Mechanical stirring: Novel engineering approach for in situ spectroscopic analysis of melt at high temperature.

This paper proposes a novel engineering approach to control molten metals at high temperatures considering the industrial environment of such materials. To reduce analysis time and cost, in-line analysis techniques are more advantageous as they provide real-time information about melt composition. For this reason, recent research works focus on the development of new devices based on LIBS (Laser Induced Breakdown Spectroscopy). These devices allowed for analyzing impurities inside molten metals with great performance. However, improvements related to the immersion probe conception are still required. Indeed, the previous design used bubbling inside the melt, leading to spatial instabilities of the surface analyzed by LIBS. The solution presented here is mechanical stirring by innovative rotary blades which will be a part of an immersion LIBS probe. Their rotation will generate a representative, renewed, and stable surface that will be targeted by spectroscopic techniques in general and particularly by LIBS laser for molten metal monitoring at high temperatures. This solution was validated using experimental tests based on particle imaging velocimetry (PIV) in water at room temperature and then applied to silicon melt at high temperatures. To do so, it was necessary to design a system that allows the introduction of the blade in the melt and controls its rotation.

Assessment of erosion rate in a rainfed agricultural area on the Northwestern coast of Egypt using 137Cs measurements.

In the present work, the use of the fallout radionuclide 137Cs as a tracer for estimating soil redistribution rates over the past 60 years was tested in Egypt at an agricultural field with a smooth slope (0-10%) located in Ras El-Hekma on the Northwestern coast. The average annual soil erosion rate was derived from 137Cs inventories (Bq m-2) and by using the conversion Diffusion and Migration Model (DMM). The activity concentrations of 137Cs with uncertainty ranging between 7.5 and 20.9% were measured using HPGe gamma spectrometry. Approximately exponential shape for the distribution of 137Cs activity concentration was observed within the upper 20 cm of the soil profile associated with the reference site while for the study sites, the 137Cs depth distribution profiles indicate generally an increase of activity reaching a maximum peak of 137Cs usually at a depth of 10-15 cm followed by an abrupt exponential decrease of 137Cs activity concentration with depth. The measured average reference inventory for this area was 697 Bq m-2 with a coefficient of variation of 23%. This value is close to the estimated reference inventory using the conversion model, which was 744 Bq m-2. Transect sampling strategy was adopted at the study area where three parallel transects were chosen based on the common slope. The estimated average annual erosion rate for the three transects was found to be 7.5 t ha-1 y-1, and sediment delivery ratio was approximately 98%, which shows the moderate vulnerability of the Ras El-Hekma area to water erosion.

Assessment of soil erosion rates in a Mediterranean cultivated and uncultivated soils using fallout 137Cs.

Fallout radionuclides, such as 137Cs, have been recognized as a valuable means for studying soil erosion processes. In this study, the 137Cs technique was used to assess soil erosion magnitude and to investigate the effectiveness of terrace cultivations in the High Atlas of Morocco, particularly, the Ourika watershed. 137Cs depth distribution profiles were established along slope gradients associated with land use considering cereal crop, arboriculture and native forests. Along the slope gradient, depth distribution profiles highlight dissimilarities reflecting differences in land use, topographic roughness, soil particle distribution and stoniness. 137Cs inventory decreases exponentially with depth and its penetration increases along the slope. It becomes higher at the bottom of the slope, with penetration reaching 30 cm. 137Cs mass activity and inventory significantly decrease in cultivated terraces, compared to native forest. Although the pattern of 137Cs gain/loss varied according to topography, soil properties and vegetation cover, showing eroding and aggrading profiles, most samples had 137Cs values lower than the reference value, suggesting net-loss of soil as a consequence of erosion processes. The net erosion rates were estimated about 8.5 and 6.0 t ha-1 yr-1 in cereal crop and arboriculture agrosystems, respectively, whereas in the forest, the net erosion rate was lower at about 4.2 t ha-1 yr-1. Soil loss on agricultural terraces is not significantly above tolerable erosion rates for Morocco (<7 t ha-1 yr-1), particularly for arboriculture terraces. A strong correlation was observed between 137Cs and both soil organic carbon and slope gradient, in uncultivated area, whereas, there was no correlation for cultivated terraces. Terraced arboriculture systems should be encouraged for better soil preservation against water erosion in the Ourika watershed.

Radioecological assessment and radiometric dating of sediment cores from dynamic sedimentary systems of Pra and Volta estuaries (Ghana) along the Equatorial Atlantic.

