Fabrication, microstructure, and properties of fired clay bricks using construction and demolition waste sludge as the main additive

Green routes to prepare or manufacture sustainable building materials have been attracting much attention over the years targeting sustainability issues. In this investigation, for the first time, sludge from the inert mineral part of the construction and demolition waste (RA-S) is used as a primary raw material in the fabrication of fired bricks for building purposes. Fired bricks fabricated with different dosages of RA-S and earth material (i.e., 0%, 30%, 50%, 70%, and 100% by weight) were prepared and evaluated in terms of their physical-chemical properties. The RA-S was characterized, and the results showed that it could be classified as a clayey material and richly graded silty sand according to the French Standards. XRD analysis revealed that the addition of the RA sludge into raw earth material provoked changes slightly in the fired bricks. The compressive strength (CS) results indicated that the CS of the fired bricks increased with the addition of the RA-S from 30% to 70%. The highest CS was attained at the firing temperature of 800 °C. The density of the fired brick slightly reduced with the RA-S addition. The thermal conductivity results suggest that RA-S has better insulation properties compared to earth material. The RA-S sludge can be used in combination with earth material to fabricate fired bricks, which can meet the requirements of many Standards all over the World. In the light of these results, it is possible to say that the RA-S generated from recycling inert mineral part of construction and demolition waste plant is an excellent raw material to prepare efficient fired bricks that can be successfully employed in the real construction sector. Also, the highlighted results suggest that brickwork factories have the opportunity to improve production quality while significantly reducing manufacturing time, energy consumption, resource depletion, and environmental impact.The authors are also grateful to the Council for the Development of Higher Education at Graduate Level, Brazil (CAPES) for the postdoctoral scholarship granted through the National Postdoctoral Program (PNPD). The authors also thank Mr. Ferro, president of Esterel Terassement, for financial support and for providing the RA-S samples. Dr. Simoes dos Reis gives a special thanks to the cooperation opportunity between UFRGS and IFSTTAR through his Post-doctoral studies provided by PNPD. E.C. Lima thanks to Foundation for Research Support of the State of Rio Grande do Sul (FAPERGS), and National Council for Scientific and Technological Development (CNPq, Brazil) for financial support and sponsorship.Peer ReviewedPostprint (author's final draft

Ecological conditions determine extinction risk in co-evolving bacteria-phage populations.

BACKGROUND: Antagonistic coevolution between bacteria and their viral parasites, phage, drives continual evolution of resistance and infectivity traits through recurrent cycles of adaptation and counter-adaptation. Both partners are vulnerable to extinction through failure of adaptation. Environmental conditions may impose unequal abiotic selection pressures on each partner, destabilising the coevolutionary relationship and increasing the extinction risk of one partner. In this study we explore how the degree of population mixing and resource supply affect coevolution-induced extinction risk by coevolving replicate populations of Pseudomonas fluorescens SBW25 with its associated lytic phage SBW25Ф2 under four treatment regimens incorporating low and high resource availability with mixed or static growth conditions. RESULTS: We observed an increased risk of phage extinction under population mixing, and in low resource conditions. High levels of evolved bacterial resistance promoted phage extinction at low resources under both mixed and static conditions, whereas phage populations could survive when phage susceptible bacterial genotypes rose to high frequency. CONCLUSIONS: These findings demonstrate that phage extinction risk is influenced by multiple abiotic conditions, which together act to destabilise the bacteria-phage coevolutionary relationship. The risk of coevolution-induced extinction is therefore dependent on the ecological context

Marina Mayoral, La poesía de Rosalía de Castro

Poullain G. Marina Mayoral, La poesía de Rosalía de Castro. In: Bulletin Hispanique, tome 78, n°1-2, 1976. pp. 148-153

Determination of the thermophysical properties of evolutive porous media: application to Civil Engineering materials

The purpose of this paper is to describe the development and the use of two measurement techniques especially adapted to the rapid determination of the thermophysical properties of evolutive porous media. The first technique exploits the method of the “heated and non-heated wires” and is validated on wet clay by comparison with previous works [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004)]. It is then used to quantify the evolution of both thermal conductivity and volumetric heat capacity of hardening cement pastes maintained at 294 ± 1 K. The second technique is based on the classical method of the “heating film” and a data treatment using forward calculation. This technique is first used to measure the properties of well-known materials (hardened mortars, wet sand [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004); Delacre, Ph.D. thesis, University of Artois, 2000] and glass [Bastian, Rev. Phys. Appl. 22, 431 (1987)] and then applied to media whose properties evolve both over time and through space (drying sand)

Influence of the secondary phases and post-annealing on the transport current density of sinter-forged (Bi, Pb)-2223 ceramics

Transport critical current measurements were performed at 77 K on bulk silver-less (Bi, Pb)2Sr2Ca2Cu3O10+x ceramics textured by slow sinter-forging process. The influences of the 85 K superconductive 2212 phase and non-superconductive secondary phases (SrxCa1−x)2PbO4, (Sr,Ca)14Cu24Oy and (SrxCa1−x)2CuO3, are discussed in terms of their amounts, their grain sizes and shapes and their distribution among the 2223 matrix. The importance of the temperature profile and the atmosphere the annealing that follows the sinter-forging process is clearly demonstrated

EBIC and conductance measurements in poly- and bicrystalline silicon

Grain boundaries cut from polycrystalline solar cells were investigated by E.B.I.C. mode. Only the exact mirror twin Σ3 shows no electrical activity. In order to explain the two types of behaviour of the twin Σ9, the segregation of impurities must be taken into account. The other boundary planes analyzed are either symmetric with a deviation from the exact coincidence (Σ3, 5) or asymmetric (Σ3, 9, 25, 27). The conductance of several bicrystals (Σ9, 13, 25, 27) was measured on as-grown bicrystals and after annealing.L'analyse de la recombinaison des porteurs minoritaires par E.B.I.C. sur des cellules solaires en silicium polycristallin montre que seule la macle miroir Σ3 de plan {111}, sans déviation à la coincidence exacte et sans décoration, ne montre aucune activité électrique. L'influence de la ségrégation est prise en considération pour expliquer les différents comportements de la macle miroir Σ9 de plan {221} . Deux joints présentant des écarts à la coincidence sont faiblement actif (Σ3) ou fortement actif (Σ5). Des mesures de conductance sont réalisées sur des bicristaux (Σ9, 13, 25, 27), à l'état brut de tirage et après différents traitements thermiques

Eddy currents A misleading contribution when measuring magnetoelectric voltage coefficients of thin film devices

International audienceTb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) magnetoelectric (ME) thin films were deposited on Pt/TiO2/SiO2/Si substrate. The ME voltage coefficient αH ME was determined at room temperature using a lock-in amplifier and by applying to the sample an alternating magnetic field of a few mT. Surprisingly, very similar responses were obtained from a simple commercial capacitor set in series with a small loop of wire. This allowed us first to accurately model and reproduce the frequency response of the ferroelectric PZT layer alone. We also observed that, at low frequency, the voltage across the ferroelectric capacitor and the current in the circuit did not decrease significantly when diminishing then removing, the area of the conductive loop. One major conclusion is that eddy currents in the lead wires, rather than the classical electromotive force across conductive loops, contribute significantly to the total voltage response, at least for thin film ME devices. A model taking into account eddy currents was then developed for the extraction of the true αH ME. A large αH ME of 4.6V/cm.Oe was thus obtained for the Terfenol-D/Pt/PZT thin film device, without DC magnetic field. © 2015 AIP Publishing LLC