Physic

Radiometric study of natural radioactivity from soil has been carried out to estimate the concentration of gamma-induced radioisotopes and their associated radiological risk in two sampling sites, an uncultivated (undisturbed) and an agricultural site located near an industrial zone. A High Purity Germanium (HPG) detector was used to measure natural gamma emitting radionuclides of 40 K, 232 Th and 226 Ra. With a portable X-ray fluorescence equipment, elemental concentration of several major elements (Ca, Fe, Ti and K) and minor element (Mn, Zn, As, Zr, P, Cu, Cr and Ni) were measured. The assessment of soil contamination was made by determining the geoaccumulation index, the enrichment factor, the contamination factor and the pollution load index of the various metals targeted in this study. The results indicate moderate soil pollution at the Bargny site by heavy metal As. But also, that this same soil of the Bargny study site was significantly enriched with arsenic and chromium. Levels of radiological hazard indices associated with the measured radioisotopes were inferred. The average of the radium equivalent activity calculated is 65.76 ±3.40 Bq.Kg -1 (disturbed) and 57.25 ± 5.76 (undisturbed); while the mean of the total absorbed gamma dose rate was 30.20±1.56nGy.h -1 (disturbed), and 26.64 ± 2.67 (undisturbed). The External hazard ranged between 0.17 and 0.19 in the disturbed sampling site and 0.12 and 0.17 (Undisturbed).

The most used QuEChERS and gas chromatography methods were performed, to evaluate the presence of organochlorines, organophosphate, polychlorinated biphenyl and chlorobenzenes in water and in fish. According to the standard ISO IEC 17025, a recovery rate obtained ranged from 70 to 120% assessing the reliability of analysis results. The exceed rate in fish of Malathion is 22.2, and 5.2 ppm in sampling site XGL411 and XGL416 respectively, Endrin is 4 ppm in XGL415, Trifluralin and Parathion is 1.6, 1.4, 1.8 and 4.2 ppm in XGL413, XGL414, XGL415 and XGL417 respectively and Pyrimiphos-Methyl is 1ppm in XGL417. In water, the exceed rate of Trifluralin is 6.5ppb in XGL411 and Parathion and Pyrimiphos methyl is 1.1, 1.8, 1, 1, 1.5 ppb in XGL412, XGL413, XGL414, XGL415 and XGL420 respectively. The purpose of this work is to assess a chemical analysis related to screening pesticides and potentially toxic metal in water and fish samples taken from Guiers Lake. The estimating level of contamin...

After an extensional stage giving rise to tholeiitic basalts and gabbros, the south western part of Kédougou Kéniéba Inlier (KKI) was affected by three phases of compressionnal deformation. The first phase (D1) was related to NE-SW stress that led to northeastward thrusting. Early granitoids would be implemented during this tectonic event. The second phase (D2) was due to East-West compressional stress that created combined strike sleep faults: NNW-SSE and NNE-SSW respectively sinistral and dextral. During this phase, some volcanic rocks and gabbros were mylonitized, hydrothermalized and transformed into quartzites. These quartzites were considered as sedimentary rocks in previous studies. Granitic plutons and andesites took place during this tectonic phase. D3 deformation occurred towards the end of the Eburnean orogeny. It would be held in two episodes. In the first episode, WNW-ESE stresses created conjugate shears: sinistral NNW-SSE and dextral NE-SW. In the second episode, stresses moved toward the NE-SW direction and made the resulting brittle structures arranged in NS dextral corridors.

Attack by bacteria can induce structural changes in teeth. The aim of this study was to assess the spectra and the densities of mineralized dental tissue chemical components during cariogenic and periodontal pathologies in a population of Senegalese individuals. Studies using in vitro laser spectroscopy or laser induced breakdown spectroscopy (LIBS) of teeth extracted from selected patients in a hospital have allowed various chemical constituents to be observed. Alterations in these constituents provide an indication of physiological changes in the hard dental tissues which could be affected by caries or by periodontal disease. Hence, LIBS represents a powerful tool to detect dental constituents and for the prevention and biological monitoring.