The Volta and Pra estuaries (Ghana, West Africa) are dynamical sedimentary systems whose natural equilibrium is being affected by anthropogenic activities. This paper reports depth-distributions of 210Pb, 226Ra, 234Th, 40K, 228Ra and 137Cs for two sediment cores from these estuaries. Bulk densities were not steady-state and well correlated with 40K (p < 0.00005). Unsupported 210Pb profiles were incomplete, non-monotonic and showed large fluctuations. The assumptions involved in the common 210Pb-based dating models were not meet in these dynamical scenarios, and the use of 137Cs as a time-marker is difficult in Equatorial and South-Hemisphere countries due to its low fallout rates. Chronologies have been solved with the new 210Pb-based TERESA model, which operates with varying but statistically correlated fluxes and sediment accumulation rates (SAR). The core from the Volta reflects the conditions prevailing after the construction of the Akosombo Dam, with a mean SAR of 1.05 ± 0.03 g cm-2·y-1, while a higher value of 2.73 ± 0.06 g cm-2·y-1 was found in the Pra, affected by intense gold mining activities along its course. Radiological and radioecological assessments have been conducted by applying the UNSCEAR protocols and the ERICA model, respectively. The measured radionuclide concentrations do not pose any significant risk for the environment and human health.

Certified Reference Material IAEA-446 for radionuclides in Baltic Sea seaweed.

A Certified Reference Material (CRM) for radionuclides in seaweed (Fucus vesiculosus) from the Baltic Sea (IAEA-446) is described and the results of the certification process are presented. The (40)K, (137)Cs, (234)U and (239+240)Pu radionuclides were certified for this material, and information values for 12 other radionuclides ((90)Sr, (99)Tc, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (230)Th, (232)Th, (235)U, (238)U, (239)Pu and (240)Pu) are presented. The CRM can be used for Quality Assurance/Quality Control of analysis of radionuclides in seaweed and other biota samples, as well as for development and validation of analytical methods, and for training purposes.

Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event.

This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles.

Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex.

In Morocco land degradation - mainly caused by soil erosion - is one of the most serious agroenvironmental threats encountered. However, only limited data are available on the actual magnitude of soil erosion. The study site investigated was an agricultural field located in Marchouch (6°42' W, 33° 47' N) at 68 km south east from Rabat. This work demonstrates the potential of the combined use of (137)Cs, (210)Pb(ex) as radioisotopic soil tracers to estimate mid and long term erosion and deposition rates under Mediterranean agricultural areas. The net soil erosion rates obtained were comparable, 14.3 t ha(-1) yr(-1) and 12.1 ha(-1) yr(-1) for (137)Cs and (210)Pb(ex) respectively, resulting in a similar sediment delivery ratio of about 92%. Soil redistribution patterns of the study field were established using a simple spatialisation approach. The resulting maps generated by the use of both radionuclides were similar, indicating that the soil erosion processes has not changed significantly over the last 100 years. Over the previous 10 year period, the additional results provided by the test of the prediction model RUSLE 2 provided results of the same order of magnitude. Based on the (137)Cs dataset established, the contribution of the tillage erosion impact has been evaluated with the Mass Balance Model 3 and compared to the result obtained with the Mass Balance Model 2. The findings highlighted that water erosion is the leading process in this Moroccan cultivated field, tillage erosion under the experimental condition being the main translocation process within the site without a significant and major impact on the net erosion.

Fallout radionuclide-based techniques for assessing the impact of soil conservation measures on erosion control and soil quality: an overview of the main lessons learnt under an FAO/IAEA Coordinated Research Project.

This paper summarizes key findings and identifies the main lessons learnt from a 5-year (2002-2008) coordinated research project (CRP) on "Assessing the effectiveness of soil conservation measures for sustainable watershed management and crop production using fallout radionuclides" (D1.50.08), organized and funded by the International Atomic Energy Agency through the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. The project brought together nineteen participants, from Australia, Austria, Brazil, Canada, Chile, China, Japan, Morocco, Pakistan, Poland, Romania, Russian Federation, Turkey, United Kingdom, United States of America and Vietnam, involved in the use of nuclear techniques and, more particularly, fallout radionuclides (FRN) to assess the relative impacts of different soil conservation measures on soil erosion and land productivity. The overall objective of the CRP was to develop improved land use and management strategies for sustainable watershed management through effective soil erosion control practices, by the use of ¹³7Cs (half-life of 30.2 years), ²¹°Pb(ex) (half-life of 22.3 years) and 7Be (half-life of 53.4 days) for measuring soil erosion over several spatial and temporal scales. The environmental conditions under which the different research teams applied the tools based on the use of fallout radionuclides varied considerably--a variety of climates, soils, topographies and land uses. Nevertheless, the achievements of the CRP, as reflected in this overview paper, demonstrate that fallout radionuclide-based techniques are powerful tools to assess soil erosion/deposition at several spatial and temporal scales in a wide range of environments, and offer potential to monitor soil quality. The success of the CRP has stimulated an interest in many IAEA Member States in the use of these methodologies to identify factors and practices that can enhance sustainable agriculture and minimize land degradation.

