Water activity and freezing points in aqueous solutions of manganese nitrate: experimental and modeling

The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol-kg-1.This work was developed in the scope of the projects POCI-01-0145-FEDER- 006984—Associate Laboratory LSRE-LCM both funded by European Regional Development Fund (ERDF) through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia. This work is also a result of project ‘‘AIProcMat@N2020—Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020’’, with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through ERDF.info:eu-repo/semantics/publishedVersio

Validação da bioimpedância elétrica por multifrequência em atletas

É reconhecida a importância de avaliar a composição corporal na população atlética. Para o efeito é preciso utilizar técnicas válidas na determinação dos principais componentes moleculares. A Densitometria Radiológica de Dupla Energia (DXA) é um método preciso e válido para avaliação de composição corporal. No entanto, a DXA é uma técnica ainda pouco acessível em contextos não laboratoriais. Desta forma, é importante utilizar técnicas mais simples e práticas como a bioimpedância eléctrica (BIA). No entanto poucos estudos validaram a BIA especialmente de multifrequência na avaliação da composição corporal em atletas. Assim, o objetivo desta investigação é testar a validade da BIA de multifrequência (Tanita, modelo MC-180) na determinação do conteúdo mineral ósseo (CMO), massa gorda (MG) e massa isenta de gordura e osso (MIGO) em atletas. Um total de 79 atletas (35 homens) foram avaliados pela BIA e pela DXA. Comparação de médias, coeficiente de correlação de concordância, regressão múltipla, e o método Bland-Altman foram realizados. A Tanita apresentou um poder explicativo de 76 %, 72%, 95% e 73% da variabilidade total observada a partir do método de referência para a MG (kg), MG (%), MIGO e CMO, respectivamente. O coeficiente de correlação de concordância para a MIGO apresentou uma força de concordância substancial de 0.927. Observaram-se limites de concordância relativamente elevados na estimativa dos vários componentes corporais. Em conclusão, a Tanita MC-180 é uma alternativa válida especialmente na estimação da massa isenta de gordura e de osso, num grupo de atletas. Contudo, devido aos limites de concordância obtidos na determinação das vários componentes este equipamento apresenta uma validade limitada na estimação individual da composição corporal. Palavras-chave: Atleta; Avaliação Física; Composição Corporal.It is recognized the importance of assessing body composition in athletic populations. Therefore, it is necessary to use valid techniques for the determination of the main molecular components. Dual-energy X-ray absorptiometry (DXA) is a precise and valid method for assessing body composition. However, DXA is still not available at the clinical and field settings. Thus, it is important to use simple techniques such as electrical bioimpedance analysis (BIA) but few studies validated this technique specifically multifrequency BIA in body composition assessment in athletes. Therefore, the aim of this research is to test the validity of multifrequency BIA (Tanita, Model MC-180) in the determination of bone mineral content (BMC), lean soft tissue (LST) and fat mass (FM) in athletes. A total of 79 elite athletes (35 males) were assessed by DXA and BIA. Comparison of means, concordance coefficient correlation, multiple regression and Bland-Altman analysis were performed. Tanita explained 76%, 72%, 95% and 73% of the total variability observed from the reference method for FM (kg), FM (%), LST and BMC, respectively. The concordance coefficient correlation for MIGO presented a substantial strength of agreement of 0,927. However, relatively larger limits of agreement were found between BIA and DXA for the several body components. These findings reveal that the Tanita MC-180 is a valid alternative, particularly in the estimation of LST, in a group of athletes. However, due to the limits of agreement obtained in the determination of the body components this equipment presents a more limited validity in the estimation of individual body composition. Key Words: Athletes; Physical Assessment; Body Composition

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Development of the irradiation facility SIBO INRA/Tangier, Morocco by upgrading cobalt-60 in a temporary pool and enhancing safety and control features

An automatic control system is one of the most important parts of an irradiation facility. The level of this control is always maintained to comply with safety procedures during routine work in this field. Also sometimes it is limited to the minimum level of regulation required due to economical aspects; some commercial systems are generally made by manufacturers of industrial facilities and considered affordable by irradiators. In some cases specific irradiation facilities tailor their control systems to their needs. For this kind of irradiator the control system can be developed and upgraded according to personal and industrial experiences. These upgrading procedures are also used by others to develop their systems. The objective of this paper is to share a local experience in upgrading security, safety systems and the use of cobalt-60 for the irradiator. It is a composite experiment at SIBO INRA/Tangier, Morocco and concerns the: (i) upgrade of cobalt-60 in a temporary pool in the SIBO irradiator in Tangier. This operation was conducted in collaboration with the International Atomic Energy Agency (IAEA) and was a success story of 2014 according to the general conference of IAEA; (ii) safety and technical upgrade of the system in the SIBO irradiator made in collaboration with IAEA; (iii) installation and upgrade of the security system in accordance with the Global Threat Reduction Programme (GTRP) to reduce the threat of a Radiological Dispersal Device (RDD) in collaboration with The United States Department of Energy’s National Nuclear Security Administration (NNSA)

Analytical and Approximate Solutions of the Nonlinear Gas Dynamic Equation Using a Hybrid Approach

This paper presents the study of a numerical scheme for the analytical solution of nonlinear gas dynamic equation. We use the idea of Laplace–Carson transform and associate it with the homotopy perturbation method (HPM) for obtaining the series solution of the equation. We show that this hybrid approach is excellent in agreement and converges to the exact solution very smoothly. Further, HPM combined with He’s polynomial is utilized to minimize the numerical simulations in nonlinear conditions that make it easy for the implementation of Laplace–Carson transform. We also exhibit a few graphical solutions to indicate that this approach is extremely reliable and convenient for linear and nonlinear challenges

Evaluation of chemical composition available by-products in the North of Morocco

peer reviewe

Comportement mécanique du béton dégradé à l'échelle de l'interface ciment-granulats

International audienceCet article présente une étude expérimentale portant sur la lixiviation du béton à l'échelle de l'interface ciment-granulats, et ses conséquences sur le comportement du béton à cette échelle. Un protocole expérimental a été mis au point pour étudier les effets du mécanismes de lixiviation de calcium au niveau de la zone de transition interfaciale (ITZ) sur les propriétés mécaniques du béton. Compte tenu du temps caractéristique long du phénomène de lixiviation, l'étude expérimentale au laboratoire est accélérée par l'utilisation d'une solution de nitrate d'ammonium. Afin de mesurer le développement et la cinétique de dégradation au niveau de la liaison cimentée, et en particulier à l'interface ciment-granulats, les fronts de lixiviation du béton sont caractérisés pour des temps données en utilisant la phénolphtaléine.Des essais mécaniques locaux (compression et traction) sont réalisés sur des échantillons sains et des échantillons dégradés chimiquement. Les résultats permettent de corréler l'avancement de la lixiviation à l'évolution des propriétés mécaniques à l'échelle locale considérée