We present the results from four stellar occultations by (486958) Arrokoth, the flyby target of the New Horizons extended mission. Three of the four efforts led to positive detections of the body, and all constrained the presence of rings and other debris, finding none. Twenty-five mobile stations were deployed for 2017 June 3 and augmented by fixed telescopes. There were no positive detections from this effort. The event on 2017 July 10 was observed by the Stratospheric Observatory for Infrared Astronomy with one very short chord. Twenty-four deployed stations on 2017 July 17 resulted in five chords that clearly showed a complicated shape consistent with a contact binary with rough dimensions of 20 by 30 km for the overall outline. A visible albedo of 10% was derived from these data. Twenty-two systems were deployed for the fourth event on 2018 August 4 and resulted in two chords. The combination of the occultation data and the flyby results provides a significant refinement of the rotation period, now estimated to be 15.9380±0.0005 hr. The occultation data also provided high-precision astrometric constraints on the position of the object that were crucial for supporting the navigation for the New Horizons flyby. This work demonstrates an effective method for obtaining detailed size and shape information and probing for rings and dust on distant Kuiper Belt objects as well as being an important source of positional data that can aid in spacecraft navigation that is particularly useful for small and distant bodies.

The motivation of the diagonalization method is to take into consideration the coupling between closed and opened channels in term of perturbation theory and to neglect the indirect coupling as well but also the autoionisation states through the opened channels. This procedure leads to a relatively simple mathematical problem consisting of solving a system of linear algebraic equations instead of a system of coupled differential equations or integro-differential equations. Diagonalization method under LS coupling scheme for the states 1

New environmental challenges and research opportunities arise on the use of solid wastes as well as their basic properties. In fact, recycling of these wastes and their by-products is attracting increasing interest worldwide because of the high environmental impact in the cement, concrete and other industries. Two types (type1: Fa100 and type 2: Ba100) of sludge ashes from the sludge waste center of Camberene (Senegal) were combined with different proportions of lime to assess their potential use in civil engineering. XRF, optical microscopy and spectroscopy were used to characterize the samples. The following major elements are present in the ashes: SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, P 2 O 5. For the minor elements their concentration are very important in type 1 compared to those in type 2. These ashes have similar composition with cement except for CaO. The measurement of absorbance on the ashes shows a clear difference in optical absorption between samples. The lime pellet transmits more compared to Ba100 and Fa100 pellets. The materials obtained by mixing ash with lime in various proportions have a lower optical transmission with respect to lime and ash taken separately. Thus, the designed materials transmit less light which suggests an improved thermal isolation. The studied ashes suggest that they are not dangerous based on the Annex III of (criterion H14 of Directive 91 / 689 / EEC).

We report in this paper energy positions of the 2P˚_2s 2 2p 2 (1 D)nd 2 P, 2P˚_2s 2 2p 2 (1 D)nd 2 S, 2P˚_2s 2 2p 2 (1 D)ns 2 D, 2P˚_2s 2 2p 2 (1 S)nd 2 D, and 2P˚_2s 2 2p 3 (3 P)np 2 D Rydberg series in the photoionization spectra originating from 2P˚ metastable state of O+ ions. Calculations are performed up to n = 30 using the Modified Orbital Atomic Theory (MAOT). The present results are compared to the experimental data of Aguilar which are the only available values. The accurate data presented in this work may be a useful guideline for future experimental and other theoretical studies.

In this study, the activity concentrations of 226 Ra, 232 Th and 40 K in twenty cement samples of four types (CEM, CEM II, CEM III, and CEM IV) collected from building material suppliers in Senegal were measured using a low-background digital gamma-ray spectrometer equipped with broad energy germanium detector. The activity concentrations of 226 Ra, 232 Th and 40 K varied from 7.1-150.3 Bq kg −1 , 3.7-16.1 Bq kg −1 , and 48.7-133.9 Bq kg −1 , respectively. Also, possible radiological risks from the usage of these materials were assessed by estimating external and internal index, indoor absorbed gamma dose rate and the corresponding annual effective dose, effective dose rate to different body organs and tissus, and excess lifetime cancer risk. The estimated radiological hazard indices were revised in light of the relevant national and international legislation and guidance. The values of the radiological hazard indices were found to be within relevant all limit values for structural building materials.