Comparative advantages and limitations of the fallout radionuclides (137)Cs, (210)Pb(ex) and (7)Be for assessing soil erosion and sedimentation.

The fallout radionuclides (FRNs) (137)Cs, (210)Pb(ex) and (7)Be are increasingly being used as a means of obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over a range of different timescales, and they are frequently seen to represent a valuable complement to conventional measurement techniques. The recent development of the (7)Be method has greatly extended the timescale over which FRNs can be used, by permitting assessment of short-term soil erosion linked to individual events and changing soil management practices. This paper aims to review the advantages and limitations of each of the three FRNs and to identify key knowledge gaps linked to their use. In addition, guidelines for selecting the most appropriate FRN and associated approach, in order to deal with a range of spatial and temporal scales and to investigate specific sets of agro-environmental problems, are provided. Key requirements for future work, related to the application of FRNs in soil erosion investigations, are also identified. These include the upscaling of the approach to the catchment scale and a shift from use of the approach as a research tool to a decision support tool.

A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385).

A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides ((40)K, (137)Cs, (226)Ra, (228)Ra, (230)Th, (232)Th, (234)U, (238)U, (238)Pu, (239+240)Pu and (241)Am) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides ((90)Sr, (210)Pb((210)Po), (235)U, (239)Pu, (240)Pu and (241)Pu). Results for less frequently reported radionuclides ((60)Co, (99)Tc, (134)Cs, (155)Eu, (224)Ra and (239)Np) and information on some activity and mass ratios are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical methods and for training purposes.

Partitioning of radiostrontium in marine aqueous suspensions: laboratory experiments and modeling studies.

Quantitative information on the adsorption/desorption of radionuclides by suspended loads is important in the study of their environmental behavior. In this paper, controlled laboratory experiments were directed at studying the kinetic transfer and final distribution of radiostrontium in aqueous suspensions using 85Sr as tracer. The results showed that the uptake of 85Sr in seawater can be properly described by one reversible-reaction model. However, in the absence of competitive cations, it has been shown that two reactions of different characteristic times are unambiguously involved in the kinetic evolution of adsorption. Thus, a modeling approach consisting of three-box model has been applied. The model predicts in a satisfactory way the time evolution of activities in the dissolved phase and two sites in the particles. Experimental evidence showed, through comparison among kinetic and distribution coefficients corresponding to different conditions, that Ca2+ affects strongly the rate and extent of Sr uptake by suspended particles. On the other hand, distribution coefficients were found to be sensitive to changes in suspended particulate matter (SPM) concentration, exhibiting a reverse effect with this parameter on the adsorption. In addition, desorption from particles is important showing that Sr can be easily released due to cation-exchange processes.

Certified reference material for radionuclides in fish flesh sample IAEA-414 (mixed fish from the Irish Sea and North Sea).

A certified reference material (CRM) for radionuclides in fish sample IAEA-414 (mixed fish from the Irish Sea and North Seas) is described and the results of the certification process are presented. Nine radionuclides (40K, 137Cs, 232Th, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) were certified for this material. Information on massic activities with 95% confidence intervals is given for six other radionuclides (90Sr, 210Pb(210Po), 226Ra, 239Pu, 240Pu 241Pu). Less frequently reported radionuclides (99Tc, 129I, 228Th, 230Th and 237Np) and information on some activity and mass ratios are also included. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in fish sample, for the development and validation of analytical methods and for training purposes. The material is available from IAEA, Vienna, in 100 g units.

Use of (137)Cs technique for soil erosion study in the agricultural region of Casablanca in Morocco.

