Experimental Investigation on the Properties of a Recycled Aggregate Concrete Based on Waste of the Industrial Mineral Additions

This study investigates the possible effects of incorporating different industry wastes during manufacturing of concrete, with percentages ranging from 0% to 30%, and assesses the influence of these combinations (mineral additions and recycled aggregates) on the properties of a recycled concrete comprised of these two main constituents products. Recycled concrete samples with different combinations of mineral additions at various dosages were used to determine these properties in the fresh and hardened states. The ”Design-expert” methodology was used to analyse the results after 7, 14 and 28 days, identifying correlations and the effects of the different variables. The results obtained showed the advantageous effect of incorporating the pozzolana and slag into the concrete mixture at dosages of 15% and 30%, they also demonstrated the low optimal percentage of marble fillers of 5%. These findings suggest that replacing clinker with industrial waste could limit the dust and CO2 emissions into the atmosphere during concrete manufacture, offering environmental advantages as well as conserving the natural resources of aggregate recovery from C&D wastes. Keywords: environmental concrete, mineral additions, recycled aggregate, design expert method

A Sensitive Micro Conductometric Ethanol Sensor Based on an Alcohol Dehydrogenase-Gold Nanoparticle Chitosan Composite

In this paper, a microconductometric sensor has been designed, based on a chitosan composite including alcohol dehydrogenase—and its cofactor—and gold nanoparticles, and was calibrated by differential measurements in the headspace of aqueous solutions of ethanol. The role of gold nanoparticles (GNPs) was crucial in improving the analytical performance of the ethanol sensor in terms of response time, sensitivity, selectivity, and reproducibility. The response time was reduced to 10 s, compared to 21 s without GNPs. The sensitivity was 416 µS/cm (v/v%)−1 which is 11.3 times higher than without GNPs. The selectivity factor versus methanol was 8.3, three times higher than without GNPs. The relative standard deviation (RSD) obtained with the same sensor was 2%, whereas it was found to be 12% without GNPs. When the air from the operator’s mouth was analyzed just after rinsing with an antiseptic mouthwash, the ethanol content was very high (3.5 v/v%). The background level was reached only after rinsing with water

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

Contribution à la compréhension des phénomènes de dissipation d\u27énergie dans les céramiques piézo-électriques de type PZT : Effets du dopage au potassium et au niobium.

Ce travail a été consacré principalement à la compréhension des mécanismes responsables des dissipations d\u27énergie dans les matériaux piézo-électriques de zircono titanate de plomb -PZT. Les compositions élaborées sont des zircono titanate de plomb dans la zone morphotropique et répondant à une formulation chimique de type : Pb (Zr1-x Tix)O3 et présentant un rapport Zr/Ti de 0.54/0.46, non dopées (PZT 54/46), dopées au potassium à 0.5% atomique respectivement (PKZT 0.5/24/46 et PKZT 1/54/46), et dopées au niobium à 1%atomique respectivement (PNZT 1/54/46 et PNZT 2/54/46). L\u27utilisation de la spectrométrie mécanique comme technique principale d\u27investigation nous a permis la mise en évidence de deux pics de transition de phase P1 et P2, et de deux autres pics de pertes mécaniques R1 et R2Le pic P1 correspond à la transition de Curie entre la phase para électrique et la phase ferroélectrique quadratique. Le pic P2 représente les pertes associées à la transmission morphotropique entre les phases ferroélectriques quadratique et rhomboédrique. Le pic R2 est contrôlé par un mécanisme de relaxation dû à des interactions simples formant des dipôles élastiques/diélectriques anisotropes entre les lacunes d\u27oxygène et les lacunes cationiques. Le pic R1 est la superposition de deux pics : L\u27un est lié au mouvement visqueux des parois de domaines ferroélectriques et à l\u27évolution de la structure des domaines ferroélectriques, causé par la nucléation de nouveaux domaines, Et l\u27autre est contrôlé par l\u27interaction des parois de domaines avec un nuage de défauts ponctuel environnant, et à l\u27opposition de ces derniers (lacunes cationiques et/ou au complexes de défauts) au mouvement des parois des domaines ferroélectriques

Contribution à la compréhension des phénomènes de dissipation d'énergie dans les céramiques piézo-électriques de type PZT (effets du dopage au potassium et au niobium)