Calculations of the energy levels of atoms and ions with Z ≤ 10 are carried out in this paper using the variational method. New wave function with two terms including correlation was performed to calculate excited (ns 2 ) 1 Se, (np 2 ) 1 D e , (nd 2 ) 1 G e , (nf 2 ) 1 I e , (nh 2 ) 1 M e and (ng 2 ) 1 K e states with (n ≤ 7). The results obtained show quantitatively the great significance of electron correlation effects in the doubly excited states. These results are in compliance with some experimental and theoretical data.

In this paper, we calculate energies for 2 s 3 s +1,3 S e , 2 s 4 s +1,3 S e , 2 snp +1,3 P 0 with n≤6 and 2 p 3 p +1,3 D e , 2 p 4 p +1,3 D e autoionizing states of helium-like ions. These calculations are investigated using a new wave function correlated to four terms. Total energies calculations are performed between two electrons in He-isoelectronic series up to Z = 10, base on the Screening Constant by Unit Nuclear charge method in the framework of a variational procedure. The results obtained are in compliance with recent theoretical calculations.

Recycling of wastes and their by-products is attracting increasing interest worldwide because of the high environmental impact in the cement, concrete and other industries. This work deals with the study of the physico-chemical characteristics of binders based on sewage sludge ashes and lime. In a first step, we used X-ray fluorescence to determine the chemical composition of ash, lime and binders. This allowed us to see that the chemical composition of sewage sludge ash is similar to that of cement. We then used X-ray diffraction to identify the main mineralogical phases in the samples. Compressive strengths of mortars containing 20%, 40%, 60% and 80% of SSA showed that SSA has a long-term positive effect which might be related to a slight pozzolanic activity. The L 4 binder consisting of 80% fine ash and 20% lime has a higher compressive strength than the others. The binder setting start time is greater than that of cement but shorter than that of lime. The study of the thermophysical properties of the L 4 binder shows that it has a higher thermal resistance than cement and clay mortars. Moreover, it heats up less quickly because of its low effusivity compared to the latter two. This analysis highlighted the principal characteristics that must be taken into account to use SSA correctly in lime-based materials.

Solid wastes and their by-products are gaining interest worldwide given their high environmental impact. Fly ash and Bottom ash from Camberene sludge waste center (Senegal) were characterized to assess the heavy metal contamination (using XRF and the Toxicological Risk) that is very important in type 1 unlike in type 2. The Index of geo-accumulation (Igeo), the Pollution load index (PLI), the Enrichment factor (EF) and Contamination factor (CF) have been computed to evaluate the contamination rate. These show that the fly ash has aIgeo value of 3.57 for Pb and 3.04 for As which means they are very polluted. For Cu we have an Igeo value of 4.23 and for Zn it is 4.67 so these ashes are strongly to extremely polluted by Cu and Zn but unpolluted to moderately polluted by Cr. For the bottom ashes we have Igeo values of 3.03 for Cu and 3.02 for Zn, to say they are also strongly polluted. However, they are not polluted by Cr and are only moderately polluted by Pb and As results confirmed b...

Discrimination of tea varieties from different countries is demanding task and to address this requirement, we demonstrate the feasibility of using x-ray fluorescence (XRF) spectrometry combined with chemometric, to classify geographical origin of different based on their elemental contents. Both direct non-pre-treatment XRF spectra and elemental concentration were used to achieve discrimination of tea. The classification was carried out on the basis of chemical information contained in tea samples. In total, 13 elements (Mg,

Identifying the particulate matter (PM) sources is an essential step to assess PM effects on human health and understand PM’s behavior in a specific environment. Information about the composition of the organic or/and inorganic fraction of PM is usually used for source apportionment studies. In this study that took place in Dakar, Senegal, the identification of the sources of two PM fractions was performed by utilizing data on the elemental composition and elemental carbon content. Four PM sources were identified using positive matrix factorization (PMF): Industrial emissions, mineral dust, traffic emissions, and sea salt/secondary sulfates. To assess the effect of PM on human health the air quality index (AQI) was estimated. The highest values of AQI are approximately 497 and 488, in Yoff and Hlm, respectively. The spatial location of the sources was investigated using potential source contribution function (PSCF). PSCF plots revealed the high effect of transported dust from the de...