Accelerated erosion and soil degradation currently cause serious problems to the Oued El Maleh basin (Morocco). Furthermore, there is still only limited information on rates of soil loss for optimising strategies for soil conservation. In the present study we have used the (137)Cs technique to assess the soil erosion rates on an agricultural land in Oued el Maleh basin near Casablanca (Morocco). A small representative agricultural field was selected to investigate the soil degradation required by soil managers in this region. The transect approach was applied for sampling to identify the spatial redistribution of (137)Cs. The spatial variability of (137)Cs inventory has provided evidence of the importance of tillage process and the human effects on the redistribution of (137)Cs. The mean (137)Cs inventory was found about 842 Bq m(-2), this value corresponds to an erosion rate of 82 tha(-1) yr(-1) by applying simplified mass balance model in a preliminary estimation. When data on site characteristics were available, the refined mass balance model was applied to highlight the contribution of tillage effect in soil redistribution. The erosion rate was estimated about 50 tha(-1) yr(-1). The aspects related to the sampling procedures and the models for calculation of erosion rates are discussed.

Direct identification of human oxytocin receptor-binding domains using a photoactivatable cyclic peptide antagonist: comparison with the human V1a vasopressin receptor.

Understanding of the molecular determinants responsible for antagonist binding to the oxytocin receptor should provide important insights that facilitate rational design of potential therapeutic agents for the treatment of preterm labor. To study ligand/receptor interactions, we used a novel photosensitive radioiodinated antagonist of the human oxytocin receptor, d(CH(2))(5) [Tyr(Me)(2),Thr(4),Orn(8),Phe(3(125)I,4N(3))-NH(2)9]vasotocin. This ligand had an equivalent high affinity for human oxytocin and V(1a) vasopressin receptors expressed in Chinese hamster ovary cells. Taking advantage of this dual specificity, we conducted photoaffinity labeling experiments on both receptors. Photolabeled oxytocin and V(1a) receptors appeared as a unique protein band at 70-75 kDa and two labeled protein bands at 85-90 and 46 kDa, respectively. To identify contact sites between the antagonist and the receptors, the labeled 70-75- and the 46-kDa proteins were cleaved with CNBr and digested with Lys-C and Arg-C endoproteinases. The fragmentation patterns allowed the identification of a covalently labeled region in the oxytocin receptor transmembrane domain III consisting of the residues Leu(114)-Val(115)-Lys(116). Analysis of contact sites in the V(1a) receptor led to the identification of the homologous region consisting of the residues Val(126)-Val(127)-Lys(128). Binding domains were confirmed by mutation of several CNBr cleavage sites in the oxytocin receptor and of one Lys-C cleavage site in the V(1a) receptor. The results are in agreement with previous experimental data and three-dimensional models of agonist and antagonist binding to members of the oxytocin/vasopressin receptor family.

Natural radioactivity in phosphates, phosphogypsum and natural waters in Morocco.

The contents of natural radionuclides (uranium, actinium and thorium series) were measured in sedimentary phosphate rock samples using high-resolution gamma spectrometry. Data obtained for uranium content (ppm) were compared with the results obtained by a method based on the measurements using solid-state nuclear track detectors (SSNTD) in the same samples. The potential leaching of radionuclides from sedimentary phosphate rock during the industrial production of the phosphoric acid was studied. The process of leaching of the radioisotopes from phosphogypsum was discussed. A method for the direct alpha counting of 226Ra thin source, elaborated by the deposition of Ra from aqueous solutions on manganese oxides film deposited on polyvinyl support, have been developed and applied for the determination of 226Ra in natural water samples. The results show that only the water sample from the mine area reveals the presence of 226Ra at a level of about 0.2 Bq l-1.

[Associated fracture of the posteromedial tubercle and the lateral process of the talus: a case report. Contribution of computed tomography]. / Fracture associée du tubercule postéro-médial et de l'apophyse latérale de l'astragale: un cas. Apport de la tomodensitométrie.

PURPOSE OF THE STUDY: Fracture of lateral process of the talus is an uncommon injury, fracture of the posteromedial tubercle of the talus is quite rare, and association of the two lesions is not reported previously. We report a case of an associated fracture of posteromedial tubercle an lateral process of the talus. PATIENT AND METHODS: The mechanism of injury was forced ankle dorsiflexion and pronation, this mechanism was responsible of an avulsion of the posteromedial tubercle by the postero talotibial ligament and a fracture of lateral process by compression between the lateral malleolus and the calcaneus. RESULTS: Conventional radiographs permitted the diagnosis of the lateral process fracture but the fracture of the posteromedial tubercle was showed only on CT scans. DISCUSSION: The fracture of the posteromedial tubercle was treated by internal fixation, through a posteromedial approach. At 12 months follow-up the patient was able to walk without pain and radiographic result was excellent (no avascular necrosis of the tubercle and no Arthrosis of subtalar joint).