Ce travail a été consacré principalement à la compréhension des mécanismes responsables des dissipations d'énergie dans les matériaux piézo-électriques de zircono titanate de plomb -PZT. Les compositions élaborées sont des zircono titanate de plomb dans la zone morphotropique et répondant à une formulation chimique de type : Pb (Zr1-x Tix)O3 et présentant un rapport Zr/Ti de 0.54/0.46, non dopées (PZT 54/46), dopées au potassium à 0.5% atomique respectivement (PKZT 0.5/24/46 et PKZT 1/54/46), et dopées au niobium à 1%atomique respectivement (PNZT 1/54/46 et PNZT 2/54/46). L'utilisation de la spectrométrie mécanique comme technique principale d'investigation nous a permis la mise en évidence de deux pics de transition de phase P1 et P2, et de deux autres pics de pertes mécaniques R1 et R2; Le pic P1 correspond à la transition de Curie entre la phase para électrique et la phase ferroélectrique quadratique. Le pic P2 représente les pertes associées à la transmission morphotropique entre les phases ferroélectriques quadratique et rhomboédrique. Le pic R2 est contrôlé par un mécanisme de relaxation dû à des interactions simples formant des dipôles élastiques/diélectriques anisotropes entre les lacunes d'oxygène et les lacunes cationiques. Le pic R1 est la superposition de deux pics : L'un est lié au mouvement visqueux des parois de domaines ferroélectriques et à l'évolution de la structure des domaines ferroélectriques, causé par la nucléation de nouveaux domaines, Et l'autre est contrôlé par l'interaction des parois de domaines avec un nuage de défauts ponctuel environnant, et à l'opposition de ces derniers (lacunes cationiques et/ou au complexes de défauts) au mouvement des parois des domaines ferroélectriques.The aim of the present study is the comprehension of the mechanisms controlling the dissipation phenomena in piezoelectric ceramics of lead zirconate titanate-PZT-. We have prepared several piezoelectric ceramics Pb (Zr1-x Tix)O3 close to the morphotropic phase boundary with Zr/Ti ratio of 0.54/0.46, undoped PZT (PZT 54/46), potassium doped PZT at 0.5 %atomic et 1%atomic respectively (PKZT 0.5/54/46 and PKZT 1/54/46), and niobium doped PZT at 1%atomic et 2%atomic respectively (PNZT 1/54/46 et PNZT 2/54/46). By mechanical spectrometry we have observed two phase transition peaks : P1 et P2, and two other mechanical losses peaks : R1 et R2. P1 peaks is the Curie transition peak between tetragonal ferroelectric phase and paraelectric phase. P2 peak is the morphotropic transition between rhombohedral and tetragonal ferroelectric phases. R2 peak is a relaxation controlled mechanism peak due to the formation of dipoles from the interaction between oxygen vacancies and the cationic vacancies and/or dopant ions. R1 peak is the superposition of two peaks : the first is related to the viscous motion of domain walls and the evolution of the ferroelectric domain structure, caused by the nucleation of new domains, the second is controlled by the interaction of domain walls with an neighbouring point defects cloud (rather cationic vacancies), which oppose to the domain walls movement.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

PES-Kaolin Mixed Matrix Membranes for Arsenic Removal from Water

The aim of this work was the fabrication and the characterization of mixed matrix membranes (MMMs) for arsenic (As) removal from water. Membrane separation was combined with an adsorption process by incorporating the kaolin (KT2) Algerian natural clay in polymeric membranes. The effects of casting solution composition was explored using different amounts of polyethersufone (PES) as a polymer, polyvinyl-pyrrolidone (PVP K17) and polyethylene glycol (PEG 200) as pore former agents, N-methyl pyrrolidone (NMP) as a solvent, and kaolin. Membranes were prepared by coupling Non-solvent Induced Phase Separation and Vapour Induced Phase Separation (NIPS and VIPS, respectively). The influence of the exposure time to controlled humid air and temperature was also investigated. The MMMs obtained were characterized in terms of morphology, pore size, porosity, thickness, contact angle and pure water permeability. Adsorption membrane-based tests were carried out in order to assess the applicability of the membranes produced for As removal from contaminated water. Among the investigated kaolin concentrations (ranging from 0 wt % to 5 wt %), a content of 1.25 wt % led to the MMM with the most promising performance

Molecular characterization of canine parvovirus-2 variants circulating in Tunisia

International audienceCanine parvovirus type 2 (CPV2) emerged in 1978 as a highly contagious and very serious disease in dogs. The characterization of CPV2 antigenic types is exclusively based on the identification of the amino acid residue at position 426 of the capsid protein VP2. Currently, three antigenic types CPV-2a (asparagine N-426), CPV-2b (aspartic acid D-426) and CPV-2c (glutamic acid E-426) are circulating worldwide. In Tunisia, despite the fact that many clinical and few serological investigations clearly indicate that CPV is widespread and of major concerns in the local dog population, no molecular and antigenic type characterization of circulating variants has been carried out. This investigation showed that most of clinically presumed CPV infections were confirmed by classical or real-time PCR. When no real-time PCR facilities were affordable, classical PCR as reported here in association with restriction fragment length polymorphism (RFLP) with MboI and MboII can be very useful for screening and diagnosing CPV infections. A total of 50 variants were characterized by sequencing and an almost even representation of the different antigenic types, including CPV-2c and slightly more type 2b, were evidenced. Characterization of the Tunisian variants by MGB probe assays as reported was inefficient for most of CPV-2a variants because of their typical nucleotide mutation C-1269. Phylogenetic analysis showed that the Tunisian variants underwent evolution for a relatively long period of time inside the country. The analysis also showed some crossings of the different antigenic types, leaving both genotypic and phenotypic characteristic mutations

A microconductometric ethanol sensor prepared through encapsulation of alcohol dehydrogenase in chitosan: application to the determination of alcoholic content in headspace above beverages

International audienceA conductometric transducer is proposed for the first time for the detection of ethanol vapor. This ethanol microsensor is prepared by encapsulation of alcohol dehydrogenase (ADH) in chitosan. Interdigitated electrodes fabricated by silicon technology were used. The electrodeposition of chitosan allows the addressing of the chitosan film on the microconductometric devices and to encapsulate ADH and nicotinamide adenine dinucleotide (NAD?), which was monitored by FTIR. The analytical performance of the ethanol microsensor was determined in gaseous methanol, ethanol, and acetone samples, collected from the headspace above aqueous solutions of known concentration. The response time (tRec) of the sensor varies from 7 to 21 s from lower concentrations to higher concentrations. The detection limit is 0.12v/v % in the gas phase, correspondingto 0.22 M in the liquid phase. The relative standard deviation for the same sensor is from 12% for lower concentrations to 2% for higher concentrations. The ethanol sensor presents 2.6 times lower sensitivity for methanol and 28.3 times lower sensitivity for acetone. A detection of ethanol in the headspace of a red wine sample lead to an alcohol content in good agreement with the value given by the producer