with another implementation using a single CPU node. The result shows that speed-ups of two orders of magnitude, with a negligible impact on image accuracy, have been observed.

A reference voltage in capacitor–resister hybrid SAR ADC for front-end readout system of CZT detector

An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detec- tor with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors and resistances, which need a large driving ability to deal with the current related to the time and sampling rate. Most of the previous articles about the reference for ADC present only the bandgap part for a low temperature coefficient and high PSRR. However, it is not enough and overall, it needs to consider the output driving ability. The proposed voltage reference is realized by the band-gap reference, voltage generator and output buffer. Apart from a low temperature coefficient and high PSRR, it has the features of a large driving ability and low power con- sumption. What is more, for CZT detectors application in space, a radiation-hardened design has been considered. The measurement results show that the output reference voltage of the buffer is 4.096 V. When the temperature varied from 0 to 80 ℃, the temperature coefficient is 12.2 ppm/℃. The PSRR was -70 dB @ 100 kHz. The drive current of the reference can reach up to 10 mA. The area of the voltage reference in the SAR ADC chip is only 449 × 614μm2. The total power consumption is only 1.092 mW.

Anticancer activity of diterpenes and steroids from Eunicella singularis against two- and three-dimensional breast cancer cell models

Objective: To investigate the anticancer activity of two diterpenes [palmonine F (C1) and palmonine D (C2)] and three steroids [cholesta-5,22-dien-3β-ol (C3), stigmasterol (C4) and 5α-cholest-5-en-3β-ol (C5)], isolated from the Mediterranean gorgonian Eunicella singularis, against MCF-7 breast cancer cell line. Methods: This study was performed on standard monolayer two-dimensional (2D) model to evaluate apoptosis by means of AnnexinV-FITC/PI flow cytometry and on three-dimensional (3D) spheroid model using Celigo imaging cytometer for spheroids size analysis. Results: Results indicated that both diterpenes and steroids exhibited an important apoptotic activity in a concentration-dependent manner with EC50 values of 13, 49, 30, 66 and 65 μg/mL for C1, C2, C3, C4 and C5, respectively. Treatment of MCF-73D cell model with C1–C5 induced growth regression of spheroids in a concentration-dependent manner similar to the clinical anti-breast cancer drug Taxol;over ten days of incubation, growth rates were < 1.5 at Day 10 with all tested compounds at 200 μg/mL. Conclusions: The present study indicates that the two diterpenes C1 and C2 and the three steroids C3, C4 and C5, isolated from Eunicella singularis, might be used as anti-breast cancer candidate drugs for further development.

A longitudinal network analysis of social dynamics in rooks corvus frugilegus： repeated group modifications do not affect social network in captive rooks

Numerous studies have investigated the remarkable variation of social features and the resulting structures across species. Indeed, relationships are dynamic and vary in time according to various factors such as environmental conditions or individuals attributes. However, few studies have investigated the processes that stabilize the structures within a given species, and the behavioral mechanisms that ensure their coherence and continuity across time. Here, we used a dynamic actor-based model, RSiena, to investigate the consistency of the temporal dynamic of relationships of a group of captive rooks facing recurrent modifications in group composition （i.e., the loss and introduction of individuals）. We found that changes in relationships （i.e., formation and removal） followed consistent patterns regardless of group composition and sex-ratio. Rooks preferentially interacted with paired congeners （i.e., unpopular attachment） and were more likely to form rela- tionships with individuals bonded to a current social partner （i.e., ＂friends of friends＂, or triadic closure）. The sex of individuals had no effect on the dynamic of relationships. This robust behav- ioral mechanisms formed the basis of inter-connected networks, composed of sub-structures of in- dividuals emerging from the enmeshment of dyadic and triadic motifs. Overall, the present study reveals crucial aspects of the behavioral mechanisms shaping rooks social structure, suggesting that rooks live in a well-integrated society, going far beyond the unique monogamous pair-bond.

High pt and photon physics with ALICE at LHC

ALICE,A Large Ion Collider Experiment,is dedicated to study the QCD matter at extreme high temperature and density to understand the Quark Gluon Plasma （QGP） and phase transition.High-transversemomentum photons and neutral mesons from the initial hard scattering of partons can be measured with ALICE calorimeters,PHOS （PHOton Spectrometer） and EMCAL （ElectroMagnetic CALorimeter）.Combing the additional central tracking detectors,the γ-jet and π 0-jet measurements thus can be accessed.These measurements offer us a sensitive tomography probe of the hot-dense medium generated in the heavy ion collisions.In this paper,high p T and photon physics is discussed and the ALICE calorimeters capabilities of high-transverse-momentum neutral mesons and γ-jet measurements are presented.

Symposium“How to track wild animals without disturbance and subsequent bias”

Two major steps in field studies of wild animals have been their tagging and,more recently,their instrumen-tation with transmitters and loggers.While the contribution of both to our scientific knowledge is immense,the extent to which the data are reliable and therefore unbi-ased is however generally unknown.Yet,there is now evidence that,even in trained animals,human presence induces a long-lasting stress which is aggravated by capture and handling in order to either attach or recover the instruments,or to take biological samples.Moreover,attached tags and loggers result in a disturbance,partic-ularly for aquatic animals due to the increased drag in water.To determine the relative and overall impact of such disturbances and therefore to select or develop the best possible new instrumentation,it is obviously necessary to get data on undisturbed control animals or at least evaluate the magnitude of the effects of distur-bance on the parameters of interest.