[Elastic intramedullary nailing of the tibia with the Marchetti-Vicenzi nail. 43 treated cases]. / L'enclouage élastique du tibia à foyer fermé par clou de Marchetti-Vicenzi. A propos de 43 cas traités.

PURPOSE OF THE STUDY: The purpose of this study was to analyse the results of tibial intramedullary nailing using an unreamed "Universal Elastic Bundle Nail". MATERIAL AND METHODS: Forty-three intramedullary nailing of tibial shaft were done in 43 patients with recents fractures, from May 1993 and May 1996. There were 36 males and 7 females. The average age was 31.5 years (range 17-68 years). Thirty-three were injured in a traffic accident (20 motorcycles, 5 pedestrians and 8 car passengers), seven were injured in a home accident (fall) and three had a sport injury. There were 13 open fractures according to Gustilo: 5 grade I, 7 grade II and one grade III B. Eight fractures involved the proximal metaphyseal part of the tibia, 16 the distal metaphyseal part and 14 the tibial shaft; in five cases there were segmental fractures. According to AO classification there were: 10 fractures type A, 24 fractures type B and 9 fractures type C (5 segmental fractures). In 5 cases there were associated femoral fractures: three ipsilaterals and two controlaterals. All were treated in the same time: four by UEBN device and one by AO's nail. All the patients with type B and C fractures were positioned on a Maquet table with a boot traction or transcalcaneal pin traction (in the distal fractures). The nail was introduced after closed reduction through a vertical transpatellar tendon incision, without reaming procedure. RESULTS: Forty one fractures healed after an average time of 96 days (60-120). In 11 open fractures bone union occurred after 98 days (85-120). The distal fractures healed after a mean time of 86 days (60-120), proximal fractures in 123 days and mid shaft fractures in 98 days. In type A fractures bone union occurred after an average time of 68 days, while bone union occurred after a mean time of 100 days in type B and C fractures. Two patients with an open proximal type B fracture, had a delayed union: both healed after proximal screws removal. Two fractures healed with a valgus angulaton 5 degrees and 10 degrees. No infection, no loss of reduction and no bundle migration has been noted. DISCUSSION: The Marchetti-Vicenzi's nail (UEBN) permitted a stable fixation in tibial fractures. The use of this unreamed nailing coupled with an automatic distal locking in the metaphyseal cancellous bone, reduced operative time and shortened X Ray's radiation exposure. At the follow-up fracture healing occurred in 41 cases 95.3 p. 100 at four months. Two delayed union occurred after four months, the two cases were open fractures grade II. All the two cases healed after secondary procedure without any loss of function. Malunion occurred in two patients (in only one case there was a major valgus angulation 10 degrees), the two cases were related to technical error. We had no cases of infection or leg shortening or bundle migration in the ankle joint. CONCLUSION: We believe that Universal Elastic Bundle Nail allows a stable and safety fixation in open or closed tibial fractures without pseudarthrosis and without infection (in our series).

PLD score evaluation of the quality of life after severe (Grade III) open tibial fractures

Grade III open tibial fractures often require long hospitialized and many operations. They always leave unsightly scars and functional results are sometimes very poor. We wanted to establish a predictive score for use in all cases to help us to decide if amputation would give a better result or not. We devised a "PLD" scoring system with a maximum of twenty points, comprising data that concern the patient (0 to 4), the lesions (0 to 14) and the delay of bone coverage(0 to 2). Patient outcome was quantitatively scored by assessing the function (15 points) and the quality of life (professional, sport and leisure, social and psychologic, 15 points). Twenty-seven cases of grade III open tibial fracture were reviewed for this study. Traffic accidents (23 cases) were very frequent. For each case, the total hospital stay and the type and the number of interventions were noted. PLD scores were calculated at emergency and after one month. Final outcome was evaluated at the latest patients follow-up. Results showed that if the PLD score in emergency or at one month was < 5, the final resut was good or excellent (>25) for more than 80 percent of patients. If the score at one month was < 5, the result was judged poor (<20) in more than half the cases. If the PLD score in emergency or at one month was o 20, all such cases required an amputation in emergency or at a later stage. (AU)